Protective Effect Of Edaravone Research Articles

Edaravone protects rats and human pulmonary alveolar epithelial cells against hyperoxia injury: heme oxygenase-1 and PI3K/Akt pathway may be involved

ABSTRACTPurpose/Aim: Hyperoxic acute lung injury (HALI) is a clinical syndrome as a result of prolonged supplement of high concentrations of oxygen. As yet, no specific treatment is available for HALI. The present study aims to investigate the effects of edaravone on hyperoxia-induced oxidative injury and the underlying mechanism. Materials and Methods: We treated rats and human pulmonary alveolar epithelial cells with hyperoxia and different concentration of edaravone, then examined the effects of edaravone on cell viability, cell injury and two oxidative products. The roles of heme oxygenase-1 (HO-1) and PI3K/Akt pathway were explored using Western blot and corresponding inhibitors. Results: The results showed that edaravone reduced lung biochemical alterations induced by hyperoxia and mortality of rats, dose-dependently alleviated cell mortality, cell injury, and peroxidation of cellular lipid and DNA oxidative damage. It upregulated cellular HO-1 expression and activity, which was reversed by PI3K/Akt pathway inhibition. The administration of zinc protoporphyrin-IX, a HO-1 inhibitor, and LY249002, a PI3K/Akt pathway inhibitor, abolished the protective effects of edaravone in cells. Conclusions: This study indicates that edaravone protects rats and human pulmonary alveolar epithelial cells against hyperoxia-induced injury and the antioxidant effect may be related to upregulation of HO-1, which is regulated by PI3K/Akt pathway.

Protective Effect of Edaravone in Primary Cerebellar Granule Neurons against Iodoacetic Acid-Induced Cell Injury.

Edaravone (EDA) is clinically used for treatment of acute ischemic stroke in Japan and China due to its potent free radical-scavenging effect. However, it has yet to be determined whether EDA can attenuate iodoacetic acid- (IAA-) induced neuronal death in vitro. In the present study, we investigated the effect of EDA on damage of IAA-induced primary cerebellar granule neurons (CGNs) and its possible underlying mechanisms. We found that EDA attenuated IAA-induced cell injury in CGNs. Moreover, EDA significantly reduced intracellular reactive oxidative stress production, loss of mitochondrial membrane potential, and caspase 3 activity induced by IAA. Taken together, EDA protected CGNs against IAA-induced neuronal damage, which may be attributed to its antiapoptotic and antioxidative activities.

Edaravone decreases paraquat toxicity in a549 cells and lung isolated mitochondria.

Edaravone, an antioxidant and radical scavenger, showed protective effects against oxidative stress-like condition. Paraquat (PQ) is toxic herbicide considerable evidence suggests that oxidative stress and mitochondrial dysfunction contribute to PQ toxicity. In this study, protective effect of edaravone against PQ induced toxicity and reactive oxygen species (ROS) generation in A549 cells and lung isolated mitochondria were evaluated. A549 cells and lung isolated mitochondria were divided into control group, PQ group, edaravone group and PQ plus edaravone-pretreated group. Cellular and mitochondrial viability assayed using MTT test and ROS generations in both cellular and mitochondrial fraction were determined by fluorometry using DCFH-DA as indicator. Our results showed that edaravone (5-100 µM) prevented PQ (500 µM) induced cytotoxicity in A549 cells that the best protective effect was observed at concentration of 50 µM of edaravone. In addition, PQ-induced ROS generation in A549 cells significantly inhibited by edaravone. Moreover, PQ decreased mitochondria viability and also increased ROS generation in lung isolated mitochondria that edaravone (25-400 µM) markedly inhibited these toxic effects. In overall, the results of this study suggest that lung mitochondria maintenance is essential for maintaining PQt cytotoxicity and Edaravone is a protective drug against PQ toxicity in-vitro.

