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Sample records for cultured hippocampal pyramidal

  1. Differentiation of apical and basal dendrites in pyramidal cells and granule cells in dissociated hippocampal cultures.

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    Wu, You Kure; Fujishima, Kazuto; Kengaku, Mineko

    2015-01-01

    Hippocampal pyramidal cells and dentate granule cells develop morphologically distinct dendritic arbors, yet also share some common features. Both cell types form a long apical dendrite which extends from the apex of the cell soma, while short basal dendrites are developed only in pyramidal cells. Using quantitative morphometric analyses of mouse hippocampal cultures, we evaluated the differences in dendritic arborization patterns between pyramidal and granule cells. Furthermore, we observed and described the final apical dendrite determination during dendritic polarization by time-lapse imaging. Pyramidal and granule cells in culture exhibited similar dendritic patterns with a single principal dendrite and several minor dendrites so that the cell types were not readily distinguished by appearance. While basal dendrites in granule cells are normally degraded by adulthood in vivo, cultured granule cells retained their minor dendrites. Asymmetric growth of a single principal dendrite harboring the Golgi was observed in both cell types soon after the onset of dendritic growth. Time-lapse imaging revealed that up until the second week in culture, final principal dendrite designation was not stabilized, but was frequently replaced by other minor dendrites. Before dendritic polarity was stabilized, the Golgi moved dynamically within the soma and was repeatedly repositioned at newly emerging principal dendrites. Our results suggest that polarized growth of the apical dendrite is regulated by cell intrinsic programs, while regression of basal dendrites requires cue(s) from the extracellular environment in the dentate gyrus. The apical dendrite designation is determined from among multiple growing dendrites of young developing neurons.

  2. Differentiation of apical and basal dendrites in pyramidal cells and granule cells in dissociated hippocampal cultures.

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    You Kure Wu

    Full Text Available Hippocampal pyramidal cells and dentate granule cells develop morphologically distinct dendritic arbors, yet also share some common features. Both cell types form a long apical dendrite which extends from the apex of the cell soma, while short basal dendrites are developed only in pyramidal cells. Using quantitative morphometric analyses of mouse hippocampal cultures, we evaluated the differences in dendritic arborization patterns between pyramidal and granule cells. Furthermore, we observed and described the final apical dendrite determination during dendritic polarization by time-lapse imaging. Pyramidal and granule cells in culture exhibited similar dendritic patterns with a single principal dendrite and several minor dendrites so that the cell types were not readily distinguished by appearance. While basal dendrites in granule cells are normally degraded by adulthood in vivo, cultured granule cells retained their minor dendrites. Asymmetric growth of a single principal dendrite harboring the Golgi was observed in both cell types soon after the onset of dendritic growth. Time-lapse imaging revealed that up until the second week in culture, final principal dendrite designation was not stabilized, but was frequently replaced by other minor dendrites. Before dendritic polarity was stabilized, the Golgi moved dynamically within the soma and was repeatedly repositioned at newly emerging principal dendrites. Our results suggest that polarized growth of the apical dendrite is regulated by cell intrinsic programs, while regression of basal dendrites requires cue(s from the extracellular environment in the dentate gyrus. The apical dendrite designation is determined from among multiple growing dendrites of young developing neurons.

  3. Loss of glutathione homeostasis associated with neuronal senescence facilitates TRPM2 channel activation in cultured hippocampal pyramidal neurons

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    Belrose Jillian C

    2012-04-01

    Full Text Available Abstract Background Glutathione (GSH plays an important role in neuronal oxidant defence. Depletion of cellular GSH is observed in neurodegenerative diseases and thereby contributes to the associated oxidative stress and Ca2+ dysregulation. Whether depletion of cellular GSH, associated with neuronal senescence, directly influences Ca2+ permeation pathways is not known. Transient receptor potential melastatin type 2 (TRPM2 is a Ca2+ permeable non-selective cation channel expressed in several cell types including hippocampal pyramidal neurons. Moreover, activation of TRPM2 during oxidative stress has been linked to cell death. Importantly, GSH has been reported to inhibit TRPM2 channels, suggesting they may directly contribute to Ca2+ dysregulation associated with neuronal senescence. Herein, we explore the relation between cellular GSH and TRPM2 channel activity in long-term cultures of hippocampal neurons. Results In whole-cell voltage-clamp recordings, we observe that TRPM2 current density increases in cultured pyramidal neurons over time in vitro. The observed increase in current density was prevented by treatment with NAC, a precursor to GSH synthesis. Conversely, treatment of cultures maintained for 2 weeks in vitro with L-BSO, which depletes GSH by inhibiting its synthesis, augments TRPM2 currents. Additionally, we demonstrate that GSH inhibits TRPM2 currents through a thiol-independent mechanism, and produces a 3.5-fold shift in the dose-response curve generated by ADPR, the intracellular agonist for TRPM2. Conclusion These results indicate that GSH plays a physiologically relevant role in the regulation of TRPM2 currents in hippocampal pyramidal neurons. This interaction may play an important role in aging and neurological diseases associated with depletion of GSH.

  4. The rostral migratory stream generates hippocampal CA1 pyramidal-like neurons in a novel organotypic slice co-culture model

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    Ilyas Singec

    2015-10-01

    Full Text Available The mouse subventricular zone (SVZ generates large numbers of neuroblasts, which migrate in a distinct pathway, the rostral migratory stream (RMS, and replace specific interneurons in the olfactory bulb (OB. Here, we introduce an organotypic slice culture model that directly connects the RMS to the hippocampus as a new destination. RMS neuroblasts widely populate the hippocampus and undergo cellular differentiation. We demonstrate that RMS cells give rise to various neuronal subtypes and, surprisingly, to CA1 pyramidal neurons. Pyramidal neurons are typically generated before birth and are lost in various neurological disorders. Hence, this unique slice culture model enables us to investigate their postnatal genesis under defined in vitro conditions from the RMS, an unanticipated source for hippocampal pyramidal neurons.

  5. Dendritic potassium channels in hippocampal pyramidal neurons.

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    Johnston, D; Hoffman, D A; Magee, J C; Poolos, N P; Watanabe, S; Colbert, C M; Migliore, M

    2000-05-15

    Potassium channels located in the dendrites of hippocampal CA1 pyramidal neurons control the shape and amplitude of back-propagating action potentials, the amplitude of excitatory postsynaptic potentials and dendritic excitability. Non-uniform gradients in the distribution of potassium channels in the dendrites make the dendritic electrical properties markedly different from those found in the soma. For example, the influence of a fast, calcium-dependent potassium current on action potential repolarization is progressively reduced in the first 150 micrometer of the apical dendrites, so that action potentials recorded farther than 200 micrometer from the soma have no fast after-hyperpolarization and are wider than those in the soma. The peak amplitude of back-propagating action potentials is also progressively reduced in the dendrites because of the increasing density of a transient potassium channel with distance from the soma. The activation of this channel can be reduced by the activity of a number of protein kinases as well as by prior depolarization. The depolarization from excitatory postsynaptic potentials (EPSPs) can inactivate these A-type K+ channels and thus lead to an increase in the amplitude of dendritic action potentials, provided the EPSP and the action potentials occur within the appropriate time window. This time window could be in the order of 15 ms and may play a role in long-term potentiation induced by pairing EPSPs and back-propagating action potentials.

  6. Hippocampal CA3 pyramidal cells selectively innervate aspiny interneurons.

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    Wittner, Lucia; Henze, Darrell A; Záborszky, László; Buzsáki, György

    2006-09-01

    The specific connectivity among principal cells and interneurons determines the flow of activity in neuronal networks. To elucidate the connections between hippocampal principal cells and various classes of interneurons, CA3 pyramidal cells were intracellularly labelled with biocytin in anaesthetized rats and the three-dimensional distribution of their axon collaterals was reconstructed. The sections were double-stained for substance P receptor (SPR)- or metabotropic glutamate receptor 1alpha (mGluR-1alpha)-immunoreactivity to investigate interneuron targets of the CA3 pyramidal cells. SPR-containing interneurons represent a large portion of the GABAergic population, including spiny and aspiny classes. Axon terminals of CA3 pyramidal cells contacted SPR-positive interneuron dendrites in the hilus and in all hippocampal strata in both CA3 and CA1 regions (7.16% of all boutons). The majority of axons formed single contacts (87.5%), but multiple contacts (up to six) on single target neurons were also found. CA3 pyramidal cell axon collaterals innervated several types of morphologically different aspiny SPR-positive interneurons. In contrast, spiny SPR-interneurons or mGluR-1alpha-positive interneurons in the hilus, CA3 and CA1 regions were rarely contacted by the filled pyramidal cells. These findings indicate a strong target selection of CA3 pyramidal cells favouring the activation of aspiny classes of interneurons.

  7. Pyramidal cell-interneuron interactions underlie hippocampal ripple oscillations.

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    Stark, Eran; Roux, Lisa; Eichler, Ronny; Senzai, Yuta; Royer, Sebastien; Buzsáki, György

    2014-07-16

    High-frequency ripple oscillations, observed most prominently in the hippocampal CA1 pyramidal layer, are associated with memory consolidation. The cellular and network mechanisms underlying the generation, frequency control, and spatial coherence of the rhythm are poorly understood. Using multisite optogenetic manipulations in freely behaving rodents, we found that depolarization of a small group of nearby pyramidal cells was sufficient to induce high-frequency oscillations, whereas closed-loop silencing of pyramidal cells or activation of parvalbumin- (PV) or somatostatin-immunoreactive interneurons aborted spontaneously occurring ripples. Focal pharmacological blockade of GABAA receptors abolished ripples. Localized PV interneuron activation paced ensemble spiking, and simultaneous induction of high-frequency oscillations at multiple locations resulted in a temporally coherent pattern mediated by phase-locked interneuron spiking. These results constrain competing models of ripple generation and indicate that temporally precise local interactions between excitatory and inhibitory neurons support ripple generation in the intact hippocampus.

  8. Culturing rat hippocampal neurons.

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    Audesirk, G; Audesirk, T; Ferguson, C

    2001-01-01

    Cultured neurons are widely used to investigate the mechanisms of neurotoxicity. Embryonic rat hippocampal neurons may be grown as described under a wide variety of conditions to suit differing experimental procedures, including electrophysiology, morphological analysis of neurite development, and various biochemical and molecular analyses.

  9. Dendritic development of hippocampal CA1 pyramidal cells in a neonatal hypoxia-ischemia injury model.

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    Zhao, Yan Dong; Ou, Shan; Cheng, Sai Yu; Xiao, Zhi; He, Wen Juan; Zhang, Jin Hai; Ruan, Huai Zhen

    2013-09-01

    It is believed that neonatal hypoxia-ischemia (HI) brain injury causes neuron loss and brain functional defects. However, the effect of HI brain injury on dendritic development of the remaining pyramidal cells of the hippocampus and the reaction of contralateral hippocampal neurons require further studies. The Morris water maze and Golgi-Cox staining were used to evaluate the learning and memory and dendritic morphology of pyramidal cells. The results of Golgi-Cox staining showed CA1 pyramidal neurons of HI injury models with fewer bifurcations and shorter dendrite length than the naive control group. The density of dendritic spines of hippocampal CA1 pyramidal neurons was significantly lower in the HI brain injury group than in controls. With respect to hippocampal function, the HI brain injury group presented cognitive deficits in the reference memory task and probe trail. In the HI group, the pyramidal cells of left hippocampus that did not experienced ischemia but did experience hypoxia had more complex dendrites and higher density of spine than the HI injury side and control. The functional implementation of injured hippocampus might depend mainly on the hypertrophy of contralateral hippocampus after HI brain injury. Corticosterone can partially prevent the hippocampal pyramidal cells from HI injury and reduce the difference of the bilateral hippocampus pyramidal cells, but there was no improvement in learning and memory.

  10. Housing under the pyramid reduces susceptibility of hippocampal CA3 pyramidal neurons to prenatal stress in the developing rat offspring.

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    Murthy, Krishna Dilip; George, Mitchel Constance; Ramasamy, Perumal; Mustapha, Zainal Arifin

    2013-12-01

    Mother-offspring interaction begins before birth. The foetus is particularly vulnerable to environmental insults and stress. The body responds by releasing excess of the stress hormone cortisol, which acts on glucocorticoid receptors. Hippocampus in the brain is rich in glucocorticoid receptors and therefore susceptible to stress. The stress effects are reduced when the animals are placed under a model wooden pyramid. The present study was to first explore the effects of prenatal restraint-stress on the plasma corticosterone levels and the dendritic arborisation of CA3 pyramidal neurons in the hippocampus of the offspring. Further, to test whether the pyramid environment would alter these effects, as housing under a pyramid is known to reduce the stress effects, pregnant Sprague Dawley rats were restrained for 9 h per day from gestation day 7 until parturition in a wire-mesh restrainer. Plasma corticosterone levels were found to be significantly increased. In addition, there was a significant reduction in the apical and the basal total dendritic branching points and intersections of the CA3 hippocampal pyramidal neurons. The results thus suggest that, housing in the pyramid dramatically reduces prenatal stress effects in rats.

  11. Active dendrites support efficient initiation of dendritic spikes in hippocampal CA3 pyramidal neurons

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    Kim, Sooyun; Guzman, Segundo J.; Hu, Hua; Jonas, Peter

    2012-01-01

    CA3 pyramidal neurons are important for memory formation and pattern completion in the hippocampal network. It is generally thought that proximal synapses from the mossy fibers activate these neurons most efficiently, whereas distal inputs from the perforant path have a weaker modulatory influence. We used confocally targeted patch-clamp recording from dendrites and axons to map the activation of rat CA3 pyramidal neurons at the subcellular level. Our results reveal two distinct dendritic dom...

  12. EFFECTS OF GLUTAMATE ON SODIUM CHANNEL IN ACUTELY DISSOCIATED HIPPOCAMPAL CA1 PYRAMIDAL NEURONS OF RATS

    Institute of Scientific and Technical Information of China (English)

    高宾丽; 伍国锋; 杨艳; 刘智飞; 曾晓荣

    2011-01-01

    Objective To observe the effects of glutamate on sodium channel in acutely dissociated hippocampal CA1 pyramidal neurons of rats.Methods Voltage-dependent sodium currents (INa) in acutely dissociated hippocampal CA1 pyramidal neurons of neonate rats were recorded by whole-cell patchclamp of the brain slice technique when a series of doses of glutamate (100-1000μmol/L) were applied.Results Different concentrations of glutamate could inhibit INa,and higher concentration of glutamate affected greater inhibitio...

  13. Modelling the Somatic Electrical Response of Hippocampal Pyramidal Neurons

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    1989-09-01

    non-linear, time-varying conductances in the soma, including those that underly three putative sodium currents , (IN.-tr,, INa-tail, and INa-rep), a...for excitation and propagation of the nerve impulse. Biophysics Journal. 6:, 1966. [12] C. French and P. Gage. A threshold sodium current in pyramidal

  14. Electrophysiological actions of cyclosporin A and tacrolimus on rat hip-pocampal CA1 pyramidal neurons

    Institute of Scientific and Technical Information of China (English)

    Yong YU; Xue-qin CHEN; Yao-yuan CUI; Guo-yuan HU

    2007-01-01

    Aim: The aim of the present study was to investigate the electrophysiological actions of cyclosporin A (CsA) and tacrolimus (FK506) on neurons in the brain, and to elucidate the relevant mechanisms. Methods: Whole-cell current-clamp recording was made in CA1 pyramidal neurons in rat hippocampal slices; whole- cell voltage-clamp recording was made in dissociated hippocampal CA1 pyrami- dal neurons of rats. Results: CsA (100 μmol/L) and FKS06 (50 μmol/L) did not significantly alter the passive electrical properties of hippocampal CA1 pyramidal neurons, but slowed down the repolarizing phase of the action potential. CsA (10-100 μmol/L) selectively inhibited the delayed rectifier K~ current (IK,) in a concentration-dependent manner. CsA did not affect the kinetic properties of IK. Intracellular dialysis of CsA (100 μmol/L) had no effect on IK. The inhibition of IK by CsA (100/μmol/L) persisted under the low Ca2+ conditions that blocked the basal activity of calcineurin. Conclusion: CsA exerted calcineurin-independent inhibition on the IK in rat hippocampal pyramidal neurons. Taken together with our previous finding with FK506, it is conceivable that the spike broadening caused by the immunosuppressant drugs is due to direct inhibition on the IK.

  15. Effects of organophosphates on rabbit pyramidal cells firing pattern and hippocampal theta rhythm.

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    Nio, J; Breton, P

    1994-01-01

    The effects of the irreversible acetylcholinesterase (AChE) antagonist paraoxon (Px) on hippocampal neurophysiology were investigated and compared to those of physostigmine in urethane-anaesthetized rabbits. Hippocampal CA1 EEG signals were analyzed by power spectra. Following intracarotid administration, the two drugs induced a similar fundamental low-frequency theta power peak while the appearance of a second theta harmonic was commonly found under Px. Again, inhibition of CA1 pyramidal cells firing was significantly more pronounced after Px injection than after physostigmine. A potent inhibitory action was also described following local Px iontophoretic application. However, a discrepancy appeared between the effects of Px and the classical cholinergic drugs (acetylcholine, physostigmine). The results indicate that Px and physostigmine have a rather similar influence on the septo-hippocampal pathway and support suggestions that Px could act within local hippocampal circuitry through other systems than the cholinergic system exclusively.

  16. Ethanol induces MAP2 changes in organotypic hippocampal slice cultures

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    Noraberg, J; Zimmer, J

    1998-01-01

    Microtubule-associated protein 2 (MAP2) and neuron-specific protein (NeuN) immunostains were used to demonstrate neurotoxic effects in mature hippocampal slice cultures exposed to ethanol (50, 100, 200 mM) for 4 weeks. At the low dose the density of MAP2 immunostaining in the dentate molecular...... layer was 118% of the control cultures, with no detectable changes in CA1 and CA3. At 100 mM no changes were detected, while 200 mM ethanol significantly reduced the MAP2 density in both dentate (19%) and hippocampal dendritic fields (CA3, 52%; CA1, 55%). At this dose NeuN staining showed considerable...... loss of CA3 pyramidal cells and moderate loss of dentate granule cells, as seen in vivo. The results indicate that brain slice cultures combined with immunostaining for cytoskeleton and neuronal markers can be used for studies of ethanol and organic solvent neurotoxicity....

  17. Ethanol induces MAP2 changes in organotypic hippocampal slice cultures

    DEFF Research Database (Denmark)

    Noraberg, J; Zimmer, J

    1998-01-01

    loss of CA3 pyramidal cells and moderate loss of dentate granule cells, as seen in vivo. The results indicate that brain slice cultures combined with immunostaining for cytoskeleton and neuronal markers can be used for studies of ethanol and organic solvent neurotoxicity.......Microtubule-associated protein 2 (MAP2) and neuron-specific protein (NeuN) immunostains were used to demonstrate neurotoxic effects in mature hippocampal slice cultures exposed to ethanol (50, 100, 200 mM) for 4 weeks. At the low dose the density of MAP2 immunostaining in the dentate molecular...... layer was 118% of the control cultures, with no detectable changes in CA1 and CA3. At 100 mM no changes were detected, while 200 mM ethanol significantly reduced the MAP2 density in both dentate (19%) and hippocampal dendritic fields (CA3, 52%; CA1, 55%). At this dose NeuN staining showed considerable...

  18. Phase precession in hippocampal interneurons showing strong functional coupling to individual pyramidal cells.

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    Maurer, Andrew P; Cowen, Stephen L; Burke, Sara N; Barnes, Carol A; McNaughton, Bruce L

    2006-12-27

    Although hippocampal interneurons typically do not show discrete regions of elevated firing in an environment, such as seen in pyramidal cell place fields, they do exhibit significant spatial modulation (McNaughton et al., 1983a). Strong monosynaptic coupling between pyramidal neurons and nearby interneurons in the CA1 stratum pyramidale has been strongly implicated on the basis of significant, short-latency peaks in cross-correlogram plots (Csicsvari et al., 1998). Furthermore, interneurons receiving a putative monosynaptic connection from a simultaneously recorded pyramidal cell appear to inherit the spatial modulation of the latter (Marshall et al., 2002). Buzsaki and colleagues hypothesize that interneurons may also adopt the firing phase dynamics of their afferent place cells, which show a phase shift relative to the hippocampal theta rhythm as a rat passes through the place field ("phase precession"). This study confirms and extends the previous reports by showing that interneurons in the dorsal and middle hippocampus with putative monosynaptic connections with place cells recorded on the same tetrode share other properties with their pyramidal cell afferents, including the spatial scale of the place field of pyramidal cell, a characteristic of the septotemporal level of the hippocampus from which the cells are recorded, and the rate of phase precession, which is slower in middle regions. Furthermore, variations in pyramidal cell place field scale within each septotemporal level attributable to task variations are similarly associated with variations in interneuron place field scale. The available data strongly suggest that spatial selectivity of CA1 stratum pyramidale interneurons is inherited from a small cluster of local pyramidal cells and is not a consequence of spatially selective synaptic input from CA3 or other sources.

  19. Somatosensory stimulation suppresses the excitability of pyramidal cells in the hippocampal CA1 region in rats

    Institute of Scientific and Technical Information of China (English)

    Yang Wang; Zhouyan Feng; Jing Wang; Xiaojing Zheng

    2014-01-01

    The hippocampal region of the brain is important for encoding environment inputs and memory formation. However, the underlying mechanisms are unclear. To investigate the behavior of indi-vidual neurons in response to somatosensory inputs in the hippocampal CA1 region, we recorded and analyzed changes in local ifeld potentials and the ifring rates of individual pyramidal cells and interneurons during tail clamping in urethane-anesthetized rats. We also explored the mechanisms underlying the neuronal responses. Somatosensory stimulation, in the form of tail clamping, chan-ged local ifeld potentials into theta rhythm-dominated waveforms, decreased the spike ifring of py-ramidal cells, and increased interneuron ifring. In addition, somatosensory stimulation attenuated orthodromic-evoked population spikes. These results suggest that somatosensory stimulation sup-presses the excitability of pyramidal cells in the hippocampal CA1 region. Increased inhibition by local interneurons might underlie this effect. These ifndings provide insight into the mechanisms of signal processing in the hippocampus and suggest that sensory stimulation might have thera-peutic potential for brain disorders associated with neuronal hyperexcitability.

  20. Hyperexcitability and cell loss in kainate-treated hippocampal slice cultures

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    Benedikz, Eirikur; Casaccia-Bonnefil, P; Stelzer, A

    1993-01-01

    Loss of hippocampal interneurons has been reported in patients with severe temporal lobe epilepsy and in animals treated with kainate. We investigated the relationship between KA induced epileptiform discharge and loss of interneurons in hippocampal slice cultures. Application of KA (1 micro......M) produced reversible epileptiform discharge without neurotoxicity. KA (5 microM), in contrast, produced irreversible epileptiform discharge and neurotoxicity, suggesting that the irreversible epileptiform discharge was required for the neuronal loss. Loss of CA3 pyramidal cells and parvalbumin...

  1. Hyperforin modulates dendritic spine morphology in hippocampal pyramidal neurons by activating Ca(2+) -permeable TRPC6 channels.

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    Leuner, Kristina; Li, Wei; Amaral, Michelle D; Rudolph, Stephanie; Calfa, Gaston; Schuwald, Anita M; Harteneck, Christian; Inoue, Takafumi; Pozzo-Miller, Lucas

    2013-01-01

    The standardized extract of the St. John's wort plant (Hypericum perforatum) is commonly used to treat mild to moderate depression. Its active constituent is hyperforin, a phloroglucinol derivative that reduces the reuptake of serotonin and norepinephrine by increasing intracellular Na(+) concentration through the activation of nonselective cationic TRPC6 channels. TRPC6 channels are also Ca(2+) -permeable, resulting in intracellular Ca(2+) elevations. Indeed, hyperforin activates TRPC6-mediated currents and Ca(2+) transients in rat PC12 cells, which induce their differentiation, mimicking the neurotrophic effect of nerve growth factor. Here, we show that hyperforin modulates dendritic spine morphology in CA1 and CA3 pyramidal neurons of hippocampal slice cultures through the activation of TRPC6 channels. Hyperforin also evoked intracellular Ca(2+) transients and depolarizing inward currents sensitive to the TRPC channel blocker La(3+) , thus resembling the actions of the neurotrophin brain-derived neurotrophic factor (BDNF) in hippocampal pyramidal neurons. These results suggest that the antidepressant actions of St. John's wort are mediated by a mechanism similar to that engaged by BDNF.

  2. AMPA receptor modulators have different impact on hippocampal pyramidal cells and interneurons.

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    Xia, Y-F; Arai, A C

    2005-01-01

    Positive modulators of AMPA receptors enhance synaptic plasticity and memory encoding. Facilitation of AMPA receptor currents not only results in enhanced activation of excitatory neurons but also increases the activity of inhibitory interneurons by up-modulating their excitatory input. However, little is known about the effects of these modulators on cells other than pyramidal neurons and about their impact on local microcircuits. This study examined the effects of members from three subfamilies of modulators (mainly CX516, CX546 and cyclothiazide) on excitatory synaptic responses in four classes of hippocampal CA1 neurons and on excitatory and disynaptically induced inhibitory field potentials in hippocampal slices. Effects on excitatory postsynaptic currents (EPSCs) were examined in pyramidal cells, in two types of inhibitory interneurons located in stratum radiatum and oriens, and in stratum radiatum giant cells, a novel type of excitatory neuron. With CX516, increases in EPSC amplitude in pyramidal cells were two to three times larger than in interneurons and six times larger than in radiatum giant cells. The effects of CX546 on response duration similarly were largest in pyramidal cells. However, this drug also strongly differentiated between stratum oriens and radiatum interneurons with increases being four times larger in the latter. In contrast, cyclothiazide had similar effects on response duration in all cell types. In field recordings, CX516 was several times more potent in enhancing excitatory postsynaptic potentials (EPSPs) than feedback or feedforward circuits, as expected from its larger influence on pyramidal cells. In contrast, BDP-20, a CX546 analog, was more potent in enhancing feedforward inhibition than either EPSPs or feedback inhibition. This preference for feedforward over feedback circuits is probably related to its higher potency in stratum radiatum versus oriens interneurons. Taken together, AMPA receptor modulators differ substantially

  3. Frequency-dependent signal processing in apical dendrites of hippocampal CA1 pyramidal cells.

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    Watanabe, H; Tsubokawa, H; Tsukada, M; Aihara, T

    2014-10-10

    Depending on an animal's behavioral state, hippocampal CA1 pyramidal cells receive distinct patterns of excitatory and inhibitory synaptic inputs. The time-dependent changes in the frequencies of these inputs and the nonuniform distribution of voltage-gated channels lead to dynamic fluctuations in membrane conductance. In this study, using a whole-cell patch-clamp method, we attempted to record and analyze the frequency dependencies of membrane responsiveness in Wistar rat hippocampal CA1 pyramidal cells following noise current injection directly into dendrites and somata under pharmacological blockade of all synaptic inputs. To estimate the frequency-dependent properties of membrane potential, membrane impedance was determined from the voltage response divided by the input current in the frequency domain. The cell membrane of most neurons showed low-pass filtering properties in all regions. In particular, the properties were strongly expressed in the somata or proximal dendrites. Moreover, the data revealed nonuniform distribution of dendritic impedance, which was high in the intermediate segment of the apical dendritic shaft (∼220-260μm from the soma). The low-pass filtering properties in the apical dendrites were more enhanced by membrane depolarization than those in the somata. Coherence spectral analysis revealed high coherence between the input signal and the output voltage response in the theta-gamma frequency range, and large lags emerged in the distal dendrites in the gamma frequency range. Our results suggest that apical dendrites of hippocampal CA1 pyramidal cells integrate synaptic inputs according to the frequency components of the input signal along the dendritic segments receiving the inputs.

  4. Intracellular activities related to in vitro hippocampal sharp waves are altered in CA3 pyramidal neurons of aged mice.

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    Moradi-Chameh, H; Peng, J; Wu, C; Zhang, L

    2014-09-26

    Pyramidal neurons in the hippocampal CA3 area interconnect intensively via recurrent axonal collaterals, and such CA3-to-CA3 recurrent circuitry plays important roles in the generation of hippocampal network activities. In particular, the CA3 circuitry is able to generate spontaneous sharp waves (SPWs) when examined in vitro. These in vitro SPWs are thought to result from the network activity of GABAergic inhibitory interneurons as SPW-correlating intracellular activities are featured with strong IPSPs in pyramidal neurons and EPSPs or spikes in GABAergic interneurons. In view of accumulating evidence indicating a decrease in subgroups of hippocampal GABAergic interneurons in aged animals, we test the hypothesis that the intracellular activities related to in vitro SPWs are altered in CA3 pyramidal neurons of aged mice. Hippocampal slices were prepared from adult and aged C57 black mice (ages 3-6 and 24-28months respectively). Population and single-cell activities were examined via extracellular and whole-cell patch-clamp recordings. CA3 SPW frequencies were not significantly different between the slices of adult and aged mice but SPW-correlating intracellular activities featured weaker IPSC components in aged CA3 pyramidal neurons compared to adult neurons. It was unlikely that this latter phenomenon was due to general impairments of GABAergic synapses in the aged CA3 circuitry as evoked IPSC responses and pharmacologically isolated IPSCs were observed in aged CA3 pyramidal neurons. In addition, aged CA3 pyramidal neurons displayed more positive resting potentials and had a higher propensity of burst firing than adult neurons. We postulate that alterations of GABAergic network activity may explain the reduced IPCS contributions to in vitro SPWs in aged CA3 pyramidal neurons. Overall, our present observations are supportive of the notion that excitability of hippocampal CA3 circuitry is increased in aged mice.

  5. Inhibition of a slow synaptic response by a metabotropic glutamate receptor antagonist in hippocampal CA3 pyramidal cells.

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    Gerber, U; Lüthi, A; Gähwiler, B H

    1993-11-22

    The effects of a novel antagonist of metabotropic glutamate receptors were investigated in CA3 pyramidal cells in hippocampal slice cultures of the rat. Earlier experiments showed that selective activation of metabotropic glutamate receptors with low concentrations of an agonist, 1S, 3R-1-amino-cyclopentane-1,3-dicarboxylic acid (ACPD), induced an inward current associated with a decrease in membrane conductance and inhibition of the slow calcium-dependent potassium current. These responses were strongly and reversibly reduced by the antagonist, (RS)-alpha-methyl-4-carboxyphenylglycine (MCPG, 0.5-1 mM). In the presence of antagonists of ionotropic glutamate receptors, stimulation of the afferent mossy fibres evoked postsynaptic responses in CA3 pyramidal cells which paralleled those observed with exogenously applied metabotropic glutamate receptor agonists, i.e. a slow inward current and a reduction of calcium-dependent potassium current. Both responses were greatly reduced by bath-applied MCPG (1 mM). These results show that MCPG acts as an effective antagonist at metabotropic glutamate receptors coupled to potassium conductances in the hippocampus. Furthermore, they confirm that glutamate release from presynaptic terminals can modulate postsynaptic properties by activation of metabotropic glutamate receptors.

  6. Extracellular calcium modulates persistent sodium current-dependent burst-firing in hippocampal pyramidal neurons.

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    Su, H; Alroy, G; Kirson, E D; Yaari, Y

    2001-06-15

    The generation of high-frequency spike bursts ("complex spikes"), either spontaneously or in response to depolarizing stimuli applied to the soma, is a notable feature in intracellular recordings from hippocampal CA1 pyramidal cells (PCs) in vivo. There is compelling evidence that the bursts are intrinsically generated by summation of large spike afterdepolarizations (ADPs). Using intracellular recordings in adult rat hippocampal slices, we show that intrinsic burst-firing in CA1 PCs is strongly dependent on the extracellular concentration of Ca(2+) ([Ca(2+)](o)). Thus, lowering [Ca(2+)](o) (by equimolar substitution with Mn(2+) or Mg(2+)) induced intrinsic bursting in nonbursters, whereas raising [Ca(2+)](o) suppressed intrinsic bursting in native bursters. The induction of intrinsic bursting by low [Ca(2+)](o) was associated with enlargement of the spike ADP. Low [Ca(2+)](o)-induced intrinsic bursts and their underlying ADPs were suppressed by drugs that reduce the persistent Na(+) current (I(NaP)), indicating that this current mediates the slow burst depolarization. Blocking Ca(2+)-activated K(+) currents with extracellular Ni(2+) or intracellular chelation of Ca(2+) did not induce intrinsic bursting. This and other evidence suggest that lowering [Ca(2+)](o) may induce intrinsic bursting by augmenting I(NaP). Because repetitive neuronal activity in the hippocampus is associated with marked decreases in [Ca(2+)](o), the regulation of intrinsic bursting by extracellular Ca(2+) may provide a mechanism for preferential recruitment of this firing mode during certain forms of hippocampal activation.

  7. ERK1/2 Activation Is Necessary for BDNF to Increase Dendritic Spine Density in Hippocampal CA1 Pyramidal Neurons

    Science.gov (United States)

    Alonso, Mariana; Medina, Jorge H.; Pozzo-Miller, Lucas

    2004-01-01

    Brain-derived neurotrophic factor (BDNF) is a potent modulator of synaptic transmission and plasticity in the CNS, acting both pre- and postsynaptically. We demonstrated recently that BDNF/TrkB signaling increases dendritic spine density in hippocampal CA1 pyramidal neurons. Here, we tested whether activation of the prominent ERK (MAPK) signaling…

  8. Effect of etomidate on voltage-dependent potassium currents in rat isolated hippocampal pyramidal neurons

    Institute of Scientific and Technical Information of China (English)

    TAN Hong-yu; SUN Li-na; WANG Xiao-liang; YE Tie-hu

    2010-01-01

    Background Previous studies demonstrated general anesthetics affect potassium ion channels, which may be one of the mechanisms of general anesthesia. Because the effect of etomidate on potassium channels in rat hippocampus which is involved in memory function has not been studied, we investigated the effects of etomidate on both delayed rectifier potassium current (I_((K(DR))) and transient outward potassium current (I_((K(A))) in acutely dissociated rat hippocampal pyramidal neurons.Methods Single rat hippocampal pyramidal neurons from male Wistar rats of 7-10 days were acutely dissociated by enzymatic digestion and mechanical dispersion according to the methods of Kay and Wong with slight modification. Voltage-clamp recordings were performed in the whole-cell patch clamp configuration. Currents were recorded with a List EPC-10 amplifier and data were stored in a computer using Pulse 8.5. Student's paired two-tail t test was used for data analysis. Results At the concentration of 100 μmol/L, etomidate significantly inhibited I_(K(DR)) by 49.2% at +40 mV when depolarized from -110 mV (P 0.05). The IC_(50) value of etomidate for blocking I_(K(DR)) was calculated as 5.4 μmol/L, with a Hill slope of 2.45. At the presence of 10 μmol/L etomidate, the V_(1/2) of activation curve was shifted from (17.3±1.5) mV to (10.7±9.9) mV (n=8, P <0.05), the V_(1/2) of inactivation curve was shifted from (-18.3±2.2) mV to (-45.3±9.4) mV (n=8, P <0.05). Etomidate 10 μmol/L shifted both the activation curve and inactivation curve of I_(K(DR)) to negative potential, but mainly affected the inactivation kinetics.Conclusions Etomidate potently inhibited I_(K(DR)) but not I_(K(A)) in rat hippocampal pyramidal neurons. I_(K(DR)) was inhibited by etomidate in a concentration-dependent manner, while I_(K(A)) remained unaffected.

  9. Phorbol esters broaden the action potential in CA1 hippocampal pyramidal cells.

    Science.gov (United States)

    Storm, J F

    1987-03-20

    Intracellular recordings were made from CA1 pyramidal cells in rat hippocampal slices. Single action potentials were elicited by injection of brief current pulses. Bath application of phorbol esters (4 beta-phorbol-12,13-diacetate, 0.3-5 microM; or 4 beta-phorbol-12,13-dibutyrate, 5-10 microM) broadened the action potential in each of the cells tested (n = 9). The broadening reflected slowing of the repolarization, whereas the upstroke of the spike was unchanged. This effect may enhance transmitter release from synaptic terminals, and contribute to enhancement of synaptic transmission through activation of protein kinase C, a mechanism which has been associated with long term potentiation.

  10. Membrane Potential Dynamics of CA1 Pyramidal Neurons during Hippocampal Ripples in Awake Mice.

    Science.gov (United States)

    Hulse, Brad K; Moreaux, Laurent C; Lubenov, Evgueniy V; Siapas, Athanassios G

    2016-02-17

    Ripples are high-frequency oscillations associated with population bursts in area CA1 of the hippocampus that play a prominent role in theories of memory consolidation. While spiking during ripples has been extensively studied, our understanding of the subthreshold behavior of hippocampal neurons during these events remains incomplete. Here, we combine in vivo whole-cell and multisite extracellular recordings to characterize the membrane potential dynamics of identified CA1 pyramidal neurons during ripples. We find that the subthreshold depolarization during ripples is uncorrelated with the net excitatory input to CA1, while the post-ripple hyperpolarization varies proportionately. This clarifies the circuit mechanism keeping most neurons silent during ripples. On a finer timescale, the phase delay between intracellular and extracellular ripple oscillations varies systematically with membrane potential. Such smoothly varying delays are inconsistent with models of intracellular ripple generation involving perisomatic inhibition alone. Instead, they suggest that ripple-frequency excitation leading inhibition shapes intracellular ripple oscillations.

  11. Ammonia inhibits long-term potentiation via neurosteroid synthesis in hippocampal pyramidal neurons.

    Science.gov (United States)

    Izumi, Y; Svrakic, N; O'Dell, K; Zorumski, C F

    2013-03-13

    Neurosteroids are a class of endogenous steroids synthesized in the brain that are believed to be involved in the pathogenesis of neuropsychiatric disorders and memory impairment. Ammonia impairs long-term potentiation (LTP), a synaptic model of learning, in the hippocampus, a brain region involved in memory acquisition. Although mechanisms underlying ammonia-mediated LTP inhibition are not fully understood, we previously found that the activation of N-methyl-d-aspartate receptors (NMDARs) is important. Based on this, we hypothesize that metabolic stressors, including hyperammonemia, promote untimely NMDAR activation and result in neural adaptations that include the synthesis of allopregnanolone (alloP) and other GABA-potentiating neurosteroids that dampen neuronal activity and impair LTP and memory formation. Using an antibody against 5α-reduced neurosteroids, we found that 100 μM ammonia acutely enhanced neurosteroid immunostaining in pyramidal neurons in the CA1 region of rat hippocampal slices. The enhanced staining was blocked by finasteride, a selective inhibitor of 5α-reductase, a key enzyme required for alloP synthesis. Finasteride also overcame LTP inhibition by 100 μM ammonia, as did picrotoxin, an inhibitor of GABA-A receptors. These results indicate that GABA-enhancing neurosteroids, synthesized locally within pyramidal neurons, contribute significantly to ammonia-mediated synaptic dysfunction. These results suggest that the manipulation of neurosteroid synthesis could provide a strategy to improve cognitive function in individuals with hyperammonemia.

  12. Transient increase in Zn2+ in hippocampal CA1 pyramidal neurons causes reversible memory deficit.

    Directory of Open Access Journals (Sweden)

    Atsushi Takeda

    Full Text Available The translocation of synaptic Zn(2+ to the cytosolic compartment has been studied to understand Zn(2+ neurotoxicity in neurological diseases. However, it is unknown whether the moderate increase in Zn(2+ in the cytosolic compartment affects memory processing in the hippocampus. In the present study, the moderate increase in cytosolic Zn(2+ in the hippocampus was induced with clioquinol (CQ, a zinc ionophore. Zn(2+ delivery by Zn-CQ transiently attenuated CA1 long-term potentiation (LTP in hippocampal slices prepared 2 h after i.p. injection of Zn-CQ into rats, when intracellular Zn(2+ levels was transiently increased in the CA1 pyramidal cell layer, followed by object recognition memory deficit. Object recognition memory was transiently impaired 30 min after injection of ZnCl(2 into the CA1, but not after injection into the dentate gyrus that did not significantly increase intracellular Zn(2+ in the granule cell layer of the dentate gyrus. Object recognition memory deficit may be linked to the preferential increase in Zn(2+ and/or the preferential vulnerability to Zn(2+ in CA1 pyramidal neurons. In the case of the cytosolic increase in endogenous Zn(2+ in the CA1 induced by 100 mM KCl, furthermore, object recognition memory was also transiently impaired, while ameliorated by co-injection of CaEDTA to block the increase in cytosolic Zn(2+. The present study indicates that the transient increase in cytosolic Zn(2+ in CA1 pyramidal neurons reversibly impairs object recognition memory.

  13. 76 FR 15358 - Culturally Significant Objects Imported for Exhibition Determinations: “Before the Pyramids: The...

    Science.gov (United States)

    2011-03-21

    ... ``Before the Pyramids: The Origins of Egyptian Civilization'' imported from abroad for temporary exhibition... Culturally Significant Objects Imported for Exhibition Determinations: ``Before the Pyramids: The Origins of Egyptian Civilization'' SUMMARY: Notice is hereby given of the following determinations: Pursuant to...

  14. Hippocampal pyramidal neurons switch from a multipolar migration mode to a novel "climbing" migration mode during development.

    Science.gov (United States)

    Kitazawa, Ayako; Kubo, Ken-ichiro; Hayashi, Kanehiro; Matsunaga, Yuki; Ishii, Kazuhiro; Nakajima, Kazunori

    2014-01-22

    The hippocampus plays important roles in brain functions. Despite the importance of hippocampal functions, recent analyses of neuronal migration have mainly been performed on the cerebral neocortex, and the cellular mechanisms responsible for the formation of the hippocampus are not yet completely understood. Moreover, why a prolonged time is required for hippocampal neurons to complete their migration has been unexplainable for several decades. We analyzed the migratory profile of neurons in the developing mouse hippocampal CA1 region and found that the hippocampal pyramidal neurons generated near the ventricle became postmitotic multipolar cells and accumulated in the multipolar cell accumulation zone (MAZ) in the late stage of development. The hippocampal neurons passed through the pyramidal layer by a unique mode of migration. Their leading processes were highly branched and made contact with many radial fibers. Time-lapse imaging revealed that the migrating cells changed their scaffolds from the original radial fibers to other radial fibers, and as a result they proceed in a zigzag manner, with long intervals. The migrating cells in the hippocampus reminded us of "rock climbers" that instead of using their hands to pull up their bodies were using their leading processes to pull up their cell bodies. Because this mode of migration had never been described, we called it the "climbing" mode. The change from the "climbing" mode in the hippocampus to the "locomotion" mode in the neocortex may have contributed to the brain expansion during evolution.

  15. Muscarinic activation of inwardly rectifying K+ conductance reduces EPSPs in rat hippocampal CA1 pyramidal cells

    Science.gov (United States)

    Seeger, Thomas; Alzheimer, Christian

    2001-01-01

    To determine how acetylcholine (ACh) modulates the somatodendritic processing of EPSPs, we performed whole-cell recordings from CA1 pyramidal cells of hippocampal slices and examined the effect of the cholinergic agonist, carbachol (CCh), on α-amino-3-hydroxy-5-methyl isoxazole-4-propionate (AMPA) EPSPs, miniature EPSPs, and EPSP-like waveforms evoked by brief dendritic glutamate pulses (glutamate-evoked postsynaptic potentials, GPSPs). Although CCh is known to enhance the intrinsic excitability of the neuron in several ways, activation of atropine-sensitive (muscarinic) receptors on the apical dendrite or the soma of CA1 pyramidal cells consistently reduced the amplitude of EPSPs and GPSPs. Cholinergic inhibition of evoked and simulated EPSP waveforms displayed considerable voltage dependence, with the amplitude of the postsynaptic potentials progressively declining with membrane hyperpolarization indicating the involvement of an inwardly rectifying current. Extracellular Ba2+ (200 μm) and tertiapin (30 nm), a novel and selective blocker of G protein-activated, inwardly rectifying K+ (GIRK) channels, completely blocked the effect of CCh on GPSP amplitude. Muscarinic reduction of GPSPs was not sensitive to the M1 receptor-preferring antagonist, pirenzepine, but was suppressed by the M2 receptor-preferring antagonist, methoctramine, and by the allosteric M2 receptor antagonist, gallamine. In voltage-clamp recordings, CCh induced an ion current displaying inward rectification in the hyperpolarizing direction, which was identified as a GIRK current based on its sensitivity to low Ba2+ and tertiapin. Its pharmacological profile paralleled that of the cholinergic GPSP reduction. We link the observed reduction of postsynaptic potentials to the cholinergic activation of a GIRK conductance, which serves to partially shunt excitatory synaptic input. PMID:11533131

  16. Repeated transcranial magnetic stimulation prevents kindling-induced changes in electrophysiological properties of rat hippocampal CA1 pyramidal neurons.

    Science.gov (United States)

    Shojaei, A; Semnanian, S; Janahmadi, M; Moradi-Chameh, H; Firoozabadi, S M; Mirnajafi-Zadeh, J

    2014-11-01

    The mechanisms underlying antiepileptic or antiepileptogenic effects of repeated transcranial magnetic stimulation (rTMS) are poorly understood. In this study, we investigated the effect of rTMS applied during rapid amygdala kindling on some electrophysiological properties of hippocampal CA1 pyramidal neurons. Male Wistar rats were kindled by daily electrical stimulation of the basolateral amygdala in a semi-rapid manner (12 stimulations/day) until they achieved stage-5 seizure. One group (kindled+rTMS (KrTMS)) of animals received rTMS (1Hz for 4min) 5min after termination of daily kindling stimulations. Twenty four hours following the last kindling stimulation electrophysiological properties of hippocampal CA1 pyramidal neurons were investigated using whole-cell patch-clamp technique. Amygdala kindling significantly depolarized the resting membrane potential and increased the input resistance, spontaneous firing activity, number of evoked spikes and half-width of the first evoked spike. Kindling also decreased the first-spike latency and amplitude significantly. Application of rTMS during kindling somehow prevented the development of seizures and protected CA1 pyramidal neurons of hippocampus against deleterious effect of kindling on both passive and active neuronal electrophysiological properties. Interestingly, application of rTMS alone enhanced the excitability of CA1 pyramidal neurons significantly. Based on the results of our study, it may be suggested that rTMS exerts its anticonvulsant effect, in part, through preventing the amygdala kindling-induced changes in electrophysiological properties of hippocampal CA1 pyramidal neurons. It seems that rTMS exerts protective effects on the neural circuits involved in spreading the seizures from the focus to other parts of the brain.

  17. Effects of lithium chloride on outward potassium currents in acutely isolated hippocampal CA1 pyramidal neurons

    Institute of Scientific and Technical Information of China (English)

    ZHANG Chaofeng; DU Huizhi; YANG Pin

    2006-01-01

    Although lithium possesses neuroprotective functions, the molecular mechanism underlying its actions has not been fully elucidated. In the present paper, the effects of lithium chloride on voltage-dependent potassium currents in the CA1 pyramidal neurons acutely isolated from rat hippocampus were studied using the whole-cell patch-clamp technique. Depolarizing test pulses activated two components of outward potassium currents: a rapidly activating and inactivating component, IA and a delayed component, IK. Results showed that lithium chloride increased the amplitude of IA in a concentration-dependent manner. Half enhancement concentration (EC50) was 22.80±5.45 μmol·L-1. Lithium chloride of 25 μmol·L-1 shifted the steady-state activation curve and inactivation curve of IA to more negative potentials, but mainly affected the activation kinetics. The amplitude and the activation processes of IK were not affected by lithium chloride. The effects of lithium chloride on potassium channel appear to possess neuroprotective properties by Ca2+-lowing effects modulate neuronal excitability by activating IA in rat hippocampal neurons.

  18. Persistent sodium current properties in hippocampal CA1 pyramidal neurons of young and adult rats.

    Science.gov (United States)

    Lunko, Oleksii; Isaev, Dmytro; Maximyuk, Oleksandr; Ivanchick, Gleb; Sydorenko, Vadym; Krishtal, Oleg; Isaeva, Elena

    2014-01-24

    Persistent tetrodotoxin-sensitive sodium current (INaP) plays an important role in cellular and neuronal network excitability in physiological conditions and under different pathological circumstances. However, developmental changes in INaP properties remain largely unclear. In the present study using whole cell patch clamp technique we evaluated INaP properties in CA1 hippocampal pyramidal neurons isolated from young (postnatal day (P) 12-16) and adult (P60-75) rats. We show that the INaP density is substantially larger in the adult group. Although INaP inactivation characteristics were found to be similar in both groups, voltage dependence of INaP activation is shifted to more negative membrane potentials (young: -48.6±0.5mV vs. adult: -52.4±0.2mV, p<0.01). Our data indicates the increase of INaP contribution in the basal membrane sodium conductivity in the mature hippocampus.

  19. Lead exposure impairs NMDA agonist-induced no production in pyramidal hippocampal cells

    Directory of Open Access Journals (Sweden)

    Seyed Nasser Ostad

    2006-03-01

    Full Text Available Chronic exposure to Lead (Pb affects neural functions in central nervous system (CNS particularly the learning and memory. On the other hand, alteration of calcium level in the CNS results in activation of NOS where it is expected to increase nitric oxide level in hippocampus. In this study the role of Lead exposure in NMDA induced NO production in pyramidal hippocampal cells (CA1HP was investigated. The NO level was determined by measurement of concentration of nitrite and nitrate as NO products using the metHb production at 401 nm. The ACBD (NMDA agonist-induced NO level was almost reduced to the control level (2.5 nM in the presence of 10 and 100 nM of Lead acetate. Lead acetate at concentrations which normally results in chronic toxicity did not increase the nitric oxide (NO production by CA1HP. One reason for this finding could be the interaction of Lead with NMDA receptors due to similarity of Pb2+ to Zn2+ ion. Another reason may be related to direct interaction of Lead with NMDA receptors that inhibit the stimulated NO production.

  20. Dendritic Na(+) spikes enable cortical input to drive action potential output from hippocampal CA2 pyramidal neurons.

    Science.gov (United States)

    Sun, Qian; Srinivas, Kalyan V; Sotayo, Alaba; Siegelbaum, Steven A

    2014-01-01

    Synaptic inputs from different brain areas are often targeted to distinct regions of neuronal dendritic arbors. Inputs to proximal dendrites usually produce large somatic EPSPs that efficiently trigger action potential (AP) output, whereas inputs to distal dendrites are greatly attenuated and may largely modulate AP output. In contrast to most other cortical and hippocampal neurons, hippocampal CA2 pyramidal neurons show unusually strong excitation by their distal dendritic inputs from entorhinal cortex (EC). In this study, we demonstrate that the ability of these EC inputs to drive CA2 AP output requires the firing of local dendritic Na(+) spikes. Furthermore, we find that CA2 dendritic geometry contributes to the efficient coupling of dendritic Na(+) spikes to AP output. These results provide a striking example of how dendritic spikes enable direct cortical inputs to overcome unfavorable distal synaptic locale to trigger axonal AP output and thereby enable efficient cortico-hippocampal information flow.

  1. Isolated hippocampal neurons in cryopreserved long-term cultures: development of neuroarchitecture and sensitivity to NMDA.

    Science.gov (United States)

    Mattson, M P; Kater, S B

    1988-01-01

    Isolated neurons in long-term culture provide a unique opportunity to address important problems in neuronal development. In the present study we established conditions for cryopreservation and long-term primary culture of isolated embryonic hippocampal neurons. This culture system was then used for initial characterizations of the development of neuroarchitecture and neurotransmitter response systems. Cryoprotection with 8% dimethylsulfoxide, slow freezing, and rapid thawing provided high-yield cultures which appeared normal in terms of cell types, mitotic ability, axonal and dendritic outgrowth, and sensitivity to glutamate neurotoxicity. A reduced medium volume and moderate elevation in extracellular K+ to 20 mM promoted survival of isolated neurons through 3 weeks of culture. The outgrowth of axons and dendrites in pyramidal-like neurons was found to differ over a 3-week culture period such that axons continued to grow at a relatively constant rate while dendritic outgrowth slowed during the second week and ceased by the end of week 3. Developmental changes were also observed in the sensitivity of pyramidal neurons to glutamate neurotoxicity; functional kainate/quisqualate receptors were present during the first week of culture, while responses to N-methyl-D-aspartic acid (NMDA) did not appear until the second week. The technologies for cryopreservation and long-term culture of isolated hippocampal neurons reported here provide a useful system in which to address a variety of problems in development neuroscience.

  2. Electrophysiological effects of SKF83959 on hippocampal CA1 pyramidal neurons: potential mechanisms for the drug's neuroprotective effects.

    Directory of Open Access Journals (Sweden)

    Hong-Yuan Chu

    Full Text Available Although the potent anti-parkinsonian action of the atypical D₁-like receptor agonist SKF83959 has been attributed to the selective activation of phosphoinositol(PI-linked D₁ receptor, whereas the mechanism underlying its potent neuroprotective effect is not fully understood. In the present study, the actions of SKF83959 on neuronal membrane potential and neuronal excitability were investigated in CA1 pyramidal neurons of rat hippocampal slices. SKF83959 (10-100 µM caused a concentration-dependent depolarization, associated with a reduction of input resistance in CA1 pyramidal neurons. The depolarization was blocked neither by antagonists for D₁, D₂, 5-HT(2A/2C receptors and α₁-adrenoceptor, nor by intracellular dialysis of GDP-β-S. However, the specific HCN channel blocker ZD7288 (10 µM antagonized both the depolarization and reduction of input resistance caused by SKF83959. In voltage-clamp experiments, SKF83959 (10-100 µM caused a concentration-dependent increase of Ih current in CA1 pyramidal neurons, which was independent of D₁ receptor activation. Moreover, SKF83959 (50 µM caused a 6 mV positive shift in the activation curve of Ih and significantly accelerated the activation of Ih current. In addition, SKF83959 also reduced the neuronal excitability of CA1 pyramidal neurons, which was manifested by the decrease in the number and amplitude of action potentials evoked by depolarizing currents, and by the increase of firing threshold and rhoebase current. The above results suggest that SKF83959 increased Ih current through a D₁ receptor-independent mechanism, which led to the depolarization of hippocampal CA1 pyramidal neurons. These findings provide a novel mechanism for the drug's neuroprotective effects, which may contributes to its therapeutic benefits in Parkinson's disease.

  3. Different patterns of synaptic transmission revealed between hippocampal CA3 stratum oriens and stratum lucidum interneurons and their pyramidal cell targets.

    Science.gov (United States)

    Aaron, G B; Wilcox, K S; Dichter, M A

    2003-01-01

    Stratum lucidum (SL) interneurons likely mediate feedforward inhibition between the dentate gyrus mossy fibers and CA3 pyramidal cells, while stratum oriens (SO) interneurons likely provide both feedforward and feedback inhibition within the CA3 commissural/associational network. Using dual whole-cell patch-clamp recordings between interneurons and CA3 pyramidal cells, we have examined SL and SO interneurons and their synapses within organotypic hippocampal slice cultures. Biocytin staining revealed different morphologies between these interneuron groups, both being very similar to those found previously in acute slices. The kinetics of IPSCs were similar between the two groups, but the reliability of synaptic transmission of SL interneuron (SL-INT) IPSCs was significantly lower than the virtually 100% reliability (non-existent failure rates) of SO-INT IPSCs. The SL-INT IPSCs also had a lower quantal content than the SO-INT IPSCs. In addition, SL-INTs were less likely than SO-INTs to innervate or to be innervated by nearby CA3 pyramidal cells. Paired-pulse stimulation at 100 ms interstimulus intervals produced similar paired-pulse depression in both interneuron synapses, despite the significantly higher failure rate of IPSCs produced by the SL-INTs compared with SO-INTs. CV analysis supported the hypothesis that paired-pulse depression was presynaptic. During repetitive, high frequency stimulation (>10 Hz for 500 ms) the two different synapses exhibited distinctly different forms of short-term plasticity: all SL interneurons displayed significant short-term facilitation (mean 113% facilitation, n=4), while, by contrast, SO interneuron synapses displayed either short-term depression (mean 42% depression, n=5 of 8) or no net facilitation or depression (n=3 of 8). These results indicate that the synaptic properties of interneurons can be quite different for interneurons in different hippocampal circuits.

  4. Staining protocol for organotypic hippocampal slice cultures.

    Science.gov (United States)

    Gogolla, Nadine; Galimberti, Ivan; DePaola, Vincenzo; Caroni, Pico

    2006-01-01

    This protocol details a method to immunostain organotypic slice cultures from mouse hippocampus. The cultures are based on the interface method, which does not require special equipment, is easy to execute and yields slice cultures that can be imaged repeatedly, from the time of isolation at postnatal day 6-9 up to 6 months in vitro. The preserved tissue architecture facilitates the analysis of defined hippocampal synapses, cells and entire projections. Time-lapse imaging is based on transgenes expressed in the mice or on constructs introduced through transfection or viral vectors; it can reveal processes that develop over periods ranging from seconds to months. Subsequent to imaging, the slices can be processed for immunocytochemistry to collect further information about the imaged structures. This protocol can be completed in 3 d.

  5. Cytosolic phospholipase A(2) alpha mediates electrophysiologic responses of hippocampal pyramidal neurons to neurotoxic NMDA treatment.

    Science.gov (United States)

    Shen, Ying; Kishimoto, Koji; Linden, David J; Sapirstein, Adam

    2007-04-03

    The arachidonic acid-generating enzyme cytosolic phospholipase A(2) alpha (cPLA(2)alpha) has been implicated in the progression of excitotoxic neuronal injury. However, the mechanisms of cPLA(2)alpha toxicity have yet to be determined. Here, we used a model system exposing mouse hippocampal slices to NMDA as an excitotoxic injury, in combination with simultaneous patch-clamp recording and confocal Ca(2+) imaging of CA1 pyramidal neurons. NMDA treatment caused significantly greater injury in wild-type (WT) than in cPLA(2)alpha null CA1 neurons. Bath application of NMDA evoked a slow inward current in voltage-clamped neurons (composed of both NMDA receptor-mediated and other conductances) that was smaller in cPLA(2)alpha null than in WT slices. This was not due to down-regulation of NMDA receptor function because NMDA receptor-mediated currents were equivalent in each genotype following brief photolysis of caged glutamate. Current-clamp recordings were made during and following NMDA exposure by eliciting a single action potential with a brief current injection. After NMDA exposure, WT CA1 neurons developed a spike-evoked plateau potential and an increased spike-evoked dendritic Ca(2+) transient. These effects were absent in CA1 neurons from cPLA(2)alpha null mice and WT neurons treated with a cPLA(2)alpha inhibitor. The Ca-sensitive K-channel toxins, apamin and paxilline, caused spike broadening and Ca(2+) enhancement in WT and cPLA(2)alpha null slices. NMDA application in WT and arachidonate applied to cPLA(2)alpha null cells occluded the effects of apamin/paxilline. These results indicate that cPLA(2)alpha activity is required for development of aberrant electrophysiologic events triggered by NMDA receptor activation, in part through attenuation of K-channel function.

  6. Adenosine actions on CA1 pyramidal neurones in rat hippocampal slices.

    Science.gov (United States)

    Greene, R W; Haas, H L

    1985-09-01

    Intracellular recordings with a bridge amplifier of CA1 pyramidal neurones in vitro were employed to study the mechanisms of action of exogenously applied adenosine in the hippocampal slice preparation of the rat. Adenosine enhanced the calcium-dependent, long-duration after-hyperpolarization (a.h.p.) at least in part by a reduction in the rate of decay of the a.h.p. Both the reduced rate of decay and that of the control can be described with a single exponential. Antagonism of the calcium-dependent potassium current (and as a result, the a.h.p.) by bath application of CdCl2 or intracellular injection of EGTA (ethyleneglycolbis-(beta-aminoethyl ether)N,N'-tetraacetic acid) did not reduce the adenosine-evoked hyperpolarization or decrease in input resistance. Similarly, TEA (tetraethylammonium), which antagonizes both the voltage- and calcium-sensitive, delayed, outward rectification, had no effect on the adenosine-evoked changes in resting membrane properties. Adenosine did not affect the early, transient, outward rectification. During exposure to 4-aminopyridine (4-AP) in concentrations sufficient to antagonize this early rectification, the changes in resting membrane properties evoked by adenosine were unaffected. We conclude that the enhancement of the a.h.p. and accommodation by adenosine may be mediated by a change in the regulation of intracellular calcium. However, the mechanism responsible for the hyperpolarization and decrease in input resistance evoked by adenosine is both calcium and voltage insensitive. Thus, it appears distinct from that mediating the enhancement of the a.h.p. and accommodation.

  7. Distinct axo-somato-dendritic distributions of three potassium channels in CA1 hippocampal pyramidal cells.

    Science.gov (United States)

    Kirizs, Tekla; Kerti-Szigeti, Katalin; Lorincz, Andrea; Nusser, Zoltan

    2014-06-01

    Potassium channels comprise the most diverse family of ion channels and play critical roles in a large variety of physiological and pathological processes. In addition to their molecular diversity, variations in their distributions and densities on the axo-somato-dendritic surface of neurons are key parameters in determining their functional impact. Despite extensive electrophysiological and anatomical investigations, the exact location and densities of most K(+) channels in small subcellular compartments are still unknown. Here we aimed at providing a quantitative surface map of two delayed-rectifier (Kv1.1 and Kv2.1) and one G-protein-gated inwardly rectifying (Kir3.2) K(+) channel subunits on hippocampal CA1 pyramidal cells (PCs). Freeze-fracture replica immunogold labelling was employed to determine the relative densities of these K(+) channel subunits in 18 axo-somato-dendritic compartments. Significant densities of the Kv1.1 subunit were detected on axon initial segments (AISs) and axon terminals, with an approximately eight-fold lower density in the latter compartment. The Kv2.1 subunit was found in somatic, proximal dendritic and AIS plasma membranes at approximately the same densities. This subunit has a non-uniform plasma membrane distribution; Kv2.1 clusters are frequently adjacent to, but never overlap with, GABAergic synapses. A quasi-linear increase in the Kir3.2 subunit density along the dendrites of PCs was detected, showing no significant difference between apical dendritic shafts, oblique dendrites or dendritic spines at the same distance from the soma. Our results demonstrate that each subunit has a unique cell-surface distribution pattern, and predict their differential involvement in synaptic integration and output generation at distinct subcellular compartments.

  8. Adenosine A1 Receptor Suppresses Tonic GABAA Receptor Currents in Hippocampal Pyramidal Cells and in a Defined Subpopulation of Interneurons.

    Science.gov (United States)

    Rombo, Diogo M; Dias, Raquel B; Duarte, Sofia T; Ribeiro, Joaquim A; Lamsa, Karri P; Sebastião, Ana M

    2016-03-01

    Adenosine is an endogenous neuromodulator that decreases excitability of hippocampal circuits activating membrane-bound metabotropic A1 receptor (A1R). The presynaptic inhibitory action of adenosine A1R in glutamatergic synapses is well documented, but its influence on inhibitory GABAergic transmission is poorly known. We report that GABAA receptor (GABAAR)-mediated tonic, but not phasic, transmission is suppressed by A1R in hippocampal neurons. Adenosine A1R activation strongly inhibits GABAAR agonist (muscimol)-evoked currents in Cornu Ammonis 1 (CA1) pyramidal neurons and in a specific subpopulation of interneurons expressing axonal cannabinoid receptor type 1. In addition, A1R suppresses tonic GABAAR currents measured in the presence of elevated ambient GABA as well as in naïve slices. The inhibition of GABAergic currents involves both protein kinase A (PKA) and protein kinase C (PKC) signaling pathways and decreases GABAAR δ-subunit expression. On the contrary, no A1R-mediated modulation was detected in phasic inhibitory postsynaptic currents evoked either by afferent electrical stimulation or by spontaneous quantal release. The results show that A1R modulates extrasynaptic rather than synaptic GABAAR-mediated signaling, and that this modulation selectively occurs in hippocampal pyramidal neurons and in a specific subpopulation of inhibitory interneurons. We conclude that modulation of tonic GABAAR signaling by adenosine A1R in specific neuron types may regulate neuronal gain and excitability in the hippocampus.

  9. Whole-cell recordings of voltage-gated Calcium, Potassium and Sodium currents in acutely isolated hippocampal pyramidal neurons

    Institute of Scientific and Technical Information of China (English)

    Shuyun Huang; Qing Cai; Weitian Liu; Xiaoling Wang; Tao Wang

    2009-01-01

    Objective:To record Calcium, Potassium and Sodium currents in acutely isolated hippocampal pyramidal neurons. Methods:Hip-pocampal CA3 neurons were freshly isolated by 1 mg protease/3 ml SES and mechanical trituration with polished pipettes of progressively smaller tip diameters. Patch clamp technique in whole-cell mode was employed to record voltage-gated channel currents. Results:The procedure dissociated hippocampal neurons, preserving apical dendrites and several basal dendrites, without impairing the electrical characteristics of the neurons. Whole-cell patch clamp configuration was successfully used to record voltage-gated Ca2+ currents, delayed rectifier K+ current and voltage-gated Na+ currents. Conclusion:Protease combined with mechanical trituration may be used for the dissociation of neurons from rat hippocampus. Voltage-gated channels currents could be recorded using a patch clamp technique.

  10. Simultaneous activation of gamma and theta network oscillations in rat hippocampal slice cultures.

    Science.gov (United States)

    Fischer, Yacov; Wittner, Lucia; Freund, Tamas F; Gähwiler, Beat H

    2002-03-15

    Hippocampal activity in vivo is characterized by concurrent oscillations at theta (4-15 Hz) and gamma (20-80 Hz) frequencies. Here we show that cholinergic receptor activation (methacholine 10-20 nm) in hippocampal slice cultures induces an oscillatory mode of activity, in which the intrinsic network oscillator (located in the CA3 area) expresses simultaneous theta and gamma network oscillations. Pyramidal cells display synaptic theta oscillations, characterized by cycles consisting of population EPSP-IPSP sequences that are dominated by population IPSPs. These rhythmic IPSPs most probably result from theta-modulated spiking activity of several interneurons. At the same time, the majority of interneurons consistently display synaptic gamma oscillations. These oscillatory cycles consist of fast depolarizing rhythmic events that are likely to reflect excitatory input from CA3 pyramidal cells. Interneurons comprising this functional group were identified morphologically. They include four known types of interneurons (basket, O-LM, bistratified and str. lucidum-specific cells) and one new type of CA3 interneuron (multi-subfield cell). The oscillatory activity of these interneurons is only weakly correlated between neighbouring cells, and in about half of these (44 %) is modulated by depolarizing theta rhythmicity. The overall characteristics of acetylcholine-induced oscillations in slice cultures closely resemble the rhythmicity observed in hippocampal field and single cell recordings in vivo. Both rhythmicities depend on intrinsic synaptic interactions, and are expressed by different cell types. The fact that these oscillations persist in a network lacking extra-hippocampal connections emphasizes the importance of intrinsic mechanisms in determining this form of hippocampal activity.

  11. Mediterranean diet pyramid today. Science and cultural updates.

    Science.gov (United States)

    Bach-Faig, Anna; Berry, Elliot M; Lairon, Denis; Reguant, Joan; Trichopoulou, Antonia; Dernini, Sandro; Medina, F Xavier; Battino, Maurizio; Belahsen, Rekia; Miranda, Gemma; Serra-Majem, Lluís

    2011-12-01

    To present the Mediterranean diet (MD) pyramid: a lifestyle for today. A new graphic representation has been conceived as a simplified main frame to be adapted to the different nutritional and socio-economic contexts of the Mediterranean region. This review gathers updated recommendations considering the lifestyle, dietary, sociocultural, environmental and health challenges that the current Mediterranean populations are facing. Mediterranean region and its populations. Many innovations have arisen since previous graphical representations of the MD. First, the concept of composition of the 'main meals' is introduced to reinforce the plant-based core of the dietary pattern. Second, frugality and moderation is emphasised because of the major public health challenge of obesity. Third, qualitative cultural and lifestyle elements are taken into account, such as conviviality, culinary activities, physical activity and adequate rest, along with proportion and frequency recommendations of food consumption. These innovations are made without omitting other items associated with the production, selection, processing and consumption of foods, such as seasonality, biodiversity, and traditional, local and eco-friendly products. Adopting a healthy lifestyle and preserving cultural elements should be considered in order to acquire all the benefits from the MD and preserve this cultural heritage. Considering the acknowledgment of the MD as an Intangible Cultural Heritage of Humanity by UNESCO (2010), and taking into account its contribution to health and general well-being, we hope to contribute to a much better adherence to this healthy dietary pattern and its way of life with this new graphic representation.

  12. Neonatal Propofol and Etomidate Exposure Enhance Inhibitory Synaptic Transmission in Hippocampal Cornus Ammonis 1 Pyramidal Neurons

    Institute of Scientific and Technical Information of China (English)

    Jia-Qiang Zhang; Wan-Ying Xu; Chang-Qing Xu

    2016-01-01

    Background:Propofol and etomidate are the most important intravenous general anesthetics in the current clinical use and that mediate gamma-aminobutyric acid's (GABAergic) synaptic transmission.However,their long-term effects on GABAergic synaptic transmission induced by neonatal propofol or etomidate exposure remain unclear.We investigated the long-term GABAergic neurotransmission alterations,following neonatal propofol and etomidate administration.Methods:Sprague-Dawley rat pups at postnatal days 4 6 were underwent 6-h-long propofol-induced or 5-h-long etomidate-induced anesthesia.We performed whole-cell patch-clamp recording from pyramidal cells in the cornus ammonis 1 area of acute hippocampal slices of postnatal 80-90 days.Spontaneous and miniature inhibitory GABAergic currents (spontaneous inhibitory postsynaptic currents [sIPSCs] and miniature inhibitory postsynaptic currents [mIPSCs]) and their kinetic characters were measured.The glutamatergic tonic effect on inhibitory transmission and the effect of bumetanide on neonatal propofol exposure were also examined.Results:Neonatal propofol exposure significantly increased the frequency of mIPSCs (from 1.87 ± 0.35 Hz to 3.43 ± 0.51 Hz,P < 0.05) and did not affect the amplitude of mIPSCs and sIPSCs.Both propofol and etomidate slowed the decay time of mIPSCs kinetics (168.39 ± 27.91 ms and 267.02 ± 100.08 ms vs.68.18 ± 12.43 ms;P < 0.05).Bumetanide significantly blocked the frequency increase and reversed the kinetic alteration of mIPSCs induced by neonatal propofol exposure (3.01 ± 0.45 Hz and 94.30 ± 32.56 ms).Conclusions:Neonatal propofol and etomidate exposure has long-term effects on inhibitory GABAergic transmission.Propofol might act at pre-and post-synaptic GABA receptor A (GABAA) receptors within GABAergic synapses and impairs the glutamatergic tonic input to GABAergic synapses;etomidate might act at the postsynaptic site.

  13. Inhibitory nature of tiagabine-augmented GABAA receptor-mediated depolarizing responses in hippocampal pyramidal cells.

    Science.gov (United States)

    Jackson, M F; Esplin, B; Capek, R

    1999-03-01

    Tiagabine is a potent GABA uptake inhibitor with demonstrated anticonvulsant activity. GABA uptake inhibitors are believed to produce their anticonvulsant effects by prolonging the postsynaptic actions of GABA, released during episodes of neuronal hyperexcitability. However, tiagabine has recently been reported to facilitate the depolarizing actions of GABA in the CNS of adult rats following the stimulation of inhibitory pathways at a frequency (100 Hz) intended to mimic interneuronal activation during epileptiform activity. In the present study, we performed extracellular and whole cell recordings from CA1 pyramidal neurons in rat hippocampal slices to examine the functional consequences of tiagabine-augmented GABA-mediated depolarizing responses. Orthodromic population spikes (PSs), elicited from the stratum radiatum, were inhibited following the activation of recurrent inhibitory pathways by antidromic conditioning stimulation of the alveus, which consisted of either a single stimulus or a train of stimuli delivered at high-frequency (100 Hz, 200 ms). The inhibition of orthodromic PSs produced by high-frequency conditioning stimulation (HFS), which was always of much greater strength and duration than that produced by a single conditioning stimulus, was greatly enhanced following the bath application of tiagabine (2-100 microM). Thus, in the presence of tiagabine (20 microM), orthodromic PSs, evoked 200 and 800 ms following HFS, were inhibited to 7.8 +/- 2.6% (mean +/- SE) and 34.4 +/- 18.5% of their unconditioned amplitudes compared with only 35.4 +/- 12.7% and 98.8 +/- 12.4% in control. Whole cell recordings revealed that the bath application of tiagabine (20 microM) either caused the appearance or greatly enhanced the amplitude of GABA-mediated depolarizing responses (DR). Excitatory postsynaptic potentials (EPSPs) evoked from stratum radiatum at time points that coincided with the DR were inhibited to below the threshold for action-potential firing

  14. Downregulation of transient K+ channels in dendrites of hippocampal CA1 pyramidal neurons by activation of PKA and PKC.

    Science.gov (United States)

    Hoffman, D A; Johnston, D

    1998-05-15

    We have reported recently a high density of transient A-type K+ channels located in the distal dendrites of CA1 hippocampal pyramidal neurons and shown that these channels shape EPSPs, limit the back-propagation of action potentials, and prevent dendritic action potential initiation (). Because of the importance of these channels in dendritic signal propagation, their modulation by protein kinases would be of significant interest. We investigated the effects of activators of cAMP-dependent protein kinase (PKA) and the Ca2+-dependent phospholipid-sensitive protein kinase (PKC) on K+ channels in cell-attached patches from the distal dendrites of hippocampal CA1 pyramidal neurons. Inclusion of the membrane-permeant PKA activators 8-bromo-cAMP (8-br-cAMP) or forskolin in the dendritic patch pipette resulted in a depolarizing shift in the activation curve for the transient channels of approximately 15 mV. Activation of PKC by either of two phorbol esters also resulted in a 15 mV depolarizing shift of the activation curve. Neither PKA nor PKC activation affected the sustained or slowly inactivating component of the total outward current. This downregulation of transient K+ channels in the distal dendrites may be responsible for some of the frequently reported increases in cell excitability found after PKA and PKC activation. In support of this hypothesis, we found that activation of either PKA or PKC significantly increased the amplitude of back-propagating action potentials in distal dendrites.

  15. Single mechanically-gated cation channel currents can trigger action potentials in neocortical and hippocampal pyramidal neurons.

    Science.gov (United States)

    Nikolaev, Yury A; Dosen, Peter J; Laver, Derek R; van Helden, Dirk F; Hamill, Owen P

    2015-05-22

    The mammalian brain is a mechanosensitive organ that responds to different mechanical forces ranging from intrinsic forces implicated in brain morphogenesis to extrinsic forces that can cause concussion and traumatic brain injury. However, little is known of the mechanosensors that transduce these forces. In this study we use cell-attached patch recording to measure single mechanically-gated (MG) channel currents and their affects on spike activity in identified neurons in neonatal mouse brain slices. We demonstrate that both neocortical and hippocampal pyramidal neurons express stretch-activated MG cation channels that are activated by suctions of ~25mm Hg, have a single channel conductance for inward current of 50-70pS and show weak selectivity for alkali metal cations (i.e., Na(+)hippocampal pyramidal neurons. Not all neuron types studied here expressed MG channel currents. In particular, locus coeruleus and cerebellar Purkinje neurons showed no detectable MG channel activity. Moreover their robust rhythmic spike activity was resistant to mechanical modulation. Our observation that a single MG channel current can trigger spiking predicates the need for reassessment of the long held view that the impulse output of central neurons depends only upon their intrinsic voltage-gated channels and/or their integrated synaptic input.

  16. The protective role of ascorbic acid on hippocampal CA1 pyramidal neurons in a rat model of maternal lead exposure.

    Science.gov (United States)

    Sepehri, Hamid; Ganji, Farzaneh

    2016-07-01

    Oxidative stress is a major pathogenic mechanism of lead neurotoxicity. The antioxidant ascorbic acid protects hippocampal pyramidal neurons against cell death during congenital lead exposure; however, critical functions like synaptic transmission, integration, and plasticity depend on preservation of dendritic and somal morphology. This study was designed to examine if ascorbic acid also protects neuronal morphology during developmental lead exposure. Timed pregnant rats were divided into four treatment groups: (1) control, (2) 100mg/kg ascorbic acid once a day via gavage, (3) 0.05% lead acetate in drinking water, and (4) 0.05% lead+100mg/kg oral ascorbic acid. Brains of eight male pups (P25) per treatment group were processed for Golgi staining. Changes in hippocampal CA1 pyramidal neurons' somal size were estimated by cross-sectional area and changes in dendritic arborization by Sholl's analysis. One-way ANOVA was used to compare results among treatment groups. Lead-exposed pups exhibited a significant decrease in somal size compared to controls (Pascorbic acid. Sholl's analysis revealed a significant increase in apical dendritic branch points near cell body (PAscorbic acid significantly but only partially reversed the somal and dendritic damage caused by developmental lead exposure. Oxidative stress thus contributes to lead neurotoxicity but other pathogenic mechanisms are also involved.

  17. Proteolytic degradation of glutamate decarboxylase mediates disinhibition of hippocampal CA3 pyramidal cells in cathepsin D-deficient mice.

    Science.gov (United States)

    Shimizu, Tokiko; Hayashi, Yoshinori; Yamasaki, Ryo; Yamada, Jun; Zhang, Jian; Ukai, Kiyoharu; Koike, Masato; Mine, Kazunori; von Figura, Kurt; Peters, Christoph; Saftig, Paul; Fukuda, Takaichi; Uchiyama, Yasuo; Nakanishi, Hiroshi

    2005-08-01

    Although of clinical importance, little is known about the mechanism of seizure in neuronal ceroid lipofuscinosis (NCL). In the present study, we have attempted to elucidate the mechanism underlying the seizure of cathepsin D-deficient (CD-/-) mice that show a novel type of lysosomal storage disease with a phenotype resembling late infantile NCL. In hippocampal slices prepared from CD-/- mice at post-natal day (P)24, spontaneous burst discharges were recorded from CA3 pyramidal cells. At P24, the mean amplitude of IPSPs after stimulation of the mossy fibres was significantly smaller than that of wild-type mice, which was substantiated by the decreased level of gamma-aminobutyric acid (GABA) contents in the hippocampus measured by high-performance liquid chromatography (HPLC). At this stage, activated microglia were found to accumulate in the pyramidal cell layer of the hippocampal CA3 subfield of CD-/- mice. However, there was no significant change in the numerical density of GABAergic interneurons in the CA3 subfield of CD-/- mice at P24, estimated by counting the number of glutamate decarboxylase (GAD) 67-immunoreactive somata. In the hippocampus and the cortex of CD-/- mice at P24, some GABAergic interneurons displayed extremely high somatic granular immunoreactivites for GAD67, suggesting the lysosomal accumulation of GAD67. GAD67 levels in axon terminals abutting on to perisomatic regions of hippocampal CA3 pyramidal cells was not significantly changed in CD-/- mice even at P24, whereas the total protein levels of GAD67 in both the hippocampus and the cortex of CD-/- mice after P24 were significantly decreased as a result of degradation. Furthermore, the recombinant human GAD65/67 was rapidly digested by the lysosomal fraction prepared from the whole brain of wild-type and CD-/- mice. These observations strongly suggest that the reduction of GABA contents, presumably because of lysosomal degradation of GAD67 and lysosomal accumulation of its degraded forms

  18. Kv4 potassium channel subunits control action potential repolarization and frequency-dependent broadening in rat hippocampal CA1 pyramidal neurones.

    Science.gov (United States)

    Kim, Jinhyun; Wei, Dong-Sheng; Hoffman, Dax A

    2005-11-15

    A-type potassium channels regulate neuronal firing frequency and the back-propagation of action potentials (APs) into dendrites of hippocampal CA1 pyramidal neurones. Recent molecular cloning studies have found several families of voltage-gated K(+) channel genes expressed in the mammalian brain. At present, information regarding the relationship between the protein products of these genes and the various neuronal functions performed by voltage-gated K(+) channels is lacking. Here we used a combination of molecular, electrophysiological and imaging techniques to show that one such gene, Kv4.2, controls AP half-width, frequency-dependent AP broadening and dendritic action potential propagation. Using a modified Sindbis virus, we expressed either the enhanced green fluorescence protein (EGFP)-tagged Kv4.2 or an EGFP-tagged dominant negative mutant of Kv4.2 (Kv4.2g(W362F)) in CA1 pyramidal neurones of organotypic slice cultures. Neurones expressing Kv4.2g(W362F) displayed broader action potentials with an increase in frequency-dependent AP broadening during a train compared with control neurones. In addition, Ca(2)(+) imaging of Kv4.2g(W362F) expressing dendrites revealed enhanced AP back-propagation compared to control neurones. Conversely, neurones expressing an increased A-type current through overexpression of Kv4.2 displayed narrower APs with less frequency dependent broadening and decreased dendritic propagation. These results point to Kv4.2 as the major contributor to the A-current in hippocampal CA1 neurones and suggest a prominent role for Kv4.2 in regulating AP shape and dendritic signalling. As Ca(2)(+) influx occurs primarily during AP repolarization, Kv4.2 activity can regulate cellular processes involving Ca(2)(+)-dependent second messenger cascades such as gene expression and synaptic plasticity.

