猫中·间脑结合部神经元与眼球下斜肌运动神经元的直接突触联系

本文应用神经元自发放电触发的迭加平均法,研究了猫中·间脑结合部内侧区神经元与眼球下斜肌运动神经元（inferiorobliquemotoneurons,IOMNs）之间的突触联系。电刺激同侧或对侧中·间脑结合部的Forel'sfieldeH（FFH）的内侧区（A7～Ag）,在IOMN池内记录到兴奋性单突触电场电位。应用FFH神经元的自发放电作为触发信号,将此放电引起的IOMNs的电位变化进行迭加平均,结果亦获得一兴奋性单突触电场电位。这些结果表明,中·间脑结合部内侧区神经元与IOMNs之间存在兴奋性单突触联系,其作用为启动眼球的垂直运动。     

突触前α7烟碱受体对海马神经元兴奋性突触传递的调控

采用盲法膜片钳技术观察突触前烟碱受体(nicotinic acetylcholinel receptors,nAChRs)对海马脑片CAl区锥体神经元兴奋性突触传递的调控作用。结果显示,nAChRs激动剂碘化二甲基苯基哌嗪(dimethylphenyl—piperazinium iodide,DMPP)不能在CAl区锥体神经元上诱发出烟碱电流。DMPP对CAl区锥体神经元自发兴奋性突触后电流(spontaneous excitatory postsynaptic current,sEPSC)具有明显的增频和增幅作用,并呈现明显的浓度依赖关系。DMPP对微小兴奋性突触后电流(miniature excitatory postsynaptic current,mEPSC)具有增频作用,但不具有增幅作用。上述DMPP增强突触传递的作用不能被nAChRs拮抗剂美加明、六烃季铵和双氢-β-刺桐丁所阻断,但可被α-银环蛇毒素阻断。上述结果提示,海马脑片CAl区锥体神经元兴奋性突触前nAChRs含有对α-银环蛇毒素敏感的胡亚单位,其激活可增强海马CAl区锥体神经元突触前递质谷氨酸的释放,从而对兴奋性突触传递发挥调控作用。     

液压打击损伤后海马CA1区神经元兴奋性变化的研究

为考察脑损伤对海马CA1区锥体神经元电活动的影响并研究大黄素对神经元的超兴奋性和突触传递的作用,应用液压打击大鼠脑损伤模型和细胞外记录方法提取诱发的海马CA1区场兴奋性突触后电位(fPSP)和群峰电位(PS),进行相关的数据处理和分析。发现损伤侧比非损伤侧的fPSP斜率明显升高,PS波峰个教显著增加,而PS潜伏期明显减小;在灌流液中施加大黄素,CA1区诱发场电位明显减弱。研究结果表明：颅脑损伤可造成海马CA1区锥体神经元的迟发性过度兴奋;大黄素对神经元的兴奋性有抑制作用,可能对颅脑损伤后的中枢神经系统具有保护功能。     

单次注射人工合成大麻素降低大鼠中脑腹侧背盖区多巴胺能神经元兴奋性北大核心CSCD

大麻成瘾可能维持一生。中脑腹侧背盖区(ventral tegmental area,VTA)作为投射到意识及情绪相关皮层和边缘系统的多巴胺能神经元的主要来源,是奖赏系统的关键部位之一,与药物成瘾密切相关。目前,对于VTA多巴胺能神经元在药物成瘾过程中的作用研究,主要集中在药物成瘾过程中突触可塑性的变化。已有研究表明,大麻素慢性作用5天后,易化了低频电刺激诱导VTA多巴胺能神经元产生突触传递的长时程减弱(long-term depression,LTD)效应,而此过程中多巴胺能神经元兴奋性的变化情况还未见报道。实验中,作者采用离体脑片膜片钳技术,观察单次注射人工合成大麻素HU210对大鼠VTA区多巴胺能神经元兴奋性的影响。结果显示,HU210作用后,神经元基强度增大,平均放电频率降低,其细胞膜电生理特性也发生了改变,表明单次注射人工合成大麻素HU210,降低了VTA多巴胺能神经元的兴奋性,提示神经元内在兴奋性的可塑性改变可能在药物成瘾中发挥作用。     

