Experimental Subarachnoid Hemorrhage In Rats Research Articles

Investigation of the protective effects of piceatannol on experimental subarachnoid hemorrhage in rats.

Subarachnoid hemorrhage (SAH) is one of the most prevalent brain injuries in humans which has poor prognosis and high mortality rates. Due to several medical or surgical treatment methods, a gold standard method doesn't exist for SAH treatment. Piceatannol (PCN), a natural analog of resveratrol, was reported to reduce inflammation and apoptosis promising a wide range of therapeutic alternatives. In this study, we aimed to investigate the effects of PCN in an experimental SAH model. The alleviating effects of PCN in the hippocampus in an experimental SAH model were investigated for the first time. In this study, 27 Wistar Albino male rats (200-300g; 7-8week) were used. Animals were divided into three groups; SHAM, SAH, and SAH + PCN. SAH model was created with 120µl of autologous arterial tail blood to prechiasmatic cisterna. 30mg/kg PCN was administered intraperitoneally at 1st h after SAH. Neurological evaluation was performed with Garcia's score. RT-PCR was performed for gene expression levels in the hippocampus. Pyknosis, edema, and apoptosis were evaluated by H&E and TUNEL staining. Our results indicated that PCN administration reduced apoptosis (P < 0.01), cellular edema, and pyknosis (P < 0.05) in the hippocampus after SAH. Moreover, PCN treatment significantly decreased the expression levels of TNF-α (P < 0.01), IL-6 (P < 0.05), NF-κB (P < 0.05), and Bax (P < 0.05) in the hippocampus. Our results demonstrated that PCN might be a potential therapeutic adjuvant agent for the treatment of early brain injury (EBI) following SAH. Further studies are required to clarify the underlying mechanisms and treatment options of SAH.

Circadian Rhythm Regulator REV-ERBα Attenuates Neuroapoptosis in Early Brain Injury After Experimental Subarachnoid Hemorrhage in Rats.

Subarachnoid hemorrhage (SAH) is associated with circadian rhythm abnormalities, in which REV-ERBα plays a major regulatory role. Our ambition was to investigate the capacity of REV-ERBα to inhibit neuronal neuroapoptosis induced by early brain injury (EBI) after SAH. The endovascular perforation model was used to produce experimental SAH in Sprague-Dawley rats. Specific small-interfering RNA was used to downregulate the expression REV-ERBα while SR9009 was used to upregulate the expression before assessments. Short- and long-term neurobehavior assessments, immunofluorescence staining, TUNEL staining, Nissl staining, brain water content, and Western blot were performed. The expression level of endogenous REVERBα tended to increase and then decrease after SAH and peaked at 48h. REV-ERBα upregulation diminished neuronal apoptosis and enhanced neurological function deficits. Meanwhile, REV-ERBα downregulation aggravated the damage. Furthermore, the levels of downstream proteins of REV-ERBα (i.e., brain and muscle ARNT-like 1 (BMAL1) and circadian locomotor output cycles kaput (CLOCK)) changed accordingly with REV-ERBα regulation. REV-ERBα may attenuate neuronal apoptosis in EBI after SAH through the BMAL1/CLOCK pathway.

Peroxiredoxin-3 plays a neuroprotective role in early brain injury after experimental subarachnoid hemorrhage in rats

Subarachnoid hemorrhage (SAH), a type of hemorrhagic stroke, is a neurological emergency associated with a high morbidity and mortality rate. After SAH, early brain injury (EBI) is the leading cause of poor prognosis in SAH patients. Peroxiredoxins (PRDXs) are a family of sulphhydryl-dependent peroxidases. Peroxiredoxin-3 (PRDX3) is mainly located in the mitochondria of neurons, which can remove hydrogen peroxide (H2O2); however, the effect of PRDX3 on EBI after SAH remains unclear. In this study, an endovascular perforation model was used to mimic SAH in Sprague Dawley rats in vivo. The results revealed that after SAH, PRDX3 levels decreased in the neurons. PRDX3 overexpression by neuron-specific adeno-associated viruses upregulated PRDX3 levels. Furthermore, PRDX3 overexpression improved long- and short-term behavioral outcomes and alleviated neuronal impairment in rats. Nissl staining revealed that the upregulation of PRDX3 promoted cortical neuron survival. PRDX3 overexpression decreased the H2O2 content and downregulated caspase-9 expression. In conclusion, PRDX3 participates in neuronal protection by inhibiting the neuronal mitochondria-mediated death pathway; PRDX3 may be an important target for EBI intervention after SAH.

