Ethanol preconditioning protects against ischemia/reperfusion-induced brain damage: role of NADPH oxidase-derived ROS

Ethanol preconditioning (EtOH-PC) refers to a phenomenon in which tissues are protected from the deleterious effects of ischemia/reperfusion (I/R) by prior ingestion of ethanol at low to moderate levels. In this study, we tested whether prior (24 h) administration of ethanol as a single bolus that produced a peak plasma concentration of 42-46 mg/dl in gerbils would offer protective effects against neuronal damage due to cerebral I/R. In addition, we also tested whether reactive oxygen species (ROS) derived from NADPH oxidase played a role as initiators of these putative protective effects. Groups of gerbils were administered either ethanol or the same volume of water by gavage 24 h before transient global cerebral ischemia induced by occlusion of both common carotid arteries for 5 min. In some experiments, apocynin, a specific inhibitor of NADPH oxidase, was administered (5 mg/kg body wt, i.p.) 10 min before ethanol administration. EtOH-PC ameliorated behavioral deficit induced by cerebral I/R and protected the brain against I/R-induced delayed neuronal death, neuronal and dendritic degeneration, oxidative DNA damage, and glial cell activation. These beneficial effects were attenuated by apocynin treatment coincident with ethanol administration. Ethanol ingestion was associated with translocation of the NADPH oxidase subunit p67(phox) from hippocampal cytosol fraction to membrane, increased NADPH oxidase activity in hippocampus within the first hour after gavage, and increased lipid peroxidation (4-hydroxy-2-nonenal) in plasma and hippocampus within the first 2 h after gavage. These effects were also inhibited by concomitant apocynin treatment. Our data are consistent with the hypothesis that antecedent ethanol ingestion at socially relevant levels induces neuroprotective effects in I/R by a mechanism that is triggered by ROS produced through NADPH oxidase. Our results further suggest the possibility that preconditioning with other pharmacological agents that induce a mild oxidative stress may have similar therapeutic value for suppressing stroke-mediated damage in brain.     

Protective effects of taurine against renal ischemia/reperfusion injury in rats by inhibition of gelatinases,MMP-2 and MMP-9, and p38 mitogen-activated protein kinase signaling

Dysregulated expression of matrix metalloproteinases (MMPs) is closely associated with the pathogenesis of renal ischemia/reperfusion injury (I/R). The production of excessive reactive oxygen species (ROS) causes tissue damage. Increased ROS production causes activation of p38 mitogen-activated protein kinase (MAPK) signaling, which participates in gene regulation of MMPs, especially MMP-2 and MMP-9 (gelatinases). Taurine (2-aminoethanesulfonic acid) in mammalian cells functions in bile acid conjugation, maintenance of calcium homeostasis, osmoregulation, membrane stabilization, and antioxidation, antiinflammatory, and antiapoptotic action. We investigated the effects of taurine and the possible role of p38 MAPK signaling on regulation of MMP-2 and MMP-9 in a renal I/R injury model in rats. Rats were divided into three groups: sham, I/R, and I/R + taurine treated. After a right nephrectomy, I/R was induced by clamping the left renal pedicle for 1 h followed by 6 h reperfusion. Taurine was administered 45 min prior to induction of ischemia. Renal function was assessed by serum creatinine and blood urea nitrogen (BUN) levels. Tubule injury and structural changes were evaluated by light microscopy. Malondialdehyde (MDA) levels were analyzed by high performance liquid chromatography (HPLC). Superoxide dismutase (SOD) activity levels were measured using a colorimetric kit. mRNA expression of MMP-2 and MMP-9 was determined by real-time polymerase chain reaction. MMP-2 and MMP-9 activities were measured using a fluorimetric kit. Phosphorylated p38 (p-p38) and total p38 MAPK protein expressions were evaluated by western blot. Taurine pretreatment significantly attenuated renal dysfunction and histologic damage, such as renal tubule dilation and loss of brush borders. The pretreatment also decreased the MDA level and attenuated the reduction of SOD activity in the kidney during I/R. Taurine pretreatment also decreased significantly both MMP-2 and MMP-9 mRNA expression and MMP-9 activity induced by I/R. In addition, the activity of p38 MAPK signaling was down-regulated significantly by taurine administration. Inhibition of MMP-2 and MMP-9 expression and MMP-9 activity caused by taurine may be associated with suppression of p38 MAPK activation during I/R induced renal injury in rats. Therefore, taurine administration may prove to be a strategy for attenuating renal I/R injury.     

