This study was designed to define the effect of
dietary restriction and
cholesterol feeding on disturbances of
very low density lipoprotein (VLDL) catabolism. Three groups of 15 New Zealand rabbits were fed standard or
cholesterol-rich diets either ad libitum or in restricted amounts and in vitro binding assays on hepatocyte membranes were carried out after 4, 8, 12 and 20 d.
Cholesterol feeding reduced the specific binding of labeled
beta-VLDL to liver membranes.
Dietary restriction, which enhances the
hypercholesterolemia induced by
cholesterol feeding, had no additional effect on the down-regulation of
beta-VLDL specific binding. In another set of experiments the uptake of labeled
beta-VLDL by various tissues was measured after 15 d of feeding the diets.
Cholesterol feeding decreased uptake of these
lipoproteins by the liver and various extrahepatic tissues, such as skin, intestine, muscle, adipose tissue, kidneys, spleen and aorta. Additional changes occurred in liver and intestine with
dietary restriction. In liver
beta-VLDL uptake in the group fed a restricted amount of the
cholesterol-containing diet was 70% of that in the group fed the same diet ad libitum. Taken together, the results suggest that
dietary restriction acts mainly on the receptor-independent catabolism of
beta-VLDL.