Edaravone inhibits JNK-c-Jun pathway and restores anti-oxidative defense after ischemia-reperfusion injury in aged rats

Edaravone Dexborneol Alleviates Cerebral Ischemic Injury via MKP-1-Mediated Inhibition of MAPKs and Activation of Nrf2

The edaravone and dexborneol concentrated solution for injection (edaravone-dexborneol) is a medication used clinically to treat neurological impairment induced by ischemic stroke. This study was aimed at investigating the preventive effects and the underlying mechanisms of edaravone-dexborneol on cerebral ischemic injury. A rat four-vessel occlusion (4-VO) model was established, and the neuronal injury and consequent neurological impairment of rats was investigated. Brain tissue malondialdehyde (MDA), myeloperoxidase (MPO), and nitric oxide (NO) levels were determined. The levels of proteins in mitogen-activated protein kinases (MAPKs), nuclear factor erythroid 2-related factor 2 (Nrf2), and nuclear factor-κB (NF-κB) signaling pathways were determined by western immunoblotting. The function of mitogen-activated protein kinase phosphatase 1 (MKP-1) was investigated using both western blot and immunofluorescence methods, and the effect of the MKP-1 inhibitor, (2E)-2-benzylidene-3-(cyclohexylamino)-3H-inden-1-one (BCI), was investigated. The results indicated that edaravone-dexborneol alleviated neurological deficiency symptoms and decreased apoptosis and neuron damage in the hippocampal CA1 area of the ischemic rats. Edaravone-dexborneol increased the MKP-1 level; decreased the phosphorylation of extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p38 mitogen-activated protein kinase (p38 MAPK); inhibited NF-κB p65 activation; and boosted Nrf2 activation, all of which were partially reversed by the MKP-1 inhibitor, BCI. The above results indicated that the upregulation of MKP-1 contributed to the protective effects of edaravone-dexborneol against ischemic brain injury. Our findings support the hypothesis that edaravone-dexborneol can alleviate cerebral ischemic injury via the upregulation of MKP-1, which inhibits MAPKs and activates Nrf2.

Exploration of the mechanism of luteolin against ischemic stroke based on network pharmacology, molecular docking and experimental verification

Stroke is a leading cause of morbidity and mortality worldwide. As the most common type of stroke cases, treatment effectiveness is still limited despite intensive research. Recently, traditional Chinese medicine has attracted attention because of potential benefits for stroke treatment. Among these, luteolin, a natural plant flavonoid compound, offers neuroprotection following against ischemic stroke, although the specific mechanisms are unknown. Here we used network pharmacology, molecular docking, and experimental verification to explore the mechanisms whereby luteolin can benefit stroke recovery. The pharmacological and molecular properties of luteolin were obtained from Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform. The potential targets of luteolin and ischemic stroke were collected from interrogating public databases. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses were performed by Funrich and Database for Annotation, Visualization and Integrated Discovery respectively, a luteolin-target-pathway network constructed using Cytoscape, Autodock vina was used for molecular docking simulation with Discovery Studio was used to visualize and analyze the docked conformations. Lastly, we employed an in vitro model of stroke injury to evaluate the effects of luteolin on cell survival and expression of the putative targets. From 95 candidate luteolin target genes, our analysis identified six core targets . KEGG analysis of the candidate targets identified that luteolin provides therapeutic effects on stroke through TNF signaling and other pathways. Our experimental analyses confirmed the conclusions analyzed above. In summary, the molecular and pharmacological mechanisms of luteolin against stroke are indicated in our study from a systematic perspective.

Drug Repurposing: Promises of Edaravone Target Drug in Traumatic Brain Injury

Edaravone is a potent free-radical scavenger that has been in the market for more than 30 years. It was originally developed in Japan to treat strokes and has been used there since 2001. Aside from its anti-oxidative effects, edaravone demonstrated beneficial effects on proinflammatory responses, nitric oxide production, and apoptotic cell death. Interestingly, edaravone has shown neuroprotective effects in several animal models of diseases other than stroke. In particular, edaravone administration was found to be effective in halting amyotrophic lateral sclerosis (ALS) progression during the early stages. Accordingly, after its success in Phase III clinical studies, edaravone has been approved by the FDA as a treatment for ALS patients. Considering its promises in neurological disorders and its safety in patients, edaravone is a drug of interest that can be repurposed for traumatic brain injury (TBI) treatment. Drug repurposing is a novel approach in drug development that identifies drugs for purposes other than their original indication. This review presents the biochemical properties of edaravone along with its effects on several neurological disorders in the hope that it can be adopted for treating TBI patients.

