6o 



Scientific Proceedings (71). 



35 (1099) 



Observations on cholesterol-fed guinea pigs. 



By C. H. Bailey, M.D. (by invitation). 



[From the Pathological Laboratory of Stanford University Medical 



School.] 



The following experiments were done to test the possibility 

 of the production of atheroma of the aorta in guinea pigs by cho- 

 lesterol feeding, and also to test certain theories which have been 

 advanced as to the importance of factors, other than the cholesterol, 

 in the production of this type of atheroma. 



Four guinea pigs were fed on daily doses of 0.1 to 0.5 gm. of 

 cholesterol dissolved in cotton seed oil for periods of 18 to 72 days. 

 These animals, like rabbits similarly fed, show an enlargement of 

 the adrenals, and an abundant deposit of anisotropic fat in the 

 liver and spleen, the situation of this fat being similar to that 

 previously described in these organs in the rabbit. An occasional 

 guinea pig in this and the following experiments showed focal 

 areas of degeneration in the cortex of the adrenal with a deposit 

 of calcium. The aortas show no gross lesions. Microscopically 

 there are found small patches of fatty infiltration in the intima 

 and upper media. The characteristic proliferation and subsequent 

 degeneration seen in the rabbit were entirely lacking. The feeding 

 periods were too short to conclude that such tissue reaction might 

 not ultimately result. One guinea pig which received 20 g. of 

 cholesterol in 72 days (15.1 g. in the last 40 days) would seem 

 however quite comparable with a rabbit, previously reported, 

 which showed pronounced atheroma after receiving 13.7 g. in 

 37 days. From these experiments and others which follow it 

 can at least be concluded that a longer period and larger doses 

 are necessary for the production of an atheroma in the guinea pig 

 than in the rabbit. 



A guinea pig receiving 13.4 g. cholesterol without oil in 51 days 

 showed some adrenal enlargement, but no anisotropic fat could 

 be found in liver, spleen, or elsewhere. Knack, because of failure 

 to produce atheroma in a rabbit with cholesterol alone, concludes 

 that previous injury to the aorta is necessary before a deposit of 



