Synergic inhibitory effects of the aromatase inhibitor 1-methyl-androsta-1, 4-diene-3, 17-dione and the antiandrogen cyproterone acetate on androstenedione-induced hyperplastic effects in the prostates of castrated dogs.

We examined whether the induction of estrogen-related hyperplastic changes in the prostate (ie, activation and stimulation of the stroma, especially of the smooth muscle) of castrated beagle dogs was reproducible. The effectiveness of the aromatase inhibitor 1-methyl-androsta-1, 4-diene-3, 17-dione (1-Methyl-ADD) in antagonizing such estrogen-related alterations was investigated in comparison with a combined treatment of 1-Methyl-ADD and the antiandrogen CPA. These studies have demonstrated the suitability of the androstenedione model for testing the efficacy of aromatase inhibitors. In addition, it has been demonstrated that an aromatase inhibitor in combination with an antiandrogen can synergically inhibit the glandular and stromal components of the prostate.