Dietary virgin olive oil protects against lipid peroxidation and improves antioxidant status in the liver of rats chronically exposed to ethanol.

Excessive ethanol intake induces severe tissue damage particularly in the liver through the generation of reactive oxygen species. The aim of this study was to determine the effect of a virgin olive oil-rich diet on oxidative stress induced by chronic ethanol exposure in rats. Wistar rats were treated daily with a 35% ethanol solution for 6 weeks and fed with a standard chow or a diet containing 5% virgin olive oil. By administering ethanol to rats, a severe toxicity occurred in their liver, as assessed by the significantly elevated levels of serum transaminases. The hepatic malondialdehyde level, indicator of lipid peroxidation, was also increased in ethanol-treated rats, whereas the hepatic antioxidant enzyme activities, namely, superoxide dismutase, glutathione peroxidase, and catalase were significantly reduced. The activity of glutathione reductase remained unchanged in rats. Fatty acid composition of the liver was also significantly changed with ethanol intake. In contrast, virgin olive oil intake during ethanol treatment in rats resulted in a higher antioxidant activity and inhibited toxicity to the liver, as monitored by the reduction of transaminases levels and hepatic lipid peroxidation. Rats showed a better profile of the antioxidant system with normal glutathione peroxidase activity and ameliorated superoxide dismutase and catalase activities. In conclusion, results of this study indicate that olive oil ingestion by rats protects the liver from ethanol-induced oxidative damage by affecting the cellular redox potential.

Resveratrol, a red wine polyphenol, attenuates ethanol-induced oxidative stress in rat liver.

The involvement of oxidative stress in the pathogenesis of alcoholic diseases in the liver has been repeatedly confirmed. Resveratrol, a natural phytoalexin present in grape skin and red wine possesses a variety of biological activities including antioxidant. This study was conducted to evaluate whether resveratrol has a preventive effect on the main indicators of hepatic oxidative status as an expression of the cellular damage caused by free radicals, and on antioxidant defence mechanism during chronic ethanol treatment. Wistar rats were treated daily with 35% ethanol solution (3 g/kg/day i.p.) during 6 weeks and fed basal diet or basal diet containing 5 g/kg resveratrol. Control rats were treated with i.p. saline and fed basal diet. Experimentally, chronic ethanol administration leads to hepatotoxicity as monitored by the increase in the level of hepatic marker enzymes and the appearance of fatty change, necrosis, fibrosis and inflammation in liver sections. Ethanol also enhanced the formation of MDA in the liver indicating an increase in lipid peroxidation, a major end-point of oxidative damage, and caused drastic alterations in antioxidant defence systems. Particularly the activities of hepatic superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) were found reduced by ethanol treatment while glutathione reductase (GR) activity was unchanged. Dietary supplementation with resveratrol during ethanol treatment inhibited hepatic lipid peroxidation and ameliorated SOD, GPx and CAT activities in the liver. Conclusively, we can suggest that resveratrol could have a beneficial effect in inhibiting the oxidative damage induced by chronic ethanol administration, which was proved by the experiments that we conducted on rats.