The effect of ECr on HSP70 expression and morphologic changes following transient cerebral lschemia in rats

OBJECTIVE To investigate the effect of Cudrania tricuspidata root extract (ECr) on ischemic cerebral damage and the expression of the 70KDa heat shock protein (HSP70) following transient focal ischemia. BACKGROUND The role that ECr plays in cerebral ischemia has not been studied. METHODS Healthy wistar rats were randomized to the normal control group(Group A,n=4),the sham-operated control group(Group B,n=4),the ischemia and reperfusion group (Group C,n=24),the ischemia and reperfiusion after ECr pre- administration group(Group D,n=24).The rats of Group C and Group D were subjected to transient left middle cerebral artery occlusion (MCAO)as described by Zea Longa for 1 hour. Brain sections at the level of striatum were performed for HSP70 immunohistochemistry and morphology.HSP70 positive reactions and morphologic changes were semiquantiratively analyzedl. RESLULTS In the rats of Group A and Group B, there were scarcely HSP70 immunoreactivities either in cortex or in striatal neurons. In the ischemic brain regions for Group C rats,the HSP70 was induced in morphologically intact neurons and endothelial cells at hour 6 after recirculation, increased at hour12,peaked at day I, decreased at day 3,and HSP70 expression only occured in endothelial cells at day7. In Group D rats, the HSP70 was induced in the neurons of left MCA distribution at hour 1 after reperfusion, The changes in expression of HSP70 at different time points in Group D rats was in accord whth in Group C, but the number of HSP70 positive cells in Group D increased more, and HSP70 irnmunoreactivity in the HSP70-postive cells were more intense than in Group C. Histopathological study with HE staining showed no neuron pyknosis in Group A or in Group B. While pykrotic cells were present in the ipsilateral cortex and striatal neurons of MCA territory of Group C rats beginning at 6 hours after roper fusion. The change of histopathology in Group D was lighter at every time point. The number of pyknotic neurons in left MCA distribution was less than in Group C and there was no evident cell damage at 3 days and 7 days of reperfusion in Group D rats. CONCLUSION Our study demonstrated that transient focal cerebral ischenia could induce the HSP70 expression and induce neurons pyknosis.While ECr pre-treatment before transient focal ischemia in rats could increase the expression of HSP70 and reduce neuronal injury. These data suggests that might be able to enhance neuronal ischemic tolerance of the rats and might have prophylactic neuroprotective effect on ischemic cerebral damage in rats.     

EGb761对大鼠局灶性脑缺血再灌注损伤的保护作用

目的 :观察 EGb76 1对大鼠局灶性脑缺血再灌注损伤的保护作用。方法 :45只大鼠随机分为假手术组 (A组 ) ,脑缺血再灌注损伤组 (B组 ) ,EGb76 1治疗组 (C组 ) ,每组 15只。以线栓法制作大鼠脑缺血再灌注损伤模型。每组 10只缺血 6 0 min再灌注 6 0 min后断头处死 ,取脑测定 NO、NOS、MDA和 SOD变化 ,其余 5只缺血 3h再灌注 2 4h后断头处死 ,观察常规病理、Niss小体及凋亡细胞变化。C组于实验前 3天开始灌胃给 EGb76 1(15 0 mg/ kg,每日 2次 ,术前 1h、术后 12 h灌 EGb76 115 0 mg/ kg)。结果 :脑缺血再灌注后 ,B组 NO、MDA含量 ,NOS活性较 A组升高 ,SOD活性降低 (P<0 .0 5 ) ,病理变化明显 ,凋亡细胞增多。C组 NO、MDA含量及 NOS活性降低 ,SOD活性升高 (P<0 .0 5 ) ,C组病理变化减轻 ,凋亡细胞减少 (P<0 .0 5 )。结论 :EGb76 1对大鼠局灶性脑缺血再灌注损伤具有保护作用。     

