Hypoglycemic and hypolipidemic effects of Epigynum auritum in high fat diet and streptozotocin-induced diabetic rats

Epigynum auritum is mainly distributed in Southwest China, and has been used as a "dai" folk medicine with promising Besides, the leaves and barks of E. auritum have detoxifying, analgesic and relieving swelling effects. Previous studies evidenced that E. auritum was rich in pregnanes and their glycosides. However, the hypoglycemic and hypolipidemic effects of the extract from E. auritum (EAE) and its molecular mechanism are still not studied.The aim of this study is to investigate the hypoglycemic and hypolipidemic effects of EAE on high-fat diet and streptozocin-induced type 2 diabetic rats.The high-fat diet and streptozocin induced type 2 diabetic model was established. The diabetic rats were treated with 70% ethanol extract of E. auritum (100 and 300 mg/kg/d) or metformin (DMBG, 100 mg/kg/d) every day for 4 weeks. Fasting blood glucose was recorded weekly. The phenotypic changes were evaluated by the measurement of biochemical indexes and immunohistochemical. The expressions of signaling-related proteins were explored by western blotting.EAE could effectively regulate the metabolism of glucose and lipids in diabetic rats by increasing insulin sensitivity. In addition, EAE ameliorated the oxidative stress damage and further mitigated the liver, kidney, and pancreatic damage. Mechanism research results show that EAE treatment increased the phosphorylation of Akt, AMPK and GSK-3β, up-regulated the expression of GLUT-2, GLUT-4 and PPAR-α, and reduced PPAR-γ and FAS expressions.EAE exhibited significant hypoglycemic and hypolipidemic effects in HFD/STZ-induced diabetes rats. The mechanism may be related to the effective upregulation of AMPK/Akt/GSK-3β pathway and the decreased expression of PPAR-γ and FAS. It could be a promising natural product with potential value for the development of drugs to prevent or treat type 2 diabetic.