米诺环素对神经病理性疼痛大鼠脊髓水平OX-42表达的影响

THE EFFECT OF MINOCYCLINE ON SPINAL OX-42 EXPRESSION IN NEUROPATHIC PAIN RATS

目的:观察米诺环素对CCI大鼠脊髓水平OX-42表达的影响,探讨小胶质细胞在神经病理性疼痛中的作用。方法:将70只SD大鼠随机分成5组:I组:对照组(n=10)、Ⅱ组:假手术组(n=15)、Ⅲ组:预给药组(n=15)、IV组:术后给药组(n=15)、V组:生理盐水组(n=15)。用von Frey filaments测定大鼠50%缩足阈值的变化;Ⅲ组、IV组、V组大鼠于模型建立后给予米诺环素或者生理盐水,并于术后7、11、13、14、15天从实验组随机取出3只大鼠取其相应节段的脊髓组织,用免疫组织化学的方法观察其特异性标志物OX-42的染色情况。结果:(1)坐骨神经结扎后7d大鼠出现机械性触痛,至实验结束痛行为稳定并持续存在。(2)V组脊髓背角小胶质细胞在术后7d发生激活,至术后11d小胶质细胞被强烈的激活,之后有减退的趋势;IV组小胶质细胞有明显的激活;Ⅱ组和Ⅲ组亦可见小胶质细胞有轻微的激活。结论:脊髓水平小胶质细胞的激活可能对神经病理性疼痛的产生发挥重要作用;米诺环素预先给药可以缓解神经病理性疼痛。

Objective： To observe the effect of minocycline on spinal microglial OX-42 in CCI rats in order to investigate the effect of microglia on neuropathic pain. Methods ： Seventy Sprague-Dawley rats were randomly divided into 5 groups. Group Ⅰ , normal control group （ n = 10） ; group Ⅱ , sham group （ n = 15 ） ; Group Ⅲ, preemptively treated group （ n = 15 ） ; Group Ⅳ, post-operation treatment group ; Group Ⅴ, normal saline administered group. Animal mechanical allodynia was represented by 50% paw withdrawal threshold（50% PWT） that was assessed with von Frey filaments. In group Ⅲ ,group Ⅳand group Ⅴ,the same dose of minocycline or saline was administered after CCI model establishment. And three rats were randomly chosen at timepoint of day 7, day 11, day 13, day 14, day 15 after surgery to evaluate the activation of microglia, by examining spinal OX-42 with immunohistochemical technique. Result： （ 1 ） The mechanical allodynia appeared on day 7 after surgery, and maintaining throughout the whole experiment. （2） OX-42 immunoreactivity in group Ⅴ was observed at day 7 and reached peak at day 11, then declined afterwards. Significant microglia activation in group Ⅳ and mild microglia activation in group Ⅱ and group Ⅲ were observed. Conclusion： Microglial activation in spinal cord might paly an important role in neuropathic pain, and preemptively administered minocycline could inhibit neuropathic pain.