The Effect And Significance Of RhEPO To The Expression Of BCL–2 And Caspase-9 In The New Type BPD Model,s Lung Tissue

Objectives:(1) To study the effect of recombinant human erythropoietin(rhEPO) on lung tissue pathological changes and BCL-2 and caspase-9 protein and mRNA expression in new type bronchopulmonary dysplasia(BPD) model.(2) To explore the role of phosphatidylinositol 3-kinase/protein kinase B(PI3K/AKT) pathway in rhEPO protecting new type BPD.Methods : Injected lipopolysaccharide(LPS)or normal saline(NS)to Sprague-Dawley(SD) rats, gestational sacs on 15 th day of gestation. The neonatal rats of NS group were devided into A,B,C three groups, respectively to deal with air(oxygen concentration 21%), hyperoxia and hyperoxia+rhEPO. The air disposal group as control group. The newborn rats of LPS group were devided into D,E,F three groups, respectively to deal with hyperoxia, hyperoxia+rhEPO and hyperoxia+rhEPO+LY294002.The hyperoxia groups were exposed to 60% high oxygen. Since the first day of hyperoxia exposure, C group、E group and F group,s neonatal rats were injected rhEPO(1 200IU/kg) on back subcutaneous every other day, The F group,s neonatal rats were injected LY294002(0.3 mg/kg)on back subcutaneous 30 minutes before injection of rhEPO, 7 times in total. Randomly killed 8 samples and got lung tissues from each group at 1st,7th and 14 th day after experiment. Lung tissue pathological changes were observed by HE. The levels of Bcl-2 and Caspase-9 protein expression were detected by Western blot, and the levels of Bcl-2 and Caspase-9 mRNA expression were detected by RT-PCR.Results: In the B group and D group,s neonatal rats lung tissue, the pathological changes obviously, and the levels of Caspase-9 protein and mRNA expression was increased, while BCL-2 protein and mRNA expression was decreased.In the C group and E group,s neonatal rats,lung tissue pathological changes have improved markedly, and BCL-2 protein and mRNA expression was increased, while Caspase-9 protein and m RNA expression was decreased. Compared F group with E group, The former neonatal rats lung tissue pathology changes worse, and Caspase-9 protein and mRNA expression was increased obviously, while BCL-2 protein and mRNA expression was decreased obviously. The differences of lung tissue BCL-2 and Caspase-9 protein and mRNA expression between each group had statistically significant on 1st、7th and 14 th day after experiment(P<0.05).Conclusions: Intrauterine inflammatory and hyperoxia exposure after birth can cause bronchopulmonary dysplasia, and lead to lung tissue BCL-2, Caspase-9 protein and mRNA expression changes obviously at the same time. While rhEPO can significantly reduce the lung tissue pathological changes, increase the BCL-2 expression, and reduce the Caspase- 9 expression, When the active of PI3 K was inhibited by LY294002, the role of rhEPO protect new type of BPD is decreased obviously. Suggest rhEPO have certain control effect on BPD possibly by reducing the pulmonary apoptosis and improve lung development eventually. The mechanism maybe associated with PI3K/AKT signal transduction pathway.