牛蛙交感神经节胆碱能传递的实验观察

使用常规细胞内记录技术,记录和分析牛蛙第Ｘ交感神经节Ｂ细胞突触传递过程发生的动作电位、快兴奋性一电位、慢抑制性突后电位和慢兴奋性一电位,研究其胆碱能生与细胞兴奋性的关系在触传递过程中复杂的整合关系。     

皮质醇对牛蛙交感神经节B细胞电生理特性及突触传递的快速作用

在离体灌流的７２只牛蛙交感神经节标本上，电刺激节前纤维，细胞内记录Ｂ细胞的电活动。观察皮质醇对Ｂ细胞的电生理学特性和突触传递的快速作用。２９个Ｂ细胞，给予１μｍｏｌ／Ｌ皮质醇后，静息电位、动作电位振幅和超射值及膜时间常数均无明显变化，但输入阻抗增加和膜电容减少却变化明显；电刺激节前纤维，细胞内记录１８３个Ｂ细胞的动作电位，给予皮质醇０５～３ｍｉｎ，部分Ｂ细胞的突触传递发生脱漏甚至完全阻断，有明显的量效关系。上述结果提示，皮质醇对牛蛙交感神经节Ｂ细胞的突触传递具有快速阻断作用，这种作用不经基因组机制，可能是皮质醇通过Ｎ受体介导而引起。也提示在应激反应时，皮质醇可能快速调制交感神经系统的功能，参与牛蛙交感神经节的局部负反馈调节     

谷氨酸受体与神经退行性疾病

谷氨酸是哺乳动物中枢神经系统中最重要的兴奋性神经递质,主要在谷氨酸受体的介导下实现其在脑内的众多功能.谷氨酸受体被激活后除参与快速的兴奋性突触传递外,还可以调节神经递质的释放、突触的可塑性、学习和记忆以及突触长时程增强和长时程抑制等中枢神经系统正常的生理功能[1].     

医药常识

1.什么是神经递质？ 神经递质是指神经末梢释放的、作用于突触后膜受体、导致离子通道开放并形成兴奋性突触后电位或抑制性突触后电位的化学物质。其特点是传递信息快,作用强,选择性高。神经递质的功能是把信息从突触前神经元传递到突触后神经元。神经元是中枢神经系统的基本结构和功能单位,其最主要的功能是传递信息。神经元之间或神经元与效应细胞之间的信息传递往往通过突触进行。     

大鼠视皮层两类神经元的NMDA及GABAA受体介导的突触后电流电学特性研究

目的 在视觉发育可塑性关键期内,探讨大鼠视皮层神经元的细胞类型与兴奋性和抑制性突触后反应的关系.方法 对出生后14～28 d龄正常大鼠进行视皮层脑片膜片钳全细胞记录,分别采用神经药理学方法分离和记录谷氨酸和N-甲基-D-天冬氨酸(N-methyl-D-aspartate,NMDA)受体介导的兴奋性突触后电流(excitatory postsynaptic currents, EPSCs)以及γ-氨基丁酸(galnma-aminobutyric acid,GABAA)受体介导的抑制性突触后电流(inhibitory postsynaptic currents,IPSCs),并进行神经元细胞内标记、免疫细胞化学染色.结果 锥体细胞和颗粒细胞的NMDA受体介导的EPSCs峰值、上升时间、下降时间及NMDA/谷氨酸电流比率并无显著性差异(P＞0.05);锥体细胞GABAA受体介导的IPSCs下降时间较颗粒细胞的短(P＜0.05),而峰值和上升时间并无显著性差异(P＞0.05).结论 在视觉发育可塑性关键期内,GABAA受体在大鼠视皮层不同神经元的突触传递中可能发挥不同的作用,而NMDA受体在不同神经元的突触传递中具有同质性.     

