Effects of mitogen-activated protein kinase inhibitors on cerebral vasospasm in a double-hemorrhage model in dogs

Identification of mitophagy and ferroptosis-related hub genes associated with intracerebral haemorrhage through bioinformatics analysis

BACKGROUND

Mitophagy and ferroptosis occur in intracerebral haemorrhage (ICH) but our understanding of mitophagy and ferroptosis-related genes remains incomplete.

AIM

This study aims to identify shared ICH genes for both processes.

METHODS

ICH differentially expressed mitophagy and ferroptosis-related genes (DEMFRGs) were sourced from the GEO database and literature. Enrichment analysis elucidated functions. Hub genes were selected via STRING, MCODE, and MCC algorithms in Cytoscape. miRNAs targeting hubs were predicted using miRWalk 3.0, forming a miRNA-hub gene network. Immune microenvironment variances were assessed with MCP and TIMER. Potential small molecules for ICH were forecasted via CMap database.

RESULTS

64 DEMFRGs and ten hub genes potentially involved in various processes like ferroptosis, TNF signalling pathway, MAPK signalling pathway, and NF-kappa B signalling pathway were discovered. Several miRNAs were identified as shared targets of hub genes. The ICH group showed increased infiltration of monocytic lineage and myeloid dendritic cells compared to the Healthy group. Ten potential small molecule drugs (e.g. Zebularine, TWS-119, CG-930) were predicted via CMap.

CONCLUSION

Several shared genes between mitophagy and ferroptosis potentially drive ICH progression via TNF, MAPK, and NF-kappa B pathways. These results offer valuable insights for further exploring the connection between mitophagy, ferroptosis, and ICH.

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.

Relevance of Porcine Stroke Models to Bridge the Gap from Pre-Clinical Findings to Clinical Implementation

In the search of animal stroke models providing translational advantages for biomedical research, pigs are large mammals with interesting brain characteristics and wide social acceptance. Compared to rodents, pigs have human-like highly gyrencephalic brains. In addition, increasingly through phylogeny, animals have more sophisticated white matter connectivity; thus, ratios of white-to-gray matter in humans and pigs are higher than in rodents. Swine models provide the opportunity to study the effect of stroke with emphasis on white matter damage and neuroanatomical changes in connectivity, and their pathophysiological correlate. In addition, the subarachnoid space surrounding the swine brain resembles that of humans. This allows the accumulation of blood and clots in subarachnoid hemorrhage models mimicking the clinical condition. The clot accumulation has been reported to mediate pathological mechanisms known to contribute to infarct progression and final damage in stroke patients. Importantly, swine allows trustworthy tracking of brain damage evolution using the same non-invasive multimodal imaging sequences used in the clinical practice. Moreover, several models of comorbidities and pathologies usually found in stroke patients have recently been established in swine. We review here ischemic and hemorrhagic stroke models reported so far in pigs. The advantages and limitations of each model are also discussed.

Curcumin, encapsulated in nano-sized PLGA, down-regulates nuclear factor κB (p65) and subarachnoid hemorrhage induced early brain injury in a rat model

BACKGROUND

More and more evidence revealed early brain injury (EBI) may determine the final outcome in aneurismal subarachnoid hemorrhage (SAH) patients. This study is of interest to examine the efficacy of nano-particle curcumin (nanocurcumin), a diarylheptanoid, on a SAH-induced EBI model.

METHODS

A rodent double hemorrhage model was employed. Nanocurcumin (75/150/300μg/kg/day) was administered via osmotic mini-pump post-SAH. CSF samples were collected to examine IL-1β, IL-6, IL-8 and TNF-α (rt-PCR). Cerebral cortex was harvested for NF-κB (p50/p65) (western blot), caspases (rt-PCR) measurement.

RESULTS

Nanocurcumin significantly reduced the bio-expression of NF-κB (p65), when compared with the SAH groups. The levels of IL-1β and IL-6 were increased in animals subjected to SAH, compared with the healthy controls, but absent in the high dose nanocurcumin+SAH group. Moreover, the levels of TNF-α in the SAH groups were significantly elevated. Treatment with nanocurcumin (300μg/kg) reduced the level to the healthy control. The cleaved caspase-3 and -9a was significantly reduced in 300μg/kg nanocurcumin treatment groups (P<0.05).

CONCLUSION

Treatment with nanocurcumin exerts its neuroprotective effect through the upward regulation of NF-κB (p65) and also reduced mitochondrion related caspase-9a expression. Besides, nanocurcumin decreased CSF levels of TNF-α and IL-1β, which may contribute to the extrinsic antiapoptotic effect. This study shows promise to support curcuminin, in a nano-particle, could attenuate SAH induced EBI.

Intracisternal administration of SB203580, a p38 mitogen-activated protein kinase inhibitor, attenuates cerebral vasospasm via inhibition of tumor-necrosis factor-α

Tumor-necrosis factor-α (TNF-α) is critical to the development of cerebral vasospasm after subarachnoid hemorrhage (SAH). Hence, therapeutic strategies targeting TNF-α can attenuate cerebral vasospasm. This study investigated the effects of SB203580, a p38 mitogen-activated protein kinase (MAPK) inhibitor, on TNF-α concentration in the cerebral arteries and the cerebrospinal fluid (CSF) after SAH and on subsequent cerebral vasospasm. Twenty-three rabbits were divided into four groups: (i) control (without SAH), (ii) SAH (SAH only), (iii) dimethylsulfoxide (DMSO, vehicle), and (iv) SB203580. The severity of vasospasm and the immunoreactivities of TNF-α and phosphorylated p38 MAPK in the brain vessels were determined in all animals, and the concentrations of TNF-α in the CSF were also assessed. Severe vasospasm was observed in the rabbits from the SAH and DMSO groups. SB203580 reversed vasospasm after SAH. Lower immunoreactivities of TNF-α and phosphorylated p38 MAPK were found in the basilar artery in the SB203580 group than in the DMSO group. The concentration of TNF-α in the CSF increased after SAH, but treatment with SB203080 after SAH suppressed this increase. Our data show that SB203580 reversed cerebral vasospasm by inhibiting the phosphorylation of p38 MAPK in the basilar artery and by suppressing the increase in TNF-α in the basilar artery and CSF after SAH. SB203580 could therefore potentially be used for the treatment of cerebral vasospasm after SAH.

