银杏内酯通过激活Nrf2和CREB核转位促进抗氧化和抗凋亡基因表达发挥抗脑缺血再灌注损伤作用

目的研究银杏二萜内酯葡胺注射液(DGMI)抗大鼠脑缺血再灌注损伤的作用及机制。方法建立大鼠脑缺血再灌注损伤模型,缺血1.5 h,再灌注24 h后对神经行为学缺损程度评分,TTC测定大鼠脑梗死体积,Western印迹和免疫荧光测定大鼠脑组织中蛋白表达。结果 DGMI能够显著改善脑缺血再灌注损伤导致的大鼠神经行为学缺损症状,提高运动神经功能,减小脑梗死体积及水肿程度,抑制受损脑区的神经元凋亡。一方面,DGMI能够激活PI3K/Akt/Nrf2通路,促进Nrf2的核转位,增加HO-1蛋白的表达,提高受损脑区中Neu N与Nrf2双阳性细胞的百分比。另一方面,DGMI也能够激活PI3K/Akt/CREB通路,提高CREB磷酸化水平和受损脑区中Neu N与p-CREB双阳性细胞的百分比。结论 DGMI通过激活PI3K/Akt/Nrf2和PI3K/Akt/CREB通路共同发挥抗脑缺血再灌注损伤作用。     

PI3K/Akt信号通路与肝纤维化

PI3K/Akt信号通路为细胞内重要信号传导通路之一,在促进细胞增殖、抑制凋亡的过程中发挥重要作用。PI3K/Akt信号通路与肝纤维化的发生、发展密切相关。通过干预PI3K/Akt信号通路,研究肝纤维化的发病机制和药物治疗是有意义的途径。该文就PI3K/Akt信号通路的构成、转导途径及其在肝纤维化中的作用作一综述。     

异鼠李素激活PI3K/Akt/GSK-3β/CREB信号通路减轻鱼藤酮诱导的PC12细胞损伤

目的探讨异鼠李素(isorhamnetin,ISO)是否能够通过激活PI3K/Akt/GSK-3β/CREB通路减轻鱼藤酮对PC12细胞的损伤作用。方法采用MTT法检测细胞活力,LDH检测乳酸脱氢酶释放,Western blot法测定p-Akt、Akt、p-GSK-3β、GSK-3β、p-CREB和CREB蛋白表达。结果与对照组相比,鱼藤酮损伤后PC12细胞活力明显降低,CREB的磷酸化程度显著降低。异鼠李素预处理组细胞存活率和磷酸化CREB的表达均高于鱼藤酮损伤模型组。此外,异鼠李素预处理增强了鱼藤酮损伤后PC12细胞中Akt和GSK-3β的磷酸化程度。加入PI3K抑制剂LY294002可以抑制Akt、GSK-3β和CREB的磷酸化水平,从而部分消除异鼠李素对鱼藤酮损伤PC12细胞的神经保护作用。结论异鼠李素可能通过PI3K/Akt/GSK-3β/CREB信号通路发挥PC12细胞保护作用。     

网膜素-1基于动脉粥样硬化调节作用的脑保护研究进展

目的对网膜素-1在动脉粥样硬化中的血管保护作用及对缺血性脑卒中潜在保护作用和预测作用进行综述。方法根据近十年发表的英文文献,归纳并论述网膜素-1在动脉粥样硬化中涉及的分子机制,进而推测其在缺血性脑卒中方面发挥的预测及保护作用。结果网膜素-1在动脉粥样硬化病理过程中涉及多种不同的信号通路,主要从ERK/NF-κB、Akt/eNOS、AMPK、eNOS信号通路、PPAR-γ、NO、炎症因子等方面进行论述。在动脉粥样硬化模型中,网膜素-1能抑制ERK/NF-κB信号通路、上调PPAR-γ、促进Akt及eNOS磷酸化,抑制相关炎症因子,减轻动脉粥样硬化的症状,发挥保护缺血性脑组织的作用。结论对网膜素-1在动脉粥样硬化中的相关作用机制及其在缺血性脑卒中方面发挥预测和保护作用的研究,为抗缺血性脑卒中药物的研发提供新的途径和理论依据。     

磷脂酸肌醇-3-激酶/蛋白激酶B信号通路在肺部疾病中的作用研究进展

磷脂酸肌醇-3-激酶(PI3K)/蛋白激酶B(Akt)信号通路是细胞内与增殖、分化和凋亡相关的信号通路，是机体自我保护的重要通路。PI3K被激活后会使其下游分子Akt磷酸化，进而抑制细胞凋亡、调控细胞生存及增殖。PI3K/Akt信号通路在众多肺系疾病，如急性肺损伤、肺炎、哮喘、肺纤维化、肺癌等的发展进程中起着重要作用。该文对PI3K/Akt信号通路在肺系疾病进展中的作用机制进行了综述。     

