轴突损伤对大鼠球海绵体肌脊核内运动神经元NMDA受体亚单位表达的影响

CHANGES OF NMDA RECEPTOR SUBUNITS EXPRESSION IN THE MOTONEURONS OF THE RAT SPINAL NUCLEUS OF BULBOCAVENOUS MUSCLE IN RESPONSE TO PUDENDAL NERVE INJURY

本研究观察了轴突损伤对大鼠球海绵体肌脊核(SNB)内运动神经元离子型谷氨酸受体亚单位NMDAR1、NMDAR2A和NMDAR2B表达的影响。实验用雄性SD大鼠,切断单侧阴部神经,动物分别存活1、3、7、14或21d后,进行免疫组织化学染色及定量分析。结果显示正常大鼠SNB内运动神经元表达NMDAR1、NMDAR2A和NMDAR2B亚单位,其中NMDAR2B染色密度最高,NMDAR1次之,NMDAR2A染色密度最低;轴突损伤导致同侧SNB内运动神经元NMDA受体亚单位表达改变,其中NMDAR1染色密度降低,NMDAR2B染色密度增高,而NMDAR2A保持不变。轴突损伤后第3d受体染色密度变化明显,第7d达高峰,第21d恢复近正常水平。本文结果提示,SNB内运动神经元NMDA受体亚单位对轴突损伤呈现不同的反应,这可能与受损运动神经元的存活与再生有关。

Immunohistochemical technique was employed to examine the changes in immunolabeling of the N-methyl-D-aspartate (NMDA) receptor subunits NMDAR1, NMDAR2A and NMDAR2B within the rat spinal nucleus of bulbocavenous muscle (SNB) 1, 3, 7, 14 or 21 days after a unilateral pudendal nerve transection. The results revealed that SNB motoneurons expressed the NMDA receptor subunits NMDAR1, NMDAR2A and NMDAR2B. Among them, the NMDAR2B expression was greater than others. At 3rd day post-lesion, we observed a decrease in NMDAR1 immunolabeling and a increase in NMDAR2B immunolabeling ipsilateral to the lesion, but no change was detected in NMDAR2A immunolabeling. These changes were marked at 7th day post-lesion. At 21st day post-lesion, NMDAR1 and NMDAR2B immunolabelings were returned to normal level.Our study reveals that each subunit of the NMDA receptor displays a different response to the pudendal nerve lesion and suggests that changes in NMDA receptor subunits may be related to the revival and regeneration of SNB motoneurons.