  19. Blockade of Ca2+-permeable AMPA/kainate channels decreases oxygen-glucose deprivation-induced Zn2+ accumulation and neuronal loss in hippocampal pyramidal neurons.

    Science.gov (United States)

    Yin, Hong Z; Sensi, Stefano L; Ogoshi, Fumio; Weiss, John H

    2002-02-15

    Synaptic release of Zn2+ and its translocation into postsynaptic neurons probably contribute to neuronal injury after ischemia or epilepsy. Studies in cultured neurons have revealed that of the three major routes of divalent cation entry, NMDA channels, voltage-sensitive Ca2+ channels (VSCCs), and Ca2+-permeable AMPA/kainate (Ca-A/K) channels, Ca-A/K channels exhibit the highest permeability to exogenously applied Zn2+. However, routes through which synaptically released Zn2+ gains entry to postsynaptic neurons have not been characterized in vivo. To model ischemia-induced Zn2+ movement in a system approximating the in vivo situation, we subjected mouse hippocampal slice preparations to controlled periods of oxygen and glucose deprivation (OGD). Timm's staining revealed little reactive Zn2+ in CA1 and CA3 pyramidal neurons of slices exposed in the presence of O2 and glucose. However, 15 min of OGD resulted in marked labeling in both regions. Whereas strong Zn2+ labeling persisted if both the NMDA antagonist MK-801 and the VSCC blocker Gd3+ were present during OGD, the presence of either the Ca-A/K channel blocker 1-naphthyl acetyl spermine (NAS) or the extracellular Zn2+ chelator Ca2+ EDTA substantially decreased Zn2+ accumulation in pyramidal neurons of both subregions. In parallel experiments, slices were subjected to 5 min OGD exposures as described above, followed 4 hr later by staining with the cell-death marker propidium iodide. As in the Timm's staining experiments, substantial CA1 or CA3 pyramidal neuronal damage occurred despite the presence of MK-801 and Gd3+, whereas injury was decreased by NAS or by Ca2+ EDTA (in CA1).

  20. Activation of functional α7-containing nAChRs in hippocampal CA1 pyramidal neurons by physiological levels of choline in the presence of PNU-120596.

    Directory of Open Access Journals (Sweden)

    Bopanna I Kalappa

    Full Text Available BACKGROUND: The level of expression of functional α7-containing nicotinic acetylcholine receptors (nAChRs in hippocampal CA1 pyramidal neurons is believed to be very low compared to hippocampal CA1 interneurons, and for many years this expression was largely overlooked. However, high densities of expression of functional α7-containing nAChRs in CA1 pyramidal neurons may not be necessary for triggering important cellular and network functions, especially if activation of α7-containing nAChRs occurs in the presence of positive allosteric modulators such as PNU-120596. METHODOLOGY/PRINCIPAL FINDINGS: An approach previously developed for α7-containing nAChRs expressed in tuberomammillary neurons was applied to investigate functional CA1 pyramidal α7-containing nAChRs using rat coronal hippocampal slices and patch-clamp electrophysiology. The majority (∼71% of tested CA1 pyramidal neurons expressed low densities of functional α7-containing nAChRs as evidenced by small whole-cell responses to choline, a selective endogenous agonist of α7 nAChRs. These responses were potentiated by PNU-120596, a novel positive allosteric modulator of α7 nAChRs. The density of functional α7-containing nAChRs expressed in CA1 pyramidal neurons (and thus, the normalized net effect of activation, i.e., response net charge per unit of membrane capacitance per unit of time was estimated to be ∼5% of the density observed in CA1 interneurons. The results of this study demonstrate that despite low levels of expression of functional pyramidal α7-containing nAChRs, physiological levels of choline (∼10 µM are sufficient to activate these receptors and transiently depolarize and even excite CA1 pyramidal neurons in the presence of PNU-120596. The observed effects are possible because in the presence of 10 µM choline and 1-5 µM PNU-120596, a single opening of an individual pyramidal α7-containing nAChR ion channel appears to transiently depolarize (∼4 mV the

  1. The electrical activity of hippocampal pyramidal neuron is subjected to descending control by the brain orexin/hypocretin system.

    Science.gov (United States)

    Riahi, Esmail; Arezoomandan, Reza; Fatahi, Zahra; Haghparast, Abbas

    2015-03-01

    The hippocampus receives sparse orexinergic innervation from the lateral hypothalamus and expresses a high level of orexin receptor. The function of orexin receptor in the regulation of hippocampal neural activity has never been investigated. In this study, in vivo single unit recording was performed in urethane-anesthetized rats. After 15 min of baseline recording from pyramidal neuron within the CA1 region of the dorsal hippocampus, i.c.v. injection of orexin-A 0.5 nmol, SB334867 400 nmol, a selective orexin receptor 1 antagonist, saline, or DMSO, or microinjection of carbachol 250 nmol or saline into the ipsilateral lateral hypothalamus were performed using a Hamilton microsyringe, and the spontaneous firing activity continued to be recorded for 25 min. Results showed that orexin administration into the lateral cerebral ventricle excited 6 out of 8 neurons and inhibited 1 neuron. Chemical stimulation of the lateral hypothalamus by carbachol excited 9 out of 13 hippocampal neurons and inhibited 3 neurons. On the other hand, i.c.v. injection of the SB334867, caused reductions in the firing activity of 6 out of 10 neurons and increases in 4 additional neurons. It seems that orexin neurotransmission in the hippocampus mostly elicits an excitatory response, whereas blockade of orexin receptor has an inhibitory effect. Further studies need to be done to elucidate the underlying mechanism of orexin action on hippocampal neurons.

  2. Action potential repolarization and a fast after-hyperpolarization in rat hippocampal pyramidal cells.

    Science.gov (United States)

    Storm, J F

    1987-04-01

    1. The repolarization of the action potential, and a fast after-hyperpolarization (a.h.p.) were studied in CA1 pyramidal cells (n = 76) in rat hippocampal slices (28-37 degrees C). Single spikes were elicited by brief (1-3 ms) current pulses, at membrane potentials close to rest (-60 to -70 mV). 2. Each action potential was followed by four after-potentials: (a) the fast a.h.p., lasting 2-5 ms; (b) an after-depolarization; (c) a medium a.h.p., (50-100 ms); and (d) a slow a.h.p. (1-2 s). Both the fast a.h.p. and the slow a.h.p. (but not the medium a.h.p.) were inhibited by Ca2+-free medium or Ca2+-channel blockers (Co2+, Mn2+ or Cd2+); but tetraethylammonium (TEA; 0.5-2 nM) blocked only the fast a.h.p., and noradrenaline (2-5 microM) only the slow a.h.p. This suggests that two Ca2+-activated K+ currents were involved: a fast, TEA-sensitive one (IC) underlying the fast a.h.p., and a slow noradrenaline-sensitive one (IAHP) underlying the slow a.h.p. 3. Like the fast a.h.p., spike repolarization seems to depend on a Ca2+-dependent K+ current of the fast, TEA-sensitive kind (IC). The repolarization was slowed by Ca2+-free medium, Co2+, Mn2+, Cd2+, or TEA, but not by noradrenaline. Charybdotoxin (CTX; 30 nM), a scorpion toxin which blocks the large-conductance Ca2+-activated K+ channel in muscle, had a similar effect to TEA. The effects of TEA and Cd2+ (or Mn2+) showed mutual occlusion. Raising the external K+ concentration reduced the fast a.h.p. and slowed the spike repolarization, whereas Cl- loading of the cell was ineffective. 4. The transient K+ current, IA, seems also to contribute to spike repolarization, because: (a) 4-aminopyridine (4-AP; 0.1 mM), which blocks IA, slowed the spike repolarization; (b) depolarizing pre-pulses, which inactivate IA, had a similar effect; (c) hyperpolarizing pre-pulses speeded up the spike repolarization; (d) the effects of 4-AP and pre-pulses persisted during Ca2+ blockade (like IA); and (e) depolarizing pre-pulses reduced the

  3. Localized gene transfer into organotypic hippocampal slice cultures and acute hippocampal slices

    DEFF Research Database (Denmark)

    Casaccia-Bonnefil, P; Benedikz, Eirikur; Shen, H;

    1993-01-01

    Viral vectors derived from herpes simplex virus, type-1 (HSV), can transfer and express genes into fully differentiated, post-mitotic neurons. These vectors also transduce cells effectively in organotypic hippocampal slice cultures. Nanoliter quantities of a virus stock of HSVlac, an HSV vector...... or hippocampal slices. The rapid expression of beta-gal by HSVlac allowed efficient transduction of acute hippocampal slices. Many genes have been transduced and expressed using HSV vectors; therefore, this microapplication method can be applied to many neurobiological questions....

  4. Delayed effects of corticosterone on slow after-hyperpolarization potentials in mouse hippocampal versus prefrontal cortical pyramidal neurons.

    Directory of Open Access Journals (Sweden)

    Anup G Pillai

    Full Text Available The rodent stress hormone corticosterone changes neuronal activity in a slow and persistent manner through transcriptional regulation. In the rat dorsal hippocampus, corticosterone enhances the amplitude of calcium-dependent potassium currents that cause a lingering slow after-hyperpolarization (sAHP at the end of depolarizing events. In this study we compared the putative region-dependency of the delayed effects of corticosterone (approximately 5 hrs after treatment on sAHP as well as other active and passive properties of layer 2/3 pyramidal neurons from three prefrontal areas, i.e. the lateral orbitofrontal, prelimbic and infralimbic cortex, with the hippocampus of adult mice. In agreement with previous studies, corticosterone increased sAHP amplitude in the dorsal hippocampus with depolarizing steps of increasing amplitude. However, in the lateral orbitofrontal, prelimbic and infralimbic cortices we did not observe any modifications of sAHP amplitude after corticosterone treatment. Properties of single action potentials or % ratio of the last spike interval with respect to the first spike interval, an indicator of accommodation in an action potential train, were not significantly affected by corticosterone in all brain regions examined. Lastly, corticosterone treatment did not induce any lasting changes in passive membrane properties of hippocampal or cortical neurons. Overall, the data indicate that corticosterone slowly and very persistently increases the sAHP amplitude in hippocampal pyramidal neurons, while this is not the case in the cortical regions examined. This implies that changes in excitability across brain regions reached by corticosterone may vary over a prolonged period of time after stress.

  5. Tonic GABAA conductance decreases membrane time constant and increases EPSP-spike precision in hippocampal pyramidal neurons

    Directory of Open Access Journals (Sweden)

    Agnieszka I Wlodarczyk

    2013-12-01

    Full Text Available Because of a complex dendritic structure, pyramidal neurons have a large membrane surface relative to other cells and so a large electrical capacitance and a large membrane time constant (τm. This results in slow depolarizations in response to excitatory synaptic inputs, and consequently increased and variable action potential latencies, which may be computationally undesirable. Tonic activation of GABAA receptors increases membrane conductance and thus regulates neuronal excitability by shunting inhibition. In addition, tonic increases in membrane conductance decrease the membrane time constant (τm, and improve the temporal fidelity of neuronal firing. Here we performed whole-cell current clamp recordings from hippocampal CA1 pyramidal neurons and found that bath application of 10 µM GABA indeed decreases τm in these cells. GABA also decreased first spike latency and jitter (standard deviation of the latency produced by current injection of 2 rheobases (500 ms. However, when larger current injections (3-6 rheobases were used, GABA produced no significant effect on spike jitter, which was low. Using mathematical modelling we demonstrate that the tonic GABAA conductance decreases rise time, decay time and half-width of EPSPs in pyramidal neurons. A similar effect was observed on EPSP/IPSP pairs produced by stimulation of Schaffer collaterals: the EPSP part of the response became shorter after application of GABA. Consistent with the current injection data, a significant decrease in spike latency and jitter was obtained in cell attached recordings only at near-threshold stimulation (50% success rate, S50. When stimulation was increased to 2- or 3- times S50, GABA significantly affected neither spike latency nor spike jitter. Our results suggest that a decrease in τm associated with elevations in ambient GABA can improve EPSP-spike precision at near-threshold synaptic inputs.

  6. Tonic GABAA conductance decreases membrane time constant and increases EPSP-spike precision in hippocampal pyramidal neurons.

    Science.gov (United States)

    Wlodarczyk, Agnieszka I; Xu, Chun; Song, Inseon; Doronin, Maxim; Wu, Yu-Wei; Walker, Matthew C; Semyanov, Alexey

    2013-01-01

    Because of a complex dendritic structure, pyramidal neurons have a large membrane surface relative to other cells and so a large electrical capacitance and a large membrane time constant (τm). This results in slow depolarizations in response to excitatory synaptic inputs, and consequently increased and variable action potential latencies, which may be computationally undesirable. Tonic activation of GABAA receptors increases membrane conductance and thus regulates neuronal excitability by shunting inhibition. In addition, tonic increases in membrane conductance decrease the membrane time constant (τm), and improve the temporal fidelity of neuronal firing. Here we performed whole-cell current clamp recordings from hippocampal CA1 pyramidal neurons and found that bath application of 10μM GABA indeed decreases τm in these cells. GABA also decreased first spike latency and jitter (standard deviation of the latency) produced by current injection of 2 rheobases (500 ms). However, when larger current injections (3-6 rheobases) were used, GABA produced no significant effect on spike jitter, which was low. Using mathematical modeling we demonstrate that the tonic GABAA conductance decreases rise time, decay time and half-width of EPSPs in pyramidal neurons. A similar effect was observed on EPSP/IPSP pairs produced by stimulation of Schaffer collaterals: the EPSP part of the response became shorter after application of GABA. Consistent with the current injection data, a significant decrease in spike latency and jitter was obtained in cell attached recordings only at near-threshold stimulation (50% success rate, S50). When stimulation was increased to 2- or 3- times S50, GABA significantly affected neither spike latency nor spike jitter. Our results suggest that a decrease in τm associated with elevations in ambient GABA can improve EPSP-spike precision at near-threshold synaptic inputs.

  7. Homeostatic maintenance in excitability of tree shrew hippocampal CA3 pyramidal neurons after chronic stress

    NARCIS (Netherlands)

    Kole, MHP; Czeh, B; Fuchs, E

    2004-01-01

    The experience of chronic stress induces a reversible regression of hippocampal CA3 apical neuron dendrites. Although such postsynaptic membrane reduction will obviously diminish the possibility of synaptic input, the consequences for the functional membrane properties of these cells are not well un

  8. Convergence of entorhinal and CA3 inputs onto pyramidal neurons and interneurons in hippocampal area CA1--an anatomical study in the rat.

    Science.gov (United States)

    Kajiwara, Riichi; Wouterlood, Floris G; Sah, Anupam; Boekel, Amber J; Baks-te Bulte, Luciënne T G; Witter, Menno P

    2008-01-01

    The entorhinal cortex (EC) conveys information to hippocampal field CA1 either directly by way of projections from principal neurons in layer III, or indirectly by axons from layer II via the dentate gyrus, CA3, and Schaffer collaterals. These two pathways differentially influence activity in CA1, yet conclusive evidence is lacking whether and to what extent they converge onto single CA1 neurons. Presently we studied such convergence. Different neuroanatomical tracers injected into layer III of EC and into CA3, respectively, tagged simultaneously the direct entorhino-hippocampal fibers and the indirect innervation of CA1 neurons by Schaffer collaterals. In slices of fixed brains we intracellularly filled CA1 pyramidal cells and interneurons in stratum lacunosum-moleculare (LM) and stratum radiatum (SR). Sections of these slices were scanned in a confocal laser scanning microscope. 3D-reconstruction was used to determine whether boutons of the labeled input fibers were in contact with the intracellularly filled neurons. We analyzed 12 pyramidal neurons and 21 interneurons. Perforant path innervation to pyramidal neurons in our material was observed to be denser than that from CA3. All pyramidal neurons and 17 of the interneurons received contacts of both perforant pathway and Schaffer input on their dendrites and cell bodies. Four interneurons, which were completely embedded in LM, received only labeled perforant pathway input. Thus, we found convergence of both projection systems on single CA1 pyramidal and interneurons with dendrites that access the layers where perforant pathway fibers and Schaffer collaterals end.

  9. Penicillin-induced epileptogenesis in immature rat CA3 hippocampal pyramidal cells.

    Science.gov (United States)

    Swann, J W; Brady, R J

    1984-02-01

    Penicillin's ability to produce epileptiform discharges in the CA3 region of hippocampus was examined both extracellularly and intracellularly in slices taken from immature rats 3-25 days of age. Comparisons were made to similar recordings from slices taken from mature rats. Between postnatal days 9 and 19 penicillin treatment resulted in spontaneous extracellular epileptiform bursts and coincident intracellular depolarization shifts. These events were more prolonged and less frequent than in slices from mature rats, and the bursts were followed by prolonged afterdischarges, often 20-30 s in duration. Intracellularly these afterdischarges consisted of large, rhythmic slow depolarizing potentials, which resulted in one or more action potentials in individual CA3 pyramidal cells. Extracellular field recordings showed these events to be simultaneous with synchronous discharges of a large population of CA3 pyramidal cells. In pups 1-2 weeks of age the ability of hippocampus to produce prolonged afterdischarges was associated with a slow depolarizing afterpotential, which followed the downstroke of the depolarization shift. Coincident with this afterpotential was a prolonged negative field in the CA3 pyramidal cell body layer. By postnatal days 24 and 25 the tendency to generate afterdischarges was greatly reduced. In addition, afterdischarges were observed infrequently in slices taken during the first postnatal week. Spike trains produced by prolonged intracellular current injection in slices taken on postnatal days 9-19 were followed by large afterhyperpolarizations and were unable to produce afterdischarges in individual CA3 pyramidal cells. Intracellular recordings from presumed glial cells suggest that extracellular K+ accumulation may play a role in the pronounced capacity of hippocampus from 1- and 2-week-old rat pups to generate prolonged afterdischarges.

  10. Excitatory synaptic activity is associated with a rapid structural plasticity of inhibitory synapses on hippocampal CA1 pyramidal cells

    OpenAIRE

    Lushnikova, Irina; Skibo, Galina; Muller, Dominique; Nikonenko, Iryna

    2011-01-01

    Synaptic activity, such as long-term potentiation (LTP), has been shown to induce morphological plasticity of excitatory synapses on dendritic spines through the spine head and postsynaptic density (PSD) enlargement and reorganization. Much less, however, is known about activity-induced morphological modifications of inhibitory synapses. Using an in vitro model of rat organotypic hippocampal slice cultures and electron microscopy, we studied activity-related morphological changes of somatic i...

  11. Cholinergic modulation differs between basal and apical dendritic excitation of hippocampal CA1 pyramidal cells.

    Science.gov (United States)

    Leung, L Stan; Péloquin, Pascal

    2010-08-01

    We hypothesize that endogenous cholinergic modulation of dendritic processing of hippocampal CA1 is layer specific, and it specifically enhances spike output resulting from basal as compared with the apical dendritic excitation. Laminar profiles of evoked field potentials were recorded in the CA1 area of urethane-anesthetized rats using multichannel silicon probes and analyzed as current source density. High-frequency stimulation of the pontis oralis (PnO) attenuated the midapical more than the basal or distal apical dendritic excitatory sink. Population spike (PS) and excitatory sink-PS potentiation resulting from basal dendritic excitation were facilitated, while the PS evoked by apical dendritic stimulation was attenuated by PnO stimulation. Perfusion of cholinergic agonist carbachol onto hippocampal slices in vitro also attenuated the apical more than the basal dendritic excitatory postsynaptic potentials. Excitatory sink attenuation and PS changes after PnO stimulation were blocked by systemic or local scopolamine and by intracerebroventricular (icv) M1 receptor antagonist pirenzepine but not by icv M2 receptor antagonist AFDX-116 or nicotinic antagonists. However, a hippocampal theta rhythm activated by PnO stimulation was blocked by systemic but not by local scopolamine. We conclude that endogenous acetylcholine mediates a stronger presynaptic inhibition of the midapical than basal and distal apical excitation mainly through M1 receptors.

  12. Low Concentrations of Alcohol Inhibit BDNF-Dependent GABAergic Plasticity via L-type Ca2+ channel Inhibition in Developing CA3 Hippocampal Pyramidal Neurons

    OpenAIRE

    Zucca, Stefano; Valenzuela, C. Fernando

    2010-01-01

    Fetal Alcohol Spectrum Disorder (FASD) is associated with learning and memory alterations that could be, in part, a consequence of hippocampal damage. The CA3 hippocampal subfield is one of the regions affected by ethanol (EtOH), including exposure during the 3rd trimester-equivalent (i.e. neonatal period in rats). However, the mechanism of action of EtOH is poorly understood. In CA3 pyramidal neurons from neonatal rats, dendritic BDNF release causes long-term potentiation of the frequency of...

  13. 5-Hydroxytryptamine1A receptor-activation hyperpolarizes pyramidal cells and suppresses hippocampal gamma oscillations via Kir3 channel activation.

    Science.gov (United States)

    Johnston, April; McBain, Chris J; Fisahn, André

    2014-10-01

    Rhythmic cortical neuronal oscillations in the gamma frequency band (30-80 Hz, gamma oscillations) have been associated with cognitive processes such as sensory perception and integration, attention, learning, and memory. Gamma oscillations are disrupted in disorders for which cognitive deficits are hallmark symptoms such as schizophrenia and Alzheimer's disease.In vitro, various neurotransmitters have been found to modulate gamma oscillations. Serotonin(5-HT) has long been known to be important for both behavioural and cognitive functions such as learning and memory. Multiple 5-HT receptor subtypes are expressed in the CA3 region of the hippocampus and high doses of 5-HT reduce the power of induced gamma oscillations.Hypothesizing that 5-HT may have cell- and receptor subtype-specific modulatory effects, we investigated the receptor subtypes, cell types and cellular mechanisms engaged by 5-HT in the modulation of gamma oscillations in mice and rats. We found that 5-HT decreases the power of kainate-induced hippocampal gamma oscillations in both species via the 5-HT1A receptor subtype. Whole-cell patch clamp recordings demonstrated that this decrease was caused by a hyperpolarization of CA3 pyramidal cells and a reduction of their firing frequency, but not by alteration of inhibitory neurotransmission. Finally, our results show that the effect on pyramidal cells is mediated via the G protein-coupled receptor inwardly rectifying potassium channel Kir3.Our findings suggest this novel cellular mechanism as a potential target for therapies that are aimed at alleviating cognitive decline by helping the brain to maintain or re-establish normal gamma oscillation levels in neuropsychiatric and neurodegenerative disorders.

  14. Calcium-activated potassium conductances contribute to action potential repolarization at the soma but not the dendrites of hippocampal CA1 pyramidal neurons.

    Science.gov (United States)

    Poolos, N P; Johnston, D

    1999-07-01

    Evidence is accumulating that voltage-gated channels are distributed nonuniformly throughout neurons and that this nonuniformity underlies regional differences in excitability within the single neuron. Previous reports have shown that Ca2+, Na+, A-type K+, and hyperpolarization-activated, mixed cation conductances have varying distributions in hippocampal CA1 pyramidal neurons, with significantly different densities in the apical dendrites compared with the soma. Another important channel mediates the large-conductance Ca2+-activated K+ current (IC), which is responsible in part for repolarization of the action potential (AP) and generation of the afterhyperpolarization that follows the AP recorded at the soma. We have investigated whether this current is activated by APs retrogradely propagating in the dendrites of hippocampal pyramidal neurons using whole-cell dendritic patch-clamp recording techniques. We found no IC activation by back-propagating APs in distal dendritic recordings. Dendritic APs activated IC only in the proximal dendrites, and this activation decayed within the first 100-150 micrometer of distance from the soma. The decay of IC in the proximal dendrites occurred despite AP amplitude, plus presumably AP-induced Ca2+ influx, that was comparable with that at the soma. Thus we conclude that IC activation by action potentials is nonuniform in the hippocampal pyramidal neuron, which may represent a further example of regional differences in neuronal excitability that are determined by the nonuniform distribution of voltage-gated channels in dendrites.

  15. Hippocampal network dynamics constrain the time lag between pyramidal cells across modified environments

    Science.gov (United States)

    Diba, Kamran; Buzsáki, György

    2008-01-01

    The hippocampus provides a spatial map of the environment. Changes in the environment alter the firing patterns of hippocampal neurons, but are presumably constrained by elements of the network dynamics. We compared the neural activity in CA1 and CA3 regions of the hippocampus in rats running for water reward on a linear track, before and after the track length was shortened. A fraction of cells lost their place-fields and new sets of cells with fields emerged, indicating distinct representation of the two tracks. Cells active in both environments shifted their place-fields in a location dependent manner, most notably at the beginning and the end of the track. Furthermore, peak firing rates and place-field sizes decreased, while place-field overlap and co-activity increased. Power in the theta-frequency band of the local field potentials also decreased in both CA1 and CA3, along with the coherence between the two structures. In contrast, the theta-scale (0–150 ms) time lags between cell pairs, representing distances on the tracks, were conserved, and the activity of the inhibitory neuron population was maintained across environments. We interpret these observations as reflecting the freedoms and constraints of the hippocampal network dynamics. The freedoms permit the necessary flexibility for the network to distinctly represent unique patterns, while the dynamics constrain the speed at which activity propagates between the cell assemblies representing the patterns. PMID:19074018

  16. VIP enhances both pre- and postsynaptic GABAergic transmission to hippocampal interneurones leading to increased excitatory synaptic transmission to CA1 pyramidal cells.

    Science.gov (United States)

    Cunha-Reis, Diana; Sebastião, Ana M; Wirkner, Kerstin; Illes, Peter; Ribeiro, Joaquim Alexandre

    2004-11-01

    Vasoactive intestinal peptide (VIP) is present in the hippocampus in three subtypes of GABAergic interneurones, two of which innervate preferentially other interneurones, responsible for pyramidal cell inhibition. We investigated how pre- and postsynaptic modulation of GABAergic transmission (to both pyramidal cells and interneurones) by VIP could influence excitatory synaptic transmission in the CA1 area of the hippocampus. VIP (0.1-100 nM) increased [(3)H]GABA release from hippocampal synaptosomes (maximum effect at 1 nM VIP; 63.8 +/- 4.0%) but did not change [(3)H]glutamate release. VIP (0.3-30 nM) enhanced synaptic transmission in hippocampal slices (maximum effect at 1 nM VIP; field excitatory postsynaptic potentials (epsp) slope: 23.7 +/- 1.1%; population spike amplitude: 20.3 +/- 1.7%). The action on field epsp slope was fully dependent on GABAergic transmission since it was absent in the presence of picrotoxin (50 microM) plus CGP55845 (1 microM). VIP (1 nM) did not change paired-pulse facilitation but increased paired-pulse inhibition in CA1 pyramidal cells (16.0 +/- 0.9%), reinforcing the involvement of GABAergic transmission in the action of VIP. VIP (1 nM) increased muscimol-evoked inhibitory currents by 36.4 +/- 8.7% in eight out of ten CA1 interneurones in the stratum radiatum. This suggests that VIP promotes increased inhibition of interneurones that control pyramidal cells, leading to disinhibition of synaptic transmission to pyramidal cell dendrites. In conclusion, concerted pre- and postsynaptic actions of VIP lead to disinhibition of pyramidal cell dendrites causing an enhancement of synaptic transmission.

  17. Agmatine increases proliferation of cultured hippocampal progenitor cells and hippocampal neurogenesis in chronically stressed mice

    Institute of Scientific and Technical Information of China (English)

    Yun-feng LI; Hong-xia CHEN; Ying LIU; You-zhi ZHANG; Yan-qin LIU; Jin LI

    2006-01-01

    Aim:To explore the mechanism of agmatine's antidepressant action.Methods: Male mice were subjected to a variety of unpredictable stressors on a daily basis over a 24-d period.The open-field behaviors of the mice were displayed and recorded using a Videomex-V image analytic system automatically.For bromodeoxyuridine (BrdU;thymidine analog as a marker for dividing cells) labeling,the mice were injected with BrdU (100 mg/kg,ip,twice per d for 2 d),and the hippocampal neurogenesis in stressed mice was measured by immunohistochemistry.The proliferation of cultured hippocampal progenitor cells from neonatal rats was determined by colorimetric assay (cell counting kit-8) and 3H-thymidine incorporation assay.Results:After the onset of chronic stress,the locomotor activity of the mice in the open field significantly decreased,while coadministration of agmatine 10 mg/kg (po) blocked it.Furthermore,the number of BrdU-labeled cells in the hippocampal dentate gyrus significantly decreased in chronically stressed mice, which was also blocked by chronic coadministration with agmatine 10 mg/kg (po). Four weeks after the BrdU injection, some of the new born cells matured and became neurons, as determined by double labeling for BrdU and neuron specific enolase (NSE), a marker for mature neurons.In vitro treatment with agmatine 0.1-10 μmo1/L for 3 d significantly increased the proliferation of the cultured hippocampal progenitor cells in a dose-dependent manner.Conclusion:We have found that agmatine increases proliferation of hippocampal progenitor cells in vitro and the hippocampal neurogenesis in vivo in chronically stressed mice.This may be one of the important mechanisms involved in agmatine's antidepressant action.

  18. Biphasic somatic A-type K channel downregulation mediates intrinsic plasticity in hippocampal CA1 pyramidal neurons.

    Directory of Open Access Journals (Sweden)

    Sung-Cherl Jung

    Full Text Available Since its original description, the induction of synaptic long-term potentiation (LTP has been known to be accompanied by a lasting increase in the intrinsic excitability (intrinsic plasticity of hippocampal neurons. Recent evidence shows that dendritic excitability can be enhanced by an activity-dependent decrease in the activity of A-type K(+ channels. In the present manuscript, we examined the role of A-type K(+ channels in regulating intrinsic excitability of CA1 pyramidal neurons of the hippocampus after synapse-specific LTP induction. In electrophysiological recordings we found that LTP induced a potentiation of excitability which was accompanied by a two-phased change in A-type K(+ channel activity recorded in nucleated patches from organotypic slices of rat hippocampus. Induction of LTP resulted in an immediate but short lasting hyperpolarization of the voltage-dependence of steady-state A-type K(+ channel inactivation along with a progressive, long-lasting decrease in peak A-current density. Blocking clathrin-mediated endocytosis prevented the A-current decrease and most measures of intrinsic plasticity. These results suggest that two temporally distinct but overlapping mechanisms of A-channel downregulation together contribute to the plasticity of intrinsic excitability. Finally we show that intrinsic plasticity resulted in a global enhancement of EPSP-spike coupling.

  19. [PI 3 K/Akt signaling pathway contributed to the protective effect of acupuncture intervention on epileptic seizure-induced injury of hippocampal pyramidal cells in epilepsy rats].

    Science.gov (United States)

    Yang, Fan; Ang, Wen-Ping; Shen, De-Kai; Liu, Xiang-Guo; Yang, Yong-Qing; Ma, Yun

    2013-02-01

    To observe the protective effect of acupuncture stimulation on pyramidal cells in hippocampal CA 1 and CA 3 regions and to analyze the involvement of phosphatidy linositol-3-kinase (PI 3 K)/protein kinase B(PKB or Akt) signaling pathway in the acupuncture effect in epilepsy rats. A total of 120 SD rats were randomly divided into normal control group, model group, LY 294002 (a specific antagonist for PI 3 K/Akt signaling) group, acupuncture+ LY 294002 group and acupuncture group (n = 24 in each group, 12 for H. E. staining, and 12 for electron microscope observation). Epilepsy model was established by intraperitoneal injection of pentylenetetrazol (PTZ, 5 microL). Manual acupuncture stimulation was applied to "Baihui" (GV 20) and "Dazhui" (GV 14) once daily for 5 days. Dimethyl Sulfoxide (DMSO, 5 microL, a control solvent) was given to rats of the normal, model and acupuncture groups, and LY294002 (5 microL, dissolved in DMSO) given to rats of the LY 294002 and acupuncture+ LY 294002 groups by lateral ventricular injection. Four hours and 24 h after modeling, the hippocampus tissues were sampled for observing pathological changes of CA 1 and CA 3 regions after H. E. staining under light microscope and for checkin ultrastructural changes of the pyramidal cells under transmission electron microscope. In comparison with the normal control group, the numbers of pyramidal cells of hippocampal CA 3 region in the model group were decreased significantly 4 h and 24 h after epileptic seizure (P acupuncture group were increased considerably in the number at both 4 h and 24 h after seizure (P acupuncture+ LY 294002 and model groups in the numbers of pyramidal cells at 4 h and 24 h after seizure (P > 0.05). Findings of the light microscope and electron microscope showed that the injury severity of pyramidal cells of hippocampal CA 1 and CA 3 regions was moderate 4 h after epileptic seizure and even worse 24 h after seizure in the model group, LY 294002 group and acupuncture+ LY

  20. Diversity of neuropsin (KLK8)-dependent synaptic associativity in the hippocampal pyramidal neuron.

    Science.gov (United States)

    Ishikawa, Yasuyuki; Tamura, Hideki; Shiosaka, Sadao

    2011-07-15

    Hippocampal early (E-) long-term potentiation (LTP) and long-term depression (LTD) elicited by a weak stimulus normally fades within 90 min. Late (L-) LTP and LTD elicited by strong stimuli continue for >180 min and require new protein synthesis to persist. If a strong tetanus is applied once to synaptic inputs, even a weak tetanus applied to another synaptic input can evoke persistent LTP. A synaptic tag is hypothesized to enable the capture of newly synthesized synaptic molecules. This process, referred to as synaptic tagging, is found between not only the same processes (i.e. E- and L-LTP; E- and L-LTD) but also between different processes (i.e. E-LTP and L-LTD; E-LTD and L-LTP) induced at two independent synaptic inputs (cross-tagging). However, the mechanisms of synaptic tag setting remain unclear. In our previous study, we found that synaptic associativity in the hippocampal Schaffer collateral pathway depended on neuropsin (kallikrein-related peptidase 8 or KLK8), a plasticity-related extracellular protease. In the present study, we investigated how neuropsin participates in synaptic tagging and cross-tagging. We report that neuropsin is involved in synaptic tagging during LTP at basal and apical dendritic inputs. Moreover, neuropsin is involved in synaptic tagging and cross-tagging during LTP at apical dendritic inputs via integrin β1 and calcium/calmodulin-dependent protein kinase II signalling. Thus, neuropsin is a candidate molecule for the LTP-specific tag setting and regulates the transformation of E- to L-LTP during both synaptic tagging and cross-tagging.

  1. Plasticity-dependent, full detonation at hippocampal mossy fiber–CA3 pyramidal neuron synapses

    Science.gov (United States)

    Vyleta, Nicholas P; Borges-Merjane, Carolina; Jonas, Peter

    2016-01-01

    Mossy fiber synapses on CA3 pyramidal cells are 'conditional detonators' that reliably discharge postsynaptic targets. The 'conditional' nature implies that burst activity in dentate gyrus granule cells is required for detonation. Whether single unitary excitatory postsynaptic potentials (EPSPs) trigger spikes in CA3 neurons remains unknown. Mossy fiber synapses exhibit both pronounced short-term facilitation and uniquely large post-tetanic potentiation (PTP). We tested whether PTP could convert mossy fiber synapses from subdetonator into detonator mode, using a recently developed method to selectively and noninvasively stimulate individual presynaptic terminals in rat brain slices. Unitary EPSPs failed to initiate a spike in CA3 neurons under control conditions, but reliably discharged them after induction of presynaptic short-term plasticity. Remarkably, PTP switched mossy fiber synapses into full detonators for tens of seconds. Plasticity-dependent detonation may be critical for efficient coding, storage, and recall of information in the granule cell–CA3 cell network. DOI: http://dx.doi.org/10.7554/eLife.17977.001 PMID:27780032

  2. Age-related dysfunctions of the autophagy lysosomal pathway in hippocampal pyramidal neurons under proteasome stress.

    Science.gov (United States)

    Gavilán, Elena; Pintado, Cristina; Gavilan, Maria P; Daza, Paula; Sánchez-Aguayo, Inmaculada; Castaño, Angélica; Ruano, Diego

    2015-05-01

    Autophagy plays a key role in the maintenance of cellular homeostasis, and autophagy deregulation gives rise to severe disorders. Many of the signaling pathways regulating autophagy under stress conditions are still poorly understood. Using a model of proteasome stress in rat hippocampus, we have characterized the functional crosstalk between the ubiquitin proteasome system and the autophagy-lysosome pathway, identifying also age-related modifications in the crosstalk between both proteolytic systems. Under proteasome inhibition, both autophagy activation and resolution were efficiently induced in young but not in aged rats, leading to restoration of protein homeostasis only in young pyramidal neurons. Importantly, proteasome stress inhibited glycogen synthase kinase-3β in young but activated in aged rats. This age-related difference could be because of a dysfunction in the signaling pathway of the insulin growth factor-1 under stress situations. Present data highlight the potential role of glycogen synthase kinase-3β in the coordination of both proteolytic systems under stress situation, representing a key molecular target to sort out this deleterious effect.

  3. Culturally Responsive Pyramid Model Practices: Program-Wide Positive Behavior Support for Young Children

    Science.gov (United States)

    Allen, Rosemarie; Steed, Elizabeth A.

    2016-01-01

    This conceptual article reviews current research on racial disparities in disciplinary practices in early childhood education and work to address these issues within a positive behavior support (PBS) framework. Building largely on the Pyramid Model, recommendations and a culturally responsive approach are suggested for use within a program-wide…

  4. Trimethyltin (TMT) neurotoxicity in organotypic rat hippocampal slice cultures

    DEFF Research Database (Denmark)

    Noraberg, J; Gramsbergen, J B; Fonnum, F

    1998-01-01

    The neurotoxic effects of trimethyltin (TMT) on the hippocampus have been extensively studied in vivo. In this study, we examined whether the toxicity of TMT to hippocampal neurons could be reproduced in organotypic brain slice cultures in order to test the potential of this model for neurotoxico......The neurotoxic effects of trimethyltin (TMT) on the hippocampus have been extensively studied in vivo. In this study, we examined whether the toxicity of TMT to hippocampal neurons could be reproduced in organotypic brain slice cultures in order to test the potential of this model...... for neurotoxicological studies, including further studies of neurotoxic mechanisms of TMT. Four-week-old cultures, derived from 7-day-old donor rats and grown in serum-free medium, were exposed to TMT (0.5-100 microM) for 24 h followed by 24 h in normal medium. TMT-induced neurodegeneration was then monitored by (a...... of TMT neurotoxicity....

  5. Dopamine Inhibits High-Frequency Stimulation-Induced Long-Term Potentiation of Intrinsic Excitability in CA1 Hippocampal Pyramidal Neurons

    Directory of Open Access Journals (Sweden)

    Chun-ling Wei

    2012-09-01

    Full Text Available The efficiency of neural circuits is modified by changes not only in synaptic strength, but also in intrinsic excitability of neurons. In CA1 hippocampal pyramidal neurons, bidirectional changes in the intrinsic excitability are often presented after induction of synaptic long-term potentiation or depression. This plasticity of intrinsic excitability has been identified as a cellular correlate of learning. Besides, behavioral learning often involves action of reinforcement or rewarding mediated by dopamine (DA. Here, we examined how DA influences the intrinsic plasticity of CA1 hippocampal pyramidal neurons when high-frequency stimulation (HFS was applied to Schaffer collaterals. The results showed that DA inhibits the decrease in rheobase and increase in mean firing rate of pyramidal neurons induced by HFS, and that this inhibition was abolished by the D1-like receptor antagonist SCH23390 but not by the D2-like receptor antagonist sulpiride. The results suggest that DA inhibits the potentiation of excitability induced by presynaptic HFS, and that this inhibition depends on the activation of D1-like receptors.

  6. Characterization of altered intrinsic excitability in hippocampal CA1 pyramidal cells of the Aβ-overproducing PDAPP mouse☆

    Science.gov (United States)

    Kerrigan, T.L.; Brown, J.T.; Randall, A.D.

    2014-01-01

    Transgenic mice that accumulate Aβ peptides in the CNS are commonly used to interrogate functional consequences of Alzheimer's disease-associated amyloidopathy. In addition to changes to synaptic function, there is also growing evidence that changes to intrinsic excitability of neurones can arise in these models of amyloidopathy. Furthermore, some of these alterations to intrinsic properties may occur relatively early within the age-related progression of experimental amyloidopathy. Here we report a detailed comparison between the intrinsic excitability properties of hippocampal CA1 pyramidal neurones in wild-type (WT) and PDAPP mice. The latter is a well-established model of Aβ accumulation which expresses human APP harbouring the Indiana (V717F) mutation. At the age employed in this study (9–10 months) CNS Abeta was elevated in PDAPP mice but significant plaque pathology was absent. PDAPP mice exhibited no differences in subthreshold intrinsic properties including resting potential, input resistance, membrane time constant and sag. When CA1 cells of PDAPP mice were given depolarizing stimuli of various amplitudes they initially fired at a higher frequency than WT cells. Commensurate with this, PDAPP cells exhibited a larger fast afterdepolarizing potential. PDAPP mice had narrower spikes but action potential threshold, rate of rise and peak were not different. Thus not all changes seen in our previous studies of amyloidopathy models were present in PDAPP mice; however, narrower spikes, larger ADPs and the propensity to fire at higher frequencies were consistent with our prior work and thus may represent robust, cross-model, indices of amyloidopathy. This article is part of a Special Issue entitled ‘Neurodevelopment Disorder’. PMID:24055500

  7. Unique somato-dendritic distribution pattern of Kv4.2 channels on hippocampal CA1 pyramidal cells.

    Science.gov (United States)

    Kerti, Katalin; Lorincz, Andrea; Nusser, Zoltan

    2012-01-01

    A-type K(+) current (I(A)) plays a critical role in controlling the excitability of pyramidal cell (PC) dendrites. In vitro dendritic patch-pipette recordings have demonstrated a prominent, sixfold increase in I(A) density along the main apical dendrites of rat hippocampal CA1 PCs. In these cells, I(A) is mediated by Kv4.2 subunits, whose precise subcellular distribution and densities in small-diameter oblique dendrites and dendritic spines are still unknown. Here we examined the densities of the Kv4.2 subunit in 13 axo-somato-dendritic compartments of CA1 PCs using a highly sensitive, high-resolution quantitative immunogold localization method (sodium dodecyl sulphate-digested freeze-fracture replica-labelling). Only an approximately 70% increase in Kv4.2 immunogold density was observed along the proximo-distal axis of main apical dendrites in the stratum radiatum with a slight decrease in density in stratum lacunosum-moleculare. A similar pattern was detected for all dendritic compartments, including main apical dendrites, small-diameter oblique dendrites and dendritic spines. The specificity of the somato-dendritic labelling was confirmed in Kv4.2(-/-) tissue. No specific immunolabelling for the Kv4.2 subunit was found in SNAP-25-containing presynaptic axons. Our results demonstrate a novel distribution pattern of a voltage-gated ion channel along the somato-dendritic surface of CA1 PCs, and suggest that the increase in the I(A) along the proximo-distal axis of PC dendrites cannot be solely explained by a corresponding increase in Kv4.2 channel number.

  8. Intrinsic Ca2+-dependent theta oscillations in apical dendrites of hippocampal CA1 pyramidal cells in vitro.

    Science.gov (United States)

    Hansen, Allan Kjeldsen; Nedergaard, Steen; Andreasen, Mogens

    2014-08-01

    Behavior-associated theta-frequency oscillation in the hippocampal network involves a patterned activation of place cells in the CA1, which can be accounted for by a somatic-dendritic interference model predicting the existence of an intrinsic dendritic oscillator. Here we describe an intrinsic oscillatory mechanism in apical dendrites of in vitro CA1 pyramidal cells, which is induced by suprathreshold depolarization and consists of rhythmic firing of slow spikes in the theta-frequency band. The incidence of slow spiking (29%) increased to 78% and 100% in the presence of the β-adrenergic agonist isoproterenol (2 μM) or 4-aminopyridine (2 mM), respectively. Prior depolarization facilitated the induction of slow spiking. Applied electrical field polarization revealed a distal dendritic origin of slow spikes. The oscillations were largely insensitive to tetrodotoxin, but blocked by nimodipine (10 μM), indicating that they depend on activation of L-type Ca2+ channels. Antagonists of T-, R-, N-, and P/Q-type Ca2+ channels had no detectable effect. The slow spike dimension and frequency was sensitive to 4-aminopyridine (0.1-2 mM) and TEA (10 mM), suggesting the contribution from voltage-dependent K+ channels to the oscillation mechanism. α-Dendrotoxin (10 μM), stromatoxin (2 μM), iberiotoxin (0.2 μM), apamin (0.5 μM), linorpidine (30 μM), and ZD7288 (20 μM) were without effect. Oscillations induced by sine-wave current injection or theta-burst synaptic stimulation were voltage-dependently attenuated by nimodipine, indicating an amplifying function of L-type Ca2+ channels on imposed signals. These results show that the apical dendrites have intrinsic oscillatory properties capable of generating rhythmic voltage fluctuations in the theta-frequency band.

  9. GluN2D-containing NMDA receptors-mediate synaptic currents in hippocampal interneurons and pyramidal cells in juvenile mice

    Directory of Open Access Journals (Sweden)

    Jakob evon Engelhardt

    2015-03-01

    Full Text Available The differential regulation of the two major N-methyl-D-aspartate receptor (NMDAR subunits GluN2A and GluN2B during development in forebrain pyramidal cells has been thoroughly investigated. In contrast, much less is known about the role of GluN2D, which is expressed at low levels and is downregulated following the second postnatal week. However, it appears that few cells, presumably interneurons, continue to express GluN2D also in juvenile mice. To investigate which hippocampal cell types express this subunit, we generated transgenic mice with EGFP-tagged GluN2D receptors. The expression of the transgene was confined to hippocampal interneurons, most of which were parvalbumin- and/or somatostatin-positive. Electrophysiological and morphological analyses showed that GluN2D was present mainly in fast spiking basket and axo-axonic cells. Based on pharmacological evidence and electrophysiological analysis of GluN2D knockout mice, we conclude that GluN2D-containing NMDARs mediate synaptic currents in hippocampal interneurons of young and juvenile mice and in CA1 pyramidal neurons of newborn mice.

  10. Colchicine induces apoptosis in organotypic hippocampal slice cultures

    DEFF Research Database (Denmark)

    Kristensen, Bjarne W; Noer, Helle; Gramsbergen, Jan Bert

    2003-01-01

    The microtubule-disrupting agent colchicine is known to be particular toxic for certain types of neurons, including the granule cells of the dentate gyrus. In this study we investigated whether colchicine could induce such neuron-specific degeneration in developing (1 week in vitro) and mature (3...... weeks in vitro) organotypic hippocampal slice cultures and whether the induced cell death was apoptotic and/or necrotic. When applied to 1-week-old cultures for 48 h, colchicine induced primarily apoptotic, but also a minor degree of necrotic cell death in the dentate granule cells, as investigated...... the formation of active caspase 3 protein and apoptotic nuclei induced by colchicine, but the formation of necrotic nuclei increased correspondingly and the PI uptake was unaffected. We conclude that colchicine induces caspase 3-dependent apoptotic cell death of dentate granule cells in hippocampal brain slice...

  11. Appearance and distribution of peptidergic neurotransmitters in hippocampal primary culture

    OpenAIRE

    Thiele, Theodor

    2012-01-01

    The internal structure of the hippocampus, especially the development of neuronal circuits, is the subject of current research. The hippocampal primary culture represents a suitable model to study neuronal development and the impact of isolated stimuli and noxious. Focus of the following considerations are the neurons of the hippocampus, especially the peptidergic neurotransmitters somatostatin (SS), neuropeptide Y (NPY), vasoactive intestinal peptide (VIP) and cholecystokinin (CCK). By us...

  12. Low concentrations of alcohol inhibit BDNF-dependent GABAergic plasticity via L-type Ca2+ channel inhibition in developing CA3 hippocampal pyramidal neurons.

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    Zucca, Stefano; Valenzuela, C Fernando

    2010-05-12

    Fetal alcohol spectrum disorder (FASD) is associated with learning and memory alterations that could be, in part, a consequence of hippocampal damage. The CA3 hippocampal subfield is one of the regions affected by ethanol (EtOH), including exposure during the third trimester-equivalent (i.e., neonatal period in rats). However, the mechanism of action of EtOH is poorly understood. In CA3 pyramidal neurons from neonatal rats, dendritic BDNF release causes long-term potentiation of the frequency of GABAA receptor-mediated spontaneous postsynaptic currents (LTP-GABAA) and this mechanism is thought to play a role in GABAergic synapse maturation. Here, we show that short- and long-term exposure of neonatal male rats to low EtOH concentrations abolishes LTP-GABAA by inhibiting L-type voltage-gated Ca2+ channels. These findings support the recommendation that even light drinking should be avoided during pregnancy.

  13. Glutamic acid decarboxylase-67-positive hippocampal interneurons undergo a permanent reduction in number following kainic acid-induced degeneration of ca3 pyramidal neurons.

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    Shetty, A K; Turner, D A

    2001-06-01

    Kainic acid (KA)-induced degeneration of CA3 pyramidal neurons leads to synaptic reorganization and hyperexcitability in both dentate gyrus and CA1 region of the hippocampus. We hypothesize that the substrate for hippocampal inhibitory circuitry incurs significant and permanent alterations following degeneration of CA3 pyramidal neurons. We quantified changes in interneuron density (N(v)) in all strata of the dentate gyrus and the CA1 and CA3 subfields of adult rats at 1, 4, and 6 months following intracerebroventricular (icv) KA administration, using glutamic acid decarboxylase-67 (GAD-67) immunocytochemistry. At 1 month postlesion, GAD-67-positive interneuron density was significantly reduced in all strata of every hippocampal region except stratum pyramidale of CA1. The reduction in GAD-67-positive interneuron density either persisted or exacerbated at 4 and 6 months postlesion in every stratum of all hippocampal regions. Further, the soma of remaining GAD-67-positive interneurons in dentate gyrus and CA3 subfield showed significant hypertrophy. Thus, both permanent reductions in the density of GAD-67-positive interneurons in all hippocampal regions and somatic hypertrophy of remaining GAD-67-positive interneurons in dentate gyrus and CA3 subfield occur following icv KA. In contrast, the density of interneurons visualized with Nissl in CA1 and CA3 regions was nearly equivalent to that in the intact hippocampus at all postlesion time points. Collectively, these results suggest that persistent reductions in GAD-67-positive interneuron density observed throughout the hippocampus following CA3 lesion are largely due to a permanent loss of GAD-67 expression in a significant fraction of interneurons, rather than widespread degeneration of interneurons. Nevertheless, a persistent decrease in interneuron activity, as evidenced by permanent down-regulation of GAD-67 in a major fraction of interneurons, would likely enhance the degree of hyperexcitability in the CA3

  14. Repetitive magnetic stimulation induces plasticity of excitatory postsynapses on proximal dendrites of cultured mouse CA1 pyramidal neurons.

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    Lenz, Maximilian; Platschek, Steffen; Priesemann, Viola; Becker, Denise; Willems, Laurent M; Ziemann, Ulf; Deller, Thomas; Müller-Dahlhaus, Florian; Jedlicka, Peter; Vlachos, Andreas

    2015-11-01

    Repetitive transcranial magnetic stimulation (rTMS) of the human brain can lead to long-lasting changes in cortical excitability. However, the cellular and molecular mechanisms which underlie rTMS-induced plasticity remain incompletely understood. Here, we used repetitive magnetic stimulation (rMS) of mouse entorhino-hippocampal slice cultures to study rMS-induced plasticity of excitatory postsynapses. By employing whole-cell patch-clamp recordings of CA1 pyramidal neurons, local electrical stimulations, immunostainings for the glutamate receptor subunit GluA1 and compartmental modeling, we found evidence for a preferential potentiation of excitatory synapses on proximal dendrites of CA1 neurons (2-4 h after stimulation). This rMS-induced synaptic potentiation required the activation of voltage-gated sodium channels, L-type voltage-gated calcium channels and N-methyl-D-aspartate-receptors. In view of these findings we propose a cellular model for the preferential strengthening of excitatory synapses on proximal dendrites following rMS in vitro, which is based on a cooperative effect of synaptic glutamatergic transmission and postsynaptic depolarization.

  15. Acute alterations of somatodendritic action potential dynamics in hippocampal CA1 pyramidal cells after kainate-induced status epilepticus in mice.

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    Daniel Minge

    Full Text Available Pathophysiological remodeling processes at an early stage of an acquired epilepsy are critical but not well understood. Therefore, we examined acute changes in action potential (AP dynamics immediately following status epilepticus (SE in mice. SE was induced by intraperitoneal (i.p. injection of kainate, and behavioral manifestation of SE was monitored for 3-4 h. After this time interval CA1 pyramidal cells were studied ex vivo with whole-cell current-clamp and Ca(2+ imaging techniques in a hippocampal slice preparation. Following acute SE both resting potential and firing threshold were modestly depolarized (2-5 mV. No changes were seen in input resistance or membrane time constant, but AP latency was prolonged and AP upstroke velocity reduced following acute SE. All cells showed an increase in AP halfwidth and regular (rather than burst firing, and in a fraction of cells the notch, typically preceding spike afterdepolarization (ADP, was absent following acute SE. Notably, the typical attenuation of backpropagating action potential (b-AP-induced Ca(2+ signals along the apical dendrite was strengthened following acute SE. The effects of acute SE on the retrograde spread of excitation were mimicked by applying the Kv4 current potentiating drug NS5806. Our data unveil a reduced somatodendritic excitability in hippocampal CA1 pyramidal cells immediately after acute SE with a possible involvement of both Na(+ and K(+ current components.

  16. Effects of deprivation of oxygen or glucose on the neural activity in the guinea pig hippocampal slice--intracellular recording study of pyramidal neurons.

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    Takata, T; Okada, Y

    1995-06-12

    The block of synaptic transmission and neural activity during deprivation of oxygen or glucose has been simply attributed to the lack of energy due to the disorder of energy production. To clarify the interrelation between neural activity and energy metabolism during hypoxia or glucose deprivation, we studied the changes in ATP levels and electrical events of pyramidal neurons in the CA3 region and [Ca2+]i mobilization of the dendritic and cellular region of CA3 area, using guinea pig hippocampal slices. The studies of field potentials and intracellular recording from the pyramidal cell of CA3 area during hypoxia or glucose deprivation revealed that the cessation of synaptic activity and the depolarization of resting potential occurred earlier than during glucose deprivation while the increase of [Ca2+]i was slow during hypoxia but rapid during glucose deprivation although the ATP level of CA3 area was maintained at its original level for 20 min during both conditions. When glucose was replaced by lactate, ATP concentration was not reduced but the electrical activity decayed and [Ca2+]i increased with the similar time course as observed during lack of glucose, only. These results suggest that different mechanisms underlie the block of synaptic transmission in the CA3 pyramidal neurons during hypoxia and glucose deprivation and that lactate cannot substitute for glucose in the maintenance of neural activity.

  17. The GLP-1 Receptor Agonist Exendin-4 and Diazepam Differentially Regulate GABAA Receptor-Mediated Tonic Currents in Rat Hippocampal CA3 Pyramidal Neurons.

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    Sergiy V Korol

    Full Text Available Glucagon-like peptide-1 (GLP-1 is a metabolic hormone that is secreted in a glucose-dependent manner and enhances insulin secretion. GLP-1 receptors are also found in the brain where their signalling affects neuronal activity. We have previously shown that the GLP-1 receptor agonists, GLP-1 and exendin-4 enhanced GABA-activated synaptic and tonic currents in rat hippocampal CA3 pyramidal neurons. The hippocampus is the centre for memory and learning and is important for cognition. Here we examined if exendin-4 similarly enhanced the GABA-activated currents in the presence of the benzodiazepine diazepam. In whole-cell recordings in rat brain slices, diazepam (1 μM, an allosteric positive modulator of GABAA receptors, alone enhanced the spontaneous inhibitory postsynaptic current (sIPSC amplitude and frequency by a factor of 1.3 and 1.6, respectively, and doubled the tonic GABAA current normally recorded in the CA3 pyramidal cells. Importantly, in the presence of exendin-4 (10 nM plus diazepam (1 μM, only the tonic but not the sIPSC currents transiently increased as compared to currents recorded in the presence of diazepam alone. The results suggest that exendin-4 potentiates a subpopulation of extrasynaptic GABAA receptors in the CA3 pyramidal neurons.

  18. Elevated potassium elicits recurrent surges of large GABAA-receptor-mediated post-synaptic currents in hippocampal CA3 pyramidal neurons.

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    Shin, Damian Seung-Ho; Yu, Wilson; Sutton, Alex; Calos, Megan; Carlen, Peter Louis

    2011-03-01

    Previously, we found that rat hippocampal CA3 interneurons become hyperactive with increasing concentrations of extracellular K(+) up to 10 mM. However, it is unclear how this enhanced interneuronal activity affects pyramidal neurons. Here we voltage-clamped rat hippocampal CA3 pyramidal neurons in vitro at 0 mV to isolate γ-aminobutyric acid (GABA)-activated inhibitory post-synaptic currents (IPSCs) and measured these in artificial cerebrospinal fluid (aCSF) and with 10 mM K(+) bath perfusion. In aCSF, small IPSCs were present with amplitudes of 0.053 ± 0.007 nA and a frequency of 0.27 ± 0.14 Hz. With 10 mM K(+) perfusion, IPSCs increased greatly in frequency and amplitude, culminating in surge events with peak amplitudes of 0.56 ± 0.08 nA, that appeared and disappeared cyclically with durations lasting 2.02 ± 0.37 min repeatedly, up to 10 times over a 30-min bath perfusion of elevated K(+). These large IPSCs were GABA(A)-receptor mediated and did not involve significant desensitization of this receptor. Perfusion of a GABA transporter inhibitor (NO-711), glutamate receptor inhibitors CNQX and APV, or a gap junctional blocker (carbenoxolone) prevented the resurgence of large IPSCs. Pressure ejected sucrose resulted in the abolishment of subsequent surges. No elevated K(+)-mediated surges were observed in CA3 interneurons from the stratum oriens layer. In conclusion, these cyclic large IPSC events observable in CA3 pyramidal neurons in 10 mM KCl may be due to transient GABA depletion from continuously active interneuronal afferents.

  19. Enhanced intrinsic excitability and EPSP-spike coupling accompany enriched environment-induced facilitation of LTP in hippocampal CA1 pyramidal neurons.

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    Malik, Ruchi; Chattarji, Sumantra

    2012-03-01

    Environmental enrichment (EE) is a well-established paradigm for studying naturally occurring changes in synaptic efficacy in the hippocampus that underlie experience-induced modulation of learning and memory in rodents. Earlier research on the effects of EE on hippocampal plasticity focused on long-term potentiation (LTP). Whereas many of these studies investigated changes in synaptic weight, little is known about potential contributions of neuronal excitability to EE-induced plasticity. Here, using whole-cell recordings in hippocampal slices, we address this gap by analyzing the impact of EE on both synaptic plasticity and intrinsic excitability of hippocampal CA1 pyramidal neurons. Consistent with earlier reports, EE increased contextual fear memory and dendritic spine density on CA1 cells. Furthermore, EE facilitated LTP at Schaffer collateral inputs to CA1 pyramidal neurons. Analysis of the underlying causes for enhanced LTP shows EE to increase the frequency but not amplitude of miniature excitatory postsynaptic currents. However, presynaptic release probability, assayed using paired-pulse ratios and use-dependent block of N-methyl-d-aspartate receptor currents, was not affected. Furthermore, CA1 neurons fired more action potentials (APs) in response to somatic depolarization, as well as during the induction of LTP. EE also reduced spiking threshold and after-hyperpolarization amplitude. Strikingly, this EE-induced increase in excitability caused the same-sized excitatory postsynaptic potential to fire more APs. Together, these findings suggest that EE may enhance the capacity for plasticity in CA1 neurons, not only by strengthening synapses but also by enhancing their efficacy to fire spikes-and the two combine to act as an effective substrate for amplifying LTP.

  20. [Electrophysiological properties of inhibitory neurones in cultured dissociated hippocampal cells].

    Science.gov (United States)

    Moskaliuk, A O; Kolodin, Iu O; Kravchenko, M O; Fedulova, S A; Veselovs'kyĭ, M S

    2004-01-01

    Electrophysiological properties of inhibitory (GABAergic) neurones were studied in dissociated hippocampal culture using simultaneous whole cell recordings from pairs of monosynaptically coupled neurons. Reliable identification of GABAergic neuron was performed by presence of monosynaptic inhibitory currents at postsynaptic cell in response to action potentials at stimulated cell. It was shown that GABAergic neurons in hippocampal culture are divided in two groups by their firing characteristics: first type generates action potentials at high frequency in response to injection of current (duration 0.5 s)--fast-spiking neurons (FS), cells from second type has no ability for high-frequency action potential generation--regular spiking neurons (RS). These two groups were distinguished by kinetic characteristics of action potentials, adaptation characteristics during continuous generation of action potentials and inhibitory effect making on postsynaptic cell. Application of potassium channel blocker 4-AP to somas of FS neurons in concentration, which selectively inhibits Kv3 potassium channels evoked reversible changes in kinetic of action potentials, frequency and adaptation characteristics during continuous generation of action potentials. It was concluded that there is hight level of expression of Kv3 potassium channels in the first group of neurons.

  1. Extrinsic and local glutamatergic inputs of the rat hippocampal CA1 area differentially innervate pyramidal cells and interneurons.

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    Takács, Virág T; Klausberger, Thomas; Somogyi, Peter; Freund, Tamás F; Gulyás, Attila I

    2012-06-01

    The two main glutamatergic pathways to the CA1 area, the Schaffer collateral/commissural input and the entorhinal fibers, as well as the local axons of CA1 pyramidal cells innervate both pyramidal cells and interneurons. To determine whether these inputs differ in their weights of activating GABAergic circuits, we have studied the relative proportion of pyramidal cells and interneurons among their postsynaptic targets in serial electron microscopic sections. Local axons of CA1 pyramidal cells, intracellularly labeled in vitro or in vivo, innervated a relatively high proportion of interneuronal postsynaptic targets (65.9 and 53.8%, in vitro and in vivo, respectively) in stratum (str.) oriens and alveus. In contrast, axons of in vitro labeled CA3 pyramidal cells in str. oriens and str. radiatum of the CA1 area made synaptic junctions predominantly with pyramidal cell spines (92.9%). The postsynaptic targets of anterogradely labeled medial entorhinal cortical boutons in CA1 str. lacunosum-moleculare were primarily pyramidal neuron dendritic spines and shafts (90.8%). The alvear group of the entorhinal afferents, traversing str. oriens, str. pyramidale, and str. radiatum showed a higher preference for innervating GABAergic cells (21.3%), particularly in str. oriens/alveus. These data demonstrate that different glutamatergic pathways innervate CA1 GABAergic cells to different extents. The results suggest that the numerically smaller CA1 local axonal inputs together with the alvear part of the entorhinal input preferentially act on GABAergic interneurons in contrast to the CA3, or the entorhinal input in str. lacunosum-moleculare. The results highlight differences in the postsynaptic target selection of the feed-forward versus recurrent glutamatergic inputs to the CA1 and CA3 areas.

  2. Age-Dependent Glutamate Induction of Synaptic Plasticity in Cultured Hippocampal Neurons

    Science.gov (United States)

    Ivenshitz, Miriam; Segal, Menahem; Sapoznik, Stav

    2006-01-01

    A common denominator for the induction of morphological and functional plasticity in cultured hippocampal neurons involves the activation of excitatory synapses. We now demonstrate massive morphological plasticity in mature cultured hippocampal neurons caused by a brief exposure to glutamate. This plasticity involves a slow, 70%-80% increase in…

  3. Excitatory synaptic activity is associated with a rapid structural plasticity of inhibitory synapses on hippocampal CA1 pyramidal cells.

    Science.gov (United States)

    Lushnikova, Irina; Skibo, Galina; Muller, Dominique; Nikonenko, Irina

    2011-04-01

    Synaptic activity, such as long-term potentiation (LTP), has been shown to induce morphological plasticity of excitatory synapses on dendritic spines through the spine head and postsynaptic density (PSD) enlargement and reorganization. Much less, however, is known about activity-induced morphological modifications of inhibitory synapses. Using an in vitro model of rat organotypic hippocampal slice cultures and electron microscopy, we studied activity-related morphological changes of somatic inhibitory inputs triggered by a brief oxygen-glucose deprivation (OGD) episode, a condition associated with a synaptic enhancement referred to as anoxic LTP and a structural remodeling of excitatory synapses. Three-dimensional reconstruction of inhibitory axo-somatic synapses at different times before and after brief OGD revealed important morphological changes. The PSD area significantly and markedly increased at synapses with large and complex PSDs, but not at synapses with simple, macular PSDs. Activity-related changes of PSD size and presynaptic bouton volume developed in a strongly correlated manner. Analyses of single and serial sections further showed that the density of inhibitory synaptic contacts on the cell soma did not change within 1 h after OGD. In contrast, the proportion of the cell surface covered with inhibitory PSDs, as well as the complexity of these PSDs significantly increased, with less macular PSDs and more complex, segmented shapes. Together, these data reveal a rapid activity-related restructuring of somatic inhibitory synapses characterized by an enlargement and increased complexity of inhibitory PSDs, providing a new mechanism for a quick adjustment of the excitatory-inhibitory balance. This article is part of a Special Issue entitled 'Synaptic Plasticity & Interneurons'.

  4. Sub-millisecond firing synchrony of closely neighboring pyramidal neurons in hippocampal CA1 of rats during delayed non-matching to sample task

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    Susumu Takahashi

    2009-09-01

    Full Text Available Firing synchrony among neurons is thought to play functional roles in several brain regions. In theoretical analyses, firing synchrony among neurons within sub-millisecond precision is feasible to convey information. However, little is known about the occurrence and the functional significance of the sub-millisecond synchrony among closely neighboring neurons in the brain of behaving animals because of a technical issue: spikes simultaneously generated from closely neighboring neurons are overlapped in the extracellular space and are not easily separated. As described herein, using a unique spike sorting technique based on independent component analysis together with extracellular 12-channel multi-electrodes (dodecatrodes, we separated such overlapping spikes and investigated the firing synchrony among closely neighboring pyramidal neurons in the hippocampal CA1 of rats during a delayed non-matching to sample task. Results showed that closely neighboring pyramidal neurons in the hippocampal CA1 can co-fire with sub-millisecond precision. The synchrony generally co-occurred with the firing rate modulation in relation to both internal (retention and comparison and external (stimulus input and motor output events during the task. However, the synchrony occasionally occurred in relation to stimulus inputs even when rate modulation was clearly absent, suggesting that the synchrony is not simply accompanied with firing rate modulation and that the synchrony and the rate modulation might code similar information independently. We therefore conclude that the sub-millisecond firing synchrony in the hippocampus is an effective carrier for propagating information—as represented by the firing rate modulations—to downstream neurons.

  5. Expression profile analysis of hippocampal CA1 pyramidal neurons in aged Ts65Dn mice, a model of Down syndrome (DS) and Alzheimer's disease (AD).

    Science.gov (United States)

    Alldred, Melissa J; Lee, Sang Han; Petkova, Eva; Ginsberg, Stephen D

    2015-09-01

    Down syndrome (DS) is caused by the triplication of human chromosome 21 (HSA21) and is the most common genetic cause of intellectual disability, with individuals having deficits in cognitive function including hippocampal learning and memory and neurodegeneration of cholinergic basal forebrain neurons, a pathological hallmark of Alzheimer's disease (AD). To date, the molecular underpinnings driving this pathology have not been elucidated. The Ts65Dn mouse is a segmental trisomy model of DS and like DS/AD pathology, displays age-related cognitive dysfunction and basal forebrain cholinergic neuron (BFCN) degeneration. To determine molecular and cellular changes important for elucidating mechanisms of neurodegeneration in DS/AD pathology, expression profiling studies were performed. Molecular fingerprinting of homogeneous populations of Cornu Ammonis 1 (CA1) pyramidal neurons was performed via laser capture microdissection followed by Terminal Continuation RNA amplification combined with custom-designed microarray analysis and subsequent validation of individual transcripts by qPCR and protein analysis via immunoblotting. Significant alterations were observed within CA1 pyramidal neurons of aged Ts65Dn mice compared to normal disomic (2N) littermates, notably in excitatory and inhibitory neurotransmission receptor families and neurotrophins, including brain-derived neurotrophic factor as well as several cognate neurotrophin receptors. Examining gene and protein expression levels after the onset of BFCN degeneration elucidated transcriptional and translational changes in neurons within a vulnerable circuit that may cause the AD-like pathology seen in DS as these individuals age, and provide rational targets for therapeutic interventions.

  6. Weak sinusoidal electric fields entrain spontaneous Ca transients in the dendritic tufts of CA1 pyramidal cells in rat hippocampal slice preparations.

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    Maeda, Kazuma; Maruyama, Ryuichi; Nagae, Toru; Inoue, Masashi; Aonishi, Toru; Miyakawa, Hiroyoshi

    2015-01-01

    Neurons might interact via electric fields and this notion has been referred to as ephaptic interaction. It has been shown that various types of ion channels are distributed along the dendrites and are capable of supporting generation of dendritic spikes. We hypothesized that generation of dendritic spikes play important roles in the ephaptic interactions either by amplifying the impact of electric fields or by providing current source to generate electric fields. To test if dendritic activities can be modulated by electric fields, we developed a method to monitor local Ca-transients in the dendrites of a neuronal population in acute rat hippocampal slices by applying spinning-disk confocal microscopy and multi-cell dye loading technique. In a condition in which the dendrites of CA1 pyramidal neurons show spontaneous Ca-transients due to added 50 μM 4-aminopyridine to the bathing medium and adjusted extracellular potassium concentration, we examined the impact of sinusoidal electric fields on the Ca-transients. We have found that spontaneously occurring fast-Ca-transients in the tufts of the apical dendrites of CA1 pyramidal neurons can be blocked by applying 1 μM tetrodotoxin, and that the timing of the transients become entrained to sub-threshold 1-4 Hz electric fields with an intensity as weak as 0.84 mV/mm applied parallel to the somato-dendritic axis of the neurons. The extent of entrainment increases with intensity below 5 mV/mm, but does not increase further over the range of 5-20 mV/mm. These results suggest that population of pyramidal cells might be able to detect electric fields with biologically relevant intensity by modulating the timing of dendritic spikes.

  7. Complement C1q expression induced by Abeta in rat hippocampal organotypic slice cultures.

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    Fan, Rong; Tenner, Andrea J

    2004-02-01

    Amyloid beta peptide (Abeta) is a major component of senile plaques, one of the principle pathological features in Alzheimer's disease (AD) brains. Fibrillar Abeta has been shown to bind C1 via C1q, the recognition component of the classical complement pathway, resulting in the activation of the complement pathway, thereby initiating an inflammatory cascade in the brain. C1q has also been shown to enhance phagocytic activities of microglia, which could benefit in clearance of apoptotic cells or cellular debris. To begin to define the role of C1q in tissue injury mediated by Abeta, we assessed the appearance of C1q in hippocampal slice cultures treated with freshly solubilized or fibrillar Abeta 1-42. Here we demonstrate a dose- and time-dependent uptake of exogenously applied Abeta by pyramidal neurons in organotypic slice cultures from rat hippocampus. Importantly, when slices were immunostained with antibody against rat C1q, a distinct reactivity for C1q in cells within the neuronal cell layer of cornu ammonis (CA) of hippocampus, primarily the CA1/CA2, was observed in the Abeta-treated slices. No such immunoreactivity was detected in untreated cultures or upon addition of control peptides. ELISA assays also showed an increase in C1q in tissue extracts from slices of the treated group. Similarly, the mRNA level of C1q in slices was increased within 24 h after Abeta treatment. These data demonstrate that upon exposure to Abeta, C1q is expressed in neurons in this organotypic system. The induction of C1q may be an early, perhaps beneficial, tissue or cellular response to injury triggered by particular pathogenic stimuli.

  8. Type I TARPs promote dendritic growth of early postnatal neocortical pyramidal cells in organotypic cultures.

    Science.gov (United States)

    Hamad, Mohammad I K; Jack, Alexander; Klatt, Oliver; Lorkowski, Markus; Strasdeit, Tobias; Kott, Sabine; Sager, Charlotte; Hollmann, Michael; Wahle, Petra

    2014-04-01

    The ionotropic α-amino-3-hydroxy-5-methyl-4-isoxazole propionate glutamate receptors (AMPARs) have been implicated in the establishment of dendritic architecture. The transmembrane AMPA receptor regulatory proteins (TARPs) regulate AMPAR function and trafficking into synaptic membranes. In the current study, we employ type I and type II TARPs to modulate expression levels and function of endogenous AMPARs and investigate in organotypic cultures (OTCs) of rat occipital cortex whether this influences neuronal differentiation. Our results show that in early development [5-10 days in vitro (DIV)] only the type I TARP γ-8 promotes pyramidal cell dendritic growth by increasing spontaneous calcium amplitude and GluA2/3 expression in soma and dendrites. Later in development (10-15 DIV), the type I TARPs γ-2, γ-3 and γ-8 promote dendritic growth, whereas γ-4 reduced dendritic growth. The type II TARPs failed to alter dendritic morphology. The TARP-induced dendritic growth was restricted to the apical dendrites of pyramidal cells and it did not affect interneurons. Moreover, we studied the effects of short hairpin RNA-induced knockdown of endogenous γ-8 and showed a reduction of dendritic complexity and amplitudes of spontaneous calcium transients. In addition, the cytoplasmic tail (CT) of γ-8 was required for dendritic growth. Single-cell calcium imaging showed that the γ-8 CT domain increases amplitude but not frequency of calcium transients, suggesting a regulatory mechanism involving the γ-8 CT domain in the postsynaptic compartment. Indeed, the effect of γ-8 overexpression was reversed by APV, indicating a contribution of NMDA receptors. Our results suggest that selected type I TARPs influence activity-dependent dendritogenesis of immature pyramidal neurons.

  9. Epileptogenesis in organotypic hippocampal cultures has limited dependence on culture medium composition

    Science.gov (United States)

    Mahoney, Mark M.; Staley, Kevin J.

    2017-01-01

    Rodent organotypic hippocampal cultures spontaneously develop epileptiform activity after approximately 2 weeks in vitro and are increasingly used as a model of chronic post-traumatic epilepsy. However, organotypic cultures are maintained in an artificial environment (culture medium), which contains electrolytes, glucose, amino acids and other components that are not present at the same concentrations in cerebrospinal fluid (CSF). Therefore, it is possible that epileptogenesis in organotypic cultures is driven by these components. We examined the influence of medium composition on epileptogenesis. Epileptogenesis was evaluated by measurements of lactate and lactate dehydrogenase (LDH) levels (biomarkers of ictal activity and cell death, respectively) in spent culture media, immunohistochemistry and automated 3-D cell counts, and extracellular recordings from CA3 regions. Changes in culture medium components moderately influenced lactate and LDH levels as well as electrographic seizure burden and cell death. However, epileptogenesis occurred in any culture medium that was capable of supporting neural survival. We conclude that medium composition is unlikely to be the cause of epileptogenesis in the organotypic hippocampal culture model of chronic post-traumatic epilepsy. PMID:28225808

  10. Persistent Gliosis Interferes with Neurogenesis in Organotypic Hippocampal Slice Cultures.

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    Gerlach, Johannes; Donkels, Catharina; Münzner, Gert; Haas, Carola A

    2016-01-01

    Neurogenesis in the adult hippocampus has become an intensively investigated research topic, as it is essential for proper hippocampal function and considered to bear therapeutic potential for the replacement of pathologically lost neurons. On the other hand, neurogenesis itself is frequently affected by CNS insults. To identify processes leading to the disturbance of neurogenesis, we made use of organotypic hippocampal slice cultures (OHSC), which, for unknown reasons, lose their neurogenic potential during cultivation. In the present study, we show by BrdU/Prox1 double-immunostaining that the generation of new granule cells drops by 90% during the first week of cultivation. Monitoring neurogenesis dynamically in OHSC from POMC-eGFP mice, in which immature granule cells are endogenously labeled, revealed a gradual decay of the eGFP signal, reaching 10% of initial values within 7 days of cultivation. Accordingly, reverse transcription quantitative polymerase chain reaction analysis showed the downregulation of the neurogenesis-related genes doublecortin and Hes5, a crucial target of the stem cell-maintaining Notch signaling pathway. In parallel, we demonstrate a strong and long-lasting activation of astrocytes and microglial cells, both, morphologically and on the level of gene expression. Enhancement of astroglial activation by treating OHSC with ciliary neurotrophic factor accelerated the loss of neurogenesis, whereas treatment with indomethacin or an antagonist of the purinergic P2Y12 receptor exhibited potent protective effects on the neurogenic outcome. Therefore, we conclude that OHSC rapidly lose their neurogenic capacity due to persistent inflammatory processes taking place after the slice preparation. As inflammation is also considered to affect neurogenesis in many CNS pathologies, OHSC appear as a useful tool to study this interplay and its molecular basis. Furthermore, we propose that modification of glial activation might bear the therapeutic potential

  11. Persistent gliosis interferes with neurogenesis in organotypic hippocampal slice cultures

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    Johannes eGerlach

    2016-05-01

    Full Text Available Neurogenesis in the adult hippocampus has become an intensively investigated research topic, as it is essential for proper hippocampal function and considered to bear therapeutic potential for the replacement of pathologically lost neurons. On the other hand, neurogenesis itself is frequently affected by CNS insults. To identify processes leading to the disturbance of neurogenesis, we made use of organotypic hippocampal slice cultures (OHSC, which, for unknown reasons, lose their neurogenic potential during cultivation. In the present study, we show by BrdU/Prox1 double-immunostaining that the generation of new granule cells drops by 90% during the first week of cultivation. Monitoring neurogenesis dynamically in OHSC from POMC-eGFP mice, in which immature granule cells are endogenously labeled, revealed a gradual decay of the eGFP signal, reaching 10% of initial values within seven days of cultivation. Accordingly, RT-qPCR analysis showed the downregulation of the neurogenesis-related genes doublecortin and Hes5, a crucial target of the stem cell-maintaining Notch signaling pathway. In parallel, we demonstrate a strong and long-lasting activation of astrocytes and microglial cells, both, morphologically and on the level of gene expression. Enhancement of astroglial activation by treating OHSC with ciliary neurotrophic factor (CNTF accelerated the loss of neurogenesis, whereas treatment with indomethacin or an antagonist of the purinergic P2Y12 receptor exhibited potent protective effects on the neurogenic outcome. Therefore, we conclude that OHSC rapidly lose their neurogenic capacity due to persistent inflammatory processes taking place after the slice preparation. As inflammation is also considered to affect neurogenesis in many CNS pathologies, OHSC appear as a useful tool to study this interplay and its molecular basis. Furthermore, we propose that modification of glial activation might bear the therapeutic potential of enabling

  12. Delivery of recombinant alphavirus into hippocampal slice tissue culture.

    Science.gov (United States)

    Lundstrom, Kenneth

    2012-08-01

    The alphaviruses Semliki Forest virus (SFV) and Sindbis virus (SIN) have been used frequently as expression vectors in vitro and in vivo. Usually, these systems consist of replication-deficient vectors that require a helper vector for packaging of recombinant particles. Replication-proficient vectors have also been engineered. Alphaviral vectors can be used as nucleic-acid-based vectors (DNA and RNA) or infectious particles. High-titer viral production is achieved in alphaviruses facilitates studies in mammalian and nonmammalian cell lines, primary cells in culture, and in vivo. The strong preference for expression in neuronal cells has made alphaviruses particularly useful in neurobiological studies. Unfortunately, their strong cytotoxic effect on host cells, relatively short-term transient expression patterns, and the reasonably high cost of viral production remain drawbacks. However, novel mutant alphaviruses have shown reduced cytotoxicity and prolonged expression. This protocol describes gene delivery of recombinant alphavirus to hippocampal slice cultures. Organotypic slices are covered by a layer of glial cells that impedes the penetration of viral particles to the neurons. Thus, viral particles should be injected manually into the extracellular space of the tissue.

  13. Modulation of Hyperpolarization-Activated Cation Currents (Ih) by Ethanol in Rat Hippocampal CA3 Pyramidal Neurons

    OpenAIRE

    Licheri, Valentina

    2015-01-01

    It is well established that ethanol (EtOH), through the interaction with several membrane proteins, as well as intracellular pathways, is capable to modulate many neuronal function. Recent reports show that EtOH increases the firing rate of hippocampal GABAergic interneurons through the positive modulation of the hyperpolarization-activated cyclic nucleotide-gated (HCN) cation channels. This effect might be consistent with the increase of GABA release from presynaptic terminals...

  14. Chronic zinc exposure decreases the surface expression of NR2A-containing NMDA receptors in cultured hippocampal neurons.