Protective effect of Urtica dioica L. on renal ischemia/reperfusion injury in rat

Renal ischemia–reperfusion (I/R) injury may occur after renal transplantation, thoracoabdominal aortic surgery, and renal artery interventions. This study was designed to investigate the effect of Urtica dioica L. (UD), in I/R induced renal injury. A total of 32 male Sprague–Dawley rats were divided into four groups: control, UD alone, I/R and I/R?+?UD; each group contain 8 animals. A rat model of renal I/R injury was induced by 45-min occlusion of the bilateral renal pedicles and 24-h reperfusion. In the UD group, 3?days before I/R, UD (2?ml/kg/day intraperitoneal) was administered by gastric gavage. All animals were sacrificed at the end of reperfusion and kidney tissues samples were obtained for histopathological investigation in all groups. To date, no more histopathological changes on intestinal I/R injury in rats by UD treatment have been reported. Renal I/R caused severe histopathological injury including tubular damage, atrophy dilatation, loss of brush border and hydropic epithelial cell degenerations, renal corpuscle atrophy, glomerular shrinkage, markedly focal mononuclear cell infiltrations in the kidney. UD treatment significantly attenuated the severity of intestinal I/R injury and significantly lowered tubulointerstitial damage score than the I/R group. The number of PCNA and TUNEL positive cells in the control and UD alone groups was negligible. When kidney sections were PCNA and TUNEL stained, there was a clear increase in the number of positive cells in the I/R group rats in the renal cortical tissues. However, there is a significant reduction in the activity of PCNA and TUNEL in kidney tissue of renal injury induced by renal I/R with UD therapy. Our results suggest that administration of UD attenuates renal I/R injury. These results suggest that UD treatment has a protective effect against renal damage induced by renal I/R. This protective effect is possibly due to its ability to inhibit I/R induced renal damage, apoptosis and cell proliferation.     

Complement plays an important role in gastric mucosal damage induced by ischemia-reperfusion in rats.

Ischemia-reperfusion (I/R) of stomach causes gastric mucosal injury. Complement can also cause tissue damage, however its role in gastric I/R injury has not been thoroughly investigated. We evaluated the effect of complement suppression in reducing damage to the gastric epithelium caused by local I/R. Local gastric ischemia was induced by clamping the left gastric artery. The blood-to-lumen clearance of 51Cr-labeled EDTA (51Cr-EDTA) served as an index of epithelial damage. 51Cr-EDTA clearance increased shortly after reperfusion with peak values at 10 min. Intraperitoneal administration of cobra venom factor (CVF; 50 units) prior to I/R, which reduced the serum complement value (CH50) to an undetectable level, remarkably suppressed the 51Cr-EDTA clearance following reperfusion. A monocarboxylic acid derivative of K-76 (K-76 COOH) reduced the CH50 by more than 30% (100 mg/kg) and 60% (200 mg/kg). Rats pretreated with K-76 significantly attenuated the increase in 51Cr-EDTA clearance produced by I/R. These results suggest that complement inhibitor could be used to protect gastric mucosal injury induced by local I/R stress.     

The role of excessive versus acute administration of erythropoietin in attenuating hepatic ischemia-reperfusion injury

Ischemia-reperfusion injury (I/R) is the main cause of primary graft nonfunction. Our aim was to evaluate the effect of excessive versus acute administration of erythropoietin (EPO) in attenuating the hepatic injury induced by I/R in mice. The effect of segmental (70%) hepatic ischemia was evaluated in a transgenic mouse line with constitutive overexpression of human EPO cDNA and in wild-type (WT) mice. Mice were randomly allocated to 5 main experimental groups: (i) WT-sham, (ii) WT ischemia, (iii) WT ischemia + recombinant human erythropoietin (rhEPO), (iv) transgenic-sham, and (v) transgenic ischemia. The EPO-pretreated mice showed a significant reduction in liver enzyme levels and intrahepatic caspase-3 activity and fewer apoptotic hepatocytes (p < 0.05 for all) compared with the WT untreated I/R group. EPO decreased c-Jun N-terminal kinase (JNK) phosphorylation and nuclear factor-κB (NF-κB) expression during I/R. In transgenic I/R livers, baseline histology showed diffused hepatic injury, and no significant beneficial effect was noted between the WT untreated and the transgenic I/R mice. In conclusion, acute pretreatment with EPO in WT mice attenuated in vivo I/R liver injury. However, in excessive EPO overexpression, the initial liver injury abolished the beneficial effect of EPO. These findings have important implications for the potential use of acute EPO in I/R injury during liver transplantation.     

