Disruption of beta3 adrenergic receptor increases susceptibility to DIO in mouse

The brown adipose tissue (BAT) mediates adaptive changes in metabolic rate by responding to the sympathetic nervous system through β-adrenergic receptors (AR). Here, we wished to define the role played by the ARβ 3 isoform in this process. This study focused on the ARβ 3 knockout mice (ARβ 3 KO), including responsiveness to cold exposure, diet-induced obesity, intolerance to glucose, dyslipidaemia and lipolysis in white adipose tissue (WAT). ARβ 3 KO mice defend core temperature during cold exposure (4°C for 5 h), with faster BAT thermal response to norepinephrine (NE) infusion when compared with wild-type (WT) mice. Despite normal BAT thermogenesis, ARβ 3 KO mice kept on a high-fat diet (HFD; 40% fat) for 8 weeks exhibited greater susceptibility to diet-induced obesity, markedly increased epididymal adipocyte area with clear signs of inflammation. The HFD-induced glucose intolerance was similar in both groups but serum hypertriglyceridemia and hypercholesterolemia were less intense in ARβ 3 KO animals when compared with WT controls. Isoproterenol-induced lipolysis in isolated white adipocytes as assessed by glycerol release was significantly impaired in ARβ 3 KO animals despite normal expression of key proteins involved in lipid metabolism. In conclusion, ARβ 3 inactivation does not affect BAT thermogenesis but increases susceptibility to diet-induced obesity by dampening WAT lipolytic response to adrenergic stimulation.