Minocycline inhibits 5-lipoxygenase activation and brain inflammation after focal cerebral ischemia in rats

Aim： To determine whether the anti-inflammatory effect of minocycline on postischemic brain injury is mediated by the inhibition of 5-1ipoxygenase （5-LOX） expression and enzymatic activation in rats. Methods： Focal cerebral ischemia was induced for 30 min with middle cerebral artery occlusion, followed by reperfusion. The ischemic injuries, endogenous IgG exudation, the accumulation of neutrophils and macrophage/microglia, and 5-LOX mRNA expression were determined 72 h after reperfusion. 5-LOX metabolites （leukotriene B4 and cysteinyl leukotrienes） were measured 3 h after reperfusion. Results： Minocycline （22.5 and 45 mg/kg, ip, for 3 d） attenuated ischemic injuries, IgG exudation, and the accumulation of neutrophils and macrophage/microglia 72 h after reperfusion. It also inhibited 5-LOX expression 72 h after reperfusion and the production of leukotrienes 3 h after reperfusion. Conclusion： Minocycline inhibited postischemic brain inflammation, which might be partly mediated by the inhibition of 5-LOX expression and enzymatic activation.     

白三烯受体拮抗剂ONO—1078对大鼠局灶性脑缺血的神经保护作用

AIM: To determine whether ONO-1078 (pranlukast), a potent leukotriene receptor antagonist, has neuroprotective effect on focal cerebral ischemia in the rat. METHODS: Focal cerebral ischemia was induced by 30 min of middle cerebral artery (MCA) occlusion and followed by 24 h reperfusion. ONO-1078 (0.003-1.0 mg/kg) or vehicle (saline 1 mL/kg) was ip injected 30 min before MCA occlusion and 2 h after reperfusion. The neurological score, infarct volume, neuron density (in cortex, hippocampus, and striatum), brain edema, and albumin exudation around the vessels were determined 24 h after reperfusion. RESULTS: ONO-1078 slightly improved the neurological deficiency, and dramatically decreased infarct volume and neuron loss which showed a bell shaped dose response effect with highest effect at doses of 0.01-0.3 mg/kg. Enlargement of the ischemic hemisphere and albumin exudation were inhibited at doses of 0.01-1.0 mg/kg. CONCLUSION: ONO-1078 has the protective effect on focal cerebral ischemia in rats, which is partially attributed to the inhibition of brain edema. This may represent a novel approach to the treatment of acute cerebral ischemia with cysteinyl leukotriene receptor antagonists.     

Cannabinoid agonists induce contractile responses through Gi/o-dependent activation of phospholipase C in the bovine ciliary muscle

Oxygen free radicals have been involved in the pathophysiology of cerebral ischemia, especially after spontaneous or thrombolytic reperfusion. In this study with rats, we have combined a severe focal ischemic insult (2 h) and a prolonged reperfusion time (7 days) to assess the possible sustained neuroprotective effect of ebselen (10 or 100 mg/kg), a small, lipophilic organoselenium compound which mimics glutathione peroxidase. Parietal cortical perfusion was measured by laser-Doppler flowmetry, and focal cerebral ischemia was carried out by the intraluminal thread method. We have measured plasma selenium levels, brain reduced glutathione levels, as a marker of oxidative stress, and infarct volume associated with cerebral ischemia. Focal ischemia did not alter reduced glutathione levels, while 60 min reperfusion following ischemia induced a significant (P < 0.05) decrease in reduced glutathione levels of the ipsilateral hemisphere. Pretreatment with ebselen, which induced significant (P < 0.05) increase in plasma selenium levels, did not significantly alter the decrease in reduced glutathione levels. The ischemic insult induced 30% mortality on average, with deaths always occurring within 12-48 h. Surviving rats suffered up to 25% body weight loss 1 week after the ischemic insult. Infarct volumes were 26.8 +/- 4.7% of the hemisphere in placebo-treated rats, 26.6 +/- 3.6% in 10 mg/kg ebselen-treated rats, and 25.6 +/- 6.4% in 100 mg/kg ebselen-treated rats (not significantly different). Single-dose administration of ebselen does not reduce the size of brain infarct resulting from severe focal cerebral ischemia in rats. In contrast to previous studies with relatively earlier endpoints, we have delayed the measurement of infarct volume to 1 week after the ischemic insult.     

