Pathogenic mechanisms and therapeutic implications of extracellular matrix remodelling in cerebral vasospasm

Cerebral vasospasm significantly contributes to poor prognosis and mortality in patients with aneurysmal subarachnoid hemorrhage. Current research indicates that the pathological and physiological mechanisms of cerebral vasospasm may be attributed to the exposure of blood vessels to toxic substances, such as oxyhaemoglobin and inflammation factors. These factors disrupt cerebral vascular homeostasis. Vascular homeostasis is maintained by the extracellular matrix (ECM) and related cell surface receptors, such as integrins, characterised by collagen deposition, collagen crosslinking, and elastin degradation within the vascular ECM. It involves interactions between the ECM and smooth muscle cells as well as endothelial cells. Its biological activities are particularly crucial in the context of cerebral vasospasm. Therefore, regulating ECM homeostasis may represent a novel therapeutic target for cerebral vasospasm. This review explores the potential pathogenic mechanisms of cerebral vasospasm and the impacts of ECM protein metabolism on the vascular wall during ECM remodelling. Additionally, we underscore the significance of an ECM protein imbalance, which can lead to increased ECM stiffness and activation of the YAP pathway, resulting in vascular remodelling. Lastly, we discuss future research directions.

2-PMAP Ameliorates Cerebral Vasospasm and Brain Injury after Subarachnoid Hemorrhage by Regulating Neuro-Inflammation in Rats

A subarachnoid hemorrhage (SAH), leading to severe disability and high fatality in survivors, is a devastating disease. Neuro-inflammation, a critical mechanism of cerebral vasospasm and brain injury from SAH, is tightly related to prognoses. Interestingly, studies indicate that 2-[(pyridine-2-ylmethyl)-amino]-phenol (2-PMAP) crosses the blood-brain barrier easily. Here, we investigated whether the vasodilatory and neuroprotective roles of 2-PMAP were observed in SAH rats. Rats were assigned to three groups: sham, SAH and SAH+2-PMAP. SAHs were induced by a cisterna magna injection. In the SAH+2-PMAP group, 5 mg/kg 2-PMAP was injected into the subarachnoid space before SAH induction. The administration of 2-PMAP markedly ameliorated cerebral vasospasm and decreased endothelial apoptosis 48 h after SAH. Meanwhile, 2-PMAP decreased the severity of neurological impairments and neuronal apoptosis after SAH. Furthermore, 2-PMAP decreased the activation of microglia and astrocytes, expressions of TLR-4 and p-NF-κB, inflammatory markers (TNF-α, IL-1β and IL-6) and reactive oxygen species. This study is the first to confirm that 2-PMAP has vasodilatory and neuroprotective effects in a rat model of SAH. Taken together, the experimental results indicate that 2-PMAP treatment attenuates neuro-inflammation, oxidative stress and cerebral vasospasm, in addition to ameliorating neurological deficits, and that these attenuating and ameliorating effects are conferred through the TLR-4/NF-κB pathway.

Analysis of role of rat cerebral pericytes in cerebral vasospasm after subarachnoid hemorrhage and molecular mechanism of neurovascular injury

To investigate mechanism of pericytes in the early stage of subarachnoid haemorrhage (SAH) and its associated microvascular spasm and neurovascular injury, 100 healthy 8-week-old Sprague-Dawley male rats were taken as subjects and divided into four groups: group A (sham operation, control group), group B (SAH operation group), group C (SAH operation group treated with scutellarin), and group D (SAH operation group treated with L-nitro-arginine). 72 hours after the operation, the rats were conducted assessment of neurological impairment, observation of microangiography, detection of blood-brain barrier permeability, observation of skull base haemorrhage, identification of pericyte culture, and measurement of blood nitric oxide. The results showed that neurological impairment score, degree of micro-vasoconstriction, and BBB permeability of group C were significantly better than those of group B and D (P<0.05), there was no significant difference between group C and group A (P>0.05). There were significantly fewer blood clots in the brain of group C, and the order of expression levels of α-smooth muscle actin (α-SMA) in perioperative cells of the four groups from highest to lowest were D, B, C, and A. Nitric oxide concentration inhibited expression of α-SMA in pericytes after SAH at both protein and mRNA levels. The detection results of nitric oxide in the blood of four groups of rats confirmed that pericyte phenotype conversion and actin α-SMA expression could be prevented by upregulation of nitric oxide in serum, so as to relieve pathological symptoms after SAH operation.

Role of Pial Microvasospasms and Leukocyte Plugging for Parenchymal Perfusion after Subarachnoid Hemorrhage Assessed by In Vivo Multi-Photon Microscopy

Subarachnoid hemorrhage (SAH) is associated with acute and delayed cerebral ischemia. We suggested spasms of pial arterioles as a possible mechanism; however, it remained unclear whether and how pial microvasospasms (MVSs) induce cerebral ischemia. Therefore, we used in vivo deep tissue imaging by two-photon microscopy to investigate MVSs together with the intraparenchymal microcirculation in a clinically relevant murine SAH model. Male C57BL/6 mice received a cranial window. Cerebral vessels and leukocytes were labelled with fluorescent dyes and imaged by in vivo two-photon microscopy before and three hours after SAH induced by filament perforation. After SAH, a large clot formed around the perforation site at the skull base, and blood distributed along the perivascular space of the middle cerebral artery up to the cerebral cortex. Comparing the cerebral microvasculature before and after SAH, we identified three different patterns of constrictions: pearl string, global, and bottleneck. At the same time, the volume of perfused intraparenchymal vessels and blood flow velocity in individual arterioles were significantly reduced by more than 60%. Plugging of capillaries by leukocytes was observed but infrequent. The current study demonstrates that perivascular blood is associated with spasms of pial arterioles and that these spasms result in a significant reduction in cortical perfusion after SAH. Thus, the pial microvasospasm seems to be an important mechanism by which blood in the subarachnoid space triggers cerebral ischemia after SAH. Identifying the mechanisms of pial vasospasm may therefore result in novel therapeutic options for SAH patients.

NLRP3 inhibition attenuates early brain injury and delayed cerebral vasospasm after subarachnoid hemorrhage

BACKGROUND

The NLRP3 inflammasome is a critical mediator of several vascular diseases through positive regulation of proinflammatory pathways. In this study, we defined the role of NLRP3 in both the acute and delayed phases following subarachnoid hemorrhage (SAH). SAH is associated with devastating early brain injury (EBI) in the acute phase, and those that survive remain at risk for developing delayed cerebral ischemia (DCI) due to cerebral vasospasm. Current therapies are not effective in preventing the morbidity and mortality associated with EBI and DCI. NLRP3 activation is known to drive IL-1β production and stimulate microglia reactivity, both hallmarks of SAH pathology; thus, we hypothesized that inhibition of NLRP3 could alleviate SAH-induced vascular dysfunction and functional deficits.

METHODS

We studied NLRP3 in an anterior circulation autologous blood injection model of SAH in mice. Mice were randomized to either sham surgery + vehicle, SAH + vehicle, or SAH + MCC950 (a selective NLRP3 inhibitor). The acute phase was studied at 1 day post-SAH and delayed phase at 5 days post-SAH.

RESULTS

NLRP3 inhibition improved outcomes at both 1 and 5 days post-SAH. In the acute (1 day post-SAH) phase, NLRP3 inhibition attenuated cerebral edema, tight junction disruption, microthrombosis, and microglial reactive morphology shift. Further, we observed a decrease in apoptosis of neurons in mice treated with MCC950. NLRP3 inhibition also prevented middle cerebral artery vasospasm in the delayed (5 days post-SAH) phase and blunted SAH-induced sensorimotor deficits.

CONCLUSIONS

We demonstrate a novel association between NLRP3-mediated neuroinflammation and cerebrovascular dysfunction in both the early and delayed phases after SAH. MCC950 and other NLRP3 inhibitors could be promising tools in the development of therapeutics for EBI and DCI.

