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.     

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.     

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.     

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.     

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。     

IGF-1对海马神经元抑制性突触传递的影响

目的观察胰岛素样生长因子1(IGF-1)对原代培养海马神经元抑制性突触传递的影响并探讨其可能机制。方法采用无血清培养基培养海马神经元,在10~14d时用于实验。电生理实验分为正常对照组和IGF-1处理组(实验前24h加入IGF-1,终浓度为10μmol/L)。细胞免疫化学实验分为正常对照组、IGF-1处理组和MAPKS转导通路抑制剂(PD98059)预处理组(IGF-1处理前1h加入PD98059,终浓度为10μmol/L)。采用全细胞膜片钳记录方法观察IGF-1对抑制性突触后电流(IPSC)的影响,用细胞免疫化学方法观察其对γ-氨基丁酸能细胞数目影响。结果IGF-1能够显著降低IPSC的频率,但与对照组比较其幅度差异无统计学意义;IGF-1能够明显减少GABA阳性细胞数目,应用PD98059后可阻断这种作用。结论IGF-1的上述作用可能参与海马对学习记忆功能的调节过程。     

阿托品对氢化可的松快速作用的影响

在离体灌注的牛蛙交感神经节上,氢化可的松一方面通过Ｎ受体介导,快速抑制Ｂ细胞的快尖奋性突触后电位,引起Ｂ细胞突触 传递的阻断。氢化可的松的又同时通过Ｍ受体介导,快速增强Ｂ细胞的慢兴奋性突触 后电位,提高Ｂ细胞的兴奋性,使重复放电增加。     

D-丝氨酸对大鼠视皮层神经元突触后NMDA受体功能的调制作用

目的：观察在发育大鼠视皮层脑片标本上D-丝氨酸对大鼠视皮层神经元突触后NMDA受体功能是否具有调制作用．方法：应用脑片膜片钳全细胞记录技术,记录13～15dSD大鼠视皮层Ⅱ-Ⅲ层椎体神经元的微小兴奋性突触后电流（mEPSCs）,观察D-丝氨酸对mEPSCs的调制作用．结果：mEPSCs包含两种受体电流成分,即AMPA受体与NMDA受体电流成分;应用外源性D-丝氨酸（1,10和100μmol／L）均增强了mEPSCs的NMDA受体电流成分（P〈0．01）,并呈现浓度依赖性,而应用NMDA受体阻断剂D—APV（50μmol／L）完全阻断这种增强效应．此外,D-丝氨酸没有影响mEPSCs的AMPA受体电流成分．结论：在大鼠视皮层Ⅱ-Ⅲ层锥体神经元上,突触后NMDA受体的甘氨酸结合位点是不饱和的,应用外源性D-丝氨酸可以增强NMDA受体功能,本研究为精神分裂等精神疾病的治疗提供有意义的资料．     

Inflammation unmasks gabapentin'''' s effect on AS-fiber evoked excitatory postsynaptic currents in substantia gelatinosa neurons of rat spinal cord

Objective To study the analgesic mechanism of gabapentin, an anticonvulsant, during antinociceptive clinical treatment.Methods Whole-cell voltage-clamp recordings were taken from adult rat spinal cord slices to investigate the effect of gabapentin on primary afferent A8-fiber evoked excitatory postsynaptic currents (EPSCs) to substantia gelatinosa (SG) neurons in normal and inflamed (established by plantar injection of carrageenan) rats.Results Gabapentin (5 -20 μmol/L for 5 min) depressed dorsal root A8 fiber evoked polysynaptic, but not monosynaptic EPSCs to SG experiencing inflammation by about 25% (n = 10, P <0. 01). However, gabapentin did not depress the evoked polysynaptic or monosynaptic EPSCs in normal rats. Gabapentin failed to block a glutamate receptor subtype, N-methyl-D-aspartate (NMDA), -induced slow excitatory currents on SG neurons.Conclusions Inflammation, at least in pan", unmasks the gabapentin depression on nociception transmission in the dorsal horn, and this depression is not due     

孤束核神经元α肾上腺素能受体与5-羟色胺能受体的关系

在30个大鼠脑薄片上,共观察了5-HT与NE对57个孤束核神经元单位放电的作用。其中47个对5-HT与NE均有反应,而其中的8个用低钙高镁阻断突触传递后再给5-HT与NE仍有5例有该反应。另外5例对5-HT与NE单独起反应或均无反应的神经元用上述方法阻断突触传递后,有3例对5-HT与NE均有反应,提示在孤束核神经元上自身同时存在着5-HT与α肾上腺素受体。并有少数受其他神经元的抑制。在另外的5个NE与5-HT均兴奋的神经元,同时给NE与5-HT。其中3个转变为抑制;3个对单独用NE与5-HT抑制的神经元合用后,2个变为兴奋。提示在某些孤束核神经元上这两种受体可能存在相互抑制作用。     

