Role of Cyclooxygenase-2 in Relation to Nitric Oxide and Endothelin-1 on Pathogenesis of Cerebral Vasospasm After Subarachnoid Hemorrhage in Rabbit

The effects of nitric oxide in Alzheimer's disease

Alzheimer's disease (AD), the most prevalent cause of dementia, is a progressive neurodegenerative condition that commences subtly and inexorably worsens over time. Despite considerable research, a specific drug that can fully cure or effectively halt the progression of AD remains elusive. Nitric oxide (NO), a crucial signaling molecule in the nervous system, is intimately associated with hallmark pathological changes in AD, such as amyloid-beta deposition and tau phosphorylation. Several therapeutic strategies for AD operate through the nitric oxide synthase/NO system. However, the potential neurotoxicity of NO introduces an element of controversy regarding its therapeutic utility in AD. This review focuses on research findings concerning NO's role in experimental AD and its underlying mechanisms. Furthermore, we have proposed directions for future research based on our current comprehension of this critical area.

The blood-brain barrier and the neurovascular unit in subarachnoid hemorrhage: molecular events and potential treatments

The response of the blood-brain barrier (BBB) following a stroke, including subarachnoid hemorrhage (SAH), has been studied extensively. The main components of this reaction are endothelial cells, pericytes, and astrocytes that affect microglia, neurons, and vascular smooth muscle cells. SAH induces alterations in individual BBB cells, leading to brain homeostasis disruption. Recent experiments have uncovered many pathophysiological cascades affecting the BBB following SAH. Targeting some of these pathways is important for restoring brain function following SAH. BBB injury occurs immediately after SAH and has long-lasting consequences, but most changes in the pathophysiological cascades occur in the first few days following SAH. These changes determine the development of early brain injury as well as delayed cerebral ischemia. SAH-induced neuroprotection also plays an important role and weakens the negative impact of SAH. Supporting some of these beneficial cascades while attenuating the major pathophysiological pathways might be decisive in inhibiting the negative impact of bleeding in the subarachnoid space. In this review, we attempt a comprehensive overview of the current knowledge on the molecular and cellular changes in the BBB following SAH and their possible modulation by various drugs and substances.

Immune Modulatory Effects of Nonsteroidal Anti-inflammatory Drugs in the Perioperative Period and Their Consequence on Postoperative Outcome

Nonsteroidal anti-inflammatory drugs are among the most commonly administered drugs in the perioperative period due to their prominent role in pain management. However, they potentially have perioperative consequences due to immune-modulating effects through the inhibition of prostanoid synthesis, thereby affecting the levels of various cytokines. These effects may have a direct impact on the postoperative outcome of patients since the immune system aims to restore homeostasis and plays an indispensable role in regeneration and repair. By affecting the immune response, consequences can be expected on various organ systems. This narrative review aims to highlight these potential immune system-related consequences, which include systemic inflammatory response syndrome, acute respiratory distress syndrome, immediate and persistent postoperative pain, effects on oncological and neurologic outcome, and wound, anastomotic, and bone healing.

Emerging therapeutic targets for cerebral edema

INTRODUCTION

Cerebral edema is a key contributor to death and disability in several forms of brain injury. Current treatment options are limited, reactive, and associated with significant morbidity. Targeted therapies are emerging based on a growing understanding of the molecular underpinnings of cerebral edema.

AREAS COVERED

We review the pathophysiology and relationships between different cerebral edema subtypes to provide a foundation for emerging therapies. Mechanisms for promising molecular targets are discussed, with an emphasis on those advancing in clinical trials, including ion and water channels (AQP4, SUR1-TRPM4) and other proteins/lipids involved in edema signaling pathways (AVP, COX2, VEGF, and S1P). Research on novel treatment modalities for cerebral edema [including recombinant proteins and gene therapies] is presented and finally, insights on reducing secondary injury and improving clinical outcome are offered.

EXPERT OPINION

Targeted molecular strategies to minimize or prevent cerebral edema are promising. Inhibition of SUR1-TRPM4 (glyburide/glibenclamide) and VEGF (bevacizumab) are currently closest to translation based on advances in clinical trials. However, the latter, tested in glioblastoma multiforme, has not demonstrated survival benefit. Research on recombinant proteins and gene therapies for cerebral edema is in its infancy, but early results are encouraging. These newer modalities may facilitate our understanding of the pathobiology underlying cerebral edema.

