PROBLEM: Several recent data suggest an involvement of endothelin (ET)-1, a
powerful vasoconstrictor peptide, in reproductive function. This study was
designed to investigate the presence and role of ET-1 in human corpus lute
um.
METHOD OF STUDY: Purified luteal cells were incubated for different times w
ith ET-1 or ET-3 alone or associated with human chorionic gonadotropin. In
another set of experiments cells were treated with ET-1 and BQ485, an ET-A
receptor antagonist, or with phorbol 12-myristate-13 acetate (PMA), an acti
vator of protein kinase C.
RESULTS: ET-1 reduced both basal and human chorionic gonadotropin-induced p
rogesterone production at all examined times, similarly PMA inhibited basal
progesterone synthesis. BQ485 prevented the inhibitory effect of ET-1, whi
le no effect was observed with ET-3. Finally, ET-1 mRNA was detected in the
luteal cells.
CONCLUSION: ET-1 is expressed by human luteal cells and reduces basal and h
uman chorionic gonadotropin-induced progesterone synthesis through the ET-A
receptors and the protein kinase C pathway. Conversely, ET-3 does not affe
ct luteal steroidogenesis.