The Expression Of VEGF, β-catenin, DKK-1 Proteins In Neonatal Rat Lung After Hyperoxia Exposure

Objective :1. To establish a neonatal rats model of hyperoxia- induced lung injury;2. To observe the general condition and the pathologic changes in lung tissue of ratsin each group and the levels of protein of VEGF,β-catenin, DKK-1 in the pathogenesis of acute hyperoxia-induced lung injury;3. To investigate whether DKK-1 as the Wnt signaling pathway inhibitor could protect against hyperoxia-induced lung injury.And providing information for the prevention and treatment of hyperoxic lung injury in neonates.Methods:Thirty-six neonatal rats that the age less than 6 hours after birth were randomly assigned to two groups:Group Ⅰ:control group(n=18);Group Ⅱ:hyperoxia group(hyperoxia, n=18);The rats of Group Ⅰwere exposed to normoxia(room air) and the rats of group Ⅱ were exposed to hyperoxia(more than 95% oxygen)in a specially constructed boxes.Each group was divided into 3 subgroups,the 1day, 3 day and 7 day.Twelve rats from each subgroup were randomly selected, and killed to measure the following indices:(1). Lung wet-to-dry ratio:The left lung were isolated and weighed,then the dried lungs were weighed,and calculated the lung wet/dry ratio;(2). Lung histology:Lung sections from the right lung were stained with HE,and examined for the histological changes;(3). The protein expression of VEGF,β-catenin, DKK-1:Western blotting were used to detect the protein expression of VEGF,β-catenin, DKK-1;Results: 1.The general condition of the rats in each group: Control group, the growth of rats was in normal,and no death.After three days of hyperoxia group,the respiratory rate of rats accelerated without hyperoxia.After seven days,the experimental animals’ spirit was dispirited,showed dyspnoea,cyanotic without hyperoxia,the rats appears dull, poor mental reactions,and irritability, dyspnea obviously, lip cyanosis without hyperoxia, no individual rats died in the absence ofhyperoxia.2. The pathological morphology of lung tissue: No pathological change were found in the lung of rats in normoxic controls,the alveolar contains no inflammatory cells and exudation. The hyperoxia group, at 3th day, vascular congestion, interstitial edema,inflammatory infiltrates were found. At 7th day,pulmonary edema, structural disorder,lungdysplasia, alveolar simplification, tinner septa and walls of alveoli and decreased alveoli numbers.3.The lung wet / dry weight ratio(W / D): at 1thday, 3th day, 7th day, the lung W / D ratio was higher in the hyperoxia groups than the control group(P <0.05).4.The expression of VEGF,β-catenin, DKK-1 protein in lung tissue:(1). At 1th day, The expression level of VEGF proteinin the hyperoxia group is increaseded compared with that in the control group(P <0.05); At 3th day, 7th day, the expression of VEGF protein in the hyperoxia group was decreased compared with that in the control group(P <0.05).(2). At 1th day, The expression level of VEGF,β-catenin proteinin the hyperoxia group is nearly compared with that in the control group(P>0.05). At 3th day, the expression of β-catenin protein in the hyperoxia group was decreased compared with that in the control group(P <0.05); At7 th day, the expression of β-catenin protein in the hyperoxia group was significantlydecreased compared with that in the control group(P <0.05).(3). At 7th day, the expression of DKK-1 protein in the hyperoxia group was increased compared with that in the control group(P <0.05); At 1th day, 3th day, the expression level of DKK-1 proteinin the hyperoxia group is nearly compared with that in the control group(P>0.05).Conclusions: 1. Exposed to hyperoxygen will cause lung injury in rats, and the injury will increase with the extension of hyperoxia time.The main histopathological of lung tissue are lungdysplasia, alveolar simplification, thinner septa and walls of alveoli and decreased alveoli numbers.2.The expression of VEGF,β-catenin in the lung of rats with hyperoxia-induced lung injury decreased significantly compared with those in room air,that coincided with alveolar structure degradation.The results suggests that the changes in the expression level of VEGF and β-catenin may be responsible for lung development in the rats with acute hyperoxia-induced lung injury.3. The expression level of DKK-1 increased firstly and then decreased. The level is parallel with the degree of lung injury. These findings suggest thattheexpression level of DKK-1 protein plays an important role in hyperoxia-induced lung injury.