葛根素对脑缺血再灌注损伤的保护作用

目的研究葛根素对大鼠全脑缺血再灌注损伤的保护作用及其机制.方法采用4血管闭塞法建立SD大鼠全脑缺血再灌注模型,并给予葛根素干预,于缺血再灌注后6、24、72 h、5、7 d进行HE染色及免疫组织化学染色,分别检测大鼠脑组织海马CA1区神经元数目、形态变化和bc1-2表达.结果 (1)脑缺血再灌注后6、24 h海马CA1区神经元未见明显死亡,再灌注后72 h、5、7 d葛根素组神经元存活数目显著高于无药物干预的再灌注组;(2)葛根素组与再灌注组比较各时间点bc1-2表达均明显增多;(3)葛根素组与再灌注组神经元存活数目与bc1-2阳性细胞数均呈显著正相关.结论葛根素对脑缺血再灌注损伤有保护作用,可延缓迟发性神经元死亡的发生,其机制可能与葛根素上调抗调亡基因bc1-2表达有关.     

沙土鼠脑缺血后海马CA1区神经细胞凋亡、相关基因表达及亚低温的干预作用

目的 研究沙土鼠脑缺血后海马CA1区神经细胞凋亡、相关基因表达及亚低温的干预作用. 方法 72只沙土鼠采用随机数字表法分为假手术组(SH)、低温假手术组(HSH)、常温再灌注组(IR)和低温再灌注组(HIR).采用双侧颈总动脉阻断5 min制作脑缺血再灌注损伤模型,各组依术后处死动物时间的不同再分为1、3、7d亚组(n=6),在预定时间点行开阔法迷宫检查、TUNEL法检测海马CA1区神经细胞的凋亡、免疫组化检测肿瘤抑制基因p53、核因子-kB的表达情况.结果 常温状态下脑缺血5 min可诱导沙土鼠1、3、7d的探索活动增加(P<0.051.亚低温状态下仅缺血再灌注后1 d探索活动增加(P<0.05);TUNEL与免疫组化染色显示海马CA1区神经细胞凋亡数量及p53蛋白和NF-KB表达增加,亚低温对以上过程有明显抑制作用(P均<0.05). 结论 海马CA1区p53蛋白和NF-KB表达增加可能是沙土鼠脑缺血5 min神经元凋亡的机制之一,亚低温脑保护机制可能与其对此过程的抑制作用有关.     

大蒜素对全脑缺血再灌注损伤大鼠海马凋亡相关蛋白表达的影响

目的观察大蒜素对全脑缺血再灌注损伤大鼠海马凋亡相关蛋白表达的影响,进一步探讨大蒜素的脑保护机制。方法雄性Wistar大鼠30只,随机分为5组:假手术组(Sham组);缺血再灌注组(IR组);缺血再灌注+大蒜素10 mg/kg(All-10 mg)、20 mg/kg(All-20 mg)、30 mg/kg(All-30 mg)组,夹闭两侧颈总动脉8 min再灌注24 h建立大鼠全脑缺血再灌注模型,取海马组织硫堇染色观察海马组织学改变及存活神经元密度;免疫组织化学染色测定海马CA1区Bcl-2、Bax蛋白的表达。结果与Sham组相比,IR组海马CA1区神经元密度明显降低,Bax蛋白表达明显增加(均P0.05);与IR组相比,大蒜素处理各组海马CA1区神经元密度明显增多,Bcl-2蛋白表达明显增加,Bax蛋白表达明显减少,其中以All-20 mg组变化最显著(均P0.05)。结论大蒜素可以通过影响凋亡相关蛋白的表达而抑制细胞凋亡,从而发挥脑保护作用。     

