A new grading system evaluating bleeding scale in filament perforation subarachnoid hemorrhage rat model

Effect of recombinant osteopontin on cerebral vasospasm after subarachnoid hemorrhage in rats

BACKGROUND

osteopontin (OPN), a pleiotropic extracellular matrix glycoprotein, has been reported to have neuroprotective effects against early brain injury after subarachnoid hemorrhage (SAH). The aim of this study is to examine if osteopontin prevents cerebral vasospasm after SAH in rats.

METHOD

the endovascular perforation model of SAH was produced, and 62 rats were randomly assigned to sham + vehicle, SAH + vehicle, and SAH+ r-OPN (0.1 microg) groups. Cerebral vasospasm was evaluated by India ink angiography at 24 and 72 h after SAH, as well as neurobehavioral tests.

FINDINGS

significant vasospasm and neurological impairments occurred over the observed period after SAH. r-OPN significantly prevented vasospasm in the left middle cerebral artery at 24 h and improved neurological impairments at 48 h after SAH. In other time points studied, r-OPN had a tendency toward improving both vasospasm and neurological scores, but the difference was not significant.

CONCLUSIONS

this study shows that r-OPN has anti-vasospastic effects against cerebral vasospasm after SAH.

Tyrosine phosphatase inhibition attenuates early brain injury after subarachnoid hemorrhage in rats

PURPOSE

Sodium orthovanadate (SOV) is a representative tyrosine phosphatase inhibitor and has been shown to ameliorate neuronal injury in cerebral ischemia. We hypothesized that tyrosine phosphatase inhibition by SOV might attenuate early brain injury after subarachnoid hemorrhage (SAH) in this study.

METHODS

The endovascular perforation model of SAH was produced and animals were randomly assigned to sham-operated rats, saline-treated (vehicle), and 10 mg/kg of SOV-treated SAH rats. Drugs were injected intraperitoneally immediately after SAH induction. Neurological score and brain water content (BWC) were assessed at 24 h after SAH. Cell injury was studied by terminal deoxynucleotidyl transferase-mediated uridine 5'-triphosphate-biotin nick end-labeling (TUNEL) at 24 h after SAH.

RESULTS

Severity of SAH and mortality in SOV-treated rats was similar to that of the saline group. SOV significantly decreased BWC and improved neurological score at 24 h after SAH compared with the saline group. SOV decreased TUNEL-positive cells at 24 h after SAH compared with the saline group.

CONCLUSIONS

These data suggest that tyrosine phosphatase inhibition by SOV ameliorates early brain injury after SAH.

Role of osteopontin in early brain injury after subarachnoid hemorrhage in rats

BACKGROUND

Subarachnoid hemorrhage (SAH)-induced early brain injury (EBI) contributes to delayed ischemic neurological deficits, one of whose key pathologic manifestation is the blood-brain barrier (BBB) disruption. Although post-SAH BBB breakdown is a self-repairable phenomenon, the molecular pathways are unknown. We determined the role of osteopontin (OPN), a pleiotropic extracellular matrix glycoprotein, in the post-SAH BBB disruption in rats.

METHOD

First, we produced the endovascular perforation model of SAH and studied if OPN is induced in the brain after SAH. Secondly, we examined the effects of blockage of endogenous OPN induction on neurological impairments and BBB disruption. Thirdly, we evaluated the effects of exogenous OPN on neurological impairments, brain edema and BBB disruption, and the related protein expression levels.

FINDINGS

OPN was significantly induced and peaked at 72 h after SAH, in the recovery phase of EBI. OPN small interfering RNA significantly aggravated neurological impairment and BBB disruption 72 h after SAH. Exogenous OPN significantly prevented neurological impairment, brain edema and BBB disruption associated with the deactivation of nuclear factor-κB activity, the inhibition of matrix metalloproteinase (MMP)-9 induction and tissue inhibitor of MMP-1 reduction, and the consequent preservation of cerebral microvessel basal lamina protein laminin and tight junction protein zona occludens-1.

CONCLUSIONS

These findings suggest the protective effects of OPN against BBB disruption after SAH, a finding which should provide a novel therapeutic approach for post-SAH EBI.

