CYCLIC VS CONTINUOUS ENTERAL FEEDING WITH OMEGA-3 AND GAMMA-LINOLENICFATTY-ACIDS - EFFECTS ON MODULATION OF PHOSPHOLIPID FATTY-ACIDS IN RAT LUNG AND LIVER IMMUNE CELLS

Background: Arachidonic acid (AA) present in lung and liver immune cel l phospholipids is the precursor of eicosanoids that promote neutrophi l margination, leading to tissue injury and inflammation. Administrati on of novel enteral formulations low in linoleic acid (LA) and contain ing eicosapentaenoic acid (EPA) from fish oil and gamma-linolenic acid (GLA) from borage oil displaces AA and promotes cell formation of eic osanoids with reduced inflammatory potential. The present study was un dertaken to determine whether or not shortterm provision of enteral di ets containing GLA, EPA, or both in a cyclic fashion modulated the fat ty acid composition of rat alveolar macrophage (AM) and liver Kupffer and endothelial (K&E) cell phospholipids in vivo to the extent achieve d during continuous feeding. Methods: Rats were isocalorically fed thr ough a gastrostomy catheter for 3 or 6 days with high-fat, low-carbohy drate diets that were enriched with either LA (diet A), EPA (diet B), or EPA + GLA (diet C). The rats were randomized by infusion modality, ie, continuous vs cyclic (14 hours feeding with 10 hours fasting daily ) feeding. AM and K&E were isolated and phospholipid fatty acid profil es were determined by gas chromatography. Results: The dietary effects on AM and K&E cell phospholipid fatty acids for a given feeding perio d were not significantly influenced by the infusion modality. AM and K &E cells from rats receiving either diet B or diet C for 3 days had si gnificantly lower AA and LA and higher EPA and dihomo-GLA (DHGLA), res pectively, than rats given diet A regardless of the infusion modality. The mole % of EPA and DHGLA in K&E cells were higher after 6 vs 3 day s of cyclic feeding with diet C. Using the eicosanoid precursor ratio (EPA + DHGLA/AA), the potential for generation of AA-derived eicosanoi ds was lower in rats given diet B or C vs diet A regardless of infusio n modality. Discussion: Given the rapid changes in lung and liver immu ne cell phospholipid fatty acids, shortterm provision of EPA and GLA-e nriched diets cyclically or continuously may prove clinically relevant for modulating the fatty acid composition and potential eicosanoid fo rmation by these cells.