Changes of plasma lipids and long-chain n-3 and n-6 fatty acids in plasma, liver, heart and kidney phospholipids of rats fed variable levels of fish oil with or without cholesterol supplementation.

ABSTRACT

Diets supplemented with 10% by weight of oil, either wholly safflower oil or proportinally (25, 50, 75 or 100%) replaced by fish oil, were given to 60 rats which had previously been deprived of dietary fat for 6 weeks. Half the animals on each dietary regimen were also given 1% of cholesterol. After 4 weeks of feeding, the plasma lipid contents and the phospholipid fatty acid compositions of plasma, liver, heart and kidney were determined. In general, the concentrations of plasma lipids were significantly reduced in animals fed a diet containing 5% or more of fish oil in comparison with those fed only safflower oil. Cholesterol feeding increased the levels of plasma cholesterol, whereas it lowered those of plasma triacylglycerols and phospholipids. The levels of 204(n - 6) in all four tissues were sharply reduced, whereas those of 182(n - 6) increased when 25% of dietary safflower oil was replaced by fish oil. Both 182(n - 6) and 204(n - 6) were decreased as the contents of dietary fish oil were further increased. The levels of long-chain n-3 fatty acids, e.g., 205(n - 3), 225(n - 3) and 226(n - 3) were increased as the intake of fish oil increased. The incorporation of 226(n - 3) was greater in plasma, liver and heart phospholipids, whereas that of 205(n - 3) was greater in kidney phospholipids. Cholesterol feeding also increased the levels of 182(n - 6) and 205(n - 3), whereas it decreased the levels of 204(n - 6) and 226(n - 3) in plasma and liver. However, these changes were not observed in heart and kidney.