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可能受某些选择性影响的步骤，为区分毒性提供了基础。乙酰胆碱的释放及其受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。一些抗胆碱酯酶（包括对硫磷和毒死蜱的氧酮，即对氧磷和毒死蜱氧酮）直接与毒蕈碱M2受体（毒蕈碱自身受体的受体亚型）相互作用。使用灌注脑切片测量乙酰胆碱释放，注意到对氧磷和毒死蜱oxon的体外效应的定性差异以及体内对硫磷和毒死蜱暴露后毒蕈碱自身受体功能改变的时间依赖性差异。据推测，毒蕈碱自身受体功能是胆碱能毒性的重要调节剂，其活性的选择性调节或与年龄相关的差异可导致不同的毒性。在目标 1 中，将使用微透析技术在成年大鼠中比较对硫磷和毒死蜱对体内胆碱能毒性和乙酰胆碱释放的剂量相关影响。老年大鼠似乎对毒死蜱和对硫磷的急性作用更敏感。目标 2 的研究将评估乙酰胆碱释放/自身受体功能是否可能导致 OP 杀虫剂毒性的衰老相关差异。目标 3 将评估先前调节自身受体功能（通过输注自身受体激动剂、拮抗剂或 M2 受体反义）对成年大鼠对氧磷和毒死蜱毒性的影响。 M2 受体的 G 蛋白受体激酶 (GRK) 依赖性磷酸化启动受体脱敏、内化和下调。目标 4 中的研究将检验以下假设：一些 OP 毒物会差异性地改变 GRK 介导的 M2 受体磷酸化，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影响，确定自身受体功能在年龄相关敏感性中的相对作用，并评估 GRK 介导的 M2 调节途径的改变是否有助于选择性调节毒蕈碱一些 OP 毒物的自身受体功能。