We studied the effects of chronic hyperoxia (>95% oxygen for 14 days) in change of body weight, wet to dry lung weight ratio, and morphologic changes of lung tissue compared with that of room air (21% oxygen for 14 days) in Sprague-Dawley
neonatal
rat
pups.
@ES The results were as follows:
@EN 1) In neonatal rat pups exposed to room air (normoxia group), body weight of initial 3 days of neonatal rat pups was 9.18 0.18g, and body weights of developing rat pups exposed to room air for 7, 10, 14 days were 14.07 1.90, 17.00 2.09, 23.07
1.93g
respectively. In neonatal rat pups exposed to hyperoxia (hyperoxia group), body weight of initial 3 days of neonatal rat pups was 9.35 0.80 g, and body weights of developing rat pups exposed to hyperoxia for 7, 10, 14 days were 11.06 1.31, 12.64
1.77,
15,41 1.65 g respectively. These results suggest that changes of body weight in developing rat pups were stunted significantly in the hyperoxia group compared with normoxia group during 14days-experiment (p<0.01).
2) No appreciable difference of wet to dry lung weight ratio was noted at initial 3 days of neonatal rat pups between normoxia group and hyperoxia group, but considerably increased wet to dry lung weight ratio was noted significantly at 7 days of
exposure in the hyperoxia group compared with the normoxia group (p<0.05). The difference of wet to dry lung weight ratio was not significant at 10, 14 days of exposure between normoxia group and hyperoxia group. These results suggested that
relative
water content of wet lung was at a peak at 7 days of exposure in hyperoxia group.
3) The lung from developing rat pups exposed to room air for 7 days had many small alveoli and numerous septal buds. However, in the lung from developing rat pups exposed to hyperoxia for 7 days, presence of pink staining material within the
lumen
of
the air spaces (proteinaceous edema fluid) and increased interstitial cellularity due to infiltration by macrophages and neutrophils was observed, and these findings suggested acute exudative lung injury.
4) In most lungs from developing rat pups exposed to room air for 14 days, much increased alveolarization including the secondary septal bud formation was observed. However, in most lungs from developing rat pups exposed to hypeoxia for 14 days,
increased septal and interstitial cellularity and thickness and interstitial fibrosis were observed significantly compared with normoxia group (p<0.01).
In conclusion we could make a experimental animal model which had similar histopathologic finding of bronchopulmonary dysplasia in human infant and this model will be useful for research of pathogenesis of bronchopulmonary dysplasia.
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