Aminoguanidine inhibition of iNOS activity ameliorates cerebral vasospasm after subarachnoid hemorrhage in rabbits via restoration of dysfunctional endothelial cells

Exploring medical gas therapy in hemorrhagic stroke treatment: A narrative review

Hemorrhagic stroke (HS) is a neurological disorder caused by the rupture of cerebral blood vessels, resulting in blood seeping into the brain parenchyma and causing varying degrees of neurological impairment, including intracerebral hemorrhage (ICH) and subarachnoid hemorrhage (SAH). Current treatment methods mainly include hematoma evacuation surgery and conservative treatment. However, these methods have limited efficacy in enhancing neurological function and prognosis. The current challenge in treating HS lies in inhibiting the occurrence and progression of secondary brain damage after bleeding, which is a key factor affecting the prognosis of HS patients. Studies have shown that medical gas therapy is gaining more attention and has demonstrated various levels of neuroprotective effects on central nervous system disorders, such as hyperbaric oxygen, hydrogen sulfide, nitric oxide, carbon monoxide, and other inhalable gas molecules. These medical gas molecules primarily improve brain tissue damage and neurological dysfunction by regulating inflammation, oxidative stress, apoptosis, and other processes. However, many of these medical gasses also possess neurotoxic properties. Therefore, the use of medical gases in HS deserves further exploration and research. In this review, we will elucidate the therapeutic effects and study the advances in medical gas molecules in HS.

Isoflurane Conditioning-Induced Delayed Cerebral Ischemia Protection in Subarachnoid Hemorrhage-Role of Inducible Nitric Oxide Synthase

Background Recent evidence implicates inflammation as a key driver in delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage (SAH). Inducible nitric oxide synthase (iNOS) is one of the known major mediators of inflammation. We previously showed that an inhalational anesthetic, isoflurane, provides strong protection against delayed cerebral ischemia after SAH. Our current study aims to define the role of iNOS in isoflurane conditioning-induced protection against delayed cerebral ischemia in a mouse model of SAH. Methods and Results The experiments used 10- to 14-week-old male wild-type (C57BL/6) and iNOS global knockout mice. Anesthetic conditioning was initiated 1 hour after SAH with isoflurane 2% for 1 hour. Isoflurane-induced changes in iNOS expression were measured. N-(3-(aminomethyl) benzyl) acetamidine, a highly selective iNOS inhibitor, was injected intraperitoneally immediately after SAH and then daily. Vasospasm, microvessel thrombosis, and neurological assessment was performed. Data were analyzed by 1-way ANOVA and 2-way repeated measures ANOVA followed by Student Newman Keuls comparison test. Statistical significance was set at P<0.05. Isoflurane conditioning downregulated iNOS expression in naïve and SAH mice. N-(3-(aminomethyl) benzyl) acetamidine attenuated large artery vasospasm and microvessel thrombosis and improved neurological deficits in wild-type animals. iNOS knockout mice were significantly resistant to vasospasm, microvessel thrombosis, and neurological deficits induced by SAH. Combining isoflurane with N-(3-(aminomethyl) benzyl) acetamidine did not offer extra protection, nor did treating iNOS knockout mice with isoflurane. Conclusions Isoflurane conditioning-induced delayed cerebral ischemia protection appears to be mediated by downregulating iNOS. iNOS is a potential therapeutic target to improve outcomes after SAH.

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.

