不同运动方式对2型糖尿病大鼠骨骼肌Rab5蛋白及糖代谢的影响*

目的: 探讨持续运动和间歇负重运动对2型糖尿病(T2DM)骨骼肌组织细胞形态、骨骼肌Rab5 mRNA及蛋白表达、骨骼肌糖代谢的影响。方法: SD大鼠选取8只为空白对照组(CR),其他采用高脂高糖饲料喂养6周后,腹腔注射STZ(35 mg/kg)构建T2DM模型。选取24只T2DM分3组(n=8),分别为:T2DM模型组(DRM)、持续运动组(DCRE)、间歇负重运动组(DWRE)。持续运动方案:为前1～2 周准备活动15 m/min(10 min)、运动20 m/min(40 min)、整理活动15 m/min(10 min),后3～8周为 18 m/min(10 min)、25 m/min(40 min)、15 m/min(10 min);间歇负重运动方案:采用负荷重量为15%(1～2周)、30%(3～4周)、45%(5～8周),运动均为15 m/min(5 min),共12组,组间休息3 min。8周后,通过HE观察骨骼肌病理形态变化,qRT-PCR检测骨骼肌Rab5、葡萄糖转运酶4(GLUT4)的mRNA表达,免疫荧光组化技术及Western blot检测骨骼肌Rab5的蛋白表达,ELISA检测血浆Rab5和糖化血红蛋白(GHb)浓度。结果: 相比CR,DRM存在骨骼肌病理损伤,骨骼肌Rab5mRNA及蛋白表达、GLUT4 mRNA表达均降低(P＜0.01),血浆Rab5和GHb均显著升高(P＜0.01);与DRM比较, DCRE、DWRE骨骼肌病理损伤均显著减轻,骨骼肌Rab5 mRNA及蛋白表达、GLUT4 mRNA表达均升高(P＜0.05,P＜0.01),血浆Rab5和GHb降低(P＜0.01);DCRE与DWRE组间均无统计学差异(P＞0.05)。结论: 2种运动方式均能改善2型糖尿病大鼠骨骼肌病理损伤,并可通过提高骨骼肌Rab5基因和蛋白表达从而增强 GLUT4转运能力,缓解骨骼肌糖代谢稳态失衡,但2种运动方式对骨骼肌Rab5蛋白和糖代谢的影响无明显差异性。

The effects of different exercise modes on Rab5 protein and glucose metabolism in skeletal muscle of type 2 diabetic mellitus rats

Objective: To investigate the effects of continuing exercise and load-bearing interval exercise on skeletal muscle tissue cell morphology, Ras-related proteins 5 (Rab5) mRNA and protein expression and glucose metabolism in skeletal muscle of type 2 diabetic mellitus (T2DM) rats. Methods: Eight SD rats were selected as controls group (CR), the others SD rats were fed with high fat and high sugar diet for 6 weeks before injecting STZ (35 mg/kg) to construct the T2DM model. Twenty-four T2DM rats were randomly devided into T2DM model group (DRM), continuing exercise group (DCRE) and load-bearing interval exercise group (DWRE), 8 rats in each group. DCRE exercise protocol, that was 15 m/min (10 min), 20 m/min (40 min), 15 m/min (10 min), during the first 1～2 weeks, and 18 m/min (10 min), 25 m/min (40 min), 15 m/min (10 min), during the second 3～8 weeks. DWRE exercise protocol: load weight 15% / 1～2 weeks, 30% / 3～4 weeks, 45% / 5～8 weeks, with 15 m/min (5 min), 12 groups and 3 min rest between groups. After 8 weeks, pathological and morphological changes of skeletal muscle were observed by HE. Rab5 and Glucose transporte 4 (GLUT4) mRNA expressions of skeletal muscle were tested by qRT-PCR. Rab5 protein expression in skeletal muscle was tested by immunofluorescence histochemistry and Western blot, and plasma Rab5 and Glycosylated Hemoglobin (GHb) concentrations were detected by ELISA. Results: Comparison with CR, DRM showed pathological damage of skeletal muscle, the expressions of Rab5 mRNA, protein and GLUT4 mRNA were all decreased in skeletal muscle (P＜0.01), the serum levels of Rab5 and GHb were both significantly elevated (P＜0.01). Comparison with DRM, both DCRE and DWRE significantly improved pathological damages of skeletal muscle, the expressions of Rab5 mRNA, protein and GLUT4 mRNA were all increased in skeletal muscle (P＜ 0.05, P＜0.01), the serum levels of Rab5 and GHb were decreased (P＜0.05, P＜0.01), and there was no statistical difference between DCRE and DWRE groups (P＞0.05). Conclusion: Two exercise modes can improve the pathological injury of skeletal muscle in type 2 diabetic rats, and enhance GLUT4 transport capacity by improving the expression of Rab5 gene and protein in skeletal muscle, and alleviate the imbalance of glucose metabolism homeostasis in skeletal muscle. However, there was no significant difference between the effects of two exercise modes on Rab5 protein and glucose metabolism in skeletal muscle.