Comparison of the effects of cyproterone, cyproterone acetate and oestradiol on testicular function, accessory sexual glands and fertility in a long-term study on rats.

Abstract

Summary. Treatment of adult male rats with oestradiol, cyproterone acetate or cyproterone affected spermatogenesis, accessory sexual glands and fertility in different ways. Suppression of Leydig cells, spermatogenesis, accessory sexual glands and fertility ran parallel in oestradiol-treated animals. High doses of cyproterone acetate caused severe suppression of the accessory sexual glands and fertility but had only a slight inhibitory influence on spermatogenesis, Leydig cells were only temporarily affected. With high doses of cyproterone, Leydig cells were over-stimulated initially but returned to normal appearance during treatment. There was almost no effect on spermatogenesis but the accessory sexual gland weights and fertility were markedly reduced. Recovery from any changes was rapid after cessation of cyproterone acetate and cyproterone treatment but not after oestradiol. Lower doses of cyproterone acetate and cyproterone did not affect testicular morphology but significantly depressed the accessory sexual gland weights. Different mechanisms of action for the three steroids are discussed. Objections are raised against the use of cyproterone acetate for the control of male fertility.