| Objective:To investigate the effect of ischemic postconditioning on early growth response gene-1(EGR-1) expression of ischemia-reperfusion injury of lung in rats and its possible protective mechanisms.Methods:24 rats were randomly allocated to three groups (n=8, each group) after preparation of lung ischemia-reperfusion injury model.①Sham group:Only sham operation (thoracotomy) and no ischemia for 3 h.②Ischemia-reperfusion group (I/R group):Interruption of pulmonary perfusion and ventilation for 1 h followed by reperfusion for 2 h.③Ischemic postconditioning group (IPostC group):ischemic postconditioning (5R/5I, three times) between the end of ischemia and the beginning of reperfusion followed by reperfusion for 1.5 h. Small pieces of lung tissue (about 20mg) were made into homogenate at the end of experiment. The concentration of myeloperoxidase (MPO) in the homogenate was determined. The wet to dry weight ratio (W/D) of the lung tissues was also measured at the end of reperfusion. The lung tissues were prepared for light microscopic observation after reperfusion. RT-PCR was used to detect the expression of EGR-1 mRNA and IL-1βmRNA in the lung tissues.Results:There was statistically significant difference among three groups (P<0.05).①The W/D ratio:Compared with sham group(4.4935±0.4171), the W/D ratio of the lung tissues was significantly increased in I/R group (6.6513±0.3820) (P<0.05).And compared with I/R group, that in IPostC group (5.5151±0.2693) was significantly decreased (P<0.05).②The concentration of MPO:Compared with sham group (1.1847±0.2636), the levels of MPO were significantly increased in I/R group (2.2732±0.5593) (P<0.05). And compared with I/R group, that in IPostC group (1.6317±0.2015) was significantly decreased (P<0.05).③The expression of IL-1βmRNA:Compared with sham group (0.2308±0.0083), it was significantly increased in I/R group(0.5500±0.0281) (P<0.05). And compared with I/R group, that in IPostC group (0.3661±0.0080) was significantly decreased (P<0.05).④The expression of EGR-1 mRNA:Compared with sham group (0.2975±0.0289), it was significantly increased in I/R group (0.6147±0.0152) (P<0.05). And compared with I/R group, that in IPostC group (0.4680±0.0166) was significantly decreased (P<0.05).⑤The lung histological examination showed that the inflammatory responses of the lung tissues in I/R group were significantly severer than those in sham group and that in IPostC group was significantly attenuated compared to I/R group.Conclusion:Ischemic postconditioning can significantly reduce lung ischemia-reperfusion injury. The possible mechanism is that postconditioning may inhibit the expression of EGR-1 and IL-1βand attenuate the inflammatory response in the lung. |
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