莱菔硫烷对大鼠局灶性脑缺血再灌注损伤的保护作用及机制研究

目的 探讨莱菔硫烷对大鼠局灶性脑缺血再灌注损伤的保护作用及机制.方法 采用线栓法制备大鼠大脑中动脉阻断局灶性脑缺血模型,分别于MCAO后1h腹腔注射莱菔硫烷2.5mg/kg、5mg/kg、10mg/kg.于缺血2h再灌注24h时进行神经行为缺损评分,TTC染色评价脑梗死体积,测定脑组织中超氧化物歧化酶(SOD)活力和丙二醛(MDA)含量.免疫荧光组织化学染色法检测黄核蛋白NQ01和脂质过氧化酶Prx6的表达.结果 莱菔硫烷给药组与对照组相比均能改善大鼠脑缺血再灌注后神经行为缺损评分,减少脑梗死体积.其中5mg/kg组能显著改善大鼠脑缺血再灌注后神经行为缺损评分,减少脑梗死体积,增强SOD活性,降低MDA含量.免疫荧光组织化学染色法提示NQ01和Prx6的表达明显增强.结论 莱菔硫烷对大鼠局灶性脑缺血再灌注损伤有神经保护作用,其机制可能与上调内源性抗氧化蛋白NQ01和Prx6的表达有关.     

BMPER alleviates ischemic brain injury by protecting neurons and inhibiting neuroinflammation via Smad3‐Akt‐Nrf2 pathway

AimsBone morphogenetic proteins (BMPs) are a group of proteins related to bone morphogenesis. BMP‐binding endothelial regulator (BMPER), a secreted protein that interacts with BMPs, is known to be involved in ischemic injuries. Here, we explored the effects of BMPER on cerebral ischemia and its mechanism of action.MethodsA mouse model of brain ischemia was induced by middle cerebral artery occlusion (MCAO). An in vitro ischemic model was established by subjecting primary cultured neurons to oxygen‐glucose deprivation/reperfusion (OGD/R). Serum levels of BMPs/BMPER were measured in MCAO mice and in patients with acute ischemic stroke (AIS). Brain damages were compared between BMPER‐ and vehicle‐treated mice. Quantitative polymerase chain reaction (qPCR), immunohistochemistry, and immunofluorescence staining were performed to examine neuroinflammation and cell death. BMPER‐related pathways were assessed by Western blotting.ResultsBMPER level was elevated in MCAO mice and AIS patients. BMPER administration reduced mortality, infarct size, brain edema, and neurological deficit after MCAO. Neuroinflammation and cell death after ischemia were alleviated by BMPER both in vivo and in vitro. BMPER activated the Smad3/Akt/Nrf2 pathway in OGD/R‐challenged neurons.ConclusionBMPER is a neuroprotective hormone that alleviates ischemic brain injury via activating the Smad3/Akt/Nrf2 pathway. These findings may provide potential therapeutic strategies for stroke.     

Anemonin Alleviates Nerve Injury After Cerebral Ischemia and Reperfusion (I/R) in Rats by Improving Antioxidant Activities and Inhibiting Apoptosis Pathway

In the present study, we aimed at evaluating the potential neuroprotective effect and the underlying mechanism of anemonin against cerebral ischemia and reperfusion (I/R) injury. Anemonin was administered to rats by the intraperitoneally (i.p.) route once daily for 7 days before middle cerebral artery occlusion (MCAO). Focal cerebral ischemia was induced by 90 min of MCAO followed by 24 h of reperfusion. After that, animals were sacrificed by decapitation, brain was removed, and various biochemical estimations, neurological status, and assessment of cerebral infarct size were carried out. MCAO followed by 24 h of reperfusion caused a significant increase in infarct size, neurological deficit score, malondialdehyde (MDA) content, reactive oxygen species (ROS) level, and DNA fragmentation, as well as a decrease in the activities of superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH), glutathione peroxidase (GPx), and Na⁺, K⁺-ATPase in the brain. Furthermore, elevated Bax expression, increased caspase-3 cleavage, and decreased Bcl-2 expression were observed in nontreated rats in response to focal cerebral I/R injury. However, pretreatment with anemonin significantly reversed these levels of biochemical parameters, reduced cerebral infarct size, and improved the neurologic score in cerebral ischemic animals. Additionally, a wide distribution of anemonin in plasma and brain tissues and the brain-to-plasma partition coefficient (Ri) ratio of 0.7 at 90 min indicated that this compound could penetrate the blood-brain barrier (BBB). These results showed that pretreatment with anemonin provided a significant protection against cerebral I/R injury in rats by, at least in part, its antioxidant action and consequent inhibition of apoptosis.     

