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Sample records for hippocampal neuron number

  1. Preservation of hippocampal neuron numbers in aged rhesus monkeys

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    Keuker, J.I.H.; Luiten, P.G.M.; Fuchs, E.

    2003-01-01

    To investigate whether or not aging of nonhuman primates is accompanied by a region-specific neuron loss in the hippocampal formation, we used the optical fractionator technique to obtain stereological estimates of unilateral neuron numbers of the hippocampi of eight young (0-4 years) and five aged

  2. The effects of bilateral vestibular loss on hippocampal volume, neuronal number and cell proliferation in rats

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    Yiwen eZheng

    2012-02-01

    Full Text Available Previous studies in humans have shown that bilateral loss of vestibular function is associated with a significant bilateral atrophy of the hippocampus, which correlated with the patients’ spatial memory deficits. More recently, patients who had recovered from unilateral vestibular neuritis have been reported to exhibit a significant atrophy of the left posterior hippocampus. Therefore, we investigated whether bilateral vestibular deafferentation (BVD would result in a decrease in neuronal number or volume in the rat hippocampus, using stereological methods. At 16 months post-BVD, we found no significant differences in hippocampal neuronal number or volume compared to sham controls, despite the fact that these animals exhibited severe spatial memory deficits. By contrast, using bromodeoxyuridine (BrdU as a marker of cell proliferation, we found that the number of BrdU-labelled cells significantly increased in the dentate gyrus of the hippocampus between 48 h and 1 week following BVD. Although a substantial proportion of these cells survived for up to 1 month, the survival rate was significantly lower in BVD animals when compared with that in sham animals. These results suggest a dissociation between the effects of BVD on spatial memory and hippocampal structure in rats and humans, which cannot be explained by an injury-induced increase in cell proliferation.

  3. Vitamin C deficiency in early postnatal life impairs spatial memory and reduces the number of hippocampal neurons in guinea pigs

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    Tveden-Nyborg, Pernille Yde; Johansen, Louise Kruse; Raida, Zindy

    2009-01-01

    was assessed by the Morris Water Maze, and hippocampal neuron numbers were quantified by stereologic techniques. RESULTS: The results showed a reduction in spatial memory (P ... in spatial memory in guinea pigs. We speculate that this unrecognized effect of vitamin C deficiency may have clinical implications for high-risk individuals, such as in children born from vitamin C-deficient mothers....

  4. Effects of prolonged abstinence from METH on the hippocampal BDNF levels, neuronal numbers and apoptosis in methamphetamine-sensitized rats.

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    Hajheidari, Samira; Sameni, Hamid Reza; Bandegi, Ahmad Reza; Miladi-Gorji, Hossein

    2017-04-03

    Methamphetamine (METH) use is associated with neuronal damage in various regions of brain, while effects of prolonged abstinence on METH-induced damage are not quite clear. This study evaluated serum and hippocampal BDNF levels, neuronal numbers and apoptosis in METH-sensitized and abstinent rats. Rats were sensitized to METH (2mg/kg, daily/18 days, s.c.). All rats were evaluated for neuron counting, the TUNEL test and serum and hippocampal BDNF levels after 30 days of forced abstinence from METH. The results showed that increased BDNF levels in the hippocampus and serum of METH-sensitized rats returned to control level after 30 days of abstinence. The number of neurons in the DG and CA1 of hippocampus and also, the total hippocampal perimeter and area in METH-sensitized rats were significantly lower than the saline rats. While, the number of neurons was not significantly increased in the hippocampus after prolonged abstinence from METH. Also, METH-sensitized rats showed a significant increase in TUNEL-positive cells, whereas METH-abstinent rats showed a slight but significant decrease in TUNEL-positive cells in the DG and CA3 of hippocampus. These results suggest that despite the reduction in BDNF levels, reducing the number of neurons, perimeter and area of the hippocampus were stable after abstinence. Thus, the degenerative effects of METH have been sustained even after prolonged abstinence in the hippocampus. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Decreased Oligodendrocyte and Neuron Number in Anterior Hippocampal Areas and the Entire Hippocampus in Schizophrenia: A Stereological Postmortem Study.

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    Falkai, Peter; Malchow, Berend; Wetzestein, Katharina; Nowastowski, Verena; Bernstein, Hans-Gert; Steiner, Johann; Schneider-Axmann, Thomas; Kraus, Theo; Hasan, Alkomiet; Bogerts, Bernhard; Schmitz, Christoph; Schmitt, Andrea

    2016-07-01

    The hippocampus is involved in cognition as well as emotion, with deficits in both domains consistently described in schizophrenia. Moreover, the whole volumes of both the anterior and posterior region have been reported to be decreased in schizophrenia patients. While fewer oligodendrocyte numbers in the left and right cornu ammonis CA4 subregion of the posterior part of the hippocampus have been reported, the aim of this stereological study was to investigate cell numbers in either the dentate gyrus (DG) or subregions of the anterior hippocampus. In this design-based stereological study of the anterior part of the hippocampus comparing 10 patients with schizophrenia to 10 age- and gender-matched healthy controls were examined. Patients showed a decreased number of oligodendrocytes in the left CA4, fewer neurons in the left DG and smaller volumes in both the left CA4 and DG, which correlated with oligodendrocyte and neuron numbers, respectively. When exploring the total hippocampus, keeping previously published own results from the posterior part of the same brains in mind, both decreased oligodendrocyte numbers in the left CA4 and reduced volume remained significant. The decreased oligodendrocyte number speaks for a deficit in myelination and connectivity in schizophrenia which may originate from disturbed maturational processes. The reduced neuron number of the DG in the anterior hippocampus may well point to a reduced capacity of this region to produce new neurons up to adulthood. Both mechanisms may be involved in cognitive dysfunction in schizophrenia patients. © The Author 2016. Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  6. Conditional self-discrimination enhances dendritic spine number and dendritic length at prefrontal cortex and hippocampal neurons of rats.

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    Penagos-Corzo, Julio C; Bonilla, Andrea; Rodríguez-Moreno, Antonio; Flores, Gonzalo; Negrete-Díaz, José V

    2015-11-01

    We studied conditional self-discrimination (CSD) in rats and compared the neuronal cytoarchitecture of untrained animals and rats that were trained in self-discrimination. For this purpose, we used thirty 10-week-old male rats were randomized into three groups: one control group and two conditioning groups: a comparison group (associative learning) and an experimental group (self-discrimination). At the end of the conditioning process, the experimental group managed to discriminate their own state of thirst. After the conditioning process, dendritic morphological changes in the pyramidal neurons of the prefrontal cortex and CA1 region of the dorsal hippocampus were evaluated using Golgi-Cox stain method and then analyzed by the Sholl method. Differences were found in total dendritic length and spine density. Animals trained in self-discrimination showed an increase in the dendritic length and the number of dendritic spines of neurons of the prefrontal cortex and CA1 region of the dorsal hippocampus. Our data suggest that conditional self-discrimination improves the connectivity of the prefrontal cortex and dorsal CA1, which has implications for memory and learning processes. © 2015 Wiley Periodicals, Inc.

  7. The Effect of N-acetyl-cysteine on Memory Retrieval and the Number of Intact Neurons of Hippocampal CA1 Area in Streptozotocin-induced Alzheimeric Male Rats

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    Niloufar Darbandi

    2018-01-01

    Full Text Available Abstract Background: Alzheimer is a neurodegenerative disease wich caused memory impairment, reduced cognitive functions, intellectual ability and behavior changes. In this study, the effect of N-acetyl-cysteine (NAC as a strong antioxidant on memory deficiency and number of CA1 pyramidal neurons in Streptozotocine (STZ - induced Alzheimeric rats were studied. Materials and Methods: 32 Male Wistar rats were divided into four groups: sham group, streptozotocin group, treated group with streptozotocin plus N-acetyl-cysteine, and treated group with N-acetyl-cysteine alone. Intracerebroventricular (ICV administration of STZ was done in the first and the third day of surgery and i.p injection of N-acetyl-cysteine was done in the fourth of surgery. After the memory test, the animals were killed and their brains were fixed and density of intact neurons in the CA1 area of the hippocampus was investigated. Statistical analysis was performed with software SPSS, ANOVA and Prisme software. The level of statistical significance was set at p 0.05. Conclusion: N-acetyl-cysteine improved memory retrieval and hippocampal CA1 area intact neurons in streptozotocin-induced Alzheimeric male rats.

  8. Stochastic resonance in hippocampal CA1 neurons

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    Stacey, William Charles

    Stochastic Resonance (SR) is a phenomenon observed in nonlinear systems whereby the introduction of noise enhances the detection of a subthreshold signal for a certain range of noise intensity. Many central neurons, such as hippocampal CAI cells, are good candidates for SR due to their function of signal detection in a noisy environment, but the role of SR in the CNS is unclear. Physiological levels of noise are able to improve signal detection through SR, as found in simulated CAI neurons and in vitro rat hippocampal slices. Further investigation, utilizing a novel method of in vitro noise modulation, shows that endogenous noise sources can generate SR activity. These results suggest SR may provide a means for the hippocampus to modulate detection of specific inputs through endogenous noise sources. The role of noise in signal detection for a network of CAI cells is tested with a network simulation. The network shows improved detection as the number of cells and coupling increase for noise with low variance. One cell receiving the signal cannot recruit the remaining cells unless the network is very active and tuned by the coupling and noise. Periodic oscillations at high noise amplitudes corrupt all outputs. These oscillations develop into synchronized, periodic bursts as a function of both noise and coupling. These findings are relevant for the analysis of the role of physiological noise in signal processing in the brain and in the synchronization of neural activity as in epilepsy.

  9. Dopamine inhibits mitochondrial motility in hippocampal neurons.

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    Sigeng Chen

    2008-07-01

    Full Text Available The trafficking of mitochondria within neurons is a highly regulated process. In an earlier study, we found that serotonin (5-HT, acting through the 5-HT1A receptor subtype, promotes axonal transport of mitochondria in cultured hippocampal neurons by increasing Akt activity, and consequently decreasing glycogen synthase kinase (GSK3beta activity. This finding suggests a critical role for neuromodulators in the regulation of mitochondrial trafficking in neurons. In the present study, we investigate the effects of a second important neuromodulator, dopamine, on mitochondrial transport in hippocampal neurons.Here, we show that dopamine, like 5-HT, regulates mitochondrial motility in cultured hippocampal neurons through the Akt-GSK3beta signaling cascade. But, in contrast to the stimulatory effect of 5-HT, administration of exogenous dopamine or bromocriptine, a dopamine 2 receptor (D2R agonist, caused an inhibition of mitochondrial movement. Moreover, pretreatment with bromocriptine blocked the stimulatory effect of 5-HT on mitochondrial movement. Conversely, in cells pretreated with 5-HT, no further increases in movement were observed after administration of haloperidol, a D2R antagonist. In contrast to the effect of the D2R agonist, addition of SKF38393, a dopamine 1 receptor (D1R agonist, promoted mitochondrial transport, indicating that the inhibitory effect of dopamine was actually the net summation of opposing influences of the two receptor subtypes. The most pronounced effect of dopamine signals was on mitochondria that were already moving directionally. Western blot analysis revealed that treatment with either a D2R agonist or a D1R antagonist decreased Akt activity, and conversely, treatment with either a D2R antagonist or a D1R agonist increased Akt activity.Our observations strongly suggest a role for both dopamine and 5-HT in regulating mitochondrial movement, and indicate that the integrated effects of these two neuromodulators may be

  10. Ischemic Preconditioning Mediates Neuroprotection against Ischemia in Mouse Hippocampal CA1 Neurons by Inducing Autophagy

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    Zhang, Xuebin; Huang, Huiling; Wang, Jin; Wang, Yajing; Tong, Xiaoguang; Wang, Jinhuan; Wu, Jialing

    2015-01-01

    The hippocampal CA1 region is sensitive to hypoxic and ischemic injury but can be protected by ischemic preconditioning (IPC). However, the mechanism through which IPC protects hippocampal CA1 neurons is still under investigation. Additionally, the role of autophagy in determining the fate of hippocampal neurons is unclear. Here, we examined whether IPC induced autophagy to alleviate hippocampal CA1 neuronal death in vitro and in vivo with oxygen glucose deprivation (OGD) and bilateral carotid artery occlusion (BCCAO) models. Survival of hippocampal neurons increased from 51.5% ± 6.3% in the non-IPC group (55 min of OGD) to 77.3% ± 7.9% in the IPC group (15 min of OGD, followed by 55 min of OGD 24 h later). The number of hippocampal CA1 layer neurons increased from 182 ± 26 cells/mm2 in the non-IPC group (20 min of BCCAO) to 278 ± 55 cells/mm2 in the IPC group (1 min × 3 BCCAO, followed by 20 min of BCCAO 24 h later). Akt phosphorylation and microtubule-associated protein light chain 3 (LC3)-II/LC3-I expression were increased in the preconditioning group. Moreover, the protective effects of IPC were abolished only by inhibiting the activity of autophagy, but not by blocking the activation of Akt in vitro. Using in vivo experiments, we found that LC3 expression was upregulated, accompanied by an increase in neuronal survival in hippocampal CA1 neurons in the preconditioning group. The neuroprotective effects of IPC on hippocampal CA1 neurons were completely inhibited by treatment with 3-MA. In contrast, hippocampal CA3 neurons did not show changes in autophagic activity or beneficial effects of IPC. These data suggested that IPC may attenuate ischemic injury in hippocampal CA1 neurons through induction of Akt-independent autophagy. PMID:26325184

  11. Damage of hippocampal neurons in rats with chronic alcoholism

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    Du, Ailin; Jiang, Hongbo; Xu, Lei; An, Na; Liu, Hui; Li, Yinsheng; Zhang, Ruiling

    2014-01-01

    Chronic alcoholism can damage the cytoskeleton and aggravate neurological deficits. However, the effect of chronic alcoholism on hippocampal neurons remains unclear. In this study, a model of chronic alcoholism was established in rats that were fed with 6% alcohol for 42 days. Endogenous hydrogen sulfide content and cystathionine-beta-synthase activity in the hippocampus of rats with chronic alcoholism were significantly increased, while F-actin expression was decreased. Hippocampal neurons i...

  12. Memory formation orchestrates the wiring of adult-born hippocampal neurons into brain circuits.

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    Petsophonsakul, Petnoi; Richetin, Kevin; Andraini, Trinovita; Roybon, Laurent; Rampon, Claire

    2017-08-01

    During memory formation, structural rearrangements of dendritic spines provide a mean to durably modulate synaptic connectivity within neuronal networks. New neurons generated throughout the adult life in the dentate gyrus of the hippocampus contribute to learning and memory. As these neurons become incorporated into the network, they generate huge numbers of new connections that modify hippocampal circuitry and functioning. However, it is yet unclear as to how the dynamic process of memory formation influences their synaptic integration into neuronal circuits. New memories are established according to a multistep process during which new information is first acquired and then consolidated to form a stable memory trace. Upon recall, memory is transiently destabilized and vulnerable to modification. Using contextual fear conditioning, we found that learning was associated with an acceleration of dendritic spines formation of adult-born neurons, and that spine connectivity becomes strengthened after memory consolidation. Moreover, we observed that afferent connectivity onto adult-born neurons is enhanced after memory retrieval, while extinction training induces a change of spine shapes. Together, these findings reveal that the neuronal activity supporting memory processes strongly influences the structural dendritic integration of adult-born neurons into pre-existing neuronal circuits. Such change of afferent connectivity is likely to impact the overall wiring of hippocampal network, and consequently, to regulate hippocampal function.

  13. Trim9 Deletion Alters the Morphogenesis of Developing and Adult-Born Hippocampal Neurons and Impairs Spatial Learning and Memory.

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    Winkle, Cortney C; Olsen, Reid H J; Kim, Hyojin; Moy, Sheryl S; Song, Juan; Gupton, Stephanie L

    2016-05-04

    During hippocampal development, newly born neurons migrate to appropriate destinations, extend axons, and ramify dendritic arbors to establish functional circuitry. These developmental stages are recapitulated in the dentate gyrus of the adult hippocampus, where neurons are continuously generated and subsequently incorporate into existing, local circuitry. Here we demonstrate that the E3 ubiquitin ligase TRIM9 regulates these developmental stages in embryonic and adult-born mouse hippocampal neurons in vitro and in vivo Embryonic hippocampal and adult-born dentate granule neurons lacking Trim9 exhibit several morphological defects, including excessive dendritic arborization. Although gross anatomy of the hippocampus was not detectably altered by Trim9 deletion, a significant number of Trim9(-/-) adult-born dentate neurons localized inappropriately. These morphological and localization defects of hippocampal neurons in Trim9(-/-) mice were associated with extreme deficits in spatial learning and memory, suggesting that TRIM9-directed neuronal morphogenesis may be involved in hippocampal-dependent behaviors. Appropriate generation and incorporation of adult-born neurons in the dentate gyrus are critical for spatial learning and memory and other hippocampal functions. Here we identify the brain-enriched E3 ubiquitin ligase TRIM9 as a novel regulator of embryonic and adult hippocampal neuron shape acquisition and hippocampal-dependent behaviors. Genetic deletion of Trim9 elevated dendritic arborization of hippocampal neurons in vitro and in vivo Adult-born dentate granule cells lacking Trim9 similarly exhibited excessive dendritic arborization and mislocalization of cell bodies in vivo These cellular defects were associated with severe deficits in spatial learning and memory. Copyright © 2016 the authors 0270-6474/16/364940-19$15.00/0.

  14. Astrocyte calcium signalling orchestrates neuronal synchronization in organotypic hippocampal slices

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    Sasaki, Takuya; Ishikawa, Tomoe; Abe, Reimi; Nakayama, Ryota; Asada, Akiko; Matsuki, Norio; Ikegaya, Yuji

    2014-01-01

    Astrocytes are thought to detect neuronal activity in the form of intracellular calcium elevations; thereby, astrocytes can regulate neuronal excitability and synaptic transmission. Little is known, however, about how the astrocyte calcium signal regulates the activity of neuronal populations. In this study, we addressed this issue using functional multineuron calcium imaging in hippocampal slice cultures. Under normal conditions, CA3 neuronal networks exhibited temporally correlated activity patterns, occasionally generating large synchronization among a subset of cells. The synchronized neuronal activity was correlated with astrocyte calcium events. Calcium buffering by an intracellular injection of a calcium chelator into multiple astrocytes reduced the synaptic strength of unitary transmission between pairs of surrounding pyramidal cells and caused desynchronization of the neuronal networks. Uncaging the calcium in the astrocytes increased the frequency of neuronal synchronization. These data suggest an essential role of the astrocyte calcium signal in the maintenance of basal neuronal function at the circuit level. PMID:24710057

  15. Intervention effects of ganoderma lucidum spores on epileptiform discharge hippocampal neurons and expression of neurotrophin-4 and N-cadherin.

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    Shu-Qiu Wang

    Full Text Available Epilepsy can cause cerebral transient dysfunctions. Ganoderma lucidum spores (GLS, a traditional Chinese medicinal herb, has shown some antiepileptic effects in our previous studies. This was the first study of the effects of GLS on cultured primary hippocampal neurons, treated with Mg(2+ free medium. This in vitro model of epileptiform discharge hippocampal neurons allowed us to investigate the anti-epileptic effects and mechanism of GLS activity. Primary hippocampal neurons from <1 day old rats were cultured and their morphologies observed under fluorescence microscope. Neurons were confirmed by immunofluorescent staining of neuron specific enolase (NSE. Sterile method for GLS generation was investigated and serial dilutions of GLS were used to test the maximum non-toxic concentration of GLS on hippocampal neurons. The optimized concentration of GLS of 0.122 mg/ml was identified and used for subsequent analysis. Using the in vitro model, hippocampal neurons were divided into 4 groups for subsequent treatment i control, ii model (incubated with Mg(2+ free medium for 3 hours, iii GLS group I (incubated with Mg(2+ free medium containing GLS for 3 hours and replaced with normal medium and incubated for 6 hours and iv GLS group II (neurons incubated with Mg(2+ free medium for 3 hours then replaced with a normal medium containing GLS for 6 hours. Neurotrophin-4 and N-Cadherin protein expression were detected using Western blot. The results showed that the number of normal hippocampal neurons increased and the morphologies of hippocampal neurons were well preserved after GLS treatment. Furthermore, the expression of neurotrophin-4 was significantly increased while the expression of N-Cadherin was decreased in the GLS treated group compared with the model group. This data indicates that GLS may protect hippocampal neurons by promoting neurotrophin-4 expression and inhibiting N-Cadherin expression.

  16. Single-cell axotomy of cultured hippocampal neurons integrated in neuronal circuits.

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    Gomis-Rüth, Susana; Stiess, Michael; Wierenga, Corette J; Meyn, Liane; Bradke, Frank

    2014-05-01

    An understanding of the molecular mechanisms of axon regeneration after injury is key for the development of potential therapies. Single-cell axotomy of dissociated neurons enables the study of the intrinsic regenerative capacities of injured axons. This protocol describes how to perform single-cell axotomy on dissociated hippocampal neurons containing synapses. Furthermore, to axotomize hippocampal neurons integrated in neuronal circuits, we describe how to set up coculture with a few fluorescently labeled neurons. This approach allows axotomy of single cells in a complex neuronal network and the observation of morphological and molecular changes during axon regeneration. Thus, single-cell axotomy of mature neurons is a valuable tool for gaining insights into cell intrinsic axon regeneration and the plasticity of neuronal polarity of mature neurons. Dissociation of the hippocampus and plating of hippocampal neurons takes ∼2 h. Neurons are then left to grow for 2 weeks, during which time they integrate into neuronal circuits. Subsequent axotomy takes 10 min per neuron and further imaging takes 10 min per neuron.

  17. Necroptosis Mediates TNF-Induced Toxicity of Hippocampal Neurons

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    Shan Liu

    2014-01-01

    Full Text Available Tumor necrosis factor-α (TNF-α is a critical proinflammatory cytokine regulating neuroinflammation. Elevated levels of TNF-α have been associated with various neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease. However, the signaling events that lead to TNF-α-initiated neurotoxicity are still unclear. Here, we report that RIP3-mediated necroptosis, a form of regulated necrosis, is activated in the mouse hippocampus after intracerebroventricular injection of TNF-α. RIP3 deficiency attenuates TNF-α-initiated loss of hippocampal neurons. Furthermore, we characterized the molecular mechanism of TNF-α-induced neurotoxicity in HT-22 hippocampal neuronal cells. HT-22 cells are sensitive to TNF-α only upon caspase blockage and subsequently undergo necrosis. The cell death is suppressed by knockdown of CYLD or RIP1 or RIP3 or MLKL, suggesting that this necrosis is necroptosis and mediated by CYLD-RIP1-RIP3-MLKL signaling pathway. TNF-α-induced necroptosis of HT-22 cells is largely independent of both ROS accumulation and calcium influx although these events have been shown to be critical for necroptosis in certain cell lines. Taken together, these data not only provide the first in vivo evidence for a role of RIP3 in TNF-α-induced toxicity of hippocampal neurons, but also demonstrate that TNF-α promotes CYLD-RIP1-RIP3-MLKL-mediated necroptosis of hippocampal neurons largely bypassing ROS accumulation and calcium influx.

  18. Exercise preconditioning exhibits neuroprotective effects on hippocampal CA1 neuronal damage after cerebral ischemia

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    Nabi Shamsaei

    2015-01-01

    Full Text Available Recent evidence has suggested the neuroprotective effects of physical exercise on cerebral ischemic injury. However, the role of physical exercise in cerebral ischemia-induced hippocampal damage remains controversial. The aim of the present study was to evaluate the effects of pre-ischemia treadmill training on hippocampal CA1 neuronal damage after cerebral ischemia. Male adult rats were randomly divided into control, ischemia and exercise + ischemia groups. In the exercise + ischemia group, rats were subjected to running on a treadmill in a designated time schedule (5 days per week for 4 weeks. Then rats underwent cerebral ischemia induction through occlusion of common carotids followed by reperfusion. At 4 days after cerebral ischemia, rat learning and memory abilities were evaluated using passive avoidance memory test and rat hippocampal neuronal damage was detected using Nissl and TUNEL staining. Pre-ischemic exercise significantly reduced the number of TUNEL-positive cells and necrotic cell death in the hippocampal CA1 region as compared to the ischemia group. Moreover, pre-ischemic exercise significantly prevented ischemia-induced memory dysfunction. Pre-ischemic exercise mighct prevent memory deficits after cerebral ischemia through rescuing hippocampal CA1 neurons from ischemia-induced degeneration.

  19. Hippocampal neuron populations are reduced in vervet monkeys with fetal alcohol exposure

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    Burke, Mark W; Ptito, Maurice; Ervin, Frank R

    2015-01-01

    of pregnancy. Here, we report significant numerical reductions in the principal hippocampal neurons of fetal alcohol-exposed (FAE) offspring, as compared to age-matched, similarly housed conspecifics with isocaloric sucrose exposure. These deficits, particularly marked in CA1 and CA3, are present neonatally...... late pregnancy results in a stable loss of hippocampal neurons and a progressive reduction of hippocampal volume....

  20. Role of cyclins in neuronal differentiation of immortalized hippocampal cells.

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    Xiong, W; Pestell, R; Rosner, M R

    1997-01-01

    The proto-oncogene cyclin D1 and the neuron-specific cyclins p35 and p39 are expressed during brain maturation. To investigate the role of these cyclins in neuronal differentiation, we used a conditionally immortalized rat hippocampal cell line, H19-7, that expresses cyclin-dependent kinases 4 and 5 (cdk4 and -5). Cyclin D1, which activates cdk4 and binds but does not activate cdk5, was increased upon differentiation of the H19-7 cells. However, microinjection of either sense or antisense cyc...

  1. Young adult born neurons enhance hippocampal dependent performance via influences on bilateral networks

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    Zhuo, Jia-Min; Tseng, Hua-an; Desai, Mitul; Bucklin, Mark E; Mohammed, Ali I.; Robinson, Nick TM; Boyden, Edward S.; Rangel, Lara M; Jasanoff, Alan P; Gritton, Howard J.; Han, Xue

    2016-01-01

    Adult neurogenesis supports performance in many hippocampal dependent tasks. Considering the small number of adult-born neurons generated at any given time, it is surprising that this sparse population of cells can substantially influence behavior. Recent studies have demonstrated that heightened excitability and plasticity may be critical for the contribution of young adult-born cells for certain tasks. What is not well understood is how these unique biophysical and synaptic properties may t...

  2. Synergistic stress exacerbation in hippocampal neurons: Evidence favoring the dual-hit hypothesis of neurodegeneration.

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    Heinemann, Scott D; Posimo, Jessica M; Mason, Daniel M; Hutchison, Daniel F; Leak, Rehana K

    2016-08-01

    The dual-hit hypothesis of neurodegeneration states that severe stress sensitizes vulnerable cells to subsequent challenges so that the two hits are synergistic in their toxic effects. Although the hippocampus is vulnerable to a number of neurodegenerative disorders, there are no models of synergistic cell death in hippocampal neurons in response to combined proteotoxic and oxidative stressors, the two major characteristics of these diseases. Therefore, a relatively high-throughput dual-hit model of stress synergy was developed in primary hippocampal neurons. In order to increase the rigor of the study and strengthen the interpretations, three independent, unbiased viability assays were employed at multiple timepoints. Stress synergy was elicited when hippocampal neurons were treated with the proteasome inhibitor MG132 followed by exposure to the oxidative toxicant paraquat, but only after 48 h. MG132 and paraquat only elicited additive effects 24 h after the final hit and even loss of heat shock protein 70 activity and glutathione did not promote stress synergy at this early timepoint. Dual hits of MG132 elicited modest glutathione loss and slightly synergistic toxic effects 48 h after the second hit, but only at some concentrations and only according to two viability assays (metabolic fitness and cytoskeletal integrity). The thiol N-acetyl cysteine protected hippocampal neurons against dual MG132/MG132 hits but not dual MG132/paraquat hits. These findings support the view that proteotoxic and oxidative stress propel and propagate each other in hippocampal neurons, leading to synergistically toxic effects, but not as the default response and only after a delay. The neuronal stress synergy observed here lies in contrast to astrocytic responses to dual hits, because astrocytes that survive severe proteotoxic stress resist additional cell loss following second hits. In conclusion, a new model of hippocampal vulnerability was developed for the testing of therapies

  3. Differential expression of alpha-synuclein in hippocampal neurons.

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    Katsutoshi Taguchi

    Full Text Available α-Synuclein is the major pathological component of synucleinopathies including Parkinson's disease and dementia with Lewy bodies. Recent studies have demonstrated that α-synuclein also plays important roles in the release of synaptic vesicles and synaptic membrane recycling in healthy neurons. However, the precise relationship between the pathogenicity and physiological functions of α-synuclein remains to be elucidated. To address this issue, we investigated the subcellular localization of α-synuclein in normal and pathological conditions using primary mouse hippocampal neuronal cultures. While some neurons expressed high levels of α-synuclein in presynaptic boutons and cell bodies, other neurons either did not or only very weakly expressed the protein. These α-synuclein-negative cells were identified as inhibitory neurons by immunostaining with specific antibodies against glutamic acid decarboxylase (GAD, parvalbumin, and somatostatin. In contrast, α-synuclein-positive synapses were colocalized with the excitatory synapse marker vesicular glutamate transporter-1. This expression profile of α-synuclein was conserved in the hippocampus in vivo. In addition, we found that while presynaptic α-synuclein colocalizes with synapsin, a marker of presynaptic vesicles, it is not essential for activity-dependent membrane recycling induced by high potassium treatment. Exogenous supply of preformed fibrils generated by recombinant α-synuclein was shown to promote the formation of Lewy body (LB -like intracellular aggregates involving endogenous α-synuclein. GAD-positive neurons did not form LB-like aggregates following treatment with preformed fibrils, however, exogenous expression of human α-synuclein allowed intracellular aggregate formation in these cells. These results suggest the presence of a different mechanism for regulation of the expression of α-synuclein between excitatory and inhibitory neurons. Furthermore, α-synuclein expression

  4. Aluminum in hippocampal neurons from humans with Alzheimer's disease.

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    Walton, J R

    2006-05-01

    Using a staining technique developed in 2004, we examined hippocampal tissue from autopsy-confirmed cases of Alzheimer's disease (AD) and controls. The stain disclosed aluminum in cells and subcellular structure. All pyramidal neurons in these aged specimens appeared to exhibit at least some degree of aluminum staining. Many displayed visible aluminum only in their nucleolus. At the other extreme were neurons that stained for aluminum throughout their nucleus and cytoplasm. The remainder exhibited intermediate degrees of staining. On the basis of their aluminum staining patterns, all pyramidal neurons could be classified into stages that indicated two distinct neuropathological processes, either (1) progressive increase of nuclear aluminum (often accompanied by granulovacuolar degeneration with granules that stain for aluminum) or (2) formation of neurofibrillary tangles (NFTs) in regions of aluminum-rich cytoplasm, especially in AD brain tissue. In the latter process, intraneuronal NFTs appeared to displace nuclei and then enucleate the affected neurons during the course of their transformation into extracellular NFTs. Given that the NFTs we observed in human neurons always developed in conjunction with cytoplasmic aluminum, we hypothesize that aluminum plays an important role in their formation and should therefore be reconsidered as a causative factor for AD.

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

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    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…

  6. Dietary cholesterol modulates the excitability of rabbit hippocampal CA1 pyramidal neurons

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    Wang, Desheng; Schreurs, Bernard G.

    2010-01-01

    Previous work has shown high dietary cholesterol can affect learning and memory including rabbit eyeblink conditioning and this effect may be due to increased membrane cholesterol and enhanced hippocampal amyloid beta production. This study investigated whether dietary cholesterol modulates rabbit hippocampal CA1 neuron membrane properties known to be involved in rabbit eyeblink conditioning. Whole-cell current clamp recordings in hippocampal neurons from rabbits fed 2% cholesterol or normal ...

  7. Electroconvulsive stimulation results in long-term survival of newly generated hippocampal neurons in rats

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    Olesen, Mikkel Vestergaard; Wörtwein, Gitta; Folke, Jonas

    2017-01-01

    of the previous work aiming to test the hypothesis that rats subjected to ECS in combination with chronic restraint stress (CRS) display increased formation of new hippocampal neurons, which have a potential for long-term survival. Furthermore, using mediation analysis, we tested if an ECS-induced increase......U-positive neurons showed time-dependent attrition of ∼40% from day 1 to 3 months, with no further decline between 3 and 12 months. ECS did not affect the number of pre-existing dentate granule neurons or the volume of the dentate granule cell layer, suggesting no damaging effect of the treatment. Finally, we found...... that, while ECS increases neurogenesis, this formation of new neurons was not associated to ameliorated immobility in the FST. This implies that other ECS-induced effects than neurogenesis must be part of mediating the antidepressant action of ECS. Taken together, the results of the present study...

  8. Young adult born neurons enhance hippocampal dependent performance via influences on bilateral networks.

    Science.gov (United States)

    Zhuo, Jia-Min; Tseng, Hua-An; Desai, Mitul; Bucklin, Mark E; Mohammed, Ali I; Robinson, Nick Tm; Boyden, Edward S; Rangel, Lara M; Jasanoff, Alan P; Gritton, Howard J; Han, Xue

    2016-12-03

    Adult neurogenesis supports performance in many hippocampal dependent tasks. Considering the small number of adult-born neurons generated at any given time, it is surprising that this sparse population of cells can substantially influence behavior. Recent studies have demonstrated that heightened excitability and plasticity may be critical for the contribution of young adult-born cells for certain tasks. What is not well understood is how these unique biophysical and synaptic properties may translate to networks that support behavioral function. Here we employed a location discrimination task in mice while using optogenetics to transiently silence adult-born neurons at different ages. We discovered that adult-born neurons promote location discrimination during early stages of development but only if they undergo maturation during task acquisition. Silencing of young adult-born neurons also produced changes extending to the contralateral hippocampus, detectable by both electrophysiology and fMRI measurements, suggesting young neurons may modulate location discrimination through influences on bilateral hippocampal networks.

  9. Mechanism of PAMAM Dendrimers Internalization in Hippocampal Neurons.

    Science.gov (United States)

    Vidal, Felipe; Vásquez, Pilar; Díaz, Carola; Nova, Daniela; Alderete, Joel; Guzmán, Leonardo

    2016-10-03

    Polyamidoamine (PAMAM) dendrimers are hyperbranched macromolecules which have been described as one of the most promising drug nanocarrier systems. A key process to understand is their cellular internalization mechanism because of its direct influence on their intracellular distribution, association with organelles, entry kinetics, and cargo release. Despite that internalization mechanisms of dendrimers have been studied in different cell types, in the case of neurons they are not completely described. Considering the relevance of central nervous system (CNS) diseases and neuropharmacology, the aim of this report is to describe the molecular internalization mechanism of different PAMAM-based dendrimer systems in hippocampal neurons. Four dendrimers based on fourth generation PAMAM with different surface properties were studied: unmodified G4, with a positively charged surface; PP50, with a substitution of the 50% of amino surface groups with polyethylene glycol neutral groups; PAc, with a substitution of the 30% of amino surface groups with acrylate anionic groups; and PFO, decorated with folic acid groups in a 25% of total terminal groups. Confocal images show that both G4 and PFO are able to enter the neurons, but not PP50 and PAc. Colocalization study with specific endocytosis markers and specific endocytosis inhibitor assay demonstrate that clathrin-mediated endocytosis would be the main internalization mechanism for G4, whereas clathrin- and caveolae-mediated endocytosis would be implicated in PFO internalization. These results show the existence of different internalization mechanisms for PAMAM dendrimers in neurons and the possibility to control their internalization properties with specific chemical modifications.

  10. Reverse stochastic resonance in a hippocampal CA1 neuron model.

    Science.gov (United States)

    Durand, Dominique M; Kawaguchi, Minato; Mino, Hiroyuki

    2013-01-01

    Stochastic resonance (SR) is a ubiquitous and counter- intuitive phenomenon whereby the addition of noise to a non-linear system can improve the detection of sub-threshold signals. The "signal" is normally periodic or deterministic whereas the "noise" is normally stochastic. However, in neural systems, signals are often stochastic. Moreover, periodic signals are applied near neurons to control neural excitability (i.e. deep brain stimulation). We therefore tested the hypothesis that a quasi-periodic signal applied to a neural network could enhance the detection of a stochastic neural signal (reverse stochastic resonance). Using computational methods, a CA1 hippocampal neuron was simulated and a Poisson distributed subthreshold synaptic input ("signal") was applied to the synaptic terminals. A periodic or quasi periodic pulse train at various frequencies ("noise") was applied to an extracellular electrode located near the neuron. The mutual information and information transfer rate between the output and input of the neuron were calculated. The results display the signature of stochastic resonance with information transfer reaching a maximum value for increasing power (or frequency) of the "noise". This result shows that periodic signals applied extracellularly can improve the detection of subthreshold stochastic neural signals. The optimum frequency (110 Hz) is similar to that used in patients with Parkinson's suggesting that this phenomenon could play a role in the therapeutic effect of high frequency stimulation.

  11. Design-based estimation of neuronal number and individual neuronal volume in the rat hippocampus

    DEFF Research Database (Denmark)

    Hosseini-Sharifabad, Mohammad; Nyengaard, Jens Randel

    2007-01-01

    Tools recently developed in stereology were employed for unbiased estimation of the neuronal number and volume in three major subdivisions of rat hippocampus (dentate granular, CA1 and CA3 pyramidal layers). The optical fractionator is used extensively in quantitative studies of the hippocampus......; however, the classical optical fractionator design may be affected by tissue deformation in the z-axis of the section. In this study, we applied an improved optical fractionator design to estimate total number of neurons on 100 microm thick vibratome sections that had been deformed, in the z...... vertical sections from the hippocampus. The volume of hippocampal neurons was estimated using the rotator principle on 40 microm thick plastic vertical uniform random sections and corrected for tissue shrinkage. Application of the proposed new design should result in more accurate estimates of neuron...

  12. Temporal expression of neuronal connexins during hippocampal ontogeny.

    Science.gov (United States)

    Rozental, R; Srinivas, M; Gökhan, S; Urban, M; Dermietzel, R; Kessler, J A; Spray, D C; Mehler, M F

    2000-04-01

    Communication through gap junction channels provides a major signaling mechanism during early brain histogenesis, a developmental time during which neural progenitor cells are inexcitable and do not express ligand-gated channel responses to the major CNS neurotransmitters. Expression of different gap junction types during neurogenesis may therefore define intercellular pathways for transmission of developmentally relevant molecules. To better understand the molecular mechanism(s) by which growth and differentiation of neurons are modulated by gap junction channels, we have been examining the developmental effects of a specific set of cytokines on differentiation and gap junction expression in a conditionally immortalized mouse embryonic hippocampal neuronal progenitor cell line (MK31). When multipotent MK31 cells are in an uncommitted state, they uniformly express the neuroepithelial intermediate filament class VI marker, nestin, are strongly coupled by gap junctions composed of connexin43 (Cx43) and express connexin45 (Cx45) at the mRNA level. As these cells undergo neuronal lineage commitment and exit from cell cycle, they begin to express the early neurofilament marker, NF66, and coupling strength and expression of Cx43 begin to decline with concurrent expression of other connexin proteins, including Cx26, Cx33, Cx36, Cx40 and Cx45. Terminal neuronal differentiation is heralded by the expression of more advanced neurofilament proteins, increased morphologic maturation, the elaboration of inward currents and action potentials that possess mature physiological properties, and changing profiles of expression of connexin subtypes, including upregulation of Cx36 expression. These important developmental transitions are regulated by a complex network of cell cycle checkpoints. To begin to examine the precise roles of gap junction proteins in traversing these developmental checkpoints and in thus regulating neurogenesis, we have focused on individual members of two

  13. Specific responses of human hippocampal neurons are associated with better memory.

    Science.gov (United States)

    Suthana, Nanthia A; Parikshak, Neelroop N; Ekstrom, Arne D; Ison, Matias J; Knowlton, Barbara J; Bookheimer, Susan Y; Fried, Itzhak

    2015-08-18

    A population of human hippocampal neurons has shown responses to individual concepts (e.g., Jennifer Aniston) that generalize to different instances of the concept. However, recordings from the rodent hippocampus suggest an important function of these neurons is their ability to discriminate overlapping representations, or pattern separate, a process that may facilitate discrimination of similar events for successful memory. In the current study, we explored whether human hippocampal neurons can also demonstrate the ability to discriminate between overlapping representations and whether this selectivity could be directly related to memory performance. We show that among medial temporal lobe (MTL) neurons, certain populations of neurons are selective for a previously studied (target) image in that they show a significant decrease in firing rate to very similar (lure) images. We found that a greater proportion of these neurons can be found in the hippocampus compared with other MTL regions, and that memory for individual items is correlated to the degree of selectivity of hippocampal neurons responsive to those items. Moreover, a greater proportion of hippocampal neurons showed selective firing for target images in good compared with poor performers, with overall memory performance correlated with hippocampal selectivity. In contrast, selectivity in other MTL regions was not associated with memory performance. These findings show that a substantial proportion of human hippocampal neurons encode specific memories that support the discrimination of overlapping representations. These results also provide previously unidentified evidence consistent with a unique role of the human hippocampus in orthogonalization of representations in declarative memory.

  14. The BDNF val-66-met Polymorphism Affects Neuronal Morphology and Synaptic Transmission in Cultured Hippocampal Neurons from Rett Syndrome Mice

    Directory of Open Access Journals (Sweden)

    Xin Xu

    2017-07-01

    Full Text Available Brain-derived neurotrophic factor (Bdnf has been implicated in several neurological disorders including Rett syndrome (RTT, an X-linked neurodevelopmental disorder caused by loss-of-function mutations in the transcriptional modulator methyl-CpG-binding protein 2 (MECP2. The human BDNF gene has a single nucleotide polymorphism (SNP—a methionine (met substitution for valine (val at codon 66—that affects BDNF’s trafficking and activity-dependent release and results in cognitive dysfunction. Humans that are carriers of the met-BDNF allele have subclinical memory deficits and reduced hippocampal volume and activation. It is still unclear whether this BDNF SNP affects the clinical outcome of RTT individuals. To evaluate whether this BDNF SNP contributes to RTT pathophysiology, we examined the consequences of expression of either val-BDNF or met-BDNF on dendrite and dendritic spine morphology, and synaptic function in cultured hippocampal neurons from wildtype (WT and Mecp2 knockout (KO mice. Our findings revealed that met-BDNF does not increase dendritic growth and branching, dendritic spine density and individual spine volume, and the number of excitatory synapses in WT neurons, as val-BDNF does. Furthermore, met-BDNF reduces dendritic complexity, dendritic spine volume and quantal excitatory synaptic transmission in Mecp2 KO neurons. These results suggest that the val-BDNF variant contributes to RTT pathophysiology, and that BDNF-based therapies should take into consideration the BDNF genotype of the RTT individuals.

  15. Frizzled-5 receptor is involved in neuronal polarity and morphogenesis of hippocampal neurons.

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    Paula G Slater

    Full Text Available The Wnt signaling pathway plays important roles during different stages of neuronal development, including neuronal polarization and dendritic and axonal outgrowth. However, little is known about the identity of the Frizzled receptors mediating these processes. In the present study, we investigated the role of Frizzled-5 (Fzd5 on neuronal development in cultured Sprague-Dawley rat hippocampal neurons. We found that Fzd5 is expressed early in cultured neurons on actin-rich structures localized at minor neurites and axonal growth cones. At 4 DIV, Fzd5 polarizes towards the axon, where its expression is detected mainly at the peripheral zone of axonal growth cones, with no obvious staining at dendrites; suggesting a role of Fzd5 in neuronal polarization. Overexpression of Fzd5 during the acquisition of neuronal polarity induces mislocalization of the receptor and a loss of polarized axonal markers. Fzd5 knock-down leads to loss of axonal proteins, suggesting an impaired neuronal polarity. In contrast, overexpression of Fzd5 in neurons that are already polarized did not alter polarity, but decreased the total length of axons and increased total dendrite length and arborization. Fzd5 activated JNK in HEK293 cells and the effects triggered by Fzd5 overexpression in neurons were partially prevented by inhibition of JNK, suggesting that a non-canonical Wnt signaling mechanism might be involved. Our results suggest that, Fzd5 has a role in the establishment of neuronal polarity, and in the morphogenesis of neuronal processes, in part through the activation of the non-canonical Wnt mechanism involving JNK.

  16. Enhanced dendritic morphogenesis of adult hippocampal newborn neurons in central 5-HT-deficient mice

    Directory of Open Access Journals (Sweden)

    Ning-Ning Song

    2017-03-01

    Full Text Available Serotonin (5-HT plays an important role in regulating adult hippocampal neurogenesis. Chronic administration of selective 5-HT reuptake inhibitors (SSRIs, which up-regulates extracellular 5-HT concentration, accelerates the maturation of adult-born hippocampal neurons. It is unknown, however, about effects of central 5-HT-deficiency on the dendritic morphogenesis of these newborn neurons. Here, we address this question using two central 5-HT-deficient mouse models, Tph2 conditional knockout mice (CKO losing central 5-HT from embryonic stage, and Pet1-Cre;Rosa26-DTR (diphtheria toxin receptor mice lacking central 5-HT neurons exclusively in adulthood. The dendritic length of hippocampal newborn neurons is dramatically increased in these mice. Our findings indicate that reducing central 5-HT can accelerate the dendritic maturation of adult-born neurons, thus revealing a new role of central 5-HT in regulating adult hippocampal neurogenesis.

  17. Study of the protective effects of nootropic agents against neuronal damage induced by amyloid-beta (fragment 25-35) in cultured hippocampal neurons.

    Science.gov (United States)

    Sendrowski, Krzysztof; Sobaniec, Wojciech; Stasiak-Barmuta, Anna; Sobaniec, Piotr; Popko, Janusz

    2015-04-01

    Alzheimer's disease (AD) is a common neurodegenerative disorder, in which progressive neuron loss, mainly in the hippocampus, is observed. The critical events in the pathogenesis of AD are associated with accumulation of β-amyloid (Aβ) peptides in the brain. Deposits of Aβ initiate a neurotoxic "cascade" leading to apoptotic death of neurons. Aim of this study was to assess a putative neuroprotective effects of two nootropic drugs: piracetam (PIR) and levetiracetam (LEV) on Aβ-injured hippocampal neurons in culture. Primary cultures of rat's hippocampal neurons at 7 day in vitro were exposed to Aβ(25-35) in the presence or absence of nootropics in varied concentrations. Flow cytometry with Annexin V/PI staining was used for counting and establishing neurons as viable, necrotic or apoptotic. Additionally, release of lactate dehydrogenase (LDH) to the culture medium, as a marker of cell death, was evaluated. Aβ(25-35) caused concentration-dependent death of about one third number of hippocampal neurons, mainly through an apoptotic pathway. In drugs-containing cultures, number of neurons injured with 20 μM Aβ(25-35) was about one-third lesser for PIR and almost two-fold lesser for LEV. When 40 μM Aβ(25-35) was used, only LEV exerted beneficial neuroprotective action, while PIR was ineffective. Our results suggest the protective potential of both studied nootropics against Aβ-induced death of cultured hippocampal neurons with more powerful neuroprotective effects of LEV. Copyright © 2014 Institute of Pharmacology, Polish Academy of Sciences. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved.

  18. Effect of gestational ethanol exposure on parvalbumin and calretinin expressing hippocampal neurons in a chick model of fetal alcohol syndrome.

    Science.gov (United States)

    Marshall, Audrey G; McCarthy, Molly M; Brishnehan, Kirk M; Rao, Venugopal; Batia, Lyn M; Gupta, Madhul; Das, Srijit; Mitra, Nilesh K; Chaudhuri, Joydeep D

    2009-03-01

    Fetal alcohol syndrome (FAS), a condition occurring in some children of mothers who have consumed alcohol during pregnancy, is characterized by physical deformities and learning and memory deficits. The chick hippocampus, whose functions are controlled by interneurons expressing calcium-binding proteins parvalbumin (PV) and calretinin (CR), is involved in learning and memory mechanisms. Effects on growth and development and hippocampal morphology were studied in chick embryos exposed to 5% and 10% ethanol volume/volume (vol/vol) for 2 or 8 days of gestation. There was a significant dose-dependent reduction (P<.05) in body weight and mean number per section of PV and CR expressing hippocampal neurons in ethanol-exposed chicks, without alterations in neuronal nuclear size or hippocampal volume, compared appropriate controls. Moreover, when chicks exposed to 5% ethanol for 2 and 8 days of gestation were compared, no significant differences were found in body parameters or neuronal counts. Similarly, exposure to 10% ethanol did not induce any significant changes in chicks exposed for 2 or 8 gestational days. Thus, these results suggest that gestational ethanol exposure induces a reduction in the mean number per section of PV and CR expressing hippocampal neurons, and could be a possible mechanism responsible for learning and memory disorders in FAS.

  19. RPTPalpha is required for rigidity-dependent inhibition of extension and differentiation of hippocampal neurons

    DEFF Research Database (Denmark)

    Kostic, Ana; Sap, Jan; Sheetz, Michael P

    2007-01-01

    Receptor-like protein tyrosine phosphatase alpha (RPTPalpha)-knockout mice have severe hippocampal abnormalities similar to knockouts of the Src family kinase Fyn. These enzymes are linked to the matrix-rigidity response in fibroblasts, but their function in neurons is unknown. The matrix...... response in hippocampal neuron growth cones, like in fibroblasts. In control neurons, rigid FN surfaces inhibit neurite extension and neuron differentiation relative to soft surfaces. In RPTPalpha(-/-) neurons, no inhibition of extension and differentiation is found on both rigid and soft surfaces...

  20. Ablation of NMDA receptors enhances the excitability of hippocampal CA3 neurons.

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    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.

  1. Cytomorphometric changes in hippocampal CA1 neurons exposed to simulated microgravity using rats as model

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    Amit eRanjan

    2014-05-01

    Full Text Available Microgravity and sleep loss lead to cognitive and learning deficits. These behavioral alterations are likely to be associated with cytomorphological changes and loss of neurons. To understand the phenomenon, we exposed rats (225-275g to 14 days simulated microgravity (SMg and compared its effects on CA1 hippocampal neuronal plasticity, with that of normal cage control rats. We observed that the mean area, perimeter, synaptic cleft and length of active zone of CA1 hippocampal neurons significantly decreased while dendritic arborization and number of spines significantly increased in SMg group as compared with controls. The mean thickness of the post synaptic density and total dendritic length remained unaltered. The changes may be a compensatory effect induced by exposure to microgravity; however, the effects may be transient or permanent, which need further study. These findings may be useful for designing effective prevention for those, including the astronauts, exposed to microgravity. Further, subject to confirmation we propose that SMg exposure might be useful for recovery of stroke patients.

  2. Activity-dependent Regulation of h Channel Distribution in Hippocampal CA1 Pyramidal Neurons

    National Research Council Canada - National Science Library

    Minyoung Shin; Dane M. Chetkovich

    2007-01-01

    ...) channel subunits, HCN1 and HCN2. Pyramidal neuron h channels within hippocampal area CA1 are remarkably enriched in distal apical dendrites, and this unique distribution pattern is critical for regulating dendritic excitability...

  3. Effects of retinoic acids on the dendritic morphology of cultured hippocampal neurons

    National Research Council Canada - National Science Library

    Liu, Ying; Kagechika, Hiroyuki; Ishikawa, Junko; Hirano, Hitoshi; Matsukuma, Satoshi; Tanaka, Kazuko; Nakamura, Shoji

    2008-01-01

    ...: retinoic acid receptor (RAR) and retinoid X receptor (RXR). High doses of 13‐ cis ‐RA and all‐ trans ‐RA exerted a negative effect on the cultured hippocampal neurons, while a low dose of 13...

  4. Soluble Tau has devastating effects on the structural plasticity of hippocampal granule neurons.

    Science.gov (United States)

    Bolós, M; Pallas-Bazarra, N; Terreros-Roncal, J; Perea, J R; Jurado-Arjona, J; Ávila, J; Llorens-Martín, M

    2017-12-08

    Tau is a neuronal microtubule-associated protein with countless physiological functions. Although the detrimental effects of insoluble aggregated Tau have been widely studied, recent evidence supports the notion that soluble Tau (composed mostly of monomers and dimers) is also toxic for neurons. Here we evaluated the long-term impact of a single stereotaxic injection of human soluble Tau on hippocampal granule neurons in mice. At the ultrastructural level, soluble Tau reduced the number of afferent synapses and caused a dramatic depletion of synaptic vesicles both in afferent and efferent synapses. Furthermore, the use of an RFP-expressing retrovirus revealed that soluble Tau altered the morphology of newborn granule neurons and reduced their afferent (dendritic spines) and efferent (mossy fiber terminals) connectivity. Finally, soluble Tau caused specific impairment of behavioral pattern separation capacity. Our results thus demonstrate for the first time that soluble Tau causes long-term detrimental effects on the morphology and connectivity of newborn granule neurons and that these effects correlate with impaired behavioral pattern separation skills. These data might be relevant for the field of neurodegenerative disorders, since they contribute to reinforcing the pathological roles played by distinct Tau species in vivo.

  5. Measuring Synaptic Vesicle Endocytosis in Cultured Hippocampal Neurons.

    Science.gov (United States)

    Villarreal, Seth; Lee, Sung Hoon; Wu, Ling-Gang

    2017-09-04

    During endocytosis, fused synaptic vesicles are retrieved at nerve terminals, allowing for vesicle recycling and thus the maintenance of synaptic transmission during repetitive nerve firing. Impaired endocytosis in pathological conditions leads to decreases in synaptic strength and brain functions. Here, we describe methods used to measure synaptic vesicle endocytosis at the mammalian hippocampal synapse in neuronal culture. We monitored synaptic vesicle protein endocytosis by fusing a synaptic vesicular membrane protein, including synaptophysin and VAMP2/synaptobrevin, at the vesicular lumenal side, with pHluorin, a pH-sensitive green fluorescent protein that increases its fluorescence intensity as the pH increases. During exocytosis, vesicular lumen pH increases, whereas during endocytosis vesicular lumen pH is re-acidified. Thus, an increase of pHluorin fluorescence intensity indicates fusion, whereas a decrease indicates endocytosis of the labelled synaptic vesicle protein. In addition to using the pHluorin imaging method to record endocytosis, we monitored vesicular membrane endocytosis by electron microscopy (EM) measurements of Horseradish peroxidase (HRP) uptake by vesicles. Finally, we monitored the formation of nerve terminal membrane pits at various times after high potassium-induced depolarization. The time course of HRP uptake and membrane pit formation indicates the time course of endocytosis.

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

    Directory of Open Access Journals (Sweden)

    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.

  7. Multiplex networks of cortical and hippocampal neurons revealed at different timescales.

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    Nicholas Timme

    Full Text Available Recent studies have emphasized the importance of multiplex networks--interdependent networks with shared nodes and different types of connections--in systems primarily outside of neuroscience. Though the multiplex properties of networks are frequently not considered, most networks are actually multiplex networks and the multiplex specific features of networks can greatly affect network behavior (e.g. fault tolerance. Thus, the study of networks of neurons could potentially be greatly enhanced using a multiplex perspective. Given the wide range of temporally dependent rhythms and phenomena present in neural systems, we chose to examine multiplex networks of individual neurons with time scale dependent connections. To study these networks, we used transfer entropy--an information theoretic quantity that can be used to measure linear and nonlinear interactions--to systematically measure the connectivity between individual neurons at different time scales in cortical and hippocampal slice cultures. We recorded the spiking activity of almost 12,000 neurons across 60 tissue samples using a 512-electrode array with 60 micrometer inter-electrode spacing and 50 microsecond temporal resolution. To the best of our knowledge, this preparation and recording method represents a superior combination of number of recorded neurons and temporal and spatial recording resolutions to any currently available in vivo system. We found that highly connected neurons ("hubs" were localized to certain time scales, which, we hypothesize, increases the fault tolerance of the network. Conversely, a large proportion of non-hub neurons were not localized to certain time scales. In addition, we found that long and short time scale connectivity was uncorrelated. Finally, we found that long time scale networks were significantly less modular and more disassortative than short time scale networks in both tissue types. As far as we are aware, this analysis represents the first

  8. Dietary cholesterol modulates the excitability of rabbit hippocampal CA1 pyramidal neurons.

    Science.gov (United States)

    Wang, Desheng; Schreurs, Bernard G

    2010-08-02

    Previous work has shown high dietary cholesterol can affect learning and memory including rabbit eyeblink conditioning and this effect may be due to increased membrane cholesterol and enhanced hippocampal amyloid beta production. This study investigated whether dietary cholesterol modulates rabbit hippocampal CA1 neuron membrane properties known to be involved in rabbit eyeblink conditioning. Whole-cell current clamp recordings in hippocampal neurons from rabbits fed 2 percent cholesterol or normal chow for 8 weeks revealed changes including decreased after-hyperpolarization amplitudes (AHPs) - an index of membrane excitability shown to be important for rabbit eyeblink conditioning. This index was reversed by adding copper to drinking water - a dietary manipulation that can retard rabbit eyeblink conditioning. Evidence of cholesterol effects on membrane excitability was provided by application of methyl-beta-cyclodextrin, a compound that reduces membrane cholesterol, which increased the excitability of hippocampal CA1 neurons.

  9. 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

  10. ToF-SIMS cluster ion imaging of hippocampal CA1 pyramidal rat neurons

    Science.gov (United States)

    Francis, J. T.; Nie, H.-Y.; Taylor, A. R.; Walzak, M. J.; Chang, W. H.; MacFabe, D. F.; Lau, W. M.

    2008-12-01

    Recent studies have demonstrated the power of time-of-flight secondary ion mass spectrometry (ToF-SIMS) cluster ion imaging to characterize biological structures, such as that of the rat central nervous system. A large number of the studies to date have been carried out on the "structural scale" imaging several mm 2 using mounted thin sections. In this work, we present our ToF-SIMS cluster ion imaging results on hippocampal rat brain neurons, at the cellular and sub-cellular levels. As a part of an ongoing investigation to examine gut linked metabolic factors in autism spectrum disorders using a novel rat model, we have observed a possible variation in hippocampal Cornu ammonis 1 (CA1) pyramidal neuron geometry in thin, paraformaldehyde fixed brain sections. However, the fixation process alters the tissue matrix such that much biochemical information appears to be lost. In an effort to preserve as much as possible this original information, we have established a protocol using unfixed thin brain sections, along with low dose, 500 eV Cs + pre-sputtering that allows imaging down to the sub-cellular scale with minimal sample preparation.

  11. Downregulation of CREB expression in Alzheimer's brain and in Aβ-treated rat hippocampal neurons

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    Pham Serena

    2011-08-01

    Full Text Available Abstract Background Oxidative stress plays an important role in neuronal dysfunction and neuron loss in Alzheimer's brain. Previous studies have reported downregulation of CREB-mediated transcription by oxidative stress and Aβ. The promoter for CREB itself contains cyclic AMP response elements. Therefore, we examined the expression of CREB in the hippocampal neurons of Tg2576 mice, AD post-mortem brain and in cultured rat hippocampal neurons exposed to Aβ aggregates. Results Laser Capture Microdissection of hippocampal neurons from Tg2576 mouse brain revealed decreases in the mRNA levels of CREB and its target, BDNF. Immunohistochemical analysis of Tg2576 mouse brain showed decreases in CREB levels in hippocampus and cortex. Markers of oxidative stress were detected in transgenic mouse brain and decreased CREB staining was observed in regions showing abundance of astrocytes. There was also an inverse correlation between SDS-extracted Aβ and CREB protein levels in Alzheimer's post-mortem hippocampal samples. The levels of CREB-regulated BDNF and BIRC3, a caspase inhibitor, decreased and the active cleaved form of caspase-9, a marker for the intrinsic pathway of apoptosis, was elevated in these samples. Exposure of rat primary hippocampal neurons to Aβ fibrils decreased CREB promoter activity. Decrease in CREB mRNA levels in Aβ-treated neurons was reversed by the antioxidant, N-acetyl cysteine. Overexpression of CREB by adenoviral transduction led to significant protection against Aβ-induced neuronal apoptosis. Conclusions Our findings suggest that chronic downregulation of CREB-mediated transcription results in decrease of CREB content in the hippocampal neurons of AD brain which may contribute to exacerbation of disease progression.

  12. Effects of GSM 1800 MHz on dendritic development of cultured hippocampal neurons.

    Science.gov (United States)

    Ning, Wei; Xu, Shu-jun; Chiang, Huai; Xu, Zheng-ping; Zhou, Su-ya; Yang, Wei; Luo, Jian-hong

    2007-12-01

    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. 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. 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 exposed to the GSM 1800 MHz microwaves with 0.8 W/kg. These data indicate that the chronic exposure to 2.4 W/kg GSM 1800 MHz microwaves during the early developmental stage may affect dendritic development and the formation of excitatory synapses of hippocampal neurons in culture.

  13. Neuroprotective effects of lotus seedpod procyanidins on extremely low frequency electromagnetic field-induced neurotoxicity in primary cultured hippocampal neurons.

    Science.gov (United States)

    Yin, Chunchun; Luo, Xiaoping; Duan, Yuqing; Duan, Wenyi; Zhang, Haihui; He, Yuanqing; Sun, Guibo; Sun, Xiaobo

    2016-08-01

    The present study investigated the protective effects of lotus seedpod procyanidins (LSPCs) on extremely low frequency electromagnetic field (ELF-EMF)-induced neurotoxicity in primary cultured rat hippocampal neurons and the underlying molecular mechanism. The results of MTT, morphological observation, superoxide dismutase (SOD) and malondialdehyde (MDA) assays showed that compared with control, incubating neurons under ELF-EMF exposure significantly decreased cell viability and increased the number of apoptotic cells, whereas LSPCs evidently protected the hippocampal neurons against ELF-EMF-induced cell damage. Moreover, a certain concentration of LSPCs inhibited the elevation of intracellular reactive oxygen species (ROS) and Ca(2+) level, as well as prevented the disruption of mitochondrial membrane potential induced by ELF-EMF exposure. In addition, supplementation with LSPCs could alleviate DNA damage, block cell cycle arrest at S phase, and inhibit apoptosis and necrosis of hippocampal neurons under ELF-EMF exposure. Further study demonstrated that LSPCs up-regulated the activations of Bcl-2, Bcl-xl proteins and suppressed the expressions of Bad, Bax proteins caused by ELF-EMF exposure. In conclusion, these findings revealed that LSPCs protected against ELF-EMF-induced neurotoxicity through inhibiting oxidative stress and mitochondrial apoptotic pathway. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  14. Diabetes impairs learning performance and affects the mitochondrial function of hippocampal pyramidal neurons.

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    Ye, Lin; Wang, Feng; Yang, Rui-Hua

    2011-09-09

    Previous research has demonstrated that diabetes induces learning and memory deficits. However, the mechanism of memory impairment induced by diabetes is poorly understood. The present study investigated the effect of streptozotocin (STZ)-induced diabetes on spatial learning and memory using the Morris Water Maze. The effects of diabetes on CA1 pyramidal neurons in hippocampus were also examined. Diabetes impaired spatial learning and memory of rats. Diabetes induced the apoptosis of neurons and translocation of Bax from cytoplasm to mitochondria. On the contrary, diabetes induced cytochrome c release into the cytoplasm from mitochondria. Release of Cyt-c from mitochondria into cytoplasm may play a role in apoptosis of the CA1 pyramidal neurons, which resulted in a decrease of the number of neurons in hippocampus and impaired the performance function. These results partially explain the mechanism of the effect of diabetes on learning and memory. To protect mitochondrial function is possible candidate for preventing the impairments of diabetes on hippocampal function. Copyright © 2011 Elsevier B.V. All rights reserved.

  15. Eltrombopag, a thrombopoietin mimetic, crosses the blood-brain barrier and impairs iron-dependent hippocampal neuron dendrite development.

    Science.gov (United States)

    Bastian, T W; Duck, K A; Michalopoulos, G C; Chen, M J; Liu, Z-J; Connor, J R; Lanier, L M; Sola-Visner, M C; Georgieff, M K

    2017-03-01

    Essentials Potential neurodevelopmental side effects of thrombopoietin mimetics need to be considered. The effects of eltrombopag (ELT) on neuronal iron status and dendrite development were assessed. ELT crosses the blood-brain barrier and causes iron deficiency in developing neurons. ELT blunts dendrite maturation, indicating a need for more safety studies before neonatal use. Background Thrombocytopenia is common in sick neonates. Thrombopoietin mimetics (e.g. eltrombopag [ELT]) might provide an alternative therapy for selected neonates with severe and prolonged thrombocytopenia, and for infants and young children with different varieties of thrombocytopenia. However, ELT chelates intracellular iron, which may adversely affect developing organs with high metabolic requirements. Iron deficiency (ID) is particularly deleterious during brain development, impairing neuronal myelination, dopamine signaling and dendritic maturation and ultimately impairing long-term neurological function (e.g. hippocampal-dependent learning and memory). Objective To determine whether ELT crosses the blood-brain barrier (BBB), causes neuronal ID and impairs hippocampal neuron dendrite maturation. Methods ELT transport across the BBB was assessed using primary bovine brain microvascular endothelial cells. Embryonic mouse primary hippocampal neuron cultures were treated with ELT or deferoxamine (DFO, an iron chelator) from 7 days in vitro (DIV) through 14 DIV and assessed for gene expression and neuronal dendrite complexity. Results ELT crossed the BBB in a time-dependent manner. 2 and 6 μm ELT increased Tfr1 and Slc11a2 (iron-responsive genes involved in neuronal iron uptake) mRNA levels, indicating neuronal ID. 6 μm ELT, but not 2 μm ELT, decreased BdnfVI, Camk2a and Vamp1 mRNA levels, suggesting impaired neuronal development and synaptic function. Dendrite branch number and length were reduced in 6 μm ELT-treated neurons, resulting in blunted dendritic arbor complexity that

  16. Hippocampal adaptive response following extensive neuronal loss in an inducible transgenic mouse model.

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    Kristoffer Myczek

    Full Text Available Neuronal loss is a common component of a variety of neurodegenerative disorders (including Alzheimer's, Parkinson's, and Huntington's disease and brain traumas (stroke, epilepsy, and traumatic brain injury. One brain region that commonly exhibits neuronal loss in several neurodegenerative disorders is the hippocampus, an area of the brain critical for the formation and retrieval of memories. Long-lasting and sometimes unrecoverable deficits caused by neuronal loss present a unique challenge for clinicians and for researchers who attempt to model these traumas in animals. Can these deficits be recovered, and if so, is the brain capable of regeneration following neuronal loss? To address this significant question, we utilized the innovative CaM/Tet-DT(A mouse model that selectively induces neuronal ablation. We found that we are able to inflict a consistent and significant lesion to the hippocampus, resulting in hippocampally-dependent behavioral deficits and a long-lasting upregulation in neurogenesis, suggesting that this process might be a critical part of hippocampal recovery. In addition, we provide novel evidence of angiogenic and vasculature changes following hippocampal neuronal loss in CaM/Tet-DTA mice. We posit that angiogenesis may be an important factor that promotes neurogenic upregulation following hippocampal neuronal loss, and both factors, angiogenesis and neurogenesis, can contribute to the adaptive response of the brain for behavioral recovery.

  17. Turmeric extract inhibits apoptosis of hippocampal neurons of trimethyltin-exposed rats.

    Science.gov (United States)

    Yuliani, S; Widyarini, S; Mustofa; Partadiredja, G

    2017-01-01

    The aim of the present study was to reveal the possible antiapoptotic effect of turmeric (Curcuma longa Linn.) on the hippocampal neurons of rats exposed to trimethyltin (TMT). Oxidative damage in the hippocampus can induce the apoptosis of neurons associated with the pathogenesis of dementiaMETHODS. The ethanolic turmeric extract and a citicoline (as positive control) solution were administered to the TMT-exposed rats for 28 days. The body weights of rats were recorded once a week. The hippocampal weights and imumunohistochemical expression of caspase 3 proteins in the CA1 and CA2-CA3 regions of the hippocampi were examined at the end of the experiment. Immunohistochemical analysis showed that the injection of TMT increased the expression of caspase 3 in the CA1 and CA2-CA3 regions of hippocampus. TMT also decreased the body and hippocampal weights. Furthermore, the administration of 200 mg/kg bw dose of turmeric extract decreased the caspase 3 expression in the CA2-CA3 pyramidal neurons but not in the CA1 neurons. It also prevented the decrease of the body and hippocampal weights. We suggest that the 200 mg/kg bw dose of turmeric extract may exert antiapoptotic effect on the hippocampal neurons of the TMT-exposed rats (Tab. 1, Fig. 3, Ref. 49).

  18. Altered intrinsic excitability of hippocampal CA1 pyramidal neurons in aged PDAPP mice

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    Francesco eTamagnini

    2015-10-01

    Full Text Available Amyloidopathy involves the accumulation of insoluble amyloid β (Aβ species in the brain’s parenchyma and is a key histopathological hallmark of Alzheimer’s disease (AD. Work on transgenic mice that overexpress A suggests that elevated A levels in the brain are associated with aberrant epileptiform activity and increased intrinsic excitability of CA1 hippocampal neurons. In this study we examined if similar changes could be observed in hippocampal CA1 pyramidal neurons from aged PDAPP mice (20-23 month old, Indiana mutation: V717F on APP gene compared to their age-matched WT littermate controls. Whole-cell current clamp recordings revealed that sub-threshold intrinsic properties, such as input resistance, resting membrane potential and hyperpolarization activated sag were unaffected, but capacitance was significantly decreased in the transgenic animals. No differences between genotypes were observed in the overall number of action potentials (AP elicited by 500 ms supra-threshold current stimuli. PDAPP neurons, however, exhibited higher instantaneous firing frequencies after accommodation in response to high intensity current injections. The AP waveform was narrower and shorter in amplitude in PDAPP mice: these changes, according to our in silico model of a CA1/3 pyramidal neuron, depended on the respective reduction and increase of Na+ and K+ voltage-gated channels maximal conductances. Finally, the after-hyperpolarization (AHP, seen after the first AP evoked by a +300 pA current injection and after 50 Hz AP bursts, was more pronounced in PDAPP mice.These data show that Aβ-overexpression in aged mice altered the capacitance, the neuronal firing and the AP waveform of CA1 pyramidal neurons. Some of these findings are consistent with previous work on younger PDAPP, they also show important differences that can be potentially ascribed to the interaction between amyloidopathy and ageing. Such a change of IE properties over time

  19. Short communication: hippocampal neuronal activity and imprinting in the behaving domestic chick.

    Science.gov (United States)

    Nicol, A U; Brown, M W; Horn, G

    1998-08-01

    The hippocampus of the chick projects to the intermediate and medial part of the hyperstriatum ventrale (IMHV) which stores information acquired through the learning process of imprinting. We have investigated whether the response properties of hippocampal neurons are similar to those of IMHV neurons. Chicks were imprinted by exposure, one group (n = 7) to a rotating red box (RB), the other (n = 5) to a rotating blue cylinder (BC). Four chicks were untrained. The following day, when the chicks were approximately 48 h old, neuronal activity was recorded in the left hippocampus. The proportion of neurons responding to the RB and that to the BC in untrained chicks were compared with the proportions in trained birds. (i) In RB-trained chicks both the proportion responding to the RB and that to the BC were significantly increased. (ii) In BC-trained chicks no significant effect on these proportions was found. Of the responsive neurons some were colour (red or blue) sensitive and others were shape (box or cylinder) sensitive; the proportions so responsive were not influenced by training condition. Certain neurons responded significantly differently when a stimulus was 0.5 m or 2 m from the chick (35%; d-sensitive); very few neurons were equivalently responsive to a stimulus at both distances (3%; d-invariant). These proportions were not significantly affected by training condition. Hippocampal responses are compared with those in the left IMHV. It is concluded that IMHV responses do not passively reflect those of hippocampal neurons.

  20. Task-dependent and independent synchronous activity of monkey hippocampal neurons in real and virtual translocation.

    Science.gov (United States)

    Hori, Etsuro; Tabuchi, Eiichi; Matsumura, Nobuhisa; Ono, Taketoshi; Nishijo, Hisao

    2011-01-01

    Previous neurophysiological and behavioral studies relate hippocampal functions to place learning and memory, and encoding of task (or context)-specific information. Encoding of both task-specific information and own location is essential for episodic memory and for animals to navigate to reward-related places. It is suggested that different neural circuits with different assemblies of different hippocampal neurons are created in different environments or behavioral contexts for the hippocampal formation (HF) to encode and retrieve episodic memory. To investigate whether synchronous activity of hippocampal neurons, suggesting functional connectivity between those neurons, is task and position dependent, multiple single unit activities were recorded during performance of real and virtual translocation (VT) tasks. The monkey moved to one of four reward areas by driving a cab (real translocation) or by moving a pointer on a monitor. Of 163 neuron pairs, significant peaks in cross-correlograms (CCGs) were observed in 98 pairs. Most CCGs had positive peaks within 50 ms. Task-dependent cross-correlations (CCRs) were observed in 44% of the neuron pairs, and similarly observed in both the real and VT tasks. These CCRs were frequently observed in pyramidal vs. pyramidal neuron pairs with positive peak and peak shift. However, no consistent patterns of peak polarity, peak shift, and neuronal types were seen in task-independent CCRs. There was no significant difference in frequency of CCG peaks between real and VT tasks. These results suggest that the task-dependent information may be encoded by interaction among pyramidal neurons, and the common information across tasks may be encoded by interaction among pyramidal neurons and interneurons in the HF. These neuronal populations could provide a neural basis for episodic memory to disambiguously guide animals to places associated with reward in different situations.

