Direct action upon avian target organs by the antiandrogen cyproterone acetate.

Abstract

AbstractAt ten days of age, intact male chicks had significantly larger combs than intact female chicks. Castration at four days of age eliminated the sex difference in growth of the comb. Growth of the comb, as a result of the secretion of endogenous androgens by the testes, was inhibited by inunction of the comb with small dosages of cyproterone acetate (Cyp A).Combs of other chicks were divided surgically into posterior and anterior portions of equal weight, thus providing two separate androgenic target organs in the same animal. The local action of Cyp A was investigated by inunction of this compound on the anterior or the posterior portion of the comb, along with simultaneous application of testosterone propionate to both portions. Small dosages of Cyp A antagonized the effect of androgen on the portion of the comb inuncted with Cyp A without affecting growth of the other target organ in the same animal. It was concluded that Cyp A exerted antiandrogenic actions directly upon target organs and was effective topically in doses too small to act systemically.The posterior portion of the comb, in comparison with the anterior, was more responsive both to the androgen and to the antiandrogen.