Effects of cigarette smoke on norepinephrine turnover and thermogenesis in brown adipose tissue in MSG-induced obese mice.

To clarify whether cigarette smoke stimulates the sympathetic nervous system (SNS) and thermogenesis in interscapular brown adipose tissue (IBAT), we measured norepinephrine (NE) turnover, an indicator of SNS activity, guanosine-5'-diphosphate (GDP) binding, a thermogenic indicator, and oxygen consumption in IBAT in monosodium-L-glutamate (MSG)-induced obese and saline control mice following a two-week exposure to cigarette smoke. Cigarette smoke significantly increased NE turnover, GDP binding and oxygen consumption in IBAT, and significantly reduced body weight in MSG obese mice as well as in control mice. However, food intake was unchanged in the MSG group. These results suggest that cigarette smoke stimulates NE turnover and thermogenesis in BAT, which contribute to the mitigation of obesity.