Gene expression profiling of brain endothelial cells after experimental subarachnoid haemorrhage

Subarachnoid haemorrhage (SAH) is a type of hemorrhagic stroke that is associated with high morbidity and mortality. New effective treatments are needed to improve outcomes. The pathophysiology of SAH is complex and includes early brain injury and delayed cerebral ischemia, both of which are characterized by blood–brain barrier (BBB) impairment. We isolated brain endothelial cells (BECs) from mice subjected to SAH by injection of blood into the prechiasmatic cistern. We used gene expression profiling to identify 707 unique genes (2.8% of transcripts, 403 upregulated, 304 downregulated, 24,865 interrogated probe sets) that were significantly differentially expressed in mouse BECs after SAH. The pathway involving prostaglandin synthesis and regulation was significantly upregulated after SAH, including increased expression of the Ptgs2 gene and its corresponding COX-2 protein. Celecoxib, a selective COX-2 inhibitor, limited upregulation of Ptgs2 in BECs. In this study, we have defined the gene expression profiling of BECs after experimental SAH and provide further insight into BBB pathophysiology, which may be relevant to other neurological diseases such as traumatic brain injury, brain tumours, ischaemic stroke, multiple sclerosis, and neurodegenerative disorders.

Review of aromatherapy essential oils and their mechanism of action against migraines

ETHNOPHARMACOLOGICAL RELEVANCE

Migraines have become a major threat to human health, as they significantly affect human health and quality of life due to a high prevalence rate, attack rate and pain intensity. Aromatherapy, with its comfortable and pleasant natural characteristics and rapid and efficient characteristics, is widely favored by patients in the folk. Chinese folk also have the application history and related records of aromatic plants in the treatment of migraine.

AIM OF THE STUDY

This study was conducted to review the pathogenesis of migraine, the application of plant essential oils in the treatment of migraine, and further explore the material basis and mechanism of action of plant essential oils against migraine.

MATERIALS AND METHODS

Search the electronic literature of essential oils with anti-migraine effect in Google Scholar, PubMed and China National Knowledge Infrastructure, and further search the research situation of the monomer components of essential oils in migraine, inflammation, pain and other aspects.

RESULTS

studies show that there are 10 types of plant essential oils that could relieve migraine symptoms, and that 16 monomers may play a role in migraine treatment by effectively inhibiting neurogenic inflammation, hyperalgesia and balancing vasorelaxation.

CONCLUSION

Aromatic plant essential oils can relieve migraine effectively, these findings can be used as an important part of the development of anti-migraine drugs.

Interleukin-6: Important Mediator of Vasospasm Following Subarachnoid Hemorrhage

The correlation of neuroinflammation with the development of cerebral vasospasm following subarachnoid hemorrhage has been well documented in the literature; both clinical and preclinical. The exact mechanisms by which this process occurs, however, are poorly elucidated. Recent evidence indicates that interleukin-6 is not only an important prognostic biomarker for subarachnoid hemorrhage and subsequent vasospasm development but also an integral component in the progression of injury following initial insult. In this review, we briefly highlight other pathways under investigation and focus heavily on what has been discovered regarding the role of interleukin 6 and cerebral vasospasm following subarachnoid hemorrhage. A proposed mechanistic pathway is highlighted in written and graphical format. A discussion regarding the human correlative findings and initial pre-clinical mechanistic studies is addressed. Finally, in the future investigation section, innovative developments and a clear description of areas warranting further scientific inquiry are emphasized. This review will catalyze continued discovery in this area of emerging significance and aid in the quest for effective vasospasm treatment where limited clinical therapeutics currently exist.

The role of immune inflammation in aneurysmal subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) is a devastating disease, which mainly caused by the rupture of an intracranial aneurysm. Clinical trials have demonstrated that cerebral vasospasm (CVS) is not the sole contributor to delayed cerebral ischemia (DCI) and poor outcomes in patients with aSAH. Currently, accumulating evidence suggests that early brain injury (EBI), which occurs within 72 h after the onset of aSAH, lays the foundation for subsequent pathophysiological changes and poor outcomes of patients. The pathological mechanisms of EBI mainly include increased intracranial pressure, oxidative stress, neuroinflammation, blood-brain barrier (BBB) disruption, cerebral edema and cell death. Among them, the brain immune inflammatory responses involve a variety of immune cells and active substances, which play an important role in EBI after aSAH and may be related to DCI and long-term outcomes. Thus, attention should be paid to strategies targeting cerebral immune inflammatory responses. In this review, we discuss the role of immune inflammatory responses in the occurrence and development of aSAH, as well as some inflammatory biomarkers related to CVS, DCI, and aSAH outcomes. In addition, we also summarize the potential therapeutic drugs that target cerebral immune inflammatory responses for patients with aSAH in current research.

