Vagus nerve stimulation as immunomodulatory therapy for stroke: A comprehensive review.

Stroke is a devastating cerebrovascular pathology with high morbidity and mortality. Inflammation plays a central role in the pathophysiology of stroke. Vagus nerve stimulation (VNS) is a promising immunomodulatory method that has shown positive effects in stroke treatment, including neuroprotection, anti-apoptosis, anti-inflammation, antioxidation, reduced infarct volume, improved neurological scores, and promotion of M2 microglial polarization. In this review, we summarize the current knowledge about the vagus nerve's immunomodulatory effects through the cholinergic anti-inflammatory pathway (CAP) and provide a comprehensive assessment of the available experimental literature focusing on the use of VNS in stroke treatment.

Immune system disorders in the early post-injury period in patients after severe brain injury from the perspective of the severity of the injury.

BACKGROUND: Brain injuries are the most common cause of death in productive age. Besides the extent of the injury, other systemic factors can also affect the outcome. Patients suffering from severe brain injury often experience extracranial inflammatory complications during the early period of treatment. Here, we investigate the changes in immunity in patients with brain injury. METHODS: 121 patients and 92 healthy controls were included in the research. Blood samples were collected on admission and analyzed by flow cytometry and biochemical methods. Multiple clusters of differentiation (CD) and antibody levels were investigated. The results were compared between patients and controls. In addition, results of two classes of severity (Glasgow Coma Scale, GCS, of 3-5 vs. 6-8) were also compared. RESULTS: Parameters of humoral immunity in patients immediately after admission were significantly lower than those from healthy donors, with the exception of IgE elevated as much as to resemble allergic reaction (p < 0.01). Of cellular parameters, only natural killer (NK) cluster CD56 + was elevated (p < 0.01). Extracranial infectious complications were more common in patients with GCS 3-5. CONCLUSIONS: Strong immune system disorders were observed in patients after severe brain injury, which may contribute to the worse outcome in such patients.

Oxidative Stress in the Brain: Basic Concepts and Treatment Strategies in Stroke.

The production of free radicals is inevitably associated with metabolism and other enzymatic processes. Under physiological conditions, however, free radicals are effectively eliminated by numerous antioxidant mechanisms. Oxidative stress occurs due to an imbalance between the production and elimination of free radicals under pathological conditions. Oxidative stress is also associated with ageing. The brain is prone to oxidative damage because of its high metabolic activity and high vulnerability to ischemic damage. Oxidative stress, thus, plays a major role in the pathophysiology of both acute and chronic pathologies in the brain, such as stroke, traumatic brain injury or neurodegenerative diseases. The goal of this article is to summarize the basic concepts of oxidative stress and its significance in brain pathologies, as well as to discuss treatment strategies for dealing with oxidative stress in stroke.

The efficacy of surgical treatment of cerebral arteriovenous malformations in a single academic institution: a case series.

AIM: To report on patients who underwent surgical treatment of arteriovenous malformations (AVMs) at our institution. METHODS: This retrospective single-center case series enrolled the patients who underwent surgical treatment of pial AVM at the Department of Neurosurgery, University Hospital Brno, between 2005 and 2019. The data are summarized as descriptive statistics presenting basic characteristics in all the patients and in sex or age subgroups. RESULTS: Fifty patients were enrolled. The majority of AVMs were of Spetzler-Martin grade II (n=27; 54%), localized supratentorialy (n=43; 86%), and half of AVMs were ruptured. A total resection was performed in 48 patients (96%), and a good overall outcome was achieved in 44 patients (88%). Surgery-associated morbidity was 2%, and the mortality rate was 0% due to meticulous selection of patients for surgical treatment. CONCLUSION: Microsurgery is an appropriate method of treatment for S-M grade I-III pial AVMs. Microsurgery may be used to treat the majority of small-nidus AVMs with a low mortality and morbidity, when precisely planned and performed by an expert vascular team. The meticulous selection of patients for surgical treatment is crucial.

Current Treatment of Anterior Communicating Artery Aneurysms: Single Center Study.

