Brain Infarct Size Research Articles

Higenamine reduces HMGB1 during hypoxia-induced brain injury by induction of heme oxygenase-1 through PI3K/Akt/Nrf-2 signal pathways

Growing lines of evidence suggests that high mobility group box-1 (HMGB1) plays an important role for promoting inflammation and apoptosis in brain ischemia. Previously, we demonstrated that inducers of heme oxygenase-1 (HO-1) significantly reduce HMGB1 release in inflammatory conditions in vitro and in vivo. Thus, we tested our hypothesis that higenamine protects brain injury by inhibition of middle cerebral artery occlusion (MCAO)-mediated HMGB1 release in vivo, and glucose/glucose oxidase (GOX)-induced apoptosis in C6 cells in vitro due to HO-1 induction. Higenamine increased HO-1 expression in C6 cells in both hypoxia and normoxia, in which the former was much more significant than the latter. Higenamine increased Nrf-2 luciferase activity, translocated Nrf-2 to nucleus, and increased phosphorylation of Akt in C6 cells. Consistent with this, LY 294002, a PI3K inhibitor, inhibited HO-1 induction by higenamine and apoptosis induced by glucose/GOX in C6 cells was prevented by higenamine, which effect was reversed by LY 294002. Importantly, administration of higenamine (i.p) significantly reduced brain infarct size, mortality rate, MPO activity and tissue expression of HMGB1 in MCAO rats. In addition, recombinant high mobility group box 1 induced apoptosis in C6 cells by increasing ratio of Bax/bcl-2 and cleaved caspase c, which was inhibited by higenamine, and all of these effects were reversed by co-treatment with ZnPPIX. Therefore, we conclude that higenamine, at least in part, protects brain cells against hypoxic damages by up-regulation of HO-1. Thus, higenamine may be beneficial for the use of ischemic injuries such as stroke.

Effect of Baweichenxiang powder on acute hypoxic cerebral ischemia-reperfusion injury in rats

Objective To observe the protection of Baweichenxiang powder on cerebral ischemia-reperfusion injury in rats.Methods SD rats were randomly divided into six groups,namely,sham operation group,model group,nimodipine group,Baweichenxiang powder high,medium and low-dose group.Cerebral ischemia-reperfusion rat model was established by gavage.Observe the effects of different doses of Baweichenxiang powder on behavior in rats,brain water content,infarct size,SOD,MDA and morphological changes.Results Compared with the control group,Baweichenxiang powder significantly reduced behavioral score (P＜0.05),reduced brain edema,decreased infarct size,improved brainmorphological changes,increased SOD activity(P＜0.05,P＜0.01)and reduced the MDA content(P＜0.05).Conclusion Baweichenxiang powder of high dose and middle dose have significant protective effect for cerebral ischemia,the mechanism may be related to its improving levels of free radicals and lipid peroxidation. Key words: Baweichenxiang powder; Cerebral ischemia and reperfusion; Free

(S)-ZJM-289, a nitric oxide-releasing derivative of 3-n-butylphthalide, protects against ischemic neuronal injury by attenuating mitochondrial dysfunction and associated cell death

Pharmacological compounds that release nitric oxide (NO) have been recognized as the potential therapeutic agents for acute stroke. (S)-ZJM-289 is a novel NO-releasing derivative of 3-n-butylphthalide (NBP) with enhanced anti-platelet and anti-thrombotic actions. The present study was performed to investigate the neuroprotective effects and related mechanisms of (S)-ZJM-289 on ischemic neuronal injury in vitro and in vivo. Primary cortical neuronal cultures were exposured to oxygen–glucose deprivation followed by recovery (OGD/R), a model of ischemia-like injury, and treated with (S)-ZJM-289 before OGD. In vitro results showed that (S)-ZJM-289 attenuated OGD/R-induced neuronal injury, which was associated with the maintenance of mitochondrial integrity and function by alleviating intracellular calcium overload and reactive oxygen species (ROS) accumulation, preventing mitochondrial membrane depolarization and preserving respiratory chain complexes activities. Moreover, (S)-ZJM-289 treatment suppressed mitochondrial release of cytochrome c (cyt c) and nuclear translocation of apoptosis-inducing factor (AIF), thereby blocking mitochondria-mediated cell death, which may be partially mediated by up-regulation of Hsp70. The neuroprotection by (S)-ZJM-289 was also studied using a model of middle cerebral artery occlusion (MCAO). Oral administration of (S)-ZJM-289 at the onset of reperfusion for 3d significantly reduced the brain infarct size, improved neurological deficit and prevented neuronal loss and apoptosis. In current study, (S)-ZJM-289 appears to be more potent in ischemic neuroprotection than NBP, in particular at the lower doses, which may be due to the synergistic action of NBP and NO. These findings point to that (S)-ZJM-289 could be an attractive alternative to NBP in preventing the process of ischemia/reperfusion (I/R) injury.

