LIPIDS PRESENT IN BRAIN AND NERVOUS TISSUE 749 



Gaucher's disease. Thierfelder and Klenk 261 are of the opinion that cere- 

 brosides are to be considered as general cell constituents under normal 

 conditions. 



c. Cholesterol in the Brain and Nervous Tissue. The white matter of 

 brain contains approximately four times as much cholesterol as does the 

 gray matter. Fieser and Fieser 262 cite a figure of 17% for the cholesterol 

 content of brain, based upon dry substance. On the water-free basis, the 

 values for cholesterol given in Table 8 are calculated as 15.6% in gray 

 matter and 10% in white matter. Yasuda 263 cites values for cholesterol 

 in gray and white matter, respectively, of 1.1 and 4.3% on the moist basis, 

 and of 6.3 and 13.4% on the dry basis. Although the brain of the newborn 

 rat was shown to possess the ability to synthesize cholesterol, Srere and 

 co-workers 7 were unable to demonstrate any synthesis whatsoever of choles- 

 terol from acetate in surviving brain slices of adult rats. According to 

 West and Todd, 217 the cholesterol content of spinal cord approximates that 

 of white brain matter, being 10 to 15% on the dry basis. Practically all 

 the cholesterol present in the brain is in the form of the free alcohol (see 

 Tables 13 and 14, on page 756). The amount of cholesterol is not in- 

 fluenced by inanition. 184 



d. The Presence of Proteolipids and of Strandin in the Brain. Folch 

 and Lees 264 described a new class of lipids which they call proteolipids. 

 This new type of compounds is made up of proteins and lipids, but instead 

 of the protein properties predominating, as is the case with lipoproteins, 

 the lipid properties prevail. Thus, in contradistinction to the behavior of 

 lipoproteins, proteolipids are insoluble in water, but are freely soluble in 

 chloroform-methanol-water mixtures. Although proteolipids were re- 

 ported in a number of tissues, they were present in the greatest concen- 

 tration in brain white matter. They were found to occur in descending 

 order in brain tumors, brain gray matter, heart, kidney, liver, lung, smooth 

 muscle, and skeletal muscle. They were, however, absent from blood 

 plasma. 



In a further study of the nature of proteolipids, Folch et aZ. 265 were able 

 to prepare proteolipids and strandin separately. Strandin, so named be- 



261 H. Thierfelder and E. Klenk, Die Chemie der Cerebroside und Phosphatide, Springer, 

 Berlin, 1930. 



262 L. F. Fieser and M. Fieser, Natural Products Related to Phenanthrene, 3rd ed., 

 Reinhold, New York, 1949, p. 94. 



263 M. Yasuda, /. Biochem. (Japan), 26, 203-210 (1937). 



264 J. Folch and M. Lees, /. Biol. Chem., 191, 807-817 (1951). 



266 J. Folch, I. Ascoli, M. Lees, J. A. Meath, and F. N. LeBaron, /, Biol. Chem., 191, 

 833-841 (1951). 



