小檗碱对小鼠海马CA1区迟发性神经元坏死的影响

本文采用Ｐｕｌｓｉｎｅｌｌｉ－Ｂｒｉｅｒｌｅｙ４血管结扎致ＳＤ大鼠全脑缺血（１０ｍｉｎ）再灌流模型，分别观察了早期不同再灌流时间（１２、２４、４８ｈ）点上，大鼠海马ＣＡ１区神经元的超微结构以及早灌７ｄ时光镜结构变化，同时观察了小檗碱对ＣＡ１区迟发性神经元坏死的影响。结果显示脑缺血再灌流早期，ＣＡ１区神经元超微结构发生明显改变，７ｄ时光镜下绝大部分细胞脱失，而用药组大鼠海马ＣＡ１区神经元在相应时间点     

保精增智液对大鼠迟发性神经元坏死海马CA_1区光镜和电镜改变的影响

本研究采用Ｗｉｓｔａｒ大鼠４血管关闭法制成全脑缺血１０ｍｉｎ再灌流动物模型造成迟发性神经元坏死（ＤＮＤ），分别观察了海马ＣＡ１区再灌流后３ｄ和５ｄ的普通病理和超微结构改变，同时观察了中药保精增智液对ＤＮＤ的保护作用，结果显示再灌流３ｄ时电镜下ＣＡ１区神经元内亚细胞结构改变明显，５ｄ时光镜下出现明显的神经元脱失，造模前８ｄ给药组可明显改善再灌流３ｄ时的亚细胞结构的改变，使５ｄ时神经细胞存活数上升（１８１．６±１５．１个／ｍｍ，对照组４１．４±４．０，Ｐ＜０．０１）。该药对大鼠短暂全脑缺血再灌流造成的ＤＮＤ有保护作用。     

与缺血性海马CA_1迟发性神经元死亡有关的基因表达改变

短暂脑缺血后海马CA_1区易发生迟发性神经元死亡。缺血后,CA_1神经元线粒体基因、热休克蛋白基因和神经递质系统基因表达改变与迟发性神经元发生有关。CA_1星形细胞基因表达变化也与迟发性神经元死亡有一定的关系。用药物干预后,CA_1部分基因的表达变化,与迟发性神经元死亡率下降的相关性好。     

不同预缺血时间及间隔时间窗对CA_1区锥体细胞的影响

目的 :探讨预缺血时间及间隔时间窗对CA1区锥体细胞的影响。方法 :钳夹沙土鼠的双侧颈总动脉制造脑缺血模型 ,应用尼氏染色观察迟发性神经元坏死。结果 :3 5min前脑缺血再灌流 7d前 ,1min的预缺血时间没有保护作用 ;2min预缺血时间 ,间隔 6h对脑缺血没有保护作用 ,间隔 1、3、5、7d对脑缺血有保护作用 ,间隔 15d对脑缺血保护作用消失。结论 :2min预缺血时间导致脑内复杂的分子生物学变化 ,间隔时窗 1～ 7d对CA1区锥体细胞有保护作用     

脑缺血后迟发性神经元坏死的超微病理

大白鼠4VO模型,全脑缺血10分钟后再灌流1、2、3、5、7天和对照共6组。经心脏灌流固定后取材,电镜下观察。缺血后1天出现核膜不规则、粗面内质网增生,多聚核蛋白体解聚;胞浆内出现致密物和脂褐素颗粒。2天时除上述改变外可见高尔基氏器肿胀,粗面内质网呈板层状排列,神经网肿胀,空泡形成。3天时主要表现核基质肿胀,异染色质增多并附着于核膜;线粒体肿胀、嵴破坏,少数线粒体基质致密,内含绒毛状致密物;高尔基氐器肿胀,周围出现被膜小泡。树突内和突触内可见大量致密小泡。5天和7天时,大部分神经元空化,神经细胞核周围和树突内出现大量的原纤维,胞质内和树突内可见一种指纹状包涵体,呈螺旋状;另一种神经细胞的改变为变暗、固缩,树突迂曲,最后完全崩解。     

