Dr Matt Parker is Senior Lecturer in Neuroscience. He was educated (BSc, MSc, PhD) at the University of Southampton. Following post doctoral fellowships at the Royal Veterinary College and Queen Mary University of London, he worked as Lecturer in Cell Biology and Developmental Genetics at Queen Mary University of London and Nanchang Medical School (China). He then worked at the University of Portsmouth 2015-2022, where he established the Brain and Behaviour Lab and the Portsmouth zebrafish facility. He left Portsmouth in 2022 to join the School of Biosciences at Surrey as a Senior Lecturer in Neuroscience. His research focusses on how our personalities impact upon how we respond to stress. His group approaches this problem by employing basic and translational neuroscience and psychopharmacology, and applies it in both clinical and pre-clinical settings. Since working at Queen Mary, he helped to establish zebrafish as a model organism in behavioural neuroscience, developed a number of now widely used behavioural protocols in this species, and inspired the development of commercially available automated behavioural tracking devices. His group currently is generously supported by funding from BBSRC, NC3Rs, 3Z Pharmaceutical, Dstl, and the ALS association (with University of Sheffield and University of Exeter).
As well as his academic work, Dr Parker sits of external panels and committees, including the BBSRC panel of experts (committee A), the NC3Rs Skills and Knowledge Transfer Partnership panel, and the European Commission (Horizon Europe (HORIZON) - Evaluation). He previously sat as a member of the UK Home Office Animals in Science Committee (2013-2016).
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My group’s research aims to understand the underlying biology of neuropsychiatric, neurodevelopmental and neurodegenerative disorders. Our approach is theoretically guided by the principles of precision medicine, i.e., that understanding the biology of these disorders, and in particular, their transdiagnostic features, will help develop individualised treatments for patients. Our approaches broadly span behavioural and affective neuroscience, experimental psychopharmacology, and molecular genetics, and we receive funding broadly from UKRI, charities and industry. We use zebrafish as a model system.
Indicators of esteem
BBSRC Panel A - Member of Panel of Experts (2022 - present)
NC3Rs Member of 'Skills and Knowledge Transfer Grants' Panel (2022-present)
National Science Center (NCN; Poland) Member of NZ7 panel (Diagnostic Tools, Therapies and Public Health) (2022-present)
Associate Editor for the Journal of Veterinary Behavior
National Science Center (NCN; Poland) Member of OPUS Life Sciences LS7 Panel (Diagnostic tools, therapies and public health) 2023-present
My group’s research aims to understand the underlying biology of neuropsychiatric, neurodevelopmental and neurodegenerative disorders. Our approach is theoretically guided by the principles of precision medicine, i.e., that understanding the biology of these disorders, and in particular, their transdiagnostic features, will help develop individualised treatments for patients. Our approaches broadly span behavioural and affective neuroscience, experimental psychopharmacology, and molecular genetics, and we receive funding broadly from UKRI, charities and industry. We use zebrafish as a model system.
Indicators of esteem
BBSRC Panel A - Member of Panel of Experts (2022 - present)
NC3Rs Member of 'Skills and Knowledge Transfer Grants' Panel (2022-present)
National Science Center (NCN; Poland) Member of NZ7 panel (Diagnostic Tools, Therapies and Public Health) (2022-present)
Associate Editor for the Journal of Veterinary Behavior
National Science Center (NCN; Poland) Member of OPUS Life Sciences LS7 Panel (Diagnostic tools, therapies and public health) 2023-present
Postgraduate research supervision
Courtney Hillman (2022-2025) Understanding and predicting the interactions of narcotic and pharmaceutical mixtures using the zebrafish model
Pooja Ram (2023-2027) Nanoplastics in the food chain: from food, to cells, to function
Austin Cooper (2023-2027) The use of zebrafish as a model for longitudinal objective assessment of endogenous circadian rhythms
Module convener - Fundamentals of Sports Psychology BMS2064
I teach Cardiac Physiology on BMS1032 (Introduction to Principles of Physiology and Practical Skills)
Sveinsdóttir, H.S., Christensen, C., Þorsteinsson, H., Lavalou, P., Parker, M.O., Shkumatava, A., Norton, W.H.J., Andriambeloson, E., Wagner, S. & Karlsson, K.Æ. (2022). Novel non-stimulants rescue hyperactive phenotype in an adgrl3.1 mutant zebrafish model of ADHD. Neuropsychopharmacology. (Available online).
Ismail, V., Zachariassen, L., Godwin, A., Ellard, S., Stals, K.L., Brown, K.T., Foulds, N., Wheway, G., Parker, M.O., Sahakian, M, Lyngby, S.M., Pedersen, M.G., Desir, J., Bayat, A., Musgaard, M., Guille, M., Kristensen, A.S., Barelle, D. (2022). Identification and functional evaluation of GRIA1 missense and truncation variants in individuals with intellectual disability: An emerging neurodevelopmental syndrome. American Journal of Human Genetics. (Available online).
Lewis, K., Proops, L., Parker, M.O., McBride, S.D. (2022). Risk factors for stereotypic behaviour in captive ungulates. Proceedings of the Royal Society B: Biological Sciences. (Available online).
Clay, J.M., Parker, M.O. (2020). Alcohol use and misuse during the COVID-19 pandemic: a potential public health crisis? The Lancet Public Health, e259.
The acquisition of executive skills such as working memory, decision-making and adaptive responding occur at different stages of central nervous system development. Zebrafish (Danio rerio) are increasingly used in behavioural neuroscience for complex behavioural tasks, and there is a critical need to understand the ontogeny of their executive functions. Zebrafish across developmental stages (4, 7, 14, 30 and 90 days post fertilisation (dpf)), were assessed to track development of working memory (WM) and behavioural flexibility (BF) using the free movement pattern Y-maze (FMP Y-maze). Several differences in both WM and BF were identified during the transition from yolk-dependent to independent feeding. Specifically, WM is evident in all age groups, even from 4 dpf. However, BF is not developed until larvae start free feeding, and show significant improvement thereafter, with young adults (90 dpf) demonstrating the most well-defined BF. We demonstrate, for the first time, objective WM processes in 4 dpf zebrafish larvae. This suggests that those wishing to study WM in zebrafish may be able to do so from 4 dpf, thus drastically increasing throughput. In addition, we show that zebrafish follow distinct stages of cognitive development and age-related changes during the early developmental period. Finally, our findings indicate distinct WM and BF mechanisms, which may be useful to study for translational purposes. •Zebrafish show evidence of working memory from 4 days post fertilisation.•Zebrafish larvae develop behavioural flexibility at 7 days post fertilisation.•Zebrafish larvae as young as 4 days post fertilisation could be used for high throughput analyses of cognitive development.
This large, international dataset contains survey responses from N = 12,570 students from 100 universities in 35 countries, collected in 21 languages. We measured anxieties (statistics, mathematics, test, trait, social interaction, performance, creativity, intolerance of uncertainty, and fear of negative evaluation), self-efficacy, persistence, and the cognitive reflection test, and collected demographics, previous mathematics grades, self-reported and official statistics grades, and statistics module details. Data reuse potential is broad, including testing links between anxieties and statistics/mathematics education factors, and examining instruments' psychometric properties across different languages and contexts. Data and metadata are stored on the Open Science Framework website [https://osf.io/mhg94/?view_only=9d70d0facfeb476987f32d4ab156ecdc].
With lifespans rapidly increasing worldwide there has been a marked increase in age-related diseases—particularly those affecting cognition—that place a major socioeconomic burden on society. Despite this, much of what occurs during the aging process at a molecular level is poorly understood, facilitating the need for a greater understanding of the processes involved. In recent years, zebrafish have proved a useful model for the identification of genetic and cellular mechanisms affecting a variety of disease processes. Here we review the potential of zebrafish as a model for the study of cognitive ageing.
The use of multiple species to model complex human psychiatric disorders, such as ADHD, can give important insights into conserved evolutionary patterns underlying multidomain behaviors (e.g., locomotion, attention, and impulsivity). Here we discuss the advantages and challenges in modelling ADHD-like phenotypes in zebrafish (Danio rerio), a vertebrate species that has been widely used in neuroscience and behavior research. Moreover, multiple behavioral tasks can be used to model the core symptoms of ADHD and its comorbidities. We present a critical review of current ADHD studies in zebrafish, and how this species might be used to accelerate the discovery of new drug treatments for this disorder.
Obsessive compulsive disorder (OCD) is a pervasive, debilitating neuropsychiatric disorder. Despite over half a century of effort, OCD has remained remarkably resistant to treatment, partly owing to a lack of understanding of the underlying biology. Recently, there has been a growing consensus that in order to understand the basis of neuropsychiatric disorders such as OCD, we should focus on transdiagnostic, observable, measurable behavioral or neural elements, endophenotypes. Zebrafish have the well-characterized neural development and available cutting-edge genetic tools that make them the ideal species for studying psychiatric disorders. In addition, a number of endophenotypes linked to OCD have been observed, and can be objectively measured, in zebrafish. In this chapter, some key behavioral tests of relevance to OCD will be outlined. If the neural substrates underlying these behaviors are elucidated, this may represent significant progress in understanding the biological underpinnings of OCD. This will ultimately lead to increased specificity for drug discovery, as well as providing targets for personalized treatments for one of the most common neuropsychiatric disorders.
Externalizing disorders (ED) are a cause of concern for public health, and their high heritability makes genetic risk factors a priority for research. Adhesion G-Protein-Coupled Receptor L3 (ADGRL3) is strongly linked to several EDs, and loss-of-function models have shown the impacts of this gene on several core ED-related behaviors. For example, adgrl3.1 −/− zebrafish show high levels of hyperactivity. However, our understanding of the mechanisms by which this gene influences behavior is incomplete. Here we characterized, for the first time, externalizing behavioral phenotypes of adgrl3.1 −/− zebrafish and found them to be highly impulsive, show risk-taking in a novel environment, have attentional deficits, and show high levels of hyperactivity. All of these phenotypes were rescued by atomoxetine, demonstrating noradrenergic mediation of the externalizing effects of adgrl3.1 . Transcriptomic analyses of the brains of adgrl3.1 −/− vs. wild-type fish revealed several differentially expressed genes and enriched gene clusters that were independent of noradrenergic manipulation. This suggests new putative functional pathways underlying ED-related behaviors, and potential targets for the treatment of ED.
Salient landmarks enhance route learning. We hypothesised that semantically salient nostalgic landmarks would improve route learning compared to non-nostalgic landmarks. In two experiments, participants learned a route through a computer-generated maze using directional arrows and wall-mounted pictures. On the test trial, the arrows were removed, and participants completed the maze using only the pictures. In the nostalgia condition, pictures were of popular music artists and TV characters from 5 to 10 years ago. In the control condition, they were recent pictures of these same artists and characters. In Experiment 1, in the test trial, participants in the nostalgia condition completed the maze faster than controls. Experiment 2 conceptually replicated these findings and extended them by exploring boundary conditions. Participants had to learn two mazes sequentially. In Maze 1, we placed nostalgic/control landmarks only at non-decision points (whereas we placed them at decision points in Experiment 1). In Maze 2, we placed nostalgic/control landmarks at decision points during acquisition but removed them in the test trial (whereas they were present in the test trial in Experiment 1). In both mazes, participants in the nostalgia (compared to control) condition completed the test trial faster.
Social isolation has detrimental health effects, but the underlying mechanisms are unclear. Here, we investigated the impact of 2 weeks of isolation on behavior and gene expression in the central nervous system at different life stages of zebrafish. Results showed that socially deprived young adult zebrafish experienced increased anxiety, accompanied by changes in gene expression. Most gene expression patterns returned to normal within 24 hours of reintroduction to a social environment, except angptl4, which was upregulated after reintroduction, suggesting an adaptive mechanism. Similarly, aging zebrafish displayed heightened anxiety and increased central nervous system expression of angptl4 during isolation, but effects were reversed upon reintroduction to a social group. The findings imply that angptl4 plays a homeostatic role in response to social isolation, which varies across the lifespan. The study emphasizes the importance of social interactions for psychological well-being and highlights the negative consequences of isolation, especially in older individuals. Further research may unravel how social isolation affects angptl4 expression and its developmental and aging effects.
Stress, trait impulsivity, and emotional dysregulation are independent predictors of alcohol use and misuse, but little is known about the potential mechanisms that link these risk factors together. To address this issue, we carried out an exploratory cross-sectional study, on UK-based participants. Our preregistered, hypothesised theoretical framework was that emotional dysregulation mediates the association between cumulative lifetime stressor exposure and lifetime alcohol use. We also hypothesised that heightened impulsivity would strengthen these relations. As hypothesised, emotional dysregulation fully mediated the relation between cumulative lifetime stressor exposure and lifetime alcohol use. Several facets of impulsivity moderated these associations. For example, as levels of negative urgency increased, the associations between cumulative lifetime stressor exposure and emotional dysregulation, emotional dysregulation and lifetime alcohol use, and lifetime stress exposure and lifetime alcohol use, via emotional dysregulation, strengthened. These preliminary findings propose a theoretically framed model which integrates several prominent risk-factors for alcohol misuse, extending prior research and generating interesting and novel lines of enquiry for longitudinal and cross-cultural analyses. The findings also highlight the potential clinical utility of screening for lifetime stress exposure while tailoring personalised treatment interventions.
Global dispersal and increasing frequency of the SARS-CoV-2 spike protein variant D614G are suggestive of a selective advantage but may also be due to a random founder effect. We investigate the hypothesis for positive selection of spike D614G in the United Kingdom using more than 25,000 whole genome SARS-CoV-2 sequences. Despite the availability of a large dataset, well represented by both spike 614 variants, not all approaches showed a conclusive signal of positive selection. Population genetic analysis indicates that 614G increases in frequency relative to 614D in a manner consistent with a selective advantage. We do not find any indication that patients infected with the spike 614G variant have higher COVID-19 mortality or clinical severity, but 614G is associated with higher viral load and younger age of patients. Significant differences in growth and size of 614G phylogenetic clusters indicate a need for continued study of this variant.
Externalising disorders (ED) are a cause of concern for public health, and their high heritability make genetic risk factors a priority for research. Adhesion G Protein-Coupled Receptor L3 (ADGRL3) is strongly linked to several EDs, and loss-of-function models have shown impacts of this gene on several core ED-related behaviors. For example, adgrl3.1-/- zebrafish show high levels of hyperactivity. However, our understanding of the mechanisms by which this gene influences behavior is incomplete. Here we characterized, for the first time, externalizing behavioral phenotypes of adgrl3.1-/- zebrafish and found them to be highly impulsive, show boldness in a novel environment, have attentional deficits, and show high levels of hyperactivity. All of these phenotypes were rescued by atomoxetine, demonstrating noradrenergic mediation of the externalizing effects of adgrl3.1. Transcriptomic analyses of the brains of adgrl3.1-/- vs wild type fish revealed several differentially expressed genes and enriched gene clusters that were independent of noradrenergic manipulation. This suggests new putative functional pathways underlying ED-related behaviors, and potential targets for the treatment of ED. Competing Interest Statement The authors have declared no competing interest.