Edaravone Protected Human Brain Microvascular Endothelial Cells from Methylglyoxal-Induced Injury by Inhibiting AGEs/RAGE/Oxidative Stress

Subjects with diabetes experience an increased risk of cerebrovascular disease and stroke compared with nondiabetic age-matched individuals. Increased formation of reactive physiological dicarbonyl compound methylglyoxal (MGO) seems to be implicated in the development of diabetic vascular complication due to its protein glycation and oxidative stress effect. Edaravone, a novel radical scavenger, has been reported to display the advantageous effects on ischemic stroke both in animals and clinical trials; however, little is known about whether edaravone has protective effects on diabetic cerebrovascular injury. Using cultured human brain microvascular endothelial cells (HBMEC), protective effects of edaravone on MGO and MGO enhancing oxygen-glucose deprivation (OGD) induced injury were investigated. Cell injury was measured by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) formation, cell account, lactate dehydrogenase (LDH) release and Rhodamine 123 staining. Advanced glycation end-products (AGEs) formation and receptor for advanced glycation end-products (RAGE) expression were measured by western blotting. Cellular oxidative stress was measured by reactive oxygen species (ROS) release. Treatment of MGO for 24 h significantly induced HBMEC injury, which was inhibited by pretreatment of edaravone from 10–100 µmol/l. What’s more, treatment of MGO enhanced AGEs accumulation, RAGE expression and ROS release in the cultured HBMEC, which were inhibited by 100 µmol/l edaravone. Finally, treatment of MGO for 24 h and then followed by 3 h OGD insult significantly enhanced cell injury when compared with OGD insult only, which was also protected by 100 µmol/l edaravone. Thus, edaravone protected HBMEC from MGO and MGO enhancing OGD-induced injury by inhibiting AGEs/RAGE/oxidative stress.

The protective effects of edaravone combined with ulinastatin on the treatment of brain injury in rats with severe acute pancreatitis

Objective To investigate the protective effects of edaravone combined with ulinastatin on the treatment of brain injury in rats with severe acute pancreatitis.Methods A total of 100 male Sprague-Dawley rats were randomly divided into 10 groups that consisted of a normal control 6 and 48 hour group,a SAP 6 and 48 hour group,an edaravone treated 6 and 48 hour group,a ulinastatin treated 6 and 48 hour group,and finally a combination of edaravone and ulinastatin treated 6 and 48 hour group.Each group included 10 rats.Neurobehavioral scores were observed and a series of blood,pancreatic tissue,and brain tissue samples were obtained at 6 and 48 hours after operation.Serum amylase,brain tissue Evans Blue content,brain tissue water content,and the histopathological change of the pancreas and brain tissues were observed.Serum TNF-α was detected by RIA.The TNF-α mRNA and nuclear factor kappa B(NF-κB) p65 activity in brain tissues were measured with RT-PCR and immunohistochemistry,respectively.Results In contrast to the 48 hour SAP,edaravone treated,and ulinastatin treated groups,the serum amylase,brain tissue Evans Blue content,brain tissue water content,histopathological score of the rat pancreas and brain tissue,serum TNF-a,TNF-a mRNA,and NF-κB p65 activity in brain tissues significantly decreased while neurobehavioral scores significantly increased in the 48 hour combined edaravone and ulinastatin treatment group (P＜0.01).Conclusion Edaravone combined with ulinastatin can play a protective role on brain injury in rats with severe acute pancreatitis. Key words: Edaravone; Ulinastatin; Pancreatitis, acute necrotizing; Brain injury

Protective effects of edaravone against cisplatin-induced hair cell damage in zebrafish

ObjectiveEdaravone is known to have a potent free radical scavenging effect. The objective of the present study was to evaluate the effects of edaravone on cisplatin-induced ototoxicity in transgenic zebrafish (Brn3C: EGFP). MethodsFive day post-fertilization zebrafish larvae were exposed to 1000μM cisplatin and 50μM, 100μM, 250μM, 500μM, 750μM, and 1000μM concentrations of edaravone for 4h. Hair cells within neuromasts of the supraorbital (SO1 and SO2), otic (O1), and occipital (OC1) lateral lines were analyzed by fluorescence microscopy and confocal microscopy (n=10). Hair cell survival was calculated as a percentage of the hair cells in the control group that were not exposed to cisplatin. Ultrastructural changes were evaluated using scanning electron microscopy and transmission electron microscopy. ResultsEdaravone protected cisplatin-induced hair cell loss of neuromasts (edaravone 750μM: 8.7±1.5 cells, cisplatin 1000μM only: 3.7±0.9 cells; n=10, p<0.0001) and decreased the Terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labeling (TUNEL) reaction. Structures of mitochondria and hair cell within neuromasts in ultrastructural analysis were preserved in zebrafish exposed to 1000μM cisplatin and 750μM edaravone for 4h. ConclusionsEdaravone attenuated cisplatin-induced hair cell damage in zebrafish. The results of the current study suggest that cisplatin induces apoptosis, and the apoptotic cell death can be prevented by treatment with edaravone in zebrafish.