迟发性神经元坏死对大鼠胸腺及脾淋巴细胞功能的影响

利用大白鼠四血管结扎再灌流（４ＶＯ）制成迟发性神经元坏死（ＤＮＤ）模型，观察光镜及电镜下的病理特点；同时利用该模型观察胸腺、脾脏细胞ＣｏｎＡ反应性、胸腺细胞自发增殖反应和脾脏ＮＫ细胞毒性４项指标。结果发现：在再灌流后的不同时相中，４项免疫指标基本是先增高，后降低，即１～３ｄ增高，５ｄ后普遍降低。提示迟发性神经元坏死时伴有明显的免疫功能的改变。     

小檗碱对小鼠全脑缺血后神经元凋亡的影响

目的观察小檗碱能否对小鼠全脑缺血后细胞凋亡产生抑制作用.方法利用改良的Pulsinelli-Brierley4血管闭塞法制成小鼠全脑缺血再灌注动物模型.TUNEL法原位检测特征性DNA片段.琼脂糖凝胶电泳技术检测DNA梯度带.结果小檗碱组与再灌流各时间段缺血组相比,海马CA1区TUNEL阳性细胞数明显减少(P<0.01).缺血组再灌注24h、48h可见典型的DNA梯度带,分别在180、360、540bp等处.小檗碱组未见特征性DNA梯度带.结论小檗碱可以减少小鼠全脑缺血后海马CA1区细胞凋亡的发生.     

转化生长因子β-1在全脑缺血再灌注后迟发性神经元坏死时的表达

目的 探讨转化生长因子β-1（TGF-β1）在迟发性神经元坏死时对中枢神经系统的保护与修复作用。方法 采用HE染多功能，尼氏染色，透射电镜，免疫组化及RT-PCR技术。结果 常规光镜及电镜观察均显示再灌注后额叶皮质及海马有不同程度的神经元变性。坏死。免疫组织化学结果及RT-PCR结果均显示皮质与海马区内的TGF-β1在缺血再灌注后呈明显阳性改变。结论 TGF-β1在脑缺血损伤时尤其在发生迟发性神经元坏死时可呈现明显于正常脑组织的表达，因此，TGF-β1不仅在脑缺血早期而且在发生迟发性神经元坏死时，均可能对中枢神经系统产生保护和修复作用。     

小檗碱对小鼠全脑缺血后神经元凋亡相关基因的影响

目的 探讨小檗碱对小鼠全脑缺血后神经元凋亡相关基因的影响,以了解小檗碱保护脑缺血的机制,为其开发利用提供理论依据。方法 利用改良的Pulsinelli-Brierley4血管闭塞法制成小鼠全脑缺血再灌注动物模型。小檗碱用量为1mg/kg,于术前30min,术后每日1次,腹腔注射。免疫组织化学技术检测凋亡相关基因Bcl-2,Bax蛋白的表达。结果 正常组海马区未见Bcl-2或Bax蛋白表达;缺血组再灌注6h海马CA3区可见Bcl-2阳性细胞,24h达到高峰,48h开始下降;小檗碱治疗组再灌注24h、48h及168hBcl-2阳性细胞明显减少（P＜0．01）。缺血组再灌注6h海马CA1区可见Bax阳性细胞;48h达高峰;168h明显下降;小檗碱组再灌注24h,48h及168hBax阳性细胞数明显减少（P＜0．01）。结论 小檗碱可以增加小鼠全脑缺血后海马CA3区bcl-2基因的表达,降低CA1区Bax基因的表达,从而减少凋亡的发生,可能为其保护脑缺血的机制之一。     

大鼠脑缺血后海马CA1区胶质纤维酸性蛋白表达与迟发性神经元死亡的关系

目的观察大鼠大脑缺血再灌注后海马CA1区胶质纤维酸性蛋白(GFAP)的表达与迟发性神经元死亡的关系。方法采用大鼠大脑中动脉阻塞再灌注模型(MCAO),将大鼠随机分为MCAO后3d、7d、30d组及假手术组,应用免疫荧光与TUNEL染色法分别观察脑缺血再灌注后不同时间点缺血侧海马CA1区GFAP表达情况和迟发性神经元死亡(DND)的变化。结果(1)3d组海马DND阳性(DND 组)的MCAO大鼠、海马DND阴性(DND-组)的MCAO大鼠与假手术组大鼠比较,缺血侧海马CA1区GFAP染色的平均光密度无显著性差异(P>0.05),但GFAP阳性细胞的形态发生变化;(2)7d组大鼠缺血侧海马CA1区GFAP阳性细胞大量活化增殖,表现为胞体变大,突起增多;DND( )、DND(-)组海马CA1区GFAP染色的平均光密度较假手术组增高(P<0.01),且DND(-)组的GFAP平均光密度较DND( )组明显增高(P<0.01);(3)30d组大鼠缺血侧海马CA1区GFAP表达呈瘢痕样改变,DND( )、DND(-)组与假手术组比较其GFAP染色的平均光密度明显增高(P<0.05),且DND( )组的GFAP平均光密度较DND(-)组明显增高(P<0.05)。结论大鼠MCAO后星形胶质细胞反应性变化的差异可能与海马CA1区迟发性神经元死亡的发生有关。     