Neuroprotection by LY341122, a novel inhibitor of lipid peroxidation, against focal ischemic brain damage in rats

LY341122 (2-(3, 5-di-t-butyl-4-hydroxyphenyl)-4-(2-(4-methylethylaminomethyl-ph enylox y)ethyl)oxazole) is a potent inhibitor of lipid peroxidation which has been shown to protect against global ischemia and traumatic brain injury in rats. The purpose of this study was to examine the effect of LY341122 on ischemic injury in a highly reproducible model of focal cerebral ischemia in rats. Male Sprague-Dawley rats were anesthetized with halothane and subjected to 120 min of temporary middle cerebral artery occlusion by retrograde insertion of an intraluminal nylon suture coated with poly-L-lysine. The drug (LY341122, n=19) or vehicle (phosphate-buffered saline (PBS), n=10) was administered i.v. (as a 5 or 10 mg/kg bolus followed by a 5 or 10 mg/kg/h infusion for 20 h, respectively, starting 1 or 2 h after the onset of middle cerebral artery occlusion). Neurological status was evaluated during middle cerebral artery occlusion (60 min) and daily for 3 days thereafter. Three days after ischemia, brains were perfusion-fixed and infarct volumes and brain edema were determined. LY341122 significantly improved the neurological score compared to vehicle at 24, 48 and 72 h after middle cerebral artery occlusion. Treatment with LY341122 significantly reduced total infarct volume in all treated groups compared to vehicle rats. Cortical infarct volume was significantly reduced by LY341122 treatment in the 10 mg/kg (1 h) and LY341122 10 mg/kg (2 h) groups compared to vehicle rats (14.7+/-9.5 vs. 106.8+/-20.9 mm(3), and 36.9+/-20.1 vs. 106. 8+/-20.9 mm(3), respectively (mean+/-S.E.M.)). Striatal infarct volume was also significantly reduced by treatment with LY341122 in the 10 mg/kg (1 h) group compared to vehicle (23.7+/-3.4 vs. 68. 2+/-6.7 mm(3)). These results demonstrate the neuroprotective efficacy of LY341122 in focal cerebral ischemia.     

Neuroprotective Effects of Acetylsalicylic Acid in Middle Cerebral Artery Occlusion–Induced Brain Ischemia in Rats: Suppression of iNOS,HIF-1α, TNF-α, and Active Caspase-3 Expression

Acetylsalicylic acid (ASA) is neuroprotective through various pharmacological action sites. The aim of this study was to examine the detailed mechanisms underlying the inhibitory effect of ASA in inflammatory and apoptotic responses induced by middle cerebral artery occlusion (MCAO) in rats. In this study, ASA significantly attenuated MCAO-induced focal cerebral ischemia in rats. Administration of ASA at 10–20 mg/kg showed marked reductions in infarct size compared with that of control rats. MCAO-induced focal cerebral ischemia was associated with increases in iNOS, HIF-1α, active caspase-3, and TNF-α mRNA expressions in ischemic regions. These expressions were markedly inhibited by treatment with ASA (20 mg/kg). In conclusion, the neuroprotective effect of ASA may mediate at least a portion of the inhibition of HIF-1α and TNF-α activations, followed by inhibition of apoptosis formation (active caspase-3) and inflammatory response (iNOS), resulting in a reduction in the infarct volume in ischemia-reperfusion brain injury. Thus, ASA treatment may represent an ideal approach to lowering the risk of or improving function in ischemia-reperfusion brain injury–related disorders.     

