Rutin in rat liver ischemia/reperfusion injury: effect on DDAH/NOS pathway

Effects of iNOS in Hepatic Warm Ischaemia and Reperfusion Models in Mice and Rats: A Systematic Review and Meta-Analysis

Warm ischaemia is usually induced by the Pringle manoeuver (PM) during hepatectomy. Currently, there is no widely accepted standard protocol to minimise ischaemia-related injury, so reducing ischaemia-reperfusion damage is an active area of research. This systematic review and meta-analysis focused on inducible nitric oxide synthase (iNOS) as an early inflammatory response to hepatic ischaemia reperfusion injury (HIRI) in mouse- and rat-liver models. A systematic search of studies was performed within three databases. Studies meeting the inclusion criteria were subjected to qualitative and quantitative synthesis of results. We performed a meta-analysis of studies grouped by different HIRI models and ischaemia times. Additionally, we investigated a possible correlation of endothelial nitric oxide synthase (eNOS) and nitric oxide (NO) regulation with iNOS expression. Of 124 included studies, 49 were eligible for the meta-analysis, revealing that iNOS was upregulated in almost all HIRIs. We were able to show an increase of iNOS regardless of ischemia or reperfusion time. Additionally, we found no direct associations of eNOS or NO with iNOS. A sex gap of primarily male experimental animals used was observed, leading to a higher risk of outcomes not being translatable to humans of all sexes.

Effects of GIT-27NO, a NO-donating compound, on hepatic ischemia/reperfusion injury

Hepatic ischemia/reperfusion injury (IRI) is a clinical condition that may lead to cellular injury and organ dysfunction that can be observed in different conditions, such as trauma, shock, liver resection, and transplantation. Moderate levels of nitric oxide (NO) produced by the endothelial isoform of the NO synthase protect against liver IRI. GIT-27NO is a NO-derivative of the toll-like receptor 4 antagonist VGX-1027 that has been shown to possess both antineoplastic and immunomodulatory properties in vitro and in vivo. In this study, we have investigated the effects of this compound in vitro, in a model of oxidative stress induced in HepG2 cells by hydrogen peroxide (H₂O₂), and in vivo, in a rat model of IRI of the liver. GIT-27NO significantly counteracted the toxic effects induced by the H₂O₂ on the HepG2 cells and in vivo, GIT-27NO reduced the transaminase levels and the histological liver injury by reducing necrotic areas with preservation of viable tissue. These effects were almost similar to that of the positive control drug dimethyl fumarate. These data suggest that the beneficial effect of GIT-27NO in the hepatic IRI can be secondary to anti-oxidative effects and hepatocyte necrosis reduction probably mediated by NO release.

Piper sarmentosum Promotes Endothelial Nitric Oxide Production by Reducing Asymmetric Dimethylarginine in Tumor Necrosis Factor-α-Induced Human Umbilical Vein Endothelial Cells

Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of endothelial nitric oxide synthase (eNOS). ADMA is degraded by dimethylarginine dimethylaminohydrolase (DDAH). Elevated levels of ADMA lead to reduction in nitric oxide (NO) production, which is linked to endothelial dysfunction and atherosclerosis. Piper sarmentosum is an herb that has shown stimulation on endothelial NO production by increasing both expression and activity of eNOS. Thus, this study determined whether the positive effect of P. sarmentosum on NO production is related to its modulation on the DDAH-ADMA pathway in cultured human umbilical vein endothelial cells (HUVEC) exposed to tumor necrosis factor-α (TNF-α). HUVEC were divided into four groups: control, treatment with 250 µg/ml of aqueous extract of P. sarmentosum leaves (AEPS), treatment with 30 ng/ml of TNF-α, and concomitant treatment with AEPS and TNF-α for 24 h. After treatments, HUVEC were collected to measure DDAH1 messenger RNA (mRNA) expression using quantitative real-time polymerase chain reaction. DDAH1 protein level was measured using enzyme-linked immunosorbent assay (ELISA), and DDAH enzyme activity was measured using colorimetric assay. ADMA concentration was measured using ELISA, and NO level was measured using Griess assay. Compared to control, TNF-α-treated HUVEC showed reduction in DDAH1 mRNA expression (P < 0.05), DDAH1 protein level (P < 0.01), and DDAH activity (P < 0.05). Treatment with AEPS successfully increased DDAH1 mRNA expression (P < 0.05), DDAH1 protein level (P < 0.01), and DDAH activity (P < 0.05) in TNF-α-treated HUVEC. Treatment with TNF-α caused an increase in ADMA level (P < 0.01) and a decrease in endothelial NO production (P < 0.001). Whereas treatment with AEPS was able to reduce ADMA level (P < 0.01) and restore NO (P < 0.001) in TNF-α-treated HUVEC. The results suggested that AEPS promotes endothelial NO production by stimulating DDAH activity and thus reducing ADMA level in TNF-α-treated HUVEC.

