The inhibitory effect of β-adrenoceptor agonists on leptin expression in brown and white adipose tissues is now well documented both in vivo and in vitro. It suggests the existence in vivo of a retroregulatory loop by which leptin inhibits its own expression via the sympathetic nervous system and the β 3-adrenoceptor. The hypothesis that the defect in β 3-adrenoceptor described in the adipose tissue of hereditary obese rodents can contribute to the resistance to leptin and to the increase in leptin expression observed in these animals is discussed.