银杏内酯B和低氧预适应对小鼠急性缺氧损伤的保护作用

目的：通过观察缺氧预适应和银杏内酯B预处理对小鼠急性缺氧的影响,了解银杏内酯B的脑保护作用。方法：采用小鼠常压缺氧模型,观察小鼠的行为学并记录各组小鼠的最后死亡时间,脑组织含水量,用RT-PCR、Western blot分别检测各组小鼠皮层组织中RTP801mRNA表达和EPO蛋白表达。结果：银杏内酯B和低氧预适应均能明显延长常压缺氧小鼠的存活时间,降低脑水肿程度,并且银杏内酯组和低氧预适应组RTP801mRNA表达和EPO的表达均明显增加。结论：银杏内酯B与低氧预适应具有相类似的对抗小鼠急性低氧的作用,其脑保护作用与上调RTPS01mRNA和EPO蛋白的表达有关。     

芍药甘草汤及其活性成分的脑保护作用机制研究概述

芍药甘草汤由东汉张仲景创立,仅有芍药和甘草两味药物组成,具有调和肝脾,缓急止痛的功效,是经典的止痛方剂,临床主要用于血虚津伤所导致的各种内脏疼痛,腓肠肌痉挛的治疗中。已经展开的基础研究主要集中解痉、止痛和抗炎方面的机理研究。近年逐步认识到芍药甘草汤及其活性成分在神经保护领域的作用,在脑卒中、帕金森病、阿尔海默氏症、癫痫等中枢神经系统疾病基础研究中,取得成果。文章研读近年来国内外相关文献,分别从芍药、甘草的活性成份以及芍药甘草汤方剂在脑保护领域进行的基础研究的进展做一综述,显示了芍药甘草汤及其活性成分可以抑制脑组织免疫炎症反应、抑制氧化反应、抗谷氨酸毒性,改善脑血流、抗细胞凋亡和保护神经元的作用,阐述了芍药甘草汤的多途径、多靶点的药理优势及在脑保护领域的应用前景。     

缺血预适应对小鼠脑缺血再灌注损伤模型血脑屏障的保护作用及机制

目的:通过研究缺血预适应对小鼠脑缺血再灌注损伤血脑屏障通透性的影响,探讨缺血预适应的脑保护作用及相关分子机制。方法:取清洁健康成年小鼠72只,随机分为脑缺血预适应组(brain ischemic precondition,BIP),脑缺血再灌注组(middle cerebral artery occlusion and reperfusion,MCAO/R)和假手术组(sham group),每组均24只,采用zealonga线栓法栓塞小鼠大脑中动脉建立BIP模型和MCAO/R模型,通过氯化三苯基四氮唑(triphenyl tetrazolium chloride,TTC)染色计算脑梗死面积,改良神经功能缺损评分(modified neurological severity scores,m NSS)对脑缺血再灌注神经损伤程度进行评估,测干-湿重法以及伊文氏蓝(Evans blue,EB)示踪结合脑组织EB定量法评价血脑屏障(blood brain barrier,BBB)的损伤程度,采用免疫组化法检测各组脑组织低氧诱导因子-1α(HIF-1α)和血管内皮生长因子(VEGF)的表达。结果:与MCAO组相比,BIP组显著降低缺血再灌注后m NSS评分,缩小了梗死面积并减轻脑水肿,有效的保护BBB功能,BIP组再灌注24 h时脑梗死灶周围皮质区HIF-1α及VEGF的表达均明显上调,差异有统计学意义(P0.05)。结论:BIP对小鼠脑缺血再灌注损伤模型BBB有一定的保护作用,其机制可能与其诱导HIF-1α及VEGF的表达上调有关。     

