The curative effect of cannabinoid 2 receptor agonist on functional failure and disruptive inflammation caused by intestinal ischemia and reperfusion

Ischemia and reperfusion of intestinal tissue (intestinal I/R) induce disruption of ileal contractility and chain responses of inflammatory. The aim of this study was to reveal whether therapeutic value of cannabinoid 2 (CB2) receptor activity in the intestinal I/R, via to the exogenous administration of CB2 agonist (AM-1241). Intestinal I/R injury were performed through 30-min ischemia and 150-min reperfusion of mesenteric artery in Wistar rats. The pre-administered doses of 0.1, 1, and 5 mg/kg of CB2 agonist were studied to inhibit inflammation of intestinal I/R injury including ileum smooth muscle contractility, polymorphonuclear cell migration, oxidant/antioxidant defense system, and provocative cytokines. Pre-administration with CB2 receptor agonist ensured to consider improving the disrupted contractile responses in ileum smooth muscle along with decreased the formation of MDA that production of lipid peroxidation, reversed the depleted glutathione, inhibited the expression of TNF-α and of IL-1β in the intestinal I/R of rats. Taken together results of this research, the agonistic activity of CB2 receptor for healing of intestinal I/R injury is ensuring associated with anti-inflammatory mechanisms such as the inhibiting of migration of inflammatory polymorphonuclear cells that origin of acute and initial responses of inflammation, the inhibiting of production of provocative and pro-inflammatory cytokines like TNF-α and IL-1β, the rebalancing of oxidant/antioxidant redox system disrupted in injury of reperfusion period and the supporting of physiologic defensive systems in endothelial and inducible inflammatory cells.     

Moderate hypothermia protects against systemic oxidative stress in a rat model of intestinal ischemia and reperfusion injury

Multisystem organ failure represents a major cause of mortality in intestinal ischemia and reperfusion (I/R), and oxidative stress plays a key role in its pathogenesis. Hypothermia is beneficial in I/R injury, but its effects on systemic oxidative stress have not been elucidated. The aim of this study was to evaluate the effects of moderate hypothermia on systemic oxidative stress after intestinal I/R injury. Anaesthetized adult rats (n = 10 per group) underwent 60 min of intestinal ischemia followed by 120 min of reperfusion or sham operation at normothermia (36 degrees C-38 degrees C) or moderate hypothermia (30 degrees C-32 degrees C). At sacrifice, ileum, liver, lungs, and kidneys were removed to determine the concentration of malondialdehyde (a marker of lipid peroxidation), reduced and oxidized glutathione (a major endogenous antioxidant), and glutathione redox state. Plasma malondialdehyde and nitrate plus nitrite (reflecting nitric oxide production) were also analyzed. A marked elevation of malondialdehyde was observed after I/R at normothermia in plasma, ileum, and lungs; however, hypothermia during I/R prevented this increase. I/R at normothermia caused a profound decrease in reduced glutathione and glutathione redox state in the ileum, but this was not observed in I/R at hypothermia. Interestingly, hypothermia increased glutathione content of control intestine. Nitric oxide production was increased only in normothermic I/R animals. Moderate hypothermia attenuates systemic oxidative stress associated with experimental intestinal I/R in an animal model by decreasing lipid peroxidation in plasma, ileum, lungs, and kidneys, by preventing the depletion of gut glutathione, and by reducing systemic nitric oxide production. However, whether these effects persist after rewarming is unknown.     

Nitric oxide synthase inhibitors affect nitric oxide synthesis in normoxic but not in ischemic organs during intestinal ischemia and early reperfusion

