Simvastatin Treatment Duration and Cognitive Preservation in Experimental Subarachnoid Hemorrhage

SIRT1 Activation Promotes Long-Term Functional Recovery After Subarachnoid Hemorrhage in Rats

BACKGROUND

An increase in sirtuin 1 (SIRT1) reportedly attenuates early brain injury, delayed cerebral ischemia, and short-term neurologic deficits in rodent models of subarachnoid hemorrhage (SAH). This study investigates the effect of resveratrol, a SIRT1 activator, on long-term functional recovery in a clinically relevant rat model of SAH.

METHODS

Thirty male Wistar rats were subjected to fresh arterial blood injection into the prechiasmatic space and randomized to receive 7 days of intraperitoneal resveratrol (20 mg/kg) or vehicle injections. Body weight and rotarod performance were measured on days 0, 3, 7, and 34 post SAH. The neurologic score was assessed 7 and 34 days post SAH. Morris water maze performance was evaluated 29-33 days post SAH. Brain SIRT1 activity and CA1 neuronal survival were also assessed.

RESULTS

Blood pressure rapidly increased in all SAH rats, and no between-group differences in blood pressure, blood gases, or glucose were detected. SAH induced weight loss during the first 7 days, which gradually recovered in both groups. Neurologic score and rotarod performance were significantly improved after resveratrol treatment at 34 days post SAH (p = 0.01 and 0.04, respectively). Latency to find the Morris water maze hidden platform was shortened (p = 0.02). In the resveratrol group, more CA1 neurons survived following SAH (p = 0.1). An increase in brain SIRT1 activity was confirmed in the resveratrol group (p < 0.05).

CONCLUSIONS

Treatment with resveratrol for 1 week significantly improved the neurologic score, rotarod performance, and latency to find the Morris water maze hidden platform 34 days post SAH. These findings indicate that SIRT1 activation warrants further investigation as a mechanistic target for SAH therapy.

Fluoxetine attenuates apoptosis in early brain injury after subarachnoid hemorrhage through Notch1/ASK1/p38 MAPK signaling pathway

Subarachnoid hemorrhage (SAH) is a severe brain condition associated with a significantly high incidence and mortality. As a consequence of SAH, early brain injury (EBI) may contribute to poor SAH patient outcomes. Apoptosis is a signaling pathway contributing to post-SAH early brain injury and the diagnosis of the disease. Fluoxetine is a well-studied serotonin selective reuptake inhibitor (SSRI). However, its role in apoptosis has not been clearly understood. The present investigation assessed the effects of Fluoxetine in apoptosis and the potential Notch1/ASK1/p38 MAPK signaling pathway in EBI after SAH. Adult C57BL/6 J mice were subjected to SAH. Study mice (56) were randomly divided into 4 groups: the surgery without SAH (sham (n = 8), SAH+ vehicle; (SAH+V) (n = 16), surgery+ Fluoxetine (Fluox), (n = 16) and SAH+ Fluoxetine (n = 16). Various parameters were investigated 12, 24, 48, and 72 h after induction of SAH. Western blot analysis, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL) staining, Immunohistochemistry (IHC), and flow cytometry were carried out in every experimental group. According to the findings, the SAH downregulated NOTCH1 signaling pathway, Jlk6 inhibited Notch1, Notch1 inactivation increased apoptotic protein expression and suppressed Bax, and cytochrome C. Fluoxetine reversed the effects of notch1 inhibition in SAH. The Neuroprotective Fluoxetine effects involved suppression of apoptosis post-SAH. In summary, early Fluoxetine treatment significantly attenuates apoptosis and the expression of apoptosis-related proteins after 72 h post-SAH. Fluoxetine may ameliorate early brain injury after subarachnoid hemorrhage through anti-apoptotic effects and Notch1/ASK1/p38 MAPK signaling pathway.

