Brain and heart membrane fatty acid composition in miniature swine fed diets containing corn and menhaden oils

Thirty-six female minipigs, from 4.7-10.6 years old, were fed corn oil (CO) and/or menhaden oil (MO) in diets containing 0, 0.75, or 15% MO and sufficient CO to provide 15% total oil for 6 months. Half the animals were made hypercholesterolemic by feeding them a 13% lard, 2% cholesterol diet for 2 months prior to the experimental feeding period. Samples were taken from the same location in each animal from forebrain, caudate nucleus, cerebellum, and heart to isolate brain synaptosomes and heart plasma membranes. Pretreatment of the minipigs with cholesterol had no effect on the fatty acid composition of the fractions isolated and their membrane fluidity. Despite MO feeding, the long chain n-3 fatty acids were low in the heart plasma membranes compared to heart tissue homogenates from the same animals. Minipigs fed 15% MO showed significant increases in synaptosomal eicosapentaenoate (EPA) and docosapentaenoate (DPA). Docosahexaenoate (DHA) was incorporated into synaptosomes in animals fed 0.75% MO, at concentrations significantly higher than in the CO-fed pigs. Rigs fed 15% MO showed significantly lower brain DHA than those fed CO. The synaptosomal data for the pigs fed the various diets suggest that metabolic synthesis from linolenate, 18:3(n-3), may be a more important source bf brain DHA than diet, but that dietary n-6/n-3 ratios and levels of 18:3(n-3), EPA, DPA and DHA may require careful attention. The fatty acid changes did not affect fluidity determined by fluorescence anisotropy of diphenylhexatriene or its polar derivatives. Published by Elsevier Science Inc.