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Inhibition of the Pregnenolone <i>Δ</i><sup>5</sup>–3β-Hydroxysteroid Dehydrogenase-<i>Δ</i><sup>5-</sup><sup>4</sup> Isomerase Systems of Human Placenta and Corpus Luteum of Pregnancy
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References
1973
Year
Corpus LuteumGynecologyFemale Reproductive FunctionEmbryologyReproductive EndocrinologyMolecular PharmacologyMedicinal ChemistryReproductive MedicinePublic HealthSteroid MetabolismPlacental DevelopmentReproductive HormoneHuman PlacentaBiochemistryIsomerase SystemsMaternal HealthPlacental DiseaseAromataseMaternal-fetal MedicineEndocrinologyPharmacologyPlacental FunctionDevelopmental BiologyPregnancyM Estradiol-17MedicineEndocrine ResearchDrug Discovery
The inhibition of the pregnenolone <i>&#916;</i><sup>5</sup>–3&#914;-hydroxysteroid dehydrogenase-&#916;<sup>5-4</sup> isomerase systems in microsomes of human placenta or corpus luteum of pregnancy has been investigated using three steroidal substances: 2&#913;-cyano- 4,4,17&#914;-trimethylandrost-5-en-17&#913;-ol-3-one (cyanoketone), 2- hydroxymethylene, 17&#913;-methyl-5&#913;-androstan-17&#914;-ol-3-one (oxymetholone), and estradiol 17&#914;. The inhibition is of the competitive type with the synthetic steroids. The apparent K<sub>i</sub>&#8217;s are approximately 0.3xl0<sup>-5</sup> M and 0.2xI0<sup>-5</sup> m for cyanoketone in the placental and ovarian systems, respectively, and the apparent K<sub>i</sub> produced by oxymetholone is 0.6x10<sup>-6</sup> m in the ovarian system, however, that for the placental system is much smaller, 5.5xl0<sup>-8</sup> M. Approximately 50% inhibition was obtained in both systems with 2–5xl0<sup>-5</sup> M estradiol-17&#914;. Oxymetholone may be useful for the inhibition of corpora luteal function in women.