  1. Task-Dependent and Independent Synchronous Activity of Monkey Hippocampal Neurons in Real and Virtual Translocation

    Science.gov (United States)

    Hori, Etsuro; Tabuchi, Eiichi; Matsumura, Nobuhisa; Ono, Taketoshi; Nishijo, Hisao

    2011-01-01

    Previous neurophysiological and behavioral studies relate hippocampal functions to place learning and memory, and encoding of task (or context)-specific information. Encoding of both task-specific information and own location is essential for episodic memory and for animals to navigate to reward-related places. It is suggested that different neural circuits with different assemblies of different hippocampal neurons are created in different environments or behavioral contexts for the hippocampal formation (HF) to encode and retrieve episodic memory. To investigate whether synchronous activity of hippocampal neurons, suggesting functional connectivity between those neurons, is task and position dependent, multiple single unit activities were recorded during performance of real and virtual translocation (VT) tasks. The monkey moved to one of four reward areas by driving a cab (real translocation) or by moving a pointer on a monitor. Of 163 neuron pairs, significant peaks in cross-correlograms (CCGs) were observed in 98 pairs. Most CCGs had positive peaks within 50 ms. Task-dependent cross-correlations (CCRs) were observed in 44% of the neuron pairs, and similarly observed in both the real and VT tasks. These CCRs were frequently observed in pyramidal vs. pyramidal neuron pairs with positive peak and peak shift. However, no consistent patterns of peak polarity, peak shift, and neuronal types were seen in task-independent CCRs. There was no significant difference in frequency of CCG peaks between real and VT tasks. These results suggest that the task-dependent information may be encoded by interaction among pyramidal neurons, and the common information across tasks may be encoded by interaction among pyramidal neurons and interneurons in the HF. These neuronal populations could provide a neural basis for episodic memory to disambiguously guide animals to places associated with reward in different situations. PMID:21808612

  2. Altered adult hippocampal neuronal maturation in a rat model of fetal alcohol syndrome.

    Science.gov (United States)

    Gil-Mohapel, Joana; Boehme, Fanny; Patten, Anna; Cox, Adrian; Kainer, Leah; Giles, Erica; Brocardo, Patricia S; Christie, Brian R

    2011-04-12

    Exposure to ethanol during pregnancy can be devastating to the developing nervous system, leading to significant central nervous system dysfunction. The hippocampus, one of the two brain regions where neurogenesis persists into adulthood, is particularly sensitive to the teratogenic effects of ethanol. In the present study, we tested a rat model of fetal alcohol syndrome (FAS) with ethanol administered via gavage throughout all three trimester equivalents. Subsequently, we assessed cell proliferation, as well as neuronal survival, and differentiation in the dentate gyrus of the hippocampus of adolescent (35 days old), young adult (60 days old) and adult (90 days old) Sprague-Dawley rats. Using both extrinsic (bromodeoxyuridine) and intrinsic (Ki-67) markers, we observed no significant alterations in cell proliferation and survival in ethanol-exposed animals when compared with their pair-fed and ad libitum controls. However, we detected a significant increase in the number of new immature neurons in animals that were exposed to ethanol throughout all three trimester equivalents. This result might reflect a compensatory mechanism to counteract the deleterious effects of prenatal ethanol exposure or an ethanol-induced arrest of the neurogenic process at the early neuronal maturation stages. Taken together these results indicate that exposure to ethanol during the period of brain development causes a long-lasting dysregulation of the neurogenic process, a mechanism that might contribute, at least in part, to the hippocampal deficits that have been reported in rodent models of FAS. Copyright © 2011 Elsevier B.V. All rights reserved.

  3. Development of multiple calcium channel types in cultured mouse hippocampal neurons.

    Science.gov (United States)

    Chameau, P; Lucas, P; Melliti, K; Bournaud, R; Shimahara, T

    1999-05-01

    The development of multiple calcium channel activities was studied in mouse hippocampal neurons in culture, using the patch-clamp technique. A depolarizing pulse (40-50 ms duration) from the holding potential of -80 mV to levels more depolarized than -40 mV produced a low threshold T-type current. The T-type current was observed in 52% of four days in vitro neurons. The number of neurons which expressed T-type current decreased with age of culture, so that the current was detected in only 18% of neurons after 16 days in vitro. The T-type current densities varied between 1.9 pA/pF and 3.29 pA/pF in the mean values during the period studied (4-16 days in vitro). A depolarizing pulse from -80 mV to levels more depolarized than -35 mV evoked a high threshold calcium channel current. The high threshold current density increased in the mean values from 3.9 pA/pF in four days in vitro neurons to 28 pA/pF in 16 days in vitro neurons. We have then examined the effect of nifedipine, omega-Agatoxin IVA and omega-conotoxin GVIA on the high threshold current. Nifedipine (1-5 microM) sensitive current density stayed in the range of 1.9-2.1 pA/pF during 4-16 days in vitro, while omega-Agatoxin IVA (200 nM) sensitive current density increased in the mean values from 1.54 pA/pF in four days in vitro neurons to 21.5 pA/pF in 16 days in vitro neurons. The omega-conotoxin GVIA sensitive N-type channel current was maximum at eight days in vitro (5.44 pA/pF) and it reduced progressively to reach almost half (2.46 pA/pF) in 16 days in vitro neurons. These results showed that diverse subtypes of calcium channels change in density during the early period of culture. We suggest that the temporal expression of each type of channel may be linked to the development of neural activities.

  4. Dopamine receptor activation reorganizes neuronal ensembles during hippocampal sharp waves in vitro.

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    Takeyuki Miyawaki

    Full Text Available Hippocampal sharp wave (SW/ripple complexes are thought to contribute to memory consolidation. Previous studies suggest that behavioral rewards facilitate SW occurrence in vivo. However, little is known about the precise mechanism underlying this enhancement. Here, we examined the effect of dopaminergic neuromodulation on spontaneously occurring SWs in acute hippocampal slices. Local field potentials were recorded from the CA1 region. A brief (1 min treatment with dopamine led to a persistent increase in the event frequency and the magnitude of SWs. This effect lasted at least for our recording period of 45 min and did not occur in the presence of a dopamine D1/D5 receptor antagonist. Functional multineuron calcium imaging revealed that dopamine-induced SW augmentation was associated with an enriched repertoire of the firing patterns in SW events, whereas the overall tendency of individual neurons to participate in SWs and the mean number of cells participating in a single SW were maintained. Therefore, dopaminergic activation is likely to reorganize cell assemblies during SWs.

  5. Calcium regulation in long-term changes of neuronal excitability in the hippocampal formation

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    Mody, I.

    1985-01-01

    The regulation of calcium (Ca/sup 2 +/) was examined during long-term changes of neuronal excitability in the mammalian CNS. The preparations under investigation included the kindling model of epilepsy, a genetic form of epilepsy and long-term potentiation (LTP) of neuronal activity. The study also includes a discussion of the possible roles of a neuron-specific calcium-binding protein (CaBP). The findings are summarized as follows: (1) CaBP was found to have an unequal distribution in various cortical areas of the rat with higher levels in ventral structures. (2) The decline in CaBP was correlated to the number of evoked afterdischarges (AD's) during kindling-induced epilepsy. (3) Marked changes in CaBP levels were also found in the brains of the epileptic strain of mice (El). The induction of seizures further decreased the levels of CaBP in the El mice, indicating a possible genetic impairment of neuronal Ca/sup 2 +/ homeostasis in the El strain. (4) The levels of total hippocampal Ca/sup 2 +/ and Zn/sup 2 +/ were measured by atomic absorption spectrophotometry in control and commissural-kindled animals. (5) To measure Ca/sup 2 +/-homeostasis, the kinetic analysis of /sup 45/Ca uptake curves was undertaken in the in vitro hippocampus. (6) The kinetic analysis of /sup 45/Ca uptake curves revealed that Ca/sup 2 +/-regulation of the hippocampus is impaired following amygdala- and commissural kindling. (7). A novel form of long-term potentiation (LTP) of neuronal activity in the CA1 region of the hippocampus is described. The findings raise the possibility that the Ca/sup 2 +/ necessary for induction of LTP may be derived from an intraneuronal storage site.

  6. Study on dynamic characteristics' change of hippocampal neuron reduced models caused by the Alzheimer's disease.

    Science.gov (United States)

    Peng, Yueping; Wang, Jue; Zheng, Chongxun

    2016-01-01

    In the paper, based on the electrophysiological experimental data, the Hippocampal neuron reduced model under the pathology condition of Alzheimer's disease (AD) has been built by modifying parameters' values. The reduced neuron model's dynamic characteristics under effect of AD are comparatively studied. Under direct current stimulation, compared with the normal neuron model, the AD neuron model's dynamic characteristics have obviously been changed. The neuron model under the AD condition undergoes supercritical Andronov-Hopf bifurcation from the rest state to the continuous discharge state. It is different from the neuron model under the normal condition, which undergoes saddle-node bifurcation. So, the neuron model changes into a resonator with monostable state from an integrator with bistable state under AD's action. The research reveals the neuron model's dynamic characteristics' changing under effect of AD, and provides some theoretic basis for AD research by neurodynamics theory.

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

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    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.

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

    NARCIS (Netherlands)

    Kole, Maarten H. P.; Czéh, Boldizsár; Fuchs, Eberhard

    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

  9. Computational Model of a Positive BDNF Feedback Loop in Hippocampal Neurons Following Inhibitory Avoidance Training

    Science.gov (United States)

    Zhang, Yili; Smolen, Paul; Alberini, Cristina M.; Baxter, Douglas A.; Byrne, John H.

    2016-01-01

    Inhibitory avoidance (IA) training in rodents initiates a molecular cascade within hippocampal neurons. This cascade contributes to the transition of short- to long-term memory (i.e., consolidation). Here, a differential equation-based model was developed to describe a positive feedback loop within this molecular cascade. The feedback loop begins…

  10. VPS35 regulates developing mouse hippocampal neuronal morphogenesis by promoting retrograde trafficking of BACE1

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    Chun-Lei Wang

    2012-10-01

    VPS35, a major component of the retromer, plays an important role in the selective endosome-to-Golgi retrieval of membrane proteins. Dysfunction of retromer is a risk factor for neurodegenerative disorders, but its function in developing mouse brain remains poorly understood. Here we provide evidence for VPS35 promoting dendritic growth and maturation, and axonal protein transport in developing mouse hippocampal neurons. Embryonic hippocampal CA1 neurons suppressing Vps35 expression by in utero electroporation of its micro RNAs displayed shortened apical dendrites, reduced dendritic spines, and swollen commissural axons in the neonatal stage, those deficits reflecting a defective protein transport/trafficking in developing mouse neurons. Further mechanistic studies showed that Vps35 depletion in neurons resulted in an impaired retrograde trafficking of BACE1 (β1-secretase and altered BACE1 distribution. Suppression of BACE1 expression in CA1 neurons partially rescued both dendritic and axonal deficits induced by Vps35-deficiency. These results thus demonstrate that BACE1 acts as a critical cargo of retromer in vitro and in vivo, and suggest that VPS35 plays an essential role in regulating apical dendritic maturation and in preventing axonal spheroid formation in developing hippocampal neurons.

  11. The Effect of Vitamin D Treatment On Nerve Growth Factor (NGF) Release From Hippocampal Neurons.

    Science.gov (United States)

    Gezen-Ak, Duygu; Dursun, Erdinç; Yilmazer, Selma

    2014-06-01

    Vitamin D, the main function of which is thought to be the maintenance of calcium and phosphate homeostasis and bone structure, has been shown in recent studies to have important roles in brain development as well. A certain vitamin D receptor (VDR) gene haplotype was reported, for the first time by our group, to increase the risk of developing Alzheimer's disease. Our studies also showed that vitamin D prevents beta amyloid-induced calcium elevation and toxicity that target nerve growth factor (NGF) release in cortical neurons; beta amyloid suppresses VDR expression and the disruption of vitamin D-VDR pathway mimics beta amyloid-induced neurodegeneration. In this study, our aim was to investigate the effects of vitamin D on the NGF release from hippocampal neurons. Primary hippocampal neuron cultures that were prepared from 18-day-old Sprague-Dawley rat embryos were treated with vitamin D for 48 hours. The alteration in the NGF release was determined with ELISA. Cytotoxicity tests were also performed for all groups. The NGF release in vitamin D-treated group was significantly higher than in untreated control group. The protective effect of vitamin D against cytotoxicity was also observed. Our results indicated that vitamin D regulates the release of NGF, a very important molecule for neuronal survival of hippocampal neurons as well as cortical neurons.

  12. Novelty-induced correlation between visual neurons and the hippocampal theta rhythm in sleep and wakefulness.

    Science.gov (United States)

    Pedemonte, Marisa; Gambini, Juan P; Velluti, Ricardo A

    2005-11-16

    Various rhythms have been shown to affect sensory processing such as the waking-sleep cycle and the hippocampal theta waves. Changes in the firing of visual lateral geniculate nucleus neurons have been reported to be dependent on the animal's behavioral state. The lateral geniculate extracellular neuronal firing and hippocampal field activity were recorded in chronically implanted animals to analyze the relationship during quiet wakefulness and sleep associated with stimulation shifts that may introduce novelty. During wakefulness, a change in light flash stimulation pattern (stimuli frequency shift, stimuli on and off) caused an increment in the theta band power in 100% of the cases and a phase-locking of the spikes in 53% of the recorded neurons. During slow wave sleep, there were no consistent changes in the theta power notwithstanding 13% of the neurons exhibited phase-locking, i.e., novelty may induce changes in the temporal correlation of visual neuronal activity with the hippocampal theta rhythm in sleep. The present results suggest that visual processing in slow wave sleep exists, while auditory information and learning were reported during slow wave sleep in animals and newborn humans. The changes in the theta power as well as in the neuronal phase-locking amount indicate that in slow wave sleep, the ability of the hippocampus to detect/process novelty, although present, may be decreased. This is consistent with the noticeable decrease in awareness of the environment during sleep.

  13. Adult-generated hippocampal neurons allow the flexible use of spatially precise learning strategies.

    Science.gov (United States)

    Garthe, Alexander; Behr, Joachim; Kempermann, Gerd

    2009-01-01

    Despite enormous progress in the past few years the specific contribution of newly born granule cells to the function of the adult hippocampus is still not clear. We hypothesized that in order to solve this question particular attention has to be paid to the specific design, the analysis, and the interpretation of the learning test to be used. We thus designed a behavioral experiment along hypotheses derived from a computational model predicting that new neurons might be particularly relevant for learning conditions, in which novel aspects arise in familiar situations, thus putting high demands on the qualitative aspects of (re-)learning.In the reference memory version of the water maze task suppression of adult neurogenesis with temozolomide (TMZ) caused a highly specific learning deficit. Mice were tested in the hidden platform version of the Morris water maze (6 trials per day for 5 days with a reversal of the platform location on day 4). Testing was done at 4 weeks after the end of four cycles of treatment to minimize the number of potentially recruitable new neurons at the time of testing. The reduction of neurogenesis did not alter longterm potentiation in CA3 and the dentate gyrus but abolished the part of dentate gyrus LTP that is attributed to the new neurons. TMZ did not have any overt side effects at the time of testing, and both treated mice and controls learned to find the hidden platform. Qualitative analysis of search strategies, however, revealed that treated mice did not advance to spatially precise search strategies, in particular when learning a changed goal position (reversal). New neurons in the dentate gyrus thus seem to be necessary for adding flexibility to some hippocampus-dependent qualitative parameters of learning.Our finding that a lack of adult-generated granule cells specifically results in the animal's inability to precisely locate a hidden goal is also in accordance with a specialized role of the dentate gyrus in generating a metric

  14. In Vivo AAV1 Transduction With hRheb(S16H) Protects Hippocampal Neurons by BDNF Production

    OpenAIRE

    Jeon, Min-Tae; Nam, Jin Han; Shin, Won-Ho; Leem, Eunju; Jeong, Kyoung Hoon; Jung, Un Ju; Bae, Young-Seuk; Jin, Young-Ho; Kholodilov, Nikolai; Burke, Robert E.; Lee, Seok-Geun; Jin, Byung Kwan; Kim, Sang Ryong

    2015-01-01

    Recent evidence has shown that Ras homolog enriched in brain (Rheb) is dysregulated in Alzheimer's disease (AD) brains. However, it is still unclear whether Rheb activation contributes to the survival and protection of hippocampal neurons in the adult brain. To assess the effects of active Rheb in hippocampal neurons in vivo, we transfected neurons in the cornu ammonis 1 (CA1) region in normal adult rats with an adeno-associated virus containing the constitutively active human Rheb (hRheb(S16...

  15. Accumulating microglia phagocytose injured neurons in hippocampal slice cultures: involvement of p38 MAP kinase.

    Directory of Open Access Journals (Sweden)

    Takahiro Katayama

    Full Text Available In this study, microglial migration and phagocytosis were examined in mouse organotypic hippocampal slice cultures, which were treated with N-methyl-D-aspartate (NMDA to selectively injure neuronal cells. Microglial cells were visualized by the expression of enhanced green fluorescent protein. Daily observation revealed microglial accumulation in the pyramidal cell layer, which peaked 5 to 6 days after NMDA treatment. Time-lapse imaging showed that microglia migrated to the pyramidal cell layer from adjacent and/or remote areas. There was no difference in the number of proliferating microglia between control and NMDA-treated slices in both the pyramidal cell layer and stratum radiatum, suggesting that microglial accumulation in the injured areas is mainly due to microglial migration, not to proliferation. Time-lapse imaging also showed that the injured neurons, which were visualized by propidium iodide (PI, disappeared just after being surrounded by microglia. Daily observation revealed that the intensity of PI fluorescence gradually attenuated, and this attenuation was suppressed by pretreatment with clodronate, a microglia toxin. These findings suggest that accumulating microglia phagocytosed injured neurons, and that PI fluorescence could be a useful indicator for microglial phagocytosis. Using this advantage to examine microglial phagocytosis in living slice cultures, we investigated the involvements of mitogen-activated protein (MAP kinases in microglial accumulation and phagocytosis. p38 MAP kinase inhibitor SB203580, but not MAP kinase/extracellular signal-regulated kinase inhibitor PD98059 or c-Jun N-terminal kinase inhibitor SP600125, suppressed the attenuation of PI fluorescence. On the other hand, microglial accumulation in the injured areas was not inhibited by any of these inhibitors. These data suggest that p38 MAP kinase plays an important role in microglial phagocytosis of injured neurons.

  16. Low Dose Radiation Overcomes Diabetes-induced Suppression of Hippocampal Neuronal Cell Proliferation in Rats

    Science.gov (United States)

    Kim, Sang-Ki; Hong, Seong-Eon; Lee, Taeck-Hyun; Kim, Chang-Ju

    2006-01-01

    We investigated the effect of low dose radiation on diabetes induced suppression of neurogenesis in the hippocampal dentate gyrus of rat. After 0.01 Gy, 0.1 Gy, 1 Gy and 10 Gy radiation was delivered, the dentate gyrus of hippocampus of streptozotocin (STZ)-induced diabetic rats were evaluated using immunohistochemistry for 5-bromo-2-deoxyuridine (BrdU), caspase-3, and terminal deoxynucleotidyl transferase-mediated nick end-labeling (TUNEL) staining. The number of BrdU positive cells in the non-diabetic rats, diabetic rats without radiation, diabetic rats with 0.01 Gy radiation, diabetic rats with 0.1 Gy radiation, diabetic rats with 1 Gy radiation and diabetic rats with 10 Gy radiation were 55.4±8.5/mm2, 33.3±6.4/mm2, 67.7±10.5/mm2, 66.6±10.0/mm2, 23.5±6.3/mm2and 14.3±7.2/mm2, respectively. The number of caspase-3 positive cells was 132.6±37.4/mm2, 378.6±99.1/mm2, 15.0±2.8/mm2, 57.1±16.9/mm2, 191.8±44.8/mm2and 450.4±58.3/mm2, respectively. The number of TUNEL-positive cells was 24.5±2.0/mm2, 21.7±4.0/mm2, 20.4±2.0/mm2, 18.96±2.1/mm2, 58.3±7.9/mm2, and 106.0±9.8/mm2, respectively. These results suggest low doses of radiation paradoxically improved diabetes induced neuronal cell suppression in the hippocampal dentate gyrus of rat. PMID:16778397

  17. An old test for new neurons: refining the Morris water maze to study the functional relevance of adult hippocampal neurogenesis

    Directory of Open Access Journals (Sweden)

    Alexander eGarthe

    2013-05-01

    Full Text Available The Morris water maze represents the de-facto standard for testing hippocampal function in laboratory rodents. In the field of adult hippocampal neurogenesis, however, using this paradigm to assess the functional relevance of the new neurons yielded surprisingly inconsistent results. While some authors found aspects of water maze performance to be linked to adult neurogenesis, others obtained different results or could not demonstrate any effect of manipulating adult neurogenesis.In this review we discuss evidence that the large diversity of protocols and setups used is an important aspect in interpreting the differences in the results that have been obtained. Even simple parameters such as pool size, number and configuration of visual landmarks, or number of trials can become highly relevant for getting the new neurons involved at all. Sets of parameters are often chosen with implicit or explicit concepts in mind and these might lead to different views on the function of adult-generated neurons.We propose that the classical parameters usually used to measure spatial learning performance in the water maze might not be particularly well suited to sensitively and specifically detect the supposedly highly specific functional changes elicited by the experimental modulation of adult hippocampal neurogenesis. As adult neurogenesis is supposed to affect specific aspects of information processing only in the hippocampus, any claim for a functional relevance of the new neurons has to be based on hippocampus-specific parameters. We also placed a special emphasis on the fact that the DG facilitates the differentiation between contexts as opposed to just differentiating places.In conclusion, while the Morris water maze has proven to be one of the most effective testing paradigms to assess hippocampus-dependent spatial learning, new and more specific questions ask for new parameters. Therefore, the full potential of the water maze task remains to be tapped.

  18. Regulation of dopamine quantal size in midbrain and hippocampal neurons.

    Science.gov (United States)

    Pothos, Emmanuel N

    2002-03-10

    Since the pioneering work of Bernard Katz and his colleagues decades ago, neurotransmitter quantal size (defined as the number of neurotransmitter molecules released by a single synaptic vesicle during exocytosis) is often modeled as invariant. This assumption had tremendous implications for basic research on synaptic plasticity. For instance, it focused attention on the postsynaptic rather than the presynaptic component in studies of learning and memory (the field of long-term potentiation comes to mind as the best example). Furthermore, this assumption somehow 'spilled over' onto studies of monoamine neurotransmitters, which apparently use diffusion and slow action to exert their modulatory effects, in contrast to the fast acting neurotransmitters studied by Katz. Consequently, research on dopamine-related diseases (e.g. psychotic and movement disorders) did not pay as much attention to presynaptic mechanisms that regulate dopamine release, as to postsynaptic receptor action. Part of the problem, of course, has been the lack of technology to directly measure quanta from presynaptic sites and the obligatory reliance on measurements of miniature postsynaptic potentials (minis) for reaching conclusions about presynaptic quantal events. Due to the introduction of the carbon fiber amperometric microelectrode in tissue electrophysiology, initially by Francois Gonon (University of Bordeaux) and then by Mark Wightman (University of North Carolina), we were able to directly measure dopamine quanta from neurites of cultured midbrain dopamine neurons by amperometry. This was the first approach to provide direct measurement of the number of molecules and kinetics of presynaptic quantal release from CNS neuronal terminals. The interventions altering dopamine quantal size are so far the following. (1) Alteration of neurotransmitter synthesis--an increase of cytosolic dopamine availability (e.g. by exposure to L-DOPA) increases quantal size and a decrease of cytosolic dopamine

  19. 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...... reveal a novel regulatory mechanism by which Zbtb20 suppresses the acquisition of an isocortical fate during archicortical neurogenesis to ensure commitment to a CA1 pyramidal neuron fate. We further show that the expression pattern of Zbtb20 is evolutionary conserved in the fetal human hippocampus...

  20. Characterization of formation and trace rhythm reproduction by rabbit hippocampal neurons during early and late ontogeny.

    Science.gov (United States)

    Kopytova, F V; Mednikova, Yu S

    2007-03-01

    The formation and reproduction of memory traces by hippocampal neurons were studied and a relationship between the number of presented series of periodical electrocutaneous stimulation and degree of trace acquisition of the rhythm, on the one hand, and rabbit age (6-30 days, 1, 4-5, and 7 years), on the other, was detected. The hippocampus of 6-7-day and 7-year-old rabbits is characterized by low neuron activity and inability to trace acquisition of rhythm. The pulse frequency and trace acquisition of the rhythm in animals aged 8-14 days and 4-5 years (middle age) formed slower than in adult animals (after 2-4 stimulation series on days 2-4 of experiment) and could not be reproduced on the next day without reminding. In rabbits aged 25-30 days and 1 year the basal activity reached the optimum level and trace acquisition of rhythm was observed after 1-2 series on days 1-2 of experiment and was reproduced without reminding on the next day. The detected physiological stages are in good correlation with the morphochemical organization of the rabbit hippocampus at the stages of early and late ontogeny.

  1. Restraint stress increases hemichannel activity in hippocampal glial cells and neurons.

    Science.gov (United States)

    Orellana, Juan A; Moraga-Amaro, Rodrigo; Díaz-Galarce, Raúl; Rojas, Sebastián; Maturana, Carola J; Stehberg, Jimmy; Sáez, Juan C

    2015-01-01

    Stress affects brain areas involved in learning and emotional responses, which may contribute in the development of cognitive deficits associated with major depression. These effects have been linked to glial cell activation, glutamate release and changes in neuronal plasticity and survival including atrophy of hippocampal apical dendrites, loss of synapses and neuronal death. Under neuro-inflammatory conditions, we recently unveiled a sequential activation of glial cells that release ATP and glutamate via hemichannels inducing neuronal death due to activation of neuronal NMDA/P2X7 receptors and pannexin1 hemichannels. In the present work, we studied if stress-induced glia activation is associated to changes in hemichannel activity. To this end, we compared hemichannel activity of brain cells after acute or chronic restraint stress in mice. Dye uptake experiments in hippocampal slices revealed that acute stress induces opening of both Cx43 and Panx1 hemichannels in astrocytes, which were further increased by chronic stress; whereas enhanced Panx1 hemichannel activity was detected in microglia and neurons after acute/chronic and chronic stress, respectively. Moreover, inhibition of NMDA/P2X7 receptors reduced the chronic stress-induced hemichannel opening, whereas blockade of Cx43 and Panx1 hemichannels fully reduced ATP and glutamate release in hippocampal slices from stressed mice. Thus, we propose that gliotransmitter release through hemichannels may participate in the pathogenesis of stress-associated psychiatric disorders and possibly depression.

  2. Restraint stress increases hemichannel activity in hippocampal glial cells and neurons

    Science.gov (United States)

    Orellana, Juan A.; Moraga-Amaro, Rodrigo; Díaz-Galarce, Raúl; Rojas, Sebastián; Maturana, Carola J.; Stehberg, Jimmy; Sáez, Juan C.

    2015-01-01

    Stress affects brain areas involved in learning and emotional responses, which may contribute in the development of cognitive deficits associated with major depression. These effects have been linked to glial cell activation, glutamate release and changes in neuronal plasticity and survival including atrophy of hippocampal apical dendrites, loss of synapses and neuronal death. Under neuro-inflammatory conditions, we recently unveiled a sequential activation of glial cells that release ATP and glutamate via hemichannels inducing neuronal death due to activation of neuronal NMDA/P2X7 receptors and pannexin1 hemichannels. In the present work, we studied if stress-induced glia activation is associated to changes in hemichannel activity. To this end, we compared hemichannel activity of brain cells after acute or chronic restraint stress in mice. Dye uptake experiments in hippocampal slices revealed that acute stress induces opening of both Cx43 and Panx1 hemichannels in astrocytes, which were further increased by chronic stress; whereas enhanced Panx1 hemichannel activity was detected in microglia and neurons after acute/chronic and chronic stress, respectively. Moreover, inhibition of NMDA/P2X7 receptors reduced the chronic stress-induced hemichannel opening, whereas blockade of Cx43 and Panx1 hemichannels fully reduced ATP and glutamate release in hippocampal slices from stressed mice. Thus, we propose that gliotransmitter release through hemichannels may participate in the pathogenesis of stress-associated psychiatric disorders and possibly depression. PMID:25883550

  3. Neuronal nitric oxide synthase contributes to pentylenetetrazole-kindling-induced hippocampal neurogenesis.

    Science.gov (United States)

    Zhu, Xinjian; Dong, Jingde; Shen, Kai; Bai, Ying; Chao, Jie; Yao, Honghong

    2016-03-01

    Neuronal nitric oxide synthase (nNOS), the major nitric oxide synthase isoform in the mammalian brain, is implicated in the pathophysiology of several neurological conditions, including epilepsy. Neurogenesis in hippocampal dentate gyrus (DG) persists throughout life in the adult brain. Alterations in this process occur in many neurological diseases, including epilepsy. Few studies, however, have addressed the role of nNOS in hippocampal DG neurogenesis in epileptic brain. The present study, therefore, investigated the role of nNOS in pentylenetetrazole (PTZ)-kindling-induced neurogenesis in hippocampal DG. Our results showed that nNOS expression and enzymatic activity were significantly increased in the hippocampus of PTZ-kindled mice. Meanwhile, these PTZ-kindled mice were characterized by significant enhancement of new born cells proliferation and survival in hippocampal DG, and these survived cells are co-labeled with NeuN and GFAP. Selective inhibition of nNOS by 7-NI, however, suppressed PTZ-kindling-induced hippocampal DG new born cells proliferation and survival, suggesting that nNOS contributes to PTZ-kindling-induced hippocampal neurogenesis. Copyright © 2016 Elsevier Inc. All rights reserved.

  4. Differential modulation of AMPA receptor mediated currents by Evans Blue in postnatal rat hippocampal neurones

    OpenAIRE

    Schürmann, Britta; Wu, Xueqing; Dietzel, Irmgard D; Leßmann, Volkmar

    1997-01-01

    The modulation of non-N-methyl-D-aspartate (NMDA) receptor-mediated whole cell currents and of glutamatergic synaptic transmission by purified Evans Blue (EB) was investigated in rat cultured postnatal hippocampal neurones by use of patch clamp recordings and a fast drug application system.Three different groups of neurones could be distinguished with respect to the type of modulation obtained with 10 μM EB: EB was either a predominant inhibitor of desensitization (13% of the neurones), a pre...

  5. Spatial learning depends on both the addition and removal of new hippocampal neurons.

    Directory of Open Access Journals (Sweden)

    David Dupret

    2007-08-01

    Full Text Available The role of adult hippocampal neurogenesis in spatial learning remains a matter of debate. Here, we show that spatial learning modifies neurogenesis by inducing a cascade of events that resembles the selective stabilization process characterizing development. Learning promotes survival of relatively mature neurons, apoptosis of more immature cells, and finally, proliferation of neural precursors. These are three interrelated events mediating learning. Thus, blocking apoptosis impairs memory and inhibits learning-induced cell survival and cell proliferation. In conclusion, during learning, similar to the selective stabilization process, neuronal networks are sculpted by a tightly regulated selection and suppression of different populations of newly born neurons.

  6. Diazinon and diazoxon impair the ability of astrocytes to foster neurite outgrowth in primary hippocampal neurons

    Energy Technology Data Exchange (ETDEWEB)

    Pizzurro, Daniella M.; Dao, Khoi [Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA (United States); Costa, Lucio G. [Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA (United States); Department of Neuroscience, University of Parma, Parma (Italy)

    2014-02-01

    Evidence from in vivo and epidemiological studies suggests that organophosphorus insecticides (OPs) are developmental neurotoxicants, but possible underlying mechanisms are still unclear. Astrocytes are increasingly recognized for their active role in normal neuronal development. This study sought to investigate whether the widely-used OP diazinon (DZ), and its oxygen metabolite diazoxon (DZO), would affect glial–neuronal interactions as a potential mechanism of developmental neurotoxicity. Specifically, we investigated the effects of DZ and DZO on the ability of astrocytes to foster neurite outgrowth in primary hippocampal neurons. The results show that both DZ and DZO adversely affect astrocyte function, resulting in inhibited neurite outgrowth in hippocampal neurons. This effect appears to be mediated by oxidative stress, as indicated by OP-induced increased reactive oxygen species production in astrocytes and prevention of neurite outgrowth inhibition by antioxidants. The concentrations of OPs were devoid of cytotoxicity, and cause limited acetylcholinesterase inhibition in astrocytes (18 and 25% for DZ and DZO, respectively). Among astrocytic neuritogenic factors, the most important one is the extracellular matrix protein fibronectin. DZ and DZO decreased levels of fibronectin in astrocytes, and this effect was also attenuated by antioxidants. Underscoring the importance of fibronectin in this context, adding exogenous fibronectin to the co-culture system successfully prevented inhibition of neurite outgrowth caused by DZ and DZO. These results indicate that DZ and DZO increase oxidative stress in astrocytes, and this in turn modulates astrocytic fibronectin, leading to impaired neurite outgrowth in hippocampal neurons. - Highlights: • DZ and DZO inhibit astrocyte-mediated neurite outgrowth in rat hippocampal neurons. • Oxidative stress is involved in inhibition of neuritogenesis by DZ and DZO. • DZ and DZO decrease expression of the neuritogenic

  7. Radix Puerariae modulates glutamatergic synaptic architecture and potentiates functional synaptic plasticity in primary hippocampal neurons.

    Science.gov (United States)

    Bhuiyan, Mohammad Maqueshudul Haque; Haque, Md Nazmul; Mohibbullah, Md; Kim, Yung Kyu; Moon, Il Soo

    2017-09-14

    Neurologic disorders are frequently characterized by synaptic pathology, including abnormal density and morphology of dendritic spines, synapse loss, and aberrant synaptic signaling and plasticity. Therefore, to promote and/or protect synapses by the use of natural molecules capable of modulating neurodevelopmental events, such as, spinogenesis and synaptic plasticity, could offer a preventive and curative strategy for nervous disorders associated with synaptic pathology. Radix Puerariae, the root of Pueraria monatana var. lobata (Willd.) Sanjappa&Pradeep, is a Chinese ethnomedicine, traditionally used for the treatment of memory-related nervous disorders including Alzheimer's disease. In the previous study, we showed that the ethanolic extracts of Radix Puerariae (RPE) and its prime constituent, puerarin induced neuritogenesis and synapse formation in cultured hippocampal neurons, and thus could improve memory functions. In the present study, we specifically investigated the abilities of RPE and puerarin to improve memory-related brain disorders through modulating synaptic maturation and functional potentiation. Rat embryonic (E19) brain neurons were cultured in the absence or presence of RPE or puerarin. At predetermined times, cells were live-stained with DiO or fixed and immunostained to visualize neuronal morphologies, or lysed for protein harvesting. Morphometric analyses of dendritic spines and synaptogenesis were performed using Image J software. Functional pre- and postsynaptic plasticity was measured by FM1-43 staining and whole-cell patch clamping, respectively. RPE or puerarin-mediated changes in actin-related protein 2 were assessed by Western blotting. Neuronal survivals were measured using propidium iodide exclusion assay. RPE and puerarin both: (1) promoted a significant increase in the numbers, and maturation, of dendritic spines; (2) modulated the formation of glutamatergic synapses; (3) potentiated synaptic transmission by increasing the sizes of

  8. Centella asiatica Attenuates Mitochondrial Dysfunction and Oxidative Stress in Aβ-Exposed Hippocampal Neurons

    Science.gov (United States)

    Zweig, Jonathan A.; Matthews, Donald G.; Caruso, Maya; Quinn, Joseph F.; Soumyanath, Amala

    2017-01-01

    Centella asiatica has been used for centuries to enhance memory. We have previously shown that a water extract of Centella asiatica (CAW) protects against the deleterious effects of amyloid-β (Aβ) in neuroblastoma cells and attenuates Aβ-induced cognitive deficits in mice. Yet, the neuroprotective mechanism of CAW has yet to be thoroughly explored in neurons from these animals. This study investigates the effects of CAW on neuronal metabolism and oxidative stress in isolated Aβ-expressing neurons. Hippocampal neurons from amyloid precursor protein overexpressing Tg2576 mice and wild-type (WT) littermates were treated with CAW. In both genotypes, CAW increased the expression of antioxidant response genes which attenuated the Aβ-induced elevations in reactive oxygen species (ROS) and lipid peroxidation in Tg2576 neurons. CAW also improved mitochondrial function in both genotypes and increased the expression of electron transport chain enzymes and mitochondrial labeling, suggesting an increase in mitochondrial content. These data show that CAW protects against mitochondrial dysfunction and oxidative stress in Aβ-exposed hippocampal neurons which could contribute to the beneficial effects of the extract observed in vivo. Since CAW also improved mitochondrial function in the absence of Aβ, these results suggest a broader utility for other conditions where neuronal mitochondrial dysfunction occurs. PMID:28883904

  9. EEA1 restores homeostatic synaptic plasticity in hippocampal neurons from Rett syndrome mice.

    Science.gov (United States)

    Xu, Xin; Pozzo-Miller, Lucas

    2017-08-15

    Rett syndrome is a neurodevelopmental disorder caused by loss-of-function mutations in MECP2, the gene encoding the transcriptional regulator methyl-CpG-binding protein 2 (MeCP2). Mecp2 deletion in mice results in an imbalance of excitation and inhibition in hippocampal neurons, which affects 'Hebbian' synaptic plasticity. We show that Mecp2-deficient neurons also lack homeostatic synaptic plasticity, likely due to reduced levels of EEA1, a protein involved in AMPA receptor endocytosis. Expression of EEA1 restored homeostatic synaptic plasticity in Mecp2-deficient neurons, providing novel targets of intervention in Rett syndrome. Rett syndrome is a neurodevelopmental disorder caused by loss-of-function mutations in MECP2, the gene encoding the transcriptional regulator methyl-CpG-binding protein 2 (MeCP2). Deletion of Mecp2 in mice results in an imbalance of synaptic excitation and inhibition in hippocampal pyramidal neurons, which affects 'Hebbian' long-term synaptic plasticity. Since the excitatory-inhibitory balance is maintained by homeostatic mechanisms, we examined the role of MeCP2 in homeostatic synaptic plasticity (HSP) at excitatory synapses. Negative feedback HSP, also known as synaptic scaling, maintains the global synaptic strength of individual neurons in response to sustained alterations in neuronal activity. Hippocampal neurons from Mecp2 knockout (KO) mice do not show the characteristic homeostatic scaling up of the amplitude of miniature excitatory postsynaptic currents (mEPSCs) and of synaptic levels of the GluA1 subunit of AMPA-type glutamate receptors after 48 h silencing with the Na + channel blocker tetrodotoxin. This deficit in HSP is bidirectional because Mecp2 KO neurons also failed to scale down mEPSC amplitudes and GluA1 synaptic levels after 48 h blockade of type A GABA receptor (GABA A R)-mediated inhibition with bicuculline. Consistent with the role of synaptic trafficking of AMPA-type of glutamate receptors in HSP, Mecp2 KO neurons

  10. Modelling the Somatic Electrical Response of Hippocampal Pyramidal Neurons

    Science.gov (United States)

    1989-09-01

    Computational Neuroscience Hippocampus Modelling 20. ABSTiRACT (Cetlin.a i oed* Ofe EU neeeeap ena IEWhEtDif by blook 0=maw) A modelling study of hippocampal...threshold. 3. A sleep activation) curve at the lower threshold taken with the non- zero inaclivation at depolarized membrane potentials would result in an...pmo ( (gap ot- hack tvtpane-eixin)) (defun startup () (tyake-window ’plot-frame 269 ,panes ’((*plot-pane-1 tv:plotter-pane :label *Voltages In Soma And

  11. Coexistence of Multiple Types of Synaptic Plasticity in Individual Hippocampal CA1 Pyramidal Neurons.

    Science.gov (United States)

    Edelmann, Elke; Cepeda-Prado, Efrain; Leßmann, Volkmar

    2017-01-01

    Understanding learning and memory mechanisms is an important goal in neuroscience. To gain insights into the underlying cellular mechanisms for memory formation, synaptic plasticity processes are studied with various techniques in different brain regions. A valid model to scrutinize different ways to enhance or decrease synaptic transmission is recording of long-term potentiation (LTP) or long-term depression (LTD). At the single cell level, spike timing-dependent plasticity (STDP) protocols have emerged as a powerful tool to investigate synaptic plasticity with stimulation paradigms that also likely occur during memory formation in vivo . Such kind of plasticity can be induced by different STDP paradigms with multiple repeat numbers and stimulation patterns. They subsequently recruit or activate different molecular pathways and neuromodulators for induction and expression of STDP. Dopamine (DA) and brain-derived neurotrophic factor (BDNF) have been recently shown to be important modulators for hippocampal STDP at Schaffer collateral (SC)-CA1 synapses and are activated exclusively by distinguishable STDP paradigms. Distinct types of parallel synaptic plasticity in a given neuron depend on specific subcellular molecular prerequisites. Since the basal and apical dendrites of CA1 pyramidal neurons are known to be heterogeneous, and distance-dependent dendritic gradients for specific receptors and ion channels are described, the dendrites might provide domain specific locations for multiple types of synaptic plasticity in the same neuron. In addition to the distinct signaling and expression mechanisms of various types of LTP and LTD, activation of these different types of plasticity might depend on background brain activity states. In this article, we will discuss some ideas why multiple forms of synaptic plasticity can simultaneously and independently coexist and can contribute so effectively to increasing the efficacy of memory storage and processing capacity of the

  12. Isolated primary blast alters neuronal function with minimal cell death in organotypic hippocampal slice cultures.

    Science.gov (United States)

    Effgen, Gwen B; Vogel, Edward W; Lynch, Kimberly A; Lobel, Ayelet; Hue, Christopher D; Meaney, David F; Bass, Cameron R Dale; Morrison, Barclay

    2014-07-01

    An increasing number of U.S. soldiers are diagnosed with traumatic brain injury (TBI) subsequent to exposure to blast. In the field, blast injury biomechanics are highly complex and multi-phasic. The pathobiology caused by exposure to some of these phases in isolation, such as penetrating or inertially driven injuries, has been investigated extensively. However, it is unclear whether the primary component of blast, a shock wave, is capable of causing pathology on its own. Previous in vivo studies in the rodent and pig have demonstrated that it is difficult to deliver a primary blast (i.e., shock wave only) without rapid head accelerations and potentially confounding effects of inertially driven TBI. We have previously developed a well-characterized shock tube and custom in vitro receiver for exposing organotypic hippocampal slice cultures to pure primary blast. In this study, isolated primary blast induced minimal hippocampal cell death (on average, below 14% in any region of interest), even for the most severe blasts tested (424 kPa peak pressure, 2.3 ms overpressure duration, and 248 kPa*ms impulse). In contrast, measures of neuronal function were significantly altered at much lower exposures (336 kPa, 0.84 ms, and 86.5 kPa*ms), indicating that functional changes occur at exposures below the threshold for cell death. This is the first study to investigate a tolerance for primary blast-induced brain cell death in response to a range of blast parameters and demonstrate functional deficits at subthreshold exposures for cell death.

  13. Hippocampal neuron firing and local field potentials in the in vitro 4-aminopyridine epilepsy model.

    Science.gov (United States)

    Gonzalez-Sulser, Alfredo; Wang, Jing; Queenan, Bridget N; Avoli, Massimo; Vicini, Stefano; Dzakpasu, Rhonda

    2012-11-01

    Excessive synchronous neuronal activity is a defining feature of epileptic activity. We previously characterized the properties of distinct glutamatergic and GABAergic transmission-dependent synchronous epileptiform discharges in mouse hippocampal slices using the 4-aminopyridine model of epilepsy. In the present study, we sought to identify the specific hippocampal neuronal populations that initiate and underlie these local field potentials (LFPs). A perforated multielectrode array was used to simultaneously record multiunit action potential firing and LFPs during spontaneous epileptiform activity. LFPs had distinct components based on the initiation site, extent of propagation, and pharmacological sensitivity. Individual units, located in different hippocampal subregions, fired action potentials during these LFPs. A specific neuron subgroup generated sustained action potential firing throughout the various components of the LFPs. The activity of this subgroup preceded the LFPs observed in the presence of antagonists of ionotropic glutamatergic synaptic transmission. In the absence of ionotropic glutamatergic and GABAergic transmission, LFPs disappeared, but units with shorter spike duration and high basal firing rates were still active. These spontaneously active units had an increased level of activity during LFPs and consistently preceded all LFPs recorded before blockade of synaptic transmission. Our findings reveal that neuronal subpopulations with interneuron properties are likely responsible for initiating synchronous activity in an in vitro model of epileptiform discharges.

  14. The Neuroprotective Effects of Carvacrol on Ethanol-Induced Hippocampal Neurons Impairment via the Antioxidative and Antiapoptotic Pathways

    Directory of Open Access Journals (Sweden)

    Peng Wang

    2017-01-01

    Full Text Available Chronic alcohol consumption causes hippocampal neuronal impairment, which is associated with oxidative stress and apoptosis. Carvacrol is a major monoterpenic phenol found in essential oils from the family Labiatae and has antioxidative stress and antiapoptosis actions. However, the protective effects of carvacrol in ethanol-induced hippocampal neuronal impairment have not been fully understood. We explored the neuroprotective effects of carvacrol in vivo and in vitro. Male C57BL/6 mice were exposed to 35% ethanol for 4 weeks to establish ethanol model in vivo, and hippocampal neuron injury was simulated by 200 mM ethanol in vitro. Morris water maze test was performed to evaluate the cognitive dysfunction. The oxidative stress injury of hippocampal neurons was evaluated by measuring the levels of oxidative stress biomarkers. Histopathological examinations and western blot were performed to evaluate the apoptosis of neurons. The results showed that carvacrol attenuates the cognitive dysfunction, oxidative stress, and apoptosis of the mice treated with ethanol and decreases hippocampal neurons apoptosis induced by ethanol in vitro. In addition, western blot analysis revealed that carvacrol modulates the protein expression of Bcl-2, Bax, caspase-3, and p-ERK, without influence of p-JNK and p-p38. Our results suggest that carvacrol alleviates ethanol-mediated hippocampal neuronal impairment by antioxidative and antiapoptotic effects.

  15. Carisbamate, a novel neuromodulator, inhibits voltage-gated sodium channels and action potential firing of rat hippocampal neurons.

    Science.gov (United States)

    Liu, Yi; Yohrling, George J; Wang, Yan; Hutchinson, Tasha L; Brenneman, Douglas E; Flores, Christopher M; Zhao, Boyu

    2009-01-01

    Carisbamate (RWJ-333369; (S)-2-O-carbamoyl-1-o-chlorophenyl-ethanol) is a novel investigational antiepileptic drug that exhibits a broad-spectrum of activity in a number of animal models of seizure and drug refractory epilepsy. In an effort to understand the molecular mechanism by which carisbamate produces its antiepileptic actions, we studied its effects on the function of voltage-gated, rat brain sodium and potassium channels and on the repetitive firing of action potentials in cultured rat hippocampal neurons. In whole-cell patch clamp recording, carisbamate resulted in a concentration-, voltage- and use-dependent inhibition of rat Nav1.2, with an IC(50) value of 68 microM at -67 mV. In rat hippocampal neurons, carisbamate similarly blocked voltage-gated sodium channels, with an IC(50) value of 89 microM at -67 mV, and inhibited repetitive firing of action potentials in a concentration-dependent manner (by 46% at 30 microM and 87% at 100 microM, respectively). Carisbamate had no effect on the steady-state membrane potential or voltage-gated potassium channels (K(v)) in these neurons. These inhibitory effects of carisbamate occurred at therapeutically relevant concentrations in vivo, raising the possibility that block of voltage-gated sodium channels by carisbamate contributes to its antiepileptic activity.

  16. 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.

  17. Evidence for Neuroprotective Effect of Sulbutiamine against Oxygen-Glucose Deprivation in Rat Hippocampal CA1 Pyramidal Neurons

    National Research Council Canada - National Science Library

    Jeehyun KWAGa; Aman Shah Abdul MAJIDb; c; Kui Dong KANGd

    2011-01-01

    .... Here we study the effect of sulbutiamine, a synthetic thiamine analogue that can cross the blood-brain barrier easily, on hippocampal neurons under an in vitro model of ischemia, oxygen-glucose deprivation (OGD...

  18. Knocking down of the KCC2 in rat hippocampal neurons increases intracellular chloride concentration and compromises neuronal survival

    Science.gov (United States)

    Pellegrino, Christophe; Gubkina, Olena; Schaefer, Michael; Becq, Hélène; Ludwig, Anastasia; Mukhtarov, Marat; Chudotvorova, Ilona; Corby, Severine; Salyha, Yuriy; Salozhin, Sergey; Bregestovski, Piotr; Medina, Igor

    2011-01-01

    Abstract KCC2 is a neuron-specific potassium–chloride co-transporter controlling intracellular chloride homeostasis in mature and developing neurons. It is implicated in the regulation of neuronal migration, dendrites outgrowth and formation of the excitatory and inhibitory synaptic connections. The function of KCC2 is suppressed under several pathological conditions including neuronal trauma, different types of epilepsies, axotomy of motoneurons, neuronal inflammations and ischaemic insults. However, it remains unclear how down-regulation of the KCC2 contributes to neuronal survival during and after toxic stress. Here we show that in primary hippocampal neuronal cultures the suppression of the KCC2 function using two different shRNAs, dominant-negative KCC2 mutant C568A or DIOA inhibitor, increased the intracellular chloride concentration [Cl−]i and enhanced the toxicity induced by lipofectamine-dependent oxidative stress or activation of the NMDA receptors. The rescuing of the KCC2 activity using over-expression of the active form of the KCC2, but not its non-active mutant Y1087D, effectively restored [Cl−]i and enhanced neuronal resistance to excitotoxicity. The reparative effects of KCC2 were mimicked by over-expression of the KCC3, a homologue transporter. These data suggest an important role of KCC2-dependent potassium/chloride homeostasis under neurototoxic conditions and reveal a novel role of endogenous KCC2 as a neuroprotective molecule. PMID:21486764

  19. Conditioned Medium Reconditions Hippocampal Neurons against Kainic Acid Induced Excitotoxicity: An In Vitro Study

    Directory of Open Access Journals (Sweden)

    Pradeep Kumar K. Bevinahal

    2014-01-01

    Full Text Available Stem cell therapy is gaining attention as a promising treatment option for neurodegenerative diseases. The functional efficacy of grafted cells is a matter of debate and the recent consensus is that the cellular and functional recoveries might be due to “by-stander” effects of grafted cells. In the present study, we investigated the neuroprotective effect of conditioned medium (CM derived from human embryonic kidney (HEK cells in a kainic acid (KA induced hippocampal degeneration model system in in vitro condition. Hippocampal cell line was exposed to KA (200 µM for 24 hrs (lesion group whereas, in the treatment group, hippocampal cell line was exposed to KA in combination with HEK-CM (KA + HEK-CM. We observed that KA exposure to cells resulted in significant neuronal loss. Interestingly, HEK-CM cotreatment completely attenuated the excitotoxic effects of KA. In HEK-CM cotreatment group, the cell viability was ~85–95% as opposed to 47% in KA alone group. Further investigation demonstrated that treatment with HEK-CM stimulated the endogenous cell survival factors like brain derived neurotrophic factors (BDNF and antiapoptotic factor Bcl-2, revealing the possible mechanism of neuroprotection. Our results suggest that HEK-CM protects hippocampal neurons against excitotoxicity by stimulating the host’s endogenous cell survival mechanisms.

  20. Hippocampal neuron populations are reduced in vervet monkeys with fetal alcohol exposure.

    Science.gov (United States)

    Burke, Mark W; Ptito, Maurice; Ervin, Frank R; Palmour, Roberta M

    2015-05-01

    Prenatal exposure to beverage alcohol is a major cause of mild mental retardation and developmental delay. In nonendangered alcohol-preferring vervet monkeys, we modeled the most common nondysmorphic form of fetal alcohol syndrome disorder with voluntary drinking during the third trimester of pregnancy. Here, we report significant numerical reductions in the principal hippocampal neurons of fetal alcohol-exposed (FAE) offspring, as compared to age-matched, similarly housed conspecifics with isocaloric sucrose exposure. These deficits, particularly marked in CA1 and CA3, are present neonatally and persist through infancy (5 months) and juvenile (2 years) stages. Although the volumes of hippocampal subdivisions in FAE animals are not atypical at birth, by age 2, they are only 65-70% of those estimated in age-matched controls. These data suggest that moderate, naturalistic alcohol consumption during late pregnancy results in a stable loss of hippocampal neurons and a progressive reduction of hippocampal volume. © 2015 The Authors. Developmental Psychobiology Published by Wiley Periodicals, Inc.

  1. Sleep deprivation and hippocampal vulnerability: changes in neuronal plasticity, neurogenesis and cognitive function.

    Science.gov (United States)

    Kreutzmann, J C; Havekes, R; Abel, T; Meerlo, P

    2015-11-19

    Despite the ongoing fundamental controversy about the physiological function of sleep, there is general consensus that sleep benefits neuronal plasticity, which ultimately supports brain function and cognition. In agreement with this are numerous studies showing that sleep deprivation (SD) results in learning and memory impairments. Interestingly, such impairments appear to occur particularly when these learning and memory processes require the hippocampus, suggesting that this brain region may be particularly sensitive to the consequences of sleep loss. Although the molecular mechanisms underlying sleep and memory formation remain to be investigated, available evidence suggests that SD may impair hippocampal neuronal plasticity and memory processes by attenuating intracellular cyclic adenosine monophosphate (cAMP)-protein kinase A (PKA) signaling which may lead to alterations in cAMP response element binding protein (CREB)-mediated gene transcription, neurotrophic signaling, and glutamate receptor expression. When restricted sleep becomes a chronic condition, it causes a reduction of hippocampal cell proliferation and neurogenesis, which may eventually lead to a reduction in hippocampal volume. Ultimately, by impairing hippocampal plasticity and function, chronically restricted and disrupted sleep contributes to cognitive disorders and psychiatric diseases. Copyright © 2015 IBRO. Published by Elsevier Ltd. All rights reserved.

  2. Interleukin-1β increases neuronal death in the hippocampal dentate gyrus associated with status epilepticus in the developing rat.

    Science.gov (United States)

    Rincón-López, C; Tlapa-Pale, A; Medel-Matus, J-S; Martínez-Quiroz, J; Rodríguez-Landa, J F; López-Meraz, M-L

    Interleukin-1β (IL-1β) increases necrotic neuronal cell death in the CA1 area after induced status epilepticus (SE) in developing rats. However, it remains uncertain whether IL-1β has a similar effect on the hippocampal dentate gyrus (DG). In this study, we analysed the effects of IL-1β on 14-day-old Wistar rats experiencing DG neuronal death induced by SE. SE was induced with lithium-pilocarpine. Six hours after SE onset, a group of pups was injected with IL-1β (at 0, 0.3, 3, 30, or 300ng/μL) in the right ventricle; another group was injected with IL-1β receptor (IL-1R1) antagonist (IL-1Ra, at 30ng/μL) of IL-1RI antagonist (IL-1Ra) alone, and additional group with 30ng/μL of IL-1Ra plus 3ng/μL of IL-1β. Twenty-four hours after SE onset, neuronal cell death in the dentate gyrus of the dorsal hippocampus was assessed using haematoxylin-eosin staining. Dead cells showed eosinophilic cytoplasm and condensed and fragmented nuclei. We observed an increased number of eosinophilic cells in the hippocampal DG ipsilateral to the site of injection of 3ng/μL and 300ng/μL of IL-1β in comparison with the vehicle group. A similar effect was observed in the hippocampal DG contralateral to the site of injection of 3ng/μL of IL-1β. Administration of both of IL-1β and IL-1Ra failed to prevent an increase in the number of eosinophilic cells. Our data suggest that IL-1β increases apoptotic neuronal cell death caused by SE in the hippocampal GD, which is a mechanism independent of IL-1RI activation. Copyright © 2016 Sociedad Española de Neurología. Publicado por Elsevier España, S.L.U. All rights reserved.

  3. The neuritogenic and synaptogenic effects of the ethanolic extract of radix Puerariae in cultured rat hippocampal neurons.

    Science.gov (United States)

    Haque Bhuiyan, Mohammad Maqueshudul; Mohibbullah, Md; Hannan, Md Abdul; Hong, Yong-Ki; Han, Chang-Ho; Kim, Yung Kyu; Moon, Il Soo

    2015-09-15

    Radix Puerariae, the root of Pueraria montana var. lobata (Willd.) Sanjappa & Pradeep, is used in Korean traditional medicine to treat neuronal disorders including Parkinson's disease, and its active constituent, puerarin has been reported to have a neuroprotective effect in experimental models of Parkinson's and Alzheimer's disease. To investigate the neurotrophic effects of these ethnomedicines on the development of central nervous system neurons and the molecular bases of these activities. Rat embryonic (E19) brain neurons were cultured in the absence or presence of the ethanolic extract of Radix Puerariae (RPE) or puerarin. At predetermined times, cells were fixed and immunostained to visualize neuronal morphologies, or lysed for protein harvesting. Morphometric analyses of neurite outgrowths and synaptogenesis were performed using Image J software. RPE or puerarin-mediated changes in the protein profiles of cultured neurons were assessed by MALDI-TOF-MS/PMF and measuring immunofluorescent intensities. RPE and puerarin alone promoted maximum neurite outgrowths at concentrations of 1µg/ml and 5µM, respectively. At these optimal concentrations, RPE and puerarin provided neurotrophic support by promoting axo-dendritic arbors and synapse formation in cultured neurons. Proteomic study revealed that RPE and puerarin both up-regulated a number of proteins, including dynein light chain 2 (DLC2) and elongation factor 2 (EF2), which are associated with neuritogenesis and synaptic potentiation, respectively. Immunofluorescence intensity measurements confirmed the expressions of the DLC2 and Dync1h1 subunits of dynein in RPE or puerarin treated hippocampal neurons were up-regulated when RPE or puerarin induced changes in neuronal cytoarchitecture. Our study demonstrates that RPE and puerarin should be considered potentially valuable preventative therapeutics for brain disorders due to their abilities to promote the neuronal cytoarchitecture and the synaptic functionality

  4. Amyloid-Beta Induced Changes in Vesicular Transport of BDNF in Hippocampal Neurons

    OpenAIRE

    Seifert, Bianca; Eckenstaler, Robert; R?nicke, Raik; Leschik, Julia; Lutz, Beat; Reymann, Klaus; Lessmann, Volkmar; Brigadski, Tanja

    2016-01-01

    The neurotrophin brain derived neurotrophic factor (BDNF) is an important growth factor in the CNS. Deficits in transport of this secretory protein could underlie neurodegenerative diseases. Investigation of disease-related changes in BDNF transport might provide insights into the cellular mechanism underlying, for example, Alzheimer’s disease (AD). To analyze the role of BDNF transport in AD, live cell imaging of fluorescently labeled BDNF was performed in hippocampal neurons of different AD...

  5. Cyclothiazide induces robust epileptiform activity in rat hippocampal neurons both in vitro and in vivo.

    Science.gov (United States)

    Qi, Jinshun; Wang, Yun; Jiang, Min; Warren, Philippa; Chen, Gong

    2006-03-15

    Cyclothiazide (CTZ) is a potent blocker of AMPA receptor desensitization. We have recently demonstrated that CTZ also inhibits GABA(A) receptors. Here we report that CTZ induces robust epileptiform activity in hippocampal neurons both in vitro and in vivo. We first found that chronic treatment of hippocampal cultures with CTZ (5 microM, 48 h) results in epileptiform activity in the majority of neurons (80%). The epileptiform activity lasts more than 48 h after washing off CTZ, suggesting a permanent change of the neural network properties after CTZ treatment. We then demonstrated in in vivo recordings that injection of CTZ (5 micromol in 5 microl) into the lateral ventricles of anaesthetized rats also induces spontaneous epileptiform activity in the hippocampal CA1 region. The epileptogenic effect of CTZ is probably due to its enhancing glutamatergic neurotransmission as shown by increasing the frequency and decay time of mEPSCs, and simultaneously inhibiting GABAergic neurotransmission by reducing the frequency of mIPSCs. Comparing to a well-known epileptogenic agent kainic acid (KA), CTZ affects neuronal activity mainly through modulating synaptic transmission without significant change of the intrinsic membrane excitability. Unlike KA, which induces significant cell death in hippocampal cultures, CTZ treatment does not result in any apparent neuronal death. Therefore, the CTZ-induced epilepsy model may provide a novel research tool to elucidate the molecular and cellular mechanisms of epileptogenesis without any complication from drug-induced cell death. The long-lasting epileptiform activity after CTZ washout may also make it a very useful model in screening antiepileptic drugs.

  6. Arrested neuronal proliferation and impaired hippocampal function following fractionated brain irradiation in the adult rat

    DEFF Research Database (Denmark)

    Madsen, Torsten Meldgaard; Kristjansen, P.E.G.; Bolwig, Tom Gert

    2003-01-01

    irradiation blocked the formation of new neurons in the dentate gyrus of the hippocampus. At different time points after the termination of the irradiation procedure, the animals were tested in two tests of short-term memory that differ with respect to their dependence on hippocampal function. Eight and 21...... that blocked neurogenesis contributes to the reported deleterious side effects of this treatment, consisting of memory impairment, dysphoria and lethargy....

  7. Primary cilia modulate TLR4-mediated inflammatory responses in hippocampal neurons.

    Science.gov (United States)

    Baek, Hyunjung; Shin, Hyo Jung; Kim, Jwa-Jin; Shin, Nara; Kim, Sena; Yi, Min-Hee; Zhang, Enji; Hong, Jinpyo; Kang, Joon Won; Kim, Yonghyun; Kim, Cuk-Seong; Kim, Dong Woon

    2017-09-19

    The primary cilium is an organelle that can act as a master regulator of cellular signaling. Despite the presence of primary cilia in hippocampal neurons, their function is not fully understood. Recent studies have demonstrated that the primary cilium influences interleukin (IL)-1β-induced NF-κB signaling, ultimately mediating the inflammatory response. We, therefore, investigated ciliary function and NF-κB signaling in lipopolysaccharide (LPS)-induced neuroinflammation in conjunction with ciliary length analysis. Since TLR4/NF-κB signaling is a well-known inflammatory pathway, we measured ciliary length and inflammatory mediators in wild type (WT) and TLR4-/- mice injected with LPS. Next, to exclude the effects of microglial TLR4, we examined the ciliary length, ciliary components, inflammatory cytokine, and mediators in HT22 hippocampal neuronal cells. Primary ciliary length decreased in hippocampal pyramidal neurons after intracerebroventricular injection of LPS in WT mice, whereas it increased in TLR4-/- mice. LPS treatment decreased primary ciliary length, activated NF-κB signaling, and increased Cox2 and iNOS levels in HT22 hippocampal neurons. In contrast, silencing Kif3a, a key protein component of cilia, increased ARL13B ciliary protein levels and suppressed NF-κB signaling and expression of inflammatory mediators. These data suggest that LPS-induced NF-κB signaling and inflammatory mediator expression are modulated by cilia and that the blockade of primary cilium formation by Kif3a siRNA regulates TLR4-induced NF-κB signaling. We propose that primary cilia are critical for regulating NF-κB signaling events in neuroinflammation and in the innate immune response.

  8. Effects of huperzine A on acute hypobaric hypoxic-induced apoptosis of hippocampal neurons in rats

    Directory of Open Access Journals (Sweden)

    Qing-hai SHI

    2013-02-01

    Full Text Available Objective  To investigate the effects of huperzine A on ameliorating acute hypobaric hypoxic-induced spatial learning and memory deficits, and on relieving the apoptosis of hippocampal neurons in rats. Methods  Forty-eight SD rats were randomly divided into four groups (12 each: the champaign (plain group (control group, champaign+huperzine A group, high altitude group (simulated 6000m plateau and high altitude+huperzine A group. One day before the decompression simulation experiment, rats in huperzine A-treated groups were given intragastrically with huperzine A suspension (10mg/ml in a dose of 0.1mg/kg. The spatial learning and memory performance of rats in each group were tested by Morris Water Maze. The apoptosis of hippocampal neurons was determined by TUNEL. The expression of pro-apoptotic proteins (Bax and anti-apoptotic protein (Bcl2 of hippocampus tissues were evaluated by Western blotting. Results  Compared with those in high altitude group, significantly shortened escape latency (P<0.05, more platform crossing within 60s (P<0.05, longer retention time in target (P<0.05, lower rate of hippocampal neurons apoptosis (P<0.05, down-regulated expression of Bax (P<0.05 and up-regulated expression of Bcl2(P<0.05 in the hippocampus tissues were found in the high altitude+huperzine A group. However, no significant difference in the above mentioned findings was found between high altitude+huperzine A group and champaign control group. Conclusion  Huperzine A treatment may have a protective effect against acute hypobaric hypoxic-induced apoptosis of hippocampal neurons in rats, and it ameliorates spatial learning and memory deficits in rats.

  9. Dietary cholesterol concentration affects synaptic plasticity and dendrite spine morphology of rabbit hippocampal neurons.

    Science.gov (United States)

    Wang, Desheng; Zheng, Wen

    2015-10-05

    Previous studies have shown dietary cholesterol can enhance learning but retard memory which may be partly due to increased cholesterol levels in hippocampus and reduced afterhyperpolarization (AHP) amplitude of hippocampal CA1 neurons. This study explored the dose-dependent effect of dietary cholesterol on synaptic plasticity of rabbit hippocampal CA1 neurons and spine morphology, the postsynaptic structures responsible for synaptic plasticity. Field potential recordings revealed a low concentration of dietary cholesterol increased long-term potentiation (LTP) expression while high concentrations produced a pronounced reduction in LTP expression. Dietary cholesterol facilitated basal synaptic transmission but did not influence presynaptic function. DiI staining showed dietary cholesterol induced alterations in dendrite spine morphology characterized by increased mushroom spine density and decreased thin spine density, two kinds of dendritic spines that may be linked to memory consolidation and learning acquisition. Dietary cholesterol also modulated the geometric measures of mushroom spines. Therefore, dietary cholesterol dose-dependently modulated both synaptic plasticity and dendrite spine morphologies of hippocampal CA1 neurons that could mediate learning and memory changes previously seen to result from feeding a cholesterol diet. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Anti-inflammatory effects of Ginkgo biloba extract against trimethyltin-induced hippocampal neuronal injury.

    Science.gov (United States)

    Kaur, Sukhwinder; Sharma, Neha; Nehru, Bimla

    2018-02-01

    Despite the immense neuromodulatory potentials of Ginkgo biloba extract as a memory enhancer, its underlying mechanism seems inadequate particularly with regard to its anti-inflammatory properties. The objective of the present study is to investigate the protective potentials of Ginkgo biloba extract (GBE) against hippocampal neuronal injury induced by trimethyltin (TMT), a potent neurotoxicant. Male SD rats were administered trimethyltin (8.5 mg kg -1 b.wt) single intraperitoneal (i.p.) injection, followed by Ginkgo biloba extract (100 mg kg -1 b.wt i.p) for 21 days. The co-administration of GBE with TMT showed marked improvement in cognitive functions. Concomitantly, there was a significant decrease in oxidative stress as evident by reduction in MDA and total ROS levels. In addition, there was a marked suppression of astrocyte activation (GFAP), transcription factor NFκB and proinflammatory cytokines (TNF-α, IL-1α, 1L-6), which were found to be elevated by TMT administration. Histopathological observations showed remarkable improvement in hippocampal neuronal injury in the conjunctive group. Therefore, it is suggested that Ginkgo biloba extract is an effective agent against trimethyltin-induced hippocampal neuronal loss owing to its antioxidative as well as anti-inflammatory properties.

  11. A viral vector expressing hypoxia-inducible factor 1 alpha inhibits hippocampal neuronal apoptosis

    OpenAIRE

    Chai, Xiqing; Kong, Weina; Liu, Lingyun; Yu, Wenguo; Zhang, Zhenqing; Sun, Yimin

    2014-01-01

    Hypoxia-inducible factor 1 (HIF-1) attenuates amyloid-beta protein neurotoxicity and decreases apoptosis induced by oxidative stress or hypoxia in cortical neurons. In this study, we constructed a recombinant adeno-associated virus (rAAV) vector expressing the human HIF-1α gene (rAAV-HIF-1α), and tested the assumption that rAAV-HIF-1α represses hippocampal neuronal apoptosis induced by amyloid-beta protein. Our results confirmed that rAAV-HIF-1α significantly reduces apoptosis induced by amyl...

  12. Distinct epigenetic and gene expression changes in rat hippocampal neurons after Morris water maze training

    Directory of Open Access Journals (Sweden)

    Sylvia D. eCarter

    2015-06-01

    Full Text Available Gene transcription and translation in the hippocampus is of critical importance in hippocampus-dependent memory formation, including during Morris water maze (MWM learning. Previous work using gene deletion models has shown that the immediate-early genes (IEGs c-Fos, Egr-1 and Arc are crucial for such learning. Recently, we reported that induction of IEGs in sparse dentate gyrus neurons requires ERK MAPK signaling and downstream formation of a distinct epigenetic histone mark (i.e. phospho-acetylated histone H3. Until now, this signaling, epigenetic and gene transcriptional pathway has not been comprehensively studied in the MWM model. Therefore, we conducted a detailed study of the phosphorylation of ERK1/2 and serine10 in histone H3 (H3S10p and induction of IEGs in the hippocampus of MWM trained rats and matched controls. MWM training evoked consecutive waves of ERK1/2 phosphorylation and H3S10 phosphorylation, as well as c-Fos, Egr-1 and Arc induction in sparse hippocampal neurons. The observed effects were most pronounced in the dentate gyrus. A positive correlation was found between the average latency to find the platform and the number of H3S10p-positive dentate gyrus neurons. Furthermore, chromatin immuno-precipitation (ChIP revealed a significantly increased association of phospho-acetylated histone H3 (H3K9ac-S10p with the gene promoters of c-Fos and Egr-1, but not Arc, after MWM exposure compared with controls. Surprisingly, however, we found very little difference between IEG responses (regarding both protein and mRNA in MWM-trained rats compared with matched swim controls. We conclude that exposure to the water maze evokes ERK MAPK activation, distinct epigenetic changes and IEG induction predominantly in sparse dentate gyrus neurons. It appears, however, that a specific role for IEGs in the learning aspect of MWM training may become apparent in downstream AP-1- and Egr-1-regulated (second wave genes and Arc-dependent effector

  13. Early Transcriptional Changes Induced by Wnt/β-Catenin Signaling in Hippocampal Neurons

    Directory of Open Access Journals (Sweden)

    Eduardo Pérez-Palma

    2016-01-01

    Full Text Available Wnt/β-catenin signaling modulates brain development and function and its deregulation underlies pathological changes occurring in neurodegenerative and neurodevelopmental disorders. Since one of the main effects of Wnt/β-catenin signaling is the modulation of target genes, in the present work we examined global transcriptional changes induced by short-term Wnt3a treatment (4 h in primary cultures of rat hippocampal neurons. RNAseq experiments allowed the identification of 170 differentially expressed genes, including known Wnt/β-catenin target genes such as Notum, Axin2, and Lef1, as well as novel potential candidates Fam84a, Stk32a, and Itga9. Main biological processes enriched with differentially expressed genes included neural precursor (GO:0061364, p-adjusted = 2.5 × 10−7, forebrain development (GO:0030900, p-adjusted = 7.3 × 10−7, and stem cell differentiation (GO:0048863 p-adjusted = 7.3 × 10−7. Likewise, following activation of the signaling cascade, the expression of a significant number of genes with transcription factor activity (GO:0043565, p-adjusted = 4.1 × 10−6 was induced. We also studied molecular networks enriched upon Wnt3a activation and detected three highly significant expression modules involved in glycerolipid metabolic process (GO:0046486, p-adjusted = 4.5 × 10−19, learning or memory (GO:0007611, p-adjusted = 4.0 × 10−5, and neurotransmitter secretion (GO:0007269, p-adjusted = 5.3 × 10−12. Our results indicate that Wnt/β-catenin mediated transcription controls multiple biological processes related to neuronal structure and activity that are affected in synaptic dysfunction disorders.

