LIPID STORAGE UNDER ABNORMAL CONDITIONS 623 



Some investigators have ascribed to brown adipose tissue a special func- 

 tion during hibernation. The brown interscapular fat body is especially 

 developed in hibernating animals. It has been called the "hibernating 

 gland." Earlier literature on this subject has been reviewed by Ferdmann 

 and Feinschmidt, 490 and by Rasmussen. 491 



Later experiments of Wendt 492 suggested that the brown fat from hiber- 

 nating animals contains an active component which reduces metabolism. 

 Thus, it was found that, when extracts of the brown fat tissue of hibernat- 

 ing hedgehogs were injected into rats, the metabolism was reduced to the 

 extent of 20 to 30%. Hook 493 likewise reported that extracts from the 

 brown fat of the hibernating woodchuck or ground-squirrel produced a 

 similar decrease of metabolism in rats. On the other hand, control ex- 

 periments indicated that extracts from white adipose tissues such as omen- 

 tum or perinephric fat tissue from hibernating animals were inactive in 

 altering the respiratory metabolism. There are no tests to prove the na- 

 ture of this component of brown adipose tissue, or to demonstrate whether 

 or not the concentration varies in this tissue in hibernating and in non- 

 hibernating animals. These results do suggest that fat may play a greater 

 role in the regulation of the metabolic activities of the body by a humoral 

 mechanism than is currently realized. 



8. Lipid Storage under Abnormal Conditions 



Two different types of abnormal lipid deposition are well recognized. 

 In the first instance, excessive amounts of fat are stored in the usual fat de- 

 pots, with the result that obesity or adiposity occurs. Under these condi- 

 tions, the fatty deposits consist chiefly of triglyceride fat having the com- 

 position ordinarily noted for storage fats. The second type of abnormal 

 lipid deposition consists of an accumulation of non-glyceride lipids, usually 

 in specific organs, frequently with the result that the function of the af- 

 fected organ is impaired. In many cases, a considerable enlargement of the 

 particular organ involved also occurs. Cholesterol is the lipid most fre- 

 quently concerned with this type of abnormality, but sphingomyelin and 

 cerebrosides may be the specific lipids present in abnormal amounts. 



(1) Abnormal Deposition of Triglyceride Fats in General 



Although there are many different theories as to the cause of obesity, one 

 underlying fact is undisputed, namely, that this condition occurs only when 



490 D. Ferdmann and O. Feinschmidt, Ergeb. Biol., 8, 1-74 (1932). 



491 A. T. Rasmussen, Endocrinology, 6, 760-770 (1922). 



492 C. F. Wendt, Z. physiol. Chem., 249, iv (1937). 



493 W. E. Hook, Proc. Soc. Exptl. Biol. Med., 45, 37-40 (1940). 