DY-9760e, a calmodulin antagonist, reduces brain damage after permanent focal cerebral ischemia in cats

DY-9760e (3-[2-[4-(3-chloro-2-methylphenyl)-1-piperazinyl]ethyl]-5,6-dimethoxy-1-(4-imidazolylmethyl)-1H-indazole dihydrochloride 3.5 hydrate), a calmodulin antagonist, provides protection against Ca(2+) overload-associated cytotoxicity and brain injury after cerebral ischemia in rats. In this study, we assessed the effect of DY-9760e on ischemic infarct volume in cats subjected to permanent focal cerebral ischemia. DY-9760e was infused for 6 h, beginning 5 min after occlusion of the middle cerebral artery. The infarct volume was measured at the end of drug infusion. DY-9760e, at the dose of 0.25 but not 0.1 mg/kg/h, significantly reduced cerebral infarct volume without affecting any physiological parameters, and its protective effect was mainly evident in the cerebral cortex, where the penumbra, a salvageable zone, exists. The present study demonstrates that DY-9760e protects against brain injury after focal ischemia in a gyrencephalic animal as well as in the rodents reported previously and suggests its therapeutic value for the treatment of acute stroke.     

蜕皮甾酮对大鼠局灶性脑缺血脂质过氧化损伤的影响

目的观察蜕皮甾酮（EDS）对大鼠局灶性脑缺血脂质过氧化损伤的影响。方法应用大脑中动脉线栓法建立大鼠局灶性脑梗死（MCAO）模型,将大鼠随机分为假手术组、缺血对照组、药物干预组。药物干预组于MCAO术后2h腹腔注射EDS20mg／（kg·d）,每24h给药1次,连续给药2d后测定动脉血血清丙二醛（MDA）含量和超氧化物歧化酶（SOD）活性,同时取脑组织进行2,3,5-三氯苯基四氮唑（TTC）染色测定脑梗死体积。结果MCAO术后48h,药物干预组的血清MDA含量明显降低,SOD活性增高,梗死体积较缺血对照组明显减小,两组之间的差异均有显著性（P小于0．05或0．01）。结论EDS能拮抗脑缺血引起的SOD活性下降及MDA含量增高,具有抑制脑组织脂质过氧化损伤的作用。     

油酰乙醇胺在小鼠急性局灶性脑缺血再灌注损伤中的作用及机制

目的研究油酰乙醇胺(OEA)在脑缺血再灌注损伤中的作用及机制。方法线栓法制备小鼠大脑中动脉栓塞模型,缺血90 min后再灌注。应用HPLC-MS/MS方法测定脑组织内OEA的含量。给予OEA(5,10,40 mg/kg,ig)或OEA水解酶抑制剂URB597(1 mg/kg,ig),观察其对小鼠急性脑缺血再灌注损伤的影响。测定脑组织丙二醛(MDA)含量,超氧化物歧化酶(SOD)及过氧化氢酶(CAT)的活性。观察MK886对OEA抗脂质过氧化损伤的影响。结果脑缺血再灌注后6 h,损伤侧脑内OEA含量开始升高,再灌注后24 h升高最明显。脑缺血再灌注后给予OEA(40 mg/kg)或URB597(1 mg/kg)可减少神经功能缺失评分,减小脑梗死体积,减轻脑水肿程度。OEA可减少脑内MDA含量,增加抗氧化酶SOD的活性。OEA这一抗氧化作用可被MK886所取消。结论脑缺血再灌注可增加脑内OEA的含量,OEA通过激动PPARα,减轻脂质过氧化损伤发挥抗脑缺血再灌注损伤作用。     

In vivo neuroprotective effects of ACEA 1021 confirmed by magnetic resonance imaging in ischemic stroke