Valproic Acid Reduces Vasospasm through Modulation of Akt Phosphorylation and Attenuates Neuronal Apoptosis in Subarachnoid Hemorrhage Rats

Aneurysmal subarachnoid hemorrhage (SAH) is a devastating emergent event associated with high mortality and morbidity. Survivors usually experience functional neurological sequelae caused by vasospasm-related delayed ischemia. In this study, male Sprague-Dawley rats were randomly assigned to five groups: sham (non-SAH) group, SAH group, and three groups with SAH treated with different doses of valproic acid (VPA) (10, 20, 40 mg/kg, once-daily, for 7 days). The severity of vasospasm was determined by the ratio of cross-sectional areas to intima-media thickness of the basilar arteries (BA) on the seventh day after SAH. The BA showed decreased expression of phospho-Akt proteins. The dentate gyrus showed increased expression of cleaved caspase-3 and Bax proteins and decreased expression of Bcl-2, phospho-ERK 1/2, phospho-Akt and acetyl-histone H3 proteins. The incidence of SAH-induced vasospasm was significantly lower in the SAH group treated with VPA 40 mg/kg (p < 0.001). Moreover, all groups treated with VPA showed reversal of the above-mentioned protein expression in BA and the dentate gyrus. Treatment with VPA upregulated histone H3 acetylation and conferred anti-vasospastic and neuro-protective effects by enhancing Akt and/or ERK phosphorylation. This study demonstrated that VPA could alleviate delayed cerebral vasospasm induced neuro-apoptosis after SAH.

Changes in the cerebrospinal fluid lipid profile following subarachnoid hemorrhage in a closed cranium model: Correlations to cerebral vasospasm, neuronal cell death and Interleukin-6 synthesis. A pilot study

BACKGROUND

Phospholipids and sphingolipids are cell membrane components, that participate in signaling events and regulate a wide variety of vital cellular processes. Sphingolipids are involved in ischemic stroke pathophysiology. Throughout cleavage of membrane sphingomyelin by sphingomyelinase in stroke patients, it results in increased Ceramide (Cer) levels in brain tissue. Different studies showed the evidence that sphingomyelinase with Cer production induces expression of interleukin (IL)-6 and have vasoconstrictive proprieties. With this study, we intend to evaluate cerebrospinal fluid (CSF) lipid profile changes in a rabbit closed cranium subarachnoid hemorrhage (SAH) model.

METHODS

A total of 14 New Zealand white rabbits were randomly allocated either to SAH or sham group. In the first group SAH was induced by extracranial-intracranial shunting from the subclavian artery into the cisterna magna. Intracranial pressure (ICP) and arterial blood pressure were continuously monitored. Digital subtraction angiography of the basilar artery, CSF and blood samples were performed at day 0 pre SAH and on day 3 post SAH. The amount of IL-6 and various lipids in CSF were quantified using ELISA and Liquid Chromatography-Mass Spectrometry respectively. Cell death was detected in bilateral basal cortex, hippocampus (CA1 and CA3) using terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL).

RESULTS

SAH Induction led to acute increase of ICP and increased delayed cerebral vasospasm (DCVS). At follow up CSF IL-6 levels showed a significant increase compared to baseline. Between baseline and follow up there were no significant differences in any of the measured CSF Lipids irrespective of subgroups. No relevant correlation was found between IL-6 and any of the sphingolipids. We found a correlation between baseline and follow up for the phospholipids phosphatidylethanolamine and phosphatidylcholine.

CONCLUSIONS

Neuronal apoptosis, DCVS and IL-6 seems not to be related to changes in CSF lipid profiles except for PEA and PC in a rabbit closed cranium SAH model.

Targeting High Mobility Group Box 1 in Subarachnoid Hemorrhage: A Systematic Review

Aneurysmal subarachnoid hemorrhage (aSAH) is a complex and potentially deadly disease. Neurosurgical clipping or endovascular coiling can successfully obliterate ruptured aneurysms in almost every case. However, despite successful interventions, the clinical outcomes of aSAH patients are often poor. The reasons for poor outcomes are numerous, including cerebral vasospasm (CVS), post-hemorrhagic hydrocephalus, systemic infections and delayed cerebral ischemia. Although CVS with subsequent cerebral ischemia is one of the main contributors to brain damage after aSAH, little is known about the underlying molecular mechanisms of brain damage. This review emphasizes the importance of pharmacological interventions targeting high mobility group box 1 (HMGB1)-mediated brain damage after subarachnoid hemorrhage (SAH) and CVS. We searched Pubmed, Ovid medline and Scopus for "subarachnoid hemorrhage" in combination with "HMGB1". Based on these criteria, a total of 31 articles were retrieved. After excluding duplicates and selecting the relevant references from the retrieved articles, eight publications were selected for the review of the pharmacological interventions targeting HMGB1 in SAH. Damaged central nervous system cells release damage-associated molecular pattern molecules (DAMPs) that are important for initiating, driving and sustaining the inflammatory response following an aSAH. The discussed evidence suggested that HMGB1, an important DAMP, contributes to brain damage during early brain injury and also to the development of CVS during the late phase. Different pharmacological interventions employing natural compounds with HMGB1-antagonizing activity, antibody targeting of HMGB1 or scavenging HMGB1 by soluble receptors for advanced glycation end products (sRAGE), have been shown to dampen the inflammation mediated brain damage and protect against CVS. The experimental data suggest that HMGB1 inhibition is a promising strategy to reduce aSAH-related brain damage and CVS. Clinical studies are needed to validate these findings that may lead to the development of potential treatment options that are much needed in aSAH.

The Impact of Propolis Factor Caffeic Acid Phenethyl-Ester on the Cerebral Vasospasm and Early Brain Damage in the Experimentally Induced Subarachnoid Hemorrhage on Rats

OBJECTIVE

Caffeic acid phenethyl ester (CAPE), a phenolic compound, besides being 1 of the biologically active components of propolis, is a compound with antioxidant, antiinflammatory, antiviral, reperfusion damage prevention, immune stimulant, and carcinostatic, anticancer properties. The aim of this study was to investigate the possible effects of CAPE on cerebral vasospasm and early brain injury, which were experimentally administered intraperitoneally in rats with subarachnoid hemorrhage.

METHODS

Thirty-two Wistar Albino rats weighing 200 to 300 g were used in our study. The rats divided into 3 groups: the control group (n = 10), subarachnoid hemorrhage group (n = 11), and subarachnoid hemorrhage + CAPE group (n = 11). These groups were evaluated according to the Ischemia index in hippocampal CA3 regions and the morphometric analysis of basilar artery diameter after being sacrificed at the end of 72nd hour.

RESULTS

A significant difference was found between group 1 and group 2 for the CA-3 region, it was concluded that early brain damage occurred after subarachnoid hemorrhage. When the neuronal damage in CA-3 region was evaluated between group 2 and group 3, a statistically significant difference was found between the groups. There was a statistically significant difference between group 1 and group 3 in terms of ischemia detection.

CONCLUSIONS

It was shown that CAPE has a preventive effect on early brain injury after subarachnoid hemorrhage and has a positive effect on reducing cerebral vasospasm. Our study is the first study in the literature showing that CAPE inhibits ischemic brain injury following subarachnoid hemorrhage.

The effects of Cinnamaldehyde on early brain injury and cerebral vasospasm following experimental subarachnoid hemorrhage in rabbits

The neuroprotective and vasodilatory effects of cinnamaldehyde have been widely studied and documented. On the basis of these findings, we hypothesized that cinnamaldehyde exhibits therapeutic effects on subarachnoid hemorrhage-induced early brain injury and cerebral vasospasm. Thirty-two adult male New Zealand white rabbits were randomly divided into four groups of eight rabbits: control, subarachnoid hemorrhage, subarachnoid hemorrhage + vehicle, and subarachnoid hemorrhage + cinnamaldehyde. An intraperitoneal dose of 50 mg/kg cinnamaldehyde was administered 5 min following an intracisternal blood injection, followed by three further daily injections at identical doses. The animals were sacrificed 72 h after subarachnoid hemorrhage was induced. The cross-sectional areas and arterial wall thicknesses of the basilar artery were measured and hippocampal degeneration scores were evaluated. Treatment with cinnamaldehyde was effective in providing neuroprotection and attenuating cerebral vasospasm after subarachnoid hemorrhage in rabbits. It effectively increased the cross-sectional areas of the basilar artery and reduced the arterial wall thickness; in addition, hippocampal degeneration scores were lower in the cinnamaldehyde group. The findings of this study showed, for the first time to our knowledge, that cinnamaldehyde exhibits neuroprotective activity against subarachnoid hemorrhage-induced early brain injury and that it can prevent vasospasm. Potential mechanisms underlying the neuroprotection and vasodilation were discussed. Cinnamaldehyde could play a role in subarachnoid hemorrhage treatment.