Tenascin-C preserves microglia surveillance and restricts leukocyte and,more specifically,T cell infiltration of the ischemic brain

As an endogenous activator of toll-like receptor-4 (Tlr4), the extracellular matrix glycoprotein tenascin-C (TnC) regulates chemotaxis, phagocytosis and proinflammatory cytokine production in microglia. The role of TnC for ischemic brain injury, post-ischemic immune responses and stroke recovery has still not been evaluated. By comparing wild type and TnC^−/− mice exposed to transient intraluminal middle cerebral artery occlusion (MCAO), we examined the effects of TnC deficiency for ischemic injury, neurological deficits, microglia/macrophage activation and brain leukocyte infiltration using behavioural tests, histochemical studies, Western blot, polymerase chain reaction and flow cytometry. Histochemical studies revealed that TnC was de novo expressed in the ischemic striatum, which contained the infarct core, and overlapped with the area of strongest accumulation of Iba1 + microglia/macrophages. TnC deficiency increased overall Iba1 immunoreactivity in the perilesional cortex, suggesting that TnC might restrict the distribution of microglial cells to the infarct core. By analysing microglial morphology in 3D we found that the post-ischemic loss of microglial cell territory, branching and volume at 3 and 7 days post-ischemia was amplified in the brains of TnC deficient compared with wild type mice. Microglial cell number was not different between genotypes. Hence, TnC deficiency reduced tissue surveillance by microglial cells. Concomitantly, the number of infiltrating leukocytes and, more specifically, T cells was increased in the ischemic brain parenchyma of TnC deficient compared with wild type mice. Ischemic injury and neurological deficits were not affected by TnC deficiency. We propose that the reduced microglia surveillance in TnC deficient mice might favour leukocyte accumulation in the ischemic brain.     

Atorvastatin Pretreatment Attenuates Ischemic Brain Edema by Suppressing Aquaporin 4

Background: Cerebral edema, a serious complication of acute cerebral infarction, has a crucial impact on morbidity and mortality in the early stage of cerebral infarction. And aquaporin 4 (AQP4), a bidirectional water transporting protein, plays a pivotal role in edema formation. At experimental model, it has proven that atorvastatin could exert pleiotropic neuroprotection on acute cerebral infarction independent of its cholesterol-lowering action. It was a common protective manifestation that atorvastatin can reduce the infarct volume and cerebral edema. However, little is known about atorvastatin improving ischemic brain edema by regulating AQP4 expression. This study intended to investigate the neuroprotection effects of atorvastatin pretreatment in rats with cerebral ischemia and further explore the potential relationship between atorvastatin and AQP4 expression. Methods: Fifty-one adult male Sprague Dawley rats were randomly divided into 3 groups: sham, middle cerebral artery occlusion (MCAO), and atorvastatin pretreatment (Ator) group. For Ator group, 20 mg/kg of atorvastatin injectable suspension was administered once for 7days by gavage before operation, whereas the others were administered the same volume of saline matching. Except for sham group, MCAO and Ator groups were subjected to permanent MCAO by modified intraluminal suture method. Infarct volume, neurological deficit, brain water content (BWC), immunohistochemistry, western blot, and polymerase chain reaction (PCR) were measured at 24 hours after MCAO. Results: Compared with sham group, the mNSS, infarct volume, and BWC of ischemic hemisphere were significantly increased (P < 0.001) in MCAO group. Positive cells and protein levels of p-p38MAPK and AQP4 in peri-infarction were significantly increased (P < 0.01). The mRNA levels of p38MAPK and AQP4 were also prominently upregulated (P < 0.01). Interestingly, preadministration of atorvastatin dramatically decreased infarct volume and the BWC of ischemic hemisphere compared with MCAO group (P < 0.05). The overexpressions of p-p38MAPK and AQP4 in peri-infarction were significantly decreased (P < 0.05) and their mRNA levels were downregulated by atorvastatin pretreatment (P < 0.05). Neurological deficits were also dramatically improved (P < 0.001). Conclusion: To the best of our knowledge, this is the first study that demonstrates an effect of atorvastatin on expression of AQP4, and we propose that decreased AQP4 expression through a p38MAPK-suppression pathway may be the mechanism of atorvastatin alleviating ischemic cerebral edema.     

