Protective effect of edaravone against hypoxia-reoxygenation injury in rabbit cardiomyocytes

Decreased proteasome function increases oxidative stress in the early stage of pressure ulcer development

The aging process in the elderly results in heightened skin fragility associated with various disorders, including pressure ulcers (PUs). Despite the high incidence of PUs in the elderly population, there is a limited body of research specifically examining the impact of aging on the development of pressure ulcers. Therefore, investigating age-related physiological abnormalities is essential to elucidate the pathogenesis of PUs. Ischemia-reperfusion (I/R) injury and the subsequent oxidative stress caused by reactive oxygen species (ROS) play essential roles in the early stage of PUs. In this study, we used a mouse model of proteasomal dysfunction with an age-related phenotype to examine the role of proteasome activity in cutaneous I/R injury in vivo. Decreased proteasome function did not affect the expression of inflammatory cytokines and adhesion molecules in the I/R area in transgenic mice; however, proteasome inhibition increased oxidative stress that was not attenuated by activation of the oxidative stress response mediated by NF-E2-related factor 2 (Nrf2). In dermal fibroblasts (FCs) subjected to hypoxia-reoxygenation (H/R), proteasome inhibition induced oxidative stress and ROS production, and Nrf2 activation did not adequately upregulate antioxidant enzyme expression, possibly leading to antioxidant/oxidant imbalance. The free radical scavenger edaravone had protective effects against I/R injury in vivo and decreased oxidative stress in FCs treated with a proteasome inhibitor and subjected to H/R in vitro. The results suggest that the age-related decline in proteasome activity promotes cutaneous I/R injury-induced oxidative stress, and free radical scavengers may exert protective effects by preventing oxidative stress in the early stage of PUs.

Intermittent Short-Duration Re-oxygenation Attenuates Cardiac Changes in Response to Hypoxia: Histological, Ultrastructural and Oxidant/Antioxidant Parameters

Context: Intermittent short-duration re-oxygenation attenuates cardiac changes in response to hypoxia.

Objective: To see if intermittent short-duration re-oxygenation may protect the heart muscle from hypoxia damage.

Materials and Methods: Eighteen albino rats were used to carry out the study. Rats divided into: (normoxia); rats exposed to room air as a control, second (hypoxic) group; rats subjected to a pressure of 405 mmHg in a hypobaric chamber to simulate hypoxia at 5,000 m, and third (intermittent short-duration re-oxygenation); rats exposed to room air three times per day. Experiments were all 14 days long.

Results: Hypoxia enhanced the oxidative stress biomarker malondialdehyde while lowering the antioxidant superoxide dismutase . The levels of tumour necrosis factor (TNF-α) and interleukin-6 (IL-6) in the myocardium were elevated in hypoxic hearts. The hypoxic rats’ cardiac myofibrils showed disarray of muscle fibres, vacuolation of the sarcoplasm, pyknosis of the nucleus, and expansion of intercellular gaps on histological examination. In addition, cardiomyocytes showed degenerative defects in ventricular myocardial cells on ultrastructural analysis. Myofibril thinning and degenerative mitochondrial changes affected intercalated discs with fascia adherent, desmosomes, and gap junction. Intermittent short-duration re-oxygenation improve cardiac histological, ultrastructural and oxidant/antioxidant parameters changes during hypoxia.

Conclusion: Hypoxia showed a substantial impact on myocardial architecture, as well as increased oxidative stress and pro-inflammatory cytokines. Intermittent short-duration re-oxygenation significantly decreases hypoxia-induced cardiac changes.