红景天苷的神经保护作用及作用机制研究进展

动物实验结果显示红景天苷对多种原因引起的神经细胞和脑组织损伤均有保护作用,有望用于周围神经损伤以及脑缺血性和神经变性疾病（如脑梗死、老年痴呆、帕金森病、癫痫、抑郁、抽动秽语综合征、肌萎缩性侧索硬化症和糖尿病脑病等）的防治。其神经保护作用机制主要包括3个方面：（1）通过抗氧化作用,抑制NOX2/ROS/MAPKs和REDD1/mTOR/p70S6K信号通路,激活AMPK/SIRT1、RhoA-MAPK和PI3K/Akt信号通路,对抗各种损伤因子引起的氧化应激,抑制炎性细胞因子表达,防止细胞内Ca²⁺超载和半胱天冬酶-3活化,保护神经细胞和干细胞免遭凋亡性损伤;（2）抑制淀粉样前体蛋白β位裂解酶-1的表达和β-分泌酶活性,阻滞内源性伤害因子β-淀粉样肽生成;（3）通过阻滞Notch信号通路,促进BMP信号通路,上调多种神经营养因子表达,诱导间充质干细胞和神经干细胞定向分化成神经元,提高许旺细胞增殖和功能,从而加速神经修复、再生和功能恢复。     

P13K/Akt信号转导通路的研究进展

PI3K/Akt信号传导通路在恶性肿瘤的发生、发展、治疗及转归中发挥着重要作用,PI3K作为联系胞外信号与细胞应答效应的桥梁分子,在一系列上游或旁路信号分子的影响下,作用于下游的信号分子对细胞的凋亡起非常重要的调节作用.在许多研究中已经证实PI3K和Akt的抗凋亡时,Akt的表达水平增高并通过保护细胞免受凋亡而促进癌细胞的生长.现就PI3K/Akt信号通路的组成与功能、调节以及其抗恶性肿瘤细胞凋亡作用机理等方面的研究进展作一综述.     

孕酮和PI3K/Akt信号通路在缺氧缺血性脑损伤中的研究现状

磷酸肌醇-3羟激酶/蛋白激酶B(PI3K/Akt)是一种经典的抗凋亡、促存活信号传导通路,在脑梗死、帕金森病、癫痫等神经系统疾病中发挥调节作用。孕酮是一种脂溶性甾体激素,对创伤性脑损伤、卒中、阿尔茨海默病等患者的神经保护有重要作用,其与p-Akt上调有关。本文通过收集讨论新生儿缺氧缺血性脑病(HIE)、孕酮和PI3K/Akt的研究报道,以期为进一步探讨孕酮在HIE中的神经保护作用与PI3K/Akt信号通路的关系提供一定的理论依据。     

PI3K/Akt通路在糖尿病心肌病中的研究进展

糖尿病心肌病(diabetic cardiomyopathy,DCM)是由糖尿病引发心肌结构和功能的改变一类原发性心肌病变,区别于冠状动脉粥样硬化、高血压以及病毒等因素引起的继发性心肌病。磷酯酰肌醇3激酶(phosphatidylinositol-3 kinase,PI3K)/Akt作为人体重要的信号传导通路,参与机体正常生长繁殖、调节新陈代谢等功能。PI3K/Akt信号通路的调控因子包括沉默信息调节因子1、同源性磷酸酶-张力蛋白、糖原合成酶激酶3β、雷帕霉素靶蛋白等。DCM发病过程中,PI3K/Akt信号通路的作用包括调节血糖水平、调节脂质代谢、保护内皮细胞、减轻炎症反应、改善心功能并抵抗纤维化、调节心肌细胞凋亡等。PI3K-Akt信号通路抑制剂的研发为PI3K-Akt通路靶向治疗提供了可能性。该文综述了PI3K/Akt通路在DCM中的研究进展。     

磷脂酰肌醇-3磷酸激酶/AKT/雷帕霉素靶蛋白信号通路参与中枢神经损伤保护与修复的研究进展

中枢神经细胞对各种损伤刺激耐受差,损伤后神经修复困难.因此促进神经保护增强神经再生能力已成为神经治疗关键.磷脂酰肌醇-3磷酸激酶/AKT/雷帕霉素靶蛋白(PI3K/AKT/mTOR)信号通路是调节细胞周期的重要通路,在细胞增殖、生长、分化过程中起中心调控作用,在神经损伤过程中通过激活PI3K/AKT/mTOR信号通路可减少神经细胞死亡,促进神经修复.该文对PI3K/AKT/mTOR信号通路在中枢神经损伤保护作用、修复机制及可能风险作一综述,探讨将PI3K/AKT/mTOR信号通路作为靶点治疗中枢神经疾病.     

