Rotenone,a mitochondrial electron transport inhibitor,ameliorates ischemia–reperfusion-induced intestinal mucosal damage in rats

Abstract

In ischemia–reperfusion (I/R)-induced tissue injury, oxygen radicals can be generated by several mechanisms. One of the important sources of oxygen radicals is thought to be mitochondrial respiration. The aim of this study was to investigate the antioxidative defense effect of the mitochondrial electron transport inhibitor, rotenone using the I/R-induced rat intestinal mucosal injury model in vivo. Intestinal ischemia was induced for 30 min by applying a small clamp to the superior mesenteric artery in rats. Rotenone at a dose of 100 mg/kg was given to rats orally 2 h before the ischemia. Intraluminal hemoglobin and protein levels, the mucosal content of thiobarbituric acid-reactive substances (TBARS), the mucosal myeloperoxidase activity, and the content of inflammatory cytokines (CINC-1, TNF-α) were all significantly increased from mean basal levels after 60 min of reperfusion. These increases after I/R were inhibited by treatment with rotenone at a dose of 100 mg/kg. Co-administration with succinate (100 mg/kg), a substrate of the mitochondrial electron transport system, cancelled significant reduction of intraluminal hemoglobin and mucosal TBARS treated with rotenone alone. The results of the present study indicate that rotenone inhibited lipid peroxidation and reduced development of the intestinal mucosal inflammation induced by I/R in rats. This investigation suggests that rotenone has potential as a new therapeutic agent for reperfusion injury.     

A specific peroxisome proliferator-activated receptor-gamma (PPAR-gamma) ligand,pioglitazone, ameliorates gastric mucosal damage induced by ischemia and reperfusion in rats

Peroxisome proliferator-activated receptor-gamma (PPAR-gamma), a member of the nuclear hormone receptor superfamily, has recently been implicated as a regulator of cellular proliferation and inflammatory responses. The aim of the present study was to investigate the effects of pioglitazone on ischemia-reperfusion (I/R)-induced gastric mucosal injury in rats. Gastric ischemia was induced for 30 min by applying a small vascular clamp to the celiac artery and reperfusion was produced by removal of the clamp in male Sprague-Dawley rats treated with and without pioglitazone. Pioglitazone was given to the rats intraperitoneally 2 h before the vascular clamping. The area of gastric mucosal erosion (erosion index) significantly increased from mean basal levels after 60 min of reperfusion. This erosion index was significantly inhibited by pretreatment with pioglitazone in a dose-dependent manner. The concentration of thiobarbituric acid reactive substances (TBARS) and myeloperoxidase (MPO) activity in the gastric mucosa were both significantly increased after I/R, and pretreatment with pioglitazone significantly reduced these increases. The contents of both mucosal TNF-alpha and CINC-2beta in the I/R group were significantly increased compared with the levels in the sham-operated group. These increases in TNF-alpha and CINC-2beta were significantly inhibited by pretreatment with pioglitazone at a dose of 10 mg/kg. The results of the present study indicate that pioglitazone inhibited lipid peroxidation and reduced development of the gastric mucosal inflammation induced by I/R in rats. This investigation suggests that pioglitazone has potential as a new therapeutic agent for reperfusion injury.     

Oxygen free radical induced damage during intestinal ischemia/reperfusion in normal and xanthine oxidase deficient rats

This study looks at the role of xanthine oxidase (XO) in ischemia/reperfusion (I/R) induced intestinal mucosal damage using normal and xanthine oxidase deficient rats. Tungstate feeding for 3 days depleted the intestinal mucosal XO by 80%. A ligated loop of the rat small intestine (both normal and XO-deficient) was subjected to 1 h of total ischemia followed by 5 min revascularisation. The ensuing mucosal damage was assessed by biochemical and histological studies. Ischemia or I/R increased the XO levels in normal rats without any change in XO-deficient rats. Myeloperoxidase (a neutrophil marker) level was increased in both group of rats but it was comparatively higher in the XO-deficient rats. Accumulation of peroxidation products such as malondialdehyde, conjugated diene and increased production of hydroxyl radicals by microsomes were seen after ischemia and I/R and were similar in normal and XO-deficient rats. Studies on other parameters of peroxidation showed a decrease in polyunsaturated fatty acids and alpha-tocopherol, an increase in cysteine and cystine levels after I/R and were similar in both normal and XO-deficient rats. Histological results indicated gross morphological changes in the intestinal mucosa due to ischemia and I/R, and the damage was more severe in XO-deficient rats. These observations suggest that oxygen-derived free radicals are involved in the intestinal mucosal damage during I/R and infiltrated neutrophils rather than XO may be the primary source of free radicals under these conditions.     

