Pharmacological approaches to acute ischaemic stroke: reperfusion certainly, neuroprotection possibly

Targeting pyroptosis to treat ischemic stroke: From molecular pathways to treatment strategy

Ischemic stroke is the primary reason for human disability and death, but the available treatment options are limited. Hence, it is imperative to explore novel and efficient therapies. In recent years, pyroptosis (a pro-inflammatory cell death characterized by inflammation) has emerged as an important pathological mechanism in ischemic stroke that can cause cell death through plasma membrane rupture and release of inflammatory cytokines. Pyroptosis is closely associated with inflammation, which exacerbates the inflammatory response in ischemic stroke. The level of inflammasomes, GSDMD, Caspases, and inflammatory factors is increased after ischemic stroke, exacerbating brain injury by mediating pyroptosis. Hence, inhibition of pyroptosis can be a therapeutic strategy for ischemic stroke. In this review, we have summarized the relationship between pyroptosis and ischemic stroke, as well as a series of treatments to attenuate pyroptosis, intending to provide insights for new therapeutic targets on ischemic stroke.

Cross-talk between bioactive lipid mediators and the unfolded protein response in ischemic stroke

Ischemic cerebral stroke is a severe medical condition that affects about 15 million people every year and is the second leading cause of death and disability globally. Ischemic stroke results in neuronal cell death and neurological impairment. Current therapies may not adequately address the deleterious metabolic changes and may increase neurological damage. Oxygen and nutrient depletion along with the tissue damage result in endoplasmic reticulum (ER) stress, including the Unfolded Protein Response (UPR), and neuroinflammation in the affected area and cause cell death in the lesion core. The spatio-temporal production of lipid mediators, either pro-inflammatory or pro-resolving, decides the course and outcome of stroke. The modulation of the UPR as well as the resolution of inflammation promotes post-stroke cellular viability and neuroprotection. However, studies about the interplay between the UPR and bioactive lipid mediators remain elusive and this review gives insights about the crosstalk between lipid mediators and the UPR in ischemic stroke. Overall, the treatment of ischemic stroke is often inadequate due to lack of effective drugs, thus, this review will provide novel therapeutical strategies that could promote the functional recovery from ischemic stroke.

A feasibility and safety study of afamelanotide in acute stroke patients - an open label, proof of concept, phase iia clinical trial

BACKGROUND

Neuroprotective agents have the potential to improve the outcomes of revascularisation therapies in acute ischemic stroke patients (AIS) and in those unable to receive revascularisation. Afamelanotide, a synthetic α-melanocyte stimulating hormone analogue, is a potential novel neuroprotective agent. We set out to assess the feasibility and safety of afamelanotide for the first time in AIS patients.

METHODS

AIS patients within 24 h of onset, with perfusion abnormality on imaging (Tmax) and otherwise ineligible for revascularisation therapies were enrolled. Afamelanotide 16 mg implants were administered subcutaneously on Day 0 (D0, day of recruitment), D1 and repeated on D7 and D8, if not well recovered. Treatment emergent adverse events (TEAEs) and neurological assessments were recorded regularly up to D42. Magnetic resonance imaging (MRI) with FLAIR sequences were also performed on D3 and D9.

RESULTS

Six patients (5 women, median age 81, median NIHSS 6) were recruited. Two patients received 4 doses and four patients received 2. One patient (who received 2 doses), suffered a fatal recurrent stroke on D9 due to a known complete acute internal carotid artery occlusion, assessed as unrelated to the study drug. There were no other local or major systemic TEAEs recorded. In all surviving patients, the median NIHSS improved from 6 to 2 on D7. The median Tmax volume on D0 was 23 mL which was reduced to a FLAIR volume of 10 mL on D3 and 4 mL on D9.

CONCLUSIONS

Afamelanotide was well tolerated and safe in our small sample of AIS patients. It also appears to be associated with good recovery and radiological improvement of salvageable tissue which needs to be tested in randomized studies.

CLINICALTRIALS

GOV IDENTIFIER

NCT04962503, First posted 15/07/2021.

Pharmacological Inhibition of Class III Alcohol Dehydrogenase 5: Turning Remote Ischemic Conditioning Effective in a Diabetic Stroke Model

The restoration of cerebral blood flow (CBF) to achieve brain tissue oxygenation (PbtO₂) is the primary treatment for ischemic stroke, a significant cause of adult mortality and disability worldwide. Nitric oxide (NO) and its bioactive s-nitrosylated (SNO) reservoirs, such as s-nitrosoglutathione (GSNO), induce hypoxic vasodilation to enhance CBF during ischemia. The endogenous pool of SNOs/GSNO is enhanced via the activation of endothelial NO synthase (eNOS/NOS3) and by the suppression of class III alcohol dehydrogenase 5 (ADH5), also known as GSNO reductase (GSNOR). Remote ischemic conditioning (RIC), which augments NOS3 activity and SNO, is an emerging therapy in acute stroke. However, RIC has so far shown neutral effects in stroke clinical trials. As the majority of stroke patients are presented with endothelial dysfunctions and comorbidities, we tested the hypothesis that NOS3 dysfunction and diabetes will abolish the protective effects of RIC therapy in stroke, and the prior inhibition of GSNOR will turn RIC protective. Our data demonstrate that RIC during thrombotic stroke failed to enhance the CBF and the benefits of thrombolysis in NOS3 mutant (NOS3^+/−) mice, a genetic model of NOS3 dysfunction. Interestingly, thrombotic stroke in diabetic mice enhanced the activity of GSNOR as early as 3 h post-stroke without decreasing the plasma nitrite (NO₂⁻). In thrombotic stroke, neither a pharmacological inhibitor of GSNOR (GRI) nor RIC therapy alone was protective in diabetic mice. However, prior treatment with GRI followed by RIC enhanced the CBF and improved recovery. In a reperfused stroke model, the GRI–RIC combination therapy in diabetic mice augmented PbtO₂, a translatory signature of successful microvascular reflow. In addition, RIC therapy unexpectedly increased the inflammatory markers at 6 h post-stroke in diabetic stroke that were downregulated in combination with GRI while improving the outcomes. Thus, we conclude that preexisting NOS3 dysfunctions due to comorbidities may neutralize the benefits of RIC in stroke, which can be turned protective in combination with GRI. Our findings may support the future clinical trial of RIC in comorbid stroke. Further studies are warranted to test and develop SNO reservoirs as the blood-associated biomarker to monitor the response and efficacy of RIC therapy in stroke.

