Non-genomic effects of progesterone on the signaling function of G protein-coupled receptors

Progesterone at concentrations between 10 mu M and 200 mu M affected the ca lcium signaling evoked by ligand stimulation of G protein-coupled receptors expressed in several cell lines. At 160 mu M progesterone the signaling of all receptors,vas completely abolished. The effect of progesterone was fas t, reversible and was not prevented by cycloheximide indicating its non-gen omic nature. Overall, the action of progesterone was more cell type-specifi c than receptor-specific. Our results are in contrast to a recent report [G razzini, E., Guillon, G., Mouillac, B. and Zingg, H.H. (1998) Nature 392, 5 09-512] in which a direct high-affinity interaction between the oxytocin re ceptor and progesterone was suggested. (C) 1999 Federation of European Bioc hemical Societies.