Ischemic preconditioning reduces caspase-related intestinal apoptosis.
ABSTRACT To investigate the preventive effect of ischemic preconditioning (IPC) on ischemia/reperfusion (I/R)-induced apoptosis and injury in the rat intestine.
We divided 30 male Wistar rats, weighing 300-350 g, randomly into three groups. The control group rats (n = 10) were subjected to laparotomy only; the I/R group (n = 10) rats were subjected to occlusion of the superior mesenteric artery for 45 min, followed by reperfusion for 60 min; and the IPC group (n = 10) rats were subjected to IPC, achieved with two cycles of 5 min ischemia and 5 min reperfusion immediately before the I/R, as in the I/R group. Blood samples were collected by cardiac puncture, to measure nitrate and myeloperoxidase (MPO) levels. Histopathological and immunohistochemical studies were done to evaluate the I/R-induced apoptosis and injury.
The blood MPO and nitrate levels were increased in the I/R group, but IPC prevented their increase. There were significantly fewer apoptotic cells in the IPC group than in the I/R group, and this finding was supported by the caspase-3 expression in the ileum. The intestinal histopathology was also protected by IPC against I/R-induced injury.
Ischemic preconditioning clearly prevented I/R-induced injury and apoptosis by a mechanism related to the caspase-3-dependent pathway. We also showed that IPC inhibited leukocyte activation, with the suppression of myeloperoxidase levels in I/R and nitric oxide-related oxidoinflammatory pathway upregulation.
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ABSTRACT: To develop an in vivo intestinal permeability assay applying magnetic resonance imaging (MRI) to monitor real-time gut barrier defects in animal models of acute mesenteric ischemia/reperfusion (I/R) insult. Twenty Wistar rats were divided to 2 groups for I/R challenge or sham controls. I/R rats received occlusion of superior mesenteric artery for 20 minutes and reperfusion for 1 hour. Sham-operation controls received laparotomy without manipulation of artery. To assess gut permeability, a 10-cm jejunal sac was created distal to the ligament of Treitz in both groups of rats after laparotomy, and a contrast agent (gadodiamide) was injected into the lumen of the ligated intestinal sac. The signals produced by gadodamide in the liver, kidney, and plasma before and after the start of reperfusion were examined by 1.5 Tesla MRI (GE Signa Excite), and the increment of signal-to-noise ratio (SNR) in these organs that parallels the luminal-to-serosal flux rate of the probe was used as an indicator of gut permeability. At the end of procedures, jejunal tissues and mucosal scrapings were collected for histologic examination and Western blotting for epithelial tight junctional proteins. Moreover, liver and spleen homogenates were cultured on fresh blood agar plates to measure the bacterial colony-forming units per gram of tissue. In I/R rats, disrupted villous structure and decreased epithelial tight junctional expression were seen in the jejunum associated with massive enteric bacterial translocation to the liver and spleen. The SNR in the liver of I/R rats was higher than sham controls (2.65 +/- 0.56 vs. 0.65 +/- 0.26, P < 0.01) at 15 minutes postreperfusion. Elevation of SNR in the kidney was also found in I/R rats compared with sham controls (11.61 +/- 2.07 vs. 3.06 +/- 1.15, P < 0.05). The plasma gadodiamide concentration in I/R rats was significantly increased compared with sham controls (0.220 +/- 0.044 vs. 0.006 +/- 0.004 mM, P < 0.01) at 15 minutes postreperfusion. This novel MRI-based intestinal permeability assay has shown a significant increase in the signal intensity in liver, kidney, and plasma samples that correlated with mucosal barrier defects in experimental models of acute mesenteric I/R.Investigative radiology 04/2009; 44(6):329-35. · 4.85 Impact Factor
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ABSTRACT: Ischemic-reperfusion (IR) injury of the small intestine makes a serious complications associated with various surgical procedures and is related to changes in motility, secretory activity and structural alterations. Preconditioning can reduce range of this damage. The aim of the experimental study was to determine the influence of ischemic preconditioning (IPC) on IR injury on jejunal epithelial layer. Wistar rats (n = 56) were divided in two experimental groups. IR group was subjected to 60 min ischemia of cranial mesenteric artery and followed by reperfusion periods: 1,4,8,24 h (IR1, IR4, IR8, IR24). Group with ischemic preconditioning (IPC+IR) was subjected to two subsequent ischemic attacks (12 min) with 10 min of reperfusion between them, and after 2nd attack ischemia was induced for 60 min followed by relevant reperfusion period. IPC showed the protective impact on the jejunal tissue architecture after 1 h reperfusion, when in IR1 group the highest and significant damage was observed (p < 0.001) in contrast to IPC+IR1 group. Histopathological damage of the intestine in pretreated groups was postponed to 4 h of reperfusion. Protective effect of IPC together with later accumulation of injury signs were confirmed by weaker impact on goblet cell (p < 0.001) and Paneth cell populations (p < 0.05).The increased cells proliferation in preconditioned groups came later, but stronger after 8 h of reperfusion (p < 0.001) and after 24 h of reperfusion still remained at the high activity level (p < 0.001). Our experimental results on the histopathological changes in the jejunum during ischemic preconditioning proved that IPC may have a positive effect on maintaining intestinal barrier function.Journal of molecular histology 02/2012; 43(2):171-8. · 1.75 Impact Factor
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ABSTRACT: Intestinal ischemia/reperfusion (IR) injury involves activation of inflammatory mediators, mucosal necrosis, ileus, and alteration in a variety of gene products. Ischemic preconditioning (IPC) reduced all the effects of intestinal injury seen in IR. In an effort to investigate the molecular mechanisms responsible for the protective effects afforded by IPC, we sought to characterize the global gene expression pattern in rats subjected to IPC in the setting of IR injury. Rats were randomized into five groups: (1) Sham, (2) IPC only (3) IR, (4) Early IPC + IR (IPC --> IR), and (5) Late IPC + IR (IPC --> 24 h --> IR). At 6 h after reperfusion, ileum was harvested for total RNA isolation, pooled, and analyzed on complementary DNA (cDNA) microarrays with validation using real-time polymerase chain reaction (PCR). Significance Analysis of Microarray (SAM) software was used to determine statistically significant changes in gene expression. Early IPC + IR had 5,167 induced and 4 repressed genes compared with the other groups. SAM analysis revealed 474 out of 10,000 genes differentially expressed among the groups. Early and Late IPC + IR had more genes involved in redox hemostasis, the immune/inflammatory response, and apoptosis than either the IPC only or IR alone groups. The transcriptional profile suggests that IPC exerts its protective effects by regulating the gene response to injury in the intestine.Digestive Diseases and Sciences 09/2009; 55(7):1866-77. · 2.26 Impact Factor