DEPOLARIZATION-SECRETION COUPLING IN NERVE TERMINALS

描述 神经递质的释放是轴突刺突侵入神经的结果 terminals. 虽然有相当多的证据表明， 神经元胞体导致Ca+的进入和随后的分泌， 神经递质和/或神经激素，离子如何 电流控制神经末梢释放神经活性物质 仍然无法确定。 该提议利用了哺乳动物系统， 这些问题可以直接解决。 我们已经知道了很多 关于大鼠神经垂体的电活动和随后的 肽类激素，加压素和催产素的释放， 表征了 现在，制备分离的神经 从这个神经内分泌结构的终端，响应去极化 通过Ca 2+依赖性胞吐作用释放鉴定的肽。 此外，从神经垂体的释放是由特定的 电活动的模式。 因此，这些神经末梢具有 必要的属性来详细分析的过程中， 去极化-分泌偶联（神经肽如何在 对神经终末膜的去极化的响应）。 我们建议 研究，使用复杂的膜片钳，成像和生化 方法学，生理学鉴定，在肽分泌方面， 神经末梢与它们的差异释放 神经肽 特别是，我们建议详细描述Ca 2 + 渠道，包括在单渠道一级核查 有争议的“Q”型的动力学和药理学，发现在这些 神经末梢 我们将定位不同的神经垂体Ca 2 + 不同类型终端之间以及单个终端内部的通道， 可能的释放地点。 最后，我们将确定哪些类型 对后叶加压素和催产素的释放都很重要。 阐明 这种相互作用的分子机制将代表一个主要的 在了解神经元通信是如何调节的进步。

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.