Gene expression and molecular composition of phospholipids in rat brain in relation to dietary n-6 to n-3 fatty acid ratio.

Rats were fed from conception till adulthood either with normal rat chow with a linoleic (LA) to linolenic acid (LNA) ratio of 8.2:1 or a rat chow supplemented with a mixture of perilla and soy bean oil giving a ratio of LA to LNA of 4.7:1. Fat content of the feed was 5%. Fatty acid and molecular species composition of ethanolamine phosphoglyceride was determined. Effect of this diet on gene expression was also studied. There was an accumulation of docosahexaenoic (DHA) and arachidonic acids (AA) in brains of the experimental animals. Changes in the ratio sn-1 saturated, sn-2 docosahexaenoic to sn-1 monounsaturated, sn-2 docosahexaenoic were observed. Twenty genes were found overexpressed in response to the 4.7:1 mixture diet and four were found down-regulated compared to normal rat chow. Among them were the genes related to energy household, lipid metabolism and respiration. The degree of up-regulation exceeded that observed with perilla with a ratio of LA to LNA 8.2:1 [Proc. Natl. Acad. Sci. U. S. A. 99 (2002) 2619]. It was concluded that brain sensitively reacts to the fatty acid composition of the diet. It was suggested that alteration in membrane architecture and function coupled with alterations in gene expression profiles may contribute to the observed beneficial impact of n-3 type polyunsaturated fatty acids on cognitive functions.