The Roles of Nitric Oxide Synthase/Nitric Oxide Pathway in the Pathology of Vascular Dementia and Related Therapeutic Approaches

Vascular dementia (VaD) is the second most common form of dementia worldwide. It is caused by cerebrovascular disease, and patients often show severe impairments of advanced cognitive abilities. Nitric oxide synthase (NOS) and nitric oxide (NO) play vital roles in the pathogenesis of VaD. The functions of NO are determined by its concentration and bioavailability, which are regulated by NOS activity. The activities of different NOS subtypes in the brain are partitioned. Pathologically, endothelial NOS is inactivated, which causes insufficient NO production and aggravates oxidative stress before inducing cerebrovascular endothelial dysfunction, while neuronal NOS is overactive and can produce excessive NO to cause neurotoxicity. Meanwhile, inflammation stimulates the massive expression of inducible NOS, which also produces excessive NO and then induces neuroinflammation. The vicious circle of these kinds of damage having impacts on each other finally leads to VaD. This review summarizes the roles of the NOS/NO pathway in the pathology of VaD and also proposes some potential therapeutic methods that target this pathway in the hope of inspiring novel ideas for VaD therapeutic approaches.

Aminoguanidine inhibits IL-1β-induced protein expression of iNOS and COX-2 by blocking the NF-κB signaling pathway in rat articular chondrocytes

Osteoarthritis is a chronic joint disease which has a serious impact on the health and quality of life of affected humans and animals. As an inhibitor of inducible nitric oxide synthase (iNOS), aminoguanidine (AG) displays anti-inflammatory effects. The purpose of the present study was to investigate the effect of AG on the expression of iNOS and cyclooxygenase-2 (COX-2), and the activity of the NF-κB signaling pathway in rat chondrocytes stimulated by interleukin-1β (IL-1β). The viability of chondrocytes treated with AG (0.3, 1 or 3 mM) alone was determined using a Cell Counting Kit-8 assay. Subsequently, the chondrocytes were treated with either 10 ng/ml IL-1β alone, or co-treated with increasing concentrations of AG (0.3, 1 or 3 mM) and 10 ng/ml IL-1β. The protein levels of COX-2, iNOS, phosphorylated (p)-p65, p65, p-NF-κβ inhibitor α (IκBα), IκBα, p-inhibitor of NF-κβ-β (IKKβ) and IKKβ were evaluated by western blotting. NF-κB translocation was determined by immunofluorescence analysis. Western blotting and reverse transcription-quantitative PCR were used to detect expression levels of relevant proteins/genes. The results suggested that the inhibitory effect of AG on the protein and gene expression levels of iNOS and COX-2 in IL-1β-treated chondrocytes was dose-dependent. In addition, AG decreased the level of phosphorylation of IKKβ, IκBα and NF-κB p65, the degradation of IKKβ, IκBα and p65, and the translocation of NF-κB in IL-1β-stimulated chondrocytes. The most significant inhibitory effect of AG was observed at a concentration of 1 mM. Therefore, the present study suggested that AG may serve as a potential agent to reduce the inflammatory response of chondrocytes stimulated by IL-1β.

Mechanisms of neuroinflammation and inflammatory mediators involved in brain injury following subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) is a devastating cerebrovascular disorder. Neuroinflammation is a critical cause of brain injury following SAH in both acute and chronic phases. While accumulating evidence has shown that therapies targeting neuroinflammation exerted beneficial effects in experimental SAH, there is little clinical evidence. One of the factors making neuroinflammation complicated is that inflammatory signaling pathways and mediators act as protective or detrimental responses at different phases. In addition, biomarkers to detect neuroinflammation are little known in clinical settings. In this review, first, we discuss how the inflammatory signaling pathways contribute to brain injury and other secondary pathophysiological changes in SAH. Damage-associated molecular patterns arising from mechanical stress, transient global cerebral ischemia, red blood cell breakdown and delayed cerebral ischemia following SAH trigger to activate pattern recognition receptors (PRRs) such as Toll-like receptors, nucleotide-binding oligomerization domain-like receptors, and receptors for advanced glycation end products. Most of PRRs activate common downstream signaling transcriptional factor nuclear factor-κΒ and mitogen-activated protein kinases, releasing pro-inflammatory mediators and cytokines. Next, we focus on how pro-inflammatory substances play a role during the course of SAH. Finally, we highlight an important inducer of neuroinflammation, matricellular protein (MCP). MCPs are a component of extracellular matrix and exert beneficial and harmful effects through binding to receptors, other matrix proteins, growth factors, and cytokines. Treatment targeting MCPs is being proved efficacious in pre-clinical models for preventing brain injury including neuroinflammation in SAH. In addition, MCPs may be a candidate of biomarkers predicting brain injury following SAH in clinical settings.

