大鼠离体视皮层神经元短时程时间整合特性的研究

用双脉冲白质电刺激研究了８７个大鼠视皮层神经元的短时程时间整合特性。第一个脉冲所引起的细胞反应对第二个反应有影响的细胞占被记录细胞总数的５５．２％,其中表现为突触作用增强的占４１．７％,表现为突触作用压抑的占５８．３％。整合作用的强度决定于两个脉冲之间的时间间隔,作用形式主要表现为第二个刺激所引起的反应的幅度和时程的改变。电反应可以ＥＰＳＰ或ＩＰＳＰ为主,或由ＥＰＳＰ和ＩＰＳＰ混合组成。部分细胞的反应包含快慢两个成份,时间整合作用对不同反应成份的影响程度有明显的不同。在锥体神经元中,增强型和压抑型的比例大致相等,而非锥体神经元只显示压抑型作用。位于皮层深层的神经元有时间整合作用的比率（３７．５％）比位于浅层的神经元（６０．５％）要低得多。     

金黄地鼠视皮层17、18区乙酰胆碱阳性神经元

利用乙酰胆碱( acetylcholine,Ach)自身抗体对金黄地鼠视皮层17、18区乙酰胆碱阳性神经元及其分布进行免疫学显示并进行量化分析.实验发现,Ach阳性细胞大部分为非锥体神经元,也有少量锥体神经元.Ach阳性神经元在视皮层的Ⅱ～Ⅵ层,主要分布在Ⅱ～Ⅳ层.在不同层次中其阳性神经元类型存在某些差异,Ⅱ～Ⅳ中双极细胞居多,其他层次中多极细胞占优势.17区的这类神经元数量较多且集中成垂直于皮层表面的细胞带,18区的神经元数量相对较少且多呈分散状态.     

长时程冷暴露后大鼠下丘脑脑片视前区温敏神经元的适应性变化

本文比较了生活在冷室（５±１℃，２０只）和暖室（２０±３℃，３５只）达三周的雄性Ｗｉｓｔａｒ大鼠下丘脑脑片视前区神经元电活动和温度敏感性，共记录到１２７个来自暖室组及８６个来自冷室组自发放电神经元。结果表明：（１）冷适应后冷敏神经元的比例明显提高，温度敏感性不变而放电活动的临界温度和下限温度明显下移；（２）热敏神经元的温度敏感性和临界温度降低，但在３７℃时的自发放电活动频率显著增加；（３）非温敏神经元的电活动也增加，其下限温度下移极显著，显示了大鼠视前区神经元在冷适应中的可塑性及其与冷适应中体温调节的机制相关。     

大鼠下丘脑离体脑薄片视上核神经元的全细胞记录

在大鼠下丘脑薄片标本上对52例视上核神经元进行了全细胞膜片箝记录。膜被动及主动电生理参数测量如下：静息电位,59±8mV;输入阻抗,535±129MΩ;时间常数,32±9ms;动作电位幅度,99±11mV;超射值,37±13mV（n＝39）。大多数神经元在接受去极化刺激时出现明显的慢后超极化电位或电流。我们发现,在电压箱状态下几乎所有的视上核神经元均接受兴奋性和／或抑制性突触传λ（n=13）。药理学实验表明,兴奋性突触后电流是由non－NMDA亚型谷氨酸受体介导,而抑制性突触后电流由GABAA受体介导。     

经脂多糖(LPS)处理免疫应答大鼠离体脑片视上核神经元对细胞因子敏感性的变化

实验采用离体脑片全细胞膜片箝记录方法 ,观察了细胞因子白介素 1β(IL 1β)和IL 2对大鼠离体脑片视上核神经元膜电位及自发放电的影响 ,以期探明免疫应答大鼠视上核神经元对细胞因子敏感性的变化。结果显示 ,用 10 0U/mlIL 1β灌流脑片 ,正常对照的 (n =15 )和脂多糖 (lipopolysaccharideLPS)腹腔注射 9d的大鼠视上核神经元 (n =2 0 )超极化 ,同时伴有自发放电频率的下降 ;应用 10 0U/mlIL 2 ,大部分正常对照视上核神经元 (n =14)表现为超极化 ,自发放电减少 ,剩余部分 (n =3)变化不明显 ;在LPS免疫 9d大鼠离体脑片上的 45个视上核神经元中 ,10 0U/ml的IL 2使其中 19个表现为去极化并伴有自发放电频率增加 ,16个变化不明显 ,其余 10个表现为超极化伴放电频率下降。以上结果表明 ,在免疫应答中 ,视上核神经元对细胞因子IL 2的敏感性 ,在一定的程度上发生了改变 ,细胞因子IL 2可能参与了视上核神经元的功能调节 ,进而在免疫应答过程中发挥了调节作用。     

