[Effect of melatonin on hyperoxia-induced oxidant/antioxidant imbalance in the lung of neonatal rats with chronic lung disease].
OBJECTIVE
To study the effect of melatonin, a potent antioxidant both in vitro and in vivo, on hyperoxia-induced oxidant/antioxidant imbalance in the lung of neonatal rats with chronic lung disease (CLD).


METHODS
Ninety neonatal rats were randomly divided into three groups (n=30 each): air-exposed, hyperoxia-exposed, melatonin-treated (4 mg/kg melatonin was administered 30 minutes before hyperoxia exposure and once daily after exposure). CLD was induced by hyperoxia exposure (FiO2=0.85). Lung specimens were obtained 3, 7, and 14 days after exposure (n=10 each) for histopathologic examination. The levels of total antioxydase capacity (T-AOC), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), myeloperoxidase (MPO), catalase (CAT), nitrite/nitrate, and malondialdehyde (MDA) in the lung were assayed by the spectrophotometer.


RESULTS
The histopathologic examination showed that lung damage was obviously alleviated in the melatonin-treated group. The levels of T-AOC, GSH-Px, SOD and CAT in the lung were significantly higher in the melatonin-treated group than those in the other two groups at all time points (p<0.05). The levels of MPO, nitrite/nitrate and MDA in the lung increased significantly in the untreated hypoxia-exposed group compared with those in the air-exposed group at all time points (p<0.05 or 0.01), while the levels of MPO, nitrite/nitrate and MDA in the melatonin-treated group were significantly reduced as compared with the untreated hypoxia-exposed group (p<0.05).


CONCLUSIONS
Melatonin may reverse oxidant/antioxidant imbalance in hyperoxia-induced lung disease, thus providing a protective effect against CLD in neonatal rats.
Pan
Li
L
Department of Pediatrics, Shengjing Hospital of China Medical University, Shenyang 110004, China.
Xu
Wei
W
Fu
Jian-Hua
JH
Xue
Xin-Dong
XD
D000818:Animals; D000831:Animals, Newborn; D000975:Antioxidants / Q000494:pharmacology*; D002908:Chronic Disease; D005260:Female; D018496:Hyperoxia / Q000378:metabolism*; D008168:Lung / Q000378:metabolism*; D008171:Lung Diseases / Q000378:metabolism*; D008297:Male; D008315:Malondialdehyde / Q000032:analysis; D008550:Melatonin / Q000494:pharmacology*; D009569:Nitric Oxide / Q000032:analysis; D009195:Peroxidase / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar
D000975:Antioxidants; D009569:Nitric Oxide; D008315:Malondialdehyde; D009195:Peroxidase; D008550:Melatonin