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1.
肢体缺血预处理减轻大鼠海马缺血/再灌注损伤   总被引:10,自引:0,他引:10  
目的:探讨肢体缺血预处理(LIP)对大鼠全脑缺血/再灌注损伤的影响.方法: 36只大鼠椎动脉凝闭后随机分为假手术(Control)组、脑缺血组、肢体缺血组、LIP 0 d组(LIP后即刻行脑缺血)、LIP 1 d组(LIP后1 d行脑缺血)和LIP 2 d组(LIP后2 d行脑缺血).重复夹闭大鼠双侧股动脉3次(每次10 min,间隔10 min)作为LIP,夹闭颈总动脉进行全脑缺血8 min后再灌注.硫堇染色观察海马CA1区组织学分级及锥体神经元密度以判断海马损伤程度.结果:脑缺血组海马CA1区锥体神经元损伤严重,与Control组比较,组织学分级明显升高,神经元密度明显降低(P<0.01).LIP 0 d组海马CA1区神经元损伤较脑缺血组明显减轻,组织学分级明显降低,神经元密度明显升高(P<0.01).而LIP 1 d组和LIP 2 d组大鼠海马CA1区锥体细胞缺失较多,仍有明显的组织损伤.结论:LIP可减轻随后立即发生的脑缺血/再灌注损伤,但对间隔1 d后的脑缺血/再灌注损伤无显著对抗作用.  相似文献   

2.
Zhao HG  Li WB  Li QJ  Chen XL  Liu HQ  Feng RF  Ai J 《生理学报》2004,56(3):407-412
探探讨肢体缺血预处理(limb ischemic preconditioning,LIP)对大鼠全脑缺血再灌注后海马CA1区锥体细胞凋亡的影响。46只大鼠椎动脉凝闭后分为假手术组、肢体缺血组、脑缺血组、LIP组。重复夹闭大鼠双侧股动脉3次(每次10min,间隔10min)作为LIP,之后立即夹闭双侧颈总动脉进行全脑缺血8min后再灌注。DNA凝胶电泳、TUNEL和吖啶橙/溴乙锭(AO/EB)双染技术从生化和形态学方面观察海马神经元凋亡的情况。凝胶电泳显示,脑缺血组出现了凋亡特征性DNA梯状条带,而LIP组无上述条带出现。与脑缺血组比较,LIP可明显减少海马CAI区TUNEL阳性神经元数(17.8±5.8vs 69.8±12,P<0.01)。AO/EB染色也显示LIP可明显减少脑缺血再灌注引起的神经元凋亡。以上结果提示,LIP可抑制脑缺血再灌注后海马神经元的凋亡,进而减轻脑缺血再灌注损伤,提供脑保护作用。  相似文献   

3.
目的观察局灶性脑缺血后缺血边缘区海马和皮层NG2细胞的动态表达,探讨其在脑缺血神经损伤与修复过程中所起的作用。方法将大鼠随机分为假手术组(sham)和脑缺血再灌注组,脑缺血再灌注组采用线栓法制备大鼠大脑中动脉阻塞再灌流模型(MCAO),假手术组不插入线栓,采用免疫荧光组织化学法结合共聚焦显微镜成像观察sham组及脑缺血后3d,7d,30d不同时间点缺血边缘区的海马CA1区和皮层区NG2的动态表达情况。结果脑缺血再灌注后缺血边缘区海马和皮层NG2胶质细胞表达增加,缺血后7d最明显。结论脑缺血后缺血边缘区存在NG2细胞的增生和形态变化可能与脑缺血后损伤修复密切相关。  相似文献   

4.
目的 初步观察PPARβ激动剂对大鼠全脑缺血/再灌注损伤的影响.方法 采用双侧颈总动脉夹闭合并低血压的方法建立大鼠全脑缺血/再灌注模型.GW0742(22μg、67μg和200 μg)于建模前30 min脑室注射给予,Morris水迷宫测定大鼠空间学习记忆能力,HE染色观察海马神经元形态变化,生化法检测大鼠海马SOD活性和MDA含量变化.结果 全脑缺血/再灌注大鼠空间学习记忆能力明显下降、海马神经元核固缩,海马SOD活性降低、MDA含量增加;GW0742给予能明显改善全脑缺血再灌注对大鼠空间学习记忆能力的损害和海马神经元损伤,并能明显阻遏全脑缺血再灌注大鼠海马的SOD活性降低、MDA含量增加.结论 PPARβ激动剂对全脑缺血/再灌注大鼠脑损伤有明显保护作用,其神经保护作用机制可能与通过PPARβ激动从而抑制氧化应激反应有关.  相似文献   

