The expression and significance of Smad4 and Smad7 in newborn rats with hyperoxia-induced chronic lung diseases / 中国小儿急救医学

ABSTRACT

Objective To investigate the expression and significance of Smad4 and Smad7 in newborn rats with hyperoxia-induced chronic lung disease(CLD).Methods Sixty-four newborn Wistar rats 12 h after birth were divided into high-oxygen group (n =32) and air group (n =32,control group) by random number table method.The high-oxygen group was placed in the oxygen glass tank with continuous infusion of oxygen.And 1,3,7,14 d after experiment,tracheal separated,the chest opened to expose heart and lung,slices were Masson staining,undergo dynamic observation of the pulmonary pathological changes under light microscope.Lung fibrosis score was carried out to determine the degree of pulmonary fibrosis,and immunohistochemical technique was used to detect Smad4 and Smad7 protein expression in lung tissue.The expression levels of Smad4 and Smad7 protein in lung tissue were detected with Western blot.Results Compared with the air group,there was statistically significant difference in pulmonary fibrosis score on day 7 (2.67 ± 0.21 vs 0.58 ± 0.17) and day 14 (4.48 ± 0.24 vs 0.63 ± 0.13) in high-oxygen group (P ＜ 0.05) ; Smad4 and Smad7 was main in visible lung epithelial cells and interstitial fibroblasts.Smad4 expression in the high-oxygen group gradually enhanced,compared with the air group (P ＜ 0.05) on day 7 (122.35 ± 10.3 vs 140.08 ±7.77) and day 14(129.7 ± 7.33 vs 144.99 ± 6.49).Smad7 expression in the high-oxygen group first increased and then decreased,expression in the high-oxygen group increased on day 7 (122.35 ± 10.29 vs 130.56 ±9.8),and compared decreased with the air group(P ＜0.05) on day 14(132.16 ±4.38 vs 126.22 ±6.49).Conclusion The newborn rat exposed hyperoxia,the up-regulation of Smad4 protein expression and the down-regulation of Smad7 protein expression are imposible closely related to the happen and development of CLD pulmonary fibrosis.