Expression of Notch in hyperoxia induced lung injury in newborn rat

Objective To observe the expression of Notch 1 3 and Jagged in lungs of newborn rats exposed to hyperoxia and explore the role of Notch in hyperoxia induced lung injury. Methods Eighty neonatal SD rats with 22 days of gestational age were randomly assigned to control group and hyperoxia group. After 1,7,14 and 21 days of continued exposure to oxygen ( n =40, oxygen 0.85) or room air ( n =40) respectively, six rats of each group were used to assess lung histologic changes with HE staining and expression of Notch in lungs with immunohistochemistry. Total RNA was extracted by Trizol reagent from the frozen lung tissues. mRNA levels of Notch were measured by reverse transcription polymerase chain reaction (RT PCR). Results 1. Hyperoxia group showed lung injury characterized by subacute alveolitis and inhibition of lung development at 7,14 and 21 days after birth from the lung histology exam. 2 Positive staining for Notch 1, Notch 2 and Jagged in hyperoxia group was much lower than control at every time point ( P0.01,P0.05 ), but the hyperoxia group showed higher expression of Noth 3 than control ( P0.05 ). Notch was strongly expressed in airways epithelial, alveolar epithelial and inflammatory cells, and fibroblast in hyperoxia group ( P0.01 ). 3. Notch mRNA levels were changed similarly as protein level ( P0.01 ).Conclusions 85% O 2 prolonged exposure resulted in the decrease of Notch, which is likely to contribute to the pathogenesis of hyperoxic lung injury in newborn rats.