Animal Models Of Cerebral Ischemia Research Articles

Abstract WP119: Effects of Indirect Revascularization with Synangiosis in New Vessel Formation in an Animal Model of Cerebral Ischemia.

Objective: In order to study the mechanisms associated with neovascularization after indirect bypass (EDAS), we have developed a mice model of synangiosis and cerebral ischemia. Method: Healthy 12-24 week old male C57/BL6J mice were used. The temporalis muscle served as donor for the external carotid artery vessels through a window in the temporalis bone. The distal MCA was ligated after opening the dura. The temporalis muscle was reattached in direct apposition to the ischemic brain surface. Animals were sacrificed at one month and their heads were prepared in block. Brain slices were stained with CD31 (endothelial cell marker), Ki67 (proliferation maker), and DAPI (nuclear marker) antibodies. Confocal laser microscopy was used for immunofluorescent imaging. Standardized relative quantification of immunofluorescence staining was performed using ImageJ following the Arqués protocol. Inferential comparisons among groups were performed with a generalized linear model. Data was nested in the model by animal to account for intrasubject correlation. Results: A total of 12 mice were operated. One subject died after surgery (attrition rate 8%). All other subjects displayed no deficits. The number of DAPI+ cells/image was no different between the synangiosis and the control side. The index CD31/DAPI was significantly higher in the synangiosis side (mean 0.90 ± 1.13 vs. controls: 0.60 ± 0.65, p<0.001). The proliferation index Ki67/DAPI was significantly higher in the synangiosis side (mean 0.21 ± 0.08 vs. controls: 0.12 ± 0.05, p=0.03). There was 8% colocalization of the 3 markers on the synangiosis side and none on the controls. Conclusions: Our model of synangiosis in mice was well tolerated and produced quantifiable neovascularization in the brain as indicated by the neovascularization indexes observed in confocal microscopy. This model of synangiosis is a promising tool for future studies of neovascularization and collateral formation in individuals with ischemia.

Molecular Mechanisms Responsible for Neuron-Derived Conditioned Medium (NCM)-Mediated Protection of Ischemic Brain.

The protective value of neuron-derived conditioned medium (NCM) in cerebral ischemia and the underlying mechanism(s) responsible for NCM-mediated brain protection against cerebral ischemia were investigated in the study. NCM was first collected from the neuronal culture growing under the in vitro ischemic condition (glucose-, oxygen- and serum-deprivation or GOSD) for 2, 4 or 6 h. Through the focal cerebral ischemia (bilateral CCAO/unilateral MCAO) animal model, we discovered that ischemia/reperfusion (I/R)-induced brain infarction was significantly reduced by NCM, given directly into the cistern magna at the end of 90 min of CCAO/MCAO. Immunoblocking and chemical blocking strategies were applied in the in vitro ischemic studies to show that NCM supplement could protect microglia, astrocytes and neurons from GOSD-induced cell death, in a growth factor (TGFβ1, NT-3 and GDNF) and p-ERK dependent manner. Brain injection with TGFβ1, NT3, GDNF and ERK agonist (DADS) alone or in combination, therefore also significantly decreased the infarct volume of ischemic brain. Moreover, NCM could inhibit ROS but stimulate IL-1β release from GOSD-treated microglia and limit the infiltration of IL-β-positive microglia into the core area of ischemic brain, revealing the anti-oxidant and anti-inflammatory activities of NCM. In overall, NCM-mediated brain protection against cerebral ischemia has been demonstrated for the first time in S.D. rats, due to its anti-apoptotic, anti-oxidant and potentially anti-glutamate activities (NCM-induced IL-1β can inhibit the glutamate-mediated neurotoxicity) and restriction upon the infiltration of inflammatory microglia into the core area of ischemic brain. The therapeutic potentials of NCM, TGFβ1, GDNF, NT-3 and DADS in the control of cerebral ischemia in human therefore have been suggested and require further investigation.

