The Effect of Coriaria Lactone on NMDA Receptor Mediated Currents in Rat Hippocampal CA1 Neurons

Summary: To investigate the exact mechanism of epileptogenesis induced by coriaria lactone (CL), the effect of CL on NMDA receptor mediated current (IAsp) in rat hippocampal CA1 neu- rons was investigated by using nystatin perforated whole-cell patch clamp. 10-6-10-4 mol/L Asp acted on NMDA receptors and elicited an inward current (IAsp) at a holding potential (VH) of -40 mV in presence of 10-6 mol/L glycine and absence of Mg2+ extracellularly. CL enhanced NMDA receptor mediated current induced by Asp, but had no effect on threshold concentration, EC50, Hill coefficient as well as maximal-effect concentration and reversal potential of IAsp. The effect had no relationship with holding potential. These results showed that CL could enhance NMDA receptor mediated current to increase [Ca2+]i of neurons by acting on Gly site, thereby inducing epilepsy.

2-aminoethoxydiphenyl borate or lanthanum potentiates transient receptor potential-like channels in rat CA1 hippocampal neurons

Expression of transient receptor potential （TRP） channels is widespread with transcripts distributed throughout the brain. All TRP channel subunits are activated following phospholipase C activation and form cation-selective ion channels. Previous studies examining the existence of TRP channels in hippocampal CA1 pyramidal neurons were based on cultured neurons. Therefore, their relevance for living tissue remains unclear. In the present study, patch-clamp recordings were conducted from CA1 pyramidal neurons in hippocampal slices from 7-day-old rats. Whole-cell currents were obtained from CA1 hippocampal neurons with potentiation effects of 2-aminoethoxydiphenyl borate and lanthanum, revealing that recorded experimental currents were characteristic TRP-like channel currents. Identification of rat hippocampal mRNA transcripts of TRPC4, TRPC5, TRPV1, TRPV2, and TRPV3 channels further verified the expression of characteristic TRP-like channels on rat CA1 hippocampal neurons.

硫酸镁对大鼠海马CA_1区神经元钠电流的抑制作用

利用全细胞膜片钳技术研究了硫酸镁 (MgSO4 )对大鼠海马CA1区神经元钠电流的影响。结果表明 ,MgSO4 可浓度依赖和电压依赖地抑制钠电流 ,半数抑制浓度为 4 0 5mmol/L。这一抑制作用与刺激频率无关。结果还表明 ,4mmol/LMgSO4 不影响钠电流的失活过程 ,却使半数激活电压由 - 5 5 8± 6 8mV变为 - 3 4 2± 6 2mV (n =8,P <0 0 1) ,而激活曲线的斜率因子不变。结果提示 ,MgSO4

SO_2代谢衍生物对大鼠海马CA_1区神经元瞬间外向钾电流和延迟整流钾电流的影响

本文利用全细胞膜片钳技术研究了SO2 代谢衍生物———NaHSO3 和Na2 SO3 (二者分子比为 1∶3)对大鼠海马CA1区神经元瞬间外向钾电流 (IA)和延迟整流钾电流 (IK)的影响。结果表明 ,SO2 代谢衍生物可显著增大IA 和IK,且呈剂量依赖性关系 ,使IA 和IK 增大 5 0 %的剂量分别为 2 6 19μmol/L和 14 5 0 μmol/L。此外还与电压呈依赖性关系 ,但不具有频率依赖性。结果还表明 ,10 μmol/LSO2 代谢衍生物不影响IA 的激活过程 ,而对IK 的激活过程有非常显著的影响 ,给药前后IK 的半数激活电压分别为 17 6 4± 7 31mV和 13 43± 2 0 0mV (n=10 ,P <0 0 1) ,但不改变其斜率因子。另外 ,10 μmol/LSO2 代谢衍生物还非常显著地影响IA 的失活过程 ,给药前后其半数失活电压分别为 - 6 5 93± 1 97mV和 - 5 9 2 2± 3 83mV (n =10 ,P <0 0 1) ,但不改变其斜率因子。由此推断 ,SO2 代谢衍生物增大大鼠海马CA1区神经元的IA 和IK,促进IK 的激活过程 ,并抑制IA 的失活过程 ,可导致胞内K+ 通过K+ 通道的外流增加 ,胞内K+ 浓度降低 ,造成中枢神经元功能紊乱 ,诱导神经细胞凋亡。这意味着SO2 代谢衍生物对中枢神经系统具有损伤作用 ,从而提示大气SO2 污染可能与一些中枢神经系统疾病的发生以及衰老有关 [动物学报 49(1)

