Edaravone, a free radical scavenger, mitigates both gray and white matter damages after global cerebral ischemia in rats

Edaravone Improves Motor Dysfunction Following Brachial Plexus Avulsion Injury in Rats

Brachial plexus root avulsion (BPRA) is often caused by road collisions, leading to total loss of motor function in the upper limb. At present, effective treatment options remain limited. Edaravone (EDA), a substance that eliminates free radicals, exhibits numerous biological properties, including neuroprotective, antioxidant and anti-inflammatory effects. However, the specific role and molecular mechanisms of EDA in the treatment of BPRA remain to be fully elucidated. The present study used a rat model of BPRA, following avulsion of the fifth, sixth and seventh cervical (C5, C6 and C7) anterior roots. Notably, C6 was replanted following a subcutaneous injection of either saline or 30 mg/kg/day EDA for seven continuous days. Subsequently, behavioral, histochemical, Western blot and reverse transcription-quantitative PCR (RT-PCR) analyses were conducted. Results of the present study revealed that treatment with EDA improves motor dysfunction, indicated by the increased Grooming test score, usage of the affected limb, and Irvine, Beatties and Bresnahan (IBB) score, following BPRA. In addition, EDA reduced the death of motoneurons (MNs), indicated by the increased number of Nissl-positive neuron, at the site of the affected limb, inhibited neuroinflammation and cellular pyroptosis, indicated by the decreased expression levels of IL-1β, IL-6, TNF-α, IL-18, p-p65, NLRP3, GSDMD and Caspase-1, improved the morphology of the abnormal myocutaneous nerve fibers, promoted axon remyelination, indicated by increased mRNA expression levels of remyelination-associated genes, including egr2, GAP-43, hmgcr, L1CAM, mpz, pmp22 and prx and demyelination-associated genes, including ngfr, notch1, pou3f1 and sox2, and alleviated muscle atrophy, indicated by the increased weight and volume of biceps brachii muscle, and the decreased number of fibroblasts and increased diameters in the fibers. Collectively, results of the present study suggested that EDA may support axonal remyelination and inhibit pyroptosis-associated neuroinflammation, enhancing MN survival and facilitating functional motor recovery. Thus, the present study may provide a novel theoretical basis for the use of EDA in the treatment of BPRA.

Blood-Brain Barrier Rescue by Roflumilast After Transient Global Cerebral Ischemia in Rats

Phosphodiesterase 4 inhibitors (PDE4-I), which selectively increase cyclic adenosine monophosphate (cAMP) levels, have shown neuroprotective effects after several neurological injuries inducing blood-brain barrier (BBB) damage including local/focal cerebral ischemia. The present investigated whether roflumilast confers BBB neuroprotection in the hippocampus after transient global cerebral ischemia (TGCI) in rats. TGCI resulted in whole BBB disruption as measured by the increase of Evans blue (EB) and IgG extravasation, neurodegeneration, and downregulation of claudin-5 and endothelial nitric oxide synthase (eNOS) levels in the CA1 hippocampal subfield of ischemic rats. Roflumilast attenuated BBB disruption and restored the levels of eNOS in the CA1 hippocampal area. Moreover, roflumilast increased the levels of B2 cell lymphoma (BcL-2) and neuron-glial antigen-2 (NG2) in the CA1 subfield after global ischemia in rats. The protective effects of roflumilast against TGCI-induced BBB breakdown might involve preservation of BBB integrity, vascularization and angiogenesis, and myelin repair.

Effects of Ceftriaxone on Oxidative Stress and Inflammation in a Rat Model of Chronic Cerebral Hypoperfusion

Ceftriaxone (CTX) exerts a neuroprotective effect by decreasing glutamate excitotoxicity. We further studied the underlying mechanisms and effects of CTX early post-treatment on behavior in a cerebral hypoperfusion rats. The rats’ common carotid arteries (2VO) were permanently ligated. CTX was treated after ischemia. Biochemical studies were performed to assess antioxidative stress and inflammation. Behavioral and histological studies were then tested on the ninth week after vessel ligation. The 2VO rats showed learning and memory deficits as well as working memory impairments without any motor weakness. The treatment with CTX was found to attenuate white matter damage, MDA production, and interleukin 1 beta and tumor necrosis factor alpha production, mainly in the hippocampal area. Moreover, CTX treatment could increase the expression of glia and the glial glutamate transporters, and the neuronal glutamate transporter. Taken together, our data indicate the neuroprotective mechanisms of CTX involving the upregulation of glutamate transporters’ expression. This increased expression contributes to a reduction in glutamate excitotoxicity and oxidative stress as well as pro-inflammatory cytokine production, thus resulting in the protection of neurons and tissue from further damage. The present study highlights the mechanism of the effect of CTX treatment and of the underlying ischemia-induced neuronal damage.

