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Sample records for tat activates neuronal

  1. Creatine protects against mitochondrial dysfunction associated with HIV-1 Tat-induced neuronal injury

    Science.gov (United States)

    Stevens, Patrick R.; Gawryluk, Jeremy W.; Hui, Liang; Chen, Xuesong; Geiger, Jonathan D.

    2015-01-01

    HIV-1 infected individuals are living longer but experiencing a prevalence rate of over 50% for HIV-1 associated neurocognitive disorders (HAND) for which no effective treatment is available. Viral and cellular factors secreted by HIV-1 infected cells leads to neuronal injury and HIV-1 Tat continues to be implicated in the pathogenesis of HAND. Here we tested the hypothesis that creatine protected against HIV-1 Tat-induced neuronal injury by preventing mitochondrial bioenergetic crisis and/or redox catastrophe. Creatine blocked HIV-1 Tat1-72-induced increases in neuron cell death and synaptic area loss. Creatine protected against HIV-1 Tat-induced decreases in ATP. Creatine and creatine plus HIV-1 Tat increased cellular levels of creatine, and creatine plus HIV-1 Tat further decreased ratios of phosphocreatine to creatine observed with creatine or HIV-1 Tat treatments alone. Additionally, creatine protected against HIV-1 Tat-induced mitochondrial hypopolarization and HIV-1 Tat-induced mitochondrial permeability transition pore opening. Thus, creatine may be a useful adjunctive therapy against HAND. PMID:25613139

  2. PSD-95 uncoupling from NMDA receptors by Tat-N-dimer ameliorates neuronal depolarisation in cortical spreading depression

    DEFF Research Database (Denmark)

    Kucharz, Krzysztof; Søndergaard Rasmussen, Ida; Bach, Anders

    2017-01-01

    during the first hour after i.v. injection. The Tat-N-dimer suppressed stimulation-evoked synaptic activity by 2-20%, while cortical blood flow and cerebral oxygen metabolic (CMRO2) responses were preserved. During cortical spreading depression, the Tat-N-dimer reduced the average amplitude...... depression on cortical blood flow and CMRO2 We suggest that uncoupling of PSD-95 from NMDA receptors reduces overall neuronal excitability and the amplitude of the spreading depolarisation wave. These findings may be of interest for understanding the neuroprotective effects of the nNOS/PSD-95 uncoupling...

  3. Direct effects of HIV-1 Tat on excitability and survival of primary dorsal root ganglion neurons: possible contribution to HIV-1-associated pain.

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    Xianxun Chi

    Full Text Available The vast majority of people living with human immunodeficiency virus type 1 (HIV-1 have pain syndrome, which has a significant impact on their quality of life. The underlying causes of HIV-1-associated pain are not likely attributable to direct viral infection of the nervous system due to the lack of evidence of neuronal infection by HIV-1. However, HIV-1 proteins are possibly involved as they have been implicated in neuronal damage and death. The current study assesses the direct effects of HIV-1 Tat, one of potent neurotoxic viral proteins released from HIV-1-infected cells, on the excitability and survival of rat primary dorsal root ganglion (DRG neurons. We demonstrated that HIV-1 Tat triggered rapid and sustained enhancement of the excitability of small-diameter rat primary DRG neurons, which was accompanied by marked reductions in the rheobase and resting membrane potential (RMP, and an increase in the resistance at threshold (R(Th. Such Tat-induced DRG hyperexcitability may be a consequence of the inhibition of cyclin-dependent kinase 5 (Cdk5 activity. Tat rapidly inhibited Cdk5 kinase activity and mRNA production, and roscovitine, a well-known Cdk5 inhibitor, induced a very similar pattern of DRG hyperexcitability. Indeed, pre-application of Tat prevented roscovitine from having additional effects on the RMP and action potentials (APs of DRGs. However, Tat-mediated actions on the rheobase and R(Th were accelerated by roscovitine. These results suggest that Tat-mediated changes in DRG excitability are partly facilitated by Cdk5 inhibition. In addition, Cdk5 is most abundant in DRG neurons and participates in the regulation of pain signaling. We also demonstrated that HIV-1 Tat markedly induced apoptosis of primary DRG neurons after exposure for longer than 48 h. Together, this work indicates that HIV-1 proteins are capable of producing pain signaling through direct actions on excitability and survival of sensory neurons.

  4. The HIV-1 transcriptional activator Tat has potent nucleic acid chaperoning activities in vitro.

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    Kuciak, Monika; Gabus, Caroline; Ivanyi-Nagy, Roland; Semrad, Katharina; Storchak, Roman; Chaloin, Olivier; Muller, Sylviane; Mély, Yves; Darlix, Jean-Luc

    2008-06-01

    The human immunodeficiency virus type 1 (HIV-1) is a primate lentivirus that causes the acquired immunodeficiency syndrome (AIDS). In addition to the virion structural proteins and enzyme precursors, that are Gag, Env and Pol, HIV-1 encodes several regulatory proteins, notably a small nuclear transcriptional activator named Tat. The Tat protein is absolutely required for virus replication since it controls proviral DNA transcription to generate the full-length viral mRNA. Tat can also regulate mRNA capping and splicing and was recently found to interfere with the cellular mi- and siRNA machinery. Because of its extensive interplay with nucleic acids, and its basic and disordered nature we speculated that Tat had nucleic acid-chaperoning properties. This prompted us to examine in vitro the nucleic acid-chaperoning activities of Tat and Tat peptides made by chemical synthesis. Here we report that Tat has potent nucleic acid-chaperoning activities according to the standard DNA annealing, DNA and RNA strand exchange, RNA ribozyme cleavage and trans-splicing assays. The active Tat(44-61) peptide identified here corresponds to the smallest known sequence with DNA/RNA chaperoning properties.

  5. Systematic Analysis of the Functions of Lysine Acetylation in the Regulation of Tat Activity.

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    Minghao He

    Full Text Available The Tat protein of HIV-1 has several well-known properties, such as nucleocytoplasmic trafficking, transactivation of transcription, interaction with tubulin, regulation of mitotic progression, and induction of apoptosis. Previous studies have identified a couple of lysine residues in Tat that are essential for its functions. In order to analyze the functions of all the lysine residues in Tat, we mutated them individually to alanine, glutamine, and arginine. Through systematic analysis of the lysine mutants, we discovered several previously unidentified characteristics of Tat. We found that lysine acetylation could modulate the subcellular localization of Tat, in addition to the regulation of its transactivation activity. Our data also revealed that lysine mutations had distinct effects on microtubule assembly and Tat binding to bromodomain proteins. By correlation analysis, we further found that the effects of Tat on apoptosis and mitotic progression were not entirely attributed to its effect on microtubule assembly. Our findings suggest that Tat may regulate diverse cellular activities through binding to different proteins and that the acetylation of distinct lysine residues in Tat may modulate its interaction with various partners.

  6. Fractalkine/CX3CL1 protects striatal neurons from synergistic morphine and HIV-1 Tat-induced dendritic losses and death

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    Suzuki Masami

    2011-11-01

    Full Text Available Abstract Background Fractalkine/CX3CL1 and its cognate receptor CX3CR1 are abundantly expressed in the CNS. Fractalkine is an unusual C-X3-C motif chemokine that is important in neuron-microglial communication, a co-receptor for HIV infection, and can be neuroprotective. To assess the effects of fractalkine on opiate-HIV interactive neurotoxicity, wild-type murine striatal neurons were co-cultured with mixed glia from the striata of wild-type or Cx3cr1 knockout mice ± HIV-1 Tat and/or morphine. Time-lapse digital images were continuously recorded at 20 min intervals for up to 72 h using computer-aided microscopy to track the same cells repeatedly. Results Co-exposure to Tat and morphine caused synergistic increases in neuron death, dendritic pruning, and microglial motility as previously reported. Exogenous fractalkine prevented synergistic Tat and morphine-induced dendritic losses and neuron death even though the inflammatory mediator TNF-α remained significantly elevated. Antibody blockade of CX3CR1 mimicked the toxic effects of morphine plus Tat, but did not add to their toxicity; while fractalkine failed to protect wild-type neurons co-cultured with Cx3cr1-/--null glia against morphine and Tat toxicity. Exogenous fractalkine also normalized microglial motility, which is elevated by Tat and morphine co-exposure, presumably limiting microglial surveillance that may lead to toxic effects on neurons. Fractalkine immunofluorescence was expressed in neurons and to a lesser extent by other cell types, whereas CX3CR1 immunoreactivity or GFP fluorescence in cells cultured from the striatum of Cx3cr1-/- (Cx3cr1GFP/GFP mice were associated with microglia. Immunoblotting shows that fractalkine levels were unchanged following Tat and/or morphine exposure and there was no increase in released fractalkine as determined by ELISA. By contrast, CX3CR1 protein levels were markedly downregulated. Conclusions The results suggest that deficits in fractalkine

  7. Controlling cellular P-TEFb activity by the HIV-1 transcriptional transactivator Tat.

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    Lisa Muniz

    Full Text Available The human immunodeficiency virus 1 (HIV-1 transcriptional transactivator (Tat is essential for synthesis of full-length transcripts from the integrated viral genome by RNA polymerase II (Pol II. Tat recruits the host positive transcription elongation factor b (P-TEFb to the HIV-1 promoter through binding to the transactivator RNA (TAR at the 5'-end of the nascent HIV transcript. P-TEFb is a general Pol II transcription factor; its cellular activity is controlled by the 7SK small nuclear RNA (snRNA and the HEXIM1 protein, which sequester P-TEFb into transcriptionally inactive 7SK/HEXIM/P-TEFb snRNP. Besides targeting P-TEFb to HIV transcription, Tat also increases the nuclear level of active P-TEFb through promoting its dissociation from the 7SK/HEXIM/P-TEFb RNP by an unclear mechanism. In this study, by using in vitro and in vivo RNA-protein binding assays, we demonstrate that HIV-1 Tat binds with high specificity and efficiency to an evolutionarily highly conserved stem-bulge-stem motif of the 5'-hairpin of human 7SK snRNA. The newly discovered Tat-binding motif of 7SK is structurally and functionally indistinguishable from the extensively characterized Tat-binding site of HIV TAR and importantly, it is imbedded in the HEXIM-binding elements of 7SK snRNA. We show that Tat efficiently replaces HEXIM1 on the 7SK snRNA in vivo and therefore, it promotes the disassembly of the 7SK/HEXIM/P-TEFb negative transcriptional regulatory snRNP to augment the nuclear level of active P-TEFb. This is the first demonstration that HIV-1 specifically targets an important cellular regulatory RNA, most probably to promote viral transcription and replication. Demonstration that the human 7SK snRNA carries a TAR RNA-like Tat-binding element that is essential for the normal transcriptional regulatory function of 7SK questions the viability of HIV therapeutic approaches based on small drugs blocking the Tat-binding site of HIV TAR.

  8. Deciphering structure-activity relationships in a series of Tat/TAR inhibitors.

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    Pascale, Lise; González, Alejandro López; Di Giorgio, Audrey; Gaysinski, Marc; Teixido Closa, Jordi; Tejedor, Roger Estrada; Azoulay, Stéphane; Patino, Nadia

    2016-11-01

    A series of pentameric "Polyamide Amino Acids" (PAAs) compounds derived from the same trimeric precursor have been synthesized and investigated as HIV TAR RNA ligands, in the absence and in the presence of a Tat fragment. All PAAs bind TAR with similar sub-micromolar affinities but their ability to compete efficiently with the Tat fragment strongly differs, IC50 ranging from 35 nM to >2 μM. While NMR and CD studies reveal that all PAA interact with TAR at the same site and induce globally the same RNA conformational change upon binding, a comparative thermodynamic study of PAA/TAR equilibria highlights distinct TAR binding modes for Tat competitor and non-competitor PAAs. This led us to suggest two distinct interaction modes that have been further validated by molecular modeling studies. While the binding of Tat competitor PAAs induces a contraction at the TAR bulge region, the binding of non-competitor ones widens it. This could account for the distinct PAA ability to compete with Tat fragment. Our work illustrates how comparative thermodynamic studies of a series of RNA ligands of same chemical family are of value for understanding their binding modes and for rationalizing structure-activity relationships.

  9. The neuroprotective efficacy of cell-penetrating peptides TAT, penetratin, Arg-9, and Pep-1 in glutamic acid, kainic acid, and in vitro ischemia injury models using primary cortical neuronal cultures.

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    Meloni, Bruno P; Craig, Amanda J; Milech, Nadia; Hopkins, Richard M; Watt, Paul M; Knuckey, Neville W

    2014-03-01

    Cell-penetrating peptides (CPPs) are small peptides (typically 5-25 amino acids), which are used to facilitate the delivery of normally non-permeable cargos such as other peptides, proteins, nucleic acids, or drugs into cells. However, several recent studies have demonstrated that the TAT CPP has neuroprotective properties. Therefore, in this study, we assessed the TAT and three other CPPs (penetratin, Arg-9, Pep-1) for their neuroprotective properties in cortical neuronal cultures following exposure to glutamic acid, kainic acid, or in vitro ischemia (oxygen-glucose deprivation). Arg-9, penetratin, and TAT-D displayed consistent and high level neuroprotective activity in both the glutamic acid (IC50: 0.78, 3.4, 13.9 μM) and kainic acid (IC50: 0.81, 2.0, 6.2 μM) injury models, while Pep-1 was ineffective. The TAT-D isoform displayed similar efficacy to the TAT-L isoform in the glutamic acid model. Interestingly, Arg-9 was the only CPP that displayed efficacy when washed-out prior to glutamic acid exposure. Neuroprotection following in vitro ischemia was more variable with all peptides providing some level of neuroprotection (IC50; Arg-9: 6.0 μM, TAT-D: 7.1 μM, penetratin/Pep-1: >10 μM). The positive control peptides JNKI-1D-TAT (JNK inhibitory peptide) and/or PYC36L-TAT (AP-1 inhibitory peptide) were neuroprotective in all models. Finally, in a post-glutamic acid treatment experiment, Arg-9 was highly effective when added immediately after, and mildly effective when added 15 min post-insult, while the JNKI-1D-TAT control peptide was ineffective when added post-insult. These findings demonstrate that different CPPs have the ability to inhibit neurodamaging events/pathways associated with excitotoxic and ischemic injuries. More importantly, they highlight the need to interpret neuroprotection studies when using CPPs as delivery agents with caution. On a positive note, the cytoprotective properties of CPPs suggests they are ideal carrier molecules to

  10. Contribution of nonneutralizing vaccine-elicited antibody activities to improved protective efficacy in rhesus macaques immunized with Tat/Env compared with multigenic vaccines.

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    Florese, Ruth H; Demberg, Thorsten; Xiao, Peng; Kuller, LaRene; Larsen, Kay; Summers, L Ebonita; Venzon, David; Cafaro, Aurelio; Ensoli, Barbara; Robert-Guroff, Marjorie

    2009-03-15

    Previously, chronic-phase protection against SHIV(89.6P) challenge was significantly greater in macaques primed with replicating adenovirus type 5 host range mutant (Ad5hr) recombinants encoding HIVtat and env and boosted with Tat and Env protein compared with macaques primed with multigenic adenovirus recombinants (HIVtat, HIVenv, SIVgag, SIVnef) and boosted with Tat, Env, and Nef proteins. The greater protection was correlated with Tat- and Env-binding Abs. Because the macaques lacked SHIV(89.6P)-neutralizing activity prechallenge, we investigated whether Ab-dependent cellular cytotoxicity (ADCC) and Ab-dependent cell-mediated viral inhibition (ADCVI) might exert a protective effect. We clearly show that Tat can serve as an ADCC target, although the Tat-specific activity elicited did not correlate with better protection. However, Env-specific ADCC activity was consistently higher in the Tat/Env group, with sustained cell killing postchallenge exhibited at higher levels (p vaccine regimens.

  11. Human Immunodeficiency Virus Tat-Activated Expression of Poliovirus Protein 2A Inhibits mRNA Translation

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    Sun, Xiao-Hong; Baltimore, David

    1989-04-01

    To study the effect of poliovirus protein 2A on cellular RNA translation, the tat control system of human immunodeficiency virus (HIV) was used. Protein 2A was expressed from a plasmid construct (pHIV/2A) incorporating the HIV long terminal repeat. Protein synthesis was measured by using chloramphenicol acetyltransferase as a reporter gene driven by the Rous sarcoma virus long terminal repeat. When HIV/2A was contransfected with the reporter, addition of a tat-producing plasmid caused at least a 50-fold drop in chloramphenicol acetyltransferase synthesis. A HeLa cell line carrying HIV/2A was established. In it, tat expression caused more than a 10-fold drop in chloramphenicol acetyltransferase synthesis from the reporter plasmid. Furthermore, 2A induction by tat caused cleavage of the cellular translation factor P220, a part of eukaryotic translation initiation factor 4F. Thus protein 2A can, by itself, carry out the inhibition of cellular protein synthesis characteristic of a poliovirus infection. Also, the HIV tat activation provides a very effective method to control gene expression in mammalian cells.

  12. 海马神经元中TAT-GluR6-9c-dansyl小肽的荧光观察%Delivery of GluR6-9c into hippocampal neurons by TAT transduction domain

    Institute of Scientific and Technical Information of China (English)

    纵艳艳; 裴冬生; 孙亚峰; 张光毅

    2005-01-01

    目的研究TAT-GluR6-9c-dansyl荧光小肽是否可以进入细胞内部.方法在培养的海马神经元中加入TAT-GluR6-9c-dansyl荧光小肽和对照肽TAT38-48-dansyl.结果用10 μmol/L TAT-GluR6-9c-dansyl处理的海马神经元在荧光显微镜下可以观到绿色荧光的出现,而对照肽TAT38-48-dansyl无荧光出现.结论 TAT-GluR6-9c-dansyl荧光小肽可以进入细胞.

  13. Tat-CBR1 inhibits inflammatory responses through the suppressions of NF-κB and MAPK activation in macrophages and TPA-induced ear edema in mice

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Young Nam [Department of Biomedical Science and Research Institute of Bioscience and Biotechnology, Hallym University, Chunchon 200-702 (Korea, Republic of); Kim, Dae Won [Department of Biochemistry and Molecular Biology, Research Institute of Oral Sciences, College of Dentistry, Kangnung-Wonju National University, Kangneung 210-702 (Korea, Republic of); Jo, Hyo Sang; Shin, Min Jea; Ahn, Eun Hee; Ryu, Eun Ji; Yong, Ji In; Cha, Hyun Ju; Kim, Sang Jin; Yeo, Hyeon Ji; Youn, Jong Kyu; Hwang, Jae Hyeok [Department of Biomedical Science and Research Institute of Bioscience and Biotechnology, Hallym University, Chunchon 200-702 (Korea, Republic of); Jeong, Ji-Heon; Kim, Duk-Soo [Department of Anatomy, College of Medicine, Soonchunhyang University, Cheonan-Si 330-090 (Korea, Republic of); Cho, Sung-Woo [Department of Biochemistry and Molecular Biology, University of Ulsan College of Medicine, Seoul 138-736 (Korea, Republic of); Park, Jinseu [Department of Biomedical Science and Research Institute of Bioscience and Biotechnology, Hallym University, Chunchon 200-702 (Korea, Republic of); Eum, Won Sik, E-mail: wseum@hallym.ac.kr [Department of Biomedical Science and Research Institute of Bioscience and Biotechnology, Hallym University, Chunchon 200-702 (Korea, Republic of); Choi, Soo Young, E-mail: sychoi@hallym.ac.kr [Department of Biomedical Science and Research Institute of Bioscience and Biotechnology, Hallym University, Chunchon 200-702 (Korea, Republic of)

    2015-07-15

    Human carbonyl reductase 1 (CBR1) plays a crucial role in cell survival and protects against oxidative stress response. However, its anti-inflammatory effects are not yet clearly understood. In this study, we examined whether CBR1 protects against inflammatory responses in macrophages and mice using a Tat-CBR1 protein which is able to penetrate into cells. The results revealed that purified Tat-CBR1 protein efficiently transduced into Raw 264.7 cells and inhibited lipopolysaccharide (LPS)-induced cyclooxygenase-2 (COX-2), nitric oxide (NO) and prostaglandin E{sub 2} (PGE{sub 2}) expression levels. In addition, Tat-CBR1 protein leads to decreased pro-inflammatory cytokine expression through suppression of nuclear transcription factor-kappaB (NF-κB) and mitogen activated protein kinase (MAPK) activation. Furthermore, Tat-CBR1 protein inhibited inflammatory responses in 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced skin inflammation when applied topically. These findings indicate that Tat-CBR1 protein has anti-inflammatory properties in vitro and in vivo through inhibition of NF-κB and MAPK activation, suggesting that Tat-CBR1 protein may have potential as a therapeutic agent against inflammatory diseases. - Highlights: • Transduced Tat-CBR1 reduces LPS-induced inflammatory mediators and cytokines. • Tat-CBR1 inhibits MAPK and NF-κB activation. • Tat-CBR1 ameliorates inflammation response in vitro and in vivo. • Tat-CBR1 may be useful as potential therapeutic agent for inflammation.

  14. Energy Model of Neuron Activation.

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    Romanyshyn, Yuriy; Smerdov, Andriy; Petrytska, Svitlana

    2017-02-01

    On the basis of the neurophysiological strength-duration (amplitude-duration) curve of neuron activation (which relates the threshold amplitude of a rectangular current pulse of neuron activation to the pulse duration), as well as with the use of activation energy constraint (the threshold curve corresponds to the energy threshold of neuron activation by a rectangular current pulse), an energy model of neuron activation by a single current pulse has been constructed. The constructed model of activation, which determines its spectral properties, is a bandpass filter. Under the condition of minimum-phase feature of the neuron activation model, on the basis of Hilbert transform, the possibilities of phase-frequency response calculation from its amplitude-frequency response have been considered. Approximation to the amplitude-frequency response by the response of the Butterworth filter of the first order, as well as obtaining the pulse response corresponding to this approximation, give us the possibility of analyzing the efficiency of activating current pulses of various shapes, including analysis in accordance with the energy constraint.

  15. Assessment of the chemosensitizing activity of TAT-RasGAP317-326 in childhood cancers.

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    Nadja Chevalier

    Full Text Available Although current anti-cancer protocols are reasonably effective, treatment-associated long-term side effects, induced by lack of specificity of the anti-cancer procedures, remain a challenging problem in pediatric oncology. TAT-RasGAP317-326 is a RasGAP-derived cell-permeable peptide that acts as a sensitizer to various anti-cancer treatments in adult tumor cells. In the present study, we assessed the effect of TAT-RasGAP317-326 in several childhood cancer cell lines. The RasGAP-derived peptide-induced cell death was analyzed in several neuroblastoma, Ewing sarcoma and leukemia cell lines (as well as in normal lymphocytes. Cell death was evaluated using flow cytometry methods in the absence or in the presence of the peptide in combination with various genotoxins used in the clinics (4-hydroperoxycyclophosphamide, etoposide, vincristine and doxorubicin. All tested pediatric tumors, in response to at least one genotoxin, were sensitized by TAT-RasGAP317-326. The RasGAP-derived peptide did not increase cell death of normal lymphocytes, alone or in combination with the majority of the tested chemotherapies. Consequently, TAT-RasGAP317-326 may benefit children with tumors by increasing the efficacy of anti-cancer therapies notably by allowing reductions in anti-cancer drug dosage and the associated drug-induced side effects.

  16. Effects of x-rays or aseptic inflammatory reaction on the circadian rythm of tyrosine aminotransferase in mouse liver (TAT activity of mouse liver)

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    Jungowska-Klin, B.

    1979-01-01

    The circadian rhythm of tyrosine aminotransferase (TAT) was investigated during 48 hours in the liver of mice subjected to: a/ subcutaneous inflammatory reaction, b/ ionizing radiation. The cyclic changes in the circadian enzyme activity were described with a harmonic function. In relation to the control mice in the experimental mice statistically significant changes were demonstrated in the activity of tyrosine aminotransferase associated with desynchronization of the circadian TAT rhythm, particularly evident in the first hours of the first day of the experiment. The functions of enzyme activity changed in the second 24-hours period showed, both qualitatively and quantitatively, a tendency for a gradual return of normal TAT activity in the 24-hour periods. (author)

  17. HIV-1 TAT protein enhances sensitization to methamphetamine by affecting dopaminergic function.

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    Kesby, James P; Najera, Julia A; Romoli, Benedetto; Fang, Yiding; Basova, Liana; Birmingham, Amanda; Marcondes, Maria Cecilia G; Dulcis, Davide; Semenova, Svetlana

    2017-10-01

    Methamphetamine abuse is common among humans with immunodeficiency virus (HIV). The HIV-1 regulatory protein TAT induces dysfunction of mesolimbic dopaminergic systems which may result in impaired reward processes and contribute to methamphetamine abuse. These studies investigated the impact of TAT expression on methamphetamine-induced locomotor sensitization, underlying changes in dopamine function and adenosine receptors in mesolimbic brain areas and neuroinflammation (microgliosis). Transgenic mice with doxycycline-induced TAT protein expression in the brain were tested for locomotor activity in response to repeated methamphetamine injections and methamphetamine challenge after a 7-day abstinence period. Dopamine function in the nucleus accumbens (Acb) was determined using high performance liquid chromatography. Expression of dopamine and/or adenosine A receptors (ADORA) in the Acb and caudate putamen (CPu) was assessed using RT-PCR and immunohistochemistry analyses. Microarrays with pathway analyses assessed dopamine and adenosine signaling in the CPu. Activity-dependent neurotransmitter switching of a reserve pool of non-dopaminergic neurons to a dopaminergic phenotype in the ventral tegmental area (VTA) was determined by immunohistochemistry and quantified with stereology. TAT expression enhanced methamphetamine-induced sensitization. TAT expression alone decreased striatal dopamine (D1, D2, D4, D5) and ADORA1A receptor expression, while increasing ADORA2A receptors expression. Moreover, TAT expression combined with methamphetamine exposure was associated with increased adenosine A receptors (ADORA1A) expression and increased recruitment of dopamine neurons in the VTA. TAT expression and methamphetamine exposure induced microglia activation with the largest effect after combined exposure. Our findings suggest that dopamine-adenosine receptor interactions and reserve pool neuronal recruitment may represent potential targets to develop new treatments for

  18. LRRK2 kinase inhibition prevents pathological microglial phagocytosis in response to HIV-1 Tat protein

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    Marker Daniel F

    2012-11-01

    Full Text Available Abstract Background Human Immunodeficiency Virus-1 (HIV-1 associated neurocognitive disorders (HANDs are accompanied by significant morbidity, which persists despite the use of combined antiretroviral therapy (cART. While activated microglia play a role in pathogenesis, changes in their immune effector functions, including phagocytosis and proinflammatory signaling pathways, are not well understood. We have identified leucine-rich repeat kinase 2 (LRRK2 as a novel regulator of microglial phagocytosis and activation in an in vitro model of HANDs, and hypothesize that LRRK2 kinase inhibition will attenuate microglial activation during HANDs. Methods We treated BV-2 immortalized mouse microglia cells with the HIV-1 trans activator of transcription (Tat protein in the absence or presence of LRRK2 kinase inhibitor (LRRK2i. We used Western blot, qRT-PCR, immunocytochemistry and latex bead engulfment assays to analyze LRRK2 protein levels, proinflammatory cytokine and phagocytosis receptor expression, LRRK2 cellular distribution and phagocytosis, respectively. Finally, we utilized ex vivo microfluidic chambers containing primary hippocampal neurons and BV-2 microglia cells to investigate microglial phagocytosis of neuronal axons. Results We found that Tat-treatment of BV-2 cells induced kinase activity associated phosphorylation of serine 935 on LRRK2 and caused the formation of cytoplasmic LRRK2 inclusions. LRRK2i decreased Tat-induced phosphorylation of serine 935 on LRRK2 and inhibited the formation of Tat-induced cytoplasmic LRRK2 inclusions. LRRK2i also decreased Tat-induced process extension in BV-2 cells. Furthermore, LRRK2i attenuated Tat-induced cytokine expression and latex bead engulfment. We examined relevant cellular targets in microfluidic chambers and found that Tat-treated BV-2 microglia cells cleared axonal arbor and engulfed neuronal elements, whereas saline treated controls did not. LRRK2i was found to protect axons in the presence

  19. Npas4: Linking Neuronal Activity to Memory.

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    Sun, Xiaochen; Lin, Yingxi

    2016-04-01

    Immediate-early genes (IEGs) are rapidly activated after sensory and behavioral experience and are believed to be crucial for converting experience into long-term memory. Neuronal PAS domain protein 4 (Npas4), a recently discovered IEG, has several characteristics that make it likely to be a particularly important molecular link between neuronal activity and memory: it is among the most rapidly induced IEGs, is expressed only in neurons, and is selectively induced by neuronal activity. By orchestrating distinct activity-dependent gene programs in different neuronal populations, Npas4 affects synaptic connections in excitatory and inhibitory neurons, neural circuit plasticity, and memory formation. It may also be involved in circuit homeostasis through negative feedback and psychiatric disorders. We summarize these findings and discuss their implications. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Glutamate mediated astrocytic filtering of neuronal activity.

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    Gilad Wallach

    2014-12-01

    Full Text Available Neuron-astrocyte communication is an important regulatory mechanism in various brain functions but its complexity and role are yet to be fully understood. In particular, the temporal pattern of astrocyte response to neuronal firing has not been fully characterized. Here, we used neuron-astrocyte cultures on multi-electrode arrays coupled to Ca2+ imaging and explored the range of neuronal stimulation frequencies while keeping constant the amount of stimulation. Our results reveal that astrocytes specifically respond to the frequency of neuronal stimulation by intracellular Ca2+ transients, with a clear onset of astrocytic activation at neuron firing rates around 3-5 Hz. The cell-to-cell heterogeneity of the astrocyte Ca2+ response was however large and increasing with stimulation frequency. Astrocytic activation by neurons was abolished with antagonists of type I metabotropic glutamate receptor, validating the glutamate-dependence of this neuron-to-astrocyte pathway. Using a realistic biophysical model of glutamate-based intracellular calcium signaling in astrocytes, we suggest that the stepwise response is due to the supralinear dynamics of intracellular IP3 and that the heterogeneity of the responses may be due to the heterogeneity of the astrocyte-to-astrocyte couplings via gap junction channels. Therefore our results present astrocyte intracellular Ca2+ activity as a nonlinear integrator of glutamate-dependent neuronal activity.

  1. Glutamate Mediated Astrocytic Filtering of Neuronal Activity

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    Herzog, Nitzan; De Pittà, Maurizio; Jacob, Eshel Ben; Berry, Hugues; Hanein, Yael

    2014-01-01

    Neuron-astrocyte communication is an important regulatory mechanism in various brain functions but its complexity and role are yet to be fully understood. In particular, the temporal pattern of astrocyte response to neuronal firing has not been fully characterized. Here, we used neuron-astrocyte cultures on multi-electrode arrays coupled to Ca2+ imaging and explored the range of neuronal stimulation frequencies while keeping constant the amount of stimulation. Our results reveal that astrocytes specifically respond to the frequency of neuronal stimulation by intracellular Ca2+ transients, with a clear onset of astrocytic activation at neuron firing rates around 3-5 Hz. The cell-to-cell heterogeneity of the astrocyte Ca2+ response was however large and increasing with stimulation frequency. Astrocytic activation by neurons was abolished with antagonists of type I metabotropic glutamate receptor, validating the glutamate-dependence of this neuron-to-astrocyte pathway. Using a realistic biophysical model of glutamate-based intracellular calcium signaling in astrocytes, we suggest that the stepwise response is due to the supralinear dynamics of intracellular IP3 and that the heterogeneity of the responses may be due to the heterogeneity of the astrocyte-to-astrocyte couplings via gap junction channels. Therefore our results present astrocyte intracellular Ca2+ activity as a nonlinear integrator of glutamate-dependent neuronal activity. PMID:25521344

  2. Tat-dependent repression of human immunodeficiency virus type 1 long terminal repeat promoter activity by fusion of cellular transcription factors

    International Nuclear Information System (INIS)

    Zhao Cunyou; Chen Yali; Park, Jiyoung; Kim, Jae Bum; Tang Hong

    2004-01-01

    Transcription initiation from HIV-1 long terminal repeat (LTR) promoter requires the virally encoded transactivator, Tat, and several cellular co-factors to accomplish the Tat-dependent processive transcription elongation. Individual cellular transcription activators, LBP-1b and Oct-1, on the other hand, have been shown to inhibit LTR promoter activities probably via competitive binding against TFIID to the TATA-box in LTR promoter. To explore the genetic interference strategies against the viral replication, we took advantage of the existence of the bipartite DNA binding domains and the repression domains of LBP-1b and Oct-1 factors to generate a chimeric transcription repressor. Our results indicated that the fusion protein of LBP-1b and Oct-1 exhibited higher DNA binding affinity to the viral promoter than the individual factors, and little interference with the host cell gene expression due to its anticipated rare cognate DNA sites in the host cell genome. Moreover, the chimera exerted increased Tat-dependent repression of transcription initiation at the LTR promoter both in vitro and in vivo compared to LBP-1b, Oct-1 or combination of LBP-1b and Oct-1. These results might provide the lead in generating a therapeutic reagent useful to suppress HIV-1 replication

  3. Tat-antioxidant 1 protects against stress-induced hippocampal HT-22 cells death and attenuate ischaemic insult in animal model.

    Science.gov (United States)

    Kim, So Mi; Hwang, In Koo; Yoo, Dae Young; Eum, Won Sik; Kim, Dae Won; Shin, Min Jea; Ahn, Eun Hee; Jo, Hyo Sang; Ryu, Eun Ji; Yong, Ji In; Cho, Sung-Woo; Kwon, Oh-Shin; Lee, Keun Wook; Cho, Yoon Shin; Han, Kyu Hyung; Park, Jinseu; Choi, Soo Young

    2015-06-01

    Oxidative stress-induced reactive oxygen species (ROS) are responsible for various neuronal diseases. Antioxidant 1 (Atox1) regulates copper homoeostasis and promotes cellular antioxidant defence against toxins generated by ROS. The roles of Atox1 protein in ischaemia, however, remain unclear. In this study, we generated a protein transduction domain fused Tat-Atox1 and examined the roles of Tat-Atox1 in oxidative stress-induced hippocampal HT-22 cell death and an ischaemic injury animal model. Tat-Atox1 effectively transduced into HT-22 cells and it protected cells against the effects of hydrogen peroxide (H2O2)-induced toxicity including increasing of ROS levels and DNA fragmentation. At the same time, Tat-Atox1 regulated cellular survival signalling such as p53, Bad/Bcl-2, Akt and mitogen-activate protein kinases (MAPKs). In the animal ischaemia model, transduced Tat-Atox1 protected against neuronal cell death in the hippocampal CA1 region. In addition, Tat-Atox1 significantly decreased the activation of astrocytes and microglia as well as lipid peroxidation in the CA1 region after ischaemic insult. Taken together, these results indicate that transduced Tat-Atox1 protects against oxidative stress-induced HT-22 cell death and against neuronal damage in animal ischaemia model. Therefore, we suggest that Tat-Atox1 has potential as a therapeutic agent for the treatment of oxidative stress-induced ischaemic damage. © 2015 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

  4. Extensive interactions between HIV TAT and TAF(II)250.

    Science.gov (United States)

    Weissman, J D; Hwang, J R; Singer, D S

    2001-03-09

    The HIV transactivator, Tat, has been shown to be capable of potent repression of transcription initiation. Repression is mediated by the C-terminal segment of Tat, which binds the TFIID component, TAF(II)250, although the site(s) of interaction were not defined previously. We now report that the interaction between Tat and TAF(II)250 is extensive and involves multiple contacts between the Tat protein and TAF(II)250. The C-terminal domain of Tat, which is necessary for repression of transcription initiation, binds to a segment of TAF(II)250 that encompasses its acetyl transferase (AT) domain (885-1034 amino acids (aa)). Surprisingly, the N-terminal segment of Tat, which contains its activation domains, also binds to TAF(II)250 and interacts with two discontinuous segments of TAF(II)250 located between 885 and 984 aa and 1120 and 1279 aa. Binding of Tat to the 885-984 aa segment of TAF(II)250 requires the cysteine-rich domain of Tat, but not the acidic or glutamine-rich domains. Binding by the N-terminal domain of Tat to the 1120-1279 aa TAF(II)250 segment does not involve the acidic, cysteine- or glutamine-rich domains. Repression of transcription initiation by Tat requires functional TAF(II)250. We now demonstrate that transcription of the HIV LTR does not depend on TAF(II)250 which may account for its resistance to Tat mediated repression.

  5. Resveratrol stimulates AMP kinase activity in neurons.

    Science.gov (United States)

    Dasgupta, Biplab; Milbrandt, Jeffrey

    2007-04-24

    Resveratrol is a polyphenol produced by plants that has multiple beneficial activities similar to those associated with caloric restriction (CR), such as increased life span and delay in the onset of diseases associated with aging. CR improves neuronal health, and the global beneficial effects of CR have been postulated to be mediated by the nervous system. One key enzyme thought to be activated during CR is the AMP-activated kinase (AMPK), a sensor of cellular energy levels. AMPK is activated by increases in the cellular AMP:ATP ratio, whereupon it functions to help preserve cellular energy. In this regard, the regulation of dietary food intake by hypothalamic neurons is mediated by AMPK. The suppression of nonessential energy expenditure by activated AMPK along with the CR mimetic and neuroprotective properties of resveratrol led us to hypothesize that neuronal activation of AMPK could be an important component of resveratrol activity. Here, we show that resveratrol activated AMPK in Neuro2a cells and primary neurons in vitro as well as in the brain. Resveratrol and the AMPK-activating compound 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside (AICAR) promoted robust neurite outgrowth in Neuro2a cells, which was blocked by genetic and pharmacologic inhibition of AMPK. Resveratrol also stimulated mitochondrial biogenesis in an AMPK-dependent manner. Resveratrol-stimulated AMPK activity in neurons depended on LKB1 activity but did not require the NAD-dependent protein deacetylase SIRT1 during this time frame. These findings suggest that neuronal activation of AMPK by resveratrol could affect neuronal energy homeostasis and contribute to the neuroprotective effects of resveratrol.

  6. Trans-activation of the JC virus late promoter by the tat protein of type 1 human immunodeficiency virus in glial cells

    International Nuclear Information System (INIS)

    Tada, Hiroomi; Lashgari, M.; Amini, S.; Khalili, K.; Rappaport, J.; Wong-Staal, F.

    1990-01-01

    Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease of the central nervous system caused by the JC virus (JCV), a human papovavirus. PML is a relatively rare disease seen predominantly in immunocompromised individuals and is a frequent complication observed in AIDS patients. The significantly higher incidence of PML in AIDS patients than in other immunosuppressive disorders has suggested that the presence of human immunodeficiency virus type 1 (HIV-1) in the brain may directly or indirectly contribute to the pathogenesis of this disease. In the present study the authors have examined the expression of the JCV genome in both glial and non-glial cells in the presence of HIV-1 regulatory proteins. They find that the HIV-1-encoded trans-regulatory protein tat increases the basal activity of the JCV late promoter, JCV L , in glial cells. They conclude that the presence of the HIV-1-encoded tat protein may positively affect the JCV lytic cycle in glial cells by stimulating JCV gene expression. The results suggest a mechanism for the relatively high incidence of PML in AIDS patients than in other immunosuppressive disorders. Furthermore, the findings indicate that the HIV-1 regulatory protein tat may stimulate other viral and perhaps cellular promoters, in addition to its own

  7. Therapeutic immunization with HIV-1 Tat reduces immune activation and loss of regulatory T-cells and improves immune function in subjects on HAART.

    Directory of Open Access Journals (Sweden)

    Barbara Ensoli

    2010-11-01

    Full Text Available Although HAART suppresses HIV replication, it is often unable to restore immune homeostasis. Consequently, non-AIDS-defining diseases are increasingly seen in treated individuals. This is attributed to persistent virus expression in reservoirs and to cell activation. Of note, in CD4(+ T cells and monocyte-macrophages of virologically-suppressed individuals, there is continued expression of multi-spliced transcripts encoding HIV regulatory proteins. Among them, Tat is essential for virus gene expression and replication, either in primary infection or for virus reactivation during HAART, when Tat is expressed, released extracellularly and exerts, on both the virus and the immune system, effects that contribute to disease maintenance. Here we report results of an ad hoc exploratory interim analysis (up to 48 weeks on 87 virologically-suppressed HAART-treated individuals enrolled in a phase II randomized open-label multicentric clinical trial of therapeutic immunization with Tat (ISS T-002. Eighty-eight virologically-suppressed HAART-treated individuals, enrolled in a parallel prospective observational study at the same sites (ISS OBS T-002, served for intergroup comparison. Immunization with Tat was safe, induced durable immune responses, and modified the pattern of CD4(+ and CD8(+ cellular activation (CD38 and HLA-DR together with reduction of biochemical activation markers and persistent increases of regulatory T cells. This was accompanied by a progressive increment of CD4(+ T cells and B cells with reduction of CD8(+ T cells and NK cells, which were independent from the type of antiretroviral regimen. Increase in central and effector memory and reduction in terminally-differentiated effector memory CD4(+ and CD8(+ T cells were accompanied by increases of CD4(+ and CD8(+ T cell responses against Env and recall antigens. Of note, more immune-compromised individuals experienced greater therapeutic effects. In contrast, these changes were opposite

  8. Modulation of microtubule assembly by the HIV-1 Tat protein is strongly dependent on zinc binding to Tat

    Directory of Open Access Journals (Sweden)

    Muller Sylviane

    2008-07-01

    Full Text Available Abstract Background During HIV-1 infection, the Tat protein plays a key role by transactivating the transcription of the HIV-1 proviral DNA. In addition, Tat induces apoptosis of non-infected T lymphocytes, leading to a massive loss of immune competence. This apoptosis is notably mediated by the interaction of Tat with microtubules, which are dynamic components essential for cell structure and division. Tat binds two Zn2+ ions through its conserved cysteine-rich region in vitro, but the role of zinc in the structure and properties of Tat is still controversial. Results To investigate the role of zinc, we first characterized Tat apo- and holo-forms by fluorescence correlation spectroscopy and time-resolved fluorescence spectroscopy. Both of the Tat forms are monomeric and poorly folded but differ by local conformational changes in the vicinity of the cysteine-rich region. The interaction of the two Tat forms with tubulin dimers and microtubules was monitored by analytical ultracentrifugation, turbidity measurements and electron microscopy. At 20°C, both of the Tat forms bind tubulin dimers, but only the holo-Tat was found to form discrete complexes. At 37°C, both forms promoted the nucleation and increased the elongation rates of tubulin assembly. However, only the holo-Tat increased the amount of microtubules, decreased the tubulin critical concentration, and stabilized the microtubules. In contrast, apo-Tat induced a large amount of tubulin aggregates. Conclusion Our data suggest that holo-Tat corresponds to the active form, responsible for the Tat-mediated apoptosis.

  9. Neuroprotective effect of TAT-14-3-3ε fusion protein against cerebral ischemia/reperfusion injury in rats.

    Directory of Open Access Journals (Sweden)

    Yuanjun Zhu

    Full Text Available Stroke is the major cause of death and disability worldwide, and the thrombolytic therapy currently available was unsatisfactory. 14-3-3ε is a well characterized member of 14-3-3 family, and has been reported to protect neurons against apoptosis in cerebral ischemia. However, it cannot transverse blood brain barrier (BBB due to its large size. A protein transduction domain (PTD of HIV TAT protein, is capable of delivering a large variety of proteins into the brain. In this study, we generated a fusion protein TAT-14-3-3ε, and evaluated its potential neuroprotective effect in rat focal ischemia/reperfusion (I/R model. Western blot analysis validated the efficient transduction of TAT-14-3-3ε fusion protein into brain via a route of intravenous injection. TAT-14-3-3ε pre-treatment 2 h before ischemia significantly reduced cerebral infarction volume and improved neurologic score, while post-treatment 2 h after ischemia was less effective. Importantly, pre- or post-ischemic treatment with TAT-14-3-3ε significantly increased the number of surviving neurons as determined by Nissl staining, and attenuated I/R-induced neuronal apoptosis as showed by the decrease in apoptotic cell numbers and the inhibition of caspase-3 activity. Moreover, the introduction of 14-3-3ε into brain by TAT-mediated delivering reduced the formation of autophagosome, attenuated LC3B-II upregulation and reversed p62 downregulation induced by ischemic injury. Such inhibition of autophagy was reversed by treatment with an autophagy inducer rapamycin (RAP, which also attenuated the neuroprotective effect of TAT-14-3-3ε. Conversely, autophagy inhibitor 3-methyladenine (3-MA inhibited I/R-induced the increase in autophagic activity, and attenuated I/R-induced brain infarct. These results suggest that TAT-14-3-3ε can be efficiently transduced into brain and exert significantly protective effect against brain ischemic injury through inhibiting neuronal apoptosis and autophagic

  10. Management of synchronized network activity by highly active neurons

    International Nuclear Information System (INIS)

    Shein, Mark; Raichman, Nadav; Ben-Jacob, Eshel; Volman, Vladislav; Hanein, Yael

    2008-01-01

    Increasing evidence supports the idea that spontaneous brain activity may have an important functional role. Cultured neuronal networks provide a suitable model system to search for the mechanisms by which neuronal spontaneous activity is maintained and regulated. This activity is marked by synchronized bursting events (SBEs)—short time windows (hundreds of milliseconds) of rapid neuronal firing separated by long quiescent periods (seconds). However, there exists a special subset of rapidly firing neurons whose activity also persists between SBEs. It has been proposed that these highly active (HA) neurons play an important role in the management (i.e. establishment, maintenance and regulation) of the synchronized network activity. Here, we studied the dynamical properties and the functional role of HA neurons in homogeneous and engineered networks, during early network development, upon recovery from chemical inhibition and in response to electrical stimulations. We found that their sequences of inter-spike intervals (ISI) exhibit long time correlations and a unimodal distribution. During the network's development and under intense inhibition, the observed activity follows a transition period during which mostly HA neurons are active. Studying networks with engineered geometry, we found that HA neurons are precursors (the first to fire) of the spontaneous SBEs and are more responsive to electrical stimulations

  11. Managing Brain Extracellular K(+) during Neuronal Activity

    DEFF Research Database (Denmark)

    Larsen, Brian Roland; Stoica, Anca; MacAulay, Nanna

    2016-01-01

    characteristics required to fulfill their distinct physiological roles in clearance of K(+) from the extracellular space in the face of neuronal activity. Understanding the nature, impact and effects of the various Na(+)/K(+)-ATPase isoform combinations in K(+) management in the central nervous system might...... understanding of the pathological events occurring during disease....

  12. Modulation of neuronal network activity with ghrelin

    NARCIS (Netherlands)

    Stoyanova, Irina; Rutten, Wim; le Feber, Jakob

    2012-01-01

    Ghrelin is a neuropeptide regulating multiple physiological processes, including high brain functions such as learning and memory formation. However, the effect of ghrelin on network activity patterns and developments has not been studied yet. Therefore, we used dissociated cortical neurons plated

  13. Hindbrain Catecholamine Neurons Activate Orexin Neurons During Systemic Glucoprivation in Male Rats.

    Science.gov (United States)

    Li, Ai-Jun; Wang, Qing; Elsarelli, Megan M; Brown, R Lane; Ritter, Sue

    2015-08-01

    Hindbrain catecholamine neurons are required for elicitation of feeding responses to glucose deficit, but the forebrain circuitry required for these responses is incompletely understood. Here we examined interactions of catecholamine and orexin neurons in eliciting glucoprivic feeding. Orexin neurons, located in the perifornical lateral hypothalamus (PeFLH), are heavily innervated by hindbrain catecholamine neurons, stimulate food intake, and increase arousal and behavioral activation. Orexin neurons may therefore contribute importantly to appetitive responses, such as food seeking, during glucoprivation. Retrograde tracing results showed that nearly all innervation of the PeFLH from the hindbrain originated from catecholamine neurons and some raphe nuclei. Results also suggested that many catecholamine neurons project collaterally to the PeFLH and paraventricular hypothalamic nucleus. Systemic administration of the antiglycolytic agent, 2-deoxy-D-glucose, increased food intake and c-Fos expression in orexin neurons. Both responses were eliminated by a lesion of catecholamine neurons innervating orexin neurons using the retrogradely transported immunotoxin, anti-dopamine-β-hydroxylase saporin, which is specifically internalized by dopamine-β-hydroxylase-expressing catecholamine neurons. Using designer receptors exclusively activated by designer drugs in transgenic rats expressing Cre recombinase under the control of tyrosine hydroxylase promoter, catecholamine neurons in cell groups A1 and C1 of the ventrolateral medulla were activated selectively by peripheral injection of clozapine-N-oxide. Clozapine-N-oxide injection increased food intake and c-Fos expression in PeFLH orexin neurons as well as in paraventricular hypothalamic nucleus neurons. In summary, catecholamine neurons are required for the activation of orexin neurons during glucoprivation. Activation of orexin neurons may contribute to appetitive responses required for glucoprivic feeding.

  14. A New Population of Parvocellular Oxytocin Neurons Controlling Magnocellular Neuron Activity and Inflammatory Pain Processing.

    Science.gov (United States)

    Eliava, Marina; Melchior, Meggane; Knobloch-Bollmann, H Sophie; Wahis, Jérôme; da Silva Gouveia, Miriam; Tang, Yan; Ciobanu, Alexandru Cristian; Triana Del Rio, Rodrigo; Roth, Lena C; Althammer, Ferdinand; Chavant, Virginie; Goumon, Yannick; Gruber, Tim; Petit-Demoulière, Nathalie; Busnelli, Marta; Chini, Bice; Tan, Linette L; Mitre, Mariela; Froemke, Robert C; Chao, Moses V; Giese, Günter; Sprengel, Rolf; Kuner, Rohini; Poisbeau, Pierrick; Seeburg, Peter H; Stoop, Ron; Charlet, Alexandre; Grinevich, Valery

    2016-03-16

    Oxytocin (OT) is a neuropeptide elaborated by the hypothalamic paraventricular (PVN) and supraoptic (SON) nuclei. Magnocellular OT neurons of these nuclei innervate numerous forebrain regions and release OT into the blood from the posterior pituitary. The PVN also harbors parvocellular OT cells that project to the brainstem and spinal cord, but their function has not been directly assessed. Here, we identified a subset of approximately 30 parvocellular OT neurons, with collateral projections onto magnocellular OT neurons and neurons of deep layers of the spinal cord. Evoked OT release from these OT neurons suppresses nociception and promotes analgesia in an animal model of inflammatory pain. Our findings identify a new population of OT neurons that modulates nociception in a two tier process: (1) directly by release of OT from axons onto sensory spinal cord neurons and inhibiting their activity and (2) indirectly by stimulating OT release from SON neurons into the periphery. Copyright © 2016 Elsevier Inc. All rights reserved.

  15. Role of neuronal activity in regulating the structure and function of auditory neurons

    International Nuclear Information System (INIS)

    Born, D.E.

    1986-01-01

    The role of afferent activity in maintaining neuronal structure and function was investigated in second order auditory neurons in nucleus magnocellularis (NM) of the chicken. The cochlea provides the major excitatory input to NM neurons via the eighth nerve. Removal of the cochlea causes dramatic changes in NM neurons. To determine if the elimination of neuronal activity is responsible for the changes in NM seen after cochlea removal, tetrodotoxin was used block action potentials in the cochlear ganglion cells. Tetrodotoxin injections into the perilymph reliably blocked neuronal activity in the cochlear nerve and NM. Far field recordings of sound-evoked potentials revealed that responses returned within 6 hours. Changes in amino acid incorporation in NM neurons were measured by giving intracardiac injections of 3 H-leucine and preparing tissue for autoradiographic demonstration of incorporated amino acid. Grain counts over individual neurons revealed that a single injection of tetrodotoxin produced a 40% decrease in grain density in ipsilateral NM neurons. It is concluded that neuronal activity plays an important contribution to the maintenance of the normal properties of NM neurons

  16. Neuronal medium that supports basic synaptic functions and activity of human neurons in vitro.

    Science.gov (United States)

    Bardy, Cedric; van den Hurk, Mark; Eames, Tameji; Marchand, Cynthia; Hernandez, Ruben V; Kellogg, Mariko; Gorris, Mark; Galet, Ben; Palomares, Vanessa; Brown, Joshua; Bang, Anne G; Mertens, Jerome; Böhnke, Lena; Boyer, Leah; Simon, Suzanne; Gage, Fred H

    2015-05-19

    Human cell reprogramming technologies offer access to live human neurons from patients and provide a new alternative for modeling neurological disorders in vitro. Neural electrical activity is the essence of nervous system function in vivo. Therefore, we examined neuronal activity in media widely used to culture neurons. We found that classic basal media, as well as serum, impair action potential generation and synaptic communication. To overcome this problem, we designed a new neuronal medium (BrainPhys basal + serum-free supplements) in which we adjusted the concentrations of inorganic salts, neuroactive amino acids, and energetic substrates. We then tested that this medium adequately supports neuronal activity and survival of human neurons in culture. Long-term exposure to this physiological medium also improved the proportion of neurons that were synaptically active. The medium was designed to culture human neurons but also proved adequate for rodent neurons. The improvement in BrainPhys basal medium to support neurophysiological activity is an important step toward reducing the gap between brain physiological conditions in vivo and neuronal models in vitro.

  17. Neurochemistry of neurons in the ventrolateral medulla activated by hypotension: Are the same neurons activated by glucoprivation?

    Science.gov (United States)

    Parker, Lindsay M; Le, Sheng; Wearne, Travis A; Hardwick, Kate; Kumar, Natasha N; Robinson, Katherine J; McMullan, Simon; Goodchild, Ann K

    2017-06-15

    Previous studies have demonstrated that a range of stimuli activate neurons, including catecholaminergic neurons, in the ventrolateral medulla. Not all catecholaminergic neurons are activated and other neurochemical content is largely unknown hence whether stimulus specific populations exist is unclear. Here we determine the neurochemistry (using in situ hybridization) of catecholaminergic and noncatecholaminergic neurons which express c-Fos immunoreactivity throughout the rostrocaudal extent of the ventrolateral medulla, in Sprague Dawley rats treated with hydralazine or saline. Distinct neuronal populations containing PPCART, PPPACAP, and PPNPY mRNAs, which were largely catecholaminergic, were activated by hydralazine but not saline. Both catecholaminergic and noncatecholaminergic neurons containing preprotachykinin and prepro-enkephalin (PPE) mRNAs were also activated, with the noncatecholaminergic population located in the rostral C1 region. Few GlyT2 neurons were activated. A subset of these data was then used to compare the neuronal populations activated by 2-deoxyglucose evoked glucoprivation (Brain Structure and Function (2015) 220:117). Hydralazine activated more neurons than 2-deoxyglucose but similar numbers of catecholaminergic neurons. Commonly activated populations expressing PPNPY and PPE mRNAs were defined. These likely include PPNPY expressing catecholaminergic neurons projecting to vasopressinergic and corticotrophin releasing factor neurons in the paraventricular nucleus, which when activated result in elevated plasma vasopressin and corticosterone. Stimulus specific neurons included noncatecholaminergic neurons and a few PPE positive catecholaminergic neuron but neurochemical codes were largely unidentified. Reasons for the lack of identification of stimulus specific neurons, readily detectable using electrophysiology in anaesthetized preparations and for which neural circuits can be defined, are discussed. © 2017 Wiley Periodicals, Inc.

  18. A Tat-grafted anti-nucleic acid antibody acquires nuclear-localization property and a preference for TAR RNA

    International Nuclear Information System (INIS)

    Jeong, Jong-Geun; Kim, Dong-Sik; Kim, Yong-Sung; Kwon, Myung-Hee

    2011-01-01

    Highlights: → We generate ' H3 Tat-3D8' by grafting Tat 48-60 peptide to VH CDR of 3D8 scFv antibody. → H3 Tat-3D8 antibody retains nucleic acid binding and hydrolyzing activities. → H3 Tat-3D8 acquires a preference for TAR RNA structure. → Properties of Tat 48-60 is transferred to an antibody via Tat-grafting into a CDR. -- Abstract: The 3D8 single chain variable fragment (3D8 scFv) is an anti-nucleic acid antibody that can hydrolyze nucleic acids and enter the cytosol of cells without reaching the nucleus. The Tat peptide, derived from the basic region of the HIV-1 Tat protein, translocates to cell nuclei and has TAR RNA binding activity. In this study, we generated a Tat-grafted antibody ( H3 Tat-3D8) by replacing complementarity-determining region 3 (CDR3) within the VH domain of the 3D8 scFv with a Tat 48-60 peptide (GRKKRRQRRRPPQ). H3 Tat-3D8 retained the DNA-binding and DNA-hydrolyzing activity of the scFv, and translocated to the nuclei of HeLa cells and preferentially recognized TAR RNA. Thus, the properties associated with the Tat peptide were transferred to the antibody via Tat-grafting without loss of the intrinsic DNA-binding and hydrolyzing activities of the 3D8 scFv antibody.

  19. Models of the stochastic activity of neurones

    CERN Document Server

    Holden, Arun Vivian

    1976-01-01

    These notes have grown from a series of seminars given at Leeds between 1972 and 1975. They represent an attempt to gather together the different kinds of model which have been proposed to account for the stochastic activity of neurones, and to provide an introduction to this area of mathematical biology. A striking feature of the electrical activity of the nervous system is that it appears stochastic: this is apparent at all levels of recording, ranging from intracellular recordings to the electroencephalogram. The chapters start with fluctuations in membrane potential, proceed through single unit and synaptic activity and end with the behaviour of large aggregates of neurones: L have chgaen this seque~~e\\/~~';uggest that the interesting behaviourr~f :the nervous system - its individuality, variability and dynamic forms - may in part result from the stochastic behaviour of its components. I would like to thank Dr. Julio Rubio for reading and commenting on the drafts, Mrs. Doris Beighton for producing the fin...

  20. Essential roles of mitochondrial depolarization in neuron loss through microglial activation and attraction toward neurons.

    Science.gov (United States)

    Nam, Min-Kyung; Shin, Hyun-Ah; Han, Ji-Hye; Park, Dae-Wook; Rhim, Hyangshuk

    2013-04-10

    As life spans increased, neurodegenerative disorders that affect aging populations have also increased. Progressive neuronal loss in specific brain regions is the most common cause of neurodegenerative disease; however, key determinants mediating neuron loss are not fully understood. Using a model of mitochondrial membrane potential (ΔΨm) loss, we found only 25% cell loss in SH-SY5Y (SH) neuronal mono-cultures, but interestingly, 85% neuronal loss occurred when neurons were co-cultured with BV2 microglia. SH neurons overexpressing uncoupling protein 2 exhibited an increase in neuron-microglia interactions, which represent an early step in microglial phagocytosis of neurons. This result indicates that ΔΨm loss in SH neurons is an important contributor to recruitment of BV2 microglia. Notably, we show that ΔΨm loss in BV2 microglia plays a crucial role in microglial activation and phagocytosis of damaged SH neurons. Thus, our study demonstrates that ΔΨm loss in both neurons and microglia is a critical determinant of neuron loss. These findings also offer new insights into neuroimmunological and bioenergetical aspects of neurodegenerative disease. Copyright © 2013 Elsevier B.V. All rights reserved.

  1. Intrinsically active and pacemaker neurons in pluripotent stem cell-derived neuronal populations.

    Science.gov (United States)

    Illes, Sebastian; Jakab, Martin; Beyer, Felix; Gelfert, Renate; Couillard-Despres, Sébastien; Schnitzler, Alfons; Ritter, Markus; Aigner, Ludwig

    2014-03-11

    Neurons generated from pluripotent stem cells (PSCs) self-organize into functional neuronal assemblies in vitro, generating synchronous network activities. Intriguingly, PSC-derived neuronal assemblies develop spontaneous activities that are independent of external stimulation, suggesting the presence of thus far undetected intrinsically active neurons (IANs). Here, by using mouse embryonic stem cells, we provide evidence for the existence of IANs in PSC-neuronal networks based on extracellular multielectrode array and intracellular patch-clamp recordings. IANs remain active after pharmacological inhibition of fast synaptic communication and possess intrinsic mechanisms required for autonomous neuronal activity. PSC-derived IANs are functionally integrated in PSC-neuronal populations, contribute to synchronous network bursting, and exhibit pacemaker properties. The intrinsic activity and pacemaker properties of the neuronal subpopulation identified herein may be particularly relevant for interventions involving transplantation of neural tissues. IANs may be a key element in the regulation of the functional activity of grafted as well as preexisting host neuronal networks.

  2. Epac activation sensitizes rat sensory neurons via activation of Ras

    Science.gov (United States)

    Shariati, Behzad; Thompson, Eric L.; Nicol, Grant D.; Vasko, Michael R.

    2015-01-01

    Guanine nucleotide exchange factors directly activated by cAMP (Epacs) have emerged as important signaling molecules mediating persistent hypersensitivity in animal models of inflammation, by augmenting the excitability of sensory neurons. Although Epacs activate numerous downstream signaling cascades, the intracellular signaling which mediates Epac-induced sensitization of capsaicin-sensitive sensory neurons remains unknown. Here, we demonstrate that selective activation of Epacs with 8-CPT-2′-O-Me-cAMP-AM (8CPT-AM) increases the number of action potentials (APs) generated by a ramp of depolarizing current and augments the evoked release of calcitonin gene-related peptide (CGRP) from isolated rat sensory neurons. Internal perfusion of capsaicin-sensitive sensory neurons with GDP-βS, substituted for GTP, blocks the ability of 8CPT-AM to increase AP firing, demonstrating that Epac-induced sensitization is G-protein dependent. Treatment with 8CPT-AM activates the small G-proteins Rap1 and Ras in cultures of sensory neurons. Inhibition of Rap1, by internal perfusion of a Rap1-neutralizing antibody or through a reduction in the expression of the protein using shRNA does not alter the Epac-induced enhancement of AP generation or CGRP release, despite the fact that in most other cell types, Epacs act as Rap-GEFs. In contrast, inhibition of Ras through expression of a dominant negative Ras (DN-Ras) or through internal perfusion of a Ras-neutralizing antibody blocks the increase in AP firing and attenuates the increase in the evoked release of CGRP induced by Epac activation. Thus, in this subpopulation of nociceptive sensory neurons, it is the novel interplay between Epacs and Ras, rather than the canonical Epacs and Rap1 pathway, that is critical for mediating Epac-induced sensitization. PMID:26596174

  3. Epac activation sensitizes rat sensory neurons through activation of Ras.

    Science.gov (United States)

    Shariati, Behzad; Thompson, Eric L; Nicol, Grant D; Vasko, Michael R

    2016-01-01

    Guanine nucleotide exchange factors directly activated by cAMP (Epacs) have emerged as important signaling molecules mediating persistent hypersensitivity in animal models of inflammation, by augmenting the excitability of sensory neurons. Although Epacs activate numerous downstream signaling cascades, the intracellular signaling which mediates Epac-induced sensitization of capsaicin-sensitive sensory neurons remains unknown. Here, we demonstrate that selective activation of Epacs with 8-CPT-2'-O-Me-cAMP-AM (8CPT-AM) increases the number of action potentials (APs) generated by a ramp of depolarizing current and augments the evoked release of calcitonin gene-related peptide (CGRP) from isolated rat sensory neurons. Internal perfusion of capsaicin-sensitive sensory neurons with GDP-βS, substituted for GTP, blocks the ability of 8CPT-AM to increase AP firing, demonstrating that Epac-induced sensitization is G-protein dependent. Treatment with 8CPT-AM activates the small G-proteins Rap1 and Ras in cultures of sensory neurons. Inhibition of Rap1, by internal perfusion of a Rap1-neutralizing antibody or through a reduction in the expression of the protein using shRNA does not alter the Epac-induced enhancement of AP generation or CGRP release, despite the fact that in most other cell types, Epacs act as Rap-GEFs. In contrast, inhibition of Ras through expression of a dominant negative Ras (DN-Ras) or through internal perfusion of a Ras-neutralizing antibody blocks the increase in AP firing and attenuates the increase in the evoked release of CGRP induced by Epac activation. Thus, in this subpopulation of nociceptive sensory neurons, it is the novel interplay between Epacs and Ras, rather than the canonical Epacs and Rap1 pathway, that is critical for mediating Epac-induced sensitization. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. Population activity structure of excitatory and inhibitory neurons.

    Directory of Open Access Journals (Sweden)

    Sean R Bittner

    Full Text Available Many studies use population analysis approaches, such as dimensionality reduction, to characterize the activity of large groups of neurons. To date, these methods have treated each neuron equally, without taking into account whether neurons are excitatory or inhibitory. We studied population activity structure as a function of neuron type by applying factor analysis to spontaneous activity from spiking networks with balanced excitation and inhibition. Throughout the study, we characterized population activity structure by measuring its dimensionality and the percentage of overall activity variance that is shared among neurons. First, by sampling only excitatory or only inhibitory neurons, we found that the activity structures of these two populations in balanced networks are measurably different. We also found that the population activity structure is dependent on the ratio of excitatory to inhibitory neurons sampled. Finally we classified neurons from extracellular recordings in the primary visual cortex of anesthetized macaques as putative excitatory or inhibitory using waveform classification, and found similarities with the neuron type-specific population activity structure of a balanced network with excitatory clustering. These results imply that knowledge of neuron type is important, and allows for stronger statistical tests, when interpreting population activity structure.

  5. Population activity structure of excitatory and inhibitory neurons.

    Science.gov (United States)

    Bittner, Sean R; Williamson, Ryan C; Snyder, Adam C; Litwin-Kumar, Ashok; Doiron, Brent; Chase, Steven M; Smith, Matthew A; Yu, Byron M

    2017-01-01

    Many studies use population analysis approaches, such as dimensionality reduction, to characterize the activity of large groups of neurons. To date, these methods have treated each neuron equally, without taking into account whether neurons are excitatory or inhibitory. We studied population activity structure as a function of neuron type by applying factor analysis to spontaneous activity from spiking networks with balanced excitation and inhibition. Throughout the study, we characterized population activity structure by measuring its dimensionality and the percentage of overall activity variance that is shared among neurons. First, by sampling only excitatory or only inhibitory neurons, we found that the activity structures of these two populations in balanced networks are measurably different. We also found that the population activity structure is dependent on the ratio of excitatory to inhibitory neurons sampled. Finally we classified neurons from extracellular recordings in the primary visual cortex of anesthetized macaques as putative excitatory or inhibitory using waveform classification, and found similarities with the neuron type-specific population activity structure of a balanced network with excitatory clustering. These results imply that knowledge of neuron type is important, and allows for stronger statistical tests, when interpreting population activity structure.

  6. Population activity structure of excitatory and inhibitory neurons

    Science.gov (United States)

    Doiron, Brent

    2017-01-01

    Many studies use population analysis approaches, such as dimensionality reduction, to characterize the activity of large groups of neurons. To date, these methods have treated each neuron equally, without taking into account whether neurons are excitatory or inhibitory. We studied population activity structure as a function of neuron type by applying factor analysis to spontaneous activity from spiking networks with balanced excitation and inhibition. Throughout the study, we characterized population activity structure by measuring its dimensionality and the percentage of overall activity variance that is shared among neurons. First, by sampling only excitatory or only inhibitory neurons, we found that the activity structures of these two populations in balanced networks are measurably different. We also found that the population activity structure is dependent on the ratio of excitatory to inhibitory neurons sampled. Finally we classified neurons from extracellular recordings in the primary visual cortex of anesthetized macaques as putative excitatory or inhibitory using waveform classification, and found similarities with the neuron type-specific population activity structure of a balanced network with excitatory clustering. These results imply that knowledge of neuron type is important, and allows for stronger statistical tests, when interpreting population activity structure. PMID:28817581

  7. Intratelencephalic corticostriatal neurons equally excite striatonigral and striatopallidal neurons and their discharge activity is selectively reduced in experimental parkinsonism

    OpenAIRE

    Ballion, B. (B.); Mallet, N. (Nicolas); Bezard, E. (E.); Lanciego, J.L. (José Luis); Gonon, F. (Francois)

    2008-01-01

    Striatonigral and striatopallidal neurons form distinct populations of striatal projection neurons. Their discharge activity is imbalanced after dopaminergic degeneration in Parkinson's disease. Striatal projection neurons receive massive cortical excitatory inputs from bilateral intratelencephalic (IT) neurons projecting to both the ipsilateral and contralateral striatum and from collateral axons of ipsilateral neurons that send their main axon through the pyramidal tract (PT). Previous anat...

  8. Neuronal medium that supports basic synaptic functions and activity of human neurons in vitro

    NARCIS (Netherlands)

    Bardy, C.; Hurk, M. van den; Eames, T.; Marchand, C.; Hernandez, R.V.; Kellogg, M.; Gorris, M.A.J.; Galet, B.; Palomares, V.; Brown, J.; Bang, A.G.; Mertens, J.; Bohnke, L.; Boyer, L.; Simon, S.; Gage, F.H.

    2015-01-01

    Human cell reprogramming technologies offer access to live human neurons from patients and provide a new alternative for modeling neurological disorders in vitro. Neural electrical activity is the essence of nervous system function in vivo. Therefore, we examined neuronal activity in media widely

  9. In vitro nuclear interactome of the HIV-1 Tat protein.

    LENUS (Irish Health Repository)

    Gautier, Virginie W

    2009-01-01

    BACKGROUND: One facet of the complexity underlying the biology of HIV-1 resides not only in its limited number of viral proteins, but in the extensive repertoire of cellular proteins they interact with and their higher-order assembly. HIV-1 encodes the regulatory protein Tat (86-101aa), which is essential for HIV-1 replication and primarily orchestrates HIV-1 provirus transcriptional regulation. Previous studies have demonstrated that Tat function is highly dependent on specific interactions with a range of cellular proteins. However they can only partially account for the intricate molecular mechanisms underlying the dynamics of proviral gene expression. To obtain a comprehensive nuclear interaction map of Tat in T-cells, we have designed a proteomic strategy based on affinity chromatography coupled with mass spectrometry. RESULTS: Our approach resulted in the identification of a total of 183 candidates as Tat nuclear partners, 90% of which have not been previously characterised. Subsequently we applied in silico analysis, to validate and characterise our dataset which revealed that the Tat nuclear interactome exhibits unique signature(s). First, motif composition analysis highlighted that our dataset is enriched for domains mediating protein, RNA and DNA interactions, and helicase and ATPase activities. Secondly, functional classification and network reconstruction clearly depicted Tat as a polyvalent protein adaptor and positioned Tat at the nexus of a densely interconnected interaction network involved in a range of biological processes which included gene expression regulation, RNA biogenesis, chromatin structure, chromosome organisation, DNA replication and nuclear architecture. CONCLUSION: We have completed the in vitro Tat nuclear interactome and have highlighted its modular network properties and particularly those involved in the coordination of gene expression by Tat. Ultimately, the highly specialised set of molecular interactions identified will

  10. CRISPR Epigenome Editing of AKAP150 in DRG Neurons Abolishes Degenerative IVD-Induced Neuronal Activation.

    Science.gov (United States)

    Stover, Joshua D; Farhang, Niloofar; Berrett, Kristofer C; Gertz, Jason; Lawrence, Brandon; Bowles, Robby D

    2017-09-06

    Back pain is a major contributor to disability and has significant socioeconomic impacts worldwide. The degenerative intervertebral disc (IVD) has been hypothesized to contribute to back pain, but a better understanding of the interactions between the degenerative IVD and nociceptive neurons innervating the disc and treatment strategies that directly target these interactions is needed to improve our understanding and treatment of back pain. We investigated degenerative IVD-induced changes to dorsal root ganglion (DRG) neuron activity and utilized CRISPR epigenome editing as a neuromodulation strategy. By exposing DRG neurons to degenerative IVD-conditioned media under both normal and pathological IVD pH levels, we demonstrate that degenerative IVDs trigger interleukin (IL)-6-induced increases in neuron activity to thermal stimuli, which is directly mediated by AKAP and enhanced by acidic pH. Utilizing this novel information on AKAP-mediated increases in nociceptive neuron activity, we developed lentiviral CRISPR epigenome editing vectors that modulate endogenous expression of AKAP150 by targeted promoter histone methylation. When delivered to DRG neurons, these epigenome-modifying vectors abolished degenerative IVD-induced DRG-elevated neuron activity while preserving non-pathologic neuron activity. This work elucidates the potential for CRISPR epigenome editing as a targeted gene-based pain neuromodulation strategy. Copyright © 2017 The American Society of Gene and Cell Therapy. Published by Elsevier Inc. All rights reserved.

