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Keywords:

Animals, Dietary Fats, Fatty Acid Desaturases, Fatty Acids, Fatty Acids, Essential, Fatty Acids, Unsaturated, Isomerism, Male, Microsomes, Liver, Rats, Rats, Inbred Strains, 07 Agricultural and Veterinary Sciences, 09 Engineering, 11 Medical and Health Sciences, Nutrition & Dietetics, 3205 Medical biochemistry and metabolomics

Abstract:

Studies are reported on the effects of dietary trans fatty acids on the 6- and 9-acyl desaturase activities in the liver microsomes of rats fed essential fatty acid (EFA)-deficient and non-EFA-deficient diets. In experiment I, weanling male rats were fed a semisynthetic diet with either 10% safflower oil (SAF) or 10% hydrogenated coconut oil (HCO). At the age of one year, half of the dietary fat was replaced by a supplement containing elaidate, linolelaidate and cis, trans-trans,cis-18:2 (TRANS) for 12 weeks. In experiment II, male rats which were kept from weaning on a 10% (SAF + TRANS, or 5% HCO + 5% TRANS. Feeding TRANS depressed the 6-desaturase activity in the liver microsomes, especially in the EFA-deficient rats (HCO + TRANS group of experiment I). Unlike the 6-deaturase activity, the 9-desaturase activity was not inhibited by the dietary trans fatty acids and was significantly stimulated in the non-EFA-deficient rats (SAF + TRANS group of experiment I and HCO + TRANS groups of experiment II). This was evidence by incubation reaction and by comparisons of fatty acid consumptions and microsomal fatty acid levels, showing extra biosynthesis of 16:1 and 18:1 when TRANS was fed. The biosynthesis of essential (n-6) fatty acids was depressed by the TRANS supplement in EFA-deficient as well as in non-EFA-deficient animals.