MECHANISMS OF NEUROSECRETION

钙离子在神经递质释放的控制中起着核心作用 和突触传递。卡茨的开创性工作， Miledi对神经肌肉接头的研究表明，钙离子必须是 存在于突触前去极化线，如果发射器释放是 发生和突触后电位的大小（一种测量 释放的神经递质的量）是神经递质的量的函数。 钙通过电压依赖性通道进入突触前。 过去几年的发展表明，他们的某些人 然而，这些结论可能并不普遍适用于所有的突触。 例如，在中枢神经元之间的某些突触上的传输是 被认为是不依赖钙的。在其他情况下，变送器释放可能不会 是量子的。这些观察结果表明，可能不止一个 负责释放发射器的机制，一个想法是， 最近的证据表明，肽的分泌可能不同， 基本上来自于经典神经递质的分泌。此外，委员会认为， 已经清楚存在几种不同的钙通道类型， 提出了关于哪种钙通道调节胞吐作用的问题， 不同类型的钙通道是否可能与 不同类型的发射机。背根神经节神经元的体外培养 是研究这些问题的理想准备 因为它们至少有三种电压依赖性钙离子 通道和合成，储存和释放肽和经典的 发射器利用生物化学电生理学和药理学 技术，我们将比较几个方面的释放机制， 背根神经节分离培养中P物质和谷氨酸 神经元这些结果可能会提供重要的见解， 神经元和它们的目标之间的通信机制。

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.