  11. PDGF-mediated protection of SH-SY5Y cells against Tat toxin involves regulation of extracellular glutamate and intracellular calcium

    International Nuclear Information System (INIS)

    Zhu Xuhui; Yao Honghong; Peng Fuwang; Callen, Shannon; Buch, Shilpa

    2009-01-01

    The human immunodeficiency virus (HIV-1) protein Tat has been implicated in mediating neuronal apoptosis, one of the hallmark features of HIV-associated dementia (HAD). Mitigation of the toxic effects of Tat could thus be a potential mechanism for reducing HIV toxicity in the brain. In this study we demonstrated that Tat-induced neurotoxicity was abolished by NMDA antagonist-MK801, suggesting the role of glutamate in this process. Furthermore, we also found that pretreatment of SH-SY5Y cells with PDGF exerted protection against Tat toxicity by decreasing extracellular glutamate levels. We also demonstrated that extracellular calcium chelator EGTA was able to abolish PDGF-mediated neuroprotection, thereby underscoring the role of calcium signaling in PDGF-mediated neuroprotection. We also showed that Erk signaling pathway was critical for PDGF-mediated protection of cells. Additionally, blocking calcium entry with EGTA resulted in suppression of PDGF-induced Erk activation. These findings thus underscore the role of PDGF-mediated calcium signaling and Erk phosphorylation in the protection of cells against HIV Tat toxicity.

  12. Reliable activation of immature neurons in the adult hippocampus.

    Directory of Open Access Journals (Sweden)

    Lucas A Mongiat

    Full Text Available Neurons born in the adult dentate gyrus develop, mature, and connect over a long interval that can last from six to eight weeks. It has been proposed that, during this period, developing neurons play a relevant role in hippocampal signal processing owing to their distinctive electrical properties. However, it has remained unknown whether immature neurons can be recruited into a network before synaptic and functional maturity have been achieved. To address this question, we used retroviral expression of green fluorescent protein to identify developing granule cells of the adult mouse hippocampus and investigate the balance of afferent excitation, intrinsic excitability, and firing behavior by patch clamp recordings in acute slices. We found that glutamatergic inputs onto young neurons are significantly weaker than those of mature cells, yet stimulation of cortical excitatory axons elicits a similar spiking probability in neurons at either developmental stage. Young neurons are highly efficient in transducing ionic currents into membrane depolarization due to their high input resistance, which decreases substantially in mature neurons as the inward rectifier potassium (Kir conductance increases. Pharmacological blockade of Kir channels in mature neurons mimics the high excitability characteristic of young neurons. Conversely, Kir overexpression induces mature-like firing properties in young neurons. Therefore, the differences in excitatory drive of young and mature neurons are compensated by changes in membrane excitability that render an equalized firing activity. These observations demonstrate that the adult hippocampus continuously generates a population of highly excitable young neurons capable of information processing.

  13. Shaping of neuronal activity through a Brain Computer Interface

    OpenAIRE

    Valero-Aguayo, Luis; Silva-Sauer, Leandro; Velasco-Alvarez, Ricardo; Ron-Angevin, Ricardo

    2014-01-01

    Neuronal responses are human actions which can be measured by an EEG, and which imply changes in waves when neurons are synchronized. This activity could be changed by principles of behaviour analysis. This research tests the efficacy of the behaviour shaping procedure to progressively change neuronal activity, so that those brain responses are adapted according to the differential reinforcement of visual feedback. The Brain Computer Interface (BCI) enables us to record the EEG in real ti...

  14. Recurrently connected and localized neuronal communities initiate coordinated spontaneous activity in neuronal networks

    Science.gov (United States)

    Amin, Hayder; Maccione, Alessandro; Nieus, Thierry

    2017-01-01

    Developing neuronal systems intrinsically generate coordinated spontaneous activity that propagates by involving a large number of synchronously firing neurons. In vivo, waves of spikes transiently characterize the activity of developing brain circuits and are fundamental for activity-dependent circuit formation. In vitro, coordinated spontaneous spiking activity, or network bursts (NBs), interleaved within periods of asynchronous spikes emerge during the development of 2D and 3D neuronal cultures. Several studies have investigated this type of activity and its dynamics, but how a neuronal system generates these coordinated events remains unclear. Here, we investigate at a cellular level the generation of network bursts in spontaneously active neuronal cultures by exploiting high-resolution multielectrode array recordings and computational network modelling. Our analysis reveals that NBs are generated in specialized regions of the network (functional neuronal communities) that feature neuronal links with high cross-correlation peak values, sub-millisecond lags and that share very similar structural connectivity motifs providing recurrent interactions. We show that the particular properties of these local structures enable locally amplifying spontaneous asynchronous spikes and that this mechanism can lead to the initiation of NBs. Through the analysis of simulated and experimental data, we also show that AMPA currents drive the coordinated activity, while NMDA and GABA currents are only involved in shaping the dynamics of NBs. Overall, our results suggest that the presence of functional neuronal communities with recurrent local connections allows a neuronal system to generate spontaneous coordinated spiking activity events. As suggested by the rules used for implementing our computational model, such functional communities might naturally emerge during network development by following simple constraints on distance-based connectivity. PMID:28749937

  15. Recurrently connected and localized neuronal communities initiate coordinated spontaneous activity in neuronal networks.

    Directory of Open Access Journals (Sweden)

    Davide Lonardoni

    2017-07-01

    Full Text Available Developing neuronal systems intrinsically generate coordinated spontaneous activity that propagates by involving a large number of synchronously firing neurons. In vivo, waves of spikes transiently characterize the activity of developing brain circuits and are fundamental for activity-dependent circuit formation. In vitro, coordinated spontaneous spiking activity, or network bursts (NBs, interleaved within periods of asynchronous spikes emerge during the development of 2D and 3D neuronal cultures. Several studies have investigated this type of activity and its dynamics, but how a neuronal system generates these coordinated events remains unclear. Here, we investigate at a cellular level the generation of network bursts in spontaneously active neuronal cultures by exploiting high-resolution multielectrode array recordings and computational network modelling. Our analysis reveals that NBs are generated in specialized regions of the network (functional neuronal communities that feature neuronal links with high cross-correlation peak values, sub-millisecond lags and that share very similar structural connectivity motifs providing recurrent interactions. We show that the particular properties of these local structures enable locally amplifying spontaneous asynchronous spikes and that this mechanism can lead to the initiation of NBs. Through the analysis of simulated and experimental data, we also show that AMPA currents drive the coordinated activity, while NMDA and GABA currents are only involved in shaping the dynamics of NBs. Overall, our results suggest that the presence of functional neuronal communities with recurrent local connections allows a neuronal system to generate spontaneous coordinated spiking activity events. As suggested by the rules used for implementing our computational model, such functional communities might naturally emerge during network development by following simple constraints on distance-based connectivity.

  16. Nicotinic activation of laterodorsal tegmental neurons

    DEFF Research Database (Denmark)

    Ishibashi, Masaru; Leonard, Christopher S; Kohlmeier, Kristi A

    2009-01-01

    Identifying the neurological mechanisms underlying nicotine reinforcement is a healthcare imperative, if society is to effectively combat tobacco addiction. The majority of studies of the neurobiology of addiction have focused on dopamine (DA)-containing neurons of the ventral tegmental area (VTA......). However, recent data suggest that neurons of the laterodorsal tegmental (LDT) nucleus, which sends cholinergic, GABAergic, and glutamatergic-containing projections to DA-containing neurons of the VTA, are critical to gating normal functioning of this nucleus. The actions of nicotine on LDT neurons...... are unknown. We addressed this issue by examining the effects of nicotine on identified cholinergic and non-cholinergic LDT neurons using whole-cell patch clamp and Ca(2+)-imaging methods in brain slices from mice (P12-P45). Nicotine applied by puffer pipette or bath superfusion elicited membrane...

  17. MD simulation of the Tat/Cyclin T1/CDK9 complex revealing the hidden catalytic cavity within the CDK9 molecule upon Tat binding.

    Directory of Open Access Journals (Sweden)

    Kaori Asamitsu

    Full Text Available In this study, we applied molecular dynamics (MD simulation to analyze the dynamic behavior of the Tat/CycT1/CDK9 tri-molecular complex and revealed the structural changes of P-TEFb upon Tat binding. We found that Tat could deliberately change the local flexibility of CycT1. Although the structural coordinates of the H1 and H2 helices did not substantially change, H1', H2', and H3' exhibited significant changes en masse. Consequently, the CycT1 residues involved in Tat binding, namely Tat-recognition residues (TRRs, lost their flexibility with the addition of Tat to P-TEFb. In addition, we clarified the structural variation of CDK9 in complex with CycT1 in the presence or absence of Tat. Interestingly, Tat addition significantly reduced the structural variability of the T-loop, thus consolidating the structural integrity of P-TEFb. Finally, we deciphered the formation of the hidden catalytic cavity of CDK9 upon Tat binding. MD simulation revealed that the PITALRE signature sequence of CDK9 flips the inactive kinase cavity of CDK9 into the active form by connecting with Thr186, which is crucial for its activity, thus presumably recruiting the substrate peptide such as the C-terminal domain of RNA pol II. These findings provide vital information for the development of effective novel anti-HIV drugs with CDK9 catalytic activity as the target.

  18. Measure of synchrony in the activity of intrinsic cardiac neurons

    International Nuclear Information System (INIS)

    Longpré, Jean-Philippe; Salavatian, Siamak; Jacquemet, Vincent; Beaumont, Eric; Armour, J Andrew; Ardell, Jeffrey L

    2014-01-01

    Recent multielectrode array recordings in ganglionated plexi of canine atria have opened the way to the study of population dynamics of intrinsic cardiac neurons. These data provide critical insights into the role of local processing that these ganglia play in the regulation of cardiac function. Low firing rates, marked non-stationarity, interplay with the cardiovascular and pulmonary systems and artifacts generated by myocardial activity create new constraints not present in brain recordings for which almost all neuronal analysis techniques have been developed. We adapted and extended the jitter-based synchrony index (SI) to (1) provide a robust and computationally efficient tool for assessing the level and statistical significance of SI between cardiac neurons, (2) estimate the bias on SI resulting from neuronal activity possibly hidden in myocardial artifacts, (3) quantify the synchrony or anti-synchrony between neuronal activity and the phase in the cardiac and respiratory cycles. The method was validated on firing time series from a total of 98 individual neurons identified in 8 dog experiments. SI ranged from −0.14 to 0.66, with 23 pairs of neurons with SI > 0.1. The estimated bias due to artifacts was typically <1%. Strongly cardiovascular- and pulmonary-related neurons (SI > 0.5) were found. Results support the use of jitter-based SI in the context of intrinsic cardiac neurons. (paper)

  19. Spiking Activity of a LIF Neuron in Distributed Delay Framework

    Directory of Open Access Journals (Sweden)

    Saket Kumar Choudhary

    2016-06-01

    Full Text Available Evolution of membrane potential and spiking activity for a single leaky integrate-and-fire (LIF neuron in distributed delay framework (DDF is investigated. DDF provides a mechanism to incorporate memory element in terms of delay (kernel function into a single neuron models. This investigation includes LIF neuron model with two different kinds of delay kernel functions, namely, gamma distributed delay kernel function and hypo-exponential distributed delay kernel function. Evolution of membrane potential for considered models is studied in terms of stationary state probability distribution (SPD. Stationary state probability distribution of membrane potential (SPDV for considered neuron models are found asymptotically similar which is Gaussian distributed. In order to investigate the effect of membrane potential delay, rate code scheme for neuronal information processing is applied. Firing rate and Fano-factor for considered neuron models are calculated and standard LIF model is used for comparative study. It is noticed that distributed delay increases the spiking activity of a neuron. Increase in spiking activity of neuron in DDF is larger for hypo-exponential distributed delay function than gamma distributed delay function. Moreover, in case of hypo-exponential delay function, a LIF neuron generates spikes with Fano-factor less than 1.

  20. Sleep-Active Neurons: Conserved Motors of Sleep

    Science.gov (United States)

    Bringmann, Henrik

    2018-01-01

    Sleep is crucial for survival and well-being. This behavioral and physiological state has been studied in all major genetically accessible model animals, including rodents, fish, flies, and worms. Genetic and optogenetic studies have identified several neurons that control sleep, making it now possible to compare circuit mechanisms across species. The “motor” of sleep across animal species is formed by neurons that depolarize at the onset of sleep to actively induce this state by directly inhibiting wakefulness. These sleep-inducing neurons are themselves controlled by inhibitory or activating upstream pathways, which act as the “drivers” of the sleep motor: arousal inhibits “sleep-active” neurons whereas various sleep-promoting “tiredness” pathways converge onto sleep-active neurons to depolarize them. This review provides the first overview of sleep-active neurons across the major model animals. The occurrence of sleep-active neurons and their regulation by upstream pathways in both vertebrate and invertebrate species suggests that these neurons are general and ancient components that evolved early in the history of nervous systems. PMID:29618588

  1. Cellular Links between Neuronal Activity and Energy Homeostasis

    OpenAIRE

    Shetty, Pavan K.; Galeffi, Francesca; Turner, Dennis A.

    2012-01-01

    Neuronal activity, astrocytic responses to this activity, and energy homeostasis are linked together during baseline, conscious conditions, and short-term rapid activation (as occurs with sensory or motor function). Nervous system energy homeostasis also varies during long-term physiological conditions (i.e., development and aging) and with adaptation to pathological conditions, such as ischemia or low glucose. Neuronal activation requires increased metabolism (i.e., ATP generation) which lea...

  2. Critical role of NADPH oxidase in neuronal oxidative damage and microglia activation following traumatic brain injury.

    Directory of Open Access Journals (Sweden)

    Quan-Guang Zhang

    Full Text Available BACKGROUND: Oxidative stress is known to play an important role in the pathology of traumatic brain injury. Mitochondria are thought to be the major source of the damaging reactive oxygen species (ROS following TBI. However, recent work has revealed that the membrane, via the enzyme NADPH oxidase can also generate the superoxide radical (O(2(-, and thereby potentially contribute to the oxidative stress following TBI. The current study thus addressed the potential role of NADPH oxidase in TBI. METHODOLOGY/PRINCIPAL FINDINGS: The results revealed that NADPH oxidase activity in the cerebral cortex and hippocampal CA1 region increases rapidly following controlled cortical impact in male mice, with an early peak at 1 h, followed by a secondary peak from 24-96 h after TBI. In situ localization using oxidized hydroethidine and the neuronal marker, NeuN, revealed that the O(2(- induction occurred in neurons at 1 h after TBI. Pre- or post-treatment with the NADPH oxidase inhibitor, apocynin markedly inhibited microglial activation and oxidative stress damage. Apocynin also attenuated TBI-induction of the Alzheimer's disease proteins β-amyloid and amyloid precursor protein. Finally, both pre- and post-treatment of apocynin was also shown to induce significant neuroprotection against TBI. In addition, a NOX2-specific inhibitor, gp91ds-tat was also shown to exert neuroprotection against TBI. CONCLUSIONS/SIGNIFICANCE: As a whole, the study demonstrates that NADPH oxidase activity and superoxide production exhibit a biphasic elevation in the hippocampus and cortex following TBI, which contributes significantly to the pathology of TBI via mediation of oxidative stress damage, microglial activation, and AD protein induction in the brain following TBI.

  3. A triad of lys12, lys41, arg78 spatial domain, a novel identified heparin binding site on tat protein, facilitates tat-driven cell adhesion.

    Directory of Open Access Journals (Sweden)

    Jing Ai

    Full Text Available Tat protein, released by HIV-infected cells, has a battery of important biological effects leading to distinct AIDS-associated pathologies. Cell surface heparan sulfate protoglycans (HSPGs have been accepted as endogenous Tat receptors, and the Tat basic domain has been identified as the heparin binding site. However, findings that deletion or substitution of the basic domain inhibits but does not completely eliminate Tat-heparin interactions suggest that the basic domain is not the sole Tat heparin binding site. In the current study, an approach integrating computational modeling, mutagenesis, biophysical and cell-based assays was used to elucidate a novel, high affinity heparin-binding site: a Lys12, Lys41, Arg78 (KKR spatial domain. This domain was also found to facilitate Tat-driven β1 integrin activation, producing subsequent SLK cell adhesion in an HSPG-dependent manner, but was not involved in Tat internalization. The identification of this new heparin binding site may foster further insight into the nature of Tat-heparin interactions and subsequent biological functions, facilitating the rational design of new therapeutics against Tat-mediated pathological events.

  4. Beyond Neuronal Activity Markers: Select Immediate Early Genes in Striatal Neuron Subtypes Functionally Mediate Psychostimulant Addiction

    Directory of Open Access Journals (Sweden)

    Ramesh Chandra

    2017-06-01

    Full Text Available Immediate early genes (IEGs were traditionally used as markers of neuronal activity in striatum in response to stimuli including drugs of abuse such as psychostimulants. Early studies using these neuronal activity markers led to important insights in striatal neuron subtype responsiveness to psychostimulants. Such studies have helped identify striatum as a critical brain center for motivational, reinforcement and habitual behaviors in psychostimulant addiction. While the use of IEGs as neuronal activity markers in response to psychostimulants and other stimuli persists today, the functional role and implications of these IEGs has often been neglected. Nonetheless, there is a subset of research that investigates the functional role of IEGs in molecular, cellular and behavioral alterations by psychostimulants through striatal medium spiny neuron (MSN subtypes, the two projection neuron subtypes in striatum. This review article will address and highlight the studies that provide a functional mechanism by which IEGs mediate psychostimulant molecular, cellular and behavioral plasticity through MSN subtypes. Insight into the functional role of IEGs in striatal MSN subtypes could provide improved understanding into addiction and neuropsychiatric diseases affecting striatum, such as affective disorders and compulsive disorders characterized by dysfunctional motivation and habitual behavior.

  5. Neuron matters: electric activation of neuronal tissue is dependent on the interaction between the neuron and the electric field.

    Science.gov (United States)

    Ye, Hui; Steiger, Amanda

    2015-08-12

    In laboratory research and clinical practice, externally-applied electric fields have been widely used to control neuronal activity. It is generally accepted that neuronal excitability is controlled by electric current that depolarizes or hyperpolarizes the excitable cell membrane. What determines the amount of polarization? Research on the mechanisms of electric stimulation focus on the optimal control of the field properties (frequency, amplitude, and direction of the electric currents) to improve stimulation outcomes. Emerging evidence from modeling and experimental studies support the existence of interactions between the targeted neurons and the externally-applied electric fields. With cell-field interaction, we suggest a two-way process. When a neuron is positioned inside an electric field, the electric field will induce a change in the resting membrane potential by superimposing an electrically-induced transmembrane potential (ITP). At the same time, the electric field can be perturbed and re-distributed by the cell. This cell-field interaction may play a significant role in the overall effects of stimulation. The redistributed field can cause secondary effects to neighboring cells by altering their geometrical pattern and amount of membrane polarization. Neurons excited by the externally-applied electric field can also affect neighboring cells by ephaptic interaction. Both aspects of the cell-field interaction depend on the biophysical properties of the neuronal tissue, including geometric (i.e., size, shape, orientation to the field) and electric (i.e., conductivity and dielectricity) attributes of the cells. The biophysical basis of the cell-field interaction can be explained by the electromagnetism theory. Further experimental and simulation studies on electric stimulation of neuronal tissue should consider the prospect of a cell-field interaction, and a better understanding of tissue inhomogeneity and anisotropy is needed to fully appreciate the neural

  6. GABAergic inhibition through synergistic astrocytic neuronal interaction transiently decreases vasopressin neuronal activity during hypoosmotic challenge.

    Science.gov (United States)

    Wang, Yu-Feng; Sun, Min-Yu; Hou, Qiuling; Hamilton, Kathryn A

    2013-04-01

    The neuropeptide vasopressin is crucial to mammalian osmotic regulation. Local hypoosmotic challenge transiently decreases and then increases vasopressin secretion. To investigate mechanisms underlying this transient response, we examined the effects of hypoosmotic challenge on the electrical activity of rat hypothalamic supraoptic nucleus (SON) vasopressin neurons using patch-clamp recordings. We found that 5 min exposure of hypothalamic slices to hypoosmotic solution transiently increased inhibitory postsynaptic current (IPSC) frequency and reduced the firing rate of vasopressin neurons. Recovery occurred by 10 min of exposure, even though the osmolality remained low. The γ-aminobutyric acid (GABA)A receptor blocker, gabazine, blocked the IPSCs and the hypoosmotic suppression of firing. The gliotoxin l-aminoadipic acid blocked the increase in IPSC frequency at 5 min and the recovery of firing at 10 min, indicating astrocytic involvement in hypoosmotic modulation of vasopressin neuronal activity. Moreover, β-alanine, an osmolyte of astrocytes and GABA transporter (GAT) inhibitor, blocked the increase in IPSC frequency at 5 min of hypoosmotic challenge. Confocal microscopy of immunostained SON sections revealed that astrocytes and magnocellular neurons both showed positive staining of vesicular GATs (VGAT). Hypoosmotic stimulation in vivo reduced the number of VGAT-expressing neurons, and increased co-localisation and molecular association of VGAT with glial fibrillary acidic protein that increased significantly by 10 min. By 30 min, neuronal VGAT labelling was partially restored, and astrocytic VGAT was relocated to the ventral portion while it decreased in the somatic zone of the SON. Thus, synergistic astrocytic and neuronal GABAergic inhibition could ensure that vasopressin neuron firing is only transiently suppressed under hypoosmotic conditions. © 2013 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

  7. Dopamine suppresses neuronal activity of Helisoma B5 neurons via a D2-like receptor, activating PLC and K channels.

    Science.gov (United States)

    Zhong, L R; Artinian, L; Rehder, V

    2013-01-03

    Dopamine (DA) plays fundamental roles as a neurotransmitter and neuromodulator in the central nervous system. How DA modulates the electrical excitability of individual neurons to elicit various behaviors is of great interest in many systems. The buccal ganglion of the freshwater pond snail Helisoma trivolvis contains the neuronal circuitry for feeding and DA is known to modulate the feeding motor program in Helisoma. The buccal neuron B5 participates in the control of gut contractile activity and is surrounded by dopaminergic processes, which are expected to release DA. In order to study whether DA modulates the electrical activity of individual B5 neurons, we performed experiments on physically isolated B5 neurons in culture and on B5 neurons within the buccal ganglion in situ. We report that DA application elicited a strong hyperpolarization in both conditions and turned the electrical activity from a spontaneously firing state to an electrically silent state. Using the cell culture system, we demonstrated that the strong hyperpolarization was inhibited by the D2 receptor antagonist sulpiride and the phospholipase C (PLC) inhibitor U73122, indicating that DA affected the membrane potential of B5 neurons through the activation of a D2-like receptor and PLC. Further studies revealed that the DA-induced hyperpolarization was inhibited by the K channel blockers 4-aminopyridine and tetraethylammonium, suggesting that K channels might serve as the ultimate target of DA signaling. Through its modulatory effect on the electrical activity of B5 neurons, the release of DA in vivo may contribute to a neuronal output that results in a variable feeding motor program. Copyright © 2012 IBRO. Published by Elsevier Ltd. All rights reserved.

  8. Toxoplasma gondii Actively Inhibits Neuronal Function in Chronically Infected Mice

    Science.gov (United States)

    Haroon, Fahad; Händel, Ulrike; Angenstein, Frank; Goldschmidt, Jürgen; Kreutzmann, Peter; Lison, Holger; Fischer, Klaus-Dieter; Scheich, Henning; Wetzel, Wolfram; Schlüter, Dirk; Budinger, Eike

    2012-01-01

    Upon infection with the obligate intracellular parasite Toxoplasma gondii, fast replicating tachyzoites infect a broad spectrum of host cells including neurons. Under the pressure of the immune response, tachyzoites convert into slow-replicating bradyzoites, which persist as cysts in neurons. Currently, it is unclear whether T. gondii alters the functional activity of neurons, which may contribute to altered behaviour of T. gondii–infected mice and men. In the present study we demonstrate that upon oral infection with T. gondii cysts, chronically infected BALB/c mice lost over time their natural fear against cat urine which was paralleled by the persistence of the parasite in brain regions affecting behaviour and odor perception. Detailed immunohistochemistry showed that in infected neurons not only parasitic cysts but also the host cell cytoplasm and some axons stained positive for Toxoplasma antigen suggesting that parasitic proteins might directly interfere with neuronal function. In fact, in vitro live cell calcium (Ca2+) imaging studies revealed that tachyzoites actively manipulated Ca2+ signalling upon glutamate stimulation leading either to hyper- or hypo-responsive neurons. Experiments with the endoplasmatic reticulum Ca2+ uptake inhibitor thapsigargin indicate that tachyzoites deplete Ca2+ stores in the endoplasmatic reticulum. Furthermore in vivo studies revealed that the activity-dependent uptake of the potassium analogue thallium was reduced in cyst harbouring neurons indicating their functional impairment. The percentage of non-functional neurons increased over time In conclusion, both bradyzoites and tachyzoites functionally silence infected neurons, which may significantly contribute to the altered behaviour of the host. PMID:22530040

  9. Toxoplasma gondii actively inhibits neuronal function in chronically infected mice.

    Directory of Open Access Journals (Sweden)

    Fahad Haroon

    Full Text Available Upon infection with the obligate intracellular parasite Toxoplasma gondii, fast replicating tachyzoites infect a broad spectrum of host cells including neurons. Under the pressure of the immune response, tachyzoites convert into slow-replicating bradyzoites, which persist as cysts in neurons. Currently, it is unclear whether T. gondii alters the functional activity of neurons, which may contribute to altered behaviour of T. gondii-infected mice and men. In the present study we demonstrate that upon oral infection with T. gondii cysts, chronically infected BALB/c mice lost over time their natural fear against cat urine which was paralleled by the persistence of the parasite in brain regions affecting behaviour and odor perception. Detailed immunohistochemistry showed that in infected neurons not only parasitic cysts but also the host cell cytoplasm and some axons stained positive for Toxoplasma antigen suggesting that parasitic proteins might directly interfere with neuronal function. In fact, in vitro live cell calcium (Ca(2+ imaging studies revealed that tachyzoites actively manipulated Ca(2+ signalling upon glutamate stimulation leading either to hyper- or hypo-responsive neurons. Experiments with the endoplasmatic reticulum Ca(2+ uptake inhibitor thapsigargin indicate that tachyzoites deplete Ca(2+ stores in the endoplasmatic reticulum. Furthermore in vivo studies revealed that the activity-dependent uptake of the potassium analogue thallium was reduced in cyst harbouring neurons indicating their functional impairment. The percentage of non-functional neurons increased over time In conclusion, both bradyzoites and tachyzoites functionally silence infected neurons, which may significantly contribute to the altered behaviour of the host.

  10. Basal Forebrain Gating by Somatostatin Neurons Drives Prefrontal Cortical Activity.

    Science.gov (United States)

    Espinosa, Nelson; Alonso, Alejandra; Morales, Cristian; Espinosa, Pedro; Chávez, Andrés E; Fuentealba, Pablo

    2017-11-17

    The basal forebrain provides modulatory input to the cortex regulating brain states and cognitive processing. Somatostatin-expressing neurons constitute a heterogeneous GABAergic population known to functionally inhibit basal forebrain cortically projecting cells thus favoring sleep and cortical synchronization. However, it remains unclear if somatostatin cells can regulate population activity patterns in the basal forebrain and modulate cortical dynamics. Here, we demonstrate that somatostatin neurons regulate the corticopetal synaptic output of the basal forebrain impinging on cortical activity and behavior. Optogenetic inactivation of somatostatin neurons in vivo rapidly modified neural activity in the basal forebrain, with the consequent enhancement and desynchronization of activity in the prefrontal cortex, reflected in both neuronal spiking and network oscillations. Cortical activation was partially dependent on cholinergic transmission, suppressing slow waves and potentiating gamma oscillations. In addition, recruitment dynamics was cell type-specific, with interneurons showing similar temporal profiles, but stronger responses than pyramidal cells. Finally, optogenetic stimulation of quiescent animals during resting periods prompted locomotor activity, suggesting generalized cortical activation and increased arousal. Altogether, we provide physiological and behavioral evidence indicating that somatostatin neurons are pivotal in gating the synaptic output of the basal forebrain, thus indirectly controlling cortical operations via both cholinergic and non-cholinergic mechanisms. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  11. Human neuromelanin: an endogenous microglial activator for dopaminergic neuron death

    OpenAIRE

    Zhang, Wei; Zecca, Luigi; Wilson, Belinda; Ren, RW; Wang, Yong-jun; Wang, Xiao-min; Hong, Jau-Shyong

    2013-01-01

    Substantial evidence indicates that neuroinflammation caused by over-activation of microglial in the substantia nigra is critical in the pathogenesis of dopaminergic neurodegeneration in Parkinson’s disease (PD). Increasing data demonstrates that environmental factors such as rotenone, paraquat play pivotal roles in the death of dopaminergic neurons. Here, potential role and mechanism of neuromelanin (NM), a major endogenous component in dopaminergic neurons of the substantia nigra, on microg...

  12. Mechanisms for multiple activity modes of VTA dopamine neurons

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    Andrew eOster

    2015-07-01

    Full Text Available Midbrain ventral segmental area (VTA dopaminergic neurons send numerous projections to cortical and sub-cortical areas, and diffusely release dopamine (DA to their targets. DA neurons display a range of activity modes that vary in frequency and degree of burst firing. Importantly, DA neuronal bursting is associated with a significantly greater degree of DA release than an equivalent tonic activity pattern. Here, we introduce a single compartmental, conductance-based computational model for DA cell activity that captures the behavior of DA neuronal dynamics and examine the multiple factors that underlie DA firing modes: the strength of the SK conductance, the amount of drive, and GABA inhibition. Our results suggest that neurons with low SK conductance fire in a fast firing mode, are correlated with burst firing, and require higher levels of applied current before undergoing depolarization block. We go on to consider the role of GABAergic inhibition on an ensemble of dynamical classes of DA neurons and find that strong GABA inhibition suppresses burst firing. Our studies suggest differences in the distribution of the SK conductance and GABA inhibition levels may indicate subclasses of DA neurons within the VTA. We further identify, that by considering alternate potassium dynamics, the dynamics display burst patterns that terminate via depolarization block, akin to those observed in vivo in VTA DA neurons and in substantia nigra pars compacta DA cell preparations under apamin application. In addition, we consider the generation of transient burst firing events that are NMDA-initiated or elicited by a sudden decrease of GABA inhibition, that is, disinhibition.

  13. Neuronal Activation After Prolonged Immobilization: Do the Same or Different Neurons Respond to a Novel Stressor?

    Science.gov (United States)

    Marín-Blasco, Ignacio; Muñoz-Abellán, Cristina; Andero, Raül; Nadal, Roser; Armario, Antonio

    2018-04-01

    Despite extensive research on the impact of emotional stressors on brain function using immediate-early genes (e.g., c-fos), there are still important questions that remain unanswered such as the reason for the progressive decline of c-fos expression in response to prolonged stress and the neuronal populations activated by different stressors. This study tackles these 2 questions by evaluating c-fos expression in response to 2 different emotional stressors applied sequentially, and performing a fluorescent double labeling of c-Fos protein and c-fos mRNA on stress-related brain areas. Results were complemented with the assessment of the hypothalamic-pituitary-adrenal axis activation. We showed that the progressive decline of c-fos expression could be related to 2 differing mechanisms involving either transcriptional repression or changes in stimulatory inputs. Moreover, the neuronal populations that respond to the different stressors appear to be predominantly separated in high-level processing areas (e.g., medial prefrontal cortex). However, in low-hierarchy areas (e.g., paraventricular nucleus of the hypothalamus) neuronal populations appear to respond unspecifically. The data suggest that the distinct physiological and behavioral consequences of emotional stressors, and their implication in the development of psychopathologies, are likely to be closely associated with neuronal populations specifically activated by each stressor.

  14. Relaxed evolution in the tyrosine aminotransferase gene tat in old world fruit bats (Chiroptera: Pteropodidae).

    Science.gov (United States)

    Shen, Bin; Fang, Tao; Yang, Tianxiao; Jones, Gareth; Irwin, David M; Zhang, Shuyi

    2014-01-01

    Frugivorous and nectarivorous bats fuel their metabolism mostly by using carbohydrates and allocate the restricted amounts of ingested proteins mainly for anabolic protein syntheses rather than for catabolic energy production. Thus, it is possible that genes involved in protein (amino acid) catabolism may have undergone relaxed evolution in these fruit- and nectar-eating bats. The tyrosine aminotransferase (TAT, encoded by the Tat gene) is the rate-limiting enzyme in the tyrosine catabolic pathway. To test whether the Tat gene has undergone relaxed evolution in the fruit- and nectar-eating bats, we obtained the Tat coding region from 20 bat species including four Old World fruit bats (Pteropodidae) and two New World fruit bats (Phyllostomidae). Phylogenetic reconstructions revealed a gene tree in which all echolocating bats (including the New World fruit bats) formed a monophyletic group. The phylogenetic conflict appears to stem from accelerated TAT protein sequence evolution in the Old World fruit bats. Our molecular evolutionary analyses confirmed a change in the selection pressure acting on Tat, which was likely caused by a relaxation of the evolutionary constraints on the Tat gene in the Old World fruit bats. Hepatic TAT activity assays showed that TAT activities in species of the Old World fruit bats are significantly lower than those of insectivorous bats and omnivorous mice, which was not caused by a change in TAT protein levels in the liver. Our study provides unambiguous evidence that the Tat gene has undergone relaxed evolution in the Old World fruit bats in response to changes in their metabolism due to the evolution of their special diet.

  15. Relaxed evolution in the tyrosine aminotransferase gene tat in old world fruit bats (Chiroptera: Pteropodidae.

    Directory of Open Access Journals (Sweden)

    Bin Shen

    Full Text Available Frugivorous and nectarivorous bats fuel their metabolism mostly by using carbohydrates and allocate the restricted amounts of ingested proteins mainly for anabolic protein syntheses rather than for catabolic energy production. Thus, it is possible that genes involved in protein (amino acid catabolism may have undergone relaxed evolution in these fruit- and nectar-eating bats. The tyrosine aminotransferase (TAT, encoded by the Tat gene is the rate-limiting enzyme in the tyrosine catabolic pathway. To test whether the Tat gene has undergone relaxed evolution in the fruit- and nectar-eating bats, we obtained the Tat coding region from 20 bat species including four Old World fruit bats (Pteropodidae and two New World fruit bats (Phyllostomidae. Phylogenetic reconstructions revealed a gene tree in which all echolocating bats (including the New World fruit bats formed a monophyletic group. The phylogenetic conflict appears to stem from accelerated TAT protein sequence evolution in the Old World fruit bats. Our molecular evolutionary analyses confirmed a change in the selection pressure acting on Tat, which was likely caused by a relaxation of the evolutionary constraints on the Tat gene in the Old World fruit bats. Hepatic TAT activity assays showed that TAT activities in species of the Old World fruit bats are significantly lower than those of insectivorous bats and omnivorous mice, which was not caused by a change in TAT protein levels in the liver. Our study provides unambiguous evidence that the Tat gene has undergone relaxed evolution in the Old World fruit bats in response to changes in their metabolism due to the evolution of their special diet.

  16. PERSPECTIVE: Electrical activity enhances neuronal survival and regeneration

    Science.gov (United States)

    Corredor, Raul G.; Goldberg, Jeffrey L.

    2009-10-01

    The failure of regeneration in the central nervous system (CNS) remains an enormous scientific and clinical challenge. After injury or in degenerative diseases, neurons in the adult mammalian CNS fail to regrow their axons and reconnect with their normal targets, and furthermore the neurons frequently die and are not normally replaced. While significant progress has been made in understanding the molecular basis for this lack of regenerative ability, a second approach has gained momentum: replacing lost neurons or lost connections with artificial electrical circuits that interface with the nervous system. In the visual system, gene therapy-based 'optogenetics' prostheses represent a competing technology. Now, the two approaches are converging, as recent data suggest that electrical activity itself, via the molecular signaling pathways such activity stimulates, is sufficient to induce neuronal survival and regeneration, particularly in retinal ganglion cells. Here, we review these data, discuss the effects of electrical activity on neurons' molecular signaling pathways and propose specific mechanisms by which exogenous electrical activity may be acting to enhance survival and regeneration.

  17. Vasoactive intestinal peptide and electrical activity influence neuronal survival

    International Nuclear Information System (INIS)

    Brenneman, D.E.; Eiden, L.E.

    1986-01-01

    Blockage of electrical activity in dissociated spinal cord cultures results in a significant loss of neurons during a critical period in development. Decreases in neuronal cell numbers and 125 I-labeled tetanus toxin fixation produced by electrical blockage with tetrodotoxin (TTX) were prevented by addition of vasoactive intestinal peptide (VIP) to the nutrient medium. The most effective concentration of VIP was 0.1 nM. At higher concentrations, the survival-enhancing effect of VIP on TTX-treated cultures was attenuated. Addition of the peptide alone had no significant effect on neuronal cell counts or tetanus toxin fixation. With the same experimental conditions, two closely related peptides, PHI-27 (peptide, histidyl-isoleucine amide) and secretin, were found not to increase the number of neurons in TTX-treated cultures. Interference with VIP action by VIP antiserum resulted in neuronal losses that were not significantly different from those observed after TTX treatment. These data indicate that under conditions of electrical blockade a neurotrophic action of VIP on neuronal survival can be demonstrated

  18. Tat-haFGF14–154 Upregulates ADAM10 to Attenuate the Alzheimer Phenotype of APP/PS1 Mice through the PI3K-CREB-IRE1α/XBP1 Pathway

    Directory of Open Access Journals (Sweden)

    Tian Meng

    2017-06-01

    Full Text Available Acid fibroblast growth factor (aFGF has shown neuroprotection in Alzheimer’s disease (AD models in previous studies, yet its mechanism is still uncertain. Here we report that the efficacy of Tat-haFGF14–154 is markedly increased when loaded cationic liposomes for intranasal delivery are intranasally administered to APP/PS1 mice. Our results demonstrated that liposomal Tat-haFGF14–154 treatment significantly ameliorated behavioral deficits, relieved brain Aβ burden, and increased the expression and activity of disintegrin and metalloproteinase domain-containing protein 10 (ADAM10 in the brain. Tat-haFGF14–154 antagonized Aβ1–42-induced cell death and structural damage in rat primary neurons in an ADAM10-dependent manner, which, in turn, was promoted by the activation of XBP1 splicing and modulated by the PI3K-CREB pathway. Both knockdown of ADAM10 and inhibition of PI3K (LY294002 negated Tat-haFGF14–154 rescue. Thus, Tat-haFGF14–154 activates the IRE1α/XBP1 pathway of the unfolded protein response (UPR against the endoplasmic reticulum (ER stress induced by Aβ, and, subsequently, the nuclear translocation of spliced XBP1 (XBP1s promotes transcription of ADAM10. These results highlight the important role of ADAM10 and its activation through the PI3K-CREB-IRE1α/XBP1 pathway as a key factor in the mechanism of neuroprotection for Tat-haFGF14–154.

  19. Cellular Links between Neuronal Activity and Energy Homeostasis.

    Science.gov (United States)

    Shetty, Pavan K; Galeffi, Francesca; Turner, Dennis A

    2012-01-01

    Neuronal activity, astrocytic responses to this activity, and energy homeostasis are linked together during baseline, conscious conditions, and short-term rapid activation (as occurs with sensory or motor function). Nervous system energy homeostasis also varies during long-term physiological conditions (i.e., development and aging) and with adaptation to pathological conditions, such as ischemia or low glucose. Neuronal activation requires increased metabolism (i.e., ATP generation) which leads initially to substrate depletion, induction of a variety of signals for enhanced astrocytic function, and increased local blood flow and substrate delivery. Energy generation (particularly in mitochondria) and use during ATP hydrolysis also lead to considerable heat generation. The local increases in blood flow noted following neuronal activation can both enhance local substrate delivery but also provides a heat sink to help cool the brain and removal of waste by-products. In this review we highlight the interactions between short-term neuronal activity and energy metabolism with an emphasis on signals and factors regulating astrocyte function and substrate supply.

  20. Cellular Links Between Neuronal Activity and Energy Homeostasis

    Directory of Open Access Journals (Sweden)

    Pavan K Shetty

    2012-03-01

    Full Text Available Neuronal activity, astrocytic responses to this activity, and energy homeostasis are linked together during baseline, conscious conditions, and short-term rapid activation (as occurs with sensory or motor function. Nervous system energy homeostasis also varies during long-term physiological conditions (ie, development and aging and with adaptation to pathological conditions, such as ischemia or low glucose. Neuronal activation requires increased metabolism (i.e., ATP generation which leads initially to substrate depletion, induction of a variety of signals for enhanced astrocytic function, and increased local blood flow and substrate delivery. Energy generation (particularly in mitochondria and use during ATP hydrolysis also lead to considerable heat generation. The local increases in blood flow noted following neuronal activation can both enhance local substrate delivery but also provides a heat sink to help cool the brain and removal of waste byproducts. In this review we highlight the interactions between short-term neuronal activity and energy metabolism with an emphasis on signals and factors regulating astrocyte function and substrate supply.

  1. Activity of Raphé Serotonergic Neurons Controls Emotional Behaviors

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    Anne Teissier

    2015-12-01

    Full Text Available Despite the well-established role of serotonin signaling in mood regulation, causal relationships between serotonergic neuronal activity and behavior remain poorly understood. Using a pharmacogenetic approach, we find that selectively increasing serotonergic neuronal activity in wild-type mice is anxiogenic and reduces floating in the forced-swim test, whereas inhibition has no effect on the same measures. In a developmental mouse model of altered emotional behavior, increased anxiety and depression-like behaviors correlate with reduced dorsal raphé and increased median raphé serotonergic activity. These mice display blunted responses to serotonergic stimulation and behavioral rescues through serotonergic inhibition. Furthermore, we identify opposing consequences of dorsal versus median raphé serotonergic neuron inhibition on floating behavior, together suggesting that median raphé hyperactivity increases anxiety, whereas a low dorsal/median raphé serotonergic activity ratio increases depression-like behavior. Thus, we find a critical role of serotonergic neuronal activity in emotional regulation and uncover opposing roles of median and dorsal raphé function.

  2. Activity of Raphé Serotonergic Neurons Controls Emotional Behaviors.

    Science.gov (United States)

    Teissier, Anne; Chemiakine, Alexei; Inbar, Benjamin; Bagchi, Sneha; Ray, Russell S; Palmiter, Richard D; Dymecki, Susan M; Moore, Holly; Ansorge, Mark S

    2015-12-01

    Despite the well-established role of serotonin signaling in mood regulation, causal relationships between serotonergic neuronal activity and behavior remain poorly understood. Using a pharmacogenetic approach, we find that selectively increasing serotonergic neuronal activity in wild-type mice is anxiogenic and reduces floating in the forced-swim test, whereas inhibition has no effect on the same measures. In a developmental mouse model of altered emotional behavior, increased anxiety and depression-like behaviors correlate with reduced dorsal raphé and increased median raphé serotonergic activity. These mice display blunted responses to serotonergic stimulation and behavioral rescues through serotonergic inhibition. Furthermore, we identify opposing consequences of dorsal versus median raphé serotonergic neuron inhibition on floating behavior, together suggesting that median raphé hyperactivity increases anxiety, whereas a low dorsal/median raphé serotonergic activity ratio increases depression-like behavior. Thus, we find a critical role of serotonergic neuronal activity in emotional regulation and uncover opposing roles of median and dorsal raphé function. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  3. Spontaneous neuronal activity as a self-organized critical phenomenon

    Science.gov (United States)

    de Arcangelis, L.; Herrmann, H. J.

    2013-01-01

    Neuronal avalanches are a novel mode of activity in neuronal networks, experimentally found in vitro and in vivo, and exhibit a robust critical behaviour. Avalanche activity can be modelled within the self-organized criticality framework, including threshold firing, refractory period and activity-dependent synaptic plasticity. The size and duration distributions confirm that the system acts in a critical state, whose scaling behaviour is very robust. Next, we discuss the temporal organization of neuronal avalanches. This is given by the alternation between states of high and low activity, named up and down states, leading to a balance between excitation and inhibition controlled by a single parameter. During these periods both the single neuron state and the network excitability level, keeping memory of past activity, are tuned by homeostatic mechanisms. Finally, we verify if a system with no characteristic response can ever learn in a controlled and reproducible way. Learning in the model occurs via plastic adaptation of synaptic strengths by a non-uniform negative feedback mechanism. Learning is a truly collective process and the learning dynamics exhibits universal features. Even complex rules can be learned provided that the plastic adaptation is sufficiently slow.

  4. Tat-PRAS40 prevent hippocampal HT-22 cell death and oxidative stress induced animal brain ischemic insults.

    Science.gov (United States)

    Shin, Min Jea; Kim, Dae Won; Jo, Hyo Sang; Cho, Su Bin; Park, Jung Hwan; Lee, Chi Hern; Yeo, Eun Ji; Choi, Yeon Joo; Kim, Ji An; Hwang, Jung Soon; Sohn, Eun Jeong; Jeong, Ji-Heon; Kim, Duk-Soo; Kwon, Hyeok Yil; Cho, Yong-Jun; Lee, Keunwook; Han, Kyu Hyung; Park, Jinseu; Eum, Won Sik; Choi, Soo Young

    2016-08-01

    Proline rich Akt substrate (PRAS40) is a component of mammalian target of rapamycin complex 1 (mTORC1) and is known to play an important role against reactive oxygen species-induced cell death. However, the precise function of PRAS40 in ischemia remains unclear. Thus, we investigated whether Tat-PRAS40, a cell-permeable fusion protein, has a protective function against oxidative stress-induced hippocampal neuronal (HT-22) cell death in an animal model of ischemia. We showed that Tat-PRAS40 transduced into HT-22 cells, and significantly protected against cell death by reducing the levels of H2O2 and derived reactive species, and DNA fragmentation as well as via the regulation of Bcl-2, Bax, and caspase 3 expression levels in H2O2 treated cells. Also, we showed that transduced Tat-PARS40 protein markedly increased phosphorylated RRAS40 expression levels and 14-3-3σ complex via the Akt signaling pathway. In an animal ischemia model, Tat-PRAS40 effectively transduced into the hippocampus in animal brain and significantly protected against neuronal cell death in the CA1 region. We showed that Tat-PRAS40 protein effectively transduced into hippocampal neuronal cells and markedly protected against neuronal cell damage. Therefore, we suggest that Tat-PRAS40 protein may be used as a therapeutic protein for ischemia and oxidative stress-induced brain disorders. Copyright © 2016 Elsevier Inc. All rights reserved.

  5. Nucleus Ambiguus Cholinergic Neurons Activated by Acupuncture: Relation to Enkephalin

    Science.gov (United States)

    Guo, Zhi-Ling; Li, Min; Longhurst, John C.

    2012-01-01

    Acupuncture regulates autonomic function. Our previous studies have shown that electroacupuncture (EA) at the Jianshi–Neiguan acupoints (P5–P6, underlying the median nerve) inhibits central sympathetic outflow and attenuates excitatory cardiovascular reflexes, in part, through an opioid mechanism. It is unknown if EA at these acupoints influences the parasympathetic system. Thus, using c-Fos expression, we examined activation of nucleus ambiguus (NAmb) neurons by EA, their relation to cholinergic (preganglionic parasympathetic) neurons and those containing enkephalin. To enhance detection of cell bodies containing enkephalin, colchicine (90–100 μg/kg) was administered into the subarachnoid space of cats 30 hr prior to EA or sham-operated controls for EA. Following bilateral barodenervation and cervical vagotomy, either EA for 30 min at P5–P6 acupoints or control stimulation (needle placement at P5–P6 without stimulation) was applied. While perikarya containing enkephalin were observed in some medullary nuclei (e.g., râphe), only enkephalin-containing neuronal processes were found in the NAmb. Compared to controls (n=4), more c-Fos immunoreactivity, located principally in close proximity to fibers containing enkephalin was noted in the NAmb of EA-treated cats (n=5; P<0.01). Moreover, neurons double-labeled with c-Fos and choline acetyltransferase in the NAmb were identified in EA-treated, but not the control animals. These data demonstrate for the first time that EA activates preganglionic parasympathetic neurons in the NAmb. Because of their close proximity, these EA-activated neurons likely interact with nerve fibers containing enkephalin. These results suggest that EA at the P5–P6 acupoints has the potential to influence parasympathetic outflow and cardiovascular function, likely through an enkephalinergic mechanism. PMID:22306033

  6. Pseudorabies virus infection alters neuronal activity and connectivity in vitro.

    Directory of Open Access Journals (Sweden)

    Kelly M McCarthy

    2009-10-01

    Full Text Available Alpha-herpesviruses, including human herpes simplex virus 1 & 2, varicella zoster virus and the swine pseudorabies virus (PRV, infect the peripheral nervous system of their hosts. Symptoms of infection often include itching, numbness, or pain indicative of altered neurological function. To determine if there is an in vitro electrophysiological correlate to these characteristic in vivo symptoms, we infected cultured rat sympathetic neurons with well-characterized strains of PRV known to produce virulent or attenuated symptoms in animals. Whole-cell patch clamp recordings were made at various times after infection. By 8 hours of infection with virulent PRV, action potential (AP firing rates increased substantially and were accompanied by hyperpolarized resting membrane potentials and spikelet-like events. Coincident with the increase in AP firing rate, adjacent neurons exhibited coupled firing events, first with AP-spikelets and later with near identical resting membrane potentials and AP firing. Small fusion pores between adjacent cell bodies formed early after infection as demonstrated by transfer of the low molecular weight dye, Lucifer Yellow. Later, larger pores formed as demonstrated by transfer of high molecular weight Texas red-dextran conjugates between infected cells. Further evidence for viral-induced fusion pores was obtained by infecting neurons with a viral mutant defective for glycoprotein B, a component of the viral membrane fusion complex. These infected neurons were essentially identical to mock infected neurons: no increased AP firing, no spikelet-like events, and no electrical or dye transfer. Infection with PRV Bartha, an attenuated circuit-tracing strain delayed, but did not eliminate the increased neuronal activity and coupling events. We suggest that formation of fusion pores between infected neurons results in electrical coupling and elevated firing rates, and that these processes may contribute to the altered neural

  7. Intracellular trafficking of superparamagnetic iron oxide nanoparticles conjugated with TAT peptide: 3-dimensional electron tomography analysis

    Energy Technology Data Exchange (ETDEWEB)

    Nair, Baiju G.; Fukuda, Takahiro; Mizuki, Toru; Hanajiri, Tatsuro [Bio-Nano Electronics Research Centre, Toyo University, Saitama 350-8585 (Japan); Maekawa, Toru, E-mail: maekawa@toyo.jp [Bio-Nano Electronics Research Centre, Toyo University, Saitama 350-8585 (Japan)

    2012-05-18

    Highlights: Black-Right-Pointing-Pointer We study the intracellular localisation of TAT-SPIONs using 3-D electron tomography. Black-Right-Pointing-Pointer 3-D images of TAT-SPIONs in a cell are clearly shown. Black-Right-Pointing-Pointer Release of TAT-SPIONs from endocytic vesicles into the cytoplasm is clearly shown. -- Abstract: Internalisation of nanoparticles conjugated with cell penetrating peptides is a promising approach to various drug delivery applications. Cell penetrating peptides such as transactivating transcriptional activator (TAT) peptides derived from HIV-1 proteins are effective intracellular delivery vectors for a wide range of nanoparticles and pharmaceutical agents thanks to their amicable ability to enter cells and minimum cytotoxicity. Although different mechanisms of intracellular uptake and localisation have been proposed for TAT conjugated nanoparticles, it is necessary to visualise the particles on a 3-D plane in order to investigate the actual intracellular uptake and localisation. Here, we study the intracellular localisation and trafficking of TAT peptide conjugated superparamagnetic ion oxide nanoparticles (TAT-SPIONs) using 3-D electron tomography. 3-D tomograms clearly show the location of TAT-SPIONs in a cell and their slow release from the endocytic vesicles into the cytoplasm. The present methodology may well be utilised for further investigations of the behaviours of nanoparticles in cells and eventually for the development of nano drug delivery systems.

  8. Intracellular trafficking of superparamagnetic iron oxide nanoparticles conjugated with TAT peptide: 3-dimensional electron tomography analysis

    International Nuclear Information System (INIS)

    Nair, Baiju G.; Fukuda, Takahiro; Mizuki, Toru; Hanajiri, Tatsuro; Maekawa, Toru

    2012-01-01

    Highlights: ► We study the intracellular localisation of TAT-SPIONs using 3-D electron tomography. ► 3-D images of TAT-SPIONs in a cell are clearly shown. ► Release of TAT-SPIONs from endocytic vesicles into the cytoplasm is clearly shown. -- Abstract: Internalisation of nanoparticles conjugated with cell penetrating peptides is a promising approach to various drug delivery applications. Cell penetrating peptides such as transactivating transcriptional activator (TAT) peptides derived from HIV-1 proteins are effective intracellular delivery vectors for a wide range of nanoparticles and pharmaceutical agents thanks to their amicable ability to enter cells and minimum cytotoxicity. Although different mechanisms of intracellular uptake and localisation have been proposed for TAT conjugated nanoparticles, it is necessary to visualise the particles on a 3-D plane in order to investigate the actual intracellular uptake and localisation. Here, we study the intracellular localisation and trafficking of TAT peptide conjugated superparamagnetic ion oxide nanoparticles (TAT-SPIONs) using 3-D electron tomography. 3-D tomograms clearly show the location of TAT-SPIONs in a cell and their slow release from the endocytic vesicles into the cytoplasm. The present methodology may well be utilised for further investigations of the behaviours of nanoparticles in cells and eventually for the development of nano drug delivery systems.

  9. Nucleolar protein trafficking in response to HIV-1 Tat: rewiring the nucleolus.

    Science.gov (United States)

    Jarboui, Mohamed Ali; Bidoia, Carlo; Woods, Elena; Roe, Barbara; Wynne, Kieran; Elia, Giuliano; Hall, William W; Gautier, Virginie W

    2012-01-01

    The trans-activator Tat protein is a viral regulatory protein essential for HIV-1 replication. Tat trafficks to the nucleoplasm and the nucleolus. The nucleolus, a highly dynamic and structured membrane-less sub-nuclear compartment, is the site of rRNA and ribosome biogenesis and is involved in numerous cellular functions including transcriptional regulation, cell cycle control and viral infection. Importantly, transient nucleolar trafficking of both Tat and HIV-1 viral transcripts are critical in HIV-1 replication, however, the role(s) of the nucleolus in HIV-1 replication remains unclear. To better understand how the interaction of Tat with the nucleolar machinery contributes to HIV-1 pathogenesis, we investigated the quantitative changes in the composition of the nucleolar proteome of Jurkat T-cells stably expressing HIV-1 Tat fused to a TAP tag. Using an organellar proteomic approach based on mass spectrometry, coupled with Stable Isotope Labelling in Cell culture (SILAC), we quantified 520 proteins, including 49 proteins showing significant changes in abundance in Jurkat T-cell nucleolus upon Tat expression. Numerous proteins exhibiting a fold change were well characterised Tat interactors and/or known to be critical for HIV-1 replication. This suggests that the spatial control and subcellular compartimentaliation of these cellular cofactors by Tat provide an additional layer of control for regulating cellular machinery involved in HIV-1 pathogenesis. Pathway analysis and network reconstruction revealed that Tat expression specifically resulted in the nucleolar enrichment of proteins collectively participating in ribosomal biogenesis, protein homeostasis, metabolic pathways including glycolytic, pentose phosphate, nucleotides and amino acids biosynthetic pathways, stress response, T-cell signaling pathways and genome integrity. We present here the first differential profiling of the nucleolar proteome of T-cells expressing HIV-1 Tat. We discuss how these

  10. Morphine Tolerance and Physical Dependence Are Altered in Conditional HIV-1 Tat Transgenic Mice.

    Science.gov (United States)

    Fitting, Sylvia; Stevens, David L; Khan, Fayez A; Scoggins, Krista L; Enga, Rachel M; Beardsley, Patrick M; Knapp, Pamela E; Dewey, William L; Hauser, Kurt F

    2016-01-01

    Despite considerable evidence that chronic opiate use selectively affects the pathophysiologic consequences of human immunodeficiency virus type 1 (HIV-1) infection in the nervous system, few studies have examined whether neuro-acquired immune deficiency syndrome (neuroAIDS) might intrinsically alter the pharmacologic responses to chronic opiate exposure. This is an important matter because HIV-1 and opiate abuse are interrelated epidemics, and HIV-1 patients are often prescribed opiates as a treatment of HIV-1-related neuropathic pain. Tolerance and physical dependence are inevitable consequences of frequent and repeated administration of morphine. In the present study, mice expressing HIV-1 Tat in a doxycycline (DOX)-inducible manner [Tat(+)], their Tat(-) controls, and control C57BL/6 mice were chronically exposed to placebo or 75-mg morphine pellets to explore the effects of Tat induction on morphine tolerance and dependence. Antinociceptive tolerance and locomotor activity tolerance were assessed using tail-flick and locomotor activity assays, respectively, and physical dependence was measured with the platform-jumping assay and recording of other withdrawal signs. We found that Tat(+) mice treated with DOX [Tat(+)/DOX] developed an increased tolerance in the tail-flick assay compared with control Tat(-)/DOX and/or C57/DOX mice. Equivalent tolerance was developed in all mice when assessed by locomotor activity. Further, Tat(+)/DOX mice expressed reduced levels of physical dependence to chronic morphine exposure after a 1-mg/kg naloxone challenge compared with control Tat(-)/DOX and/or C57/DOX mice. Assuming the results seen in Tat transgenic mice can be generalized to neuroAIDS, our findings suggest that HIV-1-infected individuals may display heightened analgesic tolerance to similar doses of opiates compared with uninfected individuals and show fewer symptoms of physical dependence. Copyright © 2015 by The American Society for Pharmacology and Experimental

  11. BAD and KATP channels regulate neuron excitability and epileptiform activity.

    Science.gov (United States)

    Martínez-François, Juan Ramón; Fernández-Agüera, María Carmen; Nathwani, Nidhi; Lahmann, Carolina; Burnham, Veronica L; Danial, Nika N; Yellen, Gary

    2018-01-25

    Brain metabolism can profoundly influence neuronal excitability. Mice with genetic deletion or alteration of Bad ( B CL-2 a gonist of cell d eath) exhibit altered brain-cell fuel metabolism, accompanied by resistance to acutely induced epileptic seizures; this seizure protection is mediated by ATP-sensitive potassium (K ATP ) channels. Here we investigated the effect of BAD manipulation on K ATP channel activity and excitability in acute brain slices. We found that BAD's influence on neuronal K ATP channels was cell-autonomous and directly affected dentate granule neuron (DGN) excitability. To investigate the role of neuronal K ATP channels in the anticonvulsant effects of BAD, we imaged calcium during picrotoxin-induced epileptiform activity in entorhinal-hippocampal slices. BAD knockout reduced epileptiform activity, and this effect was lost upon knockout or pharmacological inhibition of K ATP channels. Targeted BAD knockout in DGNs alone was sufficient for the antiseizure effect in slices, consistent with a 'dentate gate' function that is reinforced by increased K ATP channel activity. © 2018, Martínez-François et al.

  12. Behavioural effects of chemogenetic dopamine neuron activation

    NARCIS (Netherlands)

    Boekhoudt, L

    2016-01-01

    Various psychiatric disorders, including schizophrenia, attention-deficit/hyperactivity disorder (ADHD) and major depressive disorder, have been associated with altered dopamine signalling in the brain. However, it remains unclear which specific changes in dopamine activity are related to specific

  13. Scaling of brain metabolism with a fixed energy budget per neuron: implications for neuronal activity, plasticity and evolution.

    Science.gov (United States)

    Herculano-Houzel, Suzana

    2011-03-01

    It is usually considered that larger brains have larger neurons, which consume more energy individually, and are therefore accompanied by a larger number of glial cells per neuron. These notions, however, have never been tested. Based on glucose and oxygen metabolic rates in awake animals and their recently determined numbers of neurons, here I show that, contrary to the expected, the estimated glucose use per neuron is remarkably constant, varying only by 40% across the six species of rodents and primates (including humans). The estimated average glucose use per neuron does not correlate with neuronal density in any structure. This suggests that the energy budget of the whole brain per neuron is fixed across species and brain sizes, such that total glucose use by the brain as a whole, by the cerebral cortex and also by the cerebellum alone are linear functions of the number of neurons in the structures across the species (although the average glucose consumption per neuron is at least 10× higher in the cerebral cortex than in the cerebellum). These results indicate that the apparently remarkable use in humans of 20% of the whole body energy budget by a brain that represents only 2% of body mass is explained simply by its large number of neurons. Because synaptic activity is considered the major determinant of metabolic cost, a conserved energy budget per neuron has several profound implications for synaptic homeostasis and the regulation of firing rates, synaptic plasticity, brain imaging, pathologies, and for brain scaling in evolution.

  14. Scaling of brain metabolism with a fixed energy budget per neuron: implications for neuronal activity, plasticity and evolution.

    Directory of Open Access Journals (Sweden)

    Suzana Herculano-Houzel

    Full Text Available It is usually considered that larger brains have larger neurons, which consume more energy individually, and are therefore accompanied by a larger number of glial cells per neuron. These notions, however, have never been tested. Based on glucose and oxygen metabolic rates in awake animals and their recently determined numbers of neurons, here I show that, contrary to the expected, the estimated glucose use per neuron is remarkably constant, varying only by 40% across the six species of rodents and primates (including humans. The estimated average glucose use per neuron does not correlate with neuronal density in any structure. This suggests that the energy budget of the whole brain per neuron is fixed across species and brain sizes, such that total glucose use by the brain as a whole, by the cerebral cortex and also by the cerebellum alone are linear functions of the number of neurons in the structures across the species (although the average glucose consumption per neuron is at least 10× higher in the cerebral cortex than in the cerebellum. These results indicate that the apparently remarkable use in humans of 20% of the whole body energy budget by a brain that represents only 2% of body mass is explained simply by its large number of neurons. Because synaptic activity is considered the major determinant of metabolic cost, a conserved energy budget per neuron has several profound implications for synaptic homeostasis and the regulation of firing rates, synaptic plasticity, brain imaging, pathologies, and for brain scaling in evolution.

  15. Scaling of Brain Metabolism with a Fixed Energy Budget per Neuron: Implications for Neuronal Activity, Plasticity and Evolution

    Science.gov (United States)

    Herculano-Houzel, Suzana

    2011-01-01

    It is usually considered that larger brains have larger neurons, which consume more energy individually, and are therefore accompanied by a larger number of glial cells per neuron. These notions, however, have never been tested. Based on glucose and oxygen metabolic rates in awake animals and their recently determined numbers of neurons, here I show that, contrary to the expected, the estimated glucose use per neuron is remarkably constant, varying only by 40% across the six species of rodents and primates (including humans). The estimated average glucose use per neuron does not correlate with neuronal density in any structure. This suggests that the energy budget of the whole brain per neuron is fixed across species and brain sizes, such that total glucose use by the brain as a whole, by the cerebral cortex and also by the cerebellum alone are linear functions of the number of neurons in the structures across the species (although the average glucose consumption per neuron is at least 10× higher in the cerebral cortex than in the cerebellum). These results indicate that the apparently remarkable use in humans of 20% of the whole body energy budget by a brain that represents only 2% of body mass is explained simply by its large number of neurons. Because synaptic activity is considered the major determinant of metabolic cost, a conserved energy budget per neuron has several profound implications for synaptic homeostasis and the regulation of firing rates, synaptic plasticity, brain imaging, pathologies, and for brain scaling in evolution. PMID:21390261

  16. Inhibition of Non Canonical HIV-1 Tat Secretion Through the Cellular Na+,K+-ATPase Blocks HIV-1 Infection

    Directory of Open Access Journals (Sweden)

    Silvia Agostini

    2017-07-01

    Full Text Available Besides its essential role in the activation of HIV-1 gene expression, the viral Tat protein has the unusual property of trafficking in and out of cells. In contrast to Tat internalization, the mechanism involved in extracellular Tat release has so far remained elusive. Here we show that Tat secretion occurs through a Golgi-independent pathway requiring binding of Tat with three short, non-consecutive intracytoplasmic loops at the C-terminus of the cellular Na+,K+-ATPase pump alpha subunit. Ouabain, a pump inhibitor, blocked this interaction and prevented Tat secretion; virions produced in the presence of this drug were less infectious, consistent the capacity of virion-associated Tat to increase HIV-1 infectivity. Treatment of CD4+ T-cells with short peptides corresponding to the Tat-binding regions of the pump alpha subunit impaired extracellular Tat release and blocked HIV-1 replication. Thus, non canonical, extracellular Tat secretion is essential for viral infectivity.

  17. HIV-1 tat protein recruits CIS to the cytoplasmic tail of CD127 to induce receptor ubiquitination and proteasomal degradation

    Energy Technology Data Exchange (ETDEWEB)

    Sugden, Scott, E-mail: scott.sugden@ircm.qc.ca [The Ottawa Hospital Research Institute, 501 Smyth Road, Ottawa, Ontario, Canada K1H 8L6 (Canada); Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, 451 Smyth Road, Ottawa, Ontario, Canada K1H 8M5 (Canada); Ghazawi, Feras [The Ottawa Hospital Research Institute, 501 Smyth Road, Ottawa, Ontario, Canada K1H 8L6 (Canada); Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, 451 Smyth Road, Ottawa, Ontario, Canada K1H 8M5 (Canada); MacPherson, Paul, E-mail: pmacpherson@toh.on.ca [The Ottawa Hospital Research Institute, 501 Smyth Road, Ottawa, Ontario, Canada K1H 8L6 (Canada); Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, 451 Smyth Road, Ottawa, Ontario, Canada K1H 8M5 (Canada); Division of Infectious Diseases, The Ottawa Hospital General Campus, 501 Smyth Road, Ottawa, Ontario, Canada K1H 8L6 (Canada)

    2016-11-15

    HIV-1 Tat protein down regulates expression of the IL-7 receptor alpha-chain (CD127) from the surface of CD8 T cells resulting in impaired T cell proliferation and cytolytic capacity. We have previously shown that soluble Tat protein is taken up by CD8 T cells and interacts with the cytoplasmic tail of CD127 to induce receptor degradation. The N-terminal domain of Tat interacts with CD127 while the basic domain directs CD127 to the proteasome. We have also shown that upon IL-7 binding to its receptor, CD127 is phosphorylated resulting in CIS-mediated proteasomal degradation. Here, we show that Tat mimics this process by recruiting CIS to CD127 in the absence of IL-7 and receptor phosphorylation, leading to CD127 ubiquitination and degradation. Tat therefore acts as an adapter to induce cellular responses under conditions where they may not otherwise occur. Thusly, Tat reduces IL-7 signaling and impairs CD8 T cell survival and function. -- Highlights: •Soluble HIV-1 Tat decreases CD127 expression on CD8 T cells, causing dysfunction. •Tat induces CD127 ubiquitination without activating IL-7 signaling. •Tat binds CD127 and recruits the E3 ubiquitin ligase CIS via its basic domain. •Tat hijacks a normal cellular mechanism to degrade CD127 without IL-7 signaling.

  18. HIV-1 tat protein recruits CIS to the cytoplasmic tail of CD127 to induce receptor ubiquitination and proteasomal degradation

    International Nuclear Information System (INIS)

    Sugden, Scott; Ghazawi, Feras; MacPherson, Paul

    2016-01-01

    HIV-1 Tat protein down regulates expression of the IL-7 receptor alpha-chain (CD127) from the surface of CD8 T cells resulting in impaired T cell proliferation and cytolytic capacity. We have previously shown that soluble Tat protein is taken up by CD8 T cells and interacts with the cytoplasmic tail of CD127 to induce receptor degradation. The N-terminal domain of Tat interacts with CD127 while the basic domain directs CD127 to the proteasome. We have also shown that upon IL-7 binding to its receptor, CD127 is phosphorylated resulting in CIS-mediated proteasomal degradation. Here, we show that Tat mimics this process by recruiting CIS to CD127 in the absence of IL-7 and receptor phosphorylation, leading to CD127 ubiquitination and degradation. Tat therefore acts as an adapter to induce cellular responses under conditions where they may not otherwise occur. Thusly, Tat reduces IL-7 signaling and impairs CD8 T cell survival and function. -- Highlights: •Soluble HIV-1 Tat decreases CD127 expression on CD8 T cells, causing dysfunction. •Tat induces CD127 ubiquitination without activating IL-7 signaling. •Tat binds CD127 and recruits the E3 ubiquitin ligase CIS via its basic domain. •Tat hijacks a normal cellular mechanism to degrade CD127 without IL-7 signaling.

  19. Inhibition of GABAergic Neurotransmission by HIV-1 Tat and Opioid Treatment in the Striatum Involves μ-opioid Receptors

    Directory of Open Access Journals (Sweden)

    Changqing Xu

    2016-11-01

    Full Text Available Due to combined antiretroviral therapy (cART, human immunodeficiency virus type 1 (HIV-1 is considered a chronic disease with high prevalence of mild forms of neurocognitive impairments, also referred to as HIV-associated neurocognitive disorders (HAND. Although opiate drug use can exacerbate HIV-1 Tat-induced neuronal damage, it remains unknown how and to what extent opioids interact with Tat on the GABAergic system. We conducted whole-cell recordings in mouse striatal slices and examined the effects of HIV-1 Tat in the presence and absence of morphine (1 μM and damgo (1 μM on GABAergic neurotransmission. Results indicated a decrease in the frequency and amplitude of spontaneous inhibitory postsynaptic currents (sIPSCs and miniature IPSCs (mIPSCs by Tat (5 – 50 nM in a concentration-dependent manner. The significant Tat-induced decrease in IPSCs was abolished when removing extracellular and/or intracellular calcium. Treatment with morphine or damgo alone significantly decreased the frequency, but not amplitude of IPSCs. Interestingly, morphine but not damgo indicated an additional downregulation of the mean frequency of mIPSCs in combination with Tat. Pretreatment with naloxone (1 μM and CTAP (1 μM prevented the Tat-induced decrease in sIPSCs frequency but only naloxone prevented the combined Tat and morphine effect on mIPSCs frequency. Results indicate a Tat- or opioid-induced decrease in GABAergic neurotransmission via µ-opioid receptors with combined Tat and morphine effects involving additional opioid receptor-related mechanisms. Exploring the interactions between Tat and opioids on the GABAergic system may help to guide future research on HAND in the context of opiate drug use.

  20. Neuronal Population Activity in Spinal Motor Circuits

    DEFF Research Database (Denmark)

    Berg, Rune W.

    2017-01-01

    The core elements of stereotypical movements such as locomotion, scratching and breathing are generated by networks in the lower brainstem and the spinal cord. Ensemble activities in spinal motor networks had until recently been merely a black box, but with the emergence of ultra-thin Silicon multi......-electrode technology it was possible to reveal the spiking activity of larger parts of the network. A series of experiments revealed unexpected features of spinal networks, such as multiple spiking regimes and lognormal firing rate distributions. The lognormality renders the widespread idea of a typical firing rate...