Inhibition of endogenous nitric oxide (NO) synthesis during early intestinal ischemia/reperfusion (I/R(i)) enhances remote organ damage related to I/R(i). However, the effects of NO synthase (NOS) inhibitors on NO formation in various organs have not yet been specified. We therefore investigated the effects of N-G-monomethyl-L-arginine (L-NMMA), a nonspecific NOS inhibitor, and L-arginine, the NOS substrate, on NO formed in ischemic intestine versus normoxic remote organs (lung and liver). We used electron paramagnetic resonance spectroscopy and a specific NO trap to assay NO in blood, intestine, lung, and liver of rats subjected to local I/R(i), with and without L-NMMA and L-arginine supplementation. We found that I/R(i) increased NO levels in the intestine and blood, but not in the remote organs lung and liver. Administration of L-NMMA before I/R(i) decreased I/R(i)-independent basal NO levels in normoxic lung and liver without influencing I/R(i)-induced increase in NO levels in intestinal tissue or in blood. L-arginine supplementation increased circulating levels of NO, with sensitivity to L-NMMA, without affecting NO levels in normoxic or ischemic tissue. Our data suggest that NOS activity controls the NO generated in normally perfused remote organs during early I/R(i). Hence NOS inhibitors, when administered during I/R(i), decrease physiological NO levels in normoxic remote organs without affecting increased NO levels originating from ischemic intestine. This may explain the harmful effect of nonspecific NOS inhibitors during early I/R(i). In addition, the generation of NO in remote organs is not limited by tissue L-arginine concentrations and, therefore, not influenced by exogenous L-arginine. The protective effect of L-arginine supplementation during I/R(i) is probably related to increasing intravascular NO formation.     

Ischemic preconditioning reduces intestinal epithelial apoptosis in rats

Recent experimental studies have described protective effect of ischemic preconditioning (IPC) on ischemia-reperfusion (I/R) injury of the intestine. We hypothesize that to reach a new point of view on the effect of IPC in intestinal barrier function, the relationship between I/R-induced mucosal injury and apoptosis must first be clarified. The present study was undertaken to investigate the role of IPC on intestinal apoptosis and probable contributions of bcl-2 expression to this process. We also investigated the effect of intestinal IPC on ileal malondyaldihyde levels. Forty-four male Wistar rats were randomized into four groups each consisting of 11 rats: sham-operated control, I/R group (30 min of superior mesenteric artery occlusion), IPC-I/R group (10 min of temporary artery occlusion prior before an ischemic insult of 30 min), and IPC alone group (10 min of preconditioning). Twenty-four hours later, ileum samples were obtained. Ileal malondyaldihyde levels were increased in the I/R group (31.9 +/- 18.8 vs. 106.8 +/- 39.8) but not in the IPC alone and IPC-I/R groups (38.1 +/- 13.6 and 44.7 +/- 12.7; P < 0.01). The number of apoptotic cells was significantly lower in IPC-I/R group than that of I/R group, and these findings were further supported by DNA laddering and M30 findings. Diminished bcl-2 expression observed in the ileal specimens of I/R group was prevented by IPC. Our results indicate that IPC may provide a protective effect on ileal epithelium and that this effect is probably the result of a significant increase in the expression of bcl-2 after the insult. The reversal of apoptosis by IPC might help preserving the vitality of intestinal structures that have a critical function, cessation of which often leads to multiorgan dysfunction syndrome.     

Effects of melatonin and caffeic acid phenethyl ester on testicular injury induced by myocardial ischemia/reperfusion in rats

Experimental studies indicate that ischemia/reperfusion (I/R) causes remote organ injury although the molecular mechanism has not been clearly defined. In this report, the role of oxidative injury on testicular damage following myocardial I/R injury and the effects of antioxidant agents, melatonin and caffeic acid phenethyl ester (CAPE), on testicular injury were investigated. As far as we know, this is the first report demonstrating that myocardial I/R induces damage to the testes. Thirty-two male Wistar rats were randomly divided into four groups: sham operation (SO), I/R + vehicle, I/R + melatonin, and I/R + caffeic acid phenethyl ester. To produce cardiac damage, the left main coronary artery was occluded for 30 min, followed by 120 min reperfusion, in anesthetized rats. Serum nitric oxide (NO) and malondialdehyde (MDA) levels and morphological changes were examined. I/R was accompanied by a significant increase in serum MDA and NO levels, whereas, melatonin and CAPE administration significantly reduced these values. Melatonin was more efficient in reducing MDA levels than CAPE (P < 0.05). I/R induced myocardial damage, manifested as the histopathological evidence of intracellular vacuolization, interstitial edema, neutrophil infiltration and coagulative necrosis. I/R + vehicle group showed many histological alterations such as focal tubular atrophy, and degeneration and disorganization of the seminiferous epithelium in testes. The number of atrophic tubules and degenerating cells was significantly higher in I/R + vehicle group than that of SO group. Melatonin and CAPE significantly reduced the number of degenerating cells; additionally, melatonin reduced the number of atrophic tubules (P < 0.05). Our results indicate that myocardial I/R induces severe testicular damage and antioxidant agents, especially melatonin, have protective effects on testicular injury after myocardial I/R. Our data emphasize that oxygen-based reactants may play a central role in remote organ injury.     

