全身热应激预处理对大鼠肠缺血—再灌注损伤程度的影响及机制

Effect of different temperature previous heat stress treatment on intestinal injury following mesenteric ischemia/reperfusion in rats

目的观察全身热应激预处理对大鼠肠缺血—再灌注损伤(IR)程度的影响及其机制。方法 50只SD大鼠随机分为5组,各10只。A组为正常体温+假手术对照组,B组为正常体温+肠IR组;C组为38.5～39℃热应激+肠IR组,D组为40～40.5℃热应激+肠IR组,E组为41.5～42℃热应激+肠IR组。自然恢复血液灌注后60 min,取大鼠肠组织行形态学观察,取肠黏膜组织用Western blot法检测肠黏膜热休克蛋白(HSP)72表达,用原位末端缺口标记法(TUNEL)检测大鼠肠黏膜上皮细胞凋亡情况,用比色法检测肠黏膜Caspase-3活性。结果光镜下观察B组见有固有层破坏,出血;C组损伤程度比B组轻,见部分绒毛顶端破损;D、E组肠黏膜损伤程度更轻,仅出现绒毛顶端上皮下间隙增大或绒毛轻度水肿。肠黏膜HSP72水平A、B、C、D、E组分别为0.40±0.09、0.26±0.09、1.08±0.11、1.39±0.23、2.72±0.88。C、D、E组肠黏膜组织HSP72蛋白水平明显高于A、B组(P均<0.05);E组肠黏膜组织HSP72蛋白水平明显高于C、D组(P均<0.05)。A、B、C、D、E组大鼠肠黏膜组织细胞凋亡率分别为4.60%±1.12%、35.53%±3.40%、21.10%±3.11%、7.50%±1.88%、6.60%±1.83%。肠黏膜细胞凋亡率D、E组比B组降低(P均<0.05)。A、B、C、D、E组大鼠肠黏膜组织Caspase-3活性分别为1.22±0.14、2.72±0.55、1.33±0.24、1.41±0.30、1.16±0.30,C、D、E组大鼠肠黏膜组织Caspase-3活性与B组相比明显降低(P均<0.05)。结论全身热应激预处理对肠IR有保护作用,以40、42℃热应激预处理保护作用较强,其机制与HSP72的表达水平有关。

Objective To investigate the effect of intensity previous heat stress treatment on intestinal injury rats fol- lowing mesenteric ischemia/reperfusion （I/R）. Methods There were 50 adult, male Sprague-Dawley rats divided into 5 groups equelly. Group A was control group（CTRL）. Group B was ischemia/reperfusion group （IR）. Group C was 38.5℃ to 39℃ previous heat stress treatment and then ischemia reperfusion group（39IR）. Group D was 40℃ to 40.5℃ previous heat stress treatment and then ischemia repeffusion group（40IR） . Group E was 41.5 % to 42 ℃ previous heat stress treatment and then ischemia reperfusion gronp（42IR）. The expression of HSP72 was examined in the small intestinal muco- sa by using Western blot. The apoptosis of intestinal mucosal epithelial cell was examined by using terminal deoxylnucleoti- dy-1 transferase mediated-dUTP nick end labeling（TUNEL）. The enzymatic activity of Casapse-3 in mucosal cell was as- sayed by using colorimetric. Results The expression of HSP72 protein increased linearly as previous heat stress treatment temperature. The enzymatic activity of Caspase-3 decreased obviously in C, D, E group and significantly difference than group B （ P 〈 0.05 ）. The number of mucosal epithelia ceils that underwent apoptosis decreased obviously in group D, E than group B. There was not a significant difference between group B and C. Moreover, There was not a significant differ- ence in the enzymatic activity of Caspase-3, the number of apoptosis mucosal epithelial ceils between group C, E and A. Conclusions Different temperature previous heat stress treatment can protect against subsequent mesenteric ischemia reperfusion injury, especially at 40 ℃ and 42 ℃. The mechanism of this protective effect might be related to the increased expression of HSP72.