Cerebroprotective action of a Na/Ca channel blocker NS-7: I. Effect on the cerebral infarction and edema at the acute stage of permanent middle cerebral artery occlusion in rats

The effect of a novel Na⁺/Ca²⁺ channel blocker NS-7 [4-(4-fluorophenyl)-2-methyl-6-(5-piperidinopentyloxy)pyrimidine hydrochloride] on the cerebral infarction, edema and brain energy metabolism was investigated in rats after permanent middle cerebral artery occlusion (MCAO). The infarction and brain water content were evaluated at 48 h and 24 h after MCAO, respectively. A single bolus injection of NS-7 (0.03125–0.25 mg/kg) immediately after MCAO produced a dose-dependent reduction in the infarct volume as well as edema both in the cerebral cortex and striatum. Glycerol (4 g/kg) also decreased water content both in the occluded and non-occluded brain, but it did not reduce the size of cerebral infarction. Unlike glycerol, NS-7 did not change the water content in non-occluded brain. Moreover, a significant protective action was still observed even when NS-7 was injected once at 12 h after occlusion. In addition, NS-7 significantly reversed the decrease in tissue ATP content observed at 3 h but not at 0.5 h after MCAO. These findings suggest that a Na⁺/Ca²⁺ channel blocker NS-7 protects cerebral tissues against ischemic insults by improving the disturbance of cerebral energy metabolism and suppressing the cerebral edema.     

Apelin-13 Protects the Brain Against Ischemic Reperfusion Injury and Cerebral Edema in a Transient Model of Focal Cerebral Ischemia

The adipocytokine apelin is a peptide that was isolated from a bovine stomach for the first time. This peptide and its receptor are abundantly expressed in the nervous and cardiovascular systems. According to previous studies, apelin-13 protects cardiomyocytes from ischemic injury as well as apoptosis. In addition, this peptide has a neuroprotective effect on hippocampal and cultured mouse cortical neurons against NMDA receptor-mediated excitotoxicity. The present study was conducted to determine whether apelin-13 provides protection in transient focal cerebral ischemia. Focal ischemia was induced by 60-min middle cerebral artery occlusion (MCAO), followed by 23-h reperfusion. Saline as a vehicle and apelin-13 at doses of 25, 50, and 100 μg were injected intracerebroventriculary (ICV) at the beginning of ischemia. Infarct volume ,brain edema, motor dysfunction, and apoptosis were assessed 24 h after MCAO. Treatment with apelin-13 at doses of 50 and 100 μg ICV markedly reduced total infarct volumes by 45 and 55 %, respectively (P?P?>?0.05). In addition, apelin-13 at doses of 50 and 100 μg reduced brain edema (P?P?P?>?0.05).     

两种线栓法制作小鼠大脑中动脉栓塞模型的比较

目的通过颈总动脉和颈外动脉两种栓塞途径插入线栓在小鼠身上建立短暂性大脑中动脉栓塞（MCAO）模型，比较分析两种模型实验动物的术后存活率、行为学、梗死体积、脑水肿程度以及神经细胞凋亡情况，从而筛选出更为可行有效的脑梗死模型建立方法。 方法42只C57BL/6雄性小鼠，体质量20~22 g，按照随机数字表法分为假手术组（6只）、MCAO模型颈外动脉插线组（18只，颈外组）、MCAO模型颈总动脉插线组（18只，颈总组）。颈外组从颈外动脉剪口插入线栓栓塞大脑中动脉起始部制备小鼠大脑中动脉栓塞模型，颈总组从颈总动脉剪口插入线栓栓塞大脑中动脉起始部制备小鼠大脑中动脉栓塞模型，假手术组结扎与模型组同侧颈总动脉相同，但不插入线栓。颈外组和颈总组缺血1 h、假手术组颈总动脉结扎1 h，其后拔出线栓解除结扎，同时再灌注24 h，其后采用Longa神经功能评分，灌流取脑TTC染色，计算梗死体积并测出脑组织含水量，观察神经细胞凋亡情况，从而进行比较分析。 结果颈外组和颈总组小鼠均出现脑卒中表现、神经功能评分升高、出现脑水肿、有明显梗死体积以及神经细胞凋亡，假手术组未出现与之相对的明显表征。颈总组与颈外组相比，梗死体积和脑水肿程度接近，神经细胞凋亡数量基本一致，差异无统计学意义（P>0.05）；颈总组相对颈外组，神经功能评分较高，死亡率较高，差异具有统计学意义（P<0.05）。 结论两种栓塞途径所造成的脑梗死比较结果一致，但考虑到部分实验需要长期给药观察，颈外动脉栓塞途径实验动物存活率更高，所以推荐采用颈外动脉插线方法制作大脑中动脉栓塞模型。     