亚低温对缺血性神经元凋亡、细胞色素C释放的影响

通过大鼠短暂全脑缺血模型来探讨亚低温对大鼠脑缺血后细胞色素C(CytochromeC ,CytC)释放及缺血性神经元凋亡的影响 ,揭示亚低温的部分神经保护机制。用原位细胞凋亡检测法 (TUNEL染色 )检测及电镜观察脑缺血后大鼠脑海马CA1区神经元凋亡发生情况 ;免疫组织化学法测定脑缺血后大鼠脑海马区神经元中细胞色素C释放情况。结果显示 :①低温缺血组海马CA1区凋亡神经元数明显少于常温缺血组 (P <0 .0 1) ;②低温缺血3h组海马CA1区神经元CytC阳性表达低于常温缺血 3h组 (P <0 .0 1)。据此认为 ,全脑缺血后的迟发性神经元死亡很可能经由凋亡途径 ,而CytC激活、释放是缺血性神经元凋亡的一个关键事件。亚低温可抑制CytC的释放 ,推测经此途径减少缺血性神经元凋亡而发挥一定的神经保护作用。     

大鼠全脑缺血再灌注损伤后海马CA1区神经元酪氨酸羟化酶和多巴胺-β-羟化酶表达的变化

目的　研究大鼠全脑缺血再灌注损伤后酪氨酸羟化酶 (TH)和多巴胺 β 羟化酶 (DβH)表达的改变及意义。方法　利用改良四血管闭塞法 ,建立大鼠全脑缺血模型。于缺血再灌注后 1,3,5d断头取脑 ,行免疫组化染色 ,在光镜下观察海马CA1区神经元TH及DβH表达的变化 ,并计数海马CA1区正常神经元。结果　全脑缺血再灌注后 1d ,TH及DβH的表达呈阴性 ,海马CA1区神经元未见显著的病理形态学改变 ;全脑缺血再灌注后 3d ,TH及DβH呈阳性表达 ,海马CA1区可见部分神经元死亡 ;全脑缺血再灌注后 5d ,TH及DβH呈明显阳性表达 ,海马CA1区可见大部分神经元死亡。结论　全脑缺血再灌注后 ,由于TH及DβH异常表达 ,使得儿茶酚胺生物合成增加 ,这可能是短暂性脑缺血损伤的机理之一。     

Tat-GluR6-9c抑制MLK3-MKK7-JNK信号通路对脑缺血再灌注大鼠海马CA1区神经元的保护作用

目的 探讨小肽Tat-GluR6-9c对混合性的谱系激酶3(MLK3)、丝裂原活化的蛋白激酶激酶7(MKK7)、c-Jun氨基末端激酶(JNK)的磷酸化水平及蛋白表达的影响,以及对海马CA1区神经元损伤的影响. 方法 采用4-血管阻塞方法建立大鼠全脑缺血模型,应用免疫印迹的方法分别检测小肽Tat-GluR6-9c对缺血再灌注6h时MLK3、缺血再灌注3d时JNK的磷酸化及蛋白表达水平的影响;采用免疫印迹、免疫组织化学的方法检测小肽Tat-GluR6-9c对缺血再灌注1d时MKK7的磷酸化及蛋白表达水平的影响;采用焦油紫染色方法检测缺血再灌注5d时小肽Tat-GluR6-9c对大鼠海马CA1区神经元损伤的影响. 结果 Tat-GluR6-9c组MLK3、MKK7及JNK磷酸化水平显著低于缺血再灌注组及对照肽组,海马CA1区神经元存活的数量明显多于缺血再灌注组及对照肽组,差异有统计学意义(P＜0.05). 结论 小肽Tat-GluR6-9c能显著抑制脑缺血再灌注诱导的MLK3、MKK7及JNK的磷酸化高峰,降低海马CA1区神经元的损伤.     

大鼠全脑缺血再灌注损伤后海马CAl区神经元酪氨酸羟化酶和多巴胺—β—经化酶表达的变化

目的 研究大鼠全脑缺血再灌注损伤后酪氨酸羟化酶(TH)和多巴胺—β—羟化酶(DβH)表达的改变及意义。方法 利用改良四血管闭塞法，建立大鼠全脑缺血模型。于缺血再灌注后1，3，5d断头取脑，行免疫组化染色，在光镜下观察海马CA1区神经元TH及DβH表达的变化，并计数海马CAl区正常神经元。结果 全脑缺血再灌注后1d，TH及DβH的表达呈阴性，海马CA1区神经元末见显著的病理形态学改变；全脑缺血再灌注后3d，TH及DβH呈阳性表达，海马CA1区可见部分神经元死亡；全脑缺血再灌注后5d，TH及DβH呈明显阳性表达，海马CA1区可见大部分神经元死亡。结论 全脑缺血再灌注后，由于TH及DβH异常表达，使得儿茶酚胺生物合成增加，这可能是短暂性脑缺血损伤的机理之一。     