Synthetic/ECM-inspired hybrid platform for hollow microcarriers with ROS-triggered nanoporation hallmarks

Reactive oxygen species (ROS) are key pathological signals expressed in inflammatory diseases such as cancer, ischemic conditions and atherosclerosis. An ideal drug delivery system should not only be responsive to these signals but also should not elicit an unfavourable host response. This study presents an innovative platform for drug delivery where a natural/synthetic composite system composed of collagen type I and a synthesized polythioether, ensures a dual stimuli-responsive behaviour. Collagen type I is an extracellular matrix constituent protein, responsive to matrix metalloproteinases (MMP) cleavage per se. Polythioethers are stable synthetic polymers characterized by the presence of sulphur, which undergoes a ROS-responsive swelling switch. A polythioether was synthesised, functionalized and tested for cytotoxicity. Optimal conditions to fabricate a composite natural/synthetic hollow sphere construct were optimised by a template-based method. Collagen-polythioether hollow spheres were fabricated, revealing uniform size and ROS-triggered nanoporation features. Cellular metabolic activity of H9C2 cardiomyoblasts remained unaffected upon exposure to the spheres. Our natural/synthetic hollow microspheres exhibit the potential for use as a pathological stimuli-responsive reservoir system for applications in inflammatory diseases.

Edaravone enhances the viability of ischemia/reperfusion flaps

The purpose of the experiment was to study the efficacy of edaravone in enhancing flap viability after ischemia/reperfusion (IR) and its mechanism. Forty-eight adult male SD rats were randomly divided into 3 groups: control group (n=16), IR group (n=16), and edaravone-treated IR group (n=16). An island flap at left lower abdomen (6.0 cm×3.0 cm in size), fed by the superficial epigastric artery and vein, was created in each rat of all the three groups. The arterial blood flow of flaps in IR group and edaravone-treated IR group was blocked for 10 h, and then the blood perfusion was restored. From 15 min before reperfusion, rats in the edaravone-treated IR group were intraperitoneally injected with edaravone (10 mg/kg), once every 12 h, for 3 days. Rats in the IR group and control group were intraperitoneally injected with saline, with the same method and frequency as the rats in the edaravone-treated IR group. In IR group and edaravone-treated IR group, samples of flaps were harvested after reperfusion of the flaps for 24 h. In the control group, samples of flaps were harvested 34 h after creation of the flaps. The content of malondialdehyde (MDA) and activity of superoxide dismutase (SOD) were determined, and changes in organizational structure and infiltration of inflammatory cells were observed by hematoxylin-eosin (HE) staining, apoptotic cells of vascular wall were marked by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay, and the apoptotic rate of cells in vascular wall was calculated. The ultrastructural changes of vascular endothelial cells were observed by transmission electron microscopy (TEM). Seven days after the operation, we calculated the flap viability of each group, and marked vessels of flaps by immunohistochemical staining for calculating the average number of subcutaneous vessels. The results showed that the content of MDA, the number of multicore inflammatory cells and apoptotic rate of cells in vascular wall in the edaravone-treated IR group were significantly lower than those in the IR group. The activity of SOD, flap viability and average number of subcutaneous vessels in the edaravone-treated IR group were significantly higher than those in the IR group. All the differences were statistically significant. The ultrastructure injury of vascular endothelial cells in the edaravone-treated IR group was slighter than that in IR group. It was concluded that edaravone can significantly enhance IR flap viability and protect flap vessels, which is related to scavenging oxygen free radicals, reducing the consumption of SOD, reducing the extent of lipid peroxidation and inflammation, and protecting functional structure of vessels in the early stages of reperfusion.

The antioxidant edaravone prevents cardiac dysfunction by suppressing oxidative stress in type 1 diabetic rats and in high-glucose-induced injured H9c2 cardiomyoblasts

