Effect of melatonin on the expression of nuclear factor-kappa B and iNOS in lung tissue of acute paraquat poisoned rats

[Objective] This study aimed at investigating the effect of MT on NF-κB activity and the expression of inducible nitric oxide synthase (iNOS) in lung tissue of acute paraquat poisoned rats. [Methods] 45 Sprague-Dawley (SD) rats weighing 180 g to 200 g were randomly divided into three experimental groups: Poisoned group, MT group and Control group. At 3 days after exposure, lung pathological changes of rats were observed, NF-κB activity in the lung tissues was assessed by electrophoresis mobility shift assay (EMSA), and expression of iNOS mRNA were evaluated by RT-PCR. At the same time, levels of nitric oxide (NO) and malondialdehyde (MDA) in serum were detected. [Results] Compared with that in control group, NF-κB activity and expression of iNOS mRNA in lung tissue of Poisoned group markedly increased, levels of nitric oxide (NO) and malondialdehyde (MDA) in serum raised significantly in Poisoned group (P 0.01 respectively); There was a significant decrease in NF-κB activity and expression of iNOS mRNA in the lung tissues in MT group comparing with Poisoned group (P 0.01 respectively); and the levels of NO and MDA in serum decreased significantly (P 0.01) in MT group. [Conclusions] Nuclear NF-κB could play an important role in lung injury of poisoned rats. MT may inhibit the expression of NF-κB and therefore might have a therapeutical effect in acute paraquat poisoning.