Heme Oxygenase-1 Inhibition Sensitizes Human Prostate Cancer Cells towards Glucose Deprivation and Metformin-Mediated Cell Death

High levels of heme oxygenase (HO)-1 have been frequently reported in different human cancers, playing a major role in drug resistance and regulation of cancer cell redox homeostasis. Metformin (MET), a drug widely used for type 2 diabetes, has recently gained interest for treating several cancers. Recent studies indicated that the anti-proliferative effects of metformin in cancer cells are highly dependent on glucose concentration. The present work was directed to determine whether use of a specific inhibitor of HO-1 activity, alone or in combination with metformin, affected metastatic prostate cancer cell viability under different concentrations of glucose. MTT assay and the xCELLigence system were used to evaluate cell viability and cell proliferation in DU145 human prostate cancer cells. Cell apoptosis and reactive oxygen species were analyzed by flow cytometry. The activity of HO-1 was inhibited using a selective imidazole-based inhibitor; genes associated with antioxidant systems and cell death were evaluated by qRT-PCR. Our study demonstrates that metformin suppressed prostate cancer growth in vitro and increased oxidative stress. Disrupting the antioxidant HO-1 activity, especially under low glucose concentration, could be an attractive approach to potentiate metformin antineoplastic effects and could provide a biochemical basis for developing HO-1-targeting drugs against solid tumors.

Protective Effects of Caffeic Acid Phenethyl Ester (CAPE) and Novel Cape Analogue as Inducers of Heme Oxygenase-1 in Streptozotocin-Induced Type 1 Diabetic Rats

Type 1 diabetes mellitus (T1D) is a chronic autoimmune disease resulting in the destruction of insulin producing β-cells of the pancreas, with consequent insulin deficiency and excessive glucose production. Hyperglycemia results in increased levels of reactive oxygen species (ROS) and nitrogen species (RNS) with consequent oxidative/nitrosative stress and tissue damage. Oxidative damage of the pancreatic tissue may contribute to endothelial dysfunction associated with diabetes. The aim of the present study was to investigate if the potentially protective effects of phenethyl ester of caffeic acid (CAPE), a natural phenolic compound occurring in a variety of plants and derived from honeybee hive propolis, and of a novel CAPE analogue, as heme oxygenase-1 (HO-1) inducers, could reduce pancreatic oxidative damage induced by excessive amount of glucose, affecting the nitric oxide synthase/dimethylarginine dimethylaminohydrolase (NOS/DDAH) pathway in streptozotocin-induced type 1 diabetic rats. Our data demonstrated that inducible nitric oxide synthase/gamma-Glutamyl-cysteine ligase (iNOS/GGCL) and DDAH dysregulation may play a key role in high glucose mediated oxidative stress, whereas HO-1 inducers such as CAPE or its more potent derivatives may be useful in diabetes and other stress-induced pathological conditions.

