Comparison of the Effects of Dietary Saturated, Mono-, and n–6 Polyunsaturated Fatty Acids on Blood Lipid Profile, Oxidant Stress, Prostanoid Synthesis and Aortic Histology in Rabbits

Background/Aims: To compare the effects of saturated, monounsaturated and polyunsaturated n–6 fatty acid-enriched diets on the development of atherosclerosis and thrombosis in New Zealand white male rabbits, 3- to 6-month-old animals were supplemented daily (10 g/100 g diet) with butter (n = 8), olive oil (n = 8) or corn oil (n = 8) by oral administration for 7 weeks. Methods: Total cholesterol (TC), HDL- (HDL-C) and LDL-cholesterol (LDL-C), triglycerides (TG), apolipoprotein A-1 (ApoA-1), apolipoprotein B (ApoB), lipid peroxides as thiobarbituric acid-reactive substances (TBARS), thromboxane B 2 (TXB 2 ) and 6-ketoprostaglandin F 1α (6-ketoPGF 1α ) concentrations were determined in blood samples drawn before and after each group was fed the different dietary regimens. Histological examination was performed on the aortic tissues. Results: After 7 weeks, TC, ApoB and TXB 2 increased significantly (p < 0.05) in the butter-fed animals compared to pre-experimental concentrations. Olive oil administration lead to a significant (p < 0.05) decrease in TC and ApoB levels. The corn oil-enriched diet decreased TC, LDL-C concentrations, TC/HDL-C ratios and 6-ketoPGF 1α (stable metabolite of prostacyclin-PGI 2; p < 0.05 for all) but increased TBARS levels and TXB 2 /6-ketoPGF 1α ratios. Light microscopic findings were in accordance with these biochemical alterations. Conclusion: Although effective in lipid lowering, corn oil increased oxidant stress as evidenced by increased TBARS and induced endothelial damage which lead to a reduction in PGI 2 synthesis and consequently to an increase in the TXB 2 /6-ketoPGF 1α ratio. Olive oil administration did not induce oxidant stress and it had no affect on PGI 2 and TXB 2 levels which are implicated in platelet aggregation. These findings suggest that oleic acid is more effective than linoleic acid in the protection of endothelial integrity.