In vitro 19-norandrogen synthesis by equine placenta requires the participation of aromatase

摘要: Explants of equine full-term placenta have been shown to synthesize 19-norandrogens from labelled androgens. Steroid metabolites were purified by silica-gel column chromatography then analysed and quantified c18-reverse-phase HPLC coupled a radioactive flow detector. 19-Norandrostenedione was subsequently recrystallized constant specific activity, providing unequivocal evidence its synthesis the placenta. appeared be localized in microsomal fraction. Regardless substrate used, formation far weaker than that oestrogens; moreover, yield 17-oxosteroids produced much greater 17 beta-hydroxysteroids, suggesting presence dehydrogenase with predominant oxidative activity. Sulphoconjugated steroids formed less 0.5% total steroids. Although 19-nortestosterone could not generated aromatase incubated testosterone, oestrogens placental explants blocked two inhibitors, 4-hydroxyandrostenedione fadrozole. Our results provide for origin at least part previously identified blood pregnant mare. Furthermore, it is suggested 19-norandrogen biosynthesis would involve enzymatic metabolism 19-oxygenated androgens aromatase.