Effects Of COX-2 Inhibitor On Lung Tissue Protective Mechanism And Expression Of AQP-1 And NF-κB In Lung Tissue Of Hyperoxic Neonatal Rats

Objective:1.Choosing the suitable newborn Sprague Dawley(SD)rats for the test of hyperoxic lung injury,and observe their pathological changes of lung tissue.2.Compared the expression trend of aquaporin-1(AQP-1)and nuclear factor kappa B(NF-kappa B)in hyperoxia induced lung injury,study the role of AQP-1,NF-kappa B in the pathogenesis of lung injury.3.Observed whether the inhibitor of cyclooxygenase 2(COX-2),Celecoxib,can protect the lung tissue from hyperoxia injury and provide the basis for prevention and treatment of lung injury in hyperoxia environment.Method:1.We choose the suitable newborn Sprague Dawley(SD)rats for the test of hyperoxic lung injury: select 105 newborn Sprague Dawley(SD)rats(male or female)which are with one day of birth,divide them into three groups:Group I: Air group(air + intraperitoneal injection of DMSO);Group II: Hyperoxia group(85% oxygen + intraperitoneal injection of DMSO);Group III: Celecoxib intervention group(85% oxygen + intraperitoneal injection of celecoxib).2.Group I,let the newborn rats freely breathing air,and do the injection of DMSO(5ml / kg at a fixed time of each day).And then put the newborn rats of Group Ⅱ and group Ⅲ into a closed tank with 85% hyperoxia.For Group Ⅱ,the rats were injected with DMSO(5 ml / kg)at a fixed time from the first day of the test.For groupⅢ,they were injected of celecoxib 5mg / kg at the same time point from the first day of test.3.Choosd 8 rats from each of the group of 3d、7d、14d randomly and kill them,take their lung tissue as samples for test:(1)Observe the morphological changes by hematoxylin-eosin(HE)staining in the lower right lung tissue.(2)For the right upper lung tissues,observe the AQP-1 and NF-kappa B content in lung tissue by Immunohistochemical staining for prat of the tissues,for another part of them,observe the growth and development of lung tissue cells by apoptosis staining.Results:1.The general situation of each group of rats during the test:Group I: Air group,the rats grow well,normal,no death.;Group II: Hyperoxia group,it appears adverse symptoms gradually,such as,apathetic,unresponsive,the activity significantly reduced,breath difficult without oxygen,agitated activity significantly,four pieces are dead during the test.;Group III: Celecoxib intervention group,the general situation was significantly improved than the Hyperoxia group,1 is died during the test.2.The Pathological changes of lung tissue: Group Ⅰ(air group)rats,the size of the alveolus in lung tissue was same at each time points,and the structure was complete,no alveolar and inflammatory cell infiltration was found in the alveolar cavity.The morphological changes of lung tissue in group Ⅲ(Celecoxib intervention group)were significantly higher than those in Hyperoxia group in each time point.In the group Ⅱ(Hyperoxia group),there were fluid exudation,pulmonary telangiectasia,alveolar cavity enlargement and infiltration of inflammatory cells in the cavity after 3d for Hyperoxia exposure,after 7d,there was bleeding in the alveolar cavity,liquid exudation is more,inflammatory cell infiltration is significantly heavier than 3d,lung tissue disorder,part of the alveolar cell damage and have pulmonary bullae.after14,the structure damage of lung tissue was much more obviously,the alveolar-capillary membrane and pulmonary septum were more thick,there was fibrous manifestations of fibroblastic proliferation.The morphological changes of lung tissue in group Ⅲwere significantly higher than those in hyperoxia group.3.The expression of AQP-1 and NF-κB protein for lung tissue:at each time point,compared the Group II hyperoxia group(group Ⅱ)with the air group(group Ⅰ),the expression of AQP-1 protein in lung tissue was significantly decreased(P <0.01),the expression of NF-κB protein was significantly increased(P <0.01).The expression level of AQP-1 protein in the lung tissue of the group Ⅲ was significantly higher than that in the Hyperoxia group(group Ⅱ)(P <0.01),and the expression of NF-κB protein was significantly decreased than group Ⅱ(P <0.01).4.The changes of alveolar cell apoptosis in air group,hyperoxia group and intervention group: at each time point,compared the Group II hyperoxia group(group Ⅱ)with the air group(group Ⅰ),the number of apoptotic cells in lung tissue was significantly increased(P <0.01).The number of apoptotic cells in lung tissue of group Ⅲwas significantly lower than that in hyperoxia group(group Ⅱ)(P <0.01).Conclusion:1.Breathing with high concentrations of oxygen for long time will make the newborns rats with lung injury,such as,alveolar inflammatory fluid exudation and inflammatory cell infiltration;lung tissue disorder,alveolar-capillary membrane,pulmonary septum was thickened,Cell proliferation and so on.2.With the hyperoxic lung injury,the expression of AQP-1 protein was significantly lower than that in the air group,it showed that it may have alveolar epithelial cell membrane damage or dysfunction with the hyperoxic lung injury.The expression of NF-κB protein was significantly higher than that of the air group,it showed that it’s very important in the process of lung injury.3.With the hyperoxic lung injury,the number of apoptotic cells in lung tissue was significantly higher than that in the air group,and the number of normal alveolar cells was significantly decreased.It showed that too much oxygen could cause the damage of alveolar cells,reduce the life span of normal cells,and accelerate the cell apoptosis;4.For the newborn rats in the high oxygen environment,the intraperitoneal injection of celecoxib will promote the expression of AQP-1 protein,inhibite the activation of NFkappa B,reduce the expression of inflammatory cytokines,reduce the damage of alveolar epithelial cell,inhibit the apoptosis of normal cells,has a protective effect on hyperoxia induced lung injury.