Statins Improve Clinical Outcome After Non-aneurysmal Subarachnoid Hemorrhage: A Translational Insight From a Systematic Review of Experimental Studies

The efficacy of statin-treatment in aneurysmal subarachnoid hemorrhage (SAH) remains controversial. We aimed to investigate the effects of statin-treatment in non-aneurysmal (na)SAH in accordance with animal research data illustrating the pathophysiology of naSAH. We systematically searched PubMed using PRISMA-guidelines and selected experimental studies assessing the statin-effect on SAH. Detecting the accordance of the applied experimental models with the pathophysiology of naSAH, we analyzed our institutional database of naSAH patients between 1999 and 2018, regarding the effect of statin treatment in these patients and creating a translational concept. Patient characteristics such as statin-treatment (simvastatin 40 mg/d), the occurrence of cerebral vasospasm (CVS), delayed infarction (DI), delayed cerebral ischemia (DCI), and clinical outcome were recorded. In our systematic review of experimental studies, we found 13 studies among 18 titles using blood-injection-animal-models to assess the statin-effect in accordance with the pathophysiology of naSAH. All selected studies differ on study-setting concerning drug-administration, evaluation methods, and neurological tests. Patients from the Back to Bedside project, including 293 naSAH-patients and 51 patients with simvastatin-treatment, were recruited for this analysis. Patients under treatment were affected by a significantly lower risk of CVS (p < 0.01; OR 3.7), DI (p < 0.05; OR 2.6), and DCI (p < 0.05; OR 3). Furthermore, there was a significant association between simvastatin-treatment and favorable-outcome (p < 0.05; OR 3). However, dividing patients with statin-treatment in pre-SAH (n = 31) and post-SAH (n = 20) treatment groups, we only detected a tenuously significant higher chance for a favorable outcome (p < 0.05; OR 0.05) in the small group of 20 patients with statin post-SAH treatment. Using a multivariate-analysis, we detected female gender (55%; p < 0.001; OR 4.9), Hunt&Hess ≤III at admission (p < 0.002; OR 4), no anticoagulant-therapy (p < 0.0001; OR 0.16), and statin-treatment (p < 0.0001; OR 24.2) as the main factors improving the clinical outcome. In conclusion, we detected a significantly lower risk for CVS, DCI, and DI in naSAH patients under statin treatment. Additionally, a significant association between statin treatment and favorable outcome 6 months after naSAH onset could be confirmed. Nevertheless, unified animal experiments should be considered to create the basis for developing new therapeutic schemes.

Common Data Elements for Unruptured Intracranial Aneurysm and Subarachnoid Hemorrhage Clinical Research: Recommendations from the Working Group on Long-Term Therapies

OBJECTIVES

The goal for the long-term therapies (LTT) working group (WG) of the Unruptured Intracranial Aneurysm (UIA) and Subarachnoid Hemorrhage (SAH) common data elements (CDEs) was to develop a comprehensive set of CDEs, data definitions, case report forms, and guidelines for use in UIA and SAH LTT clinical research, as part of a new joint effort between the National Institute of Neurological Disorders and Stroke (NINDS) and the National Library of Medicine of the US National Institutes of Health. These UIA and SAH CDEs will join other neurological disease-specific CDEs already developed and available for use by research investigators.

METHODS

The eight LTT WG members comprised international UIA, and SAH experts reviewed existing NINDS CDEs and instruments, created new elements when needed, and provided recommendations for future LTT clinical research. The recommendations were compiled, internally reviewed by the all UIA and SAH WGs and steering committee members. The NINDS CDE team also reviewed the final version before posting the SAH Version 1.0 CDE recommendations on the NINDS CDE website.

RESULTS

The NINDS UIA and SAH LTT CDEs and supporting documents are publicly available on the NINDS CDE ( https://www.commondataelements.ninds.nih.gov/#page=Default ) and NIH Repository ( https://cde.nlm.nih.gov/home ) websites. The subcommittee members discussed and reviewed various parameters, outcomes, and endpoints in UIA and SAH LTT studies. The following meetings with WG members, the LTT WG's recommendations are incorporated into the disease/injury-related events, assessments and examinations, and treatment/intervention data domains.

CONCLUSIONS

Noting gaps in the literature regarding medication and rehabilitation parameters in UIA and SAH clinical studies, the current CDE recommendations aim to arouse interest to explore the impact of medication and rehabilitation treatments and therapies and encourage the convergence of LTT clinical study parameters to develop a harmonized standard.

Cognitive Sequelae of Unruptured and Ruptured Intracranial Aneurysms and their Treatment: Modalities for Neuropsychological Assessment

BACKGROUND

Cognitive sequelae frequently follow subarachnoid hemorrhage (SAH) and include deficits across multiple domains of executive function. This factor affects overall functional outcomes negatively, especially in younger patients. Several clinical correlates predict development and severity of cognitive dysfunction after SAH. Hypothetical mechanisms of cognitive dysfunction in the absence of radiographic lesion include cerebral hypoperfusion and blood breakdown products, resulting in perturbed interneuronal communication and network synchrony, excitotoxicity, and altered microRNA expression.

