BROWN ADIPOSE-TISSUE, BETA-3-ADRENERGIC RECEPTORS, AND OBESITY

Brown adipose tissue is distinguished by its unique capacity for uncou pled mitochondrial respiration, which is highly regulated by sympathet ic nerve activity. Because of this, energy expenditure in brown fat is capable of ranging over many orders of magnitude. The fact that the f unction of brown adipose tissue is impaired in obese rodents and that transgenic mice with decreased brown fat develop obesity demonstrates the importance of brown fat in maintaining nutritional homeostasis. Ho wever, the role of brown fat in humans is less clear. beta 3-Adrenergi c receptors are found on brown adipocytes, and treatment with beta 3-s elective agonists markedly increases energy expenditure and decreases obesity in rodents. Whether beta 3-selective agonists will be effectiv e anti-obesity agents in humans is presently under investigation.