Edaravone, a radical scavenger, has been recognized as a potential protective agent for cardiovascular diseases. However, little is known about the effect of edaravone in cardiac complications associated with diabetes. Here, we have demonstrated that edaravone prevents cardiac dysfunction and apoptosis in the streptozotocin-induced type 1 diabetic rat heart. Mechanistic studies revealed that edaravone treatment improved cardiac function and restored superoxide dismutase levels. In addition, treatment of diabetic animals by edaravone increased protein expressions of sirtuin-1 (SIRT-1), peroxisome proliferator activated receptor γ coactivator α (PGC-1α), nuclear factor like-2 (NRF-2), and B cell lymphoma 2 (Bcl-2), and reduced protein expressions of Bax and Caspase-3 compared to the control group. High glucose incubation resulted in the production of reactive oxygen species (ROS) and cell death. Treatment of high-glucose-incubated H9c2 cells by edaravone reduced ROS production and cell death. In addition, the treatment of high-glucose-incubated H9c2 cells by edaravone increased the activity of antioxidative stress by increasing SIRT-1, PGC-1α, and NRF-2, and this treatment also reduced apoptosis by increasing Bcl-2 expression and reducing Bax and Caspase-3 expressions. Knockdown SIRT-1 with small interferer RNA abolished the effects of edaravone. Overall, our data demonstrated that edaravone may be an effective agent against the development of diabetic cardiomyopathy.

Edaravone's free radical scavenging mechanisms of neuroprotection against cerebral ischemia: review of the literature

Free radicals and oxidative stress play key roles in cerebral ischemic pathogenesis and represent pharmacological targets for treatment. Edaravone (Edv), one of antioxidant agents that have been used in acute ischemic stroke in both clinical settings and animal experiments, exerts neuroprotective effect on ischemic injured brains. This review is aimed to elaborate the latest molecular mechanisms of the neuroprotection of Edv on cerebral ischemia and provide reasonable evidence in its clinical application. It is found that Edv has neuroprotective influence on cerebral ischemia, which is closely related to the facets of scavenging reactive oxygen species (ROS), hydroxyl radical (ċOH) and reactive nitrogen species (RNS). And it is a good antioxidant agent that can be safely used in the treatment of cerebral ischemia and chronic neurodegenerative disorders as well as other ischemia/reperfusion (I/R)-related diseases. The combination of Edv with thrombolytic therapy also can be applied in clinical settings and will be greatly beneficial to patients with stroke.

Edaravone inhibits hypoxia-induced trophoblast-soluble Fms-like tyrosine kinase 1 expression: a possible therapeutic approach to preeclampsia

OBJECTIVE

To investigate the effects of edaravone, a potent free radical scavenger used clinically, on hypoxia-induced trophoblast-soluble Fms-like tyrosine kinase 1 (sFlt-1) expression.

METHODS

A trophoblast cell line (HRT-8/SVneo) impaired by cobalt chloride (CoCl2) was used as the cell model under hypoxic conditions. 3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyl tetrazolium bromide (MTT) was used to measure the viability of cells exposed to CoCl2 and edaravone. The levels of intracellular reactive oxygen species (ROS) were analyzed by flow cytometry. mRNA expression of sFlt-1, vascular endothelial growth factor (VEGF), and placental growth factor (PlGF) in trophoblasts was measured by real-time polymerase chain reaction, and the secretion of sFlt-1, VEGF, and PlGF proteins was analyzed by enzyme-linked immunosorbent assays (ELISAs). A human umbilical vein endothelial cell (HUVEC) tube-formation assay was performed to identify the effects of CoCl2 and edaravone on vascular development.

RESULTS

CoCl2 treatment caused the loss of trophoblast viability, the formation of ROS, and sFlt-1 mRNA and protein expression in a dose-dependent manner. Pretreatment with edaravone significantly inhibited hypoxia-induced oxidative stress formation and sFlt-1 expression in trophoblasts. Neither PlGF nor VEGF mRNA or protein expression was increased by CoCl2. In the in vitro tube formation assay, edaravone showed a protective role in vascular development under hypoxic conditions.

CONCLUSION

This study demonstrated that hypoxia leading to increased sFlt-1 release in trophoblasts may contribute to the placental vascular formation abnormalities observed in preeclampsia and suggested that the free radical scavenger edaravone could be a candidate for the effective treatment of preeclampsia.