  14. Altered neuronal excitability underlies impaired hippocampal function in an animal model of psychosis

    Directory of Open Access Journals (Sweden)

    Thomas eGrüter

    2015-05-01

    Full Text Available Psychosis is accompanied by severe attentional deficits, and impairments in associational-memory processing and sensory information processing that are ascribed to dysfunctions in prefrontal and hippocampal function. Disruptions of glutamatergic signalling may underlie these alterations: Antagonism of the N-methyl-D-aspartate receptor (NMDAR results in similar molecular, cellular, cognitive and behavioural changes in rodents and/or humans as those that occur in psychosis, raising the question as to whether changes in glutamatergic transmission may be intrinsic to the pathophysiology of the disease. In an animal model of psychosis that comprises treatment with the irreversible NMDAR-antagonist, MK801, we explored the cellular mechanisms that may underlie hippocampal dysfunction in psychosis. MK801-treatment resulted in a profound loss of hippocampal LTP that was evident 4 weeks after treatment. Whereas neuronal expression of the immediate early gene, Arc, was enhanced in the hippocampus by spatial learning in controls, MK801-treated animals failed to show activity-dependent increases in Arc expression. By contrast, a significant increase in basal Arc expression in the absence of learning was evident compared to controls. Paired-pulse facilitation was increased at the 40 ms interval indicating that NMDAR and/or fast GABAergic-mediated neurotransmission was disrupted. In line with this, MK801-treatment resulted in a significant decrease in GABA(A, and increase in GABA(B-receptor-expression in PFC, along with a significant increase of GABA(B- and NMDAR-GluN2B expression in the dentate gyrus. NMDAR-GluN1 or GluN2A subunit expression was unchanged. These data suggest that in psychosis, deficits in hippocampus-dependent memory may be caused by a loss of hippocampal LTP that arises through enhanced hippocampal neuronal excitability, altered GluN2B and GABA receptor expression and an uncoupling of the hippocampus-prefrontal cortex circuitry.

  15. Cdk5 Is Essential for Amphetamine to Increase Dendritic Spine Density in Hippocampal Pyramidal Neurons

    Directory of Open Access Journals (Sweden)

    Soledad Ferreras

    2017-11-01

    Full Text Available Psychostimulant drugs of abuse increase dendritic spine density in reward centers of the brain. However, little is known about their effects in the hippocampus, where activity-dependent changes in the density of dendritic spine are associated with learning and memory. Recent reports suggest that Cdk5 plays an important role in drug addiction, but its role in psychostimulant’s effects on dendritic spines in hippocampus remain unknown. We used in vivo and in vitro approaches to demonstrate that amphetamine increases dendritic spine density in pyramidal neurons of the hippocampus. Primary cultures and organotypic slice cultures were used for cellular, molecular, pharmacological and biochemical analyses of the role of Cdk5/p25 in amphetamine-induced dendritic spine formation. Amphetamine (two-injection protocol increased dendritic spine density in hippocampal neurons of thy1-green fluorescent protein (GFP mice, as well as in hippocampal cultured neurons and organotypic slice cultures. Either genetic or pharmacological inhibition of Cdk5 activity prevented the amphetamine–induced increase in dendritic spine density. Amphetamine also increased spine density in neurons overexpressing the strong Cdk5 activator p25. Finally, inhibition of calpain, the protease necessary for the conversion of p35 to p25, prevented amphetamine’s effect on dendritic spine density. We demonstrate, for the first time, that amphetamine increases the density of dendritic spine in hippocampal pyramidal neurons in vivo and in vitro. Moreover, we show that the Cdk5/p25 signaling and calpain activity are both necessary for the effect of amphetamine on dendritic spine density. The identification of molecular mechanisms underlying psychostimulant effects provides novel and promising therapeutic approaches for the treatment of drug addiction.

  16. Neuroprotective effects of ischemic preconditioning on hippocampal CA1 pyramidal neurons through maintaining calbindin D28k immunoreactivity following subsequent transient cerebral ischemia.

    Science.gov (United States)

    Kim, In Hye; Jeon, Yong Hwan; Lee, Tae-Kyeong; Cho, Jeong Hwi; Lee, Jae-Chul; Park, Joon Ha; Ahn, Ji Hyeon; Shin, Bich-Na; Kim, Yang Hee; Hong, Seongkweon; Yan, Bing Chun; Won, Moo-Ho; Lee, Yun Lyul

    2017-06-01

    Ischemic preconditioning elicited by a non-fatal brief occlusion of blood flow has been applied for an experimental therapeutic strategy against a subsequent fatal ischemic insult. In this study, we investigated the neuroprotective effects of ischemic preconditioning (2-minute transient cerebral ischemia) on calbindin D28k immunoreactivity in the gerbil hippocampal CA1 area following a subsequent fatal transient ischemic insult (5-minute transient cerebral ischemia). A large number of pyramidal neurons in the hippocampal CA1 area died 4 days after 5-minute transient cerebral ischemia. Ischemic preconditioning reduced the death of pyramidal neurons in the hippocampal CA1 area. Calbindin D28k immunoreactivity was greatly attenuated at 2 days after 5-minute transient cerebral ischemia and it was hardly detected at 5 days post-ischemia. Ischemic preconditioning maintained calbindin D28k immunoreactivity after transient cerebral ischemia. These findings suggest that ischemic preconditioning can attenuate transient cerebral ischemia-caused damage to the pyramidal neurons in the hippocampal CA1 area through maintaining calbindin D28k immunoreactivity.

  17. SoxC Transcription Factors Are Required for Neuronal Differentiation in Adult Hippocampal Neurogenesis

    Science.gov (United States)

    Mu, Lifang; Berti, Lucia; Masserdotti, Giacomo; Covic, Marcela; Michaelidis, Theologos M.; Doberauer, Kathrin; Merz, Katharina; Rehfeld, Frederick; Haslinger, Anja; Wegner, Michael; Sock, Elisabeth; Lefebvre, Veronique; Couillard-Despres, Sebastien; Aigner, Ludwig; Berninger, Benedikt; Lie, D. Chichung

    2012-01-01

    Neural stem cells (NSCs) generate new hippocampal dentate granule neurons throughout adulthood. The genetic programs controlling neuronal differentiation of adult NSCs are only poorly understood. Here we show that, in the adult mouse hippocampus, expression of the SoxC transcription factors Sox4 and Sox11 is initiated around the time of neuronal commitment of adult NSCs and is maintained in immature neurons. Overexpression of Sox4 and Sox11 strongly promotes in vitro neurogenesis from adult NSCs, whereas ablation of Sox4/Sox11 prevents in vitro and in vivo neurogenesis from adult NSCs. Moreover, we demonstrate that SoxC transcription factors target the promoters of genes that are induced on neuronal differentiation of adult NSCs. Finally, we show that reprogramming of astroglia into neurons is dependent on the presence of SoxC factors. These data identify SoxC proteins as essential contributors to the genetic network controlling neuronal differentiation in adult neurogenesis and neuronal reprogramming of somatic cells. PMID:22378879

  18. The hippocampus of the eastern rock sengi: cytoarchitecture, markers of neuronal function, principal cell numbers and adult neurogenesis

    Directory of Open Access Journals (Sweden)

    Lutz eSlomianka

    2013-10-01

    Full Text Available The brains of sengis (elephant shrews, order Macroscelidae have long been known to contain a hippocampus that in terms of allometric progression indices is larger than that of most primates and equal in size to that of humans. In this report, we provide descriptions of hippocampal cytoarchitecture in the eastern rock sengi (Elephantulus myurus, of the distributions of hippocampal calretinin, calbindin, parvalbumin and somatostatin, of principal neuron numbers and of cell numbers related to proliferation and neuronal differentiation in adult hippocampal neurogenesis. Sengi hippocampal cytoarchitecture is an amalgamation of characters that are found in CA1 of, e.g., guinea pig and rabbits and in CA3 and dentate gyrus of primates. Correspondence analysis of total cell numbers and quantitative relations between principal cell populations relate this sengi to macaque monkeys and domestic pigs, and distinguish the sengi from distinct patterns of relations found in humans, dogs and murine rodents. Calretinin and calbindin are present in some cell populations that also express these proteins in other species, e.g., interneurons at the stratum oriens/alveus border or temporal hilar mossy cells, but neurons expressing these markers are often scarce or absent in other layers. The distributions of parvalbumin and somatostatin resemble those in other species. Normalized numbers of PCNA+ proliferating cells and doublecortin+ differentiating cells of neuronal lineage fall within the overall ranges of murid rodents, but differed from three murid species captured in the same habitat in that fewer doublecortin+ cells relative to PCNA+ were observed . The large and well-differentiated sengi hippocampus is not accompanied by correspondingly sized cortical and subcortical limbic areas that are the main hippocampal sources of afferents and targets of efferents. This points to intrinsic hippocampal information processing as the selective advantage of the large sengi

  19. Reduction of Cav1.3 channels in dorsal hippocampus impairs the development of dentate gyrus newborn neurons and hippocampal-dependent memory tasks.

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    Su-Hyun Kim

    Full Text Available Cav1.3 has been suggested to mediate hippocampal neurogenesis of adult mice and contribute to hippocampal-dependent learning and memory processes. However, the mechanism of Cav1.3 contribution in these processes is unclear. Here, roles of Cav1.3 of mouse dorsal hippocampus during newborn cell development were examined. We find that knock-out (KO of Cav1.3 resulted in the reduction of survival of newborn neurons at 28 days old after mitosis. The retroviral eGFP expression showed that both dendritic complexity and the number and length of mossy fiber bouton (MFB filopodia of newborn neurons at ≥ 14 days old were significantly reduced in KO mice. Both contextual fear conditioning (CFC and object-location recognition tasks were impaired in recent (1 day memory test while passive avoidance task was impaired only in remote (≥ 20 days memory in KO mice. Results using adeno-associated virus (AAV-mediated Cav1.3 knock-down (KD or retrovirus-mediated KD in dorsal hippocampal DG area showed that the recent memory of CFC was impaired in both KD mice but the remote memory was impaired only in AAV KD mice, suggesting that Cav1.3 of mature neurons play important roles in both recent and remote CFC memory while Cav1.3 in newborn neurons is selectively involved in the recent CFC memory process. Meanwhile, AAV KD of Cav1.3 in ventral hippocampal area has no effect on the recent CFC memory. In conclusion, the results suggest that Cav1.3 in newborn neurons of dorsal hippocampus is involved in the survival of newborn neurons while mediating developments of dendritic and axonal processes of newborn cells and plays a role in the memory process differentially depending on the stage of maturation and the type of learning task.

  20. MADP, a salidroside analog, protects hippocampal neurons from glutamate induced apoptosis.

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    Xian, Hua; Zhao, Jing; Zheng, Yuan; Wang, Meihong; Huang, Jun; Wu, Bingxin; Sun, Cheng; Yang, Yumin

    2014-05-08

    To investigate the anti-apoptotic effect of MADP, an analog of salidroside, against glutamate induced apoptosis in the cultured rat hippocampal neurons. Cytotoxicity was determined by the MTT method and lactate dehydrogenase release to the medium. Cell apoptosis was evaluated by Hoechst 33342 staining, TUNEL assay and flow cytometric analysis. Western blotting was applied for detecting protein levels of cellular signaling molecules. Our results showed that glutamate exposure significantly induces cell apoptosis, whereas the pretreatment of salidroside or MADP remarkably improves cell viability. Most importantly, the anti-apoptotic effect of MADP against glutamate insult is superior to salidroside. To explore the involved mechanisms, we measured some pro-apoptotic and anti-apoptotic protein levels, and several cell survival signaling pathways were analyzed as well. No visible alterations in Bcl-2 and Bax protein levels were observed by MADP or salidroside. Akt and JNK phosphorylation was robustly stimulated by MADP in the glutamate-treated neurons. Salidroside treatment results in a slight activation in Akt, while no significant alteration in JNK activity was observed. MADP exhibits higher capacity to attenuate glutamate induced cell apoptosis in the cultured rat hippocampal neurons, suggesting that MADP might be a better candidate than salidroside for developing novel drugs treating neuron loss associated disorders. Copyright © 2014 Elsevier Inc. All rights reserved.

  1. Network mechanisms of theta related neuronal activity in hippocampal CA1 pyramidal neurons.

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    Losonczy, Attila; Zemelman, Boris V; Vaziri, Alipasha; Magee, Jeffrey C

    2010-08-01

    Although hippocampal theta oscillations represent a prime example of temporal coding in the mammalian brain, little is known about the specific biophysical mechanisms. Intracellular recordings support a particular abstract oscillatory interference model of hippocampal theta activity, the soma-dendrite interference model. To gain insight into the cellular and circuit level mechanisms of theta activity, we implemented a similar form of interference using the actual hippocampal network in mice in vitro. We found that pairing increasing levels of phasic dendritic excitation with phasic stimulation of perisomatic projecting inhibitory interneurons induced a somatic polarization and action potential timing profile that reproduced most common features. Alterations in the temporal profile of inhibition were required to fully capture all features. These data suggest that theta-related place cell activity is generated through an interaction between a phasic dendritic excitation and a phasic perisomatic shunting inhibition delivered by interneurons, a subset of which undergo activity-dependent presynaptic modulation.

  2. Glutamatergic neurons of the mouse medial septum and diagonal band of Broca synaptically drive hippocampal pyramidal cells: relevance for hippocampal theta rhythm.

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    Huh, Carey Y L; Goutagny, Romain; Williams, Sylvain

    2010-11-24

    Neurons of the medial septum and diagonal band of Broca (MS-DBB) provide an important input to the hippocampus and are critically involved in learning and memory. Although cholinergic and GABAergic MS-DBB neurons are known to modulate hippocampal activity, the role of recently described glutamatergic MS-DBB neurons is unknown. Here, we examined the electrophysiological properties of glutamatergic MS-DBB neurons and tested whether they provide a functional synaptic input to the hippocampus. To visualize the glutamatergic neurons, we used MS-DBB slices from transgenic mice in which the green fluorescent protein is expressed specifically by vesicular glutamate transporter 2-positive neurons and characterized their properties using whole-cell patch-clamp technique. For assessing the function of the glutamatergic projection, we used an in vitro septohippocampal preparation, electrically stimulated the fornix or chemically activated the MS-DBB using NMDA microinfusions and recorded postsynaptic responses in CA3 pyramidal cells. We found that glutamatergic MS-DBB neurons as a population display a highly heterogeneous set of firing patterns including fast-, cluster-, burst-, and slow-firing. Remarkably, a significant proportion exhibited fast-firing properties, prominent I(h), and rhythmic spontaneous firing at theta frequencies similar to those found in GABAergic MS-DBB neurons. Activation of the MS-DBB led to fast, AMPA receptor-mediated glutamatergic responses in CA3 pyramidal cells. These results describe for the first time the electrophysiological signatures of glutamatergic MS-DBB neurons, their rhythmic firing properties, and their capacity to drive hippocampal principal neurons. Our findings suggest that the glutamatergic septohippocampal pathway may play an important role in hippocampal theta oscillations and relevant cognitive functions.

  3. Transient Receptor Potential Vanilloid 4-Induced Modulation of Voltage-Gated Sodium Channels in Hippocampal Neurons.

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    Hong, Zhiwen; Jie, Pinghui; Tian, Yujing; Chen, Tingting; Chen, Lei; Chen, Ling

    2016-01-01

    Transient receptor potential vanilloid 4 (TRPV4) is reported to control the resting membrane potential and increase excitability in many types of cells. Voltage-gated sodium channels (VGSCs) play an important role in initiating action potentials in neurons. However, whether VGSCs can be modulated by the activation of TRPV4 in hippocampal pyramidal neurons remains unknown. In this study, we tested the effect of TRPV4 agonists (GSK1016790A and 4α-PDD) on voltage-gated sodium current (I Na) in hippocampal CA1 pyramidal neurons and the protein levels of α/β-subunit of VGSCs in the hippocampus of mice subjected to intracerebroventricular (icv.) injection of GSK1016790A (GSK-injected mice). Herein, we report that I Na was inhibited by acute application of GSK1016790A or 4α-PDD. In the presence of TRPV4 agonists, the voltage-dependent inactivation curve shifted to the hyperpolarization, whereas the voltage-dependent activation curve remained unchanged. The TRPV4 agonist-induced inhibition of I Na was blocked by the TRPV4 antagonist or tetrodotoxin. Moreover, blocking protein kinase A (PKA) markedly attenuated the GSK1016790A-induced inhibition of I Na, whereas antagonism of protein kinase C or p38 mitogen-activated protein kinase did not change GSK1016790A action. Finally, the protein levels of Nav1.1, Nav1.2, and Nav1.6 in the hippocampus increased in GSK-injected mice, whereas those of Nav1.3 and Navβ1 remained nearly unchanged. We conclude that I Na is inhibited by the acute activation of TRPV4 through PKA signaling pathway in hippocampal pyramidal neurons, but protein expression of α-subunit of VGSCs is increased by sustained TRPV4 activation, which may compensate for the acute inhibition of I Na and provide a possibility for hyper-excitability upon sustained TRPV4 activation.

  4. Genetic deletion of melanin-concentrating hormone neurons impairs hippocampal short-term synaptic plasticity and hippocampal-dependent forms of short-term memory.

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    Le Barillier, Léa; Léger, Lucienne; Luppi, Pierre-Hervé; Fort, Patrice; Malleret, Gaël; Salin, Paul-Antoine

    2015-11-01

    The cognitive role of melanin-concentrating hormone (MCH) neurons, a neuronal population located in the mammalian postero-lateral hypothalamus sending projections to all cortical areas, remains poorly understood. Mainly activated during paradoxical sleep (PS), MCH neurons have been implicated in sleep regulation. The genetic deletion of the only known MCH receptor in rodent leads to an impairment of hippocampal dependent forms of memory and to an alteration of hippocampal long-term synaptic plasticity. By using MCH/ataxin3 mice, a genetic model characterized by a selective deletion of MCH neurons in the adult, we investigated the role of MCH neurons in hippocampal synaptic plasticity and hippocampal-dependent forms of memory. MCH/ataxin3 mice exhibited a deficit in the early part of both long-term potentiation and depression in the CA1 area of the hippocampus. Post-tetanic potentiation (PTP) was diminished while synaptic depression induced by repetitive stimulation was enhanced suggesting an alteration of pre-synaptic forms of short-term plasticity in these mice. Behaviorally, MCH/ataxin3 mice spent more time and showed a higher level of hesitation as compared to their controls in performing a short-term memory T-maze task, displayed retardation in acquiring a reference memory task in a Morris water maze, and showed a habituation deficit in an open field task. Deletion of MCH neurons could thus alter spatial short-term memory by impairing short-term plasticity in the hippocampus. Altogether, these findings could provide a cellular mechanism by which PS may facilitate memory encoding. Via MCH neuron activation, PS could prepare the day's learning by increasing and modulating short-term synaptic plasticity in the hippocampus. © 2015 Wiley Periodicals, Inc.

  5. Coexistence of Multiple Types of Synaptic Plasticity in Individual Hippocampal CA1 Pyramidal Neurons

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    Edelmann, Elke; Cepeda-Prado, Efrain; Leßmann, Volkmar

    2017-01-01

    Understanding learning and memory mechanisms is an important goal in neuroscience. To gain insights into the underlying cellular mechanisms for memory formation, synaptic plasticity processes are studied with various techniques in different brain regions. A valid model to scrutinize different ways to enhance or decrease synaptic transmission is recording of long-term potentiation (LTP) or long-term depression (LTD). At the single cell level, spike timing-dependent plasticity (STDP) protocols have emerged as a powerful tool to investigate synaptic plasticity with stimulation paradigms that also likely occur during memory formation in vivo. Such kind of plasticity can be induced by different STDP paradigms with multiple repeat numbers and stimulation patterns. They subsequently recruit or activate different molecular pathways and neuromodulators for induction and expression of STDP. Dopamine (DA) and brain-derived neurotrophic factor (BDNF) have been recently shown to be important modulators for hippocampal STDP at Schaffer collateral (SC)-CA1 synapses and are activated exclusively by distinguishable STDP paradigms. Distinct types of parallel synaptic plasticity in a given neuron depend on specific subcellular molecular prerequisites. Since the basal and apical dendrites of CA1 pyramidal neurons are known to be heterogeneous, and distance-dependent dendritic gradients for specific receptors and ion channels are described, the dendrites might provide domain specific locations for multiple types of synaptic plasticity in the same neuron. In addition to the distinct signaling and expression mechanisms of various types of LTP and LTD, activation of these different types of plasticity might depend on background brain activity states. In this article, we will discuss some ideas why multiple forms of synaptic plasticity can simultaneously and independently coexist and can contribute so effectively to increasing the efficacy of memory storage and processing capacity of the

  6. Spontaneous activity and rhythm assimilation reactions in baby rabbit hippocampal neurons during learning: age-related characteristics.

    Science.gov (United States)

    Kopytova, F V

    2006-03-01

    The neural mechanisms of the age-related characteristics of memory formation were studied in experiments based on a model providing an analog of a conditioned reflex to time: trace assimilation of the rhythm with which neurons in hippocampal field CA1 were stimulated, in rabbits aged 1-4 weeks and 5-6 months. Stages of changes in neuron spike activity characteristic for developing animals were described. In animals studied one week after birth, there was a predominance of silent cells and cells with low spontaneous activity. At 2-3 weeks of life, the level of spontaneous neuron activity increased, reaching adult levels by 25-30 days. The dynamics of the ontogenetic development of learning ability showed a number of stages: from virtually complete inability to form and assimilate traces of the rhythm (at age 6-7 days) to the stage of good formation and rapid forgetting (8-14 days), and, finally, the development of complete memory (25-30 days). The synchronous development of plastic rearrangements and the level of spontaneous neuron activity provided evidence of the direct involvement of the mechanisms underlying the formation of spontaneous spike activity in the organization of neural processes supporting adaptive reactions in the developing animal.

  7. Passive and synaptic properties of hippocampal neurons grown in microcultures and in mass cultures.

    Science.gov (United States)

    Mennerick, S; Que, J; Benz, A; Zorumski, C F

    1995-01-01

    1. We used whole cell recordings to compare passive membrane properties and synaptic properties of postnatal rat hippocampal neurons grown for 7-15 days in either conventional mass cultures or on physically restricted microisland cultures. Despite matching microisland and mass culture cell across several variables, there were significant differences between neurons in the two groups regarding passive membrane characteristics and synaptic properties. 2. Microisland neurons displayed significantly faster charging of the membrane capacitance than mass culture counterparts matched with microisland neurons for age, somal diameter, and transmitter phenotype. When we used a two-compartment equivalent circuit model to quantify this result, microisland neurons displayed approximately half the distal capacitance of mass culture neurons. These data suggest that microisland neurons elaborate less extensive neuritic arborizations than mass culture neurons. 3. Evoked synaptic responses were enhanced on microislands compared with mass cultures. Excitatory and inhibitory autaptic currents were more frequent and displayed larger amplitudes on single-neuron microislands than in matched mass culture neurons. 4. In recordings from pairs of neurons in the two environments, we observed a significantly higher probability of obtaining a monosynaptic response on two-neuron microislands than in matched mass culture pairs (85% vs. 42%). Evoked excitatory postsynaptic currents were also significantly larger in the microisland environment, with evoked excitatory synaptic currents from two-neuron microislands exhibiting a mean amplitude 20-fold larger than mass culture monosynaptic responses. 5. The differences in evoked synaptic responses were not reflected in differences in the amplitude or frequency of spontaneous miniature excitatory postsynaptic currents (mEPSCs). Analysis of mEPSC rise times, decay times, and peak amplitudes within individual cells suggests that electrotonic filtering is

  8. The ever-changing morphology of hippocampal granule neurons in physiology and pathology.

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    María eLlorens-Martín

    2016-01-01

    Full Text Available Newborn neurons are continuously added to the hippocampal dentate gyrus throughout adulthood. In this review, we analyze the maturational stages that newborn granule neurons go through, with a focus on their unique morphological features during each stage under both physiological and pathological circumstances. In addition, the influence of deleterious (such as schizophrenia, stress, Alzheimer’s disease, seizures, stroke, inflammation, dietary deficiencies, or the consumption of drugs of abuse or toxic substances and neuroprotective (physical exercise and environmental enrichment stimuli on the maturation of these cells will be examined. Finally, the regulation of this process by proteins involved in neurodegenerative and neurological disorders (such as Glycogen synthase kinase 3β, Disrupted in Schizophrenia 1 (DISC-1, Glucocorticoid receptor, pro-inflammatory mediators, Presenilin-1, Amyloid precursor protein, Cyclin-dependent kinase 5 (CDK5, among others, will be evaluated. Given the recently acquired relevance of the dendritic branch as a functional synaptic unit required for memory storage, a full understanding of the morphological alterations observed in newborn neurons may have important consequences for the prevention and treatment of the cognitive and affective alterations that evolve in conjunction with impaired adult hippocampal neurogenesis.

  9. Aging Triggers a Repressive Chromatin State at Bdnf Promoters in Hippocampal Neurons

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    Ernest Palomer

    2016-09-01

    Full Text Available Cognitive capacities decline with age, an event accompanied by the altered transcription of synaptic plasticity genes. Here, we show that the transcriptional induction of Bdnf by a mnemonic stimulus is impaired in aged hippocampal neurons. Mechanistically, this defect is due to reduced NMDA receptor (NMDAR-mediated activation of CaMKII. Decreased NMDAR signaling prevents changes associated with activation at specific Bdnf promoters, including displacement of histone deacetylase 4, recruitment of the histone acetyltransferase CBP, increased H3K27 acetylation, and reduced H3K27 trimethylation. The decrease in NMDA-CaMKII signaling arises from constitutive reduction of synaptic cholesterol that occurs with normal aging. Increasing the levels of neuronal cholesterol in aged neurons in vitro, ex vivo, and in vivo restored NMDA-induced Bdnf expression and chromatin remodeling. Furthermore, pharmacological prevention of age-associated cholesterol reduction rescued signaling and cognitive deficits of aged mice. Thus, reducing hippocampal cholesterol loss may represent a therapeutic approach to reverse cognitive decline during aging.

  10. Calcium signals can freely cross the nuclear envelope in hippocampal neurons: somatic calcium increases generate nuclear calcium transients

    OpenAIRE

    Eder, Anja; Bading, Hilmar

    2007-01-01

    Abstract Background In hippocampal neurons, nuclear calcium signaling is important for learning- and neuronal survival-associated gene expression. However, it is unknown whether calcium signals generated by neuronal activity at the cell membrane and propagated to the soma can unrestrictedly cross the nuclear envelope to invade the nucleus. The nuclear envelope, which allows ion transit via the nuclear pore complex, may represent a barrier for calcium and has been suggested to insulate the nuc...

  11. Astaxanthin Protects Primary Hippocampal Neurons against Noxious Effects of Aβ-Oligomers

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    Pedro Lobos

    2016-01-01

    Full Text Available Increased reactive oxygen species (ROS generation and the ensuing oxidative stress contribute to Alzheimer’s disease pathology. We reported previously that amyloid-β peptide oligomers (AβOs produce aberrant Ca2+ signals at sublethal concentrations and decrease the expression of type-2 ryanodine receptors (RyR2, which are crucial for hippocampal synaptic plasticity and memory. Here, we investigated whether the antioxidant agent astaxanthin (ATX protects neurons from AβOs-induced excessive mitochondrial ROS generation, NFATc4 activation, and RyR2 mRNA downregulation. To determine mitochondrial H2O2 production or NFATc4 nuclear translocation, neurons were transfected with plasmids coding for HyperMito or NFATc4-eGFP, respectively. Primary hippocampal cultures were incubated with 0.1 μM ATX for 1.5 h prior to AβOs addition (500 nM. We found that incubation with ATX (≤10 μM for ≤24 h was nontoxic to neurons, evaluated by the live/dead assay. Preincubation with 0.1 μM ATX also prevented the neuronal mitochondrial H2O2 generation induced within minutes of AβOs addition. Longer exposures to AβOs (6 h promoted NFATc4-eGFP nuclear translocation and decreased RyR2 mRNA levels, evaluated by detection of the eGFP-tagged fluorescent plasmid and qPCR, respectively. Preincubation with 0.1 μM ATX prevented both effects. These results indicate that ATX protects neurons from the noxious effects of AβOs on mitochondrial ROS production, NFATc4 activation, and RyR2 gene expression downregulation.

  12. Oxidative Stress Mediated Hippocampal Neuron Apoptosis Participated in Carbon Disulfide-Induced Rats Cognitive Dysfunction.

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    Wang, Shuo; Irving, Gleniece; Jiang, Lulu; Wang, Hui; Li, Ming; Wang, Xujing; Han, Wenting; Xu, Yongpeng; Yang, Yilin; Zeng, Tao; Song, Fuyong; Zhao, Xiulan; Xie, Keqin

    2017-02-01

    Occupational exposure to carbon disulfide (CS2) exhibits central nervous systems toxicity. But the mechanism is unclear. The present study was designed to investigate the relationship between the CNS damage and cognitive dysfunction caused by CS2, and eventually reveal the possible oxidative-related mechanism of hippocampus pathological changes in CS2 exposed rats. Male Wistar rats were administrated with CS2 at dosage of 200, 400 and 600 mg/kg for consecutive 20 days, respectively. Cognitive performances were evaluated by Morris water maze tests. Thionin and immunohistochemical analysis were used to investigate the hippocampal neuron damage, and the expression of apoptosis related proteins (cleaved-caspase 3, Bax and Bcl-2) were detected to explore the possible mechanisms of neuronal loss. Oxidative stress parameters were checked by commercial assay kits. Rats exposed to CS2 displayed cognitive dysfunction manifested as decreased spatial learning ability and memory lesion. Pathological changes and significant neuron loss were observed in hippocampus, especially in CA1 and CA3 sub-regions. Mitochondria-dependent apoptosis pathway was implicated in the CS2-induced neuronal loss which was demonstrated by the up-regulation of cleaved-caspase 3 and Bax accompanied with down-regulation of Bcl-2. Furthermore, extensive oxidative stress induced by CS2 was also revealed by the measurement of ROS, RNS, MDA, GSH&GSSG and antioxidant enzymes (CAT, T-SOD, and GSH-Px). Our study suggested that oxidative stress mediated hippocampal neuron apoptosis might play an important role in CS2 induced CNS damage and cognitive dysfunction.

  13. Roles of PTEN-induced putative kinase 1 and dynamin-related protein 1 in transient global ischemia-induced hippocampal neuronal injury

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Shang-Der, E-mail: chensd@adm.cgmh.org.tw [Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Taiwan (China); Center for Translational Research in Biomedical Sciences, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Taiwan (China); Lin, Tsu-Kung [Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Taiwan (China); Yang, Ding-I. [Institute of Brain Science and Brain Research Center, National Yang-Ming University, Taipei, Taiwan (China); Lee, Su-Ying [Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Taiwan (China); Shaw, Fu-Zen [Department of Psychology, National Cheng Kung University, Tainan, Taiwan (China); Liou, Chia-Wei [Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Taiwan (China); Chuang, Yao-Chung, E-mail: ycchuang@adm.cgmh.org.tw [Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Taiwan (China); Center for Translational Research in Biomedical Sciences, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Taiwan (China)

    2015-05-01

    Recent studies showed that increased mitochondrial fission is an early event of cell death during cerebral ischemia and dynamin-related protein 1 (Drp1) plays an important role in mitochondrial fission, which may be regulated by PTEN-induced putative kinase 1 (PINK1), a mitochondrial serine/threonine-protein kinase thought to protect cells from stress-induced mitochondrial dysfunction and regulate mitochondrial fission. However, the roles of PINK1 and Drp1 in hippocampal injury caused by transient global ischemia (TGI) remain unknown. We therefore tested the hypothesis that TGI may induce PINK1 causing downregulation of Drp1 phosphorylation to enhance hippocampal neuronal survival, thus functioning as an endogenous neuroprotective mechanism. We found progressively increased PINK1 expression in the hippocampal CA1 subfield1-48 h following TGI, reaching the maximal level at 4 h. Despite lack of changes in the expression level of total Drp1 and phosphor-Drp1 at Ser637, TGI induced a time-dependent increase of Drp1 phosphorlation at Ser616 that peaked after 24 h. Notably, PINK1-siRNA increased p-Drp1(Ser616) protein level in hippocampal CA1 subfield 24 h after TGI. The PINK1 siRNA also aggravated the TGI-induced oxidative DNA damage with an increased 8-hydroxy-deoxyguanosine (8-OHdG) content in hippocampal CA1 subfield. Furthermore, PINK1 siRNA also augmented TGI-induced apoptosis as evidenced by the increased numbers of TUNEL-positive staining and enhanced DNA fragmentation. These findings indicated that PINK1 is an endogenous protective mediator vital for neuronal survival under ischemic insult through regulating Drp1 phosphorylation at Ser616. - Highlights: • Transient global ischemia increases expression of PINK1 and p-Drp1 at Ser616 in hippocampal CA1 subfield. • PINK1-siRNA decreases PINK1 expression but increases p-Drp1 at Ser616 in hippocampal CA1 subfield. • PINK1-siRNA augments oxidative stress and neuronal damage in hippocampal CA1 subfield.

  14. Modulators of cytoskeletal reorganization in CA1 hippocampal neurons show increased expression in patients at mid-stage Alzheimer's disease.

    Directory of Open Access Journals (Sweden)

    Patricia F Kao

    2010-10-01

    Full Text Available During the progression of Alzheimer's disease (AD, hippocampal neurons undergo cytoskeletal reorganization, resulting in degenerative as well as regenerative changes. As neurofibrillary tangles form and dystrophic neurites appear, sprouting neuronal processes with growth cones emerge. Actin and tubulin are indispensable for normal neurite development and regenerative responses to injury and neurodegenerative stimuli. We have previously shown that actin capping protein beta2 subunit, Capzb2, binds tubulin and, in the presence of tau, affects microtubule polymerization necessary for neurite outgrowth and normal growth cone morphology. Accordingly, Capzb2 silencing in hippocampal neurons resulted in short, dystrophic neurites, seen in neurodegenerative diseases including AD. Here we demonstrate the statistically significant increase in the Capzb2 expression in the postmortem hippocampi in persons at mid-stage, Braak and Braak stage (BB III-IV, non-familial AD in comparison to controls. The dynamics of Capzb2 expression in progressive AD stages cannot be attributed to reactive astrocytosis. Moreover, the increased expression of Capzb2 mRNA in CA1 pyramidal neurons in AD BB III-IV is accompanied by an increased mRNA expression of brain derived neurotrophic factor (BDNF receptor tyrosine kinase B (TrkB, mediator of synaptic plasticity in hippocampal neurons. Thus, the up-regulation of Capzb2 and TrkB may reflect cytoskeletal reorganization and/or regenerative response occurring in hippocampal CA1 neurons at a specific stage of AD progression.

  15. Apamin induces plastic changes in hippocampal neurons in senile Sprague-Dawley rats.

    Science.gov (United States)

    Romero-Curiel, Alejandra; López-Carpinteyro, Diana; Gamboa, Citlalli; De la Cruz, Fidel; Zamudio, Sergio; Flores, Gonzalo

    2011-10-01

    Apamin is a neurotoxin extracted from honey bee venom and is a selective blocker of small-conductance Ca²⁺-activated K⁺ channels (SK). Several behavioral and electrophysiological studies indicate that SK-blockade by apamin may enhance neuron excitability, synaptic plasticity, and long-term potentiation in the CA1 hippocampal region, and, for that reason, apamin has been proposed as a therapeutic agent in Alzheimer's disease treatment. However, the dendritic morphological mechanisms implied in such enhancement are unknown. In the present work, Golgi-Cox stain protocol and Sholl analysis were used to study the effect of apamin on the dendritic morphology of pyramidal neurons from hippocampus and the prefrontal cortex as well as on the medium spiny neurons from the nucleus accumbens and granule cells from the dentate gyrus (DG) of the hippocampus. We found that only granule cells from the DG and pyramidal neurons from dorsal and ventral hippocampus were altered in senile rats injected with apamin. Our research suggests that apamin may increase the dendritic morphology in the hippocampus, which could be related to the neuronal excitability and synaptic plasticity enhancement induced by apamin. Copyright © 2011 Wiley-Liss, Inc.

  16. Ionic mechanisms of endogenous bursting in CA3 hippocampal pyramidal neurons: a model study.

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    Jun Xu

    2008-04-01

    Full Text Available A critical property of some neurons is burst firing, which in the hippocampus plays a primary role in reliable transmission of electrical signals. However, bursting may also contribute to synchronization of electrical activity in networks of neurons, a hallmark of epilepsy. Understanding the ionic mechanisms of bursting in a single neuron, and how mutations associated with epilepsy modify these mechanisms, is an important building block for understanding the emergent network behaviors. We present a single-compartment model of a CA3 hippocampal pyramidal neuron based on recent experimental data. We then use the model to determine the roles of primary depolarizing currents in burst generation. The single compartment model incorporates accurate representations of sodium (Na(+ channels (Na(V1.1 and T-type calcium (Ca(2+ channel subtypes (Ca(V3.1, Ca(V3.2, and Ca(V3.3. Our simulations predict the importance of Na(+ and T-type Ca(2+ channels in hippocampal pyramidal cell bursting and reveal the distinct contribution of each subtype to burst morphology. We also performed fast-slow analysis in a reduced comparable model, which shows that our model burst is generated as a result of the interaction of two slow variables, the T-type Ca(2+ channel activation gate and the Ca(2+-dependent potassium (K(+ channel activation gate. The model reproduces a range of experimentally observed phenomena including afterdepolarizing potentials, spike widening at the end of the burst, and rebound. Finally, we use the model to simulate the effects of two epilepsy-linked mutations: R1648H in Na(V1.1 and C456S in Ca(V3.2, both of which result in increased cellular excitability.

  17. The active zone protein family ELKS supports Ca2+ influx at nerve terminals of inhibitory hippocampal neurons.

    Science.gov (United States)

    Liu, Changliang; Bickford, Lydia S; Held, Richard G; Nyitrai, Hajnalka; Südhof, Thomas C; Kaeser, Pascal S

    2014-09-10

    In a presynaptic nerve terminal, synaptic vesicle exocytosis is restricted to specialized sites called active zones. At these sites, neurotransmitter release is determined by the number of releasable vesicles and their probability of release. Proteins at the active zone set these parameters by controlling the presynaptic Ca(2+) signal, and through docking and priming of synaptic vesicles. Vertebrate ELKS proteins are enriched at presynaptic active zones, but their functions are not well understood. ELKS proteins are produced by two genes in vertebrates, and each gene contributes ∼50% to total brain ELKS. We generated knock-out mice for ELKS1 and found that its constitutive removal causes lethality. To bypass lethality, and to circumvent redundancy between ELKS1 and ELKS2 in synaptic transmission, we used a conditional genetic approach to remove both genes in cultured hippocampal neurons after synapses are established. Simultaneous removal of ELKS1 and ELKS2 resulted in a 50% decrease of neurotransmitter release at inhibitory synapses, paralleled by a reduction in release probability. Removal of ELKS did not affect synapse numbers or their electron microscopic appearance. Using Ca(2+) imaging, we found that loss of ELKS caused a 30% reduction in single action potential-triggered Ca(2+) influx in inhibitory nerve terminals, consistent with the deficits in synaptic transmission and release probability. Unlike deletion of the active zone proteins RIM, RIM-BP, or bruchpilot, ELKS removal did not lead to a measurable reduction in presynaptic Ca(2+) channel levels. Our results reveal that ELKS is required for normal Ca(2+) influx at nerve terminals of inhibitory hippocampal neurons. Copyright © 2014 the authors 0270-6474/14/3412289-15$15.00/0.

  18. TrkB gene transfer does not alter hippocampal neuronal loss and cognitive deficits following traumatic brain injury in mice.

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    Conte, Valeria; Raghupathi, Ramesh; Watson, Deborah J; Fujimoto, Scott; Royo, Nicolas C; Marklund, Niklas; Stocchetti, Nino; McIntosh, Tracy K

    2008-01-01

    The ability of brain-derived neurotrophic factor (BDNF) to attenuate secondary damage and influence behavioral outcome after experimental traumatic brain injury (TBI) remains controversial. Because TBI can result in decreased expression of the trkB receptor, thereby preventing BDNF from exerting potential neuroprotective effects, the contribution of both BDNF and its receptor trkB to hippocampal neuronal loss and cognitive dysfunction were evaluated. Full-length trkB was overexpressed in the left hippocampus of adult C57Bl/6 mice using recombinant adeno-associated virus serotype 2/5 (rAAV 2/5). EGFP (enhanced green fluorescent protein) expression was present at two weeks after AAV-EGFP injection and remained sustained up to four weeks after the injection. At 2 weeks following gene transduction, mice were subjected to parasagittal controlled cortical impact (CCI) brain injury, followed by either BDNF or PBS infusion into the hippocampus. No differences were observed in learning ability at two weeks post-injury or in motor function from 48 hours to two weeks among treatment groups. The number of surviving pyramidal neurons in the CA2-CA3 region of the hippocampus was also not different among treatment groups. These data suggest that neither overexpression of trkB, BNDF infusion or their combination affects neuronal survival or behavioral outcome following experimental TBI in mice.

  19. Amyloid-Beta Induced Changes in Vesicular Transport of BDNF in Hippocampal Neurons

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    Bianca Seifert

    2016-01-01

    Full Text Available The neurotrophin brain derived neurotrophic factor (BDNF is an important growth factor in the CNS. Deficits in transport of this secretory protein could underlie neurodegenerative diseases. Investigation of disease-related changes in BDNF transport might provide insights into the cellular mechanism underlying, for example, Alzheimer’s disease (AD. To analyze the role of BDNF transport in AD, live cell imaging of fluorescently labeled BDNF was performed in hippocampal neurons of different AD model systems. BDNF and APP colocalized with low incidence in vesicular structures. Anterograde as well as retrograde transport of BDNF vesicles was reduced and these effects were mediated by factors released from hippocampal neurons into the extracellular medium. Transport of BDNF was altered at a very early time point after onset of human APP expression or after acute amyloid-beta(1-42 treatment, while the activity-dependent release of BDNF remained unaffected. Taken together, extracellular cleavage products of APP induced rapid changes in anterograde and retrograde transport of BDNF-containing vesicles while release of BDNF was unaffected by transgenic expression of mutated APP. These early transport deficits might lead to permanently impaired brain functions in the adult brain.

  20. 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.

  1. Point application with Angong Niuhuang sticker protects hippocampal and cortical neurons in rats with cerebral ischemia

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    Dong-shu Zhang

    2015-01-01

    Full Text Available Angong Niuhuang pill, a Chinese materia medica preparation, can improve neurological functions after acute ischemic stroke. Because of its inconvenient application and toxic components (Cinnabaris and Realgar, we used transdermal enhancers to deliver Angong Niuhuang pill by modern technology, which expanded the safe dose range and clinical indications. In this study, Angong Niuhuang stickers administered at different point application doses (1.35, 2.7, and 5.4 g/kg were administered to the Dazhui (DU14, Qihai (RN6 and Mingmen (DU4 of rats with chronic cerebral ischemia, for 4 weeks. The Morris water maze was used to determine the learning and memory ability of rats. Hematoxylin-eosin staining and Nissl staining were used to observe neuronal damage of the cortex and hippocampal CA1 region in rats with chronic cerebral ischemia. The middle- and high-dose point application of Angong Niuhuang stickers attenuated neuronal damage in the cortex and hippocampal CA1 region, and improved the memory of rats with chronic cerebral ischemia with an efficacy similar to interventions by electroacupuncture at Dazhui (DU14, Qihai (RN6 and Mingmen (DU4. Our experimental findings indicate that point application with Angong Niuhuang stickers can improve cognitive function after chronic cerebral ischemia in rats and is neuroprotective with an equivalent efficacy to acupuncture.

  2. Point application with Angong Niuhuang sticker protects hippocampal and cortical neurons in rats with cerebral ischemia

    Science.gov (United States)

    Zhang, Dong-shu; Liu, Yuan-liang; Zhu, Dao-qi; Huang, Xiao-jing; Luo, Chao-hua

    2015-01-01

    Angong Niuhuang pill, a Chinese materia medica preparation, can improve neurological functions after acute ischemic stroke. Because of its inconvenient application and toxic components (Cinnabaris and Realgar), we used transdermal enhancers to deliver Angong Niuhuang pill by modern technology, which expanded the safe dose range and clinical indications. In this study, Angong Niuhuang stickers administered at different point application doses (1.35, 2.7, and 5.4 g/kg) were administered to the Dazhui (DU14), Qihai (RN6) and Mingmen (DU4) of rats with chronic cerebral ischemia, for 4 weeks. The Morris water maze was used to determine the learning and memory ability of rats. Hematoxylin-eosin staining and Nissl staining were used to observe neuronal damage of the cortex and hippocampal CA1 region in rats with chronic cerebral ischemia. The middle- and high-dose point application of Angong Niuhuang stickers attenuated neuronal damage in the cortex and hippocampal CA1 region, and improved the memory of rats with chronic cerebral ischemia with an efficacy similar to interventions by electroacupuncture at Dazhui (DU14), Qihai (RN6) and Mingmen (DU4). Our experimental findings indicate that point application with Angong Niuhuang stickers can improve cognitive function after chronic cerebral ischemia in rats and is neuroprotective with an equivalent efficacy to acupuncture. PMID:25883629

  3. The Gαo Activator Mastoparan-7 Promotes Dendritic Spine Formation in Hippocampal Neurons

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    Valerie T. Ramírez

    2016-01-01

    Full Text Available Mastoparan-7 (Mas-7, an analogue of the peptide mastoparan, which is derived from wasp venom, is a direct activator of Pertussis toxin- (PTX- sensitive G proteins. Mas-7 produces several biological effects in different cell types; however, little is known about how Mas-7 influences mature hippocampal neurons. We examined the specific role of Mas-7 in the development of dendritic spines, the sites of excitatory synaptic contact that are crucial for synaptic plasticity. We report here that exposure of hippocampal neurons to a low dose of Mas-7 increases dendritic spine density and spine head width in a time-dependent manner. Additionally, Mas-7 enhances postsynaptic density protein-95 (PSD-95 clustering in neurites and activates Gαo signaling, increasing the intracellular Ca2+ concentration. To define the role of signaling intermediates, we measured the levels of phosphorylated protein kinase C (PKC, c-Jun N-terminal kinase (JNK, and calcium-calmodulin dependent protein kinase IIα (CaMKIIα after Mas-7 treatment and determined that CaMKII activation is necessary for the Mas-7-dependent increase in dendritic spine density. Our results demonstrate a critical role for Gαo subunit signaling in the regulation of synapse formation.

  4. Allopregnanolone-induced rise in intracellular calcium in embryonic hippocampal neurons parallels their proliferative potential

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    Brinton Roberta

    2008-12-01

    Full Text Available Abstract Background Factors that regulate intracellular calcium concentration are known to play a critical role in brain function and neural development, including neural plasticity and neurogenesis. We previously demonstrated that the neurosteroid allopregnanolone (APα; 5α-pregnan-3α-ol-20-one promotes neural progenitor proliferation in vitro in cultures of rodent hippocampal and human cortical neural progenitors, and in vivo in triple transgenic Alzheimer's disease mice dentate gyrus. We also found that APα-induced proliferation of neural progenitors is abolished by a calcium channel blocker, nifedipine, indicating a calcium dependent mechanism for the proliferation. Methods In the present study, we investigated the effect of APα on the regulation of intracellular calcium concentration in E18 rat hippocampal neurons using ratiometric Fura2-AM imaging. Results Results indicate that APα rapidly increased intracellular calcium concentration in a dose-dependent and developmentally regulated manner, with an EC50 of 110 ± 15 nM and a maximal response occurring at three days in vitro. The stereoisomers 3β-hydroxy-5α-hydroxy-pregnan-20-one, and 3β-hydroxy-5β-hydroxy-pregnan-20-one, as well as progesterone, were without significant effect. APα-induced intracellular calcium concentration increase was not observed in calcium depleted medium and was blocked in the presence of the broad spectrum calcium channel blocker La3+, or the L-type calcium channel blocker nifedipine. Furthermore, the GABAA receptor blockers bicuculline and picrotoxin abolished APα-induced intracellular calcium concentration rise. Conclusion Collectively, these data indicate that APα promotes a rapid, dose-dependent, stereo-specific, and developmentally regulated increase of intracellular calcium concentration in rat embryonic hippocampal neurons via a mechanism that requires both the GABAA receptor and L-type calcium channel. These data suggest that AP

  5. Neuron and neuroblast numbers and cytogenesis in the dentate gyrus of aged APP(swe)/PS1(dE9) transgenic mice

    DEFF Research Database (Denmark)

    Olesen, Louise Orum; Sivasaravanaparan, Mithula; Severino, Maurizio

    2017-01-01

    the longitudinal changes in the number of doublecortin-expressing neuroblasts and number of granular neurons in the dentate gyrus of APPswe/PS1dE9 transgenic mice. Furthermore, we investigated the effect of long-term paroxetine treatment on the number of neuroblasts and granular neurons, hippocampal amyloidosis......, and spontaneous alternation behaviour, a measure of spatial working memory, in transgenic mice. We observed no difference in granular neurons between transgenic and wild type mice up till 18 months of age, and no differences with age in wild type mice. The number of neuroblasts and the performance...... in the spontaneous alternation task was reduced in aged transgenic mice. Paroxetine treatment from 9 to 18 months of age reduced hippocampal amyloidosis without affecting the number of neuroblasts or granular neurons. These findings suggest that the amyloidosis affects the differentiation of neuroblasts and spatial...

  6. In Vivo AAV1 Transduction With hRheb(S16H) Protects Hippocampal Neurons by BDNF Production

    Science.gov (United States)

    Jeon, Min-Tae; Nam, Jin Han; Shin, Won-Ho; Leem, Eunju; Jeong, Kyoung Hoon; Jung, Un Ju; Bae, Young-Seuk; Jin, Young-Ho; Kholodilov, Nikolai; Burke, Robert E; Lee, Seok-Geun; Jin, Byung Kwan; Kim, Sang Ryong

    2015-01-01

    Recent evidence has shown that Ras homolog enriched in brain (Rheb) is dysregulated in Alzheimer's disease (AD) brains. However, it is still unclear whether Rheb activation contributes to the survival and protection of hippocampal neurons in the adult brain. To assess the effects of active Rheb in hippocampal neurons in vivo, we transfected neurons in the cornu ammonis 1 (CA1) region in normal adult rats with an adeno-associated virus containing the constitutively active human Rheb (hRheb(S16H)) and evaluated the effects on thrombin-induced neurotoxicity. Transduction with hRheb(S16H) significantly induced neurotrophic effects in hippocampal neurons through activation of mammalian target of rapamycin complex 1 (mTORC1) without side effects such as long-term potentiation impairment and seizures from the alteration of cytoarchitecture, and the expression of hRheb(S16H) prevented thrombin-induced neurodegeneration in vivo, an effect that was diminished by treatment with specific neutralizing antibodies against brain-derived neurotrophic factor (BDNF). In addition, our results showed that the basal mTORC1 activity might be insufficient to mediate the level of BDNF expression, but hRheb(S16H)-activated mTORC1 stimulated BDNF production in hippocampal neurons. These results suggest that viral vector transduction with hRheb(S16H) may have therapeutic value in the treatment of neurodegenerative diseases such as AD. PMID:25502903

  7. In vivo AAV1 transduction with hRheb(S16H) protects hippocampal neurons by BDNF production.

    Science.gov (United States)

    Jeon, Min-Tae; Nam, Jin Han; Shin, Won-Ho; Leem, Eunju; Jeong, Kyoung Hoon; Jung, Un Ju; Bae, Young-Seuk; Jin, Young-Ho; Kholodilov, Nikolai; Burke, Robert E; Lee, Seok-Geun; Jin, Byung Kwan; Kim, Sang Ryong

    2015-03-01

    Recent evidence has shown that Ras homolog enriched in brain (Rheb) is dysregulated in Alzheimer's disease (AD) brains. However, it is still unclear whether Rheb activation contributes to the survival and protection of hippocampal neurons in the adult brain. To assess the effects of active Rheb in hippocampal neurons in vivo, we transfected neurons in the cornu ammonis 1 (CA1) region in normal adult rats with an adeno-associated virus containing the constitutively active human Rheb (hRheb(S16H)) and evaluated the effects on thrombin-induced neurotoxicity. Transduction with hRheb(S16H) significantly induced neurotrophic effects in hippocampal neurons through activation of mammalian target of rapamycin complex 1 (mTORC1) without side effects such as long-term potentiation impairment and seizures from the alteration of cytoarchitecture, and the expression of hRheb(S16H) prevented thrombin-induced neurodegeneration in vivo, an effect that was diminished by treatment with specific neutralizing antibodies against brain-derived neurotrophic factor (BDNF). In addition, our results showed that the basal mTORC1 activity might be insufficient to mediate the level of BDNF expression, but hRheb(S16H)-activated mTORC1 stimulated BDNF production in hippocampal neurons. These results suggest that viral vector transduction with hRheb(S16H) may have therapeutic value in the treatment of neurodegenerative diseases such as AD.

  8. Survival of hippocampal and cortical neurons in a mixture of MEM+ and B27-supplemented neurobasal medium.

    Science.gov (United States)

    Xie, C; Markesbery, W R; Lovell, M A

    2000-03-01

    Serum-free B-27 supplemented neurobasal (NB) and a 10% fetal bovine serum-supplemented Eagle's minimum essential medium (MEM+) are used to culture rat embryonic hippocampal neurons for different purposes. Although NB medium leads to enhanced cell survival, it contains biological antioxidants and is not suitable for the study of free radical damage and oxidation in cultured neurons. MEM+ without additional antioxidants has been used widely in the study of free radical damage and oxidation, although it does not support optimum neuronal survival in culture. Serum in MEM+ leads to enhanced cell survival but also promotes glial cell proliferation. In this study, we used a new combination medium (NM-2) that consists of both NB and MEM+ for growing primary hippocampal and cortical neuronal cultures. NM-2 enhanced neuronal survival 78.9% for dissociated neurons at a density of 50 cells/mm(2) and 83.1% for 100 cells/mm(2), while decreasing glial cell proliferation to 2-3% and completely inhibiting oligodendrocytes. The NM-2 minimized the effectiveness of antioxidants in the medium to the neurotoxin 4-hydroxynonenal. It also decreased neuronal clumping and provided a more even distribution of neurons. Neurons survived for 4 weeks in NM-2 without changing the original medium. NM-2 provides a good environment for studies of free radical damage and oxidation of neurons. The combination incorporates the best of both NB and MEM+ that results in high neuron survival rate, low glial cell proliferation, reduced antioxidant level, and provides relatively pure cultures of hippocampal and cortical neurons.

  9. Complex effects of aqueous extract of Melampyrum pratense and of its flavonoids on activity of primary cultured hippocampal neurons.

    Science.gov (United States)

    Korkotian, Eduard; Botalova, Alena; Odegova, Tatiana; Galishevskaya, Elena; Skryabina, Eugenia; Segal, Menahem

    2015-04-02

    The aqueous extract of the plant Malmpyrum pratense (Mp), is widely used in traditional medicine as a sedative, yet the biological basis of its action is not known. The effects of Mp on network activity and intrinsic and synaptic properties were studied in cultured hippocampal neurons in an attempt to analyze its mode of action. Dissociated cultures of rat hippocampal neurons were used. Spontaneous network activity was assessed by variations in intracellular [Ca(2+)] concentrations, reflecting action potential discharges. Individual neuronal synaptic activity was measured by patch clamp recordings from similar neurons. The effect of exposure to different concentrations of Mp and some of its main ingredients was measured. Mp produced complex, dose dependent, reversible effects on network activity, increasing it with low concentrations, and decreasing it at high concentrations. Individual flavonoids contained in Mp mimicked the effects of the extract, both for the facilitating and suppressing effects of the extract. Electrophysiologically, Mp caused a reduction in spontaneous activity, but did not affect membrane properties of individual patch clamped neurons, nor did it affect mEPSCs recorded from these neurons. However, a transient increase in reactivity to pulse application of GABA was evident. These results suggest that a main sedative effect of Mp is on GABAergic neurotransmission in cultured hippocampal neurons. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  10. Learning causes reorganization of neuronal firing patterns to represent related experiences within a hippocampal schema.

    Science.gov (United States)

    McKenzie, Sam; Robinson, Nick T M; Herrera, Lauren; Churchill, Jordana C; Eichenbaum, Howard

    2013-06-19

    According to schema theory as proposed by Piaget and Bartlett, learning involves the assimilation of new memories into networks of preexisting knowledge, as well as alteration of the original networks to accommodate the new information. Recent evidence has shown that rats form a schema of goal locations and that the hippocampus plays an essential role in adding new memories to the spatial schema. Here we examined the nature of hippocampal contributions to schema updating by monitoring firing patterns of multiple CA1 neurons as rats learned new goal locations in an environment in which there already were multiple goals. Before new learning, many neurons that fired on arrival at one goal location also fired at other goals, whereas ensemble activity patterns also distinguished different goal events, thus constituting a neural representation that linked distinct goals within a spatial schema. During new learning, some neurons began to fire as animals approached the new goals. These were primarily the same neurons that fired at original goals, the activity patterns at new goals were similar to those associated with the original goals, and new learning also produced changes in the preexisting goal-related firing patterns. After learning, activity patterns associated with the new and original goals gradually diverged, such that initial generalization was followed by a prolonged period in which new memories became distinguished within the ensemble representation. These findings support the view that consolidation involves assimilation of new memories into preexisting neural networks that accommodate relationships among new and existing memories.

  11. Tissue-based metabolic labeling of polysialic acids in living primary hippocampal neurons.

    Science.gov (United States)

    Kang, Kyungtae; Joo, Sunghoon; Choi, Ji Yu; Geum, Sujeong; Hong, Seok-Pyo; Lee, Seung-Yeul; Kim, Yong Ho; Kim, Seong-Min; Yoon, Myung-Han; Nam, Yoonkey; Lee, Kyung-Bok; Lee, Hee-Yoon; Choi, Insung S

    2015-01-20

    The posttranslational modification of neural cell-adhesion molecule (NCAM) with polysialic acid (PSA) and the spatiotemporal distribution of PSA-NCAM play an important role in the neuronal development. In this work, we developed a tissue-based strategy for metabolically incorporating an unnatural monosaccharide, peracetylated N-azidoacetyl-D-mannosamine, in the sialic acid biochemical pathway to present N-azidoacetyl sialic acid to PSA-NCAM. Although significant neurotoxicity was observed in the conventional metabolic labeling that used the dissociated neuron cells, neurotoxicity disappeared in this modified strategy, allowing for investigation of the temporal and spatial distributions of PSA in the primary hippocampal neurons. PSA-NCAM was synthesized and recycled continuously during neuronal development, and the two-color labeling showed that newly synthesized PSA-NCAMs were transported and inserted mainly to the growing neurites and not significantly to the cell body. This report suggests a reliable and cytocompatible method for in vitro analysis of glycans complementary to the conventional cell-based metabolic labeling for chemical glycobiology.

  12. Visualizing Metal Content and Intracellular Distribution in Primary Hippocampal Neurons with Synchrotron X-Ray Fluorescence.

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    Robert A Colvin

    Full Text Available Increasing evidence suggests that metal dyshomeostasis plays an important role in human neurodegenerative diseases. Although distinctive metal distributions are described for mature hippocampus and cortex, much less is known about metal levels and intracellular distribution in individual hippocampal neuronal somata. To solve this problem, we conducted quantitative metal analyses utilizing synchrotron radiation X-Ray fluorescence on frozen hydrated primary cultured neurons derived from rat embryonic cortex (CTX and two regions of the hippocampus: dentate gyrus (DG and CA1. Comparing average metal contents showed that the most abundant metals were calcium, iron, and zinc, whereas metals such as copper and manganese were less than 10% of zinc. Average metal contents were generally similar when compared across neurons cultured from CTX, DG, and CA1, except for manganese that was larger in CA1. However, each metal showed a characteristic spatial distribution in individual neuronal somata. Zinc was uniformly distributed throughout the cytosol, with no evidence for the existence of previously identified zinc-enriched organelles, zincosomes. Calcium showed a peri-nuclear distribution consistent with accumulation in endoplasmic reticulum and/or mitochondria. Iron showed 2-3 distinct highly concentrated puncta only in peri-nuclear locations. Notwithstanding the small sample size, these analyses demonstrate that primary cultured neurons show characteristic metal signatures. The iron puncta probably represent iron-accumulating organelles, siderosomes. Thus, the metal distributions observed in mature brain structures are likely the result of both intrinsic neuronal factors that control cellular metal content and extrinsic factors related to the synaptic organization, function, and contacts formed and maintained in each region.

  13. 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

  14. Maternal Exercise during Pregnancy Increases BDNF Levels and Cell Numbers in the Hippocampal Formation but Not in the Cerebral Cortex of Adult Rat Offspring.

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    Sérgio Gomes da Silva

    Full Text Available Clinical evidence has shown that physical exercise during pregnancy may alter brain development and improve cognitive function of offspring. However, the mechanisms through which maternal exercise might promote such effects are not well understood. The present study examined levels of brain-derived neurotrophic factor (BDNF and absolute cell numbers in the hippocampal formation and cerebral cortex of rat pups born from mothers exercised during pregnancy. Additionally, we evaluated the cognitive abilities of adult offspring in different behavioral paradigms (exploratory activity and habituation in open field tests, spatial memory in a water maze test, and aversive memory in a step-down inhibitory avoidance task. Results showed that maternal exercise during pregnancy increased BDNF levels and absolute numbers of neuronal and non-neuronal cells in the hippocampal formation of offspring. No differences in BDNF levels or cell numbers were detected in the cerebral cortex. It was also observed that offspring from exercised mothers exhibited better cognitive performance in nonassociative (habituation and associative (spatial learning mnemonic tasks than did offspring from sedentary mothers. Our findings indicate that maternal exercise during pregnancy enhances offspring cognitive function (habituation behavior and spatial learning and increases BDNF levels and cell numbers in the hippocampal formation of offspring.

  15. Apurinic/Apyrimidinic Endonuclease 1 Upregulation Reduces Oxidative DNA Damage and Protects Hippocampal Neurons from Ischemic Injury

    OpenAIRE

    Leak, Rehana K.; Li, Peiying; Zhang, Feng; Sulaiman, Hassan H.; Weng, Zhongfang; Wang, Guohua; Stetler, R. Anne; Shi, Yejie; Cao, Guodong; Gao, Yanqin; Chen, Jun

    2015-01-01

    Aims: Apurinic/apyrimidinic endonuclease 1 (APE1) is a multifunctional enzyme that participates in base-excision repair of oxidative DNA damage and in the redox activation of transcription factors. We tested the hypothesis that APE1 upregulation protects neuronal structure and function against transient global cerebral ischemia (tGCI). Results: Upregulation of APE1 by low-dose proton irradiation (PI) or by transgene overexpression protected hippocampal CA1 neurons against tGCI-induced cell lo...

  16. Synaptic dysfunction, memory deficits and hippocampal atrophy due to ablation of mitochondrial fission in adult forebrain neurons.

    Science.gov (United States)

    Oettinghaus, B; Schulz, J M; Restelli, L M; Licci, M; Savoia, C; Schmidt, A; Schmitt, K; Grimm, A; Morè, L; Hench, J; Tolnay, M; Eckert, A; D'Adamo, P; Franken, P; Ishihara, N; Mihara, K; Bischofberger, J; Scorrano, L; Frank, S

    2016-01-01

    Well-balanced mitochondrial fission and fusion processes are essential for nervous system development. Loss of function of the main mitochondrial fission mediator, dynamin-related protein 1 (Drp1), is lethal early during embryonic development or around birth, but the role of mitochondrial fission in adult neurons remains unclear. Here we show that inducible Drp1 ablation in neurons of the adult mouse forebrain results in progressive, neuronal subtype-specific alterations of mitochondrial morphology in the hippocampus that are marginally responsive to antioxidant treatment. Furthermore, DRP1 loss affects synaptic transmission and memory function. Although these changes culminate in hippocampal atrophy, they are not sufficient to cause neuronal cell death within 10 weeks of genetic Drp1 ablation. Collectively, our in vivo observations clarify the role of mitochondrial fission in neurons, demonstrating that Drp1 ablation in adult forebrain neurons compromises critical neuronal functions without causing overt neurodegeneration.

  17. Somatodendritic and excitatory postsynaptic distribution of neuron-type dystrophin isoform, Dp40, in hippocampal neurons.

    Science.gov (United States)

    Fujimoto, Takahiro; Itoh, Kyoko; Yaoi, Takeshi; Fushiki, Shinji

    2014-09-12

    The Duchenne muscular dystrophy (DMD) gene produces multiple dystrophin (Dp) products due to the presence of several promoters. We previously reported the existence of a novel short isoform of Dp, Dp40, in adult mouse brain. However, the exact biochemical expression profile and cytological distribution of the Dp40 protein remain unknown. In this study, we generated a polyclonal antibody against the NH2-terminal region of the Dp40 and identified the expression profile of Dp40 in the mouse brain. Through an analysis using embryonic and postnatal mouse cerebrums, we found that Dp40 emerged from the early neonatal stages until adulthood, whereas Dp71, an another Dp short isoform, was highly detected in both prenatal and postnatal cerebrums. Intriguingly, relative expressions of Dp40 and Dp71 were prominent in cultured dissociated neurons and non-neuronal cells derived from mouse hippocampus, respectively. Furthermore, the immunocytological distribution of Dp40 was analyzed in dissociated cultured neurons, revealing that Dp40 is detected in the soma and its dendrites, but not in the axon. It is worthy to note that Dp40 is localized along the subplasmalemmal region of the dendritic shafts, as well as at excitatory postsynaptic sites. Thus, Dp40 was identified as a neuron-type Dp possibly involving dendritic and synaptic functions. Copyright © 2014 Elsevier Inc. All rights reserved.

  18. The aspirin metabolite salicylate enhances neuronal excitation in rat hippocampal CA1 area through reducing GABAergic inhibition.

    Science.gov (United States)

    Gong, Neng; Zhang, Min; Zhang, Xiao-Bing; Chen, Lin; Sun, Guang-Chun; Xu, Tian-Le

    2008-02-01

    Salicylate is the major metabolite and active component of aspirin (acetylsalicylic acid), which is widely used in clinical medicine for treating inflammation, pain syndromes and cardiovascular disorders. The well-known mechanism underlying salicylate's action mainly involves the inhibition of cyclooxygenase and subsequent decrease in prostaglandin production. Recent evidence suggests that salicylate also affects neuronal function through interaction with specific membrane channels/receptors. However, the effect of salicylate on synaptic and neural network function remains largely unknown. In this study, we investigated the effect of sodium salicylate on the synaptic transmission and neuronal excitation in the hippocampal CA1 area of rats, a key structure for many complex brain functions. With electrophysiological recordings in hippocampal slices, we found that sodium salicylate significantly enhanced neuronal excitation through reducing inhibitory GABAergic transmission without affecting the basal excitatory synaptic transmission. Salicylate significantly inhibited the amplitudes of both evoked and miniature inhibitory postsynaptic currents, and directly reduced gamma-aminobutyric acid type A (GABA(A)) receptor-mediated responses in cultured rat hippocampal neurons. Together, our results suggest that the widely used aspirin might impair hippocampal synaptic and neural network functions through its actions on GABAergic neurotransmission. Given the capability of aspirin to penetrate the blood-brain barrier, the present data imply that aspirin intake may cause network hyperactivity and be potentially harmful in susceptible subpopulations.

  19. 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…

  20. 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...

  1. Somatodendritic and excitatory postsynaptic distribution of neuron-type dystrophin isoform, Dp40, in hippocampal neurons

    Energy Technology Data Exchange (ETDEWEB)

    Fujimoto, Takahiro; Itoh, Kyoko, E-mail: kxi14@koto.kpu-m.ac.jp; Yaoi, Takeshi; Fushiki, Shinji

    2014-09-12

    Highlights: • Identification of dystrophin (Dp) shortest isoform, Dp40, is a neuron-type Dp. • Dp40 expression is temporally and differentially regulated in comparison to Dp71. • Somatodendritic and nuclear localization of Dp40. • Dp40 is localized to excitatory postsynapses. • Dp40 might play roles in dendritic and synaptic functions. - Abstract: The Duchenne muscular dystrophy (DMD) gene produces multiple dystrophin (Dp) products due to the presence of several promoters. We previously reported the existence of a novel short isoform of Dp, Dp40, in adult mouse brain. However, the exact biochemical expression profile and cytological distribution of the Dp40 protein remain unknown. In this study, we generated a polyclonal antibody against the NH{sub 2}-terminal region of the Dp40 and identified the expression profile of Dp40 in the mouse brain. Through an analysis using embryonic and postnatal mouse cerebrums, we found that Dp40 emerged from the early neonatal stages until adulthood, whereas Dp71, an another Dp short isoform, was highly detected in both prenatal and postnatal cerebrums. Intriguingly, relative expressions of Dp40 and Dp71 were prominent in cultured dissociated neurons and non-neuronal cells derived from mouse hippocampus, respectively. Furthermore, the immunocytological distribution of Dp40 was analyzed in dissociated cultured neurons, revealing that Dp40 is detected in the soma and its dendrites, but not in the axon. It is worthy to note that Dp40 is localized along the subplasmalemmal region of the dendritic shafts, as well as at excitatory postsynaptic sites. Thus, Dp40 was identified as a neuron-type Dp possibly involving dendritic and synaptic functions.

  2. Calcium-Activated Chloride Channels (CaCCs) Regulate Action Potential and Synaptic Response in Hippocampal Neurons

    Science.gov (United States)

    Huang, Wendy C.; Xiao, Shaohua; Huang, Fen; Harfe, Brian D.; Jan, Yuh Nung; Jan, Lily Yeh

    2012-01-01

    SUMMARY Central neurons respond to synaptic inputs from other neurons by generating synaptic potentials. Once the summated synaptic potentials reach threshold for action potential firing, the signal propagates leading to transmitter release at the synapse. The calcium influx accompanying such signaling opens calcium-activated ion channels for feedback regulation. Here we report a novel mechanism for modulating hippocampal neuronal signaling that involves calcium-activated chloride channels (CaCCs). We present the first evidence that CaCCs reside in hippocampal neurons and are in close proximity of calcium channels and NMDA receptors to shorten action potential duration, dampen excitatory synaptic potentials, impede temporal summation, and raise the threshold for action potential generation by synaptic potential. Having recently identified TMEM16A and TMEM16B as CaCCs, we further show that TMEM16B but not TMEM16A is important for hippocampal CaCC, laying the groundwork for deciphering the dynamic CaCC modulation of neuronal signaling in neurons important for learning and memory. PMID:22500639

  3. Abelson tyrosine kinase links PDGFbeta receptor activation to cytoskeletal regulation of NMDA receptors in CA1 hippocampal neurons

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    Beazely Michael A

    2008-12-01

    Full Text Available Abstract Background We have previously demonstrated that PDGF receptor activation indirectly inhibits N-methyl-D-aspartate (NMDA currents by modifying the cytoskeleton. PDGF receptor ligand is also neuroprotective in hippocampal slices and cultured neurons. PDGF receptors are tyrosine kinases that control a variety of signal transduction pathways including those mediated by PLCγ. In fibroblasts Src and another non-receptor tyrosine kinase, Abelson kinase (Abl, control PDGF receptor regulation of cytoskeletal dynamics. The mechanism whereby PDGF receptor regulates cytoskeletal dynamics in central neurons remains poorly understood. Results Intracellular applications of active Abl, but not heat-inactivated Abl, decreased NMDA-evoked currents in isolated hippocampal neurons. This mimics the effects of PDGF receptor activation in these neurons. The Abl kinase inhibitor, STI571, blocked the inhibition of NMDA currents by Abl. We demonstrate that PDGF receptors can activate Abl kinase in hippocampal neurons via mechanisms similar to those observed previously in fibroblasts. Furthermore, PDGFβ receptor activation alters the subcellular localization of Abl. Abl kinase is linked to actin cytoskeletal dynamics in many systems. We show that the inhibition of NMDA receptor currents by Abl kinase is blocked by the inclusion of the Rho kinase inhibitor, Y-27632, and that activation of Abl correlates with an increase in ROCK tyrosine phosphorylation. Conclusion This study demonstrates that PDGFβ receptors act via an interaction with Abl kinase and Rho kinase to regulated cytoskeletal regulation of NMDA receptor channels in CA1 pyramidal neurons.

