Fig. 6. SIRT1 LKO mice are susceptible to developing obesity with increased adiposity and decreased total oxygen consumption and energy expenditure.

A. Chow-fed SIRT1 LKO mice at 6- and 7-months of age (n = 8) gain more body weight. Body weight curves of WT and SIRT1 LKO mice over a 15-month period (n = 8–16). B. A representative photograph of increased adiposity and adipocyte size in white adipose tissue (WAT) of SIRT1 LKO mice. C. Body composition analysis of WT and SIRT1 LKO mice. D. Food intake (n = 10-12) and body temperature (n = 6) are similar between WT and SIRT1 LKO mice. E. The rates of VO₂, VCO₂, and energy expenditure are measured by comprehensive metabolic monitoring in mice (n = 4) over a 24-h period with food and over a 24-h fast and normalized to lean body mass. The upper panels represent circadian changes in metabolic parameters in mice in the fed state during light and dark cycles, as indicated by the white and gray areas. The lower panels represent metabolic rates in mice in fed and fasted states. F. Respiratory quotient (RQ) and locomotor activity are determined in metabolic cages. The physical activity is expressed as total counts measured by summing X and Y beam breaks, and the bar graph represents average locomotor activity over a 12-h block of light and dark phases. *P<0.05, vs. WT mice.