Kerr R C, Maxwell D J, Todd A J
Laboratory of Human Anatomy, Institute of Biomedical and Life Sciences, University of Glasgow, UK.
Eur J Neurosci. 1998 Jan;10(1):324-33. doi: 10.1046/j.1460-9568.1998.00048.x.
GluR1 and GluR2 subunits of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptor are expressed at high levels by neurones in laminae I-III of rat spinal dorsal horn, an area which contains numerous, densely packed small neurones. In order to determine whether these subunits are expressed by inhibitory or excitatory neurones, we combined pre-embedding immunocytochemistry with antibodies that recognize either GluR1, or an epitope common to GluR2 and 3, with postembedding detection of gamma-aminobutyric acid (GABA) and glycine. Most (78%) of the neurones with GluR1-immunoreactivity were GABA-immunoreactive, and some of these were also glycine-immunoreactive, whereas nearly all (97%) of the GluR2/3-immunoreactive neurones were not GABA- or glycine-immunoreactive. We carried out double-immunofluorescence and confocal microscopy to provide further information on the neurochemistry of cells that express these subunits. As expected, all neurotensin- and virtually all somatostatin-immunoreactive cells (which are thought to be excitatory interneurones) were GluR2/3- but not GluR1-immunoreactive, whereas parvalbumin-containing cells (most of which are GABAergic) possessed GluR1-, but usually not GluR2/3-immunoreactivity. Neurones that contained nitric oxide synthase (most of which are GABAergic) were more variable, with 57% GluR1-immunoreactive and 41% GluR2/3-immunoreactive. Cholinergic neurones in lamina III (which are also GABAergic) invariably showed each type of GluR-immunoreactivity. These results suggest that neuronal populations in laminae I-III have characteristic patterns of GluR expression: GluR1 is particularly associated with inhibitory neurones, and GluR2 with excitatory neurones. This makes it likely that some of the AMPA receptors present on the inhibitory interneurones lack the GluR2 subunit, and may therefore have significant Ca2+-permeability.
α-氨基-3-羟基-5-甲基-4-异恶唑丙酸（AMPA）受体的GluR1和GluR2亚基在大鼠脊髓背角I-III层的神经元中高水平表达，该区域含有大量紧密排列的小神经元。为了确定这些亚基是由抑制性神经元还是兴奋性神经元表达，我们将包埋前免疫细胞化学与识别GluR1或GluR2和3共同表位的抗体相结合，并在包埋后检测γ-氨基丁酸（GABA）和甘氨酸。大多数（78%）具有GluR1免疫反应性的神经元是GABA免疫反应性的，其中一些也是甘氨酸免疫反应性的，而几乎所有（97%）具有GluR2/3免疫反应性的神经元都不是GABA或甘氨酸免疫反应性的。我们进行了双重免疫荧光和共聚焦显微镜检查，以提供关于表达这些亚基的细胞神经化学的进一步信息。正如预期的那样，所有神经降压素和几乎所有生长抑素免疫反应性细胞（被认为是兴奋性中间神经元）都是GluR2/3免疫反应性的，但不是GluR1免疫反应性的，而含小白蛋白的细胞（大多数是GABA能的）具有GluR1免疫反应性，但通常没有GluR2/3免疫反应性。含有一氧化氮合酶的神经元（大多数是GABA能的）变化更大，57%具有GluR1免疫反应性，41%具有GluR2/3免疫反应性。III层中的胆碱能神经元（也是GABA能的）总是表现出每种类型的GluR免疫反应性。这些结果表明，I-III层中的神经元群体具有特征性的GluR表达模式：GluR1特别与抑制性神经元相关，而GluR2与兴奋性神经元相关。这使得抑制性中间神经元上存在的一些AMPA受体可能缺乏GluR2亚基，因此可能具有显著的Ca2+通透性。