PGF2α FP Receptor Contributes to Brain Damage Following Transient Focal Brain Ischemia

Although some of the COX-2 metabolites and prostaglandins have been implicated in stroke and excitotoxicity, the role of prostaglandin F_2α (PGF_2α) and its FP receptor have not been elucidated in the pathogenesis of ischemic-reperfusion (I/R) brain injury. Here we investigated the FP receptor’s contribution in a unilateral middle cerebral artery (MCA) occlusion model of focal cerebral ischemia in mice. The MCA in wild type (WT) and FP knockout (FP^?/?) C57BL/6 male mice was transiently occluded with a monofilament for 90 min. After 96 h of reperfusion, the FP^?/? mice had 25.3% less neurological deficit (P < 0.05) and 34.4% smaller infarct volumes (P < 0.05) than those of the WT mice. In a separate cohort, physiological parameters were monitored before, during, and after ischemia, and the results revealed no differences between the groups. Because excitotoxicity is an acute mediator of stroke outcome, the effect of acute NMDA-induced neurotoxicity was also tested. Forty-eight hours after unilateral intrastriatal NMDA injection, excitotoxic brain damage was 20.8% less extensive in the FP^?/? mice (P < 0.05) than in the WT counterparts, further supporting the toxic contribution of the FP receptor in I/R injury. Additionally, we investigated the effect of post-treatment with the FP agonist latanoprost in mice subjected to MCA occlusion; such treatment resulted in an increase in neurological deficit and infarct size in WT mice (P < 0.05), though no effects were observed in the latanoprost-treated FP^?/? mice. Together, the results suggest that the PGF_2α FP receptor significantly enhances cerebral ischemic and excitotoxic brain injury and that these results are of importance when planning for potential development of therapeutic drugs to treat stroke and its acute and/or long term consequences.     

<Emphasis Type="Italic">N</Emphasis>-Acetylcysteine and Ceftriaxone as Preconditioning Strategies in Focal Brain Ischemia: Influence on Glutamate Transporters Expression

Glutamate (Glu) plays a key role in excitotoxicity-related injury in cerebral ischemia. In the brain, Glu homeostasis depends on Glu transporters, including the excitatory amino acid transporters and the cysteine/Glu antiporter (xc-). We hypothesized that drugs acting on Glu transporters, such as ceftriaxone (CEF, 200 mg/kg, i.p.) and N-acetylcysteine (NAC, 150 mg/kg, i.p.), administered repeatedly for 5 days before focal cerebral ischemia in rats and induced by a 90-min middle cerebral artery occlusion (MCAO), may induce brain tolerance to ischemia. We compared the effects of these drugs on brain infarct volume, neurological deficits and the mRNA and protein expression of the Glu transporter-1 (GLT-1) and xc- with the effects of ischemic preconditioning and chemical preconditioning using 3-nitropropionic acid. Administration of CEF and NAC significantly reduced infarct size and neurological deficits caused by a 90-min MCAO. These beneficial effects were accompanied by changes in GLT-1 expression caused by a 90-min MCAO at both the mRNA and protein levels in the frontal cortex, hippocampus, and dorsal striatum. Thus, the results of this study suggest that the regulation of GLT-1 and xc- plays a role in the development of cerebral tolerance to ischemia and that this regulation may be a novel approach in the therapy of brain ischemia.     

