Effect of lipids extracted from a salted herring roe food product on maze-behavior in mice

Male mice (11 mo old) were fed 5% lard, fish oil, or Kazunoko (salted fish roe product) lipids for 4 mo to investigate their effects on maze behavior. The time required and distance traveled to reach the maze exit, and number of times that a mouse strayed into blind alleys in the maze, and the fatty acid compositions of brain lipids after the maze-behavior experiment were measured. The Kazunoko lipid group showed a significant improvement in all three parameters compared with the lard diet group, but the fish oil group showed only a significant decrease in the number of times that a mouse strayed into blind alleys compared with the lard diet group. The mice in the fish oil and Kazunoko lipid groups had significantly lower levels of arachidonic acid and higher percentages of docosahexaenoic acid in brain lipids compared with animals in the lard group. The mice in the Kazunoko lipid group had significantly lower levels of arachidonic acid in brain lipids than those in the fish oil group but the percentages of docosahexaenoic acid were not significantly different between these two diet groups. Our results suggest that an intake of Kazunoko lipids may suppress the percentage of n-6 fatty acids in brain lipids and this diet can be even more effective than fish oil as a supplement to improve learning capacity in mice.