Experimental Subarachnoid Hemorrhage Model Research Articles

RNF216 mediates neuronal injury following experimental subarachnoid hemorrhage through the Arc/Arg3.1-AMPAR pathway.

Subarachnoid hemorrhage (SAH), mostly caused by aneurysm rupture, is a pathological condition associated with oxidative stress and neuroinflammation. Toll-like receptors (TLRs) are a family of key regulators of neuroinflammation, and RNF216 is an E3 ubiquitin-protein ligase that regulates TLRs via ubiquitination and proteolytic degradation. However, the role of RNF216 in SAH has not been determined. In this study, we investigated the biological function of RNF216 in experimental SAH models both in vitro and in vivo. The expression of RNF216 was found to be upregulated in cortical neurons after oxyhemoglobin (OxyHb) treatment, and increased RNF216 expression was also observed in brain tissues in the single-hemorrhage model of SAH. Downregulation of RNF216 expression by short interfering RNA (siRNA) transfection significantly reduced cytotoxicity and apoptosis after OxyHb exposure. The results of western blot showed that the RNF216-mediated neuronal injury in vitro was associated with the regulation of the Arc-AMPAR pathway, which was related to intracellular Ca2+ dysfunction, as evidenced by Ca2+ imaging. In addition, knockdown of RNF216 in vivo using intraventricular injection of siRNA was found to attenuate brain injury and neuroinflammation via the Arc-AMPAR pathway after SAH in the animal model. In summary, we demonstrated that silence of RNF216 expression protects against neuronal injury and neurological dysfunction in experimental SAH models. These data support for the first time that RNF216 may represent a novel candidate for therapies against SAH.

Effects of Lutein on Brain Damage and Vasospasm in an Experimental Subarachnoid Hemorrhage Model

Vasospasm developing after subarachnoid hemorrhage (SAH) is an important cause of mortality and morbidity. Lutein is a carotenoid with antioxidant and anti-inflammatory properties. The aim of present study was to investigate effects of lutein on the basilar artery and nerve tissues. Wistar rats were randomly divided into 3 groups: control (group 1), SAH (group 2), and SAH treated with lutein (group 3). Lutein was administered for 3 days by means of orogastric gavage. Basilar artery lumen area, wall thickness, serum total antioxidant status, serum total oxidant status, and oxidative stress index were calculated. Histopathologic and immunohistochemical analyses were conducted. No statistically significant difference was found between groups in terms of wall thickness; lumen area; and serum total antioxidant status, serum total oxidant status, and oxidative stress index values. A statistically significant difference was found between groups colored with terminal deoxynucleotidyl transferase dUTP nick end labeling (P < 0.005). Post hoc analysis was used to examine the results between groups. Results of group 1 and group 3 were equal (P= 1) and lower than group 2 (P= 0.04 and P= 0.006, respectively). Lutein was found to have a positive effect on width of the basilar artery lumen area. Therefore, positive effects of lutein on vasospasm might be statistically significant if lutein is administered at higher doses. Lutein was found to be effective in preventing brain damage after SAH. To our knowledge, this study is the first in the literature to examine the effect of lutein on vasospasm and brain damage after SAH.

CX3CL1/CX3CR1 axis attenuates early brain injury via promoting the delivery of exosomal microRNA-124 from neuron to microglia after subarachnoid hemorrhage

