title: Effects of dietary long-chain fatty acids on the rat biosynthesis of unsaturated fatty acids in the rat.
abstract: Menhaden oil (ME) was included in semisynthetic diets to study the effect of long-chain fatty acids, mainly 20:5n3 and 22:6n3, on the biosynthesis of polyunsaturated fatty acids and on the 6- and 9-desaturase activities in liver microsomes. Five experimental diets, with the following fat supplements, were fed to male rats from weaning for a period of 33 weeks: 5% safflower oil (SAF) + 10% hydrogenated coconut oil (HCO), 5% SAF + 5% HCO + 5% ME, 5% SAF + 10% ME, 15% HCO and 5% HCO + 10% ME. The last two diets were deficient in linoleic acid. The three nondeficient diets contained similar amounts of linoleic acid. Including ME in the diets depressed the 6- and 9-desaturase activities, especially in the linoleic acid--deficient rats. The synthesis of 20:4n6, 22:4n6 and 22:5n6 were depressed. These effects were related to the preferential accumulation of dietary 20:5n3 and 22:6n3 in the liver microsomes, as compared to the n6 fatty acids. It is hypothesized that dietary 20:5n3 and 22:6n3 increase the minimum requirement for linoleic acid in the diet.
mesh_terms: D000818:Animals; D004041:Dietary Fats / Q000494:pharmacology*; D004281:Docosahexaenoic Acids; D015118:Eicosapentaenoic Acid; D044943:Fatty Acid Desaturases / Q000378:metabolism*; D005227:Fatty Acids / Q000494:pharmacology*; D005231:Fatty Acids, Unsaturated / Q000096:biosynthesis* / Q000494:pharmacology; D019787:Linoleic Acid; D008041:Linoleic Acids / Q000378:metabolism; D008297:Male; D008862:Microsomes, Liver / Q000378:metabolism*; D009821:Oils / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013329:Structure-Activity Relationship
chemical_list: D004041:Dietary Fats; D005227:Fatty Acids; D005231:Fatty Acids, Unsaturated; D008041:Linoleic Acids; D009821:Oils; D004281:Docosahexaenoic Acids; D019787:Linoleic Acid; D015118:Eicosapentaenoic Acid; D044943:Fatty Acid Desaturases