630 VI. OCCURRENCE OF LIPIDS IN THE ANIMAL 



that the metabolism is actually diminished as a result of injury to this por- 

 tion of the brain. This can be demonstrated when the metabolism tests are 

 made shortly after the operation, before an appreciable weight gain occurs, 

 or in animals on a limited food intake, so that the excessive body weight is 

 prevented. 532534 However, it was concluded by Brobeck 380 that "quanti- 

 tatively the amount of energy made available for extra storage by the re- 

 duced heat production is almost insignificant in contrast to the huge excess 

 ordinarily taken in as food." The most complete review of the subject of 

 the obesity resulting from hypothalamic lesions is that of Brobeck. 380 



(c) Obesity Resulting from the Injection of Gold-Thioglucose. Brecher 

 and Waxier 536 were the first to call attention to the fact that obesity may be 

 produced, in stock albino mice, by a single injection of gold salt of thio- 

 glucose. This is an unstable hydroscopic compound containing approxi- 

 mately 50% of gold. The weight gains were shown to be due to an in- 

 creased proportion of adipose tissue. It was later demonstrated 537 that 

 the increased fat deposition resulted from an augmented food intake. 

 Owen, Parson, and Crispell 538 suggest that this type of obesity may result 

 from serious interference with the "satiety mechanism," and may be as- 

 sociated with less serious effects on the "hunger mechanism," as has been 

 postulated in the case of experimental hypothalamic obesity. It is sug- 

 gested that the obesity resulting from gold-thioglucose may be mediated 

 through hypothalamic dysfunction. 



b. Obesity Resulting from Reduced Basal Metabolism. Although an 

 increased food intake may account for a large proportion of the incidence of 

 obesity, this condition may frequently arise from a reduced metabolic rate 

 coupled with a normal food intake. The tendency toward the deposition 

 of fat in myxedema and other types of hypothyroidism is an excellent ex- 

 ample of this kind of obesity. A decrease in basal metabolism may like- 

 wise occur, following castration, or after the menopause, which may be a 

 contributing factor in increasing fat deposition. Finally, the reduction of 

 the basal metabolism which is a normal concomitant of increasing age (after 

 puberty) may likewise play an important role in bringing about the in- 

 creased body weight frequently occurring in older individuals. 



c. Obesity Resulting from Reduced Activity. Ingle 539 reported that 

 obesity can readily be produced in rats by restriction of their activity. 

 Under these conditions, the development of obesity is related to the level 



536 G. Brecher and S. H. Waxier, Proc. Soc. Exptl. Biol. Med., 70, 498-501 (1949). 



537 S. H. Waxier and G. Brecher, Am. J. Physiol., 162, 428-433 (1950). 



538 J. A. Owen, Jr., W. Parson, and K. R. Crispell, Metabolism, 2, 362-366 (1953). 



539 D. J. Ingle, Proc. Soc. Exptl. Biol. Med., 72, 604-605 (1949). 



