CELLULAR MECHANISMS OF PRESYNAPTIC INHIBITION

突触前抑制的细胞机制

• 批准号: 2269664
• 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 1997-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2269664
• 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.

发射器释放的调节与中枢神经系统不可或缺 （CNS）功能。因此，了解这种现象在 了解脊椎动物中枢神经系统，其中突触前终端是 大部分小而无法访问。该项目的目的是调查 氨基酸受体介导的发射机释放的调制 七lamp虫的脊髓中突触前末端。此准备可以实现 使用成像和电生理学进入末端的无与伦比访问。 轴突电压操作的通道和突触前端子的性能 将被调查；特别是电压操作的Ca2+通道。 CA2+通道的激活，同时记录细胞内Ca2+ 通过成像Ca2+敏感荧光染料的浓度 轴突通过记录电极，将实现其定位。 电压步骤范例和药理剂特有的。 CA2+通道将在突触前识别通道 终端。这些染料负载成对的这些实验成像的同时存在 突触后索马塔将证明Ca2+之间的空间关系 终端和突触接触部位的通道。 该形式的配对细胞记录将用于研究 氨基酸对突触传播的影响。应用 在伽马氨基丁酸（GABA）受体上活跃的试剂将允许 对参与的GABA受体的位置和亚型的详细分析 突触传播的调节。观察GABA的影响 电压激活的Ca2+进入突触前的受体激活 通过药物施用第二信使功能的终端和干扰 末端的内部将用于研究细胞机制 通过转导GABA受体激活。录音技术 电生理学和微氟化图也将被追捕 研究谷氨酸代谢受体的模式和作用部位 （mglurs）在lamp脊柱的前后突触后元素中 绳索。 MGlur和GABA受体激活之间的常见机制将是 在控制发射机释放和机制中寻求的 特定于每类受体。 突触前GABA受体和mglurs在调节电动机中的作用 输出将进行研究。激活或阻塞的影响 将测试这些脊柱运动输出的受体。另外CA2+ 轴突的成像将用于研究相位和时间依赖性 脊髓不同位置的Ca2+进入的变化。因此 可以将突触前受体的细胞作用联系起来 激活脊柱运动系统的控制。