Neuroprotective approach in acute ischemic stroke: A systematic review of clinical and experimental studies

Ischemic stroke is a disease with worldwide economic and social negative effects. It is a serious disease with high disability and mortality. Ionic imbalance, excitotoxicity, oxidative stress, and inflammation are induced during and after ischemic stroke. Cellular dysfunction, apoptosis, and necrosis are activated directly or indirectly mechanisms. The studies about neuroprotection in neurodegenerative diseases have increased in recent years. Data about the mechanisms of progressive molecular improvement in the brain tissue are increasing in acute ischemic stroke. Based on these data, preclinical and clinical studies on new neuroprotective treatments are being designed. An effective neuroprotective strategy can prolong the indication period of recanalization treatments in the acute stage of ischemic stroke. In addition, it can reduce neuronal necrosis and protect the brain against ischemia-related reperfusion injury. The current review has evaluated the recent clinical and experimental studies. The molecular mechanism of each of the neuroprotective strategies is also summarized. This review may help develop future strategies for combination treatment to protect the cerebral tissue from ischemia-reperfusion injury.

Neuroprotection of everolimus against focal cerebral ischemia-reperfusion injury in rats

BACKGROUND

Mammalian target of rapamycin (mTOR) is a serine/threonine kinase that regulates cell growth and metabolism and integrates various signals under physiological and pathological conditions. Altered signaling of mTOR has been shown to play pathogenic roles in ischemic stroke. In the present study, the protective effect of everolimus, the selective mTOR inhibitor, in the middle cerebral artery occlusion (MCAO) model of ischemic stroke was evaluated.

METHODS

Wistar rats were exposed to MCAO (30 min) followed by reperfusion for 24 h. Everolimus (100, and 500 µg/kg) was administered at the time of reperfusion, intraperitoneally. 24 h post operation, the neurological function, infarct volume, histopathological alterations and the markers of oxidative stress including superoxide dismutase (SOD) activity, malondialdehyde (MDA), and total thiol levels were analyzed in the peri-infarct region.

RESULTS

In the rats subjected to MCAO, everolimus ameliorated neurological deficits, neuronal cell loss, and infarct volume, as compared to the stroke group. Also, everolimus significantly increased SOD activity and total thiol content, while markedly decreased the MDA level, as compared to MCAO group.

CONCLUSION

Single-dose administration of everolimus significantly improved neurological deficits and inhibited cortical cell loss by enhancing redox status, subsequently protected cerebral ischemia-reperfusion injury in rats.

Anti-embolic and anti-oxidative effects of a novel (E)-4-amino-N'-(1-(7-hydroxy-2-oxo-2H-chromen-3-yl) ethylidene) benzohydrazide against isoproterenol and vitamin-K induced ischemic stroke

This study aimed to evaluate the cerebroprotective potential of a novel synthetic coumarin, (E)-4-amino-N'-(1-(7-hydroxy-2-oxo-2H-chromen-3-yl)ethylidene) benzohydrazide noted (HC) against a pharmaceutically induced ischemic stroke in experimental male Wistar rats. Animals were randomly allocated into four groups: control, Stroke, Stroke + Ace (acenocoumarol) and Stroke + HC-treated group for 7 days. Our results showed that stroke group evidenced atrial flutter, significant cardiac hypertrophy (+23%) and increase in plasma level of troponin-T, with disturbance in plasma ionic levels and rise in fibrinogen rate and oxidative damages in heart and brain. Moreover, the histological findings revealed myocardium necrosis, cardiac cavity thrombi and brain injury as compared to normal rats. However, HC-treatment significantly prevents the embolic process, improves cerebral damages and mitigates the oxidative stress markers in stroke rats. Overall, HC is endowed with a thrombolytic potential against MI and stroke in such severe conditions through an anti-vit K (AVK) mechanism.

The Mitochondrial mitoNEET Ligand NL-1 Is Protective in a Murine Model of Transient Cerebral Ischemic Stroke

PURPOSE

Therapeutic strategies to treat ischemic stroke are limited due to the heterogeneity of cerebral ischemic injury and the mechanisms that contribute to the cell death. Since oxidative stress is one of the primary mechanisms that cause brain injury post-stroke, we hypothesized that therapeutic targets that modulate mitochondrial function could protect against reperfusion-injury after cerebral ischemia, with the focus here on a mitochondrial protein, mitoNEET, that modulates cellular bioenergetics.

METHOD

In this study, we evaluated the pharmacology of the mitoNEET ligand NL-1 in an in vivo therapeutic role for NL-1 in a C57Bl/6 murine model of ischemic stroke.

RESULTS

NL-1 decreased hydrogen peroxide production with an IC50 of 5.95 μM in neuronal cells (N2A). The in vivo activity of NL-1 was evaluated in a murine 1 h transient middle cerebral artery occlusion (t-MCAO) model of ischemic stroke. We found that mice treated with NL-1 (10 mg/kg, i.p.) at time of reperfusion and allowed to recover for 24 h showed a 43% reduction in infarct volume and 68% reduction in edema compared to sham-injured mice. Additionally, we found that when NL-1 was administered 15 min post-t-MCAO, the ischemia volume was reduced by 41%, and stroke-associated edema by 63%.

CONCLUSION

As support of our hypothesis, as expected, NL-1 failed to reduce stroke infarct in a permanent photothrombotic occlusion model of stroke. This report demonstrates the potential therapeutic benefits of using mitoNEET ligands like NL-1 as novel mitoceuticals for treating reperfusion-injury with cerebral stroke.

Transcriptomic and Metabolomic Profiling Reveals the Protective Effect of Acanthopanax senticosus (Rupr. & Maxim.) Harms Combined With Gastrodia elata Blume on Cerebral Ischemia-Reperfusion Injury

The effects of current treatment strategies used in ischemic stroke are weakened by cerebral ischemia-reperfusion (CIR) injury. Suitable treatment regimens targeting CIR injury are still lacking. Two herbs, namely, Acanthopanax senticosus (Rupr. & Maxim.) Harms (ASE) and Gastrodia elata Blume (GEB), have been used as traditional Chinese medicine and are indicated in the treatment of stroke and cerebrovascular diseases. However, there are no studies that report the effects of ASE combined with GEB in the treatment of CIR injury. In this study, we used the Zea Longa method to induce CIR injury in male Wistar rats. Results of the pharmacodynamic studies revealed that co-administration of ASE and GEB may improve neuronal injury and prevent neuronal apoptosis by reducing oxidative stress and inflammation, and also help prevent CIR injury. On the basis of our hypothesis, we combined the results from transcriptomic and metabonomic analyses and found that ASE and GEB could prevent CIR injury by targeting phenylalanine, pyrimidine, methionine, and sphingolipid metabolism. Therefore, our study provides the basis for the compatibility and efficacy of ASE and GEB.