High replication stress and limited Rad51-mediated DNA repair capacity, but not oxidative stress, underlie oligodendrocyte precursor cell radiosensitivity

Cranial irradiation is part of the standard of care for treating pediatric brain tumors. However, ionizing radiation can trigger serious long-term neurologic sequelae, including oligodendrocyte and brain white matter loss enabling neurocognitive decline in children surviving brain cancer. Oxidative stress-mediated oligodendrocyte precursor cell (OPC) radiosensitivity has been proposed as a possible explanation for this. Here, however, we demonstrate that antioxidants fail to improve OPC viability after irradiation, despite suppressing oxidative stress, suggesting an alternative etiology for OPC radiosensitivity. Using systematic approaches, we find that OPCs have higher irradiation-induced and endogenous γH2AX foci compared to neural stem cells, neurons, astrocytes and mature oligodendrocytes, and these correlate with replication-associated DNA double strand breakage. Furthermore, OPCs are reliant upon ATR kinase and Mre11 nuclease-dependent processes for viability, are more sensitive to drugs increasing replication fork collapse, and display synthetic lethality with PARP inhibitors after irradiation. This suggests an insufficiency for homology-mediated DNA repair in OPCs-a model that is supported by evidence of normal RPA but reduced RAD51 filament formation at resected lesions in irradiated OPCs. We therefore propose a DNA repair-centric mechanism of OPC radiosensitivity, involving chronically-elevated replication stress combined with 'bottlenecks' in RAD51-dependent DNA repair that together reduce radiation resilience.

Potential therapeutic agents for ischemic white matter damage

Ischemic white matter damage (WMD) is increasingly being considered as one of the major causes of neurological disorders in older adults and preterm infants. The functional consequences of WMD triggers a progressive cognitive decline and dementia particularly in patients with ischemic cerebrovascular diseases. Despite the major stride made in the pathogenesis mechanisms of ischemic WMD in the last century, effective medications are still not available. So, there is an urgent need to explore a promising approach to slow the progression or modify its pathological course. In this review, we discussed the animal models, the pathological mechanisms and the potential therapeutic agents for ischemic WMD. The development in the studies of anti-oxidants, free radical scavengers, anti-inflammatory or anti-apoptotic agents and neurotrophic factors in ischemic WMD were summarized. The agents which either alleviate oligodendrocyte damage or promote its proliferation or differentiation may have potential value for the treatment of ischemic WMD. Moreover, drugs with multifaceted protective activities or a wide therapeutic window may be optimal for clinical translation.

Effects of total saponins from Trillium tschonoskii rhizome on grey and white matter injury evaluated by quantitative multiparametric MRI in a rat model of ischemic stroke

ETHNOPHARMACOLOGICAL RELEVANCE

Trillium tschonoskii rhizome (TTR), a medicinal herb, has been traditionally used to treat traumatic brain injury and headache in China. Although the potential neuroprotective efficacy of TTR has gained increasing interest, the pharmacological mechanism remains unclear. Steroid saponins are the main bioactive components of the herb.

AIM OF THE STUDY

To investigate the protective and repair-promoting effects of the total saponins from TTR (TSTT) on grey and white matter damages in a rat model of middle cerebral artery occlusion (MCAO) using magnetic resonance imaging (MRI) assay.

MATERIALS AND METHODS

Ischemic stroke was induced by MCAO. TSTT and Ginaton (positive control) were administered orally to rats 6h after stroke and daily thereafter. After 15 days of treatment, the survival rate of each group was calculated. We then conducted neurological deficit scores and beam walking test to access the neurological function after ischemic stroke. Subsequently, T2-weighted imaging (T2WI) and T2 relaxometry mapping were performed to measure infarct volume and grey and white matter integrity, respectively. Moreover, diffusion tensor imaging (DTI) was carried out to evaluate the grey and white matter microstructural damage. Additionally, arterial spin labelling (ASL) - cerebral blood flow (CBF) and magnetic resonance angiography (MRA) images provided dynamic information about vascular hemodynamic dysfunction after ischemic stroke. Finally, haematoxylin and eosin (HE) staining was carried out to evaluate the stroke-induced pathological changes in the brain.

