526 IX. CAROTENOIDS AND VITAMINS A 



their stores of vitamin A at rates intermediate between those for males and 

 for females. Booth^^** found that castrated young male rats lost their vita- 

 min A at a slightly slower rate than that of their unoperated controls; 

 this is interpreted to mean that castration in the males tends to induce femi- 

 ninity insofar as concerns vitamin A storage. Ovariectomized females 

 stored more vitamin A than did normal females, they lost their vitamin 

 A more slowly, and grew faster. The kidney vitamin A values for both 

 castrated males and ovariectomized females were found to be intermediate 

 between the values for normal males and for normal females. 



Moore and co-workers^^° observed variations in the vitamin A content of 

 kidneys, as influenced by the sex hormones. No appreciable variations 

 were noted in the \atamin A content of kidneys of male rats after castration, 

 without or with testosterone; the vitamin A levels of the kidneys under 

 these conditions were 37.4 I.U./g. for normal males, 42.7 I.U./g. for cas- 

 trated males given injections of testosterone, with unrestricted food in- 

 take. On the other hand, when the operated males were injected with 

 estradiol, the kidneys contained 4.6 I.U./g., a value expected in female rats. 

 These variations were not observed in the livers, where the concentrations 

 were highest and almost equal in the slowly gro^\^ng groups treated with 

 testosterone and with estradiol. It is also suggested that the sex effect 

 on vitamin A distribution can be only partially explained as a secondary 

 effect of its influence on growth. ^^^ 



d. The Effect of Thyroid Function on the Storage of Vitamin A. Al- 

 though there seems to be considerable evidence that the thyroid gland 

 influences the change of carotene to vitamin A, and hence might be in- 

 directly concerned with the extent of storage of vitamin A after the admin- 

 istration of carotene, it is of interest to inquire whether or not this gland 

 directly controls vitamin A deposition in the liver. Logaras and Drum- 

 mond^" and Baumann and Moore^^- reported that, when groups of normal 

 and hyperthyroid rats containing uniform stores of \'itamin A were fed a 

 diet low in vitamin A, the resulting hepatic stores were at least as high in 

 the thyroxine-treated animals as in the normal controls. Johnson and 

 Baumann ^^ also noted that hyperthyroid rats which had been fed halibut 

 liver oil stored as much vitamin A as did the normal controls. However, 

 in later work of Johnson and Baumann,*^i it was reported that, in rats of 

 similar size, the administration of desiccated thyroid hastened the deple- 

 tion of vitamin A reserves, while in hypothyroid conditions produced by 



690 T. Moore, I. M. Sharman, and R. J. Ward, Biochem. J., 49, xiii-xiv (1951). 

 651 G. Logaras and J. C. Drummond, Biochem. J., 32, 964-968 (1938). 

 692 C. A. Baumann and T. Moore, Biochem. J., 33, 1639-1644 (1939). 