Rutin attenuates cerebral ischemia-reperfusion injury in ovariectomized rats via estrogen-receptor-mediated BDNF-TrkB and NGF-TrkA signaling

Rutin, a flavonoid glycoside, has been reported to exert neuroprotective effects. Loss of endogenous estrogen and dysregulation of the estrogen receptor (ER) signaling pathway are associated with the increased risk of stroke in women after menopause. This study was performed to investigate whether rutin could protect against cerebral ischemia by modulating the ER pathway. Ovariectomized (OVX) rats were given intraperitoneal injections of vehicle (dimethyl sulfoxide), rutin (100 mg/kg body mass) or 17β-estradiol (100 μg/kg body mass) for 5 consecutive days. Then, the rats were subjected to middle cerebral artery occlusion (MCAO) for 1 h followed by a 24 h reperfusion to establish the cerebral ischemia-reperfusion (I/R) injury. We found that rutin improved the sensorimotor performance and recognition memory of rats subjected to I/R, decreased the infarct size, and attenuated neuron loss. Rutin treatment also increased the levels of ERα, ERβ, brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), tropomyosin receptor kinase A (TrkA), TrkB, and phospho-cAMP-responsive element binding protein (p-CREB) in rat hippocampus and cerebral cortex. The protective effects of rutin were comparable to that of 17β-estradiol, and were partially blocked by ICI182780, an ER antagonist. The above results suggest that rutin preconditioning ameliorates cerebral I/R injury in OVX rats through ER-mediated BDNF-TrkB and NGF-TrkA signaling.

Intraperitoneal administration of apigenin in liver ischemia/reperfusion injury protective effects

BACKGROUND/AIMS

Hepatic injury caused by ischemia/reperfusion (I/R) is a clinical problem associated with major liver surgery. Among other flavonoids, apigenin has shown a promising effect on I/R cases. In this study, we have investigated the effects of apigenin after liver I/R injury in rats.

MATERIALS AND METHODS

Forty eight rats were randomized into the following eight groups: (1) Control-sham group: rats subjected to the surgical procedure, except for liver I/R; (2) DMSO group: rats subjected to surgery, except for liver I/R given the apigenin solvent dimethyl-sulfoxide intraperitoneally; (3) C60 group; (4) C120 group; (5) C240 group: rats underwent liver ischemia for 45 min followed by reperfusion for 60 min, 120 min, and 240 min; (6) AP60 group; (7) AP120 group; (8) AP240 group: rats underwent liver ischemia for 45 min, and then given apigenin (5 mg) intraperitoneally followed by reperfusion for 60 min, 120 min, and 240 min. Reverse transcription polymerase chain reaction was performed on liver tissues to measure BCL-2/BAX expression, enzyme-linked immunosorbent assay to measure M30/M65 and ICAM-1. Immunohistochemistry was used to identify M30 biomarker in liver tissues.

STATISTICAL ANALYSIS

Quantitative variables were tested by Kolmogorov-Smirnov test, repeated measures analysis of variance/Friedman test. Gene levels were assessed by Student's t-test/Mann-Whitney U-test.

RESULTS

BCL-2 levels were significantly higher in I/R apigenin groups than in I/R control groups. BAX levels were lower in the AP240 group than in C240 group. Prolongation of reperfusion resulted in increased activation of M30. ICAM-1 levels were lower in the AP240 group than in C240 group.

CONCLUSIONS

Apigenin seems to inhibit the process of apoptosis and ameliorate the hepatic I/R injury.

Shinzami Korean purple-fleshed sweet potato extract prevents ischaemia-reperfusion-induced liver damage in rats

BACKGROUND

This study was designed to investigate the hepatoprotective effect of an extract from Shinzami, a variety of purple sweet potato, in rats injured by hepatic ischaemia-reperfusion (I/R).

