The mechanism of epristeride against benign prostatic hyperplasia

Inhibitory Effect of Astaxanthin on Testosterone-Induced Benign Prostatic Hyperplasia in Rats

This study investigates the inhibitory effect of astaxanthin (AST) on testosterone-induced benign prostatic hyperplasia (BPH) in rats. Except for the sham operation, BPH model rats were randomly assigned to five groups: the BPH model control rats, AST-treated BPH model rats (20 mg/kg, 40 mg/kg, and 80 mg/kg), and epristeride (EPR)-treated BPH model rats. After treatment, as compared with the BPH model control rats, the prostate and ventral prostate weights of the AST-treated rats decreased, while there was a marked decline in the 80 mg/kg AST-treated rats. The same effect was also observed in the prostate index and ventral prostate index. The proliferation characteristics of epithelia observed in the BPH model control group were gradually alleviated in the AST-treated rats. As compared with the BPH model control rats, lower epithelial thicknesses of prostates and fewer secretory granules in epithelia were observed in the AST-treated rats. The superoxide dismutase (SOD) activity of prostates increased in all the AST-treated rats with a significant increase in the 40 mg/kg and 80 mg/kg AST-treated rats. The testosterone (T) and dihydrotestosterone (DHT) levels of prostates in the AST-treated groups were lower than those in the BPH model control group, and a significant decline was found in the T level of prostates in the 40 g/kg and 80 mg/kg AST-treated rats and the DHT level of prostates in the 40 mg/kg AST-treated rats. These results indicate that AST might have an inhibitory effect on T-induced BPH in rats, possibly due to SOD activity regulation and T and DHT levels.

IN VITROEFFECTS OF EPRISTERIDE ON SPERM IN RATS, DOGS AND MAN

The study was conducted to evaluate in vitro effects of epristeride on sperm in rats, beagle dogs and man. Semen samples were divided into 4 groups and treated with vehicle and epristeride. Motility and motile rate of sperm were videotaped and analyzed with CASA system after 1 h and 2 h incubation periods. Percentage of motile sperm (MOT) of rat sperm decreased after the treatment with epristeride (final concentrations were 0.6, 6 and 60 micromol/L) for 1 h, and MOT of rat sperm treated with middle dose and high dose levels of epristeride also decreased after 2 h, while MOT of dog sperm that treated with three dose levels of epristeride decreased after 2 h. Amplitude of lateral head displacement (ALH) and MOT of human sperm decreased after 2 h with 4.8 micromol/L epristeride treatment. Curvilinear velocity (VCL) and straight-line velocity (VSL) of rat sperm and human sperm changed after 2 h, but there were no significant differences. Therefore, epristeride had a toxic effect on sperm, and the effect varied in different species.

Effect of epristeride on the expression of IGF-1 and TGF-beta receptors in androgen-induced castrated rat prostate

The development of benign prostatic hyperplasia (BPH) is an androgen-dependent process that may be mediated by a number of locally produced growth factors. Among them, insulin-like growth factor 1 (IGF-1) and transforming growth factor beta (TGF beta) are thought important in regulating prostate growth and homeostasis, and their expression undergoes changes in proliferative prostatic disease. Epristeride, a 5 alpha-reductase inhibitor, is an effective drug in the treatment of BPH, inducing regressive changes in the prostate. This study was designed to assess the effects of epristeride on expression of these two factors at mRNA and protein levels in castrated rats maintained with exogenous testosterone. Epristeride treatment caused significant reduction in ventral prostate weight in a dose-dependent manner. There was a positive correlation between IGF-1 mRNA expression and ventral prostate weight and an inverse correlation between TGF-beta 1 mRNA expression and ventral prostate weight. Immunohistochemistry showed strong IGF-1 receptor immunoreactivity in the prostatic epithelial cells of untreated animals. In situ hybridization demonstrated high levels of IGF-1 mRNA expression both in the prostatic stromal and epithelial cells of untreated rats. In treated rats, both IGF-1 receptor protein and IGF-1 mRNA levels decreased significantly, and IGF-1 mRNA was mainly expressed in prostatic stromal cells. Weak expression of TGF beta receptors at the protein level and TGF beta at the mRNA level were found in the prostatic hyperplastic epithelial cells of untreated rats. In treated animals, intense T beta RII immunoreactivity was observed in epithelial cells, and a higher level of TGF beta mRNA was observed in both epithelial cells and stromal cells compared with control animals. In our opinion, the effect of epristeride on rat prostatic atrophy might be mediated via local growth factor(s).