The role of curcumin on intestinal oxidative stress,cell proliferation and apoptosis after ischemia/reperfusion injury in rats

The aim of this study was to demonstrate the role of curcumin on oxidative stress, cell proliferation and apoptosis in the rat intestinal mucosa after ischemia/reperfusion (I/R). A total of 30 male Wistar albino rats were divided into three groups: sham, I/R and I/R+ curcumin; each group contain 10 animals. Sham group animals underwent laparotomy without I/R injury. After I/R groups animals underwent laparotomy, 1 h of superior mesenteric artery ligation were followed by 1 h of reperfusion. In the curcumin group, 3 days before I/R, curcumin (100 mg/kg) was administered by gastric gavage. All animals were sacrificed at the end of reperfusion and intestinal tissues samples were obtained for biochemical and histopathological investigation in all groups. Curcumin treatment significantly decreased the elevated tissue malondialdehyde levels and increased of reduced superoxide dismutase, and glutathione peroxidase enzyme activities in intestinal tissues samples. I/R caused severe histopathological injury including mucosal erosions and villous congestion and hemorrhage. Curcumin treatment significantly attenuated the severity of intestinal I/R injury, with inhibiting of I/R-induced apoptosis and cell proliferation. These results suggest that curcumin treatment has a protective effect against intestinal damage induced by intestinal I/R. This protective effect is possibly due to its ability to inhibit I/R-induced oxidative stress, apoptosis and cell proliferation.     

A novel potent inhibitor of inducible nitric oxide inhibitor, ONO-1714, reduces intestinal ischemia-reperfusion injury in rats.

The overproduction of nitric oxide (NO) by inducible nitric oxide synthase (iNOS) may contribute to the pathophysiology of intestinal injury induced by ischemia-reperfusion. The aim of the present study was to examine the effect of selective iNOS inhibition by a cyclic amidine analogue, ONO-1714, on reperfusion-induced small intestinal injury and inflammation in rats. Intestinal damage was induced in male Sprague-Dawley rats by clamping both the superior mesenteric artery and the celiac trunk for 30 min, followed by reperfusion. The luminal nitrite concentration in the small intestine was measured by Griess reaction and the iNOS mRNA expression by RT-PCR. The severity of the intestinal mucosal injury and inflammation were evaluated by several biochemical markers and by the histological findings. The rats which were killed after ischemia-reperfusion had increased luminal concentrations of nitrite and iNOS mRNA expression, in addition to severe intestinal inflammation characterized by significant increases in myeloperoxidase activity, a marker of neutrophil infiltration, and by the mucosal content of CINC-1 cytokine, a neutrophil chemotactic cytokine. Administration with ONO-1714 significantly inhibited the luminal NO production. Reperfusion after 30-min ischemia resulted in an increase in luminal protein and hemoglobin concentrations, with levels reaching a maximum after 60 min of reperfusion. In contrast, pre-treatment with ONO-1714 2h before the ischemia inhibited the increases in luminal protein and hemoglobin concentration in a dose-dependent manner (0.001-0.1mg/kg). The contents of the thiobarbituric acid-reactive substances (a marker of oxidative lipid peroxidation) were significantly increased by ischemia-reperfusion, and this increase was reduced by ONO-1714. After reperfusion, the increase in tissue-associated myeloperoxidase activity, an index of neutrophil infiltration, was significantly inhibited by pre-treatment with ONO-1714. ONO-1714 also inhibited increases in intestinal CINC-1 protein and mRNA expression, as determined by ELISA and RT-PCR, respectively. In conclusion, the improvement of reperfusion-induced intestinal injury by ONO-1714 suggested that an excess of NO, produced by iNOS, may have contributed to the initiation/amplification of intestinal inflammatory injury by various mechanisms, including nitrosative and oxidative damage as well as the enhancement of inflammatory cytokine release.     

