title: Identification of phospholipids capable of modulating the activities of some enzymes involved in androgen and 16-androstene biosynthesis in the immature pig testis.
abstract: Testicular steroidogenic enzymes in the microsomal fraction from immature pigs were investigated for the effects of phospholipids of known structure on androgen and 16-androstene biosynthesis. Untreated (control) microsomes metabolized pregnenolone to 17-hydroxypregnenolone, DHA and small quantities of progesterone, 17-hydroxyprogesterone, androstenedione and testosterone; and to 5,16-androstadien-3 beta-ol (andien-beta) and 4,16-androstadienone (dienone) in the 16-androstene pathway. Phosphatidyl(P)-serine, P-glycerol, P-ethanolamine, P-inositol, P-choline and phosphatidic acid did not significantly alter the 17-hydroxylase/C-17,20 lyase or "andien-beta-synthetase" activities. Thus, the C21 side-chain cleavage reactions appeared not to be dependent upon phospholipids for optimal activity. The conversion of pregnenolone to 4-ene steroids (progesterone, 17-hydroxyprogesterone, androstenedione and testosterone) was inhibited by dilinoleoyl-phosphatidyl-choline, but other phospholipids tested were without effect. On the other hand, the conversion of andien-beta to dienone was inhibited by P-serine, P-inositol and P-cholines with short saturated or long polyunsaturated acyl chains. Therefore, the presence of these phospholipids in pregnenolone incubations had different consequences for 3 beta-hydroxysteroid dehydrogenase-isomerase activities. It is concluded that substrate specific 3 beta-HSD-isomerases exist for androgen and 16-androstene biosynthesis and that phospholipids may play an intrinsic role in their catalytic activity.
authors.affiliation: Centre de Recherche en Reproduction Animale (C.R.R.A.), Department d'Anatomie et Physiologie Animale, Faculté de Médecine Vétérinaire, Université de Montréal, St-Hyacinthe, Québec, Canada.
authors.forename: G M
authors.initials: GM
authors.lastname: Cooke
mesh_terms: D015096:3-Hydroxysteroid Dehydrogenases / Q000378:metabolism*; D000446:Aldehyde-Lyases / Q000378:metabolism*; D000728:Androgens / Q000096:biosynthesis*; D000736:Androstenes / Q000378:metabolism*; D000818:Animals; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D008297:Male; D008861:Microsomes / Q000201:enzymology / Q000378:metabolism; D010088:Oxidoreductases / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism* / Q000502:physiology; D011284:Pregnenolone / Q000378:metabolism; D013254:Steroid 17-alpha-Hydroxylase / Q000378:metabolism*; D013552:Swine; D013737:Testis / Q000201:enzymology / Q000378:metabolism*
chemical_list: D000728:Androgens; D000736:Androstenes; D010743:Phospholipids; C042468:16-androstene; D011284:Pregnenolone; D003577:Cytochrome P-450 Enzyme System; D010088:Oxidoreductases; C019701:androsta-5,16-dien-3 beta-ol synthetase; D015096:3-Hydroxysteroid Dehydrogenases; D013254:Steroid 17-alpha-Hydroxylase; D000446:Aldehyde-Lyases