Weiss S W, Albers D S, Iadarola M J, Dawson T M, Dawson V L, Standaert D G
Neurology Service, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114, USA.
J Neurosci. 1998 Mar 1;18(5):1725-34. doi: 10.1523/JNEUROSCI.18-05-01725.1998.
Nitric oxide (NO), an unconventional and diffusible neurotransmitter, is synthesized by nitric oxide synthase (NOS). NMDA glutamate receptors are potent regulators of NO synthesis. We have used dual-label immunofluorescence and confocal microscopy to examine forebrain neurons in the rat that contain high levels of neuronal NOS (nNOS) for the presence of the NMDAR1 receptor subunit protein and regions of this protein encoded by three alternative spliced segments of the NMDAR1 mRNA: N1, C1, and C2. In the neostriatum, neocortex, and hippocampus, nNOS-labeled neurons exhibit strong NMDAR1 immunoreactivity (-ir). In all three of these regions, nNOS-positive neurons are characterized by the absence of immunoreactivity for the C1 segment of NMDAR1, whereas C1-ir is abundant in most nNOS-negative neurons. In addition, nNOS-ir neurons exhibit selective staining for the alternative C2' terminus of NMDAR1 that is produced when the C2 segment is absent. These results demonstrate directly that neurons with abundant nNOS-ir contain NMDAR1 receptor subunit proteins and that the NMDAR1 isoforms present in these cells differ from those of most other neurons in these regions. The distinct NMDA receptor phenotype of these nNOS-positive neurons is likely to contribute to both the physiological regulation of NO release by glutamate as well as to NO-mediated excitotoxic injury.
一氧化氮（NO）是一种非传统的可扩散神经递质，由一氧化氮合酶（NOS）合成。N-甲基-D-天冬氨酸（NMDA）谷氨酸受体是NO合成的有效调节因子。我们使用双标记免疫荧光和共聚焦显微镜检查大鼠前脑神经元，以检测含有高水平神经元型NOS（nNOS）的神经元中是否存在NMDAR1受体亚基蛋白，以及该蛋白由NMDAR1 mRNA的三个可变剪接片段编码的区域：N1、C1和C2。在新纹状体、新皮质和海马体中，nNOS标记的神经元表现出强烈的NMDAR1免疫反应性（-ir）。在所有这三个区域中，nNOS阳性神经元的特征是对NMDAR1的C1片段无免疫反应性，而在大多数nNOS阴性神经元中C1-ir丰富。此外，nNOS-ir神经元对NMDAR1的替代C2'末端表现出选择性染色，该末端在C2片段缺失时产生。这些结果直接表明，具有丰富nNOS-ir的神经元含有NMDAR1受体亚基蛋白，并且这些细胞中存在的NMDAR1亚型与这些区域中大多数其他神经元的亚型不同。这些nNOS阳性神经元独特的NMDA受体表型可能有助于谷氨酸对NO释放的生理调节以及NO介导的兴奋性毒性损伤。
