Metabolism of pregnenolone-4-14C by the testis of Gobius paganellus (Teleostei)☆☆☆

Abstract The steroid-synthetic capacity of the mature testis of the teleost Gobius paganellus was studied in vitro by incubating the tissue with pregnenolone-4- 14 C of four different specific activities for four different time intervals. Metabolic products were identified by their mobilities on thin-layer chromatograms, derivative formation, radio-gas chromatography, and recrystallization to constant specific activity. Both free and conjugated metabolites appeared in the incubates. Among the free metabolites, formation of C 19 steroids was observed and two different biosynthetic pathways were suggested by the kinetics of the product yield-time curves: (1) pregnenolone → progesterone → 17α-OH-progesterone → androstenedione → testosterone and (2) pregnenolone → 17α-OH-pregnenolone → dehydroepiandrosterone, the former pathway being predominant. Many polar metabolites and other unknown compounds were also detected but not identified. Conjugation of unidentified products as β-glucuronosides and “sulfate” esters is also reported. These metabolic features are discussed in comparison with those reported for higher vertebrates.