离体脊髓同侧中央管周围区电刺激诱发运动神经元突触反应

目的：探讨新生大鼠脊髓切片同侧中央管周围区（iPCC）向运动神经元（MN）兴奋性突触传递的细胞电生理特性。方法：应用新生大鼠（8～14 d）脊髓切片MN细胞内记录技术,观察iPCC局部电刺激在MN所诱发的突触反应。结果：在14个测试的MN,观察到iPCC电刺激可在11个MN上诱发兴奋性突触后电位（iPCC-EPSP）,在1个MN上诱发抑制性突触后电位（ iPCC-IPSP ）,在2个 MN上诱发iPCC-EPSP后复合有iPCC-IPSP的反应。 iPCC-EPSP不仅具有刺激强度依赖性和膜电位依赖性,而且可以被低钙高镁溶液或TTX（0．1μmol/L）可逆性取消。荷包牡丹碱和士的宁能增大iPCC-EPSP,但谷氨酸受体拮抗剂 APV（30μmol/L）和DNQX（1μmol/L）仅部分抑制iPCC-EPSP。结论：iPCC的激活可通过兴奋性突触传递调制MN的活动,其介导递质除谷氨酸外,可能还有其他递质的参与。     

N-甲基D-氨基天氡氨酸受体与学习记忆关系的研究进展

N-甲基D-氨基天氡氨酸受体(NMDAR)是兴奋性氨基酸谷氨酸的一类特异性受体，通过在突触水平加强突触前后神经元的联合兴奋来加强长时程增强效应。它是非常重要的突触后成分，不但可诱导出兴奋依赖性的突触可塑性，还在细胞间的信息传递中发挥着重要的介导作用。本文对近年来NMDAR与学习记忆关系的研究进展作一综述。     

N-甲基-D-天冬氨酸受体介导的学习记忆及神经毒性的研究进展

N-甲基-D-天冬氨酸受体(N-methyl-D-aspartic acid receptor,NMDAR)是一种谷氨酸能兴奋性神经受体,由多种亚基组成强制性异四聚体。NMDAR的兴奋性谷氨酸能神经传递对于神经元的突触可塑性和神经细胞的存活至关重要。海马体和纹状体的突触可塑性与学习记忆的关系密切,其中,海绵体的突触可塑性的原型形式长时程增强(long-term potentiation,LTP)参与学习记忆的维持和巩固,而纹状体的突触可塑性是构成学习和记忆的细胞基础。生理状态下的NMDAR的各个亚基可对学习记忆的产生起促进作用。然而,NMDAR亚基的过度激活,则会引起学习记忆障碍及诱导兴奋性神经毒性并促进神经细胞死亡。此外,突触内NMDAR的正常激活启动突触可塑性并刺激细胞存活。相反,突触外NMDAR的过度激活可诱导Ca2+超载,介导兴奋性神经毒性并促进神经细胞死亡;但是,目前越来越多的研究表明,突触内NMDAR在促进神经元存活的同时,同样可以介导兴奋性神经毒性从而引起神经细胞死亡。主流观点认为兴奋性神经毒性主要由Ca2+超载介导,部分观点则认为NMDAR还可以通过Ca2+超载与非离子通道同时介导兴奋性神经毒性。本文主要就NMDAR对学习记忆促进及抑制作用及其诱导的兴奋性神经毒性的研究进展进行综述。      

三种阿片受体激动剂对突触传递的抑制作用

三种阿片受体激动剂对突触传递的抑制作用袁孝如中国药理学报１９９６，１７（３）∶２７８目的：比较不同浓度三种阿片受体激动剂对突触传递的抑制作用。方法：用细胞内记录和细胞外微电泳技术，于大鼠伏核脑片制备上记录神经元的兴奋性突触后电位和谷氨酸钠所致细胞膜去...     

对侧腹外侧索电刺激在新生大鼠脊髓切片运动神经元诱发的突触反应

目的:探讨对侧腹外侧索(cVLF)下行激活对离体脊髓运动神经元(MN)活动的突触调制作用。方法:应用新生大鼠(8~14 d)脊髓切片MN细胞内记录技术,观察cVLF或同侧VLF(iVLF)电刺激在MN所诱发的突触反应。结果:在32个测试的MNs,观察到cVLF电刺激可在21个MNs上诱发去极化反应(即cVLF性兴奋性突触后电位,cVLF-EPSP),在1个MN上诱发超极化反应(即cVLF性抑制性突触后电位,cVLF-IPSP),在4个MNs上诱发cVLF-EPSP后复合有cVLF-IPSP的反应。cVLF-EPSP具有刺激强度依赖性、被低钙高镁溶液取消的特性,与i VLF性EPSP相比,有潜伏期较长的特点(P<0.001)。cVLF-IPSP呈膜电位依赖性,并被印防己毒素(30μmol/L)及士的宁(1.0μmol/L)取消。结论:cVLF的下行激活可通过兴奋性和抑制性突触传递调制MN的活动,其cVLF-IPSP可能由γ-氨基丁酸A受体和(或)甘氨酸受体介导。     