Major role of the PI3K/Akt pathway in ischemic tolerance induced by sublethal oxygen-glucose deprivation in cortical neurons in vitro

Ischemic preconditioning can provide protection to neurons from subsequent lethal ischemia. The molecular mechanisms of neuronal ischemic tolerance, however, are still not well-known. The present study, therefore, examined the role of MAPK and PI3K/Akt pathways in ischemic tolerance induced by preconditioning with sublethal oxygen-glucose deprivation (OGD) in cultured rat cortical neurons. Ischemic tolerance was simulated by preconditioning of the neurons with sublethal 1-h OGD imposed 12 h before lethal 3-h OGD. The time-course studies of relative phosphorylation and expression levels of ERK1/2, JNK and p38 MAPK showed lack of their involvement in ischemic tolerance. However, there were significant increases in Akt phosphorylation levels during the reperfusion period following preconditioned lethal OGD. In addition, Bcl-2 associated death promoter (Bad) and GSK-3β were also found to be inactivated during that reperfusion period. Finally, treatment with an inhibitor of PI3K, wortmannin, applied from 15 min before and during lethal OGD abolished not only the preconditioning-induced neuroprotection but also the Akt activation. Concomitant with blockade of the Akt activation, PI3K inhibition also resulted in activation of Bad and GSK-3β. The results suggest that ischemic tolerance induced by sublethal OGD preconditioning is primarily mediated through activation of the PI3K/Akt pathway, but not the MAPK pathway, in rat cortical neurons.     

Activation of PI3-K/Akt pathway for thermal preconditioning to protect cultured cerebellar granule neurons against low potassium-induced apoptosis

AIM: This study was designed to investigate whether the activation of the phosphatidylinositol 3-kinase (PI3-K)/Akt pathway is required for thermal preconditioning to protect rat cerebellar granule neurons (CGN) against apoptosis induced by low potassium, and to explore the possibility of a link between the upregulated heat shock protein (HSP)70 expression and Akt activation in the acquisition of neuroprotection induced by thermal preconditioning. METHODS: CGN cultured for 8 d in vitro were switched to 5K medium for 24 h after thermal preconditioning (TP; 43.5 degree for 90 min, then 37 degree for 1 h). To study the role of the PI3-K/Akt pathway, a PI3-K inhibitor, LY294002 (20 micromol/L) was added into the cultures 1 h before TP. 3-(4,5-dimethylthiazol-2-yl)2,5-diphenyltetrazolium bromide (MTT) assay and fluorescein diacetate staining were used to determine cell viability. Hoechst 33258 staining and agar gel electrophoresis were used to test the morphological and biological characters of CGN. Western blot analysis was employed to detect the levels of phospho-Akt, phospho-glycogen synthase kinase 3beta (GSK3beta) Akt, GSK3beta, and HSP70. RESULTS: TP protected CGN against apoptosis induced by low potassium. LY294002 inhibited the neuroprotective effect on CGN induced by TP. TP induced a robust activation of Akt and the inactivation of GSK3beta via PI3-K. Furthermore, the activation of the PI3-K/Akt pathway by TP persisted for 24 h in the 5K cultures. LY294002 (20 micromol/L) failed to inhibit the upregulated HSP70 expression induced by TP. CONCLUSION: The activation of the PI3-K/Akt pathway is required for TP to protect CGN against apoptosis induced by low potassium, but the neuroprotective effect by Akt activation is not mediated through the downstream induction of HSP70 expression.     