  4. Long-term omega-3 supplementation modulates behavior, hippocampal fatty acid concentration, neuronal progenitor proliferation and central TNF-α expression in 7 month old unchallenged mice

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    Trent eGrundy

    2014-11-01

    Full Text Available Dietary polyunsaturated fatty acid (PUFA manipulation is being investigated as a potential therapeutic supplement to reduce the risk of developing age-related cognitive decline (ARCD. Animal studies suggest that high omega (Ω-3 and low Ω-6 dietary content reduces cognitive decline by decreasing central nervous system (CNS inflammation and modifying neuroimmune activity. However, no previous studies have investigated the long term effects of Ω-3 and Ω-6 dietary levels in healthy aging mice leaving the important question about the preventive effects of Ω-3 and Ω-6 on behavior and underlying molecular pathways unaddressed. We aimed to investigate the efficacy of long-term Ω-3 and Ω-6 PUFA dietary supplementation in mature adult C57BL/6 mice. We measured the effect of low, medium and high Ω-3:Ω-6 dietary ratio, given from the age of 3 to 7 months, on anxiety and cognition-like behavior, hippocampal tissue expression of TNF-α, markers of neuronal progenitor proliferation and gliogenesis and serum cytokine concentration. Our results show that a higher Ω-3:Ω-6 PUFA diet ratio increased hippocampal PUFA, increased anxiety, improved hippocampal dependent spatial memory and reduced hippocampal TNF-α levels compared to a low Ω-3:Ω-6 diet. Furthermore, serum TNF-α concentration was reduced in the higher Ω-3:Ω-6 PUFA ratio supplementation group while expression of the neuronal progenitor proliferation markers KI67 and doublecortin (DCX was increased in the dentate gyrus as opposed to the low Ω-3:Ω-6 group. Conversely, Ω-3:Ω-6 dietary PUFA ratio had no significant effect on astrocyte or microglia number or cell death in the dentate gyrus. These results suggest that supplementation of PUFAs may delay ageing effects on cognitive function in unchallenged mature adult C57BL/6 mice. This effect is possibly induced by increasing neuronal progenitor proliferation and reducing TNF-α.

  5. Long-term omega-3 supplementation modulates behavior, hippocampal fatty acid concentration, neuronal progenitor proliferation and central TNF-α expression in 7 month old unchallenged mice.

    Science.gov (United States)

    Grundy, Trent; Toben, Catherine; Jaehne, Emily J; Corrigan, Frances; Baune, Bernhard T

    2014-01-01

    Dietary polyunsaturated fatty acid (PUFA) manipulation is being investigated as a potential therapeutic supplement to reduce the risk of developing age-related cognitive decline (ARCD). Animal studies suggest that high omega (Ω)-3 and low Ω-6 dietary content reduces cognitive decline by decreasing central nervous system (CNS) inflammation and modifying neuroimmune activity. However, no previous studies have investigated the long term effects of Ω-3 and Ω-6 dietary levels in healthy aging mice leaving the important question about the preventive effects of Ω-3 and Ω-6 on behavior and underlying molecular pathways unaddressed. We aimed to investigate the efficacy of long-term Ω-3 and Ω-6 PUFA dietary supplementation in mature adult C57BL/6 mice. We measured the effect of low, medium, and high Ω-3:Ω-6 dietary ratio, given from the age of 3-7 months, on anxiety and cognition-like behavior, hippocampal tissue expression of TNF-α, markers of neuronal progenitor proliferation and gliogenesis and serum cytokine concentration. Our results show that a higher Ω-3:Ω-6 PUFA diet ratio increased hippocampal PUFA, increased anxiety, improved hippocampal dependent spatial memory and reduced hippocampal TNF-α levels compared to a low Ω-3:Ω-6 diet. Furthermore, serum TNF-α concentration was reduced in the higher Ω-3:Ω-6 PUFA ratio supplementation group while expression of the neuronal progenitor proliferation markers KI67 and doublecortin (DCX) was increased in the dentate gyrus as opposed to the low Ω-3:Ω-6 group. Conversely, Ω-3:Ω-6 dietary PUFA ratio had no significant effect on astrocyte or microglia number or cell death in the dentate gyrus. These results suggest that supplementation of PUFAs may delay aging effects on cognitive function in unchallenged mature adult C57BL/6 mice. This effect is possibly induced by increasing neuronal progenitor proliferation and reducing TNF-α.

  6. Long-term omega-3 supplementation modulates behavior, hippocampal fatty acid concentration, neuronal progenitor proliferation and central TNF-α expression in 7 month old unchallenged mice

    Science.gov (United States)

    Grundy, Trent; Toben, Catherine; Jaehne, Emily J.; Corrigan, Frances; Baune, Bernhard T.

    2014-01-01

    Dietary polyunsaturated fatty acid (PUFA) manipulation is being investigated as a potential therapeutic supplement to reduce the risk of developing age-related cognitive decline (ARCD). Animal studies suggest that high omega (Ω)-3 and low Ω-6 dietary content reduces cognitive decline by decreasing central nervous system (CNS) inflammation and modifying neuroimmune activity. However, no previous studies have investigated the long term effects of Ω-3 and Ω-6 dietary levels in healthy aging mice leaving the important question about the preventive effects of Ω-3 and Ω-6 on behavior and underlying molecular pathways unaddressed. We aimed to investigate the efficacy of long-term Ω-3 and Ω-6 PUFA dietary supplementation in mature adult C57BL/6 mice. We measured the effect of low, medium, and high Ω-3:Ω-6 dietary ratio, given from the age of 3–7 months, on anxiety and cognition-like behavior, hippocampal tissue expression of TNF-α, markers of neuronal progenitor proliferation and gliogenesis and serum cytokine concentration. Our results show that a higher Ω-3:Ω-6 PUFA diet ratio increased hippocampal PUFA, increased anxiety, improved hippocampal dependent spatial memory and reduced hippocampal TNF-α levels compared to a low Ω-3:Ω-6 diet. Furthermore, serum TNF-α concentration was reduced in the higher Ω-3:Ω-6 PUFA ratio supplementation group while expression of the neuronal progenitor proliferation markers KI67 and doublecortin (DCX) was increased in the dentate gyrus as opposed to the low Ω-3:Ω-6 group. Conversely, Ω-3:Ω-6 dietary PUFA ratio had no significant effect on astrocyte or microglia number or cell death in the dentate gyrus. These results suggest that supplementation of PUFAs may delay aging effects on cognitive function in unchallenged mature adult C57BL/6 mice. This effect is possibly induced by increasing neuronal progenitor proliferation and reducing TNF-α. PMID:25484856

  7. Propofol at Clinically Relevant Concentrations Increases Neuronal Differentiation but Is Not Toxic to Hippocampal Neural Precursor Cells In Vitro

    Science.gov (United States)

    Sall, Jeffrey W.; Stratmann, Greg; Leong, Jason; Woodward, Elliott; Bickler, Philip E.

    2012-01-01

    Background Propofol in the early postnatal period has been shown to cause brain cell death. One proposed mechanism for cognitive dysfunction after anesthesia is alteration of neural stem cell function and neurogenesis. We examined the effect of propofol on neural precursor or stem cells (NPCs) grown in vitro. Methods Hippocampal derived NPCs from postnatal day 2 rats were exposed to propofol or to Diprivan. NPCs were then analyzed for bromodeoxyuridine incorporation to measure proliferation. Cell death was measured by lactate dehydrogenase release. Immunocytochemistry was used to evaluate the expression of neuronal and glial markers in differentiating NPCs exposed to propofol. Results Propofol dose dependently increases the release of lactate dehydrogenase from NPCs under both proliferating and differentiating conditions at supraclinical concentrations (> 7.1μM). Both Diprivan and propofol had the same effect on NPCs. Propofol mediated release of lactate dehydrogenase is not inhibited by blocking the γ-aminobutyric acid type A receptor or extracellular calcium influx and is not mediated by caspase-3/7. Direct γ-aminobutyric acid type A receptor activation did not have the same effect. In differentiating NPCs 6 h of propofol at 2.1 μM increased the number neurons but not glial cells 4 days later. Increased neuronal differentiation was not blocked by Bicuculline. Conclusions Only supraclinical concentrations of propofol or Diprivan kill NPCs in culture by a non-γ-aminobutyric acid type A, noncaspase 3 mechanism. Clinically relevant doses of propofol increase neuronal fate choice by a non-γ-aminobutyric acid type A mechanism. PMID:23001052

  8. Inhibitory effects of brain-derived neurotrophic factor precursor on viability and neurite growth of murine hippocampal neurons

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    Jia CHEN

    2014-10-01

    Full Text Available Objective To explore the mediation effect of p75 neurotrophin receptor (p75NTR in the effect of brainderived neurotrophic factor precursor (proBDNF on viability and neurite growth of murine hippocampal neurons. Methods  Hippocampal neurons were obtained from p75NTR+/+ and p75NTR-/- 18-day mice and primarily cultured. For p75NTR+/+ neurons, three experimental groups were set, i.e. control, proBDNF (30ng/ml, and proBDNF (30ng/ml+p75/Fc (30µg/ml groups. For p75NTR-/- neurons, two experimental groups were set, i.e. control and proBDNF (30ng/ml groups. MTT assays were performed after 24h to examine the viability of neonatal primary neurons. Immunofluorescent staining was conducted after 72h to investigate the neurite length. Results With MAP2 and DAPI double fluorescent staining it was identified that the neonatal hippocampal neurons were successfully cultured in vitro with high purity. For viability assay of p75NTR+/+ neurons, it was found that the absorbance value at 570nm (A570 in proBDNF group was significantly lower than that in control group (P0.05. With neurite growth assay of p75NTR+/+ neurons, it was found that the neurite length in proBDNF group was significantly shorter than that in control group (P0.05. With neurite growth assay of p75NTR-/- neurons, no difference in neurite length was observed between proBDNF group and control group. Conclusion proBDNF may inhibit the neuronal viability and neurite growth via p75NTR. DOI: 10.11855/j.issn.0577-7402.2014.09.03

  9. GABAB receptor deficiency causes failure of neuronal homeostasis in hippocampal networks.

    Science.gov (United States)

    Vertkin, Irena; Styr, Boaz; Slomowitz, Edden; Ofir, Nir; Shapira, Ilana; Berner, David; Fedorova, Tatiana; Laviv, Tal; Barak-Broner, Noa; Greitzer-Antes, Dafna; Gassmann, Martin; Bettler, Bernhard; Lotan, Ilana; Slutsky, Inna

    2015-06-23

    Stabilization of neuronal activity by homeostatic control systems is fundamental for proper functioning of neural circuits. Failure in neuronal homeostasis has been hypothesized to underlie common pathophysiological mechanisms in a variety of brain disorders. However, the key molecules regulating homeostasis in central mammalian neural circuits remain obscure. Here, we show that selective inactivation of GABAB, but not GABA(A), receptors impairs firing rate homeostasis by disrupting synaptic homeostatic plasticity in hippocampal networks. Pharmacological GABA(B) receptor (GABA(B)R) blockade or genetic deletion of the GB(1a) receptor subunit disrupts homeostatic regulation of synaptic vesicle release. GABA(B)Rs mediate adaptive presynaptic enhancement to neuronal inactivity by two principle mechanisms: First, neuronal silencing promotes syntaxin-1 switch from a closed to an open conformation to accelerate soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex assembly, and second, it boosts spike-evoked presynaptic calcium flux. In both cases, neuronal inactivity removes tonic block imposed by the presynaptic, GB(1a)-containing receptors on syntaxin-1 opening and calcium entry to enhance probability of vesicle fusion. We identified the GB(1a) intracellular domain essential for the presynaptic homeostatic response by tuning intermolecular interactions among the receptor, syntaxin-1, and the Ca(V)2.2 channel. The presynaptic adaptations were accompanied by scaling of excitatory quantal amplitude via the postsynaptic, GB(1b)-containing receptors. Thus, GABA(B)Rs sense chronic perturbations in GABA levels and transduce it to homeostatic changes in synaptic strength. Our results reveal a novel role for GABA(B)R as a key regulator of population firing stability and propose that disruption of homeostatic synaptic plasticity may underlie seizure's persistence in the absence of functional GABA(B)Rs.

  10. Enhancement of information transmission with stochastic resonance in hippocampal CA1 neuron models.

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    Mino, Hiroyuki; Durand, Dominique M; Kawaguchi, Minato

    2006-01-01

    Stochastic resonance (SR) has been shown to enhance the signal to noise ratio or detection of signals in neurons. It is not yet clear how this effect of SR on the signal to noise ratio affects signal processing in neural networks. In this paper, we test the hypothesis that SR can improve information transmission in the hippocampus. From spike firing times recorded at the soma, the inter spike intervals were generated and then "total" and "noise" entropies were estimated to obtain the mutual information and information rate of the spike trains. The results show that the information rate reached a maximum value at a specific amplitude of the background noise, implying that the stochastic resonance can improve the information transmission in the CA1 neuron model. Furthermore, the results also show that the effect of stochastic resonance tended to decrease as the intensity of the random sub-threshold spike trains (signal) (more than 20 l/s) approached to that of the background noise (100 l/s). In conclusion, the computation results that the stochastic resonance can improve information processing in the hippocampal CA1 neuron model in which the intensity of the random sub-threshold spike trains was set at 5-20 l/s.

  11. Diverse Effects of an Acetylcholinesterase Inhibitor, Donepezil, on Hippocampal Neuronal Death after Pilocarpine-Induced Seizure.

    Science.gov (United States)

    Jeong, Jeong Hyun; Choi, Bo Young; Kho, A Ra; Lee, Song Hee; Hong, Dae Ki; Lee, Sang Hwon; Lee, Sang Yup; Song, Hong Ki; Choi, Hui Chul; Suh, Sang Won

    2017-11-02

    Epileptic seizures are short episodes of abnormal brain electrical activity. Many survivors of severe epilepsy display delayed neuronal death and permanent cognitive impairment. Donepezil is an acetylcholinesterase inhibitor and is an effective treatment agent for Alzheimer's disease. However, the role of donepezil in seizure-induced hippocampal injury remains untested. Temporal lobe epilepsy (TLE) was induced by intraperitoneal injection of pilocarpine (25 mg/kg). Donepezil (2.5 mg/kg/day) was administered by gavage in three different settings: (1) pretreatment for three days before the seizure; (2) for one week immediately after the seizure; and (3) for three weeks from three weeks after the seizure. We found that donepezil showed mixed effects on seizure-induced brain injury, which were dependent on the treatment schedule. Pretreatment with donepezil aggravated neuronal death, oxidative injury, and microglia activation. Early treatment with donepezil for one week showed neither adverse nor beneficial effects; however, a treatment duration of three weeks starting three weeks after the seizure showed a significant reduction in neuronal death, oxidative injury, and microglia activation. In conclusion, donepezil has therapeutic effects when injected for three weeks after seizure activity subsides. Therefore, the present study suggests that the therapeutic use of donepezil for epilepsy patients requires a well-conceived strategy for administration.

  12. Live-cell imaging of post-golgi transport vesicles in cultured hippocampal neurons

    DEFF Research Database (Denmark)

    Jensen, Camilla Stampe; Misonou, Hiroaki

    2015-01-01

    The subcellular localization of neuronal membrane signaling molecules such as receptors and ion channels depends on intracellular trafficking mechanisms. Essentially, vesicular trafficking mechanisms ensure that a large number of membrane proteins are correctly targeted to different subcellular c...

  13. 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.

  14. Branched dimerization of Tat peptide improves permeability to HeLa and hippocampal neuronal cells.

    Science.gov (United States)

    Monreal, I Abrrey; Liu, Qian; Tyson, Katherine; Bland, Tyler; Dalisay, Doralyn S; Adams, Erin V; Wayman, Gary A; Aguilar, Hector C; Saludes, Jonel P

    2015-03-28

    A dimeric branched peptide TATp-D designed as an analogue of the HIV-Tat protein transduction domain (TATp), a prototypical cell penetrating peptide (CPP), demonstrates significantly enhanced cell uptake at 0.25 to 2.5 μM. Live cell confocal laser scanning microscopy revealed that multivalency dramatically improved the permeation potency of TATp-D to HeLa and primary hippocampal neuronal cells. The observed enhanced ability of TATp-D to translocate through the membrane is highlighted by a non-linear dependence on concentration, exhibiting the greatest uptake at sub-micromolar concentrations as compared to TATp. Multimerization via bis-Fmoc Lysine offered a synthetically straightforward method to investigate the effects of multivalent CPPs while offering orthogonal handles for cargo attachment, increasing the utility of CPPs at significantly lower concentrations.

  15. Live-cell imaging of post-golgi transport vesicles in cultured hippocampal neurons.

    Science.gov (United States)

    Jensen, Camilla Stampe; Misonou, Hiroaki

    2015-01-01

    The subcellular localization of neuronal membrane signaling molecules such as receptors and ion channels depends on intracellular trafficking mechanisms. Essentially, vesicular trafficking mechanisms ensure that a large number of membrane proteins are correctly targeted to different subcellular compartments of neurons. In the past two decades, the establishment and advancement of fluorescent protein technology have provided us with opportunities to study how proteins are trafficked in living cells. However, live imaging of trafficking processes in neurons necessitate imaging tools to distinguish the several different routes that neurons use for protein trafficking. Here we provide a novel protocol to selectively visualize post-Golgi transport vesicles carrying fluorescent-labeled ion channel proteins in living neurons. Further, we provide a number of analytical tools we developed to quantify characteristics of different types of transport vesicles. We demonstrate the application of our protocol to investigate whether ion channels are sorted into distinct vesicular populations at the Golgi apparatus. We also demonstrate how these techniques are suitable for pharmacological dissection of the transport mechanisms by which post-Golgi vesicles are trafficked in neurons. Our protocol uniquely combines the classic temperature-block with close monitoring of the transient expression of transfected protein tagged with fluorescent proteins, and provides a quick and easy way to study protein trafficking in living neurons. We believe that the procedures described here are useful for researchers who are interested in studying molecular mechanisms of protein trafficking in neurons.

  16. Neurotoxicity of coral snake phospholipases A2 in cultured rat hippocampal neurons.

    Science.gov (United States)

    de Carvalho, Nathalia Delazeri; Garcia, Raphael CaioTamborelli; Ferreira, Adilson Kleber; Batista, Daniel Rodrigo; Cassola, Antonio Carlos; Maria, Durvanei; Lebrun, Ivo; Carneiro, Sylvia Mendes; Afeche, Solange Castro; Marcourakis, Tania; Sandoval, Maria Regina Lopes

    2014-03-13

    The neurotoxicity of two secreted Phospholipases A2 from Brazilian coral snake venom in rat primary hippocampal cell culture was investigated. Following exposure to Mlx-8 or Mlx-9 toxins, an increase in free cytosolic Ca(2+) and a reduction in mitochondrial transmembrane potential (ΔΨm) became evident and occurred prior to the morphological changes and cytotoxicity. Exposure of hippocampal neurons to Mlx-8 or Mlx-9 caused a decrease in the cell viability as assessed by MTT and LDH assays. Inspection using fluorescent images and ultrastructural analysis by scanning and transmission electron microscopy showed that multiphase injury is characterized by overlapping cell death phenotypes. Shrinkage, membrane blebbing, chromatin condensation, nucleosomal DNA fragmentation and the formation of apoptotic bodies were observed. The most striking alteration observed in the electron microscopy was the fragmentation and rarefaction of the neuron processes network. Degenerated terminal synapses, cell debris and apoptotic bodies were observed among the fragmented fibers. Numerous large vacuoles as well as swollen mitochondria and dilated Golgi were noted. Necrotic signs such as a large amount of cellular debris and membrane fragmentation were observed mainly when the cells were exposed to highest concentration of the PLA2-neurotoxins. PLA2s exposed cultures showed cytoplasmic vacuoles filled with cell debris, clusters of mitochondria presented mitophagy-like structures that are in accordance to patterns of programmed cell death by autophagy. Finally, we demonstrated that the sPLA2s, Mlx-8 and Mlx-9, isolated from the Micrurus lemniscatus snake venom induce a hybrid cell death with apoptotic, autophagic and necrotic features. Furthermore, this study suggests that the augment in free cytosolic Ca(2+) and mitochondrial dysfunction are involved in the neurotoxicity of Elapid coral snake venom sPLA2s. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. 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. Copyright © 2014. Published by Elsevier B.V.

  18. ESTIMATION OF THE NUMBER OF NEURONS IN THE HIPPOCAMPUS OF RATS WITH PENICILLIN INDUCED EPILEPSY

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    Ilgaz Akdogan

    2011-05-01

    Full Text Available Epilepsy is a neurological disease arising from strong and uncontrollable electrical firings of a group of neurons in the central nervous system. Experimental epileptic models have been developed to assess the physiopathology of epileptic seizures. This study was undertaken to estimate the number of neurons in the rat hippocampus with penicillin induced epilepsy, using a stereological method, "the optical fractionator". In the experimental group, 500 IU penicillin-G was injected intra-cortically, and in the control group, the same volume of saline was administered. A week later, the animals were decapitated and their brains were removed by craniatomy. Frozen brains were cut with a thickness of 150 ěm in a cryostat. Sections were collected by systematic random sampling and stained with hematoxylen-eosin. Microscopic images of pyramidal cell layers from hippocampus CA1, CA2 and CA3 subfields were then transferred to a monitor, using a 100x objective (N.A. = 1.25. Using the optical disector method, the neurons were counted in the frames and determined with a fractionator sampling scheme. The total pyramidal neuron number was then estimated using the optical fractionator method. The total pyramidal neuron number was found to be statistically lower in the experimental group (mean = 142,888 ± 11,745 than in the control group (mean = 177,953 ± 10,907 (p < 0.05. The results suggest that a decrease in the hippocampal neuronal number in a penicillin model of epilepsy can be determined objectively and efficiently using the optical fractionator method.

  19. Sleep deprivation causes memory deficits by negatively impacting neuronal connectivity in hippocampal area CA1

    Science.gov (United States)

    Havekes, Robbert; Park, Alan J; Tudor, Jennifer C; Luczak, Vincent G; Hansen, Rolf T; Ferri, Sarah L; Bruinenberg, Vibeke M; Poplawski, Shane G; Day, Jonathan P; Aton, Sara J; Radwańska, Kasia; Meerlo, Peter; Houslay, Miles D; Baillie, George S; Abel, Ted

    2016-01-01

    Brief periods of sleep loss have long-lasting consequences such as impaired memory consolidation. Structural changes in synaptic connectivity have been proposed as a substrate of memory storage. Here, we examine the impact of brief periods of sleep deprivation on dendritic structure. In mice, we find that five hours of sleep deprivation decreases dendritic spine numbers selectively in hippocampal area CA1 and increased activity of the filamentous actin severing protein cofilin. Recovery sleep normalizes these structural alterations. Suppression of cofilin function prevents spine loss, deficits in hippocampal synaptic plasticity, and impairments in long-term memory caused by sleep deprivation. The elevated cofilin activity is caused by cAMP-degrading phosphodiesterase-4A5 (PDE4A5), which hampers cAMP-PKA-LIMK signaling. Attenuating PDE4A5 function prevents changes in cAMP-PKA-LIMK-cofilin signaling and cognitive deficits associated with sleep deprivation. Our work demonstrates the necessity of an intact cAMP-PDE4-PKA-LIMK-cofilin activation-signaling pathway for sleep deprivation-induced memory disruption and reduction in hippocampal spine density. DOI: http://dx.doi.org/10.7554/eLife.13424.001 PMID:27549340

  20. Sleep deprivation causes memory deficits by negatively impacting neuronal connectivity in hippocampal area CA1.

    Science.gov (United States)

    Havekes, Robbert; Park, Alan J; Tudor, Jennifer C; Luczak, Vincent G; Hansen, Rolf T; Ferri, Sarah L; Bruinenberg, Vibeke M; Poplawski, Shane G; Day, Jonathan P; Aton, Sara J; Radwańska, Kasia; Meerlo, Peter; Houslay, Miles D; Baillie, George S; Abel, Ted

    2016-08-23

    Brief periods of sleep loss have long-lasting consequences such as impaired memory consolidation. Structural changes in synaptic connectivity have been proposed as a substrate of memory storage. Here, we examine the impact of brief periods of sleep deprivation on dendritic structure. In mice, we find that five hours of sleep deprivation decreases dendritic spine numbers selectively in hippocampal area CA1 and increased activity of the filamentous actin severing protein cofilin. Recovery sleep normalizes these structural alterations. Suppression of cofilin function prevents spine loss, deficits in hippocampal synaptic plasticity, and impairments in long-term memory caused by sleep deprivation. The elevated cofilin activity is caused by cAMP-degrading phosphodiesterase-4A5 (PDE4A5), which hampers cAMP-PKA-LIMK signaling. Attenuating PDE4A5 function prevents changes in cAMP-PKA-LIMK-cofilin signaling and cognitive deficits associated with sleep deprivation. Our work demonstrates the necessity of an intact cAMP-PDE4-PKA-LIMK-cofilin activation-signaling pathway for sleep deprivation-induced memory disruption and reduction in hippocampal spine density.

  1. Aluminum alters NMDA receptor 1A and 2A/B expression on neonatal hippocampal neurons in rats

    Directory of Open Access Journals (Sweden)

    Yuan Chia-Yi

    2011-11-01

    Full Text Available Abstract Background High aluminum (Al content in certain infant formula raises the concern of possible Al toxicity on brain development of neonates during their vulnerable period of growing. Results of in vivo study showed that Al content of brain tissues reached to 74 μM when oral intake up to 1110 μM, 10 times of that in the hi-Al infant formula. Methods Utilizing a cultured neuron cells in vitro model, we have assessed Al influence on neuronal specific gene expression alteration by immunoblot and immunohistochemistry and neural proliferation rate changes by MTT assay. Results Microscopic images showed that the neurite outgrowth of hippocampal neurons increased along with the Al dosages (37, 74 μM Al (AlCl3. MTT results also indicated that Al increased neural cell viability. On the other hand, the immunocytochemistry staining suggested that the protein expressions of NMDAR 1A and NMDAR 2A/B decreased with the Al dosages (p Conclusion Treated hippocampal neurons with 37 and 74 μM of Al for 14 days increased neural cell viability, but hampered NMDAR 1A and NMDAR 2A/B expressions. It was suggested that Al exposure might alter the development of hippocampal neurons in neonatal rats.

  2. Tat-HSP22 inhibits oxidative stress-induced hippocampal neuronal cell death by regulation of the mitochondrial pathway.

    Science.gov (United States)

    Jo, Hyo Sang; Kim, Dae Won; Shin, Min Jea; Cho, Su Bin; Park, Jung Hwan; Lee, Chi Hern; Yeo, Eun Ji; Choi, Yeon Joo; Yeo, Hyeon Ji; Sohn, Eun Jeong; Son, Ora; Cho, Sung-Woo; Kim, Duk-Soo; Yu, Yeon Hee; Lee, Keun Wook; Park, Jinseu; Eum, Won Sik; Choi, Soo Young

    2017-01-04

    Oxidative stress plays an important role in the progression of various neuronal diseases including ischemia. Heat shock protein 22 (HSP22) is known to protect cells against oxidative stress. However, the protective effects and mechanisms of HSP22 in hippocampal neuronal cells under oxidative stress remain unknown. In this study, we determined whether HSP22 protects against hydrogen peroxide (H2O2)-induced oxidative stress in HT-22 using Tat-HSP22 fusion protein. We found that Tat-HSP22 transduced into HT-22 cells and that H2O2-induced cell death, oxidative stress, and DNA damage were significantly reduced by Tat-HSP22. In addition, Tat-HSP22 markedly inhibited H2O2-induced mitochondrial membrane potential, cytochrome c release, cleaved caspase-3, and Bax expression levels, while Bcl-2 expression levels were increased in HT-22 cells. Further, we showed that Tat-HSP22 transduced into animal brain and inhibited cleaved-caspase-3 expression levels as well as significantly inhibited hippocampal neuronal cell death in the CA1 region of animals in the ischemic animal model. In the present study, we demonstrated that transduced Tat-HSP22 attenuates oxidative stress-induced hippocampal neuronal cell death through the mitochondrial signaling pathway and plays a crucial role in inhibiting neuronal cell death, suggesting that Tat-HSP22 protein may be used to prevent oxidative stress-related brain diseases including ischemia.

  3. Mdivi-1 Protects Epileptic Hippocampal Neurons from Apoptosis via Inhibiting Oxidative Stress and Endoplasmic Reticulum Stress in Vitro.

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    Xie, Nanchang; Wang, Cui; Wu, Chuanjie; Cheng, Xuan; Gao, Yanlun; Zhang, Haifeng; Zhang, Yi; Lian, Yajun

    2016-06-01

    Mitochondrial division inhibitor 1 (mdivi-1), a selective inhibitor of the mitochondrial fission protein dynamin-related protein 1, has been proposed to have a neuroprotective effect on hippocampal neurons in animal models of epilepsy. However, the effect of mdivi-1 on epileptic neuronal death in vitro remains unknown. Therefore, we investigated the effect of mdivi-1 and the underlying mechanisms in the hippocampal neuronal culture (HNC) model of acquired epilepsy (AE) in vitro. We found that mitochondrial fission was increased in the HNC model of AE and inhibition of mitochondrial fission by mdivi-1 significantly decreased neuronal apoptosis induced by AE. In addition, mdivi-1 pretreatment significantly attenuated oxidative stress induced by AE characterized by decrease of reactive oxygen species (ROS) production and malondialdehyde level and by increase of superoxide dismutase activity. Moreover, mdivi-1 pretreatment significantly decreased endoplasmic reticulum (ER) stress markers glucose-regulated protein 78, C/EBP homologous protein expression and caspase-3 activation. Altogether, our findings suggest that mdivi-1 protected against AE-induced hippocampal neuronal apoptosis in vitro via decreasing ROS-mediated oxidative stress and ER stress.

  4. 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.

  5. ATP induces NO production in hippocampal neurons by P2X(7 receptor activation independent of glutamate signaling.

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    Juan Francisco Codocedo

    Full Text Available To assess the putative role of adenosine triphosphate (ATP upon nitric oxide (NO production in the hippocampus, we used as a model both rat hippocampal slices and isolated hippocampal neurons in culture, lacking glial cells. In hippocampal slices, additions of exogenous ATP or 2'(3'-O-(4-Benzoylbenzoyl ATP (Bz-ATP elicited concentration-dependent NO production, which increased linearly within the first 15 min and plateaued thereafter; agonist EC50 values were 50 and 15 µM, respectively. The NO increase evoked by ATP was antagonized in a concentration-dependent manner by Coomassie brilliant blue G (BBG or by N(ω-propyl-L-arginine, suggesting the involvement of P2X7Rs and neuronal NOS, respectively. The ATP induced NO production was independent of N-methyl-D-aspartic acid (NMDA receptor activity as effects were not alleviated by DL-2-Amino-5-phosphonopentanoic acid (APV, but antagonized by BBG. In sum, exogenous ATP elicited NO production in hippocampal neurons independently of NMDA receptor activity.

  6. Nanomolar ouabain augments Ca2+ signalling in rat hippocampal neurones and glia

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    Song, Hong; Thompson, Scott M; Blaustein, Mordecai P

    2013-01-01

    Linkage of certain neurological diseases to Na+ pump mutations and some mood disorders to altered Na+ pump function has renewed interest in brain Na+ pumps. We tested nanomolar ouabain on Ca2+ signalling (fura-2) in rat hippocampal neurone–astrocyte co-cultures. The neurones and astrocytes express Na+ pumps with a high-ouabain-affinity catalytic subunit (α3 and α2, respectively); both also express pumps with a ouabain-resistant α1 subunit. Neurones and astrocytes were identified by immunocytochemistry and by stimulation; 3–4 μm l-glutamate (Glu) and 3 μm carbachol (CCh) evoked rapid Ca2+ transients only in neurones, and small, delayed transients in some astrocytes, whereas 0.5–1 μm ATP evoked Ca2+ transients only in astrocytes. Both cell types responded to 5–10 μm Glu or ATP. The signals evoked by 3–4 μm Glu in neurones were markedly inhibited by 3–10 μm MPEP (blocks metabotropic glutamate receptor mGluR5) and 10 μm LY341495 (non-selective mGluR blocker), but not by 80 μm AP5 (NMDA receptor blocker) or by selective block of mGluR1 or mGluR2. Pre-incubation (0.5–10 min) with 1–10 nm ouabain (EC50 neurones. This augmentation was abolished by a blocker of the Na+–Ca2+ exchanger, SEA0400 (300 nm). Ouabain (3 nm) pre-incubation also augmented 10 μm cyclopiazonic acid plus 10 mm caffeine-evoked release of Ca2+ from the neuronal endoplasmic reticulum (ER). The implication is that nanomolar ouabain inhibits α3 Na+ pumps, increases (local) intracellular Na+, and promotes Na+–Ca2+ exchanger-mediated Ca2+ gain and increased storage in the adjacent ER. Ouabain (3 nm) also increased ER Ca2+ release and enhanced 0.5 μm ATP-evoked transients in astrocytes; these effects were mediated by α2 Na+ pumps. Thus, nanomolar ouabain may strongly influence synaptic transmission in the brain as a result of its actions on the high-ouabain-affinity Na+ pumps in both neurones and astrocytes. The significance of these effects is heightened by the evidence that

  7. Pathological changes in hippocampal neuronal circuits underlie age-associated neurodegeneration and memory loss: positive clue toward SAD.

    Science.gov (United States)

    Moorthi, P; Premkumar, P; Priyanka, R; Jayachandran, K S; Anusuyadevi, M

    2015-08-20

    Among vertebrates hippocampus forms the major component of the brain in consolidating information from short-term memory to long-term memory. Aging is considered as the major risk factor for memory impairment in sporadic Alzheimer's disease (SAD) like pathology. Present study thus aims at investigating whether age-specific degeneration of neuronal-circuits in hippocampal formation (neural-layout of Subiculum-hippocampus proper-dentate gyrus (DG)-entorhinal cortex (EC)) results in cognitive impairment. Furthermore, the neuroprotective effect of Resveratrol (RSV) was attempted to study in the formation of hippocampal neuronal-circuits. Radial-Arm-Maze was conducted to evaluate hippocampal-dependent spatial and learning memory in control and experimental rats. Nissl staining of frontal cortex (FC), subiculum, hippocampal-proper (CA1→CA2→CA3→CA4), DG, amygdala, cerebellum, thalamus, hypothalamus, layers of temporal and parietal lobe of the neocortex were examined for pathological changes in young and aged wistar rats, with and without RSV. Hippocampal trisynaptic circuit (EC layerII→DG→CA3→CA1) forming new memory and monosynaptic circuit (EC→CA1) that strengthen old memories were found disturbed in aged rats. Loss of Granular neuron observed in DG and polymorphic cells of CA4 can lead to decreased mossy fibers disturbing neural-transmission (CA4→CA3) in perforant pathway. Further, intensity of nissl granules (stratum lacunosum moleculare (SLM)-SR-SO) of CA3 pyramidal neurons was decreased, disturbing the communication in schaffer collaterals (CA3-CA1) during aging. We also noticed disarranged neuronal cell layer in Subiculum (presubiculum (PrS)-parasubiculum (PaS)), interfering output from hippocampus to prefrontal cortex (PFC), EC, hypothalamus, and amygdala that may result in interruption of thought processes. We conclude from our observations that poor memory performance of aged rats as evidenced through radial arm maze (RAM) analysis was due to the

  8. Impaired rRNA synthesis triggers homeostatic responses in hippocampal neurons

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    Anna eKiryk

    2013-11-01

    Full Text Available Decreased rRNA synthesis and nucleolar disruption, known as nucleolar stress, are primary signs of cellular stress associated with aging and neurodegenerative disorders. Silencing of rDNA occurs during early stages of Alzheimer´s disease (AD and may play a role in dementia. Moreover aberrant regulation of the protein synthesis machinery is present in the brain of suicide victims and implicates the epigenetic modulation of rRNA. Recently, we developed unique mouse models characterized by nucleolar stress in neurons. We inhibited RNA polymerase I by genetic ablation of the basal transcription factor TIF-IA in adult hippocampal neurons. Nucleolar stress resulted in progressive neurodegeneration, although with a differential vulnerability within the CA1, CA3 and dentate gyrus. Here, we investigate the consequences of nucleolar stress on learning and memory. The mutant mice show normal performance in the Morris water maze and in other behavioral tests, suggesting the activation of adaptive mechanisms. In fact, we observe a significantly enhanced learning and re-learning corresponding to the initial inhibition of rRNA transcription. This phenomenon is accompanied by aberrant synaptic plasticity. By the analysis of nucleolar function and integrity, we find that the synthesis of rRNA is later restored. Gene expression profiling shows that thirty-six transcripts are differentially expressed in comparison to the control group in absence of neurodegeneration. Additionally, we observe a significant enrichment of the putative serum response factor (SRF binding sites in the promoters of the genes with changed expression, indicating potential adaptive mechanisms mediated by the mitogen-activated protein kinase pathway. In the dentate gyrus a neurogenetic response might compensate the initial molecular deficits. These results underscore the role of nucleolar stress in neuronal homeostasis and open a new ground for therapeutic strategies aiming at preserving

  9. Differential effects of cannabis extracts and pure plant cannabinoids on hippocampal neurones and glia.

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    Ryan, Duncan; Drysdale, Alison J; Pertwee, Roger G; Platt, Bettina

    2006-11-20

    We have shown previously that the plant cannabinoid cannabidiol (CBD) elevates intracellular calcium levels in both cultured hippocampal neurones and glia. Here, we investigated whether the main psychotropic constituent of cannabis, Delta(9)-tetrahydrocannabinol (THC) alone or in combination with other cannabis constituents can cause similar responses, and whether THC affects the responses induced by CBD. Our experiments were performed with 1 microM pure THC (pTHC), with 1 microM pure CBD (pCBD), with a high-THC, low CBD cannabis extract (eTHC), with a high-CBD, low THC cannabis extract (eCBD), with a mixture of eTHC and eCBD (THC:CBD=1:1) or with corresponding 'mock extracts' that contained only pTHC and pCBD mixed in the same proportion as in eTHC, eCBD or the 1:1 mixture of eTHC and eCBD. We detected significant differences in neurones both between the effects of pTHC and eTHC and between the effects of pCBD and eCBD. There were also differences between the Ca(2+) responses evoked in both neurones and glia by eTHC and mock eTHC, but not between eCBD and mock eCBD. A particularly striking observation was the much increased response size and maximal responder rates induced by the mixture of eTHC and eCBD than by the corresponding 1:1 mixture of pTHC and pCBD. Our data suggest that THC shares the ability of CBD to elevate Ca(2+) levels in neurones and glia, that THC and CBD interact synergistically and that the cannabis extracts have other constituents yet to be identified that can significantly modulate the ability of THC and CBD to raise Ca(2+) levels.

  10. Activation of the metabotropic glutamate receptor is neuroprotective during nitric oxide toxicity in primary hippocampal neurons of rats.

    Science.gov (United States)

    Maiese, K; Greenberg, R; Boccone, L; Swiriduk, M

    1995-07-21

    Metabotropic glutamate receptors (mGluRs) can influence neuronal survival and have been shown to be neuroprotective during glutamate toxicity in retinal cells and in cortical neurons. The mechanisms that mediate protection by this group of receptors are not clear. Since nitric oxide (NO) production can lead to neuronal cell death during excessive glutamate release, we examined whether neuronal survival was directly linked to mGluR activity and the NO pathway. Treatment with the mGluR4 receptor subtype agonist, L-(+)-2-amino-4-phosphonobutyric acid, in hippocampal cell cultures protected neurons during NO exposure. Treatment with L-(+)-2-amino-3-phosphonopropionic acid, an antagonist of the mGluR1 receptor subtype and inhibitor of inositol trisphosphate formation, did not significantly alter neuronal survival during NO administration. We conclude that activation of the mGluR4 receptor protects hippocampal neurons from NO toxicity and that the mechanism of NO induced neurodegeneration does not appear to involve inhibition of the mGluR1 receptor subtype activity or the phosphoinositide system.

  11. Altered balance of glutamatergic/GABAergic synaptic input and associated changes in dendrite morphology after BDNF expression in BDNF-deficient hippocampal neurons

    OpenAIRE

    Singh, B.; Henneberger, C.; Betances, D.; Arevalo, M.A.; Rodriguez-Tebar, A.; Meier, J.C.; Grantyn, R.

    2006-01-01

    Cultured neurons from bdnf-/- mice display reduced densities of synaptic terminals, although in vivo these deficits are small or absent. Here we aimed at clarifying the local responses to postsynaptic brain-derived neurotrophic factor (BDNF). To this end, solitary enhanced green fluorescent protein (EGFP)-labeled hippocampal neurons from bdnf-/- mice were compared with bdnf-/- neurons after transfection with BDNF, bdnf-/- neurons after transient exposure to exogenous BDNF, and bdnf+/+ neurons...

  12. Chondroitin Sulfate Induces Depression of Synaptic Transmission and Modulation of Neuronal Plasticity in Rat Hippocampal Slices

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    Elisa Albiñana

    2015-01-01

    Full Text Available It is currently known that in CNS the extracellular matrix is involved in synaptic stabilization and limitation of synaptic plasticity. However, it has been reported that the treatment with chondroitinase following injury allows the formation of new synapses and increased plasticity and functional recovery. So, we hypothesize that some components of extracellular matrix may modulate synaptic transmission. To test this hypothesis we evaluated the effects of chondroitin sulphate (CS on excitatory synaptic transmission, cellular excitability, and neuronal plasticity using extracellular recordings in the CA1 area of rat hippocampal slices. CS caused a reversible depression of evoked field excitatory postsynaptic potentials in a concentration-dependent manner. CS also reduced the population spike amplitude evoked after orthodromic stimulation but not when the population spikes were antidromically evoked; in this last case a potentiation was observed. CS also enhanced paired-pulse facilitation and long-term potentiation. Our study provides evidence that CS, a major component of the brain perineuronal net and extracellular matrix, has a function beyond the structural one, namely, the modulation of synaptic transmission and neuronal plasticity in the hippocampus.

  13. [Inhibition of sodium channels in acutely isolated hippocampal neurons by scorpion venom heat resistant protein].

    Science.gov (United States)

    Zhang, Xiao-Yun; Wang, Yue; Zhang, Jian; Wang, Jing-Yu; Zhao, Jie; Zhang, Wan-Qin; Li, Shao

    2007-06-25

    The effects of scorpion venom heat resistant protein (SVHRP) on sodium channel were studied in freshly isolated hippocampal neurons in rat using the whole-cell patch-clamp technique. The results indicated that tetrodotoxin-sensitive voltage-dependent sodium current in hippocampal neurons was inhibited by SVHRP in a dose-dependent manner. The half-inhibition concentration (IC(50)) was (0.0034+/-0.0004) microg/mL, Hill constant (n) was 0.4361+/-0.0318. After SVHRP application, a clear shift of the activation curve of Na(+) channel was shown towards more depolarized potential, resulting in channel opening at more positive membrane potentials. In the presence of 0.1 mug/mL SVHRP, the voltage for half-activation (V(1/2)) and the slope factor of the activation curve were (-23.96+/-0.41) mV and 3.73+/-0.08 (n=8, P<0.05) compared with the control recordings of (-34.38+/-0.62) mV and 4.52+/-0.52 (n=16), respectively. Averaged and normalized curve of steady-state inactivation of Na(+) channel was shifted towards negative potential after treatment of 0.1 and 0.01 mug/mL SVHRP. In the presence of 0.1 mug/mL SVHRP, the voltage for half-inactivation (V(1/2)) and the slope factor determined by a sigmoid fit of the inactivation curve were (-50.69+/-2.55) mV (n=8, P<0.01) and 5.49+/-0.72 (n=8, P<0.05) compared with the control recordings of (-32.60+/-1.52) mV and 6.73+/-0.51 (n=16), respectively. These results suggest that SVHRP blocks the voltage-dependent sodium currents and alters the sodium channel kinetics to decrease the excitability of neurons. This might be an interpretation for the antiepileptic effects of SVHRP.

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

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    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. Coordinated Scaling of Cortical and Cerebellar Numbers of Neurons

    Science.gov (United States)

    Herculano-Houzel, Suzana

    2010-01-01

    While larger brains possess concertedly larger cerebral cortices and cerebella, the relative size of the cerebral cortex increases with brain size, but relative cerebellar size does not. In the absence of data on numbers of neurons in these structures, this discrepancy has been used to dispute the hypothesis that the cerebral cortex and cerebellum function and have evolved in concert and to support a trend towards neocorticalization in evolution. However, the rationale for interpreting changes in absolute and relative size of the cerebral cortex and cerebellum relies on the assumption that they reflect absolute and relative numbers of neurons in these structures across all species – an assumption that our recent studies have shown to be flawed. Here I show for the first time that the numbers of neurons in the cerebral cortex and cerebellum are directly correlated across 19 mammalian species of four different orders, including humans, and increase concertedly in a similar fashion both within and across the orders Eulipotyphla (Insectivora), Rodentia, Scandentia and Primata, such that on average a ratio of 3.6 neurons in the cerebellum to every neuron in the cerebral cortex is maintained across species. This coordinated scaling of cortical and cerebellar numbers of neurons provides direct evidence in favor of concerted function, scaling and evolution of these brain structures, and suggests that the common notion that equates cognitive advancement with neocortical expansion should be revisited to consider in its stead the coordinated scaling of neocortex and cerebellum as a functional ensemble. PMID:20300467

  16. Coordinated scaling of cortical and cerebellar numbers of neurons

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    Suzana Herculano-Houzel

    2010-03-01

    Full Text Available While larger brains possess concertedly larger cerebral cortices and cerebella, the relative size of the cerebral cortex increases with brain size, but relative cerebellar size does not. In the absence of data on numbers of neurons in these structures, this discrepancy has been used to dispute the hypothesis that the cerebral cortex and cerebellum function and have evolved in concert and to support a trend towards neocorticalization in evolution. However, the rationale for interpreting changes in absolute and relative size of the cerebral cortex and cerebellum relies on the assumption that they reflect absolute and relative numbers of neurons in these structures across all species – an assumption that our recent studies have shown to be flawed. Here I show for the first time that the numbers of neurons in the cerebral cortex and cerebellum are directly correlated across 19 mammalian species of 4 different orders, including humans, and increase concertedly in a similar fashion both within and across the orders Eulipotyphla (Insectivora, Rodentia, Scandentia and Primata, such that on average a ratio of 3.6 neurons in the cerebellum to every neuron in the cerebral cortex is maintained across species. This coordinated scaling of cortical and cerebellar numbers of neurons provides direct evidence in favor of concerted function, scaling and evolution of these brain structures, and suggests that the common notion that equates cognitive advancement with neocortical expansion should be revisited to consider in its stead the coordinated scaling of neocortex and cerebellum as a functional ensemble.

  17. Recording Spikes Activity in Cultured Hippocampal Neurons Using Flexible or Transparent Graphene Transistors

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    Farida Veliev

    2017-08-01

    Full Text Available The emergence of nanoelectronics applied to neural interfaces has started few decades ago, and aims to provide new tools for replacing or restoring disabled functions of the nervous systems as well as further understanding the evolution of such complex organization. As the same time, graphene and other 2D materials have offered new possibilities for integrating micro and nano-devices on flexible, transparent, and biocompatible substrates, promising for bio and neuro-electronics. In addition to many bio-suitable features of graphene interface, such as, chemical inertness and anti-corrosive properties, its optical transparency enables multimodal approach of neuronal based systems, the electrical layer being compatible with additional microfluidics and optical manipulation ports. The convergence of these fields will provide a next generation of neural interfaces for the reliable detection of single spike and record with high fidelity activity patterns of neural networks. Here, we report on the fabrication of graphene field effect transistors (G-FETs on various substrates (silicon, sapphire, glass coverslips, and polyimide deposited onto Si/SiO2 substrates, exhibiting high sensitivity (4 mS/V, close to the Dirac point at VLG < VD and low noise level (10−22 A2/Hz, at VLG = 0 V. We demonstrate the in vitro detection of the spontaneous activity of hippocampal neurons in-situ-grown on top of the graphene sensors during several weeks in a millimeter size PDMS fluidics chamber (8 mm wide. These results provide an advance toward the realization of biocompatible devices for reliable and high spatio-temporal sensing of neuronal activity for both in vitro and in vivo applications.

  18. Action-potential discharge in hippocampal CA1 pyramidal neurons: current source-density analysis.

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    Richardson, T L; Turner, R W; Miller, J J

    1987-11-01

    1. The site of origin of evoked action-potential discharge in hippocampal CA1 pyramidal neurons was investigated using the in vitro rat hippocampal slice preparation. 2. Action-potential discharge in pyramidal cells was evoked by stimulation of efferent pyramidal cell fibers in the alveus (antidromic) or afferent synaptic inputs in stratum oriens (SO) or stratum radiatum (SR). Laminar profiles of evoked extracellular field potentials were recorded at 25-micron intervals along the entire dendrosomatic axis of the pyramidal cell and a one-dimensional current source-density analysis was applied. 3. Suprathreshold stimulation of the alveus evoked an antidromic population spike response and current sink with the shortest peak latency in stratum pyramidale or proximal stratum oriens. A biphasic positive/negative potential associated with a current source/sink was recorded in dendritic regions, with both components increasing in peak latency with distance from the border of stratum pyramidale. 4. Suprathreshold stimulation of SO or SR evoked a population spike response superimposed upon the underlying synaptic depolarization at all levels of the dendrosomatic axis. The shortest latency population spike and current sink were recorded in stratum pyramidale or proximal stratum oriens. In dendritic regions, a biphasic positive/negative potential and current source/sink conducted with increasing latency from the border of stratum pyramidale. 5. A direct comparison of alvear- and SR-evoked responses revealed a basic similarity in population spike potentials and associated sink/source relationships at both the somatic and dendritic level and a similar shift in peak latency of spike components along the pyramidal cell axis. 6. It is concluded that the initial site for generation of a spike along the dendrosomatic axis of the pyramidal cell following antidromic or orthodromic stimulation is in the region of the cell body layer (soma or axon hillock). Action-potential discharge in

  19. The Effects of Acute and Chronic Ethanol Exposure on Presynaptic and Postsynaptic GABAA Receptor Function in Cultured Cortical and Hippocampal Neurons

    Science.gov (United States)

    Fleming, Rebekah L.; Manis, Paul B.; Morrow, A. Leslie

    2009-01-01

    Decades after ethanol was first described as a GABA mimetic, the precise mechanisms that produce the acute effects of ethanol and the physiological adaptations that underlie ethanol tolerance and dependence remain unclear. While a substantial body of evidence suggests that ethanol acts on GABAergic neurotransmission to enhance inhibition in the CNS, the precise mechanisms underlying the physiological effects of both acute and chronic ethanol exposure are still under investigation. We have used in vitro ethanol exposure followed by recording of miniature inhibitory postsynaptic currents (mIPSCs) to determine whether acute or chronic ethanol exposure directly alters synaptic GABAA receptor function or GABA release in cultured cortical and hippocampal neurons. Acute ethanol exposure slightly increased the duration of mIPSCs in hippocampal neurons but did not alter mIPSC kinetics in cortical neurons. Acute ethanol exposure did not change mIPSC frequency in either hippocampal or cortical neurons. One day of chronic ethanol exposure produced a transient decrease in mIPSC duration in cortical neurons but did not alter mIPSC kinetics in hippocampal neurons. Chronic ethanol exposure did not change mIPSC frequency in either hippocampal or cortical neurons. Chronic ethanol exposure also did not produce substantial cross-tolerance to a benzodiazepine in either hippocampal or cortical neurons. The results suggest that ethanol exposure in vitro has limited effects on synaptic GABAAR function and action-potential independent GABA release in cultured neurons and suggests that ethanol exposure in cultured cortical and hippocampal neurons may not reproduce all of the effects that occur in vivo and in acute brain slices. PMID:20004338

  20. BDNF-induced nitric oxide signals in cultured rat hippocampal neurons: time course, mechanism of generation, and effect on neurotrophin secretion

    OpenAIRE

    Kolarow, Richard; Kuhlmann, Christoph R. W.; Munsch, Thomas; Zehendner, Christoph; Brigadski, Tanja; Luhmann, Heiko J.; Lessmann, Volkmar

    2014-01-01

    BDNF and nitric oxide signaling both contribute to plasticity at glutamatergic synapses. However, the role of combined signaling of both pathways at the same synapse is largely unknown. Using NO imaging with diaminofluoresceine in cultured hippocampal neurons we analyzed the time course of neurotrophin-induced NO signals. Application of exogenous BDNF, NT-4, and NT-3 (but not NGF) induced NO signals in the soma and in proximal dendrites of hippocampal neurons that were sensitive to NO synthas...

  1. BDNF-induced nitric oxide signals in cultured rat hippocampal neurons: time course, mechanism of generation, and effect on neurotrophin secretion

    OpenAIRE

    Richard eKolarow; Richard eKolarow; Christoph eKuhlmann; Thomas eMunsch; Christoph eZehendner; Tanja eBrigadski; Tanja eBrigadski; Heiko J Luhmann; Volkmar eLessmann; Volkmar eLessmann

    2014-01-01

    BDNF and nitric oxide signaling both contribute to plasticity at glutamatergic synapses. However the role of combined signaling of both pathways at the same synapse is largely unknown. Using NO imaging with diaminofluoresceine in cultured hippocampal neurons we analyzed the time course of neurotrophin induced NO signals. Application of exogenous BDNF, NT-4, and NT-3 (but not NGF) induced NO signals in the soma and in proximal dendrites of hippocampal neurons that were sensitive to NO synthase...

  2. ALTERED HIPPOCAMPAL NEUROGENESIS AND AMYGDALAR NEURONAL ACTIVITY IN ADULT MICE WITH REPEATED EXPERIENCE OF AGGRESSION

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    Dmitriy eSmagin

    2015-12-01

    Full Text Available The repeated experience of winning in a social conflict setting elevates levels of aggression and may lead to violent behavioral patterns. Here we use a paradigm of repeated aggression and fighting deprivation to examine changes in behavior, neurogenesis, and neuronal activity in mice with positive fighting experience. We show that for males, repeated positive fighting experience induces persistent demonstration of aggression and stereotypic behaviors in daily agonistic interactions, enhances aggressive motivation, and elevates levels of anxiety. When winning males are deprived of opportunities to engage in further fights, they demonstrate increased levels of aggressiveness. Positive fighting experience results in increased levels of progenitor cell proliferation and production of young neurons in the hippocampus. This increase is not diminished after a fighting deprivation period. Furthermore, repeated winning experience decreases the number of activated (c-fos positive cells in the basolateral amygdala and increases the number of activated cells in the hippocampus; a subsequent no-fight period restores the number of c-fos-positive cells. Our results indicate that extended positive fighting experience in a social conflict heightens aggression, increases proliferation of neuronal progenitors and production of young neurons in the hippocampus, and decreases neuronal activity in the amygdala; these changes can be modified by depriving the winners of the opportunity for further fights.

  3. Development of potent fluorescent polyamine toxins and application in labeling of ionotropic glutamate receptors in hippocampal neurons

    DEFF Research Database (Denmark)

    Nørager, Niels Grøn; Jensen, Christel Barker; Rathje, Mette

    2013-01-01

    subtypes. Here, we have exploited these analogues as templates in the development of fluorescent iGlu receptor ligands to be employed as unique tools for dynamic studies. Eighteen fluorescent analogues were designed and synthesized, and subsequently pharmacologically evaluated at three iGlu receptor...... of the photophysical properties of the incorporated fluorophores. Finally, we demonstrate the applicability of the developed probes for imaging of iGlu receptors in hippocampal neurons....

  4. Oligomeric forms of the metastasis-related Mts1 (S100A4) protein stimulate neuronal differentiation in cultures of rat hippocampal neurons

    DEFF Research Database (Denmark)

    Novitskaya, V; Grigorian, M; Kriajevska, M

    2000-01-01

    Neuronal differentiation and axonal growth are controlled by a variety of factors including neurotrophic factors, extracellular matrix components, and cell adhesion molecules. Here we describe a novel and very efficient neuritogenic factor, the metastasis-related Mts1 protein, belonging to the S100...... protein family. The oligomeric but not the dimeric form of Mts1 strongly induces differentiation of cultured hippocampal neurons. A mutant with a single Y75F amino acid substitution, which stabilizes the dimeric form of Mts1, is unable to promote neurite extension. Disulfide bonds do not play an essential...

  5. Molecular mechanisms of non-transferrin-bound and transferring-bound iron uptake in primary hippocampal neurons.

    Science.gov (United States)

    Ji, Changyi; Kosman, Daniel J

    2015-06-01

    The molecular mechanisms of iron trafficking in neurons have not been elucidated. In this study, we characterized the expression and localization of ferrous iron transporters Zip8, Zip14 and divalent metal transporter 1 (DMT1), and ferrireductases Steap2 and stromal cell-derived receptor 2 in primary rat hippocampal neurons. Steap2 and Zip8 partially co-localize, indicating these two proteins may function in Fe(3+) reduction prior to Fe(2+) permeation. Zip8, DMT1, and Steap2 co-localize with the transferrin receptor/transferrin complex, suggesting they may be involved in transferrin receptor/transferrin-mediated iron assimilation. In brain interstitial fluid, transferring-bound iron (TBI) and non-transferrin-bound iron (NTBI) exist as potential iron sources. Primary hippocampal neurons exhibit significant iron uptake from TBI (Transferrin-(59) Fe(3+)) and NTBI, whether presented as (59) Fe(2+) -citrate or (59) Fe(3+) -citrate; reductase-independent (59) Fe(2+) uptake was the most efficient uptake pathway of the three. Kinetic analysis of Zn(2+) inhibition of Fe(2+) uptake indicated that DMT1 plays only a minor role in the uptake of NTBI. In contrast, localization and knockdown data indicate that Zip8 makes a major contribution. Data suggest also that cell accumulation of (59) Fe from TBI relies at least in part on an endocytosis-independent pathway. These data suggest that Zip8 and Steap2 play a major role in iron accumulation from NTBI and TBI by hippocampal neurons. Analysis of the expression and localization of known iron uptake transporters demonstrated that Zip8 makes a major contribution to iron accumulation in primary cultures of rat embryonic hippocampal neurons. These cells exhibit uptake pathways for ferrous and ferric iron (non-transferrin-bound iron, NTBI in figure) and for transferrin-bound iron; the ferrireductases Steap2 and SDR2 support the uptake of ferric iron substrates. Zip8 and Steap2 are strongly expressed in the plasma membrane of both soma

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

    Science.gov (United States)

    De-Paula, Vanessa de Jesus; Kerr, Daniel Shikanai; de Carvalho, Marília Palma Fabiano; Schaeffer, Evelin Lisete; Talib, Leda Leme; Gattaz, Wagner Farid; Forlenza, Orestes Vicente

    2015-11-04

    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. 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). 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). 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. 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.

  7. 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

  8. Hippocampal neuronal metal ion imbalance related oxidative stress in a rat model of chronic aluminum exposure and neuroprotection of meloxicam

    Science.gov (United States)

    2014-01-01

    Neurodegenerative diseases remain a significant unresolved societal burden afflicting millions of people worldwide. Neurons in the brain are highly sensitive to oxidative stress, which can be induced by metal toxicity. In this paper, a chronic aluminum overload-induced model of neurodegeneration was used to investigate whether metal ions (Al, Fe, Mn, Cu and Zn)-related oxidative stress was involved in neurodegenerative mechanism and to identify the protective action of meloxicam against rat hippocampal neuronal injury. The metal ion contents, activity of superoxide dismutase (SOD), and content of malondialdehyde (MDA) were detected. The results showed that the spatial learning and memory (SLM) function was significantly impaired in chronic aluminum overload rats. Considerable karyopycnosis was observed in hippocampal neurons. The SOD activity was weakened and the MDA content increased both significantly. In the hippocampus, Al, Fe, Mn, Cu, and Zn contents increased by 184.1%, 186.1%, 884.2%, 199.4% and 149.2%, respectively. Meloxicam administration (without Al) had no effect compared with the control group, while meloxicam treatment with aluminum exposure significantly protected rats from SLM function impairment, neuron death, lower SOD activity, higher MDA content and brain metal ion imbalance. Our findings suggest that the cerebral metal ion imbalance-related oxidative stress is involved in mechanism of cerebral injury and neurodegeneration induced by chronic Al overload in rats, and that meloxicam protects neurons by reducing metal ion imbalance-related oxidative stress. PMID:24618126

  9. The possible consequences for cognitive functions of external electric fields at power line frequency on hippocampal CA1 pyramidal neurons.

    Science.gov (United States)

    Migliore, Rosanna; De Simone, Giada; Leinekugel, Xavier; Migliore, Michele

    2017-04-01

    The possible effects on cognitive processes of external electric fields, such as those generated by power line pillars and household appliances are of increasing public concern. They are difficult to study experimentally, and the relatively scarce and contradictory evidence make it difficult to clearly assess these effects. In this study, we investigate how, why and to what extent external perturbations of the intrinsic neuronal activity, such as those that can be caused by generation, transmission and use of electrical energy can affect neuronal activity during cognitive processes. For this purpose, we used a morphologically and biophysically realistic three-dimensional model of CA1 pyramidal neurons. The simulation findings suggest that an electric field oscillating at power lines frequency, and environmentally measured strength, can significantly alter both the average firing rate and temporal spike distribution properties of a hippocampal CA1 pyramidal neuron. This effect strongly depends on the specific and instantaneous relative spatial location of the neuron with respect to the field, and on the synaptic input properties. The model makes experimentally testable predictions on the possible functional consequences for normal hippocampal functions such as object recognition and spatial navigation. The results suggest that, although EF effects on cognitive processes may be difficult to occur in everyday life, their functional consequences deserve some consideration, especially when they constitute a systematic presence in living environments. © 2016 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  10. Volume regulated anion channel currents of rat hippocampal neurons and their contribution to oxygen-and-glucose deprivation induced neuronal death.

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    Huaqiu Zhang

    2011-02-01

    Full Text Available Volume-regulated anion channels (VRAC are widely expressed chloride channels that are critical for the cell volume regulation. In the mammalian central nervous system, the physiological expression of neuronal VRAC and its role in cerebral ischemia are issues largely unknown. We show that hypoosmotic medium induce an outwardly rectifying chloride conductance in CA1 pyramidal neurons in rat hippocampal slices. The induced chloride conductance was sensitive to some of the VRAC inhibitors, namely, IAA-94 (300 µM and NPPB (100 µM, but not to tamoxifen (10 µM. Using oxygen-and-glucose deprivation (OGD to simulate ischemic conditions in slices, VRAC activation appeared after OGD induced anoxic depolarization (AD that showed a progressive increase in current amplitude over the period of post-OGD reperfusion. The OGD induced VRAC currents were significantly inhibited by inhibitors for glutamate AMPA (30 µM NBQX and NMDA (40 µM AP-5 receptors in the OGD solution, supporting the view that induction of AD requires an excessive Na(+-loading via these receptors that in turn to activate neuronal VRAC. In the presence of NPPB and DCPIB in the post-OGD reperfusion solution, the OGD induced CA1 pyramidal neuron death, as measured by TO-PRO-3-I staining, was significantly reduced, although DCPIB did not appear to be an effective neuronal VRAC blocker. Altogether, we show that rat hippocampal pyramidal neurons express functional VRAC, and ischemic conditions can initial neuronal VRAC activation that may contribute to ischemic neuronal damage.

  11. Erythropoietin and carbamylated erythropoietin promote histone deacetylase 5 phosphorylation and nuclear export in rat hippocampal neurons

    Energy Technology Data Exchange (ETDEWEB)

    Jo, Hye-Ryeong [Department of Biomedical Sciences, Graduate School of Biomedical Science and Engineering (Korea, Republic of); Kim, Yong-Seok [Department of Biomedical Sciences, Graduate School of Biomedical Science and Engineering (Korea, Republic of); Department of Biochemistry and Molecular Biology, College of Medicine, Hanyang University, 17 Haengdang-dong, Sungdong-gu, Seoul 133-791 (Korea, Republic of); Son, Hyeon, E-mail: hyeonson@hanyang.ac.kr [Department of Biomedical Sciences, Graduate School of Biomedical Science and Engineering (Korea, Republic of); Department of Biochemistry and Molecular Biology, College of Medicine, Hanyang University, 17 Haengdang-dong, Sungdong-gu, Seoul 133-791 (Korea, Republic of)

    2016-01-29

    Erythropoietin (EPO) produces neurotrophic effects in animal model of neurodegeneration. However, clinical use of EPO is limited due to thrombotic risk. Carbamylated EPO (cEPO), devoid of thrombotic risk, has been proposed as a novel neuroprotective and neurotrophic agent although the molecular mechanisms of cEPO remain incomplete. Here, we show a previously unidentified role of histone deacetylase 5 (HDAC5) in the actions of EPO and cEPO. EPO and cEPO regulate the HDAC5 phosphorylation at two critical sites, Ser259 and Ser498 through a protein kinase D (PKD) dependent pathway. In addition, EPO and cEPO rapidly stimulates nuclear export of HDAC5 in rat hippocampal neurons which expressing HDAC5-GFP. Consequently, EPO and cEPO enhanced the myocyte enhancer factor-2 (MEF2) target gene expression. Taken together, our results reveal that EPO and cEPO mediate MEF2 target gene expression via the regulation of HDAC5 phosphorylation at Ser259/498, and suggest that HDAC5 could be a potential mechanism contributing to the therapeutic actions of EPO and cEPO.

  12. Nicotine Uses Neuron-Glia Communication to Enhance Hippocampal Synaptic Transmission and Long-term Memory

    Science.gov (United States)

    López-Hidalgo, Mónica; Salgado-Puga, Karla; Alvarado-Martínez, Reynaldo; Medina, Andrea Cristina; Prado-Alcalá, Roberto A.; García-Colunga, Jesús

    2012-01-01

    Nicotine enhances synaptic transmission and facilitates long-term memory. Now it is known that bi-directional glia-neuron interactions play important roles in the physiology of the brain. However, the involvement of glial cells in the effects of nicotine has not been considered until now. In particular, the gliotransmitter D-serine, an endogenous co-agonist of NMDA receptors, enables different types of synaptic plasticity and memory in the hippocampus. Here, we report that hippocampal long-term synaptic plasticity induced by nicotine was annulled by an enzyme that degrades endogenous D-serine, or by an NMDA receptor antagonist that acts at the D-serine binding site. Accordingly, both effects of nicotine: the enhancement of synaptic transmission and facilitation of long-term memory were eliminated by impairing glial cells with fluoroacetate, and were restored with exogenous D-serine. Together, these results show that glial D-serine is essential for the long-term effects of nicotine on synaptic plasticity and memory, and they highlight the roles of glial cells as key participants in brain functions. PMID:23185511

  13. Pinacidil and levamisole prevent glutamate-induced death of hippocampal neuronal cells through reducing ROS production.

    Science.gov (United States)

    Shukry, Mustafa; Kamal, Tarek; Ali, Radi; Farrag, Foad; Almadaly, Essam; Saleh, Ayman A; Abu El-Magd, Mohammed

    2015-10-01

    Activators of both adenosine 5'-triphosphate (ATP)-sensitive K(+) (KATP) channel and cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channel have significant in vivo and in vitro neuroprotection against glutamate-induced death of some neuronal cells. Here, the effect of the KATP channel activator, pinacidil, and the CFTR Cl(-) channel opener, levamisole, against glutamate-induced oxidative stress were investigated in mouse hippocampal cells, HT22. The results from cell viability assay (WST-1) showed that pinacidil and levamisole weakly protected cells against glutamate-induced toxicity at 10 μM and their effect increased in a dose-dependent manner till reach maximum protection at 300 μM. Pretreatment with pinacidil or levamisole significantly suppressed the elevation of reactive oxygen species (ROS) triggered by glutamate through stabilising mitochondrial membrane potential and subsequently protected HT22 cells against glutamate-induced death. HT22 cells viability was maintained by pinacidil and levamisole in presence of glutathione inhibitor, BSO. Also, pinacidil and levamisole pretreatment did not induce recovery of glutathione levels decreased by glutamate Expectedly, this protection was abolished by the KATP and CFTR Cl(-) channels blocker, glibenclamide. Thus, both pinacidil and levamisole protect HT22 cells against glutamate-induced cell death through stabilising mitochondrial membrane potential and subsequently decreasing ROS production.

  14. Rutin attenuates ethanol-induced neurotoxicity in hippocampal neuronal cells by increasing aldehyde dehydrogenase 2.

    Science.gov (United States)

    Song, Kibbeum; Kim, Sokho; Na, Ji-Young; Park, Jong-Heum; Kim, Jae-Kyung; Kim, Jae-Hun; Kwon, Jungkee

    2014-10-01

    Rutin is derived from buckwheat, apples, and black tea. It has been shown to have beneficial anti-inflammatory and antioxidant effects. Ethanol is a central nervous system depressant and neurotoxin. Its metabolite, acetaldehyde, is critically toxic. Aldehyde dehydrogenase 2 (ALDH2) metabolizes acetaldehyde into nontoxic acetate. This study examined rutin's effects on ALDH2 activity in hippocampal neuronal cells (HT22 cells). Rutin's protective effects against acetaldehyde-based ethanol neurotoxicity were confirmed. Daidzin, an ALDH2 inhibitor, was used to clarify the mechanisms of rutin's protective effects. Cell viability was significantly increased after rutin treatment. Rutin significantly reversed ethanol-increased Bax, cytochrome c expression and caspase 3 activity, and decreased Bcl-2 and Bcl-xL protein expression in HT22 cells. Interestingly, rutin increased ALDH2 expression, while daidzin reversed this beneficial effect. Thus, this study demonstrates rutin protects HT22 cells against ethanol-induced neurotoxicity by increasing ALDH2 activity. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Dendritic mRNAs encode diversified functionalities in hippocampal pyramidal neurons

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    Bloch Lisa M

    2006-02-01

    Full Text Available Abstract Background Targeted transport of messenger RNA and local protein synthesis near the synapse are important for synaptic plasticity. In order to gain an overview of the composition of the dendritic mRNA pool, we dissected out stratum radiatum (dendritic lamina from rat hippocampal CA1 region and compared its mRNA content with that of stratum pyramidale (cell body layer using a set of cDNA microarrays. RNAs that have over-representation in the dendritic fraction were annotated and sorted into function groups. Results We have identified 154 dendritic mRNA candidates, which can be arranged into the categories of receptors and channels, signaling molecules, cytoskeleton and adhesion molecules, and factors that are involved in membrane trafficking, in protein synthesis, in posttranslational protein modification, and in protein degradation. Previously known dendritic mRNAs such as MAP2, calmodulin, and G protein gamma subunit were identified from our screening, as were mRNAs that encode proteins known to be important for synaptic plasticity and memory, such as spinophilin, Pumilio, eEF1A, and MHC class I molecules. Furthermore, mRNAs coding for ribosomal proteins were also found in dendrites. Conclusion Our results suggest that neurons transport a variety of mRNAs to dendrites, not only those directly involved in modulating synaptic plasticity, but also others that play more common roles in cellular metabolism.

  16. 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.

    2014-01-01

    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. PMID:24695716

  17. Centella asiatica (L. Leaf Extract Treatment During the Growth Spurt Period Enhances Hippocampal CA3 Neuronal Dendritic Arborization in Rats

    Directory of Open Access Journals (Sweden)

    K. G. Mohandas Rao

    2006-01-01

    Full Text Available Centella asiatica (CeA is a creeping plant growing in damp places in India and other Asian countries. The leaves of CeA are used for memory enhancement in the Ayurvedic system of medicine, an alternative system of medicine in India. In this study, we have investigated the effect during the rat growth spurt period of CeA fresh leaf extract treatment on the dendritic morphology of hippocampal CA3 neurons, one of the regions of the brain concerned with learning and memory. Neonatal rat pups (7 days old were fed with 2, 4 or 6 ml kg−1 body weight of fresh leaf extract of CeA for 2, 4 or 6 weeks. After the treatment period the rats were killed, their brains were removed and the hippocampal neurons were impregnated with silver nitrate (Golgi staining. Hippocampal CA3 neurons were traced using a camera lucida, and dendritic branching points (a measure of dendritic arborization and intersections (a measure of dendritic length were quantified. These data were compared with data for age-matched control rats. The results showed a significant increase in the dendritic length (intersections and dendritic branching points along the length of both apical and basal dendrites in rats treated with 4 and 6 ml kg−1 body weight per day of CeA for longer periods of time (i.e. 4 and 6 weeks. We conclude that the constituents/active principles present in CeA fresh leaf extract have a neuronal dendritic growth stimulating property; hence, the extract can be used for enhancing neuronal dendrites in stress and neurodegenerative and memory disorders.

