Effect of increasing the dietary (n-3) to (n-6) polyunsaturated fatty acid ratio on murine liver and peritoneal cell fatty acids and eicosanoid formation

An incremental increase in the dietary (n-3):(n-6) polyunsaturated fatty acid (PUFA) ratio from 0 to 1.93 in diets containing 15% fat (wt/wt) decreased the total (n-6) PUFA content of phospholipids of the liver and peritoneal cells (macrophage) in mice from 43.1 and 33.6 mol/100 mol to 16.0 and 12.3 mol/100 mol with a concomitant increase of 27.6 and 16.1 mol/100 mol in (n-3) PUFA, respectively. Consumption of (n-3) PUFA increased hepatic (n-3) PUFA levels without changing total PUFA (46.35 vs. 46.87 mol/100 mol), whereas macrophage PUFA levels were decreased. The synthesis of sulfidopeptide leukotrienes (SP-LT) (LTC₄ and LTE₄) was progressively reduced by increasing dietary (n-3) PUFA, i.e., there was a reduction of 76% in mice fed a diet containing a (n-3):(n-6) PUFA ratio of 1.93 compared with the control diet. The 5-series SP-LT (LTC₅) and LTF₅) were produced in all animals consuming (n-3) PUFA and accounted for 62% of all SP-LT synthesized in mice fed the diet containing a 1.93 (n-3): (n-6) PUFA ratio. Synthesis of 6-keto-prostaglandin F(1α) decreased 81% in mice fed a diet containing a (n-3):(n-6) PUFA ratio of 1.93 whereas prostaglandin E:2 synthesis decreased 44% in mice fed diets with (n-3):(n-6) ratios ranging from 0.41 to 1.93.