RESULTS

Pretreatment with Shinzami extract decreased the aspirate aminotransferase and alanine aminotransferase serum levels in our hepatic I/R rat model. The glutathione level and superoxide dismutase activity level were significantly higher in the rats pretreated with the Shinzami extract compared with the hepatic I/R rats, and the glutathione peroxidase activity level was higher in pretreated rats. The total anthocyanins extracted from Shinzami, however, only increased the superoxide dismutase activity level in the hepatic I/R rats. Rats pretreated with the Shinzami extract or anthocyanins demonstrated attenuated hepatic pathological changes, such as hepatic distortion, haemorrhage, necrosis and inflammatory cell infiltration compared with the hepatic I/R control rats.

CONCLUSION

Shinzami extract and anthocyanins have a hepatoprotective effect on the liver damage induced by hepatic I/R by improving antioxidant status. Furthermore, the Shinzami extract may have a more potent effect on the antioxidant status compared with the Shinzami anthocyanins alone.

Liver plays a central role in asymmetric dimethylarginine-mediated organ injury

Asymmetric-dimethylarginine (ADMA) competes with L-arginine for each of the three isoforms of nitric oxide synthase: endothelial; neuronal; inducible. ADMA is synthesized by protein methyltransferases followed by proteolytic degradation. ADMA is metabolized to citrulline and dimethylamine, by dimethylarginine dimethylaminohydrolase (DDAH) and enters cells through cationic amino-acid transporters extensively expressed in the liver. The liver plays a crucial role in ADMA metabolism by DDAH-1 and, as has been recently demonstrated, it is also responsible for ADMA biliary excretion. A correlation has been demonstrated between plasma ADMA levels and the degree of hepatic dysfunction in patients suffering from liver diseases with varying aetiologies: plasma ADMA levels are increased in patients with liver cirrhosis, alcoholic hepatitis and acute liver failure. The mechanism by which liver dysfunction results in raised ADMA concentrations is probably due to impaired activity of DDAH due to severe inflammation, oxidative stress, and direct damage to DDAH. High plasma ADMA levels are also relevant as they are associated with the onset of multi-organ failure (MOF). Increased plasma concentration of ADMA was identified as an independent risk factor for MOF in critically-ill patients causing enhanced Intensive Care Unit mortality: a significant reduction in nitric oxide synthesis, leading to malperfusion in various organs, eventually culminating in multi organs dysfunction.

Changes in ADMA/DDAH pathway after hepatic ischemia/reperfusion injury in rats: the role of bile

We investigated the effects of hepatic ischemia/reperfusion (I/R) injury on asymmetric dimethylarginine (ADMA, a nitric oxide synthase inhibitor), protein methyltransferase (PRMT) and dimethylarginine dimethylaminohydrolase (DDAH) (involved, resp., in ADMA synthesis and degradation), and the cationic transporter (CAT). Male Wistar rats were subjected to 30 or 60 min hepatic ischemia followed by 60 min reperfusion. ADMA levels in serum and bile were determined. Tissue ADMA, DDAH activity, DDAH-1 and CAT-2 protein, DDAH-1 and PRMT-1 mRNA expression, GSH/GSSG, ROS production, and lipid peroxidation were detected. ADMA was found in bile. I/R increased serum and bile ADMA levels while an intracellular decrease was detected after 60 min ischemia. Decreased DDAH activity, mRNA, and protein expression were observed at the end of reperfusion. No significant difference was observed in GSH/GSSG, ROS, lipid peroxidation, and CAT-2; a decrease in PRMT-1 mRNA expression was found after I/R. Liver is responsible for the biliary excretion of ADMA, as documented here for the first time, and I/R injury is associated with an oxidative stress-independent alteration in DDAH activity. These data are a step forward in the understanding of the pathways that regulate serum, tissue, and biliary levels of ADMA in which DDAH enzyme plays a crucial role.

Protective effect of rutin against acute gastric mucosal lesions induced by ischemia-reperfusion

CONTEXT

Rutin, a flavonoid commonly present in onions, apples and tea, has been suggested to have a variety of pharmacological activities, including immunomodulator, anti-inflammatory and antioxidant activities.

OBJECTIVES

The present study was to examine the protective effects of rutin on gastric mucosal damage induced by gastric ischemia-reperfusion (I/R) in rats.

