Effects of N-acetylcysteine and Methylprednisolone on Lung Injury in a Paraquat-Poisoned Rat Model

ABSTRACT

BACKGROUND: This study evaluated the inhibitory effects of N-acetylcysteine(NAC) and methylprednisolone on lung injury in the paraquat-poisoned rat model. METHODS: Sixty rats were divided into four groups(n=15 in each group) accordingly to the drug administered group I, only intraperitoneally injected paraquat (20 mg/kg); group II, intraperitoneally injected paraquat and NAC(300 mg/kg); group III, intraperitoneally injected paraquat and methylprednisolone(60 mg/kg); and group IV, intraperitoneally injected paraquat, NAC(300 mg/kg), and methylprednisolone(60 mg/kg). On the 7th day after injection, the survival rate of experimental rats and the positive area of collagen fiber in the injured lung stained by Masson's trichrome were evaluated. RESULTS: 1. There were no differences in the 7-day survival rates for the four groups. 2. The percent of collagen fiber for group II(6.3+/-4.7%) was significantly decreased in comparison with that for group I (14.4+/-9.7%). 3. The percent of collagen fiber for Group III(13.2+/-5.9%) was not significantly different from that for group I(14.4+/-9.7%). 4. The percent of collagen fiber for Group IV(6.9+/-4.6%) was significantly decreased in comparison with that for group I, but was not different from that for group II. CONCLUSION: These results suggest that NAC protects against pulmonary fibrosis in paraquat-poisoned rats whereas methylprednisolone does not protect against pulmonary fibrosis.