Differential effects of ginsenosides Rb1 and Rg3 on adipogenic and myogenic differentiation

Abstract

Ginsenosides Rb1 and Rg3, the main bioactive constituents in fresh and steamed Panax ginseng, have been shown to exert protective effects against hyperglycemia and diabetes. In the present study, we tested the effects of Rb1 and Rg3 on adipogenic and myogenic gene expression and differentiation using 3T3‐L1 and C2C12 cells. The changes in levels of lipid, mRNA expression of key adipogenic and myogenic transcription factors were determined using semi‐quantitative RT‐PCR. Compared to control, both ginsenosides Rb1 and Rg3 enhanced differentiation of 3T3‐L1 preadipcytes in parallel with increased PPARγ mRNA, a key transcription factor for adipogenic determination. This correlated with increased expression of aP2 mRNA, a PPARγ‐regulated late marker gene. Moreover, ginsenosides Rg3 dose‐dependently stimulated myogenesis by increasing expression of both myogenin, a critical myogenic transcription factor, and MHC1, a marker gene for myotube formation. However, Rb1 was without effects on both myogenic marker gene expression and differentiation. These results indicate that the anti‐diabetic activities of ginseng may be attributable for Rb1 and Rg3 through a mechanism that involves activation of PPARγ in addition to the beneficial effect of Rg3 in stimulating myogenesis.