Hanson J E, Smith Y
Division of Neuroscience, Yerkes Regional Primate Research Center and Department of Neurology, Emory University, Atlanta, Georgia 30329, USA.
J Neurosci. 1999 Aug 1;19(15):6488-96. doi: 10.1523/JNEUROSCI.19-15-06488.1999.
Recent data showed that group I metabotropic glutamate receptors (mGluRs) are located perisynaptic to the postsynaptic specializations of asymmetric glutamatergic synapses in the cerebellum and hippocampus in rats. In the present study, we used immunogold labeling to elucidate the subsynaptic localization of group I mGluRs (mGluR1a and mGluR5) in the internal and external segments of the globus pallidus in monkeys. In contrast to hippocampal and cerebellar neurons, which receive massive glutamatergic inputs, dendrites of pallidal neurons are covered with GABAergic boutons from the striatum intermingled with a small proportion of glutamatergic terminals arising largely from the subthalamic nucleus. In line with previous data, mGluR1a and mGluR5 immunoreactivity was found at the edge of the postsynaptic specializations of asymmetric synapses established by subthalamic-like boutons in the monkey pallidum. However, a large proportion of gold particles were also seen in the main body of the postsynaptic specializations of symmetric synapses formed by striatal GABAergic terminals. These data raise questions about the possible sources of activation of these receptors and the potential roles of group I mGluRs in modulating GABAergic neurotransmission at striatopallidal synapses.
最近的数据显示，I 型代谢型谷氨酸受体（mGluRs）位于大鼠小脑和海马体中不对称谷氨酸能突触的突触后特化结构的突触周围。在本研究中，我们使用免疫金标记法来阐明 I 型 mGluRs（mGluR1a 和 mGluR5）在猴苍白球内、外段的突触下定位。与接受大量谷氨酸能输入的海马体和小脑神经元不同，苍白球神经元的树突被来自纹状体的γ-氨基丁酸能（GABAergic）终扣所覆盖，这些终扣中还夹杂着一小部分主要来自丘脑底核的谷氨酸能终末。与之前的数据一致，在猴苍白球中，由类似丘脑底核的终扣形成的不对称突触的突触后特化结构边缘发现了 mGluR1a 和 mGluR5 的免疫反应性。然而，在由纹状体 GABA 能终末形成的对称突触的突触后特化结构主体中也发现了大量的金颗粒。这些数据引发了关于这些受体可能的激活来源以及 I 型 mGluRs 在调节纹状体苍白球突触处 GABA 能神经传递中的潜在作用的问题。