TREM2 modulates neuroinflammation with elevated IRAK3 expression and plays a neuroprotective role after experimental SAH in rats

BackgroundThe modulation of neuroinflammation is a new direction that may alleviate the early brain injury after subarachnoid hemorrhage (SAH). Brain resident microglia/macrophages (Mi/MΦ) are the key drivers of neuroinflammation. Triggering receptor expressed on myeloid cells 2 (TREM2) has been reported to play a neuroprotective role by activating phagocytosis and suspending inflammatory response in experimental ischemic stroke and intracerebral hemorrhage. This study was designed to investigate the role of TREM2 on neuroinflammation and neuroprotective effects in a rat SAH model. MethodsAdult male Sprague-Dawley rats were induced SAH through endovascular perforation. Lentivirus vectors were administered by i.c.v. to induce TREM2 overexpression or knockdown 7 days before SAH induction. Short- and long-term neurobehavioral tests, western blotting, immunofluorescence, enzyme-linked immunosorbent assay, terminal deoxynucleotidyl transferase dUTP nick end labeling and Nissl staining were performed to explore the neuroprotective role of TREM2 after SAH. ResultsThe expression of TREM2 elevated in a rat SAH model with a peak at 48 h after SAH and mainly expressed in Mi/MΦ in brain. TREM2 overexpression improved short- and long-term neurological deficits induced by SAH in rats, while TREM2 knockdown worsened neurological dysfunction. The rats with TREM2 overexpressed presented less neuronal apoptosis and more neuronal survival at 48 h after SAH, while the rats with TREM2 knockdown presented on the contrary. TREM2 overexpression manifested activated phagocytosis and suppressed inflammatory response, with the increase of CD206+/CD11b+ cells and IL-10 expression as well as the decrease of the infiltration of MPO+ cells and the expression of TNF-α, IL-1β. While TREM2 knockdown abolished these effects. The protein level of IRAK3, a negative regulatory factor of inflammation, was significantly elevated after TREM2 overexpression and declined after TREM2 knockdown. ConclusionsOur research suggested TREM2 played a neuroprotective role and improved the short- and long-term neurological deficits by modulating neuroinflammation after SAH. The modulation on neuroinflammation of TREM2 after SAH was related with the elevated protein level of IRAK3.

Thioredoxin 1 regulates the pentose phosphate pathway via ATM phosphorylation after experimental subarachnoid hemorrhage in rats

Subarachnoid hemorrhage (SAH), a type of hemorrhagic stroke, is a neurological emergency with high morbidity and mortality. Early brain injury (EBI) after SAH is the leading cause of poor prognosis in SAH patients. TRX system is a NADPH-dependent antioxidant system which is composed of thioredoxin reductase (TRXR), thioredoxin (TRX). The pentose phosphate pathway (PPP), a pathway through which glucose can be metabolized, is a major source of NADPH. Thioredoxin 1 (TRX1) is a member of thioredoxin system mainly located in cytoplasm. Serine/threonine kinases ataxia telangiectasia mutated (ATM) is an important oxidative stress receptor, and TRX1 can regulate ATM phosphorylation and then affect the activity of PPP key enzyme glucose 6-phosphate dehydrogenase (G6PD). However, whether TRX1 is involved in the regulation of PPP pathway after subarachnoid hemorrhage remains unclear. The results showed that after SAH, the level of TRX1 and phosphor-ATM decreased while the level of TRXR1 increased. G6PD protein level remained unchanged but the activity decreased, and the NADPH contents decreased. Overexpression of TRX1 by lentivirus upregulates the level of phosphor-ATM, G6PD activity and NADPH content. TRX1 overexpression improved short-term and long-term neurobehavioral outcomes and alleviated neuronal impairment in rats. Nissl staining showed that upregulation of TRX1 reduced cortical neuron injury. Our study shows that TRX1 participates in the PPP pathway by regulating phosphorylation ATM, which is accomplished by affecting G6PD activity. TRX1 may be an important target for EBI intervention after SAH.