Attenuation of mitochondrial injury by L-arginine preconditioning of the liver

The present study was aimed to evaluate the efficacy of L-arginine on mitochondrial function in ischemic and reperfusion (I/R) induced hepatic injury. Adult Wistar rat were subjected to 1 h of partial liver ischemia followed by 3 hour reperfusion. Eighteen wistar rats were divided into three groups viz. sham-operated control group (I) (n = 6), ischemia and reperfusion (I/R) group (II) (n = 6), L-arginine treated group (100 mg/kg body weight/daily by oral route for 7 days before induced ischemia reperfusion maneuver) (III) (n = 6). Mitochondrial injury was assessed in terms of decreased (P < 0.05) activities of mitochondrial antioxidant enzymes (GSH, SOD, CAT), respiratory marker enzymes (NADH dehydrogenase, cytochrome c oxidases) and hepatocytes nitric oxide production. Pre-treatment with L-arginine (10 mg/kg/p.o. for 7 days) significantly counteracted the alternations of hepatic enzymes and mitochondrial respiratory and antioxidant enzymes. In addition, electron microscopy and histopathology study showed the restoration of cellular normalcy and accredits the cytoprotective role of L-arginine against I/R induced hepatocellular injury. On the basis of these findings it may be concluded that L-arginine protects mitochondrial function in hepatic ischemic and reperfused liver.     

Alda-1, an ALDH2 activator,protects against hepatic ischemia/reperfusion injury in rats via inhibition of oxidative stress

Previous studies have proved that activation of aldehyde dehydrogenase two (ALDH2) can attenuate oxidative stress through clearance of cytotoxic aldehydes, and can protect against cardiac, cerebral, and lung ischemia/reperfusion (I/R) injuries. In this study, we investigated the effects of the ALDH2 activator Alda-1 on hepatic I/R injury. Partial warm ischemia was performed in the left and middle hepatic lobes of Sprague-Dawley rats for 1?h, followed by 6?h of reperfusion. Rats received either Alda-1 or vehicle by intravenous injection 30?min before ischemia. Blood and tissue samples of the rats were collected after 6-h reperfusion. Histological injury, proinflammatory cytokines, reactive oxygen species (ROS), cellular apoptosis, ALDH2 expression and activity, 4-hydroxy-trans-2-nonenal (4-HNE) and malondialdehyde (MDA) were measured. BRL-3A hepatocytes were subjected to hypoxia/reoxygenation (H/R). Cell viability, ROS, and mitochondrial membrane potential were determined. Pretreatment with Alda-1 significantly alleviated I/R-induced elevations of alanine aminotransferase and aspartate amino transferase, and significantly blunted the pathological injury of the liver. Moreover, Alda-1 significantly inhibited ROS and proinflammatory cytokines production, 4-HNE and MDA accumulation, and apoptosis. Increased ALDH2 activity was found after Alda-1 administration. No significant changes in ALDH2 expression were observed after I/R. ROS was also higher in H/R cells than in control cells, which was aggravated upon treatment with 4-HNE, and reduced by Alda-1 treatment. Cell viability and mitochondrial membrane potential were inhibited in H/R cells, which was attenuated upon Alda-1 treatment. Activation of ALDH2 by Alda-1 attenuates hepatic I/R injury via clearance of cytotoxic aldehydes.     

RETRACTED ARTICLE: Effect of preischemic treatment with fenofibrate,a peroxisome proliferator-activated receptor-α ligand,on hepatic ischemia–reperfusion injury in rats

Liver ischemia/reperfusion (I/R) injury is a serious clinical problem. The reactive oxygen species (ROS) and tumor necrosis factor alpha (TNF-α) are important mediators in liver I/R injury. This study was designed to investigate the effect of preischemic treatment with fenofibrate (Peroxisome proliferator-activated receptor- α agonist) on the oxidative stress and inflammatory response to hepatic I/R injury in rats. Hepatic I/R was induced by clamping the blood supply of the left lateral and median lobes of the liver for 60 min, followed by reperfusion for 4 h. Each animal group was pretreated with a single dose of fenofibrate (50 mg/kg body weight) intraperitoneally 1 h before ischemia. At the end of reperfusion, blood samples and liver tissues were obtained to assess serum alanine aminotransferase (ALT), TNF-α, hepatic malondialdehyde (MDA) and superoxide dismutase activity (SOD). Liver specimens were obtained and processed for light and electron microscopic study. Hepatic I/R induced a significant elevation of serum ALT and TNF-α with significant elevation of hepatic MDA and reduction of SOD activity. Histopathological examination revealed hepatic inflammation, necrosis and apoptosis. Preischemic treatment with fenofibrate at a dose of 50 mg/kg significantly attenuated the biochemical and structural alterations of I/R-induced liver injury.     