Background Exposure to stress and trait impulsivity are independent predictors of relapse in recovering alcoholics, but potential mechanisms that link these two risk-factors in terms of their putative additive or interactive contributions to relapse are not known. The aim of this study was to use a model of stress-induced relapse to test the hypothesis that acute psychosocial stress increases craving for alcohol in social drinkers. We also tested the hypothesis that change in craving could be explained by variability in impulsivity and risk-taking. Methods Participants completed questionnaires to assess drinking behaviour (Alcohol Dependence Questionnaire [ADQ]; and an Alcohol Use Disorders Identification Test [AUDIT]), craving (Desires for Alcohol Questionnaire [DAQ] and impulsivity (Barrett Impulsiveness Scale [BIS]). Participants also completed two computer tasks to assess risk-taking and impulsivity, the Balloon Analogue Risk Test (BART) and a continuous performance task (CPT). Participants then underwent the Trier Social Stress Test (TSST), and completed a final DAQ to assess post-stress craving. Results Participants showed an increase in craving following exposure to the TSST. In addition, risk-taking was positively correlated with change in craving. Conclusions Our data suggests that acute psychosocial stress increases subjective craving in social drinkers, but that the effects may be trait-dependent, with stress-induced increases in craving correlated with risk-taking.
Rationale: Hazardous drinking presents a global health risk and if chronic, can escalate into an alcohol use disorder. The causal mechanisms for the transition from controlled alcohol use to uncontrolled misuse and dependence are complex, and it is not presently possible to accurately predict those most at-risk of misusing alcohol, or of developing AUD. Objectives: We investigated the feasibility of using ecological momentary assessments, specifically related to daily stress and alcohol use, to study risk factors for hazardous drinking. We tested the hypothesis that in a sample of healthy drinkers, risk-taking would modulate the impact of daily self-reported stress on alcohol use. Methods: We characterised impulsivity/risk-taking in 23 participants (12 female; mean age = 24.59 [SD = 5.34]) using a battery of questionnaires and computer tasks. We then collected daily behavioural and physiological data related to self-reported stress levels and blood alcohol concentration consumption for 30 days. Results: Attrition and missing data rates were low, with an overall response rate of 92.6% We found support for our hypothesis, with higher risk-taking and impulsive participants drinking more following daily stressors. However, the picture was not clear, with participants drinking greater volumes of alcohol at weekends, and the interactions of stress x personality trait often differing on weekdays. Conclusions: This feasibility study demonstrated the potential for was the first to demonstrate that using ecological momentary assessments, such as, digital biomarkers to assess risk factors for alcohol misuse is a viable option for investigating the effects of neurocognitive endophenotypes and stress on alcohol misuse on a longitudinal basis.
Abstract Simple mazes have provided numerous tasks for assessing working memory. The discrete nature of choices in the T-maze has provided a robust protocol with sensitivity to cognitive deficits, whilst the continuous Y-maze reduces manual handling and pre-trial training. We have combined these attributes to develop a new behavioural task for assessing working memory, the Free-movement pattern (FMP) Y-maze. Using sequentially recorded left and right turns we demonstrate that zebrafish and mice use a single dominant strategy predominantly consisting of alternations between left and right choices trial-to-trial. We further tested this protocol with Drosophila and discovered an alternative invertebrate search strategy. Finally, a virtual human FMP Y-maze confirmed a common strategy among all tested vertebrate species, validating the translational power of the task for human research. The FMP Y-maze combines robust investigation of working memory and high translational power, generating a simple task with far-reaching impact.
A high level of anxiety is a characteristic symptom across the anxiety spectrum disorders and several other affective disorders, and is often detected early in a child's development. Zebrafish are widely used in translational studies for drug discovery in anxiety research, where the species naturalistic diving response to a new environment is a reliable and validated marker for anxiety-like behavior. Here, we present for the first time a method for examining diving behavior in zebrafish larvae to assess anxiety-like behaviors at early-stages (7 days-post-fertilization). Anxiogenic (caffeine 100 mg/L) and anxiolytic (diazepam 5 mg/L) drugs were used to pharmacologically validate the protocol. Larvae were pretreated in drug (or fresh water) for 30-min, then transferred to cuvettes containing fresh water and habituated for a further 30-min. Larval diving response (LDR) was then recorded using an automated system (Zantiks) for 30-min. As with adult fish, diazepam was anxiolytic, significantly reducing the time spent in bottom of the novel environment, and increasing the time spent in the top. Meanwhile, caffeine induced anxiogenic-like effects by increasing the time spent in the bottom zone of the environment. This new automated and high-throughput screening tool has the potential use for screening of anxiogenic and anxiolytic compounds, and for studies aiming to understand the mechanisms underlying affective disorders. Competing Interest Statement The authors have declared no competing interest.
Abstract Healthy aging is associated with a decline in memory and executive function, which have both been linked with aberrant dopaminergic signalling. We examined the relationship between cognitive performance and dopamine function of young and aging zebrafish (Danio rerio). We revealed age-related decreases in working memory and cognitive flexibility in the Free-Movement Pattern (FMP) Y-maze. An increase in drd5 gene expression in aging adults coincided with a decrease in cognitive performance. Treatment with a D1/D5 receptor agonist (SKF-38393, 35 μM) 30 minutes prior to behavioural assessment resulted in improved working memory in aging zebrafish, but no effect in younger adults. However, an ‘overdosing’ effect caused by agonist treatment resulted in downregulation of dat expression in 6-month old, treated zebrafish. The translational relevance of these findings was tested in humans by analysing exploratory behaviour in young-adult, 18-35-year olds, and aged adults, 70+ year olds, in a virtual FMP Y-maze. Our findings revealed similar age-related decline in working memory. Thus, strongly supporting zebrafish as a translational model of aging and cognitive decline. Competing Interest Statement The authors have declared no competing interest. Footnotes * The measurements for the Y maze were incorrect in a previous version
To facilitate smoking genetics research we determined whether a screen of mutagenized zebrafish for nicotine preference could predict loci affecting smoking behaviour. From 30 screened F3 sibling groups, where each was derived from an individual ethyl-nitrosurea mutagenized F0 fish, two showed increased or decreased nicotine preference. Out of 25 inactivating mutations carried by the F3 fish, one in the slit3 gene segregated with increased nicotine preference in heterozygous individuals. Focussed SNP analysis of the human SLIT3 locus in cohorts from UK (n=863) and Finland (n=1715) identified two variants associated with cigarette consumption and likelihood of cessation. Characterisation of slit3 mutant larvae and adult fish revealed decreased sensitivity to the dopaminergic and serotonergic antagonist amisulpride, known to affect startle reflex that is correlated with addiction in humans, and increased htr1aa mRNA expression in mutant larvae. No effect on neuronal pathfinding was detected. These findings reveal a role for SLIT3 in development of pathways affecting responses to nicotine in zebrafish and smoking in humans.
Rationale Chronic alcohol misuse can escalate into alcohol use disorder (AUD). The causal mechanisms through which recreational social drinking develops into compulsive uncontrolled alcohol misuse are multifaceted. For example, stress is an important risk factor that influences alcohol craving in both healthy and addicted individuals. In addition, those that are high in impulsivity/risk taking drink more and are at greater risk of developing addiction. At present, however, it is not possible accurately to predict those at risk of escalation in alcohol use, or of developing AUD. Objectives The aim of this study was to investigate how underlying physiological and personality traits affect stress-induced craving for, and consumption of, alcohol, in a sample of healthy social drinkers. The primary hypothesis was that impulsivity/risk-taking would modulate stress-induced alcohol craving and consumption. Methods Thirty-nine participants (22 male and 17 female; mean age = 23.92 years [SD = 4.90]) were randomly allocated to “stress” and “no-stress” groups; in the stress group participants took part in the Trier Social Stress Test (TSST). Participants completed several questionnaires and computer tasks in order to assess prior alcohol use, impulsivity/risk-taking, stress-reactivity, craving and physiological biomarkers of stress. Finally, participants completed a voluntary drinking task, in which increasing numbers of presses on a computer keyboard were reinforced with 5ml shots of 37% ABV vodka (plus mixer). Results Participants exposed to the TSST showed an increase in craving following the stressor. Several factors predicted voluntary drinking, including risky decision making, slow HR recovery from stress, poor vagal tone during recovery from stress and greater stress reactivity. Surprisingly, we found no correlation between craving and consumption. Conclusions Our data suggest that variation in physiological stress parameters and poor decision-making abilities increase risk of stress-induced alcohol consumption. This may provide a useful translational framework through which we can further study early predictive markers for the shift between controlled recreational drinking to uncontrolled alcohol misuse, including AUD.
Early-life adversity impacts on anxiety-related behaviors in adulthood. The effects of such adversity not only affect the animal itself, but can be passed on transgenerationally. Pervasive effects of experimentally-induced early-life stress (ELS) have been documented in adult zebrafish but it is not clear if this can be passed on via the germline. Here, we investigated the effects of ELS across three generations, by analyzing the responses of adult animals exposed to ELS in two different anxiety-related tasks, as well as in social behavior, memory, and cognition. Animals exposed to ELS (at 7 days-post-fertilization) showed a marked attenuation of specific anxiety-related behaviors (F0) as adults, and these alterations were maintained across two subsequent generations (F1 and F2). This suggest zebrafish may be a useful model organism to study the transgenerational effects of ELS, and how this pertains to (for example) neuropsychiatric disorders. In addition, our data may naturally provoke questions regarding consideration of the environment of laboratory-housed zebrafish at early developmental stages. In particular, more work may be necessary to determine how different environmental stressors could affect data variability across laboratories.
Physiological and psychological stress are accompanied by nonverbal behaviour across a wide range of species. The function of this ‘stress behaviour’ is not well understood but is often assumed to be read by others as a cue to stress. Displaying signs of weakness is, however, difficult to understand from an evolutionary perspective and therefore further investigation into why these behaviours exist is needed. Here, we test whether displacement behaviours (i.e., those known to be associated with stress) are reliable indicators of stress in humans. To do this, we presented raters (N = 133) with videos of individuals (N = 31) undergoing a stress-inducting task. Self-directed displacement behaviours and self-reported stress were both associated with stress ratings given by raters. Therefore, such behaviours can provide reliable information to others and can be considered communicative. Individuals producing more nonverbal stress behaviour were rated as more likeable by raters (perhaps presenting as more honest signallers), indicating a benefit and potential adaptive function of displaying stress. Raters also differed in their accuracy in detecting stress from nonverbal cues. Findings suggest that the accuracy with which individuals were able to detect stress was linked to the number of social connections they reported to have. However, this association was non-linear, with individuals who were most and least accurate reporting the least network connections. This could indicate that the ability to read behaviour is associated with an ability to form and maintain social networks.
Adolescents are the next generation of consumers with the potential to raise standards of farm animal welfare—to theirsatisfaction—if their preferences and concerns are translated into accurate market drivers and signals. There are no published data about adolescent views of farm animal welfare to allow meaningful design, implementation, and evaluation of educational strategies to improve consideration of—and behavior toward—farm animals. Knowledge of farm animal welfare, as well as beliefs and attitudes about farm animal welfare and behavioral intention relevant to it were determined in a sample of ukadolescents, using a survey incorporating an extended version of the theory of planned behavior and novel assessment tools. Our results indicate that adolescents have only a limited knowledge of welfare problems for farm animals and welfare-relevant product labels. Intentions to identify welfare standards for the animals from whom their food was derived were weak. Although they cared about farm animal welfare and agreed with fundamental principles—for example, the provision of space and the absence of pain and suffering—like adults they held limited belief in the power and responsibility that they possess through their choices as consumers; responsibility was often shifted to others, such as the government and farmers.
Spatial anxiety (i.e., feelings of apprehension and fear about navigating everyday environments) can adversely impact people's ability to reach desired locations and explore unfamiliar places. Prior research has either assessed spatial anxiety as an individual-difference variable or measured it as an outcome, but there are currently no experimental inductions to investigate its causal effects. To address this lacuna, we developed a novel protocol for inducing spatial anxiety within a virtual environment. Participants first learnt a route using directional arrows. Next, we removed the directional arrows and randomly assigned participants to navigate either the same route (n = 22; control condition) or a variation of this route in which we surreptitiously introduced unfamiliar paths and landmarks (n = 22; spatial-anxiety condition). The manipulation successfully induced transient (i.e., state-level) spatial anxiety and task stress but did not significantly reduce task enjoyment. Our findings lay the foundation for an experimental paradigm that will facilitate future work on the causal effects of spatial anxiety in navigational contexts. The experimental task is freely available via the Open Science Framework (https://osf.io/uq4v7/).
ADHD is a highly prevalent neurodevelopmental disorder. The first-line therapeutic for ADHD, methylphenidate, can cause serious side effects including weight loss, insomnia, and hypertension. Therefore, the development of non-stimulant-based therapeutics has been prioritized. However, many of these also cause other effects, most notably somnolence. Here, we have used a uniquely powerful genetic model and unbiased drug screen to identify novel ADHD non-stimulant therapeutics. We first found that adgrl3.1 null (adgrl3.1 −/−) zebrafish larvae showed a robust hyperactive phenotype. Although the hyperactivity was rescued by three ADHD non-stimulant therapeutics, all interfered significantly with sleep. Second, we used wild-type zebrafish larvae to characterize a simple behavioral phenotype generated by atomoxetine and screened the 1200 compound Prestwick Chemical Library® for a matching behavioral profile resulting in 67 hits. These hits were re-assayed in the adgrl3.1 −/−. Using the previously identified non-stimulants as a positive control, we identified four compounds that matched the effect of atomoxetine: aceclofenac, amlodipine, doxazosin, and moxonidine. We additionally demonstrated cognitive effects of moxonidine in mice using a T-maze spontaneous alternation task. Moxonidine, has high affinity for imidazoline 1 receptors. We, therefore, assayed a pure imidazoline 1 agonist, LNP599, which generated an effect closely matching other non-stimulant ADHD therapeutics suggesting a role for this receptor system in ADHD. In summary, we introduce a genetic model of ADHD in zebrafish and identify five putative therapeutics. The findings offer a novel tool for understanding the neural circuits of ADHD, suggest a novel mechanism for its etiology, and identify novel therapeutics. Neuropsychopharmacology; https://doi.
