神经营养因子-3对罗哌卡因致大鼠脊髓神经毒性时Akt表达的影响

Effect of neurotrophin-3 on Akt expression during ropivacaine-induced neurotoxicity to spinal cord of rats

目的 评价神经营养因子-3（NT-3）对罗哌卡因致大鼠脊髓神经毒性时丝氨酸/苏氨酸蛋白激酶（Akt）表达的影响.方法 健康雄性SD大鼠,1～2月龄,体重280～320 g,取L5、6间隙行鞘内置管.取鞘内置管成功的大鼠108只,采用随机数字表法分为3组（n=36）：对照组（C组）、1％罗哌卡因组（R组）和1％罗哌卡因＋ NT-3组（NT组）.C组鞘内注射等容量生理盐水,R组和NT组分别鞘内注射1％罗哌卡因0.12 ml/kg,间隔1.5h给药1次,共8次;NT组同时鞘内注射NT-30.1mg/kg.分别于给药结束后1、3、5、7、14和28 d（T1-6）时,每组处死6只大鼠,取脊髓腰膨大,采用TUNEL法检测神经元凋亡率,采用免疫组化法测定Akt表达水平.结果 与C组比较,R组T1-4时脊髓神经元凋亡率升高,T1-3时脊髓Akt表达上调,NT组T1-3时脊髓神经元凋亡率升高,Akt表达上调（P＜0.05）;与R组比较,NT组T3,4时脊髓神经元凋亡率降低,T2.3时Akt表达下调（P＜0.05）.结论 NT-3减轻罗哌卡因致大鼠脊髓神经毒性的机制可能与下调Akt的表达有关.

Objective To evaluate the effect of neurotrophin-3 （NT-3） on the expression of serine/threonine protein kinase （Akt） during ropivacaine-induced neurotoxicity to the spinal cord of rats.Methods Healthy adult male Sprague-Dawley rats,aged 1-2 months,weighing 280-320 g,were used in the study.A catheter was inserted at L5,6 interspace into the epidural space of rats.A total of 108 rats,in which intrathecal catheters were successfully implanted,were randomly divided into 3 groups （n =36each）：control group （group C）,1% ropivacaine group （group R）,and 1% ropivacaine ＋ NT-3 group （group NT）.The equal volume of normal saline was given in group C,1% ropivacaine 0.12 ml/kg was injected via the intrathecal catheter once every 1.5 h for 8 times in total in R and NT groups.In addition,NT-3 0.1 mg/kg was simultanenously injected via the intrathecal catheter in group NT.On days 1,3,5,7,14 and 28 after the end of administration （T1-6）,6 rats were sacrificed in each group.Their lumbar enlargements were removed for determination of neuronal apoptosis （using TUNEL） and Akt expression （by immuno-histochemistry）.The apoptotic rate was calculated.Results Compared with group C,the apoptotic rate was significantly increased at T1-4,and Akt expression was significantly up-regulated at T1-3 in group R,and the apoptotic rate were significantly increased,and Akt expression was significantly up-regulated at T1-3 in group NT （P〈0.05）.Compared with group R,the apoptotic rate was significantly decreased at T3,4,and Akt expression was significantly down-regulated at T2.3 in group NT （P〈0.05）.Conclusion The mechanism by which NT-3 reduces ropivacaine-induced neurotoxicity to the spinal cord may be related to down-regulation of the expression of Akt in rats.