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    Jia Zhu

    Full Text Available BACKGROUND: Zinc distributes widely in the central nervous system, especially in the hippocampus, amygdala and cortex. The dynamic balance of zinc is critical for neuronal functions. Zinc modulates the activity of N-methyl-D-aspartate receptors (NMDARs through the direct inhibition and various intracellular signaling pathways. Abnormal NMDAR activities have been implicated in the aetiology of many brain diseases. Sustained zinc accumulation in the extracellular fluid is known to link to pathological conditions. However, the mechanism linking this chronic zinc exposure and NMDAR dysfunction is poorly understood. METHODOLOGY/PRINCIPAL FINDINGS: We reported that chronic zinc exposure reduced the numbers of NR1 and NR2A clusters in cultured hippocampal pyramidal neurons. Whole-cell and synaptic NR2A-mediated currents also decreased. By contrast, zinc did not affect NR2B, suggesting that chronic zinc exposure specifically influences NR2A-containg NMDARs. Surface biotinylation indicated that zinc exposure attenuated the membrane expression of NR1 and NR2A, which might arise from to the dissociation of the NR2A-PSD-95-Src complex. CONCLUSIONS: Chronic zinc exposure perturbs the interaction of NR2A to PSD-95 and causes the disorder of NMDARs in hippocampal neurons, suggesting a novel action of zinc distinct from its acute effects on NMDAR activity.

  15. Closed head injury causes hyperexcitability in rat hippocampal CA1 but not in CA3 pyramidal cells.

    Science.gov (United States)

    Griesemer, Désirée; Mautes, Angelika M

    2007-12-01

    Traumatic brain injury frequently elicits epileptic seizures hours or days after the impact. The mechanisms on cellular level are poorly understood. Because posttraumatic epilepsy appears in many cases as a temporal-lobe epilepsy which originated the hippocampus, we studied trauma-induced hyperexcitability on the cellular level in this brain area. We used the model of closed head injury to analyse the electrophysiological changes in CA1 and CA3 pyramidal cells and in interneurones of the CA1 field, which is extremely sensitive to ischemia. We found that morphologically closed head injury (CHI) led to a gradual progressive, cell type specific time course in neuronal degeneration. To analyse electrophysiological impairment we measured resting membrane potential, recorded spontaneous action potentials and induced action potentials by current pulses at different times after CHI. We found a dramatic increase in the frequency of spontaneous action potentials of CA1 but not of CA3 pyramidal cells after CHI. This hyperexcitability was maximal at 2 h (4.5-fold higher than sham), was also observed at 24 h after CHI and disappeared after 3 days. We found that CA1 interneurones responded by a much weaker increase of AP frequency after CHI. We conclude that the strong hyperexcitability after CHI is cell-type specific and transient. The understanding of the complex neuronal interactions probably offers a promising possibility for pharmacological intervention to prevent posttraumatic epilepsy.

  16. Phasic and tonic type A γ-Aminobutryic acid receptor mediated effect of Withania somnifera on mice hippocampal CA1 pyramidal Neurons

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    Janardhan Prasad Bhattarai

    2014-01-01

    Full Text Available Background: In Nepali and Indian system of traditional medicine, Withania somnifera (WS is considered as a rejuvenative medicine to maintain physical and mental health and has also been shown to improve memory consolidation. Objective: In this study, a methanolic extract of WS (mWS was applied on mice hippocampal CA1 neurons to identify the receptors activated by the WS. Materials and Methods: The whole cell patch clamp recordings were performed on CA1 pyramidal neurons from immature mice (7-20 postnatal days. The cells were voltage clamped at -60 mV. Extract of WS root were applied to identify the effect of mWS. Results: The application of mWS (400 ng/μl induced remarkable inward currents (-158.1 ± 28.08 pA, n = 26 on the CA1 pyramidal neurons. These inward currents were not only reproducible but also concentration dependent. mWS-induced inward currents remained persistent in the presence of amino acid receptor blocking cocktail (AARBC containing blockers for the ionotropic glutamate receptors, glycine receptors and voltage-gated Na + channel (Control: -200.3 ± 55.42 pA, AARBC: -151.5 ± 40.58 pA, P > 0.05 suggesting that most of the responses by mWS are postsynaptic events. Interestingly, these inward currents were almost completely blocked by broad GABA A receptor antagonist, bicuculline- 20 μM (BIC (BIC: -1.46 ± 1.4 pA, P < 0.001, but only partially by synaptic GABA A receptor blocker gabazine (1 μM (GBZ: -18.26 ± 4.70 pA, P < 0.01. Conclusion: These results suggest that WS acts on synaptic/extrasynaptic GABA A receptors and may play an important role in the process of memory and neuroprotection via activation of synaptic and extrasynaptic GABA A receptors.

  17. Latent N-methyl-D-aspartate receptors in the recurrent excitatory pathway between hippocampal CA1 pyramidal neurons: Ca(2+)-dependent activation by blocking A1 adenosine receptors.

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    Klishin, A; Tsintsadze, T; Lozovaya, N; Krishtal, O

    1995-01-01

    When performed at increased external [Ca2+]/[Mg2+] ratio (2.5 mM/0.5 mM), temporary block of A1 adenosine receptors in hippocampus [by 8-cyclopentyltheophylline (CPT)] leads to a dramatic and irreversible change in the excitatory postsynaptic current (EPSC) evoked by Schaffer collateral/commissural (SCC) stimulation and recorded by in situ patch clamp in CA1 pyramidal neurons. The duration of the EPSC becomes stimulus dependent, increasing with increase in stimulus strength. The later occurring component of the EPSC is carried through N-methyl-D-aspartate (NMDA) receptor-operated channels but disappears under either the NMDA antagonist 2-amino-5-phosphonovaleric acid (APV) or the non-NMDA antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX). These findings indicate that the late component of the SCC-evoked EPSC is polysynaptic: predominantly non-NMDA receptor-mediated SCC inputs excite CA1 neurons that recurrently excite each other by predominantly NDMA receptor-mediated synapses. These recurrent connections are normally silent but become active after CPT treatment, leading to enhancement of the late component of the EPSC. The activity of these connections is maintained for at least 2 hr after CPT removal. When all functional NMDA receptors are blocked by dizocilpine maleate (MK-801), subsequent application of CPT leads to a partial reappearance of NMDA receptor-mediated EPSCs evoked by SCC stimulation, indicating that latent NMDA receptors are recruited. Altogether, these findings indicate the existence of a powerful system of NMDA receptor-mediated synaptic contacts in SCC input to hippocampal CA1 pyramidal neurons and probably also in reciprocal connections between these neurons, which in the usual preparation are kept latent by activity of A1 receptors. PMID:8618915

  18. Alpha7 Nicotinic Acetylcholine Receptors Play a Predominant Role in the Cholinergic Potentiation of N-Methyl-D-Aspartate Evoked Firing Responses of Hippocampal CA1 Pyramidal Cells

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    Zsolt K. Bali

    2017-09-01

    Full Text Available The aim of the present study was to identify in vivo electrophysiological correlates of the interaction between cholinergic and glutamatergic neurotransmission underlying memory. Extracellular spike recordings were performed in the hippocampal CA1 region of anesthetized rats in combination with local microiontophoretic administration of N-methyl-D-aspartate (NMDA and acetylcholine (ACh. Both NMDA and ACh increased the firing rate of the neurons. Furthermore, the simultaneous delivery of NMDA and ACh resulted in a more pronounced excitatory effect that was superadditive over the sum of the two mono-treatment effects and that was explained by cholinergic potentiation of glutamatergic neurotransmission. Next, animals were systemically treated with scopolamine or methyllycaconitine (MLA to assess the contribution of muscarinic ACh receptor (mAChR or α7 nicotinic ACh receptor (nAChR receptor-mediated mechanisms to the observed effects. Scopolamine totally inhibited ACh-evoked firing, and attenuated the firing rate increase evoked by simultaneous application of NMDA and ACh. However, the superadditive nature of the combined effect was preserved. The α7 nAChR antagonist MLA robustly decreased the firing response to simultaneous application of NMDA and ACh, suspending their superadditive effect, without modifying the tonic firing rate increasing effect of ACh. These results provide the first in vivo electrophysiological evidence that, in the hippocampal CA1 region, α7 nAChRs contribute to pyramidal cell activity mainly through potentiation of glutamatergic signaling, while the direct cholinergic modulation of tonic firing is notably mediated by mAChRs. Furthermore, the present findings also reveal cellular physiological correlates of the interplay between cholinergic and glutamatergic agents in behavioral pharmacological models of cognitive decline.

  19. Perampanel inhibition of AMPA receptor currents in cultured hippocampal neurons.

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    Chao-Yin Chen

    Full Text Available Perampanel is an aryl substituted 2-pyridone AMPA receptor antagonist that was recently approved as a treatment for epilepsy. The drug potently inhibits AMPA receptor responses but the mode of block has not been characterized. Here the action of perampanel on AMPA receptors was investigated by whole-cell voltage-clamp recording in cultured rat hippocampal neurons. Perampanel caused a slow (τ∼1 s at 3 µM, concentration-dependent inhibition of AMPA receptor currents evoked by AMPA and kainate. The rates of block and unblock of AMPA receptor currents were 1.5×105 M-1 s-1 and 0.58 s-1, respectively. Perampanel did not affect NMDA receptor currents. The extent of block of non-desensitizing kainate-evoked currents (IC50, 0.56 µM was similar at all kainate concentrations (3-100 µM, demonstrating a noncompetitive blocking action. Parampanel did not alter the trajectory of AMPA evoked currents indicating that it does not influence AMPA receptor desensitization. Perampanel is a selective negative allosteric AMPA receptor antagonist of high-affinity and slow blocking kinetics.

  20. The effects of realistic synaptic distribution and 3D geometry on signal integration and extracellular field generation of hippocampal pyramidal cells and inhibitory neurons

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    Attila I Gulyas

    2016-11-01

    Full Text Available In vivo and in vitro multichannel field and somatic intracellular recordings are frequently used to study mechanisms of network pattern generation. When interpreting these data, neurons are often implicitly considered as electrotonically compact cylinders with a homogeneous distribution of excitatory and inhibitory inputs. However, the actual distributions of dendritic length, diameter, and the densities of excitatory and inhibitory input are non-uniform and cell type-specific. We first review quantitative data on the dendritic structure and synaptic input and output distribution of pyramidal cells and interneurons in the hippocampal CA1 area. Second, using multicompartmental passive models of four different types of neurons, we quantitatively explore the effect of differences in dendritic structure and synaptic distribution on the errors and biases of voltage clamp measurements of inhibitory and excitatory postsynaptic currents. Finally, using the 3-dimensional distribution of dendrites and synaptic inputs we calculate how different inhibitory and excitatory inputs contribute to the generation of local field potential in the hippocampus. We analyze these effects at different realistic background activity levels as synaptic bombardment influences neuronal conductance and thus the propagation of signals in the dendritic tree.We conclude that, since dendrites are electrotonically long and entangled in 3D, somatic intracellular and field potential recordings miss the majority of dendritic events in some cell types, and thus overemphasize the importance of perisomatic inhibitory inputs and belittle the importance of complex dendritic processing. Modeling results also suggest that pyramidal cells and inhibitory neurons probably use different input integration strategies. In pyramidal cells, second- and higher-order thin dendrites are relatively well-isolated from each other, which may support branch-specific local processing as suggested by studies

  1. The neuroprotective effect of topiramate on the ultrastructure of pyramidal neurons of the hippocampal CA1 and CA3 sectors in an experimental model of febrile seizures in rats.

    Science.gov (United States)

    Sobaniec-Lotowska, Maria E; Lotowska, Joanna M

    2011-01-01

    The objective of the current ultrastructural study was to explore the potentiality of the neuroprotective effect of TPM against damage of pyramidal neurons in the hippocampal CA1 and CA3 sectors in an experimental model of febrile seizures (FS) in rats. The FS group exhibited variously pronounced submicroscopic lesions of the neuronal perikarya, including total cell disintegration. Advanced changes induced by hyperthermic stress were manifested by marked degenerative abnormalities, such as substantial swelling of the mitochondria, dilation, degranulation and disintegration of the granular endoplasmic reticulum, and vacuolar changes in the Golgi complex. The most substantially damaged pyramidal neurons showed features of aponecrosis (so-called "dark neurons"), resulting in a marked neuronal loss in the explored areas of the hippocampal cortex. The neurodegenerative changes were accompanied by distinct damage to the blood-brain barrier components. The administration of topiramate at a dose of 80/kg b.m. prior to the induction of hyperthermic stress (as prevention against febrile seizures) caused a substantial neuroprotective action - the drug efficiently lightened the neuronal damage, basically reduced cell aponecrosis and enhanced cell viability. However, TPM applied directly after FS induction did not exert any distinct neuroprotective effect on the perikarya of pyramidal neurons in the hippocampal cortex.

  2. BDNF downregulates 5-HT(2A) receptor protein levels in hippocampal cultures

    DEFF Research Database (Denmark)

    Trajkovska, V; Santini, M A; Marcussen, Anders Bue;

    2009-01-01

    Both brain-derived neurotrophic factor (BDNF) and the serotonin receptor 2A (5-HT(2A)) have been related to depression pathology. Specific 5-HT(2A) receptor changes seen in BDNF conditional mutant mice suggest that BDNF regulates the 5-HT(2A) receptor level. Here we show a direct effect of BDNF...... on 5-HT(2A) receptor protein levels in primary hippocampal neuronal and mature hippocampal organotypic cultures exposed to different BDNF concentrations for either 1, 3, 5 or 7 days. In vivo effects of BDNF on hippocampal 5-HT(2A) receptor levels were further corroborated in (BDNF +/-) mice...... with reduced BDNF levels. In primary neuronal cultures, 7 days exposure to 25 and 50ng/mL BDNF resulted in downregulation of 5-HT(2A), but not of 5-HT(1A), receptor protein levels. The BDNF-associated downregulation of 5-HT(2A) receptor levels was also observed in mature hippocampal organotypic cultures...

  3. Melatonin increases dendritogenesis in the hilus of hippocampal organotypic cultures.

    Science.gov (United States)

    Domínguez-Alonso, Aline; Ramírez-Rodríguez, Gerardo; Benítez-King, Gloria

    2012-05-01

    Neuropsychiatric disorders are characterized by hippocampus decreased volume and loss of dendrite arborizations in the subiculum and prefrontal cortex. These structural changes are associated with diminished memory performance. Hilar neurons of the hippocampus integrate spatial memory and are lost in dementia. They receive information from dentate gyrus neurons through dendrites, while they send axonal tracts to the CA3 region. Dendrites are complex structures of neurons that receive chemical information from presynaptic and postsynaptic terminals. Melatonin, the main product of the pineal gland, has neuroprotective actions through its free radical-scavenging properties and decreases neuronal apoptosis. Recently, we found that melatonin increases dendrite maturation and complexity in new neurons formed in the dentate gyrus of mice. In addition, in N1E-115 cultured cells, the indole stimulates early stages of neurite formation, a process that is known to antecede dendrite formation and maturation. Thus, in this study, we explored whether melatonin stimulates dendrite formation and complexity in the adult rat hippocampus in organotypic slice cultures, which is a model that preserves the hippocampal circuitry and their tridimensional organizations of connectivity. The effects of melatonin were studied in nonpathological conditions and in the absence of harmful agents. The results showed that the indole at nocturnal concentrations reached in the cerebrospinal fluid stimulates dendritogenesis at formation, growth, and maturation stages. Also, data showed that dendrites formed became competent to form presynaptic specializations. Evidence strongly suggests that melatonin may be useful in the treatment of neuropsychiatric diseases to repair the loss of dendrites and re-establish lost synaptic connections.

  4. Low concentrations of the solvent dimethyl sulphoxide alter intrinsic excitability properties of cortical and hippocampal pyramidal cells.

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    Francesco Tamagnini

    Full Text Available Dimethylsulfoxide (DMSO is a widely used solvent in biology. It has many applications perhaps the most common of which is in aiding the preparation of drug solutions from hydrophobic chemical entities. Recent studies have suggested that this molecule may be able to induce apoptosis in neural tissues urging caution regarding its introduction into humans, for example as part of stem cell transplants. Here we have used in vitro electrophysiological methods applied to murine brain slices to examine whether a few hours treatment with 0.05% DMSO (a concentration regarded by many as innocuous alters intrinsic excitability properties of neurones. We investigated pyramidal neurones in two distinct brain regions, namely area CA1 of the hippocampus and layer 2 of perirhinal cortex. In the former there was no effect on resting potential but input resistance was decreased by DMSO pre-treatment. In line with this action potential count for any level of depolarizing current stimulus was reduced by ∼25% following DMSO treatment. Ih-mediated "sag" was also increased in CA1 pyramids and action potential waveform analysis demonstrated that DMSO treatment moved action potential threshold towards resting potential. In perirhinal cortex a decreased action potential output for various depolarizing current stimuli was also seen. In these cells action potential threshold was unaltered by DMSO but a significant increase in action potential width was apparent. These data indicate that pre-treatment with this widely employed solvent can elicit multifaceted neurophysiological changes in mammalian neurones at concentrations below those frequently encountered in the published literature.

  5. Activity-dependent induction of multitransmitter signaling onto pyramidal cells and interneurons of hippocampal area CA3.

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    Romo-Parra, Héctor; Vivar, Carmen; Maqueda, Jasmín; Morales, Miguel A; Gutiérrez, Rafael

    2003-06-01

    The granule cells of the dentate gyrus (DG) are considered to be glutamatergic, but they contain glutamic acid decarboxylase, gamma-amino butyric acid (GABA), and the vesicular GABA transporter mRNA. Their expression is regulated in an activity-dependent manner and coincides with the appearance of GABAergic transmission from the mossy fibers (MF) to pyramidal cells in area CA3. These data support the hypothesis that MF are able to release glutamate and GABA. Following the principle that a given neuron releases the same neurotransmitter(s) onto all its targets, we here demonstrate the emergence, after a generalized convulsive seizure, of MF GABAergic signaling sensitive to activation mGluR-III onto pyramidal cells and interneurons of CA3. Despite this, excitation overrides inhibition in interneurons, preventing disinhibition. Furthermore, on blockade of GABA and glutamate ionotropic receptors, an M1-cholinergic depolarizing signal is also revealed in both targets, which postsynaptically modulates the glutamatergic and GABAergic fast neurotransmission. The emergence of these nonglutamatergic signals depends on protein synthesis. In contrast to cholinergic responses evoked by associational/commissural fibers activation, cholinergic transmission evoked by DG stimulation is only observed after seizures and is strongly depressed by the activation of mGluR-II, whereas both are depressed by M2-AChR activation. With immunohistological experiments, we show that this cholinergic pathway runs parallel to the MF. Thus seizures compromise a delicate balance of excitation and inhibition, on which a complex interaction of different neurotransmitters emerges to counteract excitation at pre- and postsynaptic sites. Particularly, MF GABAergic inhibition emerges to exert an overall inhibitory action on CA3.

  6. The developmental expression of fluorescent proteins in organotypic hippocampal slice cultures from transgenic mice and its use in the determination of excitotoxic neurodegeneration

    DEFF Research Database (Denmark)

    Noraberg, Jens; Jensen, Carsten V; Bonde, Christian

    2007-01-01

    Transgenic mice, expressing fluorescent proteins in neurons and glia, provide new opportunities for real-time microscopic monitoring of degenerative and regenerative structural changes. We have previously validated and compared a number of quantifiable markers for neuronal damage and cell death...... in organotypic brain slice cultures, such as cellular uptake of propidium iodide (PI), loss of microtubule-associated protein 2 (MAP2), Fluoro-Jade (FJ) cell staining, and the release of cytosolic lactate dehydrogenase (LDH). An important supplement to these markers would be data on corresponding morphological...... subpopulations and astroglial cells; and b) examples of excitotoxic, glutamate receptor-induced degeneration of hippocampal CA1 pyramidal cells, with corresponding astroglial reactivity in such cultures. The slice cultures were set up according to standard techniques, by using one-week old pups from four...

  7. A protein phosphatase is involved in the cholinergic suppression of the Ca(2+)-activated K(+) current sI(AHP) in hippocampal pyramidal neurons.

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    Krause, M; Pedarzani, P

    2000-04-27

    The slow calcium-activated potassium current sI(AHP) underlies spike-frequency adaptation and has a substantial impact on the excitability of hippocampal CA1 pyramidal neurons. Among other neuromodulatory substances, sI(AHP) is modulated by acetylcholine acting via muscarinic receptors. The second-messenger systems mediating the suppression of sI(AHP) by muscarinic agonists are largely unknown. Both protein kinase C and A do not seem to be involved, whereas calcium calmodulin kinase II has been shown to take part in the muscarinic action on sI(AHP). We re-examined the mechanism of action of muscarinic agonists on sI(AHP) combining whole-cell recordings with the use of specific inhibitors or activators of putative constituents of the muscarinic pathway. Our results suggest that activation of muscarinic receptors reduces sI(AHP) in a G-protein-mediated and phospholipase C-independent manner. Furthermore, we obtained evidence for the involvement of the cGMP-cGK pathway and of a protein phosphatase in the cholinergic suppression of sI(AHP), whereas release of Ca(2+) from IP(3)-sensitive stores seems to be relevant neither for maintenance nor for modulation of sI(AHP).

  8. Increased proximal bifurcation of CA1 pyramidal apical dendrites in sema3A mutant mice.

    Science.gov (United States)

    Nakamura, Fumio; Ugajin, Kozue; Yamashita, Naoya; Okada, Takako; Uchida, Yutaka; Taniguchi, Masahiko; Ohshima, Toshio; Goshima, Yoshio

    2009-10-10

    Semaphorin-3A (Sema3A) is an attractive guidance molecule for cortical apical dendrites. To elucidate the role of Sema3A in hippocampal dendritic formation, we examined the Sema3A expression pattern in the perinatal hippocampal formation and analyzed hippocampal dendrites of the brains from young adult sema3A mutant mice. Sema3A protein was predominantly expressed in the hippocampal plate and the inner marginal zone at the initial period of apical dendritic growth. Neuropilin-1 and plexin-A, the receptor components for Sema3A, were also localized in the same regions. The Golgi impregnation method revealed that in wildtype mice more than 90% of hippocampal CA1 pyramidal neurons extended a single trunk or apical trunks bifurcated in stratum radiatum. Seven percent of the pyramidal neurons showed proximal bifurcation of apical trunks in stratum pyramidale or at the border of the stratum pyramidale and stratum radiatum. In sema3A mutant mice, proximally bifurcated apical dendrites were increased to 32%, while the single apical dendritic pyramidal neurons were decreased. We designate this phenotype in sema3A mutant mice as "proximal bifurcation." In the dissociated culture system, approximately half of the hippocampal neurons from wildtype mice resembled pyramidal neurons, which possess a long, thick, and tapered dendrite. In contrast, only 30% of the neurons from sema3A mutants exhibited pyramidal-like morphology. Proximal bifurcation of CA1 pyramidal neurons was also increased in the mutant mice of p35, an activator of cyclin-dependent kinase 5 (Cdk5). Thus, Sema3A may facilitate the initial growth of CA1 apical dendrites via the activation of p35/Cdk5, which may in turn signal hippocampal development.

  9. Age- and location-dependent differences in store depletion-induced h-channel plasticity in hippocampal pyramidal neurons.

    Science.gov (United States)

    Clemens, Ann M; Johnston, Daniel

    2014-03-01

    Disruptions of endoplasmic reticulum (ER) Ca(2+) homeostasis are heavily linked to neuronal pathology. Depletion of ER Ca(2+) stores can result in cellular dysfunction and potentially cell death, although adaptive processes exist to aid in survival. We examined the age and region dependence of one postulated, adaptive response to ER store-depletion (SD), hyperpolarization-activated cation-nonspecific (h)-channel plasticity in neurons of the dorsal and ventral hippocampus (DHC and VHC, respectively) from adolescent and adult rats. With the use of whole-cell patch-clamp recordings from the soma and dendrites of CA1 pyramidal neurons, we observed a change in h-sensitive measurements in response to SD, induced by treatment with cyclopiazonic acid, a sarcoplasmic reticulum/ER Ca(2+)-ATPase blocker. We found that whereas DHC and VHC neurons in adolescent animals respond to SD with a perisomatic expression of SD h plasticity, adult animals express SD h plasticity with a dendritic and somatodendritic locus of plasticity in DHC and VHC neurons, respectively. Furthermore, SD h plasticity in adults was dependent on membrane potential and on the activation of L-type voltage-gated Ca(2+) channels. These results suggest that cellular responses to the impairment of ER function, or ER stress, are dependent on brain region and age and that the differential expression of SD h plasticity could provide a neural basis for region- and age-dependent disease vulnerabilities.

  10. Erythropoietin improves synaptic transmission during and following ischemia in rat hippocampal slice cultures.

    Science.gov (United States)

    Weber, Astrid; Maier, Rolf F; Hoffmann, Ulrike; Grips, Martin; Hoppenz, Marc; Aktas, Ayse G; Heinemann, Uwe; Obladen, Michael; Schuchmann, Sebastian

    2002-12-27

    Erythropoietin (EPO) prevents neuronal damage following ischemic, metabolic, and excitotoxic stress. In this study evoked extracellular field potentials (FP) were used to investigate the effect of EPO on synaptic transmission in hippocampal slice cultures. EPO treated cultured slices (40 units/ml for 48 h) showed significantly increased FP during and following oxygen and glucose deprivation compared with untreated control slices. The addition of the Jak2 inhibitor AG490 (50 microM for 48 h) blocked the EPO effect. These data suggest that EPO improves synaptic transmission during and following ischemia in hippocampal slice cultures.

  11. Activation of InsP3 receptors is sufficient for inducing graded intrinsic plasticity in rat hippocampal pyramidal neurons

    Science.gov (United States)

    Ashhad, Sufyan; Johnston, Daniel

    2014-01-01

    The synaptic plasticity literature has focused on establishing necessity and sufficiency as two essential and distinct features in causally relating a signaling molecule to plasticity induction, an approach that has been surprisingly lacking in the intrinsic plasticity literature. In this study, we complemented the recently established necessity of inositol trisphosphate (InsP3) receptors (InsP3R) in a form of intrinsic plasticity by asking if InsP3R activation was sufficient to induce intrinsic plasticity in hippocampal neurons. Specifically, incorporation of d-myo-InsP3 in the recording pipette reduced input resistance, maximal impedance amplitude, and temporal summation but increased resonance frequency, resonance strength, sag ratio, and impedance phase lead. Strikingly, the magnitude of plasticity in all these measurements was dependent on InsP3 concentration, emphasizing the graded dependence of such plasticity on InsP3R activation. Mechanistically, we found that this InsP3-induced plasticity depended on hyperpolarization-activated cyclic nucleotide-gated channels. Moreover, this calcium-dependent form of plasticity was critically reliant on the release of calcium through InsP3Rs, the influx of calcium through N-methyl-d-aspartate receptors and voltage-gated calcium channels, and on the protein kinase A pathway. Our results delineate a causal role for InsP3Rs in graded adaptation of neuronal response dynamics, revealing novel regulatory roles for the endoplasmic reticulum in neural coding and homeostasis. PMID:25552640

  12. Streptozotocin Inhibits Electrophysiological Determinants of Excitatory and Inhibitory Synaptic Transmission in CA1 Pyramidal Neurons of Rat Hippocampal Slices: Reduction of These Effects by Edaravone

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    Ting Ju

    2016-12-01

    Full Text Available Background: Streptozotocin (STZ has served as an agent to generate an Alzheimer's disease (AD model in rats, while edaravone (EDA, a novel free radical scavenger, has recently emerged as an effective treatment for use in vivo and vitro AD models. However, to date, these beneficial effects of EDA have only been clearly demonstrated within STZ-induced animal models of AD and in cell models of AD. A better understanding of the mechanisms of EDA may provide the opportunity for their clinical application in the treatment of AD. Therefore, the purpose of this study was to investigate the underlying mechanisms of STZ and EDA as assessed upon electrophysiological alterations in CA1 pyramidal neurons of rat hippocampal slices. Methods: Through measures of evoked excitatory postsynaptic currents (eEPSCs, AMPAR-mediated eEPSCs (eEPSCsAMPA, evoked inhibitory postsynaptic currents (eIPSCs, evoked excitatory postsynaptic current paired pulse ratio (eEPSC PPR and evoked inhibitory postsynaptic current paired pulse ratio (eIPSC PPR, it was possible to investigate mechanisms as related to the neurotoxicity of STZ and reductions in these effects by EDA. Results: Our results showed that STZ (1000 µM significantly inhibited peak amplitudes of eEPSCs, eEPSCsAMPA and eIPSCs, while EDA (1000 µM attenuated these STZ-induced changes at holding potentials ranging from -60mV to +40 mV for EPSCs and -60mV to +20 mV for IPSCs. Our work also indicated that mean eEPSC PPR were substantially altered by STZ, effects which were partially restored by EDA. In contrast, no significant effects upon eIPSC PPR were obtained in response to STZ and EDA. Conclusion: Our data suggest that STZ inhibits glutamatergic transmission involving pre-synaptic mechanisms and AMPAR, and that STZ inhibits GABAergic transmission by post-synaptic mechanisms within CA1 pyramidal neurons. These effects are attenuated by EDA.

  13. The GABAA receptor agonist THIP is neuroprotective in organotypic hippocampal slice cultures

    DEFF Research Database (Denmark)

    Kristensen, Bjarne Winther; Noraberg, Jens; Zimmer, Jens

    2003-01-01

    interneurons, were examined in hippocampal slice cultures exposed to N-methyl-D-aspartate (NMDA). The NMDA-induced excitotoxicity was quantified by densitometric measurements of propidium iodide (PI) uptake. THIP (100-1000 microM) was neuroprotective in slice cultures co-exposed to NMDA (10 microM) for 48 h...

  14. Kv2 channel regulation of action potential repolarization and firing patterns in superior cervical ganglion neurons and hippocampal CA1 pyramidal neurons.

    Science.gov (United States)

    Liu, Pin W; Bean, Bruce P

    2014-04-02

    Kv2 family "delayed-rectifier" potassium channels are widely expressed in mammalian neurons. Kv2 channels activate relatively slowly and their contribution to action potential repolarization under physiological conditions has been unclear. We explored the function of Kv2 channels using a Kv2-selective blocker, Guangxitoxin-1E (GxTX-1E). Using acutely isolated neurons, mixed voltage-clamp and current-clamp experiments were done at 37°C to study the physiological kinetics of channel gating and action potentials. In both rat superior cervical ganglion (SCG) neurons and mouse hippocampal CA1 pyramidal neurons, 100 nm GxTX-1E produced near-saturating block of a component of current typically constituting ∼60-80% of the total delayed-rectifier current. GxTX-1E also reduced A-type potassium current (IA), but much more weakly. In SCG neurons, 100 nm GxTX-1E broadened spikes and voltage clamp experiments using action potential waveforms showed that Kv2 channels carry ∼55% of the total outward current during action potential repolarization despite activating relatively late in the spike. In CA1 neurons, 100 nm GxTX-1E broadened spikes evoked from -70 mV, but not -80 mV, likely reflecting a greater role of Kv2 when other potassium channels were partially inactivated at -70 mV. In both CA1 and SCG neurons, inhibition of Kv2 channels produced dramatic depolarization of interspike voltages during repetitive firing. In CA1 neurons and some SCG neurons, this was associated with increased initial firing frequency. In all neurons, inhibition of Kv2 channels depressed maintained firing because neurons entered depolarization block more readily. Therefore, Kv2 channels can either decrease or increase neuronal excitability depending on the time scale of excitation.

  15. GABAA receptor-mediated feedforward and feedback inhibition differentially modulate the gain and the neural code transformation in hippocampal CA1 pyramidal cells.

    Science.gov (United States)

    Jang, Hyun Jae; Park, Kyerl; Lee, Jaedong; Kim, Hyuncheol; Han, Kyu Hun; Kwag, Jeehyun

    2015-12-01

    Diverse variety of hippocampal interneurons exists in the CA1 area, which provides either feedforward (FF) or feedback (FB) inhibition to CA1 pyramidal cell (PC). However, how the two different inhibitory network architectures modulate the computational mode of CA1 PC is unknown. By investigating the CA3 PC rate-driven input-output function of CA1 PC using in vitro electrophysiology, in vitro-simulation of inhibitory network, and in silico computational modeling, we demonstrated for the first time that GABAA receptor-mediated FF and FB inhibition differentially modulate the gain, the spike precision, the neural code transformation and the information capacity of CA1 PC. Recruitment of FF inhibition buffered the CA1 PC spikes to theta-frequency regardless of the input frequency, abolishing the gain and making CA1 PC insensitive to its inputs. Instead, temporal variability of the CA1 PC spikes was increased, promoting the rate-to-temporal code transformation to enhance the information capacity of CA1 PC. In contrast, the recruitment of FB inhibition sub-linearly transformed the input rate to spike output rate with high gain and low spike temporal variability, promoting the rate-to-rate code transformation. These results suggest that GABAA receptor-mediated FF and FB inhibitory circuits could serve as network mechanisms for differentially modulating the gain of CA1 PC, allowing CA1 PC to switch between different computational modes using rate and temporal codes ad hoc. Such switch will allow CA1 PC to efficiently respond to spatio-temporally dynamic inputs and expand its computational capacity during different behavioral and neuromodulatory states in vivo.

  16. Antagomirs targeting microRNA-134 increase hippocampal pyramidal neuron spine volume in vivo and protect against pilocarpine-induced status epilepticus.

    Science.gov (United States)

    Jimenez-Mateos, Eva M; Engel, Tobias; Merino-Serrais, Paula; Fernaud-Espinosa, Isabel; Rodriguez-Alvarez, Natalia; Reynolds, James; Reschke, Cristina R; Conroy, Ronan M; McKiernan, Ross C; deFelipe, Javier; Henshall, David C

    2015-07-01

    Emerging data support roles for microRNA (miRNA) in the pathogenesis of various neurologic disorders including epilepsy. MicroRNA-134 (miR-134) is enriched in dendrites of hippocampal neurons, where it negatively regulates spine volume. Recent work identified upregulation of miR-134 in experimental and human epilepsy. Targeting miR-134 in vivo using antagomirs had potent anticonvulsant effects against kainic acid-induced seizures and was associated with a reduction in dendritic spine number. In the present study, we measured dendritic spine volume in mice injected with miR-134-targeting antagomirs and tested effects of the antagomirs on status epilepticus triggered by the cholinergic agonist pilocarpine. Morphometric analysis of over 6,400 dendritic spines in Lucifer yellow-injected CA3 pyramidal neurons revealed increased spine volume in mice given antagomirs compared to controls that received a scrambled sequence. Treatment of mice with miR-134 antagomirs did not alter performance in a behavioral test (novel object location). Status epilepticus induced by pilocarpine was associated with upregulation of miR-134 within the hippocampus of mice. Pretreatment of mice with miR-134 antagomirs reduced the proportion of animals that developed status epilepticus following pilocarpine and increased animal survival. In antagomir-treated mice that did develop status epilepticus, seizure onset was delayed and total seizure power was reduced. These studies provide in vivo evidence that miR-134 regulates spine volume in the hippocampus and validation of the seizure-suppressive effects of miR-134 antagomirs in a model with a different triggering mechanism, indicating broad conservation of anticonvulsant effects.

  17. Preventive effect of piracetam and vinpocetine on hypoxia-reoxygenation induced injury in primary hippocampal culture.

    Science.gov (United States)

    Solanki, P; Prasad, D; Muthuraju, S; Sharma, A K; Singh, S B; Ilavzhagan, G

    2011-04-01

    The present study investigates the potential of Piracetam and Vinpocetine (nootropic drugs, known to possess neuroprotective properties) in preventing hypoxia-reoxygenation induced oxidative stress in primary hippocampal cell culture. The hippocampal culture was exposed to hypoxia (95% N(2), 5% CO(2)) for 3h and followed by 1h of reoxygenation (21% O(2) and 5% CO(2)) at 37 °C. The primary hippocampal cultures were supplemented with the optimum dose of Piracetam and Vinpocetine, independently, and the cultures were divided into six groups, viz. Control/Normoxia, Hypoxia, Hypoxia+Piracetam, Hypoxia+Vinpocetine, Normoxia + Piracetam and Normoxia+Vinpocetine. The cell-viability assays and biochemical oxidative stress parameters were evaluated for each of the six groups. Administration of 1mM Piracetam or 500 nM Vinpocetine significantly prevents the culture from hypoxia-reoxygenation injury when determined by Neutral Red assay, LDH release and Acetylcholine esterase activity. Results showed that Piracetam and Vinpocetine supplementation significantly prevented the fall of mitochondrial membrane potential, rise in ROS generation and reduction in antioxidant levels associated with the hypoxia-reoxygenation injury. In conclusion, the present study establishes that both Piracetam and Vinpocetine give neuroprotection against hypoxia-reoxygenation injury in primary hippocampal cell culture. Copyright © 2010 Elsevier Ltd. All rights reserved.

  18. The Kv2.1 K+ channel targets to the axon initial segment of hippocampal and cortical neurons in culture and in situ

    Directory of Open Access Journals (Sweden)

    Tamkun Michael M

    2008-11-01

    Full Text Available Abstract Background The Kv2.1 delayed-rectifier K+ channel regulates membrane excitability in hippocampal neurons where it targets to dynamic cell surface clusters on the soma and proximal dendrites. In the past, Kv2.1 has been assumed to be absent from the axon initial segment. Results Transfected and endogenous Kv2.1 is now demonstrated to preferentially accumulate within the axon initial segment (AIS over other neurite processes; 87% of 14 DIV hippocampal neurons show endogenous channel concentrated at the AIS relative to the soma and proximal dendrites. In contrast to the localization observed in pyramidal cells, GAD positive inhibitory neurons within the hippocampal cultures did not show AIS targeting. Photoactivable-GFP-Kv2.1-containing clusters at the AIS were stable, moving μm/hr with no channel turnover. Photobleach studies indicated individual channels within the cluster perimeter were highly mobile (FRAP τ = 10.4 ± 4.8 sec, supporting our model that Kv2.1 clusters are formed by the retention of mobile channels behind a diffusion-limiting perimeter. Demonstrating that the AIS targeting is not a tissue culture artifact, Kv2.1 was found in axon initial segments within both the adult rat hippocampal CA1, CA2, and CA3 layers and cortex. Conclusion In summary, Kv2.1 is associated with the axon initial segment both in vitro and in vivo where it may modulate action potential frequency and back propagation. Since transfected Kv2.1 initially localizes to the AIS before appearing on the soma, it is likely multiple mechanisms regulate Kv2.1 trafficking to the cell surface.

  19. Neuroprotective effect of piperine on primarily cultured hippocampal neurons.

    Science.gov (United States)

    Fu, Min; Sun, Zhao-Hui; Zuo, Huan-Cong

    2010-01-01

    It was previously reported that piperine (PIP) significantly blocks convulsions induced by intracerebroventricular injection of threshold doses of kainate, but had no or only slight effects on convulsions induced by L-glutamate, N-methyl-D-aspartate and guanidinosuccinate. In traditional Chinese medicine, black pepper has been used for epileptic treatment; however, the exact mechanism is still unclear. We reported here in that appropriate concentration of PIP effectively inhibites the synchronized oscillation of intracellular calcium in rat hippocampal neuronal networks and represses spontaneous synaptic activities in terms of spontaneous synaptic currents (SSC) and spontaneous excitatory postsynaptic currents (sEPSC). Moreover, pretreatment with PIP expects protective effect on glutamate-induced decrease of cell viability and apoptosis of hippocampal neurons. These data suggest that the neuroprotective effects of PIP might be associated with suppression of synchronization of neuronal networks, presynaptic glutamic acid release, and Ca(2+) overloading.

  20. Neuroprotective effects of anticonvulsants in rat hippocampal slice cultures exposed to oxygen/glucose deprivation

    DEFF Research Database (Denmark)

    Rekling, Jens C

    2003-01-01

    Some anticonvulsants show neuroprotective effects, and may be of use in reducing neuronal death resulting from stroke or traumatic brain injury. Here I report that a broad range of anticonvulsants protect cells in hippocampal slice cultures from death induced by oxygen/glucose deprivation (OGD...

  1. Biocompatibility of silicon-based arrays of electrodes coupled to organotypic hippocampal brain slice cultures

    DEFF Research Database (Denmark)

    Kristensen, Bjarne Winther; Noraberg, J; Thiébaud, P

    2001-01-01

    In this study we examined the passive biocompatibility of a three-dimensional microelectrode array (MEA), designed to be coupled to organotypic brain slice cultures for multisite recording of electrophysiological signals. Hippocampal (and corticostriatal) brain slices from 1-week-old (and newborn...

  2. Effects of GSM 1800 MHz on dendritic development of cultured hippo-campal neurons

    Institute of Scientific and Technical Information of China (English)

    Wei NING; Shu-jun XU; Huai CHIANG; Zheng-ping XU; Su-ya ZHOU; Wei YANG; Jian-hong LUO

    2007-01-01

    Aim: To evaluate the effects of global system for mobile communications (GSM)1800 MHz microwaves on dendritic filopodia, dendritic arborization, and spine maturation during development in cultured hippocampal neurons in rats. Methods: The cultured hippocampal neurons were exposed to GSM 1800 MHz microwaves with 2.4 and 0.8 W/kg, respectively, for 15 min each day from 6 days in vitro (DIV6) to DIV14. The subtle structures of dendrites were displayed by transfection with farnesylated enhanced green fluorescent protein (F-GFP) and GFP-actin on DIV5 into the hippocampal neurons. Results: There was a significant decrease in the density and mobility of dendritic filopodia at DIV8 and in the density of mature spines at DIV14 in the neurons exposed to GSM 1800 MHz microwaves with 2.4 W/kg. In addition, the average length of dendrites per neuron at DIV10 and DIV14 was decreased, while the dendritic arborization was unaltered in these neurons. However, there were no significant changes found in the neurons ex- posed to the GSM 1800 MHz microwaves with 0.8 W/kg. Conclusion: These data indicate that the chronic exposure to 2.4 W/kg GSM 1800 MHz micro- waves during the early developmental stage may affect dendritic development and the formation of excitatory synapses of hippocampal neurons in culture.

  3. Batroxobin Against Anoxic Damage of Rat Hippocampal Neurons in Culture: Morphological Changes and Hsp70 Expression

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@Batroxobin,the thrombin-like enzyme,is used for therapeutic defibrination. We have found that batroxobin has good therapeutic effect in ischemic reperfusion rats and clinical practices in vivo. But we have not studied the neuroprotective effect of batroxobin on anoxic hippocampal neurons in vitro. The purpose of this study was to obtain further information on the mechanism of the batroxobin-induced neuroprotection and examine the neuroprotective effect on neurons exposed to anoxia. The effect of batroxobin on anoxic damages in cultured hippocampal neurons of neonatal rats was investigated by using morphological changes and heat shock protein 70Kd (Hsp70) immunoreactive expression as indicators. The results indicate that batroxobin, besides its defibrination, may have a direct neuroprotective effect on anoxic damage of hippocampal neurons.

  4. Roles of HIF-1α, VEGF, and NF-κB in Ischemic Preconditioning-Mediated Neuroprotection of Hippocampal CA1 Pyramidal Neurons Against a Subsequent Transient Cerebral Ischemia.

    Science.gov (United States)

    Lee, Jae-Chul; Tae, Hyun-Jin; Kim, In Hye; Cho, Jeong Hwi; Lee, Tae-Kyeong; Park, Joon Ha; Ahn, Ji Hyeon; Choi, Soo Young; Bai, Hui Chen; Shin, Bich-Na; Cho, Geum-Sil; Kim, Dae Won; Kang, Il Jun; Kwon, Young-Guen; Kim, Young-Myeong; Won, Moo-Ho; Bae, Eun Joo

    2016-10-26

    Ischemic preconditioning (IPC) provides neuroprotection against subsequent severe ischemic insults by specific mechanisms. We tested the hypothesis that IPC attenuates post-ischemic neuronal death in the gerbil hippocampal CA1 region (CA1) throughout hypoxia inducible factor-1α (HIF-1α) and its associated factors such as vascular endothelial growth factor (VEGF) and nuclear factor-kappa B (NF-κB). Lethal ischemia (LI) without IPC increased expressions of HIF-1α, VEGF, and p-IκB-α (/and translocation of NF-κB p65 into nucleus) in CA1 pyramidal neurons at 12 h and/or 1-day post-LI; thereafter, their expressions were decreased in the CA1 pyramidal neurons with time and newly expressed in non-pyramidal cells (pericytes), and the CA1 pyramidal neurons were dead at 5-day post-LI, and, at this point in time, their immunoreactivities were newly expressed in pericytes. In animals with IPC subjected to LI (IPC/LI)-group), CA1 pyramidal neurons were well protected, and expressions of HIF-1α, VEGF, and p-IκB-α (/and translocation of NF-κB p65 into nucleus) were significantly increased compared to the sham-group and maintained after LI. Whereas, treatment with 2ME2 (a HIF-1α inhibitor) into the IPC/LI-group did not preserve the IPC-mediated increases of HIF-1α, VEGF, and p-IκB-α (/and translocation of NF-κB p65 into nucleus) expressions and did not show IPC-mediated neuroprotection. In brief, IPC protected CA1 pyramidal neurons from LI by upregulation of HIF-1α, VEGF, and p-IκB-α expressions. This study suggests that IPC increases HIF-1α expression in CA1 pyramidal neurons, which enhances VEGF expression and NF-κB activation and that IPC may be a strategy for a therapeutic intervention of cerebral ischemic injury.

  5. Time window characteristics of cultured rat hippocampal neurons subjected to ischemia and reperfusion

    Institute of Scientific and Technical Information of China (English)

    XU Zhong; XU Ru-xiang; LIU Bao-song; JIANG Xiao-dan; HUANG Tao; DING Lian-shu; YUAN Jun

    2005-01-01

    Objective: To explore cell death and apoptosis in rat hippocampal neurons at different time points after ischemia, hypoxia and reperfusion injury and to elucidate time window characteristics in ischemia neuronal injury.Methods: Hippocampal neurons were obtained from rat embryo and were cultured in vitro. The ischemia and reperfusion of cultured rat hippocampal neurons were simulated by oxygen-glucose deprivation (OGD) and recovery. OGD at different time points (0.25 h to 3.0 h) and then the same recovery (24 h) were prepared. Annexin V-PI staining and flow cytometry examined neuron death and apoptosis at different time after injury. Results: After OGD and recovery, both necrosis and apoptosis were observed. At different times after OGD, there were statistically significant differences in neuron necrosis rate (P0.05). At recovery, survival rate of hippocampal neurons further decreased while apoptosis rate increased. Furthermore, apoptosis rates of different time differed greatly (P<0.05). Apoptosis rate gradually increased with significant difference among those of different time points (P<0.05). However, 2 h after ischemia, apoptosis rate decreased markedly.Conclusions: Apoptosis is an important pathway of delayed neuron death. The therapeutic time window should be within 2 h after cerebral ischemia and hypoxia.

  6. Achyranthes bidentata Blume extract promotes neuronal growth in cultured embryonic rat hippocampal neurons

    Institute of Scientific and Technical Information of China (English)

    Xin Tang; Yiren Chen; Xiaosong Gu; Fei Ding

    2009-01-01

    We have prepared an aqueous extract of Achyranthes bidentata Blume,a commonly prescribed Chinese medicinal herb,and reported,in previous studies,that A.bidentata extract benefits nerve growth and prevents neuron apoptosis.In this study,we investigated the actions of ,4.bidentata extract on survival and growth of primarily cultured rat hippocampal neurons.The morphological observation revealed that neurite growth from hippocampal neurons was significantly enhanced by A.bidentata extract with similar effects to those induced by nerve growth factor (NGF),and the greatest neurite growth appeared on treatment with A.bidentata extract at 1 ttg/ml for 24 h.DNA microarray analysis indicated that there were 25 upregulated genes and 47 downregulated genes exhibiting significantly differential expression in hippocampal neurons treated with A.bidentata extract at 1 μg/ml for 6 h when compared to those in untreated hippocampal neurons.Real-time quantitative RT-PCR and Western blot analysis demonstrated that the expression of growth-associated protein-43 in hippocampal neurons was upregulated at both mRNA and protein levels after treatment with A.bidentata extract,and the optimal dosage of the extract was also 1 μg/ml.These data confirm that A.bidentata extract could promote in vitro hippocampal neuronal growth in a dose- and time-dependent manner.(C) 2009 National Natural Science Foundation of China and Chinese Academy of Sciences.Published by Elsevier Limited and Science in China Press.All rights reserved.

  7. Quantitative measurement of neuronal degeneration in organotypic hippocampal cultures after combined oxygen/glucose deprivation.

    Science.gov (United States)

    Strasser, U; Fischer, G

    1995-04-01

    Organotypic hippocampal cultures were used to study cell degeneration during the recovery period after defined periods (30 and 60 min) of combined oxygen/glucose deprivation mimicking transient ischemic conditions. Staining with the fluorescent dye propidium iodide allowed detection of damaged cells. Fluorescence intensity was measured by an image analysis system and used to quantify cell damage at different time points during the recovery period (up to 22 h). At 30 min of oxygen/glucose deprivation cells in the CA1 area were relatively more sensitive compared to CA3 and dentate gyrus cells, with respect to the time course of degeneration and the percentage of affected cells. Expanding the oxygen/glucose deprivation period from 30 to 60 min drastically increased the percentage of cells dying in all hippocampal areas. Still, however, cells in CA1 degenerated faster compared to those in the CA3 area and dentate gyrus. A histological analysis of toluidine blue as well as MAP2-immunostained sections revealed that almost all neurons degenerated in all hippocampal areas following the 60-min deprivation period, whereas GFAP-stained astrocytes appeared to be unaffected. Therefore, neuronal degeneration could be quantified by taking the fluorescence intensity values 22 h after 60 min of oxygen/glucose deprivation as 100% neuronal damage. The possibility to quantify neuronal damage in organotypic cultures offers a useful tool for detailed studies on mechanisms of neuronal cell death in a cell culture system which is closer to in situ conditions than monolayer cell cultures.

  8. Excitatory and inhibitory pathways modulate kainate excitotoxicity in hippocampal slice cultures

    DEFF Research Database (Denmark)

    Casaccia-Bonnefil, P; Benedikz, Eirikur; Rai, R;

    1993-01-01

    In organotypic hippocampal slice cultures, kainate (KA) specifically induces cell loss in the CA3 region while N-methyl-D-aspartate induces cell loss in the CA1 region. The sensitivity of slice cultures to KA toxicity appears only after 2 weeks in vitro which parallels the appearance of mossy...... fibers. KA toxicity is potentiated by co-application with the GABA-A antagonist, picrotoxin. These data suggest that the excitotoxicity of KA in slice cultures is modulated by both excitatory and inhibitory synapses....

  9. A simplified micropatterning method for straight-line neurite extension of cultured hippocampal neurons.

    Science.gov (United States)

    Suzuki, Ikuro; Nakamura, Kosuke; Odawara, Aoi; Alhebshi, Amani; Gotoh, Masao

    2013-01-01

    We report a simplified micropatterning method for the straight-line extension of the neurites of cultured neurons. We prepared a poly-D-lysine (PDL)-patterned surface using a polydimethylsiloxane microfluidic stamp. Hippocampal neurons were cultured on the PDL-bound substrate with the stamp removed, allowing for conventional cell seeding and detailed optical observation without fluorescent label. Cultured neurons elongated neurites along straight lines at the single-cell level and displayed spontaneous firing as detected by time-lapse imaging and Ca(2+) imaging.

  10. Enhanced mossy fiber sprouting and synapse formation in organotypic hippocampal cultures following transient domoic acid excitotoxicity.

    Science.gov (United States)

    Pérez-Gómez, Anabel; Tasker, R Andrew

    2014-05-01

    We have previously reported evidence of BDNF upregulation and increased neurogenesis in rat organotypic hippocampal slice cultures (OHSC) after a transient excitotoxic injury to the hippocampal CA1 area induced by low concentrations of the AMPA/kainate receptor agonist domoic acid (DOM). The changes observed in OHSC were consistent with observations in vivo, where low concentrations of DOM administered to rats during perinatal development caused increased BDNF and TrkB expression in the resulting adult animals. The in vivo low dose-DOM treatment also results in permanent alterations in hippocampal structure and function, including abnormal formation of dentate granule cell axons projecting to area CA3 (mossy fiber sprouting). Our objective in the current study is to determine if low concentrations of DOM induce mossy fiber sprouting and/or synaptogenesis in OHSC in order to facilitate future studies on the mechanisms of structural hippocampal plasticity induced by DOM. We report herein that application of a low concentration of DOM (2 μM) for 24 h followed by recovery induced a significant increase in the expression of the mossy fiber marker ZnT3 that progressed over time in culture. The DOM insult (2 μM, 24 h) also resulted in a significant upregulation of both the presynaptic marker synaptophysin and the postsynaptic marker PSD-95. All of the observed effects were fully antagonized by co-administration of the AMPA/kainate antagonists CNQX or NBQX but only partly by the NMDA antagonist CPP and not by the calcium channel blocker nifedipine. We conclude that exposure of OHSC to concentrations of DOM below those required to induce permanent neurotoxicity can induce a progressive change in hippocampal structure that can effectively model DOM effects in vivo.

  11. Mesenchymal stem cells enhance GABAergic transmission in co-cultured hippocampal neurons.

    Science.gov (United States)

    Mauri, Mario; Lentini, Daniela; Gravati, Marta; Foudah, Dana; Biella, Gerardo; Costa, Barbara; Toselli, Mauro; Parenti, Marco; Coco, Silvia

    2012-04-01

    Bone marrow-derived mesenchymal stem cells (MSCs) are multipotent stem cells endowed with neurotrophic potential combined with immunological properties, making them a promising therapeutic tool for neurodegenerative disorders. However, the mechanisms through which MSCs promote the neurological recovery following injury or inflammation are still largely unknown, although cell replacement and paracrine mechanisms have been hypothesized. In order to find out what are the mechanisms of the trophic action of MSCs, as compared to glial cells, on CNS neurons, we set up a co-culture system where rat MSCs (or cortical astrocytes) were used as a feeding layer for hippocampal neurons without any direct contact between the two cell types. The analysis of hippocampal synaptogenesis, synaptic vesicle recycling and electrical activity show that MSCs were capable to support morphological and functional neuronal differentiation. The proliferation of hippocampal glial cells induced by the release of bioactive substance(s) from MSCs was necessary for neuronal survival. Furthermore, MSCs selectively increased hippocampal GABAergic pre-synapses. This effect was paralleled with a higher expression of the potassium/chloride KCC2 co-transporter and increased frequency and amplitude of mIPSCs and sIPSCs. The enhancement of GABA synapses was impaired by the treatment with K252a, a Trk/neurotrophin receptor blocker, and by TrkB receptor bodies hence suggesting the involvement of BDNF as a mediator of such effects. The results obtained here indicate that MSC-secreted factors induce glial-dependent neuronal survival and trigger an augmented GABAergic transmission in hippocampal cultures, highlighting a new effect by which MSCs could promote CNS repair. Our results suggest that MSCs may be useful in those neurological disorders characterized by an impairment of excitation versus inhibition balance.

  12. S-Nitrosoglutathione and glutathione act as NMDA receptor agonists in cultured hippocampal neurons

    Institute of Scientific and Technical Information of China (English)

    Ting-yu CHIN; Sheau-huei CHUEH; Pao-luh TAO

    2006-01-01

    Aim: To characterize the effect of combined pre- and postnatal morphine exposure on Af-methyl-D-aspartate receptor (NMDA) receptor signaling in hippocampal neurons of the offspring of morphine-addicted female rats. Methods: Cultured hippocampal neurons and synaptosomes were prepared from neonatal and 2-week-old offspring, respectively, of control or morphine-addicted female rats. The increase in the cytosolic Ca2+ concentration ([Ca2+]i) of cultured cells was measured using Fura-2, and glutamate release from synaptosomes was measured enzymatically. Results: Both glutamate and NMDA caused a dose-dependent increase in the [Ca2+]i. The nitric oxide (NO) donor, S-nitrosoglutathione (GSNO), but not 3-morpholinosydnonimine, sodium nitroprusside, and S-nitroso-N-acetylpenicillamine, also induced a [Ca2+]i increase. GSNO and glutathione caused a dose-dependent increase in the [Ca2+]i with respective EC50 values of 56 and 414 μmol/L. Both effects were inhibited by Mg2+ or an NMDA receptor antagonist and were unaffected by the presence of a glutamate scavenger. The other glutathione derivatives, oxidized glutathione, S-methylglutathione, S-ethylglutathione, S-propylglutathione, and S-butylglutathione, the dipeptides, Glu-Cys and Cys-Gly, and the antioxidants, dithiothreitol and mercaptoethanol, failed to induce a [Ca2+]i increase. In addition, glutathione caused a dose-dependent increase in glutamate release from synaptosomes. The maximal responses and the EC50 values for the glutamate-, NMDA-, GSNO-, and glutathione-induced [Ca2+]i increases and the glutathione-induced glutamate release were indistinguishable in the neurons of the offspring from control and morphine-addicted female rats. Conclusion: GSNO and glutathione act as NMDA receptor agonists and, in contrast to hippocampal brain slice, combined pre- and postnatal morphine exposure does not modulate NMDA receptor signaling in the cultured hippocampal neurons.

  13. Colchicine induces apoptosis in organotypic hippocampal slice cultures

    DEFF Research Database (Denmark)

    Kristensen, Bjarne W; Noer, Helle; Gramsbergen, Jan Bert;

    2003-01-01

    with the colchicine-induced apoptosis in 1-week-old cultures showed that colchicine-induced PI uptake and formation of apoptotic nuclei were temporarily prevented by coapplication of the protein synthesis inhibitor cycloheximide. Application of the pancaspase inhibitor z-VAD-fmk almost completely abolished...

  14. Trimethyltin (TMT) neurotoxicity in organotypic rat hippocampal slice cultures

    DEFF Research Database (Denmark)

    Noraberg, J; Gramsbergen, J B; Fonnum, F

    1998-01-01

    ) propidium iodide (PI) uptake, (b) lactate dehydrogenase (LDH) efflux into the culture medium, (c) cellular cobalt uptake as an index of calcium influx, (d) ordinary Nissl cell staining, and (e) immunohistochemical staining for microtubule-associated protein 2 (MAP-2). Cellular degeneration as assessed...

  15. 3-nitropropionic acid neurotoxicity in hippocampal slice cultures

    DEFF Research Database (Denmark)

    Noer, Helle; Kristensen, Bjarne W; Noraberg, Jens

    2002-01-01

    iodide (PI) uptake and lactate dehydrogenase (LDH) efflux into the medium revealed time- and dose-dependent cell death by 3-NP, with EC(50) values of about 60 microM in high or normal glucose. Regional vulnerability, as assessed by PI uptake and MAP2 immunostaining, in 3-week-old cultures was as follows...

  16. Mitochondrial calcium ion and membrane potential transients follow the pattern of epileptiform discharges in hippocampal slice cultures.

    Science.gov (United States)

    Kovács, Richard; Kardos, Julianna; Heinemann, Uwe; Kann, Oliver

    2005-04-27

    Emerging evidence suggests that mitochondrial dysfunction contributes to the pathophysiology of epilepsy. Recurrent mitochondrial Ca2+ ion load during seizures might act on mitochondrial membrane potential (DeltaPsim) and proton motive force. By using electrophysiology and confocal laser-scanning microscopy, we investigated the effects of epileptiform activity, as induced by low-Mg2+ ion perfusion in hippocampal slice cultures, on changes in DeltaPsim and in mitochondrial Ca2+ ion concentration ([Ca2+]m). The mitochondrial compartment was identified by monitoring DeltaPsim in the soma and dendrites of patched CA3 pyramidal cells using the mitochondria-specific voltage-sensitive dye rhodamine-123 (Rh-123). Interictal activity was accompanied by localized mitochondrial depolarization that was restricted to a few mitochondria in small dendrites. In contrast, robust Rh-123 release into the cytosol was observed during seizure-like events (SLEs), indicating simultaneous depolarization of mitochondria. This was critically dependent on Ca2+ ion uptake and extrusion, because inhibition of the mitochondrial Ca2+ ion uniporter by Ru360 and the mitochondrial Na+/Ca2+ ion exchanger by 7-chloro-5-(2-chlorophenyl)-1,5-dihydro-4,1-benzothiazepin-2(3H)-one but not the inhibitor of mitochondrial permeability transition pore, cyclosporin A, decreased the SLE-associated mitochondrial depolarization. The Ca2+ ion dependence of simultaneous mitochondrial depolarization suggested enhanced Ca2+ ion cycling across mitochondrial membranes during epileptiform activity. Indeed, [Ca2+]m fluctuated during interictal activity in single dendrites, and these fluctuations spread over the entire mitochondrial compartment during SLEs, as revealed using mitochondria-specific dyes (rhod-2 and rhod-ff) and spatial frequency-based image analysis. These findings strengthen the hypothesis that epileptic activity results in Ca2+ ion-dependent changes in mitochondrial function that might contribute to the

  17. GDNF and neublastin protect against NMDA-induced excitotoxicity in hippocampal slice cultures

    DEFF Research Database (Denmark)

    Bonde, C; Kristensen, B W; Blaabjerg, M;

    2000-01-01

    The potential neuroprotective effects of glial cell line-derived neurotrophic factor (GDNF) and neublastin (NBN) against NMDA-induced excitotoxicity were examined in hippocampal brain slice cultures. Recombinant human GDNF (25-100 ng/ ml) or NBN, in medium conditioned by growth of transfected, NBN......-producing HiB5 cells, were added to slice cultures I h before exposure to 10 microM NMDA for 48h. Neuronal cell death was monitored, before and during the NMDA exposure, by densitometric measurements of propidium iodide (PI) uptake and loss of Nissl staining. Both the addition of rhGDNF and NBN...

  18. Differential expression of TRPM2 and TRPV4 channels and their potential role in oxidative stress-induced cell death in organotypic hippocampal culture.

    Science.gov (United States)

    Bai, Ji-Zhong; Lipski, Janusz

    2010-03-01

    TRPM2 and TPPV4 channels, two members of TRP channel family, are known to be widely expressed in the brain but their exact expression pattern and function are not well understood. Due to their high Ca(2+) permeability and gating by reactive oxygen species (TRPM2), or cell swelling, low pH and high temperature (TRPV4), they are likely to be involved in cell damage associated with various brain pathologies. The aim of this study was to investigate the expression of these channels and their potential role in oxidative stress-induced cell damage in organotypic hippocampal slice cultures, a model that retains the complex interaction between neurons and astrocytes. Channel expression was confirmed with RT-PCR and western blotting, while immunocytochemistry demonstrated TRPM2 in CA1-CA3 pyramidal neurons and TRPV4 in astrocytes. Oxidative stress induced by exogenous application of H(2)O(2) (600 microM) caused preferential damage of pyramidal neurons, while oxidative stress evoked with mercaptosuccinate (MCS; 400 microM) or buthionine sulfoximine (BSO; 4 microM) mainly damaged astrocytes, as identified by propidium iodide fluorescence. Antioxidants (Trolox 500 microM; MitoE 2 microM) reduced both neuronal and astrocytic cell death. Blockers of TRPV4 channels (Gd(3+) 500 microM; Ruthenium red 1 microM) increased the viability of astrocytes following MCS or BSO treatments, consistent with the expression pattern of these channels. Blockers of TRPM2 channels clotrimazole (20 microM), N-(p-amylcinnomoyl)anthranilic acid (ACA, 25 microM) or flufenamic acid (FFA, 200 microM) failed to protect pyramidal neurons from damage caused by exogenous H(2)O(2), and increased damage of these neurons caused by MCS and BSO. The differential expression of stress-sensitive TRPM2 and TRPV4 channels in hippocampal neurons and astrocytes that show distinct differences in vulnerability to different forms of oxidative stress suggests the specific involvement of these channels in oxidative stress

  19. PACAP enhances axon outgrowth in cultured hippocampal neurons to a comparable extent as BDNF.

    Directory of Open Access Journals (Sweden)

    Katsuya Ogata

    Full Text Available Pituitary adenylate cyclase-activating polypeptide (PACAP exerts neurotrophic activities including modulation of synaptic plasticity and memory, hippocampal neurogenesis, and neuroprotection, most of which are shared with brain-derived neurotrophic factor (BDNF. Therefore, the aim of this study was to compare morphological effects of PACAP and BDNF on primary cultured hippocampal neurons. At days in vitro (DIV 3, PACAP increased neurite length and number to similar levels by BDNF, but vasoactive intestinal polypeptide showed much lower effects. In addition, PACAP increased axon, but not dendrite, length, and soma size at DIV 3 similarly to BDNF. The PACAP antagonist PACAP6-38 completely blocked the PACAP-induced increase in axon, but not dendrite, length. Interestingly, the BDNF-induced increase in axon length was also inhibited by PACAP6-38, suggesting a mechanism involving PACAP signaling. K252a, a TrkB receptor inhibitor, inhibited axon outgrowth induced by PACAP and BDNF without affecting dendrite length. These results indicate that in primary cultured hippocampal neurons, PACAP shows morphological actions via its cognate receptor PAC1, stimulating neurite length and number, and soma size to a comparable extent as BDNF, and that the increase in total neurite length is ascribed to axon outgrowth.

  20. Identification of mRNA for endocannabinoid biosynthetic enzymes within hippocampal pyramidal cells and CA1 stratum radiatum interneuron subtypes using quantitative real-time polymerase chain reaction.

    Science.gov (United States)

    Merrill, C B; McNeil, M; Williamson, R C; Poole, B R; Nelson, B; Sudweeks, S; Edwards, J G

    2012-08-30

    The hippocampus is required for short-term memory and contains both excitatory pyramidal cells and inhibitory interneurons. These cells exhibit various forms of synaptic plasticity, the mechanism underlying learning and memory. More recently, endocannabinoids were identified to be involved in synaptic plasticity. Our goal was to describe the distribution of endocannabinoid biosynthetic enzymes within CA1 stratum radiatum interneurons and CA3/CA1 pyramidal cells. We extracted mRNA from single interneurons and pyramidal cells and used real-time quantitative polymerase chain reaction (RT-PCR) to detect the presence of 12-lipoxygenase, N-acyl-phosphatidylethanolamine-specific phospholipase D, diacylglycerol lipase α, and type I metabotropic glutamate receptors, all known to be involved in endocannabinoid production and plasticity. We observed that the expression of endocannabinoid biosynthetic enzyme mRNA does occur within interneurons and that it is coexpressed with type I metabotropic glutamate receptors, suggesting interneurons have the potential to produce endocannabinoids. We also identified that CA3 and CA1 pyramidal cells express endocannabinoid biosynthetic enzyme mRNA. Our data provide the first molecular biological evidence for putative endocannabinoid production in interneurons, suggesting their potential ability to regulate endocannabinoid-mediated processes, such as synaptic plasticity.

  1. Comparison of excitotoxic profiles of ATPA, AMPA, KA and NMDA in organotypic hippocampal slice cultures.

    Science.gov (United States)

    Kristensen, B W; Noraberg, J; Zimmer, J

    2001-10-26

    The excitotoxic profiles of (RS)-2-amino-3-(3-hydroxy-5-tert-butylisoxazol-4-yl)propionic acid (ATPA), (RS)-2-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA), kainic acid (KA) and N-methyl-D-aspartate (NMDA) were evaluated using cellular uptake of propidium iodide (PI) as a measure for induced, concentration-dependent neuronal damage in hippocampal slice cultures. ATPA is in low concentrations a new selective agonist of the glutamate receptor subunit GluR5 confined to KA receptors and also in high concentrations an AMPA receptor agonist. The following rank order of estimated EC(50) values was found after 2 days of exposure: AMPA (3.7 mM)>NMDA (11 mM)=KA (13 mM)>ATPA (33 mM). Exposed to 30 microM ATPA, 3 microM AMPA and 10 microM NMDA, CA1 was the most susceptible subfield followed by fascia dentata and CA3. Using 8 microM KA, CA3 was the most susceptible subfield, followed by fascia dentata and CA1. In 100 microM concentrations, all four agonists induced the same, maximal PI uptake in all hippocampal subfields, corresponding to total neuronal degeneration. Using glutamate receptor antagonists, like GYKI 52466, NBQX and MK-801, inhibition data revealed that AMPA excitotoxicity was mediated primarily via AMPA receptors. Similar results were found for a high concentration of ATPA (30 microM). In low GluR5 selective concentrations (0.3-3 microM), ATPA did not induce an increase in PI uptake or a reduction in glutamic acid decarboxylase (GAD) activity of hippocampal interneurons. For KA, the excitotoxicity appeared to be mediated via both KA and AMPA receptors. NMDA receptors were not involved in AMPA-, ATPA- and KA-induced excitotoxicity, nor did NMDA-induced excitotoxicity require activation of AMPA and KA receptors. We conclude that hippocampal slice cultures constitute a feasible test system for evaluation of excitotoxic effects and mechanisms of new (ATPA) and classic (AMPA, KA and NMDA) glutamate receptor agonists. Comparison of concentration

  2. 小鼠海马CA1区锥体神经元树突棘的发育%Dendritic spine development of mouse hippocampal CA1 pyramidal neurons

    Institute of Scientific and Technical Information of China (English)

    刘畅; 范文娟; 程维杰; 左曙光; 邓锦波

    2012-01-01

    Objective To investigate the developmental characteristics of dendritic spines in mouse hippocampal CA1 pyramidal neurons by analysing the spine density and morphological changes. Methods Fifty mice were collected at postnatal days ( P ) 0, 5, 10, 20 and 30, 10 mice for each age. Dil diolistic labeling with gene gun was performed to observe dendritic spines development in mouse hippocampal CA1 pyramidal neurons. High quality labeled neurons were examined and photographed under a confocal microscope, whereas the ultrastructure of spines was observed under a transmission electron microscope. Results Dendritic spines changed their morphology and density with mouse development in response to neuronal activity. The smooth endoplasmic reticulum and spine apparatus in dendritic spines of hippocampal CA1 were observed with electron microscopy analysis, which might be involved in the regulation of plasticity at individual synapses. Conclusion The development of dendritic spines may be closely related to synaptogenesis and the formation of synaptic plasticity.%目的 对小鼠海马CA1区锥体神经元正常发育中树突棘密度及各种形态变化进行分析测定,为深入研究突触发生及突触可塑性提供直接的形态学依据.方法 分别取出生后0、5、10、20及30d 5个年龄段的C57BL/6小鼠各10只,采用基因枪对小鼠海马CA1区锥体神经元树突棘进行亲脂性荧光染料DiI标记,通过激光共焦显微镜对其进行观察分析;同时利用透射电镜技术对树突棘的超微结构进行分析.结果 树突棘的形态、大小及其密度随小鼠发育而变化,成熟树突棘内部存在滑面内质网与棘器,可能参与了突触后膜结合蛋白及其转运体的合成.结论 树突棘的发育过程与突触连接的形成以及突触可塑性密切相关.

  3. Concentration-dependent effects of fullerenol on cultured hippocampal neuron viability

    Directory of Open Access Journals (Sweden)

    Zha YY

    2012-06-01

    Full Text Available Ying-ying Zha,1 Bo Yang,1 Ming-liang Tang,2 Qiu-chen Guo,1 Ju-tao Chen,1 Long-ping Wen,3 Ming Wang11CAS Key Laboratory of Brain Function and Disease, School of Life Sciences, University of Science and Technology of China, Hefei, 2Suzhou Institute of NanoTech and NanoBionics, Chinese Academy of Sciences, Suzhou, 3Laboratory of Nano-biology, School of Life Sciences, University of Science and Technology of China, Hefei, People's Republic of ChinaBackground: Recent studies have shown that the biological actions and toxicity of the water-soluble compound, polyhydroxyfullerene (fullerenol, are related to the concentrations present at a particular site of action. This study investigated the effects of different concentrations of fullerenol on cultured rat hippocampal neurons.Methods and results: Fullerenol at low concentrations significantly enhanced hippocampal neuron viability as tested by MTT assay and Hoechst 33342/propidium iodide double stain detection. At high concentrations, fullerenol induced apoptosis confirmed by Comet assay and assessment of caspase proteins.Conclusion: These findings suggest that fullerenol promotes cell death and protects against cell damage, depending on the concentration present. The concentration-dependent effects of fullerenol were mainly due to its influence on the reduction-oxidation pathway.Keywords: fullerenol, nanomaterial, neurotoxicity, neuroprotection, hippocampal neuron

  4. Chelation of hippocampal zinc enhances long-term potentiation and synaptic tagging/capture in CA1 pyramidal neurons of aged rats: implications to aging and memory.

    Science.gov (United States)

    Shetty, Mahesh Shivarama; Sharma, Mahima; Sajikumar, Sreedharan

    2017-02-01

    Aging is associated with decline in cognitive functions, prominently in the memory consolidation and association capabilities. Hippocampus plays a crucial role in the formation and maintenance of long-term associative memories, and a significant body of evidence shows that impairments in hippocampal function correlate with aging-related memory loss. A number of studies have implicated alterations in hippocampal synaptic plasticity, such as long-term potentiation (LTP), in age-related cognitive decline although exact mechanisms underlying are not completely clear. Zinc deficiency and the resultant adverse effects on cognition have been well studied. However, the role of excess of zinc in synaptic plasticity, especially in aging, is not addressed well. Here, we have investigated the hippocampal zinc levels and the impairments in synaptic plasticity, such as LTP and synaptic tagging and capture (STC), in the CA1 region of acute hippocampal slices from 82- to 84-week-old male Wistar rats. We report increased zinc levels in the hippocampus of aged rats and also deficits in the tetani-induced and dopaminergic agonist-induced late-LTP and STC. The observed deficits in synaptic plasticity were restored upon chelation of zinc using a cell-permeable chelator. These data suggest that functional plasticity and associativity can be successfully established in aged neural networks by chelating zinc with cell-permeable chelating agents. © 2016 The Authors. Aging Cell published by the Anatomical Society and John Wiley & Sons Ltd.

  5. Effects of inorganic lead on the differentiation and growth of cultured hippocampal and neuroblastoma cells.

    Science.gov (United States)

    Audesirk, T; Audesirk, G; Ferguson, C; Shugarts, D

    1991-01-01

    Lead exposure has devastating effects on the developing nervous system, and has been implicated in variety of behavioral and cognitive deficits as well as neural morphological abnormalities. Since lead impacts many calcium-dependent processes, one likely mechanism of lead toxicity is its disruption of calcium dependent processes, among which is neuronal differentiation. We investigated the effects of inorganic lead on survival and several parameters of differentiation of cultured neurons. Three different cell types were used: Rat hippocampal neurons (a primary CNS cell type), B50 rat neuroblastoma cells (a transformed CNS-derived cell line), and N1E-115 mouse neuroblastoma cells (a transformed peripherally-derived cell line). Lead concentrations ranged from low nM to 1 mM. Lead effects differed considerably among the three cell types, with B50 cells least affected. Lead effects were generally multimodal, with fewest effects observed at intermediate concentrations. Lead inhibited neurite initiation in hippocampal neurons, but stimulated initiation in N1E-115 cells. In those cells that differentiated, lead increased dendrite numbers in hippocampal neurons and neurite numbers in N1E-115 cells. Lead exposure increased both the length and the degree of branching of axons in hippocampal neurons and the length of neurites in N1E-115 cells. We hypothesize that lead impacts multiple regulatory processes that influence neuron survival and differentiation, and that its effects show differing dose-dependencies. The differing responses of the different cell types to lead suggests that differentiation may be regulated in different ways by the three types of cells. Alternatively, or additionally, the cell types may differ in their ability to compensate for, sequester, or expel lead.

  6. Novel Nuclear Protein Complexes of Dystrophin 71 Isoforms in Rat Cultured Hippocampal GABAergic and Glutamatergic Neurons.

    Directory of Open Access Journals (Sweden)

    Rafael Rodríguez-Muñoz

    Full Text Available The precise functional role of the dystrophin 71 in neurons is still elusive. Previously, we reported that dystrophin 71d and dystrophin 71f are present in nuclei from cultured neurons. In the present work, we performed a detailed analysis of the intranuclear distribution of dystrophin 71 isoforms (Dp71d and Dp71f, during the temporal course of 7-day postnatal rats hippocampal neurons culture for 1h, 2, 4, 10, 15 and 21 days in vitro (DIV. By immunofluorescence assays, we detected the highest level of nuclear expression of both dystrophin Dp71 isoforms at 10 DIV, during the temporal course of primary culture. Dp71d and Dp71f were detected mainly in bipolar GABAergic (≥60% and multipolar Glutamatergic (≤40% neurons, respectively. We also characterized the existence of two nuclear dystrophin-associated protein complexes (DAPC: dystrophin 71d or dystrophin 71f bound to β-dystroglycan, α1-, β-, α2-dystrobrevins, α-syntrophin, and syntrophin-associated protein nNOS (Dp71d-DAPC or Dp71f-DAPC, respectively, in the hippocampal neurons. Furthermore, both complexes were localized in interchromatin granule cluster structures (nuclear speckles of neuronal nucleoskeleton preparations. The present study evinces that each Dp71's complexes differ slightly in dystrobrevins composition. The results demonstrated that Dp71d-DAPC was mainly localized in bipolar GABAergic and Dp71f-DAPC in multipolar Glutamatergic hippocampal neurons. Taken together, our results show that dystrophin 71d, dystrophin 71f and DAP integrate protein complexes, and both complexes were associated to nuclear speckles structures.

  7. Novel Nuclear Protein Complexes of Dystrophin 71 Isoforms in Rat Cultured Hippocampal GABAergic and Glutamatergic Neurons.

    Science.gov (United States)

    Rodríguez-Muñoz, Rafael; Cárdenas-Aguayo, María Del Carmen; Alemán, Víctor; Osorio, Beatriz; Chávez-González, Oscar; Rendon, Alvaro; Martínez-Rojas, Dalila; Meraz-Ríos, Marco Antonio

    2015-01-01

    The precise functional role of the dystrophin 71 in neurons is still elusive. Previously, we reported that dystrophin 71d and dystrophin 71f are present in nuclei from cultured neurons. In the present work, we performed a detailed analysis of the intranuclear distribution of dystrophin 71 isoforms (Dp71d and Dp71f), during the temporal course of 7-day postnatal rats hippocampal neurons culture for 1h, 2, 4, 10, 15 and 21 days in vitro (DIV). By immunofluorescence assays, we detected the highest level of nuclear expression of both dystrophin Dp71 isoforms at 10 DIV, during the temporal course of primary culture. Dp71d and Dp71f were detected mainly in bipolar GABAergic (≥60%) and multipolar Glutamatergic (≤40%) neurons, respectively. We also characterized the existence of two nuclear dystrophin-associated protein complexes (DAPC): dystrophin 71d or dystrophin 71f bound to β-dystroglycan, α1-, β-, α2-dystrobrevins, α-syntrophin, and syntrophin-associated protein nNOS (Dp71d-DAPC or Dp71f-DAPC, respectively), in the hippocampal neurons. Furthermore, both complexes were localized in interchromatin granule cluster structures (nuclear speckles) of neuronal nucleoskeleton preparations. The present study evinces that each Dp71's complexes differ slightly in dystrobrevins composition. The results demonstrated that Dp71d-DAPC was mainly localized in bipolar GABAergic and Dp71f-DAPC in multipolar Glutamatergic hippocampal neurons. Taken together, our results show that dystrophin 71d, dystrophin 71f and DAP integrate protein complexes, and both complexes were associated to nuclear speckles structures.

  8. Mild hypothermia, but not propofol, is neuroprotective in organotypic hippocampal cultures.

    Science.gov (United States)

    Feiner, John R; Bickler, Philip E; Estrada, Sergio; Donohoe, Paul H; Fahlman, Christian S; Schuyler, Jennifer A

    2005-01-01

    The neuroprotective potency of anesthetics such as propofol compared to mild hypothermia remains undefined. Therefore, we determined whether propofol at two clinically relevant concentrations is as effective as mild hypothermia in preventing delayed neuron death in hippocampal slice cultures (HSC). Survival of neurons was assessed 2 and 3 days after 1 h oxygen and glucose deprivation (OGD) either at 37 degrees C (with or without 10 or 100 microM propofol) or at an average temperature of 35 degrees C during OGD (mild hypothermia). Cell death in CA1, CA3, and dentate neurons in each slice was measured with propidium iodide fluorescence. Mild hypothermia eliminated death in CA1, CA3, and dentate neurons but propofol protected dentate neurons only at a concentration of 10 microM; the more ischemia vulnerable CA1 and CA3 neurons were not protected by either 10 microM or 100 microM propofol. In slice cultures, the toxicity of 100 muM N-methyl-D-aspartate (NMDA), 500 microM glutamate, and 20 microM alpha-amino-5-methyl-4-isoxazole propionic acid (AMPA) was not reduced by 100 microM propofol. Because propofol neuroprotection may involve gamma-aminobutyric acid (GABA)-mediated indirect inhibition of glutamate receptors (GluRs), the effects of propofol on GluR activity (calcium influx induced by GluR agonists) were studied in CA1 neurons in HSC, in isolated CA1 neurons, and in cortical brain slices. Propofol (100 and 200 microM, approximate burst suppression concentrations) decreased glutamate-mediated [Ca2+]i increases (Delta[Ca2+]i) responses by 25%-35% in isolated CA1 neurons and reduced glutamate and NMDA Delta[Ca2+]i in acute and cultured hippocampal slices by 35%-50%. In both CA1 neurons and cortical slices, blocking GABAA receptors with picrotoxin reduced the inhibition of GluRs substantially. We conclude that mild hypothermia, but not propofol, protects CA1 and CA3 neurons in hippocampal slice cultures subjected to oxygen and glucose deprivation. Propofol was not

  9. Organotypic hippocampal slice cultures for studies of brain damage, neuroprotection and neurorepair

    DEFF Research Database (Denmark)

    Noraberg, Jens; Poulsen, Frantz Rom; Blaabjerg, Morten

    2005-01-01

    ), Alzheimer's disease (AD) and epilepsia. Studies of non-excitotoxic neurotoxic compounds and the experimental use of slice cultures in studies of HIV neurotoxicity, traumatic brain injury (TBI) and neurogenesis are included. For cerebral ischemia, experimental models with oxygen-glucose deprivation (OGD......) and exposure to glutamate receptor agonists (excitotoxins) are reviewed. For epilepsia, focus is on induction of seizures with effects on neuronal loss, axonal sprouting and neurogenesis. For Alzheimer's disease, the review centers on the use of beta-amyloid (Abeta) in different models, while the section...... on repair is focused on neurogenesis and cell migration. The culturing techniques, set-up of models, and analytical tools, including markers for neurodegeneration, like the fluorescent dye propidium iodide (PI), are reviewed and discussed. Comparisons are made between hippocampal slice cultures and other...

