A. Zosmer et al., 2ND MESSENGERS AND THE CONTROL OF PROGESTERONE PRODUCTION FROM FIRST-TRIMESTER TROPHOBLAST, Journal of steroid biochemistry and molecular biology, 62(2-3), 1997, pp. 201-205
Basal progesterone production from first trimester placental cells in
culture was high during the first 24 h of culture and fell to less tha
n 30% of the initial level after 96 h in vitro. 22(R)-Hydroxycholester
ol had a similar effect on progesterone production at all incubation t
imes, indicating that the decline in basal steroidogenesis was not due
to a loss of mitochondrial or post-mitochondrial enzymes. Continuous
stimulation with dibutyryl (db) cyclic AMP maintained progesterone syn
thesis at a relatively constant high level despite the fall in basal p
rogesterone production, and the optimum concentration of db cyclic AMP
was 1.0 mM. The calcium ionophore A23187 had no effect on progesteron
e incubation during short-term cultures (<4 h), and inhibited steroido
genesis after 24 h. Repeated addition of A23187 during 96 h of culture
also inhibited progesterone production. These findings indicate that
progesterone production in human trophoblast is supported by a local f
actor which maintains a high level of steroid production through a cyc
lic AMP-dependent mechanism. The inhibitory effects of calcium ionopho
re in trophoblast differ from the stimulatory effects of this compound
in other steroidogenic cells, but the reasons for the difference are
not known at present. (C) 1997 Elsevier Science Ltd.