5.
目的研究局灶性脑缺血再灌注损伤中iNOS在不同脑区的表达.方法用改良的血管内栓线技术制造大鼠局灶性脑缺血与再灌注模型,应用免疫组织化学技术检测脑组织中的iNOS的表达.结果 (1)脑缺血再灌注损伤24h后,缺血组缺血侧大脑皮层、海马CA1区、CA3区神经元iNOS的表达显著增强,与正常对照组比较有显著性差异(P<0.05);(2)脑缺血再灌注损伤24h后,缺血组对照侧大脑皮层、海马CA1区、CA3区神经元iNOS的表达也明显增强,与正常对照组比较有显著性差异(P<0.05);(3) 与对照侧比较,脑缺血再灌注大鼠缺血侧皮质的iNOS表达显著增强(P<0.05),而海马CA1区、CA3区缺血侧的iNOS表达与对照侧相比无显著性差异(P>0.05).结论局灶性脑缺血再灌注损伤后,缺血侧皮层和海马iNOS表达显著升高,未缺血脑区(对照侧)iNOS反应性也较对照组者升高.  相似文献   

6.
Zhao HG  Li WB  Sun XC  Li QJ  Ai J  Li DL 《中国应用生理学杂志》2007,23(1):19-23,I0002
目的:探讨神经途径在肢体缺血预处理(limbi schemic preconditioning,LIP)抗脑缺血/再灌注损伤中的作用。方法:脑缺血采用四血管闭塞模型,重复短暂夹闭放松大鼠双侧股动脉3次作为LIP。将凝闭椎动脉的大鼠随机分为sham组、脑缺血组、股神经切断+脑缺血组、LIP+脑缺血组、股神经切断+LIP+脑缺血组。于Sham手术和脑缺血后7d处死大鼠,硫堇染色观察海马CA1区锥体神经元迟发性死亡的变化。于Sham手术和脑缺血后6h心脏灌注固定大鼠,免疫组化法测定海马CAI区c-Fos表达的变化。结果:硫堇染色结果显示,与sham组比较。脑缺血组和股神经切断+脑缺血组大鼠海马CAI区均有明显组织损伤。LIP+脑缺血组CAI区无明显细胞缺失,神经元密度明显高于脑缺血组(P〈0.01)。而股神经切断+LIP+脑缺血组大鼠海马CA1区明显损伤,锥体细胞缺失较多,与LIP+脑缺血组组比较,神经元密度显著降低(P〈O.01),提示LIP前切断双侧股神经取消了LIP抗脑缺血/再灌注损伤作用。c—Fos免疫组化染色结果显示,Sham组海马CAI区未见明显的c-Fos蛋白表达。脑缺血组海马CAI区偶见c—Fm的阳性表达。LIP+脑缺血组c—Fos表达增强,数量增加,与Sham组和脑缺血组比较。c-Fos阳性细胞数和光密度均明显升高(P〈0.01)。而股神经切断+LIP+脑缺血组c-Fos表达明显减少,仅见少量弱阳性e-Fos表达。结论:LIP可通过神经途径发挥抗脑缺血/再灌注损伤作用,而LIP诱导c—Fos表达增加可能是LIP诱导脑缺血耐受神经途径的一个环节。  相似文献   

7.
目的:观测缺血/再灌注小鼠海马组织环磷酸腺苷(cAMP)和腺苷环化酶(AC)mRNA水平,探讨缺血/再灌注发病的分子生物学机制.方法:通过双侧颈总动脉线结、连续3次缺血-再灌注,制作缺血/再灌注动物模型,并设立假手术组;术后29 d、30 d分别测试学习和记忆成绩;应用放射免疫法检测小鼠海马组织cAMP水平,应用原位杂交技术检测ACmRNA水平.结果:与假手术组比较,模型组学习和记忆成绩均降低(P<0.05),且海马组织cAMP水平也降低(P<0.05),海马CA1区AC mRNA阳性神经元面密度明显降低(P<0.05).结论:海马组织cAMP和AC mRNA水平降低可能参与了缺血/再灌注后学习和记忆障碍的分子生物学发病机制.  相似文献   

8.
异丙酚对全脑缺血/再灌注大鼠海马iNOS表达的影响   总被引:1,自引:0,他引:1  
目的观察异丙酚对全脑缺血/再灌注大鼠海马神经元诱导型一氧化氮合酶(iNOS)表达的影响,探讨异丙酚对迟发性脑神经元损伤保护作用机制。方法采用Pulsinelli-Brierley四血管阻断法制备全脑缺血模型。全脑缺血20min再灌注24h后断头取脑,采用Western blot方法检测大鼠海马iNOS的蛋白表达。结果与缺血/再灌注组相比较,异丙酚处理组大鼠海马iNOS蛋白表达明显降低,存活的神经元数目明显增加,统计结果差异均有显著性(P<0.05或0.01)。结论异丙酚通过抑制iNOS蛋白表达对大鼠脑迟发性神经元损伤起保护作用。  相似文献   