AICAR Attenuates Organ Injury and Inflammatory Response after Intestinal Ischemia and Reperfusion

Intestinal ischemia and reperfusion (I/R) is encountered in various clinical conditions and contributes to multiorgan failure and mortality as high as 60% to 80%. Intestinal I/R not only injures the intestine, but affects remote organs such as the lung leading to acute lung injury. The development of novel and effective therapies for intestinal I/R are critical for the improvement of patient outcome. AICAR (5-aminoimidazole-4-carboxyamide ribonucleoside) is a cell-permeable compound that has been shown to possess antiinflammatory effects. The objective is to determine that treatment with AICAR attenuates intestinal I/R injury and subsequent acute lung injury (ALI). Male Sprague Dawley rats (275 to 325 g) underwent intestinal I/R injury with blockage of the superior mesenteric artery for 90 min and subsequent reperfusion. At the initiation of reperfusion, vehicle or AICAR (30 mg/kg BW) was given intravenously (IV) for 30 min. At 4 h after reperfusion, blood and tissues were collected for further analyses. Treatment with AICAR significantly decreased the gut damage score and the water content, indicating improvement in histological integrity. The treatment also attenuated tissue injury and proinflammatory cytokines, and reduced bacterial translocation to the gut. AICAR administration after intestinal I/R maintained lung integrity, attenuated neutrophil chemotaxis and infiltration to the lungs and decreased lung levels of tumor necrosis factor (TNF)-α and interleukin (IL)-6. Inflammatory mediators, lung-inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) proteins, were decreased in the lungs and lung apoptosis was significantly reduced after AICAR treatment. These data indicate that AICAR could be developed as an effective and novel therapeutic for intestinal I/R and subsequent ALI.     

The protective effect of oxytocin on renal ischemia/reperfusion injury in rats

AIM: Oxytocin was previously shown to have anti-inflammatory effects in different inflammation models. The major objective of the present study was to evaluate the protective role of oxytocin (OT) in protecting the kidney against ischemia/reperfusion (I/R) injury. MATERIALS AND METHODS: Male Wistar albino rats (250-300 g) were unilaterally nephrectomized, and subjected to 45 min of renal pedicle occlusion followed by 6 h of reperfusion. OT (1 mg/kg, ip) or vehicle was administered 15 min prior to ischemia and was repeated immediately before the reperfusion period. At the end of the reperfusion period, rats were decapitated and kidney samples were taken for histological examination or determination of malondialdehyde (MDA), an end product of lipid peroxidation; glutathione (GSH), a key antioxidant; and myeloperoxidase (MPO) activity, an index of tissue neutrophil infiltration. Creatinine and urea concentrations in blood were measured for the evaluation of renal function, while TNF-alpha and lactate dehydrogenase (LDH) levels were determined to evaluate generalized tissue damage. Formation of reactive oxygen species in renal tissue samples was monitored by chemiluminescence technique using luminol and lucigenin probes. RESULTS: The results revealed that I/R injury increased (p<0.01-0.001) serum urea, creatinine, TNF-alpha and LDH levels, as well as MDA, MPO and reactive oxygen radical levels in the renal tissue, while decreasing renal GSH content. However, alterations in these biochemical and histopathological indices due to I/R injury were attenuated by OT treatment (p<0.05-0.001). CONCLUSIONS: Since OT administration improved renal function and microscopic damage, along with the alleviation of oxidant tissue responses, it appears that oxytocin protects renal tissue against I/R-induced oxidative damage.     

