Abstract
The effect of testosterone and estradiol on the prostate of castrated rats (rat prostatic hyperplasia model after combined treatment with testosterone and estradiol) were investigated by histopathologically and immunohistochemical procedures. The castrated rats were treated for 6 weeks with 1) testosterone 1 mg/animal and 2) testosterone 1 mg/animal plus 17beta-estradiol (estradiol) 10 μg/animal. Histopathologically, glandular hyperplasia of the ventral prostate and glandular hyperplasia with fibromuscular stromal proliferation in the dorsolateral prostate, was clearly observed. Immunohistochemical localization of glutathione peroxidase (GSH-PO) which effectively reduces the lipid peroxides, was predominantly observed in the glandular epithelial cells of the ventral prostate. The intensity of GSH-PO staining in the glandular epithelial cells was remarkably decreased after castration, and that it was clearly recovered by testosterone or testosterone plus estradiol treatment to the castrated rats. In contrast, GSH-PO was clearly observed in the glandular epithelial cells of the dorsolateral prostate following testosterone alone or testos-terone plus estradiol. Androgen receptor (AR) is mainly localized in nuclei. In the dorsolateral prostate, AR was also detected in the nuclei of the proliferated stromal fibromuscular cells. Furthermore, immunodetectable AR rapidly declined after androgen withdrawal and returned to intact levels of staining intensity after androgen replacement. These findings strongly suggest that expressions of GSH-PO and AR in the prostate are testosterone-dependent. It is concluded that immunohistochemical analysis, using GSH-PO and AR, may be a useful method for prediction of the effects of androgen action on the rat prostate.