Study on the expression and mechanism of inflammatory factors in the brain of rats with cerebral vasospasm

OBJECTIVE

We investigated the significance of IL-1 and ICAM-1 in rat's subarachnoid hemorrhage (SAH) cerebral vasospasm (CVS) model.

MATERIALS AND METHODS

A total of 30 Sprague-Dawley (SD) rats were randomly divided into the SAH group and the Sham group. Cisterna magna auto blood injection was used to prepare the CVS models. We studied and compared changes in the basilar arteries diameters before and after SAH. We measured the cerebrovascular inner diameter before and after SAH modeling using the ultrasound. ELISA method was used to measure the expression of IL-1 and ICAM-1 in peripheral blood. The expression of MAPK and P38 in the brain was tested using Western blot. Brain cells apoptosis was studied using TUNEL method.

RESULTS

Cerebrovascular inner diameter reduced significantly in the SAH group as compared to the control group. The expression of IL-1 and ICAM-1 increased significantly after 48 hours. Compared to the Sham group, p-38 and p-MAPK expression levels in the SAH group increased significantly after 48 hours. Results showed that 48 hours after the operation, the level of apoptosis was significantly higher in the SAH group. IL-1 and ICAM-1 expression levels were associated with a P38-MAPK signal pathway in the brain. p38 and MAPK activation were closely related to apoptosis in the cortex.

CONCLUSIONS

We suggest that the cerebral basilar vasospasm was occurred in rats 48 hours after ASH onset, with an increase in IL-1 and ICAM-1 expression and brain cells apoptosis.

MR-angiography allows defining severity grades of cerebral vasospasm in an experimental double blood injection subarachnoid hemorrhage model in rats

Objective

Magnetic resonance (MR) imaging has been used for the detection of cerebral vasospasm (VSP) related infarction in experimental subarachnoid hemorrhage (eSAH) in rats. Conventional angiography is generally used to visualize VSP, which is an invasive technique with a possible increase in morbidity and mortality. In this study we evaluated the validity of MR-angiography (MRA) in detecting VSP and its feasibility to define VSP severity grades after eSAH in rats.

Methods

SAH was induced using the double-hemorrhage model in 12 rats. In two rats, saline solution was injected instead of blood (sham group). MR was performed on day 1, 2 and on day 5. T1-, T2-, T2*-weighted and time-of-flight MR sequences were applied, which were analyzed by two blinded neuroradiologists. Vessel narrowing of 25–50% was defined as mild, 50–75% as moderate and >75% as severe VSP.

Results

We performed a total of 34 MRAs in 14 rats. In 14 rats, MRA was performed on day 2 and day 5. In six rats MRA was additionally performed on day1 before the blood injection. A good visualization of cerebral vessels was possible in all cases. No VSP was seen in the sham group neither on day 2 nor on day 5. We found vasospasm on day 2 in 7 of the 14 rats (50%) whereas all 7 rats had mild and one rat had additionally moderate and severe vasospasm in one vessel, respectively. On day 5 we found vasospasm in 8 of the 14 rats (60%) whereas 4 rats had severe vasospasm, 1 rat had moderate vasospasm and 3 rats demonstrated mild vasospasm. In 4 of the 14 rats (30%) an ischemic lesion was detected on day 5. Three of these rats had severe vasospasm and one rat had mild vasospasm. Severe vasospasm on day 5 was statistically significant correlated with the occurrence of ischemic lesions (Fisher’s Exact test, OR 19.5, p = 0.03).

Conclusions

MRA is a noninvasive diagnostic tool, which allows a good visualization of the cerebral vasculature and provides reproducible results concerning the detection of VSP and the differentiation into three severity grades in rats. Future studies are needed to directly compare MRA with conventional angiography.

Effects of Cobalt Nitrate on Histopathological and Morphometric Changes in Rat Femoral Artery Vasospasm Model

OBJECTIVE

To determine the effects of cobalt nitrate on the arterial wall in a rat femoral artery vasospasm model.

STUDY DESIGN

Experimental study.

PLACE AND DURATION OF STUDY

Faculty of Medicine, Istanbul University, between November 2009 and September 2010.

METHODOLOGY

Twenty-four rats were separated into three groups named group 1 (n=8, sham-control); group 2 (n=8, vasospasm), and group 3 (n=8, vasospasm + cobalt nitrate treated). Group 3 rats were subjected to intraperitoneal administration of 0.1 mg/kg/day cobalt nitrate for 7 days, followed by histological and morphometric analyses. ANOVAand post hoc analyses were carried out.

RESULTS

The mean vascular wall thickness of the group 1, 2 and 3 rats was found to be 133 ±13, 210 ±15 and 160 ±11 micron, respectively. The mean vascular lumen diameter of the group 1, 2 and 3 rats was 698 ±20, 240 ±15 and 540 ±22 micron, respectively. Arteries in the group 3 had thin smooth endothelium, thin mildly folded internal elastic lamina, and concentric smooth muscle cells. The mean vascular lumen diameter of the group 3 rats showed a significant decrease compared to the group 2 rats.

CONCLUSION

Cobalt nitrate may potentially serve as an agent in preventing cerebral vasospasm after a hemorrhagic episode.

[Recurrent posterior reversible encephalopathy due to vasospasm and cerebral hypoperfusionin in acute leukemia: a case report]

We report the case of a 4-year-old girl who presented with recurrent posterior reversible encephalopathy syndrome (PRES). She was diagnosed with B-precursor acute lymphocytic leukemia (ALL), and was administered remission-induction chemotherapy. On day 28 of the induction therapy, she experienced seizure and prolonged unconsciousness. Blood pressure was slightly elevated. MRI revealed cortical cytotoxic edema in the right temporal and occipital lobes. In the right occipital white matter the lesion with vasogenic edema also existed. Three days later, MRI showed vasogenic edema in subcortical white matter of the right temporal right occipital and bilateral occipital lobes. The lesions had receded with time. Since the seizure occurred, the chemotherapy had been discontinued. The episodes of seizure and prolonged consciousness recurred 22 days later. MRI revealed vasogenic edema in the right occipital lobe, and MR angiography demonstrated vessel irregularity and reduced branch visualization in the middle and posterior cerebral arteries. Arterial spin-labeling (ASL) showed hypoperfusion in both occipital lobes. It suggests that vasoconstriction and hypoperfusion could lead to recurrent PRES in this case. It is possible that ASL might be more sensitive than MRI in detecting the lesions of PRES. It should be noted that PRES might recur in leukemia.

Cerebral vasospasm and corticospinal tract injury induced by a modified rat model of subarachnoid hemorrhage

OBJECTIVE

Double-hemorrhage rat models of subarachnoid hemorrhages (SAH) are most effective at simulating delayed cerebral vasospasms (CVS). The present study modified the models to minimize additional trauma and investigated injury of the corticospinal tract (CST) using diffusion tensor imaging (DTI).

METHODS

On the first day, 0.3ml of autologous arterial blood was collected by puncturing the caudal artery and injected into the cisterna magna via percutaneous puncture; and the operation was repeated on the third day. The diameters of the basilar artery (BA), middle cerebral artery (MCA), and anterior cerebral artery (ACA) were measured by magnetic resonance angiography on days 3, 5, 7, 9, and 11 post-SAH. Meanwhile, on days 3, 7, 11, 15 and 19, DTI was performed to evaluate the injury of the CST at cerebral peduncle (CP) and pyramidal tract (Py) by measuring fractional anisotropy (FA) value.

RESULTS

Blood was deposited mainly in the basal cistern. Diameters of BA, MCA, and ACA were significantly reduced. FA value of the CP was lower in the SAH group than in the control group; but FA value of Py wasn't different between the two groups.

CONCLUSION

This is a minimally-invasive and high performance rat model of SAH. Additionally, the occurrence of CVS is firm and the axons in CP are injured.

Alterations of the thioredoxin system during subarachnoid hemorrhage-induced cerebral vasospasm

BACKGROUND

The exact underlying pathogenic mechanisms and effective preventive or therapeutic interventions for cerebral vasospasm remain obscure. The thioredoxin (Trx) system performs important functions in the central nervous system including neurotrophic and neuroprotective actions. There is no study directly investigating the effects of subarachnoid hemorrhage (SAH) induced cerebral vasospasm on the Trx system in the literature.