Vascular Dysfunction in Brain Hemorrhage: Translational Pathways to Developing New Treatments from Old Targets

Hemorrhagic stroke which is a form of stroke that affects 20% of all stroke patients is a devastating condition for which new treatments must be developed. Current treatment methods are quite insufficient to reduce long term morbidity and high mortality rate, up to 50%, associated with bleeding into critical brain structures, into ventricular spaces and within the subarachnoid space. During the last 10-15 years, significant advances in the understanding of important mechanisms that contribute to cell death and clinical deficits have been made. The most important observations revolve around a key set of basic mechanisms that are altered in brain bleeding models, including activation of membrane metalloproteinases, oxidative stress and both inflammatory and coagulation pathways. Moreover, it is now becoming apparent that brain hemorrhage can activate the ischemic stroke cascade in neurons, glial cells and the vascular compartment. The activation of multiple pathways allows comes the opportunity to intervene pharmacologically using monotherapy or combination therapy. Ultimately, combination therapy or pleiotropic compounds with multi-target activities should prove to be more efficacious than any single therapy alone. This article provides a comprehensive look at possible targets for small molecule intervention as well as some new approaches that result in metabolic down-regulation or inhibition of multiple pathways simultaneously.

Recombinant osteopontin in cerebral vasospasm after subarachnoid hemorrhage

OBJECTIVE

Osteopontin (OPN), a pleiotropic extracellular matrix glycoprotein, has been reported to be protective against ischemic lesions, but effects of OPN on vascular functions have not been investigated. The aim of this study was to assess whether recombinant OPN (r-OPN) could prevent cerebral vasospasm after subarachnoid hemorrhage (SAH) in rats.

METHODS

r-OPN was administered intraventricularly to rats undergoing SAH by endovascular perforation, and its protective effects were evaluated by measuring the diameter of cerebral arteries and neurobehavioral testing. Western blotting and immunofluorescence were performed to explore the underlying mechanisms. An integrin receptor antagonist GRGDSP or mitogen-activated protein kinase (MAPK) phosphatase (MKP)-1 small interfering RNA (siRNA) was also administered to r-OPN-treated SAH rats, and those effects were evaluated.

RESULTS

Pre-SAH administration of r-OPN prevented vasospasm and neurological impairments at 24-72 hours post-SAH. r-OPN enhanced an endogenous MAPK inhibitor, MKP-1, and suppressed the phosphorylation of MAPKs, caldesmon, and heat shock protein 27 in the spastic cerebral arteries at 24 hours post-SAH. Immunofluorescence revealed that MKP-1 was induced in the arterial smooth muscle layer. GRGDSP prevented r-OPN-induced MKP-1 upregulation, and MKP-1 siRNA abolished both MAPK inactivation and anti-vasospastic effects by r-OPN. Post-SAH r-OPN treatment also prevented vasospasm.

INTERPRETATION

r-OPN induced MKP-1 in the spastic cerebral arteries via binding to L-arginyl-glycyl-L-aspartate-dependent integrin receptors and prevented vasospasm after SAH. Therapeutic induction of MKP-1 may be a novel approach for the prevention and treatment of cerebral vasospasm.

Hemoglobin and iron handling in brain after subarachnoid hemorrhage and the effect of deferoxamine on early brain injury

The purpose of this study was to investigate hemoglobin and iron handling after subarachnoid hemorrhage (SAH), examine the relationship between iron and neuroglial cell changes, and determine whether deferoxamine (DFX) can reduce SAH-induced injury. The SAH was induced in Sprague-Dawley rats (n=110) using an endovascular perforation technique. Animals were treated with DFX (100 mg/kg) or vehicle 2 and 6 hours after SAH induction followed by every 12 hours for 3 days. Rats were killed at 6 hours, Days 1 and 3 to determine nonheme iron and examine iron-handling proteins using Western blot and immunohistochemistry. 8-Hydroxyl-2'-deoxyguanosine and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) staining were performed to assess oxidative DNA damage and neuronal cell death. After SAH, marked heme-oxygenase-1 (HO-1) upregulation at Day 3 (P<0.01) was accompanied by elevated nonheme iron (P<0.01), transferrin (Tf) (P<0.01), Tf receptor (P<0.05), and ferritin levels (P<0.01). Deferoxamine treatment reduced SAH-induced mortality (12% versus 29%, P<0.05), brain nonheme iron concentration, iron-handling protein expression, oxidative stress, and neuronal cell death at Day 3 (P<0.01) after SAH. These results suggest that iron overload in the acute phase of SAH causes oxidative injury leading to neuronal cell death. Deferoxamine effectively reduced oxidative stress and neuronal cell death, and may be a potential therapeutic agent for SAH.