Loss of monocarboxylate transporter 1 aggravates white matter injury after experimental subarachnoid hemorrhage in rats.

Monocarboxylic acid transporter 1 (MCT1) maintains axonal function by transferring lactic acid from oligodendrocytes to axons. Subarachnoid hemorrhage (SAH) induces white matter injury, but the involvement of MCT1 is unclear. In this study, the SAH model of adult male Sprague-Dawley rats was used to explore the role of MCT1 in white matter injury after SAH. At 48 h after SAH, oligodendrocyte MCT1 was significantly reduced, and the exogenous overexpression of MCT1 significantly improved white matter integrity and long-term cognitive function. Motor training after SAH significantly increased the number of ITPR2+SOX10+ oligodendrocytes and upregulated the level of MCT1, which was positively correlated with the behavioral ability of rats. In addition, miR-29b and miR-124 levels were significantly increased in SAH rats compared with non-SAH rats. Further intervention experiments showed that miR-29b and miR-124 could negatively regulate the level of MCT1. This study confirmed that the loss of MCT1 may be one of the mechanisms of white matter damage after SAH and may be caused by the negative regulation of miR-29b and miR-124. MCT1 may be involved in the neurological improvement of rehabilitation training after SAH.

Hydrogen gas post-conditioning alleviates cognitive dysfunction and anxiety-like behavior in a rat model of subarachnoid hemorrhage.

Subarachnoid hemorrhage (SAH) results in high rates of mortality and lasting disability. Hydrogen gas (H2) is an antioxidant with demonstrated neuroprotective efficacy. The present study examined the therapeutic efficacy of H2 inhalation on early brain injury following experimental SAH in rats and the potential underlying molecular mechanisms. The rats were randomly separated into three groups (n=36 per group): Sham, SAH and SAH + H2. Endovascular perforation of the right internal carotid artery was used to establish SAH. After perforation, rats in the SAH + H2 group inhaled 2.9% H2 with regular oxygen for 2 h. Then, 24 h post-SAH, TUNEL staining was used to detect apoptotic neurons, and both immunostaining and western blotting were conducted to examine changes in p38 MAPK activity and the expression levels of apoptotic regulators (Bcl-2, Bax and cleaved caspase-3) in the ventromedial prefrontal cortex. Then, 30 day post-SAH, Nissl staining was performed to detect neuronal injury, brain MRI was conducted to detect gross changes in brain structure and metabolism, the open field test was used to assess anxiety and the novel object recognition test was performed to assess memory. H2 inhalation following experimental SAH stabilized brain metabolites, improved recognition memory and reduced anxiety-like behavior, the neuronal apoptosis rate, phosphorylated p38 MAPK expression, cleaved caspase-3 expression and the Bax/Bcl-2 ratio. Collectively, the present results suggested that H2 inhalation can alleviate SAH-induced cognitive impairment, behavioral abnormalities and neuronal apoptosis in rats, possibly via inhibition of the p38 MAPK signal pathway.

Hydrocephalus Following Experimental Subarachnoid Hemorrhage in Rats with Different Aerobic Capacity.