The neuroprotective activity of ACEA 1021 (5-nitro-6,7-dichloro-1,4-dihydro-2,3-quinoxalinedione; licostinel), a selective antagonist at the strychnine-insensitive glycine site associated with the NMDA receptor complex, has been investigated in various models of focal cerebral ischemia. In isoflurane-anaesthesised Wistar rats with permanent ipsilateral carotid artery ligation and transient middle cerebral artery occlusion (duration of occlusion, 2 h) followed by reperfusion (24 h), intravenous administration of ACEA 1021 (bolus: 10 mg/kg, 15 min after the onset of middle cerebral artery occlusion; infusion: 7 mg/kg/h for 6 h beginning 30 min after occlusion of the artery) produced a 32% reduction in infarct volume. Similarly, in Sprague-Dawley rats with transient middle cerebral artery occlusion (2 h) followed by 24 h of reperfusion, identical treatment with ACEA 1021 decreased infarct size by 39%. Magnetic resonance imaging (MRI) confirmed these effects in the transient model, in that infarct volume observed using apparent diffusion coefficient (ADC) maps was significantly smaller after 24 h in the ACEA 1021-treated rats compared with Tris-treated controls. Furthermore, the increase in perfusion signal intensity after reperfusion was more pronounced in the ACEA 1021-treated rats than in controls. In Fisher 344 rats with permanent occlusion of the middle cerebral artery, ACEA 1021 induced a dose-related decrease in infarct volume, which was associated with an improvement in neurological outcome as measured by the rope suspension procedure. Administration of the same dose regimen, as above, in Fisher rats with permanent middle cerebral artery occlusion reduced infarct volume by 68%. This dose was as effective when administration was delayed for 2 h. In mice with permanent middle cerebral artery occlusion, ACEA 1021 (5 mg/kg, i.v., 5 min after occlusion; 30 mg/kg, s.c., 1 and 4 h post-middle cerebral artery occlusion) decreased infarct size by 42%. The consistent anti-ischemic effects of ACEA 1021 make it a valuable compound for exploratory stroke research.     

豨莶草总黄酮对大鼠脑缺血损伤的保护作用及其作用机制研究

目的 探讨豨莶草总黄酮对大鼠局灶性脑缺血损伤的影响及其作用机制。方法 将SD大鼠随机分为6组:假手术组、模型组、银杏叶片(50 mg/kg)组及豨莶草总黄酮低、中、高剂量(5、10、20 mg/kg)组。采用线栓法建立大鼠局灶性脑缺血模型。观察豨莶草总黄酮对大鼠神经行为、脑梗死面积和脑组织含水量的影响。测定大鼠脑组织中丙二醛(MDA)含量及超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)的活性。结果 豨莶草总黄酮可明显改善大鼠神经功能缺陷,减轻脑水肿,减少脑梗死面积,降低脑组织MDA含量,提高脑组织SOD及GSH-Px的活性。结论 豨莶草总黄酮有抗脑缺血损伤作用,作用机制可能与其抗氧化作用有关。     

Enalapril and moexipril protect from free radical-induced neuronal damage in vitro and reduce ischemic brain injury in mice and rats.

Angiotensin-converting enzyme inhibitors have been demonstrated to protect spontaneously hypertensive rats from cerebral ischemia. The present study investigated the protective effect of enalapril and moexipril in models of permanent focal cerebral ischemia in normotensive mice and rats. To elucidate the mechanism of neuroprotection the influence of these angiotensin-converting enzyme inhibitors on glutamate-, staurosporine- or Fe2+/3+-induced generation of reactive oxygen species and neuronal cell death in primary cultures from chick embryo telencephalons was studied. Treatment with moexipril or enalapril dose-dependently reduced the percentage of damaged neurons, as well as mitochondrial reactive oxygen species generation induced by glutamate, staurosporine or Fe2+/3+. Furthermore, moexipril and enalapril attenuated staurosporine-induced neuronal apoptosis as determined by nuclear staining with Hoechst 33258. In mice, 1 h pretreatment with enalapril (0.03 mg/kg) or moexipril (0.3 mg/kg) significantly reduced brain damage after focal ischemia as compared to control animals. Additionally, moexipril (0.01 mg/kg) was able to reduce the infarct volume in the rat model after focal cerebral ischemia. The results of the present study indicate that the angiotensin-converting enzyme inhibitors enalapril and moexipril promote neuronal survival due to radical scavenging properties.     

牛磺酸对急性局部脑缺血大鼠脑血流和脑梗死体积的影响

目的 :研究牛磺酸对脑缺血再灌注模型大鼠的局部脑血流和脑梗死体积的影响。方法 :用大脑中动脉栓塞 (MCAO)法制作大鼠急性局部脑缺血再灌注模型 ,分别用 10 ,4 0和 80mg·kg- 1牛磺酸经腹腔注射给药 ,检测缺血 1h和灌注 30min内脑血流 ,再灌注 2 4h后进行神经功能缺损评分并计算脑梗死体积的大小。结果 :MCAO引起大脑中动脉供血区脑血流显著下降 ,牛磺酸可减少脑血流量下降的幅度 ;缺血 1h再灌注 2 4h后 ,模型组脑梗死体积为 (33±s 9) % ,而牛磺酸治疗组脑梗死体积明显缩小 ,各组分别为 (17± 5 ) % ,(12± 5 ) %和 (11± 3) % ;牛磺酸治疗组神经缺损评分比模型组小。结论 :牛磺酸可以增加缺血局部的脑血流量 ,缩小脑梗死体积 ,对急性脑缺血具有脑保护作用。     

