摘要目的 评价糖尿病因素对巴氯芬抑制神经痛大鼠脊髓谷氨酸能神经元突触后电流(mEPSCs)的影响.方法 雄性SD大鼠30只,4周龄,体重150 ～ 170 g,采用随机数字表法,将其分为2组(n=15):对照组(C组)和糖尿病神经痛组(D组).D组腹腔注射链脲佐菌素50 mg/kg制备大鼠糖尿病神经痛模型,C组腹腔注射等容量生理盐水.腹腔注射后28 d时空腹血糖＞16.7 mmol/L且机械痛阈＜4g为模型制备成功.随后处死大鼠取脊髓,制备脊髓薄片,采用全细胞膜片钳技术记录脊髓神经元谷氨酸能mEPSCs,每组分别记录20个神经元.细胞封接后稳定5 min,灌流液中通过微量泵加入巴氯芬,终浓度分别为1、10、20、50 μmol/L,每两个浓度间隔5 min.于给药前、给药后即刻和洗脱后5 min分别记录神经元谷氨酸能mEPSCs的频率和强度,计算巴氯芬对神经元谷氨酸能mEPSCs的抑制率.结果 与C组比较,D组各浓度下神经元谷氨酸能mEPSCs频率增加,抑制率降低(P＜0.05),强度差异无统计学意义(P＞0.05).结论 糖尿病因素降低了巴氯芬对大鼠神经痛的镇痛效应,与抑制脊髓谷氨酸能神经元mEPSCs有关.

abstractsObjective To evaluate the effect of diabetes on baclofen-induced inhibition of miniature excitatory postsynaptic currents (mEPSCs) in spinal glutamatergic neurons in rats with neuropathic pain.Methods Thirty male Sprague-Dawley rats,aged 4 weeks,weighing 150-170 g,were randomly divided into 2 groups (n＝15 each group):control group (C group) and diabetic neuropathic pain group (D group).Diabetic neuropathic pain was induced by intraperitoneal injection of streptozotocin 50 mg/kg and confirmed 28 days later by blood glucose ＞ 16.7 mmol/L and pain threshold ＜ 4 g in group D,while the rats received the equal volume of normal saline in C group.The animals were anesthetized with intraperitoneal 10％ chloral hydrate 50 mg/kg.The rats were then sacrificed and lumbar segments (L1.5) of the spinal cord were removed for slice preparations.Glutamatergic mEPSCs in lamina Ⅱ neurons were recorded by using whole-cell patch-clamp technique and 20 neurons located in lamina Ⅱ of the spinal cord were recorded in each group.The cells stabilized for 30 min after sealing,and then baclofen with the final concentrations of 1,10,20,50 μmol/L was added to the perfusion solution at 5 min intervals followed by washout.The frequency and intensity of glutamatergic mEPSCs were recorded immediately before and after administration and at 5 min after washout.The inhibitory effect of baclofen on glutamatergic mEPSCs was measured and the inhibitory rate was calculated.Results Compared with group C,the frequency of glutamatergic mEPSCs was significantly increased and the inhibitory rate was decreased under each concentration (P ＜ 0.05),and no significant change was found in the intensity of mEPSCs under each concentration in D group (P ＞ 0.05).Conclusion Diabetes decreases baclofen-induced analgesic effect in rats with neuropathic pain,which is related to inhibition of mEPSCs in spinal glutamatergic neurons.