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。     

亚低温对大鼠脑缺血再灌注损伤后HSP70 mRNA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灌注损伤后HSP70 mRNA、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HSP70 mRNA、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HSP70 mRNA、HSP70表达水平可能与其抗损伤神经细胞凋亡作用有关.     

缺血后处理对大鼠局灶性脑缺血再灌注损伤热休克蛋白70影响

目的探讨缺血后处理(Postcond)对大鼠局灶性脑缺血再灌注损伤热休克蛋白70(HSP70)表达的影响,以探讨其脑保护的机制。方法成年健康SD大鼠45只,随机分为假手术组、缺血再灌注组、缺血后处理组,应用线栓法建立大脑中动脉闭塞(MCAO)再灌注模型,于灌注24h后断头留取大脑皮质组织,用免疫组化、Western blot检测HSP70蛋白的含量;逆转录聚合酶链反应(RT-PCR)方法检测HSP70mRNA表达水平。结果局灶性脑缺血再灌注24h后脑皮质内HSP70mRNA和HSP70蛋白的表达增加(P0.05)。应用缺血后处理能显著地促进脑缺血再灌注后脑组织HSP70mRNA和HSP70蛋白的表达(P0.05)。结论缺血后处理促进大鼠局灶性脑缺血再灌注皮质内HSP70的表达,这可能是其脑保护作用的部分机制。     

肢体缺血预处理对大鼠缺血再灌注海马HSP70表达的影响

热休克蛋白(heat shock proteins70,HSP70),是一种应激蛋白。研究显示,大鼠大脑中动脉阻断后,HSP70蛋白仅出现在梗死灶周围神经元,即在缺血半影区大量表达。在短暂缺血后死亡的海马CA1区锥体细胞中HSP70蓄积甚少,存活的齿状回颗粒细胞中有明显的HSP70积累。以上表明HSP70可能对脑缺血后神经细胞具有保护作用。我们以前研究结果证实肢体缺血预处理(limb ischemic preconditioning,LIP)可减轻脑缺血再灌注损伤。本实验运用免疫组化技术观察脑缺血再灌注前给予LIP海马HSP70的表达情况,探讨HSP70在LIP抗脑缺血再灌注损伤中的作用。…     

大鼠局灶缺血预处理诱导的脑缺血耐受中热休克蛋白70的表达及其意义

目的　研究局灶脑缺血预处理对热休克蛋白 70 (HSP70 )表达和脑缺血耐受的影响。方法　SD大鼠随机分为 3组 :预缺血组、假手术组及对照组 ,前两组分别在 2小时大脑中动脉缺血 (MCAO)前 3天给予10分钟的预缺血或假手术 ,MCAO后 2 4小时处死 ,对照组给予两次相隔 3天的假手术 ,比较各组梗死体积及HSP70的表达。结果　预缺血组梗死体积较假手术组减少 5 2 5 4 % (P <0 0 1) ,HSP70表达高于假手术组及对照组 (P <0 0 1)。结论　 10分钟大脑中动脉预缺血可有效诱导缺血耐受 ,增加HSP70表达。HSP70表达上调可能是局灶性脑缺血耐受产生的分子机制之一     

脑缺血再灌注后热休克蛋白70、c-fos的表达及柘树制剂的神经保护作用

目的 观察局灶脑缺血再灌注后热休克蛋白（HSP）70、c-fos的表达及其与细胞调亡的关系,探讨柘树制剂对脑缺血后神经细胞损伤的保护作用。方法 采用改良Longa法制作大鼠局灶脑缺血冉灌注模型。柘树制剂预处理组（柘树组）大鼠在实验前灌服柘树制剂2ml每日3次,连用5d。在缺血再灌注不同时点（1h、6h、12h、24h、3d、7d）将大鼠处死取腑,进行HSP70及c-fos免疫组化染色、c-fos mRNA原位杂交、原位末端标记（TUNEL）及HE染色,许对其阳性结果进行半定量分析。结果脑缺血再灌注能诱导HSP70及c-fos的表达。缺血冉灌注6h绀HSP70存缺血侧皮质及基底节开始表达,24h达高峰。缺血再灌注1h组c-fos即有表达,6h达高峰,后逐渐下降。细胞凋亡于缺血再灌注6h最显著。柘树组HSP70及c-fos表达的阳性细胞数均较缺血再灌注组明监增加,两组比较差异均有显著性（均P〈0．01）,而TUNEL阳性细胞数明显减少。结论 HSP70及c=-ros均参与了脑缺血的病理生理过程,柘树制剂对脑缺吡冉灌注损伤有保护作用。     