Low aerobic capacity is considered to be a risk factor for stroke, while the mechanisms underlying the phenomenon are still unclear. The current study looked into the impacts of different aerobic capacities on early brain injury in a subarachnoid hemorrhage (SAH) model using rats bred for high and low aerobic capacity (high-capacity runners, HCR; low-capacity runners, LCR). SAH was modeled with endovascular perforation in HCR and LCR rats. Twenty-four hours after SAH, the rats underwent behavioral testing and MRI, and were then euthanized. The brains were used to investigate ventricular wall damage, blood–brain barrier breakdown, oxidative stress, and hemoglobin scavenging. The LCR rats had worse SAH grades (p < 0.01), ventricular dilatation (p < 0.01), ventricular wall damage (p < 0.01), and behavioral scores (p < 0.01). The periventricular expression of HO-1 and CD163 was significantly increased in LCR rats (p < 0.01 each). CD163-positive cells were co-localized with HO-1-positive cells. The LCR rats had greater early brain injuries than HCR rats. The LCR rats had more serious SAH and extensive ventricular wall damage that evolved more frequently into hydrocephalus. This may reflect changes in iron handling and neuroinflammation.

Sleep deprivation aggravates brain injury after experimental subarachnoid hemorrhage via TLR4-MyD88 pathway.

Subarachnoid hemorrhage (SAH) is a life-threatening cerebrovascular disease, and most of the SAH patients experience sleep deprivation during their hospital stay. It is well-known that sleep deprivation is one of the key components of developing several neurological disorders, but its effect on brain damage after SAH has not been determined. Therefore, this study was designed to evaluate the effect of sleep deprivation using an experimental SAH model in rats. Induction of sleep deprivation for 24 h aggravated the SAH-induced brain damage, as evidenced by brain edema, neuronal apoptosis and activation of caspase-3. Sleep deprivation also worsened the neurological impairment and cognitive deficits after SAH. The results of immunostaining and western blot showed that sleep deprivation increased the activation of microglial cells. In addition, sleep deprivation differently regulated the expression of anti-inflammatory and pro-inflammatory cytokines. The results of immunofluorescence staining and western blot showed that sleep deprivation markedly increased the activation of Toll-like receptor 4 (TLR4) and myeloid differentiation primary response protein 88 (MyD88). Mechanically, treatment with the TLR4 inhibitor TAK-242 or the MyD88 inhibitor ST2825 significantly attenuated the brain damage and neuroinflammation induced by sleep deprivation after SAH. In conclusion, our results indicate that sleep deprivation aggravates brain damage and neurological dysfunction following experimental SAH in rats. These effects were mediated by the activation of the TLR4-MyD88 cascades and regulation of neuroinflammation.

Intra-arterial Contrast-enhanced Micro-computed Tomography Can Evaluate Intracranial Status in the Ultra-early Phase of Experimental Subarachnoid Hemorrhage in Rats

The endovascular perforation (EP) model is a common technique for experimental subarachnoid hemorrhage (SAH) in rats, simulating the pathophysiological features observed in the acute phase of SAH. Due to the drawbacks of large variations in the amount of bleeding, the results obtained from this model require severity evaluation. However, no less-invasive procedure could confirm the precise intracranial conditions immediately after establishing the rat EP model. We created a novel method for evaluating SAH immediately after establishing the rat EP model using intra-arterial contrast-enhanced micro-computed tomography (CT). We administered contrast agents continuously via the carotid artery during surgery and performed CT examination immediately after SAH induction. First, bleeding severity was classified by establishing a scoring system based on the CT findings (cSAH scoring system). Subsequently, we determined the actual SAH distribution macroscopically and histologically and compared it with the cSAH scores. Second, we investigated the contrast agent’s neurotoxicity in rats. Finally, we confirmed the correlation between cSAH scores and SAH severity, including neurological status, cerebral vasospasm, and hematoma volume 24 hr after SAH. Intra-arterial contrast-enhanced micro-CT could visualize the distribution of SAH proportionally to the bleeding severity immediately after establishing the EP model. Moreover, the contrast agent administration was determined not to be neurotoxic to rats. The cSAH scoring revealed a significant correlation with the SAH severity in the rat EP model (P <0.01). Thus, our minimally invasive method provided precise information on intracranial status in the ultra-early phase of SAH in rats EP model.