Corallodiscus flabellata B.L. Burtt Extracts Stimulate Diuretic Activity and Regulate the Renal Expression of Aquaporins

Corallodiscus flabellata B. L. Burtt is a traditional Chinese medicine. Previous studies in our laboratory showed that C. flabellata alleviated symptoms of Alzheimer's disease (AD) in a rat model of AD and increased healthy rats' urine volume. The aims of this study were to explore the diuretic activity of different extracts from C. flabellata and to identify the underlying mechanisms of action. Different doses of a C. flabellata extract (CF-L, CF-M, and CF-H) were administered orally to male KM mice in a single dose. In another procedure, C. flabellata (CF), water extract, and 20%, 30%, and 40% ethanol extracts of C. flabellata (CF-WE, CF-20, CF-30, and CF-40) were administered orally daily for 5 days. The urinary excretion rate, osmolality, and electrolyte levels in urine and serum, renal expression of aquaporins (AQPs), apoptosis-related protein, and MAPK-related protein were analyzed. The results showed that single doses of CF-M and CF-H increased urinary volume significantly, as well as daily administration of CF, CF-WE, CF-20, CF-30, and CF-40. Furthermore, CF-20 and CF-30 increased the concentration of Na⁺ in the urine. Treatment with CF-40 increased the urine osmolality and Na⁺ and Cl⁻ concentrations and decreased the concentration of Na⁺ in the serum. Also, CF, CF-WE, CF-20, CF-30, and CF-40 decreased the renal expression of AQPs, as well as the ratios of Bcl-2/Bax, p-ERK/ERK, p-JNK/JNK, and p-p38/p38. In sum, the medium and high doses of the C. flabellata extract and CF-WE, CF-20, CF-30, and CF-40 were found to have a diuretic activity. They may inhibit the renal expression of AQPs and apoptosis-related proteins by inhibiting the MAPK signaling pathway, thereby achieving diuretic effects.

USP10 protects against cerebral ischemia injury by suppressing inflammation and apoptosis through the inhibition of TAK1 signaling

Cerebral ischemia is a leading cause of death and long-term disability in the world. Multiple signaling pathways play essential roles in the process. Therefore, identifying the unknown important modulators of these pathways may supply promising therapeutic targets for the treatment of cerebral ischemia. Ubiquitin-specific protease 10 (USP10) is a member of the ubiquitin-specific protease family of cysteine proteases with enzymatic activity to cleave ubiquitin from ubiquitin-conjugated protein substrates, and is involved in multiple pathologies. However, the effects of USP10 in cerebral ischemia-reperfusion (I/R) injury remain unclear. Here, we reported that USP10 expression was markedly decreased in wild type (WT) mice after cerebral I/R injury. USP10 knockout (KO) mice showed significantly elevated infarct size and the neurological deficit score after cerebral I/R operation. USP10 deletion also promoted inflammatory response in ischemic penumbra of cortical regions by further accelerating nuclear factor κB (NF-κB) signaling pathway. In addition, apoptosis was markedly induced in USP10-knockout mice after cerebral I/R injury compared to the WT mice. The c-Jun N-terminal kinase-mitogen-activated protein kinase (JNK-MAPK) signaling induced by cerebral I/R injury was further aggravated in USP10-KO mice. Finally, USP10 was found to display protective effects against cerebral I/R injury through direct interaction with transforming growth factor β-activated kinase 1 (TAK1). Thus, USP10 might be a protective factor in cerebral I/R injury. Modulation of USP10/TAK1 might be a promising strategy to prevent this pathological process.

Protective effects of mesenchymal stem cells overexpressing extracellular regulating kinase 1/2 against stroke in rats

OBJECTIVE

Although transplantation of bone marrow-derived mesenchymal stem cells (MSCs) has shown beneficial effects on stroke, lower survival of MSCs limits effects. Extracellular regulating kinase 1/2 signaling (ERK1/2) is crucial for cell survival, differentiation, and proliferation. This study was designed to explore whether MSCs modified by over-expressing ERK1/2 may reinforce beneficial effects on stroke in rats.

METHODS

rat MSCs transfected with ERK1/2 and empty lentivirus to generate MSCs overexpressing ERK1/2 (ERK/MSCs) and MSCs (as a control), respectively. In vitro, ERK/MSCs were plated and exposed to glutamate-induced condition, and viability of ERK/MSCs was measured. Furthermore, neural induction of ERK/MSCs was investigated in vitro. Cerebral ischemic rats were induced by occluding middle cerebral artery, and then were stereotaxically injected into ipsilateral right lateral ventricle with ERK/MSCs or MSCs 3 days after stroke and survived for 7 or 14 days after injection.

RESULTS

ERK/MSCs showed better viability in physiological and glutamate-induced neurotoxic conditions compared to MSCs. After neural induction, more neurons were be differentiated from ERK/MSCs than from MSCs. After transplantation, more numbers of grafted cells and improved functional recovery were observed in ERK/MSCs-treated rats compared with MSCs-treated rats. Compared with MSCs treatment, ERK/MSCs treatment significantly increased proliferation of neural stem cells in the subventricle zone (SVZ) and the MAP2/nestin double-labeled cells adjacent to the SVZ, enhanced the numbers of reactive astrocytes while suppressed microglial activation. Besides, TNF-α level was elevated in ERK/MSCs-treated rats.

CONCLUSION

ERK/MSCs transplantation showed better functional recovery after stroke in rats, likely in part through enhancing survival of MSCs and possibly by modulating the proliferation, neuronal de-differentiation and neuroinflammation.

