Melatonin attenuates lung injury in a hind limb ischemiaâreperfusion rat model

Objective: This study evaluated the protective antioxidant effect of melatonin on lung injury as a remote organ after skeletal muscle ischemiaâreperfusion in rats. Methods: Thirty male Wistar rats were allocated randomly into three experimental groups: operated with no ischemia (Sham) group, ischemiaâreperfusion group and ischemiaâreperfusion + melatonin group. Hind limb ischemia was induced by clamping the femoral artery. After 2 h ischemia, the clamp was removed and the animal underwent 24 h reperfusion. Rats in the ischemiaâreperfusion + melatonin group received melatonin (10 mg/kg i.v.), immediately before the clamp was removed. At the end of the trial, animals were euthanized and the lungs were removed for water content determination, histopathological and biochemical studies. Results: In the ischemiaâreperfusion + melatonin group, tissues showed less intense histological abnormalities such as neutrophilic infiltration, intra-alveolar hemorrhage and edema compared with the ischemiaâreperfusion group. Histopathologically, there was a significant difference (P < 0.05) between the two groups. The lung water content in the ischemiaâreperfusion + melatonin group was significantly lower than the ischemiaâreperfusion group (P < 0.05). Lung tissue myeloperoxidase (MPO) activity and nitric oxide (NO) level were significantly (PÂ