17beta-Estradiol inhibits subarachnoid hemorrhage-induced inducible nitric oxide synthase gene expression by interfering with the nuclear factor kappa B transactivation

Oestrogen ameliorates blood-brain barrier damage after experimental subarachnoid haemorrhage via the SHH pathway in male rats

BACKGROUND

Sex differences affect the occurrence, progression and regression of subarachnoid haemorrhage (SAH). Oestrogen plays a protective role in alleviating the vasospasm and neuronal apoptosis induced by SAH. However, whether oestrogen affects blood‒brain barrier (BBB) integrity has not been fully studied. Oestrogen has been found to regulate the sonic hedgehog (SHH) signalling pathway through the oestrogen receptor in gastric cancer and adrenal glands, and the SHH signalling pathway has an important role in maintaining the BBB by upregulating the expression of tight junction proteins. In this study, we investigated the relationship between oestrogen and the SHH signalling pathway using clinical data and established an experimental SAH model to explore whether oestrogen could ameliorate BBB damage after SAH through the SHH pathway.

METHODS

Correlations between oestrogen and the SHH pathway were analysed by patients' cerebrospinal fluid (CSF) samples and the Genotype-Tissue Expression database (GTEx). Then, an experimental rat SAH model was established using the endovascular perforation method and treated with oestrogen, oestrogen inhibitors and SHH signalling pathway inhibitors. Then, the effects of oestrogen on BBB damage were analysed by western blot, immunofluorescence and neurobehavioural experiments.

RESULTS

ESLIA detection and correlation analysis showed that oestrogen levels in patients' CSF were positively correlated with the SHH pathway, which was further verified by GTEx gene-correlation analysis. SHH was found to be mainly expressed in neurons and astrocytes in rats under physiological conditions and was upregulated by oestrogen pretreatment. In the SAH model, oestrogen pretreatment was found to reverse SAH-induced decreases in the SHH pathway, which were counteracted by oestrogen receptor inhibitors. Furthermore, oestrogen pretreatment reduced SAH-induced BBB damage, brain oedema and neurological dysfunction, which were eliminated by SHH pathway inhibitors.

CONCLUSION

In conclusion, we demonstrate here that oestrogen pretreatment ameliorates brain injury after SAH, at least in part through SHH pathway-mediated BBB protection.

The blood-brain barrier and the neurovascular unit in subarachnoid hemorrhage: molecular events and potential treatments

The response of the blood-brain barrier (BBB) following a stroke, including subarachnoid hemorrhage (SAH), has been studied extensively. The main components of this reaction are endothelial cells, pericytes, and astrocytes that affect microglia, neurons, and vascular smooth muscle cells. SAH induces alterations in individual BBB cells, leading to brain homeostasis disruption. Recent experiments have uncovered many pathophysiological cascades affecting the BBB following SAH. Targeting some of these pathways is important for restoring brain function following SAH. BBB injury occurs immediately after SAH and has long-lasting consequences, but most changes in the pathophysiological cascades occur in the first few days following SAH. These changes determine the development of early brain injury as well as delayed cerebral ischemia. SAH-induced neuroprotection also plays an important role and weakens the negative impact of SAH. Supporting some of these beneficial cascades while attenuating the major pathophysiological pathways might be decisive in inhibiting the negative impact of bleeding in the subarachnoid space. In this review, we attempt a comprehensive overview of the current knowledge on the molecular and cellular changes in the BBB following SAH and their possible modulation by various drugs and substances.

Possible involvement of female sex steroid hormones in intracellular signal transduction mediated by cytokines following traumatic brain injury

INTRODUCTION

The aim of this study was to determine the anti-inflammatory effect of female sex hormones on the level of intracellular molecules of cytokine signaling pathway after diffuse traumatic brain injury (TBI) in ovariectomized rats.

METHODS

Female rats were divided into 10 groups: control, sham, TBI, Vehicle (oil), Vehicle E1 (33.3 µg/kg), E2 (1 mg / kg), P1 (1.7 mg/kg), P2 (8 mg / kg), E2 + P1. All drugs were injected 0.5 h after TBI. Brain edema and the brain levels of P-STAT-3, NFκB-P52, NFκB-P65, P-IκB, and SOCS-3 by immunohistochemistry measured at 24 h after TBI.

RESULTS

Increased brain edema after TBI was inhibited by different doses of estrogen, progesterone (P < 0.001), and E2 + P1 (P < 0.05). The brain levels of P-STAT-3, NFκB-P52, NFκB-P65, and p-IκBα that increased after TBI was decreased only by E2 (P < 0.05). E2 and E2 + P1 have increased the SOCS-3 level after TBI (P < 0.05). Also, there was a difference between the E2 with E1 and two progesterone doses (P < 0.05). So that in all cases, the effects of E2 were more significant than the other groups. The target cells for these effects of E2 were microglia and astrocytes.

CONCLUSION

The results indicate that one of the probable mechanism(s) of estrogen anti-inflammatory effect after TBI is either reduction of p-STAT-3, NFκB-P52, p-NFκB-P65, and p-IκBα or increase in SOCS-3 molecules involved in the signaling pathway of inflammatory cytokines.

