EFFECTS OF THE ANDROGEN ANTAGONIST CYPROTERONE ACETATE ON THE TESTICULAR STRUCTURE, SPERMATOGENESIS AND ACCESSORY SEXUAL GLANDS OF TESTOSTERONE-TREATED ADULT HYPOPHYSECTOMIZED RATS

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Abstract
SUMMARY: 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.