Rapid reduction in blood flow to the rat ventral prostate gland after castration: Preliminary evidence that androgens influence prostate size by regulating blood flow to the prostate gland and prostatic endothelial cell survival

Abstract

BACKGROUND Androgenic steroids regulate the development and size of the mammalian prostate gland. The mechanism(s) for this growth control might involve a direct effect on prostate cell proliferation and survival as well as more complex effects on the tissue environment supporting nourishment and oxygenation. In this study, we evaluated an animal model of androgen action on the prostate, the rat ventral prostate gland, to determine whether acute androgen withdrawal, by means of castration, might alter the primary blood flow to the prostate gland and for the effects of castration on prostatic endothelial cell viability. METHODS Groups of rats studied included intact control males, males that had been surgically castrated, or males that received a sham‐surgical castration. Relative blood flow (RBF) to the rat ventral prostate glands and rat bladders were measured at 18 and 24 hr after castration or sham castration using a fluorescent microsphere infusion technique. Thin sections from fixed and embedded rat ventral prostate glands obtained from unoperated or 12‐hr castrated rats were analyzed by the TUNEL immunostaining technique to microscopically identify and quantify apoptotic epithelial, stromal, and endothelial cells. RESULTS RBF to the rat ventral prostate was reduced by 38% at 18 hr after castration when compared with intact or sham‐operated rats and by 45% at 24 hr after castration (P = 0.038 unoperated/0.025 sham operated). In contrast, RBF to the bladder was not significantly different between any of the groups in the 24‐hr castrate experiment. TUNEL staining analysis of ventral prostate tissues obtained from 12‐hr castrated rats showed only rare TUNEL‐positive epithelial cells similar to the control tissue but significantly increased TUNEL labeling for endothelial and other ventral prostate stromal cells. CONCLUSIONS Castration resulted in a rapid and significant reduction of blood flow to the mature rat ventral prostate gland that was not seen in the bladder. This reduction precedes the appearance of apoptosis in the epithelial cells of the tissue but more coincided with the appearance of TUNEL‐positive prostate vascular endothelial and stromal cells, suggesting that androgens support the survival of cells in the vascular and stromal compartment of the rat prostate as well as in the prostatic epithelium. These preliminary data support the concept that androgen action on the prostate might involve primary regulation of prostate blood flow and prostate vascular cell vitality. Prostate 36:201–206, 1998. © 1998 Wiley‐Liss, Inc.

Fibroblasts prolong serum prostate-specific antigen decline after androgen deprivation therapy in prostate cancer

“…Previous studies have reported that castration has a role in the reduction of blood flow in the rat ventral prostate gland. 30,31 The reduced number of blood vessels suggests that PSA levels in the circulation may have decreased because of the loss of secreted PSA entering the capillaries in the stroma. Godoy et al focused on paracrine signaling mediated through stromal or epithelial cells, and demonstrated the time course of changes in the vascular structure of tumors after ADT using a human prostate cancer primary xenograft model.…”

Physiological apoptosis in hormone-dependent tissues: involvement of caspases

“…57 Changes in the level of blood flow resulting in local hypoxia may also initiate epithelial cell apoptosis in the ventral prostate. 58,59 Following castration, blood flow in the prostate rapidly decreases, most likely due to endothelial cell apoptosis. 59 The resulting hypoxic conditions might be responsible for causing epithelial cell death.…”

Effect of short-term finasteride therapy on peroperative bleeding in patients who were candidates for transurethral resection of the prostate (TUR-P): a randomized controlled study

“…1 Blood loss is one of the most important causes of morbidity during TUR-P. 2 It has been previously demonstrated that androgen deprivation induces a marked involution of the vasculature in rat prostate and testosterone treatment rapidly reverses this process. [3][4][5] The effect of finasteride, which is a 5-alpha-reductase inhibitor, on prostatic bleeding due to BPH is well documented. It also decreases the incidence of surgery and acute retention besides limiting hematuria in patients with BPH.…”