Kohama S G, Urbanski H F
Division of Neurosciences, Oregon Regional Primate Research Center, Beaverton 97006, USA.
Brain Res. 1997 Sep 19;769(1):44-56. doi: 10.1016/s0006-8993(97)00686-0.
The distribution of subunits for the N-methyl-D-aspartate (NR1, NR2A/B), alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (GluR1, GluR2/3, GluR4) and low affinity kainate (GluR5/6/7) ionotropic glutamate receptors was examined by immunocytochemistry in the temporal cortex and hippocampus of the rhesus macaque (Macaca mulatta). Neurons expressing NR1, NR2A/B, GluR2/3, and GluR4 subunits were widely distributed in all of the cortical layers but the overall density of the GluR4-immunopositive neurons was very low. Neurons expressing the GluR1 subunit were found predominantly in cortical layers V and VI while those expressing the GluR5/6/7 subunits were concentrated in layer V and were readily distinguishable by the thick elongate shape of their primary apical dendrites. Subcellular differences in the immunostaining pattern were also noted between the different glutamate receptor subunits. NR1 and NR2A/B immunoreactivity was most pronounced in somatic and primary dendritic compartments and to a lesser extent in cortical and hippocampal molecular layers. GluR1 immunoreactivity was more intense than GluR2/3 in the hippocampal molecular layers whereas GluR4 was undetectable. GluR5/6/7 immunoreactivity was very intense in the dentate molecular layer, and the CA1 pyramidal cells had a subcellular distribution of GluR5/6/7 that was similar to the cortical neurons. Overall, the distribution patterns of the different glutamate receptor subunits was identical in animals that had been ovariectomized and in ovariectomized animals that had subsequently undergone estradiol or estradiol/progesterone hormone replacement. Taken together, these findings demonstrate a differential spatial arrangement of glutamate receptor subunits in the primate temporal cortex and hippocampus, which may have functional significance for the integration of excitatory inputs to these areas. Furthermore, they show that in adult macaques, sex steroids do not play a major role in determining the distribution patterns of these receptor subunits.
通过免疫细胞化学方法，对恒河猴（猕猴）颞叶皮质和海马中N-甲基-D-天冬氨酸（NR1、NR2A/B）、α-氨基-3-羟基-5-甲基-4-异恶唑丙酸（GluR1、GluR2/3、GluR4）和低亲和力红藻氨酸（GluR5/6/7）离子型谷氨酸受体亚基的分布进行了研究。表达NR1、NR2A/B、GluR2/3和GluR4亚基的神经元广泛分布于所有皮质层，但GluR4免疫阳性神经元的总体密度非常低。表达GluR1亚基的神经元主要位于皮质V层和VI层，而表达GluR5/6/7亚基的神经元集中在V层，其主要顶端树突的粗大细长形状很容易区分。不同谷氨酸受体亚基之间在免疫染色模式上也存在亚细胞差异。NR1和NR2A/B免疫反应性在体细胞和初级树突部分最为明显，在皮质和海马分子层中程度较轻。在海马分子层中，GluR1免疫反应性比GluR2/3更强，而GluR4无法检测到。GluR5/6/7免疫反应性在齿状分子层中非常强烈，CA1锥体细胞中GluR5/6/7的亚细胞分布与皮质神经元相似。总体而言，在去卵巢动物以及随后接受雌二醇或雌二醇/孕酮激素替代的去卵巢动物中，不同谷氨酸受体亚基的分布模式是相同的。综上所述，这些发现表明灵长类动物颞叶皮质和海马中谷氨酸受体亚基存在不同的空间排列，这可能对这些区域兴奋性输入的整合具有功能意义。此外，研究表明在成年猕猴中，性类固醇在决定这些受体亚基的分布模式方面不起主要作用。
