Inhibition of action of pituitary hormones by animal sera

In these ‘Proceedings’ for 1934 (Thompson and Cushing, 1934) appeared the report of an experimental effort to reproduce the clinical syndrome of pituitary basophilism in a puppy by means of injections of a gonadotropic extract prepared from sheep-pituitaries. Certain striking effects were observed in the experimental animal, namely, obesity, a lowered metabolism, sexual inactivity, and retardation of growth with skeletal dystrophy. These effects, while in some respects suggesting the human disorder, basophilism, could in others be interpreted broadly as an inhibition of normal processes simulating hypophysectomy. Further experiments with other gonadotropic preparations have since been made, and each time some form of inhibition has developed in the animals. In order to investigate the nature of these reactions the blood sera of some of the injected dogs were tested by methods suggested by Collip and his co-workers in their several reports concerning “antihormones” (Anderson and Collip, 1934,a ,b ,c ; Bachman, 1935; Bachman and Collip, 1934; Collip, 1934; Collip and Anderson, 1935). It will be recalled, briefly, that Anderson and Collip (1934,a ) first detected an antagonistic activity of the blood sera of animals which had become insensitive to injected thyrotropic extract. Bachman, Collip, and Selye (1934) shortly afterwards stated in regard to gonadotropic extract that “the loss of sensitivity is limited to the gonadotropic preparation with which the animals have been injected previously. Animals which become insensitive to pituitary implants remain sensitive to A. P. L.* andvice versa ”. The term “antihormone”, subsequently used by Collip and his co-workers to indicate this inhibitory action, is now well known and requires no explanation.