  1. Human temporal cortical single neuron activity during working memory maintenance.

    Science.gov (United States)

    Zamora, Leona; Corina, David; Ojemann, George

    2016-06-01

    The Working Memory model of human memory, first introduced by Baddeley and Hitch (1974), has been one of the most influential psychological constructs in cognitive psychology and human neuroscience. However the neuronal correlates of core components of this model have yet to be fully elucidated. Here we present data from two studies where human temporal cortical single neuron activity was recorded during tasks differentially affecting the maintenance component of verbal working memory. In Study One we vary the presence or absence of distracting items for the entire period of memory storage. In Study Two we vary the duration of storage so that distractors filled all, or only one-third of the time the memory was stored. Extracellular single neuron recordings were obtained from 36 subjects undergoing awake temporal lobe resections for epilepsy, 25 in Study one, 11 in Study two. Recordings were obtained from a total of 166 lateral temporal cortex neurons during performance of one of these two tasks, 86 study one, 80 study two. Significant changes in activity with distractor manipulation were present in 74 of these neurons (45%), 38 Study one, 36 Study two. In 48 (65%) of those there was increased activity during the period when distracting items were absent, 26 Study One, 22 Study Two. The magnitude of this increase was greater for Study One, 47.6%, than Study Two, 8.1%, paralleling the reduction in memory errors in the absence of distracters, for Study One of 70.3%, Study Two 26.3% These findings establish that human lateral temporal cortex is part of the neural system for working memory, with activity during maintenance of that memory that parallels performance, suggesting it represents active rehearsal. In 31 of these neurons (65%) this activity was an extension of that during working memory encoding that differed significantly from the neural processes recorded during overt and silent language tasks without a recent memory component, 17 Study one, 14 Study two

  2. Human Temporal Cortical Single Neuron Activity During Working Memory Maintenance

    Science.gov (United States)

    Zamora, Leona; Corina, David; Ojemann, George

    2016-01-01

    The Working Memory model of human memory, first introduced by Baddeley and Hitch (1974), has been one of the most influential psychological constructs in cognitive psychology and human neuroscience. However the neuronal correlates of core components of this model have yet to be fully elucidated. Here we present data from two studies where human temporal cortical single neuron activity was recorded during tasks differentially affecting the maintenance component of verbal working memory. In Study One we vary the presence or absence of distracting items for the entire period of memory storage. In Study Two we vary the duration of storage so that distractors filled all, or only one-third of the time the memory was stored. Extracellular single neuron recordings were obtained from 36 subjects undergoing awake temporal lobe resections for epilepsy, 25 in Study one, 11 in Study two. Recordings were obtained from a total of 166 lateral temporal cortex neurons during performance of one of these two tasks, 86 study one, 80 study two. Significant changes in activity with distractor manipulation were present in 74 of these neurons (45%), 38 Study one, 36 Study two. In 48 (65%) of those there was increased activity during the period when distracting items were absent, 26 Study One, 22 Study Two. The magnitude of this increase was greater for Study One, 47.6%, than Study Two, 8.1%, paralleling the reduction in memory errors in the absence of distracters, for Study One of 70.3%, Study Two 26.3% These findings establish that human lateral temporal cortex is part of the neural system for working memory, with activity during maintenance of that memory that parallels performance, suggesting it represents active rehearsal. In 31 of these neurons (65%) this activity was an extension of that during working memory encoding that differed significantly from the neural processes recorded during overt and silent language tasks without a recent memory component, 17 Study one, 14 Study two

  3. Potent inhibition of HIV-1 replication by a Tat mutant.

    Directory of Open Access Journals (Sweden)

    Luke W Meredith

    Full Text Available Herein we describe a mutant of the two-exon HIV-1 Tat protein, termed Nullbasic, that potently inhibits multiple steps of the HIV-1 replication cycle. Nullbasic was created by replacing the entire arginine-rich basic domain of wild type Tat with glycine/alanine residues. Like similarly mutated one-exon Tat mutants, Nullbasic exhibited transdominant negative effects on Tat-dependent transactivation. However, unlike previously reported mutants, we discovered that Nullbasic also strongly suppressed the expression of unspliced and singly-spliced viral mRNA, an activity likely caused by redistribution and thus functional inhibition of HIV-1 Rev. Furthermore, HIV-1 virion particles produced by cells expressing Nullbasic had severely reduced infectivity, a defect attributable to a reduced ability of the virions to undergo reverse transcription. Combination of these inhibitory effects on transactivation, Rev-dependent mRNA transport and reverse transcription meant that permissive cells constitutively expressing Nullbasic were highly resistant to a spreading infection by HIV-1. Nullbasic and its activities thus provide potential insights into the development of potent antiviral therapeutics that target multiple stages of HIV-1 infection.

  4. Direct evidence for activity-dependent glucose phosphorylation in neurons with implications for the astrocyte-to-neuron lactate shuttle.

    Science.gov (United States)

    Patel, Anant B; Lai, James C K; Chowdhury, Golam M I; Hyder, Fahmeed; Rothman, Douglas L; Shulman, Robert G; Behar, Kevin L

    2014-04-08

    Previous (13)C magnetic resonance spectroscopy experiments have shown that over a wide range of neuronal activity, approximately one molecule of glucose is oxidized for every molecule of glutamate released by neurons and recycled through astrocytic glutamine. The measured kinetics were shown to agree with the stoichiometry of a hypothetical astrocyte-to-neuron lactate shuttle model, which predicted negligible functional neuronal uptake of glucose. To test this model, we measured the uptake and phosphorylation of glucose in nerve terminals isolated from rats infused with the glucose analog, 2-fluoro-2-deoxy-D-glucose (FDG) in vivo. The concentrations of phosphorylated FDG (FDG6P), normalized with respect to known neuronal metabolites, were compared in nerve terminals, homogenate, and cortex of anesthetized rats with and without bicuculline-induced seizures. The increase in FDG6P in nerve terminals agreed well with the increase in cortical neuronal glucose oxidation measured previously under the same conditions in vivo, indicating that direct uptake and oxidation of glucose in nerve terminals is substantial under resting and activated conditions. These results suggest that neuronal glucose-derived pyruvate is the major oxidative fuel for activated neurons, not lactate-derived from astrocytes, contradicting predictions of the original astrocyte-to-neuron lactate shuttle model under the range of study conditions.

  5. In vitro assessment of TAT — Ciliary Neurotrophic Factor therapeutic potential for peripheral nerve regeneration

    International Nuclear Information System (INIS)

    Barbon, Silvia; Stocco, Elena; Negro, Alessandro; Dalzoppo, Daniele; Borgio, Luca; Rajendran, Senthilkumar; Grandi, Francesca; Porzionato, Andrea; Macchi, Veronica; De Caro, Raffaele

    2016-01-01

    In regenerative neurobiology, Ciliary Neurotrophic Factor (CNTF) is raising high interest as a multifunctional neurocytokine, playing a key role in the regeneration of injured peripheral nerves. Despite its promising trophic and regulatory activity, its clinical application is limited by the onset of severe side effects, due to the lack of efficient intracellular trafficking after administration. In this study, recombinant CNTF linked to the transactivator transduction domain (TAT) was investigated in vitro and found to be an optimized fusion protein which preserves neurotrophic activity, besides enhancing cellular uptake for therapeutic advantage. Moreover, a compelling protein delivery method was defined, in the future perspective of improving nerve regeneration strategies. Following determination of TAT-CNTF molecular weight and concentration, its specific effect on neural SH-SY5Y and PC12 cultures was assessed. Cell proliferation assay demonstrated that the fusion protein triggers PC12 cell growth within 6 h of stimulation. At the same time, the activation of signal transduction pathway and enhancement of cellular trafficking were found to be accomplished in both neural cell lines after specific treatment with TAT-CNTF. Finally, the recombinant growth factor was successfully loaded on oxidized polyvinyl alcohol (PVA) scaffolds, and more efficiently released when polymer oxidation rate increased. Taken together, our results highlight that the TAT domain addiction to the protein sequence preserves CNTF specific neurotrophic activity in vitro, besides improving cellular uptake. Moreover, oxidized PVA could represent an ideal biomaterial for the development of nerve conduits loaded with the fusion protein to be delivered to the site of nerve injury. - Highlights: • TAT-CNTF is an optimized fusion protein that preserves neurotrophic activity. • In neural cell lines, TAT-CNTF triggers the activation of signal transduction. • Fast cellular uptake of TAT-CNTF was

  6. In vitro assessment of TAT — Ciliary Neurotrophic Factor therapeutic potential for peripheral nerve regeneration

    Energy Technology Data Exchange (ETDEWEB)

    Barbon, Silvia, E-mail: silvia.barbon@yahoo.it [Department of Pharmaceutical and Pharmacological Sciences, University of Padua, Via Marzolo 5, 35131 Padua (Italy); Foundation for Biology and Regenerative Medicine, Tissue Engineering and Signaling (TES) ONLUS, Via De Sanctis 10, Caselle di Selvazzano Dentro, 35030 Padua (Italy); Stocco, Elena, E-mail: elena.stocco@gmail.com [Department of Pharmaceutical and Pharmacological Sciences, University of Padua, Via Marzolo 5, 35131 Padua (Italy); Foundation for Biology and Regenerative Medicine, Tissue Engineering and Signaling (TES) ONLUS, Via De Sanctis 10, Caselle di Selvazzano Dentro, 35030 Padua (Italy); Negro, Alessandro, E-mail: alessandro.negro@unipd.it [Department of Biomedical Sciences, University of Padova, Via Colombo 3, 35121 Padua (Italy); Dalzoppo, Daniele, E-mail: daniele.dalzoppo@unipd.it [Department of Pharmaceutical and Pharmacological Sciences, University of Padua, Via Marzolo 5, 35131 Padua (Italy); Borgio, Luca, E-mail: borgio.luca@gmail.com [Department of Pharmaceutical and Pharmacological Sciences, University of Padua, Via Marzolo 5, 35131 Padua (Italy); Rajendran, Senthilkumar, E-mail: senthilstem@gmail.com [Department of Pharmaceutical and Pharmacological Sciences, University of Padua, Via Marzolo 5, 35131 Padua (Italy); Grandi, Francesca, E-mail: francesca.grandi7825@gmail.com [Department of Women' s and Children' s Health, Pediatric Surgery, University of Padua, Via Giustiniani 3, 35121 Padua (Italy); Porzionato, Andrea, E-mail: andrea.porzionato@unipd.it [Section of Human Anatomy, Department of Molecular Medicine, University of Padua, Via Gabelli 65, 35121 Padua (Italy); Macchi, Veronica, E-mail: veronica.macchi@unipd.it [Section of Human Anatomy, Department of Molecular Medicine, University of Padua, Via Gabelli 65, 35121 Padua (Italy); De Caro, Raffaele, E-mail: raffaele.decaro@unipd.it [Section of Human Anatomy, Department of Molecular Medicine, University of Padua, Via Gabelli 65, 35121 Padua (Italy); and others

    2016-10-15

    In regenerative neurobiology, Ciliary Neurotrophic Factor (CNTF) is raising high interest as a multifunctional neurocytokine, playing a key role in the regeneration of injured peripheral nerves. Despite its promising trophic and regulatory activity, its clinical application is limited by the onset of severe side effects, due to the lack of efficient intracellular trafficking after administration. In this study, recombinant CNTF linked to the transactivator transduction domain (TAT) was investigated in vitro and found to be an optimized fusion protein which preserves neurotrophic activity, besides enhancing cellular uptake for therapeutic advantage. Moreover, a compelling protein delivery method was defined, in the future perspective of improving nerve regeneration strategies. Following determination of TAT-CNTF molecular weight and concentration, its specific effect on neural SH-SY5Y and PC12 cultures was assessed. Cell proliferation assay demonstrated that the fusion protein triggers PC12 cell growth within 6 h of stimulation. At the same time, the activation of signal transduction pathway and enhancement of cellular trafficking were found to be accomplished in both neural cell lines after specific treatment with TAT-CNTF. Finally, the recombinant growth factor was successfully loaded on oxidized polyvinyl alcohol (PVA) scaffolds, and more efficiently released when polymer oxidation rate increased. Taken together, our results highlight that the TAT domain addiction to the protein sequence preserves CNTF specific neurotrophic activity in vitro, besides improving cellular uptake. Moreover, oxidized PVA could represent an ideal biomaterial for the development of nerve conduits loaded with the fusion protein to be delivered to the site of nerve injury. - Highlights: • TAT-CNTF is an optimized fusion protein that preserves neurotrophic activity. • In neural cell lines, TAT-CNTF triggers the activation of signal transduction. • Fast cellular uptake of TAT-CNTF was

  7. Inhibition of GABAergic Neurotransmission by HIV-1 Tat and Opioid Treatment in the Striatum Involves ?-Opioid Receptors

    OpenAIRE

    Xu, Changqing; Fitting, Sylvia

    2016-01-01

    Due to combined antiretroviral therapy (cART), human immunodeficiency virus type 1 (HIV-1) is considered a chronic disease with high prevalence of mild forms of neurocognitive impairments, also referred to as HIV-associated neurocognitive disorders (HAND). Although opiate drug use can exacerbate HIV-1 Tat-induced neuronal damage, it remains unknown how and to what extent opioids interact with Tat on the GABAergic system. We conducted whole-cell recordings in mouse striatal slices and examined...

  8. Neuronal Functions of Activators of G Protein Signaling

    Directory of Open Access Journals (Sweden)

    Man K. Tse

    2012-05-01

    Full Text Available G protein-coupled receptors (GPCRs are one of the most important gateways for signal transduction across the plasma membrane. Over the past decade, several classes of alternative regulators of G protein signaling have been identified and reported to activate the G proteins independent of the GPCRs. One group of such regulators is the activator of G protein signaling (AGS family which comprises of AGS1-10. They have entirely different activation mechanisms for G proteins as compared to the classic model of GPCR-mediated signaling and confer upon cells new avenues of signal transduction. As GPCRs are widely expressed in our nervous system, it is believed that the AGS family plays a major role in modulating the G protein signaling in neurons. In this article, we will review the current knowledge on AGS proteins in relation to their potential roles in neuronal regulations.

  9. A Discrete Population of Neurons in the Lateral Amygdala Is Specifically Activated by Contextual Fear Conditioning

    Science.gov (United States)

    Wilson, Yvette M.; Murphy, Mark

    2009-01-01

    There is no clear identification of the neurons involved in fear conditioning in the amygdala. To search for these neurons, we have used a genetic approach, the "fos-tau-lacZ" (FTL) mouse, to map functionally activated expression in neurons following contextual fear conditioning. We have identified a discrete population of neurons in the lateral…

  10. Activity deprivation induces neuronal cell death: mediation by tissue-type plasminogen activator.

    Directory of Open Access Journals (Sweden)

    Eldi Schonfeld-Dado

    Full Text Available Spontaneous activity is an essential attribute of neuronal networks and plays a critical role in their development and maintenance. Upon blockade of activity with tetrodotoxin (TTX, neurons degenerate slowly and die in a manner resembling neurodegenerative diseases-induced neuronal cell death. The molecular cascade leading to this type of slow cell death is not entirely clear. Primary post-natal cortical neurons were exposed to TTX for up to two weeks, followed by molecular, biochemical and immunefluorescence analysis. The expression of the neuronal marker, neuron specific enolase (NSE, was down-regulated, as expected, but surprisingly, there was a concomitant and striking elevation in expression of tissue-type plasminogen activator (tPA. Immunofluorescence analysis indicated that tPA was highly elevated inside affected neurons. Transfection of an endogenous tPA inhibitor, plasminogen activator inhibitor-1 (PAI-1, protected the TTX-exposed neurons from dying. These results indicate that tPA is a pivotal player in slowly progressing activity deprivation-induced neurodegeneration.

  11. Linking neuronal brain activity to the glucose metabolism.

    Science.gov (United States)

    Göbel, Britta; Oltmanns, Kerstin M; Chung, Matthias

    2013-08-29

    Energy homeostasis ensures the functionality of the entire organism. The human brain as a missing link in the global regulation of the complex whole body energy metabolism is subject to recent investigation. The goal of this study is to gain insight into the influence of neuronal brain activity on cerebral and peripheral energy metabolism. In particular, the tight link between brain energy supply and metabolic responses of the organism is of interest. We aim to identifying regulatory elements of the human brain in the whole body energy homeostasis. First, we introduce a general mathematical model describing the human whole body energy metabolism. It takes into account the two central roles of the brain in terms of energy metabolism. The brain is considered as energy consumer as well as regulatory instance. Secondly, we validate our mathematical model by experimental data. Cerebral high-energy phosphate content and peripheral glucose metabolism are measured in healthy men upon neuronal activation induced by transcranial direct current stimulation versus sham stimulation. By parameter estimation we identify model parameters that provide insight into underlying neurophysiological processes. Identified parameters reveal effects of neuronal activity on regulatory mechanisms of systemic glucose metabolism. Our examinations support the view that the brain increases its glucose supply upon neuronal activation. The results indicate that the brain supplies itself with energy according to its needs, and preeminence of cerebral energy supply is reflected. This mechanism ensures balanced cerebral energy homeostasis. The hypothesis of the central role of the brain in whole body energy homeostasis as active controller is supported.

  12. Molecular and functional differences in voltage-activated sodium currents between GABA projection neurons and dopamine neurons in the substantia nigra

    OpenAIRE

    Ding, Shengyuan; Wei, Wei; Zhou, Fu-Ming

    2011-01-01

    GABA projection neurons (GABA neurons) in the substantia nigra pars reticulata (SNr) and dopamine projection neurons (DA neurons) in substantia nigra pars compacta (SNc) have strikingly different firing properties. SNc DA neurons fire low-frequency, long-duration spikes, whereas SNr GABA neurons fire high-frequency, short-duration spikes. Since voltage-activated sodium (NaV) channels are critical to spike generation, the different firing properties raise the possibility that, compared with DA...

  13. Transient extracellular application of gold nanostars increases hippocampal neuronal activity.

    Science.gov (United States)

    Salinas, Kirstie; Kereselidze, Zurab; DeLuna, Frank; Peralta, Xomalin G; Santamaria, Fidel

    2014-08-20

    With the increased use of nanoparticles in biomedical applications there is a growing need to understand the effects that nanoparticles may have on cell function. Identifying these effects and understanding the mechanism through which nanoparticles interfere with the normal functioning of a cell is necessary for any therapeutic or diagnostic application. The aim of this study is to evaluate if gold nanoparticles can affect the normal function of neurons, namely their activity and coding properties. We synthesized star shaped gold nanoparticles of 180 nm average size. We applied the nanoparticles to acute mouse hippocampal slices while recording the action potentials from single neurons in the CA3 region. Our results show that CA3 hippocampal neurons increase their firing rate by 17% after the application of gold nanostars. The increase in excitability lasted for as much as 50 minutes after a transient 5 min application of the nanoparticles. Further analyses of the action potential shape and computational modeling suggest that nanoparticles block potassium channels responsible for the repolarization of the action potentials, thus allowing the cell to increase its firing rate. Our results show that gold nanoparticles can affect the coding properties of neurons by modifying their excitability.

  14. Collective excitability in a mesoscopic neuronal model of epileptic activity

    Science.gov (United States)

    Jedynak, Maciej; Pons, Antonio J.; Garcia-Ojalvo, Jordi

    2018-01-01

    At the mesoscopic scale, the brain can be understood as a collection of interacting neuronal oscillators, but the extent to which its sustained activity is due to coupling among brain areas is still unclear. Here we address this issue in a simplified situation by examining the effect of coupling between two cortical columns described via Jansen-Rit neural mass models. Our results show that coupling between the two neuronal populations gives rise to stochastic initiations of sustained collective activity, which can be interpreted as epileptic events. For large enough coupling strengths, termination of these events results mainly from the emergence of synchronization between the columns, and thus it is controlled by coupling instead of noise. Stochastic triggering and noise-independent durations are characteristic of excitable dynamics, and thus we interpret our results in terms of collective excitability.

  15. Bioluminescence Monitoring of Neuronal Activity in Freely Moving Zebrafish Larvae

    Science.gov (United States)

    Knafo, Steven; Prendergast, Andrew; Thouvenin, Olivier; Figueiredo, Sophie Nunes; Wyart, Claire

    2017-01-01

    The proof of concept for bioluminescence monitoring of neural activity in zebrafish with the genetically encoded calcium indicator GFP-aequorin has been previously described (Naumann et al., 2010) but challenges remain. First, bioluminescence signals originating from a single muscle fiber can constitute a major pitfall. Second, bioluminescence signals emanating from neurons only are very small. To improve signals while verifying specificity, we provide an optimized 4 steps protocol achieving: 1) selective expression of a zebrafish codon-optimized GFP-aequorin, 2) efficient soaking of larvae in GFP-aequorin substrate coelenterazine, 3) bioluminescence monitoring of neural activity from motor neurons in free-tailed moving animals performing acoustic escapes and 4) verification of the absence of muscle expression using immunohistochemistry. PMID:29130058

  16. The human immunodeficiency virus-1 protein Tat and its discrete fragments evoke selective release of acetylcholine from human and rat cerebrocortical terminals through species-specific mechanisms.

    Science.gov (United States)

    Feligioni, Marco; Raiteri, Luca; Pattarini, Roberto; Grilli, Massimo; Bruzzone, Santina; Cavazzani, Paolo; Raiteri, Maurizio; Pittaluga, Anna

    2003-07-30

    The effect of the human immunodeficiency virus-1 protein Tat was investigated on neurotransmitter release from human and rat cortical nerve endings. Tat failed to affect the release of several neurotransmitters, such as glutamate, GABA, norepinephrine, and others, but it evoked the release of [3H]ACh via increase of cytosolic [Ca2+]. In human nerve terminals, the Tat effect partly depends on Ca2+ entry through voltage-sensitive Ca2+ channels, because Cd2+ halved the Tat-evoked release. Activation of group I metabotropic glutamate receptors (mGluR) and mobilization of Ca2+ from IP3-sensitive intraterminal stores are also involved, because the Tat effect was prevented by mGluR antagonists 2-methyl-6-(phenylethynyl)pyridine hydrochloride and 7-(hydroxyimino)cyclopropa[b]chromen-1a-carboxylate ethyl ester and by the IP3 receptor antagonists heparin and xestospongin C. Furthermore, the group I selective mGlu agonist (RS)-3,5-dihydroxyphenylglycine enhanced [3H]ACh release. In rat nerve terminals, the Tat-evoked release neither depends on external Ca2+ ions entry nor on IP3-mediated mechanisms. Tat seems to cause mobilization of Ca2+ from ryanodine-sensitive internal stores because its effect was prevented by both 8-bromo-cyclic adenosine diphosphate-ribose and dantrolene. The Tat-evoked release from human synaptosomes was mimicked by the peptide sequences Tat 32-62, Tat 49-86, and Tat 41-60. In contrast, the Tat 49-86 and Tat 61-80 fragments, but not the Tat 32-62 fragment, were active in rat synaptosomes. In conclusion, Tat elicits Ca2+-dependent [3H]ACh release by species-specific intraterminal mechanisms by binding via discrete amino acid sequences to different receptive sites on human and rat cholinergic terminals.

  17. Manipulating neuronal activity with low frequency transcranial ultrasound

    Science.gov (United States)

    Moore, Michele Elizabeth

    Stimulation of the rodent cerebral cortex is used to investigate the underlying biological basis for the restorative effects of slow wave sleep. Neuronal activation by optogenetic and ultrasound stimulation elicits changes in action potentials across the cerebral cortex that are recorded as electroencephalograms. Optogenetic stimulation requires an invasive implantation procedure limiting its application in human studies. We sought to determine whether ultrasound stimulation could be as effective as optogenetic techniques currently used, in an effort to further understand the physiological and metabolic requirements of sleep. We successfully recorded electroencephalograms in response to transcranial ultrasound stimulation of the barrel cortex at 1 and 7 Hz frequencies, comparing them to those recorded in response to optogenetic stimuli applied at the same frequencies. Our results showed application of a 473 nm blue LED positioned 6 cm above the skull and ultrasound stimulation at an output voltage of 1000 mVpp produced electroencephalograms with physiological responses of similar amplitude. We concluded that there exists an intensity-proportionate response in the optogenetic stimulation, but not with ultrasound stimulation at the frequencies we surveyed. Activation of neuronal cells in response to optogenetic stimulation in a Thy1-ChR2 transgenic mouse line is specifically targeted to pyramidal cells in the cerebral cortex. ChR2 responses to optogenetic stimulation are mediated by a focal activation of neuronal ion channels. We measured electrophysiological responses to ultrasound stimulation, comparing them to those recorded from optogenetic stimuli. Our results show striking similarities between ultrasound-induced responses and optogenetically-induced responses, which may indicate that transcranial ultrasound stimulation is also mediated by ion channel dependent processes in cerebral cortical neurons. The biophysical substrates for electrical excitability of

  18. Linking neuronal brain activity to the glucose metabolism

    OpenAIRE

    Göbel, Britta; Oltmanns, Kerstin M; Chung, Matthias

    2013-01-01

    Background Energy homeostasis ensures the functionality of the entire organism. The human brain as a missing link in the global regulation of the complex whole body energy metabolism is subject to recent investigation. The goal of this study is to gain insight into the influence of neuronal brain activity on cerebral and peripheral energy metabolism. In particular, the tight link between brain energy supply and metabolic responses of the organism is of interest. We aim to identifying regul...

  19. Activation of Supraoptic Oxytocin Neurons by Secretin Facilitates Social Recognition.

    Science.gov (United States)

    Takayanagi, Yuki; Yoshida, Masahide; Takashima, Akihide; Takanami, Keiko; Yoshida, Shoma; Nishimori, Katsuhiko; Nishijima, Ichiko; Sakamoto, Hirotaka; Yamagata, Takanori; Onaka, Tatsushi

    2017-02-01

    Social recognition underlies social behavior in animals, and patients with psychiatric disorders associated with social deficits show abnormalities in social recognition. Oxytocin is implicated in social behavior and has received attention as an effective treatment for sociobehavioral deficits. Secretin receptor-deficient mice show deficits in social behavior. The relationship between oxytocin and secretin concerning social behavior remains to be determined. Expression of c-Fos in oxytocin neurons and release of oxytocin from their dendrites after secretin application were investigated. Social recognition was examined after intracerebroventricular or local injection of secretin, oxytocin, or an oxytocin receptor antagonist in rats, oxytocin receptor-deficient mice, and secretin receptor-deficient mice. Electron and light microscopic immunohistochemical analysis was also performed to determine whether oxytocin neurons extend their dendrites into the medial amygdala. Supraoptic oxytocin neurons expressed the secretin receptor. Secretin activated supraoptic oxytocin neurons and facilitated oxytocin release from dendrites. Secretin increased acquisition of social recognition in an oxytocin receptor-dependent manner. Local application of secretin into the supraoptic nucleus facilitated social recognition, and this facilitation was blocked by an oxytocin receptor antagonist injected into, but not outside of, the medial amygdala. In the medial amygdala, dendrite-like thick oxytocin processes were found to extend from the supraoptic nucleus. Furthermore, oxytocin treatment restored deficits of social recognition in secretin receptor-deficient mice. The results of our study demonstrate that secretin-induced dendritic oxytocin release from supraoptic neurons enhances social recognition. The newly defined secretin-oxytocin system may lead to a possible treatment for social deficits. Copyright © 2016 Society of Biological Psychiatry. Published by Elsevier Inc. All rights

  20. Serotonin neurons in the dorsal raphe mediate the anticataplectic action of orexin neurons by reducing amygdala activity.

    Science.gov (United States)

    Hasegawa, Emi; Maejima, Takashi; Yoshida, Takayuki; Masseck, Olivia A; Herlitze, Stefan; Yoshioka, Mitsuhiro; Sakurai, Takeshi; Mieda, Michihiro

    2017-04-25

    Narcolepsy is a sleep disorder caused by the loss of orexin (hypocretin)-producing neurons and marked by excessive daytime sleepiness and a sudden weakening of muscle tone, or cataplexy, often triggered by strong emotions. In a mouse model for narcolepsy, we previously demonstrated that serotonin neurons of the dorsal raphe nucleus (DRN) mediate the suppression of cataplexy-like episodes (CLEs) by orexin neurons. Using an optogenetic tool, in this paper we show that the acute activation of DRN serotonin neuron terminals in the amygdala, but not in nuclei involved in regulating rapid eye-movement sleep and atonia, suppressed CLEs. Not only did stimulating serotonin nerve terminals reduce amygdala activity, but the chemogenetic inhibition of the amygdala using designer receptors exclusively activated by designer drugs also drastically decreased CLEs, whereas chemogenetic activation increased them. Moreover, the optogenetic inhibition of serotonin nerve terminals in the amygdala blocked the anticataplectic effects of orexin signaling in DRN serotonin neurons. Taken together, the results suggest that DRN serotonin neurons, as a downstream target of orexin neurons, inhibit cataplexy by reducing the activity of amygdala as a center for emotional processing.

  1. HIV-1 Tat reduces nephrin in human podocytes: a potential mechanism for enhanced glomerular permeability in HIV-associated nephropathy.

    Science.gov (United States)

    Doublier, Sophie; Zennaro, Cristina; Spatola, Tiziana; Lupia, Enrico; Bottelli, Antonella; Deregibus, Maria Chiara; Carraro, Michele; Conaldi, Pier Giulio; Camussi, Giovanni

    2007-02-19

    To determine whether HIV-1 Tat may directly alter glomerular permeability in HIV-associated nephropathy (HIVAN). Heavy proteinuria is a hallmark of HIVAN. The slit diaphragm is the ultimate glomerular filtration barrier critical for maintaining the efficiency of the ultrafiltration unit of the kidney. In this study, we evaluated the direct effect of Tat protein on the permeability of isolated glomeruli and on the expression of nephrin, the main slit diaphragm component, by human cultured podocytes. Permeability was studied by measuring the permeability to albumin in isolated rat glomeruli. We also evaluated the expression of nephrin in human cultured podocytes by using immunofluorescence and Western blot. We found that Tat increased albumin permeability in isolated glomeruli, and rapidly induced the redistribution and loss of nephrin in cultured podocytes. Pretreatment of glomeruli and podocytes with blocking antibodies showed that Tat reduced nephrin expression by engaging vascular endothelial growth factor receptors types 2 and 3 and the integrin alphavbeta3. Pre-incubation of podocytes with two platelet-activating factor (PAF) receptor antagonists prevented the loss and redistribution of nephrin induced by Tat, suggesting that PAF is an intracellular mediator of Tat action. Tat induced a rapid PAF synthesis by podocytes. When podocytes transfected to overexpress PAF-acetylhydrolase, the main catabolic enzyme of PAF, were stimulated with Tat, the redistribution and loss of nephrin was abrogated. The present results define a mechanism by which Tat may reduce nephrin expression in podocytes, thus increasing glomerular permeability. This provides new insights in the understanding of HIVAN pathogenesis.

  2. Modulatory Mechanism of Nociceptive Neuronal Activity by Dietary Constituent Resveratrol

    Directory of Open Access Journals (Sweden)

    Mamoru Takeda

    2016-10-01

    Full Text Available Changes to somatic sensory pathways caused by peripheral tissue, inflammation or injury can result in behavioral hypersensitivity and pathological pain, such as hyperalgesia. Resveratrol, a plant polyphenol found in red wine and various food products, is known to have several beneficial biological actions. Recent reports indicate that resveratrol can modulate neuronal excitability, including nociceptive sensory transmission. As such, it is possible that this dietary constituent could be a complementary alternative medicine (CAM candidate, specifically a therapeutic agent. The focus of this review is on the mechanisms underlying the modulatory effects of resveratrol on nociceptive neuronal activity associated with pain relief. In addition, we discuss the contribution of resveratrol to the relief of nociceptive and/or pathological pain and its potential role as a functional food and a CAM.

  3. Activity-Dependent Neurorehabilitation Beyond Physical Trainings: "Mental Exercise" Through Mirror Neuron Activation.

    Science.gov (United States)

    Yuan, Ti-Fei; Chen, Wei; Shan, Chunlei; Rocha, Nuno; Arias-Carrión, Oscar; Paes, Flávia; de Sá, Alberto Souza; Machado, Sergio

    2015-01-01

    The activity dependent brain repair mechanism has been widely adopted in many types of neurorehabilitation. The activity leads to target specific and non-specific beneficial effects in different brain regions, such as the releasing of neurotrophic factors, modulation of the cytokines and generation of new neurons in adult hood. However physical exercise program clinically are limited to some of the patients with preserved motor functions; while many patients suffered from paralysis cannot make such efforts. Here the authors proposed the employment of mirror neurons system in promoting brain rehabilitation by "observation based stimulation". Mirror neuron system has been considered as an important basis for action understanding and learning by mimicking others. During the action observation, mirror neuron system mediated the direct activation of the same group of motor neurons that are responsible for the observed action. The effect is clear, direct, specific and evolutionarily conserved. Moreover, recent evidences hinted for the beneficial effects on stroke patients after mirror neuron system activation therapy. Finally some music-relevant therapies were proposed to be related with mirror neuron system.

  4. The cross-talk of HIV-1 Tat and methamphetamine in HIV-associated neurocognitive disorders

    Directory of Open Access Journals (Sweden)

    Susana T Valente

    2015-10-01

    Full Text Available Antiretroviral therapy (ART has dramatically improved the lives of HIV-1 infected individuals. Nonetheless, HIV associated neurocognitive disorders (HAND, which range from undetectable neurocognitive impairments to severe dementia, still affect approximately 50% of the infected population, hampering their quality of life.The persistence of HAND is promoted by several factors, including longer life expectancies, the residual levels of virus in the central nervous system and the continued presence of HIV-1 regulatory proteins such as the transactivator of transcription (Tat in the brain. Tat is a secreted viral protein that crosses the blood brain barrier into the central nervous system, where it has the ability to directly act on neurons and non-neuronal cells alike. These actions result in the release of soluble factors involved in inflammation, oxidative stress and excitotoxicity, ultimately resulting in neuronal damage. The percentage of methamphetamine abusers is high among the HIV-1-positive population compared to the general population. On the other hand, methamphetamine abuse is correlated with increased viral replication, enhanced Tat-mediated neurotoxicity and neurocognitive impairments. Although several strategies have been investigated to reduce HAND and methamphetamine use, no clinically approved treatment is currently available. Here, we review the latest findings of the effects of Tat and methamphetamine in HAND and discuss a few promising potential therapeutic developments.

  5. A real-time view of the TAR:Tat:P-TEFb complex at HIV-1 transcription sites

    Directory of Open Access Journals (Sweden)

    Knezevich Anna

    2007-05-01

    Full Text Available Abstract HIV-1 transcription is tightly regulated: silent in long-term latency and highly active in acutely-infected cells. Transcription is activated by the viral protein Tat, which recruits the elongation factor P-TEFb by binding the TAR sequence present in nascent HIV-1 RNAs. In this study, we analyzed the dynamic of the TAR:Tat:P-TEFb complex in living cells, by performing FRAP experiments at HIV-1 transcription sites. Our results indicate that a large fraction of Tat present at these sites is recruited by Cyclin T1. We found that in the presence of Tat, Cdk9 remained bound to nascent HIV-1 RNAs for 71s. In contrast, when transcription was activated by PMA/ionomycin, in the absence of Tat, Cdk9 turned-over rapidly and resided on the HIV-1 promoter for only 11s. Thus, the mechanism of trans-activation determines the residency time of P-TEFb at the HIV-1 gene, possibly explaining why Tat is such a potent transcriptional activator. In addition, we observed that Tat occupied HIV-1 transcription sites for 55s, suggesting that the TAR:Tat:P-TEFb complex dissociates from the polymerase following transcription initiation, and undergoes subsequent cycles of association/dissociation.

  6. Improved intracellular delivery of glucocerebrosidase mediated by the HIV-1 TAT protein transduction domain

    International Nuclear Information System (INIS)

    Lee, Kyun Oh; Luu, Nga; Kaneski, Christine R.; Schiffmann, Raphael; Brady, Roscoe O.; Murray, Gary J.

    2005-01-01

    Enzyme replacement therapy (ERT) for Gaucher disease designed to target glucocerebrosidase (GC) to macrophages via mannose-specific endocytosis is very effective in reversing hepatosplenomegaly, and normalizing hematologic parameters but is less effective in improving bone and lung involvement and ineffective in brain. Recombinant GCs containing an in-frame fusion to the HIV-1 trans-activator protein transduction domain (TAT) were expressed in eukaryotic cells in order to obtain active, normally glycosylated GC fusion proteins for enzyme uptake studies. Despite the absence of mannose-specific endocytic receptors on the plasma membranes of various fibroblasts, the recombinant GCs with C-terminal TAT fusions were readily internalized by these cells. Immunofluorescent confocal microscopy demonstrated the recombinant TAT-fusion proteins with a mixed endosomal and lysosomal localization. Thus, TAT-modified GCs represent a novel strategy for a new generation of therapeutic enzymes for ERT for Gaucher disease

  7. Interaction between HIV-1 Tat and DNA-PKcs modulates HIV transcription and class switch recombination.

    Science.gov (United States)

    Zhang, Shi-Meng; Zhang, He; Yang, Tian-Yi; Ying, Tian-Yi; Yang, Pei-Xiang; Liu, Xiao-Dan; Tang, Sheng-Jian; Zhou, Ping-Kun

    2014-01-01

    HIV-1 tat targets a variety of host cell proteins to facilitate viral transcription and disrupts host cellular immunity by inducing lymphocyte apoptosis, but whether it influences humoral immunity remains unclear. Previously, our group demonstrated that tat depresses expression of DNA-PKcs, a critical component of the non-homologous end joining pathway (NHEJ) of DNA double-strand breaks repair, immunoglobulin class switch recombination (CSR) and V(D)J recombination, and sensitizes cells to ionizing radiation. In this study, we demonstrated that HIV-1 Tat down-regulates DNA-PKcs expression by directly binding to the core promoter sequence. In addition, Tat interacts with and activates the kinase activity of DNA-PKcs in a dose-dependent and DNA independent manner. Furthermore, Tat inhibits class switch recombination (CSR) at low concentrations (≤ 4 µg/ml) and stimulates CSR at high concentrations (≥ 8 µg/ml). On the other hand, low protein level and high kinase activity of DNA-PKcs promotes HIV-1 transcription, while high protein level and low kinase activity inhibit HIV-1 transcription. Co-immunoprecipitation results revealed that DNA-PKcs forms a large complex comprised of Cyclin T1, CDK9 and Tat via direct interacting with CDK9 and Tat but not Cyclin T1. Taken together, our results provide new clues that Tat regulates host humoral immunity via both transcriptional depression and kinase activation of DNA-PKcs. We also raise the possibility that inhibitors and interventions directed towards DNA-PKcs may inhibit HIV-1 transcription in AIDS patients.

  8. Properties of bilateral spinocerebellar activation of cerebellar cortical neurons

    Directory of Open Access Journals (Sweden)

    Pontus eGeborek

    2014-10-01

    Full Text Available We aimed to explore the cerebellar cortical inputs from two spinocerebellar pathways, the spinal border cell-component of the ventral spinocerebellar tract (SBC-VSCT and the dorsal spinocerebellar tract (DSCT, respectively, in the sublobule C1 of the cerebellar posterior lobe. The two pathways were activated by electrical stimulation of the contralateral lateral funiculus (coLF and the ipsilateral LF (iLF at lower thoracic levels. Most granule cells in sublobule C1 did not respond at all but part of the granule cell population displayed high-intensity responses to either coLF or iLF stimulation. As a rule, Golgi cells and Purkinje cell simple spikes responded to input from both LFs, although Golgi cells could be more selective. In addition, a small population of granule cells responded to input from both the coLF and the iLF. However, in these cases, similarities in the temporal topography and magnitude of the responses suggested that the same axons were stimulated from the two LFs, i.e. that the axons of individual spinocerebellar neurons could be present in both funiculi. This was also confirmed for a population of spinal neurons located within known locations of SBC-VSCT neurons and dorsal horn DSCT neurons. We conclude that bilateral spinocerebellar responses can occur in cerebellar granule cells, but the VSCT and DSCT systems that provide the input can also be organized bilaterally. The implications for the traditional functional separation of VSCT and DSCT systems and the issue whether granule cells primarily integrate functionally similar information or not are discussed.

  9. The Limited Utility of Multiunit Data in Differentiating Neuronal Population Activity.

    Directory of Open Access Journals (Sweden)

    Corey J Keller

    Full Text Available To date, single neuron recordings remain the gold standard for monitoring the activity of neuronal populations. Since obtaining single neuron recordings is not always possible, high frequency or 'multiunit activity' (MUA is often used as a surrogate. Although MUA recordings allow one to monitor the activity of a large number of neurons, they do not allow identification of specific neuronal subtypes, the knowledge of which is often critical for understanding electrophysiological processes. Here, we explored whether prior knowledge of the single unit waveform of specific neuron types is sufficient to permit the use of MUA to monitor and distinguish differential activity of individual neuron types. We used an experimental and modeling approach to determine if components of the MUA can monitor medium spiny neurons (MSNs and fast-spiking interneurons (FSIs in the mouse dorsal striatum. We demonstrate that when well-isolated spikes are recorded, the MUA at frequencies greater than 100Hz is correlated with single unit spiking, highly dependent on the waveform of each neuron type, and accurately reflects the timing and spectral signature of each neuron. However, in the absence of well-isolated spikes (the norm in most MUA recordings, the MUA did not typically contain sufficient information to permit accurate prediction of the respective population activity of MSNs and FSIs. Thus, even under ideal conditions for the MUA to reliably predict the moment-to-moment activity of specific local neuronal ensembles, knowledge of the spike waveform of the underlying neuronal populations is necessary, but not sufficient.

  10. Electrical Activity in a Time-Delay Four-Variable Neuron Model under Electromagnetic Induction

    Directory of Open Access Journals (Sweden)

    Keming Tang

    2017-11-01

    Full Text Available To investigate the effect of electromagnetic induction on the electrical activity of neuron, the variable for magnetic flow is used to improve Hindmarsh–Rose neuron model. Simultaneously, due to the existence of time-delay when signals are propagated between neurons or even in one neuron, it is important to study the role of time-delay in regulating the electrical activity of the neuron. For this end, a four-variable neuron model is proposed to investigate the effects of electromagnetic induction and time-delay. Simulation results suggest that the proposed neuron model can show multiple modes of electrical activity, which is dependent on the time-delay and external forcing current. It means that suitable discharge mode can be obtained by selecting the time-delay or external forcing current, which could be helpful for further investigation of electromagnetic radiation on biological neuronal system.

  11. HIV-1 tat promotes integrin-mediated HIV transmission to dendritic cells by binding Env spikes and competes neutralization by anti-HIV antibodies.

    Directory of Open Access Journals (Sweden)

    Paolo Monini

    Full Text Available Use of Env in HIV vaccine development has been disappointing. Here we show that, in the presence of a biologically active Tat subunit vaccine, a trimeric Env protein prevents in monkeys virus spread from the portal of entry to regional lymph nodes. This appears to be due to specific interactions between Tat and Env spikes that form a novel virus entry complex favoring R5 or X4 virus entry and productive infection of dendritic cells (DCs via an integrin-mediated pathway. These Tat effects do not require Tat-transactivation activity and are blocked by anti-integrin antibodies (Abs. Productive DC infection promoted by Tat is associated with a highly efficient virus transmission to T cells. In the Tat/Env complex the cysteine-rich region of Tat engages the Env V3 loop, whereas the Tat RGD sequence remains free and directs the virus to integrins present on DCs. V2 loop deletion, which unshields the CCR5 binding region of Env, increases Tat/Env complex stability. Of note, binding of Tat to Env abolishes neutralization of Env entry or infection of DCs by anti-HIV sera lacking anti-Tat Abs, which are seldom present in natural infection. This is reversed, and neutralization further enhanced, by HIV sera containing anti-Tat Abs such as those from asymptomatic or Tat-vaccinated patients, or by sera from the Tat/Env vaccinated monkeys. Thus, both anti-Tat and anti-Env Abs are required for efficient HIV neutralization. These data suggest that the Tat/Env interaction increases HIV acquisition and spreading, as a mechanism evolved by the virus to escape anti-Env neutralizing Abs. This may explain the low effectiveness of Env-based vaccines, which are also unlikely to elicit Abs against new Env epitopes exposed by the Tat/Env interaction. As Tat also binds Envs from different clades, new vaccine strategies should exploit the Tat/Env interaction for both preventative and therapeutic interventions.

  12. Fast and direct detection of neuronal activation with diffusion MRI

    International Nuclear Information System (INIS)

    Le Bihan, D.; Urayama, S.; Aso, T.; Hanakawa, T.; Fukuyama, H.

    2006-01-01

    Over the last 30 years functional neuroimaging has emerged as a revolutionary path to study the brain and the mind. This has been possible because of significant advances mainly in two imaging modalities, namely Positron Emission Tomograph y (PET) and Magnetic Resonance Imaging (MRI). Amazingly, although those two modalities are based on radically different physical approaches (detection of 1 3 radioactivity for the first one and nuclear magnetization for the second), both allo w brain activation images to be obtained through measurements involving water molecules. So far, PET and MRI functional imaging have relied on the same principle that neuronal activation and blood flow are coupled through metabolism: Blood flow increases locally in activated brain regions. In the case of PET one uses H 2 O radioactive water which is produced by using a cyclotron and injected to the subject vasculature. In activated brain regions the increase in blood flow leads to a local increase in the tissue radioactive water content detected and localized by the PE T camera. With MRI the hydrogen nuclei of brain endogenous water molecules are magnetized by a strong external magnetic field. In activated regions the increase in blood flow results in an increase of blood oxygenation which induces a slight perturbation of the magnetization relaxation properties of the water molecules around blood vessels detected by the MRI scanner (so called 'BOLD' effect). I n both approaches water is, thus, merely an indirect means to look at changes in cerebral blood flow which accompany brain activation, and although PET and BOLD f MRI have been extremely successful for the functional neuroimaging community, present well known limitations. While the coupling between neuronal activation, metabolism and blood flow has been verified in most instances including BOLD f MRI, the degree and the mechanism of coupling remains largely debated (Magistratt, Pellerin, Mangia) and may fail in some pathological

  13. Activation of AMP-activated protein kinase by tributyltin induces neuronal cell death

    International Nuclear Information System (INIS)

    Nakatsu, Yusuke; Kotake, Yaichiro; Hino, Atsuko; Ohta, Shigeru

    2008-01-01

    AMP-activated protein kinase (AMPK), a member of the metabolite-sensing protein kinase family, is activated by energy deficiency and is abundantly expressed in neurons. The environmental pollutant, tributyltin chloride (TBT), is a neurotoxin, and has been reported to decrease cellular ATP in some types of cells. Therefore, we investigated whether TBT activates AMPK, and whether its activation contributes to neuronal cell death, using primary cultures of cortical neurons. Cellular ATP levels were decreased 0.5 h after exposure to 500 nM TBT, and the reduction was time-dependent. It was confirmed that most neurons in our culture system express AMPK, and that TBT induced phosphorylation of AMPK. Compound C, an AMPK inhibitor, reduced the neurotoxicity of TBT, suggesting that AMPK is involved in TBT-induced cell death. Next, the downstream target of AMPK activation was investigated. Nitric oxide synthase, p38 phosphorylation and Akt dephosphorylation were not downstream of TBT-induced AMPK activation because these factors were not affected by compound C, but glutamate release was suggested to be controlled by AMPK. Our results suggest that activation of AMPK by TBT causes neuronal death through mediating glutamate release

  14. Synaptic and intrinsic activation of GABAergic neurons in the cardiorespiratory brainstem network.

    Directory of Open Access Journals (Sweden)

    Julie G Frank

    Full Text Available GABAergic pathways in the brainstem play an essential role in respiratory rhythmogenesis and interactions between the respiratory and cardiovascular neuronal control networks. However, little is known about the identity and function of these GABAergic inhibitory neurons and what determines their activity. In this study we have identified a population of GABAergic neurons in the ventrolateral medulla that receive increased excitatory post-synaptic potentials during inspiration, but also have spontaneous firing in the absence of synaptic input. Using transgenic mice that express GFP under the control of the Gad1 (GAD67 gene promoter, we determined that this population of GABAergic neurons is in close apposition to cardioinhibitory parasympathetic cardiac neurons in the nucleus ambiguus (NA. These neurons fire in synchronization with inspiratory activity. Although they receive excitatory glutamatergic synaptic inputs during inspiration, this excitatory neurotransmission was not altered by blocking nicotinic receptors, and many of these GABAergic neurons continue to fire after synaptic blockade. The spontaneous firing in these GABAergic neurons was not altered by the voltage-gated calcium channel blocker cadmium chloride that blocks both neurotransmission to these neurons and voltage-gated Ca(2+ currents, but spontaneous firing was diminished by riluzole, demonstrating a role of persistent sodium channels in the spontaneous firing in these cardiorespiratory GABAergic neurons that possess a pacemaker phenotype. The spontaneously firing GABAergic neurons identified in this study that increase their activity during inspiration would support respiratory rhythm generation if they acted primarily to inhibit post-inspiratory neurons and thereby release inspiration neurons to increase their activity. This population of inspiratory-modulated GABAergic neurons could also play a role in inhibiting neurons that are most active during expiration and provide a

  15. Synaptic and intrinsic activation of GABAergic neurons in the cardiorespiratory brainstem network.

    Science.gov (United States)

    Frank, Julie G; Mendelowitz, David

    2012-01-01

    GABAergic pathways in the brainstem play an essential role in respiratory rhythmogenesis and interactions between the respiratory and cardiovascular neuronal control networks. However, little is known about the identity and function of these GABAergic inhibitory neurons and what determines their activity. In this study we have identified a population of GABAergic neurons in the ventrolateral medulla that receive increased excitatory post-synaptic potentials during inspiration, but also have spontaneous firing in the absence of synaptic input. Using transgenic mice that express GFP under the control of the Gad1 (GAD67) gene promoter, we determined that this population of GABAergic neurons is in close apposition to cardioinhibitory parasympathetic cardiac neurons in the nucleus ambiguus (NA). These neurons fire in synchronization with inspiratory activity. Although they receive excitatory glutamatergic synaptic inputs during inspiration, this excitatory neurotransmission was not altered by blocking nicotinic receptors, and many of these GABAergic neurons continue to fire after synaptic blockade. The spontaneous firing in these GABAergic neurons was not altered by the voltage-gated calcium channel blocker cadmium chloride that blocks both neurotransmission to these neurons and voltage-gated Ca(2+) currents, but spontaneous firing was diminished by riluzole, demonstrating a role of persistent sodium channels in the spontaneous firing in these cardiorespiratory GABAergic neurons that possess a pacemaker phenotype. The spontaneously firing GABAergic neurons identified in this study that increase their activity during inspiration would support respiratory rhythm generation if they acted primarily to inhibit post-inspiratory neurons and thereby release inspiration neurons to increase their activity. This population of inspiratory-modulated GABAergic neurons could also play a role in inhibiting neurons that are most active during expiration and provide a framework for

  16. Effects of weak electric fields on the activity of neurons and neuronal networks

    International Nuclear Information System (INIS)

    Jeffreys, J.G.R.; Deans, J.; Bikson, M.; Fox, J.

    2003-01-01

    Electric fields applied to brain tissue will affect cellular properties. They will hyperpolarise the ends of cells closest to the positive part of the field, and depolarise ends closest to the negative. In the case of neurons this affects excitability. How these changes in transmembrane potential are distributed depends on the length constant of the neuron, and on its geometry; if the neuron is electrically compact, the change in transmembrane potential becomes an almost linear function of distance in the direction of the field. Neurons from the mammalian hippocampus, maintained in tissue slices in vitro, are significantly affected by fields of around 1-5 Vm -1 . (author)

  17. Direct neuronal glucose uptake Heralds activity-dependent increases in cerebral metabolism

    DEFF Research Database (Denmark)

    Lundgaard, Iben; Li, Baoman; Xie, Lulu

    2015-01-01

    Metabolically, the brain is a highly active organ that relies almost exclusively on glucose as its energy source. According to the astrocyte-to-neuron lactate shuttle hypothesis, glucose is taken up by astrocytes and converted to lactate, which is then oxidized by neurons. Here we show, using two......-photon imaging of a near-infrared 2-deoxyglucose analogue (2DG-IR), that glucose is taken up preferentially by neurons in awake behaving mice. Anaesthesia suppressed neuronal 2DG-IR uptake and sensory stimulation was associated with a sharp increase in neuronal, but not astrocytic, 2DG-IR uptake. Moreover......, hexokinase, which catalyses the first enzymatic steps in glycolysis, was highly enriched in neurons compared with astrocytes, in mouse as well as in human cortex. These observations suggest that brain activity and neuronal glucose metabolism are directly linked, and identify the neuron as the principal locus...

  18. Direct neuronal glucose uptake heralds activity-dependent increases in cerebral metabolism.

    Science.gov (United States)

    Lundgaard, Iben; Li, Baoman; Xie, Lulu; Kang, Hongyi; Sanggaard, Simon; Haswell, John D R; Sun, Wei; Goldman, Siri; Blekot, Solomiya; Nielsen, Michael; Takano, Takahiro; Deane, Rashid; Nedergaard, Maiken

    2015-04-23

    Metabolically, the brain is a highly active organ that relies almost exclusively on glucose as its energy source. According to the astrocyte-to-neuron lactate shuttle hypothesis, glucose is taken up by astrocytes and converted to lactate, which is then oxidized by neurons. Here we show, using two-photon imaging of a near-infrared 2-deoxyglucose analogue (2DG-IR), that glucose is taken up preferentially by neurons in awake behaving mice. Anaesthesia suppressed neuronal 2DG-IR uptake and sensory stimulation was associated with a sharp increase in neuronal, but not astrocytic, 2DG-IR uptake. Moreover, hexokinase, which catalyses the first enzymatic steps in glycolysis, was highly enriched in neurons compared with astrocytes, in mouse as well as in human cortex. These observations suggest that brain activity and neuronal glucose metabolism are directly linked, and identify the neuron as the principal locus of glucose uptake as visualized by functional brain imaging.

  19. Direct neuronal glucose uptake heralds activity-dependent increases in cerebral metabolism

    Science.gov (United States)

    Lundgaard, Iben; Li, Baoman; Xie, Lulu; Kang, Hongyi; Sanggaard, Simon; Haswell, John Douglas R; Sun, Wei; Goldman, Siri; Blekot, Solomiya; Nielsen, Michael; Takano, Takahiro; Deane, Rashid; Nedergaard, Maiken

    2015-01-01

    Metabolically, the brain is a highly active organ that relies almost exclusively on glucose as its energy source. According to the astrocyte-to-neuron lactate shuttle hypothesis, glucose is taken up by astrocytes and converted to lactate, which is then oxidized by neurons. Here we show, using 2-photon imaging of a near-infrared 2-deoxyglucose analogue (2DG-IR), that glucose is taken up preferentially by neurons in awake behaving mice. Anesthesia suppressed neuronal 2DG-IR uptake and sensory stimulation was associated with a sharp increase in neuronal, but not astrocytic, 2DG-IR uptake. Moreover, hexokinase, which catalyze the first enzymatic steps in glycolysis, was highly enriched in neurons compared with astrocytes, in mouse as well as in human cortex. These observations suggest that brain activity and neuronal glucose metabolism are directly linked, and identifies the neuron as the principal locus of glucose uptake as visualized by functional brain imaging. PMID:25904018

  20. The satiety signaling neuropeptide perisulfakinin inhibits the activity of central neurons promoting general activity

    Directory of Open Access Journals (Sweden)

    Dieter Wicher

    2007-12-01

    Full Text Available The metabolic state is one of the determinants of the general activity level. Satiety is related to resting or sleep whereas hunger correlates to wakefulness and activity. The counterpart to the mammalian satiety signal cholecystokinin (CCK in insects are the sulfakinins. The aim of this study was to resolve the mechanism by which the antifeedant activity of perisulfakinin (PSK in Periplaneta americana is mediated. We identified the sources of PSK which is used both as hormone and as paracrine messenger. PSK is found in the neurohemal organ of the brain and in nerve endings throughout the central nervous system. To correlate the distributions of PSK and its receptor (PSKR, we cloned the gene coding for PSKR and provide evidence for its expression within the nervous system. It occurs only in a few neurons, among them are the dorsal unpaired median (DUM neurons which release octopamine thereby regulating the general level of activity. Application of PSK to DUM neurons attenuated the spiking frequency (EC50=11pM due to reduction of a pacemaker Ca2+ current through cAMP-inhibited pTRPγ channels. PSK increased the intracellular cAMP level while decreasing the intracellular Ca2+ concentration in DUM neurons. Thus, the satiety signal conferred by PSK acts antagonistically to the hunger signal, provided by the adipokinetic hormone (AKH: PSK depresses the electrical activity of DUM neurons by inhibiting the pTRPγ channel that is activated by AKH under conditions of food shortage.

  1. Dynamic Control of Synchronous Activity in Networks of Spiking Neurons.

    Directory of Open Access Journals (Sweden)

    Axel Hutt

    Full Text Available Oscillatory brain activity is believed to play a central role in neural coding. Accumulating evidence shows that features of these oscillations are highly dynamic: power, frequency and phase fluctuate alongside changes in behavior and task demands. The role and mechanism supporting this variability is however poorly understood. We here analyze a network of recurrently connected spiking neurons with time delay displaying stable synchronous dynamics. Using mean-field and stability analyses, we investigate the influence of dynamic inputs on the frequency of firing rate oscillations. We show that afferent noise, mimicking inputs to the neurons, causes smoothing of the system's response function, displacing equilibria and altering the stability of oscillatory states. Our analysis further shows that these noise-induced changes cause a shift of the peak frequency of synchronous oscillations that scales with input intensity, leading the network towards critical states. We lastly discuss the extension of these principles to periodic stimulation, in which externally applied driving signals can trigger analogous phenomena. Our results reveal one possible mechanism involved in shaping oscillatory activity in the brain and associated control principles.

  2. Dynamic Control of Synchronous Activity in Networks of Spiking Neurons.

    Science.gov (United States)

    Hutt, Axel; Mierau, Andreas; Lefebvre, Jérémie

    Oscillatory brain activity is believed to play a central role in neural coding. Accumulating evidence shows that features of these oscillations are highly dynamic: power, frequency and phase fluctuate alongside changes in behavior and task demands. The role and mechanism supporting this variability is however poorly understood. We here analyze a network of recurrently connected spiking neurons with time delay displaying stable synchronous dynamics. Using mean-field and stability analyses, we investigate the influence of dynamic inputs on the frequency of firing rate oscillations. We show that afferent noise, mimicking inputs to the neurons, causes smoothing of the system's response function, displacing equilibria and altering the stability of oscillatory states. Our analysis further shows that these noise-induced changes cause a shift of the peak frequency of synchronous oscillations that scales with input intensity, leading the network towards critical states. We lastly discuss the extension of these principles to periodic stimulation, in which externally applied driving signals can trigger analogous phenomena. Our results reveal one possible mechanism involved in shaping oscillatory activity in the brain and associated control principles.

  3. Brucella abortus-activated microglia induce neuronal death through primary phagocytosis.

    Science.gov (United States)

    Rodríguez, Ana M; Delpino, M Victoria; Miraglia, M Cruz; Costa Franco, Miriam M; Barrionuevo, Paula; Dennis, Vida A; Oliveira, Sergio C; Giambartolomei, Guillermo H

    2017-07-01

    Inflammation has long been implicated as a contributor to pathogenesis in neurobrucellosis. Many of the associated neurocognitive symptoms of neurobrucellosis may be the result of neuronal dysfunction resulting from the inflammatory response induced by Brucella abortus infection in the central nervous system. In this manuscript, we describe an immune mechanism for inflammatory activation of microglia that leads to neuronal death upon B. abortus infection. B. abortus was unable to infect or harm primary cultures of mouse neurons. However, when neurons were co-cultured with microglia and infected with B. abortus significant neuronal loss occurred. This phenomenon was dependent on TLR2 activation by Brucella lipoproteins. Neuronal death was not due to apoptosis, but it was dependent on the microglial release of nitric oxide (NO). B. abortus infection stimulated microglial proliferation, phagocytic activity and engulfment of neurons. NO secreted by B. abortus-activated microglia induced neuronal exposure of the "eat-me" signal phosphatidylserine (PS). Blocking of PS-binding to protein milk fat globule epidermal growth factor-8 (MFG-E8) or microglial vitronectin receptor-MFG-E8 interaction was sufficient to prevent neuronal loss by inhibiting microglial phagocytosis without affecting their activation. Taken together, our results indicate that B. abortus is not directly toxic to neurons; rather, these cells become distressed and are killed by phagocytosis in the inflammatory surroundings generated by infected microglia. Neuronal loss induced by B. abortus-activated microglia may explain, in part, the neurological deficits observed during neurobrucellosis. © 2017 Wiley Periodicals, Inc.

  4. Human immunodeficiency virus-1 protein Tat induces excitotoxic loss of presynaptic terminals in hippocampal cultures.

    Science.gov (United States)

    Shin, Angela H; Thayer, Stanley A

    2013-05-01

    Human immunodeficiency virus (HIV) infection of the CNS produces dendritic damage that correlates with cognitive decline in patients with HIV-associated neurocognitive disorders (HAND). HIV-induced neurotoxicity results in part from viral proteins shed from infected cells, including the HIV transactivator of transcription (Tat). We previously showed that Tat binds to the low density lipoprotein receptor-related protein (LRP), resulting in overactivation of NMDA receptors, activation of the ubiquitin-proteasome pathway, and subsequent loss of postsynaptic densities. Here, we show that Tat also induces a loss of presynaptic terminals. The number of presynaptic terminals was quantified using confocal imaging of synaptophysin fused to green fluorescent protein (Syn-GFP). Tat-induced loss of presynaptic terminals was secondary to excitatory postsynaptic mechanisms because treatment with an LRP antagonist or an NMDA receptor antagonist inhibited this loss. Treatment with nutlin-3, an E3 ligase inhibitor, prevented Tat-induced loss of presynaptic terminals. These data suggest that Tat-induced loss of presynaptic terminals is a consequence of excitotoxic postsynaptic activity. We previously found that ifenprodil, an NR2B subunit-selective NMDA receptor antagonist, induced recovery of postsynaptic densities. Here we show that Tat-induced loss of presynaptic terminals was reversed by ifenprodil treatment. Thus, Tat-induced loss of presynaptic terminals is reversible, and this recovery can be initiated by inhibiting a subset of postsynaptic NMDA receptors. Understanding the dynamics of synaptic changes in response to HIV infection of the CNS may lead to the design of improved pharmacotherapies for HAND patients. Copyright © 2012 Elsevier Inc. All rights reserved.

  5. Activity patterns of cochlear ganglion neurones in the starling.

    Science.gov (United States)

    Manley, G A; Gleich, O; Leppelsack, H J; Oeckinghaus, H

    1985-09-01

    Spontaneous activity and responses to simple tonal stimuli were studied in cochlear ganglion neurones of the starling. Both regular and irregular spontaneous activity were recorded. Non-auditory cells have their origin in the macula lagenae. Mean spontaneous rate for auditory cells (all irregularly spiking) was 45 spikes s-1. In half the units having characteristic frequencies (CFs) less than 1.5 kHz, time-interval histograms (TIHs) of spontaneous activity showed regularly-spaced peaks or 'preferred' intervals. The spacing of the peak intervals was, on average, 15% greater than the CF-period interval of the respective units. In TIH of lower-frequency cells without preferred intervals, the modal interval was also on average about 15% longer than the CF-period interval. Apparently, the resting oscillation frequency of these cells lies below their CF. Tuning curves (TCs) of neurones to short tone bursts show no systematic asymmetry as in mammals. Below CF 1 kHz, the low-frequency flanks of the TCs are, on average, steeper than the high-frequency flanks. Above CF 1 kHz, the reverse is true. The cochlear ganglion and nerve are tonotopically organized. Low-frequency fibres arise apically in the papilla basilaris and are found near non-auditory (lagenar) fibres. Discharge rates to short tones were monotonically related to sound pressure level. Saturation rates often exceeded 300 spikes s-1. 'On-off' responses and primary suppression of spontaneous activity were observed. A direct comparison of spontaneous activity and tuning-curve symmetry revealed that, apart from quantitative differences, fundamental qualitative differences exist between starling and guinea-pig primary afferents.

  6. Three-dimensional distribution of sensory stimulation-evoked neuronal activity of spinal dorsal horn neurons analyzed by in vivo calcium imaging.

    Directory of Open Access Journals (Sweden)

    Kazuhiko Nishida

    Full Text Available The spinal dorsal horn comprises heterogeneous populations of interneurons and projection neurons, which form neuronal circuits crucial for processing of primary sensory information. Although electrophysiological analyses have uncovered sensory stimulation-evoked neuronal activity of various spinal dorsal horn neurons, monitoring these activities from large ensembles of neurons is needed to obtain a comprehensive view of the spinal dorsal horn circuitry. In the present study, we established in vivo calcium imaging of multiple spinal dorsal horn neurons by using a two-photon microscope and extracted three-dimensional neuronal activity maps of these neurons in response to cutaneous sensory stimulation. For calcium imaging, a fluorescence resonance energy transfer (FRET-based calcium indicator protein, Yellow Cameleon, which is insensitive to motion artifacts of living animals was introduced into spinal dorsal horn neurons by in utero electroporation. In vivo calcium imaging following pinch, brush, and heat stimulation suggests that laminar distribution of sensory stimulation-evoked neuronal activity in the spinal dorsal horn largely corresponds to that of primary afferent inputs. In addition, cutaneous pinch stimulation elicited activities of neurons in the spinal cord at least until 2 spinal segments away from the central projection field of primary sensory neurons responsible for the stimulated skin point. These results provide a clue to understand neuronal processing of sensory information in the spinal dorsal horn.

  7. Three-dimensional distribution of sensory stimulation-evoked neuronal activity of spinal dorsal horn neurons analyzed by in vivo calcium imaging.

    Science.gov (United States)

    Nishida, Kazuhiko; Matsumura, Shinji; Taniguchi, Wataru; Uta, Daisuke; Furue, Hidemasa; Ito, Seiji

    2014-01-01

    The spinal dorsal horn comprises heterogeneous populations of interneurons and projection neurons, which form neuronal circuits crucial for processing of primary sensory information. Although electrophysiological analyses have uncovered sensory stimulation-evoked neuronal activity of various spinal dorsal horn neurons, monitoring these activities from large ensembles of neurons is needed to obtain a comprehensive view of the spinal dorsal horn circuitry. In the present study, we established in vivo calcium imaging of multiple spinal dorsal horn neurons by using a two-photon microscope and extracted three-dimensional neuronal activity maps of these neurons in response to cutaneous sensory stimulation. For calcium imaging, a fluorescence resonance energy transfer (FRET)-based calcium indicator protein, Yellow Cameleon, which is insensitive to motion artifacts of living animals was introduced into spinal dorsal horn neurons by in utero electroporation. In vivo calcium imaging following pinch, brush, and heat stimulation suggests that laminar distribution of sensory stimulation-evoked neuronal activity in the spinal dorsal horn largely corresponds to that of primary afferent inputs. In addition, cutaneous pinch stimulation elicited activities of neurons in the spinal cord at least until 2 spinal segments away from the central projection field of primary sensory neurons responsible for the stimulated skin point. These results provide a clue to understand neuronal processing of sensory information in the spinal dorsal horn.

  8. Activation of D2 dopamine receptor-expressing neurons in the nucleus accumbens increases motivation

    Science.gov (United States)

    Soares-Cunha, Carina; Coimbra, Barbara; David-Pereira, Ana; Borges, Sonia; Pinto, Luisa; Costa, Patricio; Sousa, Nuno; Rodrigues, Ana J.

    2016-01-01

    Striatal dopamine receptor D1-expressing neurons have been classically associated with positive reinforcement and reward, whereas D2 neurons are associated with negative reinforcement and aversion. Here we demonstrate that the pattern of activation of D1 and D2 neurons in the nucleus accumbens (NAc) predicts motivational drive, and that optogenetic activation of either neuronal population enhances motivation in mice. Using a different approach in rats, we further show that activating NAc D2 neurons increases cue-induced motivational drive in control animals and in a model that presents anhedonia and motivational deficits; conversely, optogenetic inhibition of D2 neurons decreases motivation. Our results suggest that the classic view of D1–D2 functional antagonism does not hold true for all dimensions of reward-related behaviours, and that D2 neurons may play a more prominent pro-motivation role than originally anticipated. PMID:27337658

  9. Deficient Rab11 activity underlies glucose hypometabolism in primary neurons of Huntington’s disease mice

    International Nuclear Information System (INIS)

    Li, Xueyi; Valencia, Antonio; McClory, Hollis; Sapp, Ellen; Kegel, Kimberly B.; DiFiglia, Marian

    2012-01-01

    Highlights: ► Primary Huntington’s disease neurons are impaired in taking up glucose. ► Rab11 modulates glucose uptake in neurons. ► Increasing Rab11 activity attenuates the glucose uptake defect in disease neurons. ► We provide a novel mechanism for glucose hypometabolism in Huntington’s disease. -- Abstract: Huntington’s disease (HD) is a progressive neurodegenerative disorder caused by a CAG repeat expansion in the huntingtin gene. Positron emission tomography studies have revealed a decline in glucose metabolism in the brain of patients with HD by a mechanism that has not been established. We examined glucose utilization in embryonic primary cortical neurons of wild-type (WT) and HD knock-in mice, which have 140 CAG repeats inserted in the endogenous mouse huntingtin gene (HD 140Q/140Q ). Primary HD 140Q/140Q cortical neurons took up significantly less glucose than did WT neurons. Expression of permanently inactive and permanently active forms of Rab11 correspondingly altered glucose uptake in WT neurons, suggesting that normal activity of Rab11 is needed for neuronal uptake of glucose. It is known that Rab11 activity is diminished in HD 140Q/140Q neurons. Expression of dominant active Rab11 to enhance the activity of Rab11 normalized glucose uptake in HD 140Q/140Q neurons. These results suggest that deficient activity of Rab11 is a novel mechanism for glucose hypometabolism in HD.

  10. NAA and NAAG variation in neuronal activation during visual stimulation.

    Science.gov (United States)

    Castellano, G; Dias, C S B; Foerster, B; Li, L M; Covolan, R J M

    2012-11-01

    N-acetyl-aspartyl-glutamate (NAAG) and its hydrolysis product N-acetyl-L-aspartate (NAA) are among the most important brain metabolites. NAA is a marker of neuron integrity and viability, while NAAG modulates glutamate release and may have a role in neuroprotection and synaptic plasticity. Investigating on a quantitative basis the role of these metabolites in brain metabolism in vivo by magnetic resonance spectroscopy (MRS) is a major challenge since the main signals of NAA and NAAG largely overlap. This is a preliminary study in which we evaluated NAA and NAAG changes during a visual stimulation experiment using functional MRS. The paradigm used consisted of a rest period (5 min and 20 s), followed by a stimulation period (10 min and 40 s) and another rest period (10 min and 40 s). MRS from 17 healthy subjects were acquired at 3T with TR/TE = 2000/288 ms. Spectra were averaged over subjects and quantified with LCModel. The main outcomes were that NAA concentration decreased by about 20% with the stimulus, while the concentration of NAAG concomitantly increased by about 200%. Such variations fall into models for the energy metabolism underlying neuronal activation that point to NAAG as being responsible for the hyperemic vascular response that causes the BOLD signal. They also agree with the fact that NAAG and NAA are present in the brain at a ratio of about 1:10, and with the fact that the only known metabolic pathway for NAAG synthesis is from NAA and glutamate.

  11. NAA and NAAG variation in neuronal activation during visual stimulation

    International Nuclear Information System (INIS)

    Castellano, G.; Dias, C.S.B.; Foerster, B.; Li, L.M.; Covolan, R.J.M.

