Bcl-2、Bax蛋白在NRs抗体预处理后缺氧缺糖海马脑片CA_1区的表达变化

运用海马脑片培养技术、海马脑片缺氧缺糖方法、免疫组织化学染色和图像分析处理技术观察用 NMDA受体亚单位抗体预处理后再缺氧缺糖的海马脑片 CA1 区 Bcl-2和 Bax蛋白的表达变化 ,以探究其亚单位与海马脑片缺氧缺糖性损伤的关系。结果显示 ,各实验组海马脑片 CA1 区均有不同程度 Bcl-2、Bax蛋白表达和细胞缺失形成的空洞。 Bcl-2蛋白在 NR1+ OGD组、NR2 A+ OGD组和 NR2 A + NR2 B+ OGD组 CA1 区的表达均明显弱于 OGD组 (3组均 P<0 .0 5 ) ;其在 NR2 B+ OGD组和HOTC组的表达则强于 OGD组 (两者 P<0 .0 5 )。 Bax蛋白在 NR1+ OGD组、NR2 A+ OGD组和 NR2 A+ NR2 B+ OGD组的表达均强于 OGD组 (NR2 A+ OGD组 P<0 .0 5 ) ;在 NR2 B+ OGD组和 HOTC组其表达则明显弱于 OGD组 (后者 P<0 .0 5 )。结论 :单纯缺氧缺糖可引起海马脑片 CA1 区锥体细胞的迟发性损伤 ,同时引起 Bcl-2蛋白和 Bax蛋白的表达变化 ;预加 NMDA受体亚单位 NR1、NR2 A抗体和 NR2 A+ NR2 B抗体可以加重缺氧缺糖性海马脑片 CA1 区细胞损伤程度 ;预加 NR2 B抗体则可减轻其损伤程度。提示 NMDA受体亚单位成分的变化可以调节 Bcl-2和 Bax蛋白在缺氧缺糖性海马脑片 CA1 区的表达 ,从而调节CA1 区神经元的损伤程度     

HDAC9沉默抑制新生大鼠海马神经元氧糖剥夺/再灌注损伤

目的:研究组蛋白去乙酰化酶9(HDAC9)对氧糖剥夺/再灌注(OGD/R)诱导的新生大鼠海马神经元损伤的影响及其机制,为研究新生儿缺氧缺血性脑损伤奠定基础。方法:体外培养新生SD大鼠海马神经元,建立OGD/R损伤模型。用real-time PCR和Western Blot分别检测HDAC9 m RNA和蛋白表达;转染HDAC9 si RNA沉默其表达,并将细胞分为空白对照组、OGD/R组、OGD/R+scramble si RNA组和OGD/R+HDAC9 si RNA组;MTT法测定神经细胞的存活率,乳酸脱氢酶(LDH)活性检测试剂盒检测LDH漏出率,流式细胞术检测细胞凋亡率,Western Blot检测细胞Bax、Bcl-2和p-STAT3的蛋白表达。此外,用JAK2抑制剂AG490预处理细胞,评价JAK2/STAT3通路在HDAC9沉默对海马神经元OGD/R损伤中的作用。结果:HDAC9在OGD/R损伤的在新生大鼠海马神经元细胞中高表达(P0.05);转染HDAC9 si RNA后,细胞HDAC9表达降低(P0.05);在OGD/R诱导的海马神经元细胞中,下调HDAC9的表达能够显著提高细胞活性,降低LDH渗出率,减少神经细胞凋亡,下调Bax表达,上调Bcl-2表达,上调p-STAT3的表达(P0.05),此外,AG490部分逆转HDAC9沉默对新生大鼠海马神经元细胞OGD/R损伤的抑制作用(P0.05)。结论:HDAC9沉默通过JAK2/STAT3通路抑制新生大鼠海马神经元OGD/R损伤。     