The assessment of the efficacy of citicoline in the early and recovery stages of stroke

The review presents data on the evaluation of the efficacy of citicoline in ischemic stroke. It presents research findings about the effect of citicoline to reduce infarct volume in animal models of cerebral ischemia. Long-term treatment of CDP-choline initiated 24 hours after stroke contributes to the increased plasticity of neurons in intact brain areas (functionally associated with the damaged areas) and accelerated functional recovery. The oral administration of citicoline within the first 24 hours after the onset of symptoms in moderate and severe stroke increases the probability of complete recovery in 3 months. A neuroprotective effect of citicoline in acute and early restorative stages of stroke accompanied by cognitive impairment was shown. According to the results of clinical trials of the dosage regimen, citicoline administered in the dose of 1000 mg/day for 8 weeks accelerates the regression of hemiplegia; the intravenous injection in the dose of 750 mg/day for 10 days, starting with the first 48 hours of stroke onset symptoms, promotes the recovery of motor and cognitive functions; the intravenous injection in the dose of 1 g within 14 days improves the recovery of consciousness, general condition and functional status.

Compound K derived from ginseng: neuroprotection and cognitive improvement.

The evidence for the neuroprotective and cognitive effects of compound K, a metabolite biotransformed from ginsenosides Rb1, Rb2, and Rc, is reviewed here. Compound K is more bioavailable than other ginsenosides and therefore has greater potential to exert bioactive functions in the body. Although the capability of compound K to cross the blood-brain barrier is not clear, it has been reported to have neuroprotective and cognition enhancing effects and decrease inflammatory biomarkers in animal models of Alzheimer's disease and cerebral ischemia. The plethora of potential health benefits of compound K warrants further research to evaluate its biochemical mechanisms and its ability to protect healthy populations from neurodegenerative diseases.

Ischemic brain injury decreases dynamin-like protein 1 expression in a middle cerebral artery occlusion animal model and glutamate-exposed HT22 cells.

Dynamin-like protein I (DLP-1) is an important mitochondrial fission and fusion protein that is associated with apoptotic cell death in neurodegenerative diseases. In this study, we investigated DLP-1 expression in a focal cerebral ischemia animal model and glutamate-exposed hippocampal-derived cell line. Middle cerebral artery occlusion (MCAO) was surgically induced in adult male rats to induce focal cerebral ischemic injury. Brain tissues were collected 24 hours after the onset of MCAO. MCAO induces an increase in infarct volume and histopathological changes in the cerebral cortex. We identified a decrease in DLP-1 in the cerebral cortices of MCAO-injured animals using a proteomic approach and Western blot analysis. Moreover, glutamate treatment significantly decreased DLP-1 expression in a hippocampal-derived cell line. The decrease in DLP-1 indicates mitochondrial dysfunction. Thus, these results suggest that neuronal cell injury induces a decrease in DLP-1 levels and consequently leads to neuronal cell death.

A human neural stem cell line provides neuroprotection and improves neurological performance by early intervention of neuroinflammatory system

A human neural stem cell line, HB1.F3, demonstrated neuroprotective properties in cerebral ischemia animal models. In this study, we have investigated about the mechanisms of such neuroprotection, mainly focusing on the neuroinflammatory system at an earlier time point of the pathology. Cerebral ischemia model was generated by middle cerebral artery occlusion (MCAO) in adult male Wister rats. HB1.F3 cells were transplanted through jugular vein 6h after MCAO. Forty eight hours after MCAO, transplanted rats showed better neurological performance and decreased TUNEL positive apoptotic cell number in the penumbra. However, haematoxylin and eosin staining and immunostaining showed that, HB1.F3 cells did not affect the necrotic cell death. Twenty four hours after MCAO (18h after HB1.F3 transplantation), infiltrated granulocytes and macrophage/microglia number in the core regions were decreased compared to PBS-treated controls. Immunohistochemical analysis further demonstrated that the transplantation decreased inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2 expressing cell number in the core and penumbra, respectively. Double immunofluorescence results revealed that iNOS was mainly expressed in granulocytes and macrophage/microglia in the core region, and COX-2 mainly expressed in neurons, endothelial cells and granulocytes in penumbra. Further analysis showed that although the percentage of iNOS expressing granulocytes and macrophage/microglia was not decreased, COX-2 expressing neurons and vessel number was decreased by the transplantation. In vitro mRNA analysis showed that brain-derived neurotrophic factor (BDNF), basic fibroblast growth factor (βFGF) and bone morphogenic protein (BMP)-4 expression was high in cultured HB1.F3 cells. Thus, our results demonstrated that HB1.F3 cell transplantation provide neuroprotection possibly through the regulation of early inflammatory events in the cerebral ischemia condition.