金黄地鼠视皮层中乙酰胆碱(Ach)阳性神经元及纤维

本文通过色疫组织化学方法-PAP法,使用乙酰胆碱(Ach)抗体对金黄地鼠视皮层中的Ach进行定位Ach阳性神经元分布于视皮层的第Ⅱ—Ⅵ层,主要集中在Ⅱ、Ⅲ层.其细胞形态除大部分为非锥体神经元外,还发现有极少数锥体型神经元.这些神经元的数量和树突形态在视皮层17区和18区存在某些区域性差异.17区细胞比较密集,18区比较稀疏.17区第IA层细胞排列整齐,顶树突特别粗大,18区这种现象不太明显.皮层白质中也有少量的Ach阳性神经元.视皮层Ach阳性神经元的相对含量约为10%.视皮层中遍布外源性和内源性Ach阳性神经纤维,它们主要分布在第Ⅳ层.在视皮层微血管周围有大量Ach阳性神经元,说明对血管有舒张作用的Ach可能来源于血管内壁.     

成年大鼠体感皮层局限损伤引起的代表区重组

本文目的是探讨在成年大鼠初级体感皮层（ＳＩ）内进行局限损毁能否引起损毁区周围的代表区重组。在氯胺酮麻醉下用微电极技术测定隐神经代表区（ＳＡＲ）和坐骨神经代表区（ＳＣＲ）,然后用铂电极对ＳＡＲ进行选择性电解损毁。三至四周后进行重复测定。结果表明,在１４例所观察的大鼠中,９例在原损毁区以外发现新生的ＳＡＲ,其面积为０．２０±０．０８ｍｍ２。这表明成年大鼠ＳＩ神经元在中枢损伤后具有一定的重组能力。     

重复使用氯胺酮对成年猫视皮层神经元凋亡和BDNF表达的影响

目的研究重复使用氯胺酮麻醉剂对成年猫视皮层神经元存活和脑源性神经营养因子(BDNF)表达的影响。方法用盐酸氯胺酮对成年猫实施重复麻醉2m,每3d麻醉1次。用尼氏染色显示视皮层神经元,TUNEL-原位杂交试剂盒检测凋亡细胞,免疫组织化学ABC法标记BDNF免疫阳性神经元。光镜下观察、拍照,并用Image-Pro Express 6.0分析软件进行细胞密度统计和免疫反应光密度值测量。结果与正常对照组猫相比,实验组猫视皮层神经元数量没有显著差异(P0.05),但TUNEL阳性反应的平均光密度(IOD)值显著升高(P0.01),同时BDNF免疫阳性细胞显著增多,且BDNF免疫反应的IOD值显著增大(P0.01)。结论重复使用氯胺酮麻醉会启动成年猫视皮层神经元的程序性凋亡进程,同时会增加神经营养因子的分泌,这可能对凋亡中的神经元起保护作用。     

幼年大鼠视皮层神经元对闪光刺激的反应特性

哺乳动物视觉系统的发育延续到出生后,大鼠出生后 3~5 周是视觉系统发育的关键期 . 在关键期中,视皮层的兴奋性和抑制性突触连接逐渐成熟,形成有效的皮层内回路 . 为了观察发育关键期大鼠视皮层神经元的反应特性与成年大鼠的异同,使用胞外单细胞记录的方法对比研究了幼年和成年大鼠对闪光刺激的视觉反应特性 . 结果显示：与成年大鼠相比较,幼年大鼠视皮层神经元对持续闪光刺激显示出更强的适应性,对光刺激的诱发放电频率更低,而在没有光刺激时的自发放电频率更高,从而导致信噪比更低 . 这一结果表明,幼年大鼠视皮层对连续刺激的反应能力下降,对信号的分辨能力也更弱,其原因可能是兴奋性突触和抑制性突触发育的不同步所致 .     