BackgroundMicroglial activation-mediated neuroinflammation is a major contributor to early brain injury (EBI) after subarachnoid hemorrhage (SAH). MicroRNA-124 (miR-124) is the most abundant miRNAs in the central nervous system (CNS) and plays a vital role in microglial activation by targeting protein CCAAT-enhancer-binding protein α (C/EBPα). It has been reported that the CX3CL1/CX3CR1 axis is involved in the delivery of miR-124 from neurons to microglia.MethodsAn experimental rat SAH model was established by injecting autologous arterial blood into the prechiasmatic cistern, and cultured primary neurons and microglia were exposed to oxyhemoglobin to mimic SAH in vitro. We additionally exploited specific expression plasmids encoding CX3CL1 and CX3CR1.ResultsWe observed significant decreases in CX3CL1 and CX3CR1 in the brain tissues of SAH patients. We also observed decreases in the levels of CX3CL1 in neurons and CX3CR1 in microglia after SAH in rats. Moreover, microglia exhibited an activated phenotype with macrophage-like morphology and high levels of CD45 and major histocompatibility complex (MHC) class II after SAH. After overexpression of CX3CL1/CX3CR1, the level of CD45 and MHC class II and the release of inflammatory factors tumor necrosis factor α, interleukin 1α and complement 1q were significantly decreased. There was also increased neuronal degeneration and behavior dysfunction after SAH, both of which were inhibited by CX3CL1/CX3CR1 overexpression. Additionally, we found that the delivery of exosomal miR-124 from neurons to microglia was significantly reduced after SAH, accompanied by an increase in C/EBPα expression, and was inhibited by CX3CL1/CX3CR1 overexpression. In conclusion, the CX3CL1/CX3CR1 axis may play protective roles after SAH by promoting the delivery of exosomal miR-124 to microglia and attenuate microglial activation and neuroinflammation.ConclusionsCX3CL1/CX3CR1 axis may be a potential intervention target for the inhibition of SAH-induced EBI by promoting exosome transport of miR-124 to microglia.

Hydrogen Sulfide Reduces Cognitive Impairment in Rats After Subarachnoid Hemorrhage by Ameliorating Neuroinflammation Mediated by the TLR4/NF-κB Pathway in Microglia

Background and Aims: Cognitive impairment is one of the major complications of subarachnoid hemorrhage (SAH) and is closely associated with neuroinflammation. Hydrogen sulfide (H2S) has been shown to have an anti-inflammatory effect and reduce cognitive impairment in neurodegenerative diseases, but its effects in SAH have been little studied. This study aimed to investigate the effects of H2S on cognitive impairment after SAH and the possible underlying mechanisms.Methods: Forty-eight male Sprague–Dawley (SD) rats were randomly divided into three groups: a sham group, a SAH group, and a SAH + NaHS (an H2S donor) group. The endovascular perforation technique was used to establish the experimental SAH model. NaHS was administered intraperitoneally. An active avoidance test (AAT) was performed to investigate cognitive function. The expression of TNF-α, toll-like receptor 4 (TLR4), and NF-κB p65 in the hippocampus was measured by Western blot and immunohistochemistry. The types of cells expressing TNF-α were detected by double immunofluorescence staining.Results: Compared to that in the sham group, the learning and memory ability of rats in the SAH group was damaged. Furthermore, the expression of TNF-α, TLR4, and NF-κB p65 in the hippocampus was elevated in the SAH group (p < 0.05). TNF-α was mainly expressed in activated microglia, which was consistent with the expression of TLR4. Treatment with NaHS significantly decreased the cognitive impairment of rats after SAH and simultaneously reduced the expression of TNF-α, TLR4, and NF-κB p65 and alleviated the nuclear translocation of NF-κB p65 (p < 0.05).Conclusions: The neuroinflammation reaction in microglia contributes to cognitive impairment after SAH. H2S reduced the cognitive impairment of rats after SAH by ameliorating neuroinflammation in microglia, potentially via the TLR4/NF-κB pathway.

Neuroprotective role of glutathione peroxidase 4 in experimental subarachnoid hemorrhage models

Background and purposeEarly brain injury is an essential pathological process after subarachnoid hemorrhage (SAH), with many cell death modalities. Ferroptosis is a newly discovered regulated cell death caused by the iron-dependent accumulation of lipid peroxidation, which can be prevented by glutathione peroxidase 4 (GPX4). Our study aimed to investigate the role of GPX4 in neuronal cell death after experimental SAH. MethodsIn vivo experimental SAH was induced by injecting autologous arterial blood into the prechiasmatic cistern in male Sprague-Dawley rats. Meanwhile, the in vitro SAH model was performed with primary rat cortical neurons cultured in medium containing hemoglobin (Hb). Adenovirus was used to overexpress GPX4 before experimental SAH. GPX4 expression was detected by western blot and immunofluorescence experiments. Malondialdehyde (MDA) was measured to evaluate the level of lipid peroxidation. Nissl staining was employed to assess cell death in vivo, whereas lactate dehydrogenase (LDH) release was used to evaluate cell damage in vitro. The brain water content and neurological deficits were evaluated to determine brain injury. ResultsEndogenous GPX4 was mainly expressed in neurons, and its expression decreased at 24 h after experimental SAH. Overexpression of GPX4 significantly reduced lipid peroxidation and cell death in the experimental SAH models both in vivo and in vitro. Moreover, overexpression of GPX4 ameliorated brain edema and neurological deficits at 24 h after SAH. ConclusionsThe decrease of GPX4 expression potentially plays an important role in ferroptosis during early brain injury after SAH. Overexpression of GPX4 has a neuroprotective effect after SAH.

