电针与预电针对糖尿病神经痛大鼠痛觉敏化及脊髓背角P2X7R表达的影响

Effect of electroacupuncture and pretreatment of electroacupuncture on pain sensitization and expression of P2X7R in spinal dorsal horn in rats with diabetic neuropathic pain

目的:观察腹腔注射链脲佐菌素(STZ)后糖尿病大鼠出现神经痛的时间及脊髓背角嘌呤能离子通道型受体7(P2X7R)表达情况,以及电针和预电针对糖尿病神经痛(DNP)大鼠热痛阈和脊髓背角P2X7R表达的影响,探讨电针防治DNP的可能作用机制。方法:第一部分:从64只雄性SD大鼠中随机选取30只作为对照组;余下大鼠以65 mg/kg剂量腹腔注射STZ(10 mg/mL)制备糖尿病模型,30只造模成功大鼠作为模型组。对照组和模型组各分为7、14、21 d 3个亚组,每亚组10只。分别于STZ注射后7、14、21 d记录各亚组大鼠体质量、空腹血糖及热痛阈;采用Western blot法检测各亚组大鼠脊髓背角P2X7R表达。第二部分:从35只雄性SD大鼠中随机选取8只作为空白组,剩余27只大鼠以65 mg/kg剂量腹腔注射STZ(10 mg/mL)制备糖尿病模型,24只造模成功大鼠随机分为糖尿病神经痛组、电针组和预电针组,每组8只。STZ注射后15~21 d,电针组于"足三里""昆仑"行电针干预,连续波,频率2 Hz,每次30 min,每天1次;预电针组干预方法同电针组,干预时间为STZ注射后8~14 d。记录各组大鼠STZ注射前,注射后7、14、21 d体质量、空腹血糖、热痛阈;采用Western blot法检测各组大鼠注射后21 d脊髓背角P2X7R表达。结果:第一部分:与对照组比较,模型组大鼠STZ注射后7、14、21 d体质量下降、空腹血糖升高(P<0.01),STZ注射后14、21 d热痛阈下降(P<0.05),STZ注射后7、14、21 d脊髓背角P2X7R表达增加(P<0.05,P<0.01)。第二部分:与空白组比较,糖尿病神经痛组大鼠STZ注射后7、14、21 d体质量下降、空腹血糖升高(P<0.01);与糖尿病神经痛组比较,预电针组大鼠STZ注射后14、21 d热痛阈升高(P<0.05),电针组大鼠STZ注射后21 d热痛阈升高(P<0.01),电针组及预电针组大鼠脊髓背角P2X7R表达减少(P<0.01)。结论:STZ注射后14 d大鼠出现糖尿病神经痛,电针不仅可治疗也可预防糖尿病神经痛发生,其作用机制可能与下调脊髓背角P2X7R表达有关。

Objective To observe the occurrence time of neuralgia and the expression of purinergic ligand-gated ion channel 7 receptor(P2 X7 R)in the dorsal horn of the spinal cord after intraperitoneal injection of streptozotocin(STZ)in diabetic rats,and to explore the effect of electroacupuncture(EA)and pretreatment of EA on the heat pain threshold and expression of P2 X7 R in the spinal dorsal horn in rats with diabetic neuropathic pain(DNP),and to explore the possible mechanism of EA for DNP.Methods PartⅠ:Thirty male SD rats were randomly selected from 64 male SD rats as the control group;the remaining rats were given intraperitoneal injection of STZ(10 mg/mL)at a dose of 65 mg/kg to establish the diabetes model,and 30 rats were successfully modeled as the model group.The control group and the model group were divided into three subgroups respectively at 7,14 and 21 days,with 10 rats in each subgroup.Body mass,fasting blood glucose(FBG)and thermal pain threshold were recorded at 7,14 and 21 days after injection;the expression of P2 X7 R in spinal dorsal horn was detected by Western blot.PartⅡ:Eight SD rats were randomly selected from 35 male SD rats as the blank group,and the remaining 27 rats were given intraperitoneal injection of STZ(10 mg/mL)at a dose of 65 mg/kg to establish the diabetes model.The 24 rats with successful diabetes model were randomly divided into a DNP group,an EA group and a pre-EA group,8 rats in each group.Fifteen to 21 days after STZ injection,the EA group received EA at"Zusanli"(ST 36)and"Kunlun"(BL 60),continuous wave,frequency of 2 Hz,30 min each time,once a day;the intervention method in the pre-EA group was the same as that in the EA group.The intervention time was 8 to 14 days after STZ injection.The body mass,FBG and thermal pain threshold were recorded before STZ injection and 7,14 and 21 days after STZ injection;the expression of P2 X7 R in spinal dorsal horn was detected by Western blot 21 days after injection.Results PartⅠ:Compared with the control group,in the model group,the body mass was decreased and FBG was increased 7,14 and 21 days after STZ injection(P<0.01),and the thermal pain threshold was decreased 14 and 21 days after STZ injection(P<0.05),and the expression of P2 X7 R in spinal dorsal horn was increased 7,14 and 21 days after STZ injection(P<0.05,P<0.01).PartⅡ:Compared with the blank group,in the DNP group,the body mass was decreased and fasting blood glucose were increased 7,14 and 21 days after STZ injection(P<0.01).Compared with the DNP group,in the pre-EA group,the heat pain threshold was increased 14 and 21 days after STZ injection(P<0.05),while in the EA group,the heat pain threshold was increased 21 days after STZ injection(P<0.01),and the expression of P2 X7 R in the dorsal horn in the EA group and the pre-EA group was decreased(P<0.01).Conclusion The diabetic neuropathic pain is observed 14 days after STZ injection.EA could not only treat but also prevent the occurrence of DNP,and its mechanism may be related to down-regulation of P2 X7 R expression in the dorsal horn of the spinal cord.