Adaptive thermogenesis and uncoupling proteins: a reappraisal of their roles in fat metabolism and energy balance.
After decades of controversies about the quantitative importance of autoregulatory adjustments in energy expenditure in weight regulation, there is now increasing recognition that even subtle variations in thermogenesis could, in dynamic systems and over the long term, be important in determining weight maintenance in some and obesity in others. The main challenge nowadays is to provide a mechanistic explanation for the role of adaptive thermogenesis in attenuating and correcting deviations of body weight and body composition, and in the identification of molecular mechanisms that constitute its effector systems. This workshop paper reconsiders what constitutes adaptive changes in thermogenesis and reassesses the role of the sympathetic nervous system (SNS) and uncoupling proteins (UCP1, UCP2, UCP3, UCP5/BMCP1) as the efferent and effector components of the classical one-control system for adaptive thermogenesis and fat oxidation. It then reviews the evidence suggesting that there are in fact two distinct control systems for adaptive thermogenesis, the biological significance of which is to satisfy--in a lifestyle of famine-and-feast--the needs to suppress thermogenesis for energy conservation during weight loss and weight recovery even under environmental stresses (e.g., cold, infection, nutrient imbalance) when sympathetic activation of thermogenesis has equally important survival value.
Dulloo
Abdul G
AG
Department of Medicine, Division of Physiology, University of Fribourg, Rue du Musée 5, CH-1700 Fribourg, Switzerland. abdul.dulloo@unifr.ch
Seydoux
Josiane
J
Jacquet
Jean
J
D000222:Adaptation, Physiological; D000818:Animals; D001823:Body Composition / Q000502:physiology; D001835:Body Weight / Q000502:physiology; D002352:Carrier Proteins / Q000378:metabolism*; D004734:Energy Metabolism / Q000502:physiology*; D005223:Fats / Q000378:metabolism*; D006801:Humans; D007473:Ion Channels; D008565:Membrane Proteins / Q000378:metabolism*; D024101:Mitochondrial Proteins; D008954:Models, Biological; D013564:Sympathetic Nervous System / Q000502:physiology; D022722:Thermogenesis / Q000502:physiology*; D000071256:Uncoupling Protein 1
D002352:Carrier Proteins; D005223:Fats; D007473:Ion Channels; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; C000604371:UCP1 protein, human; D000071256:Uncoupling Protein 1