A PPAR-gamma ligand, 15-deoxy-Delta12,14-prostaglandin J(2), inhibited gastric mucosal injury induced by ischemia-reperfusion in rats

INTRODUCTION: Recent studies have demonstrated the anti-inflammatory action of 15-deoxy-Delta12,14-prostaglandin J(2) (15d-PGJ(2)), a derivative of the PGD(2) metabolic pathway. Acute inflammation, including neutrophil activation, plays a critical role in the pathogenesis of ischemia-reperfusion (I/R). The aim of the present study was to determine the effect of 15d-PGJ(2) on I/R-induced gastric mucosal injury in rats.METHODS: Gastric mucosal damage was induced in male Wistar rats by clamping the celiac artery for 30 min followed by reperfusion. 15d-PGJ(2) (0.01-1.0 mg/kg) was given to the rats intraperitoneally 1 h before the vascular clamping. The area of gastric mucosal erosions (erosion index) was measured. Thiobarbituric acid reactive substances (TBARS) and tissue-associated myeloperoxidase (MPO) activity were measured in the gastric mucosa as indices of lipid peroxidation and neutrophil infiltration. The expression of tumor necrosis factor-alpha (TNF-alpha) in gastric mucosa was measured by ELISA. In addition, to elucidate whether the protective effects of 15d-PGJ(2) are related to the activation of the PPAR-gamma receptor, we also investigated the effects of a PPAR-gamma antagonist, GW9662.RESULTS: After 60 min of reperfusion, the area of gastric erosion index had significantly increased from the mean basal levels. The increase in the erosion index was significantly inhibited by pretreatment with 15d-PGJ(2) in a dose-dependent manner. On the other hand, GW9662 reversed the protective effect of 15d-PGJ(2). The concentration of TBARS and MPO activity in the gastric mucosa were both significantly increased after I/R, and pretreatment with 15d-PGJ(2) significantly reduced these increases. The TNF-alpha content was significantly higher in the I/R group than in the sham-operated group. However, the increase in TNF-alpha was significantly inhibited by pretreatment with 15d-PGJ(2).CONCLUSIONS: 15d-PGJ(2) significantly inhibited the severity of acute gastric mucosal injury induced by I/R in rats through PPAR-gamma-dependent mechanisms. This effect may be due, in part, to a reduction in the infiltration of neutrophils into the gastric mucosa, possibly via the inhibition of inflammatory cytokine.     

Donepezil provides neuroprotective effects against brain injury and Alzheimer's pathology under conditions of cardiac ischemia/reperfusion injury

Cardiac ischemia/reperfusion (I/R) injury induces brain pathology. Donepezil, a well-known acetylcholine esterase (AChE) inhibitor, has been proven to exert neuroprotective effects against several neurodegenerative diseases. However, the comprehensive mechanism regarding the therapeutic potential of donepezil on the brain under cardiac I/R injury remains obscure. Here, we hypothesized that treatment with donepezil ameliorates brain pathology following cardiac I/R injury by decreasing blood brain barrier (BBB) breakdown, oxidative stress, neuroinflammation, mitochondrial dysfunction, mitochondrial dynamics imbalance, microglial activation, amyloid-beta (Aβ) accumulation, neuronal apoptosis, and dendritic spine loss. Forty-eight adult male Wistar rats were subjected to surgery for cardiac I/R injury. Then, rats were randomly divided into four groups to receive either (1) saline (vehicle group), donepezil 3 mg/kg via intravenously administered (2) before ischemia (pretreatment group), (3) during ischemia (ischemia group), or (4) at the onset of reperfusion (reperfusion group). At the end of cardiac I/R paradigm, the brains were evaluated for BBB breakdown, brain inflammation, oxidative stress, mitochondrial function, mitochondrial dynamics, microglial morphology, Aβ production, neuronal apoptosis, and dendritic spine density. Administration of donepezil at all time points equally showed an attenuation of brain damage in response to cardiac I/R injury, as indicated by increased expression of BBB junction protein, reduced brain inflammation and oxidative stress, improved mitochondrial function and mitochondrial dynamics, and alleviated Aβ accumulation and microglial activation, resulting in protection of neuronal apoptosis and preservation of dendritic spine number. These findings suggest that donepezil potentially protects brain pathology caused by cardiac I/R injury regardless the timing of treatment.     