Microthrombi Correlates With Infarction and Delayed Neurological Deficits After Subarachnoid Hemorrhage in Mice.

Delayed neurological deficits are a devastating consequence of subarachnoid hemorrhage (SAH), which affects about 30% of surviving patients. Although a very serious concern, delayed deficits are understudied in experimental SAH models; it is not known whether rodents recapitulate the delayed clinical decline seen in SAH patients. We hypothesized that mice with SAH develop delayed functional deficits and that microthrombi and infarction correlate with delayed decline. Adult C57BL/6J mice of both sexes were subjected to endovascular perforation to induce SAH. Mice were allowed to survive for up to 1 week post-ictus and behavioral performance was assessed daily. Postmortem microthrombi, large artery diameters (to assess vasospasm), and infarct volume were measured. These measures were analyzed for differences between SAH mice that developed delayed deficits and SAH mice that did not get delayed deficits. Correlation analyses were performed to identify which measures correlated with delayed neurological deficits, sex, and infarction. Twenty-three percent of males and 47% of females developed delayed deficits 3 to 6 days post-SAH. Female mice subjected to SAH had a significantly higher incidence of delayed deficits than male mice with SAH. Mice that developed delayed deficits had significantly more microthrombi and larger infarct volumes than SAH mice that did not get delayed deficits. Microthrombi positively correlated with infarct volume, and both microthrombi and infarction correlated with delayed functional deficits. Vasospasm did not correlate with either infarction delayed functional deficits. We discovered that delayed functional deficits occur in mice following SAH. Sex differences were seen in the prevalence of delayed deficits. The mechanism by which microthrombi cause delayed deficits may be via formation of infarcts.

Amelioration of Cerebral Vasospasm and Secondary Injury by Vigabatrin After Experimental Subarachnoid Hemorrhage in the Rabbit

Vigabatrin, an antiepileptic drug, increases the level of gamma aminobutyric acid in the brain by inhibiting its catabolism. Because gamma aminobutyric acid has been proved to have vasodilatory effects, in the present study, we investigated the effect of vigabatrin to treat experimental subarachnoid hemorrhage (SAH)-induced vasospasm. A total of 30 New Zealand white rabbits were divided into 3 groups of 10 each: the control group, SAH group, and vigabatrin group. Experimental SAH was established by injection of autologous arterial blood into the cisterna magna. In the vigabatrin group, the rabbits were administered vigabatrin for 3 days after induction of the SAH. The first dose of vigabatrin was given 2 hours after SAH induction. A daily dose of 500 mg/kg vigabatrin was administered intraperitoneally. After 3 days, the rabbits were sacrificed, and the brains were removed, together with the cerebellum and brainstem. The basilar artery wall thickness and lumen areas were measured. The neuronal degeneration in the hippocampus (CA1, CA3, and dentate gyrus) was also evaluated. The arterial wall thickness of the vigabatrin group was less than that in the SAH group (P < 0.001), and the mean luminal area of the vigabatrin group was greater than that in the SAH group (P < 0.001). Additionally, the hippocampal neuronal degeneration score of the vigabatrin group was lower than that of the SAH group (P < 0.001). These findings have indicated that vigabatrin has a vasodilatory effect in an experimental SAH model in the rabbit. Moreover, it showed a neuroprotective effect in the hippocampal neurons against secondary injury induced by SAH.

