糖尿病早期大鼠坐骨神经电生理改变及胰岛素的影响

Electrophysiological changes of sciatic nerve in early diabetic rats and the effect of insulin treatment

目的:观察糖尿病早期大鼠坐骨神经电生理改变及胰岛素对其的影响。方法:实验于2005-09在南通大学药理教研室完成。从18周龄健康雄性SD大鼠36只中随机数字表法取28只造模,8只作为正常对照组。给予大鼠一次性腹腔注射链脲菌素造成胰岛素依赖性糖尿病模型,正常对照组给予等体积的柠檬酸盐缓冲液。给药72h后造模大鼠尾静脉取血,邻甲苯胺法测定血糖浓度,非空腹血糖大于16.0mmol/L纳入糖尿病模型。将纳入糖尿病模型的大鼠随机分为糖尿病模型组和胰岛素治疗组。造模成功后的第2天,每天给予胰岛素治疗组大鼠皮下注射精蛋白锌胰岛素注射液(长效胰岛素,40U/mL),给药时间在下午5点左右,胰岛素起初剂量4U/只,次日上午测定其血糖值,控制大鼠非空腹血糖值在10mmol/L以下(不低于3.9mmol/L),调整胰岛素用量为4～6U。2周时停止给药,并再次测定大鼠的血糖和体质量。糖尿病模型组不作任何处理。糖尿病模型组与正常对照组与胰岛素治疗组同时间进行血糖和体质量的测定。麻醉各组大鼠分离、暴露坐骨神经,测定其感觉神经动作电位潜伏期、波幅及传导速度。结果数据行方差分析,两两比较使用Scheffe检验。结果:在28只造模SD大鼠给予链脲菌素后第72h,有15只大鼠血糖值为16.05～20.89mmol/L,超过16.0mmol/L,造模成功,纳入糖尿病模型。将造模成功的糖尿病模型大鼠分为糖尿病模型组8只,胰岛素治疗组7只;和正常对照组大鼠8只一起进入结果分析。①糖尿病模型组坐骨神经感觉神经动作电位的传导速度与波幅和正常对照组相比显著降低,差异有显著性意义[(40.34±1.68),(55.47±9.05)m/s,P<0.01]O[(510.73±22.10),(637.37±29.28)μV,P<0.01]O潜伏期延长[(1.54±0.13),(1.19±0.13)ms,P<0.01]。给予胰岛素治疗后能有效逆转这些变化,坐骨神经感觉神经动作电位传导速度增加至(48.57±1.86)m/s,波幅上升至(593.72±22.62)μV,潜伏期缩短至(1.31±0.06)ms,与糖尿病模型组比较差异有显著性意义。②造模后2周糖尿病模型组血糖值显著高于正常对照组,差异有显著性意义[(20.1±2.0),(5.1±0.6)mmol/L,P<0.01];给予胰岛素治疗后血糖值显著降低至(6.6±1.8)mmol/L,与糖尿病模型组比较差异有显著性意义(P<0.01)。结论:在糖尿病早期(2周)即存在感觉神经功能的损害,起始因素为高血糖,通过胰岛素控制血糖后,能有效防止神经病损。

AIM To observe the electrophysiological changes of sciatic nerve in early diabetic rats and the effects of insulin treatment on them. METHODS： The experiment was conducted in the Department of Pharmacology, Nantong University in September 2005. Thirty-six healthy male SD rats, aged 18 months old were selected, and 28 out of which were randomly selected to conduct modeling, and 8 were taken as normal control group. Insulin-dependent diabetic model were induced with an intraperitoneul injection of streptozotncin （STZ）, and rats in the normal control group were given of citrate buffer solution at the same volume. At 72 hours after modeling, blood was obtained from the vena caudalis of rats, and the blood glucose concentration （BGC） was determined with o-toluidine method. Bats with the non-fasting blood glucose greater than 16.0 mmol/L were enrolled in the diabetic model, which were randomly divided into diabetic model group and insulin treatment group. On the second day after modeling, rats in the insulin treatment group were subeutaneouly injected with protamine zinc insulin injection （long-acting insulins, 40 U/mL） at over 5 PM per day. The initial dose of insulin was 4 U/piece, and the blood glucose was determined in the next day. The fasting blood glucose of rats was controlled below 10 mmoL/L （no less than 3.9 mmol/L）, and the dosage of insulin was regulated at 4-6 U. The administration was ceased on the 24 week, and the blood glucose and body mass of rats were reinspected. The sciatic nerve in rats of all anesthetized group were isolated and exposed, and the latency, amplitude of wave and the nerve conduction velncity of sensory nerve action potential were detected respectively. Differences in data were compared with analysis of variance, and differences between each two groups were compared with Scheffe test. RESULTS： On the 72^nd hour after administration of STZ in 28 SD rats that received madding, the blood glucose in 15 of them were 16.05- 20.89 mmol/L. Those with the blood glucose over 16.0 mmol/L were taken as successful madding and involved in the diabetic model. A total of 8 rats in the diabetic model group, 7 rats in the insulin treatment group and 8 rats in the normal control group were involved in the analysis of results.（1）The nerve conduction velncity and amplitude of wave of sensory nerve action potential in the diabetic model group were significantly reduced than in the normal control group, and the differencas were obvious [（40.34±1.68）, （55.47±9.05） m/s,P 〈 0.01]; [（510.73 ±22.10）, （637.37 ±29.28） μV,P 〈 0.01] with latency prolonged [（1.54±0.13）, （1.19±0.13） ms, P 〈 0.01]. Insulin therapy could effectively reverse these changes, and the conduction velncity of sensory nerve action potential of sciatic nerve increased to （4837±1.86） m/s, and the wave a/nplitude ascended to（593.72±22.62）μV,and the latency was shortened to （1.31 ±0.06） ms.Compared with diabetic model group, there were remarkable differences.（2）At 2 weeks after modeling, the blood glucose was significantly higher in the diabetic model group than in the normal control group with obvious differences [（20.1±2.0）, （5.1 ±0.6） mmol/L,P 〈 0.01], and the blood glucose significantly decreased to （6.6±1.8） mmol/L after adiministration of insulin, which was markedly different from the diabetic model group （P 〈 0.01）. CONCLUSION： There are functional deficits of sensory nerve in early stage of diabetes （2^nd week）, the cause of which is hyperglycemia, while the impairment of nerve can be effectively prevented by controlling the blood glucose with insulin.