Nerve Terminal Regulation in the Cerebral Cortex

描述(申请人提供)：神经末梢的离子通道活动决定了突触前动作电位的形状和钙离子的进入，因此在突触传递的调节中起着关键作用。这在新皮质的突触前终末尤其重要，因为在正常情况下和疾病状态下，这一大脑区域在调节高级神经功能方面发挥着作用。我们最近开发了一种技术，可以从单个急性分离的大鼠新皮质神经末梢进行电生理记录。该实验室的长期目标是通过使用这项技术直接研究新皮质和突触前离子通道来回答有关突触传递的生理和病理生理调节的问题。细胞内[Ca~(2+)]i的升高是突触的一个关键信号，在那里它触发胞吐、可塑性和基因表达。关于细胞内钙离子变化的下游信号比细胞外[钙离子]o变化的影响知道的要多得多。然而，由于电活动，[Ca~(2+)]o可能会发生重大变化。这一提议的驱动假设是，突触间隙[Ca~(2+)]的减少是调节突触效能的重要信号。我们最近在新皮质神经末梢发现了一种新的、基于钙的信号通路，由电压敏感的非特异性阳离子(NSC)通道组成，该通道由[Ca~(2+)]o的减少激活。这一有趣的发现提出了一些问题：是什么机制检测到[Ca~(2+)]_o的变化并将其转化为膜电导的变化？神经末梢的钙离子感受器-神经干细胞通道信号通路是否受其他物质的调节？钙离子感受器-神经干细胞通道信号通路对突触传递的生理影响是什么？为了回答这些问题，我们计划结合电生理学、药理学和免疫化学技术来：1.鉴定钙离子感受器-神经干细胞通道信号通路的成分。2.确定钙离子感受器-神经干细胞通道信号通路的生理调节剂。3.确定钙离子感受器-神经干细胞通道信号通路在突触传递中的作用。本研究的目的是了解[Ca~(2+)]_o调节大脑皮层神经末梢突触中离子通道活性的机制，并确定这个Ca~(2+)感受器-NSC通道信号通路如何影响新皮质中的突触传递。

DESCRIPTION (provided by applicant): Ion channel activity at the nerve terminal determines presynaptic action potential shape and Ca2+ entry and thus plays a pivotal role in the regulation of synaptic transmission. This is particularly important in the presynaptic terminals of the neocortex, due to this brain region's role in mediating higher neurological function under normal conditions and during disease states. We have recently developed a technique that permits electrophysiological recording from single, acutely isolated rat neocortical nerve terminals. The long-term objective of the laboratory is to answer questions about the physiological and pathophysiological regulation of synaptic transmission by directly studying neocortical, presynaptic ion channels with this technique. An increase in intracellular [Ca2+] ([Ca2+]i) is a critical signal at the synapse where it triggers exocytosis, plasticity and gene expression. Much more is known about signaling downstream of changes in intracellular Ca2+ than about the impact of changes in extracellular [Ca2+] ([Ca2+]o). Yet [Ca2+]o is likely to undergo significant changes as a result of electrical activity. The driving hypothesis for this proposal is that a decrease in synaptic cleft [Ca2+] is an important signal which regulates synaptic efficacy. We have recently discovered a novel, Ca2+-based signaling pathway in neocortical nerve terminals, comprised of a voltage sensitive non-specific cation (NSC) channel activated by decreases in [Ca2+]o. This interesting finding poses a number of questions: what is the mechanism by which changes in [Ca2+]o are detected and transduced to alterations in membrane conductance? Is the Ca2+ sensor-NSC channel signaling pathway modulated by other agents at the nerve terminal? What is the physiological impact of Ca2+ sensor-NSC channel signaling pathway on synaptic transmission? To answer these questions we plan to use a combination of electrophysiological, pharmacological and immunochemical techniques to: 1. Identify the constituents of the Ca2+ sensor-NSC channel signaling pathway. 2. Determine physiological modulators of Ca2+ sensor-NSC channel signaling pathway. 3. Determine the role of the Ca2+ sensor-NSC channel signaling pathway in synaptic transmission. The goals of this proposal are to understand the mechanism by which [Ca2+]o modulates ion channel activity in the synapses of the cortical nerve terminals and to determine how this Ca2+ sensor-NSC channel signaling pathway impacts synaptic transmission in the neocortex.