  18. Effects of blast overpressure on neurons and glial cells in rat organotypic hippocampal slice cultures

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    Anna P Miller

    2015-02-01

    Full Text Available Due to recent involvement in military conflicts, and an increase in the use of explosives, there has been an escalation in the incidence of blast-induced traumatic brain injury (bTBI among US military personnel. Having a better understanding of the cellular and molecular cascade of events in bTBI is prerequisite for the development of an effective therapy that currently is unavailable. The present study utilized organotypic hippocampal slice cultures (OHCs exposed to blast overpressures of 150 kPa (low and 280 kPa (high as an in vitro bTBI model. Using this model we further characterized the cellular effects of the blast injury. Blast-evoked cell death was visualized by a propidium iodide (PI uptake assay as early as 2 h post-injury. Quantification of PI staining in the cornu Ammonis 1 and 3 (CA1 and CA3 and the dentate gyrus (DG regions of the hippocampus at 2, 24, 48, and 72 h following blast exposure revealed significant time dependent effects. OHCs exposed to 150 kPa demonstrated a slow increase in cell death plateauing between 24 and 48 h, while OHCs from the high blast group exhibited a rapid increase in cell death already at 2 h, peaking at approximately 24 h post-injury. Measurements of lactate dehydrogenase (LDH release into the culture medium also revealed a significant increase in cell lysis in both low and high blast groups compared to sham controls. OHCs were fixed at 72 h post-injury and immunostained for markers against neurons, astrocytes, and microglia. Labeling OHCs with PI, neuronal, and glial markers revealed that the blast evoked extensive neuronal death and to a lesser extent loss of glial cells. Furthermore, our data demonstrated activation of astrocytes and microglia cells in low and high blasted OHCs, which reached a statistically significant difference in the high blast group. These data confirmed that our in vitro bTBI model is a useful tool for studying cellular and molecular changes after blast exposure.

  19. Neurons in the hippocampal CA1 region, but not the dentate gyrus, are susceptible to oxidative stress in rats with streptozotocin-induced type 1 diabetes

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    Sang Gun Lee

    2015-01-01

    Full Text Available In this study, we investigated the effects of streptozotocin-induced type 1 diabetes on antioxidant-like protein-1 immunoreactivity, protein carbonyl levels, and malondialdehyde formation, a marker for lipid peroxidation, in the hippocampus. For this study, streptozotocin (75 mg/kg was intraperitoneally injected into adult rats to induce type 1 diabetes. The three experimental parameters were determined at 2, 3, 4 weeks after streptozotocin treatment. Fasting blood glucose levels significantly increased by 20.7-21.9 mM after streptozotocin treatment. The number of antioxidant-like protein-1 immunoreactive neurons significantly decreased in the hippocampal CA1 region, but not the dentate gyrus, 3 weeks after streptozotocin treatment compared to the control group. Malondialdehyde and protein carbonyl levels, which are modified by oxidative stress, significantly increased with a peak at 3 weeks after malondialdehyde treatment, and then decreased 4 weeks after malondialdehyde treatment. These results suggest that neurons in the hippocampal CA1 region, but not the dentate gyrus, are susceptible to oxidative stress 3 weeks after malondialdehyde treatment.

  20. Action potential changes associated with the inhibitory effects on voltage-gated sodium current of hippocampal CA1 neurons by silver nanoparticles.

    Science.gov (United States)

    Liu, Zhaowei; Ren, Guogang; Zhang, Tao; Yang, Zhuo

    2009-10-29

    Nano-sized materials are now being used in medicine, biotechnology, energy, and environmental technology. Although a wide and growing number of applications for nanomaterials exist, there are limited studies available on toxicity of nanoparticles for their human risk and environmental assessment. The aim of this study was to investigate the effects of silver nanoparticles (nano-Ag) on voltage-activated sodium currents in hippocampal CA1 neurons. Nano-Ag was tested at increasing concentrations (10(-6), 5 x 10(-6), 10(-5) g/ml). The research results showed that only nano-Ag (10(-5) g/ml) reduced the amplitude of voltage-gated sodium current (I(Na)). The nano-Ag particles produced a hyperpolarizing shift in the activation-voltage curve of I(Na) and also delayed the recovery of I(Na) from inactivation. Action potential properties and the pattern of repetitive firing were examined using whole cell current-clamp recordings. Peak amplitude and overshoot of the evoked single action potential were decreased and half-width was increased in the present of the 10(-5) g/ml nano-Ag solution, and the firing rate of repetitive firing had no change. The results suggest that nano-Ag may alter the action potential of hippocampal CA1 neurons by depressing voltage-gated sodium current.

  1. Calcium signals can freely cross the nuclear envelope in hippocampal neurons: somatic calcium increases generate nuclear calcium transients

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    Bading Hilmar

    2007-07-01

    Full Text Available Abstract Background In hippocampal neurons, nuclear calcium signaling is important for learning- and neuronal survival-associated gene expression. However, it is unknown whether calcium signals generated by neuronal activity at the cell membrane and propagated to the soma can unrestrictedly cross the nuclear envelope to invade the nucleus. The nuclear envelope, which allows ion transit via the nuclear pore complex, may represent a barrier for calcium and has been suggested to insulate the nucleus from activity-induced cytoplasmic calcium transients in some cell types. Results Using laser-assisted uncaging of caged calcium compounds in defined sub-cellular domains, we show here that the nuclear compartment border does not represent a barrier for calcium signals in hippocampal neurons. Although passive diffusion of molecules between the cytosol and the nucleoplasm may be modulated through changes in conformational state of the nuclear pore complex, we found no evidence for a gating mechanism for calcium movement across the nuclear border. Conclusion Thus, the nuclear envelope does not spatially restrict calcium transients to the somatic cytosol but allows calcium signals to freely enter the cell nucleus to trigger genomic events.

  2. Calcium signals can freely cross the nuclear envelope in hippocampal neurons: somatic calcium increases generate nuclear calcium transients

    Science.gov (United States)

    Eder, Anja; Bading, Hilmar

    2007-01-01

    Background In hippocampal neurons, nuclear calcium signaling is important for learning- and neuronal survival-associated gene expression. However, it is unknown whether calcium signals generated by neuronal activity at the cell membrane and propagated to the soma can unrestrictedly cross the nuclear envelope to invade the nucleus. The nuclear envelope, which allows ion transit via the nuclear pore complex, may represent a barrier for calcium and has been suggested to insulate the nucleus from activity-induced cytoplasmic calcium transients in some cell types. Results Using laser-assisted uncaging of caged calcium compounds in defined sub-cellular domains, we show here that the nuclear compartment border does not represent a barrier for calcium signals in hippocampal neurons. Although passive diffusion of molecules between the cytosol and the nucleoplasm may be modulated through changes in conformational state of the nuclear pore complex, we found no evidence for a gating mechanism for calcium movement across the nuclear border. Conclusion Thus, the nuclear envelope does not spatially restrict calcium transients to the somatic cytosol but allows calcium signals to freely enter the cell nucleus to trigger genomic events. PMID:17663775

  3. The microtubule destabilizing protein stathmin controls the transition from dividing neuronal precursors to postmitotic neurons during adult hippocampal neurogenesis

    NARCIS (Netherlands)

    Boekhoorn, Karin; van Dis, Vera; Goedknegt, Erika; Sobel, André; Lucassen, Paul J; Hoogenraad, Casper C

    2014-01-01

    The hippocampus is one of the two areas in the mammalian brain where adult neurogenesis occurs. Adult neurogenesis is well known to be involved in hippocampal physiological functions as well as pathophysiological conditions. Microtubules (MTs), providing intracellular transport, stability, and

  4. Clathrin assembly protein AP180 and CALM differentially control axogenesis and dendrite outgrowth in embryonic hippocampal neurons.

    Science.gov (United States)

    Bushlin, Ittai; Petralia, Ronald S; Wu, Fangbai; Harel, Asaff; Mughal, Mohamed R; Mattson, Mark P; Yao, Pamela J

    2008-10-08

    Emerging data suggest that, much like epithelial cells, the polarized growth of neurons requires both the secretory and endocytic pathways. The clathrin assembly proteins AP180 and CALM (clathrin assembly lymphoid myeloid protein) are known to be involved in clathrin-mediated endocytosis, but their roles in mammalian neurons and, in particular, in developmental processes before synaptogenesis are unknown. Here we provide evidence that AP180 and CALM play critical roles in establishing the polarity and controlling the growth of axons and dendrites in embryonic hippocampal neurons. Knockdown of AP180 primarily impairs axonal development, whereas reducing CALM levels results in dendritic dystrophy. Conversely, neurons that overexpress AP180 or CALM generate multiple axons. Ultrastructural analysis shows that CALM affiliates with a wider range of intracellular trafficking organelles than does AP180. Functional analysis shows that endocytosis is reduced in both AP180-deficient and CALM-deficient neurons. Additionally, CALM-deficient neurons show disrupted secretory transport. Our data demonstrate previously unknown functions for AP180 and CALM in intracellular trafficking that are essential in the growth of neurons.

  5. Astrocytic Ca(2+) waves mediate activation of extrasynaptic NMDA receptors in hippocampal neurons to aggravate brain damage during ischemia.

    Science.gov (United States)

    Dong, Qi-Ping; He, Jing-Quan; Chai, Zhen

    2013-10-01

    Excitotoxicity plays a central role in the neuronal damage during ischemic stroke. Although growing evidence suggests that activation of extrasynaptic NMDA receptors initiates neuronal death, no direct evidence demonstrated their activation during ischemia. Using rat hippocampal slices, we detected oxygen-glucose deprivation (OGD) induced slow inward currents (SICs) mediated by extrasynaptic NMDA receptors in CA1 pyramidal neurons. Moreover, Ca(2+) chelator BAPTA dialysis into astrocytic network decreased the frequency of OGD induced SICs, indicating that the activation of extrasynaptic NMDA receptors depended on astrocytic Ca(2+) activity. To further demonstrate the importance of astrocytic Ca(2+) activity, we tested hippocampal slices from inositol triphosphate receptor type 2 (IP3R2) knock-out mice which abolished the astrocytic Ca(2+) activity. As expected, the frequency of OGD induced SICs was reduced. Using two-photon Ca(2+) imaging, we characterized the astrocytic Ca(2+) dynamics. By controlling Ca(2+) level in the individual astrocytes using targeted photolysis, we found that OGD facilitated the propagation of intercellular Ca(2+) waves, which were inhibited by gap junction blocker carbenoxolone (CBX). CBX also inhibited the Ca(2+) activity of the astrocytic network and decreased the SIC frequency during OGD. Functionally, the infarct volumes from brain ischemia were reduced in IP3R2 knock-out mice and in rat intracerebrally delivered with CBX. Our results demonstrate that enhanced Ca(2+) activity of the astrocytic network plays a key role on the activation of extrasynaptic NMDA receptors in hippocampal neurons, which enhances brain damage during ischemia. Copyright © 2013 Elsevier Inc. All rights reserved.

  6. Two cell circuits of oriented adult hippocampal neurons on self-assembled monolayers for use in the study of neuronal communication in a defined system.

    Science.gov (United States)

    Edwards, Darin; Stancescu, Maria; Molnar, Peter; Hickman, James J

    2013-08-21

    In this study, we demonstrate the directed formation of small circuits of electrically active, synaptically connected neurons derived from the hippocampus of adult rats through the use of engineered chemically modified culture surfaces that orient the polarity of the neuronal processes. Although synaptogenesis, synaptic communication, synaptic plasticity, and brain disease pathophysiology can be studied using brain slice or dissociated embryonic neuronal culture systems, the complex elements found in neuronal synapses makes specific studies difficult in these random cultures. The study of synaptic transmission in mature adult neurons and factors affecting synaptic transmission are generally studied in organotypic cultures, in brain slices, or in vivo. However, engineered neuronal networks would allow these studies to be performed instead on simple functional neuronal circuits derived from adult brain tissue. Photolithographic patterned self-assembled monolayers (SAMs) were used to create the two-cell "bidirectional polarity" circuit patterns. This pattern consisted of a cell permissive SAM, N-1[3-(trimethoxysilyl)propyl] diethylenetriamine (DETA), and was composed of two 25 μm somal adhesion sites connected with 5 μm lines acting as surface cues for guided axonal and dendritic regeneration. Surrounding the DETA pattern was a background of a non-cell-permissive poly(ethylene glycol) (PEG) SAM. Adult hippocampal neurons were first cultured on coverslips coated with DETA monolayers and were later passaged onto the PEG-DETA bidirectional polarity patterns in serum-free medium. These neurons followed surface cues, attaching and regenerating only along the DETA substrate to form small engineered neuronal circuits. These circuits were stable for more than 21 days in vitro (DIV), during which synaptic connectivity was evaluated using basic electrophysiological methods.

  7. Early postnatal exposure to isoflurane causes cognitive deficits and disrupts development of newborn hippocampal neurons via activation of the mTOR pathway.

    Science.gov (United States)

    Kang, Eunchai; Jiang, Danye; Ryu, Yun Kyoung; Lim, Sanghee; Kwak, Minhye; Gray, Christy D; Xu, Michael; Choi, Jun H; Junn, Sue; Kim, Jieun; Xu, Jing; Schaefer, Michele; Johns, Roger A; Song, Hongjun; Ming, Guo-Li; Mintz, C David

    2017-07-01

    Clinical and preclinical studies indicate that early postnatal exposure to anesthetics can lead to lasting deficits in learning and other cognitive processes. The mechanism underlying this phenomenon has not been clarified and there is no treatment currently available. Recent evidence suggests that anesthetics might cause persistent deficits in cognitive function by disrupting key events in brain development. The hippocampus, a brain region that is critical for learning and memory, contains a large number of neurons that develop in the early postnatal period, which are thus vulnerable to perturbation by anesthetic exposure. Using an in vivo mouse model we demonstrate abnormal development of dendrite arbors and dendritic spines in newly generated dentate gyrus granule cell neurons of the hippocampus after a clinically relevant isoflurane anesthesia exposure conducted at an early postnatal age. Furthermore, we find that isoflurane causes a sustained increase in activity in the mechanistic target of rapamycin pathway, and that inhibition of this pathway with rapamycin not only reverses the observed changes in neuronal development, but also substantially improves performance on behavioral tasks of spatial learning and memory that are impaired by isoflurane exposure. We conclude that isoflurane disrupts the development of hippocampal neurons generated in the early postnatal period by activating a well-defined neurodevelopmental disease pathway and that this phenotype can be reversed by pharmacologic inhibition.

  8. Pharmacological characterization of emerging synthetic cannabinoids in HEK293T cells and hippocampal neurons.

    Science.gov (United States)

    Costain, Willard J; Tauskela, Joseph S; Rasquinha, Ingrid; Comas, Tanya; Hewitt, Melissa; Marleau, Vincent; Soo, Evelyn C

    2016-09-05

    There has been a worldwide proliferation of synthetic cannabinoids that have become marketed as legal alternatives to cannabis (marijuana). Unfortunately, there is a dearth of information about the pharmacological effects of many of these emerging synthetic cannabinoids (ESCs), which presents a challenge for regulatory authorities that need to take such scientific evidence into consideration in order to regulate ECSs as controlled substances. We aimed to characterize the pharmacological properties of ten ESCs using two cell based assays that enabled the determination of potency and efficacy relative to a panel of well-characterized cannabinoids. Agonist-mediated inhibition of forskolin-stimulated cyclic adenosine monophosphate (cAMP) levels was monitored in live HEK293T cells transfected with human cannabinoid receptor 1 gene (CNR1) and pGloSensor-22F. Pharmacological analysis of this data indicated that all of the ESCs tested were full agonists, with the following rank order of potency: Win 55212-2≈5F-PB-22≈AB-PINACA≈EAM-2201≈MAM-2201>JWH-250≈ PB-22>AKB48 N-(5FP)>AKB-48≈STS-135>XLR-11. Assessment of agonist-stimulated depression of Ca(2+) transients was also used to confirm the efficacy of five ESCs (XLR-11, JWH-250, AB-PINACA, 5F-PB-22, and MAM-2201) in cultured primary hippocampal neurons. This work aims to help inform decisions made by regulatory agencies concerned with the profusion of these poorly characterized recreational drugs. Copyright © 2016. Published by Elsevier B.V.

  9. Tuning local calcium availability: cell-type-specific immobile calcium buffer capacity in hippocampal neurons.

    Science.gov (United States)

    Matthews, Elizabeth A; Schoch, Susanne; Dietrich, Dirk

    2013-09-04

    It has remained difficult to ascribe a specific functional role to immobile or fixed intracellular calcium buffers in central neurons because the amount of these buffers is unknown. Here, we explicitly isolated the fixed buffer fraction by prolonged whole-cell patch-clamp dialysis and quantified its buffering capacity in murine hippocampal slices using confocal calcium imaging and the "added-buffer" approach. In dentate granule cells, the calcium binding ratio (κ) after complete washout of calbindin D28k (Cb), κfixed, displayed a substantial value of ∼100. In contrast, in CA1 oriens lacunosum moleculare (OLM) interneurons, which do not contain any known calcium-binding protein(s), κfixed amounted to only ∼30. Based on these values, a theoretical analysis of dendritic spread of calcium after local entry showed that fixed buffers, in the absence of mobile species, decrease intracellular calcium mobility 100- and 30-fold in granule cells and OLM cells, respectively, and thereby strongly slow calcium signals. Although the large κfixed alone strongly delays the spread of calcium in granule cells, this value optimizes the benefits of additionally expressing the mobile calcium binding protein Cb. With such high κfixed, Cb effectively increases the propagation velocity to levels seen in OLM cells and, contrary to expectation, does not affect the peak calcium concentration close to the source but sharpens the spatial and temporal calcium gradients. The data suggest that the amount of fixed buffers determines the temporal availability of calcium for calcium-binding partners and plays a pivotal role in setting the repertoire of cellular calcium signaling regimens.

  10. Information in small neuronal ensemble activity in the hippocampal CA1 during delayed non-matching to sample performance in rats

    Directory of Open Access Journals (Sweden)

    Takahashi Susumu

    2009-09-01

    Full Text Available Abstract Background The matrix-like organization of the hippocampus, with its several inputs and outputs, has given rise to several theories related to hippocampal information processing. Single-cell electrophysiological studies and studies of lesions or genetically altered animals using recognition memory tasks such as delayed non-matching-to-sample (DNMS tasks support the theories. However, a complete understanding of hippocampal function necessitates knowledge of the encoding of information by multiple neurons in a single trial. The role of neuronal ensembles in the hippocampal CA1 for a DNMS task was assessed quantitatively in this study using multi-neuronal recordings and an artificial neural network classifier as a decoder. Results The activity of small neuronal ensembles (6-18 cells over brief time intervals (2-50 ms contains accurate information specifically related to the matching/non-matching of continuously presented stimuli (stimulus comparison. The accuracy of the combination of neurons pooled over all the ensembles was markedly lower than those of the ensembles over all examined time intervals. Conclusion The results show that the spatiotemporal patterns of spiking activity among cells in the small neuronal ensemble contain much information that is specifically useful for the stimulus comparison. Small neuronal networks in the hippocampal CA1 might therefore act as a comparator during recognition memory tasks.

  11. 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 (Plead exposure. Oxidative stress thus contributes to lead neurotoxicity but other pathogenic mechanisms are also involved. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Activation of extrasynaptic GABA(A) receptors inhibits cyclothiazide-induced epileptiform activity in hippocampal CA1 neurons.

    Science.gov (United States)

    Wan, Li; Liu, Xu; Wu, Zheng; Ren, Wanting; Kong, Shuzhen; Dargham, Raya Abou; Cheng, Longzhen; Wang, Yun

    2014-10-01

    Extrasynaptic GABA(A) receptors (GABA(A)Rs)-mediated tonic inhibition is reported to involve in the pathogenesis of epilepsy. In this study, we used cyclothiazide (CTZ)-induced in vitro brain slice seizure model to explore the effect of selective activation of extrasynaptic GABA(A)Rs by 4,5,6,7-tetrahydroisoxazolo[5,4-c] pyridine-3-ol (THIP) on the CTZ-induced epileptiform activity in hippocampal neurons. Perfusion with CTZ dose-dependently induced multiple epileptiform peaks of evoked population spikes (PSs) in CA1 pyramidal neurons, and treatment with THIP (5 μmol/L) significantly reduced the multiple PS peaks induced by CTZ stimulation. Western blot showed that the δ-subunit of the GABA(A)R, an extrasynaptic specific GABA(A)R subunit, was also significantly down-regulated in the cell membrane 2 h after CTZ treatment. Our results suggest that the CTZ-induced epileptiform activity in hippocampal CA1 neurons is suppressed by the activation of extrasynaptic GABA(A)Rs, and further support the hypothesis that tonic inhibition mediated by extrasynaptic GABA(A)Rs plays a prominent role in seizure generation.

  13. Imaging of evoked dense-core-vesicle exocytosis in hippocampal neurons reveals long latencies and kiss-and-run fusion events

    OpenAIRE

    Xia, Xiaofeng; Lessmann, Volkmar; Martin, Thomas F. J.

    2008-01-01

    Evoked neuropeptide secretion in the central nervous system occurs slowly, but the basis for slow release is not fully understood. Whereas exocytosis of single synaptic vesicles in neurons and of dense-core vesicles (DCVs) in endocrine cells have been directly visualized, single DCV exocytic events in neurons of the central nervous system have not been previously studied. We imaged DCV exocytosis in primary cultured hippocampal neurons using fluorescent propeptide carg...

  14. Interplay between Dopamine and γ2- AminoButyric Acid type A receptors' surface dynamics during maturation of neurons and development of hippocampal networks.

    OpenAIRE

    Matias, Miguel Albino

    2015-01-01

    MATIAS, Miguel Albino - Interplay between Dopamine and γ2- AminoButyric Acid type A receptors' surface dynamics during maturation of neurons and development of hippocampal networks. Coimbra : [s.n.], 2015. Dissertação de Mestrado em Biologia Celular e Molecular. A dynamic synapse is crucial not only in the regulation of synaptic transmission but also for maturation and development of neurons and neuronal circuits. This is particularly important in the case of receptors, whic...

  15. Computer aided solution for segmenting the neuron line in hippocampal microscope images

    Science.gov (United States)

    Albaidhani, Tahseen; Jassim, Sabah; Al-Assam, Hisham

    2017-05-01

    The brain Hippocampus component is known to be responsible for memory and spatial navigation. Its functionality depends on the status of different blood vessels within the Hippocampus and is severely impaired by Alzheimer's disease as a result blockage of increasing number of blood vessels by accumulation of amyloid-beta (Aβ) protein. Accurate counting of blood vessels within the Hippocampus of mice brain, from microscopic images, is an active research area for the understanding of Alzheimer's disease. Here, we report our work on automatic detection of the Region of Interest, i.e. the region in which blood vessels are located. This area typically falls between the hippocampus edge and the line of neurons within the Hippocampus. This paper proposes a new method to detect and exclude the neuron line to improve the accuracy of blood vessel counting because some neurons on it might lead to false positive cases as they look like blood vessels. Our proposed solution is based on using trainable segmentation approach with morphological operations, taking into account variation in colour, intensity values, and image texture. Experiments on a sufficient number of microscopy images of mouse brain demonstrate the effectiveness of the developed solution in preparation for blood vessels counting.

  16. Nucleoli numbers and neuronal growth in supraoptic nucleus neurons during postnatal development in the rat.

    Science.gov (United States)

    Crespo, D; Viadero, C F; Villegas, J; Lafarga, M

    1988-11-01

    We present a quantitative study of the variations in the number of nucleoli in supraoptic nucleus neurons during the postnatal period, as well as a morphometric and stereological analysis of the nuclear and cytoplasmic volume changes of these maturing neurons. The mean number of nucleoli per cell was 1.59 +/- 0.28 (mean +/- S.D.) at P1; it then began to decrease until P14 (1.32 +/- 0.67) at which age the adult pattern in the number of nucleoli was attained. The mean nuclear volume increased steadily from 214.56 +/- 6.48 microns 3 (mean +/- S.E.) at P1 to 326.1 +/- 10.93 microns 3 at P14 where it remained constant. The average cytoplasmic volume underwent a remarkable increase during postnatal period from 256.38 +/- 12.66 microns 3 at P1 to 3791.18 +/- 204.88 microns 3 at P90. It is noteworthy that the stabilization of the number of nucleoli coincides with the termination of the nuclear growth phase of supraoptic neurons. We suggest that these nuclear and nucleolar changes reflect the attainment of the fully-differentiated state of the protein synthesis machinery in these neurosecretory neurons.

  17. Effect of soy milk on circulating 17- β estradiol, number of neurons in cerebral cortex and hippocampus and determination of their ratio in neonatal ovariectomized rats.

    Science.gov (United States)

    Marzban Abbasabadi, Behrokh; Tadjalli, Mina

    2016-01-01

    This study was conducted to evaluate the effect of soy milk on serum 17- β estradiol level and number of neurons in cerebral cortex and hippocampus as well as determination of the ratio of neurons in cortical and hippocampal regions in neonatal ovariectomized rats. Thirty female rats (one day old) were divided into six groups of five. At day 7, ovariectomy surgery was performed in four groups and two other groups were assumed as sham and control groups. Three groups of ovareictomaized rats were fed with soy milk at the doses of 0.75, 1.50 and 3.00 mL kg -1 per day since they were 14. At day 60, the blood samples were collected to measure the17- β estradiol concentration, and then the brain of rats were prepared for histological studies. The serum 17- β estradiol level significantly increased in ovariectomized rats fed with soy milk compared to ovariectomized rats with no soy milk supplementation. In addition, the results showed that soy milk significantly increased the number of neurons in CA1, CA2 and dentate gyrus regions of hippocampus and granular layer of cerebral cortex in ovariectomized rats, whereas there was no significant change in number of neurons in CA3 zone of hippocampus and molecular, pyramidal and multiform layers of cerebral cortex in ovariectomized rats fed with soy milk. The ratio of cerebral cortex neurons to hippocampal neurons had no significant changes among the experimental groups.

  18. Chronic ethanol exposure alters the levels, assembly, and cellular organization of the actin cytoskeleton and microtubules in hippocampal neurons in primary culture.

    Science.gov (United States)

    Romero, Ana M; Esteban-Pretel, Guillermo; Marín, María P; Ponsoda, Xavier; Ballestín, Raúl; Canales, Juan J; Renau-Piqueras, Jaime

    2010-12-01

    The organization and dynamics of microtubules (MTs) and the actin cytoskeleton are critical for the correct development and functions of neurons, including intracellular traffic and signaling. In vitro ethanol exposure impairs endocytosis, exocytosis, and nucleocytoplasmic traffic in astrocytes and alters endocytosis in cultured neurons. In astrocytes, these effects relate to changes in the organization and/or function of MTs and the actin cytoskeleton. To evaluate this possibility in hippocampal cultured neurons, we analyzed if chronic ethanol exposure affects the levels, assembly, and cellular organization of both cytoskeleton elements and the possible underlying mechanisms of these effects by morphological and biochemical methods. In the experiments described below, we provide the first evidence that chronic alcohol exposure decreases the amount of both filamentous actin and polymerized tubulin in neurons and that the number of MTs in dendrites lowers in treated cells. Alcohol also diminishes the MT-associated protein-2 levels, which mainly localizes in the somatodendritic compartment in neurons. Ethanol decreases the levels of total Rac, Cdc42, and RhoA, three small guanosine triphosphatases (GTPases) involved in the organization and dynamics of the actin cytoskeleton and MTs. Yet when alcohol decreases the levels of the active forms (GTP bound) of Rac1 and Cdc42, it does not affect the active form of RhoA. We also investigated the levels of several effector and regulator molecules of these GTPases to find that alcohol induces heterogeneous results. In conclusion, our results show that MT, actin cytoskeleton organization, and Rho GTPase signaling pathways are targets for the toxic effects of ethanol in neurons.

  19. Sleep deprivation causes memory deficits by negatively impacting neuronal connectivity in hippocampal area CA1

    National Research Council Canada - National Science Library

    Havekes, Robbert; Park, Alan J; Tudor, Jennifer C; Luczak, Vincent G; Hansen, Rolf T; Ferri, Sarah L; Bruinenberg, Vibeke M; Poplawski, Shane G; Day, Jonathan P; Aton, Sara J; Radwańska, Kasia; Meerlo, Peter; Houslay, Miles D; Baillie, George S; Abel, Ted

    2016-01-01

    .... Recovery sleep normalizes these structural alterations. Suppression of cofilin function prevents spine loss, deficits in hippocampal synaptic plasticity, and impairments in long-term memory caused by sleep deprivation...

  20. Long-term lithium treatment increases intracellular and extracellular brain-derived neurotrophic factor (BDNF) in cortical and hippocampal neurons at subtherapeutic concentrations.

    Science.gov (United States)

    De-Paula, Vanessa J; Gattaz, Wagner F; Forlenza, Orestes V

    2016-12-01

    The putative neuroprotective effects of lithium treatment rely on the fact that it modulates several homeostatic mechanisms involved in the neurotrophic response, autophagy, oxidative stress, inflammation, and mitochondrial function. Lithium is a well-established therapeutic option for the acute and long-term management of bipolar disorder and major depression. The aim of this study was to evaluate the effects of subtherapeutic and therapeutic concentrations of chronic lithium treatment on brain-derived neurotrophic factor (BDNF) synthesis and secretion. Primary cultures of cortical and hippocampal neurons were treated with different subtherapeutic (0.02 and 0.2 mM) and therapeutic (2 mM) concentrations of chronic lithium treatment in cortical and hippocampal cell culture. Lithium treatment increased the intracellular protein expression of cortical neurons (10% at 0.02 mM) and hippocampal neurons (28% and 14% at 0.02 mM and 0.2 mM, respectively). Extracellular BDNF of cortical neurons increased 30% and 428% at 0.02 and 0.2 mM, respectively and in hippocampal neurons increased 44% at 0.02 mM. The present study indicates that chronic, low-dose lithium treatment up-regulates BDNF production in primary neuronal cell culture. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  1. Wnt Signaling Prevents the Aβ Oligomer-Induced Mitochondrial Permeability Transition Pore Opening Preserving Mitochondrial Structure in Hippocampal Neurons.

    Science.gov (United States)

    Arrázola, Macarena S; Ramos-Fernández, Eva; Cisternas, Pedro; Ordenes, Daniela; Inestrosa, Nibaldo C

    2017-01-01

    Alzheimer's disease (AD) is a neurodegenerative disorder mainly known for synaptic impairment and neuronal cell loss, affecting memory processes. Beside these damages, mitochondria have been implicated in the pathogenesis of AD through the induction of the mitochondrial permeability transition pore (mPTP). The mPTP is a non-selective pore that is formed under apoptotic conditions, disturbing mitochondrial structure and thus, neuronal viability. In AD, Aβ oligomers (Aβos) favor the opening of the pore, activating mitochondria-dependent neuronal cell death cascades. The Wnt signaling activated through the ligand Wnt3a has been described as a neuroprotective signaling pathway against amyloid-β (Aβ) peptide toxicity in AD. However, the mechanisms by which Wnt signaling prevents Aβos-induced neuronal cell death are unclear. We proposed here to study whether Wnt signaling protects neurons earlier than the late damages in the progression of the disease, through the preservation of the mitochondrial structure by the mPTP inhibition. To study specific events related to mitochondrial permeabilization we performed live-cell imaging from primary rat hippocampal neurons, and electron microscopy to analyze the mitochondrial morphology and structure. We report here that Wnt3a prevents an Aβos-induced cascade of mitochondrial events that leads to neuronal cell death. This cascade involves (a) mPTP opening, (b) mitochondrial swelling, (c) mitochondrial membrane potential loss and (d) cytochrome c release, thus leading to neuronal cell death. Furthermore, our results suggest that the activation of the Wnt signaling prevents mPTP opening by two possible mechanisms, which involve the inhibition of mitochondrial GSK-3β and/or the modulation of mitochondrial hexokinase II levels and activity. This study suggests a possible new approach for the treatment of AD from a mitochondrial perspective, and will also open new lines of study in the field of Wnt signaling in neuroprotection.

  2. Astrocyte-Specific Overexpression of Insulin-Like Growth Factor-1 Protects Hippocampal Neurons and Reduces Behavioral Deficits following Traumatic Brain Injury in Mice.

    Directory of Open Access Journals (Sweden)

    Sindhu K Madathil

    Full Text Available Traumatic brain injury (TBI survivors often suffer from long-lasting cognitive impairment that stems from hippocampal injury. Systemic administration of insulin-like growth factor-1 (IGF-1, a polypeptide growth factor known to play vital roles in neuronal survival, has been shown to attenuate posttraumatic cognitive and motor dysfunction. However, its neuroprotective effects in TBI have not been examined. To this end, moderate or severe contusion brain injury was induced in mice with conditional (postnatal overexpression of IGF-1 using the controlled cortical impact (CCI injury model. CCI brain injury produces robust reactive astrocytosis in regions of neuronal damage such as the hippocampus. We exploited this regional astrocytosis by linking expression of hIGF-1 to the astrocyte-specific glial fibrillary acidic protein (GFAP promoter, effectively targeting IGF-1 delivery to vulnerable neurons. Following brain injury, IGF-1Tg mice exhibited a progressive increase in hippocampal IGF-1 levels which was coupled with enhanced hippocampal reactive astrocytosis and significantly greater GFAP levels relative to WT mice. IGF-1 overexpression stimulated Akt phosphorylation and reduced acute (1 and 3d hippocampal neurodegeneration, culminating in greater neuron survival at 10d after CCI injury. Hippocampal neuroprotection achieved by IGF-1 overexpression was accompanied by improved motor and cognitive function in brain-injured mice. These data provide strong support for the therapeutic efficacy of increased brain levels of IGF-1 in the setting of TBI.

  3. Transiently increasing cAMP levels selectively in hippocampal excitatory neurons during sleep deprivation prevents memory deficits caused by sleep loss.

    Science.gov (United States)

    Havekes, Robbert; Bruinenberg, Vibeke M; Tudor, Jennifer C; Ferri, Sarah L; Baumann, Arnd; Meerlo, Peter; Abel, Ted

    2014-11-19

    The hippocampus is particularly sensitive to sleep loss. Although previous work has indicated that sleep deprivation impairs hippocampal cAMP signaling, it remains to be determined whether the cognitive deficits associated with sleep deprivation are caused by attenuated cAMP signaling in the hippocampus. Further, it is unclear which cell types are responsible for the memory impairments associated with sleep deprivation. Transgenic approaches lack the spatial resolution to manipulate specific signaling pathways selectively in the hippocampus, while pharmacological strategies are limited in terms of cell-type specificity. Therefore, we used a pharmacogenetic approach based on a virus-mediated expression of a Gαs-coupled Drosophila octopamine receptor selectively in mouse hippocampal excitatory neurons in vivo. With this approach, a systemic injection with the receptor ligand octopamine leads to increased cAMP levels in this specific set of hippocampal neurons. We assessed whether transiently increasing cAMP levels during sleep deprivation prevents memory consolidation deficits associated with sleep loss in an object-location task. Five hours of total sleep deprivation directly following training impaired the formation of object-location memories. Transiently increasing cAMP levels in hippocampal neurons during the course of sleep deprivation prevented these memory consolidation deficits. These findings demonstrate that attenuated cAMP signaling in hippocampal excitatory neurons is a critical component underlying the memory deficits in hippocampus-dependent learning tasks associated with sleep deprivation. Copyright © 2014 the authors 0270-6474/14/3415715-07$15.00/0.

  4. Brefeldin A-inhibited guanine nucleotide exchange protein 3 is localized in lysosomes and regulates GABA signaling in hippocampal neurons.

    Science.gov (United States)

    Liu, Tao; Li, Hongyu; Hong, Wanjin; Han, Weiping

    2016-12-01

    ADP-ribosylation factor (ARF) family of guanine-nucleotide-binding (G) proteins regulates organelle biogenesis, structure and trafficking. The functions of ARF proteins are tightly controlled by guanine nucleotide exchange factors (GEFs) containing a conserved SEC7 domain. Based on sequence similarity to brefeldin A-inhibited guanine nucleotide exchange protein (BIG)/GBF of the Arf-GEF family, we recently identified BIG3 as a novel ARF GEF protein with a non-functional catalytic motif in the SEC7 domain. BIG3 is mainly expressed in pancreatic islets and brain. In the islets, depletion of BIG3 increases insulin and glucagon secretion because of enhanced biogenesis of insulin and glucagon granules in the absence of BIG3. Here, we investigate BIG3 functions in the brain, in particular its regulation of neurotransmitter release in hippocampal neurons from wild-type and BIG3 knockout mice. In hippocampal neurons, BIG3 is mainly localized in lysosomes, and its depletion selectively impairs inhibitory synaptic transmission. Our finding provides novel insights for a cell-specific function of BIG3 in regulating neurotransmission. © 2016 International Society for Neurochemistry.

  5. Action potential changes associated with impairment of functional properties of sodium channels in hippocampal neurons induced by melamine.

    Science.gov (United States)

    Yang, Jia-Jia; Yang, Zhuo; Zhang, Tao

    2010-10-05

    Since the melamine-contamination event happened in September 2008, there have been lots of studies about melamine toxicity, but very limited studies focused on central nervous system (CNS). In the present study, we investigated the effects of melamine (5x10(-4), 5x10(-5) and 5x10(-6)g/ml) on voltage-gated sodium channels (VGSCs) in hippocampal CA1 neurons using whole-cell patch-clamp recordings technique. The results showed that only 5x10(-4)g/ml melamine reduced the amplitude of voltage-gated sodium current (I(Na)). At the concentrations of 5x10(-5) and 5x10(-4)g/ml, melamine produced a hyperpolarizing shift in the steady-state activation curve of I(Na) and also enhanced the steady-state inactivate processing of I(Na). Action potential properties and the pattern of repetitive firing were examined using current-clamp recording, which indicated that peak amplitude and overshoot of the evoked single action potential were decreased. The half-width and the firing rate of repetitive firing were increased in a concentration-dependent manner. The data suggest that melamine alters the action potential of hippocampal CA1 neurons by impairing the functional properties of VGSCs, which may be the underlie mechanisms of neurotoxicity induced by melamine. Copyright 2010 Elsevier Ireland Ltd. All rights reserved.

  6. ClC-3 Expression and Its Association with Hyperglycemia Induced HT22 Hippocampal Neuronal Cell Apoptosis

    Directory of Open Access Journals (Sweden)

    Feiyan Fan

    2016-01-01

    Full Text Available Although apoptosis plays an important role in the development of Diabetic Encephalopathy (DE, the underlying molecular mechanisms remain unclear. With respect to this, the present work aims to study the variation in chloride/proton exchanger ClC-3 expression and its association with HT22 hippocampal neuronal apoptosis under hyperglycemic condition in vitro. The cells were stimulated with added 0, 5, or 25 mM glucose or mannitol for up to 72 hours before assessing the rate of ClC-3 expression, cell viability, and apoptosis. In a consecutive experiment, cells received chloride channel blocker in addition to glucose. The rate of cellular death/apoptosis and viability was measured using Flow Cytometry and MTT assay, respectively. Changes in ClC-3 expression were assessed using immunofluorescence staining and western blot analysis. The results revealed a significant increase in cellular apoptosis and reduction in viability, associated with increased ClC-3 expression in high glucose group. Osmolarity had no role to play. Addition of chloride channel blocker completely abolished this effect. Thus we conclude that, with its increased expression, ClC-3 plays a major role in hyperglycemia induced hippocampal neuronal apoptosis. To strengthen our understanding of this aforesaid association, we conducted an extensive literature search which is presented in this paper.

  7. Neuroprotective effects of Nigella sativa extract on cell death in hippocampal neurons following experimental global cerebral ischemia-reperfusion injury in rats.

    Science.gov (United States)

    Hobbenaghi, R; Javanbakht, J; Sadeghzadeh, Sh; Kheradmand, D; Abdi, F S; Jaberi, M H; Mohammadiyan, M R; Khadivar, F; Mollaei, Y

    2014-02-15

    Global cerebral ischemia followed by reperfusion, leads to extensive neuronal damage, particularly the neurons in the hippocampal CA region. Recent studies have demonstrated that pharmacological agents, such as Nigella sativa L. (Ranunculaceae) that is an annual herbaceous flowering plant, given at the time of reperfusion afforded protection against ischemia, which is referred to as pharmacological post conditioning. The aim of this study was to evaluate the neuroprotective effects of Nigella sativa in the hippocampus neurons of rats exposed to global ischemia/reperfusion. In the present study 30 Wister rats (200-250 g) were divided into 5 groups namely sham (operated without treatment), control (operation with normal saline treatment), and 3 treatment groups with Nigella sativa 1mg/kg, 10mg/kg and 50mg/kg. Firstly, the animals were anesthetized by ketamin and xylazine, and then the right carotid artery was operated upon dissection of the soft tissues around it and ligation by a clamp for 20 min. The Nigella sativa extraction was used during surgery through IP route and after 72 h the animals were euthanized and their brain removed, fixed and prepared for histopathological examinations. In treatment group (1mg/kg) the interstitial neuron frequency which contains cytoplasmic edema, along with CA, was 28 cells, whereas the edematous astrocyte number along with CA in this group was 115 cells. In the treatment group (10mg/kg) the interstitial neurons of cornua ammonis (CA) were 15 and the edematous astrocytes were 122 cells and in the treatment group (50mg/kg) the number of edematous interstitial neurons was 7 cells in distance of 2900 μ of CA. In such group the number of edematous interstitial neurons was less as well. In this group the appearance of CA cells was more similar to control group, not only the edema decreased in interstitial and astrocyte cells, but it dramatically decreased in pyramidal cells. Our study revealed that the Nigella sativa extraction could

  8. Coexpression of glutamate vesicular transporter (VGLUT1) and choline acetyltransferase (ChAT) proteins in fetal rat hippocampal neurons in culture.

    Science.gov (United States)

    Bhargava, Neelima; Das, Mainak; Edwards, Darin; Stancescu, Maria; Kang, Jung-Fong; Hickman, James J

    2010-09-01

    A very small population of choline acetyltransferase (ChAT) immunoreactive cells is observed in all layers of the adult hippocampus. This is the intrinsic source of the hippocampal cholinergic innervation, in addition to the well-established septo-hippocampal cholinergic projection. This study aimed at quantifying and identifying the origin of this small population of ChAT-immunoreactive cells in the hippocampus at early developmental stages, by culturing the fetal hippocampal neurons in serum-free culture and on a patternable, synthetic silane substrate N-1 [3-(trimethoxysilyl) propyl] diethylenetriamine. Using this method, a large proportion of glutamatergic (glutamate vesicular transporter, VGLUT1-immunoreactive) neurons, a small fraction of GABAergic (GABA-immunoreactive) neurons, and a large proportion of cholinergic (ChAT-immunoreactive) neurons were observed in the culture. Interestingly, most of the glutamatergic neurons that expressed glutamate vesicular transporter (VGLUT1) also co-expressed ChAT proteins. On the contrary, when the cultures were double-stained with GABA and ChAT, colocalization was not observed. Neonatal and adult rat hippocampal neurons were also cultured to verify whether these more mature neurons also co-express VGLUT1 and ChAT proteins in culture. Colocalization of VGLUT1 and ChAT in these relatively more mature neurons was not observed. One possible explanation for this observation is that the neurons have the ability to synthesize multiple neurotransmitters at a very early stage of development and then with time follows a complex, combinatorial strategy of electrochemical coding to determine their final fate.

  9. Inhibition of RhoA GTPase and the subsequent activation of PTP1B protects cultured hippocampal neurons against amyloid β toxicity

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    Rodriguez-Tebar Alfredo

    2011-02-01

    Full Text Available Abstract Background Amyloid beta (Aβ is the main agent responsible for the advent and progression of Alzheimer's disease. This peptide can at least partially antagonize nerve growth factor (NGF signalling in neurons, which may be responsible for some of the effects produced by Aβ. Accordingly, better understanding the NGF signalling pathway may provide clues as to how to protect neurons from the toxic effects of Aβ. Results We show here that Aβ activates the RhoA GTPase by binding to p75NTR, thereby preventing the NGF-induced activation of protein tyrosine phosphatase 1B (PTP1B that is required for neuron survival. We also show that the inactivation of RhoA GTPase and the activation of PTP1B protect cultured hippocampal neurons against the noxious effects of Aβ. Indeed, either pharmacological inhibition of RhoA with C3 ADP ribosyl transferase or the transfection of cultured neurons with a dominant negative form of RhoA protects cultured hippocampal neurons from the effects of Aβ. In addition, over-expression of PTP1B also prevents the deleterious effects of Aβ on cultured hippocampal neurons. Conclusion Our findings indicate that potentiating the activity of NGF at the level of RhoA inactivation and PTP1B activation may represent a new means to combat the noxious effects of Aβ in Alzheimer's disease.

  10. Hippocampal pathology in the human neuronal ceroid-lipofuscinoses: distinct patterns of storage deposition, neurodegeneration and glial activation.

    Science.gov (United States)

    Tyynelä, Jaana; Cooper, Jonathan D; Khan, M Nadeem; Shemilts, Stephen J A; Haltia, Matti

    2004-10-01

    The neuronal ceroid-lipofuscinoses (NCLs) are recessively inherited lysosomal storage diseases, currently classified into 8 forms (CLN1-CLN8). Collectively, the NCLs constitute the most common group of progressive encephalopathies of childhood, and present with visual impairment, psychomotor deterioration and severe seizures. Despite recent identification of the underlying disease genes, the mechanisms leading to neurodegeneration and epilepsy in the NCLs remain poorly understood. To investigate these events, we examined the patterns of storage deposition, neurodegeneration, and glial activation in the hippocampus of patients with CLN1, CLN2, CLN3, CLN5 and CLN8 using histochemistry and immunohistochemistry. These different forms of NCL shared distinct patterns of neuronal degeneration in the hippocampus, with heavy involvement of sectors CA2-CA4 but relative sparing of CA1. This selective pattern of degeneration was also observed in immunohistochemically identified interneurons, which exhibited a graded severity of loss according to phenotype, with calretinin-positive interneurons relatively spared. Furthermore, glial activation was also regionally specific, with microglial activation most pronounced in areas of greatest neuronal loss, and astrocyte activation prominent in areas where neuronal loss was less evident. In conclusion, the NCLs share a common pattern of selective hippocampal pathology, distinct from that seen in the majority of temporal lobe epilepsies.

  11. Effects of low frequency electric fields on synaptic integration in hippocampal CA1 pyramidal neurons: implications for power line emissions

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    Francesco eCavarretta

    2014-10-01

    Full Text Available The possible cognitive effects of low frequency external electric fields, such as those generated by power lines, are poorly understood. Their functional consequences for mechanisms at the single neuron level are very difficult to study and identify experimentally, especially in vivo. The major open problem is that experimental investigations on humans have given inconsistent or contradictory results, making it difficult to estimate the possible effects of external low frequency electric fields on cognitive functions. Here we investigate this issue with a realistic model of hippocampal CA1 pyramidal neurons. The model suggests how and why external electric fields, with environmentally observed frequencies and intensities far lower than what is required for direct neural activation, can perturb dendritic signal processing and somatic firing of neurons that are crucially involved in cognitive tasks such as learning and memory. These results show that individual neuronal morphology, ion channel dendritic distribution, and alignment with the electric field are major determinants of overall effects, and provide a physiologically plausible explanation of why experimental findings can appear to be small and difficult to reproduce, yet deserve serious consideration.

  12. The synergistic effect between β-amyloid(1-42) and α-synuclein on the synapses dysfunction in hippocampal neurons.

    Science.gov (United States)

    Wang, Yixuan; Yu, Zheming; Ren, Huimin; Wang, Jian; Wu, Jianjun; Chen, Yan; Ding, Zhengtong

    2015-01-01

    This study was to explore the molecular mechanisms underpinning the synergetic effect between β-amyloid (Aβ) and α-synuclein (α-syn) on synapses dysfunction during the development of neurodegenerative disorders including Parkinson's disease (PD), dementia with Lewy bodies (DLB) and Alzheimer disease (AD). The primary cultured hippocampal neurons prepared from the fetal tissue of mice were divided into six groups and treated with DMSO, Aβ(42-1), α-syn, Aβ(1-42), α-syn plus Aβ(42-1) and α-syn plus Aβ(1-42), respectively. After incubation for 24 h, the synapsin I content was calculated by immunofluorescence and the synaptic vesicle recycling was monitored by FM1-43 staining. Furthermore, the expression of cysteine string protein-α (CSPα) detected by western blot was also conducted. Either Aβ(1-42) or α-syn alone could induce a significant synapses dysfunction through reducing the content of synapsin I, inhibiting the synaptic vesicle recycling as well as down-regulating the expression of CSPα compared with the controls (P1-42) aggravated these effects in cultured hippocampal neurons compared with the treatment with α-syn (synapsin I content: P1; synaptic vesicle recycling: P=0.007; CSPα expression: P1) or Aβ(1-42) (synapsin I number: P1; synaptic vesicle recycling: P=0.007 CSPα expression: P1) alone. There was synergistic effect between Aβ and α-syn on synapses dysfunction through reducing the synapsin I content, inhibiting the synaptic vesicle recycling and down-regulating the expression of CSPα in several neurodegenerative diseases. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Repositioning of Somatic Golgi Apparatus Is Essential for the Dendritic Establishment of Adult-Born Hippocampal Neurons.

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    Rao, Sneha; Kirschen, Gregory W; Szczurkowska, Joanna; Di Antonio, Adrian; Wang, Jia; Ge, Shaoyu; Shelly, Maya

    2018-01-17

    New dentate granule cells (DGCs) are continuously generated, and integrate into the preexisting hippocampal network in the adult brain. How an adult-born neuron with initially simple spindle-like morphology develops into a DGC, consisting of a single apical dendrite with further branches, remains largely unknown. Here, using retroviruses to birth date and manipulate newborn neurons, we examined initial dendritic formation and possible underlying mechanisms. We found that GFP-expressing newborn cells began to establish a DGC-like morphology at ∼7 d after birth, with a primary dendrite pointing to the molecular layer, but at this stage, with several neurites in the neurogenic zone. Interestingly, the Golgi apparatus, an essential organelle for neurite growth and maintenance, was dynamically repositioning in the soma of newborn cells during this initial integration stage. Two weeks after birth, by which time most neurites in the neurogenic zone were eliminated, a compact Golgi apparatus was positioned exclusively at the base of the primary dendrite. We analyzed the presence of Golgi-associated genes using single-cell transcriptomes of newborn DGCs, and among Golgi-related genes, found the presence of STK25 and STRAD , regulators of embryonic neuronal development. When we knocked down either of these two proteins, we found Golgi mislocalization and extensive aberrant dendrite formation. Furthermore, overexpression of a mutated form of STRAD, underlying the disorder polyhydramnios, megalencephaly, and symptomatic epilepsy, characterized by abnormal brain development and intractable epilepsy, caused similar defects in Golgi localization and dendrite formation in adult-born neurons. Together, our findings reveal a role for Golgi repositioning in regulating the initial integration of adult-born DGCs. SIGNIFICANCE STATEMENT Since the discovery of the continuous generation of new neurons in the adult hippocampus, extensive effort was directed toward understanding the

  14. When Are New Hippocampal Neurons, Born in the Adult Brain, Integrated into the Network That Processes Spatial Information?

    Science.gov (United States)

    Sandoval, C. Jimena; Pérez, Oswaldo; Ramírez-Amaya, Víctor

    2011-01-01

    Adult-born neurons in the dentate gyrus (DG) functionally integrate into the behaviorally relevant hippocampal networks, showing a specific Arc-expression response to spatial exploration when mature. However, it is not clear when, during the 4- to 6-week interval that is critical for survival and maturation of these neurons, this specific response develops. Therefore, we characterized Arc expression after spatial exploration or cage control conditions in adult-born neurons from rats that were injected with BrdU on one day and were sacrificed 1, 7, 15, 30, and 45 days post-BrdU injection (PBI). Triple immunostaining for NeuN, Arc, and BrdU was analyzed through the different DG layers. Arc protein expression in BrdU-positive cells was observed from day 1 to day 15 PBI but was not related to behavioral stimulation. The specific Arc-expression response to spatial exploration was observed from day 30 and 45 in about 5% of the BrdU-positive cell population. Most of the BrdU-positive neurons expressing Arc in response to spatial exploration (∼90%) were located in DG layer 1, and no Arc expression was observed in cells located in the subgranular zone (SGZ). Using the current data and that obtained previously, we propose a mathematical model suggesting that new neurons are unlikely to respond to exploration by expressing Arc after they are 301 days old, and also that in a 7-month-old rat the majority (60%) of the neurons that respond to exploration must have been born during adulthood; thus, suggesting that adult neurogenesis in the DG is highly relevant for spatial information processing. PMID:21408012

  15. Zolpidem reduces hippocampal neuronal activity in freely behaving mice: a large scale calcium imaging study with miniaturized fluorescence microscope.

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    Tamara Berdyyeva

    Full Text Available Therapeutic drugs for cognitive and psychiatric disorders are often characterized by their molecular mechanism of action. Here we demonstrate a new approach to elucidate drug action on large-scale neuronal activity by tracking somatic calcium dynamics in hundreds of CA1 hippocampal neurons of pharmacologically manipulated behaving mice. We used an adeno-associated viral vector to express the calcium sensor GCaMP3 in CA1 pyramidal cells under control of the CaMKII promoter and a miniaturized microscope to observe cellular dynamics. We visualized these dynamics with and without a systemic administration of Zolpidem, a GABAA agonist that is the most commonly prescribed drug for the treatment of insomnia in the United States. Despite growing concerns about the potential adverse effects of Zolpidem on memory and cognition, it remained unclear whether Zolpidem alters neuronal activity in the hippocampus, a brain area critical for cognition and memory. Zolpidem, when delivered at a dose known to induce and prolong sleep, strongly suppressed CA1 calcium signaling. The rate of calcium transients after Zolpidem administration was significantly lower compared to vehicle treatment. To factor out the contribution of changes in locomotor or physiological conditions following Zolpidem treatment, we compared the cellular activity across comparable epochs matched by locomotor and physiological assessments. This analysis revealed significantly depressive effects of Zolpidem regardless of the animal's state. Individual hippocampal CA1 pyramidal cells differed in their responses to Zolpidem with the majority (∼ 65% significantly decreasing the rate of calcium transients, and a small subset (3% showing an unexpected and significant increase. By linking molecular mechanisms with the dynamics of neural circuitry and behavioral states, this approach has the potential to contribute substantially to the development of new therapeutics for the treatment of CNS disorders.

  16. Zolpidem reduces hippocampal neuronal activity in freely behaving mice: a large scale calcium imaging study with miniaturized fluorescence microscope.

    Science.gov (United States)

    Berdyyeva, Tamara; Otte, Stephani; Aluisio, Leah; Ziv, Yaniv; Burns, Laurie D; Dugovic, Christine; Yun, Sujin; Ghosh, Kunal K; Schnitzer, Mark J; Lovenberg, Timothy; Bonaventure, Pascal

    2014-01-01

    Therapeutic drugs for cognitive and psychiatric disorders are often characterized by their molecular mechanism of action. Here we demonstrate a new approach to elucidate drug action on large-scale neuronal activity by tracking somatic calcium dynamics in hundreds of CA1 hippocampal neurons of pharmacologically manipulated behaving mice. We used an adeno-associated viral vector to express the calcium sensor GCaMP3 in CA1 pyramidal cells under control of the CaMKII promoter and a miniaturized microscope to observe cellular dynamics. We visualized these dynamics with and without a systemic administration of Zolpidem, a GABAA agonist that is the most commonly prescribed drug for the treatment of insomnia in the United States. Despite growing concerns about the potential adverse effects of Zolpidem on memory and cognition, it remained unclear whether Zolpidem alters neuronal activity in the hippocampus, a brain area critical for cognition and memory. Zolpidem, when delivered at a dose known to induce and prolong sleep, strongly suppressed CA1 calcium signaling. The rate of calcium transients after Zolpidem administration was significantly lower compared to vehicle treatment. To factor out the contribution of changes in locomotor or physiological conditions following Zolpidem treatment, we compared the cellular activity across comparable epochs matched by locomotor and physiological assessments. This analysis revealed significantly depressive effects of Zolpidem regardless of the animal's state. Individual hippocampal CA1 pyramidal cells differed in their responses to Zolpidem with the majority (∼ 65%) significantly decreasing the rate of calcium transients, and a small subset (3%) showing an unexpected and significant increase. By linking molecular mechanisms with the dynamics of neural circuitry and behavioral states, this approach has the potential to contribute substantially to the development of new therapeutics for the treatment of CNS disorders.

  17. Sigma-1 receptor agonist increases axon outgrowth of hippocampal neurons via voltage-gated calcium ions channels.

    Science.gov (United States)

    Li, Dong; Zhang, Shu-Zhuo; Yao, Yu-Hong; Xiang, Yun; Ma, Xiao-Yun; Wei, Xiao-Li; Yan, Hai-Tao; Liu, Xiao-Yan

    2017-12-01

    Sigma-1 receptors (Sig-1Rs) are unique endoplasmic reticulum proteins that have been implicated in both neurodegenerative and ischemic diseases, such as Alzheimer's disease and stroke. Accumulating evidence has suggested that Sig-1R plays a role in neuroprotection and axon outgrowth. The underlying mechanisms of Sig-1R-mediated neuroprotection have been well elucidated. However, the mechanisms underlying the effects of Sig-1R on axon outgrowth are not fully understood. To clarify this issue, we utilized immunofluorescence to compare the axon lengths of cultured naïve hippocampal neurons before and after the application of the Sig-1R agonist, SA4503. Then, electrophysiology and immunofluorescence were used to examine voltage-gated calcium ion channel (VGCCs) currents in the cell membranes and growth cones. We found that Sig-1R activation dramatically enhanced the axonal length of the naïve hippocampal neurons. Application of the Sig-1R antagonist NE100 and gene knockdown techniques both demonstrated the effects of Sig-1R. The growth-promoting effect of SA4503 was accompanied by the inhibition of voltage-gated Ca2+ influx and was recapitulated by incubating the neurons with the L-type, N-type, and P/Q-type VGCC blockers, nimodipine, MVIIA and ω-agatoxin IVA, respectively. This effect was unrelated to glial cells. The application of SA4503 transformed the growth cone morphologies from complicated to simple, which favored axon outgrowth. Sig-1R activation can enhance axon outgrowth and may have a substantial influence on neurogenesis and neurodegenerative diseases. © 2017 John Wiley & Sons Ltd.

  18. Transient receptor potential vanilloid 4 inhibits γ-aminobutyric acid-activated current in hippocampal pyramidal neurons

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    Zhiwen Hong

    2016-08-01

    Full Text Available The balance between excitatory and inhibitory neurotransmitter systems is crucial for the modulation of neuronal excitability in the central nervous system. The activation of transient receptor potential vanilloid 4 (TRPV4 is reported to enhance the response of hippocampal glutamate receptors, but whether the inhibitory neurotransmitter system can be regulated by TRPV4 remains unknown. γ-aminobutyric acid (GABA is the major inhibitory neurotransmitter in the central nervous system. Here, we show that application of transient receptor potential vanilloid 4 (TRPV4 synthetic (GSK1016790A or 4-PDD or endogenous agonist (5,6-EET inhibited GABA-activated current (IGABA in hippocampal CA1 pyramidal neurons, which was blocked by specific antagonists of TRPV4 and of GABAA receptors. GSK1016790A increased the phosphorylated AMP-activated protein kinase (p-AMPK and decreased the phosphorylated protein kinase B (p-Akt protein levels, which was attenuated by removing extracellular calcium or by a calcium/calmodulin-dependent protein kinase kinase-β antagonist. GSK1016790A-induced decrease of p-Akt protein level was sensitive to an AMPK antagonist. GSK1016790A-inhibited IGABA was blocked by an AMPK antagonist or a phosphatidyl inositol 3 kinase (PI3K agonist. GSK1016790A-induced inhibition of IGABA was also significantly attenuated by a protein kinase C (PKC antagonist but was unaffected by protein kinase A or calcium/calmodulin-dependent protein kinase II antagonist. We conclude that activation of TRPV4 inhibits GABAA receptor, which may be mediated by activation of AMPK and subsequent down-regulation of PI3K/Akt signaling and activation of PKC signaling. Inhibition of GABAA receptors may account for the neuronal hyperexcitability caused by TRPV4 activation.

  19. Ablation of sphingosine 1-phosphate receptor subtype 3 impairs hippocampal neuron excitability in vitro and spatial working memory in vivo

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    Daniela Weth-Malsch

    2016-11-01

    Full Text Available Understanding the role of the bioactive lipid mediator sphingosine 1-phosphate (S1P within the central nervous system has recently gained more and more attention, as it has been connected to major diseases such as multiple sclerosis and Alzheimer's disease. Even though much data about the functions of the five S1P receptors has been collected for other organ systems, we still lack a complete understanding for their specific roles, in particular within the brain. Therefore, it was the aim of this study to further elucidate the role of S1P receptor subtype 3 (S1P3 in vivo and in vitro with a special focus on the hippocampus. Using an S1P3 knock-out mouse model we applied a range of behavioral tests, performed expression studies and whole cell patch clamp recordings in acute hippocampal slices. We were able to show that S1P3 deficient mice display a significant spatial working memory deficit within the T-maze test, but not in anxiety related tests. Furthermore, S1p3 mRNA was expressed throughout the hippocampal formation. Principal neurons in area CA3 lacking S1P3 showed significantly increased interspike intervals and a significantly decreased input resistance. Upon stimulation with S1P CA3 principal neurons from both wildtype and S1P3-/- mice displayed significantly increased evoked EPSC amplitudes and decay times, whereas rise times remained unchanged. These results suggest a specific involvement of S1P3 for the establishment of spatial working memory and neuronal excitability within the hippocampus.

  20. δ-Catenin Regulates Spine and Synapse Morphogenesis and Function in Hippocampal Neurons during Development

    Science.gov (United States)

    Arikkath, Jyothi; Peng, I-Feng; Ng, Yu Gie; Israely, Inbal; Liu, Xin; Ullian, Erik M.; Reichardt, Louis F.

    2009-01-01

    The maintenance of spine and synapse number during development is critical for neuronal circuit formation and function. Here we show that δ-catenin, a component of the cadherin-catenin cell adhesion complex, regulates spine and synapse morphogenesis during development. Genetic ablation or acute knockdown of δ-catenin leads to increases in spine and synapse density, accompanied by a decrease in tetrodotoxin induced spine plasticity. Our results indicate that δ-catenin may mediate conversion of activity-dependent signals to morphological spine plasticity. The functional role of δ-catenin in regulating spine density does not require binding to cadherins, but does require interactions with PDZ domain-containing proteins. We propose that the perturbations in spine and synaptic structure and function observed after depletion of δ-catenin during development may contribute to functional alterations in neural circuitry, the cognitive deficits observed in mutant mice, and the mental retardation pathology of Cri-du-chat syndrome. PMID:19403811

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

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    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.

  2. Single-molecule imaging of Nav1.6 on the somatic surface of hippocampal neurons reveals unique nanoclusters

    CERN Document Server

    Akin, Elizabeth J; Johnson, Ben; Beheiry, Mohamed el; Masson, Jean-Baptiste; Krapf, Diego; Tamkun, Michael M

    2016-01-01

    Voltage-gated sodium (Na$_v$) channels are responsible for the depolarizing phase of the action potential in most nerve cells and Na$_v$ channel localization to the axon initial segment is vital to action potential initiation. Na$_v$ channels in the soma play a role in the transfer of axonal output information to the rest of the neuron and in synaptic plasticity, although little is known about Na$_v$ channel localization and dynamics within this neuronal compartment. The present study uses single-particle tracking and photoactivation localization microscopy to analyze cell-surface Na$_v$1.6 within the soma of cultured hippocampal neurons. Mean square displacement analysis of individual trajectories indicated half of the somatic Na$_v$1.6 channels localized to stable nanoclusters ~230 nm in diameter. Strikingly, these domains were stabilized at specific sites on the cell membrane for greater than 30 min, notably via an ankyrin-independent mechanism, indicating the mechanism by which Na$_v$1.6 nanoclusters are ...

  3. AMPA receptor pHluorin-GluA2 reports NMDA receptor-induced intracellular acidification in hippocampal neurons

    DEFF Research Database (Denmark)

    Rathje, Mette; Fang, Huaqiang; Bachman, Julia L

    2013-01-01

    NMDA receptor activation promotes endocytosis of AMPA receptors, which is an important mechanism underlying long-term synaptic depression. The pH-sensitive GFP variant pHluorin fused to the N terminus of GluA2 (pH-GluA2) has been used to assay NMDA-mediated AMPA receptor endocytosis and recycling....... Here, we demonstrate that in somatic and dendritic regions of hippocampal neurons a large fraction of the fluorescent signal originates from intracellular pH-GluA2, and that the decline in fluorescence in response to NMDA and AMPA primarily describes an intracellular acidification, which quenches the p......Hluorin signal from intracellular receptor pools. Neurons expressing an endoplasmic reticulum-retained mutant of GluA2 (pH-GluA2 ΔC49) displayed a larger response to NMDA than neurons expressing wild-type pH-GluA2. A similar NMDA-elicited decline in pHluorin signal was observed by expressing cytosolic p...

  4. Altered Chloride Homeostasis Decreases the Action Potential Threshold and Increases Hyperexcitability in Hippocampal Neurons.

    Science.gov (United States)

    Sørensen, Andreas T; Ledri, Marco; Melis, Miriam; Nikitidou Ledri, Litsa; Andersson, My; Kokaia, Merab

    2017-01-01

    Chloride ions play an important role in controlling excitability of principal neurons in the central nervous system. When neurotransmitter GABA is released from inhibitory interneurons, activated GABA type A (GABA A ) receptors on principal neurons become permeable to chloride. Typically, chloride flows through activated GABA A receptors into the neurons causing hyperpolarization or shunting inhibition, and in turn inhibits action potential (AP) generation. However, in situations when intracellular chloride concentration is increased, chloride ions can flow in opposite direction, depolarize neurons, and promote AP generation. It is generally recognized that altered chloride homeostasis per se has no effect on the AP threshold. Here, we demonstrate that chloride overload of mouse principal CA3 pyramidal neurons not only makes these cells more excitable through GABA A receptor activation but also lowers the AP threshold, further aggravating excitability. This phenomenon has not been described in principal neurons and adds to our understanding of mechanisms regulating neuronal and network excitability, particularly in developing brain and during pathological situations with altered chloride homeostasis. This finding further broadens the spectrum of neuronal plasticity regulated by ionic compositions across the cellular membrane.

  5. Excitotoxic insult results in a long-lasting activation of CaMKIIα and mitochondrial damage in living hippocampal neurons.

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    Nikolai Otmakhov

    Full Text Available Over-activation of excitatory NMDA receptors and the resulting Ca2+ overload is the main cause of neuronal toxicity during stroke. CaMKII becomes misregulated during such events. Biochemical studies show either a dramatic loss of CaMKII activity or its persistent autonomous activation after stroke, with both of these processes being implicated in cell toxicity. To complement the biochemical data, we monitored CaMKII activation in living hippocampal neurons in slice cultures using high spatial/temporal resolution two-photon imaging of the CaMKIIα FRET sensor, Camui. CaMKII activation state was estimated by measuring Camui fluorescence lifetime. Short NMDA insult resulted in Camui activation followed by a redistribution of its protein localization: an increase in spines, a decrease in dendritic shafts, and concentration into numerous clusters in the cell soma. Camui activation was either persistent (> 1-3 hours or transient (~20 min and, in general, correlated with its protein redistribution. After longer NMDA insult, however, Camui redistribution persisted longer than its activation, suggesting distinct regulation/phases of these processes. Mutational and pharmacological analysis suggested that persistent Camui activation was due to prolonged Ca2+ elevation, with little impact of autonomous states produced by T286 autophosphorylation and/or by C280/M281 oxidation. Cell injury was monitored using expressible mitochondrial marker mito-dsRed. Shortly after Camui activation and clustering, NMDA treatment resulted in mitochondrial swelling, with persistence of the swelling temporarily linked to the persistence of Camui activation. The results suggest that in living neurons excitotoxic insult produces long-lasting Ca2+-dependent active state of CaMKII temporarily linked to cell injury. CaMKII function, however, is to be restricted due to strong clustering. The study provides the first characterization of CaMKII activation dynamics in living neurons

  6. Working memory performance correlates with prefrontal-hippocampal theta interactions but not with prefrontal neuron firing rates

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    James M Hyman

    2010-03-01

    Full Text Available Performance of memory tasks is impaired by lesions to either the medial prefrontal cortex (mPFC or the hippocampus (HPC; although how these two areas contribute to successful performance is not well understood. mPFC unit activity is temporally affected by hippocampal theta oscillations, with almost half the mPFC population entrained to theta in behaving animals, pointing to theta interactions as the mechanism enabling collaborations between these two areas. mPFC neurons respond to sensory stimuli and responses in working memory tasks, though the function of these correlated firing rate changes remains unclear because similar responses are reported during mPFC dependent and independent tasks. Using a DNMS task we compared error trials vs. correct trials and found almost all mPFC cells fired at similar rates during both error and correct trials (92%, however theta-entrainment of mPFC neurons declined during error performance as only 17% of cells were theta-entrained (during correct trials 46% of the population was theta-entrained. Across the population, error and correct trials did not differ in firing rate, but theta-entrainment was impaired. Periods of theta-entrainment and firing rate changes appeared to be independent variables, and only theta-entrainment was correlated with successful performance, indicating mPFC-HPC theta range interactions are the key to successful DNMS performance.

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

    Science.gov (United States)

    Lau, Chi-Fai; Ho, Yuen-Shan; Hung, Clara Hiu-Ling; Poon, Chun-Hei; Chiu, Kin; Yang, Xifei

    2014-01-01

    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. PMID:25045655

  8. 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.

  9. Neuroprotective Effects of Inhibiting Fyn S-Nitrosylation on Cerebral Ischemia/Reperfusion-Induced Damage to CA1 Hippocampal Neurons

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    Lingyun Hao

    2016-07-01

    Full Text Available Nitric oxide (NO can regulate signaling pathways via S-nitrosylation. Fyn can be post-translationally modified in many biological processes. In the present study, using a rat four-vessel-occlusion ischemic model, we aimed to assess whether Fyn could be S-nitrosylated and to evaluate the effects of Fyn S-nitrosylation on brain damage. In vitro, Fyn could be S-nitrosylated by S-nitrosoglutathione (GSNO, an exogenous NO donor, and in vivo, endogenous NO synthesized by NO synthases (NOS could enhance Fyn S-nitrosylation. Application of GSNO, 7-nitroindazole (7-NI, an inhibitor of neuronal NOS and hydrogen maleate (MK-801, the N-methyl-d-aspartate receptor (NMDAR antagonist could decrease the S-nitrosylation and phosphorylation of Fyn induced by cerebral ischemia/reperfusion (I/R. Cresyl violet staining validated that these compounds exerted neuroprotective effects against the cerebral I/R-induced damage to hippocampal CA1 neurons. Taken together, in this study, we demonstrated that Fyn can be S-nitrosylated both in vitro and in vivo and that inhibiting S-nitrosylation can exert neuroprotective effects against cerebral I/R injury, potentially via NMDAR-mediated mechanisms. These findings may lead to a new field of inquiry to investigate the underlying pathogenesis of stroke and the development of novel treatment strategies.

  10. Rutin upregulates neurotrophic factors resulting in attenuation of ethanol-induced oxidative stress in HT22 hippocampal neuronal cells.

    Science.gov (United States)

    Song, Kibbeum; Na, Ji-Young; Kim, Sokho; Kwon, Jungkee

    2015-08-15

    Alcoholism, which refers to the excessive consumption of alcohol, has deleterious effects on personal and social health worldwide. Oxidative stress evoked by ethanol plays an important role in the pathogenesis of neurodegenerative diseases. Rutin is a bioflavonoid that has been demonstrated to scavenge superoxide radicals. However, the effects of rutin on neuronal toxicity following ethanol-induced oxidative stress have not previously been investigated. Thus we investigated the antioxidant effect of rutin in hippocampal neuronal cells (HT22 cells) exposed to ethanol. We found that rutin pretreatment prevented the ethanol-induced decrease in protein level expression of nerve growth factor, glial cell line-derived neurotrophic factor (GDNF) and brain-derived neurotrophic factor (BDNF) in HT22 cells. Cell viability as analyzed by the MTT method revealed a significant increase in cell viability in the rutin-treated group compared with the ethanol-only treated group. Antioxidant effect of rutin was confirmed to be due to reduction of intracellular reactive oxidative species production in ethanol-treated HT22 cells. Moreover, rutin significantly increased the level of the antioxidant glutathione, and the activities of the antioxidant enzymes superoxide dismutase and catalase. These findings indicate that rutin has potential as a therapeutic agent to treat alcohol-related neurodegenerative disorders. © 2014 Society of Chemical Industry.

