Ginsenoside Rb1 Facilitates Browning by Repressing Wnt/β-Catenin Signaling in 3T3-L1 Adipocytes

BACKGROUND: The discovery of browning in white adipose tissue has provided new ideas for treating obesity. Many studies have reported that ginsenoside Rb1 (G-Rb1) has activity against diabetes, inflammation, and obesity, but further investigation is needed on the effect and mechanism of G-Rb1 on browning. MATERIAL/METHODS: We treated 3T3-L1 adipocytes with 0–200 μM G-Rb1, and 0.5 μM Compound 3f and 30 μM SKL2001 were used to activate Wnt/β-catenin signaling. Adipocyte activity was evaluated by Cell Counting Kit-8. Oil Red O staining was used to detect the lipid droplets. Quantitative real-time polymerase chain reaction was used to measure the expression of Cd-137, Cited-1, Txb-1, Prdm-16, and Ucp-1 mRNA. Western blotting was used to measure the expression of Ucp-1, pGSK-3β (Ser 9), GSK-3β, and β-catenin proteins. The expression of Ucp-1 was also detected with immunofluorescence. RESULTS: Adipocyte activity was not affected by 0–100 μM G-Rb1. However, G-Rb1 dose-dependently reduced the accumulation of lipid droplets; increased the expression of Cd-137, Cited-1, Txb-1, Prdm-16, and Ucp-1 mRNA; and increased the expression of Ucp-1, pGSK-3β (Ser 9), GSK- 3β, and β-catenin proteins. The accumulation of lipid droplets and the expression of Ucp-1 protein decreased as β-catenin increased. CONCLUSIONS: G-Rb1 at various concentrations (0–100 μM) promoted the browning of adipocytes in a dose-dependent manner. Further, we confirmed that activation of Wnt/β-catenin signaling could inhibit browning. Therefore, the browning promoted by G-Rb1 may be associated with the inhibition of Wnt/β-catenin signaling.