Small Intestinal Ischemia-reperfusion Research Articles

Si-based agent alleviated small bowel ischemia–reperfusion injury through antioxidant effects

The progression of small bowel ischemia–reperfusion (IR) injury causes cells in the intestinal tract to undergo necrosis, necessitating surgical resection, which may result in loss of intestinal function. Therefore, developing therapeutic agents that can prevent IR injury at early stages and suppress its progression is imperative. As IR injury may be closely related to oxidative stress, antioxidants can be effective therapeutic agents. Our silicon (Si)-based agent, an antioxidant, generated a large amount of hydrogen in the intestinal tract for a prolonged period after oral administration. As it has been effective for ulcerative colitis, renal failure, and IR injury during skin flap transplantation, it could be effective for small intestinal IR injury. Herein, we investigated the efficacy of an Si-based agent in a mouse model of small intestinal IR injury. The Si-based agent suppressed the apoptosis of small intestinal epithelial cells by reducing the oxidative stress induced by IR injury. In addition, the thickness of the mucosal layer in the small intestine of the Si-based agent-administered group was significantly higher than that in the untreated group, revealing that Si-based agent is effective against small intestinal IR injuries. In the future, Si-based agents may improve the success rate of small intestine transplantation.

Transplanted hair follicle mesenchymal stem cells alleviated small intestinal ischemia–reperfusion injury via intrinsic and paracrine mechanisms in a rat model

Background: Small intestinal ischemia-reperfusion (IR) injury is a common intestinal disease with high morbidity and mortality. Mesenchymal stem cells (MSCs) have been increasingly used in various intestinal diseases. This study aimed to evaluate the therapeutic effect of hair follicle MSCs (HFMSCs) on small intestinal IR injury. Methods: We divided Sprague–Dawley rats into three groups: the sham group, IR group and IR + HFMSCs group. A small intestinal IR injury rat model was established by clamping of the superior mesenteric artery (SMA) for 30 min and reperfusion for 2 h. HFMSCs were cultured in vitro and injected into the rats through the tail vein. Seven days after treatment, the intrinsic homing and differentiation characteristics of the HFMSCs were observed by immunofluorescence and immunohistochemical staining, and the paracrine mechanism of HFMSCs was assessed by Western blotting and enzyme-linked immunosorbent assay (ELISA). Results: A small intestinal IR injury model was successfully established. HFMSCs could home to damaged sites, express proliferating cell nuclear antigen (PCNA) and intestinal stem cell (ISC) markers, and promote small intestinal ISC marker expression. The expression levels of angiopoietin-1 (ANG1), vascular endothelial growth factor (VEGF) and insulin growth factor-1 (IGF1) in the IR + HFMSCs group were higher than those in the IR group. HFMSCs could prevent IR-induced apoptosis by increasing B-cell lymphoma-2 (Bcl-2) expression and decreasing Bcl-2 homologous antagonist/killer (Bax) expression. Oxidative stress level detection showed that the malondialdehyde (MDA) content was decreased, while the superoxide dismutase (SOD) content was increased in the IR + HFMSCs group compared to the IR group. An elevated diamine oxidase (DAO) level reflected the potential protective effect of HFMSCs on the intestinal mucosal barrier. Conclusion: HFMSCs are beneficial to alleviate small intestinal IR injury through intrinsic homing to the small intestine and by differentiating into ISCs, via a paracrine mechanism to promote angiogenesis, reduce apoptosis, regulate the oxidative stress response, and protect intestinal mucosal function potentially. Therefore, this study suggests that HFMSCs serve as a new option for the treatment of small intestinal IR injury.

Possible effects of clinoptilolite on small intestinal ischemia-reperfusion injury caused by experimental mesenteric artery occlusion

