MECHANISMS OF NEUROSECRETION

钙离子在神经递质释放的控制中起着核心作用 以及大多数系统中的突触传递。卡茨和他的开创性工作 Miledi对神经肌肉接头的研究表明，钙离子必须是 出现在突触前去极化线，如果递质释放 以及突触后电位的大小(一种衡量 神经递质的释放量)是 钙离子通过电压依赖的通道进入突触前。 过去几年的发展表明，他们的某些人 然而，结论可能并不是所有突触都适用的。 例如，一些突触在中枢神经元之间的传递是 被认为是不依赖钙的。在其他情况下，发射机释放可能不会 做一个量化的人。这些观察结果表明，可能存在不止一个 负责发射器释放的机制，这是一个想法 最近有证据表明，多肽的分泌可能不同 主要来自经典神经递质的分泌。此外， 已经很清楚存在几种不同的钙通道类型， 提出了哪些钙通道调节胞吐作用的问题，以及 不同类型的钙通道是否可能偶联到释放 不同类型的发射机。背根神经节神经元的体外培养 构成了研究这些问题的理想准备 因为它们至少表现出三种电压依赖性钙 引导和合成、储存和释放多肽和经典多肽 发射机。使用生化、电生理和药理学 技术，我们将比较以下几个方面的释放机制 背根神经节游离培养中P物质和谷氨酸的变化 神经元。这些结果可能会为我们提供对 神经元和它们的靶子之间通信的潜在机制。

Calcium ions play a central role in the control of neurotransmitter release and synaptic transmission in most systems. The pioneering work of Katz and Miledi on the neuromuscular junction demonstrated that calcium ions must be present at the line of presynaptic depolarization if transmitter release is to occur and that the size of the postsynaptic potential (a measure of the quantity of neurotransmitter released) is a function of the amount of calcium entering presynaptically through voltage-dependent channels. Developments in past several years suggest that certain of their conclusions, however, may not be universally applicable to all synapses. Transmission at some synapses between central neurons, for example, is thought to be calcium-independent. At others, transmitter release may not be quantal. These observations suggest that there may be more than one mechanism responsible for the release of transmitter, an idea that is supported by recent evidence that secretion of peptides may differ fundamentally from secretion of classical neurotransmitters. Furthermore, it has become clear that several different calcium channel types exist, raising questions as to which calcium channel regulates exocytosis, and whether different types of calcium channel might be coupled to the release of different types of transmitter. Dorsal root ganglion neurons in vitro constitute an ideal preparation in which to investigate these questions because they exhibit at least three types of voltage-dependent calcium channel and synthesize, store, and release both peptides and classical transmitters. Using biochemical, electrophysiological, and pharmacological techniques we will compare several aspects of the release mechanisms for substance P and glutamate in dissociated cultures of dorsal root ganglion neurons. The results are likely to provide significant insights into the mechanisms underlying the communication between neurons and their targets.