Abstract 8534: Combination of Cyclosporine and Erythropoietin Improves Brain Infarct Size and Neurological Function in Rats after Ischemic Stroke

Objectives: This study tested the superiority of combined cyclosporine (CsA)-erythropoietin (EPO) therapy compared with either one in limiting brain infarction area (BIA) and preserving neurological function in rat after ischemic stroke (IS). Methods: Fifty adult-male SD rats were equally divided into sham control (group 1), IS plus intra-peritoneal physiological saline (at 0.5/24/48h after IS) (group 2), IS plus CsA (20.0 mg/kg at 0.5/24h, intra-peritoneal) (group 3), IS plus EPO (5,000IU/kg at 0.5/24/48h, subcutaneous) (group 4), combined CsA and EPO treatment (group 5) after occlusion of distal left internal carotid artery. Results: BIA on day 21 after acute IS was highest in group 2 and lowest in group 5 (all p<0.01). The sensorimotor functional test showed highest frequency of left turning in group 2 and lowest in group 5 (all p<0.05). mRNA and protein expressions of apoptotic markers and number of apoptotic nuclei on TUNEL were highest in group 2 and lowest in group 1 and 5, whereas the anti-apoptotic markers exhibited an opposite trend (all p<0.05). The expressions of inflammatory and oxidized protein were highest in group 2 and lowest in group 1 and 5, whereas anti-inflammatory markers showed reversed changes in group 1 and 5 (all p<0.05). The number of aquaporin - 4+ and glial fibrillary acid protein+ stained cells were highest in group 2 and lowest in groups 1 and 5 (all p<0.01). Conclusion: Combined treatment with CsA and EPO was superior to either one alone in protecting rat brain from ischemic damage after IS (the proposed mechanisms of potential therapeutic impact of combined therapy with CsA and EPO on acute IS have been summarized in the figure)

Abstract 8694: Phosphodiesterase 3 Inhibitor Prevents Thrombotic Diseases Without Affecting Hemostatic Function

Introduction: Conventional anti-platelet therapy is associated with increased risk of bleeding. Recently, the results of the second Cilostazol Stroke Prevention Study (CSPS 2) showed similar efficacy but fewer hemorrhagic events with the phosphodiesterase (PDE)3 inhibitor cilostazol vs. aspirin. Hypothesis: We hypothesized that PDE3 inhibition reduces thrombus formation without affecting hemostasis, and leads to beneficial effects in experimental cerebral infarction and peripheral artery disease (PAD) models Methods: We used a cilostazol analog, K-134, as a more potent and selective PDE3 inhibitor. To evaluate the anti-thrombus activity of K-134, we measured mortality rate in a pulmonary embolism model established by collagen infusion into mice via the tail vein 10 min after oral administration of K-134. We also studied its influence on tail vein bleeding times. To investigate whether K-134 can ameliorate other thrombotic diseases, we established a rat cerebral infarction model by photochemically induced thrombosis-mediated occlusion of middle cerebral arteries and a PAD model by laurate injection-mediated peripheral arterial injury. Pathological signs in the areas of necrosis in the hind legs in the PAD model were classified as Grade 0 to 5. Results: K-134 decreased mortality in the mouse pulmonary embolism model when orally administered at 3, 10, and 30 mg/kg ( n = 29-30, P < 0.01 vs. control, ED50 = 2.1 mg/kg) but did not prolong bleeding time even at 100 mg/kg compared to control ( n = 30, 98 ± 6 vs. 84 ± 7 s., not significant). In contrast, warfarin prolonged bleeding time ( n = 29-30, 139 ± 7 vs. 84 ± 7 s., P < 0.01). Preoperative administration of K-134 at 30 mg/kg reduced brain infarct size compared to control in the rat cerebral infarction model ( n = 12, 87.5 ± 5.6 vs. 126.8 ± 7.5 mm 3 , P < 0.01). Furthermore, 30 mg/kg K-134 inhibited the progression of lesions compared with controls in the PAD model ( n = 12-15, mean grade of pathological sign: 2.3 ± 0.2 vs. 3.5 ± 0.3, P < 0.05). Conclusion: PDE3 inhibition is an attractive approach for the secondary prevention of cerebral infarction and treatment of peripheral arterial disease.