Inhibition of Autophagy Contributes to Melatonin-Mediated Neuroprotection Against Transient Focal Cerebral Ischemia in Rats

Melatonin, a natural product of the pineal gland, has been shown to protect against ischemic stroke, but the molecular mechanisms underlying its protective function are not fully understood. In the present study, we tested whether melatonin could protect against ischemia– reperfusion (I/R) injury to rat brain by targeting the autophagy pathway. The I/R brain injury was induced by the established rat transient middle cerebral artery occlusion model. We found intraperitoneal injection of melatonin can ameliorate rat brain injury as evidenced by multiple morphological and behavioral criteria, such as infarct size, neurological score, serum creatine kinase, and lactate dehydrogenase content, as well as pyknotic-positive cells. Further studies revealed that the beneficial effects of melatonin is through targeting the autophagy pathway by inhibiting expression of beclin-1 and conversion of LC3, as well as activating the PI3K/Akt pro-survival pathway. To further confirm this finding, the autophagy pathway was activated by lentiviral mediated beclin-1 delivery and the PI3K/Akt pathway was inhibited by a pharmacological inhibitor, LY294002. In both manipulations, the beneficial effects of melatonin were greatly abolished. Taken together, our study suggested melatonin plays a protective role against I/R brain injury by inhibiting autophagy and activating the PI3K/Akt pro-survival pathway.     

Preventive neuroprotection： from experimental data to therapeutic

The concept of preventive neuroprotection is based on experimental concept of brain ischemic tolerance in which a cerebral resistance against ischemia consequences is induced prior to its occurrence. Pharmacological agents mimicking the biological mechanisms observed in brain ischemic tolerance might increase the resistance of patients with high stroke risk to the deleterious effects of brain ischemia. Activation of cytoprotective proteins     

异氟醚预处理对大鼠脑缺血/再灌注损伤细胞内游离钙的影响

目的:观察异氟醚对缺血再灌注大鼠活体脑片细胞内游离钙的影响,探讨异氟醚脑保护作用的机制。方法:采用线栓法阻闭大鼠大脑中动脉造成局灶性脑缺血,并于缺血2h后拔出栓线给予再灌注。利用细胞内钙离子荧光探针Fluo-3/AM在激光共聚焦显微镜下观察再灌注2h后大鼠脑片细胞内荧光强度。比较异氟醚预处理1h对缺血再灌注大鼠活体脑片额顶叶皮质及纹状体区域Ca2 浓度的影响。结果:缺血再灌注损伤大鼠缺血侧脑片皮层及纹状体Ca2 荧光强度明显升高。脑缺血前给予异氟醚预处理1h可抑制缺血侧大脑皮层细胞内Ca2 含量的增加,对纹状体细胞内Ca2 含量的影响无统计学差异。结论:缺血前给予异氟醚预处理可有效减轻额顶叶皮层细胞内的钙超载,对纹状体区域脑细胞内游离钙水平影响较小,提示异氟醚的脑保护作用在不同脑区存在差异。     

Intranasal Delivery of Exendin-4 Confers Neuroprotective Effect Against Cerebral Ischemia in Mice

Exendin-4 is now considered as a promising drug for the treatment of cerebral ischemia. To determine the neuroprotective effects of intranasal exendin-4, C57BL/6J mice were intranasally administered with exendin-4 daily for 7 days before middle cerebral artery occlusion (MCAO) surgery. Intranasally administered exendin-4 produced higher brain concentrations and lower plasma concentrations when compared to identical doses administered interperitoneally. Neurological deficits and volume of infarcted lesions were analyzed 24 h after ischemia. Intranasal administration of exendin-4 exhibited significant neuroprotection in C57BL/6 mice subjected to MCAO by reducing neurological deficit scores and infarct volume. The neuroprotective effects of exendin-4 were blocked by the knockdown of GLP-1R with shRNA. However, exendin-4 has no impact on glucose and insulin levels which indicated that the neuroprotective effect was mediated by the activation of GLP-1R in the brain. Exendin-4 intranasal administration restored the balance between pro- and anti-apoptotic proteins and decreased the expression of Caspase-3. The anti-apoptotic effect was mediated by the cAMP/PKA and PI3K/Akt pathway. These findings provided evidence that exendin-4 intranasal administration exerted a neuroprotective effect mediated by an anti-apoptotic mechanism in MCAO mice and protected neurons against ischemic injury through the GLP-1R pathway in the brain. Intranasal delivery of exendin-4 might be a promising strategy for the treatment of ischemic stroke.     

ZW1-2对局灶脑缺血小鼠纹状体、皮质及海马脑区BDNF和VEGF蛋白表达的影响

目的观察化合物zome wermel 1-2(ZW1-2)对小鼠永久性局灶脑缺血后的神经功能,以及对脑源性营养因子和血管内皮生长因子的影响。方法制备小鼠永久性局灶脑缺血模型,并分别于脑缺血后2.5 h和7.5 h,灌胃给予不同剂量的化合物ZW1-2,脑缺血后24 h采用免疫组化法测定小鼠各个脑缺血易损区的脑源性神经营养因子和血管内皮生长因子表达情况。结果 ZW1-2能够显著降低小鼠局灶性脑缺血导致的行为功能评分,可以显著提高皮质、纹状体和海马脑区的脑源性神经营养因子表达,显著降低这些脑区中的血管内皮生长因子蛋白表达。结论 ZW1-2具有抗实验性脑缺血作用,其作用机制可能通过调控脑源性神经营养因子以及血管内皮生长因子而起到对脑缺血损伤的治疗作用。     