The efficacy of edaravone (radicut), a free radical scavenger, for cardiovascular disease

Edaravone was originally developed as a potent free radical scavenger, and has been widely used to treat acute ischemic stroke in Japan since 2001. Free radicals play an important role in the pathogenesis of a variety of diseases, such as cardiovascular diseases and stroke. Therefore, free radicals may be targets for therapeutic intervention in these diseases. Edaravone shows protective effects on ischemic insults and inflammation in the heart, vessel, and brain in experimental studies. As well as scavenging free radicals, edaravone has anti-apoptotic, anti-necrotic, and anti-cytokine effects in cardiovascular diseases and stroke. Edaravone has preventive effects on myocardial injury following ischemia and reperfusion in patients with acute myocardial infarction. Edaravone may represent a new therapeutic intervention for endothelial dysfunction in the setting of atherosclerosis, heart failure, diabetes, or hypertension, because these diseases result from oxidative stress and/or cytokine-induced apoptosis. This review evaluates the potential of edaravone for treatment of cardiovascular disease, and covers clinical and experimental studies conducted between 1984 and 2013. We propose that edaravone, which scavenges free radicals, may offer a novel option for treatment of cardiovascular diseases. However, additional clinical studies are necessary to verify the efficacy of edaravone.

Effects of edaravone on the expression of β-defensin-2 mRNA in lung tissue of rats with myocardial ischemia reperfusion

The aim of this study was to investigate the effects of edaravone on lung injury caused by myocardial ischemia reperfusion (I/R) in rats. Wistar rats (n=24) were randomly divided into 4 groups: the sham operation (S group) and myocardial I/R groups (C group) and two edaravone‑treated groups (E1 and E2 groups). Rats in the E1 and E2 groups were injected with 3 or 10 mg/kg edaravone, respectively, 1 min before reperfusion. The rats were sacrificed and the lung tissue, bronchoalveolar lavage (BAL) fluid and serum were obtained. The concentration of serum creatine kinase isoenzyme (CK-MB) was determined, the lung permeability index (PPI) was calculated and β-defensin-2 (BD-2) mRNA expression in the lung tissue and BD-2 and TNF-α protein content levels were determined. Serum CK-MB activity and the PPI were increased, while BD-2 mRNA and BD‑2 and TNF-α protein levels in the lung tissue were upregulated in the C, E1 and E2 groups compared with the S group. The above‑mentioned indicators were decreased in the E1 and E2 groups compared with the IR group. The level of the decrease for indicators in the E2 group was significantly different compared with that in the E1 group. In conclusion, edaravone reduced the lung injury caused by myocardial I/R in rats. Its mechanism of action was not only oxygen free radical scavenging, but was also associated with a suppression of the inflammatory response of the lung tissue.

Edaravone inhibits apoptosis caused by ischemia/reperfusion injury in a porcine hepatectomy model

AIM: To investigate the effect of E3-methyl-1-phenyl-2-pyrazolin-5-one (Edr) on hepatic ischemia-reperfusion (I/R) injury and liver regeneration in a porcine hepatectomy model.

METHODS: One hour ischemia was induced by occluding the vessels and the bile duct of the right and median lobes. A 40% left hepatectomy was performed after reperfusion. Six animals received Edr (3 mg/kg per hour) intravenously and six control animals received saline just before reperfusion. Remnant liver volume, hemodynamics, aspartate aminotransferase (AST), alanine aminotransferase, lactate dehydrogenase and lactic acid, were compared between the groups. The expression of transforming growth factor-β (TGF-β1) and toll-like receptor (TRL) mRNA in hepatic tissues was examined using reverse transcription polymerase chain reaction. Apoptosis was demonstrated by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining, respectively.