Numerous neurodegenerative and psychiatric disorders are associated with deficits in executive functions such as working memory and cognitive flexibility. Progress in developing effective treatments for disorders may benefit from targeting these cognitive impairments, the success of which is predicated on the development of animal models with validated behavioural assays. Zebrafish offer a promising model for studying complex brain disorders, but tasks assessing executive function are lacking. The Free-movement pattern (FMP) Y-maze combines aspects of the common Y-maze assay, which exploits the inherent motivation of an organism to explore an unknown environment, with analysis based on a series of sequential two-choice discriminations. We validate the task as a measure of working memory and executive function by comparing task performance parameters in adult zebrafish treated with a range of glutamatergic, cholinergic and dopaminergic drugs known to impairworking memory and cognitive flexibility. We demonstrate the cross-species validity of the task by assessing performance parameters in adapted versions of the task for mice and Drosophila, and finally a virtual version in humans, and identify remarkable commonalities between vertebrate species’ navigation of the maze. Together, our results demonstrate that the FMP Y-maze is a sensitive assay for assessing working memory and cognitive flexibility across species from invertebrates to humans, providing a simple and widely applicable behavioural assay with exceptional translational relevance.
This dataset pertains to: Fontana, B.D., Cleal, M., Parker, M.O. (2019). Female adult zebrafish (Danio rerio) show higher levels of anxiety-like behavior than males, but do not differ in learning and memory capacity. European Journal of Neuroscience.
This dataset pertains to: Fontana, B.D., Cleal, M., Norton, W.H.J., Parker, M.O. (2021). The impact of chronic unpredictable early-life stress (CUELS) on boldness and stress-reactivity: differential effects of stress duration and context of testing. Physiology & Behavior
Environmental enrichment by increasing foraging behaviour and providing food item choice are widely practised and generally accepted as effective methods for reducing stereotypic behaviour in captive animals. In this study, the effectiveness of increasing foraging patch choice and food item choice on reducing motor stereotypy in two captive vicugna were examined For the purposes of the study, first, browse was added to the vicugna's enclosure as an additional forage item and, second, the vicugna's normal feed was divided: half being provided in the indoor quarters and half in the outdoor yard. The results revealed that providing browse as an additional forage item increased the observed stereotypic behaviour, however, dividing the vicugna's feed and therefore increasing forage patch choice, decreased stereotypy. This study was limited because of the small sample size and because the area in which the vicugna were performing stereotypic behaviour was partially visually obscured. However, this study has implications for animal welfare because it highlights the need to evaluate the suitability of foraging enrichment items, and suggests that more research into accommodating the adaptive foraging behaviour of this species in captivity may be necessary.
•Genotype (DRD4) did not have a significant effect on any of the parameters measured.•Spontaneous blink rate but not behavioural initiation rate correlated significantly with levels of impulsivity.•There was no clear association of heart rate variability parameters with either measures of central dopaminergic activity or impulsivity/compulsivity.•Some aspects of the data suggest that the horse may be a useful animal model for assessing the genetic and environmental factors that lead to the physiological and behavioral phenotype of human addiction. Stress and genotype elicit changes in impulse control in a range of species that are attributable to adaptations in both the central and peripheral nervous system. We examined aspects of this mechanism in the horse by assessing the effect of a dopamine receptor genotype (DRD4) and central dopaminergic tone (measured via spontaneous blink rate [SBR] and behavioral initiation rate [BIR]), on measures of impulsivity, compulsivity (3-choice serial reaction time task) and sympathetic/ parasympathetic system balance (heart rate variability [HRV]). Genotype did not have a significant effect on any of the parameters measured. SBR but not BIR correlated significantly with levels of impulsivity. There was no clear association of HRV parameters with either measures of central dopaminergic activity or impulsivity/compulsivity. Overall, some elements of the data suggest that the horse may be a useful animal model for assessing the genetic and environmental factors that lead to the physiological and behavioral phenotype of human addiction, particularly when considering the relationship between central dopaminergic tone and impulsivity.
Regulatory agencies recommend that centrally active drugs are tested for abuse potential before approval. Standard preclinical assessments are conducted in rats or non-human primates (NHPs). This study evaluated the ability of the zebrafish conditioned place preference (CPP) model to predict human abuse outcomes. Twenty-seven compounds from a variety of pharmacological classes were tested in zebrafish CPP, categorized as positive or negative, and analyzed using standard diagnostic tests of binary classification to determine the likelihood that zebrafish correctly predict robust positive signals in human subjective effects studies (+HSE) and/or Drug Enforcement Administration drug scheduling. Results were then compared with those generated for rat self-administration and CPP, as well as NHP self-administration, using this same set of compounds. The findings reveal that zebrafish concordance and sensitivity values were not significantly different from chance for both +HSE and scheduling. Although significant improvements in specificity and negative predictive values were observed for zebrafish relative to +HSE, specificity without sensitivity provides limited predictive value. Moreover, assessments in zebrafish provided no added value for predicting scheduling. By contrast, rat and NHP models generally possessed significantly improved concordance, sensitivity, and positive predictive values for both clinical measures. Although there may be predictive value with compounds from specific pharmacological classes (e.g., -opioid receptor agonists, psychostimulants) for zebrafish CPP, altogether these data highlight that using the current methodology, the zebrafish CPP model does not add value to the preclinical assessment of abuse potential.
Commercially farmed animals are frequently housed in conditions that impose a number of concurrent environmental stressors. For pigs housed indoors, elevated levels of mechanical noise, atmospheric ammonia and low light intensities are commonplace. This experiment examined the effects on growing pigs of chronic exposure to combinations of commercially relevant levels of these potential stressors. Four-week-old hybrid female pigs (n = 224) were housed under experimentally manipulated conditions of nominally either
The effects of common and concurrent environmental stressors on the social behaviour of farm animals are poorly understood. Here, we report the results of a multifactorial experiment designed specifically to examine the individual, additive or interactive effects of elevated ammonia, noise and low light (LL) levels on the social behaviour of growing pigs. Social behaviour was measured in terms of the nature, frequency and duration of both initiated and response behaviours for 4 weeks following mixing of the groups. General activity patterns, group cohesion and social discrimination were also examined as a function of the environmental treatments. Elevated concentrations of atmospheric ammonia (620 v .
The purpose of the study reported in this Research Communication was to evaluate alterations in concentration of total antioxidant capacity (TAC) of plasma, plasma total thiols as markers of oxidative protein damage and malondialdehyde (as a final product of lipid peroxidation) in samples obtained at different stages of the lactation cycle and dry period of dairy cows. We found that TAC was significantly lower in the primiparous cows compared to multiparous cows. This study clearly demonstrates a need for monitoring primiparous cows during the production cycle, especially when they are faced with severe metabolic conditions. Furthermore, TAC may be a sensitive, reliable and useful indicator for measurement of cumulative effects of antioxidants as an addition to metabolic profile tests, which are currently used to analyse dairy cattle health.
Zebrafish (Danio rerio) are widely used as a translational model for human neuropsychiatric conditions. Many studies have not considered sex differences in their analyses. Here, we studied sex differences of adult zebrafish in two behavioral domains: Anxiety and Memory. To assess whether sex influences anxiety-like responses, we used two different behavioral protocols, the novel tank diving task and the light-dark test. To assess sex differences in learning and memory tasks, we explored two memory domains, short-term spatial memory (free movement pattern Y-maze task) and short-term fear memory (Pavlovian fear-conditioning task). Although we did not find any significant difference in learning and memory tasks, female zebrafish showed robust increases in anxiety-like behavioral endpoints in both anxiety tests. Overall, our data suggest that zebrafish is a sensitive model to work with sex differences when modeling anxiety-related disorders and this should be an important factor to consider in different experimental designs.
•Zebrafish show aging related cognitive decline in the FMP Y-maze.•A comparison of aging zebrafish and humans reveals similar cognitive decline.•Cognitive decline in working memory in zebrafish is dopaminergic in origin.•Aging related cognitive decline in the FMP Y-maze is related to changes in dopaminergic activity. Healthy aging is associated with a decline in memory and executive function, which have both been linked with aberrant dopaminergic signaling. We examined the relationship between cognitive performance and dopamine function of young and aging zebrafish (Danio rerio). We revealed age-related decreases in working memory and cognitive flexibility in the Free-Movement Pattern (FMP) Y-maze. An increase in drd5 gene expression in aging adults coincided with a decrease in cognitive performance. Treatment with a D1/D5 receptor agonist (SKF-38393, 35 µM) 30 minutes prior to behavioral assessment resulted in improved working memory in aging zebrafish, but no effect in younger adults. However, an “overdosing” effect caused by agonist treatment resulted in downregulation of dat expression in 6-month old, treated zebrafish. The translational relevance of these findings was tested in humans by analyzing exploratory behavior in young-adult, 18-35-year olds, and aged adults, 70+ year olds, in a virtual FMP Y-maze. Our findings revealed similar age-related decline in working memory. Thus, strongly supporting zebrafish as a translational model of aging and cognitive decline.
Impulse control disorders (ICDs) are characterized by generalized difficulty controlling emotions and behaviors. ICDs are a broad group of the central nervous system (CNS) disorders including conduct disorder, intermittent explosive, oppositional-defiant disorder, antisocial personality disorder, kleptomania, pyromania and other illnesses. Although they all share a common feature (aberrant impulsivity), their pathobiology is complex and poorly understood. There are also currently no ICD-specific therapies to treat these illnesses. Animal models are a valuable tool for studying ICD pathobiology and potential therapies. The zebrafish (Danio rerio) has become a useful model organism to study CNS disorders due to high genetic and physiological homology to mammals, and sensitivity to various pharmacological and genetic manipulations. Here, we summarize experimental models of impulsivity and ICD in zebrafish and highlight their growing translational significance. We also emphasize the need for further development of zebrafish ICD models to improve our understanding of their pathogenesis and to search for novel therapeutic treatments.
Spontaneous stereotypic behaviours are repetitive, compulsive, topographically invariant response patterns commonly observed in captive or domestic animals, which have been linked to dysfunction of basal ganglia input/output pathways. There is evidence that endogenous opioids play a key regulatory role in basal ganglia direct and indirect pathways, but their precise role, both causally and functionally, in spontaneous stereotypic behaviour is unclear. Here we examined the profile of mu- and delta-opioid receptors (density [Bmax] and affinity [Kd]) of basal ganglia structures in stereotypy (n = 10) and non-stereotypy (n = 10) animals using a competitive ligand binding approach. Mu receptor densities were significantly higher in the nucleus accumbens (p
Animal behaviour is becoming increasingly popular as an endpoint in ecotoxicology due to its increased sensitivity and speed compared to traditional endpoints. However, the widespread use of animal behaviours in environmental risk assessment is currently hindered by a lack of optimisation and standardisation of behavioural assays for model species. In this study, assays to assess swimming speed were developed for a model crustacean species, the brine shrimp Artemia franciscana. Preliminary works were performed to determine optimal arena size for this species, and weather lux used in the experiments had an impact on the animals phototactic response. Swimming speed was significantly lower in the smallest arena, whilst no difference was observed between the two larger arenas, suggesting that the small arena was limiting swimming ability. No significant difference was observed in attraction to light between high and low light intensities. Arena size had a significant impact on phototaxis behaviours. Large arenas resulted in animals spending more time in the light side of the arena compared to medium and small, irrespective of light intensity. The swimming speed assay was then used to expose specimens to a range of psychotropic compounds with varying modes of action. Results indicate that swimming speed provides a valid measure of the impacts of behaviour modulating compounds on A. franciscana. The psychotropic compounds tested varied in their impacts on animal behaviour. Fluoxetine resulted in increased swimming speed as has been found in other crustacean species, whilst oxazepam, venlafaxine and amitriptyline had no significant impacts on the behaviours measured. The results from this study suggest a simple, fast, high throughput assay for A. franciscana and gains insight on the impacts of a range of psychotropic compounds on the swimming behaviours of a model crustacean species used in ecotoxicology studies.
Behavioural needs are highly motivated actions critical to a species survival and reproduction. Prolonged restriction of these behaviours can lead to stereotypic behaviours (SB) in captive animals, and this is particularly common in ungulate species. While risk factors for SB have been suggested for some ungulates, no study has integrated these findings to identify which aspects of ungulates’ wild behavioural biology and captive husbandry are potential drivers for SB across this clade. We collated SB data from 15 236 individuals across 38 ungulate species from 95 sources, and determined species wild/free-ranging behaviour from 559 additional studies. Bayesian-phylogenetic statistical methods showed that ungulate behavioural needs relating to foraging and mating are particularly affected by captive environments, with promiscuous and browsing species showing the greatest prevalence of SB. Concentrate-only diets and lack of ad libitum feed substrates were also associated with high SB prevalence. This study identifies which ungulates are better suited to captive environments and which species require targeted husbandry, enrichment and breeding protocols in order to meet their behavioural needs. Our approach of applying Bayesian-phylogenetic inference to factors influencing SB within a clade can be used to identify other intrinsic and extrinsic risk factors of reduced animal health and welfare.
Spontaneous stereotypic behaviour (SB) is common in many captive animal species, as well as in humans with some severe psychiatric disorders, and is often cited as being related to general basal ganglia dysfunction. Despite this assertion, there is little in the literature examining SB specifically in terms of the basal ganglia mechanics. In this review, we attempt to fill this gap by offering an integrative, cross-domain perspective of SB by linking what we currently understand about the SB phenotype with the ever-growing literature on the anatomy and functionality of the basal ganglia. After outlining current models of SB from different theoretical perspectives, we offer a broad but detailed overview of normally functioning basal ganglia mechanics, and attempt to link this with current neurophysiological evidence related to spontaneous SB. Based on this we present an empirically derived theoretical framework, which proposes that SB is the result of a dysfunctional action selection system that may reflect dysregulation of excitatory (direct) and inhibitory (indirect and hyperdirect) pathways as well as alterations in mechanisms of behavioural switching. This approach also suggests behaviours that specifically become stereotypic may reflect inbuilt low selection threshold behavioural sequences associated with early development and the species-specific ethogram or, low threshold behavioural sequences that are the result of stress-induced dopamine exposure at the time of performance.
