High-throughput behavior-based dopaminergic drug discovery in the zebrafish

从历史上看，小分子一直是解剖神经系统功能不可或缺的工具。然而，发现新的精神药物化合物并确定它们影响行为的机制一直是困难的。在这里，我打算发现影响斑马鱼中多巴胺介导行为的新的神经活性化合物。这些研究旨在加快神经活性药物发现的步伐，并为了解脊椎动物的行为提供小分子工具。 抑郁症、焦虑症和精神分裂症等精神障碍是一种普遍且具有破坏性的疾病。尽管需要改进精神药物，但精神疾病和其他神经系统疾病的药物发现成功率低于其他治疗领域。神经系统的无与伦比的复杂性无疑增加了寻找具有可接受的毒性和副作用的新型和有效的神经活性药物的挑战。为了满足对新的神经活性药物的巨大需求，开发新的神经活性药物发现方法将是至关重要的。 由于神经系统的复杂性可能会在短期内排除对疾病病理学的完全机械性理解，因此在缺乏机械性理解的情况下有效的药物发现方法将具有特殊的价值。识别新的神经活性化学物质是开发精神药物的重要第一步。但是，由于缺乏对导致精神疾病的生化机制的详细了解，如何才能发现新的神经活性药物？ 遗传学和药理学是了解神经系统中分子信号通路的两种主要方法。然而，传统的药物遗传学方法严重偏向系统生物学的基因组方面。研究单一药物效果的全基因组应用正变得越来越普遍。相比之下，关于化学物质如何影响特定基因类型和表型的大规模分析进展缓慢得多。一个原因是，基于表型的化学筛选在大多数模式生物中并不实用或成本效益高。考虑到通过低通量和非系统方法发现的小分子的影响，基于系统行为的化学筛查可能有很大的帮助。 斑马鱼中基于表型的化学筛选是鉴定新的生物活性化合物的非传统方法。现代化学图书馆中很可能已经存在具有有价值的神经活性的未知化合物。然而，体外分析过于简单，哺乳动物的表型分析过于低通量，无法有效地识别这些有价值的分子。与较大的脊椎动物不同，斑马鱼足够小，可以很容易地与来自化学库的化学物质一起排列在96孔板的各个孔中。因此，斑马鱼中基于行为的化学筛选提供了系统地评估化学物质如何影响完整的脊椎动物神经系统的机会。 多巴胺(DA)修饰化合物是重要的治疗药物和有用的研究工具。然而，到目前为止，只发现了几类具有生物活性的几十年前的多巴胺修饰药物。这项建议的一个主要目标是利用斑马鱼中DA介导的行为作为生物测试来识别新的神经活性药物和靶点。DA信号的行为模型已经在小鼠和其他模式生物中得到了很好的表征，并被证明对识别已知的抗精神病药物具有很高的预测有效性。因此，改变斑马鱼中DA信号的新化合物也可能对治疗人类精神分裂症、躁狂和其他精神疾病的症状具有治疗活性。 在拟议的指导性研究期间，我的目标是在精神活性药物发现和开发的所有方面获得经验。这些技能将使我能够将我的初步发现发展为化学生物学和精神科药物发现的前沿领域的有效和可持续的研究计划。鉴于行为表型和神经活性药物在我们对精神疾病的理解和治疗中所发挥的历史作用，我预计在斑马鱼中进行系统的基于行为的化学筛选可能会加快神经活性药物的发现步伐，并提高我们对大脑和行为的理解。最终，我希望这项工作将导致治疗精神疾病和其他神经疾病的新疗法。

Historically, small molecules have been indispensable tools for dissecting nervous system function. However, it has been difficult to discover novel psychotropic compounds and determine the mechanisms by which they affect behavior. Here, I propose to discover new neuroactive compounds that affect dopamine-mediated behaviors in the zebrafish. These studies aim to accelerate the pace of neuroactive drug discovery and provide small-molecule tools for understanding vertebrate behavior. Psychiatric disorders such as depression, anxiety and schizophrenia are widespread and devastating illnesses. Despite the need for improved psychiatric medicines, drug discovery success rates for psychiatric illnesses and other disorders of the nervous system are lower than for other therapeutic areas. The unparalleled complexity of the nervous system undoubtedly contributes to the challenge of identifying novel and effective neuroactive drugs with acceptable toxicity and side effect profiles. To meet the vast unmet need for novel neuroactive drugs, it will be essential to develop new approaches to neuroactive drug discovery. Because the complexity of nervous system is likely to preclude complete mechanistic understanding of disease pathology in the near term, drug discovery approaches that can be effective in the absence of mechanistic understanding will be of particular value. Identifying novel neuroactive chemicals is an important first step toward developing psychiatric medicines. But, lacking a detailed understanding of the biochemical mechanisms that cause psychiatric disease, how can novel neuroactive drugs be discovered? Genetics and pharmacology are the two dominant approaches for understanding molecular signaling pathways in the nervous system. However, traditional pharmacogenetic approaches are heavily biased towards the genome side of systems biology. Genome-wide applications for investigating the effects of single drugs are becoming more common. By contrast, large-scale analyses of how chemicals affect specific genotypes and phenotypes have been much slower to develop. One reason is that phenotype based chemical screens have not been practical or cost-effective using most model organisms. Given the impact of small molecules that were discovered via low throughput and non-systematic approaches, it is likely that systematic behavior-based chemical screening has much to offer. Phenotype based chemical screens in the zebrafish are a non-conventional approach for identifying novel bioactive compounds. It is likely that uncharacterized compounds with valuable neuroactive activity already exist in the wells of modern chemical libraries. However, in vitro assays are too simplistic, and phenotypic assays in mammals too low throughput, to efficiently identify these valuable molecules. Unlike larger vertebrates, zebrafish are small enough to be easily arrayed in the individual wells of a 96-well plate along with chemicals from a chemical library. As a result, behavior-based chemical screens in the zebrafish provide the opportunity to systematically assess how chemicals affect the intact vertebrate nervous system. Dopamine (DA) modifying compounds are important therapeutic drugs and useful research tools. However, only a few bioactive classes of decades-old dopamine-modifying drugs have been identified to date. A main goal of this proposal is to utilize DA-mediated behaviors in the zebrafish as bioassays to identify novel neuroactive drugs and targets. Well-characterized behavioral models of DA signaling have been well- characterized in mice and other model organisms and have been proven to have high predictive validity for identifying known antipsychotic drugs. Thus, novel compounds that modify DA signaling in the zebrafish may also have therapeutic activity for treating the symptoms of schizophrenia, mania and other psychiatric diseases in humans. During the proposed period of mentored research, I aim to gain experience in all aspects of psychoactive drug discovery and development. These skills will enable me to develop my initial findings into an effective and sustainable research program on the leading edge of chemical biology and psychiatric drug discovery. Given the historical roles that behavioral phenotypes and neuroactive drugs have played in our understanding and treatment of mental illness, I expect systematic behavior-based chemical screening in the zebrafish may accelerate the pace neuroactive drug discovery and improve our understanding of the brain and behavior. Eventually, I hope that this work will lead to novel therapeutic approaches for treating mental illness and other neurological disorders.