Inhibition of cerebrovascular raf activation attenuates cerebral blood flow and prevents upregulation of contractile receptors after subarachnoid hemorrhage

BACKGROUND

Late cerebral ischemia carries high morbidity and mortality after subarachnoid hemorrhage (SAH) due to reduced cerebral blood flow (CBF) and the subsequent cerebral ischemia which is associated with upregulation of contractile receptors in the vascular smooth muscle cells (SMC) via activation of mitogen-activated protein kinase (MAPK) of the extracellular signal-regulated kinase (ERK)1/2 signal pathway. We hypothesize that SAH initiates cerebrovascular ERK1/2 activation, resulting in receptor upregulation. The raf inhibitor will inhibit the molecular events upstream ERK1/2 and may provide a therapeutic window for treatment of cerebral ischemia after SAH.

RESULTS

Here we demonstrate that SAH increases the phosphorylation level of ERK1/2 in cerebral vessels and reduces the neurology score in rats in additional with the CBF measured by an autoradiographic method. The intracisternal administration of SB-386023-b, a specific inhibitor of raf, given 6 h after SAH, aborts the receptor changes and protects the brain from the development of late cerebral ischemia at 48 h. This is accompanied by reduced phosphorylation of ERK1/2 in cerebrovascular SMC. SAH per se enhances contractile responses to endothelin-1 (ET-1), 5-carboxamidotryptamine (5-CT) and angiotensin II (Ang II), upregulates ETB, 5-HT1B and AT1 receptor mRNA and protein levels. Treatment with SB-386023-b given as late as at 6 h but not at 12 h after the SAH significantly decreased the receptor upregulation, the reduction in CBF and the neurology score.

CONCLUSION

These results provide evidence for a role of the ERK1/2 pathway in regulation of expression of cerebrovascular SMC receptors. It is suggested that raf inhibition may reduce late cerebral ischemia after SAH and provides a realistic time window for therapy.

Blockade of the MEK/ERK pathway with a raf inhibitor prevents activation of pro-inflammatory mediators in cerebral arteries and reduction in cerebral blood flow after subarachnoid hemorrhage in a rat model

Cerebral ischemia that develops after subarachnoid hemorrhage (SAH) carries high morbidity and mortality. Inflammatory mediators are involved in the development of cerebral ischemia through activation of the mitogen-activated protein kinase pathway. We hypothesized that blockade of the MAPkinase/ERK (MEK)/extracellular signal-regulated kinase (ERK) pathway upstream with a specific raf inhibitor would prevent SAH-induced activation of the cerebrovascular inflammatory response. The raf inhibitor SB-386023-b was injected intracisternally in our rat model at 0, 6, or 12 hours after the SAH. After 48 hours, cerebral arteries were harvested, and iNOS, interleukin (IL)-6, IL-1β, matrix metalloproteinase (MMP)-9, tissue inhibitors of metalloproteinase (TIMP)-1, and phosphorylated ERK1/2 were investigated by immunofluorescence, real-time polymerase chain reaction (PCR), and Western blot analysis. Cerebral blood flow (CBF) was measured using autoradiography. Protein levels of MMP-9, TIMP-1, iNOS, IL-6, and IL-1β were increased after SAH, as were mRNA levels of IL-6, MMP-9, and TIMP-1. After SAH, pERK1/2 was increased, but CBF was reduced. Treatment with SB-386023-b at 0 or 6 hours after SAH normalized CBF and prevented SAH-induced upregulation of MMPs, pro-inflammatory cytokines, and pERK1/2 proteins. These results suggested that inhibition of MEK/ERK signal transduction by a specific raf inhibitor administered up to 6 hours after SAH normalized the expression of pro-inflammatory mediators and extracellular matrix-related genes.

Mitogen-activated protein kinases in cerebral vasospasm after subarachnoid hemorrhage: a review

BACKGROUND

Mitogen-activated protein kinases (MAPKs) have been implicated in the pathogenesis of cerebral vasospasm after subarachnoid hemorrhage. The goal of this review is to bring together recent diverse data concerning the roles of MAPKs in cerebral vasospasm and to consider the future research.

METHOD

A review of publications in the National Library of Medicine and National Institutes of Health database was conducted in August 2009 using specific keyword search terms pertaining to subarachnoid hemorrhage and MAPKs.

FINDINGS

There are nine in vitro studies and 17 in vivo studies published. Most of previous studies used MAPK inhibitors or their upstream molecule inhibitors, and showed that MAPK inhibitions prevented vasospasm. The MAPK cascade appears to interact with other signaling molecules, and MAPK may be an important final common pathway for the signaling transduction during cerebral vasospasm. However, the mechanism by which MAPK causes sustained vascular smooth muscle contraction remains unclear. In addition, the role of endogenous MAPK inhibitors, MAPK phosphatases, has not been investigated in cerebral vasospasm.

CONCLUSIONS

The experimental data support the causative role of MAPK in cerebral vasospasm and warrant further research.

Improvement in neurological outcome and abolition of cerebrovascular endothelin B and 5-hydroxytryptamine 1B receptor upregulation through mitogen-activated protein kinase kinase 1/2 inhibition after subarachnoid hemorrhage in rats

OBJECT

Delayed cerebral ischemia after subarachnoid hemorrhage (SAH) remains a major cause of death and disability. It has been hypothesized that cerebrovascular upregulation of vasoconstrictor receptors is a key step in the development of delayed cerebral ischemia. Upregulation of endothelin-B (ET(B)) and 5-hydroxytryptamine 1B (5-HT(1B)) receptors has been demonstrated in cerebral artery smooth muscles in the delayed ischemic phase after experimental SAH, and intracellular signaling via the mitogen-activated protein kinase kinase (MEK)-extracellular signal-regulated kinase 1/2 pathway has been shown to be involved in this upregulation. The aim in the present study was to determine whether treatment with the MEK1/2 inhibitor U0126 can prevent cerebrovascular receptor upregulation and improve functional outcome after experimental SAH in rats.