RESULTS

The survival rate and neurological behavioural outcomes (Bederson scores and beam walking tests) were markedly ameliorated by TSTT (65mg/kg) treatment within 15 days after ischemic stroke. Moreover, T2WI and T2 relaxometry mapping showed that TSTT (65mg/kg) significantly reduced infarct volume and attenuated grey and white matter injury, respectively, which was confirmed by histopathological evaluation of brain tissue. The results obtained from DTI showed that TSTT (65mg/kg) not only significantly alleviated axonal damage and demyelination, but also promoted axonal remodelling and re-myelination. In addition, TSTT treatment also enhanced vascular signal density and increased CBF in rats after MCAO.

CONCLUSION

Our results suggested the potential protective and repair-promoting effects of TSTT on grey and white matter from damage induced by ischemia. This study provides a modern pharmacological basis for the application of TSTT in managing ischemic stroke.

Persistent isoflurane-induced hypotension causes hippocampal neuronal damage in a rat model of chronic cerebral hypoperfusion

BACKGROUND

Postoperative cognitive dysfunction (POCD) is likely to occur in elderly people, who often suffer from cerebral hypoperfusion and white matter lesions even in the absence of cerebral infarctions.

METHODS

Thirty-two adult male rats were randomly assigned to one of four groups: the cerebral normoperfusion + normotension group (n = 8), cerebral normoperfusion + hypotension group (n = 8), chronic cerebral hypoperfusion (CCH) + normotension group (n = 8), and CCH + hypotension group (n = 8). A rat model of CCH was developed via the permanent ligation of the bilateral common carotid arteries, but ligation was avoided in the cerebral normoperfusion groups. Two weeks later, the rats were intubated and mechanically ventilated under isoflurane anesthesia, and their mean arterial blood pressure was maintained over 80 mmHg (normotension) or below 60 mmHg (hypotension) for 2 h. After preparing brain slices, histological cresyl violet staining, ionized calcium binding adaptor molecule 1, a marker of microglial activation, or β amyloid precursor protein, a marker of axonal damage, were performed.

RESULTS AND CONCLUSION

CCH per se caused microglial activation and axonal damage, which was not accentuated by hypotension. CCH alone did not cause neuronal damage, but CCH combined with hypotension caused significant neuronal damage in the hippocampal CA1 region. These results suggest that persistent hypotension during general anesthesia might cause neuronal damage in patients with CCH, such as elderly people, and contribute to prevention against POCD.

Single administration of soluble epoxide hydrolase inhibitor suppresses neuroinflammation and improves neuronal damage after cardiac arrest in mice

Cardiac arrest (CA) causes ischemia-reperfusion injury in the whole body among victims. Especially in the brain, inflammation and neuronal cell death can lead to irreversible dysfunction. Our goal was to determine whether a single administration of soluble epoxide hydrolase inhibitor (AS2586144-CL) has a neuroprotective effect and decreases the inflammatory response after CA and cardiopulmonary resuscitation (CPR). Global cerebral ischemia was induced in male C57BL/6 mice with 8min of CA. Thirty minutes after recovery of spontaneous circulation, the mice were randomly assigned to three groups and administered AS2586144-CL: 1mg/kg (n=25), 10mg/kg (n=25), or 0mg/kg (vehicle, n=25). At 6 and 7 days after CA/CPR, behavioral tests were conducted and brains were removed for histological evaluation. Analysis of histological damage 7 days after CA/CPR revealed that 10mg/kg of AS2586144-CL protected neurons, and suppressed cytokine production and microglial migration into the hippocampus. Two hours after CA/CPR, 10mg/kg of AS2586144-CL suppressed serum tumor necrosis factor-α and hippocampal nuclear factor κB expression. Our data show that 10mg/kg of AS2586144-CL administered following CA/CPR suppresses inflammation and decreases neuronal damage.