Protective effects of edaravone on experimental chronic pancreatitis induced by dibutyltin dichloride in rats

Background/aimsTo investigate the effects of edaravone, a potent free radical scavenger, on dibutyltin dichloride (DBTC)-induced chronic pancreatitis (CP) and pancreatic fibrosis. MethodsMale Sprague–Dawley rats were randomly divided into four groups (n = 16 each): control, DBTC, DBTC + edaravone, and control + edaravone. Edaravone or normal saline at a daily dose of 6 mg/kg body weight was given intraperitoneally from day 5 to day 28 after DBTC administration. On days 14 and 28, the rats were evaluated morphologically and biochemically. The expression of cytokines in pancreas TGF-β, IL-6 and TNF<alpha> was detected using RT-PCR. The activation of nuclear factor (NF)-κB in pancreatic tissue was evaluated by immunostaining and western-blot for NF-κB p65. α-smooth muscle actin (α-SMA) expression was also evaluated by immunostaining and western-blot to investigate the activation of pancreatic stellate cells (PSCs). ResultEdaravone treatment improved the rats' body weight (p < 0.01) and feed intake levels (p < 0.05), improved the histological scores and alleviated the fibrosis of pancreas samples (p < 0.05), as well as markedly increased superoxide dismutase (SOD) activity and decreased malondialdehyde (MDA) concentrations in pancreatic tissue (p < 0.01 for both). The expression of cytokines TGF-β, IL-6 and TNF<alpha> in pancreas of DBTC group was also down-regulated by edaravone after treatment. Edaravone inhibited the activation of NF-κB and PSCs and exhibited protective effects on pancreatic tissue damage in CP. ConclusionsThis antioxidant may be a promising therapeutic intervention for human CP.

Protective effect of edaravone on corneal nerve of rat with experimental diabetic corneal neuropathy

Background With the number of diabetics increases,people pay more attention to the diabetic keratopathy.The major mechanism leading to diabetic keratopathy is diabetic corneal neuropathy.So it is significant to observe pathologic mechanism of diabetic corneal neuropathy. Objective To investigate the protective effects of edaravone( a free radical scavenger) on corneal nerve of rats with experimental diabetic corneal neuropathy,then explain the effects of oxidative stress in the pathologic mechanism of diabetic corneal neuropathy. Methods Seventy Sprague-Daxley male rats were taken as experimental subjects and 20 of them were used as normal control group.The remaining 50 were induced to be diabetic mellitus by a single intraperitoneal injection of streptozotocin and divided into 2 groups randomly:edaravone treated group and diabetic control group.In the edaravone treated group,edaravone(0.2 g/L) eye drops were used 3 times a day until the animal was killed.Five rats in each group were sacrificed at 6,8,10 and 12 weeks respectively.Then the corneal sensation,number of corneal nerve fibers,morphology,content of malondialdehyde(MDA) and activity of superoxide dismutase(SOD) in the corneal tissue were detected. Results In the diabetic control group,the corneal sensation and the number of corneal nerve fibers were decreased,the density of neural network for cluster was sparse,the nerve activity was decreased,the content of MDA in the corneal tissue was significantly increased,the activity of SOD in the corneal tissue was significantly decreased (P＜0.01 ).Accompany with the course of disease,the above change was obvious day after day.Compared with the diabetic control group,the corneal sensation and the morphological abnormalities in corneal nerve of edaravone group were improved significantly which had the partial branches to the 12th week,the content of MDA in the corneal tissue was significantly decreased,the activity of SOD in the corneal tissue was significantly increased (P＜0.01).Conclusions Edaravone can lower diabetic corneal nerve of rats with experimental diabetic corneal neuropathyinjury,Oxidative stress may be a critical pathologic mechanism of diabetic corneal neuropathy. Key words: Edaravone; Diabetic corneal neuropathy; Corneal nerve; Oxidative stress; Pathologic mechanism