METHODS

Sixteen male New Zealand rabbits were randomly divided into two groups of eight rabbits each: a control group and a SAH group. The control group, (n = 8) was a sham surgery group in which SAH was not induced. In the SAH group, (n = 8), the SAH protocol was used to induce cerebral vasospasm. The brain and brainstem were removed and each brainstem was cut coronally into two pieces: an anterior part that contains basilar artery and a dorsal part that contains brainstem tissue. The brainstem tissue thioredoxin-1(Trx1), thioredoxin-2 (Trx2), thioredoxin reductase (TrxR), thioredoxin reductase-1 (TrxR1), thioredoxin-interacting protein (TXNIP) levels were investigated. Total oxidant status (TOS), total antioxidant status (TAS), malondialdehyde levels (MDA) and tumor necrosis factor alpha (TNF-alpha) levels were investigated for determining the oxidative-antioxidative status of the related brain tissues. Basilar artery segments were investigated for cross-sectional area and wall thickness measurements.

RESULTS

SAH statistically significantly reduced the tissue levels of Trx1 (p < 0.01) and TrxR (p < 0.01). Trx2 levels were not significantly altered after SAH (p > 0.05). SAH significantly reduced the expression of TrxR1 (p < 0.01) and significantly increased the expression of TXNIP (p < 0.01) when compared with controls. TOS levels and MDA levels significantly increased after SAH (p < 0.01) and TAS levels significantly reduced after SAH (p < 0.01). TNF-alpha levels significantly increased after SAH (p < 0.01). SAH-induced cerebral vasospasm significantly (p < 0.05) increased the wall thickness and reduced the mean cross-sectional area of the basilar artery (p < 0.05).

CONCLUSIONS

The Trx system seems to be negatively affected by the simultaneously interrelated enzymatic alterations during cerebral vasospasm.

[Content of C-reactive protein in patients in an acute period of a ruptured intracranial aneurysm]

A content of C-reactive protein (CRP) in the blood serum was determined in 36 patients in acute period of a ruptured intracranial arterial aneurysm (AA). It was significantly more, than in a control group, and have exceeded 10 mg/I in 1 - 4th day of the disease. The level of CRP have had differ, depending on severity of cerebral vasospasm (CVS), determined in accordance to the ultrasound investigation data. In a pronounced CVS in majority of patients the level of CRP in the blood serum have had exceed 10 mg/l, and have secured elevated in a spinal liquor on the 7 - 10th day of the disease, differing from this index in patients with moderately pronounced CVS or without it. In patients with severe invalidization or those, who have died, the level of CRP was trust-worthy higher.

The comparative effects of recombinant human erythropoietin and darbepoetin-alpha on cerebral vasospasm following experimental subarachnoid hemorrhage in the rabbit

BACKGROUND

Darbepoetin alpha is a hypersialylated analogue of erythropoietin effective for activating erythropoietin-receptors. This study investigated the vasodilator and neuroprotective effects of darbepoetin alpha on an experimental subarachnoid hemorrhage model and compared it with erythropoietin.

METHODS

Forty adult male New Zealand white rabbits were randomly divided into four groups of ten rabbits each: group 1 (control), group 2 (subarachnoid hemorrhage), group 3 (erythropoietin), and group 4 (darbepoetin alpha). Recombinant human erythropoietin was administered at a dose of 1,000 U/kg intraperitoneally after the induction of subarachnoid hemorrhage and continued every 8 h up to 72 h. Darbepoetin alpha was administered at a single intraperitoneal dose of 30 μg/kg. Animals were killed 72 h after subarachnoid hemorrhage. Basilar artery cross-sectional areas, arterial wall thicknesses, hippocampal degeneration scores and biochemical analyses were measured in all groups.

RESULTS

Both erythropoietin and darbepoetin alpha treatments were found to attenuate cerebral vasospasm and provide neuroprotection after subarachnoid hemorrhage in rabbits. Darbepoetin alpha revealed better morphometric and histopathological results than erythropoietin among experimental subarachnoid hemorrhage-induced vasospasm.

CONCLUSIONS

Our findings, for the first time, showed that darbepoetin alpha can prevent vasospasm and provides neuroprotection following experimental subarachnoid hemorrhage. Moreover, darbepoetin alpha showed better results when compared with erythropoietin.

Effect of melatonin on cerebral vasospasm following experimental subarachnoid hemorrhage

OBJECT

The current study was undertaken to determine whether melatonin therapy reverses vasospasm and prevents apoptosis by inhibiting lipid peroxidation in an experimental subarachnoid hemorrhage (SAH) model.

MATERIALS AND METHODS

The rabbits were divided into four groups as follows: Group 1, SAH + melatonin (5 mg/kg/i.p. BID) simultaneously with SAH (n = 6); Group 2, SAH + melatonin (5 mg/kg/i.p. BID) treated 2 hours after SAH (n = 6); Group 3, control group (n = 4); Group 4, SAH only (n = 6). Light microscopic examinations of the basilar arteries were performed to demonstrate the pathophysiological changes of the arterial wall with hematoxylin- eosin. Apoptosis: Immunohistology using the ApopTag Peroxidase In Situ Apoptosis Detection Kit was used to demonstrate apoptosis in a cross section of basilary arteries. Apoptotic index was calculated as the number of the immunoreactive nuclei per total number of endothelial cells, and expressed as a percentage.

RESULTS

The results of measurements of diameters of the vessels between groups were significantly different (p = 0.028). While basilar arteries of the SAH only group showed 57% constriction, Groups 1 and 2 were calculated as 33 and 26% constriction, respectively, compared with the control group (p < 0.05). And also Groups 1 and 2 showed significant protection of apoptosis compared with Group 4. The difference between the four groups was tested by Kruskal-Wallis test and the significance between the two groups was tested by Mann- Whitney U-test.

CONCLUSION

Melatonin with its strong antioxidant effect can prevent SAH-induced vasospasm and apoptosis of endothelial cells of vessels.

Multidisciplinary treatment of posterior circulation ischemia

Compromise of blood flow to the brain leads to cerebral ischemia, which if left untreated may even result in cerebral infarction. This has been the main cause of major morbidity and mortality over the years in the US and around the world. Cerebral ischemia to the posterior fossa is more critical and difficult to treat. This is primarily due to complex anatomy and physiology of the posterior fossa cerebal circulation. There has been multiple modalities tested over the years to treat posterior fossa ischemia which have definitely contributed in the outcome in patients with this complex problem. Improving the blood flow in the areas of brain at risk in properly selected patients could prevent impending cerebral ischemia and infarction. Today, there are mainly three types of treatment offered to patients with posterior cerebral ischemia. These are (a) medical, (b) endovascular and (c) surgical. The recent advances in technology, the diagnosis and mode of therapy, has definitely improved the outcomes of cerebral ischemia. We discuss the multidisciplinary treatment of posterior circulation ischemia. Various pre-operative and operative techniques involved in treating patients with posterior cerebral ischemia are discussed.

Matricellular protein: a new player in cerebral vasospasm following subarachnoid hemorrhage

INTRODUCTION

Matricellular protein (MCP) is a class of nonstructural and secreted extracellular matrix proteins that exert diverse functions, but its role in vascular smooth muscle contraction has not been investigated.

MATERIAL AND METHODS

First, rat subarachnoid hemorrhage (SAH) models were produced by endovascular perforation and examined for tenascin-C (TNC) and osteopontin (OPN) induction (representatives of MCPs) in vasospastic cerebral arteries using immunostaining. Second, recombinant TNC (r-TNC), recombinant OPN (r-OPN), or both were injected into a cisterna magna in healthy rats, and the effects on the diameter of basilar arteries were determined using India ink angiography.

RESULTS

In SAH rats, TNC immunoreactivity was markedly induced in the smooth muscle cell layers of spastic cerebral arteries on day 1 but not in control animals. The TNC immunoreactivity decreased on day 3 as vasospasm improved: OPN immunoreactivity, on the other hand, was more induced in the arterial wall on day 3. r-TNC injections caused prolonged contractions of rat basilar arteries, which were reversed by r-OPN, although r-OPN itself had no effect on the vessel diameter.

CONCLUSIONS

MCPs, including TNC and OPN, may contribute to the pathophysiology of cerebral vasospasm and provide a novel therapeutic approach against it.

Intra-arterial injection of verapamil in treatment of cerebral vasospasm in a patient with acute subarachnoid hemorrhage from an aneurysm: case report

Cerebral vasospasm is a major cause of cerebral ischemia and neurological deficits in patients after SAH from the aneurysm. According to angiorraphy cerebral vasospasm in acute rupture of an aneurysm is detected in 50-70% of cases, and the risk of ischemia on it's background is 19-46%. One of the new trends of treatment of cerebral vasospasm is the intra-arterial injection of calcium channel blockers. The article presents a case of selective intra-arterial injection of verapamil for the treatment of cerebral vasospasm in patient after severe subarachnoid and parenchymal hemorrhage of the internal carotid artery bifurcation aneurysm with a good clinical outcome.

