胍丁胺对糖尿病神经病理性疼痛大鼠的干预效应及机制

Effect of agmatine on diabetic neuropathic pain rats and its mechanism

目的观察胍丁胺(AGM)对糖尿病神经病理性疼痛(DNP)模型大鼠的干预效应,并探讨其可能的机制。方法将40只雄性SD大鼠随机分为5组各8只,除对照组外其余各组单次腹腔注射链脲佐菌素65 mg/kg构建糖尿病模型;足底触痛仪测量糖尿病大鼠机械缩足阈值(MWT)和热缩足潜伏期(TWL),降幅﹥20%基础阈值视为DNP大鼠模型制备成功。AGM-150组、AGM-300组、GP组分别腹腔注射AGM 150、300 mg/kg和加巴喷丁100 mg/kg,对照组、模型组腹腔注射等量生理盐水。分别于STZ注射前1 d(0 d),STZ注射后7、14、21、28 d,取尾静脉血检测血糖,足底触痛仪测量MWT、TWL;检查后处死大鼠取脊髓组织,采用Western blotting法检测磷酸化细胞外调节蛋白激酶(p-ERK)活性。结果与对照组比较,其他各组血糖均升高,MWT降低、TWL缩短(P均<0. 01)。与模型组比较,AGM-150组、AGM-300组于STZ注射后21、28 d血糖降低(P <0. 05或<0. 01),GP组血糖差异无统计学意义; AGM-150组、AGM-300组MWT(21、28 d)升高、TWL(28 d)延长(P均<0. 01),GP组21、28 d时MWT升高、TWL延长(P <0. 05或<0. 01);于STZ注射后28 d,模型组p-ERK蛋白表达量高于对照组(P <0. 05),AGM-150组、AGM-300组、GP组大鼠脊髓p-ERK表达量均低于模型组(P <0. 05或<0. 01)。结论 AGM具有明显地调节血糖及镇痛效应,其镇痛机制可能与其对血糖的调节及抑制脊髓ERK蛋白的活化有关。

Objective To investigate the intervention effect of agmatine (AGM) on diabetic neuropathic pain (DNP) rats and its mechanism. Methods Forty male SD rats were randomly divided into five groups ( n =8).Except the control group,the diabetes models were established by single intraperitoneal injection of streptozotocin 65 mg/kg in the other groups.Mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) in the diabetic rats were measured by plantar tenderness meter.A reduction of >20% basal pain threshold was considered successful in the preparation of the DNP rat model.Rats in the AGM-150 group,AGM-300 group and gabapentin (GP) group were intraperitoneally injected with AGM 150,300 mg/kg and GP 100 mg/kg.The rats in the control group and the model group were intraperitoneally injected with the same amount of normal saline.MWT,TWL and blood glucose was detected at 1 d before operation,and 7,14,21,28 d after STZ injection.The expression of phosphorylation of extracellular regulated protein kinase (p-ERK) was detected by Western blotting. Results Compared with the control group,the blood glucose of the other groups increased,and the MWT and TWL decreased (all P <0.01).Compared with the model group,the blood glucose of the AGM-150 group and AGM-300 group decreased at 21 and 28 d after STZ injection ( P <0.05 or P <0.01).There was no statistically significant difference in blood glucose between the GP group and the model group.MWT and TWL in the AGM-150 group,AGM-300 group and GP group increased ( P <0.05 or P <0.01).The expression of p-ERK protein in the model group was higher than that in the control group ( P <0.05).The expression of p-ERK of the AGM-150 group,AGM-300 group and GP group was lower than that of the model group at 28 d after STZ injection ( P <0.05 or P <0.01). Conclusion AGM may significantly regulate blood glucose and ease pain via depressing the expression of the activation of ERK protein in the spinal cord.