Durak, IÖzbek, HDevrim, EKaragenç, NErgüder, IB2025-05-102025-05-1020040939-47531590-372910.1016/S0939-4753(04)80007-32-s2.0-7744237562https://doi.org/10.1016/S0939-4753(04)80007-3https://hdl.handle.net/20.500.14720/14630Devrim, Erdinc/0000-0001-7326-5104; Erguder, Berrin Imge/0000-0002-7945-3074Background and Aim: The effects of cholesterol supplementation on antioxidant enzyme activities were investigated in hepatic tissue taken from Sprague Dawley rats. Methods and Reults: The study involved 14 male Sprague Dawley rats: seven fed a normal laboratory diet and seven a normal diet plus cholesterol (3.6 g/kg/day) for three months, during which blood samples were obtained to measure serum cholesterol levels. At the end of the 3-month period, the livers were surgically removed in order to measure antioxidant enzyme activities (superoxide dismutase, catalase, glutathione peroxidase and paraoxonase-1). At the end of the study period, serum total cholesterol and HDL-cholesterol levels were significantly higher in the cholesterol-fed group than the control group. There were no significant between-group differences in hepatic superoxide dismutase, catalase and glutathione peroxidase activities, but there was a significant decrease in hepatic paraoxonase-1 activity in the cholesterol-fed group. Conclusions: Cholesterol supplementation significantly decreases paraoxonase-1 activity in rat liver tissue without changing the activities of other antioxidant enzymes. These results suggest that cholesterol significantly suppresses hepatic paraoxonase-1 synthesis. It seems that the decreased paraoxonase-1 activity in the plasma HDL-fraction of atherosclerotic patients is associated with suppressed liver synthesis. A reduction in paraoxonase-1 activity may therefore lead to the more intensive exposure of LDL to oxidant attacks. Nutr Metab Cardiovasc Dis ((C)) 2004, Medikal.eninfo:eu-repo/semantics/closedAccessAtherosclerosisCholesterolParaoxonaseAntioxidant EnzymesArticle144Q2Q221121415553599WOS:000224770300007