Peroxisome proliferator-activated receptor-gamma-agonist, rosiglitazone, promotes angiogenesis after focal cerebral ischemia

Peroxisome proliferator-activated receptor-gamma (PPAR-gamma) agonist, rosiglitazone, not only improves insulin resistance in patients with type II diabetes but also exerts a broad spectrum protective effects in variable animal models of neurologic or cardiovascular diseases. We studied the effect of rosiglitazone on angiogenesis and neurological recovery after focal cerebral ischemia. Rosiglitazone (3 mg/kg or 0.3 mg/kg, p.o.) was administered for 7 days prior to and 3 days after the induction of focal ischemia (total 10 days) in adult rats. The rosiglitazone-treated group showed the enhanced neurologic improvement, the reduced infarction volume compared to the ischemia-vehicle group with dose dependency, and the reduced hemispheric atrophy. Rosiglitazone treatment reduced TUNEL(+)/activated caspase-3(+) cells, MPO(+)/Ox-42(+) inflammatory cell infiltrations, caspase-3 activity, and Bax(+) cells, as compared to the ischemia-vehicle group. The vascular surface area, the vascular branch points, the vascular length, and the number of BrdU(+) endothelial cells were significantly increased in the rosiglitazone group compared with the ischemia-vehicle group. Rosiglitazone increased eNOS expression around the ischemic margin with downregulation of FasL. Here, we show that rosiglitazone treatment enhances angiogenesis and functional recovery with dose-dependent induction of ischemic tolerance.     

Constraint-induced movement therapy enhances angiogenesis and neurogenesis after cerebral ischemia/reperfusion

Constraint-induced movement therapy after cerebral ischemia stimulates axonal growth by decreasing expression levels of Nogo-A,RhoA,and Rho-associated kinase(ROCK)in the ischemic boundary zone.However,it remains unclear if there are any associations between the Nogo-A/RhoA/ROCK pathway and angiogenesis in adult rat brains in pathological processes such as ischemic stroke.In addition,it has not yet been reported whether constraint-induced movement therapy can promote angiogenesis in stroke in adult rats by overcoming Nogo-A/RhoA/ROCK signaling.Here,a stroke model was established by middle cerebral artery occlusion and reperfusion.Seven days after stroke,the following treatments were initiated and continued for 3 weeks:forced limb use in constraint-induced movement therapy rats(constraint-induced movement therapy group),intraperitoneal infusion of fasudil(a ROCK inhibitor)in fasudil rats(fasudil group),or lateral ventricular injection of NEP1-40(a specific antagonist of the Nogo-66 receptor)in NEP1-40 rats(NEP1-40 group).Immunohistochemistry and western blot assay results showed that,at 2 weeks after middle cerebral artery occlusion,expression levels of RhoA and ROCK were lower in the ischemic boundary zone in rats treated with NEP1-40 compared with rats treated with ischemia/reperfusion or constraint-induced movement therapy alone.However,at 4 weeks after middle cerebral artery occlusion,expression levels of RhoA and ROCK in the ischemic boundary zone were markedly decreased in the NEP1-40 and constraint-induced movement therapy groups,but there was no difference between these two groups.Compared with the ischemia/reperfusion group,modified neurological severity scores and foot fault scores were lower and time taken to locate the platform was shorter in the constraint-induced movement therapy and fasudil groups at 4 weeks after middle cerebral artery occlusion,especially in the constraint-induced movement therapy group.Immunofluorescent staining demonstrated that fasudil promoted an immune response of nerve-regeneration-related markers(BrdU in combination with CD31(platelet endothelial cell adhesion molecule),Nestin,doublecortin,NeuN,and glial fibrillary acidic protein)in the subventricular zone and ischemic boundary zone ipsilateral to the infarct.After 3 weeks of constraint-induced movement therapy,the number of regenerated nerve cells was noticeably increased,and was accompanied by an increased immune response of tight junctions(claudin-5),a pericyte marker(a-smooth muscle actin),and vascular endothelial growth factor receptor 2.Taken together,the results demonstrate that,compared with fasudil,constraint-induced movement therapy led to stronger angiogenesis and nerve regeneration ability and better nerve functional recovery at 4 weeks after cerebral ischemia/reperfusion.In addition,constraint-induced movement therapy has the same degree of inhibition of RhoA and ROCK as NEP1-40.Therefore,constraint-induced movement therapy promotes angiogenesis and neurogenesis after cerebral ischemia/reperfusion injury,at least in part by overcoming the Nogo-A/RhoA/ROCK signaling pathway.All protocols were approved by the Institutional Animal Care and Use Committee of China Medical University,China on December 9,2015(approval No.2015 PS326 K).     

