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 isoform in this process. This study focused on the ARβ knockout mice (ARβKO), including responsiveness to cold exposure, diet-induced obesity, intolerance to glucose, dyslipidaemia and lipolysis in white adipose tissue (WAT). ARβKO 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, ARβKO 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 ARβKO animals when compared with WT controls. Isoproterenol-induced lipolysis in isolated white adipocytes as assessed by glycerol release was significantly impaired in ARβKO animals despite normal expression of key proteins involved in lipid metabolism. In conclusion, ARβ inactivation does not affect BAT thermogenesis but increases susceptibility to diet-induced obesity by dampening WAT lipolytic response to adrenergic stimulation.