Targeting M1/M3 Muscarinic Receptors to Treat Gestational Pesticide Poisoning

摘要 妊娠期有机磷农药中毒对孕妇和孕妇都是一种危及生命的疾病。 母亲和胎儿治疗严重依赖于使用高剂量的阿托品来阻断毒蕈碱 由于OP诱导的乙酰胆碱酯酶阻滞，乙酰胆碱（ACh）过度激活受体 （乙酰胆碱酯酶）。然而，尽管有治疗干预，自发流产、婴儿和/或产妇死亡， 产后神经系统并发症（包括癫痫发作和认知缺陷）可能随之而来。虽然很少 考虑到阿托品对所有毒蕈碱受体（mAChR）亚型的非选择性抑制， 是这些不良结果的重要决定因素。具体地说，抑制突触前mAChR（主要是 M2），它们是限制胆碱能神经元释放ACh的负反馈回路的一部分， 加剧OP诱导的胆碱能危象苯海索（THP）的药理作用 在怀孕期间安全使用，并被批准用于治疗肌张力障碍和帕金森病， 使其成为治疗妊娠期OP中毒的有吸引力的候选药物。与阿托品相比，THP选择性更强， 抑制M1和M3而不是M2 mAChR。此外，THP抑制尚未鉴定的神经元亚型， 烟碱型ACh受体（nAChRs）。胎盘中M1/M3 mAChRs和神经元nAChRs的过度激活 子宫肌层以及心肺和神经系统中的肿瘤可导致不良的健康结果 妊娠期间急性OP中毒。因此，本项目将测试假设，部分是由 除了M1/M3 mAChR外，还可能通过阻断nAChR来保留M2 mAChR， 治疗妊娠期OP中毒比阿托品更有效。重点将放在 毒死蜱（CPF），一种广泛使用的OP杀虫剂，目前被美国国土安全部列入 化学品威胁风险评估列出了可能用于毒害大量人口的化学品， 恐怖袭击一个多学科的方法，一个实验相关的动物模型（豚鼠），和一个 安慰剂对照、随机、盲法设计，最大限度地减少实验偏倚，最大限度地提高科学严谨性 将用于实现三个目标。目标1和2将确定THP的有效性，以拯救生命，减少 急性毒性的迹象，并防止母亲和胎儿神经系统并发症的发展 怀孕期间暴露于高剂量的CPF目标3将阐明有助于实现这一目标的机制。 CPF的毒性和THP的解毒效果。该项目的成功完成将为 为开发更有效的解毒剂治疗妊娠期急性CPF中毒奠定了基础。 确定可对人口健康结果产生积极影响的治疗干预措施 急性中毒的OP农药提供支持的倡议，世界卫生组织，以解决 急性有机磷农药中毒问题，特别是在发展中国家。此外，它还实现了一个未实现的 有效治疗这些杀虫剂蓄意袭击受害者的医疗需求。

ABSTRACT Poisoning with organophosphorus (OP) pesticides during gestation is a life-threatening condition for both mothers and fetuses. Treatment relies heavily on the use of high doses of atropine to block muscarinic receptor overactivation by acetylcholine (ACh) build up due to OP-induced block of acetylcholinesterase (AChE). However, despite therapeutic intervention spontaneous miscarriages, infant and/or maternal deaths, and postnatal neurological complications (including seizures and cognitive deficits) can ensue. Although rarely taken into account, the non-selective inhibition of all muscarinic receptor (mAChR) subtypes by atropine may be an important determinant of these poor outcomes. Specifically, inhibition of presynaptic mAChRs (mostly M2), which are part of a negative feedback loop that limits ACh release from cholinergic neurons, can exacerbate the OP-induced cholinergic crisis. The pharmacological profile of R,S-trihexyphenidyl (THP), a drug that has been safely used during pregnancy and is approved for treatment dystonia and Parkinson’s disease, makes it an attractive candidate to treat gestational OP poisoning. In contrast to atropine, THP more selectively inhibits M1 and M3 than M2 mAChRs. In addition, THP inhibits as-of-yet unidentified subtypes of neuronal nicotinic ACh receptors (nAChRs). Overactivation of M1/M3 mAChRs and neuronal nAChRs in the placenta and myometrium, and in the cardiorespiratory and nervous systems can contribute to poor health outcomes following acute OP intoxication during pregnancy. Thus, this project will test the hypothesis that, in part by sparing M2 mAChRs and potentially by blocking nAChRs in addition to M1/M3 mAChRs, THP will be more potent and efficacious than atropine to treat gestational OP poisoning. The focus will be on chlorpyrifos (CPF), a widely used OP pesticide currently included in the U.S. Department of Homeland Security Chemical Threat Risk Assessment list of chemicals that may be deployed to poison large numbers of people in terrorist attacks. A multidisciplinary approach, a translationally relevant animal model (the guinea pig), and a placebo-controlled, randomized, blind design that minimizes experimental bias and maximizes scientific rigor will be used to address three aims. Aims 1 and 2 will establish the effectiveness of THP to save lives, reduce signs of acute toxicity, and prevent the development of neurological complications in mothers and fetuses gestationally exposed to a high dose of CPF. Aim 3 will shed light on the mechanisms that contribute to the toxicity of CPF and the antidotal effectiveness of THP. Successful completion of this project will lay the groundwork for the development of more effective antidotes to treat acute CPF intoxication during pregnancy. Identification of therapeutic interventions that can have a positive impact on the health outcomes of populations acutely intoxicated with OP pesticides lends support to the initiative of the World Health Organization to tackle the issue of acute OP pesticide intoxication, particularly in the developing world. In addition, it fulfills an unmet medical need for the effective treatment of victims of a deliberate attack with these pesticides.