Project 2: Persisting Neurobehavioral Dysfunction Caused by Interacting Toxicant Exposures During Development: Mechanistic and Treatment Studies with Zebrafish and Rats

摘要 持续的神经行为毒性已被证明是由于早期发育暴露于许多 不同类型的有毒物质，包括多环芳烃（PAH）和重金属。而 个别化学品的发育神经行为毒性已得到充分研究，它们的相互作用 尽管人们经常接触有毒物质的混合物，但事实并非如此。项目1的重点是 了解发育中的PAH暴露如何影响重金属的神经毒性作用。我们将使用 影响驱动的机制研究，从持续的神经行为功能障碍引起的 发育毒物暴露，以确定造成神经行为的关键机制， 毒性两种典型的多环芳烃（苯并[a]芘和荧蒽）和两种重金属（铅和 镉）产生持续的自发活动、情感功能障碍和认知障碍的改变 将被确定。机理研究的范围从分子（DNA甲基化）到细胞内 （与线粒体功能障碍相关的氧化应激）到细胞间（多巴胺、血清素和乙酰胆碱 神经递质损伤和小胶质细胞介导的炎症过程中的变化，通过IL-1β，6，10和 相关细胞因子）。在生物体水平上，行为应激反应增强 将确定多环芳烃和重金属的神经行为毒性。斑马鱼将被用作前端 模型，以评估PAH和重金属神经毒性的详细剂量-效应相互作用， 表征，绘制相互作用的剂量效应函数。老鼠将被用来确定性格， 与人类更直接相关的持续性神经行为障碍机制，包括性别选择性 方面的影响.从这个改进的神经行为毒性机制的理解工作，这个项目将 研究复杂环境的混合物。项目2将确定潜在救援的有效性 在毒物暴露期间使用抗氧化剂、甲基供体和抗炎细胞因子进行治疗。 这些将在斑马鱼中开发并用大鼠模型进行验证。另一种重要的毒物相互作用 是连续曝光在一个探索性的目标，我们将确定如何早期暴露于一种神经毒物， 导致适应不良的发展，这将损害对后来暴露于另一种神经毒物的反应。这 有毒物质暴露的连续变化对于理解通过 辈子项目2将与其他项目合作，特别是关于表观遗传学（项目3），氧化 压力（项目3和4），行为障碍（项目1和4），复杂的环境混合物（项目 1、4和5）、神经递质分析（分析化学核心）、混合物统计评价（数据 管理和分析核心），并与更广泛的社区共享信息（社区参与 核心），以加强对有毒混合物的真实的世界神经毒性风险的理解，并开发治疗方法， 减少不良神经行为毒性。

Abstract Persisting neurobehavioral toxicity has been shown to result from early developmental exposure to many different types of toxicants, including polyaromatic hydrocarbons (PAHs) and heavy metals. While the developmental neurobehavioral toxicity of individual chemicals have been well-studied, their interactions have not, despite the fact that people are most often exposed to toxicant combinations. Project 1 focuses on understanding how developmental PAH exposure impacts neurotoxic effects of heavy metals. We will use an effects-driven mechanistic investigation, working from the persisting neurobehavioral dysfunction caused by developmental toxicant exposures back to determine the critical mechanisms that caused the neurobehavioral toxicity. Interactions of two prototypic PAHs (benzo[a]pyrene and fluoranthene) and two heavy metals (lead and cadmium) producing persisting alterations in locomotor activity, emotional dysfunction and cognitive impairment will be determined. The mechanistic investigations will range from molecular (DNA methylation) to intracellular (oxidative stress related to mitochondrial dysfunction) to intercellular (dopamine, serotonin and acetylcholine neurotransmitter impairments and microglial-mediated changes in inflammatory processes via IL-1β, 6, 10 and related cytokines). At an organismal level, the importance of behavioral stress response potentiating neurobehavioral toxicity to PAHs and heavy metals will be determined. Zebrafish will be used as a front-end model to assess detailed dose-effect interactions of PAH and heavy metal neurotoxicity with isobolographic characterization, charting interacting dose-effect functions. Rats will be used to determine the character and mechanisms of persisting neurobehavioral impairment more directly relevant to humans, including sex-selective effects. Working from this improved mechanistic understanding of the neurobehavioral toxicity, this project will advance to the study of complex environmental mixtures. Project 2 will determine the efficacy of potential rescue treatments using antioxidants, methyl donors and anti-inflammatory cytokines during the toxicant exposure. These will be developed in zebrafish and verified with the rat model. Another important type of toxicant interaction is sequential exposures. In an exploratory aim we will determine how early exposure to one neurotoxicant could cause maladaptive development that would impair response to later exposure to another neurotoxicant. This sequential change in toxicant exposure is important for understanding risks of changing exposures through a lifetime. Project 2 will collaborate with the other projects, particularly regarding epigenetics (Project 3), oxidative stress (Projects 3 and 4), behavioral impairments (Projects 1 and 4), complex environmental mixtures (Projects 1, 4, and 5), neurotransmitter analysis (Analytic Chemistry Core), mixture statistical evaluation (Data Management and Analysis Core), and sharing information with the broader community (Community Engagement Core) to enhance understanding of real world neurotoxic risks to toxicant mixtures and develop treatments to reduce adverse neurobehavioral toxicity.