脊髓COX-1和COX-2在瑞芬太尼诱发切口痛小鼠痛觉过敏形成中的作用

Role of spinal COX-1 and COX-2 in remifentanil-induced hyperalgesia in mice with incisional pain

目的评价脊髓COX-1和COX-2在瑞芬太尼诱发切口痛小鼠痛觉过敏形成中的作用。方法取雄性C57BL/6J小鼠32只,8~10周龄,体重20~25 g,采用随机数字表法分为4组(n=8):对照组(C组)、切口痛+瑞芬太尼组(IR组)、切口痛+瑞芬太尼+选择性COX-1抑制剂组(IR+SC560组)、切口痛+瑞芬太尼+选择性COX-2抑制剂组(IR+SC236组)。IR组、IR+SC560组和IR+SC236组分别鞘内注射生理盐水10μl、SC56025μg和SC23625μg,15 min后尾静脉注射瑞芬太尼10μg/kg,注射4次,间隔15 min。第1次注射瑞芬太尼后15 min建立切口痛模型。于注射瑞芬太尼或生理盐水前24 h、最后一次注射后3、6、24、48 h(T0-T4)时,测定机械缩足反应阈(MWT)。最后一次痛阈测定结束后处死小鼠,取脊髓组织,采用Western blot法测定脊髓COX-1和COX-2表达水平,采用qRT-PCR法测定脊髓COX-1和COX-2的mRNA表达水平。结果与C组比较,IR组、IR+SC560组和IR+SC236组MWT降低,COX-2及其mRNA表达上调(P<0.05)。与IR组比较,IR+SC560组和IR+SC236组MWT升高(P<0.05)。IR+SC560组与IR+SC236组MWT比较差异无统计学意义(P>0.05)。IR组、IR+SC560组和IR+SC236组COX-2及其mRNA表达水平比较差异无统计学意义(P>0.05)。4组COX-1及其mRNA表达水平比较差异无统计学意义(P>0.05)。结论相比COX-1,脊髓COX-2在瑞芬太尼诱发切口痛小鼠痛觉过敏形成的病理生理机制中发挥主要作用。

Objective To evaluate the role of spinal COX-1 and COX-2 in remifentanil-induced hyperalgesia in mice with incisional pain.Methods Thirty-two male C57BL/6J mice,aged 8-10 weeks,weighing 20-25 g,were divided into 4 groups(n=8 each)using a random number table method:control group(group C),incisional pain plus remifentanil group(group IR),incisional pain plus remifentanil plus selective COX-1 inhibitor group(group IR+SC560),and incisional pain plus remifentanil plus selective COX-2 inhibitor group(group IR+SC236).In IR,IR+SC560 and IR+SC236 groups,normal saline 10μl,SC56025μg and SC23625μg were intrathecally injected,respectively,15 min later remifentanil 10μg/kg was injected via the tail vein for 4 times at 15 min intervals.An incisional pain model was established after the first injection of remifentanil.The mechanical paw withdrawal threshold(MWT)was measured at 24 h before normal saline or remifentanil injection and 3,6,24 and 48 h after the last injection(T0-T4).The mice were sacrificed after the last measurement of pain threshold,and the L4-6 segments of the spinal cord were removed for determination of the expression of COX-1 and COX-2(by Western blot)and expression of COX-1 and COX-2 mRNA(by quantitative real-time polymerase chain reaction).Results Compared with group C,the MWT was significantly decreased,and the expression of COX-2 protein and mRNA was up-regulated in IR,IR+SC560 and IR+SC236 groups(P<0.05).Compared with group IR,the MWT was significantly increased in IR+SC560 and IR+SC236 groups(P<0.05).There was no significant difference in the MWT at each time point between IR+SC560 and IR+SC236(P>0.05).There was no significant difference in the expression of COX-2 protein and mRNA among group IR,group IR+SC560 and group IR+SC236(P>0.05).There was no significant difference in the expression of COX-1 protein and mRNA among the four groups(P>0.05).Conclusion Compared with COX-1,spinal COX-2 plays a major role in the pathophysiological mechanism of remifentanil-induced hyperalgesia in mice with incisional pain.