GONADOTROPIC SUBSTANCES 



pituitary was the responsible factor; later they found that 

 potentiation could be caused by pituitary extracts causing 

 gonad stimulation but no increased growth; recently they 

 have expressed the view that a new hormone, different from 

 any so far described, is responsible for potentiation. Others^-^ 

 believed that potentiation depends on a gonad-stimulating 

 fraction in anterior pituitary extracts and that in this respect 

 prolan behaves more like a "luteinizing" hormone. In hypo- 

 physectomized male and female rats gonad stimulation by 

 prolan is increased if even apparently ineffective doses of 

 anterior pituitary extract are simultaneously administered 

 (Collip, Selye, and Thomson, 1933; Evans, Pencharz, and 

 Simpson, Leonard and Smith, 1934). 



The antagonism oj prolan effects. — De Jongh and Laqueur 

 (1931) described signs of lessened activity of Leydig's cells in 

 male rats receiving oestrone. These effects could be abolished 

 or prevented by the administration of prolan except when 

 relatively large doses of oestrone were used. Later (1934) 

 they were of the opinion that the previous administration of 

 oestrone facilitated interstitial cell stimulation by prolan. 

 Spencer, D'Amour, and Gustavson (1932) showed that atro- 

 phy of the ovaries and testes of rats after oestrin administra- 

 tion was less if prolan was also given; the testes, however, still 

 weighed less than those of uninjected males. In castrated or 

 spayed animals prolan is said to lessen the effects of testis 

 hormone (Funk and Zefirow, 1932) and oestrone (Baum and 

 Pincus, 1932). Korenchevsky and others (1933), however, 

 reported that prolan administration did not alter the response 

 of the accessory organs of castrated male rats to testis 

 hormone. 



According to Evans, Simpson, and Austin (1933) and 

 Leonard (1934), some anterior pituitary extracts, adminis- 



^■i Leonard (1932, 1934); Fevold and others (1933); and Fevold and Hisaw (1934). 

 Anselmino and Hoffmann (1934) discussed the potentiation of prolan effects by an 

 extract of urine of women after the menopause or spaying. 



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