托吡酯对大鼠脑缺血再灌注后神经细胞凋亡和HSP-70表达的影响

目的 了解托吡酯(topiramate)对大鼠局灶性脑缺血再灌注后神经细胞凋亡和热休克蛋白-70(HSP-70) 蛋白表达的影响,探讨托吡酯的神经保护作用机制.方法 用线栓法制备SD大鼠大脑中动脉阻塞再灌注(MCAO)模型, 托吡酯100mg/kg灌胃,qd,应用原位末端标记(TUNEL) 和HSP-70免疫组化染色分别观察大鼠脑缺血再灌注后神经细胞凋亡和HSP-70表达.结果 脑缺血再灌注后2h即出现凋亡细胞,并逐渐增加,2d达高峰,之后逐渐减少.托吡酯干预后,凋亡神经细胞减少,其中再灌注12～48h与对照组比较差异有显著性.脑缺血再灌注后HSP-70的表达于2h逐渐增加,24h达高峰,72h后逐渐降低.托吡酯干预后, 再灌注12h～72h HSP-70表达较对照组显著升高.结论 HSP-70及神经细胞凋亡均参与了脑缺血的病理生理过程,托吡酯具有抑制细胞凋亡和神经保护作用.     

亚低温对大鼠脑缺血再灌注损伤后HSP70mRNA表达及损伤神经细胞凋亡的影响

目的 探讨亚低温对大鼠脑缺血再注损伤后HSP70mRNA、HSP70（热休克蛋白70）表达及损伤神经细胞凋亡的影响。方法 采用大鼠局灶性脑缺血再灌注损伤模型,大脑中动脉阻塞2小时,再灌注损伤10小时,用逆转录聚合酶链反应（RT－PCR）技术、免疫组织化学法和原位缺口末端标记（TUNEL）法分别检测假手术组、对照组和亚低温组HSP70mRNA、HSP70表达水平和凋亡细胞百分率。结果 亚低温组HSP70mRNA、HSP70表达水平较对照组显著升高（P＜0．05）,而凋亡细胞百分率明显低于对照组（P＜0．05）。结论 亚低温上调大鼠脑缺血再灌注损伤后HSP70mRNA、HSP70表达水平可能与其抗损伤神经细胞凋亡作用有关。     

ＥＧb７６１对星形胶质细胞抗凋亡作用的研究

研究无糖对星形胶质细胞的影响和ＥＧb７６１（Ｇinkgobiloba Extract 761)对细胞损伤后的有效保护浓度及其抗凋亡作用。实验选用２４h后分组：无糖组、ＥＧb７６１药物组和正常组,继续培养72h后,①测定LDH,药物组的LDH释放量低于无糖组和正常组,经样本均数间的两两比较q检验有显著性差异（P＜0.01)。②二倍体细胞比例测定,药物组的凋亡峰明显低于无糖组和正常组,三组间的t检验P＜0.01。③光镜下免疫学观察：体外无糖培养20d的星形胶质细胞的胸体比正常组细胞胞体明显增大,突起断裂,细胞胞浆内出现空泡状物,细胞增殖速度减慢。药物组细胞形态与正常组相比无明显变化。结果提示：一定浓度的ＥＧb７６１对无糖损伤的星形胶质细胞具有保护作用,对正常条件下体外培养的星形胶质细胞有抗凋亡作用。     

Acute administration of Ginkgo biloba extract (EGb 761) affords neuroprotection against permanent and transient focal cerebral ischemia in Sprague-Dawley rats

We examined the neuroprotective action of a standardized extract of Ginkgo biloba leaves (EGb 761) in permanent and transient middle cerebral artery (MCA) occlusion models in Sprague-Dawley rats. Forty-four animals were given either EGb 761 (50-200 mg/kg) or vehicle intraperitoneally, 1 hr before permanent MCA occlusion, to evaluate the dose-response effects. An additional 58 animals received EGb 761 (200 mg/kg) or vehicle, 0.5- 4 hr after permanent MCA occlusion, for establishing the therapeutic window. Delayed treatment was also employed in 110 animals treated with either EGb 761 (100-200 mg/kg) or vehicle at 2-3 hr following transient focal cerebral ischemia induced by MCA occlusion for 2 hr. Neurobehavioral scores were determined 22-24 hr after permanent MCA occlusion and either 3 or 7 days after transient MCA occlusion, and brain infarction volumes were measured upon sacrifice. Local cortical blood flow (LCBF) was serially measured in a subset of animals receiving EGb 761 (100-200 mg/kg) or vehicle, 0.5 hr and 2 hr after permanent and transient MCA occlusion, respectively. Relative to vehicle-treated controls, rats pretreated with EGb761 (100 and 200 mg/kg) had significantly reduced infarct volumes, by 36% and 49%, respectively, and improved sensory behavior (P < 0.05). Delayed treatment with EGb 761 also significantly reduced brain infarction, by 20-29% and 31%, when given up to 2 and 3 hr following transient and permanent MCA occlusion, respectively, whereas improved neurobehavioral scores were noted up to 2 hr after the onset of MCA occlusion (P < 0.05). LCBF was significantly improved in the ipsilateral cortex following the EGb 761 treatment, whereas a higher dose showed a more sustained effect. In conclusion, EGb 761 protected against transient and permanent focal cerebral ischemia and was effective after a prolonged reperfusion period even when therapy is delayed up to 2 hr. This neuroprotection may be at least partially attributed to the beneficial effects of selectively improved LCBF in the area at risk of infarction.     

