Effects of methylprednisolone on lung pathological changes in rats with paraquat intoxication

Objective:To study the effects and mechanism of methylprednisolone on lung pathological changes in rats with paraquat intoxication.Methods:Sixty Wistar rats were randomly divided into 4 groups:control group(Group A),intoxication group(Group B),15 mg/kg Methylprednisolone group(Group C) and 5 mg/kg Methylprednisolone group(Group D).Intoxication was induced by intraperitoneal injection of paraquat dissolvent(22 mg/kg) in group B,C,D.Intraperitoneal injection of methylprednisolone(5 mg/kg and 15 mg/kg) was given daily in Group C and D,respectively,while only saline was injected in the other two groups.Six rats in each group were sacrificed at 24th,72nd and 168th hour,for pathological observation of lung tissues by light microscope.Results:Significantly milder pathological change of acute lung injury was observed in Group C and D,compared with that in Group B(P0.05).Significantly lower lung injury score in Group D was revealed at 24th and 72nd hour,compared with that in Group B,whereas only significantly lower score presented in Group C at 24th hour(P0.05).The lowest lung injury score was found in Group A among all 4 groups(P0.05).Furthermore,scores were significantly lower in Group C and Group D than that in Group B(P0.05),though no significant difference was found between the two treatment groups.Conclusion:Methylprednisolone has protective effect on lung injury in rats with paraquat intoxication,with superior efficacy observed in low dosage than in higher dosage.