Eucalyptol ameliorates early brain injury after subarachnoid haemorrhage via antioxidant and anti-inflammatory effects in a rat model

Context As the terpenoid oxide extracted from Eucalyptus L. Herit (Myrtaceae), eucalyptol (EUC) has anti-inflammatory and antioxidant effects. Objective To evaluate the neuroprotective role of EUC in subarachnoid haemorrhage (SAH). Materials and methods Sprague-Dawley rats were divided into 4 groups: sham group, SAH group, SAH + vehicle group, and SAH + EUC group. SAH was induced by endovascular perforation. In SAH + EUC group, 100 mg/kg EUC was administrated intraperitoneally at 1 h before SAH and 30 min after SAH, respectively. Neurological deficits were examined by modified Neurological Severity Scores (mNSS). The brain edoema was evaluated by wet-dry method. Neuronal apoptosis was detected by Nissl staining. The expression of Bcl-2, cleaved caspase-3, phospho-NF-κB p65, ionised calcium-binding adapter molecule-1 (Iba-1), nuclear factor erythroid-2 (Nrf-2), and haem oxygenase 1 (HO-1) were measured by Western blot. Expression of pro-inflammatory cytokines was detected by qRT-PCR. Oxidative stress markers were also measured. Results EUC markedly relieved brain edoema (from 81.22% to 78.33%) and neurological deficits [from 16.28 to 9.28 (24 h); from 12.50 to 7.58 (48 h)]. EUC reduced neuronal apoptosis, microglial activation, and oxidative stress. EUC increased the expression of HO-1 (1.15-fold), Nrf2 (1.34-fold) and Bcl-2 (1.17-fold) in the rats’ brain tissue, and down-regulated the expressions of cleaved caspase-3 (41.09%), phospho-NF-κB p65 (14.38%) and pro-inflammatory cytokines [TNF-α (34.33%), IL-1β (50.40%) and IL-6 (59.13%)]. Discussion and Conclusion For the first time, this study confirms that EUC has neuroprotective effects against early brain injury after experimental SAH in rats.

Neuroprotective effects of quercetin on cerebral vasospasm following experimental subarachnoid haemorrhage in rats

Background/aim We examined the protective effects of the natural flavonoid, quercetin, against cerebral vasospasm in an experimental rat subarachnoid haemorrhage (SAH) model. Materials and methods Thirty-eight albino Wistar rats were divided into five groups as follows: group 1 (G1, n=8), no experimental intervention; group 2 (G2, n=8), subarachnoid physiological saline; group 3 (G3, n=8), SAH; group 4 (G4, n=7) SAH and low-dose (10 mg/kg) quercetin treatment; group 5 (G5, n=7), SAH and high-dose (50 mg/kg) quercetin treatment. Subarachnoid haemorrhage was induced by injection of 0.15 cc of autologous blood taken from the tail artery into the cisterna magna from the craniocervical junction and basilar arteries and blood samples were taken for biochemical and histopathological analyses. Results Malondialdehyde (MDA) levels were significantly higher in G2 and G3 than in G1 (P < 0.05). Significant decreases in MDA were observed in G4 and G5 compared with G2 (P < 0.05, G4–G2; P < 0.05, G5–G2). There were no significant differences between G2 and G3 or among G1, G4, and G5. No statistically significant differences were found in total antioxidant capacity between the groups (P > 0.05). There were no significant differences in basilar artery (BA) wall thickness between G3 and G4 or between G3 and G5, but G4 and G5 showed greater luminal diameters than G3 (P < 0.05). There were no significant differences in BA thickness or luminal diameter between G4 and G5. Conclusion Our results suggested that quercetin may be beneficial in SAH therapy by preventing vasospasm.

Nix Plays a Neuroprotective Role in Early Brain Injury After Experimental Subarachnoid Hemorrhage in Rats.