Polydatin modulates inflammation by decreasing NF-κB activation and oxidative stress by increasing Gli1, Ptch1, SOD1 expression and ameliorates blood–brain barrier permeability for its neuroprotective effect in pMCAO rat brain

Inflammation and oxidative stress play an important role in cerebral ischemic pathogenesis. Polydatin has been proved to elicit numerous biological effects through its anti-inflammatory and anti-oxidant properties. However, little is known regard to the mechanism of polydatin's neuroprotection in ischemic stroke. We therefore investigated the potential neuroprotective effects of polydatin and explored the underlying mechanisms. Male, Sprague-Dawley rats were subjected to permanent middle cerebral artery occlusion (pMCAO). Experiment 1 was used to evaluate the expression of glioma-associated oncogene homolog1 (Gli1), Patched-1 (Ptch1) and Superoxide dismutase 1 (SOD1) after pMCAO, six time points were included. Experiment 2 was used to detect polydatin's neuroprotection after pMCAO. Neurological deficit, brain water content and infarct size were measured at 24h and 72 h after pMCAO. Immunohistochemistry, reverse transcription-polymerase chain reaction (RT-PCR), Western Blotting, activity assay and confocal microscope were used to analyse the expression of Gli1, Ptch1, SOD1 and nuclear factor-kappa B (NF-κB). Experiment 3 was used to detect polydatin's influence on blood-brain barrier (BBB). Compared with Sham group, the expression of Gli1, Ptch1 and SOD1 were up-regulated shortly after pMCAO (P<0.05). Compared with Vehicle group, high dose of polydatin (50mg/kg) up-regulated Gli1, Ptch1, SOD1 and down-regulated NF-κB, and reduced infarct volume, brain water content and behavioral deficits (P<0.05). Meanwhile, BBB permeability was also ameliorated. The results indicated that polydatin protected the brain from damage caused by pMCAO, and this effect may be through up-regulating the expression of Gli1, Ptch1 and SOD1 and down-regulating the expression of NF-κB, and ameliorating BBB permeability.

Hyperglycemia promotes tissue plasminogen activator‐induced hemorrhage by Increasing superoxide production

Risk of intracerebral hemorrhage is the primary factor limiting use of tissue plasminogen activator (tPA) for stroke. Clinical studies have established an association between admission hyperglycemia and the risk of hemorrhage with tPA use, independent of prior diabetes. Here we used an animal model of tPA-induced reperfusion hemorrhage to determine if this clinical association reflects a true causal relationship. Rats underwent 90 minutes of focal ischemia, and tPA infusion was begun 10 minutes prior to vessel reperfusion. Glucose was administered during ischemia to generate blood levels ranging from 5.9 ± 1.8mM (normoglycemia) to 21 ± 2.3mM. In some studies, apocynin was administered to block superoxide production by nicotinamide adenine dinucleotide phosphate (NADPH). Brains were harvested 1 hour or 3 days after reperfusion to evaluate the effects of hyperglycemia and apocynin on oxidative stress, blood-brain barrier breakdown, infarct volume, and hemorrhage volume. Rats that were hyperglycemic during tPA infusion had diffusely increased blood-brain barrier permeability in the postischemic territory, and a 3- to 5-fold increase in intracerebral hemorrhage volumes. The hyperglycemic rats also showed increased superoxide formation in the brain parenchyma and vasculature during reperfusion. The effects of hyperglycemia on superoxide production, blood-brain barrier disruption, infarct size, and hemorrhage were all attenuated by apocynin. These findings demonstrate a causal relationship between hyperglycemia and hemorrhage in an animal model of tPA stroke treatment, and suggest that this effect of hyperglycemia is mediated through an increase in superoxide production by NADPH oxidase.

