A Dual 5α-Reductase Inhibitor Dutasteride Caused Reductions in Vascular Density and Area in Benign Prostatic Hyperplasia

Objectives. Dutasteride, a dual 5α-reductase inhibitor, is used to treat benign prostatic hyperplasia. Nevertheless, its histopathological effects on the morphometrics of blood vessels and glands are still controversial. The aim here was to assess the histopathological effects of dutasteride in cases of benign prostatic hyperplasia in a retrospective study. Methods. Patients with benign prostatic hyperplasia more than 40？cm3 in prostatic volume were administered 0.5？mg of dutasteride daily or left untreated prior to receiving a transurethral resection of the prostate. Images of sections stained with hematoxylin/eosin and with anti-CD31 antibody were analyzed. Results. In the dutasteride-treated group, the duration of administration was weeks. Artery/arteriole density and vein/venule density in benign prostatic tissue were both lower in the dutasteride-treated group than in the control group. The vein/venule area as a percentage of the whole area was also lower in the dutasteride-treated group, while the artery/arteriole area did not show a significant difference. Glandular/CD31-expressing vessel densities as well as glandular/CD31-expressing vessel areas were comparable between the two groups. Conclusions. Dutasteride reduced the artery/arteriole and vein/venule densities and the proportion of vein/venule area in the tissue of patients with benign prostatic hyperplasia. 1. Introduction Benign prostatic hyperplasia (BPH) is a histologic diagnosis that refers to the proliferation of smooth muscle and epithelial cells within the prostatic transition zone, for which dihydrotestosterone (DHT) is the primary androgen responsible in elderly men [1]. As the initial treatment for symptomatic BPH, pharmacotherapy with -adrenergic blockers, -reductase inhibitors, antimuscarinic agents, or a combination thereof is often used [2]. Type 1 and type 2 isoenzymes of -reductase are present throughout the body [3], and dutasteride, a dual -reductase inhibitor, acts competitively and specifically on type 1 and type 2 isoenzymes to inhibit the conversion of testosterone to the more potent DHT [4–6]. In comparison with finasteride, a -reductase inhibitor selectively acting on type 2 isoenzyme [7], dutasteride is a 45-fold greater inhibitor of type 1 -reductase, and a 2.5-fold greater inhibitor of type 2 -reductase [8–10]. Patients with BPH who do not respond suitably to pharmacotherapy often undergo transurethral resection of the prostate (TUR-P), the gold standard for the surgical treatment of BPH, and microwave thermotherapy [11] in order to improve symptoms of bladder