毒蕈碱乙酰胆碱M2/M4受体亚型在调节脊髓背角神经元谷氨酸能递质释放中的作用

目的研究毒蕈碱胆碱能受体（mAChRs）亚型对脊髓背角感觉神经元谷氨酸能突触传递的调节机制。方法在急性切取
的腰段脊髓切片上,利用全细胞膜片钳法记录mAChRs非特异性激动剂氢化震颤素M（Oxo-M）对脊髓背角浅层神经元谷氨酸
能兴奋性突触后电流（eEPSCs）的影响,给予M2/M4受体特异性拮抗剂喜巴辛,观察mAChRs在脊髓背角浅层神经元谷氨酸能
递质释放调节过程中的作用。结果不同浓度Oxo-M使脊髓背角神经元单突触和多突触eEPSCs的幅度显著降低,其抑制强度
呈浓度依赖性,喜巴辛可以拮抗Oxo-M对刺激诱发eEPSCs幅度的抑制作用,在记录的25个细胞中,92.3%的单突触细胞和75%
的多突触细胞表现为Oxo-M抑制作用被完全拮抗,另有16%的细胞表现为部分拮抗作用。结论mAChRs激活后通过位于脊髓
背角传入神经末梢突触前膜的M2或M4受体亚型抑制兴奋性谷氨酸递质的释放,这种突触前对谷氨酸释放的调节可能是胆碱
能系统和mAChRs在脊髓水平对伤害性刺激调控的作用机制。
     

Effects of milnacipran on the inhibitory postsynaptic potential in neurons of the rat locus coeruleus

Effects of milnacipran (MIL), a serotonin and noradrenaline reuptake inhibitor (SNRI), on synaptic transmission were examined in the rat locus coeruleus (LC). Bath-application of MIL produced a hyperpolarization associated with a decrease in input resistance of LC neurons. The MIL-induced hyperpolarization reversed polarity near the equilibrium potential of K+. The MIL-induced hyperpolarization was blocked by yohimbine (1 microM). Clonidine, but not serotonin (5-hydroxytryptamine; 5-HT), produced a hyperpolarizing potential in LC neurons. The MIL-induced hyperpolarization reversed polarity at -114 +/- 3 mV (n=4). MIL (0.1-10 microM) depressed the amplitude of the excitatory postsynaptic potential (EPSP), while it enhanced the amplitude and duration of the inhibitory postsynaptic potential (IPSP). These results suggest that MIL hyperpolarizes LC neurons and enhances the IPSP by increasing endogenous noradrenaline (NA) concentration at synapses in LC neurons.     

Methylphenidate enhances inhibitory synaptic transmission by increasing the content of norepinephrine in the locus coeruleus of juvenile rats

The present study examined the effect of methylphenidate (MPH), a psychostimulant, on nor-adrenergic transmission in the locus coeruleus (LC) of juvenile rats. Intracellular recordings showed that MPH (>3 μM) produced a hyperpolarizing response associated with a decrease in the rate of spontaneously firing action potentials. MPH (1 μM) enhanced the amplitude of the inhibitory postsynaptic potential (IPSP) mediated by norepinephrine (NE), but did not change the excitatory postsynaptic potential (EPSP) mediated by excitatory amino acids. Whole-cell patch-clamp recordings showed that MPH (0.3-30 μM) produced an outward current (I(MPH)) and enhanced the inhibitory postsynaptic current (IPSC) in neurons of the juvenile rat LC. MPH (30 μM) enhanced the NE-induced outward current (I(NE)). Bath-application of yohimbine (1 μM) produced an inward current and blocked the MPH-induced enhancement of the IPSC. Yohimbine (1 μM) depressed not only the I(NE) but also the I(MPH) in juvenile rat LC neurons. The current-voltage relationship of the I(MPH) showed inward rectification and reversed polarity at -91.1±4.3 mV (n=5). Ba(2+) (100 μM) blocked the I(MPH), indicating that the I(MPH) is mediated by Ba(2+)-sensitive inward rectifier K(+) current. These results suggest that MPH enhances inhibitory synaptic transmission by increasing the concentration of NE at noradrenergic synapses in juvenile rat LC neurons.     

