[Blood leukotriene B4 response to endotoxin in fish oil fed rats]

Six-week-old male Wistar rats were given a low fat diet containing 15% cod liver oil (FO; n = 30) or 15% safflower oil (SO; n = 30) for 6 weeks. In the polymorphonuclear leukocytes, arachidonic acid (AA) was significantly lower in the FO group than in the SO group (p < 0.001), and eicosapentaenoic acid (EPA) in the FO group was present in large amounts showing the EPA/AA ratio of 1.76. When lipopolysaccharide (LPS; 10mg/kg) was intraperitoneally injected, white blood cell counts in the blood significantly decreased in both groups (p < 0.001) compared to the controls 2 hours later, and at 4 hours, the counts in the SO group (2,033 +/- 151/mm3) were lower than in the FO group (3,189 +/- 624/mm3), (p < 0.01). In both groups, leukotriene B4 (LTB4) in the whole blood increased at 4 hours following LPS-administration compared to the controls (1,219 +/- 167.3pg/ml in the SO group and 600.0 +/- 109.0pg/ml in the FO group, p < 0.001). It should be noted that the level of LTB4 in the SO group was significantly higher than in the FO group (p < 0.001). Changes of the metabolites including decreased LTB4 production in the arachidonic cascade related to the increase of EPA may play a role in the inhibition of the decrease in white blood cell counts.