榼藤子总皂苷抗糖尿病作用机制的初步研究

目的:探讨榼藤子总皂苷对2型糖尿病大鼠胰岛形态及骨骼肌PI3K通路相关蛋白表达的影响。方法:通过高脂饲料喂养结合注射小剂量链脲佐菌素(STZ)建立2型糖尿病大鼠模型。实验大鼠随机分为正常对照组、模型组、阳性对照组(二甲双胍,200 mg.kg-1)、榼藤子总皂苷低、高(25,50 mg.kg-1)剂量组。治疗3周后对各组大鼠胰腺HE染色病理切片胰岛形态、数目等进行观察比较,采用Western blot方法检测各组大鼠骨骼肌组织中胰岛素受体底物-1(IRS-1)、磷脂酰肌醇3激酶(PI3K)、蛋白酪氨酸磷酸酶-1B(PTP-1B)和葡萄糖转运子4(GLUT4)等蛋白的表达水平。结果:同模型组相比,榼藤子总皂苷各给药组胰腺组织病理切片均结构相对正常、胰泡细胞清晰可见、被膜结构完整,胰岛数目均接近于对照组;同时上述各给药组大鼠骨骼肌组织中IRS-1,PI3K和GLUT4蛋白表达水平均较模型组有所上调,PTP-1B蛋白表达水平均较模型组有所下调。结论:榼藤子总皂苷对2型糖尿病大鼠胰腺组织具有保护作用,并对骨骼肌组织中蛋白的异常表达具有干预作用。

Preliminary study on mechanisms of total saponins from Entada phaseoloides against diabetes

Objective: To study the effect of total saponins from Entada phaseoloides (TSEP) on islet morphology and skeletal muscle PI3K pathway-related protein expression of type 2 diabetic rats. Method: Type 2 diabetic rats were induced by high-fat diet and low-dose streptozotocin and then randomly divided into 5 groups, i.e. the normal control, the model group, the positive control drug (200 mg·kg^-1 metformin), the low-dose TSEP (25 mg·kg^-1) group and the high-dose TSEP (50 mg·kg^-1). Three weeks later, the islet morphology of rat pancreas were observed by HE staining, and protein expressions of insulin receptor substrate-1 (IRS-1), phosphatidylinositol 3-kinase (PI3K), protein tyrosine phosphatase-1B (PTP-1B) and glucose transporter 4 (GLUT4) in rat skeletal muscle were detected by Western blot. Result: Compared with the modal group, TSEP administration groups showed relatively normal structures, clear pancreatic cells and intact capsula structures in pancreatic tissue pathological sections, with the number of pancreatic islets close to the normal control group. Meanwhile, above TSEP administration groups showed increased IRS-1, PI3K and GLUT4 protein expressions in their skeletal muscle tissues and decreased PTP-1B protein expression compared with the model group. Conclusion: TSEP has an effect on protecting pancreatic tissues of type 2 diabetic rats and intervening in abnormal expression of proteins in skeletal muscle tissues.