Abstract Objectives Mesenteric ischemia is a surgical emergency caused by poor blood supply to the intestines. In ischemia, the decrease in blood flow to the tissue causes acidosis and cell death through anaerobic metabolism. Clinoptilolite is one of the most abundant natural zeolites, and it is used for its ion exchange and adsorbent properties. Clinoptilolite has been reported to have an immune-enhancing, anti-carcinogenic, and antioxidant effect in-vitro/in-vivo studies. Clinoptilolite’s histological and biochemical effects on ischemic small intestines. Methods The experimental animals were randomly divided into sham, control, and clinoptilolite treatment group. Clinoptilolite was administered intraperitoneally after ischemia/reperfusion. Cardiac blood was stored for biochemical analysis. Total antioxidant levels and total oxidant levels were analyzed from the sera taken from groups. Tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) expressions in blood samples were determined by RT-qPCR. At the end of the reperfusion, terminal ileum tissues were taken for histological tests. Results The mean TNF-α expression level was 3.89 in the control group and 2.91 in the clinoptilolite treatment group. The mean IL-6 expression levels were 2.32 in the control group and 1.49 in the clinoptilolite treatment group. Conclusions clinoptilolite administration provided healing in the rat ischemia-reperfusion injury model.

Protein O-GlcNAcylation alleviates small intestinal injury induced by ischemia-reperfusion and oxygen-glucose deprivation

Protein O-GlcNAcylation is a dynamic post-translational protein modification that regulates fundamental cellular functions in both normal physiology and diseases. The levels of protein O-GlcNAcylation are determined by flux of the hexosamine biosynthetic pathway (HBP), which is a branch of glycolysis, and are directly controlled by a pair of enzymes: O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA). An increase in protein O-GlcNAcylation has been shown to have protective effects on ischemia-related insults in the heart and brain. To determine whether O-GlcNAcylation plays a beneficial role in ischemia-reperfusion (IR)-induced intestinal injury, we used pharmacological manipulation of O-GlcNAc to induce loss- and gain-of-function conditions and evaluated the viability and apoptosis of intestinal epithelioid cells in an in vitro oxygen-glucose deprivation (OGD) model and tissue injury grade in a small intestinal ischemia-reperfusion (SIIR) mouse model. We found that 1) Upregulation of O-GlcNAcylation induced by glucosamine (GlcN, increase in HBP flux) or thiamet G (an OGA inhibitor) enhanced intestinal cell survival in the OGD model. In contrast, downregulation of O-GlcNAcylation induced by DON (due to a reduction in HBP flux) or OMSI-1 (an OGT inhibitor) made the cells more susceptible to hypoxia injury. 2) Reducing the increase in O-GlcNAcylation levels with a combination of either GlcN with DON or thiamet G with OMSI-1 partly canceled its protective effect on OGD-induced cell injury. 3) In the in vivo SIIR mouse model, GlcN augmented intestinal protein O-GlcNAcylation and significantly alleviated intestinal injury by inhibiting cell apoptosis. These results indicate that acute increases in protein O-GlcNAcylation confer protection against intestinal ischemia insults, suggesting that O-GlcNAcylation, as an endogenous stress sensor, could be a universal protective mechanism and could be a potential therapeutic target for intestinal ischemic disease.

Effect of rutin on experimentally induced small intestinal ischemia reperfusion injury in rats: A biochemical and histopathological evaluation

Effect of rutin on experimentally induced small intestinal ischemia reperfusion injury in rats: A biochemical and histopathological evaluation

Protective effects of dexmedetomidine on small intestinal ischaemia-reperfusion injury in horses.

Strangulating small intestinal lesions in the horse have increased morbidity and mortality compared to nonstrangulating obstructions due to mucosal barrier disruption and subsequent endotoxaemia. To investigate protective effects of dexmedetomidine on small intestinal ischaemia-reperfusion injury in the horse. Randomised, controlled, experimental study. Eighteen systemically healthy horses were randomly assigned to three groups: control, preconditioning, and post-conditioning. During isoflurane anaesthesia, complete ischaemia was induced in a 1-m segment of jejunum for 90minutes. Horses in the preconditioning and post-conditioning groups received dexmedetomidine (3.5µg/kg followed by 7µg/kg/h) before (preconditioning) or after beginning ischaemia (post-conditioning), and during reperfusion. Jejunal biopsies were collected before ischaemia (baseline-1), at the end of the ischaemic period (ischaemia), and 30minutes after reperfusion (reperfusion-1). Additional biopsies were taken 24hours after reperfusion from ischaemia-reperfusion-injured jejunum (reperfusion-2). Epithelial injury was scored histologically, and morphometric analyses were used to calculate villus surface area (VSA) denuded of epithelium. Data were analysed using analysis of variance, Kruskal-Wallis and Wilcoxon two-sample tests. In the control group, epithelial injury scores and percentage of VSA denudation for ischaemia-reperfusion-injured jejunum were higher compared to baseline-1 at all time points. The ischaemia and both reperfusion samples from the pre- and post-conditioning groups had lower epithelial injury scores and percentage of VSA epithelial denudation compared to the control group, with no difference from baseline-1 at any time point for the preconditioning group. Preconditioning has limited application in the clinical setting with naturally occurring strangulating small intestinal lesions. Dexmedetomidine was protective for small intestinal ischaemia-reperfusion injury in the horse when administered before or during ischaemia.