Ferrous chelator 2,2'-dipyridyl attenuates cerebral vasospasm after experimental subarachnoid haemorrhage in rabbits

The effect of 2,2'-dipyridyl (DP) on cerebral vasospasm was investigated in a double-injection rabbit model of subarachnoid haemorrhage (SAH). Thirty-six animals were divided between four groups: control (sham-operated), SAH (model alone), SAH + DP (the SAH model in which DP dissolved in dimethyl sulphoxide [DMSO] was injected once daily for 5 days into the cisterna magna), and SAH + DMSO (the SAH model in which DMSO [vehicle] was injected daily for 5 days). There were significant differences in the basilar artery luminal area, wall thickness, neurological deficit score and vasospasm index between the SAH + DP and SAH groups. There was a significant negative correlation between arterial luminal area and arterial wall thickness, and also between the neurological deficit score and vasospasm index. Cells that were positive for terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labelling (TUNEL) and p53 expression were significantly increased in the SAH + DMSO and SAH groups, but not in the SAH + DP group, versus controls. Thus, DP may attenuate cerebral vasospasm after SAH by suppressing p53-induced apoptosis in the cerebral vessels.

Mechanisms of osteopontin-induced stabilization of blood-brain barrier disruption after subarachnoid hemorrhage in rats

BACKGROUND AND PURPOSE

Osteopontin (OPN) is an inducible, multifunctional, extracellular matrix protein that may be protective against blood-brain barrier (BBB) disruption after subarachnoid hemorrhage (SAH). However, the protective mechanisms remain unclear.

METHODS

We produced the endovascular perforation model of SAH in rats and studied the time course of OPN induction in brains by Western blotting and immunofluorescence (n=50). Then, 34 rats were randomly assigned to sham (n=3), sham+OPN small interfering RNA (siRNA, n=3), SAH+negative control siRNA (n=14), and SAH+OPN siRNA (n=14) groups, and 109 rats were allocated to sham+vehicle (n=17), sham+recombinant OPN (n=17), SAH+vehicle (n=33), SAH+recombinant OPN (n=31), and SAH+recombinant OPN+L-arginyl-glycyl-L-aspartate motif-containing hexapeptide (n=11) groups. The effects of OPN siRNA or recombinant OPN on BBB disruption and related proteins were studied.

RESULTS

OPN was significantly induced in reactive astrocytes and capillary endothelial cells, peaking at 72 hours after SAH, during the recovery phase of BBB disruption. Blockage of endogenous OPN induction exacerbated BBB disruption and was associated with a reduction of angiopoietin-1 and mitogen-activated protein kinase (MAPK) phosphatase-1 (an endogenous MAPK inhibitor), activation of MAPKs, and induction of vascular endothelial growth factor-A at 72 hours after SAH, whereas recombinant OPN treatment improved it and was associated with MAPK phosphatase-1 induction, MAPK inactivation, and vascular endothelial growth factor-A reduction, which was blocked by L-arginyl-glycyl-L-aspartate motif-containing hexapeptide at 24 hours after SAH. Vascular endothelial growth factor-B and angiopoietin-2 levels were unchanged.

CONCLUSIONS

OPN may increase MAPK phosphatase-1 that inactivates MAPKs, upstream and downstream of vascular endothelial growth factor-A, by binding to L-arginyl-glycyl-L-aspartate-dependent integrin receptors, suggesting a novel mechanism of OPN-induced post-SAH BBB protection.

Protective effects of recombinant osteopontin on early brain injury after subarachnoid hemorrhage in rats

OBJECTIVE

Accumulated evidence suggests that the primary cause of poor outcome after subarachnoid hemorrhage is not only cerebral arterial narrowing but also early brain injury. Our objective was to determine the effect of recombinant osteopontin, a pleiotropic extracellular matrix glycoprotein, on early brain injury after subarachnoid hemorrhage in rats.

DESIGN

Controlled in vivo laboratory study.

SETTING

Animal research laboratory.