Nix is located in the outer membrane of mitochondria, mediates mitochondrial fission and implicated in many neurological diseases. However, the association between Nix and subarachnoid hemorrhage (SAH) has not previously been reported. Therefore, the present study was designed to evaluate the expression of Nix and its role in early brain injury (EBI) after SAH. Adult male Sprague-Dawley (SD) rats were randomly assigned to various time points for investigation after SAH. A rat model of SAH was induced by injecting 0.3 ml of autologous non-heparinized arterial blood into the prechiasmatic cistern. The expression of Nix was investigated by Western blot and immunohistochemistry. Next, Nix-specific overexpression plasmids and small interfering RNAs (siRNAs) were separately administered. Western blot, neurological scoring, Morris water maze, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining and fluoro-jade B (FJB) staining were performed to evaluate the role of Nix in EBI following SAH. We found that Nix was expressed in neurons and its expression level in the SAH groups was higher than that in the Sham group, which peaked at 24 h after SAH. Overexpression of Nix following SAH significantly decreased the expression of translocase of outer mitochondrial membrane 20 (TOMM20, a marker of mitochondria), ameliorated neurological/cognitive deficits induced by SAH, and reduced the total number of apoptotic/neurodegenerative cells, whereas siRNA knockdown of Nix yielded opposite effects. Taken together, our findings demonstrated that the expression of Nix is increased in neurons after experimental SAH in rats, and may play a neuroprotective role in EBI following SAH.

Cervical sympathectomy modulates the neurogenic inflammatory neuropeptides following experimental subarachnoid hemorrhage in rats

BackgroundNeuroinflammation is implicated in cerebral vasospasm and brain injuries after subarachnoid hemorrhage (SAH). In addition to classical neuroinflammation with increased inflammatory cytokines, a sterile neurogenic inflammation characterized by release of potent vasoactive neuropeptides may be responsible for brain injuries after SAH. Sympathetic discharges from superior cervical ganglion contribute to vasoconstriction of cerebral arteries Thus, we investigated the effects of surgical cervical sympathectomy on the neurogenic inflammatory neuropeptides shortly after SAH induction in a model of SAH in rats. MethodsMale Wistar rats were divided into 4 groups: control; was not touched, saline group; 300 μl of saline was injected into prechiasmatic cistern, SAH+Sham group; 300 μl of autologous blood was injected to induce subarachnoid hemorrhage into prechiasmatic cistern; SAH+Symp group; the left cervical sympathetic branch was surgically removed after the induction of SAH. Levels of neuropeptides CGRP, SP and VIP which are responsible for neurogenic inflammation, in plasma, trigeminal ganglion, brainstem and brain tissue were measured by ELISA. In addition, c-fos expression as a marker of neuronal activation in the trigeminal nucleus caudalis (TNC) was determined by immunohistochemical staining. ResultsSAH significantly increased c-fos expression in the TNC, as well as CGRP, SP and VIP concentrations in plasma and trigeminal ganglion neurons, and also CGRP and SP concentrations in the brainstem. Cervical sympathectomy application significantly reduced the increases in these parameters induced by SAH. ConclusionsOur findings suggest that cervical sympathectomy treatment may prevent early brain injury by modulating SAH-induced neurogenic inflammatory neuropeptides such as CGRP, SP and VIP, and improve the quality of life in survivors following SAH.

Initiating TrkB/Akt Signaling Cascade Preserves Blood–Brain Barrier after Subarachnoid Hemorrhage in Rats

The integrity of the blood–brain barrier (BBB) plays a vital role in affecting the prognosis of subarachnoid hemorrhage (SAH). This study aimed to investigate activation of the Tropomyosin-related kinase receptor B (TrkB) and its downstream signaling pathway on preserving BBB breakdown after experimental SAH. An endovascular perforation SAH model was applied. N-[2-(5-hydroxy-1H-indol-3-yl) ethyl]-2- oxopiperidine-3-carboxamide (HIOC), the derivative of N-acetyl serotonin (NAS), was intracerebroventricularly administered 3 h after SAH induction. The neurologic scores and brain water content were evaluated in an outcome study. Western blot and immunofluorescence staining were used to investigate the mechanism. The results indicated that HIOC activated the TrkB/Akt pathway, increased the tight junction expression, improved neurologic deficits, and ameliorated brain edema after SAH. Thus, we conclude that initiating the TrkB/Akt signaling cascade preserves BBB breakdown after experimental SAH in rats.