Intestinal ischemic preconditioning protects the intestine and reduces bacterial translocation

Ischemic preconditioning (IPC) was first demonstrated in the heart, but this protective effect has been also recently described in the intestine. The aim of this study was to determine the effects of intestinal ischemic preconditioning on the morphology of intestine and bacterial translocation. Twenty-four male Wistar rats weighting 250 to 300 g were randomized into three groups. A control group of rats (n = 8) were subjected laparotomy. In an ischemic group (n = 8), laparotomy was performed and the superior mesenteric artery was occluded by an atraumatic clamp for 30 min. In the preconditioned group (n = 8), before the ischemia-reperfusion (I/R) period (as in ischemic group), rats were subjected to an initial 10 min of intestinal ischemia and 10 min of reperfusion. Twenty-four hours later, to evaluate whether the I/R induced intestinal injury and bacterial translocation (BT), tissue and blood samples were collected, and liver, spleen, and mesenteric lymph node specimens were obtained under sterile conditions for microbiological analysis. Samples of ileum were removed for both biochemical and histopathological evaluation. In the I/R group, the incidence of bacteria-isolated mesenteric lymph nodes, spleen, liver, and blood was significantly higher than other groups (P < 0.05). IPC prevented I/R-induced BT and it significantly reduced the I/R-induced intestinal injury (P < 0.05). Increased inducible nitric oxide (NO) synthase (iNOS) expression observed on the ileal specimens of the I/R group was found to be prevented by IPC. Our data suggest IPC as a key factor that reduces BT and iNOS activation in intestinal I/R. This is the first study showing that intestinal IPC blocks the cascade of events that causes BT and intestinal injury that may lead to sepsis.     

Pretreatment with bone morphogenetic protein-7 (BMP-7) mimics ischemia preconditioning following intestinal ischemia/reperfusion injury in the intestine and liver

Intestinal ischemia/reperfusion (I/R) injury has been shown to cause intestinal mucosal injury and adversely affect function. Ischemic preconditioning (IPC) has been shown to protect against intestinal I/R injury by reducing polymorphonuclear leukocyte infiltration, intestinal mucosal injury, and liver injury, and preserve intestinal transit. Bone morphogenetic protein 7 (BMP-7) has been shown to protect against I/R injury in the kidney and brain. Recently, microarray analysis has been used to examine the possible IPC candidate pathways. This work revealed that IPC may work through upregulation of BMP-7. The purpose of this study was to examine if pretreatment with BMP-7 would replicate the effects seen with IPC in the intestine and liver after intestinal I/R. Rats were randomized to six groups: sham, I/R (30 min of superior mesenteric artery occlusion and 6 h of R), IPC+R (three cycles of superior mesenteric artery occlusion for 4 min and R for 10 min), IPC+I/R, BMP-7+R (100 microm/kg recombinant human BMP-7), or BMP-7+I/R. A duodenal catheter was placed, and 30 min before sacrifice, fluorescein isothiocyanate-Dextran was injected. At sacrifice, dye concentrations were measured to determine intestinal transit. Ileal mucosal injury was determined by histology and myeloperoxidase activity was used as a marker of polymorphonuclear leukocyte infiltration. Serum levels of aspartate aminotransferase were measured at sacrifice to determine liver injury. Pretreatment with BMP-7 significantly improved intestinal transit and significantly decreased intestinal mucosal injury and serum aspartate aminotransferase levels, comparable to animals undergoing IPC. In conclusion, BMP-7 protected against intestinal I/R-induced intestinal and liver injury. Bone morphogenetic protein 7 may be a more logical surrogate to IPC in the prevention of injury in the setting of intestinal I/R.     

Contribution of nitric oxide to the protective effects of ischemic preconditioning in ischemia-reperfused rat kidneys.