METHODS

Subarachnoid hemorrhage was induced in male Sprague-Dawley rats by the injection of 250 μl of autologous blood into the basal cisterns. Either U0126 or vehicle was intracisternally administered at 6, 12, 24, and 36 hours after SAH. Smooth muscle ET(B) and 5-HT(1B) receptor upregulation was studied in isolated cerebral artery segments through immunohistochemical and myographic studies of contractile responses to receptor-specific agonists. Gross sensorimotor function in the rats after SAH was assessed using a rotating pole test.

RESULTS

Contractile concentration-response curves for middle cerebral artery (MCA) and basilar artery (BA) segments to endothelin-1 (ET-1) and 5-carboxamidotryptamine (5-CT) were shifted leftward for SAH-induced compared with shamoperated rats due to enhanced contractile responses to individual doses of the agonists (for example, contractile responses of the BA to 3 × 10(-10) M of ET-1 and 3 × 10(-7) M of 5-CT were 9.98 ± 5.01% and 16.75 ± 3.62% of the maximal contractile capacity, respectively, in sham-operated rats and 62.78 ± 9.9% and 45.44 ± 10.62%, respectively, in SAH-induced rats). In vivo treatment with 0.19 μg/kg U0126 normalized responses in the SAH-induced rats to levels in the sham-operated rats. Protein expression of ET(B) and 5-HT(1B) receptors in cerebrovascular smooth muscles from SAH-induced rats was increased to 175 ± 33.17% and 167.7 ± 24.74%, respectively, of the levels in sham-operated rats. Endothelin-B and 5-HT(1B) expression levels in U0126-treated SAH-induced rats were at the levels in sham-operated rats (101.9 ± 13.38% and 91.44 ± 16.75%, respectively). In a rotating pole test used to assess gross sensorimotor function on the 2nd day after surgery, sham-operated rats achieved an average score of 5.37 ± 0.23, SAH-induced rats scored 3.35 ± 0.67, and SAH-induced U0126-treated rats scored 5.00 ± 0.4.

CONCLUSIONS

The authors demonstrated that experimental SAH induces upregulation of ET(B) and 5-HT(1B) receptors in cerebrovascular smooth muscles and that treatment with the MEK1/2 inhibitor U0126 abolishes this receptor upregulation. They also demonstrated that experimental SAH results in sensorimotor deficits as assessed by a rotating pole test. These deficits were alleviated by U0126 treatment, suggesting that cerebrovascular receptor upregulation is critical for the functional outcome of delayed cerebral ischemia. The authors suggest that inhibition of MEK1/2 may be a promising new SAH treatment strategy.

Role of ERK1/2 and vascular cell proliferation in cerebral vasospasm after experimental subarachnoid hemorrhage

BACKGROUND

Although there are still some unresolved aspects, current research has revealed that vascular cell proliferation probably plays an important part in the pathological formation process of cerebral vasospasm. Using a "two-hemorrhage" model of subarachnoid hemorrhage (SAH), this study investigated the function of ERK1/2 and vascular wall cell proliferation in pathological development of cerebral vasospasm.

METHODS

Fifty rabbits were randomly divided into five groups: (1) SAH day 1, (2) SAH day 3, (3) SAH day 7, (4) SAH + DMSO (dimethyl sufoxide) solution, (5) SAH + PD98059 (a mitogen-activated protein kinase inhibitor) dissolved in DMSO solution. In the SAH + PD98059/DMSO group and SAH + DMSO control group, PD98059 in DMSO (2 mmol/l) or an equal quantity of DMSO, respectively, was injected into the cisterna magna, once a day from SAH day 1 to day 3. Western protein blotting was used to detect the expression of proliferating cell nuclear antigen (PCNA) and extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) in each group's basilar arteries. Light microscopy and electron microscopy were used for dynamic histological detection at each observation point of the SAH vascular wall under the effects of SAH and the mitogen-activated protein kinase inhibitor. Another 18 rabbits were randomly divided into three groups: SAH, SAH + DMSO and SAH + PD98059/DMSO; cerebral angiograpathy was conducted on SAH days 1 and 7, and the progression of angiographic vasospasm evaluated.

RESULTS

Compared with the control group, the extent of vasospasm after SAH increased with time. PD98059 significantly reduced angiographic and morphological vasospasm. In cerebral vasospasm, the expression of T-ERK1/2 showed no significant change. However, expression of p-ERK1/2 and PCNA began to increase significantly on day 3, and achieved a peak on day 7. PD98059 significantly inhibited the expression of p-ERK1/2 and PCNA (p < 0.05).

CONCLUSIONS

Cell proliferation on the vascular wall plays an important part in the pathological formation process of cerebral vasospasm. ERK1/2 phosphorylation, as an important signaling pathway, taking part in the process of vascular-wall pathological proliferation of cerebral vasospasm.

Neurological and neurobehavioral assessment of experimental subarachnoid hemorrhage

About 50% of humans with aneurysmal subarachnoid hemorrhage (SAH) die and many survivors have neurological and neurobehavioral dysfunction. Animal studies usually focused on cerebral vasospasm and sometimes neuronal injury. The difference in endpoints may contribute to lack of translation of treatments effective in animals to humans. We reviewed prior animal studies of SAH to determine what neurological and neurobehavioral endpoints had been used, whether they differentiated between appropriate controls and animals with SAH, whether treatment effects were reported and whether they correlated with vasospasm. Only a few studies in rats examined learning and memory. It is concluded that more studies are needed to fully characterize neurobehavioral performance in animals with SAH and assess effects of treatment.