吗啡预处理诱导小鼠离体海马脑片氧糖剥夺耐受中PKCδ的作用

 目的 探讨吗啡预处理诱导小鼠离体海马脑片氧糖剥夺耐受形成的机制。 方法 离体小鼠海马脑片氧糖剥夺(OGD)模拟脑缺血再灌注损伤模型,以孵育液乳酸脱氢酶(LDH)漏出率及脑片细胞存活率为指标,探讨吗啡3?mol/L预处理对不同程度OGD损伤小鼠海马脑片神经元的保护作用,用Western blot检测PKCδ表达。结果 吗啡预处理明显提高OGD5,10及20min脑片细胞存活率,使孵育液LDH漏出减少(P<0.05)。OGD后即刻和再灌注2h后,缺糖缺氧组PKC?膜相关成分蛋白表达明显增高,同时胞质部分蛋白表达明显减少(P<0.05),吗啡预处理对PKC?膜转位变化无明显影响。结论 吗啡预处理减轻小鼠离体海马脑片20min以内氧糖剥夺损伤,其机制可能与PKC?的膜转位激活无关。     

姜黄素对TNF-α损伤大鼠海马神经元的功能性保护作用及机制

目的:观察姜黄素对TNF-α损伤大鼠海马神经元的功能性保护作用并探讨其机制。方法:应用离体脑片记录技术,记录大鼠海马CA1区的兴奋性突触后电位(EPSP),给予Schaffer侧支高频刺激(HFS)诱发长时程增强(LTP),观察不同药物处理组EPSP起始斜率的变化情况。结果:与对照组相比,TNF-α和NMDA(N-甲基D-天冬氨酸)对大鼠海马脑片LTP产生明显的抑制作用(P0.05);而姜黄素可以部分拮抗TNF-α和NMDA对海马脑片LTP的抑制作用,与对照组相比无显著差异(P0.05);TNF-α、姜黄素和NMDA对大鼠海马神经元的基础突触传递没有显著影响。结论:姜黄素对TNF-α损伤的大鼠海马神经元有功能性保护作用,其机制可能是姜黄素部分拮抗TNF-α诱导的神经元细胞膜上的NMDA受体过度激活,维持神经元的长时程增强。     

HIV-1包膜糖蛋白gp120对大鼠海马脑片电生理特性的影响

目的探讨人类免疫缺陷病毒I型(HIV-1)的包膜糖蛋白gp120对大鼠海马脑片CA1区神经元电生理特性及突触传递的影响。方法用盲法全细胞记录技术,观察gp120对大鼠海马脑片CA1区神经元电生理特性及对高频电刺激Schaffer侧支引起的鼠海马长时程增强效应(LTP)的影响。结果①在电流钳,gp120可使终末去极化电流激发快速动作电位的数目增加;②在电压钳,gp120对大鼠海马CA1区神经元的全细胞电流无明显作用;③将gp120(100 pmol/L)与海马脑片共孵育1h后,在钳制电压为-60 mV时,发现HFS后海马CA1区的兴奋性突触后电流(EPSC)显著减小,LTP的强度减少到(108.5±8.0)%(n=11,P<0.01)。结论gp120可使海马神经元的兴奋性增加,并可能通过抑制海马CA1区的LTP诱发参与艾滋病痴呆(HIV-1 associated dementia,HAD)的病理生理过程。     

亚低温减轻氧糖剥夺所致的大鼠海马神经元损伤

 目的： 研究亚低温（31～32　℃）对氧糖剥夺（OGD）损伤的大鼠海马神经元的保护作用并探讨其保护机制。方法：本实验通过体外培养大鼠海马神经元并予以OGD处理,建立了模拟大脑缺血、缺氧的神经元OGD模型;将实验细胞随机分为正常对照组、单纯亚低温组、单纯OGD组以及亚低温+OGD组,通过形态学观察、神经元凋亡率检测以及胞浆内caspase-3活性检测,研究亚低温对神经元OGD的保护作用及其机制。结果：神经元OGD后出现明显的细胞损伤,凋亡率明显升高(P＜0.01);与单纯OGD组比较,亚低温+OGD组细胞损伤明显改善,细胞形态学改善,凋亡率下降(P＜0.05),同时caspase-3活性亦下降(P＜0.05);神经元OGD后caspase-3活性升高,与凋亡率呈正相关（r=0.823,P＜0.05）,神经元经过亚低温和OGD后caspase-3活性与凋亡率亦呈正相关（r=0.841,P＜0.05）。结论：OGD可使caspase-3的活性升高及神经元凋亡率增加。亚低温对神经元OGD的保护作用可能与其抑制caspase-3的活性有关。     

