Presynaptic modulation of anticholinesterase toxicity

抗胆碱酯酶毒性的突触前调节

• 批准号: 7087850
• 负责人: CAREY N POPE
• 金额: $ 31.68万
• 依托单位: OKLAHOMA STATE UNIVERSITY STILLWATER
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-08-01 至 2008-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7087850
• 关键词: G protein coupled receptor kinase; acetylcholinesterase; affinity chromatography; age difference; cholinergic receptors; cholinesterase inhibitors; environmental toxicology; hippocampus; laboratory rat; microdialysis; muscarinic receptor; neurotransmitter transport; organophosphorus insecticide; parathion; pesticide biological effect; phosphorylation; protein structure function; receptor binding; synapses; tissue /cell culture; toxin metabolism

DESCRIPTION (provided by applicant): The mechanism of toxicity for organophosphorus (OP) anticholinesterases involves steps which may be selectively affected by some, providing a basis for differential toxicity. Acetylcholine release and its regulation by inhibitory muscarinic autoreceptors may be pivotally important in OP toxicant-selective toxicity. Some anticholinesterases (including the oxons of both parathion and chlorpyrifos, i.e., paraoxon and chlorpyrifos oxon) directly interact with muscarinic M2 receptors, the receptor subtype of muscarinic autoreceptors. Using superfused brain slices to measure acetylcholine release, both qualitative differences in the in vitro effects of paraoxon and chlorpyrifos oxon and time-dependent differences in the alteration of muscarinic autoreceptor function following in vivo parathion and chlorpyrifos exposures were noted. It is hypothesized that muscarinic autoreceptor function is an important modifier of cholinergic toxicity and that selective modulation or age-related differences in its activity can lead to differential toxicity. In aim 1, the dose-related effects of parathion and chlorpyrifos on cholinergic toxicity and acetylcholine release in vivo using microdialysis techniques will be compared in adult rats. Aged rats appear more sensitive to the acute effects of both chlorpyrifos and parathion. Studies in aim 2 will evaluate whether acetylcholine release/autoreceptor function may contribute to aging-related differences in OP insecticide toxicity. Aim 3 will evaluate the consequences of prior modulation of autoreceptor function (by infusion of autoreceptor agonist, antagonist or M2 receptor antisense) on paraoxon and chlorpyrifos oxon toxicity in adult rats. G-protein receptor kinase (GRK)-dependent phosphorylation of M2 receptors initiates receptor desensitization, internalization and down-regulation. Studies in Aim 4 will test the hypothesis that some OP toxicants differentially alter GRK-mediated phosphorylation of M2 receptors leading to selective changes in receptor regulation. These studies should clarify the selective effects of OP insecticides on acetylcholine release/autoreceptor function in vivo, determine the relative role of autoreceptor function in age-related sensitivity, and evaluate whether alteration of GRK-mediated M2 regulatory pathways contribute to the selective modulation of muscarinic autoreceptor function by some OP toxicants.

描述（由申请人提供）：有机磷（OP）抗胆碱酯酶的毒性机制涉及的步骤可能会被某些人选择性影响，从而为差异毒性提供了基础。乙酰胆碱释放及其对抑制性毒蕈碱自身受体的调节可能在OP毒物选择性毒性中至关重要。一些抗精酯酶（包括parathion和毒死rif的牛，即副氧氧棒和毒死rif氧牛）直接与毒蕈碱自身自动蛋白酶的受体亚型的毒蕈碱M2受体直接相互作用。使用超级灌注的脑切片来测量乙酰胆碱释放，在体内parathion和毒蕈碱自身受体功能变化的变化中，二氧谁体外效应的定性差异以及时间依赖性差异。假设毒蕈碱自身受体功能是胆碱能毒性的重要修饰符，其活性的选择性调节或与年龄相关的差异可能导致差异毒性。在AIM 1中，将在成年大鼠中比较Parathion和Chlorpyrifos对体内胆碱能毒性和乙酰胆碱释放的剂量相关作用。老年大鼠似乎对毒死rif和parathion的急性影响更为敏感。 AIM 2中的研究将评估乙酰胆碱释放/自身受体功能是否可能导致与衰老相关的OP杀虫剂毒性差异。 AIM 3将评估自感受器功能的事先调节（通过输注自感受器激动剂，拮抗剂或M2受体反义）对成年大鼠中的副氧气和毒死rif毒性的毒性。 M2受体的G蛋白受体激酶（GRK）依赖性磷酸化引发受体脱敏，内在化和下调。 AIM 4中的研究将检验以下假设：一些OP有毒物质差异改变了GRK介导的M2受体的磷酸化，从而导致受体调节的选择性变化。这些研究应阐明OP杀虫剂对体内乙酰胆碱释放/自身受体功能的选择性作用，确定自感受器功能在与年龄相关的敏感性中的相对作用，并评估GRK介导的M2调节途径是否有助于通过某些OP毒素的肌肉自身障碍毒素的选择性调节。