UC Davis

The androgen precursors, dehydroepiandrosterone (DHEA) and DHEA sulfate (DHEAS) are produced in high amounts by the adrenal cortex primarily in humans and a few other primates. The human adrenal also secretes 11-oxygenated androgens (11-oxyandrogens), including 11β-hydroxyandrostenedione (11OHA4), 11-ketoandrostenedione (11KA4), 11β-hydroxytestosterone (11OHT) and 11-ketotestosterone (11KT), of which 11OHT and 11KT are bioactive androgens. The 11-oxyandrogens, particularly 11KT, have been recognized as biologically important testicular androgens in teleost fishes for decades, but their physiological contribution in humans has only recently been established. Beyond fish and humans, however, the presence of 11-oxyandrogens in other species has not been investigated. This study provides a comprehensive analysis of a set of C₁₉ steroids, including the traditional androgens and 11-oxyandrogens, across 18 animal species. As previously shown, serum DHEA and DHEAS were much higher in primates than all other species. Circulating 11-oxyandrogens, especially 11KT, were observed in notable amounts in male, but not in female trout, consistent with gonadal origin in fish. The circulating concentrations of 11-oxyandrogens ranged from 0.1 to 10 nM in pigs, guinea pigs and in all the primates studied (rhesus macaque, baboon, chimpanzee and human) but not in rats or mice, and 11OHA4 was consistently the most abundant. In contrast to fish, serum 11KT concentrations were similar in male and female primates for each species, despite significantly higher circulating testosterone in males, suggesting that 11KT production in these species is not testis-dependent and primarily originates from adrenal-derived 11-oxyandrogen precursors.