Comprehensive phenotyping of mouse metabolism

Body composition of fat and lean mass was measured by nuclear magnetic resonance (NMR) spectroscopy (Bruker Minispec LF90II, Bruker, Billerica, USA) as previously reported and normalized to total body weight (28 (link)). The volume of oxygen consumption (VO₂), carbon dioxide production (VCO₂), spontaneous motor activity and food intake were measured using the Comprehensive Laboratory Monitoring System (CLAMS) (Columbus Instruments, Columbus, USA) (28 (link)). The respiratory exchange ratio (RER) was calculated from the ratio of VCO₂ to VO₂. Mice were individually placed into the sealed chambers with free access to food and water. The study was carried out in a room set at 22^oC with 12-12 hr (6:00 am ~ 6:00 pm) light-dark cycles, and the measurements were carried out continuously for 72 hours after a 24 h acclimatization period. The data were averaged over 72 hr. Rectal body temperatures were measured by a BAT-12 thermometer (Physitemp, USA). Blood pressure was recorded in conscious, restrained mice at age of 7 weeks and 14 weeks using the CODA tail cuff blood pressure monitoring system (Kent Scientific, USA).