Ezetimibe impairs uptake of dietary cholesterol oxidation products and reduces alterations in hepatic cholesterol metabolism and antioxidant function in rats.

Dietary cholesterol oxidation products (COP) induce various adverse effects, including development of atherosclerosis, modulation of lipid metabolism, and unfavorable changes in the antioxidant system. Therefore, we examined the effects of ezetimibe, a cholesterol absorption inhibitor on hepatic cholesterol metabolism and down-regulation of the antioxidant system in rats fed COP. Rats were fed a purified diet containing 0.3 % COP with or without ezetimibe (0.07 mg/100 g body weight) for 27 days. Levels of COP in both the plasma and liver were lowered by ezetimibe through promotion of COP excretion into the feces. Reflecting this effect, an increase in the arteriosclerotic index and a reduction in the mRNA expression of hepatic cholesterol biosynthesis transcripts by dietary COP were observed. Moreover, the ferric reducing ability of the plasma also was significantly higher in rats fed COP plus ezetimibe than in those fed COP alone. Finally, we also observed that ezetimibe enhanced the down-regulation of hepatic fatty acid synthesis in rats fed COP. Thus, ezetimibe, which inhibits the absorption of dietary COP from the small intestine, may exert preventive effects on dietary COP-induced disruption of cholesterol and fatty acid metabolism in the liver and down-regulation of the antioxidant system.