RESULTS: Serum AST (P = 0.029), and toll like receptor 4 level (P = 0.043) were significantly lower after 3 h in animals receiving Edr. In addition, TUNEL staining in Edr-treated pigs showed significantly fewer hepatocytes undergoing apoptosis compared with control pigs. After 1 mo, all factors were non-significantly different between the two groups.

CONCLUSION: Edr is considered to reduce hepatic injury in the early stage of I/R injury in a porcine model.

Beyond free radical scavenging: Beneficial effects of edaravone (Radicut) in various diseases (Review)

Free radicals play an important role in the pathogenesis of a variety of diseases; thus, they are an attractive target for therapeutic intervention in these diseases. Compounds capable of scavenging free radicals have been developed for this purpose and some, developed for the treatment of cerebral ischemic stroke, have progressed to clinical trials. One such scavenger, edaravone, is used to treat patients within 24 h of stroke. Edaravone, which can diffuse into many disease-affected organs, also shows protective effects in the heart, lung, intestine, liver, pancreas, kidney, bladder and testis. As well as scavenging free radicals, edaravone has anti-apoptotic, anti-necrotic and anti-cytokine effects in various diseases. Here, we critically review the literature on its clinical efficacy and examine whether edaravone should be considered a candidate for worldwide development, focusing on its effects on diseases other than cerebral infarction. Edaravone has been safely used as a free radical scavenger for more than 10 years; we propose that edaravone may offer a novel treatment option for several diseases.

Identification of oxidized serum albumin in the cerebrospinal fluid of ischaemic stroke patients

BACKGROUND AND PURPOSE

  Extensive evidence has shown that oxidative stress mediates neuronal death in animal models of hypoxic-ischaemia. Brain biomarkers of oxidative stress need to be identified in order to better understand and treat brain damage in human stroke patients. The present study was conducted to identify potential target proteins of oxidative stress in the cerebrospinal fluid (CSF) of stroke patients with acute ischaemic brain injury.

METHODS

  We performed two-dimensional polyacrylamide gel electrophoresis to separate protein samples obtained from the CSF of control and stroke patients. To determine protein oxidation levels, oxyblot was then used to detect protein carbonyls that were determined by formation of a stable 2,4-dinitrophenylhydrazine (DNP) product using an anti-DNP antibody.

RESULTS

  We found that oxidation of serum albumin was increased in the CSF from stroke patients as well as rats who underwent permanent middle cerebral artery occlusion (6.5%, 23%, respectively). In stroke patients, oxidized albumin levels correlated to neurologic indications.

CONCLUSIONS

  The present study suggests that oxidized albumin in CSF can be utilized as an oxidative stress marker in human stroke patients.

Protective effect of edaravone against PrP106-126-induced PC12 cell death

The prion protein peptide PrP106-126 induces cell apoptosis through mechanisms involving production of intracellular reactive oxygen species. The present study investigated the effects of edaravone, a potent free radical scavenger in clinical use, on cell cytotoxicity induced by PrP106-126. Results showed that PrP106-126 decreased PC12 cell viability in a dose- and time-dependent manner. Edaravone significantly antagonized the cytotoxic effects of PrP106-126. Mechanistically, PrP106-126 decreased PC 12 intracellular glutathione (GSH) concentrations, decreased superoxide dismutase (SOD) enzyme activity, increased concentrations of the oxidation end product malondialdehyde (MDA), depolarized the mitochondrial membrane, and increased caspase-3 activity. Edaravone alone did not affect GSH, SOD, or MDA but did effectively reverse all of the intracellular prooxidant effects induced by PrP106-126 and inhibit induced apoptosis in PC12 cells. In conclusion, edaravone may be a viable candidate for the treatment of oxidative stress-induced neurodegenerative disease.

Mitochondrial involvement in cardiac apoptosis during ischemia and reperfusion: can we close the box?