坐骨神经阻滞引起成年大鼠初级体感皮层代表区的快速改变

为了探讨成年大鼠坐骨神经（ＳＣＩ）去传入后初级体感皮层是否发生快速重组,在氯胺酮麻醉下,利用微电极测定后爪代表区,然后用普鲁卡因阻滞对侧ＳＣＩ。结果表明,阻滞后１ｈ、４ｈ和８ｈ,隐神经代表区（ＳＡＲ）比对照分别增大３２．５％（ｎ＝７）、９３．０％（ｎ＝１７）和１００％（ｎ＝４）。此外,在原ＳＡＲ和新生ＳＡＲ记录的平均多单位诱发反应的峰潜伏期,后者比前者延长４．３ｍｓ。作者推测在快速出现的皮层重组机制中,皮层－皮层多突触通路的去抑制可能起重要作用     

2 Hz与100 Hz刺激在诱导大鼠视皮层长持续长时程增强中的不同作用

在哺乳动物的视皮层,多种不同参数的刺激可诱导出长时程增强(long-term potentiation,LTP)现象。但关于刺激参数与持续时间长于3h的长持续LTP(long lasting LTP,L-LTP)之间关系的研究较少。本研究用3周龄的大鼠视皮层脑片标本,在Ⅳ层刺激而在Ⅱ／Ⅲ层记录场电位,待场电位稳定后施加强直刺激诱导LTP,探讨2Hz与100Hz的强直刺激在诱发持续时间长于3h的L-LTP中的作用。结果表明,多于300个脉冲不同频率的刺激可稳定地诱导出L-LTP;2Hz与100Hz的刺激诱发的L-LTP有明显不同的表达形式,100Hz刺激可诱导出较大的L-LTP;频率相同而脉冲数不同的强直刺激诱发的L-LTP有相同的表达形式。以上结果提示,不同频率的强直刺激诱发的L-LTP机制可能不同;相同频率的刺激(脉冲数不同)诱发的L-LTP可能有相同的机制。     

Glutamate levels and transport in cat (Felis catus) area 17 during cortical reorganization following binocular retinal lesions

Glutamate is known to play a crucial role in the topographic reorganization of visual cortex after the induction of binocular central retinal lesions. In this study we investigated the possible involvement of the glial high-affinity Na+/K+-dependent glutamate transporters in cortical plasticity using western blotting and intracortical microdialysis. Basal extracellular glutamate levels and the re-uptake activity for glutamate have been determined by comparing the extracellular glutamate concentration before and during the blockage of glutamate removal from the synaptic cleft with the potent transporter inhibitor l-trans-pyrrolidine-3,4-dicarboxylic acid. In cats with central retinal lesions we observed increased basal extracellular glutamate concentrations together with a decreased re-uptake activity in non-deprived, peripheral area 17, compared with the sensory-deprived, central cortex of the same animal as well as the topographically matching regions of area 17 in normal subjects. Western blotting experiments revealed a parallel decrease in the expression level of the glial glutamate transporter proteins GLT-1 and GLAST in non-deprived cortex compared with sensory-deprived cortex of lesion cats and the corresponding regions of area 17 of normal subjects. This study shows that partial sensory deprivation of the visual cortex affects the removal of glutamate from the synaptic cleft and implicates a role for glial-neuronal interactions in adult brain plasticity.     

Comparative study on direction selectivity and functional organization of the primary visual cortical cells in monkeys and cats

Although the directionally selective cells in many visual cortical areas are organized in columnar manner, the functional organization of direction selectivity of area Vl in the monkey still remains unclear. We quantitatively studied the proportion of directionally selective cells, direction selectivity and the functional organization of the striate cortical cells in the monkey and compared those with the cat. The results show that the direction selectivity and directional organization of striate cortical cells in the monkey are significantly weaker than those in the cat, suggesting that the species difference between the two kinds of animal is related to their different anatomic pathways.     

