Early elimination of uremic toxin ameliorates AKI-to-CKD transition.

Acute kidney injury (AKI)-related fibrosis is emerging as a major driver of chronic kidney disease (CKD) development. Aberrant kidney recovery after AKI is multifactorial and still poorly understood. The accumulation of indoxyl sulfate (IS), a protein-bound uremic toxin, has been identified as a detrimental factor of renal fibrosis. However, the mechanisms underlying IS-related aberrant kidney recovery after AKI is still unknown. The present study aims to elucidate the effects of IS on tubular damage and its involvement in the pathogenesis of AKI-to-CKD transition. Our results showed that serum IS started to accumulate associated with the downregulation of tubular organic anion transporter but not observed in the small-molecule uremic toxins of the unilateral ischemia-reperfusion injury (UIRI) without a contralateral nephrectomy model. Serum IS is positively correlated with renal fibrosis and binding immunoglobulin protein (BiP) and CAAT/enhancer-binding protein (C/EBP) homologous protein (CHOP) expression induction in the UIRI with a contralateral nephrectomy model (UIRI+Nx). To evaluate the effects of IS in the AKI-to-CKD transition, we administered indole, a precursor of IS, at the early stage of UIRI. Our results demonstrated IS potentiates renal fibrosis, senescence-associated secretory phenotype (SASP), and activation of endoplasmic reticulum (ER) stress, which is attenuated by synergistic AST-120 administration. Furthermore, we clearly demonstrated that IS exposure potentiated hypoxia-reperfusion (H/R) induced G2/M cell cycle arrest, epithelial-mesenchymal transition (EMT) and aggravated ER stress induction in vitro. Finally, the ER chemical chaperon, 4-phenylbutyric acid (4-PBA), successfully reversed the above-mentioned AKI-to-CKD transition. Taken together, early IS elimination in the early stage of AKI is likely to be a useful strategy in the prevention and/or treatment of the AKI-to-CKD transition.

PK-PD Correlation of Erigeron Breviscapus Injection in the Treatment of Cerebral Ischemia-Reperfusion Injury Model Rats.

By measuring the cerebral infarction rate and neurological behavioral score of rats in a sham operation group, an MCAO model control group and an Erigeron breviscapus injection treatment group, we explored the therapeutic effects of Erigeron breviscapus injection on brain tissue and neuroethological injury in rats. Plasma samples were collected at 18 time points after intravenous injection of Erigeron breviscapus. The levels of scutellarin, 4-caffeoylquinic acid, 5-caffeoylquinic acid, 3,5-dicaffeoylquinic acid, 4,5-dicaffeoylquinic acid, chlorogenic acid and isochlorogenic acid B in rat plasma at the various time points were determined by an HPLC method, and drug concentration versus time plots were constructed to estimate the pharmacokinetic parameters. Finally, a PK-PD combined model was used to analyze the relationship between the blood concentration, time and therapeutic effects of the seven active components. The results of the pharmacodynamics studies showed that the cerebral infarction rate of rats in the Erigeron breviscapus injection group decreased significantly at 5 min, 10 min, 20 min, 6 h, 8 h, 18 h, 24 h, 32 h, 40 h and 48 h after cerebral ischemia. Abnormal neurological behavior scores were significantly reduced after 4 h of cerebral ischemia. The pharmacokinetics results showed that the seven chemical constituents in Erigeron breviscapus injection reached their highest detection value after 5 min of cerebral ischemia. The lowest detection values of scutellarin and isochlorogenic acid B appeared after 6 h of cerebral ischemia but could not be detected after 8 h. The lowest detection values of 5-caffeoylquinic acid and 4,5-dicaffeoylquinic acid were found in the third hour of cerebral ischemia but not after 4 h. The lowest detection values of 4-caffeoylquinic acid, 3,5-dicaffeoylquinic acid and chlorogenic acid were found during the second hour of cerebral ischemia but not at the third hour. However, at 18 h, 24 h, 32 h and 40 h of cerebral ischemia, the cerebral infarction rates of rats in the Erigeron breviscapus injection group were significantly reduced, with decreased values of 6.22%, 11.71%, 6.92% and 4.96%, respectively, and the effects were stronger than those after 5-20 min of cerebral ischemia. The decreased values reached their highest value after 24 h of cerebral ischemia. Our results show that the effects of Erigeron breviscapus injection on reducing the cerebral infarct rate in MCAO model rats are characterized by a fast onset and long maintenance time. The 5-min blood concentration in cerebral ischemia was the highest test value, and after this time, the cerebral infarction rate of MCAO rats began to decrease. However, the peak value of the effects lagged behind that of the plasma concentration. The maximum effective time for Erigeron breviscapus injection appeared 24 h after cerebral ischemia, which provides a reference for the screening of specific drugs for ischemic stroke, optimal dosing regimens and rational clinical drug use. Graphical Abstract.