缺氧预适应研究的进展与展望

缺氧预适应这一生物进化上的内源性细胞保护机制,可被机体、器官、组织和细胞的重复缺氧暴露所激发。缺氧预适应的效应已由对重复缺氧局部／原位器官组织的保护（局部／原位缺氧预适应）发展到既保护远隔的各种异位器官组织（远程／异位缺氧预适应）又抗御其它种种非缺氧性应激（交叉／多能缺氧预适应）。在现有进展的基础上,缺氧预适应研究以及其可操作性和可应用性将有更大的发展空间。     

脑缺血预适应大鼠脑内JNK磷酸化水平和蛋白表达量的改变

脑缺血预适应是神经细胞对抗缺血刺激产生的一种内源性保护机制，即通过事先适度的缺血预刺激处理后，脑组织对随后的致死性缺血具有一定的防御和保护效应。近年来，对于参与这一内源性保护机制的细胞信号传导系统的研究引起人们的广泛关注。[第一段]     

脑益康药物血清对谷氨酸诱导海马神经元损伤的保护作用

目的:探讨脑益康药物血清对谷氨酸(Glu)诱导的海马神经元损伤的保护作用。方法:大鼠海马神经元培养后,采用形态学观察、MTT法及DAPI染色法检测脑益康药物血清对Glu损伤细胞活力的影响,采用RT-PCR和免疫组化方法检测脑益康药物血清对Glu损伤细胞PTEN表达的影响。结果:脑益康药物血清可明显提高Glu损伤的海马神经元的细胞活力,减少PTEN的表达。结论:脑益康药物血清对Glu诱导的海马神经元损伤有保护作用,其机制可能与减少PTEN表达,抑制神经元凋亡有关。     

低氧预适应小鼠皮层Bcl-2和Caspase-3的表达变化

本文旨在探讨小鼠皮层Bcl-2和Caspase-3在低氧预适应脑保护中的作用.将Bib/c近交系小鼠随机分为对照组、低氧组和低氧预适应组,用免疫荧光和激光共聚焦显微镜等技术测定皮层顶叶Bcl-2和Caspase-3表达荧光强度和阳性细胞计数.结果显示,低氧组和低氧预适应组Bcl-2表达均显著高于对照组,低氧预适应组又显著高于低氧组.低氧组和低氧预适应组Caspase-3表达均显著高于对照组,但低氧预适应组显著低于低氧组.结果表明,低氧预适应过程中,小鼠皮层脑区通过Bcl-2高表达和Caspase-3低表达抵御皮层细胞凋亡,从而参与脑保护机制.     

脑类器官技术的发展与应用

脑类器官是由多能干细胞在三维培养条件下,通过添加神经发育相关调控信号而分化产生的与脑的细胞组成、解剖结构相似,并可以体现出类脑的发育进程及生理、病理和药理等特征的细胞培养物,是迄今在体外研究人脑发育与相关疾病,并开展药物筛选的良好模型。伴随着技术发展,脑类器官在研究脑发育与疾病,不同脑区以及脑与其他组织/器官间的相互作用,脑进化等多个方面发挥重要作用。该文综述了脑类器官的发展历程,及其在探索脑发育、疾病模拟和药物筛选等方面的进展。     

ATP敏感的钾通道与预适应心肌保护作用

缺血、药物等多种因素产生的预适应现象都具有显著的心肌保护作用。ATP敏感的钾通道是介导预适应保护作用的重要环节。目前多数研究结果表明是线粒体而非质膜ATP敏感的钾通道介导了预适应的保护作用,但它是否为此过程的最终效应器尚有待更多更深入的研究,未来线粒体ATP敏感钾通道的克隆和调控机制的揭示,将是从根本上解决这一问题的关键。     