Plumbagin inhibits neuronal apoptosis,intimal hyperplasia and also suppresses TNF-α/NF-κB pathway induced inflammation and matrix metalloproteinase-2/9 expression in rat cerebral ischemia

Cerebral ischemic damage and infarction are well documented in stroke, which is presenting a foremost health concern globally with very high mortality and morbidity rates. Mechanisms that are associated with excitotoxicity, inflammation and oxidative stress are found to be critically involved in ischemic damage. Adverse effects of current therapies are imposing the need in development of neuroprotective agents that are very effective. To explore this we experimentally induced ischemic brain injury and investigated the effects of plumbagin. Induction of cerebral infarction and ischemia-reperfusion (I/R) was done by middle cerebral artery occlusion (MCAO) in Sprague-Dawley rats. Plumbagin (50, 100 or 200 mg/kg b.wt) was intragastrically administered for 9 days before ischemia induction and an hour prior on the day of ischemic insult. Plumbagin treatment attenuated pulmonary edema, neuronal apoptosis and reduced cerebral infarct volume. Cleaved caspase-3 and apoptotic cascade protein expressions were regulated. Overproduction of pro-inflammatory cytokines (TNF-α, IL-1β and IL-6) and nitric oxide (NO) following I/R were reduced. Prior plumbagin administration had down-regulated NF-κB signalling and MMP-2 and MMP-9 expression. Overall, the results reveal the potent neuroprotective efficacy of plumbagin against I/R-induced brain injury via effectively modulating apoptotic pathways, MMPs and neuro-inflammatory cascades.     

Live attenuated Salmonella carrying platelet factor 4 cDNAs as radioprotectors

To determine whether live attenuated Salmonella carrying platelet factor 4 cDNAs can protect mice from radiation damage, the attenuated Salmonella SL3261 was used as oral vector for targeted gene delivery. The recovery of mice receiving sublethal total-body irradiation (TBI) was investigated after the oral administration of attenuated Salmonella carrying cDNA for platelet factor 4 (PF4) or truncated PF4. This oral gene therapy protected mice from radiation damage after TBI. The number of bone marrow cells and high proliferative potential colony-forming cells (HPP-CFCs) increased significantly at day 7. Similarly, the administration of PF4 or PF4(17-70) protein also improved the survival of mice after TBI. Both PF4 gene therapy and protein administration accelerated hematopoietic recovery in vivo in mice after irradiation. In vitro, PF4 also promoted survival and proliferation of 5-fluorouracil-resistant hematopoietic stem/progenitor cells after irradiation. These data demonstrate a novel biological function of PF4 as a protector against radiation injury and suggest that attenuated Salmonella could be used in vivo as a PF4 DNA delivery vector in the management of radiation injury.     

Measurement of intracellular biomolecular oxidation in liver ischemia-reperfusion injury via immuno-spin trapping

Hepatic ischemia-reperfusion (I/R) can lead to liver failure in association with remote organ damage, both of which have significant rates of morbidity and mortality. In this study, novel spin trapping and histopathological techniques have been used to investigate in vivo free radical formation in a rat model of warm liver I/R injury. 5,5-Dimethyl-1-pyrroline N-oxide (DMPO) was administered to rats via intraperitoneal injection at a single dose of 1.5g of pure DMPO/kg body wt 2h before the initiation of liver ischemia. Blood vessels supplying the median and left lateral hepatic lobes were occluded with an arterial clamp for 60min, followed by 60min reperfusion. The effects of DMPO on I/R injury were evaluated by assessing the hepatic ultrastructure via transmission electron microscopy and by histopathological scoring. Immunoelectron microscopy was performed to determine the cellular localization of DMPO nitrone adducts. Levels of nitrone adducts were also measured to determine in situ scavenging of protein and DNA radicals. Total histopathological scoring of cellular damage was significantly decreased in hepatic I/R injury after DMPO treatment. DMPO treatment significantly decreased the hepatic conversion of xanthine oxidase and 4-hydroxynonenal formation in I/R injury compared to the untreated I/R group. The distribution of gold-nanoparticle-labeled DMPO nitrone adducts was observed in mitochondria, cytoplasm, and nucleus of hepatocytes. The formation of protein- and DNA-nitrone adducts was increased in DMPO-treated I/R livers compared to DMPO controls, indicating increased in situ protein and DNA radical formation and scavenging by DMPO. These results suggest that DMPO reduces I/R damage via protection against oxidative injury.     

