ABSTRACT
Objective: The aim of this study was to investigate the anti-hyperglycemia effect and mechanism of aqueous extract from Gynostemma pentaphyllum (GP) leaves on STZ-induced diabetic rats. Methods: Diabetic rat models were established by intraperitoneal injection of streptozotocin (STZ, 50 mg/kg). A total of 21 successful SD male rats were randomly divided into model group (STZ). G. pentaphyllum leaves aqueous extract low dose group (GP•H2O-L, 100 mg/kg) and high dose group (GP•H2O-H, 500 mg/kg), another seven normal rats were taken as the control group. Blood samples were taken from the 2nd and 3rd weekends to detect plasma glucose and triglyceride concentrations; Real-time PCR was used to detect the expression of TNF-α and GLUT-4 mRNA in skeletal muscle; Western blotting was used to detect GLUT-4 total protein in skeletal muscle; The expression of GLUT-4 protein on skeletal muscle sarcolemma was observed by immunofluorescence staining. Results: The results showed that the food intake and water intake of the STZ group were significantly increased compared with the control group, while the body weight and skeletal muscle weight were obviously decreased; Plasma triglyceride and blood glucose concentrations and the expression of TNF-α mRNA in skeletal muscle were significantly increased, while the expression of GLUT-4 mRNA, GLUT-4 total protein and GLUT-4 protein in skeletal muscle sarcolemma was obviously decreased. Compared with the STZ group, the high-dose aqueous extract of G. pentaphyllum leaves significantly reduced the blood glucose of STZ-induced diabetic rats, and reversed the expression of TNF-α mRNA and GLUT-4 protein in skeletal muscle. Conclusion: The aqueous extract from G. pentaphyllum leaves could reduce hyperglycemia in STZ-induced diabetic rats, and its mechanism may be related to increasing the expression of GLUT-4 protein on skeletal muscle sarcolemma and inhibiting skeletal muscle inflammation.