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Protective effects of melatonin therapy in model for neonatal hyperoxic lung injury.

CONTEXT
Bronchopulmonary dysplasia (BPD) is a common outcome of premature birth. Currently, no effective preventive therapy is available for BPD, but the major role of O2 toxicity in the development of BPD has gained attention, particularly for developing new antioxidants for prevention. The major protective mechanism of melatonin (MT) includes free-radical scavenging activity and activation of the cyclooxygenase-prostoglandin enzyme system.


OBJECTIVE
The aim of this study was to evaluate the effects of MT on cytoprotection and healing in a model of hyperoxic lung injury in newborn rats.


METHODS
This is a case-control study design.


SETTING
The study occurred at the Gulhane Military Medical Academy in Ankara, Turkey.


INTERVENTION
A total of 60 newborn pups from dated, Sprague-Dawley, pregnant rats were divided equally into 3 groups as follows: (1) control group, (2) hyperoxia-exposed group, and (3) hyperoxia-exposed plus MT-treated group (MT group). Hyperoxia was performed by placing these pups in an oxygen chamber for 14 d during which oxygen was continuously delivered.


OUTCOME MEASURES
At the end of the 14 d, lung specimens were collected and evaluation of the lamellar-body count and determination of histopathological scores were performed. Also, the activities of superoxide dysmutase (SOD), glutathione peroxidase (GSH-Px), and malondialdehyde (MDA) were assessed.


RESULTS
The histopathological scores of the MT group were significantly lower than those of the hyperoxia-exposed group. The mean lamellar-protein and radial-alveolar counts in the MT group were found to be significantly higher than those of the hyperoxia-exposed group. Also, SOD and GSH-Px levels were significantly higher and MDA levels were significantly lower in the MT group compared with the hyperoxia-exposed group.


CONCLUSION
MT therapy was found to have a protective effect in a model for hyperoxic lung injury in neonatal rats. Therefore, the research team suggests that MT therapy may be used for prevention of BPD in preterm infants after confirmation of this data by future clinical studies.