Aging and tissue androgens.

Testosterone, 5 alpha-androstane-17 beta-ol-3-one (DHT) and 5 alpha-androstane-3 alpha,17 beta-diol (Adiol) concentrations were measured in postmortem tissues (pubic skin, scrotal skin, thigh skin, and striated muscle) from 24 males, aged 20-82 yr. Androgen concentrations were highest in scrotal skin, followed by those in pubic skin, and lowest in thigh skin and striated muscle. Moreover, using the ratio of DHT plus Adiol over testosterone as a parameter of 5 alpha-reductase activity, the following order, from highest to lowest activity, was found: scrotal skin greater than pubic skin greater than thigh skin greater than striated muscle. If the Adiol over DHT ratio was taken as a parameter of 3-reductase activity, then this order, from highest to lowest activity, was: striated muscle greater than thigh skin greater than pubic skin greater than scrotal skin. An age-dependent decrease in androgen concentration was only found in pubic skin. The unexpected absence of such a decrease in scrotal skin might be explained by the embryological origin of the scrotum, which is similar to that of the prostate, an organ which also does not show any age-dependent decrease in androgen concentration. In the other tissues, this absence might be related to the relatively low concentration, high individual variability, and small number of subjects studied.