LIPIDS PRESENT IN BRAIN AND NERVOUS TISSUE 761 



intraperitoneal administration of pentylene tetrazole and physostigmine 

 salicylate. Within fifteen minutes after the injection of ACTH, the rate of 

 phospholipid synthesis in the brain was increased. These results are inter- 

 preted as indicating that the brain phospholipids are utilized during activ- 

 ity. Moreover, they prove that the turnover of phospholipids is controlled 

 by a humoral mechanism. 



In addition, the brain is especially susceptible to vitamin E deficiency. 

 Heinrich and Mattill 316 demonstrated that marked changes in the total 

 lipids occurred at various stages of the vitamin E deficiency induced by 

 diet; furthermore, there was a marked increase in the cholesterol content. 

 The proportion of free cholesterol was increased to a much greater extent 

 than was that of the total cholesterol. 



e. The Effect of Hyperinsulinism on Brain Lipids. Randall 317 was the 

 first to demonstrate a reduction in brain phospholipid and neutral fat, 

 following a prolonged insulin hypoglycemia. Page and associates 149 

 were unable to note that a single dose of insulin exerted any significant 

 effect upon the total fat in the brain of rabbits, although the fatty acids 

 were decreased by 14% and the cholesterol was increased by 10%. 

 McGhee et aZ. 318 demonstrated a consistent and significant decrease in 

 brain lipid phosphorus of about 10%, following massive doses of insulin. 

 The decrease could not be reversed by the administration of glucose or of 

 lecithin. The authors consider this decrease to be a direct and perhaps 

 irreversible effect of hyperinsulinism. 



f. The Effect of Choline Deficiency on Brain Lipids. Choline deficiency 

 has been shown by Foa, and associates 319 to have no effect upon the total 

 lipid, total phospholipid, sphingomyelin, lecithin, cephalin, or cholesterol 

 content of rat brain. This constancy in brain lipid values is maintained 

 in spite of the fact that choline deficiency in the diet results in a depressed 

 value for lecithin in the liver, which can be reversed by choline supple- 

 ments. On the other hand, the level of sphingomyelin, cephalin, or chole- 

 sterol in the liver is not influenced by the choline-free diet. 



(4) The Lipid Composition of Nerves 



Palladin and his associates 320 compared the lipid and nitrogen content 

 in various parts of the nervous system of dogs. The highest amount of 



316 M. R. Heinrich and H. A. Mattill, Proc. Soc. Exptl. Biol. Med., 52, 344-346 (1943). 



317 L. O. Randall, /. Biol. Chem., 133, 129-136 (1940). 



318 E. C. McGhee, E. Papageorge, W. L. Bloom, and G. T. Lewis, /. Biol. Chem., 190, 

 127-132 (1951). 



319 p. p. Foa, H. R. Weinstein, and B. Kleppel, Arch. Biochem., 19, 209-212 (1948). 



320 A. V. Palladin, E. I. Rashba, and R. M. Helman, Ukrain. Biochem. Zhur., 8, No. 1, 

 5-26 (1935); Chem. Abst., SO, 5277 (1936). 