Non-steroidal anti-inflammatory drugs in the pathophysiology of vasospasms and delayed cerebral ischemia following subarachnoid hemorrhage: a critical review

Aneurysmal subarachnoid hemorrhage (aSAH) is a life-threatening condition associated with the development of early brain injury (EBI) and delayed cerebral ischemia (DCI). Pharmacological treatment of vasospasm following aSAH currently mainly comprises nimodipine administration. In the past few years, many drugs that can potentially benefit cases of subarachnoid hemorrhage have become available. The objective of this review is to critically assess the effects of non-steroidal anti-inflammatory drugs (NSAIDs) following aSAH. A systematic literature review was conducted following PRISMA guidelines. The search was aimed at studies addressing aSAH and NSAIDs during the 2010 to 2019 period, and it yielded 13 articles. Following the application of search criteria, they were divided into two groups, one containing 6 clinical articles and the other containing 7 experimental articles on animal models of aSAH. Inflammatory cerebral changes after aneurysm rupture contribute to the development of EBI, DCI and cerebral vasospasm. It appears that NSAIDs (especially coxibs) are even more effective in reducing vasospasm than nimodipine. Other beneficial effects of NSAIDs include reduction in mortality, improved functional outcome and increased hypoaggregability. However, despite these positive effects, there is only one randomized, double-blind, placebo-controlled trial showing a tendency towards a better outcome with lower incidence of vasospasm or mortality in patients following aSAH.

Elucidating the novel biomarker and therapeutic potentials of High-mobility group box 1 in Subarachnoid hemorrhage: A review

Subarachnoid hemorrhage (SAH) frequently arises after an aneurysm in a cerebral artery ruptures, resulting into bleeding as well as clot formation. High-mobility group box 1 (HMGB1) is an extremely preserved, universal protein secreted in the nuclei of all cell varieties. This review explores the biomarker as well as therapeutic potentials of HMBG1 in SAH especially during the occurrence of cerebral vasospasms. Plasma HMGB1 levels have proven to be very useful prognosticators of effective outcome as well as death after SAH. Correspondingly, higher HMGB1 levels in the cerebrospinal fluid (CSF) of SAH patients correlated well with poor outcome; signifying that, CSF level of HMGB1 is a novel predictor of outcome following SAH. Nonetheless, the degree of angiographic vasospasm does not always correlate with the degree of neurological deficits in SAH patients. HMGB1 stimulated cerebral vasospasm, augmented gene as well as protein secretory levels of receptor for advance glycation end product (RAGE) in neurons following SAH; which means that, silencing HMGB1 during SAH could be of therapeutic value. Compounds like resveratrol, glycyrrhizin, rhinacanthin, purpurogallin, 4′-O-β-D-Glucosyl-5-O-Methylvisamminol (4OGOMV) as well as receptor-interacting serine/threonine-protein kinase 3 (RIPK3) gene are capable of interacting with HMGB1 resulting in therapeutic benefits following SAH.

Intrathecal Fibrinolysis for Aneurysmal Subarachnoid Hemorrhage: Evidence From Randomized Controlled Trials and Cohort Studies

Background: The role of intrathecal fibrinolysis for the treatment of patients with aneurysmal subarachnoid hemorrhage (aSAH) has been widely investigated; however, the results have been contradictory. In our study, we conducted a meta-analysis to evaluate the safety and efficacy of intrathecal (intracisternal or intraventricular) fibrinolysis for aSAH.

Methods: PubMed, Web of Science, Embase, Medline, and the Cochrane library databases were searched up to February 1, 2019. The outcomes analyzed were neurologic recovery, delayed ischemic neurologic deficit (DIND), mortality, and the incidence of chronic hydrocephalus and hemorrhage.

