Pope-Presynaptic modulation of anticholinesterase toxicity

Pope-抗胆碱酯酶毒性的突触前调节

• 批准号: 8230715
• 负责人: CAREY N POPE
• 金额: $ 32.22万
• 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 2014-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8230715
• 关键词: 2-arachidonylglycerol; AM 251; Acetylcholine; Acetylcholinesterase; Acute; Affect; Agonist; Binding; Brain; CNR1 gene; Chlorpyrifos; Cholinergic Receptors; Cholinesterase Inhibitors; Corpus striatum structure; Dopamine; Endocannabinoids; Enzymes; Equilibrium; Glutamates; Health; Hippocampus (Brain); In Vitro; Insecticides; Label; Lead; Measures; Mediating; Microdialysis; Mus; Muscarinic M1 Receptor; Muscarinic M3 Receptor; Muscarinics; Neurons; Neurotoxins; Neurotransmitters; O,O-diethyl O-3,5,6-trichloro-2-pyridyl phosphate; Paraoxon; Parathion; Parents; Pathway interactions; Process; Rattus; Receptor Activation; Role; Seizures; Signal Pathway; Signal Transduction; Slice; Specificity; TRPV1 gene; Testing; Time; Tissues; Toxic effect; Tremor; anandamide; base; cannabinoid receptor; capsazepine; cholinergic; cholinergic synapse; comparative; dosage; extracellular; gamma-Aminobutyric Acid; in vivo; inhibitor/antagonist; neurotransmission; neurotransmitter release; organophosphorus insecticide; postsynaptic; presynaptic; receptor; response; uptake

DESCRIPTION (provided by applicant): Organophosphorus insecticides (OPs) elicit toxicity by inhibiting acetylcholinesterase, leading to acetylcholine accumulation at cholinergic synapses, excessive stimulation of cholinergic receptors and signs of acute toxicity (e.g., tremors, excessive secretions, seizures). The OPs parathion and chlorpyrifos elicit similar degrees of acetylcholinesterase inhibition and brain acetylcholine accumulation in vivo, yet markedly different degrees of toxicity. Accumulation of acetylcholine leads to "recruitment" of non-cholinergic signaling important in the expression of OP toxicity. Endocannabinoids (eCBs, e.g., anandamide, 2-arachidonyl glycerol, 2-AG) modulate neurotransmission by activating presynaptic cannabinoid receptors and inhibiting neurotransmitter release. Synthesis and release of eCBs can be increased by anticholinesterases through postsynaptic neuron depolarization or in a receptor- mediated fashion by activation muscarinic M1/M3 receptors. Furthermore, some OPs may directly alter eCB signaling by binding to cannabinoid receptors and/or inhibiting eCB metabolizing enzymes. We hypothesize that eCBs modulate the expression of anticholinesterase toxicity via inhibition of the release of downstream neurotransmitters involved in expression of anticholinesterase toxicity, and that differential direct actions of chlorpyrifos and parathion on the eCB signaling pathway lead to selective toxicity. Studies in aim 1 will evaluate the hypothesis that eCB signaling modulates cholinergic toxicity using pharmacological approaches. Preliminary studies indicate that chlorpyrifos selectively increases extracellular 2-AG levels in hippocampus. Studies in aim 2 will compare time-dependent effects of parathion and chlorpyrifos on both tissue and basal and depolarization-evoked extracellular eCB levels, and evaluate possible cellular mechanisms for OP-selective changes. Increases in dopaminergic, GABAergic and glutamatergic signaling have all been implicated in anticholinesterase toxicity. Aim 3 will compare in vitro, ex vivo and in vivo changes in these non-cholinergic signaling pathways elicited by parathion and chlorpyrifos. Finally, studies in aim 4 will compare sensitivity of CB1+/+ and CB1-/- mice to acute and subacute toxicity from parathion and chlorpyrifos and evaluate possible changes in neurotransmitter release elicited by parathion and/or chlorpyrifos and mediated through the CB1 receptor. PUBLIC HEALTH RELEVANCE: Project Narrative Many neurotoxicants including organophosphorus anticholinesterases elicit toxicity by disrupting the dynamic balance between synthesis, release and inactivation of neurotransmitters. Endocannabinoid signaling is a widespread neuromodulatory process that regulates neurotransmission via inhibition of neurotransmitter release. This project will evaluate the role of endocannabinoid signaling in the expression of anticholinesterase toxicity and determine whether its differential modulation participates in selective toxicity.

描述(申请人提供)：有机磷杀虫剂(OP)通过抑制乙酰胆碱酯酶，导致乙酰胆碱在胆碱能突触聚集，过度刺激胆碱能受体和急性毒性迹象(例如，震颤、过度分泌、癫痫发作)而引起毒性。有机磷农药对硫磷和毒死蜱在体内的乙酰胆碱酯酶抑制程度和脑乙酰胆碱蓄积程度相似，但毒性程度明显不同。乙酰胆碱的积累导致非胆碱能信号的“重新聚集”，这些信号在OP毒性的表达中起重要作用。内源性大麻素通过激活突触前大麻素受体和抑制神经递质的释放来调节神经传递。抗胆碱酯酶可通过突触后神经元去极化或以受体介导的方式激活M_1/M_3受体，从而增加ECB的合成和释放。此外，一些OP可能通过与大麻素受体结合和/或抑制ECB代谢酶来直接改变ECB信号。我们假设ECB通过抑制参与抗胆碱酯酶毒性表达的下游神经递质的释放来调节抗胆碱酯酶毒性的表达，毒死蜱和对硫磷在ECB信号通路上的不同直接作用导致选择性毒性。目标1中的研究将使用药理学方法评估ECB信号调节胆碱能毒性的假设。初步研究表明，毒死蜱选择性地增加了海马区细胞外2-AG的水平。Aim 2的研究将比较对硫磷和毒死蜱对组织以及基础和去极化引起的细胞外ECB水平的时间依赖效应，并评估OP选择性变化的可能细胞机制。多巴胺能、GABA能和谷氨酸能信号的增加都与抗胆碱酯酶毒性有关。目的3将在体外、体外和体内比较对硫磷和毒死蜱诱导的这些非胆碱能信号通路的变化。最后，目标4中的研究将比较CB1+/+和CB1-/-小鼠对对硫磷和毒死蜱急性和亚急性毒性的敏感性，并评估对硫磷和/或毒死蜱诱导并通过CB1受体介导的神经递质释放的可能变化。公共卫生相关性：项目描述包括有机磷抗胆碱酯酶在内的许多神经毒物通过破坏神经递质的合成、释放和失活之间的动态平衡而引起毒性。内源性大麻素信号是一种广泛存在的神经调节过程，通过抑制神经递质的释放来调节神经传递。本项目将评估内源性大麻素信号在抗胆碱酯酶毒性表达中的作用，并确定其差异调制是否参与选择性毒性。