MicroRNA-410 inhibition of the TIMP2-dependent MAPK pathway confers neuroprotection against oxidative stress-induced apoptosis after ischemic stroke in mice

Ischemic stroke (IS) is an acute cerebral event characterized by a high incidence rate, high disability rate as well as a high mortality. More recently, accumulative literature has provided evidence highlighting the role played by microRNAs (miRs) in the development of neurons. Hence, the aim of the present study was to investigate the neuroprotective role of miR-410 in IS. Microarray-based gene expression profiling of AMI was conducted in order to identify differentially expressed genes (DEGs) and the corresponding miRs regulating these genes. IS models were established to assess neurology on a scoring basis. Superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) activity and malondialdehyde (MDA) were all subsequently assessed. The functional role of miR-410 in IS was determined based on ectopic expression, knockdown and reporter assay experiments in hippocampal neurons. The expressions of microRNA-410, TIMP2, ERK, p38MAPK, JNK were all examined accordingly. The survival rate was assessed by MTT assay, and cell cycle and apoptosis by flow cytometry. After the loss of hippocampal neurons, infarct size as well as oxidative stress injury had been detected, microarray technology revealed that TIMP2 was differentially expressed in IS and that miR-410 regulated TIMP2. Initial observations revealed elevated levels of TIMP2 expression and MDA activity, in addition to evidence obtained indicated that the MAPK pathway had been activated along with decreased SOD, GSH-Px activity and miR-410 expression in IS mice. Ectopic expression of miR-410 was observed to inactivate the MAPK pathway, TIMP2 expression and hippocampal neuron apoptosis, while elevated hippocampal neuron survival rates and cell cycle entry were detected. Furthermore, TIMP2 as a direct target gene of miR-410, was determined to be negatively regulated by miR-410, while the MAPK pathway was found to be inhibited following TIMP2 knockdown. Our results revealed that the overexpression of miR-410 could ameliorate hippocampal neuron loss, reduce infarct size and oxidative stress injury in IS mice. Taken together, the key evidence of the current study elucidated the distinct nature of the inhibitory effect on IS as a result of overexpressed miR-410 whereby the conferral of neuroprotection was observed in oxidative stress-induced apoptosis post IS through the TIMP2-dependent repression of the MAPK pathway in mice.

c-Jun N-Terminal Kinases (JNKs) in Myocardial and Cerebral Ischemia/Reperfusion Injury

In this article, we review the literature regarding the role of c-Jun N-terminal kinases (JNKs) in cerebral and myocardial ischemia/reperfusion injury. Numerous studies demonstrate that JNK-mediated signaling pathways play an essential role in cerebral and myocardial ischemia/reperfusion injury. JNK-associated mechanisms are involved in preconditioning and post-conditioning of the heart and the brain. The literature and our own studies suggest that JNK inhibitors may exert cardioprotective and neuroprotective properties. The effects of modulating the JNK-depending pathways in the brain and the heart are reviewed. Cardioprotective and neuroprotective mechanisms of JNK inhibitors are discussed in detail including synthetic small molecule inhibitors (AS601245, SP600125, IQ-1S, and SR-3306), ion channel inhibitor GsMTx4, JNK-interacting proteins, inhibitors of mixed-lineage kinase (MLK) and MLK-interacting proteins, inhibitors of glutamate receptors, nitric oxide (NO) donors, and anesthetics. The role of JNKs in ischemia/reperfusion injury of the heart in diabetes mellitus is discussed in the context of comorbidities. According to reviewed literature, JNKs represent promising therapeutic targets for protection of the brain and the heart against ischemic stroke and myocardial infarction, respectively. However, different members of the JNK family exert diverse physiological properties which may not allow for systemic administration of non-specific JNK inhibitors for therapeutic purposes. Currently available candidate JNK inhibitors with high therapeutic potential are identified. The further search for selective JNK3 inhibitors remains an important task.

Edaravone promotes activation of resident cardiac stem cells by transplanted mesenchymal stem cells in a rat myocardial infarction model

OBJECTIVE

To explore the effect of edaravone on bone marrow mesenchymal stem cells (BMSCs) transplanted to treat acute myocardial infarction (AMI) and the underlying mechanism.

METHODS

After pretreatment or treatment with edaravone under conditions of deep hypoxia and serum deprivation, the rat BMSCs were evaluated for reactive oxygen species (ROS), Akt pathway, apoptosis, migration, and paracrine function mediating cardiac stem cell (CSC) activation. Edaravone-pretreated BMSCs, control-released edaravone, and BMSCs were respectively transplanted into a rat AMI model. Apoptosis and paracrine functions of the BMSCs, resident CSC activation, and myocardial regeneration and function were measured at various time points.

RESULTS

Compared with the control and edaravone pretreatment, edaravone treatment showed significantly increased apoptosis inhibition, migration, and cytokine secretion of BMSCs under an in vitro deep hypoxia and serum deprivation condition (P < .05), via inhibiting intracellular accumulation of ROS and prolonging the Akt pathway activation. At 24 hours postoperatively, up-regulated expression of cytokines within the transplanted area, and decreased apoptotic BMSCs, were detected in the BMSC + edaravone group, compared with the BMSCs and edaravone pretreatment BMSC groups (n = 10 for each group, P < .05). Four weeks later, the BMSCs + edaravone group showed more CSCs, CSC-derived cardiomyocytes, new vessels, and myocardial density within the ischemic area, and improved ejection fraction, compared with the other groups (n = 10 in each group, P < .05).

CONCLUSIONS

Edaravone can protect the BMSCs against hypoxia and activate their potential to activate CSCs via the Akt pathway. The combined treatment can promote angiogenesis, resident CSC-mediated myocardial regeneration, and cardiac function after AMI, providing a new strategy for cell therapy.

