Synaptic Mechanisms of General Anesthetic Action

全身麻醉作用的突触机制

• 批准号: 7145303
• 负责人: HUGH C HEMMINGS
• 金额: $ 44.89万
• 依托单位: WEILL MEDICAL COLL OF CORNELL UNIV
• 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 2010-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7145303
• 关键词: anesthetics; bacterial proteins; central nervous system; dopamine; gamma aminobutyrate; general anesthesia; glutamates; immunologic assay /test; intermolecular interaction; ion channel blocker; isoflurane; laboratory rat; membrane potentials; neural transmission; neuroanatomy; neurochemistry; neurophysiology; neurotransmitter transport; norepinephrine; pharmacokinetics; radiotracer; recombinant proteins; sodium channel; synapses; tissue /cell culture; voltage /patch clamp

DESCRIPTION (provided by applicant): The long-term goal of this competing continuation proposal is to understand the mechanisms of action of general anesthetics on synaptic transmission. Understanding the mechanisms of both the therapeutic and undesired effects of existing general anesthetics will facilitate their safe clinical use while enabling the rational development of more specific agents with reduced side-effects. Our central hypothesis is that general anesthetics affect neurotransmitter release by agent- and transmitter-specific presynaptic mechanisms involving effects on presynaptic ion channels. The project will be accomplished through a combination of neurochemical, electrophysiological and biochemical techniques via the following proposed Specific Aims: 1) Determine the mechanisms by which volatile anesthetics affect glutamate and GABA release from isolated nerve terminals to test the hypothesis that the effects of volatile anesthetics on glutamate and GABA release result from actions on presynaptic ion channels. 2) Characterize the electrophysiological effects of volatile anesthetics on voltage-gated Na+ channels to test the hypothesis that volatile anesthetics have state-dependent effects on voltage-gated Na+ channels at clinical concentrations. 3) Elucidate brain region-, transmitter- and age-dependent effects of volatile anesthetics on transmitter release in the CNS to test the hypothesis that heterogeneity in transmitter release mechanisms between various nerve terminal types results in differential presynaptic sensitivities to general anesthetics. Experiments will employ rodent nerve terminals isolated from various CNS regions to study presynaptic anesthetic effects in a subcellular fraction free of intercellular interactions and amenable to pharmacological, electrophysiological and biochemical analysis. Methods will include analysis of volatile anesthetic effects on basal and evoked release of radiolabeled glutamate, GABA, norepinephrine, and dopamine; comparison of the effects of isoflurane and other Na+ channel blockers on native, recombinant and bacterial Na+ channel biophysical properties; and immunochemical analysis of ion channels expressed in isolated nerve terminal preparations. Despite widespread clinical use, our understanding of how general anesthetics work is incomplete. Better understanding of their mechanisms will allow safer use of current anesthetics and facilitate development of anesthetics with fewer dangerous cardiovascular and respiratory side-effects.

描述（由申请人提供）：这项竞争性延续提案的长期目标是了解全身麻醉药对突触传递的作用机制。了解现有全身麻醉药的治疗作用和不良作用的机制将有助于其安全的临床使用，同时能够合理开发更特异性的药物并减少副作用。我们的中心假设是全身麻醉药通过药物和递质特异性突触前机制影响神经递质释放，涉及对突触前离子通道的影响。该项目将通过结合神经化学、电生理学和生物化学技术来完成，并提出以下具体目标：1）确定挥发性麻醉剂影响离体神经末梢谷氨酸和 GABA 释放的机制，以检验挥发性麻醉剂对谷氨酸和 GABA 释放的影响是由于对突触前离子通道的作用所致的假设。 2) 表征挥发性麻醉剂对电压门控 Na+ 通道的电生理效应，以检验挥发性麻醉剂在临床浓度下对电压门控 Na+ 通道具有状态依赖性影响的假设。 3) 阐明挥发性麻醉药对中枢神经系统递质释放的脑区域、递质和年龄依赖性影响，以检验以下假设：不同神经末梢类型之间递质释放机制的异质性导致突触前对全身麻醉药的敏感性不同。实验将利用从不同中枢神经系统区域分离的啮齿动物神经末梢来研究亚细胞部分的突触前麻醉作用，该亚细胞部分没有细胞间相互作用，并且适合药理学、电生理学和生化分析。方法将包括分析挥发性麻醉剂对放射性标记谷氨酸、GABA、去甲肾上腺素和多巴胺的基础和诱发释放的影响；比较异氟烷和其他Na+通道阻滞剂对天然、重组和细菌Na+通道生物物理特性的影响；对分离的神经末梢制剂中表达的离子通道进行免疫化学分析。尽管临床使用广泛，但我们对全身麻醉药作用原理的理解并不完整。更好地了解其机制将有助于更安全地使用现有麻醉剂，并促进开发危险的心血管和呼吸系统副作用更少的麻醉剂。