脊髓小胶质细胞活化在大鼠术后持续性痛中的作用

目的 探讨脊髓小胶质细胞活化在大鼠术后持续性痛中的作用.方法选择鞘内置管成功的雄性SD大鼠72只,体重200～250 g,采用随机数字表法,将其随机分为3组(n=24):假手术组、皮肤肌肉切口牵拉组(SMIR组)和米诺环素组.采用皮肤肌肉切口牵拉法建立大鼠术后持续性痛模型,假手术组和SMIR组于术前30 min和术后1～3 d鞘内注射人工脑脊液20 μl,1次,d;米诺环素组于术前30 min和术后1～3 d鞘内注射米诺环素10 μl,1次/d,并在每次注药后经导管注射人工脑脊液10 μl冲洗导管.于术前1 d及术后3、7、12、22和32 d时测定机械缩足反射阈值(MWT),各时点MWT测定结束后,随机取4只大鼠,测定脊髓背角小胶质细胞特异性标记物Iba-1的表达和计数小胶质细胞.结果 与假手术组比较,SMIR组和米诺环素组术后3～22 d时MWT降低,术后3、7 d时脊髓背角Iba-1表达和小胶质细胞计数升高(P＜0.05);与SMIR组比较,米诺环素组术后3～22 d时MWT升高,术后3、7 d时脊髓背角Iba-1表达和小胶质细胞计数降低(P＜0.05).结论 脊髓小胶质细胞的活化参与了大鼠术后持续性痛的形成.

Abstract：

Objective To investigate the role of microglial activation in spinal cord in a rat model of persistent postoperative pain evoked by skin/muscle incision and retraction (SMIR) .Methods Seventy-two male SD rats weighing 200-250 g in which intrathecal (IT) catheter was successfully inserted were randomly divided into 3 groups ( n = 24 each) : group sham operation; group SMIR and group SMIR + FT minocycline (a specific microglia inhibitor) . The rat model of persistent postoperative pain evoked by SMIR was established according to the method described by Flatters. Pain behavior was assessed by paw mechanical withdrawal threshold ( MWT) to von Frey filament stimulation at 1 day before (T0,baseline) and 3, 7, 12, 22 and 32 days after operation (T1-5,) . Four animals were sacrificed at each time point in each group for detection of the expression of Iba-1 (a specific marker of microglia) in the spinal dorsal horn by immunofluorescence and the microglia was counted. Results MWT was significantly decreasedat T1-4, while the expression of Iba-1 and microglia counts in the spinal dorsal horn were significantly increased at T1, 2 by SMIR in group Ⅱ. IT minocycline significantly attenuated the hyperalgesia induced by SMIR at T1-4 and decreased Iba-1 expression and microglia counts at T1,2 in group Ⅲ. Conclusion Microglial activation in the spinal cord plays an important role in the development and maintenance of SMIR-evoked persistent postoperative pain in rats.

The role of microglial activation in spinal cord in a rat model of persistent postoperative pain evoked by skin/muscle incision and retraction

Objective To investigate the role of microglial activation in spinal cord in a rat model of persistent postoperative pain evoked by skin/muscle incision and retraction (SMIR) .Methods Seventy-two male SD rats weighing 200-250 g in which intrathecal (IT) catheter was successfully inserted were randomly divided into 3 groups ( n = 24 each) : group sham operation; group SMIR and group SMIR + FT minocycline (a specific microglia inhibitor) . The rat model of persistent postoperative pain evoked by SMIR was established according to the method described by Flatters. Pain behavior was assessed by paw mechanical withdrawal threshold ( MWT) to von Frey filament stimulation at 1 day before (T0,baseline) and 3, 7, 12, 22 and 32 days after operation (T1-5,) . Four animals were sacrificed at each time point in each group for detection of the expression of Iba-1 (a specific marker of microglia) in the spinal dorsal horn by immunofluorescence and the microglia was counted. Results MWT was significantly decreasedat T1-4, while the expression of Iba-1 and microglia counts in the spinal dorsal horn were significantly increased at T1, 2 by SMIR in group Ⅱ. IT minocycline significantly attenuated the hyperalgesia induced by SMIR at T1-4 and decreased Iba-1 expression and microglia counts at T1,2 in group Ⅲ. Conclusion Microglial activation in the spinal cord plays an important role in the development and maintenance of SMIR-evoked persistent postoperative pain in rats.