    2012-01-01

    N-acetyl-aspartyl-glutamate (NAAG) and its hydrolysis product N-acetyl-aspartate (NAA) are among the most important brain metabolites. NAA is a marker of neuron integrity and viability, while NAAG modulates glutamate release and may have a role in neuroprotection and synaptic plasticity. Investigating on a quantitative basis the role of these metabolites in brain metabolism in vivo by magnetic resonance spectroscopy (MRS) is a major challenge since the main signals of NAA and NAAG largely overlap. This is a preliminary study in which we evaluated NAA and NAAG changes during a visual stimulation experiment using functional MRS. The paradigm used consisted of a rest period (5 min and 20 s), followed by a stimulation period (10 min and 40 s) and another rest period (10 min and 40 s). MRS from 17 healthy subjects were acquired at 3T with TR/TE = 2000/288 ms. Spectra were averaged over subjects and quantified with LCModel. The main outcomes were that NAA concentration decreased by about 20% with the stimulus, while the concentration of NAAG concomitantly increased by about 200%. Such variations fall into models for the energy metabolism underlying neuronal activation that point to NAAG as being responsible for the hyperemic vascular response that causes the BOLD signal. They also agree with the fact that NAAG and NAA are present in the brain at a ratio of about 1:10, and with the fact that the only known metabolic pathway for NAAG synthesis is from NAA and glutamate

  12. NAA and NAAG variation in neuronal activation during visual stimulation

    Energy Technology Data Exchange (ETDEWEB)

    Castellano, G.; Dias, C.S.B. [Grupo de Neurofísica, Departamento de Raios Cósmicos e Cronologia, Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas, Campinas, SP (Brazil); Programa de Cooperação Interinstitucional de Apoio à Pesquisa sobre o Cérebro (CInAPCe), SP (Brazil); Foerster, B. [Philips Medical Systems, São Paulo, SP (Brazil); Programa de Cooperação Interinstitucional de Apoio à Pesquisa sobre o Cérebro (CInAPCe), SP (Brazil); Li, L.M. [Departamento de Neurologia, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, Campinas, SP (Brazil); Programa de Cooperação Interinstitucional de Apoio à Pesquisa sobre o Cérebro (CInAPCe), SP (Brazil); Covolan, R.J.M. [Grupo de Neurofísica, Departamento de Raios Cósmicos e Cronologia, Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas, Campinas, SP (Brazil); Programa de Cooperação Interinstitucional de Apoio à Pesquisa sobre o Cérebro (CInAPCe), SP (Brazil)

    2012-08-17

    N-acetyl-aspartyl-glutamate (NAAG) and its hydrolysis product N-acetyl-aspartate (NAA) are among the most important brain metabolites. NAA is a marker of neuron integrity and viability, while NAAG modulates glutamate release and may have a role in neuroprotection and synaptic plasticity. Investigating on a quantitative basis the role of these metabolites in brain metabolism in vivo by magnetic resonance spectroscopy (MRS) is a major challenge since the main signals of NAA and NAAG largely overlap. This is a preliminary study in which we evaluated NAA and NAAG changes during a visual stimulation experiment using functional MRS. The paradigm used consisted of a rest period (5 min and 20 s), followed by a stimulation period (10 min and 40 s) and another rest period (10 min and 40 s). MRS from 17 healthy subjects were acquired at 3T with TR/TE = 2000/288 ms. Spectra were averaged over subjects and quantified with LCModel. The main outcomes were that NAA concentration decreased by about 20% with the stimulus, while the concentration of NAAG concomitantly increased by about 200%. Such variations fall into models for the energy metabolism underlying neuronal activation that point to NAAG as being responsible for the hyperemic vascular response that causes the BOLD signal. They also agree with the fact that NAAG and NAA are present in the brain at a ratio of about 1:10, and with the fact that the only known metabolic pathway for NAAG synthesis is from NAA and glutamate.

  13. RECOVERY ACT - Thylakoid Assembly and Folded Protein Transport by the Tat Pathway

    Energy Technology Data Exchange (ETDEWEB)

    Dabney-Smith, Carole [Miami Univ., Oxford, OH (United States)

    2016-07-18

    system mechanism in chloroplasts will lead to a better understanding of the biogenesis of photosynthetic membranes potentially providing a means to engineer photosynthetic complexes into synthetic membranes for energy production. We are especially well prepared to undertake this project because we have developed a novel functional replacement assay, which was used to demonstrate a correlation of Tha4 oligomerization to transport. Thylakoids of plant chloroplasts provide a very robust, reliable assay to gain mechanistic detail about cpTat systems, providing most of the biochemical analyses to date. We plan to test our central hypothesis and accomplish the overall objective of this proposal by (1) Identifying the cpTat component(s) that interact with the mature domain of precursor during transport, (2) Determining the organization of the cpTat translocon, and (3) Comparing Tha4 topology in thylakoids during active transport and at rest. The proposed studies are innovative due to our ability to correlate structural changes in cpTat protein complexes during the transport of precursor. At the completion of this project, we expect to know the cpTat component(s) that interacts directly with the mature domain of the precursor, important because it is not known which components comprise the pore for passage of the mature domain. We also expect to know the arrangement of the components in the cpTat transport complex through direct interaction between Tha4 and the other CpTat components, a key point to establishing the mechanism of translocation. Lastly, we expect to correlate topological changes of Tha4 with precursor transport, key to establishing Tha4's role in the transport process. The successful completion of these studies is expected to have an important impact in understanding chloroplast biogenesis and assembly of photosynthetic complexes in plants and photosynthetic bacteria.

  14. Behavioral Modulation by Spontaneous Activity of Dopamine Neurons

    Directory of Open Access Journals (Sweden)

    Toshiharu Ichinose

    2017-12-01

    Full Text Available Dopamine modulates a variety of animal behaviors that range from sleep and learning to courtship and aggression. Besides its well-known phasic firing to natural reward, a substantial number of dopamine neurons (DANs are known to exhibit ongoing intrinsic activity in the absence of an external stimulus. While accumulating evidence points at functional implications for these intrinsic “spontaneous activities” of DANs in cognitive processes, a causal link to behavior and its underlying mechanisms has yet to be elucidated. Recent physiological studies in the model organism Drosophila melanogaster have uncovered that DANs in the fly brain are also spontaneously active, and that this activity reflects the behavioral/internal states of the animal. Strikingly, genetic manipulation of basal DAN activity resulted in behavioral alterations in the fly, providing critical evidence that links spontaneous DAN activity to behavioral states. Furthermore, circuit-level analyses have started to reveal cellular and molecular mechanisms that mediate or regulate spontaneous DAN activity. Through reviewing recent findings in different animals with the major focus on flies, we will discuss potential roles of this physiological phenomenon in directing animal behaviors.

  15. Permanent Genetic Access to Transiently Active Neurons via TRAP: Targeted Recombination in Active Populations

    OpenAIRE

    Guenthner, Casey J.; Miyamichi, Kazunari; Yang, Helen H.; Heller, H. Craig; Luo, Liqun

    2013-01-01

    Targeting genetically encoded tools for neural circuit dissection to relevant cellular populations is a major challenge in neurobiology. We developed a new approach, Targeted Recombination in Active Populations (TRAP), to obtain genetic access to neurons that were activated by defined stimuli. This method utilizes mice in which the tamoxifen-dependent recombinase CreERT2 is expressed in an activity-dependent manner from the loci of the immediate early genes Arc and Fos. Active cells that expr...

  16. An improved ivermectin-activated chloride channel receptor for inhibiting electrical activity in defined neuronal populations

    DEFF Research Database (Denmark)

    Lynagh, Timothy Peter; Lynch, Joseph W

    2010-01-01

    The ability to silence the electrical activity of defined neuronal populations in vivo is dramatically advancing our understanding of brain function. This technology may eventually be useful clinically for treating a variety of neuropathological disorders caused by excessive neuronal activity...... conductance, homomeric expression, and human origin may render the F207A/A288G alpha1 glycine receptor an improved silencing receptor for neuroscientific and clinical purposes. As all known highly ivermectin-sensitive GluClRs contain an endogenous glycine residue at the corresponding location, this residue...

  17. Permanent genetic access to transiently active neurons via TRAP: targeted recombination in active populations.

    Science.gov (United States)

    Guenthner, Casey J; Miyamichi, Kazunari; Yang, Helen H; Heller, H Craig; Luo, Liqun

    2013-06-05

    Targeting genetically encoded tools for neural circuit dissection to relevant cellular populations is a major challenge in neurobiology. We developed an approach, targeted recombination in active populations (TRAP), to obtain genetic access to neurons that were activated by defined stimuli. This method utilizes mice in which the tamoxifen-dependent recombinase CreER(T2) is expressed in an activity-dependent manner from the loci of the immediate early genes Arc and Fos. Active cells that express CreER(T2) can only undergo recombination when tamoxifen is present, allowing genetic access to neurons that are active during a time window of less than 12 hr. We show that TRAP can provide selective access to neurons activated by specific somatosensory, visual, and auditory stimuli and by experience in a novel environment. When combined with tools for labeling, tracing, recording, and manipulating neurons, TRAP offers a powerful approach for understanding how the brain processes information and generates behavior. Copyright © 2013 Elsevier Inc. All rights reserved.

  18. Antibodies to the HIV-1 Tat protein correlated with nonprogression to AIDS: a rationale for the use of Tat toxoid as an HIV-1 vaccine.

    Science.gov (United States)

    Zagury, J F; Sill, A; Blattner, W; Lachgar, A; Le Buanec, H; Richardson, M; Rappaport, J; Hendel, H; Bizzini, B; Gringeri, A; Carcagno, M; Criscuolo, M; Burny, A; Gallo, R C; Zagury, D

    1998-01-01

    To investigate which immune parameters, such as antibodies against HIV-1 specificities, or viral parameters, such as p24 antigenemia, are predictive of disease progression. We performed studies on serum collected from individuals exhibiting two extremes of disease evolution--67 fast progressors (FP) and 182 nonprogressors (NP)--at their enrollment. After a 1- to 2-year clinical follow-up of 104 nonprogressors after their enrollment, we could determine the best serologic predictors for disease progression. We investigated levels of antibodies to tetanus toxoid and to HIV antigens including Env, Gag, Nef, and Tat proteins, as well as p24 antigenemia, viremia, CD4 cell count, and interferon-alpha (IFN-alpha) titers in FPs and NPs, and we correlated these data with clinical and biologic signs of progression. p24 Antigenemia, a marker of viral replication, and anti-Tat antibodies were highly and inversely correlated in both groups (P < .001). Furthermore, anti-p24 antibodies and low serum IFN-alpha levels were correlated to the NP versus the FP cohort. Finally, among NPs, only antibodies to Tat and not to the other HIV specificities (Env, Nef, Gag) were significantly predictive of clinical stability during their follow-up. Antibodies toward HIV-1 Tat, which are inversely correlated to p24 antigenemia, appear as a critical marker for a lack of disease progression. This study strongly suggests that rising anti-Tat antibodies through active immunization may be beneficial in AIDS vaccine development to control viral replication.

  19. Network feedback regulates motor output across a range of modulatory neuron activity.

    Science.gov (United States)

    Spencer, Robert M; Blitz, Dawn M

    2016-06-01

    Modulatory projection neurons alter network neuron synaptic and intrinsic properties to elicit multiple different outputs. Sensory and other inputs elicit a range of modulatory neuron activity that is further shaped by network feedback, yet little is known regarding how the impact of network feedback on modulatory neurons regulates network output across a physiological range of modulatory neuron activity. Identified network neurons, a fully described connectome, and a well-characterized, identified modulatory projection neuron enabled us to address this issue in the crab (Cancer borealis) stomatogastric nervous system. The modulatory neuron modulatory commissural neuron 1 (MCN1) activates and modulates two networks that generate rhythms via different cellular mechanisms and at distinct frequencies. MCN1 is activated at rates of 5-35 Hz in vivo and in vitro. Additionally, network feedback elicits MCN1 activity time-locked to motor activity. We asked how network activation, rhythm speed, and neuron activity levels are regulated by the presence or absence of network feedback across a physiological range of MCN1 activity rates. There were both similarities and differences in responses of the two networks to MCN1 activity. Many parameters in both networks were sensitive to network feedback effects on MCN1 activity. However, for most parameters, MCN1 activity rate did not determine the extent to which network output was altered by the addition of network feedback. These data demonstrate that the influence of network feedback on modulatory neuron activity is an important determinant of network output and feedback can be effective in shaping network output regardless of the extent of network modulation. Copyright © 2016 the American Physiological Society.

  20. The Tat protein of human immunodeficiency virus-1 enhances hepatitis C virus replication through interferon gamma-inducible protein-10

    Directory of Open Access Journals (Sweden)

    Qu Jing

    2012-04-01

    Full Text Available Abstract Background Co-infection with human immunodeficiency virus-1 (HIV-1 and hepatitis C virus (HCV is associated with faster progression of liver disease and an increase in HCV persistence. However, the mechanism by which HIV-1 accelerates the progression of HCV liver disease remains unknown. Results HIV-1/HCV co-infection is associated with increased expression of interferon gamma-induced protein-10 (IP-10 mRNA in peripheral blood mononuclear cells (PBMCs. HCV RNA levels were higher in PBMCs of patients with HIV-1/HCV co-infection than in patients with HCV mono-infection. HIV-1 Tat and IP-10 activated HCV replication in a time-dependent manner, and HIV-1 Tat induced IP-10 production. In addition, the effect of HIV-1 Tat on HCV replication was blocked by anti-IP-10 monoclonal antibody, demonstrating that the effect of HIV-1 Tat on HCV replication depends on IP-10. Taken together, these results suggest that HIV-1 Tat protein activates HCV replication by upregulating IP-10 production. Conclusions HIV-1/HCV co-infection is associated with increased expression of IP-10 mRNA and replication of HCV RNA. Furthermore, both HIV-1 Tat and IP-10 activate HCV replication. HIV-1 Tat activates HCV replication by upregulating IP-10 production. These results expand our understanding of HIV-1 in HCV replication and the mechanism involved in the regulation of HCV replication mediated by HIV-1 during co-infection.

  1. Curtailing effect of awakening on visual responses of cortical neurons by cholinergic activation of inhibitory circuits.

    Science.gov (United States)

    Kimura, Rui; Safari, Mir-Shahram; Mirnajafi-Zadeh, Javad; Kimura, Rie; Ebina, Teppei; Yanagawa, Yuchio; Sohya, Kazuhiro; Tsumoto, Tadaharu

    2014-07-23

    Visual responsiveness of cortical neurons changes depending on the brain state. Neural circuit mechanism underlying this change is unclear. By applying the method of in vivo two-photon functional calcium imaging to transgenic rats in which GABAergic neurons express fluorescent protein, we analyzed changes in visual response properties of cortical neurons when animals became awakened from anesthesia. In the awake state, the magnitude and reliability of visual responses of GABAergic neurons increased whereas the decay of responses of excitatory neurons became faster. To test whether the basal forebrain (BF) cholinergic projection is involved in these changes, we analyzed effects of electrical and optogenetic activation of BF on visual responses of mouse cortical neurons with in vivo imaging and whole-cell recordings. Electrical BF stimulation in anesthetized animals induced the same direction of changes in visual responses of both groups of neurons as awakening. Optogenetic activation increased the frequency of visually evoked action potentials in GABAergic neurons but induced the delayed hyperpolarization that ceased the late generation of action potentials in excitatory neurons. Pharmacological analysis in slice preparations revealed that photoactivation-induced depolarization of layer 1 GABAergic neurons was blocked by a nicotinic receptor antagonist, whereas non-fast-spiking layer 2/3 GABAergic neurons was blocked only by the application of both nicotinic and muscarinic receptor antagonists. These results suggest that the effect of awakening is mediated mainly through nicotinic activation of layer 1 GABAergic neurons and mixed nicotinic/muscarinic activation of layer 2/3 non-fast-spiking GABAergic neurons, which together curtails the visual responses of excitatory neurons. Copyright © 2014 the authors 0270-6474/14/3410122-12$15.00/0.

  2. Synaptic network activity induces neuronal differentiation of adult hippocampal precursor cells through BDNF signaling

    Directory of Open Access Journals (Sweden)

    Harish Babu

    2009-09-01

    Full Text Available Adult hippocampal neurogenesis is regulated by activity. But how do neural precursor cells in the hippocampus respond to surrounding network activity and translate increased neural activity into a developmental program? Here we show that long-term potential (LTP-like synaptic activity within a cellular network of mature hippocampal neurons promotes neuronal differentiation of newly generated cells. In co-cultures of precursor cells with primary hippocampal neurons, LTP-like synaptic plasticity induced by addition of glycine in Mg2+-free media for 5 min, produced synchronous network activity and subsequently increased synaptic strength between neurons. Furthermore, this synchronous network activity led to a significant increase in neuronal differentiation from the co-cultured neural precursor cells. When applied directly to precursor cells, glycine and Mg2+-free solution did not induce neuronal differentiation. Synaptic plasticity-induced neuronal differentiation of precursor cells was observed in the presence of GABAergic neurotransmission blockers but was dependent on NMDA-mediated Ca2+ influx. Most importantly, neuronal differentiation required the release of brain-derived neurotrophic factor (BDNF from the underlying substrate hippocampal neurons as well as TrkB receptor phosphorylation in precursor cells. This suggests that activity-dependent stem cell differentiation within the hippocampal network is mediated via synaptically evoked BDNF signaling.

  3. Fast and direct detection of neuronal activation with diffusion MRI

    Energy Technology Data Exchange (ETDEWEB)

    Le Bihan, D. [Service Hospitalier Frederic Joliot (CEA/DSV/DRM), Lab. Anatomical and Functional Neuroimaging, 91 - Orsay (France); Urayama, S.; Aso, T.; Hanakawa, T.; Fukuyama, H. [Kyoto Univ. Graduate School of Medicine, Human Brain Research Center, Kyoto (Japan)

    2006-07-01

    Over the last 30 years functional neuroimaging has emerged as a revolutionary path to study the brain and the mind. This has been possible because of significant advances mainly in two imaging modalities, namely Positron Emission Tomograph y (PET) and Magnetic Resonance Imaging (MRI). Amazingly, although those two modalities are based on radically different physical approaches (detection of 1 3 radioactivity for the first one and nuclear magnetization for the second), both allo w brain activation images to be obtained through measurements involving water molecules. So far, PET and MRI functional imaging have relied on the same principle that neuronal activation and blood flow are coupled through metabolism: Blood flow increases locally in activated brain regions. In the case of PET one uses H{sub 2}O radioactive water which is produced by using a cyclotron and injected to the subject vasculature. In activated brain regions the increase in blood flow leads to a local increase in the tissue radioactive water content detected and localized by the PE T camera. With MRI the hydrogen nuclei of brain endogenous water molecules are magnetized by a strong external magnetic field. In activated regions the increase in blood flow results in an increase of blood oxygenation which induces a slight perturbation of the magnetization relaxation properties of the water molecules around blood vessels detected by the MRI scanner (so called 'BOLD' effect). I n both approaches water is, thus, merely an indirect means to look at changes in cerebral blood flow which accompany brain activation, and although PET and BOLD f MRI have been extremely successful for the functional neuroimaging community, present well known limitations. While the coupling between neuronal activation, metabolism and blood flow has been verified in most instances including BOLD f MRI, the degree and the mechanism of coupling remains largely debated (Magistratt, Pellerin, Mangia) and may fail in some

  4. Activation of afferent renal nerves modulates RVLM-projecting PVN neurons.

    Science.gov (United States)

    Xu, Bo; Zheng, Hong; Liu, Xuefei; Patel, Kaushik P

    2015-05-01

    Renal denervation for the treatment of hypertension has proven to be successful; however, the underlying mechanism/s are not entirely clear. To determine if preautonomic neurons in the paraventricular nucleus (PVN) respond to afferent renal nerve (ARN) stimulation, extracellular single-unit recording was used to investigate the contribution of the rostral ventrolateral medulla (RVLM)-projecting PVN (PVN-RVLM) neurons to the response elicited during stimulation of ARN. In 109 spontaneously active neurons recorded in the PVN of anesthetized rats, 25 units were antidromically activated from the RVLM. Among these PVN-RVLM neurons, 84% (21/25) were activated by ARN stimulation. The baseline discharge rate was significantly higher in these neurons than those PVN-RVLM neurons not activated by ARN stimulation (16%, 4/25). The responsiveness of these neurons to baroreflex activation induced by phenylephrine and activation of cardiac sympathetic afferent reflex (CSAR) was also examined. Almost all of the PVN neurons that responded to ARN stimulation were sensitive to baroreflex (95%) and CSAR (100%). The discharge characteristics for nonevoked neurons (not activated by RVLM antidromic stimulation) showed that 23% of these PVN neurons responded to ARN stimulation. All the PVN neurons that responded to ARN stimulation were activated by N-methyl-D-aspartate, and these responses were attenuated by the glutamate receptor blocker AP5. These experiments demonstrated that sensory information originating in the kidney is integrated at the level of preautonomic neurons within the PVN, providing a novel mechanistic insight for use of renal denervation in the modulation of sympathetic outflow in disease states such as hypertension and heart failure. Copyright © 2015 the American Physiological Society.

  5. Activation of groups of excitatory neurons in the mammalian spinal cord or hindbrain evokes locomotion

    DEFF Research Database (Denmark)

    Hägglund, Martin; Borgius, Lotta; Dougherty, Kimberly J.

    2010-01-01

    Central pattern generators (CPGs) are spinal neuronal networks required for locomotion. Glutamatergic neurons have been implicated as being important for intrinsic rhythm generation in the CPG and for the command signal for initiating locomotion, although this has not been demonstrated directly. We...... neurons in the spinal cord are critical for initiating or maintaining the rhythm and that activation of hindbrain areas containing the locomotor command regions is sufficient to directly activate the spinal locomotor network....

  6. Brain Innate Immunity Regulates Hypothalamic Arcuate Neuronal Activity and Feeding Behavior

    NARCIS (Netherlands)

    Reis, Wagner L.; Yi, Chun-Xia; Gao, Yuanqing; Tschöp, Mathias H.; Stern, Javier E.

    2015-01-01

    Hypothalamic inflammation, involving microglia activation in the arcuate nucleus (ARC), is proposed as a novel underlying mechanism in obesity, insulin and leptin resistance. However, whether activated microglia affects ARC neuronal activity, and consequently basal and hormonal-induced food intake,

  7. TAT improves in vitro transportation of fortilin through midgut and into hemocytes of white shrimp Litopenaeus vannamei

    Science.gov (United States)

    Zhou, Yi; Zhang, Wenbing; Mai, Kangsen; Xu, Wei; Zhang, Yanjiao; Ai, Qinghui; Wang, Xiaojie

    2012-06-01

    Fortilin is a multifunctional protein implicated in many important cellular processes. Since injection of Pm-fortilin reduces shrimp mortality caused by white spot syndrome virus (WSSV), there is potential application of fortilin in shrimp culture. In the present study, in order to improve trans-membrane transportation efficiency, the protein transduction domain of the transactivator of transcription (TAT) peptide was fused to fortilin. The Pichia pastoris yeast expression system, which is widely accepted in animal feeds, was used for production of recombinant fusion protein. Green fluorescence protein (GFP) was selected as a reporter because of its intrinsic visible fluorescence. The fortilin, TAT and GFP fusion protein were constructed. Their trans-membrane transportation efficiency and effects on immune response of shrimp were analyzed in vitro. Results showed that TAT peptide improved in vitro uptake of fortilin into the hemocytes and midgut of Litopenaeus vannamei. The phenoloxidase (PO) activity of hemocytes incubated with GFP-Fortilin or GFP-Fortilin-TAT was significantly increased compared with that in the control without expressed fortilin. The PO activity of hemocytes incubated with 200 μg mL-1 GFP-Fortilin-TAT was significantly higher than that in the group with the same concentration of GFP-Fortilin. Hemocytes incubated with GFP-Fortilin-TAT at all concentrations showed significantly higher nitric oxide synthase (NOS) activity than those in the control or in the GFP-Fortilin treatment. The present in vitro study indicated that TAT fusion protein improved the immune effect of fortilin.

  8. Crosstalk between HDAC6 and Nox2-based NADPH oxidase mediates HIV-1 Tat-induced pro-inflammatory responses in astrocytes

    Directory of Open Access Journals (Sweden)

    Gi Soo Youn

    2017-08-01

    Full Text Available Histone deacetylase 6 (HDAC6 likely is important in inflammatory diseases. However, how HDAC6 exerts its effect on inflammatory processes remains unclear. HIV-1 transactivator of transcription (Tat activates NADPH oxidase resulting in generation of reactive oxygen species (ROS, leading to extensive neuro-inflammation in the central nervous system. We investigated the correlation of HDAC6 and NADPH oxidase in HIV-1 Tat-stimulated astrocytes. HDAC6 knockdown attenuated HIV-1 Tat-induced ROS generation and NADPH oxidase activation. HDAC6 knockdown suppressed HIV-1 Tat-induced expression of NADPH oxidase subunits, such as Nox2, p47phox, and p22phox. Specific inhibition of HDAC6 using tubastatin A suppressed HIV-1 Tat-induced ROS generation and activation of NADPH oxidase. N-acetyl cysteine, diphenyl iodonium, and apocynin suppressed HIV-1 Tat-induced expression of HDAC6 and the pro-inflammatory chemokines CCL2, CXCL8, and CXCL10. Nox2 knockdown attenuated HIV-1 Tat-induced HDAC6 expression and subsequent expression of chemokines. The collective results point to the potential crosstalk between HDAC6 and NADPH oxidase, which could be a combined therapeutic target for relief of HIV-1 Tat-mediated neuro-inflammation. Keywords: HIV-1 Tat, HDAC6, NADPH oxidase, ROS, Inflammation, Astrocytes

  9. Apolipoprotein A-IV inhibits AgRP/NPY neurons and activates POMC neurons in the arcuate nucleus

    Science.gov (United States)

    Apolipoprotein A-IV (apoA-IV) in the brain potently suppresses food intake. However the mechanisms underlying its anorexigenic effects remain to be identified. We first examined the effects of apoA-IV on cellular activities in hypothalamic neurons that co-express agouti-related peptide (AgRP) and ne...

  10. NAA and NAAG variation in neuronal activation during visual stimulation

    Directory of Open Access Journals (Sweden)

    G. Castellano

    2012-11-01

    Full Text Available N-acetyl-aspartyl-glutamate (NAAG and its hydrolysis product N-acetyl-L-aspartate (NAA are among the most important brain metabolites. NAA is a marker of neuron integrity and viability, while NAAG modulates glutamate release and may have a role in neuroprotection and synaptic plasticity. Investigating on a quantitative basis the role of these metabolites in brain metabolism in vivo by magnetic resonance spectroscopy (MRS is a major challenge since the main signals of NAA and NAAG largely overlap. This is a preliminary study in which we evaluated NAA and NAAG changes during a visual stimulation experiment using functional MRS. The paradigm used consisted of a rest period (5 min and 20 s, followed by a stimulation period (10 min and 40 s and another rest period (10 min and 40 s. MRS from 17 healthy subjects were acquired at 3T with TR/TE = 2000/288 ms. Spectra were averaged over subjects and quantified with LCModel. The main outcomes were that NAA concentration decreased by about 20% with the stimulus, while the concentration of NAAG concomitantly increased by about 200%. Such variations fall into models for the energy metabolism underlying neuronal activation that point to NAAG as being responsible for the hyperemic vascular response that causes the BOLD signal. They also agree with the fact that NAAG and NAA are present in the brain at a ratio of about 1:10, and with the fact that the only known metabolic pathway for NAAG synthesis is from NAA and glutamate.

  11. Effects of VPAC1 activation in nucleus ambiguus neurons.

    Science.gov (United States)

    Gherghina, Florin Liviu; Tica, Andrei Adrian; Deliu, Elena; Abood, Mary E; Brailoiu, G Cristina; Brailoiu, Eugen

    2017-02-15

    The pituitary adenylyl cyclase-activating polypeptide (PACAP) and its G protein-coupled receptors, PAC1, VPAC1 and VPAC2 form a system involved in a variety of biological processes. Although some sympathetic stimulatory effects of this system have been reported, its central cardiovascular regulatory properties are poorly characterized. VPAC1 receptors are expressed in the nucleus ambiguus (nAmb), a key center controlling cardiac parasympathetic tone. In this study, we report that selective VPAC1 activation in rhodamine-labeled cardiac vagal preganglionic neurons of the rat nAmb produces inositol 1,4,5-trisphosphate receptor-mediated Ca 2+ mobilization, membrane depolarization and activation of P/Q-type Ca 2+ channels. In vivo, this pathway converges onto transient reduction in heart rate of conscious rats. Therefore we demonstrate a VPAC1-dependent mechanism in the central parasympathetic regulation of the heart rate, adding to the complexity of PACAP-mediated cardiovascular modulation. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Neurons have an active glycogen metabolism that contributes to tolerance to hypoxia

    Science.gov (United States)

    Saez, Isabel; Duran, Jordi; Sinadinos, Christopher; Beltran, Antoni; Yanes, Oscar; Tevy, María F; Martínez-Pons, Carlos; Milán, Marco; Guinovart, Joan J

    2014-01-01

    Glycogen is present in the brain, where it has been found mainly in glial cells but not in neurons. Therefore, all physiologic roles of brain glycogen have been attributed exclusively to astrocytic glycogen. Working with primary cultured neurons, as well as with genetically modified mice and flies, here we report that—against general belief—neurons contain a low but measurable amount of glycogen. Moreover, we also show that these cells express the brain isoform of glycogen phosphorylase, allowing glycogen to be fully metabolized. Most importantly, we show an active neuronal glycogen metabolism that protects cultured neurons from hypoxia-induced death and flies from hypoxia-induced stupor. Our findings change the current view of the role of glycogen in the brain and reveal that endogenous neuronal glycogen metabolism participates in the neuronal tolerance to hypoxic stress. PMID:24569689

  13. Neurons have an active glycogen metabolism that contributes to tolerance to hypoxia.

    Science.gov (United States)

    Saez, Isabel; Duran, Jordi; Sinadinos, Christopher; Beltran, Antoni; Yanes, Oscar; Tevy, María F; Martínez-Pons, Carlos; Milán, Marco; Guinovart, Joan J

    2014-06-01

    Glycogen is present in the brain, where it has been found mainly in glial cells but not in neurons. Therefore, all physiologic roles of brain glycogen have been attributed exclusively to astrocytic glycogen. Working with primary cultured neurons, as well as with genetically modified mice and flies, here we report that-against general belief-neurons contain a low but measurable amount of glycogen. Moreover, we also show that these cells express the brain isoform of glycogen phosphorylase, allowing glycogen to be fully metabolized. Most importantly, we show an active neuronal glycogen metabolism that protects cultured neurons from hypoxia-induced death and flies from hypoxia-induced stupor. Our findings change the current view of the role of glycogen in the brain and reveal that endogenous neuronal glycogen metabolism participates in the neuronal tolerance to hypoxic stress.

  14. Enhanced activation of RVLM-projecting PVN neurons in rats with chronic heart failure.

    Science.gov (United States)

    Xu, Bo; Zheng, Hong; Patel, Kaushik P

    2012-04-15

    Previous studies have indicated that there is increased activation of the paraventricular nucleus (PVN) in rats with chronic heart failure (CHF); however, it is not clear if the preautonomic neurons within the PVN are specifically overactive. Also, it is not known if these neurons have altered responses to baroreceptor or osmotic challenges. Experiments were conducted in rats with CHF (6-8 wk after coronary artery ligation). Spontaneously active neurons were recorded in the PVN, of which 36% were antidromically activated from the rostral ventrolateral medulla (RVLM). The baseline discharge rate in RVLM-projecting PVN (PVN-RVLM) neurons from CHF rats was significantly greater than in sham-operated (sham) rats (6.0 ± 0.6 vs. 2.6 ± 0.3 spikes/s, P neurons by 80% in CHF rats compared with 37% in sham rats. Fifty-two percent of spontaneously active PVN-RVLM neurons responded to changes in the mean arterial pressure (MAP). The changes in discharge rate in PVN-RVLM neurons after a reduction in MAP (+52 ± 7% vs. +184 ± 61%) or an increase in MAP (-42 ± 8% vs. -71 ± 6%) were significantly attenuated in rats with CHF compared with sham rats. Most PVN-RVLM neurons (63%), including all barosensitive PVN-RVLM neurons, were excited by an internal carotid artery injection of hypertonic NaCl (2.1 osmol/l), whereas a smaller number (7%) were inhibited. The increase in discharge rate in PVN-RVLM neurons to hypertonic stimulation was significantly enhanced in rats with CHF compared with sham rats (134 ± 15% vs. 92 ± 13%). Taken together, these data suggest that PVN-RVLM neurons are more active under basal conditions and this overactivation is mediated by an enhanced glutamatergic tone in rats with CHF. Furthermore, this enhanced activation of PVN-RVLM neurons may contribute to the altered responses to baroreceptor and osmotic challenges observed during CHF.

  15. Cross-interval histogram analysis of neuronal activity on multi-electrode arrays

    NARCIS (Netherlands)

    Castellone, P.; Rutten, Wim; Marani, Enrico

    2003-01-01

    Cross-neuron-interval histogram (CNIH) analysis has been performed in order to study correlated activity and connectivity between pairs of neurons in a spontaneously active developing cultured network of rat cortical cells. Thirty-eight histograms could be analyzed using two parameters, one for the

  16. Oral glucose intake inhibits hypothalamic neuronal activity more effectively than glucose infusion

    NARCIS (Netherlands)

    Smeets, P.A.M.; Vidarsdottir, S.; Graaf, de C.; Stafleu, A.; Osch, M.J.P.; Viergever, M.A.; Pijl, H.; Grond, van der J.

    2007-01-01

    Oral glucose intake inhibits hypothalamic neuronal activity more effectively than glucose infusion. Am J Physiol Endocrinol Metab 293: E754-E758, 2007. First published June 12, 2007; doi:10.1152/ajpendo.00231.2007. - We previously showed that hypothalamic neuronal activity, as measured by the blood

  17. Oral glucose intake inhibits hypothalamic neuronal activity more effectively than glucose infusion

    NARCIS (Netherlands)

    Smeets, P.A.M.; Vidarsdottir, S.; Graaf, C. de; Stafleu, A.; Osch, M.J.P. van; Viergever, M.A.; Pijl, H.; Grond, J. van der

    2007-01-01

    We previously showed that hypothalamic neuronal activity, as measured by the blood oxygen level-dependent (BOLD) functional MRI signal, declines in response to oral glucose intake. To further explore the mechanism driving changes in hypothalamic neuronal activity in response to an oral glucose load,

  18. From Structure to Activity: Using Centrality Measures to Predict Neuronal Activity.

    Science.gov (United States)

    Fletcher, Jack McKay; Wennekers, Thomas

    2018-03-01

    It is clear that the topological structure of a neural network somehow determines the activity of the neurons within it. In the present work, we ask to what extent it is possible to examine the structural features of a network and learn something about its activity? Specifically, we consider how the centrality (the importance of a node in a network) of a neuron correlates with its firing rate. To investigate, we apply an array of centrality measures, including In-Degree, Closeness, Betweenness, Eigenvector, Katz, PageRank, Hyperlink-Induced Topic Search (HITS) and NeuronRank to Leaky-Integrate and Fire neural networks with different connectivity schemes. We find that Katz centrality is the best predictor of firing rate given the network structure, with almost perfect correlation in all cases studied, which include purely excitatory and excitatory-inhibitory networks, with either homogeneous connections or a small-world structure. We identify the properties of a network which will cause this correlation to hold. We argue that the reason Katz centrality correlates so highly with neuronal activity compared to other centrality measures is because it nicely captures disinhibition in neural networks. In addition, we argue that these theoretical findings are applicable to neuroscientists who apply centrality measures to functional brain networks, as well as offer a neurophysiological justification to high level cognitive models which use certain centrality measures.

  19. Induction of associative olfactory memory by targeted activation of single olfactory neurons in Drosophila larvae.

    Science.gov (United States)

    Honda, Takato; Lee, Chi-Yu; Yoshida-Kasikawa, Maki; Honjo, Ken; Furukubo-Tokunaga, Katsuo

    2014-04-25

    It has been postulated that associative memory is formed by at least two sets of external stimuli, CS and US, that are transmitted to the memory centers by distinctive conversing pathways. However, whether associative memory can be induced by the activation of only the olfactory CS and a biogenic amine-mediated US pathways remains to be elucidated. In this study, we substituted the reward signals with dTrpA1-mediated thermogenetic activation of octopaminergic neurons and the odor signals by ChR2-mediated optical activation of a specific class of olfactory neurons. We show that targeted activation of the olfactory receptor and the octopaminergic neurons is indeed sufficient for the formation of associative olfactory memory in the larval brain. We also show that targeted stimulation of only a single type of olfactory receptor neurons is sufficient to induce olfactory memory that is indistinguishable from natural memory induced by the activation of multiple olfactory receptor neurons.

  20. Celastrol ameliorates HIV-1 Tat-induced inflammatory responses via NF-kappaB and AP-1 inhibition and heme oxygenase-1 induction in astrocytes

    International Nuclear Information System (INIS)

    Youn, Gi Soo; Kwon, Dong-Joo; Ju, Sung Mi; Rhim, Hyangshuk; Bae, Yong Soo; Choi, Soo Young; Park, Jinseu

    2014-01-01

    HIV-1 Tat causes extensive neuroinflammation that may progress to AIDS-related encephalitis and dementia. Celastrol possesses various biological activities such as anti-oxidant, anti-tumor, and anti-inflammatory activities. In this study, we investigated the modulatory effects of celastrol on HIV-1 Tat-induced inflammatory responses and the molecular mechanisms underlying its action in astrocytes. Pre-treatment of CRT-MG human astroglioma cells with celastrol significantly inhibited HIV-1 Tat-induced expression of ICAM-1/VCAM-1 and subsequent monocyte adhesiveness in CRT-MG cells. In addition, celastrol suppressed HIV-1 Tat-induced expression of pro-inflammatory chemokines, such as CXCL10, IL-8, and MCP-1. Celastrol decreased HIV-1 Tat-induced activation of JNK MAPK, AP-1, and NF-κB. Furthermore, celastrol induced mRNA and protein expression of HO-1 as well as Nrf2 activation. Blockage of HO-1 expression using siRNA reversed the inhibitory effect of celastrol on HIV-1 Tat-induced inflammatory responses. These results suggest that celastrol has regulatory effects on HIV-1 Tat-induced inflammatory responses by blocking the JNK MAPK-AP-1/NF-κB signaling pathways and inducing HO-1 expression in astrocytes. - Highlights: • Celastrol suppressed HIV-1 Tat-induced expression of pro-inflammatory genes. • Celastrol inhibited HIV-1 Tat -induced activation of JNK MAPK. • Celastrol inhibited HIV-1 Tat-induced activation of both NF-κB and AP-1. • Celastrol inhibited HIV-1 Tat-induced inflammatory responses via HO-1 induction

  1. Celastrol ameliorates HIV-1 Tat-induced inflammatory responses via NF-kappaB and AP-1 inhibition and heme oxygenase-1 induction in astrocytes

    Energy Technology Data Exchange (ETDEWEB)

    Youn, Gi Soo; Kwon, Dong-Joo; Ju, Sung Mi [Department of Biomedical Science and Research Institute for Bioscience and Biotechnology, Hallym University, Chunchon 200-702 (Korea, Republic of); Rhim, Hyangshuk [Department of Biomedical Sciences, Department of Medical Life Sciences, College of Medicine, the Catholic University of Korea, Seoul 137-701 (Korea, Republic of); Bae, Yong Soo [Department of Biological Science, College of Natural Sciences, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Choi, Soo Young [Department of Biomedical Science and Research Institute for Bioscience and Biotechnology, Hallym University, Chunchon 200-702 (Korea, Republic of); Park, Jinseu, E-mail: jinpark@hallym.ac.kr [Department of Biomedical Science and Research Institute for Bioscience and Biotechnology, Hallym University, Chunchon 200-702 (Korea, Republic of)

    2014-10-01

    HIV-1 Tat causes extensive neuroinflammation that may progress to AIDS-related encephalitis and dementia. Celastrol possesses various biological activities such as anti-oxidant, anti-tumor, and anti-inflammatory activities. In this study, we investigated the modulatory effects of celastrol on HIV-1 Tat-induced inflammatory responses and the molecular mechanisms underlying its action in astrocytes. Pre-treatment of CRT-MG human astroglioma cells with celastrol significantly inhibited HIV-1 Tat-induced expression of ICAM-1/VCAM-1 and subsequent monocyte adhesiveness in CRT-MG cells. In addition, celastrol suppressed HIV-1 Tat-induced expression of pro-inflammatory chemokines, such as CXCL10, IL-8, and MCP-1. Celastrol decreased HIV-1 Tat-induced activation of JNK MAPK, AP-1, and NF-κB. Furthermore, celastrol induced mRNA and protein expression of HO-1 as well as Nrf2 activation. Blockage of HO-1 expression using siRNA reversed the inhibitory effect of celastrol on HIV-1 Tat-induced inflammatory responses. These results suggest that celastrol has regulatory effects on HIV-1 Tat-induced inflammatory responses by blocking the JNK MAPK-AP-1/NF-κB signaling pathways and inducing HO-1 expression in astrocytes. - Highlights: • Celastrol suppressed HIV-1 Tat-induced expression of pro-inflammatory genes. • Celastrol inhibited HIV-1 Tat -induced activation of JNK MAPK. • Celastrol inhibited HIV-1 Tat-induced activation of both NF-κB and AP-1. • Celastrol inhibited HIV-1 Tat-induced inflammatory responses via HO-1 induction.

  2. États financiers 2015–2016

    International Development Research Centre (IDRC) Digital Library (Canada)

    une assurance raisonnable qu'il pourra réaliser ses objectifs. .... les employés et leur procure des services de santé avant ...... indépendance, à un audit des états financiers annuels, conformément aux normes d'audit généralement reconnues.

  3. Circadian Activators Are Expressed Days before They Initiate Clock Function in Late Pacemaker Neurons from Drosophila.

    Science.gov (United States)

    Liu, Tianxin; Mahesh, Guruswamy; Houl, Jerry H; Hardin, Paul E

    2015-06-03

    Circadian pacemaker neurons in the Drosophila brain control daily rhythms in locomotor activity. These pacemaker neurons can be subdivided into early or late groups depending on whether rhythms in period (per) and timeless (tim) expression are initiated at the first instar (L1) larval stage or during metamorphosis, respectively. Because CLOCK-CYCLE (CLK-CYC) heterodimers initiate circadian oscillator function by activating per and tim transcription, a Clk-GFP transgene was used to mark when late pacemaker neurons begin to develop. We were surprised to see that CLK-GFP was already expressed in four of five clusters of late pacemaker neurons during the third instar (L3) larval stage. CLK-GFP is only detected in postmitotic neurons from L3 larvae, suggesting that these four late pacemaker neuron clusters are formed before the L3 larval stage. A GFP-cyc transgene was used to show that CYC, like CLK, is also expressed exclusively in pacemaker neurons from L3 larval brains, demonstrating that CLK-CYC is not sufficient to activate per and tim in late pacemaker neurons at the L3 larval stage. These results suggest that most late pacemaker neurons develop days before novel factors activate circadian oscillator function during metamorphosis. Copyright © 2015 the authors 0270-6474/15/358662-10$15.00/0.

  4. A Tat-conjugated Peptide Nucleic Acid Tat-PNA-DR Inhibits Hepatitis B Virus Replication In Vitro and In Vivo by Targeting LTR Direct Repeats of HBV RNA

    Science.gov (United States)

    Zeng, Zhengyang; Han, Shisong; Hong, Wei; Lang, Yange; Li, Fangfang; Liu, Yongxiang; Li, Zeyong; Wu, Yingliang; Li, Wenxin; Zhang, Xianzheng; Cao, Zhijian

    2016-01-01

    Hepatitis B virus (HBV) infection is a major cause of chronic active hepatitis, cirrhosis, and primary hepatocellular carcinoma, all of which are severe threats to human health. However, current clinical therapies for HBV are limited by potential side effects, toxicity, and drug-resistance. In this study, a cell-penetrating peptide-conjugated peptide nucleic acid (PNA), Tat-PNA-DR, was designed to target the direct repeat (DR) sequences of HBV. Tat-PNA-DR effectively inhibited HBV replication in HepG2.2.15 cells. Its anti-HBV effect relied on the binding of Tat-PNA-DR to the DR, whereby it suppressed the translation of hepatitis B e antigen (HBeAg), HBsAg, HBV core, hepatitis B virus x protein, and HBV reverse transcriptase (RT) and the reverse transcription of the HBV genome. Furthermore, Tat-PNA-DR administered by intravenous injection efficiently cleared HBeAg and HBsAg in an acute hepatitis B mouse model. Importantly, it induced an 80% decline in HBV DNA in mouse serum, which was similar to the effect of the widely used clinical drug Lamivudine (3TC). Additionally, a long-term hydrodynamics HBV mouse model also demonstrated Tat-PNA-DR's antiviral effect. Interestingly, Tat-PNA-DR displayed low cytotoxicity, low mouse acute toxicity, low immunogenicity, and high serum stability. These data indicate that Tat-PNA-DR is a unique PNA and a promising drug candidate against HBV. PMID:26978579

  5. A Tat-conjugated Peptide Nucleic Acid Tat-PNA-DR Inhibits Hepatitis B Virus Replication In Vitro and In Vivo by Targeting LTR Direct Repeats of HBV RNA

    Directory of Open Access Journals (Sweden)

    Zhengyang Zeng

    2016-01-01

    Full Text Available Hepatitis B virus (HBV infection is a major cause of chronic active hepatitis, cirrhosis, and primary hepatocellular carcinoma, all of which are severe threats to human health. However, current clinical therapies for HBV are limited by potential side effects, toxicity, and drug-resistance. In this study, a cell-penetrating peptide-conjugated peptide nucleic acid (PNA, Tat-PNA-DR, was designed to target the direct repeat (DR sequences of HBV. Tat-PNA-DR effectively inhibited HBV replication in HepG2.2.15 cells. Its anti-HBV effect relied on the binding of Tat-PNA-DR to the DR, whereby it suppressed the translation of hepatitis B e antigen (HBeAg, HBsAg, HBV core, hepatitis B virus x protein, and HBV reverse transcriptase (RT and the reverse transcription of the HBV genome. Furthermore, Tat-PNA-DR administered by intravenous injection efficiently cleared HBeAg and HBsAg in an acute hepatitis B mouse model. Importantly, it induced an 80% decline in HBV DNA in mouse serum, which was similar to the effect of the widely used clinical drug Lamivudine (3TC. Additionally, a long-term hydrodynamics HBV mouse model also demonstrated Tat-PNA-DR's antiviral effect. Interestingly, Tat-PNA-DR displayed low cytotoxicity, low mouse acute toxicity, low immunogenicity, and high serum stability. These data indicate that Tat-PNA-DR is a unique PNA and a promising drug candidate against HBV.

  6. Activity-dependent neurorehabilitation beyond physical trainings: "mental exercise" through mirror neuron activation

    OpenAIRE

    Yuan, Ti-Fei; Chen, Wei; Shan, Chunlei; Rocha, Nuno; Arias-Carrión, Oscar; Paes, Flávia; de Sa, Alberto Souza; Machado, Sergio

    2015-01-01

    The activity dependent brain repair mechanism has been widely adopted in many types of neurorehabilitation. The activity leads to target specific and non-specific beneficial effects in different brain regions, such as the releasing of neurotrophic factors, modulation of the cytokines and generation of new neurons in adult hood. However physical exercise program clinically are limited to some of the patients with preserved motor functions; while many patients suffered from paralysis cannot mak...

  7. Neuronal activity in the hub of extrasynaptic Schwann cell-axon interactions

    Directory of Open Access Journals (Sweden)

    Chrysanthi eSamara

    2013-11-01

    Full Text Available The integrity and function of neurons depend on their continuous interactions with glial cells. In the peripheral nervous system glial functions are exerted by Schwann cells (SCs. SCs sense synaptic and extrasynaptic manifestations of action potential propagation and adapt their physiology to support neuronal activity. We review here existing literature data on extrasynaptic bidirectional axon-SC communication, focusing particularly on neuronal activity implications. To shed light on underlying mechanisms, we conduct a thorough analysis of microarray data from SC-rich mouse sciatic nerve at different developmental stages and in neuropathic models. We identify molecules that are potentially involved in SC detection of neuronal activity signals inducing subsequent glial responses. We further suggest that alterations in the activity-dependent axon-SC crosstalk impact on peripheral neuropathies. Together with previously reported data, these observations open new perspectives for deciphering glial mechanisms of neuronal function support.

  8. BDNF heightens the sensitivity of motor neurons to excitotoxic insults through activation of TrkB

    Science.gov (United States)

    Hu, Peter; Kalb, Robert G.; Walton, K. D. (Principal Investigator)

    2003-01-01

    The survival promoting and neuroprotective actions of brain-derived neurotrophic factor (BDNF) are well known but under certain circumstances this growth factor can also exacerbate excitotoxic insults to neurons. Prior exploration of the receptor through which BDNF exerts this action on motor neurons deflects attention away from p75. Here we investigated the possibility that BDNF acts through the receptor tyrosine kinase, TrkB, to confer on motor neurons sensitivity to excitotoxic challenge. We blocked BDNF activation of TrkB using a dominant negative TrkB mutant or a TrkB function blocking antibody, and found that this protected motor neurons against excitotoxic insult in cultures of mixed spinal cord neurons. Addition of a function blocking antibody to BDNF to mixed spinal cord neuron cultures is also neuroprotective indicating that endogenously produced BDNF participates in vulnerability to excitotoxicity. We next examined the intracellular signaling cascades that are engaged upon TrkB activation. Previously we found that inhibition of the phosphatidylinositide-3'-kinase (PI3'K) pathway blocks BDNF-induced excitotoxic sensitivity. Here we show that expression of a constitutively active catalytic subunit of PI3'K, p110, confers excitotoxic sensitivity (ES) upon motor neurons not incubated with BDNF. Parallel studies with purified motor neurons confirm that these events are likely to be occuring specifically within motor neurons. The abrogation of BDNF's capacity to accentuate excitotoxic insults may make it a more attractive neuroprotective agent.

  9. Changes in prefrontal neuronal activity after learning to perform a spatial working memory task.

    Science.gov (United States)

    Qi, Xue-Lian; Meyer, Travis; Stanford, Terrence R; Constantinidis, Christos

    2011-12-01

    The prefrontal cortex is considered essential for learning to perform cognitive tasks though little is known about how the representation of stimulus properties is altered by learning. To address this issue, we recorded neuronal activity in monkeys before and after training on a task that required visual working memory. After the subjects learned to perform the task, we observed activation of more prefrontal neurons and increased activity during working memory maintenance. The working memory-related increase in firing rate was due mostly to regular-spiking putative pyramidal neurons. Unexpectedly, the selectivity of neurons for stimulus properties and the ability of neurons to discriminate between stimuli decreased as the information about stimulus properties was apparently present in neural firing prior to training and neuronal selectivity degraded after training in the task. The effect was robust and could not be accounted for by differences in sampling sites, selection of neurons, level of performance, or merely the elapse of time. The results indicate that, in contrast to the effects of perceptual learning, mastery of a cognitive task degrades the apparent stimulus selectivity as neurons represent more abstract information related to the task. This effect is countered by the recruitment of more neurons after training.

  10. Glutamate transporter activity promotes enhanced Na+/K+-ATPase -mediated extracellular K+ management during neuronal activity

    DEFF Research Database (Denmark)

    Larsen, Brian R; Holm, Rikke; Vilsen, Bente

    2016-01-01

    , in addition, Na+ /K+ -ATPase-mediated K+ clearance could be governed by astrocytic [Na+ ]i . During most neuronal activity, glutamate is released in the synaptic cleft and is re-absorbed by astrocytic Na+ -coupled glutamate transporters, thereby elevating [Na+ ]i . It thus remains unresolved whether...... the different Na+ /K+ -ATPase isoforms are controlled by [K+ ]o or [Na+ ]i during neuronal activity. Hippocampal slice recordings of stimulus-induced [K+ ]o transients with ion-sensitive microelectrodes revealed reduced Na+ /K+ -ATPase-mediated K+ management upon parallel inhibition of the glutamate transporter......+ affinity to the α1 and α2 isoforms than the β2 isoform. In summary, enhanced astrocytic Na+ /K+ -ATPase-dependent K+ clearance was obtained with parallel glutamate transport activity. The astrocytic Na+ /K+ -ATPase isoform constellation α2β1 appeared to be specifically geared to respond to the [Na+ ]i...

  11. Predictive features of persistent activity emergence in regular spiking and intrinsic bursting model neurons.

    Directory of Open Access Journals (Sweden)

    Kyriaki Sidiropoulou

    Full Text Available Proper functioning of working memory involves the expression of stimulus-selective persistent activity in pyramidal neurons of the prefrontal cortex (PFC, which refers to neural activity that persists for seconds beyond the end of the stimulus. The mechanisms which PFC pyramidal neurons use to discriminate between preferred vs. neutral inputs at the cellular level are largely unknown. Moreover, the presence of pyramidal cell subtypes with different firing patterns, such as regular spiking and intrinsic bursting, raises the question as to what their distinct role might be in persistent firing in the PFC. Here, we use a compartmental modeling approach to search for discriminatory features in the properties of incoming stimuli to a PFC pyramidal neuron and/or its response that signal which of these stimuli will result in persistent activity emergence. Furthermore, we use our modeling approach to study cell-type specific differences in persistent activity properties, via implementing a regular spiking (RS and an intrinsic bursting (IB model neuron. We identify synaptic location within the basal dendrites as a feature of stimulus selectivity. Specifically, persistent activity-inducing stimuli consist of activated synapses that are located more distally from the soma compared to non-inducing stimuli, in both model cells. In addition, the action potential (AP latency and the first few inter-spike-intervals of the neuronal response can be used to reliably detect inducing vs. non-inducing inputs, suggesting a potential mechanism by which downstream neurons can rapidly decode the upcoming emergence of persistent activity. While the two model neurons did not differ in the coding features of persistent activity emergence, the properties of persistent activity, such as the firing pattern and the duration of temporally-restricted persistent activity were distinct. Collectively, our results pinpoint to specific features of the neuronal response to a given

  12. Activation of the Basal Forebrain by the Orexin/Hypocretin Neurons: Orexin International Symposium

    Science.gov (United States)

    Arrigoni, Elda; Mochizuki, Takatoshi; Scammell, Thomas E.

    2010-01-01

    The orexin neurons play an essential role in driving arousal and in maintaining normal wakefulness. Lack of orexin neurotransmission produces a chronic state of hypoarousal characterized by excessive sleepiness, frequent transitions between wake and sleep, and episodes of cataplexy. A growing body of research now suggests that the basal forebrain (BF) may be a key site through which the orexin-producing neurons promote arousal. Here we review anatomical, pharmacological and electrophysiological studies on how the orexin neurons may promote arousal by exciting cortically-projecting neurons of the BF. Orexin fibers synapse on BF cholinergic neurons and orexin-A is released in the BF during waking. Local application of orexins excites BF cholinergic neurons, induces cortical release of acetylcholine, and promotes wakefulness. The orexin neurons also contain and probably co-release the inhibitory neuropeptide dynorphin. We found that orexin-A and dynorphin have specific effects on different classes of BF neurons that project to the cortex. Cholinergic neurons were directly excited by orexin-A, but did not respond to dynorphin. Non-cholinergic BF neurons that project to the cortex seem to comprise at least two populations with some directly excited by orexin that may represent wake-active, GABAergic neurons, whereas others did not respond to orexin but were inhibited by dynorphin and may be sleep-active, GABAergic neurons. This evidence suggests that the BF is a key site through which orexins activate the cortex and promotes behavioral arousal. In addition, orexins and dynorphin may act synergistically in the BF to promote arousal and improve cognitive performance. PMID:19723027

  13. Mediodorsal Thalamic Neurons Mirror the Activity of Medial Prefrontal Neurons Responding to Movement and Reinforcement during a Dynamic DNMTP Task.

    Science.gov (United States)

    Miller, Rikki L A; Francoeur, Miranda J; Gibson, Brett M; Mair, Robert G

    2017-01-01

    The mediodorsal nucleus (MD) interacts with medial prefrontal cortex (mPFC) to support learning and adaptive decision-making. MD receives driver (layer 5) and modulatory (layer 6) projections from PFC and is the main source of driver thalamic projections to middle cortical layers of PFC. Little is known about the activity of MD neurons and their influence on PFC during decision-making. We recorded MD neurons in rats performing a dynamic delayed nonmatching to position (dDNMTP) task and compared results to a previous study of mPFC with the same task (Onos et al., 2016). Criterion event-related responses were observed for 22% (254/1179) of neurons recorded in MD, 237 (93%) of which exhibited activity consistent with mPFC response types. More MD than mPFC neurons exhibited responses related to movement (45% vs. 29%) and reinforcement (51% vs. 27%). MD had few responses related to lever presses, and none related to preparation or memory delay, which constituted 43% of event-related activity in mPFC. Comparison of averaged normalized population activity and population response times confirmed the broad similarity of common response types in MD and mPFC and revealed differences in the onset and offset of some response types. Our results show that MD represents information about actions and outcomes essential for decision-making during dDNMTP, consistent with evidence from lesion studies that MD supports reward-based learning and action-selection. These findings support the hypothesis that MD reinforces task-relevant neural activity in PFC that gives rise to adaptive behavior.

  14. Naphthazarin protects against glutamate-induced neuronal death via activation of the Nrf2/ARE pathway

    Energy Technology Data Exchange (ETDEWEB)

    Son, Tae Gen; Kawamoto, Elisa M.; Yu, Qian-Sheng; Greig, Nigel H. [Laboratory of Neurosciences, National Institute on Aging, Intramural Research Program, 251 Bayview Blvd., Baltimore, MD 21224 (United States); Mattson, Mark P. [Laboratory of Neurosciences, National Institute on Aging, Intramural Research Program, 251 Bayview Blvd., Baltimore, MD 21224 (United States); Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD (United States); Camandola, Simonetta, E-mail: camandolasi@mail.nih.gov [Laboratory of Neurosciences, National Institute on Aging, Intramural Research Program, 251 Bayview Blvd., Baltimore, MD 21224 (United States)

    2013-04-19

    Highlights: •Naphthazarin activates the Nrf2/ARE pathway. •Naphthazarin induces Nrf2-driven genes in neurons and astrocytes. •Naphthazarin protects neurons against excitotoxicity. -- Abstract: Nuclear factor E2-related factor 2 (Nrf2)/antioxidant response element (ARE) pathway is an important cellular stress response pathway involved in neuroprotection. We previously screened several natural phytochemicals and identified plumbagin as a novel activator of the Nrf2/ARE pathway that can protect neurons against ischemic injury. Here we extended our studies to natural and synthetic derivatives of plumbagin. We found that 5,8-dimethoxy-1,4-naphthoquinone (naphthazarin) is a potent activator of the Nrf2/ARE pathway, up-regulates the expression of Nrf2-driven genes in primary neuronal and glial cultures, and protects neurons against glutamate-induced excitotoxicity.

  15. Naphthazarin protects against glutamate-induced neuronal death via activation of the Nrf2/ARE pathway

    International Nuclear Information System (INIS)

    Son, Tae Gen; Kawamoto, Elisa M.; Yu, Qian-Sheng; Greig, Nigel H.; Mattson, Mark P.; Camandola, Simonetta

    2013-01-01

    Highlights: •Naphthazarin activates the Nrf2/ARE pathway. •Naphthazarin induces Nrf2-driven genes in neurons and astrocytes. •Naphthazarin protects neurons against excitotoxicity. -- Abstract: Nuclear factor E2-related factor 2 (Nrf2)/antioxidant response element (ARE) pathway is an important cellular stress response pathway involved in neuroprotection. We previously screened several natural phytochemicals and identified plumbagin as a novel activator of the Nrf2/ARE pathway that can protect neurons against ischemic injury. Here we extended our studies to natural and synthetic derivatives of plumbagin. We found that 5,8-dimethoxy-1,4-naphthoquinone (naphthazarin) is a potent activator of the Nrf2/ARE pathway, up-regulates the expression of Nrf2-driven genes in primary neuronal and glial cultures, and protects neurons against glutamate-induced excitotoxicity

  16. Activity-based anorexia activates CRF immunoreactive neurons in female rats.

    Science.gov (United States)

    Scharner, Sophie; Friedrich, Tiemo; Goebel-Stengel, Miriam; Kobelt, Peter; Rose, Matthias; Stengel, Andreas

    2018-05-01

    Activity-based anorexia (ABA) is a well-established animal model mimicking the eating disorder anorexia nervosa (AN). Since the pathophysiology of AN is yet poorly understood and specific drug treatments are lacking so far, animal models might be useful to further understand this disease. ABA consists of time-restricted access to food for 1.5 h/day and the possibility to exercise in a running wheel for 24 h/day. This combination leads to robust body weight loss as observed in AN. Here, we investigated the activation of brain corticotropin-releasing factor (CRF) neurons, a transmitter involved in the response to stress, emotional processes and also food intake. After development of ABA, rat brains were processed for c-Fos and CRF double immunohistochemistry. ABA increased the number of c-Fos/CRF double labeled neurons in the paraventricular nucleus (PVN) and the dorsomedial hypothalamic nucleus (DMH) compared to the ad libitum (AL, ad libitum fed, no running wheel) and activity (AC, ad libitum fed, running wheel, p  0.05) group. Also the number of CRF neurons was increased in the DMH of ABA rats compared to AL and AC (p  0.05). Taken together, brain CRF activated under conditions of ABA might play a role in the development and maintenance of this animal model and possibly also in human AN. Copyright © 2018 Elsevier B.V. All rights reserved.

  17. CALHM1 deficiency impairs cerebral neuron activity and memory flexibility in mice.

    Science.gov (United States)

    Vingtdeux, Valérie; Chang, Eric H; Frattini, Stephen A; Zhao, Haitian; Chandakkar, Pallavi; Adrien, Leslie; Strohl, Joshua J; Gibson, Elizabeth L; Ohmoto, Makoto; Matsumoto, Ichiro; Huerta, Patricio T; Marambaud, Philippe

    2016-04-12

    CALHM1 is a cell surface calcium channel expressed in cerebral neurons. CALHM1 function in the brain remains unknown, but recent results showed that neuronal CALHM1 controls intracellular calcium signaling and cell excitability, two mechanisms required for synaptic function. Here, we describe the generation of Calhm1 knockout (Calhm1(-/-)) mice and investigate CALHM1 role in neuronal and cognitive functions. Structural analysis revealed that Calhm1(-/-) brains had normal regional and cellular architecture, and showed no evidence of neuronal or synaptic loss, indicating that CALHM1 deficiency does not affect brain development or brain integrity in adulthood. However, Calhm1(-/-) mice showed a severe impairment in memory flexibility, assessed in the Morris water maze, and a significant disruption of long-term potentiation without alteration of long-term depression, measured in ex vivo hippocampal slices. Importantly, in primary neurons and hippocampal slices, CALHM1 activation facilitated the phosphorylation of NMDA and AMPA receptors by protein kinase A. Furthermore, neuronal CALHM1 activation potentiated the effect of glutamate on the expression of c-Fos and C/EBPβ, two immediate-early gene markers of neuronal activity. Thus, CALHM1 controls synaptic activity in cerebral neurons and is required for the flexible processing of memory in mice. These results shed light on CALHM1 physiology in the mammalian brain.

  18. Context Fear Learning Specifically Activates Distinct Populations of Neurons in Amygdala and Hypothalamus

    Science.gov (United States)

    Trogrlic, Lidia; Wilson, Yvette M.; Newman, Andrew G.; Murphy, Mark

    2011-01-01

    The identity and distribution of neurons that are involved in any learning or memory event is not known. In previous studies, we identified a discrete population of neurons in the lateral amygdala that show learning-specific activation of a c-"fos"-regulated transgene following context fear conditioning. Here, we have extended these studies to…

  19. A lightweight telemetry system for recording neuronal activity in freely behaving small animals

    NARCIS (Netherlands)

    Schregardus, D.S.; Pieneman, A.W.; ter Maat, A.; Brouwer, T.J.F.; Gahr, M.L.

    2006-01-01

    A miniature lightweight radio telemetric device is described which is shown to be suitable for recording neuronal activity in freely behaving animals. Its size (12 × 5 × 8 mm) and weight (1.0-1.1 g with batteries, 0.4-0.5 g without) make the device particularly suitable for recording neuronal units

  20. Acute activation of GLP-1-expressing neurons promotes glucose homeostasis and insulin sensitivity

    Directory of Open Access Journals (Sweden)

    Xuemei Shi

    2017-11-01

    Conclusions: We conclude that acute activation of PPG neurons in the brainstem reduces basal glucose production, enhances intraperitoneal glucose tolerance, and augments hepatic insulin sensitivity, suggesting an important physiological role of PPG neurons-mediated circuitry in promoting glycemic control and insulin sensitivity.

  1. Does rapid and physiological astrocyte–neuron signalling amplify epileptic activity?

    Science.gov (United States)

    2016-01-01

    Abstract The hippocampus is a key brain region in the pathophysiology of mesial temporal lobe epilepsy. Long‐term changes of its architecture and function on the network and cellular level are well documented in epilepsy. Astrocytes can control many aspects of neuronal function and their long‐term alterations over weeks, months and years play an important role in epilepsy. However, a pathophysiological transformation of astrocytes does not seem to be required for astrocytes to contribute to epileptic activity. Some of the properties of physiological astrocyte–neuron communication could allow these cells to exacerbate or synchronize neuronal firing on shorter time scales of milliseconds to minutes. Therefore, these astrocyte–neuron interactions are increasingly recognized as potential contributors to epileptic activity. Fast and reciprocal communication between astrocytes and neurons is enabled by a diverse set of mechanisms that could both amplify and counteract epileptic activity. They may thus promote or cause development of epileptic activity or inhibit it. Mechanisms of astrocyte–neuron interactions that can quickly increase network excitability involve, for example, astrocyte Ca2+ and Na+ signalling, K+ buffering, gap junction coupling and metabolism. However, rapid changes of astrocyte neurotransmitter uptake and morphology may also underlie or support development of network hyperexcitability. The temporal characteristics of these interactions, their ability to synchronize neuronal activity and their net effect on network activity will determine their contribution to the emergence or maintenance of epileptic activity. PMID:27106234

  2. Does rapid and physiological astrocyte-neuron signalling amplify epileptic activity?

    Science.gov (United States)

    Henneberger, Christian

    2017-03-15

    The hippocampus is a key brain region in the pathophysiology of mesial temporal lobe epilepsy. Long-term changes of its architecture and function on the network and cellular level are well documented in epilepsy. Astrocytes can control many aspects of neuronal function and their long-term alterations over weeks, months and years play an important role in epilepsy. However, a pathophysiological transformation of astrocytes does not seem to be required for astrocytes to contribute to epileptic activity. Some of the properties of physiological astrocyte-neuron communication could allow these cells to exacerbate or synchronize neuronal firing on shorter time scales of milliseconds to minutes. Therefore, these astrocyte-neuron interactions are increasingly recognized as potential contributors to epileptic activity. Fast and reciprocal communication between astrocytes and neurons is enabled by a diverse set of mechanisms that could both amplify and counteract epileptic activity. They may thus promote or cause development of epileptic activity or inhibit it. Mechanisms of astrocyte-neuron interactions that can quickly increase network excitability involve, for example, astrocyte Ca 2+ and Na + signalling, K + buffering, gap junction coupling and metabolism. However, rapid changes of astrocyte neurotransmitter uptake and morphology may also underlie or support development of network hyperexcitability. The temporal characteristics of these interactions, their ability to synchronize neuronal activity and their net effect on network activity will determine their contribution to the emergence or maintenance of epileptic activity. © 2016 The Authors. The Journal of Physiology © 2016 The Physiological Society.

  3. On the role of the second coding exon of the HIV-1 Tat protein in virus replication and MHC class I downregulation

    NARCIS (Netherlands)

    Verhoef, K.; Bauer, M.; Meyerhans, A.; Berkhout, B.

    1998-01-01

    Tat is an essential protein of human immunodeficiency virus type 1 (HIV-1) and activates transcription from the viral long terminal repeat (LTR) promoter. The tat gene is composed of two coding exons of which the first, corresponding to the N-terminal 72 amino acid residues, has been reported to be

  4. Nutritive, Post-ingestive Signals Are the Primary Regulators of AgRP Neuron Activity

    Directory of Open Access Journals (Sweden)

    Zhenwei Su

    2017-12-01

    Full Text Available Summary: The brain regulates food intake by processing sensory cues and peripheral physiological signals, but the neural basis of this integration remains unclear. Hypothalamic, agouti-related protein (AgRP-expressing neurons are critical regulators of food intake. AgRP neuron activity is high during hunger and is rapidly reduced by the sight and smell of food. Here, we reveal two distinct components of AgRP neuron activity regulation: a rapid but transient sensory-driven signal and a slower, sustained calorie-dependent signal. We discovered that nutrients are necessary and sufficient for sustained reductions in AgRP neuron activity and that activity reductions are proportional to the calories obtained. This change in activity is recapitulated by exogenous administration of gut-derived satiation signals. Furthermore, we showed that the nutritive value of food trains sensory systems—in a single trial—to drive rapid, anticipatory AgRP neuron activity inhibition. Together, these data demonstrate that nutrients are the primary regulators of AgRP neuron activity. : Su et al. demonstrate that nutrient content in the GI tract is rapidly signaled to hypothalamic neurons activated by hunger. This rapid effect is mediated by three satiation signals that synergistically reduce the activity of AgRP neurons. These findings uncover how hunger circuits in the brain are regulated and raise the possibility that hunger can be pharmacologically controlled. Keywords: calcium imaging, AgRP neurons, calories, satiation signals, sensory regulation, single trial learning, cholecystokinin, CCK, peptide tyrosine tyrosine, PYY, amylin, homeostasis

  5. Inhibiting cholesterol degradation induces neuronal sclerosis and epileptic activity in mouse hippocampus

    Science.gov (United States)

    Chali, Farah; Djelti, Fathia; Eugene, Emmanuel; Valderrama, Mario; Marquer, Catherine; Aubourg, Patrick; Duykaerts, Charles; Miles, Richard; Cartier, Nathalie; Navarro, Vincent

    2015-01-01

    Elevations in neuronal cholesterol have been associated with several degenerative diseases. An enhanced excitability and synchronous firing in surviving neurons are among the sequels of neuronal death in these diseases and also in some epileptic syndromes. Here, we attempted to increase neuronal cholesterol levels, using a short hairpin RNA (shRNA) to suppress expression of the enzyme CYP46A1. This protein hydroxylates cholesterol and so facilitates trans-membrane extrusion. A sh-RNA CYP46A1construction coupled to an adeno-associated virus (AAV5) was injected focally and unilaterally into mouse hippocampus. It was selectively expressed first in neurons of the CA3a region. Cytoplasmic and membrane cholesterol increased, neuronal soma volume increased and then decreased before pyramidal cells died. As CA3a pyramidal cells died, inter-ictal EEG events occurred during exploration and non-REM sleep. With time, neuronal death spread to involve pyramidal cells and interneurons of the CA1 region. CA1 neuronal death was correlated with a delayed local expression of phosphorylated tau. Astrocytes were activated throughout the hippocampus and microglial activation was specific to regions of neuronal death. CA1 neuronal death was correlated with distinct aberrant EEG activity. During exploratory behaviour and rapid eye movement sleep, EEG oscillations at 7-10 Hz (theta) could accelerate to 14-21 Hz (beta) waves. They were accompanied by low amplitude, high-frequency oscillations of peak power at ~300Hz and a range of 250-350 Hz. While episodes of EEG acceleration were not correlated with changes in exploratory behaviour, they were followed in some animals by structured seizure-like discharges. These data strengthen links between increased cholesterol, neuronal sclerosis and epileptic behavior PMID:25847620

  6. Rhythmic activity of feline dorsal and ventral spinocerebellar tract neurons during fictive motor actions

    DEFF Research Database (Denmark)

    Fedirchuk, Brent; Stecina, Katinka; Kristensen, Kasper Kyhl

    2013-01-01

    (without phasic afferent feedback). In this study, we compared the activity of DSCT and VSCT neurons during fictive rhythmic motor behaviors. We used decerebrate cat preparations in which fictive motor tasks can be evoked while the animal is paralyzed and there is no rhythmic sensory input from hindlimb......Neurons of the dorsal spinocerebellar tracts (DSCT) have been described to be rhythmically active during walking on a treadmill in decerebrate cats, but this activity ceased following deafferentation of the hindlimb. This observation supported the hypothesis that DSCT neurons primarily relay...

