SMALL CHANGES OF DIETARY (N-6) AND (N-3) FATTY-ACID CONTENT RATIO ALTER PHOSPHATIDYLETHANOLAMINE AND PHOSPHATIDYLCHOLINE FATTY-ACID COMPOSITION DURING DEVELOPMENT OF NEURONAL AND GLIAL-CELLS IN RATS

It has been suggested that the fat composition of infant formula shoul d provide arachidonic acid [20:4(n-6)] and docosahexaenoic acid [22:6( n-3)] or increased alpha-linolenic acid [18:3(n-3)] to optimize the (n -3) and (n-6) fatty acid content of brain during infant development. T his experiment examined the effects of feeding increased levels of 13: 3(n-3), 20:4(n-6) and 22:6(n-3) on brain development in neonatal rats. Diets varying in (n-6) and (n-3) fatty acid content with or without 2 0:4(n-6) or 22:6(n-3), at levels proposed for infant formula, were fed to nursing dams from parturition and subsequently to weaned pups unti l 6 wk of age. Neuronal and glial cells were isolated from the frontal region, cerebellum and hippocampus of the brain. Fatty acid analyses of ethanolamine- and choline-phosphoglycerides indicated that small ch anges in the dietary (n-6)/(n-3) ratio significantly altered neuronal and glial membrane fatty acid composition. Brain regions and cell type s varied in amount and rate of 20:4(n-6) and 22:6(n-3) accretion. Fatt y acid composition of individual phosphoglycerides was distinct and ex hibited changes with age. Inclusion of both 20:4(n-6) and 22:6(n-3) in the diet resulted in alteration of brain fatty acid composition refle cting the fatty acid composition of the diet. If analogous development al changes occur in human brain, then these results imply that additio n of 20:4(n-6) and 22:6(n-3) or a reduced 18:2(n-6):18:3(n-3) ratio in infant formula may result in fatty acid profiles of neuronal and glia l cells in formula-fed infants similar to those observed in breastfed infants.