AMPA受体参与的出生后大鼠海马发育早期的电生理学特点

本研究旨在探讨α-氨基-3-羟基-5-甲基-4-异恶唑丙酸(AMPA)受体参与的出生后大鼠海马发育早期的电生理学特点。选择出生后0.5月龄、1月龄、2月龄和3月龄Wistar大鼠共计48只(每组各12只)。应用全细胞膜片钳技术及MED64平面微电极阵列技术检测海马CA1区锥体神经元的被动膜特性及AMPA受体参与的自发兴奋性突触后电流(spontaneous exctitatory postsynaptic current,sEPSC)和场兴奋性突触后电位(field excitatory postsynaptic potential,fEPSP)。结果显示,海马CA1区锥体神经元在出生后0.5～3月龄期间,在被动膜特性方面表现为:膜电容与静息膜电位无显著性变化;膜输入电阻与时间常数均显著下降。在主动膜特性方面,呈现出阶段性变化:0.5～1月龄期间,s EPSC的反应表现为:振幅显著升高,频率明显增大,上升时间及下降时间显著增加;1～3月龄期间,sEPSC的反应特性与0.5～1月龄期间相反。此外,0.5～3月龄期间,海马CA1区诱发出的f EPSP范围明显扩大,而幅值显著减小;各月龄海马CA1区诱发出的fEPSP幅值均可被AMPA受体竞争性拮抗剂6-氰基-7-硝基喹喔啉-2,3-二酮(CNQX)明显降低。以上结果提示,在出生后大鼠海马发育早期过程中,AMPA受体作为调节突触传递和突触联系的主要兴奋性受体,可以促进海马的发育及功能成熟。     

吗啡对大鼠海马神经元突触传递的作用及机制探讨

目的 :从离子通道角度研究吗啡对中枢神经系统兴奋性及抑制性突触传递的作用并探讨其机制。方法 :　原代培养新生Wistar大鼠的海马神经元。采用膜片钳技术研究吗啡对其兴奋性及抑制性突触后电流及谷氨酸诱发电流的影响。结果 :①吗啡可明显增强海马神经元兴奋性突触传递 ,加吗啡后自发兴奋性突触后电流 (sEPSC)的发放频率增加了 ( 2 0 7.8± 2 0 .9) %。此作用可被阿片受体阻断剂纳洛酮阻断 (P <0 .0 1) ;②吗啡对微小兴奋性突触后电流 (mEPSC)的发放频率及谷氨酸诱发电流的幅度没有明显影响 (P >0 .0 5 ) ;③吗啡可明显抑制神经元自发抑制性突触后电流 (sIPSC) ,纳洛酮可拮抗吗啡作用 (n =13 ,P <0 .0 1)。结论 :实验结果提示吗啡对海马神经元的兴奋作用不是由于吗啡直接作用于兴奋性氨基酸—谷氨酸突触传递过程 ,而是可能由于抑制了抑制性中间神经元 ,间接产生的兴奋作用。     

He-Ne激光对大鼠离体颈上神经节后神经元膜电导的影响

应用细胞内生物电记录技术 ,观测不同功率、不同照射时间的 He- Ne激光 (脉冲频率 1Hz)对大鼠离体颈上神经节后神经元快兴奋性突触后电位 (f- EPSP)期间膜电导的影响。功率密度为 2 m W/ cm2 的 He- Ne激光在照射初期 (1min～ 2 min)引起快兴奋性突触后电位 (f- EPSP)幅值增大 ,同时膜电导增大 ;而在激光照射后期 (后 3m in～8m in)引起节后神经元膜电导减少。功率密度为 5 m W/ cm2 的 He- Ne激光照射期膜电导无明显变化 .结果表明 :功率密度为 2 m W/ cm2 的 He- Ne激光照射初期引起膜电导 (Gl=34.6± 5 .4 n S)较照射前 (Gf=2 6 .8± 6 .2 n S)有明显增大 (P<0 .0 5 ) ,照射后期膜电导减少。提示 :He- Ne激光照射可能是通过两时相效应改变节后神经元膜电导来影响交感神经节内兴奋传递过程。这可能是低功率激光对神经细胞的一种作用机制。     

脊髓背角胶状质神经元形态与电生理学特性的研究进展

脊髓背角胶状质神经元在痛信息传递过程中具有重要作用。其形态学分类及电生理学特性复杂,形态学大体上可分为岛神经元、中央神经元、放射状神经元、垂直神经元以及不能分类神经元;电生理学主要包括被动膜特性(静息电位、膜电容和膜电阻)、主动膜特性(动作电位,包括其放电模式、阈值、基电流、半宽度、振幅等)以及兴奋性或抑制性突触后电流等。本文对国内外脊髓背角胶状质神经元形态学与电生理学的研究进展予以综述。     

