Caffeine activates brown adipose tissue thermogenesis and metabolic rate in mice.

To clarify the effect of caffeine on brown adipose tissue (BAT) thermogenesis, we measured guanosine-5'-diphosphate (GDP) binding, a thermogenic indicator of BAT, and oxygen consumption in BAT mitochondria as well as BAT temperature and resting metabolic rate (RMR) in mice. Intraperitoneal injection of caffeine (60 mg/kg) significantly elevated BAT temperature with less effect on core temperature, and increased significantly GDP binding and oxygen consumption in BAT mitochondria, and RMR. These results suggest that caffeine activates BAT thermogenesis, which may contribute to the increase of RMR.