NPA抑制大鼠DRG分离神经元ATP-激活电流

目的　本研究主要探讨多巴胺D2受体的选择性激动剂R(- ) -NPA对ATP -激活电流的调制。方法　在大鼠新鲜分离的DRG神经元标本上应用全细胞膜片钳技术 ,观察了NPA对ATP -激活电流的作用。结果　大部分受检细胞 (87.3% ,48/ 5 5 )对ATP敏感 ,10 -6～ 10 -3 mol/LATP可引起剂量依赖性呈明显去敏感的内向电流。在此45个细胞中 ,预加NPA可引起三类反应 :(1)外向电流 (6 .3% ,3/ 48) ;(2 )内向电流 (2 5 .0 % ,12 / 48)和 (3)无反应 (6 8.8% ,33/ 48)。与ATP -激活电流相比 ,NPA -激活电流幅值小 ,无明显去敏感现象。预加NPA 30～ 6 0s对ATP -激活电流的影响如下 :在 91.7% (4 4/ 48)的细胞产生抑制作用 ,其余的无明显作用 (8.3% ,4/ 48)。此种抑制作用与NPA本身是否引起或引起的是内向或外向电流无关。在浓度 10 -7～ 10 -5mol/L范围NPA对 10 -4 mol/LATP -激活电流的抑制作用依赖于NPA的浓度。胞内透析GDP - β -s上述抑制作用可完全被取消。 结论　NPA对ATP -激活电流的抑制作用可能是由于D2受体激活后经G蛋白偶联及相应胞内转导途径而使ATP受体磷酸化所致。     

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

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 CAI neurons 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 -40mV 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.     

5-HT调制离体脊髓运动神经元活动的作用特征

应用新生大鼠脊髓切片运动神经元(MN)细胞内记录技术,观察5-羟色胺(5-HT)对MN活动的影响(n=50)。发现5-HT在78％MN引起伴有膜电导降低的去极化或内向电流,反应在TTX溶液中持续存在,翻转电位在-90～-105mV,为氟苯氧丙胺增强,但被二甲麦角新碱颉颃。5-HT在8％MN诱发超极化反应,但易于失敏。5-HT在40％MN诱导兴奋和(或)抑制性突触活动,分别对犬尿烯酸和士的宁敏感。结果表明5-HT通过直接或间接方式对MN活动产生兴奋或抑制性调制作用。     

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。
     

Adenosine inhibits a GABAB receptor-mediated hyperpolarizing postsynaptic potential in neurons of rat septal nuclei

Intracellular recordings were made from neurons of rat dorsolateral septal nucleus (DLSN), in vitro. Adenosine and 2-chloroadenosine (1-500 microM) hyperpolarized DLSN neurons and blocked the excitatory postsynaptic potential (EPSP) and the late hyperpolarizing potential (LHP) in the presence of bicuculline. Adenosine did not depress the glutamate-induced potential. Bath-application of adenosine depressed the baclofen-induced potential in 60% of the neurons. Adenosine also inhibited the LHP in the remaining 40% of neurons, while it did not depress the baclofen-induced potential in these neurons. These results indicate that adenosine inhibits the EPSP pre-synaptically whereas it inhibits the LHP both pre- and postsynaptically in rat septal nuclei.     

姜黄素对离体培养大鼠海马神经元突触传递的影响

目的 探讨姜黄素对离体培养的大鼠海马神经元突触传递的影响.方法 离体培养胚胎18 d SD大鼠海马神经元,9 d后加入姜黄素(终浓度10 μmol/L),继续培养24 h,采用全细胞膜片钳技术,自由记录模式,观察姜黄素对海马神经元自发兴奋性突触后电流(sEPSC)和微小兴奋性突触后电流(mEPSC)频率和幅度的影响.结果 (1)姜黄素干预的海马神经元sEPSC频率(1.4 Hz±0.5 Hz)明显高于对照组(0.8 Hz±0.4 Hz,P＜0.01);但姜黄素组海马神经元sEPSC幅度(1834 pA±244 pA)和对照组海马神经元sEPSC幅度(1721 pA±391 pA)比较差异没有统计学意义(P=0.115).(2)姜黄素干预的海马神经元mEPSC频率(6.4 Hz±0.8 Hz)明显高于对照组(5.1 Hz±0.9 Hz,P＜0.01);但姜黄素组神经元mEPSC幅度(34 pA±10 pA)和对照组海马神经元mEPSC幅度(30 pA±9pA)比较差异没有统计学意SL(P=0.057).结论 姜黄素可以增强海马神经元突触传递,这可以为最近研究发现姜黄素具有缓解脑缺血、改善AD大鼠认知功能提供神经电生理学依据.     

