Effect of dietary (n-9) eicosatrnoic acid on rat leucocyte fatty acid composition and eicosanoid production

Abstract

Eicosatrienoic acid (ETrA) is the (n-9) homologue of (n-6) arachidonic acid (AA) and (n-3) eicosapentaenoic acid (EPA). ETrA can be synthesised endogeneously but tissue levels are normally very low except in essential fatty acid (EFA) deficiency. Like AA and EPA, ETrA can be incorporated into cell membranes, whence it may compete for access to eicosanoid forming enzymes. A study was undertaken in rats to examine incorporation into leucocytes of dietary ETrA. Diets were EFA sufficient. The effect of dietary linoleic acid (LA) on ETrA accumulation in cells was studied and correlations with eicosanoid production sought. ETrA was incorporated into peritoneal exudate cells (PEC) with no evident saturation being observed with levels up to 10% of total fatty acids in PEC phospholipids. Dietary LA partially reduced the incorporation of dietary ETrA into cells. ETrA accumulation in PEC correlated with reduced LTB4 synthesis which was attributable to inhibition of LTA hydrolase. Thus, dietary ETrA can acccumulate in leucocytes and suppress inflammatory eicosanoid synthesis.