脊髓MCP/DAF表达在大鼠神经病理性痛形成中的作用

Role of MCP/DAF expression in spinal cord in development of neuropathic pain in rats

目的 评价脊髓MCP/DAF表达在大鼠神经病理性痛形成中的作用.方法 MCP/DAF双基因重组转染SD大鼠24只,体重200 ～ 250 g,按照随机数字表法分为2组（n=12）：转染大鼠假手术组（Rsham组）和转染大鼠坐骨神经慢性压迫损伤组（RCCI组）;健康雄性SD大鼠24只,体重200～250 g,按照随机数字表法分为2组（n=12）：正常大鼠假手术组（Nsham组）和正常大鼠坐骨神经慢性压迫性损伤组（NCCI组）.RCCI组和NCCI组大鼠行右侧坐骨神经四道环形结扎,Rsham组和Nsham组大鼠只暴露右侧坐骨神经,不予环形结扎.分别于术前1d和术后1、3和7d时测定大鼠的热痛阈和机械痛阈.术后7d时测定痛阈后处死大鼠,取k,5脊髓,采用免疫组化法检测0X-42的表达,RTPCR法检测MCP mRNA和DAF mRNA的表达.结果 与Nsham组比较,NCCI组大鼠术后1、3和7d时热痛阈和机械痛阈降低,脊髓OX-42表达上调,MCP mRNA和DAF mRNA表达下调（P＜0.05）,Rsham组和RCCI组大鼠术后上述时点热痛阈、机械痛阈和脊髓OX-42表达差异无统计学意义（P＞0.05）,MCP mRNA和DAF mRNA表达上调（P＜0.05）;与NCCI组比较,RCCI组大鼠术后上述时点热痛阈和机械痛阈升高,脊髓OX-42表达下调,MCP mRNA和DAF mRNA表达上调（p＜0.05）.结论 MCP/DAF表达上调抑制大鼠神经病理性痛的形成,其机制与调节脊髓小胶质细胞活化有关.

Objective To evaluate the role of MCP/DAF expression in the spinal cord in the development of neuropathic pain （NP） induced by chronic constrictive injury （CCI） of the sciatic nerve in rats.Methods Twenty-four Sprague-Dawley rats transfected with MCP/DAF,weighing 200-250 g,were randomly divided into 2 groups （n =12 each） using a random number table：sham operation of transfected rat group （Rsham group） and CCI of transfected rat group （RCCI group）.Twenty-four healthy male Sprague-Dawley rats,weighing 200-250 g,were randomly divided into 2 groups （n =12 each） using a random number table：sham operation of normal rat group （Nsham group） and CCI of normal rat group （NCCI group）.The right sciatic nerve was exposed and 4 loose ligatures wen placed on the sciatic nerve at 1 mm intervals with 4-0 catgut in RCCI and NCCI groups.The right sciatic nerve was only exposed in Rsham and Nsham groups.Paw withdrawal threshold to yon Frey filament stimulation （PWT） and paw withdrawal latency to nociceptive thermal stimulation （PWL） were measured at 1 day before operation （baseline） and 1,3 and 7 days after operation.The animals were sacrificed after measurement of pain threshold on 7 days after operation and the L4,5 segment of the spinal cord was removed for determination of the expression of OX-42 （by immuno-histochemistry） and MCP mRNA and DAF mRNA （by RT-PCR）.Results Compared with Nsham group,the PWT and PWL were significantly decreased on 1,3 and 7 days after operation,the expression of OX-42 was up-regulated,and the expression of MCP mRNA and DAF mRNA was down-regulated in NCCI group （P ＜ 0.05）,and no significant changes were found in the PWT and PWL on 1,3 and 7 days after operation and expression of OX-42（P ＞ 0.05）,and the expression of MCP mRNA and DAF mRNA was up-regulated in Rsham and RCCI groups （P ＞ 0.05）.Compared with NCCI group,the PWT and PWL were significantly increased on 1,3 and 7 days after operation,the expression of OX-42 was down-regulated,and the expression of MCP mRNA and DAF mRNA was up-regulated in RCCI group （P ＜ 0.05）.Conclusion Up-regulation of MCP/ DAF expression in the spinal cord can inhibit the development of NP in rats and regulation of activation of microglias in the spinal cord is involved in the mechanism.