GPR120 controls neonatal brown adipose tissue thermogenic induction

Adaptive induction of thermogenesis in brown adipose tissue (BAT) is essential for the survival of mammals after birth. We herein show that G-coupled receptor protein-120 (GPR120) expression is dramatically induced after birth in mouse BAT. GPR120 expression in neonatal BAT is the highest among GPR120-expressing tissues in mouse at any developmental stage tested. The induction of GPR120 in neonatal BAT is caused by the postnatal thermal stress rather than by the initiation of suckling. GPR120-null neonates were found to be relatively intolerant to cold: close to one-third did not survive at 21ºC, but all such pups survived at 25ºC. Heat production in BAT was significantly impaired in GPR120-null pups. Deficiency in GPR120 did not modify brown adipocyte morphology or the anatomical architecture of BAT, as assessed by electron microscopy, but instead impaired the expression of UCP1 and the fatty acid oxidation capacity of neonatal BAT. Moreover, GPR120 deficiency impaired FGF21 gene expression in BAT and reduced plasma FGF21 levels. These results indicate that GPR120 is essential for neonatal adaptive thermogenesis through the control of the FGF21 system