THE GONADOTROPIC HORMONES 



2. Inhibition. — The administration of certain anterior 

 pituitary extracts may inhibit the gonad-stimulating effect 

 of prolan. This phenomenon is best observed after the intra- 

 peritoneal administration of the anterior pituitary extract. 

 The mechanism of this inhibitory action is not known; the 

 obvious possibility that a local action on the ovary is im- 

 portant has not been investigated. 



The doctrine of antihormones as related to prolan.^^ — The 

 degree of purity of the best preparations of prolan is not 

 known. Like similarly impure anterior pituitary extracts, 

 preparations of prolan, if repeatedly administered for weeks 

 or longer, produce progressively reduced gonadotropic effects 

 until the organ affected — whether ovary or testis — is refrac- 

 tory to further treatment. "Antihormone" or a substance 

 inhibiting the action of the extract in fresh, non-injected 

 animals can be detected in the serum at this time. Its site 

 of formation may be the reticulo-endothelial system.''' Are 

 these phenomena important physiologically? Probably not. 

 The chorionic epithelium of the placenta of women secretes 

 enormous quantities of prolan into the blood throughout 

 pregnancy, although the peak of formation suddenly appears 

 at about the end of the second lunar month. There is no evi- 

 dence of any formation of antihormone by the tissues of 

 pregnant women. It appears that the numerous investiga- 

 tions of the formation and characteristics of prolan-anti- 

 hormone represent, at most, contributions to a new field of 

 immunology. 



Eichbaum and Kindermann (1935) and Kindermann and 

 Eichbaum (1936) have published several communications on 



■5 Other experiments in which prolan was used are discussed in chap, iii (pp. 

 iioff.). 



'^Experiments of Gordon, Kleinberg, and Charipper (1937) in splenectomized 

 rats to some of which trypan blue was also administered to "block" the reticulo- 

 endothelial system. The refractory (non-responsive) condition of the ovary ap- 

 peared much later in splenectomized rats also receiving trypan blue. Ten rat-units 

 of prolan were injected daily. When refractoriness of the ovary finally appeared, it 

 was attributed to the production of antithormone by redeveloped reticulo-endo- 

 thelial tissue. 



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