Brain and hippocampus fatty acid composition in phospholipid classes of aged-relative cognitive deficit rats.

The aim of this work was to study the composition of long chain fatty acids and the n-6 and n-3 fatty acid ratios in aged and young Wistar rats in brain and hippocampus, related to relative cognitive deficits. The aged animals showed cognitive deficits during acquisition of a memory task (delayed alternation). In brain, results showed a decrease in palmitoleic and palmitic acid percentages in all the studied phospholipid classes and in the phosphatidylserine and phosphatidylcholine classes, respectively, in old rats, compared to the young ones. There was also an increase in oleic and stearic acid amounts in the sphingomyelin, phosphatidylserine and phosphatidylinositol classes and in the phosphatidylserine and phosphatidylcholine classes, respectively. Arachidonic acid amount was decreased in old rats, compared to the young ones, in the phosphatidylserine and phosphatidylinositol classes. Total n-6 and n-3 fatty acid amounts were both decreased in all phospholipid classes, with a stable n-6/n-3 ratio. Our results confirm that arachidonic acid concentration is decreased in aged rats and that this reduction, more significant in phosphatidylserine and phosphatidylinositol classes, should be related to the fact that low concentrations of arachidonic acid are observed during activation of glutamate receptor.