Ischaemic preconditioning and pharmacological preconditioning with dexmedetomidine in an equine model of small intestinal ischaemia-reperfusion.

Small intestinal strangulation associated with ischaemia-reperfusion injury (IRI) is common in horses. In laboratory animals IRI can be ameliorated by ischaemic preconditioning (IPC) and pharmacological preconditioning (PPC) with dexmedetomidine. The aim of this study was to determine the effect of PPC with dexmedetomidine or IPC in an equine model of small intestinal ischaemia-reperfusion (IR). In a randomized controlled experimental trial, 15 horses were assigned to three groups: control (C), IPC, and PPC with dexmedetomidine (DEX). All horses were placed under general anaesthesia and 90% jejunal ischaemia was induced for 90 minutes, followed 30 minutes of reperfusion. In group IPC, three short bouts of ischaemia and reperfusion were implemented, and group DEX received a continuous rate infusion of dexmedetomidine prior to the main ischaemia. Jejunal biopsies were collected before ischaemia (P), and at the end of ischaemia (I) and reperfusion (R). Mucosal injury was assessed by the Chiu-Score, inflammatory cells were stained by cytosolic calprotectin. The degree of apoptosis and cell necrosis was assessed by cleaved-caspase-3 and TUNEL. Parametric data were analyzed by two-way ANOVA for repeated measurements followed by Dunnetts t-test. Non parametric data were compared between groups at the different time points by a Kruskal-Wallis-Test and a Wilcoxon-2-Sample-test. The mucosal injury score increased during I in all groups. After reperfusion, IRI further progressed in group C, but not in IPC and DEX. In all groups the number of cleaved caspase-3 and TUNEL positive cells increased from P to I. The number of TUNEL positive cells were lower in group DEX compared to group C after I and R. Infiltration with calprotectin positive cells was less pronounced in group DEX compared to group C, whereas in group IPC more calprotectin positive cells were seen. In conclusion, IPC and DEX exert protective effects in experimental small intestinal ischaemia in horses.

Histopathology of human small intestinal and colonic ischemia-reperfusion: Experiences from human IR-models.

Intestinal ischemia-reperfusion (IR) injury is a frequent, but potentially life-threatening condition. Although much has been learned about its pathophysiology from animal IR models, the translation to the human setting is imperative for better understanding of its etiology. This could provide us with new insight into development of early detection and potential new therapeutic strategies. Over the past decade, we have studied the pathophysiology of human small intestinal and colonic ischemia-reperfusion (IR) in newly developed human in vivo IR models. In this review, we give an overview of new insights on the sequelae of human intestinal IR, with particular attention for the differences in histopathology between small intestinal and colonic IR.

Autodigestion by migrated trypsin is a major factor in small intestinal ischemia-reperfusion injury

