Water maze performance is unaffected in artificially reared rats fed dietssupplemented with arachidonic acid and docosahexaenoic acid

Four groups of male Long-Evans rats were reared artificially from postnatal d 5 to 18 by being fed through a gastrostomy tube with rat milk substitute s containing oils providing 10% linoleic acid and 1% alpha-linolenic acid ( g/100 g fat); with the use of a 2 x 2 design, they were fed one of two leve ls of arachidonic acid (AA) and docosahexaenoic acid (DHA) (0.0 and 2.5 g/1 00 g of fatty acids). A fifth artificially reared group was fed a diet high in saturated fat, and a sixth group was reared by dams fed a standard AIN- 93M diet. The pups were weaned onto modified AIN-93G diets, with a fat comp osition similar to that fed during the artificial rearing period. Behaviora l testing was conducted between 6 and 9 wk of age; brain lipid composition was then assessed. Relative to the unsupplemented group (0.0 g/100 g AA and DHA), dietary supplementation resulted in a wide range of AA (84-103%) and particularly DHA (86-119%) levels in forebrain membrane phospholipids. AA supplementation increased AA levels and decreased DHA levels, and DHA suppl ementation increased DHA levels and decreased AA levels, with the magnitude of these effects dependent on the level of the other fatty acid. DHA level s were very low in the saturated fat group. The groups did not differ on th e place or cued version of the Morris water-maze, but on a test of working memory, the saturated fat group was impaired relative to the suckled contro l group. Further correlational analyses in the artificially reared animals did not support a relationship between the wide range of DHA and AA levels in the forebrain and working-memory performance.