The role of nitric oxide in stroke

Stroke is considered to be an acute cerebrovascular disease, including ischemic stroke and hemorrhagic stroke. The high incidence and poor prognosis of stroke suggest that it is a highly disabling and highly lethal disease which can pose a serious threat to human health. Nitric oxide (NO), a common gas in nature, which is often thought as a toxic gas, because of its intimate relationship with the pathological processes of many diseases, especially in the regulation of blood flow and cell inflammation. However, recent years have witnessed an increased interest that NO plays a significant and positive role in stroke as an essential gas signal molecule. In view of the fact that the neuroprotective effect of NO is closely related to its concentration, cell type and time, only in the appropriate circumstances can NO play a protective effect. The purpose of this review is to summarize the roles of NO in ischemic stroke and hemorrhagic stroke.

Pentoxifylline Alleviates Early Brain Injury in a Rat Model of Subarachnoid Hemorrhage

BACKGROUND

Subarachnoid hemorrhage (SAH) is a severe cerebrovascular disease frequently caused by ruptured aneurysms. Early brain injury (EBI) is the primary cause of morbidity and mortality in patients diagnosed with SAH and is associated with increased intracranial pressure, decreased cerebral blood flow and cerebral ischemia. Pentoxifylline (PTX) is a methylxanthine derivative clinically proven to improve perfusion in the peripheral microcirculation and has been shown to have neuroprotective effects in brain trauma and global cerebral ischemia in experimental animal models. This study aimed to determine the effect of PTX in experimental SAH, which has not been investigated yet.

METHODS

An experimental SAH model was induced in male Wistar rats by autologous blood injection into the prechiasmatic cistern, and PTX was injected intraperitoneally immediately after SAH. The effects of PTX were evaluated 24 h after SAH via assessing the cerebral ultrastructure via transmission electron microscopy (TEM). Brain edema, blood-brain barrier (BBB) permeability, red blood cell deformability, tumor necrosis factor-alpha (TNF-alpha), nitrite-nitrate levels and apoptotic neuron death were also determined 24 h after SAH. The BBB permeability was measured by Evans blue (EB) extravasation, erythrocyte deformability was determined by filtration technique, and TNF-alpha and reactive nitrogen metobolites were analyzed in brain tissue by ELISA and spectral analysis, respectively. Apoptotic neurons were determined in brain sections by cleaved caspase-3 immunohistochemical analysis, and expression intensity was quantified using image J software.

RESULTS

Cerebral ultrastructure in SAH group animals revealed intense perivascular edema and distortion in the astrocyte foot processes. PTX treatment attenuated structural deterioration due to SAH. Brain water content, BBB permeability, TNF-alpha, nitrite-nitrate levels and apoptotic neuronal death were significantly increased 24 h after SAH and were significantly alleviated by PTX treatment. There was no significant change in red cell deformability after SAH.

CONCLUSIONS

Our results show that PTX reduces brain edema, BBB permeability, TNF-alpha expression, reactive nitrogen metobolites and apopotosis in experimental SAH. Based on our findings we suggest that PTX exerts neuroprotection against SAH-induced EBI, which might be associated with the inhibition of inflammation and apoptotic neuronal cell death.

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.

