Jojich L, Pourcho R G
Department of Anatomy and Cell Biology, Wayne State University, Detroit, MI 48201, USA.
Vis Neurosci. 1996 Jan-Feb;13(1):117-33. doi: 10.1017/s0952523800007173.
Immunocytochemical methods were used to visualize glutamate immunoreactivity in the cat retina and to compare its localization with that of aspartate, GABA, and glycine. The cellular and subcellular distribution of glutamate was analyzed at the light-microscopic level by optical densitometry and at the electron-microscopic level by immunogold quantification. The findings were consistent with the proposed role for glutamate as the neurotransmitter of photoreceptors and bipolar cells as particularly high concentrations of staining were found in synaptic terminals of these cells. Ganglion cells were also consistently stained. Aspartate was totally colocalized with glutamate in neuronal cell bodies but the synaptic levels of aspartate were much lower than for glutamate. In addition to the staining of photoreceptor, bipolar, and ganglion cells, glutamate immunoreactivity was also observed in approximately 60% of the amacrine cells. These cells exhibited colocalization with either GABA or glycine. The elevated levels of Glu in amacrine cells may reflect its role as a transmitter precursor in GABAergic cells and as an energy source for mitochondria in glycinergic cells.
采用免疫细胞化学方法观察猫视网膜中谷氨酸免疫反应性，并将其定位与天冬氨酸、γ-氨基丁酸（GABA）和甘氨酸的定位进行比较。通过光密度测定法在光学显微镜水平分析谷氨酸的细胞和亚细胞分布，并通过免疫金定量法在电子显微镜水平进行分析。研究结果与谷氨酸作为光感受器和双极细胞神经递质的推测作用一致，因为在这些细胞的突触终末发现了特别高浓度的染色。神经节细胞也始终被染色。天冬氨酸在神经元细胞体中与谷氨酸完全共定位，但天冬氨酸的突触水平远低于谷氨酸。除了光感受器、双极细胞和神经节细胞的染色外，在约60%的无长突细胞中也观察到谷氨酸免疫反应性。这些细胞与GABA或甘氨酸共定位。无长突细胞中谷氨酸水平升高可能反映了其作为GABA能细胞中递质前体的作用以及作为甘氨酸能细胞中线粒体能量来源的作用。