大鼠局灶性脑缺血再灌流后HSP70表达及其mRNA变化

目的 探讨热休克蛋白７０（ＨＳＰ７０）在局灶脑缺血再灌流后的变化和作用。方法 采用线栓法制备大脑中动脉缺国知再灌流模型。应用免疫组化方法观察ＨＳＰ７０的组织学分布,利用ＲＴ－ＰＣＲ方法检测缺血皮层与基底节区脑组织ＨＳＰ７０ｍＲＮＡ相对含量。结果 基底节区ＨＳＰ７０阳性细胞较少,持续时间短,眼层区ＨＳＰ７０阳性细胞较多,持续时间长。ＲＴ－ＰＣＲ结果表明ＨＳＰ７０ｍＲＮＡ相对含量与免疫组化结果相一致。     

亚低温对大鼠脑缺血再灌注损伤后热休克蛋白70及胶质纤维酸性蛋白表达的影响

目的观察亚低温对大鼠脑缺血再灌注损伤后热休克蛋白70(HSP70)及胶质纤维酸性蛋白(GFAP)表达的影响。方法将雄性Wistar大鼠30只分为假手术组、常温组和亚低温组。制作右侧大脑中动脉阻塞(MCAO)模型,观察缺血2h再灌注48h后各组大鼠脑组织学改变和HSP70及GFAP的表达。结果常温组大鼠脑皮质下神经元严重坏死,亚低温组皮质下神经元坏死严重程度明显较常温组轻,假手术组未见神经元坏死。常温组大鼠脑组织GFAP和HSP70阳性细胞较多,假手术组、亚低温组GFAP和HSP70阳性细胞少于常温组,假手术组偶见HSP70阳性细胞;图像分析显示,常温组大鼠脑组织GFAP、HSP70表达的平均光密度较假手术组和亚低温组明显增高(均P<0.01)。结论亚低温能减轻大鼠脑缺血再灌注损伤,降低脑组织HSP70及GFAP蛋白的表达。     

垂体腺苷酸环化酶激活肽对大鼠脑缺血再灌注损伤后缺血皮层 p-ERK及c-Fos表达的影响

目的观察大鼠局灶性脑缺血再灌注损伤后活化的胞外信号调节激酶和c-Fos的表达变化及垂体腺苷酸环化酶激活肽(PACAP)对其表达的影响。方法采用大鼠局灶性脑缺血再灌注损伤模型,72只大鼠随机分成假手术组、缺血再灌注对照组、缺血再灌注PACAP治疗组,大脑中动脉阻塞2h分别再灌注2、12、24、48h。再灌注后各时间点进行神经功能学评分后处死大鼠,免疫组织化学法分别检测3组大鼠p-ERK及c-Fos表达水平。结果缺血再灌注不同时间点PACAP组大鼠神经功能学评分较缺血再灌注对照组减低。脑缺血诱导JNK活化,缺血再灌注对照组缺血侧皮层p-ERK 2h达高峰后渐下降;c-Fos分别在2、24h表达高峰。与之相比,PACAP组各时间点p-ERK表达升高,24、48h c-Fos表达下降。结论PACAP对局灶性脑缺血再灌注损伤有保护作用,部分依赖于其上调了磷酸化EPK的表达,并下调了延迟表达的c-Fos基因。     

Regional expression of heat shock protein-70 mRNA and c-fos mRNA following focal ischemia in rat brain.