小檗碱对大鼠脑缺血后MCP-1表达的影响

目的探讨小檗碱处理对大鼠脑缺血后单核细胞趋化蛋白-1（MCP-1）表达的影响及小檗碱对脑缺血的神经保护作用。方法建立大鼠短暂性全脑缺血模型，采用尼氏体亚甲蓝染色观察脑缺血后大鼠脑海马CA1区神经元存活情况；采用免疫荧光染色方法检测脑缺血后大鼠缺血脑组织中MCP-1的表达情况。结果（1）与假手术组比较，脑缺血组大鼠脑海马CA1区神经元明显缺失，而小檗碱处理组大鼠脑海马CA1区神经元存活数明显多于缺血对照组；（2）与假手术组比较，脑缺血组大鼠脑缺血区MCP-1表达显著增多，而小檗碱处理显著降低了大鼠脑缺血区MCP-1的阳性表达。结论脑缺血引起MCP-1表达上调，提示MCP-1可能参与脑缺血损伤。小檗碱可抑制缺血脑组织MCP-1的表达，推测其可能经此途径减轻脑缺血的炎症反应而发挥一定的神经保护作用。     

Immunohistochemical investigation of caspase-1 and effect of caspase-1 inhibitor in delayed neuronal death after transient cerebral ischemia

The localization of caspase-1 protein, interleukin-1beta (IL-1beta)-converting enzyme, was immunohistochemically examined in the hippocampal CA-1 subfield by a transient occlusion of bilateral common carotid arteries in Mongolian gerbils. Immunoreactivities for caspase-1 were found in microglias, astrocytes, endothelial cells of capillaries and some non-pyramidal neurons. Immunopositive microglias increased in number from 3 days until 7 days from the transient ischemia, and astrocytes also increased in number from 3 days until 28 days. At the electron microscopic level, caspase-1 immunoreaction endproducts were associated with Golgi apparatus in glial cells, endothelial cells of blood vessels and non-pyramidal neurons. The delayed neuronal death of CA-1 pyramidal cells was significantly protected by the treatment of specific caspase-1 inhibitor (Ac-WEHD-CHO) or broad caspase family inhibitor (z-VAD-FMK). Cell death was protected in a dose dependent manner by the former by 43-57%, and by the latter by 66-91% when injected at 1 and 10 microg, respectively. On the other hand, the protective effect of specific caspase-3 inhibitor (Ac-DMQD-CHO) was less significant at higher dose (10 microg) by 33% (P<0.05), and not detectable at lower dose (1 microg) by 13% (P=0.27). Furthermore, a significant decrease of microglias and astrocytes was found in the CA-1 as well as the reduction of IL-1beta and caspase-1 immunoreactivities by the treatment of Ac-WEHD-CHO. Extravasation of serum albumin was also extremely reduced by this treatment. These findings suggest that the inhibition of caspase-1 activity ameliorates the ischemic injury by inhibiting the activity of IL-1beta.     

Delayed neuronal death and delayed neuronal recovery in the human brain following global ischemia

