Czaja Krzysztof, Ritter Robert C, Burns Gilbert A
Programs in Neuroscience and Department of Veterinary, Comparative Anatomy, Pharmacology, and Physiology, College of Veterinary Medicine, Washington State University, Pullman, 99163-6520, USA.
J Comp Neurol. 2006 Jun 20;496(6):877-85. doi: 10.1002/cne.20955.
Most vagal afferent neurons in rat nodose ganglia express mRNA coding for the NR1 subunit of the heteromeric N-methyl-D-aspartate (NMDA) receptor ion channel. NMDA receptor subunit immunoreactivity has been detected on axon terminals of vagal afferents in the dorsal hindbrain, suggesting a role for presynaptic NMDA receptors in viscerosensory function. Although NMDA receptor subunits (NR1, NR2B, NR2C, and NR2D) have been linked to distinct neuronal populations in the brain, the NMDA receptor subunit phenotype of vagal afferent neurons has not been determined. Therefore, we examined NMDA receptor subunit (NR1, NR2B, NR2C, and NR2D) immunoreactivity in vagal afferent neurons. We found that, although the left nodose contained significantly more neurons (7,603), than the right (5,978), the proportions of NMDA subunits expressed in the left and right nodose ganglia were not significantly different. Immunoreactivity for NMDA NR1 subunit was present in 92.3% of all nodose neurons. NR2B immunoreactivity was present in 56.7% of neurons; NR2C-expressing nodose neurons made up 49.4% of the total population; NR2D subunit immunoreactivity was observed in just 13.5% of all nodose neurons. Double labeling revealed that 30.2% of nodose neurons expressed immunoreactivity to both NR2B and NR2C, whereas NR2B and NR2D immunoreactivities were colocalized in 11.5% of nodose neurons. NR2C immunoreactivity colocalized with NR2D in 13.1% of nodose neurons. Our results indicate that most vagal afferent neurons express NMDA receptor ion channels composed of NR1, NR2B, and NR2C subunits and that a minority phenotype that expresses NR2D also expresses NR1, NR2B, and NR2C.
大鼠结状神经节中的大多数迷走神经传入神经元表达编码异聚N-甲基-D-天冬氨酸（NMDA）受体离子通道NR1亚基的信使核糖核酸。在延髓背侧的迷走神经传入神经轴突终末检测到了NMDA受体亚基免疫反应性，这表明突触前NMDA受体在内脏感觉功能中发挥作用。虽然NMDA受体亚基（NR1、NR2B、NR2C和NR2D）与大脑中不同的神经元群体有关联，但迷走神经传入神经元的NMDA受体亚基表型尚未确定。因此，我们检测了迷走神经传入神经元中NMDA受体亚基（NR1、NR2B、NR2C和NR2D）的免疫反应性。我们发现，虽然左侧结状神经节中的神经元（7603个）明显多于右侧（5978个），但左右结状神经节中表达的NMDA亚基比例并无显著差异。92.3%的所有结状神经元存在NMDA NR1亚基免疫反应性。56.7%的神经元存在NR2B免疫反应性；表达NR2C的结状神经元占总数的49.4%；仅13.5%的所有结状神经元观察到NR2D亚基免疫反应性。双重标记显示，30.2%的结状神经元对NR2B和NR2C均表达免疫反应性，而NR2B和NR2D免疫反应性在11.5%的结状神经元中共同定位。NR2C免疫反应性与NR2D在13.1%的结状神经元中共同定位。我们的结果表明，大多数迷走神经传入神经元表达由NR1、NR2B和NR2C亚基组成的NMDA受体离子通道，并且表达NR2D的少数表型也表达NR1、NR2B和NR2C。