乌拉坦对青、老年猫视皮层神经元反应特性的影响(英文)

以前的电生理研究结果显示, 老年哺乳动物视皮层细胞的自发反应及对视觉刺激的诱发反应比青年动物的显著增加, 而对光栅刺激的方位和运动方向选择性却显著下降。然而, 这种视皮层细胞功能的老年性改变是否因青、老年猫细胞对不同麻醉水平的敏感性差异引起尚不清楚。为探讨该问题, 以常用的麻醉药——乌拉坦(Urethane)为实验对象, 通过改变其麻醉剂量分别记录青、老年猫初级视皮层细胞对不同方位和运动方向光栅刺激的调谐反应。研究结果显示, 在基础麻醉量的基础上, 累积增加 50 mg 和 100 mg 乌拉坦对青、老年猫视皮层细胞的自发反应和诱发反应以及对光栅刺激方位和运动方向的选择性不产生显著影响, 累积增加 150 mg 乌拉坦会导致青、老年猫视皮层细胞对视觉刺激的反应性下降, 但下降的幅度相似。以上研究结果表明, 不同剂量的乌拉坦对青、老年动物视皮层细胞的反应性具有相似的影响。     

Comparative study on direction selectivity and functional organization of the primary visual cortical cells in monkeys and cats

Although the directionally selective cells in many visual cortical areas are organized in columnar manner, the functional organization of direction selectivity of area VI in the monkey still remains unclear. We quantitatively studied the proportion of directionally selective cells, direction selectivity and the functional organization of the striate cortical cells in the monkey and compared those with the cat. The results show that the direction selectivity and directional organization of striate cortical cells in the monkey are significantly weaker than those in the cat, suggesting that the species difference between the two kinds of animal is related to their different anatomic pathways.     

神经节苷脂GM1对体外缺糖缺氧/再灌注大鼠海马脑片保护作用的研究

目的 :探讨神经节苷脂GM 1对体外缺糖 /缺氧再灌注 (OGD/Rep)大鼠海马脑片的保护作用。 方法 :采用测定脑片OGD/Rep后光通透度改变和 2 ,3 ,5 三苯基氯化四氮唑 (TTC)染色。结果 :①在 0 (对照 )、0 .1、1.0、10 μmol/LGM1四个处理组中 ,1μmol/LGM1组脑片光通透度峰值明显低于对照组和 0 .1μmol/LGM1组 (P <0 .0 1,ANO VA) ,10 μmol/LGM 1组脑片的峰值明显低于其他组 (P <0 .0 1)。脑片OGD后光通透度到达峰值的时间在四组间有显著性差异 (P <0 .0 5 ,Kruskal Wallistest) ,1μmol/LGM1组较对照组有显著差异 (P <0 .0 1,Mann WhitneyUtest)。②GM1与OGD/RP后大鼠海马脑片TTC染色呈现一定的剂量反应关系。在 0 (对照 )、0 .0 1、0 .1、1.0、10μmol/LGM1五组中 ,1μmol/LGM 1组脑片TTC染色最深 (P <0 .0 5vs对照、0 .0 1和 0 .1μmol/L组 ,ANOVA) ,10 μmol/LGM 1组次之 (P <0 .0 5vs对照和 0 .0 1μmol/L组 ,ANOVA)。 结论 :GM 1可以有效的保护体外大鼠海马脑片缺糖 /缺氧再灌注损伤。     

Global perception depends on coherent work of bilateral visual cortices: Transcranial magnetic stimulation (TMS) studies

Previous research suggests that the right and left hemispheres dominate global and local perception of hierarchical patterns, respectively. The current work examined whether global perception of hierarchi-cal stimuli requires coherent work of bilateral visual cortices using transcranial magnetic stimulation (TMS). Subjects discriminated global or local properties of compound letters in Experiment 1. Reaction times were recorded when single-pulse real TMS or sham TMS was delivered over the left or right visual cortex. While a global precedence effect (i.e., faster responses to global than local targets and stronger global-to-local interference than the reverse) was observed, TMS decreased global-to-local interference whereas increased local-to-global interference. Experiment 2 ruled out the possibility that the effects observed in Experiment 1 resulted from perceptual learning. Experiment 3 used compound shapes and observed TMS effect similar to that in Experiment 1. Moreover, TMS also slowed global RTs whereas speeded up local RTs in Experiment 3. Finally, the TMS effects observed in Experiments 1 and 3 did not differ between the conditions when TMS was applied over the left and right hemispheres. The results support a coherence hypothesis that global perception of compound stimuli depends upon the co-herent work of bilateral visual cortices.     