Protective effects of chlorogenic acid against ischemia/reperfusion injury in rat liver: molecular evidence of its antioxidant and anti-inflammatory properties

Hepatic ischemia and reperfusion injury (I/R) is accompanied by excessive reactive oxygen species and resultant sterile inflammation. Chlorogenic acid (CGA), one of the most abundant polyphenols in the human diet, has been shown to exert potent anti-inflammatory, antibacterial and antioxidant activities. Thus, the purpose of the present study was to investigate protective effects of CGA and its molecular mechanisms against hepatic I/R injury. Rats were subjected to 60 min of partial hepatic ischemia followed by 5 h of reperfusion. CGA (2.5, 5 and 10 mg/kg, ip) was administered twice: 10 min prior to ischemia and 10 min before reperfusion. CGA treatment resulted in marked improvement of hepatic function and histology, and suppressed oxidative stress, as indicated by hepatic lipid peroxidation and glutathione level. Levels of serum tumor necrosis factor-α, inducible nitric oxide synthase and cyclooxygenase-2 protein and mRNA expressions were up-regulated after I/R; these effects were attenuated by CGA. Immunoblot results showed that CGA reduced I/R-induced toll-like receptor 4 overexpression, nuclear translocation of nuclear factor kappa B and interferon regulatory factor-1, high-mobility group box-1 release into extracellular milieu, and enhanced heme oxygenase-1 expression and nuclear translocation of nuclear factor erythroid 2-related factor 2. Our results suggest that CGA alleviates I/R-induced liver injury and that this protection is likely due to inhibition of inflammatory response and enhancement of antioxidant defense systems. Therefore, CGA might have potential as an agent for use in clinical treatment of hepatic I/R injury.     

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.     

Bcl-xL gene transfer protects the heart against ischemia/reperfusion injury

Ischemia and reperfusion (I/R) injury causes the progression of cardiac dysfunction. The prevention of cardiomyocyte-loss due to I/R injury is important for the treatment of heart failure. Therefore, we employed antiapoptotic Bcl-xL protein to prevent I/R injury in the heart and evaluated the cardioprotective effect of Bcl-xL transduction by adenoviral vector (Adv) after I/R injury. Adv with Bcl-xL gene was injected in the rat heart 4 days prior to I/R. The prevention of cardiac performance-loss and the reduction of cardiac apoptosis, after 30min ischemia and 30min reperfusion of global I/R, were demonstrated in the heart with adenoviral Bcl-xL transduction. Also, significant reductions of the infarct size and serum creatine kinase levels were observed in the heart transduced with Bcl-xL gene compared with control after 30min ischemia and 24h reperfusion of the left anterior coronary artery. Thus, Bcl-xL may serve as a potential therapeutic tool for cardioprotection.     

Oral administration of Antioxidant Biofactor (AOBtrade mark) ameliorates ischemia/reperfusion- induced neuronal death in the gerbil

Oxidative damage due to ischemia/reperfusion has been implicated as one of the leading causes for delayed neuronal cell death in a number of neurodegenerative diseases, including stroke. The purpose of this research was to investigate whether oral administration of a fermented grain food mixture (AOB(R)) might offer protective effects against ischemia/reperfusion-induced neuronal damage in Mongolian gerbils, a model known for delayed neuronal death in the hippocampal CA1 region. Histological analysis revealed that AOB administration ad libitum for 3 weeks (preoperative administration) and 1 week (postoperative administration) dose-dependently suppressed the induction of transient ischemia/reperfusion-induced neuronal cell death. TUNEL assay also revealed that AOB suppressed it by inhibiting the induction of apoptosis. A significant increase of superoxide dismutase-like (SOD-like) activity was observed in the hippocampal CA1 region of the AOB-treated gerbil. Furthermore, immunoblot analysis showed that AOB administration down-regulated the expression of heat shock proteins HSP27 and HSP70 in the same region. These results indicated that oral administration of AOB protected against ischemia/reperfusion-induced brain injury by minimizing oxidative damage via its SOD-like activity and inhibiting apoptosis.     

Orexigenic hormone ghrelin attenuates local and remote organ injury after intestinal ischemia-reperfusion

Background

Gut ischemia/reperfusion (I/R) injury is a serious condition in intensive care patients. Activation of immune cells adjacent to the huge endothelial cell surface area of the intestinal microvasculature produces initially local and then systemic inflammatory responses. Stimulation of the vagus nerve can rapidly attenuate systemic inflammatory responses through inhibiting the activation of macrophages and endothelial cells. Ghrelin, a novel orexigenic hormone, is produced predominately in the gastrointestinal system. Ghrelin receptors are expressed at a high density in the dorsal vagal complex of the brain stem. In this study, we investigated the regulation of the cholinergic anti-inflammatory pathway by the novel gastrointestinal hormone, ghrelin, after gut I/R.

