The Impacts Of Terbutaline On Expression Of Occludin And TNF-α In Lipopolysaccharide-induced Acute Lung Injury Mice’s Lung Tissue

Objective：To observe the expression of occludin and TNF-α inlipopolysaccharide-induced acute lung injury mice’s lung tissue andimpacts of terbutaline on their expression, and to discuss terbutaline’sprotective effect on lung injury. Methods: A mice model of acute lunginjury by intraperitoneal injection of lipopolysaccharide was established.35healthy male Kunming mice, which were pyrogen-free and weighfrom26to32gram, were divided randomly into three groups: thelipopolysaccharide group, terbutaline group, and normal control group,8mice in each group.5mice were killed at the time points of2h,4h and8hrespectively for the lipopolysaccharide group and the terbutaline group.Taking1mL of saline solution for the normal control group and1mL ofpolysaccharide (with LPS6mg/kg) for the lipopolysaccharide group andthe terbutaline group respectively by intraperitoneal injection. drippingslowly terbutaline of0.25mg/kg into intratracheal of mice in terbutalinegroup for about10minutes. The mice in the lipopolysaccharide groupand control group were treated by sterile saline instead of terbutaline.The PaO2were tested at0h (before modeling),4h for each group. The mice in the control normal group were executed at4h. After PaO2testingfive mice in both the lipopolysaccharide group and the terbutaline groupwere killed at2h,4h and8h, respectively. wet/dry weight ratio of lungwas weighed. TNF-α level in homogenate of lung tissue were tesed byenzyme-linked immunosorbent assay (ELISA). Lung morphologicalchanges was observed by HE. The expression of occludin was measuredby immunohistochemical staining method with computer image analysis.The ultrastructural changes of lung tissue were observed by electronmicroscope. Results: The PaO2of lipopolysaccharide group decreasedsignificantly compared with that of control normal group at4h (P<0.01).The PaO2of each time points in the terbutaline group decreases withcomparison of the lipopolysaccharide group(P<0.01). Compared withnormal control group, wet/dry weight ratio of lung in lipopolysaccharidegroup increased significantly(P<0.01).The wet/dry weight ratio of lung interbutaline group was lower than that in lipopolysaccharide group at eachtime points(P<0.01). The TNF-α level in lung homogenates of thelipopolysaccharide group increased significantly compared with that ofthe normal control group(P<0.01). The TNF-α in lung homogenates ofthe terbutaline group was lower than that of lipopolysaccharide group(P<0.01). The expression level of occludin protein in lung tissue of thelipopolysaccharide group was lower significantly than that of normalcontrol group(P<0.01). The expression level of occludin protein in lung tissue of the terbutaline group was higher than that of lipopolysaccharidegroup at each time points(P<0.01). Electron microscopy showed thealveolar epithelial structure was integrity in the control group and thetight junctions were not damaged. However, damage of the tight junctionsof the alveolar epithelial could be observed in lipopolysaccharide groupand terbutaline group, but terbutaline could alleviate the above changes.Conclusions:(1)The mice models with acute lung injury could besuccessfully induced by intraperitoneal injection of lipopolysaccharide.(2)The destruction of the tight junction of alveolar epithelial cells coulddevelop in the early stage of acute lung injury.(3)Occludin expression ofalveolar epithelial cells was reduced in micee with acute lung injury.(4)Terbutaline could up-regulate occludin expression, which might be one ofthe mechanisms for its promoting restoration of the lung injury.