Inhibiting p38 mitogen-activated protein kinase attenuates cerebral ischemic injury in Swedish mutant amyloid precursor protein transgenic mice

Cerebral ischemia was induced using photothrombosis 1 hour after intraperitoneal injection of the p38 mitogen-activated protein kinase (MAPK) inhibitor SB239063 into Swedish mutant amyloid precursor protein (APP/SWE) transgenic and non-transgenic mice. The number of surviving neurons in the penumbra was quantified using Nissl staining, and the activity of p38 MAPKs was measured by western blotting. The number of surviving neurons in the penumbra was significantly reduced in APP/SWE transgenic mice compared with non-transgenic controls 7 days after cerebral ischemia, but the activity of p38 MAPKs was significantly elevated compared with the non-ischemic hemisphere in the APP/SWE transgenic mice. SB239063 prevented these changes. The APP/SWE mutation exacerbated ischemic brain injury, and this could be alleviated by inhibiting p38 MAPK activity.

Neuroprotective effect of gui zhi (ramulus cinnamomi) on ma huang- (herb ephedra-) induced toxicity in rats treated with a ma huang-gui zhi herb pair

Herb Ephedra (Ma Huang in Chinese) and Ramulus Cinnamomi (Gui Zhi in Chinese) are traditional Chinese herbs, often used together to treat asthma, nose and lung congestion, and fever with anhidrosis. Due to the adverse effects of ephedrine, clinical use of Ma Huang is restricted. However, Gui Zhi extract has been reported to decrease spontaneous activity in rats and exert anti-inflammatory and neuroprotective effects. The present study explored the possible inhibitory effect of Gui Zhi on Ma Huang-induced neurotoxicity in rats when the two herbs were used in combination. All Ma Huang and Ma Huang-Gui Zhi herb pair extracts were prepared using methods of traditional Chinese medicine and were normalized based on the ephedrine content. Two-month-old male Sprague-Dawley rats (n = 6 rats/group) were administered Ma Huang or the Ma Huang-Gui Zhi herb pair extracts for 7 days (ephedrine = 48 mg/kg), and locomotor activity was measured. After 7 days, oxidative damage in the prefrontal cortex was measured. Gui Zhi decreased hyperactivity and sensitization produced by repeated Ma Huang administration and attenuated oxidative stress induced by Ma Huang. The results of this study demonstrate the neuroprotective potential of Gui Zhi in Ma Huang-induced hyperactivity and oxidative damage in the prefrontal cortex of rats when used in combination.

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.

Ischemic preconditioning affects long-term cell fate through DNA damage-related molecular signaling and altered proliferation

Despite the potential of ischemic preconditioning for organ protection, long-term effects in terms of molecular processes and cell fates are ill defined. We determined consequences of hepatic ischemic preconditioning in rats, including cell transplantation assays. Ischemic preconditioning induced persistent alterations; for example, after 5 days liver histology was normal, but γ-glutamyl transpeptidase expression was observed, with altered antioxidant enzyme content, lipid peroxidation, and oxidative DNA adducts. Nonetheless, ischemic preconditioning partially protected from toxic liver injury. Similarly, primary hepatocytes from donor livers preconditioned with ischemia exhibited undesirably altered antioxidant enzyme content and lipid peroxidation, but better withstood insults. However, donor hepatocytes from livers preconditioned with ischemia did not engraft better than hepatocytes from control livers. Moreover, proliferation of hepatocytes from donor livers preconditioned with ischemia decreased under liver repopulation conditions. Hepatocytes from donor livers preconditioned with ischemia showed oxidative DNA damage with expression of genes involved in MAPK signaling that impose G1/S and G2/M checkpoint restrictions, including p38 MAPK-regulated or ERK-1/2-regulated cell-cycle genes such as FOS, MAPK8, MYC, various cyclins, CDKN2A, CDKN2B, TP53, and RB1. Thus, although ischemic preconditioning allowed hepatocytes to better withstand secondary insults, accompanying DNA damage and molecular events simultaneously impaired their proliferation capacity over the long term. Mitigation of ischemic preconditioning-induced DNA damage and deleterious molecular perturbations holds promise for advancing clinical applications.

P38 MAPK signaling pathway and hepatic fibrosis

Mitogen-activated protein kinase (MAPK) cascade is one of eukaryotic cell-mediated extracellular signal responses to distinct environmental stresses. P38 MAPK is an important member of the MAPK family and plays an important role in a variety of physiological and pathological processes such as inflammation, cellular stress, apoptosis, cell cycle and growth. This article reviews the role of the P38 MAPK signaling pathway in the pathogenesis of hepatic fibrosis in terms of its structure composition, distribution and subtypes, activation pathways and function.