Combination of cyclosporine and erythropoietin improves brain infarct size and neurological function in rats after ischemic stroke

BackgroundThis study tested the superiority of combined cyclosporine A (CsA)-erythropoietin (EPO) therapy compared with either one in limiting brain infarction area (BIA) and preserving neurological function in rat after ischemic stroke (IS).MethodsFifty adult-male SD rats were equally divided into sham control (group 1), IS plus intra-peritoneal physiological saline (at 0.5/24/48 h after IS) (group 2), IS plus CsA (20.0 mg/kg at 0.5/24h, intra-peritoneal) (group 3), IS plus EPO (5,000IU/kg at 0.5/24/48h, subcutaneous) (group 4), combined CsA and EPO (same route and dosage as groups 3 and 4) treatment (group 5) after occlusion of distal left internal carotid artery.ResultsBIA on day 21 after acute IS was higher in group 2 than in other groups and lowest in group 5 (all p < 0.01). The sensorimotor functional test showed higher frequency of left turning in group 2 than in other groups and lowest in group 5 (all p < 0.05). mRNA and protein expressions of apoptotic markers and number of apoptotic nuclei on TUNEL were higher in group 2 than in other groups and lowest in group 1 and 5, whereas the anti-apoptotic markers exhibited an opposite trend (all p < 0.05). The expressions of inflammatory and oxidized protein were higher in group 2 than in other groups and lowest in group 1 and 5, whereas anti-inflammatory markers showed reversed changes in group 1 and other groups (all p < 0.05). The number of aquaporin-4+ and glial fibrillary acid protein+ stained cells were higher in group 2 as compared to other groups and lowest in groups 1 and 5 (all p < 0.01).Conclusioncombined treatment with CsA and EPO was superior to either one alone in protecting rat brain from ischemic damage after IS.

Remote Ischemic Per-Conditioning

Remote ischemic preconditioning is a phenomenon by which a short period of sublethal ischemia to an organ protects against subsequent ischemia in another organ. We have recently demonstrated that remote ischemic conditioning by transient hind limb ischemia delivered during ischemia and before reperfusion can provide potent cardioprotection, a phenomenon we termed per-conditioning. This study evaluated whether remote ischemic per-conditioning may provide neuroprotection in a clinically relevant rat model of acute ischemic stroke. Remote ischemic conditioning by transient limb ischemia was used in a rat transient middle cerebral artery occlusion model of acute stroke. A total of 39 P60 rats were randomly allocated to receive preconditioning, per-conditioning, or sham conditioning. Cerebral ischemia was maintained for 120 minutes followed by reperfusion. The resulting infarct size at 24 hours was quantified using computerized image analysis of 2-3-5-triphenyl tetrazolium chloride-stained brain sections. Compared with control, both pre- and per-conditioning significantly reduced brain infarct size with the more clinically relevant per-conditioning stimulus being superior to preconditioning. Remote per-conditioning by transient limb ischemia is a facile, clinically relevant stimulus that provides potent neuroprotection in a model of regional brain ischemia-reperfusion injury. Further studies are required to better understand the mechanisms and biology of this response before translation to randomized controlled trials of remote per-conditioning for acute ischemic stroke.

