Some effects of cyproterone and cyproterone acetate on the reproductive physiology of the male rat.

Male rats were treated with 5 or 20 mg cyproterone acetate/kg/day or 20 mg cyproterone/rat/day for 1, 2, 3, 4, or 5 weeks. There was some reduction in fertility with both compounds, the maximum effect occurring after 5 weeks with the higher dose of cyproterone acetate and after 2 weeks with cyproterone. A significant increase in testosterone levels was found after treatment with the high dose of cyproterone acetate by 1 week and with cyproterone by 2 weeks. Dose-dependent atrophy of the seminal vesicles occurred after treatment with cyproterone acetate; with cyproterone atrophy occurred at 1 and 2 weeks but approximated to control values at 3, 4 and 5 weeks. Epididymal weights were reduced with the high dose of cyproterone acetate but the low dose had little effect. Reduction in the weight of the testes was only observed after 5 weeks of treatment with the high dose of cyproterone acetate. Since plasma testosterone levels were not depressed below normal values, accessory sex organ regression evidently resulted from the local antiandrogenic action of the drugs. There was some indication of interference with the secretory and absorptive activity of the lining cells of the epididymis but in general treatment with either steroid caused only relatively small and variable changes in the composition of epididymal plasma.