Anti-inflammatory and antioxidant activity of essential amino acid α-ketoacid analogues against renal ischemia-reperfusion damage in Wistar rats. / Actividad antiinflamatoria y antioxidante de los α-cetoanálogos de aminoácidos esenciales en un modelo de daño por isquemia-reperfusión en ratas Wistar

INTRODUCTION: Essential amino acid α-keto acid analogs are used in the treatment of chronic kidney disease to delay the symptoms of uremia. However, it is unknown whether essential amino acid α-keto acid analogs affect the oxidative stress and the inflammation in acute renal injury such as those produced by ischemia-reperfusion. OBJECTIVE: To evaluate the effect of essential amino acid α-keto acid analogs on renal ischemia-reperfusion injury in Wistar rats. MATERIALS AND METHODS: Rats were divided into 11 groups (n=6/group): Two groups received physiological saline with or without ischemia-reperfusion injury (45 min/24 h), six groups received essential amino acid α-keto acid analogs (400, 800, or 1,200 mg/kg/24 h/7d) with or without ischemia-reperfusion injury (essential amino acid α-keto acid analogs + ischemia-reperfusion), and two groups received allopurinol (50 mg/kg/24 h/7d) with or without ischemia-reperfusion injury. Biochemical markers included creatinine and blood urea nitrogen (BUN), proinflammatory cytokines (IL-1ß, IL-6, and TNF-α), renal damage markers (cystatin C, KIM-1, and NGAL), and markers of oxidative stress such as malondialdehyde (MDA) and total antioxidant activity. RESULTS: The essential amino acid α-keto acid analog- and allopurinol-treated groups had lower levels of creatinine, BUN, renal damage markers, proinflammatory cytokines, and MDA than their corresponding ischemia-reperfusion groups. These changes were related to the essential amino acid α-keto acid analogs dosage. Total antioxidant activity was lower in essential amino acid α-keto acid analog- and allopurinol-treated groups than in the corresponding ischemia-reperfusion groups. CONCLUSIONS: This is a new report on the nephroprotective effects of essential amino acid α-keto acid analogs against ischemia-reperfusion injury. Essential amino acid α-keto acid analogs decreased the levels of biochemical markers, kidney injury markers, proinflammatory cytokines, and MDA while minimizing total antioxidant consumption.

Introducción. Los α-cetoanálogos de aminoácidos esenciales se utilizan en el tratamiento de la enfermedad renal crónica para retrasar los síntomas de la uremia. Sin embargo, se desconoce si los α-cetoanálogos de aminoácidos esenciales afectan el estrés oxidativo y la inflamación en la lesión renal aguda tal como en la producida por la isquemia-reperfusión. Objetivo. Evaluar el efecto de las α-cetoanálogos de aminoácidos esenciales sobre la lesión renal por isquemia-reperfusión en ratas Wistar. Materiales y métodos. Se emplearon 11 grupos de ratas (n=6): dos grupos recibieron solución salina fisiológica con lesión isquemia-reperfusión o sin ella (45 min/24 h), seis grupos recibieron α-cetoanálogos de aminoácidos esenciales (400, 800 o 1.200 mg/kg/24 h/7d) con lesión isquemia-reperfusión o sin ella (α-cetoanálogos de aminoácidos esenciales + isquemia-reperfusión), y dos grupos recibieron (50 mg/kg/24 h/7d) con lesión isquemia-reperfusión o sin ella. Los marcadores bioquímicos incluyeron creatinina y nitrógeno ureico en sangre (BUN), citocinas proinflamatorias (IL-1ß, IL-6 y TNF-α), marcadores de daño renal (cistatina C, KIM-1 y NGAL) y marcadores del estrés oxidativo como el malondialdehído (MDA) y la actividad antioxidante total. Resultados. Los grupos tratados con α-cetoanálogos de aminoácidos esenciales y alopurinol tuvieron niveles inferiores de creatinina, BUN, marcadores de daño renal, citocinas proinflamatorias, actividad antioxidante total y MDA que los grupos isquemia-reperfusión correspondientes. Estos cambios se asociaron con la dosis. La actividad antioxidante total fue menor en los grupos tratados con α-cetoanálogos de aminoácidos esenciales que en los grupos isquemia-reperfusión correspondientes. Conclusiones. Este es un nuevo informe de los efectos nefroprotectores de las α-cetoanálogos de aminoácidos esenciales contra la lesión isquemia-reperfusión. Los α-cetoanálogos de aminoácidos esenciales disminuyeron los niveles de los marcadores bioquímicos, de los de lesión renal, de las citocinas proinflamatorias y el MDA, a la vez que minimizaron el consumo total de antioxidantes.

Macelignan protects against renal ischemia-reperfusion injury via inhibition of inflammation and apoptosis of renal epithelial cells.