MATERIALS AND METHODS

Rutin (50, 100, 200 mg/kg) was administered intragastrically for five consecutive days before ischemia. Sixty minutes after the last administration of rutin, under anesthesia, the celiac artery was clamped for 30 min, and then the clamp was removed for 60 min reperfusion. After reperfusion, the stomach was removed for biochemical and histological examinations.

RESULTS

As compared with the I/R group (116.7 ± 21.5), administration of rutin at doses of 50, 100 and 200 mg/kg significantly prevented the increase of gastric mucosal injury index induced by gastric I/R (73.4 ± 14.8, 65.9 ± 9.6 and 26.9 ± 5.7, respectively). ED50 value was 138.7 mg/kg. Moreover, rutin at doses of 50, 100 and 200 mg/kg showed an inhibition on the increased myeloperoxidase (24.6, 41.3 and 53.1% reduction) activity and malondialdehyde levels (27.4, 40.3 and 50.7% reduction) in gastric mucosa. Also, the elevation of inducible NO synthase (iNOS) activity as well as the decrease of constitutive NO synthase (cNOS) in the gastric mucosa were significantly prevented by rutin pretreatment.

CONCLUSION

These results suggested that rutin has a protective effect against gastric mucosal injury induced by gastric I/R and that the gastroprotection was related to the NOS/NO pathway and its antioxidant activity.

Inhibition of inducible nitric oxide synthase prevents graft injury after transplantation of livers from rats after cardiac death

This study investigated the roles of inducible nitric oxide synthase (iNOS) in the failure of rat liver grafts from cardiac death donors (GCDD). Livers were explanted after 30-minute aorta clamping and implanted after 4-hour storage in University of Wisconsin solution. The iNOS expression increased slightly in grafts from non-cardiac death donors (GNCDD) but markedly in GCDD. Serum nitrite and nitrate and hepatic 3-nitrotyrosine adducts, indicators of NO and peroxynitrite production, respectively, were substantially higher after transplantation of GCDD than GNCDD. Production of reactive nitrogen species (RNS) was largely blocked by 1400W (N-[1-naphthyl]ethylenediamine dihydrochloride; 5 μM), a specific iNOS inhibitor. Alanine aminotransferase release, bilirubin, necrosis, and apoptosis were 6.4-fold, 6.5-fold, 2.3-fold, and 2.7-fold higher, respectively, after transplantation of GCDD than GNCDD. The inhibitor 1400W effectively blocked these alterations and also increased survival of GCDD to 80% from 33%. Increased RNS production and failure of GCDD were associated with activation of c-Jun-N-terminal kinase (JNK), an effect that was blocked by inhibition of iNOS. Inhibition of JNK also improved the outcome after transplantation of GCDD. Together, the data indicate that iNOS increases substantially in GCDD, leading to RNS overproduction, JNK activation, and more severe graft injury. Inhibitors of iNOS are suggested as effective therapies to improve the outcome after transplantation of GCDD.

Rutin inhibits hydrogen peroxide-induced apoptosis through regulating reactive oxygen species mediated mitochondrial dysfunction pathway in human umbilical vein endothelial cells

