The effect of the anti-androgen 1,2-alpha-methylene-6-chloro-delta-4,6-pregnadiene-17-alpha-ol-3,20-dione-17-alpha-acetate (cyproterone acetate) on the development of the mammary glands of male foetal rats

Treatment of pregnant rats with an anti-androgen (1,2α-methylene-6-chloro-Δ4,6-pregnadiene-17α-ol-3,20-dione-17α-acetate, 'cyproterone acetate') from the 13th day of pregnancy resulted in female organogenesis of the mammary glands, including the formation of nipples in the male foetuses and feminization of other male sexual characters. The continued development of the nipple primordium was also seen in all the subsequent foetal and postnatal stages even after termination of the treatment.

A more marked development of the foetal mammary tissue as compared with that of male controls was noted in the proximal areas of the mammary cord process between the 19th and the 21st day in male foetuses whose mothers had received the anti-androgen. In male foetuses of treated mothers, a further proliferation of the glandular tissue was also found after birth.

The role of androgens in the development of the mammary glands is discussed. It seems likely from our findings that the androgens of a male foetus inhibit the development of the mammary glands, emphasizing that for mammary development before puberty female gonadal hormones are not necessary.

The structure of the mammary glands and lactogenesis in feminized male rats

Male rats which had been prenatally under the influence of the androgenantagonist cyproterone acetate (1,2α-methylene-6-chloro-Δ4,6-pregnadiene-17α-ol-3,20-dione-17α-acetate) developed nipples, teat ducts, a complete gland cistern, main milk ducts, and mammary glands. As shown by histological criteria, lactogenesis was induced in these feminized rats with adequate hormone therapy after orchidectomy when adult. The mammae contained secretion and were indistinguishable from those of nulliparous female controls under identical hormone treatment. Since male rats have no teats, it was concluded that normally the anlagen for the mammary adnexa are prevented by foetal androgens from undergoing complete female organogenesis.

It seems that in male rat foetuses cyproterone acetate prevents endogenous testosterone from producing the incomplete organogenesis with athelia and without adnexa that normally occurs in the male mamma.

Effects of the androgen antagonist cyproterone acetate on the testicular structure, spermatogenesis and accessory sexual glands of testosterone-treated adult hypophysectomized rats

The antagonistic action of 1,2α-methylene-6-chloro-Δ4,6-pregnadiene-17α-ol-3,20-dione-17α-acetate (cyproterone acetate) to testosterone propionate (TP) on the testes and accessory glands was investigated in hypophysectomized adult male rats. Treatment of the animals began on the day of hypophysectomy and was continued for 21 days.

Daily subcutaneous injections of 0·3 or 1·5 mg. TP/100 g. body weight almost completely inhibited testicular atrophy and involution of the germinal epithelium.

Simultaneous administration of 0·3 mg. oestradiol/100 g. body weight did not influence the effect of testosterone propionate.

Cyproterone acetate inhibited the effect of testosterone propionate. The extent of inhibition was dose dependent. The antagonism to testosterone was manifested by reduction of testicular weight and by the inhibition of spermiogenesis. The latest stages of spermiogenesis were primarily influenced.

Intratesticular cyproterone acetate together with subcutaneous administration of TP caused similar effects in the testes to those of subcutaneous administration. However, regression of the germinal epithelium in the injected testis seemed to be more pronounced than in the contralateral testis.

The effects of TP on the accessory sex glands (prostate, seminal vesicles) were inhibited by simultaneous administration of cyproterone acetate. It is concluded that cyproterone acetate competitively inhibits the action of testosterone propionate on the target organs.