Selective excitatory amino acid uptake in glutamatergic nerve terminals and in glia in the rat striatum: Quantitative electron microscopic immunocytochemistry of exogenous D-aspartate and endogenous glutamate and GABA
Selective excitatory amino acid uptake in glutamatergic nerve terminals and in glia in the rat striatum: Quantitative electron microscopic immunocytochemistry of exogenous D-aspartate and endogenous glutamate and GABA
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DOI：
10.1111/j.1460-9568.1996.tb01261.x
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发表时间：
1996-04-01
影响因子：
3.4
通讯作者：
StormMathisen, J
中科院分区：
文献类型：
--
作者：
Gundersen, V;Ottersen, OP;StormMathisen, J
为了表征纹状体中各种细胞和亚细胞元素中谷氨酸/天冬氨酸摄取活性，大鼠纹状体切片暴露于10和50 μ M外源性D-天冬氨酸。戊二醛/甲醛固定后，用免疫细胞化学方法分析D-天冬氨酸的分布，并与内源性谷氨酸和GABA的分布进行比较。光镜下，D-天冬氨酸样免疫反应定位于沿着标记非常弱的树突状细胞和神经元细胞体的明显圆点。在电子显微镜水平，金颗粒信号D-天冬氨酸发生在最高密度的神经末梢，使不对称的接触突触后棘（即类似于皮层传入神经的突触）。星形胶质细胞突起也含有金颗粒，但密度低于神经末梢。相反，树突棘只有弱D-天冬氨酸阳性。在10和50 μ M D-天冬氨酸标记的差异是一致的“高亲和力”的吸收。相邻的部分与其他抗体处理表明，D-天冬氨酸标记发生在神经末梢强烈的谷氨酸免疫反应，而不是在终端非常弱的谷氨酸免疫阳性或GABA免疫反应的神经末梢。谷氨酸标记的灌注固定纹状体证实，终端形成不对称的突触接触与棘富含金颗粒，这表明这些终端使用谷氨酸作为一种传输器。这项研究表明，高亲和力的兴奋性氨基酸在纹状体的摄取网站上最强烈地表达在假定的多巴胺能神经末梢和星形胶质细胞。
To characterize glutamate/aspartate uptake activity in various cellular and subcellular elements in the striatum, rat striatal slices were exposed to 10 and 50 mu M exogenous D-aspartate. After fixation with glutaraldehyde/formaldehyde the distribution of D-aspartate was analysed by postembedding immunocytochemistry and the ultrastructural distribution was compared with the distributions of endogenous glutamate and GABA. Light microscopically, D-aspartate-like immunoreactivity was localized in conspicuous dots along very weakly labelled dendritic profiles and neuron cell bodies. At the electron microscope level gold particles signalling D-aspartate occurred at highest density in nerve terminals making asymmetrical contacts with postsynaptic spines (i.e. resembling synapses of cortical afferents). Astrocytic processes also contained gold particles, but at a lower density than nerve endings. In contrast, dendritic spines were only weakly D-aspartate-positive. The difference in labelling at 10 and 50 mu M D-aspartate was consistent with 'high-affinity' uptake. Neighbouring sections processed with other antibodies showed that the D-aspartate labelling occurred in nerve terminals strongly immunoreactive for glutamate, rather than in terminals very weakly glutamate-immunopositive or in nerve endings immunoreactive for GABA. Glutamate labelling of perfusion-fixed striatum confirmed that terminals forming asymmetrical synaptic contacts with spines were enriched with gold particles, suggesting that these terminals use glutamate as a transmitter. This study demonstrates that high-affinity uptake sites for excitatory amino acids in the striatum are most strongly expressed on presumed glutamatergic nerve terminals and on astrocytes.