  11. Visualization of spatiotemporal energy dynamics of hippocampal neurons by mass spectrometry during a kainate-induced seizure.

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    Yuki Sugiura

    Full Text Available We report the use of matrix-assisted laser desorption/ionization (MALDI imaging mass spectrometry combined with capillary electrophoresis (CE mass spectrometry to visualize energy metabolism in the mouse hippocampus by imaging energy-related metabolites. We show the distribution patterns of ATP, ADP, and AMP in the hippocampus as well as changes in their amounts and distribution patterns in a murine model of limbic, kainate-induced seizure. As an acute response to kainate administration, we found massive and moderate reductions in ATP and ADP levels, respectively, but no significant changes in AMP levels--especially in cells of the CA3 layer. The results suggest the existence of CA3 neuron-selective energy metabolism at the anhydride bonds of ATP and ADP in the hippocampal neurons during seizure. In addition, metabolome analysis of energy synthesis pathways indicates accelerated glycolysis and possibly TCA cycle activity during seizure, presumably due to the depletion of ATP. Consistent with this result, the observed energy depletion significantly recovered up to 180 min after kainate administration. However, the recovery rate was remarkably low in part of the data-pixel population in the CA3 cell layer region, which likely reflects acute and CA3-selective neural death. Taken together, the present approach successfully revealed the spatiotemporal energy metabolism of the mouse hippocampus at a cellular resolution--both quantitatively and qualitatively. We aim to further elucidate various metabolic processes in the neural system.

  12. Tissue-based metabolic labeling of polysialic acids in living primary hippocampal neurons

    National Research Council Canada - National Science Library

    Kyungtae Kang; Sunghoon Joo; Ji Yu Choi; Sujeong Geum; Seok-Pyo Hong; Seung-Yeul Lee; Yong Ho Kim; Seong-Min Kim; Myung-Han Yoon; Yoonkey Nam; Kyung-Bok Lee; Hee-Yoon Lee; Insung S. Choi

    2015-01-01

    ... to present N-azidoacetyl sialic acid to PSA-NCAM. Although significant neurotoxicity was observed in the conventional metabolic labeling that used the dissociated neuron cells, neurotoxicity disappeared in this modified strategy, allowing...

  13. Altered Chloride Homeostasis Decreases the Action Potential Threshold and Increases Hyperexcitability in Hippocampal Neurons

    DEFF Research Database (Denmark)

    Sørensen, Andreas T; Ledri, Marco; Melis, Miriam

    2017-01-01

    flows through activated GABAA receptors into the neurons causing hyperpolarization or shunting inhibition, and in turn inhibits action potential (AP) generation. However, in situations when intracellular chloride concentration is increased, chloride ions can flow in opposite direction, depolarize...

  14. Sleep deprivation and hippocampal vulnerability : Changes in neuronal plasticity, neurogenesis and cognitive function

    NARCIS (Netherlands)

    Kreutzmann, J C; Havekes, R; Abel, T; Meerlo, P

    2015-01-01

    Despite the ongoing fundamental controversy about the physiological function of sleep, there is general consensus that sleep benefits neuronal plasticity, which ultimately supports brain function and cognition. In agreement with this are numerous studies showing that sleep deprivation (SD) results

  15. Receptor protein tyrosine phosphatase alpha is essential for hippocampal neuronal migration and long-term potentiation

    DEFF Research Database (Denmark)

    Petrone, Angiola; Battaglia, Fortunato; Wang, Cheng

    2003-01-01

    Despite clear indications of their importance in lower organisms, the contributions of protein tyrosine phosphatases (PTPs) to development or function of the mammalian nervous system have been poorly explored. In vitro studies have indicated that receptor protein tyrosine phosphatase alpha (RPTPa....... However, these synapses are unable to undergo long-term potentiation. Mice lacking RPTPalpha also underperform in the radial-arm water-maze test. These studies identify RPTPalpha as a key mediator of neuronal migration and synaptic plasticity....... neuronal migration. The migratory abnormality likely results from a radial glial dysfunction rather than from a neuron-autonomous defect. In spite of this aberrant development, basic synaptic transmission from the Schaffer collateral pathway to CA1 pyramidal neurons remains intact in Ptpra(-/-) mice...

  16. Oxytocin stimulates hippocampal neurogenesis via oxytocin receptor expressed in CA3 pyramidal neurons.

    Science.gov (United States)

    Lin, Yu-Ting; Chen, Chien-Chung; Huang, Chiung-Chun; Nishimori, Katsuhiko; Hsu, Kuei-Sen

    2017-09-14

    In addition to the regulation of social and emotional behaviors, the hypothalamic neuropeptide oxytocin has been shown to stimulate neurogenesis in adult dentate gyrus; however, the mechanisms underlying the action of oxytocin are still unclear. Taking advantage of the conditional knockout mouse model, we show here that endogenous oxytocin signaling functions in a non-cell autonomous manner to regulate survival and maturation of newly generated dentate granule cells in adult mouse hippocampus via oxytocin receptors expressed in CA3 pyramidal neurons. Through bidirectional chemogenetic manipulations, we also uncover a significant role for CA3 pyramidal neuron activity in regulating adult neurogenesis in the dentate gyrus. Retrograde neuronal tracing combined with immunocytochemistry revealed that the oxytocin neurons in the paraventricular nucleus project directly to the CA3 region of the hippocampus. Our findings reveal a critical role for oxytocin signaling in adult neurogenesis.Oxytocin (OXT) has been implicated in adult neurogenesis. Here the authors show that CA3 pyramidal cells in the adult mouse hippocampus express OXT receptors and receive inputs from hypothalamic OXT neurons; activation of OXT signaling in CA3 pyramidal cells promotes the survival and maturation of newborn neurons in the dentate gyrus in a non-cell autonomous manner.

  17. Network bursting using experimentally constrained single compartment CA3 hippocampal neuron models with adaptation.

    Science.gov (United States)

    Dur-e-Ahmad, Muhammad; Nicola, Wilten; Campbell, Sue Ann; Skinner, Frances K

    2012-08-01

    The hippocampus is a brain structure critical for memory functioning. Its network dynamics include several patterns such as sharp waves that are generated in the CA3 region. To understand how population outputs are generated, models need to consider aspects of network size, cellular and synaptic characteristics and context, which are necessarily 'balanced' in appropriate ways to produce particular outputs. Thick slice hippocampal preparations spontaneously produce sharp waves that are initiated in CA3 regions and depend on the right balance of glutamatergic activities. As a step toward developing network models that can explain important balances in the generation of hippocampal output, we develop models of CA3 pyramidal cells. Our models are single compartment in nature, use an Izhikevich-type structure and involve parameter values that are specifically designed to encompass CA3 intrinsic properties. Importantly, they incorporate spike frequency adaptation characteristics that are directly comparable to those measured experimentally. Excitatory networks using these model cells are able to produce bursting suggesting that the amount of spike frequency adaptation expressed in the biological cells is an essential contributor to network bursting, and as such, may be important for sharp wave generation. The network bursting mechanism is numerically dissected showing the critical balance between adaptation and excitatory drive. The compact nature of our models allows large network simulations to be efficiently computed. This, together with the linkage of our models to cellular characteristics, will allow us to develop an understanding of population output of CA3 hippocampus with direct biological comparisons.

  18. Neuronal Splicing Regulator RBFOX3 (NeuN Regulates Adult Hippocampal Neurogenesis and Synaptogenesis.

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    Yi-Sian Lin

    Full Text Available Dysfunction of RBFOX3 has been identified in neurodevelopmental disorders such as autism spectrum disorder, cognitive impairments and epilepsy and a causal relationship with these diseases has been previously demonstrated with Rbfox3 homozygous knockout mice. Despite the importance of RBFOX3 during neurodevelopment, the function of RBFOX3 regarding neurogenesis and synaptogenesis remains unclear. To address this critical question, we profiled the developmental expression pattern of Rbfox3 in the brain of wild-type mice and analyzed brain volume, disease-relevant behaviors, neurogenesis, synaptic plasticity, and synaptogenesis in Rbfox3 homozygous knockout mice and their corresponding wild-type counterparts. Here we report that expression of Rbfox3 differs developmentally for distinct brain regions. Moreover, Rbfox3 homozygous knockout mice exhibited cold hyperalgesia and impaired cognitive abilities. Focusing on hippocampal phenotypes, we found Rbfox3 homozygous knockout mice displayed deficits in neurogenesis, which was correlated with cognitive impairments. Furthermore, RBFOX3 regulates the exons of genes with synapse-related function. Synaptic plasticity and density, which are related to cognitive behaviors, were altered in the hippocampal dentate gyrus of Rbfox3 homozygous knockout mice; synaptic plasticity decreased and the density of synapses increased. Taken together, our results demonstrate the important role of RBFOX3 during neural development and maturation. In addition, abnormalities in synaptic structure and function occur in Rbfox3 homozygous knockout mice. Our findings may offer mechanistic explanations for human brain diseases associated with dysfunctional RBFOX3.

  19. High Content Analysis of Hippocampal Neuron-Astrocyte Co-cultures Shows a Positive Effect of Fortasyn Connect on Neuronal Survival and Postsynaptic Maturation

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    Anne-Lieke F. van Deijk

    2017-08-01

    Full Text Available Neuronal and synaptic membranes are composed of a phospholipid bilayer. Supplementation with dietary precursors for phospholipid synthesis –docosahexaenoic acid (DHA, uridine and choline– has been shown to increase neurite outgrowth and synaptogenesis both in vivo and in vitro. A role for multi-nutrient intervention with specific precursors and cofactors has recently emerged in early Alzheimer's disease, which is characterized by decreased synapse numbers in the hippocampus. Moreover, the medical food Souvenaid, containing the specific nutrient combination Fortasyn Connect (FC, improves memory performance in early Alzheimer's disease patients, possibly via maintaining brain connectivity. This suggests an effect of FC on synapses, but the underlying cellular mechanism is not fully understood. Therefore, we investigated the effect of FC (consisting of DHA, eicosapentaenoic acid (EPA, uridine, choline, phospholipids, folic acid, vitamins B12, B6, C and E, and selenium, on synaptogenesis by supplementing it to primary neuron-astrocyte co-cultures, a cellular model that mimics metabolic dependencies in the brain. We measured neuronal developmental processes using high content screening in an automated manner, including neuronal survival, neurite morphology, as well as the formation and maturation of synapses. Here, we show that FC supplementation resulted in increased numbers of neurons without affecting astrocyte number. Furthermore, FC increased postsynaptic PSD95 levels in both immature and mature synapses. These findings suggest that supplementation with FC to neuron-astrocyte co-cultures increased both neuronal survival and the maturation of postsynaptic terminals, which might aid the functional interpretation of FC-based intervention strategies in neurological diseases characterized by neuronal loss and impaired synaptic functioning.

  20. The organizational and aromatization hypotheses apply to rapid, nonclassical hormone action: neonatal masculinization eliminates rapid estradiol action in female hippocampal neurons.

    Science.gov (United States)

    Meitzen, John; Grove, Danielle D; Mermelstein, Paul G

    2012-10-01

    Early exposure to the steroid sex hormone testosterone and its estrogen metabolite estradiol masculinize neural tissue during a developmental critical period. Many aspects of neuron anatomy and physiology are permanently altered, including later sensitivity to estradiol. Although it is well established that early hormone exposure alters neuronal responsiveness regarding classical estradiol actions (i.e. acting via nuclear estrogen receptors), it has not yet been determined whether it also alters neuronal processing of nonclassical estrogen receptor signaling, including the actions of membrane-associated estrogen receptors. Hence, we tested whether membrane estrogen receptor regulation of cAMP response element binding protein (CREB) phosphorylation observed in female (but not male) hippocampal pyramidal neurons is due to the lack of androgen and/or estrogen exposure in females during this critical period. Female rat neonates on postnatal d 0 and 1 were systemically injected with one of four compounds: vehicle, testosterone, the nonaromatizable androgen dihydrotestosterone, or estradiol. On postnatal d 2, primary hippocampal neuron cultures were generated from these animals. After 8-9 d in culture, we assessed whether estradiol affected CREB phosphorylation. Neurons from female neonates exposed to testosterone lacked estradiol signaling to CREB. In contrast, dihydrotestosterone injections of female neonates did not disrupt estradiol regulation of CREB. Estradiol injections of female neonates, however, eliminated estradiol signaling to CREB. These findings indicate that testosterone aromatization to estradiol leads to a masculinization/defeminization process whereby hippocampal neurons fail to exhibit rapid estradiol signaling to CREB. Broadly, these findings extend the organizational and aromatization hypotheses to rapid, nonclassical hormone action.

  1. Sialidase NEU4 hydrolyzes polysialic acids of neural cell adhesion molecules and negatively regulates neurite formation by hippocampal neurons.

    Science.gov (United States)

    Takahashi, Kohta; Mitoma, Junya; Hosono, Masahiro; Shiozaki, Kazuhiro; Sato, Chihiro; Yamaguchi, Kazunori; Kitajima, Ken; Higashi, Hideyoshi; Nitta, Kazuo; Shima, Hiroshi; Miyagi, Taeko

    2012-04-27

    Modulation of levels of polysialic acid (polySia), a sialic acid polymer, predominantly associated with the neural cell adhesion molecule (NCAM), influences neural functions, including synaptic plasticity, neurite growth, and cell migration. Biosynthesis of polySia depends on two polysialyltransferases ST8SiaII and ST8SiaIV in vertebrate. However, the enzyme involved in degradation of polySia in its physiological turnover remains uncertain. In the present study, we identified and characterized a murine sialidase NEU4 that catalytically degrades polySia. Murine NEU4, dominantly expressed in the brain, was found to efficiently hydrolyze oligoSia and polySia chains as substrates in sialidase in vitro assays, and also NCAM-Fc chimera as well as endogenous NCAM in tissue homogenates of postnatal mouse brain as assessed by immunoblotting with anti-polySia antibodies. Degradation of polySia by NEU4 was also evident in neuroblastoma Neuro2a cells that were co-transfected with Neu4 and ST8SiaIV genes. Furthermore, in mouse embryonic hippocampal primary neurons, the endogenously expressed NEU4 was found to decrease during the neuronal differentiation. Interestingly, GFP- or FLAG-tagged NEU4 was partially co-localized with polySia in neurites and significantly suppressed their outgrowth, whereas silencing of NEU4 showed the acceleration together with an increase in polySia expression. These results suggest that NEU4 is involved in regulation of neuronal function by polySia degradation in mammals.

  2. Intracellular calcium level is an important factor influencing ion channel modulations by PLC-coupled metabotropic receptors in hippocampal neurons.

    Science.gov (United States)

    Sugawara, Yuto; Echigo, Ryousuke; Kashima, Kousuke; Minami, Hanae; Watanabe, Megumi; Nishikawa, Yuiko; Muranishi, Miho; Yoneda, Mitsugu; Ohno-Shosaku, Takako

    2013-05-28

    Signaling pathways involving phospholipase C (PLC) are involved in various neural functions. Understanding how these pathways are regulated will lead to a better understanding of their roles in neural functions. Previous studies demonstrated that receptor-driven PLCβ activation depends on intracellular Ca(2+) concentration ([Ca(2+)]i), suggesting the possibility that PLCβ-dependent cellular responses are basically Ca(2+) dependent. To test this possibility, we examined whether modulations of ion channels driven by PLC-coupled metabotropic receptors are sensitive to [Ca(2+)]i using cultured hippocampal neurons. Muscarinic activation triggered an inward current at -100 mV (the equilibrium potential for K(+)) in a subpopulation of neurons. This current response was suppressed by pirenzepine (an M1-preferring antagonist), PLC inhibitor, non-selective cation channel blocker, and lowering [Ca(2+)]i. Using the neurons showing no response at -100 mV, effects of muscarinic activation on K(+) channels were examined at -40 mV. Muscarinic activation induced a transient decrease of the holding outward current. This current response was mimicked and occluded by XE991, an M-current K(+) channel blocker, suppressed by pirenzepine, PLC inhibitor and lowering [Ca(2+)]i, and enhanced by elevating [Ca(2+)]i. Similar results were obtained when group I metabotropic glutamate receptors were activated instead of muscarinic receptors. These results clearly show that ion channel modulations driven by PLC-coupled metabotropic receptors are dependent on [Ca(2+)]i, supporting the hypothesis that cellular responses induced by receptor-driven PLCβ activation are basically Ca(2+) dependent. Copyright © 2013 Elsevier B.V. All rights reserved.

  3. Effects of fructose-1,6-bisphosphate on morphological and functional neuronal integrity in rat hippocampal slices during energy deprivation.

    Science.gov (United States)

    Izumi, Y; Benz, A M; Katsuki, H; Matsukawa, M; Clifford, D B; Zorumski, C F

    2003-01-01

    D-fructose-1,6-bisphosphate, a high energy glycolytic intermediate, attenuates ischemic damage in a variety of tissues, including brain. To determine whether D-fructose-1,6-bisphosphate serves as an alternate energy substrate in the CNS, rat hippocampal slices were treated with D-fructose-1,6-bisphosphate during glucose deprivation. Unlike pyruvate, an endproduct of glycolysis, 10 mM D-fructose-1,6-bisphosphate did not preserve synaptic transmission or morphological integrity of CA1 pyramidal neurons during glucose deprivation. Moreover, during glucose deprivation, 10-mM D-fructose-1,6-bisphosphate failed to maintain adenosine triphosphate levels in slices. D-fructose-1,6-bisphosphate, however, attenuated acute neuronal degeneration produced by 200 microM iodoacetate, an inhibitor of glycolysis downstream of D-fructose-1,6-bisphosphate. Because (5S, 10R)-(+)-5-methyl-10, 11-dihydro-5H-dibenzo [a,d]cyclohepten-5,10-imine, an antagonist of N-methyl-D-aspartate receptors, exhibited similar protection against iodoacetate damage, we examined whether (5S, 10R)-(+)-5-methyl-10, 11-dihydro-5H-dibenzo [a,d]cyclohepten-5,10-imine and D-fructose-1,6-bisphosphate share a common neuroprotective mechanism. Indeed, D-fructose-1,6-bisphosphate diminished N-methyl-D-aspartate receptor-mediated synaptic responses and partially attenuated neuronal degeneration induced by 100-microM N-methyl-D-aspartate. Taken together, these results indicate that D-fructose-1,6-bisphosphate is unlikely to serve as an energy substrate in the hippocampus, and that neuroprotective effects of D-fructose-1,6-bisphosphate are mediated by mechanisms other than anaerobic energy supply. Copyright 2003 IBRO

  4. Kainic acid (KA)-induced Ca2+/calmodulin-dependent protein kinase II (CaMK II) expression in the neurons, astrocytes and microglia of the mouse hippocampal CA3 region, and the phosphorylated CaMK II only in the hippocampal neurons.

    Science.gov (United States)

    Suh, Hong-Won; Lee, Han-Kyu; Seo, Young-Jun; Kwon, Min-Soo; Shim, Eon-Jeong; Lee, Jin-Young; Choi, Seong-Soo; Lee, Jong-Ho

    2005-06-24

    In the present study, we investigated the role of Ca2+/calmodulin-dependent protein kinase II (CaMK II) and which types of neuronal cells contain CaMK II and phosphorylated CaMK II (p-CaMK II) in the CA3 hippocampal region of mice using confocal immunofluorescence study. KA increased the CaMK II, p-CaMK II, glial fibrillary acidic protein (GFAP) and complement receptor type 3 (OX-42) immunoreactivities (IR) at 30 min after KA treatment in mouse hippocampal area. In studies, nevertheless KA-induced CaMK II is expressed in neurons or astrocytes or microglia, p-CaMK II is expressed only in neurons. Thus, our results suggest that the activated CaMK II in early time may be performed important roles only in neurons but not in the astrocytes and microglia.

  5. 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

    2010-11-01

    Full Text Available 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.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 entire pyramidal neuron and occasionally

  6. Scanning Ultrasound (SUS Causes No Changes to Neuronal Excitability and Prevents Age-Related Reductions in Hippocampal CA1 Dendritic Structure in Wild-Type Mice.

    Directory of Open Access Journals (Sweden)

    Robert John Hatch

    Full Text Available Scanning ultrasound (SUS is a noninvasive approach that has recently been shown to ameliorate histopathological changes and restore memory functions in an Alzheimer's disease mouse model. Although no overt neuronal damage was reported, the short- and long-term effects of SUS on neuronal excitability and dendritic tree morphology had not been investigated. To address this, we performed patch-clamp recordings from hippocampal CA1 pyramidal neurons in wild-type mice 2 and 24 hours after a single SUS treatment, and one week and 3 months after six weekly SUS treatments, including sham treatments as controls. In both treatment regimes, no changes in CA1 neuronal excitability were observed in SUS-treated neurons when compared to sham-treated neurons at any time-point. For the multiple treatment groups, we also determined the dendritic morphology and spine densities of the neurons from which we had recorded. The apical trees of sham-treated neurons were reduced at the 3 month time-point when compared to one week; however, surprisingly, no longitudinal change was detected in the apical dendritic trees of SUS-treated neurons. In contrast, the length and complexity of the basal dendritic trees were not affected by SUS treatment at either time-point. The apical dendritic spine densities were reduced, independent of the treatment group, at 3 months compared to one week. Collectively, these data suggest that ultrasound can be employed to prevent an age-associated loss of dendritic structure without impairing neuronal excitability.

  7. Reduced Hyperpolarization-Activated Current Contributes to Enhanced Intrinsic Excitability in Cultured Neonatal Hippocampal Neurons from PrP−/− Mice

    Directory of Open Access Journals (Sweden)

    Jing eFan

    2016-03-01

    Full Text Available Genetic ablation of cellular prion protein (PrPC 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 PrPC 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 PrPC. The amplitude of voltage sag, a characteristic of activating HCN channel current (Ih, was decreased in null mice. Moreover, Ih 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 PrPC. 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.

  8. Neuroprotective Effect of Uncaria rhynchophylla in Kainic Acid-Induced Epileptic Seizures by Modulating Hippocampal Mossy Fiber Sprouting, Neuron Survival, Astrocyte Proliferation, and S100B Expression

    Directory of Open Access Journals (Sweden)

    Chung-Hsiang Liu

    2012-01-01

    Full Text Available Uncaria rhynchophylla (UR, which is a traditional Chinese medicine, has anticonvulsive effect in our previous studies, and the cellular mechanisms behind this are still little known. Because of this, we wanted to determine the importance of the role of UR on kainic acid- (KA- induced epilepsy. Oral UR for 6 weeks can successfully attenuate the onset of epileptic seizure in animal tests. Hippocampal mossy fiber sprouting dramatically decreased, while neuronal survival increased with UR treatment in hippocampal CA1 and CA3 areas. Furthermore, oral UR for 6 weeks significantly attenuated the overexpression of astrocyte proliferation and S100B proteins but not γ-aminobutyric acid A (GABAA receptors. These results indicate that oral UR for 6 weeks can successfully attenuate mossy fiber sprouting, astrocyte proliferation, and S100B protein overexpression and increase neuronal survival in KA-induced epileptic rat hippocampus

  9. Changes in the Golgi apparatus of neocortical and hippocampal neurons in the hibernating hamster

    Directory of Open Access Journals (Sweden)

    Alejandro eAntón

    2015-12-01

    Full Text Available Hibernating animals have been used as models to study several aspects of the plastic changes that occur in the metabolism and physiology of neurons. These models are also of interest in the study of Alzheimer’s disease because the microtubule-associated protein tau is hyperphosphorylated during the hibernation state known as torpor, similar to the pretangle stage of Alzheimer’s disease. Hibernating animals undergo torpor periods with drops in body temperature and metabolic rate, and a virtual cessation of neural activity. These processes are accompanied by morphological and neurochemical changes in neurons, which reverse a few hours after coming out of the torpor state. Since tau has been implicated in the structural regulation of the neuronal Golgi apparatus (GA we have used Western Blot and immunocytochemistry to analyze whether the GA is modified in cortical neurons of the Syrian hamster at different hibernation stages. The results show that, during the hibernation cycle, the GA undergo important structural changes along with differential modifications in expression levels and distribution patterns of Golgi structural proteins. These changes were accompanied by significant transitory reductions in the volume and surface area of the GA elements during torpor and arousal stages as compared with euthermic animals

  10. Ultrastructural analysis of the functional domains in FMRP using primary hippocampal mouse neurons

    NARCIS (Netherlands)

    G.J. Levenga (Josien); R.A.M. Buijsen (Ronald); M. Rifé (Maria); H. Moine (Hervé); D.L. Nelson (David); B.A. Oostra (Ben); R. Willemsen (Rob); F.M.S. Vrij (Femke)

    2009-01-01

    textabstractFragile X syndrome is caused by lack of the protein FMRP. FMRP mediates mRNA binding, dendritic mRNA transport and translational control at spines. We examined the role of functional domains of FMRP in neuronal RNA-granule formation and dendritic transport using different FMRP variants,

  11. Escitalopram attenuates ?-amyloid-induced tau hyperphosphorylation in primary hippocampal neurons through the 5-HT1A receptor mediated Akt/GSK-3? pathway

    OpenAIRE

    Wang, Yan-Juan; Ren, Qing-Guo; Gong, Wei-Gang; Wu, Di; Tang, Xiang; Li, Xiao-Li; Wu, Fang-Fang; Bai, Feng; Xu, Lin; Zhang, Zhi-Jun

    2016-01-01

    Tau hyperphosphorylation is an important pathological feature of Alzheimer's disease (AD). To investigate whether escitalopram could inhibit amyloid-? (A?)-induced tau hyperphosphorylation and the underlying mechanisms, we treated the rat primary hippocampal neurons with A?1-42 and examined the effect of escitalopram on tau hyperphosphorylation. Results showed that escitalopram decreased A?1?42-induced tau hyperphosphorylation. In addition, escitalopram activated the Akt/GSK-3? pathway, and t...

  12. A STEREOLOGICAL ANALYSIS OF THE EFFECT OF EARLY POSTNATAL ETHANOL EXPOSURE ON NEURONAL NUMBERS IN RAT DENTATE GYRUS

    Directory of Open Access Journals (Sweden)

    Takanori Miki

    2011-05-01

    Full Text Available Maternal ethanol ingestion during pregnancy can cause fetal alcohol syndrome (FAS in their offspring. Among the symptoms of FAS, damage to the central nervous system has emerged as one of the most serious problems. We have previously shown that a relatively high dose of ethanol exposure during early postnatal life can cause alterations in spatial learning ability. This ability is controlled, at least in part, by the hippocampal formation. The purpose of the present study was to determine whether exposure of rat pups to ethanol during early postnatal life had effects on the total number of the dentate gyrus neurons. Wistar rats were exposed to a relatively high daily dose of ethanol between postnatal days 10 to 15. Ethanol exposure was achieved by placing rat pups in a chamber containing ethanol vapour for 3 hours a day. The blood ethanol concentration was found to be about 430 mg/dL at the end of the exposure period. Groups of ethanol treated (ET, separation controls (SC and mother reared controls (MRC were anaesthetised and killed at 16-days-of-age by perfusion with phosphate-buffered 2.5% glutaraldehyde. The Cavalieri principle was used to determine the volume of subdivisions of the dentate gyrus, and the physical disector method was used to estimate the numerical densities of neurons within each subdivision. The total number of neurons was calculated by multiplying estimates of the numerical density with the volume. There was, on average, about 421,000 granule cells in all three treatment groups. In the hilus region, ET rats had about 27,000 neuronal cells. This value was significantly smaller than the average of 38,000 such neurons estimated to be present in both MRC and SC animals. It is concluded that neurons in the hilus region of the dentate gyrus may be particularly vulnerable to the effects of a high dose of ethanol exposure during PND 10-15. It is likely that this deficit was due to neuronal death induced by some mechanisms related to

  13. A selective histone deacetylase-6 inhibitor improves BDNF trafficking in hippocampal neurons from Mecp2 knockout mice:implications for Rett syndrome

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    Xin eXu

    2014-03-01

    Full Text Available Rett syndrome (RTT is a neurodevelopmental disorder caused by loss-of-function mutations in the transcriptional modulator methyl-CpG-binding protein 2 (MECP2. One of the most prominent gene targets of MeCP2 is brain-derived neurotrophic factor (Bdnf, a potent modulator of activity-dependent synaptic development, function and plasticity. Dysfunctional BDNF signaling has been demonstrated in several pathophysiological mechanisms of RTT disease progression. To evaluate whether the dynamics of BDNF trafficking is affected by Mecp2 deletion, we analyzed movements of BDNF tagged with yellow fluorescent protein (YFP in cultured hippocampal neurons by time-lapse fluorescence imaging. We found that both anterograde and retrograde vesicular trafficking of BDNF-YFP are significantly impaired in Mecp2 knockout hippocampal neurons. Selective inhibitors of histone deacetylase 6 (HDAC6 show neuroprotective effects in neurodegenerative diseases and stimulate microtubule-dependent vesicular trafficking of BDNF-containing dense core vesicles. Here, we show that the selective HDAC6 inhibitor Tubastatin-A increased the velocity of BDNF-YFP vesicles in Mecp2 knockout neurons in both directions by increasing αtubulin acetylation. Tubastatin-A also restored activity-dependent BDNF release from Mecp2 knockout neurons to levels comparable to those shown by wildtype neurons. These findings demonstrate that a selective HDAC6 inhibitor is a potential pharmacological strategy to reverse cellular and synaptic impairments in RTT resulting from impaired BDNF signaling.

  14. Slow fluctuations of single unit activities of hippocampal and thalamic neurons in cats. I. Relation to natural sleep and alert states.

    Science.gov (United States)

    Kodama, T; Mushiake, H; Shima, K; Nakahama, H; Yamamoto, M

    1989-05-15

    Spontaneous unit discharges during the natural sleep-wakefulness cycle in two different neuronal groups, the hippocampal pyramidal cells and thalamic ventrobasal neurons, have been analyzed. The results show that both neurons fire with white-noise-like fluctuations during the slow-wave sleep, and with slow fluctuations with power spectral densities inversely proportional to the frequency in the frequency range of 0.02-1.0 Hz, during the paradoxical sleep. This confirms that the characteristics of fluctuations in neuronal activities of the mesencephalic reticular formation observed in our previous study are more general phenomena in the cat's brain. Partly similar behavior of spectral densities is also observed during the alert state. These observations are quantitatively confirmed by the statistical time series analysis of the spike density processes of spontaneous activities.

  15. Long-Term Stimulation with Electroacupuncture at DU20 and ST36 Rescues Hippocampal Neuron through Attenuating Cerebral Blood Flow in Spontaneously Hypertensive Rats

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    Gui-Hua Tian

    2013-01-01

    Full Text Available This study was designed to investigate the effect of long-term electroacupuncture at Baihui (DU20 and Zusanli (ST36 on cerebral microvessels and neurons in CA1 region of hippocampus in spontaneously hypertensive rats (SHR. A total of 45 male Wistar rats and 45 SHR were randomly grouped, with or without electroacupuncture (EA at DU20 and ST36, once every other day for a period of 8 weeks. The mean arterial pressure (MAP was measured once every 2 weeks. Cerebral blood flow (CBF and the number of open microvessels in hippocampal CA1 region were detected by Laser Doppler and immunohistochemistry, respectively. Nissl staining and Western blotting were performed, respectively, to determine hippocampus morphology and proteins that were implicated in the concerning signaling pathways. The results showed that the MAP in SHR increased linearly over the observation period and was significantly reduced following electroacupuncture as compared with sham control SHR rats, while no difference was observed in Wistar rats between EA and sham control. The CBF, learning and memory capacity, and capillary rarefaction of SHR were improved by EA. The upregulation of angiotensin II type I receptor (AT1R, endothelin receptor (ETAR, and endothelin-1 (ET-1 in SHR rats was attenuated by electroacupuncture, suggesting an implication of AT1R, ETAR, and ET-1 pathway in the effect of EA.

  16. Stress, hippocampal neurogenesis and cognition: functional correlations

    NARCIS (Netherlands)

    Lucassen, P.J.; Oomen, C.A.

    2016-01-01

    The brain of many species including humans, harbors stem cells that continue to generate new neurons up into adulthood. This form of structural plasticity occurs in a limited number of brain regions, i.e. the subventricular zone and the hippocampal dentate gyrus and is regulated by environmental and

  17. α2-Adrenergic Receptor and Isoflurane Modulation of Presynaptic Ca2+ Influx and Exocytosis in Hippocampal Neurons.

    Science.gov (United States)

    Hara, Masato; Zhou, Zhen-Yu; Hemmings, Hugh C

    2016-09-01

    Evidence indicates that the anesthetic-sparing effects of α2-adrenergic receptor (AR) agonists involve α2A-AR heteroreceptors on nonadrenergic neurons. Since volatile anesthetics inhibit neurotransmitter release by reducing synaptic vesicle (SV) exocytosis, the authors hypothesized that α2-AR agonists inhibit nonadrenergic SV exocytosis and thereby potentiate presynaptic inhibition of exocytosis by isoflurane. Quantitative imaging of fluorescent biosensors of action potential-evoked SV exocytosis (synaptophysin-pHluorin) and Ca influx (GCaMP6) were used to characterize presynaptic actions of the clinically used α2-AR agonists dexmedetomidine and clonidine, and their interaction with isoflurane, in cultured rat hippocampal neurons. Dexmedetomidine (0.1 μM, n = 10) or clonidine (0.5 μM, n = 8) inhibited action potential-evoked exocytosis (54 ± 5% and 59 ± 8% of control, respectively; P exocytosis were blocked by the subtype-nonselective α2-AR antagonist atipamezole or the α2A-AR-selective antagonist BRL 44408 but not by the α2C-AR-selective antagonist JP 1302. Dexmedetomidine inhibited exocytosis and presynaptic Ca influx without affecting Ca coupling to exocytosis, consistent with an effect upstream of Ca-exocytosis coupling. Exocytosis coupled to both N-type and P/Q-type Ca channels was inhibited by dexmedetomidine or clonidine. Dexmedetomidine potentiated inhibition of exocytosis by 0.7 mM isoflurane (to 42 ± 5%, compared to 63 ± 8% for isoflurane alone; P exocytosis is inhibited by α2A-AR activation in proportion to reduced Ca entry. These effects are additive with those of isoflurane, consistent with a role for α2A-AR presynaptic heteroreceptor inhibition of nonadrenergic synaptic transmission in the anesthetic-sparing effects of α2A-AR agonists.

  18. On the number of preganglionic neurones driving human postganglionic sympathetic neurones: a comparison of modelling and empirical data

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    Vaughan G Macefield

    2011-12-01

    Full Text Available Postganglionic sympathetic axons in awake healthy human subjects, regardless of their identity as muscle vasoconstrictor, cutaneous vasoconstrictor or sudomotor neurones, discharge with a low firing probability (~30%, generate low firing rates (~0.5 Hz and typically fire only once per cardiac interval. The purpose of the present study was to use modelling of spike trains in an attempt to define the number of preganglionic neurones that drive an individual postganglionic neurone. Artificial spike trains were generated in 1-3 preganglionic neurones converging onto a single postganglionic neurone. Each preganglionic input fired with a mean interval distribution of either 1000, 1500, 2000, 2500 or 3000 ms and the standard deviation varied between 0.5, 1.0 and 2.0 x the mean interval; the discharge frequency of each preganglionic neurone exhibited positive skewness and kurtosis. Of the 45 patterns examined, the mean discharge properties of the postganglionic neurone could only be explained by it being driven by, on average, two preganglionic neurones firing with a mean interspike interval of 2500 ms and SD of 5000 ms. The mean firing rate resulting from this pattern was 0.22 Hz, comparable to that of spontaneously active muscle vasoconstrictor neurones in healthy subjects (0.40 Hz. Likewise, the distribution of the number of spikes per cardiac interval was similar between the modelled and actual data: 0 spikes (69.5 vs 66.6 %, 1 spike (25.6 vs 21.2 %, 2 spikes (4.3 vs 6.4 %, 3 spikes (0.5 vs 1.7 % and 4 spikes (0.1 vs 0.7 %. Although some features of the firing patterns could be explained by the postganglionic neurone being driven by a single preganglionic neurone, none of the emulated firing patterns generated by the firing of three preganglionic neurones matched the discharge of the real neurones. These modelling data indicate that, on average, human postganglionic sympathetic neurones are driven by two preganglionic inputs.

  19. Recruitment of resting vesicles into recycling pools supports NMDA receptor-dependent synaptic potentiation in cultured hippocampal neurons

    Science.gov (United States)

    Ratnayaka, Arjuna; Marra, Vincenzo; Bush, Daniel; Burden, Jemima J; Branco, Tiago; Staras, Kevin

    2012-01-01

    Most presynaptic terminals in the central nervous system are characterized by two functionally distinct vesicle populations: a recycling pool, which supports action potential-driven neurotransmitter release via vesicle exocytosis, and a resting pool. The relative proportions of these two pools are highly variable between individual synapses, prompting speculation on their specific relationship, and on the possible functions of the resting pool. Using fluorescence imaging of FM-styryl dyes and synaptophysinI-pHluorin (sypHy) as well as correlative electron microscopy approaches, we show here that Hebbian plasticity-dependent changes in synaptic strength in rat hippocampal neurons can increase the recycling pool fraction at the expense of the resting pool in individual synaptic terminals. This recruitment process depends on NMDA-receptor activation, nitric oxide signalling and calcineurin and is accompanied by an increase in the probability of neurotransmitter release at individual terminals. Blockade of actin-mediated intersynaptic vesicle exchange does not prevent recycling pool expansion demonstrating that vesicle recruitment is intrasynaptic. We propose that the conversion of resting pool vesicles to the functionally recycling pool provides a rapid mechanism to implement long-lasting changes in presynaptic efficacy. PMID:22271866

  20. The depolarizing action of GABA in cultured hippocampal neurons is not due to the absence of ketone bodies.

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    Jaylyn Waddell

    Full Text Available Two recent reports propose that the depolarizing action of GABA in the immature brain is an artifact of in vitro preparations in which glucose is the only energy source. The authors argue that this does not mimic the physiological environment because the suckling rats use ketone bodies and pyruvate as major sources of metabolic energy. Here, we show that availability of physiologically relevant levels of ketone bodies has no impact on the excitatory action of GABA in immature cultured hippocampal neurons. Addition of β-hydroxybutyrate (BHB, the primary ketone body in the neonate rat, affected neither intracellular calcium elevation nor membrane depolarizations induced by the GABA-A receptor agonist muscimol, when assessed with calcium imaging or perforated patch-clamp recording, respectively. These results confirm that the addition of ketone bodies to the extracellular environment to mimic conditions in the neonatal brain does not reverse the chloride gradient and therefore render GABA hyperpolarizing. Our data are consistent with the existence of a genuine "developmental switch" mechanism in which GABA goes from having a predominantly excitatory role in immature cells to a predominantly inhibitory one in adults.

  1. Selenium suppresses glutamate-induced cell death and prevents mitochondrial morphological dynamic alterations in hippocampal HT22 neuronal cells.

    Science.gov (United States)

    Ma, Yan-Mei; Ibeanu, Gordon; Wang, Li-Yao; Zhang, Jian-Zhong; Chang, Yue; Dong, Jian-Da; Li, P Andy; Jing, Li

    2017-01-19

    Previous studies have indicated that selenium supplementation may be beneficial in neuroprotection against glutamate-induced cell damage, in which mitochondrial dysfunction is considered a major pathogenic feature. However, the exact mechanisms by which selenium protects against glutamate-provoked mitochondrial perturbation remain ambiguous. In this study glutamate exposed murine hippocampal neuronal HT22 cell was used as a model to investigate the underlying mechanisms of selenium-dependent protection against mitochondria damage. We find that glutamate-induced cytotoxicity was associated with enhancement of superoxide production, activation of caspase-9 and -3, increases of mitochondrial fission marker and mitochondrial morphological changes. Selenium significantly resolved the glutamate-induced mitochondria structural damage, alleviated oxidative stress, decreased Apaf-1, caspases-9 and -3 contents, and altered the autophagy process as observed by a decline in the ratio of the autophagy markers LC3-I and LC3-II. These findings suggest that the protection of selenium against glutamate stimulated cell damage of HT22 cells is associated with amelioration of mitochondrial dynamic imbalance.

  2. Rosmarinic acid protects rat hippocampal neurons from cerebral ischemia/reperfusion injury via the Akt/JNK3/caspase-3 signaling pathway.

    Science.gov (United States)

    Zhang, Min; Yan, Hui; Li, Sumei; Yang, Jun

    2017-02-15

    Cerebral ischemia/reperfusion injury can result in neuronal death, which further results in brain damage and can even lead to death. Although recent studies showed that rosmarinic acid (RA) exerts neuroprotective effects and attenuates ischemia-induced brain injury and neuronal cell death, little is known about the precise mechanisms that occur during cerebral ischemia/reperfusion (I/R). Therefore, the aim of this study was to examine the underlying mechanism of the neuroprotective effects of RA against ischemic brain injury induced by cerebral I/R. Transient global brain ischemia was induced by 4-vessel occlusion in adult male Sprague-Dawley rats. We randomly divided rats into five groups: sham, I/R, I/R+RA, I/R+Vehicle and I/R+RA+LY. Open-field, closed-field and Morris water maze tests were carried our separately to examine the anxiety and cognitive behavior of each group. Cresyl violet staining was used to examine the survival of hippocampal CA1 pyramidal neurons. The levels of p-Akt, p-JNK3 and cleaved caspase-3 in the hippocampus were also examined by Western blotting. Our results showed that administration of RA protected locomotive ability, relieved anxiety behavior and protected cognitive ability in cerebral I/R-injured rats. Additionally, RA significantly protected neurons in the hippocampal CA1 region against cerebral I/R-induced damage. Furthermore, RA increased the phosphorylation of Akt1, downregulated the phosphorylation of JNK3 and reduced the expression of cleaved caspase-3. Finally, the Akt inhibitor LY294002 reversed all the protective effects of RA, indicating that RA protects neurons in the hippocampal CA1 region from ischemic damage through the Akt/JNK3/caspase-3 signaling pathway. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Protective effects of plant seed extracts against amyloid β-induced neurotoxicity in cultured hippocampal neurons

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    Yoshinori Okada

    2013-01-01

    Full Text Available Aim: Alzheimer′s disease (AD is characterized by large deposits of amyloid β (Aβ peptide. Aβ is known to increase reactive oxygen species (ROS production in neurons, leading to cell death. In this study, we screened 15 plant seeds′ aqueous extracts (PSAE for inhibitory effects on Aβ (25-35-induced cell death using hippocampus neurons (HIPN. Materials and Methods: Fifteen chosen plants were nine medical herbs (Japanese honeywort, luffa, rapeseed, Chinese colza, potherb mustard, Japanese radish, bitter melon, red shiso, corn, and kaiware radish and six general commercial plants (common bean, komatsuna, Qing geng cai, bell pepper, kale, and lettuce. PSAE were measured for total phenolic content (TPC with the Folin-Ciocalteu method, and the 2-diphenyl-1-picryl-hydrazyl (DPPH radical scavenging effect of each seed extract was measured. To find a protectant against Aβ-induced oxidative stress, we screened 15 PSAE using a 2′, 7′-dichlorofluorescein diacetate assay. To further unravel the anti-inflammatory effects of PSAE on Aβ-induced inflammation, PSAE were added to HIPN. The neuroprotective effects of the PSAE were evaluated by Cell Counting Kit-8 assay, measuring the cell viability in Aβ-induced HIPN. Results: TPC of 15 PSAE was in the range of 0.024-1.96 mg of chlorogenic acid equivalents/gram. The aqueous extracts showed antioxidant activities. Furthermore, intracellular ROS accumulation resulting from Aβ treatment was reduced when cells were treated with some PSAE. Kale, bitter melon, kaiware radish, red shiso, and corn inhibited tumor necrosis factor-alpha secretion by the Aβ-stimulated neurons and all samples except Japanese honeywort showed enhancement of cell survival. Conclusion: From these results, we suggest that some plant seed extracts offer protection against Aβ-mediated cell death.

  4. Persistent slow inward calcium current in voltage-clamped hippocampal neurones of the guinea-pig.

    Science.gov (United States)

    Brown, D A; Griffith, W H

    1983-04-01

    CA1 and CA3 neurones in transverse slices of guinea-pig hippocampus were voltage clamped through a single micro-electrode, and perfused with Krebs solution containing 0.5 microM-tetrodotoxin and 10 mM-tetraethylammonium at (normally) 24-26 degrees C. Slow inward currents of less than or equal to 0.5 nA were recorded during depolarizing voltage commands to membrane potentials positive to between -40 and -30 mV. These currents peaked at 100-300 msec after the onset of the depolarizing command, then subsequently declined during continuing depolarization. This decline could be ascribed to a developing outward current since repolarizing inward current tails showed no diminution up to 700 msec. No clear evidence for time-dependent inactivation of the inward current could be obtained. A persistent component of inward current could be detected when the membrane potential was maintained above the inward current threshold, such that small hyperpolarizing commands induced an outward relaxation and large hyperpolarizations produced an inward tail current. The inward current was depressed by removing external Ca, or by adding 0.2-0.5 mM-Cd, or 0.1 mM-verapamil, and was increased by adding 1 mM-Ba. A possible role for this persistent inward current in generating the slow membrane depolarization underlying burst discharges in these neurones is discussed. In some neurones (primarily CA1), an additional fast spike-like current was recorded, which was blocked by Cd or Mn and depressed by a depolarizing pre-pulse. It is suggested that this was a manifestation of the previously-reported dendritic Ca spike.

  5. SMAD pathway mediation of BDNF and TGFβ2 regulation of proliferation and differentiation of hippocampal granule neurons

    OpenAIRE

    Lu, J.; Wu, Y.; Sousa, Nuno; Almeida, O F X

    2005-01-01

    Hippocampal granule cells self-renew throughout life, whereas their cerebellar counterparts become post-mitotic during early postnatal development, suggesting that locally acting, tissue-specific factors may regulate the proliferative potential of each cell type. Confirming this, we show that conditioned medium from hippocampal cells (CMHippocampus) stimulates proliferation in cerebellar cultures and, vice versa, that mitosis in hippocampal cells is inhibited by CMCere...

  6. Sirt6 alters adult hippocampal neurogenesis.

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    Eitan Okun

    Full Text Available Sirtuins are pleiotropic NAD+ dependent histone deacetylases involved in metabolism, DNA damage repair, inflammation and stress resistance. SIRT6, a member of the sirtuin family, regulates the process of normal aging and increases the lifespan of male mice over-expressing Sirt6 by 15%. Neurogenesis, the formation of new neurons within the hippocampus of adult mammals, involves several complex stages including stem cell proliferation, differentiation, migration and network integration. During aging, the number of newly generated neurons continuously declines, and this is correlated with a decline in neuronal plasticity and cognitive behavior. In this study we investigated the involvement of SIRT6 in adult hippocampal neurogenesis. Mice over-expressing Sirt6 exhibit increased numbers of young neurons and decreased numbers of mature neurons, without affecting glial differentiation. This implies of an involvement of SIRT6 in neuronal differentiation and maturation within the hippocampus. This work adds to the expanding body of knowledge on the regulatory mechanisms underlying adult hippocampal neurogenesis, and describes novel roles for SIRT6 as a regulator of cell fate during adult hippocampal neurogenesis.

  7. Adult Hippocampal Neurogenesis in Parkinson’s Disease: Impact on Neuronal Survival and Plasticity

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    Martin Regensburger

    2014-01-01

    Full Text Available In Parkinson’s disease (PD and other synucleinopathies, chronic neurodegeneration occurs within different areas of the central nervous system leading to progressive motor and nonmotor symptoms. The symptomatic treatment options that are currently available do not slow or halt disease progression. This highlights the need of a better understanding of disease mechanisms and disease models. The generation of newborn neurons in the adult hippocampus and in the subventricular zone/olfactory bulb system is affected by many different regulators and possibly involved in memory processing, depression, and olfaction, symptoms which commonly occur in PD. The pathology of the adult neurogenic niches in human PD patients is still mostly elusive, but different preclinical models have shown profound alterations of adult neurogenesis. Alterations in stem cell proliferation, differentiation, and survival as well as neurite outgrowth and spine formation have been related to different aspects in PD pathogenesis. Therefore, neurogenesis in the adult brain provides an ideal model to study disease mechanisms and compounds. In addition, adult newborn neurons have been proposed as a source of endogenous repair. Herein, we review current knowledge about the adult neurogenic niches in PD and highlight areas of future research.

  8. 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.

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

    Science.gov (United States)

    Prokai-Tatrai, Katalin; Prokai, Laszlo; Simpkins, James W.; Jung, Marianna E.

    2009-01-01

    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. PMID:19468338

  10. Genistein suppresses the mitochondrial apoptotic pathway in hippocampal neurons in rats with Alzheimer's disease

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    Yan Wang

    2016-01-01

    Full Text Available Genistein is effective against amyloid-β toxicity, but the underlying mechanisms are unclear. We hypothesized that genistein may protect neurons by inhibiting the mitochondrial apoptotic pathway, and thereby play a role in the prevention of Alzheimer's disease. A rat model of Alzheimer's disease was established by intraperitoneal injection of D-galactose and intracerebral injection of amyloid-β peptide (25–35. In the genistein treatment groups, a 7-day pretreatment with genistein (10, 30, 90 mg/kg was given prior to establishing Alzheimer's disease model, for 49 consecutive days. Terminal deoxyribonucleotidyl transferase-mediated dUTP nick end labeling assay demonstrated a reduction in apoptosis in the hippocampus of rats treated with genistein. Western blot analysis showed that expression levels of capase-3, Bax and cytochrome c were decreased compared with the model group. Furthermore, immunohistochemical staining revealed reductions in cytochrome c and Bax immunoreactivity in these rats. Morris water maze revealed a substantial shortening of escape latency by genist-ein in Alzheimer's disease rats. These findings suggest that genistein decreases neuronal loss in the hippocampus, and improves learning and memory ability. The neuroprotective effects of genistein are associated with the inhibition of the mitochondrial apoptotic pathway, as shown by its ability to reduce levels of caspase-3, Bax and cytochrome c.

  11. Kaempferol attenuates the glutamate-induced oxidative stress in mouse-derived hippocampal neuronal HT22 cells.

    Science.gov (United States)

    Yang, Eun-Ju; Kim, Geum-Soog; Jun, Mira; Song, Kyung-Sik

    2014-07-25

    It is thought that the neuronal cell loss caused by oxidative stress is the primary mechanism underlying the pathogenesis of several neurodegenerative disorders. Glutamate is an endogenous neurotransmitter, but at high concentrations it can act as a neurotoxicant by increasing the intracellular levels of reactive oxygen species (ROS). Therefore, the development of factors that can attenuate glutamate-induced oxidative stress in neuronal cells is a good strategy by which new drugs could be discovered that may treat or prevent neurodegenerative diseases. Here, the neuroprotective effects of kaempferol (KF) isolated from the stems of butterbur (Petasites japonicus) were examined in glutamate-treated hippocampal neuronal cells (HT22). The administration of KF (25 μM) resulted in a significant increase in cell viability (105.18 ± 7.48%) compared with the control (100.00 ± 3.05%), while glutamate (5 mM) reduced cell viability by 39.94 ± 1.61%. The glutamate-induced calcium (Ca(2+)) influx (1.93 ± 0.08-fold) was significantly reduced by 0.89 ± 0.02-fold following the administration of 25 μM KF. Additionally, when HT22 cells were stressed with excessive glutamate, there was a 3.70 ± 0.01-fold increase in intracellular ROS generation, even though this was effectively attenuated by KF (25 μM, 0.72 ± 0.01-fold). The protective effects of KF in HT22 cells were later confirmed using a lactate dehydrogenase (LDH) assay and a FITC-annexin V/propidium iodide double staining procedure. These findings also revealed that the neuroprotective effects of KF are a result of the regulation of the expression levels of proteins, such as Bcl-2, Bid, apoptosis-inducing factor (AIF), and mitogen-activated protein kinase (MAPK). This is the first report to investigate the neuroprotective influence of KF in glutamate-treated HT22 cells. These data demonstrate that KF may be a useful candidate for pharmacological therapies that can prevent and treat neurodegenerative diseases such as

  12. Involvement of Adult Hippocampal Neurogenesis in Learning and Forgetting

    Science.gov (United States)

    Yau, Suk-yu; Li, Ang; So, Kwok-Fai

    2015-01-01

    Adult hippocampal neurogenesis is a process involving the continuous generation of newborn neurons in the hippocampus of adult animals. Mounting evidence has suggested that hippocampal neurogenesis contributes to some forms of hippocampus-dependent learning and memory; however, the detailed mechanism concerning how this small number of newborn neurons could affect learning and memory remains unclear. In this review, we discuss the relationship between adult-born neurons and learning and memory, with a highlight on recently discovered potential roles of neurogenesis in pattern separation and forgetting. PMID:26380120

  13. Effects of a tacrine-8-hydroxyquinoline hybrid (IQM-622) on Aβ accumulation and cell death: involvement in hippocampal neuronal loss in Alzheimer's disease.

    Science.gov (United States)

    Antequera, Desiree; Bolos, Marta; Spuch, Carlos; Pascual, Consuelo; Ferrer, Isidro; Fernandez-Bachiller, María Isabel; Rodríguez-Franco, María Isabel; Carro, Eva

    2012-06-01

    Several studies have implicated the enzyme acetylcholinesterase (AChE) as well as several biometals in the pathogenesis of Alzheimer's disease (AD). A multifunctional molecule, the hybrid tacrine-8-hydroxyquinoline (named IQM-622), displays cholinergic, antioxidant, copper-complexing and neuroprotective properties. Using in vitro and in vivo models, we investigated the modulating effects of IQM-622 on amyloid β-protein (Aβ)-induced pathology as well as on chemically induced neurodegeneration by domoic acid. In the first experimental model, we observed a significant decrease in brain Aβ deposits in IQM-622-treated APP/Ps1 mice for four weeks. Moreover, IQM-622 promoted the degradation of intracellular Aβ in astrocytes, and protected against Aβ toxicity in cultured astrocytes and neurons. These findings suggest that the neuroprotective effect of IQM-622 is not only related to AChE inhibition, but also involves other mechanisms, including the modulation of Aβ-degradation pathways in AD brain. In this study we also compare the neuronal loss in CA1 hippocampal field of AD patients and of mice treated with domoic acid, giving similar patterns. Thus, we used a second experimental model by killing hippocampal neurons by domoic acid damage, in which IQM-622 increased survival in the CA1 and dentate gyrus regions of the hippocampus. Our observations suggest that administration of IQM-622 may have significant beneficial effects in neurodegenerative diseases, including AD, which course with acute or progressive neuronal death. Copyright © 2012. Published by Elsevier Inc.

  14. Stereological analysis of the mediodorsal thalamic nucleus in schizophrenia: volume, neuron number, and cell types

    DEFF Research Database (Denmark)

    Dorph-Petersen, Karl-Anton; Pierri, Joseph N; Sun, Zhuoxin

    2004-01-01

    The mediodorsal thalamic nucleus (MD) is the principal relay nucleus for the prefrontal cortex, a brain region thought to be dysfunctional in schizophrenia. Several, but not all, postmortem studies of the MD in schizophrenia have reported decreased volume and total neuronal number. However......, it is not clear whether the findings are specific for schizophrenia nor is it known which subtypes of thalamic neurons are affected. We studied the left MD in 11 subjects with schizophrenia, 9 control subjects, and 12 subjects with mood disorders. Based on morphological criteria, we divided the neurons into two...... subclasses, presumably corresponding to projection neurons and local circuit neurons. We estimated MD volume and the neuron number of each subclass using methods based on modern unbiased stereological principles. We also estimated the somal volumes of each subclass using a robust, but biased, approach...

  15. Brilliant Blue G improves cognition in an animal model of Alzheimer's disease and inhibits amyloid-β-induced loss of filopodia and dendrite spines in hippocampal neurons.

    Science.gov (United States)

    Chen, X; Hu, J; Jiang, L; Xu, S; Zheng, B; Wang, C; Zhang, J; Wei, X; Chang, L; Wang, Q

    2014-10-24

    Deposits of amyloid-β (Aβ) protein are one of the hallmarks of Alzheimer's disease (AD). Numerous studies report that the Aβ peptide, especially in the oligomeric form, causes memory decline and other cognitive deficits. However, there have been very few effective interventions for termination or even delay of AD progression. Brilliant Blue G (BBG), a safe triphenylmethane dye and P2X7 antagonist, has been reported to have protective effects on neuroinflammation, ischemia, spinal injury and neurodegenerative disorders. Here we report that systematic administration of BBG diminishes spatial memory impairment and cognitive deficits in a mouse AD model produced by injecting soluble Aβ peptide into the hippocampal CA1 region. In addition, we show that Aβ-induced loss of filopodia and spine density in cultured hippocampal neurons was prevented by administration of BBG. We conclude that BBG prevents the learning and memory impairment and cognitive deficits induced by the toxicity of soluble Aβ, and improves the development of dendritic spines in hippocampal neurons in an AD model mouse. Considering the safety and blood-brain-barrier (BBB)-permeability of BBG, our data suggest a potential for BBG as a new therapy for AD. Copyright © 2014 IBRO. Published by Elsevier Ltd. All rights reserved.

  16. In vitro aging promotes endoplasmic reticulum (ER)-mitochondria Ca2+cross talk and loss of store-operated Ca2+entry (SOCE) in rat hippocampal neurons.

    Science.gov (United States)

    Calvo-Rodríguez, María; García-Durillo, Mónica; Villalobos, Carlos; Núñez, Lucía

    2016-11-01

    Aging is associated to cognitive decline and susceptibility to neuron death, two processes related recently to subcellular Ca 2+ homeostasis. Memory storage relies on mushroom spines stability that depends on store-operated Ca 2+ entry (SOCE). In addition, Ca 2+ transfer from endoplasmic reticulum (ER) to mitochondria sustains energy production but mitochondrial Ca 2+ overload promotes apoptosis. We have addressed whether SOCE and ER-mitochondria Ca 2+ transfer are influenced by culture time in long-term cultures of rat hippocampal neurons, a model of neuronal aging. We found that short-term cultured neurons show large SOCE, low Ca 2+ store content and no functional coupling between ER and mitochondria. In contrast, in long-term cultures reflecting aging neurons, SOCE is essentially lost, Stim1 and Orai1 are downregulated, Ca 2+ stores become overloaded, Ca 2+ release is enhanced, expression of the mitochondrial Ca 2+ uniporter (MCU) increases and most Ca 2+ released from the ER is transferred to mitochondria. These results suggest that neuronal aging is associated to increased ER-mitochondrial cross talking and loss of SOCE. This subcellular Ca 2+ remodeling might contribute to cognitive decline and susceptibility to neuron cell death in the elderly. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Dynamin-related protein 1 is required for normal mitochondrial bioenergetic and synaptic function in CA1 hippocampal neurons.

    Science.gov (United States)

    Shields, L Y; Kim, H; Zhu, L; Haddad, D; Berthet, A; Pathak, D; Lam, M; Ponnusamy, R; Diaz-Ramirez, L G; Gill, T M; Sesaki, H; Mucke, L; Nakamura, K

    2015-04-16

    Disrupting particular mitochondrial fission and fusion proteins leads to the death of specific neuronal populations; however, the normal functions of mitochondrial fission in neurons are poorly understood, especially in vivo, which limits the understanding of mitochondrial changes in disease. Altered activity of the central mitochondrial fission protein dynamin-related protein 1 (Drp1) may contribute to the pathophysiology of several neurologic diseases. To study Drp1 in a neuronal population affected by Alzheimer's disease (AD), stroke, and seizure disorders, we postnatally deleted Drp1 from CA1 and other forebrain neurons in mice (CamKII-Cre, Drp1lox/lox (Drp1cKO)). Although most CA1 neurons survived for more than 1 year, their synaptic transmission was impaired, and Drp1cKO mice had impaired memory. In Drp1cKO cell bodies, we observed marked mitochondrial swelling but no change in the number of mitochondria in individual synaptic terminals. Using ATP FRET sensors, we found that cultured neurons lacking Drp1 (Drp1KO) could not maintain normal levels of mitochondrial-derived ATP when energy consumption was increased by neural activity. These deficits occurred specifically at the nerve terminal, but not the cell body, and were sufficient to impair synaptic vesicle cycling. Although Drp1KO increased the distance between axonal mitochondria, mitochondrial-derived ATP still decreased similarly in Drp1KO boutons with and without mitochondria. This indicates that mitochondrial-derived ATP is rapidly dispersed in Drp1KO axons, and that the deficits in axonal bioenergetics and function are not caused by regional energy gradients. Instead, loss of Drp1 compromises the intrinsic bioenergetic function of axonal mitochondria, thus revealing a mechanism by which disrupting mitochondrial dynamics can cause dysfunction of axons.

  18. [Nonuniform distribution and contribution of the P- and P/Q-type calcium channels to short-term inhibitory synaptic transmission in cultured hippocampal neurons].

    Science.gov (United States)

    Mizerna, O P; Fedulova, S A; Veselovs'kyĭ, M S

    2010-01-01

    In the present study, we investigated the sensitivity of GABAergic short-term plasticity to the selective P- and P/Q-type calcium channels blocker omega-agatoxin-IVA. To block the P-type channels we used 30 nM of this toxin and 200 nM of the toxin was used to block the P/Q channel types. The evoked inhibitory postsynaptic currents (eIPSC) were studied using patch-clamp technique in whole-cell configuration in postsynaptic neuron and local extracellular stimulation of single presynaptic axon by rectangular pulse. The present data show that the contribution of P- and P/Q-types channels to GABAergic synaptic transmission in cultured hippocampal neurons are 30% and 45%, respectively. It was shown that the mediate contribution of the P- and P/Q-types channels to the amplitudes of eIPSC is different to every discovered neuron. It means that distribution of these channels is non-uniform. To study the short-term plasticity of inhibitory synaptic transmission, axons of presynaptic neurons were paired-pulse stimulated with the interpulse interval of 150 ms. Neurons demonstrated both the depression and facilitation. The application of 30 nM and 200 nM of the blocker decreased the depression and increased facilitation to 8% and 11%, respectively. In addition, we found that the mediate contribution of the P- and P/Q-types channels to realization of synaptic transmission after the second stimuli is 4% less compared to that after the first one. Therefore, blocking of both P- and P/Q-types calcium channels can change the efficiency of synaptic transmission. In this instance it facilitates realization of the transmission via decreased depression or increased facilitation. These results confirm that the P- and P/Q-types calcium channels are involved in regulation of the short-term inhibitory synaptic plasticity in cultured hippocampal neurons.

  19. Fe(2+) and Fe(3+) in micromolar concentrations modulate glycine-induced Cl(-) current in rat hippocampal neurons.

    Science.gov (United States)

    Solntseva, E I; Bukanova, J V; Kondratenko, R V; Skrebitsky, V G

    2015-06-01

    The effects of Fe(2+) and Fe(3+) on glycine-activated chloride current (IGly) were studied in rat isolated pyramidal hippocampal neurons using patch-clamp technique in whole-cell configuration. 25, 100 or 500 μM glycine was applied for 600 ms with 40s intervals. Fe(2+) and Fe(3+) were co-applied with glycine in the range of concentrations of 0.01-100 μM. We found that Fe(2+) and Fe(3+) affected IGly in a similar manner. Two types of effects of iron on IGly were observed. In low concentrations (0.1 μM) Fe ions caused an acceleration of the IGly desensitization, and the effect was more pronounced for IGly induced by 100 and 500 μM glycine than by 25 μM glycine. Higher Fe concentrations (1-100 μM) decreased the peak amplitude of IGly with weak influence on its kinetics. The values of IC50 of the effect were close to 10 μM for all glycine concentrations tested. The effect of iron on IGly peak did not depend on the membrane potential. This inhibition was noncompetitive and voltage-independent, suggesting that Fe ions do not exert their action on the agonist binding site of GlyRs or block the channel pore. An important characteristic of both effects of Fe was their progressive development during repetitive Fe applications (use-dependence). Our results suggest an existence of at least two binding sites for Fe ions which vary in affinity and mechanism of action, with the low-affinity site suppressing the activity of the high-affinity one. Physiological implication of our observations is that Fe ions in low micromolar concentrations can suppress tonic inhibition and cause hyperexcitability in hippocampus. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. Hypoxia-induced down-regulation of neprilysin by histone modification in mouse primary cortical and hippocampal neurons.

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    Zheng Wang

    Full Text Available Amyloid β-peptide (Aβ accumulation leads to neurodegeneration and Alzheimer's disease (AD. Aβ metabolism is a dynamic process in the Aβ production and clearance that requires neprilysin (NEP and other enzymes to degrade Aβ. It has been reported that NEP expression is significantly decreased in the brain of AD patients. Previously we have documented hypoxia is a risk factor for Aβ generation in vivo and in vitro through increasing Aβ generation by altering β-cleavage and γ-cleavage of APP and down-regulating NEP, and causing tau hyperphosphorylation. Here, we investigated the molecular mechanisms of hypoxia-induced down-regulation of NEP. We found a significant decrease in NEP expression at the mRNA and protein levels after hypoxic treatment in mouse primary cortical and hippocampal neurons. Chromatin immunoprecipitation (ChIP assays and relative quantitative PCR (q-PCR revealed an increase of histone H3-lysine9 demethylation (H3K9me2 and a decrease of H3 acetylation (H3-Ace in the NEP promoter regions following hypoxia. In addition, we found that hypoxia caused up-regulation of histone methyl transferase (HMT G9a and histone deacetylases (HDACs HDAC-1. Decreased expression of NEP during hypoxia can be prevented by application with the epigenetic regulators 5-Aza-2'-deoxycytidine (5-Aza, HDACs inhibitor sodium valproate (VA, and siRNA-mediated knockdown of G9a or HDAC1. DNA methylation PCR data do not support that hypoxia affects the methylation of NEP promoters. This study suggests that hypoxia may down-regulate NEP by increasing H3K9me2 and decreasing H3-Ace modulation.

  1. Effects of 1950 MHz radiofrequency electromagnetic fields on Aβ processing in human neuroblastoma and mouse hippocampal neuronal cells

    Science.gov (United States)

    Park, Jeongyeon; Kwon, Jong Hwa; Kim, Nam

    2018-01-01

    Abstract Alzheimer’s disease (AD) is a neurodegenerative disease leading to progressive loss of memory and other cognitive functions. One of the well-known pathological markers of AD is the accumulation of amyloid-beta protein (Aβ), and its plaques, in the brain. Recent studies using Tg-5XFAD mice as a model of AD have reported that exposure to radiofrequency electromagnetic fields (RF-EMF) from cellular phones reduced Aβ plaques in the brain and showed beneficial effects on AD. In this study, we examined whether exposure to 1950 MHz RF-EMF affects Aβ processing in neural cells. We exposed HT22 mouse hippocampal neuronal cells and SH-SY5Y human neuroblastoma cells to RF-EMF (SAR 6 W/kg) for 2 h per day for 3 days, and analyzed the mRNA and protein expression of the key genes related to Aβ processing. When exposed to RF-EMF, mRNA levels of APP, BACE1, ADAM10 and PSEN1 were decreased in HT22, but the mRNA level of APP was not changed in SH-SY5Y cells. The protein expression of APP and BACE1, as well as the secreted Aβ peptide, was not significantly different between RF-EMF–exposed 7w-PSML, HT22 and SH-SY5Y cells and the unexposed controls. These observations suggest that RF-EMF exposure may not have a significant physiological effect on Aβ processing of neural cells in the short term. However, considering that we only exposed HT22 and SH-SY5Y cells to RF-EMF for 2 h per day for 3 days, we cannot exclude the possibility that 1950 MHz RF-EMF induces physiological change in Aβ processing with long-term and continuous exposure. PMID:29040655

  2. 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

  3. Cell biology in neuroscience: Architects in neural circuit design: glia control neuron numbers and connectivity.

    Science.gov (United States)

    Corty, Megan M; Freeman, Marc R

    2013-11-11

    Glia serve many important functions in the mature nervous system. In addition, these diverse cells have emerged as essential participants in nearly all aspects of neural development. Improved techniques to study neurons in the absence of glia, and to visualize and manipulate glia in vivo, have greatly expanded our knowledge of glial biology and neuron-glia interactions during development. Exciting studies in the last decade have begun to identify the cellular and molecular mechanisms by which glia exert control over neuronal circuit formation. Recent findings illustrate the importance of glial cells in shaping the nervous system by controlling the number and connectivity of neurons.

  4. Cannabidiol attenuates OGD/R-induced damage by enhancing mitochondrial bioenergetics and modulating glucose metabolism via pentose-phosphate pathway in hippocampal neurons

    Directory of Open Access Journals (Sweden)

    Shanshan Sun

    2017-04-01

    Full Text Available Deficient bioenergetics and diminished redox conservation have been implicated in the development of cerebral ischemia/reperfusion injury. In this study, the mechanisms underlying the neuroprotective effects of cannabidiol (CBD, a nonpsychotropic compound derived from Cannabis sativa with FDA-approved antiepilepsy properties, were studied in vitro using an oxygen–glucose-deprivation/reperfusion (OGD/R model in a mouse hippocampal neuronal cell line. CBD supplementation during reperfusion rescued OGD/R-induced cell death, attenuated intracellular ROS generation and lipid peroxidation, and simultaneously reversed the abnormal changes in antioxidant biomarkers. Using the Seahorse XFe24 Extracellular Flux Analyzer, we found that CBD significantly improved basal respiration, ATP-linked oxygen consumption rate, and the spare respiratory capacity, and augmented glucose consumption in OGD/R-injured neurons. The activation of glucose 6-phosphate dehydrogenase and the preservation of the NADPH/NADP+ ratio implies that the pentose-phosphate pathway is stimulated by CBD, thus protecting hippocampal neurons from OGD/R injury. This study is the first to document the neuroprotective effects of CBD against OGD/R insult, which depend in part on attenuating oxidative stress, enhancing mitochondrial bioenergetics, and modulating glucose metabolism via the pentose-phosphate pathway, thus preserving both energy and the redox balance.

  5. Cannabidiol attenuates OGD/R-induced damage by enhancing mitochondrial bioenergetics and modulating glucose metabolism via pentose-phosphate pathway in hippocampal neurons.

    Science.gov (United States)

    Sun, Shanshan; Hu, Fangyuan; Wu, Jihong; Zhang, Shenghai

    2017-04-01

    Deficient bioenergetics and diminished redox conservation have been implicated in the development of cerebral ischemia/reperfusion injury. In this study, the mechanisms underlying the neuroprotective effects of cannabidiol (CBD), a nonpsychotropic compound derived from Cannabis sativa with FDA-approved antiepilepsy properties, were studied in vitro using an oxygen-glucose-deprivation/reperfusion (OGD/R) model in a mouse hippocampal neuronal cell line. CBD supplementation during reperfusion rescued OGD/R-induced cell death, attenuated intracellular ROS generation and lipid peroxidation, and simultaneously reversed the abnormal changes in antioxidant biomarkers. Using the Seahorse XF e 24 Extracellular Flux Analyzer, we found that CBD significantly improved basal respiration, ATP-linked oxygen consumption rate, and the spare respiratory capacity, and augmented glucose consumption in OGD/R-injured neurons. The activation of glucose 6-phosphate dehydrogenase and the preservation of the NADPH/NADP + ratio implies that the pentose-phosphate pathway is stimulated by CBD, thus protecting hippocampal neurons from OGD/R injury. This study is the first to document the neuroprotective effects of CBD against OGD/R insult, which depend in part on attenuating oxidative stress, enhancing mitochondrial bioenergetics, and modulating glucose metabolism via the pentose-phosphate pathway, thus preserving both energy and the redox balance. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  6. Hyperactive mTOR signals in the proopiomelanocortin-expressing hippocampal neurons cause age-dependent epilepsy and premature death in mice.

    Science.gov (United States)

    Matsushita, Yuki; Sakai, Yasunari; Shimmura, Mitsunori; Shigeto, Hiroshi; Nishio, Miki; Akamine, Satoshi; Sanefuji, Masafumi; Ishizaki, Yoshito; Torisu, Hiroyuki; Nakabeppu, Yusaku; Suzuki, Akira; Takada, Hidetoshi; Hara, Toshiro

    2016-03-10

    Epilepsy is a frequent comorbidity in patients with focal cortical dysplasia (FCD). Recent studies utilizing massive sequencing data identified subsets of genes that are associated with epilepsy and FCD. AKT and mTOR-related signals have been recently implicated in the pathogenic processes of epilepsy and FCD. To clarify the functional roles of the AKT-mTOR pathway in the hippocampal neurons, we generated conditional knockout mice harboring the deletion of Pten (Pten-cKO) in Proopiomelanocortin-expressing neurons. The Pten-cKO mice developed normally until 8 weeks of age, then presented generalized seizures at 8-10 weeks of age. Video-monitored electroencephalograms detected paroxysmal discharges emerging from the cerebral cortex and hippocampus. These mice showed progressive hypertrophy of the dentate gyrus (DG) with increased expressions of excitatory synaptic markers (Psd95, Shank3 and Homer). In contrast, the expression of inhibitory neurons (Gad67) was decreased at 6-8 weeks of age. Immunofluorescence studies revealed the abnormal sprouting of mossy fibers in the DG of the Pten-cKO mice prior to the onset of seizures. The treatment of these mice with an mTOR inhibitor rapamycin successfully prevented the development of seizures and reversed these molecular phenotypes. These data indicate that the mTOR pathway regulates hippocampal excitability in the postnatal brain.

