5α‐reductase activity in epithelium and stroma of prostates from intact and castrated dogs treated with androstenedione, the aromatase inhibitor 1‐methyl‐1,4‐androstadiene‐3, 17‐dione, and cyproterone acetate

Abstract

In addition to the histology of epithelial and stromal elements of prostates from intact dogs (group 0) and castrated dogs (group I), the latter of which were treated with androstenedione (group II), androstenedione plus the aromatase inhibitor 1-methyl-1,4-androstadiene-3,17-dione (group III), or androstenedione plus aromatase inhibitor and cyproterone acetate (group IV) (Habenicht and El Etreby: The Prostate 11:133-143, 1987) it was of interest to study the influence of such in vivo treatment on the prostatic 5 alpha-reductase, which is responsible for the cellular conversion of testosterone to 5 alpha-dihydrotestosterone. Michaelis constants (KM) and maximal activities (Vmax) of 5 alpha-reductase were determined under optimized incubation conditions in mechanically separated epithelium and stroma. The metabolites were separated by high-performance liquid chromatography and determined radiometrically. The main results were: 1) The mean KM (nM +/- SEM) was significantly (P less than .001) higher in epithelium (892 +/- 132) than stroma (70 +/- 11). The same was true concerning the Vmax (pmol.mg protein-1.h-1 +/- SEM) in epithelium (54.6 +/- 5.8) as compared to stroma (13.0 +/- 2.0). 2) No specific in vivo or in vitro effect of the aromatase inhibitor on the KM and Vmax data was found. 3) In prostates of intact dogs and dogs of group II the proportion of epithelial 5 alpha-reductase exceeded distinctly that of stromal 5 alpha-reductase. 4) In groups I, III, and IV the proportion of epithelial 5 alpha-reductase was rather low. These data were discussed in the light of the histological findings.

Models for studying benign prostatic hyperplasia

“…Canine BPH is uniform and diffuse, occurring thoughout the entire gland and it primarily involves the glandular epithelial cells, with less stromal involvement. 45,61,65,67,68 Tunn and his colleagues 69 reported that the concentration of 5a-reductase, which converts testosterone to dihydrotestosterone, an active androgen, is higher in the prostatic epithelium than in the stroma in dogs. This is not the case in man which may explain why the hyperplasia is mainly epithelial in dogs and stromal in men.…”

Estudio ultrasonográfico e histológico de la evolución de un modelo canino de hiperplasia benigna de próstata inducida por hormonas

“…La HBP canina es, generalmente, uniforme y difusa; aparece por toda la glán-dula e involucra, fundamentalmente, las células del epitelio glandular, con una menor afectación de la estroma que en la especie humana. Esto podría deberse a que, a diferencia de lo que ocurre en la próstata humana, las concentraciones de 5a reductasa en la especie canina son mayores en las células epiteliales que en las estromales 27 .…”

Glutathione-Peroxidase (GSH-PO) and Androgen Action in Prostate: An Immunohistochemical Study

“…It is generally accepted that estrogens play a critical role in the etiology of canine and human benign prostatic hypreplasia [2,21,22]. The dorsolateral prostate of the rat has been shown to be very sensitive to estrogen [3].…”