Apoptosis of human vein endothelium cell caused by reactive oxygen species is implicated in the pathogenesis of cardiovascular diseases. Rutin, an active flavonoid compound, is well known to possess potent antioxidant properties against oxidative stress insults through undefined mechanism(s). In this study, we first investigated the possible protective effects of rutin against apoptosis of human umbilical vein endothelial cells (HUVECs) induced by hydrogen peroxide (H(2)O(2)) and the associated signaling pathways. Decreased viability and increased apoptosis were observed in the HUVECs incubated with 200microM H(2)O(2) for 12h. By examining the effect of rutin on H(2)O(2)-induced apoptosis in HUVECs, we found that rutin pretreatment significantly attenuated H(2)O(2)-induced apoptosis in HUVECs. We next examined the signaling involved in rutin-mediated anti-apoptotic effects. It was found that rutin pretreatment attenuated excessive reactive oxygen species in HUVECs exposed to H(2)O(2). Rutin also prevented the increased DNA fragment formation and glutathione (GSH) depletion and inhibited the collapse of mitochondrial membrane potentials (DeltaPsim) that occurred in HUVECs exposed to H(2)O(2), which protected HUVECs against oxidative damage and the further mitochondrial membrane integrity impairment, leading to apoptosis. In conclusion, the results suggested that rutin (50microM) blocked apoptosis in HUVECs through decreasing reactive oxygen species, increasing GSH, restoring DeltaPsim and thus protecting DNA damage. Our research indicated that rutin protected the intracellular GSH antioxidant system and prevented H(2)O(2)-induced apoptosis of HUVECs through regulating reactive oxygen species mediated mitochondrial dysfunction pathway.

Antioxidant effects of xanthohumol and functional impact on hepatic ischemia-reperfusion injury

Therapeutic effects of dietary flavonoids have been attributed mainly to their antioxidant capacity. Xanthohumol (1), a prominent flavonoid of the hop plant, Humulus lupulus, was investigated for its antioxidant potential and for its effect on NF-kappaB activation. To examine the biological relevance of 1, a hepatic ischemia/reperfusion model was chosen as a widely accepted model of oxidative stress generation. The impact of 1 on endogenous antioxidant systems, on the NF-kappaB signal transduction pathway as well as on apoptotic parameters, and on hepatic tissue damage was evaluated. Compound 1 markedly decreased the level of reactive oxygen species in vitro. Furthermore, levels of enzymatic and nonenzymatic antioxidants were restored after pretreatment in postischemic hepatic tissue, and lipid peroxidation was attenuated. NF-kappaB activity was reduced in vitro as well as in hepatic tissue after ischemia/reperfusion upon pretreatment with 1. In addition, the phosphorylation of Akt was markedly inhibited. Surprisingly, 1 decreased the expression of the antiapoptotic protein Bcl-X and increased caspase-3 like-activity, a proapoptotic parameter. Moreover, hepatic tissue damage as well as TNF-alpha levels increased in xanthohumol-pretreated liver tissue after ischemia/reperfusion. In summary, xanthohumol did not protect against ischemia/reperfusion injury in rat liver, despite its antioxidant and NF-kappaB inhibitory properties.

Protective effect of rutin on the ischemia/reperfusion induced damage in rat kidney

Reactive oxygen species (ROS) are suggested to participate in ischemia/reperfusion (I/R) injury in the kidney. This study was designed to investigate the effect of rutin, a bioflavonoid, in I/R induced renal injury. Wistar albino rats were unilaterally nephrectomized, and 2 wk later they were subjected to 45 min of left renal pedicle occlusion followed by 3h of reperfusion. Either rutin (1g/kg) or saline was administrated (i.p.) 1h prior to ischemia. At the end of the reperfusion period, kidney samples were taken for determination of renal malondialdehyde (MDA) and glutathione (GSH) levels, manganese-superoxide dismutase (MnSOD) activity and histological examination. Serum creatinine, blood urea nitrogen (BUN), and lactate dehydrogenase (LDH) concentrations were measured for the evaluation of renal function. I/R caused a significant decrease in GSH level and MnSOD activity, which was accompanied by a significant increase in MDA level of kidney tissues. Similarly, serum BUN and creatinine levels, as well as LDH were elevated in the I/R group compared with the control group. Pretreatment of rats with rutin (1g/kg/ i.p.) significantly attenuated renal dysfunction, reduced elevated MDA levels, and restored the depleted MnSOD activity and GSH levels. These beneficial changes in the biochemical parameters were also associated with parallel changes in histopathological appearance. These findings suggest that ROS play a causal role in I/R induced renal injury, and that rutin exerts renal-protective effects, probably by inhibiting ROS and antioxidant activities.