Global perception depends on coherent work of bilateral visual cortices: Transcranial magnetic stimulation (TMS) studies

Previous research suggests that the right and left hemispheres dominate global and local perception of hierarchical patterns, respectively. The current work examined whether global perception of hierarchical stimuli requires coherent work of bilateral visual cortices using transcranial magnetic stimulation (TMS). Subjects discriminated global or local properties of compound letters in Experiment 1. Reaction times were recorded when single-pulse real TMS or sham TMS was delivered over the left or right visual cortex. While a global precedence effect (i.e., faster responses to global than local targets and stronger global-to-local interference than the reverse) was observed, TMS decreased global-to-local interference whereas increased local-to-global interference. Experiment 2 ruled out the possibility that the effects observed in Experiment 1 resulted from perceptual learning. Experiment 3 used compound shapes and observed TMS effect similar to that in Experiment 1. Moreover, TMS also slowed global RTs whereas speeded up local RTs in Experiment 3. Finally, the TMS effects observed in Experiments 1 and 3 did not differ between the conditions when TMS was applied over the left and right hemispheres. The results support a coherence hypothesis that global perception of compound stimuli depends upon the coherent work of bilateral visual cortices.     

视皮层LTP维持阶段的突触形态计量学研究

本实验使用１８～２０ｄ的幼年大鼠视皮层脑片标本,在ＬＴＰ出现后３ｈ取局部微脑片固定进行ＬＴＰ维持阶段超微结构的研究。分别与孵育相同时间而未予任何刺激的脑片和仅给予测试刺激的脑片作比较。运用图像分析仪分别对三组电镜结果进行以下参数的测量：（１）突触间隙的宽度;（２）突触后致密物（ＰＳＤ）的厚度;（３）活性区的长度;和（４）突触界面曲率。用双盲法对突触数目进行计量,并用立体计量学方法对各种突触类型进行定量,所得数据用方差分析进行统计学处理。结果显示：（１）ＬＴＰ形成后１５ｈ左右,其反应达到峰值,然后维持在最高水平一直到３ｈ仍无下降趋势;（２）突触间隙的宽度较两个对照组明显增宽;（３）ＰＳＤ的厚度也明显增厚;（４）活性区的面密度及突触界面曲率明显增加;（５）总突触数目和棘突触数目的数密度较空白对照明显增高;（６）穿孔性突触的数密度与对照组相比明显增加。结果提示：活性区面密度的增加及突触界面曲率的增大可能是ＬＴＰ维持的形态学基础。穿孔性突触的形成与ＬＴＰ的维持密切相关。     

Effects of desipramine treatment on norepinephrine transporter gene expression in the cultured SK-N-BE(2)M17 cells and rat brain tissue

The antidepressant desipramine (DMI) is a selective inhibitor of norepinephrine (NE) transport that down-regulates the norepinephrine transporter (NET) protein in a concentration- and time-dependent manner in vitro. In this study, possible regulatory effects of DMI on NET mRNA and protein levels were investigated with the NET-expressing SK-N-BE(2)M17 cell line and rat brain tissue. Northern blot analysis showed that incubation of the cultured cells with DMI (5-500 nm) for 3 days reduced levels of NET mRNA in both its 5.8-kb (by up to 58%) and 3.6-kb forms (to 68%), whereas incubation for 14 days increased both levels (to 40% and 100%) in a concentration-dependent manner. In contrast, NET protein levels decreased after 3-14 days of exposure of the cells to DMI, as determined by western blotting. The in vitro findings were supported by in vivo treatment of rats with DMI. Thus, in situ hybridization demonstrated initially decreased, and later increased, NET mRNA levels in locus coeruleus (LC) tissue of rats treated with DMI; whereas NET protein levels in the LC were reduced after 14 days, but unchanged after three daily DMI treatments. Thus, DMI had similar effects on NET expression in vitro and in vivo, with opposite changes in NET mRNA and protein levels, suggesting that the regulatory mechanisms involved are complex and non-congruent.