Increases in hyperlipoproteinemia, disturbances in cholesterol metabolism and atherosclerosis induced by dietary restriction in rabbits fed a cholesterol-rich diet.

The influence of dietary restriction on cholesterol transport and metabolism was investigated in rabbits given standard or cholesterol-rich diets (0.2 g cholesterol/kg body weight daily) either ad libitum or with 50% caloric ration. Dietary restriction which has only a slight influence in control rabbits markedly aggravated the disturbances induced by exogenous cholesterol. With limited feeding, control rabbits presented a moderate increase in plasma cholesterol, whereas marked aggravation of hypercholesterolemia was observed in cholesterol-fed rabbits. Analysis of the lipoprotein profile showed that the excess of plasma cholesterol with the restricted cholesterol-rich diet corresponded to an increase in the concentration of very low density lipoprotein (VLDL) and low density lipoproteins (LDL) without any additional changes in the composition of these lipoproteins. No significant change appeared in the high density lipoprotein (HDL) concentration. The parameters of cholesterol metabolism were determined, from the curves of [3H]cholesterol radioactivity decrease, using a two-pool model. The increase in cholesterol turnover rate induced by the cholesterol-rich diet was accentuated by dietary restriction, whereas rabbits on standard restricted diet showed a slight decrease. The large increase in the size of both pools A and B in cholesterol-fed rabbits was even more pronounced with limited feeding. Dietary restriction induced additional accumulation of cholesterol in the aortic wall and the grade of the lesions was also aggravated.