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目的:探讨糖尿病大鼠机械刺激诱发C纤维高频放电的机制。方法:24只SD大鼠随机分为对照组和模型组,模型组腹腔注射70 mg/kg链脲菌素制作糖尿病模型,对照组腹腔注射相同剂量的生理盐水。造模前48 h、造模后48 h和4周分别取尾静脉血测血糖浓度;造模前3 d,造模后3、7、14、21、28 d通过刺激后爪,采用vonFrey法测定大鼠50%机械缩爪阈值(PWT)。取造模后4周的大鼠,分离尾神经,测定传导速度以确定纤维类型,并给予60 s的阈上(100 g)机械刺激,记录单根C纤维的放电。在糖尿病大鼠的尾巴上暴露尾神经,给予100nmol/L的TTX 10 min后施加60 s阈上(100 g)机械刺激,观察并记录其放电。结果:造模后48 h模型组(n=12)随机血糖浓度高于16.7 mmol/L的比率为91.7%,与对照组(n=12)比较,模型组在48 h、4周时血糖明显增高;造模后3周模型组PWT明显低于对照组(P<0.05);糖尿病组大鼠C纤维对60 s阈上(100 g)机械刺激诱发的放电数明显高于对照组;加100 nmol/L低浓度的TTX后,糖尿病大鼠中C纤维对机械刺激的放电数明显减少(P<0.01)。结论:低浓度的TTX可以抑制糖尿病大鼠机械诱发的C纤维高频放电。
Objective: To investigate the mechanism of C-wave high-frequency discharge induced by mechanical stimulation in diabetic rats. Methods: Twenty-four SD rats were randomly divided into control group and model group. Diabetic model was induced by intraperitoneal injection of streptozotocin (70 mg / kg) in model group and normal saline in control group. Blood samples were taken from the tail vein 48 h before and 48 h after the model making, and 3 h before the model making. The hind paws were stimulated at 3, 7, 14, 21 and 28 d after modeling by von Frey method 50% mechanical paw withdrawal threshold (PWT) was measured in rats. The rats were sacrificed 4 weeks after model establishment, the caudate nerves were isolated, the conduction velocity was measured to determine the fiber type, and 60 s supratentorial (100 g) mechanical stimulation was used to record the discharge of single C fibers. The caudate nerves were exposed on the tail of diabetic rats, and 100 ng of suprachiasmatic (100 g) mechanical stimulation was applied after 100 nmol / L of TTX was given for 10 min. The discharge was observed and recorded. Results: Compared with the control group (n = 12), the blood glucose of the model group at 48 h and 4 weeks was significantly higher at 48 h after model establishment (n = 12) (P <0.05). Compared with the control group, the PWT of model group was significantly lower than that of the control group (P <0.05) After the low concentration of nmol / L TTX, the number of C fibers in diabetic rats significantly reduced the number of mechanical stimuli (P <0.01). CONCLUSION: Low concentration of TTX can inhibit C-fiber high-frequency discharge induced by mechanical stimulation in diabetic rats.