Pesticide-Mediated Generation of a Toxic Neurotransmitter Metabolite

项目总结 接触有机氯狄氏剂会使人容易患上帕金森氏症；然而， 暴露于疾病与多巴胺能细胞选择性丧失之间的联系机制尚不清楚。此外, 狄氏剂本身可能不足以治疗多巴胺(DA)神经元的丧失，而神经退行性变可能需要 额外的“命中”，例如来自遗传学的。几个动物模型已经证明，改变DA代谢 和/或贩卖会导致DA神经元的进行性丧失；因此，一种修改DA的基因变异 新陈代谢可能是另一种与杀虫剂接触具有毒性协同作用的“打击”。DA以外的细胞类型 神经元被认为与PD有关，如胶质细胞，通过胶质细胞激活释放的毒性因子 认识到是疾病进展的关键贡献者。多巴胺神经元和神经胶质细胞(如星形胶质细胞) 代谢多巴胺和其他神经递质，并产生有毒中间体，如ROS和醛 (3，4-二羟基苯乙醛，DOPAL)，通过单胺氧化酶。基于文献先例和 初步数据，我们建议将DA代谢和转运作为农药狄氏剂的一个机制靶点 这会产生活性和毒性中间体的积聚，如DOPAL和神经炎症。而当 多巴胺及其对苯二酚的作用作为神经毒性的一种机制已经被探索过，但对此知之甚少 DOPAL和醛代谢的作用。DOPAL生成是作为一种统一机制提出的 接触农药、神经炎症和儿茶酚胺能细胞丧失。这项工作的目的是阐明 神经退行性疾病环境风险因素的潜在机制，特别关注 农药狄氏剂与DA能和胶质细胞的相互作用及对多巴胺能神经元的损伤 活性中间体，如DOPAL。此外，还将探讨基因与环境的相互作用 狄氏剂本身可能不足以导致DA神经元的丧失。中心假设是杀虫剂 狄氏剂靶向DA代谢和/或转运神经元和神经胶质细胞，产生反应性醛代谢物 这会损伤DA神经元，促进神经胶质细胞的炎症激活。三个目标将是 完成：1)确定农药暴露对转基因小鼠黑质纹状体DA系统的影响 伴随着DA代谢的改变。2)确定胶质衍生的反应性DA中间体对 农药介导的神经元损伤。3)确定活性中间体的细胞和分子靶点。一个 体内和体外的创新和包罗万象的方法将与强大的小鼠遗传策略一起使用 缺乏或过度表达对DA代谢至关重要的酶。这些具体的目标将建立 基于之前的工作，以解决关于关键的细胞相互作用的关键机械问题 星形胶质细胞和神经元加剧了因接触杀虫剂而导致的功能障碍。

PROJECT SUMMARY Exposure to the organochlorine dieldrin predisposes individuals to Parkinson's Disease (PD); however, the mechanisms linking exposure to disease and selective loss of dopaminergic cells are unknown. In addition, dieldrin alone may be insufficient for loss of dopamine (DA) neurons, and neurodegeneration may require an additional “hit”, such as from genetics. Several animal models have demonstrated that altering DA metabolism and/or trafficking yields progressive loss of DA neurons; therefore, a genetic variation modifying DA metabolism may be an additional “hit” that has toxic synergy with pesticide exposure. Cell types other than DA neurons are thought to be involved in PD, such as glia, and toxic factors released via glial activation are realized as a critical contributors to disease progression. Both DA neurons and glial cells (e.g., astrocytes) metabolize DA and other neurotransmitters and generate toxic intermediates such as ROS and aldehydes (3,4-dihydroxyphenylacetaldehyde, DOPAL), via monoamine oxidase. Based on literature precedent and preliminary data, we propose DA metabolism and trafficking as a mechanistic target for the pesticide dieldrin that can produce a build-up of reactive and toxic intermediates such as DOPAL and neuroinflammation. While the role of DA and its quinone have been explored as a mechanism for neurotoxicity, very little is known about DOPAL and the role of aldehyde metabolism. DOPAL generation is proposed as a mechanism unifying pesticide exposure, neuroinflammation and loss of catecholaminergic cells. The goal of this work is to elucidate mechanisms underlying environmental risk factors for neurodegenerative disease, specifically focusing on the interaction of the pesticide dieldrin with DArgic and glia and resulting injury to dopaminergic neurons via reactive intermediates such as DOPAL. In addition, the gene-environment interaction will be explored as dieldrin alone may be insufficient to cause loss of DA neurons. The central hypothesis is that pesticides such as dieldrin target DA metabolism and/or trafficking in neurons and glia, yielding reactive aldehyde metabolites that damage DA neurons and promote neuroinflammatory activation of glial cells. Three Aims will be completed: 1) Determine the effects of pesticide exposure on the nigro-striatal DA system in transgenic mice with altered DA metabolism. 2) Determine the contribution of glial-derived reactive DA intermediates to pesticide-mediated neuronal injury. 3) Identify cellular and molecular targets of reactive intermediates. An innovative and encompassing approach in vivo and in vitro will be used with a robust genetic strategy of mice that are deficient or have overexpression of enzymes key to DA metabolism. These Specific Aims will build upon previous work to address key mechanistic questions regarding critical cellular interactions between astrocytes and neurons that potentiate dysfunction caused by exposure to pesticides.