Nuclear translocation of apoptosis-inducing factor after focal cerebral ischemia.

Signaling cascades associated with apoptosis contribute to cell death after focal cerebral ischemia. Cytochrome c release from mitochondria and the subsequent activation of caspases 9 and 3 are critical steps. Recently, a novel mitochondrial protein, apoptosis-inducing factor (AIF), has been implicated in caspase-independent programmed cell death following its translocation to the nucleus. We, therefore, addressed the question whether AIF also plays a role in cell death after focal cerebral ischemia. We detected AIF relocation from mitochondria to nucleus in primary cultured rat neurons 4 and 8 hours after 4 hours of oxygen/glucose deprivation. In ischemic mouse brain, AIF was detected within the nucleus 1 hour after reperfusion after 45 minutes occlusion of the middle cerebral artery. AIF translocation preceded cell death, occurred before or at the time when cytochrome c was released from mitochondria, and was evident within cells showing apoptosis-related DNA fragmentation. From these findings, we infer that AIF may be involved in neuronal cell death after focal cerebral ischemia and that caspase-independent signaling pathways downstream of mitochondria may play a role in apoptotic-like cell death after experimental stroke.     

粒细胞集落刺激因子与血液病

摘要：粒细胞集落刺激因子是一种糖基化的多肽链细胞生长因子,能特异地调节粒系祖细胞的增殖与分化,并能增强成熟中性粒细胞的功能。粒细胞集落刺激因子功能的发挥有赖于与效应细胞表面的特异性受体的结合。随着基因克隆技术的发展,粒细胞集落刺激因子重组产品已广泛应用于临床,为血液系统疾病的治疗提供了有力手段。目前在临床上广泛用于白细胞减少性疾病。近年来在化疗基础上联用粒细胞集落刺激因子的预激方案也取得良好疗效,为难治、复发、老年急性髓系白血病的治疗创造了机会。目前,粒细胞集落刺激因子是临床上应用最成功的几种造血调控因子之一。     

Glibenclamide enhances neurogenesis and improves long-term functional recovery after transient focal cerebral ischemia

Glibenclamide is neuroprotective against cerebral ischemia in rats. We studied whether glibenclamide enhances long-term brain repair and improves behavioral recovery after stroke. Adult male Wistar rats were subjected to transient middle cerebral artery occlusion (MCAO) for 90 minutes. A low dose of glibenclamide (total 0.6 μg) was administered intravenously 6, 12, and 24 hours after reperfusion. We assessed behavioral outcome during a 30-day follow-up and animals were perfused for histological evaluation. In vitro specific binding of glibenclamide to microglia increased after pro-inflammatory stimuli. In vivo glibenclamide was associated with increased migration of doublecortin-positive cells in the striatum toward the ischemic lesion 72 hours after MCAO, and reactive microglia expressed sulfonylurea receptor 1 (SUR1) and Kir6.2 in the medial striatum. One month after MCAO, glibenclamide was also associated with increased number of NeuN-positive and 5-bromo-2-deoxyuridine-positive neurons in the cortex and hippocampus, and enhanced angiogenesis in the hippocampus. Consequently, glibenclamide-treated MCAO rats showed improved performance in the limb-placing test on postoperative days 22 to 29, and in the cylinder and water-maze test on postoperative day 29. Therefore, acute blockade of SUR1 by glibenclamide enhanced long-term brain repair in MCAO rats, which was associated with improved behavioral outcome.     