  7. HIV-1 Tat depresses DNA-PKCS expression and DNA repair, and sensitizes cells to ionizing radiation

    International Nuclear Information System (INIS)

    Sun Yi; Huang Yuechen; Xu Qinzhi; Wang Huiping; Bai Bei; Sui Jianli; Zhou Pingkun

    2006-01-01

    Purpose There is accumulating evidence that cancer patients with human immmunodeficiency virus-1/acquired immunodeficency syndrome (HIV-1/AIDS) have more severe tissue reactions and often develop cutaneous toxic effects when subjected to radiotherapy. Here we explored the effects of the HIV-1 Tat protein on cellular responses to ionizing radiation. Methods and Materials Two Tat-expressing cell lines, TT2 and TE671-Tat, were derived from human rhabdomyosarcoma cells by transfecting with the HIV-1 tat gene. Radiosensitivity was determined using colony-forming ability. Gene expression was assessed by cDNA microarray and immunohybridization. The Comet assay and γ-H2AX foci were use to detect DNA double-strand breaks (DSBs) and repair. Radiation-induced cell cycle changes were detected by flow cytometry. Results The radiosensitivity of TT2 and TE671-Tat cells was significantly increased as compared with parental TE671 cells or the control TE671-pCI cells. Tat also increased proliferation activity. The comet assay and γH2AX foci detection revealed a decreased capacity to repair radiation-induced DNA DSBs in Tat-expressing cells. Microarray assay demonstrated that the DNA repair gene DNA-PKcs, and cell cycle-related genes Cdc20, Cdc25C, KIF2C and CTS1 were downregulated in Tat-expressing cells. Depression of DNA-PKcs in Tat-expressing cells was further confirmed by RT-PCR and immuno-hybridization analysis. Tat-expressing cells exhibited a prolonged S phase arrest after 4 Gy γ-irradiation, and a noticeable delay in the initiation and elimination of radiation-induced G 2 /M arrest as compared with parental cells. In addition, the G 2 /M arrest was incomplete in TT2 cells. Moreover, HIV-1 Tat resulted in a constitutive overexpression of cyclin B1 protein. Conclusion HIV-1 Tat protein sensitizes cells to ionizing radiation via depressing DNA repair and dysregulating cell cycle checkpoints. These observations provide new insight into the increased tissue reactions of AIDS

  8. Sex differences in feeding behavior in rats: the relationship with neuronal activation in the hypothalamus

    Directory of Open Access Journals (Sweden)

    Atsushi eFukushima

    2015-03-01

    Full Text Available There is general agreement that the central nervous system in rodents differs between sexes due to the presence of gonadal steroid hormone during differentiation. Sex differences in feeding seem to occur among species, and responses to fasting (i.e., starvation, gonadal steroids (i.e., testosterone and estradiol, and diet (i.e., western-style diet vary significantly between sexes. The hypothalamus is the center for controlling feeding behavior. We examined the activation of feeding-related peptides in neurons in the hypothalamus. Phosphorylation of cyclic AMP response element-binding protein (CREB is a good marker for neural activation, as is the Fos antigen. Therefore, we predicted that sex differences in the activity of melanin-concentrating hormone (MCH neurons would be associated with feeding behavior. We determined the response of MCH neurons to glucose in the lateral hypothalamic area (LHA and our results suggested MCH neurons play an important role in sex differences in feeding behavior. In addition, fasting increased the number of orexin neurons harboring phosphorylated CREB in female rats (regardless of the estrous day, but not male rats. Glucose injection decreased the number of these neurons with phosphorylated CREB in fasted female rats. Finally, under normal spontaneous food intake, MCH neurons, but not orexin neurons, expressed phosphorylated CREB. These sex differences in response to fasting and glucose, as well as under normal conditions, suggest a vulnerability to metabolic challenges in females.

  9. The Itch-Producing Agents Histamine and Cowhage Activate Separate Populations of Primate Spinothalamic Tract Neurons

    Science.gov (United States)

    Davidson, Steve; Zhang, Xijing; Yoon, Chul H.; Khasabov, Sergey G.; Simone, Donald A.; Giesler, Glenn J.

    2010-01-01

    Itch is an everyday sensation, but when associated with disease or infection it can be chronic and debilitating. Several forms of itch can be blocked using antihistamines, but others cannot and these constitute an important clinical problem. Little information is available on the mechanisms underlying itch that is produced by nonhistaminergic mechanisms. We examined the responses of spinothalamic tract neurons to histaminergic and, for the first time, nonhistaminergic forms of itch stimuli. Fifty-seven primate spinothalamic tract (STT) neurons were identified using antidromic activation techniques and examined for their responses to histamine and cowhage, the nonhistaminergic itch-producing spicules covering the pod of the legume Mucuna pruriens. Each examined neuron had a receptive field on the hairy skin of the hindlimb and responded to noxious mechanical stimulation. STT neurons were tested with both pruritogens applied in a random order and we found 12 that responded to histamine and seven to cowhage. Each pruritogen-responsive STT neuron was activated by the chemical algogen capsaicin and two-thirds responded to noxious heat stimuli, demonstrating that these neurons convey chemical, thermal, and mechanical nociceptive information as well. Histamine or cowhage responsive STT neurons were found in both the marginal zone and the deep dorsal horn and were classified as high threshold and wide dynamic range. Unexpectedly, histamine and cowhage never activated the same cell. Our results demonstrate that the spinothalamic tract contains mutually exclusive populations of neurons responsive to histamine or the nonhistaminergic itch-producing agent cowhage. PMID:17855615

  10. Enhancement of synchronized activity between hippocampal CA1 neurons during initial storage of associative fear memory.

    Science.gov (United States)

    Liu, Yu-Zhang; Wang, Yao; Shen, Weida; Wang, Zhiru

    2017-08-01

    Learning and memory storage requires neuronal plasticity induced in the hippocampus and other related brain areas, and this process is thought to rely on synchronized activity in neural networks. We used paired whole-cell recording in vivo to examine the synchronized activity that was induced in hippocampal CA1 neurons by associative fear learning. We found that both membrane potential synchronization and spike synchronization of CA1 neurons could be transiently enhanced after task learning, as observed on day 1 but not day 5. On day 1 after learning, CA1 neurons showed a decrease in firing threshold and rise times of suprathreshold membrane potential changes as well as an increase in spontaneous firing rates, possibly contributing to the enhancement of spike synchronization. The transient enhancement of CA1 neuronal synchronization may play important roles in the induction of neuronal plasticity for initial storage and consolidation of associative memory. The hippocampus is critical for memory acquisition and consolidation. This function requires activity- and experience-induced neuronal plasticity. It is known that neuronal plasticity is largely dependent on synchronized activity. As has been well characterized, repetitive correlated activity of presynaptic and postsynaptic neurons can lead to long-term modifications at their synapses. Studies on network activity have also suggested that memory processing in the hippocampus may involve learning-induced changes of neuronal synchronization, as observed in vivo between hippocampal CA3 and CA1 networks as well as between the rhinal cortex and the hippocampus. However, further investigation of learning-induced synchronized activity in the hippocampus is needed for a full understanding of hippocampal memory processing. In this study, by performing paired whole-cell recording in vivo on CA1 pyramidal cells (PCs) in anaesthetized adult rats, we examined CA1 neuronal synchronization before and after associative fear

  11. Structural basis for TatA oligomerization: an NMR study of Escherichia coli TatA dimeric structure.

    Directory of Open Access Journals (Sweden)

    Yi Zhang

    Full Text Available Many proteins are transported across lipid membranes by protein translocation systems in living cells. The twin-arginine transport (Tat system identified in bacteria and plant chloroplasts is a unique system that transports proteins across membranes in their fully-folded states. Up to date, the detailed molecular mechanism of this process remains largely unclear. The Escherichia coli Tat system consists of three essential transmembrane proteins: TatA, TatB and TatC. Among them, TatB and TatC form a tight complex and function in substrate recognition. The major component TatA contains a single transmembrane helix followed by an amphipathic helix, and is suggested to form the translocation pore via self-oligomerization. Since the TatA oligomer has to accommodate substrate proteins of various sizes and shapes, the process of its assembly stands essential for understanding the translocation mechanism. A structure model of TatA oligomer was recently proposed based on NMR and EPR observations, revealing contacts between the transmembrane helices from adjacent subunits. Herein we report the construction and stabilization of a dimeric TatA, as well as the structure determination by solution NMR spectroscopy. In addition to more extensive inter-subunit contacts between the transmembrane helices, we were also able to observe interactions between neighbouring amphipathic helices. The side-by-side packing of the amphipathic helices extends the solvent-exposed hydrophilic surface of the protein, which might be favourable for interactions with substrate proteins. The dimeric TatA structure offers more detailed information of TatA oligomeric interface and provides new insights on Tat translocation mechanism.

  12. The pairwise phase consistency in cortical network and its relationship with neuronal activation

    Directory of Open Access Journals (Sweden)

    Wang Daming

    2017-01-01

    Full Text Available Gamma-band neuronal oscillation and synchronization with the range of 30-90 Hz are ubiquitous phenomenon across numerous brain areas and various species, and correlated with plenty of cognitive functions. The phase of the oscillation, as one aspect of CTC (Communication through Coherence hypothesis, underlies various functions for feature coding, memory processing and behaviour performing. The PPC (Pairwise Phase Consistency, an improved coherence measure, statistically quantifies the strength of phase synchronization. In order to evaluate the PPC and its relationships with input stimulus, neuronal activation and firing rate, a simplified spiking neuronal network is constructed to simulate orientation columns in primary visual cortex. If the input orientation stimulus is preferred for a certain orientation column, neurons within this corresponding column will obtain higher firing rate and stronger neuronal activation, which consequently engender higher PPC values, with higher PPC corresponding to higher firing rate. In addition, we investigate the PPC in time resolved analysis with a sliding window.

  13. Circadian and dark-pulse activation of orexin/hypocretin neurons

    Directory of Open Access Journals (Sweden)

    Marston Oliver J

    2008-12-01

    Full Text Available Temporal control of brain and behavioral states emerges as a consequence of the interaction between circadian and homeostatic neural circuits. This interaction permits the daily rhythm of sleep and wake, regulated in parallel by circadian cues originating from the suprachiasmatic nuclei (SCN and arousal-promoting signals arising from the orexin-containing neurons in the tuberal hypothalamus (TH. Intriguingly, the SCN circadian clock can be reset by arousal-promoting stimuli while activation of orexin/hypocretin neurons is believed to be under circadian control, suggesting the existence of a reciprocal relationship. Unfortunately, since orexin neurons are themselves activated by locomotor promoting cues, it is unclear how these two systems interact to regulate behavioral rhythms. Here mice were placed in conditions of constant light, which suppressed locomotor activity, but also revealed a highly pronounced circadian pattern in orexin neuronal activation. Significantly, activation of orexin neurons in the medial and lateral TH occurred prior to the onset of sustained wheel-running activity. Moreover, exposure to a 6 h dark pulse during the subjective day, a stimulus that promotes arousal and phase advances behavioral rhythms, activated neurons in the medial and lateral TH including those containing orexin. Concurrently, this stimulus suppressed SCN activity while activating cells in the median raphe. In contrast, dark pulse exposure during the subjective night did not reset SCN-controlled behavioral rhythms and caused a transient suppression of neuronal activation in the TH. Collectively these results demonstrate, for the first time, pronounced circadian control of orexin neuron activation and implicate recruitment of orexin cells in dark pulse resetting of the SCN circadian clock.

  14. Energy dependence on the electric activities of a neuron

    International Nuclear Information System (INIS)

    Song Xin-Lin; Ma Jun; Jin Wu-Yin

    2015-01-01

    A nonlinear circuit can be designed by using inductor, resistor, capacitor and other electric devices, and the electromagnetic field energy can be released from the circuit in the oscillating state. The generation of spikes or bursting states in neurons could be energetically a costly process. Based on the Helmholtz’s theorem, a Hamilton energy function is defined to detect the energy shift induced by transition of electric modes in a Hindmarsh–Rose neuron. It is found that the energy storage is dependent on the external forcing, and energy release is associated with the electric mode. As a result, the bursting state and chaotic state could be helpful to release the energy in the neuron quickly. (paper)

  15. Activation of AMPK by OSU53 protects spinal cord neurons from oxidative stress.

    Science.gov (United States)

    Xu, Jun; Wu, Liang; Zhang, Yiming; Gu, Huijie; Huang, Zhongyue; Zhou, Kaifeng; Yin, Xiaofan

    2017-12-22

    The present study tested the potential effect of OSU53, a novel AMPK activator, against hydrogen peroxide (H2O2)-induced spinal cord neuron damages. Treatment with OSU53 attenuated H2O2-induced death and apoptosis of primary murine spinal cord neurons. OSU53 activated AMPK signaling, which is required for its actions in spinal cord neurons. The AMPK inhibitor Compound C or AMPKα1 siRNA almost abolished OSU53-mediated neuroprotection against H2O2. On the other hand, sustained-activation of AMPK by introducing the constitutive-active AMPKα1 mimicked OSU53's actions, and protected spinal cord neurons from oxidative stress. OSU53 significantly attenuated H2O2-induced reactive oxygen species production, lipid peroxidation and DNA damages in spinal cord neurons. Additionally, OSU53 increased NADPH content and heme oxygenase-1 mRNA expression in H2O2-treated spinal cord neurons. Together, we indicate that targeted-activation of AMPK by OSU53 protects spinal cord neurons from oxidative stress.

  16. Possible involvement of 12-lipoxygenase activation in glucose-deprivation/reload-treated neurons.

    Science.gov (United States)

    Nagasawa, Kazuki; Kakuda, Taichi; Higashi, Youichirou; Fujimoto, Sadaki

    2007-12-18

    The aim of this study was to clarify whether 12-lipoxygenase (12-LOX) activation was involved in reactive oxygen species (ROS) generation, extensive poly(ADP-ribose) polymerase (PARP) activation and neuronal death induced by glucose-deprivation, followed by glucose-reload (GD/R). The decrease of neuronal viability and accumulation of poly(ADP-ribose) induced by GD/R were prevented 3-aminobenzamide, a representative PARP inhibitor, demonstrating this treatment protocol caused the same oxidative stress with the previously reported one. The PARP activation, ROS generation and decrease of neuron viability induced by GD/R treatment were almost completely abolished by an extracellular zinc chelator, CaEDTA. p47(phox), a cytosolic component of NADPH oxidase was translocated the membrane fraction by GD/R, indicating its activation, but it did not generate detectable ROS. Surprisingly, pharmacological inhibition of NADPH oxidase with apocynin and AEBSF further decreased the decreased neuron viability induced by GD/R. On the other hand, AA861, a 12-LOX inhibitor, prevented ROS generation and decrease of neuron viability caused by GD/R. Interestingly, an antioxidant, N-acetyl-l-cysteine rescued the neurons from GD/R-induced oxidative stress, implying effectiveness of antioxidant administration. These findings suggested that activation of 12-LOX, but not NADPH oxidase, following to zinc release might play an important role in ROS generation and decrease of viability in GD/R-treated neurons.

  17. Histamine induces microglia activation and dopaminergic neuronal toxicity via H1 receptor activation.

    Science.gov (United States)

    Rocha, Sandra M; Saraiva, Tatiana; Cristóvão, Ana C; Ferreira, Raquel; Santos, Tiago; Esteves, Marta; Saraiva, Cláudia; Je, Goun; Cortes, Luísa; Valero, Jorge; Alves, Gilberto; Klibanov, Alexander; Kim, Yoon-Seong; Bernardino, Liliana

    2016-06-04

    Histamine is an amine widely known as a peripheral inflammatory mediator and as a neurotransmitter in the central nervous system. Recently, it has been suggested that histamine acts as an innate modulator of microglial activity. Herein, we aimed to disclose the role of histamine in microglial phagocytic activity and reactive oxygen species (ROS) production and to explore the consequences of histamine-induced neuroinflammation in dopaminergic (DA) neuronal survival. The effect of histamine on phagocytosis was assessed both in vitro by using a murine N9 microglial cell line and primary microglial cell cultures and in vivo. Cells were exposed to IgG-opsonized latex beads or phosphatidylserine (PS) liposomes to evaluate Fcγ or PS receptor-mediated microglial phagocytosis, respectively. ROS production and protein levels of NADPH oxidases and Rac1 were assessed as a measure of oxidative stress. DA neuronal survival was evaluated in vivo by counting the number of tyrosine hydroxylase-positive neurons in the substantia nigra (SN) of mice. We found that histamine triggers microglial phagocytosis via histamine receptor 1 (H1R) activation and ROS production via H1R and H4R activation. By using apocynin, a broad NADPH oxidase (Nox) inhibitor, and Nox1 knockout mice, we found that the Nox1 signaling pathway is involved in both phagocytosis and ROS production induced by histamine in vitro. Interestingly, both apocynin and annexin V (used as inhibitor of PS-induced phagocytosis) fully abolished the DA neurotoxicity induced by the injection of histamine in the SN of adult mice in vivo. Blockade of H1R protected against histamine-induced Nox1 expression and death of DA neurons in vivo. Overall, our results highlight the relevance of histamine in the modulation of microglial activity that ultimately may interfere with neuronal survival in the context of Parkinson's disease (PD) and, eventually, other neurodegenerative diseases which are accompanied by microglia

  18. Roles of acid sphingomyelinase activation in neuronal cells apoptosis induced by microwave irradiation

    International Nuclear Information System (INIS)

    Zhang Lei; Xu Shangcheng; Zhang Guangbin; Yu Zhengping

    2009-01-01

    The present study is to examine the effect of microwave on acid sphingomyelinase (ASM) activity and expression, and to explore the role of ASM activation in neuronal cells apoptosis induced by microwave irradiation. Primary cultured hippocampal neurons were irradiated by 30 W/cm 2 microwave for 10 min, and ASM activity assay was used to investigate ASM activity alteration. RT-PCR and western blot were used to detect ASM mRNA and protein expression respectively. Apoptosis was observed by Hoechst 33342 fluorescence staining. ASM specific inhibitor imipramine was applied to inhibit ASM activation. It has been found that apoptosis rate of primary cultured hippocampal neurons increased significantly after microwave irradiation. ASM was activated while ASM mRNA and protein expression were upregulated in neurons after microwave irradiation. Pretreatment with imipramine could reverse neuronal apoptosis induced by microwave irradiation. Results show that microwave irradiation causes increment of ASM activation and expression and ASM activation is involved in microwave induced neuronal apoptosis. (authors)

  19. Basal ganglia neuronal activity during scanning eye movements in Parkinson's disease.

    Directory of Open Access Journals (Sweden)

    Tomáš Sieger

    Full Text Available The oculomotor role of the basal ganglia has been supported by extensive evidence, although their role in scanning eye movements is poorly understood. Nineteen Parkinsońs disease patients, which underwent implantation of deep brain stimulation electrodes, were investigated with simultaneous intraoperative microelectrode recordings and single channel electrooculography in a scanning eye movement task by viewing a series of colored pictures selected from the International Affective Picture System. Four patients additionally underwent a visually guided saccade task. Microelectrode recordings were analyzed selectively from the subthalamic nucleus, substantia nigra pars reticulata and from the globus pallidus by the WaveClus program which allowed for detection and sorting of individual neurons. The relationship between neuronal firing rate and eye movements was studied by crosscorrelation analysis. Out of 183 neurons that were detected, 130 were found in the subthalamic nucleus, 30 in the substantia nigra and 23 in the globus pallidus. Twenty percent of the neurons in each of these structures showed eye movement-related activity. Neurons related to scanning eye movements were mostly unrelated to the visually guided saccades. We conclude that a relatively large number of basal ganglia neurons are involved in eye motion control. Surprisingly, neurons related to scanning eye movements differed from neurons activated during saccades suggesting functional specialization and segregation of both systems for eye movement control.

  20. Basal ganglia neuronal activity during scanning eye movements in Parkinson's disease.

    Science.gov (United States)

    Sieger, Tomáš; Bonnet, Cecilia; Serranová, Tereza; Wild, Jiří; Novák, Daniel; Růžička, Filip; Urgošík, Dušan; Růžička, Evžen; Gaymard, Bertrand; Jech, Robert

    2013-01-01

    The oculomotor role of the basal ganglia has been supported by extensive evidence, although their role in scanning eye movements is poorly understood. Nineteen Parkinsońs disease patients, which underwent implantation of deep brain stimulation electrodes, were investigated with simultaneous intraoperative microelectrode recordings and single channel electrooculography in a scanning eye movement task by viewing a series of colored pictures selected from the International Affective Picture System. Four patients additionally underwent a visually guided saccade task. Microelectrode recordings were analyzed selectively from the subthalamic nucleus, substantia nigra pars reticulata and from the globus pallidus by the WaveClus program which allowed for detection and sorting of individual neurons. The relationship between neuronal firing rate and eye movements was studied by crosscorrelation analysis. Out of 183 neurons that were detected, 130 were found in the subthalamic nucleus, 30 in the substantia nigra and 23 in the globus pallidus. Twenty percent of the neurons in each of these structures showed eye movement-related activity. Neurons related to scanning eye movements were mostly unrelated to the visually guided saccades. We conclude that a relatively large number of basal ganglia neurons are involved in eye motion control. Surprisingly, neurons related to scanning eye movements differed from neurons activated during saccades suggesting functional specialization and segregation of both systems for eye movement control.

  1. Image-guided recording system for spatial and temporal mapping of neuronal activities in brain slice.

    Science.gov (United States)

    Choi, Geonho; Lee, Jeonghyeon; Kim, Hyeongeun; Jang, Jaemyung; Im, Changkyun; Jeon, Nooli; Jung, Woonggyu

    2018-03-01

    In this study, we introduce the novel image-guided recording system (IGRS) for efficient interpretation of neuronal activities in the brain slice. IGRS is designed to combine microelectrode array (MEA) and optical coherence tomography at the customized upright microscope. It allows to record multi-site neuronal signals and image of the volumetric brain anatomy in a single body configuration. For convenient interconnection between a brain image and neuronal signals, we developed the automatic mapping protocol that enables us to project acquired neuronal signals on a brain image. To evaluate the performance of IGRS, hippocampal signals of the brain slice were monitored, and corresponding with two-dimensional neuronal maps were successfully reconstructed. Our results indicated that IGRS and mapping protocol can provide the intuitive information regarding long-term and multi-sites neuronal signals. In particular, the temporal and spatial mapping capability of neuronal signals would be a very promising tool to observe and analyze the massive neuronal activity and connectivity in MEA-based electrophysiological studies. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Aberrant neuronal activity-induced signaling and gene expression in a mouse model of RASopathy.

    Directory of Open Access Journals (Sweden)

    Franziska Altmüller

    2017-03-01

    Full Text Available Noonan syndrome (NS is characterized by reduced growth, craniofacial abnormalities, congenital heart defects, and variable cognitive deficits. NS belongs to the RASopathies, genetic conditions linked to mutations in components and regulators of the Ras signaling pathway. Approximately 50% of NS cases are caused by mutations in PTPN11. However, the molecular mechanisms underlying cognitive impairments in NS patients are still poorly understood. Here, we report the generation and characterization of a new conditional mouse strain that expresses the overactive Ptpn11D61Y allele only in the forebrain. Unlike mice with a global expression of this mutation, this strain is viable and without severe systemic phenotype, but shows lower exploratory activity and reduced memory specificity, which is in line with a causal role of disturbed neuronal Ptpn11 signaling in the development of NS-linked cognitive deficits. To explore the underlying mechanisms we investigated the neuronal activity-regulated Ras signaling in brains and neuronal cultures derived from this model. We observed an altered surface expression and trafficking of synaptic glutamate receptors, which are crucial for hippocampal neuronal plasticity. Furthermore, we show that the neuronal activity-induced ERK signaling, as well as the consecutive regulation of gene expression are strongly perturbed. Microarray-based hippocampal gene expression profiling revealed profound differences in the basal state and upon stimulation of neuronal activity. The neuronal activity-dependent gene regulation was strongly attenuated in Ptpn11D61Y neurons. In silico analysis of functional networks revealed changes in the cellular signaling beyond the dysregulation of Ras/MAPK signaling that is nearly exclusively discussed in the context of NS at present. Importantly, changes in PI3K/AKT/mTOR and JAK/STAT signaling were experimentally confirmed. In summary, this study uncovers aberrant neuronal activity

  3. Genetic disruption of tubulin acetyltransferase, αTAT1, inhibits proliferation and invasion of colon cancer cells through decreases in Wnt1/β-catenin signaling

    International Nuclear Information System (INIS)

    Oh, Somi; You, Eunae; Ko, Panseon; Jeong, Jangho; Keum, Seula; Rhee, Sangmyung

    2017-01-01

    Microtubules are required for diverse cellular processes, and abnormal regulation of microtubule dynamics is closely associated with severe diseases including malignant tumors. In this study, we report that α-tubulin N-acetyltransferase (αTAT1), a regulator of α-tubulin acetylation, is required for colon cancer proliferation and invasion via regulation of Wnt1 and its downstream genes expression. Public transcriptome analysis showed that expression of ATAT1 is specifically upregulated in colon cancer tissue. A knockout (KO) of ATAT1 in the HCT116 colon cancer cell line, using the CRISPR/Cas9 system showed profound inhibition of proliferative and invasive activities of these cancer cells. Overexpression of αTAT1 or the acetyl-mimic K40Q α-tubulin mutant in αTAT1 KO cells restored the invasiveness, indicating that microtubule acetylation induced by αTAT1 is critical for HCT116 cell invasion. Analysis of colon cancer-related gene expression in αTAT1 KO cells revealed that the loss of αTAT1 decreased the expression of WNT1. Mechanistically, abrogation of tubulin acetylation by αTAT1 knockout inhibited localization of β-catenin to the plasma membrane and nucleus, thereby resulting in the downregulation of Wnt1 and of its downstream genes including CCND1, MMP-2, and MMP-9. These results suggest that αTAT1-mediated Wnt1 expression via microtubule acetylation is important for colon cancer progression. - Highlights: • Ablation of αTAT1 inhibits HCT116 colon cancer cell invasion. • αTAT1/acetylated microtubules regulate expression of Wnt1/β-catenin target genes. • Acetylated microtubules regulate cellular localization of β-catenin. • Loss of αTAT1 prevents Wnt1 from inducing β-catenin-dependent and -independent pathways.

  4. Effects of altered TatC proteins on protein secretion efficiency via the twin-arginine translocation pathway of Bacillus subtilis

    NARCIS (Netherlands)

    Eijlander, Robyn T.; Kolbusz, Magdalena A.; Berendsen, Erwin M.; Kuipers, Oscar P.

    Protein translocation via the Tat machinery in thylakoids and bacteria occurs through a cooperation between the TatA, TatB and TatC subunits, of which the TatC protein forms the initial Tat substrate-binding site. The Bacillus subtilis Tat machinery lacks TatB and comprises two separate TatAC

  5. GHRELIN ACTIVATES HYPOPHYSIOTROPIC CORTICOTROPIN-RELEASING FACTOR NEURONS INDEPENDENTLY OF THE ARCUATE NUCLEUS

    Science.gov (United States)

    Cabral, Agustina; Portiansky, Enrique; Sánchez-Jaramillo, Edith; Zigman, Jeffrey M.; Perello, Mario

    2016-01-01

    Previous work has established that the hormone ghrelin engages the hypothalamic-pituitary-adrenal neuroendocrine axis via activation of corticotropin-releasing factor (CRF) neurons of the hypothalamic paraventricular nucleus (PVN). The neuronal circuitry that mediates this effect of ghrelin is currently unknown. Here, we show that ghrelin-induced activation of PVN CRF neurons involved inhibition of γ-aminobutyric acid (GABA) inputs, likely via ghrelin binding sites that were localized at GABAergic terminals within the PVN. While ghrelin activated PVN CRF neurons in the presence of neuropeptide Y (NPY) receptor antagonists or in arcuate nucleus (ARC)-ablated mice, it failed to do it so in mice with ghrelin receptor expression limited to ARC agouti gene related protein (AgRP)/NPY neurons. These data support the notion that ghrelin activates PVN CRF neurons via inhibition of local GABAergic tone, in an ARC-independent manner. Furthermore, these data suggest that the neuronal circuits mediating ghrelin’s orexigenic action vs. its role as a stress signal are anatomically dissociated. PMID:26874559

  6. Atomic basis for therapeutic activation of neuronal potassium channels

    DEFF Research Database (Denmark)

    Kim, Robin Y; Yau, Michael C; Galpin, Jason D

    2015-01-01

    Retigabine is a recently approved anticonvulsant that acts by potentiating neuronal M-current generated by KCNQ2-5 channels, interacting with a conserved Trp residue in the channel pore domain. Using unnatural amino-acid mutagenesis, we subtly altered the properties of this Trp to reveal specific...

  7. Multiplicative multifractal modeling and discrimination of human neuronal activity

    International Nuclear Information System (INIS)

    Zheng Yi; Gao Jianbo; Sanchez, Justin C.; Principe, Jose C.; Okun, Michael S.

    2005-01-01

    Understanding neuronal firing patterns is one of the most important problems in theoretical neuroscience. It is also very important for clinical neurosurgery. In this Letter, we introduce a computational procedure to examine whether neuronal firing recordings could be characterized by cascade multiplicative multifractals. By analyzing raw recording data as well as generated spike train data from 3 patients collected in two brain areas, the globus pallidus externa (GPe) and the globus pallidus interna (GPi), we show that the neural firings are consistent with a multifractal process over certain time scale range (t 1 ,t 2 ), where t 1 is argued to be not smaller than the mean inter-spike-interval of neuronal firings, while t 2 may be related to the time that neuronal signals propagate in the major neural branching structures pertinent to GPi and GPe. The generalized dimension spectrum D q effectively differentiates the two brain areas, both intra- and inter-patients. For distinguishing between GPe and GPi, it is further shown that the cascade model is more effective than the methods recently examined by Schiff et al. as well as the Fano factor analysis. Therefore, the methodology may be useful in developing computer aided tools to help clinicians perform precision neurosurgery in the operating room

  8. Estimation of the neuronal activation using fMRI data: An observer-based approach

    KAUST Repository

    Laleg-Kirati, Taous-Meriem; Arabi, Hossein; Tadjine, Mohamed; Zayane, Chadia

    2013-01-01

    This paper deals with the estimation of the neuronal activation and some unmeasured physiological information using the Blood Oxygenation Level Dependent (BOLD) signal measured using functional Magnetic Resonance Imaging (fMRI). We propose to use

  9. Neuron-derived IgG protects dopaminergic neurons from insult by 6-OHDA and activates microglia through the FcγR I and TLR4 pathways.

    Science.gov (United States)

    Zhang, Jie; Niu, Na; Wang, Mingyu; McNutt, Michael A; Zhang, Donghong; Zhang, Baogang; Lu, Shijun; Liu, Yuqing; Liu, Zhihui

    2013-08-01

    Oxidative and immune attacks from the environment or microglia have been implicated in the loss of dopaminergic neurons of Parkinson's disease. The role of IgG which is an important immunologic molecule in the process of Parkinson's disease has been unclear. Evidence suggests that IgG can be produced by neurons in addition to its traditionally recognized source B lymphocytes, but its function in neurons is poorly understood. In this study, extensive expression of neuron-derived IgG was demonstrated in dopaminergic neurons of human and rat mesencephalon. With an in vitro Parkinson's disease model, we found that neuron-derived IgG can improve the survival and reduce apoptosis of dopaminergic neurons induced by 6-hydroxydopamine toxicity, and also depress the release of NO from microglia triggered by 6-hydroxydopamine. Expression of TNF-α and IL-10 in microglia was elevated to protective levels by neuron-derived IgG at a physiologic level via the FcγR I and TLR4 pathways and microglial activation could be attenuated by IgG blocking. All these data suggested that neuron-derived IgG may exert a self-protective function by activating microglia properly, and IgG may be involved in maintaining immunity homeostasis in the central nervous system and serve as an active factor under pathological conditions such as Parkinson's disease. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

  10. Naphthazarin protects against glutamate-induced neuronal death via activation of the Nrf2/ARE pathway.

    Science.gov (United States)

    Son, Tae Gen; Kawamoto, Elisa M; Yu, Qian-Sheng; Greig, Nigel H; Mattson, Mark P; Camandola, Simonetta

    2013-04-19

    Nuclear factor E2-related factor 2 (Nrf2)/antioxidant response element (ARE) pathway is an important cellular stress response pathway involved in neuroprotection. We previously screened several natural phytochemicals and identified plumbagin as a novel activator of the Nrf2/ARE pathway that can protect neurons against ischemic injury. Here we extended our studies to natural and synthetic derivatives of plumbagin. We found that 5,8-dimethoxy-1,4-naphthoquinone (naphthazarin) is a potent activator of the Nrf2/ARE pathway, up-regulates the expression of Nrf2-driven genes in primary neuronal and glial cultures, and protects neurons against glutamate-induced excitotoxicity. Published by Elsevier Inc.

  11. Stress and Sucrose Intake Modulate Neuronal Activity in the Anterior Hypothalamic Area in Rats.

    Science.gov (United States)

    Mitra, Arojit; Guèvremont, Geneviève; Timofeeva, Elena

    2016-01-01

    The anterior hypothalamic area (AHA) is an important integrative relay structure for a variety of autonomic, endocrine, and behavioral responses including feeding behavior and response to stress. However, changes in the activity of the AHA neurons during stress and feeding in freely moving rats are not clear. The present study investigated the firing rate and burst activity of neurons in the central nucleus of the AHA (cAHA) during sucrose intake in non-stressful conditions and after acute stress in freely behaving rats. Rats were implanted with micro-electrodes into the cAHA, and extracellular multi-unit activity was recorded during 1-h access to 10% sucrose in non-stressful conditions or after acute foot shock stress. Acute stress significantly reduced sucrose intake, total sucrose lick number, and lick frequency in licking clusters, and increased inter-lick intervals. At the cluster start (CS) of sucrose licking, the cAHA neurons increased (CS-excited, 20% of the recorded neurons), decreased (CS-inhibited, 42% of the neurons) or did not change (CS-nonresponsive, 38% of the neurons) their firing rate. Stress resulted in a significant increase in the firing rate of the CS-inhibited neurons by decreasing inter-spike intervals within the burst firing of these neurons. This increase in the stress-induced firing rate of the CS-inhibited neurons was accompanied by a disruption of the correlation between the firing rate of CS-inhibited and CS-nonresponsive neurons that was observed in non-stressful conditions. Stress did not affect the firing rate of the CS-excited and CS-nonresponsive neurons. However, stress changed the pattern of burst firing of the CS-excited and CS-nonresponsive neurons by decreasing and increasing the burst number in the CS-excited and CS-nonresponsive neurons, respectively. These results suggest that the cAHA neurons integrate the signals related to stress and intake of palatable food and play a role in the stress- and eating-related circuitry.

  12. Are dragon-king neuronal avalanches dungeons for self-organized brain activity?

    Science.gov (United States)

    de Arcangelis, L.

    2012-05-01

    Recent experiments have detected a novel form of spontaneous neuronal activity both in vitro and in vivo: neuronal avalanches. The statistical properties of this activity are typical of critical phenomena, with power laws characterizing the distributions of avalanche size and duration. A critical behaviour for the spontaneous brain activity has important consequences on stimulated activity and learning. Very interestingly, these statistical properties can be altered in significant ways in epilepsy and by pharmacological manipulations. In particular, there can be an increase in the number of large events anticipated by the power law, referred to herein as dragon-king avalanches. This behaviour, as verified by numerical models, can originate from a number of different mechanisms. For instance, it is observed experimentally that the emergence of a critical behaviour depends on the subtle balance between excitatory and inhibitory mechanisms acting in the system. Perturbing this balance, by increasing either synaptic excitation or the incidence of depolarized neuronal up-states causes frequent dragon-king avalanches. Conversely, an unbalanced GABAergic inhibition or long periods of low activity in the network give rise to sub-critical behaviour. Moreover, the existence of power laws, common to other stochastic processes, like earthquakes or solar flares, suggests that correlations are relevant in these phenomena. The dragon-king avalanches may then also be the expression of pathological correlations leading to frequent avalanches encompassing all neurons. We will review the statistics of neuronal avalanches in experimental systems. We then present numerical simulations of a neuronal network model introducing within the self-organized criticality framework ingredients from the physiology of real neurons, as the refractory period, synaptic plasticity and inhibitory synapses. The avalanche critical behaviour and the role of dragon-king avalanches will be discussed in

  13. The mast cell degranulator compound 48/80 directly activates neurons.

    Directory of Open Access Journals (Sweden)

    Michael Schemann

    Full Text Available BACKGROUND: Compound 48/80 is widely used in animal and tissue models as a "selective" mast cell activator. With this study we demonstrate that compound 48/80 also directly activates enteric neurons and visceral afferents. METHODOLOGY/PRINCIPAL FINDINGS: We used in vivo recordings from extrinsic intestinal afferents together with Ca(++ imaging from primary cultures of DRG and nodose neurons. Enteric neuronal activation was examined by Ca(++ and voltage sensitive dye imaging in isolated gut preparations and primary cultures of enteric neurons. Intraluminal application of compound 48/80 evoked marked afferent firing which desensitized on subsequent administration. In egg albumen-sensitized animals, intraluminal antigen evoked a similar pattern of afferent activation which also desensitized on subsequent exposure to antigen. In cross-desensitization experiments prior administration of compound 48/80 failed to influence the mast cell mediated response. Application of 1 and 10 µg/ml compound 48/80 evoked spike discharge and Ca(++ transients in enteric neurons. The same nerve activating effect was observed in primary cultures of DRG and nodose ganglion cells. Enteric neuron cultures were devoid of mast cells confirmed by negative staining for c-kit or toluidine blue. In addition, in cultured enteric neurons the excitatory action of compound 48/80 was preserved in the presence of histamine H(1 and H(2 antagonists. The mast cell stabilizer cromolyn attenuated compound 48/80 and nicotine evoked Ca(++ transients in mast cell-free enteric neuron cultures. CONCLUSIONS/SIGNIFICANCE: The results showed direct excitatory action of compound 48/80 on enteric neurons and visceral afferents. Therefore, functional changes measured in tissue or animal models may involve a mast cell independent effect of compound 48/80 and cromolyn.

  14. Dehydration-induced modulation of κ-opioid inhibition of vasopressin neurone activity

    Science.gov (United States)

    Scott, Victoria; Bishop, Valerie R; Leng, Gareth; Brown, Colin H

    2009-01-01

    Dehydration increases vasopressin (antidiuretic hormone) secretion from the posterior pituitary gland to reduce water loss in the urine. Vasopressin secretion is determined by action potential firing in vasopressin neurones, which can exhibit continuous, phasic (alternating periods of activity and silence), or irregular activity. Autocrine κ-opioid inhibition contributes to the generation of activity patterning of vasopressin neurones under basal conditions and so we used in vivo extracellular single unit recording to test the hypothesis that changes in autocrine κ-opioid inhibition drive changes in activity patterning of vasopressin neurones during dehydration. Dehydration increased the firing rate of rat vasopressin neurones displaying continuous activity (from 7.1 ± 0.5 to 9.0 ± 0.6 spikes s−1) and phasic activity (from 4.2 ± 0.7 to 7.8 ± 0.9 spikes s−1), but not those displaying irregular activity. The dehydration-induced increase in phasic activity was via an increase in intraburst firing rate. The selective κ-opioid receptor antagonist nor-binaltorphimine increased the firing rate of phasic neurones in non-dehydrated rats (from 3.4 ± 0.8 to 5.3 ± 0.6 spikes s−1) and dehydrated rats (from 6.4 ± 0.5 to 9.1 ± 1.2 spikes s−1), indicating that κ-opioid feedback inhibition of phasic bursts is maintained during dehydration. In a separate series of experiments, prodynorphin mRNA expression was increased in vasopressin neurones of hyperosmotic rats, compared to hypo-osmotic rats. Hence, it appears that dynorphin expression in vasopressin neurones undergoes dynamic changes in proportion to the required secretion of vasopressin so that, even under stimulated conditions, autocrine feedback inhibition of vasopressin neurones prevents over-excitation. PMID:19822541

  15. Knockdown of GAD67 protein levels normalizes neuronal activity in a rat model of Parkinson's disease

    DEFF Research Database (Denmark)

    Horvath, Lazlo; van Marion, Ingrid; Taï, Khalid

    2011-01-01

    Dopamine depletion of the striatum is one of the hallmarks of Parkinson's disease. The loss of dopamine upregulates GAD67 expression in the striatal projection neurons and causes other changes in the activity of the basal ganglia circuit.......Dopamine depletion of the striatum is one of the hallmarks of Parkinson's disease. The loss of dopamine upregulates GAD67 expression in the striatal projection neurons and causes other changes in the activity of the basal ganglia circuit....

  16. Orexin receptor activation generates gamma band input to cholinergic and serotonergic arousal system neurons and drives an intrinsic Ca2+-dependent resonance in LDT and PPT cholinergic neurons.

    Directory of Open Access Journals (Sweden)

    Masaru eIshibashi

    2015-06-01

    Full Text Available A hallmark of the waking state is a shift in EEG power to higher frequencies with epochs of synchronized intracortical gamma activity (30-60 Hz - a process associated with high-level cognitive functions. The ascending arousal system, including cholinergic laterodorsal (LDT and pedunculopontine (PPT tegmental neurons and serotonergic dorsal raphe (DR neurons, promotes this state. Recently, this system has been proposed as a gamma wave generator, in part, because some neurons produce high-threshold, Ca2+-dependent oscillations at gamma frequencies. However, it is not known whether arousal-related inputs to these neurons generate such oscillations, or whether such oscillations are ever transmitted to neuronal targets. Since key arousal input arises from hypothalamic orexin (hypocretin neurons, we investigated whether the unusually noisy, depolarizing orexin current could provide significant gamma input to cholinergic and serotonergic neurons, and whether such input could drive Ca2+-dependent oscillations. Whole-cell recordings in brain slices were obtained from mice expressing Cre-induced fluorescence in cholinergic LDT and PPT, and serotonergic DR neurons. After first quantifying reporter expression accuracy in cholinergic and serotonergic neurons, we found that the orexin current produced significant high frequency, including gamma, input to both cholinergic and serotonergic neurons. Then, by using a dynamic clamp, we found that adding a noisy orexin conductance to cholinergic neurons induced a Ca2+-dependent resonance that peaked in the theta and alpha frequency range (4 - 14 Hz and extended up to 100 Hz. We propose that this orexin current noise and the Ca2+ dependent resonance work synergistically to boost the encoding of high-frequency synaptic inputs into action potentials and to help ensure cholinergic neurons fire during EEG activation. This activity could reinforce thalamocortical states supporting arousal, REM sleep and intracortical

  17. Biocompatible anionic polymeric microspheres as priming delivery system for effetive HIV/AIDS Tat-based vaccines.

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    Fausto Titti

    Full Text Available Here we describe a prime-boost regimen of vaccination in Macaca fascicularis that combines priming with novel anionic microspheres designed to deliver the biologically active HIV-1 Tat protein and boosting with Tat in Alum. This regimen of immunization modulated the IgG subclass profile and elicited a balanced Th1-Th2 type of humoral and cellular responses. Remarkably, following intravenous challenge with SHIV89.6Pcy243, vaccinees significantly blunted acute viremia, as compared to control monkeys, and this control was associated with significantly lower CD4+ T cell depletion rate during the acute phase of infection and higher ability to resume the CD4+ T cell counts in the post-acute and chronic phases of infection. The long lasting control of viremia was associated with the persistence of high titers anti-Tat antibodies whose profile clearly distinguished vaccinees in controllers and viremics. Controllers, as opposed to vaccinated and viremic cynos, exhibited significantly higher pre-challenge antibody responses to peptides spanning the glutamine-rich and the RGD-integrin-binding regions of Tat. Finally, among vaccinees, titers of anti-Tat IgG1, IgG3 and IgG4 subclasses had a significant association with control of viremia in the acute and post-acute phases of infection. Altogether these findings indicate that the Tat/H1D/Alum regimen of immunization holds promise for next generation vaccines with Tat protein or other proteins for which maintenance of the native conformation and activity are critical for optimal immunogenicity. Our results also provide novel information on the role of anti-Tat responses in the prevention of HIV pathogenesis and for the design of new vaccine candidates.

  18. Activation of 5-HT7 receptors reverses NMDA-R-dependent LTD by activating PKA in medial vestibular neurons.

    Science.gov (United States)

    Li, Yan-Hai; Han, Lei; Wu, Kenneth Lap Kei; Chan, Ying-Shing

    2017-09-01

    The medial vestibular nucleus (MVN) is a major output station for neurons that project to the vestibulo-spinal pathway. MVN neurons show capacity for long-term depression (LTD) during the juvenile period. We investigated LTD of MVN neurons using whole-cell patch-clamp recordings. High frequency stimulation (HFS) robustly induced LTD in 90% of type B neurons in the MVN, while only 10% of type A neurons were responsive, indicating that type B neurons are the major contributors to LTD in the MVN. The neuromodulator serotonin (5-HT) is known to modulate LTD in neural circuits of the cerebral cortex and the hippocampus. We therefore aim to determine the action of 5-HT on the LTD of type B MVN neurons and elucidate the relevant 5-HT receptor subtypes responsible for its action. Using specific agonists and antagonists of 5-HT receptors, we found that selective activation of 5-HT 7 receptor in type B neurons in the MVN of juvenile (P13-16) rats completely abolished NMDA-receptor-mediated LTD in a protein kinase A (PKA)-dependent manner. Our finding that 5-HT restricts plasticity of type B MVN neurons via 5-HT 7 receptors offers a mechanism whereby vestibular tuning contributes to the maturation of the vestibulo-spinal circuit and highlights the role of 5-HT in postural control. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Codimension-two bifurcation analysis on firing activities in Chay neuron model

    International Nuclear Information System (INIS)

    Duan Lixia; Lu Qishao

    2006-01-01

    Using codimension-two bifurcation analysis in the Chay neuron model, the relationship between the electric activities and the parameters of neurons is revealed. The whole parameter space is divided into two parts, that is, the firing and silence regions of neurons. It is found that the transition sets between firing and silence regions are composed of the Hopf bifurcation curves of equilibrium states and the saddle-node bifurcation curves of limit cycles, with some codimension-two bifurcation points. The transitions from silence to firing in neurons are due to the Hopf bifurcation or the fold limit cycle bifurcation, but the codimension-two singularities lead to complexity in dynamical behaviour of neuronal firing

  20. Codimension-two bifurcation analysis on firing activities in Chay neuron model

    Energy Technology Data Exchange (ETDEWEB)

    Duan Lixia [School of Science, Beijing University of Aeronautics and Astronautics, Beijing 100083 (China); Lu Qishao [School of Science, Beijing University of Aeronautics and Astronautics, Beijing 100083 (China)]. E-mail: qishaolu@hotmail.com

    2006-12-15

    Using codimension-two bifurcation analysis in the Chay neuron model, the relationship between the electric activities and the parameters of neurons is revealed. The whole parameter space is divided into two parts, that is, the firing and silence regions of neurons. It is found that the transition sets between firing and silence regions are composed of the Hopf bifurcation curves of equilibrium states and the saddle-node bifurcation curves of limit cycles, with some codimension-two bifurcation points. The transitions from silence to firing in neurons are due to the Hopf bifurcation or the fold limit cycle bifurcation, but the codimension-two singularities lead to complexity in dynamical behaviour of neuronal firing.

  1. Activation of hypothalamic RIP-Cre neurons promotes beiging of WAT via sympathetic nervous system.

    Science.gov (United States)

    Wang, Baile; Li, Ang; Li, Xiaomu; Ho, Philip Wl; Wu, Donghai; Wang, Xiaoqi; Liu, Zhuohao; Wu, Kelvin Kl; Yau, Sonata Sy; Xu, Aimin; Cheng, Kenneth Ky

    2018-04-01

    Activation of brown adipose tissue (BAT) and beige fat by cold increases energy expenditure. Although their activation is known to be differentially regulated in part by hypothalamus, the underlying neural pathways and populations remain poorly characterized. Here, we show that activation of rat-insulin-promoter-Cre (RIP-Cre) neurons in ventromedial hypothalamus (VMH) preferentially promotes recruitment of beige fat via a selective control of sympathetic nervous system (SNS) outflow to subcutaneous white adipose tissue (sWAT), but has no effect on BAT Genetic ablation of APPL2 in RIP-Cre neurons diminishes beiging in sWAT without affecting BAT, leading to cold intolerance and obesity in mice. Such defects are reversed by activation of RIP-Cre neurons, inactivation of VMH AMPK, or treatment with a β3-adrenergic receptor agonist. Hypothalamic APPL2 enhances neuronal activation in VMH RIP-Cre neurons and raphe pallidus, thereby eliciting SNS outflow to sWAT and subsequent beiging. These data suggest that beige fat can be selectively activated by VMH RIP-Cre neurons, in which the APPL2-AMPK signaling axis is crucial for this defending mechanism to cold and obesity. © 2018 The Authors.

  2. CAMKII activation is not required for maintenance of learning-induced enhancement of neuronal excitability.

    Directory of Open Access Journals (Sweden)

    Ori Liraz

    Full Text Available Pyramidal neurons in the piriform cortex from olfactory-discrimination trained rats show enhanced intrinsic neuronal excitability that lasts for several days after learning. Such enhanced intrinsic excitability is mediated by long-term reduction in the post-burst after-hyperpolarization (AHP which is generated by repetitive spike firing. AHP reduction is due to decreased conductance of a calcium-dependent potassium current, the sI(AHP. We have previously shown that learning-induced AHP reduction is maintained by persistent protein kinase C (PKC and extracellular regulated kinase (ERK activation. However, the molecular machinery underlying this long-lasting modulation of intrinsic excitability is yet to be fully described. Here we examine whether the CaMKII, which is known to be crucial in learning, memory and synaptic plasticity processes, is instrumental for the maintenance of learning-induced AHP reduction. KN93, that selectively blocks CaMKII autophosphorylation at Thr286, reduced the AHP in neurons from trained and control rat to the same extent. Consequently, the differences in AHP amplitude and neuronal adaptation between neurons from trained rats and controls remained. Accordingly, the level of activated CaMKII was similar in pirifrom cortex samples taken form trained and control rats. Our data show that although CaMKII modulates the amplitude of AHP of pyramidal neurons in the piriform cortex, its activation is not required for maintaining learning-induced enhancement of neuronal excitability.

  3. Vulnerability to glutamate toxicity of dopaminergic neurons is dependent on endogenous dopamine and MAPK activation.

    Science.gov (United States)

    Izumi, Yasuhiko; Yamamoto, Noriyuki; Matsuo, Takaaki; Wakita, Seiko; Takeuchi, Hiroki; Kume, Toshiaki; Katsuki, Hiroshi; Sawada, Hideyuki; Akaike, Akinori

    2009-07-01

    Dopaminergic neurons are more vulnerable than other types of neurons in cases of Parkinson disease and ischemic brain disease. An increasing amount of evidence suggests that endogenous dopamine plays a role in the vulnerability of dopaminergic neurons. Although glutamate toxicity contributes to the pathogenesis of these disorders, the sensitivity of dopaminergic neurons to glutamate toxicity has not been clarified. In this study, we demonstrated that dopaminergic neurons were preferentially affected by glutamate toxicity in rat mesencephalic cultures. Glutamate toxicity in dopaminergic neurons was blocked by inhibiting extracellular signal-regulated kinase (ERK), c-jun N-terminal kinase, and p38 MAPK. Furthermore, depletion of dopamine by alpha-methyl-dl-p-tyrosine methyl ester (alpha-MT), an inhibitor of tyrosine hydroxylase (TH), protected dopaminergic neurons from the neurotoxicity. Exposure to glutamate facilitated phosphoryration of TH at Ser31 by ERK, which contributes to the increased TH activity. Inhibition of ERK had no additive effect on the protection offered by alpha-MT, whereas alpha-MT and c-jun N-terminal kinase or p38 MAPK inhibitors had additive effects and yielded full protection. These data suggest that endogenous dopamine is responsible for the vulnerability to glutamate toxicity of dopaminergic neurons and one of the mechanisms may be an enhancement of dopamine synthesis mediated by ERK.

  4. Palmitoylethanolamide Blunts Amyloid-β42-Induced Astrocyte Activation and Improves Neuronal Survival in Primary Mouse Cortical Astrocyte-Neuron Co-Cultures.

    Science.gov (United States)

    Beggiato, Sarah; Borelli, Andrea Celeste; Ferraro, Luca; Tanganelli, Sergio; Antonelli, Tiziana; Tomasini, Maria Cristina

    2018-01-01

    Based on the pivotal role of astrocytes in brain homeostasis and the strong metabolic cooperation existing between neurons and astrocytes, it has been suggested that astrocytic dysfunctions might cause and/or contribute to neuroinflammation and neurodegenerative processes. Therapeutic approaches aimed at both neuroprotection and neuroinflammation reduction may prove particularly effective in slowing the progression of these diseases. The endogenous lipid mediator palmitoylethanolamide (PEA) displayed neuroprotective and anti(neuro)inflammatory properties, and demonstrated interesting potential as a novel treatment for Alzheimer's disease. We firstly evaluated whether astrocytes could participate in regulating the Aβ42-induced neuronal damage, by using primary mouse astrocytes cell cultures and mixed astrocytes-neurons cultures. Furthermore, the possible protective effects of PEA against Aβ42-induced neuronal toxicity have also been investigated by evaluating neuronal viability, apoptosis, and morphometric parameters. The presence of astrocytes pre-exposed to Aβ42 (0.5μM; 24 h) induced a reduction of neuronal viability in primary mouse astrocytes-neurons co-cultures. Furthermore, under these experimental conditions, an increase in the number of neuronal apoptotic nuclei and a decrease in the number of MAP-2 positive neurons were observed. Finally, astrocytic Aβ42 pre-exposure induced an increase in the number of neurite aggregations/100μm as compared to control (i.e., untreated) astrocytes-neurons co-cultures. These effects were not observed in neurons cultured in the presence of astrocytes pre-exposed to PEA (0.1μM), applied 1 h before and maintained during Aβ42 treatment. Astrocytes contribute to Aβ42-induced neurotoxicity and PEA, by blunting Aβ42-induced astrocyte activation, improved neuronal survival in mouse astrocyte-neuron co-cultures.

  5. Activity of Tachykinin1-Expressing Pet1 Raphe Neurons Modulates the Respiratory Chemoreflex.

    Science.gov (United States)

    Hennessy, Morgan L; Corcoran, Andrea E; Brust, Rachael D; Chang, YoonJeung; Nattie, Eugene E; Dymecki, Susan M

    2017-02-15

    Homeostatic control of breathing, heart rate, and body temperature relies on circuits within the brainstem modulated by the neurotransmitter serotonin (5-HT). Mounting evidence points to specialized neuronal subtypes within the serotonergic neuronal system, borne out in functional studies, for the modulation of distinct facets of homeostasis. Such functional differences, read out at the organismal level, are likely subserved by differences among 5-HT neuron subtypes at the cellular and molecular levels, including differences in the capacity to coexpress other neurotransmitters such as glutamate, GABA, thyrotropin releasing hormone, and substance P encoded by the Tachykinin-1 ( Tac1 ) gene. Here, we characterize in mice a 5-HT neuron subtype identified by expression of Tac1 and the serotonergic transcription factor gene Pet1 , referred to as the Tac1-Pet1 neuron subtype. Transgenic cell labeling showed Tac1-Pet1 soma resident largely in the caudal medulla. Chemogenetic [clozapine -N- oxide (CNO)-hM4Di] perturbation of Tac1-Pet1 neuron activity blunted the ventilatory response of the respiratory CO 2 chemoreflex, which normally augments ventilation in response to hypercapnic acidosis to restore normal pH and PCO 2 Tac1-Pet1 axonal boutons were found localized to brainstem areas implicated in respiratory modulation, with highest density in motor regions. These findings demonstrate that the activity of a Pet1 neuron subtype with the potential to release both 5-HT and substance P is necessary for normal respiratory dynamics, perhaps via motor outputs that engage muscles of respiration and maintain airway patency. These Tac1-Pet1 neurons may act downstream of Egr2-Pet1 serotonergic neurons, which were previously established in respiratory chemoreception, but do not innervate respiratory motor nuclei. SIGNIFICANCE STATEMENT Serotonin (5-HT) neurons modulate physiological processes and behaviors as diverse as body temperature, respiration, aggression, and mood. Using

  6. Hydralazine administration activates sympathetic preganglionic neurons whose activity mobilizes glucose and increases cardiovascular function.

    Science.gov (United States)

    Parker, Lindsay M; Damanhuri, Hanafi A; Fletcher, Sophie P S; Goodchild, Ann K

    2015-04-16

    Hypotensive drugs have been used to identify central neurons that mediate compensatory baroreceptor reflex responses. Such drugs also increase blood glucose. Our aim was to identify the neurochemical phenotypes of sympathetic preganglionic neurons (SPN) and adrenal chromaffin cells activated following hydralazine (HDZ; 10mg/kg) administration in rats, and utilize this and SPN target organ destination to ascribe their function as cardiovascular or glucose regulating. Blood glucose was measured and adrenal chromaffin cell activation was assessed using c-Fos immunoreactivity (-ir) and phosphorylation of tyrosine hydroxylase, respectively. The activation and neurochemical phenotype of SPN innervating the adrenal glands and celiac ganglia were determined using the retrograde tracer cholera toxin B subunit, in combination with in situ hybridization and immunohistochemistry. Blood glucose was elevated at multiple time points following HDZ administration but little evidence of chromaffin cell activation was seen suggesting non-adrenal mechanisms contribute to the sustained hyperglycemia. 16±0.1% of T4-T11 SPN contained c-Fos and of these: 24.3±1.4% projected to adrenal glands and 29±5.5% projected to celiac ganglia with the rest innervating other targets. 62.8±1.4% of SPN innervating adrenal glands were activated and 29.9±3.3% expressed PPE mRNA whereas 53.2±8.6% of SPN innervating celiac ganglia were activated and 31.2±8.8% expressed PPE mRNA. CART-ir SPN innervating each target were also activated and did not co-express PPE mRNA. Neurochemical coding reveals that HDZ administration activates both PPE+SPN, whose activity increase glucose mobilization causing hyperglycemia, as well as CART+SPN whose activity drive vasomotor responses mediated by baroreceptor unloading to raise vascular tone and heart rate. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Calcium activity of upper thoracic dorsal root ganglion neurons in zucker diabetic Fatty rats

    DEFF Research Database (Denmark)

    Ghorbani, Marie Louise; Nyborg, Niels C B; Fjalland, Bjarne

    2013-01-01

    The aim of the present study was to examine the calcium activity of C8-T5 dorsal root ganglion (DRG) neurons from Zucker diabetic fatty rats. In total, 8 diabetic ZDF fatty animals and 8 age-matched control ZDF lean rats were employed in the study. C8-T5 dorsal root ganglia were isolated bilatera......The aim of the present study was to examine the calcium activity of C8-T5 dorsal root ganglion (DRG) neurons from Zucker diabetic fatty rats. In total, 8 diabetic ZDF fatty animals and 8 age-matched control ZDF lean rats were employed in the study. C8-T5 dorsal root ganglia were isolated...... in calcium activity of the DRG neurons were found, potentially indicating altered neuronal responses during myocardial ischemia....

  8. Effect of Intravasclar Influsion of Endogenous Pyrogen or Prostaglandin E2 on Neuronal Activity of Rat's Hypothalamus

    OpenAIRE

    Sakata, Yoshiyuki; Watanabe, Tatsuo; Morimoto, Akio; Murakami, Naotoshi

    1989-01-01

    We investigated the effects of intracarotid infusion of prostaglandin E2 or intravenous infusion of an endogenous pyrogen on the neuronal activity of the neuronal activity of the preoptic and anterior hypothalamic (PO/AH) region in rats. The present results suggest that thermore sponsive neurons of the PO/AH region respond well to intravascular application of prostaglandin E2 or the endogenous pyrogen, compared with thermally insensive neurons. Intravenous infusion of the endogenous pyrogen a...

  9. Neuronal MHC Class I Expression Is Regulated by Activity Driven Calcium Signaling.

    Directory of Open Access Journals (Sweden)

    Dan Lv

    Full Text Available MHC class I (MHC-I molecules are important components of the immune system. Recently MHC-I have been reported to also play important roles in brain development and synaptic plasticity. In this study, we examine the molecular mechanism(s underlying activity-dependent MHC-I expression using hippocampal neurons. Here we report that neuronal expression level of MHC-I is dynamically regulated during hippocampal development after birth in vivo. Kainic acid (KA treatment significantly increases the expression of MHC-I in cultured hippocampal neurons in vitro, suggesting that MHC-I expression is regulated by neuronal activity. In addition, KA stimulation decreased the expression of pre- and post-synaptic proteins. This down-regulation is prevented by addition of an MHC-I antibody to KA treated neurons. Further studies demonstrate that calcium-dependent protein kinase C (PKC is important in relaying KA simulation activation signals to up-regulated MHC-I expression. This signaling cascade relies on activation of the MAPK pathway, which leads to increased phosphorylation of CREB and NF-κB p65 while also enhancing the expression of IRF-1. Together, these results suggest that expression of MHC-I in hippocampal neurons is driven by Ca2+ regulated activation of the MAPK signaling transduction cascade.

  10. Cloning, Expression and Purification of the Recombinant HIV-1 Tat-Nef Fusion Protein in Prokaryotic Expression System

    Directory of Open Access Journals (Sweden)

    Somayeh Kadkhodayan

    2016-07-01

    Full Text Available Abstract Background: Nef is one of the HIV-1 critical proteins, because it is essential for viral replication and AIDS disease progression and induction of immune response against it can partially inhibit viral infection. Moreover, a domain of the HIV-1 Trans-Activator of Transcription (Tat, 48-60 aa could act as a cell penetrating peptide (CPP. In current study, cloning and expression of Tat-Nef fusion protein was performed in E. coli for the first time. The protein expression was confirmed by western blot analysis and was purified using reverse staining method. Materials and Methods: In this experimental study, primarily, cloning of Tat-Nef fusion gene was done in pGEX6p2 expression vector. Then, the expression of Tat-Nef recombinat protein in E.coli BL21 (DE3 strain was performed by using IPTG inducer. The protein expression was confirmed by SDS-PAGE and western blotting using anti-Nef monoclonal antibody. Then, the recombinant fusion protein was purified from gel using reverse staining method. Results: The results of PCR analysis and enzyme digestion showed a clear band of ~ 726 bp in agarose gel indicating the correct Tat-Nef fusion cloning in pGEX6p2 prokaryotic expression vector. In addition, a 54 kDa band of Tat-Nef on SDS-PAGE revealed Tat-Nef protein expression that western blot analysis using anti-Nef monoclonal antibody confirmed it. Conclusion: The purified Tat-Nef recombinant fusion protein will be used as an antigen for protein vaccine design against HIV infection.

  11. Male pheromone protein components activate female vomeronasal neurons in the salamander Plethodon shermani

    Directory of Open Access Journals (Sweden)

    Feldhoff Pamela W

    2006-03-01

    Full Text Available Abstract Background The mental gland pheromone of male Plethodon salamanders contains two main protein components: a 22 kDa protein named Plethodon Receptivity Factor (PRF and a 7 kDa protein named Plethodon Modulating Factor (PMF, respectively. Each protein component individually has opposing effects on female courtship behavior, with PRF shortening and PMF lengthening courtship. In this study, we test the hypothesis that PRF or PMF individually activate vomeronasal neurons. The agmatine-uptake technique was used to visualize chemosensory neurons that were activated by each protein component individually. Results Vomeronasal neurons exposed to agmatine in saline did not demonstrate significant labeling. However, a population of vomeronasal neurons was labeled following exposure to either PRF or PMF. When expressed as a percent of control level labeled cells, PRF labeled more neurons than did PMF. These percentages for PRF and PMF, added together, parallel the percentage of labeled vomeronasal neurons when females are exposed to the whole pheromone. Conclusion This study suggests that two specific populations of female vomeronasal neurons are responsible for responding to each of the two components of the male pheromone mixture. These two neural populations, therefore, could express different receptors which, in turn, transmit different information to the brain, thus accounting for the different female behavior elicited by each pheromone component.

  12. Hyperpolarization-activated current (In is reduced in hippocampal neurons from Gabra5-/- mice.

    Directory of Open Access Journals (Sweden)

    Robert P Bonin

    Full Text Available Changes in the expression of γ-aminobutyric acid type A (GABAA receptors can either drive or mediate homeostatic alterations in neuronal excitability. A homeostatic relationship between α5 subunit-containing GABAA (α5GABAA receptors that generate a tonic inhibitory conductance, and HCN channels that generate a hyperpolarization-activated cation current (Ih was recently described for cortical neurons, where a reduction in Ih was accompanied by a reciprocal increase in the expression of α5GABAA receptors resulting in the preservation of dendritosomatic synaptic function. Here, we report that in mice that lack the α5 subunit gene (Gabra5-/-, cultured embryonic hippocampal pyramidal neurons and ex vivo CA1 hippocampal neurons unexpectedly exhibited a decrease in Ih current density (by 40% and 28%, respectively, compared with neurons from wild-type (WT mice. The resting membrane potential and membrane hyperpolarization induced by blockade of Ih with ZD-7288 were similar in cultured WT and Gabra5-/- neurons. In contrast, membrane hyperpolarization measured after a train of action potentials was lower in Gabra5-/- neurons than in WT neurons. Also, membrane impedance measured in response to low frequency stimulation was greater in cultured Gabra5-/- neurons. Finally, the expression of HCN1 protein that generates Ih was reduced by 41% in the hippocampus of Gabra5-/- mice. These data indicate that loss of a tonic GABAergic inhibitory conductance was followed by a compensatory reduction in Ih. The results further suggest that the maintenance of resting membrane potential is preferentially maintained in mature and immature hippocampal neurons through the homeostatic co-regulation of structurally and biophysically distinct cation and anion channels.

  13. A light- and calcium-gated transcription factor for imaging and manipulating activated neurons.

    Science.gov (United States)

    Wang, Wenjing; Wildes, Craig P; Pattarabanjird, Tanyaporn; Sanchez, Mateo I; Glober, Gordon F; Matthews, Gillian A; Tye, Kay M; Ting, Alice Y

    2017-09-01

    Activity remodels neurons, altering their molecular, structural, and electrical characteristics. To enable the selective characterization and manipulation of these neurons, we present FLARE, an engineered transcription factor that drives expression of fluorescent proteins, opsins, and other genetically encoded tools only in the subset of neurons that experienced activity during a user-defined time window. FLARE senses the coincidence of elevated cytosolic calcium and externally applied blue light, which together produce translocation of a membrane-anchored transcription factor to the nucleus to drive expression of any transgene. In cultured rat neurons, FLARE gives a light-to-dark signal ratio of 120 and a high- to low-calcium signal ratio of 10 after 10 min of stimulation. Opsin expression permitted functional manipulation of FLARE-marked neurons. In adult mice, FLARE also gave light- and motor-activity-dependent transcription in the cortex. Due to its modular design, minute-scale temporal resolution, and minimal dark-state leak, FLARE should be useful for the study of activity-dependent processes in neurons and other cells that signal with calcium.

  14. Ultrafine carbon particles promote rotenone-induced dopamine neuronal loss through activating microglial NADPH oxidase

    International Nuclear Information System (INIS)

    Wang, Yinxi; Liu, Dan; Zhang, Huifeng; Wang, Yixin; Wei, Ling; Liu, Yutong; Liao, Jieying; Gao, Hui-Ming; Zhou, Hui

    2017-01-01

    Background: Atmospheric ultrafine particles (UFPs) and pesticide rotenone were considered as potential environmental risk factors for Parkinson's disease (PD). However, whether and how UFPs alone and in combination with rotenone affect the pathogenesis of PD remains largely unknown. Methods: Ultrafine carbon black (ufCB, a surrogate of UFPs) and rotenone were used individually or in combination to determine their roles in chronic dopaminergic (DA) loss in neuron-glia, and neuron-enriched, mix-glia cultures. Immunochemistry using antibody against tyrosine hydroxylase was performed to detect DA neuronal loss. Measurement of extracellular superoxide and intracellular reactive oxygen species (ROS) were performed to examine activation of NADPH oxidase. Genetic deletion and pharmacological inhibition of NADPH oxidase and MAC-1 receptor in microglia were employed to examine their role in DA neuronal loss triggered by ufCB and rotenone. Results: In rodent midbrain neuron-glia cultures, ufCB and rotenone alone caused neuronal death in a dose-dependent manner. In particularly, ufCB at doses of 50 and 100 μg/cm 2 induced significant loss of DA neurons. More importantly, nontoxic doses of ufCB (10 μg/cm 2 ) and rotenone (2 nM) induced synergistic toxicity to DA neurons. Microglial activation was essential in this process. Furthermore, superoxide production from microglial NADPH oxidase was critical in ufCB/rotenone-induced neurotoxicity. Studies in mix-glia cultures showed that ufCB treatment activated microglial NADPH oxidase to induce superoxide production. Firstly, ufCB enhanced the expression of NADPH oxidase subunits (gp91 phox , p47 phox and p40 phox ); secondly, ufCB was recognized by microglial surface MAC-1 receptor and consequently promoted rotenone-induced p47 phox and p67 phox translocation assembling active NADPH oxidase. Conclusion: ufCB and rotenone worked in synergy to activate NADPH oxidase in microglia, leading to oxidative damage to DA neurons. Our

  15. Ultrafine carbon particles promote rotenone-induced dopamine neuronal loss through activating microglial NADPH oxidase

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yinxi; Liu, Dan; Zhang, Huifeng; Wang, Yixin [Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, 100191 (China); Wei, Ling [Beijing Center for Physical & Chemical Analysis, Beijing 100089 (China); Liu, Yutong [School of Life Science, Beijing Normal University, Beijing 100875 (China); Liao, Jieying [Department of Translational Medicine, Xiamen Institute of Rare Earth Materials, Chinese Academy of Sciences, Xiamen 361024 (China); Gao, Hui-Ming [Model Animal Research Center of Nanjing University, Nanjing 211800 (China); Zhou, Hui, E-mail: hardhui@gmail.com [Department of Occupational and Environmental Health Sciences, School of Public Health, Peking University, 100191 (China)

    2017-05-01

    Background: Atmospheric ultrafine particles (UFPs) and pesticide rotenone were considered as potential environmental risk factors for Parkinson's disease (PD). However, whether and how UFPs alone and in combination with rotenone affect the pathogenesis of PD remains largely unknown. Methods: Ultrafine carbon black (ufCB, a surrogate of UFPs) and rotenone were used individually or in combination to determine their roles in chronic dopaminergic (DA) loss in neuron-glia, and neuron-enriched, mix-glia cultures. Immunochemistry using antibody against tyrosine hydroxylase was performed to detect DA neuronal loss. Measurement of extracellular superoxide and intracellular reactive oxygen species (ROS) were performed to examine activation of NADPH oxidase. Genetic deletion and pharmacological inhibition of NADPH oxidase and MAC-1 receptor in microglia were employed to examine their role in DA neuronal loss triggered by ufCB and rotenone. Results: In rodent midbrain neuron-glia cultures, ufCB and rotenone alone caused neuronal death in a dose-dependent manner. In particularly, ufCB at doses of 50 and 100 μg/cm{sup 2} induced significant loss of DA neurons. More importantly, nontoxic doses of ufCB (10 μg/cm{sup 2}) and rotenone (2 nM) induced synergistic toxicity to DA neurons. Microglial activation was essential in this process. Furthermore, superoxide production from microglial NADPH oxidase was critical in ufCB/rotenone-induced neurotoxicity. Studies in mix-glia cultures showed that ufCB treatment activated microglial NADPH oxidase to induce superoxide production. Firstly, ufCB enhanced the expression of NADPH oxidase subunits (gp91{sup phox}, p47{sup phox} and p40{sup phox}); secondly, ufCB was recognized by microglial surface MAC-1 receptor and consequently promoted rotenone-induced p47{sup phox} and p67{sup phox} translocation assembling active NADPH oxidase. Conclusion: ufCB and rotenone worked in synergy to activate NADPH oxidase in microglia, leading to

  16. Phosphoinositide-3-kinase activation controls synaptogenesis and spinogenesis in hippocampal neurons.

    Science.gov (United States)

    Cuesto, Germán; Enriquez-Barreto, Lilian; Caramés, Cristina; Cantarero, Marta; Gasull, Xavier; Sandi, Carmen; Ferrús, Alberto; Acebes, Ángel; Morales, Miguel

    2011-02-23

    The possibility of changing the number of synapses may be an important asset in the treatment of neurological diseases. In this context, the synaptogenic role of the phosphoinositide-3-kinase (PI3K) signaling cascade has been previously demonstrated in Drosophila. This study shows that treatment with a PI3K-activating transduction peptide is able to promote synaptogenesis and spinogenesis in primary cultures of rat hippocampal neurons, as well as in CA1 hippocampal neurons in vivo. In culture, the peptide increases synapse density independently of cell density, culture age, dendritic complexity, or synapse type. The induced synapses also increase neurotransmitter release from cultured neurons. The synaptogenic signaling pathway includes PI3K-Akt. Furthermore, the treatment is effective on adult neurons, where it induces spinogenesis and enhances the cognitive behavior of treated animals in a fear-conditioning assay. These findings demonstrate that functional synaptogenesis can be induced in mature mammalian brains through PI3K activation.