INTRODUCTION: Anterior communicating artery aneurysms (ACoAAs) are the most frequent intracranial aneurysms treated at neurosurgical departments with a vascular program. MATERIAL AND METHODS: We reviewed patients with ACoAAs in a single institution over ten years (2008-2017). The focus was on the final outcome; complications, age, and clinical condition with respect to modalities were analyzed. RESULTS: A total of 198 patients treated during this period was included in the study: 176 patients had a ruptured ACoAA and 22 had an unruptured ACoAA. Then, 127 (71%) were treated surgically and 51 (29%) by endovascular means. Out of the whole series, a good recovery occurred in 123 patients (62%), moderate disability in 11 (5.5%), severe disability in 19 (10%), vegetative state in 11 (5.5%), and death in 34 (17%). In the 157 patients (72.5%) with a subarachnoid hemorrhage (SAH), both modalities had a favorable outcome: 27.5% had an unfavorable outcome, 12% had complications in surgery versus 17.6% during endovascular treatment. No statistical difference in outcome, complications, and age was noted between modalities. Surgical treatment was more frequently adopted for patients in a better clinical condition (p ≤ 0.05). CONCLUSION: More than two thirds of the patients (72.5%) reached a favorable outcome. There was no difference in age between the treatment modalities. Risks of complications are present and specific for both modalities.

Early Dynamics of Interleukin-6 in Cerebrospinal Fluid after Aneurysmal Subarachnoid Hemorrhage.

BACKGROUND: Subarachnoid hemorrhage (SAH) is a severe condition associated with high mortality. Early brain injury (EBI) plays an important role in the pathophysiology of SAH, and inflammation is a major contributor to EBI. Inflammation is a widely studied topic in both experimental and clinical conditions; however, just a few clinical studies have focused primarily on the early inflammatory response after SAH, and detailed information about the association between the dynamics of early inflammatory response with main clinical characteristics is lacking. This study analyzes the early dynamics of inflammatory response after SAH and evaluates the possible associations between the markers of early inflammatory response and main clinical characteristics. PATIENTS AND METHODS: A total of 47 patients with a diagnosis of aneurysmal SAH within the last 24 hours were enrolled in the study. All treatments, including treatment of aneurysm (surgery/coiling) and implantation of a drainage system (external ventricular drainage/lumbar catheter), were conducted in the same way as in other patients with this diagnosis. Blood and cerebrospinal fluid (CSF) samples were collected three times a day for 4 days. The dynamics of proinflammatory cytokines were assessed, and associations between levels of the proinflammatory cytokines interleukin (IL)-6, IL-1ß, or tumor necrosis factor (TNF)α and main clinical characteristics were evaluated using linear mixed-effect models. RESULTS: The CSF levels of IL-6 were massively increased initially after SAH (up to 72 hours) with an additional increase in later phases (after 72 hours), but there was high variability in IL-6 levels. A significant association was noted between the Glasgow Outcome Scale score and both overall levels of IL-6 (p = 0.0095) and their dynamics (p = 0.0208); the effect of the Hunt and Hess scale was borderline (p = 0.0887). No association was found between IL-6 levels and Fisher grade, modality of treatment (surgery, coiling, no treatment), and later development of cerebral vasospasm. Plasmatic levels of IL-6 increased slightly, but no significant association was found. The levels of IL-1ß and TNFα were within the physiologic range in both CSF and plasma. CONCLUSIONS: Early dynamics of IL-6 in CSF are associated with a patient́s outcome. But it is difficult to use IL-6 alone for outcome prediction due to its high variability. The question is whether the dynamics of IL-6 could be used in combination with other early markers associated with brain injury. More detailed research is required to answer this question.

Cholinergic Anti-inflammatory Pathway and Stroke.

BACKGROUND: Stroke is devastating cerebrovascular event which is responsible for 6.7 million deaths each year worldwide. Inflammation plays an important role in the pathophysiology of stroke. Targeting inflammation after stroke is highly actual topic for both experimental and clinical research. METHODS: Research articles related to cholinergic anti-inflammatory pathway (CHAIP) and stroke were reviewed. The first part of review describes the basic characteristics of inflammatory response after stroke, main components and function of CHAIP. The second part reviews studies focused on CHAIP as a therapeutic target for ischemic and hemorrhagic stroke. Both pharmacological stimulation of α7 nAChR and vagus nerve stimulation after stroke are reviewed. RESULTS: Cholinergic anti-inflammatory pathway (CHAIP) is a physiological mechanism by which central nervous system regulates immune response and controls inflammation. Vagus nerve, spleen and α7 nicotinic acetylcholine receptor (α7 nAChR) are the main components of CHAIP. CONCLUSION: Targeting cholinergic anti-inflammatory pathway is a promising way of immunomodulation which attenuates inflammation in a complex manner without causing immunosuppression.

