Protective Effects Of Melatonin On Acute Lung Injury Induced By Smoke Inhalation Injury In Rats

Objective To investigate the protective effects of melatonin on acute lung injury induced by smoke inhalation injury in rats.Method Seventy-two rats were randomly divided into control group、injury group and melatonin group. The control group were received no treatment. The injury group were administered i.p. the same volume solvent of melatonin. The melatonin group were administered i.p. melatonin (10ml/kg, q8h) immediately after inhalation injury. Abdominal aortic blood of all rats was collected at3h,12h,24h three-phase. Then they were all decapitated and lung tissues were collected. Serums were prepared for tumor necrosis factor a(TNF-a), interleukin6(IL-6)and interleukin10(IL-10).Lung homogenates were examined for superoxidedismutase (SOD),malondialdehyde (MDA) and myeloperoxidase (MPO). The pathological changes in lungs were also examined under an optical microscope.Results Under the microscope, compared with control group, lungs of injury group and melatonin group were observed to have infiltrating inflammatory granulocytes, diffused alveolar septum thickening. The pathological change of lung in melatonin group was minimal in comparison to injury group. Compared with control group, levels of TNF-a and IL-6were higher in melatonin group and injury group visibly. The TNF-a and IL-6levels of melatonin group were lower than those of the injury group visibly. The IL-10levels of injury group had no difference with that of control group, the IL-10level of melatonin group was higher than that of control group and injury group visibly.Compared with control group,levels of MDA and MPO were higher in melatonin group and injury group visibly, the MDA and M PO levels of melatonin group were lower than injury group visibly.Compared with control group, the SOD levels were lower in melatonin group and injury group visibly.The SOD levels of melatonin group were higher than injury group visibly.Conclusion Melatonin can influence inflammatory response and oxidative stress, and have some protective effects on acute lung injury induced by smoke inhalation injury probably.