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: 7634445
• 负责人: Jaideep Kapur
• 金额: $ 43.92万
• 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/7634445
• 关键词: Adenosine; Animals; Anticonvulsants; Cholinergic Agents; Cholinesterase Inhibitors; Cholinesterases; 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; new therapeutic target; novel; patch clamp; presynaptic; programs; research study; tabun; therapeutic target; therapy development; 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）：该提案建议开发基于机制的新型疗法，用于治疗有机磷酸盐（OP）神经剂诱导的癫痫发作。中枢和外周胆碱酯酶抑制作用，例如Sarin，Soman和VX的OP神经剂，并增强胆碱能的传播。在实验动物中，所有已知神经剂在暴露后几分钟内产生抽搐的癫痫发作和状态癫痫症。在伊朗 - 伊拉克战争中暴露于神经毒剂中毒的人类以及使用沙林和VX的东京地铁攻击中，也观察到癫痫发作。操作引起的癫痫发作的机制仍然不确定。我们实验室的初步研究已使用OP paraoxon作为替代剂来研究操作诱导的癫痫发作。我们证明，将水氧化物浸入海马中会导致长时间的癫痫发作。此外，我们证明，在海马切片中引起癫痫发作的二氧氧气的浓度可以通过刺激从突触前末端释放谷氨酸释放谷氨酸来增强兴奋性神经传递。这些发现导致中央假设的提出指导了这一建议：op神经剂的抽搐浓度增强了谷氨酸能神经传递。该提案旨在确认有关OP剂对兴奋性传播的影响的初步发现，并测试候选化合物，从而减少了从突触前终末释放的谷氨酸释放，作为对胆碱能诱导的癫痫发作的潜在治疗。在三个目标中提出了实验，每个组都有特定的治疗干预措施的里程碑。我们提出了代表“ Go-no Go”决策点的定量结果标准。 AIM 1中概述的实验试图确认和扩展观察到的观察结果，即使用贴片夹电生理学和FM染料技术，可以从海马中增强谷氨酸从海马中增强谷氨酸释放。 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，以及腺苷及其类似物，以便在对照静止条件下减少谷氨酸释放并遵循OP刺激，使用斑块夹技术和FM染料技术。两类的化合物甘酸盐和神经肽Y被保留，如果两种拟议的药物之一未能将谷氨酸释放量减少30％，则将进行测试。 AIM 3：测试两类化合物在控制锂/毛car钙和OP二氨基诱导的癫痫持续状态的抗惊厥作用。两类化合物，神经肽Y和Galanin均保留，如果两种拟议的药物中的任何一种未能控制50％的实验动物中的地西epaepam难治性癫痫发作，则将进行测试。通过研究运算引起的癫痫发作的机制，我们提议确定用于治疗操作诱导的癫痫发作的新型治疗靶标。其次，我们建议基于新的治疗靶标开发疗法。此外，我们开发了一种可以在平民中使用的操作诱发的癫痫发作模型