Initiation of Human Parturition. VI. Identification and Quantification of Progesterone Metabolites Produced by the Components of Human Fetal Membranes

Abstract

The fetal membranes play a central role in the initiation of human parturition, a role that may be subserved in part by quantitative changes in progesterone metabolism. In order to identify and to quantify the metabolites of progesterone produced by die components of the human fetal membranes, amnion and chorion laeve tissues and homogenateswere incubated with [³H]progesterone in the presence of added NADPH. The radioactive metabolites, 20α-hydroxy-4-pregnen-3-one, 5α-pregnane- 3,20-dione and 3β-hydroxy-5α-pregnan-20-one, were isolated and identified by derivative formation, a combination of chromatographie techniques, and by crystallization to constant specific activity after addition of authentic standards. A simplified technique of metabolite quantification was developed that involves one thin layer chromatographie procedure and liquid scintillation assay of radioactivity. The accuracy of this method was established by comparison with data obtained using classical techniques. This study demonstrates the presence of human fetal membranes 5α-reductase, 20α-hydroxysteroid oxidoreductase, and 3β-hydroxy-steroid oxidoreductase, and a qualitative difference betweenamnion and chorion laeve.