Expression Of ICAM-1 In The Lung Of Premature Neonatal Rats Exposed To Hyperoxia And Its Significance

OBJECTIVE:To observe Intercellular Adhesion Molecule 1(ICAM-1) expression in the lung of neonatal premature rats exposed to hyperoxia,we study the internal relationship with ICAM-1 and the lung injury exposed to hyperoxia,providing the new methods to prevention and cure chronic lung disease of premature infants.METHODS:102 neonatal Sprague-Dawley rats of 22-day gestational age were randomized into experimental group and control group,the neonatal rats in experimental group were fed in high concentration of oxygen(inhaled 95%oxygen) and the control groups were fed in the room air.According to the number random method eight neonatal SD rats were respectively extracted as corresponding subgroups at postnatal 3^th,7^th and 14^th day.After extraction,the neonatal rats were executed and got the lung tissues,observing the pathological diagnosis of lung tissues by HE stain,using Masson trichrome stain to assess the interstitial fibrosis severity of lung.The expression of ICAM-1 in lung tissues were analyzed by Immunohistochemical techniques.RESULTS:1.Pathological change of lung tissues:We did not observe visible pathological change in air group at postnatal 3^th,7^th and 14^th day.A great deal of inflammatory cells effusion and thickened alveoli septum were observed in the lung tissues of 7^th hyperoxic group.Decreased Inflammatory cells's numbers and obvious destroyed alveolars,decreased number of alveoli, diverse alveolar size and marked thickened alveoli septum were observed in the hyperoxic group at postnatal 14^th day.2.The extent of lung fibrosis:Masson trichrome stain showed that collagen fibers did not increase in air group and increased markedly in hyperoxic group at postnatal 7^th day and aggravated until 14^th day.3.The expression of ICAM-1 protein:Immunohistochemistry showed that the positive expression of ICAM-1 of the model groups stronger and more extensive than that of the control groups.The model groups positive expression displayed in cytoplasm at alveolar epithelial cell, vascular endothelial cell and tracheal epithelium.The control groups displayed low level.The semiquantitative analysis of ICAM-1 showed that the expression of ICAM-1 were stronger on the postnatal 3^th,7^th and 14^th day in hyperoxic group,the difference was significant compared with air group,P＜0.05.And the highest were day 7.CONCLUSIONS:Hyperoxic exposure can cause lung damage.In the earlier period of hyperoxia exposursion,the expressions of ICAM-1 increased gradually,with continue exposuring,the expression of ICAM-1 descent.It manifests that ICAM-1 plays important role in the early acute inflammation period ofhyperoxia-induced lung injury.