Methods and Findings

Gut ischemia was induced by placing a microvascular clip across the superior mesenteric artery for 90 min in male adult rats. Our results showed that ghrelin levels were significantly reduced after gut I/R and that ghrelin administration inhibited pro-inflammatory cytokine release, reduced neutrophil infiltration, ameliorated intestinal barrier dysfunction, attenuated organ injury, and improved survival after gut I/R. Administration of a specific ghrelin receptor antagonist worsened gut I/R-induced organ injury and mortality. To determine whether ghrelin''s beneficial effects after gut I/R require the intact vagus nerve, vagotomy was performed in sham and gut I/R animals immediately prior to the induction of gut ischemia. Our result showed that vagotomy completely eliminated ghrelin''s beneficial effect after gut I/R. To further confirm that ghrelin''s beneficial effects after gut I/R are mediated through the central nervous system, intracerebroventricular administration of ghrelin was performed at the beginning of reperfusion after 90-min gut ischemia. Our result showed that intracerebroventricular injection of ghrelin also protected the rats from gut I/R injury.

Conclusions

These findings suggest that ghrelin attenuates excessive inflammation and reduces organ injury after gut I/R through activation of the cholinergic anti-inflammatory pathway.     

Therapeutic administration of IL-11 exhibits the postconditioning effects against ischemia-reperfusion injury via STAT3 in the heart

Activation of cardiac STAT3 by IL-6 cytokine family contributes to cardioprotection. Previously, we demonstrated that IL-11, an IL-6 cytokine family, has the therapeutic potential to prevent adverse cardiac remodeling after myocardial infarction; however, it remains to be elucidated whether IL-11 exhibits postconditioning effects. To address the possibility that IL-11 treatment improves clinical outcome of recanalization therapy against acute myocardial infarction, we examined its postconditioning effects on ischemia/reperfusion (I/R) injury. C57BL/6 mice were exposed to ischemia (30 min) and reperfusion (24 h), and IL-11 was intravenously administered at the start of reperfusion. I/R injury mediated the activation of STAT3, which was enhanced by IL-11 administration. IL-11 treatment reduced I/R injury, analyzed by triphenyl tetrazolium chloride staining [PBS, 46.7 ± 14.4%; IL-11 (20 μg/kg), 28.6 ± 7.5% in the ratio of infarct to risk area]. Moreover, echocardiographic and hemodynamic analyses clarified that IL-11 treatment preserved cardiac function after I/R. Terminal deoxynucleotide transferase-mediated dUTP nick-end labeling staining revealed that IL-11 reduced the frequency of apoptotic cardiomyocytes after I/R. Interestingly, IL-11 reduced superoxide production assessed by in situ dihydroethidium fluorescence analysis, accompanied by the increased expression of metallothionein 1 and 2, reactive oxygen species (ROS) scavengers. Importantly, with the use of cardiac-specific STAT3 conditional knockout (STAT3 CKO) mice, it was revealed that cardiac-specific ablation of STAT3 abrogated IL-11-mediated attenuation of I/R injury. Finally, IL-11 failed to suppress the ROS production after I/R in STAT3 CKO mice. IL-11 administration exhibits the postconditioning effects through cardiac STAT3 activation, suggesting that IL-11 has the clinical therapeutic potential to prevent I/R injury in heart.     

Protective effects of oral administration of yeast thioredoxin against gastric mucosal injury

Thioredoxin (TRX) is a redox regulating protein which has protective effects against oxidative stress-induced damage to cells and tissues. In this study, we investigated the effects of orally administered TRX derived from edible yeast, Saccharomyces cerevisiae, on gastric mucosa. First, we examined the digestibility of orally administered yeast TRX in mice, and detected yeast TRX in the stomach for 4?h after administration. Next, we investigated the mitigation of gastric mucosal injury after the oral administration of yeast TRX in water-immersion restraint stress and HCl/ethanol-induced gastric ulcer models. Furthermore, we conducted DNA microarray analysis, using the HCl/ethanol-induced model, which revealed that several groups of genes related to tissue repair were upregulated in ulcer regions in the stomachs of rats administered with yeast TRX. These results demonstrated the viability of the use of oral administrations of yeast TRX to protect the gastric mucosa.     

