Quercetin attenuates the ischemia reperfusion induced COX-2 and MPO expression in the small intestine mucosa.

Quercetin, the active substance of tea, fruits and vegetables, exerts a broad spectrum of pharmacological activities and is considered to have potential therapeutic application. The present study was designed to investigate the beneficial effect of quercetin against experimental ischemia- reperfusion (IR) injury of the small intestine in rats. Quercetin was administrated intraperitoneally 30min before 1h ischemia of superior mesenteric artery with following reperfusion periods lasting 1, 4 and 24h. The male specific pathogen-free Charles River Wistar rats were used (n=45). In acute phase, 4h after start of reperfusion, the quercetin induced a significant decrease in mucosal injury index (p<0.05) accompanied by a significant decrease in cyclooxygenase-2 (COX-2) expression in the epithelial lining of the intestinal villi in comparison with the control group (p<0.01). In the epithelium of the intestinal glands, COX-2 expression resulting from IR injury significantly increased regardless quercetin application (in control group p<0.001; in quercetin group p<0.05), but in quercetin group, significant decrease in it during 24h of reperfusion in a late phase of IR injury was detected (p<0.001). Based on morphology of COX-2 positive cells, the COX-2 positivity was found particularly in goblet cells of the intestinal villi epithelium and enteroendocrine cells respectively, in the glandular epithelium. We concluded that quercetin application attenuated mucosal damage from IR injury by inhibiting neutrophil infiltration which was demonstrated by a lower number of myeloperoxidase positive cells in the lamina propria during both phases of IR injury and the significant decrease in that in a late phase after 24h of reperfusion (p<0.05).