STEROID HORMONES 



steroid hormone synthesis should not be oxci looked. Estrone per- 

 fused through the rat liver or iueuhaled wilh liver brei is at least in 

 part converted to a-estradiol, that is, into more active substance. 

 Estrone on this basis may be considered a precursor of a highly active 

 foUiculoid. Whatever the logical distinction may be, a special role in 

 steroid hormone synthesis may have to be assigned to the liver. 



Destruction of Steroid Hormones 



The nature of steroid hormone degradation in animals has been 

 more thoroughly investigated than hormone anabolic processes. The 

 available data has been reviewed in some detail (9). With certain 

 exceptions, most of the data have been arrived at by determination of 

 urinary steroid catabolites in normal human and animal urines or 

 similar urinary analyses after the administration of active hormone. 

 In the case of mammalian subjects, certain of the hormonally active 

 steroids probably undergo the series of conversions given in scheme I. 



Adopting the convenient classification of the hormonally active 

 steroids on the basis of number of carbon atoms it can be seen tliat ihe 

 identified catabolic end product of C21 hormones is pregnanediol. It 

 is not established that this is the only end product. Furthermore, 

 pregnanediol is not found in the urine of certain species (c. g., cat and 

 monkey) nor is it found therein after progesterone administration. 

 Finally, quantitative studies indicate that only a portion of administered 

 progesterone and desoxycorticosterone is converted to pregnanediol. 

 It is probable, therefore, that other breakdown products of the C21 

 steroids should be sought. The pregnanolones, which have been 

 found in human pregnancy urine would seem to be likely metabolites, 

 but attempts to identify them in urine after the administration of C21 

 steroids to human and animal subjects have thus far been unsuccessful. 



For the C19 steroids we have somewhat more detailed informa- 

 tion as to possible modes of catabolism. Dorfman and Hamilton 

 have attempted to set up a balance sheet for testosterone administered 

 to eunuchoid men. After making certain assumptions the data indi- 

 cate that androsterone may be taken as the principal catabolite, 

 accounting for a little over 60% of the administered hormone. In 

 somewhat better controlled experiments with guinea pigs, isoandros- 

 terone (the principal urinary catabolite to be identified in this species) 