Ischemia-reperfusion injury (IRI) refers to tissue damage that occurs when blood supply returns to tissue after a period of ischemia, anoxia or hypoxia. It occurs frequently during shock, organ transplantation and heart failure. It can cause impairment or even renal failure. Macelignan is a lignin isolated from the seeds of Myristica fragrans. It has been reported to inhibit neuroinflammation and oxidative toxicity. The preventive or therapeutic effects of macelignan on renal IRI has not been reported. The present study investigated the effects of macelignan on renal IRI in rats, and the underlying mechanism(s). Healthy adult male Sprague Dawley rats (n = 50) aged 7 - 9 weeks (mean weight = 220 ± 20 g) were used in this study. The rats were randomly assigned to five groups of 10 rats each: sham   treated group, IRI group and 40 mg macelignan/kg body weight (bwt) group, 80 mg macelignan/kg bwt group, and 160 mg macelignan/kg bwt group. Ischemia-reperfusion injury was induced in the rats using standard procedure. The results showed that serum levels of creatinine, blood urea nitrogen (BUN), interleukin-6 (IL-6), tumor necrosis factor α (TNF-α) and gamma interferon (IFN-γ) were significantly higher in IRI group than in sham treated group, but were significantly and dose-dependently reduced after treatment with macelignan (p < 0.05). The activities of catalase and superoxide dismutase (SOD), and reduced glutathione (GSH) level were significantly reduced in IRI group, when compared with sham treated group, but were significantly and dose-dependently increased after treatment with macelignan (p < 0.05). However, the level of malondialdehyde (MDA) was significantly higher in IRI group than in sham treated group, but treatment with macelignan reduced it significantly and dose-dependently (p < 0.05). Macelignan also significantly and dose-dependently inhibited IRI-induced apoptosis in epithelial cells of renal tubules (p < 0.05). The results of Western blotting showed that IRI significantly upregulated the expressions of bax and caspase-3, and down-regulated the expression of bcl-2 in epithelial cells of renal tubules (p < 0.05). However, treatment with macelignan significantly and dose-dependently down-regulated the expressions of bax and caspase-3 in these cells, but significantly and dose-dependently upregulated the expression of bcl-2. These results show that macelignan confers protection on renal IRI via mechanisms involving inhibition of inflammation and apoptosis, and stimulation of natural antioxidant defense system.

Ginkgo biloba extract protects diabetic rats against cerebral ischemia­reperfusion injury by suppressing oxidative stress and upregulating the expression of glutamate transporter 1.

The current study aimed to evaluate the neuroprotective effect of Ginkgo biloba extract (GbE) on the progression of acute cerebral ischemia­reperfusion injury in diabetic rats, and to determine the molecular mechanism associated with this effect. Streptozotocin (STZ) induced diabetic rats were pretreated with GbE (50, 100 and 200 mg/kg/day; intragastric) for 3 weeks. During this period, body weight changes and fasting blood glucose levels were assessed each week. Following pretreatment, rats were subjected to suture occlusion of the middle cerebral artery for 30 min, which was followed by 24 h of reperfusion. Neurological deficits were subsequently evaluated at 2 and 24 h following reperfusion. Rats were sacrificed after 24 h reperfusion, and infarct volume and S100B content were measured to evaluate the neuroprotective effect of GbE. The results of the present study demonstrated that GbE pretreatment improved neurological scores, and reduced cerebral infarct volume and S100B content. Oxidative stress markers, including glutathione (GSH) and superoxide dismutase (SOD) were increased, and malondialdehyde (MDA) contents were reduced following GbE treatment. The levels of p­Akt, p­mTOR and glutamate transporter 1 (GLT1) were observed to be increased in GbE­pretreated rats. These results indicated that GbE pretreatment may serve a protective role against cerebral ischemia­reperfusion injury in diabetic rats by inhibiting oxidative stress reaction, upregulating the expression of Akt/mTOR and promoting GLT1 expression. In conclusion, the current study revealed the protective role and molecular mechanisms of GbE in diabetic rats with cerebral ischemia­reperfusion injury, and may provide novel insight into the future clinical treatment of this condition.

The effect of Liv-52 on liver ischemia reperfusion damage in rats.

BACKGROUND: Liver ischemia reperfusion (I/R) damage which is frequently seen in clinical hepatobiliary surgeries has no effective treatment for it. Liv-52, known to have hepatoprotective effects, is a natural antioxidant drug licensed by the Ministry of Health of India. The aim of our study is to investigate the effect of Liv-52 on liver damage induced by I/R in rats. METHODS: Albino Wistar male rats were divided into three groups; liver I/R (IR), 20 mg/kg Liv-52 + liver ischemia reperfusion (LIR) and sham operation applied to control group (HG). Liv-52 was administered to the LIR group (n = 6) 1 h prior to I/R application and distilled water was given orally to IR (n = 6) and HG (n = 6) groups as a solvent. Ischemia was determined as 1 h, and reperfusion was identified as 6 h in animals. RESULTS: Increased levels of alanine aminotransferase, aspartate aminotransferase and lactate dehydrogenase, malondialdehyde, myeloperoxidase, and decreased levels of superoxide dismutase, and glutathione related enzymes caused by I/R application have been converged to healthy group level with Liv-52 treatment and the damage in liver tissue has been improved histopathologically. CONCLUSIONS: Liv-52 may be beneficial for preventing liver I/R damage in pre-surgery application.

