Ginsenoside Rb1 promotes adipogenesis in 3T3-L1 cells by enhancing PPARγ2 and C/EBPα gene expression

Evidence has accumulated that ginseng and its main active constituents, ginsenosides, possess anti-diabetic and insulin-sensitizing properties which may be partly realized by regulating adipocyte development and functions. In the present study, we explored the effect of ginsenoside Rb-1, the most abundant ginsenoside in ginseng root, on adipogenesis of 3T3-L1 cells. We found that with standard differentiation inducers, ginsenoside Rb-1 facilitated adipogenesis of 3T3-L1 preadipocytes in a dose-dependent manner; 10 mu M Rb-1 increased lipid accumulation by about 56%. Treatment of differentiating adipocytes with 10 mu M Rb, increased the expression of mRNA and protein of PPAR gamma(2) and C/EBP alpha, as well as mRNA of ap2, one of their target genes. After the treatment of differentiating adipocytes with Rb-1, basal and insulin-mediated glucose uptake was significantly augmented, accompanied by the up-regulation of mRNA and protein level of GLUT4, but not of GLUT1. In addition, ginsenoside Rb-1 also inhibited the proliferation of preconfluent 3T3-L1 preadipocytes. Our data indicate that anti-diabetic and insulin-sensitizing activities of ginsenosides, at least in part, are involved in the enhancing effect on PPAR-gamma(2) and C/EBP alpha expression, hence promoting adipogenesis. (c) 2006 Elsevier Inc. All rights reserved.