  10. Long-term live imaging of neuronal circuits in organotypic hippocampal slice cultures.

    Science.gov (United States)

    Gogolla, Nadine; Galimberti, Ivan; DePaola, Vincenzo; Caroni, Pico

    2006-01-01

    This protocol details a method for imaging organotypic slice cultures from the mouse hippocampus. The cultures are based on the interface method, which does not require special equipment, is easy to execute, and yields slice cultures that can be imaged repeatedly after they are isolated on postnatal day 6-9 and for up to 6 months in vitro. The preserved tissue architecture facilitates the analysis of defined hippocampal synapses, cells and entire projections. Time-lapse imaging is based on transgenes expressed in the mice, or on constructs introduced through transfection or viral vectors; it can reveal processes that develop over time periods ranging from seconds to months. Imaging can be repeated at least eight times without detectable morphological damage to neurons. Subsequent to imaging, the slices can be processed for immunocytochemistry or electron microscopy, to collect further information about the structures that have been imaged. This protocol can be completed in 35 min.

  11. Preparation of organotypic hippocampal slice cultures for long-term live imaging.

    Science.gov (United States)

    Gogolla, Nadine; Galimberti, Ivan; DePaola, Vincenzo; Caroni, Pico

    2006-01-01

    This protocol details a method to establish organotypic slice cultures from mouse hippocampus, which can be maintained for several months. The cultures are based on the interface method, which does not require special equipment, is easy to execute and yields slice cultures that can be imaged repeatedly--from when they are isolated at postnatal day 6-9, and up to 6 months in vitro. The preserved tissue architecture facilitates the analysis of defined hippocampal synapses, cells and entire projections. Monitoring of defined cellular and molecular components in the slices can be achieved by preparing slices from transgenic mice or by introducing transgenes through transfection or viral vectors. This protocol can be completed in 3 h.

  12. Prolactin mediates neuroprotection against excitotoxicity in primary cell cultures of hippocampal neurons via its receptor.

    Science.gov (United States)

    Vergara-Castañeda, E; Grattan, D R; Pasantes-Morales, H; Pérez-Domínguez, M; Cabrera-Reyes, E A; Morales, T; Cerbón, M

    2016-04-01

    Recently it has been reported that prolactin (PRL) exerts a neuroprotective effect against excitotoxicity in hippocampus in the rat in vivo models. However, the exact mechanism by which PRL mediates this effect is not completely understood. The aim of our study was to assess whether prolactin exerts neuroprotection against excitotoxicity in an in vitro model using primary cell cultures of hippocampal neurons, and to determine whether this effect is mediated via the prolactin receptor (PRLR). Primary cell cultures of rat hippocampal neurons were used in all experiments, gene expression was evaluated by RT-qPCR, and protein expression was assessed by Western blot analysis and immunocytochemistry. Cell viability was assessed by using the MTT method. The results demonstrated that PRL treatment of neurons from primary cultures did not modify cell viability, but that it exerted a neuroprotective effect, with cells treated with PRL showing a significant increase of viability after glutamate (Glu)--induced excitotoxicity as compared with neurons treated with Glu alone. Cultured neurons expressed mRNA for both PRL and its receptor (PRLR), and both PRL and PRLR expression levels changed after the excitotoxic insult. Interestingly, the PRLR protein was detected as two main isoforms of 100 and 40 kDa as compared with that expressed in hypothalamic cells, which was present only as a 30 kDa variant. On the other hand, PRL was not detected in neuron cultures, either by western blot or by immunohistochemistry. Neuroprotection induced by PRL was significantly blocked by specific oligonucleotides against PRLR, thus suggesting that the PRL role is mediated by its receptor expressed in these neurons. The overall results indicated that PRL induces neuroprotection in neurons from primary cell cultures.

  13. MEK inhibitor PD98059 acutely inhibits synchronized spontaneous Ca2+ oscillations in cultured hippocampal networks

    Institute of Scientific and Technical Information of China (English)

    Yan-fang RUI; Zhao-hui SUN; Jia-ping GU; Zhong-hua SHENG; Xiang-ping HE; Zuo-ping XIE

    2006-01-01

    Aim: To investigate the changes in synchronized spontaneous Ca2+ oscillations induced by mitogen-activated protein kinase kinase (MEK) inhibitor PD98059 at different concentrations in cultured hippocampal network. Methods: Hippocampal neurons in culture for 1-2 weeks were used for this study. Spontaneous synaptic activities of these hippocampal neurons were examined by Ca2+ imaging using calcium-sensitive dye. MEK inhibitor PD98059 (10,30, and 60 μmol/L) and SB202474 (10 and 60 μmol/L), a negative control for mitogen-activated protein kinase (MAPK) cascade study, were applied to the cells under the microscope while imaging was taking place. Results: PD98059 at a lower concentration of 10 μmol/L had little effect on the Ca2+ oscillation. At the higher concentration of 30 μmol/L, 5 min after application of PD98059, the spike frequency was decreased to 25.38%±7.40% (mean±SEM, n=16, F<0.01 vs medium control) of that of the control period. At an even higher concentration of 60 μmol/L, 5 min after application of PD98059, the spike frequency was decreased to 14.53%±5.34% (mean±SEM, n=16, P<0.01 vs medium control) of that of the control period. The spike amplitude underwent a corresponding decrease. However, the negative control SB202474 at concentrations of 10 and 60 μmol/L had little inhibition effect on the Ca2+ oscillation. Conclusion: These results indicate that PD98059 inhibits synchronized spontaneous Ca2+ oscillation through inhibition of MEK, which hints that the MAPK cascade is required to maintain synchronized spontaneous Ca2+ oscillation.

  14. Flat pyramid

    OpenAIRE

    Doherty, Kevin Andrew

    2017-01-01

    'Flat pyramid' is a multi-channel video installation. The project employs appropriated promotional and instructional video from a defunct pyramid scheme as the source material for fictionalized reenactment. The footage primarily consists of presentation documentation, testimonial interviews, and product photography—throughout all of which cutting rarely occurs between takes. Perpetrators and victims are seen moving in and out of their promotional personas, inadvertently making their disquieti...

  15. Kainic acid-induced neurodegeneration and activation of inflammatory processes in organotypic hippocampal slice cultures: treatment with cyclooxygenase-2 inhibitor does not prevent neuronal death.

    Science.gov (United States)

    Järvelä, Juha T; Ruohonen, Saku; Kukko-Lukjanov, Tiina-Kaisa; Plysjuk, Anna; Lopez-Picon, Francisco R; Holopainen, Irma E

    2011-06-01

    In the postnatal rodent hippocampus status epilepticus (SE) leads to age- and region-specific excitotoxic neuronal damage, the precise mechanisms of which are still incompletely known. Recent studies suggest that the activation of inflammatory responses together with glial cell reactivity highly contribute to excitotoxic neuronal damage. However, pharmacological tools to attenuate their activation in the postnatal brain are still poorly elucidated. In this study, we investigated the role of inflammatory mediators in kainic acid (KA)-induced neuronal damage in organotypic hippocampal slice cultures (OHCs). A specific cyclooxygenase-2 (COX-2) inhibitor N-[2-(cyclohexyloxy)-4-nitrophenyl]-methanesulfonamide (NS-398) was used to study whether or not it could ameliorate neuronal death. Our results show that KA treatment (24 h) resulted in a dose-dependent degeneration of CA3a/b pyramidal neurons. Furthermore, COX-2 immunoreactivity was pronouncedly enhanced particularly in CA3c pyramidal neurons, microglial and astrocyte morphology changed from a resting to active appearance, the expression of the microglial specific protein, Iba1, increased, and prostaglandin E₂ (PGE₂) production increased. These indicated the activation of inflammatory processes. However, the expression of neither proinflammatory cytokines, i.e. tumour necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β), nor the anti-inflammatory cytokine IL-10 mRNA was significantly altered by KA treatment as studied by real-time PCR. Despite activation of an array of inflammatory processes, neuronal damage could not be rescued either with the combined pre- and co-treatment with a specific COX-2 inhibitor, NS-398. Our results suggest that KA induces activation of a repertoire of inflammatory processes in immature OHCs, and that the timing of anti-inflammatory treatment to achieve neuroprotection is a challenge due to developmental properties and the complexity of inflammatory processes activated by

  16. Tissue plasminogen activator inhibits NMDA-receptor-mediated increases in calcium levels in cultured hippocampal neurons

    Directory of Open Access Journals (Sweden)

    Samuel D Robinson

    2015-10-01

    Full Text Available NMDA receptors (NMDARs play a critical role in neurotransmission, acting as essential mediators of many forms of synaptic plasticity, and also modulating aspects of development, synaptic transmission and cell death. NMDAR-induced responses are dependent on a range of factors including subunit composition and receptor location. Tissue-type plasminogen activator (tPA is a serine protease that has been reported to interact with NMDARs and modulate NMDAR activity. In this study we report that tPA inhibits NMDAR-mediated changes in intracellular calcium levels in cultures of primary hippocampal neurons stimulated by low (5 μM but not high (50 μM concentrations of NMDA. tPA also inhibited changes in calcium levels stimulated by presynaptic release of glutamate following treatment with bicucculine/4-AP. Inhibition was dependent on the proteolytic activity of tPA but was unaffected by α2-antiplasmin, an inhibitor of the tPA substrate plasmin, and RAP, a pan-ligand blocker of the low-density lipoprotein receptor, two proteins previously reported to modulate NMDAR activity. These findings suggest that tPA can modulate changes in intracellular calcium levels in a subset of NMDARs expressed in cultured embryonic hippocampal neurons through a mechanism that involves the proteolytic activity of tPA and synaptic NMDARs.

  17. BDNF and NT-3 increase velocity of activity front propagation in unidimensional hippocampal cultures.

    Science.gov (United States)

    Jacobi, Shimshon; Soriano, Jordi; Moses, Elisha

    2010-12-01

    Neurotrophins are known to promote synapse development as well as to regulate the efficacy of mature synapses. We have previously reported that in two-dimensional rat hippocampal cultures, brain-derived neurotrophic factor (BDNF) and neurotrophin-3 significantly increase the number of excitatory input connections. Here we measure the effect of these neurotrophic agents on propagating fronts that arise spontaneously in quasi-one-dimensional rat hippocampal cultures. We observe that chronic treatment with BDNF increased the velocity of the propagation front by about 30%. This change is attributed to an increase in the excitatory input connectivity. We analyze the experiment using the Feinerman-Golomb/Ermentrout-Jacobi/Moses-Osan model for the propagation of fronts in a one-dimensional neuronal network with synaptic delay and introduce the synaptic connection probability between adjacent neurons as a new parameter of the model. We conclude that BDNF increases the number of excitatory connections by favoring the probability to form connections between neurons, but without significantly modifying the range of the connections (connectivity footprint).

  18. Mechanism underlying blockade of voltage-gated calcium channels by agmatine in cultured rat hippocampal neurons

    Institute of Scientific and Technical Information of China (English)

    Jian-quan ZHENG; Xie-chuan WENG; Xiao-dan GAI; Jin LI; Wen-bin XIAO

    2004-01-01

    AIM: To investigate whether agmatine could selectively block a given type of the voltage-gated calcium channels (VGCC) and whether related receptors are involved in the blocking effect of agmatine on VGCC. METHODS: The whole-cell patch recording technique was performed to record VGCC currents in the cultured neonatal rat hippocampal neurons. RESULTS: Verapamil (100 μmol/L), a selective blocker of L-type calcium channel, significantly inhibited VGCC current by 80 %± 7 %. Agmatine (100 μmol/L) could further depress the remained currents by 25 %±6 %. The α2-adrenoceptor antagonist yohimbine (10 μmol/L) and the I2 imidazoline receptor antagonist idazoxon (10 and 40 μmol/L) had no significant effect on VGCC currents when used respectively. When the mixture of yohimbine and agmatine was applied, VGCC currents were still depressed remarkably. However, the blocking effect of agmatine was decreased by 29 %± 8 % in the presence of idazoxon (10 μmol/L). The effect of idazoxon did not increase at a higher concentration (40 μmol/L). CONCLUSION: Agmatine could block the L- and other types of VGCC currents in the cultured rat hippocampal neurons. Blocking effect of agmatine on VGCC was partially related to I2 imidazoline receptor and had no relationship with α2-adrenoceptors.

  19. Effect of polybrominated diphenyl ether on development of cultured hippocampal neuron

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Polybrominated diphenyl ether (PBDE) is a persistently environmental pollutant ubiquitously found in wildlife and humans. Although concern on PBDE's toxic effects is steadily increasing, its action on the central nervous system (CNS) remains largely unknown. To address this issue, the present study examined the development inhibition of PBDE in neurons. The primary cultured hippocampal neurons of rat were exposed to the commercial decabromodiphenyl ether (deca-BDE), and the neurite length, bifurcation, and synapse formation and maturation were evaluated, based on the confocal microscope imaging. The results showed that the development inhibition in neurons occurred at 15 μmol/L, indicating that PBDE is a potent neurotoxicant and it might obviously inhibit the development of cultured neurons.

  20. Effect of polybrominated diphenyl ether on development of cultured hippocampal neuron

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Polybrominated diphenyl ether (PBDE) is a persistently environmental pollutant ubiquitously found in wildlife and humans. Although concern on PBDE’s toxic effects is steadily increasing, its action on the central nervous system (CNS) remains largely unknown. To address this issue, the present study ex- amined the development inhibition of PBDE in neurons. The primary cultured hippocampal neurons of rat were exposed to the commercial decabromodiphenyl ether (deca-BDE), and the neurite length, bi- furcation, and synapse formation and maturation were evaluated, based on the confocal microscope imaging. The results showed that the development inhibition in neurons occurred at 15 μmol/L, indi- cating that PBDE is a potent neurotoxicant and it might obviously inhibit the development of cultured neurons.

  1. Dopamine-dependent effects on basal and glutamate stimulated network dynamics in cultured hippocampal neurons.

    Science.gov (United States)

    Li, Yan; Chen, Xin; Dzakpasu, Rhonda; Conant, Katherine

    2017-02-01

    Oscillatory activity occurs in cortical and hippocampal networks with specific frequency ranges thought to be critical to working memory, attention, differentiation of neuronal precursors, and memory trace replay. Synchronized activity within relatively large neuronal populations is influenced by firing and bursting frequency within individual cells, and the latter is modulated by changes in intrinsic membrane excitability and synaptic transmission. Published work suggests that dopamine, a potent modulator of learning and memory, acts on dopamine receptor 1-like dopamine receptors to influence the phosphorylation and trafficking of glutamate receptor subunits, along with long-term potentiation of excitatory synaptic transmission in striatum and prefrontal cortex. Prior studies also suggest that dopamine can influence voltage gated ion channel function and membrane excitability in these regions. Fewer studies have examined dopamine's effect on related endpoints in hippocampus, or potential consequences in terms of network burst dynamics. In this study, we record action potential activity using a microelectrode array system to examine the ability of dopamine to modulate baseline and glutamate-stimulated bursting activity in an in vitro network of cultured murine hippocampal neurons. We show that dopamine stimulates a dopamine type-1 receptor-dependent increase in number of overall bursts within minutes of its application. Notably, however, at the concentration used herein, dopamine did not increase the overall synchrony of bursts between electrodes. Although the number of bursts normalizes by 40 min, bursting in response to a subsequent glutamate challenge is enhanced by dopamine pretreatment. Dopamine-dependent potentiation of glutamate-stimulated bursting was not observed when the two modulators were administered concurrently. In parallel, pretreatment of murine hippocampal cultures with dopamine stimulated lasting increases in the phosphorylation of the

  2. Slow recovery from inactivation of Na+ channels underlies the activity-dependent attenuation of dendritic action potentials in hippocampal CA1 pyramidal neurons.

    Science.gov (United States)

    Colbert, C M; Magee, J C; Hoffman, D A; Johnston, D

    1997-09-01

    Na+ action potentials propagate into the dendrites of pyramidal neurons driving an influx of Ca2+ that seems to be important for associative synaptic plasticity. During repetitive (10-50 Hz) firing, dendritic action potentials display a marked and prolonged voltage-dependent decrease in amplitude. Such a decrease is not apparent in somatic action potentials. We investigated the mechanisms of the different activity dependence of somatic and dendritic action potentials in CA1 pyramidal neurons of adult rats using whole-cell and cell-attached patch-clamp methods. There were three main findings. First, dendritic Na+ currents decreased in amplitude when repeatedly activated by brief (2 msec) depolarizations. Recovery was slow and voltage-dependent. Second, Na+ currents decreased much less in somatic than in dendritic patches. Third, although K+ currents remained constant during trains, K+ currents were necessary for dendritic action potential amplitude to decrease in whole-cell experiments. These results suggest that regional differences in Na+ and K+ channels determine the differences in the activity dependence of somatic and dendritic action potential amplitudes.

  3. Calsyntenin-1 regulates targeting of dendritic NMDA receptors and dendritic spine maturation in CA1 hippocampal pyramidal cells during postnatal development.

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    Ster, Jeanne; Steuble, Martin; Orlando, Clara; Diep, Tu-My; Akhmedov, Alexander; Raineteau, Olivier; Pernet, Vincent; Sonderegger, Peter; Gerber, Urs

    2014-06-25

    Calsyntenin-1 is a transmembrane cargo-docking protein important for kinesin-1-mediated fast transport of membrane-bound organelles that exhibits peak expression levels at postnatal day 7. However, its neuronal function during postnatal development remains unknown. We generated a knock-out mouse to characterize calsyntenin-1 function in juvenile mice. In the absence of calsyntenin-1, synaptic transmission was depressed. To address the mechanism, evoked EPSPs were analyzed revealing a greater proportion of synaptic GluN2B subunit-containing receptors typical for less mature synapses. This imbalance was due to a disruption in calsyntenin-1-mediated dendritic transport of NMDA receptor subunits. As a consequence of increased expression of GluN2B subunits, NMDA receptor-dependent LTP was enhanced at Schaffer collateral-CA1 pyramidal cell synapses. Interestingly, these defects were accompanied by a decrease in dendritic arborization and increased proportions of immature filopodia-like dendritic protrusions at the expense of thin-type dendritic spines in CA1 pyramidal cells. Thus, these results highlight a key role for calsyntenin-1 in the transport of NMDA receptors to synaptic targets, which is necessary for the maturation of neuronal circuits during early development.

  4. Neurotoxicity induced by amyloid beta-peptide and ibotenic acid in organotypic hippocampal cultures: protection by S-allyl-L-cysteine, a garlic compound.

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    Ito, Yoshihisa; Ito, Moriyuki; Takagi, Noritaka; Saito, Hiroshi; Ishige, Kumiko

    2003-09-19

    We have assessed amyloid-beta (Abeta)-induced neurotoxicity, with and without added ibotenic acid (IBO), a potent N-methyl-D-aspartate (NMDA) agonist, in an organotypic hippocampal slice culture (OHC). In the OHC, there was little neurotoxicity after treatment with Abeta(25-35) (25 or 50 microM) alone for 48 h. However, with IBO alone neuronal death was observed in the pyramidal cell layer at low concentrations, and there was dramatic neuronal death at concentrations of 65 microM or more. When Abeta was combined with IBO (Abeta+IBO) there was more intense cell death than with IBO alone. S-Allyl-L-cysteine (SAC), one of the organosulfur compounds having a thioallyl group in aged garlic extract, was shown to protect the hippocampal neurons in the CA3 area and the dentate gyrus (DG) from the cell death induced by Abeta+IBO with no change in the CA1 area. Although L-glutamate (500 microM) potentiated the degree of IBO-induced neuronal death, it attenuated the Abeta+IBO-induced neuronal death in both the CA3 area and the DG with no obvious effect on the CA1 area. These results suggest that Abeta+IBO induces extensive neuronal death, and that SAC and L-glutamate protect cells from death in specific areas of the hippocampus. In addition, inhibition using a pan-caspase inhibitor, z-VAD-fmk, only provided partial protection from Abeta+IBO-induced toxicity for the neurons in the CA3 area. These results suggest that multiple mechanisms may be involved in Abeta+IBO-induced neuronal death in the OHC.

  5. High abundance of BDNF within glutamatergic presynapses of cultured hippocampal neurons

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    Thomas eAndreska

    2014-04-01

    Full Text Available In the mammalian brain, the neurotrophin brain-derived neurotrophic factor (BDNF has emerged as a key factor for synaptic refinement, plasticity and learning. Although BDNF-induced signaling cascades are well known, the spatial aspects of the synaptic BDNF localization remained unclear. Recent data provide strong evidence for an exclusive presynaptic location and anterograde secretion of endogenous BDNF at synapses of the hippocampal circuit. In contrast, various studies using BDNF overexpression in cultured hippocampal neurons support the idea that postsynaptic synapses and other dendritic structures are the preferential sites of BDNF localization and release. In this study we used rigorously tested anti-BDNF antibodies and achieved a dense labeling of endogenous BDNF close to synapses. Confocal microscopy showed natural BDNF close to many, but not all glutamatergic synapses, while neither GABAergic synapses nor postsynaptic structures carried a typical synaptic BDNF label. To visualize the BDNF distribution within the fine structure of synapses, we implemented super resolution fluorescence imaging by direct stochastic optical reconstruction microscopy (dSTORM. Two-color dSTORM images of neurites were acquired with a spatial resolution of ~20 nm. At this resolution, the synaptic scaffold proteins Bassoon and Homer exhibit hallmarks of mature synapses and form juxtaposed bars, separated by a synaptic cleft. BDNF imaging signals form granule-like clusters with a mean size of ~60 nm and are preferentially found within the fine structure of the glutamatergic presynapse. Individual glutamatergic presynapses carried up to 90% of the synaptic BDNF immunoreactivity, and only a minor fraction of BDNF molecules was found close to the postsynaptic bars. Our data proof that hippocampal neurons are able to enrich and store high amounts of BDNF in small granules within the mature glutamatergic presynapse, at a principle site of synaptic plasticity.

  6. Base excision repair activities in organotypic hippocampal slice cultures exposed to oxygen and glucose deprivation.

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    Rolseth, Veslemøy; Rundén-Pran, Elise; Neurauter, Christine Gran; Yndestad, Arne; Luna, Luisa; Aukrust, Pål; Ottersen, Ole Petter; Bjørås, Magnar

    2008-06-01

    The capacity for DNA repair is likely to be one of the factors that determine the vulnerability of neurons to ischemic stress and may influence the pathological outcome of stroke. In this report, initiation of base excision repair (BER) was assessed by analysis of enzyme activity and gene expression level of DNA glycosylases and AP-endonucleases in rat organotypic hippocampal slice cultures exposed to oxygen and glucose deprivation (OGD) - an in vitro model of stroke. Under basal conditions, AP-endonuclease activity and base removal of ethenoadenine and 8-oxoguanine (8-oxoG) were higher (by approximately 20-35 %) in CA3/fascia dentata (FD) than in CA1. Base removal of uracil did not differ between the two hippocampal regions, while removal of 5-hydroxyuracil (5-OHU) was slightly less efficient in CA3/FD than in CA1. Analyses performed immediately after 30 min of OGD revealed a decreased AP-endonuclease activity (by approximately 20%) in CA1 as well as CA3/FD, and an increased ethenoadenine activity (by approximately 25%) in CA1. Activities for 8-oxoG, 5-OHU and uracil showed no significant changes at this time point. At 8h after OGD, none of the enzyme activities differed from control values. Real-time RT-PCR showed that transcription of DNA glycosylases, including Ogg1, Nth1, Ung, Aag, Neil1 and Neil2 were not changed in response to OGD treatment (t=0 h). The hippocampal expression of Neil2 was low compared with the other DNA glycosylases. These data indicate that CA1 has a lower capacity than CA3/FD for removal of base lesions under basal conditions. The relatively low capacity for BER in basal conditions and the apparent failure to upregulate repair of oxidative damage after OGD might contribute to the high vulnerability of CA1 to ischemic injury.

  7. Influence of Ginkgo Biloba extract on beta-secretase in rat hippocampal neuronal cultures following chronic hypoxic and hypoglycemic conditions

    Institute of Scientific and Technical Information of China (English)

    Xueneng Guan; Fuling Yan

    2008-01-01

    BACKGROUND: Preparation of Ginkgo leaf has been widely used to improve cognitive deficits and dementia, in particular in Alzheimer's disease patients. However, the precise mechanism of action of Ginkgo leaf remains unclear.OBJECTIVE: To explore the effect of Ginkgo Biloba extract (Egb761), Ginaton, on β-secretase expression in rat hippocampal neuronal cultures following chronic hypoxic and hypoglycemic conditions.DESIGN, TIME AND SETTNG: Completely by randomized, grouping study. The experiment was performed at the Laboratory of Molecular Imaging, Southeast University between August 2006 and August 2007.MATERIALS: A total of 128 Wistar rats aged 24 hours were selected, and hippocampal neurons were harvested for primary cultures.METHODS: On day 7, primary hippocampal neuronal cultures were treated with Egb761 (0, 25, 50, 100, 150, and 200 μ g/mL) under hypoxic/hypoglycemic or hypoglycemic culture conditions for 12, 24, and 36 hours, respectively. Hippocampal neurons cultured in primary culture medium served as control.MAIN OUTCOME MEASURES: Cell viability was assayed using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT); fluorescence detection of β-secretase activity was performed; Western Blot was used to measure β -secretase expression.RESULTS: Cell viability under hypoxic/hypoglycemic or hypoglycemic culture conditions was significantly less than control cells (P 25 μ g/mL Egb761 induced greater cell viability (P 0.05). Α -secretase activity was increased after 12 hours in hypoxic/hypoglycemic culture (P 0.05). Β -secretase activity was greater after 12, 24, and 36 hours in hypoxic/hypoglycemic culture conditions, compared with control conditions (P < 0.05). Β-secretase activity was significantly decreased in neurons treated with Egb761 for 12, 24, or 36 hours, compared with the hypoxic/hypoglycemic group (P < 0.05).β-secretase protein expression was significantly up-regulated in neurons cultured in hypoxic/hypoglycemic conditions for

  8. Modulation of neurite branching by protein phosphorylation in cultured rat hippocampal neurons.

    Science.gov (United States)

    Audesirk, G; Cabell, L; Kern, M

    1997-09-20

    The control of branching of axons and dendrites is poorly understood. It has been hypothesized that branching may be produced by changes in the cytoskeleton [F.J. Diez-Guerra, J. Avila, MAP2 phosphorylation parallels dendrite arborization in hippocampal neurones in culture, NeuroReport 4 (1993) 412-419; P. Friedrich, A. Aszodi, MAP2: a sensitive cross-linker and adjustable spacer in dendritic architecture, FEBS Lett. 295 (1991) 5-9]. The assembly and stability of microtubules, which are prominent cytoskeletal elements in both axons and dendrites, are regulated by microtubule-associated proteins, including tau (predominantly found in axons) and MAP2 (predominantly found in dendrites). The phosphorylation state of tau and MAP2 modulates their interactions with microtubules. In their low-phosphorylation states, tau and MAP2 bind to microtubules and increase microtubule assembly and/or stability. Increased phosphorylation decreases these effects. Diez-Guerra and Avila [F.J. Diez-Guerra, J. Avila, MAP2 phosphorylation parallels dendrite arborization in hippocampal neurones in culture, NeuroReport 4 (1993) 412-419] found that protein phosphorylation correlates with neurite branching in cultured rat hippocampal neurons, and hypothesized that increased protein phosphorylation stimulates neurite branching. To test this hypothesis, we cultured rat hippocampal neurons in the presence of specific modulators of serine-threonine protein kinases and phosphatases. Inhibitors of several protein kinases, which would be expected to decrease protein phosphorylation, reduced branching. KT5720, an inhibitor of cyclic AMP-dependent protein kinase, and KN62, an inhibitor of Ca(2+)-calmodulin-dependent protein kinases, inhibited branching of both axons and dendrites. Calphostin C and chelerythrine, inhibitors of protein kinase C, inhibited branching of axons but not dendrites. Treatments that would be expected to increase protein phosphorylation, including inhibitors of protein

  9. Chronic homocysteine exposure causes changes in the intrinsic electrophysiological properties of cultured hippocampal neurons.

    Science.gov (United States)

    Schaub, Christina; Uebachs, Mischa; Beck, Heinz; Linnebank, Michael

    2013-04-01

    Homocystinuria is an inborn error of metabolism characterized by plasma homocysteine levels up to 500 μM, premature vascular events and mental retardation. Mild elevations of homocysteine plasma levels up to 25 μM, which are common in the general population, are associated with vascular disease, cognitive impairment and neurodegeneration. Several mechanisms of homocysteine neurotoxicity have been investigated. However, information on putative effects of hyperhomocysteinemia on the electrophysiology of neurons is limited. To screen for such effects, we examined primary cultures of mouse hippocampal neurons with the whole-cell patch-clamp technique. Homocysteine was applied intracellularly (100 μM), or cell cultures were incubated with 100 μM homocysteine for 24 h. Membrane voltage was measured in current-clamp mode, and action potential firing was induced with short and prolonged current injections. Single action potentials induced by short current injections (5 ms) were not altered by acute application or incubation of homocysteine. When we elicited trains of action potentials with prolonged current injections (200 ms), a broadening of action potentials during repetitive firing was observed in control neurons. This spike broadening was unaltered by acute application of homocysteine. However, it was significantly diminished when incubation with homocysteine was extended to 24 h prior to recording. Furthermore, the number of action potentials elicited by low current injections was reduced after long-term incubation with homocysteine, but not by the acute application. After 24 h of homocysteine incubation, the input resistance was reduced which might have contributed to the observed alterations in membrane excitability. We conclude that homocysteine exposure causes changes in the intrinsic electrophysiological properties of cultured hippocampal neurons as a mechanism of neurological symptoms of hyperhomocysteinemia.

  10. Neurogenic and neurotrophic effects of BDNF peptides in mouse hippocampal primary neuronal cell cultures.

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    Maria del Carmen Cardenas-Aguayo

    Full Text Available The level of brain-derived neurotrophic factor (BDNF, a member of the neurotrophin family, is down regulated in Alzheimer's disease (AD, Parkinson's disease (PD, depression, stress, and anxiety; conversely the level of this neurotrophin is increased in autism spectrum disorders. Thus, modulating the level of BDNF can be a potential therapeutic approach for nervous system pathologies. In the present study, we designed five different tetra peptides (peptides B-1 to B-5 corresponding to different active regions of BDNF. These tetra peptides were found to be non-toxic, and they induced the expression of neuronal markers in mouse embryonic day 18 (E18 primary hippocampal neuronal cultures. Additionally, peptide B-5 induced the expression of BDNF and its receptor, TrkB, suggesting a positive feedback mechanism. The BDNF peptides induced only a moderate activation (phosphorylation at Tyr 706 of the TrkB receptor, which could be blocked by the Trk's inhibitor, K252a. Peptide B-3, when combined with BDNF, potentiated the survival effect of this neurotrophin on H(2O(2-treated E18 hippocampal cells. Peptides B-3 and B-5 were found to work as partial agonists and as partial antagonists competing with BDNF to activate the TrkB receptor in a dose-dependent manner. Taken together, these results suggest that the described BDNF tetra peptides are neurotrophic, can modulate BDNF signaling in a partial agonist/antagonist way, and offer a novel therapeutic approach to neural pathologies where BDNF levels are dysregulated.

  11. Prototypical antipsychotic drugs protect hippocampal neuronal cultures against cell death induced by growth medium deprivation

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    Williams Sylvain

    2006-03-01

    Full Text Available Abstract Background Several clinical studies suggested that antipsychotic-based medications could ameliorate cognitive functions impaired in certain schizophrenic patients. Accordingly, we investigated the effects of various dopaminergic receptor antagonists – including atypical antipsychotics that are prescribed for the treatment of schizophrenia – in a model of toxicity using cultured hippocampal neurons, the hippocampus being a region of particular relevance to cognition. Results Hippocampal cell death induced by deprivation of growth medium constituents was strongly blocked by drugs including antipsychotics (10-10-10-6 M that display nM affinities for D2 and/or D4 receptors (clozapine, haloperidol, (±-sulpiride, domperidone, clozapine, risperidone, chlorpromazine, (+-butaclamol and L-741,742. These effects were shared by some caspases inhibitors and were not accompanied by inhibition of reactive oxygen species. In contrast, (--raclopride and remoxipride, two drugs that preferentially bind D2 over D4 receptors were ineffective, as well as the selective D3 receptor antagonist U 99194. Interestingly, (--raclopride (10-6 M was able to block the neuroprotective effect of the atypical antipsychotic clozapine (10-6 M. Conclusion Taken together, these data suggest that D2-like receptors, particularly the D4 subtype, mediate the neuroprotective effects of antipsychotic drugs possibly through a ROS-independent, caspase-dependent mechanism.

  12. Intracellular calcium elevation during plateau potentials mediated by extrasynaptic NMDA receptor activation in rat hippocampal CA1 pyramidal neurons is primarily due to calcium entry through voltage-gated calcium channels.

    Science.gov (United States)

    Oda, Yoshiaki; Kodama, Satoshi; Tsuchiya, Sadahiro; Inoue, Masashi; Miyakawa, Hiroyoshi

    2014-05-01

    We reported previously that plateau potentials mediated by extrasynaptic N-methyl-d-aspartate receptors (NMDARs) can be induced either by synaptic stimulation in the presence of glutamate transporter antagonist or by iontophoresis of NMDA in rat hippocampal CA1 pyramidal neurons. To examine whether the plateau potentials are accompanied by an elevation of intracellular Ca2+ and to determine the source of Ca2+ elevation, we performed Ca2+ imaging during the plateau potential. Neurons were loaded with Ca2+ indicator fluo-4, and the plateau potentials were generated either synaptically in the presence of glutamate transporter antagonist or by iontophoretically applying NMDA. We have found that a transient elevation in intracellular Ca2+ accompanies the plateau potential. The synaptically induced plateau potential and the Ca2+ elevation were blocked by 5,7-dichlorokynurenic acid (5,7-dCK), an antagonist for the glycine-binding sites of NMDAR. A mixture of Cd2+ and tetrodotoxin did not block NMDA-induced plateau potentials, but completely abolished the accompanying Ca2+ elevation in both the presence and absence of Mg2+ ions in the bathing solution. The NMDA-induced plateau potential was blocked by further adding 5,7-dCK. Our results show that the NMDAR-mediated plateau potential is accompanied by elevation of intracellular Ca2+ that is primarily caused by the influx of Ca2+ through voltage-gated Ca2+ channels. © 2014 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  13. Significant glial alterations in response to iron loading in a novel organotypic hippocampal slice culture model

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    Healy, Sinead; McMahon, Jill; Owens, Peter; FitzGerald, Una

    2016-01-01

    Aberrant iron deposition in the brain is associated with neurodegenerative disorders including Multiple Sclerosis, Alzheimer’s disease and Parkinson’s disease. To study the collective response to iron loading, we have used hippocampal organotypic slices as a platform to develop a novel ex vivo model of iron accumulation. We demonstrated differential uptake and toxicity of iron after 12 h exposure to 10 μM ferrous ammonium sulphate, ferric citrate or ferrocene. Having established the supremacy of ferrocene in this model, the cultures were then loaded with 0.1–100 μM ferrocene for 12 h. One μM ferrocene exposure produced the maximal 1.6-fold increase in iron compared with vehicle. This was accompanied by a 1.4-fold increase in ferritin transcripts and mild toxicity. Using dual-immunohistochemistry, we detected ferritin in oligodendrocytes, microglia, but rarely in astrocytes and never in neurons in iron-loaded slice cultures. Moreover, iron loading led to a 15% loss of olig2-positive cells and a 16% increase in number and greater activation of microglia compared with vehicle. However, there was no appreciable effect of iron loading on astrocytes. In what we believe is a significant advance on traditional mono- or dual-cultures, our novel ex vivo slice-culture model allows characterization of the collective response of brain cells to iron-loading. PMID:27808258

  14. NADPH oxidase mediates β-amyloid peptide-induced activation of ERK in hippocampal organotypic cultures

    Science.gov (United States)

    Serrano, Faridis; Chang, Angela; Hernandez, Caterina; Pautler, Robia G; Sweatt, J David; Klann, Eric

    2009-01-01

    Background Previous studies have shown that beta amyloid (Aβ) peptide triggers the activation of several signal transduction cascades in the hippocampus, including the extracellular signal-regulated kinase (ERK) cascade. In this study we sought to characterize the cellular localization of phosphorylated, active ERK in organotypic hippocampal cultures after acute exposure to either Aβ (1-42) or nicotine. Results We observed that Aβ and nicotine increased the levels of active ERK in distinct cellular localizations. We also examined whether phospho-ERK was regulated by redox signaling mechanisms and found that increases in active ERK induced by Aβ and nicotine were blocked by inhibitors of NADPH oxidase. Conclusion Our findings indicate that NADPH oxidase-dependent redox signaling is required for Aβ-induced activation of ERK, and suggest a similar mechanism may occur during early stages of Alzheimer's disease. PMID:19804648

  15. Methamphetamine modulates glutamatergic synaptic transmission in rat primary cultured hippocampal neurons.

    Science.gov (United States)

    Zhang, Shuzhuo; Jin, Yuelei; Liu, Xiaoyan; Yang, Lujia; Ge, Zhi juan; Wang, Hui; Li, Jin; Zheng, Jianquan

    2014-09-25

    Methamphetamine (METH) is a psychostimulant drug. Abuse of METH produces long-term behavioral changes including behavioral, sensitization, tolerance, and dependence. It induces neurotoxic effects in several areas of the brain via enhancing dopamine (DA) level abnormally, which may cause a secondary release of glutamate (GLU). However, repeated administration of METH still increases release of GLU even when dopamine content in tissue is significantly depleted. It implies that some other mechanisms are likely to involve in METH-induced GLU release. The goal of this study was to observe METH affected glutamatergic synaptic transmission in rat primary cultured hippocampal neurons and to explore the mechanism of METH modulated GLU release. Using whole-cell patch-clamp recordings, we found that METH (0.1-50.0μM) increased the frequency of spontaneous excitatory postsynaptic currents (sEPSCs) and miniature excitatory postsynaptic currents (mEPSCs). However, METH decreased the frequency of sEPSCs and mEPSCs at high concentration of 100μM. The postsynaptic NMDA receptor currents and P/Q-type calcium channel were not affected by the use of METH (10,100μM). METH did not present visible effect on N-type Ca(2+) channel current at the concentration lower than 50.0μM, but it was inhibited by use of METH at a 100μM. The effect of METH on glutamatergic synaptic transmission was not revered by pretreated with DA receptor antagonist SCH23390. These results suggest that METH directly modulated presynaptic GLU release at a different concentration, while dopaminergic system was not involved in METH modulated release of GLU in rat primary cultured hippocampal neurons.

  16. Full Length Bid is sufficient to induce apoptosis of cultured rat hippocampal neurons

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    Ward Manus W

    2007-02-01

    Full Text Available Abstract Background Bcl-2 homology domain (BH 3-only proteins are pro-apoptotic proteins of the Bcl-2 family that couple stress signals to the mitochondrial cell death pathways. The BH3-only protein Bid can be activated in response to death receptor activation via caspase 8-mediated cleavage into a truncated protein (tBid, which subsequently translocates to mitochondria and induces the release of cytochrome-C. Using a single-cell imaging approach of Bid cleavage and translocation during apoptosis, we have recently demonstrated that, in contrast to death receptor-induced apoptosis, caspase-independent excitotoxic apoptosis involves a translocation of full length Bid (FL-Bid from the cytosol to mitochondria. We induced a delayed excitotoxic cell death in cultured rat hippocampal neurons by a 5-min exposure to the glutamate receptor agonist N-methyl-D-aspartate (NMDA; 300 μM. Results Western blot experiments confirmed a translocation of FL-Bid to the mitochondria during excitotoxic apoptosis that was associated with the release of cytochrome-C from mitochondria. These results were confirmed by immunofluorescence analysis of Bid translocation during excitotoxic cell death using an antibody raised against the amino acids 1–58 of mouse Bid that is not able to detect tBid. Finally, inducible overexpression of FL-Bid or a Bid mutant that can not be cleaved by caspase-8 was sufficient to induce apoptosis in the hippocampal neuron cultures. Conclusion Our data suggest that translocation of FL-Bid is sufficient for the activation of mitochondrial cell death pathways in response to glutamate receptor overactivation.

  17. Functional P2X7 receptors at cultured hippocampal astrocytes but not neurons.

    Science.gov (United States)

    Rubini, Patrizia; Pagel, Gregor; Mehri, Soghra; Marquardt, Peter; Riedel, Thomas; Illes, Peter

    2014-10-01

    P2X7 receptors have been suggested to be located both on neurons and astrocytes of the central and peripheral nervous systems. In the present Ca(2+)-imaging and patch-clamp study, we reinvestigated these findings on mixed neuronal-astrocytic cell cultures prepared from embryonic or newborn rat hippocampi. We found in a Mg(2+)-free bath medium that the prototypic P2X7 receptor agonist dibenzoyl-adenosine triphosphate (Bz-ATP) increased the intracellular Ca(2+) concentration ([Ca(2+)]i) both in the neuronal cell bodies and in their axo-dendritic processes only to a very minor extent. However, Bz-ATP produced marked [Ca(2+)]i transients in the neuronal processes, when they grew above a glial carpet, which was uniformly sensitive to Bz-ATP. These glial signals might be misinterpreted as neuronal responses because of the poor focal discrimination by a fluorescent microscope. Most astrocytes had a polygonal shape without clearly circumscribable boundaries, but a subgroup of them had neuron-like appearance. The cellular processes of this astrocytic subgroup, just as their cell somata and their polygonal counterparts, appeared to possess a high density of functional P2X7 receptors. In contrast to astrocytes, in a low Ca(2+)/no Mg(2+)-containing bath medium, hippocampal neurons failed to respond to Bz-ATP with membrane currents. In addition, neither the amplitude nor the frequency of spontaneous excitatory postsynaptic currents, representing the quantal release of glutamate, was modified by Bz-ATP. We conclude that cultured hippocampal neurons, in contrast to astrocytes, possess P2X7 receptors, if at all, only at a low density.

  18. Inorganic lead may inhibit neurite development in cultured rat hippocampal neurons through hyperphosphorylation.

    Science.gov (United States)

    Kern, M; Audesirk, G

    1995-09-01

    Inorganic lead inhibits neurite initiation in cultured rat hippocampal neurons at concentrations as low as 100 nM. Conflicting reports suggest that Pb2+ may stimulate or inhibit protein kinase C, adenylyl cyclase, phosphodiesterase, and calmodulin, or increase intracellular free Ca2+ concentrations. Therefore, Pb2+ may alter the activities of Ca2+/calmodulin-dependent protein kinase (CaM kinase) or protein kinases C or A. We cultured rat hippocampal neurons in 100 nM PbCI2 alone or in combination with kinase or calmodulin inhibitors. Inhibiting protein kinase C with calphostin C exacerbated the inhibition of neurite initiation caused by PbCI2, but inhibiting protein kinase A with KT5720, CaM kinase with KN62, or calmodulin with calmidazolium completely reversed the effects of PbCI2. These results indicate that Pb2+ may inhibit neurite initiation by inappropriately stimulating protein phosphorylation by CaM kinase or cyclic AMP-dependent protein kinase (PKA), possibly by stimulating calmodulin. This hypothesis is supported by findings that other treatments that should increase protein phosphorylation (okadaic acid, a protein phosphatase inhibitor, and Sp-cAMPS, a PKA activator) also reduced neurite initiation. Whole-cell intracellular free Ca2+ ion concentrations were not significantly altered by 100 nM PbCI2 at 4, 12, 24, or 48 hr. Therefore, the hypothesized stimulatory effects of Pb2+ exposure on calmodulin, CaM kinase, or PKA are probably not caused by increases in whole-cell intracellular free Ca2+, but may be attributable either to intracellular Pb2+ or to localized increases in [Ca2+]in that are not reflected in whole-cell measurements.

  19. BDNF regulates the expression and distribution of vesicular glutamate transporters in cultured hippocampal neurons.

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    Carlos V Melo

    Full Text Available BDNF is a pro-survival protein involved in neuronal development and synaptic plasticity. BDNF strengthens excitatory synapses and contributes to LTP, presynaptically, through enhancement of glutamate release, and postsynaptically, via phosphorylation of neurotransmitter receptors, modulation of receptor traffic and activation of the translation machinery. We examined whether BDNF upregulated vesicular glutamate receptor (VGLUT 1 and 2 expression, which would partly account for the increased glutamate release in LTP. Cultured rat hippocampal neurons were incubated with 100 ng/ml BDNF, for different periods of time, and VGLUT gene and protein expression were assessed by real-time PCR and immunoblotting, respectively. At DIV7, exogenous application of BDNF rapidly increased VGLUT2 mRNA and protein levels, in a dose-dependent manner. VGLUT1 expression also increased but only transiently. However, at DIV14, BDNF stably increased VGLUT1 expression, whilst VGLUT2 levels remained low. Transcription inhibition with actinomycin-D or α-amanitine, and translation inhibition with emetine or anisomycin, fully blocked BDNF-induced VGLUT upregulation. Fluorescence microscopy imaging showed that BDNF stimulation upregulates the number, integrated density and intensity of VGLUT1 and VGLUT2 puncta in neurites of cultured hippocampal neurons (DIV7, indicating that the neurotrophin also affects the subcellular distribution of the transporter in developing neurons. Increased VGLUT1 somatic signals were also found 3 h after stimulation with BDNF, further suggesting an increased de novo transcription and translation. BDNF regulation of VGLUT expression was specifically mediated by BDNF, as no effect was found upon application of IGF-1 or bFGF, which activate other receptor tyrosine kinases. Moreover, inhibition of TrkB receptors with K252a and PLCγ signaling with U-73122 precluded BDNF-induced VGLUT upregulation. Hippocampal neurons express both isoforms during

  20. The role of dendritic action potentials and Ca2+ influx in the induction of homosynaptic long-term depression in hippocampal CA1 pyramidal neurons.

    Science.gov (United States)

    Christie, B R; Magee, J C; Johnston, D

    1996-01-01

    Long-term depression (LTD) of synaptic efficacy at CA1 synapses is believed to be a Ca(2+)-dependent process. We used high-speed fluorescence imaging and patch-clamp techniques to quantify the spatial distribution of changes in intracellular Ca2+ accompanying the induction of LTD at Schaffer collateral synapses in CA1 pyramidal neurons. Low-frequency stimulation (3 Hz), which was subthreshold for action potentials, produced small changes in [Ca2+]i and failed to elicit LTD. Increasing the stimulus strength so that action potentials were generated produced both robust LTD and increases in [Ca2+]i. Back-propagating action potentials at 3 Hz in the absence of synaptic stimulation also produced increases in [Ca2+]i, but failed to induce LTD. When subthreshold synaptic stimulation was paired with back-propagating action potentials, however, large increases in [Ca2+]i were observed and robust LTD was induced. The LTD was blocked by the N-methyl-D-aspartate receptor (NMDAr) antagonist APV, and stimulus-induced increases in [Ca2+]i were reduced throughout the neuron under these conditions. The LTD was also dependent on Ca2+ influx via voltage-gated Ca2+ channels (VGCCs), because LTD was severely attenuated or blocked by both nimodipine and Ni2+. These findings suggest that back-propagating action potentials can exert a powerful control over the induction of LTD and that both VGCCs and NMDArs are involved in the induction of this form of plasticity.

  1. Comparison of neuroprotective effects of erythropoietin (EPO) and carbamylerythropoietin (CEPO) against ischemia-like oxygen-glucose deprivation (OGD) and NMDA excitotoxicity in mouse hippocampal slice cultures

    DEFF Research Database (Denmark)

    Montero, Maria; Rom Poulsen, Frantz; Noraberg, Jens;

    2007-01-01

    of hematopoietic bioactivity, is the chemically modified, EPO-derivative carbamylerythropoietin (CEPO). For comparison of the neuroprotective effects of CEPO and EPO, we subjected organotypic hippocampal slice cultures to oxygen-glucose deprivation (OGD) or N-methyl-d-aspartate (NMDA) excitotoxicity. Hippocampal...

  2. Acute death of astrocytes in blast-exposed rat organotypic hippocampal slice cultures

    Science.gov (United States)

    Miller, Anna P.; Shah, Alok S.; Aperi, Brandy V.; Kurpad, Shekar N.; Stemper, Brian D.; Glavaski-Joksimovic, Aleksandra

    2017-01-01

    Blast traumatic brain injury (bTBI) affects civilians, soldiers, and veterans worldwide and presents significant health concerns. The mechanisms of neurodegeneration following bTBI remain elusive and current therapies are largely ineffective. It is important to better characterize blast-evoked cellular changes and underlying mechanisms in order to develop more effective therapies. In the present study, our group utilized rat organotypic hippocampal slice cultures (OHCs) as an in vitro system to model bTBI. OHCs were exposed to either 138 ± 22 kPa (low) or 273 ± 23 kPa (high) overpressures using an open-ended helium-driven shock tube, or were assigned to sham control group. At 2 hours (h) following injury, we have characterized the astrocytic response to a blast overpressure. Immunostaining against the astrocytic marker glial fibrillary acidic protein (GFAP) revealed acute shearing and morphological changes in astrocytes, including clasmatodendrosis. Moreover, overlap of GFAP immunostaining and propidium iodide (PI) indicated astrocytic death. Quantification of the number of dead astrocytes per counting area in the hippocampal cornu Ammonis 1 region (CA1), demonstrated a significant increase in dead astrocytes in the low- and high-blast, compared to sham control OHCs. However only a small number of GFAP-expressing astrocytes were co-labeled with the apoptotic marker Annexin V, suggesting necrosis as the primary type of cell death in the acute phase following blast exposure. Moreover, western blot analyses revealed calpain mediated breakdown of GFAP. The dextran exclusion additionally indicated membrane disruption as a potential mechanism of acute astrocytic death. Furthermore, although blast exposure did not evoke significant changes in glutamate transporter 1 (GLT-1) expression, loss of GLT-1-expressing astrocytes suggests dysregulation of glutamate uptake following injury. Our data illustrate the profound effect of blast overpressure on astrocytes in OHCs at 2 h

  3. GDNF pre-treatment aggravates neuronal cell loss in oxygen-glucose deprived hippocampal slice cultures: a possible effect of glutamate transporter up-regulation.

    Science.gov (United States)

    Bonde, C; Sarup, A; Schousboe, A; Gegelashvili, G; Noraberg, J; Zimmer, J

    2003-01-01

    Besides its neurotrophic and neuroprotective effects on dopaminergic neurons and spinal motoneurons, glial cell line-derived neurotrophic factor (GDNF) has potent neuroprotective effects in cerebral ischemia. The protective effect has so far been related to reduced activation of N-methyl-D-aspartate receptors (NMDAr). This study tested the effects of GDNF on glutamate transporter expression, with the hypothesis that modulation of glutamate transporter activity would affect the outcome of cerebral ischemia. Organotypic hippocampal slice cultures, derived from 1-week-old rats, were treated with 100 ng/ml GDNF for either 2 or 5 days, followed by Western blot analysis of NMDAr subunit 1 (NR1) and two glutamate transporter subtypes, GLAST and GLT-1. After 5-day exposure to GDNF, expression of GLAST and GLT-1 was up-regulated to 169 and 181% of control values, respectively, whereas NR1 was down-regulated to 64% of control. However, despite these changes that potentially would support neuronal resistance to excitotoxicity, the long-term treatment with GDNF was found to aggravate the neuronal damage induced by oxygen-glucose deprivation (OGD). The increased cell death, assessed by propidium iodide (PI) uptake, occurred not only among the most susceptible CA1 pyramidal cells, but also in CA3 and fascia dentata. Given that glutamate transporters are able to release glutamate by reversed action during energy failure, it is suggested that the observed increase in OGD-induced cell death in the GDNF-pretreated cultures was caused by the build-up of excitotoxic concentrations of extracellular glutamate released through the glutamate transporters, which were up-regulated by GDNF. Although the extent and consequences of glutamate release via reversal of GLAST and GLT-1 transporters seem to vary in different energy failure models, the present findings should be taken into account in clinical trials of GDNF.

  4. Role of reuniens nucleus projections to the medial prefrontal cortex and to the hippocampal pyramidal CA1 area in associative learning.

    Directory of Open Access Journals (Sweden)

    Lyndell Eleore

    Full Text Available We studied the interactions between short- and long-term plastic changes taking place during the acquisition of a classical eyeblink conditioning and following high-frequency stimulation (HFS of the reuniens nucleus in behaving mice. Synaptic changes in strength were studied at the reuniens-medial prefrontal cortex (mPFC and the reuniens-CA1 synapses. Input/output curves and a paired-pulse study enabled determining the functional capabilities of the two synapses and the optimal intensities to be applied at the reuniens nucleus during classical eyeblink conditioning and for HFS applied to the reuniens nucleus. Animals were conditioned using a trace paradigm, with a tone as conditioned stimulus (CS and an electric shock to the trigeminal nerve as unconditioned stimulus (US. A single pulse was presented to the reuniens nucleus to evoke field EPSPs (fEPSPs in mPFC and CA1 areas during the CS-US interval. No significant changes in synaptic strength were observed at the reuniens-mPFC and reuniens-CA1 synapses during the acquisition of eyelid conditioned responses (CRs. Two successive HFS sessions carried out during the first two conditioning days decreased the percentage of CRs, without evoking any long-term potentiation (LTP at the recording sites. HFS of the reuniens nucleus also prevented the proper acquisition of an object discrimination task. A subsequent study revealed that HFS of the reuniens nucleus evoked a significant decrease of paired-pulse facilitation. In conclusion, reuniens nucleus projections to prefrontal and hippocampal circuits seem to participate in the acquisition of associative learning through a mechanism that does not required the development of LTP.

  5. Nanoparticle Targeting to Neurons in a Rat Hippocampal Slice Culture Model

    Directory of Open Access Journals (Sweden)

    Ryan Walters

    2012-09-01

    Full Text Available We have previously shown that CdSe/ZnS core/shell luminescent semiconductor nanocrystals or QDs (quantum dots coated with PEG [poly(ethylene glycol]-appended DHLA (dihydrolipoic acid can bind AcWG(PalVKIKKP9GGH6 (Palm1 through the histidine residues. The coating on the QD provides colloidal stability and this peptide complex uniquely allows the QDs to be taken up by cultured cells and readily exit the endosome into the soma. We now show that use of a polyampholyte coating [in which the neutral PEG is replaced by the negatively heterocharged CL4 (compact ligand], results in the specific targeting of the palmitoylated peptide to neurons in mature rat hippocampal slice cultures. There was no noticeable uptake by astrocytes, oligodendrocytes or microglia (identified by immunocytochemistry, demonstrating neuronal specificity to the overall negatively charged CL4 coating. In addition, EM (electron microscopy images confirm the endosomal egress ability of the Palm1 peptide by showing a much more disperse cytosolic distribution of the CL4 QDs conjugated to Palm1 compared with CL4 QDs alone. This suggests a novel and robust way of delivering neurotherapeutics to neurons.

  6. Deoxyschisandrin modulates synchronized Ca2+ oscillations and spontaneous synaptic transmission of cultured hippocampal neurons

    Institute of Scientific and Technical Information of China (English)

    Min FU; Zhao-hui SUN; Min ZONG; Xiang-ping HE; Huan-cong ZUO; Zuo-ping XIE

    2008-01-01

    Aim: Deoxyschisandrin is one of the most effective composites of Schisandra chinensis, a famous Chinese medicine widely used as an antistress, anti-aging, and neurological performance-improving herb. In this study, we examined its spe- cific mechanisms of action on cultured hippocampal neurons. Methods: Hippoc- ampal neurons, primarily cultured for 9-11 d in vitro, were used for this study. DS were dissolved in DMSO and applied to calcium imaging and whole-cell patch clamp. Results: The application of 3 mg/L DS decreased the frequency of sponta- neous and synchronous oscillations of intracellular Ca2+ to 72%±2% (mean±SEM), and the spontaneous inhibitory postsynaptic currents to 60%±3% (mean±SEM). The inhibitory concentraton 50% (IC50) for the effect of DS on calcium oscillations was 3.8 mg/L. DS also depressed the high voltage-gated Ca2+ channel and the voltage-gated Na+ channel currents at the same time point. It had no effect, however, on voltage-gated K+ and spontaneous excitatory postsynaptic currents. Conclusion: DS inhibited the spontaneous and synchronous oscillations of intra- cellular Ca2+ through the depression of influx of extracellular calcium and the initiation of action potential. By repressing the spontaneous neurotransmitter release, DS modulated the neuronal network activities.

  7. NRSF causes cAMP-sensitive suppression of sodium current in cultured hippocampal neurons

    Science.gov (United States)

    Nadeau, H.; Lester, H. A.

    2002-01-01

    The neuron restrictive silencer factor (NRSF/REST) has been shown to bind to the promoters of many neuron-specific genes and is able to suppress transcription of Na(+) channels in PC12 cells, although its functional effect in terminally differentiated neurons is unknown. We constructed lentiviral vectors to express NRSF as a bicistronic message with green fluorescent protein (GFP) and followed infected hippocampal neurons in culture over a period of 1-2 wk. NRSF-expressing neurons showed a time-dependent suppression of Na(+) channel function as measured by whole cell electrophysiology. Suppression was reversed or prevented by the addition of membrane-permeable cAMP analogues and enhanced by cAMP antagonists but not affected by increasing protein expression with a viral enhancer. Secondary effects, including altered sensitivity to glutamate and GABA and reduced outward K(+) currents, were duplicated by culturing GFP-infected control neurons in TTX. The striking similarity of the phenotypes makes NRSF potentially useful as a genetic "silencer" and also suggests avenues of further exploration that may elucidate the transcription factor's in vivo role in neuronal plasticity.

  8. Nanoparticle targeting to neurons in a rat hippocampal slice culture model

    Directory of Open Access Journals (Sweden)

    Richard P Kraig

    2012-10-01

    Full Text Available We have previously shown that CdSe/ZnS core/shell luminescent semiconductor nanocrystals or QDs (quantum dots coated with PEG [poly(ethylene glycol]-appended DHLA (dihydrolipoic acid can bind AcWG(PalVKIKKP9GGH6 (Palm1 through the histidine residues. The coating on the QD provides colloidal stability and this peptide complex uniquely allows the QDs to be taken up by cultured cells and readily exit the endosome into the soma. We now show that use of a polyampholyte coating [in which the neutral PEG is replaced by the negatively heterocharged CL4 (compact ligand], results in the specific targeting of the palmitoylated peptide to neurons in mature rat hippocampal slice cultures. There was no noticeable uptake by astrocytes, oligodendrocytes or microglia (identified by immunocytochemistry, demonstrating neuronal specificity to the overall negatively charged CL4 coating. In addition, EM (electron microscopy images confirm the endosomal egress ability of the Palm1 peptide by showing a much more disperse cytosolic distribution of the CL4 QDs conjugated to Palm1 compared with CL4 QDs alone. This suggests a novel and robust way of delivering neurotherapeutics to neurons.

  9. Ionotropic glutamate receptors and glutamate transporters are involved in necrotic neuronal cell death induced by oxygen-glucose deprivation of hippocampal slice cultures.

    Science.gov (United States)

    Bonde, C; Noraberg, J; Noer, H; Zimmer, J

    2005-01-01

    Organotypic hippocampal slice cultures represent a feasible model for studies of cerebral ischemia and the role of ionotropic glutamate receptors in oxygen-glucose deprivation-induced neurodegeneration. New results and a review of existing data are presented in the first part of this paper. The role of glutamate transporters, with special reference to recent results on inhibition of glutamate transporters under normal and energy-failure (ischemia-like) conditions is reviewed in the last part of the paper. The experimental work is based on hippocampal slice cultures derived from 7 day old rats and grown for about 3 weeks. In such cultures we investigated the subfield neuronal susceptibility to oxygen-glucose deprivation, the type of induced cell death and the involvement of ionotropic glutamate receptors. Hippocampal slice cultures were also used in our studies on glutamate transporters reviewed in the last part of this paper. Neurodegeneration was monitored and/or shown by cellular uptake of propidium iodide, loss of immunocytochemical staining for microtubule-associated protein 2 and staining with Fluoro-Jade B. To distinguish between necrotic vs. apoptotic neuronal cell death we used immunocytochemical staining for active caspase-3 (apoptosis indicator) and Hoechst 33342 staining of nuclear chromatin. Our experimental studies on oxygen-glucose deprivation confirmed that CA1 pyramidal cells were the most susceptible to this ischemia-like condition. Judged by propidium iodide uptake, a selective CA1 lesion, with only minor affection on CA3, occurred in cultures exposed to oxygen-glucose deprivation for 30 min. Nuclear chromatin staining by Hoechst 33342 and staining for active caspase-3 showed that oxygen-glucose deprivation induced necrotic cell death only. Addition of 10 microM of the N-methyl-D-aspartate glutamate receptor antagonist MK-801, and 20 microM of the non-N-methyl-D-aspartate glutamate receptor antagonist 2,3-dihyroxy-6-nitro-7-sulfamoyl

  10. Resveratrol increases antioxidant defenses and decreases proinflammatory cytokines in hippocampal astrocyte cultures from newborn, adult and aged Wistar rats.

    Science.gov (United States)

    Bellaver, Bruna; Souza, Débora Guerini; Souza, Diogo Onofre; Quincozes-Santos, André

    2014-06-01

    Astrocytes are responsible for modulating neurotransmitter systems and synaptic information processing, ionic homeostasis, energy metabolism, maintenance of the blood-brain barrier, and antioxidant and inflammatory responses. Our group recently published a culture model of cortical astrocytes obtained from adult Wistar rats. In this study, we established an in vitro model for hippocampal astrocyte cultures from adult (90 days old) and aged (180 days old) Wistar rats. Resveratrol, a polyphenol found in grapes and red wine, exhibits antioxidant, anti-inflammatory, anti-aging and neuroprotective effects that modulate glial functions. Here, we evaluated the effects of resveratrol on GSH content, GS activity, TNF-α and IL-1β levels in hippocampal astrocytes from newborn, adult and aged Wistar rats. We observed a decrease in antioxidant defenses and an increase in the inflammatory response in hippocampal astrocytes from adult and aged rats compared to classical astrocyte cultures from newborn rats. Resveratrol prevented these effects. These findings reinforce the neuroprotective effects of resveratrol, which are mainly associated with antioxidant and anti-inflammatory activities.

  11. Developmental Expression of Kv Potassium Channels at the Axon Initial Segment of Cultured Hippocampal Neurons

    Science.gov (United States)

    Sánchez-Ponce, Diana; DeFelipe, Javier; Garrido, Juan José; Muñoz, Alberto

    2012-01-01

    Axonal outgrowth and the formation of the axon initial segment (AIS) are early events in the acquisition of neuronal polarity. The AIS is characterized by a high concentration of voltage-dependent sodium and potassium channels. However, the specific ion channel subunits present and their precise localization in this axonal subdomain vary both during development and among the types of neurons, probably determining their firing characteristics in response to stimulation. Here, we characterize the developmental expression of different subfamilies of voltage-gated potassium channels in the AISs of cultured mouse hippocampal neurons, including subunits Kv1.2, Kv2.2 and Kv7.2. In contrast to the early appearance of voltage-gated sodium channels and the Kv7.2 subunit at the AIS, Kv1.2 and Kv2.2 subunits were tethered at the AIS only after 10 days in vitro. Interestingly, we observed different patterns of Kv1.2 and Kv2.2 subunit expression, with each confined to distinct neuronal populations. The accumulation of Kv1.2 and Kv2.2 subunits at the AIS was dependent on ankyrin G tethering, it was not affected by disruption of the actin cytoskeleton and it was resistant to detergent extraction, as described previously for other AIS proteins. This distribution of potassium channels in the AIS further emphasizes the heterogeneity of this structure in different neuronal populations, as proposed previously, and suggests corresponding differences in action potential regulation. PMID:23119056

  12. The Susd2 protein regulates neurite growth and excitatory synaptic density in hippocampal cultures.

    Science.gov (United States)

    Nadjar, Yann; Triller, Antoine; Bessereau, Jean-Louis; Dumoulin, Andrea

    2015-03-01

    Complement control protein (CCP) domains have adhesion properties and are commonly found in proteins that control the complement immune system. However, an increasing number of proteins containing CCP domains have been reported to display neuronal functions. Susd2 is a transmembrane protein containing one CCP domain. It was previously identified as a tumor-reversing protein, but has no characterized function in the CNS. The present study investigates the expression and function of Susd2 in the rat hippocampus. Characterization of Susd2 during development showed a peak in mRNA expression two weeks after birth. In hippocampal neuronal cultures, the same expression profile was observed at 15days in vitro for both mRNA and protein, a time consistent with synaptogenesis in our model. At the subcellular level, Susd2 was located on the soma, axons and dendrites, and appeared to associate preferentially with excitatory synapses. Inhibition of Susd2 by shRNAs led to decreased numbers of excitatory synaptic profiles, exclusively. Also, morphological parameters were studied on young (5DIV) developing neurons. After Susd2 inhibition, an increase in dendritic tree length but a decrease in axon elongation were observed, suggesting changes in adhesion properties. Our results demonstrate a dual role for Susd2 at different developmental stages, and raise the question whether Susd2 and other CCP-containing proteins expressed in the CNS could be function-related.

  13. Stimulation of glutamate receptors in cultured hippocampal neurons causes Ca2+-dependent mitochondrial contraction.

    Science.gov (United States)

    Brustovetsky, Tatiana; Li, Viacheslav; Brustovetsky, Nickolay

    2009-07-01

    Cultured hippocampal neurons expressing mitochondrially-targeted enhanced yellow fluorescent protein (mito-eYFP) were used to quantitatively examine mitochondrial remodelling in response to excitotoxic glutamate. Mitochondrial morphology was evaluated using laser spinning-disk confocal microscopy followed by calibrated image processing and 3D image rendering. Glutamate triggered an increase in cytosolic Ca(2+) and mitochondrial depolarization accompanied by Ca(2+)-dependent morphological transformation of neuronal mitochondria from "thread-like" to rounded structures. The quantitative analysis of the mitochondrial remodelling revealed that exposure to glutamate resulted in a decrease in mitochondrial volume and surface area concurrent with an increase in sphericity of the organelles. NIM811, an inhibitor of the mitochondrial permeability transition, attenuated the glutamate-induced sustained increase in cytosolic Ca(2+) and suppressed mitochondrial remodelling in the majority of affected neurons, but it did not rescue mitochondrial membrane potential. Shortening, fragmentation, and formation of circular mitochondria with decreased volume and surface area accompanied mitochondrial depolarization with FCCP. However, FCCP-induced morphological alterations appeared to be distinctly different from mitochondrial remodelling caused by glutamate. Moreover, FCCP prevented glutamate-induced mitochondrial remodelling suggesting an important role of Ca(2+) influx into mitochondria in the morphological alterations. Consistent with this, in saponin-permeabilized neurons, Ca(2+) caused mitochondrial remodelling which could be prevented by Ru(360).

  14. Changes in mitochondrial function in primary culture of rat’s hippocampal neurons after exposure to electromagnetic field

    Directory of Open Access Journals (Sweden)

    Ming-yue QU

    2014-10-01

    Full Text Available Objective To investigate the changes in mitochondrial function in rat's hippocampal neurons of primary culture after exposure to electromagnetic field (EMF. Methods Rat's hippocampal neurons of primary culture were exposed to EMF irradiation (2.45GHz with average power density of 5, 10, 30 and 60 mW/cm2 for 10 minutes. CCK-8 kit and LDH kit were used to determine the injurious effects on rat hippocampal neurons at 0, 3, 6, 12, 24 and 48 hours after irradiation. Reactive oxygen species (ROS were detected using fluorescent probe DCFH-DA, mitochondrial membrane potential (ΔΨm was assessed using fluorescent probe JC-1, mitochondrial permeability transition pore (mPTP opening was determined by calcein-fluorescence quenching method, and the intracellular ATP levels were determined by ATP detection kit at 12 hours after irradiation. Results  Hippocampal neuron damage was found after EMF irradiation, and it was aggravated by an increase in power density. Compared with the control, the viability of hippocampal neurons decreased significantly at 12, 24 and 48 h (P<0.05, and LDH levels increased at 24 and 48 h (P<0.05 after 10 mW/cm2 irradiation, while their viability decreased at 3, 6, 12, 24 and 48 h (P<0.05, P<0.01, and LDH levels increased at 6, 12, 24 and 48 h (P<0.05, P<0.01 after 30 and 60 mW/cm2 irradiation. Compared with the control, the mitochondrial ROS level was elevated significantly (P<0.05, P<0.01 after 5, 10, 30 and 60 mW/cm2 irradiation, while ΔΨm and ATP levels lowered and mPTP was obviously opened and activated (P<0.05, P<0.01 after 10, 30 and 60 mW/cm2 irradiation. Conclusion EMF irradiation may induce damage to rat's hippocampal neurons of primary culture in dose- and time-dependent manners, and mitochondrial dysfunction occurs during the exposure. DOI: 10.11855/j.issn.0577-7402.2014.08.12

  15. BK channel activity determines the extent of cell degeneration after oxygen and glucose deprivation: a study in organotypical hippocampal slice cultures.

    Science.gov (United States)

    Rundén-Pran, E; Haug, F M; Storm, J F; Ottersen, O P

    2002-01-01

    BK channels are voltage- and calcium-dependent potassium channels whose activation tends to reduce cellular excitability. In hippocampal pyramidal cells, BK channels repolarize somatic action potentials, and recent immunogold and electrophysiological analyses have revealed a presynaptic pool of BK channels that can regulate glutamate release. Agents that modulate BK channel activity would therefore be expected to affect cell excitability and neurotransmitter release also under pathological conditions. We have investigated the role of BK potassium channels in a model of ischemia-induced nerve cell degeneration. Organotypical slice cultures of rat hippocampus were exposed to oxygen and glucose deprivation (OGD), and cell death was assessed by the fluorescent dye propidium iodide. OGD induced cell death in the CA1 region and to a lesser extent in CA3. Treatment with the BK channel blockers, paxilline and iberiotoxin, during and after OGD induced increased cell death in CA1 and CA3. Both BK channel blockers also sensitized the relatively resistant granule cells in fascia dentata to OGD. The effect of paxilline and iberiotoxin was evident from 3 h after OGD, indicating a role of BK channels early in the post-ischemic phase or during OGD itself. The BK channel opener, NS1619, turned out to be gliotoxic, and this effect was not counteracted by paxilline and iberiotoxin. Our data show that blockade of BK channels aggravates OGD-induced cell damage and suggest that BK channels act as a kind of 'emergency brake' during and/or after ischemia. Accordingly, the BK channel is a potential molecular target for neuroprotective therapy in stroke.

  16. Spatiotemporal evidence of apoptosis-mediated ischemic injury in organotypic hippocampal slice cultures.

    Science.gov (United States)

    Cho, Seongeun; Liu, Danni; Fairman, Denise; Li, Ping; Jenkins, Lorayne; McGonigle, Paul; Wood, Andrew

    2004-07-01

    Oxygen-glucose deprivation (OGD) induced neuron-specific cell death in organotypic hippocampal slice cultures. Neuronal death was first evident in the CA1 region 24 h after the injury as assessed by propidium iodide (PI) labeling, and continued to extend to the CA3/4 region up to 72 h. At 6 days post-OGD, PI labeling was weak and diffuse with no clear demarcation of pyknotic nuclei. To characterize biochemical changes produced by OGD, cellular efflux of three key amino acid neurotransmitters was evaluated. OGD elicited large increases in the release of GABA and aspartate (55- and 4.5-fold increase over basal, respectively), while there were no detectable changes in extracellular glutamate levels. In order to ascertain the existence of the synaptic pool of glutamate, sister cultures were treated with sodium azide. This evoked a strong increase in glutamate release, suggesting the intactness of the glutamate system. Further studies revealed a time-dependent activation of caspase 3 following OGD, shown by immunoblot analysis as well as by confocal laser scanning microscopy. While we did not observe the activation of caspases 1, 2, or 8 in our model, the activation of caspase 9 was evident, peaking at 12 h post-OGD. Despite no apparent increase in glutamate release by ischemic slices, treatment with a N-methyl-D-aspartate (NMDA) antagonist or an alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) antagonist significantly reduced neuronal death. Furthermore, a pan-caspase inhibitor (zVAD-fmk), but not the caspase 3 inhibitor (DEVD-fmk), provided partial neuroprotection. Inhibition of a Ca(2+)-dependent cysteine protease, calpain, by MDL28170 also elicited partial neuroprotective effects.

  17. The effects of triethyl lead on the development of hippocampal neurons in culture.

    Science.gov (United States)

    Audesirk, T; Shugarts, D; Cabell-Kluch, L; Wardle, K

    1995-02-01

    Triethyl lead is the major metabolite of tetraethyl lead, which is used in industrial processes and as an antiknock additive to gasoline. We tested the hypothesis that low levels of triethyl lead (0.1 nmol/L to 5 mumol/L) interfere with the normal development of cultured E18 rat hippocampal neurons, possibly through increases in intracellular free calcium ion concentration, [Ca2+]in. The study assessed survival and differentiation using morphometric analysis of individual neurons. We also looked at short-term (up to 3.75-h) changes in intracellular calcium using the calcium-sensitive dye fura-2. Survival of neurons was significantly reduced at 5 mumol/L, and overall production of neurites was reduced at > or = 2 mumol/L. The length of axons and the number of axons and dendrites were reduced at > or = 1 mumol/L. Neurite branching was inhibited at 10 nmol/L for dendrites and 100 nmol/L for axons. Increases in intracellular calcium were observed during a 3.75-h exposure of newly plated neurons to 5 mumol/L triethyl lead. These increases were prevented by BAPTA-AM; which clamps [Ca2+]in at about 100 nmol/L. Culturing neurons with BAPTA-AM and 5 mumol/L triethyl lead did not reverse the effects of triethyl lead, suggesting that elevation of [Ca2+]in is not responsible for decreases in survival and neurite production. Triethyl lead has been shown to disrupt cytoskeletal elements, particularly neurofilaments, at very low levels, suggesting a possible mechanism for its inhibition of neurite branching at nanomolar concentrations.

  18. Pyramid Schemes on the Tibetan Plateau

    OpenAIRE

    Devin Gonier; Rgyal yum sgrol ma

    2012-01-01

    The unique features of pyramid schemes and certain underlying causes for their development on the Tibetan Plateau are analyzed. Research was conducted by analyzing 521 surveys, allowing estimation of pyramid scheme activity on the Plateau and an identification of related cultural and social specificities. Firsthand accounts were collected revealing details of personal involvement. Survey data and similarities in the accounts were studied to suggest how involvement in pyramid schemes might be ...

  19. Neuregulin directly decreases voltage-gated sodium current in hippocampal ErbB4-expressing interneurons.

    Science.gov (United States)

    Janssen, Megan J; Leiva-Salcedo, Elias; Buonanno, Andres

    2012-10-03

    The Neuregulin 1 (NRG1)/ErbB4 signaling pathway has been genetically and functionally implicated in the etiology underlying schizophrenia, and in the regulation of glutamatergic pyramidal neuron function and plasticity. However, ErbB4 receptors are expressed in subpopulations of GABAergic interneurons, but not in hippocampal or cortical pyramidal neurons, indicating that NRG1 effects on principal neurons are indirect. Consistent with these findings, NRG1 effects on hippocampal long-term potentiation at CA1 pyramidal neuron synapses in slices are mediated indirectly by dopamine. Here we studied whether NRG/ErbB signaling directly regulates interneuron intrinsic excitability by pharmacologically isolating ErbB4-expressing neurons in rat dissociated hippocampal cultures, which lack dopaminergic innervation. We found that NRG1 acutely attenuates ErbB4-expressing interneuron excitability by depolarizing the firing threshold; neurons treated with the pan-ErbB inhibitor PD158780 or negative for ErbB4 were unaffected. These effects of NRG1 are primarily attributable to decreased voltage-gated sodium channel activity, as current density was attenuated by ∼60%. In stark contrast, NRG1 had minor effects on whole-cell potassium currents. Our data reveal the direct actions of NRG1 signaling in ErbB4-expressing interneurons, and offer novel insight into how NRG1/ErbB4 signaling can impact hippocampal activity.

  20. Rapid effect of stress concentration corticosterone on glutamate receptor and its subtype NMDA receptor activity in cultured hippocampal neurons

    Institute of Scientific and Technical Information of China (English)

    刘玲; 孙继虎; 王春安

    2003-01-01

    Objective:To study the rapid effect of glucocorticoids(GCs)on NMDA receptor activity in hippocampal neurons in stress and to elucidate its underlying probable membrane mechanisms.Methods:Whole-cell patch-clamp recording was used to assess the effect of stress concentration corticosterone(B)on the responses of cultured hippocampal neurons to glutamate and NMDA(N-methy-D-asparatic acid).To make clear the target of B,intracellular dialysis of B(10 μ mol/L)through patch pipette and extracellular application of bovine serum albumin-conjugated corticosterone(B-BSA,10 μmol/L)were carried out to observe their influence on peak amplitude of NMDA-evoked current.Results:B had a rapid,reversible and inhibitory effect on peak amplitude of GLU- or NMDA-evoked current in cultured hippocampal neurons.Furthermore,B-BSA had the inhibitory effect on INMDA as that of B,but intracellularly dialyzed B had no significant effect on INMDA.Conclusion:These results suggest that under the condition of stress,GCs may rapidly,negatively regulate excitatory synaptic receptors-glutamate receptors(GluRs),especially NMDA receptor(NMDAR)in central nervous system,which is mediated by rapid membrane mechanisms,but not by classical,genomic mechanisms.

  1. The changes of brain-derived neurotrophic factor positive neurons and the morphology of pyramidal cells in hippocampal in sodium valproate induced autism rats%丙戊酸钠孤独症模型鼠海马脑源性神经营养因子阳性神经元表达及锥体细胞形态学的变化

    Institute of Scientific and Technical Information of China (English)

    衣明纪; 马小旭; 李音

    2013-01-01

    目的 观察丙戊酸钠(VPA)孤独症模型鼠海马脑源性神经营养因子(BDNF)阳性神经元表达及锥体细胞形态学改变.方法 按Schneider方法制作VPA孤独症动物模型,采用免疫组化和图像分析技术检测模型鼠海马CA1区BDNF阳性神经元表达水平及海马CA1区锥体细胞形态学的改变.结果 孤独症模型组与正常对照组比较,海马CA1区锥体细胞BDNF阳性神经元表达水平增强,孤独症模型组与正常对照组阳性细胞数分别为(5.00±1.60)/视野和(3.00±1.04)/视野,差异有统计学意义(t=3.63,P=0.0015);海马CA1区锥体细胞形态学显示,孤独症模型鼠海马CA1区锥体神经元发生凋亡增加.结论 孤独症的发病可能与海马CA1区锥体细胞BDNF表达水平以及锥体神经细胞的凋亡有关.%Objective To explore the pathogenesis of autism by observation of changes of brain-derived neurotrophic factor(BDNF) positive neurons and the morphology of pyramidal cells in hippocampal CA1 region,and provide theoretical evidence for the therapeutic schedule.Methods Animal model of autism was obtained by Schneider method.Using the immunohistochemistry methods and image analysis,the number of BDNF positive neurons was examined in hippocampal CA1 region of the autism model rats and the normal rats,and the changes of pyramidal cell were observed in hippocampal CA1 region after HE staining.Results The numbers of BDNF positive neurons in the hippocampal CA1 region of the autism model rats were more than those of the normal rats (5.00 ±1.60 vs 3.00 ± 1.04,t =3.63,P =0.0015).The morphology of pyramidal cells showed that the pyramidal cells of the autism model rats in hippocampal CA1 region had apoptosis.Conclusion The occurrence of autism may be related to the changes of BDNF and the morphology of pyramidal cells in hippocampal CA1 region.