METHODS

The PubMed database was searched for articles discussing cognitive outcomes in patients with unruptured and ruptured intracranial aneurysmal disease, sequelae of treatment, and modalities for neuropsychologic testing.

RESULTS

Treatment of unruptured intracranial aneurysms, although capable of preventing SAH, comes with its own set of complications and may also affect cognitive function. Neuropsychological tests such as the Montreal Cognitive Assessment, Mini-Mental Status Examination, and others have proved useful in evaluating cognitive decline. Studies using functional neurologic imaging modalities have identified regions with altered activation patterns during various cognitive tasks. The sum of research efforts in this field has provided useful insights and an initial understanding of cognitive dysfunction after aneurysm treatment and SAH that should prove useful in guiding and rendering future investigations more fruitful.

CONCLUSIONS

Development of finer and more sensitive neuropsychological tests in evaluating the different domains of cognitive function after aneurysm treatment and SAH in general will be useful in accurately determining outcomes after ictus and comparing efficacy of different therapeutic strategies.

Neurobehavioral testing in subarachnoid hemorrhage: A review of methods and current findings in rodents

The most important aspect of a preclinical study seeking to develop a novel therapy for neurological diseases is whether the therapy produces any clinically relevant functional recovery. For this purpose, neurobehavioral tests are commonly used to evaluate the neuroprotective efficacy of treatments in a wide array of cerebrovascular diseases and neurotrauma. Their use, however, has been limited in experimental subarachnoid hemorrhage studies. After several randomized, double-blinded, controlled clinical trials repeatedly failed to produce a benefit in functional outcome despite some improvement in angiographic vasospasm, more rigorous methods of neurobehavioral testing became critical to provide a more comprehensive evaluation of the functional efficacy of proposed treatments. While several subarachnoid hemorrhage studies have incorporated an array of neurobehavioral assays, a standardized methodology has not been agreed upon. Here, we review neurobehavioral tests for rodents and their potential application to subarachnoid hemorrhage studies. Developing a standardized neurobehavioral testing regimen in rodent studies of subarachnoid hemorrhage would allow for better comparison of results between laboratories and a better prediction of what interventions would produce functional benefits in humans.

Minimal Long-Term Neurobehavioral Impairments after Endovascular Perforation Subarachnoid Hemorrhage in Mice

Cognitive deficits are among the most severe and pervasive consequences of aneurysmal subarachnoid hemorrhage (SAH). A critical step in developing therapies targeting such outcomes is the characterization of experimentally-tractable pre-clinical models that exhibit multi-domain neurobehavioral deficits similar to those afflicting humans. We therefore searched for neurobehavioral abnormalities following endovascular perforation induction of SAH in mice, a heavily-utilized model. We instituted a functional screen to manage variability in injury severity, then assessed acute functional deficits, as well as activity, anxiety-related behavior, learning and memory, socialization, and depressive-like behavior at sub-acute and chronic time points (up to 1 month post-injury). Animals in which SAH was induced exhibited reduced acute functional capacity and reduced general activity to 1 month post-injury. Tests of anxiety-related behavior including central area time in the elevated plus maze and thigmotaxis in the open field test revealed increased anxiety-like behavior at subacute and chronic time-points, respectively. Effect sizes for subacute and chronic neurobehavioral endpoints in other domains, however, were small. In combination with persistent variability, this led to non-significant effects of injury on all remaining neurobehavioral outcomes. These results suggest that, with the exception of anxiety-related behavior, alternate mouse models are required to effectively analyze cognitive outcomes after SAH.

Increased Frontal Lobe Activation After Aneurysmal Subarachnoid Hemorrhage

BACKGROUND AND PURPOSE

Neurocognitive deficits are common among survivors of aneurysmal subarachnoid hemorrhage, even among those with good outcomes and no structural lesions. This study aims to probe the neurophysiological underpinnings of cognitive dysfunction among patients with ruptured intracranial aneurysms using magnetoencephalography (MEG).

METHODS

Thirteen patients who had undergone uncomplicated coiling for aneurysmal subarachnoid hemorrhage and 13 matched controls were enrolled. Neuropsychological tests were done before magnetoencephalography scans. Magnetoencephalography data were acquired in a 151-channel, whole-head magnetoencephalography system for resting state and 2 cognitive tasks (go-no-go and set-shifting). Mean time from treatment to test was 18.8 months.

