Intravenous infusion of tridocosahexaenoyl-glycerol emulsion into rabbits effects on leukotriene B_4/5 production and fatty acid composition of plasma and leukocytes

Leukotriene (LT) B₄ is a major chemical activator of PMN. Inhibitory effects of oral administration of docosahexaenoic acid (DHA) on LTB₄ synthesis by PMN are known. We intravenously infused tridocosahexaenoyl-glycerol (DHA-TG) emulsion into rabbits in three different doses, namely 0.8, 0.4, or 0.2 g DHA/kg, and investigated the changes in LTB_4/5 production by ionophore-activated PMN. The averaged LTB₄ production by PMN was significantly reduced to 57 and 59% of baseline at 6 h after the infusion of 0.8 and 0.4 g DHA/kg, respectively (P < 0.05), but not after the infusion of 0.2 g DHA/kg or 0.8 g soybean oil/kg. The combined concentrations of both DHA and eicosapentaenoic acid in the PMN phospholipid fraction were significantly increased at 6 h after the infusion of 0.8 or 0.4 g DHA/kg but not after the infusion of 0.2 g DHA/kg or 0.8 g soybean oil/kg. Oral administration of 0.8 g DHA/kg did not increase DHA or eicosapentaenoic acid in the PMN phospholipid fraction and did not decrease LTB₄ production by PMN at 6 h after administration. We suggest that the infusion of 0.4-0.8 g DHA/kg might be beneficial to patients who suffer from diseases that are related to the acute elevation of LTB₄ production.