Therapy with recombinant T-cell receptor ligand reduces infarct size and infiltrating inflammatory cells in brain after middle cerebral artery occlusion in mice

Stroke induces a biphasic effect on the peripheral immune response that involves early activation of peripheral leukocytes followed by severe immunosuppression and atrophy of the spleen. Peripheral immune cells, including T lymphocytes, migrate to the brain and exacerbate the developing infarct. Recombinant T-cell receptor (TCR) Ligand (RTL)551 is designed as a partial TCR agonist for myelin oligodendrocyte glycoprotein (MOG)-reactive T cells and has demonstrated the capacity to limit infarct volume and inflammation in brain when administered to mice undergoing middle cerebral artery occlusion (MCAO). The goal of this study was to determine if RTL551 could retain protection when given within the therapeutically relevant 4 h time window currently in clinical practice for stroke patients. RTL551 was administered subcutaneously 4 h after MCAO, with repeated doses every 24 h until the time of euthanasia. Cell numbers were assessed in the brain, blood, spleen and lymph nodes and infarct size was measured after 24 and 96 h reperfusion. RTL551 reduced infarct size in both cortex and striatum at 24 h and in cortex at 96 h after MCAO and inhibited the accumulation of inflammatory cells in brain at both time points. At 24 h post-MCAO, RTL551 reduced the frequency of the activation marker, CD44, on T-cells in blood and in the ischemic hemisphere. Moreover, RTL551 reduced expression of the chemokine receptors, CCR5 in lymph nodes and spleen, and CCR7 in the blood and lymph nodes. These data demonstrate effective treatment of experimental stroke with RTL551 within a therapeutically relevant 4 h time window through immune regulation of myelin-reactive inflammatory T-cells.

Glial Cells Drive Preconditioning-Induced Blood-Brain Barrier Protection

The cerebrovascular contribution to ischemic preconditioning (IPC) has been scarcely explored. Using in vivo and in vitro approaches, we investigated the involvement of the blood-brain barrier and the role of its cellular components. Seven-minute occlusion of the right middle cerebral artery, used as in vivo IPC stimulus 4 days before permanent occlusion of the right middle cerebral artery, significantly reduced brain infarct size (8.45±0.7 versus 13.61±0.08 mm3 measured 7 days after injury) and preserved blood-brain barrier function (Evans blue leakage, 0.54±0.1 versus 0.89±0.1 ng/mg). Assessment of neuronal, endothelial, and glial gene expression revealed that IPC specifically increased glial fibrillary acidic protein mRNA, thus showing selective astrocyte activation in IPC-protected mice. The blood-brain barrier was modeled by coculturing murine primary brain microvessel endothelial and astroglial cells. One-hour oxygen-glucose deprivation (OGD), delivered 24 hours before a 5-hour OGD, acted as an IPC stimulus, significantly attenuating the reduction in transendothelial electric resistance (199.17±11.7 versus 97.72±3.4 Ωcm2) and the increase in permeability coefficients for sodium fluorescein (0.98±0.11×10(-3) versus 1.8±0.36×10(-3) cm/min) and albumin (0.12±0.01×10(-3) versus 0.29±0.07×10(-3) cm/min) induced by severe OGD. IPC also prevented the 5-hour OGD-induced disorganization of the tight junction proteins ZO-1 and claudin-5. IPC on glial (but not endothelial) cells alone preserved transendothelial electric resistance, permeability coefficients, and ZO-1 localization after 5 hours of OGD. Astrocyte metabolic inhibition by fluorocitrate abolished IPC protection, confirming the critical role of astrocytes. IPC significantly increased glial fibrillary acidic protein, interleukin-6, vascular endothelial growth factor-a, and ciliary neurotrophic factor gene expression after OGD in glial cells, indicating that multiple pathways mediate the glial contribution to IPC. Our data show that the blood-brain barrier can be directly preconditioned and that astrocytes are major mediators of IPC protection.

