Figure 1.

Adipose tissue functions in energy homeostasis and thermal regulation. (A) In humans, BAT localized around the shoulders and ribs contributes to heat generation. Brown adipocytes exhibit abundant mitochondria and UCP-1 expression related to thermogenesis. It has recently been speculated that BAT efficiency for fat-burning could be harnessed to reduce obesity. Visceral WAT (VAT) and subcutaneous WAT (SAT) possesses considerable capacities for energy storage. VAT surrounds intra-abdominal organs, whereas SAT spreads throughout the body beneath the skin. These fat tissues secrete various adipokines to regulate energy homeostasis. VAT is more strongly associated with obesity-induced metabolic disorders than SAT. (B) In adult mice, BAT is well developed and easily observed compared with that in adult humans. Among WAT depots within the abdominal cavity, the paired gonadal depots located around the ovaries in females and the testes in males are studied as a model of VAT. However, these depots do not exist in humans. The paired inguinal depots in the anterior to the upper part of the hind limbs are representative SATs in mice.