Divergent effects of prolactin on 4-ene-5 alpha-reductase activity and production of C19-steroids from progesterone in immature rat ovary.
Female rats of the Sprague-Dawley strain were used. Two pituitaries from 9-week old rats were grafted in both kidneys of 21-day old rat to induce hyperprolactinemia. All rats with or without pituitary isografts were hypophysectomized on day 26. Starting from day 29, the rats in groups of 8-11 were injected daily with 5 micrograms NIH-LH-S19 or saline for 3 days. Ovarian homogenates from these rats on day 32 were incubated with [14C]4-androstene-3,17-dione or [3H]progesterone and steroid metabolism was estimated. In the hypophysectomized rat ovary, the 5 alpha-reductase activity was stimulated significantly by LH. Although pituitary isograft alone had no stimulative effect on 5 alpha-reductase activity of the hypophysectomized rat ovary, concomitant treatment with LH and pituitary isograft (prolactin) had an additive effect. Formation of the sum of C19-steroids from progesterone in the hypophysectomized rat ovary was stimulated markedly by LH but reduced slightly by prolactin. The LH-induced production of C19-steroids from progesterone was inhibited markedly by prolactin. These results indicate that prolactin treatment inhibits basal and LH-induced production of C19-steroids from progesterone but stimulates LH-induced 4-ene-5 alpha-reductase activity in immature rat ovary.
D000728:Androgens / Q000096:biosynthesis / Q000302:isolation & purification; D000818:Animals; D005260:Female; D007016:Hypophysectomy; D007986:Luteinizing Hormone / Q000494:pharmacology; D010053:Ovary / Q000187:drug effects / Q000201:enzymology* / Q000254:growth & development; D010088:Oxidoreductases / Q000378:metabolism*; D044925:Oxidoreductases Acting on CH-CH Group Donors; D010902:Pituitary Gland / Q000637:transplantation; D011374:Progesterone / Q000378:metabolism*; D011388:Prolactin / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012741:Sexual Maturation; D013256:Steroids / Q000096:biosynthesis / Q000302:isolation & purification; D014599:Uterus / Q000254:growth & development
D000728:Androgens; D013256:Steroids; D011374:Progesterone; D011388:Prolactin; D007986:Luteinizing Hormone; D010088:Oxidoreductases; D044925:Oxidoreductases Acting on CH-CH Group Donors; C019940:cortisone alpha-reductase