title: In vitro metabolism of testosterone on hepatic tissue of chicken (Gallus domesticus).
abstract: Among the subcellular fractions of chicken liver homogenates, the microsomal and cytosol fractions were most active in metabolism of testosterone with mutually different enzymological features. On the other hand, the nuclear and mitochondrial fractions had far lower activity of metabolizing the steroid. Metabolism by the cytosol fraction: the following steroids were identified as the metabolites of testosterone. 5 beta-Dihydrotestosterone (17 beta-hydroxy-5 beta-androstan-3-one), 5 beta-androstane-3 alpha,17 beta-diol and its 3 beta-epimer, 3 alpha-hydroxy-5 beta-androstan-17-one and its 3 beta-epimer and 5 beta-androstanedione. Metabolism by the microsomal fraction: from testosterone under aerobic condition, androstenedione was obtained as the major metabolite, besides the minor polar metabolites, production of which diminished when incubated in the atmosphere of carbon monoxide. From the results, testosterone was accepted to be firstly converted by the cytosol fraction into 5 beta-dihydrotestosterone which was then reduced to 5 beta-androstane-3 alpha,17 beta-diol and its 3 beta-epimer. These diols were further converted partially to 3 alpha -and 3 beta-hydroxy-5 beta-androstan-17-ones. These pathways were supported by the results of our incubation study with 5 beta-dihydrotestosterone and 5 beta-androstanedione as substrates. By the microsomes, testosterone was aerobically and anaerobically transformed to androstenedione as the major metabolite. Throughout our incubation experiments, no 5 alpha-reduction of a delta 4-3-oxo-steroid was detected in the chicken liver.
authors.affiliation: Department of Radiopharmacology, Faculty of Pharmaceutical Sciences, Nagasaki University, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Sugimoto
authors.forename: Y
authors.initials: Y
authors.lastname: Ohta
authors.forename: T
authors.initials: T
authors.lastname: Morikawa
authors.forename: T
authors.initials: T
authors.lastname: Yamashita
authors.forename: M
authors.initials: M
authors.lastname: Yoshida
authors.forename: B
authors.initials: B
authors.lastname: Tamaoki
mesh_terms: D000818:Animals; D001345:Autoradiography; D002645:Chickens; D002855:Chromatography, Thin Layer; D008099:Liver / Q000378:metabolism*; D013058:Mass Spectrometry; D008862:Microsomes, Liver / Q000378:metabolism; D013739:Testosterone / Q000378:metabolism*
chemical_list: D013739:Testosterone