Mechanism and Treatment of nerve agent-induced seizures

神经毒剂诱发癫痫发作的机制和治疗

• 批准号: 7473892
• 负责人: Jaideep Kapur
• 金额: $ 42.64万
• 依托单位: UNIVERSITY OF VIRGINIA
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-09-27 至 2011-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7473892
• 关键词: Adenosine; Animals; Anticonvulsants; Cholinergic Agents; Cholinesterase Inhibitors; Cholinesterases; Class; Condition; Convulsants; Development; Diagnostic; Diazepam; Dose; Drug Formulations; Dyes; Electrophysiology (science); Galanin; Glutamates; Hippocampus (Brain); Human; Iran; Iraq; Laboratories; Lead; Lithium; Modeling; Motor Seizures; Organophosphates; Outcome; Paraoxon; Patch-Clamp Techniques; Peripheral; Pilocarpine; Poisoning; Presynaptic Terminals; Refractory; Research; Research Personnel; Rest; Sarin; Seizures; Slice; Soman; Somatostatin; Status Epilepticus; Subway; Techniques; Testing; Therapeutic Intervention; Tokyo; War; analog; base; cholinergic; cyclosarin; nerve agent; neuropeptide Y; neurotransmission; novel; novel therapeutics; patch clamp; presynaptic; programs; research study; tabun; therapeutic target; transmission process

DESCRIPTION (provided by applicant): This proposal proposes to develop novel, mechanism-based therapies for the treatment of organophosphate (OP) nerve agent-induced seizures. OP nerve agents, such as sarin, soman and VX act by central and peripheral cholinesterase inhibition and enhance cholinergic transmission. In experimental animals, all known nerve agents, produce convulsive seizures and status epilepticus within minutes of exposure. Seizures were also observed in humans exposed to nerve agent poisoning during the Iran-Iraq war, and in the Tokyo subway attacks where sarin and VX were used. The mechanism of OP-induced seizures remains uncertain. Preliminary studies in our laboratory have used the OP, paraoxon, as a surrogate agent to study OP-induced seizures. We demonstrate that low doses of paraoxon infused into the hippocampus cause prolonged seizures. Furthermore, we demonstrate that the concentrations of paraoxon that cause seizures in hippocampal slices can enhance excitatory neurotransmission by stimulating glutamate release from presynaptic terminals. These findings lead to the formulation of the central hypothesis guiding this proposal: convulsant concentrations of OP nerve agents enhance glutamatergic neurotransmission. This proposal seeks to confirm preliminary findings regarding the effect of OP agent on excitatory transmission and to test candidate compounds that diminish glutamate release from presynaptic terminals as potential therapy against seizures induced by cholinergic agents. Experiments are proposed within three aims, each group has specific milestones toward therapeutic interventions. We present quantitative outcomes criteria that represent "go-no go" decision points. Experiments outlined in Aim 1 seek to confirm and extend the observation that OP cholinesterase inhibitors enhance glutamate release from presynaptic terminals in the hippocampus, using patch clamp electrophysiology and FM dye technique. Experiments proposed in Aim 2 seek to test two classes of compounds, somatostatin and its analogs, and adenosine and its analogs, for their ability to diminish glutamate release during control resting conditions and following OP stimulation, using patch clamp technique and FM dye technique. Two classes of compounds, galanin and neuropeptide Y, are held in reserve and will be tested in case either one of the two proposed agents fail to reduce glutamate release by 30%. Aim 3: To test anticonvulsant action of two classes of compounds in controlling lithium/pilocarpine and OP paraoxon-induced status epilepticus. Two classes of compounds, neuropeptide Y and galanin are held in reserve and will be tested in case either one of the two proposed agents fail to control diazepam refractory seizures in 50% of experimental animals. By studying the mechanisms of OP-induced seizures, we are proposing to identify novel therapeutic targets for the treatment of OP-induced seizures. Second, we propose to develop therapies based on novel therapeutic targets. Furthermore, we develop a model of OP-induced seizures that can be used in civilian

描述（由申请人提供）：本提案旨在开发基于机制的新型疗法，用于治疗有机磷（OP）神经毒剂引起的癫痫发作。沙林、索曼、VX等OP神经毒剂通过抑制中枢和外周胆碱酯酶起作用，增强胆碱能传递。在实验动物中，所有已知的神经毒剂在暴露几分钟内就会引起惊厥发作和癫痫持续状态。在两伊战争期间暴露于神经毒剂中毒的人群中，以及在使用沙林和VX的东京地铁袭击中，也观察到癫痫发作。op诱发癫痫的机制尚不清楚。我们实验室的初步研究使用OP，对氧磷，作为替代物来研究OP引起的癫痫发作。我们证明，低剂量的对氧磷注入海马引起长时间的癫痫发作。此外，我们证明了在海马切片中引起癫痫发作的对氧磷浓度可以通过刺激突触前末端的谷氨酸释放来增强兴奋性神经传递。这些发现导致了指导这一建议的中心假设的形成：OP神经毒剂的惊厥浓度增强了谷氨酸能神经传递。本研究旨在证实OP剂对兴奋性传递的影响的初步发现，并测试减少突触前末端谷氨酸释放的候选化合物作为胆碱能药物诱导癫痫发作的潜在治疗方法。实验在三个目标内提出，每个组都有治疗干预的具体里程碑。我们提出了量化的结果标准，代表“go-no - go”决策点。Aim 1中概述的实验试图利用膜片钳电生理学和FM染色技术，证实并扩展OP胆碱酯酶抑制剂增强海马突触前末端谷氨酸释放的观察结果。Aim 2中提出的实验试图测试两类化合物，生长抑素及其类似物，腺苷及其类似物，它们在控制静息条件下和OP刺激后减少谷氨酸释放的能力，使用膜片钳技术和FM染料技术。两类化合物，丙氨酸和神经肽Y，被保留下来，如果两种提议的药物中的任何一种不能减少30%的谷氨酸释放，将进行测试。目的3：观察两类化合物在控制锂/匹洛卡平和OP对氧磷诱导的癫痫持续状态中的抗惊厥作用。两类化合物，神经肽Y和丙氨酸被保留下来，如果两种提议的药物中的任何一种不能控制50%的实验动物的地西泮难治性癫痫发作，将进行测试。通过研究op诱发癫痫发作的机制，我们提出了新的治疗op诱发癫痫发作的靶点。第二，我们建议基于新的治疗靶点开发治疗方法。此外，我们开发了一种可用于民用的op诱发癫痫发作模型