姜黄素对利多卡因诱导大鼠神经损伤的影响:Akt和ERK 1∕2信号通路在其中的作用

摘要

目的 评价姜黄素对利多卡因诱发大鼠神经损伤的影响及蛋白激酶B(Akt)和细胞外信号调节激酶1∕2(ERK1∕2)信号通路在其中的作用.方法 SPF级雄性SD大鼠80只,8～10周龄,体重220～250 g,采用随机数字表法分为8组(n=10):对照组(C组)、假手术组(S组)、利多卡因组(L组)、二甲基亚砜(DMSO)组(D组)、姜黄素低剂量组(CL组)、姜黄素高剂量组(CH组)、姜黄素+ERK抑制剂PD98059组(P组)和姜黄素+Akt抑制剂MK-2206组(M组).除C组和S组外,其余6组行鞘内置管,注射2％利多卡因10μl制备利多卡因诱发神经损伤模型.于鞘内置管后第3天开始,连续14 d,采用微导管注射给药:D组、CL组和CH组分别注射DMSO10μl、姜黄素100μg∕10μl及姜黄素500μg∕10μl,1次∕d;P组和M组注射姜黄素500μg∕10μl,1次∕d,分别腹腔注射D9805910μg和MK-220612μg,均溶于5μl DMSO溶液,每周给药1次.于鞘内置管前1 d、鞘内置管后第3天给药前、给药第14天时测定术侧后肢机械缩足反应阈(MWT)和热缩足潜伏期(TWL).给药结束后第1天,取脊髓组织,采用Western blot法检测脊髓ERK1∕2、磷酸化ERK1∕2(p-ERK1∕2)、Akt、磷酸化Akt(p-Akt)、c-fos、Bcl-2、Bax表达水平;采用Real-time PCR法检测脊髓ERK1∕2和Akt的mRNA表达水平.结果 与C组比较,L组MWT降低,TWL缩短,ERK1∕2及其mRNA、p-ERK1∕2、c-fos、Akt及其mRNA、p-Akt、Bcl-2表达下调,Bax表达上调(P<0.05);与L组比较,CL组、CH组、P组和M组MWT升高,TWL延长,CL组和CH组p-ERK1∕2、c-fos、p-Akt、Bcl-2表达上调,Bax表达下调,P组p-Akt、Bcl-2表达上调,Bax表达下调,M组p-ERK1∕2、c-fos表达上调(P<0.05);与CH组比较,P组和M组MWT降低,TWL缩短,P组脊髓p-ERK1∕2、c-fos表达下调,M组脊髓p-Akt和Bcl-2表达下调,Bax表达上调(P<0.05).结论 姜黄素可减轻利多卡因诱发的大鼠神经损伤,部分机制可能与增强Akt和ERK1∕2信号通路活性有关.%Objective To evaluate the effect of curcumin on lidocaine-induced nerve injury and the role of protein kinase B ( Akt) and extracellular signal-regulated kinase 1∕2 ( ERK1∕2) signaling pathway in rats. Methods Eighty SPF male Sprague-Dawley rats, aged 8-10 weeks, weighing 220-250 g, were di-vided into 8 groups ( n=10 each) using a random number table method: control group ( group C) , sham operation group (group S), lidocaine group ( group L), dimethyl sulfoxide ( DMSO) group, low-dose curcumin group ( group CL ) , high-dose curcumin group ( group CH ) , curcumin plus ERK inhibitor PD98059 group (group P) and curcumin plus Akt inhibitor MK-2206 group (group M). The model of nerve injury was established by injecting 2％ lidocaine 10μl via the catheter in anesthetized rats in the other six groups except for C and S groups. Drugs were injected through a microcatheter for 14 consecutive days starting from 3rd day after IT catheterization as follows: DMSO 10μl, curcumin 100μg∕10μl and curcu-min 500 μg∕10 μl were injected once a day in D, CL and CH groups, respectively; curcumin 500 μg∕10μl was injected once a day, and D9805910μg and MK-220612μg ( in 5μl DMSO) were intraperitoneal-ly injected once a week in P and M groups, respectively. The mechanical paw withdrawal threshold ( MWT) and thermal paw withdrawal threshold ( TWL) on the operated side were measured on 1 day before IT catheterization, before administration on 3rd day after IT catheterization, and on 14th day after adminis-tration. The spinal cord was removed on 1st day after the end of administration for determination of the ex-pression of ERK1∕2, phosphorylated ERK1∕2 (p-ERK1∕2), Akt, phosphorylated Akt (p-Akt), c-fos, Bcl-2 and Bax ( by Western blot) and expression of ERK1∕2 and Akt mRNA ( by real-time polymerase chain reaction) . Results Compared with group C, the MWT was significantly decreased, the TWL was short-ened, the expression of ERK1∕2 protein and mRNA, p-ERK1∕2, c-fos, Akt protein and mRNA, p-Akt and Bcl-2 was down-regulated, and the expression of Bax was up-regulated in group L (P<0. 05). Com-pared with group L, the MWT was significantly increased, and the TWL was prolonged in CL, CH, P and M groups, the expression of p-ERK1∕2, c-fos, p-Akt and Bcl-2 was up-regulated, and the expression of Bax was down-regulated in CL and CH groups, the expression of p-Akt and Bcl-2 was up-regulated, and the expression of Bax was down-regulated in group P , and the the expression of p-ERK1∕2 and c-fos was up-regulated in group M ( P<0. 05) . Compared with group CH, the MWT was significantly decreased, and the TWL was shortened in P and M groups, the expression of p-ERK1∕2 and c-fos was down-regulated in group P, and the expression of p-Akt and Bcl-2 was down-regulated, and the expression of Bax was up-reg-ulated in group M ( P<0. 05) . Conclusion Curcumin can reduce lidocaine-induced nerve injury, and the mechanism may be partly related to enhancing the activity of Akt and ERK1∕2 signaling pathway in rats.