Evidence for a Role for Adenosine 3′,5′-Monophosphate in Progesterone Secretion by Human Chorion*

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Abstract
Experiments were performed to determine whether cells from human chorion can synthesize and release progesterone. Cells were isolated from term chorion leave by collagenase-DNase digestion and incubated in RPMI-1640 medium. Freshly isolated cells contained 9.9 .+-. 1.1 ng progesterone/106 cells, and released 72.0 .+-. 7.1 ng/106 cells .cntdot. 24 h in the absence of precursors. When 25-hydroxycholesterol (25HC) served as a precursor, progesterone release into the medium was concentration and time dependent from 1-20 .mu.g/ml up to 8 h. When pregnenolone served as a precursor, progesterone secretion followed Michaelis-Menten kinetics (Km = 6.7 .mu.M: Vmax 1.02 nmol/106 cells .cntdot. h). In the presence of 25HC (20 .mu.g/ml), progesterone release increased significantly on exposure to cholera toxin (1 .mu.g/ml), methylisobutylxanthine (0.1 mM). Forskolin (0.1 mM), or (Bu)2cAMP (1 mM). Cells maintained in culture released progesterone when fetal calf serum (10%) or 25HC served as precursors. Apparently, trophoblasts from fetal membranes can synthesize and release progesterone from endogenous and exogenous precursors and support the suggestion that cAMP is an important mediator in this process.