Immunohistochemistry of the canine prostate

In the canine prostate, glandular epithelial cells showed uniformly intense nuclear staining for androgen receptor (AR). AR was also localized in the nuclei of the fibro-muscular stromal cells. Immunoreactivity of 5 alpha-red uctase type I was positive in most glandular epithelial cells. No fibro-mus cular stromal cells were stained. Immunolocalization of 5 alpha-reductase t ype II was clearly detected in the interacinar fibro-muscular stromal cells , but not in the glandular epithelial cells. After treatment with antiandro gen, chlormadinone acetate (CMA) on canine spontaneous benign prostatic hyp erplasia (BPH), glandular atrophy was evident. The interacinar fibro-muscul ar stroma was prominent. The nuclear staining for AR in both epithelial and stromal cells was remarkably decreased. Furthermore, the immunoreaction fo r 5 alpha-reductase type I in most glandular epithelial cells was negative or very weak. The immunoreaction of 5 alpha-reductase type II in the intera cinar fibro-muscular stromal cells was negative or very weak. The decreased AR-immunostaining may be explained by the decrease in the number of AR and it may play a key role in the down-regulation of 5 alpha-reductase gene ex pression by CMA. The atrophy after treatment with CMA may be due to shrinka ge of both glandular and stromal compartments in the prostate tissue.