Summary The understanding of delayed hippocampal death as a therapeutic window for post-ischemic treatment of the brain has led to numerous investigations focusing upon underlying cellular mechanisms and pharmacological potentials in gerbils and rats. Nevertheless, studies on the occurrence of delayed neuronal death in the human brain have been singular and dealt with only small files of patients. To complement these limited data, in the present study 26 adult patients with a history of a single cardiac arrest were included. Following successful resuscitation, individual survival ranged from less than 1 h to 186 days ( = 11 days). The severity of the resultant ischemic injury in hippocampus CA1, among Purkinje cells, or in frontal neocortex, respectively, was quantified by direct counting of necrotic neurons. Additionally, hippocampal specimens were immunostained for neuron-specific enolase. The data obtained demonstrate the occurrence of delayed neuronal death in human hippocampus and, in a minor form, in cerebellar Purkinje cells. This is in contrasts to the immediate manifestation of ischemic neuronal necrosis in the neocortex. Unlike previous findings in experimental animals and in humans, the delay of CA1 cell death could be defined as lasting about 7 days following cardiac arrest. Moreover, the immunohistochemical results indicate delayed neuronal recovery in CA1, which in the time course reciprocally corresponds to delayed manifestation of hippocampal neuronal death. Interpretation of the results must consider the lack of information about the exact individual duration of cardiac arrest and resuscitation, as well as missing data concerning pre-ischemic physiological variables.     

The role of early Ca influx in the pathogenesis of delayed neuronal death after brief forebrain ischemia in gerbils

To examine the role of calcium influx in the early phase after brief forebrain ischemia and subsequent delayed neuronal cell death in the hippocampus,⁴⁵Ca autoradiography and electron microscopic cytochemistry, by a combined oxalate-pyroantimonate method, were carried out in gerbil brains after 5 min bilateral common carotid arterial occlusion. Further, neuronal during the ischemic and postischemic periods was determined by conventional or immunohistochemical staining for microtubule-associated protein 2 (MAP2) with and without calcium-entry blockers.⁴⁵Ca autoradiography showed a high peak of calcium in the hippocampus at 5 min of recirculation. Electron cytochemical microscopy also demonstrated accumulation of intracellular calcium pyroantimonate deposits in the neuronal cells in all regions. At 30 min of reperfusion, amounts of calcium in the hippocampus returned to the control levels, and intracellular dense calcium pyroantimonate deposits were reduced in these areas. Loss of the reaction for MAP2 was noted in the medial CA1 of the hippocampus immediately after 5 min ischemia and at 5 and 30 min after reperfusion. MK-801 (10 mg kg⁻¹, anN-methyl-d-aspartate (NMDA) receptor antagonist, injected intraperitoneally 1 h before ischemia, suppressed the early increase of calcium in the forebrain and neuronal cell necrosis in the CA1. However, neither injection of MK-801 30 min after reperfusion nor preischemic treatment with 0.5 mg kg⁻¹ Nicardipine, voltage-sensitive calcium channel antagonists, prevented neuronal death. In immunohistochemical staining for MAP2, the ischemic lesion in the medial CA1 maintained after 5 min ischemia and the subsequent early reperfusion period in the untreated brains was protected by the preischemic injection of 10 mg kg⁻¹ MK-801, but was not restored by the injection of 0.5 mg kg⁻¹ Nimodipine or 1 mg kg⁻¹ Nicardipine. In conclusion, it is suggested that an early excess of calcium influx could be caused mainly by excitatory amino acid overload through NMDA receptor-mediated calcium channels during the ischemic and early postischemic periods.     

Proteasome alteration and delayed neuronal death in hippocampal CA1 and dentate gyrus regions following transient cerebral ischemia

BACKGROUND： Proteasome dysfunction has been reported to induce abnormal protein aggregation and cell death. OBJECTIVE： To investigate the effect of proteasome changes on delayed neuronal death in CA1 and dentate gyrus （DG） regions of the rat hippocampus following transient cerebral ischemia. DESIGN, TIME AND SETTING： A randomized, controlled animal experiment. The study was performed at the Department of Biochemistry and Molecular Biology, Norman Bethune Medical College of Jilin University, from September 2006 to May 2008. MATERIALS： Rabbit anti-19S S10B polyclonal antibody was purchased from Bioreagents, USA; propidium iodide and fluorescently-labeled goat anti-rabbit IgG were purchased from Jackson Immunoresearch, USA; hematoxylin and eosin staining solution was purchased from Sigma, USA; LSM 510 confocal microscope was purchased from Zeiss, Germany. METHODS： A total of 40 healthy Wistar rats, male, 4 months old, were randomly divided into sham surgery group （n = 8） and model group （n = 32）. Ischemic models were established in the model group by transient clamping of the bilateral carotid arteries and decreased blood pressure. After 20 minutes of global ischemia, the clamp was removed to allow blood flow for 30 minutes, 4, 24 and 72 hours, respectively, with 8 rats at each time point. The bilateral carotid arteries were not ligated in the sham surgery group. MAIN OUTCOME MEASURES： Neuronal death in the CA1 and DG regions was observed by hematoxylin-eosin staining. Proteasome expression in CA1 and DG region neurons was detected by immunohistochemistry. RESULTS： Hematoxylin-eosin staining showed neuronal death in the CA1 region alone at 72 hours of reperfusion following ischemia. In comparison to the sham surgery group, a significant decrease in proteasome expression was observed, by immunohistochemistry, in the CA1 and DG regions in the model group, following 30 minutes, 4, 24, and 72 hours of reperfusion （P 〈 0.01）. After 72 hours of reperfusion following ischemia, proteasome expression had almost completely disappeared in the CA1 region. In contrast, neurons of the DG region showed minimized proteasome expression at 24 hours, with a slight increase at 72 hours （P 〈 0.01）. CONCLUSION： The alteration of proteasome following ischemia/reperfusion in the neurons of hippocampal CA1 and DG regions reduces the ability of cells to degrade abnormal protein, which may be an important factor resulting in delayed neuronal death following transient cerebral ischemia.     