Effects of Edaravone, a Free Radical Scavenger, on Serum Levels of Inflammatory Biomarkers in Acute Brain Infarction

The potent free radical scavenger edavarone is widely used in Japan to treat acute ischemic stroke within 24 hours after onset. Recent experimental studies have shown that edavarone alleviates blood-brain barrier disruption in conjunction with suppression of the inflammatory reaction in acute brain ischemia. We investigated the effects of edaravone on circulating inflammatory biomarkers in patients with ischemic stroke. Patients with acute ischemic stroke admitted 12-36 hours after onset of symptoms were prospectively enrolled. Intravenous edaravone at 60 mg/day for 14 days was administered to patients admitted 12-24 hours after symptom onset (edaravone group; n = 29). Patients admitted 24-36 hours after onset served as controls (control group; n = 34). Venous blood samples were obtained on admission and at 48 hours, 7 days, and 14 days after symptom onset. Serum concentrations of high-sensitivity C-reactive protein, interleukin (IL)-6, IL-10, IL-18, tumor necrosis factor α, matrix metalloproteinase (MMP)-2, and MMP-9 were measured. General linear models were used to compare changes in concentrations of these biomarkers over time between the groups. In the control group, the mean MMP-9 concentration increased gradually from 3.857 ± 1.880 ng/mL to 4.538 ± 1.966 ng/mL over the 14-day period (P = .027, one-way repeated-measures analysis of variance [ANOVA]), but the edavarone group demonstrated no such increase (P = .564). A significant group-time interaction was demonstrated only for MMP-9 (P = .029, two-way repeated-measures ANOVA), and no significant differences in other biomarkers were seen between groups. Our data indicate that edaravone suppresses serum MMP-9 level in patients with acute ischemic stroke. Further studies with a larger sample size are needed to explore the relationship between circulating MMP-9 level and the protective effect of edaravone.

Protective effects of edaravone on diffuse brain injury in rats.

Edaravone can alleviate brain injury and improve neurological functions and symptoms. This study aimed to investigate the effect of edaravone on the p38Mitogen-activated protein kinases/Caspase-3 (p38MAPK /Caspase-3) pathway after diffuse brain injury (DBI) in rats. DBI models were established according to the description of Marmarou's method. A total of 250 rats were divided (random number) into four groups: control group (CG, n=45), model group (MG, n=77), low-dose edaravone group (n=67, dosage 5 mg/kg) and high-dose edaravone group (n=61, dosage 10 mg/kg). After 1, 6, 24, 48, and 72 hours after injury, brain tissues were collected. The changes of neuron morphous in the hippocampal region were observed through Nissl staining. The expression levels of phosphorylated p38MAPK and caspase-3 were detected by immunohistochemistry and Western blotting respectively. Learning and memory function were tested with Morris water maze from the 3rd to 7th day after injury. Some neurons had histopathologic changes of necrosis and apoptosis in the model group compared with the control group. The phosphorylated p38MAPK expressions increased at 1, 6, 4, and 48 hours (P<0.05), but no significant difference was observed at 72 hours (0.54±0.19 vs. 0.40±0.14, P>0.05). Caspase-3 expressions increased at 6, 24, 48, and 72 hours respectively (P<0.05), but there was no significant difference at 1 hour (0.59±0.29 vs. 0.40±0.17, P>0.05). From the 3rd to 6th day during the Morris water maze test, the latency to find the platform was significantly prolonged (P<0.05) and times of rats crossing the platform was decreased on the 7th day (2.28±1.18 vs. 8.20±1.52, P<0.05). The phosphorylated p38MAPK expressions decreased at 6, 24 and 48 hours respectively in the low dose edaravone group compared with the model group (P<0.05), whereas no significant difference was seen at 1 hour (1.66±0.80 vs. 1.85±0.86, P>0.05). Caspase-3 expression decreased at 6, 24, 48, and 72 hours (P<0.05). The latency to find the platform was significantly shortened (P<0.05), and times of rats crossing the platform increased (4.17±1.15 vs. 2.28±1.18, P<0.05). The above mentioned parameters changed more significantly in the high-dose edaravone group than in the low-dose edaravone group. Edaravone can alleviate brain tissue damage after DBI, inhibit p38MAP signal activation after early injury, reduce the expression of caspase-3, and promote the recovery of neurological function in the late period.