Neuroprotective Effect of Radix Trichosanthis Saponins on Subarachnoid Hemorrhage

Redox homeostasis has been implicated in subarachnoid hemorrhage (SAH). As a result, antioxidants and/or free radical scavengers have become an important therapeutic modality. Considering that radix trichosanthis (RT) saponins exhibited strong antioxidant ability both in vivo and in vitro, the present study aimed to reveal whether the neuroprotective activities of RT saponins were mediated by p38/p53 signal pathway after SAH. An established SAH model was used and superoxide dismutase (SOD), malondialdehyde (MDA), induced nitric oxide synthase (iNOS), nitric oxide (NO), lactate dehydrogenase (LDH), p-p38, and p53 activation were detected after 48 h of SAH. The results showed that RT saponins inhibited iNOS expression to restore NO to basal level. Moreover, compared with Cu/Zn-SOD, RT saponins (2 mg/kg/d dosage) significantly increased Mn-SOD activity after SAH. Accompanied with lowered NO and elevated SOD, decreased p38 phosphorylation and p53 activities were observed, especially for RT saponins at 2 mg/kg/d dosage. In this setting, the neurological outcome was also improved with less neuronal cells damage after RT saponins pretreatment. Our findings demonstrated the beneficial effects of RT saponins in enhancing neuroprotective effects by deducing iNOS activity, normalizing SOD level, and inhibiting p-p38 and p53 expression, hence offering significant therapeutic implications for SAH.

Expression signatures of long non-coding RNAs in early brain injury following experimental subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) is an important cause of mortality in stroke patients. Long non-coding RNAs (LncRNAs) have important functions in brain disease, however their expression profiles in SAH remain to be elucidated. The present study aimed to investigate the expression signatures of LncRNAs and mRNAs in early brain injury (EBI) following SAH in a rat model. Male Wistar rats were randomly divided into an SAH group and a sham operation group. The expression signatures of the LncRNAs and mRNAs in the temporal lobe cortex were investigated using a rat LncRNAs array following experimental SAH. The results revealed that there were 144 downregulated and 64 upregulated LncRNAs and 181 downregulated and 221 upregulated mRNAs following SAH. Additionally, two upregulated (BC092207, MRuc008hvl) and three downregulated (XR_006756, MRAK038897, MRAK017168) LncRNAs were confirmed using reverse transcription quantitative polymerase chain reaction. The differentially expressed mRNAs were further analyzed using the Gene Ontology and the Kyoto Encyclopedia of Genes and Genomes (KEGG) databases. The pathway analysis results provided by the KEGG database indicated that eight pathways associated with inflammation were involved in EBI following SAH. In conclusion, these results demonstrated that the expression profiles of the LncRNAs and mRNAs were significantly different between the SAH-induced EBI group and the sham operation group. These differently expressed LncRNAs may be important in EBI following SAH.

The rabbit shunt model of subarachnoid haemorrhage

Aneurysmal subarachnoid haemorrhage (SAH) is a disease with devastating complications that leads to stroke, permanent neurological deficits and death. Clinical and ex-perimental work has demonstrated the importance of the contribution of delayed cerebral vasospasm (DCVS) indepen-dent early events to mortality, morbidity and functional out-come after SAH. In order to elucidate processes involved in early brain injury (EBI), animal models that reflect acute events of aneurysmal bleeding, such as increase in intracranial pressure (ICP) and decrease in cerebral perfusion pressure, are needed. In the presented arterial shunt model, bleeding is initially driven by the pressure gradient between mean arterial blood pressure and ICP. SAH dynamics (flow rate, volume and duration) depend on physiological reactions and local anatomical intrathecal (cistern) conditions. During SAH, ICP reaches a plateau close to diastolic arterial blood pressure and the blood flow stops. Historical background, anaesthesia, perioperative care and monitoring, SAH induction, technical considerations and advantages and limitations of the rabbit blood shunt SAH model are discussed in detail. Awareness of technical details, physiological characteristics and appropriate monitoring methods guarantees successful implementation of the rabbit blood shunt model and allows the study of both EBI and DCVS after SAH.