亚低温对缺血性神经元凋亡、细胞色素C释放的影响

通过大鼠短暂全脑缺血模型来探讨亚低温对大鼠脑缺血后细胞色素c(Cytoehrome c,CytC)释放及缺血性神经元凋亡的影响,揭示亚低温的部分神经保护机制.用原位细胞凋亡检测法(TUNEL染色)检测及电镜观察脑缺血后大鼠脑海马CAi区神经元凋亡发生情况;免疫组织化学法测定脑缺血后大鼠脑海马区神经元中细胞色素C释放情况.结果显示:①低温缺血组海马CAi区凋亡神经元数明显少于常温缺血组(P<0.01);②低温缺血3 h组海马CA1区神经元CytC阳性表达低于常温缺血3 h组(P<0.01).据此认为,全脑缺血后的迟发性神经元死亡很可能经由凋亡途径,而CytC激活、释放是缺血性神经元凋亡的一个关键事件.亚低温可抑制CytC的释放.推测经此途径减少缺血性神经元凋亡而发挥一定的神经保护作用.     

硫酸镁对脑缺血再灌注大鼠脑组织Bcl-2表达的影响及神经保护作用

目的探讨硫酸镁对脑缺血再灌注大鼠脑组织抗凋亡蛋白Bcl-2表达的影响及脑保护作用。方法将32只大鼠随机分为缺血组(n=15)、硫酸镁组(n=15)和正常对照组(n=2)。采用改良的Pulsinelli法建立脑缺血再灌注大鼠模型;制模后分别给予缺血组和硫酸镁组大鼠腹腔注射生理盐水(1.5 ml/d)及硫酸镁(90 mg/kg.d)。缺血再灌注第1、3、7 d分别观察各组大鼠海马CA1区病理学改变和Bcl-2的表达水平。结果正常对照组大鼠海马CA1区神经细胞数量多,排列整齐。缺血再灌注1 d时,缺血组及硫酸镁组大鼠海马CA1区神经元均未见明显死亡;3 d时,缺血组海马CA1区神经元可见少量死亡,残存神经细胞呈较严重缺血性改变,硫酸镁组海马CA1区神经元无明显死亡;7 d时,缺血组海马CA1区神经元大部分死亡,伴有小胶质细胞增生,硫酸镁组仅见部分神经元死亡。与缺血组相比,硫酸镁组神经元受损程度较轻,坏死区较小。硫酸镁组缺血再灌注各时间点大鼠Bcl-2阳性细胞较缺血组均明显增加(均P<0.05)。结论硫酸镁能上调脑组织Bcl-2的表达,对缺血再灌注大鼠的脑组织有明显的保护作用。     

胰岛素对脑缺血后鼠海马CA1区神经元凋亡及记忆影响

目的　观察胰岛素对全脑缺血后海马CA1区神经元凋亡及大鼠学习记忆力改变的影响 ,探讨胰岛素对全脑缺血后海马CA1区神经元产生中枢直接保护作用的机理。方法　利用 4 VO法制作大鼠全脑缺血模型。造成脑缺血 15min后行再灌注 ,于再灌注后即刻经脑室注入 1U胰岛素 ,利用免疫组化及原位标记法分别于全脑缺血后 1、3d观察海马CA1区Bcl 2、Bcl xl蛋白表达及神经元凋亡的情况 ;缺血后 8周 ,利用“Y”型迷宫测试大鼠的学习记忆功能。结果　全脑缺血后 3d ,缺血组大鼠海马CA1区Bcl 2、Bcl xl蛋白的表达呈阴性 ,海马CA1区原位标记阳性细胞计数为 14 3.5± 11.6。治疗组大鼠海马CA1区Bcl 2、Bcl xl蛋白呈阳性表达 ,海马CA1区原位标记阳性细胞计数为 75 .6±6 .7。全脑缺血后 8周 ,治疗组大鼠学习记忆力明显好于缺血组。结论　全脑缺血后脑室内注入胰岛素可促进海马CA1区Bcl 2、Bcl xl蛋白表达 ,减少神经元的凋亡 ,进而减轻脑缺血后大鼠的学习记忆力损害 ,这可能是其对全脑缺血后海马CA1区神经元产生中枢直接保护作用主要机理之一     

