神经病理性痛大鼠背根神经节神经元IB4和CGRP表达的变化

摘要

目的 评价神经病理性痛大鼠背根神经节神经元植物凝集素B4(IB4)和降钙素基因相关肽(CGRP)表达的变化.方法 雄性健康SD大鼠40只,体重250～280 g,采用随机数字表法分为2组(n=20):溶媒组(S组)和神经病理性痛组(NP组).NP组腹腔注射树脂毒素210 μg/kg制备神经病理性痛模型,S组腹腔注射树脂毒素溶媒.分别于造模前、造模后1、3、7和42 d时取5只大鼠,测定机械缩足反应阈(MWT)和热缩足潜伏期(TWL).分别于造模后1、3、7和42 d时处死5只大鼠,取L4-6背根神经节组织,采用免疫荧光法测定神经元CGRP和IB4的表达水平.结果 与造模前比较,NP组造模后3、7和42d时MWT降低,造模后1、3、7和42d时TWL延长(P＜0.05).与S组比较,NP组造模后3、7和42 d时MWT降低,造模后各时点TWL延长,背根神经节神经元CGRP和IB4的表达下调(P＜0.05).结论 神经病理性痛大鼠背根神经节神经元IB4表达下调可能参与了机械痛觉超敏的形成和维持,CGRP表达下调可能参与了热痛觉失敏的形成和维持.%Objective To evaluate the changes in the expression of isolectin B4 (IB4) and calcium gene-related peptide (CGRP) in neurons in dorsal root ganglion (DRG) of rats with neuropathic pain (NP).Methods Forty healthy male Sprague-Dawley rats,weighing 250-280 g,were divided into 2 groups (n =20 each) using a random number table method:solvent group (group S) and group NP.NP was induced by intraperitoneally injecting resiniferatoxin 210 μg/kg,and the solvent of resiniferatoxin was intraperitoneally injected in group S.The mechanical paw withdrawal threshold (MWT) and thermal paw withdrawal latency (TWL) were measured in 5 rats selected before establishing the model and at 1,3,7 and 42 days after establishing the model.Five rats were sacrificed at 1,3,7 and 42 days after establishing the model,and the L4-6 segments of the DRGs were removed to determine the expression of CGRP and IB4 in neurons using immunofluorescence.Results Compared with the baseline before establishing the model,the MWT was signilicantly decreased at 3,7 and 42 days after establishing the model,and the TWL was prolonged at 1,3,7 and 42 days after establishing the model in group NP (P＜0.05).Compared with group S,the MWT was significantly decreased at 3,7 and 42 days after establishing the model,the TWL was prolonged at 1,3,7 and 42 days after establishing the model,and the expression of IB4 and CGRP in neurons in DRGs was down-regulated at 1,3,7 and 42 days after establishing the model in group NP (P＜0.05).Conclusion Down-regulated expression of IB4 expression in neurons in DRGs may be involved in the development and maintenance of mechanical hypersensitivity to pain,and down-regulated expression of CGRP may be involved in the development and maintenance of thermal analgesia in rats with NP.