In vivo assessment of respiratory burst inhibition by xenobiotic exposure using larval zebrafish

Currently, assessment of the potential immunotoxicity of a given agent involves a tiered approach for hazard identification and mechanistic studies, including observational studies, evaluation of immune function, and measurement of susceptibility to infectious and neoplastic diseases. These studies generally use costly low-throughput mammalian models. Zebrafish, however, offer an excellent alternative due to their rapid development, ease of maintenance, and homology to mammalian immune system function and development. Larval zebrafish also are a convenient model to study the innate immune system with no interference from the adaptive immune system. In this study, a respiratory burst assay (RBA) was utilized to measure reactive oxygen species (ROS) production after developmental xenobiotic exposure. Embryos were exposed to non-teratogenic doses of chemicals and at 96 h post-fertilization, the ability to produce ROS was measured. Using the RBA, 12 compounds with varying immune-suppressive properties were screened. Seven compounds neither suppressed nor enhanced the respiratory burst; five reproducibly suppressed global ROS production, but with varying potencies: benzo[a]pyrene, 17β-estradiol, lead acetate, methoxychlor, and phenanthrene. These five compounds have all previously been reported as immunosuppressive in mammalian innate immunity assays. To evaluate whether the suppression of ROS by these compounds was a result of decreased immune cell numbers, flow cytometry with transgenic zebrafish larvae was used to count the numbers of neutrophils and macrophages after chemical exposure. With this assay, benzo[a]pyrene was found to be the only chemical that induced a change in the number of immune cells by increasing macrophage but not neutrophil numbers. Taken together, this work demonstrates the utility of zebrafish larvae as a vertebrate model for identifying compounds that impact innate immune function at non-teratogenic levels and validates measuring ROS production and phagocyte numbers as metrics for monitoring how xenobiotic exposure alters the innate immune system.

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.

Concentrations of estradiol, progesterone and testosterone in sefrum and cerebrospinal fluid of patients with aneurysmal subarachnoid hemorrhage correlate weakly with transcranial Doppler flow velocities

Background

The implication of the steroids estradiol, progesterone and testosterone in cerebral vasospasm after aneurysmal subarachnoid hemorrhage (aSAH) has not been comprehensively assessed. In rodents, studies suggested beneficial effects of steroids on cerebral vasospasm after experimental SAH. Studies in humans are warranted, however, a general dilemma of human studies on neuroactive substances is that the brain is not directly accessible and that concentrations in the periphery may not adequately parallel concentrations in the central compartments. In the present study, concentrations of estradiol, progesterone and testosterone in serum and cerebrospinal fluid (CSF) of patients with aSAH were determined. Blood flow velocities in cerebral arteries were measured by transcranial Doppler sonography (TCD). The aim of this study was to evaluate the correlations between the cerebral blood flow velocities and levels of estradiol, progesterone and testosterone in CSF and serum.

Results

Samples of serum and CSF of 42 patients with aSAH were collected concomitantly daily or every other day via the arterial line and the external ventricular drainage for two weeks after the hemorrhage. Blood flow velocities in the cerebral arteries were determined by TCD. Total estradiol, progesterone and testosterone concentrations were measured by electro-chemiluminescence immunoassay. The strength of correlation was assessed by Spearman’s rank correlation coefficient. The correlation analysis revealed very weak correlations between cerebral blood flow velocities and concentrations of estradiol, progesterone and testosterone levels in both compartments with correlation coefficients below 0.2.

Conclusions

In humans with aSAH, merely very weak correlations between flow velocities in cerebral arteries and concentrations of estradiol, progesterone and testosterone in serum and CSF were demonstrated. These results suggest a limited influence of the respective steroids on cerebral vascular tone although vasodilatory effects were described in rodent studies. Thus, the implication of steroids in processes of neurological deterioration warrants further clarification.

Influence of sex and hormonal status on initial impact and neurocognitive outcome after subarachnoid haemorrhage in rats

The aim of this study was to detect differences in functional outcome after experimental subarachnoid haemorrhage (SAH) in rodents with different hormonal status. For this purpose, the endovascular perforation model was applied to four groups of Sprague-Dawley-Rats: male intact, male neutered, female intact and female neutered animals. Initial impact was measured by ICP, CPP and cerebral blood flow in the first hour after SAH. From day 4-14, the modified hole board test was applied to assess functional and neuro-cognitive outcome. Histological outcome was examined in the motor cortex and hippocampus of each hemisphere. Mortality was highest in the female intact group albeit not statistically significant. Physiologic parameters did not differ significantly between groups either. In the modified hole board test, male intact animals showed a greater impairment of declarative memory than the female intact and neutered groups. However, male intact animals showed greater avoidance behaviour and male animals revealed higher anxiety levels independent of hormonal status. No differences in histological damage of hippocampus and motor cortex between groups could be shown. We therefore speculate that the marginal deficits in cognitive performance that are shown by the male intact group in the modified hole board test are mostly caused by higher anxiety levels and cannot be interpreted as pure cognitive impairment.

