This study investigated the effects of varying dietary levels of n-6:n-3 fatty acid ratio on plasma fatty acid composition and prostanoid synthesis in pregnant rats. Four groups consisting of seven rats pergroup of non pregnant rats were fed diets with either a very low n-6:n-3 ratio of 50% soybean oil (SBO): 50% cod liver oil (CLO) 1:1 group , a low ratio of 84% SBO: 16% CLO 6:1 group, a high ratio of 96% SBO: 4% CLO 30:1 group and control group was given only rat chow diet. Blood samples were taken at day 15 post mating and the plasma was analyzed for fatty acid profile, specifically the n-6:n-3 fatty acid ratio and prostaglandins F2α and E2. The n-3 polyunsaturated fatty acids (PUFA) in plasma of group 1:1 were significantly (P < 0.05) higher than the other groups, while the n-6:n-3 fatty acid ratio was significantly lower. The total n-6 PUFA was significantly higher (P < 0.05) in group 30:1 as compared to the control and 1:1 groups. The total PGF2α and PGE2 were significantly higher (P < 0.05) in group 30:1 rats fed a diet high in n-6 or n-6:n-3 fatty acids. The diet higher in n-6 fatty acids appear to increase arachidonic acid( AA) and prostaglandins synthesis in plasma of rats. PGE2 productions in plasma were significantly lower in rats fed diets with a lower dietary ratio of n-6:n-3 fatty acids than in those fed diets with a higher dietary ratio. Regression analysis revealed a significant positivecorrelation between PGF2α and PGE2 and the ratio of n-6:n-3, and significant positive correlation between different ratio n-6:n-3 on fatty acid plasma compstion and PGF2α and PGE2 concentration on plasma. These results demonstrated that the dietary ratio of n-6:n-3 modulates PGF2α and PGE2 production. The n-6:n-3 fatty acid ratio significantly affected plasma fatty acids profile and prostaglandin synthesis in pregnant rat.Keywords: n-6:n-3 fatty acid ratio, plasma fatty acids, prostanoid synthesis, pregnant ra
