Kharazia V N, Wenthold R J, Weinberg R J
Department of Cell Biology and Anatomy, University of North Carolina, Chapel Hill 27599, USA.
J Comp Neurol. 1996 May 6;368(3):399-412. doi: 10.1002/(SICI)1096-9861(19960506)368:3<399::AID-CNE6>3.0.CO;2-0.
Recent in vitro studies suggest that inhibitory interneurons in cortex may express the GluR1 glutamate receptor subunit in the absence of GluR2, leading to calcium-permeable alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) channels. We performed a study of rat somatic sensory cortex to confirm and extend these observations, using quantitative immunocytochemistry for multiple antigens. A morphologically distinct subpopulation of nonpyramidal neurons in neocortex was intensely immunoreactive for GluR1. Electron microscopic analysis of these cells revealed somatic staining for GluR1, mainly in the rough endoplasmic reticulum. Dendritic staining was concentrated at the synaptic active zone and in the adjacent subsynaptic cytoplasm. Double immunostaining revealed that the large majority of intensely GluR1-positive cells contained gamma-aminobutyric acid or its synthetic enzyme, glutamic acid decarboxylase, but little or no GluR2. Thus, AMPA receptors on a subpopulation of inhibitory interneurons in cortex are likely to be calcium permeable. This calcium permeability is likely to influence functional properties of these neurons; it may underlie the high levels of calcium-binding proteins they contain; and may render them liable to excitotoxic injury
最近的体外研究表明，皮质中的抑制性中间神经元可能在缺乏GluR2的情况下表达GluR1谷氨酸受体亚基，从而导致钙通透性α-氨基-3-羟基-5-甲基异恶唑-4-丙酸（AMPA）通道。我们利用针对多种抗原的定量免疫细胞化学技术，对大鼠躯体感觉皮质进行了一项研究，以证实并扩展这些观察结果。新皮质中一个形态学上独特的非锥体神经元亚群对GluR1具有强烈的免疫反应性。对这些细胞的电子显微镜分析显示，GluR1的体细胞染色主要位于粗面内质网中。树突染色集中在突触活动区和相邻的突触下细胞质中。双重免疫染色显示，绝大多数强烈的GluR1阳性细胞含有γ-氨基丁酸或其合成酶谷氨酸脱羧酶，但几乎没有或没有GluR2。因此，皮质中抑制性中间神经元亚群上的AMPA受体可能具有钙通透性。这种钙通透性可能会影响这些神经元的功能特性；它可能是它们所含高水平钙结合蛋白的基础；并且可能使它们易受兴奋性毒性损伤。
