Julian Pittman

iPhone® applications as versatile video tracking tools to analyze behavior in zebrafish (Danio rerio)

Zebrafish (Danio rerio) are emerging as a promising model organism for experimental studies relevant to biological psychiatry. The objective of this study was to develop a novel video-based movement tracking and analysis system to quantify behavioral changes following psychoactive drug exposure in zebrafish. We assessed the effects of withdrawal from chronic ethanol exposure, and subsequent administration of fluoxetine (Prozac®), buspirone (Buspar®), and diazepam (Valium) using two behavioral paradigms; the Novel Tank Diving Test and the Light/Dark Choice Assay. A video tracking system was developed using two Apple® applications (Apps) to quantify these behaviors. Data from zebrafish exposed to the above treatments are presented in this paper not only to exemplify behavioral alterations associated with chronic exposure, but also more importantly, to validate the video tracking system. Following withdrawal from chronic ethanol exposure, zebrafish exhibited dose/time-dependent anxiogenic effects; including reduced exploration and freezing behavior in the Novel Tank Diving Test, and preference for the dark area for the Light/Dark Choice Assay. In contrast, the above drug treatments had significant anxiolytic effects. We have developed a simple and cost-effective method of measuring zebrafish behavioral responses. The iPhone® Apps outlined in this study offer numerous flexible methods of data acquisition; namely, ease of identification and tracking of multiple animals, tools for visualization of the tracks, and calculation of a range of analysis parameters. Furthermore, the limited amount of time required for interpretation of the video data makes this a powerful high-throughput tool with potential applications for pre-clinical drug development.

Startle response memory and hippocampal changes in adult zebrafish pharmacologically-induced to exhibit anxiety/depression-like behaviors.

Zebrafish (Danio rerio) are rapidly becoming a popular animal model for neurobehavioral and psychopharmacological research. While startle testing is a well-established assay to investigate anxiety-like behaviors in different species, screening of the startle response and its habituation in zebrafish is a new direction of translational biomedical research. This study focuses on a novel behavioral protocol to assess a tapping-induced startle response and its habituation in adult zebrafish that have been pharmacologically-induced to exhibit anxiety/depression-like behaviors. We demonstrated that zebrafish exhibit robust learning performance in a task adapted from the mammalian literature, a modified plus maze, and showed that ethanol and fluoxetine impair memory performance in this maze when administered after training at a dose that does not impair motor function, however, leads to significant upregulation of hippocampal serotoninergic neurons. These results suggest that the maze associative learning paradigm has face and construct validity and that zebrafish may become a translationally relevant study species for the analysis of the mechanisms of learning and memory changes associated with psychopharmacological treatment of anxiety/depression.

Understanding autism and other neurodevelopmental disorders through experimental translational neurobehavioral models

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.

Genetic and environmental modulation of neurodevelopmental disorders: translational insights from labs to beds

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 Panels 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.

Improving treatment of neurodevelopmental disorders: recommendations based on preclinical studies

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.

Developing Zebrafish Depression-Related Models

Animal models of disease are ultimately only as strong as the clinical phenotype(s) upon which they are based. Many obstacles impede our ability to design animal models of complex mental illnesses, such as depression. An animal model that attempts to re-create any disease strives to maximize construct, face, and predictive validities. Strategies to model depression in representative animals have largely focused on one or more symptoms of depression, which have left many knowledge gaps open. In approaching these knowledge gaps, there are three primary areas that we feel need to be focused on: development of translational animal models, identification of genetic determinants, and discovery of novel targets/biomarkers of depression. Here, we discuss how zebrafish may be utilized in the modeling and analysis of the mechanisms of depression. Furthermore, this chapter also provides a detailed description of the behavioral responses and makes recommendations for further development of these methods, and how they may be employed in forward genetic screening for mutations involved in depression-related phenotypes.

Zebrafish Neurotoxicity Models

The field of neurotoxicology is confronted with two significant demands: the testing of an ever increasing list of chemicals, and resource limitations/ethical concerns associated with testing using traditional mammalian species. National and international government agencies have well-defined a need to reduce, refine or replace mammalian species in toxicological testing with alternative testing methods and non-mammalian models. Toxicological assays using alternative animal models may relieve some of this pressure by allowing testing of more compounds while reducing expense and using fewer mammals. Recent advances in genetic technologies and the strong conservation between human and non-mammalian genomes allow for the dissection of the molecular pathways involved in neurotoxicological responses using genetically tractable organisms such as zebrafish (Danio rerio). A constantly increasing database on basic developmental biology, gene transfers, and the rich foundation of molecular genetic and genomic data make zebrafish a powerful modeling system for revealing mechanisms in neurotoxicology. In contrast to the highly advanced knowledge base on molecular developmental genetics in zebrafish, the databases regarding pathologic lesions in zebrafish lag far behind the information available on most other domestic mammalian and avian species, particularly rodents. Therefore, to fully utilize the potential of zebrafish as an animal model for understanding neurotoxicological influences on human development and disease we must greatly advance our knowledge on zebrafish diseases and pathology.