Sitagliptin protects male albino rats with testicular ischaemia/reperfusion damage: Modulation of VCAM-1 and VEGF-A.

Twisting of the spermatic cord is considered a popular problem in the urological field, which may lead to testicular necrosis and male infertility. Sitagliptin, a glucose-lowering agent, proved to have a vindicatory function in myocardial and renal ischaemia/reperfusion (I/R), but its role in testicular I/R has not yet been studied. The current work investigates its capability to recover the testicular I/R injury with shedding more light on the mechanism of its action. Four groups were used: sham, sham pretreated with sitagliptin, I/R and sitagliptin/I/R-pretreated groups. The outcomes proved that I/R significantly decreased the serum testosterone, with a major increase in oxidative, inflammatory and nitrosative stress, along with a reduction in testicular vascular endothelial growth factor-A level with marked germinal cell apoptosis. However, pretreatment with sitagliptin significantly reversed the profound testicular I/R damaging effects, on the basis of its antioxidant, anti-inflammatory and anti-apoptotic activities with the ability of recuperation of the testicular vascularity.

Exploring the effects of Gastrodia elata Blume on the treatment of cerebral ischemia-reperfusion injury using UPLC-Q/TOF-MS-based plasma metabolomics.

Gastrodia elata Blume (Orchidaceae, GEB) is a medicinal plant that has been widely used in the treatment of cerebrovascular disease. This study explored the protective effects of GEB against cerebral ischemia-reperfusion using Information-Dependent Acquisition (IDA)-mediated UPLC-Q/TOF-MS-based plasma metabolomics. Cerebral ischemia-reperfusion (IR) injury was induced in male Wistar rats using the Zea Longa method. Biochemical and histological assays were performed to evaluate the therapeutic effects of GEB on IR rats. We found that the neurobehavioral scores and infarction areas of GEB and nimodipine treated groups were dramatically lower than those of the IR groups. Hematoxylin and Eosin (HE) staining and TdT-mediated dUTP Nick-End Labeling (TUNEL) showed that GEB significantly improved neuronal injury and prevented neuronal apoptosis. Biochemical analysis revealed that GEB prevented cerebral ischemia-reperfusion injury by regulating inflammation and oxidative injury. Through ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry-metabolomics-based approaches, 43 plasma metabolites related to GEB treatment were detected, 6 of which significantly differed (p < 0.05) between the model and GEB groups. The levels of l-histidine, sphinganine, thymine, spermidine and deoxycytidine in the IR group were significantly higher than those in the sham group, but decreased following GEB treatment. Arachidonic acid levels were lower in the IR group, but dramatically increased in response to GEB. Pharmacodynamics and metabolomics confirmed that the mechanism of GEB in the treatment of cerebral ischemia was not only related to the reduction of inflammation, oxidation, neurotoxicity, and apoptosis, but also mediated through arachidonic acid metabolism, histidine metabolism, pyrimidine metabolism, arginine and proline metabolism, sphingolipid metabolism, and glycerophospholipid metabolism in vivo.

Montmorency cherry supplementation attenuates vascular dysfunction induced by prolonged forearm occlusion in overweight, middle-aged men.

