miR-146a激动剂对大鼠神经病理性疼痛行为学和IRAK1、TRAF6表达的影响

EFFECTS OF AGOMIR-146A ON PAIN BEHAVIOR AND EXPRESSION OF IRAK1 AND TRAF6 IN NEUROPATHIC PAIN RATS

目的：探讨miR-146a激动剂（agomiR-146a）经鞘内给药对大鼠神经病理性疼痛的影响.方法：雌性SD大鼠16只,体重200～250g,采用随机数字表法随机分为对照组（n=8）和agomiR-146a组（n=8）,两组均行双侧坐骨神经结扎手术,于手术当天及术后第3、5、7、10天分别经鞘内注射体积为15 μl的agomiR-对照组或agomiR-146a（5nmol溶于生理盐水）,于术前及术后第1、3、7、14天进行动物行为学评估,观察大鼠对机械和热刺激的反应.实时定量PCR法检测术后第14天大鼠L4～6背根神经节（dorsal root ganglion,DRG）中miR-146a、白介素1受体相关激酶（interleukin-1receptor-associated kinase 1,IRAK1）、肿瘤坏死因子受体相关因子6（tumor necrosis factor-associated factor 6,TRAF6）的mRNA表达水平;Western-blot法检测IRAK1及TRAF6蛋白表达水平变化.结果：agomiR-146a组大鼠缩足反射热辐射潜伏期自建模后3天显著增加,而缩足反射机械刺激阈值在建模后7和14天比对照组明显升高（P＜0.05）.与对照组相比,术后14天agomiR-146a组miR-146a表达显著上调（P＜0.05）,IRAK1、TRAF6的mRNA表达水平下降（P＜0.05）;agomiR-146a组IRAK1、TRAF6蛋白水平亦明显降低（P＜0.05）.结论：miR-146a激动剂agomiR-146a经鞘内给药可以减轻大鼠神经病理性疼痛,可能为治疗神经病理性疼痛提供新的靶点.

Objective： To investigate the effects of intrathecal injection of agomiR-146a on neuropathic pain in rats. Methods： Sixteen female SD rats weighing 200-250 g were randomly divided into agomiR-control group （n = 8） and agomiR-146a group （n = 8）. Rats in both groups received bilateral chronic sciatic nerve constriction injury （bCCI）. AgomiR-146a or equal volume of saline was administered intrathecally on the surgery day and on day 3, 5, 7 and 10 after surgery. The paw withdrawal mechanical threshold （PWMT） and paw withdrawal thermal latency （PWTL） were used to evaluate and measure the behavioral changes before operation, on dayl, 3, 7 and 14 after surgery. L4-6 dorsal root ganglions were harvested on dayl4 after surgery. RT-qPCR was used to test the mRNA expression of miR-146a, interleukin-1 receptor-associated kinase 1 （IRAK1） and tumor necrosis factor-associated factor 6 （TRAF6）. Western Blot was performed to explore the protein expression of IRAK1 and TRAF6. Results： Compared with control group, an increase of PWTL was observed from day 3 after surgery whereas PWMT increased only on day 7 and 14 after surgery in the agomiR- 146a group （P 〈 0.05）; The expression ofmiRNA-146a in DRG was greatly increased, however, the mRNA expression of IRAK1 and TRAF6 in DRG were significantly decreased on day 14 after surgery in the agomiR-146a group （P 〈 0.05）. Western Blot result showed that IRAK1 and TRAF6 protein level decreased in DRG of bCCI rats in the agomiR-146a group on day 14 postoperatively （P 〈 0.05）. Conclusions： Intrathecal injection of agomiR-146a can alleviate the behavior of bCCI rats. Therefore, agomiR-146a may be a novel target for neuropathic pain.