The Therapeutic Effects Of Ambroxol And Dexamethasone On Acute Lung Injury Induced By Seawater Aspiration In Rats

Objective:1.To study whether ambroxol and?or?dexamethasone can improve the hypoxia status and pulmonary edema in lung tissue,and whether the combined use of the two has synergistic effects;2.To research whether ambroxol and?or?dexamethasone can reduce the oxidation reaction by regulating SOD,MDA and MPO,and whether there can be synergistic effects between two drugs;3.To discuss whether ambroxol and?or?dexamethasone can participate in the regulation of lung apoptosis,and whether the combined use of both early and late has synergistic effects.Methods:A total of 40 Sprague-Dawley healthy male rats were randomly assigned into 5 groups according to the random number table: control group?C group,n=8?,seawater drowning group?M group,n=8?,ambroxol treatment group?A group,n=8?,dexamethasone treatment group?D group,n=8?,ambroxol and dexamethasone treatment group?A+D group,n=8?.In addition to the control group which underwent tracheotomy and endotracheal intubations only,the seawater drowning rat model was reproduced by instilling artificial seawater?4m1/kg body weight?into the tracheal catheter of animals.Ambroxol,ambroxol and dexamethasone treatment group were both received intraperitoneal injection of ambroxol 70mg/kg 30 min before the model had been established,while the dexamethasone,ambroxol and dexamethasone treatment group were given intraperitoneal injection of dexamethasone 5mg/kg immediately after seawater drowning.Blood gas analysis was done at the different time points?30,60,120,240 min after infusion?in the experiment.The rats were killed after 240 min after seawater aspiration and the upper lobe of the left lung was weighed immediately as wet weight,then it was as dry weight when it hasn't changed any more,and the W/D was calculated,the changes of lung wet to dry weight ratio were accumulated and the pathological changes in pulmonary tissue were observed after the experiment.The activity of SOD was determined by xanthine oxidase method?hydroxylamine method?,while and the activity of MPO was measured by the colorimetric method,the content of MDA was used thiobarbituric acid method by respective kits;The Western Blot was used to detect the protein level of Bax,Bcl-2,caspase-3 and cleaved caspase-3.Results:1.Blood gas: The levels of PaCO₂ and PaO₂ decreased at the time point of 30 min after infusion in the seawater aspiration groups compared to C group?P<0.05?,while the M group decreased most obviously;the level of PaO₂ of treatment group was higher than that of M group gradually after 60 min and the PaCO₂ increased rapidly in seawater drowning group?P<0.05?.The level of PaO₂ of arterial blood gas in the treatment group was obviously improved than that of model group after 240min?P<0.05?.2.W/D contrast: The M group was the highest,and A,D,A+D group of lung W/D were statistically different from the M group?P<0.05?,while W/D of the A+D group was lower than that of the A and D group?P<0.05?,and there were no statistically significant difference among the group A and group D?P >0.05?.3.The activity of SOD,MPO and the content of MDA: Determination found that the activity of SOD in the seawater aspiration groups were lower than the C group?P<0.05?,and the A+D group declined less than that of the A and D group?P<0.05?,while the activity of MPO and the content of MDA in the lung tissue of A,D,A+D group was obviously higher than that of C group?P<0.05?,and the M group increased most sharply,group A+D less obviously?P<0.05?.The difference between the A and D group were no statistically significant?P<0.05?and the rest were yes?P>0.05?.4.Western Blot: The results of Western Blot shows that the expression of Bax and cleaved caspase-3/caspase-3 at the protein level in the M group was significantly higher than that in C group?P<0.05?and treatment groups were comparatively less than that of the M group at the time point of 240 min after infusion?P<0.05?,of which the sharpest reduction is group M compared with group C of the level of Bcl-2?P<0.05?.5.HE staining of lung tissue under the light microscope: The lung tissue was complete,and there was no edema,hemorrhage and inflammatory cells infiltration in the alveolar cavity and pulmonary interstitial,and the thickness of the alveolar walls is normal in the C group.The lung tissue was disorder,and there were a large number of red blood cells exudation,neutrophil infiltration in the alveolar cavity and pulmonary interstitial,blood capillaries were dilated,and thicken of alveolar walls can be observed in the seawater drowning group,while those changes were significantly relieved in the A,D,A+D group,and the lung injury change of A+D group was the lightest.Conclusion:1.The levels of PaCO₂ and PaO₂,W/D and the HE stain were various according to different treatments,reminding that ambroxol and?or?dexamethasone can improve the hypoxic status of the lung tissue,and reduce the degree of pulmonary edema,and ultimately achieve the therapeutic effect,and the two may have a synergistic effect.2.The activity of SOD and MPO,the content of MDA in the lung tissue changed correspondingly in rats with acute lung injury induced by seawater aspiration,reminding that SOD,MPO and MDA may involve in the process of SWD-ALI.The lung injury degree has significantly improved after the intervention of ambroxol and?or?dexamethasone,which hints that ambroxol and?or?dexamethasone may reduce oxidative reaction by adjusting the expression of SOD,MPO and MDA,so as to reduce the lung injury and improve oxygenation.3.The expression of Bax,Bcl-2 and cleaved caspase-3/caspase-3 at the protein level has significantly altered at the time point of 240 min after infusion,suggesting the expression of Bax,Bcl-2 and cleaved caspase-3/caspase-3 might be participated in the pathophysiological course of SWD-ALI.Ambroxol and?or?dexamethasone can change the process of Bax,Bcl-2 and cleaved caspase-3/caspase-3,which is likely to be one of the effective mechanisms of lung protection by the ambroxol and dexamethasone in SWD-ALI.