Effects of Acanthopanax senticosus (Rupr. & Maxim.) Harms on cerebral ischemia-reperfusion injury revealed by metabolomics and transcriptomics

ETHNOPHARMACOLOGICAL RELEVANCE

Cerebral ischemia-reperfusion (CIR) injury is one of the main diseases leading to death and disability. Acanthopanax senticosus (Rupr. & Maxim.) Harms (AS), also known as Panax ginseng, has neuroprotective effects on anti-CIR injury. However, the underlying molecular mechanism of its therapeutic effects is not clear.

AIM OF THE STUDY

To systematically study and explore the mechanism of Acanthopanax senticosus (Rupr. & Maxim.) Harms extract (ASE) in the treatment of CIR injury based on metabolomics and transcriptomics.

MATERIALS AND METHODS

The pharmacological basis of ASE in the treatment of CIR was evaluated, and samples were used in plasma metabolomics and brain tissue transcriptomics to reveal potential biomarkers. Finally, according to online database, we analyzed biomarkers identified by the two technologies, explained reasons for the therapeutic effect of ASE, and identify therapeutic targets.

RESULTS

A total of 53 differential metabolites (DMs) were identified in plasma and 3138 differentially expressed genes (DEGs) were identified in brain tissue from three groups of rats, including sham, ischemia-reperfusion (I/R), and ASE groups. Enrichment analysis showed that Nme6, Tk1, and Pold1 that are involved in the production of deoxycytidine and thymine were significantly up-regulated and Dck was significantly down-regulated by the intervention with ASE. These findings indicated that ASE participates in the pyrimidine metabolism by significantly regulating the balance between dCTP and dTTP. In addition, ASE repaired and promoted the lipid metabolism in rats, which might be due to the significant expression of Dgkz, Chat, and Gpcpd1.

CONCLUSIONS

The findings of this study suggest that ASE regulates the significant changes in gene expression in metabolites pyrimidine, and lipid metabolism in CIR rats and plays an active role in the treatment of CIR injury through multiple targets and pathways.

Donepezil attenuates injury following ischaemic stroke by stimulation of neurogenesis, angiogenesis, and inhibition of inflammation and apoptosis

Donepezil has proven to be an effective drug to reduce neuronal death and subsequently injury in neurodegenerative diseases. The current study evaluated the neuroprotective effects of donepezil in a rat model of ischaemic stroke and explored possible mechanisms which by this drug may reduce cell death. Temporary middle cerebral artery occlusion (tMCAO) was exerted for 45 min to induce ischaemic stroke. The animals were assigned into five groups: sham, control, and three groups treated with different doses of donepezil. Donepezil was intraperitoneally (IP) injected 4 h after reperfusion for 10 consecutive days. Infarct size was determined using TTC staining. The expression of proteins was evaluated using immunohistochemistry assays. Compared with the control group, infarct size was significantly reduced in tMCAO rats treated with different doses of donepezil. Moreover, our results showed significant decreased expression levels of apoptotic markers and pro-inflammatory mediators after treatment with different doses of donepezil for 10 days (P < 0.05). Likewise, significant increase of brain-derived neurotrophic factor (BDNF) and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) proteins were found in tMCAO rats treated with donepezil compared with the control group (P < 0.05). Collectively, our findings show the validity of donepezil as a new therapeutic agent for attenuation of injury following ischaemic stroke through attenuation of inflammation and improvement of mitochondrial function, neurogenesis, and angiogenesis.

Lasting metabolic effect of a high-fructose diet on global cerebral ischemia

Introduction: Obesity is a public health problem that is associated with cerebrovascular diseases, such as ischemic stroke. The coexistence of obesity with cerebral ischemia has been suggested to be considerably detrimental to the neurological system. Objective: Hence, in this study, we evaluated the long-term effects of a 20% high fructose diet (HFD) and global cerebral ischemia on neurological, cognitive and emotional performance in three-month-old male Wistar rats. Results: Our results demonstrated that fructose intake led to increases in body weight and blood glucose, as well as reduced insulin sensitivity. The co-morbidity of fructose intake and cerebral ischemia resulted to hyperlipidemia, as well as increases in liver and adipocyte damage, which worsened neurological performance and resulted in alterations in learning and emotional skills at two weeks post-ischemia. No significant biochemical changes in autophagy and plasticity markers at the late stage of ischemia were observed. Conclusion: These results suggested that obesity causes a lasting effect on metabolic disorders that can contribute to increased neurological impairment after cerebral ischemia.

Aerobic exercise attenuates neurodegeneration and promotes functional recovery - Why it matters for neurorehabilitation & neural repair

Aerobic exercise facilitates optimal neurological function and exerts beneficial effects in neurologic injuries. Both animal and clinical studies have shown that aerobic exercise reduces brain lesion volume and improves multiple aspects of cognition and motor function after stroke. Studies using animal models have proposed a wide range of potential molecular mechanisms that underlie the neurological benefits of aerobic exercise. Furthermore, additional exercise parameters, including time of initiation, exercise dosage (exercise duration and intensity), and treatment modality are also critical for clinical application, as identifying the optimal combination of parameters will afford patients with maximal functional gains. To clarify these issues, the current review summarizes the known neurological benefits of aerobic exercise under both physiological and pathological conditions and then considers the molecular mechanisms underlying these benefits in the contexts of stroke-like focal cerebral ischemia and cardiac arrest-induced global cerebral ischemia. In addition, we explore the key roles of exercise parameters on the extent of aerobic exercise-induced neurological benefits to elucidate the optimal combination for aerobic exercise intervention. Finally, the current challenges for aerobic exercise implementation after stroke are discussed.

Animal models of cerebral ischemia: A review

Stroke seriously threatens human health because of its characteristics of high morbidity, disability, recurrence, and mortality, thus representing a heavy financial and mental burden to affected families and society. Many preclinical effective drugs end in clinical-translation failure. Animal models are an important approach for studying diseases and drug effects, and play a central role in biomedical research. Some details about animal models of cerebral ischemia have not been published, such as left-/right-sided lesions or permanent cerebral ischemia/cerebral ischemia-reperfusion. In this review, ischemia in the left- and right-hemisphere in patients with clinical stroke and preclinical studies were compared for the first time, as were the mechanisms of permanent cerebral ischemia and cerebral ischemia-reperfusion in different phases of the disease. The results showed that stroke in the left hemisphere was more common in clinical patients, and that most patients with stroke failed to achieve successful recanalization. Significant differences were detected between permanent cerebral ischemia and cerebral ischemia-reperfusion models in the early, subacute, and recovery phases. Therefore, it is recommended that, with the exception of the determined experimental purpose or drug mechanism, left-sided permanent cerebral ischemia animal models should be prioritized, as they would be more in line with the clinical scenario and would promote clinical translation. In addition, other details regarding the preoperative management, surgical procedures, and postoperative care of these animals are provided, to help establish a precise, effective, and reproducible model of cerebral ischemia model and establish a reference for researchers in this field.

