SATURATED FATTY ACIDS 37 



tomized) ; this hormone has also been shown to inhibit the incorporation of 

 deuterium into fatty acids of rats in vivo. '^- 



c. The Effect of Adrenal Hormones. The data on the effect of the 

 adrenocortical hormones on lipogenesis have been somewhat contradictory. 

 In Houssay cats, the administration of cortisone reduced lipogenesis. i^' 

 Welt and Wilhelmi^^'- also reported that ACTH (adrenocorticotropic hor- 

 mone, which stimulates the production of cortisone) hkewise decreases 

 fatty acid synthesis. On the other hand, Altman et al.^^^ found that, when 

 cortisone and insulin were given concomitantly, they exerted a synergistic 

 effect upon lipogenesis in perfused rat hver, without affecting the synthesis 

 of cholesterol. Epinephrine has been shown to depress the incorporation 

 of acetate into fatty acids. ^^° 



d. The Effect of the Thyroid Gland. Spirtes, Medes, and Weinhouse^^" 

 reported that the rate of oxidation of acetate was 30 to 70% higher in the 

 livers of hyperthyroid rats than in those of normal rats, while the level of 

 oxidation was found to be reduced to below normal in athyroid animals. 

 No differences in acetoacetate synthesis from acetate were observed be- 

 tween the normal and the abnormal animals. On the other hand, although 

 fatty acid synthesis was as high or higher in liver slices from hyperthyroid 

 rats as in those from normal animals, only a negUgible fatty acid synthesis 

 obtained in the hvers of athyroid rats. The latter situation was similar to 

 that which occurs in fasting normal animals. ^^^ 



(7) Factors Other Than Hormones Affecting the Biosynthesis of Fatty Acids 



in Animals 



a. Fetal Synthesis. Fat synthesis in the embryo varies markedly from 

 that occurring in older animals. Thus, in the case of pregnant rabbits, 

 Popjak and Beeckmans^^^ found a greater synthesis of fatty acids in fetuses 

 than in their mothers. It was also noted that the rate of cholesterol syn- 

 thesis in the fetus was highest in the hver, while the bulk of the fatty acid 

 formation occurred in the extrahepatic tissues. ^^" However, the highest 

 rate of fatty acid synthesis was in the mammary tissue of the mother. ^^^ 



b. Nutritional Status. The nutritional condition has likewise been 



'" I. D. Welt and A. E. Wilhelmi, Yale J. Biol. Med., 23, 99-111 (1950). 



'" K. I. Altman, L. L. Miller, and C. G. Blv, Arch. Biochem. Biophys., 31, 329-331 

 (l'.i51). 



'" M. A. Spirtes, G. Medes, and S. Weinhouse, XIX Intern. Physiol. Congress, Mon- 

 treal, Aug.-Sept., 1953, Abst., 789-790, /. Biol. Chem., 204, 705-713 (1953). 



'^^ G. Popjdk and M. L. Beeckmans, Biochem. J., 44, xxxvi-x.xxvii (1949). 



'^* G. Popjdk and M. L. Beeckmans, Biochem. J., 44> xxxvii (1949). 