Targeting C/EBP homologous protein with siRNA attenuates cerebral vasospasm after experimental subarachnoid hemorrhage

Endothelial apoptosis plays a major role in the development of cerebral vascular spasm after subarachnoid hemorrhage (SAH). C/EBP homologous protein (CHOP) orchestrates apoptosis in a variety of cell types in response to endoplasmic reticulum (ER) stress, implicated in the brain injury after SAH. However, the role of CHOP in the mechanism of cerebral vasospasm (CVS) after SAH remains unexplored. The aim of this study was to evaluate the effect of CHOP silencing on endothelial apoptosis and CVS following subarachnoid hemorrhage in the rat. The study was conducted on 65 rats and employed endovascular perforation model of SAH. CHOP siRNAs were injected 24 h prior to the hemorrhage. At 72 h after SAH brains with basilar arteries (BA) were collected from euthanized rats for laboratory investigations. Triple fluorescence stain revealed expression of CHOP in cerebral vascular endothelia after SAH. Marked reduction of CHOP protein and the reduction of its downstream signaling effectors, bim and caspase-3, were found in BA with Western blot analysis. CHOP silencing reduced number of apoptotic endothelial cells in BA, and increased BA diameter after SAH. The amelioration of CVS was associated with reduced neuronal injury in cerebral tissues. In conclusion, CHOP siRNA treatment can effectively combat apoptotic mechanisms of cerebral vasospasm set in motion by subarachnoid bleeding.

[The impact of posterior atlantooccipital membrane on blood flow alterations in Chiari I malformation patients]

Chiari I malformation (CM) is usually associated with CSF flow disturbances at the level of craniovertebral junction. In current literature a few articles aim to demonstrate blood flow disturbances in Chiari I malformation patients. The paper discusses the role of posterior atlantooccipital membrane in vertebrobasilar insufficiency development and presents a case of successful treatment of blood flow alterations after decompression of craniovertebral junction and posterior atlantooccipital membrane resection.

Effect of recombinant streptokinase on the development of chronic cerebral vasospasm after subarachnoid hemorrhage in a swine model

BACKGROUND

After subarachnoid hemorrhage (SAH), the formation of subarachnoid clots and their associated resolution may be involved in the development of chronic cerebral vasospasm. To dissolve and wash out the subarachnoid clot is one of the therapeutic strategies for prevention of cerebral vasospasm.

OBJECTIVE

We investigated the effect of recombinant streptokinase (r-SK), a synthetic plasminogen activator, which is added to degenerate oxyhemoglobin, one of the strongest spasmogenic substances. The efficacy and safety of this therapy concerning the development of chronic cerebral vasospasm were evaluated in a swine model.

METHODS

Eighteen healthy porcine subjects were used. Each was randomly assigned to one of three groups: saline control (A), SAH treated with saline (B), and r-SK injection into the cisterna magna (C). SAH was produced by introduction of blood clots into the cisterna magna on each of 2 days in all subjects in groups B and C. At 24-h post-SAH, a one-time dosage of 15 mg of r-SK was administered to those subjects randomized to group C. Continuous drainage was applied in all three groups. Vessel diameter was evaluated by angiography before the induction of SAH and at day 7 following SAH.

RESULTS

The pre- and post-SAH angiographs of subjects in group A determined no significant difference in mean vessel caliber. In group B, pre- and post-SAH angiography indicated significant (p < 0.05) reductions of the mean vessel caliber of the right internal carotid artery (ICA) and basilar artery (BA) compared with the baseline values before SAH. In the r-SK treated group, the mean percent reduction in vessel caliber of the right ICA and BA on day 7 angiograms showed no significant difference compared with the baseline value before SAH.

CONCLUSIONS

Chronic cerebral vasospasm was inhibited in the animals to whom r-SK was administered for 1 day after double administration of blood clots to the cisterna magna to induce SAH. The results suggest that the post-SAH presence of subarachnoid clots that contain oxyhemoglobin might be involved in the pathogenesis of vasospasm. Further degeneration of these clots by r-SK may have a promising effect for prevention of vasospasm.

6-Mercaptopurine reverses experimental vasospasm and alleviates the production of endothelins in NO-independent mechanism-a laboratory study

INTRODUCTION

Increased endothelin-1 (ET-1) production and diminished nitric oxide synthase (NOS) bioavailability has been observed in aneurysmal subarachnoid hemorrhage (SAH). The authors previously found that 6-mercaptopurine (6-mp) is effective in preventing and reversing arterial narrowing in a rodent SAH model. This present study is of interest to examine the effect of 6-mp on ET-1/endothelial nitric oxide synthase (eNOS) in this animal model.

METHODS

A rodent double hemorrhage SAH model was employed. Animals were randomly assigned to six groups (sham, SAH only, vehicle, 0.5, 1.0 and 2 mg kg(-1) day(-1) 6-mp treatment). Monoclonal CD45 immunostaining was utilized to evaluate monocytes and microglia. The level of pro-inflammatory cytokines, such as IL-1, IL-6 and TNF-α(RT-PCR), and ET-1 (ELISA) was measured. The basilar arteries (BAs) were harvested and sliced, and their cross-sectional areas were determined. Radiolabeled NOS assay kit was applied to detect eNOS.

RESULTS

Morphologically, convolution of internal elastic lamina, endothelial cells distortion, and necrotic smooth muscle were prevalently present in the basilar artery of SAH groups, which was absent in the 1 and 2 mg kg(-1) day(-1) 6-mp plus SAH group or the healthy controls. Significant vasospasm was noted in the vehicle group (lumen patency, 54.6%, p ≤ 0.01 compared with the sham group), but it was less prominent in the 2 mg kg(-1) day(-1) 6-mp treatment group (lumen patency, 87.6%, p < 0.05). In addition, administration with 2 mg kg(-1) day(-1) 6-mp reduced cytokine levels by 11%, 47%, and 34% for IL-1, IL-6, and TNF-α, respectively, and increased ET-1 levels were found in all the animals subject to SAH (SAH only, SAH plus vehicle, SAH plus 0.5 and 1.0 mg kg(-1) day(-1) 6-mp) except in the 2 mg kg(-1) day(-1) 6-mp SAH group, when compared with the healthy controls (no SAH). Meanwhile, treatment with 6-mp did not induce the levels of expressed eNOS in BAs in the 6-mp groups (0.5, 1.0, and 2 mg kg(-1) day(-1) 6-mp plus SAH) when compared with that in the SAH groups (p > 0.1).

CONCLUSION

In summary, treatment with 6-mp decreased the release of pro-inflammatory cytokines and diminished experimental vasospasm. This study offered first evidence that 6-mp dose-dependently reduces the level of ET-1 in a NO-independent mechanism, which corresponds to its antivasospastic effect in the condition of chronic vasospasm.

[Symptomatic vasospasm. Clinical manifestations]

INTRODUCTION

Symptomatic vasospasm in the setting of a subarachnoid hemorrhage is a complication of difficult diagnosis in some clinical situations. Objectives. Describe the clinical characteristics of cerebral vasospasm demonstrated by neurovascular studies in patients with ruptured saccular aneurysm.

PATIENTS AND METHODS

19 consecutive patients with symptomatic vasospasm, evaluated with TCD and any variant of neurovascular study with contrast injection. All these cases were in degrees between 1 and 3 of the World Federation of Neurological Surgeons Scale.

RESULTS

The cognitive and behavioral manifestations were the most frequent (53%), followed by neurological focal deficits (26%). Clinical vasospasm occurred most frequently between day 9 and 10. Vasospasm is predominant in the arteries of the anterior circulation. The high mortality (42%) and the antecedent of arterial hypertension characterized the group with symptomatic vasospasm. There was no statistical relationship between the result of the scale of Fisher and the symptomatic vasospasm. All the TCD parameters had statistical significance.

CONCLUSIONS

The clinical manifestations more frequently associated with symptomatic vasospasm were cognitive and behavioral. This group of patients is characterized by a high mortality. The TCD is a test of great value to predict cerebral ischemia due to vasospasm.

