The effects of fish oil on lipid and lipoprotein metabolism in F1B and golden Syrian hamsters

We previously determined that fish oil induced hyperlipidemia in F₁B hamsters. In this study, we investigated the influence of fish oil enriched diets on lipid and lipoprotein metabolism in F₁B and GS hamsters to determine if the response was preserved within animal strain. Hamsters were fed either fish oil, a diet high in monounsaturated fatty acids, or a diet with an n-6:n-3 fatty acid ratio of 5. Fish oil induced hyperlipidemia to a much greater extent in F₁B compared to GS hamsters. Fish oil fed F₁B hamsters had milky plasma containing chylomicron-like particles which was not observed in GS hamsters. The concentration of plasma cholesterol, triglycerides, free cholesterol, and cholesterol esters were significantly higher in fish oil fed F₁B hamsters compared to GS hamsters. Feeding a diet with an n-6:n-3 ratio of 5 markedly decreased all lipid parameters in F₁B and GS hamsters compared to the fish oil diet. However, this diet increased LDL-cholesterol concentrations compared to the diet rich in monounsaturated fatty acids, suggesting that even a small amount of fish oil in the diet has a deleterious effect on the plasma lipoprotein profile. The presence of milky plasma, and elevated triglyceride concentrations suggested an inhibition of clearance of triglyceride-rich lipoproteins in F₁B hamsters. Thus, we investigated the activity of LPL, MTTP, LDL-receptor mRNA expression, and the protein expression of apoB and apoE to determine if diet or animal strain had an effect on these aspects of lipoprotein clearance. LPL activity, MTTP activity, and LDL-receptor mRNA expression were unaffected by diet, however LPL activity was lower in F₁B hamsters. In addition, the protein expression of apoB and apoE were altered by both diet and animal strain. In conclusion, comparison of F₁B and GS hamsters allowed us to attribute the fish oil induced hyperlipidemia to diversity in animal strain