白藜芦醇对人脑皮层锥体神经元Na~+电流缺氧性变化的影响

目的:研究人脑皮层锥体神经元Na~+电流的急性缺氧反应特征以及白藜芦醇(resveratrol,RES)对Na~+电流缺氧反应的影响。方法:采用全细胞膜片钳记录法,在人脑皮层脑片上记录锥体神经元对TTX敏感的电压依赖性Na~+电流,观察急性缺氧和白藜芦醇对Na~+电流幅值和激活性质的影响。结果:(1)急性缺氧使人脑皮层脑片上的锥体神经元Na~+电流呈现短暂的小幅增大后,出现长时程抑制(P0.05),并使Na~+电流的I-V曲线左移(向超极化方向漂移)。(2)AMPA受体阻断剂NBQX阻断了缺氧引起的Na~+电流短暂增大(P0.01),并加剧了Na~+电流的缺氧后抑制(P0.01);GABA_A受体阻断剂Bicuculline对Na~+电流的缺氧性增大和缺氧后抑制无显著性影响(P0.05);二者对缺氧引起的Na~+电流I-V曲线左移均无显著影响。(3)50μmol/L白藜芦醇阻断了Na~+电流的缺氧性增大(P0.01),增强了Na~+电流的缺氧后抑制(P0.05);100μmol/L白藜芦醇显著延迟了Na~+电流的缺氧性反应,使Na~+电流的缺氧性增大现象消失,并使Na~+电流的缺氧后抑制现象衰减(P0.05)。50μmol/L和100μmol/L白藜芦醇均使Na~+电流激活曲线右移,接近正常。结论:人脑皮层锥体神经元Na~+电流对急性缺氧的反应主要表现为长时程抑制;AMPA受体活动可影响Na~+通道对急性缺氧的反应。白藜芦醇对人脑皮层锥体神经元Na~+电流缺氧反应的调节作用与剂量有关,小剂量可模拟NBQX的作用,而大剂量可降低Na~+通道对低氧的敏感性。     

布洛芬通过下调环氧化酶2降低癫痫大鼠海马神经元兴奋性

目的:研究布洛芬对慢性癫痫大鼠海马区环氧化酶2(COX-2)和神经元兴奋性的影响。方法:选用雄性健康SD大鼠48只,随机分为3组,分别为对照组(control)、癫痫组(epilepsy)和治疗组(ibuprofen)。运用戊四氮(PTZ)诱导建立慢性癫痫大鼠模型并用布洛芬干预,采用行为学观察检测大鼠癫痫发作水平,运用免疫组织化学染色和Western Blot技术检测大鼠海马区COX-2的表达情况,运用全细胞膜片钳技术收集并分析大鼠海马区动作电位的变化情况。结果:与对照组相比,癫痫组大鼠癫痫发作明显,海马区COX-2表达升高,海马神经元兴奋性升高(P 0.05);治疗组大鼠癫痫发作等级降低,海马区COX-2表达明显降低,海马神经元兴奋性降低(P 0.05)。结论:布洛芬通过下调COX-2降低癫痫大鼠海马神经元的兴奋性,降低癫痫发作强度,具有一定的保护作用。     

ROS介导线粒体ATP敏感性钾通道开放剂对缺氧脑的保护作用

目的：观察线粒体ATP敏感性钾通道(mitoKATP)及活性氧（ROS）在缺氧脑保护中的作用及其相互关系。 方法： 采用脑片灌流及电生理学技术，细胞外记录海马CA1区的群体锋电位(PS)和缺氧去极化电位(HD)。 结果： 用mitoKATP开放剂diazoxide (300 μmol/L) 预处理海马脑片，可延长HD的潜伏期及缺氧后PS消失的时间，提高复氧后PS的恢复率。该作用可被mitoKATP阻断剂5-hydroxydecanoic acid (200 μmol/L) 所阻断。以ROS清除剂N-2-mercaptopropionyl glycine (MPG) (500 μmol/L) 预处理海马脑片，可减弱diazoxide 的作用。单独使用MPG对PS及HD无明显影响。 结论： ROS介导了mitoKATP开放剂对缺氧脑的保护作用。     

在脑片水平上突触可塑性长时程增强的研究进展

长时程增强(LTP)是突触效能的重要表现形式,是研究学习与记忆突触机制的客观指标.近年来随着脑片技术的发展,很多关于LTP的实验研究都在脑片水平上进行.介绍了海马脑片CA1区LTP的调节表达机制的研究,海马脑片上诱导产生的LTP的特征和脑片条件的关系,多巴胺转运蛋白阻断剂通过活化D3多巴胺受体增强海马脑片CA1区LTP,以及激活大鼠海马脑片CA1区突触β-肾上腺素能受体增强联合LTP的研究,综述了在脑片水平上研究LTP的诱导表达维持及调节等方面的研究动态和进展.     

