Studies on the Secretion and Interconversion of the Androgens. IV. Quantitative Results in a Normal Man Whose Gonadal and Adrenal Function Were Altered Experimentally1

The secretion of testosterone (T), 4-androstenedione (Δ), dehydroisoandrosterone (D) and dehydroisoandrosterone sulfate (DS) in a normal man was investigated using an experimental approach involving the simultaneous administration of 3 tracers, 1,2-3H-T, 4-14C-D and 7α-3H-DS. A model, consisting of 4 pools (corresponding to the 4 compounds), served to define the assumptions implicit in this approach. These assumptions and the possible influence of unaccounted for factors (e.g., other secretory products, or other metabolic pathways) upon the validity of the findings were analyzed in an accompanying paper. From the specific activities of various urinary metabolites obtained after the injection of the tracers, the rates of secretion, of production, of interconversion and of irreversible metabolism have been estimated for the 4 androgens. These rates were determined for 5 periods: under control conditions (period I), during adrenal stimulation (period II), during adrenal suppression (period III), during testicular stimulation while the adrenals were suppressed (period IV) and, finally, during testicular suppression (period V). The results show that androstenedione can be secreted by both the testes and the adrenals, whereas testosterone appears to be secreted only by the testes. Furthermore, during each period other than period III, the value obtained from the expression RT/āTG·t (frequently called the “production rate” of testosterone) was higher than its secretion rate. However, during period III, when the adrenals are suppressed, the secretory rate becomes equal to the production rate. The results also indicate that D is secreted not only by the adrenals but also by the testes. The secretion of D and DS is under the influence of ACTH and can be suppressed by dexamethasone.