title: Effect of dietary n-3 and n-6 fatty acids on fatty acid desaturation in rat liver.
abstract: To study the effect of high-fat diets with varying contents of n-3 and n-6 fatty acids on the metabolism of essential fatty acids, the rat liver microsomal fatty acid desaturases were measured. The rats were fed for 3 weeks with diets high in linseed oil (18:3(n-3)), sunflower seed oil (18:2(n-6)) or fish oil (20:5(n-3) and 22:6(n-3)) (20%, w/w) using pellet fed rats as a reference. The delta 6-desaturase using 18:2(n-6) or 18:3(n-3) as substrates was stimulated 1.5-2.5-fold by linseed or sunflower seed oil, compared to the pellet reference. The delta 5-desaturase was stimulated 3.5-fold with linseed oil and 2.5-fold with sunflower seed oil, while the delta 9-desaturase was inhibited by all the high-fat diets. The delta 6-, 5- and 9-desaturase activities were in all cases considerably reduced with fish oil as compared to linseed and sunflower seed oil diets. With pellet fed rats the rates were highest for delta 9-desaturation and in decreasing order lower for delta 5-desaturation, delta 6-desaturation with 18:3 (n-3) as substrate and finally delta 6-Desaturation with 18:2(n-6) as substrate. The content of 20:4(n-6) in liver phospholipids increased with the diets rich in 18:2(n-6), and was reduced for the fish oil diet enriched in 20:5 and 22:6(n-3) fatty acids. The amount of 20:5(n-3) in phospholipids was as high with linseed oil diet as with the fish oil diet, while the 22:6(n-3) content was only increased with the fish oil diet.
authors.affiliation: Institute for Nutrition Research, University of Oslo, Norway.
authors.forename: E N
authors.initials: EN
authors.lastname: Christiansen
authors.forename: J S
authors.initials: JS
authors.lastname: Lund
authors.forename: T
authors.initials: T
authors.lastname: Rørtveit
authors.forename: A C
authors.initials: AC
authors.lastname: Rustan
mesh_terms: D000818:Animals; D004042:Dietary Fats, Unsaturated / Q000008:administration & dosage / Q000494:pharmacology*; D044943:Fatty Acid Desaturases / Q000378:metabolism*; D005227:Fatty Acids / Q000378:metabolism; D005395:Fish Oils / Q000008:administration & dosage / Q000494:pharmacology; D008042:Linolenic Acids / Q000378:metabolism; D008043:Linseed Oil / Q000008:administration & dosage / Q000494:pharmacology; D008099:Liver / Q000378:metabolism; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology*; D010743:Phospholipids / Q000378:metabolism; D010938:Plant Oils / Q000008:administration & dosage / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D000074242:Sunflower Oil
chemical_list: D004042:Dietary Fats, Unsaturated; D005227:Fatty Acids; D005395:Fish Oils; D008042:Linolenic Acids; D010743:Phospholipids; D010938:Plant Oils; D000074242:Sunflower Oil; D008043:Linseed Oil; D044943:Fatty Acid Desaturases