皮质发育障碍大鼠模型学习记忆行为和海马长时程增强的研究

目的：研究皮质发育障碍（DCD）大鼠模型空间学习记忆及离体海马长时程增强（LTP）变化,探讨DCD大鼠模型认知功能损伤的机制。方法：建立DCD大鼠模型,采用Morris水迷宫实验对DCD大鼠模型和正常对照组进行空间学习、记忆的行为学检测,应用膜片钳技术研究DCD大鼠模型海马脑片CA1区LTP的改变。结果：Morris水迷宫实验中DCD大鼠与正常对照组相比逃避潜伏期延长,穿过原平台位置次数和在原平台象限探索时间百分率下降;DCD大鼠模型海马脑片CA1区LTP诱出率、幅值增加百分率与正常对照组相比均明显降低[（40％vs100％,P〈0．05;（108±5．6）％vs（132±15．4）％,P〈0．05）]。结论：DCD大鼠模型的空间学习记忆能力降低,海马突触可塑性也发生降低。     

皮质发育障碍大鼠海马神经元的体视学方法定量研究

目的　用体视学方法计数比较X射线制作的大脑皮质发育障碍（DCDs）模型大鼠海马神经元数量变化和测量海马体积变化。 方法　选择2月龄正常SD大鼠和DCDs模型鼠各5 只,取脑后石蜡包埋、连续冠状切片。根据均匀系统随机抽样原则,从含海马结构的切片中随机抽取一组切片,组织化学染色,在体视学设备下计数大鼠海马CA1、CA3和DG区的神经元数目和测量海马体积。 结果　正常大鼠单侧海马CA1、CA3和DG区的神经元的数目分别是（8.35×104±1.44×104）、（8.23×104±1.60×104）和（1.43×105±2.24×104）,DCDs模型大鼠单侧海马CA1、CA3和DG区的神经元的数目分别是（3.70×104±　1.96×104）、（3.57×104±1.47×104）和（6.86×104±4.85×104）;正常大鼠和DCDs模型鼠单侧海马的体积分别是(14.18±1.52)mm3和(8.49±3.41)mm3。DCDs大鼠海马结构各亚区的神经元数量和海马体积均较正常鼠明显减小（P＜0.05）。 结论　X射线制作的DCDs模型鼠海马CA1、CA3和DG的神经元数目和海马体积都较正常大鼠减少。     

大脑皮质发育障碍模型病理学与影像学研究

目的：探讨应用X射线构建的大脑皮质发育障碍（DCD）模型鼠病理学与影像学特点。方法：应用直线加速器以175cGy剂量照射孕17dSD母鼠,待仔鼠满56d时行鼠脑磁共振扫描后处死,取脑进行组织病理学研究。结果：DCD仔鼠较对照组大鼠大脑组织重量减轻,体积显著缩小,大脑皮层变薄,厚度较小,双侧侧脑室、第三脑室、第四脑室明显扩大;光镜下见大脑皮层结构紊乱,其内可见结节,海马结构紊乱,海马内结节明显。DCD仔鼠头颅MRI特点：脑体积略小,皮层厚度变薄,双侧侧脑室、第三脑室、第四脑室明显扩大,胼胝体变小伴有缺如,四叠体明显暴露,小脑体积变大。结论：DCD从模型鼠病理学与影像学特征可以反映X射线是构建大脑皮质发育障碍的有效方法,影像学是评估DCD造模是否成功的可供选择的一种手段。     

琥珀酸在海马CA1区对突触前GABA释放的影响

为了观察琥珀酸在大鼠海马CA1区对突触前GABA释放的影响,我们采用红外可视全细胞膜片钳技术记录了琥珀酸对γ-氨基丁酸(GABA)能自发性微小抑制性突触后电流(miniature inhibitory postsynaptic currents,mIPSCs)的作用。结果显示不同浓度的琥珀酸(10-6mol/L、10-5mol/L、10-4mol/L和10-3mol/L)在海马CA1区均能以浓度依赖的方式增强GABA能mIPSCs的频率,而对其电流幅度没有影响。10-4mol/L琥珀酸组GABA能mIPSCs的频率为2.25±0.99Hz,与正常对照组相比有显著性差异(n=8,P<0.01),而其电流幅度为31.63±6.16pA,与正常对照组相比没有差异(n=8,P>0.05)。以上实验结果表明琥珀酸能通过增强突触前GABA的自发性释放,对海马CA1区神经元产生超极化作用,此作用可能是琥珀酸抑制癫痫形成的主要方式之一。     