Estradiol-mediated regulation of hepatic iNOS in obese rats: Impact of Src, ERK1/2, AMPKα, and miR-221

PURPOSE

This study aimed to investigate in vivo effects of estradiol on the regulation of hepatic inducible nitric oxide synthase (iNOS) expression in the high fat (HF) diet-induced obesity. Also, we aimed to investigate whether activation of the extracellular signal-regulated kinase (ERK1/2), adenosine monophosphate-activated protein kinase (AMPK), Src kinase, and miR-221 is involved in estradiol-mediated regulation of iNOS in the liver of obese male Wistar rats. Male Wistar rats were fed a standard laboratory diet or a HF diet for 10 weeks. Half of HF rats were treated with estradiol intraperitoneally (40 μg/kg), whereas the other half were placebo-treated 24 H before euthanasia. Results show that estradiol treatment of HF rats decreased hepatic iNOS mRNA (P < 0.05) and protein expression (P < 0.01), the protein levels of p65 subunit of nuclear factor κB (P < 0.05) and ERα (P < 0.05), ERK1/2 phosphorylation (P < 0.001), and ERα/Src kinase association (P < 0.05). By contrast, hepatic Src protein level (P < 0.05), AMPKα phosphorylation (P < 0.05), and miR-221 expression (P < 0.05) were increased in HF rats after estradiol treatment. Our results indicate that estradiol in vivo regulates hepatic iNOS expression in obese rats via molecular mechanisms involving ERK1/2, AMPK, Src, and miR-221 signaling.

Recombinant CTRP9 administration attenuates neuroinflammation via activating adiponectin receptor 1 after intracerebral hemorrhage in mice

Background

Neuroinflammation is a crucial factor contributing to neurological injuries after intracerebral hemorrhage (ICH). C1q/TNF-related protein 9 (CTRP9), an agonist of adiponectin receptor 1 (AdipoR1), has recently been shown to reduce inflammatory responses in systemic diseases. The objective of this study was to investigate the protective role of CTRP9 against neuroinflammation after ICH in a mouse model and to explore the contribution of adenosine monophosphate-activated protein kinase (AMPK)/nuclear factor kappa B (NFκB) pathway in AdipoR1-mediated protection.

Methods

Adult male CD1 mice (n = 218) were randomly assigned to different groups for the study. ICH was induced via intrastriatal injection of bacterial collagenase. Recombinant CTRP9 (rCTRP9) was administered intranasally at 1 h after ICH. To elucidate the underlying mechanism, AdipoR1 small interfering ribonucleic acid (siRNA) and selective phosphorylated AMPK inhibitor Dorsomorphin were administered prior to rCTRP9 treatment. Brain edema, short- and long-term neurobehavior evaluation, blood glucose level, western blot, and immunofluorescence staining were performed.

Results

Endogenous CTRP9 and AdipoR1 expression was increased and peaked at 24 h after ICH. AdipoR1 was expressed by microglia, neurons, and astrocytes. Administration of rCTRP9 reduced brain edema, improved short- and long-term neurological function, enhanced the expression of AdipoR1 and p-AMPK, and decreased the expression of phosphorylated NFκB and inflammatory cytokines after ICH. The protective effects of rCTRP9 were abolished by administration of AdipoR1 siRNA and Dorsomorphin.

Conclusions

Our findings demonstrated that administration of rCTRP9 attenuated neuroinflammation through AdipoR1/AMPK/NFκB signaling pathway after ICH in mice, thereby reducing brain edema and improving neurological function after experimental ICH in mice. Therefore, CTRP9 may provide a potential therapeutic strategy to alleviate neuroinflammation in ICH patients.

Electronic supplementary material

The online version of this article (10.1186/s12974-018-1256-8) contains supplementary material, which is available to authorized users.

Vasospasm-related complications after subarachnoid hemorrhage: the role of patients' age and sex

BACKGROUND

Outcome of aneurysmal subarachnoid hemorrhage (SAH) depends strongly on occurrence of symptomatic vasospasm (SV) leading to delayed cerebral ischemia (DCI). Various demographic, radiographic, and clinical predictors of SV have been reported so far, partially with conflicting results. The aim of this study was to analyze the role of patients' age and sex on SV/DCI risk, especially to identify age and sex-specific risk groups.

METHODS

All patients admitted with acute SAH during a 14-year-period ending in 2016 were eligible for this study. The study endpoints were the following: SV requiring spasmolysis, occurrence of DCI in follow-up computed tomography scans and unfavorable outcome at 6 months (modified Rankin scale > 2).

RESULTS

Nine hundred ninety-four patients were included in this study. The majority was female (666; 67%). SV, DCI, and unfavorable outcomes were observed in 21.5, 21.8, and 43.6% of the patients, respectively. Younger age (p < 0.001; OR = 1.03 per year decrease) and female sex (p = 0.025; OR = 1.510) were confirmed as independent predictors of SV. Regarding the sex differences, there were three age groups for SV/DCI risk ≤ 54, 55-74, and ≥ 75 years. Male patients showed earlier decrease in SV risk (at ≥ 55 vs. ≥ 75 years in females). Therefore, SAH females aged between 55 and 74 years were at the highest risk for DCI and unfavorable outcome, as compared to younger/older females (p = 0.001, OR = 1.77/p = 0.001, OR = 1.80). In contrast, their male counterparts did not show these risk alterations (p = 0.445/p = 0.822).

CONCLUSION

After acute SAH, female and male patients seem to show different age patterns for the risk of SV and DCI. Females aged between 55 and 74 years are at particular risk of vasospasm-related SAH complications, possibly due to onset of menopause.

