Interactive effects of increased intake of saturated fat and cholesterol on atherosclerosis in the Japanese quail (Coturnix japonica)

Abstract

Increasing the energy value of diets with dietary fat, particularly fats rich in saturated fatty acids, can result in the elevation of plasma total and lipoprotein cholesterol. In the present study, experimental diets were designed to examine the effects of increasing the energy content of diets with a saturated fat source and cholesterol in a non-purified diet on hyperlipoproteinaemia and aortic plaque composition in the atherosclerosis-susceptible Japanese quail (Coturnix japonica) model of human atherosclerosis. Commercial poultry diets containing two levels (i.e. 60 or 120 g/kg) of beef tallow as the primary source of saturated fat were balanced for endogenous cholesterol or supplemented with cholesterol (i.e. 0.5 or 5.0 g/kg) and fed to quail for 9 weeks to examine the effects on whole plasma, lipoprotein and aortic plaque lipid composition in relation to aortic plaque formation. Hypercholesterolaemia (P < 0.001) aortic plaque deposition, which was further enhanced in birds fed on the 120 g/kg beef tallow-HC diet. Quail fed on 120g/kg beef tallow-HC diets exhibited the most severe aortic plaque formation, with marked increases in aortic tissue cholesterol content and quantifiable amounts of several cholesterol oxides (5,6α-epoxy-5α-cholesterol, 7β-hydroxycholesterol, cholestanetriol, 7-ketocholesterol and 25-hydroxycholesterol). In summary, hyperlipoproteinaemia associated with HC diets with a greater proportion of energy from saturated fat produced a combined effect in altering plasma and lipoprotein lipid composition as well as aortic tissue cholesterol and cholesterol oxide content in the Japanese quail.