Effect of tocilizumab on ischemia-reperfusion-induced oxido-inflammatory renal damage and dysfunction in rats

Ischemia-reperfusion-induced (I/R) renal damage is a pathogenic process that starts with ischemia, then progresses through oxidative stress and inflammation. Tocilizumab (TCZ), a recombinant human monoclonal antibody produced against the IL-6 receptor, will be tested against renal I/R injury. TCZ is known to lower the levels of proinflammatory cytokines and oxidant mediators while raising the amounts of antioxidant molecules. Our purpose is to evaluate the biochemical and histological effects of TCZ against I/R-induced oxido-inflammatory kidney damage and dysfunction in rats. Animals were divided into 3 groups as renal I/R (RIR), I/R+ TCZ (IRT), and healthy group (HG). TCZ was administered at a dose of 8 mg/kg to the IRT group (n=6) of the animals, and distilled water as a solvent was administered intraperitoneally (ip) to the RIR (n=6) and HG (n=6) groups. Then, two hours of ischemia and six hours of reperfusion were applied to the left kidneys of IRT and RIR animals. TCZ significantly inhibited the increase in the levels of malondialdehyde (MDA), nuclear kappa B (NF-κB), tumour necrosis factor alpha (TNF-α), interleukin 1-β (IL-1β), IL-6, creatinine (Cr) and blood urea nitrogen (BUN) and decrease in total glutathione (tGSH) with I/R in renal tissue. TCZ also attenuated severe histopathological damage due to I/R in renal tissue. TCZ protected renal tissue from I/R-induced oxidative and inflammatory damage. These results indicate that TCZ may be useful in the treatment of renal I/R injury.     

多巴胺D1和D2受体激动剂和拮抗剂对脑缺血/再灌注损伤的影响

实验应用开阔法、组织病理学方法、原位末端标记(in situ terminal deoxynucleotidyl transferase-metliated de-oxy-UTP mick end labeling,TUNEL)法及免疫组织化学等方法,探讨多巴胺D1、D2受体激动剂和拮抗剂对沙土鼠前脑缺血／再灌注损伤海马CA1区神经元凋亡及凋亡相关基因bcl-2、bax表达的影响。结果显示：前脑缺血5min可引起沙土鼠探索活动增加;再灌注3d,海马CA1区约95％的锥体细胞凋亡;再灌注7d,海马CA1区仅残存约2％—7％的存活锥体细胞;前脑缺血5min可抑制bcl-2的表达并诱导bax表达增高;预先应用D2受体激动剂培高利特可减轻缺血后沙土鼠行为学异常、抑制海马CA1区锥体细胞凋亡、提高锥体细胞存活数、显著诱导bcl-2的表达并抑制bax的表达。预先应用SKF38393、SCH23390及螺哌隆对以上结果无明显影响。实验结果提示,培高利特具有确切的脑保护作用,诱导bcl-2并抑制bax的表达可能是其脑保护作用机制之一。     

The protective effect of niacinamide on ischemia-reperfusion-induced liver injury

Reperfusion of ischemic liver results in the generation of oxygen radicals, nitric oxide (NO) and their reaction product peroxynitrite, all of which may cause strand breaks in DNA, which activate the nuclear enzyme poly(ADP ribose)synthase (PARS). This results in rapid depletion of intracellular nicotinamide adenine dinucleotide and adenosine 5'-triphosphate (ATP) and eventually induces irreversible cytotoxicity. In this study, we demonstrated that niacinamide, a PARS inhibitor, attenuated ischemia/reperfusion (I/R)-induced liver injury. Ischemia was induced by clamping the common hepatic artery and portal vein of rats for 40 min. Thereafter, flow was restored and the liver was reperfused for 90 min. Blood samples collected prior to I and after R were analyzed for methyl guanidine (MG), NO, tumor necrosis factor (TNF-alpha) and ATP. Blood levels of aspartate transferase (AST), alanine transferase (ALT) and lactate dehydrogenase (LDH) which served as indexes of liver injury were measured. This protocol resulted in elevation of the blood NO level (p < 0.01). Inflammation was apparent, as TNF-alpha and MG levels were significantly increased (p < 0.05 and p < 0.001). AST, ALT and LDH were elevated 4- to 5-fold (p < 0.001), while ATP was significantly diminished (p < 0.01). After administration of niacinamide (10 mM), liver injury was significantly attenuated, while blood ATP content was reversed. In addition, MG, TNF-alpha and NO release was attenuated. These results indicate that niacinamide, presumably by acting with multiple functions, exerts potent anti-inflammatory effects in I/R-induced liver injury.