灭多威对美洲大蠊腹六神经节突触传递的阻断作用

用电生理学方法研究了灭多威对美洲大蠊Periplanetaamerwana腹六神经节(A6节)突触传递的影响。用灭多威溶液浸泡A6节,电刺激尾须神经粗支,用甘露醇间隙法记录兴奋性突触后电位(EPSP)和突触后动作电位。给予弱刺激只记录到EPSP时,灭多威作用初期EPSP幅度增加、时程延长,能诱发突触后动作电位,随后EPSP逐渐减小至消失,冲洗可恢复,突触前反应保持不变。增加电刺激强度记录到突触后动作电位时,灭多威可阻断A6节的突触传递,阻断时间是浓度依赖性的,阻断是可逆的,但冲洗30 min仍保留一定的后作用。对美洲大蠊雄性成虫腹腔注射灭多威测定致死中量(LD₅₀)为(3.56±0.01) μg/g体重。根据灭多威的作用机理对其阻断A6节突触传递的特点以及对虫体的毒杀机制进行了讨论。     

长时程增强效应初始阶段有突触前蛋白簇数目的快速增加

突触传递的长时程增强效应 (ＬＴＰ)和长时程抑制效应 (ＬＴＤ)反映神经元间突触传递效能的变化 ,目前认为这是学习和记忆的基础 ,而谷氨酸受体在ＬＴＰ和ＬＴＤ的诱导中起关键作用。海马是与学习和记忆功能密切相关的脑区 ,Ａｎｔｏｎｏｖａ等近来研究发现 ,体外培养的海马神经元在ＬＴＰ初始阶段有突触后谷氨酸受体 (ＧｌｕＲ1)簇数目的增加 ,而且在突触前神经元有突触前蛋白簇突触素数目以及突触素与谷氨酸受体共存位点数目的快速、持久的增加。进一步实验证明ＬＴＰ初始阶段并没有新蛋白的合成 ,突触前和突触后神经元蛋白质数目的快速增…     

Pressor effect of NG-nitro-L-arginine in pentobarbital-anesthetized rats

The pressor effect of NG-nitro-L-arginine (L-NNA), a potent inhibitor of nitric oxide (NO) synthesis, was studied in pentobarbital anesthetized rats. Iv injections of L-NNA from 0.25 to 8 mg/kg caused bradycardia and a dose-dependent increase in mean arterial pressure (MAP) with a maximal response of 43 +/- 5 mmHg and ED50 value of 1.3 +/- 0.2 mg/kg. The time course of the response to the injection of a single dose of L-NNA was also determined. Peak response was reached 60 min after the injection of a single dose (4 mg/kg, iv) and the effect lasted greater than 5 h. The rising phase of the pressor response was accompanied by slight bradycardia while the recovery phase was associated with significant tachycardia. Iv injections of L-arginine (12.5-200 mg/kg) caused transient dose-dependent reductions in MAP. The pressor effect of L-NNA (4 mg/kg, iv bolus) was dose-dependently attenuated by L-arginine. The results show that L-NNA is an efficacious and long-acting pressor agent and are consistent with the hypothesis that endogenous NO plays an important role in the regulation of blood pressure.     

一氧化氮的释放对海马脑片CA1区痫样放电的影响

用自制的一氧化氮（ＮＯ）敏感电极－Ｎａｆｉｏｎ－壳聚糖合镍修饰铂电极（Ｎａｆｉｏｎ－ＣＴＳ（Ｎｉ）－Ｐｔ）连续测定了青霉素致痫海马脑片ＣＡ１区锥体层神经元ＮＯ的释放,并同时观察了ＮＯ合酶抑制剂７－ｎｉｔｒｏ－ｉｎｄａｚｏｌｅ（７－ＮＩ）及Ｎ＾ω－ｎｉｔｒｏ－Ｌ－ａｒｇｉｎｉｎｅ（Ｌ－ＮＮＡ）对诱发痫波及ＮＯ释放量的影响。研究观察到：（１）在青霉素致痫脑片模型上,诱发的痫波随青霉素浓度的增加而增多,     

NO前体和供体对大鼠海马脑片神经元活动的影响

应用细胞记录单位放电技术,在大鼠海马脑片上观察了左旋精氨酸,Ｎ－硝在左旋精氨酸,ＳＩＮ－１,及亚甲基蓝对ＣＡ１区神经元自发放电的影响,旨在了解左旋精氨酸;ＮＯ通路在海马放电中的作用及其可能的机制。实验结果如下：１．用Ｌ－ａｒｇ（１ｍｍｏｌ／Ｌ）灌流海马脑片２ｍｉｎ,在５４个放电单位中有４２个单位放电频率降低,１２个单位无明显反应。     