Results: A total of 21 studies comprising 1,373 patients were analyzed, including nine randomized controlled trials (RCTs) and 12 non-RCTs. The results showed that intracisternal fibrinolysis significantly decreased poor neurologic outcomes (RR = 0.62, 95% CI = 0.50–0.76, P < 0.001) and reduced the incidence of DIND (RR = 0.52, 95% CI = 0.41–0.65, P <0.001), chronic hydrocephalus (RR = 0.59, 95% CI = 0.42–0.82, P = 0.002) and mortality (RR = 0.58, 95% CI = 0.37, 0.93, P = 0.02). There was no significant difference in the occurrence of hemorrhage. Moreover, the results of the Egger test and Begg's funnel plot showed no evidence of publication bias.

Conclusions: Current evidence suggests that intracisternal fibrinolysis has beneficial effects on the clinical outcomes of patients with aSAH. However, further well-designed randomized trials are needed to confirm the efficacy and safety of intracisternal fibrinolysis for the treatment of aSAH.

The dual-functional memantine nitrate MN-08 alleviates cerebral vasospasm and brain injury in experimental subarachnoid haemorrhage models

BACKGROUND AND PURPOSE

Cerebral vasospasm and neuronal apoptosis after subarachnoid haemorrhage (SAH) is the major cause of morbidity and mortality in SAH patients. So far, single-target agents have not prevented its occurrence. Memantine, a non-competitive NMDA re3ceptor antagonist, is known to alleviate brain injury and vasospasm in experimental models of SAH. Impairment of NO availability also contributes to vasospasm. Recently, we designed and synthesized a memantine nitrate MN-08, which has potent dual functions: neuroprotection and vasodilation. Here, we have tested the therapeutic effects of MN-08 in animal models of SAH.

EXPERIMENTAL APPROACH

Binding to NMDA receptors (expressed in HEK293 cells), NO release and vasodilator effects of MN-08 were assessed in vitro. Therapeutic effects of MN-08 were investigated in vivo, using rat and rabbit SAH models.

KEY RESULTS

MN-08 bound to the NMDA receptor, slowly releasing NO in vitro and in vivo. Consequently, MN-08 relaxed the pre-contracted middle cerebral artery ex vivo and increased blood flow velocity in small vessels of the mouse cerebral cortex. It did not, however, lower systemic blood pressure. In an endovascular perforation rat model of SAH, MN-08 improved the neurological scores and ameliorated cerebral vasospasm. Moreover, MN-08 also alleviated cerebral vasospasm in a cisterna magna single-injection model in rabbits. MN-08 attenuated neural cell apoptosis in both rat and rabbit models of SAH. Importantly, the therapeutic benefit of MN-08 was greater than that of memantine.

CONCLUSION AND IMPLICATIONS

MN-08 has neuroprotective potential and can ameliorate vasospasm in experimental SAH models.

PDGFR-β modulates vascular smooth muscle cell phenotype via IRF-9/SIRT-1/NF-κB pathway in subarachnoid hemorrhage rats

Platelet-derived growth factor receptor-β (PDGFR-β) has been reported to promote phenotypic transformation of vascular smooth muscle cells (VSMCs). The purpose of this study was to investigate the role of the PDGFR-β/IRF9/SIRT-1/NF-κB pathway in VSMC phenotypic transformation after subarachnoid hemorrhage (SAH). SAH was induced using the endovascular perforation model in Sprague-Dawley rats. PDGFR-β small interfering RNA (siRNA) and IRF9 siRNA were injected intracerebroventricularly 48 h before SAH. SIRT1 activator (resveratrol) and inhibitor (EX527) were administered intraperitoneally 1 h after SAH induction. Twenty-four hours after SAH, the VSMC contractile phenotype marker α-smooth muscle actin (α-SMA) decreased, whereas the VSMC synthetic phenotype marker embryonic smooth muscle myosin heavy chain (Smemb) increased. Both PDGFR-β siRNA and IRF9 siRNA attenuated the induction of nuclear factor-κB (NF-κB) and enhanced the expression of α-SMA. The SIRT1 activator (resveratrol) preserved VSMC contractile phenotype, significantly alleviated neurological dysfunction, and reduced brain edema. However, these beneficial effects of PDGFR-β siRNA, IRF9 siRNA and resveratrol were abolished by the SIRT1 inhibitor (EX527). This study shows that PDGFR-β/IRF9/SIRT-1/NF-κB signaling played a role in the VSMC phenotypic transformation after SAH. Inhibition of this signaling cascade preserved the contractile phenotype of VSMCs, thereby improving neurological outcomes following SAH.

