title: Enhanced dehydroepiandrosterone synthesis by amnion compared to chorion: a comparative study using the reverse-isotope dilution technique.
abstract: With a view to establishing whether the term human fetal membranes possess the enzymic ability to synthesize dehydroepiandrosterone (DHEA) from pregnenolone, homogenates of amnion and chorion obtained from women (n = 5, age 27-34 years) after spontaneous labor at term (37-42 weeks gestation) from uncomplicated pregnancies were incubated with [7n-3H]pregnenolone as substrate. Reverse-isotope dilution analysis gave positive identification of [3H]DHEA acetate in all incubations of viable tissues. No such metabolite was evident in control incubations with heat-denatured tissues. Virtually radiochemically pure esters under three recrystallizations were obtained with mean concentrations of between 15787 and 30137 dpm mol(-1) for amnion which was considerably higher than that of chorionic tissues at 4316-5528 dpm mol(-1). The magnitude of elevation in DHEA production by amnion was noted to be between 3.6- and 5.5-fold higher than the corresponding chorion. This study provides evidence that the fetal membranes possess 17-alpha hydroxylase and C-17, 20 lyase activities capable of synthesis of DHEA, an important androgen necessary for aromatization to estrogens in need by the developing fetus.
authors.affiliation: University Department of Obstetrics & Gynaecology, National University Hospital, Singapore.
authors.forename: A
authors.initials: A
authors.lastname: Loganath
authors.forename: K L
authors.initials: KL
authors.lastname: Peh
authors.forename: Y C
authors.initials: YC
authors.lastname: Wong
authors.forename: S C
authors.initials: SC
authors.lastname: Ng
mesh_terms: D000650:Amnion / Q000201:enzymology / Q000378:metabolism*; D002823:Chorion / Q000201:enzymology / Q000378:metabolism*; D003460:Crystallization; D003687:Dehydroepiandrosterone / Q000096:biosynthesis*; D005260:Female; D006801:Humans; D010920:Placenta / Q000737:chemistry; D011247:Pregnancy; D011284:Pregnenolone / Q000737:chemistry / Q000378:metabolism; D011865:Radioisotope Dilution Technique; D014020:Tissue Extracts / Q000737:chemistry; D014316:Tritium / Q000737:chemistry / Q000378:metabolism
chemical_list: D014020:Tissue Extracts; D014316:Tritium; D003687:Dehydroepiandrosterone; D011284:Pregnenolone