High-linoleate and high-alpha-linolenate diets affect learning ability andnatural behavior in SAMR1 mice

Semipurified diets incorporating either perilla oil [high in alpha-linolena te, 18:3(n-3)] or safflower oil [high in linoleate, 18:2(n-6)] were fed to senescence-resistant SAMR1 mouse dams and their pups. Male offspring at 15 mo were examined using behavioral tests. In the open field test, locomotor activity during a 5-min period was significantly higher in the safflower oi l group than in the perilla oil group. Observations of the circadian rhythm (48 h) of spontaneous motor activity indicated that the safflower oil grou p was more active than the perilla oil group during the first and second da rk periods. The total number of responses to positive and negative stimuli was higher in the safflower oil group than in the perilla oil group in the light and dark discrimination learning test, but the correct response ratio was lower in the safflower oil group. The difference in the (n-6)/(n-3) ra tios of the diets reflected the proportions of (n-6) polyunsaturated fatty acids, rather than those of (n-3) polyunsaturated fatty acids in the brain total fatty acids, and in the proportions of (n-6) and (n-3) polyunsaturate d fatty acids in the total polyunsaturated fatty acids of the brain phospho lipids. These results suggest that in SAMR1 mice, the dietary alpha-linolen ate/linoleate balance affects the (n-6)/(n-3) ratio of brain phospholipids, and this may modify emotional reactivity and learning ability.