  17. Concentration-dependent activation of dopamine receptors differentially modulates GABA release onto orexin neurons.

    Science.gov (United States)

    Linehan, Victoria; Trask, Robert B; Briggs, Chantalle; Rowe, Todd M; Hirasawa, Michiru

    2015-08-01

    Dopamine (DA) and orexin neurons play important roles in reward and food intake. There are anatomical and functional connections between these two cell groups: orexin peptides stimulate DA neurons in the ventral tegmental area and DA inhibits orexin neurons in the hypothalamus. However, the cellular mechanisms underlying the action of DA on orexin neurons remain incompletely understood. Therefore, the effect of DA on inhibitory transmission to orexin neurons was investigated in rat brain slices using the whole-cell patch-clamp technique. We found that DA modulated the frequency of spontaneous and miniature IPSCs (mIPSCs) in a concentration-dependent bidirectional manner. Low (1 μM) and high (100 μM) concentrations of DA decreased and increased IPSC frequency, respectively. These effects did not accompany a change in mIPSC amplitude and persisted in the presence of G-protein signaling inhibitor GDPβS in the pipette, suggesting that DA acts presynaptically. The decrease in mIPSC frequency was mediated by D2 receptors whereas the increase required co-activation of D1 and D2 receptors and subsequent activation of phospholipase C. In summary, our results suggest that DA has complex effects on GABAergic transmission to orexin neurons, involving cooperation of multiple receptor subtypes. The direction of dopaminergic influence on orexin neurons is dependent on the level of DA in the hypothalamus. At low levels DA disinhibits orexin neurons whereas at high levels it facilitates GABA release, which may act as negative feedback to curb the excitatory orexinergic output to DA neurons. These mechanisms may have implications for consummatory and motivated behaviours. © 2015 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  18. GABAB-receptor activation alters the firing pattern of dopamine neurons in the rat substantia nigra.

    Science.gov (United States)

    Engberg, G; Kling-Petersen, T; Nissbrandt, H

    1993-11-01

    Previous electrophysiological experiments have emphasized the importance of the firing pattern for the functioning of midbrain dopamine (DA) neurons. In this regard, excitatory amino acid receptors appear to constitute an important modulatory control mechanism. In the present study, extracellular recording techniques were used to investigate the significance of GABAB-receptor activation for the firing properties of DA neurons in the substantia nigra (SN) in the rat. Intravenous administration of the GABAB-receptor agonist baclofen (1-16 mg/kg) was associated with a dose-dependent regularization of the firing pattern, concomitant with a reduction in burst firing. At higher doses (16-32 mg/kg), the firing rate of the DA neurons was dose-dependently decreased. Also, microiontophoretic application of baclofen regularized the firing pattern of nigral DA neurons, including a reduction of burst firing. Both the regularization of the firing pattern and inhibition of firing rate produced by systemic baclofen administration was antagonized by the GABAB-receptor antagonist CGP 35348 (200 mg/kg, i.v.). The GABAA-receptor agonist muscimol produced effects on the firing properties of DA neurons that were opposite to those observed following baclofen, i.e., an increase in firing rate accompanied by a decreased regularity. The NMDA receptor antagonist MK 801 (0.4-3.2 mg/kg, i.v.) produced a moderate, dose-dependent increase in the firing rate of the nigral DA neurons as well as a slightly regularized firing pattern. Pretreatment with MK 801 (3.2 mg/kg, i.v., 3-10 min) did neither promote nor prevent the regularization of the firing pattern or inhibition of firing rate on the nigral DA neurons produced by baclofen. The present results clearly show that GABAB-receptors can alter the firing pattern of nigral DA neurons, hereby counterbalancing the previously described ability of glutamate to induce burst firing activity on these neurons.

  19. (S)Pot on Mitochondria: Cannabinoids Disrupt Cellular Respiration to Limit Neuronal Activity.

    Science.gov (United States)

    Harkany, Tibor; Horvath, Tamas L

    2017-01-10

    Classical views posit G protein-coupled cannabinoid receptor 1s (CB1Rs) at the cell surface with cytosolic Giα-mediated signal transduction. Hebert-Chatelain et al. (2016) instead place CB 1 Rs at mitochondria limiting neuronal respiration by soluble adenylyl cyclase-dependent modulation of complex I activity. Thus, neuronal bioenergetics link to synaptic plasticity and, globally, learning and memory. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. An electronic implementation for Liao's chaotic delayed neuron model with non-monotonous activation function

    International Nuclear Information System (INIS)

    Duan Shukai; Liao Xiaofeng

    2007-01-01

    A new chaotic delayed neuron model with non-monotonously increasing transfer function, called as chaotic Liao's delayed neuron model, was recently reported and analyzed. An electronic implementation of this model is described in detail. At the same time, some methods in circuit design, especially for circuit with time delayed unit and non-monotonously increasing activation unit, are also considered carefully. We find that the dynamical behaviors of the designed circuits are closely similar to the results predicted by numerical experiments

  1. The Age of Enlightenment: Evolving Opportunities in Brain Research Through Optical Manipulation of Neuronal Activity

    OpenAIRE

    Jerome, Jason; Heck, Detlef H.

    2011-01-01

    Optical manipulation of neuronal activity has rapidly developed into the most powerful and widely used approach to study mechanisms related to neuronal connectivity over a range of scales. Since the early use of single site uncaging to map network connectivity, rapid technological development of light modulation techniques has added important new options, such as fast scanning photostimulation, massively parallel control of light stimuli, holographic uncaging, and two-photon stimulation techn...

  2. Acute activation of GLP-1-expressing neurons promotes glucose homeostasis and insulin sensitivity

    OpenAIRE

    Xuemei Shi; Shaji Chacko; Feng Li; Depei Li; Douglas Burrin; Lawrence Chan; Xinfu Guan

    2017-01-01

    Objective: Glucagon-like peptides are co-released from enteroendocrine L cells in the gut and preproglucagon (PPG) neurons in the brainstem. PPG-derived GLP-1/2 are probably key neuroendocrine signals for the control of energy balance and glucose homeostasis. The objective of this study was to determine whether activation of PPG neurons per se modulates glucose homeostasis and insulin sensitivity in vivo. Methods: We generated glucagon (Gcg) promoter-driven Cre transgenic mice and injected...

  3. Neuron to astrocyte communication via cannabinoid receptors is necessary for sustained epileptiform activity in rat hippocampus.

    OpenAIRE

    Coiret Guyllaume; Ster Jeanne; Grewe Benjamin; Wendling Fabrice; Helmchen Fritjof; Gerber Urs; Benquet Pascal

    2012-01-01

    International audience; Astrocytes are integral functional components of synapses, regulating transmission and plasticity. They have also been implicated in the pathogenesis of epilepsy, although their precise roles have not been comprehensively characterized. Astrocytes integrate activity from neighboring synapses by responding to neuronally released neurotransmitters such as glutamate and ATP. Strong activation of astrocytes mediated by these neurotransmitters can promote seizure-like activ...

  4. Activation of Six1 Expression in Vertebrate Sensory Neurons.

    Directory of Open Access Journals (Sweden)

    Shigeru Sato

    Full Text Available SIX1 homeodomain protein is one of the essential key regulators of sensory organ development. Six1-deficient mice lack the olfactory epithelium, vomeronasal organs, cochlea, vestibule and vestibuloacoustic ganglion, and also show poor neural differentiation in the distal part of the cranial ganglia. Simultaneous loss of both Six1 and Six4 leads to additional abnormalities such as small trigeminal ganglion and abnormal dorsal root ganglia (DRG. The aim of this study was to understand the molecular mechanism that controls Six1 expression in sensory organs, particularly in the trigeminal ganglion and DRG. To this end, we focused on the sensory ganglia-specific Six1 enhancer (Six1-8 conserved between chick and mouse. In vivo reporter assays using both animals identified an important core region comprising binding consensus sequences for several transcription factors including nuclear hormone receptors, TCF/LEF, SMAD, POU homeodomain and basic-helix-loop-helix proteins. The results provided information on upstream factors and signals potentially relevant to Six1 regulation in sensory neurons. We also report the establishment of a new transgenic mouse line (mSix1-8-NLSCre that expresses Cre recombinase under the control of mouse Six1-8. Cre-mediated recombination was detected specifically in ISL1/2-positive sensory neurons of Six1-positive cranial sensory ganglia and DRG. The unique features of the mSix1-8-NLSCre line are the absence of Cre-mediated recombination in SOX10-positive glial cells and central nervous system and ability to induce recombination in a subset of neurons derived from the olfactory placode/epithelium. This mouse model can be potentially used to advance research on sensory development.

  5. Cellular activation of hypothalamic hypocretin/orexin neurons facilitates short-term spatial memory in mice.

    Science.gov (United States)

    Aitta-Aho, Teemu; Pappa, Elpiniki; Burdakov, Denis; Apergis-Schoute, John

    2016-12-01

    The hypothalamic hypocretin/orexin (HO) system holds a central role in the regulation of several physiological functions critical for food-seeking behavior including mnemonic processes for effective foraging behavior. It is unclear however whether physiological increases in HO neuronal activity can support such processes. Using a designer rM3Ds receptor activation approach increasing HO neuronal activity resulted in improved short-term memory for novel locations. When tested on a non-spatial novelty object recognition task no significant difference was detected between groups indicating that hypothalamic HO neuronal activation can selectively facilitate short-term spatial memory for potentially supporting memory for locations during active exploration. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. Organization of Functional Long-Range Circuits Controlling the Activity of Serotonergic Neurons in the Dorsal Raphe Nucleus

    Directory of Open Access Journals (Sweden)

    Li Zhou

    2017-03-01

    Full Text Available Serotonergic neurons play key roles in various biological processes. However, circuit mechanisms underlying tight control of serotonergic neurons remain largely unknown. Here, we systematically investigated the organization of long-range synaptic inputs to serotonergic neurons and GABAergic neurons in the dorsal raphe nucleus (DRN of mice with a combination of viral tracing, slice electrophysiological, and optogenetic techniques. We found that DRN serotonergic neurons and GABAergic neurons receive largely comparable synaptic inputs from six major upstream brain areas. Upon further analysis of the fine functional circuit structures, we found both bilateral and ipsilateral patterns of topographic connectivity in the DRN for the axons from different inputs. Moreover, the upstream brain areas were found to bidirectionally control the activity of DRN serotonergic neurons by recruiting feedforward inhibition or via a push-pull mechanism. Our study provides a framework for further deciphering the functional roles of long-range circuits controlling the activity of serotonergic neurons in the DRN.

  7. Response of Electrical Activity in an Improved Neuron Model under Electromagnetic Radiation and Noise.

    Science.gov (United States)

    Zhan, Feibiao; Liu, Shenquan

    2017-01-01

    Electrical activities are ubiquitous neuronal bioelectric phenomena, which have many different modes to encode the expression of biological information, and constitute the whole process of signal propagation between neurons. Therefore, we focus on the electrical activities of neurons, which is also causing widespread concern among neuroscientists. In this paper, we mainly investigate the electrical activities of the Morris-Lecar (M-L) model with electromagnetic radiation or Gaussian white noise, which can restore the authenticity of neurons in realistic neural network. First, we explore dynamical response of the whole system with electromagnetic induction (EMI) and Gaussian white noise. We find that there are slight differences in the discharge behaviors via comparing the response of original system with that of improved system, and electromagnetic induction can transform bursting or spiking state to quiescent state and vice versa. Furthermore, we research bursting transition mode and the corresponding periodic solution mechanism for the isolated neuron model with electromagnetic induction by using one-parameter and bi-parameters bifurcation analysis. Finally, we analyze the effects of Gaussian white noise on the original system and coupled system, which is conducive to understand the actual discharge properties of realistic neurons.

  8. Response of Electrical Activity in an Improved Neuron Model under Electromagnetic Radiation and Noise

    Directory of Open Access Journals (Sweden)

    Feibiao Zhan

    2017-11-01

    Full Text Available Electrical activities are ubiquitous neuronal bioelectric phenomena, which have many different modes to encode the expression of biological information, and constitute the whole process of signal propagation between neurons. Therefore, we focus on the electrical activities of neurons, which is also causing widespread concern among neuroscientists. In this paper, we mainly investigate the electrical activities of the Morris-Lecar (M-L model with electromagnetic radiation or Gaussian white noise, which can restore the authenticity of neurons in realistic neural network. First, we explore dynamical response of the whole system with electromagnetic induction (EMI and Gaussian white noise. We find that there are slight differences in the discharge behaviors via comparing the response of original system with that of improved system, and electromagnetic induction can transform bursting or spiking state to quiescent state and vice versa. Furthermore, we research bursting transition mode and the corresponding periodic solution mechanism for the isolated neuron model with electromagnetic induction by using one-parameter and bi-parameters bifurcation analysis. Finally, we analyze the effects of Gaussian white noise on the original system and coupled system, which is conducive to understand the actual discharge properties of realistic neurons.

  9. Plasticity of Neuron-Glial Transmission: Equipping Glia for Long-Term Integration of Network Activity

    Directory of Open Access Journals (Sweden)

    Wayne Croft

    2015-01-01

    Full Text Available The capacity of synaptic networks to express activity-dependent changes in strength and connectivity is essential for learning and memory processes. In recent years, glial cells (most notably astrocytes have been recognized as active participants in the modulation of synaptic transmission and synaptic plasticity, implicating these electrically nonexcitable cells in information processing in the brain. While the concept of bidirectional communication between neurons and glia and the mechanisms by which gliotransmission can modulate neuronal function are well established, less attention has been focussed on the computational potential of neuron-glial transmission itself. In particular, whether neuron-glial transmission is itself subject to activity-dependent plasticity and what the computational properties of such plasticity might be has not been explored in detail. In this review, we summarize current examples of plasticity in neuron-glial transmission, in many brain regions and neurotransmitter pathways. We argue that induction of glial plasticity typically requires repetitive neuronal firing over long time periods (minutes-hours rather than the short-lived, stereotyped trigger typical of canonical long-term potentiation. We speculate that this equips glia with a mechanism for monitoring average firing rates in the synaptic network, which is suited to the longer term roles proposed for astrocytes in neurophysiology.

  10. Apelin-13 enhances arcuate POMC neuron activity via inhibiting M-current.

    Directory of Open Access Journals (Sweden)

    Dong Kun Lee

    Full Text Available The hypothalamus is a key element of the neural circuits that control energy homeostasis. Specific neuronal populations within the hypothalamus are sensitive to a variety of homeostatic indicators such as circulating nutrient levels and hormones that signal circulating glucose and body fat content. Central injection of apelin secreted by adipose tissues regulates feeding and glucose homeostasis. However, the precise neuronal populations and cellular mechanisms involved in these physiological processes remain unclear. Here we examine the electrophysiological impact of apelin-13 on proopiomelanocortin (POMC neuron activity. Approximately half of POMC neurons examined respond to apelin-13. Apelin-13 causes a dose-dependent depolarization. This effect is abolished by the apelin (APJ receptor antagonist. POMC neurons from animals pre-treated with pertussis toxin still respond to apelin, whereas the Gβγ signaling inhibitor gallein blocks apelin-mediated depolarization. In addition, the effect of apelin is inhibited by the phospholipase C and protein kinase inhibitors. Furthermore, single-cell qPCR analysis shows that POMC neurons express the APJ receptor, PLC-β isoforms, and KCNQ subunits (2, 3 and 5 which contribute to M-type current. Apelin-13 inhibits M-current that is blocked by the KCNQ channel inhibitor. Therefore, our present data indicate that apelin activates APJ receptors, and the resultant dissociation of the Gαq heterotrimer triggers a Gβγ-dependent activation of PLC-β signaling that inhibits M-current.

  11. Intermittent but not sustained hypoxia activates orexin-containing neurons in mice.

    Science.gov (United States)

    Yamaguchi, Keiji; Futatsuki, Takahiro; Ushikai, Jumpei; Kuroki, Chiharu; Minami, Toshiaki; Kakihana, Yasuyuki; Kuwaki, Tomoyuki

    2015-01-15

    Hypothalamic orexin-containing neurons are activated by CO2 and contribute to hypercapnic ventilatory activation. However, their role in oxygen-related regulation of breathing is not well defined. In this study, we examined whether an experimental model mimicking apnea-induced repetitive hypoxemia (intermittent hypoxia [IH]) activates orexin-containing neurons. Mice were exposed to IH (5×5min at 10% O2), intermittent hyperoxia (IO; 5×5min at 50% O2), sustained hypoxia (SH; 25min at 10% O2), or sham stimulation. Their brains were examined using double immunohistochemical staining for orexin and c-Fos. The results indicated that IH (25.8±3.0%), but not SH (9.0±1.5%) activated orexin-containing neurons when compared to IO (5.5±0.6%) and sham stimulation (5.9±1.4%). These results correlate with those of our previous work showing that IH-induced respiratory long-term facilitation is dependent on orexin-containing neurons. Taken together, orexin contributes to repetitive hypoxia-induced respiratory activation and the hypoxic activation of orexin-containing neurons is pattern dependent. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Brain innate immunity regulates hypothalamic arcuate neuronal activity and feeding behavior.

    Science.gov (United States)

    Reis, Wagner L; Yi, Chun-Xia; Gao, Yuanqing; Tschöp, Mathias H; Stern, Javier E

    2015-04-01

    Hypothalamic inflammation, involving microglia activation in the arcuate nucleus (ARC), is proposed as a novel underlying mechanism in obesity, insulin and leptin resistance. However, whether activated microglia affects ARC neuronal activity, and consequently basal and hormonal-induced food intake, is unknown. We show that lipopolysaccharide, an agonist of the toll-like receptor-4 (TLR4), which we found to be expressed in ARC microglia, inhibited the firing activity of the majority of orexigenic agouti gene-related protein/neuropeptide Y neurons, whereas it increased the activity of the majority of anorexigenic proopiomelanocortin neurons. Lipopolysaccharide effects in agouti gene-related protein/neuropeptide Y (but not in proopiomelanocortin) neurons were occluded by inhibiting microglia function or by blocking TLR4 receptors. Finally, we report that inhibition of hypothalamic microglia altered basal food intake, also preventing central orexigenic responses to ghrelin. Our studies support a major role for a TLR4-mediated microglia signaling pathway in the control of ARC neuronal activity and feeding behavior.

  13. Response of Cultured Neuronal Network Activity After High-Intensity Power Frequency Magnetic Field Exposure

    Directory of Open Access Journals (Sweden)

    Atsushi Saito

    2018-03-01

    Full Text Available High-intensity and low frequency (1–100 kHz time-varying electromagnetic fields stimulate the human body through excitation of the nervous system. In power frequency range (50/60 Hz, a frequency-dependent threshold of the external electric field-induced neuronal modulation in cultured neuronal networks was used as one of the biological indicator in international guidelines; however, the threshold of the magnetic field-induced neuronal modulation has not been elucidated. In this study, we exposed rat brain-derived neuronal networks to a high-intensity power frequency magnetic field (hPF-MF, and evaluated the modulation of synchronized bursting activity using a multi-electrode array (MEA-based extracellular recording technique. As a result of short-term hPF-MF exposure (50–400 mT root-mean-square (rms, 50 Hz, sinusoidal wave, 6 s, the synchronized bursting activity was increased in the 400 mT-exposed group. On the other hand, no change was observed in the 50–200 mT-exposed groups. In order to clarify the mechanisms of the 400 mT hPF-MF exposure-induced neuronal response, we evaluated it after blocking inhibitory synapses using bicuculline methiodide (BMI; subsequently, increase in bursting activity was observed with BMI application, and the response of 400 mT hPF-MF exposure disappeared. Therefore, it was suggested that the response of hPF-MF exposure was involved in the inhibitory input. Next, we screened the inhibitory pacemaker-like neuronal activity which showed autonomous 4–10 Hz firing with CNQX and D-AP5 application, and it was confirmed that the activity was reduced after 400 mT hPF-MF exposure. Comparison of these experimental results with estimated values of the induced electric field (E-field in the culture medium revealed that the change in synchronized bursting activity occurred over 0.3 V/m, which was equivalent to the findings of a previous study that used the external electric fields. In addition, the results suggested that

  14. Artificial Induction of Associative Olfactory Memory by Optogenetic and Thermogenetic Activation of Olfactory Sensory Neurons and Octopaminergic Neurons in Drosophila Larvae.

    Science.gov (United States)

    Honda, Takato; Lee, Chi-Yu; Honjo, Ken; Furukubo-Tokunaga, Katsuo

    2016-01-01

    The larval brain of Drosophila melanogaster provides an excellent system for the study of the neurocircuitry mechanism of memory. Recent development of neurogenetic techniques in fruit flies enables manipulations of neuronal activities in freely behaving animals. This protocol describes detailed steps for artificial induction of olfactory associative memory in Drosophila larvae. In this protocol, the natural reward signal is substituted by thermogenetic activation of octopaminergic neurons in the brain. In parallel, the odor signal is substituted by optogenetic activation of a specific class of olfactory receptor neurons. Association of reward and odor stimuli is achieved with the concomitant application of blue light and heat that leads to activation of both sets of neurons in living transgenic larvae. Given its operational simplicity and robustness, this method could be utilized to further our knowledge on the neurocircuitry mechanism of memory in the fly brain.

  15. Scaling of Brain Metabolism with a Fixed Energy Budget per Neuron: Implications for Neuronal Activity, Plasticity and Evolution

    OpenAIRE

    Herculano-Houzel, Suzana

    2011-01-01

    It is usually considered that larger brains have larger neurons, which consume more energy individually, and are therefore accompanied by a larger number of glial cells per neuron. These notions, however, have never been tested. Based on glucose and oxygen metabolic rates in awake animals and their recently determined numbers of neurons, here I show that, contrary to the expected, the estimated glucose use per neuron is remarkably constant, varying only by 40% across the six species of rodent...

  16. Silibinin activates AMP-activated protein kinase to protect neuronal cells from oxygen and glucose deprivation-re-oxygenation.

    Science.gov (United States)

    Xie, Zhi; Ding, Sheng-quan; Shen, Ya-fang

    2014-11-14

    In this study, we explored the cytoprotective potential of silibinin against oxygen-glucose deprivation (OGD)-induced neuronal cell damages, and studied underling mechanisms. In vitro model of ischemic stroke was created by keeping neuronal cells (SH-SY5Y cells and primary mouse cortical neurons) in an OGD condition followed by re-oxygenation. Pre-treatment of silibinin significantly inhibited OGD/re-oxygenation-induced necrosis and apoptosis of neuronal cells. OGD/re-oxygenation-induced reactive oxygen species (ROS) production and mitochondrial membrane potential (MMP) reduction were also inhibited by silibinin. At the molecular level, silibinin treatment in SH-SY5Y cells and primary cortical neurons led to significant AMP-activated protein kinase (AMPK) signaling activation, detected by phosphorylations of AMPKα1, its upstream kinase liver kinase B1 (LKB1) and the downstream target acetyl-CoA Carboxylase (ACC). Pharmacological inhibition or genetic depletion of AMPK alleviated the neuroprotective ability of silibinin against OGD/re-oxygenation. Further, ROS scavenging ability by silibinin was abolished with AMPK inhibition or silencing. While A-769662, the AMPK activator, mimicked silibinin actions and suppressed ROS production and neuronal cell death following OGD/re-oxygenation. Together, these results show that silibinin-mediated neuroprotection requires activation of AMPK signaling. Copyright © 2014 Elsevier Inc. All rights reserved.

  17. Correlations between histology and neuronal activity recorded by microelectrodes implanted chronically in the cerebral cortex

    Science.gov (United States)

    McCreery, Douglas; Cogan, Stuart; Kane, Sheryl; Pikov, Victor

    2016-06-01

    Objective. To quantify relations between the neuronal activity recorded with chronically-implanted intracortical microelectrodes and the histology of the surrounding tissue, using radial distance from the tip sites and time after array implantation as parameters. Approach. ‘Utah’-type intracortical microelectrode arrays were implanted into cats’ sensorimotor cortex for 275-364 days. The brain tissue around the implants was immuno-stained for the neuronal marker NeuN and for the astrocyte marker GFAP. Pearson’s product-moment correlations were used to quantify the relations between these markers and the amplitudes of the recorded neuronal action potentials (APs) and their signal-to-noise ratios (S/N). Main results. S/N was more stable over post-implant time than was AP amplitude, but its increased correlation with neuronal density after many months indicates ongoing loss of neurons around the microelectrodes. S/N was correlated with neuron density out to at least 140 μm from the microelectrodes, while AP amplitude was correlated with neuron density and GFAP density within ˜80 μm. Correlations between AP amplitude and histology markers (GFAP and NeuN density) were strongest immediately after implantation, while correlation between the neuron density and S/N was strongest near the time the animals were sacrificed. Unlike AP amplitude, there was no significant correlation between S/N and density of GFAP around the tip sites. Significance. Our findings indicate an evolving interaction between changes in the tissue surrounding the microelectrodes and the microelectrode’s electrical properties. Ongoing loss of neurons around recording microelectrodes, and the interactions between their delayed electrical deterioration and early tissue scarring around the tips appear to pose the greatest threats to the microelectrodes’ long-term functionality.

  18. Spatio-temporal specialization of GABAergic septo-hippocampal neurons for rhythmic network activity.

    Science.gov (United States)

    Unal, Gunes; Crump, Michael G; Viney, Tim J; Éltes, Tímea; Katona, Linda; Klausberger, Thomas; Somogyi, Peter

    2018-03-03

    Medial septal GABAergic neurons of the basal forebrain innervate the hippocampus and related cortical areas, contributing to the coordination of network activity, such as theta oscillations and sharp wave-ripple events, via a preferential innervation of GABAergic interneurons. Individual medial septal neurons display diverse activity patterns, which may be related to their termination in different cortical areas and/or to the different types of innervated interneurons. To test these hypotheses, we extracellularly recorded and juxtacellularly labeled single medial septal neurons in anesthetized rats in vivo during hippocampal theta and ripple oscillations, traced their axons to distant cortical target areas, and analyzed their postsynaptic interneurons. Medial septal GABAergic neurons exhibiting different hippocampal theta phase preferences and/or sharp wave-ripple related activity terminated in restricted hippocampal regions, and selectively targeted a limited number of interneuron types, as established on the basis of molecular markers. We demonstrate the preferential innervation of bistratified cells in CA1 and of basket cells in CA3 by individual axons. One group of septal neurons was suppressed during sharp wave-ripples, maintained their firing rate across theta and non-theta network states and mainly fired along the descending phase of CA1 theta oscillations. In contrast, neurons that were active during sharp wave-ripples increased their firing significantly during "theta" compared to "non-theta" states, with most firing during the ascending phase of theta oscillations. These results demonstrate that specialized septal GABAergic neurons contribute to the coordination of network activity through parallel, target area- and cell type-selective projections to the hippocampus.

  19. Die TAT-Z as voorspeller vir prestasiemotivering

    Directory of Open Access Journals (Sweden)

    F. V. N. Cilliers

    1979-11-01

    Die gebruik van die TAT-Z, 'n projeksietoets vir Swartmans, word ondersoek om prestasiemotivering veral tydens die indiensnemingsituasie te voorspel. Positiewe resultate is op 3 van die 10 kaarte (nrs. 4, 6 en 9 van die TAT-Z verkry. Aanbevelings word gemaak aangaande die aanpassing van hierdie projeksietoets ten einde meer inligting oor prestasiemotivering, bloot te lê.

  20. Estimation of the neuronal activation using fMRI data: An observer-based approach

    KAUST Repository

    Laleg-Kirati, Taous-Meriem

    2013-06-01

    This paper deals with the estimation of the neuronal activation and some unmeasured physiological information using the Blood Oxygenation Level Dependent (BOLD) signal measured using functional Magnetic Resonance Imaging (fMRI). We propose to use an observer-based approach applied to the balloon hemodynamic model. The latter describes the relation between the neural activity and the BOLD signal. The balloon model can be expressed in a nonlinear state-space representation where the states, the parameters and the input (neuronal activation), are unknown. This study focuses only on the estimation of the hidden states and the neuronal activation. The model is first linearized around the equilibrium and an observer is applied to this linearized version. Numerical results performed on synthetic data are presented.

  1. FlyMAD: rapid thermogenetic control of neuronal activity in freely walking Drosophila.

    Science.gov (United States)

    Bath, Daniel E; Stowers, John R; Hörmann, Dorothea; Poehlmann, Andreas; Dickson, Barry J; Straw, Andrew D

    2014-07-01

    Rapidly and selectively modulating the activity of defined neurons in unrestrained animals is a powerful approach in investigating the circuit mechanisms that shape behavior. In Drosophila melanogaster, temperature-sensitive silencers and activators are widely used to control the activities of genetically defined neuronal cell types. A limitation of these thermogenetic approaches, however, has been their poor temporal resolution. Here we introduce FlyMAD (the fly mind-altering device), which allows thermogenetic silencing or activation within seconds or even fractions of a second. Using computer vision, FlyMAD targets an infrared laser to freely walking flies. As a proof of principle, we demonstrated the rapid silencing and activation of neurons involved in locomotion, vision and courtship. The spatial resolution of the focused beam enabled preferential targeting of neurons in the brain or ventral nerve cord. Moreover, the high temporal resolution of FlyMAD allowed us to discover distinct timing relationships for two neuronal cell types previously linked to courtship song.

  2. Effects of activated ACM on expression of signal transducers in cerebral cortical neurons of rats.

    Science.gov (United States)

    Wang, Xiaojing; Li, Zhengli; Zhu, Changgeng; Li, Zhongyu

    2007-06-01

    To explore the roles of astrocytes in the epileptogenesis, astrocytes and neurons were isolated, purified and cultured in vitro from cerebral cortex of rats. The astrocytes were activated by ciliary neurotrophic factor (CNTF) and astrocytic conditioned medium (ACM) was collected to treat neurons for 4, 8 and 12 h. By using Western blot, the expression of calmodulin dependent protein kinase II (CaMK II), inducible nitric oxide synthase (iNOS) and adenylate cyclase (AC) was detected in neurons. The results showed that the expression of CaMK II, iNOS and AC was increased significantly in the neurons treated with ACM from 4 h to 12 h (PACM and such signal pathways as NOS-NO-cGMP, Ca2+/CaM-CaMK II and AC-cAMP-PKA might take part in the signal transduction of epileptogenesis.

  3. Neuron activity in rat hippocampus and motor cortex during discrimination reversal.

    Science.gov (United States)

    Disterhoft, J F; Segal, M

    1978-01-01

    Chronic unit activity and gross movement were recorded from rats during two discrimination reversals in a classical appetitive conditioning situation. The anticipatory movement decreased in response to the former CS+ tone and increased to the previous CS- tone after each reversal. Hippocampus and motor cortex were differently related to these two kinds of behavioral change. Response rates of hippocampal neurons were more closely related to the increased movement response to the former CS- which now signaled food. Motor cortex neuron responses were more closely correlated with the decrease in movement responses to the former CS+ which became neutral after the reversal. It appeared that hippocampal neurons could have been involved in one cognitive aspect of the situation, motor cortex neurons in another. The data were related to current functional concepts of these brain regions.

  4. Glucose level determines excitatory or inhibitory effects of adiponectin on arcuate POMC neuron activity and feeding.

    Science.gov (United States)

    Suyama, Shigetomo; Maekawa, Fumihiko; Maejima, Yuko; Kubota, Naoto; Kadowaki, Takashi; Yada, Toshihiko

    2016-08-09

    Adiponectin regulates glucose and lipid metabolism, acting against metabolic syndrome and atherosclerosis. Accumulating evidence suggest that adiponectin acts on the brain including hypothalamic arcuate nucleus (ARC), where proopiomelanocortin (POMC) neurons play key roles in feeding regulation. Several studies have examined intracerebroventricular (ICV) injection of adiponectin and reported opposite effects, increase or decrease of food intake. These reports used different nutritional states. The present study aimed to clarify whether adiponectin exerts distinct effects on food intake and ARC POMC neurons depending on the glucose concentration. Adiponectin was ICV injected with or without glucose for feeding experiments and administered to ARC slices with high or low glucose for patch clamp experiments. We found that adiponectin at high glucose inhibited POMC neurons and increased food intake while at low glucose it exerted opposite effects. The results demonstrate that glucose level determines excitatory or inhibitory effects of adiponectin on arcuate POMC neuron activity and feeding.

  5. Activation of Brainstem Pro-opiomelanocortin Neurons Produces Opioidergic Analgesia, Bradycardia and Bradypnoea.

    Science.gov (United States)

    Cerritelli, Serena; Hirschberg, Stefan; Hill, Rob; Balthasar, Nina; Pickering, Anthony E

    2016-01-01

    Opioids are widely used medicinally as analgesics and abused for hedonic effects, actions that are each complicated by substantial risks such as cardiorespiratory depression. These drugs mimic peptides such as β-endorphin, which has a key role in endogenous analgesia. The β-endorphin in the central nervous system originates from pro-opiomelanocortin (POMC) neurons in the arcuate nucleus and nucleus of the solitary tract (NTS). Relatively little is known about the NTSPOMC neurons but their position within the sensory nucleus of the vagus led us to test the hypothesis that they play a role in modulation of cardiorespiratory and nociceptive control. The NTSPOMC neurons were targeted using viral vectors in a POMC-Cre mouse line to express either opto-genetic (channelrhodopsin-2) or chemo-genetic (Pharmacologically Selective Actuator Modules). Opto-genetic activation of the NTSPOMC neurons in the working heart brainstem preparation (n = 21) evoked a reliable, titratable and time-locked respiratory inhibition (120% increase in inter-breath interval) with a bradycardia (125±26 beats per minute) and augmented respiratory sinus arrhythmia (58% increase). Chemo-genetic activation of NTSPOMC neurons in vivo was anti-nociceptive in the tail flick assay (latency increased by 126±65%, pneurons were found to project to key brainstem structures involved in cardiorespiratory control (nucleus ambiguus and ventral respiratory group) and endogenous analgesia (periaqueductal gray and midline raphe). Thus the NTSPOMC neurons may be capable of tuning behaviour by an opioidergic modulation of nociceptive, respiratory and cardiac control.

  6. p62 modulates Akt activity via association with PKCζ in neuronal survival and differentiation

    International Nuclear Information System (INIS)

    Joung, Insil; Kim, Hak Jae; Kwon, Yunhee Kim

    2005-01-01

    p62 is a ubiquitously expressed phosphoprotein that interacts with a number of signaling molecules and a major component of neurofibrillary tangles in the brain of Alzheimer's disease patients. It has been implicated in important cellular functions such as cell proliferation and anti-apoptotic pathways. In this study, we have addressed the potential role of p62 during neuronal differentiation and survival using HiB5, a rat neuronal progenitor cell. We generated a recombinant adenovirus encoding T7-epitope tagged p62 to reliably transfer p62 cDNA into the neuronal cells. The results show that an overexpression of p62 led not only to neuronal differentiation, but also to decreased cell death induced by serum withdrawal in HiB5 cells. In this process p62-dependent Akt phosphorylation occurred via the release of Akt from PKCζ by association of p62 and PKCζ, which is known as a negative regulator of Akt activation. These findings indicate that p62 facilitates cell survival through novel signaling cascades that result in Akt activation. Furthermore, we found that p62 expression was induced during neuronal differentiation. Taken together, the data suggest p62 is a regulator of neuronal cell survival and differentiation

  7. Mirror neuron activity associated with social impairments but not age in autism spectrum disorder.

    Science.gov (United States)

    Enticott, Peter G; Kennedy, Hayley A; Rinehart, Nicole J; Tonge, Bruce J; Bradshaw, John L; Taffe, John R; Daskalakis, Zafiris J; Fitzgerald, Paul B

    2012-03-01

    The neurobiology of autism spectrum disorder (ASD) is not particularly well understood, and biomedical treatment approaches are therefore extremely limited. A prominent explanatory model suggests that social-relating symptoms may arise from dysfunction within the mirror neuron system, while a recent neuroimaging study suggests that these impairments in ASD might reduce with age. Participants with autism spectrum disorder (i.e., DSM-IV autistic disorder or Asperger's disorder) (n = 34) and matched control subjects (n = 36) completed a transcranial magnetic stimulation study in which corticospinal excitability was assessed during the observation of hand gestures. Regression analyses revealed that the ASD group presented with significantly reduced corticospinal excitability during the observation of a transitive hand gesture (relative to observation of a static hand) (p mirror neuron system activity within ventral premotor cortex/inferior frontal gyrus. Among the ASD group, there was also a negative association between putative mirror neuron activity and self-reported social-relating impairments, but there was no indication that mirror neuron impairments in ASD decrease with age. These data provide general support for the mirror neuron hypothesis of autism; researchers now must clarify the precise functional significance of mirror neurons to truly understand their role in the neuropathophysiology of ASD and to determine whether they should be used as targets for the treatment of ASD.

  8. Neuronal activity rapidly induces transcription of the CREB-regulated microRNA-132, in vivo

    DEFF Research Database (Denmark)

    Nudelman, Aaron Samuel; DiRocco, Derek P; Lambert, Talley J

    2010-01-01

    Activity-dependent changes in gene-expression are believed to underlie the molecular representation of memory. In this study, we report that in vivo activation of neurons rapidly induces the CREB-regulated microRNA miR-132. To determine if production of miR-132 is regulated by neuronal activity its......, olfactory bulb, and striatum by contextual fear conditioning, odor-exposure, and cocaine-injection, respectively, also increased pri-miR-132. Induction kinetics of pri-miR-132 were monitored and found to parallel those of immediate early genes, peaking at 45 min and returning to basal levels within 2 h...

  9. ACETYL-L-CARNITINE AFFECTS THE ELECTRICAL ACTIVITY OF MECHANOSENSORY NEURONS IN HIRUDO MEDICINALIS GANGLIA

    Directory of Open Access Journals (Sweden)

    Giovanna Traina

    2017-04-01

    Full Text Available Was previously discovered that in the leech Hirudo medicinalis, acetyl-l-carnitine (ALC affects forms of non-associative learning, such as sensitization and dishabituation, due to nociceptive stimulation of the dorsal skin in the swim induction behavioural paradigm, likely through modulating the activity of the mechanosensory tactile (T neurons, which initiate swimming. Since was found that ALC impaired sensitization and dishabituation, both of which are mediated by the neurotransmitter serotonin, the present study analyzed how ALC may interfere with the sensitizing response. Was already found that ALC reduced the activity of nociceptive (N neurons, which modulate T cell activity through serotonergic mediation.

  10. Optogenetic stimulation of locus ceruleus neurons augments inhibitory transmission to parasympathetic cardiac vagal neurons via activation of brainstem α1 and β1 receptors.

    Science.gov (United States)

    Wang, Xin; Piñol, Ramón A; Byrne, Peter; Mendelowitz, David

    2014-04-30

    Locus ceruleus (LC) noradrenergic neurons are critical in generating alertness. In addition to inducing cortical arousal, the LC also orchestrates changes in accompanying autonomic system function that compliments increased attention, such as during stress, excitation, and/or exposure to averse or novel stimuli. Although the association between arousal and increased heart rate is well accepted, the neurobiological link between the LC and parasympathetic neurons that control heart rate has not been identified. In this study, we test directly whether activation of noradrenergic neurons in the LC influences brainstem parasympathetic cardiac vagal neurons (CVNs). CVNs were identified in transgenic mice that express channel-rhodopsin-2 (ChR2) in LC tyrosine hydroxylase neurons. Photoactivation evoked a rapid depolarization, increased firing, and excitatory inward currents in ChR2-expressing neurons in the LC. Photostimulation of LC neurons did not alter excitatory currents, but increased inhibitory neurotransmission to CVNs. Optogenetic activation of LC neurons increased the frequency of isolated glycinergic IPSCs by 27 ± 8% (p = 0.003, n = 26) and augmented GABAergic IPSCs in CVNs by 21 ± 5% (p = 0.001, n = 26). Inhibiting α1, but not α2, receptors blocked the evoked responses. Inhibiting β1 receptors prevented the increase in glycinergic, but not GABAergic, IPSCs in CVNs. This study demonstrates LC noradrenergic neurons inhibit the brainstem CVNs that generate parasympathetic activity to the heart. This inhibition of CVNs would increase heart rate and risks associated with tachycardia. The receptors activated within this pathway, α1 and/or β1 receptors, are targets for clinically prescribed antagonists that promote slower, cardioprotective heart rates during heightened vigilant states.

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

    Directory of Open Access Journals (Sweden)

    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.

  12. Activation of synaptic and extrasynaptic glycine receptors by taurine in preoptic hypothalamic neurons.

    Science.gov (United States)

    Bhattarai, Janardhan Prasad; Park, Soo Joung; Chun, Sang Woo; Cho, Dong Hyu; Han, Seong Kyu

    2015-11-03

    Taurine is an essential amino-sulfonic acid having a fundamental function in the brain, participating in both cell volume regulation and neurotransmission. Using a whole cell voltage patch clamp technique, the taurine-activated neurotransmitter receptors in the preoptic hypothalamic area (PHA) neurons were investigated. In the first set of experiments, different concentrations of taurine were applied on PHA neurons. Taurine-induced responses were concentration-dependent. Taurine-induced currents were action potential-independent and sensitive to strychnine, suggesting the involvement of glycine receptors. In addition, taurine activated not only α-homomeric, but also αβ-heteromeric glycine receptors in PHA neurons. Interestingly, a low concentration of taurine (0.5mM) activated glycine receptors, whereas a higher concentration (3mM) activated both glycine and gamma-aminobutyric acid A (GABAA) receptors in PHA neurons. These results suggest that PHA neurons are influenced by taurine and respond via glycine and GABAA receptors. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  13. Conjugation to the cell-penetrating peptide TAT potentiates the photodynamic effect of carboxytetramethylrhodamine.

    Directory of Open Access Journals (Sweden)

    Divyamani Srinivasan

    2011-03-01

    Full Text Available Cell-penetrating peptides (CPPs can transport macromolecular cargos into live cells. However, the cellular delivery efficiency of these reagents is often suboptimal because CPP-cargo conjugates typically remain trapped inside endosomes. Interestingly, irradiation of fluorescently labeled CPPs with light increases the release of the peptide and its cargos into the cytosol. However, the mechanism of this phenomenon is not clear. Here we investigate the molecular basis of the photo-induced endosomolytic activity of the prototypical CPPs TAT labeled to the fluorophore 5(6-carboxytetramethylrhodamine (TMR.We report that TMR-TAT acts as a photosensitizer that can destroy membranes. TMR-TAT escapes from endosomes after exposure to moderate light doses. However, this is also accompanied by loss of plasma membrane integrity, membrane blebbing, and cell-death. In addition, the peptide causes the destruction of cells when applied extracellularly and also triggers the photohemolysis of red blood cells. These photolytic and photocytotoxic effects were inhibited by hydrophobic singlet oxygen quenchers but not by hydrophilic quenchers.Together, these results suggest that TAT can convert an innocuous fluorophore such as TMR into a potent photolytic agent. This effect involves the targeting of the fluorophore to cellular membranes and the production of singlet oxygen within the hydrophobic environment of the membranes. Our findings may be relevant for the design of reagents with photo-induced endosomolytic activity. The photocytotoxicity exhibited by TMR-TAT also suggests that CPP-chromophore conjugates could aid the development of novel Photodynamic Therapy agents.

  14. rCBF activation studies and neuronal circuitry related to vision

    NARCIS (Netherlands)

    deJong, BM

    Three principles of neuronal interaction within cortically distributed networks are discussed PET-rCBF activation methods provide an opportunity to acquire insight in the distribution of functionally related areas of the human brain in vivo. The distinction of visual areas, activated by either

  15. Brain stimulation used as biofeedback in neuronal activation of the temporal lobe area in autistic children

    Directory of Open Access Journals (Sweden)

    Vernon Furtado da Silva

    2016-08-01

    Full Text Available ABSTRACT This study focused upon the functional capacity of mirror neurons in autistic children. 30 individuals, 10 carriers of the autistic syndrome (GCA, 10 with intellectual impairments (GDI, and 10 non-autistics (GCN had registered eletroencephalogram from the brain area theoretically related to mirror neurons. Data collection procedure occurred prior to brain stimulation and after the stimulation session. During the second session, participants had to alternately process figures evoking neutral, happy, and/or sorrowful feelings. Results proved that, for all groups, the stimulation process in fact produced additional activation in the neural area under study. The level of activation was related to the format of emotional stimuli and the likelihood of boosting such stimuli. Since the increase of activation occurred in a model similar to the one observed for the control group, we may suggest that the difficulty people with autism have at expressing emotions is not due to nonexistence of mirror neurons.

  16. Brain stimulation used as biofeedback in neuronal activation of the temporal lobe area in autistic children.

    Science.gov (United States)

    Silva, Vernon Furtado da; Calomeni, Mauricio Rocha; Nunes, Rodolfo Alkmim Moreira; Pimentel, Carlos Elias; Martins, Gabriela Paes; Oliveira, Patrícia da Cruz Araruna; Silva, Patrícia Bagno; Silva, Alair Pedro Ribeiro de Souza E

    2016-08-01

    This study focused upon the functional capacity of mirror neurons in autistic children. 30 individuals, 10 carriers of the autistic syndrome (GCA), 10 with intellectual impairments (GDI), and 10 non-autistics (GCN) had registered eletroencephalogram from the brain area theoretically related to mirror neurons. Data collection procedure occurred prior to brain stimulation and after the stimulation session. During the second session, participants had to alternately process figures evoking neutral, happy, and/or sorrowful feelings. Results proved that, for all groups, the stimulation process in fact produced additional activation in the neural area under study. The level of activation was related to the format of emotional stimuli and the likelihood of boosting such stimuli. Since the increase of activation occurred in a model similar to the one observed for the control group, we may suggest that the difficulty people with autism have at expressing emotions is not due to nonexistence of mirror neurons.

  17. Anti-inflammatory effects of Tat-Annexin protein on ovalbumin-induced airway inflammation in a mouse model of asthma

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sun Hwa; Kim, Dae Won; Kim, Hye Ri; Woo, Su Jung; Kim, So Mi; Jo, Hyo Sang [Department of Biomedical Science and Research Institute of Bioscience and Biotechnology, Hallym University, Chunchon 200-702 (Korea, Republic of); Jeon, Seong Gyu [Department of Life Science, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); Cho, Sung-Woo [Department of Biochemistry and Molecular Biology, University of Ulsan, College of Medicine, Seoul 138-736 (Korea, Republic of); Park, Jong Hoon [Department of Biological Science, Sookmyung Women' s University, Seoul 140-742 (Korea, Republic of); Won, Moo Ho [Department of Neurobiology, School of Medicine, Kangwon National University, Chuncheon 200-701 (Korea, Republic of); Park, Jinseu [Department of Biomedical Science and Research Institute of Bioscience and Biotechnology, Hallym University, Chunchon 200-702 (Korea, Republic of); Eum, Won Sik, E-mail: wseum@hallym.ac.kr [Department of Biomedical Science and Research Institute of Bioscience and Biotechnology, Hallym University, Chunchon 200-702 (Korea, Republic of); Choi, Soo Young, E-mail: sychoi@hallym.ac.kr [Department of Biomedical Science and Research Institute of Bioscience and Biotechnology, Hallym University, Chunchon 200-702 (Korea, Republic of)

    2012-01-20

    Highlights: Black-Right-Pointing-Pointer We construct a cell permeable Tat-ANX1 fusion protein. Black-Right-Pointing-Pointer We examined the protective effects of Tat-ANX1 protein on OVA-induced asthma in animal models. Black-Right-Pointing-Pointer Transduced Tat-ANX1 protein protects from the OVA-induced production of cytokines and eosinophils in BAL fluid. Black-Right-Pointing-Pointer Tat-ANX1 protein markedly reduced OVA-induced MAPK in lung tissues. Black-Right-Pointing-Pointer Tat-ANX1 protein could be useful as a therapeutic agent for lung disorders including asthma. -- Abstract: Chronic airway inflammation is a key feature of bronchial asthma. Annexin-1 (ANX1) is an anti-inflammatory protein that is an important modulator and plays a key role in inflammation. Although the precise action of ANX1 remains unclear, it has emerged as a potential drug target for inflammatory diseases such as asthma. To examine the protective effects of ANX1 protein on ovalbumin (OVA)-induced asthma in animal models, we used a cell-permeable Tat-ANX1 protein. Mice sensitized and challenged with OVA antigen had an increased amount of cytokines and eosinophils in their bronchoalveolar lavage (BAL) fluid. However, administration of Tat-ANX1 protein before OVA challenge significantly decreased the levels of cytokines (interleukin (IL)-4, IL-5, and IL-13) and BAL fluid in lung tissues. Furthermore, OVA significantly increased the activation of mitogen-activated protein kinase (MAPK) in lung tissues, whereas Tat-ANX1 protein markedly reduced phosphorylation of MAPKs such as extracellular signal-regulated protein kinase, p38, and stress-activated protein kinase/c-Jun N-terminal kinase. These results suggest that transduced Tat-ANX1 protein may be a potential protein therapeutic agent for the treatment of lung disorders including asthma.

  18. Cell-Type Specific Development of the Hyperpolarization-Activated Current, Ih, in Prefrontal Cortical Neurons

    Directory of Open Access Journals (Sweden)

    Sha-Sha Yang

    2018-05-01

    Full Text Available H-current, also known as hyperpolarization-activated current (Ih, is an inward current generated by the hyperpolarization-activated cyclic nucleotide-gated (HCN cation channels. Ih plays an essential role in regulating neuronal properties, synaptic integration and plasticity, and synchronous activity in the brain. As these biological factors change across development, the brain undergoes varying levels of vulnerability to disorders like schizophrenia that disrupt prefrontal cortex (PFC-dependent function. However, developmental changes in Ih in PFC neurons remains untested. Here, we examine Ih in pyramidal neurons vs. gamma-aminobutyric acid (GABAergic parvalbumin-expressing (PV+ interneurons in developing mouse PFC. Our findings show that the amplitudes of Ih in these cell types are identical during the juvenile period but differ at later time points. In pyramidal neurons, Ih amplitude significantly increases from juvenile to adolescence and follows a similar trend into adulthood. In contrast, the amplitude of Ih in PV+ interneurons decreases from juvenile to adolescence, and does not change from adolescence to adulthood. Moreover, the kinetics of HCN channels in pyramidal neurons is significantly slower than in PV+ interneurons, with a gradual decrease in pyramidal neurons and a gradual increase in PV+ cells across development. Our study reveals distinct developmental trajectories of Ih in pyramidal neurons and PV+ interneurons. The cell-type specific alteration of Ih during the critical period from juvenile to adolescence reflects the contribution of Ih to the maturation of the PFC and PFC-dependent function. These findings are essential for a better understanding of normal PFC function, and for elucidating Ih’s crucial role in the pathophysiology of neurodevelopmental disorders.

  19. Generation of NSE-MerCreMer transgenic mice with tamoxifen inducible Cre activity in neurons.

    Directory of Open Access Journals (Sweden)

    Mandy Ka Man Kam

    Full Text Available To establish a genetic tool for conditional deletion or expression of gene in neurons in a temporally controlled manner, we generated a transgenic mouse (NSE-MerCreMer, which expressed a tamoxifen inducible type of Cre recombinase specifically in neurons. The tamoxifen inducible Cre recombinase (MerCreMer is a fusion protein containing Cre recombinase with two modified estrogen receptor ligand binding domains at both ends, and is driven by the neural-specific rat neural specific enolase (NSE promoter. A total of two transgenic lines were established, and expression of MerCreMer in neurons of the central and enteric nervous systems was confirmed. Transcript of MerCreMer was detected in several non-neural tissues such as heart, liver, and kidney in these lines. In the background of the Cre reporter mouse strain Rosa26R, Cre recombinase activity was inducible in neurons of adult NSE-MerCreMer mice treated with tamoxifen by intragastric gavage, but not in those fed with corn oil only. We conclude that NSE-MerCreMer lines will be useful for studying gene functions in neurons for the conditions that Cre-mediated recombination resulting in embryonic lethality, which precludes investigation of gene functions in neurons through later stages of development and in adult.

  20. Converging Mechanisms of p53 Activation Drive Motor Neuron Degeneration in Spinal Muscular Atrophy

    Directory of Open Access Journals (Sweden)

    Christian M. Simon

    2017-12-01

    Full Text Available The hallmark of spinal muscular atrophy (SMA, an inherited disease caused by ubiquitous deficiency in the SMN protein, is the selective degeneration of subsets of spinal motor neurons. Here, we show that cell-autonomous activation of p53 occurs in vulnerable but not resistant motor neurons of SMA mice at pre-symptomatic stages. Moreover, pharmacological or genetic inhibition of p53 prevents motor neuron death, demonstrating that induction of p53 signaling drives neurodegeneration. At late disease stages, however, nuclear accumulation of p53 extends to resistant motor neurons and spinal interneurons but is not associated with cell death. Importantly, we identify phosphorylation of serine 18 as a specific post-translational modification of p53 that exclusively marks vulnerable SMA motor neurons and provide evidence that amino-terminal phosphorylation of p53 is required for the neurodegenerative process. Our findings indicate that distinct events induced by SMN deficiency converge on p53 to trigger selective death of vulnerable SMA motor neurons.

  1. The endogenous alkaloid harmane: acidifying and activity-reducing effects on hippocampal neurons in vitro.

    Science.gov (United States)

    Bonnet, Udo; Scherbaum, Norbert; Wiemann, Martin

    2008-02-15

    The endogenous alkaloid harmane is enriched in plasma of patients with neurodegenerative or addictive disorders. As harmane affects neuronal activity and viability and because both parameters are strongly influenced by intracellular pH (pH(i)), we tested whether effects of harmane are correlated with altered pH(i) regulation. Pyramidal neurons in the CA3 field of hippocampal slices were investigated under bicarbonate-buffered conditions. Harmane (50 and 100 microM) reversibly decreased spontaneous firing of action potentials and caffeine-induced bursting of CA3 neurons. In parallel experiments, 50 and 100 microM harmane evoked a neuronal acidification of 0.12+/-0.08 and 0.18+/-0.07 pH units, respectively. Recovery from intracellular acidification subsequent to an ammonium prepulse was also impaired, suggesting an inhibition of transmembrane acid extrusion by harmane. Harmane may modulate neuronal functions via altered pH(i)-regulation. Implications of these findings for neuronal survival are discussed.

  2. A computational paradigm for dynamic logic-gates in neuronal activity

    Directory of Open Access Journals (Sweden)

    Amir eGoldental

    2014-04-01

    Full Text Available In 1943 McCulloch and Pitts suggested that the brain is composed of reliable logic-gates similar to the logic at the core of today's computers. This framework had a limited impact on neuroscience, since neurons exhibit far richer dynamics. Here we propose a new experimentally corroborated paradigm in which the truth tables of the brain's logic-gates are time dependent, i.e. dynamic logic-gates (DLGs. The truth tables of the DLGs depend on the history of their activity and the stimulation frequencies of their input neurons. Our experimental results are based on a procedure where conditioned stimulations were enforced on circuits of neurons embedded within a large-scale network of cortical cells in-vitro. We demonstrate that the underlying biological mechanism is the unavoidable increase of neuronal response latencies to ongoing stimulations, which imposes a non-uniform gradual stretching of network delays. The limited experimental results are confirmed and extended by simulations and theoretical arguments based on identical neurons with a fixed increase of the neuronal response latency per evoked spike. We anticipate our results to lead to better understanding of the suitability of this computational paradigm to account for the brain's functionalities and will require the development of new systematic mathematical methods beyond the methods developed for traditional Boolean algebra.

  3. Activation of murine pre-proglucagon-producing neurons reduces food intake and body weight.

    Science.gov (United States)

    Gaykema, Ronald P; Newmyer, Brandon A; Ottolini, Matteo; Raje, Vidisha; Warthen, Daniel M; Lambeth, Philip S; Niccum, Maria; Yao, Ting; Huang, Yiru; Schulman, Ira G; Harris, Thurl E; Patel, Manoj K; Williams, Kevin W; Scott, Michael M

    2017-03-01

    Peptides derived from pre-proglucagon (GCG peptides) act in both the periphery and the CNS to change food intake, glucose homeostasis, and metabolic rate while playing a role in anxiety behaviors and physiological responses to stress. Although the actions of GCG peptides produced in the gut and pancreas are well described, the role of glutamatergic GGC peptide-secreting hindbrain neurons in regulating metabolic homeostasis has not been investigated. Here, we have shown that chemogenetic stimulation of GCG-producing neurons reduces metabolic rate and food intake in fed and fasted states and suppresses glucose production without an effect on glucose uptake. Stimulation of GCG neurons had no effect on corticosterone secretion, body weight, or conditioned taste aversion. In the diet-induced obese state, the effects of GCG neuronal stimulation on gluconeogenesis were lost, while the food intake-lowering effects remained, resulting in reductions in body weight and adiposity. Our work suggests that GCG peptide-expressing neurons can alter feeding, metabolic rate, and glucose production independent of their effects on hypothalamic pituitary-adrenal (HPA) axis activation, aversive conditioning, or insulin secretion. We conclude that GCG neurons likely stimulate separate populations of downstream cells to produce a change in food intake and glucose homeostasis and that these effects depend on the metabolic state of the animal.

  4. Activation of murine pre-proglucagon–producing neurons reduces food intake and body weight

    Science.gov (United States)

    Gaykema, Ronald P.; Newmyer, Brandon A.; Ottolini, Matteo; Warthen, Daniel M.; Lambeth, Philip S.; Niccum, Maria; Yao, Ting; Huang, Yiru; Schulman, Ira G.; Harris, Thurl E.; Patel, Manoj K.; Williams, Kevin W.

    2017-01-01

    Peptides derived from pre-proglucagon (GCG peptides) act in both the periphery and the CNS to change food intake, glucose homeostasis, and metabolic rate while playing a role in anxiety behaviors and physiological responses to stress. Although the actions of GCG peptides produced in the gut and pancreas are well described, the role of glutamatergic GGC peptide–secreting hindbrain neurons in regulating metabolic homeostasis has not been investigated. Here, we have shown that chemogenetic stimulation of GCG-producing neurons reduces metabolic rate and food intake in fed and fasted states and suppresses glucose production without an effect on glucose uptake. Stimulation of GCG neurons had no effect on corticosterone secretion, body weight, or conditioned taste aversion. In the diet-induced obese state, the effects of GCG neuronal stimulation on gluconeogenesis were lost, while the food intake–lowering effects remained, resulting in reductions in body weight and adiposity. Our work suggests that GCG peptide–expressing neurons can alter feeding, metabolic rate, and glucose production independent of their effects on hypothalamic pituitary-adrenal (HPA) axis activation, aversive conditioning, or insulin secretion. We conclude that GCG neurons likely stimulate separate populations of downstream cells to produce a change in food intake and glucose homeostasis and that these effects depend on the metabolic state of the animal. PMID:28218622

  5. Activation of temperature-sensitive TRPV1-like receptors in ARC POMC neurons reduces food intake.

    Directory of Open Access Journals (Sweden)

    Jae Hoon Jeong

    2018-04-01

    Full Text Available Proopiomelanocortin (POMC neurons in the arcuate nucleus of the hypothalamus (ARC respond to numerous hormonal and neural signals, resulting in changes in food intake. Here, we demonstrate that ARC POMC neurons express capsaicin-sensitive transient receptor potential vanilloid 1 receptor (TRPV1-like receptors. To show expression of TRPV1-like receptors in ARC POMC neurons, we use single-cell reverse transcription-polymerase chain reaction (RT-PCR, immunohistochemistry, electrophysiology, TRPV1 knock-out (KO, and TRPV1-Cre knock-in mice. A small elevation of temperature in the physiological range is enough to depolarize ARC POMC neurons. This depolarization is blocked by the TRPV1 receptor antagonist and by Trpv1 gene knockdown. Capsaicin-induced activation reduces food intake that is abolished by a melanocortin receptor antagonist. To selectively stimulate TRPV1-like receptor-expressing ARC POMC neurons in the ARC, we generate an adeno-associated virus serotype 5 (AAV5 carrying a Cre-dependent channelrhodopsin-2 (ChR2-enhanced yellow fluorescent protein (eYFP expression cassette under the control of the two neuronal POMC enhancers (nPEs. Optogenetic stimulation of TRPV1-like receptor-expressing POMC neurons decreases food intake. Hypothalamic temperature is rapidly elevated and reaches to approximately 39 °C during treadmill running. This elevation is associated with a reduction in food intake. Knockdown of the Trpv1 gene exclusively in ARC POMC neurons blocks the feeding inhibition produced by increased hypothalamic temperature. Taken together, our findings identify a melanocortinergic circuit that links acute elevations in hypothalamic temperature with acute reductions in food intake.

  6. The contribution of ketone bodies to basal and activity-dependent neuronal oxidation in vivo.

    Science.gov (United States)

    Chowdhury, Golam M I; Jiang, Lihong; Rothman, Douglas L; Behar, Kevin L

    2014-07-01

    The capacity of ketone bodies to replace glucose in support of neuronal function is unresolved. Here, we determined the contributions of glucose and ketone bodies to neocortical oxidative metabolism over a large range of brain activity in rats fasted 36 hours and infused intravenously with [2,4-(13)C₂]-D-β-hydroxybutyrate (BHB). Three animal groups and conditions were studied: awake ex vivo, pentobarbital-induced isoelectricity ex vivo, and halothane-anesthetized in vivo, the latter data reanalyzed from a recent study. Rates of neuronal acetyl-CoA oxidation from ketone bodies (V(acCoA-kbN)) and pyruvate (V(pdhN)), and the glutamate-glutamine cycle (V(cyc)) were determined by metabolic modeling of (13)C label trapped in major brain amino acid pools. V(acCoA-kbN) increased gradually with increasing activity, as compared with the steeper change in tricarboxylic acid (TCA) cycle rate (V(tcaN)), supporting a decreasing percentage of neuronal ketone oxidation: ∼100% (isoelectricity), 56% (halothane anesthesia), 36% (awake) with the BHB plasma levels achieved in our experiments (6 to 13 mM). In awake animals ketone oxidation reached saturation for blood levels >17 mM, accounting for 62% of neuronal substrate oxidation, the remainder (38%) provided by glucose. We conclude that ketone bodies present at sufficient concentration to saturate metabolism provides full support of basal (housekeeping) energy needs and up to approximately half of the activity-dependent oxidative needs of neurons.

  7. Interplay of activation kinetics and the derivative conductance determines resonance properties of neurons

    Science.gov (United States)

    Pena, Rodrigo F. O.; Ceballos, Cesar C.; Lima, Vinicius; Roque, Antonio C.

    2018-04-01

    In a neuron with hyperpolarization activated current (Ih), the correct input frequency leads to an enhancement of the output response. This behavior is known as resonance and is well described by the neuronal impedance. In a simple neuron model we derive equations for the neuron's resonance and we link its frequency and existence with the biophysical properties of Ih. For a small voltage change, the component of the ratio of current change to voltage change (d I /d V ) due to the voltage-dependent conductance change (d g /d V ) is known as derivative conductance (GhDer). We show that both GhDer and the current activation kinetics (characterized by the activation time constant τh) are mainly responsible for controlling the frequency and existence of resonance. The increment of both factors (GhDer and τh) greatly contributes to the appearance of resonance. We also demonstrate that resonance is voltage dependent due to the voltage dependence of GhDer. Our results have important implications and can be used to predict and explain resonance properties of neurons with the Ih current.

  8. Male mice ultrasonic vocalizations enhance female sexual approach and hypothalamic kisspeptin neuron activity.

    Science.gov (United States)

    Asaba, Akari; Osakada, Takuya; Touhara, Kazushige; Kato, Masahiro; Mogi, Kazutaka; Kikusui, Takefumi

    2017-08-01

    Vocal communication in animals is important for ensuring reproductive success. Male mice emit song-like "ultrasonic vocalizations (USVs)" when they encounter female mice, and females show approach to the USVs. However, it is unclear whether USVs of male mice trigger female behavioral and endocrine responses in reproduction. In this study, we first investigated the relationship between the number of deliveries in breeding pairs for 4months and USVs syllables emitted from those paired males during 3min of sexual encounter with unfamiliar female mice. There was a positive correlation between these two indices, which suggests that breeding pairs in which males could emit USVs more frequently had more offspring. Further, we examined the effect of USVs of male mice on female sexual behavior. Female mice showed more approach behavior towards vocalizing males than devocalized males. Finally, to determine whether USVs of male mice could activate the neural system governing reproductive function in female mice, the activation of kisspeptin neurons, key neurons to drive gonadotropin-releasing hormone neurons in the hypothalamus, was examined using dual-label immunocytochemistry with cAMP response element-binding protein phosphorylation (pCREB). In the arcuate nucleus (Arc), the number of kisspeptin neurons expressing pCREB significantly increased after exposure to USVs of male as compared with noise exposure group. In conclusion, our results suggest that USVs of male mice promote fertility in female mice by activating both their approaching behavior and central kisspeptin neurons. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Evidence for conformational flexibility in the Tat-TAR recognition motif of cyclin T1

    International Nuclear Information System (INIS)

    Das, Chandreyee; Edgcomb, Stephen P.; Peteranderl, Ralph; Chen, Lily; Frankel, Alan D.

    2004-01-01

    Cyclin T1 (CycT1) is a cellular transcription elongation factor that also participates in Tat-mediated activation of several lentiviral promoters. In human immunodeficiency virus (HIV), CycT1 is required for Tat to bind tightly to TAR and interacts in the ternary complex via its Tat-TAR recognition motif (TRM). In the related bovine immunodeficiency virus (BIV), Tat recognizes its cognate TAR element with high affinity and specificity in the absence of CycT1. At both promoters, CycT1 recruits the Cdk9 kinase, which phosphorylates RNA polymerase II to generate processive transcription complexes. To examine the physical properties of CycT1, we purified a functional domain corresponding to residues 1-272 and found that it possesses a stably folded core, as judged by partial proteolysis and circular dichroism experiments. Interestingly, the C-terminal 20 residues corresponding to the TRM appear conformationally flexible or disordered. The TRM of the bovine CycT1 (bCycT1) is similarly sensitive to proteolysis yet differs in sequence from the human protein. In particular, bCycT1 lacks a cysteine at residue 261 known to be critical for HIV but not BIV ternary complex formation, and mutagenesis data are consistent with a proposed role for this cysteine in metal binding. The apparent flexibility of the TRM suggests that conformational rearrangements may accompany formation of CycT1-Tat-TAR ternary complexes and may contribute to different TAR recognition strategies in different lentiviruses

  10. Building Capacity in Using Earth Observations Under the GOFC-GOLD and TAT Programs

    Science.gov (United States)

    Gutman, G.

    2015-12-01

    The Global Observation of Forest and Land Cover Dynamics (GOFC-GOLD) is a coordinated international effort to provide ongoing space-based and in-situ observations of forests and other vegetation cover. The main goal of GOFC/GOLD is to support a forum for international information exchange, observation and data coordination, and a framework for establishing the necessary long-term monitoring systems. GOFC-GOLD has two Implementation Teams: Land Cover Characteristics and Change, and Fire Monitoring and Mapping. Additionally, it includes two working groups: the Working Group on Biomass Monitoring and the Working group on Reducing Emissions from Deforestation and Forest Degradation (REDD), the latter being aligned with the United Nations Framework Convention on Climate Change. Regional networks are an integral part of the GOFC-GOLD program, with some networks fully developed and some still emerging. GOFC-GOLD provides training workshops to build capacity in the regions. Capacity building in using Earth Observation techniques and applications is also promoted by cooperation of NASA and ESA under the Trans-Atlantic Training (TAT) program. The main objective of TAT is training of early career scientists and students in East European and Baltic countries emphasizing outstanding technical issues in remote sensing of land-cover/land-use change and ecosystems processes. TAT promotes data sharing and advanced research methods and technologies through series of training sessions. Three TAT sessions have been held until now, each session consisting of 5-10 tutors and about 30 early career scientists and students from Eastern Europe. The sessions include lectures on remote sensing covering the full solar spectrum and hands-on practice. The experience obtained in capacity building activities under GOFC-GOLD and TAT will be shared with the audience.

  11. Optogenetic activation of dorsal raphe serotonin neurons enhances patience for future rewards.

    Science.gov (United States)

    Miyazaki, Kayoko W; Miyazaki, Katsuhiko; Tanaka, Kenji F; Yamanaka, Akihiro; Takahashi, Aki; Tabuchi, Sawako; Doya, Kenji

    2014-09-08

    Serotonin is a neuromodulator that is involved extensively in behavioral, affective, and cognitive functions in the brain. Previous recording studies of the midbrain dorsal raphe nucleus (DRN) revealed that the activation of putative serotonin neurons correlates with the levels of behavioral arousal [1], rhythmic motor outputs [2], salient sensory stimuli [3-6], reward, and conditioned cues [5-8]. The classic theory on serotonin states that it opposes dopamine and inhibits behaviors when aversive events are predicted [9-14]. However, the therapeutic effects of serotonin signal-enhancing medications have been difficult to reconcile with this theory [15, 16]. In contrast, a more recent theory states that serotonin facilitates long-term optimal behaviors and suppresses impulsive behaviors [17-21]. To test these theories, we developed optogenetic mice that selectively express channelrhodopsin in serotonin neurons and tested how the activation of serotonergic neurons in the DRN affects animal behavior during a delayed reward task. The activation of serotonin neurons reduced the premature cessation of waiting for conditioned cues and food rewards. In reward omission trials, serotonin neuron stimulation prolonged the time animals spent waiting. This effect was observed specifically when the animal was engaged in deciding whether to keep waiting and was not due to motor inhibition. Control experiments showed that the prolonged waiting times observed with optogenetic stimulation were not due to behavioral inhibition or the reinforcing effects of serotonergic activation. These results show, for the first time, that the timed activation of serotonin neurons during waiting promotes animals' patience to wait for a delayed reward. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Egalitarian reward contingency in competitive games and primate prefrontal neuronal activity.

    Science.gov (United States)

    Hosokawa, Takayuki; Watanabe, Masataka

    2015-01-01

    How people work to obtain a reward depends on the context of the reward delivery, such as the presence/absence of competition and the contingency of reward delivery. Since resources are limited, winning a competition is critically important for organisms' obtaining a reward. People usually expect ordinary performance-reward contingency, with better performers obtaining better rewards. Unordinary reward contingency, such as egalitarianism (equal rewards/no-rewards to both good and poor performers), dampens people's motivation. We previously reported that monkeys were more motivated, and neurons in the lateral prefrontal cortex (LPFC) showed higher outcome-related activity in a competitive than in a noncompetitive game (Hosokawa and Watanabe, 2012). However, monkey's behavior and LPFC neuronal activity have not been examined in a competitive situation with an unordinary performance-reward contingency. Also, the fixed performance-reward contingency in the previous study did not allow us to examine effects of win/loss separately from those of reward/no-reward on prefrontal neuronal activity. Here, we employed the egalitarian competitive situation in which both the winner and loser, or neither of them, got a reward as well as the normal competitive situation in which only the winner got a reward. Monkey's behavioral performance greatly deteriorated in trials with the egalitarian outcome conditions. LPFC neurons showed activities that reflected the normal or egalitarian outcome condition while very few neurons coded win/loss independent of reward/no-reward. Importantly, we found neurons that showed reward-related activity in the normal, but not in the egalitarian outcome conditions, even though the same reward was given to the animal. These results indicate that LPFC may play an important role in monitoring the current reward contingency and integrating it with the performance outcome (win-loss) for better performing the competitive game, and thus for better survival.

