UCP1 and obesity due to melanocortin 4 receptor deficiency: β3-Adrenoceptors are expressed primarily in BAT [53], and chronic systemic infusion of a β3-adrenoceptor agonist in rats of high-fat diet-induced obesity increases body core temperature, energy expenditure and UCP1 content in BAT, and reduces the weights of white adipose tissue depots without altering food intake, ameliorating the obesity [20].