鞘内注射Salubrinal对大鼠神经病理性痛的影响

Effects of intrathecal salubrinal on neuropathic pain in rats

目的评价鞘内注射特异性真核翻译起始因子2α(eIF2α)去磷酸化抑制剂(Salubrinal)对大鼠神经病理性痛的影响。方法SPF级健康雄性SD大鼠45只,8~10周龄,体重220~280 g。采用随机数字表法分为5组(n=9):假手术组(Sham组)、神经病理性痛组(NP组)和不同剂量Salubrinal组(S1组、S2组、S3组)。采用坐骨神经慢性缩窄损伤(CCI)法制备神经病理性痛模型。于CCI术后第4天行为学测试结束后鞘内注射37.5μmol Salubrinal 10μl(S1组)、15μl(S2组)、20μl(S3组),Sham组和NP注射5%DMSO+生理盐水20μl,连续给药10 d,1次/d。于CCI术前1 d、术后1、3、5、7、10和14 d(鞘内给药后1 h)时测定术侧足机械缩足反应阈(MWT)和热缩足潜伏期(TWL)。于CCI术后第14天行为学测试结束后,处死大鼠,取背根神经节组织,采用Western blot法检测BIP、eIF2α、p-eIF2α表达水平,免疫荧光法检测BIP、p-eIF2α表达水平,HE染色观察神经元形态变化。结果与Sham组比较,NP组CCI术后各时点MWT降低,TWL缩短,BIP和p-eIF2α表达上调,p-eIF2α/eIF2α比值升高(P<0.05)。与NP组比较,S1组p-eIF2α表达下调,p-eIF2α/eIF2α比值降低(P<0.05),各时点MWT和TWL差异无统计学意义(P>0.05),S2组和S3组CCI术后5~14 d MWT升高,TWL延长,BIP和p-eIF2α表达下调,p-eIF2α/eIF2α比值降低(P<0.05),DRG神经元形态结构损伤均有不同程度的改善。结论鞘内注射Salubrinal可能通过抑制背根神经节神经元内质网应激,减轻大鼠神经病理性痛。

Objective To evaluate the effects of intrathecal salubrinal a synthetic compound that inhibits de-phosphorylation of eukaryotic translation initiation factor 2 alpha(eIF2α)on neuropathic pain(NP)in rats.Methods Forty-five adult male Sprague-Dawley rats,aged 8-10 weeks,weighing 220-280 g,were divided into 5 groups(n=9 each)using a random number table mehtod:sham operation group(group Sham),group NP,and different doses of salubrinal groups(S1,S2 and S3 groups).NP was induced by chronic constrictive injury(CCI)to sciatic nerve in anesthetized rats.After behavioral testing on 4th day after establishing the NP model,37.5μmol salubrinal 10μl(group S1),15μl(group S2)and 20μl(group S3)were intrathecally injected,and 5%DMSO+normal saline 20μl was injected once a day for 10 consecutive days in Sham and NP groups.The mechanical paw withdrawal threshold(MWT)and thermal paw withdrawal latency(TWL)were measured at 1 day before CCI and 1,3,5,7,10 and 14 days after CCI(1 h after intrathecal administration).The rats were sacrificed after the end of behavioral testing on 14th day after CCI,and the dorsal root ganglion(DRG)of the lumbar segment was removed for determination of the expression of BIP,eIF2αand p-eIF2α(by Western blot)and expression of BIP and p-eIF2α(by immunofluorescence)and for examination of the morphological changes of DRG neurons(by HE staining).Results Compared with group Sham,the MWT was significantly decreased,and TWL was shortened at each time point after CCI,the expression of BIP and p-eIF2αwas up-regulated,and the p-eIF2α/eIF2αratio was increased in group NP(P<0.05).Compared with group NP,the expression of p-eIF2αwas significantly down-regulated,the ratio of p-eIF2α/eIF2αwas decreased(P<0.05),and no significant change was found in MWT and TWL at each time point in group S1(P>0.05),and MWT was significantly increased,and TWL was prolonged at 5-14 days after CCI,the expression of BIP and p-eIF2αwas significantly down-regulated,and the p-eIF2α/eIF2αratio was decreased(P<0.05),and the morphological changes of DRG neurons were significantly improved in different degrees in S2 and S3 groups.Conclusion Intrathecal salubrrinal reduces NP probably by inhibiting endoplasmic reticulum stress in DRG neurons of rats.