Behavioral deficits associated with dietary induction of decreased brain docosahexaenoic acid concentration

Docosahexaenoic acid (DHA), an n-3 fatty acid, is rapidly deposited during the period of rapid brain development. The influence of n-3 fatty acid defi ciency on learning performance in adult rats over two generations was inves tigated. Rats were fed either an n-3 fatty acid-adequate (n-3 Adq) or -defi cient (n-3 Def) diet for three generations (F1-F3). Levels of total brain n -3 fatty acids were reduced in the n-3 Def group by 83 and 87% in the F2 an d F3 generations, respectively. In the Morris water maze, the n-3 Def group showed a longer escape latency and delayed acquisition of this task compar ed with the n-3 Adq group in both generations. The acquisition and memory l evels of the n-3 Def group in the F3 generation seemed to be lower than tha t of the F2 generation. The 22:5n-6/22:6n-3 ratio in the frontal cortex and dams' milk was markedly increased in the n-3 Def group, and this ratio was significantly higher in the F3 generation compared with the F2 generation. These results suggest that learning and cognitive behavior are related to brain DHA status, which, in turn, is related to the levels of the milk/diet ary n-3 fatty acids.