BackgroundThe pathophysiological role of pancreatic digestive hydrolases in intestinal ischemia-reperfusion (I/R) injury is still not clear. Here, we studied whether ischemia-induced injury to the small intestine can be explained by the autodigestion hypothesis. Materials and methodsMesenteric I/R was induced in rats by superior mesenteric artery occlusion (90 min) and reopening (120 min). Thirty minutes before superior mesenteric artery occlusion, aprotinin (14.7 mg/kg), orlistat (5 mg/kg), and their combination or α1-proteinase inhibitor (60 mg/kg) were injected into the lumen of the small intestine. Systemic and vital parameters, intestinal microcirculation, and mucosal barrier function were monitored during the observation phase; markers of small intestinal injury, as well as trypsin-, chymotrypsin-, elastase-, and lipase-like activities in intestinal effluates were assessed at the end. ResultsThe pattern of small intestinal injury correlated inversely with the local alterations in microvascular tissue perfusion and corresponded with the intestinal distribution of trypsin-like activity. Aprotinin almost completely inhibited trypsin-like activity (P < 0.05) and significantly reduced intestinal tissue injury. Combined with orlistat, it also increased the postischemic blood pressure (P < 0.05) but not the intestinal barrier function. Macroscopic as well as the histologic alterations were decreased by α1-proteinase inhibitor, which significantly improved postischemic blood pressure (P < 0.05). ConclusionsThe I/R-induced pattern of small intestinal injury is likely to result from both local differences in tissue ischemia and the digestive activity of migrated pancreatic trypsin. Therefore, administration of aprotinin and orlistat into ischemic small intestines may be a therapeutic option in patients with a poor diagnosis.

Liver injury following small intestinal ischemia reperfusion in rats is attenuated by Pistacia lentiscus oil: antioxidant and anti-inflammatory effects

Context: Intestinal ischemia-reperfusion (IIR) not only leads to severe intestine damage but also induced subsequent destruction of remote organs.Objective: We investigated the protective effect of Pistascia lentiscus L. (Anacardiaceae) oil on IIR.Materials and methods: Wistar rats were divided into three groups: sham, intestinal IR and P. lentiscus pretreatment (n = 18 each). In the pretreatment group, oil was administered 1 h before induction of warm ischemia.Results: IIR led to severe liver damage manifested as a significant (p < .05) increase of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels. Pistacia lentiscus oil decreased the visible intestinal damage, as well as a significant decrease in serum AST and ALT levels. In addition, Pistacia lentiscus reduce liver injury, as evidenced by the decrease in liver tissue myeloperoxidase activity and lipoperoxidation (MDA) level.Conclusion: Pistascia lentiscus attenuates liver injury induced by IIR, attributable to the antioxidant and anti-inflammatory effect.

Postconditioning: “Toll-erating” mesenteric ischemia-reperfusion injury?

Postconditioning may prove to be a suitable method to decrease ischemia-reperfusion injury of intestine after mesenteric arterial occlusion. Toll-like-receptor-4 is involved in the pathophysiology of organ damage after ischemia-reperfusion; therefore, the aim of our study was to investigate the effect of postconditioning on the mucosal expression of toll-like-receptor-4. Male Wistar rats (n=10/group) underwent 60minutes of superior mesenteric artery occlusion followed by 6hours of reperfusion in 3 groups: sham-operated, ischemia-reperfusion, and a postconditioned group. Postconditioning was performed by 6 alternating cycles of 10seconds of reperfusion/reocclusion. Blood and tissue samples were collected at the end of reperfusion. Intestinal histopathologic changes and immunohistochemical expression of mucosal caspase-3, antioxidant status, and protein levels of high-mobility group box-1 and toll-like-receptor-4 were assessed. Immunofluorescent labeling and confocal microscopic analysis of toll-like-receptor-4 were performed. Mucosal and serum levels of interleukin-6 and tumor necrosis factor-α protein were measured. Histologic alterations in the postconditioned group were associated with decreased caspase-3 positivity, less toll-like-receptor-4 mRNA, and less protein expression of high-mobility group box-1 and toll-like-receptor-4 in the intestinal villi compared with the ischemia-reperfusion group. Furthermore, a significantly improved antioxidant state of the intestinal mucosa and less mucosal and serum protein levels of interleukin-6 and tumor necrosis factor-α were detected in the postconditioned group. Small intestinal ischemia-reperfusion injury in male Wistar rats caused by the occlusion of the superior mesenteric artery was ameliorated by the use of postconditioning, showing a more favorable inflammatory response, which may be attributed to the decreased mucosal expression of toll-like-receptor-4.

Computed Tomography Perfusion Imaging Detection of Microcirculatory Dysfunction in Small Intestinal Ischemia-Reperfusion Injury in a Porcine Model.