Oxygen free radical-induced damage during colonic ischemia/reperfusion in rats

Reperfusion injury following ischemia is thought to be the consequence of reactive oxygen species. Role of these free radicals on the damaging effects of ischemia in colon has been investigated. A rat experimental model was used in which colon was subjected to ischemia and reperfusion and mucosal damage was assessed by biochemical and histological studies. Activity of myeloperoxidase, a neutrophil marker, was increased after ischemia (I) and ischemia/Reperfusion (I/R). Lipid peroxidation products such as malonaldehyde and conjugated diene did not show any change in the experimental colonic mucosa as compared to control. Mucosal level of low molecular weight thiols were found to be altered after I/R. A decrease in -tocopherol level was noticed after ischemia and the decrease was prominent after reperfusion. Histology indicated morphological changes in colon due to ischemia and reperfusion and the damage was more severe after reperfusion. These results suggest that colonic mucosal damage occurs during I/R and free radicals generated by the infiltrated neutrophils may play a role in this damaging process.     

7,8-dihydroxyflavone,a small-molecule tropomyosin-related kinase B (TrkB) agonist,attenuates cerebral ischemia and reperfusion injury in rats

7,8-dihydroxyflavone (7,8-DHF) is a recently identified potent agonist of tropomyosin-related kinase B that can cross the blood–brain barrier after oral or intraperitoneal administration. The aim of the present study was to determine whether 7,8-DHF has neuroprotective effects against cerebral ischemia and reperfusion (I/R) injury and, if so, to investigate the possible underlying mechanisms. Cerebral I/R injury rats were induced by middle cerebral artery occlusion for 90 min followed by reperfusion for 24 h. 7,8-DHF was administered intraperitoneally at a dose of 5 mg/kg immediately after ischemia. Our results showed that 7,8-DHF significantly reduced neurological deficit scores, infarct volumes, and neuronal apoptosis in brains of I/R rats. Meanwhile, 7,8-DHF also increased Bcl-2 expression, decreased expression of cleaved caspase-3, Bax and inducible nitric oxide synthase, and inhibited nuclear factor-κB activation in ischemic cortex. Finally, malondialdehyde and nitric oxide contents were reduced, but activities of glutathione, glutathione peroxidase and superoxide dismutase were restored in ischemic cortex treated with 7,8-DHF. Taken together, our findings demonstrated that 7,8-DHF is able to protect against cerebral I/R injury, which may be, at least in part, attributable to its anti-apoptotic, anti-oxidative and anti-inflammatory actions.     

Hydrogen-rich saline reduces lung injury induced by intestinal ischemia/reperfusion in rats

Objective. Hydrogen has been reported to selectively reduce the hydroxyl radical, the most cytotoxic of reactive oxygen species. In this study we investigated the effects of hydrogen-rich saline on the prevention of lung injury induced by intestinal ischemia/reperfusion (I/R) in rats. Methods. Male Sprague-Dawley rats (n = 30, 200-220 g) were divided randomly into three experimental groups: sham operated, intestinal I/R plus saline treatment (5 ml/kg, i.v.), and intestinal I/R plus hydrogen-rich saline treatment (5 ml/kg, i.v.) groups. Intestinal I/R was produced by 90 min of intestinal ischemia followed by a 4 h of reperfusion. Results. Hydrogen-rich saline treatment decreased the neutrophil infiltration, the lipid membrane peroxidation, NF-κB activation and the pro-inflammatory cytokine interleukin IL-1β and TNF-α in the lung tissues compared with those in saline-treated rat. Conclusion. Hydrogen-rich saline attenuates lung injury induced by intestinal I/R.     

