Abstract: Objectivs To study the effects of dexamethasone in different time on lung pathological morphology changes and growth development in neonatal rats which injury of hyperoxia, in order to providing the theoretical reference of dexamethasone to prevent and cure bronchopulmonary dysplasia (BPD). Methods The Wistar neonatal rats were designed in eight groups by random including:air group;hyperxia group;hyperxia group with early dexamethasone group and later dexamethasone group.Body weight, general situation and the death number of rats, the degree of pulmonary edema, alveolarization block and pulmonary fibrosis from lung coefficient calculation, alveolar interval thickness, radical alveoli count (RAC)and pulmonary fibrosis stocker score were recorded. Results The hyperxia group rats showed serious lung injury after exposed 95% oxygen.The general situation of early dexamethasone group rats was the worst and the degree of pulmonary edema, alveolarization block and pulmonary fibrosis were the most serious.The general situation of the later dexamethasone group was better and the growth increased faster than hyperxia group.But there had not significant differences in lung coefficient calculation, RAC, alveolar interval thickness and pulmonary fibrosis stocker score between the later dexamethasone group and the hyperxia group. Conclusions Early use dexamethasone has no action to prevent BPD, instead it may aggravated the hyperxia lung damage.Dexamethasone couldn't suggest as prophylaxis for BPD, dexamethasone should be used in the late therapy stages, and as small doses and short treatment as possible.

Key words: hyperoxia, lung injury, dexamethasone, bronchopulmonary dysplasia, neonatal rat

摘要： 目的 观察不同时间使用地塞米松对新生大鼠高氧肺损伤及生长发育的影响, 以期为在支气管肺发育不良(bronchopulmonary dysplasia, BPD)的防治过程中能否使用地塞米松提供理论依据。方法 将新生Wistar大鼠随机分为空气组、高氧组、早期地塞米松组、晚期地塞米松组。观察记录各组大鼠一般状况、体重及死亡情况。观察各组大鼠肺组织发育、肺水肿及肺泡化阻滞程度。结果 新生大鼠生后肺仍处于持续发育阶段, 暴露于95%氧可出现高氧肺损伤及肺发育阻滞;早期地塞米松组大鼠的一般状况最差, 其肺水肿、肺泡发育阻滞程度最严重。晚期地塞米松组大鼠一般状况好转, 体重增长率较高氧组及对照组快, 但与高氧组比较, 肺系数、RAC值及肺间隔厚度差异无统计学意义。结论 早期使用地塞米松没有预防BPD的作用, 且会加重高氧肺损伤。建议不要将地塞米松作为BPD的预防性用药, 在使用地塞米松治疗BPD的过程中, 应在晚期使用, 并尽可能使用小剂量、短疗程。

关键词: 高氧, 肺损伤, 地塞米松, 支气管肺发育不良, 新生大鼠