The Role of Intracranial Pressure and Subarachnoid Blood Clots in Early Brain Injury After Experimental Subarachnoid Hemorrhage in Rats

Early brain injury after subarachnoid hemorrhage (SAH), which is considered a main factor leading to poor outcome, is believed to be caused by the increase of intracranial pressure (ICP) and/or the presence of subarachnoid blood clots (SBC) itself. The purpose of this study was to examine whether ICP or SBC is more important to neurologic deficit in the presence of apoptosis or edema. A total of 50 rats were allocated to 3 groups: an endovascular perforation SAH model (the SAH group), a cisterna magna saline injection model (the saline injection group), and a cisterna magna sham injection model (the sham injection group). Statistical analysis of correlations among the ICP, the grade of clot volume, neuronal apoptosis, brain water content (brain edema), and neurologic deficit was performed. In the SAH group, each of increased ICP and clot volume was correlated with neuronal apoptosis and brain edema. In the saline injection group, increased ICP was associated with apoptosis, but it did not correlate with brain edema. Neuronal apoptosis (r= 0.75; P < 0.01) and brain edema (r= 0.89; P < 0.01) correlated independently with neurologic deficit in the SAH group. The present study suggests that neuronal apoptosis is caused mainly by increased ICP, whereas brain edema is induced by SBC, and increased ICP could aggravate it in the presence of SBC. Brain edema could affect neurologic deficit, but apoptosis alone may be less influential. Not only ICP but also SBC seem important for brain damage in the acute stage of SAH.

RIP3 participates in early brain injury after experimental subarachnoid hemorrhage in rats by inducing necroptosis

Necroptosis is a regulated form of necrosis that is mediated by a variety of proteins including tumor necrosis factor-α (TNF-α) and receptor-interacting proteins (RIPs). TNF-α, a critical inflammatory molecule, is one of the initiating signals in the necroptosis pathway, and RIP3 acts as a switch that commits the cell to necroptosis. Subarachnoid hemorrhage (SAH) is a common type of hemorrhagic stroke with high mortality and disability rates. RIP3 has been studied in many central nervous system (CNS) diseases, but its role in SAH has not been investigated in depth. Here, we used an autologous-blood injection model to study the role of RIP3 in brain injury induced by SAH in rats. Several indexes such as brain edema, loss of blood-brain barrier (BBB) integrity, and behavioral tests of neurological function were used to evaluate brain damage in SAH-injured rats. We found that the expression of RIP3 was increased in the rat brain after SAH, reaching the highest point 24 h post-injury. We also showed that genetic or pharmacological inhibition of RIP3 or TNF-α reduced the brain damage induced by SAH, whereas overexpression of RIP3 aggravated brain injury and neurological damage. Additionally, we verified the presence of RIP3-mediated necroptosis in an in vitro SAH model of primary cultured neurons treated with conditioned medium from primary microglia activated by oxygen hemoglobin (OxyHb). Collectively, our findings indicated that RIP3 contributed to brain damage after SAH by inducing necroptosis.