ObjectiveTo evaluate multi-slice computed tomography (CT) perfusion imaging (CTPI) for identifying microcirculatory dysfunction in small intestinal ischemia−reperfusion (IR) injury in a porcine model.Materials and MethodsFifty-two pigs were randomly divided into 4 groups: (1) the IR group (n = 24), where intestinal ischemia was induced by separating and clamping the superior mesenteric artery (SMA) for 2 h, followed by reperfusion for 1, 2, 3, and 4 h (IR-1h, IR-2h, IR-3h, and IR-4h; n = 6, respectively); (2) the sham-operated (SO) group (n = 20), where the SMA was separated without clamping and controlled at postoperative 3, 4, 5, and 6 h (SO-3h, SO-4h, SO-5h, and SO-6h; n = 5, respectively); (3) the ischemia group (n = 4), where the SMA was separated and clamped for 2 h, without reperfusion, and (4) baseline group (n = 4), an additional group that was not manipulated. Small intestinal CTPI was performed at corresponding time points and perfusion parameters were obtained. The distal ileum was resected to measure the concentrations of malondialdehyde (MDA) and superoxide dismutase (SOD) and for histopathological examination.ResultsThe perfusion parameters of the IR groups showed significant differences compared with the corresponding SO groups and the baseline group (before ischemia). The blood flow (BF), blood volume (BV), and permeability surface (PS) among the 4 IR groups were significantly different. BF and BV were significantly negatively correlated with MDA, and significantly positively correlated with SOD in the IR groups. Histopathologically, the effects of the 2-h ischemic loops were not significantly exacerbated by reperfusion.ConclusionCTPI can be a valuable tool for detecting microcirculatory dysfunction and for dynamic monitoring of small intestinal IR injury.

Methane attenuates myocardial ischemia injury in rats through anti-oxidative, anti-apoptotic and anti-inflammatory actions

Myocardial infarction (MI) remains the most frequent cardiovascular disease with high mortality. Recently, methane has been shown protective effects on small intestinal ischemia–reperfusion injury. We hypothesized that methane-rich saline (MS) could protect the myocardium again MI via its anti-oxidative, anti-apoptotic and anti-inflammatory effects. In experiment 1, tetrazolium chloride staining and detection of myocardial enzymes and oxidative and inflammatory parameters were performed at 12h after MI to determine the optimal dose at which intraperitoneal MS exerted the best protective effects on MI. In experiment 2, rats were treated with 10ml/kg MS. Myocyte apoptosis was detected 72h after MI, and cardiac function and myocardial remodeling were evaluated 4 weeks after MI. Results showed different dose of MS reduced infarct area, decreased myocardial enzymes, inhibited inflammation and oxidative stress following MI. The optimal dose of MS was 10mg/kg. Moreover, treatment with 10mg/kg MS for 3 days significantly reduced myocyte apoptosis, improved cardiac function and inhibited myocardial remodeling (reduced anterior wall thickness, attenuated myocyte hypertrophy, and decreased myocardial collagen). MS protects the myocardium of MI rats via its anti-oxidative, anti-inflammatory, anti-apoptotic and anti-remodeling activities. Thus, MS provides a novel and promising strategy for the treatment of ischemic heart diseases.

The Human Colon Is More Resistant to Ischemia-reperfusion-induced Tissue Damage Than the Small Intestine: An Observational Study.

Aim of this study was to draw comparisons between human colonic and jejunal ischemia-reperfusion sequelae in a human in vivo experimental model. In patients, colonic ischemia-reperfusion generally has a milder course than small intestinal ischemia-reperfusion. It is unclear which pathophysiologic processes are responsible for this difference. In 10 patients undergoing colonic surgery and 10 patients undergoing pancreaticoduodenectomy, 6 cm colon or jejunum was isolated and exposed to 60 minutes ischemia followed by various reperfusion periods. Morphology (hematoxylin and eosin), apoptosis (M30), tight junctions (zonula occludens 1), and neutrophil influx (myeloperoxidase) were assessed using immunohistochemistry. Quantitative polymerase chain reaction and enzyme-linked immunosorbent assay were performed for interleukin-6 and tumor necrosis factor-α. Hematoxylin and eosin staining revealed intact colonic epithelial lining, but extensive damage in jejunal villus tips after 60 minutes ischemia. After reperfusion, the colonic epithelial lining was not affected, whereas the jejunal epithelium was seriously damaged. Colonic apoptosis was limited to scattered cells in surface epithelium, whereas apoptosis was clearly observed in jejunal villi and crypts, (42 times more M30 positivity compared with colon, P < 0.01). Neutrophil influx and increased tumor necrosis factor-α mRNA expression were observed in jejunum after 30 and 120 minutes of reperfusion (P < 0.05). Interleukin-6 mRNA expression was increased in jejunum after 120 minutes of reperfusion (3.6-fold increase, P < 0.05), whereas interleukin-6 protein expression was increased in both colon (1.5-fold increase, P < 0.05) and small intestine (1.5-fold increase, P < 0.05) after 30 and 120 minutes of reperfusion. Human colon is less susceptible to IR-induced tissue injury than small intestine.

