Abstract Norandrogens are significant anabolic-androgenic steroids used initially for treatment of debilitating conditions, and later as performance-enhancing drugs. Regulatory challenges of their abuse in human, equine and canine sports stem from the question of endogenous norandrogens. Evidence from mass spectrometry for 19-norandrostenedione (19-norA4) in the sulfate fraction of conjugated steroids in equine yolk-sac fluid suggested a need for reexamination. In-vitro biosynthesis of 19-norandrogens was examined in highly purified preparations of porcine Leydig cells from mature pigs by incubation in medium containing 3H-androstenedione (A4) or nonradioactive A4. Steroids were recovered from media at solid-phase extraction, separately as unconjugated and conjugated fractions. Chromatographic (HPLC) profiles were obtained from solvent systems and liquid-scintillation counting (LSC) for radioactivity. Several peaks in the conjugated fractions were investigated further by HPLC. Two peaks widely separated on HPLC as conjugated steroids yielded evidence of 19-norA4 after solvolysis. Other peaks identified by HPLC retention times matching standards were 19-hydroxy-A4, A4 (substrate) and epiandrosterone. Incubations with non-radioactive A4 provided further evidence from radioimmunoassay for sulfated steroids as precursors of 19-norA4. With known high sulfotransferase activity in porcine Leydig cells, it is proposed that two 3-enol sulfates were formed as stable ‘precursors’ of 19-norA4 by the distinctive action of the third aromatase isoform of the boar testes. Although their identities remain unknown, it was shown that 19-norA4 itself was not present as a 3-enol sulfate. These findings have implications as endogenous anabolic agents in normal growth and with relevance to illegal use of anabolic androgens in sports and animal production.
Raeside et al. (Thu,) studied this question.