Effect of Intake of Dried Mackerel on Brain Fatty Acid Composition and Passive Avoidance Performance

This study attempts to determine the effect of feeding mackerel dried by low temperature vacuum method to mice on their learning behavior and fatty acid composition of the nervous system. Thirty-two male mice were fed either a control (palm oil, control group) diet or a diet of 20% dried mackerel (mackerel group) for three months. Learning behavior was assessed using a passive avoidance test, and the tissue fatty acid composition was measured after the behavioral test. The lack of experience with electronic foot shocks resulted in both the control and mackerel groups showing shorter latency during the acquisition trial (Day 1). The avoidance latencies of each group subsequently increased after multiple acquisition trials. The mackerel group showed a significantly longer avoidance latency on day 2 than was the case with the control group (p <0.05). In terms of the fatty acid composition of the serum and nervous tissues such as the brain and retina, the mackerel group showed increased percentages of total n-3 fatty acids, and especially docosahexaenoic (DHA) and eicosapentaenoic (EPA) acids. Meanwhile, the control group showed decreased DHA levels, but increased docosapentaenoic acid (DPAn-6) levels. From the above results, it may be concluded that the intake of mackerel dried by low temperature vacuum improved learning behavior, as assessed by passive avoidance test, with increased DHA in the brain.