In situ hybridization was used to estimate regional levels of heat shock protein-70 (HSP-70) mRNA and c-fos mRNA in two related models of focal cerebral ischemia. In the first model, permanent occlusion of the distal middle cerebral artery (MCA) alone caused a patchy increase in HSP-70 mRNA by 1 h in the central zone of the MCA territory of the ipsilateral neocortex. Tissue levels of HSP-70 mRNA continued to increase for several hours and remained elevated at 24 h. In contrast to the focal expression of HSP-70, c-fos mRNA was increased throughout the ipsilateral cerebral cortex by 15 min and remained elevated for least 3 h. The wide distribution of c-fos expression suggests it may have been caused by spreading depression. In the second model, severe focal ischemia was produced with a combination of transient (1-h) bilateral carotid artery occlusion and permanent MCA occlusion. Combined occlusion for 1 h without reperfusion caused expression of HSP-70 mRNA only in regions adjacent to the central zone of the MCA territory of the neocortex. However, reperfusion of the carotids for 2 h generated intense expression of HSP-70 mRNA throughout most of the ipsilateral cerebral cortex, white matter, striatum, and hippocampus. The wide-spread increase in HSP-70 mRNA suggests that reperfusion triggered expression in all previously ischemic regions. However, at 24 h of reperfusion, increased levels of HSP-70 mRNA were restricted primarily to the ischemic core of the neocortex. These results suggest that expression of HSP-70 mRNA is prolonged in regions undergoing injury, but is transient in surrounding regions that recover.     

Neuronal apoptosis in cerebral ischemia/reperfusion area following electrical stimulation of fastigial nucleus

Previous studies have indicated that electrical stimulation of the cerebellar fastigial nucleus in rats may reduce brain infarct size, increase the expression of Ku70 in cerebral ischemia/ reperfusion area, and decrease the number of apoptotic neurons. However, the anti-apoptotic mechanism of Ku70 remains unclear. In this study, fastigial nucleus stimulation was given to rats 24, 48, and 72 hours before cerebral ischemia/reperfusion injury. Results from the electrical stim- ulation group revealed that rats exhibited a reduction in brain infarct size, a significant increase in the expression of KuT0 in cerebral ischemia/reperfusion regions, and a decreased number of terminal deoxynucleotidyl transferase dUTP nick end labeling （TUNEL）-positive cells. Double immunofluorescence staining revealed no co-localization of Ku70 with TUNEL-positive cells. However, Ku70 partly co-localized with Bax protein in the cytoplasm of rats with cerebral ischemia/reperfusion injury. These findings suggest an involvement of Ku70 with Bax in the cy- toplasm of rats exposed to electrical stimulation of the cerebellar fastigial nucleus, and may thus provide an understanding into the anti-apoptotic activity of KuT0 in cerebral ischemia/reperfu- sion injury.     

脑缺血再灌流后HSP70蛋白的表达及其与凋亡的关系

目的 :研究脑缺血再灌流后 HSP70蛋白的表达及其与凋亡的关系。方法 :应用免疫组化的方法观察大鼠局灶性脑缺血再灌流后脑组织 HSP70蛋白的表达和细胞凋亡的分布。结果 :缺血 2 h再灌流 0 h即可见 HSP70表达和凋亡细胞 ,HSP70至 2 4h达高峰 ,凋亡细胞数于再灌流后 2 4～ 48h达高峰。结论 :脑缺血诱导 HSP70蛋白的表达和细胞凋亡 ,脑缺血后 HSP70蛋白的表达可能参与抑制细胞凋亡     

bFGF对脑缺血再灌流后HSP70及凋亡的影响

目的：研究外源性碱性成纤维细胞生长因子（bFGF)对脑缺血再灌流后HSP70表达与细胞凋亡的影响,方法：线栓法制成大鼠大脑中动脉闭塞及再灌流模型,用免疫组化及原位末端标记的方法观察大鼠大脑中动脉闭塞2h后再通1－72h脑组织HSP70表达与凋亡细胞的分布,侧脑室注射外源性bFGF,并观察对它们的影响。结果：bFGF组与生理盐水组相比于6－48h各时间点的HSP70表达增高（P＜0．05）,凋亡细胞数明显减少（P＜0．05,P＜0．01）。结论：外源性bFGF可能诱导脑缺血再灌流后HSP70表达和抑制细胞凋亡。     