Middle cerebral artery aneurysms with intracerebral hematoma-the impact of side and volume on final outcome.

BACKGROUND: Middle cerebral artery aneurysms (MCA aneurysms) belong to the most frequent type of intracranial aneurysms forming an intracerebral hematoma. The consequences of the hematoma-the laterality, the impact of ICH volume and size of the aneurysm with the final outcome of these patients had not been studied in detail in this location, and we focused on the analysis of these factors. METHODS: Patients with MCA aneurysms and associated intracerebral hematomas with a volume ≥10 ml were studied; these were treated from January 2006 to December 2015. During this period, more than 700 patients with spontaneous subarachnoid hemorrhage were admitted to the Department of Neurosurgery, University Hospital Brno. The data were collected from the subarachnoid hemorrhage database of the unit and from the local hospital registry. All consecutive patients at the treating center were involved in this retrospective study. We collected clinical data such as age, gender, aneurysm location, preoperative hematoma size, Hunt-Hess grade and type of surgical procedures. We focused on the analysis of the final outcome [Glasgow Outcome Scale (GOS) score] in relation to ICH volume, side of bleeding and finally the relationship between aneurysm size and the volume of ICH. RESULTS: Fifty-eight patients with an MCA aneurysm and ICH were included; the mean age of this series was 59.4 years. Thirty-six patients (62%) had clinical status Hunt-Hess 4-5 on admission. The mean size of the intracerebral hematoma was 47.1 ml (10-133 ml). Most frequently, in 30 patients (52%), the hematoma had bled into the temporal lobe. Fifty three patients were operated on, and 5 were treated conservatively because of their poor condition. Twenty-three patients (40%) had a favorable Glasgow Outcome Scale score, and 35 (60%) had an unfavorable outcome including 20 patients (35%) who died. Of the 53 patients operated on, 20 (38%) underwent decompressive hemicraniectomy (DHC). Patients with an unfavorable outcome had significantly larger hematomas with a median size of 54 ml, whereas those with a favorable outcome had a median size of 26 ml (p = 0.0022). Larger hematomas were found on the right side. The cutoff volume for an unfavorable outcome in ICH was 25 ml. The outcomes were not related to the side of the ICH (p = 0.42), and the aneurysm size did not predetermine the ICH volume (p = 0.3159). CONCLUSION: Our study confirms the benefit of the active treatment of patients with MCA aneurysms and associated ICH. A significant proportion of these patients achieves a favorable outcome. No association between the side of bleeding and outcome was demonstrated. Hematomas larger than 25 ml have a greater tendency to lead to an unfavorable outcome. The treatment decision-making process should not differ for either side.

Association of circulating levels of RANTES and -403G/A promoter polymorphism to acute heart failure after STEMI and to cardiogenic shock.

Chemokines, including RANTES, play a crucial role in the processes of inflammation during cardiovascular disorders, including myocardial infarction, disease progression and complications. This study aimed to evaluate the role of RANTES -403G/A polymorphism and levels in circulation in processes of development and progression of myocardial infarction and cardiogenic shock. A total of 609 patients with ST-segment elevation myocardial infarction, 43 patients with cardiogenic shock and 130 control subjects were enrolled in the study. RANTES -403G/A promoter polymorphism and baseline serum RANTES levels were analyzed. In the present study, we associated RANTES -403G/A promoter polymorphism with acute heart failure in patients with myocardial infarction (p = 0.006) and ejection fraction 3 months after MI onset (p = 0.02). Further, a difference in circulating RANTES levels among controls and STEMI subjects, and a relation of serum levels with acute heart failure was observed (p = 0.03, p = 0.003, respectively). We found a significant difference when comparing cardiogenic shock patients and controls (p < 0.001), with the most significant difference between cardiogenic shock and AHF subgroup of STEMI patients (p < 0.001). We observed a decreasing tendency of serum RANTES levels with the severity of myocardial infarction and progression, with the lowest levels in patients with cardiogenic shock (cutoff level ≥80.4 ng/ml). Our results suggest the role of RANTES as a potential biomarker of cardiogenic shock and acute heart failure in the hospital phase after myocardial infarction.