Flavonoid supplementation improves brachial artery flow-mediated dilation (FMD), but it is not known whether flavonoids protect against vascular dysfunction induced by ischemia-reperfusion (IR) injury and associated respiratory burst. In a randomized, double-blind, placebo-controlled, crossover study, we investigated whether 4 wk supplementation with freeze-dried Montmorency cherry (MC) attenuated suppression of FMD after IR induced by prolonged forearm occlusion. Twelve physically inactive overweight, middle-aged men (52.8 ± 5.8 yr, BMI: 28.1 ± 5.3 kg/m2) consumed MC (235 mg/day anthocyanins) or placebo capsules for 4 wk, with supplementation blocks separated by 4 wk washout. Before and after each supplementation block, FMD responses and plasma nitrate and nitrite ([ NO2- ]) concentrations were measured at baseline and 15, 30, and 45 min after prolonged (20 min) forearm occlusion. FMD response was significantly depressed by the prolonged occlusion ( P < 0.001). After a 45-min reperfusion, FMD was restored to baseline levels after MC (ΔFMD presupplementation: -30.5 ± 8.4%, postsupplementation: -0.6 ± 9.5%) but not placebo supplementation (ΔFMD presupplementation: -11.6 ± 10.6, postsupplementation: -25.4 ± 4.0%; condition × supplement interaction: P = 0.038). Plasma [ NO2- ] decreased after prolonged occlusion but recovered faster after MC compared with placebo (Δ45 min to baseline; MC: presupplementation: -15.3 ± 9.6, postsupplementation: -6.2 ± 8.1; Placebo: presupplementation: -16.3 ± 5.9, postsupplementation: -27.7 ± 11.1 nmol/l; condition × supplement × time interaction: P = 0.033). Plasma peroxiredoxin concentration ([Prx2]) was significantly higher after MC (presupplementation: 22.8 ± 1.4, postsupplementation: 28.0 ± 2.4 ng/ml, P = 0.029) but not after placebo supplementation (presupplementation: 22.1 ± 2.2, postsupplementation: 23.7 ± 1.5 ng/ml). In conclusion, 4 wk MC supplementation enhanced recovery of endothelium-dependent vasodilatation after IR, in parallel with faster recovery of plasma [ NO2- ], suggesting NO dependency. These protective effects seem to be related to increased plasma [Prx2], presumably conferring protection against the respiratory burst during reperfusion. NEW & NOTEWORTHY This is the first study to demonstrate that 4 wk of Montmorency cherry powder supplementation exerted protective effects on endothelium-dependent vasodilation after transient ischemia-reperfusion injury in overweight, physically inactive, nonmedicated, hypertensive middle-aged men. These effects seem to be due to increased nitric oxide availability, as evidenced by higher plasma nitrite concentration and peak arterial diameter during the flow-mediated dilation measurement. This may be a consequence of increased concentration of peroxiredoxin and other antioxidant systems and, hence, reduced reactive oxygen species exposure.

Cold-inducible RNA-binding protein-derived peptide C23 attenuates inflammation and tissue injury in a murine model of intestinal ischemia-reperfusion.

BACKGROUND: Cold-inducible RNA-binding protein is a novel damage-associated molecular pattern that causes inflammation. C23, a short peptide derived from cold-inducible RNA-binding protein, has been found to have efficacy in blocking cold-inducible RNA-binding protein's activity. We hypothesized that C23 reduces inflammation and tissue injury induced by intestinal ischemia-reperfusion. METHODS: Male C57BL/6 mice were subjected to 60 minutes of intestinal ischemia by clamping the superior mesenteric artery. Immediately after reperfusion, either normal saline (vehicle) or C23 peptide (8 mg/kg body weight) was injected intraperitoneally. Four hours after reperfusion, blood, intestinal, and lung tissues were collected for analysis of inflammatory and tissue injury parameters. RESULTS: Cold-inducible RNA-binding protein levels in the intestinal tissues were significantly increased following intestinal ischemia-reperfusion. Histologic examination of the intestine revealed a significant reduction in injury score in the C23 group by 48% as compared with the vehicles after intestinal ischemia-reperfusion. The serum levels of lactate dehydrogenase and aspartate aminotransferase were increased in animals that underwent vehicle-treated intestinal ischemia-reperfusion, whereas C23-treated animals exhibited significant reductions by 48% and 53%, respectively. The serum and intestinal tissue levels of tumor necrosis factor α were elevated in vehicle-treated intestinal ischemia-reperfusion mice but decreased by 72% and 69%, respectively, in C23-treated mice. Interleukin-6 mRNA levels in the lungs were reduced by 86% in the C23-treated group in comparison to the vehicle-treated group after intestinal ischemia-reperfusion. Expression of macrophage inflammatory protein 2 and level of myeloperoxidase activity in the lungs were dramatically increased after intestinal ischemia-reperfusion and significantly reduced by 91% and 25%, respectively, in the C23-treated group. CONCLUSION: C23 has potential to be developed into a possible therapy for reperfusion injury after mesenteric ischemia and reperfusion.

UPLC-HRMS-Based Plasma Metabolomic Profiling of Novel Biomarkers by Treatment with KDZI in Cerebral Ischemia Reperfusion Rats.

Kudiezi injection (KDZI), also known as Diemailing injection, is a traditional Chinese medicine injection of the composite plant Ixeris sonchifolia Hance (also known as Kudiezi), and has been widely used to treat coronary heart disease, angina pectoris, and cerebral infarction, but its pharmacological mechanisms remain unclear. This study is designed to explore the effects of KDZI on middle cerebral artery occlusion and reperfusion (MCAO/R) rats, and to identify metabolic features of cerebral ischemia reperfusion by using a nontargeted metabolic profiling method based on ultra-performance liquid chromatography-high resolution mass spectrometry (UPLC-HRMS). In this process, 32 potential biomarkers were found in plasma. KDZI significantly upregulated the levels of taurochenodesoxycholic acid, leucine, l-phenylalanine, l-tryptophan, arachidonic acid (ARA), and phosphatidyl ethanolamines (PE), phosphatidyl cholines (PC) and downregulated the levels of l-valine and 5-hydroxyindole-3-acetic acid (5-HIAA) in plasma. The results indicated that the mechanisms of KDZI on MCAO/R were related to the mechanisms of amino acid and lipid metabolism.

