The role of ischemic preconditioning in the expression of apoptosis-related genes in a rat model of intestinal ischemia-reperfusion injury

Abstract Purpose: To analyze the effects of ischemic preconditioning (IPC) in the expression of apoptosis-related genes in rat small intestine subjected to ischemia and reperfusion. Methods: Thirty anesthetized rats underwent laparotomy and were drive into five groups: control (CG); ischemia (IG); ischemia and reperfusion (IRG); IPC and ischemia (IG+IPC); IPC and ischemia and reperfusion (I/RG+IPC). Intestinal ischemia was performed by clamping the superior mesenteric artery for 60 minutes, whereas reperfusion lasted for 120 minutes. IPC was carried out by one cycle of 5 minutes of ischemia followed by 10 minutes of reperfusion prior to the prolonged 60-minutes-ischemia and 120-minutes-reperfusion. Thereafter, the rats were euthanized and samples of small intestine were processed for histology and gene expression. Results: Histology of myenteric plexus showed a higher presence of neurons presenting pyknotic nuclei and condensed chromatin in the IG and IRG. IG+IPC and I/RG+IPC groups exhibited neurons with preserved volume and nuclei, along with significant up-regulation of the anti-apoptotic protein Bcl2l1 and down-regulation of pro-apoptotic genes. Moreover, Bax/Bcl2 ratio was lower in the groups subjected to IPC, indicating a protective effect of IPC against apoptosis. Conclusion: Ischemic preconditioning protect rat small intestine against ischemia/reperfusion injury, reducing morphologic lesions and apoptosis.

摘要
研究目的：分析缺血预处理（ischemic preconditioning, IPC）对缺血再灌注（ischemia and reperfusion）损伤大鼠小肠凋亡相关基因（apoptosis-related genes）表达的影响。
研究方法：将30只麻醉大鼠实施剖腹手术，随机分为5组：对照组（CG）、缺血组（IG）、缺血再灌注组（IRG）、缺血预处理+缺血组（IG+IPC）以及缺血预处理+缺血再灌注组（I/RG+IPC）。肠道缺血模型通过夹闭肠系膜上动脉（superior mesenteric artery）60分钟构建，再灌注持续时长为120分钟。缺血预处理方案为：在长时间缺血（60分钟）与再灌注（120分钟）前，先实施1次缺血5分钟、再灌注10分钟的循环。随后处死大鼠，采集小肠样本用于组织学（histology）检测与基因表达分析。
研究结果：肌间神经丛（myenteric plexus）组织学检测显示，缺血组（IG）与缺血再灌注组（IRG）中，存在固缩核（pyknotic nuclei）与染色质固缩（condensed chromatin）的神经元数量显著增多。缺血预处理+缺血组（IG+IPC）与缺血预处理+缺血再灌注组（I/RG+IPC）的神经元体积与细胞核形态均保持完整，同时抗凋亡蛋白Bcl2l1的表达显著上调，促凋亡基因（pro-apoptotic genes）表达则显著下调。此外，接受缺血预处理的各组Bax/Bcl2比值（Bax/Bcl2 ratio）更低，表明缺血预处理对细胞凋亡具有保护作用。
研究结论：缺血预处理可通过减轻形态学损伤与细胞凋亡，对缺血再灌注损伤大鼠小肠起到保护作用。