Myocardial ischemia is the main cause of death in the Western societies. Therapeutic strategies aimed to protect the ischemic myocardium have been extensively studied. Reperfusion is the definitive treatment for acute coronary syndromes, especially acute myocardial infarction; however, reperfusion has the potential to exacerbate tissue injury, a process termed reperfusion injury. Ischemia/reperfusion (I/R) injury may lead to cardiac arrhythmias and contractile dysfunction that involve apoptosis and necrosis in the heart. The present review describes the mitochondrial role on cardiomyocyte death and some potential pharmacological strategies aimed at preventing the opening of the box, i.e., mitochondrial dysfunction and membrane permeabilization that result into cell death. Data in the literature suggest that mitochondrial disruption during I/R can be avoided, although uncertainties still exist, including the fact that the optimal windows of treatment are still fairly unknown. Despite this, the protection of cardiac mitochondrial function should be critical for the patient survival, and new strategies to avoid mitochondrial alterations should be designed to avoid cardiomyocyte loss.

Ginsenoside Rg1 protects rat cardiomyocyte from hypoxia/reoxygenation oxidative injury via antioxidant and intracellular calcium homeostasis

Ginsenoside Rg1 is a major active ingredient of Panax notoginseng radix which has demonstrated a number of pharmacological actions including a cardioprotective effect in vivo. This study investigated the protective effect and mechanism of ginsenoside Rg1 in cardiomyocytes hypoxia/reoxygenation (H/R) model. Pretreatment with ginsenoside Rg1 (60-120 microM) reduced lactate dehydrogenase release and increased cell viability in a dose-dependent manner. Fluorescence analysis demonstrated ginsenoside Rg1 reduced intracellular ROS and suppressed the intracellular [Ca(2+)] level. Cell lysate detected an increase of T-SOD, CAT, and GSH levels. The myocardial protection of ginsenoside Rg1 during H/R is partially due to its antioxidative effect and intracellular calcium homeostasis.

Edaravone for the treatment of acute cerebral infarction: role of endothelium-derived nitric oxide and oxidative stress

Thrombolytic therapy is the most effective therapeutic strategy for the prevention of brain injury and reduction of mortality in patients with acute cerebral infarction. A combination of established thrombolytic therapy and effective neuronal protection therapy has more beneficial effects for patients with acute cerebral infarction. Edaravone (chemical name: 3-methyl-1-phenyl-2-pyrazolin-5-one) is a strong, novel scavenger of free radicals. Several lines of evidence have shown that edaravone has preventive effects on brain injury following ischaemia and reperfusion in patients with brain attack. This review focuses on putative mechanisms underlying the beneficial effects of edaravone on the atherosclerotic process in patients with stroke and on the possibility of edaravone-induced extension of the therapeutic time window in patients with acute cerebral infarction.

The novel antioxidant edaravone: from bench to bedside

Over the last decade, important advances have been made to support the fact that reactive oxygen species (ROS) are generated and play a harmful role during the acute and late stages of cerebral ischemia. Several drugs, such as radical scavengers and antioxidants, have been evaluated in preclinical and clinical studies. Edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one; Radicut, Mitsubishi Tanabe Pharma Corporation) is a novel antioxidant that is currently used in Japan for the treatment of patients in the acute stage of cerebral infarction. Edaravone scavenges ROS and inhibits proinflammatory responses after brain ischemia in animals and humans. In particular, postischemic inflammation, leading to brain edema and infarction due to neuronal damage and endothelial cell death, can be ameliorated by edaravone. In addition to these antistroke effects, edaravone has also been shown to prevent oxidative damage to various extracerebral organs. Therefore, in addition to its usefulness in the treatment of stroke, edaravone is expected to play an integral role in the treatment of many oxidative stress-related diseases.

