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.

OBJECTIVE

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 B2 (TXB2) and 6-ketoprostaglandin F(1alpha) (6-ketoPGF(1alpha)) 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 TXB2 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(1alpha) (stable metabolite of prostacyclin-PGI2; p < 0.05 for all) but increased TBARS levels and TXB2/6-ketoPGF(1alpha) ratios. Light microscopic findings were in accordance with these biochemical alterations.

CONCLUSIONS

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 PGI2 synthesis and consequently to an increase in the TXB2/6-ketoPGF(1alpha) ratio. Olive oil administration did not induce oxidant stress and it had no affect on PGI2 and TXB2 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.