Extravascular lipid deposition and morphology of atherosclerosis in heterozygous WHHL rabbits fed vegetable (n-6) and marine (11-3) oils

Abstract

The aim of this experiment was to test the cholesterol-fed heterozugous WHHL rabbit as a model for investigation of atherogenicity of different fats. Twentytwo rabbits of both sexes, 8—9.5 months old were randomized in 3 groups, and fed 100 g diet daily: cholesterol enriched standard diet (group I, n=8), cholesterol enriched diet with added vegetable (group II, n=7). or marine (group III, n=7) oils during 14 weeks. The vegetable oil (n-6 = 33 %, n—3 less than 1 %) and a marine oil
(n-6 = 18 %, n-3 = 17 %) were adjusted to contain equal amounts of saturated and monounsaturated fatty acids. One percent cholesterol in the diet caused a pronounced hypercholesterolemia which was significantly enhanced by addition of oils.
The increase in total cholesterol was especially reflected in the increase in the VLDL concentration. The blood cholesterol and triglyceride levels were comparable between the two of fed groups apart from a transitory lowering in the marine oil
fed rabbits. The atherosclerotie lesions caused by 1 % cholesterol in the diet were fibrous plaques and plaques with foam cells. The added oils aggravated the atherosclerosis caused by cholesterol. Based on morphological appearance of the aortic
and coronary atherosclerosis the marine oil was more atherogcnic than the vegetable oil. In pulmonary arteries, however, the less severe atherosclerotic changes were found in the marine oil group. In this group no lipid infiltrations were seen in the myocardium but very severe infiltrations were seen in the liver. In the vegetable oil group these infiltrations were severe in the myocardium and less pronounced in the liver. The massive hypereholesterolemia and extravascular lipid deposition in different parenchymatous organs suggest that lower doses of dietary cholesterol should be used when the cholesterol-fed heterozygous WHHL rabbit is chosen to study the ellect ot'van'ous fats on blood lipids and development
of atherosclerosis.