Effects of the antioestrogen tamoxifen on steroid induced morphological and biochemical changes in the castrated dog prostate.

The effect of the antioestrogen tamoxifen (TA) was investigated in different types of steroid-induced benign prostatic hyperplasia (BPH) in the castrated dog by histological, histochemical and biochemical analysis. A 6 months treatment with oestradiol-17 beta (E2) alone resulted in cystic and stromal hyperplasia and squamous epithelial metaplasia with a striking prostatic weight increase DNA and RNA content of the total glands increased significantly. The histochemical results and zinc values indicated the loss of normal epithelial function due to metaplatic transformation. The E2 induced cystic and metaplastic hyperplasia was prevented by TA while the stromal proliferation was significantly decreased but not abolished. Biochemical determinations revealed an effect similar to castration. After combined treatment with E2 and 3 alpha-androstanediol (3 alpha-diol) TA completely suppressed squamous metaplasia. A 3 alpha-diol induced glandular proliferation, monitored by a positive histochemical reaction, and significantly elevated zinc, DNA and RNA contents prevailed. A partial stromal stimulation indicates stimulating effects of 3 alpha-diol too on the stroma. The antioestrogenic effects of tamoxifen on experimentally induced BPH mainly manifest at the E2 induced epithelial alterations. The abolishing effects at the stromal level are distinct but not so impressive.