Oxidative DNA Damage Mediated by Intranuclear MMP Activity Is Associated with Neuronal Apoptosis in Ischemic Stroke

Evidence of the pathological roles of matrix metalloproteinases (MMPs) in various neurological disorders has made them attractive therapeutic targets. MMPs disrupt the blood-brain barrier and cause neuronal death and neuroinflammation in acute cerebral ischemia and are critical for angiogenesis during recovery. However, some challenges have to be overcome before MMPs can be further validated as drug targets in stroke injury. Identifying in vivo substrates of MMPs should greatly improve our understanding of the mechanisms of ischemic injury and is critical for providing more precise drug targets. Recent works have uncovered nontraditional roles for MMPs in the cytosol and nucleus. These have shed light on intracellular targets and biological actions of MMPs, adding additional layers of complexity for therapeutic MMP inhibition. In this review, we discussed the recent advances made in understanding nuclear location of MMPs, their regulation of intranuclear sorting, and their intranuclear proteolytic activity and substrates. In particular, we highlighted the roles of intranuclear MMPs in oxidative DNA damage, neuronal apoptosis, and neuroinflammation at an early stage of stroke insult. These novel data point to new putative MMP-mediated intranuclear actions in stroke-induced pathological processes and may lead to novel approaches to treatment of stroke and other neurological diseases.

The axon-glia unit in white matter stroke: mechanisms of damage and recovery

Approximately one quarter of all strokes in humans occur in white matter, and the progressive nature of white matter lesions often results in severe physical and mental disability. Unlike cortical grey matter stroke, the pathology of white matter stroke revolves around disrupted connectivity and injured axons and glial cells, rather than neuronal cell bodies. Consequently, the mechanisms behind ischemic damage to white matter elements, the regenerative responses of glial cells and their signaling pathways, all differ significantly from those in grey matter. Development of effective therapies for white matter stroke would require an enhanced understanding of the complex cellular and molecular interactions within the white matter, leading to the identification of new therapeutic targets. This review will address the unique properties of the axon-glia unit during white matter stroke, describe the challenging process of promoting effective white matter repair, and discuss recently-identified signaling pathways which may hold potential targets for repair in this disease. This article is part of a Special Issue entitled SI: Cell Interactions In Stroke.

Pre- and posttreatment with edaravone protects CA1 hippocampus and enhances neurogenesis in the subgranular zone of dentate gyrus after transient global cerebral ischemia in rats

Edaravone is clinically used for treatment of patients with acute cerebral infarction. However, the effect of double application of edaravone on neurogenesis in the hippocampus following ischemia remains unknown. In the present study, we explored whether pre- and posttreatment of edaravone had any effect on neural stem/progenitor cells (NSPCs) in the subgranular zone of hippocampus in a rat model of transient global cerebral ischemia and elucidated the potential mechanism of its effects. Male Sprague-Dawley rats were divided into three groups: sham-operated (n = 15), control (n = 15), and edaravone-treated (n = 15) groups. Newly generated cells were labeled by 5-bromo-2-deoxyuridine. Immunohistochemistry was used to detect neurogenesis. Terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling was used to detect cell apoptosis. Reactive oxygen species (ROS) were detected by 2,7-dichlorofluorescien diacetate assay in NSPCs in vitro. Hypoxia-inducible factor-1α (HIF-1α) and cleaved caspase-3 proteins were quantified by western blot analysis. Treatment with edaravone significantly increased the number of NSPCs and newly generated neurons in the subgranular zone (p < .05). Treatment with edaravone also decreased apoptosis of NSPCs (p < .01). Furthermore, treatment with edaravone significantly decreased ROS generation and inhibited HIF-1α and cleaved caspase-3 protein expressions. These findings indicate that pre- and posttreatment with edaravone enhances neurogenesis by protecting NSPCs from apoptosis in the hippocampus, which is probably mediated by decreasing ROS generation and inhibiting protein expressions of HIF-1α and cleaved caspase-3 after cerebral ischemia.

Pinocembrin alleviates memory impairment in transient global cerebral ischemic rats

The aim of the present study was to investigate the effect of pinocembrin on cognitive ability impairment in a rat model of transient global cerebral ischemia (TGCI). The TGCI model was established by inducing global cerebral ischemia for 20 min, followed by reperfusion for two weeks. The rats were divided into five experimental groups, including the sham group that were not subjected to ischemia, and four ischemic groups where the rats were exposed to TGCI. The sham and control TGCI groups were administered a vehicle intravenously immediately after reperfusion, while the other three groups were intravenously treated with 1, 5 and 10 mg/kg pinocembrin, respectively. In the present study, neurological scores were analyzed at 0 and 24 h after reperfusion, and the effect of pinocembrin on cognitive ability impairment in the TGCI rat model was investigated using a Morris water maze test. Neuronal loss was observed under an optical microscope with the assistance of Nissl staining. In addition, glial fibrillary acidic protein (GFAP)-positive cells were observed under an optical microscope by an immunohistochemistry assay. Pinocembrin treatment was found to alleviate the cognitive impairments, decrease the neurological scores, diminish neuronal loss in the hippocampus and reduce the number of GFAP-positive cells in the hippocampal CA1 region of the TGCI rats. Therefore, pinocembrin alleviated memory impairment in the TGCI rats.