一氧化氮合酶抑制剂对缺血性海马迟发性神经元死亡的保护作用

目的：研究一氧化氮在缺血性海马迟发性神经元死亡中的作用,观察非选择性一氧化氮合酶抑制剂Ｎ＾Ｇ－ｎｉｔｒｏ－Ｌ－ａｒｇｉｎｉｎｅ对缺血性海马ＤＮＤ的影响。方法：实验分为假手术组,生理盐水治疗组,Ｌ－ＮＮＡ治疗组。采用大鼠４血管关闭方法制作了全脑缺血再灌流模型,以假手术组为对照,检测了脑缺血１０ｍｉｎ再灌流７２ｈ海马区ＮＯＳ活性的变化并观察计量了海马ＣＡ１区组织病理改变;     

Delayed neuronal death in the rat hippocampus following transient forebrain ischemia

Summary An unusual, slowly progressing neuronal damage has been reported to occur in the gerbil hippocampus following ischemia (Kirino 1982). Delayed neuronal death following ischemia has also been noticed in the rat four-vessel occlusion model (Pulsinelli et al. 1982). By light microscopy this slow neuronal injury in the rat was not different from the previously known neuronal ischemic cell change. This report lead us to the question as to whether neurons in the rat hippocampus are damaged rapidly following an initial latent period or deteriorate slowly and progressively until they display overt changes. To clarify this point, observation was done on the hippocampal CA1 sector of the rat following ischemia. Rats were subjected to four-vessel occlusion, and those which developed ischemic symptoms were perfusion-fixed. Although the change appeared very slowly and lacked microvacuolation of the cytoplasm, neuronal alteration was practically not different from classical ischemic cell change. By electron microscopy, however, the change was detectable when the neurons still appeared intact by light microscopy. An increase in the membranous organelles and deposition of dark substances were the initial manifestations. It seemed that the CA1 neurons deteriorated very slowly and progressively, and that they retained partial viability in the initial phase of the change. In spite of the difference in light-microscopic findings, the mechanisms underlying delayed neuronal death in the rat and gerbil hippocampus seemed to be identical.     

Delayed neuronal death and damage of GDNF family receptors in CA1 following focal cerebral ischemia

Delayed neuronal death (DND) of pyramidal neurons in the CA1 and CA3 regions of the hippocampus has been extensively studied following global brain ischemia, whereas only little is known about DND in this highly vulnerable brain region after focal brain ischemia. In the present study, the distribution and time course of hippocampal neuronal apoptosis were studied following transient middle cerebral artery occlusion (MCAO) in rats 1, 3, 7, 14, and 30 days after the insult. In 60% of the animals, more than 90% of CA1 pyramidal neurons showed strong nick-end labeling (TUNEL) staining at day 3 with fragmentation and marginalization of the nuclei in approximately 40% of these cells. The number of TUNEL-positive cells decreased within the next days, but 30 days after MCAO, some apoptotic neurons were still present. Analysis of the expression of the glial cell line-derived neurotrophic factor (GDNF) and its receptors GFRalpha1, GFRalpha2, and GFRalpha3 using triple immunofluorescence and confocal laser scanning microscopy revealed that in all animals showing marked hippocampal DND, the neuronal staining for GFRalpha1, GFRalpha3, and GDNF decreased prior to the onset of TUNEL staining in CA1. After 7 days, some apoptotic neurons still expressed GFRalpha3, whereas only few showed GFRalpha1 immunoreactivity, indicating that GFRalpha1 may be beneficial for the survival of hippocampal neurons. The data suggest that reduced expression of GDNF and impairment of GFRalpha1/3 may contribute to hippocampal DND after focal brain ischemia.     