Erythropoietin inhibits HIF-1α expression via upregulation of PHD-2 transcription and translation in an in vitro model of hypoxia-ischemia.

Hypoxia inducible factor (HIF)-1α is the central transcriptional factor for the regulation of oxygen-associated genes in response to hypoxia. Erythropoietin (EPO), a hematopoietic growth factor, increases oxygen availability during hypoxia/ischemia and is associated with neuroprotection following hypoxia-ischemia in laboratory models of stroke. However, EPO has failed to translate in a clinical setting. Thus, it is critical to elucidate the key players in EPO-induced neuroprotection. Our preliminary studies have shown that EPO, as a downstream gene of HIF, inhibits HIF-1α in a dose-dependent manner in an in vitro model of hypoxia-ischemia. This study is designed to elucidate the primary mediator of EPO-induced HIF-1α inhibition and subsequent cell survival/neuroprotection. Oxygen and glucose deprivation (OGD) of nerve growth factor-differentiated rat pheochromocytoma (PC-12) cells were used to model hypoxia-ischemia in an in vitro environment. The profile of HIF-1α, HIF-2α and prolyl hydroxylase domain 2 (PHD-2) expression; HIF-1α and prolyl hydroxylase (PHD-2) mRNA levels; matrix metalloproteinase (MMP)-9; and cell death was evaluated in the presence and absence of either EPO or PHD-2 inhibitor during OGD. Our findings showed that EPO treatment resulted in an increase in PHD-2 transcription and translation, inhibition of HIF-1α expression, reactive oxygen species formation, and MMP-9 activity, resulting in increased cell survival after OGD. We also observed that EPO-induced cell survival/neuroprotection was reversed by siRNA silencing of PHD-2. This led to the conclusion that PHD-2 is a key mediator of EPO-induced HIF-1α inhibition and subsequent neuroprotection in an in vitro model of hypoxia-ischemia.

Nasal administration of recombinant osteopontin attenuates early brain injury after subarachnoid hemorrhage.

BACKGROUND AND PURPOSE: Neuronal apoptosis is a key pathological process in subarachnoid hemorrhage (SAH)-induced early brain injury. Given that recombinant osteopontin (rOPN), a promising neuroprotectant, cannot pass through the blood-brain barrier, we aimed to examine whether nasal administration of rOPN prevents neuronal apoptosis after experimental SAH. METHODS: Male Sprague-Dawley rats (n=144) were subjected to the endovascular perforation SAH model. rOPN was administered via the nasal route and neurological scores as well as brain water content were evaluated at 24 and 72 hours after SAH induction. The expressions of cleaved caspase-3, phosphorylated focal adhesion kinase (FAK), and phosphorylated Akt were examined using Western blot analysis. Neuronal cell death was demonstrated with terminal deoxynucleotid transferase-deoxyuridine triphosphate (dUTP) nick end labeling. We also administered FAK inhibitor 14 and phosphatidylinositol 3-kinase inhibitor, Wortmannin, prior to rOPN to establish its neuroprotective mechanism. ELISA was used to measure rOPN delivery into the cerebrospinal fluid. RESULTS: Cerebrospinal fluid level of rOPN increased after its nasal administration. This was associated with improved neurological scores and reduced brain edema at 24 hours after SAH. rOPN increased phosphorylated FAK and phosphorylated Akt expressions and decreased caspase-3 cleavage, resulting in attenuation of neuronal cell death within the cerebral cortex. These effects were abolished by FAK inhibitor 14 and Wortmannin. CONCLUSIONS: Nasal administration of rOPN decreased neuronal cell death and brain edema and improved the neurological status in SAH rats, possibly through FAK-phosphatidylinositol 3-kinase-Akt-induced inhibition of capase-3 cleavage.

Modeling intracerebral hemorrhage in mice: injection of autologous blood or bacterial collagenase.

