The influence of exogenous cholesterol on hepatic lipid composition of the rat*

Abstract

Rats were fed diets containing cottonseed oil and/or cholesterol, cholic acid, methyl esters of long-chain fatty acids, and tocopherol. Livers, hearts, and aortas were examined histologically; liver lipids were fractionated by silicic acid chromatography; and the fatty acid composition of the sterol esters, triglycerides, and phospholipids was determined by gas-liquid chromatography. The degree of deposition of liver sterol esters seemed to be related to the availability of dietary fatty acids for esterification with exogenous cholesterol. No differences in sterol ester deposition were noted among the groups in which the dietary cholesterol was supplemented with methyl esters of fatty acids of different degrees of unsaturation. Fatty acid analysis revealed an accentuation by cholesterol feeding of the increase in monoenoic fatty acids and the decrease of linoleic and arachidonic acids characteristic of essential fatty acid deficiency. Two eicosatrienoic acids, occurring primarily in the phospholipids, were identified. The 5,8,11-eicosatrienoic acid appears to be related to essential fatty acid deficiency, whereas the 8,11,14-isomer is probably an intermediate in the conversion of linoleic to arachidonic acid and is increased when exogenous cholesterol induces an increased arachidonic acid synthesis.