  7. Anti-Epileptic Effect of Ganoderma Lucidum Polysaccharides by Inhibition of Intracellular Calcium Accumulation and Stimulation of Expression of CaMKII α in Epileptic Hippocampal Neurons

    Science.gov (United States)

    Wang, Shu-Qiu; Li, Xiao-Jie; Qiu, Hong-Bin; Jiang, Zhi-Mei; Simon, Maria; Ma, Xiao-Ru; Liu, Lei; Liu, Jun-Xing; Wang, Fang-Fang; Liang, Yan-Feng; Wu, Jia-Mei; Di, Wei-Hua; Zhou, Shaobo

    2014-01-01

    Purpose To investigate the mechanism of the anti-epileptic effect of Ganoderma lucidum polysaccharides (GLP), the changes of intracellular calcium and CaMK II α expression in a model of epileptic neurons were investigated. Method Primary hippocampal neurons were divided into: 1) Control group, neurons were cultured with Neurobasal medium, for 3 hours; 2) Model group I: neurons were incubated with Mg2+ free medium for 3 hours; 3) Model group II: neurons were incubated with Mg2+ free medium for 3 hours then cultured with the normal medium for a further 3 hours; 4) GLP group I: neurons were incubated with Mg2+ free medium containing GLP (0.375 mg/ml) for 3 hours; 5) GLP group II: neurons were incubated with Mg2+ free medium for 3 hours then cultured with a normal culture medium containing GLP for a further 3 hours. The CaMK II α protein expression was assessed by Western-blot. Ca2+ turnover in neurons was assessed using Fluo-3/AM which was added into the replacement medium and Ca2+ turnover was observed under a laser scanning confocal microscope. Results The CaMK II α expression in the model groups was less than in the control groups, however, in the GLP groups, it was higher than that observed in the model group. Ca2+ fluorescence intensity in GLP group I was significantly lower than that in model group I after 30 seconds, while in GLP group II, it was reduced significantly compared to model group II after 5 minutes. Conclusion GLP may inhibit calcium overload and promote CaMK II α expression to protect epileptic neurons. PMID:25010576

  8. Anti-epileptic effect of Ganoderma lucidum polysaccharides by inhibition of intracellular calcium accumulation and stimulation of expression of CaMKII α in epileptic hippocampal neurons.

    Directory of Open Access Journals (Sweden)

    Shu-Qiu Wang

    Full Text Available To investigate the mechanism of the anti-epileptic effect of Ganoderma lucidum polysaccharides (GLP, the changes of intracellular calcium and CaMK II α expression in a model of epileptic neurons were investigated.Primary hippocampal neurons were divided into: 1 Control group, neurons were cultured with Neurobasal medium, for 3 hours; 2 Model group I: neurons were incubated with Mg(2+ free medium for 3 hours; 3 Model group II: neurons were incubated with Mg(2+ free medium for 3 hours then cultured with the normal medium for a further 3 hours; 4 GLP group I: neurons were incubated with Mg(2+ free medium containing GLP (0.375 mg/ml for 3 hours; 5 GLP group II: neurons were incubated with Mg(2+ free medium for 3 hours then cultured with a normal culture medium containing GLP for a further 3 hours. The CaMK II α protein expression was assessed by Western-blot. Ca(2+ turnover in neurons was assessed using Fluo-3/AM which was added into the replacement medium and Ca(2+ turnover was observed under a laser scanning confocal microscope.The CaMK II α expression in the model groups was less than in the control groups, however, in the GLP groups, it was higher than that observed in the model group. Ca(2+ fluorescence intensity in GLP group I was significantly lower than that in model group I after 30 seconds, while in GLP group II, it was reduced significantly compared to model group II after 5 minutes.GLP may inhibit calcium overload and promote CaMK II α expression to protect epileptic neurons.

  9. Decreased number of oxytocin neurons in the paraventricular nucleus of the human hypothalamus in AIDS

    NARCIS (Netherlands)

    Purba, J. S.; Hofman, M. A.; Portegies, P.; Troost, D.; Swaab, D. F.

    1993-01-01

    The number of immunocytochemically identified vasopressin (AVP) and oxytocin (OXT) neurons was determined morphometrically in the paraventricular nucleus of the hypothalamus of 20 acquired immunodeficiency syndrome (AIDS) patients and 10 controls. The AIDS group consisted of 14 homosexual males (age

  10. Glycine receptor in rat hippocampal and spinal cord neurons as a molecular target for rapid actions of 17-β-estradiol

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    Liu Chun-Feng

    2009-01-01

    Full Text Available Abstract Glycine receptors (GlyRs play important roles in regulating hippocampal neural network activity and spinal nociception. Here we show that, in cultured rat hippocampal (HIP and spinal dorsal horn (SDH neurons, 17-β-estradiol (E2 rapidly and reversibly reduced the peak amplitude of whole-cell glycine-activated currents (IGly. In outside-out membrane patches from HIP neurons devoid of nuclei, E2 similarly inhibited IGly, suggesting a non-genomic characteristic. Moreover, the E2 effect on IGly persisted in the presence of the calcium chelator BAPTA, the protein kinase inhibitor staurosporine, the classical ER (i.e. ERα and ERβ antagonist tamoxifen, or the G-protein modulators, favoring a direct action of E2 on GlyRs. In HEK293 cells expressing various combinations of GlyR subunits, E2 only affected the IGly in cells expressing α2, α2β or α3β subunits, suggesting that either α2-containing or α3β-GlyRs mediate the E2 effect observed in neurons. Furthermore, E2 inhibited the GlyR-mediated tonic current in pyramidal neurons of HIP CA1 region, where abundant GlyR α2 subunit is expressed. We suggest that the neuronal GlyR is a novel molecular target of E2 which directly inhibits the function of GlyRs in the HIP and SDH regions. This finding may shed new light on premenstrual dysphoric disorder and the gender differences in pain sensation at the CNS level.

  11. Characterization of two novel nuclear BTB/POZ domain zinc finger isoforms. Association with differentiation of hippocampal neurons, cerebellar granule cells, and macroglia

    DEFF Research Database (Denmark)

    Mitchelmore, Cathy; Kjaerulff, Karen M; Pedersen, Hans C

    2002-01-01

    BTB/POZ (broad complex tramtrack bric-a-brac/poxvirus and zinc finger) zinc finger factors are a class of nuclear DNA-binding proteins involved in development, chromatin remodeling, and cancer. However, BTB/POZ domain zinc finger factors linked to development of the mammalian cerebral cortex......, cerebellum, and macroglia have not been described previously. We report here the isolation and characterization of two novel nuclear BTB/POZ domain zinc finger isoforms, designated HOF(L) and HOF(S), that are specifically expressed in early hippocampal neurons, cerebellar granule cells, and gliogenic...

  12. IP{sub 3}-dependent intracellular Ca{sup 2+} release is required for cAMP-induced c-fos expression in hippocampal neurons

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wenting; Tingare, Asmita; Ng, David Chi-Heng [Department of Pharmacology, University of Cambridge (United Kingdom); Johnson, Hong W.; Schell, Michael J. [Department of Pharmacology, Uniformed Services University, Bethesda (United States); Lord, Rebecca L. [Department of Biology, University of York (United Kingdom); Chawla, Sangeeta, E-mail: sangeeta.chawla@york.ac.uk [Department of Pharmacology, University of Cambridge (United Kingdom); Department of Biology, University of York (United Kingdom)

    2012-08-24

    Highlights: Black-Right-Pointing-Pointer cAMP-induced c-fos expression in hippocampal neurons requires a submembraneous Ca{sup 2+} pool. Black-Right-Pointing-Pointer The submembraneous Ca{sup 2+} pool derives from intracellular ER stores. Black-Right-Pointing-Pointer Expression of IP{sub 3}-metabolizing enzymes inhibits cAMP-induced c-fos expression. Black-Right-Pointing-Pointer SRE-mediated and CRE-mediated gene expression is sensitive to IP{sub 3}-metabolizing enzymes. Black-Right-Pointing-Pointer Intracellular Ca{sup 2+} release is required for cAMP-induced nuclear translocation of TORC1. -- Abstract: Ca{sup 2+} and cAMP are widely used in concert by neurons to relay signals from the synapse to the nucleus, where synaptic activity modulates gene expression required for synaptic plasticity. Neurons utilize different transcriptional regulators to integrate information encoded in the spatiotemporal dynamics and magnitude of Ca{sup 2+} and cAMP signals, including some that are Ca{sup 2+}-responsive, some that are cAMP-responsive and some that detect coincident Ca{sup 2+} and cAMP signals. Because Ca{sup 2+} and cAMP can influence each other's amplitude and spatiotemporal characteristics, we investigated how cAMP acts to regulate gene expression when increases in intracellular Ca{sup 2+} are buffered. We show here that cAMP-mobilizing stimuli are unable to induce expression of the immediate early gene c-fos in hippocampal neurons in the presence of the intracellular Ca{sup 2+} buffer BAPTA-AM. Expression of enzymes that attenuate intracellular IP{sub 3} levels also inhibited cAMP-dependent c-fos induction. Synaptic activity induces c-fos transcription through two cis regulatory DNA elements - the CRE and the SRE. We show here that in response to cAMP both CRE-mediated and SRE-mediated induction of a luciferase reporter gene is attenuated by IP{sub 3} metabolizing enzymes. Furthermore, cAMP-induced nuclear translocation of the CREB coactivator TORC1 was inhibited

  13. PSD95 suppresses dendritic arbor development in mature hippocampal neurons by occluding the clustering of NR2B-NMDA receptors.

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    Fernando J Bustos

    Full Text Available Considerable evidence indicates that the NMDA receptor (NMDAR subunits NR2A and NR2B are critical mediators of synaptic plasticity and dendritogenesis; however, how they differentially regulate these processes is unclear. Here we investigate the roles of the NR2A and NR2B subunits, and of their scaffolding proteins PSD-95 and SAP102, in remodeling the dendritic architecture of developing hippocampal neurons (2-25 DIV. Analysis of the dendritic architecture and the temporal and spatial expression patterns of the NMDARs and anchoring proteins in immature cultures revealed a strong positive correlation between synaptic expression of the NR2B subunit and dendritogenesis. With maturation, the pruning of dendritic branches was paralleled by a strong reduction in overall and synaptic expression of NR2B, and a significant elevation in synaptic expression of NR2A and PSD95. Using constructs that alter the synaptic composition, we found that either over-expression of NR2B or knock-down of PSD95 by shRNA-PSD95 augmented dendritogenesis in immature neurons. Reactivation of dendritogenesis could also be achieved in mature cultured neurons, but required both manipulations simultaneously, and was accompanied by increased dendritic clustering of NR2B. Our results indicate that the developmental increase in synaptic expression of PSD95 obstructs the synaptic clustering of NR2B-NMDARs, and thereby restricts reactivation of dendritic branching. Experiments with shRNA-PSD95 and chimeric NR2A/NR2B constructs further revealed that C-terminus of the NR2B subunit (tail was sufficient to induce robust dendritic branching in mature hippocampal neurons, and suggest that the NR2B tail is important in recruiting calcium-dependent signaling proteins and scaffolding proteins necessary for dendritogenesis.

  14. Age-related toxicity of amyloid-beta associated with increased pERK and pCREB in primary hippocampal neurons: reversal by blueberry extract

    Science.gov (United States)

    Brewer, Gregory J.; Torricelli, John R.; Lindsey, Amanda L.; Kunz, Elizabeth Z.; Neuman, A.; Fisher, Derek R.; Joseph, James A.

    2009-01-01

    Further clarification is needed to address the paradox that memory formation, aging and neurodegeneration all involve calcium influx, oxyradical production (ROS) and activation of certain signaling pathways. In aged rats and in APP/PS-1 mice, cognitive and hippocampal Ca2+ dysregulation were reversed by food supplementation with a high antioxidant blueberry extract. Here, we studied whether neurons were an important target of blueberry extract and whether the mechanism involved altered ROS signaling through MAPK and CREB, pathways known to be activated in response to amyloid-beta. Primary hippocampal neurons were isolated and cultured from embryonic, middle-age or old-age (24 months) rats. Blueberry extract was found to be equally neuroprotective against amyloid-beta neurotoxicity at all ages. Increases in amyloid-beta toxicity with age were associated with age-related increases in immunoreactivity of neurons to pERK and an age-independent increase in pCREB. Treatment with blueberry extract strongly inhibited these increases in parallel with neuroprotection. Simultaneous labeling for ROS and for glutathione with dichlorofluorescein and monocholorobimane showed a mechanism of action of blueberry extract to involve transient ROS generation with an increase in the redox buffer, glutathione. We conclude that the increased age-related susceptibility of old-age neurons to amyloid-beta toxicity may be due to higher levels of activation of pERK and pCREB pathways that can be protected by blueberry extract through inhibition of both these pathways through an ROS stress response. These results suggest that the beneficial effects of blueberry extract may involve transient stress signaling and ROS protection that may translate into improved cognition in aging rats and APP/PS1 mice given blueberry extract. PMID:19954954

  15. Vitamin B1-deficient mice show impairment of hippocampus-dependent memory formation and loss of hippocampal neurons and dendritic spines: potential microendophenotypes of Wernicke-Korsakoff syndrome.

    Science.gov (United States)

    Inaba, Hiroyoshi; Kishimoto, Takuya; Oishi, Satoru; Nagata, Kan; Hasegawa, Shunsuke; Watanabe, Tamae; Kida, Satoshi

    2016-12-01

    Patients with severe Wernicke-Korsakoff syndrome (WKS) associated with vitamin B1 (thiamine) deficiency (TD) show enduring impairment of memory formation. The mechanisms of memory impairment induced by TD remain unknown. Here, we show that hippocampal degeneration is a potential microendophenotype (an endophenotype of brain disease at the cellular and synaptic levels) of WKS in pyrithiamine-induced thiamine deficiency (PTD) mice, a rodent model of WKS. PTD mice show deficits in the hippocampus-dependent memory formation, although they show normal hippocampus-independent memory. Similarly with WKS, impairments in memory formation did not recover even at 6 months after treatment with PTD. Importantly, PTD mice exhibit a decrease in neurons in the CA1, CA3, and dentate gyrus (DG) regions of the hippocampus and reduced density of wide dendritic spines in the DG. Our findings suggest that TD induces hippocampal degeneration, including the loss of neurons and spines, thereby leading to enduring impairment of hippocampus-dependent memory formation.

  16. Cell Type-Specific mRNA Dysregulation in Hippocampal CA1 Pyramidal Neurons of the Fragile X Syndrome Mouse Model

    Directory of Open Access Journals (Sweden)

    Laura Ceolin

    2017-10-01

    Full Text Available Fragile X syndrome (FXS is a genetic disorder due to the silencing of the Fmr1 gene, causing intellectual disability, seizures, hyperactivity, and social anxiety. All these symptoms result from the loss of expression of the RNA binding protein fragile X mental retardation protein (FMRP, which alters the neurodevelopmental program to abnormal wiring of specific circuits. Aberrant mRNAs translation associated with the loss of Fmr1 product is widely suspected to be in part the cause of FXS. However, precise gene expression changes involved in this disorder have yet to be defined. The objective of this study was to identify the set of mistranslated mRNAs that could contribute to neurological deficits in FXS. We used the RiboTag approach and RNA sequencing to provide an exhaustive listing of genes whose mRNAs are differentially translated in hippocampal CA1 pyramidal neurons as the integrative result of FMRP loss and subsequent neurodevelopmental adaptations. Among genes differentially regulated between adult WT and Fmr1−/y mice, we found enrichment in FMRP-binders but also a majority of non-FMRP-binders. Interestingly, both up- and down-regulation of specific gene expression is relevant to fully understand the molecular deficiencies triggering FXS. More importantly, functional genomic analysis highlighted the importance of genes involved in neuronal connectivity. Among them, we show that Klk8 altered expression participates in the abnormal hippocampal dendritic spine maturation observed in a mouse model of FXS.

  17. High-Speed Imaging Reveals Opposing Effects of Chronic Stress and Antidepressants on Neuronal Activity Propagation through the Hippocampal Trisynaptic Circuit

    Directory of Open Access Journals (Sweden)

    Jens eStepan

    2015-11-01

    Full Text Available Antidepressants (ADs are used as first-line treatment for most stress-related psychiatric disorders. The alterations in brain circuit dynamics that can arise from stress exposure and underlie therapeutic actions of ADs remain, however, poorly understood. Here, enabled by a recently developed voltage-sensitive dye imaging assay in mouse brain slices, we examined the impact of chronic stress and concentration-dependent effects of eight clinically used ADs (belonging to different chemical/functional classes on evoked neuronal activity propagations through the hippocampal trisynaptic circuitry (HTC: perforant path - dentate gyrus - area CA3 - area CA1. Exposure of mice to chronic social defeat stress led to markedly weakened activity propagations (HTC-Waves. In contrast, at concentrations in the low micromolar range, all ADs, which were bath applied to slices, caused an amplification of HTC-Waves in CA regions (invariably in area CA1. The fast-acting antidepressant ketamine, the mood stabilizer lithium, and brain-derived neurotrophic factor (BDNF exerted comparable enhancing effects, whereas the antipsychotic haloperidol and the anxiolytic diazepam attenuated HTC-Waves. Collectively, we provide direct experimental evidence that chronic stress can depress neuronal signal flow through the HTC and demonstrate shared opposing effects of ADs. Thus, our study points to a circuit-level mechanism of ADs to counteract stress-induced impairment of hippocampal network function. However, the observed effects of ADs are impossible to depend on enhanced neurogenesis.

  18. Characterization of l-Theanine Excitatory Actions on Hippocampal Neurons: Toward the Generation of Novel N-Methyl-d-aspartate Receptor Modulators Based on Its Backbone.

    Science.gov (United States)

    Sebih, Fatiha; Rousset, Matthieu; Bellahouel, Salima; Rolland, Marc; de Jesus Ferreira, Marie Celeste; Guiramand, Janique; Cohen-Solal, Catherine; Barbanel, Gérard; Cens, Thierry; Abouazza, Mohammed; Tassou, Adrien; Gratuze, Maud; Meusnier, Céline; Charnet, Pierre; Vignes, Michel; Rolland, Valérie

    2017-08-16

    l-Theanine (or l-γ-N-ethyl-glutamine) is the major amino acid found in Camellia sinensis. It has received much attention because of its pleiotropic physiological and pharmacological activities leading to health benefits in humans, especially. We describe here a new, easy, efficient, and environmentally friendly chemical synthesis of l-theanine and l-γ-N-propyl-Gln and their corresponding d-isomers. l-Theanine, and its derivatives obtained so far, exhibited partial coagonistic action at N-methyl-d-aspartate (NMDA) receptors, with no detectable agonist effect at other glutamate receptors, on cultured hippocampal neurons. This activity was retained on NMDA receptors expressed in Xenopus oocytes. In addition, both GluN2A and GluN2B containing NMDA receptors were equally modulated by l-theanine. The stereochemical change from l-theanine to d-theanine along with the substitution of the ethyl for a propyl moiety in the γ-N position of l- and d-theanine significantly enhanced the biological efficacy, as measured on cultured hippocampal neurons. l-Theanine structure thus represents an interesting backbone to develop novel NMDA receptor modulators.

  19. Escitalopram attenuates β-amyloid-induced tau hyperphosphorylation in primary hippocampal neurons through the 5-HT1A receptor mediated Akt/GSK-3β pathway.

    Science.gov (United States)

    Wang, Yan-Juan; Ren, Qing-Guo; Gong, Wei-Gang; Wu, Di; Tang, Xiang; Li, Xiao-Li; Wu, Fang-Fang; Bai, Feng; Xu, Lin; Zhang, Zhi-Jun

    2016-03-22

    Tau hyperphosphorylation is an important pathological feature of Alzheimer's disease (AD). To investigate whether escitalopram could inhibit amyloid-β (Aβ)-induced tau hyperphosphorylation and the underlying mechanisms, we treated the rat primary hippocampal neurons with Aβ1-42 and examined the effect of escitalopram on tau hyperphosphorylation. Results showed that escitalopram decreased Aβ1-42-induced tau hyperphosphorylation. In addition, escitalopram activated the Akt/GSK-3β pathway, and the PI3K inhibitor LY294002 blocked the attenuation of tau hyperphosphorylation induced by escitalopram. Moreover, the 5-HT1A receptor agonist 8-OH-DPAT also activated the Akt/GSK-3β pathway and decreased Aβ1-42-induced tau hyperphosphorylation. Furthermore, the 5-HT1A receptor antagonist WAY-100635 blocked the activation of Akt/GSK-3β pathway and the attenuation of tau hyperphosphorylation induced by escitalopram. Finally, escitalopram improved Aβ1-42 induced impairment of neurite outgrowth and spine density, and reversed Aβ1-42 induced reduction of synaptic proteins. Our results demonstrated that escitalopram attenuated Aβ1-42-induced tau hyperphosphorylation in primary hippocampal neurons through the 5-HT1A receptor mediated Akt/GSK-3β pathway.

  20. Primary visual cortex volume and total neuron number are reduced in schizophrenia

    DEFF Research Database (Denmark)

    Dorph-Petersen, Karl-Anton; Pierri, Joseph H.; Wu, Qiang

    2007-01-01

    with schizophrenia reported an increased density of neurons in the primary visual cortex (Brodmann's area 17, BA17). The observed changes in visual processing may thus be reflected in structural changes in the circuitry of BA17. To characterize the structural changes further we used stereological methods based...... on unbiased principles of sampling (Cavalieri's principle and the optical fractionator) to estimate the total volume and neuron number of BA17 in postmortem brains from 10 subjects with schizophrenia and 10 matched normal comparison subjects. In addition, we assessed cortical thickness. We found a marked...... and significant reduction in total neuron number (25%) and volume (22%) of BA17 in the schizophrenia group relative to the normal comparison subjects. In contrast, we found no changes in neuronal density or cortical thickness between the two groups. Subjects with schizophrenia therefore have a smaller cortical...

  1. HeyL Regulates the Number of TrkC Neurons in Dorsal Root Ganglia

    OpenAIRE

    Mukhopadhyay, Abhishek; Jarrett, Jennifer; Chlon, Timothy; Kessler, John A

    2009-01-01

    The basic-helix-loop-helix transcription factor HeyL is expressed at high levels by neural crest progenitor cells (NCPs) that give rise to neurons and glia in dorsal root ganglia (DRG). Since HeyL expression was observed in these NCPs during the period of neurogenesis, we generated HeyL null mutants to help examine the factor’s role in ganglion neuronal specification. Homozygous null mutation of HeyL reduced the number of TrkC+ neurons in DRG at birth including the subpopulation that expresse...

  2. Updating stored memory requires adult hippocampal neurogenesis

    OpenAIRE

    Suárez-Pereira, Irene; Carrión, Ángel M

    2015-01-01

    Adult hippocampal neurogenesis appears to influence hippocampal functions, such as memory formation for example. While adult hippocampal neurogenesis is known to be involved in hippocampal-dependent learning and consolidation processes, the role of such immature neurons in memory reconsolidation, a process involved in the modification of stored memories, remains unclear. Here, using a novel fast X-ray ablation protocol to deplete neurogenic cells, we have found that adult hippocampal neurogen...

  3. 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.

  4. 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

  5. Stereological analysis of neuron, glial and endothelial cell numbers in the human amygdaloid complex.

    Science.gov (United States)

    García-Amado, María; Prensa, Lucía

    2012-01-01

    Cell number alterations in the amygdaloid complex (AC) might coincide with neurological and psychiatric pathologies with anxiety imbalances as well as with changes in brain functionality during aging. This stereological study focused on estimating, in samples from 7 control individuals aged 20 to 75 years old, the number and density of neurons, glia and endothelial cells in the entire AC and in its 5 nuclear groups (including the basolateral (BL), corticomedial and central groups), 5 nuclei and 13 nuclear subdivisions. The volume and total cell number in these territories were determined on Nissl-stained sections with the Cavalieri principle and the optical fractionator. The AC mean volume was 956 mm(3) and mean cell numbers (x10(6)) were: 15.3 neurons, 60 glial cells and 16.8 endothelial cells. The numbers of endothelial cells and neurons were similar in each AC region and were one fourth the number of glial cells. Analysis of the influence of the individuals' age at death on volume, cell number and density in each of these 24 AC regions suggested that aging does not affect regional size or the amount of glial cells, but that neuron and endothelial cell numbers respectively tended to decrease and increase in territories such as AC or BL. These accurate stereological measures of volume and total cell numbers and densities in the AC of control individuals could serve as appropriate reference values to evaluate subtle alterations in this structure in pathological conditions.

  6. Stereological analysis of neuron, glial and endothelial cell numbers in the human amygdaloid complex.

    Directory of Open Access Journals (Sweden)

    María García-Amado

    Full Text Available Cell number alterations in the amygdaloid complex (AC might coincide with neurological and psychiatric pathologies with anxiety imbalances as well as with changes in brain functionality during aging. This stereological study focused on estimating, in samples from 7 control individuals aged 20 to 75 years old, the number and density of neurons, glia and endothelial cells in the entire AC and in its 5 nuclear groups (including the basolateral (BL, corticomedial and central groups, 5 nuclei and 13 nuclear subdivisions. The volume and total cell number in these territories were determined on Nissl-stained sections with the Cavalieri principle and the optical fractionator. The AC mean volume was 956 mm(3 and mean cell numbers (x10(6 were: 15.3 neurons, 60 glial cells and 16.8 endothelial cells. The numbers of endothelial cells and neurons were similar in each AC region and were one fourth the number of glial cells. Analysis of the influence of the individuals' age at death on volume, cell number and density in each of these 24 AC regions suggested that aging does not affect regional size or the amount of glial cells, but that neuron and endothelial cell numbers respectively tended to decrease and increase in territories such as AC or BL. These accurate stereological measures of volume and total cell numbers and densities in the AC of control individuals could serve as appropriate reference values to evaluate subtle alterations in this structure in pathological conditions.

  7. Metabolic constraint imposes tradeoff between body size and number of brain neurons in human evolution

    OpenAIRE

    Fonseca-Azevedo, Karina; Herculano-Houzel, Suzana

    2012-01-01

    Despite a general trend for larger mammals to have larger brains, humans are the primates with the largest brain and number of neurons, but not the largest body mass. Why are great apes, the largest primates, not also those endowed with the largest brains? Recently, we showed that the energetic cost of the brain is a linear function of its numbers of neurons. Here we show that metabolic limitations that result from the number of hours available for feeding and the low caloric yield of raw foo...

  8. The Protective Effect of Icariin on Mitochondrial Transport and Distribution in Primary Hippocampal Neurons from 3× Tg-AD Mice.

    Science.gov (United States)

    Chen, Yijing; Han, Shuangxue; Huang, Xiuxian; Ni, Jiazuan; He, Xiaoyang

    2016-01-27

    Icariin, a pharmacologically active component isolated from the Chinese herb Epimedium, has been shown to improve spatial learning and memory abilities in Alzheimer's disease (AD) rats through inhibition of Aβ production and tau protein hyperphosphorylation. However, the potential mechanism of icariin-induced protective effects against mitochondrial dysfunctions in AD still remains unclear. In the present study, we investigated the effect of icariin on the modulation of mitochondrial transport and distribution in primary hippocampal cultures from triple-transgenic (3× Tg) AD mice. The results showed that icariin enhanced mitochondrial motility and increased mitochondrial index and mitochondrial length and size in the diseased neurons. Additionally, the expression of the key mitochondrial enzyme, pyruvate dehydrogenase-E1α (PDHE1α), and the post synaptic density protein 95 (PSD95), was preserved in AD neurons after icariin treatment, accompanied by a downregulation of Aβ and phosphorylated tau expression in the corresponding areas. Further study showed that icariin treatment resulted in a decrease in mitochondrial fission protein dynamin-related protein 1 (Drp1) and an increase in fusion protein Mitofusin 2 (Mfn2). These data indicate that icariin can promote mitochondrial transport, protect mitochondria against fragmentation and preserve the expression of mitochondrial and synaptic functional proteins in AD neurons. Thus, icariin may be a potential therapeutic complement for AD and other mitochondrial malfunction-related neuronal degenerative diseases.

  9. The Protective Effect of Icariin on Mitochondrial Transport and Distribution in Primary Hippocampal Neurons from 3× Tg-AD Mice

    Directory of Open Access Journals (Sweden)

    Yijing Chen

    2016-01-01

    Full Text Available Icariin, a pharmacologically active component isolated from the Chinese herb Epimedium, has been shown to improve spatial learning and memory abilities in Alzheimer’s disease (AD rats through inhibition of Aβ production and tau protein hyperphosphorylation. However, the potential mechanism of icariin-induced protective effects against mitochondrial dysfunctions in AD still remains unclear. In the present study, we investigated the effect of icariin on the modulation of mitochondrial transport and distribution in primary hippocampal cultures from triple-transgenic (3× Tg AD mice. The results showed that icariin enhanced mitochondrial motility and increased mitochondrial index and mitochondrial length and size in the diseased neurons. Additionally, the expression of the key mitochondrial enzyme, pyruvate dehydrogenase-E1α (PDHE1α, and the post synaptic density protein 95 (PSD95, was preserved in AD neurons after icariin treatment, accompanied by a downregulation of Aβ and phosphorylated tau expression in the corresponding areas. Further study showed that icariin treatment resulted in a decrease in mitochondrial fission protein dynamin-related protein 1 (Drp1 and an increase in fusion protein Mitofusin 2 (Mfn2. These data indicate that icariin can promote mitochondrial transport, protect mitochondria against fragmentation and preserve the expression of mitochondrial and synaptic functional proteins in AD neurons. Thus, icariin may be a potential therapeutic complement for AD and other mitochondrial malfunction-related neuronal degenerative diseases.

  10. Dissociation between two subgroups of the suprachiasmatic nucleus affected by the number of damped oscillated neurons

    Science.gov (United States)

    Gu, Changgui; Yang, Huijie; Rohling, Jos HT

    2017-03-01

    In mammals, the main clock located in the suprachiasmatic nucleus (SCN) of the brain synchronizes the body rhythms to the environmental light-dark cycle. The SCN is composed of about 2 ×104 neurons which can be classified into three oscillatory phenotypes: self-sustained oscillators, damped oscillators, and arrhythmic neurons. Exposed to an artificial external light-dark cycle with a period of 22 h instead of 24 h , two subgroups of the SCN can become desynchronized (dissociated). The ventrolateral (VL) subgroup receives photic input and is entrained to the external cycle and a dorsomedial (DM) subgroup oscillates with its endogenous (i.e., free running) period and is synchronized to the external light-dark cycle through coupling from the VL. In the present study, we examined the effects of damped oscillatory neurons on the dissociation between VL and DM under an external 22 h cycle. We found that, with increasing numbers of damped oscillatory neurons located in the VL, the dissociation between the VL and DM emerges, but if these neurons are increasingly present in the DM the dissociation disappears. Hence, the damped oscillatory neurons in different subregions of the SCN play distinct roles in the dissociation between the two subregions of the SCN. This shows that synchrony between SCN subregions is affected by the number of damped oscillatory neurons and the location of these cells. We suggest that more knowledge on the number and the location of these cells may explain why some species do show a dissociation between the subregions and others do not, as the distribution of oscillatory types of neurons offers a plausible and novel candidate mechanism to explain heterogeneity.

  11. Ischemic preconditioning protects hippocampal pyramidal neurons from transient ischemic injury via the attenuation of oxidative damage through upregulating heme oxygenase-1.

    Science.gov (United States)

    Lee, Jae-Chul; Kim, In Hye; Park, Joon Ha; Ahn, Ji Hyeon; Cho, Jeong-Hwi; Cho, Geum-Sil; Tae, Hyun-Jin; Chen, Bai Hui; Yan, Bing Chun; Yoo, Ki-Yeon; Choi, Jung Hoon; Lee, Choong Hyun; Hwang, In Koo; Cho, Jun Hwi; Kwon, Young-Guen; Kim, Young-Myeong; Won, Moo-Ho

    2015-02-01

    Ischemic preconditioning (IPC) provides neuroprotection against subsequent severe ischemic injury by activating specific mechanisms. In this study, we tested the hypothesis that IPC attenuates postischemic neuronal death via heme oxygenase-1 (HO-1). Animals used in this study were randomly assigned to 4 groups; sham-operated group, ischemia-operated group, IPC plus (+) sham-operated group and IPC+ischemia-operated group. IPC was induced by subjecting gerbils to 2min of ischemia followed by 1 day of recovery. A significant loss of neurons was observed in pyramidal neurons of the hippocampal CA1 region (CA1) in the ischemia-operated groups at 5 days postischemia. In the IPC+ischemia-operated groups, CA1 pyramidal neurons were well protected. The level of HO-1 protein and its activity increased significantly in the CA1 of the IPC+sham-operated group, and the level and activity was maintained in all the time after ischemia-reperfusion compared with the ischemia-operated groups. HO-1 immunoreactivity was induced in the CA1 pyramidal neurons in both IPC+sham-operated- and IPC+ischemia-operated groups. We also found that levels or immunoreactivities of superoxide anion, 8-hydroxy-2'-deoxyguanosine and 4-hydroxy-2-nonenal were significantly decreased in the CA1 of both IPC+sham-operated- and IPC+ischemia-operated groups. Whereas, treatment with zinc protoporphyrin IX (a HO-1 inhibitor) into the IPC+ischemia-operated groups did not preserve the IPC-mediated increase of HO-1 and lost beneficial effects of IPC by inhibiting ischemia-induced DNA damage and lipid peroxidation. In brief, IPC protects CA1 pyramidal neurons from ischemic injury by upregulating HO-1, and we suggest that the enhancement of HO-1 expression by IPC may be a legitimate strategy for a therapeutic intervention of cerebral ischemic damage. Copyright © 2014 Elsevier Inc. All rights reserved.

  12. Rapid generation of mitochondrial superoxide induces mitochondrion-dependent but caspase-independent cell death in hippocampal neuronal cells that morphologically resembles necroptosis

    Energy Technology Data Exchange (ETDEWEB)

    Fukui, Masayuki; Choi, Hye Joung; Zhu, Bao Ting, E-mail: BTZhu@kumc.edu

    2012-07-15

    Studies in recent years have revealed that excess mitochondrial superoxide production is an important etiological factor in neurodegenerative diseases, resulting from oxidative modifications of cellular lipids, proteins, and nucleic acids. Hence, it is important to understand the mechanism by which mitochondrial oxidative stress causes neuronal death. In this study, the immortalized mouse hippocampal neuronal cells (HT22) in culture were used as a model and they were exposed to menadione (also known as vitamin K{sub 3}) to increase intracellular superoxide production. We found that menadione causes preferential accumulation of superoxide in the mitochondria of these cells, along with the rapid development of mitochondrial dysfunction and cellular ATP depletion. Neuronal death induced by menadione is independent of the activation of the MAPK signaling pathways and caspases. The lack of caspase activation is due to the rapid depletion of cellular ATP. It was observed that two ATP-independent mitochondrial nucleases, namely, AIF and Endo G, are released following menadione exposure. Silencing of their expression using specific siRNAs results in transient suppression (for ∼ 12 h) of mitochondrial superoxide-induced neuronal death. While suppression of the mitochondrial superoxide dismutase expression markedly sensitizes neuronal cells to mitochondrial superoxide-induced cytotoxicity, its over-expression confers strong protection. Collectively, these findings showed that many of the observed features associated with mitochondrial superoxide-induced cell death, including caspase independency, rapid depletion of ATP level, mitochondrial release of AIF and Endo G, and mitochondrial swelling, are distinctly different from those of apoptosis; instead they resemble some of the known features of necroptosis. -- Highlights: ► Menadione causes mitochondrial superoxide accumulation and injury. ► Menadione-induced cell death is caspase-independent, due to rapid depletion of

  13. Volatile anesthetic isoflurane inhibits LTP induction of hippocampal CA1 neurons through α4β2 nAChR subtype-mediated mechanisms.

    Science.gov (United States)

    Piao, M-H; Liu, Y; Wang, Y-S; Qiu, J-P; Feng, C-S

    2013-10-01

    Volatile anesthetic isoflurane contributes to postoperative cognitive dysfunction and inhibition of long-term potentiation (LTP), a synaptic model of learning and memory, but the mechanisms are uncertain. Central neuronal α4β2 subtype nicotinic acetylcholine receptors (nAChRs) are involved in the induction of LTP in the hippocampus. Isoflurane inhibits α4β2 nAChRs at concentrations lower than those used for anesthesia. Therefore, we hypothesized that isoflurane-inhibited LTP induction of hippocampal CA1 neurons via α4β2 nAChRs subtype inhibition. Transverse hippocampal slices (400μm thick) were obtained from male rats (6-8 weeks old). Population spikes were evoked using extracellular electrodes by electrical stimulation of the Schaffer collateral-commissural pathway of rat hippocampal slices. LTP was induced using high frequency stimulation (HFS; 100Hz, 1s). Clinically relevant concentrations (0.125-0.5mM) of isoflurane with or without nicotine (nAChRs agonist), mecamylamine (nAChRs antagonist), 3-[2(S)-2-azetidinylmethoxy] pyridine (A85380) and epibatidine (α4β2 nAChRs agonist), dihydro β erythroidine (DHβE) (α4β2 nAChRs antagonist) were added to the perfusion solution 20min before HFS to test their effects on LTP by HFS respectively. A brief HFS induced stable LTP in rat hippocampal slices, but LTP was significantly inhibited in the presence of isoflurane at concentrations of 0.125-0.5mM. The inhibitive effect of isoflurane on LTP was not only reversible and could be prevented by nAChRs agonist nicotine and α4β2 nAChRs agonist A85380 and epibatidine, but also mimicked and potentiated by nAChRs antagonist mecamylamine and α4β2 nAChRs antagonist DHβE. Inhibition of α4β2 nAChRs subtype of hippocampus participates in isoflurane-mediated LTP inhibition. Copyright © 2013 Société française d’anesthésie et de réanimation (Sfar). Published by Elsevier SAS. All rights reserved.

  14. No relative expansion of the number of prefrontal neurons in primate and human evolution.

    Science.gov (United States)

    Gabi, Mariana; Neves, Kleber; Masseron, Carolinne; Ribeiro, Pedro F M; Ventura-Antunes, Lissa; Torres, Laila; Mota, Bruno; Kaas, Jon H; Herculano-Houzel, Suzana

    2016-08-23

    Human evolution is widely thought to have involved a particular expansion of prefrontal cortex. This popular notion has recently been challenged, although controversies remain. Here we show that the prefrontal region of both human and nonhuman primates holds about 8% of cortical neurons, with no clear difference across humans and other primates in the distribution of cortical neurons or white matter cells along the anteroposterior axis. Further, we find that the volumes of human prefrontal gray and white matter match the expected volumes for the number of neurons in the gray matter and for the number of other cells in the white matter compared with other primate species. These results indicate that prefrontal cortical expansion in human evolution happened along the same allometric trajectory as for other primate species, without modification of the distribution of neurons across its surface or of the volume of the underlying white matter. We thus propose that the most distinctive feature of the human prefrontal cortex is its absolute number of neurons, not its relative volume.

  15. Taurine increases hippocampal neurogenesis in aging mice

    Directory of Open Access Journals (Sweden)

    Elias Gebara

    2015-05-01

    Full Text Available Aging is associated with increased inflammation and reduced hippocampal neurogenesis, which may in turn contribute to cognitive impairment. Taurine is a free amino acid found in numerous diets, with anti-inflammatory properties. Although abundant in the young brain, the decrease in taurine concentration with age may underlie reduced neurogenesis. Here, we assessed the effect of taurine on hippocampal neurogenesis in middle-aged mice. We found that taurine increased cell proliferation in the dentate gyrus through the activation of quiescent stem cells, resulting in increased number of stem cells and intermediate neural progenitors. Taurine had a direct effect on stem/progenitor cells proliferation, as observed in vitro, and also reduced activated microglia. Furthermore, taurine increased the survival of newborn neurons, resulting in a net increase in adult neurogenesis. Together, these results show that taurine increases several steps of adult neurogenesis and support a beneficial role of taurine on hippocampal neurogenesis in the context of brain aging.

  16. Quantifying the behavioural relevance of hippocampal neurogenesis

    National Research Council Canada - National Science Library

    Lazic, Stanley E; Fuss, Johannes; Gass, Peter

    2014-01-01

    .... A systematic review of the literature was conducted and the data reanalysed using causal mediation analysis, which can estimate the behavioural contribution of new hippocampal neurons separately...

  17. Reduced number of axonal mitochondria and tau hypophosphorylation in mouse P301L tau knockin neurons.

    Science.gov (United States)

    Rodríguez-Martín, Teresa; Pooler, Amy M; Lau, Dawn H W; Mórotz, Gábor M; De Vos, Kurt J; Gilley, Jonathan; Coleman, Michael P; Hanger, Diane P

    2016-01-01

    Expression of the frontotemporal dementia-related tau mutation, P301L, at physiological levels in adult mouse brain (KI-P301L mice) results in overt hypophosphorylation of tau and age-dependent alterations in axonal mitochondrial transport in peripheral nerves. To determine the effects of P301L tau expression in the central nervous system, we examined the kinetics of mitochondrial axonal transport and tau phosphorylation in primary cortical neurons from P301L knock-in (KI-P301L) mice. We observed a significant 50% reduction in the number of mitochondria in the axons of cortical neurons cultured from KI-P301L mice compared to wild-type neurons. Expression of murine P301L tau did not change the speed, direction of travel or likelihood of movement of mitochondria. Notably, the angle that defines the orientation of the mitochondria in the axon, and the volume of individual moving mitochondria, were significantly increased in neurons expressing P301L tau. We found that murine tau phosphorylation in KI-P301L mouse neurons was diminished and the ability of P301L tau to bind to microtubules was also reduced compared to tau in wild-type neurons. The P301L mutation did not influence the ability of murine tau to associate with membranes in cortical neurons or in adult mouse brain. We conclude that P301L tau is associated with mitochondrial changes and causes an early reduction in murine tau phosphorylation in neurons coupled with impaired microtubule binding of tau. These results support the association of mutant tau with detrimental effects on mitochondria and will be of significance for the pathogenesis of tauopathies. Crown Copyright © 2015. Published by Elsevier Inc. All rights reserved.

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

    Directory of Open Access Journals (Sweden)

    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.

  19. Intermittent fasting promotes prolonged associative interactions during synaptic tagging/capture by altering the metaplastic properties of the CA1 hippocampal neurons.

    Science.gov (United States)

    Dasgupta, Ananya; Kim, Joonki; Manakkadan, Anoop; Arumugam, Thiruma V; Sajikumar, Sreedharan

    2017-12-19

    Metaplasticity is the inherent property of a neuron or neuronal population to undergo activity-dependent changes in neural function that modulate subsequent synaptic plasticity. Here we studied the effect of intermittent fasting (IF) in governing the interactions of associative plasticity mechanisms in the pyramidal neurons of rat hippocampal area CA1. Late long-term potentiation and its associative mechanisms such as synaptic tagging and capture at an interval of 120 min were evaluated in four groups of animals, AL (Ad libitum), IF12 (daily IF for 12 h), IF16 (daily IF for 16 h) and EOD (every other day IF for 24 h). IF had no visible effect on the early or late plasticity but it manifested a critical role in prolonging the associative interactions between weak and strong synapses at an interval of 120 min in IF16 and EOD animals. However, both IF12 and AL did not show associativity at 120 min. Plasticity genes such as Bdnf and Prkcz, which are well known for their expressions in late plasticity and synaptic tagging and capture, were significantly upregulated in IF16 and EOD in comparison to AL. Specific inhibition of brain derived neurotropic factor (BDNF) prevented the prolonged associativity expressed in EOD. Thus, daily IF for 16 h or more can be considered to enhance the metaplastic properties of synapses by improving their associative interactions that might translate into animprovedmemoryformation. Copyright © 2017. Published by Elsevier Inc.

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

    Science.gov (United States)

    Korol, Sergiy V.; Jin, Zhe; Birnir, Bryndis

    2015-01-01

    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. PMID:25927918

  1. Enhancement of information transmission of sub-threshold signals applied to distal positions of dendritic trees in hippocampal CA1 neuron models with stochastic resonance.

    Science.gov (United States)

    Mino, Hiroyuki; Durand, Dominique M

    2010-09-01

    Stochastic resonance (SR) has been shown to enhance the signal-to-noise ratio and detection of low level signals in neurons. It is not yet clear how this effect of SR plays an important role in the information processing of neural networks. The objective of this article is to test the hypothesis that information transmission can be enhanced with SR when sub-threshold signals are applied to distal positions of the dendrites of hippocampal CA1 neuron models. In the computer simulation, random sub-threshold signals were presented repeatedly to a distal position of the main apical branch, while the homogeneous Poisson shot noise was applied as a background noise to the mid-point of a basal dendrite in the CA1 neuron model consisting of the soma with one sodium, one calcium, and five potassium channels. From spike firing times recorded at the soma, the mutual information and information rate of the spike trains were estimated. The simulation results obtained showed a typical resonance curve of SR, and that as the activity (intensity) of sub-threshold signals increased, the maximum value of the information rate tended to increased and eventually SR disappeared. It is concluded that SR can play a key role in enhancing the information transmission of sub-threshold stimuli applied to distal positions on the dendritic trees.

  2. Influence of the on-line ELF-EMF stimulation on the electrophysiological properties of the rat hippocampal CA1 neurons in vitro

    Science.gov (United States)

    Zheng, Yu; Ma, Wei; Dong, Lei; Dou, Jun-rong; Gao, Yang; Xue, Jing

    2017-10-01

    The extremely low frequency electromagnetic fields (ELF-EMFs) have been shown to have an environmentally negative effect on humans' health; however, its treatment effect is beneficial for patients suffering from neurological disorders. Despite this success, the application of ELF-EMF has exceeded in the understanding of its internal mechanism. Recently, it was found that on-line magnetic stimulation may offer advantages over off-line magnetic exposure and has proven to be effective in activating the prefrontal cortex pyramidal neurons in vitro. Here, we perform computational simulations of the stimulation coils in COMSOL modeling to describe the uniformity of the distribution of the on-line magnetic field. Interestingly, the modeling data and actual measurements showed that the densities of the magnetic flux that was generated by the on-line stimulation coils were similar. The on-line magnetic stimulator induced sodium channel currents as well as field excitatory postsynaptic potentials of the rat hippocampal CA1 neurons and successfully demonstrated its extensive applications to activate neuronal tissue. These findings further raise the possibility that the instrument of on-line magnetic stimulation may be an effective alternative for studies in the field of bioelectromagnetics.

  3. Photolysis of Postsynaptic Caged Ca2+ Can Potentiate and Depress Mossy Fiber Synaptic Responses in Rat Hippocampal CA3 Pyramidal Neurons

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    Wang, Jun; Yeckel, Mark F.; Johnston, Daniel; Zucker, Robert S.

    2010-01-01

    The induction of mossy fiber-CA3 long-term potentiation (LTP) and depression (LTD) has been variously described as being dependent on either pre- or postsynaptic factors. Some of the postsynaptic factors for LTP induction include ephrin-B receptor tyrosine kinases and a rise in postsynaptic Ca2+ ([Ca2+]i). Ca2+ is also believed to be involved in the induction of the various forms of LTD at this synapse. We used photolysis of caged Ca2+ compounds to test whether a postsynaptic rise in [Ca2+]i is sufficient to induce changes in synaptic transmission at mossy fiber synapses onto rat hippocampal CA3 pyramidal neurons. We were able to elevate postsynaptic [Ca2+]i to approximately 1 μm for a few seconds in pyramidal cell somata and dendrites. We estimate that CA3 pyramidal neurons have approximately fivefold greater endogenous Ca2+ buffer capacity than CA1 neurons, limiting the rise in [Ca2+]i achievable by photolysis. This [Ca2+]i rise induced either a potentiation or a depression at mossy fiber synapses in different preparations. Neither the potentiation nor the depression was accompanied by consistent changes in paired-pulse facilitation, suggesting that these forms of plasticity may be distinct from synaptically induced LTP and LTD at this synapse. Our results are consistent with a postsynaptic locus for the induction of at least some forms of synaptic plasticity at mossy fiber synapses. PMID:14645386

  4. Gender and age related changes in number of dopaminergic neurons in adult human olfactory bulb.

    Science.gov (United States)

    Alizadeh, Rafieh; Hassanzadeh, Gholamreza; Soleimani, Mansoureh; Joghataei, Mohammad Taghi; Siavashi, Vahid; Khorgami, Zhinoos; Hadjighassem, Mahmoudreza

    2015-11-01

    Dopamine is one of the major brain neurotransmitters, and the loss of dopaminergic neurons in basal ganglia cause motor deficits in Parkinson's disease. We proposed that the difficulty in olfaction observed in the elderly may be due to an alteration in the number of dopaminergic neurons. Sections were taken from olfactory bulbs of post-mortem tissue specimens of 13 humans, males and females, aged from 19 to 63 years (≤35 and ≥50 years), with no history of neurological disorders. The tissues were fixed, embedded, cut on a freezing microtome, and prepared for immunohistochemical analysis using tyrosine hydroxylase (TH) and aromatic l-amino acid decarboxylase (AADC) antibodies. The number of positive neurons was counted. TH- and AADC-positive cells were present in the glomerular layer. There was no significant difference between the numbers of TH- and AADC-positive cells, in males and females, and in young and elderly individuals. The quantitative analysis revealed that the number of TH- and AADC-positive neurons were significantly higher in males than in females (Polfactory bulbs of the elderly compared with young individuals (Polfactory performance. Moreover, the increase in dopaminergic cells in the olfactory bulb of the elderly may indicate the existence of rostral migratory stream in adult humans. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Decreased number of oxytocin neurons in the paraventricular nucleus of the human hypothalamus in AIDS.

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    Purba, J S; Hofman, M A; Portegies, P; Troost, D; Swaab, D F

    1993-08-01

    The number of immunocytochemically identified vasopressin (AVP) and oxytocin (OXT) neurons was determined morphometrically in the paraventricular nucleus of the hypothalamus of 20 acquired immunodeficiency syndrome (AIDS) patients and 10 controls. The AIDS group consisted of 14 homosexual males (age range 25-62 years), four of whom had a probable HIV-1 associated dementia complex, and six non-demented heterosexuals (four males and two females, age range 21-73 years). Ten males without a primary neurological or psychiatric disease served as a control group. The number of OXT-expressing neurons in the paraventricular nucleus of both groups of AIDS patients was approximately 40% lower than that of the controls. In contrast, the three groups showed no significant differences in the number of AVP-expressing neurons in the paraventricular nucleus. Since there were no significant differences in the number of AVP and OXT cells between the homosexual and heterosexual subjects with AIDS, the morphological difference in the paraventricular nucleus seems to be related to AIDS and not to sexual orientation. No inflammatory changes were found in the paraventricular nucleus area. The selective changes in the OXT neurons of the paraventricular nucleus may be the basis for part of the neuroendocrine, autonomic dysfunction or vegetative symptoms in AIDS.

  6. Regulation of Cerebral Cortical Size and Neuron Number by Fibroblast Growth Factors: Implications for Autism

    Science.gov (United States)

    Vaccarino, Flora M.; Grigorenko, Elena L.; Smith, Karen Muller; Stevens, Hanna E.

    2009-01-01

    Increased brain size is common in children with autism spectrum disorders. Here we propose that an increased number of cortical excitatory neurons may underlie the increased brain volume, minicolumn pathology and excessive network excitability, leading to sensory hyper-reactivity and seizures, which are often found in autism. We suggest that…

  7. LAMP-2 deficiency leads to hippocampal dysfunction but normal clearance of neuronal substrates of chaperone-mediated autophagy in a mouse model for Danon disease.

    Science.gov (United States)

    Rothaug, Michelle; Stroobants, Stijn; Schweizer, Michaela; Peters, Judith; Zunke, Friederike; Allerding, Mirka; D'Hooge, Rudi; Saftig, Paul; Blanz, Judith

    2015-01-31

    The Lysosomal Associated Membrane Protein type-2 (LAMP-2) is an abundant lysosomal membrane protein with an important role in immunity, macroautophagy (MA) and chaperone-mediated autophagy (CMA). Mutations within the Lamp2 gene cause Danon disease, an X-linked lysosomal storage disorder characterized by (cardio)myopathy and intellectual dysfunction. The pathological hallmark of this disease is an accumulation of glycogen and autophagic vacuoles in cardiac and skeletal muscle that, along with the myopathy, is also present in LAMP-2-deficient mice. Intellectual dysfunction observed in the human disease suggests a pivotal role of LAMP-2 within brain. LAMP-2A, one specific LAMP-2 isoform, was proposed to be important for the lysosomal degradation of selective proteins involved in neurodegenerative diseases such as Huntington's and Parkinson's disease. To elucidate the neuronal function of LAMP-2 we analyzed knockout mice for neuropathological changes, MA and steady-state levels of CMA substrates. The absence of LAMP-2 in murine brain led to inflammation and abnormal behavior, including motor deficits and impaired learning. The latter abnormality points to hippocampal dysfunction caused by altered lysosomal activity, distinct accumulation of p62-positive aggregates, autophagic vacuoles and lipid storage within hippocampal neurons and their presynaptic terminals. The absence of LAMP-2 did not apparently affect MA or steady-state levels of selected CMA substrates in brain or neuroblastoma cells under physiological and prolonged starvation conditions. Our data contribute to the understanding of intellectual dysfunction observed in Danon disease patients and highlight the role of LAMP-2 within the central nervous system, particularly the hippocampus.

  8. Spine formation pattern of adult-born neurons is differentially modulated by the induction timing and location of hippocampal plasticity.

    Directory of Open Access Journals (Sweden)

    Noriaki Ohkawa

    Full Text Available In the adult hippocampus dentate gyrus (DG, newly born neurons are functionally integrated into existing circuits and play important roles in hippocampus-dependent memory. However, it remains unclear how neural plasticity regulates the integration pattern of new neurons into preexisting circuits. Because dendritic spines are major postsynaptic sites for excitatory inputs, spines of new neurons were visualized by retrovirus-mediated labeling to evaluate integration. Long-term potentiation (LTP was induced at 12, 16, or 21 days postinfection (dpi, at which time new neurons have no, few, or many spines, respectively. The spine expression patterns were investigated at one or two weeks after LTP induction. Induction at 12 dpi increased later spinogenesis, although the new neurons at 12 dpi didn't respond to the stimulus for LTP induction. Induction at 21 dpi transiently mediated spine enlargement. Surprisingly, LTP induction at 16 dpi reduced the spine density of new neurons. All LTP-mediated changes specifically appeared within the LTP-induced layer. Therefore, neural plasticity differentially regulates the integration of new neurons into the activated circuit, dependent on their developmental stage. Consequently, new neurons at different developmental stages may play distinct roles in processing the acquired information by modulating the connectivity of activated circuits via their integration.

  9. A lentiviral sponge for miR-101 regulates RanBP9 expression and amyloid precursor protein metabolism in hippocampal neurons

    Directory of Open Access Journals (Sweden)

    Christian eBarbato

    2014-02-01

    Full Text Available Neurodegeneration associated with amyloid β (Aβ peptide accumulation, synaptic loss, and memory impairment are pathophysiological features of Alzheimer's disease (AD. Numerous microRNAs regulate amyloid precursor protein (APP expression and metabolism. We previously reported that miR-101 is a negative regulator of APP expression in cultured hippocampal neurons. In this study, a search for predicted APP metabolism-associated miR-101 targets led to the identification of a conserved miR-101 binding site within the 3’ untranslated region (UTR of the mRNA encoding Ran-binding protein 9 (RanBP9. RanBP9 increases APP processing by β-amyloid converting enzyme 1 (BACE1, secretion of soluble APPβ (sAPPβ, and generation of Aβ. MiR-101 significantly reduced reporter gene expression when co-transfected with a RanBP9 3'-UTR reporter construct, while site-directed mutagenesis of the predicted miR-101 target site eliminated the reporter response. To investigate the effect of stable inhibition of miR-101 both in vitro and in vivo, a microRNA sponge was developed to bind miR-101 and derepress its targets. Four tandem bulged miR-101 responsive elements (REs, located downstream of the enhanced green fluorescence protein (EGFP open reading frame and driven by the synapsin promoter, were placed in a lentiviral vector to create the pLSyn-miR-101 sponge. Delivery of the sponge to primary hippocampal neurons significantly increased both APP and RanBP9 expression, as well as sAPPβ levels in the conditioned medium. Importantly, silencing of endogenous RanBP9 reduced sAPPβ levels in miR-101 sponge-containing hippocampal cultures, indicating that miR-101 inhibition may increase amyloidogenic processing of APP by RanBP9. Lastly, the impact of miR-101 on its targets was demonstrated in vivo by intrahippocampal injection of the pLSyn-miR-101 sponge into C57BL6 mice. This study thus provides the basis for studying the consequences of long-term miR-101 inhibition on

  10. Estradiol attenuates ischemia-induced death of hippocampal neurons and enhances synaptic transmission in aged, long-term hormone-deprived female rats.

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    Tomoko Inagaki

    Full Text Available Transient global forebrain ischemia causes selective, delayed death of hippocampal CA1 pyramidal neurons, and the ovarian hormone 17β-estradiol (E2 reduces neuronal loss in young and middle-aged females. The neuroprotective efficacy of E2 after a prolonged period of hormone deprivation is controversial, and few studies examine this issue in aged animals given E2 treatment after induction of ischemia.The present study investigated the neuroprotective effects of E2 administered immediately after global ischemia in aged female rats (15-18 months after 6 months of hormone deprivation. We also used electrophysiological methods to assess whether CA1 synapses in the aging hippocampus remain responsive to E2 after prolonged hormone withdrawal. Animals were ovariohysterectomized and underwent 10 min global ischemia 6 months later. A single dose of E2 (2.25 µg infused intraventricularly after reperfusion significantly increased cell survival, with 45% of CA1 neurons surviving vs 15% in controls. Ischemia also induced moderate loss of CA3/CA4 pyramidal cells. Bath application of 1 nM E2 onto brain slices derived from non-ischemic aged females after 6 months of hormone withdrawal significantly enhanced excitatory transmission at CA1 synapses evoked by Schaffer collateral stimulation, and normal long-term potentiation (LTP was induced. The magnitude of LTP and of E2 enhancement of field excitatory postsynaptic potentials was indistinguishable from that recorded in slices from young rats.The data demonstrate that 1 acute post-ischemic infusion of E2 into the brain ventricles is neuroprotective in aged rats after 6 months of hormone deprivation; and 2 E2 enhances synaptic transmission in CA1 pyramidal neurons of aged long-term hormone deprived females. These findings provide evidence that the aging hippocampus remains responsive to E2 administered either in vivo or in vitro even after prolonged periods of hormone withdrawal.

  11. Role of the medial septum diagonal band of Broca cholinergic neurons in oestrogen-induced spine synapse formation on hippocampal CA1 pyramidal cells of female rats.

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    Lâm, Thiên-Trí; Leranth, Csaba

    2003-05-01

    Oestrogen is known to influence pyramidal cell spine synapse plasticity in the CA1 subfield of the hippocampus. Apart from direct oestrogen action on the hippocampus, oestrogen effects mediated by subcortical structures are known to be important. The purpose of this study was to investigate whether the medial septum diagonal band of Broca (MSDB) takes part in mediating oestrogen effects to the hippocampus. Special attention was given to the role of cholinergic MSDB neurons that project to the hippocampus, as a rather large population of them contains oestrogen receptors and, consequently, may be sensitive to oestrogen signals. Adult female rats were ovariectomized. Oestradiol- and cholesterol-filled cannulae (control) were implanted into the MSDB. To selectively eliminate the cholinergic population of MSDB neurons of oestrogen-treated animals, a group of rats was injected with 192 IgG-saporin (SAP) into the lateral ventricle 1 week before the cannula implant. Immunostaining with anti-choline acetyltransferase and parvalbumin (PA) showed that cholinergic but not PA-containing GABAergic neurons were substantially reduced in the MSDB of SAP rats. Comparative electron microscopic unbiased stereological analysis on the spine synapse density of CA1 area pyramidal cells was performed between all animal groups. Rats that received oestradiol-filled cannulae showed a higher (30%) spine synapse density than control animals. Oestrogen-treated rats that had received SAP treatment showed no significant difference to controls. Thus, this observation indicates that septo-hippocampal cholinergic neurons are involved in mediating oestrogen effects to the hippocampus. The relevance of this observation to mnemonic functions and Alzheimer's disease is discussed.

  12. Progesterone increases dopamine neurone number in differentiating mouse embryonic stem cells.

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    Díaz, N F; Díaz-Martínez, N E; Velasco, I; Camacho-Arroyo, I

    2009-08-01

    Progesterone participates in the regulation of several functions in mammals, including brain differentiation and dopaminergic transmission, but the role of progesterone in dopaminergic cell differentiation is unknown. We investigated the effects of progesterone on dopaminergic differentiation of embryonic stem cells using a five-stage protocol. Cells were incubated with different progesterone concentrations during the proliferation (stage 4) or differentiation (stage 5) phases. Progesterone added at 1, 10 and 100 nm during stage 4 increased the number of dopamine neurones at stage 5 by 72%, 80% and 62%, respectively, compared to the control group. The administration of progesterone at stage 5 did not induce significant changes in the number of dopamine neurones. These actions were not mediated by the activation of intracellular progesterone receptors because RU 486 did not block the positive effects of progesterone on differentiation to dopaminergic neurones. The results obtained suggest that progesterone should prove useful with respect to producing higher proportions of dopamine neurones from embryonic stem cells in the treatment of Parkinson's disease.

  13. Ontogeny of Biochemical, Morphological and Functional Parameters of Synaptogenesis in Primary Cultures of Rat Hippocampal and Cortical Neurons

    Science.gov (United States)

    AbstractBackground: Synaptogenesis is a critical neurodevelopmental process whereby pre-and postsynaptic neurons form apposed sites of contact specialized for excitatory and inhibitory neurotransmission. Many neurodevelopmental disorders are thought to reflect altered patterns of...

  14. Grape seed proanthocyanidin extract inhibits glutamate-induced cell death through inhibition of calcium signals and nitric oxide formation in cultured rat hippocampal neurons

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    Kim Myung-Jun

    2011-08-01

    Full Text Available Abstract Background Proanthocyanidin is a polyphenolic bioflavonoid with known antioxidant activity. Some flavonoids have a modulatory effect on [Ca2+]i. Although proanthocyanidin extract from blueberries reportedly affects Ca2+ buffering capacity, there are no reports on the effects of proanthocyanidin on glutamate-induced [Ca2+]i or cell death. In the present study, the effects of grape seed proanthocyanidin extract (GSPE on glutamate-induced excitotoxicity was investigated through calcium signals and nitric oxide (NO in cultured rat hippocampal neurons. Results Pretreatment with GSPE (0.3-10 μg/ml for 5 min inhibited the [Ca2+]i increase normally induced by treatment with glutamate (100 μM for 1 min, in a concentration-dependent manner. Pretreatment with GSPE (6 μg/ml for 5 min significantly decreased the [Ca2+]i increase normally induced by two ionotropic glutamate receptor agonists, N-methyl-D-aspartate and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA. GSPE further decreased AMPA-induced response in the presence of 1 μM nimodipine. However, GSPE did not affect the 50 mM K+-induced increase in [Ca2+]i. GSPE significantly decreased the metabotropic glutamate receptor agonist (RS-3,5-Dihydroxyphenylglycine-induced increase in [Ca2+]i, but it did not affect caffeine-induced response. GSPE (0.3-6 μg/ml significantly inhibited synaptically induced [Ca2+]i spikes by 0.1 mM [Mg2+]o. In addition, pretreatment with GSPE (6 μg/ml for 5 min inhibited 0.1 mM [Mg2+]o- and glutamate-induced formation of NO. Treatment with GSPE (6 μg/ml significantly inhibited 0.1 mM [Mg2+]o- and oxygen glucose deprivation-induced neuronal cell death. Conclusions All these data suggest that GSPE inhibits 0.1 mM [Mg2+]o- and oxygen glucose deprivation-induced neurotoxicity through inhibition of calcium signals and NO formation in cultured rat hippocampal neurons.

  15. Xenon Reduces Neuronal Hippocampal Damage and Alters the Pattern of Microglial Activation after Experimental Subarachnoid Hemorrhage: A Randomized Controlled Animal Trial

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    Michael Veldeman

    2017-09-01

    Full Text Available ObjectiveThe neuroprotective properties of the noble gas xenon have already been demonstrated using a variety of injury models. Here, we examine for the first time xenon’s possible effect in attenuating early brain injury (EBI and its influence on posthemorrhagic microglial neuroinflammation in an in vivo rat model of subarachnoid hemorrhage (SAH.MethodsSprague-Dawley rats (n = 22 were randomly assigned to receive either Sham surgery (n = 9; divided into two groups or SAH induction via endovascular perforation (n = 13, divided into two groups. Of those randomized for SAH, 7 animals were postoperatively ventilated with 50 vol% oxygen/50 vol% xenon for 1 h and 6 received 50 vol% oxygen/50 vol% nitrogen (control. The animals were sacrificed 24 h after SAH. Of each animal, a cerebral coronal section (−3.60 mm from bregma was selected for assessment of histological damage 24 h after SAH. A 5-point neurohistopathological severity score was applied to assess neuronal cell damage in H&E and NeuN stained sections in a total of four predefined anatomical regions of interest. Microglial activation was evaluated by a software-assisted cell count of Iba-1 stained slices in three cortical regions of interest.ResultsA diffuse cellular damage was apparent in all regions of the ipsilateral hippocampus 24 h after SAH. Xenon-treated animals presented with a milder damage after SAH. This effect was found to be particularly pronounced in the medial regions of the hippocampus, CA3 (p = 0.040, and dentate gyrus (DG p = 0.040. However, for the CA1 and CA2 regions, there were no statistical differences in neuronal damage according to our histological scoring. A cell count of activated microglia was lower in the cortex of xenon-treated animals. This difference was especially apparent in the left piriform cortex (p = 0.017.ConclusionIn animals treated with 50 vol% xenon (for 1 h after SAH, a less pronounced neuronal damage was

  16. Synaptic activity and nuclear calcium signaling protect hippocampal neurons from death signal-associated nuclear translocation of FoxO3a induced by extrasynaptic N-methyl-D-aspartate receptors.

    Science.gov (United States)

    Dick, Oliver; Bading, Hilmar

    2010-06-18

    Synaptic activity and the generation of nuclear calcium signals promote neuronal survival through a transcription-dependent process that is not fully understood. Here we show that one mechanism of activity-induced acquired neuroprotection involves the Forkhead transcription factor, FoxO3a, which is known to induce genomic death responses upon translocation from the cytosol to the nucleus. Depletion of endogenous FoxO3a using RNA interference renders hippocampal neurons more resistant to excitotoxic cell death. Using a FoxO3a-green fluorescent protein (GFP) fusion protein to monitor in real time the localization of FoxO3a in hippocampal neurons, we found that several cell death inducing stimuli, including the stimulation of extrasynaptic N-methyl-D-aspartate receptors, growth factor withdrawal, and oxygen-glucose deprivation, caused a swift translocation of FoxO3a-GFP from the cytosol to the cell nucleus. This translocation was inhibited in hippocampal neurons that had undergone prolonged periods of synaptic activity before exposure to cell death-inducing conditions. The activity-dependent protection from death signal-induced FoxO3a-GFP nuclear translocation required synaptic N-methyl-D-aspartate receptor activation and was dependent on nuclear calcium signaling and calcium/calmodulin-dependent protein kinase IV. The modulation of nucleo-cytoplasmic shuttling of FoxO3a may represent one mechanism through which nuclear calcium-induced genomic responses affect cell death processes.

  17. Synaptic Activity and Nuclear Calcium Signaling Protect Hippocampal Neurons from Death Signal-associated Nuclear Translocation of FoxO3a Induced by Extrasynaptic N-Methyl-d-aspartate Receptors*

    Science.gov (United States)

    Dick, Oliver; Bading, Hilmar

    2010-01-01

    Synaptic activity and the generation of nuclear calcium signals promote neuronal survival through a transcription-dependent process that is not fully understood. Here we show that one mechanism of activity-induced acquired neuroprotection involves the Forkhead transcription factor, FoxO3a, which is known to induce genomic death responses upon translocation from the cytosol to the nucleus. Depletion of endogenous FoxO3a using RNA interference renders hippocampal neurons more resistant to excitotoxic cell death. Using a FoxO3a-green fluorescent protein (GFP) fusion protein to monitor in real time the localization of FoxO3a in hippocampal neurons, we found that several cell death inducing stimuli, including the stimulation of extrasynaptic N-methyl-d-aspartate receptors, growth factor withdrawal, and oxygen-glucose deprivation, caused a swift translocation of FoxO3a-GFP from the cytosol to the cell nucleus. This translocation was inhibited in hippocampal neurons that had undergone prolonged periods of synaptic activity before exposure to cell death-inducing conditions. The activity-dependent protection from death signal-induced FoxO3a-GFP nuclear translocation required synaptic N-methyl-d-aspartate receptor activation and was dependent on nuclear calcium signaling and calcium/calmodulin-dependent protein kinase IV. The modulation of nucleo-cytoplasmic shuttling of FoxO3a may represent one mechanism through which nuclear calcium-induced genomic responses affect cell death processes. PMID:20404335

  18. Three counting methods agree on cell and neuron number in chimpanzee primary visual cortex

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    Daniel James Miller

    2014-05-01

    Full Text Available Determining the cellular composition of specific brain regions is crucial to our understanding of the function of neurobiological systems. It is therefore useful to identify the extent to which different methods agree when estimating the same properties of brain circuitry. In this study, we estimated the number of neuronal and non-neuronal cells in the primary visual cortex (area 17 or V1 of both hemispheres from a single chimpanzee. Specifically, we processed samples distributed across V1 of the right hemisphere after cortex was flattened into a sheet using two variations of the isotropic fractionator cell and neuron counting method. We processed the left hemisphere as serial brain slices for stereological investigation. The goal of this study was to evaluate the agreement between these methods in the most direct manner possible by comparing estimates of cell density across one brain region of interest in a single individual. In our hands, these methods produced similar estimates of the total cellular population (approximately 1 billion as well as the number of neurons (approximately 675 million in chimpanzee V1, providing evidence that both techniques estimate the same parameters of interest. In addition, our results indicate the strengths of each distinct tissue preparation procedure, highlighting the importance of attention to anatomical detail. In summary, we found that the isotropic fractionator and the stereological optical fractionator produced concordant estimates of the cellular composition of V1, and that this result supports the conclusion that chimpanzees conform to the primate pattern of exceptionally high packing density in V1. Ultimately, our data suggest that investigators can optimize their experimental approach by using any of these counting methods to obtain reliable cell and neuron counts.

  19. Chronic Benzodiazepine-induced reduction in GABAA receptor-mediated synaptic currents in hippocampal CA1 pyramidal neurons prevented by prior nimodipine injection

    Science.gov (United States)

    Xiang, Kun; Tietz, Elizabeth I.

    2008-01-01

    One week oral flurazepam (FZP) administration in rats results in reduced GABAA receptor-mediated synaptic transmission in CA1 pyramidal neurons associated with benzodiazepine tolerance in vivo and in vitro. Since voltage-gated calcium channel (VGCC) current density is enhanced 2-fold during chronic FZP treatment, the role of L-type VGCCs in regulating benzodiazepine-induced changes in CA1 neuron GABAA receptor-mediated function was evaluated. Nimodipine (10 mg/kg, i.p.) or vehicle (0.5 % Tween 80, 2 ml/kg) was injected 1 day after ending FZP treatment and 24 hours prior to hippocampal slice preparation for measurement of mIPSC characteristics and in vitro tolerance to zolpidem. The reduction in GABAA receptor-mediated mIPSC amplitude and estimated unitary channel conductance measured 2 days after drug removal was no longer observed following prior nimodipine injection. However, the single nimodipine injection failed to prevent in vitro tolerance to zolpidem's ability to prolong mIPSC decay in FZP-treated neurons, suggesting multiple mechanisms may be involved in regulating GABAA receptor-mediated synaptic transmission following chronic FZP administration. As reported previously in recombinant receptors, nimodipine inhibited synaptic GABAA receptor currents only at high concentrations (>30 μM), significantly greater than attained in vivo (1 μM) 45 min after a single antagonist injection. Thus, the effects of nimodipine were unlikely to be related to direct effects on GABAA receptors. As with nimodipine injection, buffering intracellular free [Ca2+] with BAPTA similarly prevented the effects on GABAA receptor-mediated synaptic transmission, suggesting intracellular Ca2+ homeostasis is important to maintain GABAA receptor function. The findings further support a role for activation of L-type VGCCs, and perhaps other Ca2+-mediated signaling pathways, in the modulation of GABAA receptor synaptic function following chronic benzodiazepine administration, independent of

  20. 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.

