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In Vitro Effects of Steroids upon the Production of Progesterone from Pregnenolone in the Human Corpus Luteum
Author(s) -
Sani Yumiko,
Okinaga Shoichi,
Arai Kiyoshi
Publication year - 1980
Publication title -
asia‐oceania journal of obstetrics and gynaecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.597
H-Index - 50
eISSN - 1447-0756
pISSN - 0389-2328
DOI - 10.1111/j.1447-0756.1980.tb00500.x
Subject(s) - pregnenolone , corpus luteum , androstenedione , medicine , endocrinology , estrone , testosterone (patch) , chemistry , steroid , dehydrogenase , in vitro , ovary , estrogen , enzyme , biology , hormone , biochemistry , androgen
Incubation of the 800 x g supernatant fluid of a human corpus luteum with 14 C‐pregnenolone produced progesterone. The inhibitory effects of various steroids on the production of progesterone were studied. Progesterone (Ki = 2.8 μ M), 17α‐hydroxy‐progesterone (1.6 μ M), estrone (0.24 μ M) and 17 β ‐estradiol (0.34 μ M) showed mixed type inhibition on the activity of Δ 5 ‐3 β ‐hydroxy‐steroid dehydrogenase and Δ 4 ‐Δ 5 isomerase (Km = 1.5 μ M). Androstenedione (Ki = 3.0 μ M) and testosterone (2.7 μ M) also inhibited the production of progesterone, but 16α‐hydroxy‐progesterone was less effective (Ki = 16 μ M). Among the synthetic estrogens tested, ethynylestradiol showed the highest inhibitory effect on the enzyme activity (Ki = 0.02 μ M).