Erythropoietin protects the intestine against ischemia/reperfusion injury in rats

Previous studies have shown that erythropoietin (EPO) has protective effects against ischemia/reperfusion (I/R) injury in several tissues. The aim of this study was to determine whether EPO could prevent intestinal tissue injury induced by I/R, Wistar rats were subjected to intestinal ischemia (30 min) and reperfusion (60 min). A single dose of EPO (5000 U/kg) was administered introperitoneally at two different time points: either at five minutes before the onset of ischemia or at the onset of reperfusion. At the end of the reperfusion period, jejunum was removed for examinations. Myeloperoxidase (MPO), malondialdehyde (MDA), and antioxidant defense system were assessed by biochemical analyses. Histological evaluation was performed according to the Chiu scoring method. Endothelial nitric oxide synthase (eNOS) was demonstrated by immunohistochemistry. Apoptotic cells were determined by TUNEL staining. Compared with the sham, I/R caused intestinal tissue injury (Chiu score, 3 +/- 0.36 vs 0.4 +/- 0.24, P < 0.01) and was accompanied by increases in MDA levels (0.747 +/- 0.076 vs 0.492 +/- 0.033, P < 0.05), MPO activity (10.51 +/- 1,87 vs 4.3 +/- 0.45, P < 0.05), intensity of eNOS immunolabelling (3 +/- 0.4 vs 1.3 +/- 0,33, P < 0.05), the number of TUNEL-positive cells (20.4 +/- 2.6 vs 4.6 +/- 1.2, P < 0.001), and a decrease in catalase activity (16.83 +/- 2.6 vs 43.15 +/- 4.7, P < 0.0 1). Compared with the vehicle-treated I/R, EPO improved tissue injury; decreased the intensity of eNOS immunolabelling (1.6 +/- 0.24 vs 3 +/- 0.4, P < 0.05), the number of TUNEL-positive cells (9.2 +/- 2.7 vs 20.4 +/- 2.6, P < 0.0 1), and the high histological scores (1 +/- 0.51 vs 3 +/- 0.36, P < 0.01), and increased catalase activity (42.85 +/- 6 vs 16.83 +/- 2,6, P < 0,01) when given before ischemia, while it was found to have decreased the levels of MDA (0.483 +/- 0.025 vs 0.747 +/- 0.076, P < 0.05) and MPO activity (3.86 +/- 0.76 vs 10.51 +/- 1.87, P < 0.05), intensity of eNOS immunolabelling (1.4 +/- 0,24 vs 3 +/- 0.4, P < 0.01), the number of TUNEL-positive cells (9.1 +/- 3 vs 20.4 +/- 2.6, P < 0.01), and the number of high histological scores (1. 16 +/- 0.4 vs 3 +/- 0.36, P < 0.05) when given at the onset of reperfusion. These results demonstrate that EPO protects against intestinal I/R injury in rats by reducing oxidative stress and apoptosis. We attributed this beneficial effect to the antioxidative properties of EPO.