640 VI. OCCURRENCE OF LIPIDS IN THE ANIMAL 



of fatty livers in insulin-treated depancreatized dogs could be prevented by 

 the feeding of raw pancreas. Hershey alone 572 and later with Soskin 573 re- 

 ported that crude egg yolk "lecithin" could be used to combat fatty livers 

 as effectively as could raw pancreas. Hershey used lecithin in place of raw 

 pancreas because he considered that the development of fatty livers was a 

 result of failure in fat transport rather than of a disturbance in its digestion. 

 Since the phospholipids were known to be primarily concerned with the 

 former function, lecithin was selected to test its effectiveness in removing 

 fat from the liver. 673 



A renewed stimulus to the development of the problem followed the dis- 

 covery by Best, Hershey, and Huntsman 574 that fatty livers could readily 

 be produced in normal rats by feeding a diet high in saturated fats. The 

 availability of the white rat for such studies made it possible to carry out 

 many more experiments at a fraction of the cost than was possible with de- 

 pancreatized dogs. The rats responded to lecithin feeding by maintaining 

 normal liver lipids when put on the liver-fattening diet. In determining 

 the fraction of lecithin which is responsible for the lipotropic action, 575 - 576 it 

 was found that sodium oleate, glycerophosphoric acid, and ethanolamine 576 

 were inactive ; however, it was noted that choline and a closely related com- 

 pound, betaine, were both highly active in preventing the accumulation of 

 fat in the liver. It was also reported that mice developed fatty livers on an 

 appropriate dietary regimen, and that they could be prevented by choline. 577 

 Choline is trimethylhydroxyethylammonium hydroxide : 



HOCH 2 CH 2 N+(CH 3 ) 3 (OH) - 



while betaine is the anhydride of the corresponding acid with the structure : 

 0:CCH 2 N + (CH 3 ) 3 



A- 



For a complete discussion of the chemical properties of these compounds, 

 the reader is referred to the review of Best and Lucas, 550 and to pages 426 

 to 432 of Volume I. 



b'. The Effect of Choline on Various Types of Fatty Livers: The effec- 

 tiveness of choline in preventing fatty livers due to high-fat diets was con- 



572 J. M. Hershey, Am. J. Physiol, 98, 657P-658P (1930). 



673 J. M. Hershey and S. Soskin, Am. J. Physiol, 98, 74-85 (1931). 



574 C. H. Best, J. M. Hershey, and M. E. Huntsman, J. Physiol, 75, 56-66 (1932). 



575 C. H. Best, J. M. Hershey, and M. E. Huntsman, Am. J. Physiol, 101, 7P (1932). 

 676 C. H. Best and M. E. Huntsman, /. Physiol, 75, 405-412 (1932). 



877 C. H. Best, M. E. Huntsman, and O. M. Solandt, Trans. Roy. Soc. Can., Sect. V, 26, 

 175-176 (1932). 



