Effects of finasteride and bicalutamide on prostatic blood flow in the rat

Objective To determine whether finasteride and bicalutamide, both currently used in the clinical management of patients with prostate diseases because they have anti-androgenic properties, have any effects on prostatic blood flow in a rat prostate model, as androgens are known to be involved in the regulation of prostatic blood flow and angiogenesis. Materials and methods Both finasteride and bicalutamide were supplied as oral suspensions in water and given daily to rats for 7 days by tube feeding. Blood flows to the ventral and dorsal prostates, and to the kidneys, were measured using the radioactive microsphere technique. In the bicalutamide experiments, some rats were treated with the Leydig cell toxin ethane dimethane sulphonate (EDS), to obtain a castration-like effect, and one group of these rats received testosterone. Results Finasteride induced a clear decrease in blood flow to the ventral and dorsal prostates after 7 days of treatment, with no significant changes in blood pressure or kidney blood flow. Bicalutamide inhibited the testosterone-induced increment of prostatic blood flow observed in EDS-treated animals. Conclusions Finasteride, a blocker of 5 alpha-reductase, decreases prostate blood flow after 7 days of administration. The response was slower than that after castration, but was of similar magnitude. Blood flow was also decreased after treatment with the androgen-receptor inhibitor bicalutamide. These observations suggest that prostatic blood flow is increased by dihydrotestosterone, and that the androgen receptor is responsible for mediating this effect.