Blood pressure changes after aneurysmal subarachnoid hemorrhage and their relationship to cerebral vasospasm and clinical outcome

OBJECTIVE

Cerebral vasospasm (VS) and resulting delayed ischemic brain injury constitute the most severe secondary complication after subarachnoid hemorrhage (SAH). Identification of early clinical predictors of developing vasospasm and poor outcome has remained a major challenge in neurointensive care medicine. Aim of the present study was analyze the relevance of spontaneous changes in blood pressures and their predictive value for predicting vasospasm as well as adverse clinical outcome.

METHODS

98 aneurysmal SAH patients were analyzed retrospectively. Patients were divided into two study groups: (1) VS+ (developing VS) and (2) VS- (not developing VS). Repeat-angiography was routinely performed on day 8 after SAH or earlier if clinical signs were suggestive for overt vasospasm. Systolic, diastolic and mean blood pressures were averaged hourly and plotted over time. Secondly, blood pressure (BP)-progression was analyzed with respect to clinical outcomes as assessed by the Glasgow outcome scale.

RESULTS

Mean, systolic, and diastolic blood pressure values progressed in both VS- and VS+ cohorts over time. However, as early as 4 days after SAH a significant dissociation of RR curves was observed between the groups with patients in the VS+ group displaying a significantly higher slope coefficient of blood pressure elevation. An increase of mean arterial pressure >20% within the first 4 days was predictive of developing vasospasm. Elevation of mean arterial blood pressure in the VS+ group was mainly attributable to changes in diastolic pressure. Elevation of mean arterial blood pressure >25% within the first week after SAH was associated with unfavorable outcome.

CONCLUSIONS

SAH leads to spontaneous and progressive elevations in mean arterial blood pressure. Vasospasm might be anticipated by identifying early elevations of mean arterial blood pressure. Finally, spontaneous elevations of mean arterial blood pressure correlate with poorer outcomes.

Inducible nitric oxide synthase inhibition reverses pulmonary arterial dysfunction in lung transplantation

BACKGROUND

Ischemia-reperfusion injury (IRI) after lung transplantation remains a significant cause of morbidity and mortality. Lung IRI induces nitric oxide synthesis (iNOS) and reactive nitrogen species, decreasing nitric oxide bioavailability. We hypothesized that ischemia-induced iNOS intensifies with reperfusion and contributes to IRI-induced pulmonary arterial regulatory dysfunction, which may lead to early graft failure and cause pulmonary edema. The aim of this study was to determine whether ischemia-reperfusion alters inducible and endothelial nitric oxide synthase expression, potentially affecting pulmonary perfusion. We further evaluated the role of iNOS in post-transplantation pulmonary arterial disorder.

METHODS

We randomized 32 Sprague-Dawley rats into two groups. The control group was given a sham operation whilst the experimental group received orthotropic lung transplants with a modified three-cuff technique. Changes in lung iNOS, and endothelial nitric oxide synthase expression were measured after lung transplantation by enzyme-linked immunosorbent assay (ELISA). Vasoconstriction in response to exogenous phenylephrine and vasodilation in response to exogenous acetylcholine of pulmonary arterial rings were measured in vitro as a measure of vascular dysfunction. To elucidate the roles of iNOS in regulating vascular function, an iNOS activity inhibitor (N6-(1-iminoethyl)-L-lysine, L-NIL) was used to treat isolated arterial rings. In order to test whether iNOS inhibition has a therapeutic effect, we further used L-NIL to pre-treat transplanted lungs and then measured post-transplantation arterial responses.

RESULTS

Lung transplantation caused upregulation of iNOS expression. This was also accompanied by suppression of both vasoconstriction and vasodilation of arterial rings from transplanted lungs. Removal of endothelium did not interfere with the contraction of pulmonary arterial rings from transplanted lungs. In contrast, iNOS inhibition rescued the vasoconstriction response to exogenous phenylephrine of pulmonary arterial rings from transplanted lungs. In addition, lung transplantation led to suppression of PaO2/FiO2 ratio, increased intrapulmonary shunt (Q s/Q t), and increase of lung wet to dry ratio (W/D), malondialdehyde and myeloperoxidase levels, all of which were reversed upon iNOS inhibition. Furthermore, inhibition of iNOS significantly rescued vascular function and alleviated edema and inflammatory cell infiltration in the transplanted lung.