The Role of Oxidative Stress in Microvascular Disturbances after Experimental Subarachnoid Hemorrhage

Oxidative stress was shown to play a crucial role in the diverse pathogenesis of early brain injury (EBI) after subarachnoid hemorrhage (SAH). Microcirculatory dysfunction is thought to be an important and fundamental pathological change in EBI. However, other than blood-brain barrier (BBB) disruption, the influence of oxidative stress on microvessels remains to be elucidated. The aim of this study was to investigate the role of oxidative stress on microcirculatory integrity in EBI. SAH was induced in male Sprague-Dawley rats using an endovascular perforation technique. A free radical scavenger, edaravone, was administered prophylactically by intraperitoneal injection. SAH grade, neurological score, brain water content, and BBB permeability were measured at 24 h after SAH induction. In addition, cortical samples taken at 24 h after SAH were analyzed to explore oxidative stress, microvascular mural cell apoptosis, microspasm, and microthrombosis. Edaravone treatment significantly ameliorated neurological deficits, brain edema, and BBB disruption. In addition, oxidative stress-induced modifications and subsequent apoptosis of microvascular endothelial cells and pericytes increased after SAH induction, while the administration of edaravone suppressed this. Consistent with apoptotic cell inhibition, microthromboses were also inhibited by edaravone administration. Oxidative stress plays a pivotal role in the induction of multiple pathological changes in microvessels in EBI. Antioxidants are potential candidates for the treatment of microvascular disturbances after SAH.

Salvinorin A ameliorates cerebral vasospasm through activation of endothelial nitric oxide synthase in a rat model of subarachnoid hemorrhage

OBJECTIVE

This study aimed to demonstrate the potential of salvinorin A (SA) for cerebral vasospasm after subarachnoid hemorrhage (SAH) and investigate mechanisms of therapeutic effect using rat SAH model.

METHODS

Salvinorin A was injected intraperitoneally, and the neurobehavioral changes were observed at 12 hours, 24 hours, 48 hours, and 72 hours after SAH. Basilar artery was observed by magnetic resonance imaging (MRI). The inner diameter and thickness of basilar artery were measured. The morphological changes and the apoptosis in CA1 area of hippocampus were detected. Endothelin-1 (ET-1) and nitric oxide (NO) levels were detected by ELISA kit. The protein expression of endothelial NO synthase (eNOS) and aquaporin-4 (AQP-4) was determined by Western blot for potential mechanism exploration.

RESULTS

Salvinorin A administration could relieve neurological deficits, decrease the neuronal apoptosis, and alleviate the morphological changes in CA1 area of hippocampus. SA alleviated CVS by increasing diameter and decreasing thickness of basilar artery, and such changes were accompanied by the decreased concentration of ET-1 and increased level of NO. Meanwhile, SA increased the expression of eNOS and decreased the expression of AQP-4 protein in the basilar artery and hippocampus.

CONCLUSIONS

Salvinorin A attenuated CVS and alleviated brain injury after SAH via increasing expression of eNOS and NO content, and decreasing ET-1 concentration and AQP-4 protein expression.

Anti-inflammation conferred by stimulation of CD200R1 via Dok1 pathway in rat microglia after germinal matrix hemorrhage

CD200 has been reported to be neuroprotective in neurodegenerative diseases. However, the potential protective effects of CD200 in germinal matrix hemorrhage (GMH) have not been investigated. We examined the anti-inflammatory mechanisms of CD200 after GMH. A total of 167 seven-day-old rat pups were used. The time-dependent effect of GMH on the levels of CD200 and CD200 Receptor 1 (CD200R1) was evaluated by western blot. CD200R1 was localized by immunohistochemistry. The short-term (24 h) and long-term (28 days) outcomes were evaluated after CD200 fusion protein (CD200Fc) treatment by neurobehavioral assessment. CD200 small interfering RNA (siRNA) and downstream of tyrosine kinase 1 (Dok1) siRNA were injected intracerebroventricularly. Western blot was employed to study the mechanisms of CD200 and CD200R1. GMH induced significant developmental delay and caused impairment in both cognitive and motor functions in rat pups. CD200Fc ameliorated GMH-induced damage. CD200Fc increased expression of Dok1 and decreased IL-1beta and TNF-alpha levels. CD200R1 siRNA and Dok1 siRNA abolished the beneficial effects of CD200Fc, as demonstrated by enhanced expression levels of IL-1beta and TNF-alpha. CD200Fc inhibited GMH-induced inflammation and this effect may be mediated by CD200R1/Dok1 pathway. Thus, CD200Fc may serve as a potential treatment to ameliorate brain injury for GMH patients.