Attenuation of intestinal ischemia/reperfusion injury with sodium nitroprusside: studies on mitochondrial function and lipid changes

Reactive oxygen species have been implicated in cellular injury during ischemia/reperfusion (I/R). Mitochondria are one of the main targets of oxygen free radicals and damage to this organelle leads to cell death. Reports suggest that nitric oxide (NO) may offer protection from damage during I/R. This study has looked at the functional changes and lipid alteration to mitochondria during intestinal I/R and the protection offered by NO. It was observed that I/R of the intestine is associated with functional alterations in the mitochondria as suggested by MTT reduction, respiratory control ratio and mitochondrial swelling. Mitochondrial lipid changes suggestive of activation of phospholipase A(2) and phospholipase D were also seen after (I/R) mediated injury. These changes were prevented by the simultaneous presence of a NO donor in the lumen of the intestine. These studies have suggested that structural and functional alterations of mitochondria are prominent features of I/R injury to the intestine which can be ameliorated by NO.     

The effect of antioxidant supplementation on bacterial translocation after intestinal ischemia and reperfusion

The intestine is highly sensitive to ischemia/reperfusion (I/R) injury. Intestinal I/R may cause local tissue injury and disruption of the intestinal mucosal barrier, allowing the passage of viable bacteria and endotoxins from the gastrointestinal lumen to distant organs. This phenomenon, known as bacterial translocation (BT), may lead to systemic disorders with high morbidity and mortality. Oxidative stress mediators such as reactive oxygen species, polymorphonuclear neutrophils and nitric oxide are believed to contribute to the intestinal I/R injury. Many antioxidants have shown protective effects against I/R injury of various organs. The present article provides an overview of studies investigating the effect of antioxidant supplementation on BT after intestinal I/R.     

Mitochondrial Src tyrosine kinase plays a role in the cardioprotective effect of ischemic preconditioning by modulating complex I activity and mitochondrial ROS generation

Abstract

While ischemic preconditioning (IPC) and other cardioprotective interventions have been proposed to protect the heart from ischemia/reperfusion (I/R) injury by inhibiting mitochondrial complex I activity upon reperfusion, the exact mechanism underlying the modulation of complex I activity remains elusive. This study was aimed to test the hypothesis that IPC modulates complex I activity at reperfusion by activating mitochondrial Src tyrosine kinase, and induces cardioprotection against I/R injury. Isolated rat hearts were preconditioned by three cycles of 5-min ischemia and 5-min reperfusion prior to 30-min index ischemia followed by 2 h of reperfusion. Mitochondrial Src phosphorylation (Tyr⁴¹⁶) was dramatically decreased during I/R, implying inactivation of Src tyrosine kinase by I/R. IPC increased mitochondrial Src phosphorylation upon reperfusion and this was inhibited by the selective Src tyrosine kinase inhibitor PP2. IPC's anti-infarct effect was inhibited by the selective Src tyrosine kinase inhibitor PP2. Complex I activity was significantly increased upon reperfusion, an effect that was prevented by IPC in a Src tyrosine kinase-dependent manner. In support, Src and phospho-Src were found in complex I. Furthermore, IPC prevented hypoxia/reoxygenation-induced mitochondrial reactive oxygen species (ROS) generation and cellular injury in rat cardiomyocytes, which was revoked by PP2. Finally, IPC reduced LDH release induced by both hypoxia/reoxygenation and simulated ischemia/reperfusion, an effect that was reversed by PP2 and Src siRNA. These data suggest that mitochondrial Src tyrosine kinase accounts for the inhibitory action of IPC on complex I and mitochondrial ROS generation, and thereby plays a role in the cardioprotective effect of IPC.     

Mesna (2-mercaptoethane sulfonate) prevents ischemia/reperfusion induced renal oxidative damage in rats

Reoxygenation of the ischemic tissue promotes the generation of various reactive oxygen metabolites (ROM) which are known to have deleterious effects on various cellular functions. This study was designed to determine the possible protective effect of mesna (2-Mercaptoethane Sulfonate) on renal ischemia/reperfusion (I/R) injury. Wistar albino rats were unilaterally nephrectomized, and 15 days later they were subjected to 45 min of renal pedicle occlusion followed by 6 h of reperfusion. Mesna (MESNA, 150 mg/kg, i.p.; an effective dose against I/R injury) or vehicle was administered twice, 15 min prior to ischemia and immediately before the reperfusion period. At the end of the reperfusion period, rats were killed by decapitation. Kidney samples were taken for histological examination or determination of the free radicals, renal malondialdehyde (MDA) and glutathione (GSH) levels, and myeloperoxidase (MPO) activity. Renal tissue collagen content, as a fibrosis marker was also determined. Creatinine and urea concentrations in blood were measured for the evaluation of renal function. The results demonstrated that renal I/R caused nephrotoxicity, as evidenced by increases in blood urea and creatinine levels, which was reversed by MESNA treatment. Increased free radical levels, as assessed by nitroblue-tetrazolium test were reduced with MESNA. Moreover, the decrease in GSH and increases in MDA levels, and MPO activity induced by I/R indicated that renal injury involves free radical formation. Treatment of rats with MESNA restored the reduced GSH levels while it decreased MDA levels as well as MPO activity. Increased collagen contents of the kidney tissues by I/R were reversed back to the control levels by MESNA treatment. Since MESNA administration reversed these oxidant responses, improved renal function and microscopic damage, it seems likely that MESNA protects kidney tissue against I/R induced oxidative damage.     

