Apoptotic pathway in the rat small intestinal mucosa is different between physiological conditions and ischemia-reperfusion

我们先前已经证明，禁食和缺血再灌注（I/R）诱导大鼠肠粘膜细胞凋亡。细胞凋亡主要通过两种途径诱导。本研究旨在比较生理条件（包括禁食和I/R）后的凋亡途径。将大鼠分为两组：I/R组，夹闭肠系膜上级动脉60 min，再灌注60 min;禁食组，禁食24 h或48 h。将其他大鼠的几种生理物质注入脑室。肠细胞凋亡通过电泳和TUNEL测定评估为DNA片段化%。通过Western blot分析评估凋亡蛋白，包括死亡配体/受体、半胱天冬酶。评估小肠粘膜高度和线粒体脱氢酶功能。生理操作和I/R可显著诱导小肠细胞凋亡。禁食大鼠的粘液腺高度显著降低，线粒体功能障碍仅由I/R诱导。Fas、FasL和TNFR 1在两组大鼠的表达均增强。I/R后细胞色素c和切割型caspase-9表达显著增加。相反，在生理条件下，裂解的caspase-8和裂解的caspase-3的表达增加。生理条件通过受体介导的I型凋亡途径促进大鼠小肠粘膜细胞凋亡，I/R通过受体介导的II型凋亡途径诱导大鼠小肠粘膜细胞凋亡。

We have previously demonstrated that fasting and ischemia-reperfusion (I/R) induced apoptosis in rat intestinal mucosa. It is widely accepted that apoptosis is induced through two main pathways. This study aimed to compare apoptotic pathways following physiological conditions including fasting and I/R. Rats were divided into two groups: the I/R group involved occlusion of the superior mesenteric artery for 60 min, followed by 60 min reperfusion; while the fasting group involved fasting for 24 or 48 h. Additional rats were infused several physiological substances into the cerebro-ventricle. Intestinal apoptosis was assessed as% fragmented DNA, by electrophoresis, and by a TUNEL assay. Apoptotic proteins including death ligands/receptors, caspases were evaluated by Western blot analysis. Small intestinal mucosal height and mitochondrial dehydrogenase function were assessed. Physiological manipulation and I/R significantly induced intestinal apoptosis. Mucosal height was significantly decreased in fasting rats, and mitochondrial dysfunction was induced only by I/R. Expressions of Fas, FasL and TNFR1 were enhanced in rats of both groups. After I/R, expressions of cytochrome c and cleaved caspase-9 were significantly increased. In contrast, expressions of cleaved caspase-8 and cleaved caspase-3 increased in the physiological conditions. Physiological conditions promoted mucosal apoptosis via receptor-mediated type I apoptotic pathway in the rat small intestine, and I/R induced apoptosis via mitochondria-mediated type II pathway.