control of brown adipose tissue glucose and lipid metabolism by pparγ

Brown adipose tissue (BAT) non-shivering thermogenesis impacts energy homeostasis in rodents and humans. Mitochondrial UCP1 in brown fat cells produce heat by dissipating the energy generated by the oxidation of fatty acids and glucose. In addition to thermogenesis and despite its small relative size, sympathetically activated BAT constitutes an important glucose, fatty acid and triacylglycerol-clearing organ, and such function could potentially be used to alleviate dyslipidemias, hyperglycemia and insulin resistance. To date, chronic sympathetic innervation and PPARγ activation are the only recognized inducers of BAT recruitment. Here, we review the major differences between these two inducers of BAT recruitment in the regulation of lipolysis, fatty acid oxidation, lipid uptake and triacylglycerol synthesis, glucose uptake and de novo lipogenesis. Whereas BAT recruitment through sympathetic drive translates into functional thermogenic activity, PPARγ-mediated recruitment is associated with a reduction in sympathetic activity leading to increased lipid storage in brown adipocytes. The promising therapeutic role of brown adipose tissue in the treatment of hypertriglyceridemic and hyperglycaemic conditions are also discussed.