COX-2抑制剂对大鼠局灶性脑缺血再灌注损伤的保护作用研究

目的观察选择性环氧合酶2(cyclooxygenase2,COX2)抑制剂尼美舒利(nimesulide)对大鼠局灶性脑缺血/再灌注损伤后神经功能缺陷、脑梗死体积及前列腺素E2(PGE2)含量的影响。方法用线栓法制作大鼠脑缺血/再灌注损伤模型,动物分别于缺血前30min、再灌注后6h、12h给予3个不同剂量尼美舒利(3、6和12mg/kg,ip)或等体积的溶媒。于再灌注后6、12、24h进行神经功能评分;采用TTC染色法测定脑梗死体积;应用ELISA法检测PGE2含量。结果尼美舒利呈剂量依赖性减少脑梗死体积并改善功能预后,与溶媒组比较有显著性差异;各尼美舒利治疗组脑梗死后PGE2含量和溶媒组相比显著降低。结论尼美舒利对缺血性脑损伤具有明显的保护作用,其保护作用可能与通过减少花生四烯酸环氧酶途径的代谢产物,从而抑制脑缺血后的炎症反应有关。     

Montelukast, a cysteinyl leukotriene receptor-1 antagonist, attenuates chronic brain injury after focal cerebral ischaemia in mice and rats

Objectives Previously we demonstrated the neuroprotective effect of montelukast, a cysteinyl leukotriene receptor‐1 (CysLT₁) antagonist, on acute brain injury after focal cerebral ischaemia in mice. In this study, we have determined its effect on chronic brain injury after focal cerebral ischaemia in mice and rats. Methods After transient focal cerebral ischaemia was induced by middle cerebral artery occlusion, montelukast was intraperitoneally injected in mice or orally administered to rats for five days. Behavioural dysfunction, brain infarct volume, brain atrophy and neuron loss were determined to evaluate brain lesions. Key findings Montelukast (0.1 mg/kg) attenuated behavioural dysfunction, brain infarct volume, brain atrophy and neuron loss in mice, which was similar to pranlukast, another CysLT₁ receptor antagonist. Oral montelukast (0.5 mg/kg) was effective in rats and was more effective than edaravone, a free radical scavenger. Conclusion Montelukast protected mice and rats against chronic brain injury after focal cerebral ischaemia, supporting the therapeutic potential of CysLT₁ receptor antagonists.     

Pranlukast reduces neutrophil but not macrophage/microglial accumulation in brain after focal cerebral ischemia in mice

AIM: To determine whether pranlukast, a cysteinyl leukotriene receptor-1 antagonist, exerts an anti-inflammatory effect on focal cerebral ischemia in mice. METHODS: Focal cerebral ischemia in mice was induced by permanent middle cerebral artery occlusion (MCAO). In addition to neurological deficits, infarct volume, degenerated neurons and endogenous IgG exudation, we detected accumulation of neutrophils and macrophage/microglia in the ischemic brain tissue 72 h after MCAO. Pranlukast was ip injected 30 min before and after MCAO. RESULTS: Pranlukast significantly attenuated neurological deficits, infarct volume, neuron degeneration and IgG exudation. Importantly, pranlukast (0.01 and 0.1 mg/kg) inhibited myeloperoxidase-positive neutrophil, but not CD11b-positive macrophage/microglial accumulation in the ischemic cortical tissue. CONCLUSION: Pranlukast exerts an anti-inflammatory effect on focal cerebral ischemia in the subacute phase that is limited to neutrophil recruitment through the disrupted blood-brain barrier.     