实验性脑缺血再灌流后不同时程热休克蛋白基因表达的变化

为探讨脑缺血再灌流后热休克蛋白(HSP70)基因表达的变化,采用原位杂交和免疫组化方法检测了脑缺血2h再灌流后不同时程应激蛋白—热休克蛋白(hsp70)mRNA和蛋白表达的变化。结果显示再灌流后早期即可见hsp70mRNA的蛋白表达增加,以18～24h阳性染色最强,HSP70阳性细胞主要分布于缺血周围半暗带区,提示HSP70蛋白表达增加可抵御缺血性脑损伤,对神经元具有保护作用。     

阿司匹林对沙土鼠脑缺血-再灌注损伤后细胞间黏附分子及降钙素基因相关肽表达的影响

目的 探讨阿司匹林对沙土鼠全前脑缺血-再灌注损伤后的脑保护作用及其对细胞间黏附分子及降钙素基因相关肽表达的影响。方法 采用夹闭双侧颈总动脉的方法，制备沙土鼠短暂性全前脑缺血-再灌注模型。63只沙土鼠随机分为假手术组、脑缺血-再灌注组（脑缺血组）和阿司匹林干预组（阿司匹林组）。应用免疫组化SABC法检测脑缺血-再灌注后细胞间黏附分子及降钙素基因相关肽表达水平的变化，以及阿司匹林干预对二者表达的影响。结果 （1）细胞间黏附分子表达的变化：脑缺血-再灌注24h，脑缺血组动物脑组织细胞间黏附分子的表达水平开始增加，3d后明显增强，至7d后仍维持在较高水平，与假手术组相比差异有显著性意义（P〈0．05）。而阿司匹林组动物细胞间黏附分子的表达水平在所有观察时限均明显低于脑缺血组，差异有显著性意义（P〈0．05）。（2）降钙素基因相关肽表达的变化：在脑缺血-再灌注后各时限，脑缺血组动物降钙素基因相关肽的表达均呈弱阳性；而阿司匹林组表达则呈强阳性。结论 脑缺血-再灌注可诱导细胞间黏附分子的表达上调，并抑制降钙素基因相关肽的表达。阿司匹林通过抑制细胞间黏附分子的表达水平和增强降钙素基因相关肽表达而获得较好的脑保护作用。     

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。     

自由基清除剂预处理对大鼠脑缺血再灌注损伤后脑组织细胞凋亡及其相关蛋白表达的影响

目的探讨自由基清除剂依达拉奉预处理对大鼠脑缺血再灌注损伤后神经细胞凋亡及其相关蛋白Bcl-2、Bax、热休克蛋白70(HSP70)表达的影响。方法将45只雄性SD大鼠随机分为假手术组、对照组、依达拉奉预处理组,每组15只。采用线栓法制作大鼠缺血2h再灌注24h模型。预处理组大鼠建模前12h腹腔注射依达拉奉(3mg/kg),对照组给予等容量生理盐水。再灌注24h后断头取脑,应用免疫组织化学法检测Bcl-2、Bax、HSP70蛋白表达,末端脱氧核糖核酸转移酶介导的原位缺口末端标记法检测凋亡细胞。结果依达拉奉预处理组和对照组大鼠缺血周围脑组织中凋亡细胞和Bcl-2、Bax及HSP70阳性细胞数比假手术组均明显增加(P<0.01);与对照组比较,其凋亡细胞和Bax阳性细胞数均明显减少(P<0.01),而Bcl-2和HSP70阳性细胞数明显增加(P<0.01)。结论细胞凋亡在缺血再灌注损伤中起着重要作用;依达拉奉可能通过上调Bcl-2、HSP70蛋白表达、下调Bax蛋白表达减轻大鼠脑缺血再灌注后的细胞凋亡,增加脑缺血再灌注损伤耐受性,从而起到神经保护作用。     