Depletion of Ly6G/C(+) cells ameliorates delayed cerebral vasospasm in subarachnoid hemorrhage

BACKGROUND

The etiology of delayed cerebral vasospasm (DCV) after aneurysmal subarachnoid hemorrhage (SAH) has remained elusive. Growing evidence supports a role for inflammation in the pathogenesis of DCV. We showed that CSF neutrophils predict which patients will develop DCV.

METHODS

We evaluated a murine model of SAH to test the hypothesis that myeloid cells are required for the cerebral damage associated with DCV.

RESULTS

SAH was associated with decreased middle cerebral artery caliber on day 1 which normalized at day 3 and recurred at day 6. In addition, behavioral testing with a Barnes maze showed executive dysfunction that progressively worsened after the seventh day post hemorrhage. To test the role of innate immune responses, we administrated a myeloid cell-depleting monoclonal antibody against Ly6G/C prior to experimental SAH. Myeloid cell depletion ameliorated angiographic vasospasm measured by MCA vessel caliber and normalized behavioral testing.

CONCLUSION

Our findings support the role of Ly6G/C(+) cells in the development of DCV after SAH and suggest that immune modulation of neutrophils or other Ly6G/C(+) cells may be a strategy for the prevention of DCV.

The effect of phosphodiesterase inhibitor tadalafil on vasospasm following subarachnoid hemorrhage in an experimental rabbit model

BACKGROUND

despite the years of study on it, cerebral vasospasm following subarachnoid hemorrhage is still an important cause of mortality and morbidity. The presented study was undertaken to show whether phosphodiesterase inhibitor tadalafil can attenuate the vasospasm process following subarachnoid bleeding.

METHOD

in this study, 20 male New Zealand White rabbits weighing 2,500-3,000 g were randomly assigned to four groups. Animals in group 1 were controls. In group 2, animals were given oral tadalafil at 12, 24 and 36 h and SAH was not induced. SAH induced animals in group 3 did not receive any medication. In group 4, animals received tadalafil at 12, 24 and 36 h after SAH induction. All animals were sacrificed via exsanguination at 48 h after induction of SAH. Brains and brainstems with overlying basilar arteries were removed and stored in fixative at +4°C overnight. Basilar arteries were sectioned from four separate zones, and four sections were obtained from each rabbit. Basilar artery luminal section areas were measured by using SPOT for Windows version 4.1. Statistical comparisons were performed using Kruskal Wallis and ANOVA tests.

FINDINGS

the SAH induced group which had been treated with tadalafil had significantly greater basilar artery luminal area than the untreated group (p < 0.05). There was no significant difference between control group and non-SAH induced group in terms of luminal areas.

CONCLUSION

tadalafil has a potentially preventive effect in treatment of cerebral vasospasm following subarachnoid bleeding.

Early micro vascular changes after subarachnoid hemorrhage

During the last decade much effort has been invested in understanding the events that occur early after SAH. It is now widely accepted that these early events not only participate in the early ischemic injury but also set the stage for the pathogenesis of delayed vasospasm. That early cerebral ischemia occurs after SAH is documented in both experimental SAH and in human autopsy studies; however, angiographic evidence for vasoconstriction early after SAH is lacking and the source of early ischemic injury is therefore unclear. Recently, the cerebral microvasculature has been identified as an early target of SAH. Changes in the anatomical structure of cerebral microvessels, sufficient to cause functional deficits, are found early after experimental SAH. These changes may explain cerebral ischemia in human in the absence of angiographic evidence of large vessel vasoconstriction. This paper summarizes known alterations in cerebral microvasculature during the first 48 h after SAH.

Recurrent ischemic stroke is predicted by intracranial large artery stenosis identified by brain MRA: an observational study of 693 patients from Kaohsiung, Taiwan

PURPOSE

This study aimed to explore the incidence, severity and risk factors of recurrent stroke after stroke stratified by intracranial large artery stenosis (ILAS).

METHODS

This was an observational study of 693 ischemic stroke patients recruited in a medical center in southern Taiwan. ILAS was identified by MRA. Vascular risk factors, therapeutic conditions and stroke severity were evaluated prospectively. Risk of events was estimated by Kaplan-Meier survival analysis and adjusted for sex, age along with all the variables of interest by Cox proportional hazard models.

RESULTS

The mean observation period was 1.1 year with no lost to follow up. There were 57 (8.2%) patients suffered from recurrent ischemic stroke with 6 (10.5%) dead. Recurrent stroke rate was 2.3% within first month after stroke, 1.5% 31-90 days, 3% 91-365 days, and 1.2% within 365-730 days. Annual stroke recurrence was 8.6% (95%CI, 7.7-9.5). History of ischemic stroke (HR 2.793, 1.550-5.043) and ILAS (HR 2.193, 1.197-4.018) were associated with increased risk of recurrence.

CONCLUSION

History of ischemic stroke along with ILAS related to the recurrence. Most of the recurrent stroke was mild in severity. Possibly due to the short interval of observation, recurrent stroke was not related to increased mortality.

Dose-dependent ultrastructural and morphometric alterations after erythropoietin treatment in rat femoral artery vasospasm model

PURPOSE

Cerebral vasospasm is the common cause of poor outcome after aneurysmal subarachnoid hemorrhage (aSAH). Although many agents are experimentally and clinicaly used to protect or recover from vasospasm, an effective neurotherapeutic drug is still missing. Erythropoietin (EPO) is recently a promising candidate. The aim of this study is to investigate the dose-dependent effects of recombinant human EPO (rhEPO) on arterial wall in a rat femoral artery vasospasm model.

METHODS

Thirty two animals were divided into four groups: vasospasm without any treatment (group A), vasospasm +250 IU/kg rhEPO group (group B), vasospasm +500 IU/kg rhEPO group (group C), and control group (group D). Rat femoral artery vasospasm model was used. For groups B and C, 7 days of 250 IU/kg and 500 IU/kg intraperitoneal rhEPO in 0.3 ml saline were administered respectively; and for groups A and D, 0.3 ml saline were administered intraperitoneally without any treatment. After 7 days, histological and morphometric analyses were carried out.

RESULTS

Vasospasm alone group demonstrated the highest vessel wall thicknesses, comparing to other groups (p < 0.001). While for groups B and C, vessel wall thickness values were significantly higher than the control group (p < 0.001), between these two groups, there was no significant difference achieved (p > 0.05).

CONCLUSION

In our study, there was no significant difference between the two rhEPO treatment groups, but rhEPO treatment was shown to be histologically and morphometrically effective in vasospasm. However, if dosage of EPO treatment is augmented, successful results may be achieved.

[Effectiveness of transcranial Doppler ultrasonography for the detection of vasospasm in the anterior cerebral arteries]

INTRODUCTION

The anterior cerebral arteries are often affected by vasospasm secondary to subarachnoid haemorrhage. The effectiveness of transcranial Doppler ultrasonography to detect this complication has still not been accurately determined. AIM. To assess the usefulness of transcranial Doppler ultrasonography for diagnosing vasospasm of the anterior cerebral arteries in patients with subarachnoid haemorrhage.

PATIENTS AND METHODS

We studied 56 patients between the 4th and 14th days of their subarachnoid haemorrhage; all of them were submitted to a contrast-enhanced neurovascular study and daily monitoring with transcranial Doppler ultrasonography. All the patients had a clinical degree of between 1 and 3 on the World Federation of Neurological Surgeons scale, 46 of them had aneurysms, and bleeding was intense in 20 cases (degree 3-4 on the Fisher scale).

RESULTS

The frequency of angiographic vasospasm was 41% in the anterior cerebral arteries. The mean flow velocities in patients with vasospasm were 84.5 cm/s. The maximum peaks of mean blood flow rate were obtained on the tenth day. Sensitivity was 57.9% for flow rates equal to or above 87.5 cm/s, and the predictive positive value was 66.6%. No significant relation was found between the findings of the transcranial Doppler ultrasonography scan, the degree of clinical symptoms and the intensity of bleeding in the computerised axial tomography scan.

CONCLUSIONS

The overall precision of the test was good, the specificity and predictive negative value were excellent, but sensitivity was low.

The effect of the sildenafil citrate on cerebral vasospasm and apoptosis following experimental subarachnoid hemorrhage in rats

AIM

The therapeutic effect of sildenafil citrate on cerebral vasospasm after experimental subarachnoid hemorrhage (SAH) was studied in a rat model.

