Modulation of fatty acid composition in murine brain by dietary unsaturated fats

Abstract

The response of individual phospholipid class fatty acid composition to dietary fats was studied in murine brain. Purified diets containing 10% (by weight) safflower oil, olive oil, linseed oil, or a mix of 9:1 (wt/wt) fish oil/safflower oil were fed to female mice. Offspring continued on the diets and were sacrificed on 3, 18, and 42 days after parturition. Docosahexaenoic acid (DHA;22:6n-3), abundant in the fish oil fed group, was particularly enriched in phosphatidyl ethanolamine and phosphatidyl serine. Fish oil-fed mice accumulated more DHA than the linseed oil-fed mice. While olive oil contained just 0.6% n-3 PUFA, DHA levels in linseed oil-fed animals overall were only slightly higher than olive oil-fed mice and were only elevated in the phospholipids classes phosphatidyl ethanolamine and phosphatidyl inositol. By contrast, DHA levels in the safflower oil-fed group were dramatically lower, containing instead elevated levels of 22:4n-6 and 22:5n-6. Eicosapentaenoic acid (EPA; 20:5n-3) levels were significantly lower in the brain relative to the other tissues we examined, implying that this fatty acid was selectively excluded from the brain or immediately metabolized to DHA in the brain. The amount of EPA in the brain was independent of the form of n-3 fatty acids in the diet, whereas DHA levels were strongly dependent. The type of n-3 PUFA was more important to 22:6n-3 accumulation in brain than the absolute quantity of 18:3n-3 and the vast majority of n-3 accumulation in all lipid classes examined occurred prior to weaning.