Effects of dietary lipids on behaviour, lipid biosynthesis and lipid composition, in rat platelets.

Rats of either sex were fed for 18 and 34 weeks respectively diets containing 40% (by weight) lipids with polyunsaturated fatty acids representing 1.34% or 13.2% of total calories. Platelet reactivity to thrombin, platelet fatty acid composition and incorporation of [14C]acetate into platelet lipids were investigated. Diets rich in saturated fatty acids markedly increased platelet sensitivity to thrombin. The concentration of 20:3 and 22:3 of the (n - 9) series and of 20:3 and 22:5 of the (n - 6) series were increased at the expense of 18:2 and 22:4 of the (n - 6) family in platelet lipids. 20:4 (n - 6) was unchanged. The fatty acid changes were more pronounced in male rats and after 34 weeks. [14C]Acetate incorporation into total platelet lipids and particularly into choline phosphoglycerides and ceramides was lower in animals fed saturated fats. This diet reduced the synthesis of 16:0 and of 22:4(n - 6) in platelet total fatty acids, while that of 22:3(n - 9) was markedly enhanced. This study showed that long-term feeding of high-saturated-low-polyunsaturated fat diets in rats induced marked changes in platelet lipid synthesis and composition, in both sexes. The lipid synthesis modification appears to be more pronounced in males than in females. The changes in the fatty acids 20:3(n - 9), 22:3(n - 9) and 22:4(n - 6) appeared to be closely related to platelet behaviour. The balance between the content and synthesis of these last fatty acids might be of significance for the effect of diet on thrombogenesis.