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[Effect of hyperoxic exposure on the expression of heme oxygenase-1 and glutamate-L-cysteine ligase catalytic subunit in lung tissue of preterm rats].

OBJECTIVE
To study the effect of hyperoxic exposure on the dynamic expression of heme oxygenase-1 (HO-1) and glutamate-L-cysteine ligase catalytic subunit (GCLC) in the lung tissue of preterm neonatal rats.


METHODS
Cesarean section was performed for rats on day 21 of gestation to obtain 80 preterm rats, which were randomly divided into air group and hyperoxia group after one day of feeding. The rats in the air group were housed in room air under atmospheric pressure, and those in the hyperoxia group were placed in an atmospheric oxygen tank (oxygen concentration 85%-95%) in the same room. Eight rats each were selected from each group on days 1, 4, 7, 10, and 14, and lung tissue samples were collected. Hematoxylin and eosin staining was used to observe the pathological changes of lung tissue at different time points after air or hyperoxic exposure. Western blot and RT-qPCR were used to measure the protein and mRNA expression of HO-1 and GCLC in the lung tissue of preterm rats at different time points after air or hyperoxic exposure.


RESULTS
Compared with the air group, the hyperoxia group had a significant reduction in the body weight (P<0.05). Compared with the air group, the hyperoxia group had structural disorder, widening of alveolar septa, a reduction in the number of alveoli, and simplification of the alveoli on the pathological section of lung tissue. Compared with the air group, the hyperoxia group had significantly lower relative mRNA expression of HO-1 in the lung tissue on day 7 and significantly higher expression on days 10 and 14 (P<0.05). Compared with the air group, the hyperoxia group had significantly lower mRNA expression of GCLC in the lung tissue on days 1, 4, and 7 and significantly higher expression on day 10 (P<0.05). Compared with the air group, the hyperoxia group had significantly higher protein expression of HO-1 in the lung tissue on all days, and the protein expression of GCLC had same results as HO-1, except on day 1 (P<0.05).


CONCLUSIONS
Hyperoxia exposure may lead to growth retardation and lung developmental retardation in preterm rats. Changes in the protein and mRNA expression of HO-1 and GCLC in the lung tissue of preterm rats may be associated with the pathogenesis of hyperoxia-induced lung injury in preterm rats.