Figure 2

TRPV1 activation promotes lipolysis both in mesenteric adipose tissue and 3T3-L1 preadipocytes. A. The weights of mesenteric, perirenal and testicular adipose tissues from WT and TRPV1^−/− mice fed a normal diet (ND), a high-fat diet (HD), or a high-fat plus capsaicin diet (HC). *P < 0.05 vs. ND, ^#P < 0.05 vs. HD. Values are expressed as the mean ± SEM, n = 6. B. Lipid droplets were visualized by Oil red O staining of 3T3-L1 preadipocytes on days 3, 5, and 8, with or without differentiation. The cells were exposed to a mixture of 1 mmol/L long-chain free fatty acids (FFA) in the presence of 1 μmol/L capsaicin (FFA + Cap), capsaicin plus 1 μmol/L capsazepine (FFA + Cap + Capz) or 150 μmol/L 18α-GA (FFA + Cap + 18α-GA) for 24 h. Red spots indicate lipid droplets in the cells. Images are representative of 3 separate experiments. The scale bar indicates 10 μm. C and D. Triglyceride and free fatty acid levels of 3T3-L1 preadipocytes after treatment with free fatty acids (FFA), FFA + capsaicin (Cap), FFA + capsaicin + capsazepine (Capz) or FFA + capsaicin + 18α-GA (18α-GA, 150 μmol/L) for 24 h. *P < 0.05 vs Con, ^#P < 0.05 vs FFA, ^ΔP < 0.05 vs Cap. Values are expressed as the mean ± SEM; n = 3 per group.