Oxytocin is neuroprotective against oxygen–glucose deprivation and reoxygenation in immature hippocampal cultures

Oxytocin triggers an excitatory-to-inhibitory switch in GABA (γ-aminobutyric acid) actions in immature neurons and this was found to increase their resistance to anoxic episodes. In this study we examined the neuroprotective effect of oxytocin on immature hippocampal cultures subjected to oxygen–glucose deprivation (OGD) both immediately after the insult, as well as after 6 h of reoxygenation. We measured metabolic activity fluorometrically using resazurin and found that cellular viability was increased in the oxytocin treated group both immediately after OGD, as well as after 6 h of reoxygenation. While the oxytocin receptor antagonist atosiban blocked the effect of oxytocin, the Na⁺–K⁺–2Cl⁻ cotransporter (NKCC1) blocker bumetanide protected neurons after reoxygenation. The effects of oxytocin are dose-related. Our results suggest that oxytocin exerts a prolonged neuroprotective action on fetal neurons. Perinatal pharmacologic manipulation of oxytocin receptors may have detrimental effects by increasing susceptibility of the fetal brain to hypoxic-ischemic insults.     

亚低温对缺氧缺血新生大鼠海马星形胶质细胞增殖和凋亡的影响

目的观察亚低温对新生大鼠海马星形胶质细胞增殖和凋亡的影响,以探讨亚低温对缺氧缺血脑损伤保护作用的机制。方法①体外实验：取3日龄大鼠海马脑片,培养至第4天用氧糖剥夺法制备标本,于33℃（亚低温组）和37℃培养48h（常温组）;对照组脑片不进行氧糖剥夺处理,37℃培养7d。采用免疫荧光染色方法观察培养脑片星形胶质细胞的活化和增殖。②体内实验：取7日龄大鼠,分手术组和假手术组。手术组永久性结扎左侧颈总动脉,然后置于含8%O2＋92%N2中缺氧2h,制备缺氧缺血模型,分为手术亚低温亚组和手术常温亚组。假手术组仅分离左侧颈总动脉,不结扎,不予缺氧处理,分为假手术常温亚组和假手术亚低温亚组。各组于术后3和7d处死取材,采用免疫荧光染色方法检测海马星形胶质细胞的活化、增殖和凋亡。结果①体外实验：氧糖剥夺后3d常温组较对照组胶质纤维酸性蛋白（GFAP）阳性细胞数量明显增多;亚低温组与常温组比较,GFAP阳性细胞数量明显减少。②体内实验：术后3和7d亚低温组GFAP阳性细胞数量较常温组显著降低,较常温对照组和亚低温对照组显著增高。GFAP与caspase-3免疫荧光双标记结果显示,术后3d常温组海马区84.5%GFAP阳性细胞表达caspase-3,亚低温组仅32.3%GFAP阳性细胞表达caspase-3,差异有统计学意义。结论亚低温能减轻新生大鼠缺氧缺血后海马星形胶质细胞的活化增殖和凋亡。     

Functional response of hippocampal CA1 pyramidal cells to neonatal hypoxic-ischemic brain damage

Perinatal hypoxic-ischemic (H-I) is a major cause of brain injury in the newborn. The hippocampus is more sensitive to H-I injury than the other brain regions. It is believed that H-I brain damage causes a loss of neurons in the central nervous system. The patterns of neuronal death include apoptosis and necrosis. With regard to the responses of neurons, the neural functional changes should be earlier than the morphologic changes. The aim of the present study is to evaluate the electrophysiological characteristics and the synaptic transmission functions. Seven-day-old Sprague-Dawley rat pups were randomly divided into sham operation and H-I groups. The patch clamp, immunohistochemistry and Western blotting techniques were used to achieve this objective. The results of the study showed a decrease in neuronal excitability and a significant increase in the frequency of spontaneous excitatory postsynaptic currents and the duration of EPSCs in the CA1 pyramidal cells of H-I brain damage rats. The glutamate transporter subtype 1 (GLT-1) expression level of the hippocampal CA1 area in the H-I group was decreased compared with the control. There was no difference in the amplitude of excitatory postsynaptic currents and should be no difference in the expression of alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor (AMPAR), N-methyl-d-aspartate receptor (NMDAR) and synaptophysin between the control and H-I brain injury group. These results revealed that changes of electrophysiological characteristics and synaptic functions occur instantly after H-I brain damage in the hippocampal pyramidal cells of neonatal rats. The failure to eliminate glutamate should be one of the important factors of excitotoxicity injury on hippocampal CA1 pyramidal cells, while neuronal excitation was not increased in the H-I brain injury model.     

