Endocrinology, Vol 102, 1595-1605, Copyright © 1978 by Endocrine Society

ARTICLES

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

K Suzuki, K Kawakura and BI Tamaoki

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 3 beta-hydroxy-5 alpha-reduced steroids were obtained as the major metabolites. Among the enzyme activities relevant to the metabolism, delta 4-5 alpha-reductase and 3 beta-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 delta 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.

This article has been cited by other articles:

				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]