Cold-induced thermogenesis is an energy-demanding process that protects warm-blooded animals against reductions in ambient temperature. Villanueva and colleagues demonstrated that in response to cold, the liver switches metabolism to provide acylcarnitines, which are used as fuel by brown fat. Exogenous L-carnitine also rescues the cold sensitivity seen with aging. Thus, this study uncovered an elegant mechanism whereby white adipose tissue provides long-chain fatty acids for hepatic carnitylation and generates plasma acylcarnitines that are used as a fuel source in peripheral tissues.
Global analysis of plasma lipids identifies liver-derived acylcarnitines as a fuel source for brown fat thermogenesis. Simcox J, Geoghegan G, Maschek JA, Bensard CL, Pasquali M, Miao R, Lee S, Jiang L, Huck I, Kershaw EE, Donato AJ, Apte U, Longo N, Rutter J, Schreiber R, Zechner R, Cox J, Villanueva CJ. Cell Metabolism. 2017 Sep;26(3):509.
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University of Utah Health: Boosting a Lipid Fuel Makes Mice Less Sensitive to the Cold.