Effects of adenosine and ATP on the membrane potential and synaptic transmission in neurons of the rat locus coeruleus

Effects of adenosine (Ado) and adenosine 5'-triphosphate (ATP) on the membrane potential and synaptic transmission in neurons of the rat locus coeruleus (LC) were examined, in vitro. Ado (30-300 microM) produced a hyperpolarizing response and inhibited spontaneous firing activity in neurons of the rat LC. Ado decreased input resistance of LC neurons. The Ado-induced hyperpolarization reversed polarity near the equilibrium potential of K+ (EK). Ado (100-300 microM) depressed both excitatory postsynaptic potential (EPSP) and inhibitory postsynaptic potential (IPSP). Ado (300 microM) did not alter the hyperpolarization induced by norepinephrine (30 microM). N6-Cyclopentyladenosine (CPA, 100 microM), an A1 receptor agonist, also produced a hyperpolarizing response and depressed both the EPSP and IPSP. Another A1 receptor agonist, adenosine amine congener (ADAC, 30 microM) also produced a hyperpolarizing response and consistently depressed the EPSP and IPSP. Application of ATP (100 microM) to LC neurons caused a depolarizing response associated with an increase in the firing rate of spontaneous action potential in LC neurons. The ATP-induced depolarization was accompanied by an increased input resistance and reversed polarity at--91 mV. ATP (100 microM) consistently depressed the IPSP, while it did not change the amplitude of the EPSP in a majority of neurons. alpha, beta-Methylene ATP (alpha, beta-meATP, 30 micro/M), a P2 receptor agonist, mimicked these effects of ATP. Adenosine 5'-(beta, gamma-imido) triphosphate (AMP-PNP, 100 microM), a non-metabolizable analogue of ATP, produced a depolarizing response in LC neurons, but it produced no obvious depression of the EPSP and IPSP. These results suggest that Ado and ATP cause inhibitory and excitatory modulation, respectively, of neuronal activity and synaptic transmission in the rat LC.     

Effects of methylphenidate on the inhibitory postsynaptic potential in rat locus coeruleus neurons

Effects of methylphenidate (MPH), an agent used clinically for the treatment of children presenting the attention-deficit/hyperactivity disorder (AD/HD), on synaptic transmission in the rat locus coeruleus (LC) were examined by intracellular recording methods. Bath-application of MPH (30 nM-3 microM) increased the amplitude of the inhibitory postsynaptic potential (IPSP), while it did not change the amplitude of the excitatory postsynaptic potential (EPSP). MPH increased the time-to-peak and the half-decay time of the IPSP in LC neurons. MPH increased the amplitude of spontaneous IPSP: individual spontaneous IPSPs merged one into the other so as to produce regular, long-lasting waves of hyperpolarization. Clonidine (10 nM), a selective agonist for alpha 2-adrenoceptors, depressed the IPSP without affecting the EPSP in LC neurons. The results suggest that MPH enhances inhibitory synaptic transmission in the rat LC by depressing the norepinephrine (NE) re-uptake system.     

红藻氨酸对海马CAl区突触传递的作用

OBJECTIVE: To investigate the effect of activated kainate receptor on both the excitatory and inhibitory synaptic transmission in the neurons in the hippocampal CA1 region. METHOD: Blind whole-cell voltage-clamp recordings were performed on the CA1 pyramidal cells in adult rat hippocampal slices to examine and analyze the effect of bath-applied kainate (10 micromol/L) on CA1 afferent fiber-evoked excitatory postsynaptic currents (EPSCs) and inhibitory postsynaptic currents (IPSCs), respectively. RESULTS: Activation of kainate receptor significantly depressed both IPSCs (P <0.01) and EPSCs (P <0.01) in neurons in the hippocampus CA1 region. CONCLUSION: Activation of kainate receptors directly inhibit excitatory and inhibitory input in those neurons, which contributes to the development of epilepsy in the hippocampus by affecting the dynamic balance of the hippocampal neurons.     