Enhanced neuronal damage after ischemic insults in mice lacking Kir6.2-containing ATP-sensitive K+ channels

Adenosine triphosphate (ATP)-sensitive potassium (KATP) channels, incorporating Kir6.x and sulfonylurea receptor subunits, are weak inward rectifiers that are thought to play a role in neuronal protection from ischemic insults. However, the involvement of Kir6.2-containing KATP channel in hippocampus and neocortex has not been tested directly. To delineate the physiological roles of Kir6.2 channels in the CNS, we used knockout (KO) mice that do not express Kir6.2. Immunocytochemical staining demonstrated that Kir6.2 protein was expressed robustly in hippocampal neurons of the wild-type (WT) mice and absent in the KO. To examine neuronal sensitivity to metabolic stress in vitro, and to ischemia in vivo, we 1) exposed hippocampal slices to transient oxygen and glucose deprivation (OGD) and 2) produced focal cerebral ischemia by middle cerebral artery occlusion (MCAO). Both slice and whole animal studies showed that neurons from the KO mice were severely damaged after anoxia or ischemia, whereas few injured neurons were observed in the WT, suggesting that Kir6.2 channels are necessary to protect neurons from ischemic insults. Membrane potential recordings from the WT CA1 pyramidal neurons showed a biphasic response to OGD; a brief hyperpolarization was followed by a small depolarization during OGD, with complete recovery within 30 min after returning to normoxic conditions. By contrast, CA1 pyramidal neurons from the KO mice were irreversibly depolarized by OGD exposure, without any preceding hyperpolarization. These data suggest that expression of Kir6.2 channels prevents prolonged depolarization of neurons resulting from acute hypoxic or ischemic insults, and thus protects these central neurons from the injury.     

Neuroprotective potential of ceftriaxone in in vitro models of stroke

Astrocytic glutamate transporters are considered an important target for neuroprotective therapies as the function of these transporters is abnormal in stroke and other neurological disorders associated with excitotoxicity. Recently, Rothstein et al., [Rothstein JD, Patel S, Regan MR, Haenggeli C, Huang YH, Bergles DE, Jin L, Dykes Hoberg M, Vidensky S, Chung DS, Toan SV, Bruijn LI, Su ZZ, Gupta P, Fisher PB (2005) Beta-lactam antibiotics offer neuroprotection by increasing glutamate transporter expression. Nature 433:73-77] reported that beta-lactam antibiotics (including ceftriaxone, which easily crosses the blood-brain barrier) increase glutamate transporter 1 (GLT-1) expression and reduce cell death resulting from oxygen-glucose deprivation (OGD) in dissociated embryonic cortical cultures. To determine whether a similar neuroprotective mechanism operates in more mature neurons, which show a different pattern of response to ischemia than primary cultures, we exposed acute hippocampal slices obtained from rats treated with ceftriaxone for 5 days (200 mg/kg; i.p.) to OGD. Whole-cell patch clamp recording of glutamate-induced N-methyl-d-aspartate (NMDA) currents from CA1 pyramidal neurons showed a larger potentiation of these currents after application of 15 microM dl-threo-beta-benzyloxyaspartic acid (TBOA; a potent blocker of glutamate transporters) in ceftriaxone-injected animals than in untreated animals, indicating increased glutamate transporter activity. Western blot analysis did not reveal GLT-1 upregulation in the hippocampus. Delay to OGD-induced hypoxic spreading depression (HSD) recorded in slices obtained from ceftriaxone-treated rats was longer (6.3+/-0.2 vs. 5.2+/-0.2 min; P<0.001) than that in the control group, demonstrating a neuroprotective action of the antibiotic in this model. The effect of ceftriaxone was also tested in organotypic hippocampal slices obtained from P7-9 rats (>14 days in vitro). OGD or glutamate (3.5-5.0 mM) damaged CA1 pyramidal neurons as assessed by propidium iodide (PI) fluorescence. Similar damage was observed after pre-treatment with ceftriaxone (10-200 microM; 5 days) and ceftriaxone exposure did not result in GLT-1 upregulation as assayed by Western blot. Treatment of slice cultures with dibutyryl cAMP (100-250 microM; 5 days) increased GLT-1 expression but did not reduce cell damage induced by OGD or glutamate. Thus we confirm the neuroprotective effect of antibiotic exposure on OGD-induced injury, but suggest that this action is related to independent modulation of transporter activity rather than to the level of GLT-1 protein expression. In addition, our results indicate that the protective effects of beta-lactam antibiotics are highly dependent on the experimental model.     

