Muscarinic acetylcholine receptor‐expression in astrocytes in the cortex of young and aged rats
Muscarinic acetylcholine receptor‐expression in astrocytes in the cortex of young and aged rats
复制标题
年轻和老年大鼠皮质星形胶质细胞中毒蕈碱乙酰胆碱受体的表达
作者：
E. A. Zee;G. I. Jong;A. Strosberg;P. Luiten
本报告描述了M35免疫反应的细胞和亚细胞分布模式，M35是一种针对纯化毒蕈碱乙酰胆碱受体蛋白的单克隆抗体，在年轻和老年大鼠大脑皮层的星形胶质细胞中产生。大多数M35阳性星形胶质细胞定位于皮层的浅层和胼胝体的一部分。在超微结构水平上，免疫沉淀定位于高尔基复合体，但细胞核、粗内质网、线粒体和微丝一般没有标记。标记也与细胞膜相关，尽管没有神经元结构中特有的免疫反应性突触后膜增厚。在30 - 34个月的衰老大鼠中，M35标记的星形胶质细胞数量增加了一倍，而在一半的动物中，同一区域的神经元染色略有减少。M35和星形细胞微丝蛋白GFAP的荧光双标记显示，所有M35阳性的胶质细胞都表达GFAP，相反，几乎所有GFAP胶质细胞都是M35免疫染色的。基于machr和GFAP共表达的高发生率，这两种蛋白可能在功能上相互连接。粗略的半定量估计显示，在年轻成年大鼠中，GFAP/M35‐免疫反应性星形胶质细胞约占所有皮质星形胶质细胞的五分之一。目前证明星形胶质细胞对mAChR蛋白的免疫反应性的一个重要方面是其原位标记而不是组织培养。这一发现可能进一步支持星形胶质细胞与神经元和血管成分的解剖关系及其在实验条件下的反应性的研究。©1993 Wiley‐Liss, Inc。
The present report describes the cellular and subcellular distribution pattern of immunoreactivity to M35, a monoclonal antibody raised against purified muscarinic acetylcholine receptor protein, in astrocytes in the cerebral cortex of young and aged rats. Most M35‐positive astrocytes were localized in the superficial layers of the cortex and part of the corpus callosum. At the ultrastructural level, immunoprecipitates were localized in the Golgi complexes, but the nucleus, rough endoplasmic reticulum, mitochondria, and microfilaments were generally free of labeling. Labeling was also present associated to the cell membrane, although without the characteristic immunoreactive postsynaptic membrane thickening found in neuronal structures. In aging rats of 30‐34 months, the number of M35‐labeled astrocytes doubled, whereas the neuronal staining slightly decreased in the same region in half of the animals studied. Fluorescent double‐labeling for M35 and GFAP, an astrocytic microfilament protein, revealed that all M35‐positive glial cells express GFAP and, conversely, that almost all GFAP glial cells were M35‐immunostained. Based on the high incidence of coexpression of mAChRs and GFAP, both proteins may be functionally linked to each other. Rough semiquantitative estimates revealed that in young adult rats the GFAP/M35‐immunoreactive astrocytes made up approximately one fifth of all cortical astrocytes. An important aspect of the presently demonstrated immunoreactivity of astroglia to mAChR proteins is its labeling in situ instead of in tissue culture. This finding may further support investigation, e.g., on anatomical relations of astroglia with neuronal and vascular elements, and its reactivity in experimental conditions. © 1993 Wiley‐Liss, Inc.