Vernonia amygdalina Delile extract inhibits the hepatic gluconeogenesis through the activation of adenosine-5'monophosph kinase

Aims: It has been reported that Vernonia amygdalina Delile(VA) presents an anti-diabetic effect, and the effect of VA on lowering glucose is formulated via suppressing the expression of the key hepatic gluconeogenesis enzyme. Therefore, we further explored the probable mechanism of VA on dismissing hepatic gluconeogenesis through the activation of adenosine-5' monophosphate kinase (AMPK) in vivo and in vitro. Methods: We developed type 2 diabetic mice with STZ and oral administration with VA (50 mg/kg, 100 mg/kg and 150 mg/kg) once a day for 6 weeks. Fasting blood glucose (FBG), fasting insulin (FINS) and oral glucose tolerance tests (OGTT) were conducted. The expression levels of AMPK, phosphoenolpyruvate carboxykinase (PEPCK) and Glucose-6-phosphatase (G6Pase) proteins in live were evaluated by western blot. Then, we further explored the mechanism of VA on hepatic gluconeogenesis in vitro experiments. Glucose production and the expression of AMPK, PEPCK and G6Pase proteins were detected after VA treatment with the presence of the AMPK inhibitor Compound C. Key findings: VA reduced FBG and caused a significant improvement in glucose tolerance and insulin resistance (HOMA-IR) in STZ-induced mice. VA inhibited the elevated expression of gluconeogenesis key enzymes (PEPCK and G6Pase) and up-regulated AMPK activity in liver. In palmitic acid (PA)-induced HepG2 cells, VA decreased glucose production and the expression of PEPCK and G6Pase proteins, also activated AMPK pathway. The effects of VA on gluconeogenesis could be reversed by Compound C. Conclusion: These results reveal that VA suppresses hepatic gluconeogenesis at least partially through activating the AMPK.