SUBJECTS

One hundred seventy-seven male adult Sprague-Dawley rats weighing 300 to 370 g.

INTERVENTIONS

The endovascular perforation model of subarachnoid hemorrhage was produced. Subarachnoid hemorrhage or sham-operated rats were treated with an equal volume (1 microL) of pre-subarachnoid hemorrhage intracerebroventricular administration of two dosages (0.02 and 0.1 microg) of recombinant osteopontin, albumin, or vehicle. Body weight, neurologic scores, brain edema, and blood-brain barrier disruption were evaluated, and Western blot analyses were performed to determine the effect of recombinant osteopontin on matrix metalloproteinase-9, substrates of matrix metalloproteinase-9 (zona occludens-1, laminin), tissue inhibitor of matrix metalloproteinase-1, inflammation (interleukin-1beta), and nuclear factor-kappaB signaling pathways.

MEASUREMENTS AND MAIN RESULTS

Treatment with recombinant osteopontin prevented a significant loss in body weight, neurologic impairment, brain edema, and blood-brain barrier disruption after subarachnoid hemorrhage. These effects were associated with the deactivation of nuclear factor-kappaB activity, inhibition of matrix metalloproteinase-9 induction, the maintenance of tissue inhibitor of matrix metalloproteinase-1, the consequent preservation of the cerebral microvessel basal lamina protein laminin, and the tight junction protein zona occludens-1.

CONCLUSIONS

These results demonstrate that recombinant osteopontin treatment is effective for early brain injury after subarachnoid hemorrhage.

Role of gap junctions in early brain injury following subarachnoid hemorrhage

Gap junction inhibition has been demonstrated to reverse the vascular contraction that follows experimental subarachnoid hemorrhage. This study hypothesizes that the use of established gap junction inhibitors: octonal and carbenoxolone, to interrupt cell to cell communication will provide neuroprotection against early brain injury after SAH. The filament perforation model of SAH was performed in male Sprague-Dawley rats weighing between 300 and 380 g. Octanol (260.46 mg or 781.38 mg/kg), carbenoxolone (100 mg/kg), or vehicles were given via intraperitoneal injection 1 h after SAH. Neurologic deficits and cerebral apoptosis were assessed 24 and 72 h after SAH. In addition, Western blot analysis was performed to confirm the in vivo inhibition of CNS gap junctions. The administration of octanol and carbenoxolone both failed to attenuate the neurological deficits induced by SAH, and they did not reduce neuronal apoptosis. Additionally, carbenoloxone increased post SAH mortality and exacerbated SAH-induced apoptosis. Despite previous studies that show gap junction inhibitors reverse vasospasm following experimental SAH, they failed to improve clinical outcomes or provide neuroprotection in this study.

Long-term benefits after treatment of traumatic brain injury with simvastatin in rats

OBJECTIVE

This study was designed to investigate the long-term effects of simvastatin treatment after traumatic brain injury (TBI) in rats.

METHODS

Adult female Wistar rats (n = 24) were injured with controlled cortical impact and divided into 3 groups. The first 2 groups were treated with simvastatin (0.5 or 1.0 mg/kg) administered orally for 14 days starting 1 day after TBI. The third group (control) received phosphate-buffered saline orally for 14 days. Neurological functional outcome was measured with modified neurological severity scores performed 1 day before TBI; on days 1, 4, 7, 14 after TBI; and biweekly thereafter. All animals were sacrificed 3 months after TBI. Brain tissues of half of the animals were processed for preparation of paraffin-embedded sections for immunohistological studies. The remaining half were frozen for enzyme-linked immunosorbent assay studies for quantification of brain-derived neurotrophic factor (BDNF) in the hippocampus and cortex.

RESULTS

The results showed that both doses of simvastatin significantly improved functional outcome compared with the control, with no difference between the 2 doses. Simvastatin treatment of 1.0 mg/kg increased the number of morphologically intact neurons in the hippocampus, but treatment of 0.5 mg/kg had no significant effect. Enzyme-linked immunosorbent assay studies showed that 0.5 mg/kg simvastatin significantly increased BDNF levels within the hippocampus, but 1.0 mg/kg had no significant effect. Neither dose had any effect on BDNF levels within the cortex.