Association between blood alcohol concentration and mortality in critical illness

ObjectiveIn animal models of renal, intestinal, liver, cardiac, and cerebral ischemia, alcohol exposure is shown to reduce ischemia-reperfusion injury. Inpatient mortality of trauma patients is shown to be decreased in a dose-dependent fashion relative to blood alcohol concentration (BAC) at hospital admission. In this study, we examined the association between BAC at hospital admission and risk of 30-day mortality in critically ill patients. DesignWe performed a 2-center observational study of patients treated in medical and surgical intensive care units in Boston, Massachusetts. SettingMedical and surgical intensive care units in 2 teaching hospitals in Boston, Massachusetts. PatientsWe studied 11850 patients, 18 years or older, who received critical care between 1997 and 2007. The exposure of interest was the BAC determined in the first 24 hours of hospital admission and categorized a priori as BAC less than 10 mg/dL (below level of detection), 10 to 80 mg/dL, 80 to 160 mg/dL, and greater than 160 mg/dL. The primary outcome was all-cause mortality in the 30 days after critical care initiation. Secondary outcomes included 90- and 365-day mortality after critical care initiation. Mortality was determined using the US Social Security Administration Death Master File, and 365-day follow-up was present in all cohort patients. Adjusted odds ratios (ORs) were estimated by multivariable logistic regression models with inclusion of covariate terms thought to plausibly interact with both BAC and mortality. Adjustment included age, sex, race (white or nonwhite), type (surgical vs medical), Deyo-Charlson index, sepsis, acute organ failure, trauma, and chronic liver disease. ResultsThirty-day mortality of the cohort was 13.7%. Compared to patients with BAC levels less than 10 mg/dL, patients with levels greater than or equal to 10 mg/dL had lower odds of 30-day mortality; for BAC levels 10 to 79.9 mg/dL, the OR was 0.53 (95% confidence interval [CI], 0.40-0.70); for BAC levels 80 to 159.9 mg/dL, it was 0.36 (95% CI, 0.26-0.49); and for BAC levels greater than or equal to 160 mg/dL, it was 0.35 (95% CI, 0.27-0.44). After multivariable adjustment, the OR of 30-day mortality was 0.97 (0.72-1.31), 0.79 (0.57-1.10), and 0.69 (0.54-0.90), respectively. When the cohort was analyzed with sepsis as the outcome of interest, the multivariable adjusted odds of sepsis in patients with BAC 80 to 160 mg/dL or greater than 160 mg/dL were 0.72 (0.50-1.04) or 0.68 (0.51-0.90), respectively, compared to those with BAC less than 10 mg/dL. In a subset of patients with blood cultures drawn (n = 4065), the multivariable adjusted odds of bloodstream infection in patients with BAC 80 to 160 mg/dL or greater than 160 mg/dL were 0.53 (0.27-1.01) or 0.49 (0.29-0.83), respectively, compared to those with BAC less than 10 mg/dL. ConclusionsAnalysis of 11850 adult patients showed that having a detectable BAC at hospitalization was associated with significantly decreased odds of 30-day mortality after critical care. Furthermore, BAC greater than 160 mg/dL is associated with significantly decreased odds of developing sepsis and bloodstream infection.

Lamotrigine attenuates cerebral ischemia-induced cognitive impairment and decreases β-amyloid and phosphorylated tau in the hippocampus in rats.

Lamotrigine (LTG) has shown benefits in animal models of cerebral ischemia, but the mechanism involved was not fully studied. This study was carried out to examine the effects of LTG on cognitive dysfunction, β-amyloid1-42 accumulation, and tau protein hyperphosphorylation in the hippocampus of ischemic rats. Transient ischemic stroke was induced by middle cerebral artery occlusion. The Morris water maze test was used to evaluate the cognitive function of rats. We found that LTG significantly attenuated ischemia-induced cognitive deficits and decreased neuronal injury in the hippocampal CA1 zone. Moreover, LTG reduced β-amyloid1-42 and phosphorylated tau (AT8) in the hippocampus after ischemia. These results suggested that the cognition-protective effects of LTG after cerebral ischemia might involve inhibition of toxic β-amyloid accumulation and tau hyperphosphorylation in the hippocampus.

European Stroke Organisation (ESO) guidelines for the management of temperature in patients with acute ischemic stroke.