  2. Membrane voltage modulates the GABA(A) receptor gating in cultured rat hippocampal neurons.

    Science.gov (United States)

    Pytel, Maria; Mercik, Katarzyna; Mozrzymas, Jerzy W

    2006-02-01

    The kinetics of GABAergic currents in neurons is known to be modulated by the membrane voltage but the underlying mechanisms have not been fully explored. In particular, the impact of membrane potential on the GABA(A) receptor gating has not been elucidated. In the present study, the effect of membrane voltage on current responses elicited by ultrafast GABA applications was studied in cultured hippocampal neurons. The current to voltage relationship (I-V) for responses to saturating [GABA] (10 mM) showed an inward rectification (slope conductance at positive voltages was 0.62 +/- 0.05 of that at negative potentials). On the contrary, I-V for currents evoked by low [GABA] (1 microM) showed an outward rectification. The onset of currents elicited by saturating [GABA] was significantly accelerated at positive potentials. Analysis of currents evoked by prolonged applications of saturating [GABA] revealed that positive voltages significantly increased the rate and extent of desensitization. The onsets of current responses to non-saturating [GABA] were significantly accelerated at positive voltages indicating an enhancement of the binding rate. However, at low [GABA] at which the onset rate is expected to approach an asymptote set by opening/closing and unbinding rates, no significant modification of current onset by voltage was observed. Quantitative analysis based on model simulations indicated that the major effect of membrane depolarization was to increase the rates of binding, desensitization and of opening as well as to slightly reduce the rate of exit from desensitization. In conclusion, we provide evidence that membrane voltage affects the GABA(A) receptor microscopic gating.

  3. Pregabalin reduces the release of synaptic vesicles from cultured hippocampal neurons.

    Science.gov (United States)

    Micheva, Kristina D; Taylor, Charles P; Smith, Stephen J

    2006-08-01

    Pregabalin [S-[+]-3-isobutylGABA or (S)-3-(aminomethyl)-5-methylhexanoic acid, Lyrica] is an anticonvulsant and analgesic medication that is both structurally and pharmacologically related to gabapentin (Neurontin; Pfizer Inc., New York, NY). Previous studies have shown that pregabalin reduces the release of neurotransmitters in several in vitro preparations, although the molecular details of these effects are less clear. The present study was performed using living cultured rat hippocampal neurons with the synaptic vesicle fluorescent dye probe FM4-64 to determine details of the action of pregabalin to reduce neurotransmitter release. Our results indicate that pregabalin treatment, at concentrations that are therapeutically relevant, slightly but significantly reduces the emptying of neurotransmitter vesicles from presynaptic sites in living neurons. Dye release is reduced in both glutamic acid decarboxylase (GAD)-immunoreactive and GAD-negative (presumed glutamatergic) synaptic terminals. Furthermore, both calcium-dependent release and hyperosmotic (calcium-independent) dye release are reduced by pregabalin. The effects of pregabalin on dye release are masked in the presence of l-isoleucine, consistent with the fact that both of these compounds have a high binding affinity to the calcium channel alpha(2)-delta protein. The effect of pregabalin is not apparent in the presence of an N-methyl-d-aspartate (NMDA) antagonist [D(-)-2-amino-5-phosphonopentanoic acid], suggesting that pregabalin action depends on NMDA receptor activation. Finally, the action of pregabalin on dye release is most apparent before and early during a train of electrical stimuli when vesicle release preferentially involves the readily releasable pool.

  4. Biocompatibility of very small superparamagnetic iron oxide nanoparticles in murine organotypic hippocampal slice cultures and the role of microglia.

    Science.gov (United States)

    Pohland, Martin; Glumm, Robert; Wiekhorst, Frank; Kiwit, Jürgen; Glumm, Jana

    2017-01-01

    Superparamagnetic iron oxide nanoparticles (SPIO) are applied as contrast media for magnetic resonance imaging (MRI) and treatment of neurologic diseases despite the fact that important information concerning their local interactions is still lacking. Due to their small size, SPIO have great potential for magnetically labeling different cell populations, facilitating their MRI tracking in vivo. Before SPIO are applied, however, their effect on cell viability and tissue homoeostasis should be studied thoroughly. We have previously published data showing how citrate-coated very small superparamagnetic iron oxide particles (VSOP) affect primary microglia and neuron cell cultures as well as neuron-glia cocultures. To extend our knowledge of VSOP interactions on the three-dimensional multicellular level, we further examined the influence of two types of coated VSOP (R1 and R2) on murine organotypic hippocampal slice cultures. Our data show that 1) VSOP can penetrate deep tissue layers, 2) long-term VSOP-R2 treatment alters cell viability within the dentate gyrus, 3) during short-term incubation VSOP-R1 and VSOP-R2 comparably modify hippocampal cell viability, 4) VSOP treatment does not affect cytokine homeostasis, 5) microglial depletion decreases VSOP uptake, and 6) microglial depletion plus VSOP treatment increases hippocampal cell death during short-term incubation. These results are in line with our previous findings in cell coculture experiments regarding microglial protection of neurite branching. Thus, we have not only clarified the interaction between VSOP, slice culture, and microglia to a degree but also demonstrated that our model is a promising approach for screening nanoparticles to exclude potential cytotoxic effects.

  5. Biocompatibility of very small superparamagnetic iron oxide nanoparticles in murine organotypic hippocampal slice cultures and the role of microglia

    Science.gov (United States)

    Pohland, Martin; Glumm, Robert; Wiekhorst, Frank; Kiwit, Jürgen; Glumm, Jana

    2017-01-01

    Superparamagnetic iron oxide nanoparticles (SPIO) are applied as contrast media for magnetic resonance imaging (MRI) and treatment of neurologic diseases despite the fact that important information concerning their local interactions is still lacking. Due to their small size, SPIO have great potential for magnetically labeling different cell populations, facilitating their MRI tracking in vivo. Before SPIO are applied, however, their effect on cell viability and tissue homoeostasis should be studied thoroughly. We have previously published data showing how citrate-coated very small superparamagnetic iron oxide particles (VSOP) affect primary microglia and neuron cell cultures as well as neuron-glia cocultures. To extend our knowledge of VSOP interactions on the three-dimensional multicellular level, we further examined the influence of two types of coated VSOP (R1 and R2) on murine organotypic hippocampal slice cultures. Our data show that 1) VSOP can penetrate deep tissue layers, 2) long-term VSOP-R2 treatment alters cell viability within the dentate gyrus, 3) during short-term incubation VSOP-R1 and VSOP-R2 comparably modify hippocampal cell viability, 4) VSOP treatment does not affect cytokine homeostasis, 5) microglial depletion decreases VSOP uptake, and 6) microglial depletion plus VSOP treatment increases hippocampal cell death during short-term incubation. These results are in line with our previous findings in cell coculture experiments regarding microglial protection of neurite branching. Thus, we have not only clarified the interaction between VSOP, slice culture, and microglia to a degree but also demonstrated that our model is a promising approach for screening nanoparticles to exclude potential cytotoxic effects.

  6. Protective effects of aloperine on neonatal rat primary cultured hippocampal neurons injured by oxygen-glucose deprivation and reperfusion.

    Science.gov (United States)

    Ma, Ning-Tian; Zhou, Ru; Chang, Ren-Yuan; Hao, Yin-Ju; Ma, Lin; Jin, Shao-Ju; Du, Juan; Zheng, Jie; Zhao, Cheng-Jun; Niu, Yang; Sun, Tao; Li, Wei; Koike, Kazuo; Yu, Jian-Qiang; Li, Yu-Xiang

    2015-10-01

    Aloperine (ALO), one of the alkaloids isolated from Sophora alopecuroides L., is traditionally used for various diseases including neuronal disorders. This study investigated the protective effects of ALO on neonatal rat primary-cultured hippocampal neurons injured by oxygen-glucose deprivation and reperfusion (OGD/RP). Treatment with ALO (25, 50, and 100 mg/l) attenuated neuronal damage (p oxygen species and malondialdehyde production and enhanced the antioxidant enzymatic activities of catalase, superoxide dismutase, glutathione peroxidase and the total antioxidant capacity. The results suggested that ALO has significant neuroprotective effects that can be attributed to anti-oxidative stress.

  7. DIDS prevents ischemic membrane degradation in cultured hippocampal neurons by inhibiting matrix metalloproteinase release.

    Science.gov (United States)

    Pamenter, Matthew E; Ryu, Julie; Hua, Serena T; Perkins, Guy A; Mendiola, Vincent L; Gu, Xiang Q; Ellisman, Mark H; Haddad, Gabriel G

    2012-01-01

    During stroke, cells in the infarct core exhibit rapid failure of their permeability barriers, which releases ions and inflammatory molecules that are deleterious to nearby tissue (the penumbra). Plasma membrane degradation is key to penumbral spread and is mediated by matrix metalloproteinases (MMPs), which are released via vesicular exocytosis into the extracellular fluid in response to stress. DIDS (4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid) preserves membrane integrity in neurons challenged with an in vitro ischemic penumbral mimic (ischemic solution: IS) and we asked whether this action was mediated via inhibition of MMP activity. In cultured murine hippocampal neurons challenged with IS, intracellular proMMP-2 and -9 expression increased 4-10 fold and extracellular latent and active MMP isoform expression increased 2-22 fold. MMP-mediated extracellular gelatinolytic activity increased ∼20-50 fold, causing detachment of 32.1±4.5% of cells from the matrix and extensive plasma membrane degradation (>60% of cells took up vital dyes and >60% of plasma membranes were fragmented or blebbed). DIDS abolished cellular detachment and membrane degradation in neurons and the pathology-induced extracellular expression of latent and active MMPs. DIDS similarly inhibited extracellular MMP expression and cellular detachment induced by the pro-apoptotic agent staurosporine or the general proteinase agonist 4-aminophenylmercuric acetate (APMA). Conversely, DIDS-treatment did not impair stress-induced intracellular proMMP production, nor the intracellular cleavage of proMMP-2 to the active form, suggesting DIDS interferes with the vesicular extrusion of MMPs rather than directly inhibiting proteinase expression or activation. In support of this hypothesis, an antagonist of the V-type vesicular ATPase also inhibited extracellular MMP expression to a similar degree as DIDS. In addition, in a proteinase-independent model of vesicular exocytosis, DIDS prevented stimulus

  8. DIDS prevents ischemic membrane degradation in cultured hippocampal neurons by inhibiting matrix metalloproteinase release.

    Directory of Open Access Journals (Sweden)

    Matthew E Pamenter

    Full Text Available During stroke, cells in the infarct core exhibit rapid failure of their permeability barriers, which releases ions and inflammatory molecules that are deleterious to nearby tissue (the penumbra. Plasma membrane degradation is key to penumbral spread and is mediated by matrix metalloproteinases (MMPs, which are released via vesicular exocytosis into the extracellular fluid in response to stress. DIDS (4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid preserves membrane integrity in neurons challenged with an in vitro ischemic penumbral mimic (ischemic solution: IS and we asked whether this action was mediated via inhibition of MMP activity. In cultured murine hippocampal neurons challenged with IS, intracellular proMMP-2 and -9 expression increased 4-10 fold and extracellular latent and active MMP isoform expression increased 2-22 fold. MMP-mediated extracellular gelatinolytic activity increased ∼20-50 fold, causing detachment of 32.1±4.5% of cells from the matrix and extensive plasma membrane degradation (>60% of cells took up vital dyes and >60% of plasma membranes were fragmented or blebbed. DIDS abolished cellular detachment and membrane degradation in neurons and the pathology-induced extracellular expression of latent and active MMPs. DIDS similarly inhibited extracellular MMP expression and cellular detachment induced by the pro-apoptotic agent staurosporine or the general proteinase agonist 4-aminophenylmercuric acetate (APMA. Conversely, DIDS-treatment did not impair stress-induced intracellular proMMP production, nor the intracellular cleavage of proMMP-2 to the active form, suggesting DIDS interferes with the vesicular extrusion of MMPs rather than directly inhibiting proteinase expression or activation. In support of this hypothesis, an antagonist of the V-type vesicular ATPase also inhibited extracellular MMP expression to a similar degree as DIDS. In addition, in a proteinase-independent model of vesicular exocytosis, DIDS

  9. Neuroprotective effects of the AMPA antagonist PNQX in oxygen-glucose deprivation in mouse hippocampal slice cultures and global cerebral ischemia in gerbils

    DEFF Research Database (Denmark)

    Montero, Maria; Nielsen, Marianne; Rønn, Lars Christian B;

    2007-01-01

    PNQX (9-methyl-amino-6-nitro-hexahydro-benzo(F)quinoxalinedione) is a selective AMPA antagonist with demonstrated neuroprotective effects in focal ischemia in rats. Here we report corresponding effects in mouse hippocampal slice cultures subjected to oxygen and glucose deprivation (OGD......) and in transient global cerebral ischemia in gerbils. For in vitro studies, hippocampal slice cultures derived from 7-day-old mice and grown for 14 days, were submersed in oxygen-glucose deprived medium for 30 min and exposed to PNQX for 24 h, starting together with OGD, immediately after OGD, or 2 h after OGD...... ischemia in gerbils in vivo and oxygen-glucose deprivation in mouse hippocampal slice cultures....

  10. Developmental and Activity-Dependent miRNA Expression Profiling in Primary Hippocampal Neuron Cultures

    NARCIS (Netherlands)

    M. van Spronsen (Myrrhe); E.Y. van Battum (Eljo); M. Kuijpers (Marijn); V.R. Vangoor (Vamshidhar); M.L. Rietman (M. Liset); J. Pothof (Joris); L.F. Gumy (Laura); W.F.J. van IJcken (Wilfred); A.S. Akhmanova (Anna); R.J. Pasterkamp (Jeroen); C.C. Hoogenraad (Casper)

    2013-01-01

    textabstractMicroRNAs (miRNAs) are evolutionarily conserved non-coding RNAs of ∼22 nucleotides that regulate gene expression at the level of translation and play vital roles in hippocampal neuron development, function and plasticity. Here, we performed a systematic and in-depth analysis of miRNA exp

  11. Metabolism of dehydroepiandrosterone by rat hippocampal cells in culture: possible role of aromatization and 7-hydroxylation in neuroprotection.

    Science.gov (United States)

    Jellinck, P H; Lee, S J; McEwen, B S

    2001-10-01

    The rate of metabolism of the multifunctional neurosteroid, dehydroepiandrosterone (DHEA), by embryonic rat hippocampal cells maintained in culture was compared to that of 4-androstenedione (AD), the immediate precursor of estrone (E1). The experiments were carried out to assess the relative contribution of DHEA, its 7-hydroxylated metabolites and estrogen on their reported effects on memory and neuroprotection. The 3H-labeled steroids of high specific radioactivity were incubated for 1, 8, 24 and 48 h and the putative metabolites extracted from the culture medium with acetone-ethyl acetate before separation by TLC for radioassay. [3H]DHEA (2.0 ng/5x10(5) cells) yielded primarily the 7alpha- and 7beta-hydroxylated steroids in an almost equal ratio under conditions that resembled those used by others to study the protection of neurons by hippocampal astrocytes against excitatory amino acid-induced toxicity. The rate of conversion of DHEA to AD, and particularly to E1, was much lower. With [3H]AD as substrate, significant aromatization to estrogen occurred only after 24 h when most of [3H]DHEA had already been converted to its 7-hydroxylated products and the hydroxylase and aromatase systems would no longer be competing for the same coenzyme (NADPH). The hippocampal cells were still viable after 48 h of incubation with the steroids and were able to oxidize estradiol (E2) to E1 and reduce E1 to E2 and AD to testosterone (T). It is suggested that 7alpha- and 7beta-OHDHEA, the main metabolites formed in the rat hippocampus, might be responsible for some of the functions previously ascribed to estrogens in the brain and the reasons for this proposal are discussed.

  12. Serotonin (5-HT) regulates neurite outgrowth through 5-HT1A and 5-HT7 receptors in cultured hippocampal neurons.

    Science.gov (United States)

    Rojas, Paulina S; Neira, David; Muñoz, Mauricio; Lavandero, Sergio; Fiedler, Jenny L

    2014-08-01

    Serotonin (5-HT) production and expression of 5-HT receptors (5-HTRs) occur early during prenatal development. Recent evidence suggests that, in addition to its classical role as a neurotransmitter, 5-HT regulates neuronal connectivity during mammalian development by modulating cell migration and neuronal cytoarchitecture. Given the variety of 5-HTRs, researchers have had difficulty clarifying the specific role of each receptor subtype in brain development. Signalling mediated by the G-protein-coupled 5-HT1A R and 5-HT7 R, however, has been associated with neuronal plasticity. Thus, we hypothesized that 5-HT promotes neurite outgrowth through 5-HT1A R and 5-HT7 R. The involvement of 5-HT1A R and 5-HT7 R in the morphology of rat hippocampal neurons was evaluated by treating primary cultures at 2 days in vitro with 5-HT and specific antagonists for 5-HT1A R and 5-HT7 R (WAY-100635 and SB269970, respectively). The stimulation of hippocampal neurons with 100 nM 5-HT for 24 hr produced no effect on either the number or the length of primary neurites. Nonetheless, after 5HT7 R was blocked, the addition of 5-HT increased the number of primary neurites, suggesting that 5HT7 R could inhibit neuritogenesis. In contrast, 5-HT induced secondary neurite outgrowth, an effect inhibited by 1 μM WAY-100635 or SB269970. These results suggest that both serotonergic receptors participate in secondary neurite outgrowth. We conclude that 5-HT1A R and 5-HT7 R regulate neuronal morphology in primary hippocampal cultures by promoting secondary neurite outgrowth.

  13. Formaldehyde increases intracellular calcium concentration in primary cultured hippocampal neurons partly through NMDA receptors and T-type calcium channels

    Institute of Scientific and Technical Information of China (English)

    Ye-Nan Chi; Xu Zhang; Jie Cai; Feng-Yu Liu; Guo-Gang Xing; You Wan

    2012-01-01

    Objective Formaldehyde at high concentrations is a contributor to air pollution.It is also an endogenous metabolic product in cells,and when beyond physiological concentrations,has pathological effects on neurons.Formaldehyde induces mis-folding and aggregation of neuronal tau protein,hippocampal neuronal apoptosis,cognitive impairment and loss of memory functions,as well as excitation of peripheral nociceptive neurons in cancer pain models.Intracellular calcium ([Ca2+]i) is an important intracellular messenger,and plays a key role in many pathological processes.The present study aimed to investigate the effect of formaldehyde on [Ca2+]i and the possible involvement of N-methyl-D-aspartate receptors (NMDARs) and T-type Ca2+ channels on the cell membrane.Methods Using primary cultured hippocampal neurons as a model,changes of [Ca2+]i in the presence of formaldehyde at a low concentration were detected by confocal laser scanning microscopy.Results Formaldehyde at 1 mmol/L approximately doubled [Ca2+]i.(2R)-amino-5-phosphonopentanoate (AP5,25 μtmol/L,an NMDAR antagonist) and mibefradil (MIB,1 μtmol/L,a T-type Ca2+ channel blocker),given 5 min after formaldehyde perfusion,each partly inhibited the formaldehyde-induced increase of [Ca2+]i,and this inhibitory effect was reinforced by combined application of AP5 and MIB.When applied 3 min before formaldehyde perfusion,AP5 (even at 50 μmol/L) did not inhibit the formaldehyde-induced increase of [Ca2+]i,but MIB (1 μmol/L) significantly inhibited this increase by 70%.Conclusion These results suggest that formaldehyde at a low concentration increases [Ca2+]i in cultured hippocampal neurons; NMDARs and T-type Ca2+ channels may be involved in this process.

  14. Addition of glutamate to serum free culture promotes recovery of electrical activity in adult hippocampal neurons in vitro

    Science.gov (United States)

    Edwards, Darin; Das, Mainak; Molnar, Peter; Hickman, James J.

    2010-01-01

    A long-term cell culture system utilizing normal adult hippocampal neurons would represent an important tool that could be useful in research on the mature brain, neurological disorders and age-related neurological diseases. Historically, in vitro neuronal systems are derived from embryonic rather than mature brain tissue, a practice predicated upon difficulties in supporting regeneration, functional recovery and long-term survival of adult neurons in vitro. A few studies have shown that neurons derived from the hippocampal tissue of adult rats can survive and regenerate in vitro under serum-free conditions. However, while the adult neurons regenerated morphologically under these conditions, both the electrical activity characteristic of in vivo neurons as well as long-term neuronal survival was not consistently recovered in vitro. In this study, we report on the development of a defined culture system with the ability to support functional recovery and long-term survival of adult rat hippocampal neurons. In this system, the cell-adhesive substrate, N-1 [3-(trimethoxysilyl) propyl]-diethylenetriamine, supported neuronal attachment, regeneration, and long-term survival of adult neurons for more than 80 days in vitro. Additionally, the excitatory neurotransmitter glutamate, applied at 25 μM for 1 to 7 days after morphological neuronal regeneration in vitro, enabled full recovery of neuronal electrical activity. This low concentration of glutamate promoted the recovery of neuronal electrical activity but with minimal excitotoxicity. These improvements allowed electrically active adult neurons to survive in vitro for several months, providing a stable test-bed for the long-term study of regeneration in adult derived neuronal systems, especially for traumatic brain injury (TBI). PMID:20452373

  15. Addition of glutamate to serum-free culture promotes recovery of electrical activity in adult hippocampal neurons in vitro.

    Science.gov (United States)

    Edwards, Darin; Das, Mainak; Molnar, Peter; Hickman, James J

    2010-07-15

    A long-term cell culture system utilizing normal adult hippocampal neurons would represent an important tool that could be useful in research on the mature brain, neurological disorders and age-related neurological diseases. Historically, in vitro neuronal systems are derived from embryonic rather than mature brain tissue, a practice predicated upon difficulties in supporting regeneration, functional recovery and long-term survival of adult neurons in vitro. A few studies have shown that neurons derived from the hippocampal tissue of adult rats can survive and regenerate in vitro under serum-free conditions. However, while the adult neurons regenerated morphologically under these conditions, both the electrical activity characteristic of in vivo neurons as well as long-term neuronal survival was not consistently recovered in vitro. In this study, we report on the development of a defined culture system with the ability to support functional recovery and long-term survival of adult rat hippocampal neurons. In this system, the cell-adhesive substrate, N-1 [3-(trimethoxysilyl) propyl]-diethylenetriamine, supported neuronal attachment, regeneration, and long-term survival of adult neurons for more than 80 days in vitro. Additionally, the excitatory neurotransmitter glutamate, applied at 25muM for 1-7 days after morphological neuronal regeneration in vitro, enabled full recovery of neuronal electrical activity. This low concentration of glutamate promoted the recovery of neuronal electrical activity but with minimal excitotoxicity. These improvements allowed electrically active adult neurons to survive in vitro for several months, providing a stable test-bed for the long-term study of regeneration in adult-derived neuronal systems, especially for traumatic brain injury (TBI). Copyright 2010 Elsevier B.V. All rights reserved.

  16. Enhancement of dendritic branching in cultured hippocampal neurons by 17beta-estradiol is mediated by nitric oxide.

    Science.gov (United States)

    Audesirk, T; Cabell, L; Kern, M; Audesirk, G

    2003-06-01

    Both 17beta-estradiol (E2) and nitric oxide (NO) are important in neuronal development, learning and memory, and age-related memory changes. There is growing evidence that a number of estrogen receptor-mediated effects of estradiol utilize nitric oxide as an intermediary. The role of estradiol in hippocampal neuronal differentiation and function has particular implications for learning and memory. Low levels of estradiol (10nM) significantly increase dendritic branching in cultured embryonic rat hippocampal neurons (158% of control). This study investigates the hypothesis that the estrogen-stimulated increase in dendritic branching is mediated by nitric oxide. We found that nitric oxide donors also produce significantly increased dendritic branching S-nitroso-N-acetylpenicillamine (SNAP: 119%; 2,2'-(hydroxynitrosohydrazino)bis-ethanamine (NOC-18): 128% of control). We then determined that the increases in dendritic branching stimulated by estradiol or by a nitric oxide donor were both blocked by an inhibitor of guanylyl cyclase. Dendritic branching was also stimulated by a cell permeable analog of cyclic guanosine monophosphate (dibutyryl-cGMP: 173% of control). Estradiol-stimulated dendritic branching was reversed by the nitric oxide scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethyl imidazoline-1-oxyl 3-oxide (carboxy-PTIO). This study provides evidence that estradiol influences the development of embryonic hippocampal neurons in culture by increasing the production of nitric oxide or by increasing the sensitivity of the neurons to nitric oxide. Nitric oxide in turn stimulates dendritic branching via activation of guanylyl cyclase.

  17. Potentiation by histamine of synaptically mediated excitotoxicity in cultured hippocampal neurones: a possible role for mast cells.

    Science.gov (United States)

    Skaper, S D; Facci, L; Kee, W J; Strijbos, P J

    2001-01-01

    Excessive glutamatergic neurotransmission, particularly when mediated by the N:-methyl-D-aspartate (NMDA) subtype of glutamate receptor, is thought to underlie neuronal death in a number of neurological disorders. Histamine has been reported to potentiate NMDA receptor-mediated events under a variety of conditions. In the present study we have utilized primary hippocampal neurone cultures to investigate the effect of mast cell-derived, as well as exogenously applied, histamine on neurotoxicity evoked by excessive synaptic activity. Exposure of mature cultures for 15 min to an Mg(2+)-free/glycine-containing buffer to trigger synaptic transmission through NMDA receptors, caused a 30-35% neuronal loss over 24 h. When co-cultured with hippocampal neurones, activated mast cells increased excitotoxic injury to 60%, an effect that was abolished in the presence of histaminase. Similarly, addition of histamine during magnesium deprivation produced a concentration-dependent potentiation (+ 60%; EC(50) : 5 microM) of neuronal death which was inhibited by sodium channel blockers and NMDA receptor antagonists, although this effect did not involve known histamine receptors. The histamine effect was further potentiated by acidification of the culture medium. Cultures 'preconditioned' by sublethal (5 min) Mg(2+) deprivation exhibited less neuronal death than controls when exposed to a more severe insult. NMDA receptor activation and the extracellular regulated kinase cascade were required for preconditioning neuroprotection. The finding that histamine potentiates NMDA receptor-mediated excitotoxicity may have important implications for our understanding of conditions where enhanced glutamatergic neurotransmission is observed in conjunction with tissue acidification, such as cerebral ischaemia and epilepsy.

  18. Urban Public Health: Is There a Pyramid?

    Science.gov (United States)

    Su, Meirong; Chen, Bin; Yang, Zhifeng; Cai, Yanpeng; Wang, Jiao

    2013-01-01

    Early ecologists identified a pyramidal trophic structure in terms of number, biomass and energy transfer. In 1943, the psychologist Maslow put forward a pyramid model to describe layers of human needs. It is indicated that the pyramid principle is universally applicable in natural, humanistic and social disciplines. Here, we report that a pyramid structure also exists in urban public health (UPH). Based on 18 indicators, the UPH states of four cities (Beijing, Tokyo, New York, and London) are compared from the point of view of five aspects, namely physical health, living conditions, social security, environmental quality, and education and culture. A pyramid structure was found in each city when focusing on 2000–2009 data. The pyramid of Beijing is relatively similar to that of Tokyo, and the pyramids of New York and London are similar to each other. A general development trend in UPH is proposed and represented by different pyramid modes. As a basic conjecture, the UPH pyramid model can be verified and developed with data of more cities over a longer period, and be used to promote healthy urban development. PMID:23358233

  19. Urban Public Health: Is There a Pyramid?

    Directory of Open Access Journals (Sweden)

    Meirong Su

    2013-01-01

    Full Text Available Early ecologists identified a pyramidal trophic structure in terms of number, biomass and energy transfer. In 1943, the psychologist Maslow put forward a pyramid model to describe layers of human needs. It is indicated that the pyramid principle is universally applicable in natural, humanistic and social disciplines. Here, we report that a pyramid structure also exists in urban public health (UPH. Based on 18 indicators, the UPH states of four cities (Beijing, Tokyo, New York, and London are compared from the point of view of five aspects, namely physical health, living conditions, social security, environmental quality, and education and culture. A pyramid structure was found in each city when focusing on 2000–2009 data. The pyramid of Beijing is relatively similar to that of Tokyo, and the pyramids of New York and London are similar to each other. A general development trend in UPH is proposed and represented by different pyramid modes. As a basic conjecture, the UPH pyramid model can be verified and developed with data of more cities over a longer period, and be used to promote healthy urban development.

  20. Urban public health: is there a pyramid?

    Science.gov (United States)

    Su, Meirong; Chen, Bin; Yang, Zhifeng; Cai, Yanpeng; Wang, Jiao

    2013-01-28

    Early ecologists identified a pyramidal trophic structure in terms of number, biomass and energy transfer. In 1943, the psychologist Maslow put forward a pyramid model to describe layers of human needs. It is indicated that the pyramid principle is universally applicable in natural, humanistic and social disciplines. Here, we report that a pyramid structure also exists in urban public health (UPH). Based on 18 indicators, the UPH states of four cities (Beijing, Tokyo, New York, and London) are compared from the point of view of five aspects, namely physical health, living conditions, social security, environmental quality, and education and culture. A pyramid structure was found in each city when focusing on 2000-2009 data. The pyramid of Beijing is relatively similar to that of Tokyo, and the pyramids of New York and London are similar to each other. A general development trend in UPH is proposed and represented by different pyramid modes. As a basic conjecture, the UPH pyramid model can be verified and developed with data of more cities over a longer period, and be used to promote healthy urban development.

  1. Membrane voltage differently affects mIPSCs and current responses recorded from somatic excised patches in rat hippocampal cultures.

    Science.gov (United States)

    Pytel, Maria; Mozrzymas, Jerzy W

    2006-01-30

    Recent analysis of current responses to exogenous GABA applications recorded from excised patches indicated that membrane voltage affected the GABAA receptor gating mainly by altering desensitization and binding [M. Pytel, K. Mercik, J.W. Mozrzymas, Membrane voltage modulates the GABAA receptor gating in cultured rat hippocampal neurons, Neuropharmacology, in press]. In order investigate the impact of such voltage effect on GABAA receptors in conditions of synaptic transmission, mIPSCs and current responses to rapid GABA applications were recorded from the same culture of rat hippocampal neurons. We found that I-V relationship for mIPSCs amplitudes showed a clear outward rectification while for current responses an inward rectification was seen, except for very low GABA concentrations. A clear shift in amplitude cumulative distributions indicated that outward rectification resulted from the voltage effect on the majority of mIPSCs. Moreover, the decaying phase of mIPSCs was clearly slowed down at positive voltages and this effect was represented by a shift in cumulative distributions of weighted decaying time constants. In contrast, deactivation of current responses was only slightly affected by membrane depolarization. These data indicate that the mechanisms whereby the membrane voltage modulates synaptic and extrasynaptic receptors are qualitatively different but the mechanism underlying this difference is not clear.

  2. Protection from neuronal damage induced by combined oxygen and glucose deprivation in organotypic hippocampal cultures by glutamate receptor antagonists.

    Science.gov (United States)

    Strasser, U; Fischer, G

    1995-07-31

    Organotypic hippocampal cultures were exposed to defined periods (30 and 60 min) of combined oxygen and glucose deprivation, mimicking transient ischemic conditions. The involvement of different glutamate receptors in individual hippocampal subfields (CA1, CA3 and dentate gyrus) was studied using antagonists of NMDA (dizocilpine) and AMPA/kainate receptors (CNQX and GYKI 52466). Staining with the fluorescent dye propidium iodide (PI) allowed detection of damaged cells. For quantitative determination of neuronal damage, fluorescence intensity was measured after a 22 h recovery period and was related to maximal fluorescence intensity measured after fixation and PI restaining of the cultures at the end of the experiment. Dizocilpine (10 microM), CNQX (100 microM) and GYKI 52466 (100 microM) provided complete protection in CA1, CA3 and dentate gyrus following the moderate ischemic insult, when the antagonists were present permanently. This indicates that none of the ionotropic glutamate receptor subtypes dominated toxicity in the most sensitive subpopulation of neurons. When applied only during the recovery period protection with dizocilpine (10 microM) or CNQX (100 microM) was drastically reduced by about 60% in the most sensitive area (CA1), but only slightly by 15% in CA3. Therefore the onset of irreversible damage seems to occur earlier in CA1 than in CA3. Blockade of AMPA/kainate receptors by GYKI 52466 (100 microM) offered no neuroprotection if the compound was applied only during the recovery period.(ABSTRACT TRUNCATED AT 250 WORDS)

  3. Reduced Hyperpolarization-Activated Current Contributes to Enhanced Intrinsic Excitability in Cultured Hippocampal Neurons from PrP(-/-) Mice.

    Science.gov (United States)

    Fan, Jing; Stemkowski, Patrick L; Gandini, Maria A; Black, Stefanie A; Zhang, Zizhen; Souza, Ivana A; Chen, Lina; Zamponi, Gerald W

    2016-01-01

    Genetic ablation of cellular prion protein (PrP(C)) has been linked to increased neuronal excitability and synaptic activity in the hippocampus. We have previously shown that synaptic activity in hippocampi of PrP-null mice is increased due to enhanced N-methyl-D-aspartate receptor (NMDAR) function. Here, we focused on the effect of PRNP gene knock-out (KO) on intrinsic neuronal excitability, and in particular, the underlying ionic mechanism in hippocampal neurons cultured from P0 mouse pups. We found that the absence of PrP(C) profoundly affected the firing properties of cultured hippocampal neurons in the presence of synaptic blockers. The membrane impedance was greater in PrP-null neurons, and this difference was abolished by the hyperpolarization-activated cyclic nucleotide-gated (HCN) channel blocker ZD7288 (100 μM). HCN channel activity appeared to be functionally regulated by PrP(C). The amplitude of voltage sag, a characteristic of activating HCN channel current (I h), was decreased in null mice. Moreover, I h peak current was reduced, along with a hyperpolarizing shift in activation gating and slower kinetics. However, neither HCN1 nor HCN2 formed a biochemical complex with PrP(C). These results suggest that the absence of PrP downregulates the activity of HCN channels through activation of a cell signaling pathway rather than through direct interactions. This in turn contributes to an increase in membrane impedance to potentiate neuronal excitability.

  4. The potential of apolipoprotein E4 to act as a substrate for primary cultures of hippocampal neurons.

    Science.gov (United States)

    Kim, Kwang-Min; Vicenty, Janice; Palmore, G Tayhas R

    2013-04-01

    The E4 isoform of apolipoprotein (apoE4) is known to be a major risk factor for Alzheimer's Disease (AD). Previous in vitro studies have shown apoE4 to have a negative effect on neuronal outgrowth when incubated with lipids. The effect of apoE4 itself on the development of neurons from the central nervous system (CNS), however, has not been well characterized. Consequently, apoE4 alone has not been pursued as a substrate for neuronal cultures. In this study, the effect of surface-bound apoE4 on developmental features of rat hippocampal neurons was examined. We show that apoE4 substrates elicit significantly enhanced values in all developmental features at day 2 of culture when compared to laminin (LN) substrates, which is the current substrate-of-choice for neuronal cultures. Interestingly, the adhesion of hippocampal neurons was found to be significantly lower on LN substrates than on glass substrates, but the axon lengths on both substrates were similar. In addition, this study demonstrates that the adhesion- and growth-enhancing effects of apoE4 substrates are not mediated by heparan sulfate proteoglycans (HSPGs), proteins that have been indicated to function as receptors or co-receptors for apoE4. In the absence of lipids, apoE4 appears to use an unknown pathway for up-regulating neuronal adhesion and neurite outgrowth. Our results indicate that apoE4 is better than LN as a substrate for primary cultures of CNS neurons and should be considered in the design of tissue engineered CNS.

  5. Pyramid Comet Sampler Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Based on the sampling requirements, we propose an Inverted Pyramid sampling system. Each face of the pyramid includes a cutting blade which is independently actuated...

  6. Long-lasting changes in DNA methylation following short-term hypoxic exposure in primary hippocampal neuronal cultures.

    Directory of Open Access Journals (Sweden)

    Iain Hartley

    Full Text Available While the effects of hypoxia on gene expression have been investigated in the CNS to some extent, we currently do not know what role epigenetics plays in the transcription of many genes during such hypoxic stress. To start understanding the role of epigenetic changes during hypoxia, we investigated the long-term effect of hypoxia on gene expression and DNA methylation in hippocampal neuronal cells. Primary murine hippocampal neuronal cells were cultured for 7 days. Hypoxic stress of 1% O2, 5% CO2 for 24 hours was applied on Day 3, conditions we found to maximize cellular hypoxic stress response without inducing cell death. Cells were returned to normoxia for 4 days following the period of hypoxic stress. On Day 7, Methyl-Sensitive Cut Counting (MSCC was used to identify a genome-wide methylation profile of the hippocampal cell lines to assess methylation changes resulting from hypoxia. RNA-Seq was also done on Day 7 to analyze changes in gene transcription. Phenotypic analysis showed that neuronal processes were significantly shorter after 1 day of hypoxia, but there was a catch-up growth of these processes after return to normoxia. Transcriptome profiling using RNA-Seq revealed 369 differentially expressed genes with 225 being upregulated, many of which form networks shown to affect CNS development and function. Importantly, the expression level of 59 genes could be correlated to the changes in DNA methylation in their promoter regions. CpG islands, in particular, had a strong tendency to remain hypomethylated long after hypoxic stress was removed. From this study, we conclude that short-term, sub-lethal hypoxia results in long-lasting changes to genome wide DNA methylation status and that some of these changes can be highly correlated with transcriptional modulation in a number of genes involved in functional pathways that have been previously implicated in neural growth and development.

  7. Cell surface area regulation in neurons in hippocampal slice cultures is resistant to oxygen-glucose deprivation

    Directory of Open Access Journals (Sweden)

    Natalya Shulyakova

    2010-09-01

    Full Text Available Natalya Shulyakova1,2, Jamie Fong2, Diana Diec2, Adrian Nahirny1,2, Linda R Mills1,21Department of Physiology, University of Toronto, Toronto, ON, Canada, M5T 2S8; 2Toronto Western Hospital Research Institute, University Health Network, 11-430, 399 Bathurst St, Toronto, ON, Canada, M5T 2S8Background: Neurons swell in response to a variety of insults. The capacity to recover, ie, to shrink, is critical for neuronal function and survival. Studies on dissociated neurons have shown that during swelling and shrinking, neurons reorganize their plasma membrane; as neurons swell, in response to hypo-osmotic media, the bilayer area increases. Upon restoration of normo-osmotic media, neurons shrink, forming transient invaginations of the plasma membrane known as vacuole-like dilations (VLDs, to accommodate the decrease in the bilayer.Methods: Here we used confocal microscopy to monitor neuronal swelling and shrinking in the three-dimensional (3D environment of post-natal rat hippocampal slice cultures. To label neurons, we used biolistic transfection, to introduce enhanced green fluorescent protein (eGFP targeted to the cytoplasm; and a membrane targeted GFP (lckGFP, targeted to the plasma membrane.Results: Neurons in slice cultures swelled and shrank in response to hypo-osmotic to normo-osmotic media changes. Oxygen-glucose deprivation (OGD caused sustained neuronal swelling; after reperfusion, some neurons recovered but in others, VLD recovery was stalled. OGD did not impair neuronal capacity to recover from a subsequent osmotic challenge.Conclusion: These results suggest cell surface area regulation (SAR is an intrinsic property of neurons, and that neuronal capacity for SAR may play an important role in the brain’s response to ischemic insults.Keywords: neurons, swelling, ischemia, cell surface area, hippocampal slice culture

  8. Lead Can Inhibit NMDA-, K+-, QA/KA-Induced Increases in Intracellular Free Ca2+ in Cultured Rat Hippocampal Neurons

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Objective To examine the effects of Pb2+ on N-methyl-D-aspartate (NMDA)-, K+- and quisqualate(QA)/kainite(KA)-induced increases in intracellular free calcium concentration ([Ca2+]i) in cultured fetal rat hippocampal neurons in order to explain the cognitive and learning deficits produced by this heavy metal. Methods Laser scanning confocal microscopy was used. Results The results clearly demonstrated that adding Pb2+ before or after NMDA/glycine stimulation selectively inhibited the stimulated increases in [Ca2+]i in a concentration-dependent manner. In contrast, Pb2+ treatment did not markedly affect increases in [Ca2+]i induced by an admixture of QA and KA. The minimal inhibitory effect of Pb2+ occurred at 1 μ mol/L, and more than seventy percent abolition of the NMDA-stimulated increase in [Ca2+]iwas observed at 100 μmol/L Pb2+. Evaluation of pb2+-induced increase in [Ca2+]i response to elevating extracellular concentrations of NMDA, glycine or calcium revealed that Pb2+ was a noncompetitive antagonist of both NMDA and glycine, and a competitive antagonist of Ca2+ at NMDA receptor channels. In addition, Pb2+ inhibited depolarization-evoked increases in [Ca2+]i mediated by K+ stimulation (30 μmol/L), indicating that Pb2+ also depressed the voltage-dependent calcium channels. Also, the results showed that Pb2+ appeared to be able to elevate the resting levels of [Ca2+]i in cultured neurons, implying a reason for pb2+-enhanced spontaneous release of several neurotransmitters reported in several previous studies. Conclusion Lead can inhibit NMDA-, K+-, QA/KA-inducod increases in intracellular [Ca2+]i in cultured hippocampal neurons.

  9. Role of the Proteasome in Excitotoxicity-Induced Cleavage of Glutamic Acid Decarboxylase in Cultured Hippocampal Neurons

    Science.gov (United States)

    Armelão, Mário; Herrmann, Dennis; Pimentel, Diogo O.; Leal, Graciano; Caldeira, Margarida V.; Bahr, Ben A.; Bengtson, Mário; Almeida, Ramiro D.; Duarte, Carlos B.

    2010-01-01

    Glutamic acid decarboxylase is responsible for synthesizing GABA, the major inhibitory neurotransmitter, and exists in two isoforms—GAD65 and GAD67. The enzyme is cleaved under excitotoxic conditions, but the mechanisms involved and the functional consequences are not fully elucidated. We found that excitotoxic stimulation of cultured hippocampal neurons with glutamate leads to a time-dependent cleavage of GAD65 and GAD67 in the N-terminal region of the proteins, and decrease the corresponding mRNAs. The cleavage of GAD67 was sensitive to the proteasome inhibitors MG132, YU102 and lactacystin, and was also abrogated by the E1 ubiquitin ligase inhibitor UBEI-41. In contrast, MG132 and UBEI-41 were the only inhibitors tested that showed an effect on GAD65 cleavage. Excitotoxic stimulation with glutamate also increased the amount of GAD captured in experiments where ubiquitinated proteins and their binding partners were isolated. However, no evidences were found for direct GADs ubiquitination in cultured hippocampal neurons, and recombinant GAD65 was not cleaved by purified 20S or 26S proteasome preparations. Since calpains, a group of calcium activated proteases, play a key role in GAD65/67 cleavage under excitotoxic conditions the results suggest that GADs are cleaved after ubiquitination and degradation of an unknown binding partner by the proteasome. The characteristic punctate distribution of GAD65 along neurites of differentiated cultured hippocampal neurons was significantly reduced after excitotoxic injury, and the total GAD activity measured in extracts from the cerebellum or cerebral cortex at 24h postmortem (when there is a partial cleavage of GADs) was also decreased. The results show a role of the UPS in the cleavage of GAD65/67 and point out the deregulation of GADs under excitotoxic conditions, which is likely to affect GABAergic neurotransmission. This is the first time that the UPS has been implicated in the events triggered during excitotoxicity

  10. Role of the proteasome in excitotoxicity-induced cleavage of glutamic acid decarboxylase in cultured hippocampal neurons.

    Directory of Open Access Journals (Sweden)

    Márcio S Baptista

    Full Text Available Glutamic acid decarboxylase is responsible for synthesizing GABA, the major inhibitory neurotransmitter, and exists in two isoforms--GAD65 and GAD67. The enzyme is cleaved under excitotoxic conditions, but the mechanisms involved and the functional consequences are not fully elucidated. We found that excitotoxic stimulation of cultured hippocampal neurons with glutamate leads to a time-dependent cleavage of GAD65 and GAD67 in the N-terminal region of the proteins, and decrease the corresponding mRNAs. The cleavage of GAD67 was sensitive to the proteasome inhibitors MG132, YU102 and lactacystin, and was also abrogated by the E1 ubiquitin ligase inhibitor UBEI-41. In contrast, MG132 and UBEI-41 were the only inhibitors tested that showed an effect on GAD65 cleavage. Excitotoxic stimulation with glutamate also increased the amount of GAD captured in experiments where ubiquitinated proteins and their binding partners were isolated. However, no evidences were found for direct GADs ubiquitination in cultured hippocampal neurons, and recombinant GAD65 was not cleaved by purified 20S or 26S proteasome preparations. Since calpains, a group of calcium activated proteases, play a key role in GAD65/67 cleavage under excitotoxic conditions the results suggest that GADs are cleaved after ubiquitination and degradation of an unknown binding partner by the proteasome. The characteristic punctate distribution of GAD65 along neurites of differentiated cultured hippocampal neurons was significantly reduced after excitotoxic injury, and the total GAD activity measured in extracts from the cerebellum or cerebral cortex at 24h postmortem (when there is a partial cleavage of GADs was also decreased. The results show a role of the UPS in the cleavage of GAD65/67 and point out the deregulation of GADs under excitotoxic conditions, which is likely to affect GABAergic neurotransmission. This is the first time that the UPS has been implicated in the events triggered during

  11. Afadin regulates puncta adherentia junction formation and presynaptic differentiation in hippocampal neurons.

    Directory of Open Access Journals (Sweden)

    Daisaku Toyoshima

    Full Text Available The formation and remodeling of mossy fiber-CA3 pyramidal cell synapses in the stratum lucidum of the hippocampus are implicated in the cellular basis of learning and memory. Afadin and its binding cell adhesion molecules, nectin-1 and nectin-3, together with N-cadherin, are concentrated at puncta adherentia junctions (PAJs in these synapses. Here, we investigated the roles of afadin in PAJ formation and presynaptic differentiation in mossy fiber-CA3 pyramidal cell synapses. At these synapses in the mice in which the afadin gene was conditionally inactivated before synaptogenesis by using nestin-Cre mice, the immunofluorescence signals for the PAJ components, nectin-1, nectin-3 and N-cadherin, disappeared almost completely, while those for the presynaptic components, VGLUT1 and bassoon, were markedly decreased. In addition, these signals were significantly decreased in cultured afadin-deficient hippocampal neurons. Furthermore, the interevent interval of miniature excitatory postsynaptic currents was prolonged in the cultured afadin-deficient hippocampal neurons compared with control neurons, indicating that presynaptic functions were suppressed or a number of synapse was reduced in the afadin-deficient neurons. Analyses of presynaptic vesicle recycling and paired recordings revealed that the cultured afadin-deficient neurons showed impaired presynaptic functions. These results indicate that afadin regulates both PAJ formation and presynaptic differentiation in most mossy fiber-CA3 pyramidal cell synapses, while in a considerable population of these neurons, afadin regulates only PAJ formation but not presynaptic differentiation.

  12. Afadin Regulates Puncta Adherentia Junction Formation and Presynaptic Differentiation in Hippocampal Neurons

    Science.gov (United States)

    Toyoshima, Daisaku; Mandai, Kenji; Maruo, Tomohiko; Supriyanto, Irwan; Togashi, Hideru; Inoue, Takahito; Mori, Masahiro; Takai, Yoshimi

    2014-01-01

    The formation and remodeling of mossy fiber-CA3 pyramidal cell synapses in the stratum lucidum of the hippocampus are implicated in the cellular basis of learning and memory. Afadin and its binding cell adhesion molecules, nectin-1 and nectin-3, together with N-cadherin, are concentrated at puncta adherentia junctions (PAJs) in these synapses. Here, we investigated the roles of afadin in PAJ formation and presynaptic differentiation in mossy fiber-CA3 pyramidal cell synapses. At these synapses in the mice in which the afadin gene was conditionally inactivated before synaptogenesis by using nestin-Cre mice, the immunofluorescence signals for the PAJ components, nectin-1, nectin-3 and N-cadherin, disappeared almost completely, while those for the presynaptic components, VGLUT1 and bassoon, were markedly decreased. In addition, these signals were significantly decreased in cultured afadin-deficient hippocampal neurons. Furthermore, the interevent interval of miniature excitatory postsynaptic currents was prolonged in the cultured afadin-deficient hippocampal neurons compared with control neurons, indicating that presynaptic functions were suppressed or a number of synapse was reduced in the afadin-deficient neurons. Analyses of presynaptic vesicle recycling and paired recordings revealed that the cultured afadin-deficient neurons showed impaired presynaptic functions. These results indicate that afadin regulates both PAJ formation and presynaptic differentiation in most mossy fiber-CA3 pyramidal cell synapses, while in a considerable population of these neurons, afadin regulates only PAJ formation but not presynaptic differentiation. PMID:24587018

  13. Forebrain microglia from wild-type but not adult 5xFAD mice prevent amyloid-beta plaque formation in organotypic hippocampal slice cultures

    NARCIS (Netherlands)

    Hellwig, Sabine; Masuch, Annette; Nestel, Sigrun; Katzmarski, Natalie; Meyer-Luehmann, Melanie; Biber, Knut

    2015-01-01

    The role of microglia in amyloid-beta (A beta) deposition is controversial. In the present study, an organotypic hippocampal slice culture (OHSC) system with an in vivo-like microglial-neuronal environment was used to investigate the potential contribution of microglia to A beta plaque formation. We

  14. Glucose deprivation activates diversity of potassium channels in cultured rat hippocampal neurons.

    Science.gov (United States)

    Velasco, Myrian; García, Esperanza; Onetti, Carlos G

    2006-05-01

    1. Glucose is one of the most important substrates for generating metabolic energy required for the maintenance of cellular functions. Glucose-mediated changes in neuronal firing pattern have been observed in the central nervous system of mammals. K(+) channels directly regulated by intracellular ATP have been postulated as a linkage between cellular energetic metabolism and excitability; the functional roles ascribed to these channels include glucose-sensing to regulate energy homeostasis and neuroprotection under energy depletion conditions. The hippocampus is highly sensitive to metabolic insults and is the brain region most sensitive to ischemic damage. Because the identity of metabolically regulated potassium channels present in hippocampal neurons is obscure, we decided to study the biophysical properties of glucose-sensitive potassium channels in hippocampal neurons. 2. The dependence of membrane potential and the sensitivity of potassium channels to glucose and ATP in rat hippocampal neurons were studied in cell-attached and excised inside-out membrane patches. 3. We found that under hypoglycemic conditions, at least three types of potassium channels were activated; their unitary conductance values were 37, 147, and 241 pS in symmetrical K(+), and they were sensitive to ATP. For K(+) channels with unitary conductance of 37 and 241, when the membrane potential was depolarized the longer closed time constant diminished and this produced an increase in the open-state probability; nevertheless, the 147-pS channels were not voltage-dependent. 4. We propose that neuronal glucose-sensitive K(+) channels in rat hippocampus include subtypes of ATP-sensitive channels with a potential role in neuroprotection during short-term or prolonged metabolic stress.

  15. Block by a putative antiarrhythmic agent of a calcium-dependent potassium channel in cultured hippocampal neurons.

    Science.gov (United States)

    McLarnon, J G

    1990-05-04

    The actions of a new, putative antiarrhythmic drug, KC-8851 on single channel currents in hippocampal CA1 neurons have been studied. A calcium-dependent potassium current IK(Ca) was activated in the cultured neurons when a solution containing 140 mM K+ and 0.2 mM Ca2+ was applied to inside-out patches. Addition of the compound KC-8851, at concentrations between 1-50 microM, resulted in significant, dose-dependent, decreases in the mean open times of the K channel. The onward (blocking) rate constant was determined from a simple channel blockade scheme and was 5 x 10(7) M-1s-1; this rate constant was not dependent on voltage. Addition of KC-8851 to the solution bath with outside-out patches also caused significant decreases in the mean open times of the IK(Ca) channel consistent with channel blockade by the drug.

  16. The up-regulation of voltage-gated sodium channels subtypes coincides with an increased sodium current in hippocampal neuronal culture model.

    Science.gov (United States)

    Guo, Feng; Xu, Xiaoxue; Cai, Jiqun; Hu, Huiyuan; Sun, Wei; He, Guilin; Shao, Dongxue; Wang, Lei; Chen, Tianbao; Shaw, Chris; Zhu, Tong; Hao, Liying

    2013-02-01

    Voltage-gated sodium channels (VGSC) have been linked to inherited forms of epilepsy. The expression and biophysical properties of VGSC in the hippocampal neuronal culture model have not been clarified. In order to evaluate mechanisms of epileptogenesis that are related to VGSC, we examined the expression and function of VGSC in the hippocampal neuronal culture model in vitro and spontaneously epileptic rats (SER) in vivo. Our data showed that the peak amplitude of transient, rapidly-inactivating Na(+) current (I(Na,T)) in model neurons was significantly increased compared with control neurons, and the activation curve was shifted to the negative potentials in model neurons in whole cell recording by patch-clamp. In addition, channel activity of persistent, non-inactivating Na(+) current (I(Na,P)) was obviously increased in the hippocampal neuronal culture model as judged by single-channel patch-clamp recording. Furthermore, VGSC subtypes Na(V)1.1, Na(V)1.2 and Na(V)1.3 were up-regulated at the protein expression level in model neurons and SER as assessed by Western blotting. Four subtypes of VGSC proteins in SER were clearly present throughout the hippocampus, including CA1, CA3 and dentate gyrus regions, and neurons expressing VGSC immunoreactivity were also detected in hippocampal neuronal culture model by immunofluorescence. These findings suggested that the up-regulation of voltage-gated sodium channels subtypes in neurons coincided with an increased sodium current in the hippocampal neuronal culture model, providing a possible explanation for the observed seizure discharge and enhanced excitability in epilepsy.

  17. Brain-derived neurotrophic factor, but not neurotrophin-3, prevents ischaemia-induced neuronal cell death in organotypic rat hippocampal slice cultures.

    Science.gov (United States)

    Pringle, A K; Sundstrom, L E; Wilde, G J; Williams, L R; Iannotti, F

    1996-06-28

    We have investigated the neuroprotective actions of neurotrophins in a model of ischaemia using slice cultures. Ischaemia was induced in organotypic hippocampal cultures by simultaneous oxygen and glucose deprivation. Cell death was assessed 24 h later by propidium iodide fluorescence. Pre- but not post-ischaemic addition of brain-derived neurotrophic factor (BDNF) produced a concentration-dependent reduction in neuronal damage. Neurotrophin-3 was not neuroprotective. These data suggest that BDNF may form part of an endogenous neuroprotective mechanism.

  18. 3-Nitropropionic acid neurotoxicity in hippocampal slice cultures: developmental and regional vulnerability and dependency on glucose

    DEFF Research Database (Denmark)

    Noer, Helle; Kristensen, Bjarne W; Noraberg, Jens

    2002-01-01

    : CA1 > CA3 > fascia dentata. In low glucose much lower concentrations of 3-NP (25 microM) triggered neurotoxicity. One-week-old cultures were less susceptible to 3-NP toxicity than 3-week-old cultures, but the dentate granule cells were relatively more affected in the immature cultures. We found...

  19. Comparison of excitotoxic profiles of ATPA, AMPA, KA and NMDA in organotypic hippocampal slice cultures

    DEFF Research Database (Denmark)

    Kristensen, Bjarne Winther; Noraberg, J; Zimmer, J

    2001-01-01

    ) values was found after 2 days of exposure: AMPA (3.7 mM)>NMDA (11 mM)=KA (13 mM)>ATPA (33 mM). Exposed to 30 microM ATPA, 3 microM AMPA and 10 microM NMDA, CA1 was the most susceptible subfield followed by fascia dentata and CA3. Using 8 microM KA, CA3 was the most susceptible subfield, followed...... by fascia dentata and CA1. In 100 microM concentrations, all four agonists induced the same, maximal PI uptake in all hippocampal subfields, corresponding to total neuronal degeneration. Using glutamate receptor antagonists, like GYKI 52466, NBQX and MK-801, inhibition data revealed that AMPA excitotoxicity...

  20. Comparison of excitotoxic profiles of ATPA, AMPA, KA and NMDA in organotypic hippocampal slice cultures

    DEFF Research Database (Denmark)

    Kristensen, Bjarne Winther; Noraberg, J; Zimmer, J

    2001-01-01

    ) values was found after 2 days of exposure: AMPA (3.7 mM)>NMDA (11 mM)=KA (13 mM)>ATPA (33 mM). Exposed to 30 microM ATPA, 3 microM AMPA and 10 microM NMDA, CA1 was the most susceptible subfield followed by fascia dentata and CA3. Using 8 microM KA, CA3 was the most susceptible subfield, followed...... by fascia dentata and CA1. In 100 microM concentrations, all four agonists induced the same, maximal PI uptake in all hippocampal subfields, corresponding to total neuronal degeneration. Using glutamate receptor antagonists, like GYKI 52466, NBQX and MK-801, inhibition data revealed that AMPA excitotoxicity...

  1. Thermoluminescence of pyramid stones

    Energy Technology Data Exchange (ETDEWEB)

    Gomaa, M.A.; Eid, A.M. (Atomic Energy Establishment, Cairo (Egypt))

    1982-01-01

    It is the aim of the present study to investigate some thermoluminescence properties of pyramid stones. Using a few grammes of pyramid stones from Pyramids I and II, the TL glow peaks were observed at 250 and 310/sup 0/C, respectively. The TL glow peaks of samples annealed at 600/sup 0/C, then exposed to /sup 60/Co ..gamma..-rays were observed at 120, 190 and 310/sup 0/C, respectively. The accumulated dose of natural samples is estimated to be around 310 Gray (31 krad). By assuming an annual dose is 1 mGy, the estimated age of pyramid stones is 0.31 M year.

  2. Pyramid beam splitter

    Science.gov (United States)

    McKeown, Mark H.; Beason, Steven C.; Fairer, George

    1992-01-01

    The apparatus of the present invention provides means for obtaining accurate, dependable, measurement of bearings and directions for geologic mapping in subterranean shafts, such as, for example, nuclear waste storage investigations. In operation, a laser beam is projected along a reference bearing. A pyramid is mounted such that the laser beam is parallel to the pyramid axis and can impinge on the apex of the pyramid thus splitting the beam several ways into several beams at right angles to each other and at right angles to the reference beam. The pyramid is also translatable and rotatable in a plane perpendicular to the reference beam.

  3. Involvement of ClC-3 chloride/proton exchangers in controlling glutamatergic synaptic strength in cultured hippocampal neurons

    Directory of Open Access Journals (Sweden)

    Raul Enrique Guzman

    2014-05-01

    Full Text Available ClC-3 is a member of the CLC family of anion channels and transporters that localizes to early and late endosomes as well as to synaptic vesicles. Its genetic disruption in mouse models results in pronounced hippocampal and retinal neurodegeneration, suggesting that ClC-3 might be important for normal excitatory and/or inhibitory neurotransmission in central neurons. To characterize the role of ClC-3 in glutamate accumulation in synaptic vesicles we compared glutamatergic synaptic transmission in cultured hippocampal neurons from WT and Clcn3-/- mice. In Clcn3-/- neurons the amplitude and frequency of miniature as well as the amplitudes of action-potential evoked EPSCs were significantly increased as compared to WT neurons. The low-affinity competitive AMPA receptor antagonist -DGG reduced the quantal size of synaptic events more effectively in WT than in Clcn3-/- neurons, whereas no difference was observed for the high-affinity competitive non-NMDA antagonist NBQX. Paired pulse ratios of evoked EPSCs were significantly reduced, whereas the size of the readily releasable pool was not affected by the genetic ablation of ClC-3. Electron microscopy revealed increased volumes of synaptic vesicles in hippocampi of Clcn3-/- mice. Our findings demonstrate that ClC-3 controls fast excitatory synaptic transmission by regulating the amount of neurotransmitter as well as the release probability of synaptic vesicles. These results provide novel insights into the role of ClC-3 in synaptic transmission and identify excessive glutamate release as a likely basis of neurodegeneration in Clcn3-/-.

  4. Oxygen glucose deprivation in rat hippocampal slice cultures results in alterations in carnitine homeostasis and mitochondrial dysfunction.

    Directory of Open Access Journals (Sweden)

    Thomas F Rau

    Full Text Available Mitochondrial dysfunction characterized by depolarization of mitochondrial membranes and the initiation of mitochondrial-mediated apoptosis are pathological responses to hypoxia-ischemia (HI in the neonatal brain. Carnitine metabolism directly supports mitochondrial metabolism by shuttling long chain fatty acids across the inner mitochondrial membrane for beta-oxidation. Our previous studies have shown that HI disrupts carnitine homeostasis in neonatal rats and that L-carnitine can be neuroprotective. Thus, this study was undertaken to elucidate the molecular mechanisms by which HI alters carnitine metabolism and to begin to elucidate the mechanism underlying the neuroprotective effect of L-carnitine (LCAR supplementation. Utilizing neonatal rat hippocampal slice cultures we found that oxygen glucose deprivation (OGD decreased the levels of free carnitines (FC and increased the acylcarnitine (AC: FC ratio. These changes in carnitine homeostasis correlated with decreases in the protein levels of carnitine palmitoyl transferase (CPT 1 and 2. LCAR supplementation prevented the decrease in CPT1 and CPT2, enhanced both FC and the AC∶FC ratio and increased slice culture metabolic viability, the mitochondrial membrane potential prior to OGD and prevented the subsequent loss of neurons during later stages of reperfusion through a reduction in apoptotic cell death. Finally, we found that LCAR supplementation preserved the structural integrity and synaptic transmission within the hippocampus after OGD. Thus, we conclude that LCAR supplementation preserves the key enzymes responsible for maintaining carnitine homeostasis and preserves both cell viability and synaptic transmission after OGD.

  5. Application of the Co-culture Membrane System Pointed to a Protective Role of Catestatin on Hippocampal Plus Hypothalamic Neurons Exposed to Oxygen and Glucose Deprivation.

    Science.gov (United States)

    Mele, Maria; Morelli, Sabrina; Fazzari, Gilda; Avolio, Ennio; Alò, Raffaella; Piscioneri, Antonella; De Bartolo, Loredana; Facciolo, Rosa Maria; Canonaco, Marcello

    2016-11-05

    Depletion of oxygen and glucose even for brief periods is sufficient to cause cerebral ischemia, which is a predominant worldwide cause of motor deficits with the reduction of life quality and subsequently death. Hence, more insights regarding protective measures against ischemic events are becoming a major research goal. Among the many neuronal factors, N-methyl-D-aspartate receptors (NMDAR), orexinergic neuroreceptors (ORXR), and sympatho-inhibitory neuropeptide catestatin (CST) are widely involved with ischemic episodes. In this study, it was possible to induce in vitro ischemic conditions of the hamster (Mesocricetus auratus) hippocampal and hypothalamic neuronal cultures, grown on a newly compartmentalized membrane system, via oxygen and glucose deprivation (OGD). These cultures displayed notably differentiated NMDARergic and ORXergic receptor expression activities along with evident brain-derived neurotrophic factor (BDNF) plus orexin A (ORX-A) secretion, especially under co-cultured conditions. Interestingly, addition of CST in OGD-insulted hippocampal cells accounted for upregulated GluN1 and ORX1R transcripts that in the case of the latter neuroreceptor was very strongly (p BDNF and ORX-A secretion in the presence of hippocampal cells. Overall, the preferential CST effects on BDNF plus ORX-A production together with altered NMDAR and ORXR levels, especially in co-cultured hypothalamic cells pointed to ORX-containing neurons as major protective constituents against ischemic damages thus opening new scenarios on the cross-talking roles of CST during ischemic disorders.

  6. Rebuilding the Food Pyramid.

    Science.gov (United States)

    Willet, Walter C.; Stampfer, Meir J.

    2003-01-01

    Discusses the old food guide pyramid released in 1992 by the U.S. Department of Agriculture. Contradicts the message that fat is bad, which was presented to the public by nutritionists, and the effects of plant oils on cholesterol. Introduces a new food pyramid. (YDS)

  7. The Healthy Eating Pyramid

    Institute of Scientific and Technical Information of China (English)

    Jimmy; Lin

    2007-01-01

    Experts from the Harvard School of Public Health created the Healthy Eating Pyramid.The pyramid is about the links between diet and health and offers useable information to help people make better choices about what to eat. Remember:its base is daily exercise and weight control.

  8. Sparse and Specific Coding during Information Transmission between Co-cultured Dentate Gyrus and CA3 Hippocampal Networks.

    Science.gov (United States)

    Poli, Daniele; Thiagarajan, Srikanth; DeMarse, Thomas B; Wheeler, Bruce C; Brewer, Gregory J

    2017-01-01

    To better understand encoding and decoding of stimulus information in two specific hippocampal sub-regions, we isolated and co-cultured rat primary dentate gyrus (DG) and CA3 neurons within a two-chamber device with axonal connectivity via micro-tunnels. We tested the hypothesis that, in these engineered networks, decoding performance of stimulus site information would be more accurate when stimuli and information flow occur in anatomically correct feed-forward DG to CA3 vs. CA3 back to DG. In particular, we characterized the neural code of these sub-regions by measuring sparseness and uniqueness of the responses evoked by specific paired-pulse stimuli. We used the evoked responses in CA3 to decode the stimulation sites in DG (and vice-versa) by means of learning algorithms for classification (support vector machine, SVM). The device was placed over an 8 × 8 grid of extracellular electrodes (micro-electrode array, MEA) in order to provide a platform for monitoring development, self-organization, and improved access to stimulation and recording at multiple sites. The micro-tunnels were designed with dimensions 3 × 10 × 400 μm allowing axonal growth but not migration of cell bodies and long enough to exclude traversal by dendrites. Paired-pulse stimulation (inter-pulse interval 50 ms) was applied at 22 different sites and repeated 25 times in each chamber for each sub-region to evoke time-locked activity. DG-DG and CA3-CA3 networks were used as controls. Stimulation in DG drove signals through the axons in the tunnels to activate a relatively small set of specific electrodes in CA3 (sparse code). CA3-CA3 and DG-DG controls were less sparse in coding than CA3 in DG-CA3 networks. Using all target electrodes with the three highest spike rates (14%), the evoked responses in CA3 specified each stimulation site in DG with optimum uniqueness of 64%. Finally, by SVM learning, these evoked responses in CA3 correctly decoded the stimulation sites in DG for 43% of the

  9. Sparse and Specific Coding during Information Transmission between Co-cultured Dentate Gyrus and CA3 Hippocampal Networks

    Science.gov (United States)

    Poli, Daniele; Thiagarajan, Srikanth; DeMarse, Thomas B.; Wheeler, Bruce C.; Brewer, Gregory J.

    2017-01-01

    To better understand encoding and decoding of stimulus information in two specific hippocampal sub-regions, we isolated and co-cultured rat primary dentate gyrus (DG) and CA3 neurons within a two-chamber device with axonal connectivity via micro-tunnels. We tested the hypothesis that, in these engineered networks, decoding performance of stimulus site information would be more accurate when stimuli and information flow occur in anatomically correct feed-forward DG to CA3 vs. CA3 back to DG. In particular, we characterized the neural code of these sub-regions by measuring sparseness and uniqueness of the responses evoked by specific paired-pulse stimuli. We used the evoked responses in CA3 to decode the stimulation sites in DG (and vice-versa) by means of learning algorithms for classification (support vector machine, SVM). The device was placed over an 8 × 8 grid of extracellular electrodes (micro-electrode array, MEA) in order to provide a platform for monitoring development, self-organization, and improved access to stimulation and recording at multiple sites. The micro-tunnels were designed with dimensions 3 × 10 × 400 μm allowing axonal growth but not migration of cell bodies and long enough to exclude traversal by dendrites. Paired-pulse stimulation (inter-pulse interval 50 ms) was applied at 22 different sites and repeated 25 times in each chamber for each sub-region to evoke time-locked activity. DG-DG and CA3-CA3 networks were used as controls. Stimulation in DG drove signals through the axons in the tunnels to activate a relatively small set of specific electrodes in CA3 (sparse code). CA3-CA3 and DG-DG controls were less sparse in coding than CA3 in DG-CA3 networks. Using all target electrodes with the three highest spike rates (14%), the evoked responses in CA3 specified each stimulation site in DG with optimum uniqueness of 64%. Finally, by SVM learning, these evoked responses in CA3 correctly decoded the stimulation sites in DG for 43% of the

  10. Oxygen-glucose deprivation promotes gliogenesis and microglia activation in organotypic hippocampal slice culture: involvement of metalloproteinases.

    Science.gov (United States)

    Ziemka-Nałęcz, Małgorzata; Stanaszek, Luiza; Zalewska, Teresa

    2013-01-01

    Organotypic hippocampal cultures are used as an alternative model for studying molecular mechanism(s) of neurogenesis after combined oxygen-glucose deprivation (OGD) mimicking ischemic conditions. The aim of the present work was to investigate the effect of OGD on stem/progenitor cells proliferation and/or differentiation in the hippocampus. Our attention was primarily focused on the relationship between neurogenesis-associated processes and activity of matrix metalloproteinases (MMPs). Cell proliferation was detected by using BrdU incorporation. Newly generated BrdU (+) cells were identified by labeling with specific cell markers. In order to check the activity and localization of MMPs we conducted in situ zymography in conjunction with immunohistochemistry. In our experimental conditions OGD-insult followed by 24 h of recovery caused the damage of neuronal cells in CA1. At 1 week cell death appears all over the hippocampus. We found that expected stimulation of endogenous neurogenesis fails as a source of compensation for the lost neurons in OGD-treated cultures. The modulation of culture microenvironment after ischemia favors the dominant proliferation of glial cells expressed by the enhancement of newly-generated oligodendrocyte progenitors. In addition, during our study we also detected some BrdU labeled nuclei encapsulated by GFAP positive processes. However, the majority of BrdU positive cells expressed microglial specific stain, particularly pronounced in CA1area. The OGD-promoted responses involved activation of metalloproteinases, which matches the progression of gliogenesis. On the other hand, the high activity of MMPs associated with microglial cells implicate their involvement in the mechanism participating in OGD-induced cell damage.

  11. Differential induction of heme oxygenase and other stress proteins in cultured hippocampal astrocytes and neurons by inorganic lead.

    Science.gov (United States)

    Cabell, Leigh; Ferguson, Charles; Luginbill, Deana; Kern, Marcey; Weingart, Adam; Audesirk, Gerald

    2004-07-01

    We examined the effects of exposure to inorganic lead (Pb2+) on the induction of stress proteins in cultured hippocampal neurons and astrocytes, with particular emphasis on the induction of heme oxygenase-1 (HO-1). In radiolabeled neuronal cultures, Pb2+ exposure had no significant effect on the synthesis of any protein at any concentration (up to 250 microM) or duration of exposure (up to 4 days). In radiolabeled astrocyte cultures, however, Pb2+ exposure (100 nM to 100 microM; 1-4 days) increased synthesis of proteins with approximate molecular weights of 23, 32, 45, 57, 72, and 90 kDa. Immunoblot experiments showed that Pb2+ exposure (100 nM to 10 microM, 1-14 days) induces HO-1 synthesis in astrocytes, but not in neurons; this is probably the 32-kDa protein. The other heme oxygenase isoform, HO-2, is present in both neurons and astrocytes, but is not inducible by Pb2+ at concentrations up to 100 microM. HO-1 can be induced by a variety of stimuli. We found that HO-1 induction in astrocytes is increased by combined exposure to Pb2+ and many other stresses, including heat, nitric oxide, H2O2, and superoxide. One of the stimuli that may induce HO-1 is oxidative stress. Lead exposure causes oxidative stress in many cell types, including astrocytes. Induction of HO-1 by Pb2+ is reduced by the hydroxyl radical scavengers dimethylthiourea (DMTU) and mannitol, but not by inhibitors of calmodulin, calmodulin-dependent protein kinases, protein kinase C, or extracellular signal-regulated kinases (ERK). Therefore, we conclude that oxidative stress is an important mechanism by which Pb2+ induces HO-1 synthesis in astrocytes.

  12. Biocompatibility of silicon-based arrays of electrodes coupled to organotypic hippocampal brain slice cultures

    DEFF Research Database (Denmark)

    Kristensen, Bjarne Winther; Noraberg, J; Thiébaud, P

    2001-01-01

    ) rats were grown for 4-8 weeks on the perforated silicon chips with silicon nitride surfaces and 40 microm sized holes and compared with corresponding tissue slices grown on conventional semiporous membranes. In terms of preservation of the basic cellular and connective organization, as visualized...... around the upper recording part of the 47-microm-high platinum-tip electrodes. Slice cultures grown on a separate set of chips with platinum instead of silicon nitride surfaces also displayed normal MAP2 and GFAP immunostaining. The width of the GFAP-rich zone (glia limitans) at the bottom surface...... of the slice cultures was the same ( approximately 20 microm) in cultures grown on chips with silicon nitride and platinum surfaces and on conventional insert membranes. The slice cultures grown on chips maintained a normal, subfield differentiated susceptibility to the glutamate receptor agonist N...

  13. AHP 21: Pyramid Schemes on the Tibetan Plateau

    Directory of Open Access Journals (Sweden)

    Devin Gonier

    2017-09-01

    Full Text Available The unique features of pyramid shemes and certain underlying causes for their development on the Tibetan Plateau are analyzed. Research was conducted by analyzing 521 surveys, allowing estimation of pyramid scheme activity on the Plateau and an identification of related cultural and social specificities. Firsthand accounts were collected revealing details of personal involvement. Survey data and similarities in the accounts were studied to suggest how involvement in pyramid schemes might be reduced at both institutional and individual levels.

  14. Reduction of beta-amyloid-induced neurotoxicity on hippocampal cell cultures by moderate acidosis is mediated by transforming growth factor beta.

    Science.gov (United States)

    Uribe-San Martín, R; Herrera-Molina, R; Olavarría, L; Ramírez, G; von Bernhardi, R

    2009-02-18

    Progression of Alzheimer's disease (AD) is associated with chronic inflammation and microvascular alterations, which can induce impairment of brain perfusion because of vascular pathology and local acidosis. Acidosis can promote amyloidogenesis, which could further contribute to neurodegenerative changes. Nevertheless, there is also evidence that acidosis has neuroprotective effects in hypoxia models. Here we studied the effect of moderate acidosis on beta-amyloid (Abeta)-mediated neurotoxicity. We evaluated morphological changes, cell death, nitrite production and reductive metabolism of hippocampal cultures from Sprague-Dawley rats exposed to Abeta under physiological (pH 7.4) or moderate acidosis (pH 7.15-7.05). In addition, because transforming growth factor beta (TGFbeta) 1 is neuroprotective and is induced by several pathophysiological conditions, we assessed its presence at the different pHs. The exposure of hippocampal cells to Abeta induced a conspicuous reduction of neurites' arborization, as well as increased neuronal death and nitric oxide production. However, Abeta neurotoxicity was significantly attenuated when hippocampal cultures were kept at pH 7.15-7.05, showing a 68% reduction on lactate dehydrogenase release compared with cultures exposed to Abeta at pH 7.4 (Pacidosis compared with basal pH media (Pacidosis decreased intracellular TGFbeta1 precursor (latency associated protein-TGFbeta1) and increased up to fourfold TGFbeta1 bioactivity, detecting a 43% increase in the active TGFbeta levels in cultures exposed to Abeta and moderate acidosis. Inhibition of TGFbeta signaling abolished the neuroprotective effect of moderate acidosis. Our results show that moderate acidosis protected hippocampal cells from Abeta-mediated neurotoxicity through the increased activation and signaling potentiation of TGFbeta.

  15. PCB 136 atropselectively alters morphometric and functional parameters of neuronal connectivity in cultured rat hippocampal neurons via ryanodine receptor-dependent mechanisms.

    Science.gov (United States)

    Yang, Dongren; Kania-Korwel, Izabela; Ghogha, Atefeh; Chen, Hao; Stamou, Marianna; Bose, Diptiman D; Pessah, Isaac N; Lehmler, Hans-Joachim; Lein, Pamela J

    2014-04-01

    We recently demonstrated that polychlorinated biphenyl (PCB) congeners with multiple ortho chlorine substitutions sensitize ryanodine receptors (RyRs), and this activity promotes Ca²⁺-dependent dendritic growth in cultured neurons. Many ortho-substituted congeners display axial chirality, and we previously reported that the chiral congener PCB 136 (2,2',3,3',6,6'-hexachlorobiphenyl) atropselectively sensitizes RyRs. Here, we test the hypothesis that PCB 136 atropisomers differentially alter dendritic growth and other parameters of neuronal connectivity influenced by RyR activity. (-)-PCB 136, which potently sensitizes RyRs, enhances dendritic growth in primary cultures of rat hippocampal neurons, whereas (+)-PCB 136, which lacks RyR activity, has no effect on dendritic growth. The dendrite-promoting activity of (-)-PCB 136 is observed at concentrations ranging from 0.1 to 100 nM and is blocked by pharmacologic RyR antagonism. Neither atropisomer alters axonal growth or cell viability. Quantification of PCB 136 atropisomers in hippocampal cultures indicates that atropselective effects on dendritic growth are not due to differential partitioning of atropisomers into cultured cells. Imaging of hippocampal neurons loaded with Ca²⁺-sensitive dye demonstrates that (-)-PCB 136 but not (+)-PCB 136 increases the frequency of spontaneous Ca²⁺ oscillations. Similarly, (-)-PCB 136 but not (+)-PCB 136 increases the activity of hippocampal neurons plated on microelectrode arrays. These data support the hypothesis that atropselective effects on RyR activity translate into atropselective effects of PCB 136 atropisomers on neuronal connectivity, and suggest that the variable atropisomeric enrichment of chiral PCBs observed in the human population may be a significant determinant of individual susceptibility for adverse neurodevelopmental outcomes following PCB exposure.

  16. 慢性脑缺血大鼠海马CA1区锥体细胞树突形态及树突棘密度的变化%Changes of dendritic morphology and spine density in hippocampal CA1 pyramidal cells of chronic cerebral ischemic rats

    Institute of Scientific and Technical Information of China (English)

    贾贺; 张博爱; 刘宇; 张小敏; 姬亚杰; 李星; 刘荣丽

    2012-01-01

    目的:研究慢性脑缺血大鼠海马CA1区锥体细胞树突形态及树突棘密度的变化.方法:对大鼠进行双侧颈总动脉永久性结扎(2VO)制备慢性脑缺血模型,分别于2周、4周、8周通过Morris水迷宫对各组大鼠进行行为学评价,筛选造模成功大鼠,进行Golgi染色,光镜下观察海马CA1区锥体细胞树突的分支、长度及树突棘密度的变化.结果:与对照组相比,4周、8周模型组树突的分支及长度显著减少(P<0.01),各周模型组树突棘的密度均有显著减少(P<0.01);模型组内随着缺血时间延长,树突的分支及长度、树突棘密度均显著减少(P<0.05).结论:慢性脑缺血可导致海马CA1区锥体细胞树突及树突棘损伤性变化,从而构成进展性认知功能障碍的病理生理学基础.%AIM:To investigate the changes of dendritic morphology and spine density in hippocampal CA1 pyramidal cells of the chronic cerebral ischemic rats. METHODS:The model of chronic cerebral ischemia was established by permanent occlusion of the bilateral common carotid arteries ( 2VO ) in rats. Two weeks, 4 weeks or 8 weeks later, the behavior of the rats in each group was evaluated through the Morris water maze to select the successful modeling, and the brains were collected for processing Golgi staining. The changes in dendritic branch and length, and spine density in hippocampal CA1 pyramidal cells were observed under optical microscope. RESULTS: Compared with sham - operated group, dendritic branch and length in model group was significantly reduced in 4 -week group and 8 -week group ( P <0. 01 ), and spine density in model group were significantly reduced in 2 -week, 4 -week and 8 -week groups ( P <0. 01 ). With prolonged ischemia, dendritic branch and length, and spine density in model group were all significantly reduced ( P < 0. 05 ). CONCLUSION: Chronic cerebral ischemia leads to traumatic changes in dendrites and spines in hippocampal CA1 pyramidal cells, which

  17. Nanomolar concentrations of nicotine and cotinine alter the development of cultured hippocampal neurons via non-acetylcholine receptor-mediated mechanisms.

    Science.gov (United States)

    Audesirk, T; Cabell, L

    1999-08-01

    We investigated the effects of nicotine and its metabolic byproduct cotinine on survival, differentiation and intracellular Ca2+ levels of cultured E18 rat hippocampal neurons. We used a range of concentrations from 1 nM to 10 microM, most of which are within the likely range of human fetal exposure from maternal smoking. Nicotine did not influence neuron survival or neurite production. However, at all concentrations tested, nicotine significantly increased branching of both axons and dendrites, an effect which was not reversed by co-culturing with alpha-bungarotoxin, which blocks the nicotinic acetylcholine receptors that predominate in hippocampal cultures (Alkondon and Albuquerque, 1993; Barrantes et al., 1995b). Cotinine at 100 nM and 1 microM significantly reduced neuron survival and neurite production of surviving neurons, but did not significantly alter axon or dendrite branching. These membrane-permeable compounds may work synergistically in the developing embryo to impair the survival and differentiation of hippocampal neurons via intracellular mechanisms.