The Role of Autophagy in Subarachnoid Hemorrhage: An Update

BACKGROUND

Autophagy is an extensive self-degradation process for the disposition of cytosolic aggregated or misfolded proteins and defective organelles which executes the functions of pro-survival and pro-death to maintain cellular homeostasis. The pathway plays essential roles in several neurological disorders. Subarachnoid Hemorrhage (SAH) is a devastating subtype of hemorrhagic stroke with high risk of neurological deficit and high mortality. Early brain injury (EBI) plays a role in the poor clinical course and outcome after SAH. Recent studies have paid attention on the role of the autophagy pathway in the development of EBI after SAH. We aim to update the multifaceted roles of autophagy pathway in the pathogenesis of SAH, especially in the phase of EBI.

METHODS

We reviewed early researches related to autophagy and SAH. The following three aspects of contents will be mainly discussed: the process of the autophagy pathway, the role of the autophagy in SAH and the interaction between organelle dysfunction and autophagy pathway after SAH.

RESULTS

Accumulating evidence shows an increased autophagy reaction in response to early stages of SAH. However, others suggest inadequate or excessive autophagy activation can result in cell injury and death. In addition to autophagy, apoptosis and necrosis can occur in neurons simultaneously after SAH, leading to mixed features of cell death morphologies. And it is also known that there is extensive crosstalk between autophagy and apoptosis pathway. Subcellular organelles of neural cells generally participate in the formation and functional parts of autophagy process.

CONCLUSION

Autophagy plays an important role in the SAH-induced brain injury. A better understanding of the interrelationship among autophagy, apoptosis, and necrosis might provide us better therapeutic targets for the treatment of SAH.

Transcranial Near-infrared Laser Therapy in Improving Cognitive Recovery of Function Following Traumatic Brain Injury

Abstract: Traumatic brain injury (TBI) has turned into a major health and socioeconomic problem affecting young people and military personnel. Numerous TBI patients experienced the sequela of brain injury called cognitive impairment, which re-duced functions in attention, working memory, motivation, and execution. In recent years, transcranial near-infrared laser therapy (tNiRLT) as a possible therapy has been gradually applied in treating cognitive impairment post-TBI. In the present review, the biological mechanisms of transcranial tNiRLT for TBI are synthesized mainly based on the photonic impact of chronic mild TBI. Various exciting molecular events possibly occur during the procedure, such as stimulation of ATP pro-duction, regional cerebral blood flow, acupoint, neurogenesis and synaptogenesis, as well as a reduction in anti-inflammatory effect. Some animal experiments and clinical studies of tNiRLT for TBI are outlined. Several labs have displayed that tNiRLT is effective not only in improving neurological functions but also in increasing memory and learning capacity in ro-dent animals’ model of TBI. In a 2 patients case report and a 11-case series, cognitive functions were ameliorated. Efficacy on cognitive and emotional effects was also observed in a double-blind, controlled clinical study. Several Randomized, paral-lel, double blind, sham-controlled trials are underway, aiming to evaluate the efficacy of tLED on cognitive functions and neuropsychiatric status in participants post-TBI. Therefore, tNiRLT is a promising method applied to cognitive impairment following TBI.

Regulation of Hypertension for Secondary Prevention of Stroke: The Possible 'Bridging Function' of Acupuncture

Worldwide, stroke is the leading cause of mortality and disability, with hypertension being an independent risk factor for a secondary stroke. Acupuncture for the treatment of hypertension gains more attention in alternative and complementary medicine, but the results are inconsistent. Few studies regarding the secondary prevention of stroke by managing hypertension with acupuncture have been carried out as there are some problems regarding the antihypertensive drug status in the secondary prevention of stroke. Still, the potential of acupuncture in regulating the blood pressure for secondary stroke prevention deserves our focus. This review is based on papers recorded in the PubMed, Embase, and Web of Science databases, from their inception until March 28, 2017, and retrieved with the following search terms: hypertension and acupuncture, limited in spontaneously hypertensive rats (SHRs), stress-induced (or cold-induced) hypertensive or pre-hypertensive models. We find that, in these hypertensive animals, acupuncture could mainly influence factors related to the nervous system, oxidative stress, the endocrine system, cardiovascular function, and hemorheology, which are closely associated with the stroke outcome. This trend may give us a hint that acupuncture might well participate in the secondary prevention of stroke through these pathways when used in the management of hypertension.

