Antidiabetic Effect of Methanolic Extract from Berberis julianae Schneid. via Activation of AMP-Activated Protein Kinase in Type 2 Diabetic Mice.

We have investigated the antidiabetic effect and mechanism of methanolic extract of Berberis julianae Schneid. (BJSME) in STZ induced Type 2 diabetes mellitus mice. T2DM mice were induced by high fat diet and low dose streptozotocin (STZ). BJSME was orally administrated at the doses of 60, 120, and 240 mg/kg/d, for 21 days. Metformin was used as positive control drug. Food intake, body weight, plasma glucose, oral glucose tolerance test, insulin tolerance test, insulin, and blood-lipid content were measured. The effects of BJSME on the glucose transporter 4 (GLUT4) translocation in L6 myotubes and the GLUT4 protein expression in skeletal muscle as well as phosphorylation of the AMP-activated protein kinase (AMPK) in liver and muscle were examined. In vitro and in vivo results indicate that BJSME increased GLUT4 translocation by 1.8-fold and BJSME significantly improved the oral glucose tolerance and low density lipoprotein cholesterol (LDL-C) of serum and reduced body weight, glucose, and other related blood-lipid contents. The BJSME treatment also stimulated the phosphorylation of AMPK. Thus, BJSME seems to possess promising beneficial effects for the treatment of T2DM with the possible mechanism via stimulating AMPK activity.