Perfluorocarbon-facilitated CNS oxygen toxicity in rats: reversal by edaravone

Perfluorocarbon (PFC) has been hypothesized to potentially increase the risk of central nervous system oxygen toxicity (CNS-OT) under hyperbaric oxygen (HBO) conditions. However, little is known about the effects, mechanism and prevention of PFC-facilitated CNS-OT. A rat model of CNS-OT was used to evaluate the effects of intravenously-administered PFC emulsion. The electroencephalogram (EEG) was recorded during treatment with HBO(2) at 6.0 ATA in the presence and absence of PFC. Concentrations of malondialdehyde (MDA), nitric oxide (NO) and hydrogen peroxide (H(2)O(2)) in the brain cortex and hippocampus were quantified. Changes in the activities of superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT) and NO synthase (NOS) in the brain cortex and hippocampus were also determined. Edaravone, a potent antioxidant, was used to prevent PFC-facilitated CNS-OT. The results showed that after PFC administration, the latency to first electrical discharge in EEG was significantly shortened; MDA, H(2)O(2), NO levels and NOS activity increased; and SOD, GPx and CAT activities decreased. Edaravone effectively protected against CNS-OT and the adverse effects of PFC. The results clearly demonstrate that PFC administered before HBO(2) would promote the occurrence of CNS-OT, and edaravone could serve as a promising chemoprophylactic agent to prevent CNS-OT.

Cathepsin B and phospo-JNK in relation to ongoing apoptosis after transient focal cerebral ischemia in the rat

Cathepsin B, one of major lysosomal cathepsins, and JNK, a downstream component of Rho kinase (ROCK), are two families of proteases, which play an important role in ischemic cell apoptosis. However, the interrelationship between Cathepsin B and JNK in apotosis has not been examined. In the present study, rats were decapitated at 0, 2, 6, 24, 48 h of reperfusion after 2 h of middle cerebral artery occlusion (MCAO); TUNEL-positive cells appeared in the ipsilateral preoptic region during reperfusion after 2-h MCAO, and gradually increased to a peak of 24 h after reperfusion; Phospho-JNK (p-JNK) immunoreactivity, occurring after Cathepsin B expression, was gradually increased and peaked altogether with Cathepsin B at 6-h reperfusion; Fasudil (5 mg/kg, intraperitoneally), an inhibitor of ROCK, decreased the level of p-JNK and apoptotic neurons, and had no effect on cathepsin B; Immunofluorescent double labeling showed that the colocalization of cathepsin B with p-JNK appeared in the preoptic region at 2, 6, 24, 48 h of reperfusion. These findings indicate that a signal transduction pathway by ischemia-reperfusion is most likely to exist: lysosomal cathepsin B-Rho/Rho kinase pathway-JNK signaling pathway-mitochondrial-dependent intrinsic pathway.

Edaravone, an ROS scavenger, ameliorates photoreceptor cell death after experimental retinal detachment

PURPOSE

To investigate whether edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one), a free radical scavenger, would be neuroprotective against photoreceptor cell death in a rat model of retinal detachment (RD).

METHODS

RD was induced in adult Brown Norway rats by subretinal injection of sodium hyaluronate. Edaravone (3, 5, or 10 mg/kg) or physiologic saline was administered intraperitoneally once a day until death on day 3 or 5. Oxidative stress in the retina was assessed by 4-hydroxynonenal staining or ELISA for protein carbonyl content. Photoreceptor death was assessed by TUNEL and measurement of the outer nuclear layer thickness. Western blot analysis and caspase activity assays were performed. Inflammatory cytokine secretion and inflammatory cell infiltration were evaluated by ELISA and immunostaining, respectively.

RESULTS

RD resulted in increased generation of ROS. Treatment with 5 mg/kg edaravone significantly reduced the ROS level, along with a decrease in TUNEL-positive cells in the photoreceptor layer. A caspase assay also confirmed decreased activation of caspase-3, -8, and -9 in RD treated with edaravone. The level of the antiapoptotic Bcl-2 was increased in detached retinas after edaravone treatment, whereas the levels of the stress-activated p-ERK1/2 were decreased. In addition, edaravone treatment resulted in a significant decrease in the levels of TNF-α, MCP-1, and macrophage infiltration.

CONCLUSIONS

Oxidative stress plays an important role in photoreceptor cell death after RD. Edaravone treatment may aid in preventing photoreceptor cell death after RD by suppressing ROS-induced photoreceptor damage.

The ubiquitin ligase MuRF1 protects against cardiac ischemia/reperfusion injury by its proteasome-dependent degradation of phospho-c-Jun

Despite improvements in interventions of acute coronary syndromes, primary reperfusion therapies restoring blood flow to ischemic myocardium leads to the activation of signaling cascades that induce cardiomyocyte cell death. These signaling cascades, including the mitogen-activated protein kinase signaling pathways, activate cardiomyocyte death in response to both ischemia and reperfusion. We have previously identified muscle ring finger-1 (MuRF1) as a cardiac-specific protein that regulates cardiomyocyte mass through its ubiquitin ligase activity, acting to degrade sarcomeric proteins and inhibit transcription factors involved in cardiac hypertrophy signaling. To determine MuRF1's role in cardiac ischemia/reperfusion (I/R) injury, cardiomyocytes in culture and intact hearts were challenged with I/R injury in the presence and absence of MuRF1. We found that MuRF1 is cardioprotective, in part, by its ability to prevent cell death by inhibiting Jun N-terminal kinase (JNK) signaling. MuRF1 specifically targets JNK's proximal downstream target, activated phospho-c-Jun, for degradation by the proteasome, effectively inhibiting downstream signaling and the induction of cell death. MuRF1's inhibitory affects on JNK signaling through its ubiquitin proteasome-dependent degradation of activated c-Jun is the first description of a cardiac ubiquitin ligase inhibiting mitogen-activated protein kinase signaling. MuRF1's cardioprotection in I/R injury is attenuated in the presence of pharmacologic JNK inhibition in vivo, suggesting a prominent role of MuRF1's regulation of c-Jun in the intact heart.