Monitoring dynamic alterations in calcium homeostasis by T1-mapping manganese-enhanced MRI (MEMRI) in the early stage of small intestinal ischemia-reperfusion injury.

Manganese-enhanced MRI studies have proven to be useful in monitoring physiological activities associated with calcium ions (Ca(2+)) due to the paramagnetic property of the manganese ion (Mn(2+)), which makes it an excellent probe of Ca(2+) . In this study, we developed a method in which a Mn(2+)-enhanced T1 -map MRI could enable the monitoring of Ca(2+) influx during the early stages of intestinal ischemia-reperfusion (I/R) injury. The Mn(2+) infusion protocol was optimized by obtaining dose-dependent and time-course wash-out curves using a Mn(2+)-enhanced T1-map MRI of rabbit abdomens following an intravenous infusion of 50 mmol/l MnCl2 (5-10 nmol/g body weight (BW)). In the rabbit model of intestinal I/R injury, T1 values were derived from the T1 maps in the intestinal wall region and revealed a relationship between the dose of the infused MnCl2 and the intestinal wall relaxation time. Significant Mn(2+) clearance was also observed over time in control animals after the infusion of Mn(2+) at a dose of 10 nmol/g BW. This technique was also shown to be sensitive enough to monitor variations in calcium ion homeostasis in vivo after small intestinal I/R injury. The T1 values of the intestinal I/R group were significantly lower (P < 0.05) than that of the control group at 5, 10, and 15 min after Mn(2+) infusion. Our data suggest that MnCl2 has the potential to be an MRI contrast agent that can be effectively used to monitor changes in intracellular Ca(2+) homeostasis during the early stages of intestinal I/R injury.

The role of mitochondrial permeability transition pore in ischemic post-conditioning for counteracting small intestinal ischemia-reperfusion injury in rabbits

Objective To investigate the role of mitochondrial permeability transition pore (mPTP)in ischemic post-conditioning for counteracting small intestinal ischemia-reperfusion(I/ R)injury in rabbits. Methods Forty New Zealand rabbits were randomly divided into sham-operated group(Sham group), I/R group,ischemic post-conditioning group(IPO group), mPTP inhibitor cyclosporine A group(Cs A group), and IPO+ mPTP agonist atraotydin group(IPO+ Atr group).Parts of small intestine tissues were collected from each group of rabbits after intervention for hematoxylin-eosin(HE) staining. Malondialdehyde(MDA) activity in small intestine tissue was measured by the relevant kit.The mitochondria were isolated and mPTP opening was detected by relevant kits.Intestinal mucosal injury was observed by Chiu's grade 6 scoring method.The apoptosis of intestinal epithelial cells was examined by Td T-mediated d UTP nick end labeling(TUNEL) assay. Results As compared with Sham group, mPTP opening in I/R group was significantly increased(3. 53±0. 36 vs. 1. 37±0. 16, P< 0. 05); MDA activity was significantly increased[(0. 98±0. 14) nmol/mg vs. (0. 34±0. 03) nmol/mg, P< 0. 05]; intestinal mucosa score was significantly increased(4. 66± 0. 41 vs.0. 92±0. 58, P< 0. 05); apoptosis index of intestinal cells was significantly increased [(60. 34±6. 02)% vs.(4. 65±1. 68)%, P< 0. 05].As compared with I/R group, mPTP openings in IPO group and Cs A group were significantly decreased(2. 32±0. 23 and 2. 62±0. 18 vs.3. 53± 0. 36, P< 0. 05); MDA activity was significantly decreased[(0. 55±0. 04) and(0. 62±0. 06) nmol/mg vs.(0. 98±0. 14) nmol/mg, P< 0. 05]; intestinal mucosa score was significantly decreased(3. 25±0. 27 and 3. 52±0. 55 vs.4. 66±0. 41, P< 0. 05); apoptosis of intestinal cells was significantly decreased[(28. 33±3. 20)% and(20. 49±4. 10)% vs.(60. 34±6. 02)%, P< 0. 05]. As compared with IPO group, mPTP openings in IPo+ Atr group were significantly increased(2. 32 ±0. 23 vs.1. 05±0. 16, P< 0. 05); MDA activity was significantly increased[(1. 08±0. 18) vs. (0. 55±0. 04) nmol/mg, P< 0. 05]; intestinal mucosa score was significantly increased(4. 57± 0. 32 vs.3. 25±0. 27, P< 0. 05); apoptosis index of intestinal cells was significantly increased [(40. 35±2. 18)% vs.(28. 33±3. 20)%,P< 0. 05]. Conclusion The mechanism of ischemic post-conditioning for counteracting intestinal ischemia-reperfusion injury in rabbits may be associated with the inhibition of mitochondrial permeability transition pore opening. Key words: Mitochondrial permeability transition pore; Ischemic post-conditioning; Intestine ischemia; Reperfusion injury