低氧预适应对离体星形胶质细胞低氧耐受性的影响

目的：研究低氧预适应对体外培养的星形胶质细胞低氧耐受性的影响。方法：体外培养的鼠脑星形胶质细胞,随机分为对照组（control,C组）,低氧损伤组（hypoxia,H组）,低氧预适应组（hypoxic preconditioning,HP组）,通过检测细胞MTT代谢变化、凋亡发生和形态学观察探讨低氧预适应对星型胶质细胞低氧损伤的保护作用;免疫细胞化学方法分析Bcl-2和Bax的表达差异。结果：与低氧组相比,HP48、HP72组MTT代谢活性较高。免疫细胞化学结果提示低氧预适应组Bcl-2表达高于低氧损伤组,低氧预适应组Bax表达低于低氧损伤组。结论：低氧预适应对大鼠星形胶质细胞低氧损伤有保护作用,可能与Bax表达受抑,维持Bcl-2表达有关,通过对抗凋亡程序的发展产生保护作用。     

The protective effect of ischemic preconditioning on rat testis

Background  

It has been demonstrated that brief episodes of sublethal ischemia-reperfusion, so-called ischemic preconditioning, provide powerful tissue protection in different tissues such as heart, brain, skeletal muscle, lung, liver, intestine, kidney, retina, and endothelial cells. Although a recent study has claimed that there are no protective effects of ischemic preconditioning in rat testis, the protective effects of ischemic preconditioning on testicular tissue have not been investigated adequately. The present study was thus planned to investigate whether ischemic preconditioning has a protective effect on testicular tissue.     

Effects of hypoxic preconditioning on memory evaluated using the T-maze behavior test

Perioperative brain ischemia and stroke are leading causes of morbidity and mortality. Brief hypoxic preconditioning is known to have protective effects against hypoxic-ischemic insult in the brain. Current studies on the neuroprotective effects of ischemic preconditioning are based on histologic findings and biomarker changes. However, studies regarding effects on memory are rare. To precondition zebrafish to hypoxia, they were exposed to a dissolved oxygen (DO) concentration of 1.0?±?0.5?mg/L in water for 30?s. The hypoxic zebrafish were then exposed to 1.0?±?0.5?mg/L DO until the third stage of hypoxia, for 10 min?±?30?s. Zebrafish were assessed for memory retention after the hypoxic event. Learning and memory were tested using the T-maze, which evaluates memory based on whether or not zebrafish moves to the correct target compartment. In the hypoxic preconditioning group, infarct size was reduced compared with the hypoxic-only treated zebrafish group; memory was maintained to a degree similar to that in the hypoxia-untreated group. The hypoxic-only group showed significant memory impairments. In this study, we used a hypoxic zebrafish model and assessed the effects of ischemic preconditioning not only on histological damages but also on brain function, especially memory. This study demonstrated that a brief hypoxic event has protective effects in hypoxic brain damage and helped maintain memory in zebrafish. In addition, our findings suggest that the zebrafish model is useful in rapidly assessing the effects of ischemic preconditioning on memory.     

Chemical preconditioning effect of 3-nitropropionic acid in anesthetized rat heart

Short ischemic episodes increase tolerance against subsequent severe ischemia in the heart. Nitropropionate (3-NP), an irreversible inhibitor of succinic dehydrogenase of the mitochondrial complex II, was shown to induce protective effect against ischemic brain injury. The aim of this study was to investigate the possible protective effect of 3-NP on regional ischemia in preconditioned rat heart in vivo. Hearts were assigned into three groups: first, in order to induce ischemic preconditioning (IP) 5 min ischemia separated by 10 min reperfusion protocol was used; second, non-preconditioned group was used as control; and third, 3-NP (20 mg/kg, i.p.) was injected 3 h before the surgical procedure in order to induce chemical preconditioning. In all these groups, 30 min regional ischemia was followed by 60 min reperfusion. Infarct size, bax expression, number of ventricular ectopic beats (VEB), duration of ventricular tachycardia (VT) and ventricular fibrillation (VF) were significantly decreased in ischemic preconditioning and 3-NP pretreatment groups, whereas bcl-2 values were not markedly changed in these groups during occlusion period. These results showed that in the anesthetized rat heart 3-NP induced chemical preconditioning by decreasing infarct size, number of VEB, duration of VT and VF. Protective effect is associated with via decreased production of bax protein expression.     