Behavioural studies in ecotoxicology are increasing with techniques and endpoints used in pharmacology being translated to other vertebrate and invertebrate species. Despite this, data on the baseline behaviours of model organisms, and inter-species variability in behaviour are currently under-studied. This study assessed a range of behaviours associated with anxiety including swimming speed, phototaxis and thigmotaxis in a marine and freshwater amphipod (Echinogammarus marinas and Gammarus pulex). Differences in sensitivity to these assays were observed between species with E. marinus showing a greater sensitivity to the phototaxis assay than G. pulex, while in thigmotaxis assays G. pulex appeared better suited than E. marinus for measuring differences in the use of central zones. Significant inter-species differences were also observed in swimming patterns when breaking the data into ten second time bins but not when data was broken into two-minute time bins. The results of this study provide evidence of phototactic and thigmotactic behaviours in two model crustacean species with potential for use in behavioural ecotoxicology. Inter-species variability in sensitivity to behavioural assays highlights the importance of systematic assessment of baseline responses for all model species used in behavioural studies. Careful analysis of data is also required when performing behavioural studies so as not to lose sensitivity in your data.
Although aggression is a common symptom of psychiatric disorders the drugs available to treat it are non-specific and can have unwanted side effects. In this study we have used a behavioural platform in a phenotypic screen to identify drugs that can reduce zebrafish aggression without affecting locomotion. In a three tier screen of ninety-four drugs we discovered that caffeine and sildenafil can selectively reduce aggression. Caffeine also decreased attention and increased impulsivity in the 5-choice serial reaction time task whereas sildenafil showed the opposite effect. Imaging studies revealed that both caffeine and sildenafil are active in the zebrafish brain, with prominent activation of the thalamus and cerebellum evident. They also interact with 5-HT neurotransmitter signalling. In summary, we have demonstrated that juvenile zebrafish are a suitable model to screen for novel drugs to reduce aggression, with the potential to uncover the neural circuits and signalling pathways that mediate such behavioural effects.
Understanding the neural circuits underlying equine behaviour has the potential to help optimise strategies of husbandry and training. This review discusses two areas of neurophysiological research in a range of species and relates this information to the horse. The first discussion focuses on mechanisms of learning and motivation and assesses how this information can be applied to improve the training of the horse. The second concerns the identification of the equine neurophysiological phenotype, through behavioural and genetic probes, as a way of improving strategies for optimal equine husbandry and training success. The review finishes by identifying directions for future research with an emphasis on how neurophysiological systems (and thus behaviour) can be modified through strategic husbandry. This review highlights how a neurophysioloigical understanding of horse behaviour can play an important role in attaining the primary objectives of equitation science as well as improving the welfare of the horse.
•Major increase in understanding of aquatic vertebrate behaviour will benefit toxicologists wishing to link behaviour and physiology.•Caution must be taken to ensure reliability and validity of tests being developed if data are to be useful.•This review makes some suggestions and recommendations that may help to improve this field as it begins to emerge. Current advances in the ability to assay adult aquatic vertebrate behaviour are potentially very useful to aquatic toxicologists wishing to characterise the effects of pollutants on behaviour, cognition or neurodevelopment. This review considers two specific challenges faced by researchers wishing to exploit these technologies: maximising reliability and validity. It will suggest two behavioural procedures, with the potential for automation and high-throughput implementation, which can be used to measure social cohesion and anxiety, two areas of interest in behavioural aquatic toxicology. In addition, the review will make recommendations about how these procedures (and others) could be carried out to maximise reliability and validity.
The use of behaviour in ecotoxicology is expanding, however the lack of standardisation and validation of these assays currently presents a major drawback in moving forward in the development of behavioural assays. Furthermore, there is a current paucity of control data on test species, particularly invertebrate models. In this study we assessed a range of behaviours associated with spatial distribution and locomotion in relation to arena size and shape in two species of amphipod crustacean ( Echinogammarus marinus and Gammarus pulex ). Arena shape had significant effects on almost all behavioural parameters analysed. Increasing arena size resulted in an increased mean velocity and activity plus increased proportional use of the central zones. These results indicate that ‘ceiling effects’ may occur in some ecotoxicological studies resulting in potentially ‘false’ negative effects if careful consideration is not paid to experimental design. Differences in behaviours were observed between the two species of amphipod. For example, G. pulex spend approximately five times (∼20%) more of the available time crossing the central zones of the arenas compared to E. marinus (∼4%) which could have implications on assessing anxiolytic behaviours. The results of this study highlight several behaviours with potential for use in behavioural ecotoxicology with crustaceans but also underscore the need for careful consideration when designing these behavioural assays.
Neurodevelopmental disorders (NDDs) caused by aberrant brain growth and development are life-long, debilitating illnesses that markedly impair the quality of life. Animal models are a valuable tool for studying NDD pathobiology and therapies. Mounting evidence suggests the zebrafish (Danio rerio) as a useful model organism to study NDDs, possessing both high physiological homology to humans and sensitivity to pharmacological and genetic manipulations. Here, we summarize experimental models of NDDs in zebrafish and highlight the growing translational significance of zebrafish NDD-related phenotypes. We also emphasize the need in further development of zebrafish models of NDDs to improve our understanding of their pathogenesis and therapeutic treatments. This article is part of a Special Issue entitled: Animal Models of Neurodevelopmental Disorders. (C) 2020 IBRO. Published by Elsevier Ltd. All rights reserved.
A relationship between dopamine and temperament has previously been described in human cases of dopaminergic dysfunction. Adjustment in temperament prior to disease manifestation can enable the early identification of individuals at risk of such conditions, and scope exists to extend this application of temperament alterations to cases of dopaminergic dysfunction in horses. A multivariate and mixed-methods approach utilising a questionnaire along with two inferred measurements of dopamine activity (Spontaneous Blink Rate [SBR] and behavioral initiation rate [BIRD were recorded from direct observation of animals (n = 99) to identify the potential relationship between dopamine and temperament in horses. Principal components analysis (PCA) of 36 temperament variables revealed nine principal components, including 'Anxiety' and 'Docility', which accounted for 72.4% of the total variance. Component scores were calculated and correlated with SBR and BIR utilising Spearman rank correlation coefficient analysis. The component 'Anxiety' was found to have a significant positive relationship with SBR, whereas 'Docility' was observed to have a significant negative relationship with SBR. These results indicate a relationship between dopamine and temperament within the horse that is certainly worthy of further study. Potential mechanisms involving neural dopaminergic and GABAergic systems are presented, in addition to how such alterations could be utilised to probe for equine dopamine dysfunction pending future research. (C) 2016 Elsevier Inc. All rights reserved.
Whilst it is recognized that contraction plays an important part in maintaining the structure and function of mature skeletal muscle, its role during development remains undefined. In this study the role of movement in skeletal muscle maturation was investigated in intact zebrafish embryos using a combination of genetic and pharmacological approaches. An immotile mutant line (cacnb1(ts25)) which lacks functional voltage-gated calcium channels (dihydropyridine receptors) in the muscle and pharmacological immobilization of embryos with a reversible anesthetic (Tricaine), allowed the study of paralysis (in mutants and anesthetized fish) and recovery of movement (reversal of anesthetic treatment). The effect of paralysis in early embryos (aged between 17 and 24 hours post-fertilization, hpf) on skeletal muscle structure at both myofibrillar and myofilament level was determined using both immunostaining with confocal microscopy and small angle X-ray diffraction. The consequences of paralysis and subsequent recovery on the localization of the actin capping proteins Tropomodulin 1 & 4 (Tmod) in fish aged from 17 hpf until 42 hpf was also assessed. The functional consequences of early paralysis were investigated by examining the mechanical properties of the larval muscle. The length-force relationship, active and passive tension, was measured in immotile, recovered and control skeletal muscle at 5 and 7 day post fertilization (dpf). Recovery of muscle function was also assessed by examining swimming patterns in recovered and control fish. Inhibition of the initial embryonic movements (up to 24 hpf) resulted in an increase in myofibril length and a decrease in width followed by almost complete recovery in both moving and paralyzed fish by 42 hpf. In conclusion, myofibril organization is regulated by a dual mechanism involving movement-dependent and movement-independent processes. The initial contractile event itself drives the localization of Tmod1 to its sarcomeric position, capping the actin pointed ends and ultimately regulating actin length. This study demonstrates that both contraction and contractile independent mechanisms are important for the regulation of myofibril organization, which in turn is necessary for establishing proper skeletal muscle structure and function during development in vivo in zebrafish.
•Sex is an important biological variable in translational neuroscience research.•There are overt sex differences in clinical and preclinical alcohol research.•The use of zebrafish (Danio rerio) in pre-clinical alcohol research rapidly grows.•Here, we discuss zebrafish models to study sex differences in alcohol brain action. Sex is an important biological variable that is widely recognized in studies of alcohol-related effects. Complementing clinical and preclinical rodent research, the zebrafish (Danio rerio) is the second most used laboratory species, and a powerful model organism in biomedicine. Like clinical and rodent models, zebrafish demonstrate overt sex differences in alcohol-related responses. Collectively, this evidence shows that the zebrafish becomes a sensitive model species to further probe in-depth sex differences commonly reported in alcohol research.
Introduction: Neurodevelopmental disorders (NDDs) are common and severely debilitating. Their chronic nature and reliance on both genetic and environmental factors makes studying NDDs and their treatment a challenging task. Areas covered: Herein, the authors discuss the neurobiological mechanisms of NDDs, and present recommendations on their translational research and therapy, outlined by the International Stress and Behavior Society. Various drugs currently prescribed to treat NDDs also represent a highly diverse group. Acting on various neurotransmitter and physiological systems, these drugs often lack specificity of action, and are commonly used to treat multiple other psychiatric conditions. There has also been relatively little progress in the development of novel medications to treat NDDs. Based on clinical, preclinical and translational models of NDDs, our recommendations cover a wide range of methodological approaches and conceptual strategies. Expert opinion: To improve pharmacotherapy and drug discovery for NDDs, we need a stronger emphasis on targeting multiple endophenotypes, a better dissection of genetic/epigenetic factors or "hidden heritability," and a careful consideration of potential developmental/trophic roles of brain neurotransmitters. The validity of animal NDD models can be improved through discovery of novel (behavioral, physiological and neuroimaging) biomarkers, applying proper environmental enrichment, widening the spectrum of model organisms, targeting developmental trajectories of NDD-related behaviors and comorbid conditions beyond traditional NDDs. While these recommendations cannot be addressed all in once, our increased understanding of NDD pathobiology may trigger innovative cross-disciplinary research expanding beyond traditional methods and concepts.
•Social interactions are essential for health and wellbeing across species.•Zebrafish are a prominent model to investigate the importance of social interactions.•Lack of social interaction and social isolation have negative behavioral and physiologic effects on zebrafish.•Advantages and limitations of using zebrafish to understand social behavior were discussed. Social behavior represents a beneficial interaction between conspecifics that is critical for maintaining health and wellbeing. Dysfunctional or poor social interaction are associated with increased risk of physical (e.g., vascular) and psychiatric disorders (e.g., anxiety, depression, and substance abuse). Although the impact of negative and positive social interactions is well-studied, their underlying mechanisms remain poorly understood. Zebrafish have well-characterized social behavior phenotypes, high genetic homology with humans, relative experimental simplicity and the potential for high-throughput screens. Here, we discuss the use of zebrafish as a candidate model organism for studying the fundamental mechanisms underlying social interactions, as well as potential impacts of social isolation on human health and wellbeing. Overall, the growing utility of zebrafish models may improve our understanding of how the presence and absence of social interactions can differentially modulate various molecular and physiological biomarkers, as well as a wide range of other behaviors.
Crib biting is a common equine stereotypic behavior that has links to health problems and poor welfare. There is evidence that crib biters may be more sensitive to environmental stressors, and the aim of the present study was to test the hypothesis that crib-biting behavior in horses has a relationship with oxidative stress, antioxidant defense, or inflammatory proteins, as is observed in humans with various affective disorders such as depression and anxiety. Ten crib-biting horses and 10 age- and sex-matched healthy horses were used. Vital signs (heart rates, respiratory rates, and temperature) and blood samples were taken in 3 conditions; basal condition for crib biters (no stereotypic behavior observed for at least 30 minutes); crib biters during or directly after crib-biting periods (“acute crib biting” = crib biting for at least 15 minutes with no interruption longer than 2 minutes); non–crib-biting horses (control). Comparisons were made between crib biters and controls, and between crib-biters' basal and crib-biting values. No changes were observed in the vital signs. Total antioxidant capacity activity was significantly decreased in crib biters during the basal measurements relative to controls, and this was significantly decreased again during an episode of crib biting. Similar differences to those observed in total antioxidant capacity were also observed for the antioxidant enzymes superoxide dismutase, glutathione peroxidase, and catalase. Collectively, our data suggest that the antioxidant levels and antioxidant defenses against lipid peroxidation are reduced in crib biters, suggesting that oxidative stress plays a role in the pathophysiology of crib biting. In addition, our data suggest that further study on the role of oxidative stress in crib biting might be of benefit, particularly in the search for veterinary treatments or interventions for crib-biting horses.
Reductions in measures of dendritic morphology in the agranular insular cortex have been identified as consequences of prenatal exposure to moderate levels of ethanol in the rat. Motivated by the strong connectivity between this region of frontal cortex and the striatum and a growing body of data linking specific components of the mesocortical/limbic system to effects of ethanol and ethanol self-administration, the current study investigated the effects of moderate fetal ethanol exposure on the dendritic morphology of medium spiny neurons (MSNs) in several regions of the striatum. Throughout gestation, pregnant rat dams either consumed a saccharin solution (control) or achieved average daily blood ethanol concentrations of 84 mg% via voluntary consumption of a 5% ethanol solution. The brains of adult male offspring were extracted and processed for Golgi-Cox staining. MSNs from the dorsomedial striatum, dorsolateral striatum and the nucleus accumbens core and shell were sampled for analysis. Relative to saccharin controls, robust reductions in dendritic length and branching, but not spine density, were observed in the shell of the nucleus accumbens in fetal-ethanol-exposed rats. No significant prenatal ethanol effects were found in the other regions of the striatum. These findings suggest that exposure to moderate levels of ethanol in utero can have profound effects on brain regions related to reward processing and provide possible clues relevant to understanding increased self-administration of drugs of abuse in animals exposed to ethanol during brain development. (c) 2012 Elsevier Inc. All rights reserved.
An online survey of domestic horse breeders in the USA, UK, Australia, Canada and mainland Europe was carried out in order to examine management risk factors associated with the development of abnormal behaviour patterns. One hundred and forty breeders responded, and epidemiological results suggested that the overall number of horses showing abnormal behaviours may be declining (5.2% of the sample). However, as found in previous studies, extensive, as opposed to intensive management practices reduce the risk of foals developing abnormal behaviours. In addition, offering foals low-energy forage in higher quantities reduces the risk of abnormal behaviour (P < 0.001). Results are discussed in relation to previous surveys, and suggestions are made for breeders and owners to help reduce the risks of young horses developing abnormal behaviours associated with weaning practices. (C) 2008 Elsevier B.V. All rights reserved.
