Lin Li-Hsien, Talman William T
Veterans Affairs Medical Center, Department of Neurology, University of Iowa, 3-278, MS 151, Iowa City 52246, USA.
J Chem Neuroanat. 2002 Nov;24(4):287-96. doi: 10.1016/s0891-0618(02)00069-8.
We previously showed that most neuronal nitric oxide synthase (nNOS)-containing neurons in the nucleus tractus solitarii (NTS) contain NMDAR1, the fundamental subunit for functional N-methyl-D-aspartate (NMDA) receptors. Likewise, we found that almost all nNOS-containing neurons in the NTS contain GluR1, the calcium permeable AMPA receptor subunit. These data suggest that AMPA and NMDA receptors may colocalize in NTS neurons that contain nNOS. However, other investigators have suggested that non-NMDA receptors are located primarily on second-order neurons and NMDA receptors are located predominantly on higher-order neurons in NTS. We now seek to test the hypothesis that NMDA receptors, AMPA receptors and nNOS are colocalized in NTS cells. We performed triple fluorescent immunohistochemical staining of nNOS, NMDAR1 and GluR1, and performed confocal laser scanning microscopic analysis of the NTS. The distributions of nNOS immunoreactivity (IR), NMDAR1-IR and GluR1-IR in the NTS were similar to those we reported earlier. Superimposed images revealed that almost all NMDAR1-IR cells contained GluR1-IR and almost all GluR1-IR cells contained NMDAR1-IR. Some double-labeled cells were additionally labeled for nNOS-IR. All nNOS-IR neurons contained both GluR1-IR and NMDAR1-IR. These studies support our hypothesis that NMDA and AMPA receptors are colocalized in NTS neurons and are consistent with a role of both types of ionotropic receptors in transmission of afferent signals in NTS. In addition, these data provide support for an anatomical link between ionotropic glutamate receptors and nitric oxide in the NTS.
我们之前的研究表明，孤束核（NTS）中大多数含有神经元型一氧化氮合酶（nNOS）的神经元都含有NMDAR1，它是功能性N-甲基-D-天冬氨酸（NMDA）受体的基本亚基。同样，我们发现NTS中几乎所有含有nNOS的神经元都含有GluR1，即钙通透性AMPA受体亚基。这些数据表明，AMPA和NMDA受体可能共定位于含有nNOS的NTS神经元中。然而，其他研究者认为，非NMDA受体主要位于二级神经元上，而NMDA受体主要位于NTS中的高级神经元上。我们现在试图验证NMDA受体、AMPA受体和nNOS在NTS细胞中共定位的假说。我们对nNOS、NMDAR1和GluR1进行了三重荧光免疫组织化学染色，并对NTS进行了共聚焦激光扫描显微镜分析。NTS中nNOS免疫反应性（IR）、NMDAR1-IR和GluR1-IR的分布与我们之前报道的相似。叠加图像显示，几乎所有NMDAR1-IR细胞都含有GluR1-IR，几乎所有GluR1-IR细胞都含有NMDAR1-IR。一些双标记细胞还被标记了nNOS-IR。所有nNOS-IR神经元都同时含有GluR1-IR和NMDAR1-IR。这些研究支持了我们的假说，即NMDA和AMPA受体在NTS神经元中共定位，并且与这两种离子型受体在NTS传入信号传递中的作用一致。此外，这些数据为NTS中离子型谷氨酸受体与一氧化氮之间的解剖学联系提供了支持。