大鼠海马CA_1区神经元对电刺激下丘脑腹内侧核的反应

以细胞外玻璃微电极技术记录海马ＣＡ１区神经元的单位放电，观察电刺激下丘脑腹内侧核（ＶＭＨ）时ＣＡ１区神经元的反应。结果发现，刺激ＶＭＨ时，可在６７．８％的ＣＡ１神经元记录到场电位，其峰潜伏期为（１７．９±８．４）ｍｓ，（范围：１０～３５ｍｓ），时程（３０．９±１２．３）ｍｓ，（范围：１５～５５ｍｓ）。约７０％的ＣＡ１神经元（２４／３４）的自发放电频率在刺激ＶＭＨ后发生变化，表现为兴奋，兴奋后抑制及兴奋－抑制－兴奋序列和抑制反应，其余３０％（１０／３４）在刺激前后自发放电频率变化不明显。结果表明，兴奋ＶＭＨ可影响ＣＡ１神经元的电活动，而且影响方式多种多样。

Effects of diazepam on glutamatergic synaptic transmission in the hippocampal CA1 area of rats with traumatic brain injury

The activity of the Schaffer collaterals of hippocampal CA3 neurons and hippocampal CA1 neurons has been shown to increase after lfuid percussion injury. Diazepam can inhibit the hy-perexcitability of rat hippocampal neurons after injury, but the mechanism by which it affects excitatory synaptic transmission remains poorly understood. Our results showed that diazepam treatment signiifcantly increased the slope of input-output curves in rat neurons after lfuid per-cussion injury. Diazepam signiifcantly decreased the numbers of spikes evoked by super stimuli in the presence of 15 μmol/L bicuculline, indicating the existence of inhibitory pathways in the injured rat hippocampus. Diazepam effectively increased the paired-pulse facilitation ratio in the hippocampal CA1 region following fluid percussion injury, reduced miniature excitatory postsynaptic potentials, decreased action-potential-dependent glutamine release, and reversed spontaneous glutamine release. These data suggest that diazepam could decrease the lfuid per-cussion injury-induced enhancement of excitatory synaptic transmission in the rat hippocampal CA1 area.

CEA、CYFRA21-1、NSE、CA125联合检测在肺癌诊断中的应用效果

目的综合分析CEA(血清癌胚抗原)、CYFRA21-1(细胞角蛋白19片段)、NSE(神经元特异性烯醇化酶)、CA125(糖类抗原125)联合检测在肺癌诊断中的应用效果。方法选取180例肺癌(60例鳞癌、60例腺癌、60例小细胞癌)患者临床资料作为研究组,再选取同期60例健康志愿者作为对照组。采用电化学发光法检测研究对象的血清癌胚抗原水平、细胞角蛋白19片段水平、神经元特异性烯醇化酶水平、糖类抗原125水平以及分析4种肿瘤标志物联合检测肺癌的敏感性、特异性等参数指标。结果 (1)研究组的血清癌胚抗原水平、细胞角蛋白19片段水平、神经元特异性烯醇化酶水平、糖类抗原125水平与对照组比较,差异有统计学意义(P<0.05)。(2)腺癌组与鳞癌组、小细胞肺癌组血清癌胚抗原水平比较,差异有统计学意义(P<0.05);鳞癌组与小细胞癌、腺癌组细胞角蛋白19片段水平比较,差异有统计学意义(P<0.05);小细胞癌组与鳞癌组、腺癌组神经元特异性烯醇化酶水平比较,差异有统计学意义(P<0.05)。(3)研究组Ⅲ~Ⅳ期患者CEA、CYFRA21-1、NSE、CA125水平均显著高于Ⅰ~Ⅱ期患者(P<0.05)。(4)4种肿瘤标志物联合检测肺癌的敏感性远远高于任何一种肿瘤标志物的单项检测(P<0.05)。结论 4种肿瘤标志物联合检测在肺癌诊断和临床分期中有一定价值。血清癌胚抗原对肺腺癌、细胞角蛋白19片段对肺鳞癌,神经元特异性烯醇化酶对肺小细胞癌的诊断价值比较高。