大鼠海马CA3区在学习记忆时突触可塑性的变化

目的：探讨学习记忆的形成和遗忘与突触可塑性的关系。方法：用水迷宫训练大鼠21天建立空间辨别性学习记忆模型,随后停止训练,时间分别为3天,7天及14天,用免疫组化方法和图像分析技术,检测了突触素在大鼠海马CA3区表达的变化。结果：对照组大鼠海马CA3区突触素的表达弱,免疫反应产物呈点状颗粒,沿辐射层长轴分布,多形层也有散在分布;模型组大鼠突触素染色明显比对照组的深,密集的小颗粒呈带状沿辐射层排列,在辐射层的底部可见一些大的阳性颗粒,随着停止训练时间的延长,突触素的表达逐渐减弱。结论：空间学习记忆导致海马CA3区辐射层新突触的形成,而随着空间学习记忆的遗忘,又致新形成突触的消退。     

脑缺血及再灌流早期大鼠海马CA1区NMDA受体的变化

探讨脑缺血和缺血再灌流早期海马CA1 区NMDA受体的变化规律,选用雄性SD大鼠 48只,随机分为:假手术对照组、单纯脑缺血 15min、20min和 30min组及脑缺血 15min再灌流 0min、30min和 24h组,参照Pulsinelli Brierley(4VO)法制作脑缺血模型,取脑,连续冰冻冠状切片,NR1免疫组化染色并进行图像分析及计算阳性单位PU值。结果显示: (1 )单纯脑缺血 15min、20min和 30min组PU值分别为 5. 89±0. 92、5. 18±1. 63和 4. 89±2. 69,与对照组PU值 7. 56±2. 35相比,下降 22. 09% ~35. 32% (P≤0.05); (2)再灌流 30min和 24h组PU值分别为 4. 20±1. 37和 2. 99±1. 28,与对照组PU值相比,减少 44. 44% ~60. 45%,有统计学意义(P<0.05),均明显降低; (3)再灌流 0min、30min和 24h组两两比较, 24h和 0min组的NMDA受体减少有统计学意义(P<0.05)。上述结果提示,脑缺血和缺血再灌流早期海马CA1 区NMDA受体存在下行调节,这可能是脑缺血后自身的一种保护性调节。     

大脑皮质发育不良大鼠脑皮质和海马中的NeuN和GFAP表达研究

目的：探讨大脑皮质发育不良（DCD）大鼠大脑半球、海马的免疫组化病理学特点及其所致难治性癫痫（IE）的发生机制。方法：建立X-射线照射诱导的皮质下异位结节大鼠DCD模型,采用SP免疫组织化学方法检测神经元特异核蛋白抗原（NeuN）和星形胶质细胞特异抗原（GFAP）在大鼠脑皮质下和海马中异位结节的表达,阳性细胞计数,用SPSS10．0软件统计。结果：DCD组与正常对照或母鼠组白质比较,皮质下异位结节内NeuN免疫阳性神经元和GFAP免疫阳性细胞数密度分别增加30倍和16倍,差异有统计学意义（P〈0．05）。同龄而不同部位DCD病变组间脑皮质Ⅰ～Ⅲ层异位结节、皮质下异位结节和CA1区异位结节中NeuN、GFAP免疫阳性细胞数密度或阳性平均光密度值比较,差异无统计学意义。结论：DCD鼠脑NeuN及GFAP的分布证实了皮质下异位结节的内在属性,异位结节是灰质,主要是由神经元和星形胶质细胞构成。     

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。     

海马CA1区5-HT_(1A)受体调控PTSD大鼠空间记忆的作用

目的:观察创伤后应激障碍(PTSD)大鼠海马长时程增强(LTP)的变化以及5-羟色胺1A受体(5-HT_(1A)受体)和突触后致密物蛋白95(PSD-95)的表达,探讨5-HT_(1A)受体调控PTSD大鼠空间记忆的机制。方法:健康成年SD大鼠36只,随机分为正常对照组和模型组,每组18只。模型组采用连续单一刺激构建PTSD大鼠模型。Morris水迷宫实验检测2组大鼠的学习和记忆能力,电生理实验检测强直性高频刺激对海马LTP的影响Western blot法和免疫荧光实验检测海马5-HT_(1A)受体和PSD-95蛋白的表达。结果:Morris水迷宫实验结果显示在各实验日模型组大鼠逃避平台的潜伏期较对照组显著延长(P0.05)。电生理实验结果显示在强直性高频刺激后,2组大鼠海马诱发电位的幅值明显升高,模型组诱发电位的幅值显著低于对照组(P0.01)。Westem blot实验和免疫荧光实验结果显示,与对照组比较,模型组大鼠海马CA1区5-HT_(1A)受体的表达显著增加(P0.05),但PSD-95的表达明显减少(P0.05)。结论:PTSD大鼠空间记忆能力减退,可能与海马CA1区5-HT_(1A)受体的表达增加和PSD-95的表达减少有关。     

