Early dietary intervention with structured triacylglycerols containing docosahexaenoic acid. Effect on brain, liver, and adipose tissue lipids

Abstract

Newborn rats were fed liquid diets containing 7 wt% fat in which 3.8% of the total fatty acids were 22:6n-3. The fats were either a specific structured oil with 22:6n-3 mostly located in the sn-2 position or a randomized oil with 22:6n-3 equally distributed in the triacylglycerol (TAG) molecules. The oils were manufactured by interesterification of fish oil TAG with free fatty acids from butterfat. The pups were tube-fed three times a day and stayed with their dams during the night. After 14 d they were fed solid diets containing the same oils for the next 7 d. A reference group stayed with the dams and received ordinary rat chow at weaning. In general no significant differences between the two dietary treatments were observed in the tissues examined except for adipose tissue. The levels of 22:6n-3 were significantly increased in brain phosphatidylcholines (PC) and phosphatidylserines (PS) of both experimental groups compared with the reference group after three weeks, whereas no differences were found in brain phosphatidylethanolamines (PE) and phosphatidylinositols (PI). In all groups and all phospholipids examined, the levels of 20:4n-6 generally decreased from 1 to 3 wk and were significantly lower in the experimental groups compared with the reference group at 3 wk except for PI. In liver, PC and PE 22:6n-3 remained constant in the experimental groups but decreased significantly in the reference group, whereas in liver PS 22:6n-3 increased in all groups, but reached significantly higher levels in the experimental groups than in the reference group. In adipose tissue, 22:6n-3 increased in the experimental groups during the study period, but decreased in the reference group, suggesting that a surplus of dietary 22:6n-3 was stored.