Are researchers moving away from animal models as a result of poor clinical translation in the field of stroke? An analysis of opinion papers

Objectives

Despite decades of research using animals to develop pharmaceutical treatments for patients who have had a stroke, few therapeutic options exist. The vast majority of interventions successful in preclinical animal studies have turned out to have no efficacy in humans or to be harmful to humans. In view of this, we explore whether there is evidence of a move away from animal models in this field.

Methods

We used an innovative methodology, the analysis of opinion papers. Although we took a systematic approach to literature searching and data extraction, this is not a systematic review because the study involves the synthesis of opinions, not research evidence. Data were extracted from retrieved papers in chronological order and analysed qualitatively and descriptively.

Results

Eighty eligible papers, published between 1979 and 2018, were identified. Most authors were from academic departments of neurology, neuroscience or stroke research. Authors agreed that translational stroke research was in crisis. They held diverse views about the causes of this crisis, most of which did not fundamentally challenge the use of animal models. Some, however, attributed the translational crisis to animal–human species differences and one to a lack of human in vitro models. Most of the proposed solutions involved fine-tuning animal models, but authors disagreed about whether such modifications would improve translation. A minority suggested using human in vitro methods alongside animal models. One proposed focusing only on human in vitro methods.

Conclusion

Despite recognising that animal models have been unsuccessful in the field of stroke, most researchers exhibited a strong resistance to relinquishing them. Nevertheless, there is an emerging challenge to the use of animal models, in the form of human-focused in vitro approaches. For the sake of stroke patients there is an urgent need to revitalise translational stroke research and explore the evidence for these new approaches.

Insulin-Like Growth Factor-1 Is Neuroprotective in Aged Rats With Ischemic Stroke

Post-stroke systemic injections of insulin-like growth factor-1 (IGF-1) exert neuroprotective effects in rats. In the current study, we aimed to test the efficacy of IGF-1 neuroprotection in aged rats (24–25 months old) and to compare the results with adult rats (6–7 months old). Furthermore, we addressed putative differences in microglial responses to IGF-1 in adult and aged rats. Rats were subjected to ischemic stroke while they were conscious by infusing endothelin-1 (Et-1) through a guide cannula that was implemented in the vicinity of the middle cerebral artery (MCA). Rats were given subcutaneous injections of IGF-1 (1 mg/kg) at 30 min and 120 min after the insult. Post-stroke IGF-1 treatment reduced the infarct size by 34% and 38% in aged and adult rats, respectively. The IGF-1 treated adult rats also showed significant improvement in sensorimotor function following stroke, while this function was not significantly affected in aged rats. Furthermore, aged rats displayed exaggerated activation of microglia in the ischemic hemisphere. Significant reduction of microglial activation by IGF-1 was only detected at specific regions in the ipsilateral hemisphere of adult rats. We show that IGF-1 reduced infarct size in aged rats with an ischemic stroke. It remains to be established, however, whether the age-related changes in microglial function affect the improvement in behavioral outcomes.

Neuroprotective effect of ginkgetin in experimental cerebral ischemia/reperfusion via apoptosis inhibition and PI3K/Akt/mTOR signaling pathway activation

BACKGROUND

Ginkgetin, extracted from Ginkgo biloba L leaves, has been demonstrated to have potential anti-inflammatory and immune-suppressive properties. But the neuroprotective effect and potential mechanisms of ginkgetin on cerebral ischemia/reperfusion (IR) injury remain unclear.

METHODS

In this research, we studied the neuroprotective effect of ginkgetin in the middle part of the middle cerebral artery occlusion/reperfusion rat model, by analyzing the apoptosis of brain tissues harvested from treatment groups and control groups using the terminal deoxynucleotidyl transferase dUTP nick-end labeling and apoptosis assays. In addition, we detected the association of the neuroprotective effect of ginkgetin with apoptosis inhibition via the activation of the phosphatidylinositol-3-kinase/Akt/mammalian target of rapamycin (PI3K/Akt/mTOR) signaling pathway using Western blot analysis.

RESULTS

Our results showed that administration of ginkgetin remarkably reduced brain infarction volumes and neurologic deficits; in addition, reducing apoptotic cell numbers, downregulating the levels of cleaved caspase-3 and Bax, and upregulating the level of Bcl-2 in rats subjected to IR injury in a dose-dependent manner. Moreover, high-dose ginkgetin treatment (100 mg/kg) significantly increased the phosphorylations of Akt and mTOR. Blocking of PI3K by LY294002 clearly decreased its antiapoptotic effect and reduced both Akt and mTOR phosphorylation levels.

CONCLUSIONS

Taken together, these results for the first time suggest that ginkgetin antagonizes cerebral IR-induced injury by inhibiting apoptosis in rats, and this effect was attenuated by the activation of PI3K/Akt/mTOR signaling pathway.

A peptide mimetic of tyrosine phosphatase STEP as a potential therapeutic agent for treatment of cerebral ischemic stroke

Extensive research over the last two decades has advanced our understanding of the pathophysiology of ischemic stroke. However, current pharmacologic therapies are still limited to rapid reperfusion using thrombolytic agents, and neuroprotective approaches that can reduce the consequences of ischemic and reperfusion injury, are still not available. To bridge this gap, we have evaluated the long-term efficacy and therapeutic time window of a novel peptide-based neuroprotectant TAT-STEP, derived from the brain-enriched and neuron-specific tyrosine phosphatase STEP. Using a rat model of transient middle cerebral artery occlusion (90 min), we show that a single intravenous administration of the peptide at the onset of reperfusion (early) or 6 h after the onset of the insult (delayed) reduces mortality rate. In the surviving rats, MRI scans of the brain at days 1, 14 and 28 after the insult show significant reduction in infarct size and improvement of structural integrity within the infarcted area following peptide treatment, regardless of the time of administration. Behavioral assessments show significant improvement in normal gait, motor coordination, sensory motor function and spatial memory following early or delayed peptide treatment. The study establishes for the first time the therapeutic potential of a tyrosine phosphatase in ischemic brain injury.