Molecular mechanisms of cerebral vasospasm following aneurysmal SAH

Cerebral vasospasm following aneurysmal vasospasm has been the subject of intensive research. However the underlying pathophysiological mechanisms remain obscure. This article should summarize the present state concerning smooth muscle contraction, endothelial dysfunction, inflammatory changes, gene expression, in the genesis of vasospasm following aneurysmal subarachnoid hemorrhage.

Activation of c-jun in the rat basilar artery after subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) initiates a series of cellular and molecular events, some of which involve a mitogen activated protein kinase, c-jun N-terminal kinase (JNK). However, precise details regarding activation of c-jun in the vessel wall after SAH largely remain to be elucidated. In this study, we therefore investigated the localization and time-dependent expression of c-jun in the rat basilar artery after SAH in a rat single-hemorrhage model featuring infusion of autologous arterial blood. Basilar arteries were obtained at 2, 6 and 12h and 1, 2, 4 and 7 days after SAH, as well as from controls. Western blot analysis with c-jun, phosphorylated c-jun at Ser(63), and actin antibodies revealed that c-jun was immediately phosphorylated at Ser(63) within 2h, thereafter gradually becoming dephosphorylated, while total c-jun and actin levels remained almost unchanged. Immunohistochemistry demonstrated phosphorylation of c-jun at Ser(63) to occur in smooth muscle cells of the basilar artery 2h after SAH. These results indicate that c-jun is activated in the basilar artery immediately after the onset of SAH, presumably resulting in transcription of immediate early genes and smooth muscle cell proliferation.

THE ADENOSINE 2A RECEPTOR AGONIST ATL-146E ATTENUATES EXPERIMENTAL POSTHEMORRHAGIC VASOSPASM

OBJECTIVE

Selective adenosine 2A receptor agonists, such as ATL-146e, are known to be potent anti-inflammatory agents devoid of systemic side effects and have been used clinically in a number of disease states. However, adenosine 2A receptor agonists have not been studied in the treatment of cerebral vasospasm after subarachnoid hemorrhage. The present study investigated the efficacy of ATL-146e in the prevention of leukocyte infiltration and attenuation of posthemorrhagic vasospasm.

METHODS

The rodent femoral artery model of vasospasm was used. Forty male Sprague-Dawley rats were randomly assigned to four different groups (vehicle, 1 ng/kg/min, 10 ng/kg/min, or 100 ng/kg/min ATL-146e administered via subcutaneous osmotic minipump). Vasospasm was evaluated at posthemorrhage Day 8 (period of peak constriction) by calculating the lumen cross-sectional area (expressed as percent change in luminal area: ratio of blood-exposed vessel to normal saline-exposed vessel) and radial wall thickness. Immunostaining with anti-CD45 monoclonal antibody to detect leukocytes was used to evaluate localized inflammation.

RESULTS

Significant vasospasm was noted in the vehicle-treated (blood-exposed) control group (78.5%, P < 0.001; expressed as a ratio of luminal area of the saline [no blood] control), but not in the ATL-146e-treated groups (lumen ratio to control: 105.0, 83.4, and 91.3% for the 1, 10, and 100 ng/kg/min groups, respectively). Additionally, infiltration of inflammatory cells was reduced significantly and radial wall thickness was decreased in the ATL-146e-treated groups compared with the vehicle-treated control group.

CONCLUSION

Selective activation of the adenosine 2A receptor with ATL-146e prevented posthemorrhagic vasospasm and reduced leukocyte infiltration in this experimental model. This agent is worthy of further investigation and lends credence to the hypothesis supporting a role for inflammation in the pathogenesis of cerebral vasospasm after subarachnoid hemorrhage.

Ion channels and calcium signaling in cerebral arteries following subarachnoid hemorrhage

Entry of Ca(2+) through voltage-dependent calcium channels (VDCCs) is critical to the regulation of intracellular free calcium concentration ([Ca(2+)](i)) in vascular smooth muscle and thus the control of cerebral artery diameter. Increased VDCC activity in cerebral artery myocytes may contribute to decreased cerebral blood flow and the accompanying neurological deficits associated with subarachnoid hemorrhage (SAH). This review will focus on the impact of SAH on VDCCs and K(+)-selective ion channels, two important classes of ion channels located in the plasma membrane of cerebral artery myocytes. SAH may act through a variety of direct and indirect mechanisms to increase the activity of VDCCs promoting cerebral artery constriction and reduced cerebral blood flow. Further, SAH may lead to suppression of K(+) channel activity to cause membrane potential depolarization to enhance VDCC activity. The ability of VDCC blockers or K(+) channel activators to alleviate SAH-induced vasospasm will also be examined.

ERK1/2 inhibition attenuates cerebral blood flow reduction and abolishes ET(B) and 5-HT(1B) receptor upregulation after subarachnoid hemorrhage in rat

Upregulation of endothelin B (ET(B)) and 5-hydroxytryptamine 1B (5-HT(1B)) receptors via transcription has been found after experimental subarachnoid hemorrhage (SAH), and this is associated with enhanced phosphorylation of the mitogen-activated protein kinase (MAPK) extracellular signal-regulated kinase (ERK1/2). In the present study, we hypothesized that inhibition of ERK1/2 alters the ET(B) and 5-HT(1B) receptor upregulation and at the same time prevents the sustained cerebral blood flow (CBF) reduction associated with SAH. The ERK1/2 inhibitor SB386023-b was injected intracisternally in conjunction with and after the induced SAH in rats. At 2 days after the SAH, cerebral arteries were harvested for quantitative real-time polymerase chain reaction, immunohistochemistry and analysis of contractile responses to endothelin-1 (ET-1; ET(A) and ET(B) receptor agonist) and 5-carboxamidotryptamine (5-CT; 5-HT1 receptor agonist) in a sensitive myograph. To investigate if ERK1/2 inhibition had an influence on the local and global CBF after SAH, an autoradiographic technique was used. At 48 h after induced SAH, global and regional CBF were reduced by 50%. This reduction was prevented by treatment with SB386023-b. The ERK1/2 inhibition also decreased the maximum contraction elicited by application of ET-1 and 5-CT in cerebral arteries compared with SAH. In parallel, ERK1/2 inhibition downregulated ET(B) and 5-HT(1B) receptor messenger ribonucleic acid and protein levels compared with the SAH. Cerebral ischemia after SAH involves vasoconstriction and subsequent reduction in the CBF. The results suggest that ERK1/2 inhibition might be a potential treatment for the prevention of cerebral vasospasm and ischemia associated with SAH.