RESULTS

Cognitive tasks of inhibition (go-no-go) indicated greater activation in the right anterior cingulate and inferior frontal gyrus, and cognitive set-shifting tasks (mental flexibility) indicated greater activity in the bilateral anterior cingulate cortex and right medial frontal gyrus among aneurysmal subarachnoid hemorrhage patients, with significantly different timing of activation between groups. Resting-state, beta-band connectivity of the anterior cingulate correlated negatively with Montreal Cognitive Assessment scores (left: r=-0.56; P<0.01 and right: r=-0.55; P<0.01): higher connectivity of this region was linked to poorer cognitive test performance.

CONCLUSIONS

We have shown increased activation in areas of the anterior cingulate gyrus and frontobasal regions during the execution of more demanding tasks in good grade. The degree of activation in the anterior cingulate gyrus has a negative correlation with cognitive (Montreal Cognitive Assessment) scores. These subtle differences may be related to the common neurocognitive and behavioral complaints seen in this patient population.

pH-sensitive NMDA inhibitors improve outcome in a murine model of SAH

BACKGROUND

Despite intensive research, neurological morbidity from delayed cerebral ischemia remains common after aneurysmal subarachnoid hemorrhage (SAH). In the current study, we evaluate the neuroprotective effects of a pH-dependent GluN2B subunit-selective NMDA receptor antagonist in a murine model of SAH.

METHODS

Following induction of SAH, 12 ± 2 week old male C57-BL/6 mice received NP10075, a pH-dependent NMDA receptor antagonist, or vehicle. In a separate series of experiments, NP10075 and the non-pH sensitive NMDA antagonist, NP10191, were administered to normoglycemic and hyperglycemic mice. Both histological (right middle cerebral artery diameter, NeuN, and Fluoro-Jade B staining) and functional endpoints (rotarod latency and neuroseverity score) were evaluated to assess the therapeutic benefit of NP10075.

RESULTS

Administration of NP10075 was well tolerated and had minimal hemodynamic effects following SAH. Administration of the pH-sensitive NMDA antagonist NP10075, but not NP10191, was associated with a durable improvement in the functional performance of both normoglycemic and hyperglycemic animals. NP10075 was also associated with a reduction in vasospasm in the middle cerebral artery associated with hemorrhage. There was no significant difference between treatment with nimodipine + NP10075, as compared to NP10075 alone.

CONCLUSIONS

These data demonstrate that use of a pH-dependent NMDA antagonist has the potential to work selectively in areas of ischemia known to undergo acidic pH shifts, and thus may be associated with selective regional efficacy and fewer behavioral side effects than non-selective NMDA antagonists.

Effect of preoperative simvastatin treatment on transplantation of cryopreserved-warmed mouse ovarian tissue quality

After the ovarian tissue (OT) transplantation, the ischemia-reperfusion injury causes depletion and apoptosis of follicle. Recent reports stated that simvastatin reduces ischemic damage. Therefore, we used the mouse whole ovarian vitrification and autotransplantation models to investigate the effects of simvastatin. Five-week-old B6D2F1 mice were randomly divided into four groups. Three groups were given simvastatin orally (5 mg/kg) before ovariectomy, either 2 hours before (2H Tx) or once a day for 3 or 7 days. The control group was given saline 2 hours before ovariectomy. All ovaries were cryopreserved by vitrification, held in liquid nitrogen for 1 week before being warmed, and autotransplanted. The grafts were collected for analysis on 2, 7, or 21 days after transplantation. Ovarian follicle morphology and apoptosis were assessed by hematoxylin and eosin staining and terminal deoxynucleotidyl transferase dUTP nick end labeling assay. Vessel integrity in ovary was evaluated by immunohistochemistry using anti-CD31 antibody. Serum FSH level was measured to estimate the transplanted ovarian reserve. The proportion of morphologically normal (G1) follicles at 7 and 21 days and the percentage of CD31 (+) tissue at 21 days was significantly higher in the 2H Tx group than that in the control group. In addition, the 2H Tx group showed a significantly increased intact primordial follicle ratio at 2 and 21 days after OT transplantation. Administration of simvastatin 2 hours before ovariectomy could improve the quality after transplantation of cryopreserved mouse OT.