In vivo observation of cerebral microcirculation after experimental subarachnoid hemorrhage in mice

Acute brain injury caused by subarachnoid hemorrhage is the major cause of poor prognosis. The pathology of subarachnoid hemorrhage likely involves major morphological changes in the microcirculation. However, previous studies primarily used fixed tissue or delayed injury models. Therefore, in the present study, we used in vivo imaging to observe the dynamic changes in cerebral microcirculation after subarachnoid hemorrhage. Subarachnoid hemorrhage was induced by perforation of the bifurcation of the middle cerebral and anterior cerebral arteries in male C57/BL6 mice. The diameter of pial arterioles and venules was measured by in vivo fluorescence microscopy at different time points within 180 minutes after subarachnoid hemorrhage. Cerebral blood flow was examined and leukocyte adhesion/albumin extravasation was determined at different time points before and after subarachnoid hemorrhage. Cerebral pial microcirculation was abnormal and cerebral blood flow was reduced after subarachnoid hemorrhage. Acute vasoconstriction occurred predominantly in the arterioles instead of the venules. A progressive increase in the number of adherent leukocytes in venules and substantial albumin extravasation were observed between 10 and 180 minutes after subarachnoid hemorrhage. These results show that major changes in microcirculation occur in the early stage of subarachnoid hemorrhage. Our findings may promote the development of novel therapeutic strategies for the early treatment of subarachnoid hemorrhage.

CpG-ODN exerts a neuroprotective effect via the TLR9/pAMPK signaling pathway by activation of autophagy in a neonatal HIE rat model

Hypoxic Ischemic Encephalopathy (HIE) is an injury caused to the brain due to prolonged lack of oxygen and blood supply which results in death or long-term disabilities. The main aim of this study was to investigate the role of Cytosine-phospho-guanine oligodeoxynucleotide (CpG-ODN) in autophagy after HIE. Ten-day old (P10) rat pups underwent right common carotid artery ligation followed by 2.5h of hypoxia as previously described by Rice-Vannucci. At 1h post HIE, rats were intranasally administered with recombinant CpG-ODN. Time-course expression levels of endogenous key proteins, TLR9, pAMPK/AMPK, LC3II/I, and LAMP1 involved in CpG-ODN's protective effects were measured using western blot. Short (48h) and long (4w) term neurobehavior studies were performed using righting reflex, negative geotaxis, water maze, foot fault and Rota rod tests. Brain samples were collected after long term for histological analysis. Furthermore, to elucidate the pathway via which CpG-ODN confers protection, TLR9 and AMPK inhibitors were used. Time course results showed that the expression of TLR9, pAMPK/AMPK, LC3II/I, LAMP1 increased after HIE. Neurobehavioral studies showed that HIE induced a significant delay in development and resulted in cognitive and motor function deficits. However, CpG-ODN ameliorated HIE-induced outcomes and improved long term neurological deficits. In addition, CpG-ODN increased expression of pAMPK/AMPK, p-ULK1/ULK1, P-AMBRA1/AMBRA1, LC3II/I and LAMP1 while inhibition of TLR9 and AMPK reversed those effects. In summary, CpG-ODN increased HIE-induced autophagy and improved short and long term neurobehavioral outcomes which may be mediated by the TLR9/pAMPK signaling pathway after HIE.

The Role of Thromboinflammation in Delayed Cerebral Ischemia after Subarachnoid Hemorrhage

Delayed cerebral ischemia (DCI) is a major determinant of patient outcome following aneurysmal subarachnoid hemorrhage. Although the exact mechanisms leading to DCI are not fully known, inflammation, cerebral vasospasm, and microthrombi may all function together to mediate the onset of DCI. Indeed, inflammation is tightly linked with activation of coagulation and microthrombi formation. Thromboinflammation is the intersection at which inflammation and thrombosis regulate one another in a feedforward manner, potentiating the formation of thrombi and pro-inflammatory signaling. In this review, we will explore the role(s) of inflammation and microthrombi in subarachnoid hemorrhage (SAH) pathophysiology and DCI, and discuss the potential of targeting thromboinflammation to prevent DCI after SAH.