Signaling pathways for early brain injury after subarachnoid hemorrhage

Few studies have examined the signaling pathways that contribute to early brain injury after subarachnoid hemorrhage (SAH). Using a rat SAH model, the authors explored the role of vascular endothelial growth factor (VEGF) and mitogen-activation protein kinase (MAPK) in early brain injury. Male Sprague-Dawley rats (n = 172) weighing 300 to 350 g were used for the experimental SAH model, which was induced by puncturing the bifurcation of the left anterior cerebral and middle cerebral arteries. The blood-brain barrier (BBB), brain edema, intracranial pressure, and mortality were evaluated at 24 hours after SAH. The phosphorylation of VEGF and different MAPK subgroups (ERK1/2, p38, and JNK) were examined in both the cortex and the major cerebral arteries. Experimental SAH increased intracranial pressure, BBB permeability, and brain edema and produced high mortality. SAH induced phosphorylation of VEGF and MAPKs in the cerebral arteries and, to a lesser degree, in the cortex. PP1, an Src-family kinase inhibitor, reduced BBB permeability, brain edema, and mortality and decreased the phosphorylation of VEGF and MAPKs. The authors conclude that VEGF contributes to early brain injury after SAH by enhancing the activation of the MAPK pathways, and that the inhibition of these pathways might offer new treatment strategies for SAH.

Role of p38 mitogen-activated protein kinase on cerebral vasospasm after subarachnoid hemorrhage

BACKGROUND AND PURPOSE

Inflammatory cytokines are involved in the pathogenesis of cerebral vasospasm after subarachnoid hemorrhage (SAH). This study was conducted to examine the role of p38 mitogen-activated protein kinase (MAPK) in the development of vasospasm and cytokine production.

METHODS

We measured the expression levels of genes and proteins related to inflammation in human vascular smooth muscle cells (hVSMCs) treated with hemolysate and FR167653 (FR) (1 micromol/L), a selective p38MAPK inhibitor, for 48 hours by TaqMan real-time reverse transcription-polymerase chain reaction (RT-PCR) and ELISA. Twenty-one dogs were assigned to 3 groups of 7 animals: control, placebo, and FR-treated (1 mg/kg/d) groups in a double-hemorrhage model. The effects were assessed through the caliber of the basilar artery, and the changes in gene expressions and the activation of p38MAPK were assessed by Western blot analysis.

RESULTS

Treatment of hVSMCs with hemolysate induced significant upregulation of interleukin (IL)-1alpha, IL-1beta, and IL-8 gene and protein expressions, which was suppressed significantly with FR. The mean vessel caliber on day 7, as a percentage of that of day 0, was 49% in the placebo, and 74% in the FR group (P=0.0001). The gene expression levels of IL-1alpha, IL-1beta, and IL-8 in the arterial wall were extremely elevated in the placebo, and significantly suppressed in the FR group (P=0.0027, 0.0002, and 0.0073). p38MAPK phosphorylation was stimulated in the placebo and hemolysate in vitro, and suppressed in the FR group.

CONCLUSIONS

These results suggest that p38MAPK is activated in the arterial wall after SAH, leading to the development of vasospasm, possibly through the upregulation of inflammatory cytokines.

Caspase inhibitors prevent endothelial apoptosis and cerebral vasospasm in dog model of experimental subarachnoid hemorrhage

Apoptosis in the endothelium of major cerebral arteries may play a role in the initiation and maintenance of cerebral vasospasm after subarachnoid hemorrhage (SAH). We tested the therapeutic effect of caspase inhibitors on endothelial apoptosis and on cerebral vasospasm in an established dog double-hemorrhage model. Thirty-one mongrel dogs were divided into five groups: control; SAH; SAH treated with vehicle [DMSO]; SAH treated with Ac-DEVD-CHO [a specific caspase-3 inhibitor]; and SAH treated with Z-VAD-FMK [a broad caspase inhibitor]. The inhibitors (100 microM) were injected into the cisterna magna daily from Day 0 through Day 3. Angiography was performed on Day 0 and Day 7. Histology, TUNEL staining, and immunohistochemistry were conducted on basilar arteries collected on Day 7 after SAH. Positive staining of TUNEL, poly(ADP)-ribose polymerase (PARP), caspase-3, and caspase-8 was observed in the endothelial cells of the spastic arteries. Double fluorescence labeling demonstrated co-localization of TUNEL with caspase-3 and TNFalpha receptor-1 (TNFR1). Ac-DEVD-CHO and Z-VAD-FMK prevented endothelial apoptosis and reduced angiographic vasospasm. The mechanism of apoptosis in endothelial cells involves TNFR1 and the caspase-8 and caspase-3 pathways. Caspase inhibitors may have potential in the treatment of cerebral vasospasm.

Contribution of Src tyrosine kinase to cerebral vasospasm after subarachnoid hemorrhage

OBJECT

Mitogen-activated protein kinase (MAPK) has been implicated in cerebral vasospasm after subarachnoid hemorrhage (SAH). This study was conducted to investigate whether Src tyrosine kinase, an upstream regulator of MAPK, is involved in cerebral vasospasm.