  18. Neuroprotective Effects of α-Tocotrienol on Kainic Acid-Induced Neurotoxicity in Organotypic Hippocampal Slice Cultures

    Directory of Open Access Journals (Sweden)

    Bae Hwan Lee

    2013-09-01

    Full Text Available Vitamin E, such as alpha-tocopherol (ATPH and alpha-tocotrienol (ATTN, is a chain-breaking antioxidant that prevents the chain propagation step during lipid peroxidation. In the present study, we investigated the effects of ATTN on KA-induced neuronal death using organotypic hippocampal slice culture (OHSC and compared the neuroprotective effects of ATTN and ATPH. After 15 h KA (5 µM treatment, delayed neuronal death was detected in the CA3 region and reactive oxygen species (ROS formation and lipid peroxidation were also increased. Both co-treatment and post-treatment of ATPH (100 µM or ATTN (100 µM significantly increased the cell survival and reduced the number of TUNEL-positive cells in the CA3 region. Increased dichlorofluorescein (DCF fluorescence and levels of thiobarbiturate reactive substances (TBARS were decreased by ATPH and ATTN treatment. These data suggest that ATPH and ATTN treatment have protective effects on KA-induced cell death in OHSC. ATTN treatment tended to be more effective than ATPH treatment, even though there was no significant difference between ATPH and ATTN in co-treatment or post-treatment.

  19. Protective Effects of Testosterone on Presynaptic Terminals against Oligomeric β-Amyloid Peptide in Primary Culture of Hippocampal Neurons

    Directory of Open Access Journals (Sweden)

    Chi-Fai Lau

    2014-01-01

    Full Text Available Increasing lines of evidence support that testosterone may have neuroprotective effects. While observational studies reported an association between higher bioavailable testosterone or brain testosterone levels and reduced risk of Alzheimer’s disease (AD, there is limited understanding of the underlying neuroprotective mechanisms. Previous studies demonstrated that testosterone could alleviate neurotoxicity induced by β-amyloid (Aβ, but these findings mainly focused on neuronal apoptosis. Since synaptic dysfunction and degeneration are early events during the pathogenesis of AD, we aim to investigate the effects of testosterone on oligomeric Aβ-induced synaptic changes. Our data suggested that exposure of primary cultured hippocampal neurons to oligomeric Aβ could reduce the length of neurites and decrease the expression of presynaptic proteins including synaptophysin, synaptotagmin, and synapsin-1. Aβ also disrupted synaptic vesicle recycling and protein folding machinery. Testosterone preserved the integrity of neurites and the expression of presynaptic proteins. It also attenuated Aβ-induced impairment of synaptic exocytosis. By using letrozole as an aromatase antagonist, we further demonstrated that the effects of testosterone on exocytosis were unlikely to be mediated through the estrogen receptor pathway. Furthermore, we showed that testosterone could attenuate Aβ-induced reduction of HSP70, which suggests a novel mechanism that links testosterone and its protective function on Aβ-induced synaptic damage. Taken together, our data provide further evidence on the beneficial effects of testosterone, which may be useful for future drug development for AD.

  20. Reaction of small heat-shock proteins to different kinds of cellular stress in cultured rat hippocampal neurons.

    Science.gov (United States)

    Bartelt-Kirbach, Britta; Golenhofen, Nikola

    2014-01-01

    Upregulation of small heat-shock proteins (sHsps) in response to cellular stress is one mechanism to increase cell viability.We previously described that cultured rat hippocampal neurons express five of the 11 family members but only upregulate two of them (HspB1 and HspB5) at the protein level after heat stress. Since neurons have to cope with many other pathological conditions, we investigated in this study the expression of all five expressed sHsps on mRNA and protein level after sublethal sodium arsenite and oxidative and hyperosmotic stress. Under all three conditions, HspB1, HspB5, HspB6, and HspB8 but not HspB11 were consistently upregulated but showed differences in the time course of upregulation. The increase of sHsps always occurred earlier on mRNA level compared with protein levels. We conclude from our data that these four upregulated sHsps (HspB1, HspB5, HspB6, HspB8) act together in different proportions in the protection of neurons from various stress conditions.

  1. Effects of cordycepin on the microglia-overactivation-induced impairments of growth and development of hippocampal cultured neurons.

    Directory of Open Access Journals (Sweden)

    Jie Peng

    Full Text Available Microglial cells are normally activated in response to brain injury or immunological stimuli to protect central nervous system (CNS. However, over-activation of microglia conversely amplifies the inflammatory effects and mediates cellular degeneration, leading to the death of neurons. Recently, cordycepin, an active component found in Cordyceps militarisa known as a rare Chinese caterpillar fungus, has been reported as an effective drug for treating inflammatory diseases and cancer via unclear mechanisms. In this study, we attempted to identify the anti-inflammatory role of cordycepin and its protective effects on the impairments of neural growth and development induced by microglial over-activation. The results indicate that cordycepin could attenuate the lipopolysaccharide (LPS-induced microglial activation, evidenced by the dramatically reduced release of TNF-α and IL-1β, as well as the down-regulation of mRNA levels of iNOS and COX-2 after cordycepin treatment. Besides, cordycepin reversed the LPS-induced activation of NF-κB pathway, resulting in anti-inflammatory effects. Furthermore, by employing the conditioned medium (CM, we found cordycepin was able to recover the impairments of neural growth and development in the primary hippocampal neurons cultured in LPS-CM, including cell viability, growth cone extension, neurite sprouting and outgrowth as well as spinogenesis. This study expands our knowledge of the anti-inflammatory function of cordycepin and paves the way for the biomedical applications of cordycepin in the therapies of neural injuries.

  2. Electrophysiology of embryonic, adult and aged rat hippocampal neurons in serum-free culture.

    Science.gov (United States)

    Evans, M S; Collings, M A; Brewer, G J

    1998-01-31

    Methods were recently developed for culturing neurons from adult rat hippocampus using the serum-free medium Neurobasal with B27 supplement. To determine whether adult cultured neurons have normal electrical properties, we studied cultures from rats of three age groups: (1) embryonic; (2) 10-11 months old and (3) 35-36 months old. Neurons had a polarized morphology with a large branching apical dendrite and small basal dendrites. Mean resting potentials were similar in the three age groups. All neurons had nonlinear current-voltage relationships, indicating the presence of voltage-sensitive ion channels. Most neurons had a voltage-sensitive inward current followed by a sustained voltage-sensitive outward current. Tetrodotoxin blocked the inward current, which is likely to be a sodium current. The sustained outward current, which is likely to be a potassium current, reversed at -71 mV. Most neurons exhibited anomalous rectification. Calcium currents were present in both embryonic and adult neurons. Embryonic neurons would sometimes fire multiple action potentials but adult neurons fired only single action potentials. Our results indicate that both embryonic and adult cultured neurons retain a clearly neuronal electrophysiological phenotype in Neurobasal/B27 serum-free medium.

  3. Hippocampal neurons in organotypic slice culture are highly resistant to damage by endogenous and exogenous nitric oxide.

    Science.gov (United States)

    Keynes, Robert G; Duport, Sophie; Garthwaite, John

    2004-03-01

    Nitric oxide (NO) has been proposed to mediate neurodegeneration arising from NMDA receptor activity, but the issue remains controversial. The hypothesis was re-examined using organotypic slice cultures of rat hippocampus, with steps being taken to avoid known artefacts. The NO-cGMP signalling pathway was well preserved in such cultures. Brief exposure to NMDA resulted in a concentration-dependent delayed neuronal death that could be nullified by administration of the NMDA antagonist MK801 (10 microm) given postexposure. Two inhibitors of NO synthesis failed to protect the slices, despite fully blocking NMDA-induced cGMP accumulation. By comparing NMDA-induced cGMP accumulation with that produced by an NO donor, toxic NMDA concentrations were estimated to produce only physiological NO concentrations (2 nm). In studies of the vulnerability of the slices to exogenous NO, it was found that continuous exposure to up to 4.5 microm NO failed to affect ATP levels (measured after 6 h) or cause damage during 24 h, whereas treatment with the respiratory inhibitors myxothiazol or cyanide caused ATP depletion and complete cell death within 24 h. An NO concentration of 10 microm was required for ATP depletion and cell death, presumably through respiratory inhibition. It is concluded that sustained activity of neuronal NO synthase in intact hippocampal tissue can generate only low nanomolar NO concentrations, which are unlikely to be toxic. At the same time, the tissue is remarkably resistant to exogenous NO at up to 1000-fold higher concentrations. Together, the results seriously question the proposed role of NO in NMDA receptor-mediated excitotoxicity.

  4. Hippocampal Dendritic Spines Are Segregated Depending on Their Actin Polymerization

    Directory of Open Access Journals (Sweden)

    Nuria Domínguez-Iturza

    2016-01-01

    Full Text Available Dendritic spines are mushroom-shaped protrusions of the postsynaptic membrane. Spines receive the majority of glutamatergic synaptic inputs. Their morphology, dynamics, and density have been related to synaptic plasticity and learning. The main determinant of spine shape is filamentous actin. Using FRAP, we have reexamined the actin dynamics of individual spines from pyramidal hippocampal neurons, both in cultures and in hippocampal organotypic slices. Our results indicate that, in cultures, the actin mobile fraction is independently regulated at the individual spine level, and mobile fraction values do not correlate with either age or distance from the soma. The most significant factor regulating actin mobile fraction was the presence of astrocytes in the culture substrate. Spines from neurons growing in the virtual absence of astrocytes have a more stable actin cytoskeleton, while spines from neurons growing in close contact with astrocytes show a more dynamic cytoskeleton. According to their recovery time, spines were distributed into two populations with slower and faster recovery times, while spines from slice cultures were grouped into one population. Finally, employing fast lineal acquisition protocols, we confirmed the existence of loci with high polymerization rates within the spine.

  5. Management Education and the Base of the Pyramid

    Science.gov (United States)

    Gordon, Michael D.

    2008-01-01

    Doing business at the base of the pyramid is a topic of increasing interest to business practitioners and academics. Base of the pyramid business offers the promise of great economic gains for companies and the possibility of a powerful new approach to alleviate poverty. At the same time, it may threaten local culture and independence while…

  6. Effects of selective inhibition of protein kinase C, cyclic AMP-dependent protein kinase, and Ca(2+)-calmodulin-dependent protein kinase on neurite development in cultured rat hippocampal neurons.

    Science.gov (United States)

    Cabell, L; Audesirk, G

    1993-06-01

    A variety of experimental evidence suggests that calmodulin and protein kinases, especially protein kinase C, may participate in regulating neurite development in cultured neurons, particularly neurite initiation. However, the results are somewhat contradictory. Further, the roles of calmodulin and protein kinases on many aspects of neurite development, such as branching or elongation of axons vs dendrites, have not been extensively studied. Cultured embryonic rat hippocampal pyramidal neurons develop readily identifiable axons and dendrites. We used this culture system and the new generation of highly specific protein kinase inhibitors to investigate the roles of protein kinases and calmodulin in neurite development. Neurons were cultured for 2 days in the continuous presence of calphostin C (a specific inhibitor of protein kinase C), KT5720 (inhibitor of cyclic AMP-dependent protein kinase), KN62 (inhibitor of Ca(2+)-calmodulin-dependent protein kinase II), or calmidazolium (inhibitor of calmodulin), each at concentrations from approximately 1 to 10 times the concentration reported in the literature to inhibit each kinase by 50%. The effects of phorbol 12-myristate 13-acetate (an activator of protein kinase C) and 4 alpha-phorbol 12,13-didecanoate (an inactive phorbol ester) were also tested. At concentrations that had no effect on neuronal viability, calphostin C reduced neurite initiation and axon branching without significantly affecting the number of dendrites per neuron, dendrite branching, dendrite length, or axon length. Phorbol 12-myristate 13-acetate increased axon branching and the number of dendrites per cell, compared to the inactive 4 alpha-phorbol 12,13-didecanoate. KT5720 inhibited only axon branching. KN62 reduced axon length, the number of dendrites per neuron, and both axon and dendrite branching. At low concentrations, calmidazolium had no effect on any aspect of neurite development, but at high concentrations, calmidazolium inhibited every

  7. Cultured hippocampal neurons from trisomy 16 mouse, a model for Down's syndrome, have an abnormal action potential due to a reduced inward sodium current.

    Science.gov (United States)

    Galdzicki, Z; Coan, E; Rapoport, S I

    1993-02-26

    Mouse trisomy 16 is an animal model for Down's syndrome (human trisomy 21). The whole-cell patch-clamp technique was used to compare passive and active electrical properties of trisomy 16 and diploid mouse 16 fetal hippocampal neurons maintained in culture for 2-5 weeks. There was no significant difference in any mean passive property, including resting potential, membrane resistance, capacitance and time constant. However, in trisomic neurons, the action potential had a 20% significantly slower rising phase and a 20% significantly smaller inward sodium current and inward sodium conductance than did control neurons. The outward conductance was not altered. The ratio of maximum inward conductance to maximum outward conductance was 30% less in the trisomy 16 cells. These results indicate that trisomy 16 hippocampal neurons have abnormal active electrical properties, most likely reflecting reduced sodium channel membrane density. Such subtle differences may influence elaboration of the hippocampus during development.

  8. Ginsenoside Rb1 selectively inhibits the activity of L-type voltage-gated calcium channels in cultured rat hippocampal neurons

    Institute of Scientific and Technical Information of China (English)

    Zhi-ying LIN; Li-min CHEN; Jing ZHANG; Xiao-dong PAN; Yuan-gui ZHU; Qin-yong YE; Hua-pin HUANG; Xiao-chun CHEN

    2012-01-01

    Aim:To investigate the effect of ginsenoside Rb1 on voltage-gated calcium currents in cultured rat hippocampal neurons and the modulatory mechanism.Methods:Cultured hippocampal neurons were prepared from Sprague Dawley rat embryos.Whole-cell configuration of the patchclamp technique was used to record the voltage-gated calcium currents (VGCCs)from the hippocampal neurons,and the effect of Rb1 was examined.Results:Rb1 (2-100 μmol/L)inhibited VGCCs in a concentration-dependent manner,and the current was mostly recovered upon wash-out.The specific L-type Ca2+ channel inhibitor nifedipine (10 μmol/L)occluded Rb1-induced inhibition on VGCCs.Neither the selective N-type Ca2+ channel blocker ω-conotoxin-GVlA (1 μmoVL),nor the selective P/Q-type Ca2+ channel blocker ωo-agatoxin IVA (30 nmol/L)diminished Rb1-sensitive VGCCs.Rb1 induced a leftward shift of the steady-state inactivation curve of Ica to a negative potential without affecting its activation kinetics or reversal potential in the I-V curve.The inhibitory effect of Rb1 was neither abolished by the adenylyl cyclase activator forskolin (10 μmol/L),nor by the PKA inhibitor H-89 (10 μmol/L).Conclusion:Ginsenoside Rb1 selectively inhibits the activity of L-type voltage-gated calcium channels,without affecting the N-type or P/Q-type Ca2+ channels in hippocampal neurons,cAMP-PKA signaling pathway is not involved in this effect.

  9. Changes in neuronal excitability by activated microglia: Differential Na+ current up-regulation in pyramid-shaped and bipolar neurons by TNF-α and IL-18

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    Lars eKlapal

    2016-03-01

    Full Text Available Microglia are activated during pathological events in the brain and are capable of releasing various types of inflammatory cytokines. Here we demonstrate that the addition of 5% microglia activated by 1 µg/ml lipopolysaccharides (LPS to hippocampal cultures up-regulates Na+ current densities (INavD of bipolar as well as pyramid-shaped neurons, thereby increasing their excitability. Deactivation of microglia by the addition of 10 ng/ml transforming growth factor-β (TGF-β decreases INavD below control levels suggesting that the residual activated microglial cells influence neuronal excitability in control cultures. Preincubation of hippocampal cultures with 10 ng/ml tumor necrosis factor-α (TNF-α, a major cytokine released by activated microglia, up-regulated INavD significantly by ~30% in bipolar cells, whereas in pyramid-shaped cells the up-regulation only reached an increase of ~14%. Incubation of the cultures with antibodies against either TNF-receptor 1 or 2 blocked the up-regulation of INavD in bipolar cells, whereas in pyramid-shaped cells increases in INavD were exclusively blocked by antibodies against TNF-receptor 2, suggesting that both cell types respond differently to TNF-α exposure. Since additional cytokines, such as interleukin-18 (IL-18, are released from activated microglia we tested potential effects of IL-18 on INavD in both cell types. Exposure to 5-10 ng/ml IL-18 for 4 days increased INavD in both pyramid-shaped as well as bipolar neurons, albeit the dose-response curves were shifted to lower concentrations in bipolar cells. Our results suggest that by secretion of cytokines microglial cells up-regulate Na+ current densities in bipolar and pyramid-shaped neurons to some extent differentially. Depending on the exact cytokine composition and concentration released this could change the balance between the activity of inhibitory bipolar and excitatory pyramid-shaped cells. Since bipolar cells show a larger up-regulation of

  10. Changes in Neuronal Excitability by Activated Microglia: Differential Na(+) Current Upregulation in Pyramid-Shaped and Bipolar Neurons by TNF-α and IL-18.

    Science.gov (United States)

    Klapal, Lars; Igelhorst, Birte A; Dietzel-Meyer, Irmgard D

    2016-01-01

    Microglia are activated during pathological events in the brain and are capable of releasing various types of inflammatory cytokines. Here, we demonstrate that the addition of 5% microglia activated by 1 μg/ml lipopolysaccharides (LPS) to hippocampal cultures upregulates Na(+) current densities (INavD) of bipolar as well as pyramid-shaped neurons, thereby increasing their excitability. Deactivation of microglia by the addition of 10 ng/ml transforming growth factor-β (TGF-β) decreases INavD below control levels suggesting that the residual activated microglial cells influence neuronal excitability in control cultures. Preincubation of hippocampal cultures with 10 ng/ml tumor necrosis factor-α (TNF-α), a major cytokine released by activated microglia, upregulated INavD significantly by ~30% in bipolar cells, whereas in pyramid-shaped cells, the upregulation only reached an increase of ~14%. Incubation of the cultures with antibodies against either TNF-receptor 1 or 2 blocked the upregulation of INavD in bipolar cells, whereas in pyramid-shaped cells, increases in INavD were exclusively blocked by antibodies against TNF-receptor 2, suggesting that both cell types respond differently to TNF-α exposure. Since additional cytokines, such as interleukin-18 (IL-18), are released from activated microglia, we tested potential effects of IL-18 on INavD in both cell types. Exposure to 5-10 ng/ml IL-18 for 4 days increased INavD in both pyramid-shaped as well as bipolar neurons, albeit the dose-response curves were shifted to lower concentrations in bipolar cells. Our results suggest that by secretion of cytokines, microglial cells upregulate Na(+) current densities in bipolar and pyramid-shaped neurons to some extent differentially. Depending on the exact cytokine composition and concentration released, this could change the balance between the activity of inhibitory bipolar and excitatory pyramid-shaped cells. Since bipolar cells show a larger upregulation of

  11. 钾通道阻断剂4-氨基吡啶诱导海马CA1锥体神经元钙瞬变%Calcium transient of CA1 pyramidal neurons induced by potassium blocker 4-aminopyridine in acute hippocampal slices

    Institute of Scientific and Technical Information of China (English)

    苏涛; 丛文东; 廖卫平

    2011-01-01

    Objective To investigate the calcium transient of CA1 pyramidal neurons induced by potassium blocker 4-aminopyridine (4-AP) in acute hippocampal slices to explore the relation between potassium channel function and calcium transient, and their mechanism. Methods Fluorescent probe was employed to mark the hippocampai neurons in acute brain slices of rats; confocal microscopy was used to perform calcium imaging to observe the influences of different concentrations of 4-AP and perfusate with/without calcium on calcium transient of CA1 pyramidal neurons. Results The response of [Ca2+]I to lower concentration of 4-AP (<15 mmol/L) was in a dose-dependent manner (r2=0.910, P=0.000); the higher the concentration of 4-AP (20-80 mmol/L), the lower the peak level of calcium transient. The latency and amplitude of calcium transient induced by 4-AP were obviously reduced when the extracellular condition was switched to an absence of calcium, which was significantly different as compared with that with calcium (P<0.05). Conclusion Blockade of potassium channels with 4-AP can increase [Ca2+]I in the hippocampal pyramidal neurons of acute slices. The increase of [Ca2+]1 to 4-AP could be ascribe to calcium release from intracellular stores and calcium influx from extracellular matrix.%目的 研究4-氨基吡啶(4-AP)诱导的急性脑片海马CA1锥体神经元钙瞬变现象,探讨钾通道功能与钙瞬变的关系及可能机制.方法 荧光探针标记正常大鼠急性脑片海马神经元.共聚焦显微镜技术进行钙成像,观察不同浓度4-AP及细胞灌流液条件对神经元钙瞬变的影响.结果 低浓度(<15 mmol/L)4-AP诱导的钙瞬变峰值与剂量呈线性相关(r2=0.910,P=0.000),高浓度(20~80 mmol/L)4-AP诱导的钙瞬变峰值随浓度增高而下降.在无钙灌流液条件下,4-AP诱导的钙瞬变峰值水平下降,达峰时间延长,与含钙灌流液比较差异有统计学意义(P<0.05).结论 4-AP可诱导急性脑片海马CA1锥体神经

  12. Network dynamics of cultured hippocampal neurons in a multi-electrode array

    Science.gov (United States)

    Taguchi, Takahisa; Kudoh, Suguru N.

    2005-02-01

    The neurons in dissociation culture autonomously re-organized their functional neuronal networks, after the process for elongating neurites and establishing synaptic connections. The spatio-temporal patterns of activity in the networks might be a reflection of functional neuron assemblies. The functional connections were dynamically modified by synaptic potentiation and the process may be required for reorganization of the functional group of neurons. Such neuron assemblies are critical for information processing in brain. To visualize the functional connections between neurons, we have analyzed the autonomous activity of synaptically induced action potentials in the living neuronal networks on a multi-electrode array, using "connection map analysis" that we developed for this purpose. Moreover, we designed aan original wide area covering electrode array and succeeded in recording spontaneous action potentials from wider area than commercial multi electrode arrays.

  13. The neurotoxicity of hallucinogenic amphetamines in primary cultures of hippocampal neurons.

    Science.gov (United States)

    Capela, João Paulo; da Costa Araújo, Silvana; Costa, Vera Marisa; Ruscher, Karsten; Fernandes, Eduarda; Bastos, Maria de Lourdes; Dirnagl, Ulrich; Meisel, Andreas; Carvalho, Félix

    2013-01-01

    3,4-Methylenedioxymethamphetamine (MDMA or "Ecstasy") and 2,5-dimethoxy-4-iodoamphetamine hydrochloride (DOI) are hallucinogenic amphetamines with addictive properties. The hippocampus is involved in learning and memory and seems particularly vulnerable to amphetamine's neurotoxicity. We evaluated the neurotoxicity of DOI and MDMA in primary neuronal cultures of hippocampus obtained from Wistar rat embryos (E-17 to E-19). Mature neurons after 10 days in culture were exposed for 24 or 48 h either to MDMA (100-800 μM) or DOI (10-100 μM). Both the lactate dehydrogenase (LDH) release and the tetrazolium-based (MTT) assays revealed a concentration- and time-dependent neuronal death and mitochondrial dysfunction after exposure to both drugs. Both drugs promoted a significant increase in caspase-8 and caspase-3 activities. At concentrations that produced similar levels of neuronal death, DOI promoted a higher increase in the activity of both caspases than MDMA. In the mitochondrial fraction of neurons exposed 24h to DOI or MDMA, we found a significant increase in the 67 kDa band of apoptosis inducing factor (AIF) by Western blot. Moreover, 24h exposure to DOI promoted an increase in cytochrome c in the cytoplasmatic fraction of neurons. Pre-treatment with an antibody raised against the 5-HT(2A)-receptor (an irreversible antagonist) greatly attenuated neuronal death promoted by 48 h exposure to DOI or MDMA. In conclusion, hallucinogenic amphetamines promoted programmed neuronal death involving both the mitochondria machinery and the extrinsic cell death key regulators. Death was dependent, at least in part, on the stimulation of the 5-HT(2A)-receptors.

  14. Large-scale, high-resolution multielectrode-array recording depicts functional network differences of cortical and hippocampal cultures.

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    Shinya Ito

    Full Text Available Understanding the detailed circuitry of functioning neuronal networks is one of the major goals of neuroscience. Recent improvements in neuronal recording techniques have made it possible to record the spiking activity from hundreds of neurons simultaneously with sub-millisecond temporal resolution. Here we used a 512-channel multielectrode array system to record the activity from hundreds of neurons in organotypic cultures of cortico-hippocampal brain slices from mice. To probe the network structure, we employed a wavelet transform of the cross-correlogram to categorize the functional connectivity in different frequency ranges. With this method we directly compare, for the first time, in any preparation, the neuronal network structures of cortex and hippocampus, on the scale of hundreds of neurons, with sub-millisecond time resolution. Among the three frequency ranges that we investigated, the lower two frequency ranges (gamma (30-80 Hz and beta (12-30 Hz range showed similar network structure between cortex and hippocampus, but there were many significant differences between these structures in the high frequency range (100-1000 Hz. The high frequency networks in cortex showed short tailed degree-distributions, shorter decay length of connectivity density, smaller clustering coefficients, and positive assortativity. Our results suggest that our method can characterize frequency dependent differences of network architecture from different brain regions. Crucially, because these differences between brain regions require millisecond temporal scales to be observed and characterized, these results underscore the importance of high temporal resolution recordings for the understanding of functional networks in neuronal systems.

  15. Novel bio-spectroscopic imaging reveals disturbed protein homeostasis and thiol redox with protein aggregation prior to hippocampal CA1 pyramidal neuron death induced by global brain ischemia in the rat.

    Science.gov (United States)

    Hackett, Mark J; Smith, Shari E; Caine, Sally; Nichol, Helen; George, Graham N; Pickering, Ingrid J; Paterson, Phyllis G

    2015-12-01

    occur in the same CA1 pyramidal neurons 1 day after global ischemia. Further, analysis of serial tissue sections using X-ray absorption spectroscopy at the sulfur K-edge has revealed that CA1 pyramidal neurons have increased disulfide levels, a direct indicator of oxidative stress, at this time point. These changes at 1 day after ischemia precede a massive increase in aggregated protein and disulfide levels concomitant with loss of neuron integrity 2 days after ischemia. Therefore, this study has provided direct support for a correlative mechanistic link in both spatial and temporal domains between oxidative stress, protein aggregation and altered protein homeostasis prior to irreparable neuron damage following global ischemia.

  16. Phenolic Compounds Protect Cultured Hippocampal Neurons against Ethanol-Withdrawal Induced Oxidative Stress

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    Marianna E. Jung

    2009-04-01

    Full Text Available Ethanol withdrawal is linked to elevated oxidative damage to neurons. Here we report our findings on the contribution of phenolic antioxidants (17β-estradiol, p-octyl-phenol and 2,6-di-tert-butyl-4-methylphenol to counterbalance sudden ethanol withdrawal-initiated oxidative events in hippocampus-derived cultured HT-22 cells. We showed that ethanol withdrawal for 4 h after 24-h ethanol treatment provoked greater levels of oxidative damage than the preceding ethanol exposure. Phenolic antioxidant treatment either during ethanol exposure or ethanol withdrawal only, however, dose-dependently reversed cellular oxidative damage, as demonstrated by the significantly enhanced cell viability, reduced malondialdehyde production and protein carbonylation, compared to untreated cells. Interestingly, the antioxidant treatment schedule had no significant impact on the observed neuroprotection. In addition, the efficacy of the three phenolic compounds was practically equipotent in protecting HT-22 cells in spite of predictions based on an in silico study and a cell free assay of lipid peroxidation. This finding implies that free-radical scavenging may not be the sole factor responsible for the observed neuroprotection and warrants further studies to establish, whether the HT-22 line is indeed a suitable model for in vitro screening of antioxidants against EW-related neuronal damage.

  17. A transcription-dependent increase in miniature EPSC frequency accompanies late-phase plasticity in cultured hippocampal neurons

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    Hofmann Frank

    2009-09-01

    Full Text Available Abstract Background The magnitude and longevity of synaptic activity-induced changes in synaptic efficacy is quantified by measuring evoked responses whose potentiation requires gene transcription to persist for more than 2-3 hours. While miniature EPSCs (mEPSCs are also increased in amplitude and/or frequency during long-term potentiation (LTP, it is not known how long such changes persist or whether gene transcription is required. Results We use whole-cell patch clamp recordings from dissociated hippocampal cultures to characterise for the first time the persistence and transcription dependency of mEPSC upregulation during synaptic potentiation. The persistence of recurrent action potential bursting in these cultures is transcription-, translation- and NMDA receptor-dependent thus providing an accessible model for long-lasting plasticity. Blockade of GABAA-receptors with bicuculline for 15 minutes induced action potential bursting in all neurons and was maintained in 50-60% of neurons for more than 6 hours. Throughout this period, the frequency but neither the amplitude of mEPSCs nor whole-cell AMPA currents was markedly increased. The transcription blocker actinomycin D abrogated, within 2 hours of burst induction, both action potential bursting and the increase in mEPSCs. Reversible blockade of action potentials during, but not after this 2 hour transcription period suppressed the increase in mEPSC frequency and the recovery of burst activity at a time point 6 hours after induction. Conclusion These results indicate that increased mEPSC frequency persists well beyond the 2 hour transcription-independent phase of plasticity in this model. This long-lasting mEPSC upregulation is transcription-dependent and requires ongoing action potential activity during the initial 2 hour period but not thereafter. Thus mEPSC upregulation may underlie the long term, transcription-dependent persistence of action potential bursting. This provides mechanistic

  18. Hippocampal GABAergic interneurons coexpressing alpha7-nicotinic receptors and connexin-36 are able to improve neuronal viability under oxygen-glucose deprivation.

    Science.gov (United States)

    Voytenko, L P; Lushnikova, I V; Savotchenko, A V; Isaeva, E V; Skok, M V; Lykhmus, O Yu; Patseva, M A; Skibo, G G

    2015-08-07

    The hippocampal interneurons are very diverse by chemical profiles and rather inconsistent by sensitivity to CI. Some hippocampal GABAergic interneurons survive certain time after ischemia while ischemia-sensitive interneurons and pyramidal neurons are damaged. GABAergic signaling, nicotinic receptors expressing α7-subunit (α7nAChRs(+)) and connexin-36 (Cx36(+), electrotonic gapjunctions protein) contradictory modulate post-ischemic environment. We hypothesized that hippocampal ischemia-resistant GABAergic interneurons coexpressing glutamate decarboxylase-67 isoform (GAD67(+)), α7nAChRs(+), Cx36(+) are able to enhance neuronal viability. To check this hypothesis the histochemical and electrophysiological investigations have been performed using rat hippocampal organotypic culture in the condition of 30-min oxygen-glucose deprivation (OGD). Post-OGD reoxygenation (4h) revealed in CA1 pyramidal layer numerous damaged cells, decreased population spike amplitude and increased pair-pulse depression. In these conditions GAD67(+) interneurons displayed the OGD-resistance and significant increase of GABA synthesis/metabolism (GAD67-immunofluorescence, mitochondrial activity). The α7nAChRs(+) and Cx36(+) co-localizations were revealed in resistant GAD67(+) interneurons. Under OGD: GABAA-receptors (GABAARs) blockade increased cell damage and exacerbated the pair-pulse depression in CA1 pyramidal layer; α7nAChRs and Cx36-channels separate blockades sufficiently decreased cell damage while interneuronal GAD67-immunofluorescence and mitochondrial activity were similar to the control. Thus, hippocampal GABAergic interneurons co-expressing α7nAChRs and Cx36 remained resistant certain time after OGD and were able to modulate CA1 neuron survival through GABAARs, α7nAChRs and Cx36-channels activity. The enhancements of the neuronal viability together with GABA synthesis/metabolism normalization suggest cooperative neuroprotective mechanism that could be used for increase in

  19. Activation of the cannabinoid type-1 receptor mediates the anticonvulsant properties of cannabinoids in the hippocampal neuronal culture models of acquired epilepsy and status epilepticus.

    Science.gov (United States)

    Blair, Robert E; Deshpande, Laxmikant S; Sombati, Sompong; Falenski, Katherine W; Martin, Billy R; DeLorenzo, Robert J

    2006-06-01

    Cannabinoids have been shown to have anticonvulsant properties, but no studies have evaluated the effects of cannabinoids in the hippocampal neuronal culture models of acquired epilepsy (AE) and status epilepticus (SE). This study investigated the anticonvulsant properties of the cannabinoid receptor agonist R(+)-[2,3-dihydro-5-methyl-3-[(morpholinyl)methyl]pyrrolol[1,2,3 de]-1,4-benzoxazinyl]-(1-naphthalenyl)methanone (WIN 55,212-2) in primary hippocampal neuronal culture models of both AE and SE. WIN 55,212-2 produced dose-dependent anticonvulsant effects against both spontaneous recurrent epileptiform discharges (SRED) (EC50 = 0.85 microM) and SE (EC50 = 1.51 microM), with total suppression of seizure activity at 3 microM and of SE activity at 5 microM. The anticonvulsant properties of WIN 55,212-2 in these preparations were both stereospecific and blocked by the cannabinoid type-1 (CB1) receptor antagonist N-(piperidin-1-yl-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamidehydrochloride (SR141716A; 1 microM), showing a CB1 receptor-dependent pathway. The inhibitory effect of WIN 55,212-2 against low Mg2+-induced SE is the first observation in this model of total suppression of SE by a selective pharmacological agent. The clinically used anticonvulsants phenytoin and phenobarbital were not able to abolish low Mg2+-induced SE at concentrations up to 150 microM. The results from this study show CB1 receptor-mediated anticonvulsant effects of the cannabimimetic WIN 55,212-2 against both SRED and low Mg2+-induced SE in primary hippocampal neuronal cultures and show that these in vitro models of AE and SE may represent powerful tools to investigate the molecular mechanisms mediating the effects of cannabinoids on neuronal excitability.

  20. Climbing the Needs Pyramids

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    J. C. Lomas

    2013-08-01

    Full Text Available Abraham Maslow’s theory of human adult motivation is often represented by a pyramid image showing two proposals: First, the five needs stages in emergent order of hierarchical ascension and second, a percentage of the adult population suggested to occupy each needs tier. Specifically, Maslow proposed that adults would be motivated to satisfy their unfilled needs until they reached the hierarchy’s apex and achieved self-transcendence. Yet how adults can purposefully ascend Maslow’s pyramid through satisfying unfilled needs remains elusive. This brief article challenges this on the theory’s 70th anniversary by presenting a new image of the needs hierarchy, based on ecological design principles to support adults’ purposeful endeavors to climb the needs pyramid.

  1. Interleukin-1beta exacerbates hypoxia-induced neuronal damage, but attenuates toxicity produced by simulated ischaemia and excitotoxicity in rat organotypic hippocampal slice cultures.

    Science.gov (United States)

    Pringle, A K; Niyadurupola, N; Johns, P; Anthony, D C; Iannotti, F

    2001-06-01

    Using organotypic hippocampal slice cultures we have investigated the actions of Interleukin-1 (IL-1) in a number of injury paradigms. Low concentrations of IL-1 potentiated hypoxia-induced neurodegeneration whilst high concentrations had no effect. In contrast, higher concentrations of IL-1 were strongly neuroprotective in models of combined oxygen/glucose deprivation and N-methyl-D-aspartate toxicity, but no potentiation was observed at low IL-1 concentrations. Both protective and toxic effects of IL-1 were fully antagonized by IL-1 receptor antagonist. These data demonstrate that the effects of IL-1 on neuronal injury are complex, and may be directly related to the injury paradigm studied.

  2. Calcium-sensitive regulation of monoamine oxidase-A contributes to the production of peroxyradicals in hippocampal cultures: implications for Alzheimer disease-related pathology

    Directory of Open Access Journals (Sweden)

    Li XinMin

    2007-09-01

    Full Text Available Abstract Background Calcium (Ca2+ has recently been shown to selectively increase the activity of monoamine oxidase-A (MAO-A, a mitochondria-bound enzyme that generates peroxyradicals as a natural by-product of the deamination of neurotransmitters such as serotonin. It has also been suggested that increased intracellular free Ca2+ levels as well as MAO-A may be contributing to the oxidative stress associated with Alzheimer disease (AD. Results Incubation with Ca2+ selectively increases MAO-A enzymatic activity in protein extracts from mouse hippocampal HT-22 cell cultures. Treatment of HT-22 cultures with the Ca2+ ionophore A23187 also increases MAO-A activity, whereas overexpression of calbindin-D28K (CB-28K, a Ca2+-binding protein in brain that is greatly reduced in AD, decreases MAO-A activity. The effects of A23187 and CB-28K are both independent of any change in MAO-A protein or gene expression. The toxicity (via production of peroxyradicals and/or chromatin condensation associated with either A23187 or the AD-related β-amyloid peptide, which also increases free intracellular Ca2+, is attenuated by MAO-A inhibition in HT-22 cells as well as in primary hippocampal cultures. Conclusion These data suggest that increases in intracellular Ca2+ availability could contribute to a MAO-A-mediated mechanism with a role in AD-related oxidative stress.

  3. Selective regulation of axonal growth from developing hippocampal neurons by tumor necrosis factor superfamily member APRIL☆

    Science.gov (United States)

    Osório, Catarina; Chacón, Pedro J.; White, Matthew; Kisiswa, Lilian; Wyatt, Sean; Rodríguez-Tébar, Alfredo; Davies, Alun M.

    2014-01-01

    APRIL (A Proliferation-Inducing Ligand, TNFSF13) is a member of the tumor necrosis factor superfamily that regulates lymphocyte survival and activation and has been implicated in tumorigenesis and autoimmune diseases. Here we report the expression and first known activity of APRIL in the nervous system. APRIL and one of its receptors, BCMA (B-Cell Maturation Antigen, TNFRSF17), are expressed by hippocampal pyramidal cells of fetal and postnatal mice. In culture, these neurons secreted APRIL, and function-blocking antibodies to either APRIL or BCMA reduced axonal elongation. Recombinant APRIL enhanced axonal elongation, but did not influence dendrite elongation. The effect of APRIL on axon elongation was inhibited by anti-BCMA and the expression of a signaling-defective BCMA mutant in these neurons, suggesting that the axon growth-promoting effect of APRIL is mediated by BCMA. APRIL promoted phosphorylation and activation of ERK1, ERK2 and Akt and serine phosphorylation and inactivation of GSK-3β in cultured hippocampal pyramidal cells. Inhibition of MEK1/MEK2 (activators of ERK1/ERK2), PI3-kinase (activator of Akt) or Akt inhibited the axon growth-promoting action of APRIL, as did pharmacological activation of GSK-3β and the expression of a constitutively active form of GSK-3β. These findings suggest that APRIL promotes axon elongation by a mechanism that depends both on ERK signaling and PI3-kinase/Akt/GSK-3β signaling. PMID:24444792

  4. Neuregulin Directly Decreases Voltage-Gated Sodium Current in Hippocampal ErbB4-Expressing Interneurons

    OpenAIRE

    Janssen, Megan J.; Leiva-Salcedo, Elias; Buonanno, Andres

    2012-01-01

    The Neuregulin 1 (NRG1)/ErbB4 signaling pathway has been genetically and functionally implicated in the etiology underlying schizophrenia, and in the regulation of glutamatergic pyramidal neuron function and plasticity. However, ErbB4 receptors are expressed in subpopulations of GABAergic interneurons, but not in hippocampal or cortical pyramidal neurons, indicating that NRG1 effects on principal neurons are indirect. Consistent with these findings, NRG1 effects on hippocampal long-term poten...

  5. Oxygen/Glucose Deprivation and Reperfusion Cause Modifications of Postsynaptic Morphology and Activity in the CA3 Area of Organotypic Hippocampal Slice Cultures.

    Science.gov (United States)

    Jung, Yeon Joo; Suh, Eun Cheng; Lee, Kyung Eun

    2012-12-01

    Brain ischemia leads to overstimulation of N-methyl-D-aspartate (NMDA) receptors, referred as excitotoxicity, which mediates neuronal cell death. However, less attention has been paid to changes in synaptic activity and morphology that could have an important impact on cell function and survival following ischemic insult. In this study, we investigated the effects of reperfusion after oxygen/glucose deprivation (OGD) not only upon neuronal cell death, but also on ultrastructural and biochemical characteristics of postsynaptic density (PSD) protein, in the stratum lucidum of the CA3 area in organotypic hippocampal slice cultures. After OGD/reperfusion, neurons were found to be damaged; the organelles such as mitochondria, endoplasmic reticulum, dendrites, and synaptic terminals were swollen; and the PSD became thicker and irregular. Ethanolic phosphotungstic acid staining showed that the density of PSD was significantly decreased, and the thickness and length of the PSD were significantly increased in the OGD/reperfusion group compared to the control. The levels of PSD proteins, including PSD-95, NMDA receptor 1, NMDA receptor 2B, and calcium/calmodulin-dependent protein kinase II, were significantly decreased following OGD/reperfusion. These results suggest that OGD/reperfusion induces significant modifications to PSDs in the CA3 area of organotypic hippocampal slice cultures, both morphologically and biochemically, and this may contribute to neuronal cell death and synaptic dysfunction after OGD/reperfusion.

  6. Effects of droperidol on persistent sodium channel currents of pyramidal cell in hippocampal CA1 area of rats with cerebral ischemia%氟哌利多对大鼠脑缺血海马CA1区锥体细胞持续钠通道电流的影响

    Institute of Scientific and Technical Information of China (English)

    焦志华; 庄心良; 王士雷; 张一

    2005-01-01

    流.②脑缺血时海马CA1区神经元持续性钠电流的记录:缺血对照组缺血3 min时持续钠电流增加为正常情况的(1.60±0.21)倍,缺血5 min时持续钠电流增加为正常情况的(2.87±0.45)倍,差异显著(P<0.05).③不同浓度氟哌利多对脑缺血时持续性钠电流的影响:缺血对照组、氟哌利多3,10,30 μmol/L组持续钠电流的基础值分别是(77.42±15.17)pA,(87.44±21.56)pA,(84.13±20.06)pA,(80.22±19.30)pA,组间比较差异无显著性意义.缺血5min后氟哌利多3,10,30μmol/L组持续性钠电流分别为(105.36±17.16)pA,(94.74±18.88)pA,(84.88±13.94)pA,明显低于缺血对照组(218.31±29.34)pA.结论:在钳制电压-105mV、刺激电压-30mV条件下,脑缺血损伤时持续性钠电流增加,氟哌利多可能通过抑制持续性钠电流的增强而发挥神经元保护作用.%BACKGROUND: Both abnormal permeability of ionic channel and disturbance of ionic balance between inside and outside nerve cell are key factors for ischemic brain injury after ischemia. Depolarization induced by activation of sodium channel is starting link for cerebral ischemic injury.OBJECTIVE: To study the effects of droperidol on persistent sodium channel currents of pyramidal cell in hippocampal CA1 area of rats with cerebral ischemia with patch clamp technique so as to analyze whether droperidol can protect cerebral ischemic injury.DESIGN: Randomized controlled animal study.SETTING: Department of Anesthesiology of the Sixth People's Hospital Affiliated to Shanghai Jiaotong University and Department of Anesthesiology of the First People's Hospital Affiliated to Shanghai Jiaotong University.MATERIALS: The experiment was carried out at the Department of Anesthesiology of the First People's Hospital Affiliated to Shanghai Jiaotong University from April 2002 to April 2003. Totally 14 SD rats, aging 10-14days, without ablactation, were selected. Two cells in hippocampal CA1area of each rat were collected, totally 28 cells were divided into 4 groups

  7. PYRAMID ROADLESS AREA, CALIFORNIA.

    Science.gov (United States)

    Armstrong, Augustus K.; Scott, Douglas F.

    1984-01-01

    A geologic and mineral survey was conducted in the Pyramid Roadless Area, California. The area contains mineral showings, but no mineral-resource potential was identified during our studies. Three granodiorite samples on the west side of the roadless area contained weakly anomalous concentrations of uranium. Two samples of roof-pendant rocks, one metasedimentary rock and one metavolcanic rock, contain low concentrations of copper, and of copper and molybdenum, respectively. Although none was identified, the geologic terrane is permissive for mineral occurrences and large-scale, detailed geologic mapping of the areas of metasedimentary and metavolcanic roof pendants in the Pyramid Roadless Area could define a mineral-resource potential for tungsten and precious metals.

  8. Building the next pyramid

    CERN Document Server

    West, Joseph; Waters, Kevin; Ward, Stephen; Ward, Tia

    2015-01-01

    The results of experimental tests of a novel method for moving large (pyramid construction size) stone blocks by rolling them are presented. The method is implemented by tying 12 identical rods of appropriately chosen radius to the faces of the block forming a rough dodecagon prism. Experiments using a 1,000 kg block show that it can be moved across level open ground with a dynamic coefficient of friction of less than 0.06. This value is a factor of five lower than that obtained for dragging the block, and the best values reported for dragging by others, at 0.3. the results are more dramatic than those obtained on smaller scale experiments on a 29.6 kg block, also reported here. For full scale pyramid blocks, the wooden "rods" woudl need to be posts of order 30 cm in diameter, similar in size to those used as masts on ships in the Nile.

  9. Climbing the Needs Pyramids

    OpenAIRE

    J. C. Lomas

    2013-01-01

    Abraham Maslow’s theory of human adult motivation is often represented by a pyramid image showing two proposals: First, the five needs stages in emergent order of hierarchical ascension and second, a percentage of the adult population suggested to occupy each needs tier. Specifically, Maslow proposed that adults would be motivated to satisfy their unfilled needs until they reached the hierarchy’s apex and achieved self...

  10. Climbing the Needs Pyramids

    OpenAIRE

    J. C. Lomas

    2013-01-01

    Abraham Maslow’s theory of human adult motivation is often represented by a pyramid image showing two proposals: First, the five needs stages in emergent order of hierarchical ascension and second, a percentage of the adult population suggested to occupy each needs tier. Specifically, Maslow proposed that adults would be motivated to satisfy their unfilled needs until they reached the hierarchy’s apex and achieved self...

  11. Imaging the Cheops Pyramid

    CERN Document Server

    Bui, H D

    2012-01-01

    In this book Egyptian Archeology  and Mathematics meet. The author is an expert in theories and applications in Solid Mechanics and Inverse Problems, a former professor at Ecole Polytechnique and now works with Electricité de France on maintenance operations on nuclear power plants. In the Autumn of 1986, after the end of the operation on the King’s chamber conducted under the Technological and Scientific Sponsorship of EDF, to locate a cavity, he was called to solve a mathematical inverse problem, to find the unknown tomb of the King and the density structure of the whole pyramid based on measurements of microgravity made inside and outside of the pyramid. This book recounts the various search operations on the pyramid of Cheops made at the request of the Egyptian and French authorities in 1986-1987. After the premature end of the Cheops operation in the Autumn of 1986, following the fiasco of unsuccessful drillings in the area suspected by both architects G. Dormion and J.P. Goidin and microgravity aus...

  12. Tau kinase inhibitors protect hippocampal synapses despite of insoluble tau accumulation.

    Science.gov (United States)

    Hinners, Ina; Hill, Anika; Otto, Ulrike; Michalsky, Anke; Mack, Till G A; Striggow, Frank

    2008-03-01

    A better understanding of the cellular and molecular pathomechanisms of Alzheimer's disease (AD) is a prerequisite for the development of efficient treatments. We have used a novel assay system based on virus-transduced organotypic hippocampal slice cultures that mimics important aspects of tau-driven AD pathology in a short time frame. Human tau P301L, when expressed in pyramidal neurons of hippocampal slice cultures, was increasingly phosphorylated at several disease-relevant epitopes, leading to progressive neuronal dystrophy and formation of RIPA-insoluble tau. AD-like tau hyperphosphorylation was reduced by the tau kinase inhibitors lithium and SRN-003-556, but RIPA-insoluble tau remained unaffected after treatment with any of these substances. Only SRN-003-556 was able to protect hippocampal neurons from synaptic damage that was presumably caused by a toxic soluble tau fraction. These data provide first mechanistic insights towards the functional benefits of SRN-003-556 that have been observed in vivo.

  13. Ethanol impairs muscarinic receptor-induced neuritogenesis in rat hippocampal slices: Role of astrocytes and extracellular matrix proteins.

    Science.gov (United States)

    Giordano, Gennaro; Guizzetti, Marina; Dao, Khoi; Mattison, Hayley A; Costa, Lucio G

    2011-12-01

    In an in vitro co-culture system of astrocytes and neurons, stimulation of cholinergic muscarinic receptors in astrocytes had been shown to cause neuritogenesis in hippocampal neurons, and this effect was inhibited by ethanol. The present study sought to confirm these earlier findings in a more complex system, in vitro rat hippocampal slices in culture. Exposure of hippocampal slices to the cholinergic agonist carbachol (1mM for 24h) induced neurite outgrowth in hippocampal pyramidal neurons, which was mediated by activation of muscarinic M3 receptors. Specifically, carbachol induced a >4-fold increase in the length of the longest neurite, and a 4-fold increase in the length of minor neurites and in the number of branches. Co-incubation of carbachol with ethanol (50mM) resulted in significant inhibition of the effects induced by carbachol on all parameters measured. Neurite outgrowth in CNS neurons is dependent on various permissive factors that are produced and released by glial cells. In hippocampal slices carbachol increased the levels of two extracellular matrix protein, fibronectin and laminin-1, by 1.6-fold, as measured by Western blot. Co-incubation of carbachol with ethanol significantly inhibited these increases. Carbachol-induced increases in levels of extracellular matrix proteins were antagonized by a M3 muscarinic receptor antagonist. Furthermore, function-blocking fibronectin or laminin-1 antibodies antagonized the effect of carbachol on neurite outgrowth. These results indicate that in hippocampal slices stimulation of muscarinic M3 receptors induces neurite outgrowth, which is mediated by fibronectin and laminin-1, two extracellular matrix proteins released by astrocytes. By decreasing fibronectin and laminin levels ethanol prevents carbachol-induced neuritogenesis. These findings highlight the importance of glial-neuronal interactions as important targets in the developmental neurotoxicity of alcohol.

  14. Neuroprotective property of low molecular weight fraction from B. jararaca snake venom in H2O2-induced cytotoxicity in cultured hippocampal cells.

    Science.gov (United States)

    Querobino, Samyr Machado; Carrettiero, Daniel Carneiro; Costa, Maricilia Silva; Alberto-Silva, Carlos

    2017-04-01

    In central nervous system cells, low molecular weight fractions (LMWF) from snake venoms can inhibit changes in mitochondrial membrane permeability, preventing the diffusion of cytochrome c to the cytoplasm, inhibiting the activation of pro-apoptotic factors. Here, we evaluated the neuroprotective activity of LMWF from Bothrops jararaca (Bj) snake venom in H2O2-induced cytotoxicity in cultured hippocampal cells. SDS-PAGE, FT-IR and MALDI-TOF analysis of LMWF (<14 kDa) confirmed the absence of high-molecular-weight proteins in the fraction. LMWF did not present cytotoxicity in all concentrations and time tested by MTT assay. Neuroprotection was evaluated in cells pretreated with LMWF for 4 h prior to the addition of 50 μM H2O2 for 20 h. We demonstrated that LMWF reduced the argininosuccinate synthase (AsS) and superoxide dismutase (SOD1) expressions, suggesting that this fraction as an effective neuroprotective compound that could increase the hippocampal cells viability by attenuation of oxidative stress. In addition, LMWF protects against apoptosis induced by H2O2, reducing the expression of caspase-3 and caspase-8. Overall, this study opens new perspectives for the identification of new molecules for the development of drugs applied to the treatment of neurodegenerative diseases.

  15. The metabotropic glutamate receptor agonist 1S,3R-ACPD stimulates and modulates NMDA receptor mediated excitotoxicity in organotypic hippocampal slice cultures

    DEFF Research Database (Denmark)

    Blaabjerg, M; Kristensen, Bjarne Winther; Bonde, C;

    2001-01-01

    The potential toxic effects of the metabotropic glutamate receptor agonist (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid (ACPD) and its interactions with the N-methyl-D-aspartate (NMDA) receptor were studied in hippocampal brain slice cultures, using densitometric measurements of the cellular....... The neurodegeneration induced by 2 mM ACPD was completely abolished by addition of 10 microM of the NMDA receptor antagonist (5R,10S)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine (MK-801), while 20 microM of the 2-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA)/kainic acid receptor antagonist...... of metabotropic glutamate receptors with ACPD at concentrations of 2 mM or higher induces a distinct subfield-related and time and concentration dependent pattern of hippocampal degeneration, and that ACPD at subtoxic concentrations modulates NMDA-induced excitotoxicity through the mGluR5 receptor in a time...

  16. Long-Term Lithium Treatment Increases cPLA2 and iPLA2 Activity in Cultured Cortical and Hippocampal Neurons

    Directory of Open Access Journals (Sweden)

    Vanessa de Jesus De-Paula

    2015-11-01

    Full Text Available Background: Experimental evidence supports the neuroprotective properties of lithium, with implications for the treatment and prevention of dementia and other neurodegenerative disorders. Lithium modulates critical intracellular pathways related to neurotrophic support, inflammatory response, autophagy and apoptosis. There is additional evidence indicating that lithium may also affect membrane homeostasis. Objective: To investigate the effect of lithium on cytosolic phospholipase A2 (PLA2 activity, a key player on membrane phospholipid turnover which has been found to be reduced in blood and brain tissue of patients with Alzheimer’s disease (AD. Methods: Primary cultures of cortical and hippocampal neurons were treated for 7 days with different concentrations of lithium chloride (0.02 mM, 0.2 mM and 2 mM. A radio-enzymatic assay was used to determine the total activity of PLA2 and two PLA2 subtypes: cytosolic calcium-dependent (cPLA2; and calcium-independent (iPLA2. Results: cPLA2 activity increased by 82% (0.02 mM; p = 0.05 and 26% (0.2 mM; p = 0.04 in cortical neurons and by 61% (0.2 mM; p = 0.03 and 57% (2 mM; p = 0.04 in hippocampal neurons. iPLA2 activity was increased by 7% (0.2 mM; p = 0.04 and 13% (2 mM; p = 0.05 in cortical neurons and by 141% (0.02 mM; p = 0.0198 in hippocampal neurons. Conclusion: long-term lithium treatment increases membrane phospholipid metabolism in neurons through the activation of total, c- and iPLA2. This effect is more prominent at sub-therapeutic concentrations of lithium, and the activation of distinct cytosolic PLA2 subtypes is tissue specific, i.e., iPLA2 in hippocampal neurons, and cPLA2 in cortical neurons. Because PLA2 activities are reported to be reduced in Alzheimer’s disease (AD and bipolar disorder (BD, the present findings provide a possible mechanism by which long-term lithium treatment may be useful in the prevention of the disease.

  17. Long-term, repeated dose in vitro neurotoxicity of the glutamate receptor antagonist L-AP3, demonstrated in rat hippocampal slice cultures by using continuous propidium iodide incubation

    DEFF Research Database (Denmark)

    Kristensen, Bjarne W; Blaabjerg, Morten; Noraberg, Jens

    2007-01-01

    Most in vitro models are only used to assess short-term effects of test compounds. However, as demonstrated here, hippocampal slice cultures can be used for long-term studies. The test compound used was the metabotropic glutamate receptor antagonist, L(+)-2-amino-3-phosphonopropionic acid (L-AP3...

  18. 内源性大麻素对海马神经元 AMPA 受体GluR2的作用%Effect of endocannabinoids pretreatment on the expression of AMPA receptor GluR2 subunit in the hippocampal pyramidal neurons of mouse

    Institute of Scientific and Technical Information of China (English)

    刘曌宇; 高杨; 孙思斯; 陈绍洋; 王强

    2015-01-01

    ) (the solvent of 2-AG or AM251) was injected intraperitoneally in vehicle group mice. Global cerebral I/R was induced at 30 min after preconditioning by occlusion of bilateral common carotid artery for 20 min and then followed by reperfusion.Immunofluorescence and Western blot were employed to detect the expression of GluR2 in the hippocampus.Results The AMPA receptor GluR2 subunit was highly expressed in the pyramidal cell layers of hippocampal CA1.Two hours after reperfusion, global cerebral ischemia induced a marked reduction in GluR2 expression in the pyramidal neurons (P<0.05).In 2-AG group, hippocampal neuronal GluR2 expression was significantly up-regulated compared with that of I/R group (P<0.05).The GluR2 expression decreased in the AM251 +2-AG group compared with that in 2-AG group ( P <0.05 ).Conclusion Endocannabinoids preconditioning increases the expression of hippocampal neuronal AMPA receptor GluR2 via CB1R after global cerebral ischemia.

  19. Hippocampal Astrocyte Cultures from Adult and Aged Rats Reproduce Changes in Glial Functionality Observed in the Aging Brain.

    Science.gov (United States)

    Bellaver, Bruna; Souza, Débora Guerini; Souza, Diogo Onofre; Quincozes-Santos, André

    2017-05-01

    Astrocytes are dynamic cells that maintain brain homeostasis, regulate neurotransmitter systems, and process synaptic information, energy metabolism, antioxidant defenses, and inflammatory response. Aging is a biological process that is closely associated with hippocampal astrocyte dysfunction. In this sense, we demonstrated that hippocampal astrocytes from adult and aged Wistar rats reproduce the glial functionality alterations observed in aging by evaluating several senescence, glutamatergic, oxidative and inflammatory parameters commonly associated with the aging process. Here, we show that the p21 senescence-associated gene and classical astrocyte markers, such as glial fibrillary acidic protein (GFAP), vimentin, and actin, changed their expressions in adult and aged astrocytes. Age-dependent changes were also observed in glutamate transporters (glutamate aspartate transporter (GLAST) and glutamate transporter-1 (GLT-1)) and glutamine synthetase immunolabeling and activity. Additionally, according to in vivo aging, astrocytes from adult and aged rats showed an increase in oxidative/nitrosative stress with mitochondrial dysfunction, an increase in RNA oxidation, NADPH oxidase (NOX) activity, superoxide levels, and inducible nitric oxide synthase (iNOS) expression levels. Changes in antioxidant defenses were also observed. Hippocampal astrocytes also displayed age-dependent inflammatory response with augmentation of proinflammatory cytokine levels, such as TNF-α, IL-1β, IL-6, IL-18, and messenger RNA (mRNA) levels of cyclo-oxygenase 2 (COX-2). Furthermore, these cells secrete neurotrophic factors, including glia-derived neurotrophic factor (GDNF), brain-derived neurotrophic factor (BDNF), S100 calcium-binding protein B (S100B) protein, and transforming growth factor-β (TGF-β), which changed in an age-dependent manner. Classical signaling pathways associated with aging, such as nuclear factor erythroid-derived 2-like 2 (Nrf2), nuclear factor kappa B (NFκ

  20. 常压高氧处理对丙戊酸钠孤独症模型鼠学习记忆能力及海马CA1区锥体细胞形态学的影响%Effects of normobaric hyperoxia on the learning and memory abilities of valproic acid autism model rats and the morphology of pyramidal cells in hippocampal CA1 region

    Institute of Scientific and Technical Information of China (English)

    马遥; 衣明纪; 李音; 付伟伟; 万金娥

    2012-01-01

    test at the 28th day after birth,40 male VPA autism model rats were randomly selected 20 only and divided into normobaric hyperoxia model group (group A,n =10),atmospheric air model group (group B,n =10).Normal control groups were obtained in male offspring of Wistar rats that received intraperitoneal injection of equivalent physiological saline at the same period pregnancy.(group C,n =10).Rats in group A were treated with oxygen for 1 h per day and lasted 1 week;group B and C were treated with normal air.The learning and memory abilities of three groups were assessed at the 35th day after birth.The immunohistochemistry methods and image analysis were used to observe the pyramidal cells of autism model rats in hippocampal CA1 region.The effect of normobaric hyperoxia therapy on pyramidal cell of autism model rats in hippocampal CA1 region were evaluated by HE staining technique.Results The trying times of group A after treatment were less than those before treatment (31.15 ± 0.99 vs 31.54 ± 0.97,t =2.739,P =0.018).The memory times were more than those before treatment (3.00± 0.58 vs 2.69 ± 0.48,t =-2.309,P =0.040).The trying times of group A after treatment were less than those in group B after treatment (P =0.016).The memory times of group A were not different from that in group B after treatment(P=0.810).The morphology of pyramidal cells in hippocampal CA1 region showed that the pyramidal cells of the autism model rats had apoptosised.The number of apoptotic cells reduced and the number of normal form cells increased after the normobaric hyperoxia intervention compared with the autism model rats.Conclusion Normobaric hyperoxia intervention can improve the learning and memory abilities of the autism model rats.The apoptosis of the pyramidal neurons in hippocampal CA1 might be reduced after the normobaric hyperoxia intervention.

  1. Event Detection by Velocity Pyramid

    OpenAIRE

    2014-01-01

    In this paper, we propose velocity pyramid for multimediaevent detection. Recently, spatial pyramid matching is proposed to in-troduce coarse geometric information into Bag of Features framework,and is eective for static image recognition and detection. In video, notonly spatial information but also temporal information, which repre-sents its dynamic nature, is important. In order to fully utilize it, wepropose velocity pyramid where video frames are divided into motionalsub-regions. Our meth...

  2. Cav 1.3 channels play a crucial role in the formation of paroxysmal depolarization shifts in cultured hippocampal neurons.

    Science.gov (United States)

    Stiglbauer, Victoria; Hotka, Matej; Ruiß, Manuel; Hilber, Karlheinz; Boehm, Stefan; Kubista, Helmut

    2017-05-01

    An increase of neuronal Cav 1.3 L-type calcium channels (LTCCs) has been observed in various animal models of epilepsy. However, LTCC inhibitors failed in clinical trials of epileptic treatment. There is compelling evidence that paroxysmal depolarization shifts (PDSs) involve Ca(2+) influx through LTCCs. PDSs represent a hallmark of epileptiform activity. In recent years, a probable epileptogenic role for PDSs has been proposed. However, the implication of the two neuronal LTCC isoforms, Cav 1.2 and Cav 1.3, in PDSs remained unknown. Moreover, Ca(2+) -dependent nonspecific cation (CAN) channels have also been suspected to contribute to PDSs. Nevertheless, direct experimental support of an important role of CAN channel activation in PDS formation is still lacking. Primary neuronal networks derived from dissociated hippocampal neurons were generated from mice expressing a dihydropyridine-insensitive Cav 1.2 mutant (Cav 1.2DHP(-/-) mice) or from Cav 1.3(-/-) knockout mice. To investigate the role of Cav 1.2 and Cav 1.3, perforated patch-clamp recordings were made of epileptiform activity, which was elicited using either bicuculline or caffeine. LTCC activity was modulated using the dihydropyridines Bay K 8644 (agonist) and isradipine (antagonist). Distinct PDS could be elicited upon LTCC potentiation in Cav 1.2DHP(-/-) neurons but not in Cav 1.3(-/-) neurons. In contrast, when bicuculline led to long-lasting, seizure-like discharge events rather than PDS, these were prolonged in Cav 1.3(-/-) neurons but not in Cav 1.2DHP(-/-) neurons. Because only the Cav 1.2 isoform is functionally coupled to CAN channels in primary hippocampal networks, PDS formation does not require CAN channel activity. Our data suggest that the LTCC requirement of PDS relates primarily to Cav 1.3 channels rather than to Cav 1.2 channels and CAN channels in hippocampal neurons. Hence, Cav 1.3 may represent a new therapeutic target for suppression of PDS development. The proposed epileptogenic role

  3. PYRAMID LAKE RENEWEABLE ENERGY PLAN

    Energy Technology Data Exchange (ETDEWEB)

    HIGH DESERT GEOCULTURE, LLC

    2009-06-06

    The Pyramid Lake Renewable Energy Plan covers these areas: energy potential (primarily focusing on geothermal resource potential, but also more generally addressing wind energy potential); renewable energy market potential; transmission system development; geothermal direct use potential; and business structures to accomplish the development objectives of the Pyramid Lake Paiute Tribe.

  4. 磷脂酰肌醇-3-激酶/蛋白激酶B信号转导通路与针刺保护癫痫继发海马神经元损伤的关系%PI 3 K/Akt Signaling Pathway Contributed to the Protective Effect of Acupuncture Intervention on Epileptic Seizure-induced Injury of Hippocampal Pyramidal Cells in Epilepsy Rats

    Institute of Scientific and Technical Information of China (English)

    杨帆; 昂文平; 沈德凯; 刘向国; 杨永清; 马允

    2013-01-01

    Objective To observe the protective effect of acupuncture stimulation on pyramidal cells in hippocampal CA 1 and CA 3 regions and to analyze the involvement of phosphatidy linositol-3-kinase (PI 3 K) /protein kinase B(PKB or Akt) signaling pathway in the acupuncture effect in epilepsy rats. Methods A total of 120 SD rats were randomly divided into normal control group, model group, LY 294002 (a specific antagonist for PI 3 K/Akt signaling) group, acupuncture + LY 294002 group and acupuncture group (n = 24 in each group, 12 for H. E. staining, and 12 for electron microscope observation). Epilepsy model was established by intraperitoneal injection of pentylenetetrazol (PTZ, 5 μL). Manual acupuncture stimulation was applied to "Baihui" (GV20) and "Dazhui" (GV 14) once daily for 5 days. Dimethyl Sulfoxide (DMSO, 5 μL, a control solvent) was given to rats of the normal, model and acupuncture groups, and LY 294002 (5 μL, dissolved in DMSO) given to rats of the LY 294002 and acupuncture+LY 294002 groups by lateral ventricular injection. Four hours and 24 h after modeling, the hippocampus tissues were sampled for observing pathological changes of CA 1 and CA 3 regions after H. E. staining under light microscope and for checking ultrastructural changes of the pyramidal cells under transmission electron microscope. Results In comparison with the normal control group, the numbers of pyramidal cells of hippocampal CA3 region in the model group were decreased significantly 4 h and 24 h after epileptic seizure (P0. 05). Findings of the light microscope and electron microscope showed that the injury severity of pyramidal cells of hippocampal CA 1 and CA 3 regions was moderate 4 h after epileptic seizure and even worse 24 h after seizure in the model group, LY 294002 group and acupuncture + LY 294002 group, but relatively lighter in the acupuncture group. These results suggested an elimination of the acupuncture effect after blocking the PI 3 K/Akt signaling pathway by lateral

  5. Hippocampal formation

    NARCIS (Netherlands)

    Cappaert, N.L.M.; van Strien, N.M.; Witter, M.P.; Paxinos, G.

    2015-01-01

    The hippocampal formation and parahippocampal region are prominent components of the rat nervous system and play a crucial role in learning, memory, and spatial navigation. Many new details regarding the entorhinal cortex have been discovered since the previous edition, and the growing interest in t

  6. Brain-derived neurotrophic factor mediates estradiol-induced dendritic spine formation in hippocampal neurons.

    Science.gov (United States)

    Murphy, D D; Cole, N B; Segal, M

    1998-09-15

    Dendritic spines are of major importance in information processing and memory formation in central neurons. Estradiol has been shown to induce an increase of dendritic spine density on hippocampal neurons in vivo and in vitro. The neurotrophin brain-derived neurotrophic factor (BDNF) recently has been implicated in neuronal maturation, plasticity, and regulation of GABAergic interneurons. We now demonstrate that estradiol down-regulates BDNF in cultured hippocampal neurons to 40% of control values within 24 hr of exposure. This, in turn, decreases inhibition and increases excitatory tone in pyramidal neurons, leading to a 2-fold increase in dendritic spine density. Exogenous BDNF blocks the effects of estradiol on spine formation, and BDNF depletion with a selective antisense oligonucleotide mimics the effects of estradiol. Addition of BDNF antibodies also increases spine density, and diazepam, which facilitates GABAergic neurotransmission, blocks estradiol-induced spine formation. These observations demonstrate a functional link between estradiol, BDNF as a potent regulator of GABAergic interneurons, and activity-dependent formation of dendritic spines in hippocampal neurons.

  7. gamma-Aminobutyric acid (GABA): a fast excitatory transmitter which may regulate the development of hippocampal neurones in early postnatal life.

    Science.gov (United States)

    Ben-Ari, Y; Tseeb, V; Raggozzino, D; Khazipov, R; Gaiarsa, J L

    1994-01-01

    The properties of neonatal GABAergic synapses were investigated in neurones of the hippocampal CA3 region. GABA, acting on GABAA receptors, provides most of the excitatory drive on immature CA3 pyramidal neurones at an early stage of development, whereas glutamatergic synapses (in particular, those mediated by AMPA receptors) are mostly quiescent. Thus, during the first postnatal week of life, bicuculline fully blocked spontaneous and evoked depolarising potentials, and GABAA receptor agonists depolarised CA3 pyramidal neurones. GABAA mediated currents also had a reduced sensitivity to benzodiazepines. In the presence of bicuculline, between P0 and P4, increasing the stimulus strength reveals an excitatory postsynaptic potential which is mostly mediated by NMDA receptors. During the same developmental period, pre- (but not post) synaptic GABAB inhibition is present. Intracellular injections of biocytin showed that the axonal network of the GABAergic interneurones is well developed at birth, whereas the pyramidal recurrent collaterals are only beginning to develop. Finally, chronic bicuculline treatment of hippocampal neurones in culture reduced the extent of neuritic arborisation, suggesting that GABA acts as a trophic factor in that period. In conclusion, it is suggested that during the first postnatal week of life, when excitatory inputs are still poorly developed, GABAA receptors provide the excitatory drive necessary for pyramidal cell outgrowth. Starting from the end of the first postnatal week of life, when excitatory inputs are well developed, GABA (acting on both GABAA and GABAB receptors) will hyperpolarise the CA3 pyramidal neurones and, as in the adult, will prevent excessive neuronal discharges. Our electrophysiological and morphological studies have shown that hippocampal GABAergic interneurones are in a unique position to modulate the development of CA3 pyramidal neurones. Developing neurones require a certain degree of membrane depolarisation, and a

  8. A threshold sodium current in pyramidal cells in rat hippocampus.

    Science.gov (United States)

    French, C R; Gage, P W

    1985-05-23

    Maintained, inward currents were activated by small depolarizations from the resting membrane potential (-50 to -60 mV) in voltage-clamped, pyramidal neurons in rat hippocampal slices. The currents were apparently Na currents as they were blocked by tetrodotoxin or removal of extracellular Na and were not affected by Cd. They showed little decrease in amplitude during prolonged depolarizations. The increase in Na conductance with depolarization was sigmoidal, with half-maximum conductance at about -50 mV, and saturated at -20 to -30 mV. This 'threshold' Na current may be involved in setting patterns of repetitive firing of action potentials.

  9. Neurosteroids block the increase in intracellular calcium level induced by Alzheimer’s β-amyloid protein in long-term cultured rat hippocampal neurons

    Directory of Open Access Journals (Sweden)

    Midori Kato-Negishi

    2008-03-01

    Full Text Available Midori Kato-Negishi1, Masahiro Kawahara21Department of Developmental Morphology, Tokyo Metropolitan Institute for Neuroscience, 2-6 Musashidai, Fuchu-shi, Tokyo 183- 8526, Japan; 2Department of Analytical Chemistry, School of Pharmaceutical Sciences, Kyushu University of Health and Welfare, 1714-1 Yoshino-cho, Nobeoka-shi, Miyazaki 882-8508, JapanAbstract: The neurotoxicity of β-amyloid protein (AβP is implicated in the etiology of Alzheimer’s disease. We previously have demonstrated that AβP forms Ca2+-permeable pores on neuronal membranes, causes a marked increase in intracellular calcium level, and leads to neuronal death. Here, we investigated in detail the features of AβP-induced changes in intracellular Ca2+ level in primary cultured rat hippocampal neurons using a multisite Ca2+- imaging system with fura-2 as a fluorescent probe. Only a small fraction of short-term cultured hippocampal neurons (ca 1 week in vitro exhibited changes in intracellular Ca2+ level after AβP exposure. However, AβP caused an acute increase in intracellular Ca2+ level in long-term cultured neurons (ca 1 month in vitro. The responses to AβP were highly heterogeneous, and immunohistochemical analysis using an antibody to AβP revealed that AβP is deposited on some but not all neurons. Considering that the disruption of Ca2+ homeostasis is the primary event in AβP neurotoxicity, substances that protect neurons from an AβP-induced intracellular Ca2+ level increase may be candidates as therapeutic drugs for Alzheimer’s disease. In line with the search for such protective substances, we found that the preadministration of neurosteroids including dehydroepiandrosterone, dehydroepiandrosterone sulfate, and pregnenolone significantly inhibits the increase in intracellular calcium level induced by AβP. Our results suggest the possible significance of neurosteroids, whose levels are reduced in the elderly, in preventing AβP neurotoxicity

  10. Leptin Induces Hippocampal Synaptogenesis via CREB-Regulated MicroRNA-132 Suppression of p250GAP

    Science.gov (United States)

    Dhar, Matasha; Zhu, Mingyan; Impey, Soren; Lambert, Talley J.; Bland, Tyler; Karatsoreos, Ilia N.; Nakazawa, Takanobu

    2014-01-01

    Leptin acts in the hippocampus to enhance cognition and reduce depression and anxiety. Cognitive and emotional disorders are associated with abnormal hippocampal dendritic spine formation and synaptogenesis. Although leptin has been shown to induce synaptogenesis in the hypothalamus, its effects on hippocampal synaptogenesis and the mechanism(s) involved are not well understood. Here we show that leptin receptors (LepRs) are critical for hippocampal dendritic spine formation in vivo because db/db mice lacking the long form of the leptin receptor (LepRb) have reduced spine density on CA1 and CA3 neurons. Leptin promotes the formation of mature spines and functional glutamate synapses on hippocampal pyramidal neurons in both dissociated and slice cultures. These effects are blocked by short hairpin RNAs specifically targeting the LepRb and are absent in cultures from db/db mice. Activation of the LepR leads to cAMP response element–binding protein (CREB) phosphorylation and initiation of CREB-dependent transcription via the MAPK kinase/Erk pathway. Furthermore, both Mek/Erk and CREB activation are required for leptin-induced synaptogenesis. Leptin also increases expression of microRNA-132 (miR132), a well-known CREB target, which is also required for leptin-induced synaptogenesis. Last, leptin suppresses the expression of p250GAP, a miR132 target, and this suppression is obligatory for leptin's effects as is the downstream target of p250GAP, Rac1. LepRs appear to be critical in vivo as db/db mice have lowered hippocampal miR132 levels and elevated p250GAP expression. In conclusion, we identify a novel signaling pathway by which leptin increases synaptogenesis through inducing CREB transcription and increasing microRNA-mediated suppression of p250GAP activity, thus removing a known inhibitor of Rac1-stimulated synaptogenesis. PMID:24877561

  11. Forebrain microglia from wild-type but not adult 5xFAD mice prevent amyloid-β plaque formation in organotypic hippocampal slice cultures.

    Science.gov (United States)

    Hellwig, Sabine; Masuch, Annette; Nestel, Sigrun; Katzmarski, Natalie; Meyer-Luehmann, Melanie; Biber, Knut

    2015-01-01

    The role of microglia in amyloid-β (Aβ) deposition is controversial. In the present study, an organotypic hippocampal slice culture (OHSC) system with an in vivo-like microglial-neuronal environment was used to investigate the potential contribution of microglia to Aβ plaque formation. We found that microglia ingested Aβ, thereby preventing plaque formation in OHSCs. Conversely, Aβ deposits formed rapidly in microglia-free wild-type slices. The capacity to prevent Aβ plaque formation was absent in forebrain microglia from young adult but not juvenile 5xFamilial Alzheimer's disease (FAD) mice. Since no loss of Aβ clearance capacity was observed in both wild-type and cerebellar microglia from 5xFAD animals, the high Aβ1-42 burden in the forebrain of 5xFAD animals likely underlies the exhaustion of microglial Aβ clearance capacity. These data may therefore explain why Aβ plaque formation has never been described in wild-type mice, and point to a beneficial role of microglia in AD pathology. We also describe a new method to study Aβ plaque formation in a cell culture setting.

  12. Cholesterol does not affect the toxicity of amyloid beta fragment but mimics its effect on MTT formazan exocytosis in cultured rat hippocampal neurons.

    Science.gov (United States)

    Abe, K; Saito, H

    1999-12-01

    It has recently been reported that methyl-beta-cyclodextrin-solubilized cholesterol protects PC12 cells from amyloid beta protein (Abeta) toxicity. To ask if this is the case in brain neurons, we investigated its effect in primary cultured rat hippocampal neurons. In basal culture conditions with no addition of Abeta, methyl-beta-cyclodextrin-solubilized cholesterol at concentrations of 30-100 microM was toxic to neurons, but at concentrations of 1-10 microM promoted neuronal survival. Methyl-beta-cyclodextrin-solubilized cholesterol at 1-10 microM was also effective in protecting neurons from toxicity of 20 microM Abeta. However, these effects were all mimicked by methyl-beta-cyclodextrin alone, but not by cholesterol solubilized by dimethylsulfoxide or ethanol. The effects of methyl-beta-cyclodextrin-solubilized cholesterol on neuronal survival and Abeta toxicity are probably attributed to the action of methyl-beta-cyclodextrin, but not cholesterol. Alternatively, we found that methyl-beta-cyclodextrin-solubilized cholesterol at lower concentrations ( > 10 nM) inhibited cellular reduction of 3-(4,5-dimethylthiazol-2-yl)-2.5-diphenyltetrazolium bromide (MTT) by promoting the exocytosis of MTT formazan. This effect was shared by dimethylsulfoxide- or ethanol-solubilized cholesterol, but not by methyl-beta-cyclodextrin, supporting that it is attributed to the action of cholesterol. These results suggest that cholesterol does not protect neurons from Abeta toxicity, or rather inhibits cellular MTT reduction in a similar manner to Abeta.

  13. Homeostatic regulation of gephyrin scaffolds and synaptic strength at mature hippocampal GABAergic postsynapses.

    Science.gov (United States)

    Vlachos, Andreas; Reddy-Alla, Suneel; Papadopoulos, Theofilos; Deller, Thomas; Betz, Heinrich

    2013-11-01

    Gephyrin is a scaffolding protein important for the postsynaptic clustering of inhibitory neurotransmitter receptors. Here, we investigated the properties of gephyrin scaffolds at γ-aminobutyric acid- (GABA-)ergic synapses in organotypic entorhino-hippocampal cultures prepared from a transgenic mouse line, which expresses green fluorescent protein-tagged gephyrin under the control of the Thy1.2 promoter. Fluorescence recovery after photobleaching revealed a developmental stabilization of postsynaptic gephyrin clusters concomitant with an increase in cluster size and synaptic strength between 1 and 4 weeks in vitro. Prolonged treatment of the slice cultures with diazepam or a GABAA receptor antagonist disclosed a homeostatic regulation of both inhibitory synaptic strength and gephyrin cluster size and stability in 4-weeks-old cultures, whereas at 1 week in vitro, the same drug treatments modulated GABAergic postsynapse and gephyrin cluster properties following a Hebbian mode of synaptic plasticity. Our data are consistent with a model in which the postnatal maturation of the hippocampal network endows CA1 pyramidal neurons with the ability to homeostatically adjust the strength of their inhibitory postsynapses to afferent GABAergic drive by regulating gephyrin scaffold properties.

  14. Age-dependent variations in potassium sensitivity of A-currents in rat hippocampal neurons.

    Science.gov (United States)

    Klee, R; Eder, C; Ficker, E; Heinemann, U

    1997-09-01

    Hippocampal pyramidal neurons were either cultured from prenatal rats or acutely isolated from the brain of newborn and juvenile rats. The influence of lowering the concentration of the extracellular potassium concentration ([K+]o) on isolated fast transient outward K+ currents (I(A)) was studied in these neurons using the patch clamp technique in the whole cell configuration. With respect to the response of I(A) to lowering [K+]o, three types of cells were observed. The first subpopulation of neurons was characterized by a complete suppression of I(A) over the whole voltage range under potassium-free solutions (type A neurons). A second proportion of cells showed an increase of I(A) at test pulses below -0 mV and a decrease of I(A) at voltages above -0 mV (type B neurons). In a third group of neurons, amplitudes of I(A) increased at all potentials tested during omission of potassium ions from the extracellular superfusate (type C neurons). Whereas type A and type B neurons were preferentially found in freshly plated cultures and newborn rats, the majority of type C cells was detected in long-term cultures and in animals of older ages. Thus, hippocampal A-currents lose their sensitivity to extracellular potassium ions during early ontogenesis.