脑缺血预处理及HSP70表达对大鼠脑梗死的保护作用

目的建立局灶性可重复性大鼠脑缺血动物模型,探讨蛋白合成在脑缺血预处理(PC)诱导脑缺血耐受(IT)中的作用。方法应用改进的Longa’s法建立局灶脑缺血(MCAO)模型,短暂性脑缺血20min作为PC,PC 后24h给予永久性MCAO(PMCAO),并与未进行PC者比较。免疫印记法测量PC后24h及给予蛋白合成抑制剂放线菌酮后HSP70的变化,PMCAO24h后观察脑梗死的大小,神经功能评分;同时观察在PC前或PC后PMCAO 前给予蛋白合成抑制剂放线菌酮对上述指标的影响。结果 PC后24h行PMCAO,脑梗死体积明显减小(P<0．01), 神经功能评分减低(P<0．05);PC前给予放线菌酮消除了以上影响,但在PC后较长时间而在PMCAO之前给予则没有以上影响;HSP70在PC后24h明显表达,而在PC前30min给予防线菌酮抑制了HSP70的表达。结论 PC能够通过减少脑组织损伤和神经功能缺损对之后发生的脑缺血产生脑保护作用。PC诱导脑缺血耐受有赖于新蛋白的合成。     

Progesterone is neuroprotective after transient middle cerebral artery occlusion in male rats

Progesterone (PROG) is a neurosteroid, possessing a variety of functions in the central nervous system. Exogenous PROG has been shown to reduce secondary neuronal loss in conjunction with attenuated brain edema after cerebral contusion and to reduce brain edema after focal cerebral ischemia. In the present study, we assessed the neuroprotective potential of PROG in a model of focal cerebral ischemia in the rat. Forty-eight male Wistar rats were randomly assigned to 4 groups, i.e. pretreatment with water soluble PROG, or dimethyl sulfoxide (DMSO) dissolved PROG, or DMSO as control or delayed treatment with DMSO dissolved PROG. Middle cerebral artery occlusion (MCAO) was induced by insertion of an intraluminal suture and reperfusion was performed by withdrawing the suture. Pretreatments were initiated 30 min before MCAO via intraperitoneal injection. Delayed treatment was initiated upon reperfusion following 2 h of MCAO. Infarct volume, body weight loss, and neurological deficit were measured 48 h after MCAO. Pre- and delayed treatment with DMSO dissolved PROG resulted in a 39% (P < 0.05) and 34% (P < 0.05) reduction in cerebral infarction, respectively, along with decreased body weight loss and improved neurological function as compared to control animals, whereas no statistically significant reduction in infarct volume by water soluble PROG was found. We demonstrated that administration of PROG to the male rat before or 2 hours after onset of MCAO reduces ischemic cell damage and improves physiological and neurological function 2 days after stroke. These results suggests potential therapeutic properties of PROG in the management of stroke.     

Gene therapy and neuroprotection for cerebral infarction]

Topical application of GDNF protein greatly reduced the infarct size and brain edema at 24 hr of continuous MCAO in rats. The reduction of the infarct size was not related to a change of cerebral blood flow (CBF), but was accompanied by marked reduction of positive cells for TUNEL and caspases in the affected area. GDNF protein showed a direct protective effect against ischemic brain damage, but not secondary by improving CBF. Pretreatment of animals with Ad-GDNF 24 hr before the subsequent 90 min of transient MCAO effectively reduced infract volume and area without affecting regional CBF compared to the vehicle or Ad-LacZ animal groups. Free radical scavenger edaravone effectively reduced brain edema, infarct size, and peroxidative markers of protein, lipid and DNA. Thus, gene therapy and neuroprotective strategy have a great potential for reducing ischemic brain damage of human stroke patients in the near future.     

S-Nitrosoglutathione Mimics the Beneficial Activity of Endothelial Nitric Oxide Synthase-Derived Nitric Oxide in a Mouse Model of Stroke

Background: The nitric oxide (NO)-producing activity of endothelial nitric oxide synthase (eNOS) plays a significant role in maintaining endothelial function and protecting against the stroke injury. However, the activity of the eNOS enzyme and the metabolism of major NO metabolite S-nitrosoglutathione (GSNO) are dysregulated after stroke, causing endothelial dysfunction. We investigated whether an administration of exogenous of GSNO or enhancing the level of endogenous GSNO protects against neurovascular injury in wild-type (WT) and eNOS-null (endothelial dysfunction) mouse models of cerebral ischemia-reperfusion (IR). Methods: Transient cerebral ischemic injury was induced by middle cerebral artery occlusion (MCAO) for 60 minutes in male adult WT and eNOS null mice. GSNO (0.1 mg/kg body weight, intravenously) or N6022 (GSNO reductase inhibitor, 5.0 mg/kg body weight, intravenously) was administered 30 minutes before MCAO in preinjury and at the reperfusion in postinjury studies. Brain infarctions, edema, and neurobehavioral functions were evaluated at 24 hours after the reperfusion. Results: eNOS-null mice had a higher degree (P< .05) of injury than WT. Pre- or postinjury treatment with either GSNO or N6022 significantly reduced infarct volume, improved neurological and sensorimotor function in both WT and eNOS-null mice. Conclusion: Reduced brain infarctions and edema, and improved neurobehavioral functions by pre- or postinjury GSNO treatment of eNOS knock out mice indicate that GSNO can attenuate IR injury, likely by mimicking the eNOS-derived NO-dependent anti-ischemic and anti-inflammatory functions. Neurovascular protection by GSNO/N6022 in both pre- and postischemic injury groups support GSNO as a promising drug candidate for the prevention and treatment of stroke injury.     

