Martin L J, Blackstone C D, Levey A I, Huganir R L, Price D L
Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, Maryland.
Neuroscience. 1993 Mar;53(2):327-58. doi: 10.1016/0306-4522(93)90199-p.
To demonstrate the regional, cellular and subcellular distributions of non-N-methyl-D-aspartate glutamate receptors in rat brain, we generated antipeptide antibodies that recognize the C-terminal domains of individual subunits of the alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA)-preferring glutamate receptors (i.e. GluR1, GluR4, and a region highly conserved in GluR2, GluR3 and GluR4c). On immunoblots, antibodies detect distinct proteins with mol. wts ranging from 102,000 to 108,000 in homogenates of rat brain. Immunocytochemistry shows that glutamate receptor subunits are distributed abundantly and differentially within neuronal cell bodies and processes in cerebral cortex, basal ganglia, limbic system, thalamus, cerebellum and brainstem. The precise patterns and cellular localizations of glutamate receptor subunit immunoreactivities are unique for each antibody. In neocortex and hippocampus, pyramidal neurons express GluR1 and GluR2/3/4c immunoreactivities; many non-pyramidal, calcium-binding, protein-enriched neurons in cerebral cortex are selectively immunoreactive for GluR1. In striatum, the cellular localizations of GluR1, GluR2/3/4c and GluR4 immunoreactivities are different; in this region, GluR1 co-localizes with many cholinergic neurons but is only present in a minor proportion of nicotinamide adenine dinucleotide phosphate diaphorase-positive striatal neurons. GluR1 co-localizes with most dopaminergic neurons within the substantia nigra. In several brain regions, astrocytes show GluR4 immunoreactivity. Within the cerebellar cortex, cell bodies and processes of Bergmann glia express intense GluR4 and GluR1 immunoreactivities; perikarya and dendrites of Purkinje cells show GluR2/3/4c immunoreactivity but no evidence of GluR1 or GluR4. Ultrastructurally, GluR subunit immunoreactivities are localized within cell bodies, dendrites and dendritic spines of specific subsets of neurons and, in the case of GluR1 and GluR4, in some populations of astrocytes. This investigation demonstrates that individual AMPA-preferring glutamate receptor subunits are distributed differentially in the brain and suggests that specific neurons and glial cells selectively express glutamate receptors composed of different subunit combinations. Thus, the co-expression of all AMPA receptor subunits within individual cells may not be obligatory for the functions of this glutamate receptor in vivo.
为了展示非 N-甲基-D-天冬氨酸谷氨酸受体在大鼠脑中的区域、细胞及亚细胞分布，我们制备了抗肽抗体，该抗体可识别α-氨基-3-羟基-5-甲基-4-异恶唑丙酸（AMPA）偏好型谷氨酸受体各亚基的 C 末端结构域（即 GluR1、GluR4，以及 GluR2、GluR3 和 GluR4c 中高度保守的区域）。在免疫印迹上，抗体可在大鼠脑匀浆中检测到分子量范围为 102,000 至 108,000 的不同蛋白质。免疫细胞化学显示，谷氨酸受体亚基在大脑皮质、基底神经节、边缘系统、丘脑、小脑和脑干的神经元细胞体及突起中大量且差异分布。每种抗体的谷氨酸受体亚基免疫反应性的精确模式和细胞定位都是独特的。在新皮质和海马中，锥体神经元表达 GluR1 和 GluR2/3/4c 免疫反应性；大脑皮质中许多非锥体、富含钙结合蛋白的神经元对 GluR1 具有选择性免疫反应性。在纹状体中，GluR1、GluR2/3/4c 和 GluR4 免疫反应性的细胞定位不同；在该区域，GluR1 与许多胆碱能神经元共定位，但仅存在于少数烟酰胺腺嘌呤二核苷酸磷酸黄递酶阳性的纹状体神经元中。GluR1 与黑质内的大多数多巴胺能神经元共定位。在几个脑区，星形胶质细胞显示 GluR4 免疫反应性。在小脑皮质内，伯格曼胶质细胞的细胞体和突起表达强烈的 GluR4 和 GluR1 免疫反应性；浦肯野细胞的胞体和树突显示 GluR2/3/4c 免疫反应性，但无 GluR1 或 GluR4 的证据。在超微结构上，GluR 亚基免疫反应性定位于特定神经元亚群的细胞体、树突和树突棘内，对于 GluR1 和 GluR4 而言，还存在于一些星形胶质细胞群体中。本研究表明，单个 AMPA 偏好型谷氨酸受体亚基在脑中差异分布，并提示特定的神经元和胶质细胞选择性表达由不同亚基组合构成的谷氨酸受体。因此，单个细胞内所有 AMPA 受体亚基的共表达对于该谷氨酸受体在体内的功能可能并非必需。
