CELLULAR MECHANISMS OF PRESYNAPTIC INHIBITION

中枢神经系统对递质释放的调节是不可或缺的 (CNS)功能。因此，理解这一现象在 了解脊椎动物中枢神经系统，其中突触前终末是 大多很小，很难接近。这个项目的目标是调查 氨基酸受体介导的递质释放调控 七鳃鳗脊髓中的突触前终末。这一准备工作使 使用成像和电生理学无与伦比地访问终端。 轴突电压操作通道和突触前终末的特性 将被研究；特别是电压操作的钙离子通道。 激活钙通道，同时记录细胞内钙离子 通过成像钙离子敏感的荧光染料加载到 轴突通过记录电极，将使其能够定位。 电压阶跃范例和特定于以下亚型的药物 CA2+通道将使突触前通道的识别成为可能 终点站。与这些实验同时进行的染料负载配对成像 突触后胞体将显示钙离子之间的空间关系 终末和突触接触部位的通道。 这种形式的配对细胞记录将被用来调查 氨基酸应用对突触传递的影响。应用 活跃在伽马氨基丁酸(GABA)受体上的试剂将允许 详细分析了GABA受体的位置和亚型参与 突触传递的调制。氨基丁酸的药效观察 电压激活的钙离子进入突触前的受体激活 药物应用对第二信使功能的终末和干扰 航站楼内部将被用来研究细胞机制 通过它来传递GABA受体的激活。录音技巧 电生理学和显微荧光测量也将被用于 谷氨酸代谢性受体的作用模式和作用部位的研究 七鳃鳗脊髓突触前和突触后的(MGluRs) 电源线。MGluR和GABA受体激活之间的共同机制将是 寻求发射器释放的控制以及机制 对每一类受体都有特异性。 突触前GABA受体和mGluRs在调节运动中的作用 将对产出进行调查。激活或封锁的效果 这些对脊髓运动输出的受体将被测试。此外，钙离子 轴突的成像将被用来研究相位和时间相关 脊髓不同部位钙离子内流的变化。因此，它 可能与突触前受体的细胞效应有关 激活脊椎运动系统的控制。

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.