The effects of zinc and melatonin on muscle ischaemi-reperfusion injury in rat.

Ischemia-reperfusion leads to damage in cell or tissue due to insufficient blood flow. The aim of present study was to determine the effect of zinc, melatonin and zinc + melatonin supplementations during 3 weeks on muscle tissue and plasma MDA and GSH levels. This study was performed on 38 male Wistar-Albino rats. Experiments groups were designed as sham-control, ischemia-reperfusion (I/R), zinc + I/R, melatonin + I/R and zinc + melatonin + I/R Ischemia-reperfusion was induced by left femoral artery occlusion (1 hour) and reopening (1 hour).  At the end of experiments tissue and blood samples were analysed for MDA and GSH. MDA levels were increased, GSH levels decreased in I/R groups. However, zinc and melatonin supplementation inhibited  MDA and increased GSH levels in I/R groups. The results of present study show that increased lipid peroxidation in muscle tissue by ischemia-reperfusion may be prevented by zinc and melatonin or zinc plus melatonin supplementation.

Hypericum Humifusum Leaves Attenuates Hepatic Ischemia-Reperfusion Injury in a Rat Model.

INTRODUCTION: Effective prevention strategies require specific actions during the different phases of ischemia-reperfusion (I-R) injury. The objective of our study is to evaluate the effect of aqueous extract of Hypericum humifusum leaves (HHL) on liver I-R model in Rat. MATERIAL AND METHODS: Animals were subjected to 90 min of hepatic ischemia followed by reperfusion (120 min). HHL extract (25 mg/mL/kg) was injected 15 min before reperfusion. To evaluate the effect of HHL extract on I-R, we have monitored transaminases levels, Malondialdehyde (MDA) concentration, histological lesions (apoptosis and necrosis) and compared the results to a reference oxidant vitamin E. RESULTS: The determination of total phenol extracts of HHL was 59.91 ± 0.35 mg of Gallic Acid/g dry plant material with higher antioxidant activity (91.73% ± 1.67) compared to vitamin E (87.42%). Using aqueous extract of HHL, we noted a significant decrease of AST and ALT [1129 UI (585/1995) and 768 UI (335/1375)] compared to no-treated group [5,585.5 UI (5,035/12,070) and 8,099.5 UI (5,040/12,326)] as a decrease in MDA content [85.7% protection (50.9/91.5)]. HHL extract reduce the damage induced by I-R of 48.7% (27/48.7) and 96.1% (95.7/96.5) for necrosis and apoptosis lesions respectively. CONCLUSION: HHL aqueous extract have potential to protect liver from the damage effect induced by I-R better than vitamin E solution.

Pretreatment with intravenous fish oil reduces hepatic ischemia reperfusion injury in a murine model.

BACKGROUND: Ischemia reperfusion injury is a barrier to liver surgery and transplantation, particularly for steatotic livers. The purpose of this study was to determine if pretreatment with a single dose of intravenous fish oil decreases hepatic ischemia reperfusion injury and improves recovery of injured livers. METHODS: Sixty adult male C57BL/6 mice received 1 g/kg intravenous fish oil (Omegaven, Fresenius Kabi) or isovolumetric 0.9% NaCl (saline) via tail vein 1 hour before 30 minutes of 70% hepatic ischemia. Animals were killed 4, 8, or 24 hours postreperfusion, and livers were harvested for histologic analysis. RESULTS: Four hours postreperfusion, saline-treated livers demonstrated marked ischemia diffusely around the central veins, while intravenous fish oil-treated livers demonstrated only patchy necrosis with intervening normal parenchyma. Eight hours postreperfusion, all livers demonstrated pale areas of cell loss with surrounding regenerating hepatocytes. Ki67 staining confirmed 14.4/10 high-powered field (95% confidence interval, 3.2-25.6) more regenerating hepatocytes around areas of necrosis in intravenous fish oil-treated livers. Twenty-four hours postreperfusion, all livers demonstrated patchy areas of necrosis, with an 89% (95% confidence interval, 85-92) decrease in the area of necrosis in intravenous fish oil-treated livers. CONCLUSION: Intravenous fish oil treatment prior to hepatic ischemia reperfusion injury decreased the area of hepatic necrosis and increased hepatocyte regeneration compared to saline treatment in a mouse model.

In Vivo Therapeutic Effect of Vaccinium Meridionale Swartz in Ischemia-Reperfusion Induced Male Albino Rats.

