外周疼痛模型大鼠脊髓背角环氧化酶表达时程的研究

目的 探讨环氧化酶参与疼痛过程的特点,从而为揭示疼痛的中枢机制提供线索.方法 选取雄性Sprague-Dawley大鼠50只,20只大鼠右侧后肢足掌皮下注射生理盐水100μl作为对照组.30只大鼠右侧后肢足掌皮下注射5%(体积分数)福尔马林液100μl作为实验组,注射后2、6 h和1、3、7、14天作为测试时间点,每个时间点随机选取5只大鼠,断头后取大鼠脊髓腰膨大部位1 cm(L4～5)组织并分离出背角部分,以免疫印迹法检测不司时间点环氧化酶1和环氧化酶2蛋白的表达.结果 福尔马林注射后大鼠脊髓环氧化酶1表达在注射后1 d开始增多,达到对照组的(2.44±0.43)倍,持续到14 d表达仍明显增多,达对照组的(3.30±0.39)倍.环氧化酶2的表达仪在注射后2 h表达明显增多,达对照组的(1.87±0.34)倍,注射后6 h即恢复到正常,观察到第14天仍然没有变化.结论 环氧化酶1和2可能都参与疼痛的中枢机制,环氧化酶2在疼痛的早期或发生中起作用,而环氧化酶1可能参与疼痛的维持.

Abstract：

Objective To compare the expression of two cyclooxygenase (COX) isoforms (COX-1 and COX-2) in the spinal cord of rats with inflammatory pain following peripheral formalin injection. Methods Experiments were performed on adult male Sprague-Dawley rats. 100μl of 5% formalin were injected subcutaneously into plantar hind paw of 30 rats to induce pain. The changes of COX-1 and COX-2 expression were evaluated by western blot in 30 rats, respectively at 2 hours, 6 hours, 1 day, 3 days, 7 days and 14 days after injection. The control group rats were injected with 100 μl of 0.9% saline instead of formalin in 20 rats. Results The expression of COX-1 significantly increased at 1day, 3 days, 7 days and 14 days, but the expression of COX-2 only transiently increased at 2 hours. Conclusions COX-1 and COX-2 are increasingly expressed in the spinal cord, furthermore,spinal COX-2 expression is induced early and transiently increased. COX-1 is up-regulated later and remains elevated for long time, which may explain the long-term hyperalgesia evoked by formalin injection.

Expression of two cyclooxygenases in spinal cords of formalin rats

Objective To compare the expression of two cyclooxygenase (COX) isoforms (COX-1 and COX-2) in the spinal cord of rats with inflammatory pain following peripheral formalin injection. Methods Experiments were performed on adult male Sprague-Dawley rats. 100μl of 5% formalin were injected subcutaneously into plantar hind paw of 30 rats to induce pain. The changes of COX-1 and COX-2 expression were evaluated by western blot in 30 rats, respectively at 2 hours, 6 hours, 1 day, 3 days, 7 days and 14 days after injection. The control group rats were injected with 100 μl of 0.9% saline instead of formalin in 20 rats. Results The expression of COX-1 significantly increased at 1day, 3 days, 7 days and 14 days, but the expression of COX-2 only transiently increased at 2 hours. Conclusions COX-1 and COX-2 are increasingly expressed in the spinal cord, furthermore,spinal COX-2 expression is induced early and transiently increased. COX-1 is up-regulated later and remains elevated for long time, which may explain the long-term hyperalgesia evoked by formalin injection.