[Beta 3 adrenergic receptor: physiologic role and potential therapeutic applications]

The characterization in 1989 of the gene encoding the beta 3-adrenoceptor helped to interpret the results of pharmacological experiments on atypical effects of catecholamines distinct from the classical activation of beta 1 and beta 2 adrenoceptors. In rodents, the beta 3 adrenoceptor is abundantly expressed in white adipose tissue where energy is stored in the form of triglycerides and in brown adipose tissue that is specialized for thermogenesis. Treatment of rodents with beta 3 adrenoceptor agonists induces a weight loss related to the stimulation of lipolysis in the two types of tissues. These results led to propose the use of these agonists for the treatment of human obesity and NIDDM. However, the poor lipolytic effect of these agonists in human adipose tissue and the recent discovery of functional beta 3 adrenoceptors in the human heart raise new questions on the therapeutic use of beta 3-adrenoceptor agonists in man. In the human ventricle, these agonists induce a negative inotropic effect. In vessels, stimulation of beta 3-adrenoceptors produces a vasodilation. If these effects are conserved in the failing heart, they could shed a new light on the pathogenic role of the hyperadrenergism associated with cardiac failure, as well as on its treatment with beta-adrenoceptor blockers.