CELLULAR MECHANISMS OF PRESYNAPTIC INHIBITION

突触前抑制的细胞机制

• 批准号: 2269666
• 负责人: SIMON T ALFORD
• 金额: $ 10.51万
• 依托单位: NORTHWESTERN UNIVERSITY AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-08-01 至 1998-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2269666
• 关键词: Agnatha; GABA receptor; alternatives to animals in research; calcium channel; calcium flux; electrophysiology; glutamate receptor; neural inhibition; neural transmission; neuromuscular function; neurophysiology; neurotransmitter transport; receptor expression; spinal cord; synapses

Modulation of transmitter release is integral to central nervous system (CNS) function. Understanding this phenomenon is, thus, important in understanding the vertebrate CNS, in which presynaptic terminals are mostly small and inaccessible. The goal of this project is to investigate amino acid receptor-mediated modulation of transmitter release from presynaptic terminals in the lamprey spinal cord. This preparation enables unequalled access to the terminal using imaging and electrophysiology. Properties of axonal voltage operated channels and presynaptic terminals will be investigated; particularly voltage operated Ca2+ channels. Activation of Ca2+ channels, while recording intracellular Ca2+ concentration by imaging Ca2+-sensitive fluorescent dye loaded into the axon through the recording electrode, will enable their localization. Voltage Step paradigms and pharmacological agents specific to.subtypes of Ca2+ channel will enable identification of channels at the presynaptic terminal. Concurrent to these experiments imaging of dye loaded paired postsynaptic somata will demonstrate spatial relationships between Ca2+ channels in the terminal and the site of synaptic contacts. Paired cell recordings of this form will be used to investigate the effects of amino acid application upon synaptic transmission. Application of reagents active at gamma aminobutyric acid (GABA) receptors will allow a detailed analysis of location and subtypes of GABA receptors involved in modulation of synaptic transmission. Observation of the effects of GABA receptor activation on voltage-activated Ca2+ entry to the presynaptic terminal and interference of 2nd messenger function by drug application to the interior of the terminal will be used to study the cellular mechanisms by which GABA receptor activation is transduced. Techniques of recording electrophysiologically and microfluorimetrically will also be pursued to investigate modes and sites of action of glutamate metabotropic receptors (mGluRs) in the pre- and post-synaptic elements of the lamprey spinal cord. Common mechanisms between mGluR and GABA receptor activation will be sought in the control of transmitter release, as well as mechanisms specific to each class of receptor. The roles of presynaptic GABA receptors and mGluRs in modulating motor output will be investigated. The effect of the activation or blockade of these receptors on spinal motor output will be tested. Additionally Ca2+ imaging of the axons will be used to investigate phase- and time-dependent changes in Ca2+ entry at different locations in the spinal cord. Thus it will be possible to relate cellular effects of presynaptic receptor activation to the control of the spinal motor system.

递质释放的调节是中枢神经系统不可或缺的一部分 （中枢神经系统）功能。因此，了解这一现象非常重要 了解脊椎动物的中枢神经系统，其中突触前末梢是 大多很小而且难以到达。该项目的目标是调查 氨基酸受体介导的递质释放调节 七鳃鳗脊髓的突触前末梢。这种准备使 使用成像和电生理学对终端进行无与伦比的访问。 轴突电压操作通道和突触前终端的特性 将被调查；特别是电压操作的 Ca2+ 通道。 激活 Ca2+ 通道，同时记录细胞内 Ca2+ 通过成像 Ca2+ 敏感荧光染料加载到 轴突通过记录电极，将使其定位。 电压阶跃范式和特定于亚型的药理制剂 Ca2+ 通道将能够识别突触前的通道 终端。与这些实验同时进行的染料加载配对成像 突触后体体将展示 Ca2+ 之间的空间关系 终端和突触接触部位的通道。 这种形式的配对细胞记录将用于研究 氨基酸应用对突触传递的影响。应用 对γ氨基丁酸（GABA）受体具有活性的试剂将允许 详细分析参与的 GABA 受体的位置和亚型 突触传递的调节。 GABA效果观察 电压激活的 Ca2+ 进入突触前受体激活 药物应用对第二信使功能的终止和干扰 终端的内部将用于研究细胞机制 GABA 受体激活通过它进行转导。录音技巧 还将采用电生理学和微荧光测定法 研究谷氨酸代谢受体的作用模式和位点 (mGluRs) 存在于七鳃鳗脊髓的突触前和突触后元件中 绳索。 mGluR 和 GABA 受体激活之间的共同机制是 寻求控制发射机释放以及机制 特定于每一类受体。 突触前 GABA 受体和 mGluR 在调节运动中的作用 输出将被调查。激活或封锁的效果 这些受体对脊髓运动输出的影响将得到测试。另外Ca2+ 轴突成像将用于研究相位和时间依赖性 脊髓不同位置 Ca2+ 进入的变化。因此它 将有可能将突触前受体的细胞效应联系起来 激活脊髓运动系统的控制。