This study was aimed to investigate the cardioprotective and antioxidant effect of Vaccinium meridionale Swartz in ischemia-induced male albino Wistar strain rats. Rats were grouped into 5 of 6 numbers each. Group I served as a sham, group II served as control and group III, IV, and V served for 1, 10, and 25 mg/kg/d of an extract of Vaccinium meridionale Swartz for 15 consecutive days of treatment. Serum marker enzymes, lipid peroxidation, and myeloperoxidase were increased, whereas antioxidant enzymes were reduced in control due to injury. Increased phenol and anthocyanin contents and increased free radical scavenging activity was noted following treatment. Serum marker enzymes, necrosis, and lipid peroxidation, were reduced, whereas antioxidant enzymes and reduced glutathione were increased. Nitric oxide synthase and Akt expression were also increased following treatment. Taking all these data together, it is suggested that Vaccinium meridionale Swartz may be a potential therapeutic agent for the treatment of ischemic injury.

Magnolol Reduces Renal Ischemia and Reperfusion Injury via Inhibition of Apoptosis.

Magnolol, a constituent of the bark of Magnolia officinalis, has been reported to decrease myocardial stunning and infarct size. In this study, we investigated whether magnolol can reduce renal ischemia and reperfusion (I/R) injury. Renal I/R, induced by a 60-min occlusion of bilateral renal arteries and a 24-h reperfusion, significantly increased blood urea nitrogen (BUN) and creatinine levels, and caused histological damage to the kidneys of rats. Apoptosis, as evaluated by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining and caspase-3 activation, was significantly increased in the kidneys. Furthermore, serum levels of tumor necrosis factor-[Formula: see text] (TNF-[Formula: see text]), interleukin-1ß (IL-1ß), and interleukin-6 (IL-6) were significantly elevated, while the interleukin-10 (IL-10) level was suppressed. However, intravenous pretreatment with magnolol at doses of 0.003[Formula: see text]mg/kg and 0.006[Formula: see text]mg/kg 10[Formula: see text]min before renal I/R significantly limited the increases of BUN, creatinine, the histological damage, and apoptosis in the kidneys. The increases in TNF-[Formula: see text], IL-1ß, and IL-6, and the decrease in IL-10 were also significantly inhibited. Additionally, magnolol increased Bcl-2 and decreased Bax in the kidneys. Phosphorylation of the prosurvival kinases, including Akt and extracellular signal-regulated kinases 1 and 2 (ERK1/2), was elevated, while phosphorylation of the pro-apoptotic mitogen-activated protein kinases, including p38 and c-Jun N-terminal kinase (JNK), was suppressed. In conclusion, magnolol reduces renal I/R injury. The underlying mechanisms for this effect might be related to the prevention of apoptosis, possibly via the inhibition of both extrinsic and intrinsic apoptotic pathways, including the reduction of TNF-[Formula: see text] production and the modulation of pro- and anti-apoptotic signaling elements.

The macrophage stimulating anti-cancer agent, RRx-001, protects against ischemia-reperfusion injury.

BACKGROUND: RRx-001, a clinical macrophage-stimulating anti-cancer agent that also produces nitric oxide (NO) was studied in a model of ischemia-reperfusion injury. METHODS: The production of NO is dependent on the oxygen tension because nitric oxide synthases convert l-arginine to NO and l-citrulline in the presence of O2. Since the P450 enzymes, which metabolize nitrate esters such as nitroglycerin are dependent on oxygen, the generation of 'exogenous' NO is also sensitive to alterations in tissue PO2. I/R injury was studied in a hamster chamber window, with compression of the periphery of the window for 1 h to induce ischemia. Animals received RRx-001 (5 mg/kg) 24 h before ischemia and sodium nitrite (10 nmols/kg) was supplemented 10 min after the start of reperfusion. Vessel diameter, blood flow, adherent leukocytes, and functional capillary density were assessed by intravital microscopy at 0.5, 2, and 24 h following the release of the ischemia. RESULTS: The results demonstrated that, compared to control, RRx-001 preconditioning increased blood flow and functional capillary density, and preserved tissue viability in the absence of side effects over a sustained time period. CONCLUSION: Thus, RRx-001 may serve as a long-lived protective agent during postsurgical restoration of flow and other ischemia-reperfusion associated conditions, increasing blood flow and functional capillary density as well as preserving tissue viability in the absence of side effects.

Protective effect of glutamine on the main and adjacent organs damaged by ischemia-reperfusion in rats.

