热休克预处理对严重烫伤大鼠胃黏膜氧自由基的作用

目的:观察热休克预处理对严重烫伤大鼠胃黏膜氧自由基及热休克蛋白(HSP)70表达的影响,探讨氧自由基在大鼠烫伤后急性胃黏膜损伤中的作用及热休克预处理对严重烫伤大鼠胃黏膜的保护作用机制。方法:将96只Wistar大鼠随机分为烫伤组(B组,n=48,其中8只大鼠作为正常对照)及热休克预处理后烫伤组(HB组,n=48,其中8只大鼠作为实验对照),观察各时相点两组大鼠胃黏膜损伤指数(UI)、胃黏膜丙二醛(MDA)及胃黏膜细胞SOD活性变化。应用免疫组化染色分析胃黏膜细胞中HSP 70表达变化。结果:大鼠严重烫伤后胃黏膜细胞SOD大量消耗,MDA显著增加,胃黏膜损害明显;热休克预处理能显著减轻大鼠严重烫伤后急性胃黏膜损害。HB组较B组大鼠胃黏膜HSP 70表达水平显著升高(P<0.05),热休克预处理能显著降低胃黏膜细胞SOD的消耗,减少MDA的产生。胃黏膜损伤指数(UI)与MDA呈显著正相关(r=0.695,P<0.01),与HSP 70呈显著负相关(r=-0.794,P<0.01);胃黏膜SOD与MDA呈显著负相关(r=-0.823,P<0.01),而与HSP 70呈显著正相关(r=0.527,P<0.05)。结论:严重烫伤大鼠胃黏膜存在氧自由基损伤;热休克预处理可显著减轻烫伤大鼠胃黏膜氧自由基损伤,保护机制与HSP 70保护抗氧化酶SOD活性密切相关。

Effects of Heat Shock Preconditioning on Oxygen Free Radical in Gastric Mucosa of Burned Rats

Objective:To observe the influence of heat shock preconditioning on oxygen free radical(OFR) and the expression of heat shock protein(HSP)70 in gastric mucosa of severely burned rats in order to investigate its protective mechanism on burn-induced acute gastric mucosal lesion.Methods:Ninety-six Wistar rats were divided into two groups: burn(B) and heat shock preconditioning before burn(HB).The rats in two groups were sacrificed and laparotomized at each time point.The extent of gastric mucosal lesions(UI) was evaluated.The superoxide dismutase(SOD) and malondialdegyde(MDA) levels in gastric mucosa of burned rats were also determined.Immunohistochemical method was used to analyze the expression of HSP 70.Results: After burn injury,the activity of superoxide dismutase(SOD) decreased and the production of MDA obviously increased in rat gastric mucosa as the time elapses.The rats in B group were induced conspicuous gastric mucosal lesions,while UI in HB group was significantly lower.The expression of HSP 70 was significantly increased in HB group compared with those in B group.Heat shock preconditioning could reduce the massive consumption of SOD and production of MDA obviously increased in gastric mucosa.A positive correlation was shown between UI and MDA(r=0.695,P<0.01),between SOD and HSP 70(r=0.527,P<0.05).A negative correlation existed between SOD and MDA(r=-0.823,r=-0.794,P<0.01).Conclusion:These results suggested that there exists OFR injury in gastric mucosa of burned rats.Heat shock preconditioning could ameliorate OFR injury in burned rats.The protective machanisms are related to the protection of superoxide dismutase by HSP 70.