  13. Entrained rhythmic activities of neuronal ensembles as perceptual memory of time interval.

    Science.gov (United States)

    Sumbre, Germán; Muto, Akira; Baier, Herwig; Poo, Mu-ming

    2008-11-06

    The ability to process temporal information is fundamental to sensory perception, cognitive processing and motor behaviour of all living organisms, from amoebae to humans. Neural circuit mechanisms based on neuronal and synaptic properties have been shown to process temporal information over the range of tens of microseconds to hundreds of milliseconds. How neural circuits process temporal information in the range of seconds to minutes is much less understood. Studies of working memory in monkeys and rats have shown that neurons in the prefrontal cortex, the parietal cortex and the thalamus exhibit ramping activities that linearly correlate with the lapse of time until the end of a specific time interval of several seconds that the animal is trained to memorize. Many organisms can also memorize the time interval of rhythmic sensory stimuli in the timescale of seconds and can coordinate motor behaviour accordingly, for example, by keeping the rhythm after exposure to the beat of music. Here we report a form of rhythmic activity among specific neuronal ensembles in the zebrafish optic tectum, which retains the memory of the time interval (in the order of seconds) of repetitive sensory stimuli for a duration of up to approximately 20 s. After repetitive visual conditioning stimulation (CS) of zebrafish larvae, we observed rhythmic post-CS activities among specific tectal neuronal ensembles, with a regular interval that closely matched the CS. Visuomotor behaviour of the zebrafish larvae also showed regular post-CS repetitions at the entrained time interval that correlated with rhythmic neuronal ensemble activities in the tectum. Thus, rhythmic activities among specific neuronal ensembles may act as an adjustable 'metronome' for time intervals in the order of seconds, and serve as a mechanism for the short-term perceptual memory of rhythmic sensory experience.

  14. Inward rectifier potassium current IKir promotes intrinsic pacemaker activity of thalamocortical neurons.

    Science.gov (United States)

    Amarillo, Yimy; Tissone, Angela I; Mato, Germán; Nadal, Marcela S

    2018-06-01

    Slow repetitive burst firing by hyperpolarized thalamocortical (TC) neurons correlates with global slow rhythms (rectifier potassium current I Kir induces repetitive burst firing at slow and delta frequency bands. We demonstrate this in mouse TC neurons in brain slices by manipulating the Kir maximum conductance with dynamic clamp. We also performed a thorough theoretical analysis that explains how the unique properties of I Kir enable this current to induce slow periodic bursting in TC neurons. We describe a new ionic mechanism based on the voltage- and time-dependent interaction of I Kir and hyperpolarization-activated cationic current I h that endows TC neurons with the ability to oscillate spontaneously at very low frequencies, even below 0.5 Hz. Bifurcation analysis of conductance-based models of increasing complexity demonstrates that I Kir induces bistability of the membrane potential at the same time that it induces sustained oscillations in combination with I h and increases the robustness of low threshold-activated calcium current I T -mediated oscillations. NEW & NOTEWORTHY The strong inwardly rectifying potassium current I Kir of thalamocortical neurons displays a region of negative slope conductance in the current-voltage relationship that generates potassium currents activated by hyperpolarization. Bifurcation analysis shows that I Kir induces bistability of the membrane potential; generates sustained subthreshold oscillations by interacting with the hyperpolarization-activated cationic current I h ; and increases the robustness of oscillations mediated by the low threshold-activated calcium current I T . Upregulation of I Kir in thalamocortical neurons induces repetitive burst firing at slow and delta frequency bands (<4 Hz).

  15. Operant conditioning of synaptic and spiking activity patterns in single hippocampal neurons.

    Science.gov (United States)

    Ishikawa, Daisuke; Matsumoto, Nobuyoshi; Sakaguchi, Tetsuya; Matsuki, Norio; Ikegaya, Yuji

    2014-04-02

    Learning is a process of plastic adaptation through which a neural circuit generates a more preferable outcome; however, at a microscopic level, little is known about how synaptic activity is patterned into a desired configuration. Here, we report that animals can generate a specific form of synaptic activity in a given neuron in the hippocampus. In awake, head-restricted mice, we applied electrical stimulation to the lateral hypothalamus, a reward-associated brain region, when whole-cell patch-clamped CA1 neurons exhibited spontaneous synaptic activity that met preset criteria. Within 15 min, the mice learned to generate frequently the excitatory synaptic input pattern that satisfied the criteria. This reinforcement learning of synaptic activity was not observed for inhibitory input patterns. When a burst unit activity pattern was conditioned in paired and nonpaired paradigms, the frequency of burst-spiking events increased and decreased, respectively. The burst reinforcement occurred in the conditioned neuron but not in other adjacent neurons; however, ripple field oscillations were concomitantly reinforced. Neural conditioning depended on activation of NMDA receptors and dopamine D1 receptors. Acutely stressed mice and depression model mice that were subjected to forced swimming failed to exhibit the neural conditioning. This learning deficit was rescued by repetitive treatment with fluoxetine, an antidepressant. Therefore, internally motivated animals are capable of routing an ongoing action potential series into a specific neural pathway of the hippocampal network.

  16. Manganese nanoparticle activates mitochondrial dependent apoptotic signaling and autophagy in dopaminergic neuronal cells

    International Nuclear Information System (INIS)

    Afeseh Ngwa, Hilary; Kanthasamy, Arthi; Gu, Yan; Fang, Ning; Anantharam, Vellareddy; Kanthasamy, Anumantha G.

    2011-01-01

    The production of man-made nanoparticles for various modern applications has increased exponentially in recent years, but the potential health effects of most nanoparticles are not well characterized. Unfortunately, in vitro nanoparticle toxicity studies are extremely limited by yet unresolved problems relating to dosimetry. In the present study, we systematically characterized manganese (Mn) nanoparticle sizes and examined the nanoparticle-induced oxidative signaling in dopaminergic neuronal cells. Differential interference contrast (DIC) microscopy and transmission electron microscopy (TEM) studies revealed that Mn nanoparticles range in size from single nanoparticles (∼ 25 nM) to larger agglomerates when in treatment media. Manganese nanoparticles were effectively internalized in N27 dopaminergic neuronal cells, and they induced a time-dependent upregulation of the transporter protein transferrin. Exposure to 25–400 μg/mL Mn nanoparticles induced cell death in a time- and dose-dependent manner. Mn nanoparticles also significantly increased ROS, accompanied by a caspase-mediated proteolytic cleavage of proapoptotic protein kinase Cδ (PKCδ), as well as activation loop phosphorylation. Blocking Mn nanoparticle-induced ROS failed to protect against the neurotoxic effects, suggesting the involvement of other pathways. Further mechanistic studies revealed changes in Beclin 1 and LC3, indicating that Mn nanoparticles induce autophagy. Primary mesencephalic neuron exposure to Mn nanoparticles induced loss of TH positive dopaminergic neurons and neuronal processes. Collectively, our results suggest that Mn nanoparticles effectively enter dopaminergic neuronal cells and exert neurotoxic effects by activating an apoptotic signaling pathway and autophagy, emphasizing the need for assessing possible health risks associated with an increased use of Mn nanoparticles in modern applications. -- Highlights: ► Mn nanoparticles activate mitochondrial cell death signaling

  17. Orexin-A increases the firing activity of hippocampal CA1 neurons through orexin-1 receptors.

    Science.gov (United States)

    Chen, Xin-Yi; Chen, Lei; Du, Yi-Feng

    2017-07-01

    Orexins including two peptides, orexin-A and orexin-B, are produced in the posterior lateral hypothalamus. Much evidence has indicated that central orexinergic systems play numerous functions including energy metabolism, feeding behavior, sleep/wakefulness, and neuroendocrine and sympathetic activation. Morphological studies have shown that the hippocampal CA1 regions receive orexinergic innervation originating from the hypothalamus. Positive orexin-1 (OX 1 ) receptors are detected in the CA1 regions. Previous behavioral studies have shown that microinjection of OX 1 receptor antagonist into the hippocampus impairs acquisition and consolidation of spatial memory. However, up to now, little has been known about the direct electrophysiological effects of orexin-A on hippocampal CA1 neurons. Employing multibarrel single-unit extracellular recordings, the present study showed that micropressure administration of orexin-A significantly increased the spontaneous firing rate from 2.96 ± 0.85 to 8.45 ± 1.86 Hz (P neurons in male rats. Furthermore, application of the specific OX 1 receptor antagonist SB-334867 alone significantly decreased the firing rate from 4.02 ± 1.08 to 2.11 ± 0.58 Hz in 7 out of the 17 neurons (P neurons. Coapplication of SB-334867 completely blocked orexin-A-induced excitation of hippocampal CA1 neurons. The PLC pathway may be involved in activation of OX 1 receptor-induced excitation of CA1 neurons. Taken together, the present study's results suggest that orexin-A produces excitatory effects on hippocampal neurons via OX 1 receptors. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  18. Neuronal thresholds and choice-related activity of otolith afferent fibers during heading perception.

    Science.gov (United States)

    Yu, Xiong-jie; Dickman, J David; DeAngelis, Gregory C; Angelaki, Dora E

    2015-05-19

    How activity of sensory neurons leads to perceptual decisions remains a challenge to understand. Correlations between choices and single neuron firing rates have been found early in vestibular processing, in the brainstem and cerebellum. To investigate the origins of choice-related activity, we have recorded from otolith afferent fibers while animals performed a fine heading discrimination task. We find that afferent fibers have similar discrimination thresholds as central cells, and the most sensitive fibers have thresholds that are only twofold or threefold greater than perceptual thresholds. Unlike brainstem and cerebellar nuclei neurons, spike counts from afferent fibers do not exhibit trial-by-trial correlations with perceptual decisions. This finding may reflect the fact that otolith afferent responses are poorly suited for driving heading perception because they fail to discriminate self-motion from changes in orientation relative to gravity. Alternatively, if choice probabilities reflect top-down inference signals, they are not relayed to the vestibular periphery.

  19. Noise focusing and the emergence of coherent activity in neuronal cultures

    Science.gov (United States)

    Orlandi, Javier G.; Soriano, Jordi; Alvarez-Lacalle, Enrique; Teller, Sara; Casademunt, Jaume

    2013-09-01

    At early stages of development, neuronal cultures in vitro spontaneously reach a coherent state of collective firing in a pattern of nearly periodic global bursts. Although understanding the spontaneous activity of neuronal networks is of chief importance in neuroscience, the origin and nature of that pulsation has remained elusive. By combining high-resolution calcium imaging with modelling in silico, we show that this behaviour is controlled by the propagation of waves that nucleate randomly in a set of points that is specific to each culture and is selected by a non-trivial interplay between dynamics and topology. The phenomenon is explained by the noise focusing effect--a strong spatio-temporal localization of the noise dynamics that originates in the complex structure of avalanches of spontaneous activity. Results are relevant to neuronal tissues and to complex networks with integrate-and-fire dynamics and metric correlations, for instance, in rumour spreading on social networks.

  20. Neuronal DNA Methyltransferases: Epigenetic Mediators between Synaptic Activity and Gene Expression?

    Science.gov (United States)

    Bayraktar, Gonca; Kreutz, Michael R

    2018-04-01

    DNMT3A and 3B are the main de novo DNA methyltransferases (DNMTs) in the brain that introduce new methylation marks to non-methylated DNA in postmitotic neurons. DNA methylation is a key epigenetic mark that is known to regulate important cellular processes in neuronal development and brain plasticity. Accumulating evidence disclosed rapid and dynamic changes in DNA methylation of plasticity-relevant genes that are important for learning and memory formation. To understand how DNMTs contribute to brain function and how they are regulated by neuronal activity is a prerequisite for a deeper appreciation of activity-dependent gene expression in health and disease. This review discusses the functional role of de novo methyltransferases and in particular DNMT3A1 in the adult brain with special emphasis on synaptic plasticity, memory formation, and brain disorders.

  1. The age of enlightenment: evolving opportunities in brain research through optical manipulation of neuronal activity

    Directory of Open Access Journals (Sweden)

    Jason eJerome

    2011-12-01

    Full Text Available Optical manipulation of neuronal activity has rapidly developed into the most powerful and widely used approach to study mechanisms related to neuronal connectivity over a range of scales. Since the early use of single site uncaging to map network connectivity, rapid technological development of light modulation techniques has added important new options, such as fast scanning photostimulation, massively parallel control of light stimuli, holographic uncaging and 2-photon stimulation techniques. Exciting new developments in optogenetics complement neurotransmitter uncaging techniques by providing cell-type specificity and in vivo usability, providing optical access to the neural substrates of behavior. Here we review the rapid evolution of methods for the optical manipulation of neuronal activity, emphasizing crucial recent developments.

  2. The age of enlightenment: evolving opportunities in brain research through optical manipulation of neuronal activity.

    Science.gov (United States)

    Jerome, Jason; Heck, Detlef H

    2011-01-01

    Optical manipulation of neuronal activity has rapidly developed into the most powerful and widely used approach to study mechanisms related to neuronal connectivity over a range of scales. Since the early use of single site uncaging to map network connectivity, rapid technological development of light modulation techniques has added important new options, such as fast scanning photostimulation, massively parallel control of light stimuli, holographic uncaging, and two-photon stimulation techniques. Exciting new developments in optogenetics complement neurotransmitter uncaging techniques by providing cell-type specificity and in vivo usability, providing optical access to the neural substrates of behavior. Here we review the rapid evolution of methods for the optical manipulation of neuronal activity, emphasizing crucial recent developments.

  3. Effect of the peptide Tat(49-57) on the bio-distribution and similar radiopharmaceuticals dosimetry of the bombesin; Efecto del peptido TAT(49-57) sobre la biodistribucion y dosimetria de radiofarmacos analogos de la bombesina

    Energy Technology Data Exchange (ETDEWEB)

    Santos C, C. L.

    2011-07-01

    The gastrin-releasing peptide receptor (GRP-r) is over-expressed in prostate and breast cancer. {sup 99m}Tc-Bombesin ({sup 99m}Tc-Bn) has been reported as a radiopharmaceutical with specific cell GRP-r binding. The HIV Tat(49-57)-derived peptide has been used to deliver a large variety of molecules to cell nuclei. New hybrid radiopharmaceuticals of type {sup 99m}Tc-N{sub 2}S{sub 2}-Tat(49-57)-Lys{sup 3}-Bn ({sup 99m}Tc-Tat-Bn) and {sup 188}Re-N{sub 2}S{sub 2}-Tat(49-57)-Lys{sup 3}-Bn ({sup 188}Re-Tat-Bn), would increase cell uptake and internalized in cancer cell nuclei could act as an effective system of targeted radiotherapy using Auger and internal conversion (I C) electron emissions near DNA. The aim of this research was to prepare and assess in vitro and in vivo uptake kinetics in cancer cells of {sup 99m}Tc/{sup 188}Re-Tat-Bn and the in vitro nucleus and cytoplasm internalization kinetics in GRP receptor-positive cancer cells as well as to evaluate the subcellular-level radiation absorbed dose associated with the observed effect on cancer cell DNA proliferation. Structures of N{sub 2}S{sub 2}-Tat-Bn and Tc/Re(O)N{sub 2}S{sub 2}-Tat-Bn were calculated by an Mm procedure. {sup 99m}Tc-Tat-Bn and {sup 188}Re-Tat-Bn were synthesized and stability studies carried out by HPLC and I TLC-Sg analyses in serum and cysteine solutions. In vitro internalization was tested using human prostate cancer Pc 3 cells and breast carcinoma cell lines MDA-Mb 231 and MCF 7. Nuclei from cells were isolated using a nuclear extraction kit. Total disintegrations in each subcellular compartment were calculated by integration of experimental time activity kinetic curves. Nucleus internalization was corroborated by con focal microscopy images using immunofluorescent labelled Tat-Bn. Biodistribution was determined in Pc 3 tumor-bearing nude mice. The Penelope code was used to simulate and calculate the absorbed dose by contribution of {beta}, Auger and I C electrons in the cytoplasm and

  4. Parallel optical control of spatiotemporal neuronal spike activity using high-frequency digital light processingtechnology

    Directory of Open Access Journals (Sweden)

    Jason eJerome

    2011-08-01

    Full Text Available Neurons in the mammalian neocortex receive inputs from and communicate back to thousands of other neurons, creating complex spatiotemporal activity patterns. The experimental investigation of these parallel dynamic interactions has been limited due to the technical challenges of monitoring or manipulating neuronal activity at that level of complexity. Here we describe a new massively parallel photostimulation system that can be used to control action potential firing in in vitro brain slices with high spatial and temporal resolution while performing extracellular or intracellular electrophysiological measurements. The system uses Digital-Light-Processing (DLP technology to generate 2-dimensional (2D stimulus patterns with >780,000 independently controlled photostimulation sites that operate at high spatial (5.4 µm and temporal (>13kHz resolution. Light is projected through the quartz-glass bottom of the perfusion chamber providing access to a large area (2.76 x 2.07 mm2 of the slice preparation. This system has the unique capability to induce temporally precise action potential firing in large groups of neurons distributed over a wide area covering several cortical columns. Parallel photostimulation opens up new opportunities for the in vitro experimental investigation of spatiotemporal neuronal interactions at a broad range of anatomical scales.

  5. Central GLP-2 enhances hepatic insulin sensitivity via activating PI3K signaling in POMC neurons

    Science.gov (United States)

    Shi, Xuemei; Zhou, Fuguo; Li, Xiaojie; Chang, Benny; Li, Depei; Wang, Yi; Tong, Qingchun; Xu, Yong; Fukuda, Makoto; Zhao, Jean J.; Li, Defa; Burrin, Douglas G.; Chan, Lawrence; Guan, Xinfu

    2013-01-01

    Glucagon-like peptides (GLP-1/2) are co-produced and highlighted as key modulators to improve glucose homeostasis and insulin sensitivity after bariatric surgery. However, it is unknown if CNS GLP-2 plays any physiological role in the control of glucose homeostasis and insulin sensitivity. We show that mice lacking GLP-2 receptor (GLP-2R) in POMC neurons display glucose intolerance and hepatic insulin resistance. GLP-2R activation in POMC neurons is required for GLP-2 to enhance insulin-mediated suppression of hepatic glucose production (HGP) and gluconeogenesis. GLP-2 directly modulates excitability of POMC neurons in GLP-2R- and PI3K-dependent manners. GLP-2 initiates GLP-2R-p85α interaction and facilitates PI3K-Akt-dependent FoxO1 nuclear exclusion in POMC neurons. Central GLP-2 suppresses basal HGP and enhances insulin sensitivity, which are abolished in POMC-p110α KO mice. Thus, CNS GLP-2 plays a key physiological role in the control of hepatic glucose production through activating PI3K-dependent modulation of membrane excitability and nuclear transcription of POMC neurons in the brain. PMID:23823479

  6. Central GLP-2 enhances hepatic insulin sensitivity via activating PI3K signaling in POMC neurons.

    Science.gov (United States)

    Shi, Xuemei; Zhou, Fuguo; Li, Xiaojie; Chang, Benny; Li, Depei; Wang, Yi; Tong, Qingchun; Xu, Yong; Fukuda, Makoto; Zhao, Jean J; Li, Defa; Burrin, Douglas G; Chan, Lawrence; Guan, Xinfu

    2013-07-02

    Glucagon-like peptides (GLP-1/GLP-2) are coproduced and highlighted as key modulators to improve glucose homeostasis and insulin sensitivity after bariatric surgery. However, it is unknown if CNS GLP-2 plays any physiological role in the control of glucose homeostasis and insulin sensitivity. We show that mice lacking GLP-2 receptor (GLP-2R) in POMC neurons display glucose intolerance and hepatic insulin resistance. GLP-2R activation in POMC neurons is required for GLP-2 to enhance insulin-mediated suppression of hepatic glucose production (HGP) and gluconeogenesis. GLP-2 directly modulates excitability of POMC neurons in GLP-2R- and PI3K-dependent manners. GLP-2 initiates GLP-2R-p85α interaction and facilitates PI3K-Akt-dependent FoxO1 nuclear exclusion in POMC neurons. Central GLP-2 suppresses basal HGP and enhances insulin sensitivity, which are abolished in POMC-p110α KO mice. Thus, CNS GLP-2 plays a key physiological role in the control of HGP through activating PI3K-dependent modulation of membrane excitability and nuclear transcription of POMC neurons in the brain. Copyright © 2013 Elsevier Inc. All rights reserved.

  7. Acute activation of GLP-1-expressing neurons promotes glucose homeostasis and insulin sensitivity.

    Science.gov (United States)

    Shi, Xuemei; Chacko, Shaji; Li, Feng; Li, Depei; Burrin, Douglas; Chan, Lawrence; Guan, Xinfu

    2017-11-01

    Glucagon-like peptides are co-released from enteroendocrine L cells in the gut and preproglucagon (PPG) neurons in the brainstem. PPG-derived GLP-1/2 are probably key neuroendocrine signals for the control of energy balance and glucose homeostasis. The objective of this study was to determine whether activation of PPG neurons per se modulates glucose homeostasis and insulin sensitivity in vivo. We generated glucagon (Gcg) promoter-driven Cre transgenic mice and injected excitatory hM3Dq-mCherry AAV into their brainstem NTS. We characterized the metabolic impact of PPG neuron activation on glucose homeostasis and insulin sensitivity using stable isotopic tracers coupled with hyperinsulinemic euglycemic clamp. We showed that after ip injection of clozapine N-oxide, Gcg-Cre lean mice transduced with hM3Dq in the brainstem NTS downregulated basal endogenous glucose production and enhanced glucose tolerance following ip glucose tolerance test. Moreover, acute activation of PPG neurons NTS enhanced whole-body insulin sensitivity as indicated by increased glucose infusion rate as well as augmented insulin-suppression of endogenous glucose production and gluconeogenesis. In contrast, insulin-stimulation of glucose disposal was not altered significantly. We conclude that acute activation of PPG neurons in the brainstem reduces basal glucose production, enhances intraperitoneal glucose tolerance, and augments hepatic insulin sensitivity, suggesting an important physiological role of PPG neurons-mediated circuitry in promoting glycemic control and insulin sensitivity. Copyright © 2017 The Authors. Published by Elsevier GmbH.. All rights reserved.

  8. Genetically encoded proton sensors reveal activity-dependent pH changes in neurons

    Directory of Open Access Journals (Sweden)

    Joseph Valentino Raimondo

    2012-05-01

    Full Text Available The regulation of hydrogen ion concentration (pH is fundamental to cell viability, metabolism and enzymatic function. Within the nervous system, the control of pH is also involved in diverse and dynamic processes including development, synaptic transmission and the control of network excitability. As pH affects neuronal activity, and can also itself be altered by neuronal activity, the existence of tools to accurately measure hydrogen ion fluctuations is important for understanding the role pH plays under physiological and pathological conditions. Outside of their use as a marker of synaptic release, genetically encoded pH sensors have not been utilised to study hydrogen ion fluxes associated with network activity. By combining whole-cell patch clamp with simultaneous two-photon or confocal imaging, we quantified the amplitude and time course of neuronal, intracellular, acidic transients evoked by epileptiform activity in two separate in vitro models of temporal lobe epilepsy. In doing so, we demonstrate the suitability of three genetically encoded pH sensors: deGFP4, E2GFP and Cl-sensor for investigating activity-dependent pH changes at the level of single neurons.

  9. Genetically encoded proton sensors reveal activity-dependent pH changes in neurons.

    Science.gov (United States)

    Raimondo, Joseph V; Irkle, Agnese; Wefelmeyer, Winnie; Newey, Sarah E; Akerman, Colin J

    2012-01-01

    The regulation of hydrogen ion concentration (pH) is fundamental to cell viability, metabolism, and enzymatic function. Within the nervous system, the control of pH is also involved in diverse and dynamic processes including development, synaptic transmission, and the control of network excitability. As pH affects neuronal activity, and can also itself be altered by neuronal activity, the existence of tools to accurately measure hydrogen ion fluctuations is important for understanding the role pH plays under physiological and pathological conditions. Outside of their use as a marker of synaptic release, genetically encoded pH sensors have not been utilized to study hydrogen ion fluxes associated with network activity. By combining whole-cell patch clamp with simultaneous two-photon or confocal imaging, we quantified the amplitude and time course of neuronal, intracellular, acidic transients evoked by epileptiform activity in two separate in vitro models of temporal lobe epilepsy. In doing so, we demonstrate the suitability of three genetically encoded pH sensors: deGFP4, E(2)GFP, and Cl-sensor for investigating activity-dependent pH changes at the level of single neurons.

  10. Adenosine A2A Receptor Modulates the Activity of Globus Pallidus Neurons in Rats

    Directory of Open Access Journals (Sweden)

    Hui-Ling Diao

    2017-11-01

    Full Text Available The globus pallidus is a central nucleus in the basal ganglia motor control circuit. Morphological studies have revealed the expression of adenosine A2A receptors in the globus pallidus. To determine the modulation of adenosine A2A receptors on the activity of pallidal neurons in both normal and parkinsonian rats, in vivo electrophysiological and behavioral tests were performed in the present study. The extracellular single unit recordings showed that micro-pressure administration of adenosine A2A receptor agonist, CGS21680, regulated the pallidal firing activity. GABAergic neurotransmission was involved in CGS21680-induced modulation of pallidal neurons via a PKA pathway. Furthermore, application of two adenosine A2A receptor antagonists, KW6002 or SCH442416, mainly increased the spontaneous firing of pallidal neurons, suggesting that endogenous adenosine system modulates the activity of pallidal neurons through adenosine A2A receptors. Finally, elevated body swing test (EBST showed that intrapallidal microinjection of adenosine A2A receptor agonist/antagonist induced ipsilateral/contralateral-biased swing, respectively. In addition, the electrophysiological and behavioral findings also revealed that activation of dopamine D2 receptors by quinpirole strengthened KW6002/SCH442416-induced excitation of pallidal activity. Co-application of quinpirole with KW6002 or SCH442416 alleviated biased swing in hemi-parkinsonian rats. Based on the present findings, we concluded that pallidal adenosine A2A receptors may be potentially useful in the treatment of Parkinson's disease.

  11. Engineering a light-activated caspase-3 for precise ablation of neurons in vivo.

    Science.gov (United States)

    Smart, Ashley D; Pache, Roland A; Thomsen, Nathan D; Kortemme, Tanja; Davis, Graeme W; Wells, James A

    2017-09-26

    The circuitry of the brain is characterized by cell heterogeneity, sprawling cellular anatomy, and astonishingly complex patterns of connectivity. Determining how complex neural circuits control behavior is a major challenge that is often approached using surgical, chemical, or transgenic approaches to ablate neurons. However, all these approaches suffer from a lack of precise spatial and temporal control. This drawback would be overcome if cellular ablation could be controlled with light. Cells are naturally and cleanly ablated through apoptosis due to the terminal activation of caspases. Here, we describe the engineering of a light-activated human caspase-3 (Caspase-LOV) by exploiting its natural spring-loaded activation mechanism through rational insertion of the light-sensitive LOV2 domain that expands upon illumination. We apply the light-activated caspase (Caspase-LOV) to study neurodegeneration in larval and adult Drosophila Using the tissue-specific expression system (UAS)-GAL4, we express Caspase-LOV specifically in three neuronal cell types: retinal, sensory, and motor neurons. Illumination of whole flies or specific tissues containing Caspase-LOV-induced cell death and allowed us to follow the time course and sequence of neurodegenerative events. For example, we find that global synchronous activation of caspase-3 drives degeneration with a different time-course and extent in sensory versus motor neurons. We believe the Caspase-LOV tool we engineered will have many other uses for neurobiologists and others for specific temporal and spatial ablation of cells in complex organisms.

  12. Bi-directional astrocytic regulation of neuronal activity within a network

    Directory of Open Access Journals (Sweden)

    Susan Yu Gordleeva

    2012-11-01

    Full Text Available The concept of a tripartite synapse holds that astrocytes can affect both the pre- and postsynaptic compartments through the Ca2+-dependent release of gliotransmitters. Because astrocytic Ca2+ transients usually last for a few seconds, we assumed that astrocytic regulation of synaptic transmission may also occur on the scale of seconds. Here, we considered the basic physiological functions of tripartite synapses and investigated astrocytic regulation at the level of neural network activity. The firing dynamics of individual neurons in a spontaneous firing network was described by the Hodgkin-Huxley model. The neurons received excitatory synaptic input driven by the Poisson spike train with variable frequency. The mean field concentration of the released neurotransmitter was used to describe the presynaptic dynamics. The amplitudes of the excitatory postsynaptic currents (PSCs obeyed the gamma distribution law. In our model, astrocytes depressed the presynaptic release and enhanced the postsynaptic currents. As a result, low frequency synaptic input was suppressed while high frequency input was amplified. The analysis of the neuron spiking frequency as an indicator of network activity revealed that tripartite synaptic transmission dramatically changed the local network operation compared to bipartite synapses. Specifically, the astrocytes supported homeostatic regulation of the network activity by increasing or decreasing firing of the neurons. Thus, the astrocyte activation may modulate a transition of neural network into bistable regime of activity with two stable firing levels and spontaneous transitions between them.

  13. Antihelminthic benzimidazoles are novel HIF activators that prevent oxidative neuronal death via binding to tubulin.

    Science.gov (United States)

    Aleyasin, Hossein; Karuppagounder, Saravanan S; Kumar, Amit; Sleiman, Sama; Basso, Manuela; Ma, Thong; Siddiq, Ambreena; Chinta, Shankar J; Brochier, Camille; Langley, Brett; Haskew-Layton, Renee; Bane, Susan L; Riggins, Gregory J; Gazaryan, Irina; Starkov, Anatoly A; Andersen, Julie K; Ratan, Rajiv R

    2015-01-10

    Pharmacological activation of the adaptive response to hypoxia is a therapeutic strategy of growing interest for neurological conditions, including stroke, Huntington's disease, and Parkinson's disease. We screened a drug library with known safety in humans using a hippocampal neuroblast line expressing a reporter of hypoxia-inducible factor (HIF)-dependent transcription. Our screen identified more than 40 compounds with the ability to induce hypoxia response element-driven luciferase activity as well or better than deferoxamine, a canonical activator of hypoxic adaptation. Among the chemical entities identified, the antihelminthic benzimidazoles represented one pharmacophore that appeared multiple times in our screen. Secondary assays confirmed that antihelminthics stabilized the transcriptional activator HIF-1α and induced expression of a known HIF target gene, p21(cip1/waf1), in post-mitotic cortical neurons. The on-target effect of these agents in stimulating hypoxic signaling was binding to free tubulin. Moreover, antihelminthic benzimidazoles also abrogated oxidative stress-induced death in vitro, and this on-target effect also involves binding to free tubulin. These studies demonstrate that tubulin-binding drugs can activate a component of the hypoxic adaptive response, specifically the stabilization of HIF-1α and its downstream targets. Tubulin-binding drugs, including antihelminthic benzimidazoles, also abrogate oxidative neuronal death in primary neurons. Given their safety in humans and known ability to penetrate into the central nervous system, antihelminthic benzimidazoles may be considered viable candidates for treating diseases associated with oxidative neuronal death, including stroke.

  14. Optical imaging of neuronal activity and visualization of fine neural structures in non-desheathed nervous systems.

    Directory of Open Access Journals (Sweden)

    Christopher John Goldsmith

    Full Text Available Locating circuit neurons and recording from them with single-cell resolution is a prerequisite for studying neural circuits. Determining neuron location can be challenging even in small nervous systems because neurons are densely packed, found in different layers, and are often covered by ganglion and nerve sheaths that impede access for recording electrodes and neuronal markers. We revisited the voltage-sensitive dye RH795 for its ability to stain and record neurons through the ganglion sheath. Bath-application of RH795 stained neuronal membranes in cricket, earthworm and crab ganglia without removing the ganglion sheath, revealing neuron cell body locations in different ganglion layers. Using the pyloric and gastric mill central pattern generating neurons in the stomatogastric ganglion (STG of the crab, Cancer borealis, we found that RH795 permeated the ganglion without major residue in the sheath and brightly stained somatic, axonal and dendritic membranes. Visibility improved significantly in comparison to unstained ganglia, allowing the identification of somata location and number of most STG neurons. RH795 also stained axons and varicosities in non-desheathed nerves, and it revealed the location of sensory cell bodies in peripheral nerves. Importantly, the spike activity of the sensory neuron AGR, which influences the STG motor patterns, remained unaffected by RH795, while desheathing caused significant changes in AGR activity. With respect to recording neural activity, RH795 allowed us to optically record membrane potential changes of sub-sheath neuronal membranes without impairing sensory activity. The signal-to-noise ratio was comparable with that previously observed in desheathed preparations and sufficiently high to identify neurons in single-sweep recordings and synaptic events after spike-triggered averaging. In conclusion, RH795 enabled staining and optical recording of neurons through the ganglion sheath and is therefore both a

  15. Effect of acute stretch injury on action potential and network activity of rat neocortical neurons in culture.

    Science.gov (United States)

    Magou, George C; Pfister, Bryan J; Berlin, Joshua R

    2015-10-22

    The basis for acute seizures following traumatic brain injury (TBI) remains unclear. Animal models of TBI have revealed acute hyperexcitablility in cortical neurons that could underlie seizure activity, but studying initiating events causing hyperexcitability is difficult in these models. In vitro models of stretch injury with cultured cortical neurons, a surrogate for TBI, allow facile investigation of cellular changes after injury but they have only demonstrated post-injury hypoexcitability. The goal of this study was to determine if neuronal hyperexcitability could be triggered by in vitro stretch injury. Controlled uniaxial stretch injury was delivered to a spatially delimited region of a spontaneously active network of cultured rat cortical neurons, yielding a region of stretch-injured neurons and adjacent regions of non-stretched neurons that did not directly experience stretch injury. Spontaneous electrical activity was measured in non-stretched and stretch-injured neurons, and in control neuronal networks not subjected to stretch injury. Non-stretched neurons in stretch-injured cultures displayed a three-fold increase in action potential firing rate and bursting activity 30-60 min post-injury. Stretch-injured neurons, however, displayed dramatically lower rates of action potential firing and bursting. These results demonstrate that acute hyperexcitability can be observed in non-stretched neurons located in regions adjacent to the site of stretch injury, consistent with reports that seizure activity can arise from regions surrounding the site of localized brain injury. Thus, this in vitro procedure for localized neuronal stretch injury may provide a model to study the earliest cellular changes in neuronal function associated with acute post-traumatic seizures. Copyright © 2015. Published by Elsevier B.V.

  16. Bone conducted vibration selectively activates irregular primary otolithic vestibular neurons in the guinea pig.

    Science.gov (United States)

    Curthoys, Ian S; Kim, Juno; McPhedran, Samara K; Camp, Aaron J

    2006-11-01

    The main objective of this study was to determine whether bone-conducted vibration (BCV) is equally effective in activating both semicircular canal and otolith afferents in the guinea pig or whether there is preferential activation of one of these classes of vestibular afferents. To answer this question a large number (346) of single primary vestibular neurons were recorded extracellularly in anesthetized guinea pigs and were identified by their location in the vestibular nerve and classed as regular or irregular on the basis of the variability of their spontaneous discharge. If a neuron responded to angular acceleration it was classed as a semicircular canal neuron, if it responded to maintained roll or pitch tilts it was classified as an otolith neuron. Each neuron was then tested by BCV stimuli-either clicks, continuous pure tones (200-1,500 Hz) or short tone bursts (500 Hz lasting 7 ms)-delivered by a B-71 clinical bone-conduction oscillator cemented to the guinea pig's skull. All stimulus intensities were referred to that animal's own auditory brainstem response (ABR) threshold to BCV clicks, and the maximum intensity used was within the animal's physiological range and was usually around 70 dB above BCV threshold. In addition two sensitive single axis linear accelerometers cemented to the skull gave absolute values of the stimulus acceleration in the rostro-caudal direction. The criterion for a neuron being classed as activated was an audible, stimulus-locked increase in firing rate (a 10% change was easily detectable) in response to the BCV stimulus. At the stimulus levels used in this study, semicircular canal neurons, both regular and irregular, were insensitive to BCV stimuli and very few responded: only nine of 189 semicircular canal neurons tested (4.7%) showed a detectable increase in firing in response to BCV stimuli up to the maximum 2 V peak-to-peak level we delivered to the B-71 oscillator (which produced a peak-to-peak skull acceleration of around

  17. Effect of the peptide Tat(49-57) on the bio-distribution and similar radiopharmaceuticals dosimetry of the bombesin

    International Nuclear Information System (INIS)

    Santos C, C. L.

    2011-01-01

    The gastrin-releasing peptide receptor (GRP-r) is over-expressed in prostate and breast cancer. 99m Tc-Bombesin ( 99m Tc-Bn) has been reported as a radiopharmaceutical with specific cell GRP-r binding. The HIV Tat(49-57)-derived peptide has been used to deliver a large variety of molecules to cell nuclei. New hybrid radiopharmaceuticals of type 99m Tc-N 2 S 2 -Tat(49-57)-Lys 3 -Bn ( 99m Tc-Tat-Bn) and 188 Re-N 2 S 2 -Tat(49-57)-Lys 3 -Bn ( 188 Re-Tat-Bn), would increase cell uptake and internalized in cancer cell nuclei could act as an effective system of targeted radiotherapy using Auger and internal conversion (I C) electron emissions near DNA. The aim of this research was to prepare and assess in vitro and in vivo uptake kinetics in cancer cells of 99m Tc/ 188 Re-Tat-Bn and the in vitro nucleus and cytoplasm internalization kinetics in GRP receptor-positive cancer cells as well as to evaluate the subcellular-level radiation absorbed dose associated with the observed effect on cancer cell DNA proliferation. Structures of N 2 S 2 -Tat-Bn and Tc/Re(O)N 2 S 2 -Tat-Bn were calculated by an Mm procedure. 99m Tc-Tat-Bn and 188 Re-Tat-Bn were synthesized and stability studies carried out by HPLC and I TLC-Sg analyses in serum and cysteine solutions. In vitro internalization was tested using human prostate cancer Pc 3 cells and breast carcinoma cell lines MDA-Mb 231 and MCF 7. Nuclei from cells were isolated using a nuclear extraction kit. Total disintegrations in each subcellular compartment were calculated by integration of experimental time activity kinetic curves. Nucleus internalization was corroborated by con focal microscopy images using immunofluorescent labelled Tat-Bn. Biodistribution was determined in Pc 3 tumor-bearing nude mice. The Penelope code was used to simulate and calculate the absorbed dose by contribution of β, Auger and I C electrons in the cytoplasm and nucleus using geometric models built from immunofluorescent cell images. A cell proliferation

  18. Nav 1.8-null mice show stimulus-dependent deficits in spinal neuronal activity

    Directory of Open Access Journals (Sweden)

    Wood John N

    2006-02-01

    Full Text Available Abstract Background The voltage gated sodium channel Nav 1.8 has a highly restricted expression pattern to predominantly nociceptive peripheral sensory neurones. Behaviourally Nav 1.8-null mice show an increased acute pain threshold to noxious mechanical pressure and also deficits in inflammatory and visceral, but not neuropathic pain. Here we have made in vivo electrophysiology recordings of dorsal horn neurones in intact anaesthetised Nav 1.8-null mice, in response to a wide range of stimuli to further the understanding of the functional roles of Nav 1.8 in pain transmission from the periphery to the spinal cord. Results Nav 1.8-null mice showed marked deficits in the coding by dorsal horn neurones to mechanical, but not thermal, -evoked responses over the non-noxious and noxious range compared to littermate controls. Additionally, responses evoked to other stimulus modalities were also significantly reduced in Nav 1.8-null mice where the reduction observed to pinch > brush. The occurrence of ongoing spontaneous neuronal activity was significantly less in mice lacking Nav 1.8 compared to control. No difference was observed between groups in the evoked activity to electrical activity of the peripheral receptive field. Conclusion This study demonstrates that deletion of the sodium channel Nav 1.8 results in stimulus-dependent deficits in the dorsal horn neuronal coding to mechanical, but not thermal stimuli applied to the neuronal peripheral receptive field. This implies that Nav 1.8 is either responsible for, or associated with proteins involved in mechanosensation.

  19. Interaction of the phospholipid scramblase 1 with HIV-1 Tat results in the repression of Tat-dependent transcription

    International Nuclear Information System (INIS)

    Kusano, Shuichi; Eizuru, Yoshito

    2013-01-01

    Highlights: •PLSCR1 specifically interacted with HIV-1 Tat in vitro and in vivo. •PLSCR1 repressed Tat-dependent transactivation of the HIV-1 LTR. •Suppression of PLSCR1 expression enhanced the levels of HIV-1 transcripts. •PLSCR1 reduced the nuclear localization of Tat. -- Abstract: Human phospholipid scramblase 1 (PLSCR1) is an interferon (IFN)-stimulated gene and possesses an IFN-mediated antiviral function. We show here that PLSCR1 directly interacts with human immunodeficiency virus type-1 (HIV-1) Tat. This interaction occurs both in vitro and in vivo through amino acids 160–250 of PLSCR1. Overexpression of PLSCR1 efficiently represses the Tat-dependent transactivation of the HIV-1 long terminal repeat (LTR) and reduces the nuclear translocation of Tat. In addition, shRNA-mediated suppression of endogenous PLSCR1 expression enhances the levels of gag mRNA in an HIV-1-infected T-cell line. These findings indicate that PLSCR1 negatively regulates the Tat-dependent transactivation of the HIV-1 LTR during HIV-1 infection

  20. Human embryonic stem cell-derived neurons adopt and regulate the activity of an established neural network

    Science.gov (United States)

    Weick, Jason P.; Liu, Yan; Zhang, Su-Chun

    2011-01-01

    Whether hESC-derived neurons can fully integrate with and functionally regulate an existing neural network remains unknown. Here, we demonstrate that hESC-derived neurons receive unitary postsynaptic currents both in vitro and in vivo and adopt the rhythmic firing behavior of mouse cortical networks via synaptic integration. Optical stimulation of hESC-derived neurons expressing Channelrhodopsin-2 elicited both inhibitory and excitatory postsynaptic currents and triggered network bursting in mouse neurons. Furthermore, light stimulation of hESC-derived neurons transplanted to the hippocampus of adult mice triggered postsynaptic currents in host pyramidal neurons in acute slice preparations. Thus, hESC-derived neurons can participate in and modulate neural network activity through functional synaptic integration, suggesting they are capable of contributing to neural network information processing both in vitro and in vivo. PMID:22106298

  1. Fragile X Mental Retardation Protein (FMRP) controls diacylglycerol kinase activity in neurons.

    Science.gov (United States)

    Tabet, Ricardos; Moutin, Enora; Becker, Jérôme A J; Heintz, Dimitri; Fouillen, Laetitia; Flatter, Eric; Krężel, Wojciech; Alunni, Violaine; Koebel, Pascale; Dembélé, Doulaye; Tassone, Flora; Bardoni, Barbara; Mandel, Jean-Louis; Vitale, Nicolas; Muller, Dominique; Le Merrer, Julie; Moine, Hervé

    2016-06-28

    Fragile X syndrome (FXS) is caused by the absence of the Fragile X Mental Retardation Protein (FMRP) in neurons. In the mouse, the lack of FMRP is associated with an excessive translation of hundreds of neuronal proteins, notably including postsynaptic proteins. This local protein synthesis deregulation is proposed to underlie the observed defects of glutamatergic synapse maturation and function and to affect preferentially the hundreds of mRNA species that were reported to bind to FMRP. How FMRP impacts synaptic protein translation and which mRNAs are most important for the pathology remain unclear. Here we show by cross-linking immunoprecipitation in cortical neurons that FMRP is mostly associated with one unique mRNA: diacylglycerol kinase kappa (Dgkκ), a master regulator that controls the switch between diacylglycerol and phosphatidic acid signaling pathways. The absence of FMRP in neurons abolishes group 1 metabotropic glutamate receptor-dependent DGK activity combined with a loss of Dgkκ expression. The reduction of Dgkκ in neurons is sufficient to cause dendritic spine abnormalities, synaptic plasticity alterations, and behavior disorders similar to those observed in the FXS mouse model. Overexpression of Dgkκ in neurons is able to rescue the dendritic spine defects of the Fragile X Mental Retardation 1 gene KO neurons. Together, these data suggest that Dgkκ deregulation contributes to FXS pathology and support a model where FMRP, by controlling the translation of Dgkκ, indirectly controls synaptic proteins translation and membrane properties by impacting lipid signaling in dendritic spine.

  2. Dendritic calcium activity precedes inspiratory bursts in preBotzinger complex neurons

    DEFF Research Database (Denmark)

    Del Negro, Christopher A; Hayes, John A; Rekling, Jens C

    2011-01-01

    to evoke a Ca(2+)-activated inward current that contributes to inspiratory burst generation. We measured Ca(2+) transients by two-photon imaging dendrites while recording neuronal somata electrophysiologically. Dendritic Ca(2+) accumulation frequently precedes inspiratory bursts, particularly at recording...

  3. Endogenous fatty acid ethanolamides suppress nicotine-induced activation of mesolimbic dopamine neurons through nuclear receptors.

    Science.gov (United States)

    Melis, Miriam; Pillolla, Giuliano; Luchicchi, Antonio; Muntoni, Anna Lisa; Yasar, Sevil; Goldberg, Steven R; Pistis, Marco

    2008-12-17

    Nicotine stimulates the activity of mesolimbic dopamine neurons, which is believed to mediate the rewarding and addictive properties of tobacco use. Accumulating evidence suggests that the endocannabinoid system might play a major role in neuronal mechanisms underlying the rewarding properties of drugs of abuse, including nicotine. Here, we investigated the modulation of nicotine effects by the endocannabinoid system on dopamine neurons in the ventral tegmental area with electrophysiological techniques in vivo and in vitro. We discovered that pharmacological inhibition of fatty acid amide hydrolase (FAAH), the enzyme that catabolizes fatty acid ethanolamides, among which the endocannabinoid anandamide (AEA) is the best known, suppressed nicotine-induced excitation of dopamine cells. Importantly, this effect was mimicked by the administration of the FAAH substrates oleoylethanolamide (OEA) and palmitoylethanolamide (PEA), but not methanandamide, the hydrolysis resistant analog of AEA. OEA and PEA are naturally occurring lipid signaling molecules structurally related to AEA, but devoid of affinity for cannabinoid receptors. They blocked the effects of nicotine by activation of the peroxisome proliferator-activated receptor-alpha (PPAR-alpha), a nuclear receptor transcription factor involved in several aspects of lipid metabolism and energy balance. Activation of PPAR-alpha triggered a nongenomic stimulation of tyrosine kinases, which might lead to phosphorylation and negative regulation of neuronal nicotinic acetylcholine receptors. These data indicate for the first time that the anorexic lipids OEA and PEA possess neuromodulatory properties as endogenous ligands of PPAR-alpha in the brain and provide a potential new target for the treatment of nicotine addiction.

  4. Neuronal targeting, internalization, and biological activity of a recombinant atoxic derivative of botulinum neurotoxin A

    Science.gov (United States)

    Botulinum neurotoxins (BoNT) have the unique capacity to cross epithelial barriers, target neuromuscular junctions, and translocate active metalloprotease component to the cytosol of motor neurons. We have taken advantage of the molecular carriers responsible for this trafficking to create a family ...

  5. Neuronal activation by mucosal biopsy supernatants from irritable bowel syndrome patients is linked to visceral sensitivity

    NARCIS (Netherlands)

    Buhner, Sabine; Braak, Breg; Li, Qin; Kugler, Eva Maria; Klooker, Tamira; Wouters, Mira; Donovan, Jemma; Vignali, Sheila; Mazzuoli-Weber, Gemma; Grundy, David; Boeckxstaens, Guy; Schemann, Michael

    2014-01-01

    Based on the discomfort/pain threshold during rectal distension, irritable bowel syndrome (IBS) patients may be subtyped as normo- or hypersensitive. We previously showed that mucosal biopsy supernatants from IBS patients activated enteric and visceral afferent neurons. We tested the hypothesis that

  6. Effects of the TAT peptide orientation and relative location on the protein transduction efficiency.

    Science.gov (United States)

    Guo, Qingguo; Zhao, Guojie; Hao, Fengjin; Guan, Yifu

    2012-05-01

    To understand the protein transduction domain (PTD)-mediated protein transduction behavior and to explore its potential in delivering biopharmaceutic drugs, we prepared four TAT-EGFP conjugates: TAT(+)-EGFP, TAT(-)-EGFP, EGFP-TAT(+) and EGFP-TAT(-), where TAT(+) and TAT(-) represent the original and the reversed TAT sequence, respectively. These four TAT-EGFP conjugates were incubated with HeLa and PC12 cells for in vitro study as well as injected intraperitoneally to mice for in vivo study. Flow cytometric results showed that four TAT-EGFP conjugates were able to traverse HeLa and PC12 cells with almost equal transduction efficiency. The in vivo study showed that the TAT-EGFP conjugates could be delivered into different organs of mice with different transduction capabilities. Bioinformatic analyses and CD spectroscopic data revealed that the TAT peptide has no defined secondary structure, and conjugating the TAT peptide to the EGFP cargo protein would not alter the native structure and the function of the EGFP protein. These results conclude that the sequence orientation, the spatial structure, and the relative location of the TAT peptide have much less effect on the TAT-mediated protein transduction. Thus, the TAT-fused conjugates could be constructed in more convenient and flexible formats for a wide range of biopharmaceutical applications. © 2011 John Wiley & Sons A/S.

  7. Nerve Growth Factor Gene Therapy Activates Neuronal Responses in Alzheimer’s Disease

    Science.gov (United States)

    Tuszynski, Mark H.; Yang, Jennifer H.; Barba, David; U, H S.; Bakay, Roy; Pay, Mary M.; Masliah, Eliezer; Conner, James M.; Kobalka, Peter; Roy, Subhojit; Nagahara, Alan H.

    2016-01-01

    IMPORTANCE Alzheimer’s disease (AD) is the most common neurodegenerative disorder, and lacks effective disease modifying therapies. In 2001 we initiated a clinical trial of Nerve Growth Factor (NGF) gene therapy in AD, the first effort at gene delivery in an adult neurodegenerative disorder. This program aimed to determine whether a nervous system growth factor prevents or reduces cholinergic neuronal degeneration in AD patients. We present post-mortem findings in 10 subjects with survival times ranging from 1 to 10 years post-treatment. OBJECTIVE To determine whether degenerating neurons in AD retain an ability to respond to a nervous system growth factor delivered after disease onset. DESIGN, SETTING, AND PARTICIPANTS 10 patients with early AD underwent NGF gene therapy using either ex vivo or in vivo gene transfer. The brains of all eight patients in the first Phase 1 ex vivo trial and two patients in a subsequent Phase 1 in vivo trial were examined. MAIN OUTCOME MEASURES Brains were immunolabeled to evaluate in vivo gene expression, cholinergic neuronal responses to NGF, and activation of NGF-related cell signaling. In two cases, NGF protein levels were measured by ELISA. RESULTS Degenerating neurons in the AD brain respond to NGF. All patients exhibited a trophic response to NGF, in the form of axonal sprouting toward the NGF source. Comparing treated and non-treated sides of the brain in three patients that underwent unilateral gene transfer, cholinergic neuronal hypertrophy occurred on the NGF-treated side (P>0.05). Activation of cellular signaling and functional markers were present in two patients that underwent AAV2-mediated NGF gene transfer. Neurons exhibiting tau pathology as well as neurons free of tau expressed NGF, indicating that degenerating cells can be infected with therapeutic genes with resulting activation of cell signaling. No adverse pathological effects related to NGF were observed. CONCLUSIONS AND RELEVANCE These findings indicate that

  8. Nerve Growth Factor Gene Therapy: Activation of Neuronal Responses in Alzheimer Disease.

    Science.gov (United States)

    Tuszynski, Mark H; Yang, Jennifer H; Barba, David; U, Hoi-Sang; Bakay, Roy A E; Pay, Mary M; Masliah, Eliezer; Conner, James M; Kobalka, Peter; Roy, Subhojit; Nagahara, Alan H

    2015-10-01

    Alzheimer disease (AD) is the most common neurodegenerative disorder and lacks effective disease-modifying therapies. In 2001, we initiated a clinical trial of nerve growth factor (NGF) gene therapy in AD, the first effort at gene delivery in an adult neurodegenerative disorder. This program aimed to determine whether a nervous system growth factor prevents or reduces cholinergic neuronal degeneration in patients with AD. We present postmortem findings in 10 patients with survival times ranging from 1 to 10 years after treatment. To determine whether degenerating neurons in AD retain an ability to respond to a nervous system growth factor delivered after disease onset. Patients in this anatomicopathological study were enrolled in clinical trials from March 2001 to October 2012 at the University of California, San Diego, Medical Center in La Jolla. Ten patients with early AD underwent NGF gene therapy using ex vivo or in vivo gene transfer. The brains of all 8 patients in the first phase 1 ex vivo trial and of 2 patients in a subsequent phase 1 in vivo trial were examined. Brains were immunolabeled to evaluate in vivo gene expression, cholinergic neuronal responses to NGF, and activation of NGF-related cell signaling. In 2 patients, NGF protein levels were measured by enzyme-linked immunosorbent assay. Among 10 patients, degenerating neurons in the AD brain responded to NGF. All patients exhibited a trophic response to NGF in the form of axonal sprouting toward the NGF source. Comparing treated and nontreated sides of the brain in 3 patients who underwent unilateral gene transfer, cholinergic neuronal hypertrophy occurred on the NGF-treated side (P < .05). Activation of cellular signaling and functional markers was present in 2 patients who underwent adeno-associated viral vectors (serotype 2)-mediated NGF gene transfer. Neurons exhibiting tau pathology and neurons free of tau expressed NGF, indicating that degenerating cells can be infected with therapeutic

  9. Phrenic long-term facilitation requires PKCθ activity within phrenic motor neurons.

    Science.gov (United States)

    Devinney, Michael J; Fields, Daryl P; Huxtable, Adrianne G; Peterson, Timothy J; Dale, Erica A; Mitchell, Gordon S

    2015-05-27

    Acute intermittent hypoxia (AIH) induces a form of spinal motor plasticity known as phrenic long-term facilitation (pLTF); pLTF is a prolonged increase in phrenic motor output after AIH has ended. In anesthetized rats, we demonstrate that pLTF requires activity of the novel PKC isoform, PKCθ, and that the relevant PKCθ is within phrenic motor neurons. Whereas spinal PKCθ inhibitors block pLTF, inhibitors targeting other PKC isoforms do not. PKCθ is highly expressed in phrenic motor neurons, and PKCθ knockdown with intrapleural siRNAs abolishes pLTF. Intrapleural siRNAs targeting PKCζ, an atypical PKC isoform expressed in phrenic motor neurons that underlies a distinct form of phrenic motor plasticity, does not affect pLTF. Thus, PKCθ plays a critical role in spinal AIH-induced respiratory motor plasticity, and the relevant PKCθ is localized within phrenic motor neurons. Intrapleural siRNA delivery has considerable potential as a therapeutic tool to selectively manipulate plasticity in vital respiratory motor neurons. Copyright © 2015 the authors 0270-6474/15/358107-11$15.00/0.

  10. Superficial dorsal horn neurons with double spike activity in the rat.

    Science.gov (United States)

    Rojas-Piloni, Gerardo; Dickenson, Anthony H; Condés-Lara, Miguel

    2007-05-29

    Superficial dorsal horn neurons promote the transfer of nociceptive information from the periphery to supraspinal structures. The membrane and discharge properties of spinal cord neurons can alter the reliability of peripheral signals. In this paper, we analyze the location and response properties of a particular class of dorsal horn neurons that exhibits double spike discharge with a very short interspike interval (2.01+/-0.11 ms). These neurons receive nociceptive C-fiber input and are located in laminae I-II. Double spikes are generated spontaneously or by depolarizing current injection (interval of 2.37+/-0.22). Cells presenting double spike (interval 2.28+/-0.11) increased the firing rate by electrical noxious stimulation, as well as, in the first minutes after carrageenan injection into their receptive field. Carrageenan is a polysaccharide soluble in water and it is used for producing an experimental model of semi-chronic pain. In the present study carrageenan also produces an increase in the interval between double spikes and then, reduced their occurrence after 5-10 min. The results suggest that double spikes are due to intrinsic membrane properties and that their frequency is related to C-fiber nociceptive activity. The present work shows evidence that double spikes in superficial spinal cord neurones are related to the nociceptive stimulation, and they are possibly part of an acute pain-control mechanism.

  11. Whole-Brain Mapping of Neuronal Activity in the Learned Helplessness Model of Depression.

    Science.gov (United States)

    Kim, Yongsoo; Perova, Zinaida; Mirrione, Martine M; Pradhan, Kith; Henn, Fritz A; Shea, Stephen; Osten, Pavel; Li, Bo

    2016-01-01

    Some individuals are resilient, whereas others succumb to despair in repeated stressful situations. The neurobiological mechanisms underlying such divergent behavioral responses remain unclear. Here, we employed an automated method for mapping neuronal activity in search of signatures of stress responses in the entire mouse brain. We used serial two-photon tomography to detect expression of c-FosGFP - a marker of neuronal activation - in c-fosGFP transgenic mice subjected to the learned helplessness (LH) procedure, a widely used model of stress-induced depression-like phenotype in laboratory animals. We found that mice showing "helpless" behavior had an overall brain-wide reduction in the level of neuronal activation compared with mice showing "resilient" behavior, with the exception of a few brain areas, including the locus coeruleus, that were more activated in the helpless mice. In addition, the helpless mice showed a strong trend of having higher similarity in whole-brain activity profile among individuals, suggesting that helplessness is represented by a more stereotypic brain-wide activation pattern. This latter effect was confirmed in rats subjected to the LH procedure, using 2-deoxy-2[18F]fluoro-D-glucose positron emission tomography to assess neural activity. Our findings reveal distinct brain activity markings that correlate with adaptive and maladaptive behavioral responses to stress, and provide a framework for further studies investigating the contribution of specific brain regions to maladaptive stress responses.

  12. Whole-brain mapping of neuronal activity in the learned helplessness model of depression

    Directory of Open Access Journals (Sweden)

    Yongsoo eKim

    2016-02-01

    Full Text Available Some individuals are resilient, whereas others succumb to despair in repeated stressful situations. The neurobiological mechanisms underlying such divergent behavioral responses remain unclear. Here, we employed an automated method for mapping neuronal activity in search of signatures of stress responses in the entire mouse brain. We used serial two-photon tomography to detect expression of c-FosGFP – a marker of neuronal activation – in c-fosGFP transgenic mice subjected to the learned helplessness (LH procedure, a widely used model of stress-induced depression-like phenotype in laboratory animals. We found that mice showing helpless behavior had an overall brain-wide reduction in the level of neuronal activation compared with mice showing resilient behavior, with the exception of a few brain areas, including the locus coeruleus, that were more activated in the helpless mice. In addition, the helpless mice showed a strong trend of having higher similarity in whole brain activity profile among individuals, suggesting that helplessness is represented by a more stereotypic brain-wide activation pattern. This latter effect was confirmed in rats subjected to the LH procedure, using 2-deoxy-2[18F]fluoro-D-glucose positron emission tomography to assess neural activity. Our findings reveal distinct brain activity markings that correlate with adaptive and maladaptive behavioral responses to stress, and provide a framework for further studies investigating the contribution of specific brain regions to maladaptive stress responses.

  13. [Local GABA-ergic modulation of serotonergic neuron activity in the nucleus raphe magnus].

    Science.gov (United States)

    Iniushkin, A N; Merkulova, N A; Orlova, A O; Iniushkina, E M

    2009-07-01

    In voltage-clamp experimental on slices of the rat brainstem the effects of 5-HT and GABA on serotonergic neurons of nucleus raphe magnus were investigated. Local applications of 5-HT induced an increase in IPCSs frequency and amplitude in 45% of serotonergic cells. The effect suppressed by the blocker of fast sodium channels tetradotoxin. Antagonist of GABA receptor gabazine blocked IPSCs in neurons both sensitive and non-sensitive to 5-HT action. Applications of GABA induced a membrane current (I(GABA)), which was completely blocked by gabazine. The data suggest self-control of the activity of serotonergic neurons in nucleus raphe magnus by negative feedback loop via local GABAergic interneurons.

  14. Activity strengths of cortical glutamatergic and GABAergic neurons are correlated with transgenerational inheritance of learning ability.

    Science.gov (United States)

    Liu, Yulong; Ge, Rongjing; Zhao, Xin; Guo, Rui; Huang, Li; Zhao, Shidi; Guan, Sudong; Lu, Wei; Cui, Shan; Wang, Shirlene; Wang, Jin-Hui

    2017-12-22

    The capabilities of learning and memory in parents are presumably transmitted to their offsprings, in which genetic codes and epigenetic regulations are thought as molecular bases. As neural plasticity occurs during memory formation as cellular mechanism, we aim to examine the correlation of activity strengths at cortical glutamatergic and GABAergic neurons to the transgenerational inheritance of learning ability. In a mouse model of associative learning, paired whisker and odor stimulations led to odorant-induced whisker motion, whose onset appeared fast (high learning efficiency, HLE) or slow (low learning efficiency, LLE). HLE male and female mice, HLE female and LLE male mice as well as HLE male and LLE female mice were cross-mated to have their first generation of offsprings, filials (F1). The onset of odorant-induced whisker motion appeared a sequence of high-to-low efficiency in three groups of F1 mice that were from HLE male and female mice, HLE female and LLE male mice as well as HLE male and LLE female mice. Activities related to glutamatergic neurons in barrel cortices appeared a sequence of high-to-low strength in these F1 mice from HLE male and female mice, HLE female and LLE male mice as well as HLE male and LLE female mice. Activities related to GABAergic neurons in barrel cortices appeared a sequence of low-to-high strength in these F1 mice from HLE male and female mice, HLE female and LLE male mice as well as HLE male and LLE female mice. Neuronal activity strength was linearly correlated to learning efficiency among three groups. Thus, the coordinated activities at glutamatergic and GABAergic neurons may constitute the cellular basis for the transgenerational inheritance of learning ability.

  15. A sodium afterdepolarization in rat superior colliculus neurons and its contribution to population activity.

    Science.gov (United States)

    Ghitani, Nima; Bayguinov, Peter O; Basso, Michele A; Jackson, Meyer B

    2016-07-01

    The mammalian superior colliculus (SC) is a midbrain structure that integrates multimodal sensory inputs and computes commands to initiate rapid eye movements. SC neurons burst with the sudden onset of a visual stimulus, followed by persistent activity that may underlie shifts of attention and decision making. Experiments in vitro suggest that circuit reverberations play a role in the burst activity in the SC, but the origin of persistent activity is unclear. In the present study we characterized an afterdepolarization (ADP) that follows action potentials in slices of rat SC. Population responses seen with voltage-sensitive dye imaging consisted of rapid spikes followed immediately by a second distinct depolarization of lower amplitude and longer duration. Patch-clamp recordings showed qualitatively similar behavior: in nearly all neurons throughout the SC, rapid spikes were followed by an ADP. Ionic and pharmacological manipulations along with experiments with current and voltage steps indicated that the ADP of SC neurons arises from Na(+) current that either persists or resurges following Na(+) channel inactivation at the end of an action potential. Comparisons of pharmacological properties and frequency dependence revealed a clear parallel between patch-clamp recordings and voltage imaging experiments, indicating a common underlying membrane mechanism for the ADP in both single neurons and populations. The ADP can initiate repetitive spiking at intervals consistent with the frequency of persistent activity in the SC. These results indicate that SC neurons have intrinsic membrane properties that can contribute to electrical activity that underlies shifts of attention and decision making. Copyright © 2016 the American Physiological Society.

  16. [CHANGES IN THE NUMBER OF NEURONS IN THE MOTOR CORTEX OF RATS AND THEIR LOCOMOTOR ACTIVITY IN THE AGE ASPECT].

    Science.gov (United States)

    Piavchenko, G A; Shmarkova, L I; Nozdrin, V I

    2015-01-01

    Using Laboras hardware-software complex, which is a system of automatic registration of behavioral reactions, the locomotor activity 1-, 8- and 16-month-old male rats (12 animals in each group) was recorded followed by counting the number of neuron cell bodies of in the layer V of the motor cortex in Nissl stained slides. It was found that the number of neurons in the motor cortex varied in different age groups. Maximal number of neurons was observed in 8-month-old animals. Motor activity was found to correlate with the number of neurons.

  17. Interleukin 6 modulates acetylcholinesterase activity of brain neurons

    International Nuclear Information System (INIS)

    Clarencon, D.; Multon, E.; Galonnier, M.; Estrade, M.; Fournier, C.; Mathieu, J.; Mestries, J.C.; Testylier, G.; Fatome, M.

    1995-01-01

    Classically, radiation injuries results in a peripheral inflammatory process, and we have previously observed an early systemic interleukin 6 (IL-6) release following whole-body irradiation. Besides, we have demonstrated an early decrease of rat or primate brain acetylcholinesterase (AChE) activity a gamma exposure. The object of the present study is to find possible IL-6 systemic effects on the brain AChE activity. We show that, though intravenous (i.v.) or intra-cerebro-ventricular (ICV) injection of IL-6 can induce a drop in rat brain AChE activity, this cytokine induces only a slight decrease of the AChE release in cultured brain cells. (author)

  18. Adrenergic receptors inhibit TRPV1 activity in the dorsal root ganglion neurons of rats.

    Science.gov (United States)

    Matsushita, Yumi; Manabe, Miki; Kitamura, Naoki; Shibuya, Izumi

    2018-01-01

    Transient receptor potential vanilloid type 1 (TRPV1) is a polymodal receptor channel that responds to multiple types of stimuli, such as heat, acid, mechanical pressure and some vanilloids. Capsaicin is the most commonly used vanilloid to stimulate TRPV1. TRPV1 channels are expressed in dorsal root ganglion neurons that extend to Aδ- and C-fibers and have a role in the transduction of noxious inputs to the skin into the electrical signals of the sensory nerve. Although noradrenergic nervous systems, including the descending antinociceptive system and the sympathetic nervous system, are known to modulate pain sensation, the functional association between TRPV1 and noradrenaline in primary sensory neurons has rarely been examined. In the present study, we examined the effects of noradrenaline on capsaicin-evoked currents in cultured dorsal root ganglion neurons of the rat by the whole-cell voltage clamp method. Noradrenaline at concentrations higher than 0.1 pM significantly reduced the amplitudes of the inward capsaicin currents recorded at -60 mV holding potential. This inhibitory action was reversed by either yohimbine (an α2 antagonist, 10 nM) or propranolol (a β antagonist, 10 nM). The α2 agonists, clonidine (1 pM) and dexmedetomidine (1 pM) inhibited capsaicin currents, and yohimbine (1 nM) reversed the effects of clonidine. The inhibitory action of noradrenaline was not seen in the neurons pretreated with pertussis toxin (100 μg/ml for 24 h) and the neurons dialyzed intracellularly with guanosine 5'- [β-thio] diphosphate (GDPβS, 200 μM), the catalytic subunit of protein kinase A (250 U/ml) or okadaic acid (1 μM). These results suggest that noradrenaline directly acts on dorsal root ganglion neurons to inhibit the activity of TRPV1 depending on the activation of α2-adrenoceptors followed by the inhibition of the adenylate cyclase/cAMP/protein kinase A pathway.

  19. Alterations in Neuronal Activity in Basal Ganglia-Thalamocortical Circuits in the Parkinsonian State

    Directory of Open Access Journals (Sweden)

    Adriana eGalvan

    2015-02-01

    Full Text Available In patients with Parkinson’s disease and in animal models of this disorder, neurons in the basal ganglia and related regions in thalamus and cortex show changes that can be recorded by using electrophysiologic single-cell recording techniques, including altered firing rates and patterns, pathologic oscillatory activity and increased inter-neuronal synchronization. In addition, changes in synaptic potentials or in the joint spiking activities of populations of neurons can be monitored as alterations in local field potentials, electroencephalograms or electrocorticograms. Most of the mentioned electrophysiologic changes are probably related to the degeneration of diencephalic dopaminergic neurons, leading to dopamine loss in the striatum and other basal ganglia nuclei, although degeneration of non-dopaminergic cell groups may also have a role. The altered electrical activity of the basal ganglia and associated nuclei may contribute to some of the motor signs of the disease. We here review the current knowledge of the electrophysiologic changes at the single cell level, the level of local populations of neural elements, and the level of the entire basal ganglia-thalamocortical network in parkinsonism, and discuss the possible use of this information to optimize treatment approaches to Parkinson’s disease, such as deep brain stimulation therapy.

  20. Alterations in neuronal activity in basal ganglia-thalamocortical circuits in the parkinsonian state

    Science.gov (United States)

    Galvan, Adriana; Devergnas, Annaelle; Wichmann, Thomas

    2015-01-01

    In patients with Parkinson’s disease and in animal models of this disorder, neurons in the basal ganglia and related regions in thalamus and cortex show changes that can be recorded by using electrophysiologic single-cell recording techniques, including altered firing rates and patterns, pathologic oscillatory activity and increased inter-neuronal synchronization. In addition, changes in synaptic potentials or in the joint spiking activities of populations of neurons can be monitored as alterations in local field potentials (LFPs), electroencephalograms (EEGs) or electrocorticograms (ECoGs). Most of the mentioned electrophysiologic changes are probably related to the degeneration of diencephalic dopaminergic neurons, leading to dopamine loss in the striatum and other basal ganglia nuclei, although degeneration of non-dopaminergic cell groups may also have a role. The altered electrical activity of the basal ganglia and associated nuclei may contribute to some of the motor signs of the disease. We here review the current knowledge of the electrophysiologic changes at the single cell level, the level of local populations of neural elements, and the level of the entire basal ganglia-thalamocortical network in parkinsonism, and discuss the possible use of this information to optimize treatment approaches to Parkinson’s disease, such as deep brain stimulation (DBS) therapy. PMID:25698937

  1. Barreloid Borders and Neuronal Activity Shape Panglial Gap Junction-Coupled Networks in the Mouse Thalamus.

    Science.gov (United States)

    Claus, Lena; Philippot, Camille; Griemsmann, Stephanie; Timmermann, Aline; Jabs, Ronald; Henneberger, Christian; Kettenmann, Helmut; Steinhäuser, Christian

    2018-01-01

    The ventral posterior nucleus of the thalamus plays an important role in somatosensory information processing. It contains elongated cellular domains called barreloids, which are the structural basis for the somatotopic organization of vibrissae representation. So far, the organization of glial networks in these barreloid structures and its modulation by neuronal activity has not been studied. We have developed a method to visualize thalamic barreloid fields in acute slices. Combining electrophysiology, immunohistochemistry, and electroporation in transgenic mice with cell type-specific fluorescence labeling, we provide the first structure-function analyses of barreloidal glial gap junction networks. We observed coupled networks, which comprised both astrocytes and oligodendrocytes. The spread of tracers or a fluorescent glucose derivative through these networks was dependent on neuronal activity and limited by the barreloid borders, which were formed by uncoupled or weakly coupled oligodendrocytes. Neuronal somata were distributed homogeneously across barreloid fields with their processes running in parallel to the barreloid borders. Many astrocytes and oligodendrocytes were not part of the panglial networks. Thus, oligodendrocytes are the cellular elements limiting the communicating panglial network to a single barreloid, which might be important to ensure proper metabolic support to active neurons located within a particular vibrissae signaling pathway. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  2. Neuronal Activity in the Subthalamic Cerebrovasodilator Area under Partial-Gravity Conditions in Rats

    Directory of Open Access Journals (Sweden)

    Zeredo L Zeredo

    2014-03-01

    Full Text Available The reduced-gravity environment in space is known to cause an upward shift in body fluids and thus require cardiovascular adaptations in astronauts. In this study, we recorded in rats the neuronal activity in the subthalamic cerebrovasodilator area (SVA, a key area that controls cerebral blood flow (CBF, in response to partial gravity. “Partial gravity” is the term that defines the reduced-gravity levels between 1 g (the unit gravity acceleration on Earth and 0 g (complete weightlessness in space. Neuronal activity was recorded telemetrically through chronically implanted microelectrodes in freely moving rats. Graded levels of partial gravity from 0.4 g to 0.01 g were generated by customized parabolic-flight maneuvers. Electrophysiological signals in each partial-gravity phase were compared to those of the preceding 1 g level-flight. As a result, SVA neuronal activity was significantly inhibited by the partial-gravity levels of 0.15 g and lower, but not by 0.2 g and higher. Gravity levels between 0.2–0.15 g could represent a critical threshold for the inhibition of neurons in the rat SVA. The lunar gravity (0.16 g might thus trigger neurogenic mechanisms of CBF control. This is the first study to examine brain electrophysiology with partial gravity as an experimental parameter.

  3. Pituitary adenylate cyclase activating polypeptide reduces A-type K+ currents and caspase activity in cultured adult mouse olfactory neurons.