Vascular expression, activity and function of indoleamine 2,3-dioxygenase-1 following cerebral ischaemia–reperfusion in mice

Indoleamine 2,3-dioxygenases-1 (Ido1) and -2 initiate the kynurenine pathway of tryptophan metabolism. In addition to the established immune regulatory effects of Ido1 and the ability of nitric oxide to regulate Ido1 activity, it is now also known that Ido1-mediated metabolism of tryptophan to kynurenine can modulate vascular tone. Ido activity is reportedly elevated in stroke patients and correlates with increased risk of death. Thus, the present goals were to test whether, following cerebral ischaemia, Ido activity and cerebrovascular Ido1 expression are altered and whether expression of Ido1 contributes to stroke outcome. Transient cerebral ischaemia was induced in wild-type and Ido1 gene-deficient (Ido1 (-/-)) mice. Mice were pre-treated with vehicle, the Ido1 inhibitor, 1-methyl-D-tryptophan (1-MT; 50 mg/kg i.p.) or the inducible nitric oxide synthase (Nos2) inhibitor, aminoguanidine (AG, 100 mg/kg i.p.). At 24 h, neurological function, brain infarct size and swelling were assessed. In addition, Ido activity was estimated by plasma kynurenine and tryptophan, and Ido1 expression was examined in cerebral arterioles. Cerebral ischaemia-reperfusion in wild-type mice increased Ido activity and its expression in cerebral arterioles. Ido1 (-/-) and 1-MT-treated wild-type mice had lower Ido activity but similar post-stroke neurological function and similar total brain infarct volume and swelling, relative to control mice. Inhibition of Nos2 with AG also did not affect Ido activity or outcome following stroke. This study provides molecular and pharmacological evidence that the expression and the activity of Ido1 increase following stroke. However, such Ido1 expression does not appear to affect overall outcome following acute ischaemic stroke, and furthermore, a regulatory role of Nos2-derived nitric oxide on Ido activity following cerebral ischaemia-reperfusion appears unlikely.

Nicotine aggravates the brain postischemic inflammatory response

A substantial body of evidence suggests that nicotine adversely affects cerebral blood flow and the blood-brain barrier and is a risk factor for stroke. The present study investigated the effect of nicotine on cerebrovascular endothelium under basal and ischemia/reperfusion injury under in vivo condition. Nicotine (2 mg/kg sc) was administered to mice over 14 days, which resulted in plasma nicotine levels of ∼100 ng/ml, reflecting plasma concentrations in average to heavy smokers. An analysis of the phenotype of isolated brain microvessels after nicotine exposure indicated higher expression of inflammatory mediators, cytokines (IL-1β, TNF-α, and IL-18), chemokines (CCL2 and CX(3)CL1), and adhesion molecules (ICAM-1, VCAM-1, and P-selectins), and this was accompanied by enhanced leukocyte infiltration into brain during ischemia/reperfusion (P < 0.01). Nicotine had a profound effect on ischemia/reperfusion injury; i.e., increased brain infarct size (P < 0.01), worse neurological deficits, and a higher mortality rate. These experiments illuminate, for the first time, how nicotine regulates brain endothelial cell phenotype and postischemic inflammatory response at the brain-vascular interface.

Effect of erythropoietin therapy on clinical outcome in patients after acute ischemic stroke: a debatable issue

Clinical studies have shown a link between an increased number of circulating endothelial progenitor cells (EPCs) and a favorable clinical outcome in patients after acute ischemic stroke (IS). Basic researches and animal model studies have established that erythropoietin (EPO) therapy enhances angiogenesis, reduces brain infarction size and improves ischemia-related organ dysfunction. It is, therefore, rational to hypothesize that EPO therapy may improve the neurological outcome of patients after acute IS through enhancing the mobilization of EPCs from bone marrow to circulation, thereby promoting angiogenesis in ischemic region.

Postconditioning in focal cerebral ischemia: Role of the mitochondrial ATP-dependent potassium channel

