葡萄糖调节蛋白78在大鼠肠缺血再灌注损伤中的表达及其意义

Expression and significance of glucose regulated protein 78 kD in rats with intestine ischemia-reperfusion injury

摘要:

目的：观察大鼠肠缺血再灌注损伤（intestine ischemia reperfusion injury，IIRI）过程中肠黏膜的组织损伤和细胞凋亡及内质网（endoplasmic reticulum，ER）分子伴侣葡萄糖调节蛋白78（glucose regulated protein 78 kD，GRP78）的表达变化，并探讨ER应激在肠IIRI中的作用及机制。方法：45只雄性SD大鼠随机分成9组：缺血再灌注0、1、3、6、12、24、48、72 h组，以及假手术对照组，每组5只。实验组均用无创性动脉夹夹闭肠系膜上动脉1 h后实施再灌注来建立再灌注模型，假手术组仅游离肠系膜上动脉，不夹闭。然后采用HE染色观察肠黏膜变化，TUNEL法检测细胞凋亡，Western blot和RT-PCR检测GRP78表达。结果：缺血再灌注后，肠黏膜损伤程度及细胞凋亡指数随再灌注时间延长而增加，于再灌注3 h达峰值（与其他组各组比较均P<0.001）；再灌注后，GRP78的表达明显增加，于1 h达第1个小高峰（与0 h组和3 h组比较P<0.05），但随再灌注时间的延长，表达量逐步减少，再灌注12 h后开始回升（与6 h组比较P<0.004），于24 h达峰值（与其他各组比较均P<0.05），72 h降至对照组水平（与假手术对照组比较P >0.069）。结论：GRP78在大鼠肠缺血再灌注过程中表达变化，可能与其对肠IIRI保护机制有关。

Abstract:

Objective：To observe the intestinal tissue injury，epithelial cell apoptosis and changes of glucose regulated protein 78 kD （GRP78） expression in the intestine ischemia-reperfusion rats and to investigate the possible effect and mechanism of endoplasmic reticulum stress in the ischemic process. Methods：Forty-five SD rats were randomly divided into 9 groups：sham control group and 0，1，3，6，12，24，48，72 h groups after ischemia reperfusion（n=5）. An experimental model of intestinal ischemia-reperfusion in rats was established by the occlusion of superior mesenteric artery for 1 h by small atraumatic clip and sham control animals were prepared in the same way without the occlusion of superior mesenteric artery. Intestinal tissue injury severity was tested by HE assay，apoptosis of epithelial cells was measured by TUNEL method and expression of GRP78 in intestinal tissue was detected by Western blot and RT-PCR. Results：HE assay and TUNEL showed that the tissue injury and apoptotic index of intestinal mucosa were gradually elevated with the increasing of reperfusion time and reached a peak at 3 h（P<0.01 compared with those in the other groups）. Expression of GRP78 was increased after the reperfusion，reached a first small peak at 1 h（P<0.05 compared with those in 0 h and 3 h groups），but dropped down with the prolonging of reperfusion time，rose again at 12 h（P<0.004 compared with those in 6 h group），reached the peak again at 24 h（P<0.05 compared with those in the other groups） and fell to the level of control group（P>0.069 compared with those in control group）. Conclusion：Changes of GRP78 expression might be associated with the endogenous protective mechanisms.