  1. White light emitting diode suppresses proliferation and induces apoptosis in hippocampal neuron cells through mitochondrial cytochrome c oxydase-mediated IGF-1 and TNF-α pathways.

    Science.gov (United States)

    Yang, Yang; Zong, Yibo; Sun, Qinwei; Jia, Yimin; Zhao, Ruqian

    2017-12-01

    Light emitting diode (LED) light has been tested to treat traumatic brain injury, neural degenerative diseases and psychiatric disorders. Previous studies indicate that blue LED light affects cell proliferation and apoptosis in photosensitive cells and cancer cells. In this study, we demonstrate that white LED light exposure impaired proliferation and induced apoptosis in HeLa and HT-22 hippocampal neural cells, but not C2C12 cells. Furthermore, the mechanisms underlying the effect of white LED light exposure on HT-22 cells were elucidated. In HeLa and HT-22 cells, white LED light activated mitochondrial cytochrome c oxidase (Cco), in association with enhanced ATP synthase activity and elevated intracellular ATP concentration. Also, reactive oxygen species (ROS) and nitric oxide (NO) production were increased, accompanied by higher calcium concentration and lower mitochondrial membrane potential. HT-22 cells exposed to white LED light for 24h showed reduced viability, with higher apoptotic rate and a cell cycle arrest at G0/G1 phase. Concurrently, the mRNA expression and the concentration of IGF-1 were decreased, while that of TNF-α were increased, in light-exposed cells, which was supported by the luciferase activity of both gene promoters. The down-stream mitogen-activated protein kinase (MAPK), AKT/mTOR pathways were inhibited, in association with an activation of apoptotic caspase 3. N-Acetylcysteine, a ROS scavenger, protected the cells from LED light-induced cellular damage, with rescued cell viability and restored mRNA expression of IGF-1 and TNF-α. Our data demonstrate that white LED light suppresses proliferation and induces apoptosis in hippocampal neuron cells through mitochondrial Cco/ROS-mediated IGF-1 and TNF-α pathways. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Visualization of local phosphatidylcholine synthesis within hippocampal neurons using a compartmentalized culture system and imaging mass spectrometry.

    Science.gov (United States)

    Sugiyama, Eiji; Yao, Ikuko; Setou, Mitsutoshi

    2018-01-01

    Neurons extend neurites with an increased synthesis of phosphatidylcholine (PC) that is not only a membrane component but also a functional regulator with specific fatty acid composition. To analyze the local synthesis of the PC molecular species within neurons, we combined a compartmentalized culture system with matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS). We observed that a newly synthesized PC, which contains exogenously administered palmitic acid-d3, is accumulated at the cell bodies and the tips of the distal neurites. The local accumulation within distal neurites is formed by distinct metabolic activity from cell bodies, suggesting that the local extracellular composition of free fatty acid can be a key to regulate specific functions of each PC molecular species. We expect our simple method to be a starting point for more sophisticated in vitro analytical methods for unveiling detailed lipid metabolisms within neurons. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. Brain scaling in mammalian evolution as a consequence of concerted and mosaic changes in numbers of neurons and average neuronal cell size

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    Herculano-Houzel, Suzana; Manger, Paul R.; Kaas, Jon H.

    2014-01-01

    Enough species have now been subject to systematic quantitative analysis of the relationship between the morphology and cellular composition of their brain that patterns begin to emerge and shed light on the evolutionary path that led to mammalian brain diversity. Based on an analysis of the shared and clade-specific characteristics of 41 modern mammalian species in 6 clades, and in light of the phylogenetic relationships among them, here we propose that ancestral mammal brains were composed and scaled in their cellular composition like modern afrotherian and glire brains: with an addition of neurons that is accompanied by a decrease in neuronal density and very little modification in glial cell density, implying a significant increase in average neuronal cell size in larger brains, and the allocation of approximately 2 neurons in the cerebral cortex and 8 neurons in the cerebellum for every neuron allocated to the rest of brain. We also propose that in some clades the scaling of different brain structures has diverged away from the common ancestral layout through clade-specific (or clade-defining) changes in how average neuronal cell mass relates to numbers of neurons in each structure, and how numbers of neurons are differentially allocated to each structure relative to the number of neurons in the rest of brain. Thus, the evolutionary expansion of mammalian brains has involved both concerted and mosaic patterns of scaling across structures. This is, to our knowledge, the first mechanistic model that explains the generation of brains large and small in mammalian evolution, and it opens up new horizons for seeking the cellular pathways and genes involved in brain evolution. PMID:25157220

  4. Brain scaling in mammalian evolution as a consequence of concerted and mosaic changes in numbers of neurons and average neuronal cell size

    Directory of Open Access Journals (Sweden)

    Suzana eHerculano-Houzel

    2014-08-01

    Full Text Available Enough species have now been subject to systematic quantitative analysis of the relationship between the morphology and cellular composition of their brain that patterns begin to emerge and shed light on the evolutionary path that led to mammalian brain diversity. Based on an analysis of the shared and clade-specific characteristics of 41 modern mammalian species in 6 clades, and in light of the phylogenetic relationships among them, here we propose that ancestral mammal brains were composed and scaled in their cellular composition like modern afrotherian and glire brains: with an addition of neurons that is accompanied by a decrease in neuronal density and very little modification in glial cell density, implying a significant increase in average neuronal cell size in larger brains, and the allocation of approximately 2 neurons in the cerebral cortex and 8 neurons in the cerebellum for every neuron allocated to the rest of brain. We also propose that in some clades the scaling of different brain structures has diverged away from the common ancestral layout through clade-specific (or clade-defining changes in how average neuronal cell mass relates to numbers of neurons in each structure, and how numbers of neurons are differentially allocated to each structure relative to the number of neurons in the rest of brain. Thus, the evolutionary expansion of mammalian brains has involved both concerted and mosaic patterns of scaling across structures. This is, to our knowledge, the first mechanistic model that explains the generation of brains large and small in mammalian evolution, and it opens up new horizons for seeking the cellular pathways and genes involved in brain evolution.

  5. Hippocampal GABA transporter distribution in patients with temporal lobe epilepsy and hippocampal sclerosis

    NARCIS (Netherlands)

    Schijns, O.; Karaca, U.; Andrade, P.; Nijs, L. de; Kusters, B.; Peeters, A.; Dings, J.; Pannek, H.; Ebner, A.; Rijkers, K.; Hoogland, G.

    2015-01-01

    PURPOSE: To determine hippocampal expression of neuronal GABA-transporter (GAT-1) and glial GABA-transporter (GAT-3) in patients with temporal lobe epilepsy (TLE) and hippocampal sclerosis (HS). METHODS: Hippocampal sections were immunohistochemically stained for GABA-transporter 1 and

  6. [Effects of Rhodiola rosea on level of 5-hydroxytryptamine, cell proliferation and differentiation, and number of neuron in cerebral hippocampus of rats with depression induced by chronic mild stress].

    Science.gov (United States)

    Qin, Ya-jing; Zeng, Yuan-shan; Zhou, Chun-chun; Li, Yan; Zhong, Zhi-qiang

    2008-12-01

    To explore the effects of Rhodiola rosea on the level of 5-hydroxytryptamine (5-HT), cell proliferation and differentiation, and number of neuron in cerebral hippocampus of rats with depression induced by chronic mild stress. Fifty rats were divided into 5 groups: normal control, untreated, negative control, positive control and Rhodiola rosea-treated groups. There were 10 rats in each group. Except for normal control group, depression was induced in rats by chronic mild stress. The depressive rats in the other four groups were intragastrically administered with 0.5% sodium carboxymethycellulose, fluoxetine and Rhodiola rosea for 3 weeks. After the treatment, the content of 5-HT in the hippocampus was detected by high-performance liquid chromatography. The proliferating cells and differentiated cells in the hippocampus were labeled by bromodeoxyuridine (BrdU) or/and beta-tubulin III immunohistochemistry, and the number of hippocampal neurons was counted by morphometry. Compared with the normal control group, the content of 5-HT, number of BrdU positive cells, percentage of BrdU and beta-tubulin III double labeled cells and number of neurons in cerebral hippocampus in the Rhodiola rosea-treated group were increased and recovered to normal level. Rhodiola rosea may enhance the level of 5-HT and promote the proliferation and differentiation of neural stem cells in the hippocampus of the depressive rats, and may play a role in saving injured neurons of the hippocampus.

  7. Pilocarpine-induced status epilepticus and subsequent spontaneous seizures: lack of effect on the number of gonadotropin-releasing hormone-positive neurons in a mouse model of temporal lobe epilepsy.

    Science.gov (United States)

    Fawley, J A; Pouliot, W A; Dudek, F E

    2012-02-17

    Women with temporal lobe epilepsy have a higher incidence of reproductive disorders, which have been linked to alterations in the pulsatile release of gonadotropin-releasing hormone (GnRH). These experiments tested the hypothesis that the number of GnRH neurons is reduced in an animal model of temporal lobe epilepsy. The effects of pilocarpine-induced status epilepticus (SE) and the subsequent spontaneous recurrent eizures on the number of GnRH-positive neurons were studied in adult female mice. Systemic injections of pilocarpine were used to induce SE, and diazepam was administered 90 min after the first seizure. Control mice received all drugs except pilocarpine. The mice were euthanized either 1 week or 3 months after SE (i.e. after spontaneous recurrent seizures were observed). Even though the estrous cycle was disrupted after SE, and hippocampal damage was detected in both the CA1 and CA3 regions, pilocarpine-treated mice did not show a significant decrease in total or regional numbers of GnRH-immunopositive neurons. Therefore, these data do not support the hypothesis that a reduction in the number of GnRH neurons is responsible for the disruption of the estrous cycle after pilocarpine-induced epilepsy, which suggests that other mechanisms contribute to female reproductive disorders associated with chronic epilepsy. Copyright © 2011 IBRO. Published by Elsevier Ltd. All rights reserved.

  8. Sulforhodamine 101 induces long-term potentiation of intrinsic excitability and synaptic efficacy in hippocampal CA1 pyramidal neurons

    DEFF Research Database (Denmark)

    Kang, J.; Kang, N.; Yu, Y.

    2010-01-01

    Sulforhodamine 101 (SR101) has been extensively used for investigation as a specific marker for astroglia in vivo and activity-dependent dye for monitoring regulated exocytosis. Here, we report that SR101 has bioactive effects on neuronal activity. Perfusion of slices with SR101 (1 microM) for 10...

  9. Lactation-induced reduction in hippocampal neurogenesis is reversed by repeated stress exposure.

    Science.gov (United States)

    Hillerer, Katharina M; Neumann, Inga D; Couillard-Despres, Sebastien; Aigner, Ludwig; Slattery, David A

    2014-06-01

    The peripartum period is a time of high susceptibility for mood and anxiety disorders, some of which have recently been associated with alterations in hippocampal neurogenesis. Several factors including stress, aging, and, perhaps unexpectedly, lactation have been shown to decrease hippocampal neurogenesis. Intriguingly, lactation is also a time of reduced stress responsivity suggesting that the effect of stress on neurogenic processes may differ during this period. Therefore, the aim of the present study was to assess the effect of repeated stress during lactation [2 h restraint stress from lactation day (LD) 2 to LD13] on brain weight, hippocampal volume, cell proliferation and survival, and on neuronal and astroglial differentiation. In addition to confirming the known lactation-associated decrease in cell proliferation and survival, we could reveal that stress reversed the lactation-induced decrease in cell proliferation, while it did not affect survival of newly born cells, nor the number of mature neurons , nor did it alter immature neuron production or the number of astroglial cells in lactation. Stress exposure increased relative brain weight and hippocampal volume mirroring the observed changes in neurogenesis. Interestingly, hippocampal volume and relative brain weight were lower in lactation as compared to nulliparous females under nonstressed conditions. This study assessed the effect of stress during lactation on hippocampal neurogenesis and indicates that stress interferes with important peripartum adaptations at the level of the hippocampus. © 2014 Wiley Periodicals, Inc.

  10. Regulation of tyrosine kinase B activity by the Cyp46/cholesterol loss pathway in mature hippocampal neurons: relevance for neuronal survival under stress and in aging.

    Science.gov (United States)

    Sodero, Alejandro O; Trovò, Laura; Iannilli, Francesca; Van Veldhoven, Paul; Dotti, Carlos G; Martin, Mauricio G

    2011-03-01

    It is well established that memory formation and retention involve the coordinated flow of information from the post-synaptic site of particular neuronal populations to the nucleus, where short and long-lasting modifications of gene expression occur. With age, mnemonic, motor and sensorial alterations occur, and it is believed that extra failures in the mechanisms used for memory formation and storage are the cause of neurodegenerative pathologies like Alzheimer's disease. A prime candidate responsible for damage and loss of function during aging is the accumulation of reactive oxygen species, derived from normal oxidative metabolism. However, dysfunction in the aged brain is not paralleled by an increase in neuronal death, indicative that the brain is better suited to fight against the death signals generated from reactive oxygen species than against loss-of-function stimuli. A main aim of this laboratory is to understand how neurons perform and survive in the constitutive stress background represented by aging. In this report, we summarize our recent findings in relation to survival. © 2011 The Authors. Journal of Neurochemistry © 2011 International Society for Neurochemistry.

  11. Progressive seizure aggravation in the repeated 6-Hz corneal stimulation model is accompanied by marked increase in hippocampal p-ERK1/2 immunoreactivity in neurons

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    Carmela Giordano

    2016-12-01

    /2 levels in the third session. The vast majority of p-ERK1/2 immunopositive cells were co-labeled with FosB/ΔFosB antibodies, suggesting the existence of a relationship between the investigated markers in a subpopulation of neurons activated by seizures. These findings suggest that p-ERK1/2 are useful markers to define the aggravation of seizures and the response to anticonvulsant treatments. In particular, p-ERK1/2 expression clearly identified the involvement of hippocampal regions during seizure aggravation in the 6-Hz model.

  12. Increased number of orexin/hypocretin neurons with high and prolonged external stress-induced depression.

    Science.gov (United States)

    Jalewa, Jaishree; Wong-Lin, KongFatt; McGinnity, T Martin; Prasad, Girijesh; Hölscher, Christian

    2014-10-01

    It has been found that dysregulation in the orexin/hypocretin (Ox/HCRT) neuropeptide system in the lateral hypothalamus (LHA) is known to affect sleep disorder, depression and motor activities. However, to date there is no common agreement regarding the resulting specific changes induced in the Ox system. In this study, we inject corticosterone to produce stress-induced depressed mice and investigate the Ox neuronal and corresponding behavioural changes. Different doses (10, 20, 50mg/kgbw) of corticosterone were injected in adult mice, and then were tested in the open field test, forced swim test, tail suspension test, elevated plus maze test and motor activity measurements to validate the depressed animal model. Significant dose-dependent behavioural changes were observed in correlation with the doses of corticosterone. The effect is most significant and robust in the high 50mg/kgbw dose group five weeks after injection. Interestingly, we found on average a reduction in motor activity during the 12-hour dark phase (awake) of the depressed mice and no significant change during the light phase (asleep). Finally, using confocal microscopy, immunofluorescence (IF) analysis shows a significant increase (∼20%) in the number of Ox neurons in the LHA of the depressed mice as compared to the age-matched controls. This study suggests that an increase in Ox neuronal signaling may be functionally linked to high and prolonged external stress-induced depression. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Dogs Have the Most Neurons, Though Not the Largest Brain: Trade-Off between Body Mass and Number of Neurons in the Cerebral Cortex of Large Carnivoran Species.

    Science.gov (United States)

    Jardim-Messeder, Débora; Lambert, Kelly; Noctor, Stephen; Pestana, Fernanda M; de Castro Leal, Maria E; Bertelsen, Mads F; Alagaili, Abdulaziz N; Mohammad, Osama B; Manger, Paul R; Herculano-Houzel, Suzana

    2017-01-01

    Carnivorans are a diverse group of mammals that includes carnivorous, omnivorous and herbivorous, domesticated and wild species, with a large range of brain sizes. Carnivory is one of several factors expected to be cognitively demanding for carnivorans due to a requirement to outsmart larger prey. On the other hand, large carnivoran species have high hunting costs and unreliable feeding patterns, which, given the high metabolic cost of brain neurons, might put them at risk of metabolic constraints regarding how many brain neurons they can afford, especially in the cerebral cortex. For a given cortical size, do carnivoran species have more cortical neurons than the herbivorous species they prey upon? We find they do not; carnivorans (cat, mongoose, dog, hyena, lion) share with non-primates, including artiodactyls (the typical prey of large carnivorans), roughly the same relationship between cortical mass and number of neurons, which suggests that carnivorans are subject to the same evolutionary scaling rules as other non-primate clades. However, there are a few important exceptions. Carnivorans stand out in that the usual relationship between larger body, larger cortical mass and larger number of cortical neurons only applies to small and medium-sized species, and not beyond dogs: we find that the golden retriever dog has more cortical neurons than the striped hyena, African lion and even brown bear, even though the latter species have up to three times larger cortices than dogs. Remarkably, the brown bear cerebral cortex, the largest examined, only has as many neurons as the ten times smaller cat cerebral cortex, although it does have the expected ten times as many non-neuronal cells in the cerebral cortex compared to the cat. We also find that raccoons have dog-like numbers of neurons in their cat-sized brain, which makes them comparable to primates in neuronal density. Comparison of domestic and wild species suggests that the neuronal composition of carnivoran

  14. Dogs Have the Most Neurons, Though Not the Largest Brain: Trade-Off between Body Mass and Number of Neurons in the Cerebral Cortex of Large Carnivoran Species

    Science.gov (United States)

    Jardim-Messeder, Débora; Lambert, Kelly; Noctor, Stephen; Pestana, Fernanda M.; de Castro Leal, Maria E.; Bertelsen, Mads F.; Alagaili, Abdulaziz N.; Mohammad, Osama B.; Manger, Paul R.; Herculano-Houzel, Suzana

    2017-01-01

    Carnivorans are a diverse group of mammals that includes carnivorous, omnivorous and herbivorous, domesticated and wild species, with a large range of brain sizes. Carnivory is one of several factors expected to be cognitively demanding for carnivorans due to a requirement to outsmart larger prey. On the other hand, large carnivoran species have high hunting costs and unreliable feeding patterns, which, given the high metabolic cost of brain neurons, might put them at risk of metabolic constraints regarding how many brain neurons they can afford, especially in the cerebral cortex. For a given cortical size, do carnivoran species have more cortical neurons than the herbivorous species they prey upon? We find they do not; carnivorans (cat, mongoose, dog, hyena, lion) share with non-primates, including artiodactyls (the typical prey of large carnivorans), roughly the same relationship between cortical mass and number of neurons, which suggests that carnivorans are subject to the same evolutionary scaling rules as other non-primate clades. However, there are a few important exceptions. Carnivorans stand out in that the usual relationship between larger body, larger cortical mass and larger number of cortical neurons only applies to small and medium-sized species, and not beyond dogs: we find that the golden retriever dog has more cortical neurons than the striped hyena, African lion and even brown bear, even though the latter species have up to three times larger cortices than dogs. Remarkably, the brown bear cerebral cortex, the largest examined, only has as many neurons as the ten times smaller cat cerebral cortex, although it does have the expected ten times as many non-neuronal cells in the cerebral cortex compared to the cat. We also find that raccoons have dog-like numbers of neurons in their cat-sized brain, which makes them comparable to primates in neuronal density. Comparison of domestic and wild species suggests that the neuronal composition of carnivoran

  15. Dogs Have the Most Neurons, Though Not the Largest Brain: Trade-Off between Body Mass and Number of Neurons in the Cerebral Cortex of Large Carnivoran Species

    Directory of Open Access Journals (Sweden)

    Débora Jardim-Messeder

    2017-12-01

    Full Text Available Carnivorans are a diverse group of mammals that includes carnivorous, omnivorous and herbivorous, domesticated and wild species, with a large range of brain sizes. Carnivory is one of several factors expected to be cognitively demanding for carnivorans due to a requirement to outsmart larger prey. On the other hand, large carnivoran species have high hunting costs and unreliable feeding patterns, which, given the high metabolic cost of brain neurons, might put them at risk of metabolic constraints regarding how many brain neurons they can afford, especially in the cerebral cortex. For a given cortical size, do carnivoran species have more cortical neurons than the herbivorous species they prey upon? We find they do not; carnivorans (cat, mongoose, dog, hyena, lion share with non-primates, including artiodactyls (the typical prey of large carnivorans, roughly the same relationship between cortical mass and number of neurons, which suggests that carnivorans are subject to the same evolutionary scaling rules as other non-primate clades. However, there are a few important exceptions. Carnivorans stand out in that the usual relationship between larger body, larger cortical mass and larger number of cortical neurons only applies to small and medium-sized species, and not beyond dogs: we find that the golden retriever dog has more cortical neurons than the striped hyena, African lion and even brown bear, even though the latter species have up to three times larger cortices than dogs. Remarkably, the brown bear cerebral cortex, the largest examined, only has as many neurons as the ten times smaller cat cerebral cortex, although it does have the expected ten times as many non-neuronal cells in the cerebral cortex compared to the cat. We also find that raccoons have dog-like numbers of neurons in their cat-sized brain, which makes them comparable to primates in neuronal density. Comparison of domestic and wild species suggests that the neuronal

  16. Cannabinoid receptor CB1 mediates baseline and activity-induced survival of new neurons in adult hippocampal neurogenesis

    Directory of Open Access Journals (Sweden)

    Müller Anke

    2010-06-01

    Full Text Available Abstract Background Adult neurogenesis is a particular example of brain plasticity that is partially modulated by the endocannabinoid system. Whereas the impact of synthetic cannabinoids on the neuronal progenitor cells has been described, there has been lack of information about the action of plant-derived extracts on neurogenesis. Therefore we here focused on the effects of Δ9-tetrahydrocannabinol (THC and Cannabidiol (CBD fed to female C57Bl/6 and Nestin-GFP-reporter mice on proliferation and maturation of neuronal progenitor cells and spatial learning performance. In addition we used cannabinoid receptor 1 (CB1 deficient mice and treatment with CB1 antagonist AM251 in Nestin-GFP-reporter mice to investigate the role of the CB1 receptor in adult neurogenesis in detail. Results THC and CBD differed in their effects on spatial learning and adult neurogenesis. CBD did not impair learning but increased adult neurogenesis, whereas THC reduced learning without affecting adult neurogenesis. We found the neurogenic effect of CBD to be dependent on the CB1 receptor, which is expressed over the whole dentate gyrus. Similarly, the neurogenic effect of environmental enrichment and voluntary wheel running depends on the presence of the CB1 receptor. We found that in the absence of CB1 receptors, cell proliferation was increased and neuronal differentiation reduced, which could be related to CB1 receptor mediated signaling in Doublecortin (DCX-expressing intermediate progenitor cells. Conclusion CB1 affected the stages of adult neurogenesis that involve intermediate highly proliferative progenitor cells and the survival and maturation of new neurons. The pro-neurogenic effects of CBD might explain some of the positive therapeutic features of CBD-based compounds.

  17. Spiking neurons in a hierarchical self-organizing map model can learn to develop spatial and temporal properties of entorhinal grid cells and hippocampal place cells.

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    Praveen K Pilly

    Full Text Available Medial entorhinal grid cells and hippocampal place cells provide neural correlates of spatial representation in the brain. A place cell typically fires whenever an animal is present in one or more spatial regions, or places, of an environment. A grid cell typically fires in multiple spatial regions that form a regular hexagonal grid structure extending throughout the environment. Different grid and place cells prefer spatially offset regions, with their firing fields increasing in size along the dorsoventral axes of the medial entorhinal cortex and hippocampus. The spacing between neighboring fields for a grid cell also increases along the dorsoventral axis. This article presents a neural model whose spiking neurons operate in a hierarchy of self-organizing maps, each obeying the same laws. This spiking GridPlaceMap model simulates how grid cells and place cells may develop. It responds to realistic rat navigational trajectories by learning grid cells with hexagonal grid firing fields of multiple spatial scales and place cells with one or more firing fields that match neurophysiological data about these cells and their development in juvenile rats. The place cells represent much larger spaces than the grid cells, which enable them to support navigational behaviors. Both self-organizing maps amplify and learn to categorize the most frequent and energetic co-occurrences of their inputs. The current results build upon a previous rate-based model of grid and place cell learning, and thus illustrate a general method for converting rate-based adaptive neural models, without the loss of any of their analog properties, into models whose cells obey spiking dynamics. New properties of the spiking GridPlaceMap model include the appearance of theta band modulation. The spiking model also opens a path for implementation in brain-emulating nanochips comprised of networks of noisy spiking neurons with multiple-level adaptive weights for controlling autonomous

  18. Enantioselectivity of 2,2',3,5',6-Pentachlorobiphenyl (PCB 95) Atropisomers toward Ryanodine Receptors (RyRs) and Their Influences on Hippocampal Neuronal Networks.

    Science.gov (United States)

    Feng, Wei; Zheng, Jing; Robin, Gaëlle; Dong, Yao; Ichikawa, Makoto; Inoue, Yoshihisa; Mori, Tadashi; Nakano, Takeshi; Pessah, Isaac N

    2017-12-19

    Nineteen ortho-substituted PCBs are chiral and found enantioselectively enriched in ecosystems. Their differential actions on biological targets are not understood. PCB 95 (2,2',3,5',6-pentachlorobiphenyl), a chiral PCB of current environmental relevance, is among the most potent toward modifying ryanodine receptors (RyR) function and Ca2+ signaling. PCB 95 enantiomers are separated and assigned aR- and aS-PCB 95 using three chiral-column HPLC and circular dichroism spectroscopy. Studies of RyR1-enriched microsomes show aR-PCB 95 with >4× greater potency (EC50 = 0.20 ± 0.05 μM), ∼ 1.3× higher efficacy (Bmax = 3.74 ± 0.07 μM) in [3H]Ryanodine-binding and >3× greater rates (R = 7.72 ± 0.31 nmol/sec/mg) of Ca2+ efflux compared with aS-PCB 95, whereas racemate has intermediate activity. aR-PCB 95 has modest selectivity for RyR2, and lower potency than racemate toward the RyR isoform mixture in brain membranes. Chronic exposure of hippocampal neuronal networks to nanomolar PCB 95 during a critical developmental period shows divergent influences on synchronous Ca2+ oscillation (SCO): rac-PCB 95 increasing and aR-PCB 95 decreasing SCO frequency at 50 nM, although the latter's effects are nonmonotonic at higher concentration. aS-PCB95 shows the greatest influence on inhibiting responses to 20 Hz electrical pulse trains. Considering persistence of PCB 95 in the environment, stereoselectivity toward RyRs and developing neuronal networks may clarify health risks associated with enantioisomeric enrichment of PCBs.

  19. Presynaptic LRP4 promotes synapse number and function of excitatory CNS neurons.

    Science.gov (United States)

    Mosca, Timothy J; Luginbuhl, David J; Wang, Irving E; Luo, Liqun

    2017-06-13

    Precise coordination of synaptic connections ensures proper information flow within circuits. The activity of presynaptic organizing molecules signaling to downstream pathways is essential for such coordination, though such entities remain incompletely known. We show that LRP4, a conserved transmembrane protein known for its postsynaptic roles, functions presynaptically as an organizing molecule. In the Drosophila brain, LRP4 localizes to the nerve terminals at or near active zones. Loss of presynaptic LRP4 reduces excitatory (not inhibitory) synapse number, impairs active zone architecture, and abolishes olfactory attraction - the latter of which can be suppressed by reducing presynaptic GABA B receptors. LRP4 overexpression increases synapse number in excitatory and inhibitory neurons, suggesting an instructive role and a common downstream synapse addition pathway. Mechanistically, LRP4 functions via the conserved kinase SRPK79D to ensure normal synapse number and behavior. This highlights a presynaptic function for LRP4, enabling deeper understanding of how synapse organization is coordinated.

  20. Prenatal exposure to carbamazepine reduces hippocampal and cortical neuronal cell population in new-born and young mice without detectable effects on learning and memory.

    Directory of Open Access Journals (Sweden)

    Elin Åberg

    Full Text Available Pregnant women with epilepsy have to balance maternal and fetal risks associated with uncontrolled seizures against the potential teratogenic effects from antiepileptic drugs (AEDs. Carbamazepine (CBZ is among the four most commonly used AEDs for treatment of pregnant epileptic women. We previously reported that new-born children had a decreased head circumference after in utero CBZ exposure. This study investigates how prenatal exposure of CBZ influences the number of neurons in new-born and young mouse hippocampus, amygdala and cortex cerebri. Clinical studies describe inconclusive results on if prenatal CBZ treatment influences cognition. Here we investigate this issue in mice using two well characterized cognitive tasks, the passive avoidance test and the Morris water maze test. Prenatal exposure of CBZ reduced the number of neurons (NeuN-immunoreactive cells in the new-born mouse hippocampus with 50% compared to non-exposed mice. A reduction of neurons (20% in hippocampus was still observed when the animals were 5 weeks old. These mice also displayed a 25% reduction of neurons in cortex cerebri. Prenatal CBZ treatment did not significantly impair learning and memory measured in the passive avoidance test and in the Morris water maze. However, these mice displayed a higher degree of thigmotaxic behaviour than the control mice. The body weight of prenatally CBZ exposed five-week old mice were lower compared to control mice not exposed to CBZ (p = 0.001. In conclusion, prenatal exposure to CBZ reduces the number of neurons dramatically in areas important for cognition such as hippocampus and cortex, without severe impairments on learning and memory. These results are in line with some clinical studies, reporting that CBZ has minor negative effects on cognition. The challenge for future studies are to segment out what possible effects a reduction of neurons could have on different types of cognition, like intellectual ability and social

  1. Quercetin Protects against Okadaic Acid-Induced Injury via MAPK and PI3K/Akt/GSK3β Signaling Pathways in HT22 Hippocampal Neurons.

    Directory of Open Access Journals (Sweden)

    Wei Jiang

    Full Text Available Increasing evidence shows that oxidative stress and the hyperphosphorylation of tau protein play essential roles in the progression of Alzheimer's disease (AD. Quercetin is a major flavonoid that has anti-oxidant, anti-cancer and anti-inflammatory properties. We investigated the neuroprotective effects of quercetin to HT22 cells (a cell line from mouse hippocampal neurons. We found that Okadaic acid (OA induced the hyperphosphorylation of tau protein at Ser199, Ser396, Thr205, and Thr231 and produced oxidative stress to the HT22 cells. The oxidative stress suppressed the cell viability and decreased the levels of lactate dehydrogenase (LDH, superoxide dismutase (SOD, mitochondria membrane potential (MMP and Glutathione peroxidase (GSH-Px. It up-regulated malondialdehyde (MDA production and intracellular reactive oxygen species (ROS. In addition, phosphoinositide 3 kinase/protein kinase B/Glycogen synthase kinase3β (PI3K/Akt/GSK3β and mitogen activated protein kinase (MAPK were also involved in this process. We found that pre-treatment with quercetin can inhibited OA-induced the hyperphosphorylation of tau protein and oxidative stress. Moreover, pre-treatment with quercetin not only inhibited OA-induced apoptosis via the reduction of Bax, and up-regulation of cleaved caspase 3, but also via the inhibition of PI3K/Akt/GSK3β, MAPKs and activation of NF-κB p65. Our findings suggest the therapeutic potential of quercetin to treat AD.

  2. Transcription factor NF-kappaB is transported to the nucleus via cytoplasmic dynein/dynactin motor complex in hippocampal neurons.

    Directory of Open Access Journals (Sweden)

    Ilja Mikenberg

    2007-07-01

    Full Text Available Long-term changes in synaptic plasticity require gene transcription, indicating that signals generated at the synapse must be transported to the nucleus. Synaptic activation of hippocampal neurons is known to trigger retrograde transport of transcription factor NF-kappaB. Transcription factors of the NF-kappaB family are widely expressed in the nervous system and regulate expression of several genes involved in neuroplasticity, cell survival, learning and memory.In this study, we examine the role of the dynein/dynactin motor complex in the cellular mechanism targeting and transporting activated NF-kappaB to the nucleus in response to synaptic stimulation. We demonstrate that overexpression of dynamitin, which is known to dissociate dynein from microtubules, and treatment with microtubule-disrupting drugs inhibits nuclear accumulation of NF-kappaB p65 and reduces NF-kappaB-dependent transcription activity. In this line, we show that p65 is associated with components of the dynein/dynactin complex in vivo and in vitro and that the nuclear localization sequence (NLS within NF-kappaB p65 is essential for this binding.This study shows the molecular mechanism for the retrograde transport of activated NF-kappaB from distant synaptic sites towards the nucleus.

  3. Polyozellin, a key constituent of the edible mushroom Polyozellus multiplex, attenuates glutamate-induced mouse hippocampal neuronal HT22 cell death.

    Science.gov (United States)

    Yang, Eun-Ju; Song, Kyung-Sik

    2015-12-01

    Polyozellus multiplex (PM), a Korean edible mushroom, has biological activities such as chemoprevention of stomach cancer, inhibition of lipid peroxidation, and reduction of prolyl endopeptidase activity. However, there are little reports on the protective effects of PM or its constituents against glutamate-induced mouse hippocampal neuronal cell (HT22) death. In this study, polyozellin (PZ), a key constituent of PM, was applied to glutamate-treated HT22 cells to evaluate its neuroprotective mechanisms. PZ (25 μM) dramatically increased the HT22 cell viability when the cell death was induced by 5 mM glutamate for 12 h, which was mediated by inhibition of Ca(2+) influx, intracellular reactive oxygen species (ROS) production, and lipid peroxidation. PZ also regulated expression of Bid, Bcl-2, and apoptosis-inducing factor (AIF), as well as phosphorylation of mitogen-activated protein kinases (MAPKs). These data suggest that PM and its constituent PZ might be useful for prevention and treatment of neurodegenerative disorders.

  4. Inhibitory effects of levetiracetam on the high-voltage-activated L-type Ca²⁺ channels in hippocampal CA3 neurons of spontaneously epileptic rat (SER).

    Science.gov (United States)

    Yan, Hai-Dun; Ishihara, Kumatoshi; Seki, Takahiro; Hanaya, Ryosuke; Kurisu, Kaoru; Arita, Kazunori; Serikawa, Tadao; Sasa, Masashi

    2013-01-01

    Levetiracetam (LEV) is a widely used antiepileptic agent for partial refractory epilepsy in humans. LEV has unique antiepileptic effects in that it does not inhibit electroshock- or pentylenetetrazol-induced convulsion, but does inhibit seizures in kindling animal and spontaneously epileptic rat (SER: zi/zi, tm/tm) that shows both tonic convulsion and absence-like seizures. LEV also has unique characteristics in terms of its antiepileptic mechanism; it has no activity on Na⁺ and K⁺ channels or on glutamate and GABA(A) receptors. Recently, we found that LEV inhibits the depolarization shift and accompanying repetitive firing induced by mossy fiber stimulation in CA3 neurons of SER hippocampal slices. Therefore, this study was performed to determine whether LEV could inhibit the voltage-activated L-type Ca²⁺ current of hippocampal CA3 neurons obtained from SER and the non-epileptic Wistar rat. As previously reported, SER CA3 neurons were classified into type 1 and type 2 neurons. The application of LEV (100 μM) elevated the threshold for activation of the Ca²⁺ current, which was lowered in SER type 1 neurons and reduced the current size. Type 2 neurons of SER have a similar current-voltage relationship to Wistar rat neurons and the decay component of Ca²⁺ current during depolarization pulse in type 2 neurons was found to be smaller than that in Wistar rat neurons. LEV (100 μM) also reduced Ca²⁺ current in SER type 2 neurons. The effects of LEV were examined on such type 2 SER hippocampal CA3 neurons, compared with those on Wistar rat CA3 neurons. Application of LEV (10 μM) produced a significant decrease of amplitude of the Ca²⁺ current in SER neurons, although at this concentration of LEV there was no statistically significant decrease in the amplitude of Ca²⁺ current in Wistar rat neurons. Furthermore, LEV (100 nM-1 mM) reduced the Ca²⁺ current in a concentration-dependent manner in both SER and Wistar rat neurons, but the inhibition was

  5. Aging and Exercise Affect Hippocampal Neurogenesis via Different Mechanisms.

    Science.gov (United States)

    Yang, Ting-Ting; Lo, Chen-Peng; Tsai, Pei-Shan; Wu, Shih-Ying; Wang, Tzu-Feng; Chen, Yun-Wen; Jiang-Shieh, Ya-Fen; Kuo, Yu-Min

    2015-01-01

    The rate of neurogenesis is determined by 1) the number of neural stem/progenitor cells (NSCs), 2) proliferation of NSCs, 3) neuron lineage specification, and 4) survival rate of the newborn neurons. Aging lowers the rate of hippocampal neurogenesis, while exercise (Ex) increases this rate. However, it remains unclear which of the determinants are affected by aging and Ex. We characterized the four determinants in different age groups (3, 6, 9, 12, 21 months) of mice that either received one month of Ex training or remained sedentary. Bromodeoxyuridine (BrdU) was injected two hours before sacrificing the mice to label the proliferating cells. The results showed that the number of newborn neurons massively decreased (>95%) by the time the mice reached nine months of age. The number of NSC was mildly reduced during aging, while Ex delayed such decline. The proliferation rates were greatly decreased by the time the mice were 9-month-old and Ex could not improve the rates. The rates of neuron specification were decreased during aging, while Ex increased the rates. The survival rate was not affected by age or Ex. Aging greatly reduced newborn neuron maturation, while Ex potently enhanced it. In conclusion, age-associated decline of hippocampal neurogenesis is mainly caused by reduction of NSC proliferation. Although Ex increases the NSC number and neuron specification rates, it doesn't restore the massive decline of NSC proliferation rate. Hence, the effect of Ex on the rate of hippocampal neurogenesis during aging is limited, but Ex does enhance the maturation of newborn neurons.

  6. Cajal body number and nucleolar size correlate with the cell body mass in human sensory ganglia neurons.

    Science.gov (United States)

    Berciano, Maria T; Novell, Mariona; Villagra, Nuria T; Casafont, Iñigo; Bengoechea, Rocio; Val-Bernal, J Fernado; Lafarga, Miguel

    2007-06-01

    This paper studies the cell size-dependent organization of the nucleolus and Cajal bodies (CBs) in dissociated human dorsal root ganglia (DRG) neurons from autopsy tissue samples of patients without neurological disease. The quantitative analysis of nucleoli with an anti-fibrillarin antibody showed that all neurons have only one nucleolus. However, the nucleolar volume and the number of fibrillar centers per nucleolus significantly increase as a function of cell body size. Immunostaining for coilin demonstrated the presence of numerous CBs in DRG neurons (up to 20 in large size neurons). The number of CBs per neuron correlated positively with the cell body volume. Light and electron microscopy immunocytochemical analysis revealed the concentration of coilin, snRNPs, SMN and fibrillarin in CBs of DRG neurons. CBs were frequently associated with the nucleolus, active chromatin domains and PML bodies, but not with telomeres. Our results support the view that the nucleolar volume and number of both fibrillar centers and CBs depend on the cell body mass, a parameter closely related to transcriptional and synaptic activity in mammalian neurons. Moreover, the unusual large number of CBs could facilitate the transfer of RNA processing components from CBs to nucleolar and nucleoplasmic sites of RNA processing.

  7. The impact of cocaine on adult hippocampal neurogenesis: Potential neurobiological mechanisms and contributions to maladaptive cognition in cocaine addiction disorder.

    Science.gov (United States)

    Castilla-Ortega, Estela; Ladrón de Guevara-Miranda, David; Serrano, Antonia; Pavón, Francisco J; Suárez, Juan; Rodríguez de Fonseca, Fernando; Santín, Luis J

    2017-10-01

    After discovering that addictive drugs alter adult neurogenesis, the potential role of adult-born hippocampal neurons in drug addiction has become a promising research field, in which cocaine is the most frequently investigated drug. Although a substantial amount of pre-clinical evidence has accumulated, additional studies are required to reveal the mechanisms by which cocaine modulates adult hippocampal neurogenesis (AHN) and determine whether these adult-born neurons have a role in cocaine-related behaviors, such as cocaine-mediated cognitive symptoms. First, this review will summarize the cocaine-induced alterations in a number of neurobiological factors (neurotransmitters, neurotrophins, glucocorticoids, inflammatory mediators) that likely regulate both hippocampal-dependent learning and adult hippocampal neurogenesis after cocaine exposure. A separate section will provide a detailed review of the available literature that challenges the common view that cocaine reduces adult hippocampal neurogenesis. In fact, cocaine has a short-term anti-proliferative role, but the young adult-born neurons are apparently spared, or even enhanced, following certain cocaine protocols. Thus, we will try to reconcile this evidence with the hippocampal-dependent cognitive symptoms that are typically observed in cocaine addicts, and we will propose new directions for future studies to test the relevant hypothesis. Based on the evidence presented here, the regulation of adult hippocampal neurogenesis might be one of the many mechanisms by which cocaine sculpts hippocampus-dependent learning. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. Stereological estimate of the total number of neurons in spinal segment D9 of the red-eared turtle

    DEFF Research Database (Denmark)

    Walløe, Solveig; Nissen, Ulla Vig; Berg, Rune W

    2011-01-01

    The red-eared turtle is an important animal model for investigating the neural activity in the spinal circuit that generates motor behavior. However, basic anatomical features, including the number of neurons in the spinal segments involved, are unknown. In the present study, we estimate the total...... number of neurons in segment D9 of the spinal cord in the red-eared turtle (Trachemys scripta elegans) using stereological cell counting methods. In transverse spinal cord sections stained with modified Giemsa, motoneurons (MNs), interneurons (INs), and non-neuronal cells were distinguished according...

  9. Food restriction reduces neurogenesis in the avian hippocampal formation.

    Directory of Open Access Journals (Sweden)

    Barbara-Anne Robertson

    Full Text Available The mammalian hippocampus is particularly vulnerable to chronic stress. Adult neurogenesis in the dentate gyrus is suppressed by chronic stress and by administration of glucocorticoid hormones. Post-natal and adult neurogenesis are present in the avian hippocampal formation as well, but much less is known about its sensitivity to chronic stressors. In this study, we investigate this question in a commercial bird model: the broiler breeder chicken. Commercial broiler breeders are food restricted during development to manipulate their growth curve and to avoid negative health outcomes, including obesity and poor reproductive performance. Beyond knowing that these chickens are healthier than fully-fed birds and that they have a high motivation to eat, little is known about how food restriction impacts the animals' physiology. Chickens were kept on a commercial food-restricted diet during the first 12 weeks of life, or released from this restriction by feeding them ad libitum from weeks 7-12 of life. To test the hypothesis that chronic food restriction decreases the production of new neurons (neurogenesis in the hippocampal formation, the cell proliferation marker bromodeoxyuridine was injected one week prior to tissue collection. Corticosterone levels in blood plasma were elevated during food restriction, even though molecular markers of hypothalamic-pituitary-adrenal axis activation did not differ between the treatments. The density of new hippocampal neurons was significantly reduced in the food-restricted condition, as compared to chickens fed ad libitum, similar to findings in rats at a similar developmental stage. Food restriction did not affect hippocampal volume or the total number of neurons. These findings indicate that in birds, like in mammals, reduction in hippocampal neurogenesis is associated with chronically elevated corticosterone levels, and therefore potentially with chronic stress in general. This finding is consistent with the

  10. Interleukin-17 inhibits Adult Hippocampal Neurogenesis

    Science.gov (United States)

    Liu, Qiang; Xin, Wei; He, Ping; Turner, Dharshaun; Yin, Junxiang; Gan, Yan; Shi, Fu-Dong; Wu, Jie

    2014-01-01

    Interleukin 17(A) (IL-17) is a potent pro-inflammatory cytokine that acts as a central regulator of inflammatory response within the brain, but its physiological roles under non-inflammatory conditions remain elusive. Here we report that endogenous IL-17 ablates neurogenesis in the adult dentate gyrus (DG) of hippocampus. Genetic deletion of IL-17 increased the number of adult-born neurons in the DG. Further, we found that IL-17 deletion altered cytokine network, facilitated basal excitatory synaptic transmission, enhanced intrinsic neuronal excitability, and increased expression of proneuronal genes in neuronal progenitor cells (NPCs). Our findings suggest a profound role of IL-17 in the negative regulation of adult hippocampal neurogenesis under physiology conditions. PMID:25523081

  11. Regulation of differentiation flux by Notch signalling influences the number of dopaminergic neurons in the adult brain

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    Niurka Trujillo-Paredes

    2016-03-01

    Full Text Available Notch signalling is a well-established pathway that regulates neurogenesis. However, little is known about the role of Notch signalling in specific neuronal differentiation. Using Dll1 null mice, we found that Notch signalling has no function in the specification of mesencephalic dopaminergic neural precursor cells (NPCs, but plays an important role in regulating their expansion and differentiation into neurons. Premature neuronal differentiation was observed in mesencephalons of Dll1-deficient mice or after treatment with a Notch signalling inhibitor. Coupling between neurogenesis and dopaminergic differentiation was indicated from the coincident emergence of neuronal and dopaminergic markers. Early in differentiation, decreasing Notch signalling caused a reduction in NPCs and an increase in dopaminergic neurons in association with dynamic changes in the proportion of sequentially-linked dopaminergic NPCs (Msx1/2+, Ngn2+, Nurr1+. These effects in differentiation caused a significant reduction in the number of dopaminergic neurons produced. Accordingly, Dll1 haploinsufficient adult mice, in comparison with their wild-type littermates, have a consistent reduction in neuronal density that was particularly evident in the substantia nigra pars compacta. Our results are in agreement with a mathematical model based on a Dll1-mediated regulatory feedback loop between early progenitors and their dividing precursors that controls the emergence and number of dopaminergic neurons.

  12. Neuroprotective effects of α-iso-cubebene against glutamate-induced damage in the HT22 hippocampal neuronal cell line.

    Science.gov (United States)

    Park, Sun Young; Jung, Won Jung; Kang, Jum Soon; Kim, Cheol-Min; Park, Geuntae; Choi, Young-Whan

    2015-02-01

    Since oxidative stress is critically involved in excitotoxic damage, we sought to determine whether the activation of the transcription factors, cAMP-responsive element binding protein (CREB) and nuclear factor (erythroid-derived 2)-like 2 (Nrf2, also known as NFE2L2), by α-iso-cubebene is involved in its protective effects against glutamate-induced neuronal cell death. Pre-treatment with α-iso-cubebene significantly attenuated glutamate-induced cytotoxicity in mouse hippocampus-derived neuronal cells. α-iso-cubebene also reduced the glutamate-induced generation of reactive oxygen species and calcium influx, thus preventing apoptotic cell death. α-iso-cubebene inhibited glutamate-induced mitochondrial membrane depolarization and, consequently, inhibited the release of the apoptosis-inducing factor from the mitochondria. Immunoblot anlaysis revealed that the phosphorylation of extracellular signal-regulated kinase (ERK) by glutamate was reduced in the presence of α-iso-cubebene. α-iso-cubebene activated protein kinase A (PKA), CREB and Nrf2, which mediate the expression of the antioxidant enzymes, heme oxygenase-1 (HO-1) and NAD(P)H dehydrogenase [quinone] 1 (NQO1), involved in neuroprotection. In addition, α-iso-cubebene induced the expression of antioxidant responsive element and CRE transcriptional activity, thus conferring neuroprotection against glutamate-induced oxidative injury. α-iso-cubebene also induced the expression of Nrf2-dependent genes encoding HO-1 and NQO1. Furthermore, the knockdown of CREB and Nrf2 by small interfering RNA attenuated the neuroprotective effects of α-iso-cubebene. Taken together, our results indicate that α-iso-cubebene protects HT22 cells from glutamate-induced oxidative damage through the activation of Nrf2/HO-1/NQO-1, as well as through the PKA and CREB signaling pathways.

  13. The effect of intrathecal delivery of bone marrow stromal cells on hippocampal neurons in rat model of Alzheimer’s disease

    Directory of Open Access Journals (Sweden)

    Mina Eftekharzadeh

    2015-05-01

    Full Text Available Objective(s: Intracerebral injection of bone marrow stromal cells (BMSCs is being investigated as a therapeutic tool to prevent Alzheimer's disease (AD. Our aim was to investigate the effects of BMSCs by intrathecal injection in AD rat model. Materials and Methods: BMSCs were obtained from the bone marrow of Wistar rat and transplanted into AD rat model via intrathecal injection. The rat model had received an injection of β amyloid into the hippocampus for histological and immunohistochemical studies. Results: Histological examination of the brains in transplanted rats compared to controls demonstrated the migration of BrdU-labeled BMSCs from the site of delivery, confirmed the differentiation of BMSCs transplanted cells into the cholinergic neurons, and increased number of healthy and decreased number of dark neurons. Conclusion: Our results showed that BMSCs intratechal administration could be a promising method for treatment ofAlzheimer’s disease in rat model.

  14. Quantifying the Behavioural Relevance of Hippocampal Neurogenesis: e113855

    National Research Council Canada - National Science Library

    Stanley E Lazic; Johannes Fuss; Peter Gass

    2014-01-01

    .... A systematic review of the literature was conducted and the data reanalysed using causal mediation analysis, which can estimate the behavioural contribution of new hippocampal neurons separately...

  15. No Reduction of Spindle Neuron Number in Frontoinsular Cortex in Autism

    Science.gov (United States)

    Kennedy, Daniel P.; Semendeferi, Katerina; Courchesne, Eric

    2007-01-01

    It has been suggested that spindle neurons, an evolutionarily unique type of neuron, might be involved in higher-order social, emotional, and cognitive functions. As such, it was hypothesized that these neurons may be particularly important to the pathophysiology of autism, a disease characterized in part by disruption of higher-order social and…

  16. Decreased Neuron Number and Synaptic Plasticity in SIRT3-Knockout Mice with Poor Remote Memory.

    Science.gov (United States)

    Kim, Hyopil; Kim, Somi; Choi, Ja Eun; Han, DaeHee; Koh, Soo Min; Kim, Hyun-Seok; Kaang, Bong-Kiun

    2017-10-26

    The sirtuin family of proteins consists of nicotinamide adenine dinucleotide-dependent deacetylases that are involved in the response to calorie restriction and various physiological phenomena, such as aging and cognition. One of these proteins, sirtuin 3 (SIRT3), is localized in the mitochondria and protects the cell against oxidative or metabolic stress. Sirtuin protein deficiencies have been shown to accelerate neurodegeneration in neurotoxic conditions. The mechanisms underlying the involvement of SIRT3 in cognition remain unclear. Interestingly, SIRT1, another member of the sirtuin family, has been reported to modulate synaptic plasticity and memory formation. To learn more about these proteins, we examined the behavior and cognitive functions of Sirt3-knockout mice. The mice exhibited poor remote memory. Consistent with this, long-term potentiation was impaired in the Sirt3-knockout mice, and they exhibited decreased neuronal number in the anterior cingulate cortex, which seemed to contribute to their memory deficiencies.

  17. SUMOylation is required for glycine-induced increases in AMPA receptor surface expression (ChemLTP in hippocampal neurons.

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    Nadia Jaafari

    Full Text Available Multiple pathways participate in the AMPA receptor trafficking that underlies long-term potentiation (LTP of synaptic transmission. Here we demonstrate that protein SUMOylation is required for insertion of the GluA1 AMPAR subunit following transient glycine-evoked increase in AMPA receptor surface expression (ChemLTP in dispersed neuronal cultures. ChemLTP increases co-localisation of SUMO-1 and the SUMO conjugating enzyme Ubc9 and with PSD95 consistent with the recruitment of SUMOylated proteins to dendritic spines. In addition, we show that ChemLTP increases dendritic levels of SUMO-1 and Ubc9 mRNA. Consistent with activity dependent translocation of these mRNAs to sites near synapses, levels of the mRNA binding and dendritic transport protein CPEB are also increased by ChemLTP. Importantly, reducing the extent of substrate protein SUMOylation by overexpressing the deSUMOylating enzyme SENP-1 or inhibiting SUMOylation by expressing dominant negative Ubc9 prevent the ChemLTP-induced increase in both AMPAR surface expression and dendritic SUMO-1 mRNA. Taken together these data demonstrate that SUMOylation of synaptic protein(s involved in AMPA receptor trafficking is necessary for activity-dependent increases in AMPAR surface expression.

  18. Qualitative and quantitative estimation of comprehensive synaptic connectivity in short- and long-term cultured rat hippocampal neurons with new analytical methods inspired by Scatchard and Hill plots

    Energy Technology Data Exchange (ETDEWEB)

    Tanamoto, Ryo; Shindo, Yutaka; Niwano, Mariko [Department of Biosciences and Informatics, Faculty of Science and Technology, Keio University (Japan); Matsumoto, Yoshinori [Department of Applied Physics and Physico-Informatics, Faculty of Science and Technology, Keio University (Japan); Miki, Norihisa [Department of Mechanical Engineering, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa, 223-8522 (Japan); Hotta, Kohji [Department of Biosciences and Informatics, Faculty of Science and Technology, Keio University (Japan); Oka, Kotaro, E-mail: oka@bio.keio.ac.jp [Department of Biosciences and Informatics, Faculty of Science and Technology, Keio University (Japan)

    2016-03-18

    To investigate comprehensive synaptic connectivity, we examined Ca{sup 2+} responses with quantitative electric current stimulation by indium-tin-oxide (ITO) glass electrode with transparent and high electro-conductivity. The number of neurons with Ca{sup 2+} responses was low during the application of stepwise increase of electric current in short-term cultured neurons (less than 17 days in-vitro (DIV)). The neurons cultured over 17 DIV showed two-type responses: S-shaped (sigmoid) and monotonous saturated responses, and Scatchard plots well illustrated the difference of these two responses. Furthermore, sigmoid like neural network responses over 17 DIV were altered to the monotonous saturated ones by the application of the mixture of AP5 and CNQX, specific blockers of NMDA and AMPA receptors, respectively. This alternation was also characterized by the change of Hill coefficients. These findings indicate that the neural network with sigmoid-like responses has strong synergetic or cooperative synaptic connectivity via excitatory glutamate synapses. - Highlights: • We succeed to evaluate the maturation of neural network by Scathard and Hill Plots. • Long-term cultured neurons showed two-type responses: sigmoid and monotonous. • The sigmoid-like increase indicates the cooperatevity of neural networks. • Excitatory glutamate synapses cause the cooperatevity of neural networks.

  19. Hippocampal “Time Cells”: Time versus Path Integration

    Science.gov (United States)

    Kraus, Benjamin J.; Robinson, Robert J.; White, John A.; Eichenbaum, Howard; Hasselmo, Michael E.

    2014-01-01

    SUMMARY Recent studies have reported the existence of hippocampal “time cells,” neurons that fire at particular moments during periods when behavior and location are relatively constant. However, an alternative explanation of apparent time coding is that hippocampal neurons “path integrate” to encode the distance an animal has traveled. Here, we examined hippocampal neuronal firing patterns as rats ran in place on a treadmill, thus “clamping” behavior and location, while we varied the treadmill speed to distinguish time elapsed from distance traveled. Hippocampal neurons were strongly influenced by time and distance, and less so by minor variations in location. Furthermore, the activity of different neurons reflected integration over time and distance to varying extents, with most neurons strongly influenced by both factors and some significantly influenced by only time or distance. Thus, hippocampal neuronal networks captured both the organization of time and distance in a situation where these dimensions dominated an ongoing experience. PMID:23707613

  20. Deleterious impacts of a 900-MHz electromagnetic field on hippocampal pyramidal neurons of 8-week-old Sprague Dawley male rats.

    Science.gov (United States)

    Şahin, Arzu; Aslan, Ali; Baş, Orhan; İkinci, Ayşe; Özyılmaz, Cansu; Sönmez, Osman Fikret; Çolakoğlu, Serdar; Odacı, Ersan

    2015-10-22

    Children are at potential risk due to their intense use of mobile phones. We examined 8-week-old rats because this age of the rats is comparable with the preadolescent period in humans. The number of pyramidal neurons in the cornu ammonis of the Sprague Dawley male rat (8-weeks old, weighing 180-250 g) hippocampus following exposure to a 900 MHz (MHz) electromagnetic field (EMF) were examined. The study consisted of control (CN-G), sham exposed (SHM-EG) and EMF exposed (EMF-EG) groups with 6 rats in each. The EMF-EG rats were exposed to 900 MHz EMF (1h/day for 30 days) in an EMF jar. The SHM-EG rats were placed in the EMF jar but not exposed to the EMF (1h/day for 30 days). The CN-G rats were not placed into the exposure jar and were not exposed to the EMF during the study period. All animals were sacrificed at the end of the experiment, and their brains were removed for histopathological and stereological analysis. The number of pyramidal neurons in the cornu ammonis of the hippocampus was estimated on Cresyl violet stained sections of the brain using the optical dissector counting technique. Histopathological evaluations were also performed on these sections. Histopathological observation showed abundant cells with abnormal, black or dark blue cytoplasm and shrunken morphology among the normal pyramidal neurons. The largest lateral ventricles were observed in the EMF-EG sections compared to those from the other groups. Stereological analyses showed that the total number of pyramidal neurons in the cornu ammonis of the EMF-EG rats was significantly lower than those in the CN-G (pEMF exposure. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Ketamine Affects the Neurogenesis of the Hippocampal Dentate Gyrus in 7-Day-Old Rats.

    Science.gov (United States)

    Huang, He; Liu, Cun-Ming; Sun, Jie; Hao, Ting; Xu, Chun-Mei; Wang, Dan; Wu, Yu-Qing

    2016-08-01

    Ketamine has been reported to cause neonatal neurotoxicity via a neuronal apoptosis mechanism; however, no in vivo research has reported whether ketamine could affect postnatal neurogenesis in the hippocampal dentate gyrus (DG). A growing number of experiments suggest that postnatal hippocampal neurogenesis is the foundation of maintaining normal hippocampus function into adulthood. Therefore, this study investigated the effect of ketamine on hippocampal neurogenesis. Male Sprague-Dawley rats were divided into two groups: the control group (equal volume of normal saline), and the ketamine-anesthesia group (40 mg/kg ketamine in four injections at 1 h intervals). The S-phase marker 5-bromodeoxyuridine (BrdU) was administered after ketamine exposure to postnatal day 7 (PND-7) rats, and the neurogenesis in the hippocampal DG was assessed using single- or double-immunofluorescence staining. The expression of GFAP in the hippocampal DG was measured by western blot analysis. Spatial reference memory was tested by Morris water maze at 2 months after PND-7 rats exposed to ketamine treatment. The present results showed that neonatal ketamine exposure significantly inhibited neural stem cell (NSC) proliferation, decreased astrocytic differentiation, and markedly enhanced neuronal differentiation. The disruptive effect of ketamine on the proliferation and differentiation of NSCs lasted at least 1 week and disappeared by 2 weeks after ketamine exposure. Moreover, the migration of newborn neurons in the granule cell layer and the growth of astrocytes in the hippocampal DG were inhibited by ketamine on PND-37 and PND-44. Finally, ketamine caused a deficit in hippocampal-dependent spatial reference memory tasks at 2 months old. Our results suggested that ketamine may interfere with hippocampal neurogenesis and long-term neurocognitive function in PND-7 rats. These findings may provide a new perspective to explain the adult neurocognitive dysfunction induced by neonatal

  2. The number of neurons in specific amygdala regions is associated with boldness in mink: a study in animal personality.

    Science.gov (United States)

    Wiese, Ann-Sophie; Needham, Esther Kjær; Noer, Christina Lehmkuhl; Balsby, Thorsten Johannes Skovbjerg; Dabelsteen, Torben; Pakkenberg, Bente

    2018-01-09

    Conspecifics vary consistently in their behavioural responses towards environment stimuli such as exposure to novel objects; ethologists often refer to this variability as animal personality. The neurological mechanisms underlying animal personality traits remain largely unknown, but linking the individual variation in emotional expression to brain structural and neurochemical factors is attracting renewed interest. While considerable research has focused on hormonal and neurotransmitter effects on behavioural responses, less is known about how individual variation in the number of specific neuron populations contributes to individual variation in behaviour. The basolateral amygdala (BLA) and the central nuclei of the amygdala (CeA) mediate emotional processing by regulating behavioural responses of animals in a potentially threatening situation. As such, these structures are good candidates for evaluating the relationship between neuronal populations and behavioural traits. We now show that individual American mink (Neovison vison) reacting more boldly towards novelty have more neurons in the BLA than do their more timid conspecifics, suggesting that a developmental pattern of the number of amygdala neurons can influence behavioural traits of an adult animal. Furthermore, post hoc correlations revealed that individuals performing with higher arousal, as reflected by their frequency of startle behaviour, have more CeA neurons. Our results support a direct link between the number of neurons in amygdala regions and aspects of animal personality.

  3. Neuron Numbers in the Hypothalamus of the Normal Aging Rhesus Monkey: Stability Across the Adult Lifespan and Between the Sexes

    Science.gov (United States)

    Roberts, D.E.; Killiany, R.J.; Rosene, D.L.

    2014-01-01

    Normal aging is accompanied by changes in hypothalamic functions including autonomic and endocrine functions and circadian rhythms. The rhesus monkey provides an excellent model of normal aging without the potential confounds of incipient Alzheimer's disease inherent in human populations. This study examined the hypothalamus of 51 rhesus monkeys (23 male, 18 female, 6.5–31 years old) using design-based stereology to obtain unbiased estimates of neuron and glia numbers and the Cavalieri method to estimate volumes for eight reference spaces: total unilateral hypothalamus, suprachiasmatic nucleus (SCN), supraoptic nucleus (SON), paraventricular nucleus (PVN), dorsomedial nucleus (DM), ventromedial nucleus (VM), medial mammillary nucleus (MMN), and lateral hypothalamic area (LHA). The results demonstrated no age-related difference in neuron number, glia number, or volume in any area in either sex except the PVN of male monkeys, which showed a significant increase in both neuron and glia numbers with age. Comparison of males and females for sexual dimorphisms revealed no significant differences in neuron number. However, males had more glia overall as well as in the SCN, DM, and LHA and had a larger hypothalamic volume overall and in the SCN, SON, VM, DM, and MMN. These results demonstrate that hypothalamic neuron loss cannot account for age-related deficits in hypothalamic function and provides further evidence of the absence of neurode-generation and cell death in the normal aging rhesus monkey. PMID:21935936

  4. Autism genome-wide copy number variation reveals ubiquitin and neuronal genes.

    Science.gov (United States)

    Glessner, Joseph T; Wang, Kai; Cai, Guiqing; Korvatska, Olena; Kim, Cecilia E; Wood, Shawn; Zhang, Haitao; Estes, Annette; Brune, Camille W; Bradfield, Jonathan P; Imielinski, Marcin; Frackelton, Edward C; Reichert, Jennifer; Crawford, Emily L; Munson, Jeffrey; Sleiman, Patrick M A; Chiavacci, Rosetta; Annaiah, Kiran; Thomas, Kelly; Hou, Cuiping; Glaberson, Wendy; Flory, James; Otieno, Frederick; Garris, Maria; Soorya, Latha; Klei, Lambertus; Piven, Joseph; Meyer, Kacie J; Anagnostou, Evdokia; Sakurai, Takeshi; Game, Rachel M; Rudd, Danielle S; Zurawiecki, Danielle; McDougle, Christopher J; Davis, Lea K; Miller, Judith; Posey, David J; Michaels, Shana; Kolevzon, Alexander; Silverman, Jeremy M; Bernier, Raphael; Levy, Susan E; Schultz, Robert T; Dawson, Geraldine; Owley, Thomas; McMahon, William M; Wassink, Thomas H; Sweeney, John A; Nurnberger, John I; Coon, Hilary; Sutcliffe, James S; Minshew, Nancy J; Grant, Struan F A; Bucan, Maja; Cook, Edwin H; Buxbaum, Joseph D; Devlin, Bernie; Schellenberg, Gerard D; Hakonarson, Hakon

    2009-05-28

    Autism spectrum disorders (ASDs) are childhood neurodevelopmental disorders with complex genetic origins. Previous studies focusing on candidate genes or genomic regions have identified several copy number variations (CNVs) that are associated with an increased risk of ASDs. Here we present the results from a whole-genome CNV study on a cohort of 859 ASD cases and 1,409 healthy children of European ancestry who were genotyped with approximately 550,000 single nucleotide polymorphism markers, in an attempt to comprehensively identify CNVs conferring susceptibility to ASDs. Positive findings were evaluated in an independent cohort of 1,336 ASD cases and 1,110 controls of European ancestry. Besides previously reported ASD candidate genes, such as NRXN1 (ref. 10) and CNTN4 (refs 11, 12), several new susceptibility genes encoding neuronal cell-adhesion molecules, including NLGN1 and ASTN2, were enriched with CNVs in ASD cases compared to controls (P = 9.5 x 10(-3)). Furthermore, CNVs within or surrounding genes involved in the ubiquitin pathways, including UBE3A, PARK2, RFWD2 and FBXO40, were affected by CNVs not observed in controls (P = 3.3 x 10(-3)). We also identified duplications 55 kilobases upstream of complementary DNA AK123120 (P = 3.6 x 10(-6)). Although these variants may be individually rare, they target genes involved in neuronal cell-adhesion or ubiquitin degradation, indicating that these two important gene networks expressed within the central nervous system may contribute to the genetic susceptibility of ASD.

  5. BID Mediates Oxygen-Glucose Deprivation-Induced Neuronal Injury in Organotypic Hippocampal Slice Cultures and Modulates Tissue Inflammation in a Transient Focal Cerebral Ischemia Model without Changing Lesion Volume

    DEFF Research Database (Denmark)

    Martin, Nellie Anne; Bonner, Helena; Elkjær, Maria Louise

    2016-01-01

    deficiency protected organotypic hippocampal slice cultures in vitro from neuronal injury induced by oxygen-glucose deprivation. In vivo, BID-knockout (KO) mice and wild type (WT) mice were subjected to 60 min of transient middle cerebral artery occlusion (tMCAO) to induce focal cerebral ischemia......, and allowed to recover for 24 h. Infarct volumes and functional outcome were assessed and the inflammatory response was evaluated using immunofluorescence, Western blotting, quantitative PCR (qPCR) and Mesoscale multiplex analysis. We observed no difference in the infarct volume or neurological outcome...

  6. Changes in rat hippocampal CA1 synapses following imipramine treatment

    DEFF Research Database (Denmark)

    Chen, Fenghua; Madsen, Torsten M; Wegener, Gregers

    2008-01-01

    of synapses) in subregions of the hippocampus by quantifying number of neurons and synapses. Adult male Sprague-Dawley rats were injected with imipramine or saline (i.p.) daily for 14 days. Unbiased stereological methods were used to quantify the number of neurons and synapses. No differences in the volume...... and number of neurons of hippocampal subregions following imipramine treatment were found. However, the number and percentage of CA1 asymmetric spine synapses increased significantly and, conversely, the percentage of asymmetric shaft synapses significantly decreased in the imipramine treated group. Our...... results indicate that administration of imipramine for 14 days in normal rats could significantly increase the excitatory spine synapses, and change the relative distribution of spine and shaft synapses. We speculate that the present findings may be explained by the establishment of new synaptic...

  7. Networks of VTA Neurons Encode Real-Time Information about Uncertain Numbers of Actions Executed to Earn a Reward

    Directory of Open Access Journals (Sweden)

    Jesse Wood

    2017-08-01

    Full Text Available Multiple and unpredictable numbers of actions are often required to achieve a goal. In order to organize behavior and allocate effort so that optimal behavioral policies can be selected, it is necessary to continually monitor ongoing actions. Real-time processing of information related to actions and outcomes is typically assigned to the prefrontal cortex and basal ganglia, but also depends on midbrain regions, especially the ventral tegmental area (VTA. We were interested in how individual VTA neurons, as well as networks within the VTA, encode salient events when an unpredictable number of serial actions are required to obtain a reward. We recorded from ensembles of putative dopamine and non-dopamine neurons in the VTA as animals performed multiple cued trials in a recording session where, in each trial, serial actions were randomly rewarded. While averaging population activity did not reveal a response pattern, we observed that different neurons were selectively tuned to low, medium, or high numbered actions in a trial. This preferential tuning of putative dopamine and non-dopamine VTA neurons to different subsets of actions in a trial allowed information about binned action number to be decoded from the ensemble activity. At the network level, tuning curve similarity was positively associated with action-evoked noise correlations, suggesting that action number selectivity reflects functional connectivity within these networks. Analysis of phasic responses to cue and reward revealed that the requirement to execute multiple and uncertain numbers of actions weakens both cue-evoked responses and cue-reward response correlation. The functional connectivity and ensemble coding scheme that we observe here may allow VTA neurons to cooperatively provide a real-time account of ongoing behavior. These computations may be critical to cognitive and motivational functions that have long been associated with VTA dopamine neurons.

  8. Adult hippocampal neurogenesis in natural populations of mammals.

    Science.gov (United States)

    Amrein, Irmgard

    2015-05-01

    This review will discuss adult hippocampal neurogenesis in wild mammals of different taxa and outline similarities with and differences from laboratory animals. It begins with a review of evidence for hippocampal neurogenesis in various mammals, and shows the similar patterns of age-dependent decline in cell proliferation in wild and domesticated mammals. In contrast, the pool of immature neurons that originate from proliferative activity varies between species, implying a selective advantage for mammals that can make use of a large number of these functionally special neurons. Furthermore, rapid adaptation of hippocampal neurogenesis to experimental challenges appears to be a characteristic of laboratory rodents. Wild mammals show species-specific, rather stable hippocampal neurogenesis, which appears related to demands that characterize the niche exploited by a species rather than to acute events in the life of its members. Studies that investigate adult neurogenesis in wild mammals are not numerous, but the findings of neurogenesis under natural conditions can provide new insights, and thereby also address the question to which cognitive demands neurogenesis may respond during selection. Copyright © 2015 Cold Spring Harbor Laboratory Press; all rights reserved.

  9. Hippocampal neurogenesis and volume in migrating and wintering semipalmated sandpipers (Calidris pusilla).

    Science.gov (United States)

    de Morais Magalhães, Nara Gyzely; Guerreiro Diniz, Cristovam; Guerreiro Diniz, Daniel; Pereira Henrique, Ediely; Corrêa Pereira, Patrick Douglas; Matos Moraes, Isis Ananda; Damasceno de Melo, Mauro André; Sherry, David Francis; Wanderley Picanço Diniz, Cristovam

    2017-01-01

    Long distance migratory birds find their way by sensing and integrating information from a large number of cues in their environment. These cues are essential to navigate over thousands of kilometers and reach the same breeding, stopover, and wintering sites every year. The semipalmated sandpiper (Calidris pusilla) is a long-distance migrant that breeds in the arctic tundra of Canada and Alaska and winters on the northeast coast of South America. Its fall migration includes a 5,300-kilometer nonstop flight over the Atlantic Ocean. The avian hippocampus has been proposed to play a central role in the integration of multisensory spatial information for navigation. Hippocampal neurogenesis may contribute to hippocampal function and a variety of factors including cognitive activity, exercise, enrichment, diet and stress influence neurogenesis in the hippocampus. We quantified hippocampal neurogenesis and volume in adult migrating and wintering semipalmated sandpipers using stereological counts of doublecortin (DCX) immunolabeled immature neurons. We found that birds captured in the coastal region of Bragança, Brazil during the wintering period had more DCX positive neurons and larger volume in the hippocampus than individuals captured in the Bay of Fundy, Canada during fall migration. We also estimate the number of NeuN immunolabeled cells in migrating and wintering birds and found no significant differences between them. These findings suggest that, at this time window, neurogenesis just replaced neurons that might be lost during the transatlantic flight. Our findings also show that in active fall migrating birds, a lower level of adult hippocampal neurogenesis is associated with a smaller hippocampal formation. High levels of adult hippocampal neurogenesis and a larger hippocampal formation found in wintering birds may be late occurring effects of long distance migratory flight or the result of conditions the birds experienced while wintering.

  10. Exposure to GSM RF fields does not affect calcium homeostasis in human endothelial cells, rat pheocromocytoma cells or rat hippocampal neurons.