Spontaneous intracerebral hemorrhage (ICH) defines a potentially life-threatening neurological malady that accounts for 10-15% of all stroke-related hospitalizations and for which no effective treatments are available to date(1,2). Because of the heterogeneity of ICH in humans, various preclinical models are needed to thoroughly explore prospective therapeutic strategies(3). Experimental ICH is commonly induced in rodents by intraparenchymal injection of either autologous blood or bacterial collagenase(4). The appropriate model is selected based on the pathophysiology of hemorrhage induction and injury progression. The blood injection model mimics a rapidly progressing hemorrhage. Alternatively, bacterial collagenase enzymatically disrupts the basal lamina of brain capillaries, causing an active bleed that generally evolves over several hours(5). Resultant perihematomal edema and neurofunctional deficits can be quantified from both models. In this study, we described and evaluated a modified double injection model of autologous whole blood(6) as well as an ICH injection model of bacterial collagenase(7), both of which target the basal ganglia (corpus striatum) of male CD-1 mice. We assessed neurofunctional deficits and brain edema at 24 and 72 hr after ICH induction. Intrastriatal injection of autologous blood (30 µl) or bacterial collagenase (0.075U) caused reproducible neurofunctional deficits in mice and significantly increased brain edema at 24 and 72 hr after surgery (p<0.05). In conclusion, both models yield consistent hemorrhagic infarcts and represent basic methods for preclinical ICH research.

Role of the pituitary­adrenal axis in granulocyte-colony stimulating factor-induced neuroprotection against hypoxia­ischemia in neonatal rats.

Several reports indicate that the activity of the hypothalamic­pituitary­adrenal axis (HPA) is increased after a brain insult and that its down-regulation can improve detrimental outcomes associated with ischemic brain injuries.Granulocyte-colony stimulating factor (G-CSF) is a neuroprotective drug shown in the naïve rat to regulate hormones of the HPA axis. In this study we investigate whether G-CSF confers its neuroprotective properties by influencing the HPA response after neonatal hypoxia­ischemia (HI). Following the Rice­Vannucci model, seven day old rats (P7)were subjected to unilateral carotid ligation followed by 2.5 h of hypoxia. To test our hypothesis,metyrapone was administered to inhibit the release of rodent specific glucocorticoid, corticosterone, at the adrenal level. Dexamethasone, a synthetic glucocorticoid, was administered to agonize the effects of corticosterone.Our results show that both G-CSF and metyrapone significantly reduced infarct volume while dexamethasone treatment did not reduce infarct size even when combined with G-CSF. The protective effects of G-CSF do not include blood brain barrier preservation as suggested by the brain edema results. G-CSF did not affect the pituitary released adrenocorticotropic hormone (ACTH) levels in the blood plasma at 4 h, but suppressed the increase of corticosterone in the blood. The administration of G-CSF and metyrapone increased weight gain, and significantly reduced the Bax/Bcl-2 ratio in the brain while dexamethasone reversed the effects of G-CSF. The combination of G-CSF and metyrapone significantly decreased caspase-3 protein levels in the brain, and the effect was antagonized by dexamethasone.We report that G-CSF is neuroprotective in neonatal HI by reducing infarct volume, by suppressing the HI-induced increase of the Bax/Bcl-2 ratio, and by decreasing corticosterone in the blood. Metyrapone was able to confer similar neuroprotection as G-CSF while dexamethasone reversed the effects of G-CSF. In conclusion, we show that decreasing HPA axis activity is neuroprotective after neonatal HI, which can be conferred by administering G-CSF.

Inhibition of Rho kinase by hydroxyfasudil attenuates brain edema after subarachnoid hemorrhage in rats.

The blood-brain barrier (BBB) disruption and brain edema are important pathophysiologies of early brain injury after subarachnoid hemorrhage (SAH). This study is to evaluate whether Rho kinase (Rock) enhances BBB permeability via disruption of tight junction proteins during early brain injury. Adult male rats were assigned to five groups; Sham-operated, SAH treated with saline, a Rock inhibitor hydroxyfasudil (HF) (10 mg/kg) treatment at 0.5 h after SAH, HF treatment at 0.5 and 6 h (10 mg/kg, each) after SAH, and another Rock inhibitor Y27632 (10 mg/kg) treatment at 0.5 h after SAH. The perforation model of SAH was performed and neurological score and brain water content were evaluated 24 and 72 h after surgery. Evans blue extravasation, Rock activity assay, and western blotting analyses were evaluated 24 h after surgery. Treatment of HF significantly improved neurological scores 24 h after SAH. Single treatment with HF and Y27632, and two treatments with HF reduced brain water content in the ipsilateral hemisphere. HF reduced Evans blue extravasation in the ipsilateral hemisphere after SAH. Rock activity increased 24 h after SAH, and HF reversed the activity. SAH significantly decreased the levels of tight junction proteins, occludin and zonula occludens-1 (ZO-1), and HF preserved the levels of occluding and ZO-1 in ipsilateral hemisphere. In conclusion, HF attenuated BBB permeability after SAH, possibly by protection of tight junction proteins.

