title: Inhibition by a 4-methyl-4-aza-steroid of NADPH: delta 4-3-oxosteroid-5 alpha-oxido-reductase activity in cultured interstitial cells derived from immature rat testis.
abstract: Prepubertal rat testes have high 5 alpha-reductase (delta 4-3-oxosteroid 5 alpha-oxidoreductase) activity and secrete various 5 alpha-reduced androgens. We demonstrate that Na-4-methyl-4-aza-3-oxo-5 alpha-pregnane-20 (S)-carboxylate, a potent inhibitor of the prostatic 5 alpha-reductase, competitively inhibits the microsomal 5 alpha-reductase of rat testis. The apparent Ki for testosterone is 3.5 nM. At a concentration of 5 X 10(-7) M this compound efficiently inhibits the 5 alpha-reductase in cultured interstitial cells derived from prepubertal rats. Testosterone and 4-androstene-3,17-dione are the major androgens produced by these cells in the presence of inhibitor. It is concluded that 4-methyl-4-aza-steroids are a useful tool in the study of steroid secretion by prepubertal Leydig cells.
mesh_terms: D058891:5-alpha Reductase Inhibitors; D000818:Animals; D001378:Azasteroids / Q000494:pharmacology*; D002478:Cells, Cultured; D007700:Kinetics; D008297:Male; D008861:Microsomes / Q000201:enzymology*; D010088:Oxidoreductases / Q000037:antagonists & inhibitors*; D011278:Pregnanes / Q000494:pharmacology*; D051381:Rats; D012741:Sexual Maturation; D013260:Steroids, Heterocyclic / Q000494:pharmacology*; D013737:Testis / Q000201:enzymology*
chemical_list: D058891:5-alpha Reductase Inhibitors; D001378:Azasteroids; D011278:Pregnanes; D013260:Steroids, Heterocyclic; C037399:4-methyl-4-aza-3-oxopregnane-20-carboxylate; D010088:Oxidoreductases