Metabolism of androgens by the active and inactive prostate gland, and the seasonal changes in systemic androgen levels in the grey squirrel (Sciurus carolinensis Gmelin).

Abstract

The nuclear and cytoplasmic fractions derived from the actively secretory and inactive prostate of adult grey squirrels were incubated with radioactive testosterone and androstenedione. Testosterone was metabolized first to 5 alpha-dihydrotestosterone and then 5 alpha-androstane-3 alpha(beta), 17 beta-diols. Testosterone could also be transformed into androstenedione and then to androsterone, but no 5 alpha-dihydrotestosterone or diols could be synthesized from this pathway. Neither subcellular fraction of the inactive, non-secretory prostate could produce 5 alpha-androstane-3 alpha(beta), 17 beta-diols from testosterone either in the absence or presence of exogenous NADPH. The synthesis of androstenedione and 5 alpha-dihydrotestosterone by the nuclear and cytoplasmic fractions of the inactive gland were significantly increased compared to that in fractions of the active prostate. The increase was unaffected by exogenous NADPH. The concentration of androgen (testosterone plus 5 alpha-dihydrotestosterone) in systemic plasma was highest in December, the beginning of the breeding season. For the remainder of the breeding season, the androgen level was similar to that found in the non-breeding season. It is suggested that formation of 5 alpha-androstane-3 alpha(beta), 17 beta-diols was associated with the secretory activity of the prostate. The failure of the inactive prostate to synthesize these diols during sexual quiescence might be a means of ensuring the inactivity of the prostate.