DEPOLARIZATION-SECRETION COUPLING IN NERVE TERMINALS

描述 神经递质的释放是轴突棘波侵入神经的结果。 终点站。尽管有相当多的证据表明， 神经元胞体导致钙离子进入并随后分泌 神经递质和/或神经激素，如何离子的分子细节 电流控制神经末梢中神经活性物质的释放 仍未确定。这一提议利用了一种哺乳动物系统 这些问题可以直接解决。很多事情都已经知道了 关于大鼠神经垂体的电活动及其后遗症 加压素和催产素等多肽激素的释放一直很好。 特色化的。现在唯一可能制备的是分离的神经 这种神经内分泌结构的终末对去极化有反应 通过钙离子依赖的胞吐作用释放识别的多肽。 此外，神经垂体的释放是由特定的 电活动的模式。因此，这些神经末梢拥有所有 所需属性的详细分析过程 去极化-分泌耦合(神经肽是如何在 对神经末梢膜去极化的反应)。我们建议 研究，使用复杂的膜片钳、成像和生化 方法学，根据分泌的多肽来鉴定的生理学， 神经末梢与它们的差异释放 神经肽。特别是，我们建议详细地描述钙离子 通道，包括在单通道级别上验证 有争议的“Q”型药物的动力学和药理学，在这些 神经末梢。我们将对不同的神经垂体钙离子进行定位 不同类型的终端之间以及各个终端内的通道 与可能的释放地点有关。最后，我们将确定哪些类型 对后叶加压素和催产素的释放很重要。澄清： 这种相互作用背后的分子机制将代表一个主要的 对神经元通讯如何调控的理解取得了进展。

DESCRIPTION Neurotransmitter release occurs as a result of axonal spikes invading nerve terminals. Although there is considerable evidence that depolarization of neuronal somata leads to the entry of Ca+ and to the subsequent secretion of neurotransmitters and / or neurohormone, the molecular details of how ionic currents control the release of neuroactive substances from nerve terminals remain undetermined. This proposal takes advantage of a mammalian system in which these questions can be directly addressed. Much is already known about the electric activity of the rat neurohypophysis and the subsequent release of the peptide hormones, vasopressin and oxytocin,has been well characterized. It is now uniquely possible to prepare isolated nerve terminals from this neuroendocrine structure which respond to depolarization by releasing identified peptides via Ca2+ - dependent exocytosis. Furthermore, release from the neurohypophysis is regulated by specific patterns of electrical activity. Thus, these nerve terminals have all the properties necessary to analyze in detail the process of depolarization-secretion coupling (how neuropeptides are released in response to depolarization of the nerve terminal membrane). We propose to study, using sophisticated patch-clamp, imaging, and biochemical methodology, the physiology of identified, in terms of peptide secreted, nerve terminals in conjunction with their differential release of neuropeptides. In particular we propose to characterize in detail the Ca2+ channels, including verification, at the single channel level, of the kinetics and pharmacology of the controversial "Q" -type, found at these nerve terminals. We will localize the different neurohypophysial Ca2+ channels between types of terminals and within individual terminals in relation to possible release sites. Finally, we will determine which types are important for the release of vasopressin vs oxytocin. Elucidation of the molecular mechanisms underlying such interactions will represent a major advance in the understanding of how neuronal communication is regulated.