Ultrasound-Enhanced Protective Effect of Tetramethylpyrazine via the ROS/HIF-1A Signaling Pathway in an in Vitro Cerebral Ischemia/Reperfusion Injury Model

Reactive oxygen species-induced oxidative stress is an important pathophysiological process during cerebral ischemia/reperfusion (I/R) injury. It has been reported that the protective effect of tetramethylpyrazine (TMP) against cerebral I/R injury can be significantly improved by its combination with ultrasound exposure. However, the molecular mechanisms and signaling pathways underlying the synergistic protective effect remain unclear. In the present work, the damage induced by I/R injury was modeled by glutamate-induced toxicity to pheochromocytoma (PC12) cells. The ultrasound-enhanced protective effect of TMP was systemically investigated by measuring variations in cell viability, cell migration and levels of intracellular reactive oxygen species, the oxidative stress-related protein glutathione, apoptosis-related proteins (caspase-8, -9 and -3), as well as expression of related genes (hypoxia-inducible factor-1a, p53, murine double minute2). The results suggest that the ultrasound-enhanced protective effect of TMP against cerebral I/R injury might act via the reactive oxygen species/hypoxia-inducible factor-1a signaling pathway, and an appropriate ultrasound intensity should be selected to achieve an optimal synergistic neuroprotective effect.

Herbal Medicine in Ischemic Stroke: Challenges and Prospective

Herbal medicines, mainly of plant source, are invaluable source for the discovery of new therapeutic agents for all sorts of human ailments. The complex pathogenesis of stroke and multifactorial effect of herbal medicine and their active constituents may suggest the promising future of natural medicine for stroke treatment. Anti-oxidant, anti-inflammatory, anti-apoptotic, neuroprotective and vascular protective effect of herbal medicines are believed to be efficacious in stroke treatment. Herbs typically have fewer reported side effects than allopathic medicine, and may be safer to use over longer period of time. Herbal medicines are believed to be more effective for the longstanding health complaints, such as stroke. Several medicinal plants and their active constituents show the promising results in laboratory research. However failure in transformation of laboratory animal research to the clinical trials has created huge challenge for the use of herbal medicine in stroke. Until and unless scientifically comprehensive evidence of the efficacy and safety of herbal medicine in ischemic stroke patients is available, efforts should be made to continue implementing treatment strategies of proven effectiveness. More consideration should be paid to natural compounds that can have extensive therapeutic time windows, perfect pharmacological targets with few side effects. Herbal medicine has excellent prospective for the treatment of ischemic stroke, but a lot of effort should be invested to transform the success of animal research to human use.

Refocusing Neuroprotection in Cerebral Reperfusion Era: New Challenges and Strategies

Pathophysiological processes of stroke have revealed that the damaged brain should be considered as an integral structure to be protected. However, promising neuroprotective drugs have failed when translated to clinical trials. In this review, we evaluated previous studies of neuroprotection and found that unsound patient selection and evaluation methods, single-target treatments, etc., without cerebral revascularization may be major reasons of failed neuroprotective strategies. Fortunately, this may be reversed by recent advances that provide increased revascularization with increased availability of endovascular procedures. However, the current improved effects of endovascular therapy are not able to match to the higher rate of revascularization, which may be ascribed to cerebral ischemia/reperfusion injury and lacking of neuroprotection. Accordingly, we suggest various research strategies to improve the lower therapeutic efficacy for ischemic stroke treatment: (1) multitarget neuroprotectant combinative therapy (cocktail therapy) should be investigated and performed based on revascularization; (2) and more efforts should be dedicated to shifting research emphasis to establish recirculation, increasing functional collateral circulation and elucidating brain–blood barrier damage mechanisms to reduce hemorrhagic transformation. Therefore, we propose that a comprehensive neuroprotective strategy before and after the endovascular treatment may speed progress toward improving neuroprotection after stroke to protect against brain injury.

Method development and application for multi-component quantification in rats after oral administration of Longxuetongluo Capsule by UHPLC-MS/MS

Although wide applications towards ischemic stroke in clinic, the therapeutic materials of Longxuetongluo Capsule (LTC) that is composed of total phenolic extract of Chinese dragon's blood, are still largely unclear. Exposure pattern characterization of those drug-derived components in vivo, notably in circulation system has been recommended as a viable approach to disclose the effective components of a given herbal medicine. Herein, we aimed to develop a robust method being capable of multi-component quantification in either rat plasma or tissues following oral administration of LTC, and to clarify the kinetic profiles of 11 primary drug-derived phenolic derivatives. Proteins precipitation was carried out for the plasma as well as homogenized tissue samples with acetonitrile. Chromatographic separations were achieved using UHPLC equipped with a shim-pack XR-ODS II column, and confidence-enhanced detection was accomplished through the joint employment of selected-reaction monitoring and tandem mass spectrometry (SRM-MS/MS) on a hybrid triple quadrupole-linear ion trap mass spectrometer. Diverse validation assays proved the method to be sensitive, precise, and rapid for simultaneous determination of those 11 components. Pharmacokinetic and tissue distribution investigations were subsequently conducted in rat after a single 500 mg/kg oral dose. Rapid absorption (T_max, 11.53-68.27 min) and elimination (T_1/2, 6.893-57.90 min) occurred for all analytes-of-interest. Extensive occurrences were observed for 7,4'-dihydroxy-5-methoxyhomoisoflavanone (C_max, 340.0 ng/mL), thevetiaflavone (C_max, 42.86 ng/mL), 5,7,4'-trihydroxyhomoisoflavanone (C_max, 41.55 ng/mL), and pterostilbene (C_max, 25.49 ng/mL) in plasma. Significant distributions occurred for all analytes in the liver as well as kidney, and several compounds could be found in brain. The findings described are envisioned to provide promising information for the in-depth clarification of the therapeutic entities, and also to offer a practical approach for therapeutic drug monitoring of LTC in clinic.

An In Vitro Oxygen-Glucose Deprivation Model for Studying Ischemia-Reperfusion Injury of Neuronal Cells

Ischemia-reperfusion syndromes of the heart and brain are the leading cause of death and long-term disability worldwide. Development of effective treatments for myocardial infarction, stroke, cardiac arrest and their sequelae requires preclinical models that replicate specific features of ischemia-reperfusion. The complexities of intact animals, including the integrated function of organ systems, autonomic innervation and endocrine factors, often preclude detailed study of specific components of ischemia-reperfusion injury cascades. Ischemia represents the interruption of metabolic fuel and oxygen delivery to support cellular oxidative metabolism; reintroduction of oxygen upon reperfusion of ischemic tissue triggers oxidative stress which initiates the reperfusion injury cascade culminating in injury and death of cells and tissues. Thus, cultured cells subjected to hypoxia, fuel deprivation and reoxygenation replicate the cardinal features of ischemia-reperfusion, while accommodating interventions such as siRNA suppression of specific genes and pharmacological activation or inhibition of signaling cascades that are not feasible in more complex preparations, especially intact animals. This chapter describes an in vitro OGD-reoxygenation cell culture model, an excellent preparation to examine the cellular mechanisms mediating ischemia-reperfusion injury and/or cytoprotection.