Propofol Attenuates Small Intestinal Ischemia Reperfusion Injury through Inhibiting NADPH Oxidase Mediated Mast Cell Activation.

Both oxidative stress and mast cell (MC) degranulation participate in the process of small intestinal ischemia reperfusion (IIR) injury, and oxidative stress induces MC degranulation. Propofol, an anesthetic with antioxidant property, can attenuate IIR injury. We postulated that propofol can protect against IIR injury by inhibiting oxidative stress subsequent from NADPH oxidase mediated MC activation. Cultured RBL-2H3 cells were pretreated with antioxidant N-acetylcysteine (NAC) or propofol and subjected to hydrogen peroxide (H2O2) stimulation without or with MC degranulator compound 48/80 (CP). H2O2 significantly increased cells degranulation, which was abolished by NAC or propofol. MC degranulation by CP further aggravated H2O2 induced cell degranulation of small intestinal epithelial cell, IEC-6 cells, stimulated by tryptase. Rats subjected to IIR showed significant increases in cellular injury and elevations of NADPH oxidase subunits p47phox and gp91phox protein expression, increases of the specific lipid peroxidation product 15-F2t-Isoprostane and interleukin-6, and reductions in superoxide dismutase activity with concomitant enhancements in tryptase and β-hexosaminidase. MC degranulation by CP further aggravated IIR injury. And all these changes were attenuated by NAC or propofol pretreatment, which also abrogated CP-mediated exacerbation of IIR injury. It is concluded that pretreatment of propofol confers protection against IIR injury by suppressing NADPH oxidase mediated MC activation.

Effects of anti-histamine treatment on liver injury triggered by small intestinal ischemia reperfusion in rats.

Mast cell (MC) degranulation has been implicated in small intestinal ischemia reperfusion (IIR) injury, therein, inhibiting overproduction of histamine released from activated MC may provide promising strategies against IIR-mediated liver injuries. The aim of the present study was to explore whether anti-histamine treatment contribute to attenuating IIR-mediated liver injury. Adult SD rats were randomized into sham-operated group (S group), sole IIR group (IIR group), and IIR treated with Ketotifen, a histamine antagonist (IIR+K group), Cromolyn Sodium, a MC stabilizer (IIR+C group), and Compound 48/80, a MC degranulator (IIR+CP group), respectively. IIR was induced by superior mesenteric artery occlusion for 75 min followed by 4 h of reperfusion. The agents were intravenously administrated 5 min before reperfusion to induce different levels of histamine. Subsequently, serum concentrations of ALT, AST and histamine; levels of LDH,TNF-α, IL-8 and MDA as well as SOD activities in the liver were assessed. Histopathologic changes were also evaluated. IIR resulted in severe liver injury as demonstrated by significant increases in injury scores, with concomitant significant increases in serum ALT, AST and histamine levels, as well as LDH, TNF-α, IL-8, and MDA levels in the liver, accompanied by reduction in SOD activities (all P < 0.05, IIR vs. S). Treatments by Ketotifen and Cromolyn Sodium similarly markedly alleviated IIR-mediated liver injury as confirmed by significant reduction of the above biomedical changes whereas Compound 48/80 further aggravated IIR-mediated liver injury by dramatically enhancing the above biomedical changes. Data of our study suggest that anti-histamine treatments may provide promising benefits in alleviating liver injury triggered by IIR.

