THE GONADOTROPIC HORMONES 



of the immature rat's ovary, caused by a follicle-stimulating 

 extract, is greatly increased if a luteinizing substance also be 

 given. A puzzling recent observation of great interest is the 

 potentiating action, at certain times, of the serum of animals 

 receiving a prolonged course of injections of gonadotropic 

 pituitary extract to produce antihormone which, of course, 

 has the opposite action. This phenomenon has been studied 

 by Collip (1937), Thompson (1937), and Rowlands (1938). 

 Thompson's experiments illustrate how this information was 

 obtained. A horse and two dogs received repeated injections 

 of sheep pituitary gonadotropic extract. The effects of their 

 sera on the gonadotropic action of the extract in hypophysec- 

 tomized or normal immature rats was ascertained at inter- 

 vals of 7-20 days. Finally, the sera were found to contain a 

 substance or substances which augmented the action of the 

 extract on the immature rat's ovary about threefold. Sera 

 which were obtained 50-80 days after the injections were 

 started had the maximum augmenting effect. The active sub- 

 stance(s) was in the pseudoglobulin fraction which also con- 

 tains immune bodies and antihormones, if these are present. 

 Thompson suggested that an antihormone to "pituitary an- 

 tagonist" (see the foregoing section) may have been formed. 

 Rowlands is inclined to concur with this view and enumerates 

 reasons in support (specificity of effect for pituitary gonado- 

 tropic extract only, especially of extracts probably rich in 

 "antagonist," lack of phenomenon with nongonadotropic 

 pituitary extracts with other effects, etc.).'^ 



By direct extraction of the anterior pituitary, a substance 

 augmenting the action of certain gonadotropic extracts (e.g., 

 follicle-stimulating extract as extract of urine of women after 

 spaying or after the menopause, endometrium of the preg- 



"^ In CoUip's experiments (sheep pituitary extract as "antigen" injected into 

 lambs) antihormone was demonstrated later. Katzman, Wade, and Doisy (1937) 

 who unusuccessfully attempted to produce antihormone effects by pituitary homo- 

 implants in rats, remarked that the serum obtained at the end of treatment (7-9 

 months) augmented the gonadotropic effects of implants. 



[117] 



