A Study On The Inhibitory Effect Of Rapamycin Against In Premature Rats Oxidative Lung Injury Fibrosis Repair Process Via MTOR Signaling

Objective To investigate the expression of TGF-?,CTGF and COL1 and mTOR pathway downstream target protein 4EBP1 and P70S6 K after rapamycin and hyperoxia intervention,and to investigate the impact and mechanism of mTOR signal pathway and its inhibitor rapamycin in premature rats with hyperoxia-induced lung injury.Methods The lung injury model of neonatal premature rats was induced by 90% oxygen.The lung tissue of normal air group?hyperoxia 3/7/14 d group?air + rapamycin group?hyperoxia 3/7/14 d + rapamycin group was observed under light microscope,The expression of TGF-?,CTGF and COL1 was assessed using ELISA and The protein expression and gene expression of mTOR pathway Complex mTORC1 and downstream target protein 4EBP1,P70S6 K using Western blot and RT-PCR.Results 1?Pathological and pathological changes of lung tissue: The hyperoxia 3/7/14 d group had lower body weight of premature rats than normal the air group;Light microscopic observation found that The lung tissue nucleus and cytoplasm is clear,evenly distributed,no pathological changes in the normal air control group;the lung tissue nucleus is clear,but have a little inflammatory cells,alveolar septa began to break in the hyperoxia 3d group;alveolar septal fracture serious,alveolar fusion began to appear,a lot of inflammatory cell infiltration inthe hyperoxia 7d group;the lung tissue was reticular distribution,trachea,blood vessels and other thickening phenomenon,the cytoplasm of cytoplasmic clutter,a large number of lung fibroblast proliferation in the hyperoxia 14 d group;The lung tissue was no pathological change in normal air+ rapamycin group;the lung tissue cytoplasm and nucleus is clear and evenly distributed,the trachea,and pulmonary artery and so clear and normal,a few alveolar septal fracture in the hyperoxia 3d+ rapamycin group;the trachea,and arteries is thickening,the cytoplasmic is distribut disorders,the alveolar is fusion in the hyperoxia 7d+ rapamycin group;the cytoplasm and nuclear is distribut disorders,alveolar septum is extensive fracture,alveolar is serious fusion in the hyperoxia 14d+rapamycin group.The pathological score of lung tissue in hyperoxia3/7/14 d group was obvious higher than that in air control group(p<0.01);The level of pathological score was positively correlated with oxygen intake time,the highest score was observed at hyperoxia 14 days;The pathological score of lung tissue in premature rats in the high-oxygen3,7d + rapamycin group were lower than those the point alone hyperoxia exposure group at the same time(p<0.05),the difference was statistically significant;but there was no significant difference between high-oxygen14 d + rapamycin group and hyperoxia 14 d group(p>0.05).2?The expression of TGF-?,CTGF and COL1 in each group lung tissue of premature rats was assessed using ELISA:The expression of TGF-?,CTGF and COL 1 in lung tissue of premature rats after 3/7/14 days of hyperoxia exposure were significantly higher than those in air control group(p<0.05),The longer the hyperoxia exposure time,higher the content of TGF-?,CTGF and COL1;The expression of TGF-?,CTGF and COL1 in the high-oxygen3/7/14 d + rapamycin group were lower than those the point alone hyperoxia exposure group at the same time(p<0.01).3 ? The protein and m RNA expression of mTORC1,P70S6 K and4EBP1 protein in each group lung tissue of premature rats : the expression of mTORC1,P70S6 K and 4EBP1 protein in the high oxygen3 d + rapamycin group decreased,compared with the high oxygen group,the difference was statistically significant(p <0.05).The expression levels of mTORC1,P70S6 K and 4EBP1 protein in the high-oxygen 7,14 d +rapamycin group were lower than those in the high-oxygen 3d +rapamycin group(p<0.01);the expression of mTORC1,P70S6 K and4EBP1 m RNA in the high oxygen 3d + rapamycin group decreased,compared with the high oxygen group,the difference was statistically significant(p <0.05).The expression levels of mTORC1,P70S6 K and4EBP1 m RNA in the high-oxygen 7,14 d + rapamycin group were lower than those in the high-oxygen 3d + rapamycin group(p<0.01).conclusion 1?The premature rats were exposured by 90% concentration of oxygen,its lung tissue congestion,pulmonary septal fracture,pulmonary fibroblast hyperplasia.The levels of TGF-?,CTGF and COL 1were increased at the same time,prompting that TGF-?,CTGFand COL 1were involved in hyperoxia Lung injury fibrosis repair process.2 ? rapamycin can reduce the lung tissue-related fibrosis factor TGF-?,CTGF synthesis,while improving the early prenatal hyperoxic lung injury early pathological damage,may be used as one of the early prevention of early BPD drugs.3?rapamycin can inhibit the activation of mTOR signaling pathway and the expression of upstream and downstream molecular mTORC1,P70S6 K and 4EBP1,which may be one of the mechanisms to alleviate pulmonary fibrosis in early hyperoxia-induced lung injury.