The effect of pentoxifylline on cerebral vasospasm following experimental subarachnoid hemorrhage

Objects Cerebral vasospasm is an important event that occurs following subarachnoid hemorage which has significant mortality and morbidity. The goal in this study was to investigate the effect of pentoxifylline on vasospasm in an experimental subarachnoid hemorrhage model. Methods In this study, 20 male New Zeland White rabbits weighing 3000–3500 g were assigned randomly to four groups. Animals in group 1 served as controls. Animals in group two received only intravenous pentoxifylline injection 3 times in 12 h intervals. In group 3, SAH was induced and no injection was given. Animals in group 4 received intravenous pentoxifylline (6 mg/kg) injections 3 times at 12th, 24th and 36th hours after subarachnoid hemorrhage induction. All animals were sacrificed and basilar arteries were removed at 48th hour. Basilar artery vessel diameters, wall thicknesses and luminal section areas were measured with Spot for Windows version 4.1. Statistical analysis was performed using ANOVA and Kruskall–Wallis tests. Results Mean basilar artery luminal section areas and luminal diameters in group 4 were significantly higher compared to group 3 (p < 0.05). Basilar artery wall thicknesses and were found to be higher in group 3 than in other groups and this was also statistically significant (p < 0.05). Conclusion Our study demonstrated that intravenous administration of pentoxifylline significantly decreases vasospasm after subarachnoid hemorrhage.

The ESAS-score: A histological severity grading system of subarachnoid hemorrhage using the modified double hemorrhage model in rats

ObjectiveThe amount of extravasated blood is an established surrogate marker for subarachnoid hemorrhage (SAH) severity, which varies in different experimental SAH (eSAH) models. A comprehensive eSAH grading system would allow a more reliable correlation of outcome parameters with SAH severity. The aim of this study was to define a severity score for eSAH related to the Fisher-Score in humans.Material and methodsSAH was induced in 135 male rats using the modified double hemorrhage model. A sham group included 8 rats, in which saline solution instead of blood was injected. Histological analysis with HE(hematoxylin-eosin)-staining for the visualization of blood was performed in all rats on day 5. The amount and distribution of blood within the subarachnoid space and ventricles (IVH) was analyzed.ResultsThe mortality rate was 49.6% (71/143). In all except five SAH rats, blood was visible within the subarachnoid space. As expected, no blood was detected in the sham group. The following eSAH severity score was established (ESAS-score): grade I: no SAH visible; grade II: local or diffuse thin SAH, no IVH; grade III: diffuse / thick layers of blood, no IVH; grade IV: additional IVH. Grade I was seen in five rats (7.9%), grade II in 28.6% (18/63), grade III in 41.3% (26/63) and grade IV in 22.2% (14/63) of the rats with eSAH.ConclusionThe double hemorrhage model allows the induction of a high grade SAH in more than 60% of the rats, making it suitable for the evaluation of outcome parameters in severe SAH.

Crosstalk between soluble PDGF-BB and PDGFRβ promotes astrocytic activation and synaptic recovery in the hippocampus after subarachnoid hemorrhage.

Platelet-derived growth factor receptor β (PDGFRβ) dynamically changes after brain injury, possibly mediating the neuroprotective role of soluble homodimers of the platelet-derived growth factor β subunit (PDGF-BB) that is secreted by microcirculation cells. The aim of this study was to determine whether binding of PDGF-BB to astrocytic PDGFRβ enhanced crosstalk among the various components of the neurovascular unit, leading to synaptic recovery after subarachnoid hemorrhage (SAH). The soluble PDGF-BB from the cerebrospinal fluid (CSF) of patients with SAH was measured. The relationship between PDGF-BB treatment and astrocytic PDGFRβ signaling was further explored in vivo and in vitro in experimental SAH models. Compared with the levels in the control samples, the PDGF-BB protein levels in the CSF of patients with SAH were significantly increased. After the generation of experimental SAH, astrocyte activation markers were markedly induced by the binding of PDGF-BB to astrocytic PDGFRβ, accompanied by improved levels of synaptic recovery and cognitive function. Soluble PDGF-BB and astrocytic PDGFRβ signaling are essential for the neuroprotective effect in the hippocampus and the coculture system in vitro after SAH that otherwise leads to cognitive dysfunction and neuronal damage.-Zhou, X., Wu, Q., Lu, Y., Zhang, X., Lv, S., Shao, J., Zhou, Y., Chen, J., Hou, L., Huang, C., Zhang, X. Crosstalk between soluble PDGF-BB and PDGFRβ promotes astrocytic activation and synaptic recovery in the hippocampus after subarachnoid hemorrhage.

Tetramethylpyrazine Nitrone Reduces Oxidative Stress to Alleviate Cerebral Vasospasm in Experimental Subarachnoid Hemorrhage Models.