9.
已有研究表明在脑缺血期间及再灌流后早期,海马CA1锥体神经元细胞内钙浓度明显升高,这一钙超载被认为是缺血性脑损伤的重要机制之一.电压依赖性钙通道是介导正常CA1神经元钙内流的主要途径.实验观察了脑缺血再灌流后早期海马CA1锥体神经元电压依赖性L型钙通道的变化.以改良的四血管闭塞法制作大鼠 15min前脑缺血模型,在急性分离的海马CA1神经元上,采用膜片钳细胞贴附式记录L型电压依赖性钙通道电流.脑缺血后CA1神经元L型钙通道的总体平均电流明显增大,这是由于通道的开放概率增加所致.进一步分析单通道动力学显示,脑缺血后通道的开放时间变长,通道的开放频率增大.研究结果提示L型钙通道功能活动增强可能参与了缺血后海马CA1锥体神经元的细胞内钙浓度升高  相似文献   

10.
已有研究表明在脑缺血期间及再灌流后早期,海马CA1锥体神经元细胞内钙浓度明显升高,这一钙超载被认为是缺血性脑损伤的重要机制之一.电压依赖性钙通道是介导正常CA1神经元钙内流的主要途径.实验观察了脑缺血再灌流后早期海马CA1锥体神经元电压依赖性L型钙通道的变化.以改良的四血管闭塞法制作大鼠15 min前脑缺血模型,在急性分离的海马CA1神经元上,采用膜片钳细胞贴附式记录L型电压依赖性钙通道电流.脑缺血后CA1神经元L型钙通道的总体平均电流明显增大,这是由于通道的开放概率增加所致.进一步分析单通道动力学显示,脑缺血后通道的开放时间变长,通道的开放频率增大.研究结果提示L型钙通道功能活动增强可能参与了缺血后海马CA1锥体神经元的细胞内钙浓度升高.  相似文献   

11.
Wang RM  Yang F  Zhang YX 《Life sciences》2006,79(19):1839-1846
Accumulating evidence implicates activation (phosphorylation) of mitogen-activated protein kinases (MAPK) during nonlethal ischemic preconditioning in the protection of hippocampal CA1 neuron against subsequent ischemic events. In this paper, we undertook to identify the role of extracellular signal regulated kinase (ERK) 5 in cerebral ischemic preconditioning (CIP). Three minutes of ischemia was induced as preconditioning stimulus. Three days later, 6 min of ischemia was induced. The levels of ERK5 protein expression and its activation were detected with or without the CIP in hippocampal CA1 and the dentate gyrus (DG) regions. Our results showed that ERK5 was activated selectively in hippocampal CA1 region with, but not without, the ischemic preconditioning. Notably, during the later phase of reperfusion, the rise in ERK5 activation was strong and persistent with a peak occurring at the third day. The activation peak was effectively prevented and ERK5 protein expression was significantly decreased by intracerebroventricular infusion of ERK5 antisense oligonucleotide (every 24 h for 3 days before the preconditioning), but not by sense oligonucleotide or vehicle. Subsequently, the CA1 neuronal loss was largely elevated. Moreover, both MK801 (10 microM), an antagonist of NMDA receptor, and EGTA (100 mM, but neither 50 nor 150 mM), an extracellular Ca2+ chelator, not only effectively inhibited the ERK5 activation but also markedly abolished CIP-induced survival of the CA1 neurons. These results suggested that activation of the ERK5 pathway by CIP was at least partly dependent on moderate Ca2+ influx via NMDA receptor, which might contribute to ischemic tolerance in hippocampal CA1 region of rats.  相似文献   