CLINICAL TRIAL REGISTRATION NUMBER

DRKS, Unique identifier: DRKS00008749.

3,4-Dihydroxyphenylethanol alleviates early brain injury by modulating oxidative stress and Akt and nuclear factor-κB pathways in a rat model of subarachnoid hemorrhage

3,4-Dihydroxyphenylethanol (DOPET) is a naturally occurring polyphenolic compound, present in olive oil and in the wastewater generated during olive oil processing. DOPET has various biological and pharmacological activities, including anticancer, antibacterial and anti-inflammatory effects. This study was designed to determine whether DOPET alleviates early brain injury (EBI) associated with subarachnoid hemorrhage (SAH) through suppression of oxidative stress and Akt and nuclear factor (NF)-κB pathways. Rats were randomly divided into the following groups: Sham group, SAH group, SAH + vehicle group and SAH + DOPET group. Mortality, blood-brain barrier (BBB) permeability and brain water content were assessed. Oxidative stress, Akt, NF-κB p65 and caspase-3 assays were also performed. DOPET induced a reduction in brain water content, and decreased the BBB permeability of SAH model rats. Furthermore, DOPET effectively controlled oxidative stress, NF-κB p65 and caspase-3 levels, in addition to significantly increasing Akt levels in the cortex following SAH. These results provide evidence that DOPET attenuates apoptosis in a rat SAH model through modulating oxidative stress and Akt and NF-κB signaling pathways.

Inducible nitric oxide synthase (NOS-2) in subarachnoid hemorrhage: Regulatory mechanisms and therapeutic implications

Aneurysmal subarachnoid hemorrhage (SAH) typically carries a poor prognosis. Growing evidence indicates that overabundant production of nitric oxide (NO) may be responsible for a large part of the secondary injury that follows SAH. Although SAH modulates the activity of all three isoforms of nitric oxide synthase (NOS), the inducible isoform, NOS-2, accounts for a majority of NO-mediated secondary injuries after SAH. Here, we review the indispensable physiological roles of NO that must be preserved, even while attempting to downmodulate the pathophysiologic effects of NO that are induced by SAH. We examine the effects of SAH on the function of the various NOS isoforms, with a particular focus on the pathological effects of NOS-2 and on the mechanisms responsible for its transcriptional upregulation. Finally, we review interventions to block NOS-2 upregulation or to counteract its effects, with an emphasis on the potential therapeutic strategies to improve outcomes in patients afflicted with SAH. There is still much to be learned regarding the apparently maladaptive response of NOS-2 and its harmful product NO in SAH. However, the available evidence points to crucial effects that, on balance, are adverse, making the NOS-2/NO/peroxynitrite axis an attractive therapeutic target in SAH.

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.

Neurovascular events after subarachnoid hemorrhage: focusing on subcellular organelles

Subarachnoid hemorrhage (SAH) is a devastating condition with high morbidity and mortality rates due to the lack of effective therapy. Early brain injury (EBI) and cerebral vasospasm (CVS) are the two most important pathophysiological mechanisms for brain injury and poor outcomes for patients with SAH. CVS has traditionally been considered the sole cause of delayed ischemic neurological deficits after SAH. However, the failure of antivasospastic therapy in patients with SAH supported changing the research target from CVS to other mechanisms. Currently, more attention has been focused on global brain injury within 3 days after ictus, designated as EBI. The dysfunction of subcellular organelles, such as endoplasmic reticulum stress, mitochondrial failure, and autophagy-lysosomal system activation, has developed during EBI and delayed brain injury after SAH. To our knowledge, there is a lack of review articles addressing the direction of organelle dysfunction after SAH. In this review, we discuss the roles of organelle dysfunction in the pathogenesis of SAH and present the opportunity to develop novel therapeutic strategies of SAH via modulating the functions of organelles.

Progesterone attenuates experimental subarachnoid hemorrhage-induced vasospasm by upregulation of endothelial nitric oxide synthase via Akt signaling pathway

Cerebral vasospasm is the leading cause of mortality and morbidity in patients after aneurysmal subarachnoid hemorrhage (SAH). However, the mechanism and adequate treatment of vasospasm are still elusive. In the present study, we evaluate the effect and possible mechanism of progesterone on SAH-induced vasospasm in a two-hemorrhage rodent model of SAH. Progesterone (8 mg/kg) was subcutaneously injected in ovariectomized female Sprague-Dawley rats one hour after SAH induction. The degree of vasospasm was determined by averaging the cross-sectional areas of basilar artery 7 days after first SAH. Expressions of endothelial nitric oxide synthase (eNOS) and phosphorylated Akt (phospho-Akt) in basilar arteries were evaluated. Prior to perfusion fixation, there were no significant differences among the control and treated groups in physiological parameters recorded. Progesterone treatment significantly (P < 0.01) attenuated SAH-induced vasospasm. The SAH-induced suppression of eNOS protein and phospho-Akt were relieved by progesterone treatment. This result further confirmed that progesterone is effective in preventing SAH-induced vasospasm. The beneficial effect of progesterone might be in part related to upregulation of expression of eNOS via Akt signaling pathway after SAH. Progesterone holds therapeutic promise in the treatment of cerebral vasospasm following SAH.

