Diets containing long-chain n-3 polyunsaturated fatty acids affect behaviour differently during development than ageing in mice

The effect of a standard diet providing essential fatty acids enriched in f ish oil or palm oil was studied in young, mature and old mice. Two groups o f pregnant and lactating OF1 mice were fed on diets with or without high le vels of long-chain n-3 polyunsaturated fatty acids. Offspring were maintain ed on these diets after weaning. The litter size did not differ. The weight increased more quickly in fish-oil-fed mice than palm-oil-fed mice. The fi sh-oil diet induced a significant increase in exploratory activity in young mice which was not found in mature and old mice. The level of locomotor ac tivity was significantly higher in young, no different in mature, and lower in old fish-oil-fed mice than in controls. Habituation, the simpler form o f learning, occurred to the same extent in the two diet groups. For the pla ce learning protocol of the Morris water maze there was no difference betwe en the two diet groups; however, in the probe trial, the mature fish-oil-fe d mice remembered the situation well compared with the control mice. In the active avoidance test, on the first day of acquisition the young fish-oil- fed mice made more avoidances than control mice, whereas in contrast, matur e and old-fish-fed mice made less avoidances than control mice. These resul ts suggest a positive effect on arousal and learning ability of a diet enri ched in long chain n-3 polyunsaturated fatty acids in young mice and a detr imental effect in old mice.