The damaging effects of alcohol on a developing fetus are well known and cause a range of conditions known as fetal alcohol spectrum disorder (FASD). High levels of alcohol exposure lead to physical deformity and severe cognitive deficits, but more moderate exposure leads to a range of subtle cognitive effects such as reduced social behavior, higher propensity to develop addictions, and reduced spatial working memory. Previous studies have demonstrated that following exposure to relatively low levels of ethanol during early brain development (equivalent in humans to moderate exposure) zebrafish display a range of social and behavioral differences. Here, our aim was to test the hypothesis that moderate developmental ethanol exposure would affect aspects of learning and memory in zebrafish. In order to do this, we exposed zebrafish embryos to 20 mM [0.12% v/v] ethanol from 2 to 9 dpf to model the effects of moderate prenatal ethanol (MPE) exposure. At 3 months old, adult fish were tested for appetitive and aversive learning, and for spatial alternation in a novel unconditioned y-maze protocol. We found that MPE did not affect appetitive or aversive learning, but exposed-fish showed a robust reduction in repetitive alternations in the y-maze when compared to age matched controls. This study confirms that moderate levels of ethanol exposure to developing embryos have subtle effects on spatial working memory in adulthood. Our data thus suggest that zebrafish may be a promising model system for studying the effects of alcohol on learning and decision-making, but also for developing treatments and interventions to reduce the negative effects of prenatal alcohol.
Stereotypic behaviors are commonly observed in domestic equids as they are in a range of captive nondomesticated species. Estimates suggest that 19.5%-32.5% of horses perform a stereotypy. The presence of these behaviors is thought to indicate suboptimal welfare status and can result in secondary physical pathologies, such as colic, ligament strain, and incisor wear. Relatively little is understood about the etiologies of oral and locomotor stereotypies. Seemingly disparate causal factors have been proposed, including gastric pathology, neural adaptation, and genetic predisposition. In this review, we propose a model of causality that presents separate pathways to the development and continuation of oral behaviors such as crib-biting, compared with locomotor alternatives (i.e., weaving). The word stereotypy has alarmingly negative connotation among horse keepers. Stereotypic behaviors are often viewed as vices, and therefore, a number of horse owners and establishments attempt to physically prevent the behavior with harsh mechanical devices. Such interventions can result in chronic stress and be further detrimental to equine welfare. Stereotypy has been proposed to be a stress coping mechanism. However, firm evidence of coping function has proven elusive. This review will explore management options directed at both prophylaxis and remediation.
In three experiments, we examined whether overshadowing of geometric cues by a discrete landmark (beacon) is due to the relative saliences of the cues. Using a virtual water maze task, human participants were required to locate a platform marked by a beacon in a distinctively shaped pool. In Experiment 1, the beacon overshadowed geometric cues in a trapezium, but not in an isosceles triangle. The longer escape latencies during acquisition in the trapezium control group with no beacon suggest that the geometric cues in the trapezium were less salient than those in the triangle. In Experiment 2, we evaluated whether generalization decrement, caused by the removal of the beacon at test, could account for overshadowing. An additional beacon was placed in an alternative corner. For the control groups, the beacons were identical; for the overshadow groups, they were visually unique. Overshadowing was again found in the trapezium. In Experiment 3, we tested whether the absence of overshadowing in the triangle was due to the geometric cues being more salient than the beacon. Following training, the beacon was relocated to a different corner. Participants approached the beacon rather than the trained platform corner, suggesting that the beacon was more salient. These results suggest that associative processes do not fully explain cue competition in the spatial domain.
Retinal dystrophies are a heterogeneous group of disorders of visual function leading to partial or complete blindness. We report the genetic basis of an unusual retinal dystrophy in five families with affected females and no affected males. Heterozygous missense variants were identified in the X‐linked phosphoribosyl pyrophosphate synthetase 1 (PRPS1) gene: c.47C > T, p.(Ser16Phe); c.586C > T, p.(Arg196Trp); c.641G > C, p.(Arg214Pro); and c.640C > T, p.(Arg214Trp). Missense variants in PRPS1 are usually associated with disease in male patients, including Arts syndrome, Charcot–Marie–Tooth, and nonsyndromic sensorineural deafness. In our study families, affected females manifested a retinal dystrophy with interocular asymmetry. Three unrelated females from these families had hearing loss leading to a diagnosis of Usher syndrome. Other neurological manifestations were also observed in three individuals. Our data highlight the unexpected X‐linked inheritance of retinal degeneration in females caused by variants in PRPS1 and suggest that tissue‐specific skewed X‐inactivation or variable levels of pyrophosphate synthetase‐1 deficiency are the underlying mechanism(s). We speculate that the absence of affected males in the study families suggests that some variants may be male embryonic lethal when inherited in the hemizygous state. The unbiased nature of next‐generation sequencing enables all possible modes of inheritance to be considered for association of gene variants with novel phenotypic presentation. We report the genetic basis of an unusual retinal dystrophy with inter‐ocular asymmetry in families with only affected females. Heterozygous missense variants were identified in the X‐linked PRPS1 gene. PRPS1 missense variants are usually associated with disease in males, including Arts Syndrome and Charcot‐Marie‐Tooth. The unexpected X‐linked inheritance suggests tissue specific skewed X‐inactivation or variable levels of PRS‐I deficiency are the underlying mechanism(s). The absence of affected males in these families suggests that some PRPS1 variants may be male lethal.
•Neurodevelopmental disorders (NDDs) are severely debilitating neuropsychiatric illnesses.•NDDs are caused by aberrant brain development, and have strong genetic causes and risk factors.•NDDs are also modulated by various environmental factors, and can be modeled experimentally.•Animal models are a valuable tool to mimic a wide spectrum of NDDs and related conditions.•Here, we discuss the neurobiological mechanisms of selected NDDs and their experimental models. Neurodevelopmental disorders (NDDs) are a heterogeneous group of prevalent neuropsychiatric illnesses with various degrees of social, cognitive, motor, language and affective deficits. NDDs are caused by aberrant brain development due to genetic and environmental perturbations. Common NDDs include autism spectrum disorder (ASD), intellectual disability, communication/speech disorders, motor/tic disorders and attention deficit hyperactivity disorder. Genetic and epigenetic/environmental factors play a key role in these NDDs with significant societal impact. Given the lack of their efficient therapies, it is important to gain further translational insights into the pathobiology of NDDs. To address these challenges, the International Stress and Behavior Society (ISBS) has established the Strategic Task Force on NDDs. Summarizing the Panel’s findings, here we discuss the neurobiological mechanisms of selected common NDDs and a wider NDD+ spectrum of associated neuropsychiatric disorders with developmental trajectories. We also outline the utility of existing preclinical (animal) models for building translational and cross-diagnostic bridges to improve our understanding of various NDDs.
Adolescents are the next generation of consumers with the potential to raise standards of farm animal welfare to their satisfaction if their preferences and concerns are translated into accurate market drivers and signals. There are no published data about adolescent views of farm animal welfare to allow meaningful design, implementation, and evaluation of educational strategies to improve consideration of and behavior toward farm animals. Knowledge of farm animal welfare, as well as beliefs and attitudes about farm animal welfare and behavioral intention relevant to it were determined in a sample of UK adolescents, using a survey incorporating an extended version of the theory of planned behavior and novel assessment tools. Our results indicate that adolescents have only a limited knowledge of welfare problems for farm animals and welfare-relevant product labels. Intentions to identify welfare standards for the animals from whom their food was derived were weak. Although they cared about farm animal welfare and agreed with fundamental principles for example, the provision of space and the absence of pain and suffering like adults they held limited belief in the power and responsibility that they possess through their choices as consumers; responsibility was often shifted to others, such as the government and farmers.
Background: Large animal models of human neurological disorders are advantageous compared to rodent models due to their neuroanatomical complexity, longevity and their ability to be maintained in naturalised environments. Some large animal models spontaneously develop behaviours that closely resemble the symptoms of neural and psychiatric disorders. The horse is an example of this; the domestic form of this species consistently develops spontaneous stereotypic behaviours akin to the compulsive and impulsive behaviours observed in human neurological disorders such as Tourette's syndrome. The ability to non-invasively probe normal and abnormal equine brain function through cognitive testing may provide an extremely useful methodological tool to assess brain changes associated with certain human neurological and psychiatric conditions. New method: An automated operant system with the ability to present visual and auditory stimuli as well as dispense salient food reward was developed. To validate the system, ten horses were trained and tested using a standard cognitive task (three choice serial reaction time task (3-CSRTT)). Results: All animals achieved total learning criterion and performed six probe sessions. Learning criterion was met within 16.30 +/- 0.79 sessions over a three day period. During six probe sessions, level of performance was maintained at 80.67 +/- 0.57% (mean +/- SEM) accuracy. Comparison with existing method(s): This is the first mobile fully automated system developed to examine cognitive function in the horse. Conclusions: A fully-automated operant system for mobile cognitive function of a large animal model has been designed and validated. Horses pose an interesting complementary model to rodents for the examination of human neurological dysfunction. 2017 Elsevier B.V. All rights reserved.
The present two studies aimed to look at alternative methods of assaying the changes underpinning drug consumption and dependence. Here, we focus on whether olfactory differences exist in habitual consumers in the form of recognition and sensitivity tasks to a caffeine-related odor. In Experiment 1, high ( = 18), moderate ( = 23), and non-consumers ( = 21) of caffeine completed a threshold test for a coffee odor, followed by a recognition test for both a coffee and a neutral odor and, finally, a measure of caffeine craving. In Experiment 2, 16 consumers and 16 non-consumers completed threshold tests for two odors, coffee and control (n-butanol), followed by a caffeine-related implicit association test. In Experiment 1, recognition of the coffee odor was faster for caffeine consumers versus non-consumers. We also found that high-caffeine consumers had greater olfactory sensitivity for the coffee odor compared to the other groups, which was related to craving. In Experiment 2, we again found greater sensitivity for the coffee odor in consumers but no differences between groups for the control odor. Additionally, craving was greater in consumers who had just been exposed to the coffee odor. These findings provide evidence for the first time that regular consumers of coffee have enhanced sensitivity to an odor associated with caffeine. They further suggest that drug-associated odors could be a useful tool in furthering theory in drug dependence. (PsycInfo Database Record (c) 2020 APA, all rights reserved).
Introduction: Depression is a highly debilitating psychiatric disorder that affects the global population and causes severe disabilities and suicide. Depression pathogenesis remains poorly understood, and the disorder is often treatment-resistant and recurrent, necessitating the development of novel therapies, models and concepts in this field. Areas covered: Animal models are indispensable for translational biological psychiatry, and markedly advance the study of depression. Novel approaches continuously emerge that may help untangle the disorder heterogeneity and unclear categories of disease classification systems. Some of these approaches include widening the spectrum of model species used for translational research, using a broader range of test paradigms, exploring new pathogenic pathways and biomarkers, and focusing more closely on processes beyond neural cells (e.g. glial, inflammatory and metabolic deficits). Expert opinion: Dividing the core symptoms into easily translatable, evolutionarily conserved phenotypes is an effective way to reevaluate current depression modeling. Conceptually novel approaches based on the endophenotype paradigm, cross-species trait genetics and 'domain interplay concept', as well as using a wider spectrum of model organisms and target systems will enhance experimental modeling of depression and antidepressant drug discovery.
Crib-biting is a repetitive and compulsive behavior that is characterized by “grasping a fixed object with incisor teeth and aspirating air with an audible grunt.” Little is known about etiology and pathophysiology of crib-biting behavior in horses. Previously, we have shown that oxidative stress is linked to crib-biting, with crib-biters showing lower antioxidant capacity than non–crib-biting horses. The aim of the present study was to extend our understanding of oxidative stress in crib-biting to determine the serum contents of some mineral trace elements (manganese [Mn], magnesium [Mg], selenium [Se], copper [Cu], and zinc [Zn]), and electrolytes (sodium [Na], potassium [K], calcium [Ca], and phosphorus [P]). Also, the activity of enzymes (alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and gamma glutamyl transferase), some hormones (cortisol, ghrelin, β-endorphin, and serotonin) and blood biochemistry values of various parameters was measured to evaluate their possible association with crib-biting behavior in horses. Blood samples were taken from all horses under the following conditions: basal conditions of crib-biting horses, during or immediately after crib-biting periods, and from non–crib-biting, healthy horses (control group). Serum Se concentration was significantly lower (P ≤ 0.001) in crib-biting horses than in controls, with the lowest levels seen during crib-biting behavior. Other measured parameters did not differ between acute crib-biting horses and healthy controls. These observations suggest that alterations in serum Se, an important component of the antioxidant system, may play a role in the pathophysiology of crib-biting behavior in horses, adding further evidence to the theory that crib-biting may be related to increased oxidative stress and alterations in essential trace elements.
Horses displaying an oral stereotypy were tested on an instrumental choice paradigm to examine differences in learning from non-stereotypic counterparts. Stereotypic horses are known to have dysfunction of the dorsomedial striatum, and lesion studies have shown that this region may mediate response-outcome learning. The paradigm was specifically applied in order to examine learning that requires maintenance of response-outcome judgements. The non-stereotypic horses learned, over three sessions, to choose a more immediate reinforcer, whereas the stereotypic horses failed to do so. This suggests an initial behavioural correlate for dorsomedial striatum dysregulation in the stereotypy phenotype. (C) 2008 Elsevier B.V. All rights reserved.
Neurodevelopmental disorders (NDDs) are highly prevalent and severely debilitating brain illnesses caused by aberrant brain growth and development. Resulting in cognitive, social, motor, language and affective disabilities, common NDDs include autism spectrum disorder (ASD), intellectual disability, communication/speech disorders, motor/tic disorders and attention deficit hyperactivity disorder. Affecting neurogenesis, glia/neuronal proliferation and migration, synapse formation and myelination, aberrant neural development occurs over a substantial period of time. Genetic, epigenetic, and environmental factors play a key role in NDD pathogenesis. Animal models are an indispensable tool to study NDDs. Paralleling clinical findings, we comprehensively evaluate various preclinical tests and models which target key (social, cognitive, motor) neurobehavioral domains of ASD and other common NDDs. Covering both traditional (rodent) and alternative NDD models, we outline the emerging areas of research and emphasize how preclinical models play a key role in gaining translational and mechanistic insights into NDDs and their therapy.