Endovascular perforation subarachnoid hemorrhage fails to cause Morris water maze deficits in the mouse

Cognitive dysfunction is the primary driver of poor long-term outcome in aneurysmal subarachnoid hemorrhage (SAH) survivors; modeling such deficits preclinically is thus key for mechanistic and translational investigation. Although rat SAH causes long-term deficits in learning and memory, it remains unknown whether similar deficits are seen in the mouse, a species particularly amenable to powerful, targeted genetic manipulation. We thus subjected mice to endovascular perforation SAH and assessed long-term cognitive outcome via the Morris water maze (MWM), the most commonly used metric for rodent neurocognition. No significant differences in MWM performance (by either of two protocols) were seen in SAH versus sham mice. Moreover, SAH caused negligible hippocampal CA1 injury. These results undercut the potential of commonly used methods (of SAH induction and assessment of long-term neurocognitive outcome) for use in targeted molecular studies of SAH-induced cognitive deficits in the mouse.

Memantine alleviates brain injury and neurobehavioral deficits after experimental subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) causes brain injury via glutamate excitotoxicity, which leads to an excessive Ca(2+) influx and this starts an apoptotic cascade. Memantine has been proven to reduce brain injury in several types of brain insults. This study investigated the neuro-protective potential of memantine after SAH and explored the underlying mechanisms. An endovascular perforation rat model of SAH was used and Sprague-Dawley rats were randomized into sham surgery, SAH + vehicle, and SAH + memantine groups. The effects of memantine on SAH were evaluated by assessing the neuro-behavioral functions, blood-brain barrier (BBB) permeability and neuronal cell preservation. The mechanisms of action of memantine, with its N-methyl-D-aspartate (NMDA) antagonistic characteristics on nitric oxide synthase (NOS) expression and peroxynitrite formation, were also investigated. The apoptotic cascade after SAH was suppressed by memantine. Neuronal NOS (nNOS) expression, peroxynitrite formation, and subsequent oxidative/nitrosative stress were also reduced. Memantine effectively preserved BBB integrity, rescued neuronal injury, and improved neurological outcome in experimental SAH. Memantine has neuro-protective potential in experimental SAH and may help combat SAH-induced brain damage in the future.

Hyperbaric oxygen for cerebral vasospasm and brain injury following subarachnoid hemorrhage

The impact of acute brain injury and delayed neurological deficits due to cerebral vasospasm (CVS) are major determinants of outcomes after subarachnoid hemorrhage (SAH). Although hyperbaric oxygen (HBO) had been used to treat patients with SAH, the supporting evidence and underlying mechanisms have not been systematically reviewed. In the present paper, the overview of studies of HBO for cerebral vasospasm is followed by a discussion of HBO molecular mechanisms involved in the protection against SAH-induced brain injury and even, as hypothesized, in attenuating vascular spasm alone. Faced with the paucity of information as to what degree HBO is capable of antagonizing vasospasm after SAH, the authors postulate that the major beneficial effects of HBO in SAH include a reduction of acute brain injury and combating brain damage caused by CVS. Consequently, authors reviewed the effects of HBO on SAH-induced hypoxic signaling and other mechanisms of neurovascular injury. Moreover, authors hypothesize that HBO administered after SAH may "precondition" the brain against the detrimental sequelae of vasospasm. In conclusion, the existing evidence speaks in favor of administering HBO in both acute and delayed phase after SAH; however, further studies are needed to understand the underlying mechanisms and to establish the optimal regimen of treatment.

Statins improve outcome in murine models of intracranial hemorrhage and traumatic brain injury: a translational approach

Traumatic brain injury (TBI) and intracerebral hemorrhage (ICH) are leading causes of neurological mortality and disability in the U.S. However, therapeutic options are limited and clinical management remains largely supportive. HMG-CoA reductase inhibitors (statins) have pleiotropic mechanisms of action in the setting of acute brain injury, and have been demonstrated to improve outcomes in preclinical models of ICH and TBI. To facilitate translation to clinical practice, we now characterize the optimal statin and dosing paradigm in murine models of ICH and TBI. In a preclinical model of TBI, mice received vehicle, simvastatin, and rosuvastatin at doses of 1 mg/kg and 5 mg/kg for 5 days after the impact. Immunohistochemistry, differential gene expression, and functional outcomes (rotarod and Morris water maze testing) were assessed to gauge treatment response. Following TBI, administration of rosuvastatin 1 mg/kg was associated with the greatest improvement in functional outcomes. Rosuvastatin treatment was associated with histological evidence of reduced neuronal degeneration at 24 h post-TBI, reduced microgliosis at day 7 post-TBI, and preserved neuronal density in the CA3 region at 35 days post-injury. Administration of rosuvastatin following TBI was also associated with downregulation of inflammatory gene expression in the brain. Following ICH, treatment with simvastatin 1 mg/kg was associated with the greatest improvement in functional outcomes, an effect that was independent of hemorrhage volume. Clinically relevant models of acute brain injury may be used to define variables such as optimal statin and dosing paradigms to facilitate the rational design of pilot clinical trials.

