2008•Zhongguo xiaoer jijiu yixueRequires access
Effect of dexamethasone on aquporin-1 expression in the long of hyperoxia-exposed newborn rats
Guobing Chen, Feng Xu, Zhong-Yi Lu
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Abstract
Objective To investigate the effect of dexamethasone on aquporin-1(AQP1) expression in the lung of hyperoxia-exposed newborn rats and to explore the protective mechanism of dexamethasone in lung injury.Methods Thirty-two newhorn Wistar rats were randomly divided into 4 groups:room-air group, hyperoxia-exposure group, room-air group treated with dexamethasone and hyperoxia-exposure group treated with dexamethasone. Lungs were harvested on the third day. The lung AQP1 mRNA expression and the protein location were detected by reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry. In addition, the wet-to-dry weight ratio(W/D), the protein content of broncho alveolar lavage fluid (BALF), lung permeation index and histological changes in lung were measured respectively. Results On the third day after hyperoxia-exposure, lung tissues appeared congestion, inflammatory cells exudation and edema. The lung W/D, the protein content in BALF and the lung permeation index in hyperoxia group were significantly higher than those in room-air group. In contrast, lung injury degree relieved in hyperoxia group treated with dexamethasone, The expressions of AQP1 mRNA in room-air group, hyperoxia group and hyperoxia group tteated with dexamethasone were 0.70 ±0.04, 0.42 ± 0.03 and 1.04 ± 0.04 respectively, and there was aignificant difference ( all p < 0.05). Compared with room-air group, the expressions of AQP1 mRNA was lower than that in hyperoxia group, while the expression was upregulated in hyperoxia group treated with dexamethasone. The changes of AQP1 protein level was persistent with the changes of AQP1 mRNA expression. Conclusion The expressions of lung AQP1 downregulates in hyperoxia-induced lung injury. Dexamethasone can upregulates the expressions of lung AQP1, which might be one of the protective mechanisms against hyperoxia-induced lung injury.
Key words:
Aquaporin-1; Hyperoxia; Lung injury; Dexamethasone; Newborn rat