RESUMO
AIM:To assess the protective role of melatonin(MEL)in a rat model of oleic-induced acute lung injury.METHODS:Twenty-four rats were randomly allocated to three groups as follows:saline(NS)injection group,oleic acid(OA)injection group and MEL plus OA injection group,the lavage protein,lung wet-to-dry weight ratio,malondialdehyde(MDA)content,superoxide dismutase(SOD)activity and lung histopathology were examined.RESULTS:(1)Injection 0.15 mL/kg of OA led to a severe acute lung injury(ALI),characterized by significantly increasing in lavage protein,lung coefficient(P＜0.01),and by histopathological alterations which presented hemorrhage,edema.thickened alveolar septum and the existence of inflammatory cells in alveolar spaces;(2)Infusion of MEL(20 mg/kg,intraperitoneally for 60 min before the oleic acid)markedly alleviated above-mentioned symptom induced by OA,consistent with decrease of MDA level(P＜0.01) and the increase of SOD activty(P＜0.01).CONCLUSION:Pre-treatment with MEL can attenuate the OA -induced ALI in rats via cleaning and preventing the formation of free radicals and further lessening the increase of alveolocapillary membrane permeability,these data suggest that MEL may be effective in the prevention of ALI.