20 beta-hydroxysteroid dehydrogenase activity in nonflagellated germ cells of rainbow trout testis. (25/27)

Nonflagellated germ cells were isolated from rainbow trout testis to determine their ability to synthesize 17,20 beta-dihydroxy-4-pregnen-3-one (17,20 beta OHP), a progestin involved in the control of the release of sperm. Germ cells were obtained by enzymatic dissociation (collagenase; 3 mg.ml-1, 4.5 h, 12 degrees C) from testes that were immature and at the beginning of spermatogenesis. Somatic cells were eliminated by adhesion to the culture plates. Dose-related amounts of 17,20 beta OHP were measured by RIA in culture media of germ cells incubated with increasing dosages of 17-hydroxyprogesterone (17OHP; 0.05-10 micrograms.ml-1) for 20 h at 12 degrees C. Furthermore, 3H-17,20 beta OHP was identified by chromatography and co-crystallization with a reference in incubating cells provided by 3H-17OHP (2.5 and 4 h, 12 degrees C). Other metabolites were detected but not identified. 11-Ketotestosterone (11KT) was either nondetectable by RIA in control cultures or, when detected, was found at very low levels. In no case was 11KT stimulated by addition of 17OHP or gonadotropin II (GtH II; 400 ng.ml-1); this indicated the absence of contamination by Leydig cells. Thus, to our knowledge, this report demonstrates steroidogenic activities in nonflagellated germ cells of fish testis for the first time. 20 beta-Hydroxysteroid dehydrogenase (20 beta HSD) activity was identified, showing that germ cells are able to synthesize 17,20 beta OHP at an early stage in rainbow trout testis.  (+info)

20beta-hydroxysteroid dehydrogenase catalyzes ketone-reduction of acetohexamide, an oral antidiabetic drug, in liver microsomes of adult male rats. (26/27)

We examined the catalytic properties and physiological function of an enzyme responsible for the ketone-reduction of acetohexamide, an oral antidiabetic drug, in liver microsomes of adult male rats. Progesterone, 17alpha-hydroxyprogesterone, cortisone and cortisol, which have a ketone group at 20-position of C21-steroids, were potent inhibitors for ketone-reduction of acetohexamide in liver microsomes of adult male rats. Progesterone was also found to inhibit competitively the ketone-reduction of acetohexamide, suggesting that the ketone-reduction of acetohexamide and progesterone is catalyzed by the same enzyme. When progesterone was used as a substrate, 20beta-hydroxysteroid dehydrogenase present in liver microsomes of adult rats, such as acetohexamide reductase, exhibited a male-specific and androgen-dependent activity. Furthermore, a significant correlation was observed between the activities of 20beta-hydroxysteroid dehydrogenase and acetohexamide reductase in liver microsomes of individual male rats at various ages. Based on all results, we conclude that 20beta-hydroxysteroid dehydrogenase catalyzes the ketone-reduction of acetohexamide in liver microsomes of adult male rats.  (+info)

Histochemical studies of delta5-3beta-, 20lapha- and 20beta-hydroxysteroid dehydrogenases and possible progestagen production in hamster eggs. (27/27)

Hamster eggs at various developmental stages were studied histochemically fro the presence of delta5-3beta-hydroxysteroid dehydrogenase (HSD) (pregnenolone as the substrate and NAD as the cofactor), 20alpha-HSD (20alpha-hydroxypregn-4-en-3-one and NADP) and 20 beta-HSD (20beta-hydroxypregn-4-en-3-one and NAD). All three enzymes were absent from ovarian eggs but were demonstrated in unfertilized and fertilized eggs up to the blastocyst stage. The activities varied only slightly.  (+info)