Monocyte-lymphocyte cross-communication via soluble CD163 directly links innate immune system activation and adaptive immune system suppression following ischemic stroke

CD163 is a scavenger receptor expressed on innate immune cell populations which can be shed from the plasma membrane via the metalloprotease ADAM17 to generate a soluble peptide with lympho-inhibitory properties. The purpose of this study was to investigate CD163 as a possible effector of stroke-induced adaptive immune system suppression. Liquid biopsies were collected from ischemic stroke patients (n = 39), neurologically asymptomatic controls (n = 20), and stroke mimics (n = 20) within 24 hours of symptom onset. Peripheral blood ADAM17 activity and soluble CD163 levels were elevated in stroke patients relative to non-stroke control groups, and negatively associated with post-stroke lymphocyte counts. Subsequent in vitro experiments suggested that this stroke-induced elevation in circulating soluble CD163 likely originates from activated monocytic cells, as serum from stroke patients stimulated ADAM17-dependant CD163 shedding from healthy donor-derived monocytes. Additional in vitro experiments demonstrated that stroke-induced elevations in circulating soluble CD163 can elicit direct suppressive effects on the adaptive immune system, as serum from stroke patients inhibited the proliferation of healthy donor-derived lymphocytes, an effect which was attenuated following serum CD163 depletion. Collectively, these observations provide novel evidence that the innate immune system employs protective mechanisms aimed at mitigating the risk of post-stroke autoimmune complications driven by adaptive immune system overactivation, and that CD163 is key mediator of this phenomenon.

Multi-Targeting Andrographolide, a Novel NF-κB Inhibitor, as a Potential Therapeutic Agent for Stroke

A key focus in the field of drug discovery has been motivated by the neuroprotection of natural compounds. Cerebral ischemia is a multifaceted pathological process with a series of mechanisms, and a perspective for the development of neuroprotectants from traditional herbal medicine or natural products is a promising treatment for this disease. Natural compounds with the effects of anti-oxidation, anti-inflammation, anti-apoptosis, and neurofunctional regulation exhibit therapeutic effects on experimental ischemic brain injury. Conferring to the pharmacological mechanisms underlying neuroprotection, a study found that androgapholide, a diterpene lactone compound, exhibits varying degrees of neuroprotective activities in both in vitro and in vivo experimental models of stroke. The neuroprotective mechanisms of andrographolide are suggested as: (I) increasing nuclear factor E2-related factor 2-heme oxygenase (Nrf2-HO-1) expression through p38-mitogen activated protein kinase (MAPK) regulation, (II) inducing cerebral endothelial cells (CEC) apoptosis and caspase-3 activation, (III) down regulating Bax, inducible nitric oxide synthase (iNOS), and (IV) inhibiting hydroxyl radical (OH⁻) formation, and activating transcription factor NF-κB signaling pathways. Recently, several researchers have also been trying to unveil the principal mechanisms involved in the neuroprotective effects of andrographolide. Therefore, this review aims to summarize an overview on the neuroprotective effects of andrographolide and exemplifies the essential mechanisms involved. This paper can provide information that andrographolide drug discovery may be a promising strategy for the development of a novel class of neuroprotective drug.

Erythropoietin: Endogenous Protection of Ischemic Brain

The human brain requires uninterrupted delivery of blood-borne oxygen and nutrients to sustain its function. Focal ischemia, particularly, ischemic stroke, and global ischemia imposed by cardiac arrest disrupt the brain's fuel supply. The resultant ATP depletion initiates a complex injury cascade encompassing intracellular Ca²⁺ overload, glutamate excitotoxicity, oxido-nitrosative stress, extracellular matrix degradation, and inflammation, culminating in neuronal and astroglial necrosis and apoptosis, neurocognitive deficits, and even death. Unfortunately, brain ischemia has proven refractory to pharmacological intervention. Many promising treatments afforded brain protection in animal models of focal and global ischemia, but failed to improve survival and neurocognitive recovery of stroke and cardiac arrest patients in randomized clinical trials. The culprits are the blood-brain barrier (BBB) that limits transferral of medications to the brain parenchyma, and the sheer complexity of the injury cascade, which presents a daunting array of targets unlikely to respond to monotherapies. Erythropoietin is a powerful neuroprotectant capable of interrupting multiple aspects of the brain injury cascade. Preclinical research demonstrates erythropoietin's ability to suppress glutamate excitotoxicity and intracellular Ca²⁺ overload, dampen oxidative stress and inflammation, interrupt the apoptotic cascade, and preserve BBB integrity. However, the erythropoietin dosages required to traverse the BBB and achieve therapeutically effective concentrations in the brain parenchyma impose untoward side effects. Recent discoveries that hypoxia induces erythropoietin production within the brain and that neurons, astroglia, and cerebrovascular endothelium harbor membrane erythropoietin receptors, raise the exciting prospect of harnessing endogenous erythropoietin to protect the brain from the ravages of ischemia-reperfusion.

Different impairment of immune and inflammation functions in short and long-term after ischemic stroke

Ischemic stroke therapy and prognosis outcomes largely depend on the time periods after symptom onset. This study aims to explore the difference of global gene expression profiles and impairment of biological functions between short-term and long-term after stroke onset. We compared three short-term (3 h, 5 h and 24 h) and a long-term (6-month) gene expression levels by a multi-platform microarray data integration method. RankProd was used to calculate the differentially expressed genes between stroke patients and controls. DAVID Bioinformatics Resources was utilized to determine affected biological functions. Consensus cluster and hierarchical cluster methods were employed to compare the gene expression patterns of the commonly biological functions among these four time course groups. The results showed that severe impairment of inflammation and immune related functions in 5 h and 24 h after symptom onset. However, these functions were less affected in the 3 h and the 6-month groups. In addition, several key genes (CCL20, THBS1, EREG, and IL6 et al.) were dramatically down-regulated in 5 h and 24 h groups, whereas these genes showed no change or even a slight contrary expression in 3 h or 6-month groups. This study has identified the large differences of altered immune and inflammation functions based on gene levels between short and long-term after stroke onset. The findings provide valuable insight into the clinical practice and prognosis evaluation of ischemic stroke.