Therapeutic implications of estrogen for cerebral vasospasm and delayed cerebral ischemia induced by aneurysmal subarachnoid hemorrhage

Cerebral vasospasm (CV) remains the leading cause of delayed morbidity and mortality following aneurysmal subarachnoid hemorrhage (SAH). However, increasing evidence supports etiologies of delayed cerebral ischemia (DCI) other than CV. Estrogen, specifically 17 β -estradiol (E2), has potential therapeutic implications for ameliorating the delayed neurological deterioration which follows aneurysmal SAH. We review the causes of CV and DCI and examine the evidence for E2-mediated vasodilation and neuroprotection. E2 potentiates vasodilation by activating endothelial nitric oxide synthase (eNOS), preventing increased inducible NOS (iNOS) activity caused by SAH, and decreasing endothelin-1 production. E2 provides neuroprotection by increasing thioredoxin expression, decreasing c-Jun N-terminal kinase activity, increasing neuroglobin levels, preventing SAH-induced suppression of the Akt signaling pathway, and upregulating the expression of adenosine A2a receptor. The net effect of E2 modulation of these various effectors is the promotion of neuronal survival, inhibition of apoptosis, and decreased oxidative damage and inflammation. E2 is a potentially potent therapeutic tool for improving outcomes related to post-SAH CV and DCI. However, clinical evidence supporting its benefits remains lacking. Given the promising preclinical data available, further studies utilizing E2 for the treatment of patients with ruptured intracranial aneurysms appear warranted.

Estradiol reduces ferrous citrate complex-induced NOS2 up-regulation in cerebral endothelial cells by interfering the nuclear factor kappa B transactivation through an estrogen receptor β-mediated pathway

Hemorrhagic stroke caused leakage of red blood cells which converts to hemoglobin, heme, and iron accumulated at the lesions. High concentration of ferrous iron from subarachnoid hemorrhage (SAH) induced cerebral vasospasm. Using the two-hemorrhage SAH model in rats, we previously demonstrated that estradiol (E2) significantly attenuated the SAH-induced vasospasm by inhibiting the NOS2 expression. Adding ferrous citrate (FC) complexes to the primary cultured mouse cerebral endothelial cells (CEC) to mimic the SAH conditions, we also showed that FC up-regulates NOS2 through nuclear translocation of NFκB induced by free radicals generation. Here, we further studied the molecular mechanism underlying E2-mediated reduction of the FC-induced up-regulation of NOS2. Treatment with E2 (100 nM) reduced the FC (100 µM)-induced increases of free radical generation and the levels of NOS2 mRNA and protein in the CEC. Moreover, E2 also prevented the FC-induced increases of IκBα phosphorylation, NFκB nuclear translocation, NFκB binding onto the NOS2 promoter, and the NOS2 promoter luciferase activity. However, knock-down the estrogen receptor β (ERβ), but not ERα, abolished the E2-mediated prevention on the FC-induced increases of NOS2 mRNA and protein. The data from the present study suggest that E2 inhibited NOS2 gene expression by interfering with NFκB nuclear translocation and NFκB binding onto the NOS2 through an ERβ-mediated pathway. Our results provide the molecular basis for designing the applicable therapeutic or preventive strategies in the treatment SAH patients.

17β-Estradiol attenuates secondary injury through activation of Akt signaling via estrogen receptor alpha in rat brain following subarachnoid hemorrhage

BACKGROUND

Apoptosis is implicated in vasospasm and the long-term sequelae of subarachnoid hemorrhage (SAH). This study tested the hypothesis that attenuation of SAH-induced apoptosis after 17β-estradiol (E2) treatment is associated with an increase in phosphorylation of Akt via estrogen receptor-α (ER-α) in rats.

MATERIALS AND METHODS

We examined the expression of phospho-Akt, ERα and ERβ, and apoptosis in cerebral cortex, hippocampus, and dentate gyrus in a two-hemorrhage SAH model in rats. We subcutaneously implanted other rats with a silicone rubber tube containing E2; they received daily injections of nonselective estrogen receptor antagonist (ICI 182,780), selective ERα-selective antagonist (methyl-piperidino-pyrazole), or ERβ-selective antagonist (R,R-tetrahydrochrysene) after the first hemorrhage.

RESULTS

At 7 d after the first SAH, protein levels of phospho-Akt and ERα were significantly decreased and caspase-3 was significantly increased in the dentate gyrus. The cell death assay revealed that DNA fragmentation was significantly increased in the dentate gyrus. Those actions were reversed by E2 and blocked by ICI 182,780 and methyl-piperidino-pyrazole, but not R,R-tetrahydrochrysene. However, there were no significant changes in the expression of the protein levels of phospho-Akt, ERα, ERβ, and caspase-3, and DNA fragmentation after SAH.

CONCLUSIONS

The present study shows that a beneficial effect of E2 in attenuating SAH-induced apoptosis is associated with activation of the expression of phospho-Akt and ERα, and alteration in caspase-3 protein expression via an ERα-dependent mechanism in the dentate gyrus. These data support further the investigation of E2 in the treatment of SAH in humans.

Purine anti-metabolite attenuates nuclear factor κB and related pro-inflammatory cytokines in experimental vasospasm

BACKGROUND

Increased nuclear factor κB (NF-κB) bioexpression, as well as TNF-α, IL-1β and IL-6 levels, were observed after aneurysmal subarachnoid hemorrhage (SAH). It is of interest to investigate the effect of 6-mercaptopurine (6-mp) on cytokines/NF-κB in this SAH model.

