Prevention by Cyproterone Acetate of Androgenic, But Not of Gonadotrophic, Elicitation of Persistent Estrus in Rats12

Abstract

Persistent estrus (PE) occurs after treatment of female nursling rats with testosterone proplonate (TP) or with human chorionic gonadotrophin (HCG). Studies were made to ascertain if development of PE could be inhibited by simultaneous treatment of nurslings with an anti-androgen cyproterone acetate (Cyp A). Cyp A largely prevented TP from eliciting PE, presumably by direct action of Cyp A on the central nervous system as a target organ. Cyp A prevented the production of clitoral hypertrophy by HCG, showing that Cyp A also inhibited stimulation provided by endogenous ovarian androgens. Cyp A did not prevent PE caused by HCG, however, this and other evidence led to rejection of the postulate that the PE produced by HCG was due to "masculinization" by ovarian androgens. Therefore, the collective term, tonic function of the central nervous system, was used to describe not only the condition acquired at an early age by females treated perinatally with various steroids or HCG, but also the status appearing soon after birth in normal males and later in life in normal females.