预处理保护作用的普遍性及其机理探讨

本工作分别在大鼠的多种器官上观察到缺血预处理（ＰＣ）对缺血／再灌注损伤的保护作用具有器官普遍性,其对血管床的保护是其器官保护的机制之一;在体外培养的乳鼠（兔）心肌细胞及大鼠（兔）胸主动脉血管平滑肌细胞等多种细胞等多种细胞上观察到蛋白激酶Ｃ（ＰＫＣ）激活及ＰＫＣ介导的蛋白磷酸化增强是ＰＣ细胞保护的共有环节。碱性成纤维细胞生长因子可以模拟ＰＣ的细胞保护作用,提示药物预处理对于防治缺血有关的疾病可能上人     

Role of the mitochondrial ATP-sensitive K+ channels in cardioprotection

The mitochondrial ATP-sensitive K(+) (mitoK(ATP)) channel was discovered more than a decade ago. Since then, several pharmacological studies have identified agents that target this channel some of which selectively target mitoK(ATP). These and other studies have also suggested that mitoK(ATP) plays a key role in the process of ischemic preconditioning (IPC) and prevention of apoptosis. The mechanism by which mitoK(ATP) exerts its protective effects is unclear, however, changes in mitochondrial Ca(2+) uptake and levels of reactive oxygen species, and mitochondrial matrix swelling are believed to be involved. Despite major advances, several important issues regarding mitoK(ATP) remain unanswered. These questions include, but are not limited to: the molecular structure of mitoK(ATP), the downstream and upstream mechanisms that leads to IPC and cell death, and the pharmacological profile of the channel. This review attempts to provide an up-to-date overview of the role of mitoK(ATP) in cardioprotection.     

Intermittent Hypobaric Hypoxia Preconditioning Induced Brain Ischemic Tolerance by Up-Regulating Glial Glutamate Transporter-1 in Rats

Several studies showed that the up-regulation of glial glutamate transporter-1 (GLT-1) participates in the acquisition of brain ischemic tolerance induced by cerebral ischemic preconditioning or ceftriaxone pretreatment in rats. To explore whether GLT-1 plays a role in the acquisition of brain ischemic tolerance induced by intermittent hypobaric hypoxia (IH) preconditioning (mimicking 5,000?m high-altitude, 6?h per day, once daily for 28?days), immunohistochemistry and western blot were used to observe the changes in the expression of GLT-1 protein in hippocampal CA1 subfield during the induction of brain ischemic tolerance by IH preconditioning, and the effect of dihydrokainate (DHK), an inhibitor of GLT-1, on the acquisition of brain ischemic tolerance in rats. The basal expression of GLT-1 protein in hippocampal CA1 subfield was significantly up-regulated by IH preconditioning, and at the same time astrocytes were activated by IH preconditioning, which appeared normal soma and aplenty slender processes. The GLT-1 expression was decreased at 7?days after 8-min global brain ischemia. When the rats were pretreated with the IH preconditioning before the global brain ischemia, the down-regulation of GLT-1 protein was prevented clearly. Neuropathological evaluation by thionin staining showed that 200?nmol DHK blocked the protective role of IH preconditioning against delayed neuronal death induced normally by 8-min global brain ischemia. Taken together, the up-regulation of GLT-1 protein participates in the acquisition of brain ischemic tolerance induced by IH preconditioning in rats.     

Ischemic preconditioning: tolerance to hepatic ischemia-reperfusion injury

Hepatic ischemia-reperfusion (I/R) injury still remains an unresolved problem in both liver resectional surgery and liver transplantation and may be responsible for liver failure, lung injury and death. The current review summarizes the findings reported to date on the effectiveness of ischemic preconditioning against liver and lung damage associated with hepatic I/R injury and the underlying protective mechanisms. The effect of ischemic preconditioning on the mechanisms potentially involved in hepatic I/R injury, including alterations in energy metabolism, neutrophil accumulation, microcirculatory disturbances, formation of proinflammatory mediators, such as endothelin and tumor necrosis factor-alpha, and reactive oxygen species generation have been evaluated. In this review, we address the role of preconditioning in the increased vulnerability of fatty livers to hepatic I/R injury. The effectiveness of ischemic preconditioning versus pharmacological strategies that could simulate the benefits of liver preconditioning has been also discussed.     