Relationship between transmembrane signal transduction pathway and DNA repair and the mechanism after global cerebral ischemia-reperfusion in rats

Objective

To investigate the protein levels of phospho-ERK and phospho-APE/Ref-1 in hippocampal neurons after global cerebral ischemia reperfusion in rats, and observe the relationship between transmembrane signal transduction and repair of DNA damage. The role of ERK signal transduction pathway following global cerebral ischemia reperfusion in rats is further discussed.

Methods

Ninety healthy male SD rats were divided into 3 groups randomly: Sham group (S group), Ischemia reperfusion group (IR group) and Pd98059 pretreatment/ischemia reperfusion group (PD group). Global cerebral ischemia reperfusion model was established by four-vessel occlusion (4-VO) method, and reperfusion was performed 5 minutes following ischemia. Protein levels of phospho-ERK and phospho-APE/Ref-1 were detected using immunohistochemical method at 2 h, 6 h, 12 h, 24 h, 48 h and 72 h after reperfusion, and neuron apoptosis was observed by HE and TUNEL staining.

Results

In CA1 region of IR group, TUNEL positive cells began to appear at 6 h after IR, and reached the apex during 24 h to 48 h. However, TUNEL positive was most strongly exhibited in PD group. In IR group, phospho-ERK was obviously detected in CA3 region at 2 h after IR, and its level was gradually decreased from 6 h until totally absent at 48 h. Besides, phospho-ERK expression in PD group was weaker than that in IR group. For phospho-APE/Ref-1, its expression began to appear in CA1 region in IR group at 2 h after IR, with no obvious changes during 2 h to 12 h. Phospho-APE/Ref-1 expression began to decrease at 24 h and this decrease continued thereafter. Expression level of phospho-APE/Ref-1 in PD group was lower than that in IR group. Results showed the concurrence of decreased phospho-ERK expression level and increased neuron apoptosis after cerebral ischemia reperfusion, the former of which was consistent with the decrease of phospho-APE/Ref-1 expression. Also, the greater the inhibition of ERK phosphorylation was, the greater decrease of APE/Ref-1 expression occurred.

Conclusion

Activation of ERK signal transduction pathway increased the expression of phospho-APE/Ref-1, and thus faciliated the repair of DNA damage. So, activation of ERK signal transduction pathway may protect neurons from apoptosis after cerebral ischemia reperfusion.     

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.     

大鼠脑缺血再灌流后海马氨基酸水平变化与神经元损害的关系探讨

目的探讨脑缺血再灌流后海马氨基酸递质变化与神经元损害的关系。方法建立大鼠前脑缺血再灌流模型,测定海马ＣＡ１区和ＣＡ３／齿状回区游离氨基酸含量,观察阻断隔－海马通路对海马神经元损害和氨基酸水平的影响。结果（１）海马结构中仅ＣＡ１区神经元明显损害,但ＣＡ１区和ＣＡ３／齿状回区的Ｇｌｕ、Ａｓｐ和ＧＡＢＡ含量无差异。（２）阻断隔－海马通路可明显减轻海马神经元损害,但对海马氨基酸水平变化无影响。结论脑缺血再灌流后,氨基酸递质水平的异常变化不是海马ＣＡ１区神经元选择性易损的唯一决定因素,隔－海马通路末梢释放的神经递质也参与海马神经元损害过程。     