Introduction Ischemic postconditioning (IpostC) has been described in both heart and brain. The first aim of this study was to evaluate the effects of IpostC on brain infarct size and neurological function in the middle cerebral artery occlusion (MCAO) model. The second aim was to determine the involvement of the mitochondrial potassium ATP-dependent channel (mitoK ATP) opening and its capacity to improve mitochondrial dysfunction induced by ischemia–reperfusion. Methods Wistar rats were subjected to 60 min MCAO followed by 24-h reperfusion. Postconditioning was performed by 3 cycles of 30-s occlusion–reperfusion at the onset of reperfusion. Three behavioral tests were performed following 24 h of reperfusion. Involvement of mitoK ATP was determined by the modulation of IpostC effects by 5-hydroxydecanoate (5-HD) and diazoxide. Mitochondrial function after 24 h of reperfusion on isolated mitochondria was assessed through mitochondrial oxygen consumption, mitochondrial membrane potential and calcium retention capacity to evaluate impact of IpostC on mitochondrial permeability transition pore (MPTP) opening. Results IpostC resulted in a 40% decrease in infarct size and improved neurological outcome. These effects were lost when IpostC was delayed by 5 min. The administration of diazoxide resulted in a 60% in infarct size. The beneficial effects of IpostC and diazoxide were blocked by 5-HD. Furthermore, 5-HD also blocked the inhibition of MPTP opening by IpostC and diazoxide. The hyperpolarization induced by ischemia–reperfusion was corrected by IpostC without any effect on oxidative phosphorylation. Conclusion Our results confirm ischemic postconditioning-induced neuroprotection. They also support the involvement of mitoK ATP opening and its role in inhibiting the opening of MTPT induced by postconditioning.

Protective effect of etomidate postcoditioning on cerebral ischemia- reperfusion injury in rats

Objective To observe the protective effect of etomidate postcoditioning on transient focal cerebral ischemiareperfusion (I/R) injury in rats. Methods Thirty-two male Sprague-Dawley rats (six months, body weight between 250 g～300 g)were randomly divided into four groups (n=8): Sham group,I/R group, L group (lipid), Eto group (etomidate). Ischemia were induced by occluding the right middle cerebral artery in rat for 2 h. In I/R group, L group and Eto group, saline, lipid (the vehicle solution of etomidate )or etomidate(20 mg/kg)( the volume was fixed to 1 ml/100 g )were administered intraperitoneally immediately to rats at the onset of reperfusion respecetively. The neurological outcomes were evaluated after reperfusion 12,24 and 72 h by modified neurologic severity scores (NSS). The infarct size of brain was then assessed by 10 g/L 2,3,5-triphenyltetrazolium (TTC) staining following the last neurological outcome evaluation. Results The neurologic severity scores in Sham group was 0 at the three time points, and the neurologic severity scores in I/R group and L group at reperfusion 12,24 and 72 h were significantly more than those in Sham group (0)and Eto group (P＜0.05), there was no significant difference between I/R group and L group (P＞0.05 on 12, 24,72 h ). The infarct size of brain in I/R group(40.1±2.3 )% and L group (39.3±2.1)% were evidently greater than that in Sham group (0) and in Eto group (26.0±4.9)% (P＜0.05) at reperfusion 72 h, and there was no significant difference between I/R group and L group( P＞0.05 ). Conclusion Etomidate( 20 mg/kg ) has a brain protective effect on cerebral inschemia-reperfusion injury in rats. Key words: Etomidate; Postcoditioning; Cerebral ischemia-reperfusion; 2,3,5-triphenyltetrazolium

Ischemic postconditioning protects brain from ischemia/reperfusion injury by attenuating endoplasmic reticulum stress-induced apoptosis through PI3K-Akt pathway

Endoplasmic reticulum (ER) stress has been implicated in the pathology of cerebral ischemia. During prolonged period of stress or when the adaptive response fails, apoptotic cell death ensues. Cerebral ischemic postconditioning (Postcond) has been shown to reduce cerebral ischemia/reperfusion (I/R) injury in both focal and global cerebral ischemia model. However, the mechanism remains to be understood. This study aimed to elucidate whether Postcond attenuates brain I/R damage by suppressing ER stress-induced apoptosis and if the phosphatidylinositol-3kinase/Akt (PI3K/Akt) pathway is involved. A focal cerebral ischemia rat model was used in the study. Rat brain infarct size and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) positive cells in ischemic penumbra were assessed after reperfusion of the brain. The expressions of C/EBP-homologous protein (CHOP), caspase-12, glucose-regulated protein 78 (GRP78) and the phosphorylation of Akt (Ser473) in ischemic penumbra were measured after reperfusion. Our results showed that Postcond significantly attenuated brain I/R injury, as shown by reduction in infarct size, cell apoptosis, CHOP expression, caspase-12 activation and increase in GRP78 expression. LY294002, a phosphoinositide 3-kinase inhibitor, increased the number of TUNEL-positive cells suppressed by Postcond in penumbra. In addition, LY294002 diminished the effect of Postcond on the activation of CHOP, caspase-12 and GRP78. These results suggest that Postcond protects brain from I/R injury by suppressing ER stress-induced apoptosis and PI3K/Akt pathway is involved.