A novel intravital method to evaluate cerebral vasospasm in rat models of subarachnoid hemorrhage: a study with synchrotron radiation angiography

Precise in vivo evaluation of cerebral vasospasm caused by subarachnoid hemorrhage has remained a critical but unsolved issue in experimental small animal models. In this study, we used synchrotron radiation angiography to study the vasospasm of anterior circulation arteries in two subarachnoid hemorrhage models in rats. Synchrotron radiation angiography, laser Doppler flowmetry-cerebral blood flow measurement, [¹²⁵I]N-isopropyl-p-iodoamphetamine cerebral blood flow measurement and terminal examinations were applied to evaluate the changes of anterior circulation arteries in two subarachnoid hemorrhage models made by blood injection into cisterna magna and prechiasmatic cistern. Using synchrotron radiation angiography technique, we detected cerebral vasospasm in subarachnoid hemorrhage rats compared to the controls (p<0.05). We also identified two interesting findings: 1) both middle cerebral artery and anterior cerebral artery shrunk the most at day 3 after subarachnoid hemorrhage; 2) the diameter of anterior cerebral artery in the prechiasmatic cistern injection group was smaller than that in the cisterna magna injection group (p<0.05), but not for middle cerebral artery. We concluded that synchrotron radiation angiography provided a novel technique, which could directly evaluate cerebral vasospasm in small animal experimental subarachnoid hemorrhage models. The courses of vasospasm in these two injection models are similar; however, the model produced by prechiasmatic cistern injection is more suitable for study of anterior circulation vasospasm.

Statins in the management of aneurysmal subarachnoid hemorrhage: an overview of animal research, observational studies, randomized controlled trials and meta-analyses

BACKGROUND

the pathophysiology of delayed neurological deficits (DNDs) following aneurysmal subarachnoid hemorrhage (SAH) is complex, and is not limited to arterial narrowing (vasospasm) and classical ischemia. Thus, combined drug approaches, or therapies with multiple effects, may have the greatest potential for benefit. Statins are known to have pleiotropic vascular effects, some of which may interrupt the pathogenesis of DNDs. Based on promising preliminary reports, many clinicians routinely administer statins to prevent DNDs.

METHODS

a systematic review was performed to identify and summarize all animal research, observational studies, randomized controlled trials (RCTs) and meta-analyses which have evaluated the use of statins in the management of SAH.

RESULTS

nine animal studies, nine observational (cohort and case-control) studies, six RCTs and three meta-analyses were identified. Animal studies have generally administered statin doses that, when adjusted for body weight, are 10-80 times larger than what is used in humans. Nevertheless, these models have consistently reported statins to reduce vasospasm and to demonstrate additional neuroprotective effects. However, observational studies have not revealed an association between statin-use and reduced DNDs or improved neurological outcomes. Results of RCTs have been inconsistent and limited by small sample size, but together suggest that statins may reduce DNDs, with no clear impact on mortality or neurological recovery. Optimal drug administration strategies (timing of initiation, most effective dose and duration) have not been clarified.

CONCLUSIONS

the role of statins in the management of patients with SAH remains unclear. Although promising, statins should not, at this time, be considered standard care.

Simvastatin re-couples dysfunctional endothelial nitric oxide synthase in experimental subarachnoid hemorrhage

Reduced endothelial nitric oxide synthase (eNOS) function has been linked to secondary complications of subarachnoid hemorrhage (SAH). We previously found that there is increased eNOS function after SAH but that it is uncoupled, leading to secondary complications such as vasospasm, microthromboembolism and neuronal apoptosis. Here we test the hypothesis that recoupling eNOS with simvastatin can prevent these complications. SAH was created in mice that were treated with vehicle or simvastatin starting 2 weeks before or 30 minutes after SAH. SAH increased phosphorylated eNOS which was prevented by pre- or post-treatment with simvastatin. Simvastatin pre-treatment also prevented the increase in eNOS monomer formation that was associated with SAH, decreased superoxide anion radical production and increased NO. These changes were associated with decreased vasospasm, microthromboemboli and neuronal injury. The data suggest that simvastatin re-couples eNOS after SAH, leading to decreased secondary complications such as vasospasm, microthromboemboli and neuronal injury.