Effects of cholesterol supplementation on antioxidant enzyme activities in rat hepatic tissues: possible implications of hepatic paraoxonase in atherogenesis.
OBJECTIVE
The effects of cholesterol supplementation on antioxidant enzyme activities were investigated 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 paraoxinase-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.
Durak
I
I
Ankara University Medical Faculty, Department of Biochemistry, Ankara, Turkey. ilker_durak@yahoo.com
Ozbek
H
H
Devrim
E
E
Karagenç
N
N
Ergüder
I B
IB
D000818:Animals; D001161:Arteriosclerosis / Q000188:drug therapy / Q000378:metabolism; D043303:Aryldialkylphosphatase / Q000096:biosynthesis / Q000187:drug effects / Q000378:metabolism*; D002374:Catalase / Q000378:metabolism; D002784:Cholesterol / Q000097:blood; D002791:Cholesterol, Dietary / Q000008:administration & dosage*; D008076:Cholesterol, HDL / Q000097:blood; D019587:Dietary Supplements; D005979:Glutathione Peroxidase / Q000378:metabolism; D008099:Liver / Q000201:enzymology*; D008297:Male; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013482:Superoxide Dismutase / Q000378:metabolism
D002791:Cholesterol, Dietary; D008076:Cholesterol, HDL; D002784:Cholesterol; D002374:Catalase; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D043303:Aryldialkylphosphatase