Physiological heterogeneity of nonpyramidal cells in rat hippocampal CA1 region

Summary Functional differentiation of nonpyramidal cells was studied by intracellular recording and staining of cells located in the stratum pyramidale or along the border between the stratum radiatum and the stratum lacunosum-moleculare of slices prepared from rat hippocampal CA1 region. In the stratum pyramidale, nonpyramidal cells (fast-spiking cells, type I cells) exhibited brief-duration action potentials (mean spike-width at one-half amplitude = 0.28 ms, N = 9) and little or no frequency adaptation of spike discharge to depolarizing current pulse. These cells ramified axon collaterals mainly in the stratum pyramidale or in the apical side of the stratum oriens. The HRP-injected nonpyramidal cells located between the stratum radiatum and the stratum lanunosum-moleculare (type II cells) showed different physiological characteristics from fast-spiking cells in the stratum pyramidale. The spike width was longer than that of fast-spiking cells (mean duration measured at one-half amplitude = 0.61 ms, N = 11) and these cells exhibited adaptation of spike discharge in response to depolarizing current pulses. Following hyperpolarizing current pulses, a depolarizing potential was produced in some type II cells. Although most cells of this group sent axon collaterals into the stratum radiatum or into the stratum lacunosum-moleculare, there were also cells whose axon collaterals extended to and ramified in the stratum pyramidale. In contrast to pyramidal cells, spikes of both types of nonpyramidal cells did not broaden during repetitive firing evoked by large depolarizing current pulses. Stimulation of the stratum radiatum caused excitatory and inhibitory postsynaptic potentials in both type I and II cells. These results suggest that hippocampal nonpyramidal cells are divided into at least two groups; type I cells (fast-spiking cells) and type II cells.     

焦亚硫酸钠对大鼠海马CA1区神经元钠电流的影响

目的：探讨SO2 及其体内衍生物（亚硫酸盐和亚硫酸氢盐）对中枢神经元钠通道的影响。 方法: 采用全细胞膜片钳技术研究了焦亚硫酸钠（SMB）对大鼠海马CA1区神经元钠电流的影响及超氧化物歧化酶(SOD)、过氧化氢酶(CAT)及谷胱甘肽过氧化物酶(GPx)相应的保护作用。 结果： ① 焦亚硫酸钠可剂量依赖性地增大全细胞钠电流，剂量为2 μmol/L和20 μmol/L时，钠电流分别增大（22.36±3.28）% 和（65.05±5.75）%（n=10）。② 10　μmol/L的焦亚硫酸钠不影响钠电流的激活过程，却非常显著地影响其失活过程，使失活曲线显著右移，作用前后的半数失活电压分别为（-82.38±0.54）mV和（-69.39±0.41）mV (n=10, P<0.01), 但失活曲线的斜率因子未见改变。③ SOD(1×106 U/L)、CAT(2×106 U/L) 及GPx (1×104 U/L) 均可使SMB（10 μmol/L）增大的钠电流部分恢复。 结论： SMB增大钠电流并抑制其失活过程，从而影响神经细胞的兴奋性，这一效应可能与硫中心或氧中心自由基的损伤作用有关。     

Behavior-dependent paired-pulse responses in the hippocampal CA1 region

Summary Paired-pulses of 20–100 ms interpulse interval (IPI) were delivered to the Schaffer collaterals/commissural fibers in order to excite the apical dendrites of the hippocampal CA1 region in freely behaving rats. Significant differences were observed for the paired-pulse responses during different behavioral states. The responses recorded during awake immobility (IMM), and slow-wave sleep (SWS) were similar, but as a group, were different from those during walking (WLK) and rapid-eye-movement sleep (REM). During WLK and REM, the population spike evoked by the second pulse (P2) at IPI of 30 and 50 ms, was greatly facilitated as compared to the population spike evoked by the first pulse (P1), i.e. P2 > P1. During IMM and SWS and using moderate stimulus intensities, P2 was generally smaller than P1 (paired-pulse suppression) at IPI of 30 and 50 ms. The P2/P1 relation with behavior was not caused by the slight variations of P1 with behavior. In addition, paired-pulse facilitation of the population excitatory postsynaptic potentials (EPSP) was relatively small and not significantly dependent on behavior. Behavioral dependence of the paired-pulse responses was not generally found for IPI of 20 or 100 ms. It is concluded that paired-pulse facilitation at 30–50 ms IPI can best be explained by EPSP facilitation combined with a behaviorally dependent disinhibition.     

