Protective Effects Of VEGF On Hyperoxic Lung Injury In Neonatal Rats

Objective To explore the effects and mechanisms of vascular endothelial growth factor (VEGF) on hyperoxic lung injury in neonatal rats so as to provide experimental and theoretical evidences for preventing and treating bronchopulmonary dysplasia in neonatal.Methods a total of 24 3-day-aged Sprague-Dawley rats were randomly divided into 3 groups: GroupⅠair + normal saline;Ⅱhyperoxic + normal saline;Ⅲhyperoxic + VEGF.groupⅡand groupⅢwere exposed to 90～95% oxygen, while groupⅠwere exposed to room air. groupⅡand groupⅢunderwent intramuscular injection of VEGF in dose of 20μg/(kg.d) for 7 days while groupⅠreceived the same dose of normal saline.At postnatal day 22 all animals were killed, The lung wet weight/dry weight ratio(W/D) , radical alveolar counts were determined and the intension of CD34 expression in rat lung was analyzed by the method of immunohistochemistry, and lung hhistopathological changes were examined in all groups.Results (1)After 22 days,compared with groupⅠ,groupⅡshowed lunginjury characterized by the increase in W/D,while the decrease in theradical alveoliar counts and the intension of CD34 expression.( 9.6±1.1vs16±1.1,P<0.01) (2) compared with groupⅡ, the intension of CD34 expression in rat lung of groupⅢwas increased (17±1.3vs9.6±1.1,P<0.01),and the radical alveolar counts also increased(11±0.9vs6.6±1.1, P<0.01).but the W/D was decreased.Conclusions (1) Exposure of neonatal rats to 90～95% oxygen impairs lung growth as characterized by decreased alveoliar number and vascular density and that these changes persist despite recovery in room air. Treatment with rhVEGF improves lung architecture as demonstrated by increased alveoliar number and vascular density.