Reduction of ischemic brain injury by anti-P-selectin monoclonal antibody after permanent middle cerebral artery occlusion in rat

Abstract

The selectin family of adhesion molecules is involved in adhesion of leukocyte to microcirculatory system and the transmigration into brain parenchyma. Although the role of P-selectin may be important in the pathogenesis of brain ischemia, a possible protective effect on ischemic brain injury by blocking P-selectin has not been reported. We have examined the effects of a novel anti-P-selectin antibody on ischemic brain injury after 24 h of permanent middle cerebral artery occlusion (MCAO) in rat. Male Wistar rats were subjected to MCAO by an insertion of a silicone rubber cylinder for 24 h. Anti-rat P-selectin monoclonal antibody, ARP 2-4 was injected intravenously at a dose of 1 mg kg^–1 at 5 min before the induction of MCAO. Control animals received the same volume of vehicle solution. Regional cerebral blood flow (rCBF) was measured immediately after and at 8 h of MCAO. At decapitation of rats at 24 h of permanent MCAO, infarct size was compared between the antibody and vehicle treated group. In addition, immunohisto- chemistry for leukocyte infiltration and HSP72, and histochemistry for TUNEL were also compared. Pretreatment with ARP 2-4 improved rCBF at 8 h of MCAO (55.4% ± 11.7% of control, n = 5) as compared to vehicle group (24.2% ± 77.8%, n = 5, p < 0.02). Although leukocyte infiltration was not normally detected by monoclonal antibodies for CD11a and CD18, it became remarkably evident at 7 day of MCAO. Although HSP72 and TUNEL were not also detected in sham control brains, they were induced in neurons of the MCA area at 7 day of MCAO. Treatment with ARP 2-4 significantly reduced the numbers of leukocyte and neurons with positive HSP72 and TUNEL stainings. These results demonstrated that an administration of a monoclonal antibody against P-selectin improved rCBF, and attenuated infarct size that was associated with reduction of leukocyte infiltration. Furthermore, treatment with the antibody reduced both HSP72 and TUNEL stainings. These data suggest an important role of P-selectin in ischemic brain damage, and a future therapeutic potential to human stroke patients. [Neurol Res 1999; 21: 269-276]     

Ocimum sanctum attenuates oxidative damage and neurological deficits following focal cerebral ischemia/reperfusion injury in rats

Stroke is an enormous public health problem with an imperative need for more effective therapy. Free radicals have been reported to play a role in the expansion of ischemic brain lesions, and the effect of free radical scavengers is still under debate. The present study investigated the neuroprotective effect of Ocimum sanctum (OS) to reduce brain injury after middle cerebral artery occlusion (MCAO). Male Wistar rats were subjected to MCAO for 2?h and reperfused for 22?h. The administration of OS (200?mg/kg bwt., orally) once daily for 15?days before MCAO showed marked reduction in infarct size, reduced the neurological deficits, and suppressed neuronal loss in MCAO rats. A significantly depleted activity of antioxidant enzymes and content of glutathione in MCAO group were protected significantly in MCAO group pretreated with OS. Conversely, the elevated level of thiobarbituric acid-reactive substances (TBARS) in MCAO group was attenuated significantly in OS-pretreated group when compared with MCAO group. Consequently, OS pretreatment may reduce the deterioration caused by free radicals, and thus may used to prevent subsequent behavioral, biochemical and histopathological changes that transpire during cerebral ischemia. This finding reflects that supplementation of OS intuitively by reasonable and understandable treatment effectively ameliorates the cerebral ischemia-induced oxidative damage.     

