Melatonin attenuates lung injury in a hind limb ischemia-reperfusion rat model

Objective: this study evaluated the protective antioxidant effect of melatonin on lung injury as a remote organ after skeletal muscle ischemia-reperfusion in rats. methods: thirty male wistar rats were allocated randomly into three experimental groups: operated with no ischemia (sham) group,ischemia-reperfusion group and ischemia-reperfusion + 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 ischemia-reperfusion + 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 ischemia-reperfusion + melatonin group,tissues showed less intense histological abnormalities such as neutrophilic infiltration,intra-alveolar hemorrhage and edema compared with the ischemia-reperfusion group. histopathologically,there was a significant difference (p < 0.05) between the two groups. the lung water content in the ischemia-reperfusion + melatonin group was significantly lower than the ischemia-reperfusion group (p < 0.05). lung tissue myeloperoxidase (mpo) activity and nitric oxide (no) level were significantly (p < 0.05) increased by ischemia-reperfusion. the increase in these parameters was reduced by melatonin. comparing the ischemia-reperfusion + melatonin group with the sham group,no significant increase in all analyzed aspects of the research was observed. © 2013 sociedade portuguesa de pneumologia.