Cerebral vasospasm is one of the deleterious complications after subarachnoid hemorrhage (SAH), leading to delayed cerebral ischemia and permanent neurological deficits or even death. Free radicals and oxidative stress are considered as crucial causes contributing to cerebral vasospasm and brain damage after SAH. Tetramethylpyrazine nitrone (TBN), a derivative of the clinically used anti-stroke drug tetramethylpyrazine armed with a powerful free radical scavenging nitrone moiety, has been reported to prevent brain damage from ischemic stroke. The present study aimed to investigate the effects of TBN on vasospasm and brain damage after SAH. Two experimental SAH models were used, a rat model by endovascular perforation and a rabbit model by intracisternal injection of autologous blood. The effects of TBN on SAH were evaluated assessing basilar artery spasm, neuronal apoptosis, and neurological deficits. TBN treatment significantly attenuated vasospasm, improved neurological behavior functions and reduced the number of apoptotic neurons in both the SAH rats and rabbits. Mechanistically, TBN suppressed the increase in 3-nitrotyrosine and 8-hydroxy-2-deoxyguanosine immuno-positive cells in the cortex of SAH rat brain. Western blot analyses indicated that TBN effectively reversed the altered expression of Bcl-2, Bax and cytochrome C, and up-regulated nuclear factor erythroid-derived 2-like 2 (Nrf2) and hemeoxygenase-1 (HO-1) protein expressions. In the in vitro studies, TBN inhibited H2O2-induced bEnd.3 cell apoptosis and reduced ROS generation. Additionally, TBN alleviated the contraction of rat basilar artery rings induced by H2O2 ex vivo. In conclusion, TBN ameliorated SAH-induced cerebral vasospasm and neuronal damage. These effects of TBN may be attributed to its anti-oxidative stress effect and up-regulation of Nrf2/HO-1.

Neuroinflammation and Microvascular Dysfunction After Experimental Subarachnoid Hemorrhage: Emerging Components of Early Brain Injury Related to Outcome.

Aneurysmal subarachnoid hemorrhage has a high mortality rate and, for those who survive this devastating injury, can lead to lifelong impairment. Clinical trials have demonstrated that cerebral vasospasm of larger extraparenchymal vessels is not the sole contributor to neurological outcome. Recently, the focus of intense investigation has turned to mechanisms of early brain injury that may play a larger role in outcome, including neuroinflammation and microvascular dysfunction. Extravasated blood after aneurysm rupture results in a robust inflammatory response characterized by activation of microglia, upregulation of cellular adhesion molecules, recruitment of peripheral immune cells, as well as impaired neurovascular coupling, disruption of the blood-brain barrier, and imbalances in endogenous vasodilators and vasoconstrictors. Each of these phenomena is either directly or indirectly associated with neuronal death and brain injury. Here, we review recent studies investigating these various mechanisms in experimental models of subarachnoid hemorrhage with special emphasis on neuroinflammation and its effect on microvascular dysfunction. We discuss the various therapeutic targets that have risen from these mechanistic studies and suggest the utility of a multi-targeted approach to preventing delayed injury and improving outcome after subarachnoid hemorrhage.

The Acute Phase of Experimental Subarachnoid Hemorrhage: Intracranial Pressure Dynamics and Their Effect on Cerebral Blood Flow and Autoregulation.

Clinical presentation and neurological outcome in subarachnoid hemorrhage (SAH) is highly variable. Aneurysmal SAH (aSAH) is hallmarked by sudden increase of intracranial pressure (ICP) and acute hypoperfusion contributing to early brain injury (EBI) and worse outcome, while milder or non-aneurysmal SAH with comparable amount of blood are associated with better neurological outcome, possibly due to less dramatic changes in ICP. Acute pressure dynamics may therefore be an important pathophysiological aspect determining neurological complications and outcome. We investigated the influence of ICP variability on acute changes after SAH by modulating injection velocity and composition in an experimental model of SAH. Five hundred microliters of arterial blood (AB) or normal saline (NS) were injected intracisternally over 1 (AB1, NS1), 10 (AB10, NS10), or 30min (AB30) with monitoring for 6h (n= 68). Rapid blood injection resulted in highest ICP peaks (AB1 median 142.7mmHg [1.Q 116.7-3.Q 230.6], AB30 33.42mmHg [18.8-38.3], p< 0.001) and most severe hypoperfusion (AB1 16.6% [11.3-30.6], AB30 44.2% [34.8-59.8]; p< 0.05). However, after 30min, all blood groups showed comparable ICP elevation and prolonged hypoperfusion. Cerebral autoregulation was disrupted initially due to the immediate ICP increase in all groups except NS10; only AB1, however, resulted in sustained impairment of autoregulation, as well as early neuronal cell loss. Rapidity and composition of hemorrhage resulted in characteristic hyperacute hemodynamic changes, with comparable hypoperfusion despite different ICP ranges. Only rapid ICP increase was associated with pronounced and early, but sustained disruption of cerebral autoregulation, possibly contributing to EBI.

