Importance of catecholestrogens in the regulation of the ovarian cycle
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Using highly stabilized catecholestrogen preparations-ascorbic acid added to the free alcohols or benzoic acid derivatives — 2- and 4-hydroxyestrogens were tested in simple, clearly defined animal models: As index for the peripheral action the influence on vaginal opening and uterus weight gain was monitored after continuous s.c. administration for 6 days (minipumps) in immature intact rats resulting in a relative estrogenic potency (estradiol = 100%) of 70–100% for 4-hydroxyestradiol and less than 30% for 2-hydroxyestradiol. As index for the central action LH levels were measured in adult ovx rats leading to the same relations in the relative potencies. As index for both central and peripheral actions LH levels and the formation of corpora lutea were investigated in animals with an intact but prepubertal feed-back loop, i.e. in 25-day-old immature rats. 4-Hydroxyestradiol in this model clearly triggered LH surges and induced ovulations, its potency being in the same range as that of estradiol. 2-Hydroxyestradiol, in comparable doses, again showed no significant effect. Finally, female immature animals known to ovulate 3 days after PMS injection were treated concomitantly with either primary or catecholestrogen-antibody preparations. Whereas the primary estrogen antibody significantly blocked ovulation, the 2- and 4-hydroxyestrogen antibodies were ineffective. If, however, PMS and estrogen-antibody treated animals were supplemented with 4-hydroxyestrogens, ovulations could be restored. Thereby, it was inferred that peripheral 4-hydroxyestrogens, though not essential for the physiology of reproduction, can completely replace the physiologically essential peripheral estradiol at central target sites.
Key wordsOvarian cycle Physiology Catecholestrogens Rat
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- Ball P, Knuppen R (1980) Catecholestrogens (2- and 4-hydroxyestrogens): Chemistry, biogenesis, metabolism, occurrence and physiological significance. Acta Endocrinol [Suppl] (Copenh) 232: 1–128Google Scholar
- Ball P, Haupt M, Knuppen R (1978) Comparative studies on the metabolism of oestradiol in the brain, the pituitary and the liver of the rat. Acta Endocrinol (Copenh) 87: 1–11Google Scholar
- Ball P, Emons G, Gethmann U (1981a) Effect of low doses of continuously administered catecholoestrogens on peripheral and central target organs. Acta Endocrinol (Copenh) 96: 470–474Google Scholar
- Ball P, Schwarzlose C, Emons G (1982) Effects of antibodies to catecholoestrogens and catecholoestrogen-methyl ethers on PMS induced ovulations in immature rats. Acta Endocrinol (Copenh) 99: 443–447Google Scholar
- Emons G, Ball P (1981) Induction of ovulation in immature female rats by a single injection of 4-hydroxyoestradiol-benzoate. Acta Endocrinol (Copenh) 240: 101–102Google Scholar
- Emons G, Mente C, Knuppen R, Ball P (1981) Radioimmunoassay of 4-hydroxyoestrone in human urine. Acta Endocrinol (Copenh) 97: 251–257Google Scholar