Effect of dietary fats on desaturase activities and the biosynthesis of fatty acids in rat-liver microsomes.
Four groups of rats were fed diets containing 15% (w/w) high-oleic safflower oil (SFO, rich in cis-18:1 acids), a mixture of 80% partially hydrogenated soybean oil plus 20% corn oil (H + CO, rich in trans-18:1 acids), lard (L, rich in saturated fatty acids) and corn oil (Co, rich in 18:2 omega 6). Fatty acid composition of liver microsomes and activities of the delta 5, delta 6 and delta 9 desaturases were determined. Microsomal delta 6 desaturase activity and arachidonic acid were lower in the H + CO group compared with SFO of L. No difference was found in the delta 5 or delta 6 desaturase activity of CO and SFO groups. Thus, the oleic-acid level of the SFO diet had no effect on the metabolism of 18:2 omega 6. Fluorescent polarization studies, using trans-parinaric acid as a probe, showed no differences between the physical states of phospholipid vesicles made from lipids isolated from each group. We concluded that the trans-18:1 acids in partially hydrogenated soybean oil have a more inhibitory effect than saturated acids on EFA metabolism, even in the presence of adequate amounts of essential fatty acid.
D000818:Animals; D004041:Dietary Fats / Q000494:pharmacology*; D044943:Fatty Acid Desaturases / Q000378:metabolism*; D005227:Fatty Acids / Q000032:analysis / Q000096:biosynthesis*; D008297:Male; D008862:Microsomes, Liver / Q000187:drug effects / Q000378:metabolism*; D009821:Oils / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains
D004041:Dietary Fats; D005227:Fatty Acids; D009821:Oils; D044943:Fatty Acid Desaturases