Neuroprotective Effects of Hesperidin on Cerebral Vasospasm After Experimental Subarachnoid Hemorrhage in Rats: Biochemical, Pathologic, and Histomorphometric Analysis

We examined the protective effects of hesperidin on cerebral vasospasm by establishing an experimental rat model of subarachnoid hemorrhage and performing biochemical, pathologic, and histomorphometric analysis on these data. Forty albino Wistar rats were randomly divided into 5 groups of n= 8 in each: group (G)1, no experimental interventions; G2, subjected to subarachnoid hemorrhage; G3, subjected to subarachnoid hemorrhage and administered saline (100 mg/kg); G4, subjected to subarachnoid hemorrhage and treated with low-dose hesperidin (50 mg/kg); and G5, subjected to subarachnoid hemorrhage and treated with high-dose hesperidin (100 mg/kg). Subarachnoid hemorrhage was created by injecting 0.15 cc of autologous blood taken from the rat-tail artery and injected into the cisterna magna from the craniocervical junction. Drugs were administered intraperitoneally as twice daily doses for 48 hours. Rats were euthanized at the end of this period. No statistically significant decrease was observed in malondialdehyde levels, which is the end-product of lipid peroxidation, among the drug groups (G4 and G5). Thin sections prepared from the basilar artery were examined morphologically. Severe luminal narrowing and vessel-wall thickening were observed in the subarachnoid hemorrhage groups (G2, G3). In the hesperidin-administered groups (G4, G5), it was determined that vessel wall thickness measurements revealed thinner walls than in the subarachnoid hemorrhage groups (G2, G3) and the luminal diameters were significantly larger than in the subarachnoid hemorrhage groups (G2, G3). These findings suggest that hesperidin has no effect on malondialdehyde-associated lipid-peroxidation activity; however, it might be useful in subarachnoid hemorrhage therapy because of its beneficial effects on vessel wall thickness and luminal diameters.

Inhibition of Heat Shock Protein 90 by 17-AAG Reduces Inflammation via P2X7 Receptor/NLRP3 Inflammasome Pathway and Increases Neurogenesis After Subarachnoid Hemorrhage in Mice

Subarachnoid hemorrhage (SAH) is a life-threatening cerebrovascular disease that usually has a poor prognosis. Heat shock proteins (HSPs) have been implicated in the mechanisms of SAH-associated damage, including increased inflammation and reduced neurogenesis. The aim of this study was to investigate the effects of HSP90 inhibition on inflammation and neurogenesis in a mouse model of experimental SAH induced by endovascular surgery. Western blotting showed HSP90 levels to be decreased, while neurogenesis, evaluated by 5-bromo-2’-deoxyuridine (BrdU) immunohistochemistry, was decreased in the hippocampuses of SAH mice. SAH also induced pro-inflammatory factors such as interleukin-1β (IL-1β), capase-1 and the NLRP3 inflammasome. However, intraperitoneal administration of the specific HSP90 inhibitor 17-allylamino-17-demethoxygeldanamycin (17-AAG) reduced the levels of HSP90, NLRP3, ASC, caspase-1 and IL-1β, while increasing the levels of brain-derived neurotrophic factor and doublecortin (DCX), as well as the number of BrdU-positive cells in SAH mice. In addition, 17-AGG improved short- and long-term neurobehavioral outcomes. The neuroprotective and anti-inflammatory effects of 17-AGG were reversed by recombinant HSP90 (rHSP90); this detrimental effect of HSP90 was inhibited by the specific P2X7 receptor (P2X7R) inhibitor A438079, indicating that SAH-induced inflammation and inhibition of neurogenesis were likely mediated by HSP90 and the P2X7R/NLRP3 inflammasome pathway. HSP90 inhibition by 17-AAG may be a promising therapeutic strategy for the treatment of SAH.