EGb761 Protects Hydrogen Peroxide-induced Death of Spinal Cord Neurons through Inhibition of Intracellular ROS Production and Modulation of Apoptotic Regulating Genes

The present study was conducted to investigate whether Ginkgo biloba extract (EGb) 761 could protect spinal cord neurons from H₂O₂-induced toxicity. In primary spinal cord neurons isolated from embryonic day 14 rats, H₂O₂ administration resulted in a significant decrease in the survival of spinal cord neurons. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) and Hoechst 33342 nuclear staining showed that these cells die by apoptosis. Such neuronal death, however, was significantly reversed by EGb761 in a dose-dependent manner. Moreover, a marked increase in intracellular free radical generation was found after the H₂O₂ administration which could be reversed almost completely by EGb761, indicating that inhibition of free radical generation is an important mechanism of the anti-apoptosis action of EGb761. Finally, treatment of cells with H₂O₂ for 12 h reduced the expression of Bcl-2, an anti-apoptotic gene, by 70% but showed no effect on the level of Bax, a pro-apoptotic gene. EGb76 treatment, however, significantly reversed H₂O₂-induced reduction of Bcl-2 expression and inhibited Bax expression by 2.3-fold. Thus, our study provided evidence showing that the protective effect of EGb761 on spinal cord neuronal apoptosis after oxidative stress is mediated, at least in part, by its anti-oxidative action and regulation of apoptosis-related genes Bcl-2 and Bax.     

Early c-Fos induction after cerebral ischemia: a possible neuroprotective role.

The role of c-Fos in neurodegeneration or neuroprotection after cerebral ischemia is controversial. To investigate whether early c-Fos induction after ischemia is associated with neuroprotection, rats were subjected to 10 minutes of transient forebrain ischemia and c-Fos expression was examined. Resistant dentate granule cells and neurons in CA2-4 displayed more robust immunoreactivity than vulnerable neurons in the CA1 region of hippocampus during early hours of reperfusion. By 6 hours after reperfusion, c-Fos immunoreactivity was greatly diminished in all areas of the hippocampus. Administration of N-acetyl-O-methyldopamine (NAMDA), a compound previously shown to protect CA1 neurons against ischemia, increased c-Fos immunoreactivity in the CA1 vulnerable region at 6 hours after ischemia and protected SK-N-BE(2)C neurons from oxygen glucose deprivation. Further in vitro study showed that NAMDA potentiated phorbol-12 myristate-13 acetate (PMA)-induced c-Fos expression, AP1 binding activity, and late gene expression determined by chloramphenicol acetyltransferase (CAT) activity from AP1 containing tyrosine hydroxylase promoter-CAT fusion gene in SK-N-BE(2)C neurons. In vivo and in vitro results showed that a neuroprotectant, NAMDA, in concert with another stimulus (for example, ischemia or PMA) up-regulates c-Fos expression and suggested that the early rise of NAMDA-induced c-Fos expression in vulnerable CA1 neurons may account for neuroprotection by means of up-regulating late gene expression for survival.     

银杏叶提取物对大鼠脑缺血再灌注后GFAP和细胞凋亡的影响

目的 研究银杏叶提取物(EGb761)对大鼠局灶性脑缺血再灌注后神经细胞凋亡和星形胶质细胞表达的变化.方法 雄性SD大鼠随机分为假手术组、单纯缺血组、EGb761干预组,线栓法建立大脑中动脉缺血再灌注模型(MCAO),原位末端标记(TUNEL)法观察神经细胞的凋亡情况,免疫组化法观测星形胶质细胞的表达.结果 与单纯缺血...     

脑缺血后脑内HSP70表达的实验研究

热休克蛋白(HSP)是细胞对缺血等应激反应的敏感标记.通过建立大鼠全脑缺血模型,采用HSP70单克隆抗体LSAB免疫组化技术对脑缺血再灌注后的神经元进行了检测.发现在海马CA_3区,齿状回,尾壳核及杏仁核等处的神经元中有HSP70过量表达,并于再灌注后48h达到高峰.初步研究了HSP70在不同神经元中的分布情况,基本肯定不同神经元中HSP70的表达与神经元对缺血的耐受性有关.     