12.
Exogenously administered adenosine agonist will protect myocardium against infarction during ischemia. However, long-term exposure to adenosine agonists is associated with loss of this protection. To determine why this protection is lost, isolated, perfused rabbit hearts were studied after administration of R(-)-N6-(2-phenylisopropyl)adenosine (PIA), 0.25 mg/h IP, for 3-4 days to intact animals. All hearts experienced 30 min of regional ischemia and 120 min of reperfusion. Control groups 1 and 2 were untreated. In group 1 this ischemia/reperfusion was the only intervention, whereas group 2 hearts were preconditioned with a cycle of 5 min global ischemia/10 min reperfusion preceding the 30 min regional ischemia. Groups 3-5 had been chronically exposed to PIA. Group 3 hearts had 1 preconditioning ischemia/reperfusion cycle before the prolonged ischemia. Group 4 received a 5 min infusion of 0.1 mol/L phenylephrine in lieu of global ischemia, whereas group 5 was instead treated with 1 mol/L carbachol. Infarct size averaged 32% of the risk zone in group 1, whereas ischemic preconditioning limited infarction to 8.2 in group 2. Prolonged exposure of group 3 hearts to PIA resulted in the inability of preconditioning with 5 min global ischemia to protect (28.7 ± 4.4% infarction). However, protection was restored by either phenylephrine, an agonist of 1-adrenergic receptors which couple to Gq and stimulate PKC, or carbachol, an agonist of M2-muscarinic receptors which couple instead to Gi as do adenosine A1 receptors (5.2 ± 1.7% and 9.2 ± 2.1% infarction, resp.). Therefore, cross tolerance to ischemic preconditioning develops after chronic PIA infusion. Since both the Gi and the PKC components of the preconditioning pathway were shown to be intact, tolerance must have been related to downregulation or desensitization of the A1 adenosine receptor.  相似文献   

13.
Glial glutamate transporter-1 (GLT-1) is the predominant subtype of glutamate transporters which are responsible for the homeostasis of extracellular glutamate. Our previous studies have shown that up-regulation in GLT-1 protein expression matches brain ischemic tolerance induced by cerebral ischemic preconditioning (CIP). To specify the role of functional changes of GLT-1 in the induction of brain ischemic tolerance by CIP, the present study was undertaken to examine changes in the binding properties of GLT-1 (including maximum binding and affinity for glutamate) and in GLT-1 mediated glutamate uptake, using L-3H-glutamate assay in the rat hippocampus. The results indicated that CIP was able to increase the maximum binding and affinity, and uptake of GLT-1 for glutamate in hippocampal CA1 subfield either with or without the presence of the subsequent severe brain ischemic insult. Simultaneously, accompanied with the above changes, CIP significantly reduced the delayed neuronal death (DND) in this region induced by lethal global cerebral ischemia. It could be concluded that up-regulation in the maximum binding and affinity and glutamate uptake of GLT-1 contributed to the neuronal protection of CIP against global cerebral ischemic insult.  相似文献   

14.
Here we examined the effects of ischemia preconditioning and ketamine, an NMDA receptor antagonist, on the activation and its nucleus translocation of ERK5 in hippocampal CA1 region. Our results showed ERK5 was not activated in rat hippocampus CA1 region. But in cytosol extracts preconditioned with 3 min of sublethal ischaemia, ERK5 activation was enhanced significantly, with two peaks occurring at 3 hr and 3 days, respectively. This activation returned to base level 3 days later. The results lead us to conclude that preconditioning increased the activations of ERK5 during reperfusion after lethal ischemia through NMDA receptor. Preconditioning increased the activation and nucleus translocation of ERK5 during reperfusion after lethal ischemia through the NMDA receptor. These findings might provide some clues to understanding the mechanism underlying ischemia tolerance and to finding clinical therapies for stroke using the endogenous neuroprotection.  相似文献   

15.
Global cerebral ischemia induced to Mongolian gerbils by ligation of common carotid arteries (CCAs) is known to result in injury to the hippocampal CA1 region. In this study, we examined whether neuronal injury can be depicted by measuring levels of mRNA encoding inositol 1,4,5-trisphosphate receptor type 1 (IP3R1), neuron specific enolase (NSE) and -actin and whether these measurements can be use to assess ischemic tolerance. Gerbils were subjected either to cerebral ischemia induced by ligation of both CCAs for 5 min, or to an ischemic tolerance paradigm in which a 2 min ischemic preconditioning was performed 24 hr prior to the 5 min ischemia. At 48 hr after the 5 min ischemic insult, significant decreases in mRNA levels for IP3R1 (26%), NSE (38%) and -actin (50%) could be observed in the hippocampal CA1 region. Although levels of mRNA in the preconditioning group were decreased as compared to the sham control, the levels were significantly higher than those in the ischemic group. These results indicate the feasibility of using mRNA measurement as a parameter to assess cerebral ischemic damage. In addition, based on the differences in the decline in mRNA levels between the ischemia group and the preconditioned ischemia group, it can be concluded that this ischemic tolerance paradigm could offer partial protection (around 45%) against the injury due to the 5 min cerebral ischemic insult.  相似文献   