Protective effects of Edaravone on the diffuse injury of brain in rats

Objective To investigate the effects of Edaravone （Ed） on p38mitogen-activated protein kinases/Caspase-3 （p38MAPK/Caspase-3） pathway following the diffuse injury of brain （DIB） in rats, as well as the protective effects of Edaravone on traumatic injury of brain （TIB）. Method The TIB models were established by using Marmarou＇s method in adult male Spraque-Dawlley rats. A total of 250 rats were divided （random number）9nto control group, model group, low-dose Edaravone treatment group and high-dose Edaravone treatment group.The rats were sacrificed separately 1, 6, 24, 48 and 72 hours after DIB and the brain tissues of rats were taken.The morphological changes of neuron in hippocampus region were observed by using Nissl staining. The levels of phosphorylated p38MAPK and Caspase-3 were detected by using immunohistochemistry and Western blot. The learning and memory functions were determined with Morris water maze test from the 3rd to 7th day after injury.Results Compared with control group, some neurons displayed histopathological changes of necrosis and apoptosis in rats of model group. The levels of phosphorylated p38MAPK significantly increased in 1, 6, 24, and 48 hours after injury in rats of model group （ P 〈 0.05）, but there was no statistic significance in increase 72 hours later （ P〉 0.05）. The levels of Caspase-3 significantly increased in 6, 24, 48 and 72 hours after injury in rats of model group （ P 〈 0.05）, but there was no significant difference in increase in one hour after injury （0.59±0.29 vs.0.40±0.17, P 〉0.05）.In the Morris water maze test from the 3rd to 6th day, the latency to find the platform significantly prolonged in rats of model group （ P 〈 0.05）, and the numbers of passing the platform by rats decreased on the 7th day （2.28 ± 1.18 vs. 8.20 ± 1.52, P 〈 0.05）. Compared with model group, the levels of phosphorylated p38MAPK in 6, 24 and 48 hours after injury in low-dose Edaravone group were lower （P 〈0.05）, but there was no statistical difference in one hour after injury （ P 〉 0.05）. The levels of Caspase-3 in 6,24, 48 and 72 hours after injury in rats of low-dose Edaravone group were lower than those of model group （ P 〈0.05）. The latency to find the platform significantly shortened （ P 〈 0.05） and the numbers of passing the platform by rats increased （4.17 ± 1.15 vs. 2.28 ± 1.18, P 〈 0.05） in low-dose Edaravone group. The above variables changed more prominently in high-dose Edaravone group. Conclusions Edaravone attenuates p38MAPK pathway activation, lowers the level of Caspase-3 following DIB and protects the rats against the traumatic injury of brain. Key words: Rats; Traumatic brain injury; Mitogen-activated protein kinases; Caspase-3; Learning-memory

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.

Protective effect of edaravone, a free‐radical scavenger, on ischaemia‐reperfusion injury in the rat testis

To investigate the effect of edaravone, a radical scavenger, on ischaemia-reperfusion (I-R) injury in the testes. Eight-week-old male Sprague-Dawley rats were allocated to one of four groups: a no-drug group subjected to induction of 30-min of ischaemia and 60-min reperfusion; two drug groups administered edaravone at 1 or 10 mg/kg intraperitoneal and then subjected to 30-min ischaemia and 60-min reperfusion; and a sham-operated control group administered edaravone at 10 mg/kg intraperitoneal. To induce testicular I-R, the right testis was exposed outside of the body and the testicular artery was clamped with a small clip for 30 min. Blood flow and nitric oxide (NO) release were monitored in real time simultaneously with a laser Doppler flowmeter and an NO-selective electrode, respectively. After death the tissue levels of NO(2)-NO(3) (a marker of NO production), malondialdehyde (a marker of lipid peroxidation), 8-hydroxydeoxyguanosine (a marker of oxidative DNA damage), myeloperoxidase (a marker of neutrophil infiltration), and heat-shock protein 70 (HSP 70) and its mRNA were measured. The testicular tissue was also analysed histologically. Clamping the testicular artery resulted in a decrease of blood flow to 0-5% of the basal level measured before clamping. NO release was increased during clamping and gradually recovered to the basal level on removing the clip. Interestingly, the peak of NO release in rats of the no-drug group occurred at the start of reperfusion, while that in the high-dose drug group occurred several minutes later. The levels of NO(2)-NO(3), malondialdehyde, 8-hydroxydeoxyguanosine, myeloperoxidase and HSP 70 and its mRNA, and histological variables, were significantly greater in the no-drug I-R group than in the control, and these variables were ameliorated by treatment with edaravone. These results indicate that edaravone reduces the oxidative stress and prevents the testicular damage induced by I-R.