MATERIALS AND METHODS

A rodent double-hemorrhage SAH model was employed. Serum and cerebrospinal fluid (CSF) samples were collected to examine IL-1, IL-6 and TNF-α levels. NF-κB subunit p65 and its inhibitor of nuclear factor κB (IκB) were examined (by Western blot). TNF-α was used to induce the phosphorylation of IκB in the presence or absence of 6-mp.

RESULTS

Nuclear NF-κB subunit p65/IκB kinase in the basilar artery was over-expressed, and cytokines was notably increased in the SAH groups, compared with the controls (P < 0.01). In the 6-mp SAH group, obvious reduction was observed in NF-κB subunit p65 (nuclei) (P < 0.01). Treatment with 6-mp significantly reduced IL-1β and TNF-α levels to those of the healthy control. 6-Mercaptopurine also significantly increased the level of IκB in the TNF-α-stimulated SAH rats.

CONCLUSIONS

Through inhibiting IκB bioexpression, 6-mp decreases NF-κB-related IL-1β, IL-6, and TNF-α in the presence of SAH. The study suggests 6-mp exerts vascular anti-inflammatory properties through inhibiting IκB kinase and subsequently blocks bio-activation of NF-κB and related cytokines, which may contribute to its antivasospastic effect in animals subjected to SAH.

Ferrous citrate up-regulates the NOS2 through nuclear translocation of NFκB induced by free radicals generation in mouse cerebral endothelial cells

Previous studies indicate that the inducible nitric oxide synthase 2 (NOS2) of the brain vascular tissue in experimental subarachnoid hemorrhage (SAH) rats is a critical factor for inducing cerebral vasospasm. However, the underlying molecular mechanisms remain to be elucidated. Here, we applied ferrous citrate (FC) complexes to the primary cultured mouse cerebral endothelial cell (CEC) to mimic the SAH conditions and to address the issue how SAH-induced NOS2 up-regulation. Using immunocytochemical staining technique, we demonstrated that NOS2 was expressed in the cultured CEC. Treatment of the CEC with FC induced increases of the intracellular level of ROS, nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB) nuclear translocation as well as NFκB binding onto the NOS promoter, and the levels of NOS2 mRNA and protein. These effects were abolished by pre-treatment of the cell with N-Acetyl-Cysteine (NAC), a reactive oxygen species (ROS) scavenger. In the present study, two previously predicted NFκB binding sites were confirmed in the NOS2 promoter within the range of −1529 bp to −1516 bp and −1224 bp to −1210 bp. Interestingly, both NFκB binding sites are involved in the FC-activated NOS2 transcriptional activity; the binding site located at −1529 bp to −1516 bp played a greater role than the other binding site located at −1224 bp to −1210 bp in the mouse CEC. These findings highlight the molecular mechanism underlying FC-induced up-regulation of NOS2 in the mouse CEC.

The relationship between IL-6 in CSF and occurrence of vasospasm after subarachnoid hemorrhage

BACKGROUND

It is hypothesized that inflammatory response after subarachnoid hemorrhage (SAH) may play a relevant role in the development and maintenance of vasospasm. This research investigated the correlation between IL-6 in cerebrospinal fluid (CSF) after SAH and the occurrence of vasospasm.

METHODS

We analyzed both daily clinical manifestation and laboratory data of CSF in 46 patients who suffered from intracranial aneurismal subarachnoid hemorrhage during a period of 14 days, studied the relationship between the development of vasospasm and the quantities of the inflammatory factor, revealing potential power of IL-6 for predicting vasospasm detected by transcranial doppler (TCD).

RESULTS

The incidence of vasospasm developed in 43.5% of the patients, with a mean onset of 6.1±4.6 days after intracranial aneurysm treatment. Patients with vasospasm demonstrated statistically significant higher median values of IL-6CSF on Day 1, 2, 3, 5 and 7 (P<0.05). The cut-off value is settled in 400 pg/ml on Day 3 after treatment. On the other hand, gender, Hunt & Hess scale (H&H) and Fisher scale of CT after SAH were proved to be the correlation factor with vasospasm.

CONCLUSION

IL-6CSF seems to be a reliable early marker for predicting vasospasm after subarachnoid hemorrhage on Days 3 after treatment before clinical onset.

Advances in experimental subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) remains to be a devastating disease with high mortality and morbidity. Two major areas are becoming the focus of the research interest of SAH: these are cerebral vasospasm (CVS) and early brain injury (EBI). This mini review will provide a broad summary of the major advances in experimental SAH during the last 3 years. Treatments interfering with nitric oxide (NO)- or endothelin-pathways continue to show antispasmotic effects in experimental SAH. HIF 1 may play both a detrimental and beneficial role in the setting of SAH, depending on its activation stage. Inflammation and oxidative stress contribute to the pathophysiology of both CVS and EBI. Apoptosis, a major component of EBI after SAH, also underlie the etiology of CVS. Since we recognize now that CVS and EBI are the two major contributors to the significant mortality and morbidity associated with SAH, ongoing research will continue to elucidate the underlying pathophysiological pathways and treatment strategies targeting both CVS and EBI may be more successful and improve outcome of patients with SAH.