We examined the contribution of nitric oxide (NO) to the effect of ischemic preconditioning (IP) on renal function and the hemodynamics in ischemia-reperfusion (I/R) mediated kidney injury. IP was performed by using 4 minutes of ischemia followed by a 30-minute reperfusion interval. I/R treatment consisted of a 30-minute ischemia and 60-minute reperfusion interval. We measured the glomerular filtration rate (GFR), the fractional excretion of sodium (FE(Na)), and the renal blood flow (RBF) in IP+I/R and I/R kidneys. Rats were pretreated with NaCl, N(G)-nitro-L-arginine methyl ester (L-NAME), or L-arginine. We found that IP significantly improved GFR and FE(Na) as compared with I/R treatment; however, this effect was completely abolished by L-NAME injection and enhanced by L-arginine treatment. L-NAME treatment significantly diminished RBF but did not alter nitrite/nitrate excretion. Furthermore, we found that IP alone does not lead to inducible NO synthase protein expression whereas I/R or IP+I/R treatment clearly did. Moreover, we observed an increased heme oxygenase-1 expression in IP+I/R kidneys as compared with I/R treated ones. Our results clearly showed that IP pretreatment protects kidneys from I/R mediated tissue injury and that these effects were partially mediated by NO.     

The effect of pentoxifylline on intestinal ischemia/reperfusion injury

The small intestine is highly sensitive to oxygen free radical-induced injury. Post-ischemic intestinal tissue damage appears to be due to the formation of oxygen radicals. Free radical initiated lipid peroxidation (LP) following intestinal ischemia/reperfusion (I/R) may disrupt mucosal integrity. Indirectly, the radicals trigger the accumulation of neutrophils within the affected tissue, initiating inflammatory processes that lead to severe mucosal lesions. In the present study we investigated the effect of pentoxifylline (PTX), a potent inhibitor of tumour necrosis factor production, on I/R induced intestinal injury. Wistar albino rats were divided into four groups: (1) Sham operation (S); (2) Sham operation + PTX (50 mg/kg i.v.) (S + PTX); (3) 1 h ischemia + 2 h reperfusion (I/R); and (4) I/R + PTX. Animals were sacrificed at the end of the reperfusion period and ileum samples were obtained. Malondialdehyde (MDA) levels, an end product of LP, glutathione (GSH) levels, a key antioxidant, and myeloperoxidase (MPO) activity (an index of polymorphonuclear neutrophils) stimulation, were determined in ileum homogenates. The results of the present study indicate that ischemia/reperfusion results in a significant increase in MDA content and MPO activity with a significant decrease in GSH content. Treatment with PTX returns these biomarkers to control values. A mechanism of this protective effect may involve inhibition of neutrophil oxidative burst.     

高压氧对大鼠肠缺血-再灌注损伤致细胞凋亡的影响

目的 观察大鼠在小肠缺血-再灌注(I/R)不同时期应用高压氧(HBO)治疗对小肠黏膜细胞凋亡的影响,并探讨其作用机制.方法 采取大鼠肠系膜上动脉(SMA)钳夹缺血60 min,松钳夹再灌注60 min,建立S-D大鼠小肠I/R损伤模型,并随机(随机数字法)分成4组:I/R组、缺血前HBO治疗组或HBO预处理组(HBO-P)、缺血期HBO治疗组(HBO-I)和再灌注期HBO治疗组(HBO-R).再灌注60 min后,取回肠末端小肠标本.采用酶连免疫吸附试验法(Elisa)检测肠道组织TNF-α,用比色法检测肠道组织匀浆含量ATP,用免疫组化法检测小肠组织中半胱氨酸天门冬氨酸特异蛋白酶(Caspase-3)的表达.数据以均数±标准差(-x±s)表示,采用单因素方差分析检验,独立样本间比较采用SNK-q检验.结果 肠道组织TNF-α含量在HBO-I组最低,其次为HBO-P组(每两组比较P＜0.05),但前两组明显低于HBO-R组和I/R组(P＜0.05),HBO-R组略低于I/R组,但差异无统计学意义(P＞0.05);Caspase-3表达在HBO-I组最低,HBO-P组次之(两组比较P＜0.05);HBO-R和I/R组最高(与前两组比较P＜0.05),尽管HBO-R组略低于I/R组,但差异无统计学意义(P＞0.05);ATP含量在HBO-I组最低,HBO-P组次之(两组比较P＜0.05),HBO-R和I/R组最高(与前两组比较P＜0.05),尽管HBO-R组略低于I/R组,但差异无统计学意义(P＞0.05).结论 HBO、小肠I/R损伤和小肠黏膜上皮凋亡之间存在联系;HBO治疗可以维持黏膜上皮细胞能量代谢,减少ATP耗竭,降低肠道组织TNF-α含量,减轻I/R损伤小肠黏膜上皮凋亡;在缺血期和缺血前应用HBO治疗显示有益结果,特别是在缺血期应用HBO效果最好,再灌注期应用HBO无效.     

