Abstract
The effects of oleic acid on the concentrations of plasma lipids with special reference to the rates of lipid secretion from the liver were investigated in male Wistar rats. In Exp. 1, rats weighing about 90g were fed a test diet containing 15% (wt%) corn, high-oleic sunflower, sunflower, higholeic safflower or safflower oil for 2 weeks, and the lipid concentrations in the plasma and liver were determined. The concentrations of total cholesterol and triacylglycerol in the plasma of rats fed the high-oleic sunflower oil and high-oleic safflower oil diets were higher than those of rats given the corn oil, sunflower oil and safflower oil diets. The concentration of liver total cholesterol was low in rats fed the high-oleic sunflower oil diet and high in rats given the safflower oil diet, compared with that in rats fed the corn oil diet. Liver triacylglycerol concentrations were not different among the dietary groups. In Exp. 2, the rates of lipid secretion from the liver after Triton WR-1339 injection were estimated in rats fed the corn oil or high-oleic safflower oil diet for 2 weeks. The secretion rates of cholesterol and triacylglycerol in rats fed the high-oleic safflower oil diet were not different from those of rats given the corn oil diet. These results suggest that the elevation of plasma lipid concentrations in rats fed the diet rich in oleic acid is not directly related to the rate of lipid secretion from the liver.