METHODS

An established canine double-hemorrhage model was used. Twenty-four dogs were divided into four groups: control, vehicle-treated, Src inhibitor PP2-treated, and Src inhibitor damnacanthal-treated groups. Vehicle (dimethyl sulfoxide), PP2, or damnacanthal was injected daily into the cisterna magna of 18 dogs at 3 to 6 days after induction of SAH. Angiography was performed on Day 0 (the day on which the first blood injection was administered to induce SAH) and on Day 7. Western blot analysis of Src and MAPK activation in basilar arteries (BAs) collected on Day 7 post-SAH was performed. Severe vasospasm was observed in the BAs of vehicle-treated dogs. Mild vasospasm was observed in all dogs treated with Src inhibitors. Phosphorylated Src and MAPK were increased after SAH and activation of these kinases in the BAs was abolished by PP2 and damnacanthal.

CONCLUSIONS

The tyrosine kinase Src is an important upstream regulator of MAPK, and inhibition of Src might offer a new therapy in the management of cerebral vasospasm.

Signal transduction pathways in cerebral vasospasm

Cerebral vasospasm is a deadly complication following the rupture of intracranial aneurysms. The time course of cerebral vasospasm is unique in that it is slow developing, usually takes 4-7 days to peak, but lasts up to 2-3 weeks, and is resistant to most known vasodilators. These special features make cerebral vasospasm the most important determinant in the outcome of patients suffering subarachnoid hemorrhage. The available treatment strategies include mechanical dilation of spastic cerebral arteries (angioplasty) and non-selective vasodilatation such as by Ca(2+) channel blockers. One new development in the experimental treatment of cerebral vasospasm is the looming target of signaling pathways. Understanding vasospastic signals in cerebral arteries might offer a new avenue for selective treatment of cerebral vasospasm in the future.

Therapeutic effect of caspase inhibitors in the prevention of apoptosis and reversal of chronic cerebral vasospasm

One of the important histological changes in cerebral vasospasm after subarachnoid hemorrhage (SAH) is endothelial cell damage, which involves apoptosis. The current study was undertaken to determine whether anti-apoptosis therapy prevents apoptosis and reverses vasospasm in a dog SAH model. Twenty-three mongrel dogs of either sex, weighing 17-25 kg, were subjected to autologous arterial blood injection into the cisterna magna on day 0 and day 2, and sacrificed on day 7. Angiography was performed on day 0 before blood injection and on day 7 before sacrifice. Caspase-2 (Z-VDVAD-FMK, 10 microM) inhibitor, caspase-3 (Z-DEVD-FMK, 10 microM) inhibitor, or vehicle (DMSO) were injected intrathecally from day 2 to day 6. The effects of caspase inhibitors on apoptosis and vasospasm were evaluated by angiography and transmission electron microscopy. The residual diameter of the basilar artery on day 7 in SAH dogs without treatment was 53.4+/-5.5% of the day 0 diameter. Marked damage to the endothelial cells, including apoptotic like changes, was observed in these arteries. Both caspase inhibitors prevented apoptosis in the endothelial cells. Only caspase-3 inhibitor, however, had a near-significant effect on reducing 13.3% of angiographic vasospasm. Higher doses and early treatment, as well as other more potent apoptosis inhibitors, are recommended for future studies.

Evaluation of the microvasculature and cerebral ischemia after experimental subarachnoid hemorrhage in dogs

OBJECT

Whether cerebral vasospasm occurs only in surface vessels or also in parenchymal arterioles is debatable. The present study was undertaken to evaluate comprehensively the microvasculature of the brainstem after experimental subarachnoid hemorrhage (SAH).

METHODS

Nine mongrel dogs of either sex, each weighing between 18 and 24 kg, underwent double blood injections spaced 48 hours apart; the injections were infused into the cisterna magna immediately after angiography of the basilar arteries (BAs). Three additional dogs assigned to a control group received no blood injections. The dogs were killed on Day 7. Axial sections obtained from the midpontine region of both control dogs and animals subjected to SAH were evaluated with respect to the morphological characteristics of vessels and neurons, and for ultrastructural changes. Severe vasospasm occurred in the BAs of all dogs subjected to SAH. Nevertheless, in these animals, the luminal areas and vessel perimeter in parenchymal arterioles, but not in parenchymal venules, were observed to have increased when compared with those of control dogs (p < 0.01, t-test). No corrugation of the internal elastic lamina was observed and smooth-muscle and endothelial cells remained normal at the ultrastructural level in the dogs with SAH.

CONCLUSIONS

In this model, vasospasm of the BAs did not extend into the region of the pons to affect the intraparenchymal arterioles. Dilation of the parenchymal arterioles might serve as compensation for reduced blood flow. Thus, no neuronal ischemia or infarction resulted in the pontine region of the brain.

Posttreatment with adenovirus-mediated gene transfer of calcitonin gene-related peptide to reverse cerebral vasospasm in dogs

OBJECT

Gene transfer to cerebral vessels is a promising new therapeutic approach for cerebral vasospasm after subarachnoid hemorrhage (SAH). This study was undertaken to explore whether a delayed treatment with adenovirus encoding the prepro-calcitonin gene-related peptide (CGRP), 2 days after initial blood injection, reduces cerebral vasospasm in a double-hemorrhage model of severe vasospasm in dogs.