CONCLUSION

Simvastatin treatment provides long-lasting functional improvement after TBI in rats. It also enhances neuronal survival in the hippocampus and increases BDNF levels in the hippocampus secondary to simvastatin treatment.

Neurological and neurobehavioral assessment of experimental subarachnoid hemorrhage

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

Role of interleukin-1beta in early brain injury after subarachnoid hemorrhage in mice

BACKGROUND AND PURPOSE

The role of interleukin (IL)-1beta remains unknown in early brain injury (EBI) after subarachnoid hemorrhage (SAH), although IL-1beta has been repeatedly reported to increase in the brain and cerebrospinal fluid. The aim of this study is to examine the effects of IL-1beta inactivation on EBI after SAH in mice.

METHODS

The endovascular perforation model of SAH was produced and 112 mice were assigned to sham, SAH+ vehicle, and SAH+ N-Ac-Tyr-Val-Ala-Asp-chloromethyl ketone (Ac-YVAD-CMK, 6 and 10 mg/kg) groups. Ac-YVAD-CMK, a selective inhibitor of IL-1beta converting enzyme, or vehicle was administered intraperitoneally 1 hour post-SAH. EBI was assessed in terms of mortality within 24 hours, neurological scores, brain water content at 24 and 72 hours, Evans blue dye extravasation and Western blot for IL-1beta, c-Jun N-Terminal kinase (JNK), matrix metalloproteinase (MMP)-9, and zonula occludens (ZO)-1 at 24 hours after SAH.

RESULTS

High-dose (10 mg/kg) but not low-dose (6 mg/kg) treatment group significantly improved neurological scores, mortality, brain water content, and Evans blue dye extravasation compared with the vehicle group. Although both dosages of Ac-YVAD-CMK attenuated the mature IL-1beta induction, only high-dose treatment group significantly inhibited the phosphorylation of JNK, MMP-9 induction, and ZO-1 degradation.

CONCLUSIONS

IL-1beta activation may play an important role in the pathogenesis of EBI after SAH. The neurovascular protection of Ac-YVAD-CMK may be provided by the inhibition of JNK-mediated MMP-9 induction and the consequent preservation of tight junction protein ZO-1.

Thrombin inhibition by argatroban ameliorates early brain injury and improves neurological outcomes after experimental subarachnoid hemorrhage in rats

BACKGROUND AND PURPOSE

We investigated the role of thrombin in early brain injury after subarachnoid hemorrhage (SAH).

METHODS

The standard intravascular perforation model was used to produce experimental SAH in Sprague Dawley rats. Low-dose (0.3 mg/h) and high-dose (0.9 mg/h) argatroban, a direct thrombin inhibitor, were evaluated for effects on brain edema, blood-brain barrier (BBB) disruption, apoptotic cell death, inflammatory marker, and neurological outcomes after SAH.

RESULTS

Both doses of argatroban attenuated BBB disruption; however, only high-dose was effective in lowering edema in all brain regions, reducing cell death, and inflammatory marker expression, and improving neurological outcomes.

CONCLUSIONS

Thrombin inhibition by argatroban improves neurological outcomes and provides neuroprotection against acute events after SAH such as BBB disruption, brain edema, and cell death.

Simvastatin attenuation of cerebral vasospasm after subarachnoid hemorrhage in rats via increased phosphorylation of Akt and endothelial nitric oxide synthase

The mechanisms involved in simvastatin-mediated attenuation of cerebral vasospasm after subarachnoid hemorrhage (SAH) are unclear. We investigated the role of the phosphatidylinositol 3-kinase/Akt (PI3K/Akt) pathway and endothelial nitric oxide synthase (eNOS) in the cerebral vasculature in statin-mediated attenuation of cerebral vasospasm using wortmannin, an irreversible pharmacological PI3K inhibitor, and a rat SAH endovascular perforation model. Simvastatin was administered intraperitoneally in two dosages (1 mg/kg and 20 mg/kg) at 0.5, 24, and 48 hr after SAH and histological parameters of ipsilateral intracranial carotid artery (ICA) were assessed at 24 and 72 hr. SAH significantly decreased ICA diameter and perimeter while increasing wall thickness at both 24 and 72 hr. High-dosage simvastatin prevented the reduction of ICA diameter and perimeter following SAH, whereas both high and low dosages reduced wall thickness significantly at 24 and 72 hr. The effects of simvastatin were significantly reversed by wortmannin. High-dosage simvastatin increased pAkt and peNOS (phosphorylated forms) levels without increasing Akt and eNOS expression compared with the SAH group and also improved neurological deficits at 24 and 72 hr. Simvastatin did not affect protein levels by itself compared with untreated sham group. The present study elucidates the critical role of the PI3K activation leading to phosphorylation of Akt and eNOS in simvastatin-mediated attenuation of cerebral vasospasm after SAH.