构建全脑缺血与鞘内置管结合的SD大鼠模型

背景：脑缺血性损伤可导致神经元不可逆性功能丧失,而鞘内用药是目前临床镇痛及神经保护类药物的常用施药途径。大脑损伤后可于鞘内注入神经保护类物质进行干预的实验动物模型是相关神经保护类物质研究的基础。 目的：构建全脑缺血与鞘内置管相结合的动物模型。 方法：采用Pulsinelli四血管阻断全脑缺血模型结合鞘内置管术,将实验大鼠进行四血管阻断与鞘内置管,另设置假手术组不进行血管阻断。术后除假手术组外,一部分大鼠注射虎纹蜘蛛毒素Ⅰ (1.0 µL/kg),设为虎纹蜘蛛毒素Ⅰ组;另一部分大鼠注射等量生理盐水,设为模型组。缺血再灌注4 d后用尼氏染色观察脑组织海马CA1区锥体神经元结构的变化。 结果与结论：假手术组可见大量锥体神经元,排列整齐紧密,胞浆染色清晰,呈蓝色,胞浆内尼氏体均匀丰富。虎纹蜘蛛毒素Ⅰ组锥体神经元排列较整齐,稀疏分布,出现少量胞体浓缩、深染,细胞体积缩小等特征。模型组可见锥体神经元排列散乱,层次不完整,稀疏分布,出现大量胞体浓缩、深染,细胞体积缩小等特征。虎纹蜘蛛毒素Ⅰ组相比模型组大鼠海马CA1区锥体神经元受损程度变小。结果提示,实验成功构建了全脑缺血与鞘内置管相结合的大鼠模型。     

Neuroprotective effects of bone marrow stromal cells on rat organotypic hippocampal slice culture model of cerebral ischemia

Organotypic hippocampal slice cultures prepared from newborn rats were maintained in vitro for 9 days. Cultures were then exposed to 30 min of combined oxygen-glucose deprivation (OGD). After OGD, the area covered by neurites was decreased. The dead cells of hippocampal slices in the ischemia group were 40.4% at day 3 and 41.6% at day 7 after OGD. The ultrastructure of the CA1 region of the slices was seriously damaged. While hippocampal slices were cultured in combination with bone marrow stromal cells (MSCs), the average area covered by neurites was comparatively increased. The dead cells were only 25.2% at day 3 and 27.1% at day 7 after coculture. The damage of the ultrastructure of the CA1 region in the coculture group was reduced significantly. Thus, in an in vitro model of simulated ischemia, MSCs can promote the outgrowth of neurites from hippocampal slices and alleviate cell damage. The neuroprotective effect might be mediated through diffusible neurotrophic factors secreted from MSCs.     

Neuroprotective effects of interleukin-10 and tumor necrosis factor-alpha against hypoxia-induced hyperexcitability in hippocampal slice neurons