Overexpression of TRPC3 increases apoptosis but not necrosis in response to ischemia-reperfusion in adult mouse cardiomyocytes

An increase in cytosolic Ca2+ via a capacitative calcium entry (CCE)-mediated pathway, attributed to members of the transient receptor potential (TRP) superfamily, TRPC1 and TRPC3, has been reported to play an important role in regulating cardiomyocyte hypertrophy. Increased cytosolic Ca2+ also plays a critical role in mediating cell death in response to ischemia-reperfusion (I/R). Therefore, we tested the hypothesis that overexpression of TRPC3 in cardiomyocytes will increase sensitivity to I/R injury. Adult cardiomyocytes isolated from wild-type (WT) mice and from mice overexpressing TRPC3 in the heart were subjected to 90 min of ischemia and 3 h of reperfusion. After I/R, viability was 51 +/- 1% in WT mice and 42 +/- 5% in transgenic mice (P < 0.05). Apoptosis assessed by annexin V was significantly increased in the TRPC3 group compared with WT (32 +/- 1% vs. 21 +/- 3%; P < 0.05); however, there was no significant difference in necrosis between groups. Treatment of TRPC3 cells with the CCE inhibitor SKF-96365 (0.5 microM) significantly improved cellular viability (54 +/- 4%) and decreased apoptosis (15 +/- 4%); in contrast, the L-type Ca2+ channel inhibitor verapamil (10 microM) had no effect. Calpain-mediated cleavage of alpha-fodrin was increased approximately threefold in the transgenic group following I/R compared with WT (P < 0.05); this was significantly attenuated by SKF-96365. The calpain inhibitor PD-150606 (25 microM) attenuated the increase in both alpha-fodrin cleavage and apoptosis in the TPRC3 group. Increased TRPC3 expression also increased sensitivity to Ca2+ overload stress, but it did not affect the response to TNF-alpha-induced apoptosis. These results suggest that CCE mediated via TRPC may play a role in cardiomyocyte apoptosis following I/R due, at least in part, to increased calpain activation.

Edaravone preserves coronary microvascular endothelial function after ischemia/reperfusion on the beating canine heart in vivo

We examined whether edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one), a free radical scavenger, exerts its protective effect on coronary microvessels after ischemia/reperfusion (I/R) in vivo. Ninety-minute coronary occlusion followed by reperfusion was performed in 16 open-chest dogs with and without edaravone administration. Coronary small artery (> or = 100 microm in size) and arteriolar (< 100 microm) vasodilation, in the presence of endothelium-dependent (acetylcholine) or -independent (papaverine) vasodilators, was directly observed using intravital microscopy before and after I/R. I/R impaired microvascular vasodilation in response to acetylcholine, whereas administration of edaravone preserved the response in microvessels of both sizes, but to a greater extent in the coronary small arteries. No significant changes were noted with papaverine administration. In the edaravone group, the fluorescent intensity from reactive oxygen species (ROS) was lower, whereas nitric oxide (NO) intensity was higher relative to controls in the microvessels of the ischemic area. In conclusion, edaravone preserves coronary microvascular endothelial function after I/R in vivo. These effects, which were NO-mediated, were attributed to the ROS scavenging properties of edaravone.

Preventive and curative effect of edaravone on nerve functions and oxidative stress in experimental diabetic neuropathy

Oxidative stress is implicated as a final common pathway in the development of diabetic neuropathy and pharmacological interventions targeted at inhibiting free radical production have shown beneficial effects. In the present study, we have investigated the effects of edaravone (3 mg/kg; 3-Methyl-1-phenyl-2-pyrazolin-5-one), a free radical scavenger (relatively selective to hydroxyl radicals) in streptozotocin (50 mg/kg i.p.) induced diabetic neuropathy in male Sprague-Dawley rats. Significant reduction (18%) in motor nerve conduction velocity, nerve blood flow (55%) and tail flick latency in cold (53%) and hot (50%) immersion test was observed in diabetic rats compared to age matched non-diabetic rats. Preventive (8 week) and curative (2 week) treatment of edaravone significantly improved the nerve conduction velocity and nociception but not nerve blood flow in diabetic rats. The changes in lipid peroxidation status and anti-oxidant enzymes (Superoxide dismutase and Catalase) levels observed in diabetic rats were significantly restored by edaravone treatment. Increase in blood pressure and vascular resistance was also significantly attenuated by edaravone treatment. This study provides experimental evidence to preventive and curative effect of edaravone on nerve function and oxidative stress in animal model of diabetic neuropathy. Hence edaravone may be tried clinically for the treatment of diabetic neuropathy since it is clinically used in stroke patients.

