阿霉素减轻坐骨神经慢性缩窄性损伤大鼠的神经病理性疼痛及其机制

摘要

目的 观察阿霉素(DOX)对坐骨神经慢性缩窄性损伤(CCI)模型大鼠的镇痛作用,并从形态学及组织凋亡蛋白的角度对其机制进行分析.方法 将SD大鼠随机分为4组:假手术组(Sham)、CCI模型组(Model)、假手术+阿霉素5 mg·kg-1组(Sham+DOX)、CCI模型+阿霉素5 mg·kg-1组(Model+DOX).造模成功后,各组采用尾静脉注射的方式给药,Sham组和Model组给予等量生理盐水,检测各组大鼠机械痛阈值和热痛阈值.在行为学检测结束后,即手术后d 15取大鼠右侧L4-5 DRG,观察DRG细胞形态、超微结构及DOX的分布情况,采用Western blot法测定DRG组织中Bax、Bcl-2、PKCɑ、PKCδ及PKCε的蛋白表达.结果 静脉注射DOX可在DRG组织检测到其自发荧光表达.与Sham组相比,Sham+DOX组痛阈值在整个观察期未见差别,而Model组在术后d 7痛阈值明显降低.与Model组相比,Model+DOX组的痛阈值在给药后明显回升,并表现出DRG细胞明显损伤,Bax/Bcl-2升高以及PKCδ、PKCε的蛋白表达量降低等现象.结论 DOX静脉注射可以到达并蓄积于DRG组织,明显减轻CCI大鼠的疼痛反应,这一作用与其降低PKCδ和PKCε的蛋白表达,诱导DRG的凋亡有关.%Aim To observe the analgesic effect of doxorubicin ( DOX) on chronic sciatic nerve constric-tion injury (CCI) rat model, and analyze the underly-ing mechanism from the ultrastructure of sciatic nerve ganglion and the expressions of some apoptotic pro-teins.Methods A total of 60 SD rats were randomly divided into four groups: sham operation group ( Sham ) , CCI model group ( Model ) , sham operation+DOX 5 mg· kg -1 group ( Sham+DOX) , CCI mod-el +DOX 5 mg· kg -1 group (Model+DOX).DOX was given by caudal vein injection after model estab-lishment .Sham group and model group were given the same amount of saline . The mechanical withdrawal threshold and thermal withdrawal latency were deter-mined by behavioral test .The ultrastructural changes of L4-5 DRG were examined by light microscopy and scanning electron microscopy , respectively .The pro-tein expression levels of Bax , Bcl-2 , PKCɑ, PKCδand PKCε in DRG tissues were determined by Western blot.Results The fluorescence of DOX was found in DRG after DOX was given intravenously .In compari-son with sham group , the thermal and mechanical pain thresholds had no obvious changes in sham +DOX group, while the thresholds were decreased obviously seven days after surgery in model group .In comparison with model group , the pain thresholds in model +DOX group increased significantly , which lasted for the en-tire observation time of six days .The ultra-structure of tissues was damaged obviously in both sham +DOX group and model+DOX group.The protein expression of Bax/Bcl-2 increased, while the expressions of PKCδand PKCεdecreased with DOX injection .Conclusions DOX can retrograde and reach the DRG tissues after intravenous administration . The attenuation effect of DOX on neuropathic pain is related to the apoptosis in-duced by the down-regulation of PKCδ and PKCε in DRG cells.