Hyperthermia enhances spectrin breakdown in transient focal cerebral ischemia

Calpain-mediated spectrin degradation is triggered by cerebral ischemia and, when persistent, is thought to signal irreversible neuronal injury. Hyperthermia superimposed upon cerebral ischemia may exacerbate the injury process. In this study, we compared the extent of spectrin degradation in the brains of rats subjected to 1 h of transient proximal middle cerebral artery (MCA) clip-occlusion performed under conditions of cranial normothermia (37°C) or mild cranial hyperthermia (39°C). Immunocytochemical localization of spectrin breakdown products was achieved by the use of a rabbit polyclonal antibody which reacted selectively with calpain-generated fragments of brain spectrin. The perfusion times studied were 1, 4 or 24 h. Following normothermic MCA occlusion, spectrin immunoreactivity was present only occasionally and only in scattered cortical neurons immediately upon reperfusion and 1 h later; all normothermic brains showed sparse immunoreactivity at 4 h of reperfusion; and no immunoreactivity was detected at 24 h. By contrast, following hyperthermic MCA occlusion, moderate-to-intense immunostaining was present in cortical pyramidal neurons even immediately upon reperfusion and persisted at 1 h of reperfusion. At 4 and 24 h, most brains exhibited dense immunoreactivity associated with morphologically shrunken neurons. Following 24 h survival, semi-thick plastic sections revealed intact neuropil and only selective neuronal necrosis in normothermic rats. By contrast, pan-necrosis was evident 24 h after the hyperthermic ischemic insult. These results indicate that mild cranial hyperthermia superimposed upon transient focal ischemia markedly enhances calpain activation and spectrin degradation; this process appears to be an important mechanism by which hyperthermia exacerbates ischemic injury.     

Vascular endothelial growth factor induced angiogenesis following focal cerebral ischemia/reperfusion injury in rabbits

INTRODUCTIONAt present, ischemic cerebrovascular diseases are mainly treated bythrombolysis, anticoagulation and anti-platelet aggregation, which arethe traditional methods for prevention and treatment of thrombosisand vasodilatation, to ameliorate blood …     

局灶缺血诱导大鼠脑肝细胞生长因子表达的动态观察

目的:探讨肝细胞生长因子(HGF)在局灶脑缺血边缘区表达的动态变化及其意义。方法:采取线栓法建立局灶脑缺血模型,根据缺血时间分为1h、3h、12h、24h组,RT-PCR法检测HGF的表达及其动态变化。结果:缺血1h脑缺血边缘区即有HGF的表达,且随着缺血时间的延长其表达逐渐增强,24h尤为明显。结论:HGF在局灶脑缺血诱导的高表达可能在脑缺血损伤组织的保护及修复过程中起重要作用。     

Specific cardiological evaluation after focal cerebral ischemia

Purpose of this study was to define a subgroup of TIA/stroke patients who should be examined by transthoracal and transesophageal echocardiography or Holter-electrocardiography to identify those with cardiogenic brain embolism reliably; 300 consecutive patients with acute focal brain ischemia underwent a standardized diagnostic protocol for the evaluation of the etiology including, clinical examination by a cardiologist and routine electrocardiography, Holter-electrocardiography, transthoracal and transesophageal echocardiography. 188 patients had a potential cardiac source of embolism. In particular echocardiography was diagnostic in 163 patients, and Holter-electrocardiography 10; 159 of these 188 patients (84.6%) had competitive etiologies, predominantly large vessel atherosclerosis. In 136 patients cardiogenic brain embolism was assumed as quite definite or possible. To identify these patients reliably, transthoracal and transesophageal echocardiography would have been necessary in 89% of the entire group of patients (all with clinically cardiological abnormalities, pathological routine ECG, without vascular risk factors, or no atherosclerosis in duplex sonography), and Holter-electrocardiography in 54%.     