海马CA_l区神经元选择易损性组织结构机制的研究

目的 研究海马 CAl 区神经元选择易损性与此区组织结构特点的关系。方法 用透射电子显微镜观察缺血再灌注 12 h、2 4 h、36 h、4 8h、72 h组 CAl 区神经元损伤及星形胶质细胞动态变化。结果 在再灌注各组中 ,星形胶质细胞的超微结构变化早于与之相连的神经细胞 ,而和不与之相连的神经细胞超微结构变化同步。神经元轴突内超微结构变化早于胞内结构。结论 星形胶质细胞对缺血再灌注损伤具有保护作用。海马 CAl

MDGA2 Constrains Glutamatergic Inputs Selectively onto CA1 Pyramidal Neurons to Optimize Neural Circuits for Plasticity,Memory,and Social Behavior

Synapse organizers are essential for the development,transmission,and plasticity of synapses.Acting as rare synapse suppressors,the MAM domain containing glycosylphosphatidylinositol anchor(MDGA)proteins contributes to synapse organization by inhibiting the formation of the synaptogenic neuroligin-neurexin complex.A previous analysis of MDGA2 mice lacking a single copy of Mdga2 revealed upregulated glutamatergic synapses and behaviors consistent with autism.However,MDGA2 is expressed in diverse cell types and is localized to both excitatory and inhibitory synapses.Differentiating the network versus cell-specific effects of MDGA2 loss-of-function requires a cell-type and brain region-selective strategy.To address this,we generated mice harboring a conditional knockout of Mdga2 restricted to CA1 pyramidal neurons.Here we report that MDGA2 suppresses the density and function of excitatory synapses selectively on pyramidal neurons in the mature hippocampus.Conditional deletion of Mdga2 in CA1 pyramidal neurons of adult mice upregulated miniature and spontaneous excitatory postsynaptic potentials,vesicular glutamate transporter 1 intensity,and neuronal excitability.These effects were limited to glutamatergic synapses as no changes were detected in miniature and spontaneous inhibitory postsynaptic potential properties or vesicular GABA transporter intensity.Functionally,evoked basal synaptic transmission and AMPAR receptor currents were enhanced at glutamatergic inputs.At a behavioral level,memory appeared to be compromised in Mdga2 cKO mice as both novel object recognition and contextual fear conditioning performance were impaired,consistent with deficits in long-term potentiation in the CA3-CA1 pathway.Social affiliation,a behavioral analog of social deficits in autism,was similarly compromised.These results demonstrate that MDGA2 confines the properties of excitatory synapses to CA1 neurons in mature hippocampal circuits,thereby optimizing this network for plasticity,cognition,and social behaviors.

Monocarboxylate transporter 4 plays a significant role in the neuroprotective mechanism of ischemic preconditioning in transient cerebral ischemia