GRIA1 encodes the GluA1 subunit of α-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) receptors, which are ligand-gated ion channels that act as excitatory receptors for the neurotransmitter L -glutamate (Glu). AMPA receptors (AMPARs) are homo- or heteromeric protein complexes with four subunits, each encoded by different genes, GRIA1 to GRIA4 . Although GluA1-containing AMPARs have a crucial role in brain function, the human phenotype associated with deleterious GRIA1 sequence variants has not been established. Subjects with de novo missense and nonsense GRIA1 variants were identified through international collaboration. Detailed phenotypic and genetic assessments of the subjects were carried out and the pathogenicity of the variants was evaluated in vitro to characterize changes in AMPAR function and expression. In addition, two Xenopus gria1 CRISPR-Cas9 F 0 models were established to characterize the in vivo consequences. Seven unrelated individuals with rare GRIA1 variants were identified. One individual carried a homozygous nonsense variant (p.Arg377Ter), and six had heterozygous missense variations (p.Arg345Gln, p.Ala636Thr, p.Ile627Thr, and p.Gly745Asp), of which the p.Ala636Thr variant was recurrent in three individuals. The cohort revealed subjects to have a recurrent neurodevelopmental disorder mostly affecting cognition and speech. Functional evaluation of major GluA1-containing AMPAR subtypes carrying the GRIA1 variant mutations showed that three of the four missense variants profoundly perturb receptor function. The homozygous stop-gain variant completely destroys the expression of GluA1-containing AMPARs. The Xenopus gria1 models show transient motor deficits, an intermittent seizure phenotype, and a significant impairment to working memory in mutants. These data support a developmental disorder caused by both heterozygous and homozygous variants in GRIA1 affecting AMPAR function.
RationaleChronic alcohol misuse can escalate into alcohol use disorder (AUD). The causal mechanisms through which recreational social drinking develops into compulsive uncontrolled alcohol misuse are multifaceted. For example, stress is an important risk factor that influences alcohol craving in both healthy and addicted individuals. In addition, those that are high in impulsivity/risk taking drink more and are at greater risk of developing addiction. At present, however, it is not possible accurately to predict those at risk of escalation in alcohol use, or of developing AUD.ObjectivesThe aim of this study was to investigate how underlying physiological and personality traits affect stress-induced craving for, and consumption of, alcohol, in a sample of social drinkers. The primary hypothesis was that impulsivity/risk-taking would modulate stress-induced alcohol craving and consumption.MethodsThirty-nine participants (22 male and 17 female; mean age=23.92years [SD=4.90]) were randomly allocated to stress' and no-stress' groups; in the stress group, participants took part in the Trier Social Stress Test (TSST). Participants completed several questionnaires and computer tasks in order to assess prior alcohol use, impulsivity/risk-taking, stress-reactivity, craving and physiological biomarkers of stress. Finally, participants completed a voluntary drinking task, in which increasing numbers of presses on a computer keyboard were reinforced with 5-ml shots of 37% ABV vodka (plus mixer).ResultsParticipants exposed to the TSST showed an increase in craving following the stressor. Several factors predicted voluntary drinking, including risky decision making, slow HR recovery from stress, poor vagal tone during recovery from stress and greater stress reactivity. Surprisingly, we found no correlation between craving and consumption.ConclusionsOur data suggest that variation in physiological stress parameters and poor decision-making abilities increase risk of stress-induced alcohol consumption. This may provide a useful translational framework through which we can further study early predictive markers for the shift between controlled recreational drinking to uncontrolled alcohol misuse, including AUD.
Background: We aimed to assess whether stress, boredom, drinking motives, and/or inhibitory control were related to alcohol use during a period of social isolation. Method: Analyses were carried out on questionnaire data (N = 337) collected during the first wave of the COVID-19 pandemic (7 April-3 May 2020). We first assessed changes in drinking behavior, stress and boredom. We then regressed drinking behavior on drinking motives, inhibitory control, stress, and boredom. We also investigated interactions between change in stress/boredom and inhibitory control. Results: A minority of respondents reported increased alcohol use (units = 23.52%, drinking days = 20.73%, heavy days = 7.06%), alcohol-related problems (9.67%), and stress (36.63%). Meanwhile, most respondents reported increased boredom (67.42%). Similarly, boredom significantly increased (B = 21.22, p < .001), on average, while alcohol-related problems decreased (B = -1.43 p < .001). Regarding drinking motives, decreased alcohol-related problems were associated with social drinking motives (B = -0.09, p = .005). Surprisingly, risk-taking was associated with decreased alcohol-related problems (B = -0.02, p = .008) and neither stress nor boredom independently predicted changes in alcohol use. Finally, several significant interactions suggested that those who were more impulsive and less bored were more likely to report increased alcohol use and vice versa. Conclusions: These data provide a nuanced overview of changes in drinking-related behavior during the COVID-19-induced period of social isolation. While most people reduced their drinking, there was evidence of complex interactions between impulsivity and boredom that may be explored in future studies.
Background: Exposure to stress and trait impulsivity are independent predictors of relapse in recovering alcoholics, but potential mechanisms that link these two risk-factors in terms of their putative additive or interactive contributions to relapse are not known. The aim of this study was to use a model of stress-induced relapse to test the hypothesis that acute psychosocial stress increases craving for alcohol in social drinkers. We also tested the hypothesis that change in craving could be explained by variability in impulsivity and risk-taking. Methods: Participants completed questionnaires to assess drinking behaviour (Alcohol Dependence Questionnaire [ADQ]; and an Alcohol Use Disorders Identification Test [AUDIT]), craving (Desires for Alcohol Questionnaire [DAQ] and impulsivity (Barrett Impulsiveness Scale [BIS]). Participants also completed two computer tasks to assess risk-taking and impulsivity, the Balloon Analogue Risk Test (BART) and a continuous performance task (CPT). Participants then underwent the Trier Social Stress Test (TSST), and completed a final DAQ to assess post-stress craving. Results: Participants showed an increase in craving following exposure to the TSST. In addition, risk-taking was positively correlated with change in craving. Conclusions: Our data suggests that acute psychosocial stress increases subjective craving in social drinkers, but that the effects may be trait-dependent, with stress-induced increases in craving correlated with risk-taking.
We explored (1) self-reported changes in alcohol use during the pandemic in the UK and (2) the extent to which self-reported inhibitory control and/or stress were associated with any change in drinking behaviour. We used a UK-based cross-sectional online survey administered to four nationally representative birth cohorts (N = 13,453). A significant minority of 30- (29.08%) and 50-year-olds (26.67%) reported drinking more, and between 32.23 and 45.02% of respondents reported feeling more stressed depending on the cohort. Stress was associated with hazardous drinking among 30-year-olds (OR = 3.77, 95% CI 1.15 to 12.28). Impatience was associated with both increased alcohol use (1.14, 95% CI 1.06, 1.24) and hazardous drinking (1.20, 95% CI 1.05, 1.38) among 19-year-olds. Risk-taking was associated with hazardous drinking for 30-year-olds (OR = 1.18, 95% CI 1.05, 1.32). These data highlight concerns for those at risk of alcohol misuse and alcohol-related harm during COVID-19 lockdowns.
Exposure to anesthetic drugs is common in biomedical sciences being part of routine procedures in different translational species, however its impacts on memory and cognition are still debated, having different impacts depending on drug and age. The zebrafish (Danio rerio) is a translational species widely used in behavioral neuroscience, where tricaine methanesulfonate (MS222) is the most acceptable and used drug when conducting routine procedures. Based on this, we investigated the effects of MS222 (100 mg/l) in young adults and aging zebrafish 1, 2, 3, and 7 days after exposure. Animals' were submitted to the anesthetic procedure until loss of body posture, slowing of opercular movements and lack of response to tail touch with a plastic pipette were achieved, then further left in the drug for 3 min. After that, animals (6 mpf vs. 24 mpf) were transferred to a recovery tank until fully recovered and transferred back to their housing system until further testing in the free movement pattern (FMP) Y-maze, which assesses zebrafish working memory and cognitive lexibility. Young animals had significant impairment in their working memory and cognitive flexibility 1 and 2 days after the exposure to MS222, being fully recovered by day 3 and with no effects 7 days post drug exposure. Increased repetitions were also observed for animals exposed to MS222 which could indicate increased stress-related response in animals up to 2 days after drug exposure. No drug effect was observed in aging animals besides their natural decreased alternations and working memory. Overall, behavioral experiments after routine procedures using MS222 should be performed with caution and need to be delayed, at least 3 days after exposure where working memory, cognitive flexibility, and repetitive behavior are back to normal.
Triangulation of approaches (i.e., using several tests of the same construct) can be extremely useful for increasing the robustness of the findings being widely used when working with behavioral testing, especially when using rodents as a translational model. Although zebrafish are widely used in neuropharmacology research due to their high-throughput screening potential for new therapeutic drugs, behavioral test battery effects following pharmacological manipulations are still unknown. Here, we tested the effects of an anxiety test battery and test time following pharmacological manipulations in zebrafish by using two behavioral tasks: the novel tank diving task (NTT) and the light-dark test (LDT). Fluoxetine and conspecific alarm substance (CAS) were chosen to induce anxiolytic and anxiogenic-like behavior, respectively. For non-drug-treated animals, no differences were observed for testing order (NTT → LDT or LDT → NTT) and there was a strong correlation between performances on the two behavioral tasks. However, we found that during drug treatment, NTT/LDT responses are affected by the tested order depending on the test time being fluoxetine effects higher at the second behavioral task (6 min later) and CAS effects lower across time. Overall, our data supports the use of baseline behavior assessment using this anxiety test battery. However, when working with drug exposure, data analysis must carefully consider time-drug-response and data variability across behavioral tasks.
There has been rapid growth in the use of larval zebrafish as a complementary vertebrate model for drug discovery, abuse liability and pharmacological toxicology, resulting in a huge increase in zebrafish facilities worldwide. However, many research groups working with zebrafish do not typically report the pH of husbandry conditions in methodologies, nor are the pH of drug treatments reported in many research articles. This unknown factor can be a major contributor in the differential effects of drug treatments. Therefore, as a case study, we tested the impact of altering pH of several drugs of abuse and assessed locomotor changes associated with a single drug concentration delivered at different pHs. We found that a change of a single pH unit, within the pH ranges commonly used in zebrafish husbandry, was enough to alter locomotor activity at a fixed drug concentration. Many pharmacological agents are dependent on environmental factors, such as pH, to determine bioavailability. Efficaciousness for many classes of drug is dependent on their ionization state in which shifts towards uncharged species can influence the easy of a drug crossing biological membranes. Thus, we urge users to report pH in husbandry methods and drug treatments to improve replicability and inter-study comparisons.
Zebrafish are growing in use as a model for understanding drug dependence and addiction. Sensitization paradigms have been a useful tool in identifying mechanisms involved in drug-induced behavioral and neurological changes, but in zebrafish have tended to focus on locomotor, rather than cognitive, endpoints. Here, we used a novel method, the FMP Y-maze, which measures continuous performance through a series of repeated binary choices (L vs R), to establish a model for assessing parameters associated with psychostimulant-induced behavioral and cognitive sensitization in adult zebrafish. Repeat, intermittent exposure to d-amphetamine (AMPH) for 14 days increased alternations (LRLR) in the maze, suggesting improved working memory, which was enhanced further following drug challenge after a short withdrawal period, suggesting behavioral sensitization. However, this cognitive enhancement coincided with a reduction in the use of other exploration strategies, hypolocomotion, and inhibition of cognitive flexibility. Like AMPH, exposure to nicotine (NIC) increased alternations following drug challenge after chronic treatment. Repeat NIC exposure appeared to induce both cognitive and psychomotor sensitization, as evidenced by increased working memory performance (alternations) and locomotor activity, without negatively impacting other search strategies or cognitive flexibility. Chronic treatment with AMPH or NIC boosts cognitive performance in adult zebrafish. Cognitive sensitization occurred with both drugs, resulting in enhanced working memory; however, repeat AMPH exposure, following a withdrawal period, resulted in inhibited cognitive flexibility, an effect not evident with repeat NIC exposure. Cognitive and behavioral sensitization paradigms in zebrafish could serve as a useful tool for assessing cognitive states which result in cognitive enhancing or impairing effects of drugs.
Background: Zebrafish have been widely used to study anxiety-related phenotypes using the novel tank test (NTT). Although the NTT is well-characterized and commonly used by researchers, there is still a lack of information regarding how different experimental variables such as water quality can influence NTT performance. Zebrafish use different chemical cues and olfactory stimuli to communicate in water, so we predicted that water change frequency would affect cortisol, locomotion and anxiety-related parameters in the NTT. New methods: After extensive literature research, we found that only about 18% of papers using NTT report partial or complete water changes between subjects. Here, we tested multiple zebrafish in the NTT using the same water up to 9 consecutive times (with no water change) and analyzed cortisol levels, as a stressrelated marker. Results: We found that when using the same water for more than 4 trials, data variability is increased and a higher number of extreme values is observed for the time spent in the top zone and immobility. Moreover, after 4 trials with no water change, increased cortisol levels are observed, indicating that animals show increased stressrelated responses with the lack of water changes. Conclusions: This study shows that lack of water change can significantly influence zebrafish stress-responses in the NTT. Altogether, behavioral experiments should avoid using the same water when testing multiple fish in the task, especially when looking at anxiety in the NTT.
Taurine (TAU) is a β-amino sulfonic acid with pleiotropic roles in the brain, including the neuromodulatory activity via GABAergic and glycinergic agonism. This molecule is found at high concentrations in energy drinks and is often mixed with alcohol in beverages. Although TAU has a neuroprotective role in the brain, the putative risks of mixing TAU and EtOH are not fully understood. Here, we investigated whether TAU modulates locomotor and anxiety-like behavior in adult zebrafish by using the novel tank and light-dark tests following acute EtOH exposure at anxiogenic and anxiolytic concentrations. Zebrafish were individually exposed to water (control), TAU (42, 150, and 400 mg/L), and EtOH (0.25% (v/v) and 1% (v/v)) both independently and cotreated for 1 h. EtOH 0.25% and TAU produced U-shape anxiolytic-like behavior in the light-dark test, TAU 42 and 400 positively modulated EtOH effects, and TAU 150 exerted a protective effect. All TAU concentrations counteracted EtOH 1%-induced locomotion impairment, as well as the anxiogenic-like behavior. Finally, all TAU concentrations when given independently or cotreated with EtOH 0.25% and 1% decreased the risk assessment of the lit compartment. Principal component analyses revealed that exploration and anxiety-like responses were the main behaviors that contribute to the effects of TAU and EtOH. Overall, we demonstrate that TAU differently modulates EtOH-induced anxiolytic- and anxiogenic-like behaviors depending on the concentration, suggesting a complex mechanism underlying TAU and EtOH interactions.
