Figure 1. Increase in Energy Requirement and Thermogenic Activity of the Gut and Visceral Mesenteric Fat after RYGB.
(A) Average body weights of RYGB- and SG-operated mice—2 weeks after surgery—before undergoing resting metabolic rate (RMR) measurements using a combined direct and indirect calorimeter. One-way ANOVA followed by Tukey’s test, **p < 0.01, ***p < 0.001, RYGB/SG versus sham.
(B) Total RMR (kcal/h measured by direct calorimetry in RYGB-, SG-, and sham-operated mice) corrected for weight factor with analysis of covariance (ANCOVA).
(C) Anaerobic RMR—calculated from total RMR (measured by direct calorimetry) and aerobic RMR (measured by respirometry or indirect calorimetry)—in RYGB- and SG-operated mice. Aerobic and anaerobic RMR expressed as percentage of total RMR in RYGB and SG mice. *p < 0.05, **p < 0.01 RYGB versus sham; #p < 0.05 RYGB versus SG (B and C). Mean ± SEM. Sham n = 13, RYGB n = 6, SG n = 4–5 (A–C).
(D) Relative Ucp1 mRNA expression in brown adipose tissue (BAT), visceral mesenteric white adipose tissue (vWAT), and subcutaneous white adipose tissue (scWAT) of RYGB- versus sham-operated mice.
(E) Relative Prdm16 mRNA expression in vWAT and scWAT of RYGB- versus sham-operated mice.
(F) In vivo recording of surface body temperature by infrared camera in RYGB- and sham-operated mice while on light treadmill exercise during light and dark cycles (4 weeks after surgery).
(G) UCP1 protein expression—assessed by immunohistochemistry (IHC)—in the vWAT of DIO mice 5 weeks post-RYGB surgery. Scale bar, 100 μm (top); 50 μm (bottom).
(H) 18Fluoro-deoxyglucose (FDG) uptake analysis under positron emission tomography (PET) scan imaging before and after surgery in RYGB-operated mice and weight-matched sham (WM-sham) counterparts. Average standardized uptake values (SUVs) of the small intestine in RYGB and WM-sham. Mean ± SEM. Sham n = 7–9, RYGB n = 6–8. *p < 0.05, **p < 0.01 RYGB versus sham or WM-sham by t test (D–H).