Protective effects of green tea against hepatic injury induced by high-cholesterol diet in rats: histopathological analysis, oxidative DNA damage and COX-2 expression.

Purpose: The goal of this study was to investigate whether daily administration of green tea is able to protect the liver injury induced by cholesterol.

Methods: Male Wistar rats (n = 24) were distributed into four groups: group 1, negative control; group 2, cholesterol at 1% (w/w) in the diet treated for 5 weeks; group 3, cholesterol at 1% treated for 5 weeks and green tea at 1% (w/v) in drinking water in the last week only and group 4, cholesterol and green tea at 1% in drinking water for 5 weeks.

Results: The results pointed out that treatment with green tea in the last week (group 3) showed mild degenerative changes of liver tissue in cholesterol exposed group when compared to group 2. Green tea aqueous extract was not able to reduce cholesterol levels, that is, no significant statistical differences (p > 0.05) were noticed when compared to positive control group. Nevertheless, green tea was able to decrease oxidative deoxyribonucleic acid (DNA) damage either to peripheral blood or to liver cells as depicted by significant statistical differences (p < 0.05) in the mean tail moment between groups treated with green tea and cholesterol and cholesterol only. Furthermore, histomorphometric analysis of COX-2 expression revealed that in groups exposed to green tea they were significantly decreased (p < 0.05), regardless of time exposure adopted.

Conclusion: Taken together, our results suggest that daily administration of green tea for at least 7 days displays some preventive properties as indicated by COX-2 downregulation and decreased oxidative DNA damage.