Bernard V, Somogyi P, Bolam J P
University Department of Pharmacology, Oxford University, United Kingdom.
J Neurosci. 1997 Jan 15;17(2):819-33. doi: 10.1523/JNEUROSCI.17-02-00819.1997.
Glutamate released in the basal ganglia is involved in the expression of clinical symptoms of neurodegenerative diseases like Parkinson's or Huntington's. Neostriatal neurons are the targets of glutamatergic inputs derived from the cortex and the thalamus acting via AMPA-type as well as other glutamate receptors. To determine the location of subunits of the AMPA subclass of glutamate receptors (GluR) in the rat neostriatum, we applied multiple immunocytochemical techniques using anti-peptide antibodies against the GluR1, GluR2/3, and GluR4 subunits at both the light and electron microscopic levels. All medium spiny efferent neurons, some of which were identified as striatonigral neurons, displayed immunoreactivity for GluR1 and GluR2/3 subunits. Double immunofluorescence revealed that at least 70-90% of parvalbumin-immunopositive GABAergic interneurons were immunoreactive for each of GluR1, GluR2/3, or GluR4 subunits and that at least 40% of choline acetyltransferase-immunopositive cholinergic interneurons were immunopositive for GluR1 or GluR4 subunits. The majority of nitric oxide synthase-immunopositive neurons had no detectable immunoreactivity for any of the AMPA receptor subunits. Electron microscopic analysis confirmed the presence of immunoreactivity for GluR1 and GluR2/3 in the perikarya of spiny neurons and interneurons and GluR4 in perikarya of interneurons only. GluR1 and GluR2/3 subunits were detected in dendrites and spines. A significant population of extrasynaptic receptors was revealed by pre-embedding immunogold labeling along the plasma membranes of perikarya, dendrites, and spines. Receptors were concentrated in the postsynaptic membrane specialization of asymmetrical synapses, as revealed by the postembedding immunogold method. Quantitative analysis demonstrated that immunoreactivity for the GluR1 and GluR2/3 subunits is higher at the periphery than at the middle of the postsynaptic membrane specialization. Our results demonstrate that AMPA receptor subunits are distributed widely and heterogeneously among striatal neurons and are concentrated on the postsynaptic membrane of asymmetrical synaptic specializations, although extrasynaptic receptors are also present.
基底神经节中释放的谷氨酸参与帕金森氏症或亨廷顿氏症等神经退行性疾病临床症状的表现。新纹状体神经元是来自皮层和丘脑的谷氨酸能传入神经的靶标，这些传入神经通过AMPA型以及其他谷氨酸受体发挥作用。为了确定大鼠新纹状体中谷氨酸受体（GluR）AMPA亚类亚基的位置，我们在光学和电子显微镜水平上应用了多种免疫细胞化学技术，使用针对GluR1、GluR2/3和GluR4亚基的抗肽抗体。所有中等棘状传出神经元，其中一些被鉴定为纹状体黑质神经元，对GluR1和GluR2/3亚基均显示免疫反应性。双重免疫荧光显示，至少70 - 90%的小白蛋白免疫阳性GABA能中间神经元对GluR1、GluR2/3或GluR4亚基中的每一个均有免疫反应性，并且至少40%的胆碱乙酰转移酶免疫阳性胆碱能中间神经元对GluR1或GluR4亚基呈免疫阳性。大多数一氧化氮合酶免疫阳性神经元对任何AMPA受体亚基均无可检测到的免疫反应性。电子显微镜分析证实，棘状神经元和中间神经元的胞体中存在对GluR1和GluR2/3的免疫反应性，而仅在中间神经元的胞体中存在对GluR4的免疫反应性。在树突和棘中检测到了GluR1和GluR2/3亚基。通过包埋前免疫金标记在胞体、树突和棘的质膜上发现了大量的突触外受体。如包埋后免疫金法所示，受体集中在不对称突触的突触后膜特化部位。定量分析表明，GluR1和GluR2/3亚基的免疫反应性在突触后膜特化部位的周边高于中间。我们的结果表明，AMPA受体亚基在纹状体神经元中广泛且异质性分布，并且集中在不对称突触特化的突触后膜上，尽管也存在突触外受体。