Effects of 2-Aminoethyl Diphenylborinate, a Modulator of Transient Receptor Potential and Orai Channels in Subarachnoid Hemorrhage: An Experimental Study

Cerebral vasospasm remains a serious problem affecting morbidity and mortality in patients with subarachnoid hemorrhage (SAH) during neurosurgery. We aimed to demonstrate the role of the transient receptor potential channel and other channels for Ca2+ in the etiology of cerebral vasospasm using 2-aminoethyl diphenylborinate (2-APB) and the effective dose range of an unstudied pharmacological agent, which can limit vasospasm. We performed an experimental study using 32 Sprague-Dawley rats divided into 4 groups: sham group (n=8), SAH group (n= 8), 2-APB group (SAH rats intraperitoneally administered with 0.5 mg/kg 2-APB; n= 8), and 2-APB-2 group (SAH rats intraperitoneally administered with 2 mg/kg 2-APB; n= 8). The rats were sacrificed after 24 hours, and superoxide dismutase, glutathione peroxidase, malondialdehyde, tumor necrosis factor-α, and interleukin-1β in the brain tissue and serum were measured. The histopathological investigation of brain tissue included measurement of the luminal diameter and wall thickness of the basilar artery (BA), and apoptotic cells in the hippocampus were counted after caspase staining. Autologous arterial blood injection into the cisterna magna caused vasospasm in rats. 2-APB treatment increased the BA wall thickness and reduced the BA lumen diameter, inducing significant vascular changes. 2-APB also alleviated cell apoptosis at 24 hours after SAH. In experimental SAH in rats, 2-APB treatment increased the BA wall thickness and reduced the BA lumen diameter, inducing significant vascular changes. 2-APB also alleviated cell apoptosis at 24 hours after SAH.

Allicin attenuates early brain injury after experimental subarachnoid hemorrhage in rats

Early Brain Injury, rather than Cerebral Vasospasm, has been demonstrated to be more important for patients with Subarachnoid hemorrhage. It is considered that allicin can make sense in a wide range of pharmacological areas and can be taken as a therapeutic method in many pathologic situations. We have explored the potential effect of allicin and possible mechanisms in Early Brain Injury after Experimental Subarachnoid Hemorrhage in Rats. With therapy (70 mg/kg Allicin, rather than 30 mg/kg) 30 min post SAH, groups showed better neurological scores in 24 h. Significant differences could be found in body weight ratio between the SAH + vehicle groups and SAH + Allicin groups. Treatment with 70 mg/kg, not 30 mg/kg, Allicin significantly reduced brain edema and EB extravasation in 24 h after SAH. Assessments in 24 h after SAH showed that treatment with 70 mg/kg Allicin in 30 min after SAH significantly restrained the expression of cleaved caspase-3, mitigated the severity of neuronal degeneration, decreased the proportion of apoptotic neurons and the elevated MDA levels, and increased the suppressed GSH and SOD levels. We demonstrated for the first time that Allicin extenuated brain edema and blood-brain barrier dysfunction, improved neurological outcomes by the suppression of apoptosis and oxidative stress damage after SAH in experimental models, which may shade new light on the treatments of SAH.

MCC950 attenuated early brain injury by suppressing NLRP3 inflammasome after experimental SAH in rats

Nucleotide oligomerization domain(NOD)-like receptor protein-3(NLRP3) inflammasome is a multiprotein complex, which results in the inflammatory response in early brain injury(EBI) after subarachnoid hemorrhage(SAH). MCC950, a specific NLRP3 inhibitor, plays neuroprotective effects in several central nervous system diseases. However, the role of MCC950 in SAH remains elusive. This study aims to investigate whether MCC950 exerts neuroprotection after experimental SAH and further explore the potential mechanisms. The SAH model was induced by endovascular perforation process using adult male Sprague-Dawley rats. MCC950 was injected intraperitoneally 1 h after SAH with a dose of 10 mg/kg. The results showed that MCC950 significantly ameliorated severe brain edema and neurological dysfunction. Furthermore, MCC950 efficiently reduced NLRP3 inflammasome expression as well as the pro-inflammatory cytokines, such as TNF-α, IL-1ß, and IL-6. In addition, the protective effect of MCC950 was blunted by lipopolysaccharide. In conclusion, our findings suggest that MCC950 alleviated SAH-induced EBI by suppressing inflammation.