Organophosphorus Pesticide Toxicology

描述(申请人提供)：有机磷(OP)杀虫剂是与杀虫剂有关的人类中毒的主要原因。最近对毒死蜱和二氮磷使用的限制反映了对人类健康，特别是儿童健康的持续关注。OP毒性作用的两个主要靶点是急性毒性的乙酰胆碱酯酶(AChE)和OP诱导的迟发性神经病(OPIDN)的神经病变靶标酯酶(NTE)。这项研究的重点是非胆碱能效应，部分是基于与合作者在无效AChE基因敲除小鼠(AChE-/-)和杂合子NTE基因敲除小鼠(NTE)上的发现。与野生型乳鼠(LD303 mg/kg)相比，AChE-/-小鼠对毒死蜱(CPO)(腹腔注射LD50为0.45 mg/kg)极为敏感，证实了不明非AChE靶标对急性致死的重要性。第一个具体目标是在哺乳动物中识别这种非AChE靶点。来自AChE-/-和野生型小鼠的小鼠脑蛋白将在体外和体外用[~3H-乙基]CPO进行放射性标记。[~3H]CPO水平极低的AChE/-和野生型小鼠的差异蛋白标记可以选择、纯化和鉴定OP急性中毒的候选替代靶点。第二个目的是以小鼠为模型，探讨NTE在OPIDN中的作用。NTE小鼠的NTE活性降低了40%，这使它们成为毒理学研究的理想对象。这些研究将集中在NTE水平与行为和神经病理变化的关系，NTE和野生型小鼠对辛基氟膦酸乙酯和其他OP延迟毒物的敏感性，OPIDN小鼠模型的验证，以及降低NTE导致多动和延迟毒性的机制。第三个目标是确定信号转导通路的破坏，更具体地说，是由溶血磷脂酶、二酰甘油脂肪酶和毒扁豆碱乙酰胆碱受体介导的毒性机制。最后一个目标是确定OP杀虫剂的两个二级靶点的机制和意义：OP通过与大麻素受体-1(CB1)激动剂结合的亲核位点上的OP磷酸化来改变内源性大麻的作用；犬尿氨酸甲酰胺酶(KFase)的结构和功能与大脑中的致畸作用和二氮磷牛的作用有关。在有机磷农药毒理学方面获得的知识也适用于作为化学战和恐怖主义毒剂的有机磷神经毒气。

DESCRIPTION (provided by applicant): Organophosphorus (OP) insecticides are the principal cause of pesticide-related human poisonings. Recent restrictions on the use of chlorpyrifos and diazinon reflect continuing concern for human health, particularly children. The two principal targets of OP toxicant action are acetylcholinesterase (AChE) for acute toxicity and neuropathy target esterase (NTE) for OP-induced delayed neuropathy (OPIDN). This research focuses on noncholinergic effects, based in part on findings with collaborators on nullizygous AChE-knockout mice (AChE -/-) and heterozygous NTE-knockout mice (NTE ). AChE -/- mice are extremely sensitive to chlorpyrifos oxen (CPO) (intraperitoneal LD50 0.45 mg/kg) compared with their wild-type littermates (LD30 3 mg/kg), establishing the importance of an unidentified non-AChE target for acute lethality. The first specific aim is to identify this non-AChE target in mammals. Mouse brain proteins from AChE -/- and wild-type mice will be radiolabeled in vitro and ex vivo with [3H-ethyl]CPO. Differential protein labeling in the AChE -/- and wild-type mice with very low levels of [3H]CPO will allow selection, purification and identification of the candidate alternate target of OP acute poisoning. The second aim is to establish the function of NTE in OPIDN using mice as the model. The NTE mice have a 40% reduction in NTE activity, making them ideal for toxicological investigations. The studies will focus on the association of NTE levels with behavioral and neuropathological changes, the sensitivity of NTE and wild-type mice to ethyl octylphosphonofluoridate and other OP delayed toxicants, validation of the mouse model for OPIDN and the mechanism by which lowered NTE induces hyperactivity and delayed toxicity. The third aim is to define the mechanisms of toxicity from disruption of signal transduction pathways, and more specifically those mediated by lysophospholipase, diacylglycerol lipase, and the muscarinic acetylcholine receptor. The last goal is to define the mechanisms and significance of two secondary targets of OP pesticides: altered endocannabinoid action by OP phosphorylation at a nucleophilic site coupled to the cannabinoid receptor-1 (CB1) agonist site; kynurenine formamidase (KFase) structure and function relative to teratogenesis and diazinon oxen action in the brain. Knowledge gained on OP pesticide toxicology is also applicable to OP nerve gases as chemical warfare and terrorism agents.