Attenuation of subarachnoid hemorrhage-induced apoptotic cell death with 17 beta-estradiol. Laboratory investigation

OBJECT

Apoptosis is implicated in vasospasm and long-term sequelae of subarachnoid hemorrhage (SAH). The authors observed that 17beta-estradiol (E2) can attenuate cerebral vasospasm, lower endothelin-1 production, and preserve normal endothelial nitric oxide synthase expression by reduction of inducible NO synthase expression in experimental SAH. The authors investigated the potential antiapoptotic effects of E2 in an experimental rat model of SAH.

METHODS

The authors examined the antiapoptotic effects of E2 in a double-hemorrhage SAH model in male Sprague-Dawley rats. The rats underwent subcutaneous implantation of a Silastic tube containing corn oil either with or without E2, and some E2-treated animals also received ICI 182,780 (a nonselective estrogen receptor [ER] antagonist) for 7 days after SAH. The degree of vasospasm was determined by averaging the cross-sectional areas of the basilar artery 7 days after SAH. The expression of apoptotic indicators, including TNF-alpha, caspase 3, Bcl-2, Bax, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling (TUNEL), and cell death assays were used for detection of apoptosis.

RESULTS

Treatment with E2 significantly attenuated SAH-induced vasospasm. Seven days after the induction of SAH, positive TUNEL-staining was seen, and DNA fragmentation was increased in the dentate gyrus. Increased TNF-alpha and cleaved caspase-3 protein expression and decreased Bcl-2 protein expression in the dentate gyrus were also observed. These changes were reversed with E2-treatment but not in the presence of ICI 182,780. However, the expression of Bax did not change after SAH either with or without E2 treatment.

CONCLUSIONS

The authors found that E2 appears to confer an antiapoptotic effect that reduces secondary brain injury after SAH via estrogen receptor-dependent mechanisms. This finding provides support for possible future applications of E2 treatment for the reduction of secondary injury after SAH in patients.

Attenuation of cerebral vasospasm and secondary injury by 17beta-estradiol following experimental subarachnoid hemorrhage

OBJECT

Cerebral vasospasm remains a major complication in patients who have suffered a subarachnoid hemorrhage (SAH). Previous studies have shown that 17beta-estradiol (E2) attenuates experimental SAH-induced cerebral vasospasm. Moreover, E2 has been shown to reduce neuronal apoptosis and secondary injury following cerebral ischemia. Adenosine A1 receptor (AR-A1) expression is increased following ischemia and may represent an endogenous neuroprotective effect. This study was designed to evaluate the efficacy of E2 in preventing cerebral vasospasm and reducing secondary injury, as evidenced by DNA fragmentation and AR-A1 expression, following SAH.

METHODS

A double-hemorrhage model of SAH in rats was used, and the degree of vasospasm was determined by averaging the cross-sectional areas of the basilar artery 7 days after the first SAH. A cell death assay was used to detect apoptosis. Changes in the protein expression of AR-A1 in the cerebral cortex, hippocampus, and dentate gyrus were compared with levels in normal controls and E2-treated groups (subcutaneous E2, 0.3 mg/ml).

RESULTS

The administration of E2 prevented vasospasm (p < 0.05). Seven days after the first SAH, DNA fragmentation and protein levels of AR-A1 were significantly increased in the dentate gyrus. The E2 treatment decreased DNA fragmentation and prevented the increase in AR-A1 expression in the dentate gyrus. There were no significant changes in DNA fragmentation and the expression of AR-A1 after SAH in the cerebral cortex and hippocampus in the animals in the control and E2-treated groups.

CONCLUSIONS

The E2 was effective in attenuating SAH-induced cerebral vasospasm, decreasing apoptosis in the dentate gyrus, and reducing the expression of AR-A1 in the dentate gyrus after SAH. Interestingly, E2 appears to effectively prevent cerebral vasospasm subsequent to SAH as well as attenuate secondary injury by reducing both apoptosis and a compensatory increase in AR-A1 expression in the dentate gyrus.

17Beta-estradiol activates adenosine A(2a) receptor after subarachnoid hemorrhage

BACKGROUND

Our previous study showed that 17beta-estradiol (E2) and an adenosine A(2A) receptor (AR-A(2A)) agonist could attenuate subarachnoid hemorrhage (SAH)-induced cerebral vasospasm via preventing the augmentation of iNOS expression and preserving the normal eNOS expression. This study tests the hypothesis that E2 attenuates SAH-induced vasospasm and apoptosis by activating adenosine AR-A(2A) and extracellular signal-regulated kinase 1 and 2 (ERK1/2), and by altering antiapoptotic and proapoptotic protein expression (Bcl-2 and Bax, respectively).

MATERIALS AND METHODS

The two-hemorrhage SAH model in rat was used. Animals were treated with E2 with or without a nonselective estrogen receptor (ER) antagonist (ICI182,780). The cross sectional areas of the basilar artery and terminal dUTP nick-end labeling (TUNEL) were used to determine the degree of vasospasm and apoptosis, respectively. The expressions of Bcl-2, Bax, AR-A(2A), and ERK1/2 in the cerebral cortex, hippocampus, and dentate gyrus were investigated.