Protective effects of astaxanthin on subarachnoid hemorrhage-induced early brain injury: Reduction of cerebral vasospasm and improvement of neuron survival and mitochondrial function

The purpose of this study was to evaluate the neuroprotective effects of astaxanthin on early brain injury (EBI) caused by subarachnoid hemorrhage (SAH) in rats and to explore possible molecular mechanisms. Experimental SAH model was introduced in adult male SD rats by injecting autologous arterial blood into the prechiasmatic cistern. Astaxanthin (75 mg/kg bodyweight) or olive oil was administered by oral gavage at 3 h after SAH. Our results showed that astaxanthin attenuated SAH-induced cerebral vasospasm and reduced neuronal apoptosis. Astaxanthin inhibited mitochondria-associated neuron apoptosis in the prefrontal cortex after SAH: increased mitochondrial membrane potential, decreased Bax/Bcl-2 ratio, inhibited cytochrome C release in cytoplasm, and suppressed caspase-3 enzyme activity. Furthermore, the cerebral expression levels of synaptic proteins (Synapsin-1, postsynaptic density-95 and growth-associated protein-43) and nerve growth and neuronal differentiation factors (brain-derived neurotropic factor and purine-rich binding protein-alpha) were reduced following SAH. Astaxanthin partly restored their expression. In conclusion, our current work demonstrates that astaxanthin attenuates SAH-induced EBI, possibly by improving neuronal survival and mitochondrial function.

Association between vasoactive peptide urotensin II in plasma and cerebral vasospasm after aneurysmal subarachnoid hemorrhage: a potential therapeutic target.

Cerebral vasospasm (VS) is a severe complication of aneurysmal subarachnoid hemorrhage (SAH). Urotensin II (UII) is a potent vasoactive peptide activating the urotensin (UT) receptor, potentially involved in brain vascular pathologies. The authors hypothesized that UII/UT system antagonism with the UT receptor antagonist/biased ligand urantide may be associated with post-SAH VS. The objectives of this study were 2-fold: 1) to leverage an experimental mouse model of SAH with VS in order to study the effect of urotensinergic system antagonism on neurological outcome, and 2) to investigate the association between plasma UII level and symptomatic VS after SAH in human patients. A mouse model of SAH was used to study the impacts of UII and the UT receptor antagonist/biased ligand urantide on VS and neurological outcome. Then a clinical study was conducted in the setting of a neurosurgical intensive care unit. Plasma UII levels were measured in SAH patients daily for 9 days, starting on the 1st day of hospitalization, and were compared with plasma UII levels in healthy volunteers. In the mouse model, urantide prevented VS as well as SAH-related fine motor coordination impairment. Seventeen patients with SAH and external ventricular drainage were included in the clinical study. The median plasma UII level was 43 pg/ml (IQR 14-80 pg/ml). There was no significant variation in the daily median plasma UII level (median value for the 17 patients) from day 0 to day 8. The median level of plasma UII during the 9 first days post-SAH was higher in patients with symptomatic VS than in patients without VS (77 pg/ml [IQR 33.5-111.5 pg/ml] vs 37 pg/ml [IQR 21-46 pg/ml], p < 0.05). Concerning daily measures of plasma UII levels in VS, non-VS patients, and healthy volunteers, we found a significant difference between SAH patients with VS (median 66 pg/ml [IQR 30-110 pg/ml]) and SAH patients without VS (27 pg/ml [IQR 15-46 pg/ml], p < 0.001) but no significant difference between VS patients and healthy volunteers (44 pg/ml [IQR 27-51 pg/ml]) or between non-VS patients and healthy volunteers. The results of this study suggest that UT receptor antagonism with urantide prevents VS and improves neurological outcome after SAH in mice and that an increase in plasma UII is associated with cerebral VS subsequent to SAH in humans. The causality link between circulating UII and VS after SAH remains to be established, but according to our data the UT receptor is a potential therapeutic target in SAH.

