Synergism between insulin and low concentrations of isoproterenol in the stimulation of leptin release by cultured human adipose tissue

The release of leptin by pieces of human adipose tissue incubated in primar y culture for 24 or 48 hours in the presence of dexamethasone was reduced b y isoproterenol. An inhibition of leptin release was observed at 24 hours i n the presence of isoproterenol and was mediated by beta(1)-adrenergic rece ptors, since it was blocked by the specific beta(1)-adrenoceptor antagonist CGP-20712A. The inhibitory effect of 33 nmol/L isoproterenol on leptin rel ease was reversed in the presence of 0.1 nmol/L insulin to a 2-fold stimula tion of leptin release. These data suggest that the primary mechanism by wh ich insulin stimulates leptin release is to blunt the inhibitory effects of beta(1)-adrenergic receptor agonists, and low concentrations of catecholam ines actually enhance the stimulation of leptin release by insulin. Copyrig ht (C) 2000 by W.B. Saunders Company.