Anatomical localization, gene expression profiling and functional characterization of adult human neck brown fat

The imbalance between energy intake and expenditure is the underlying cause of the current obesity and diabetes pandemics. Central to these pathologies is the fat depot: white adipose tissue (WAT) stores excess calories, and brown adipose tissue (BAT) consumes fuel for thermogenesis using tissue-specific uncoupling protein 1 (UCP1)(1,2). BAT was once thought to have a functional role in rodents and human infants only, but it has been recently shown that in response to mild cold exposure, adult human BAT consumes more glucose per gram than any other tissue(3). In addition to this nonshivering thermogenesis, human BAT may also combat weight gain by becoming more active in the setting of increased whole-body energy intake(4-7). This phenomenon of BAT-mediated diet-induced thermogenesis has been observed in rodents(8) and suggests that activation of human BAT could be used as a safe treatment for obesity and metabolic dysregulation(9). In this study, we isolated anatomically defined neck fat from adult human volunteers and compared its gene expression, differentiation capacity and basal oxygen consumption to different mouse adipose depots. Although the properties of human neck fat vary substantially between individuals, some human samples share many similarities with classical, also called constitutive, rodent BAT.