High-density lipoproteins reduce the intestinal damage associated with ischemia/reperfusion and colitis

High-density lipoproteins (HDLs) have been shown to reduce the organ injury and mortality in animal models of shock by reducing the expression of adhesion molecules and proinflammatory enzymes. However, there is limited evidence that HDL treatment reduces inflammation. As inflammation plays an important role in the development of colitis as well as ischemia/reperfusion (I/R) injury of the intestine, we have investigated the effects of HDL in animal models of associated with gut injury and inflammation (splanchnic artery occlusion [SAO] shock and dinitrobenzene sulfonic acid [DNBS]-induced colitis). We report here for the first time that the administration of reconstituted HDLs (recHDLs; 80 mg/kg i.v. bolus 30 min prior to ischemia in the SAO-shock model or 40 mg/kg i.v. every 24 h in the colitis model) exerts potent anti-inflammatory effects (e.g., reduced inflammatory cell infiltration and histological injury, and delayed the development of the clinical signs) in vivo. Furthermore, recHDL reduced the staining for nitrotyrosine and poly(ADP-ribose) (immunohistochemistry) and the expression of intercellular adhesion molecule-1 in the ileum of SAO-shocked rats and in the colon from DNBS-treated rats. Thus, recHDL reduces the inflammation caused by intestinal I/R and colitis. HDLs may represent a novel therapeutic approach for the therapy of inflammation of the gut.     

Elimination of C5aR prevents intestinal mucosal damage and attenuates neutrophil infiltration in local and remote organs

The complement C5a pathway has been shown to be an important mediator of inflammation and tissue injury. To further understand the role of C5a receptor (C5aR) pathway in ischemia/reperfusion (I/R) injury, and to evaluate the potential of antagonizing C5aR to protect from I/R injury, we tested the effect of eliminating C5aR using C5aR knockout (KO) mice and their wild-type (WT) littermates in a superior mesenteric artery occlusion (SMAO) intestinal I/R injury model. C5aR KO and WT mice were subjected to SMAO or sham for 45 min. After 3 h of reperfusion, the percentage of injured ileal villi was twice as high in WT mice subjected to SMAO as compared with the C5aR KO mice. In addition, the number of neutrophils was 34% higher in WT mice subjected to SMAO as compared with the C5aR KO mice. Moreover, ileum and lung myeloperoxidase activities after SMAO were significantly higher in WT than C5aR KO mice. Apoptotic cell death was induced after reperfusion in WT-SMAO and was reduced by more than 50% in C5aR KO mice. The plasma level of TNF-alpha was increased approximately 3.74-fold in WT subjected to SMAO compared with sham. In contrast, the level was increased only approximately 1.18-fold in the C5aR KO mice subjected to SMAO. In conclusion, this study demonstrates that elimination of the C5aR pathway protects the intestine from I/R injury and diminishes intestine-derived pulmonary neutrophil sequestration. Blocking C5aR may be considered as a potential therapeutic intervention for I/R injury.     

Pharmacological preconditioning protects lung injury induced by intestinal ischemia/reperfusion in rat

Intestinal ischemia/reperfusion (IIR) is a critical and triggering event in the development of distal organ dysfunction, frequently involving the lungs. Respiratory failure is a common cause of death and complications after intestinal I/R. Stress protein heme oxygenase-1 (HO-1) confers the protection against a variety of oxidant-induced cell and tissue injuries. The aim of this study was to investigate the hypothesis that the induced HO-1 expression by pharmacological preconditioning with anticancer drug doxorubicin (Dox) could protect the lung injury induced by intestinal I/R. Intravenous administration of Dox induced HO-1 expression in the lungs and high levels of the expression were sustained at least to 48 h after the injection. Therefore, as pharmacological preconditioning, a low dose of Dox was injected intravenously into rats at 48 h before the start of intestinal ischemia. Rats underwent intestinal I/R by superior mesenteric artery occlusion for 120 min followed by 120 min of reperfusion. Preconditioning with Dox significantly ameliorated the lung injury induced by the intestinal I/R. Administration of a specific inhibitor of HO activity reduced the efficacy of the preconditioning. Our results suggest that this improvement may be mediated at least in part by the HO-1 induction. These findings may offer interesting perspectives for patient management In Intestinal surgical operation and intestine transplantation.     

Acetylcholine-induced desensitization of muscarinic contractile response in Guinea pig ileum is inhibited by pertussis toxin treatment.

