脊髓小胶质细胞在糖尿病神经痛形成中的作用

Role of Spinal Cord Microglia in the Pathogenesis of Diabetic Neuropathic Pain in Rats

目的:观察大鼠糖尿病神经痛模型中脊髓小胶质细胞的活化状态和P物质含量的变化及腹腔注射米诺环素后的效应。方法:48只Wistar雄性大鼠,12只为正常对照组(C组);其余单次腹腔注射STZ制备糖尿病模型。自注射STZ前1 d起,连续29 d,糖尿病大鼠注入米诺环素40 mg/kg(M4组)、20 mg/kg(M2组)、等量PBS(D组)。在注射STZ前1 d、注射STZ后7 d、14 d、21 d、28 d(t1～5)测定机械性缩足反射阈值MWT。在t5时处死大鼠取脊髓,免疫组化测定P物质含量,RT-PCR测定小胶质细胞标志性蛋白CR3表达。结果:与C组相比,D组MWT下降,P物质含量降低,CR3 mRNA表达增强(P<0.05);与D组相比,M4组MWT升高,M4组和M2组P物质含量升高,CR3 mRNA表达减弱(P<0.05);与M2组相比,M4组MWT和P物质含量均升高(P<0.05),CR3 mRNA表达差异无统计学意义(P>0.05)。结论:糖尿病神经痛的形成依赖于脊髓内激活的小胶质细胞,P物质在该模型中含量减少,小胶质细胞活化被米诺环素抑制的同时,P物质含量增加并且神经痛得到了改善。

Objective To investigate the activation of spinal cord microglia,the content change of substance P and the effect of minocycline in rats with diabetic neuropathic pain.Methods Thirty-six Wistar male rats were prepared for diabetic neuropathic pain model by STZ intraperitoneal injection,another 12 rats were selected as control group(group C).The model rats were respectively given minocycline at a dose of 40 mg/kg(group M4),20 mg/kg(group M2),0 mg/kg(equal volume of PBS,group D) for 29 d before STZ injection.The paw withdrawal mechanical threshold(MWT) were determined at the following time points:the day before STZ injection,and the 7 d,14 d,21 d,28 d after injection(t1～5).The rats were sacrificed and the spinal cord were taken at t5.The content of substance P in spinal cord was deteced by immuno-histochemical assay,the expression of microglia marker protein CR3 was detected by RT-PCR.Results Compared with group C,the value of MWT and content of substance P were decreased,but the expression of CR3 mRNA was increased in group D(P0.05).Conclusion The pathogenesis of diabetic neuropathic pain may correlate with the activation of spinal cord microglia,the content of substance P was decreased in rats model.Minocycline could inhibit the activation of spinal cord microglia,meanwhile the content of substance P was increased and the neuropathic pain was improved.