Monocarboxylate transporters（MCTs）, which carry monocarboxylates such as lactate across biological membranes, have been associated with cerebral ischemia/reperfusion process. In this study, we studied the effect of ischemic preconditioning（IPC） on MCT4 immunoreactivity after 5 minutes of transient cerebral ischemia in the gerbil. Animals were randomly designated to four groups（sham-operated group, ischemia only group, IPC ＋ sham-operated group and IPC ＋ ischemia group）. A serious loss of neuron was found in the stratum pyramidale of the hippocampal CA1 region（CA1）, not CA2/3, of the ischemia-only group at 5 days post-ischemia; however, in the IPC ＋ ischemia groups, neurons in the stratum pyramidale of the CA1 were well protected. Weak MCT4 immunoreactivity was found in the stratum pyramidale of the CA1 in the sham-operated group. MCT4 immunoreactivity in the stratum pyramidale began to decrease at 2 days post-ischemia and was hardly detected at 5 days post-ischemia; at this time point, MCT4 immunoreactivity was newly expressed in astrocytes. In the IPC ＋ sham-operated group, MCT4 immunoreactivity in the stratum pyramidale of the CA1 was increased compared with the sham-operated group, and, in the IPC ＋ ischemia group, MCT4 immunoreactivity was also increased in the stratum pyramidale compared with the ischemia only group. Briefly, present findings show that IPC apparently protected CA1 pyramidal neurons and increased or maintained MCT4 expression in the stratum pyramidale of the CA1 after transient cerebral ischemia. Our findings suggest that MCT4 appears to play a significant role in the neuroprotective mechanism of IPC in the gerbil with transient cerebral ischemia.

Triggering Receptor Expressed on Myeloid Cells 2 Alleviated Sevoflurane-Induced Developmental Neurotoxicity via Microglial Pruning of Dendritic Spines in the CA1 Region of the Hippocampus

Sevoflurane induces developmental neurotoxicity in mice;however,the underlying mechanisms remain unclear.Triggering receptor expressed on myeloid cells 2(TREM2)is essential for microglia-mediated synaptic refinement during the early stages of brain development.We explored the effects of TREM2 on dendritic spine pruning during sevoflurane-induced developmental neurotoxicity in mice.Mice were anaesthetized with sevoflurane on postnatal days 6,8,and 10.Behavioral performance was assessed using the open field test and Morris water maze test.Genetic knockdown of TREM2 and overexpression of TREM2 by stereotaxic injection were used for mechanistic experiments.Western blotting,immunofluorescence,electron microscopy,three-dimensional reconstruction,Golgi staining,and whole-cell patch-clamp recordings were performed.Sevoflurane exposures upregulated the protein expression of TREM2,increased microglia-mediated pruning of dendritic spines,and reduced synaptic multiplicity and excitability of CA1 neurons.TREM2 genetic knockdown significantly decreased dendritic spine pruning,and partially aggravated neuronal morphological abnormalities and cognitive impairments in sevoflurane-treated mice.In contrast,TREM2 overexpression enhanced microglia-mediated pruning of dendritic spines and rescued neuronal morphological abnormalities and cognitive dysfunction.TREM2 exerts a protective role against neurocognitive impairments in mice after neonatal exposures to sevoflurane by enhancing microglia-mediated pruning of dendritic spines in CA1 neurons.This provides a potential therapeutic target in the prevention of sevoflurane-induced developmental neurotoxicity.

Activation of extrasynaptic GABA_A receptors inhibits cyclothiazideinduced epileptiform activity in hippocampal CA1 neurons

Extrasynaptic GABAA receptors （GABAARs）-mediated tonic inhibition is reported to involve in the patho- genesis of epilepsy. In this study, we used cyclo- thiazide （CTZ）-induced in vitro brain slice seizure model to explore the effect of selective activation of extrasynaptic GABAARS by 4,5,6,7-tetra- hydroisoxazolo[5,4-c] pyridine-3-ol （THIP） on the CTZ-induced epileptiform activity in hippocampal neurons. Perfusion with CTZ dose-dependently induced multiple epileptiform peaks of evoked population spikes （PSs）in CA1 pyramidal neurons, and treatment with THIP （5 μmol/L） significantly reduced the multiple PS peaks induced by CTZ stimulation. Western blot showed that the 6-subunit of the GABAAR, an extrasynaptic specific GABAAR subunit, was also significantly down-regulated in the cell membrane 2 h after CTZ treatment. Our results suggest that the CTZ-induced epileptiform activity in hippocampal CA1 neurons is suppressed by the activation of extrasynaptic GABAARs, and further support the hypothesis that tonic inhibition mediated by extrasynaptic GABAARs plays a prominent role in seizure generation.