Axon guidance factor netrin-1 and its receptors regulate angiogenesis after cerebral ischemia

Neurogenesis and angiogenesis play important roles in functional recovery after ischemic stroke. When cerebral ischemia occurs, axon regeneration can compensate for the loss of apoptotic neurons in the ischemic area. The formation of new blood vessels ameliorates the local decrease in blood supply, enhancing the supply of oxygen and nutrients to newly-formed neurons. New blood vessels also act as a scaffold for the migration of neuroblasts to the infarct area after ischemic stroke. In light of this, researchers have been actively searching for methods to treat cerebral infarction. Netrins were first identified as a family of proteins that mediate axon guidance and direct axon migration during embryogenesis. Later studies have revealed other functions of this protein family. In this review, we focus on netrin-1, which has been shown to be involved in axon migration and angiogenesis, which are required for recovery after cerebral ischemia. Thus, therapies targeting netrin-1 may be useful for the treatment of ischemic stroke.     

脑缺血再灌注模型大鼠神经生长抑制因子Nogo-A的表达变化

目的 研究大鼠大脑中动脉闭塞再灌注模型神经生长抑制因子Nogo-A的表达变化,探讨Nogo-A在神经再生中的作用.方法 36只雄性SD大鼠260-280g,随机分成6组,分别为正常对照组、缺血2h再灌注1d、3d、7d、14d和28d组.免疫组织化学方法观察缺血侧纹状体在上述各时间点Nogo-A阳性细胞的染色情况(n=3).Western Blot方法检测Nogo.A的蛋白表达(n=3).结果 缺血侧纹状体区域Nogo-A阳性表达细胞于再灌注后ld增加,7d回到正常水平,14d再次增加,28d降低.Nogo-A的蛋白表达与免疫组化结果呈现一致的趋势.结论 Nogo-A在腩梗死的早期(14d)表达增加,抑制了神经的再生;后期(28d)减少,提示可能参与了神经组织的修复和可塑性的形成.     

rhG-CSF改变大鼠局灶性脑缺血预后的初步研究

目的 研究重组人粒细胞集落刺激因子(recombinant human granulocyte colony-stimulating factor，rhG-CSF)对大鼠局灶性脑缺血预后的影响以及与微管相关蛋白(macrotubule-associated protein2，MAP-2)mRNA表达的关系。方法 用线栓法建立大鼠大脑中动脉缺血再灌注模型，观察rhG-CSF对死亡率和神经功能评分的影响。用半定量逆转录-聚合酶链式反应(RT-PCR)方法，测定rhG-CSF用药组和非用药组的MAP-2 mRNA表达水平的改变。结果 比较rhG-CSF治疗组与非用药组：治疗组大鼠，局灶性脑缺血再灌注后死亡率显著降低，神经功能评分明显改善。治疗组缺血侧脑组织的MAP-2 mRNA表达明显提前恢复正常。结论 一定剂量的rhG-CSF可以减轻脑缺血再灌注损伤，保护神经元，改善功能预后。     

Hydrogen sulfide treatment induces angiogenesis after cerebral ischemia

Hydrogen sulfide (H₂S) is a potent vasodilator and regulates cardiovascular homeostasis. Furthermore, H₂S has a crucial role in ischemia?reperfusion injuries, especially of the heart, liver, and kidneys. This study indicates that treatment with hydrogen sulfide is able to restore neurological function after ischemic stroke by promoting angiogenesis. Treatment with H₂S augments angiogenesis in the peri‐infarct area, and it significantly improves functional outcomes after 2 weeks in a rat MCAO model. H₂S promotes the phosphorylation of AKT and ERK and increases the expression of vascular endothelial growth factor (VEGF) and angiopoietin‐1 (Ang‐1). H₂S‐treated rats showed more newly synthesized endothelial cells in the ischemic lesion (2.31‐fold, P < 0.01). H₂S‐treated astrocytes increased VEGF and Ang‐1 expression, and the inhibition of phosphatidylinositide 3‐kinase (PI3K)/AKT signaling by LY294002 significantly reduced H₂S‐induced VEGF and Ang‐1 expression in astrocytes. Finally, H₂S stimulated endothelial cell migration (3.92‐fold increase in wound healing assay) and tube formation (3.69‐fold increase, P < 0.001) through PI3K/AKT signaling. In conclusion, treatment with H₂S promotes angiogenesis and thereby contributes to improvement of functional outcome after cerebral ischemia. Our findings strongly suggest that H₂S may be of value in regenerative recovery after stroke. © 2014 Wiley Periodicals, Inc.