We investigated the effects of pertussis toxin treatment on acetylcholine-induced desensitization of the muscarinic contractile response in guinea pig ileum. Incubation of the isolated ileum with acetylcholine (30 microM) for 20 min caused a decrease in the sensitivity of the ileum to the contractile action of the muscarinic agonist oxotremorine-M. This desensitization was characterized by an increase in the EC(50) value of oxotremorine-M without a change in its maximal effect. A maximal 4- to 5-fold increase in the EC(50) value of oxotremorine-M was measured at the earliest time investigated after acetylcholine treatment (5 min), and normal sensitivity recovered within approximately 20 min after washout of acetylcholine. Treatment of the ileum with pertussis toxin caused a small increase in the contractile response to oxotremorine-M when measured without prior exposure to acetylcholine. After exposure to acetylcholine, little desensitization was observed in ilea that had been treated with pertussis toxin. Pertussis toxin-treatment caused a small increase in oxotremorine-M-mediated phosphoinositide hydrolysis and a large decrease in oxotremorine-M-mediated inhibition of forskolin-stimulated cAMP accumulation in slices of the longitudinal muscle of the ileum. Exposure of the ileum to acetylcholine had no desensitizing effect on the ability of oxotremorine-M to elicit phosphoinositide hydrolysis, indicating that the mechanism for desensitization of the contractile response occurs at a level downstream from the receptor and phosphoinositide hydrolysis. Our results suggest that activation of muscarinic receptors coupled to pertussis toxin-sensitive G(i) and G(o) is required for most of the desensitization observed in this study.     

膳食纤维肠内营养对全肠道缺血再灌注大鼠肠屏障功能的影响

目的：通过建立大鼠全肠道缺血再灌注模型,探讨膳食纤维肠内营养对肠屏障功能的影响。方法：将实验大鼠随机分成4组,每组10只。第1组为对照组,第2组为缺血再灌注组（I/R组）,该两组为术后24h取材。第3组为普通肠内营养组（EN组）,第4组为膳食纤维肠内营养组（FEN组）,营养支持7d后取材。上述4组均行回、结肠形态学检查,细菌及内毒素移位、结肠固有层淋巴细胞分布检测,用循环D-乳酸法测定肠道通透性。结果：I/R组大鼠回、结肠黏膜萎缩,腺体稀疏,黏膜下层水肿、出血。FEN组肠黏膜形态学变化好于EN组。I/R组细菌移位率、血浆D-乳酸、血浆内毒素显著高于对照组;FEN组D-乳酸、内毒素水平低于EN组。I/R组结肠固有层CD4＋、CD8＋T淋巴细胞显著低于其余各组。FEN组CD4＋、CD8＋T淋巴细胞较EN组增多。结论：添加膳食纤维的肠内营养在维护肠黏膜屏障、改善肠道免疫功能、防止细菌及内毒素移位方面作用优于单纯肠内营养。膳食纤维能提高结肠局部免疫功能。     

Prevention of hemorrhagic shock-induced intestinal tissue injury by glutamine via heme oxygenase-1 induction

Hemorrhagic shock (HS) is an oxidative stress that causes intestinal tissue injury. Heme oxygenase 1 (HO-1) is induced by oxidative stress and is thought to play an important role in the protection of tissues from oxidative injury. We previously reported the ileum to be the most susceptible to HS-induced tissue injury site in the intestine because HO-1 induction is the lowest at this site. We also previously demonstrated that glutamine (GLN) significantly induced HO-1 in the lower intestinal tract. In the present study, we investigated whether GLN pretreatment improves HS-induced intestinal tissue injury in the ileum by HO-1 induction. Treatment of rats with GLN (0.75 g/kg, i.v.) markedly induced functional HO-1 protein in mucosal epithelial cells in the ileum. Glutamine treatment before HS (MAP of 30 mmHg for 60 min) significantly ameliorated HS-induced mucosal inflammation and apoptotic cell death in the ileum, as judged by significant decreases in gene expression of TNF-alpha, iNOS, intercellular adhesion molecule 1, and vascular cell adhesion molecule 1, myeloperoxidase activity, the number of infiltrated neutrophils, DNA fragmentation by in situ oligo ligation assay, and activated caspase-3 expression, and by increases in gene expression of IL-10 and Bcl-2. In contrast, treatment with tin mesoporphyrin, a specific inhibitor of HO activity, abolished the beneficial effect of GLN pretreatment. These findings indicate that GLN pretreatment significantly ameliorated tissue injury in the ileum after HS by inducing HO-1. Glutamine treatment may thus protect mucosal cells from HS-induced oxidative damage via the anti-inflammatory and antiapoptotic properties of HO-1.     