Protective effects of edaravone against cobalt chloride-induced apoptosis in PC12 cells

To investigate the neuroprotective effects of edaravone (Eda) on cobalt chloride (CoCl2)-induced oxidative stress and apoptosis in cultured PC12 cells as well as the underlying mechanisms. PC12 cells impaired by CoCl2 were used as the cell model of hypoxia. MTT (methyl thiazolyl tetrazolium) was used to assay the viability of the PC12 cells exposed to Eda with gradient concentrations; Hochest 33258 stain assay was used to analyze the apoptosis ratio of the PC12 cells; Bcl-2 and Bax protein levels in PC12 cells were examined by western blotting. ROS level, the mitochondrial transmembrane potential and caspase-3 activity in each group were detected by spectrofluorometer. CoCl2 treatment caused the loss of cell viability in PC12 cells, which was associated with the elevation of apoptotic rate, the formation of ROS and the disruption of mitochondrial transmembrane potential. CoCl2 also significantly induced the upregulation of Bax/Bcl-2 ratio and the activation of caspase-3. In contrast, Eda significantly reversed these phenotypes, with its maximum protective effect at 0.1 micromol/L. These results indicated that Eda could protect PC12 cells from CoCl2-induced cytotoxicity, and this protection might be ascribed to its anti-oxidative and anti-apoptotic activities.

Protective effects of edaravone on rats with severe acute pancreatitis

Protective effects of edaravone on rats with severe acute pancreatitis

Protective effect of edaravone against tobramycin-induced ototoxicity

Conclusion. It is suggested that simultaneous treatment with the radical scavenger edaravone has an effective protective effect against tobramycin ototoxicity in rat. Even if the edaravone treatment is postponed for 7 days, it can still prevent hearing loss, but a 14 day delay cannot protect from ototoxicity. Objectives. With the aim of alleviating hearing loss caused by aminoglycoside ototoxicity, we performed a trial to assess the hearing protective efficacy of the radical scavenger edaravone. Materials and methods. In part one of the study, 21 male Sprague-Dawley albino rats were used; 2 rats served as controls for the safety of edaravone. Eight rats each received 10 subcutaneous injections (s.c.) of tobramycin (160 mg/kg b.w.) once daily and saline injection intraperitoneally for 2 weeks. Eleven rats were given 10 s.c. tobramycin injections simultaneously with an intraperitoneal injection of edaravone (3 mg/kg b.w.). In part two, tobramycin was injected in 13 rats (as above). Five of these received two edaravone injections 7 days later and four rats similarly 14 days later. Auditory brainstem response (ABR) was used to assess hearing. Results. All rats treated only with tobramycin showed a deterioration of hearing. None of the rats given simultaneous treatment with tobramycin and edaravone demonstrated hearing loss. A 7 day delay in edaravone injection still prevented hearing loss, but a 14 day delay had only a temporary prophylactic effect.

The free-radical scavenger edaravone restores the differentiation of human neural precursor cells after radiation-induced oxidative stress

Recently, it has been elucidated that cognitive dysfunction following cranial radiotherapy might be linked to the oxidative stress-induced impairment of hippocampal neurogenesis that is mediated by proliferating neural stem or progenitor cells. The novel free-radical scavenger edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one) has been clinically used to reduce neuronal damage following ischemic stroke. Here, we demonstrate via in vitro studies that edaravone protects human neural stem cells (NSCs) from cell death and restores their differentiation ability after irradiation; however, the protective effect of edaravone is not observed in human brain tumor cells. Our study may shed some light on the beneficial effects of free-radical scavengers in impaired neurogenesis following cranial radiation therapy.