METHODS

We used four groups of seven rats were as follows: no SAH, no treatment; SAH only; SAH plus 2 days of peroral sildenafil citrate 5mg/kg treatment and SAH plus 2 days of peroral sildenafil citrate 15 mg/kg treatment. Three different parameters were evaluated including the diameter of the basilar artery, the level of lipid peroxidation and the degree of the apoptosis 48 hours following SAH.

RESULTS

The results showed that sildenafil citrate attenuated SAH-induced cerebral vasospasm in the treatment groups in terms of the diameter of the basilar artery and lipid peroxidation in the two treatment groups, but there was no difference in terms of the level of apoptosis.

CONCLUSION

This study indicates that further research on the therapeutic effect of sildenafil citrate can be combined with the use of any apoptosis-blocking agent for the treatment of cerebral vasospasm following experimental subarachnoid hemorrhage.

Activation of nuclear factor-erythroid 2-related factor 2 (Nrf2) in the basilar artery after subarachnoid hemorrhage in rats

Cerebral vasospasm plays a pivotal role in the outcome of patients suffering from subarachnoid hemorrhage (SAH). The mechanisms underlying cerebral vasospasm are complex and interrelated. Previous studies that focused on only one of these mechanisms have proved to be ineffective in clinical practice. Therefore, a therapeutic target is desirable that can interrupt the multi-mechanisms underlying cerebral vasospasm. Nuclear factor-erythroid 2-related factor 2 (Nrf2) has been shown to be a key regulator in reducing oxidative stress, inflammatory damage, and accumulation of toxic metabolites, which are all involved in SAH-induced cerebral vasospasm. However, whether Nrf2 is activated in the cerebral artery after SAH hasn't been studied. In the present study, 30 male rats were randomly divided into two groups: control group (n = 15) and SAH group (n = 15). The animals in the SAH group were subjected to injection of autologous blood into the cisterna magna twice on day 0 and day 2 and were killed on day 5. The cross-sectional area of the basilar artery was measured and the nuclear Nrf2 protein level was studied by Western blot, electrophoretic mobility shift assay (EMSA), and immunohistochemical techniques. The expression of nuclear Nrf2 protein was increased remarkably in the SAH group compared with the control group. Immunohistochemical staining demonstrated that high level expression of Nrf2 was present in endothelial and smooth muscle cells; it was located in both the nuclei and cytoplasm. The results of this study indicate that Nrf2 expression is up-regulated in the cerebral artery of rats after experimental SAH.

Influence of simvastatin on microthrombosis in the brain after subarachnoid hemorrhage in rats: a preliminary study

Although previous studies indicate that simvastatin can attenuate cerebral vasospasm after subarachnoid hemorrhage (SAH), its effect on the secondary pathophysiological changes after SAH has not been investigated. Accumulating evidence demonstrates that SAH-induced microthrombosis plays important roles in the pathogenesis of delayed cerebral ischemia. To date, however, no study focused on the treatment of microthrombosis in SAH models. The purpose of this study was to determine the impact of simvastatin on microthrombi formation after SAH in rats. Adult male SD rats were divided into four groups: (1) control group (n = 6); (2) SAH group (n = 6); (3) SAH+vehicle group (n = 6) and (4) SAH+simvastatin group (n = 6). SAH was induced by injecting 0.3 ml of fresh arterial, non-heparinized blood into the prechiasmatic cistern in 20 sec with a syringe pump. In the SAH+simvastatin group, simvastatin was administered ip at a dose of 20 mg/kg/d after SAH. Brain samples were excised after perfusion fixation at 7 days after SAH. The cross-sectional areas of the middle cerebral artery and anterior cerebral artery were measured. Microclots were evaluated by H&E staining. Microthrombi formation was measured by fibrin(ogen) immunostaining. The results showed that administration of simvastatin prevented vasospasm on day 7 following SAH (p <0.01). The number of microthrombi was significantly increased in both cerebral cortex and cerebellar cortex at 7 days after SAH (p <0.01). Simvastatin treatment down-regulated the formation of microclots in this SAH model and the number of microthombi was decreased significantly in the SAH+simvastatin group compared to the SAH or SAH+vehicle groups (p <0.01). In conclusion, simvastatin administration attenuates cerebral vasospasm and alleviates microthrombosis in the late phase of SAH in this prechiasmatic blood injection model.

Transient symptomatic vasospasm following antero-mesial temporal lobectomy for refractory epilepsy

RATIONALE

Arterial vasospasm has rarely been reported following temporal lobectomy for intractable epilepsy.

CASE PRESENTATION

A 31-year-old patient presented with a global aphasia 2 days after a left dominant anteromesial temporal lobectomy for intractable epilepsy. Magnetic resonance imaging on 5th post-operative day revealed severe narrowing of M1 segment of the left middle cerebral artery (MCA) and Transcranial Doppler (TCD) ultrasonography an increased velocity of the MCA that suggested a severe vasospasm. The patient received continuous intravenous hyperhydratation and nimodipine; aphasia improved within 24 h and resolved completely within 6 weeks, associated with velocity reduction on control TCD.

CONCLUSION

Transient vasospasm is a likely underestimated cause of focal deficit following temporomesial resection that deserves appropriate treatment.

The effects of intravenous cilostazol and nimodipine on cerebral vasospasm after subarachnoid hemorrhage in an experimental rabbit model

AIM

Our aim in this study was to investigate the efficacy of intravenous administration of cilostazol and compare these effects with intravenous usage of nimodipine in subarachnoid hemorrhage model.

MATERIAL AND METHODS

Twenty-five male New Zealand White rabbits were assigned randomly to 1 of 5 groups. Animals in group 1 (n=5) served as controls, group 2 (n=5) was the SAH-only group, group 3 (n=5) was treated with intravenous 10 mg/kg cilostazol, group 4 (n=5) was treated with 0.05 mg/kg intravenous nimodipine, and group 5 (n=5) served as the vehicle group and treated with a mixture of dimethyl sulfoxide and phosphate buffer solution. Basilar arteries were removed from the brain stems and analyzed. The vessels were measured using computer-assisted morphometry (SPOT for Windows Version 4.1). Statistical comparisons were performed using the Kruskall-Wallis and Mann-Whitney U tests.

RESULTS

Basilar artery wall thicknesses in group 3 and 4 were smaller than the group 2 and this was statistically significant at p < 0.05. The mean arterial cross-sectional areas in group 3 and 4 were higher than group 2 and this was also statistically significant at p < 0.05.

CONCLUSION

Our results demonstrate that intravenous administration of both cilostazol and nimodipine significantly attenuates cerebral vasospasm after SAH.

Digoxin may provide protection against vasospasm in subarachnoid haemorrhage

BACKGROUND

Vasospasm is a significant reason for poor clinical outcome in subarachnoid haemorrhage (SAH). One of the possible causes of vasospasm is attributed to the inhibition of Na(+)/K(+)-ATPase and increased intracellular calcium. Although digoxin, a cardiac glycoside (CG), inhibits the Na(+)/K(+)-ATPase, diverse and contradictory biological actions of CGs have also been reported. This study aimed to investigate the effect of digoxin on an experimental vasospasm after subarachnoid haemorrhage (SAH) in rats.

METHODS

The rats used in the study were divided into normal, saline, SAH, and drug groups. A double-haemorrhage method was applied for the SAH groups. Normal saline or blood samples were injected into the cisterna magna. No surgical procedures were performed on the normal group. For the drug groups, daily digoxin was administered intraperitoneally after saline or blood injections. On days 3 and 7 after injections, the brains and basilar artery sections of all the groups were prepared for light-microscopic examination. The wall thickness and luminal area of the basilar artery were calculated by using medical imaging software.

RESULTS

Increased wall thickness and reduced vessel luminal area were conspicuously significant in the SAH groups which did not receive digoxin. In SAH groups after digoxin administration, the vessel wall thickness decreased, and no significant change was found in vessel wall thickness when compared with the normal and saline groups. The vessel luminal area was not reduced in SAH after digoxin administration.

CONCLUSIONS

These results suggest that digoxin administration in experimental SAH may have a beneficial effect on the protection against vasospasm. If further investigations support our results, the present study may offer a new insight into the treatment of SAH.