Erythropoietin Markedly Attenuates Brain Infarct Size and Improves Neurological Function in the Rat

BackgroundThe impact of epoetin beta (recombinant human erythropoietin) on brain infarction area (BIA) and neurological status in a rat model of acute ischemic stroke (IS) induced by distal left internal...

Rationale for a Nanomedicine Approach to Thrombolytic Therapy

Stroke is the third-leading cause of death and most common etiology for long-term adult disability. Of the approximate 700 000 individuals experiencing new or recurrent stroke annually, less than 5% of these individuals receive thrombolytic therapy.1–3 Intravenous recombinant tissue plasminogen activator (rt-PA) is an approved pharmacological treatment for acute ischemic stroke, but the window of opportunity is considered to be 3 hours from the onset of symptoms following a diagnostic imaging study to rule out hemorrhage. At the thrombolytic dosages approved, the incidence of intracranial hemorrhage in Europe and North America has been 6.4%.4 More recently, this time-window guideline has been liberalized to 3 to 6 hours, primarily because very few patients present for treatment within 3 hours.5 However, this change could bring a potential increase in the complication rate. The potential impact and value of a nanomedicine approach to this problem becomes apparent after examination of the alternatives that have been explored. Neuroprotective approaches to stroke treatment have generated considerable interest because of the low effective use rate of thrombolytic therapies and, if successful, would extend the therapeutic window. However, hundreds of compounds and thousands of articles have been written on neuroprotecting agents to be administered in the advent of a cerebral vascular accident, but none has achieved regulatory-approved status.6 The evidence from PET studies has revealed that early reperfusion, either spontaneous or chemically initiated, primarily determines the final size of brain infarction; these hypoperfused regions account for 70% of the final infarct volume. Reperfusion of the ischemic brain is the most effective therapy for acute stroke, restoring nutrition and oxygen-rich blood flow to threatened tissues. Endogenous enzymes such as rt-PA and urokinase control the conversion of plasminogen to plasmin and the ultimate digestion of fibrin. A number of circulating proteins neutralize plasmin; the best …

2-(-2-benzofuranyl)-2-imidazoline induces Bcl-2 expression and provides neuroprotection against transient cerebral ischemia in rats

Stroke is the third leading cause of death and disability in North America and is becoming the most frequent cause of death in the rapid developing China. Protecting neurons in order to minimize brain damage represents an effective approach towards stroke therapeutics. Our recent study demonstrated that 2-(-2-benzofuranyl)-2-imidazoline (2-BFI), a ligand for imidazoline I 2 receptors, is potently neuroprotective against stroke, possibly through transiently antagonizing NMDA receptor activities. In this study, we further investigated the characteristics and mechanisms of 2-BFI-mediated neuroprotection using a rat stroke model of transient occlusion of the middle cerebral artery. Here, we show that 2-BFI was most effective at the dose of 3 mg/kg in vivo, with significantly reduced brain infarct size and improved neurological deficits. Lower doses of 2-BFI at 1.5 mg/kg, or higher dose of 2-BFI at 6 mg/kg, were either not effective, or toxic to the brain, respectively. Treating stroke rats with 3 mg/kg 2-BFI significantly reduced the number of TUNEL positive cells and preserved the integrity of subcellular structures such as nuclear membranes and mitochondria as shown under the electron microscope, confirming neuroprotection. Most interestingly, 2-BFI-treated brains exhibited significant expression of Bcl-2, a gene with a known function in neuroprotection. Taken together, these studies not only demonstrated that 2-BFI at 3 mg/kg was effective in neuroprotection, but also, for the first time, showed that 2-BFI provided neuroprotection through up-regulating the neuroprotective gene Bcl-2. 2-BFI can be further developed as a therapeutic drug for stroke treatment.