Hyperthermia is a frequent complication in patients with acute ischemic stroke. On the other hand, therapeutically induced hypothermia has shown promising potential in animal models of focal cerebral ischemia. This Guideline Document presents the European Stroke Organisation guidelines for the management of temperature in patients with acute ischemic stroke. A multidisciplinary group identified related questions and developed its recommendations based on evidence from randomized controlled trials elaborating the Grading of Recommendations Assessment, Development, and Evaluation approach. This Guideline Document was reviewed within the European Stroke Organisation and externally and was approved by the European Stroke Organisation Guidelines Committee and the European Stroke Organisation Executive Committee. We found low-quality evidence, and therefore, we cannot make any recommendation for treating hyperthermia as a means to improve functional outcome and/or survival in patients with acute ischemic stroke and hyperthermia; moderate evidence to suggest against routine prevention of hyperthermia with antipyretics as a means to improve functional outcome and/or survival in patients with acute ischemic stroke and normothermia; very low-quality evidence to suggest against routine induction of hypothermia as a means to improve functional outcome and/or survival in patients with acute ischemic stroke. The currently available data about the management of temperature in patients with acute ischemic stroke are limited, and the strengths of the recommendations are therefore weak. We call for new randomized controlled trials as well as recruitment of eligible patients to ongoing randomized controlled trials to allow for better-informed recommendations in the future.

Ischemic Preconditioning: The Long-Awaited Savior of Neuroprotection. Has It Arrived?

Despite decades of research, a countless number of “neuroprotective” drugs that proved effective in animal models of stroke have failed in translational clinical trials for multiple reasons [1]. Yet, the search for the seemingly elusive neuroprotective strategy continued. Ischemic stroke is a leading cause of adult disability, and there is an unmet need to find effective neuroprotective strategies. One such strategy that has been gaining attention is ischemic tolerance and ischemic preconditioning. The phenomenon of ischemic tolerance, where brief periods of cerebral ischemia confer tolerance to subsequent ischemic challenges in the brain, has been confirmed in various animal models of cerebral ischemia. However, induction of direct brain ischemia as an effort to protect the brain presents significant challenges in the clinical setting. Thus, significant recent focus has turned to a specific form of tolerance: remote ischemic preconditioning (rIPC). In rIPC, repeated cycles of temporary ischemia in a remote organ can activate protective pathways in other organs, including the brain. This strategy presents numerous advantages over direct ischemic preconditioning, as it can be accomplished through noninvasive means without specialized equipment—typically via repeated brief periods of arm or leg ischemia using a blood pressure cuff. The cellular signaling pathways that are activated following ischemic preconditioning include: 1) adenosine release and activation of adenosine A1 receptors; 2) inhibition of glutamate release and enhancement of gamma-aminobutyric acid release thus making neurons more resistant to the excitotoxic insult; 3) amelioration of oxidative damage following cerebral ischemia through increased antioxidant production and DNA repair capacity; 4) suppression of inflammation through stimulation of Toll-like receptors, which activate many proinflammatory pathways; and 5) prevention of mitochondria-dependent cell death pathways [2, 3]. Spurred by the relatively straightforward protocols for rIPC, efforts to translate this accumulating body of knowledge and evidence supporting rIPC as a neuroprotective strategy into the clinical setting are slowly rising. Small clinical studies are ongoing to test the role of rIPC in protecting the brain against delayed ischemic injury after subarachnoid hemorrhage [4]. Recently, the value of rIPC as an adjunct therapy to thrombolysis in patients with ischemic stroke was investigated in an open-label, blinded-outcome, proof-of-concept study. The paramedics administered rIPC in the prehospital setting to 443 Danish patients with suspected acute stroke. Transient ischemic attack was more frequent, and National Institutes of Health Stroke Scale score on admission was lower in the rIPC group compared with controls. The risk of tissue infarction as assessed by diffusion–perfusion magnetic resonance imaging was also reduced in the rIPC group [5]. Another proof-of-concept study by Meng et al. [6] evaluated the protective effects of rIPC in 88 Chinese patients younger than 80 years of age with symptomatic intracranial atherosclerosis. Cerebral perfusion status, measured by single-photon emission computed tomography and transcranial Doppler, improved remarkably in patients with rIPC than in controls. In addition, the incidence of recurrent stroke at 300 days was lower and the average time to recovery (defined as modified Rankin Scale Score < 1) was shorter in the rIPC group than in controls. In this issue, Meng et al. [7] expand on their earlier study by investigating the safety and potential effectiveness of rIPC in 59 octo- and nonagenarian patients with symptomatic intracranial atherosclerosis. They conclude that rIPC safely ameliorates plasma biomarkers of inflammation and reduces stroke recurrence in these patients. Although this study is largely limited by its small sample size, it does suggest that rIPC is feasible and likely safe in older stroke patients. The studies of Meng et al. and others [5–7] indicate that rIPC holds promise as a simple and easy neuroprotective strategy for a large number of stroke patients. It is suited for 1) primary and secondary stroke prevention in multiple settings, including symptomatic and asymptomatic intra- and perhaps extracranial arterial occlusive lesions; 2) as an adjunctive strategy with or without reperfusion therapy for acute ischemic stroke; and 3) as a prophylactic strategy against delayed ischemic injury in subarachnoid hemorrhage. However, rIPC is yet to be ready for prime time. More study is needed. Although the overall findings of Meng et al. [7] and others are consistent with data from animal models and are promising, the translation into a possible clinical benefit remains to be shown in large phase III trials. In addition, the optimal timing, frequency, and duration of rIPC need to be better defined. While preclinical and early clinical studies of rIPC are promising, the potential utility of rIPC as a successful neuroprotective strategy should be viewed with cautious optimism. Have we not learned our lessons from the failure of an endless number of stroke neuroprotection studies in the past?

