Variations in adrenal androgen production among (nonhuman) primates

The synthesis and secretion of the adrenal androgens dehydroepiandrosterone (DHEA) and its sulfate (DS) is a phenomenon apparently unique to humans and nonhuman primates. It occurs at three life stages: in utero from the fetal zone (FZ) cells of the developing adrenal cortex, during adolescence with the onset of adrenarche and the development of the zona reticularis (ZR), and in ever decreasing amounts from the ZR with aging (adrenal senescence). Insufficient data exist to know if any single nonhuman primate exactly mirrors human adrenal androgen secretion through all three life stages, and detailed morphological, biochemical, and endocrinologic studies are required to do so. Androgen synthesis requires that cells express three key enzymes, 17alpha-hydroxylase/17,20-lyase cytochrome P450 (P450c17), nicotinamide-adenine dinucleotide phosphate (NADPH)-cytochrome P450 oxidoreductase (CPR), and cytochrome b5, and that they do not express 3beta-hydroxysteroid dehydrogenase (3beta-HSD). Cytochrome b5 has emerged as a particularly useful marker of androgen synthetic potential. Although a reliable index of the rate of adrenal androgen secretion, DS concentrations may not accurately reflect total adrenal androgen output because rates and routes of androgen metabolism may vary greatly among species. Based on the very limited available data, the most promising nonhuman primate models are marmosets for the human FZ, chimpanzees for human adrenarche, and macaques and baboons for mature ZR function that declines with senescence.