Oligodendrocyte pathophysiology and treatment strategies in cerebral ischemia

Oligodendrocytes (OLs), the myelin-forming cells of the central nervous system, form a functional unit with axons and play a crucial role in axonal integrity. An episode of hypoxia-ischemia causes rapid and severe damage to these particularly vulnerable cells via multiple pathways such as overactivation of glutamate and ATP receptors, oxidative stress, and disruption of mitochondrial function. The cardinal effect of OL pathology is demyelination and dysmyelination, and this has profound effects on axonal function, transport, structure, metabolism, and survival. The OL is a primary target of ischemia in adult-onset stroke and especially in periventricular leukomalacia and should be considered as a primary therapeutic target in these conditions. More emphasis is needed on therapeutic strategies that target OLs, myelin, and their receptors, as these have the potential to significantly attenuate white matter injury and to establish functional recovery of white matter after stroke. In this review, we will summarize recent progress on the role of OLs in white matter ischemic injury and the current and emerging principles that form the basis for protective strategies against OL death.

Effect of tramadol on behavioral alterations and lipid peroxidation after transient forebrain ischemia in rats

N-methyl-D-aspartate (NMDA) antagonists and γ-aminobutyric acid (GABA) agonists are proven protective in various animal models of ischemic brain damage. Tramadol, a centrally acting opioid analgesic reportedly possesses NMDA antagonistic and GABA agonistic properties, with additional ion channel blocking activity. The aim of the present study was to evaluate the possible neuroprotective effect of tramadol hydrochloride in a rat model of transient forebrain ischemia. Male Wistar rats were pretreated with tramadol hydrochloride at doses of 10 and 20 mg/kg b.w. intraperitoneally for 4 days and were subjected to 30 min occlusion of bilateral common carotid arteries followed by reperfusion for 24 h. Impairment in sensorimotor functions was evaluated by beam walking task, spontaneous locomotor activity and hanging wire test. Animals were sacrificed and the brain homogenates were used for estimating the levels of lipid peroxidation, a marker for extent of oxidative stress. Ischemic rats exhibited a significant decrease in locomotion, grip strength and increase in beam walking latency. Tramadol attenuated the post ischemic motor impairment evidenced by improvement in the performance in sensorimotor tests. The extent of lipid peroxidation was significantly (p < 0.001) reduced by tramadol pretreatment which was higher in ischemic control. This study demonstrates the neuroprotective effect of tramadol against transient forebrain ischemia in rats.

Protective effect of hydroalcoholic extract of Mimusops elengi Linn. flowers against middle cerebral artery occlusion induced brain injury in rats

ETHNOPHARMACOLOGICAL RELEVANCE

In the traditional Indian and Thai system of medicine, Mimusops elengi Linn., flower is used as brain tonic and to calm anxiety and panic attacks.

AIM OF THE STUDY

The present study was designed to investigate the neuroprotective effect of hydroalcoholic extract of Mimusops elengi (ME) against cerebral ischemic reperfusion injury in rats.

MATERIALS AND METHODS

Male rats were pretreated with ME (100 and 200mg/kg) for seven days and focal cerebral ischemia was induced by middle cerebral artery occlusion (MCAO) method. After 60min of MCAO and 24h of reperfusion, a battery of behavioral tests assessed the extent of neurological deficits. Infarct volume and brain edema were measured in TTC stained brain sections and the extent of blood brain barrier (BBB) disruption was observed by Evan's blue extravasation. Oxidative and nitrative stress parameters were estimated in the brain homogenates. Further, simultaneous quantification of five polyphenolic biomarkers were done using HPLC.

RESULTS

Pretreatment with ME at doses of 100 and 200mg/kg significantly improved the neurobehavioral alterations and reduced the infarct volume, edema and extent of BBB disruption induced by ischemia reperfusion injury. It also prevented the alteration in the antioxidant status and reduced the nitrite levels when compared to ischemic animals. Further, HPLC studies revealed that ME contains five bioactive polyphenolic compounds.