Anterior circulation mouse model of subarachnoid hemorrhage

A model of subarachnoid hemorrhage (SAH) first described in rats where blood is injected into the prechiasmatic cistern was adapted to mice. The hypothesis was that such an anterior circulation SAH model would produce vasospasm of greater severity and longer duration than other mouse models. The goal was to create a mouse model that could then be used in transgenic and knockout animals in order to further knowledge of SAH and vasospasm. A needle was inserted stereotactically into the prechiasmatic cistern and 100 microl autologous arterial blood injected over seconds (n=10). Effects were compared to injection of saline (n=10) or to sham operation (n=7). Monitoring of cerebral blood flow by laser Doppler showed a statistically similar decrease during injection in both groups. 7 days after SAH there was vasospasm of the middle and anterior cerebral arteries (51% reduction in MCA radius in SAH compared to saline-injected group, P<0.009, Student's t-test). In order to determine if SAH in this model was associated with neuronal injury, brains were examined for TUNEL and fluoro-jade-positive cells. 60% of SAH but not saline-injected mice exhibited TUNEL-positive cells in the cerebral cortex and 30% of the SAH but no saline-injected mice had fluoro-jade positive cells in the cortex, hippocampus and dentate gyrus. The model is simple to perform and may be useful for investigating the pathophysiology of SAH.

Headache and visual symptoms in two patients with MRI alterations in posterior cerebral artery territory

Posterior cerebral artery (PCA) territory infarcts account for only 5-10% of all infarcts in stroke registries. Moreover, the clinical features and etiology of such infarcts have not been studied as extensively as those in other vascular territories.We describe two patients with recurrent episodes of visual symptoms and headache due to probable transitory PCA vasospasm. MR angiography in the acute phase revealed incomplete visualization of PCA, conventional MRI showed mild T2 signal alterations and MR perfusion showed the presence of marked hypoperfusion in the same regions. Diffusion weighted MR images were normal. All these findings resolved after therapy. These cases suggest that reversible signal alterations associated with reversible vessel and perfusion abnormalities may be observed in patients with visual symptoms and headache. Normal DWI-MR may help distinguish these patients from those affected by non-reversible ischemic attacks.

[Effects of human tissue kallikrein on cerebral vasospasm: experiment with rabbits]

OBJECTIVE

To study the effects of human tissue kallikrein (HTK) on symptomatic cerebral vasospasm (CVS) after subarachnoid hemorrhage (SAH).

METHODS

Forty rabbits underwent occlusion of bilateral carotid. Two weeks later the 28 surviving rabbits were randomly divided into to 4 groups: shamed-operation group (n = 8) undergoing injection of normal saline into the cisterna magna on day 1 and day 3, SAH group (n = 6) undergoing injection of nonheparinized autologous arterial blood into the cisterna magna, HTK therapy group (n = 6) undergoing blood injection into the cisterna magna and then injection of HTK via ear marginal vein daily for 3 days, and nimodipine (ND) therapy group (n = 6) undergoing blood injection into the cisterna magna and then injection of ND via ear marginal vein. 3-dimension-CT angiography (3-D CTA) was used to measure the basilar artery diameter on D(0) and D(5). On D(6) the rabbits were killed with their basilar arteries taken out to undergo light microscopic examination.

RESULTS

Blood could be seen in the basis cephalic of the 3 groups undergoing blood injection. 3-D CTA showed that arteriospasm was seen in the SAH and ND groups but not in the HTK group. Microscopy showed obvious pathological changes in basilar artery in the SAH and ND groups but not in the HTK group.

CONCLUSION

HTK given early after SAH effectively alleviates the symptomatic cerebral vasospasm.

The role of nitric oxide in resolution of vasospasam corresponding with cerebral vasospasms after subarachnoid haemorrhage: animal model

Intracranial aneurysmal rupture is the common cause of spontaneous subarachnoid haemorrhage (SAH). This haemorrhage is typically diffuse and located in extracerebral subarachnoid space in which main cerebral arterial branches are situated. The intimate and long-term contact of arterial wall and blood products in the closed space causes the cerebral vasospasm as a serious and frequent complication of SAH. It is connected with significant morbidity and mortality due to developing of focal cerebral ischaemia and subsequently cerebral infarction. The aim of our experimental research was to create the animal model of vasospasm using the femoral artery due to examination of reduced basic dilator activity cause in arterial wall after SAH. The important characteristic of major cerebral arteries is their localization in the closed subarachnoid space which enables their to have long-term contact with blood products after haemorrhage. Thirty six femoral arteries (FA) of eighteen female rats weighing about 300 g were used. In vivo, femoral arteries are microsurgically prepared in both inguinal regions in all rats. Eighteen arteries were encompassed by polytetrafluoroethylene (PTFE) material forming closed tube and autologous blood was injected in the tube around the arterial wall. Additional eighteen arteries, as a control group, were also put in PTFE tube but without exposing to the blood. All rats are left to live for eight days. Afterwards, rats were sacrificed and their arteries were in vitro examined including an isometric tension measurement and histological changes analysis. The tension was measured during application of vasoconstrictors and vasodilatators (nitric oxide, NO). FA exposed to periadventitial blood exhibit hyper reactivity to constrictors (KCl, phenylephrine, acetylcholine) compared to control group. It was also found that NO donor (sodium nitroprusside) diminished arterial spasm induced by blood and vasoconstrictors. In conclusion, FA can be used as a model for vasospasm correlating with cerebral vasospasm after SAH and therefore this model can be utilized in future experiments assessing cerebral vasospasm. The reduced basic dilator activity of spastic femoral artery is caused by an absence of gaseous messenger NO next to the arteries but not by diminished response vasculature to NO. Absence of NO after SAH probably causes the reduced basic dilator activity of cerebral arteries as well. The guanylate-cyclase level in the arterial wall is consequently reduced after SAH primary due to absence of NO but not due to direct reduction of enzyme activities caused by process of blood degradation inside of subarachnoid space.

Loss of CO2-induced distensibility in cerebral arteries with chronic hypertension or vasospasm after subarachnoid hemorrhage

We developed a rat cerebral angiography system using monochromatic synchrotron radiation X-rays at SPring-8, a third generation synchrotron radiation facility. Using new technique, we assessed the distensibility of major trunk arteries after subarachnoid hemorrhage (SAH) in normotensive and hypertensive rats. Twenty-five adult Wistar Kyoto rats (WKY) and fourteen stroke-prone spontaneously hypertensive rats (SHR) were prepared SAH by double hemorrhage injection method into cisterna magna. Angiography was performed on day 7 and was repeated three times in each rat before and after loading of hypercapnia at 100-120 mmHg of PaCO2. The diameters of major trunk vessels were assessed. Light microscopic observation of artery lumen and wall were also performed. Angiographical vasospasm was demonstrated in basilar artery in WKY with 66 % reduction in diameter of control. In ICA and other major trunk in WKY and all the arteries in SHR did not demonstrate vasospasm. SHA resulted in loss of hypercapnia-induced distention in BA of WKY. In SHR, the distensibility was impaired regardless of hemorrhage. Histological study demonstrated basilar artery in WKY thickened at 184 % after SAH and became similar to non-hemorrhagic SHR. ICA in WKY and both BA and ICA in SHR were unchanged in wall thickness before and after SAH. High quality angiography demonstrated deteriorated distensibility in chronic hypertension or SAH-induced spastic vessels.

Inhibition of c-Jun N-terminal kinase pathway attenuates cerebral vasospasm after experimental subarachnoid hemorrhage through the suppression of apoptosis

BACKGROUND

Recent studies have demonstrated that apoptosis in cerebral arteries could play an essential role in cerebral vasospasm after subarachnoid hemorrhage (SAH) and that SP600125, an inhibitor of c-Jun N-terminal kinase (JNK) could suppress apoptosis. The present study examined whether SP600125 could reduce cerebral vasospasm through the suppression of apoptosis.

METHOD

Fifteen dogs were assigned to 3 groups: control, SAH, and SAH + SP600125 (30 micromol/l). SAH was induced by the injection of autologous blood into the cisterna magna on day 0 and day 2. Angiograms were evaluated on day 0 and day 7. The activation of the JNK pathway and caspase-3 were also evaluated using Western blot. To determine the distribution, TUNEL staining and immunohistochemistry for phosphorylated c-jun and cleaved caspase-3 were performed.

FINDINGS

Severe vasospasm was observed in the basilar artery of the SAH dogs. SP600125 reduced angiographic and morphological vasospasm and reduced the expression of cleaved caspase-3, thereby suppressing apoptosis.

CONCLUSIONS

These results demonstrate that SP600125 attenuates cerebral vasospasm through the suppression of apoptosis, which may provide a novel therapeutic target for cerebral vasospasm.