低氧大鼠海马脑片CA1区长时程增强的变化及ACTH的作用

目的: 研究ACTH对低氧海马脑片CA1区长时程增强的影响。方法: 细胞外记录海马脑片CA1区诱发的群峰电位(PS)和强直刺激诱发的长时程增强(LTP)。结果: 低氧(5% O₂+90% N₂+5% CO₂或11.2% O₂+83.8% N₂+5% CO₂)灌流海马脑片后, LTP的诱出时间显著延长、诱出率明显降低, PS迅速减少并逐渐消失。预先灌流ACTH可改善上述效应。结论: 低氧可损害海马脑片CA1区LTP的诱发过程, ACTH可使之改善。     

红藻氨酸对大鼠海马锥体细胞钙电流的影响

目的：应用膜片钳技术,观察红藻氨酸（KA）对大鼠海马锥体细胞ca2＋电流的影响,以研究癫痫的发病机制。方法：采用酶加机械分离法制备出生10～12d的大鼠海马锥体神经元标本,用全细胞膜片钳技术测定其生理学特性及观察KA对ca2＋电流的影响。结果：分离出的海马锥体细胞形态正常,有较长突起;用膜片钳技术证实,其保存了主要的离子通道活性。KA20μmol／L和100μmol／L的浓度均可使海马锥体细胞ca2＋电流峰值增大（n=8,P〈0．01）。结论：①大鼠海马锥体神经细胞具有明显的突起,细胞膜表面光洁、晕光好,适用于膜片钳实验研究;②KA使ca2＋内流增加,引起“Ca”超载”导致细胞毒性等一系列反应;③KA通过激活α-氨基羟甲基恶唑丙酸（AMPA）受体,诱发快速的兴奋性突触后电位（EPSP）,参与兴奋性突触传递。AMPA受体的激活可能是癫痫的发病机制之一。     

PTSD大鼠海马CA1区和前额叶皮层突触小泡蛋白的表达

目的:观察创伤后应激障碍(posttraumatic stress disorder,PTSD)大鼠海马CA1区和前额叶皮层(prefrontal cortex,PFC)突触小泡蛋白(synaptophysin)的表达,探讨PTSD大鼠空间记忆损伤的机制。方法:健康成年SD大鼠36只,随机分为正常对照组和模型组,每组18只。模型组采用单次延长应激(single prolonged stress,SPS)构建PTSD大鼠模型。Morris水迷宫实验检测2组大鼠的学习记忆能力,利用免疫组化、Western blot和免疫荧光实验检测海马CA1区和PFC突触小泡蛋白的表达情况。结果:经过Morris水迷宫实验,模型组大鼠从第2天开始逃避平台的潜伏期较对照组均显著延长(P 0.01),目标象限的停留时间均明显降低(P 0.01),穿越原平台位置的次数也明显减少(P 0.01)。在免疫组化、Western blot和免疫荧光实验中,模型组大鼠海马CA1区和PFC突触小泡蛋白的表达较对照组均明显减少(P 0.05或P 0.01)。结论:创伤后应激障碍大鼠空间记忆能力减退,可能与海马CA1区和PFC突触小泡蛋白的表达减少有关。     

Sustained expression of parvalbumin immunoreactivity in the hippocampal CA1 region and dentate gyrus during aging in dogs

The hippocampus contains a heterogeneous population of interneurons. Parvalbumin (PV) positive neurons constitute an abundant subpopulation of cells that express GABA. The authors observed PV immunoreactivity in the hippocampal CA1 region and dentate gyrus of variously aged dogs. In 1-year-old dogs, PV immunoreactive neurons were detected in the stratum oriens of the CA1 region, and in the polymorphic layer of the dentate gyrus. In addition, weak PV immunoreactive fibers were observed in all layers in the CA1 region and dentate gyrus. In 3-year-old dogs, PV immunoreactivity was significantly higher in the CA1 region and dentate gyrus, and this was maintained in 10-year-old dogs. This finding suggests that PV immunoreactive interneurons may show high resistance to age-dependent neurodegenerative processes.     

Changes of interhemispheric hippocampal responses during conditioning in the awake rat

Summary The responses of the hippocampus of the awake rat to stimulation of one of its afferent pathways were measured during classical conditioning. It was found that when the contralateral hippocampus is stimulated concurrently with the presentation of a conditioned stimulus preceding either food or an aversive shock, a late (30–40 msec) negative component in the averaged evoked response can be recorded. This late component was absent when the interhemispheric stimulation was applied prior to presentation of a conditioned stimulus or when the rat was satiated or pretreated with drugs which interfere with noradrenergic or serotonergic neurotransmission. It is suggested that classical conditioning changes neurotransmission in certain pathways in the brain and that the monoamines are involved in mediation of this change.