苦参碱的心脏保护作用及其机制的研究进展

苦参碱对心脏具有正性肌力、负性频率和负性自律性的作用,因此具有广谱的抗心律失常作用。苦参碱对冠脉结扎缺血、缺血再灌注、异丙肾上腺素、高血脂、糖尿病和阿霉素引起的心肌损伤都有保护作用。苦参碱还能阻滞心肌肥大和纤维化的发生、发展。苦参碱保护心脏作用的基本机制是抗氧化、抗炎、降血糖、调血脂作用,由此抑制ROS/TLR4信号通路、PI3K/Akt信号通路和TGF-β诱导的PERK信号通路,激活Akt和STAT3信号通路和AMPKα/UCP2信号通路,上调JAK2/STAT3通路上的HSP70以及JNK、ASK1、e NOS和一氧化氮的表达,提高线粒体ATP酶活性,保护线粒体而减少心肌细胞凋亡、减轻心肌损伤和抑制胶原合成,从而抑制心肌肥大和纤维化。从抗各种心肌缺血性损伤、抗阿霉素诱导的心肌损伤、抗高糖性心肌损伤、抗心肌肥大和纤维化4个方面综述苦参碱的心脏保护作用及其机制。     

PI3K p55γ promoter activity enhancement is involved in the anti-apoptotic effect of berberine against cerebral ischemia-reperfusion

Berberine is a candidate clinical neuroprotective agent against ischemic stroke. In the present study, we examined the influence of the PI3K/Akt pathway in mediating the anti-apoptotic effects of berberine. Oxygen-glucose deprivation and reoxygenation of nerve growth factor-differentiated PC12 cells and primary neurons, and bilateral common carotid artery occlusion in mice were used as in vitro and in vivo ischemia models. We found that the anti-apoptotic effects of berberine against ischemia were indeed mediated by the increased phosphor-activation of Akt (higher p-Akt to total Akt), leading to the intensified phosphorylation of Bad and the decreased cleavage of the pro-apoptotic protease caspase-3. Berberine action is specific for PI3K, rather than the upstream receptor tyrosine kinase. The anti-apoptotic effect is maintained in the presence of tyrosine kinase inhibitor genistein and the epidermal growth factor receptor inhibitor PD153035, but is suppressed by the PI3K inhibitor Ly294002 and the Akt inhibitor Akti-1/2.The unique PI3K regulatory subunit p55γ was upregulated by berberine during ischemia-reperfusion and was not blocked by these inhibitors. We constructed a reporter plasmid to detect PI3K p55γ promoter activity and found that berberine enhanced PI3K p55γ promoter activity during cerebral ischemia-reperfusion.     

Luteolin inhibits apoptosis and improves cardiomyocyte contractile function through the PI3K/Akt pathway in simulated ischemia/reperfusion

Luteolin, a naturally occurring polyphenol flavonoid, has demonstrated to exert myocardial protection effects. However, the mechanisms have not been fully elucidated. In the present study, we investigated whether luteolin pretreatment was associated with cardioprotection in a rat ischemia/reperfusion (I/R) model. Luteolin significantly not only restored contractility of the left ventricle, but also reduced the infarct size and lactate dehydrogenase leakage during I/R. In addition, luteolin pretreatment significantly improved cardiomyocyte shortening amplitude, decreased the apoptotic rate, upregulated Bcl-2 expression, downregulated Bax expression and raised the Bcl-2/Bax ratio under a simulated ischemia/reperfusion (SI/R) condition. Moreover, luteolin pretreatment increased protein kinase B (Akt) phosphorylation, phospholamban phosphorylation and the expression of sarcoplasmic reticulum calcium ATPase following SI/R. The phosphoinositide 3-kinase (PI3K)/Akt pathway is one of the most important intracellular survival signal pathways. To determine whether luteolin-induced cardioprotection was mediated by the PI3K/Akt pathway, we utilized the PI3K inhibitor LY294002. Inhibition of Akt activity markedly abolished luteolin-induced positive contraction and inhibition of apoptosis in SI/R cardiomyocytes. These results showed that luteolin inhibits apoptosis and improves cardiomyocyte contractile function at least partly through the PI3K/Akt pathway in SI/R.