Effects of varying dietary fatty acid ratios on plasma lipids and platelet function in the African green monkey

Abstract

The influence of varying dietary fatty acid ratios on plasma lipids, platelet function and the potential for thrombosis was evaluated in the African green monkey ( Cercopithecus aethiops), an animal model widely used in cardiovascular research. Ten adult animals, 5 males and 5 females, at intervals of 2 months, were fed a series of 7 diets with fatty acid ratios (P:S) ranging from 3:1 to 1:4. Platelet aggregation in vitro, plasma levels of β-thromboglobulin and platelet factor 4, platelet membrane fatty acid composition and plasma lipids including total cholesterol, HDL and LDL were monitored at the end of each dietary period. Platelet hypersensitivity to ADP aggregation (3 and 10 μM) and plasma β-thromboglobulin were elevated in both males and females when dietary P:S exceeded 1.5:1 (β-TG = 45 ng/ml) as compared to control diets either reflecting current North American or that recommended as a desirable dietary goal (P: S = 1 : 1, β-TG = 10 ng/ml). Diets enriched in saturated fatty acids (P:S = 1:2) also altered platelet function, but the effects were most consistently observed in female animals (β-TG = 32 ng/ml). Platelet hypersensitivity was lost and (β-TG levels were at baseline when the animals were returned to the control diets. Platelet sensitivity did not correlate with membrane composition which generally reflected dietary composition. Both the saturated and the polyunsaturated fatty acid enriched diets lowered plasma HDL levels, and the saturated fatty acid diets elevated plasma LDL. In general, a positive relationship was observed between plasma LDL and β-TG; however, this was statistically significant ( P < 0.05) only with polyunsaturated fatty acid diets in female animals. Changes in either LDL or HDL were not consistently related to platelet function, suggesting independence of the platelet effects from plasma lipoproteins.