METHODS

In 20 dogs, arterial blood was injected into the cisterna magna on Days 0 and 2. Thirty minutes after the second blood injection, the animals received either adenovirus encoding the prepro-CGRP gene (AdCMVCGRP-treated group, eight dogs) or adenovirus encoding the beta-galactosidase gene (AdCMVbeta gal-treated group, six dogs) under the cytomegalovirus (CMV) promoter. One group of dogs did not receive treatment and served as controls (control SAH group, six dogs). Angiography was performed on Days 0 and 7 to assess cerebral vasospasm. On Day 7 following angiography, the animals were killed and their brains were stained with X-gal to detect the distribution of gene expression. Cerebrospinal fluid (CSF) was also tested for CGRP immunoreactivity. Severe vasospasm was observed in control SAH dogs on Day 7, and the mean basilar artery (BA) diameter was 53.4 +/- 5.5% of the value measured on Day 0. Treatment with AdCMVbeta gal did not alter vasospasm (the BA diameter was 55 +/- 3.9% of that measured on Day 0). The leptomeninges and adventitia of the BAs of dogs treated using AdCMVbeta gal demonstrated positive staining with X-gal. High levels of CGRP were measured in CSF from dogs that received AdCMVCGRP. In the group treated with AdCMVCGRP, vasospasm was significantly reduced (the BA diameter was 78.2 +/- 5.3% of that measured on Day 0, p < 0.05 compared with the control SAH group and the AdCMVbeta gal group).

CONCLUSIONS

In a model of severe vasospasm in dogs, gene transfer of CGRP after injection of blood attenuated cerebral vasospasm after SAH.

Suramin-induced reversal of chronic cerebral vasospasm in experimental subarachnoid hemorrhage

OBJECT

The naphthylsulfonate derivative suramin is an inhibitor of growth factor receptors (receptor tyrosine kinases) and G protein-coupled P2Y receptors. Both types of these receptors are suspected of being involved in cerebral vasospasm after subarachnoid hemorrhage (SAH). In the current study, the authors examined the therapeutic effects of suramin and a selective P2X-receptor antagonist, pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid (PPADS), in the reversal of vasospasm in an established canine double-hemorrhage model.

METHODS

Twenty-four dogs underwent double blood injection into the cisterna magna, with injections given on Days 0 and 2. The dogs were divided randomly into three groups (six animals in each group) to be treated from Days 2 through 6 with the vehicle dimethyl sulfoxide, suramin, or PPADS. An additional group of six dogs received double blood injection without any treatment and served as an SAH control group. The animals were killed on Day 7. Angiography was performed on Day 0 before blood injection and again on Day 7 before the animals were killed. After the death of the animals, the basilar arteries (BAs) were collected for morphological studies and determination of tyrosine kinase expression, and the bloody cerebrospinal fluid (CSF) produced by the hemorrhages was collected for measurement of oxyhemoglobin and adenosine triphosphate (ATP). In the SAH control group, the mean diameter of the BAs on Day 7 was 46.23 +/- 6.32% of the value on Day 0 (which served as a reference of 100%). In the DMSO-treated group, the mean residual diameter of the BA was 47.77 +/- 0.8% on Day 7 compared with the value on Day 0. Suramin, but not PPADS, increased the residual diameter to 74.02 +/- 4.24% on Day 7. On Day 7 the level of ATP in the CSF was decreased and the level of oxyhemoglobin was increased, compared with values measured on Day 0. Suramin, but not PPADS, reduced tyrosine phosphorylation in the spastic BAs.

CONCLUSIONS

By reducing tyrosine kinase activity, suramin may be useful in the treatment of cerebral vasospasm.

Inhibitory effect with antisense mitogen-activated protein kinase oligodeoxynucleotide against cerebral vasospasm in rats

BACKGROUND AND PURPOSE

Mitogen-activated protein kinase (MAPK) may be associated with the pathogenesis of cerebral vasospasm after subarachnoid hemorrhage (SAH). This study aimed to clarify the role of MAPK expression and activation during cerebral vasospasm and to evaluate the therapeutic effect on cerebral vasospasm using an antisense MAPK oligodeoxynucleotide (ODN).

METHODS

Antisense MAPK, sense MAPK, or scrambled ODN was injected into the rats intracisternally. We used a single-hemorrhage experimental SAH model to assess vasospasm in the basilar arteries at 30 minutes, 1 day, and 2 days after SAH by cross-sectional area measurement and other histological parameters. Immunohistochemistry and Western blot analysis were used to quantify MAPK expression and activation. In addition, a double-hemorrhage rat SAH model was used to test the effect of post-SAH treatment with antisense MAPK ODN.

RESULTS

Antisense MAPK therapy significantly inhibited cerebral vasospasm when compared with sense MAPK or scrambled ODN treatment on day 2. The immunohistochemistry and Western blotting performed in the basilar artery of rats that received antisense MAPK ODN demonstrated inhibition of MAPK and phosphorylated MAPK on day 2. In post-SAH treatment study, antisense ODN reduced MAPK and phosphorylated MAPK in the basilar artery and attenuated cerebral vasospasm.

CONCLUSIONS

MAPK activation, but not expression, might be implicated with sustained smooth muscle contraction during cerebral vasospasm after SAH. This study suggests that antisense MAPK ODN strategy is an effective treatment against cerebral vasospasm.

Molecular mechanisms involved in development of cerebral vasospasm

Object

Although the agents responsible for production of vasospasm have not yet been clearly identified, the author reviews the molecular mechanisms involved in development of vasospasm mainly based on the experimental data in a canine two-hemorrhage model.

Methods

The blood products after subarachnoid hemorrhage most likely stimulate many cell membrane receptors, such as G protein–coupled receptors and receptor tyrosine kinases, to activate the tyrosine kinase pathway of the vascular smooth muscle cells. The activation of the tyrosine kinase pathway is associated with continuous elevation of intracellular Ca++levels and activation of μ-calpain; the former may result mainly not from Ca++release but from Ca++influx from outside the cells. The increased intracellular Ca++concentrations stimulate Ca++/calmodulin (CaM)–dependent myosin light chain kinase to phosphorylate myosin light chain continuously during vasospasm. A topical application of genistein, ethylene-glycol-bis(β-aminoethylether) N,N'-tetraacetic acid, or various L-type Ca++channel blockers likely induces reversal of vasospasm as a result of a decrease in intracellular Ca++levels. The blood products also activate the rho/rho-associated kinase pathway during vasospasm most likely via G protein–coupled receptors, and the activated rho-associated kinase inhibits myosin phosphatase through phosphorylation at its myosin-binding subunit to induce Ca++-independent development of vasospasm. The enhanced generation of arachidonic acid during vasospasm may also contribute to inhibition of myosin phosphatase, at least in part, through the rho/rho-associated kinase pathway. The activity of myosin phosphatase in vasospam can also be inhibited by activated protein kinase C independently of the rho/rho-associated kinase pathway, but the inhibition may play a minor and transient role in contractile regulation. The protein levels of thin filament–associated proteins, calponin and caldesmon, are progressively decreased in vasospasm, whereas their phosphorylation levels are increased. Both changes probably contribute to the enhancement of smooth muscle contractility. Contractile and cytoskeletal proteins appear to be degraded in vasospasm by proteolysis with activated μ-calpain, suggesting that the intracellular devices responsible for smooth-muscle contraction are severely degraded in vasospasm.

