Thyroid hormone activates thermogenesis in brown and white adipose tissues through both central sympathetic nervous system pathways and direct peripheral effects on Ucp1 expression.
This review summarizes the central and peripheral mechanisms by which thyroid hormone regulates thermogenesis in adipose tissues.
Thermogenesis is the production of heat that occurs in all warm-blooded animals. During cold exposure, there is obligatory thermogenesis derived from body metabolism as well as adaptive thermogenesis through shivering and non-shivering mechanisms. The latter mainly occurs in brown adipose tissue (BAT) and muscle; however, white adipose tissue (WAT) also can undergo browning via adrenergic stimulation to acquire thermogenic potential. Thyroid hormone (TH) also exerts profound effects on thermoregulation, as decreased body temperature and increased body temperature occur during hypothyroidism and hyperthyroidism, respectively. We have termed the TH-mediated thermogenesis under thermoneutral conditions "activated" thermogenesis. TH acts on the brown and/or white adipose tissues to induce uncoupled respiration through the induction of the uncoupling protein (Ucp1) to generate heat. TH acts centrally to activate the BAT and browning through the sympathetic nervous system. However, recent studies also show that TH acts peripherally on the BAT to directly stimulate Ucp1 expression and thermogenesis through an autophagy-dependent mechanism. Additionally, THs can exert Ucp1-independent effects on thermogenesis, most likely through activation of exothermic metabolic pathways. This review summarizes thermogenic effects of THs on adipose tissues.
Yau et al. (Fri,) conducted a review in Thermogenesis and thyroid hormone effects. Thyroid hormone was evaluated. Thyroid hormone activates thermogenesis in brown and white adipose tissues through both central sympathetic nervous system pathways and direct peripheral effects on Ucp1 expression.