亚低温对大鼠短暂全脑缺血后神经元凋亡的影响

目的 探讨亚低温对大鼠脑缺血后神经元凋亡的影响，揭示亚低温的部分神经保护机制。方法 采用“双侧颈总动脉阻断＋全身低血压”方法来建立大鼠短暂性全脑缺血模型。用神经元尼氏体亚甲兰特殊染色法观察大鼠脑缺血后海马CA1区神经元损害情况；原位细胞凋亡检测法（TUNEL染色）及电镜观察脑缺血后CA1区神经元凋亡情况。结果 与假手术组、低温缺血组相比，常温缺血组海马CA1区神经元缺失明显（P＜0．01）。常温及低温缺血组海马CA1区均存在神经元凋亡，但低温缺血组海马CA1区凋亡神经元数明显少于缺血组（P＜0．01）。结论 经“双侧颈总动脉阻断＋全身低血压”方法建立的大鼠短暂全脑缺血模型证实了亚低温的脑保护作用。全脑缺血后的迟发性神经元死亡很可能经由凋亡途径，而亚低温可通过抑制缺血性神经元凋亡而发挥一定的神经保护作用。     

Pergolide protects CA1 neurons from apoptosis in a gerbil model of global cerebral ischemia

OBJECTIVE: To investigate the effects of dopamine (DA) receptor agonists and antagonists on neuronal apoptosis in hippocampal CA1 region after forebrain ischemia/reperfusion (I/R) injury in gerbils. METHODS: Gerbil forebrain ischemia was induced by occluding bilateral carotid arteries for 5 minutes. The open field test, hematoxylin-eosin staining and in situ terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) methods were used 1, 3 and 7 days after reperfusion. Western blot was used to examine the phosphorylation of c-Jun. RESULTS: Pergolide could significantly reduce the habituation impairments of ischemic gerbils, increase the number of normal neurons and reduce the number of apoptotic neurons in hippocampal CA1 region after reperfusion. SKF38393, SCH23390 and spiperone had no effects on these changes in this transient I/R injury model. Furthermore, pergolide can significantly reduce the phosphorylation of c-Jun induced by transient forebrain ischemia.     

Mild hypothermia increases Bcl-2 protein expression following global cerebral ischemia.

Mild hypothermia protects the brain against experimental ischemia, but the reasons are not well known. We examined whether the protective effects of mild hypothermia could be correlated with alterations in expression of Bcl-2, an anti-apoptotic protein in a rat model of transient global ischemia. Following 10 min of forebrain ischemia, hippocampal neurons were examined 72 h later for survival, expression of Bcl-2 family proteins and apoptosis. Intraischemic mild hypothermia was applied for 3 h (33 degrees C, isch-33) or normal body temperature was maintained (37 degrees C, isch-37). Survival of CA1 neurons was significantly improved in the isch-33 group compared to the isch-37 group (90 vs. 53% survival; P<0.01). The proportion of Bcl-2-positive cells among surviving CA1 neurons in the isch-33 group was increased compared to that of sham and isch-37 groups (P<0.01). Bax expression in CA1 was no different between sham and isch-33 groups, but was significantly decreased in isch-37 (P<0.05). TUNEL staining was positive in many isch-37 CA1 neurons, but absent in isch-33. Utilizing electron microscopy, more cells meeting criteria for apoptosis were observed in the isch-37 than isch-33. These data suggest that mild hypothermia attenuates apoptotic death, and that this protection may be related to increases in Bcl-2.     

Global cerebral ischemia due to cardiocirculatory arrest in mice causes neuronal degeneration and early induction of transcription factor genes in the hippocampus

To analyze the role of specific genes and proteins in neuronal signaling cascades following global cerebral ischemia, it would be useful to have a reproducible model of global cerebral ischemia in mice that potentially allows the investigation of mice with specific genomic mutations. We first report on the development of a model of reversible cardiocirculatory arrest in mice and the consequences of such an insult to neuronal degeneration and expression of immediate early genes (IEG) in the hippocampus. Cardiocirculatory arrest of 5 min duration was induced via ventricular fibrillation in mechanically ventilated NMRI mice. After successful cardiopulmonary resuscitation (CPR), animals were allowed to reperfuse spontaneously for 3 h (n=7) and 7 days (n=7). TUNEL staining revealed a selective degeneration of a subset of neurons in the hippocampal CA1 sector at 7 days. About 30% of all TUNEL-positive nuclei showed condensed chromatin and apoptotic bodies. Immunohistochemical studies of IEG expression performed at 3 h exhibited a marked induction of c-Fos, c-Jun, and Krox-24 protein in all sectors of the hippocampus, peaking in vulnerable CA1 pyramidal neurons and in dentate gyrus. In contrast, sham-operated animals (n=3) did not reveal neuronal degeneration or increased IEG expression in the hippocampus when compared with untreated control animals (n=3). In conclusion, we present a new model of global cerebral ischemia and reperfusion in mice with the use of complete cardiocirculatory arrest and subsequent CPR. Following 5 min of ischemia, a subset of CA1 pyramidal neurons was TUNEL-positive at 7 days. The expression of IEG was observed in all sectors of the hippocampus, including selectively vulnerable CA1 pyramidal neurons. This appears to be a good model which should be useful in evaluating the role of various genes in transgenic and knockout mice following global ischemia.     