Protective effect of edaravone against endolymphatic hydrops

Conclusion. Our findings suggest that edaravone prevented the production of reactive oxygen species (ROS). Edaravone also delayed the formation of endolymphatic hydrops in guinea pigs, but had no effect on endolymphatic hydrops. Objective. To analyse the protective effect of a free radical scavenger, edaravone, on endolymphatic hydrops. Materials and methods. Guinea pigs were subjected to surgical obliteration of the endolymphatic duct (ED). For the detection of ROS, group 1 received intraperitoneal injections of edaravone (3 mg/kg/day) for 2 days, group 2 received edaravone for 2 weeks, group 3 saline for 2 days, and group 4 saline for 2 weeks. ROS production by the organ of Corti and stria vascularis was examined by using dihydrotetramethylrosamine. For the morphological analysis, guinea pigs were divided into five groups, i.e. 2 or 4 weeks after ED obliteration, 2 weeks with edaravone, first or last 2 weeks with edaravone and sacrificed 4 weeks after ED obliteration. Increases in the ratios of the cross-sectional area of scala media were analysed quantitatively to assess the degree of endolymphatic hydrops among the above-mentioned five groups of the hydropic cochlea. Results. ROS was detected both in the organ of Corti and in the lateral wall of cochleae 2 days after ED obliteration. Edaravone prevented the production of ROS and also attenuated the formation of endolymphatic hydrops in the acute hydrops group.

Protective effect of edaravone in inner-ear barotrauma in guinea pigs

The purpose of this study was to determine the protective effect of edaravone, a free radical scavenger, on inner-ear barotrauma (IEB) in guinea pigs, based on a hypothesis implicating free radicals in the development of IEB. One hundred and twenty-five guinea pigs were divided into a control group and a pretreatment group. After auditory brainstem response (ABR) testing, the pretreatment group received 9.0 mg/kg intraperitoneal edaravone. Animals were exposed to pressure loading and then to further ABR testing. The incidence of IEB was 62.7 per cent in the control group and 42.9 per cent in the pretreatment group (p<0.01). The distributions of threshold elevation in the control group were 37.3 per cent (for 10 dB or less), 21.3 per cent (for 20-30 dB), 18.0 per cent (for 40-60 dB) and 23.4 per cent (for 70 dB or more), and those in the pretreatment group were 57.1 per cent, 19.1 per cent, 14.3 per cent and 9.5 per cent, for the same respective decibel levels (p<0.01). These results suggest that protective treatment with edaravone can significantly reduce both the incidence of IEB and the severity of the resultant ABR threshold elevation.

Protective effect of edaravone against the ototoxicity of Pseudomonas aeruginosa exotoxin A

Conclusion. Our findings suggest that edaravone can protect against cochlear damage caused by Pseudomonas aeruginosa exotoxin A (PaExoA). Objective. To analyze the protective effect of a free radical scavenger, edaravone, against the ototoxicity resulting from exposure of the middle ear to PaExoA. Material and methods. In nine groups of albino rats the following solutions were instilled either via the tympanic membrane into the round window niche [intratympanically (i.t.)] or intravenously (i.v.): edaravone (i.v.); edaravone (i.t.); PaExoA (i.t.) + edaravone (i.t.; simultaneously); PaExoA (i.t.) + edaravone (i.t.; 1 h after); PaExoA (i.t.) + edaravone (i.t.; 24 h after); PaExoA (i.t.) + edaravone (i.v.; simultaneously); PaExoA (i.t.) + edaravone (i.v.; 1 h after); PaExoA (i.t.) + edaravone (i.v.; 24 h after); PaExoA (i.t.) + saline (i.v.). Frequency-specific (2–20 kHz) auditory brainstem responses were measured to determine hearing thresholds before and 2, 5 and 10 days after instillation. Results. PaExoA had penetrated from the middle ear into the cochlea and caused hearing loss. This impairment was blocked by intratympanic injection of edaravone when given simultaneously or 1 h after the first instillation of PaExoA, or by intravenous injection of edaravone when given simultaneously. There were significant differences in protective effect between the intratympanic and intravenous routes.