The role of nitric oxide in stroke

Stroke is considered to be an acute cerebrovascular disease, including ischemic stroke and hemorrhagic stroke. The high incidence and poor prognosis of stroke suggest that it is a highly disabling and highly lethal disease which can pose a serious threat to human health. Nitric oxide (NO), a common gas in nature, which is often thought as a toxic gas, because of its intimate relationship with the pathological processes of many diseases, especially in the regulation of blood flow and cell inflammation. However, recent years have witnessed an increased interest that NO plays a significant and positive role in stroke as an essential gas signal molecule. In view of the fact that the neuroprotective effect of NO is closely related to its concentration, cell type and time, only in the appropriate circumstances can NO play a protective effect. The purpose of this review is to summarize the roles of NO in ischemic stroke and hemorrhagic stroke.

Anti-high mobility group box-1 (HMGB1) antibody attenuates delayed cerebral vasospasm and brain injury after subarachnoid hemorrhage in rats

Although delayed cerebral vasospasm (DCV) following subarachnoid hemorrhage (SAH) is closely related to the progression of brain damage, little is known about the molecular mechanism underlying its development. High mobility group box-1 (HMGB1) plays an important role as an initial inflammatory mediator in SAH. In this study, an SAH rat model was employed to evaluate the effects of anti-HMGB1 monoclonal antibody (mAb) on DCV after SAH. A vasoconstriction of the basilar artery (BA) associated with a reduction of nuclear HMGB1 and its translocation in vascular smooth muscle cells were observed in SAH rats, and anti-HMGB1 mAb administration significantly suppressed these effects. Up-regulations of inflammation-related molecules and vasoconstriction-mediating receptors in the BA of SAH rats were inhibited by anti-HMGB1 mAb treatment. Anti-HMGB1 mAb attenuated the enhanced vasocontractile response to thrombin of the isolated BA from SAH rats and prevented activation of cerebrocortical microglia. Moreover, locomotor activity and weight loss recovery were also enhanced by anti-HMGB1 mAb administration. The vasocontractile response of the BA under SAH may be induced by events that are downstream of responses to HMGB1-induced inflammation and inhibited by anti-HMGB1 mAb. Anti-HMGB1 mAb treatment may provide a novel therapeutic strategy for DCV and early brain injury after SAH.

Effects of Toll-Like Receptor 4 Antagonists Against Cerebral Vasospasm After Experimental Subarachnoid Hemorrhage in Mice

Toll-like receptor 4 (TLR4) signaling may play a crucial role in the occurrence of cerebral vasospasm after subarachnoid hemorrhage (SAH). The main purpose of this study was to assess if selective blockage of TLR4 on cerebral arteries prevents cerebral vasospasm development and neurological impairments after SAH in mice. One hundred fourteen mice underwent endovascular perforation SAH or sham operation and were randomly divided into the following 6 groups: sham+vehicle, sham+LPS-RS ultrapure 8 μg, sham+LPS-RS ultrapure 40 μg, SAH+vehicle, SAH+LPS-RS ultrapure 8 μg, and SAH+LPS-RS ultrapure 40 μg. A selective TLR4 antagonist, LPS-RS ultrapure (8 or 40 μg), was administered intracerebroventricularly to mice at 30 min, and the effects were evaluated by neurobehavioral tests and India-ink angiography at 24-48 h, and Western blotting and immunohistochemistry on cerebral arteries at 24 h post-SAH. Higher but not lower dosages of LPS-RS ultrapure significantly prevented post-SAH neurological impairments and ameliorated cerebral vasospasm. SAH caused TLR4 activation and cyclooxygenase-1 (COX1) upregulation in the endothelial cells and smooth muscle cells of spastic cerebral arteries, both of which were significantly suppressed by LPS-RS ultrapure. Another selective TLR4 antagonist, IAXO-102, which has a different binding site from LPS-RS ultrapure, also showed similar protective effects to LPS-RS ultrapure. These findings suggest that TLR4 signaling is implicated in cerebral vasospasm development at least partly via COX1 upregulation, and that TLR4 antagonists have therapeutic potential as a new therapy against cerebral vasospasm.