Background: Zebrafish are used in anxiety research as the species' naturalistic diving response to a new envi-ronment is a reliable and validated marker for anxiety-like behavior. One of the benefits of using zebrafish is the potential for high throughput drug screens in fish at the larval stage. However, at present, tests of anxiety in larvae and adults often measure different endpoints.New method: Here, for the first time, we have adapted the novel tank diving response test for examining diving behavior in zebrafish larvae to assess anxiety-like behaviors at very early-stages (7 days-post-fertilization [dpf]).Comparison with existing methods: Current methods to examine anxiety in larvae can show low reliability, and measure different endpoints as in adults, thus calling into question their translational relevance. Results: We found that 7dpf zebrafish spent more time at the bottom of a small novel tank. We validated this as anxiety-like behaviors with diazepam reducing, and caffeine increasing the time spent in the bottom of the novel environment.Conclusions: This new automated and high-throughput screening tool has the potential use for screening of anxiogenic and anxiolytic compounds, and for studies aiming to better understand anxiety-like behaviors.
Early-life stress can lead to two different behavioral responses: (1) increased susceptibility to psychiatric disorders or (2) resilience. Here, we created a chronic unpredictable early-life stress (CUELS) protocol to assess the effects of early experiences in adult zebrafish. Animals were exposed to mild stressors twice a day and the duration was varied between groups (0, 1, 3, 7 and 14 days of stress). The stressor consisted of light/dark cycle changes; social isolation; overcrowding; water changes; water cooling; mechanical stirring; water heating; and immersion in shallow water. Behavior was assessed at young stages (21 days post-fertilization – open field analysis) and adulthood (4-months-old - novel tank diving test, light/dark task, shoaling, free movement pattern Y-maze and Pavlovian fear conditioning). Cortisol levels were assessed to evaluate the impact of CUELS in the HPI axis. Zebrafish exposed to 7 days of CUELS showed a decreased anxiety-like phenotype in two behavioral tasks, presenting increased time spent in top and decreased time spent in the dark area. Animals exposed to 14 days of CUELS showed an opposite anxious phenotype compared to 3 and 7 days of CUELS. No significant changes were observed in memory and cognition, social behavior and cortisol levels. In general, 7 days of CUELS protocol decreased anxiety in young and adult zebrafish, and could be used to understand the mechanisms underlying early-life experiences-derived alterations in neural circuits of anxiety. •An early-life stress protocol was developed and successfully affects zebrafish behavior without decreasing survival rate.•Chronic unpredictable early-life stress (CUELS) affects adult zebrafish anxiety-like phenotypes.•7 days of CUELS decreases anxiety in two different behavioral tasks.•CUELS neither affects social behavior nor memory and cognition.•Cortisol levels are not changed in animals exposed to CUELS protocol.
•Chronic unpredictable early-life stress (CUELS) is a reliable protocol for altering boldness/anxiety-like behavior in the novel tank test.•Boldness towards a new object is not affected by CUELS.•Increased cortisol induced by CAS are normal in adult animals exposed to CUELS.•7 and 14 days of CUELS show abnormal behavioral responses when exposed to CAS in the novel tank. Early-life stress (ELS) has been shown to result in a diverse array of long-lasting impacts; for example, increasing vulnerability to disease or building ‘resilience’ in adulthood. Previously, zebrafish (Danio rerio) have been used to understand the mechanisms by which ELS induces different behavioral phenotypes in adults, with alterations in both learning and anxiety observed in exposed individuals. Here, we subjected zebrafish larvae to chronic unpredictable early-life stress (CUELS) for 7 or 14 days, to investigate the impact on boldness towards a new environment and novel object, and stress-reactivity. We observed that 7 days of CUELS resulted in increased time spent in the top of a novel tank (indicating boldness) but did not alter approach to a novel object. Although CUELS did not affect stress-reactivity in terms of cortisol levels, decreased anxiety-like response to conspecific alarm substance (CAS) was observed in both ELS groups (7 and 14 days of CUELS). Therefore, for the first time, we observe a potential negative effect of CUELS by dampening the behavioral stress response following exposure to CAS. Overall, these data support the use of zebrafish as a translational model to study the broad range of ELS-induced permanent changes in behavior. It could also be used to investigate the mechanisms underlying both the positive and the negative effects of early-life adversity.
Acute stressors are recurrent in multiple species' lives and can facilitate or impair cognition. The use of zebrafish (Danio rerio) as a translational species to understand the mechanisms by which stress induces different behavioral phenotypes has been widely studied. Two acute stressors are recognized when using this species: (1) conspecific alarm substance (CAS); and (2) net chasing. Here, we tested if CAS or net chasing would affect working memory and cognitive flexibility by testing performance in the FMP Y-maze after exposure to stress. We observed that CAS altered zebrafish behavioral phenotypes by increasing repetitive behavior; meanwhile, animals showed different patterns of repetitive behavior when exposed to net chasing, depending on the chasing direction. Because D1 receptors were previously studied as a potential mechanism underlying stress responses in different species, here, we pretreated fish with a D1/D5 agonist (SKF-38393) to assess whether this system plays a role in repetitive behavior in the FMP Y-maze. The pretreatment with D1/D5 agonist significantly decreased repetitive behavior in CAS exposed animals, and cortisol levels for both stressed groups, suggesting that the dopaminergic system plays an important role in zebrafish stress-related responses. •Net chasing differently affects animals' repetitive behavior depending on the chasing direction.•CAS increases ARBs in the FMP Y-maze which is partially reversed by a D1/D5 agonist.•CAS and net chasing affect zebrafish cognitive flexibility.•D1/D5 agonist pretreatment attenuates the effects of stress increasing cortisol levels.
Abnormal repetitive behaviors (ARBs) are a prominent symptom of numerous human brain disorders and are commonly seen in rodent models as well. While rodent studies of ARBs continue to dominate the field, mounting evidence suggests that zebrafish (Danio rerio) also display ARB-like phenotypes and may therefore be a novel model organism for ARB research. In addition to clear practical research advantages as a model species, zebrafish share high genetic and physiological homology to humans and rodents, including multiple ARB-related genes and robust behaviors relevant to ARB. Here, we discuss a wide spectrum of stereotypic repetitive behaviors in zebrafish, data on their genetic and pharmacological modulation, and the overall translational relevance of fish ARBs to modeling human brain disorders. Overall, the zebrafish is rapidly emerging as a new promising model to study ARBs and their underlying mechanisms.
Ethanol (EtOH) is a central nervous system (CNS) depressant drug that modifies various behavioral domains (i.e., sociability, aggressiveness, and memory) by promoting disinhibition of punished operant behavior and neurochemical changes. Taurine (TAU) is a β-amino sulfonic acid with pleiotropic roles in the brain. Although exogenous TAU is found in energy drinks and often mixed with alcohol in beverages, the putative risks of mixing TAU and EtOH are poorly explored. Here, we investigated whether TAU modulates social and fear responses by assessing shoaling behavior, preference for conspecifics, and antipredatory behavior of adult zebrafish acutely exposed to EtOH. Zebrafish shoals (4 fish per shoal) were exposed to water (control), TAU (42, 150, and 400 mg/L), 0.25% (v/v) EtOH alone or in association with TAU for 1 h, and their behaviors were analyzed at different time intervals (0–5 min, 30–35 min, and 55–60 min). The effects of TAU and EtOH were further tested in a social preference test and during exposure to a predator. Both EtOH and TAU co-treated fish showed a higher shoal dispersion, while TAU 400/EtOH group shoal area had a similar profile when compared to control. However, in the social preference test, TAU 400/EtOH impaired the seeking for conspecifics. Regarding fear-like behaviors, TAU-cotreated fish showed a prominent reduction in risk assessments when compared to EtOH alone. Overall, we demonstrate that TAU modulates EtOH-induced changes in different behavioral domains, suggesting a complex relationship between social and fear-like responses. •Taurine affects shoaling behavior in adult zebrafish.•Taurine and ethanol display a temporal effect on zebrafish shoal cohesion.•Ethanol associated with high taurine concentrations decreases social preference.•Taurine potentiates ethanol-induced reduction in risk assessments.
Once considered a uniquely human attribute, behavioral laterality has proven to be ubiquitous among non-human animals, and is associated with several neurophenotypes in rodents and fishes. Zebrafish (Danio rerio) is a versatile vertebrate model system widely used in translational neuropsychiatric research owing to their highly conserved genetic homology, well-characterized physiological responses, and extensive behavioral repertoire. Although spontaneous left- and right-biased responses, and associated behavioral domains (e.g., stress reactivity, aggression, and learning), have previously been observed in other teleost species, no information relating to whether spontaneous motor left-right-bias responses of zebrafish predicts other behavioral domains has been described. Thus, we aimed to investigate the existence and incidence of natural left-right bias in adult zebrafish, exploiting an unconditioned continuous free movement pattern (FMP) Y-maze task, and to explore the relationship of biasedness on performance within different behavioral domains. This included learning about threat cues in a Pavlovian fear conditioning test, and locomotion and anxiety-related behavior in the novel tank diving test. Although laterality did not change locomotion or anxiety-related behaviors, we found that biased animals displayed a different search strategy in the Y-maze, making them easily discernable from their unbiased counterparts, and increased learning associated to fear cues. In conclusion, we showed, for the first time, that zebrafish exhibit a natural manifestation of motor behavioral lateralization which can influence aversive learning responses.
Drug abuse and brain disorders related to drug comsumption are public health problems with harmful individual and social consequences. The identification of therapeutic targets and precise pharmacological treatments to these neuropsychiatric conditions associated with drug abuse are urgently needed. Understanding the link between neurobiological mechanisms and behavior is a key aspect of elucidating drug abuse-related targets. Due to various molecular, biochemical, pharmacological, and physiological features, the zebrafish (Danio rerio) has been considered a suitable vertebrate for modeling complex processes involved in drug abuse responses. In this review, we discuss how the zebrafish has been successfully used for modeling neurobehavioral phenotypes related to drug abuse and review the effects of opioids, cannabinoids, alcohol, nicotine, and psychedelic drugs on the central nervous system (CNS). Moreover, we summarize recent advances in zebrafish-based studies and outline potential advantages and limitations of the existing zebrafish models to explore the neurochemical bases of drug abuse and addiction. Finally, we discuss how the use of zebrafish models may present fruitful approaches to provide valuable clinically translatable data.
Multiple species display robust behavioral variance among individuals due to different genetic, genomic, epigenetic, neuroplasticity and environmental factors. Behavioral individuality has been extensively studied in various animal models, including rodents and other mammals. Fish, such as zebrafish (Danio rerio), have recently emerged as powerful aquatic model organisms with overt individual differences in behavioral, nociceptive and other CNS traits. Here, we evaluate individual behavioral differences in mammals and fish, emphasizing the importance of cross-species analyses of intraspecies variance in experimental models of normal and pathological CNS functions. (C) 2019 IBRO. Published by Elsevier Ltd. All rights reserved.
Due to their well-characterized neural development and high genetic homology to mammals, zebrafish ( Danio rerio ) have emerged as a powerful model organism in the field of biological psychiatry. Here, we discuss the molecular psychiatry of zebrafish, and its implications for translational neuroscience research and modeling CNS disorders. In particular, we outline recent genetic and technological developments allowing for in-vivo examinations, high-throughput screening and whole-brain analyses in larval and adult zebrafish. We also summarize the application of these molecular techniques to the understanding of neuropsychiatric disease, outlining the potential of zebrafish for modeling complex brain disorders, including attention-deficit/hyperactivity disorder (ADHD), aggression, post-traumatic stress and substance abuse. Critically evaluating the advantages and limitations of larval and adult fish tests, we suggest that zebrafish models become a rapidly emerging new field in modern biological psychiatry research.
To facilitate smoking genetics research we determined whether a screen of mutagenized zebrafish for nicotine preference could predict loci affecting smoking behaviour. From 30 screened F sibling groups, where each was derived from an individual ethyl-nitrosurea mutagenized F fish, two showed increased or decreased nicotine preference. Out of 25 inactivating mutations carried by the F fish, one in the gene segregated with increased nicotine preference in heterozygous individuals. Focussed SNP analysis of the human locus in cohorts from UK (n=863) and Finland (n=1715) identified two variants associated with cigarette consumption and likelihood of cessation. Characterisation of mutant larvae and adult fish revealed decreased sensitivity to the dopaminergic and serotonergic antagonist amisulpride, known to affect startle reflex that is correlated with addiction in humans, and increased mRNA expression in mutant larvae. No effect on neuronal pathfinding was detected. These findings reveal a role for SLIT3 in development of pathways affecting responses to nicotine in zebrafish and smoking in humans.
Parallel visual search mechanisms have been reported previously only in mammals and birds, and not animals lacking an expanded telencephalon such as bees. Here we report the first evidence for parallel visual search in fish using a choice task where the fish had to find a target amongst an increasing number of distractors. Following two-choice discrimination training, zebrafish were presented with the original stimulus within an increasing array of distractor stimuli. We found that zebrafish exhibit no significant change in accuracy and approach latency as the number of distractors increased, providing evidence of parallel processing. This evidence challenges theories of vertebrate neural architecture and the importance of an expanded telencephalon for the evolution of executive function.
Exposure to alcohol during early central nervous system development has been shown variously to affect aspects of physiological and behavioural development. In extreme cases, this can extend to craniofacial defects, severe developmental delay and mental retardation. At more moderate levels, subtle differences in brain morphology and behaviour have been observed. One clear effect of developmental alcohol exposure is an increase in the propensity to develop alcoholism and other addictions. The mechanisms by which this occurs, however, are not currently understood. In this study, we tested the hypothesis that adult zebrafish chronically exposed to moderate levels of ethanol during early brain ontogenesis would show an increase in conditioned place preference for alcohol and an increased propensity towards habit formation, a key component of drug addiction in humans. We found support for both of these hypotheses and found that the exposed fish had changes in mRNA expression patterns for dopamine receptor, nicotinic acetylcholine receptor and -opioid receptor encoding genes. Collectively, these data show an explicit link between the increased proclivity for addiction and addiction-related behaviour following exposure to ethanol during early brain development and alterations in the neural circuits underlying habit learning.
The potential of zebrafish as a comparative model in behavioural neuroscience is currently hampered only by the lack of reliable and validated behavioural assays available to researchers. In the present experiment, we describe the performance of zebrafish in a test of attentional set formation. The fish were initially trained on a two-choice colour discrimination. Upon reaching acquisition criterion, the reinforced alternative was switched to the previously unreinforced alternative. Again, upon reaching criterion, the cues were replaced with a novel pair of colours (intra-dimensional shift) and reversed again on reaching criteria. We found that zebrafish show a steady decrease in trials-to-criteria over the four phases of the experiment, suggesting that they are forming and maintaining an attentional set, as has previously been demonstrated with mammals. Reversal learning deficits have been implicated in a variety of human psychological disorders (e.g., disorders of impulse control) and as such, we propose that performance of zebrafish in this procedure may represent a useful comparative model to complement existing rodent models. (C) 2012 Elsevier B.V. All rights reserved.