K(ATP) channel activation reduces the severity of postresuscitation myocardial dysfunction

Postresuscitation myocardial dysfunction has been recognized as a leading cause of the high postresuscitation mortality rate. We investigated the effects of ischemic preconditioning and activation of ATP-sensitive K(+) (K(ATP)) channels on postresuscitation myocardial function. Ventricular fibrillation (VF) was induced in 25 Sprague-Dawley rats. Cardiopulmonary resuscitation (CPR), including mechanical ventilation and precordial compression, was initiated after 4 min of untreated VF. Defibrillation was attempted after 6 min of CPR. The animals were randomized to five groups treated with 1) ischemic preconditioning, 2) K(ATP) channel opener, 3) ischemic preconditioning with K(ATP) channel blocker administered 1 min after VF, 4) K(ATP) channel blocker administered 45 min before induction of ischemic preconditioning, and 5) placebo. Postresuscitation myocardial function, as measured by the rate of left ventricular pressure increase at 40 mmHg, the rate of left ventricular decline, cardiac index, and duration of survival, was significantly improved in both preconditioned and K(ATP) channel opener-treated animals. K(ATP) channel blocker administered 45 min before induction of ischemic preconditioning completely abolished the myocardial protective effects of preconditioning. We conclude that ischemic preconditioning significantly improved post-CPR myocardial function and survival. These results also provide evidence that the myocardial protective effects of ischemic preconditioning are mediated by K(ATP) channel activation.     

How to use the paradigm of ischemic preconditioning to protect the heart?

Ischemic preconditioning affords the most powerful protection to a heart submitted to a prolonged ischemia-reperfusion. During the past decade, a huge amount of work allowed to better understand the features of this protective effect as well as the molecular mechanisms. Ischemic preconditioning reduces infarct size and improves functional recovery; its effects on arrhythmias remain debated. Triggering of the protection involves cell surface receptors that activate pro-survival pathways including protein kinase C, PI3-kinase, possibly Akt and ERK1/2, whose downstream targets remain to be determined. Much attention has been recently focused on the role of mitochondrial K(+)ATP channels and the permeability transition pore that seem to play a major role in the progression toward irreversible cellular injury. Based on these experimental studies attempts have been made to transfer preconditioning from bench to bedside. Human experimental models of ischemic preconditioning have been set up, including cardiac surgery, coronary angioplasty or treadmill exercise, to perform pathophysiological studies. Yet, protecting the heart of CAD (coronary artery disease) patients requires a pharmacological approach. The IONA trial has been an example of the clinical utility of preconditioning. It helped to demonstrate that chronic administration of nicorandil, a K(+)ATP opener that mimics ischemic preconditioning in experimental preparations, improves the cardiovascular prognosis in CAD patients. Recent experimental studies appear further encouraging. It appears that "postconditioning" the heart (i.e. performing brief episodes of ischemia-reperfusion at the time of reperfusion) is as protective as preconditioning. In other words, a therapeutic intervention performed as late as at the time of reflow can still significantly limit infarct size. Further work is needed to determine whether this may be transferred to the clinical practice.     

Nitric oxide and cerebral ischemic preconditioning

Nitric oxide (NO) is an important mediator of cerebral blood flow and metabolism. As a vasodilator, NO regulates cerebral blood flow, and couples regional brain perfusion with metabolic activity. Following cerebral ischemia, NO levels rise significantly due to activation of neuronal nitric oxide synthase by NMDA receptor mediated calcium entry. Depending on its tissue and enzymatic source, NO may be protective or toxic. This article reviews the effects of NO following cerebral ischemia, the signaling pathways through which NO acts, and its potential roles in cerebral ischemic preconditioning.