Rescue of Brain Function Using Tunneling Nanotubes Between Neural Stem Cells and Brain Microvascular Endothelial Cells

Evidence indicates that neural stem cells (NSCs) can ameliorate cerebral ischemia in animal models. In this study, we investigated the mechanism underlying one of the neuroprotective effects of NSCs: tunneling nanotube (TNT) formation. We addressed whether the control of cell-to-cell communication processes between NSCs and brain microvascular endothelial cells (BMECs) and, particularly, the control of TNT formation could influence the rescue function of stem cells. In an attempt to mimic the cellular microenvironment in vitro, a co-culture system consisting of terminally differentiated BMECs from mice in a distressed state and NSCs was constructed. Additionally, engraftment experiments with infarcted mouse brains revealed that control of TNT formation influenced the effects of stem cell transplantation in vivo. In conclusion, our findings provide the first evidence that TNTs exist between NSCs and BMECs and that regulation of TNT formation alters cell function.

Four-vessel occlusion model using aged male Wistar rats: a reliable model to resolve the discrepancy related to age in cerebral ischemia research.

Animal models of cerebral ischemia have typically been established and performed using young animals, even though cerebral ischemia (CI) affects primarily elderly patients. This situation represents a discrepancy that complicates the translation of novel therapeutic strategies for CI. Models of transient global CI using aged animals have demonstrated an apparent neuroprotective effect on CA1 hippocampal neurons; however, this effect is not completely understood. Our study used a model in which young (3-6months) and aged (18-21months) male Wistar rats were subjected to 15min of transient global CI using the four-vessel occlusion (4VO) model. We determined that the 4VO model can be performed on aged rats with a slight increase in mortality rate. In aged rats, the morphological damage was completely established by the 4th day after reperfusion, displaying no difference from their younger counterparts. These results demonstrated the lack of a neuroprotective effect of aging on CA1 hippocampal neurons in aged male Wistar rats. This study determined and characterized the morphological damage to the CA1 area after 15min of 4VO in aged male Wistar rats, validating the use of this model in CI and aging research.

NSC23766, A Specific Inhibitor of Rac1 GTPase, Attenuated Delayed Neuronal Cell Death and Cognitive Deficit in Rats with Cardiac Arrest