  15. The effect of Lead Acetate on the Nitric Oxide system in the rat Hippocampal cells: An in-vitro study

    Directory of Open Access Journals (Sweden)

    "Ghane T

    2001-05-01

    Full Text Available The mechanism by which lead may cause a perturbotion in the nevous system is through the nitric oxide synthase. In this study the effect of lead acetate on the hippocampal constitutive nitric oxide production was studied. The variation in the nitric oxide production may contribute to physiological lead neurotoxicity in vivo. Different concentrations of lead acetate (10-9 to 10-6 M, wre added to cultures of hippocampal pyramidal cell obtained from one-day newborn rats. Sodium acetate was used as control. In this range of stuy viability of cells did not alter when it was compared to control (P<0.05. In another part of study, cells were obtained from one day dams whose mothers were chronically intoxicated by lead acetate. The resuts showed that neither direct exposure of normal cells mor cells obtained from latter group could show andy increase in the amount of nitric oxide. Administration of lead to the cells 10 minute before measurement showed same results.These results showed that how concentration of lead acetate can not induce nitric oxide production in the pyramidal cells

  16. Group IIA secretory phospholipase A2 stimulates exocytosis and neurotransmitter release in pheochromocytoma-12 cells and cultured rat hippocampal neurons.

    Science.gov (United States)

    Wei, S; Ong, W Y; Thwin, M M; Fong, C W; Farooqui, A A; Gopalakrishnakone, P; Hong, W

    2003-01-01

    Recent evidence shows that secretory phospholipase A2 (sPLA2) may play a role in membrane fusion and fission, and may thus affect neurotransmission. The present study therefore aimed to elucidate the effects of sPLA2 on vesicle exocytosis. External application of group IIA sPLA2 (purified crotoxin subunit B or purified human synovial sPLA2) caused an immediate increase in exocytosis and neurotransmitter release in pheochromocytoma-12 (PC12) cells, detected by carbon fiber electrodes placed near the cells, or by changes in membrane capacitance of the cells. EGTA and a specific inhibitor of sPLA2 activity, 12-epi-scalaradial, abolished the increase in neurotransmitter release, indicating that the effect of sPLA2 was dependent on calcium and sPLA2 enzymatic activity. A similar increase in neurotransmitter release was also observed in hippocampal neurons after external application of sPLA2, as detected by changes in membrane capacitance of the neurons. In contrast to external application, internal application of sPLA2 to PC12 cells and neurons produced blockade of neurotransmitter release. Our recent studies showed high levels of sPLA2 activity in the normal rat hippocampus, medulla oblongata and cerebral neocortex. The sPLA2 activity in the hippocampus was significantly increased, after kainate-induced neuronal injury. The observed effects of sPLA2 on neurotransmitter release in this study may therefore have a physiological, as well as a pathological role.

  17. Nanomolar concentrations of inorganic lead increase Ca2+ efflux and decrease intracellular free Ca2+ ion concentrations in cultured rat hippocampal neurons by a calmodulin-dependent mechanism.

    Science.gov (United States)

    Ferguson, C; Kern, M; Audesirk, G

    2000-06-01

    Inorganic lead (Pb2+) activates calmodulin, which in turn may stimulate many other cellular processes. The plasma membrane Ca2+ ATPase is a calmodulin-stimulated enzyme that plays the major role in regulating the "resting" intracellular free Ca2+ ion concentration, [Ca2+]i. We hypothesized that exposing neurons to low levels of Pb2+ would cause Pb2+ to enter the cytoplasm, and that intracellular Pb2+, by activating calmodulin, would stimulate plasma membrane Ca2+ ATPase activity, thereby increasing Ca2+ extrusion and reducing [Ca2+]i. We used the ratiometric Ca2+ indicator fura-2 to estimate changes in [Ca2+]i. In vitro calibrations of fura-2 with solutions of defined free Ca2+ and free Pb2+ concentrations showed that, at free Ca2+ concentrations from 10 nM to 1000 nM, adding Pb2+ caused either no significant change in the F340/F380 ratio (free Pb2+ concentrations from 100 fM to 1 pM) or increased the F340/F380 ratio (free Pb2+ concentrations from 5 to 50 pM). Therefore, fura-2 should be suitable for estimating Pb2+-induced decreases in [Ca2+]i, but not increases in [Ca2+]i. We exposed cultured embryonic rat hippocampal neurons to 100 nM Pb2+ for periods from 1 hour to 2 days and measured the F340/F380 ratio; the ratio decreased significantly by 9 to 16% at all time points, indicating that Pb2+ exposure decreased [Ca2+]i. In neurons loaded with 45Ca, Pb2+ exposure increased Ca2+ efflux for at least two hours; by 24 hours, Ca2+ efflux returned to control levels. Influx of 45Ca was not altered by Pb2+ exposure. Low concentrations (250 nM) of the calmodulin inhibitor calmidazolium had no effect on either 45Ca efflux or on the F340/F380 ratio in fura-loaded control neurons, but completely eliminated the increase in 45Ca efflux and decrease in F340/F380 ratio in Pb2+-exposed neurons. Zaldoride, another calmodulin inhibitor, also eliminated the decrease in F340/F380 ratio in Pb2+-exposed neurons. We conclude that Pb2+ exposure decreases [Ca2+]i and increases Ca2+ efflux

  18. Hippocampal Deletion of BDNF Gene Attenuates Gamma Oscillations in Area CA1 by Up-Regulating 5-HT3 Receptor

    OpenAIRE

    Ying Huang; Alexei Morozov

    2011-01-01

    BACKGROUND: Pyramidal neurons in the hippocampal area CA3 express high levels of BDNF, but how this BDNF contributes to oscillatory properties of hippocampus is unknown. METHODOLOGY/PRINCIPAL FINDINGS: Here we examined carbachol-induced gamma oscillations in hippocampal slices lacking BDNF gene in the area CA3. The power of oscillations was reduced in the hippocampal area CA1, which coincided with increases in the expression and activity of 5-HT3 receptor. Pharmacological block of this recept...

  19. The pyramidal capacitated vehicle routing problem

    DEFF Research Database (Denmark)

    Lysgaard, Jens

    2010-01-01

    This paper introduces the pyramidal capacitated vehicle routing problem (PCVRP) as a restricted version of the capacitated vehicle routing problem (CVRP). In the PCVRP each route is required to be pyramidal in a sense generalized from the pyramidal traveling salesman problem (PTSP). A pyramidal...

  20. The influence of neuronal density and maturation on network activity of hippocampal cell cultures: a methodological study

    National Research Council Canada - National Science Library

    Biffi, Emilia; Regalia, Giulia; Menegon, Andrea; Ferrigno, Giancarlo; Pedrocchi, Alessandra

    2013-01-01

    .... Neuronal cultures plated with different cell densities differ in number of synapses per neuron and thus in single neuron synaptic transmission, which results in a density-dependent neuronal network activity...

  1. Optical quantal analysis reveals a presynaptic component of LTP at hippocampal Schaffer-associational synapses.

    Science.gov (United States)

    Emptage, Nigel J; Reid, Christopher A; Fine, Alan; Bliss, Timothy V P

    2003-06-01

    The mechanisms by which long-term potentiation (LTP) is expressed are controversial, with evidence for both presynaptic and postsynaptic involvement. We have used confocal microscopy and Ca(2+)-sensitive dyes to study LTP at individual visualized synapses. Synaptically evoked Ca(2+) transients were imaged in distal dendritic spines of pyramidal cells in cultured hippocampal slices, before and after the induction of LTP. At most synapses, from as early as 10 min to at least 60 min after induction, LTP was associated with an increase in the probability of a single stimulus evoking a postsynaptic Ca(2+) response. These observations provide compelling evidence of a presynaptic component to the expression of early LTP at Schaffer-associational synapses. In most cases, the store-dependent evoked Ca(2+) transient in the spine was also increased after induction, a novel postsynaptic aspect of LTP.

  2. Novel nootropic dipeptide Noopept increases inhibitory synaptic transmission in CA1 pyramidal cells.

    Science.gov (United States)

    Kondratenko, Rodion V; Derevyagin, Vladimir I; Skrebitsky, Vladimir G

    2010-05-31

    Effects of newly synthesized nootropic and anxiolytic dipeptide Noopept on inhibitory synaptic transmission in hippocampal CA1 pyramidal cells were investigated using patch-clamp technique in whole-cell configuration. Bath application of Noopept (1 microM) significantly increased the frequency of spike-dependant spontaneous IPSCs whereas spike-independent mIPSCs remained unchanged. It was suggested that Noopept mediates its effect due to the activation of inhibitory interneurons terminating on CA1 pyramidal cells. Results of current clamp recording of inhibitory interneurons residing in stratum radiatum confirmed this suggestion.

  3. Quasi-Convolution Pyramidal Blurring

    OpenAIRE

    Kraus, Martin

    2008-01-01

    Efficient image blurring techniques based on the pyramid algorithm can be implemented on modern graphics hardware; thus, image blurring with arbitrary blur width is possible in real time even for large images. However, pyramidal blurring methods do not achieve the image quality provided by convolution filters; in particular, the shape of the corresponding filter kernel varies locally, which potentially results in objectionable rendering artifacts. In this work, a new analysis filter is design...

  4. Developmental changes in hippocampal associative coding.

    Science.gov (United States)

    Goldsberry, Mary E; Kim, Jangjin; Freeman, John H

    2015-03-11

    Behavioral analyses of the ontogeny of memory have shown that hippocampus-dependent learning emerges relatively late in postnatal development compared with simple associative learning. Maturation of hippocampal mnemonic mechanisms has been hypothesized to underlie the development of the later emerging learning processes. However, the role of hippocampal maturation in learning has not been examined directly. The goal of the present study was to examine developmental changes in hippocampal neuronal coding during acquisition of a hippocampus-dependent learning task. We recorded activity from CA1 pyramidal cells in rat pups while they were trained on trace eyeblink conditioning. Trace eyeblink conditioning is a Pavlovian conditioning task that involves the association of a conditioned stimulus (CS) with an unconditioned stimulus over a stimulus-free trace interval. The inclusion of the trace interval is what makes the task hippocampus dependent. In the present study, rats were trained at 21-23, 24-26, and 31-33 d of age. Previous research from our laboratory and others shows that trace conditioning begins to emerge during the third postnatal week. The results indicate that hippocampal neurons show a substantial increase in responsiveness to task-relevant events during development. Moreover, there is an age-related increase in the proportion of neurons that respond to a combination of trial events (e.g., CS and trace). Our findings indicate that the developmental emergence of hippocampally mediated learning is related to increases in the strength and complexity of CA1 associative coding.

  5. Updating the lamellar hypothesis of hippocampal organization

    Directory of Open Access Journals (Sweden)

    Robert S Sloviter

    2012-12-01

    Full Text Available In 1971, Andersen and colleagues proposed that excitatory activity in the entorhinal cortex propagates topographically to the dentate gyrus, and on through a trisynaptic circuit lying within transverse hippocampal slices or lamellae [Andersen, Bliss, and Skrede. 1971. Lamellar organization of hippocampal pathways. Exp Brain Res 13, 222-238]. In this way, a relatively simple structure might mediate complex functions in a manner analogous to the way independent piano keys can produce a nearly infinite variety of unique outputs. The lamellar hypothesis derives primary support from the lamellar distribution of dentate granule cell axons (the mossy fibers, which innervate dentate hilar neurons and area CA3 pyramidal cells and interneurons within the confines of a thin transverse hippocampal segment. Following the initial formulation of the lamellar hypothesis, anatomical studies revealed that unlike granule cells, hilar mossy cells, CA3 pyramidal cells, and Layer II entorhinal cells all form axonal projections that are more divergent along the longitudinal axis than the clearly lamellar mossy fiber pathway. The existence of pathways with translamellar distribution patterns has been interpreted, incorrectly in our view, as justifying outright rejection of the lamellar hypothesis [Amaral and Witter. 1989. The three-dimensional organization of the hippocampal formation: a review of anatomical data. Neuroscience 31, 571-591]. We suggest that the functional implications of longitudinally-projecting axons depend not on whether they exist, but on what they do. The observation that focal granule cell layer discharges normally inhibit, rather than excite, distant granule cells suggests that longitudinal axons in the dentate gyrus may mediate "lateral" inhibition and define lamellar function, rather than undermine it. In this review, we attempt a reconsideration of the evidence that most directly impacts the physiological concept of hippocampal lamellar

  6. Overcomplete steerable pyramid filters and rotation invariance

    OpenAIRE

    Greenspan, H.; Belongie, S; Goodman, R; Perona, P.; Rakshit, S.; C. H. Anderson

    1994-01-01

    A given (overcomplete) discrete oriented pyramid may be converted into a steerable pyramid by interpolation. We present a technique for deriving the optimal interpolation functions (otherwise called 'steering coefficients'). The proposed scheme is demonstrated on a computationally efficient oriented pyramid, which is a variation on the Burt and Adelson (1983) pyramid. We apply the generated steerable pyramid to orientation-invariant texture analysis in order to demonstrate its excellent rotat...

  7. Overcomplete steerable pyramid filters and rotation invariance

    OpenAIRE

    1994-01-01

    A given (overcomplete) discrete oriented pyramid may be converted into a steerable pyramid by interpolation. We present a technique for deriving the optimal interpolation functions (otherwise called 'steering coefficients'). The proposed scheme is demonstrated on a computationally efficient oriented pyramid, which is a variation on the Burt and Adelson (1983) pyramid. We apply the generated steerable pyramid to orientation-invariant texture analysis in order to demonstrate its excellent rotat...

  8. Ca²⁺/calmodulin-dependent protein kinase II contributes to hypoxic ischemic cell death in neonatal hippocampal slice cultures.

    Directory of Open Access Journals (Sweden)

    Qing Lu

    Full Text Available We have recently shown that p38MAP kinase (p38MAPK stimulates ROS generation via the activation of NADPH oxidase during neonatal hypoxia-ischemia (HI brain injury. However, how p38MAPK is activated during HI remains unresolved and was the focus of this study. Ca²⁺/calmodulin-dependent protein kinase II (CaMKII plays a key role in brain synapse development, neural transduction and synaptic plasticity. Here we show that CaMKII activity is stimulated in rat hippocampal slice culture exposed to oxygen glucose deprivation (OGD to mimic the condition of HI. Further, the elevation of CaMKII activity, correlated with enhanced p38MAPK activity, increased superoxide generation from NADPH oxidase as well as necrotic and apoptotic cell death. All of these events were prevented when CaMKII activity was inhibited with KN93. In a neonatal rat model of HI, KN93 also reduced brain injury. Our results suggest that CaMKII activation contributes to the oxidative stress associated with neural cell death after HI.

  9. Experimental investigation on spontaneously active hippocampal cultures recorded by means of high-density MEAs: analysis of the spatial resolution effects

    Directory of Open Access Journals (Sweden)

    Alessandro Maccione

    2010-05-01

    Full Text Available Based on experiments performed with high-resolution Active Pixel Sensor microelectrode arrays (APS-MEAs coupled with spontaneously active hippocampal cultures, this work investigates the spatial resolution effects of the neuroelectronic interface on the analysis of the recorded electrophysiological signals. The adopted methodology consists, first, in recording the spontaneous activity at the highest spatial resolution (inter-electrode separation of 21 µm from the whole array of 4096 microelectrodes. Then, the full resolution dataset is spatially down sampled in order to evaluate the effects on raster plot representation, array-wide spike rate (AWSR, mean firing rate (MFR and mean bursting rate (MBR. Furthermore, the effects of the array-to-network relative position are evaluated by shifting a subset of equally spaced electrodes on the entire recorded area. Results highlight that MFR and MBR are particularly influenced by the spatial resolution provided by the neuroelectronic interface. On high-resolution large MEAs, such analysis better represent the time-based parameterization of the network dynamics. Finally, this work suggest interesting capabilities of high-resolution MEAs for spatial-based analysis in dense and low-dense neuronal preparation for investigating signalling at both local and global neuronal circuitries.

  10. Aged garlic extract and its components protect cultured rat hippocampal neurons from amyloid β—protein—in—duced neuronal death

    Institute of Scientific and Technical Information of China (English)

    ItoY; KosuY

    2002-01-01

    Aged garlic extract and its components such as S-allyl-L-cysteine (SAC) and sllixin have been shown to possess various biological effects including neurotrophic activity.We characterized the neuronal death induced by amyloid β-protein (Aβ),4-hydroxynoenal (HNE),tunicamycin(TM),and trophic factor-deprivation (TFD),and ivestigated whether these garlic compounds could prevent this in cultured PC12 cells and rat hippocampal neurons.Treatment with SAC protected these cells against Aβ- and TM-induced neuronal death.SAC also attenuated the processing of procaspase-12 induced by Aβ25-35 or TM.In contrast,allixin and its analogue,DHP,afforded no protection against Aβ-induced cell death.SAC afforded no protection against HNE- and TFD-induced cell death,which has been shown to be mediated by caspase-3 dependent pathway.These results suggest that SAC protect against the neuronal cell death that is triggered by ER dysfunction.

  11. Conantokins inhibit NMDAR-dependent calcium influx in developing rat hippocampal neurons in primary culture with resulting effects on CREB phosphorylation.

    Science.gov (United States)

    Huang, Luoxiu; Balsara, Rashna D; Sheng, Zhenyu; Castellino, Francis J

    2010-10-01

    The effects of conantokin (con)-G, con-R[1-17], and con-T on ion flow through N-methyl-D-aspartate receptor (NMDAR) ion channels were determined in cultured primary rat hippocampal neurons. The potency of con-G diminished, whereas inhibition by con-R[1-17] and con-T did not change, as the neurons matured. Con-G, con-R[1-17], and con-T effectively diminished NMDA-induced Ca(2+) influx into the cells. A similar age-dependent decrease in con-G-mediated inhibition of the amplitude of spontaneous excitatory postsynaptic currents (sEPSCs) was observed, compared to con-R[1-17] and con-T. The effects of the conantokins on NMDA-induced cAMP response element-binding protein (CREB) phosphorylation in immature (DIV 9) and mature (DIV 16) neurons showed that, at DIV 9, con-G, con-R[1-17], and con-T inhibited NMDA-mediated P-CREB levels, whereas in DIV 16 neurons the conantokins did not inhibit overall levels of NMDA-induced P-CREB. In contrast, P-CREB levels were enhanced through inhibition of the protein phosphatases, PP1 and PP2B (calcineurin). This ability of conantokins to sustain CREB phosphorylation can thus enhance neuronal survival and plasticity.

  12. Updating the lamellar hypothesis of hippocampal organization.

    Science.gov (United States)

    Sloviter, Robert S; Lømo, Terje

    2012-01-01

    Andersen et al. (1971) proposed that excitatory activity in the entorhinal cortex propagates topographically to the dentate gyrus, and on through a "trisynaptic circuit" lying within transverse hippocampal "slices" or "lamellae." In this way, a relatively simple structure might mediate complex functions in a manner analogous to the way independent piano keys can produce a nearly infinite variety of unique outputs. The lamellar hypothesis derives primary support from the "lamellar" distribution of dentate granule cell axons (the mossy fibers), which innervate dentate hilar neurons and area CA3 pyramidal cells and interneurons within the confines of a thin transverse hippocampal segment. Following the initial formulation of the lamellar hypothesis, anatomical studies revealed that unlike granule cells, hilar mossy cells, CA3 pyramidal cells, and Layer II entorhinal cells all form axonal projections that are more divergent along the longitudinal axis than the clearly "lamellar" mossy fiber pathway. The existence of pathways with "translamellar" distribution patterns has been interpreted, incorrectly in our view, as justifying outright rejection of the lamellar hypothesis (Amaral and Witter, 1989). We suggest that the functional implications of longitudinally projecting axons depend not on whether they exist, but on what they do. The observation that focal granule cell layer discharges normally inhibit, rather than excite, distant granule cells suggests that longitudinal axons in the dentate gyrus may mediate "lateral" inhibition and define lamellar function, rather than undermine it. In this review, we attempt a reconsideration of the evidence that most directly impacts the physiological concept of hippocampal lamellar organization.

  13. Ablation of NMDA receptors enhances the excitability of hippocampal CA3 neurons.

    Directory of Open Access Journals (Sweden)

    Fumiaki Fukushima

    Full Text Available Synchronized discharges in the hippocampal CA3 recurrent network are supposed to underlie network oscillations, memory formation and seizure generation. In the hippocampal CA3 network, NMDA receptors are abundant at the recurrent synapses but scarce at the mossy fiber synapses. We generated mutant mice in which NMDA receptors were abolished in hippocampal CA3 pyramidal neurons by postnatal day 14. The histological and cytological organizations of the hippocampal CA3 region were indistinguishable between control and mutant mice. We found that mutant mice lacking NMDA receptors selectively in CA3 pyramidal neurons became more susceptible to kainate-induced seizures. Consistently, mutant mice showed characteristic large EEG spikes associated with multiple unit activities (MUA, suggesting enhanced synchronous firing of CA3 neurons. The electrophysiological balance between fast excitatory and inhibitory synaptic transmission was comparable between control and mutant pyramidal neurons in the hippocampal CA3 region, while the NMDA receptor-slow AHP coupling was diminished in the mutant neurons. In the adult brain, inducible ablation of NMDA receptors in the hippocampal CA3 region by the viral expression vector for Cre recombinase also induced similar large EEG spikes. Furthermore, pharmacological blockade of CA3 NMDA receptors enhanced the susceptibility to kainate-induced seizures. These results raise an intriguing possibility that hippocampal CA3 NMDA receptors may suppress the excitability of the recurrent network as a whole in vivo by restricting synchronous firing of CA3 neurons.

  14. Mitochondrial DNA copy numbers in pyramidal neurons are decreased and mitochondrial biogenesis transcriptome signaling is disrupted in Alzheimer's disease hippocampi.

    Science.gov (United States)

    Rice, Ann C; Keeney, Paula M; Algarzae, Norah K; Ladd, Amy C; Thomas, Ravindar R; Bennett, James P

    2014-01-01

    Alzheimer's disease (AD) is the major cause of adult-onset dementia and is characterized in its pre-diagnostic stage by reduced cerebral cortical glucose metabolism and in later stages by reduced cortical oxygen uptake, implying reduced mitochondrial respiration. Using quantitative PCR we determined the mitochondrial DNA (mtDNA) gene copy numbers from multiple groups of 15 or 20 pyramidal neurons, GFAP(+) astrocytes and dentate granule neurons isolated using laser capture microdissection, and the relative expression of mitochondrial biogenesis (mitobiogenesis) genes in hippocampi from 10 AD and 9 control (CTL) cases. AD pyramidal but not dentate granule neurons had significantly reduced mtDNA copy numbers compared to CTL neurons. Pyramidal neuron mtDNA copy numbers in CTL, but not AD, positively correlated with cDNA levels of multiple mitobiogenesis genes. In CTL, but not in AD, hippocampal cDNA levels of PGC1α were positively correlated with multiple downstream mitobiogenesis factors. Mitochondrial DNA copy numbers in pyramidal neurons did not correlate with hippocampal Aβ1-42 levels. After 48 h exposure of H9 human neural stem cells to the neurotoxic fragment Aβ25-35, mtDNA copy numbers were not significantly altered. In summary, AD postmortem hippocampal pyramidal neurons have reduced mtDNA copy numbers. Mitochondrial biogenesis pathway signaling relationships are disrupted in AD, but are mostly preserved in CTL. Our findings implicate complex alterations of mitochondria-host cell relationships in AD.

  15. GENE EXPRESSION CHANGES AFTER SEIZURE PRECONDITIONING IN THE THREE MAJOR HIPPOCAMPAL CELL LAYERS

    Science.gov (United States)

    Borges, Karin; Shaw, Renee; Dingledine, Raymond

    2008-01-01

    Rodents experience hippocampal damage after status epilepticus (SE) mainly in pyramidal cells while sparing the dentate granule cell layer (DGCL). Hippocampal damage was prevented in rats that had been preconditioned by brief seizures on two consecutive days before SE. To identify neuroprotective genes and biochemical pathways changed after preconditioning we compared the effect of preconditioning on gene expression in the CA1 and CA3 pyramidal and DGCLs, harvested by laser capture microscopy. In the DGCL the expression of 632 genes was altered, compared to only 151 and 58 genes in CA1 and CA3 pyramidal cell layers. Most of the differentially expressed genes regulate tissue structure and intra- and extracellular signaling, including neurotransmission. A selective upregulation of energy metabolism transcripts occurred in CA1 pyramidal cells relative to the DGCL. These results reveal a broad transcriptional response of the DGCL to preconditioning, and suggest several mechanisms underlying the neuroprotective effect of preconditioning seizures. PMID:17239605

  16. Pilocarpine-induced seizure-like activity with increased BNDF and neuropeptide Y expression in organotypic hippocampal slice cultures

    DEFF Research Database (Denmark)

    Poulsen, Frantz Rom; Jahnsen, Henrik; Blaabjerg, Morten

    2002-01-01

    with the muscarinic receptor antagonist atropine (100 microM). Regardless of dose and exposure time, the pilocarpine treatment induced very limited neuronal cell death, recorded as cellular propidium iodide uptake. Cultures exposed to 5 mM pilocarpine for up to 7 days displayed increased BDNF expression when analyzed...

  17. Non-GABA(A)-mediated effects of lindane on neurite development and intracellular free calcium ion concentration in cultured rat hippocampal neurons.

    Science.gov (United States)

    Ferguson, C A; Audesirk, G

    1995-04-01

    Changes in transmembrane Ca(2+) fluxes and intracellular free Ca(2+) ion concentrations ([Ca(2+)](in)) regulate many aspects of neurite development in cultured neurons. Lindane has been shown to increase [Ca(2+)](in) in several cell types. It was therefore hypothesized that lindane exposure would increase [Ca(2+)](in) and thereby alter neurite development in cultured rat hippocampal neurons. The study reported here showed that lindane (50-100 muM) increased [Ca(2+)](in) during short-term exposure (up to 4 hr); in contrast, with long-term exposure (24-48 hr) lindane (1-50 mum) decreased [Ca(2+)](in) significantly below control levels. Lindane decreased neurite initiation at high concentrations (25 mum or above). Lindane increased dendrite number at low concentrations (0.5-1 muM), but decreased dendrite number at high concentrations (50 mum or above). Lindane decreased axon and dendrite elongation and branching at 50 mum. Loading neurons with 1 mum 1,2-bis-(o-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid (BAPTA), a calcium chelator that partially 'clamps' [Ca(2+)](in), eliminated the effects of 50 mum lindane on [Ca(2+)](in) in short-term exposures. BAPTA did not significantly reverse the inhibition of neurite initiation or axonal elongation caused by 50 mum lindane. However, BAPTA partially reversed the inhibition of dendrite elongation and completely reversed the inhibition of axon and dendrite branching caused by 50 mum lindane. Therefore, some, but not all, of lindane's effects on neurite development may be due to changes in [Ca(2+)](in). Picrotoxin, a gamma-aminobutyric acid A (GABA(A))-associated chloride channel antagonist, had no effect on [Ca(2+)](in) or any parameters of neurite growth, suggesting that the effects of lindane on neurite development and [Ca(2+)](in) were not mediated through actions on GABA(A)-associated chloride channels.

  18. Interleukin-1beta exacerbates and interleukin-1 receptor antagonist attenuates neuronal injury and microglial activation after excitotoxic damage in organotypic hippocampal slice cultures.

    Science.gov (United States)

    Hailer, Nils P; Vogt, Cornelia; Korf, Horst-Werner; Dehghani, Faramarz

    2005-05-01

    The effects of interleukin (IL)-1beta and IL-1 receptor antagonist (IL-1ra) on neurons and microglial cells were investigated in organotypic hippocampal slice cultures (OHSCs). OHSCs obtained from rats were excitotoxically lesioned after 6 days in vitro by application of N-methyl-D-aspartate (NMDA) and treated with IL-1beta (6 ng/mL) or IL-1ra (40, 100 or 500 ng/mL) for up to 10 days. OHSCs were then analysed by bright field microscopy after hematoxylin staining and confocal laser scanning microscopy after labeling of damaged neurons with propidium iodide (PI) and fluorescent staining of microglial cells. The specificity of PI labeling of damaged neurons was validated by triple staining with neuronal and glial markers and it was observed that PI accumulated in damaged neurons only but not in microglial cells or astrocytes. Treatment of unlesioned OHSCs with IL-1beta did not induce neuronal damage but caused an increase in the number of microglial cells. NMDA lesioning alone resulted in a massive increase in the number of microglial cells and degenerating neurons. Treatment of NMDA-lesioned OHSCs with IL-1beta exacerbated neuronal cell death and further enhanced microglial cell numbers. Treatment of NMDA-lesioned cultures with IL-1ra significantly attenuated NMDA-induced neuronal damage and reduced the number of microglial cells, whereas application of IL-1ra in unlesioned OHSCs did not induce significant changes in either cell population. Our findings indicate that: (i) IL-1beta directly affects the central nervous system and acts independently of infiltrating hematogenous cells; (ii) IL-1beta induces microglial activation but is not neurotoxic per se; (iii) IL-1beta enhances excitotoxic neuronal damage and microglial activation and (iv) IL-1ra, even when applied for only 4 h, reduces neuronal cell death and the number of microglial cells after excitotoxic damage.

  19. Catalyzing new product adoption at the base of the pyramid

    NARCIS (Netherlands)

    Marinakis, Y.D.; Walsh, S.T.; Harms, R.

    2016-01-01

    One of the more perplexing of the entrepreneurial issues at the Base of the Pyramid (BoP) is how to catalyze new product adoption by BoP consumers. Because S-shaped adoption dynamics are the result of cultural transmission bias, the question can be rephrased as, how can an entrepreneur overcome conf

  20. Bidirectional Hebbian Plasticity at Hippocampal Mossy Fiber Synapses on CA3 Interneurons

    OpenAIRE

    Galván, Emilio J; Calixto, Eduardo; Barrionuevo, Germán

    2008-01-01

    Hippocampal area CA3 is critically involved in the formation of non-overlapping neuronal subpopulations (“pattern separation”) to store memory representations as distinct events. Efficient pattern separation relies on the strong and sparse excitatory input from the mossy fibers (MF) to pyramidal cells and feed-forward inhibitory interneurons. However, MF synapses on CA3 pyramidal cells undergo LTP, which, if unopposed, will degrade pattern separation as MF activation will now recruit addition...

  1. Hippocampal sharp waves: their origin and significance.

    Science.gov (United States)

    Buzsáki, G

    1986-11-29

    This study investigated the spatial distribution and cellular-synaptic generation of hippocampal sharp waves (SPW) in the dorsal hippocampus of the awake rat. Depth analyses of SPWs were performed by stepping the recording electrode in 82.5 microns increments. SPWs were present during slow wave sleep, awake immobility, drinking, grooming and eating (0.01-2/s). The largest negative SPWs were recorded from the middle part of the stratum radiatum of CA1, the stratum lucidum of CA3, the inner molecular layer of the dentate gyrus and from layer I of the subiculum, in that order. The polarity of the SPWs was positive in layers II-IV of the subiculum, in stratum oriens and stratum pyramidale of CA1 and CA3, and in the hilus of the dentate gyrus. The electrical gradients across the null zones of the field SPWs were as large as 8-14 mV/mm. SPWs were associated with population bursts of pyramidal cells and increased discharges of interneurons and granule cells. During the SPW the excitability of granule cells and pyramidal cells to afferent volleys increased considerably. Picrotoxin and atropine and aspiration lesion of the fimbria-fornix increased either the amplitude or the frequency of SPWs. Diazepam and Nembutal could completely abolish SPWs. It is suggested that: hippocampal SPWs are triggered by a population burst of CA3 pyramidal cells as a result of temporary disinhibition from afferent control; and field SPWs represent summed extracellular PSPs of CA1 and subicular pyramidal cells, and dentate granular cells induced by the Schaffer collaterals and the associational fibers of hilar cells, respectively. The relevance of the physiological SPWs to epileptic interictal spikes and long-term potentiation is discussed.

  2. Optical quantal analysis indicates that long-term potentiation at single hippocampal mossy fiber synapses is expressed through increased release probability, recruitment of new release sites, and activation of silent synapses.

    Science.gov (United States)

    Reid, Christopher A; Dixon, Don B; Takahashi, Michiko; Bliss, Tim V P; Fine, Alan

    2004-04-01

    It is generally believed that long-term potentiation (LTP) at hippocampal mossy fiber synapses between dentate granule and CA3 pyramidal cells is expressed through presynaptic mechanisms leading to an increase in quantal content. The source of this increase has remained undefined but could include enhanced probability of transmitter release at existing functional release sites or increases in the number of active release sites. We performed optical quantal analyses of transmission at individual mossy fiber synapses in cultured hippocampal slices, using confocal microscopy and intracellular fluorescent Ca(2+) indicators. Our results indicate that LTP is expressed at functional synapses by both increased probability of transmitter release and recruitment of new release sites, including the activation of previously silent synapses here visualized for the first time.

  3. [Hippocampal stroke].

    Science.gov (United States)

    Rollnik, J D; Traitel, B; Dietrich, B; Lenz, O

    2015-02-01

    Unilateral cerebral ischemia of the hippocampus is very rare. This paper reviews the literature and presents the case of a 59-year-old woman with an amnestic syndrome due to a left hippocampal stroke. The patient suffered from retrograde amnesia which was most severe over the 2 days prior to presenting and a slight anterograde amnesia. In addition, a verbal memory disorder was confirmed 1 week after admission by neurological tests. As risk factors, arterial hypertension and a relative hyper-beta lipoproteinemia were found. This case shows that unilateral amnestic stroke, e.g. in the hippocampus region, may be the cause of an amnestic syndrome and should be included in the differential diagnostics.

  4. Characterization of a novel subtype of hippocampal interneurons that express corticotropin-releasing hormone.

    Science.gov (United States)

    Hooper, Andrew; Maguire, Jamie

    2016-01-01

    A subset of corticotropin-releasing hormone (CRH) neurons was previously identified in the hippocampus with unknown function. Here we demonstrate that hippocampal CRH neurons represent a novel subtype of interneurons in the hippocampus, exhibiting unique morphology, electrophysiological properties, molecular markers, and connectivity. This subset of hippocampal CRH neurons in the mouse reside in the CA1 pyramidal cell layer and tract tracing studies using AAV-Flex-ChR2-tdTomato reveal dense back-projections of these neurons onto principal neurons in the CA3 region of the hippocampus. These hippocampal CRH neurons express both GABA and GAD67 and using in vitro optogenetic techniques, we demonstrate that these neurons make functional connections and release GABA onto CA3 principal neurons. The location, morphology, and importantly the functional connectivity of these neurons demonstrate that hippocampal CRH neurons represent a unique subtype of hippocampal interneurons. The connectivity of these neurons has significant implications for hippocampal function.

  5. PLAN FOR PERFORMANCE ADMINISTRATION IN PYRAMIDAL STRUCTURE ORGANIZATIONS

    Directory of Open Access Journals (Sweden)

    Domingo Alarcón Ortiz

    2013-11-01

    Full Text Available Performance administration has become a current strategy in evaluating management within organizations, but its implementation often lacks an action plan, resulting from the valuation of climate and leadership styles embedded in the culture of the organization. This paper proposes a model action plan for performance management, which has been implemented, executed and evaluated in pyramidal organizational structure organizations where a diagnosis of the cultural climate and leadership styles recurring in the organization have been previously made.

  6. Inhibitory microcircuit modules in hippocampal learning.

    Science.gov (United States)

    Caroni, Pico

    2015-12-01

    It has recently become possible to investigate connectivities and roles of identified hippocampal GABAergic interneurons (INs) in behaving rodents. INs targeting distinct pyramidal neuron subcompartments are recruited dynamically at defined phases of behavior and learning. They include Parvalbumin Axo-axonic and perisomatic Basket cells, and Somatostatin radiatum-oriens and oriens-lacunosum moleculare cells. Each IN is in turn either activated or inhibited upon specific behavioral and network state requirements through specific inputs and neuromodulators. Subpopulations of these principal neurons and INs interconnect selectively, suggesting selective processing and routing of alternate information streams. First canonical functional modules have emerged, which will have to be further defined and linked to identified afferents and efferents towards a circuit understanding of how hippocampal networks support behavior.

  7. Capsazepine抑制培养海马神经元网络线粒体转运%Capsazepine inhibits mitochondrial transport in cultured hippocampal neuronal networks of rat

    Institute of Scientific and Technical Information of China (English)

    付敏; 潘丽洁; 孙朝晖; 左焕琮; 谢佐平

    2009-01-01

    capsazepine(CZP)是辣椒素的合成类似物,也是野香草型瞬时感受器电位通道1(TRPV1)的选择性抑制剂.TRPV1在体内有广泛的表达谱,使CZP有广泛的作用位点.除此之外,以往的研究结果表明CZP除了作用于TRPVI外还有更复杂的信号通路.本课题研究了CZP对体外培养的大鼠海马神经元网络内线粒体转运的作用并分析其可能机制.结果显示:20 μmol/L的CZP可有效抑制原代培养海马神经元网络中的线粒体转运.CZP急性作用不引起胞内钙离子浓度的升高,也不引起细胞的凋亡.胞外更换为无外钙记录液,或者将GSK3g抑制剂SB415286与CZP共孵育,均不影响CZP对线粒体转运的抑制作用.然而,将BAPTA-AM与CZP共孵育,抑制了CZP对线粒体转运的抑制作用.本研究结果表明,CZP直接通过胞内钙信号通路影响神经元的线粒体转运,与胞外钙流或转运蛋白的磷酸化无关.%Capsazepine is a ByntlIetic analogue of capsaicin and a selective inhibitor of transient receptor potential vanilloid 1 channel (TRPV1).TRPV1 has wide expression profile,providing extensive targets for capsazepine.Evidence from previous studies showed that capsazepine acted more complex effects through other than TRPV1 signal pathway.In this study.we examined its effect and underlying mechanisms on mitochondrial transport of cultured hippecampal neurons in rats.The data showed that the number of the moving mitochondria in primarily cultured hippocampal neurons was remarkably decreased by 20 μmol/L capsazepine.Contradicted to previous study,the intracellular calcium concentration was not elevated.Capsazepine did not induce cell death in acute incubation.The inhibitory effect of capsasepine was not prevented by co-application of SB415286,the inhibitor of GSK313 or by replacing extracellular recording solution to calcium-free saline,but prevented by co-application of BAPTA-AM.These results indicated that capsazepine inhibited mitochondrial trans

  8. Differential Conditioning of Associative Synaptic Enhancement in Hippocampal Brain Slices

    Science.gov (United States)

    Kelso, Stephen R.; Brown, Thomas H.

    1986-04-01

    An electrophysiological stimulation paradigm similar to one that produces Pavlovian conditioning was applied to synaptic inputs to pyramidal neurons of hippocampal brain slices. Persistent synaptic enhancement was induced in one of two weak synaptic inputs by pairing high-frequency electrical stimulation of the weak input with stimulation of a third, stronger input to the same region. Forward (temporally overlapping) but not backward (temporally separate) pairings caused this enhancement. Thus hippocampal synapses in vitro can undergo the conditional and selective type of associative modification that could provide the substrate for some of the mnemonic functions in which the hippocampus is thought to participate.

  9. Intracellular messengers in the generation and degeneration of hippocampal neuroarchitecture.

    Science.gov (United States)

    Mattson, M P; Guthrie, P B; Kater, S B

    1988-01-01

    The actions and interactions of the neurotransmitter glutamate and the intracellular messengers calcium, cyclic AMP, and protein kinase C (PKC) in the regulation of neurite outgrowth and cell survival were examined in hippocampal pyramidal-like neurons in isolated cell culture. Low, subtoxic levels of glutamate (10-100 microM) caused the regression of dendrites but not axons; millimolar levels caused cell death. Calcium ionophore A23187 (50-100 nM) and the PKC activator phorbol-12-myristate-13-acetate (PMA; 10-50 nM) caused the regression of both axons and dendrites, whereas the adenylate cyclase activator forskolin enhanced outgrowth rates in both axons and dendrites. The effects of glutamate, A23187, PMA, and forskolin on outgrowth were mediated locally at the growth cones; dendrites were more sensitive than axons to each of these agents. High levels of A23187 (1 microM) or PMA (100 nM) significantly reduced cell survival. Co2+ and trifluoperazine each significantly reduced glutamate-induced dendritic regression and neurotoxicity suggesting that calcium influx and/or PKC activation mediated glutamate's actions. Fura-2 measurements showed that glutamate caused a rapid rise in intracellular calcium levels; this rise was prevented by Co2+. PMA and forskolin did not alter intracellular calcium levels, nor did these agents affect glutamate-induced calcium rises. Taken together, the results indicate that parallel intracellular messenger pathways that influence neurite outgrowth and cell survival are operative in hippocampal neurons; these messengers may play roles in the formation and modification of neuronal circuitry.

  10. The modulatory effect of zinc ions on voltage-gated potassium currents in cultured rat hippocampal neurons is not related to Kv1.3 channels.

    Science.gov (United States)

    Teisseyre, A; Mercik, K; Mozrzymas, J W

    2007-12-01

    We applied the whole-cell patch-clamp technique to study the influence of zinc ions (Zn(2+)) and extracellular protons at acidic pH (pH(o)) on voltage-gated potassium currents in cultured rat hippocampal neurons. The first goal of the study was to estimate whether Kv1.3 currents significantly contributed to voltage-gated potassium currents in examined cells. Then, the influence of both ions on the activity of other voltage-gated potassium currents in the neurons was examined. We examined both the total current and the delayed - rectifier component. Results obtained in both cases were not significantly different from each other. Available data argued against any significant contribution of Kv1.3 currents to the recorded currents. Nevertheless, application of Zn(2+) in the concentration range from 100 microM to 5 mM reversibly modulated the recorded currents. The activation midpoint was shifted by about 40 mV (total current) and 30 mV (delayed-rectifier current) towards positive membrane potentials and the activation kinetics were slowed significantly (2 - 3 fold) upon application of Zn(2+). The inactivation midpoint was also shifted towards positive membrane potentials, but less significantly (about 14 mV). The current amplitudes were reduced in a concentration-dependent manner to about 0.5 of the control value. The effects of Zn(2+) were saturated at the concentration of 1 mM. Raising extracellular proton concentration by lowering the pH(o) from 7.35 to 6.4 did not affect significantly the currents. Possible mechanisms underlying the observed phenomena and their possible physiological significance are discussed.

  11. Excitatory and inhibitory neurotransmitters in the generation and degeneration of hippocampal neuroarchitecture.

    Science.gov (United States)

    Mattson, M P; Kater, S B

    1989-01-30

    The possibility that excitatory and inhibitory inputs to neurons can affect the generation and degeneration of neuroarchitecture was examined in hippocampal pyramidal neurons in isolated cell culture. Dendritic outgrowth and cell survival were directly monitored in neurons exposed to: the excitatory neurotransmitter glutamate, the inhibitory transmitter GABA, anticonvulsants or combinations of these agents. Glutamate caused a graded series of changes in pyramidal neuron cytoarchitecture: a selective inhibition in dendritic outgrowth and dendritic pruning was observed with subtoxic levels of glutamate while cell death was induced by higher levels. Low levels of GABA alone or in combination with diazepam, carbamazepine, phenobarbital or phenytoin were without effect on dendrite outgrowth while higher levels caused moderate reductions in outgrowth. Neither GABA nor the anticonvulsants affected cell survival. GABA plus diazepam, phenobarbital, carbamazepine and phenytoin each significantly reduced the dendritic regression and cell death normally caused by glutamate. Elevation of extracellular K+ to 50 mM caused dendritic regression and 100 mM K+ caused cell death; these effects were greatly reduced by GABA and anticonvulsants. The calcium channel blocker Co2+ prevented the dendritic regression and cell death caused by both glutamate and K+ indicating that calcium influx was required for the neuroarchitectural responses. Taken together, these results demonstrate that neurotransmitters and neuromodulatory drugs can have direct and interactive effects on both neurite outgrowth and cell survival. Such neurotransmitter actions may play roles in both the formation and degeneration of the neuronal circuits in which they participate in information coding.

  12. Long-term rearrangements of hippocampal mossy fiber terminal connectivity in the adult regulated by experience.

    Science.gov (United States)

    Galimberti, Ivan; Gogolla, Nadine; Alberi, Stefano; Santos, Alexandre Ferrao; Muller, Dominique; Caroni, Pico

    2006-06-01

    We investigated rearrangements of connectivity between hippocampal mossy fibers and CA3 pyramidal neurons. We found that mossy fibers establish 10-15 local terminal arborization complexes (LMT-Cs) in CA3, which exhibit major differences in size and divergence in adult mice. LMT-Cs exhibited two types of long-term rearrangements in connectivity in the adult: progressive expansion of LMT-C subsets along individual dendrites throughout life, and pronounced increases in LMT-C complexities in response to an enriched environment. In organotypic slice cultures, subsets of LMT-Cs also rearranged extensively and grew over weeks and months, altering the strength of preexisting connectivity, and establishing or dismantling connections with pyramidal neurons. Differences in LMT-C plasticity reflected properties of individual LMT-Cs, not mossy fibers. LMT-C maintenance and growth were regulated by spiking activity, mGluR2-sensitive transmitter release from LMTs, and PKC. Thus, subsets of terminal arborization complexes by mossy fibers rearrange their local connectivities in response to experience and age throughout life.

  13. Thrombin modulates persistent sodium current in CA1 pyramidal neurons of young and adult rat hippocampus.

    Science.gov (United States)

    Lunko, O O; Isaev, D S; Krishtal, O O; Isaeva, E V

    2015-01-01

    Serine protease thrombin, a key factor of blood coagulation, participates in many neuronal processes important for normal brain functioning and during pathological conditions involving abnormal neuronal synchronization, neurodegeneration and inflammation. Our previous study on CA3 pyramidal neurons showed that application ofthrombin through the activation of specific protease-activated receptor 1 (PAR1) produces a significant hyperpolarizing shift of the activation of the TTX-sensitive persistent voltage-gated Na+ current (I(Nap)) thereby affecting membrane potential and seizure threshold at the network level. It was shown that PAR1 is also expressed in CA1 area of hippocampus and can be implicated in neuronal damage in this area after status epilepticus. The aim of the present study was to evaluate the effect of thrombin on I(NaP) in CA1 pyramidal neurons from adult and young rats. Using whole cell patch-clamp technique we demonstrate that thrombin application results in the hyperpolarization shift of I(NaP) activation as well as increase in the I(NaP) amplitude in both age groups. We have found that I(NaP) in pyramidal neurons of hippocampal CA 1 region is more vulnerable to the thrombin action than I(NaP) in pyramidal neurons of hippocampal CA3 region. We have also found that the immature hippocampus is more sensitive to thrombin action which emphasizes the contribution of thrombin-dependent pathway to the regulation of neuronal activity in immature brain.

  14. Apolipoprotein E isoform-dependent dendritic recovery of hippocampal neurons following activation of innate immunity

    Directory of Open Access Journals (Sweden)

    Maezawa Izumi

    2006-08-01

    Full Text Available Abstract Background Innate immune activation, including a role for cluster of differentiation 14/toll-like receptor 4 co-receptors (CD14/TLR-4 co-receptors, has been implicated in paracrine damage to neurons in several neurodegenerative diseases that also display stratification of risk or clinical outcome with the common alleles of the apolipoprotein E gene (APOE: APOE2, APOE3, and APOE4. Previously, we have shown that specific stimulation of CD14/TLR-4 with lipopolysaccharide (LPS leads to greatest innate immune response by primary microglial cultures from targeted replacement (TR APOE4 mice and greatest p38MAPK-dependent paracrine damage to neurons in mixed primary cultures and hippocampal slice cultures derived from TR APOE4 mice. In contrast, TR APOE2 astrocytes had the highest NF-kappaB activity and no neurotoxicity. Here we tested the hypothesis that direct activation of CD14/TLR-4 in vivo would yield different amounts of paracrine damage to hippocampal sector CA1 pyramidal neurons in TR APOE mice. Methods We measured in vivo changes in dendrite length in hippocampal CA1 neurons using Golgi staining and determined hippocampal apoE levels by Western blot. Neurite outgrowth of cultured primary neurons in response to astrocyte conditioned medium was assessed by measuring neuron length and branch number. Results Our results showed that TR APOE4 mice had slightly but significantly shorter dendrites at 6 weeks of age. Following exposure to intracerebroventricular LPS, there was comparable loss of dendrite length at 24 hr among the three TR APOE mice. Recovery of dendrite length over the next 48 hr was greater in TR APOE2 than TR APOE3 mice, while TR APOE4 mice had failure of dendrite regeneration. Cell culture experiments indicated that the enhanced neurotrophic effect of TR APOE2 was LDL related protein-dependent. Conclusion The data indicate that the environment within TR APOE2 mouse hippocampus was most supportive of dendrite regeneration

  15. Roles for mitotic history in the generation and degeneration of hippocampal neuroarchitecture.

    Science.gov (United States)

    Mattson, M P; Guthrie, P B; Hayes, B C; Kater, S B

    1989-04-01

    The mechanisms regulating the highly ordered neuroarchitecture of the mammalian brain are largely unknown. The present study took advantage of hippocampal pyramidal-like neurons that arose from a common progenitor cell in cell culture (sister neurons) to ascertain the contribution of intrinsic factors to both the generation and degeneration of neuroarchitecture. Sister neurons were similar in overall cell form and dendritic numbers and lengths. Control non-sister neurons that grew in contact did not generate similar morphologies, indicating that the similarity of sister cells did not result from influences of the local microenvironment or cell interactions. These results suggest that intrinsic factors related to mitotic history play a role in the generation of neuroarchitecture. Since particular groups of hippocampal neurons are sensitive to glutamate neurotoxicity in situ and are vulnerable in neurodegenerative disorders, it was of interest to test glutamate sensitivity in the neuronal population and in mitotic sister neurons. A subpopulation of pyramidal neurons was sensitive to glutamate neurotoxicity. A striking finding was that sister neurons were invariably either both sensitive or both resistant to glutamate, while non-sister neurons often showed different responses to glutamate. Pharmacological studies indicated that glutamate neurotoxicity was mediated by kainate/quisqualate type receptors by a mechanism involving calcium influx through membrane channels. Fura-2 measurements of intracellular calcium revealed that sister neurons had similar rest levels of calcium and, strikingly, glutamate caused a dramatic increase in intracellular calcium levels only in neurons which subsequently degenerated. Apparently, intrinsic differences in sensitivity to glutamate lie at a point prior to calcium entry, probably at the level of glutamate receptors. Taken together, these results indicate that the mitotic history of a neuron can determine its presence and potential for

  16. Pyramid Lake Task Force : Final report

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The Pyramid Lake Task Force was created to address Pyramid Lake’s recession and recommend possible solutions that would consider both the needs for preserving the...

  17. One Kind of Network Complexity Pyramid

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>Pyramid architecture can be widely found in nature and most social fields. For example, Zoltvai and Barabasi firstly proposed the life’s complexity pyramid in biology science, and it was found that the

  18. A Rebuttal of NTL Institute's Learning Pyramid

    Science.gov (United States)

    Letrud, Kare

    2012-01-01

    This article discusses the learning pyramid corroborated by National Training Laboratories Institute. It present and compliment historical and methodological critique against the learning pyramid, and call upon NTL Institute ought to retract their model.

  19. Zbtb20-Induced CA1 Pyramidal Neuron Development and Area Enlargement in the Cerebral Midline Cortex of Mice

    DEFF Research Database (Denmark)

    Nielsen, Jakob V; Blom, Jonas B; Noraberg, Jens

    2010-01-01

    Expression of the transcriptional repressor Zbtb20 is confined to the hippocampal primordium of the developing dorsal midline cortex in mice. Here, we show that misexpression of Zbtb20 converts projection neurons of the subiculum and postsubiculum (dorsal presubiculum) to CA1 pyramidal neurons...... that are innervated by Schaffer collateral projections in ectopic strata oriens and radiatum. The Zbtb20-transformed neurons express Bcl11B, Satb2, and Calbindin-D28k, which are markers of adult CA1 pyramidal neurons. Downregulation of Zbtb20 expression by RNA interference impairs the normal maturation of CA1...... pyramidal neurons resulting in deficiencies in Calbindin-D28k expression and in reduced apical dendritic arborizations in stratum lacunosum moleculare. Overall, the results show that Zbtb20 is required for various aspects of CA1 pyramidal neuron development such as the postnatal extension of apical...

  20. GABAB and adenosine receptors mediate enhancement of the K+ current, IAHP, by reducing adenylyl cyclase activity in rat CA3 hippocampal neurons.

    Science.gov (United States)

    Gerber, U; Gähwiler, B H

    1994-11-01

    1. Gamma-aminobuturic acid-B (GABAB) and adenosine A1 receptors, which are expressed in hippocampal pyramidal cells, are linked to pertussis toxin-sensitive G-proteins known to be coupled negatively to the enzyme adenylyl cyclase. This study investigates the electrophysiological consequences of adenylyl cyclase inhibition in response to stimulation of these receptors. 2. Single-electrode voltage-clamp recordings were obtained from CA3 pyramidal cells in rat hippocampal slice cultures in presence of tetrodotoxin. The calcium-dependent potassium current (IAHP), which is very sensitive to intracellular levels of adenosine 3',5'-cyclic monophosphate (cAMP), was used as an electrophysiological indicator of adenylyl cyclase activity. 3. Application of baclofen (10 microM), a selective agonist at GABAB receptors, or adenosine (50 microM) each resulted in a transient decrease followed by a significant enhancement in the amplitude of evoked IAHP. The initial reduction in amplitude of IAHP probably reflects inadequacies in voltage clamp of electronically distant dendritic sites, due to the shunting caused by concomitant activation of potassium conductance by baclofen/adenosine. Comparable increases in membrane conductance in response to the GABAA agonist, muscimol, caused a similar reduction in IAHP. The enhancement of IAHP is consistent with an inhibition of constitutively active adenylyl cyclase. 4. The receptor mediating the responses to adenosine was identified as belonging to the A1 subtype on the basis of its sensitivity to the selective antagonist 8-cyclopentyl-1,3-dipropylxanthine.(ABSTRACT TRUNCATED AT 250 WORDS)

  1. Urban Public Health: Is There a Pyramid?

    OpenAIRE

    Meirong Su; Bin Chen; Zhifeng Yang; Yanpeng Cai; Jiao Wang

    2013-01-01

    Early ecologists identified a pyramidal trophic structure in terms of number, biomass and energy transfer. In 1943, the psychologist Maslow put forward a pyramid model to describe layers of human needs. It is indicated that the pyramid principle is universally applicable in natural, humanistic and social disciplines. Here, we report that a pyramid structure also exists in urban public health (UPH). Based on 18 indicators, the UPH states of four cities (Beijing, Tokyo, New York, and London) ar...

  2. A magic pyramid of supergravities

    Energy Technology Data Exchange (ETDEWEB)

    Anastasiou, A.; Borsten, L.; Duff, M.J.; Hughes, L.J.; Nagy, S. [Theoretical Physics, Blackett Laboratory, Imperial College London,London SW7 2AZ (United Kingdom)

    2014-04-29

    By formulating N=1,2,4,8, D=3, Yang-Mills with a single Lagrangian and single set of transformation rules, but with fields valued respectively in ℝ,ℂ,ℍ,O, it was recently shown that tensoring left and right multiplets yields a Freudenthal-Rosenfeld-Tits magic square of D=3 supergravities. This was subsequently tied in with the more familiar ℝ,ℂ,ℍ,O description of spacetime to give a unified division-algebraic description of extended super Yang-Mills in D=3,4,6,10. Here, these constructions are brought together resulting in a magic pyramid of supergravities. The base of the pyramid in D=3 is the known 4×4 magic square, while the higher levels are comprised of a 3×3 square in D=4, a 2×2 square in D=6 and Type II supergravity at the apex in D=10. The corresponding U-duality groups are given by a new algebraic structure, the magic pyramid formula, which may be regarded as being defined over three division algebras, one for spacetime and each of the left/right Yang-Mills multiplets. We also construct a conformal magic pyramid by tensoring conformal supermultiplets in D=3,4,6. The missing entry in D=10 is suggestive of an exotic theory with G/H duality structure F{sub 4(4)}/Sp(3)×Sp(1)

  3. A magic pyramid of supergravities

    Science.gov (United States)

    Anastasiou, A.; Borsten, L.; Duff, M. J.; Hughes, L. J.; Nagy, S.

    2014-04-01

    By formulating = 1, 2, 4, 8, D = 3, Yang-Mills with a single Lagrangian and single set of transformation rules, but with fields valued respectively in , it was recently shown that tensoring left and right multiplets yields a Freudenthal-Rosenfeld-Tits magic square of D = 3 supergravities. This was subsequently tied in with the more familiar description of spacetime to give a unified division-algebraic description of extended super Yang-Mills in D = 3, 4, 6, 10. Here, these constructions are brought together resulting in a magic pyramid of supergravities. The base of the pyramid in D = 3 is the known 4 × 4 magic square, while the higher levels are comprised of a 3 × 3 square in D = 4, a 2 × 2 square in D = 6 and Type II supergravity at the apex in D = 10. The corresponding U-duality groups are given by a new algebraic structure, the magic pyramid formula, which may be regarded as being defined over three division algebras, one for spacetime and each of the left/right Yang-Mills multiplets. We also construct a conformal magic pyramid by tensoring conformal supermultiplets in D = 3, 4, 6. The missing entry in D = 10 is suggestive of anexotic theory with G/ H duality structure F 4(4)/Sp(3) × Sp(1).

  4. The Base of the Pyramid

    NARCIS (Netherlands)

    Hutte, E.; Vermeulen, P.A.M.

    2014-01-01

    This chapter provides a brief background to the Base of the Pyramid (BoP) phenomenon. It begins with a discussion on what sets the BoP markets apart from more traditional markets and why companies have not identified them as a business opportunity. The chapter then provides an overview of how

  5. Three Types of Network Complexity Pyramid

    Institute of Scientific and Technical Information of China (English)

    FANG; Jin-qing; LI; Yong; LIU; Qiang

    2012-01-01

    <正>Exploring the complexity and diversity of complex networks have been very challenging issues in network science and engineering. Among them exploring the network complexity pyramids (NCP) are one of important expressions in network complexity. So far as we have proposed the three types of the network complexity pyramid (NCP). The first type of NCP is the network model complexity pyramid with

  6. The Chinese Pyramids and the Sun

    CERN Document Server

    Sparavigna, Amelia Carolina

    2012-01-01

    The Chinese Pyramids are huge ancient burial mounds. In the satellite images we can see some complexes where the main buildings are the pyramidal mounds of an emperor and his empress. Here we discuss a possible sunrise/sunset orientation of these two pyramids on the solstices and equinoxes.

  7. Role of Cl(-) -HCO3(-) exchanger AE3 in intracellular pH homeostasis in cultured murine hippocampal neurons, and in crosstalk to adjacent astrocytes.

    Science.gov (United States)

    Salameh, Ahlam I; Hübner, Christian A; Boron, Walter F

    2017-01-01

    A polymorphism of human AE3 is associated with idiopathic generalized epilepsy. Knockout of AE3 in mice lowers the threshold for triggering epileptic seizures. The explanations for these effects are elusive. Comparisons of cells from wild-type vs. AE3(-/-) mice show that AE3 (present in hippocampal neurons, not astrocytes; mediates HCO3(-) efflux) enhances intracellular pH (pHi ) recovery (decrease) from alkali loads in neurons and, surprisingly, adjacent astrocytes. During metabolic acidosis (MAc), AE3 speeds initial acidification, but limits the extent of pHi decrease in neurons and astrocytes. AE3 speeds re-alkalization after removal of MAc in neurons and astrocytes, and speeds neuronal pHi recovery from an ammonium prepulse-induced acid load. We propose that neuronal AE3 indirectly increases acid extrusion in (a) neurons via Cl(-) loading, and (b) astrocytes by somehow enhancing NBCe1 (major acid extruder). The latter would enhance depolarization-induced alkalinization of astrocytes, and extracellular acidification, and thereby reduce susceptibility to epileptic seizures. The anion exchanger AE3, expressed in hippocampal (HC) neurons but not astrocytes, contributes to intracellular pH (pHi ) regulation by facilitating the exchange of extracellular Cl(-) for intracellular HCO3(-) . The human AE3 polymorphism A867D is associated with idiopathic generalized epilepsy. Moreover, AE3 knockout (AE3(-/-) ) mice are more susceptible to epileptic seizure. The mechanism of these effects has been unclear because the starting pHi in AE3(-/-) and wild-type neurons is indistinguishable. The purpose of the present study was to use AE3(-/-) mice to investigate the role of AE3 in pHi homeostasis in HC neurons, co-cultured with astrocytes. We find that the presence of AE3 increases the acidification rate constant during pHi recovery from intracellular alkaline loads imposed by reducing [CO2 ]. The presence of AE3 also speeds intracellular acidification during the early phase of

  8. The FINUT healthy lifestyles guide: Beyond the food pyramid.

    Science.gov (United States)

    Gil, Angel; Ruiz-Lopez, Maria Dolores; Fernandez-Gonzalez, Miguel; Martinez de Victoria, Emilio

    2014-05-01

    The WHO has proposed that health be promoted and protected through the development of an environment that enables sustainable actions at individual, community, national, and global levels. Indeed, food-based dietary guidelines, i.e., food pyramids, have been developed in numerous countries to disseminate nutritional information to the general population. However, wider recommendations are needed, with information on an active healthy lifestyle, not just healthy eating. The objective of the present work is to propose a three-dimensional pyramid as a new strategy for promoting adequate nutrition and active healthy lifestyles in a sustainable way. Indeed, the Iberoamerican Nutrition Foundation (FINUT) pyramid of healthy lifestyles has been designed as a tetrahedron, with its 3 lateral faces corresponding to the facets of food and nutrition, physical activity and rest, and education and hygiene. Each lateral face is divided into 2 triangles. These faces show the following: 1) food-based guidelines and healthy eating habits as related to a sustainable environment; 2) recommendations for rest and physical activity and educational, social, and cultural issues; and 3) selected hygiene and educational guidelines that, in conjunction with the other 2 faces, would contribute to better health for people in a sustainable planet. The new FINUT pyramid is addressed to the general population of all ages and should serve as a guide for living a healthy lifestyle within a defined social and cultural context. It includes an environmental and sustainability dimension providing measures that should contribute to the prevention of noncommunicable chronic diseases.

  9. [The finut healthy lifestyles guide: beyond the food pyramid].

    Science.gov (United States)

    Gil, Angel; Ruiz-Lopez, Maria Dolores; Fernandez-Gonzalez, Miguel; Martinez de Victoria, Emilio

    2015-05-01

    The World Health Organization has proposed that health be promoted and protected through the development of an environment that enables sustainable actions at individual, community, national and global levels. Indeed, food-based dietary guidelines, i.e., food pyramids, have been developed in numerous countries to disseminate nutritional information to the general population. However, wider recommendations are needed, with information on an active, healthy lifestyle, not just healthy eating. The objective of the present work is to propose a three-dimensional pyramid as a new strategy for promoting adequate nutrition and active healthy lifestyles in a sustainable way. Indeed, the Iberomerican Nutrition Foundation (FINUT) pyramid of healthy lifestyles has been designed as a tetrahedron, its three lateral faces corresponding to the binomials food and nutrition, physical activity and rest, and education and hygiene. Each lateral face is divided into two triangles. These faces show the following: 1. food-based guidelines and healthy eating habits as related to a sustainable environment; 2. recommendations for rest and physical activity and educational, social and cultural issues; 3. selected hygiene and educational guidelines that, in conjunction with the other two faces, would contribute to better health and provide measures to promote environmental sustainability. The new FINUT pyramid is addressed to the general population of all ages and should serve as a guide for living a healthy lifestyle within a defined social and cultural context. It includes an environmental and sustainability dimension providing measures that should contribute to the prevention of non-communicable chronic diseases.

  10. Differential NMDA receptor-dependent calcium loading and mitochondrial dysfunction in CA1 vs. CA3 hippocampal neurons.

    Science.gov (United States)

    Stanika, Ruslan I; Winters, Christine A; Pivovarova, Natalia B; Andrews, S Brian

    2010-02-01

    Hippocampal CA1 pyramidal neurons are selectively vulnerable to ischemia, while adjacent CA3 neurons are relatively resistant. Although glutamate receptor-mediated mitochondrial Ca(2+) overload and dysfunction is a major component of ischemia-induced neuronal death, no direct relationship between selective neuronal vulnerability and mitochondrial dysfunction has been demonstrated in intact brain preparations. Here, we show that in organotypic slice cultures NMDA induces much larger Ca(2+) elevations in vulnerable CA1 neurons than in resistant CA3. Consequently, CA1 mitochondria exhibit stronger calcium accumulation, more extensive swelling and damage, stronger depolarization of their membrane potential, and a significant increase in ROS generation. NMDA-induced Ca(2+) and ROS elevations were abolished in Ca(2+)-free medium or by NMDAR antagonists, but not by zinc chelation. We conclude that Ca(2)(+) overload-dependent mitochondrial dysfunction is a determining factor in the selective vulnerability of CA1 neurons.

  11. Expression and changes of hyperoxidized peroxiredoxins in non-pyramidal and polymorphic cells in the gerbil hippocampus during normal aging.

    Science.gov (United States)

    Yoo, Ki-Yeon; Park, Ok Kyu; Yu, Jiatian; Yan, Bingchun; Li, Hua; Lee, Choong Hyun; Choi, Jung Hoon; Kim, Dae Won; Hwang, In Koo; Won, Moo-Ho

    2009-05-01

    Oxidative stress is one of predisposing factors to age-related neurodegeneration in the brain. In particular, thiol-containing groups are susceptible to oxidative stress, which induces the formation of the disulfide bond and/or hyperoxidized form of thiol-containing proteins. We observed the protein thiol levels in the hippocampal homogenates and also investigated changes in hyperoxidized form of peroxiredoxin (Prx-SO(3)) immunoreactivity and proteins levels in the gerbil hippocampal subregions during normal aging. Levels of total thiol, non-protein thiol, and protein thiol were decreased in the hippocampal homogenates with age. At post-natal month 1 (PM 1), pyramidal and non-pyramidal cells in the hippocampal CA1 region (CA1) showed Prx-SO(3) immunoreactivity. Prx-SO(3) immunoreactivity in the cells was decreased by PM 12, thereafter, Prx-SO(3) immunoreactivity in the cells increased again with age. In the CA2/3, Prx-SO(3) immunoreactivity in pyramidal cells was not significantly changed; however, the immunoreactivity in pyramidal cells was very low at PM 12. Prx-SO(3) immunoreactivity in the dentate gyrus (DG) was distinctly changed during aging. At PM 1, Prx-SO(3) immunoreactivity in granule and polymorphic cells was weak and strong, respectively. The immunoreactivity in the neurons was decreased with age, not shown in any neurons at PM 12. Thereafter, Prx-SO(3) immunoreactivity increased again with age. In addition, Prx-SO(3) protein level in the hippocampus was lowest at PM 12. These results suggest that thiol-containing proteins are changed during aging and Prx-SO(3) immunoreactivity was different according to cells in the hippocampal subregion during aging.

  12. HIV-1 Tat activates indoleamine 2,3 dioxygenase in murine organotypic hippocampal slice cultures in a p38 mitogen-activated protein kinase-dependent manner

    Directory of Open Access Journals (Sweden)

    Kelley Keith W

    2011-08-01

    Full Text Available Abstract Background We have established that activation of the tryptophan degrading enzyme indoleamine 2,3 dioxygenase (IDO mediates the switch from cytokine-induced sickness behavior to depressive-like behavior. Because human immunodeficiency virus type 1 (HIV-1 Tat protein causes depressive-like behavior in mice, we investigated its ability to activate IDO in organotypic hippocampal slice cultures (OHSCs derived from neonatal C57BL/6 mice. Methods Depressive-like behavior in C57BL/6J mice was assessed by the forced swim test. Expression of cytokines and IDO mRNA in OHSCs was measured by real-time RT-PCR and cytokine protein was measured by enzyme-linked immunosorbent assays (ELISAs. p38 MAPK phosphorylation was analyzed by western blot. Results Intracerebroventricular (i.c.v. administration of Tat (40 ng induced depressive-like behavior in the absence of sickness. Addition of Tat (40 ng/slice to the medium of OHSCs induced IDO steady-state mRNA that peaked at 6 h. This effect was potentiated by pretreatment with IFNγ. Tat also induced the synthesis and release of TNFα and IL-6 protein in the supernatant of the slices and increased expression of the inducible isoform of nitric oxide synthase (iNOS and the serotonin transporter (SERT. Tat had no effect on endogenous synthesis of IFNγ. To explore the mechanisms of Tat-induced IDO expression, slices were pretreated with the p38 mitogen-activated protein kinase (MAPK inhibitor SB 202190 for 30 min before Tat treatment. SB 202190 significantly decreased IDO expression induced by Tat, and this effect was accompanied by a reduction of Tat-induced expression of TNFα, IL-6, iNOS and SERT. Conclusion These data establish that Tat induces IDO expression via an IFNγ-independent mechanism that depends upon activation of p38 MAPK. Targeting IDO itself or the p38 MAPK signaling pathway could provide a novel therapy for comorbid depressive disorders in HIV-1-infected patients.

  13. Central Administration of Lipopolysaccharide Induces Depressive-like Behavior in Vivo and Activates Brain Indoleamine 2,3 Dioxygenase In Murine Organotypic Hippocampal Slice Cultures

    Directory of Open Access Journals (Sweden)

    Kavelaars Annemieke

    2010-08-01

    Full Text Available Abstract Background Transient stimulation of the innate immune system by an intraperitoneal injection of lipopolysaccharide (LPS activates peripheral and central expression of the tryptophan degrading enzyme indoleamine 2,3 dioxygenase (IDO which mediates depressive-like behavior. It is unknown whether direct activation of the brain with LPS is sufficient to activate IDO and induce depressive-like behavior. Methods Sickness and depressive-like behavior in C57BL/6J mice were assessed by social exploration and the forced swim test, respectively. Expression of cytokines and IDO mRNA was measured by real-time RT-PCR and cytokine protein was measured by enzyme-linked immunosorbent assays (ELISAs. Enzymatic activity of IDO was estimated as the amount of kynurenine produced from tryptophan as determined by high pressure liquid chromatography (HPLC with electrochemical detection. Results Intracerebroventricular (i.c.v. administration of LPS (100 ng increased steady-state transcripts of TNFα, IL-6 and the inducible isoform of nitric oxide synthase (iNOS in the hippocampus in the absence of any change in IFNγ mRNA. LPS also increased IDO expression and induced depressive-like behavior, as measured by increased duration of immobility in the forced swim test. The regulation of IDO expression was investigated using in situ organotypic hippocampal slice cultures (OHSCs derived from brains of newborn C57BL/6J mice. In accordance with the in vivo data, addition of LPS (10 ng/ml to the medium of OHSCs induced steady-state expression of mRNA transcripts for IDO that peaked at 6 h and translated into increased IDO enzymatic activity within 8 h post-LPS. This activation of IDO by direct application of LPS was preceded by synthesis and secretion of TNFα and IL-6 protein and activation of iNOS while IFNγ expression was undetectable. Conclusion These data establish that activation of the innate immune system in the brain is sufficient to activate IDO and induce

  14. The Digital Von Fahrenheid Pyramid

    Science.gov (United States)

    Bura, M.; Janowski, J.; Wężyk, P.; Zięba, K.

    2017-08-01

    3D Scanners Lab from Digital Humanities Laboratory at the University of Warsaw initiated the scientific project, the purpose of which was to call attention to systematically penetrated and devastated pyramid-shaped tomb from the XVIII/XIX century, of family von Fahrenheid in Rapa in Banie Mazurskie commune (NE Poland). By conducting a series of non-invasive studies, such as 3D inventory using terrestrial laser scanning (TLS), thermal imaging, georadar measurements (around and inside the tomb) and anthropological research of mummified remains as well - the complete dataset was collected. Through the integration of terrestrial (TLS) and airborne laser scanning (ALS) authors managed to analyse the surroundings of Fahrenheid pyriamid and influence of some objects (like trees) on the condition and visibility of the Pyramids in the landscape.

  15. Pretrial Hippocampal ?-State Differentiates Single-Unit Response Profiles during Rabbit Trace Eyeblink Conditioning

    Science.gov (United States)

    Cicchese, Joseph J.; Darling, Ryan D.; Berry, Stephen D.

    2015-01-01

    Eyeblink conditioning given in the explicit presence of hippocampal ? results in accelerated learning and enhanced multiple-unit responses, with slower learning and suppression of unit activity under non-? conditions. Recordings from putative pyramidal cells during ?-contingent training show that pretrial ?-state is linked to the probability of…

  16. Uncovering representations of sleep-associated hippocampal ensemble spike activity

    Science.gov (United States)

    Chen, Zhe; Grosmark, Andres D.; Penagos, Hector; Wilson, Matthew A.

    2016-08-01

    Pyramidal neurons in the rodent hippocampus exhibit spatial tuning during spatial navigation, and they are reactivated in specific temporal order during sharp-wave ripples observed in quiet wakefulness or slow wave sleep. However, analyzing representations of sleep-associated hippocampal ensemble spike activity remains a great challenge. In contrast to wake, during sleep there is a complete absence of animal behavior, and the ensemble spike activity is sparse (low occurrence) and fragmental in time. To examine important issues encountered in sleep data analysis, we constructed synthetic sleep-like hippocampal spike data (short epochs, sparse and sporadic firing, compressed timescale) for detailed investigations. Based upon two Bayesian population-decoding methods (one receptive field-based, and the other not), we systematically investigated their representation power and detection reliability. Notably, the receptive-field-free decoding method was found to be well-tuned for hippocampal ensemble spike data in slow wave sleep (SWS), even in the absence of prior behavioral measure or ground truth. Our results showed that in addition to the sample length, bin size, and firing rate, number of active hippocampal pyramidal neurons are critical for reliable representation of the space as well as for detection of spatiotemporal reactivated patterns in SWS or quiet wakefulness.

  17. A magic pyramid of supergravities

    CERN Document Server

    Anastasiou, A; Duff, M J; Hughes, L J; Nagy, S

    2013-01-01

    By formulating N = 1, 2, 4, 8, D = 3, Yang-Mills with a single Lagrangian and single set of transformation rules, but with fields valued respectively in R,C,H,O, it was recently shown that tensoring left and right multiplets yields a Freudenthal-Rosenfeld-Tits magic square of D = 3 supergravities. This was subsequently tied in with the more familiar R,C,H,O description of spacetime to give a unified division-algebraic description of extended super Yang-Mills in D = 3, 4, 6, 10. Here, these constructions are brought together resulting in a magic pyramid of supergravities. The base of the pyramid in D = 3 is the known 4x4 magic square, while the higher levels are comprised of a 3x3 square in D = 4, a 2x2 square in D = 6 and Type II supergravity at the apex in D = 10. The corresponding U-duality groups are given by a new algebraic structure, the magic pyramid formula, which may be regarded as being defined over three division algebras, one for spacetime and each of the left/right Yang-Mills multiplets. We also c...

  18. NMDA Receptors Regulate the Structural Plasticity of Spines and Axonal Boutons in Hippocampal Interneurons

    Directory of Open Access Journals (Sweden)

    Marta Perez-Rando

    2017-06-01

    Full Text Available N-methyl-D-aspartate receptors (NMDARs are present in both pyramidal neurons and interneurons of the hippocampus. These receptors play an important role in the adult structural plasticity of excitatory neurons, but their impact on the remodeling of interneurons is unknown. Among hippocampal interneurons, somatostatin-expressing cells located in the stratum oriens are of special interest because of their functional importance and structural characteristics: they display dendritic spines, which change density in response to different stimuli. In order to understand the role of NMDARs on the structural plasticity of these interneurons, we have injected acutely MK-801, an NMDAR antagonist, to adult mice which constitutively express enhanced green fluorescent protein (EGFP in these cells. We have behaviorally tested the animals, confirming effects of the drug on locomotion and anxiety-related behaviors. NMDARs were expressed in the somata and dendritic spines of somatostatin-expressing interneurons. Twenty-four hours after the injection, the density of spines did not vary, but we found a significant increase in the density of their en passant boutons (EPB. We have also used entorhino-hippocampal organotypic cultures to study these interneurons in real-time. There was a rapid decrease in the apparition rate of spines after MK-801 administration, which persisted for 24 h and returned to basal levels afterwards. A similar reversible decrease was detected in spine density. Our results show that both spines and axons of interneurons can undergo remodeling and highlight NMDARs as regulators of this plasticity. These results are specially relevant given the importance of all these players on hippocampal physiology and the etiopathology of certain psychiatric disorders.

  19. Histaminergic system in co-cultures of hippocampus and posterior hypothalamus: a morphological and electrophysiological study in the rat.

    Science.gov (United States)

    Diewald, L; Heimrich, B; Büsselberg, D; Watanabe, T; Haas, H L

    1997-11-01

    Neurons of the tuberomammillary nucleus in the posterior hypothalamus diffusely project to most parts of the central nervous system, where their main transmitter, histamine, modulates the excitability of the target neurons. The development of a histaminergic hypothalamo-hippocampal pathway and its function were studied in organotypic co-cultures. Immunocytochemistry for histidine decarboxylase, the specific synthesizing enzyme, stained clusters of neurons in the hypothalamic tuberomammillary area. Immunolabelled varicose processes innervated the co-cultured hippocampus and established a few synaptic contacts on dendrites. Cultured tuberomammillary neurons displayed their typical membrane properties and were spontaneously active. In hippocampal pyramidal cells of the CA3 region the long-lasting afterhyperpolarization was reduced by histamine or impromidine and increased by the H2 antagonist cimetidine, but not by the H1 antagonist mepyramine. The membrane potential was depolarized in presence of an H2 agonist and hyperpolarized by an H2 antagonist. In single hippocampal cultures histamine antagonists did not affect afterhyperpolarization and membrane potential. Histaminergic neurons retain their main morphological and physiological characteristics in slice cultures and establish a functional connection with co-cultured target cells.

  20. 磷酸吡哆醛对培养的海马神经细胞形态学的影响%The effects of pyridoxal phosphate on morphological changes in cultured hippocampal neurons

    Institute of Scientific and Technical Information of China (English)

    耿美玉; 李静; 辛现良; 邓岗; 徐家敏; 管华诗

    2000-01-01

    The effects of pyridoxal phosphate (PLP) on the morphological changes of cultured hippocampal neurons celle were investigated. Hippocampal neurons from an 18 day old embryonic Wistar rat were prepared by enzymatic digestion and exposed to PLP in the low cell density condition. The results indicate that PLP at concentrations of 1, 10μm significantly promoted the elongation of the longest axon-like process in low cell density cultures. On the other hand, PLP showed no effects on other parameters such as the total length of dendrites, the numbe rs of branch points per axon, and the numbers of processes per soma. Ifenprodil and picrotoxin, although at the concentrations both counteracted the survival-promo ting activities of hippocampal neurons caused by PLP, failed to take any actions on the neurite elongation induced by PLP. In conclusion, PLP did have the elong ation-promoting activity for hippocampal neurons, the mechanisms underlying its positive effects on neurogenesis needs to be further elucidated.%实验观察磷酸吡哆醛对培养的海马神经细胞形态学的影响,选用妊娠18d Wistar大鼠胎鼠,采用酶消化法获得单个海马神经细胞,通过原代低密度细胞培养法观察磷酸吡哆醛 (PLP)对其形态学的影响.结果表明:在浓度为1,10μ m时,能明显地促进海马神经细胞轴突的伸展,但对树突总长度、每个轴突上的分叉数及胞体的突起数均无明显影响;Ifen prodil和Picrotoxin尽管能明显拮抗PLP介导的神经细胞营养作用,但对PLP的促神经细胞伸展作用却无明显影响.总之,认为PLP致所以具有促海马神经细胞轴突伸展作用,不是由于P LP介导的神经细胞的营养增加,其详细机理有待于进一步探讨.

  1. Effects of serotonin in the hippocampus: how SSRIs and multimodal antidepressants might regulate pyramidal cell function.

    Science.gov (United States)

    Dale, Elena; Pehrson, Alan L; Jeyarajah, Theepica; Li, Yan; Leiser, Steven C; Smagin, Gennady; Olsen, Christina K; Sanchez, Connie

    2016-04-01

    The hippocampus plays an important role in emotional and cognitive processing, and both of these domains are affected in patients with major depressive disorder (MDD). Extensive preclinical research and the notion that modulation of serotonin (5-HT) neurotransmission plays a key role in the therapeutic efficacy of selective serotonin reuptake inhibitors (SSRIs) support the view that 5-HT is important for hippocampal function in normal and disease-like conditions. The hippocampus is densely innervated by serotonergic fibers, and the majority of 5-HT receptor subtypes are expressed there. Furthermore, hippocampal cells often co-express multiple 5-HT receptor subtypes that can have either complementary or opposing effects on cell function, adding to the complexity of 5-HT neurotransmission. Here we review the current knowledge of how 5-HT, through its various receptor subtypes, modulates hippocampal output and the activity of hippocampal pyramidal cells in rodents. In addition, we discuss the relevance of 5-HT modulation for cognitive processing in rodents and possible clinical implications of these results in patients with MDD. Finally, we review the data on how SSRIs and vortioxetine, an antidepressant with multimodal activity, affect hippocampal function, including cognitive processing, from both a preclinical and clinical perspective.

