In rodents, brown adipose tissue (BAT) regulates cold- (CIT) and diet-induced thermogenesis (DIT). Whether BAT recruitment is reversible and how it impacts on energy metabolism has not been investigated in humans. We examined the effects of temperature acclimation on BAT, energy balance and substrate metabolism in a prospective crossover study of 4-month duration, consisting of 4 consecutive blocks of 1-month overnight temperature acclimation [24°C (month 1) → 19°C (month 2) → 24°C (month 3) → 27°C (month 4)] of five healthy men in a temperature-controlled research facility. Sequential monthly acclimation modulated BAT reversibly, boosting and suppressing its abundance and activity in mild cold and warm conditions (p<0.05), respectively, independent of seasonal fluctuations (p<0.01). BAT-acclimation did not alter CIT but was accompanied by DIT (p<0.05) and post-prandial insulin sensitivity enhancement (p<0.05), evident only after cold-acclimation. Circulating and adipose tissue, but not skeletal muscle, expression levels of leptin and adiponectin displayed reciprocal changes concordant with cold-acclimated insulin sensitization. These results suggest regulatory links between BAT thermal plasticity and glucose metabolism in humans, opening avenues to harnessing BAT for metabolic benefits.
- Received March 31, 2014.
- Accepted June 8, 2014.
- © 2014 by the American Diabetes Association.
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