Conclusions

It remains to be determined the extent to which Ca++-dependent and -independent contractile regulations, proteolysis and phosphorylation of thin filament–associated proteins, and degradation of contractile and cytoskeletal proteins are involved in the development of vasospasm.

Phosphatidylinositol 3-kinase inhibitor failed to reduce cerebral vasospasm in dog model of experimental subarachnoid hemorrhage

BACKGROUND AND PURPOSE

Phosphatidylinositol 3-kinase (PI3-kinase) is involved in smooth muscle contraction induced by growth factors and/or G protein-coupled receptor agonists. To evaluate the role of PI3-kinase in the pathogenesis of delayed vasospasm, we applied 2 PI3-kinase inhibitors to an established canine double-hemorrhage model of experimental subarachnoid hemorrhage.

METHODS

Twenty-four dogs underwent double blood injections via the cisterna magna on days 0 and 2. The dogs were killed on day 7. Dogs were treated with either vehicle (dimethyl sulfoxide), wortmannin, or LY294002 once per day on day 2 through day 6. Angiography was performed before blood injection and before the dogs were killed. The basilar arteries were collected for morphology, Western blot analysis, and PI3-kinase activity.

RESULTS

The residual diameter of the basilar arteries in the dimethyl sulfoxide treatment group, which was compared with day 0 angiogram, decreased markedly on day 7 (the percentage of the residual diameter was 47.8+/-0.8%). Wortmannin and LY294002 did not significantly change residual diameter on day 7. Both PI3-kinase inhibitors abolished PI3-kinase activity compared with the vehicle treatment group. However, both PI3-kinase inhibitors failed to significantly attenuate PI3-kinase protein expression (Western blot) (P>0.05, ANOVA).

CONCLUSIONS

Delayed treatment, which was to mimic the clinical situation, with PI3-kinase inhibitors failed to reverse vasospasm. PI3-kinase may not play an important role in the delayed vasospasm. The possible effect of PI3-kinase inhibitors in the early stage of vasospasm was not investigated in the present study.

Sphingosine 1-phosphate contracts canine basilar arteries in vitro and in vivo: possible role in pathogenesis of cerebral vasospasm

BACKGROUND AND PURPOSE

Sphingosine 1-phosphate (S1P) is a platelet-derived bioactive lipid that exerts a variety of biological responses, including vasocontraction. To understand the involvement of S1P in cerebral vasospasm, we investigated the effect of S1P on vasocontraction of the canine basilar artery in vitro and in vivo.

METHODS

We recorded isometric tension in basilar arterial rings from dogs in vitro and estimated time-course changes in the diameter of canine basilar arteries and the S1P concentration in cerebrospinal fluid (CSF) by angiography and radioreceptor assays, respectively, after administering S1P into the cisterna magna. Changes in the supernatant S1P concentration during clot formation were monitored by using the in vitro subarachnoid hemorrhage model, in which blood is mixed with CSF.

RESULTS

At concentrations ranging between 100 nmol/L and 10 micromol/L, S1P induced a dose-dependent contraction of the basilar artery in vitro. This effect was significantly inhibited by Y-27632, a highly selective Rho-kinase inhibitor. The administration of S1P into the CSF induced a 60% to 70% decrease in the arterial diameter within 15 minutes, and vasocontraction continued for 2 days thereafter. The concentration of S1P in the supernatant during clot formation in vitro reached approximately 300 nmol/L.

CONCLUSIONS

S1P induces vasocontraction in the canine basilar artery in vitro and in vivo, possibly through a mechanism involving activation of the Rho/Rho-kinase pathway. Thus, S1P might be considered as a novel spasmogenic substance involved in cerebral vasospasm after subarachnoid hemorrhage.

Protein kinase C and cerebral vasospasm

Twenty-five years after the discovery of protein kinase C (PKC), the physiologic function of PKC, and especially its role in pathologic conditions, remains a subject of great interest with 30,000 studies published on these aspects. In the cerebral circulation, PKC plays a role in the regulation of myogenic tone by sensitization of myofilaments to calcium. Protein kinase C phosphorylates various ion channels including augmenting voltage-dependent Ca2+ channels and inhibiting K+ channels, which both lead to vessel contraction. These actions of PKC amplify vascular reactivity to different agonists and may be critical in the regulation of cerebral artery tone during vasospasm. Evidence accumulated during at least the last decade suggest that activation of PKC in cerebral vasospasm results in a delayed but prolonged contraction of major arteries after subarachnoid hemorrhage. Most of the experimental results in vitro or in animal models support the view that PKC is involved in cerebral vasospasm. Implication of PKC in cerebral vasospasm helps explain increased arterial narrowing at the signal transduction level and alters current perceptions that the pathophysiology is caused by a combination of multiple receptor activation, hemoglobin toxicity, and damaged neurogenic control. Activation of protein kinase C also interacts with other signaling pathways such as myosin light chain kinase, nitric oxide, intracellular Ca2+, protein tyrosine kinase, and its substrates such as mitogen-activated protein kinase. Even though identifying PKC revolutionized the understanding of cerebral vasospasm, clinical advances are hampered by the lack of clinical trials using selective PKC inhibitors.