The Effects Of Oxidative Stress On The Apoptosis And Apoptotic-related Gene Expression Of Enterocytes After Severe Burn With Delayed Resuscitation In Rats At Plateau

Objective To evaluate intestinal barrier injury and its mechanism after severe burn with oxidative stress and delayed fluid resuscitation in rats at plateau.Methods A total of 132 Wistar rats were employed as the experimental models,and randomly divided into two groups:Lanzhou group(altitude:1517m) consisted of immediate fluid resuscitation group(LIFR),delayed fluid resuscitation group(LDFR) and control group(LCG).The rats were subjected to 30%TBSA burn burn on the back and served with saline resuscitation immediately or 6h later as delayed resuscitation.The high altitude group(altitude:3840m) was divided as same as the Lanzhou group,they were HIFR,HDFR and HCG groups.The oxidative stress of enterocytes was observed by malonaldehyde(MDA) and total hydrosulfide(TSH) determination;the apoptosis of enterocytes was estimated by TUNEL methods and the expression of bax and bcl-2.HIF-1αwere observed by SP method.Pathological technique,tissue microarry,immunohistochemistry,image analysis techniques were employed to detect pathological changes of intestine,MDA and TSH,apoptosis, protein expressions of bax,bcl-2,HIF-1αand their relationship were estimated.Results1.With altitude risied,intestinal mucosa thickness increased strikingly,Intestinal structure swelled and disordered,apoptotic bodies and Intestinal vacuole-like structure increasied appeared in intestinal tissue,and inflammatory cells.The significant differences appeared between DFR and IFR,especailly between HDFR and LDFR.2.The changes of the contents of intestinal malonaldehyde(MDA) and total hydrosulfide(TSH) were determined to observe the oxidative stress of enterocytes after burn.The levels of MDA on plateau compared with that in Lanzhou were changed largely and discerned levels on plateau much higher in DFR and IFR than those in Lanzhou.The levels of TSH paralleled the revers of the levels of MDA.3.A positive expression of bax,bcl-2,HIF-1αappeared in nucleus and cytoplasmic. The expression level of bax,HIF-1αwere much higher in DFR and IFR than those in CG,at 3840m altitude than those at 1517m,and in DFR than those in IFR(P＜0.05) bcl-2 gene was not detected in high altitude groups or 6h,12h postburn in lanzhou groups;A weak expression of bcl-2 was discerned at other time point in Lanzhou groups.4.The expression level of apoptosis was much higher in DFR and IFR than those in CG,at 3840m altitude than those at 1517m,and in DFR than those in IFR(P＜0.05).5.A positive relationship existed between the levels of MDA and the change of bax (HDFR,r=0.938,P＜0.05),and apoptotic cells(HDFR,r=0.899,P＜0.05).A negative relationship existed between the levels of TSH and the change of bax(HDFR, r=-0.934,P＜0.05),and apoptotic celIs(HDFR,r=-0.948,P＜0.05).Conclusion1.With altitude height rising,there were obviously differences of pathological changes of intestinal tissue after severe burn with delayed fluid resuscitation and oxidative stress.2.Oxidative stress was an important factor of intestinal barrier injury after severe burn with delayed fluid resuscitation in rats at plateau.3.The changes of bax and bcl-2 expression were one of the important mechanisms of apoptosis in intestine injury after severe burn with delayed fluid resuscitation in rats at different altitude. 4.HIF-1αexpression was closely related with intestinal epithelial cell apoptosis in rats after severe burns with with delayed fluid resuscitation at different altitude.5.Intestinal tissue apoptosis cell number was increased after severe burn with delayed fluid resuscitation at high altitude.