Excitatory amino acids inhibit stimulation of phosphatidylinositol metabolism by aminergic agonists in hippocampus
Excitatory amino acids inhibit stimulation of phosphatidylinositol metabolism by aminergic agonists in hippocampus
复制标题
兴奋性氨基酸抑制海马中胺能激动剂对磷脂酰肌醇代谢的刺激
作者：
M. Baudry;Jim E. Evans;G. Lynch
自20世纪50年代首次观察以来1，2大量神经递质和激素已被证明影响脑和外周神经节中的磷脂酰肌醇（PI）代谢（综述见参考文献3）。这导致了建议，PI是细胞内的第二信使系统的某些类型的扩散化学factors 4，5的一部分。与此相一致的是最近的报道，PI周转的产物之一（二酰基甘油）刺激钙依赖性磷脂依赖性蛋白激酶（激酶C），而第二个（三磷酸肌醇）导致钙从细胞内储存释放6，7。因此，至少有一些脑神经递质可能利用PI系统产生功能效应，这些功能效应是它们引起的非常短暂的生理反应的补充，并且比它们引起的非常短暂的生理反应持续时间更长。尽管已经预期另一类受体可能抑制受体介导的PI分解刺激，但尚未描述此类效应的明确实例。我们现在报告说，酸性氨基酸，这被认为是兴奋性神经递质在大多数脑突触8，强烈抑制刺激PI代谢引起的卡巴胆碱，组胺，或钾诱导的去极化，而不改变反应去甲肾上腺素。这些结果不仅表明兴奋性氨基酸具有新的功能，还表明中枢神经系统具有以前未被怀疑的细胞-细胞相互作用。
Since the initial observations in the 1950s1,2 a large number of neurotransmitters and hormones have been shown to influence phosphatidylinositol (PI) metabolism in brain and peripheral ganglia (see ref. 3 for review). This has led to the suggestion that PI is part of an intracellular second messenger system for some types of diffusible chemical factors4,5. Consistent with this are recent reports that one of the products of PI turnover (diacylgly-cerol) stimulates the Ca-dependent phospholipid-dependent protein kinase (kinase C) while a second (inositol trisphosphate) causes the release of calcium from intracellular stores6,7. Thus it is possible that at least some brain neurotransmitters utilize the PI system to produce functional effects that are in addition to and which outlast the very brief physiological responses they elicit. Although it had been anticipated that another class of receptors might inhibit receptor-mediated stimulation of PI breakdown, no clear examples of such effects have been described. We now report that acidic amino acids, which are thought to be excitatory neurotransmitters at the majority of brain synapses8, strongly inhibit the stimulation of PI metabolism elicited by carbachol, histamine, or by potassium-induced depolarization, without changing the response to noradrenaline. As well as indicating a novel function for the excitatory amino acids, these results suggest that the central nervous system possesses cell-cell interactions of a previously unsuspected type.