Background: Recent studies have implicated that inhibition of Rac1 GTPase protects the neuronal cells from cerebral ischemic injury, although its effects in a cardiac arrest (CA) global cerebral ischemia model have not been examined. The purpose of the current study was to examine the regulatory and functional role of the Rac1 in reactive oxygen species (ROS) generation and neuronal cell death/cognitive dysfunction following global cerebral ischemia in the rats.Methods: A rat model of CA was established by the delivery of alternating current between the esophagus and chest wall to induce ventricular fibrillation. Rats were randomly assigned to the following groups: 1) sham group, 2) CA group, 3) CA + NSC23766 group (NSC), and 4) CA + saline group. NSC23766 (50 μg, intracerebroventricular injection) or isotonic saline was administered 15 minutes before CA. Neurological function of rats after reperfusion was scored using the neurological deficit score evaluation method. Survival rates, neuronal counts, Rac1 activation, mitochondrial ROS formation and expression of thioredoxin2 (Trx2) and peroxiredoxin3 (Prx3) in the hippocampal CA1 region were assessed after reperfusion. Morris water maze task was used to quantify spatial learning and memory deficits after reperfusion.Results: NSC23766, the specific inhibitor of Rac1 GTPase, significantly attenuated neuronal damage and reduced the spatial learning and memory deficits associated with global cerebral ischemia induced by CA (P<0.05). Furthermore, NSC23766 exerted its neuroprotective function by decreasing the ROS generation (P<0.05). However, there was no significant difference of Trx2 and Prx3 protein expression in hippocampal CA1 region between the CA group and NSC group after 1 day reperfusion (P<0.05). Conclusions: Our findings suggested that NSC23766 not only ameliorated post-ischemic neuronal cell death, but also improved learning and memory deficits in a cerebral ischemia animal model through down-regulating ROS generation. Citation: Juan Liao, Chang Xu, Chang Liu, Na Wang, Guo-Qing Huang, Chang-Sheng Huang, et al. NSC23766, a specific inhibitor of Rac1 GTPase, attenuated delayed neuronal cell death and cognitive deficit in rats with cardiac arrest. J Anesth Perioper Med 2015; 2: 136-45. doi: 10.24015/JAPM.2015.0019This is an open-access article, published by Evidence Based Communications (EBC). This work is licensed under the Creative Commons Attribution 4.0 International License, which permits unrestricted use, distribution, and reproduction in any medium or format for any lawful purpose. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

The protective effect of caffeic acid on global cerebral ischemia-reperfusion injury in rats.

Ischemic stroke is a major cause of death and disability all over the world. Ischemic stroke results from a temporary or permanent reduction of cerebral blood flow that leads to functional and structural damage in different brain regions. Despite decades of intense research, the beneficial treatment of stroke remains limited. In light of this, the search for effective means ameliorating cerebral ischemia-reperfusion injury (CIRI) is one of the major problems of experimental medicine and biology. Recently, the 5-Lipoxygenase (5-LO, a key enzyme metabolizing arachidonic acid to produce leukotrienes) inhibitors have been showed to protect brain against ischemic damage in animal model of cerebral ischemia. Caffeic acid, an inhibitor of 5-LO, is a phenolic compound widely distributed in medicinal plants. The aim of this study was to investigate the effect of caffeic acid on global cerebral ischemia-reperfusion injury in rats. The study was carried out on 45 rats that were randomly divided into five groups: the sham group (n = 9), I/R non-treated group (n = 9), I/R-caffeic acid group (10 mg · kg−1) (n = 9), I/R-caffeic acid group (30 mg · kg−1) (n = 9) and I/R-caffeic acid group (50 mg · kg−1) (n = 9). Global cerebral ischemia was induced by bilateral carotid artery occlusion for 20 min followed by reperfusion. Spatial learning and memory was evaluated using Morris water maze. Histopathological changes of hippocampus neurons was observed using HE staining. Superoxide dismutase (SOD, the antioxidant enzyme) activities and malondialdehyde (MDA, an oxidative stress biomarker) contents were detected. NF-κBp65 expression was detected by the methods of immunohistochemistry. Caffeic acid markedly reduced the escape latency, relieved hippocampal neurons injury and increased neuron count compared with those of I/R non-treated rat. NF-κBp65 expression and MDA content decreased significantly, and SOD activities increased significantly in hippocampus. Compared with sham group, 5-LO expression increase significantly in I/R non-treated group rat, and caffeic acid markedly reduced 5-LO expression. The results of the study suggest that caffeic acid has a significant protective effect on global cerebral ischemia-reperfusion injury in rats. The neuroprotective effects is likely to be mediated through the inhibition of 5-LO.

Perspective of synaptic protection after post-infarction treatment with statins.

