脊髓Toll样受体4在胶质细胞活化介导的大鼠持续性术后疼痛中的作用

Role of spinal Toll-like receptor 4 in glial cell activation mediated persistent postoperative pain in a rat model of persistent postoperative pain evoked by skin/muscle incision and retraction

目的 研究脊髓Toll样受体4（toll-like receptor 4,TLR4）在胶质细胞活化介导的大鼠持续性术后疼痛中的作用. 方法 雄性SD大鼠120只,体重200 g～250 g,采用随机数字表法随机分为5组（每组24只）：假手术组（S组）、持续性术后疼痛组[皮肤/肌肉切开和牵拉（skin/muscle incision and retraction,SMIR）组]、SMIR＋鞘内氟代柠檬酸组（F组）、SMIR＋鞘内米诺环素组（M组）和SMIR＋鞘内氟代柠檬酸联合米诺环素组（F＋M组）.按Flatters法制作大鼠SMIR持续性术后疼痛模型;于术前1d及术后3、7、14、21d和32 d时应用yon Frey纤维丝测定机械缩足反射阈值（mechanical withdrawal threshold,MWT）评定大鼠疼痛行为学变化;应用western blot法检测脊髓TLR4蛋白表达的变化. 结果 与术前基础值和S组比较,SMIR组在术后3、7、14、21 d MWT明显降低[分别为（7.3±0.7）、（6.2±1.0）、（4.5±1.2）、（11.4±1.1）g]（P＜0.01）,脊髓TLR4蛋白表达明显增加[分别为（1.647±0.042）、（1.804±0.058）、（2.023±0.161）、（1.365±0.130）]（P＜0.05或P＜0.01）;与SMIR组比较,F组、M组和F＋M组在术后3、7、14、21 d MWT明显升高[术后14 d MWT分别为（7.9±0.7）、（8.4±0.7）、（11.9±1.0） g]（P＜0.05或P＜0.01）,F组在术后7、14 d,M组和F＋M组在术后3、7、14d脊髓TLR4蛋白表达明显减少[术后14dF组、M组、F＋M组TLR4蛋白表达分别为（1.437±0.092）、（1.432±0.129）、（1.047±0.026）]（P＜0.05或P＜0.01）;与F组和M组比较,F＋M组在术后3、7、14 d MWT明显升高[分别为（11.3±0.8）、（10.9±0.6）、（11.9±1.0）g]（P＜0.05）,脊髓TLR4蛋白表达在14 d（1.047±0.026）明显减少（P＜0.05）;F组和M组的MWT和脊髓TLR4蛋白表达差异均无统计学意义. 结论 脊髓TLR4活化与胶质细胞介导的大鼠SMIR持续性术后疼痛的形成有关.

Objective To investigate the role of Toll-like receptor 4 （TLR4） in glial cell activation mediated persistent postoperative pain in a rat model of persistent postoperative pain evoked by skin/muscle incision and retraction （SMIR）.Methods One hundred twenty male SD rats weighting 200 g-250 g,were randomly divided into 5 groups （n=24）：sham operation group（group S）,persistent postoperative pain group （group SMIR）,group SMIR＋intrathecal fiuorocitrate （group F）,group SMIR＋intrathecal minocycline （group M） and group SMIR＋intrathecal minocycline plus fluorocitrate （group F＋M）.The rat model of persistent postoperative pain evoked by SMIR was made according to the method described by Flatters.Pain behavior was assessed by paw mechanical withdrawal threshold （MWT） to yon Frey filament stimulation at 1 d before and 3,7,14,21,32 d after operation.The expression of TLR4 protein in the spinal cord was assessed by western blot analysis.Results Compared with their preoperative values and corresponding values in group S,the MWT values in SMIR were significantly decreased[the MWT values were （7.3±0.7）,（6.2±1.0）,（4.5±1.2）,（11.4±1.1） g] （P〈0.01）,and the expression of TLR4 protein in the spinal cord were significantly increased in group SMIR at 3,7,14 d and 21 d after operation [the expression of TLR4 protein were （1.647±0.042）,（1.804±0.058）,（2.023±0.161）,（1.365±0.130）]（P〈0.05 or P〈0.01）.Compared with corresponding values in group SMIR,the MWT values in group F,group M and group F＋M were significantly increased at 3,7,14 d and 21 d after operation [the MWT values of postoperative 14 d were （7.9±0.7）,（8.4±0.7）,（11.9±1.0） g]（P〈0.05 or P〈0.01）,the expression of TLR4 protein in spinal cord in group F at 7,14 d after operation,and group M and group F＋M at 3,7,14 d after operation significantly decreased [the expression of TLR4 protein of postoperative 14 d in group F,group M,group F＋M were （1.437±0.092）,（1.432±0.129）,（1.047±0.026）,respectively]（P〈0.05 or P〈0.01）.Compared with corresponding values in group F and group M,the MWT values in group F＋M were significantly increased at 3,7 d and 14 d [the MWT values were （11.3±0.8）,（10.9±0.6）,（11.9±1.0） g]（P〈0.05） （P〈0.05）,and the expression of TLR4 protein in spinal cord decreased significantly at 14 d after operation （the expression of TLR4 protein was 1.047±0.026）（P〈0.05）,the MWT values and the expression of TLR4 protein in spinal cord had no significant differences between group F and group M.Conclusions The activation of TLR4 in spinal cord may be related to the glial cell activation mediated persistent postoperative pain in a rat model of persistent postoperative pain evoked by SMIR.