Lipid peroxidation and antioxidant defense systems in rat liver after chronic ethanol feeding.
The effects of chronic ethanol feeding on hepatic lipid peroxidation, ascorbic acid, glutathione and vitamin E levels were investigated in rats fed low or adequate amounts of dietary vitamin E. Hepatic lipid peroxidation was significantly increased after chronic ethanol feeding in rats receiving a low-vitamin E diet, indicating that dietary vitamin E is an important determinant of hepatic lipid peroxidation induced by chronic ethanol feeding. No significant change was observed in hepatic non-heme iron content, but hepatic content of ascorbic acid and glutathione was increased by ethanol feeding. Both low dietary vitamin E and ethanol feeding significantly reduced hepatic alpha-tocopherol content, and the lowest hepatic alpha-tocopherol was found in rats receiving a combination of low vitamin E and ethanol. Plasma alpha-tocopherol was elevated after ethanol feeding, probably because of the associated hyperlipemia. Both the ratio of plasma alpha-tocopherol/plasma lipid and the red blood cell alpha-tocopherol were reduced by ethanol feeding. Furthermore, ethanol feeding caused a marked increase of hepatic alpha-tocopheryl quinone, a metabolite of alpha-tocopherol by free radical reactions. Ethanol feeding caused little changes of alpha-tocopherol and alpha-tocopheryl quinone content in mitochondria, whereas a striking increase in alpha-tocopheryl quinone was observed in microsomes. These data suggest that ethanol feeding causes a marked alteration of vitamin E metabolism in the liver and that the combination of ethanol with a low-vitamin E intake results in a decrease of hepatic alpha-tocopherol content which renders the liver more susceptible to free radical attack.
Kawase
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Section of Liver Disease and Nutrition, Bronx Veterans Administration Medical Center, New York 10468.
Kato
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Lieber
C S
CS
D000818:Animals; D000975:Antioxidants / Q000378:metabolism*; D001205:Ascorbic Acid / Q000378:metabolism; D004334:Drug Administration Schedule; D000431:Ethanol / Q000008:administration & dosage*; D005609:Free Radicals; D005978:Glutathione / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects* / Q000502:physiology; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008862:Microsomes, Liver / Q000378:metabolism; D008930:Mitochondria, Liver / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D014810:Vitamin E / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000378:metabolism
D000975:Antioxidants; D005609:Free Radicals; D014810:Vitamin E; D000431:Ethanol; C002421:tocopherylquinone; D005978:Glutathione; D001205:Ascorbic Acid