Protective Effects of Astragaloside IV on Delayed Cerebral Vasospasm in an Experimental Rat Model of Subarachnoid Hemorrhage

Delayed cerebral vasospasm is an important cause of morbidity and mortality in patients with subarachnoid hemorrhage (SAH). This study aimed to assess the effects of Astragaloside IV (AS-IV) on delayed cerebral vasospasm after SAH. A rat model of SAH was established by puncturing one side of the internal carotid artery. Then, rats received daily intraperitoneal injections of AS-IV (20 mg/kg; SAH-AS-IV group), 0.1% dimethyl sulfoxide (DMSO) (SAH-DMSO group), or saline (SAH group) for 5 days; an additional control group consisted of rats receiving sham surgery and saline injections. Morphologic characteristics of the basilar artery (BA) were measured from histologic sections stained with hematoxylin and eosin and used as indicators of cerebral vasospasm. Immunohistochemistry was used to detect Toll-like receptor-4 (TLR4) and nuclear factor kappa B (NF-κB) p65 protein levels in the BA. Enzyme-linked immunosorbent assay was used to measure the plasma concentrations of tumor necrosis factor-alpha and interleukin-6. Compared with controls, the SAH-DMSO and SAH groups showed increased wall thickness and reduced luminal cross-sectional area (indicative of vasospasm) and increased TLR4 expression and enhanced NF-κB activation in the BA, as well as elevated plasma levels of tumor necrosis factor-alpha and interleukin-6. Administration of AS-IV was associated with significant attenuation of all the aforementioned changes induced by SAH (P < 0.05). AS-IV may attenuate delayed cerebral vasospasm after SAH through inhibition of TLR4/NF-κB-mediated inflammatory signaling pathways.

Fluoxetine is Neuroprotective in Early Brain Injury via its Anti-inflammatory and Anti-apoptotic Effects in a Rat Experimental Subarachnoid Hemorrhage Model.

Fluoxetine, an anti-depressant drug, has recently been shown to provide neuroprotection in central nervous system injury, but its roles in subarachnoid hemorrhage (SAH) remain unclear. In this study, we aimed to evaluate whether fluoxetine attenuates early brain injury (EBI) after SAH. We demonstrated that intraperitoneal injection of fluoxetine (10mg/kg per day) significantly attenuated brain edema and blood-brain barrier (BBB) disruption, microglial activation, and neuronal apoptosis in EBI after experimental SAH, as evidenced by the reduction of brain water content and Evans blue dye extravasation, prevention of disruption of the tight junction proteins zonula occludens-1, claudin-5, and occludin, a decrease of cells staining positive for Iba-1, ED-1, and TUNEL and a decline in IL-1β, IL-6, TNF-α, MDA, 3-nitrotyrosine, and 8-OHDG levels. Moreover, fluoxetine significantly improved the neurological deficits of EBI and long-term sensorimotor behavioral deficits following SAH in a rat model. These results indicated that fluoxetine has a neuroprotective effect after experimental SAH.

Nexilin Regulates Oligodendrocyte Progenitor Cell Migration and Remyelination and Is Negatively Regulated by Protease-Activated Receptor 1/Ras-Proximate-1 Signaling Following Subarachnoid Hemorrhage.

Progressive white matter (WM) impairments caused by subarachnoid hemorrhage (SAH) contribute to cognitive deficits and poor clinical prognoses; however, their pathogenetic mechanisms are poorly understood. We investigated the role of nexilin and oligodendrocyte progenitor cell (OPC)-mediated repair in a mouse model of experimental SAH generated via left endovascular perforation. Nexilin expression was enhanced by the elevated migration of OPCs after SAH. Knocking down nexilin by siRNA reduced OPC migration both in vitro and in vivo and abridged WM repair. In contrast, the protease-activated receptor 1 (PAR1), Ras-proximate-1 (RAP1) and phosphorylated RAP1 (pRAP1) levels in WM were elevated after SAH. The genetic inhibition of PAR1 reduced RAP1 and pRAP1 expression, further enhancing nexilin expression. When delivered at an early stage at a concentration of 25 µg/kg, thrombin receptor antagonist peptide along with PAR1 knockdown rescued the down-regulation of myelin basic protein and improved remyelination at the later stage of SAH. Our results suggest that nexilin is required for OPC migration and remyelination following SAH, as it negatively regulates PAR1/RAP1 signaling, thus providing a promising therapeutic target in WM repair and functional recovery.