Atorvastatin ameliorates cerebral vasospasm and early brain injury after subarachnoid hemorrhage and inhibits caspase-dependent apoptosis pathway

Backgroud

Cerebral vasospasm (CVS) and early brain injury remain major causes of morbidity and mortality after aneurysmal subarachnoid hemorrhage (SAH). Hydroxymethylglutaryl coenzyme A reductase inhibitors, also known as statins, has the neuroprotective effects and ameliorating CVS after SAH. This study was designed to explore apoptosis inhibiting effects of atorvastatin and its potential apoptotic signal pathway after SAH.

Results

Preserving blood-brain-barrier permeability, decreasing brain edema, increasing neurological scores and ameliorating cerebral vasospasm were obtained after prophylactic use of atorvastatin. TUNEL-positive cells were reduced markedly both in basilar artery and in brain cortex by atorvastatin. Apoptosis-related proteins P53, AIF and Cytochrome C were up-regulated after SAH, while they were not affected by atorvastatin. In addition, up-regulation of caspase-3 and caspase-8 after SAH was decreased by atorvastatin treatment both in mRNA and in protein levels.

Conclusion

The neuroprotective effects of atorvastatin after SAH may be related to its inhibition of caspase-dependent proapoptotic pathway based on the present results.

Long-term assessment of motor and cognitive behaviours in the intraluminal perforation model of subarachnoid hemorrhage in rats

The endovascular perforation model of subarachnoid hemorrhage (SAH) is a commonly used model in rats as it is performed without a craniotomy and accurately mimics the physiological effects of SAH in humans. The long-term behavioural profile of the model, however, has not been characterized. Given that humans often have cognitive deficits following SAH, we set out to characterize the behavioural profile as well as the spontaneous temperature changes of rats following intraluminal perforation. Rats were pre-trained on three motor tasks (tapered beam, limb-use asymmetry and the horizontal ladder tasks) prior to receiving a SAH. The animals were then assessed on post-surgical days 3, 7, 14 and 21 on these tasks. At the completion of motor testing, the rats were assessed on a moving platform version of the Morris water task. Despite significant mortality (33%), SAH did not result in lasting motor deficits on any of the tasks examined. However, the SAH group did show a minor cognitive impairment in the Morris water task. In addition, SAH produced a slight, but significant elevation in body temperature (vs. sham operated rats) despite an acute decrease in general home cage activity. The majority of the animals did not have any observable infarcts and the SAH did not significantly affect cortical thickness. In summary, the endovascular perforation model of SAH results in no lasting motor deficits and only minor cognitive impairment in survivors, which alone would be difficult to evaluate in neuroprotection or rehabilitation studies.

Effects of melatonin in early brain injury following subarachnoid hemorrhage

BACKGROUND

Aneurysmal subarachnoid hemorrhage (SAH) is a devastating disease that is associated with significant morbidity and mortality. There is substantial evidence to suggest that oxidative stress is significant in the development of acute brain injury following SAH. Melatonin is a strong antioxidant that has low toxicity and easily passes through the BBB. Previous studies have shown that melatonin provides neuroprotection in other models of CNS injury.

METHODS

This experiment evaluates melatonin as a neuroprotectant against early brain injury following SAH. The endovascular perforation model of SAH was performed in male Sprague Dawley rats followed by the administration of melatonin two hours after the insult. Mortality and brain water content were assessed 24 after SAH.

FINDINGS

A significant reduction in 24 h mortality was seen following treatment with 150 mg/kg of melatonin. Brain water content was evaluated in the high dose treatment group to see if a reduction in brain edema was associated with reduced mortality. High dose melatonin tended to reduce brain water content following SAH.

CONCLUSIONS

Large doses of melatonin significantly reduced mortality and brain water content in rats following SAH.