Protective effects of tea polyphenols on liver injury induced by intestinal ischemia reperfusion in rats

Objective To investigate the protective effects of tea polyphenols (TP) on intestinal ischemia reperfusion (I/R) induced injury of liver in rats and possible action mechanism, so as to provide preclinical pharmacological basis for its new clinical uses. Methods Rats were randomly divided into six groups: Sham group, model group, and TP (100.0, 50.0, 25.0, and 12.5 mg/kg) groups. Intestinal I/R model was established by clamping superior mesenteric artery for 60 min and reperfusing for 120 min. TP was administered by sublingual vein at 20 min before ischemia. In Sham group, superior mesenteric artery was only isolated without clamping. Blood samples and liver tissue samples were collected after reperfusion lasting 120 min. SOD activity, MDA and NO levels in serum and liver tissue were determined. Histomorphology changes of liver tissue were observed with light microscope. Results Compared with Sham group, after intestinal I/R injury, activity of SOD was decreased, while the levels of MDA and NO was increased in serum and liver tissue. At the same time, histomorphology of liver was destroyed obviously, as seen by light microscope. In comparison with model group, TP could dose-dependently increase SOD activity, decrease MDA and NO levels in serum and liver tissue. Also, TP could dose-dependently attenuate liver tissue injury, as evidenced by microscopic examination of histomorphology. Conclusion TP can dose-dependently protect liver significantly and attenuate intestinal I/R injury. These protective effects are related to their anti-free-radical actions with diminishing the aggregation and activation of polymorphonuclear neutrophils (PMN) and inhibiting the release of NO.