16.
Ischemic preconditioning (IPC) represents the phenomenon of CNC adaptation, which results in increased tolerance of CNS to lethal ischemia. Brain ischemia/reperfusion (IRI) initiates a catastrophic cascade in which many subcellular organelles play an important role. The Golgi apparatus, which is a part of secretory pathways (SP), represents the Ca2+ store and regulates secretion of proteins for growth/reorganization of neuronal circuit by secretory Ca2+ATPases (SPCA1). The purpose of this study is to evaluate the effect of IRI and preconditioning on SPCA1 gene expression and oxidative damage after 4-vessel occlusion for 15 min and after being exposed to different reperfusion periods. Rats were preconditioned by 5 min of sub-lethal ischemia and 2 days later, 15 min of lethal ischemia was induced. Our experiments conclusively showed IRI-induced depression of SPCA activity and lipo- and protein oxidation in rat hippocampal membranes. IRI also activates the induction of SPCA1 gene expression in later reperfusion periods. IPC partially suppresses lipo- and protein oxidation in hippocampal membranes and leads to partiall rovery of the ischemic-induced depression of SPCA activity. In addition, IPC initiates earlier cellular response to the injury by the significant elevation of mRNA expression to 142% comparing to 1 h of corresponding reperfusion and to 11% comparing to 24 h of corresponding reperfusion, respectively. Similar patterns were observed on the translational level by Western blot analysis. Our results indicate the specific SPCA1 expression pattern in ischemic hippocampus. It also shows that the SPCA expression and the post-translational changes induced by ischemia are modulated by the IPC. This might serve to understand the molecular mechanisms involved in the structural integrity and function of the SP after ischemic challenge. It also suggests that there is a correlation of SPCA function with the role of SP in the response to pre-ischemic challenge.  相似文献   

17.
Ischemic tolerance, the phenomenon where a sublethal ischemic preconditioning protects the brain against a subsequent lethal ischemia, has been widely studied. Studies have been done on cerebral blood flow levels prior to the lethal ischemia, but the hemodynamic pattern after global ischemia with ischemic preconditioning has not been reported. Sequential changes in regional cerebral blood flow (rCBF) in gerbil hippocampus after 5 min global ischemia with or without 2 min ischemic preconditioning were studied to determine if ischemic preconditioning affects rCBF. Four different treatments were given: (1) sham-operated, (2) 2 min ischemia, (3) non-preconditioned, and (4) preconditioned. Groups (1) and (2) (both groups n = 5) were given a 24-h recovery period and the rCBF was measured for baseline values. 24 h after sham-operation (3) and 2 min ischemia (4), gerbils were subjected to 5 min ischemia followed by 1 h, 6 h, 1-day or 7-day reperfusion periods (all groups n = 5). Although no regional difference was observed in the recovery pattern of rCBF, the values of rCBF were significantly higher in the preconditioned group throughout whole brain regions including hippocampus. These results indicate that ischemic preconditioning facilitated the recovery of rCBF after 5 min global ischemia. It needs further study to determine whether the protecting effects of preconditioning relate to the early recovery of rCBF or not. However, our results could be interpreted that the early recovery of rCBF may lead to benefits for cell survival in the CA1 neuron, probably facilitating other protecting mechanisms.  相似文献   

18.
Ischemic preconditioning (IPC), comprising exposure to sub-lethal short term ischemic events, has been shown to exert adaptive responses in many organs including the brain, thus guarding against exacerbations of ischemia reperfusion (IR). However, the mechanisms involved in the early phase of such a protection remain elusive; hence, the present study aimed to investigate the modulatory effect of preconditioning against IR induced injury on infarct size, free radicals, inflammatory/anti-inflammatory markers, caspase-3 and heat shock protein (HSP)70 in the rat hippocampus. To this end, male Wistar rats were divided into 3 groups, (1) sham operated (SO) control; (2) IPC, animals were subject to 3 episodes of ischemia (5 min) followed by reperfusion (10 min), afterwards rats underwent ischemia (15 min) followed by reperfusion (60 min); (3) IR animals were subjected to 15 min global ischemia followed by 60 min reperfusion. IR produced cerebral infarction accompanied by an imbalance in the hippocampal redox status, neutrophil infiltration, elevation in tumor necrosis factor (TNF)-α and prostaglandin (PG)E2, besides reduction in interleukin (IL)-10 and nitric oxide (NO) levels. IPC reverted all changes except for PGE2; however, neither HSP70 nor caspase-3 expression was altered following IR or IPC. The current study points thus towards the activation of the antioxidant system, anti-inflammatory pathway, as well as NO in the early phase of preconditioning protection.  相似文献   

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