NO介质在大鼠红藻氨酸诱导癫痫发作中的作用

目的：进一步探讨脑内一氧化氮(NO)介质(NO或NO衍生物)在复杂部分性及全身强直阵挛性癫痫发作中的作用。方法：采用红藻氨酸(KA)诱导大鼠癫痫发作,以NO合酶抑制剂L-硝基精氨酸(L-NNA)或NO前体L-精氨酸(L-Arg)予以预处理,观察其癫痫发作行为及海马结构内NO含量(NO2^-/NO3^-)的变化。结果：给予大鼠惊厥剂量KA(10mg/kg),15min时出现湿狗样抖动(WDS),1～3h出现全身痉挛;经L-NNA(50mg/kg)或L-Arg(40mg/kg)预处理的大鼠,注射相同剂量的KA后,其癫痫行为发生明显变化,L-NNA预处理的大鼠癫痫发作行为明显加重,表现为全身痉挛的潜伏期缩短、时间延长、死亡率提高;L-Arg预处理的大鼠癫痫发作行为减弱,WDS和全身痉挛的潜伏期均延长,发作程度减轻、时间缩短,观察时间内无一例死亡。KA给药后30min海马结构内的NO2^-/NO3^-含量迅速增多,7d时仍持续增高;与NS预处理组相比,经L-Arg预处理的动物,KA给药后3h及3d,其NO2^-/NO3^-浓度升高明显。结论：兴奋诱导性癫痫发作过程中内源性NO介质的变化可能具有重要的抗发作作用。     

一氧化氮抑制海马神经元兴奋的机制研究

研究青霉素诱发培养的海马CA1区神经元细胞产生的一氧化氮（NO）在兴奋过程中的抑制机制。用激光扫描共聚焦显微镜观察发现100IU／ml的青霉素可诱发一种晚而慢的NO合成模式。NO合成酶抑制剂L－NNA（0－10μmol/L）可剂量依赖地抑制NO的合成,并促进谷氨酸水的升高。同时发现L－NAA（1、10μmol/L）可显著促进进蛋氨酸脑啡肽（M－ENK）的升高）,而对强啡肽－B（DYN－B）的水平没有影响。100μmol/L的β－FNA（一种M－ENK受体抑制剂）可抑制L－NNA诱导的谷氨酸水平的升高,而100μmol/L的nor-BIN(一种DYNU受体抑制剂）对此没有影响。以上结果提示：1000IU／ml的青霉素诱导合成的NHO可通过抑制M－ENK水平来抑制神经元的兴奋。     

Nitric oxide inhibits nociceptive transmission by differentially regulating glutamate and glycine release to spinal dorsal horn neurons

Nitric oxide (NO) is involved in many physiological functions, but its role in pain signaling remains uncertain. Surprisingly, little is known about how endogenous NO affects excitatory and inhibitory synaptic transmission at the spinal level. Here we determined how NO affects excitatory and inhibitory synaptic inputs to dorsal horn neurons using whole-cell recordings in rat spinal cord slices. The NO precursor L-arginine or the NO donor SNAP significantly increased the frequency of glycinergic spontaneous and miniature inhibitory postsynaptic currents (IPSCs) of lamina II neurons. However, neither L-arginine nor SNAP had any effect on GABAergic IPSCs. L-arginine and SNAP significantly reduced the amplitude of monosynaptic excitatory postsynaptic currents (EPSCs) evoked from the dorsal root with an increase in paired-pulse ratio. Inhibition of the soluble guanylyl cyclase abolished the effect of L-arginine on glycinergic IPSCs but not on evoked monosynaptic EPSCs. Also, inhibition of protein kinase G blocked the increase in glycinergic sIPSCs by the cGMP analog 8-bromo-cGMP. The inhibitory effects of L-arginine on evoked EPSCs and high voltage-activated Ca(2+) channels expressed in HEK293 cells and dorsal root ganglion neurons were abolished by blocking the S-nitrosylation reaction with N-ethylmaleimide. Intrathecal injection of L-arginine and SNAP significantly increased mechanical nociceptive thresholds. Our findings suggest that spinal endogenous NO enhances inhibitory glycinergic input to dorsal horn neurons through sGC-cGMP-protein kinase G. Furthermore, NO reduces glutamate release from primary afferent terminals through S-nitrosylation of voltage-activated Ca(2+) channels. Both of these actions probably contribute to inhibition of nociceptive transmission by NO at the spinal level.     