Obstructive sleep apnea intensifies stroke severity following middle cerebral artery occlusion

Study objectivesObstructive sleep apnea (OSA) is a sleep disorder caused by transient obstruction of the upper airway and results in intermittent hypoxia, sleep fragmentation, sympathetic nervous system activation, and arousal which can have an adverse effect on cardiovascular disease. It is theorized that OSA might intensify stroke injury. Our goal here was to develop a new model of experimental OSA and test its ability to aggravate behavioral and morphological outcomes following transient brain ischemia/reperfusion.MethodsWe used a 3D printed OSA device to expose C57BL6 mice to 3 h of OSA (obstructive apnea index of 20 events per hour) for three days. These mice were then subjected to ischemia/reperfusion using the middle cerebral artery occlusion model (MCAO) stroke and examined for overall survival, infarct size and neurological scoring.ResultsWe found that OSA transiently decreased respiration and reduced oxygen saturation with bradycardia and tachycardia typical of human responses during apneic events. Brain injury from MCAO was significantly increased by OSA as measured by infarct size and location as well as by intensification of neurological deficits; mortality following MCAO was also increased in OSA animals.ConclusionsOur findings suggest that our new model of OSA alters respiratory and cardiovascular physiological functions and is associated with enhanced ischemia/reperfusion mediated injury in our non-invasive, OSA intensified model of stroke.     

Platelet endothelial cell adhesion molecule-1 is a gatekeeper of neutrophil transendothelial migration in ischemic stroke

RationaleAdhesion molecules are key elements in stroke-induced brain injury by regulating the migration of effector immune cells from the circulation to the lesion site. Platelet endothelial cell adhesion molecule-1 (PECAM-1) is an adhesion molecule highly expressed on endothelial cells and leukocytes, which controls the final steps of trans-endothelial migration. A functional role for PECAM-1 in post-ischemic brain injury has not yet been demonstrated.ObjectiveUsing genetic Pecam-1 depletion and PECAM-1 blockade using a neutralizing anti-PECAM-1 antibody, we evaluated the role of PECAM-1 mediated trans-endothelial immune cell migration for ischemic injury, delayed brain atrophy, and brain immune cell infiltrates. Trans-endothelial immune cell migration was furthermore evaluated in cultured human cerebral microvascular endothelial cells.Methods and resultsTransient middle cerebral artery occlusion (tMCAO) was induced in 10–12-week-old male Pecam-1^−/− and Pecam-1^+/+ wildtype mice. PECAM-1 levels increased in the ischemic brain tissue due to the infiltration of PECAM-1⁺ leukocytes. Using magnetic resonance imaging, we observed smaller infarct volume, less edema formation, and less brain atrophy in Pecam-1^−/− compared with Pecam-1^+/+ wildtype mice. The transmigration of leukocytes, specifical neutrophils, was selectively reduced by Pecam-1^−/−, as shown by immune fluorescence and flow cytometry in vivo and transmigration assays in vitro. Importantly, inhibition with an anti-PECAM-1 antibody in wildtype mice decreased neutrophil brain influx and infarct.ConclusionPECAM-1 controls the trans-endothelial migration of neutrophils in a mouse model of ischemic stroke. Antibody blockade of PECAM-1 after stroke onset ameliorates stroke severity in mice, making PECAM-1 an interesting target to dampen post-stroke neuroinflammation, reduce ischemic brain injury, and enhance post-ischemic brain remodeling.     

Increased oligodendrogenesis by humanin promotes axonal remyelination and neurological recovery in hypoxic/ischemic brains

Oligodendrocytes are the predominant cell type in white matter and are highly vulnerable to ischemic injury. The role of oligodendrocyte dysfunction in ischemic brain injury is unknown. In this study, we used a 24‐amino acid peptide S14G‐Humanin (HNG) to examine oligodendrogenesis and neurological functional recovery in a hypoxic/ischemic (H/I) neonatal model. Intraperitoneal HNG pre‐treatment decreased infarct volume following H/I injury. Delayed HNG treatment 24 h after H/I injury did not reduce infarct volume but did decrease neurological deficits and brain atrophy. Delayed HNG treatment did not attenuate axonal demyelination at 48 h after H/I injury. However, at 14 d after H/I injury, delayed HNG treatment increased axonal remyelination, the thickness of corpus callosum at the midline, the number of Olig2⁺/BrdU⁺ cells, and levels of brain‐derived neurotrophic factor (BDNF). Our results suggest that targeting oligodendrogenesis via delayed HNG treatment may represent a promising approach for the treatment of stroke. © 2014 Wiley Periodicals, Inc.