Clomethiazole (ZENDRA, CMZ) improves hind limb motor function and reduces neuronal damage after severe spinal cord injury in rat

The neuroprotective role of the expression of heat shock protein (HSP) and immediate early gene remains unclear. Using immunoelectron microscopy, we examined the ultrastructural integrity of the neurons with expression of c-Fos, c-Jun and HSP70 in gerbils after transient cerebral ischemia and repefusion. Induction of c-Fos and c-Jun was observed in the CA3 region resistant to ischemia, while HSP70 was expressed not only in the CA3 but also in the vulnerable CA1 region. With immunoelectron microscopy, the expression of c-Fos/c-Jun and HSP70 was observed in the neurons which retained neuronal integrity except for mitochondrial swelling and polyribosomal disaggregation. In contrast, the CA1 neurons without immunoreaction for HSP70 showed cytoplasmic vacuoles and parallel stacking of rough endoplasmic reticulum, the features associated with the process of delayed neuronal death. These findings suggested that c-Fos and c-Jun were induced selectively in reversibly damaged neurons, whereas HSP70 was up-regulated even in neurons with irreversible damage, but was more preferentially and intensely expressed in neurons with reversible damage. Received: 23 January 1998 / Revised, accepted: 12 June 1998     

Preconditioning with Ginkgo biloba (EGb 761®) provides neuroprotection through HO1 and CRMP2

Ginkgo biloba/EGb 761? (EGb 761) is a popular and standardized natural extract used worldwide for the treatment of many ailments. Although EGb 761 is purported to have a plethora of benefits, here, we were interested to study the neuroprotective properties of EGb 761 and its components and determine whether nuclear factor E2 (Nrf2)/heme oxygenase 1 (HO1) induction of the collapsin response mediator protein 2 (CRMP2) pathway contributes to neuroprotection. Mice were pretreated with EGb 761 or one of its constituents (bilobalide, ginkgolide A, ginkgolide B, and terpene free material [TFM]) for 7days and then subjected to transient middle cerebral artery occlusion (tMCAO) and 48 h of reperfusion. All components except TFM significantly reduced infarct volumes and neurologic deficits. Next, we examined the antioxidant and neuritogenic properties of EGb 761 in primary neurons. Compared with vehicle-treated cells, pretreatment with EGb 761 significantly enhanced the survival of neurons exposed to tertiary butylhydroperoxide (t-BuOOH), hydrogen peroxide (H2O2), and N-methyl-D-aspartate (NMDA). Bilobalide and ginkgolide A also protected cells against NMDA-induced excitotoxicity. Immunofluorescence and Western blot analysis showed that EGb 761 pretreatment significantly increased the protein expression levels of Nrf2, HO1, GAPDH, β-actin, CRMP2, and histone H3 during t-BuOOH-induced oxidative stress. These findings suggest that EGb 761 not only has antioxidant activity but also neuritogenic potential. Demonstrating such effects for possible drug discovery may prove beneficial in stroke and ischemic brain injury.     

Neuroprotective effects of bilobalide, a component of the Ginkgo biloba extract (EGb 761), in gerbil global brain ischemia

The neuroprotective effect of Ginkgo biloba extract (EGb 761) against ischemic injury has been demonstrated in animal models. In this study, we compared the protective effect of bilobalide, a purified terpene lactone from EGb 761, and EGb 761 against ischemic injury. We measured neuronal loss and the levels of mitochondrial DNA (mtDNA)-encoded cytochrome oxidase (COX) subunit III mRNA in vulnerable hippocampal regions of gerbils. At 7 days of reperfusion after 5 min of transient global forebrain ischemia, a significant increase in neuronal death and a significant decrease in COX III mRNA were observed in the hippocampal CA1 neurons. Oral administration of EGb 761 at 25, 50 and 100 mg/kg/day and bilobalide at 3 and 6 mg/kg/day for 7 days before ischemia progressively protected CA1 neurons from death and from ischemia-induced reductions in COX III mRNA. In addition, both bilobalide and EGb 761 protected against ischemia-induced reductions in COX III mRNA in CA1 neurons prior to their death, at 1 day of reperfusion. These results suggest that oral administration of bilobalide and EGb 761 protect against ischemia-induced neuron death and reductions in mitochondrial gene expression.