In our previous experiments we have demonstrated that repeated exposures of rat hippocampal slices to brief episodes of hypoxia induce a sustained decrease in the threshold of stimulus-evoked epileptiform discharges in CA1 pyramidal neurons. The aim of this study was to investigate the comparative effects of interleukin-10 (IL-10) and tumor necrosis factor-alpha (TNF-alpha) on the hyperexcitability of CA1 pyramidal neurons induced by brief episodes of hypoxia in the rat hippocampal slices. The method of field potentials measurement in CA1 region of hippocampal slices have been described in our previous work [O. Godukhin, A. Savin, S. Kalemenev, S. Levin, Neuronal hyperexcitability induced by repeated brief episodes of hypoxia in rat hippocampal slices: involvement of ionotropic glutamate receptors and L-type Ca2+ channels, Neuropharmacology 42 (2002) 459-466]. The principal results of our work are summarized as follow. Pro-inflammatory cytokine TNF-alpha (0.8, 4 and 20 ng/ml) and anti-inflammatory cytokine IL-10 (1 and 10 ng/ml) significantly reduced the hyperexcitability in CA1 pyramidal neurons induced by brief episodes of hypoxia in the rat hippocampal slices. The neuroprotective effects of IL-10 and TNF-alpha against the hypoxia-induced hyperexcitability were mediated by anti-hypoxic actions of these cytokines through, possibly, mechanism of preconditioning.     

脐血间充质干细胞移植修复缺氧缺血损伤新生大鼠的脑功能

背景：课题计划从神经细胞替代、促进内源性神经干细胞增殖和分化、保护神经元、促进突触重建以及减轻脑白质损伤等方面来探讨脐血间充质干细胞系统移植对新生大鼠缺氧缺血脑损伤后神经功能的修复作用及其机制。 目的：观察脐血间充质干细胞由静脉途径移植透过血脑屏障进入脑组织内,对新生大鼠缺氧缺血性脑损伤后脑功能修复的影响。 方法：7 d龄SD新生鼠分为3组：假手术组仅分离出左侧颈总动脉而不结扎;缺氧缺血脑损伤组制备缺氧缺血脑损伤模型;细胞移植组在缺氧缺血性脑损伤后第8天尾静脉移植人脐血间充质干细胞,前两组尾静脉注射等量的生理盐水。 结果与结论：免疫荧光观察显示移植后5周脐血间充质干细胞迁移到海马,Nissl染色结果显示脐血间充质干细胞移植后,左侧海马DG区锥体细胞尼氏小体明显增加,提示间充质干细胞移植后可分化为神经元。行为学测试结果显示：与假手术组相比,缺氧缺血脑损伤组在T迷宫实验中,自发改变率下降,在放射形迷宫中觅水时间延长,错误次数及重复次数明显增加(P < 0.05);脐血间充质干细胞静脉移植5周后,上述行为学指标均显著改善(P < 0.05)。提示脐血间充质干细胞静脉移植治疗明显改善和提高了缺氧缺血脑损伤大鼠远期的学习记忆和空间辨别能力。     

白藜芦醇对新生大鼠神经元缺血缺氧时SDF-1/CXCR4通路抗凋亡作用的调控机制

目的:探究白藜芦醇(RSV)对缺血缺氧诱导的新生大鼠脑神经元凋亡及基质细胞衍生因子1(SDF-1)/CXC趋化因子受体4(CXCR4)通路的作用和机制。方法:体外培养新生大鼠皮质神经元,给予氧糖剥夺(OGD)模拟新生儿缺血缺氧性脑病(HIE)模型。首先将细胞随机分成4组:对照(control)组、HIE组、HIE+RSV低剂量(10μmol/L)组和HIE+RSV高剂量(50μmol/L)组。OGD处理2 h后加入相应剂量的RSV继续培养24 h,通过流式细胞术检测细胞凋亡,Western blot检测凋亡相关蛋白及SDF-1和CXCR4的蛋白表达水平,real-time PCR检测SDF-1和CXCR4的mRNA表达水平。然后使用CXCR4抑制剂AMD3100与RSV共同处理OGO损伤的细胞24h,检测SDF-1/CXCR4通路阻断后RSV对细胞凋亡和凋亡相关蛋白表达水平的影响。结果:RSV能够抑制OGD诱导的神经元凋亡,下调活化的caspase-3和细胞色素C的水平,上调Bcl-2/Bax比值(P0.05)。与对照组相比,OGD导致SDF-1和CXCR4表达增加;与模型组相比,RSV能够上调SDF-1和CXCR4的表达(P0.05);使用AMD3100阻断SDF-1/CXCR4通路减弱了RSV抑制OGD诱导的细胞凋亡的作用。结论:RSV可抑制缺血缺氧诱导的新生大鼠神经元凋亡,其机制可能是通过上调SDF-1/CXCR4通路发挥作用的。