Intestinal ischemia and reperfusion (I/R) causes cellular and tissue damage to the intestine and remote organs such as the liver. Increased production of ROS and nitric oxide and dysregulation of cytoprotective enzymes may be involved in intestinal I/R. The aim was to evaluate the protective effects of glutamine on the intestine and liver of rats with intestinal I/R injury. Twenty male Wistar rats (300 g) were divided into four groups: sham-operated (SO), glutamine + SO (G + SO), I/R, and glutamine + I/R (G + I/R). Occlusion of the SMA for 30 min was followed by 15-min reperfusion. Glutamine (25 mg/kg/day) was administered once daily 24 and 48 h before I/R induction. Blood and tissue of were collected for aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels, histopathological analysis, immunohistochemistry of IL-1ß and TNF-α, thiobarbituric acid reactive substance (TBARS) and nitric oxide, Nrf2/keap1, superoxide dismutase (SOD), NADPH quinone oxidoreductase1 (NQO1), inducible nitric oxide synthase (iNOS), heat shock protein (HSP70), glucose-regulated protein 78 (GRP78), and activating transcription factor 6 (ATF-6) by western blot. Statistic analysis by ANOVA-Student-Newman-Keuls test (mean ± SE) significantly was p < 0.05. Tissue damage, AST, ALT, IL-1ß, TNF-α, TBARS, NO, Keap1, iNOS, GRP78, and ATF-6 expression were significantly lower in the G + I/R group as compared to the I/R group. Expression of Nrf2, SOD, NQO1, and HSP70, was significantly higher in the G + I/R group as compared to I/R group. Pre-treatment with glutamine provided protection against oxidative damage in the intestine and liver in an experimental model of intestinal I/R.

Hyperbaric Oxygenation Protects Against Ischemia-Reperfusion Injury in Transplanted Rat Kidneys by Triggering Autophagy and Inhibiting Inflammatory Response.

BACKGROUND Ischemia-reperfusion injury (IRI) is a clinically common pathologic process defined as the inability to improve neuronal function. This study aimed to investigate the pathological mechanism of IRI and to explore effects of hyperbaric oxygenation (HBO) on autophagy and inflammatory response in IRI. MATERIAL AND METHODS Ninety Sprague-Dawley (SD) rats were randomly divided into a Sham group, a kidney transplant group (Trans), and a kidney transplant plus HBO treatment group (Trans+HBO). The kidney was harvested from the donor and transplanted to recipient rats according to a previously reported study. Rats were anesthetized using pentobarbital-natrium, and the kidney was resected and fixed in 4% paraformaldehyde. Serum creatinine (Scr) was detected using an automatic biochemical analyzer. The interleukin-6 (IL-6) level was assessed using enzyme-linked immunosorbent assay (ELISA). LC-3 was examined using indirect immunofluorescence assay and immunochemistry assay. LC-3 mRNA levels were analyzed using real-time PCR (RT-PCR). RESULTS The kidney transplant IRI model was successfully established. Scr and IL-6 levels were significantly increased in the Trans group (P<0.05). HBO significantly enhanced Scr and IL-6 levels. Scr was positively correlated with IL-6 levels (r-0.607, P<0.05). HBO increased LC-3 protein and mRNA expression in kidney-transplanted rats compared to the Sham and Trans group (P<0.05). Moreover, immunofluorescence assay also showed that LC-3 protein mainly distributes along renal tubular epithelial cells in a linear manner. CONCLUSIONS Autophagy dysfunction and inflammatory response after renal transplantation play important roles in processes of IRI. HBO treatment protects against the renal injury of IRI in renal tissues at the early stage, which may be triggered by the IL-6 pathway.

The protection effects of (1E,6E)-1,7-diphenylhepta-1,6-diene-3,5-dione, a curcumin analogue, against operative liver injury in rats.

The relationship between the chemistry characteristic and the hepatoprotective effects of (1E,6E)-1,7-diphenylhepta-1,6-diene-3,5-dione (DDD), a curcumin analogue, in operative liver injury rats was investigated to reveal the mechanism of hepatic protection effects of DDD. DDD (1.2-4.8mmol/kg) was administrated 10min before reperfusion phase in hepatic ischemia-reperfusion injury (IRI) rats. DDD (4.8mmol/kg) administrated 10min before ischemia and N-acetylcysteine (NAC) (4.8mmol/kg) administrated 10min before reperfusion were included for comparative studies. The plasma liver enzyme activities, histopathological indices and markers of lipid peroxide were determined to evaluate the hepatic protection effects. Effects of DDD on succinate dehydrogenase (SDH) activity were also investigated. DDD showed dose-dependent hepatocyte protections when administrated 10min before reperfusion stages in hepatic IRI rats. DDD showed almost equivalent hepatoprotective effects when administrated 10min before ischemia phase demonstrating that DDD acted on the reperfusion stages selectively against the hepatic IRI, instead of ischemia phase. NAC was not effective against hepatic IRI when treated 10min before reperfusion because of the higher pKa of NAC. In additional, DDD had no effect on the SDH both in hepatic IRI rats and in mitochondria. In conclusion, DDD had dose-dependent hepatocyte protections in the reperfusion stages in hepatic IRI rats, while the observed hepatocyte protections of DDD did not involve SDH activities. ß-Diketone structures of DDD were crucial for the hepatocyte protections. The abilities of DDD to clear up the unsaturated aldehydes related with the enolate nucleophilicity and the pKa. DDD might be a promising candidate to treat hepatic IRI.