沙土鼠脑缺血后HSP70表达变化研究

目的研究脑缺血后ＨＳＰ７０表达变化。方法采用沙土鼠短暂前脑缺血再灌损伤模型,光镜观察缺血再灌后神经细胞损伤情况,Ｎｏｒｔｈｅｒｎｂｌｏｔ和免疫组化方法分别检测脑缺血后不同时期额叶ＨＳＰ７０ｍＲＮＡ及蛋白表达。结果沙土鼠脑缺血后各期ＨＳＰ７０ｍＲＮＡ表达增加（Ｐ＜０．０５）,而ＨＳＰ７０蛋白仅在再灌后１ｄ有少量表达（Ｐ＜０．０１）。缺血神经细胞在再灌后７ｄ大多出现损伤改变。结论沙土鼠脑缺血后,虽有ＨＳＰ７０转录增加,却存在着ＨＳＰ７０的翻译障碍。ＨＳＰ７０翻译障碍可能是导致神经细胞损伤的重要原因之一。     

Distributions of heat shock protein-70 mRNAs and heat shock cognate protein-70 mRNAs after transient global ischemia in gerbil brain.

Distributions of heat shock protein (HSP)-70 mRNAs and heat shock cognate protein (HSC)-70 mRNAs after 10 min of transient global ischemia were investigated in gerbil forebrain by in situ hybridization using cloned cDNA probes selective for the mRNAs. Expression of HSP70 immunoreactivity was also examined in the same brains. In hippocampal CA1 neuronal cells, in which only a minimal induction of immunoreactive HSP70 protein was found, the strong hybridization for HSP70 mRNA disappeared at around 2 days before the death of CA1 cells became evident. Furthermore, in hippocampal CA3 cells, a striking induction of HSP70 mRNA was sustained even at 2 days along with a prominent accumulation of HSP70 immunoreactivity. In contrast to the case of HSP70 mRNA, HSC70 mRNA was present in most neuronal cells, especially dense in CA3 cells, of the sham brain. A co-induction of HSP70 and HSC70 mRNAs was observed in several cell populations after the reperfusion with a peak at 8 h, although the magnitude of HSC70 mRNA induction was lower than that of HSP70 mRNA, particularly in CA1 cells. The expression of HSC70 mRNA in CA1 cells also disappeared at around 2 days. All the induced signals of HSP70 and HSC70 mRNAs in other cell populations were diminished and returned to the sham level, respectively, by 7 days. These results are the first to show the time courses of distribution of HSP70 and HSC70 mRNAs and the immunoreactive HSP70 protein in the same gerbil brain after ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)     

Different thresholds of HSP70 and HSC70 heat shock mRNA induction in post-ischemic gerbil brain.

Thresholds of induction of heat shock protein (HSP) 70 and heat shock cognate protein (HSC) 70 mRNAs after transient global ischemia in gerbil brain were investigated by in situ hybridization using cloned cDNA probes selective for each mRNA species. In sham control brain, HSP70 mRNA was little present, while HSC70 mRNA was present in most cell populations. A 0.5-min occlusion of bilateral common carotid arteries did not affect the amount of HSP70 and HSC70 mRNAs. The selective induction of HSC70 mRNA was observed in dentate granule cells at 1 h, and in most cells of hippocampus especially dentate gyrus at 3 h after 1 min of ischemia when induction of HSP70 mRNA was not evident in the identical brain. The selective induction diminished by 2 days. However, after 2 min of ischemia, HSP70 and HSC70 mRNAs were induced together in hippocampal cells from 1 h of the reperfusion, and the co-induction prolonged in CA1 cells until 2 days. Body temperatures monitored at rectum increased after the reperfusion with a peak at 30 min. The degree of increase of the body temperature was significantly higher in the case after 2-min ischemia than in the cases after 0.5- and 1-min ischemia. Although HSP70 and HSC70 mRNAs are generally co-induced in stressful conditions, our results suggest the different thresholds of the induction between HSP70 and HSC70 mRNAs after transient brain ischemia. The selective induction of HSC70 mRNA which is not accompanied by the induction of HSP70 mRNA may relate to the differences of the duration of ischemia and the degree of the increase of body temperature after ischemia.     

