摘要:
目的 通过鞘内注射 N-myc 下游调节基因2(NDRG2)干扰腺病毒(AD-Ndrg2-RNAi),研究脊髓背角内 NDRG2在脊神经结扎(SNL)神经病理性痛模型大鼠中的作用.方法 雄性 SD大鼠42只,体重180~230 g,随机分为假手术组(sham 组,n=6)和 SNL组(n=36),sham组仅暴露脊神经不结扎,SNL组行 L5脊神经结扎术.分别测定术前1 d、术后1、3、7、10、14和21 d大鼠术侧足底机械缩足阈值(MWT)和热缩足潜伏期(TWL).SNL 组大鼠各相应时点行为学测试后分别处死,取术侧脊髓腰膨大,检测NDRG2蛋白含量和mRNA表达量.另取48只雄性SD大鼠行鞘内置管后随机分为四组(n=12):sham+生理盐水组(CS 组)、sham+AD-Ndrg2-RNAi 组(CA组)、SNL+生理盐水组(SS组)和 SNL+AD-Ndrg2-RNAi组(SA组);CS、SS两组大鼠术后3 d鞘内单次注射生理盐水10 μl,CA、SA两组大鼠相同时点鞘内单次注射10 μl,滴度为2×109PFU/ml的AD-Ndrg2-RNAi.于 SNL术前1 d、术后1、3、7和10 d分别测定大鼠足底 MWT和TWL.术后10 d行为学测试后处死大鼠,取术侧脊髓腰膨大,检测 NDRG2和胶质纤维酸性蛋白(GFAP)蛋白含量,采用实时荧光定量PCR(RT-qPCR)法检测 NDRG2 mRNA 的表达量.结果 与 sham 组比较, SNL组术后1、3、7、10、14、21 d MWT明显降低(P<0.01),术后3、7、10、14、21 d TWL明显缩短(P<0.01).与术前1 d比较,SNL组脊髓背角内 NDRG2的蛋白含量和 mRNA表达量在术后1 d明显降低,术后7、10、14、21 d 明显升高(P<0.05).与 CS 组比较,SS 组和 SA 组术后1、3、7、10 d MWT明显降低,TWL 明显缩短(P<0.05);与 SS 组比较,SA 组术后7、10 d MWT 明显升高, TWL明显延长(P<0.05).与CS组比较,术后10 d CA组脊髓背角内NDRG2的蛋白含量和 mR-NA表达量均明显降低(P<0.05),SS组均明显升高(P<0.05);与 SS组比较,SA 组脊髓背角内NDRG2的蛋白含量和 mRNA表达量均明显降低(P<0.05).与 CS组比较,术后10 d CA、SS、SA组脊髓背角内 GFAP蛋白含量均明显升高(P<0.05).结论 NDRG2蛋白含量升高参与了神经病理性痛的形成,鞘内注射 AD-Ndrg2-RNAi明显抑制大鼠脊神经结扎造成的慢性病理性疼痛,提示星形胶质细胞中的 NDRG2参与慢性病理性疼痛的发生和发展.%Objective To investigate the effect of NDRG2 on neuropathic pain model rats with spinal cord ligation(SNL)in the dorsal horn of the spinal cordby using intrathecal NDRG2 adenovirus (AD-Ndrg2-RNAi).Methods Forty-two male SD rats weighing 180-230 g were randomly divided into sham operation group (n=6)and SNL group (n=3 6).SNL group underwent lumbar spinal dor-sal ligation.The sham operation group only exposed the spinal nerve without ligation.The mechanical withdraw threshold (MWT)and thermal withdrawlantency (TWL)were measured at 1 d before op-eration and at 1,3,7,10,14 and 21 d after operation.After the behavioral testing,the rats in SNL group were sacrificed and the lumber segment of the spinal cord was removed to test theprotein and mRNA level of NDRG2.Another forty-eight male SD rats were randomly divided into 4 groups after intrathecal catheterization (n=12):group sham operation with saline (group CS);group sham oper-ation with adenovirus (group CA);group SNL with saline (group SS);group SNL with adenovirus(group SA).The rats in groups CS and SS were treated with intrathecal injection of normal saline 10 μl on the third day after operation,while groups CA and SA received the single injection titer of 2× 109PFU/ml of AD-Ndrg2-RNAi on the same day.The rat plantar MWT and TWL were measured at 1 d before SNL and at 1,3,7 and 10 d after SNL.The rats were sacrificed after the lastbehavioral test.Lumbar enlargement of the spinal cord was removed to test the level of NDRG2 and GFAP pro-tein.The expression of NDRG2 mRNA was detected by real-time fluorescence quantitative PCR. Results Compared with sham group,the MWT and TWL was significantly decreased and reduced in SNL group 1,3,7,10,14,21 d and 3,7,10,14,21 d after surgery respectively(P<0.01).Com-pared with 1 d before surgery,protein content and mRNA expression of NDRG2 in the spinal dorsal horn of the SNL group were significantly decreased 1 d after surgery,and they were significantly in-creased on the 7,10,14,and 21 d after operation(P<0.01).Compared with group CS,the MWT and TWL were significantly decreased and reduced in group SS and group SA 1,3,7 and 10 d after surgery(P<0.05).MWT and TWL on 7 and 10 d were increased significantly in group SA (P<0.05)compared with group SS.Compared with group CS,protein content and mRNA expression of NDRG2 in the spinal dorsal horn of group CA were significantly decreased,and increased significantly in group SS 10 d after surgery(P<0.05).Compared with group SS,protein content and mRNA ex-pression of NDRG2 in the spinal dorsal horn of group SA were significantly decreased.Compared with group CS,the protein content of GFAP in spinal dorsal horn of group CA,group SS and group SA were increased significantly 10 d after surgery (P<0.05).Conclusion Intrathecal injection of AD-Ndrg2-RNAi significantly inhibits neuropathic pain caused by spinal cord ligation in rats,suggesting that NDRG2 in astrocytes is involved in the development and progression of neuropathic pain.