LIPIDS PRESENT IN RRAIN AND NERVOUS TISSUE 741 



other lipids change only to a minimum extent during fasting. On the other 

 hand, Cahn 215 reported that the value for phospholipids decreased during 

 inanition. De Boer 216 found only insignificant changes in the lipid con- 

 tent of the skeletal muscles in dogs when dehydration was produced by 

 withholding food and water. 



5. Lipids Present in the Brain and Nervous Tissue 



Brain and other nervous tissue is characterized by its high lipid content; 

 in fact, adipose tissue is the only tissue which contains a higher proportion 

 of lipids than does brain. According to West and Todd, 217 Donaldson 

 has indicated that the brain represents about 2% of the total body weight 

 in man, and the spinal cord and nerves account for an additional 0.4%. 

 The weight of the nervous tissue in a man weighing 68 kg. has been esti- 

 mated at 1620 g. ; the brain accounts for 1400 g. of this amount; the 

 spinal nerves are responsible for 151 g.; the sympathetic nerves weigh 

 approximately 30 g. ; the spinal cord amounts to 27 g. ; and the cranial 

 nerves make up 12 g. of the total. Although the function of the lipids of 

 the central nervous system has generally been assumed to be purely struc- 

 tural, certain brain preparations are able to break down phospholipids. 

 This fact led Stanley 218 to postulate that there may be a direct connection 

 between the metabolism of certain brain lipids and nervous and mental 

 activity. 



(1 ) The Lipid Composition of Normal Brain 



The classical experiments to determine the composition of brain were 

 carried out by the German chemist, Thudichum, whose first report 219 

 was made in 1874; this was extended and amplified 10 years later in a 

 subsequent publication. 220 



216 T. Cahn, Ann. physiol. physicochim. biol, 3, 4-60 (1927). 



216 B. de Boer, Am. J. Physiol, 147, 49-53 (1946). 



217 E. S. West and W. R. Todd, Textbook of Biochemistry, Macmillan, New York, 1951, 

 pp. 197, 421, 425. 



218 G. H. S. Stanley, Biochem. J., 50, xxiv (1952). 



219 J. L. W. Thudichum, Researches on the Chemical Constitution of the Brain, Report of 

 the Medical Officer of the Privy Council and Local Government Board, n.s. 3, No. 5, 

 113-247 (1874); cited by H. Thierf elder and E. Klenk, Die Chemie der Cerebroside und 

 Phosphatide, Springer, Berlin, 1930, p. 63. 



220 J. W. L. Thudichum, A Treatise on the Chemical Composition of the Brain, Bail- 

 liere, Tindall, and Cox, London, 1884; cited by H. Thierfelder and E. Klenk, Die Chemie 

 der Cerebroside und Phosphatide, Springer, Berlin, 1930, pp. 65 ff., and by G. Blix, Z. 

 physiol. Chem., 219, 82-98 (1933). 