The identification and molecular mechanism of anti-stroke traditional Chinese medicinal compounds

Stroke is a worldwide epidemic disease with high morbidity and mortality. The continuously exploration of anti-stroke medicines and molecular mechanism has a long way to go. In this study, in order to screen candidate anti-stroke compounds, more than 60000 compounds from traditional Chinese medicine (TCM) database were computationally analyzed then docked to the 15 known anti-stroke targets. 192 anti-stroke plants for clinical therapy and 51 current anti-stroke drugs were used to validate docking results. Totally 2355 candidate anti-stroke compounds were obtained. Among these compounds, 19 compounds are structurally identical with 16 existing drugs in which part of them have been used for anti-stroke treatment. Furthermore, these candidate compounds were significantly enriched in anti-stroke plants. Based on the above results, the compound-target-plant network was constructed. The network reveals the potential molecular mechanism of anti-stroke for these compounds. Most of candidate compounds and anti-stroke plants are tended to interact with target NOS3, PSD-95 and PDE5A. Finally, using ADMET filter, we identified 35 anti-stroke compounds with favorable properties. The 35 candidate anti-stroke compounds offer an opportunity to develop new anti-stroke drugs and will improve the research on molecular mechanism of anti-stroke.

Anesthesia for Endovascular Approaches to Acute Ischemic Stroke

Involvement of the Anesthesiologist in the early stages of care for acute ischemic stroke patient undergoing endovascular treatment is essential. Anesthetic management includes the anesthetic technique (general anesthesia vs sedation), a matter of much debate and an area in need of well-designed prospective studies. The large numbers of confounding factors make the design of such studies a difficult process. A universally agreed point in the endovascular management of acute ischemic stroke is the importance of decreasing the time to revascularization. Hemodynamic and ventilatory management and implementation of neuroprotective modalities and treatment of acute procedural complications are important components of the anesthetic plan.

Neuroprotective effects of Danggui-Jakyak-San on rat stroke model through antioxidant/antiapoptotic pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Dangui-Jakyak-San (DJ) is a traditional Korean medicinal polyherb, prescribed typically in patients with insufficient blood supply in Eastern Asia. The DJ also has been reported to have neuroprotective effects in vitro and in vivo studies.

AIM OF STUDY

The therapeutic potential of DJ was examined in stroke rat model, in comparison with donepezil, a reversible acetylcholinesterase inhibitor.

MATERIALS AND METHODS

Ischemic stroke rat model was induced by surgery of permanent occlusion of middle cerebral artery (pMCAO). The model was orally administered with distilled water (pMCAO control), donepezil at 10mg/kg (Donepezil) and DJ at 200, 100 and 50mg/kg (DJ 200, DJ 100 and DJ 50, respectively). Sham had the same surgery excepting for the pMCAO, and it was administered with distilled water (sham control).

RESULTS

After the administration for 28 days, the groups of DJ exhibited dose-dependent reduction in infarct/defect volumes with improvement in sensorimotor and cognitive motor function, comparing to pMCAO control. The DJ treatments seemed to enhance antiapoptotic and antioxidant effects; increases in antiapoptotic expressions (STAT3 and Pim-1) and decreases in lipid peroxidation (MDA) together with increases in contents of endogenous antioxidant (GSH) and activities of antioxidant enzymes (catalase and SOD). The histopathological analyses revealed significant reduction in neuronal apoptosis (caspase-3 and PARP) and neuronal degradation with atrophy and degeneration, in the DJ treatments. Furthermore, the oxidative stresses (nitrotyrosine as an iNOS factor and 4-HNE as a marker of lipid peroxidation) were observed mild. Although the similar neuroprotective effects were observed, the body weight loss was scarcely alleviated in Donepezil comparing to pMCAO control.

CONCLUSION

These suggest that DJ ameliorate the neurological dysfunction of cerebral ischemia through augmentation of antioxidant defense system and up-regulation of STAT3 and Pim-1.

Protective effect of Naoxintong against cerebral ischemia reperfusion injury in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Naoxintong (NXT), a renowned traditional Chinese medicine in China, has been used for the treatment of acute and chronic cardio-cerebrovascular diseases in clinic for more than 20 years.

AIM OF THE STUDY

To evaluate the potential neuroprotective effect of NXT against ischemia reperfusion (I/R) injury in mice and investigate the underlying mechanisms.

MATERIALS AND METHODS

Focal cerebral I/R injury in adult male CD-1 mice was induced by transient middle cerebral artery occlusion (tMCAO) for 1h followed by reperfusion for 23h. Mice were randomly divided into five groups: Sham group; tMCAO group; Vehicle group; NXT-treated groups at doses of 0.36g/kg and 0.54g/kg. The effects of NXT on murine neurological function were estimated by neurological defect scores, infarct volume and brain water content at 24h after tMCAO. Immunohistochemistry and Western blot were used to detect the expression of LOX-1, pERK1/2 and NF-κB at 24h after tMCAO. qRT-PCR was used to detect the expression of LOX-1 and NF-κB at 24h after tMCAO.

RESULTS

Compared with Vehicle group, 0.54g/kg group of NXT significantly ameliorated neurological outcome, infarction volume and brain water content, decreased the expression of LOX-1, pERK1/2 and NF-κB (P<0.05).

CONCLUSION

NXT protected the mice brain against I/R injury, and this protection maybe associated with the down-regulation of LOX-1, pERK1/2 and NF-κB expression.

Cerebral collaterals and collateral therapeutics for acute ischemic stroke

Cerebral collaterals are vascular redundancies in the cerebral circulation that can partially maintain blood flow to ischemic tissue when primary conduits are blocked. After occlusion of a cerebral artery, anastomoses connecting the distal segments of the MCA with distal branches of the ACA and PCA (known as leptomeningeal or pial collaterals) allow for partially maintained blood flow in the ischemic penumbra and delay or prevent cell death. However, collateral circulation varies dramatically between individuals, and collateral extent is significant predictor of stroke severity and recanalization rate. Collateral therapeutics attempt to harness these vascular redundancies by enhancing blood flow through pial collaterals to reduce ischemia and brain damage after cerebral arterial occlusion. While therapies to enhance collateral flow remain relatively nascent neuroprotective strategies, experimental therapies including inhaled NO, transient suprarenal aortic occlusion, and electrical stimulation of the parasympathetic sphenopalatine ganglion show promise as collateral therapeutics with the potential to improve treatment of acute ischemic stroke.