Stroke is the second most common cause of death in people over 45 years of age in Colombia and is the leading cause of permanent disability worldwide. Cerebral ischemia is a stroke characterized by decreased blood flow due to the occlusion of one or more cerebral arteries, which can cause memory problems and hemiplegia or paralysis, among other impairments. The literature contains hundreds of therapies (invasive and noninvasive) that exhibit a neuroprotective effect when evaluated in animal models. However, in clinical trials, most of these drugs do not reproduce the previously demonstrated neuroprotective property, and some even have adverse effects that had not previously been detected in animal experimentation.Statins are drugs that inhibit 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, the rate-limiting enzyme in cholesterol synthesis. Several studies have shown that statin therapy in an animal model of focal cerebral ischemia reduces infarct volume, as well as markers of neurodegeneration, activates neuronal survival pathways, and improves performance on learning and memory tests. Given the implied therapeutic benefit and the limited understanding of the mechanism of action of statins in brain repair, it is necessary to address the biochemical and tissue effects of these drugs on synaptic proteins, such as NMDA receptors, synaptic adhesion proteins, and cytoskeletal proteins; these proteins are highly relevant therapeutic targets, which, in addition to giving a structural account of synaptic connectivity and function, are also indicators of cellular communication and the integrity of the blood–brain barrier, which are widely affected in the long term post-cerebral infarct but, interestingly, are protected by statins when administered during the acute phase.

Synthesis and Evaluation of 3-(furo[2,3-b]pyridin-3-yl)-4-(1H-indol-3-yl)-maleimides as Novel GSK-3β Inhibitors and Anti-Ischemic Agents.

A series of novel 3-(furo[2,3-b]pyridin-3-yl)-4-(1H-indol-3-yl)-maleimides were designed, synthesized, and biologically evaluated for their GSK-3β inhibitory activities. Most compounds showed favorable inhibitory activities against GSK-3β protein. Among them, compounds 5n, 5o, and 5p significantly reduced GSK-3β substrate tau phosphorylation at Ser396 in primary neurons, indicating inhibition of cellular GSK-3β activity. In the invitro neuronal injury models, compounds 5n, 5o, and 5p prevented neuronal death against glutamate, oxygen-glucose deprivation, and nutrient serum deprivation which are closely associated with cerebral ischemic stroke. In the invivo cerebral ischemia animal model, compound 5o reduced infarct size by 10% and improved the neurological deficit. The results may provide new insights into the development of novel GSK-3β inhibitors with potential neuroprotective activity against brain ischemic stroke.

Focal embolic cerebral ischemia in the rat.

Animal models of focal cerebral ischemia are well accepted for investigating the pathogenesis and potential treatment strategies for human stroke. Occlusion of the middle cerebral artery (MCA) with an endovascular filament is a widely used model to induce focal cerebral ischemia. However, this model is not amenable to thrombolytic therapies. As thrombolysis with recombinant tissue plasminogen activator (rtPA) is a standard of care within 4.5 h of human stroke onset, suitable animal models that mimic cellular and molecular mechanisms of thrombosis and thrombolysis of stroke are required. By occluding the MCA with a fibrin-rich allogeneic clot, we previously developed an embolic model of MCA occlusion in the rat, which recapitulates the key components of thrombotic development and of thrombolytic therapy of rtPA observed from human ischemic stroke. Here we describe in detail the surgical procedures of our model, including preparing emboli from rat donors. These procedures can be typically completed within ∼30 min, and they are highly adaptable to other strains of rats, as well as mice, in both sexes. Thus, this model provides a powerful tool for translational stroke research.

MCP-induced protein 1 mediates the minocycline-induced neuroprotection against cerebral ischemia/reperfusion injury in vitro and in vivo.

