Naringin has an antiatherogenic effect with the inhibition of intercellular adhesion molecule-1 in hypercholesterolemic rabbits

Abstract

Naringin, a bioflavonoid found in citrus fruit peel, is known to have an antioxidative effect, but its effect on atherosclerosis has not been studied. This study evaluated the effect of naringin on blood lipid levels and aortic fatty streaks, and its action mechanism in hypercholesterolemic rabbits. Male New Zealand white rabbits were fed a 0.25% cholesterol diet and divided into an untreated group (n = 4), a naringin-treated group (n = 5; 500 mg/kg per day), and a lovastatin-treated group (n = 5; 20 mg/kg per day). After 8 weeks, blood was sampled and analyzed biochemically. Aorta and liver were harvested and examined histologically. Cholesterol level in rabbits fed the 0.25% cholesterol diet reached 17 times normal and decreased in the rabbits fed naringin and lovastatin, whose effects were not statistically significant (p > 0.05). However, both naringin and lovastatin effectively decreased the area of fatty streak in thoracic aorta on macroscopic analysis (p < 0.05) and significantly reduced subintimal foam cell infiltration on microscopic morphometry (p < 0.05). These foam cells were macrophages on immunohistochemical analysis. Naringin treatment inhibited hypercholesterolemia-induced intercellular adhesion molecule-1 (ICAM-1) expression on endothelial cells. Hypercholesterolemia caused fatty liver and elevation of liver enzymes, which was prevented by naringin but not by lovastatin. Naringin significantly reduced fatty streak formation and neointimal macrophage infiltration and also inhibited the expression of ICAM-1 in endothelial cells, suggesting that suppression of ICAM-1 contributed to the antiatherogenic effect. Naringin, unlike lovastatin, has a hepatoprotective action.