Figure 3. Enhanced bile acid signaling modulates intestinal fat absorption and increases energy expenditure.

(A) Body weight change (Δ) of adult female control (NTCP-heterozygous), NTCP-KO, TGR5-KO, and NTCP-TGR5–double KO (NTCP-TGR5–dKO) mice after a 15-week HFD (n = 6–14 per group). (B and C) WT and NTCP-KO mice (n = 5 per group) were fasted 4 to 5 hours, after which they received an i.p. injection with Poloxamer 407 (1 mg/kg) to inhibit lipoprotein lipase. At t = 0, mice were orally gavaged with olive oil containing tracer. Amounts of [³H]triolein and ³H activity in whole blood (B) and organs (C) were determined by liquid scintillation counting. Blood volume was estimated as 4.706% of total body weight. BAT, brown adipose tissue. (D) Per cage, 24-hour feces were collected from HFD-fed WT and NTCP-KO mice (n = 3–4 cages per group, 3–4 animals per cage), and remaining fecal calories were assessed by bomb calorimetry. (E and F) WT (n = 10) and NTCP-KO (n = 6) mice fed a HFD for 3 weeks were individually housed in fully automated calorimetric cages. Energy expenditure was calculated from O₂ consumption and the resting energy requirement (E), and lean and fat mass were assessed by NMR (F). Error bars show ± SEM; each dot represents an individual animal. *P < 0.05, calculated by 1-way ANOVA (A) or Student’s t test (B and F).