STORAGE OF CAROTENOIDS AND OF VITAMINS A 525 



ministration of carotene'^"'^^^ or of vitamin A itself /-°'^'^^~^^^ except follow- 

 ing very high dosages. The difference in storage cannot be ascribed to dif- 

 ferences in weight or growth rates,®^^ and it is believed to be an example of 

 true sexual dimorphism. When moderate dosages (40 to 320 I.U./day) of 

 ^'itamin A were given to rats, Moore et al.^^^ noted a greater efficiency of 

 storage of vitamin A in females than in males. Booth®^^ likewise observed 

 that the depletion of vitamin A from the liver of rats on a \dtamin A-free 

 diet was more rapid in the case of male rats than in females. Hence, the 

 ratio of storage of the female vs. the male increased with time. The thresh- 

 old dose below which no storage takes place was likewise found to be 

 higher in male rats than in female rats.®^* When the rats were placed on a 

 vitamin A-free diet, deficiency symtoms appeared in the males slightly 

 sooner than in the females ;^^^'*^'^ moreover, the females on the deficient diet 

 outlived their brothers, although the differences in survival time were not 

 great. ^^^ Goodwin^^^ reported that carotenoids were more abundant in the 

 organs of females than in those of males, in species in which they were ab- 

 sorbed. However, Booth^^^ stated that the absorption efficiency of caro- 

 tene and the conversion to vitamin A are not functions of sex. Lemley and 

 associates"^ failed to note sex differences in the storage of vitamin A in rats, 

 but it may be that some of the conditions were different from those in the 

 experiments of other investigators. There is no doubt that the proponder- 

 ance of evidence supports the concept that females store greater amounts 

 of \'itamin A in their livers than do males under similar conditions. 



A sex difference in Aatamin A storage in the kidney has also been re- 

 corded,"^ but this appears to be in the opposite direction than is the case 

 with liver vitamin A. When the amount of vitamin A available to rats is 

 loAV, the kidney exerts a priority for storage over the livers. ^^^'^^^-^^^ After 

 moderate doses a higher level of vitamin A occurs in the kidneys of male rats 

 as compared with female rats.^^^-®^"-^*^'®^^ Moore and co-workers**^ re- 

 ported that the sex difference in vitamin A storage in the kidney is ex- 

 hibited at moderate dosages (40 to 320 I.U./day), and that it decreases at 

 high intakes of the vitamin. 



(a) The Effect of Sex Hormones. The removal of the sex hormones from 

 the area of activity by castration has been shown to affect the \'itamin A 

 storage of rats. Bult and Sorgdrager**^ reported that castrated rats lost 



^* V. H. Booth, Biochem. J., 47, xliii (1950); /. Nutrition, 48, 13-30 (1952). 



**^ T. Moore, I. M. Sharman, and R. J. Ward, Biochem. J., 49, xxxix-xl (1951). 



««6 G. C. Esh and S. Bhattacharya, Indian J. Physiol. Allied Sci., 5, 15-20 (1951). 



«8' J. Mayer and W. A. Krehl, Yale J. Biol. Med., 20, 403-405 (1948). 



«88 E. Eden and T. Moore, Biochem. J., 49, 77-79 (1951). 



«89 A. R. Bult and C. J. Sorgdrager, Ned. Tijdschr. Geneesk., 84, 1963-1970 (1940). 



