Intakes of dietary docosahexaenoic acid ethyl ester and egg phosphatidylcholine improve maze-learning ability in young and old mice

The effect of dietary docosahexaenoic acid (DHA) [22:6 (n-3)] ethyl ester (EE) and egg-phosphatidylcholine (PC) on maze-learning ability in young and old mice was studied. Male Crj:CD-1 mice aged either 3 wk or 14 mo were fed a diet containing 2 g DHA-EE/100 g diet plus 3 g palm oil/100 g diet (DHA-EE Group), 5 g egg-PC/100 g diet (egg-PC Group), 1 g DHA-EE/100 g diet plus 2.5 g egg-PC/100 g diet plus 1.5 g palm oil/100 g diet (DHA-EE + egg-PC Group) or 5 g palm oil/100 g diet (Control Group) for 5 mo. Maze-learning ability was assessed 4 mo after the start of the experiment. The time required to reach the maze exit and the number of times that a mouse strayed into blind alleys in the maze were measured in three trials every 4 d. In trial 2 of young mice, performed on d 4 after the first trial, the DHA-EE group required less (P < 0.05) time to reach the maze exit and DHA-EE and egg-PC groups strayed (P < 0.05) into blind alleys fewer times than the control group. In trial 2 of old mice, the DHA-EE, egg-PC and DHA-EE + egg-PC groups needed less (P < 0.05) time to find the exit and spent a fewer (P < 0.05) number of times in blind alleys than did the control group. The DHA-EE, DHA-EE + egg-PC and egg-PC groups strayed into blind alleys fewer times than the control group in trial 3 of old mice (P < 0.05). Our results suggest that the intake of DHA-EE and the egg-PC diet effectively enhances maze-learning ability and brain functions in old mice.