García-Barcina J M, Matute C
Departamento de Neurociencias, Facultad de Medicina y Odontoglia, Universidad del Pais Vasco, Leioa, Bizkaia, Spain.
Eur J Neurosci. 1996 Nov;8(11):2379-87. doi: 10.1111/j.1460-9568.1996.tb01201.x.
It is now well established that glial cells, like neurons, express a large variety of non-NMDA glutamate receptors. However, knowledge about the subunits forming the receptors and the types of glial cells which express them is incomplete. The aim of this study was to determine the presence and distribution of kainate-preferring glutamate receptor subunits in glial cells in the white matter of adult cattle. To this end, reverse transcription and polymerase chain reaction (RT-PCR) analysis of mRNA extracted from the corpus callosum, fornix and optic nerve of brains of adult cattle was carried out using specific primers that allowed selective amplification of the kainate transcripts for all five subunits were detected. Restriction digestion of the amplified products confirmed the specificity of the PCR amplifications and showed that the extent of Q/R editing in the GluR6 subunit was lower than that described in the rat whole brain. Immunohistochemical experiments revealed that GluR5-7 and KA2 subunits appeared in approximately 50% of astrocytes and 40% of oligodendrocytes. In astrocytes the receptor subunits were located throughout the cell body and processes, whereas in oligodendrocytes they were mostly restricted to the soma. Double-labelling studies demonstrated that in the white matter areas studied GluR5-7 and KA2 subunits are coexpressed in the majority of macroglial cell endowed with kainate receptors. In addition, astrocytes, but not oligodendrocytes, expressing kainate-selective receptors were found to possess the GluR1 subunit, an alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor subunit which has previously been found in this macroglial cell type. Taken together, these results provide evidence for the presence and molecular diversity of kainate-selective receptor subunits in glial cells of the adult white matter and for their coexpression with AMPA receptor subunits. The widespread distribution of kainate receptors in glial cells of the white matter suggests that these receptors may be important in axon-glia and/or glia-to-glia signalling.
现已充分证实，神经胶质细胞与神经元一样，表达多种非NMDA谷氨酸受体。然而，关于构成这些受体的亚基以及表达它们的神经胶质细胞类型的知识并不完整。本研究的目的是确定成年牛白质神经胶质细胞中偏好海人酸的谷氨酸受体亚基的存在和分布。为此，使用特异性引物对成年牛大脑胼胝体、穹窿和视神经中提取的mRNA进行逆转录和聚合酶链反应（RT-PCR）分析，这些引物能够选择性扩增所有五个亚基的海人酸转录本。对扩增产物进行限制性消化证实了PCR扩增的特异性，并表明GluR6亚基中的Q/R编辑程度低于大鼠全脑中描述的程度。免疫组织化学实验显示，GluR5 - 7和KA2亚基出现在约50%的星形胶质细胞和40%的少突胶质细胞中。在星形胶质细胞中，受体亚基分布于整个细胞体和突起，而在少突胶质细胞中，它们大多局限于胞体。双重标记研究表明，在所研究的白质区域中，GluR5 - 7和KA2亚基在大多数具有海人酸受体的大胶质细胞中共表达。此外，发现表达海人酸选择性受体的星形胶质细胞而非少突胶质细胞拥有GluR1亚基，GluR1是一种α-氨基-3-羟基-5-甲基-4-异恶唑丙酸（AMPA）受体亚基，此前已在这种大胶质细胞类型中发现。综上所述，这些结果为成年白质神经胶质细胞中海人酸选择性受体亚基的存在和分子多样性以及它们与AMPA受体亚基的共表达提供了证据。海人酸受体在白质神经胶质细胞中的广泛分布表明这些受体可能在轴突-神经胶质和/或神经胶质-神经胶质信号传导中起重要作用。