Edaravone protects against apoptotic neuronal cell death and improves cerebral function after traumatic brain injury in rats

Edaravone is a novel free radical scavenger used clinically in patients with acute cerebral infarction; however, it has not been assessed in traumatic brain injury (TBI). We investigated the effects of edaravone on cerebral function and morphology following TBI. Rats received TBI with a pneumatic controlled injury device. Edaravone (3 mg/kg) or physiological saline was administered intravenously following TBI. Numbers of 8-OHdG-, 4-HNE-, and ssDNA-positive cells around the damaged area after TBI were significantly decreased in the edaravone group compared with the saline group (P < 0.01). There was a significant increase in neuronal cell number and improvement in cerebral dysfunction after TBI in the edaravone group compared with the saline group (P < 0.01). Edaravone administration following TBI inhibited free radical-induced neuronal degeneration and apoptotic cell death around the damaged area. In summary, edaravone treatment improved cerebral dysfunction following TBI, suggesting its potential as an effective clinical therapy.

The novel free radical scavenger, edaravone, increases neural stem cell number around the area of damage following rat traumatic brain injury

Edaravone is a novel free radical scavenger that is clinically employed in patients with acute cerebral infarction, but has not previously been used to treat traumatic brain injury (TBI). In this study, we investigated the effect of edaravone administration on rat TBI. In particular, we used immunohistochemistry to monitor neural stem cell (NSC) proliferation around the area damaged by TBI. Two separate groups of rats were administered saline or edaravone (3 mg/kg) after TBI and then killed chronologically. We also used ex vivo techniques to isolate NSCs from the damaged region and observed nestin-positive cells at 1, 3, and 7 days following TBI in both saline- and edaravone-treated groups. At 3 days following TBI in both groups, there were many large cells that morphologically resembled astrocytes. At 1 and 7 days following TBI in the saline group, there were a few small nestin-positive cells. However, in the edaravone group, there were many large nestin-positive cells at 7 days following TBI. At 3 and 7 days following TBI, the number of nestin-positive cells in the edaravone group increased significantly compared with the saline group. There were many single-stranded DNA-, 8-hydroxy-2'-deoxyguanosine-, and 4-hydroxy-2-nonenal-positive cells in the saline group following TBI, but only a few such cells in the edaravone group following TBI. Furthermore, almost all ssDNA-positive cells in the saline group co-localized with Hu, nestin, and glial fibrillary acidic protein (GFAP) staining, but not in the edaravone group. In the ex vivo study, spheres could only be isolated from injured brain tissue in the saline group at 3 days following TBI. However, in the edaravone group, spheres could be isolated from injured brain tissue at both 3 and 7 days following TBI. The number of spheres isolated from injured brain tissue in the edaravone group showed a significant increase compared with the saline group. The spheres isolated from both saline and edaravone groups were immunopositive for nestin, but not Tuj1 or vimentin. Moreover, the spheres differentiated into Tuj1-, GFAP-, and O4-positive cells after 4 days in culture without bFGF. This result indicated that the spheres were neurospheres composed of NSCs that could differentiate into neurons and glia. Edaravone administration inhibited production of free radicals known to induce neuronal degeneration and cell death after brain injury, and protected nestin-positive cells, including NSCs, with the potential to differentiate into neurons and glia around the area damaged by TBI.

Protecting mechanism of puerarin on the brain neurocyte of rat in acute local ischemia brain injury and local cerebral ischemia-reperfusion injury

The present study was designed to investigate the possible properties of the injured brain neurocytes, the expression of heat shock protein70 (HSP70) and Fas protein after acute local ischemia brain injury and local cerebral ischemia-reperfusion injury in rats and to investigate the protecting mechanism of puerarin on the brain neurocytes of rats in acute local ischemia brain injury and local cerebral ischemia-reperfusion injury. A rat model of acute local cerebral ischemia was made by ligatting the middle cerebral artery. The rat model of local cerebral ischemia and reperfusion injury was made by ligatting the middle cerebral artery for 30 min then opened for 30 min. Rats of puerarin treating group were injected with puerarin in dose of 30 mg/kg(-1) by intraperitoneal injection 30 min before ischemia. HSP70 and Fas protein expressions in brain tissue were detected by SP method of histochemistry. In addition, dead brain neurocytes were counted and their morphology was observed. The results indicated that puerarin can limit the tissue injury caused by local cerebral ischemia injury through improving expression of HSP70, and limit the tissue injury caused by local cerebral ischemia-reperfusion through decreasing the Fas expression and improving expression of HSP70. On the basis of these results, it may be concluded that puerarin can protect the brain neurocytes of rats in acute local ischemia brain injury and local cerebral ischemia-reperfusion injury, which may be different according to the different injury mechanism.

Edaravone (MCI-186), a free radical scavenger, attenuates retinal ischemia/reperfusion injury in rats

AIM

To investigate the effect of edaravone (MCI-186), a free radical scavenger, against ischemia/reperfusion (I/R) injury in the rat retina.

