Influence of Dietary Triacylglycerol Structure and Level of n–3 Fatty Acids Administered during Development on Brain Phospholipids and Memory and Learning Ability of Rats

Abstract

Objective: The objective of this study was to examine the effects of triacylglycerol (TAG) structure and level of n–3 fatty acids on fatty acid profile of brain phospholipids (PL) of dams and offspring, and the memory and learning ability of the offspring, when administered during initial development of the nervous system. Methods: Pregnant rats were fed experimental diets from the 8th day of pregnancy throughout lactation. After weaning and until 13 weeks of age, the pups were fed the same diet as their dams. The experimental diets contained either a structured oil, a linseed oil, or a fish oil. In the structured oil, α-linolenic acid (18:3n–3) was predominantly located in the sn-2 position of the triacylglycerols and the level of 18:3n–3 was 2 mol or 10 mol%. In the linseed oil diets the level of 18:3n–3 was 2 mol or 10 mol% as well. Finally, the fish oil diet contained 18:3n–3 as well as 20:5n–3 and 22:6n–3 adding up to a total of 2 mol% n–3 fatty acids. The effects of the experimental diets were compared to the effect of a chow diet. Results: The amount of 22:6n–3 in brain phosphatidyl ethanolamine (PE) and phosphatidyl serine (PS) of dams and offspring (3 and 13 weeks of age) was not affected by the six different diets. 18:2n–6, but not 18:3n–3, was detected in brain PL, suggesting a specificity of the tissues in the metabolism of n–3 and n–6 fatty acids. The level of monounsaturated fatty acids (MUFA) increased with increasing age of the pups, indicating an enhanced myelinization. No considerable differences between groups were found when memory or learning was tested in the Morris water maze. Conclusion: The results suggest that extreme diet modifications are needed in order to observe significant effects on the memory and learning ability in rats.