BackgroundMinocycline, a broad-spectrum tetracycline antibiotic, has shown anti-inflammatory and neuroprotective effects in ischemic brain injury. The present study seeks to determine whether monocyte chemotactic protein-induced protein 1 (MCPIP1), a recently identified modulator of inflammatory reactions, is involved in the cerebral neuroprotection conferred by minocycline treatment in the animal model of focal cerebral ischemia and to elucidate the mechanisms of minocycline-induced ischemic brain tolerance.MethodsFocal cerebral ischemia was induced by middle cerebral artery occlusion (MCAO) for 2 h in male C57BL/6 mice and MCPIP1 knockout mice followed by 24- or 48-h reperfusion. Twelve hours before ischemia or 2 h after MCAO, mice were injected intraperitoneally with 90 mg/kg of minocycline hydrochloride. Thereafter, the animals were injected twice a day, at a dose of 90 mg/kg after ischemia until sacrificed. Transcription and expression of MCPIP1 gene was monitored by quantitative real-time PCR (qRT-PCR), Western blot, and immunohistochemistry. The neurobehavioral scores, infarction volumes, and proinflammatory cytokines in brain and NF-κB signaling were evaluated after ischemia/reperfusion.ResultsMCPIP1 protein and mRNA levels significantly increased in mouse brain undergoing minocycline pretreatment. Minocycline treatment significantly attenuated the infarct volume, neurological deficits, and upregulation of proinflammatory cytokines in the brain of wild type mice after MCAO. MCPIP1-deficient mice failed to evoke minocycline-treatment-induced tolerance compared with that of the control MCPIP1-deficient group without minocycline treatment. Similarly, in vitro data showed that minocycline significantly induced the expression of MCPIP1 in primary neuron-glial cells, cortical neurons, and reduced oxygen glucose deprivation (OGD)-induced cell death. The absence of MCPIP1 blocked minocycline-induced protection on neuron-glial cells and cortical neurons treated with OGD.ConclusionsOur in vitro and in vivo studies demonstrate that MCPIP1 is an important mediator of minocycline-induced protection from brain ischemia.

Abstract T P27: Early Blood Brain Barrier Disruption in the Ischemic Core

Background: Animal models of cerebral ischemia have identified an early, reversible opening of the blood brain barrier (BBB) which is separate from the delayed secondary opening caused by neuroinflamation. A recent study found BBB disruption was frequently detected in acute ischemic stroke patients with MRI permeability imaging (Leigh et al., Stroke, 2014). Hypothesis: More severe restricted diffusion will be associated with higher degrees of BBB damage in acute ischemic stroke patients. Methods: The MRI scans of 13 acute ischemic stroke patients were analyzed. Diffusion weighted images (DWI) and perfusion weighted images (PWI) where co-registered to allow for a voxel based analysis. Blood-brain permeability images (BBPI) were generated from the PWI source images as described in the aforementioned study. Only voxels of tissue which had an apparent diffusion coefficient (ADC) &lt; 700 were included. Linear regression was performed to determine if there was a relationship between ADC and BBPI. Results: From the 13 patients, 535 mL of brain tissue was included in the analysis. The figure shows a scatter plot and regression line of ADC value vs mean fraction of gadolinium leakage on BBPI. Univariate linear regression with ADC as the independent variable and BBPI as the dependent variable found them to be significantly correlated (p&lt;0.001). Multivariate analysis found time-to-MRI (p&lt;0.001) but not patient age (p=0.71) to be significantly correlated with BBPI in addition to ADC (p&lt;0.001). Conclusions: Early BBB damage was detected within the ischemic core of acute stroke patients. The degree of restricted diffusion was significantly correlated with the degree of BBB damage.

A systematic review and meta-analysis of Ginsenoside-Rg1 (G-Rg1) in experimental ischemic stroke.

The neuroprotective actions of Ginsenoside-Rg1 (G-Rg1) have been documented for experimental stroke therapy. We used a systematic review and meta-analysis to assess the efficacy of G-Rg1 in experimental ischemic stroke. We identified studies describing the efficacy of G-Rg1 in animal models of focal cerebral ischemia. Primary outcomes were infarct volume and neurological function score (NFS). In all, eleven studies reported significant effects of G-Rg1 for improving the NFS when compared with the control group (P<0.00001), and four studies reported significant effects of G-Rg1 for reducing infarct volume compared with middle cerebral artery occlusion group (P<0.00001). Meanwhile, studies reported G-Rg1 was more efficacious than positive control drug nimodipine (0.7 or 1 mg/kg, intraperitoneal) according to NFS (P = 0.009) and infarct volume (p = 0.0002). The results demonstrate a marked efficacy of G-Rg1 in experimental acute ischemic stroke, but raise concerns that our value of effect size might be overestimate due to factors such as study quality and possible publication bias. Even so, the findings suggest G-Rg1 as a candidate neuroprotective drug for human ischemic stroke.