Effects of methylprednisolone on pneumocyte apoptosis during pulmonary ischemia/reperfusion injury in rats

Objective:To investigate the effects of methylprednisolone(MP)on pneumocyte apoptosis during lung ischemia/reperfusion injury in rats and to study the possible role of MP in pneumocyte apoptosis.Methods:Forty-two male Sprague-Dawley rats used for unilateral lung ischemia/reperfusion model were randomly divided into three groups:sham operation group(Sh group),ischemia/reperfusion group(I/R group),and methylprednisolone group(MP group).Each group has two subgroups of three hours and six hours.Apoptosis rate in lung tissue was detected by the way of Annexin-V-PI in flow cytometer.Expression of IκB-α in lung was observed by immunohistochemical stain.The index of quantitative assessment of histological lung injury(IQA),the wet to dry weight ratio(W/D),the pathological and ultrastructure changes of lung tissue were measured.Results:Apoptosis rate,W/D,IQA of lung tissue were significantly higher in I/R group than which in Sh group(P0.01),while the expression of IκB-α in lung was obviously lower in I/R group than which in Sh group(P0.01).Apoptosis rate of lung tissue was significantly correlated with IQA level of lung tissue(r=0.971 4,P=0.000 3).But it had negative correlation between apoptosis rate of lung tissue and IκB-α level of lung tissue(r=-0.892 9,P=0.006 8).MP group had more significant change in apoptosis rate、the expression of IκB-α、W/D、 IQA of lung tissue than which in I/R group(P0.05).The pathological and ultrastructure changes of lung tissue were better in MP group than which in I/R group.Conclusion:Cellular apoptosis play more important role in the pathological and physiological process of pulmonary ischemia/reperfusion(I/R)injury.In the early period apoptosis rate changes following the changes of inflammatory reactions.MP inhibits the apoptosis of lung I/R injury,extenuates the degree of lung I/R injury by the possible mechanism of decreasing the activation of IκB-α in the early period of lung I/R injury.