一氧化氮对谷氨酸诱发的大鼠海马脑片CA1区神经元活动的抑制

用细胞外记录单位放电技术,在大鼠海马脑片上观察了Ｌ－精氨酸（Ｌ－ａｒｇ）、Ｎ－硝基Ｌ－精氨酸（Ｌ－ＮＮＡ）及ＳＩＮ－１对谷氨酸（ｇｌｕｔａｍａｔｅ,Ｇｌｕ）诱导的ＣＡ１区神经元放电的影响。旨在了解Ｌ－精氨酸：ＮＯ通路在谷氨酸诱发的海马放电中的作用及其可能的机制。结果如下：（１）用ＧｌＵ（０．５ｍｍｏｌ／Ｌ）灌流海马脑片１ｍｉｎ,１２个放电单位放电频率明显增加,表现为癫痫样放电;（２）海马脑片２ｍｉ     

Involvement of nitric oxide in cardioprotective effect of endothelin receptor antagonist during ischemia-reperfusion

The interaction between the cardioprotective effect of endothelin (ET) receptor blockade and nitric oxide (NO) during ischemia-reperfusion injury was investigated. Anesthetized pigs were subjected to 45 (protocol 1) or 30 min (protocol 2) coronary artery ligation and 4 h reperfusion. In protocol 1, five groups were given vehicle, the ET(A) receptor antagonist LU-135252 (LU), the NO synthase (NOS) inhibitor N(G)-nitro-L-arginine (L-NNA), L-NNA in combination with LU, or L-NNA in combination with the NO precursor L-arginine (L-Arg) and LU intravenously before ischemia. In protocol 2, two groups were given vehicle or L-NNA. In protocol 1, the infarct size (IS) was 79 +/- 5% of the area at risk in the vehicle group and 93 +/- 2% in the L-NNA group. LU reduced the IS to 43 +/- 7% (P < 0.001). The cardioprotective effect of LU was abolished in the presence of L-NNA (IS 76 +/- 6%), whereas addition of L-Arg restored its cardioprotective effect (IS 56 +/- 2%; P < 0.05 vs. vehicle and L-NNA + LU groups). In protocol 2, the IS was 49 +/- 6% in the vehicle group and 32 +/- 4% in the L-NNA group (P = not significant). Myocardial ET-like immunoreactivity (ET-LI) increased in the vehicle group of protocol 1. ET-LI in the ischemic-reperfused myocardium was lower in the groups given LU (P < 0.01) and L-NNA + L-Arg + LU (P < 0.05) but not in the group given L-NNA + LU compared with the vehicle group. These results suggest that the cardioprotective effect of the ET(A) receptor antagonist is mediated via a mechanism related to NO.     

NO supports right ventricular flow dominance and whole body O(2) utilization in midgestation fetal lambs

It is unknown if nitric oxide (NO) modulates the relative levels of left (LV) and right (RV) ventricular output, fetal O2 consumption, or blood flow distribution between the body and placenta at midgestation. To address these questions, six fetal lambs were instrumented at 89-96 days gestation (term 147 days), and blood flows were measured with radioactive microspheres 3-4 days later at baseline and after inhibition of NO synthesis with 10 mg/kg (L-NNA10) and 25 mg/kg (L-NNA25) N(omega)-nitro-L-arginine. LV output fell by 74 +/- 15 ml. min(-1). kg(-1) at L-NNA10 (P < 0.005), whereas RV output decreased by 90 +/- 18 ml. min(-1). kg(-1) at L-NNA10 (P < 0.02) and by a further 80 +/- 22 ml. min(-1). kg(-1) at L-NNA25 (P < 0.05). As a result, RV output exceeded LV output at baseline (P = 0.03) and L-NNA10 (P < 0.02) but not at L-NNA25. Fetal body blood flow fell by 95 +/- 25 ml. min(-1). kg(-1) at L-NNA10 (P < 0.01), but because placental blood flow decreased by 70 +/- 22 ml. min(-1). kg(-1) at L-NNA10 (P < 0.01) and a further 71 +/- 21 ml. min(-1). kg(-1) at L-NNA25 (P < 0.01), the fetal body-to-placental blood flow ratio was near unity at baseline and L-NNA10 but rose to 1.5 +/- 0.3 at L-NNA25 (P < 0.05). In association with these flow changes, fetal O2 consumption declined by 1.4 +/- 0.3 ml. min(-1). kg(-1) at L-NNA10 (P < 0.05) and by a further 1.5 +/- 0.6 ml. min(-1). kg(-1) at L-NNA25 (P < 0.02). These findings suggest that, in midgestation fetal lambs, NO supports an RV flow dominance, whole body O2 utilization, and the maintenance of a near-equal fetoplacental blood flow distribution.