PMA INHIBITS BOTH SPONTANEOUS AND GLUCOCORTICOID-MEDIATED LEPTIN SECRETION BY HUMAN OMENTAL ADIPOSE-TISSUE EXPLANTS IN-VITRO

The activation of PKC by the acute administration of the phorbol ester PMA (1 mu M, 2h) to omental adipose tissue explants in vitro resulted in a marked (about 75%) and persistent (up to at least 96 h) inhibiti on of leptin secretion. This PKC-mediated inhibition was not observed after the administration of an inactive phorbol ester (phorbol la,13-d icecanoate). The inhibition by PMA of leptin secretion was not restric ted to the spontaneous secretion, but blocked also effectively the lep tin response to a powerful stimulus, such as the glucocorticoid dexame thasone. As the PKC activity has been shown to be elevated during fast ing, the negative relation here described between PKC activity and lep tin secretion could be of physiological relevance. (C) 1998 Academic P ress.