CONCLUSIONS

These results clearly indicate the neuroprotective effect of ME against stroke like injury. The observed protective effect might be attributed to the polyphenolic compounds and their antioxidant and anti-inflammatory property.

Effects of continuous intravenous infusion of MCI-186 on functional recovery after spinal cord injury in rats

We investigated the effects of a free radical scavenger, MCI-186 (edaravone), on neuroprotection in the rat post-traumatic spinal cord using various doses and routes of administration. The injury was produced with a weight-drop device. Lipid peroxide formation in the spinal cord was measured using the thiobarbituric acid test for malonyldialdehyde (MDA). In the first experiment, MDA production in the untreated post-traumatic spinal cord reached peak values at 1 h post-trauma, and gradually decreased to control levels in 7 days. In the second experiment, rats received twice-daily injections (0, 1, 3, 5, 10, or 20 mg/kg) for 3 days. We found that 3 mg/kg was most effective functionally and histologically. In the third experiment, rats received a 3 mg/kg bolus + continuous infusion (0, 1.5, 2.4, or 3.0 mg/kg/h) for 1, 2, 4, and 8 h. We found that a 3 mg/kg bolus + infusion of 3.0 mg/kg/h was most effective for the inhibition of MDA production. In the fourth experiment, a 3 mg/kg bolus given once immediately after injury and twice daily for 3 days, a 3 mg/kg bolus + 3.0 mg/kg/h for 1 day, or a 3 mg/kg bolus + 3.0 mg/kg/h for 3 days were administered. The continuous infusion for 1 day showed significant improvement functionally and histologically, but continuous infusion at the same rate for another 2 days did not show any further improvement. To effectively reduce secondary neuronal damage, strong inhibition of free radical chain reactions at the early stage, particularly within the first 24 h post-trauma, is important.

Free radical scavenger, edaravone, reduces the lesion size of lacunar infarction in human brain ischemic stroke

Background

Although free radicals have been reported to play a role in the expansion of ischemic brain lesions, the effect of free radical scavengers is still under debate. In this study, the temporal profile of ischemic stroke lesion sizes was assessed for more than one year to evaluate the effect of edaravone which might reduce ischemic damage.

Methods

We sequentially enrolled acute ischemic stroke patients, who admitted between April 2003 and March 2004, into the edaravone(-) group (n = 83) and, who admitted between April 2004 and March 2005, into the edaravone(+) group (n = 93). Because, edaravone has been used as the standard treatment after April 2004 in our hospital. To assess the temporal profile of the stroke lesion size, the ratio of the area [T2-weighted magnetic resonance images (T2WI)/iffusion-weighted magnetic resonance images (DWI)] were calculated. Observations on T2WI were continued beyond one year, and observational times were classified into subacute (1-2 months after the onset), early chronic (3-6 month), late chronic (7-12 months) and old (≥13 months) stages. Neurological deficits were assessed by the National Institutes of Health Stroke Scale upon admission and at discharge and by the modified Rankin Scale at 1 year following stroke onset.

Results

Stroke lesion size was significantly attenuated in the edaravone(+) group compared with the edaravone(-) group in the period of early and late chronic observational stages. However, this reduction in lesion size was significant within a year and only for the small-vessel occlusion stroke patients treated with edaravone. Moreover, patients with small-vessel occlusion strokes that were treated with edaravone showed significant neurological improvement during their hospital stay, although there were no significant differences in outcome one year after the stroke.

Conclusion

Edaravone treatment reduced the volume of the infarct and improved neurological deficits during the subacute period, especially in the small-vessel occlusion strokes.

Consistent injury to medium spiny neurons and white matter in the mouse striatum after prolonged transient global cerebral ischemia

