Effects Of Different Does Methylprednisolone On Early Lung Injury In Paraquat Toxic Rats

Objective:To study the intervention effects of Methylprednisolone on lung injury of rats with paraquat intoxication.To find methylprednisolone treatment of acute lung injury in paraquat poisoning the best dose. For the hormone in the clinical treatment of acute paraquat poisoning to provide reference.Methods:Adopt intraperitoneal injection of 20% PQ solution as the rat model of acute paraquat poisoning.120 Wistar rats were randomly divided into 5 groups:normal control group(group A),intoxication group(group B),5mg/kg Methylprednisolone group (group C),15mg/kg Methylprednisolone group(group D) and 30mg/kg Methylprednisolone group(group E).Group B and groupC, D, E were given PQ solution at dose of 22mg/kg by intraperitoneal injection for once. After the exposure of 2h, group C, D, E were peritoneal injected theMethylprednisolone at dose of 5mg/kg,15mg/kg,30mg/kg,1/d. The group A and group B were peritoneal injected respectively with the equivalent volume of normal saline,1/d. The experimental animals were executed in batches by each group at 24 h,72 h,168h.Before the rats were executed, the ketamine injection is injected into the abdominal cavity of rats and the rats were anesthetized, opened the abdominal cavity through the abdominal aorta to obtain arterial blood, to measure partial pressure of oxygen in arterial blood oxygenation index calculation; open the chest to get left and right lungs and produce lung biopsy and calculate the lung coefficient;observe the pathological changes of lung tissue characteristics in the microscope, lung coefficient and changes in oxygenation index.Results:l.The observation of the lung tissue pathology in the light microscope show that, groupC,D,E compared with the group B, the pathological changes of acute lung injury such as alveolar hemorrhage, exudation, inflammatory cell infiltration, alveolar septal infiltration of inflammatory cells are relatively mild. Group C and group E is the lighter of pathological injury. In each group the semi-quantitative score in pathology at the same time show that:compared with group B and group D, group E and group C were the lower (P<0.05); but there is no difference between the comparison of the group C and group E in the two time points (72h,168h) (P>0.05)2.Compared with normal control group(group A), group B,group C,group D,group E's lung index at each point have significantly differences(P<0.05);compared with the PQ treated group (group B),different doses of methylprednisolone treatment group (group C, D, E) lung coefficients have significant differences at the same time point.(P<0.05);at the 24h point, there is no significant difference in lung index between group C and group D(P= 0.072>0.05) and there are significant differences in lung index between group C, group D and group E (P<0.05); at the 72h point, there are significant differences in lung coefficient by the comparison of group C,D and group E(P<0.05), while there is no significant difference in lung index between the group C and group D (P= 0.151> 0.05); at the 168h Point, there is no significant difference in lung index among the group C, group D and group E (P=0.297, P=0.555, P=0.109)3.Compared with the group PQ (group B), different doses of methylprednisolone intervention group's(group C, D, E) oxygenation index was significantly different at the same point.(P<0.05);the pairwise comparison of group C, D, E show that there is no significant difference in oxygenation index at 24h,72h,168h time point(P>0.05) without any statistical significance.Conclusion:1. The results suggest that methylprednisolone on acute lung injury in rats with paraquat poisoning has a protective effect.in improving thepulmonary edema, inflammation,oxygenation indices.2. The efficacy of methylprednisolone and the dose of methylprednisolone relationship are not linear in the treatment of early lung injury of PQ poisoning rats.3.30mg/kg methylprednisolone effect is best in three different does for the PQ poisoning rats in 24 hours.4. the efficacy of 5mg/kg methylprednisolone has some advantages for the PQ poisoning rats in 72-168 hours.