CONCLUSIONS

Our data suggest that lung transplantation causes upregulation of iNOS expression, and pulmonary vascular dysfunction. iNOS inhibition reverses the post-transplantational pulmonary vascular dysfunction.

Mangiferin prevents guinea pig tracheal contraction via activation of the nitric oxide-cyclic GMP pathway

Previous studies have described the antispasmodic effect of mangiferin, a natural glucoside xanthone (2-C-β-Dgluco-pyranosyl-1,3,6,7-tetrahydroxyxanthone) that is present in mango trees and other plants, but its mechanism of action remains unknown. The aim of this study was to examine the potential contribution of the nitric oxide-cyclic GMP pathway to the antispasmodic effect of mangiferin on isolated tracheal rings preparations. The functional effect of mangiferin on allergic and non-allergic contraction of guinea pig tracheal rings was assessed in conventional organ baths. Cultured tracheal rings were exposed to mangiferin or vehicle, and nitric oxide synthase (NOS) 3 and cyclic GMP (cGMP) levels were quantified using western blotting and enzyme immunoassays, respectively. Mangiferin (0.1–10 µM) inhibited tracheal contractions induced by distinct stimuli, such as allergen, histamine, 5-hydroxytryptamine or carbachol, in a concentration-dependent manner. Mangiferin also caused marked relaxation of tracheal rings that were precontracted by carbachol, suggesting that it has both anti-contraction and relaxant properties that are prevented by removing the epithelium. The effect of mangiferin was inhibited by the nitric oxide synthase inhibitor, Nω-nitro-L-arginine methyl ester (L-NAME) (100 µM), and the soluble guanylate cyclase inhibitor, 1H-[1], [2], [4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) (10 µM), but not the adenylate cyclase inhibitor, 9-(tetrahydro-2-furyl)adenine (SQ22536) (100 µM). The antispasmodic effect of mangiferin was also sensitive to K⁺ channel blockers, such as tetraethylammonium (TEA), glibenclamide and apamin. Furthermore, mangiferin inhibited Ca²⁺-induced contractions in K⁺ (60 mM)-depolarised tracheal rings preparations. In addition, mangiferin increased NOS3 protein levels and cGMP intracellular levels in cultured tracheal rings. Finally, mangiferin-induced increase in cGMP levels was abrogated by co-incubation with either ODQ or L-NAME. These data suggest that the antispasmodic effect of mangiferin is mediated by epithelium-nitric oxide- and cGMP-dependent mechanisms.

Genetic elimination of eNOS reduces secondary complications of experimental subarachnoid hemorrhage

Delayed complications of subarachnoid hemorrhage (SAH) such as angiographic vasospasm, cortical spreading ischemia, microcirculatory dysfunction, and microthrombosis are reported in both patients and animal models of SAH. We demonstrated previously that SAH is associated with increased oxidative stress in the brain parenchyma, and that this correlates with dysfunction of endothelial nitric oxide synthase (eNOS) (homodimeric uncoupling). Uncoupling of eNOS exacerbated oxidative stress and enhanced nitric oxide (NO) depletion, and was associated with multiple secondary complications such as microthrombosis, neuronal apoptosis, and release of reactive oxygen species. Thus, we hypothesized that genetic abbrogation of eNOS would confer a beneficial effect on the brain after SAH. Using a prechiasmatic injection model of SAH, we show here that eNOS knockout (KO) significantly alleviates vasospasm of the middle cerebral artery and reduces superoxide production. Endothelial nitric oxide synthase KO also affected other nitric oxide synthase isoforms. It significantly increases neuron nitric oxide synthase expression but has no effect on inducible nitric oxide synthase. Endothelial nitric oxide synthase KO decreases Zn(2+) release after SAH, reduces microthrombi formation, and prevent neuronal degeneration. This work is consistent with our findings where, after SAH, increased oxidative stress can uncouple eNOS via Zn(2+) thiolate oxidation, or theoretically by depletion or oxidation of tetrahydrobiopterin, resulting in a paradoxical release of superoxide anion radical, further exacerbating oxidative stress and microvascular damage.

