GLUTAMATE-LIKE IMMUNOREACTIVITY IN RETINAL TERMINALS OF THE MOUSE SUPRACHIASMATIC NUCLEUS
GLUTAMATE-LIKE IMMUNOREACTIVITY IN RETINAL TERMINALS OF THE MOUSE SUPRACHIASMATIC NUCLEUS
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DOI：
10.1111/j.1460-9568.1993.tb00504.x
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发表时间：
1993-04-01
影响因子：
3.4
通讯作者：
STORMMATHISEN, J
中科院分区：
文献类型：
--
作者：
CASTEL, M;BELENKY, M;STORMMATHISEN, J
为了确定小鼠视交叉上核视网膜末梢的神经递质含量，在超微结构水平上使用了一种对戊二醛偶联谷氨酸具有高度特异性的抗血清。通过霍乱毒素-辣根过氧化物酶从视网膜顺行运输并与四甲基联苯胺/钨酸盐/H2O2反应，或通过其特有的苍白和膨胀的线粒体以及不规则的嵴来鉴定视网膜终末。对照包括含有高浓度各种氨基酸的模型超薄切片。交替连续切片用抗谷氨酸和抗γ -氨基丁酸（GABA）标记。数据通过计算机辅助图像分析进行分析。整个视网膜末端谷氨酸标记密度（每mum2金粒）比突触后树突高3倍，比视交叉上核其他非视网膜非谷氨酸末端高5倍。视网膜末端的金颗粒总体密度约为gaba末端的3倍，其中谷氨酸样免疫反应主要是线粒体。视网膜末端小泡的标记几乎是gaba末端小泡明显标记的5倍，强调了递质谷氨酸在视网膜末端突触小泡中的位置。在视交叉上核的视网膜受体区域也有一小部分非视网膜谷氨酸末端。它们的整体免疫反应性与视网膜末梢相似或超过视网膜末梢，但两种含谷氨酸末梢的形态学特征明显不同。目前的结果表明，绝大多数视网膜终末可能使用谷氨酸作为递质，与其他来源的电生理学和神经药理学数据保持一致。在含有谷氨酸的突触囊泡中存在密集核囊泡，这表明视网膜终末内共递质的可能性仍有待解决。
With a view to identifying the neurotransmitter content of retinal terminals within the mouse suprachiasmatic nucleus, a highly specific antiserum to glutaraldehyde-coupled glutamate was used in a postembedding immunogold procedure at the ultrastructural level. Retinal terminals were identified by cholera toxin - horseradish peroxidase transported anterogradely from the retina and reacted with tetramethyl benzidine/tungstate/H2O2, or by their characteristically pale and distended mitochondria with irregular cristae. Controls included model ultrathin sections containing high concentrations of various amino acids. Alternate serial sections were labelled with anti-glutamate and anti-gamma-aminobutyric acid (GABA). Data were analysed by computer-assisted image analysis. Density of glutamate labelling (gold particles per mum2) on whole retinal terminals was > 3 times higher than that on postsynaptic dendrites, and > 5 times higher than that on miscellaneous non-retinal non-glutamatergic terminals in the suprachiasmatic nucleus. The overall density of gold particles over retinal terminals was approximately 3 times higher than that over GABAergic terminals, in which glutamate-like immunoreactivity was mainly mitochondrial. Labelling of vesicles in retinal terminals was almost 5 times greater than the apparent Labelling of vesicles in GABAergic terminals, underscoring the location of transmitter glutamate within synaptic vesicles in retinal terminals. In the retino-recipient region of the suprachiasmatic nucleus there was also a small population of non-retinal glutamatergic terminals. Their overall immunoreactivity was similar to or exceeded that of retinal terminals, but morphological features clearly distinguished between these two types of glutamate-containing terminals. The present results indicate that the vast majority of retinal terminals may use glutamate as a transmitter, in keeping with electrophysiological and neuropharmacological data from other sources. The possibility of cotransmitters within retinal terminals, suggested by the presence of dense-core vesicles among the glutamate-containing synaptic vesicles, has still to be addressed.