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Endocrinology, doi:10.1210/endo-102-5-1595
Endocrinology Vol. 102, No. 5 1595-1605
Copyright © 1978 by the Endocrine Society.
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Effect of Pregnant Mare's Serum Gonadotrophin on the Activities of {Delta}4-5{alpha}-Reductase, Aromatase, and Other Enzymes in the Ovaries of Immature Rats

KEIKO SUZUKI*, KAZUHIKO KAWAKURA{dagger} and BUN-ICHI TAMAOKI

National Institute of Radiological Sciences Anagawa-4-chome, Chiba-shi 280, Japan

Abstract

After incubation of progesterone, 17{alpha}hydroxyprogesterone, androstenedione, and testostrone with an ovarian preparation (supernatant fluid at 10,000 x g) of immature rats (21–23 days of age) in the presence of NADPH, 3{alpha}- and 3β-hydroxy-5{alpha}-reduced steroids were obtained as the major metabolites. Among the enzyme activities relevant to the metabolism, {dagger}4-5{alpha}reductase and 3β-hydroxysteroid dehydrogenase were intracellularly localized to the microsomal fraction (10,000-105,000 x g), and 3{alpha}-hydroxysteroid dehydrogenase was detected exclusively in the cytosol fraction (supernatant fluid at 105,000 x g).

Within 2 days after a single injection of pregnant mare's serum gonadotrophin (10 IU/rat) to 21-day-old female rats, the following occurred: 1) an enhancement of 17{alpha}-hydroxylase and C-17-C-20 lyase activities; 2) a suppression of {dagger}4-5{alpha}-reductase activity; and 3) an increase in aromatizing activity. From the above-mentioned results, it was concluded that the increased secretion of estrogen from ovaries of immature rats stimulated by pregnant mare's serum gonadotrophin administration was caused by a modification of the ovarian enzyme activities relevant to estrogen production. (Endocrinology 102: 1595, 1978)

Footnotes

* To whom requests for reprints should be addressed.

{dagger} Visiting scientist from the National Institute of Animal Industry, Aoba-cho, Chiba-shi 280.

Received June 27, 1977.




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M Bengtsson and J Rydstrom
Regulation of carcinogen metabolism in the rat ovary by the estrous cycle and gonadotropin
Science, March 25, 1983; 219(4591): 1437 - 1438.
[Abstract] [PDF]




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Copyright © 1978 by The Endocrine Society