Hydrogen-rich saline protects against intestinal ischemia/reperfusion injury in rats

Hydrogen gas was reported to reduce reactive oxygen species and alleviate cerebral, myocardial and hepatic ischemia/reperfusion (I/R) injuries. This paper studied the effect of hydrogen-rich saline, which was easier for clinical application, on the intestinal I/R injury. Model of intestinal I/R injury was induced in male Sprague-Dawley rats. Physiological saline, hydrogen-rich saline or nitrogen-rich saline (5 ml/kg) was administered via intravenous infusion at 10 min before reperfusion, respectively. The intestine damage was detected microscopically and was assessed by Chiu score system after I/R injury. In addition, serum DAO activity, TNF-α, IL-1β and IL-6 levels, tissue MDA, protein carbonyl and MPO activity were all increased significantly by I/R injury. Hydrogen-rich saline reduced these markers and relieved morphological intestinal injury, while no significant reduction was observed in the nitrogen-rich saline-treated animals. In conclusion, hydrogen-rich saline protected the small intestine against I/R injury, possibly by reduction of inflammation and oxidative stress.     

A PPAR-γ ligand, 15-deoxy-Δ12,14-prostaglandin J2, inhibited gastric mucosal injury induced by ischemia–reperfusion in rats

Abstract

Introduction: Recent studies have demonstrated the anti-inflammatory action of 15-deoxy-Δ12,14-prostaglandin J₂ (15d-PGJ₂), a derivative of the PGD₂ metabolic pathway. Acute inflammation, including neutrophil activation, plays a critical role in the pathogenesis of ischemia–reperfusion (I/R). The aim of the present study was to determine the effect of 15d-PGJ₂ on I/R-induced gastric mucosal injury in rats.

Methods: Gastric mucosal damage was induced in male Wistar rats by clamping the celiac artery for 30 min followed by reperfusion. 15d-PGJ₂ (0.01–1.0 mg/kg) was given to the rats intraperitoneally 1 h before the vascular clamping. The area of gastric mucosal erosions (erosion index) was measured. Thiobarbituric acid reactive substances (TBARS) and tissue-associated myeloperoxidase (MPO) activity were measured in the gastric mucosa as indices of lipid peroxidation and neutrophil infiltration. The expression of tumor necrosis factor-α (TNF-α) in gastric mucosa was measured by ELISA. In addition, to elucidate whether the protective effects of 15d-PGJ₂ are related to the activation of the PPAR-γ receptor, we also investigated the effects of a PPAR-γ antagonist, GW9662.

Results: After 60 min of reperfusion, the area of gastric erosion index had significantly increased from the mean basal levels. The increase in the erosion index was significantly inhibited by pretreatment with 15d-PGJ₂ in a dose-dependent manner. On the other hand, GW9662 reversed the protective effect of 15d-PGJ₂. The concentration of TBARS and MPO activity in the gastric mucosa were both significantly increased after I/R, and pretreatment with 15d-PGJ₂ significantly reduced these increases. The TNF-α content was significantly higher in the I/R group than in the sham-operated group. However, the increase in TNF-α was significantly inhibited by pretreatment with 15d-PGJ₂.

Conclusions: 15d-PGJ₂ significantly inhibited the severity of acute gastric mucosal injury induced by I/R in rats through PPAR-γ-dependent mechanisms. This effect may be due, in part, to a reduction in the infiltration of neutrophils into the gastric mucosa, possibly via the inhibition of inflammatory cytokine.