Fig. 2. Butein increases energy expenditure in HFD-fed obese mice.

a, b Energy expenditure was measured by oxygen consumption and carbon dioxide production. a O₂ consumption and b CO₂ production rates of control (n = 6) and butein-injected mice (15 mg/kg per day, n = 6) were measured by indirect calorimetry using CLAMS after 3 weeks on HFD (n = 6 per group). Energy expenditure was measured before body weights started to diverge. Bar graph (right panel) represents the average of O₂ consumption or CO₂ production in each group. c Rectal temperature for 24 h was measured in mice treated with control or butein. d, e Increased Ucp1 protein expression in adipose tissue from butein-treated mice. d Representatives of Ucp1 staining in iWAT and BAT of control or butein-treated mice for 8 weeks are shown. Scale bar, 50 µm. e Expression levels of Ucp1 protein in iWAT of control (n = 4) and butein-injected mice (15 mg/kg per day, n = 4) were determined by western blotting and quantified. f Respiratory exchange ratio (RER), g total physical activities of control- and butein-treated mice for 3 weeks (n = 6 per group). Data represent mean ± s.e.m. and statistically significant differences between control- andr butein-treated mice were determined by Student’s t-test. Statistically significant differences were determined by two-way ANOVA for the rectal temperature. *P < 0.05; **P < 0.005; ***P < 0.0005