酸中毒对小鼠大脑皮层GABA能神经元电生理特性的影响

目的 探讨胞外酸中毒对小鼠大脑皮层γ-氨基丁酸（GABA）能神经元动作电位发放和突触传递功能的影响。方法 选择出生后27～30 d的小鼠20只,做大脑冠状切片,随后分为正常对照组和细胞外酸中毒组:大脑冠状切片灌流pH值为7.4的人工脑脊液,采用膜片钳全细胞电流钳模式记录动作电位阈电位、绝对不应期和动作电位峰间距,电压钳模式记录自发性兴奋性突触后电流,为正常对照组;随后将灌流人工脑脊液的pH值调为6.5,模拟胞外酸中毒,为细胞外酸中毒组。再次记录神经元动作电位和自发性兴奋性突触后电流,比较两组间以上各项指标的差异。结果 与正常对照组对比,胞外酸中毒使GABA能神经元动作电位峰间距和绝对不应期延长（P<0.01）,阈电位升高（P<0.01）,自发性兴奋性突触后电流幅度和频率增加（P<0.01）。结论 胞外酸中毒损伤大脑皮层GABA能神经元动作电位的发放和突触传递,这可能是酸中毒诱导脑功能损伤的机制之一。     

Effects of interleukin-1 beta on neurons in mammalian pelvic ganglia

The effects of interleukin-1 beta (IL-1 beta) on the membrane potential and synaptic transmission were examined in neurons of mammalian pelvic ganglia. Bath-application of recombinant human IL-1 beta (6-300 pM) for 10 s-5 min produced a long-lasting hyperpolarization associated with increased input resistance in 11 neurons of rat major pelvic ganglia (MPG). In other 8 neurons, IL-1 beta (300 pM) produced a biphasic response that consists of an initial depolarization followed by a long-lasting hyperpolarization. IL-1 beta 163-171 (10-100 pM), a synthetic nonapeptide analog that contains the active domain of human IL-1 beta, mimicked the effect of IL-1 beta in MPG neurons. gamma-Aminobutyric acid (GABA, 300 microM) produced a depolarization followed by a hyperpolarization that was blocked by picrotoxin (100 microM). Db-cyclic guanosine monophosphate (db-cyclic GMP, 100 microM) also produced an initial depolarization followed by a long-lasting hyperpolarization. These results suggest that the IL-1 beta-induced biphasic response is mediated by a GABA receptor-cyclic GMP pathway. IL-1 beta and IL-1 beta 163-171 caused an initial facilitation followed by a long-lasting depression of the excitatory postsynaptic potential (EPSP) in rabbit VPG. The data suggest that IL-1 beta presynaptically depressed the EPSP by reducing the release of acetylcholine (ACh) from the pelvic nerve terminals.     

乙酰胆碱甘氨酸及其拮抗剂对大鼠旁巨细胞外侧核神经元自发放电的影响

用多管微电极技术，在麻醉、自主呼吸的大鼠旁巨细胞外侧核尾半侧（ｃＰＧＣＬ）观察了微电泳乙酰胆碱（ＡＣｈ）、甘氨酸（Ｇｌｙ）及其拮抗剂阿托品、士的宁对神经元自发放电的效应及阿托品对ＡＣｈ、士的宁对甘氨酸效应的影响。发现ＡＣｈ可使大多数被测试神经元（７９．６％）兴奋，少数（２０．４％）无反应；甘氨酸可使大多数被测试神经元（９１．５％）抑制，少数（８．５％）无反应；阿托品可使神经元兴奋（占被测试神经元的８％）、抑制（４８％）和无反应（４４％）；士的宁可引起神经元兴奋（２１．９％）、抑制（６．３％）和无反应（７１．８％）。ＡＣｈ的兴奋效应，甘氨酸和阿托品的抑制效应均呈量效依赖关系。阿托品可部分或完全阻断大多数被测试神经元（８０．３％）对ＡＣｈ的兴奋反应；士的宁可阻断大多数被测试神经元（９２．６％）对甘氨酸的抑制反应。以上结果提示，ｃＰＧＣＬ区存在着内源性ＡＣｈ和甘氨酸，某些神经元上存在着Ｍ受体及甘氨酸受体