METHODS

Retinal ischemia was induced in male Sprague-Dawley rats by elevating intraocular pressure to 110 mmHg for 60 min. The rats were intraperitoneally injected with edaravone at a dose of 3 mg/kg at 30 min before ischemia, and then treated with edaravone (3 mg/kg, ip) twice daily for 1 or 5 d after I/R. The levels of malondialdehyde (MDA) and superoxide dismutase (SOD) in the retinal tissues were determined on d 1 after I/R injury. The apoptosis of retinal neurons was detected on d 1 after I/R injury by terminal deoxynucleotidyl transferase-mediated digoxigenin-dUTP nick-end labeling staining. The electroretinogram (ERG) was recorded on d 5 after reperfusion.

RESULTS

Edaravone lowered MDA levels, raised SOD activity, and attenuated I/R-induced apoptosis of retinal neurons within the inner nuclear, ganglion cell, and outer nuclear layers of the rat retina. Moreover, edaravone suppressed I/R-induced reduction in a- and b-wave amplitudes of ERG.

CONCLUSION

Edaravone can protect the retina from I/R injury in rats through reducing oxidative stress and inhibiting apoptosis of retinal neurons, which suggests that edaravone might be a potential choice for the treatment of I/R-induced eye disorders.

Defects in tongue papillae and taste sensation indicate a problem with neurotrophic support in various neurological diseases

Neurotrophic support of developing neurons by neurotrophins is of critical importance in the development of fungiform papillae and taste buds. A number of neurological disorders show a decrease or increase in fungiform papillae or taste sensation. These can be grouped into disorders with reduced papillae (Machado-Joseph disease, Stüve-Wiedemann syndrome, familial dysautonomia, dystonia musculorum, and Behçet's disease) and those with taste defects only (Alzheimer's disease, Huntington's disease, hereditary sensory and autonomic neuropathy type IV, and diabetes mellitus). In addition, Parkinson's disease results in increased taste sensation. Here, we hypothesize that the main problem in these disorders is either not enough or too much neurotrophic support. Proneurotrophic drugs such as some antidepressants and aldose reductase inhibitors may prove useful in the treatment of these sensory and central nervous system disorders. Similarly, antineurotrophic drugs may also be useful in Parkinson's disease. Here we show that the protein involved in familial dysautonomia, IKAP, localizes to keratin filaments in HeLa cells, suggesting a role for the keratin cytoskeleton in neurotrophic support.

Does edaravone (MCI- 186) act as an antioxidant and a neuroprotector in experimental traumatic brain injury?

Edaravone (MCI-186) is a novel synthetic free radical scavenger intended to have neuroprotective effect against ischemic insult. It is currently used on patients with cerebral infarction. Here, we note beneficial pharmaceutical effects of edaravone in rat experimental traumatic brain injury. Under specific experimental conditions, edaravone minimized traumatic brain injury by functioning as a synthetic antioxidant. Clinical trials testing the efficacy of edaravone are warranted.

Molecular targets in cerebral ischemia for developing novel therapeutics

Cerebral ischemia (stroke) triggers a complex series of biochemical and molecular mechanisms that impairs the neurologic functions through breakdown of cellular integrity mediated by excitotoxic glutamatergic signalling, ionic imbalance, free-radical reactions, etc. These intricate processes lead to activation of signalling mechanisms involving calcium/calmodulin-dependent kinases (CaMKs) and mitogen-activated protein kinases (MAPKs) such as extracellular signal-regulated kinase (ERK), p38, and c-Jun N-terminal kinase (JNK). The distribution of these transducers bring them in contact with appropriate molecular targets leading to altered gene expression, e.g. ERK and JNK mediated early gene induction, responsible for activation of cell survival/damaging mechanisms. Moreover, inflammatory reactions initiated at the neurovascular interface and alterations in the dynamic communication between the endothelial cells, astrocytes and neurons are thought to substantially contribute to the pathogenesis of the disease. The damaging mechanisms may proceed through rapid nonspecific cell lysis (necrosis) or by active form of cell demise (apoptosis or necroptosis), depending upon the severity and duration of the ischemic insult. A systematic understanding of these molecular mechanisms with prospect of modulating the chain of events leading to cellular survival/damage may help to generate the potential strategies for neuroprotection. This review briefly covers the current status on the molecular mechanisms of stroke pathophysiology with an endeavour to identify potential molecular targets such as targeting postsynaptic density-95 (PSD-95)/N-methyl-d-aspartate (NMDA) receptor interaction, certain key proteins involved in oxidative stress, CaMKs and MAPKs (ERK, p38 and JNK) signalling, inflammation (cytokines, adhesion molecules, etc.) and cell death pathways (caspases, Bcl-2 family proteins, poly (ADP-ribose) polymerase-1 (PARP-1), apoptosis-inducing factor (AIF), inhibitors of apoptosis proteins (IAPs), heat shock protein 70 (HSP70), receptor interacting protein (RIP), etc., besides targeting directly the genes itself. However, selecting promising targets from various signalling cascades, for drug discovery and development is very challenging, nevertheless such novel approaches may lead to the emergence of new avenues for therapeutic intervention in cerebral ischemia.