羟基红花黄色素A对实验性脑缺血的保护作用

红花为菊科植物红花(Carthamus tinctoriusL.)的干燥花,是传统的活血化瘀类代表药物[1]。红花的化学成分比较复杂,研究表明,红花的花中含有黄酮类、脂肪酸、色素、挥发油以及多炔等化合物[2]。目前认为,红花活血化瘀的主要成分集中在水溶性的黄色素部分;红花黄色素主要成分有羟基红花黄色素A(hydroxysafflor yellow A,HSYA)、红花明苷A、红花明苷B及其他含量较低的成分。在红花黄色素中含量最高且具有活性的成分为羟基红花黄色素A[2]。作者采用经典的大鼠大脑中动脉阻塞性脑缺血模型,观察HSYA对局灶性脑缺血大鼠的行为评分、缺血区面…     

白三烯拮抗剂ONO-1078对小鼠持续性局灶性脑缺血的作用

目的在小鼠模型研究白三烯拮抗剂{4-氧-8-[对-(4-苯丁氧基)苯甲酰氨基]-2-(5-四唑基)-4H-1-苯并吡喃半水合物(ONO-1078)}对脑缺血的保护作用.方法以大脑中动脉阻塞法诱导持续性局灶性脑缺血.在脑缺血前30min和缺血后60min腹腔注射ONO-1078、尼莫地平或生理盐水(对照).脑缺血24h后,观察神经症状,并测定脑湿重和脑梗死体积.结果ONO-1078(0.01,0.03,0.1mgkg-1)和尼莫地平(0.2 mg*kg-1)减少脑梗死体积;ONO-1078(0.1 mg kg-1)减轻脑湿重,尼莫地平无此作用;ONO-1078和尼莫地平对神经症状无明显作用.结论ONO-1078对持续性局灶性脑缺血有保护作用,提示白三烯拮抗剂可作为急性脑缺血的一种新治疗药.     

Huanglian-Jie-Du-Tang extract protects against chronic brain injury after focal cerebral ischemia via hypoxia-inducible-factor-1α-regulated vascular endothelial growth factor signaling in mice

Huanglian-Jie-Du-Tang (HJDT) is a traditional Chinese herbal formula which is widely used clinically. In this study, we investigated the effects of an aqueous (HJDTaq) and an ethanolic (HJDTet) extract of HJDT on chronic brain injury after focal cerebral ischemia in mice. The ischemia was induced by occlusion of the right middle cerebral artery for 30 min. HJDTaq (4 g/kg) and HJDTet (200, 400, 800 mg/kg) were orally administered for 21 d from day 7 before ischemia to day 14 after ischemia. The survival rate decreased to less than 50% at 35 d after ischemia. HJDTet at 400 mg/kg increased the survival rate. HJDTaq (4 g/kg) and HJDTet (400, 800 mg/kg) significantly attenuated the neurological dysfunction, brain atrophy and infarct volume after ischemia. There were few cells positive for CD31, hypoxia-inducible-factor-1α (HIF-1α), vascular endothelial growth factor (VEGF) and Flk-1 in the sham control. After ischemia, the number increased. HJDTaq (4 g/kg) and HJDTet (400 or 800 mg/kg) further increased the numbers of CD31, HIF-1α, VEGF and Flk-1-positive cells in the ischemic hemisphere. We conclude that HJDTaq and HJDTet have neuroprotective effects on chronic brain injury after focal cerebral ischemia and lead to accelerated angiogenesis by HIF-1α-regulated VEGF signaling.     

Neuroprotection of nicotiflorin in permanent focal cerebral ischemia and in neuronal cultures

Nicotiflorin is a single component extracted from traditional Chinese medicine Flos Carthami. In this study, we investigated its neuroprotection in permanent focal cerebral ischemia model in rats, and in an in vitro model of ischemia. At doses of 2.5, 5 and 10 mg/kg, nicotiflorin administered immediately after the onset of ischemia markedly reduced brain infarct volume and neurological deficits. For primarily cultured neurons suffered 2 h hypoxia followed by 24 h reoxygenation, nicotiflorin significantly attenuated cell death and reduced LDH release. Morphological observation also directly confirmed its protective effect on neuron. These results provided strong pharmacological basis for its potential therapeutic role in cerebral ischemic illness.