Up-regulation of endothelial nitric oxide synthase via phosphatidylinositol 3-kinase pathway contributes to ischemic tolerance in the CA1 subfield of gerbil hippocampus.

We here investigated endothelial nitric oxide synthase (eNOS) expression after 10 minutes of forebrain ischemia. Real-time polymerase chain reaction, immunoblots and immunohistochemical studies revealed up-regulation of eNOS expression in the hippocampal CA1 subfield of gerbil. Immunoreactivity of eNOS significantly increased in endothelium but neither in neurons nor astrocytes after 6 to 168 hours of reperfusion. An increased Akt activity preceded the postischemic eNOS up-regulation. Intracerebroventricular injection (i.c.v.) of wortmannin, an inhibitor of phosphatidylinositol 3-kinase (PI-3K), significantly inhibited the increases in both eNOS mRNA and its protein with concomitant inhibition of Akt activation. The significant increase in the eNOS expression was also evident following preconditioning 2-minute ischemia. Both eNOS up-regulation and acquisition of ischemic tolerance observed at 3 days after preconditioning ischemia were significantly inhibited by pretreatment with wortmannin. Administration (i.c.v.) of N-nitro-L-arginine methyl ester, but not 7-nitroindazole, 30 minutes prior to lethal 10-minute ischemia, significantly abolished the acquired tolerance. Intraperitoneal injections of aminoguanidine at immediately after, 24, and 48 hours after preconditioning had no effects on the tolerance. These results suggest that eNOS expression is up-regulated in the endothelium via PI-3K pathways after transient forebrain ischemia, and that preconditioning-induced eNOS expression plays an important role in neuroprotection in the ischemic tolerance.     

Isolation of complementary DNAs for heat shock protein (HSP) 70 and heat shock cognate protein (HSC) 70 genes and the expressions in post-ischaemic gerbil brain

Abstract

A complementary DNA (cDNA) library was constructed with a plasmid vector from cerebral cortices of gerbils at 8 h of reperfusion after 10 min of bilateral common carotid ligation. After the 3rd screening of this cDNA library with a human genomic DNA probe for HSP70 (pH2.3), 4 cDNA clones were isolated (named pGAy pGBy pGD3 and pGE^ respectively). Southern and Northern blot analysisand partial nucleotide sequence analysis indicated that pGA3 and pGE4 were the HSP70 cDNA clones, and that pGB1 and pGD3 were the HSC70 cDNA clones; which selectively recognized HSP70 or HSC70 mRNA, respectively. HSP70 mRNA is present in a very small amount in normal controls, and is greatly induced after the transient ischaemia. HSC70 mRNA is constitutively expressed in a normal gerbil brain, but is still inducible. In situ hybridization study demonstrated that the HSP70 mRNA was present in a very small amount in the hippocampal pyramidal and dentate granule cells in the sham controland that the mRNA was greatly induced in the cells of hippocampus, dentate gyrusmedial habenula, ventral thalamic nuclei, caudate putamen, ventromedial and arcuate hypothalamic nuclei, amygdaloid nuclei and cerebral cortex after 8 h of reperfusion. HSC70 mRNA was present in almost the same areas of sham control and was slightly induced after 8 h of reperfusion. Our results indicate that HSP70 and HSC70 cDNA clones were first isolated from post-ischaemic gerbil brain, and selectively recognize HSP70 or HSC70 mRNA, respectively. A regional difference in the induction of the HSP70 and HSC70 mRNA in post-ischaemic gerbil brain was observed by in situ hybridization. [Neurol Res 1992; 14: 000-000]     

Up-regulation of the peripheral-type benzodiazepine receptor expression and [(3)H]PK11195 binding in gerbil hippocampus after transient forebrain ischemia

