Depletion of aortic free and ester cholesterol by dietary means in rhesus monkeys with fatty streaks

This report presents findings concerning free and esterified cholesterol and specific fatty acids esterified to cholesterol in aortas of rhesus monkeys fed an atherogenic diet for 12 weeks followed by regression regimen for 32 and 64 weeks. Mean aortic total cholesterol of monkeys fed an atherogenic diet was more than twice that of the animals on a control diet. Esterified cholesterol showed a fourfold elevation while increase in free cholesterol was less than twofold. Free cholesterol and esterified cholesterol in the aorta of animals decreased by about 30% and 70 respectively after 32 weeks on the regression diet. Very little additional changes occurred in the animals on the regression regimen for 64 weeks. In fatty acids esterified to cholesterol, the largest proportional increase was in stearic (18:0) and oleic (18:1) acids and the least proportional increase was in linoleic (18:2) and arachidonic (20:4) acids after 12 weeks on the atherogenic diet. As a result of feeding the regression diet for a period of 32 weeks an overall depletion of about 85% was observed from the levels in animals fed only an atherogenic diet. Cholesteryl stearate and oleate returned to near baseline levels with a reduction of about 90% from levels observed after feeding the atherogenic diet.