A Novel Animal Model Of Trauma Brain Injury Accompanied By Seawater Drowning Caused Acute Lung Injury

Part one:the Establishment of Animal Model of Closed and Moderate Traumatic Brain InjuryObject To establish the animal model of closed moderate traumatic brain injury for further study on the related mechanism and treatment tragic research.Methods 80 heatlhy adult male SD rats were divided into sham group(TG0)and group TG1,TG2 and TG3 three different severity of traumatic brain injury(TBI),each group with 20 rats.Free fall acceleration hit device was employed to set up the model of TBI,which was used weight weighted 450 g steel bar falled from the different height(1.0m,1.5m,2m)and hit against the middle of head of rat,caused the three different types of injury levels TG1,TG2 and TG3 respectively.The general conditions,coma duration,neurobehavioral severity score,and pathological changes of brain tissue after TBI were observed post-TBI.Results The death rates of rats with 2 weeks of TG0,TG1,TG2,TG3 group were 0%,5%,20%,60% respectively.With the increased of the TBI severity,the death rates increaseed(P<0.05).Skull fracture incidence of the groups were 0%,0%,5%,0%,respectively.With the increased of the TBI severity,the fracture rates increaseed(P<0.05).The coma duration time post-TBI were(18.13±2.36)min,(38.25±2.92)min,(59.38±3.70)min,(77.88±4.09)min,respectively.With the increased of the TBI severity,the coma duration time become longer(P<0.05).The modifed Neurological Severity Scores(m NSS)of the groups at the time of 1d post-TBI were(1.25±0.46),(3.25±1.04),(5.13±1.13),(7.63±1.41).Then the m NSS score at 3d post-TBI were(1.13±0.35),(2.63±0.74),(3.63±0.92),(5.25±1.04).With the increased of the TBI severity,the m NSS between the TBI group in 1d and 3d post-TBI increased(P<0.05).Compared with the TG0 group,with the increased of the TBI severity,the space around nerve cells and blood vessels became broaden,the arrangement of neurons turned disordered and degenerated,glial cells turned swellen and degenerated much obviously under light microscopic,?-APP andNF-L positive expression level were increased in cerebral cortex according to IHC staining.Conclusions With the height of free fall increased,the TBI severity become more seriously.And the 450g×1.5m have established a relatively stable moderate closed TBI with obviously pathological features changes and more stable than other groups.Part two:the Establishment of Animal Model of Acute Lung Injury Caused by Seawater DrowningObject To provide a platform for the study of SWD-ALI by establish a rat model of acute lung injury caused by seawater drowning(SWD-ALI).Methods Totally 40 male Sprague-Dawley rats were randomly divided into 4 groups,SG0(sham-operated group),SG1 group,SG2 and SG3 group,each group with 10 rats.The seawater drowning model was produced according to the dosage seawater water(1 ml/kg,2 ml/kg,3 ml/kg)pumped into the rat lungs via the trachea in 3 to 5 min at a steady speed using an infusion pump.Arterial blood gases and general situation were observed,HE was used to observe the pathological changes of lung tissue,and in order to quantify the magnitude of pulmonary edema,also the water content of lung was measured after seawater pumped.We judged the indicators of each group to determine whether adopted to the criteria of diagnosis of ALI.Results Compared with the SG0 group,tachypnea,airway with pink foam exudate,cyanosis and wet rales appeared in the rats of seawater drowning groups immediately after perfusion of seawater.Pa CO2 in seawater drowning groups were increased firstly and then decreased,and the 30 min value was the highest,then decreased gradually and stayed lower than the SG0.Pa O2 and Pa O2/Fi O2 increased began at 10 min,then increased gradually,but still kept under than in SG0.The Pa O2/Fi O2 of SG3 group became lower than 300 mm Hg lasting over 120 min postseawater drowning.The the water content of lung samples in SG3 group was significantly higher than the other group.Compared with the SG0 group,pulmonary interstitial edema,alveolar septum fracture,red blood cells enriched in alveolar and inflammatory cells infiltration under light microscope in the pathologic changes of rat lung of seawater drowning groups.The higher the dosage of seawater instilled,the wores serious the pathological changes of lung tissue happened.Conclusion The acute lung injury induced by seawater drowning can be successfully established according to the method that seawater water(3 ml/kg)was instilled into the rat lungs via the trachea at a steady speed using a infusion pump.Part three:A Novel Animal Model of Closed and Moderate Trauma Brain Injury Accompanied by Seawater Drowning Caused Acute Lung InjuryObject To establish a rat model of closed moderate TBI+SWD-ALI and provide a platform for further research on the mechanism,pathophysiology and treatment of the animal model.Methods Totally 80 male Sprague-Dawley rats were randomly divided into 4 groups using a random number table,TBI group(group T),ALI group(group S),TBI+SWD-ALI group(group C),sham-operated group(group N).The general condition,coma duration time,neurobehavioral scores,arterial blood gases,the water content of lung and pathological changes of brain tissue and lung tissue were observed post truma.Results Compared with sham-operated group(group N),TBI(group T)in rats after injury suffered respiratory depression and consciousness change and ALI group(group S)rats after instilling seawater instantly tachypnea,oral cyanosis,foamy liquid was exhaled on bilateral nostrils,Moist crackles could be audible on the both lung areas.The coma duration in TBI+SWD-ALI group(group C)was longer than in the group T(P<0.05).The mortality rates of rats in group T,S,C and N were 25%,10%,40% and 0% respectively,the differences within groups has statistical significance(P<0.05).Pa O2 and Pa O2/Fi O2 showed a trend of rising in group T,S,C 10 min post-injury,then gradually increase towards to normal but still kept low than group N.Pa O2 in group C was lower than that in group S and T at the moment of 10 min post-injury(P<0.05).The lasting time of Pa O2/Fi O2 in group C under 300 mm Hg is over than 120 min,and kept significantly lower than the group S 240 min post-injure(P<0.05).The water content of lung tissue between groups has statistical significance(P<0.05),among them,group C was significantly higher than group N and T(P<0.05).Compared with the group N,1 d,3 d after injury m NSS,group C and group T have statistically significant(P<0.05).Group C compared with group T,1d,3d after injury significant difference between thegroups(P<0.05).Compared with the pathological changes in lung tissue group N,alveolar septa,alveolar interval wide fracture,alveolar space fusion,inflammatory cells infiltration were observed in group S and C acorrding to HE staining.While the space around nerve cells and blood vessels became broaden,the arrangement of neurons turned disordered and degenerated much obviously under light microscopic were observed in group T and C in brain tissues.Both ?-APP and NF-L positive expression can be found after IHC staining.Conclusion The stable animal model of closed moderate TBI+SWD-ALI can be produced based on the model of closed moderate TBI with 450 g ×1.5m,then pump the seawater(3 ml/kg)into the trachea caused ALI at a steady speed using a infusion pump.