RESULTS

E2 significantly attenuated vasospasm. Seven days after the first SAH, TUNEL scores were significantly increased, and protein levels of AR-A(2A), ERK1/2, and Bcl-2 were significantly decreased in the dentate gyrus only but not in the cortex and hippocampus. These changes were reversed by E2 while ICI182,780 abrogated the antiapoptotic and anti-spastic effects of E2. The expression of Bax did not change in the dentate gyrus after SAH with or without treatment.

CONCLUSIONS

The down-regulated AR-A(2A) and ERK may play a role in vasospasm and apoptosis after SAH. The beneficial effect of E2 in the attenuating SAH-induced vasospasm and apoptosis may be due to an increased expression of AR-A(2A) and ERK via ER-dependent mechanisms. These data may support further investigation of E2 in the treatment of SAH in humans.

Gender and the injured brain

Anesthesiologists are frequently confronted with patients who are at risk for neurological complications due to perioperative stroke or prior traumatic brain injury. In this review, we address the growing and fascinating body of data that suggests gender and sex steroids influence the pathophysiology of injury and outcome for these patients. Cerebral ischemia, traumatic brain injury, and epilepsy are reviewed in the context of potential sex differences in mechanisms and outcomes of brain injury and the role of estrogen, progesterone, and androgens in shaping these processes. Lastly, implications for current and future perioperative and intensive care are identified.

Upregulation of estrogen receptor α and mediation of 17β-estradiol vasoprotective effects via estrogen receptor α in basilar arteries in rats after experimental subarachnoid hemorrhage

Object

The authors previously demonstrated that 17β-estradiol benzoate (E2) treatment prevents subarachnoid hemorrhage (SAH)–induced cerebral vasospasm and preserves endothelial nitric oxide synthase (eNOS) in male rats. Changes in the expression of estrogen receptor (ER) subtypes ERα and -β and their roles in the E2-mediated preservation of eNOS in SAH remain unknown. In the present study the effects of SAH on the expression of ERα and -β in the cerebral arteries were clarified, and the receptor roles in the E2-mediated preservation of eNOS expression in SAH were differentiated.

Methods

A 2-hemorrhage SAH model was induced by 2 autologous blood injections into the cisterna magna of adult male rats. The effect of SAH on ERα and -β expression was evaluated. Other rats subcutaneously received implanted Silastic tubes containing corn oil with E2 and daily injections of various doses of an ERα- (methyl-piperidinopyrazole [MPP]) or ERβ-selective antagonist (R,R-tetrahydrochrysene) after the first hemorrhage. The protein levels of ERα, ERβ, eNOS, and inducible nitric oxide synthase (iNOS) from basilar arteries were examined using Western blot analysis, and their mRNAs were evaluated by reverse transcription–polymerase chain reaction.

Results

The ERα but not the ERβ was upregulated in the basilar artery after SAH. Treatment with MPP eliminated E2-mediated effects in SAH, relieved cerebral vasospasm, preserved eNOS expression, and suppressed iNOS expression.

Conclusions

Estrogen receptor α is upregulated in the basilar artery after SAH. Note that E2 exerts its protective effects through ERα-dependent pathways to relieve cerebral vasospasm and preserve eNOS expression. A selective ERα agonist may be the drug of choice for the treatment of patients with SAH.

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.

Effect of raloxifene on cerebral vasospasm following experimental subarachnoid hemorrhage in rats

The effect of raloxifene on cerebral vasospasm following experimental subarachnoid hemorrhage (SAH) was investigated in a rat model. Seven groups of seven rats underwent no SAH, no treatment; SAH only; SAH plus vehicle; SAH plus 3 days intraperitoneal raloxifene treatment; SAH plus 4 days intraperitoneal raloxifene treatment; SAH plus 3 days intrathecal raloxifene treatment; and SAH plus 4 days intrathecal raloxifene treatment. The basilar artery cross-sectional areas were measured at 72 or 96 hours following SAH. The results showed raloxifene decreased SAH-induced cerebral vasospasm in all treatment groups, and suggested no difference between intraperitoneal and intrathecal application, or between 3 days and 4 days of raloxifene treatment. The present study demonstrates that raloxifene is a potential therapeutic agent against cerebral vasospasm after SAH.

Redox features of the cell: a gender perspective

Reactive oxygen and nitrogen species have been implicated in diverse subcellular activities, including cell proliferation,differentiation and, in some instances, cell injury and death. The implications of reactive species inhuman pathology have also been studied in detail. However, although the role of free radicals in the pathogenesis of human diseases has been extensively analyzed in different systems (i.e., in vitro, ex vivo, and in vivo),it is still far from elucidated. In particular, the possible role of gender 4 differences in human pathophysiology associated with reactive species is a promising new field of investigation. Although the complex scenario this presents is still incomplete, important gender-associated "redox features" of cells have already been described in the literature. Here we summarize the different aspects of redox-associated molecules and enzymes in regard to gender differences in terms of the intracellular production and biochemical activity of reactive species. These are often associated with the pathogenetic mechanisms underlying several human morbidities(e.g., degenerative diseases) and can represent a specific target for new pharmacologic strategies. Gender differences may thus pose an important challenge for future studies aimed at the clinical management of diseases characterized by a redox imbalance.