大鼠脑缺血再灌注后星形胶质细胞反应性变化差异与海马CA1区的迟发性神经元死亡

BACKGROUND： Blood supply to the hippocampus is not provided by the middle cerebral artery. However, previous studies have shown that delayed neuronal death in the hippocampus may occur following focal cerebral ischemia induced by middle cerebral artery occlusion.
OBJECTIVE： To observe the relationship between reactive changes in hippocampal astrocytes and delayed neuronal death in the hippocampal CA1 region following middle cerebral artery occlusion.
DESIGN, TIME AND SETTING： The immunohistochemical, randomized, controlled animal study was performed at the Laboratory of Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, from July to November 2007.
MATERIALS： Rabbit anti-glial fibrillary acidic protein （GFAP） （Neomarkers, USA）, goat anti-rabbit IgG （Sigma, USA） and ApoAlert apoptosis detection kit （Biosciences Clontech, USA） were used in this study. METHODS： A total of 42 healthy adult male Wistar rats, aged 3–5 months, were randomly divided into a sham operation group （n = 6） and a cerebral ischemia/reperfusion group （n = 36）. In the cerebral ischemia/reperfusion group, cerebral ischemia/reperfusion models were created by middle cerebral artery occlusion. In the sham operation group, the thread was only inserted into the initial region of the internal carotid artery, and middle cerebral artery occlusion was not induced. Rats in the cerebral ischemia/reperfusion group were assigned to a delayed neuronal death （＋） subgroup and a delayed neuronal death （–） subgroup, according to the occurrence of delayed neuronal death in the ischemic side of the hippocampal CA1 region following cerebral ischemia.
MAIN OUTCOME MEASURES： Delayed neuronal death in the hippocampal CA1 region was measured by Nissl staining. GFAP expression and delayed neuronal death changes were measured in the rat hippocampal CA1 region at the ischemic hemisphere by double staining for GFAP and TUNEL.
RESULTS： After 3 days of ischemia/reperfusion, astrocytes with abnormal morphology were detected in the rat hippocampal CA1 region in the delayed neuronal death （＋） subgroup. No significant difference in GFAP expression was found in the rat hippocampal CA1 region at the ischemic hemisphere in the sham operation group, delayed neuronal death （＋） subgroup and delayed neuronal death （–） subgroup （P 〉 0.05）. After 7 days of ischemia/reperfusion, many GFAP-positive cells, which possessed a large cell body and an increased number of processes, were activated in the rat hippocampal CA1 region at the ischemic hemisphere. GFAP expression in the hippocampal CA1 region was greater in the delayed neuronal death （＋） subgroup and delayed neuronal death （–） subgroup compared with the sham operation group （P 〈 0.01）. Moreover, GFAP expression was significantly greater in the delayed neuronal death （–） subgroup than in the delayed neuronal death （＋） subgroup （P 〈 0.01）. After 30 days of ischemia/reperfusion, GFAP-positive cells were present in scar-like structures in the rat hippocampal CA1 region at the ischemic hemisphere. GFAP expression was significantly greater in the delayed neuronal death （＋） subgroup and delayed neuronal death （–） subgroup compared with the sham operation group （P 〈 0.05）. GFAP expression was significantly lower in the delayed neuronal death （–） subgroup than in the delayed neuronal death （＋） subgroup （P 〈 0.05）. The delayed neuronal death rates were 42% （5/12）, 33% （4/12） and 33% （4/12） at 3, 7 and 30 days, respectively, followingischemia/reperfusion. No significant differences were detected at various time points （χ2 = 0.341, P 〉 0.05）.
CONCLUSION： The activation of astrocytes was poor in the hippocampal CA1 region during the early stages of ischemia, which is an important reason for delayed neuronal death. Glial scar formation aggravated delayed neuronal death during the advanced ischemic stage.