糖尿病周围神经病变对大鼠局麻药外周神经毒性的影响

Effect of diabetic peripheral neuropathy on peripheral neurotoxicity induced by local anesthetics in rats

目的评价糖尿病周围神经病变对大鼠局麻药外周神经毒性的影响。方法SPF级健康成年雄性sD大鼠60只，6周龄，体重150～180g，采用随机数字表法分为对照组（n=18）和糖尿病神经周围病变组（n=42）。糖尿病组高脂高糖饮食8周，腹腔注射链脲佐菌素（STZ）30mg／kg，持续测定血糖和血清胰岛素，血糖≥16．7mmol／L为大鼠糖尿病模型制备成功。采用yonFrey纤维丝和足底测痛仪分别测定机械痛阈和热痛阈，注射STZ后大鼠足底触痛觉和热痛觉从敏感逐渐转为迟钝，选择注射STZ后4周痛觉过敏表现显著的大鼠作为早期糖尿病组，8周后痛觉迟钝表现显著的大鼠作为晚期糖尿病组，对于早期或晚期糖尿病大鼠进行实验，同龄普通sD大鼠作为对照组。采用2％利多卡因0．2ml行左侧坐骨神经阻滞，于坐骨神经阻滞前及阻滞后1周，分别行神经传导速度和F波最小潜伏期测定和神经病理学分析，记录坐骨神经局麻药阻滞时间。结果与阻滞前比较，晚期糖尿病大鼠坐骨神经阻滞后神经传导速度降低，F波最小潜伏期延长（P〈0．05）；与对照组比较，晚期糖尿病组坐骨神经阻滞时间明显延长（P〈0．05）。结论糖尿病周围神经病变加重大鼠局麻药外周神经毒性。

Objective To evaluate the effect of diabetic peripheral neuropathy on peripheral neuro- toxicity induced by local anesthetics in rats. Methods Sixty healthy adult male SPF Sprague-Dawley rats, aged 6 weeks, weighing 150-180 g, were divided into either control group （n = 18） or diabetic peripheral neuropathy group （ n = 42） using a random number table. The rats were fed a high-fat and high-sucrose diet for 8 weeks, and streptozotocin （STZ） 30 mg/kg was injected intraperitoneally to induce diabetes mellitus which was confirmed by blood glucose level≥ 16.7 mmol/L. The mechanical paw withdrawal threshold to von Frey filament stimulation and thermal paw withdrawal threshold were measured. The decrease in reaction thresholds to thermal and mechanical stimuli （changing from sensitivity to insensitivity） was observed after STZ injection. At 4 weeks after STZ injection, the rats showing a marked hyperalgesia served as early dia- betic group. At 8 weeks after STZ injection, the rats showing a marked insensitivity to pain served as late diabetic group. Experiments were carried out in early or late diabetic rats, and ordinary Sprague-Dawley rats of the same age were used as control group. Left sciatic nerve block was performed with 2% lidocaine 0.2 ml. Before the sciatic nerve block and at 1 week after the sciatic nerve block, the nerve conduction ve- locity of the left sciatic nerve and F-wave minimal latency were measured, and the sciatic nerve block timewas recorded. Results Compared with the baseline before block, the nerve conduction velocity was signif- icantly decreased, and the F-wave minimal latency was prolonged in late diabetic rats （P〈0.05）. Com- pared with control group, the sciatic nerve block time was significantly prolonged in late diabetic group （P〈0.05）. Conclusion Diabetic peripheral neuropathy aggravates peripheral neurotoxicity induced by lo- cal anesthetics in rats.