吗啡联合加巴喷丁对持续性术后痛大鼠脊髓Toll样受体4表达的影响

Effects of intrathecal coadministration of morphine and gabapentin on the expression of tollAike receptor 4 in spinal cord in persistent postoperative pain rats

目的研究鞘内注射吗啡联合加巴喷丁（gabapentin，GBP）对持续性术后痛大鼠脊髓Toll样受体4（toll-likereceptor4，TLR4）表达的影响。方法选择鞘内置管成功的雄性sD大鼠100只，体重200g-250g，采用随机数字表法随机分为5组（每组20只）：假手术组（S组）、持续性术后痛组[皮肤／肌肉切口和牵拉（skin／muscle incision and retraction，SMIR）组]、SMIR组十鞘内吗啡组（M组）、SMIR组＋鞘内GBP组（G组）和SMIR组＋鞘内吗啡联合GBP组（M±G组）。S组和SMIR组于术前30min和术后1d-3d鞘内注射人工脑脊液（artificial cerebrospinal fluid, ACSF）20μl，1次／d；M组、G组和M组＋G组于术前30min和术后1d-3d分别鞘内注射吗啡2．5μg、GBP50μg和吗啡2．5μg联合GBP50μg，1次／d；采用Flatters法建立大鼠SMIR持续性术后痛模型；于术前1d及术后3、7、12d和22d测定机械缩足反应阈值（mechanical withdrawal threshold，MWT）；采用Western印迹法检测脊髓TLR4蛋白表达的变化。结果与术前及S组比较，SMIR组、M组、G组大鼠术后3、7、12d和22dMWT明显降低[术后12dMWT分别为（54．9±7．7）、（26．1±4．3）、（30．9±4．1）、（31．6±3．8）g]（P〈0．05），术后3、7、12d脊髓TLR4蛋白表达明显增加[术后7dTLR4分别为（22．4±1．1）、（73．9±5．6）、（71．3±3．2）、（70．4±4．5）]（P〈0．05），而SMIR组、M组、G组间比较差异均无统计学意义；与SMIR组、M组和G组比较，M＋G组大鼠术后3、7、12dMWT明显升高[分别为（49±6）、（47±7）、（43．8±2．9）g]（P〈0．05），术后3、7、12d脊髓TLR4蛋白表达则明显较低[分别为（42．6±2．2）、（56．8±3．0）、（38．6±4．8）]（P〈0．05）。结论在SMIR持续性术后痛大鼠中，鞘内吗啡联合GBP的镇痛作用可能与抑制脊髓TLR4表达有关。

Objective To investigate the effects of intrathecal coadministration of morphine and gabapentin （GBP） on the expression of toll-like receptor 4 （TLR4） in spinal cord by using a rat model of persistent postoperative pain evoked by skin/muscle incision and retraction （SMIR）. Methods one hundred male SD rats weighing 200 g-250g were randomly divided into 5 groups （n=20）： sham operation group （group S）, group SMIR, group SMIR ± intratheeal morphine （group M）, group SMIR±intrathecal GBP （group G） and group SMIR±intrathecal morphine and GBP （group M＋G）. The artificial cerebrospinal fluid （ACSF） 20 μl was administered intrathecally at 30 min before operation and 1 d-3 d after operation in group S and group SMIR, respectively. Morphine 2.5 μg, GBP 50 μg and morphine 2.5 μg＋GBP 50μg were administered intrathecally at 30 min before operation and 1 d-3 d after operation in group M, group G and group M±G,respectively. 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 withdraw threshold（MWT） to electronic yon frey anesthesiometer stimulation at 1 d before and 3,7,12,22 d after operation. Four animals were sacrificed at each time point in each group for detection of the expression of TLR4 protein in the spinal cord by Western blot analysis. Results Compared with their preoperative values and corresponding values in group S, the MWT values in group SMIR, group M and group G were significantly decreased at 3, 7, 12 d and 22 d [ the MWT values of postoperative 12 d were （54.9±7.7）, （26.1 ±4.3 ）, （30.9±4.1）, （31.6±3.8） g]（P〈0.05）, and the expression of TLR4 protein in the spinal cord were significantly increased at 3, 7, 12 d after operation [ the expression of TLR4 protein of postoperative 7 d were （22.4 ± 1.1 ）, （73.9 ±5.6 ）, （71.3 ±3.2）, （70.4 ±4.5 ） ] （P〈0.05）, while no significant differences were showed among group SMIR, group M and group G. Compared with group SMIR, M and G, the value of MWT were（49±6）, （47±7）, （43.8±2.9） g significantly increased after 3,7,12 d after operation（P〈0.05）, and the expression of TLR4 protein in the spinal cord were （42.6±2.2）, （56.8±3.0）, （38.6±4.8） significantly decreased at 3,7, 12 d after operation in group M＋G （P〈0.05）. Conchlsions The analgesic effects of intrathecal coadministration of morphine and GBP may be related to the inhibition of spinal TLR4 expression in a rat model of persistent postoperative pain evoked by SMIR.