  2. The pyramids of Greece: Ancient meridian observatories?

    Science.gov (United States)

    Theodossiou, Efstratios; Manimanis, Vassilios N.; Dimitrijević, Milan S.; Katsiotis, Marco

    Pyramids, "Dragon Houses" ("Drakospita") and megalithic structures in general create always a special interest. We postulate that, as happens with the Drakospita of Euboea, the pyramid-like structures of Argolis (Eastern Peloponnese) were constructed by the Dryops. It is known that, in addition to Euboea and some Cyclades islands, this prehellenic people had also settled in Argolis, where they founded the city of Asine. We also propose that the pyramids of Argolis and in particular the pyramid of Hellinikon village were very likely, besides being a burial monument or guard house, might be served also for astronomical observations.

  3. Zbtb20 Defines a Hippocampal Neuronal Identity Through Direct Repression of Genes That Control Projection Neuron Development in the Isocortex

    DEFF Research Database (Denmark)

    Nielsen, Jakob V; Thomassen, Mads; Møllgård, Kjeld

    2014-01-01

    Hippocampal pyramidal neurons are important for encoding and retrieval of spatial maps and episodic memories. While previous work has shown that Zbtb20 is a cell fate determinant for CA1 pyramidal neurons, the regulatory mechanisms governing this process are not known. In this study, we demonstrate...... that Zbtb20 binds to genes that control neuronal subtype specification in the developing isocortex, including Cux1, Cux2, Fezf2, Foxp2, Mef2c, Rorb, Satb2, Sox5, Tbr1, Tle4, and Zfpm2. We show that Zbtb20 represses these genes during ectopic CA1 pyramidal neuron development in transgenic mice. These data...

  4. Update on the Pyramid Scheme

    Science.gov (United States)

    Banks, Tom; Torres, T. J.

    2012-10-01

    We summarize recent work in which we attempt to make consistent models of LHC physics, from the Pyramid Scheme. The models share much with the NMSSM, in particular, enhanced tree level contributions to the Higgs mass and a preference for small tan β. There are three different singlet fields, and a new strongly coupled gauge theory, so the constraints of perturbative unification are quite different. We outline our general approach to the model, which contains a Kähler potential for three of the low energy fields, which is hard to calculate. Detailed calculations, based on approximations to the Kähler potential, will be presented in a future publication.

  5. Dynamic Expression Patterns of Progenitor and Pyramidal Neuron Layer Markers in the Developing Human Hippocampus.

    Science.gov (United States)

    Cipriani, Sara; Nardelli, Jeannette; Verney, Catherine; Delezoide, Anne-Lise; Guimiot, Fabien; Gressens, Pierre; Adle-Biassette, Homa

    2016-03-01

    The molecular mechanisms underlying the formation of hippocampus are unknown in humans. To improve our knowledge of molecules that potentially regulate pyramidal neurogenesis and layering in various hippocampal fields, we investigated the expression of progenitor markers and cell fate molecules from gestational week (GW) 9 to GW 20. At GW 9, the progenitor cell compartment of the hippocampal formation mainly consisted of PAX6(+) cells in the ventricular zone. Between GW 9 and 11, a second germinal area, the subventricular zone (SVZ), was formed, as shown by TBR2 labeling. Postmitotic markers (TBR1, CTIP2, SATB2, and CUX1) might reflect the inside-out layering of the plate from GW 11 onwards. TBR1(+) neurons appeared in the deep plate, whereas CTIP2(+), SATB2(+), and CUX1(+) neurons occupied the upper layers. From GW 16, differences in layer segregation were observed between the ammonic and subicular plates. Moreover, an ammonic-to-subicular maturation gradient was observed in germinal/postmitotic areas. Taken together, these findings demonstrate for the first time the presence of an SVZ in the hippocampus of human fetuses and laminar differences in transcription factor expression in the pyramidal layer of the human ammonic and subicular plate, and provide new information to further investigate the connectivity of the hippocampal formation.

  6. Hippocampal Neurogenesis and Ageing

    OpenAIRE

    Couillard-Després, Sébastien

    2012-01-01

    Although significant inconsistencies remain to be clarified, a role for neurogenesis in hippocampal functions, such as cognition, has been suggested by several reports. Yet, investigation in various species of mammals, including humans, revealed that rates of hippocampal neurogenesis are steadily declining with age. The very low levels of hippocampal neurogenesis persisting in the aged brain have been suspected to underlie the cognitive deficits observed in elderly. However, current evidence ...

  7. Profiles of hippocampal neuron activity during auditory discrimination cognition in guinea pigs

    Institute of Scientific and Technical Information of China (English)

    GAO Jie; LUO Jun; XIONG Ying; YANG Ce; WANG Yong-tang; SUI Jian-feng

    2007-01-01

    Objective: To clarify the firing characteristics of the hippocampal pyramidal cells and interneurons in the auditory discrimination cognition. Methods: Thirteen guinea pigs were studied by the paired (active cognition group, n=10) or unpaired (passive cognition group, n=3) training with 1 kHz (CS+)and 500 Hz tones (CS-) and the air puff (US) applied 250 ms after the CS+ onset. Results: In active group, 32 pyramidal cells showed exciting response to the CS+ tone, 16 cells inhibited response and 4 cells revealed no response to the high frequency tone and18 interneurons almost unchanged. In passive group, the pyramidal cells responded to the tone casually and 10 out of the 13 interneurons remained invariably. Conclusion: The result suggests that the pyramidal cells play a major role in coding auditory information by the networks, and the interneuons may modulate it via forward and feedback.

  8. Active browsing using similarity pyramids

    Science.gov (United States)

    Chen, Jau-Yuen; Bouman, Charles A.; Dalton, John C.

    1998-12-01

    In this paper, we describe a new approach to managing large image databases, which we call active browsing. Active browsing integrates relevance feedback into the browsing environment, so that users can modify the database's organization to suit the desired task. Our method is based on a similarity pyramid data structure, which hierarchically organizes the database, so that it can be efficiently browsed. At coarse levels, the similarity pyramid allows users to view the database as large clusters of similar images. Alternatively, users can 'zoom into' finer levels to view individual images. We discuss relevance feedback for the browsing process, and argue that it is fundamentally different from relevance feedback for more traditional search-by-query tasks. We propose two fundamental operations for active browsing: pruning and reorganization. Both of these operations depend on a user-defined relevance set, which represents the image or set of images desired by the user. We present statistical methods for accurately pruning the database, and we propose a new 'worm hole' distance metric for reorganizing the database, so that members of the relevance set are grouped together.

  9. Housing in Pyramid Counteracts Neuroendocrine and Oxidative Stress Caused by Chronic Restraint in Rats

    Directory of Open Access Journals (Sweden)

    M. Surekha Bhat

    2007-01-01

    Full Text Available The space within the great pyramid and its smaller replicas is believed to have an antistress effect. Research has shown that the energy field within the pyramid can protect the hippocampal neurons of mice from stress-induced atrophy and also reduce neuroendocrine stress, oxidative stress and increase antioxidant defence in rats. In this study, we have, for the first time, attempted to study the antistress effects of pyramid exposure on the status of cortisol level, oxidative damage and antioxidant status in rats during chronic restraint stress. Adult female Wistar rats were divided into four groups as follows: normal controls (NC housed in home cage and left in the laboratory; restrained rats (with three subgroups subject to chronic restraint stress by placing in a wire mesh restrainer for 6 h per day for 14 days, the restrained controls (RC having their restrainers kept in the laboratory; restrained pyramid rats (RP being kept in the pyramid; and restrained square box rats (RS in the square box during the period of restraint stress everyday. Erythrocyte malondialdehyde (MDA and plasma cortisol levels were significantly increased and erythrocyte-reduced glutathione (GSH levels, erythrocyte glutathione peroxidase (GSH-Px and superoxide dismutase (SOD activities were significantly decreased in RC and RS rats as compared to NC. However, these parameters were maintained to near normal levels in RP rats which showed significantly decreased erythrocyte MDA and plasma cortisol and significantly increased erythrocyte GSH levels, erythrocyte GSH-Px and SOD activities when compared with RS rats. The results showed that housing in pyramid counteracts neuroendocrine and oxidative stress caused by chronic restraint in rats.

  10. Three axonal projection routes of individual pyramidal cells in the ventral CA1 hippocampus

    Science.gov (United States)

    Arszovszki, Antónia; Borhegyi, Zsolt; Klausberger, Thomas

    2014-01-01

    Pyramidal cells of the ventral hippocampal CA1 area have numerous and diverse distant projections to other brain regions including the temporal and parietal association areas, visual, auditory, olfactory, somatosensory, gustatory, and visceral areas, and inputs to the amygdalar and prefrontal-orbital-agranular insular region. In addition, their differential expression of proteins like calbindin provides further indications for cellular diversity. This raises the possibility that the pyramidal cells may form subpopulations participating in different brain circuitries. To address this hypothesis we applied the juxtacellular labeling technique to fill individual pyramidal cells in the ventral hippocampus with neurobiotin in urethane anesthetized rats. For each labeled pyramidal cell we determined soma location, dendritic arborizations and selective expression of calbindin and norbin. Reconstruction and mapping of long-range axonal projections were made with the Neurolucida system. We found three major routes of ventral CA1 pyramidal cell projections. The classical pathway run caudo-ventrally across and innervating the subiculum, further to the parahippocampal regions and then to the deep and superficial layers of entorhinal cortex. The other two pathways avoided subiculum by branching from the main axon close to the soma and either traveled antero- and caudo-ventrally to amygdaloid complex, amygdalopiriform-transition area and parahippocampal regions or run antero-dorsally through the fimbria-fornix to the septum, hypothalamus, ventral striatum and olfactory regions. We found that most pyramidal cells investigated used all three major routes to send projecting axons to other brain areas. Our results suggest that the information flow through the ventral hippocampus is distributed by wide axonal projections from the CA1 area. PMID:25009471

  11. Housing in pyramid counteracts neuroendocrine and oxidative stress caused by chronic restraint in rats.

    Science.gov (United States)

    Bhat, M Surekha; Rao, Guruprasad; Murthy, K Dilip; Bhat, P Gopalakrishna

    2007-03-01

    The space within the great pyramid and its smaller replicas is believed to have an antistress effect. Research has shown that the energy field within the pyramid can protect the hippocampal neurons of mice from stress-induced atrophy and also reduce neuroendocrine stress, oxidative stress and increase antioxidant defence in rats. In this study, we have, for the first time, attempted to study the antistress effects of pyramid exposure on the status of cortisol level, oxidative damage and antioxidant status in rats during chronic restraint stress. Adult female Wistar rats were divided into four groups as follows: normal controls (NC) housed in home cage and left in the laboratory; restrained rats (with three subgroups) subject to chronic restraint stress by placing in a wire mesh restrainer for 6 h per day for 14 days, the restrained controls (RC) having their restrainers kept in the laboratory; restrained pyramid rats (RP) being kept in the pyramid; and restrained square box rats (RS) in the square box during the period of restraint stress everyday. Erythrocyte malondialdehyde (MDA) and plasma cortisol levels were significantly increased and erythrocyte-reduced glutathione (GSH) levels, erythrocyte glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) activities were significantly decreased in RC and RS rats as compared to NC. However, these parameters were maintained to near normal levels in RP rats which showed significantly decreased erythrocyte MDA and plasma cortisol and significantly increased erythrocyte GSH levels, erythrocyte GSH-Px and SOD activities when compared with RS rats. The results showed that housing in pyramid counteracts neuroendocrine and oxidative stress caused by chronic restraint in rats.

  12. The cradle of pyramids in satellite images

    CERN Document Server

    Sparavigna, Amelia Carolina

    2011-01-01

    We propose the use of image processing to enhance the Google Maps of some archaeological areas of Egypt. In particular we analyse that place which is considered the cradle of pyramids, where it was announced the discovery of a new pyramid by means of an infrared remote sensing.

  13. High temperatures alter physiological properties of pyramidal cells and inhibitory interneurons in hippocampus

    Directory of Open Access Journals (Sweden)

    Jennifer eKim

    2012-07-01

    Full Text Available Temperature has multiple effects on neurons, yet little is known about the effects of high temperature on the physiology of mammalian central neurons. Hyperthermia can influence behavior and cause febrile seizures. We studied the effects of acute hyperthermia on the immature hippocampus in vitro by recording from pyramidal neurons and inhibitory oriens-lacunosum moleculare (O-LM interneurons (identified by green fluorescent protein expression in the GIN mouse line. Warming to 41°C caused depolarization, spontaneous action potentials, reduced input resistance and membrane time constant, and increased spontaneous synaptic activity of most pyramidal cells and O-LM interneurons. Pyramidal neurons of area CA3 were more strongly excited by hyperthermia than those of area CA1. About 90% of O-LM interneurons in both CA1 and CA3 increased their firing rates at hyperthermic temperatures; interneurons in CA3 fired faster than those in CA1 on average. Blockade of fast synaptic transmission did not abolish the effect of hyperthermia on neuronal excitability. Our results suggest that hyperthermia increases hippocampal excitability, particularly in seizure-prone area CA3, by altering the intrinsic membrane properties of pyramidal cells and interneurons.

  14. High temperatures alter physiological properties of pyramidal cells and inhibitory interneurons in hippocampus.

    Science.gov (United States)

    Kim, Jennifer A; Connors, Barry W

    2012-01-01

    Temperature has multiple effects on neurons, yet little is known about the effects of high temperature on the physiology of mammalian central neurons. Hyperthermia can influence behavior and cause febrile seizures. We studied the effects of acute hyperthermia on the immature hippocampus in vitro by recording from pyramidal neurons and inhibitory oriens-lacunosum moleculare (O-LM) interneurons (identified by green fluorescent protein (GFP) expression in the GIN mouse line). Warming to 41°C caused depolarization, spontaneous action potentials, reduced input resistance and membrane time constant, and increased spontaneous synaptic activity of most pyramidal cells and O-LM interneurons. Pyramidal neurons of area CA3 were more strongly excited by hyperthermia than those of area CA1. About 90% of O-LM interneurons in both CA1 and CA3 increased their firing rates at hyperthermic temperatures; interneurons in CA3 fired faster than those in CA1 on average. Blockade of fast synaptic transmission did not abolish the effect of hyperthermia on neuronal excitability. Our results suggest that hyperthermia increases hippocampal excitability, particularly in seizure-prone area CA3, by altering the intrinsic membrane properties of pyramidal cells and interneurons.

  15. Postsynaptic blockade of inhibitory postsynaptic currents by plasmin in CA1 pyramidal cells of rat hippocampus.

    Science.gov (United States)

    Mizutani, A; Tanaka, T; Saito, H; Matsuki, N

    1997-06-27

    We have shown previously that plasmin facilitated the generation of long-term potentiation (LTP) in CA1 and dentate region of rat hippocampus. In the present study, we investigated the effects of plasmin on postsynaptic currents in CA1 pyramidal neurons of rat hippocampal slices. Plasmin (100 nM) had no effect on NMDA nor on non-NMDA receptor-mediated excitatory postsynaptic currents. However, plasmin significantly decreased GABA(A) receptor-mediated inhibitory postsynaptic currents. This effect of plasmin disappeared when intracellular Ca2+ was strongly chelated with BAPTA. Furthermore, plasmin attenuated the GABA-induced currents in CA1 pyramidal cells. These results suggest that the STP-enhancing effect of plasmin is due to a blockade of postsynaptic GABA(A) responses and that an increase in intracellular Ca2+ by plasmin may be involved in its mechanism.

  16. The Pyramidal Capacitated Vehicle Routing Problem

    DEFF Research Database (Denmark)

    Lysgaard, Jens

    This paper introduces the Pyramidal Capacitated Vehicle Routing Problem (PCVRP) as a restricted version of the Capacitated Vehicle Routing Problem (CVRP). In the PCVRP each route is required to be pyramidal in a sense generalized from the Pyramidal Traveling Salesman Problem (PTSP). A pyramidal...... found in many optimal solutions to CVRP instances. An optimal solution to the PCVRP may therefore be useful in itself as a heuristic solution to the CVRP. Further, an attempt can be made to find an even better CVRP solution by solving a TSP, possibly leading to a non-pyramidal route, for each...... of the routes in the PCVRP solution. This paper develops an exact branch-and-cut-and-price (BCP) algorithm for the PCVRP. At the pricing stage, elementary routes can be computed in pseudo-polynomial time in the PCVRP, unlike in the CVRP. We have therefore implemented pricing algorithms that generate only...

  17. Network state-dependent inhibition of identified hippocampal CA3 axo-axonic cells in vivo.

    Science.gov (United States)

    Viney, Tim J; Lasztoczi, Balint; Katona, Linda; Crump, Michael G; Tukker, John J; Klausberger, Thomas; Somogyi, Peter

    2013-12-01

    Hippocampal sharp waves are population discharges initiated by an unknown mechanism in pyramidal cell networks of CA3. Axo-axonic cells (AACs) regulate action potential generation through GABAergic synapses on the axon initial segment. We found that CA3 AACs in anesthetized rats and AACs in freely moving rats stopped firing during sharp waves, when pyramidal cells fire most. AACs fired strongly and rhythmically around the peak of theta oscillations, when pyramidal cells fire at low probability. Distinguishing AACs from other parvalbumin-expressing interneurons by their lack of detectable SATB1 transcription factor immunoreactivity, we discovered a somatic GABAergic input originating from the medial septum that preferentially targets AACs. We recorded septo-hippocampal GABAergic cells that were activated during hippocampal sharp waves and projected to CA3. We hypothesize that inhibition of AACs, and the resulting subcellular redistribution of inhibition from the axon initial segment to other pyramidal cell domains, is a necessary condition for the emergence of sharp waves promoting memory consolidation.

  18. Neuroprotective effects of inhibiting N-methyl-D-aspartate receptors, P2X receptors and the mitogen-activated protein kinase cascade: a quantitative analysis in organotypical hippocampal slice cultures subjected to oxygen and glucose deprivation.

    Science.gov (United States)

    Rundén-Pran, E; Tansø, R; Haug, F M; Ottersen, O P; Ring, A

    2005-01-01

    Cell death was assessed by quantitative analysis of propidium iodide uptake in rat hippocampal slice cultures transiently exposed to oxygen and glucose deprivation, an in vitro model of brain ischemia. The hippocampal subfields CA1 and CA3, and fascia dentata were analyzed at different stages from 0 to 48 h after the insult. Cell death appeared at 3 h and increased steeply toward 12 h. Only a slight additional increase in propidium iodide uptake was seen at later intervals. The mitogen-activated protein kinases extracellular signal-regulated kinase 1 and extracellular signal-regulated kinase 2 were activated immediately after oxygen and glucose deprivation both in CA1 and in CA3/fascia dentata. Inhibition of the specific mitogen-activated protein kinase activator mitogen-activated protein kinase kinase by PD98059 or U0126 offered partial protection against oxygen and glucose deprivation-induced cell damage. The non-selective P2X receptor antagonist suramin gave neuroprotection of the same magnitude as the N-methyl-D-aspartate channel blocker MK-801 (approximately 70%). Neuroprotection was also observed with the P2 receptor blocker PPADS. Immunogold data indicated that hippocampal slice cultures (like intact hippocampi) express several isoforms of P2X receptors at the synaptic level, consistent with the idea that the effects of suramin and PPADS are mediated by P2X receptors. Virtually complete neuroprotection was obtained by combined blockade of N-methyl-D-aspartate receptors, P2X receptors, and mitogen-activated protein kinase kinase. Both P2X receptors and N-methyl-D-aspartate receptors mediate influx of calcium. Our results suggest that inhibition of P2X receptors has a neuroprotective potential similar to that of inhibition of N-methyl-D-aspartate receptors. In contrast, our comparative analysis shows that only partial protection can be achieved by inhibiting the extracellular signal-regulated kinase 1/2 mitogen-activated protein kinase cascade, one of the

  19. Recruitment of Perisomatic Inhibition during Spontaneous Hippocampal Activity In Vitro.

    Directory of Open Access Journals (Sweden)

    Anna Beyeler

    Full Text Available It was recently shown that perisomatic GABAergic inhibitory postsynaptic potentials (IPSPs originating from basket and chandelier cells can be recorded as population IPSPs from the hippocampal pyramidal layer using extracellular electrodes (eIPSPs. Taking advantage of this approach, we have investigated the recruitment of perisomatic inhibition during spontaneous hippocampal activity in vitro. Combining intracellular and extracellular recordings from pyramidal cells and interneurons, we confirm that inhibitory signals generated by basket cells can be recorded extracellularly, but our results suggest that, during spontaneous activity, eIPSPs are mostly confined to the CA3 rather than CA1 region. CA3 eIPSPs produced the powerful time-locked inhibition of multi-unit activity expected from perisomatic inhibition. Analysis of the temporal dynamics of spike discharges relative to eIPSPs suggests significant but moderate recruitment of excitatory and inhibitory neurons within the CA3 network on a 10 ms time scale, within which neurons recruit each other through recurrent collaterals and trigger powerful feedback inhibition. Such quantified parameters of neuronal interactions in the hippocampal network may serve as a basis for future characterisation of pathological conditions potentially affecting the interactions between excitation and inhibition in this circuit.

  20. Mu opioid receptors are in discrete hippocampal interneuron subpopulations.

    Science.gov (United States)

    Drake, Carrie T; Milner, Teresa A

    2002-01-01

    In the rat hippocampal formation, application of mu opioid receptor (MOR) agonists disinhibits principal cells, promoting excitation-dependent processes such as epileptogenesis and long-term potentiation. However, the precise location of MORs in particular inhibitory circuits, has not been determined, and the roles of MORs in endogenous functioning are unclear. To address these issues, the distribution of MOR-like immunoreactivity (-li) was examined in several populations of inhibitory hippocampal neurons in the CA1 region using light and electron microscopy. We found that MOR-li was present in many parvalbumin-containing basket cells, but absent from cholecystokinin-labeled basket cells. MOR-li was also commonly in interneurons containing somatostatin-li or neuropeptide Y-li that resembled the "oriens-lacunosum-moleculare" (O-LM) interneurons innervating pyramidal cell distal dendrites. Finally, MOR-li was in some vasoactive intestinal peptide- or calretinin-containing profiles resembling interneurons that primarily innervate other interneurons. These findings indicate that MOR-containing neurons form a neurochemically and functionally heterogeneous subset of hippocampal GABAergic neurons. MORs are most frequently on interneurons that are specialized to inhibit pyramidal cells, and are on a limited number of interneurons that target other interneurons. Moreover, the distribution of MORs to different neuronal types in several laminae, some relatively far from endogenous opioids, suggests normal functional roles that are different from the actions seen with exogenous agonists such as morphine.

  1. Hippocampal corticosterone receptors and novelty-induced behavioral activity : effect of kainic acid lesion in the hippocampus

    NARCIS (Netherlands)

    Nyakas, C; De Kloet, E R; Veldhuis, H D; Bohus, B

    1983-01-01

    Rats were injected bilaterally in the dorsal and ventral hippocampus with kainic acid (KA) or with artificial CSF and their behavior and brain corticosterone (B) receptor systems were studied. The hippocampal KA injection destroyed part of the pyramidal neurons and of the dentate gyrus neurons. Thes

  2. The transcriptional repressor Zbtb20 is essential for specification of hippocampal projection neurons and territory in mice

    DEFF Research Database (Denmark)

    Rosenthal, Eva Helga

    for specification of both hippocampal pyramidal neurons and territory in a mouse knockout model. Homozygous Zbtb20-/- mice are viable at birth, but display dwarfism and die during the first month of postnatal life. Characterization of the Zbtb20-/- brain phenotype reveals a small vestigial hippocampus...

  3. The transcriptional repressor Zbtb20 is essential for specification of hippocampal projection neurons and territory in mice

    DEFF Research Database (Denmark)

    Rosenthal, Eva Helga

    for specification of both hippocampal pyramidal neurons and territory in a mouse knockout model. Homozygous Zbtb20-/- mice are viable at birth, but display dwarfism and die during the first month of postnatal life. Characterization of the Zbtb20-/- brain phenotype reveals a small vestigial hippocampus...... as an essential regulator of various aspects of neuronal development and corticogenesis in the hippocampus....

  4. Influence of environmental enrichment on hippocampal synapses in adolescent offspring of mothers exposed to prenatal stress

    Institute of Scientific and Technical Information of China (English)

    Yaojin Peng; Xiaohong Jian; Lihua Liu; Jianbin Tong; Deliang Lei

    2011-01-01

    Environmental enrichment attenuates hippocampal synaptic injury induced by prenatal stress in offspring.However, the influence of hippocampal synaptic changes and regional differences in prenatal stress remains poorly understood.The present study induced stress in Sprague Dawley rats, which were at gestational age 13 19 days.Following weaning, the offspring were raised in an enriched environment to establish models of stress+enriched environment.Dendritic spine density and synaptophysin expression were detected in hippocampal neurons using Golgi staining and western blot analysis, respectively.Results showed that enriched environment increased dendritic spine density of apical dendrites in CA1 pyramidal cells and basal dendrites of granular cells in the outer layer of the dentate gyrus.In addition, hippocampal synaptophysin expression increased and the effects of prenatal stress on neuronal dendritic spines were reversed in adolescence.

  5. Oxygen/glucose deprivation induces a reduction in synaptic AMPA receptors on hippocampal CA3 neurons mediated by mGluR1 and adenosine A3 receptors.

    OpenAIRE

    Dennis, Siobhan; Jaafari, Nadia; Cimarosti, Helena; Hanley, Jonathan G.; Henley, Jeremy M.; Mellor, Jack R.

    2011-01-01

    Hippocampal CA1 pyramidal neurons are highly sensitive to ischemic damage, whereas neighboring CA3 pyramidal neurons are less susceptible. It is proposed that switching of AMPA receptor (AMPAR) subunits on CA1 neurons during an in vitro model of ischemia, oxygen/glucose deprivation (OGD), leads to an enhanced permeability of AMPARs to Ca2+, resulting in delayed cell death. However, it is unclear whether the same mechanisms exist in CA3 neurons and whether this underlies the differential sensi...

  6. Oxygen/glucose Deprivation Induces a Reduction in Synaptic AMPA Receptors on Hippocampal CA3 Neurons Mediated by mGluR1 and A3 Receptors

    OpenAIRE

    Dennis, Siobhan H.; Jaafari, Nadia; Cimarosti, Helena; Hanley, Jonathan G.; Henley, Jeremy M.; Mellor, Jack R.

    2011-01-01

    Hippocampal CA1 pyramidal neurons are highly sensitive to ischemic damage, whereas neighbouring CA3 pyramidal neurons are less susceptible. It is proposed that switching of AMPA receptor (AMPAR) subunits on CA1 neurons during an in vitro model of ischemia, oxygen/glucose deprivation (OGD), leads to an enhanced permeability of AMPARs to Ca2+ resulting in delayed cell death. However, it is unclear if the same mechanisms exist in CA3 neurons and whether this underlies the differential sensitivit...

  7. NMDA receptors and the differential ischemic vulnerability of hippocampal neurons.

    Science.gov (United States)

    Gee, Christine E; Benquet, Pascal; Raineteau, Olivier; Rietschin, Lotty; Kirbach, Sebastian W; Gerber, Urs

    2006-05-01

    Transient cerebral ischemia causes an inhomogeneous pattern of cell death in the brain. We investigated mechanisms, which may underlie the greater susceptibility of hippocampal CA1 vs. CA3 pyramidal cells to ischemic insult. Using an in vitro oxygen-glucose deprivation (OGD) model of ischemia, we found that N-methyl-D-aspartate (NMDA) responses were enhanced in the more susceptible CA1 pyramidal cells and transiently depressed in the resistant CA3 pyramidal cells. The long-lasting potentiation of NMDA responses in CA1 cells was associated with delayed cell death and was prevented by blocking tyrosine kinase-dependent up-regulation of NMDA receptor function. In CA3 cells, the energy deprivation-induced transient depression of NMDA responses was converted to potentiation by blocking protein phosphatase signalling. These results suggest that energy deprivation differentially shifts the intracellular equilibrium between the tyrosine kinase and phosphatase activities that modulate NMDA responses in CA1 and CA3 pyramidal cells. Therapeutic modulation of tyrosine phosphorylation may thus prove beneficial in mitigating ischemia-induced neuronal death in vulnerable brain areas.

  8. Maskless inverted pyramid texturization of silicon.

    Science.gov (United States)

    Wang, Yan; Yang, Lixia; Liu, Yaoping; Mei, Zengxia; Chen, Wei; Li, Junqiang; Liang, Huili; Kuznetsov, Andrej; Xiaolong, Du

    2015-06-02

    We discovered a technical solution of such outstanding importance that it can trigger new approaches in silicon wet etching processing and, in particular, photovoltaic cell manufacturing. The so called inverted pyramid arrays, outperforming conventional pyramid textures and black silicon because of their superior light-trapping and structure characteristics, can currently only be achieved using more complex techniques involving lithography, laser processing, etc. Importantly, our data demonstrate a feasibility of inverted pyramidal texturization of silicon by maskless Cu-nanoparticles assisted etching in Cu(NO3)2 / HF / H2O2 / H2O solutions and as such may have significant impacts on communities of fellow researchers and industrialists.

  9. Mixed neurotransmission in the hippocampal mossy fibers

    Directory of Open Access Journals (Sweden)

    Agnieszka eMuenster-Wandowski

    2013-11-01

    Full Text Available The hippocampal mossy fibers (MFs, the axons of the granule cells of the dentate gyrus, innervate mossy cells and interneurons in the hilus on its way to CA3 where they innervate interneurons and pyramidal cells. Synapses on each target cell have distinct anatomical and functional characteristics. In recent years, the paradigmatic view of the MF synapses being only glutamatergic and, thus, excitatory has been questioned. Several laboratories have provided data supporting the hypothesis that the MFs can transiently release GABA during development and, in the adult, after periods of enhanced excitability. This transient glutamate-GABA co-transmission coincides with the transient expression of the machinery for the synthesis and release of GABA in the glutamatergic granule cells. Although some investigators have deemed this evidence controversial, new data has appeared with direct evidence of co-release of glutamate and GABA from single, identified MF boutons. However, this must still be confirmed by other groups and with other methodologies. A second, intriguing observation is that MF activation produced fast spikelets followed by excitatory postsynaptic potentials in a number of pyramidal cells, which, unlike the spikelets, underwent frequency potentiation and were strongly depressed by activation of metabotropic glutamate receptors. The spikelets persisted during blockade of chemical transmission and were suppressed by the gap junction blocker carbenoxolone. These data is consistent with the hypothesis of mixed electrical-chemical synapses between MFs and some pyramidal cells. Dye coupling between these types of principal cells and ultrastructural studies showing the co-existence of AMPA receptors and connexin 36 in this synapse corroborate their presence. A deeper consideration of mixed neurotransmission taking place in this synapse may expand our search and understanding of communication channels between different regions of the mammalian CNS.

  10. Effect of brain-derived neurotrophic factor haploinsufficiency on stress-induced remodeling of hippocampal neurons.

    Science.gov (United States)

    Magariños, A M; Li, C J; Gal Toth, J; Bath, K G; Jing, D; Lee, F S; McEwen, B S

    2011-03-01

    Chronic restraint stress (CRS) induces the remodeling (i.e., retraction and simplification) of the apical dendrites of hippocampal CA3 pyramidal neurons in rats, suggesting that intrahippocampal connectivity can be affected by a prolonged stressful challenge. Since the structural maintenance of neuronal dendritic arborizations and synaptic connectivity requires neurotrophic support, we investigated the potential role of brain derived neurotrophic factor (BDNF), a neurotrophin enriched in the hippocampus and released from neurons in an activity-dependent manner, as a mediator of the stress-induced dendritic remodeling. The analysis of Golgi-impregnated hippocampal sections revealed that wild type (WT) C57BL/6 male mice showed a similar CA3 apical dendritic remodeling in response to three weeks of CRS to that previously described for rats. Haploinsufficient BDNF mice (BDNF(±) ) did not show such remodeling, but, even without CRS, they presented shorter and simplified CA3 apical dendritic arbors, like those observed in stressed WT mice. Furthermore, unstressed BDNF(±) mice showed a significant decrease in total hippocampal volume. The dendritic arborization of CA1 pyramidal neurons was not affected by CRS or genotype. However, only in WT mice, CRS induced changes in the density of dendritic spine shape subtypes in both CA1 and CA3 apical dendrites. These results suggest a complex role of BDNF in maintaining the dendritic and spine morphology of hippocampal neurons and the associated volume of the hippocampal formation. The inability of CRS to modify the dendritic structure of CA3 pyramidal neurons in BDNF(±) mice suggests an indirect, perhaps permissive, role of BDNF in mediating hippocampal dendritic remodeling.

  11. Effects of L-3-n-butylphthalide on caspase-3 and nuclear factor kappa-B expression in primary basal forebrain and hippocampal cultures after beta-amyloid peptide 1-42 treatment

    Institute of Scientific and Technical Information of China (English)

    Ruixia Wang; Yong Zhang; Liangliang Jiang; Guozhao Ma; Qingxi Fu; Jialong Li; Peng Yan; Lunqian Shen; Yabo Feng; Chunxia Li; Zaiying Pang; Yuanxiao Cui; Chunfu Chen; Yifeng Du; Zhaokong Liu

    2009-01-01

    BACKGROUND: L-3-n-butylphthalide (L-NBP) can inhibit phosphorylation of tau protein and reduce the neurotoxicity of beta-amyloid peptide 1-42 (Aβ1-42).OBJECTIVE: To observe the neuroprotective effects of L-NBP on caspase-3 and nuclear factor kappa-B (NF-кB) expression in a rat model of Alzheimer's disease.DESIGN, TIME AND SETTING: A cell experiment was performed at the Central Laboratory of Provincial Hospital affiliated to Shandong University between January 2008 and August 2008.MATERIALS: L-NBP (purity>98%) was provided by Shijiazhuang Pharma Group NBP Pharmaceutical Company Limited. Aβ1-42, 3-[4,5-dimethylthiazolo-2]-2,5 iphenyltetrazolium bromide (MTT), and rabbit anti-Caspase-3 polyclonal antibody were provided by Cell Signaling, METHODS: Primary cultures were generated from rat basal forebrain and hippocampal neurons at 17 or 19 days of gestation. The cells were assigned into five groups: the control group, the Aβ1-42 group (2μmol/L), the Aβ1-42+0.1μmol/L L-NBP group, the Aβ1-42+1 μmol/L L-NBP group, and the Aβ1-42 + 10μmol/L L-NBP group. The neurons were treated with Aβ1-42 (2 μmol/L) alone or in combination with L-NBP (0.1, 1, 10μmol/L) for 48 hours. Cells in the control group were incubated in PBS.MAIN OUTCOME MEASURES: Morphologic changes were evaluated using inverted microscopy, Western blot.RESULTS: Induction with Aβ1-42 for 48 hours caused cell death and soma atrophy, and increased the high dose (P<0.05).CONCLUSION: Aβ1-42 is toxic to basal forebrain and hippocampal primary neurons; L-NBP protects against this toxicity and inhibits the induction of caspase-3 and NF-κB expression.

  12. FABRIC DEFECT DETECTION USING STEERABLE PYRAMID

    Directory of Open Access Journals (Sweden)

    S. Mythili

    2011-05-01

    Full Text Available In this paper, a novel idea is proposed for fabric defect detection. De- fects are detected in the fabric using steerable pyramid along with a defect detection algorithm. Various steerable pyramid of four size 256*256, 128*128, 64*64, 32*32 and with four orientation bands 00,450, 900, 1350 are used. Utilizing a Steerable pyramid proved ade- quate in the representation of fabric images in multi-scale and multi- orientations; thus allowing defect detection algorithms to run more effectively. Defect detection algorithm identifies and locates the im- perfection in the defective sample using the statistics mean and stan- dard deviation. This statistics represents the relative amount of inten- sity in the texture and is sufficient to measure defects in the current model .The obtained result are compared with the existing methods wavelet based system and with Gaussian and Laplacian pyramid.

  13. Evaluation of the Green Egyptian Pyramid

    Directory of Open Access Journals (Sweden)

    Mohamed Gamal Ammar

    2012-12-01

    The research concluded to the need of developing the Egyptian pyramid system through studying more global systems, in addition to the need to benefit from the Egyptian experience stock of solutions and environmental treatments in ancient architecture.

  14. Waring’s Problem for Pyramidal Numbers

    Institute of Scientific and Technical Information of China (English)

    邓越凡; 杨振宁

    1994-01-01

    It has been proved that every positive integer is expressible as a sum of no more than eight pyramidal numbers P(m)=(m-1)m(m+1)/6.This paper reports on a computer calculation of the partition of integers from n=1 to 109 into pyramidal numbers.We find that no integer≤10°needs more than five pyramidal numbers for its partition,and only 241 of them do need five.We define J(n) as the least number of pyramidal numbers to partition n,and Nk(n) as the number of positive integers l less than or equal to n for which J(l)=k.Based on our numerical results we make conjectures about the asymptotic form of Nk(n) for n→∞

  15. Simulation of gene pyramiding in Drosophila melanogaster

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Gene pyramiding has been successfully practiced in plant breeding for developing new breeds or lines in which favorable genes from several different lines were integrated.But it has not been used in animal breeding,and some theoretical investigation and simulation analysis with respect to its strategies,feasibility and efficiency are needed before it can be implemented in animals.In this study,we used four different pure fines of Drosophila melanogaster,each of which is homozygous at a specific mutant gene with a visible effect on phenotype,to simulate the gene pyramiding process and analyze the duration and population size required in different pyramiding strategies.We finally got the ideal individuals,which are homozygous at the four target genes simultaneously.This study demonstrates that gene pyramiding is feasible in animal breeding and the interaction between genes may affect the final results.

  16. Catalyzing new product adoption at the base of the pyramid

    OpenAIRE

    Marinakis, Y.D.; Walsh, S. T.; Harms, R.

    2016-01-01

    One of the more perplexing of the entrepreneurial issues at the Base of the Pyramid (BoP) is how to catalyze new product adoption by BoP consumers. Because S-shaped adoption dynamics are the result of cultural transmission bias, the question can be rephrased as, how can an entrepreneur overcome conformity bias. We modified the Technology Acceptance Model (TAM) to include conformity bias. We then qualitatively applied the model to three examples from the literature, namely fuel stoves in Darfu...

  17. Work, gravitational energy and the Great Pyramid

    Science.gov (United States)

    Tort, A. C.

    2015-09-01

    According to the Greek historian Herodotus, it took a task force of 100 000 men and 20 years to build up the Great Pyramid of Gizeh or Khufu’s Pyramid. In this work we discuss an analytical solution obtained in the framework of basic Newtonian mechanics that allows us to check Herodotus’s statement. Numerical estimates are compared to more detailed calculations. An estimation of the dietary energy intake necessary to accomplish the task is also discussed.

  18. Inhibition of GABA release by presynaptic ionotropic GABA receptors in hippocampal CA3.

    Science.gov (United States)

    Axmacher, Nikolai; Draguhn, Andreas

    2004-02-09

    Vesicular transmitter release can be regulated by transmitter-gated ion channels at presynaptic axon terminals. The central inhibitory transmitter GABA acts on such presynaptic ionotropic receptors in various cells, including inhibitory interneurons. Here we report that GABA-mediated postsynaptic inhibitory currents in CA3 pyramidal cells of rat hippocampal slices are suppressed by agonists of GABAA receptors. The effect is present for both stimulus-induced and miniature IPSCs, indicating a reduction in the probability of vesicular release by presynaptic, action-potential-independent mechanisms. We conclude that the release of GABA from hippocampal CA3 interneurons is regulated by a negative feedback via presynaptic ionotropic GABA autoreceptors.

  19. Zinc enhances the inhibitory effects of strychnine-sensitive glycine receptors in mouse hippocampal neurons.

    Science.gov (United States)

    Zhang, Hai Xia; Thio, Liu Lin

    2007-12-01

    Although extracellular Zn(2+) is an endogenous biphasic modulator of strychnine-sensitive glycine receptors (GlyRs), the physiological significance of this modulation remains poorly understood. Zn(2+) modulation of GlyR may be especially important in the hippocampus where presynaptic Zn(2+) is abundant. Using cultured embryonic mouse hippocampal neurons, we examined whether 1 microM Zn(2+), a potentiating concentration, enhances the inhibitory effects of GlyRs activated by sustained glycine applications. Sustained 20 microM glycine (EC(25)) applications alone did not decrease the number of action potentials evoked by depolarizing steps, but they did in 1 microM Zn(2+). At least part of this effect resulted from Zn(2+) enhancing the GlyR-induced decrease in input resistance. Sustained 20 microM glycine applications alone did not alter neuronal bursting, a form of hyperexcitability induced by omitting extracellular Mg(2+). However, sustained 20 microM glycine applications depressed neuronal bursting in 1 microM Zn(2+). Zn(2+) did not enhance the inhibitory effects of sustained 60 microM glycine (EC(70)) applications in these paradigms. These results suggest that tonic GlyR activation could decrease neuronal excitability. To test this possibility, we examined the effect of the GlyR antagonist strychnine and the Zn(2+) chelator tricine on action potential firing by CA1 pyramidal neurons in mouse hippocampal slices. Co-applying strychnine and tricine slightly but significantly increased the number of action potentials fired during a depolarizing current step and decreased the rheobase for action potential firing. Thus Zn(2+) may modulate neuronal excitability normally and in pathological conditions such as seizures by potentiating GlyRs tonically activated by low agonist concentrations.

  20. Delayed hippocampal neuronal death in young gerbil following transient global cerebral ischemia is related to higher and longer-term expression of p63 in the ischemic hippocampus

    Directory of Open Access Journals (Sweden)

    Eun Joo Bae

    2015-01-01

    Full Text Available The tumor suppressor p63 is one of p53 family members and plays a vital role as a regulator of neuronal apoptosis in the development of the nervous system. However, the role of p63 in mature neuronal death has not been addressed yet. In this study, we first compared ischemia-induced effects on p63 expression in the hippocampal regions (CA1- 3 between the young and adult gerbils subjected to 5 minutes of transient global cerebral ischemia. Neuronal death in the hippocampal CA1 region of young gerbils was significantly slow compared with that in the adult gerbils after transient global cerebral ischemia. p63 immunoreactivity in the hippocampal CA1 pyramidal neurons in the sham-operated young group was significantly low compared with that in the sham-operated adult group. p63 immunoreactivity was apparently changed in ischemic hippocampal CA1 pyramidal neurons in both ischemia-operated young and adult groups. In the ischemia-operated adult groups, p63 immunoreactivity in the hippocampal CA1 pyramidal neurons was significantly decreased at 4 days post-ischemia; however, p63 immunoreactivity in the ischemia-operated young group was significantly higher than that in the ischemia-operated adult group. At 7 days post-ischemia, p63 immunoreactivity was decreased in the hippocampal CA1 pyramidal neurons in both ischemia-operated young and adult groups. Change patterns of p63 level in the hippocampal CA1 region of adult and young gerbils after ischemic damage were similar to those observed in the immunohistochemical results. These findings indicate that higher and longer-term expression of p63 in the hippocampal CA1 region of the young gerbils after ischemia/reperfusion may be related to more delayed neuronal death compared to that in the adults.

  1. Corticotropin-Releasing Hormone (CRH)-Containing Neurons in the Immature Rat Hippocampal Formation: Light and Electron Microscopic Features and Colocalization With Glutamate Decarboxylase and Parvalbumin

    OpenAIRE

    Yan, Xiao-Xin; Toth, Zsolt; Schultz, Linda; Ribak, Charles E; Tallie Z. Baram

    1998-01-01

    Corticotropin-releasing hormone (CRH) excites hippocampal neurons and induces death of selected CA3 pyramidal cells in immature rats. These actions of CRH require activation of specific receptors that are abundant in CA3 during early postnatal development. Given the dramatic effects of CRH on hippocampal neurons and the absence of CRH-containing afferents to this region, we hypothesized that a significant population of CRHergic neurons exists in developing rat hippocampus. This study defined ...

  2. Delayed hippocampal neuronal death in young gerbil following transient global cerebral ischemia is related to higher and longer-term expression of p63 in the ischemic hippocampus

    Institute of Scientific and Technical Information of China (English)

    Eun Joo Bae; Seongkweon Hong; Dong Won Kim; Jun Hwi Cho; Yun Lyul Lee; Moo-Ho Won; Joon Ha Park; Bai Hui Chen; Bing Chun Yan; Bich Na Shin; Jeong Hwi Cho; In Hye Kim; Ji Hyeon Ahn; Jae Chul Lee; Hyun-Jin Tae

    2015-01-01

    The tumor suppressor p63 is one of p53 family members and plays a vital role as a regulator of neuronal apoptosis in the development of the nervous system. However, the role of p63 in mature neuronal death has not been addressed yet. In this study, we ifrst compared ischemia-in-duced effects on p63 expression in the hippocampal regions (CA1–3) between the young and adult gerbils subjected to 5 minutes of transient global cerebral ischemia. Neuronal death in the hippocampal CA1 region of young gerbils was signiifcantly slow compared with that in the adult gerbils after transient global cerebral ischemia. p63 immunoreactivity in the hippocampal CA1 pyramidal neurons in the sham-operated young group was signiifcantly low compared with that in the sham-operated adult group. p63 immunoreactivity was apparently changed in ischemic hippocampal CA1 pyramidal neurons in both ischemia-operated young and adult groups. In the ischemia-operated adult groups, p63 immunoreactivity in the hippocampal CA1 pyramidal neurons was signiifcantly decreased at 4 days post-ischemia;however, p63 immunoreactivity in the ischemia-operated young group was signiifcantly higher than that in the ischemia-operated adult group. At 7 days post-ischemia, p63 immunoreactivity was decreased in the hippocampal CA1 pyramidal neurons in both ischemia-operated young and adult groups. Change patterns of p63 level in the hippocampal CA1 region of adult and young gerbils after ischemic damage were similar to those observed in the immunohistochemical results. These ifndings indicate that higher and longer-term expression of p63 in the hippocampal CA1 region of the young gerbils after ischemia/reperfusion may be related to more delayed neuronal death compared to that in the adults.

  3. An Improved Pyramid for Spatially Scalable Video Coding

    OpenAIRE

    2005-01-01

    This paper discusses an improved pyramid for spatially scalable video coding. We introduce additional update steps in the analysis and the synthesis of the Laplacian pyramid. Our pyramid is able to control efficiently the quantization noise energy in the reconstruction. Hence, it provides improved coding performance when compared to the standard Laplacian pyramid. Moreover, our pyramid does not require biorthogonal filters as they should be used for the frame reconstruction of the Laplacian p...

  4. Prolonged exposure to WIN55,212-2 causes downregulation of the CB1 receptor and the development of tolerance to its anticonvulsant effects in the hippocampal neuronal culture model of acquired epilepsy.

    Science.gov (United States)

    Blair, Robert E; Deshpande, Laxmikant S; Sombati, Sompong; Elphick, Maurice R; Martin, Billy R; DeLorenzo, Robert J

    2009-09-01

    Cannabinoids have been shown to cause CB1-receptor-dependent anticonvulsant activity in both in vivo and in vitro models of status epilepticus (SE) and acquired epilepsy (AE). It has been further demonstrated in these models that the endocannabinoid system functions in a tonic manner to suppress seizure discharges through a CB1-receptor-dependent pathway. Although acute cannabinoid treatment has anticonvulsant activity, little is known concerning the effects of prolonged exposure to CB1 agonists and development of tolerance on the epileptic phenotype. This study was carried out to evaluate the effects of prolonged exposure to the CB1 agonist WIN55,212-2 on seizure activity in a hippocampal neuronal culture model of low-Mg(2+) induced spontaneous recurrent epileptiform discharges (SREDs). Following low-Mg(2+) induced SREDs, cultures were returned to maintenance media containing 10, 100 or 1000 nM WIN55,212-2 from 4 to 24 h. Whole-cell current-clamp analysis of WIN55,212-2 treated cultures revealed a concentration-dependent increase in SRED frequency. Immunocytochemical staining revealed that WIN55,212-2 treatment induced a concentration-dependent downregulation of the CB1 receptor in neuronal processes and at both glutamatergic and GABAergic presynaptic terminals. Prolonged exposure to the inactive enantiomer WIN55,212-3 in low-Mg(2+) treated cultures had no effect on the frequency of SREDs or CB1 receptor staining. The results from this study further substantiate a role for a tonic CB1-receptor-dependent endocannabinoid regulation of seizure discharge and suggest that prolonged exposure to cannabinoids results in the development of tolerance to the anticonvulsant effects of cannabinoids and an exacerbation of seizure activity in the epileptic phenotype.

  5. Prolonged exposure to WIN55,212-2 causes down-regulation of the CB1 receptor and the development of tolerance to its anticonvulsant effects in the hippocampal neuronal culture model of acquired epilepsy

    Science.gov (United States)

    Blair, Robert E.; Deshpande, Laxmikant S.; Sombati, Sompong; Elphick, Maurice R.; Martin, Billy R.; DeLorenzo, Robert J.

    2009-01-01

    Summary Cannabinoids have been shown to cause CB1-receptor dependent anticonvulsant activity in both in vivo and in vitro models of status epilepticus (SE) and acquired epilepsy (AE). It has been further demonstrated in these models that the endocannabinoid system functions in a tonic manner to suppress seizure discharges through a CB1-receptor dependent pathway. Although acute cannabinoid treatment has anticonvulsant activity, little is known concerning the effects of prolonged exposure to CB1 agonists and development of tolerance on the epileptic phenotype. This study was carried out to evaluate the effects of prolonged exposure to the CB1 agonist WIN55,212-2 on seizure activity in a hippocampal neuronal culture model of low-Mg2+ induced spontaneous recurrent epileptiform discharges (SREDs). Following low-Mg2+ induced SREDs, cultures were returned to maintenance media containing 10, 100 or 1000 nM WIN55,212-2 from 4 to 24 hours. Whole-cell current-clamp analysis of WIN55,212-2 treated cultures revealed a concentration-dependent increase in SRED frequency. Immunocytochemical staining revealed that WIN55,212-2 treatment induced a concentration-dependent down-regulation of the CB1 receptor in neuronal processes and at both glutamatergic and GABAergic presynaptic terminals. Prolonged exposure to the inactive enantiomer WIN55,212-3 in low-Mg2+ treated cultures had no effect on the frequency of SREDs or CB1 receptor staining. The results from this study further substantiate a role for a tonic CB1 receptor-dependent endocannabinoid regulation of seizure discharge and suggest that prolonged exposure to cannabinoids results in the development of tolerance to the anticonvulsant effects of cannabinoids and an exacerbation of seizure activity in the epileptic phenotype. PMID:19540252

  6. Empathy in hippocampal amnesia.

    Science.gov (United States)

    Beadle, J N; Tranel, D; Cohen, N J; Duff, M C

    2013-01-01

    Empathy is critical to the quality of our relationships with others and plays an important role in life satisfaction and well-being. The scientific investigation of empathy has focused on characterizing its cognitive and neural substrates, and has pointed to the importance of a network of brain regions involved in emotional experience and perspective taking (e.g., ventromedial prefrontal cortex, amygdala, anterior insula, cingulate). While the hippocampus has rarely been the focus of empathy research, the hallmark properties of the hippocampal declarative memory system (e.g., representational flexibility, relational binding, on-line processing capacity) make it well-suited to meet some of the crucial demands of empathy, and a careful investigation of this possibility could make a significant contribution to the neuroscientific understanding of empathy. The present study is a preliminary investigation of the role of the hippocampal declarative memory system in empathy. Participants were three patients (1 female) with focal, bilateral hippocampal (HC) damage and severe declarative memory impairments and three healthy demographically matched comparison participants. Empathy was measured as a trait through a battery of gold standard questionnaires and through on-line ratings and prosocial behavior in response to a series of empathy inductions. Patients with hippocampal amnesia reported lower cognitive and emotional trait empathy than healthy comparison participants. Unlike healthy comparison participants, in response to the empathy inductions hippocampal patients reported no increase in empathy ratings or prosocial behavior. The results provide preliminary evidence for a role for hippocampal declarative memory in empathy.

  7. Multisite electrophysiological recordings by self-assembled loose-patch-like junctions between cultured hippocampal neurons and mushroom-shaped microelectrodes

    Science.gov (United States)

    Shmoel, Nava; Rabieh, Noha; Ojovan, Silviya M.; Erez, Hadas; Maydan, Eilon; Spira, Micha E.

    2016-01-01

    Substrate integrated planar microelectrode arrays is the “gold standard” method for millisecond-resolution, long-term, large-scale, cell-noninvasive electrophysiological recordings from mammalian neuronal networks. Nevertheless, these devices suffer from drawbacks that are solved by spike-detecting, spike-sorting and signal-averaging techniques which rely on estimated parameters that require user supervision to correct errors, merge clusters and remove outliers. Here we show that primary rat hippocampal neurons grown on micrometer sized gold mushroom-shaped microelectrodes (gMμE) functionalized simply by poly-ethylene-imine/laminin undergo self-assembly processes to form loose patch-like hybrid structures. More than 90% of the hybrids formed in this way record monophasic positive action potentials (APs). Of these, 34.5% record APs with amplitudes above 300 μV and up to 5,085 μV. This self-assembled neuron-gMμE configuration improves the recording quality as compared to planar MEA. This study characterizes and analyzes the electrophysiological signaling repertoire generated by the neurons-gMμE configuration, and discusses prospects to further improve the technology. PMID:27256971

  8. Energy deprivation transiently enhances rhythmic inhibitory events in the CA3 hippocampal network in vitro.

    Science.gov (United States)

    Gee, C E; Benquet, P; Demont-Guignard, S; Wendling, F; Gerber, U

    2010-07-14

    Oxygen glucose deprivation (OGD) leads to rapid suppression of synaptic transmission. Here we describe an emergence of rhythmic activity at 8 to 20 Hz in the CA3 subfield of hippocampal slice cultures occurring for a few minutes prior to the OGD-induced cessation of evoked responses. These oscillations, dominated by inhibitory events, represent network activity, as they were abolished by tetrodotoxin. They were also completely blocked by the GABAergic antagonist picrotoxin, and strongly reduced by the glutamatergic antagonist NBQX. Applying CPP to block NMDA receptors had no effect and neither did UBP302, an antagonist of GluK1-containing kainate receptors. The gap junction blocker mefloquine disrupted rhythmicity. Simultaneous whole-cell voltage-clamp recordings from neighboring or distant CA3 pyramidal cells revealed strong cross-correlation of the incoming rhythmic activity. Interneurons in the CA3 area received similar correlated activity. Interestingly, oscillations were much less frequently observed in the CA1 area. These data, together with the observation that the recorded activity consists primarily of inhibitory events, suggest that CA3 interneurons are important for generating these oscillations. This transient increase in inhibitory network activity during OGD may represent a mechanism contributing to the lower vulnerability to ischemic insults of the CA3 area as compared to the CA1 area.

  9. Fluctuating inhibitory inputs promote reliable spiking at theta frequencies in hippocampal interneurons

    OpenAIRE

    Duluxan eSritharan; Frances K Skinner

    2012-01-01

    Theta frequency (4-12 Hz) rhythms in the hippocampus play important roles in learning and memory. CA1 interneurons located at the stratum lacunosum-moleculare and radiatum junction (LM/RAD) are thought to contribute to hippocampal theta population activities by rhythmically pacing pyramidal cells with inhibitory postsynaptic potentials. This implies that LM/RAD cells need to fire reliably at theta frequencies in vivo. To determine whether this could occur, we use biophysically-based LM/RAD mo...

  10. Multiple forms of long-term synaptic plasticity at hippocampal mossy fiber synapses onto interneurons

    OpenAIRE

    Galván, Emilio J; Cosgrove, Kathleen E.; Barrionuevo, Germán

    2010-01-01

    The hippocampal mossy fiber (MF) pathway originates from the dentate gyrus granule cells and provides a powerful excitatory synaptic drive to neurons in the dentate gyrus hilus and area CA3. Much of the early work on the MF pathway focused on its electrophysiological properties, and ability to drive CA3 pyramidal cell activity. Over the last ten years, however, a new focus on the synaptic interaction between granule cells with inhibitory interneurons has emerged. These data have revealed an i...

  11. Effect of Brain-Derived Neurotrophic Factor Haploinsufficiency on Stress-Induced Remodeling of Hippocampal Neurons

    OpenAIRE

    Magariños, A.M.; Li, C. J.; Toth, J. Gal; Bath, K.G.; Jing, D; Lee, F S; MCEWEN, B. S.

    2011-01-01

    Chronic restraint stress (CRS) induces the remodeling (i.e., retraction and simplification) of the apical dendrites of hippocampal CA3 pyramidal neurons in rats, suggesting that intrahippocampal connectivity can be affected by a prolonged stressful challenge. Since the structural maintenance of neuronal dendritic arborizations and synaptic connectivity requires neurotrophic support, we investigated the potential role of brain derived neurotrophic factor (BDNF), a neurotrophin enriched in the ...

  12. Terminal Field and Firing Selectivity of Cholecystokinin-Expressing Interneurons in the Hippocampal CA3 Area

    OpenAIRE

    Lasztóczi, Bálint; Tukker, John J.; Somogyi, Peter; Klausberger, Thomas

    2011-01-01

    Hippocampal oscillations reflect coordinated neuronal activity on many timescales. Distinct types of GABAergic interneuron participate in the coordination of pyramidal cells over different oscillatory cycle phases. In the CA3 area, which generates sharp waves and gamma oscillations, the contribution of identified GABAergic neurons remains to be defined. We have examined the firing of a family of cholecystokinin-expressing interneurons during network oscillations in urethane-anesthetized rats ...

  13. Effect of curcumin on AMPA and kainate receptor-mediated calcium influx in cultured rat hippocampal neurons%姜黄素对AMPA/KA受体介导大鼠海马神经元钙内流的影响

    Institute of Scientific and Technical Information of China (English)

    杜鹏; 彭伟锋; 刘剑英; 林豪杰; 马昱; 汪昕; 范薇

    2009-01-01

    目的 探讨姜黄素对α-氨基-3-羧基-5-甲基异恶唑-4-丙酸(AMPA)/海人酸(KA)受体介导大鼠海马神经元钙内流的影响.方法 选用胚胎17dSD鼠分离海马,离体培养海马神经元,借助活体钙荧光染色和激光共聚焦钙成像技术观察100μmol/LKA刺激海马神经元内钙的变化,不同浓度(5、10、15、30、50 μmol/L)姜黄素预孵育海马神经元30min对100μmol/L KA刺激下细胞内钙变化的影响,15 μmol/L姜黄素对不同浓度(10、30、50、100、200、300 μmol/L)KA刺激海马神经元内钙变化的影响.应用钴染色技术观察(30、100 μmol/L KA)刺激后海马神经元钴阳性染色细胞变化.姜黄素预孵育30min对KA刺激导致钴阳性染色细胞变化的影响.结果 不同浓度姜黄素预孵育30 min均可以明显缓解100 μmol/L或30 μmol/L KA导致的细胞内钙升高程度.差异均有统计学意义(P<0.05),其中15 μmol/L姜黄素作用最为明显.30μmol/L或100 μmol/LKA刺激均可以引起海马神经元钴染色阳性细胞增加,15 μmol/L姜黄素预处理30 min后明显减少钴染色阳性细胞,差异有统计学意义(P<0.05),而其他浓度(5 μmol/L或30 μmol/L)姜黄素未见明显影响.结论 一定浓度的姜黄素可以影响AMPA/KA受体介导大鼠海马神经元钙内流.这可能是姜黄素抗癫痫作用的一个机制.%Objective To investigate the effect of curcumin on alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and kainate (KA) receptor-mediated calcium influx in cultured rat hippocampal neurons. Methods The hippocampal neurons from SD rat embryos (17 days old) were cultured for 9 days, and fluorescent calcium chelator and confocal microscopy calcium imaging were used to observe the changes in intracellular free calcium in the neurons following stimulation with 100 μmol/L KA. The effect of curcumin pretreatment at different concentrations (10, 30, 50, 100, 200 and 300 μmol/L) for 30 min on 100 μmol/L KA

  14. Postnatal maturation of gamma-aminobutyric acidA and B-mediated inhibition in the CA3 hippocampal region of the rat.

    Science.gov (United States)

    Gaiarsa, J L; McLean, H; Congar, P; Leinekugel, X; Khazipov, R; Tseeb, V; Ben-Ari, Y

    1995-03-01

    In the adult central nervous system, GABAergic synaptic inhibition is known to play a crucial role in preventing the spread of excitatory glutamatergic activity. This inhibition is achieved by a membrane hyperpolarization through the activation of postsynaptic gamma-aminobutyric acidA (GABAA) and GABAB receptors. In addition, GABA also depress transmitter release acting through presynaptic GABAB receptors. Despite the wealth of data regarding the role of GABA in regulating the degree of synchronous activity in the adult, little is known about GABA transmission during early stages of development. In the following we report that GABA mediates most of the excitatory drive at early stages of development in the hippocampal CA3 region. Activation of GABAA receptors induces a depolarization and excitation of immature CA3 pyramidal neurons and increases intracellular Ca2+ ([Ca2+]i)] during the first postnatal week of life. During the same developmental period, the postsynaptic GABAB-mediated inhibition is poorly developed. In contrast, the presynaptic GABAB-mediated inhibition is well developed at birth and plays a crucial role in modulating the postsynaptic activity by depressing transmitter release at early postnatal stages. We have also shown that GABA plays a trophic role in the neuritic outgrowth of cultured hippocampal neurons.

  15. Influence of Slow Oscillation on Hippocampal Activity and Ripples Through Cortico-Hippocampal Synaptic Interactions, Analyzed by a Cortical-CA3-CA1 Network Model

    Directory of Open Access Journals (Sweden)

    Jiannis eTaxidis

    2013-02-01

    Full Text Available Hippocampal sharp wave-ripple complexes (SWRs involve the synchronous discharge of thousands of cells throughout the CA3-CA1-subiculum-entorhinal cortex axis. Their strong transient output affects cortical targets, rendering SWRs a possible means for memory transfer from the hippocampus to the neocortex for long-term storage. Neurophysiological observations of hippocampal activity modulation by the cortical slow oscillation (SO during deep sleep and anesthesia, and correlations between ripples and UP states, support the role of SWRs in memory consolidation through a cortico-hippocampal feedback loop. We couple a cortical network exhibiting SO with a hippocampal CA3-CA1 computational network model exhibiting SWRs, in order to model such cortico-hippocampal correlations and uncover important parameters and coupling mechanisms controlling them. The cortical oscillatory output entrains the CA3 network via connections representing the mossy fiber input, and the CA1 network via the temporoammonic pathway. The spiking activity in CA3 and CA1 is shown to depend on the excitation-to-inhibition ratio, induced by combining the two hippocampal inputs, with mossy fiber input controlling the UP-state correlation of CA3 population bursts and corresponding SWRs, whereas the temporoammonic input affects the overall CA1 spiking activity. Ripple characteristics and pyramidal spiking participation to SWRs are shaped by the strength of the Schaffer collateral drive. A set of in vivo recordings from the rat hippocampus confirms a model-predicted segregation of pyramidal cells into subgroups according to the SO state where they preferentially fire and their response to SWRs. These groups can potentially play distinct functional roles in the replay of spike sequences.

  16. Age-related changes of NGF, BDNF, parvalbumin and neuronal nitric oxide synthase immunoreactivity in the mouse hippocampal CA1 sector.

    Science.gov (United States)

    Hayakawa, Natsumi; Abe, Manami; Eto, Risa; Kato, Hiroyuki; Araki, Tsutomu

    2008-06-01

    We investigated the age-related alterations in nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), parvalbumin and neuronal nitric oxide synthase (nNOS) immunoreactivity of the mouse hippocampal CA1 sector. NGF and BDNF immunoreactivity was unchanged in the hippocampal CA1 pyramidal neurons from 2 to 50-59 weeks of birth. In contrast, a significant increase in the NGF and BDNF immunoreactivity was observed in glial cells of the hippocampal CA1 sector from 40-42 to 50-59 weeks of birth. On the other hand, the number of parvalbumin- and nNOS-positive interneurons was unchanged in the hippocampal CA1 sector during aging processes, except for a significant decrease of nNOS-positive interneurons 2 weeks of birth. Our results indicate that NGF and BDNF immunoreactivity was unaltered in the hippocampal CA1 pyramidal neurons during aging processes. In contrast, a significant increase in the NGF and BDNF immunoreactivity was observed in glial cells of the hippocampal CA1 sector during aging processes. The present study also shows that the number of parvalbumin- and nNOS-positive interneurons was unchanged in the hippocampal CA1 sector during aging processes, except for a significant decrease of nNOS-positive interneurons 2 weeks of birth. These results demonstrate that the expression of glial NGF and BDNF may play a key role for helping survival and maintenance of pyramidal neurons and neuronal functions in the hippocampal CA1 sector during aging processes. Furthermore, our findings suggest that parvalbumin- and nNOS-positive interneurons in the hippocampal CA1 sector are resistant to aging processes. Moreover, our findings suggest that nitric oxide synthesized by the nNOS may play some role for neuronal growth during postnatal development.

  17. Loss of mTOR repressors Tsc1 or Pten has divergent effects on excitatory and inhibitory synaptic transmission in single hippocampal neuron cultures.

    Directory of Open Access Journals (Sweden)

    Matthew C Weston

    2014-02-01

    Full Text Available The Pten and Tsc1 genes both encode proteins that repress mechanistic target of rapamycin (mTOR signaling. Disruption of either gene in the brain results in epilepsy and autism-like symptoms in humans and mouse models, therefore it is important to understand the molecular and physiological events that lead from gene disruption to disease phenotypes. Given the similar roles these two molecules play in the regulation of cellular growth and the overlap in the phenotypes that result from their loss, we predicted that the deletion of either the Pten or Tsc1 gene from hippocampal neurons would have similar effects on neuronal morphology and synaptic transmission. Accordingly, we found that loss of either Pten or Tsc1 caused comparable increases in soma size, dendrite length and action potential properties. However, the effects of Pten and Tsc1 loss on synaptic transmission were different. Loss of Pten lead to an increase in both excitatory and inhibitory neurotransmission, while loss of Tsc1 did not affect excitatory neurotransmission and reduced inhibitory transmission by decreasing mIPSC amplitude. Although the loss of Pten or Tsc1 both increased downstream mTORC1 signaling, phosphorylation of Akt was increased in Pten-ko and decreased in Tsc1-ko neurons, potentially accounting for the different effects on synaptic transmission. Despite the different effects at the synaptic level, our data suggest that loss of Pten or Tsc1 may both lead to an increase in the ratio of excitation to inhibition at the network level, an effect that has been proposed to underlie both epilepsy and autism.

  18. Dysfunctional hippocampal inhibition in the Ts65Dn mouse model of Down syndrome.

    Science.gov (United States)

    Best, Tyler K; Cramer, Nathan P; Chakrabarti, Lina; Haydar, Tarik F; Galdzicki, Zygmunt

    2012-02-01

    GABAergic dysfunction is implicated in hippocampal deficits of the Ts65Dn mouse model of Down syndrome (DS). Since Ts65Dn mice overexpress G-protein coupled inward-rectifying potassium (GIRK2) containing channels, we sought to evaluate whether increased GABAergic function disrupts the functioning of hippocampal circuitry. After confirming that GABA(B)/GIRK current density is significantly elevated in Ts65Dn CA1 pyramidal neurons, we compared monosynaptic inhibitory inputs in CA1 pyramidal neurons in response to proximal (stratum radiatum; SR) and distal (stratum lacunosum moleculare; SLM) stimulation of diploid and Ts65Dn acute hippocampal slices. Synaptic GABA(B) and GABA(A) mediated currents evoked by SR stimulation were generally unaffected in Ts65Dn CA1 neurons. However, the GABA(B)/GABA(A) ratios evoked by stimulation within the SLM of Ts65Dn hippocampus were significantly larger in magnitude, consistent with increased GABA(B)/GIRK currents after SLM stimulation. These results indicate that GIRK overexpression in Ts65Dn has functional consequences which affect the balance between GABA(B) and GABA(A) inhibition of CA1 pyramidal neurons, most likely in a pathway specific manner, and may contribute to cognitive deficits reported in these mice.

  19. Computational modeling of the effects of amyloid-beta on release probability at hippocampal synapses

    Directory of Open Access Journals (Sweden)

    Armando eRomani

    2013-01-01

    Full Text Available The role of amyloid-beta (Aβ in brain function and in the pathogenesis of Alzheimer’s disease remains elusive. Recent publications reported that an increase in Aβ concentration perturbs pre-synaptic release in hippocampal neurons. In particular, it was shown in vitro that Aβ is an endogenous regulator of synaptic transmission at the CA3-CA1 synapse, enhancing its release probability. How this synaptic modulator influences neuronal output during physiological stimulation patterns, such as those elicited in vivo, is still unknown. Using a realistic model of hippocampal CA1 pyramidal neurons, we first implemented this Aβ-induced enhancement of release probability and validated the model by reproducing the experimental findings. We then demonstrated that this synaptic modification can significantly alter synaptic integration properties in a wide range of physiologically relevant input frequencies (from 5 to 200 Hz. Finally, we used natural input patterns, obtained from CA3 pyramidal neurons in vivo during free exploration of rats in an open field, to investigate the effects of enhanced Aβ on synaptic release under physiological conditions. The model shows that the CA1 neuronal response to these natural patterns is altered in the increased-Aβ condition, especially for frequencies in the theta and gamma ranges. These results suggest that the perturbation of release probability induced by increased Aβ can significantly alter the spike probability of CA1 pyramidal neurons and thus contribute to abnormal hippocampal function during Alzheimer’s disease.

  20. Cell type-specific tuning of hippocampal interneuron firing during gamma oscillations in vivo.

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    Tukker, John J; Fuentealba, Pablo; Hartwich, Katja; Somogyi, Peter; Klausberger, Thomas

    2007-08-01

    Cortical gamma oscillations contribute to cognitive processing and are thought to be supported by perisomatic-innervating GABAergic interneurons. We performed extracellular recordings of identified interneurons in the hippocampal CA1 area of anesthetized rats, revealing that the firing patterns of five distinct interneuron types are differentially correlated to spontaneous gamma oscillations. The firing of bistratified cells, which target dendrites of pyramidal cells coaligned with the glutamatergic input from hippocampal area CA3, is strongly phase locked to field gamma oscillations. Parvalbumin-expressing basket, axo-axonic, and cholecystokinin-expressing interneurons exhibit moderate gamma modulation, whereas the spike timing of distal dendrite-innervating oriens-lacunosum moleculare interneurons is not correlated to field gamma oscillations. Cholecystokinin-expressing interneurons fire earliest in the gamma cycle, a finding that is consistent with their suggested function of thresholding individual pyramidal cells. Furthermore, we show that field gamma amplitude correlates with interneuronal spike-timing precision and firing rate. Overall, our recordings suggest that gamma synchronization in vivo is assisted by temporal- and domain-specific GABAergic inputs to pyramidal cells and is initiated in pyramidal cell dendrites in addition to somata and axon initial segments.

  1. Muscarinic receptor activation determines the effects of store-operated Ca(2+)-entry on excitability and energy metabolism in pyramidal neurons.

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    Kann, Oliver; Taubenberger, Nando; Huchzermeyer, Christine; Papageorgiou, Ismini E; Benninger, Felix; Heinemann, Uwe; Kovács, Richard

    2012-01-01

    In various cell types, depletion of intracellular Ca(2+)-stores results in store-operated Ca(2+)-entry (SOCE) across the cellular membrane. However, the effects of SOCE on neuronal membrane excitability and mitochondrial functions in central neurons are not well defined. We investigated such cellular downstream effects in pyramidal neurons of rat organotypic hippocampal slice cultures by applying electrophysiological and fluorescence imaging techniques. We report that SOCE is associated with (i) elevations of Ca(2+)-concentration in individual neuronal mitochondria ([Ca(2+)](m)). In addition, SOCE can result in (ii) hyperpolarizing neuronal membrane currents, (iii) increase in extracellular K(+)-concentration ([K(+)](o)), (iv) mitochondrial membrane depolarization, and (v) changes in intracellular redox state (NAD(P)H and FAD fluorescence), the latter reflecting responses of energy metabolism. These additional downstream effects of SOCE required concomitant muscarinic receptor activation by carbachol or acetylcholine, and were suppressed by agonist washout or application of antagonist, atropine. We conclude that muscarinic receptor activation determines the downstream effects of SOCE on neuronal membrane excitability and energy metabolism. This mechanism might have significant impact on information processing and neurometabolic coupling in central neurons. Copyright © 2011 Elsevier Ltd. All rights reserved.

  2. SDF-1α和CXCR4在低氧缺糖海马脑片中的表达变化%Expressional changes of SDF-1α and CXCR4 proteins in oxygen-glucose deprivation hippocampal organotypic slice culture of rat

    Institute of Scientific and Technical Information of China (English)

    王玉兰; 徐红; 李爱娜

    2011-01-01

    To investigate expressional changes of SDF-1 α and CXCR4 proteins in oxygen-glucose dep-rivation( OGD ) hippocampal slice. Methods Western blot and immunohistochemistry analyses were used to detect SDF-1 α and CXCR4 proteins expression in hippocampal slice of HOTC group and OGD group. Results Immunohistochemistry showed that the SDF-1 α and CXCR4 proteins were expressed in hippocampal slice both HOTC group and OGD group, its hyalomitome was stained, and the CXCR4 protein expression was detected in the axon hillock of pyramidal cells. Western blot results showed that the expressions of SDF-1 α and CXCR4 proteins increased after OGD, and the expression of SDF-1 a proteins had significantly increased( P <0. 01 ). Conclusion The expressional changes of SDF-1 α and CXCR4 proteins indicate that SDF-1 a is associated with the OGD of hippocampal slice.%目的 研究海马脑片低氧缺糖损伤后SDF-1α和CXCR4蛋白的表达变化情况.方法 运用脑片培养技术建立低氧缺糖海马脑片模型,用免疫组化法和Western blot法检测SDF-1α和CXCR4的表达变化.结果 低氧缺糖损伤前后海马脑片中均可见SDF-1α和CXCR4表达的阳性细胞,其胞膜和胞质呈棕黄色着色,其中部分轴丘可见CXCR4阳性蛋白表达.Western blot发现,损伤后在分子量为11 ku和43 ku处分别检测到SDF-1α、CXCR4阳性条带;与正常对照组相比,OGD组SDF-1α和CXCR4表达均增加,其中SDF-1α表达增加差异有统计学意义(P<0.01).结论 海马脑片缺氧缺糖损伤后SDF-1α蛋白表达增加,提示SDF-1α可能与海马脑片低氧缺糖损伤密切相关.

  3. Loss of Functional A-Type Potassium Channels in the Dendrites of CA1 Pyramidal Neurons from a Mouse Model of Fragile X Syndrome

    OpenAIRE

    Routh, Brandy N.; Johnston, Daniel; Brager, Darrin H.

    2013-01-01

    Despite the critical importance of voltage-gated ion channels in neurons, very little is known about their functional properties in Fragile X syndrome: the most common form of inherited cognitive impairment. Using three complementary approaches, we investigated the physiological role of A-type K+ currents (IKA) in hippocampal CA1 pyramidal neurons from fmr1-/y mice. Direct measurement of IKA using cell-attached patch-clamp recordings revealed that there was significantly less IKA in the dendr...

  4. Localization of Brain-Derived Neurotrophic Factor to Distinct Terminals of Mossy Fiber Axons Implies Regulation of Both Excitation and Feedforward Inhibition of CA3 Pyramidal Cells

    OpenAIRE

    Danzer, Steve C.; McNamara, James O.

    2004-01-01

    Hippocampal dentate granule cells directly excite and indirectly inhibit CA3 pyramidal cells via distinct presynaptic terminal specializations of their mossy fiber axons. This mossy fiber pathway contains the highest concentration of brain-derived neurotrophic factor (BDNF) in the CNS, yet whether BDNF is positioned to regulate the excitatory and/or inhibitory pathways is unknown. To localize BDNF, confocal microscopy of green fluorescent protein transgenic mice was combined with BDNF immunoh...

  5. Effect of Pyramidal Dome Geometry on the Acoustical Characteristics in A Mosque

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    Dg. H. Kassim

    2014-12-01

    Full Text Available As an important symbol in Islam, a mosque is built with architectural grandeur. Among the characteristics is its high ceiling and it is usually constructed with a typical spherical dome shape. Some mosques, however, are influenced by the local culture and the dome can be of a different shape, such as pyramidal, as found in mosques in Malacca, Malaysia. This paper presents an assessment of the internal acoustical characteristics of a mosque having a pyramidal dome. The study is conducted by means of computer simulation using CATT indoor acoustic software. Reverberation time and clarity are taken to evaluate the intelligibility of speech. The effect of the angle and height of the dome on the acoustical parameters is discussed. It is found that a pyramidal dome with a steeper angle contributes to poor acoustic clarity.

  6. Neuropeptides and hippocampal neurogenesis.

    Science.gov (United States)

    Zaben, M J; Gray, W P

    2013-12-01

    Hippocampal neurogenesis is important for modulating the behavioural responses to stress and for certain forms of learning and memory. The mechanisms underlying the necessary coupling of neuronal activity to neural stem/progenitor cell (NSPC) function remain poorly understood. Within the dentate subgranular stem cell niche, local interneurons appear to play an important part in this excitation-neurogenesis coupling via GABAergic transmission, which promotes neuronal differentiation and integration. Neuropeptides such as neuropeptide Y (NPY), vasoactive intestinal peptide (VIP) and galanin have emerged as important mediators for signalling local and extrinsic interneuronal activity to subgranular zone precursors. Here we review the distribution of these neuropeptides and their receptors in the neurogenic area of the hippocampus and their precise effects on hippocampal neurogenesis. We also discuss neuropeptides' potential involvement in functional aspects of hippocampal neurogenesis particularly their involvement in the modulation of learning and memory and behavior responses.

  7. The Babinski sign and the pyramidal syndrome.

    Science.gov (United States)

    Van Gijn, J

    1978-10-01

    The presence or absence of a Babinski sign can be puzzling, but in the light of existing pathological studies it is more fruitful to consider which pyramidal tract fibres release it than whether they release it. This was investigated clinically, by looking for correlations with other reflex changes and with motor deficits in the leg. A survey of 50 patients with a unilateral Babinski sign and six patients who lacked it in spite of other pyramidal tract signs was supplemented with follow-up of the patients who had acute lesions. Appearance of the Bibinski sign proved to depend on the interaction of two factors: (1) activity (not necessarily hyperactivity) in the segmental pathways of the flexion synergy; (2) a motor deficit of the foot, in some cases consisting only in an impairment of rapid foot movements, and probably representing a disturbance of direct pyramidal tract projections to distal motoneurones.

  8. D-Serine Is a Substrate for Neutral Amino Acid Transporters ASCT1/SLC1A4 and ASCT2/SLC1A5, and Is Transported by Both Subtypes in Rat Hippocampal Astrocyte Cultures.

    Science.gov (United States)

    Foster, Alan C; Farnsworth, Jill; Lind, Genevieve E; Li, Yong-Xin; Yang, Jia-Ying; Dang, Van; Penjwini, Mahmud; Viswanath, Veena; Staubli, Ursula; Kavanaugh, Michael P

    2016-01-01

    N-methyl-D-aspartate (NMDA) receptors play critical roles in synaptic transmission and plasticity. Activation of NMDA receptors by synaptically released L-glutamate also requires occupancy of co-agonist binding sites in the tetrameric receptor by either glycine or D-serine. Although D-serine appears to be the predominant co-agonist at synaptic NMDA receptors, the transport mechanisms involved in D-serine homeostasis in brain are poorly understood. In this work we show that the SLC1 amino acid transporter family members SLC1A4 (ASCT1) and SLC1A5 (ASCT2) mediate homo- and hetero-exchange of D-serine with physiologically relevant kinetic parameters. In addition, the selectivity profile of D-serine uptake in cultured rat hippocampal astrocytes is consistent with uptake mediated by both ASCT1 and ASCT2. Together these data suggest that SLC1A4 (ASCT1) may represent an important route of Na-dependent D-serine flux in the brain that has the ability to regulate extracellular D-serine and thereby NMDA receptor activity.

  9. D-Serine Is a Substrate for Neutral Amino Acid Transporters ASCT1/SLC1A4 and ASCT2/SLC1A5, and Is Transported by Both Subtypes in Rat Hippocampal Astrocyte Cultures.

    Directory of Open Access Journals (Sweden)

    Alan C Foster

    Full Text Available N-methyl-D-aspartate (NMDA receptors play critical roles in synaptic transmission and plasticity. Activation of NMDA receptors by synaptically released L-glutamate also requires occupancy of co-agonist binding sites in the tetrameric receptor by either glycine or D-serine. Although D-serine appears to be the predominant co-agonist at synaptic NMDA receptors, the transport mechanisms involved in D-serine homeostasis in brain are poorly understood. In this work we show that the SLC1 amino acid transporter family members SLC1A4 (ASCT1 and SLC1A5 (ASCT2 mediate homo- and hetero-exchange of D-serine with physiologically relevant kinetic parameters. In addition, the selectivity profile of D-serine uptake in cultured rat hippocampal astrocytes is consistent with uptake mediated by both ASCT1 and ASCT2. Together these data suggest that SLC1A4 (ASCT1 may represent an important ro