Pharmacological inhibition of inducible nitric oxide synthase (iNOS) and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, convalesce behavior and biochemistry of hypertension induced vascular dementia in rats

Cognitive disorders are likely to increase over the coming years (5-10). Vascular dementia (VaD) has heterogeneous pathology and is a challenge for clinicians. Current Alzheimer's disease drugs have had limited clinical efficacy in treating VaD and none have been approved by major regulatory authorities specifically for this disease. Role of iNOS and NADPH-oxidase has been reported in various pathological conditions but there role in hypertension (Hypt) induced VaD is still unclear. This research work investigates the salutiferous effect of aminoguanidine (AG), an iNOS inhibitor and 4'-hydroxy-3'-methoxyacetophenone (HMAP), a NADPH oxidase inhibitor in Hypt induced VaD in rats. Deoxycorticosterone acetate-salt (DOCA-S) hypertension has been used for development of VaD in rats. Morris water-maze was used for testing learning and memory. Vascular system assessment was done by testing endothelial function. Mean arterial blood pressure (MABP), oxidative stress [aortic superoxide anion, serum and brain thiobarbituric acid reactive species (TBARS) and brain glutathione (GSH)], nitric oxide levels (serum nitrite/nitrate) and cholinergic activity (brain acetyl cholinesterase activity-AChE) were also measured. DOCA-S treated rats have shown increased MABP with impairment of endothelial function, learning and memory, reduction in serum nitrite/nitrate & brain GSH levels along with increase in serum & brain TBARS, and brain AChE activity. AG as well as HMAP significantly convalesce Hypt induced impairment of learning, memory, endothelial function, and alterations in various biochemical parameters. It may be concluded that AG, an iNOS inhibitor and HMAP, a NADPH-oxidase inhibitor may be considered as potential agents for the management of Hypt induced VaD.

Strategies and methods to study sex differences in cardiovascular structure and function: a guide for basic scientists

Background

Cardiovascular disease remains the primary cause of death worldwide. In the US, deaths due to cardiovascular disease for women exceed those of men. While cultural and psychosocial factors such as education, economic status, marital status and access to healthcare contribute to sex differences in adverse outcomes, physiological and molecular bases of differences between women and men that contribute to development of cardiovascular disease and response to therapy remain underexplored.

Methods

This article describes concepts, methods and procedures to assist in the design of animal and tissue/cell based studies of sex differences in cardiovascular structure, function and models of disease.

Results

To address knowledge gaps, study designs must incorporate appropriate experimental material including species/strain characteristics, sex and hormonal status. Determining whether a sex difference exists in a trait must take into account the reproductive status and history of the animal including those used for tissue (cell) harvest, such as the presence of gonadal steroids at the time of testing, during development or number of pregnancies. When selecting the type of experimental animal, additional consideration should be given to diet requirements (soy or plant based influencing consumption of phytoestrogen), lifespan, frequency of estrous cycle in females, and ability to investigate developmental or environmental components of disease modulation. Stress imposed by disruption of sleep/wake cycles, patterns of social interaction (or degree of social isolation), or handling may influence adrenal hormones that interact with pathways activated by the sex steroid hormones. Care must be given to selection of hormonal treatment and route of administration.

Conclusions

Accounting for sex in the design and interpretation of studies including pharmacological effects of drugs is essential to increase the foundation of basic knowledge upon which to build translational approaches to prevent, diagnose and treat cardiovascular diseases in humans.