A reproducible transient global cerebral ischemia (tGCI) mouse model has not been fully established. Although striatal neurons and white matter are recognized to be vulnerable to ischemia, their injury after tGCI in mice has not been elucidated. The purpose of this study was to evaluate injuries to striatal neurons and white matter after tGCI in C57BL/6 mice, and to develop a reproducible tGCI model. Male C57BL/6 mice were subjected to tGCI by bilateral common carotid artery occlusion (BCCAO). Mice whose cortical cerebral blood flow after BCCAO decreased to less than 13% of the pre-ischemic value were used. Histological analysis showed that at 3 days after 22 min of BCCAO, striatal neurons were injured more consistently than those in other brain regions. Quantitative analysis of cytochrome c release into the cytosol and DNA fragmentation in the striatum showed consistent injury to the striatum. Immunohistochemistry and Western blot analysis revealed that DARPP-32-positive medium spiny neurons, the majority of striatal neurons, were the most vulnerable among the striatal neuronal subpopulations. The striatum (especially medium spiny neurons) was susceptible to oxidative stress after tGCI, which is probably one of the mechanisms of vulnerability. SMI-32 immunostaining showed that white matter in the striatum was also consistently injured 3 days after 22 min of BCCAO. We thus suggest that this is a tGCI model using C57BL/6 mice that consistently produces neuronal and white matter injury in the striatum by a simple technique. This model can be highly applicable for elucidating molecular mechanisms in the brain after global ischemia.

Protective effects of edaravone on experimental spinal cord injury in rats

BACKGROUND

Spinal cord injury (SCI) is a leading cause of morbidity and mortality among youth and adults. Secondary injury mechanisms within the spinal cord (SC) are well known to cause deterioration after an acute impact. Free radical scavengers are among the most studied agents in animal models of SCI. Edaravone is a scavenger of hydroxyl radicals.

METHODS

We aimed to measure and compare the effects of both methylprednisolone and edaravone on tissue and on serum concentrations of nitric oxide (NO), malondialdehyde (MDA) levels, superoxide dismutase (SOD) activity, glutathione peroxidase (GSH-Px) activity, and tissue total antioxidant capacity (TAC) in rats with SCI. SCI was induced in four groups of Wistar albino rats by a weight-drop method. The neurological function of the rats was periodically tested. At the end of the experiment, blood samples were collected, and SC tissue samples were harvested for biochemical evaluation.

RESULTS

The tissue level of NO was decreased in the edaravone-treated group compared with the no-treatment group (p < 0.05). The tissue levels of SOD and GSH-Px were higher in the edaravone-treated group than in the no-treatment group (p < 0.05). The serum levels of NO were lower in the edaravone-treated and methylprednisolone-treated groups than in the no-treatment group (p < 0.05). The serum levels of SOD in the edaravone-treated group did not differ from those of any other group. The serum levels of MDA in the edaravone-treated and no-treatment groups were higher than in the two other groups (p < 0.05). Tissue levels of MDA in the edaravone-treated group were lower than in the no-treatment group (p < 0.05). Tissue levels of TAC in the edaravone-treated group were higher than in the no-treatment and methylprednisolone-treated groups (p < 0.05). The neurological outcome scores of the animals in treatment groups did not depict any statistically significant improvement in motor functions. However, edaravone seemed to prevent further worsening of the immediate post-SCI neurological status.

CONCLUSION

Our biochemical analyses indicate that edaravone is capable of blunting the increased oxidative stress that follows SCI. We show, for the first time, that edaravone enhances the TAC in SC tissue. This beneficial effect of edaravone on antioxidant status may act to minimize the secondary neurological damage that occurs during the acute phase after SCI.

Neuroprotective effect of Artemisia absinthium L. on focal ischemia and reperfusion-induced cerebral injury

ETHNOPHARMACOLOGICAL RELEVANCE

Artemisia absinthium L. has long been used as traditional herbal medicine in China, Europe and Pakistan for the treatment of gastric pain, cardiac stimulation, to improve memory and for the restoration of declining mental function.

AIM OF THE STUDY

The present study was designed to investigate the potential protective effects of Artemisia absinthium on cerebral oxidative stress and damage as well as behavioral disturbances induced by cerebral ischemia and reperfusion injury in rats.

MATERIALS AND METHODS

Focal ischemia and reperfusion were induced by middle cerebral artery occlusion (MCAO) for 90 min, followed by 24 h reperfusion. MCAO led to significant rise in infarct size and lipid peroxidation, and depletion in glutathione content, superoxide dismutase and catalase activity in brain. Further, behavioral deficits like motor incoordination and impairment of short-term memory were also significantly impaired by MCAO as compared with sham group.

RESULTS

The brain oxidative stress and damage, and behavioral deficits were significantly attenuated by pre-treatment with the methanol extract of Artemisia absinthium (100 mg/kg and 200 mg/kg, p.o.).

CONCLUSION

These findings suggested that Artemisia absinthium is neuroprotective and may prove to be useful adjunct in the treatment of stroke.