SKF38393抑制大鼠DRG分离神经元ATP-激活电流

目的 :探讨多巴胺D1受体的选择性激动剂SKF3 83 93HCl对ATP -激活电流的作用。方法 :在大鼠新鲜分离的DRG神经元标本上应用全细胞膜片钳技术 ,记录SKF3 83 93对ATP -激活电流的作用。结果 :大部分受检细胞 ( 87.5% ,77/ 88)对ATP敏感 ,10 - 6 ～ 10 - 3 mol/LATP可引起剂量依赖性呈明显去敏感的内向电流。在此77个细胞中 ,预加SKF3 83 93可引起三类反应 :①外向电流 ( 7.8% ,6/ 77) ;②内向电流 ( 2 6.0 % ,2 0 / 77) ;③无反应( 66.2 % ,51/ 77)。与ATP -激活电流相比 ,SKF3 83 93 -激活电流幅值小 ,无明显去敏感现象。预加SKF3 83 93 3 0～ 60s对ATP -激活电流的影响如下 :在 74.0 % ( 57/ 77)的细胞产生抑制作用 ,15.6% ( 12 / 77)的细胞产生增强作用 ,其余的无明显作用 ( 10 .4% ,8/ 77) ,本文主要针对此抑制作用进行探讨。此种抑制作用与SKF3 83 93本身是否引起或引起的是内向或外向电流无关。在浓度 10 - 9～ 10 - 4mol/L范围SKF3 83 93对 10 - 4mol/LATP -激活电流的抑制作用依赖于SKF3 83 93的浓度。胞内透析H 7上述抑制作用可完全被取消 ,而胞内透析H9此抑制作用依旧存在。结论 :SKF3 83 93对ATP -激活电流的抑制作用可能是由于D1受体激活后经G蛋白偶联及PKC途径使ATP受体磷酸化所致。     

依托咪酯对大鼠海马 CA1区神经元突触结构电流-电压曲线的离子通道机制研究

目的：探讨静脉麻醉药物依托咪酯对大鼠海马 CA1区兴奋性突触后电流（excitatory postsynaptic cur-rents,EPSCs）的电流-电压（I-V）曲线在离子通道层面的影响机制。方法采用断头法分离 Wistar 大鼠海马脑半球,运用切片机制作400μm 厚度的海马脑部切片。切片分别置于60μL 脂肪乳剂和依托咪酯（相当于10μmol/L）乳剂中孵育40 min。在 Schaeffer 侧支/联合纤维处给予单个刺激,同时改变 CA1锥体神经元细胞膜钳制电位（-100～＋40 mV 时,变化幅度为20 mV）,绘制 I-V 曲线,并且采用膜片钳内面向外式记录技术全程记录外向整流特性的单通道氯电流。结果在保持膜钳制电位-70 mV 的条件下,10μmol/L 的依托咪酯降低反转电位,其电位由-53 mV 左右降低为-60 mV 左右,I-V 曲线左移,相应的单通道氯电流明显增强,通道开放程度增加。结论在静息状态下,依托咪酯主要作用于兴奋性突触后膜 GABAA 受体,通过使其 EPSCs 的离子构成发生变化抑制兴奋性突触活动,此过程中外向的电流分量增加,发生的主要改变可能为氯离子的跨膜转运。     

小鼠初级听皮层SOM中间神经元突触输入的时空特性研究

目的 研究小鼠初级听皮层SOM+神经元接受刺激后突触输入的时空特性.方法 通过局部场电位记录方法对初级听皮层进行定位后,采用电压钳全细胞记录方法在离体脑片上分别记录SOM+神经元和锥体神经元在接受刺激后诱发的兴奋后突触后电流和抑制性突触后电流.通过对两类神经元的兴奋性突触后电流和抑制性突触后电流时间特性以及幅度上的比较,从而分析SOM+神经元突触输入的时空特性.结果 SOM+神经元与锥体神经元的突触输入在时间特性上表现出相似的起始潜伏期.SOM+神经元的兴奋性突触后电流和抑制性突触后电流的峰值潜伏期[(14.35 ±2.74) ms,(18.26 ±3.24) ms]明显要短于锥体神经元的兴奋性突触后电流和抑制性突触后电流的峰值潜伏期[(18.81 ±3.76) ms,(21.08 ±3.93)ms],差异具有统计学意义(EPSC P＜0.05,IPSC P＜0.01).在突触后电流的幅度上两类神经元差异没有统计学意义(P＞0.05).结论 SOM+中间神经元接受的突触输入与锥体神经元接受的突触输入在基本电生理特性上类似,但时间特性上的差异提示两者接受的突触输入在皮层内环路来源上可能存在一定差异.     

吗啡通过突触前机制抑制视上核神经元兴奋性突触传递

目的：研究吗啡对大鼠视上核神经元兴奋性突触后电流（excitatory postsynaptic currents,EPSCs）的影响,并对其突触机制进行探讨,方法采用脑片膜片钳全细胞记录技术,在电压钳状态下,记录吗啡对大鼠视上核神经元EPSCs和mEPSCs(miniature EPSCs)的影响。结果20μmol.L^-1的吗啡可分别使大鼠视上核神经元的EPSCs的频率下降65％,幅度养活,mEPSCs频率下降45％,幅度减少12％,结论吗啡通过突触前机制抑制视上核神经元突触前兴奋性递质的传递。