α7 nicotinic acetylcholine receptor agonism confers neuroprotection through GSK-3ß inhibition in a mouse model of intracerebral hemorrhage.

BACKGROUND AND PURPOSE: Perihematomal edema formation and consequent cell death contribute to the delayed brain injury evoked by intracerebral hemorrhage (ICH). We aimed to evaluate the effect of α7 nicotinic acetylcholine receptor (α7nAChR) stimulation on behavior, brain edema, and neuronal apoptosis. Furthermore, we aimed to determine the role of the proapoptotic glycogen synthase kinase-3ß (GSK-3ß) after experimental ICH. METHODS: Male CD-1 mice (n=109) were subjected to intracerebral infusion of autologous blood (n=88) or sham surgery (n=21). ICH animals received vehicle administration, 4 or 12 mg/kg of α7nAChR agonist PHA-543613, 12 mg/kg of α7nAChR agonist PNU-282987, 6 mg/kg of α7nAChR antagonist methyllycaconitine (MLA), 15 µg/kg of phosphatidylinositol 3-kinase (PI3K) inhibitor wortmannin, or PHA-543613 combined with MLA or wortmannin. Behavioral deficits and brain water content were evaluated at 24 and 72 hours after surgery. Western blotting and immunofluorescence staining were used for the quantification and localization of activated Akt (p-Akt), GSK-3ß (p-GSK-3ß), and cleaved caspase-3 (CC3). Neuronal cell death was quantified through terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL). RESULTS: α7nAChR stimulation improved neurological outcome and reduced brain edema at 24 and 72 hours after surgery (P<0.05 compared with vehicle). Furthermore, PHA-543613 treatment increased p-Akt and decreased p-GSK-3ß and CC3 expressions in the ipsilateral hemisphere (P<0.05, respectively), which was reversed by MLA and wortmannin. P-Akt, p-GSK-3ß, and CC3 were generally localized in neurons. PHA-543613 reduced neuronal cell death in the perihematomal area (P<0.05). CONCLUSIONS: α7nAChR stimulation improved functional and morphological outcomes after experimental ICH in mice. PHA-543613 reduced the expression of proapoptotic GSK-3ß through the PI3K-Akt signaling pathway.

Minocycline improves functional outcomes, memory deficits, and histopathology after endovascular perforation-induced subarachnoid hemorrhage in rats.

Subarachnoid hemorrhage (SAH) results in significant long-lasting cognitive dysfunction. Therefore, evaluating acute and long-term outcomes after therapeutic intervention is important for clinical translation. The aim of this study was to use minocycline, a known neuroprotectant agent, to evaluate the long-term benefits in terms of neurobehavior and neuropathology after experimental SAH in rats, and to determine which neurobehavioral test would be effective for long-term evaluation. SAH was induced by endovascular perforation in adult male Sprague-Dawley rats (n=118). The animals were treated with intraperitoneal injection of minocycline (45 mg/kg or 135 mg/kg) or vehicle 1 h after SAH induction. In the short-term, animals were euthanized at 24 and 72 h for evaluation of neurobehavior, brain water content, and matrix metalloproteinase (MMP) activity. In the long-term, neurobehavior was evaluated at days 21-28 post-SAH, and histopathological analysis was done at day 28. High-dose but not low-dose minocycline reduced brain water content at 24 h, and therefore only the high-dose regimen was used for further evaluation, which reduced MMP-9 activity at 24 h. Further, high-dose minocycline improved spatial memory and attenuated neuronal loss in the hippocampus and cortex. The rotarod, T-maze, and water maze tests, but not the inclined plane test, detected neurobehavioral deficits in SAH rats at days 21-28. This study demonstrates that minocycline attenuates long-term functional and morphological outcomes after endovascular perforation-induced SAH. Long-term neurobehavioral assessments using the rotarod, T-maze, and water maze tests could be useful to evaluate the efficacy of therapeutic intervention after experimental SAH.

α7 nicotinic acetylcholine receptor agonist PNU-282987 attenuates early brain injury in a perforation model of subarachnoid hemorrhage in rats.

