Neferine enhances insulin sensitivity in insulin resistant rats

Ethnopharmacological relevance: Neferine was isolated from green seed embryo of Nelumbo nucifera Gaertn which has been used as an anti-obesity agent in traditional Chinese herbal medicine. Aim of the study: This study was conducted to investigate the effects of neferine on enhancing insulin sensitivity in insulin resistant rats compared with rosiglitazone and to potentially reveal its role in mediating the anti-obesity properties of Nelumbo nucifera Gaertn. Materials and methods: Fasting blood glucose (FBG), fasting blood insulin (FINS), triglycerides (TG) and tumor necrosis factor-alpha (TNF-alpha) were measured, and the oral glucose tolerance test for 2-h plasma glucose level (2-h PG) was carried out. The glucose infusion rate (GIR) was used to measure the insulin sensitivity by hyperinsulinemic euglycemic clamp technique. Results: The levels of FBG, FINS, TG, TNF-alpha and 2-h PG all decreased significantly in the rosiglitazone and neferine groups compared with the insulin resistance (IR) model group. Neferine diminished the 2-h PG more than did rosiglitazone treatment. Compared to the IR model group, the treatments of neferine and rosiglitazone remarkably increased GIRs but no difference between these two treatments themselves was evident. Conclusions: These data demonstrate that neferine has effects similar to rosiglitazone in decreasing fasting blood glucose, insulin, TG, TNF-alpha and enhancing insulin sensitivity in insulin resistant rats. (C) 2009 Elsevier Ireland Ltd. All rights reserved.