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目的研究高氧暴露下,早产大鼠皮质醇(GC)动态变化,探讨其与支气管肺发育不良(BPD)发生之间的关系。方法妊娠21d剖宫产娩出的早产大鼠随机分为实验组和对照组,实验组大鼠持续吸入>90%O2,对照组大鼠呼吸空气。于生后1d,3d,7d,14d,和21d取肺组织行HE染色。于生后3d,7d和14d,从两组中随机选取仔鼠断头取血,应用放射免疫法测定血清皮质醇浓度。结果对照组早产大鼠血清皮质醇浓度在检测的各时间点无显著性改变,实验组大鼠的血清皮质醇浓度在生后3d时与对照组比较无显著性差异(n=25,P=0.56),在生后7d时显著高于对照组(n=25,P=0.04),在生后14d时显著低于对照组(n=21,P=0.0018)。高氧组早产鼠肺脏表现出BPD样病理改变,各时间点高氧组辐射状肺泡计数明显低于对照组(P<0.05),生后3d,7d,14d和21d时,高氧组肺纤维化评分明显高于对照组(P<0.05)。结论高氧暴露可以导致早产大鼠肺纤维化,影响肺发育。早产大鼠的血清皮质醇浓度在高氧暴露时有明显改变,可能参与肺损伤的发生过程,影响糖皮质激素的疗效。
Objective To investigate the dynamic changes of cortisol (GC) in premature rats under hyperoxia exposure and to explore its relationship with the occurrence of bronchopulmonary dysplasia (BPD). Methods Premature delivery of cesarean section on pregnancy 21d was randomly divided into experimental group and control group. The rats in experimental group continued to inhale more than 90% O2, and the control group rats breathed air. The lungs were harvested at 1d, 3d, 7d, 14d, and 21d after birth for HE staining. At 3, 7 and 14 days after birth, the offspring of the offspring were randomly selected from the two groups, and serum cortisol concentration was determined by radioimmunoassay. Results Serum cortisol levels of preterm rats in control group showed no significant changes at different time points. Serum cortisol concentration of rats in experimental group had no significant difference compared with control group at 3d after birth (n = 25, P = 0.56), which was significantly higher than that of the control group (n = 25, P = 0.04) at 7 days after birth and significantly lower than that of the control group at 14 days after birth (n = 21, P = 0.0018). The lung of premature rats in hyperoxia group showed BPD-like pathological changes, and the number of alveolar pneumocytes in hyperoxia group was significantly lower than that in control group at each time point (P <0.05). At 3d, 7d, 14d and 21d after birth, The score was significantly higher than the control group (P <0.05). Conclusion Hyperoxia exposure can lead to pulmonary fibrosis in preterm rats and affect lung development. Serum cortisol concentrations in preterm rats are significantly altered during hyperoxia exposure and may be involved in the pathogenesis of lung injury and affect the efficacy of glucocorticoids.