慢性背根神经节压迫诱导神经病理性痛大鼠脊髓背角NMDA受体磷酸化的变化

Changes in phosphorylation of NMDA receptors in spinal dorsal horns in a rat model of neuropathic pain induced by chronic compression of dorsal root ganglion

目的 探讨慢性背根神经节压迫（CCD）诱导神经病理性痛大鼠脊髓背角NMDA受体磷酸化的变化.方法 健康雄性成年SD大鼠96只,体重200 ～ 250 g,采用随机数字表法,将其分为3组（n=32）：正常对照组（C组）、假手术组（S组）和CCD组.CCD组于脊髓L4,5椎间孔插入4#钢针制备CCD诱导神经病理性痛大鼠模型.分别于术前1d、术后1、2和4周时测定热缩足反应潜伏期（PWL）,测定PWL后处死,取脊髓腰膨大部位,分别采用免疫组化法和Western blot法检测损伤侧脊髓背角IL-1β和NMDA受体NR1亚基的丝氨酸896位点磷酸化蛋白（pNR1S896）的表达水平.结果 与C组比较,CCD组术后各时点PWL缩短,脊髓背角IL-1β和pNR1S896的表达上调（P＜0.05）;S组术后1周时PWL缩短,脊髓背角IL-1β和pNR1S896的表达上调（P＜0.05）,其余各时点PWL、脊髓背角IL-1β和pNR1S896的表达差异无统计学意义（P＞0.05）.与S组比较,CCD组术后各时点PWL缩短,脊髓背角IL-1β和pNR1S896的表达上调（P＜0.05）.与术前1d时比较,CCD组PWL术后1周开始缩短,术后2周降至最低并持续到术后4周,脊髓背角IL-1β和pNR1S896的表达于术后1周开始上调,术后2周升至最高并持续到术后4周（P＜0.05）;S组术后1周时PWL缩短,脊髓背角IL-1β和pNR1S896的表达上调（P＜0.05）.结论 CCD诱导大鼠神经病理性痛的形成与维持与脊髓背角NMDA受体NR1亚基磷酸化有关.

Objective To investigate the changes in the phosphorylation of N-methyl-D-aspartate （NMDA） receptors in spinal dorsal horns in a rat model of neuropathic pain induced by chronic compression of dorsal root ganglion （CCD）.Methods Ninety-six male Sprague-Dawley rats,weighing 200-250 g,were randomly divided into 3 groups （n =32 each） using a random number table：control group （group C）,sham operation group （group S） and group CCD.In CCD group,a small stainless steel needle （4 mm in length and 0.8 mm in diameter） was inserted into the L4,5 intervertebral foramen in pentobarbital sodium-anesthetized rats,developing intervertebral foramen stenosis and hence producing a chronic steady compression of the dorsal root ganglion.In group S,the intervertebral foramen was only exposed without inserting the needle.The paw withdrawal latency （PWL） was measured at 1 day before operation and 1,2 and 4 weeks after operation.The rats were then sacrificed after measurement of PWL and the lumbar enlargement segments of the spinal cord were removed for determination of the expression of interleukin-1β （IL-1β） and phosphorylation of NMDA receptor NR1 subunits at serine 896 （pNR1S896） on the injured side by immunohistochemistry and Western blot.Results Compared with group C,the PWL was significantly shortened at each time point after operation,and the expression of IL-1β and pNR1S896 was up-regulated in group CCD,and the PWL was shortened at 1 week after operation,the expression of IL-1β and pNR1S896 was up-regulated,and no significant change was found in PWL and expression of IL-1β and pNR1S896 at the other time points in group S.Compared with group S,the PWL was significantly shortened at each time point after operation,and the expression of IL-1β and pNR1S896 was up-regulated in group CCD,Compared with the baseline value at 1 day before operation,the PWL was slowly shortened starting from 1 week after operation,and decreased to the lowest level at 2 weeks after operation and maintained at this level for 2 weeks,the expression of IL-1β and pNR1S896 was slowly up-regulated starting from 1 week after operation,and increased to the highest level at 2 weeks after operation and maintained at this level for 2 weeks in group CCD,and the PWL was shortened at 1 week after operation,and the expression of IL-1β and pNR1 S896 was up-regulated in group S.Conclusion The development and maintenance of neuropathic pain induced by CCD are related to phosphorylation of NMDA receptors in spinal dorsal horns of rats.