左旋精氨酸对兔肺缺血/再灌注损伤时细胞凋亡的影响

目的观察左旋精氨酸对免肺缺血／再灌注损伤中细胞凋亡的影响。方法复制单侧免肺缺血／再灌注损伤模型．随机分为三组：对照组（C组）、缺血／再灌注组（I／R组）和左旋精氨酸组（L—Arg组），每组10只。再灌注180min时取肺组织，观察超氧化物歧化酶（SOD）活性、丙二醛（MDA）浓度、一氧化氮（NO）含量、肺湿干比（W／D）、肺泡损伤数定量评价指标（IQA）及肺组织细胞凋亡指数（At）。结果I／R组与C组比较，SOD活性、NO含量明显降低（P〈0．01），MDA、W／D、IQA、AI明显升高（P〈0．01），L—Arg组与I／R组相比较，SOD活性、NO含量均明显升高（P〈0．01），MDA、W／D、IQA、AI不同程度降低（P〈0．05）。结论左旋精氨酸可通过提高体内NO水平、降低氧自由基水平、减轻脂质过氧化反应，抑制肺组织细胞凋亡，从而减轻肺损伤。     

Evaluation of intestinal preconditioning in a porcine model using classic ischemic preconditioning or lung recruitment maneuvers

To test the hypotheses that repeated brief intestinal ischemic insults would elicit an intestinal preconditioning response to a subsequent intestinal I/R injury and that a similar response would be elicited by repeated lung recruitment maneuvers (RMs). Randomized experimental controlled animal study. University hospital animal laboratory. Eighteen anesthetized pigs. Animals were randomized to one of three groups, with six animals in each group. Control group 75-min superior mesenteric artery (SMA) occlusion followed by 60-min reperfusion. Ischemic preconditioning group, three 5-min-long SMA occlusions preceding 75-min SMA occlusion and 60-min reperfusion. Recruitment maneuver (RM) group, three 2-min-long RMs preceding 75-min SMA occlusion and 60-min reperfusion. We measured systemic and mesenteric hemodynamic parameters, jejunal mucosal perfusion, net mesenteric lactate flux, jejunal tissue oxygen tension, and mesenteric oxygenation. Every 15 min, jejunal microdialysate samples were collected and analyzed for glucose, lactate, and glycerol. Jejunal tissue samples were collected postmortem. After occlusion of SMA, regional parameters in all groups indicated abolished perfusion and gradually increasing intraluminal microdialysate lactate and glycerol levels. At reperfusion, regional parameters indicated mesenteric hyperperfusion, whereas microdialysis markers of mucosal anaerobic metabolism and cell injury decreased, although not reaching baseline. Histological examination revealed severe mucosal injury in all groups. There were no significant differences between groups in the observed parameters. No protective preconditioning response could be observed when performing repeated brief intestinal ischemic insults or repeated lung RMs before an intestinal I/R injury.     

Application of heme oxygenase-1, carbon monoxide and biliverdin for the prevention of intestinal ischemia/reperfusion injury

Intestinal ischemia/reperfusion (I/R) injury occurs frequently in a variety of clinical settings, including mesenteric artery occlusion, abdominal aneurism surgery, trauma, shock, and small intestinal transplantation, and is associated with substantial morbidity and mortality. Although the exact mechanisms involved in the pathogenesis of intestinal I/R injury have not been fully elucidated, it is generally believed that polymorphonuclear neutrophils, pro-inflammatory cytokines, and mediators generated in the setting of oxidative stress, such as reactive oxygen species (ROS), play important roles. Heme oxygenase (HO) is the rate-limiting enzyme that catalyzes the degradation of heme into equimolar quantities of biliverdin and carbon monoxide (CO), while the central iron is released. An inducible form of HO (HO-1), biliverdin, and CO, have been shown to possess generalized endogenous anti-inflammatory activities and provide protection against intestinal I/R injury. Further, recent observations have demonstrated that exogenous HO-1 expression, as well as exogenously administered CO and biliverdin, have potent cytoprotective effects on intestinal I/R injury as well. Here, we summarize the currently available data regarding the role of the HO system in the prevention intestinal I/R injury.