BACKGROUND AND PURPOSE: Early brain injury is an important pathological process after subarachnoid hemorrhage (SAH). The goal of this study was to evaluate whether the α7 nicotinic acetylcholine receptor (α7nAChR) agonist PNU-282987 attenuates early brain injury after SAH and whether α7nAChR stimulation is associated with down-regulation of caspase activity via phosphatidylinositol 3-kinase-Akt signaling. METHODS: The perforation model of SAH was performed, and neurological score, body weight loss, and brain water content were evaluated 24 and 72 hours after surgery. Western blot and immunohistochemistry were used for quantification and localization of phosphorylated Akt and cleaved caspase 3. Neuronal cell death was quantified with TUNEL staining. α7nAChR antagonist methylcaconitine and phosphatidylinositol 3-kinase inhibitor wortmannin were used to manipulate the proposed pathway, and results were quantified with Western blot. RESULTS: PNU-282987 improved neurological deficits both 24 and 72 hours after surgery and reduced brain water content in left hemispheres 24 hours after surgery. PNU-282987 significantly increased phosphorylated Akt levels and significantly decreased cleaved caspase 3 levels in ipsilateral hemispheres after SAH. Methylcaconitine and wortmannin reversed effects of treatment. Phosphorylated Akt and cleaved caspase 3 were colocalized to neurons in the ipsilateral basal cortex. Phosphorylated Akt was mainly localized in TUNEL-negative cells. PNU-282987 significantly reduced neuronal cell death in the ipsilateral basal cortex. CONCLUSIONS: α7nAChR stimulation decreased neuronal cell death and brain edema and improved neurological status in a rat perforation model of SAH. α7nAChR stimulation is associated with increasing phosphorylation of Akt and decreasing cleaved caspase 3 levels in neurons.

Sampling of CSF via the Cisterna Magna and Blood Collection via the Heart Affects Brain Water Content in a Rat SAH Model.

The aim of this study was to evaluate whether sampling of cerebrospinal fluid (CSF) via the cisterna magna and of blood via the heart affects brain water content in a rat subarachnoid hemorrhage (SAH) model. Twenty-nine animals were divided into four groups: sham-operated group with sampling of CSF and blood (Sham S+), sham-operated group without sampling of CSF and blood (Sham S-), SAH group with sampling of CSF and blood (SAH S+), and SAH without sampling of CSF and blood (SAH S-). SAH was induced via endovascular perforation of the left internal carotid artery bifurcation. Cerebrospinal fluid via the cisterna magna and blood via cardiac puncture was collected in the Sham S+ and SAH S+ groups before killing the animals for brain water content measurements. Left hemisphere brain water content was significantly higher in the SAH S- group compared with the Sham S- group (p< 0.05) and in Sham S+ group compared with the Sham S- group (p<0.05). There was no significant difference in brain water content of the left hemisphere between the SAH S+ and Sham S+ groups (p=NS). There was no significant difference in brain water content in other parts of brains. Sampling of CSF and blood affected brain water content in Sham animals and therefore it is not accurate to use these values from Sham animals for comparison with SAH animals.

Tyrosine phosphatase inhibition attenuates early brain injury after subarachnoid hemorrhage in rats.

PURPOSE: Sodium orthovanadate (SOV) is a representative tyrosine phosphatase inhibitor and has been shown to ameliorate neuronal injury in cerebral ischemia. We hypothesized that tyrosine phosphatase inhibition by SOV might attenuate early brain injury after subarachnoid hemorrhage (SAH) in this study. METHODS: The endovascular perforation model of SAH was produced and animals were randomly assigned to sham-operated rats, saline-treated (vehicle), and 10 mg/kg of SOV-treated SAH rats. Drugs were injected intraperitoneally immediately after SAH induction. Neurological score and brain water content (BWC) were assessed at 24 h after SAH. Cell injury was studied by terminal deoxynucleotidyl transferase-mediated uridine 5'-triphosphate-biotin nick end-labeling (TUNEL) at 24 h after SAH. RESULTS: Severity of SAH and mortality in SOV-treated rats was similar to that of the saline group. SOV significantly decreased BWC and improved neurological score at 24 h after SAH compared with the saline group. SOV decreased TUNEL-positive cells at 24 h after SAH compared with the saline group. CONCLUSIONS: These data suggest that tyrosine phosphatase inhibition by SOV ameliorates early brain injury after SAH.