Effect of astragaloside IV on hepatic glucose‐regulating enzymes in diabetic mice induced by a high‐fat diet and streptozotocin

Abstract Aim: Hepatic glycogen phosphorylase (GP) and glucose‐6‐phosphatase (G6Pase) are important in control of blood glucose homeostasis, and are considered to be potential targets for antidiabetic drugs. Astragaloside IV has been reported to have a hypoglycemic effect. However, the biochemical mechanisms by which astragaloside IV regulates hepatic glucose‐metabolizing enzymes remain unknown. The present study examines whether GP and G6Pase mediate the hypoglycemic effect of astragaloside IV. Methods: Type 2 diabetic mice were treated with astragaloside IV for 2 weeks. Blood glucose and insulin levels were measured by a glucometer and the ELISA method, respectively. Total cholesterol (TC) and triglyceride (TG) levels were determined using Labassay TM kits. Activities of hepatic GP and G6Pase were measured by the glucose‐6‐phosphate dehydrogenase‐coupled reaction. The mRNA and protein levels of both enzymes were determined by real‐time RT‐PCR and Western blotting. Results: Astragaloside IV at 25 and 50 mg/kg significally decreased the blood glucose, TG and insulin levels, and inhibited the mRNA and protein expression as well as enzyme activity of GP and G6Pase in diabetic mice. Conclusions: Astragaloside IV exhibited a hypoglycemic effect in diabetic mice. The hypoglycemic effect of this compound may be explained, in part, by its inhibition of hepatic GP and G6Pase activities. Copyright © 2009 John Wiley & Sons, Ltd.