In mammalian CNS, the peripheral-type benzodiazepine receptor (PTBR) is localized on the outer mitochondrial membrane within the astrocytes and microglia. The main function of PTBR is to transport cholesterol across the mitochondrial membrane to the site of neurosteroid biosynthesis. The present study evaluated the changes in the PTBR density, gene expression and immunoreactivity in gerbil hippocampus as a function of reperfusion time after transient forebrain ischemia. Between 3 to 7 days of reperfusion, there was a significant increase in the maximal binding site density (B(max)) of the PTBR antagonist [(3)H]PK11195 (by 94-156%; P < 0.01) and PTBR mRNA levels (by 1.8- to 2.9-fold; P < 0.01). At 7 days of reperfusion, in the hippocampal CA1 (the brain region manifesting selective neuronal death), PTBR immunoreactivity increased significantly. Increased PTBR expression after transient forebrain ischemia may lead to increased neurosteroid biosynthesis, and thus may play a role in the ischemic pathophysiology.     

Synergistic induction of HSP40 and HSC70 in the mouse hippocampal neurons after cerebral ischemia and ischemic tolerance in gerbil hippocampus.

An ischemia-induced gene was screened using a differential display technique in mouse transient forebrain ischemia. One of the ischemia-responsive clones was found to encode mouse hsp40. HSP40 has a critical regulatory function in the HSC70 ATPase activity. Expression of hsp40 mRNA was low in the nonischemic mouse hippocampus, but it was significantly upregulated 4 hr after ischemia by Northern blot analysis. In situ hybridization analysis revealed hsp40 mRNA induction in the neuron. HSP40 protein expression was also enhanced in the pyramidal and dentate granular neurons from 2 to 4 days after ischemia. The temporal expression and distribution profile of HSC70 protein was similar to that of HSP40, and both proteins were colocalized in ischemic hippocampal neurons. In the gerbil transient forebrain ischemia model, both HSP40 and HSC70 proteins were expressed strongly in ischemia-resistant CA3 neurons and dentate granule cells 1 day after 5 min ischemia, but were not expressed in vulnerable CA1 neurons. However, both proteins were in parallel expressed in the tolerance-acquired CA1 neurons. Based on the current observation that both HSP40 and HSC70 proteins were synergistically expressed in the ischemia-resistant and tolerance-acquired neurons, cochaperone HSP40 may play a significant role against postischemic neuronal response and lead to cell survival through interaction with simultaneously induced HSC70.     

Changes in immunoreactivity of HSP60 and its neuroprotective effects in the gerbil hippocampal CA1 region induced by transient ischemia

Heat shock proteins act as molecular chaperones and are involved in protein folding, refolding, transport, and translocation. In the present study, we observed changes in heat shock protein 60 (HSP60) immunoreactivity and protein level in the gerbil hippocampal CA1 region after 5 min of transient forebrain ischemia and its neuroprotective effect against ischemic damage. HSP60 immunoreactivity in the CA1 region began to increase in the stratum pyramidale at 30 min after ischemia/reperfusion, and peaked 24 h after ischemia/reperfusion. Thereafter, HSP60 immunoreactivity was decreased in the CA1 region with time. Seven days after ischemia/reperfusion, HSP60 immunoreactivity was increased again in the CA1 region: at this time point after ischemia/reperfusion, HSP60 immunoreactivity was expressed in glial cells in the ischemic CA1 region. HSP60 immunoreactive glial cells were astrocytes containing glial fibrillar acidic protein. In contrast, change in HSP60 immunoreactivity in the ischemic CA2/3 region was not significant compared with that in the ischemic CA1 region. In Western blot study, HSP60 protein level in the CA1 region was increased after ischemia/reperfusion and highest 24 h after ischemia/reperfusion. Animals treated with recombinant adenoviruses expressing Hsp60 (Ad-Hsp60) showed the neuroprotection of CA1 pyramidal neurons from ischemic damage. These results suggest that HSP60 may be associated with delayed neuronal death of CA1 pyramidal neurons after transient ischemia, and the induction of HSP60 protects the neurons from ischemic damage.