Icariin attenuates cerebral ischemia-reperfusion injury through inhibition of inflammatory response mediated by NF-κB, PPARα and PPARγ in rats

Icariin (ICA), an active flavonoid extracted from Chinese medicinal herb Epimedii, has been reported to exhibit many pharmacological effects including alleviating brain injury. However, little is known about the protection of ICA on ischemic stroke. Hence, this study was designed to investigate the neuroprotective effect of ICA and explore its underlying mechanisms on ischemic stroke induced by cerebral ischemia-reperfusion (I/R) injury in rats. The animals were pretreated with ICA at doses of 10, 30mg/kg twice per day for 3 consecutive days followed by cerebral I/R injury induced by middle cerebral artery occlusion (MCAO) for 2h and reperfusion for 24h. Neurological function and infarct volume were observed at 24h after reperfusion, the protein expression levels of interleukin-1β (IL-1β), transforming growth factor-β1 (TGF-β1), PPARα and PPARγ, inhibitory κB-α (IκB-α) degradation and nuclear factor κB (NF-κB) p65 phosphorylation were detected by Western blot, respectively. It was found that pretreatment with ICA could decrease neurological deficit score, diminish the infarct volume, and reduce the protein levels of IL-1β and TGF-β1. Moreover, ICA suppressed IκB-α degradation and NF-κB activation induced by I/R. Furthermore, the present study also showed that ICA up-regulated PPARα and PPARγ protein levels. These findings suggest that ICA has neuroprotective effect on ischemic stroke in rats through inhibition of inflammatory responses mediated by NF-κB and PPARα and PPARγ.

Development of epilepsy after ischaemic stroke

For about 30% of patients with epilepsy the cause is unknown. Even in patients with a known risk factor for epilepsy, such as ischaemic stroke, only a subpopulation of patients develops epilepsy. Factors that contribute to the risk for epileptogenesis in a given individual generally remain unknown. Studies in the past decade on epilepsy in patients with ischaemic stroke suggest that, in addition to the primary ischaemic injury, existing difficult-to-detect microscale changes in blood vessels and white matter present as epileptogenic pathologies. Injury severity, location and type of pathological changes, genetic factors, and pre-injury and post-injury exposure to non-genetic factors (ie, the exposome) can divide patients with ischaemic stroke into different endophenotypes with a variable risk for epileptogenesis. These data provide guidance for animal modelling of post-stroke epilepsy, and for laboratory experiments to explore with increased specificity the molecular 'mechanisms, biomarkers, and treatment targets of post-stroke epilepsy in different circumstances, with the aim of modifying epileptogenesis after ischaemic stroke in individual patients without compromising recovery.

Methylene blue-induced neuronal protective mechanism against hypoxia-reoxygenation stress

Brain ischemia and reperfusion (I/R) injury occurs in various pathological conditions, but there is no effective treatment currently available in clinical practice. Methylene blue (MB) is a century-old drug with a newly discovered protective function in the ischemic stroke model. In the current investigation we studied the MB-induced neuroprotective mechanism focusing on stabilization and activation of hypoxia-inducible factor-1α (HIF-1α) in an in vitro oxygen and glucose deprivation (OGD)-reoxygenation model.

METHODS

HT22 cells were exposed to OGD (0.1% O2, 6h) and reoxygenation (21% O2, 24h). Cell viability was determined with the calcein AM assay. The dynamic change of intracellular O2 concentration was monitored by fluorescence lifetime imaging microscopy (FLTIM). Glucose uptake was quantified using the 2-[N-(7-Nitrobenz-2-Oxa-1,3-Diazol-4-yl)Amino]-2-Deoxy-d-Glucose (2-NBDG) assay. ATP concentration and glycolytic enzyme activity were examined by spectrophotometry. Protein content changes were measured by immunoblot: HIF-1α, prolyl hydroxylase 2 (PHD2), erythropoietin (EPO), Akt, mTOR, and PIP5K. The contribution of HIF-1α activation in the MB-induced neuroprotective mechanism was confirmed by blocking HIF-1α activation with 2-methoxyestradiol-2 (2-MeOE2) and by transiently transfecting constitutively active HIF-1α.

RESULTS

MB increases cell viability by about 50% vs. OGD control. Compared to the corresponding control, MB increases intracellular O2 concentration and glucose uptake as well as the activities of hexokinase and G-6-PDH, and ATP concentration. MB activates the EPO signaling pathway with a corresponding increase in HIF-1α. Phosphorylation of Akt was significantly increased with MB treatment followed by activation of the mTOR pathway. Importantly, we observed, MB increased nuclear translocation of HIF-1α vs. control (about three folds), which was shown by a ratio of nuclear:cytoplasmic HIF-1α protein content.

CONCLUSION

We conclude that MB protects the hippocampus-derived neuronal cells against OGD-reoxygenation injury by enhancing energy metabolism and increasing HIF-1α protein content accompanied by an activation of the EPO signaling pathway.

HO-1 Signaling Activation by Pterostilbene Treatment Attenuates Mitochondrial Oxidative Damage Induced by Cerebral Ischemia Reperfusion Injury

Ischemia reperfusion (IR) injury (IRI) is harmful to the cerebral system and causes mitochondrial oxidative stress. The antioxidant response element (ARE)-mediated antioxidant pathway plays an important role in maintaining the redox status of the brain. Heme oxygenase-1 (HO-1), combined with potent AREs in the promoter of HO-1, is a highly effective therapeutic target for protection against cerebral IRI. Pterostilbene (PTE), a natural dimethylated analog of resveratrol from blueberries, is a strong natural antioxidant. PTE has been shown to be beneficial for some nervous system diseases and may regulate HO-1 signaling. This study was designed to investigate the protective effects of PTE on cerebral IRI and to elucidate potential mechanisms underlying those effects. Mouse brains and cultured HT22 neuron cells were subjected to IRI. Prior to this procedure, the brains or cells were exposed to PTE in the absence or presence of the HO-1 inhibitor ZnPP or HO-1 small interfering RNA (siRNA). PTE conferred a cerebral protective effect, as shown by increased neurological scores, viable neurons and decreased brain edema as well as a decreased ion content and apoptotic ratio in vivo. PTE also increased the cell viability and decreased the lactate dehydrogenase (LDH) leakage and apoptotic ratio in vitro. ZnPP and HO-1 siRNA both blocked PTE-mediated cerebral protection by inhibiting HO-1 signaling and further inhibited two HO-1 signaling-related antioxidant molecules:

NAD(P)H

quinone oxidoreductase 1 (NQO1) and glutathione S-transferases (GSTs), which are induced by PTE. PTE also promoted a well-preserved mitochondrial membrane potential (MMP), mitochondria complex I activity, and mitochondria complex IV activity, increased the mitochondrial cytochrome c level, and decreased the cytosolic cytochrome c level. However, this PTE-elevated mitochondrial function was reversed by ZnPP or HO-1 siRNA treatment. In summary, our results demonstrate that PTE treatment attenuates cerebral IRI by reducing IR-induced mitochondrial oxidative damage through the activation of HO-1 signaling.