STUDIES ON THE PRESENCE OF GONADOTROPHIN-INHIBITING ACTIVITY IN HUMAN PINEAL EXTRACTS

Summary. The gonadotrophin-inhibiting activity of water-soluble extracts of human pineal glands from adult and prepuberal subjects was investigated. Extracts from adult subjects, injected daily for 12 days, did not modify the weights of anterior pituitaries, testes, seminal vesicles and ventral prostates of prepuberal rats. Those from adult and prepuberal subjects did not inhibit the increase of uterine weight in-duced by hcg in immature female mice. It is concluded that the presence of a gonadotrophin-inhibiting substance in the aqueous pineal extracts used seems unlikely. The presence of a gonadotrophin inhibitor in extracts of urine of human, simian and bovine origin has been reported by several investigators (Landau