Evidence for a non-androgenic role of testis and epididymis in androgen-supported growth of the rat ventral prostate.

A widely held view is that the role of testis in prostatic growth is through its ability to secrete androgen. Our earlier observation suggested a non-androgenic role for the testis, and perhaps the epididymis, in promoting growth of the ventral prostate in rats. The present study was conducted to evaluate the separate role of the testis and the epididymis in this phenomenon. In the first study, increasing quantities of silastic tubing filled with crystalline testosterone were implanted into adult Sprague-Dawley rats at the time of bilateral epididymo-orchiectomy or sham-operation. Twenty-eight days later, growth of the ventral prostate, as determined by fresh weight, DNA, and protein content, was significantly greater in sham-operated rats than in those receiving combined epididymo-orchiectomy, confirming our previous observation using dihydrotestosterone. In the second and third studies, rats were subjected to selective surgical procedures to evaluate the independent role of the testis and the epididymis. At the same time, 12 cm silastic tubing filled with testosterone or dihydrotestosterone were implanted subcutaneously into each of these animals for 28 days. Results indicated that the ventral prostate was significantly smaller in rats receiving the combined epididymo-orchiectomy than that of sham-operated controls. Simple orchiectomy or simple epididymectomy resulted in an increased weight of the ventral prostate between the two values obtained from the above two groups. Ligation of either the efferent duct or the vas deferens yielded ventral prostatic weights comparable to the androgen-treated, sham-operated controls. These results indicated that in order to achieve a maximal effect on androgen-supported growth of the ventral prostate, the presence of both the testis and the epididymis is required.