GLUTAMATE AS A CNS TRANSMITTER .1. EVALUATION OF GLUCOSE AND GLUTAMINE AS PRECURSORS FOR THE SYNTHESIS OF PREFERENTIALLY RELEASED GLUTAMATE
GLUTAMATE AS A CNS TRANSMITTER .1. EVALUATION OF GLUCOSE AND GLUTAMINE AS PRECURSORS FOR THE SYNTHESIS OF PREFERENTIALLY RELEASED GLUTAMATE
复制标题
DOI：
10.1016/0006-8993(79)90306-8
复制
发表时间：
1979-01-01
期刊：
影响因子：
2.9
通讯作者：
COTMAN, CW
中科院分区：
文献类型：
--
作者：
HAMBERGER, AC;CHIANG, GH;COTMAN, CW
用[14C]葡萄糖、[14C]丙酮酸或14C谷氨酰胺孵育大鼠海马齿状回分子层脑片，在不同条件下监测内源性谷氨酸和放射性谷氨酸的外流。在用[14C]谷氨酰胺或[14C]葡萄糖预先标记后，K+浓度升高到56 mM(无钙)会增加内源和[14C]-谷氨酸的外流。在K+浓度升高的培养液中加入Ca~(2+)进一步增加内源性谷氨酸和放射性谷氨酸的外流。在含谷氨酰胺的培养液中，谷氨酸外排和基础外排的增加明显高于不加谷氨酰胺的情况，释放的谷氨酸的比活性也高于组织内。谷氨酰胺优于葡萄糖或丙酮酸作为前体，并且最特异地标记了推测的谷氨酸传递体池。类似的实验在单侧内嗅觉皮质损伤后4天和14天进行，内嗅觉皮质为齿状颗粒细胞提供了约60%的突触输入。手术侧葡萄糖或谷氨酰胺对谷氨酸的钙依赖性释放明显减少。谷氨酸的传递池可能位于穿透通路末端，可由葡萄糖或谷氨酰胺合成。
Slices of the molecular layer of the rat dentate gyrus of the hippocampal formation were incubated with either [14C]glucose, [14C]pyruvate or 14C glutamine and the efflux of endogenous and radioactive glutamate was monitored under various conditions. After prelabeling with either [14C]glutamine or [14C]glucose elevation of K+ concentration to 56 mM (Ca2+ free) increased efflux of endogenous and [14C]-glutamate. Introduction of Ca2+ into the elevated K+ medium further increased the efflux of endogenous glutamate and radioactive glutamate derived from any of the precursors tested. In glutamine containing media, the increase in glutamate efflux and basal efflux was considerably higher than in the absence of glutamine and the specific activity of glutamate released was higher than that in the tissue. Glutamine was superior to glucose or pyruvate as precursor and most specifically labeled the putative transmitter pool of glutamate. Similar experiments were carried out 4 and 14 days after a unilateral lesion in the entorhinal cortex which provided about 60% of the total synaptic input to the dentate granule cells. The Ca2+ dependent release of glutamate derived from glucose or glutamine was markedly reduced on the operated side. The transmitter pool of glutamate is probably in perforant path terminals and can be synthesized from glucose or glutamine.