Exposure to moderate levels of ethanol during brain development has a number of effects on social behavior but the molecular mechanisms that mediate this are not well understood. Gaining a better understanding of these factors may help to develop therapeutic interventions in the future. Zebrafish offer a potentially useful model in this regard. Here, we introduce a zebrafish model of moderate prenatal ethanol exposure. Embryos were exposed to 20 mM ethanol for seven days (48hpf-9dpf) and tested as adults for individual social behavior and shoaling. We also tested their basal anxiety with the novel tank diving test. We found that the ethanol-exposed fish displayed reductions in social approach and shoaling, and an increase in anxiety in the novel tank test. These behavioral differences corresponded to differences in hrt1aa, slc6a4 and oxtr expression. Namely, acute ethanol caused a spike in oxtr and ht1aa mRNA expression, which was followed by down-regulation at 7dpf, and an up-regulation in slc6a4 at 72hpf. This study confirms the utility of zebrafish as a model system for studying the molecular basis of developmental ethanol exposure. Furthermore, it proposes a putative developmental mechanism characterized by ethanol-induced OT inhibition leading to suppression of 5-HT and up-regulation of 5-HT1A, which leads, in turn, to possible homeostatic up-regulation of 5-HTT at 72hpf and subsequent imbalance of the 5-HT system. (C) 2014 Elsevier Inc. All rights reserved.
Early life stress (ELS) is defined as a short or chronic period of trauma, environmental or social deprivation, which can affect different neurochemical and behavioral patterns during adulthood. Zebrafish (Danio rerio) have been widely used as a model system to understand human neurodevelopmental disorders and display translationally relevant behavioral and stress-regulating systems. In this study, we aimed to investigate the effects of moderate ELS by exposing young animals (6-weeks postfertilization), for 3 consecutive days, to three stressors, and analyzing the impact of this on adult zebrafish behavior (16-week postfertilization). The ELS impact in adults was assessed through analysis of performance on tests of unconditioned memory (free movement pattern Y-maze test), exploratory and anxiety-related task (novel tank diving test), and social cohesion (shoaling test). Here, we show for the first time that moderate ELS increases the number of alternations in turn-direction compared to repetitions in the unconditioned Y-maze task, suggesting increased working memory, but has no effect on shoal cohesion, locomotor profile, or anxiety-like behavior. Overall, our data suggest that moderate ELS may be linked to adaptive flexibility which contributes to build "resilience" in adult zebrafish by improving working memory performance.
The ability to visualise neural circuits in zebrafish in vivo is one of the most useful aspects of this model organism in neuroscience. To maintain the transparency of embryos, however, drugs, such as 1-pheyl-2-thiourea (PTU) must be added, or researchers can use mutants that do not develop pigment (e.g., the casper). The behavioural characteristics of such strains, however, have not been documented. Here, we tested adult zebrafish from the casper line, as well as wild-type (Tubingen, TU) and wild-types treated as embryos with PTU on three commonly used behavioural endpoints in neuroscience: novel tank test (similar to open-field in rodents), conditioned place preference for nicotine, and social cohesion (using a new method of cluster analysis). We found no differences between the casper and the TU, but the adult TU treated with PTU as embryos showed a marked increase in anxiety during the novel tank test. These data suggest that where possible, labs interested in analysis of developmental processes involved in adult phenotypes should avoid the use of PTU in favour of transparent mutants, such as casper.
Zebrafish are fast becoming one of the most widely used animal models in systems biology and developmental genetics, but their potential as models for behavioural neuroscience is only just beginning to be realised. This progress is dependent upon the rate at which behavioural assays for adult zebrafish are designed, reported and validated. As models for drug abuse and addiction, this species has been shown thus far to show high face validity, in that they show robust place preference for drug-related cues, as well as evidence for withdrawal, relapse and compulsive drug seeking. This review will outline the case for using zebrafish as models to study endophenotypes relating to drug addiction.
Zebrafish are an established and widely utilized developmental genetic model system, but limitations in developed behavioral assays have meant that their potential as a model in behavioral neuroscience has yet to be fully realized. Here, we describe the development of a novel operant behavioral assay to examine a variety of aspects of stimulus control in zebrafish using a 3 choice serial reaction time task (3 CSRTT). Fish were briefly exposed to three spatially distinct, but perceptually identical stimuli, presented in a random order after a fixed-time inter-trial interval (ITI). Entries to the correct response aperture either during the stimulus presentation, or within a brief limited hold period following presentation, were reinforced with illumination of the magazine light and delivery of a small food reward. Following training, premature responding was probed with a long-ITI session three times; once at baseline, once following a saline injection and once following an injection of a low dose of amphetamine (AMPH; 0.025 mg/kg). We predicted that if premature responding was related to impulsivity (as in rodents) it would be reduced following the AMPH injection. Results confirmed that zebrafish could learn to perform a complex operant task similar to tasks developed for rodents which are used to probe sustained attention and impulsivity, but the results from the AMPH trials were inconclusive. This study provides the foundations for development and further validation of this species as a model for some aspects of human attentional and impulse control disorders, such as substance abuse disorder. (C) 2011 Elsevier B.V. All rights reserved.
In zebrafish developmentally exposed to ambient ethanol (20mM-50mM) 1-9 days post fertilization (dpf), the cortisol response to stress has been shown to be significantly attenuated in larvae, juveniles and 6 month old adults. These data are somewhat at variance with similar studies in mammals, which often show heightened stress responses. To test whether these cortisol data correlate with behavioural changes in treated animals, anxiety-like behaviour of zebrafish larvae (9dpf and 10dpf) and juveniles (23dpf) was tested in locomotor assays designed to this end. In open field tests treated animals were more exploratory, spending significantly less time at the periphery of the arena. Behavioural effects of developmental exposure to ethanol were sustained in 6-month-old adults, as judged by assessment of thigmotaxis, novel tank diving and scototaxis. Like larvae and juveniles, developmentally treated adults were generally more exploratory, and spent less time at the periphery of the arena in thigmotaxis tests, less time at the bottom of the tank in the novel tank diving tests, and less time in the dark area in scototaxis tests. The conclusion that ethanol- exposed animals showed less anxiety-like behaviour was validated by comparison with the effects of diazepam treatment, which in thigmotaxis and novel tank diving tests had similar effects to ethanol pretreatment. There is thus a possible link between the hypophysealpituitary- interrenal axis and the behavioural actions of developmental ethanol exposure. The mechanisms require further elucidation.
Deficits in impulse control (difficulties in inhibition of a pre-potent response) are fundamental to a number of psychiatric disorders, but the molecular and cellular basis is poorly understood. Zebrafish offer a very useful model for exploring these mechanisms, but there is currently a lack of validated procedures for measuring impulsivity in fish. In mammals, impulsivity can be measured by examining rates of anticipatory responding in the 5-choice serial reaction time task (5-CSRTT), a continuous performance task where the subject is reinforced upon accurate detection of a briefly presented light in one of five distinct spatial locations. This paper describes the development of a fully-integrated automated system for testing impulsivity in adult zebrafish. We outline the development of our image analysis software and its integration with National Instruments drivers and actuators to produce the system. We also describe an initial validation of the system through a one-generation screen of chemically mutagenized zebrafish, where the testing parameters were optimized.
Cellular and molecular processes that mediate individual variability in impulsivity, a key behavioral component of many neuropsychiatric disorders, are poorly understood. Zebrafish heterozygous for a nonsense mutation in ache (ache(sb55/+)) showed lower levels of impulsivity in a 5-choice serial reaction time task (5-CSRTT) than wild type and ache(+/+). Assessment of expression of cholinergic (nAChR), serotonergic (5-HT), and dopamine (DR) receptor mRNA in both adult and larval (9dpf) ache(sb55/+) revealed significant downregulation of chrna2, chrna5, and drd2 mRNA in ache(sb55/+) larvae, but no differences in adults. Acute exposure to cholinergic agonist/antagonists had no effect on impulsivity, supporting the hypothesis that behavioral effects observed in adults were due to lasting impact of developmental alterations in cholinergic and dopaminergic signaling. This shows the cross-species role of cholinergic signaling during brain development in impulsivity, and suggests zebrafish may be a useful model for the role of cholinergic pathways as a target for therapeutic advances in addiction medicine.
Deficits in impulse control are related to a number of psychiatric diagnoses, including attention deficit hyperactivity disorder, addiction, and pathological gambling. Despite increases in our knowledge about the underlying neurochemical and neuroanatomical correlates, understanding of the molecular and cellular mechanisms is less well established. Understanding these mechanisms is essential in order to move towards individualized treatment programs and increase efficacy of interventions. Zebrafish are a very useful vertebrate model for exploring molecular processes underlying disease owing to their small size and genetic tractability. Their utility in terms of behavioral neuroscience, however, hinges on the validation and publication of reliable assays with adequate translational relevance. Here, we report an initial pharmacological validation of a fully automated zebrafish version of the commonly used five-choice serial reaction time task using a variable interval pre-stimulus interval. We found that atomoxetine reduced anticipatory responses (0.6 mg/kg), whereas a high-dose (4 mg/kg) methylphenidate increased anticipatory responses and the number of trials completed in a session. On the basis of these results, we argue that similar neurochemical processes in fish as in mammals may control impulsivity, as operationally defined by anticipatory responses on a continuous performance task such as this, making zebrafish potentially a good model for exploring the molecular basis of impulse control disorders and for first-round drug screening.
Zebrafish are a widely utilised animal model in developmental genetics, and owing to recent advances in our understanding of zebrafish behaviour, their utility as a comparative model in behavioural neuroscience is beginning to be realised. One widely reported behavioural measure is the novel tank-diving assay, which has been often cited as a test of anxiety and stress reactivity. Despite its wide utilisation, and various validations against anxiolytic drugs, reporting of pre-test housing has been sparse in the literature. As zebrafish are a shoaling species, we predicted that housing environment would affect their stress reactivity and, as such, their response in the tank-diving procedure. In our first experiment, we tested various aspects of housing (large groups, large groups with no contact, paired, visual contact only, olfactory contact only) and found that the tank diving response was mediated by visual contact with conspecifics. We also tested the basal cortisol levels of group and individually housed fish, and found that individually housed individuals have lower basal cortisol levels. In our second experiment we found ethanol appeared to have an anxiolytic effect with individually housed fish but not those that were group housed. In our final experiment, we examined the effects of changing the fishes' water prior to tank diving as an additional acclimation procedure. We found that this had no effect on individually housed fish, but appeared to affect the typical tank diving responses of the group housed individuals. In conclusion, we demonstrate that housing represents an important factor in obtaining reliable data from this methodology, and should be considered by researchers interested in comparative models of anxiety in zebrafish in order to refine their approach and to increase the power in their experiments.
Zebrafish have great potential to contribute to our understanding of behavioral genetics and thus to contribute to our understanding of the etiology of psychiatric disease. However, progress is dependent upon the rate at which behavioural assays addressing complex behavioral phenotypes are designed, reported and validated. Here we critically review existing behavioral assays with particular focus on the use of adult zebrafish to explore executive process and phenotypes associated with human psychiatric disease. We outline the case for using zebrafish as models to study impulse control and attention, discussing the validity of applying extant rodent assays to zebrafish and evidence for the conservation of relevant neural circuits.
•ADHD is a neurodevelopmental disorder that affects an increasing number of people worldwide.•Zebrafish is a prominent model to assess the underlying mechanisms of ADHD and it comorbidities.•Advantages and disadvantages of using zebrafish to model ADHD were discussed.•Current zebrafish ADHD models and future directions are highlighted. Attention deficit hyperactivity disorder (ADHD) is a common, debilitating neurodevelopmental disorder associated with inattentiveness, pathological hyperactivity and impulsivity. Despite the mounting human and animal evidence, the neurological pathways underlying ADHD remain poorly understood. Novel translational model organisms, such as the zebrafish (Danio rerio), are becoming important tools to investigate genetic and pathophysiological mechanisms of various neuropsychiatric disorders. Here, we discuss ADHD etiology, existing animal models and their limitations, and emphasize the advantages of using zebrafish to model ADHD. Overall, the growing utility of zebrafish models may improve our understanding of ADHD and facilitate drug discovery to prevent or treat this disorder.
Significant similarities exist between the neural and behavioural features of environmentally and drug-induced stereotypy. For example, exposure to dopamine agonists, such as amphetamine, induces stereotypy and causes alterations in midbrain neurophysiology similar to those observed following chronic stress. An additional behavioural feature of these neural changes in the drug-induced phenotype is an enhanced rate of switching from response-outcome (R-O) to stimulus-response (S-R) learning. The aim of the current experiment was to examine R-O and S-R learning in horses displaying environmentally induced oral stereotypies. This was achieved by employing variations of the place/response paradigm. In Experiment 1, we found that crib-biting horses displayed ‘response’ learning after 20 learning trials, whereas non-crib-biting controls tended to display ‘place’ learning throughout the experiment. In Experiment 2, we used a modified version of the procedure, in which the subjects were introduced to the maze from different start points and forced always to turn the same way. We found that the crib-biters acquired the task at a faster rate suggesting again that this group was displaying ‘response’ learning. Finally, in Experiment 3, we carried out an arena test to ensure that crib-biters were capable of ‘place’ learning. These results are the first to show that horses displaying an oral stereotypy, a behavioural phenotype previously associated with stress-induced perturbations of the basal ganglia, preferentially use ‘response’ learning. The findings are discussed in relation to the search for an aetiological model of stereotypy.
Human heart rate monitors (HRMs) are frequently used in equine studies to measure heart rate (HR) and interbeat intervals (IBIs). However, to date, the most commonly used HRM (the Polar® system) in horses has not been validated against simultaneously recorded electrocardiogram (ECG) signals during a range of ambulatory conditions. Polar® S810i and ECG IBIs were simultaneously recorded from six horses under three conditions commonly included in behavioural observation: standing at rest, loose in the stable and at liberty in a field. Following recording, Polar® IBI data were corrected for error processing in cardiac data. Corrected and uncorrected Polar® data were then compared with simultaneously recorded ECG data using a variety of commonly measured time and frequency domain parameters (e.g. HR variability (HRV)). Polar® data collected while horses were stabled or in the field were significantly different from ECG data, even following correction of the data, and therefore, it may not be possible for the two systems to be used interchangeably. This study indicates the need for caution while using Polar® S810i for collecting HRV data, unless horses are stationary, and even when the IBI data are corrected for measurement error.