Effects of Edaravone in Heart of Aged Rats after Cerebral Ischemia-Reperfusion Injury

Edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one) has potent effects in the brain as a free radical scavenger in ischemia-reperfusion (IR) injuries. However, whether this free radical scavenger can prevent myocardial injury after cerebral IR is not clear. The aim of the present study was to investigate the effect of edaravone against oxidative damage in brain-to-heart signaling triggered by IR injury and its possible mechanism. In this study, the expression of glutathione peroxidase (GSHPx) and protein carbonyl content was examined to evaluate oxidative stress. The activation of mitogen-activated protein kinases (MAPKs) was also examined. Terminal deoxynucleotidyl transferase nick-end labeling (TUNEL) analysis was performed to estimate cardiomyocytes cell death. After edaravone treatment there was a mild increase in activities of GSHPx in cardiomyocytes; however, there was a decrease in protein carbonyl content. p38 MAPK activity was inhibited by edaravone treatment in comparison with the vehicle group in myocardium. These results were further complemented by a significant reduction of TUNEL-positive cells in the heart sections. Our results demonstrate that edaravone provides ameliorative effects in the myocardium after cerebral IR injury by differentially modulating MAPK's activity, thus reducing the oxidative stress state.

Neuronal angiotensin II type 1 receptor upregulation in heart failure: activation of activator protein 1 and Jun N-terminal kinase

Chronic heart failure (CHF) is a leading cause of mortality in developed countries. Angiotensin II (Ang II) plays an important role in the development and progression of CHF. Many of the important functions of Ang II are mediated by the Ang II type 1 receptor (AT(1)R), including the increase in sympathetic nerve activity in CHF. However, the central regulation of the AT(1)R in the setting of CHF is not well understood. This study investigated the AT(1)R in the rostral ventrolateral medulla (RVLM) of rabbits with CHF, its downstream pathway, and its gene regulation by the transcription factor activator protein 1 (AP-1). Studies were performed in 5 groups of rabbits: sham (n=5), pacing-induced (3 to 4 weeks) CHF (n=5), CHF with intracerebroventricular (ICV) losartan treatment (n=5), normal with ICV Ang II treatment (n=5), and normal with ICV Ang II plus losartan treatment (n=5). AT(1)R mRNA and protein expressions, plasma Ang II, and AP-1-DNA binding activity were significantly higher in RVLM of CHF compared with Sham rabbits (240.4+/-30.2%, P<0.01; 206.6+/-25.8%, P<0.01; 280+/-36.5%, P<0.05; 207+/-16.4%, P<0.01, respectively). Analysis of the stress-activated protein kinase/Jun N-terminal kinase (SAPK/JNK) pathway showed that phosphorylated c-Jun proteins, phosphorylated JNK proteins, and JNK activity increased significantly in RVLM of CHF compared with sham (262.9+/-48.1%, 213.8+/-27.7%, 148.2+/-10.1% of control, respectively). Importantly, ICV losartan in CHF rabbits attenuated these increases. ICV Ang II in normal rabbits simulated the molecular changes seen in CHF. This effect was blocked by concomitant ICV losartan. In addition, Ang II-induced AT(1)R expression was blocked by losartan and a JNK inhibitor, but not by extracellular signal-regulated kinase or p38 MAP kinase inhibitors in a neuronal cell culture. These data suggest that central Ang II activates the AT(1)R, SAPK/JNK pathway. AP-1 may further regulate gene expression in RVLM in the CHF state.

Effects of edaravone on N-methyl-D-aspartate (NMDA)-mediated cytochrome c release and apoptosis in neonatal rat cerebrocortical slices

N-Methyl-D-aspartate-mediated neurotoxicity is known to involve nitric oxide production and to be augmented in an environment of reactive oxygen species. We used TUNEL staining and homogenous cytosolic immunoreactivity of cytochrome c in an acute brain slice preparation to investigate the influence of edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one), a free radical scavenger, on N-methyl-D-aspartate-induced apoptosis. Cerebrocortical slices were obtained from parietal lobes of 7-day-old Sprague-Dawley rats, superfused with well-oxygenated artificial cerebrospinal fluid, and metabolically recovered. Subsequent 30-min exposures to 10 microM N-methyl-D-aspartate in treated and untreated slices were followed by 4 h of recovery superfusion with oxygenated artificial cerebrospinal fluid. Outcomes were compared for three groups of slices: "the N-methyl-D-aspartate-only group"; "the edaravone treatment group", which had 20 microM edaravone present throughout and subsequent to N-methyl-D-aspartate exposure; the "control group", in which slices were superfused only with oxygenated artificial cerebrospinal fluid. At the conclusion of recovery (t = 4 h), the percentage of TUNEL-positive cells in the edaravone treatment group (7.0+/-3.3%) was significantly reduced from the percentage for the N-methyl-D-aspartate-only group (21.9+/-4.1%), and insignificantly greater than the percentage for the control group (3.4+/-2.1%). Percentages of cytochrome c positive cells at t = 1 h were significantly increased (p < 0.01) in the N-methyl-d-aspartate-only group (30.6+/-1.9%) compared to percentages for both the control group (11.4+/-2.6%) and the edaravone treatment group (15.2+/-2.1%). Edaravone's reduction in TUNEL staining and cytochrome c release provides evidence of reactive oxygen species mechanisms and antioxidant benefits in cytochrome c-mediated apoptosis during N-methyl-D-aspartate excitotoxicity.