INFLUENCE OF DIETARY-CHOLESTEROL AND FAT SOURCE ON ATHEROSCLEROSIS INTHE JAPANESE-QUAIL (COTURNIX JAPONICA)

The Japanese quail has been used as a model of human atherosclerosis t o investigate the mechanisms underlying the development of vascular le sions, i.e. hyperlipoproteinaemia and impaired endogenous antioxidant status, In the present study, Japanese quail were fed on semipurified diets containing butter, beef tallow or soyabean-oil blends, with eith er 0.5 or 5 g cholesterol/ kg for 9 weeks to examine the effects of di etary fat blends varying in fatty acid composition and cholesterol int ake on plasma lipids and aortic atherosclerotic plaque and sterol comp osition, These findings were related to possible diet-induced changes in antioxidant status of selected tissues, Hypercholesterolaemia was c onfirmed (P < 0.001) in birds fed on high-cholesterol (HC) diets, Plas ma total cholesterol concentration and cholesterol content of lipoprot ein fractions in hypercholesterolaemic birds were lower (P < 0.05) in quail fed on the soyabean-oil blend, Plasma triacylglycerol content wa s increased (P < 0.001) in HC-fed birds, Dietary fat blends did not in fluence plasma triacylglycerol levels, Tissue antioxidant status (cata lase (EC 1.11.1.6), glutathione peroxidase (EC 1.11.1.9), glutathione reductase (EC 1.6.4.1) and superoxide dismutase (EC 1.15.1.1) activiti es and glutathione content) was generally not greatly affected by diet ary fat blend or cholesterol treatment, Birds fed on HC diets exhibite d severe (P < 0.001) atherosclerotic plaque in aortas which was not in fluenced by the source of dietary fat blend, Scanning electron microsc opy confirmed results of visual aortic plaque scoring using dissecting light microscopy, Several cholesterol oxides were identified and quan tified in aortic plaque from HC-fed birds (5,6 alpha-epoxy-5 alpha-cho lesterol, 7 beta-hydroxycholesterol and 7-ketocholesterol) regardless of dietary fat blend. The results indicate that dietary fat blends var ying in polyunsaturated: saturated fatty acid ratios only marginally i nfluence the degree of hypercholesterolaemia in atherosclerosis-suscep tible quail fed on atherogenic diets only, and are not a factor, compa red with sterol feeding, in modulating the degree of atherosclerosis o r the aortic oxysterol content in these same birds, Moreover, diet-ind uced hyperlipoproteinaemia had only a small effect on antioxidant stat us of selected tissues examined.