蕨麻正丁醇部位对大鼠海马神经元缺氧致钙超载的抑制作用

目的细胞内钙超载被认为是诱发神经元变性和死亡的关键因素。文中研究蕨麻正丁醇部位(n-butanol extract of Potentilla anserina L,NP)对大鼠海马神经元急性缺氧所致钙超载的抑制作用。方法采用体外原代培养的海马神经元建立缺氧所致钙超载的实验模型,分为正常对照组、缺氧模型组、尼莫地平干预组以及NP高、中、低剂量干预组。通过免疫荧光双染观察蕨麻正丁醇部位对海马神经元急性缺氧所致微管相关蛋白2(microtuble-associated protein2,MAP2)的保护作用。利用荧光分光光度计检测各组细胞内游离钙离子浓度([Ca2+]i)。通过半定量RT-PCR、免疫细胞化学染色及Western blot技术检测各组钙依赖中性蛋白酶1(Calpain 1)在基因及蛋白质水平的表达差异。结果缺氧3 h模型组与正常组相比较,神经元特异性细胞骨架蛋白MAP2被水解,细胞骨架形态的被破坏,[Ca2+]i显著升高,Calpain 1在基因和蛋白水平的表达量明显增加,细胞骨架发生破坏。NP各剂量干预明显抑制神经元特异性细胞骨架蛋白MAP2水解,减轻细胞骨架形态的破坏,且显著降低缺氧神经元[Ca2+]i(P<0.05);并且下调了Calpain 1在基因和蛋白的表达水平(P<0.05)。结论急性缺氧3 h可使神经元细胞内发生钙超载,NP可有效抑制缺氧所致神经元细胞钙超载,而发挥神经元作用。

海马不同区域缺血时损伤和hsp70mRNA表达差异

目的 :探讨缺血再灌注后鼠脑海马CA1 区选择性易损伤和迟发神经元死亡现象,以及hsp70mRNA差异表达的可能机制。方法 :观察鼠前脑缺血再灌注时 ,海马CA1 区、CA3 区及齿状回锥体细胞在组织学变化 ;以及原位杂交技术检测各区hsp70mRNA的诱导表达。结果:缺血再灌注7d后海马CA1 区锥体细胞缺失明显,而CA3 区及齿状回未见明显形态学变化。CA1 区hsp70mRNA的诱导较其余两区迟,而持续时间较长。结论:在缺血早期加强或在缺血后期抑制hsp70mRNA的诱导,有可能保护CA1 区锥体细胞。

电针对缺氧缺血性脑病幼鼠学习记忆能力的影响

目的:观察电针对缺氧缺血性脑病幼鼠学习记忆能力的影响,探讨电针对其神经元的作用机制。方法:将7d龄SD大鼠随机分为假手术组(n=12)、模型组(n=11)和电针组(n=12)。采用左颈总动脉结扎联合缺氧的方法建立缺氧缺血性脑病模型。电针组予电针"百会""大椎",隔日1次,每次20min,连续28d。观察治疗后幼鼠转棒跌落潜伏期、高架迷宫进入开放臂时间、水迷宫逃避潜伏期和逃避距离,高尔基染色法观察幼鼠神经元树突棘的密度。结果:转棒跌落潜伏期和高架迷宫进入开放臂时间,3组之间差异无统计学意义(P>0.05)。水迷宫实验,模型组较假手术组逃避潜伏期延长(P<0.05),逃避距离增加(P<0.05),平台象限停留时间减少(P<0.05),原平台穿越次数减少(P<0.05);电针组较模型组逃避潜伏期缩短(P<0.05),逃避距离减少(P<0.05),平台象限停留时间增加(P<0.05),原平台穿越次数增加(P<0.05)。模型组较假手术组树突棘密度降低(P<0.05),电针组较模型组树突棘密度升高(P<0.05)。结论:电针可以改善幼鼠缺氧缺血造成的学习记忆能力损伤,其作用可能与调节神经元树突棘密度有关。