Cold acclimation increases the contribution of brown adipose tissue‐derived thermogenesis in adult humans

Abstract

Recent studies examining brown adipose tissue (BAT) metabolism in adult humans have provided convincing evidence that it can significantly contribute to cold‐induced thermogenesis under acute mild‐cold exposure. Although, many mammalian models have demonstrated the adaptability of this tissue through chronic cold exposure, little is known about its plasticity in humans. Using electromyography combined with positron emission tomography with 11C‐acetate and 18F‐fluorodeoxyglucose, shivering intensity and BAT oxidative metabolism and glucose uptake prior to and following four weeks of cold acclimation were examined. Non‐acclimated men were exposed to 10°C, two hours daily for four weeks (5 days/week), using a liquid‐conditioned suit (LCS). Preliminary data suggests a 5‐fold increase in BAT oxidative metabolism (from 0.005±0.004to 0.025±0.007 sec−1, n=3) resulting in a ~40% decrease in shivering intensity (from 3.2±1.4 to 2.0±1.3 %MVC, n=3), through four weeks of cold‐acclimation, despite similar 1.8‐fold increases in cold‐induced energy expenditure (10.6±1.4 and 10.3±1.3 kJ·min−1, pre‐and postacclimation, respectively, n=3). Fractional and net glucose uptake in BAT increased 2.2‐fold (from 0.017±0.007 to 0.037±0.015 min−1 and from 81±35 to 183±82 nmol·g−1·min−1) following cold‐acclimation. Our preliminary results demonstrate an increased capacity of BAT‐derived thermogenesis during acute cold exposure after a 4‐week cold acclimation period in healthy men. This research was supported by the Natural Sciences and Engineering Research Council of Canada and the Canadian Diabetes Association (grant OG 3–10‐2970‐AC).