Pivotal role of mast cell carboxypeptidase A in mediating protection against small intestinal ischemia–reperfusion injury in rats after ischemic preconditioning

Aim of the studyMast cell (MC) degranulation contributes to the protection mediated by ischemic preconditioning (IPC); however, the precise mechanisms underlying this protection remain largely unknown. Mast cell carboxypeptidase A (MC-CPA) is released solely from MCs and plays a critical role in degrading toxins and endothelin 1 (ET-1). The present study sought to explore whether MC-CPA is involved in the process of IPC in a rodent model of small intestinal ischemia reperfusion (IIR) injury. Materials and methodsIIR injuries were induced in Sprague–Dawley rats by clamping the superior mesenteric artery for 60 min followed by reperfusion for 2 h. One cycle of 10 min intestinal ischemia and 10 min of reperfusion was used in the IPC group, and the MC stabilizer cromolyn sodium and MC potato carboxypeptidase inhibitor were administered before the start of IPC. At the end of experiment, intestine tissue was obtained for assays of the MC-CPA3, tumor necrosis factor-α, interleukin-6, and ET-1 contents and myeloperoxidase activities. Intestinal histologic injury scores and MC degranulation were assessed. Apoptosis indices and cleaved caspase- 3 protein expressions were quantified. ResultsIIR resulted in severe injury, as evidenced by significant increases in injury scores and MC-CPA3, tumor necrosis factor-α, interleukin-6, and ET-1 contents that were accompanied with concomitant elevations in cleaved caspase 3 expression, apoptosis indices, and myeloperoxidase activities. IPC induced a significant increase in MC-CPA3, induced MC degranulation, and attenuated IIR injury by downregulating IIR-induced biochemical changes, whereas cromolyn sodium and potato carboxypeptidase inhibitor abolished the IPC-mediated changes. ConclusionsThese data suggest that IPC protected against IIR injury via the MC degranulation-mediated release of MC-CPA.

Protective effects of l-alpha-glycerylphosphorylcholine on ischaemia–reperfusion-induced inflammatory reactions

Choline-containing dietary phospholipids, including phosphatidylcholine (PC), may function as anti-inflammatory substances, but the mechanism remains largely unknown. We investigated the effects of L-alpha-glycerylphosphorylcholine (GPC), a deacylated PC derivative, in a rodent model of small intestinal ischaemia-reperfusion (IR) injury. Anaesthetized Sprague-Dawley rats were divided into control, mesenteric IR (45 min mesenteric artery occlusion, followed by 180 min reperfusion), IR with GPC pretreatment (16.56 mg kg⁻¹ GPC i.v., 5 min prior to ischaemia) or IR with GPC post-treatment (16.56 mg kg⁻¹ GPC i.v., 5 min prior to reperfusion) groups. Macrohaemodynamics and microhaemodynamic parameters were measured; intestinal inflammatory markers (xanthine oxidoreductase activity, superoxide and nitrotyrosine levels) and liver ATP contents were determined. The IR challenge reduced the intestinal intramural red blood cell velocity, increased the mesenteric vascular resistance, the tissue xanthine oxidoreductase activity, the superoxide production, and the nitrotyrosine levels, and the ATP content of the liver was decreased. Exogenous GPC attenuated the macro- and microcirculatory dysfunction and provided significant protection against the radical production resulting from the IR stress. The GPC pretreatment alleviated the hepatic ATP depletion, the reductions in the mean arterial pressure and superior mesenteric artery flow, and similarly to the post-treatments with GPC, also decreased the xanthine oxidoreductase activity, the intestinal superoxide production, the nitrotyrosine level, and normalized the microcirculatory dysfunction. These data demonstrate the effectiveness of GPC therapies and provide indirect evidence that the anti-inflammatory effects of PC could be linked to a reaction involving the polar part of the molecule.