葛根素对大鼠全脑缺血再灌注后学习记忆障碍保护作用及其机制的研究

目的 探讨葛根素对大鼠全脑缺血再灌注后学习记忆能力的影响及其机制。方法 采用四血管阻断法建立SD大鼠全脑缺血再灌注损伤模型，暗回避反应法测定学习记忆能力，并应用免疫组织化学法、原位末端标记法，检测大鼠全脑缺血再灌注海马CA，区的bcl-2阳性细胞数、凋亡细胞数的动态变化。结果 (1)与再灌注组相比，葛根素组大鼠潜伏期明显延长；(2)脑缺血再灌注后，海马CA1区bcl-2蛋白的表达随再灌注时间不同而变化，缺血20min后再灌注24h达高峰，葛根素组bcl2蛋白的表达于相应的时间点明显增多；(3)脑缺血再灌注后海马CA1区神经元凋亡损伤在再灌注72h损伤最重，葛根素组可减少相应时点神经细胞凋亡数。结论 葛根素对全脑缺血再灌注后大鼠学习记忆能力具有明显的改善作用，其作用机制可能与通过上调bcl-2基因表达从而抑制或延迟脑缺血再灌注后细胞凋亡有关。     

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.     

亚低温对局灶性脑缺血再灌注大鼠脑皮质神经元凋亡及存活素、脑源性神经营养因子表达的影响

目的观察亚低温干预对局灶性脑缺血再灌注大鼠脑皮质神经元凋亡及存活累(Survivin)、脑源性神经营养因子(BDNF)表达的影响,探讨Survivin、BDNF在亚低温脑保护机制中的作用。方法采用线栓法制备成年雄性SD大鼠大脑中动脉闭塞(MCAO)局灶性脑缺血再灌注改良模型,将90只大鼠随机分为假手术组、常温缺血组和亚低温缺血组,缺血组分别于缺血3h再灌注3h、6h、12h、24h、48h、72h、7d处死,亚低温缺血组于缺血后10min实施全身亚低温持续3h。进行TUNEL染色及免疫组化染色,检测梗死灶周围皮质神经元凋亡数量和Sur-vivin、BDNF的表达水平。结果 (1)亚低温缺血组和常温缺血组于再灌注6h皮质区均出现TUNEL染色阳性细胞,72h达高峰,随后逐渐减少,两组内相邻时间点比较差异均有统计学意义(P<0.05);在相同时间点亚低温缺血组凋亡细胞数明显少于常温缺血组,两组间比较差异有统计学意义(P<0.05)。(2)亚低温缺血组于再灌注3hSurvivin、BDNF表达有所增加,BDNF于24h达高峰,Survivin于48h达高峰,随后表达逐渐降低,但7d时仍高于假手术组,常温缺血组表达趋势与之相似,两组各时间点Survivin、BDNF表达均高于假手术组,差异有统计学意义(P<0.05);除再灌注3h Survivin表达在亚低温缺血组与常温缺血组间无明显差异外,其余各时间点亚低温缺血组Sur-vivin、BDNF表达均高于常温缺血组,差异有统计学意义(P<0.05)。结论亚低温干预可抑制梗死灶周围脑皮质神经细胞凋亡,促进存活素及脑源性神经营养因子的表达,发挥脑保护作用。