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Alterations in canine plasma lipoproteins and lecithin: cholesterol acyltransferase activities during fish oil supplementation
Abstract
In an effort to better understand lipid metabolism in an atherogenic resistant species, effects of n-3 fatty acid rich fish oil on canine lipoproteins and lecithin:cholesterol acyltransferase (LCAT) activities were investigated. Adult, mixed-breed dogs were fed a diet moderately restricted in protein/phosphorus, relatively higher in fat, and supplemented with either safflower (SFO) or menhaden fish oil (MHO) capsules (I.Og/300kcal/day for adult maintenance). Plasma was collected initially, after diet acclimation, and after 22 days supplementation. Significant elevations of total, free, and esterified cholesterol concentrations occurred during acclimation to the high fat diet. Plasma triacylglycerol concentrations remained within normal limits. Lipoprotein cholesterol concentrations rose during diet acclimation in the ci-I and a-2 fractions. The SFO group experienced significant increases in the cl-2 lipoprotein fractions during SFO supplementation, whereas the MHO group was unchanged. Increased plasma LCAT activities were seen with increased dietary fat; oil supplements did not modify this effect. Plasma phospholipid (PL) and cholesteryl ester (CE) subtractions reflected the dietary fatty acids. Significant enrichment of CE n-3 fatty acids occurred in the MHO group without significant alterations in any other acyl group. Specificity of LCAT for linoleic acid predominated in both groups. An in vitro study of the molecular species of LCAT derived CE revealed higher concentrations of docosahexaenoic acid (DHA) than those detected in plasma CE, while eicosapentaenoic acid (EPA) levels were similar. This finding suggests that the cellular component of canine cholesterol metabolism, absent from the in vitro study, may contribute to the differential metabolism of EPA and DHA. This information may be important in furthering the molecular basis for such differential effects in the pathogenesis of atherosclerosis and thrombotic phenomena. Furthermore, it is concluded that changes seen in plasma lipid/lipoprotein distributions were likely due to increased total dietary fat. Elevations of plasma cholesterol was characterized by increased ot, rather than P lipoprotein fractions. Additionally, while n-3 and n-6 polyunsaturated fatty acid (PUFA) supplements did not change canine LCAT activities at the dosage used, incorporation of both fatty acid families did occur in PL substrate and CE product.
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Citation
McAlister, Kristina Gambrell (1994). Alterations in canine plasma lipoproteins and lecithin: cholesterol acyltransferase activities during fish oil supplementation. Master's thesis, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1994 -THESIS -M114.
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