Susceptibility of brain microvascular endothelial cells to advanced glycation end products-induced tissue factor upregulation is associated with intracellular reactive oxygen species

There is accumulating evidence that advanced glycation end products (AGEs) are relevant to the formation of vascular complications in diabetes mellitus. The aim of this study was to investigate whether AGEs have a significant effect on tissue factor (TF) expression in brain microvascular endothelial cells compared with that in other arterial endothelial cells. Cultured bovine brain microvascular endothelial cells (BBMECs) and aortic endothelial cells (BAECs) were incubated in medium containing glyceraldehyde-derived AGE (glycer-AGE). TF mRNA expression, protein expression, and activity were measured at multiple time points after glycer-AGE incubation. Participation of reactive oxygen species (ROS) in the effect of glycer-AGE on TF expression was investigated by treatment with a free radical scavenger, edaravone, and intracellular ROS measurements with dihydroethidium (DHE). Basic TF mRNA expression was greater in BBMECs than in BAECs. Glycer-AGE significantly upregulated TF mRNA expression in both cells, and the upregulation was more prominent in BBMECs than in BAECs. TF protein expression and activity were also upregulated with a pattern of being greater in BBMECs than in BAECs. Edaravone significantly attenuated the AGE-induced upregulation of TF mRNA expression, protein expression, and activity. Intracellular ROS levels measured with DHE-stained fluorescent intensity were significantly upregulated by glycer-AGE with a pattern of being greater in BBMECs than in BAECs. AGE-induced ROS upregulation was attenuated by edaravone like AGE-induced TF upregulation. These results suggest that brain microvascular endothelial cells are more susceptible to AGE-induced TF upregulation than aortic endothelial cells, and that this susceptibility is associated with levels of intracellular ROS.

MCI-186 (3-Methyl-1-phenyl-2-pyrazolin-5-one) Attenuated Simulated Ischemia/Reperfusion Injury in Cultured Rat Hippocampal Cells

The reactive oxygen species and Ca2+ overload play a critical role in ischemia/reperfusion (I/R) injury. MCI-186 has potent effects in the brain as a free radical scavenger in ischemia-reperfusion. Acute glucose-oxygen deprivation and subsequent reoxygenation were used to model ischemia/reperfusion injury in cultured hippocampal cells. MCI-186 reduced malondialdehyde level and raised the SOD activity when applied upon reoxygenation in a dose-dependent manner compared with the untreated group. The peak neuroprotective effects occurred at 100 and 300 microM. Intracellular free calcium concentration ([Ca2+]i) was significantly reduced in the 100 microM MCI-186-treated group compared to the untreated group (32.5+/-4.0 versus 50.2+/-3.6, p<0.01). Treatment with 100 microM MCI-186 significantly inhibited the decrease of mitochondria membrane potential after simulated ischemia/reperfusion (204+/-11.6% compared with the untreated group, p<0.01). Cell apoptotic rate was significantly decreased following MCI-186 treatment from 33.7+/-2.3% (untreated group) to 16.6+/-1.4% (100 microM MCI-186 treated group). There was no significantly protective difference between 100 and 300 microM MCI-186. MCI-186 effectively protects neuron injury after simulated ischemia/reperfusion by inhibiting lipid peroxidation, reducing Ca2+ overload, elevating mitochondria membrane potential, and decreasing apoptosis.