Non‐androgenic role of testis in enhancing ventral prostate growth in rats

Abstract

This study was conducted to investigate whether the testis, aside from its ability to secrete androgen, is able to promote prostatic growth in rats. Increasing quantities of silastic capsules filled with crystalline dihydrotestosterone (DHT) were implanted subcutaneously into adult Sprague-Dawley rats at the time of bilateral epididymo-orchiectomy or sham operation on the testes. Control animals received empty capsules. Twenty-eight days later, the growth of the ventral prostate as measured by wet weight, DNA, and protein content per prostate was significantly greater in rats with intact testes than in orchiectomized rats. An overall increased growth was noted at all doses of exogenous DHT administered. Serum levels of luteinizing hormone in animals treated with DHT were undetectable. Serum levels of testosterone in intact rats treated with DHT were not significantly different from those in castrated rats. These observations suggest a non-androgenic role for the testis and, perhaps, epididymis in promoting prostatic growth in rats, and are consistent with the concept that a non-androgenic substance, produced from the testis and/or epididymis, is able to enhance prostate growth induced by androgen stimulation. The possibility that this phenomenon may play a role in the benign growth of the prostate observed in aging human males with decreased blood levels of androgen warrants consideration.

Prostatic luminal cell differentiation and prostatic steroid‐binding protein (PBP) gene expression are differentially affected by neonatal castration

“…Nevertheless, our study provides further evidence to suggest that prostate growth must depend on additional factors other than androgen, both because androgen levels are relatively low during this period of development, and because androgen replacement alone did not allow for the proper onset of PBP expression. Our study supports those which have demonstrated that there is a nonandrogenic role for the testis in prostate growth [40][41][42][43].…”

Prostate innervation

“…To elucidate the interaction of the autonomic nervous system (ANS) and androgens in the growth of the rat prostate, we performed a unilateral ganglionectomy, but substituted supraphysiologic levels ofdihydrotestosterone (DHT) to promote maximal ventral prostate (VP) growth in an attempt to allow our surgical manipulations to have a greater effect [28]. As expected, the positive controls (no neural manipulation + DHT) showed marked hyperplasia of the ventral prostate (VP) (Fig.…”

Genes regulated by androgen in the rat ventral prostate

“…One major advantage of this choice is that the induction of androgen-response genes is not affected by other factor(s) or hormone(s) secreted from the testis. In contrast, castration may cause gene expression changes that are regulated by nonandrogen testicular factor(s) (39,40). Furthermore, the induction of androgen-response genes in the prostate by hormone replacement should be more rapid than that by castration because the decay of androgen after castration takes time.…”