    Science.gov (United States)

    Han, P; Lucero, M T

    2005-01-01

    Pituitary adenylate cyclase activating polypeptide has been shown to reduce apoptosis in neonatal cerebellar and olfactory receptor neurons, however the underlying mechanisms have not been elucidated. In addition, the neuroprotective effects of pituitary adenylate cyclase activating polypeptide have not been examined in adult tissues. To study the effects of pituitary adenylate cyclase activating polypeptide on neurons in apoptosis, we measured caspase activation in adult olfactory receptor neurons in vitro. Interestingly, we found that the protective effects of pituitary adenylate cyclase activating polypeptide were related to the absence of a 4-aminopyridine (IC50=144 microM) sensitive rapidly inactivating potassium current often referred to as A-type current. In the presence of 40 nM pituitary adenylate cyclase activating polypeptide 38, both A-type current and activated caspases were significantly reduced. A-type current reduction by pituitary adenylate cyclase activating polypeptide was blocked by inhibiting the phospholipase C pathway, but not the adenylyl cyclase pathway. Our observation that 5 mM 4-aminopyridine mimicked the caspase inhibiting effects of pituitary adenylate cyclase activating polypeptide indicates that A-type current is involved in apoptosis. This work contributes to our growing understanding that potassium currents are involved with the activation of caspases to affect the balance between cell life and death.

  4. Activity of D1/2 Receptor Expressing Neurons in the Nucleus Accumbens Regulates Running, Locomotion, and Food Intake

    Directory of Open Access Journals (Sweden)

    Xianglong eZhu

    2016-04-01

    Full Text Available While weight gain is clearly promoted by excessive energy intake and reduced expenditure, the underlying neural mechanisms of energy balance remain unclear. The NAc is one brain region that has received attention for its role in the regulation of energy balance; its D1 and D2 receptor containing neurons have distinct functions in regulating reward behavior and require further examination. The goal of the present study is to investigate how activation and inhibition of D1 and D2 neurons in the NAc influences behaviors related to energy intake and expenditure. Specific manipulation of D1 vs D2 neurons was done in both low expenditure and high expenditure (wheel running conditions to assess behavioral effects in these different states. Direct control of neural activity was achieved using a DREADD (Designer Receptors Exclusively Activated by Designer Drugs strategy. Activation of NAc D1 neurons increased food intake, wheel running and locomotor activity. In contrast, activation of D2 neurons in the NAc reduced running and locomotion while D2 neuron inhibition had opposite effects. These results highlight the importance of considering both intake and expenditure in the analysis of D1 and D2 neuronal manipulations. Moreover, the behavioral outcomes from D1 NAc neuronal manipulations depend upon the activity state of the animals (wheel running vs non-running. The data support and complement the hypothesis of specific NAc dopamine pathways facilitating energy expenditure and suggest a potential strategy for human weight control.

  5. Involvement of serotonin 2A receptor activation in modulating medial prefrontal cortex and amygdala neuronal activation during novelty-exposure.

    Science.gov (United States)

    Hervig, Mona El-Sayed; Jensen, Nadja Cecilie Hvid; Rasmussen, Nadja Bredo; Rydbirk, Rasmus; Olesen, Mikkel Vestergaard; Hay-Schmidt, Anders; Pakkenberg, Bente; Aznar, Susana

    2017-05-30

    The medial prefrontal cortex (PFC) plays a major role in executive function by exerting a top-down control onto subcortical areas. Novelty-induced frontal cortex activation is 5-HT 2A receptor (5-HT 2A R) dependent. Here, we further investigated how blockade of 5-HT 2A Rs in mice exposed to a novel open-field arena affects medial PFC activation and basolateral amygdala (BLA) reactivity. We used c-Fos immunoreactivity (IR) as a marker of neuronal activation and stereological quantification for obtaining the total number of c-Fos-IR neurons as a measure of regional activation. We further examined the impact of 5-HT 2A R blockade on the striatal-projecting BLA neurons. Systemic administration of ketanserin (0.5mg/kg) prior to novel open-field exposure resulted in reduced total numbers of c-Fos-IR cells in dorsomedial PFC areas and the BLA. Moreover, there was a positive correlation between the relative time spent in the centre of the open-field and BLA c-Fos-IR in the ketanserin-treated animals. Unilateral medial PFC lesions blocked this effect, ascertaining an involvement of this frontal cortex area. On the other hand, medial PFC lesioning exacerbated the more anxiogenic-like behaviour of the ketanserin-treated animals, upholding its involvement in modulating averseness. Ketanserin did not affect the number of activated striatal-projecting BLA neurons (measured by number of Cholera Toxin b (CTb) retrograde labelled neurons also being c-Fos-IR) following CTb injection in the ventral striatum. These results support a role of 5-HT 2A R activation in modulating mPFC and BLA activation during exposure to a novel environment, which may be interrelated. Conversely, 5-HT 2A R blockade does not seem to affect the amygdala-striatal projection. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Neuron to astrocyte communication via cannabinoid receptors is necessary for sustained epileptiform activity in rat hippocampus.

    Directory of Open Access Journals (Sweden)

    Guyllaume Coiret

    Full Text Available Astrocytes are integral functional components of synapses, regulating transmission and plasticity. They have also been implicated in the pathogenesis of epilepsy, although their precise roles have not been comprehensively characterized. Astrocytes integrate activity from neighboring synapses by responding to neuronally released neurotransmitters such as glutamate and ATP. Strong activation of astrocytes mediated by these neurotransmitters can promote seizure-like activity by initiating a positive feedback loop that induces excessive neuronal discharge. Recent work has demonstrated that astrocytes express cannabinoid 1 (CB1 receptors, which are sensitive to endocannabinoids released by nearby pyramidal cells. In this study, we tested whether this mechanism also contributes to epileptiform activity. In a model of 4-aminopyridine induced epileptic-like activity in hippocampal slice cultures, we show that pharmacological blockade of astrocyte CB1 receptors did not modify the initiation, but significantly reduced the maintenance of epileptiform discharge. When communication in astrocytic networks was disrupted by chelating astrocytic calcium, this CB1 receptor-mediated modulation of epileptiform activity was no longer observed. Thus, endocannabinoid signaling from neurons to astrocytes represents an additional significant factor in the maintenance of epileptiform activity in the hippocampus.

  7. Neuron to astrocyte communication via cannabinoid receptors is necessary for sustained epileptiform activity in rat hippocampus.

    Science.gov (United States)

    Coiret, Guyllaume; Ster, Jeanne; Grewe, Benjamin; Wendling, Fabrice; Helmchen, Fritjof; Gerber, Urs; Benquet, Pascal

    2012-01-01

    Astrocytes are integral functional components of synapses, regulating transmission and plasticity. They have also been implicated in the pathogenesis of epilepsy, although their precise roles have not been comprehensively characterized. Astrocytes integrate activity from neighboring synapses by responding to neuronally released neurotransmitters such as glutamate and ATP. Strong activation of astrocytes mediated by these neurotransmitters can promote seizure-like activity by initiating a positive feedback loop that induces excessive neuronal discharge. Recent work has demonstrated that astrocytes express cannabinoid 1 (CB1) receptors, which are sensitive to endocannabinoids released by nearby pyramidal cells. In this study, we tested whether this mechanism also contributes to epileptiform activity. In a model of 4-aminopyridine induced epileptic-like activity in hippocampal slice cultures, we show that pharmacological blockade of astrocyte CB1 receptors did not modify the initiation, but significantly reduced the maintenance of epileptiform discharge. When communication in astrocytic networks was disrupted by chelating astrocytic calcium, this CB1 receptor-mediated modulation of epileptiform activity was no longer observed. Thus, endocannabinoid signaling from neurons to astrocytes represents an additional significant factor in the maintenance of epileptiform activity in the hippocampus.

  8. [Effect of electromagnetic radiation on discharge activity of neurons in the hippocampus CA1 in rats].

    Science.gov (United States)

    Tong, Jun; Chen, Su; Liu, Xiang-Ming; Hao, Dong-Mei

    2013-09-01

    In order to explore effect of electromagnetic radiation on learning and memory ability of hippocampus neuron in rats, the changes in discharge patterns and overall electrical activity of hippocampus neuron after electromagnetic radiation were observed. Rat neurons discharge was recorded with glass electrode extracellular recording technology and a polygraph respectively. Radiation frequency of electromagnetic wave was 900 MHZ and the power was 10 W/m2. In glass electrode extracellular recording, the rats were separately irradiated for 10, 20, 30, 40, 50 and 60 min, every points repeated 10 times and updated interval of 1h, observing the changes in neuron discharge and spontaneous discharge patterns after electromagnetic radiation. In polygraph recording experiments, irradiation group rats for five days a week, 6 hours per day, repeatedly for 10 weeks, memory electrical changes in control group and irradiation group rats when they were feeding were repeatedly monitored by the implanted electrodes, observing the changes in peak electric digits and the largest amplitude in hippocampal CA1 area, and taking some electromagnetic radiation sampling sequence for correlation analysis. (1) Electromagnetic radiation had an inhibitory role on discharge frequency of the hippocampus CA1 region neurons. After electromagnetic radiation, discharge frequency of the hippocampus CA1 region neurons was reduced, but the changes in scale was not obvious. (2) Electromagnetic radiation might change the spontaneous discharge patterns of hippocampus CA1 region neurons, which made the explosive discharge pattern increased obviously. (3) Peak potential total number within 5 min in irradiation group was significantly reduced, the largest amplitude was less than that of control group. (4) Using mathematical method to make the correlation analysis of the electromagnetic radiation sampling sequence, that of irradiation group was less than that of control group, indicating that there was a tending

  9. Comparative Analysis of Human and Rodent Brain Primary Neuronal Culture Spontaneous Activity Using Micro-Electrode Array Technology.

    Science.gov (United States)

    Napoli, Alessandro; Obeid, Iyad

    2016-03-01

    Electrical activity in embryonic brain tissue has typically been studied using Micro Electrode Array (MEA) technology to make dozens of simultaneous recordings from dissociated neuronal cultures, brain stem cell progenitors, or brain slices from fetal rodents. Although these rodent neuronal primary culture electrical properties are mostly investigated, it has not been yet established to what extent the electrical characteristics of rodent brain neuronal cultures can be generalized to those of humans. A direct comparison of spontaneous spiking activity between rodent and human primary neurons grown under the same in vitro conditions using MEA technology has never been carried out before and will be described in the present study. Human and rodent dissociated fetal brain neuronal cultures were established in-vitro by culturing on a glass grid of 60 planar microelectrodes neurons under identical conditions. Three different cultures of human neurons were produced from tissue sourced from a single aborted fetus (at 16-18 gestational weeks) and these were compared with seven different cultures of embryonic rat neurons (at 18 gestational days) originally isolated from a single rat. The results show that the human and rodent cultures behaved significantly differently. Whereas the rodent cultures demonstrated robust spontaneous activation and network activity after only 10 days, the human cultures required nearly 40 days to achieve a substantially weaker level of electrical function. These results suggest that rat neuron preparations may yield inferences that do not necessarily transfer to humans. © 2015 Wiley Periodicals, Inc.

  10. Activity-based anorexia activates nesfatin-1 immunoreactive neurons in distinct brain nuclei of female rats.

    Science.gov (United States)

    Scharner, Sophie; Prinz, Philip; Goebel-Stengel, Miriam; Lommel, Reinhard; Kobelt, Peter; Hofmann, Tobias; Rose, Matthias; Stengel, Andreas

    2017-12-15

    Activity-based anorexia (ABA) is an established animal model for the eating disorder anorexia nervosa (AN). The pathophysiology of AN and the involvement of food intake-regulatory peptides is still poorly understood. Nesfatin-1, an anorexigenic peptide also involved in the mediation of stress, anxiety and depression might be a likely candidate involved in the pathogenesis of AN. Therefore, activation of nesfatin-1 immunoreactive (ir) brain nuclei was investigated under conditions of ABA. Female Sprague-Dawley rats were used and divided into four groups (n=6/group): activity-based anorexia (ABA), restricted feeding (RF), activity (AC) and ad libitum fed (AL). After the 21-day experimental period and development of ABA, brains were processed for c-Fos/nesfatin-1 double labeling immunohistochemistry. ABA increased the number of nesfatin-1 immunopositive neurons in the paraventricular nucleus, arcuate nucleus, dorsomedial hypothalamic nucleus, locus coeruleus and in the rostral part of the nucleus of the solitary tract compared to AL and AC groups (p0.05). Moreover, we observed significantly more c-Fos and nesfatin-1 ir double-labeled cells in ABA rats compared to RF, AL and AC in the supraoptic nucleus (p<0.05) and compared to AL and AC in the paraventricular nucleus, arcuate nucleus, dorsomedial hypothalamic nucleus, dorsal raphe nucleus and the rostral raphe pallidus (p<0.05). Since nesfatin-1 plays a role in the inhibition of food intake and the response to stress, we hypothesize that the observed changes of brain nesfatin-1 might play a role in the pathophysiology and symptomatology under conditions of ABA and potentially also in patients with AN. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Prepubertal Development of Gonadotropin-Releasing Hormone Neuron Activity Is Altered by Sex, Age, and Prenatal Androgen Exposure.

    Science.gov (United States)

    Dulka, Eden A; Moenter, Suzanne M

    2017-11-01

    Gonadotropin-releasing hormone (GnRH) neurons regulate reproduction though pulsatile hormone release. Disruption of GnRH release as measured via luteinizing hormone (LH) pulses occurs in polycystic ovary syndrome (PCOS), and in young hyperandrogenemic girls. In adult prenatally androgenized (PNA) mice, which exhibit many aspects of PCOS, increased LH is associated with increased GnRH neuron action potential firing. How GnRH neuron activity develops over the prepubertal period and whether this is altered by sex or prenatal androgen treatment are unknown. We hypothesized GnRH neurons are active before puberty and that this activity is sexually differentiated and altered by PNA. Dams were injected with dihydrotestosterone (DHT) on days 16 to 18 post copulation to generate PNA mice. Action potential firing of GFP-identified GnRH neurons in brain slices from 1-, 2-, 3-, and 4-week-old and adult mice was monitored. GnRH neurons were active at all ages tested. In control females, activity increased with age through 3 weeks, then decreased to adult levels. In contrast, activity did not change in PNA females and was reduced at 3 weeks. Activity was higher in control females than males from 2 to 3 weeks. PNA did not affect GnRH neuron firing rate in males at any age. Short-term action potential patterns were also affected by age and PNA treatment. GnRH neurons are thus typically more active during the prepubertal period than adulthood, and PNA reduces prepubertal activity in females. Prepubertal activity may play a role in establishing sexually differentiated neuronal networks upstream of GnRH neurons; androgen-induced changes during this time may contribute to the adult PNA, and possibly PCOS, phenotype. Copyright © 2017 Endocrine Society.

  12. Nanomolar Bifenthrin Alters Synchronous Ca2+ Oscillations and Cortical Neuron Development Independent of Sodium Channel Activity

    OpenAIRE

    Cao, Zhengyu; Cui, Yanjun; Nguyen, Hai M.; Jenkins, David Paul; Wulff, Heike; Pessah, Isaac N.

    2014-01-01

    Bifenthrin, a relatively stable type I pyrethroid that causes tremors and impairs motor activity in rodents, is broadly used. We investigated whether nanomolar bifenthrin alters synchronous Ca 2+ oscillations (SCOs) necessary for activity-dependent dendritic development. Primary mouse cortical neurons were cultured 8 or 9 days in vitro (DIV), loaded with the Ca2+ indicator Fluo-4, and imaged using a Fluorescence Imaging Plate Reader Tetra. Acute exposure to bifenthrin rapidly increased the fr...

  13. Differential activation of an identified motor neuron and neuromodulation provide Aplysia's retractor muscle an additional function.

    Science.gov (United States)

    McManus, Jeffrey M; Lu, Hui; Cullins, Miranda J; Chiel, Hillel J

    2014-08-15

    To survive, animals must use the same peripheral structures to perform a variety of tasks. How does a nervous system employ one muscle to perform multiple functions? We addressed this question through work on the I3 jaw muscle of the marine mollusk Aplysia californica's feeding system. This muscle mediates retraction of Aplysia's food grasper in multiple feeding responses and is innervated by a pool of identified neurons that activate different muscle regions. One I3 motor neuron, B38, is active in the protraction phase, rather than the retraction phase, suggesting the muscle has an additional function. We used intracellular, extracellular, and muscle force recordings in several in vitro preparations as well as recordings of nerve and muscle activity from intact, behaving animals to characterize B38's activation of the muscle and its activity in different behavior types. We show that B38 specifically activates the anterior region of I3 and is specifically recruited during one behavior, swallowing. The function of this protraction-phase jaw muscle contraction is to hold food; thus the I3 muscle has an additional function beyond mediating retraction. We additionally show that B38's typical activity during in vivo swallowing is insufficient to generate force in an unmodulated muscle and that intrinsic and extrinsic modulation shift the force-frequency relationship to allow contraction. Using methods that traverse levels from individual neuron to muscle to intact animal, we show how regional muscle activation, differential motor neuron recruitment, and neuromodulation are key components in Aplysia's generation of multifunctionality. Copyright © 2014 the American Physiological Society.

  14. Modafinil enhances thalamocortical activity by increasing neuronal electrotonic coupling

    Science.gov (United States)

    Urbano, Francisco J.; Leznik, Elena; Llinás, Rodolfo R.

    2007-01-01

    Modafinil (Provigil, Modiodal), an antinarcoleptic and mood-enhancing drug, is shown here to sharpen thalamocortical activity and to increase electrical coupling between cortical interneurons and between nerve cells in the inferior olivary nucleus. After irreversible pharmacological block of connexin permeability (i.e., by using either 18β-glycyrrhetinic derivatives or mefloquine), modafinil restored electrotonic coupling within 30 min. It was further established that this restoration is implemented through a Ca2+/calmodulin protein kinase II-dependent step. PMID:17640897

  15. Visualization of odor-induced neuronal activity by immediate early gene expression

    Directory of Open Access Journals (Sweden)

    Bepari Asim K

    2012-11-01

    Full Text Available Abstract Background Sensitive detection of sensory-evoked neuronal activation is a key to mechanistic understanding of brain functions. Since immediate early genes (IEGs are readily induced in the brain by environmental changes, tracing IEG expression provides a convenient tool to identify brain activity. In this study we used in situ hybridization to detect odor-evoked induction of ten IEGs in the mouse olfactory system. We then analyzed IEG induction in the cyclic nucleotide-gated channel subunit A2 (Cnga2-null mice to visualize residual neuronal activity following odorant exposure since CNGA2 is a key component of the olfactory signal transduction pathway in the main olfactory system. Results We observed rapid induction of as many as ten IEGs in the mouse olfactory bulb (OB after olfactory stimulation by a non-biological odorant amyl acetate. A robust increase in expression of several IEGs like c-fos and Egr1 was evident in the glomerular layer, the mitral/tufted cell layer and the granule cell layer. Additionally, the neuronal IEG Npas4 showed steep induction from a very low basal expression level predominantly in the granule cell layer. In Cnga2-null mice, which are usually anosmic and sexually unresponsive, glomerular activation was insignificant in response to either ambient odorants or female stimuli. However, a subtle induction of c-fos took place in the OB of a few Cnga2-mutants which exhibited sexual arousal. Interestingly, very strong glomerular activation was observed in the OB of Cnga2-null male mice after stimulation with either the neutral odor amyl acetate or the predator odor 2, 3, 5-trimethyl-3-thiazoline (TMT. Conclusions This study shows for the first time that in vivo olfactory stimulation can robustly induce the neuronal IEG Npas4 in the mouse OB and confirms the odor-evoked induction of a number of IEGs. As shown in previous studies, our results indicate that a CNGA2-independent signaling pathway(s may activate the

  16. Long-Term Plasticity of Astrocytic Metabotropic Neurotransmitter Receptors Driven by Changes in Neuronal Activity in Hippocampal Slices

    OpenAIRE

    Xie, Xiaoqiao

    2011-01-01

    In addition to synaptic communication between neurons, there is now strong evidence for neuron-to-astrocyte receptor signaling in the brain. During trains of action potentials or repetitive stimulation, neurotransmitter spills out of the synapse to activate astrocytic Gq protein-coupled receptors (Gq GPCRs). To date, very little is known about the ability of astrocytic receptors to exhibit plasticity as a result of long-term changes in neuronal firing rates. Here we describe for the first tim...

  17. [ERK activation effects on GABA secretion inhibition induced by SDF-1 in hippocampal neurons of rats].

    Science.gov (United States)

    Zhang, Zi-juan; Guo, Mei-xia; Xing, Ying

    2015-09-01

    To investigate the effect of extracellular regulating kinase (ERK) signaling pathway on the secretion of gamma-aminobutyric acid (GABA) in cultured rat hippocampal neurons induced by stromal cell derived factor-1 (SDF-1). The hippocampal neurons of newborn SD rats were cultured and identified in vitro; the phosphorylation level of ERK1/2 was examined by Western blot; ELISA was used to detect the effect of PD98059, a ERK1/2 specific blocker on GABA secretion of cultured hippocampal neurons and Western blot were adopted to measure the protein expression levels of glutamate decarboxylase (GAD65/67) and gamma aminobutyric acid transporter (GAT); after blocking ERK1/2 signaling pathway with PD98059; RT-PCR was used to detect the mRNA expression levels of GAT-1 and GAD65 after treated with PD98059. The levels of ERKl/2 phosphorylation were increased significantly by SDF1 acting on hippocampal neurons, and CX-CR4 receptor blocker AMD3100, could inhibit SDF-1 induced ERK1/2 activation; SDF-1 could inhibit the secretion of GABA in cultured hippocampal neurons, and ERK1/2 specific inhibitor PD98059, could partly reverse the inhibition of GABA secretion by SDF-1. The effects of SDF-1 on cultured hippocampal neurons was to decrease the mRNA genesis of glutamic acid decarboxylase GAD65 and GABA transporter GAT-1, besides, ERK inhibitor PD98059 could effectively flip the effect of SDF-1. The results of Western blot showed that SDF-1 could inhibit the protein expression of GAT-1 and GAD65/67 in hippocampal neurons and the inhibition of GAT-1 and GAD65/67 protein expression could be partially restored by ERK1/2 blocker. SDF-1 acts on the CXCR4 of hippocampal neurons in vitro, and inhibits the expression of GAD by activating the ERK1/2 signaling pathway, and this may represent one possible pathway of GABA secretion inhibition.

  18. Cloning, Expression and Purification of the Recombinant HIV-1 Tat-Nef Fusion Protein in Prokaryotic Expression System

    OpenAIRE

    Somayeh Kadkhodayan; Shiva Irani; Seyed Mehdi Sadat; Fatemeh Fotouhi; Azam Bolhassani

    2016-01-01

    Abstract Background: Nef is one of the HIV-1 critical proteins, because it is essential for viral replication and AIDS disease progression and induction of immune response against it can partially inhibit viral infection. Moreover, a domain of the HIV-1 Trans-Activator of Transcription (Tat, 48-60 aa) could act as a cell penetrating peptide (CPP). In current study, cloning and expression of Tat-Nef fusion protein was performed in E. coli for the first time. The protein expression was confi...

  19. Control of phase synchronization of neuronal activity in the rat hippocampus.

    Science.gov (United States)

    Lian, Jun; Shuai, Jianwei; Durand, Dominique M

    2004-03-01

    Analysis of the synchronization mechanisms of neural activity is crucial to the understanding of the generation, propagation and control of epileptiform activity. Recently, phase synchronization (PS) analysis was applied to quantify the partial synchrony that exists in complex chaotic or noisy systems. In a previous study, we have shown that neural activity between two remotely located sites can be synchronized through a complete cut of the tissue by endogenous non-synaptic signals. Therefore, it should be possible to apply signals to control PS. In this study, we test the hypothesis that stimulation amplitudes below excitation level (sub-threshold) can be used to control phase synchronization of two neural signals and we investigate the underlying mechanisms. PS of neuronal activity is first analysed in two coupled Rossler neuron models. Both synchronization and desynchronization could be generated with sub-threshold sinusoidal stimulation. Phase synchronization was then studied in in vitro brain slices. Neuronal activity between two sites was modulated by the application of small sinusoidal electric fields. PS between two remote sites could be achieved by the application of two identical waveforms while phase desynchronization of two close sites was generated by the application of a stimulus at a single site. These results show that sub-threshold stimuli are able to phase synchronize or desynchronize two networks and suggest that small signals could play an important role in normal neural activity and epilepsy.

  20. Computational Study of Subdural Cortical Stimulation: Effects of Simulating Anisotropic Conductivity on Activation of Cortical Neurons.

    Directory of Open Access Journals (Sweden)

    Hyeon Seo

    Full Text Available Subdural cortical stimulation (SuCS is an appealing method in the treatment of neurological disorders, and computational modeling studies of SuCS have been applied to determine the optimal design for electrotherapy. To achieve a better understanding of computational modeling on the stimulation effects of SuCS, the influence of anisotropic white matter conductivity on the activation of cortical neurons was investigated in a realistic head model. In this paper, we constructed pyramidal neuronal models (layers 3 and 5 that showed primary excitation of the corticospinal tract, and an anatomically realistic head model reflecting complex brain geometry. The anisotropic information was acquired from diffusion tensor magnetic resonance imaging (DT-MRI and then applied to the white matter at various ratios of anisotropic conductivity. First, we compared the isotropic and anisotropic models; compared to the isotropic model, the anisotropic model showed that neurons were activated in the deeper bank during cathodal stimulation and in the wider crown during anodal stimulation. Second, several popular anisotropic principles were adapted to investigate the effects of variations in anisotropic information. We observed that excitation thresholds varied with anisotropic principles, especially with anodal stimulation. Overall, incorporating anisotropic conductivity into the anatomically realistic head model is critical for accurate estimation of neuronal responses; however, caution should be used in the selection of anisotropic information.

  1. A reanalysis of "Two types of asynchronous activity in networks of excitatory and inhibitory spiking neurons".

    Science.gov (United States)

    Engelken, Rainer; Farkhooi, Farzad; Hansel, David; van Vreeswijk, Carl; Wolf, Fred

    2016-01-01

    Neuronal activity in the central nervous system varies strongly in time and across neuronal populations. It is a longstanding proposal that such fluctuations generically arise from chaotic network dynamics. Various theoretical studies predict that the rich dynamics of rate models operating in the chaotic regime can subserve circuit computation and learning. Neurons in the brain, however, communicate via spikes and it is a theoretical challenge to obtain similar rate fluctuations in networks of spiking neuron models. A recent study investigated spiking balanced networks of leaky integrate and fire (LIF) neurons and compared their dynamics to a matched rate network with identical topology, where single unit input-output functions were chosen from isolated LIF neurons receiving Gaussian white noise input. A mathematical analogy between the chaotic instability in networks of rate units and the spiking network dynamics was proposed. Here we revisit the behavior of the spiking LIF networks and these matched rate networks. We find expected hallmarks of a chaotic instability in the rate network: For supercritical coupling strength near the transition point, the autocorrelation time diverges. For subcritical coupling strengths, we observe critical slowing down in response to small external perturbations. In the spiking network, we found in contrast that the timescale of the autocorrelations is insensitive to the coupling strength and that rate deviations resulting from small input perturbations rapidly decay. The decay speed even accelerates for increasing coupling strength. In conclusion, our reanalysis demonstrates fundamental differences between the behavior of pulse-coupled spiking LIF networks and rate networks with matched topology and input-output function. In particular there is no indication of a corresponding chaotic instability in the spiking network.

  2. TAT-Gap19 and Carbenoxolone Alleviate Liver Fibrosis in Mice

    Directory of Open Access Journals (Sweden)

    Sara Crespo Yanguas

    2018-03-01

    Full Text Available Although a plethora of signaling pathways are known to drive the activation of hepatic stellate cells in liver fibrosis, the involvement of connexin-based communication in this process remains elusive. Connexin43 expression is enhanced in activated hepatic stellate cells and constitutes the molecular building stone of hemichannels and gap junctions. While gap junctions support intercellular communication, and hence the maintenance of liver homeostasis, hemichannels provide a circuit for extracellular communication and are typically opened by pathological stimuli, such as oxidative stress and inflammation. The present study was set up to investigate the effects of inhibition of connexin43-based hemichannels and gap junctions on liver fibrosis in mice. Liver fibrosis was induced by administration of thioacetamide to Balb/c mice for eight weeks. Thereafter, mice were treated for two weeks with TAT-Gap19, a specific connexin43 hemichannel inhibitor, or carbenoxolone, a general hemichannel and gap junction inhibitor. Subsequently, histopathological analysis was performed and markers of hepatic damage and functionality, oxidative stress, hepatic stellate cell activation and inflammation were evaluated. Connexin43 hemichannel specificity of TAT-Gap19 was confirmed in vitro by fluorescence recovery after photobleaching analysis and the measurement of extracellular release of adenosine-5′-triphosphate. Upon administration to animals, both TAT-Gap19 and carbenoxolone lowered the degree of liver fibrosis accompanied by superoxide dismutase overactivation and reduced production of inflammatory proteins, respectively. These results support a role of connexin-based signaling in the resolution of liver fibrosis, and simultaneously demonstrate the therapeutic potential of TAT-Gap19 and carbenoxolone in the treatment of this type of chronic liver disease.

  3. Cre Activated and Inactivated Recombinant Adeno-Associated Viral Vectors for Neuronal Anatomical Tracing or Activity Manipulation.

    Science.gov (United States)

    Saunders, Arpiar; Sabatini, Bernardo L

    2015-07-01

    Recombinant adeno-associated viruses (rAAVs) transcriptionally activated by Cre recombinase (Cre-On) are powerful tools for determining the anatomy and function of genetically defined neuronal types in transgenic Cre driver mice. Here we describe how rAAVs transcriptionally inactivated by Cre (Cre-Off) can be used in conjunction with Cre-On rAAVs or genomic Cre-reporter alleles to study brain circuits. Intracranial injection of Cre-On/Cre-Off rAAVs into spatially intermingled Cre(+) and Cre(-) neurons allows these populations to be differentially labeled or manipulated within individual animals. This comparison helps define the unique properties of Cre(+) neurons, highlighting the specialized role they play in their constituent brain circuits. This protocol touches on the conceptual and experimental background of Cre-Off rAAV systems, including caveats and methods of validation. Copyright © 2015 John Wiley & Sons, Inc.

  4. Physiological basis and image processing in functional magnetic resonance imaging: Neuronal and motor activity in brain

    Directory of Open Access Journals (Sweden)

    Sharma Rakesh

    2004-05-01

    Full Text Available Abstract Functional magnetic resonance imaging (fMRI is recently developing as imaging modality used for mapping hemodynamics of neuronal and motor event related tissue blood oxygen level dependence (BOLD in terms of brain activation. Image processing is performed by segmentation and registration methods. Segmentation algorithms provide brain surface-based analysis, automated anatomical labeling of cortical fields in magnetic resonance data sets based on oxygen metabolic state. Registration algorithms provide geometric features using two or more imaging modalities to assure clinically useful neuronal and motor information of brain activation. This review article summarizes the physiological basis of fMRI signal, its origin, contrast enhancement, physical factors, anatomical labeling by segmentation, registration approaches with examples of visual and motor activity in brain. Latest developments are reviewed for clinical applications of fMRI along with other different neurophysiological and imaging modalities.

  5. Direct evidence for activity-dependent glucose phosphorylation in neurons with implications for the astrocyte-to-neuron lactate shuttle

    OpenAIRE

    Patel, Anant B.; Lai, James C. K.; Chowdhury, Golam M. I.; Hyder, Fahmeed; Rothman, Douglas L.; Shulman, Robert G.; Behar, Kevin L.

    2014-01-01

    A near one-to-one relationship had previously been observed between increments in the fluxes of the glutamate−glutamine neurotransmitter cycle and neuronal glucose oxidation in the tricarboxylic acid (TCA) cycle. This flux relationship was consistent with a hypothesized mechanism involving glycolytic ATP in astrocytes and astrocyte-to-neuron lactate shuttling. Here, 2-fluoro-2-deoxy-d-glucose was used to evaluate the glucose flux through glycolysis and the TCA cycle in nerve terminals isolate...

  6. Overexpression of cypin alters dendrite morphology, single neuron activity, and network properties via distinct mechanisms

    Science.gov (United States)

    Rodríguez, Ana R.; O'Neill, Kate M.; Swiatkowski, Przemyslaw; Patel, Mihir V.; Firestein, Bonnie L.

    2018-02-01

    Objective. This study investigates the effect that overexpression of cytosolic PSD-95 interactor (cypin), a regulator of synaptic PSD-95 protein localization and a core regulator of dendrite branching, exerts on the electrical activity of rat hippocampal neurons and networks. Approach. We cultured rat hippocampal neurons and used lipid-mediated transfection and lentiviral gene transfer to achieve high levels of cypin or cypin mutant (cypinΔPDZ PSD-95 non-binding) expression cellularly and network-wide, respectively. Main results. Our analysis revealed that although overexpression of cypin and cypinΔPDZ increase dendrite numbers and decrease spine density, cypin and cypinΔPDZ distinctly regulate neuronal activity. At the single cell level, cypin promotes decreases in bursting activity while cypinΔPDZ reduces sEPSC frequency and further decreases bursting compared to cypin. At the network level, by using the Fano factor as a measure of spike count variability, cypin overexpression results in an increase in variability of spike count, and this effect is abolished when cypin cannot bind PSD-95. This variability is also dependent on baseline activity levels and on mean spike rate over time. Finally, our spike sorting data show that overexpression of cypin results in a more complex distribution of spike waveforms and that binding to PSD-95 is essential for this complexity. Significance. Our data suggest that dendrite morphology does not play a major role in cypin action on electrical activity.

  7. P21-activated kinase 2 (PAK2) regulates glucose uptake and insulin sensitivity in neuronal cells.

    Science.gov (United States)

    Varshney, Pallavi; Dey, Chinmoy Sankar

    2016-07-05

    P21-activated kinases (PAKs) are recently reported as important players of insulin signaling and glucose homeostasis in tissues like muscle, pancreas and liver. However, their role in neuronal insulin signaling is still unknown. Present study reports the involvement of PAK2 in neuronal insulin signaling, glucose uptake and insulin resistance. Irrespective of insulin sensitivity, insulin stimulation decreased PAK2 activity. PAK2 downregulation displayed marked enhancement of GLUT4 translocation with increase in glucose uptake whereas PAK2 over-expression showed its reduction. Treatment with Akti-1/2 and wortmannin suggested that Akt and PI3K are mediators of insulin effect on PAK2 and glucose uptake. Rac1 inhibition demonstrated decreased PAK2 activity while inhibition of PP2A resulted in increased PAK2 activity, with corresponding changes in glucose uptake. Taken together, present study demonstrates an inhibitory role of insulin signaling (via PI3K-Akt) and PP2A on PAK2 activity and establishes PAK2 as a Rac1-dependent negative regulator of neuronal glucose uptake and insulin sensitivity. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  8. Modulation of the spike activity of neocortex neurons during a conditioned reflex.

    Science.gov (United States)

    Storozhuk, V M; Sanzharovskii, A V; Sachenko, V V; Busel, B I

    2000-01-01

    Experiments were conducted on cats to study the effects of iontophoretic application of glutamate and a number of modulators on the spike activity of neurons in the sensorimotor cortex during a conditioned reflex. These studies showed that glutamate, as well as exerting a direct influence on neuron spike activity, also had a delayed facilitatory action lasting 10-20 min after iontophoresis was finished. Adrenomimetics were found to have a double modulatory effect on intracortical glutamate connections: inhibitory and facilitatory effects were mediated by beta1 and beta2 adrenoceptors respectively. Although dopamine, like glutamate, facilitated neuron spike activity during the period of application, the simultaneous facilitatory actions of glutamate and L-DOPA were accompanied by occlusion of spike activity, and simultaneous application of glutamate and haloperidol suppressed spike activity associated with the conditioned reflex response. Facilitation thus appears to show a significant level of dependence on metabotropic glutamate receptors which, like dopamine receptors, are linked to the intracellular medium via Gi proteins.

  9. Reactive oxygen species mediate TNFR1 increase after TRPV1 activation in mouse DRG neurons

    Directory of Open Access Journals (Sweden)

    Westlund Karin N

    2009-06-01

    Full Text Available Abstract Background Transient receptor potential vanilloid subtype 1 (TRPV1 is activated by low pH/protons and is well known to be involved in hyperalgesia during inflammation. Tumor necrosis factor α (TNF-α, a proinflammatory cytokine, is involved in nociceptive responses causing hyperalgesia through TNF receptor type 1 (TNFR1 activation. Reactive oxygen species (ROS production is also prominently increased in inflamed tissue. The present study investigated TNFR1 receptors in primary cultured mouse dorsal root ganglion (DRG neurons after TRPV1 activation and the involvement of ROS. C57BL/6 mice, both TRPV1 knockout and wild type, were used for immunofluorescent and live cell imaging. The L4 and L5 DRGs were dissected bilaterally and cultured overnight. TRPV1 was stimulated with capsaicin or its potent analog, resiniferatoxin. ROS production was measured with live cell imaging and TNFR1 was detected with immunofluorescence in DRG primary cultures. The TRPV1 knockout mice, TRPV1 antagonist, capsazepine, and ROS scavenger, N-tert-Butyl-α-phenylnitrone (PBN, were employed to explore the functional relationship among TRPV1, ROS and TNFR1 in these studies. Results The results demonstrate that TRPV1 activation increases TNFR1 receptors and ROS generation in primary cultures of mouse DRG neurons. Activated increases in TNFR1 receptors and ROS production are absent in TRPV1 deficient mice. The PBN blocks increases in TNFR1 and ROS production induced by capsaicin/resiniferatoxin. Conclusion TRPV1 activation increases TNFR1 in cultured mouse DRG neurons through a ROS signaling pathway, a novel sensitization mechanism in DRG neurons.

  10. Intracortical Microstimulation (ICMS) Activates Motor Cortex Layer 5 Pyramidal Neurons Mainly Transsynaptically.

    Science.gov (United States)

    Hussin, Ahmed T; Boychuk, Jeffery A; Brown, Andrew R; Pittman, Quentin J; Teskey, G Campbell

    2015-01-01

    Intracortical microstimulation (ICMS) is a technique used for a number of purposes including the derivation of cortical movement representations (motor maps). Its application can activate the output layer 5 of motor cortex and can result in the elicitation of body movements depending upon the stimulus parameters used. The extent to which pyramidal tract projection neurons of the motor cortex are activated transsynaptically or directly by ICMS remains an open question. Given this uncertainty in the mode of activation, we used a preparation that combined patch clamp whole-cell recordings from single layer 5 pyramidal neurons and extracellular ICMS in slices of motor cortex as well as a standard in vivo mapping technique to ask how ICMS activated motor cortex pyramidal neurons. We measured changes in synaptic spike threshold and spiking rate to ICMS in vitro and movement threshold in vivo in the presence or absence of specific pharmacological blockers of glutamatergic (AMPA, NMDA and Kainate) receptors and GABAA receptors. With major excitatory and inhibitory synaptic transmission blocked (with DNQX, APV and bicuculline methiodide), we observed a significant increase in the ICMS current intensity required to elicit a movement in vivo as well as to the first spike and an 85% reduction in spiking responses in vitro. Subsets of neurons were still responsive after the synaptic block, especially at higher current intensities, suggesting a modest direct activation. Taken together our data indicate a mainly synaptic mode of activation to ICMS in layer 5 of rat motor cortex. Copyright © 2015 Elsevier Inc. All rights reserved.

  11. Mirror neuron activation of musicians and non-musicians in response to motion captured piano performances

    DEFF Research Database (Denmark)

    Hou, Jiancheng; Rajmohan, Ravi; Fang, Dan

    2017-01-01

    Mirror neurons (MNs) activate when performing an action and when an observer witnesses the same action performed by another individual. Functional magnetic resonance imaging (fMRI) and presentation of motion captured piano performances were used to identify differences in MN activation...... pronounced in the “Enjoyment” mode. Our findings suggest that activation of MNs is not only initiated by the imagined action of an observed movement, but such activation is modulated by the level of musical expertise and knowledge of associated motor movements that the observer brings to the viewing...

  12. Optogenetic activation of serotonergic terminals facilitates GABAergic inhibitory input to orexin/hypocretin neurons

    OpenAIRE

    Chowdhury, Srikanta; Yamanaka, Akihiro

    2016-01-01

    Orexin/hypocretin neurons play a crucial role in the regulation of sleep/wakefulness, primarily in the maintenance of wakefulness. These neurons innervate wide areas of the brain and receive diverse synaptic inputs including those from serotonergic (5-HT) neurons in the raphe nucleus. Previously we showed that pharmacological application of 5-HT directly inhibited orexin neurons via 5-HT1A receptors. However, it was still unclear how 5-HT neurons regulated orexin neurons since 5-HT neurons co...

  13. Deficient Rab11 activity underlies glucose hypometabolism in primary neurons of Huntington's disease mice

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xueyi, E-mail: xli12@partners.org [Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129 (United States); Valencia, Antonio; McClory, Hollis; Sapp, Ellen; Kegel, Kimberly B. [Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129 (United States); DiFiglia, Marian, E-mail: difiglia@helix.mgh.harvard.edu [Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129 (United States)

    2012-05-18

    Highlights: Black-Right-Pointing-Pointer Primary Huntington's disease neurons are impaired in taking up glucose. Black-Right-Pointing-Pointer Rab11 modulates glucose uptake in neurons. Black-Right-Pointing-Pointer Increasing Rab11 activity attenuates the glucose uptake defect in disease neurons. Black-Right-Pointing-Pointer We provide a novel mechanism for glucose hypometabolism in Huntington's disease. -- Abstract: Huntington's disease (HD) is a progressive neurodegenerative disorder caused by a CAG repeat expansion in the huntingtin gene. Positron emission tomography studies have revealed a decline in glucose metabolism in the brain of patients with HD by a mechanism that has not been established. We examined glucose utilization in embryonic primary cortical neurons of wild-type (WT) and HD knock-in mice, which have 140 CAG repeats inserted in the endogenous mouse huntingtin gene (HD{sup 140Q/140Q}). Primary HD{sup 140Q/140Q} cortical neurons took up significantly less glucose than did WT neurons. Expression of permanently inactive and permanently active forms of Rab11 correspondingly altered glucose uptake in WT neurons, suggesting that normal activity of Rab11 is needed for neuronal uptake of glucose. It is known that Rab11 activity is diminished in HD{sup 140Q/140Q} neurons. Expression of dominant active Rab11 to enhance the activity of Rab11 normalized glucose uptake in HD{sup 140Q/140Q} neurons. These results suggest that deficient activity of Rab11 is a novel mechanism for glucose hypometabolism in HD.

  14. Connectivity, excitability and activity patterns in neuronal networks

    International Nuclear Information System (INIS)

    Le Feber, Joost; Stoyanova, Irina I; Chiappalone, Michela

    2014-01-01

    Extremely synchronized firing patterns such as those observed in brain diseases like epilepsy may result from excessive network excitability. Although network excitability is closely related to (excitatory) connectivity, a direct measure for network excitability remains unavailable. Several methods currently exist for estimating network connectivity, most of which are related to cross-correlation. An example is the conditional firing probability (CFP) analysis which calculates the pairwise probability (CFP i,j ) that electrode j records an action potential at time t = τ, given that electrode i recorded a spike at t = 0. However, electrode i often records multiple spikes within the analysis interval, and CFP values are biased by the on-going dynamic state of the network. Here we show that in a linear approximation this bias may be removed by deconvoluting CFP i,j with the autocorrelation of i (i.e. CFP i,i ), to obtain the single pulse response (SPR i,j )—the average response at electrode j to a single spike at electrode i. Thus, in a linear system SPRs would be independent of the dynamic network state. Nonlinear components of synaptic transmission, such as facilitation and short term depression, will however still affect SPRs. Therefore SPRs provide a clean measure of network excitability. We used carbachol and ghrelin to moderately activate cultured cortical networks to affect their dynamic state. Both neuromodulators transformed the bursting firing patterns of the isolated networks into more dispersed firing. We show that the influence of the dynamic state on SPRs is much smaller than the effect on CFPs, but not zero. The remaining difference reflects the alteration in network excitability. We conclude that SPRs are less contaminated by the dynamic network state and that mild excitation may decrease network excitability, possibly through short term synaptic depression. (papers)

  15. RhoA/Rho Kinase Mediates Neuronal Death Through Regulating cPLA2 Activation.

    Science.gov (United States)

    Wu, Xiangbing; Walker, Chandler L; Lu, Qingbo; Wu, Wei; Eddelman, Daniel B; Parish, Jonathan M; Xu, Xiao-Ming

    2017-11-01

    Activation of RhoA/Rho kinase leads to growth cone collapse and neurite retraction. Although RhoA/Rho kinase inhibition has been shown to improve axon regeneration, remyelination and functional recovery, its role in neuronal cell death remains unclear. To determine whether RhoA/Rho kinase played a role in neuronal death after injury, we investigated the relationship between RhoA/Rho kinase and cytosolic phospholipase A 2 (cPLA 2 ), a lipase that mediates inflammation and cell death, using an in vitro neuronal death model and an in vivo contusive spinal cord injury model performed at the 10th thoracic (T10) vertebral level. We found that co-administration of TNF-α and glutamate induced spinal neuron death, and activation of RhoA, Rho kinase and cPLA 2 . Inhibition of RhoA, Rho kinase and cPLA 2 significantly reduced TNF-α/glutamate-induced cell death by 33, 52 and 43 %, respectively (p < 0.001). Inhibition of RhoA and Rho kinase also significantly downregulated cPLA 2 activation by 66 and 60 %, respectively (p < 0.01). Furthermore, inhibition of RhoA and Rho kinase reduced the release of arachidonic acid, a downstream substrate of cPLA 2 . The immunofluorescence staining showed that ROCK 1 or ROCK 2 , two isoforms of Rho kinase, was co-localized with cPLA 2 in neuronal cytoplasm. Interestingly, co-immunoprecipitation (Co-IP) assay showed that ROCK 1 or ROCK 2 bonded directly with cPLA 2 and phospho-cPLA 2 . When the Rho kinase inhibitor Y27632 was applied in mice with T10 contusion injury, it significantly decreased cPLA 2 activation and expression and reduced injury-induced apoptosis at and close to the lesion site. Taken together, our results reveal a novel mechanism of RhoA/Rho kinase-mediated neuronal death through regulating cPLA 2 activation.

  16. Dietary grape seed polyphenols repress neuron and glia activation in trigeminal ganglion and trigeminal nucleus caudalis

    Directory of Open Access Journals (Sweden)

    Durham Paul L

    2010-12-01

    Full Text Available Abstract Background Inflammation and pain associated with temporomandibular joint disorder, a chronic disease that affects 15% of the adult population, involves activation of trigeminal ganglion nerves and development of peripheral and central sensitization. Natural products represent an underutilized resource in the pursuit of safe and effective ways to treat chronic inflammatory diseases. The goal of this study was to investigate effects of grape seed extract on neurons and glia in trigeminal ganglia and trigeminal nucleus caudalis in response to persistent temporomandibular joint inflammation. Sprague Dawley rats were pretreated with 200 mg/kg/d MegaNatural-BP grape seed extract for 14 days prior to bilateral injections of complete Freund's adjuvant into the temporomandibular joint capsule. Results In response to grape seed extract, basal expression of mitogen-activated protein kinase phosphatase 1 was elevated in neurons and glia in trigeminal ganglia and trigeminal nucleus caudalis, and expression of the glutamate aspartate transporter was increased in spinal glia. Rats on a normal diet injected with adjuvant exhibited greater basal levels of phosphorylated-p38 in trigeminal ganglia neurons and spinal neurons and microglia. Similarly, immunoreactive levels of OX-42 in microglia and glial fibrillary acidic protein in astrocytes were greatly increased in response to adjuvant. However, adjuvant-stimulated levels of phosphorylated-p38, OX-42, and glial fibrillary acidic protein were significantly repressed in extract treated animals. Furthermore, grape seed extract suppressed basal expression of the neuropeptide calcitonin gene-related peptide in spinal neurons. Conclusions Results from our study provide evidence that grape seed extract may be beneficial as a natural therapeutic option for temporomandibular joint disorders by suppressing development of peripheral and central sensitization.

  17. Plasmalogens rescue neuronal cell death through an activation of AKT and ERK survival signaling.

    Directory of Open Access Journals (Sweden)

    Md Shamim Hossain

    Full Text Available Neuronal cells are susceptible to many stresses, which will cause the apoptosis and neurodegenerative diseases. The precise molecular mechanism behind the neuronal protection against these apoptotic stimuli is necessary for drug discovery. In the present study, we have found that plasmalogens (Pls, which are glycerophospholipids containing vinyl ether linkage at sn-1 position, can protect the neuronal cell death upon serum deprivation. Interestingly, caspse-9, but not caspase-8 and caspase-12, was cleaved upon the serum starvation in Neuro-2A cells. Pls treatments effectively reduced the activation of caspase-9. Furthermore, cellular signaling experiments showed that Pls enhanced phosphorylation of the phosphoinositide 3-kinase (PI3K-dependent serine/threonine-specific protein kinase AKT and extracellular-signal-regulated kinases ERK1/2. PI3K/AKT inhibitor LY294002 and MAPK/ERK kinase (MEK inhibitor U0126 treatments study clearly indicated that Pls-mediated cell survival was dependent on the activation of these kinases. In addition, Pls also inhibited primary mouse hippocampal neuronal cell death induced by nutrient deprivation, which was associated with the inhibition of caspase-9 and caspase-3 cleavages. It was reported that Pls content decreased in the brain of the Alzheimer's patients, which indicated that the reduction of Pls content could endanger neurons. The present findings, taken together, suggest that Pls have an anti-apoptotic action in the brain. Further studies on precise mechanisms of Pls-mediated protection against cell death may lead us to establish a novel therapeutic approach to cure neurodegenerative disorders.

  18. A natural diarylheptanoid promotes neuronal differentiation via activating ERK and PI3K-Akt dependent pathways.

    Science.gov (United States)

    Tang, G; Dong, X; Huang, X; Huang, X-J; Liu, H; Wang, Y; Ye, W-C; Shi, L

    2015-09-10

    Neuronal differentiation is a critical developmental process that determines accurate synaptic connection and circuit wiring. A wide variety of naturally occurring compounds have been shown as promising drug leads for the generation and differentiation of neurons. Here we report that a diarylheptanoid from the plant Alpinia officinarum, 7-(4-hydroxyphenyl)-1-phenyl-4E-hepten-3-one (Cpd 1), exhibited potent activities in neuronal differentiation and neurite outgrowth. Cpd 1 induced differentiation of neuroblastoma Neuro-2a cells into a neuron-like morphology, and accelerated the establishment of axon-dendrite polarization of cultured hippocampal neurons. Moreover, Cpd 1 promoted neurite extension in both Neuro-2a cells and neurons. We showed that the effects of Cpd 1 on neuronal differentiation and neurite growth were specifically dependent on the activation of extracellular signal-regulated kinases (ERKs) and phosphoinositide 3-kinase (PI3K)-Akt signaling pathways. Importantly, intraperitoneal administration of Cpd 1 promoted the differentiation of new-born progenitor cells into mature neurons in the adult hippocampal dentate gyrus. Collectively, this study identifies a naturally occurring diarylheptanoid with beneficial effects on neuronal differentiation and neurite outgrowth in vitro and in vivo. Copyright © 2015 IBRO. Published by Elsevier Ltd. All rights reserved.

  19. Autaptic pacemaker mediated propagation of weak rhythmic activity across small-world neuronal networks

    Science.gov (United States)

    Yilmaz, Ergin; Baysal, Veli; Ozer, Mahmut; Perc, Matjaž

    2016-02-01

    We study the effects of an autapse, which is mathematically described as a self-feedback loop, on the propagation of weak, localized pacemaker activity across a Newman-Watts small-world network consisting of stochastic Hodgkin-Huxley neurons. We consider that only the pacemaker neuron, which is stimulated by a subthreshold periodic signal, has an electrical autapse that is characterized by a coupling strength and a delay time. We focus on the impact of the coupling strength, the network structure, the properties of the weak periodic stimulus, and the properties of the autapse on the transmission of localized pacemaker activity. Obtained results indicate the existence of optimal channel noise intensity for the propagation of the localized rhythm. Under optimal conditions, the autapse can significantly improve the propagation of pacemaker activity, but only for a specific range of the autaptic coupling strength. Moreover, the autaptic delay time has to be equal to the intrinsic oscillation period of the Hodgkin-Huxley neuron or its integer multiples. We analyze the inter-spike interval histogram and show that the autapse enhances or suppresses the propagation of the localized rhythm by increasing or decreasing the phase locking between the spiking of the pacemaker neuron and the weak periodic signal. In particular, when the autaptic delay time is equal to the intrinsic period of oscillations an optimal phase locking takes place, resulting in a dominant time scale of the spiking activity. We also investigate the effects of the network structure and the coupling strength on the propagation of pacemaker activity. We find that there exist an optimal coupling strength and an optimal network structure that together warrant an optimal propagation of the localized rhythm.

  20. Optically-Induced Neuronal Activity Is Sufficient to Promote Functional Motor Axon Regeneration In Vivo.

    Directory of Open Access Journals (Sweden)

    Patricia J Ward

    Full Text Available Peripheral nerve injuries are common, and functional recovery is very poor. Beyond surgical repair of the nerve, there are currently no treatment options for these patients. In experimental models of nerve injury, interventions (such as exercise and electrical stimulation that increase neuronal activity of the injured neurons effectively enhance axon regeneration. Here, we utilized optogenetics to determine whether increased activity alone is sufficient to promote motor axon regeneration. In thy-1-ChR2/YFP transgenic mice in which a subset of motoneurons express the light-sensitive cation channel, channelrhodopsin (ChR2, we activated axons in the sciatic nerve using blue light immediately prior to transection and surgical repair of the sciatic nerve. At four weeks post-injury, direct muscle EMG responses evoked with both optical and electrical stimuli as well as the ratio of these optical/electrical evoked EMG responses were significantly greater in mice that received optical treatment. Thus, significantly more ChR2+ axons successfully re-innervated the gastrocnemius muscle in mice that received optical treatment. Sections of the gastrocnemius muscles were reacted with antibodies to Synaptic Vesicle Protein 2 (SV2 to quantify the number of re-occupied motor endplates. The number of SV2+ endplates was greater in mice that received optical treatment. The number of retrogradely-labeled motoneurons following intramuscular injection of cholera toxin subunit B (conjugated to Alexa Fluor 555 was greater in mice that received optical treatment. Thus, the acute (1 hour, one-time optical treatment resulted in robust, long-lasting effects compared to untreated animals as well as untreated axons (ChR2-. We conclude that neuronal activation is sufficient to promote motor axon regeneration, and this regenerative effect is specific to the activated neurons.

  1. Electrophysiological characterization of harmane-induced activation of mesolimbic dopamine neurons.

    Science.gov (United States)

    Arib, Ouafa; Rat, Pascal; Molimard, Robert; Chait, Abderrahman; Faure, Philippe; de Beaurepaire, Renaud

    2010-03-10

    It has been suggested that the beta-carbolines harmane and norharmane may be involved in the pathophysiology of Parkinson's disease, psychosis and addiction, but the mechanisms of these possible effects remain to be elucidated. In the present study, the effects of the two compounds were examined by using in vivo extracellular recordings of ventral tegmental dopamine neurons. The effects of harmane (2mg/kg) and norharmane (2mg/kg), were compared to those of nicotine (11microg/kg), of cotinine (0.5mg/kg), of the monoamine-oxidase-A inhibitor befloxatone (0.12mg/kg), and of the monoamine-oxidase-B inhibitor selegiline (0.5mg/kg). The effects of harmane were also tested after pre-treatment with the nicotine receptor antagonist mecamylamine. The results show that all substances, except befloxatone, activate the firing and/or burst activity of dopamine neurons. The increase in firing rate produced by harmane was approximately 18 times greater than that produced by nicotine. Such powerful excitation of dopamine neurons by harmane may in part explain its involvement in neurotoxicity, psychosis and addiction. The absence of effect of befloxatone supports the hypothesis that the effect of harmane is not related to its monoamine-oxidase-A inhibitory properties. Mecamylamine inhibited by approximately 80% the activity of harmane, indicating that the activating effect of harmane on dopamine neurons involves several mechanisms, among which activation of nicotinic receptors likely has a prominent importance. The results of the present study support the hypothesis that harmane could be a tobacco (or smoke) component other than nicotine involved in tobacco dependence. Copyright (c) 2009 Elsevier B.V. All rights reserved.

  2. Area PEc Neurons Use a Multiphasic Pattern of Activity to Signal the Spatial Properties of Optic Flow

    Directory of Open Access Journals (Sweden)

    Milena Raffi

    2017-01-01

    Full Text Available The cortical representation of visual perception requires the integration of several-signal processing distributed across many cortical areas, but the neural substrates of such perception are largely unknown. The type of firing pattern exhibited by single neurons is an important indicator of dynamic circuitry within or across cortical areas. Neurons in area PEc are involved in the spatial mapping of the visual field; thus, we sought to analyze the firing pattern of activity of PEc optic flow neurons to shed some light on the cortical processing of visual signals. We quantified the firing activity of 152 optic flow neurons using a spline interpolation function, which allowed determining onset, end, and latency of each neuronal response. We found that many PEc neurons showed multiphasic activity, which is strictly related to the position of the eye and to the position of the focus of expansion (FOE of the flow field. PEc neurons showed a multiphasic activity comprised of excitatory phases interspersed with inhibitory pauses. This phasic pattern seems to be a very efficient way to signal the spatial location of visual stimuli, given that the same neuron sends different firing patterns according to a specific combination of FOE/eye position.

  3. Serotonin 2C receptor activates a distinct population of arcuate pro-opiomelanocortin neurons via TRPC channels

    Science.gov (United States)

    Serotonin 2C receptors (5-HT2CRs) expressed by pro-opiomelanocortin (POMC) neurons of hypothalamic arcuate nucleus regulate food intake, energy homeostasis ,and glucose metabolism. However, the cellular mechanisms underlying the effects of 5-HT to regulate POMC neuronal activity via 5-HT2CRs have no...

  4. Decoupled choice-driven and stimulus-related activity in parietal neurons may be misrepresented by choice probabilities.

    Science.gov (United States)

    Zaidel, Adam; DeAngelis, Gregory C; Angelaki, Dora E

    2017-09-28

    Trial-by-trial correlations between neural responses and choices (choice probabilities) are often interpreted to reflect a causal contribution of neurons to task performance. However, choice probabilities may arise from top-down, rather than bottom-up, signals. We isolated distinct sensory and decision contributions to single-unit activity recorded from the dorsal medial superior temporal (MSTd) and ventral intraparietal (VIP) areas of monkeys during perception of self-motion. Superficially, neurons in both areas show similar tuning curves during task performance. However, tuning in MSTd neurons primarily reflects sensory inputs, whereas choice-related signals dominate tuning in VIP neurons. Importantly, the choice-related activity of VIP neurons is not predictable from their stimulus tuning, and these factors are often confounded in choice probability measurements. This finding was confirmed in a subset of neurons for which stimulus tuning was measured during passive fixation. Our findings reveal decoupled stimulus and choice signals in the VIP area, and challenge our understanding of choice signals in the brain.Choice-related signals in neuronal activity may reflect bottom-up sensory processes, top-down decision-related influences, or a combination of the two. Here the authors report that choice-related activity in VIP neurons is not predictable from their stimulus tuning, and that dominant choice signals can bias the standard metric of choice preference (choice probability).

  5. Abnormal neuronal activity in Tourette syndrome and its modulation using deep brain stimulation

    Science.gov (United States)

    Israelashvili, Michal; Loewenstern, Yocheved

    2015-01-01

    Tourette syndrome (TS) is a common childhood-onset disorder characterized by motor and vocal tics that are typically accompanied by a multitude of comorbid symptoms. Pharmacological treatment options are limited, which has led to the exploration of deep brain stimulation (DBS) as a possible treatment for severe cases. Multiple lines of evidence have linked TS with abnormalities in the motor and limbic cortico-basal ganglia (CBG) pathways. Neurophysiological data have only recently started to slowly accumulate from multiple sources: noninvasive imaging and electrophysiological techniques, invasive electrophysiological recordings in TS patients undergoing DBS implantation surgery, and animal models of the disorder. These converging sources point to system-level physiological changes throughout the CBG pathway, including both general altered baseline neuronal activity patterns and specific tic-related activity. DBS has been applied to different regions along the motor and limbic pathways, primarily to the globus pallidus internus, thalamic nuclei, and nucleus accumbens. In line with the findings that also draw on the more abundant application of DBS to Parkinson's disease, this stimulation is assumed to result in changes in the neuronal firing patterns and the passage of information through the stimulated nuclei. We present an overview of recent experimental findings on abnormal neuronal activity associated with TS and the changes in this activity following DBS. These findings are then discussed in the context of current models of CBG function in the normal state, during TS, and finally in the wider context of DBS in CBG-related disorders. PMID:25925326

  6. Computational modeling of seizure dynamics using coupled neuronal networks: factors shaping epileptiform activity.

    Directory of Open Access Journals (Sweden)

    Sebastien Naze

    2015-05-01

    Full Text Available Epileptic seizure dynamics span multiple scales in space and time. Understanding seizure mechanisms requires identifying the relations between seizure components within and across these scales, together with the analysis of their dynamical repertoire. Mathematical models have been developed to reproduce seizure dynamics across scales ranging from the single neuron to the neural population. In this study, we develop a network model of spiking neurons and systematically investigate the conditions, under which the network displays the emergent dynamic behaviors known from the Epileptor, which is a well-investigated abstract model of epileptic neural activity. This approach allows us to study the biophysical parameters and variables leading to epileptiform discharges at cellular and network levels. Our network model is composed of two neuronal populations, characterized by fast excitatory bursting neurons and regular spiking inhibitory neurons, embedded in a common extracellular environment represented by a slow variable. By systematically analyzing the parameter landscape offered by the simulation framework, we reproduce typical sequences of neural activity observed during status epilepticus. We find that exogenous fluctuations from extracellular environment and electro-tonic couplings play a major role in the progression of the seizure, which supports previous studies and further validates our model. We also investigate the influence of chemical synaptic coupling in the generation of spontaneous seizure-like events. Our results argue towards a temporal shift of typical spike waves with fast discharges as synaptic strengths are varied. We demonstrate that spike waves, including interictal spikes, are generated primarily by inhibitory neurons, whereas fast discharges during the wave part are due to excitatory neurons. Simulated traces are compared with in vivo experimental data from rodents at different stages of the disorder. We draw the conclusion

  7. Endoplasmic reticulum stress in wake-active neurons progresses with aging.

    Science.gov (United States)

    Naidoo, Nirinjini; Zhu, Jingxu; Zhu, Yan; Fenik, Polina; Lian, Jie; Galante, Ray; Veasey, Sigrid

    2011-08-01

    Fragmentation of wakefulness and sleep are expected outcomes of advanced aging. We hypothesize that wake neurons develop endoplasmic reticulum dyshomeostasis with aging, in parallel with impaired wakefulness. In this series of experiments, we sought to more fully characterize age-related changes in wakefulness and then, in relevant wake neuronal populations, explore functionality and endoplasmic reticulum homeostasis. We report that old mice show greater sleep/wake transitions in the active period with markedly shortened wake periods, shortened latencies to sleep, and less wake time in the subjective day in response to a novel social encounter. Consistent with sleep/wake instability and reduced social encounter wakefulness, orexinergic and noradrenergic wake neurons in aged mice show reduced c-fos response to wakefulness and endoplasmic reticulum dyshomeostasis with increased nuclear translocation of CHOP and GADD34. We have identified an age-related unfolded protein response injury to and dysfunction of wake neurons. It is anticipated that these changes contribute to sleep/wake fragmentation and cognitive impairment in aging. © 2011 The Authors. Aging Cell © 2011 Blackwell Publishing Ltd/Anatomical Society of Great Britain and Ireland.

  8. Layer- and Cell Type-Specific Modulation of Excitatory Neuronal Activity in the Neocortex

    Directory of Open Access Journals (Sweden)

    Gabriele Radnikow

    2018-01-01

    Full Text Available From an anatomical point of view the neocortex is subdivided into up to six layers depending on the cortical area. This subdivision has been described already by Meynert and Brodmann in the late 19/early 20. century and is mainly based on cytoarchitectonic features such as the size and location of the pyramidal cell bodies. Hence, cortical lamination is originally an anatomical concept based on the distribution of excitatory neuron. However, it has become apparent in recent years that apart from the layer-specific differences in morphological features, many functional properties of neurons are also dependent on cortical layer or cell type. Such functional differences include changes in neuronal excitability and synaptic activity by neuromodulatory transmitters. Many of these neuromodulators are released from axonal afferents from subcortical brain regions while others are released intrinsically. In this review we aim to describe layer- and cell-type specific differences in the effects of neuromodulator receptors in excitatory neurons in layers 2–6 of different cortical areas. We will focus on the neuromodulator systems using adenosine, acetylcholine, dopamine, and orexin/hypocretin as examples because these neuromodulator systems show important differences in receptor type and distribution, mode of release and functional mechanisms and effects. We try to summarize how layer- and cell type-specific neuromodulation may affect synaptic signaling in cortical microcircuits.

  9. Nanometric agents in the service of neuroscience: Manipulation of neuronal growth and activity using nanoparticles.

    Science.gov (United States)

    Polak, Pazit; Shefi, Orit

    2015-08-01

    Nerve regeneration and recovery could provide great therapeutic benefits for individuals suffering from nerve damage post trauma or degenerative diseases. However, manipulation of nerves presents a huge challenge for neuroscientists and is not yet clinically feasible. In recent years, nanoparticles have emerged as novel effective agents for control of neuronal growth and behavior. Nanoparticles may facilitate the needed nerve manipulation abilities for therapeutic and diagnostic purposes including within the brain. This review aims at presenting the currently available literature regarding the interactions between inorganic nanoparticles and neurons. A wide range of nanoparticles are presented, including gold, iron oxide, cerium oxide, nanotubes and quantum-dots. The nanoparticles enhance neuronal differentiation and survival, direct growth and regulate electrical activity. The studies are summarized in a concise table, arranged by the function and type of nanoparticle. The latest studies present a novel interdisciplinary approach, which could be harnessed for clinical applications in nanomedicine. Nerve regeneration remains the Holy Grail for patients with neuron loss. Nonetheless, this goal has not been realized in clinical setting thus far. In this article, the authors present a comprehensive review on various nanoparticle-based approaches, in both diagnosis and therapy, which should stimulate and generate more research ideas to the advancement in this field. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Glucose is necessary to maintain neurotransmitter homeostasis during synaptic activity in cultured glutamatergic neurons

    DEFF Research Database (Denmark)

    Bak, Lasse K; Schousboe, Arne; Sonnewald, Ursula

    2006-01-01

    Glucose is the primary energy substrate for the adult mammalian brain. However, lactate produced within the brain might be able to serve this purpose in neurons. In the present study, the relative significance of glucose and lactate as substrates to maintain neurotransmitter homeostasis was inves......Glucose is the primary energy substrate for the adult mammalian brain. However, lactate produced within the brain might be able to serve this purpose in neurons. In the present study, the relative significance of glucose and lactate as substrates to maintain neurotransmitter homeostasis...... was investigated. Cultured cerebellar (primarily glutamatergic) neurons were superfused in medium containing [U-13C]glucose (2.5 mmol/L) and lactate (1 or 5 mmol/L) or glucose (2.5 mmol/L) and [U-13C]lactate (1 mmol/L), and exposed to pulses of N-methyl-D-aspartate (300 micromol/L), leading to synaptic activity...... significantly during induced depolarization. In contrast, at both concentrations of extracellular lactate, the metabolism of [U-13C]glucose was increased during neuronal depolarization. The role of glucose and lactate as energy substrates during vesicular release as well as transporter-mediated influx...

  11. La Somalie en mauvais État

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    Alain Gascon

    2008-05-01

    Full Text Available La Somalie a sombré depuis 1988 dans une guerre civile que rien ne semble pouvoir arrêter. Les chefs de guerre se disputent des portions du territoire en autant de repaires pour y organiser leurs trafics criminels. Expulsés de Mogadiscio par les milices des tribunaux islamiques, ils y sont revenus avec le gouvernement provisoire, réinstallé par l’Éthiopie. Toutefois, au Somaliland, au Nord, les autorités séparatistes ont rétabli la paix sur tout leur territoire, reconstruit les infrastructures et organisé des élections que personne n’a contestées, mais l’ONU, sous la pression conjuguée de la Ligue Arabe et de l’Union africaine, refuse de reconnaître l’indépendance de l’ex-colonie britannique. Après vingt ans d’indifférence à ce lointain conflit, l’État somalien est menacé de disparition.Since 1988 Somalia has sunk into an endless civil war. Warlords have been fighting over parts of the national territory in order to expand their criminal traffics. They were expelled from the capital by the Islamic court militias but they have returned to it when the Provisionnal Government of Somalia was restored by Ethiopia in Mogadisico. Under the pressures of the Arab League and of the African Union the United Nations have constantly refused to recognize the independence of Somaliland, a former British colony, despite its separatist government has brought peace on all their territory, rebuilt equipments and held fair elections. Twenty years of indifference to this remote conflict have threatened the Somalian state to death.

  12. Tissue Plasminogen Activator Induction in Purkinje Neurons After Cerebellar Motor Learning

    Science.gov (United States)

    Seeds, Nicholas W.; Williams, Brian L.; Bickford, Paula C.

    1995-12-01

    The cerebellar cortex is implicated in the learning of complex motor skills. This learning may require synaptic remodeling of Purkinje cell inputs. An extracellular serine protease, tissue plasminogen activator (tPA), is involved in remodeling various nonneural tissues and is associated with developing and regenerating neurons. In situ hybridization showed that expression of tPA messenger RNA was increased in the Purkinje neurons of rats within an hour of their being trained for a complex motor task. Antibody to tPA also showed the induction of tPA protein associated with cerebellar Purkinje cells. Thus, the induction of tPA during motor learning may play a role in activity-dependent synaptic plasticity.

  13. Activation of orexin/hypocretin neurons is associated with individual differences in cued fear extinction.

    Science.gov (United States)

    Sharko, Amanda C; Fadel, Jim R; Kaigler, Kris F; Wilson, Marlene A

    2017-09-01

    Identifying the neurobiological mechanisms that underlie differential sensitivity to stress is critical for understanding the development and expression of stress-induced disorders, such as post-traumatic stress disorder (PTSD). Preclinical studies have suggested that rodents display different phenotypes associated with extinction of Pavlovian conditioned fear responses, with some rodent populations being resistant to extinction. An emerging literature also suggests a role for orexins in the consolidation processes associated with fear learning and extinction. To examine the possibility that the orexin system might be involved in individual differences in fear extinction, we used a Pavlovian conditioning paradigm in outbred Long-Evans rats. Rats showed significant variability in the extinction of cue-conditioned freezing and extinction recall, and animals were divided into groups based on their extinction profiles based on a median split of percent freezing behavior during repeated exposure to the conditioned cue. Animals resistant to extinction (high freezers) showed more freezing during repeated cue presentations during the within trial and between trial extinction sessions compared with the group showing significant extinction (low freezers), although there were no differences between these groups in freezing upon return to the conditioned context or during the conditioning session. Following the extinction recall session, activation of orexin neurons was determined using dual label immunohistochemistry for cFos in orexin positive neurons in the hypothalamus. Individual differences in the extinction of cue conditioned fear were associated with differential activation of hypothalamic orexin neurons. Animals showing poor extinction of cue-induced freezing (high freezers) had significantly greater percentage of orexin neurons with Fos in the medial hypothalamus than animals displaying significant extinction and good extinction recall (low freezers). Further, the

  14. Ejaculation Induced by the Activation of Crz Neurons Is Rewarding to Drosophila Males.

    Science.gov (United States)

    Zer-Krispil, Shir; Zak, Hila; Shao, Lisha; Ben-Shaanan, Shir; Tordjman, Lea; Bentzur, Assa; Shmueli, Anat; Shohat-Ophir, Galit

    2018-05-07

    The reward system is a collection of circuits that reinforce behaviors necessary for survival [1, 2]. Given the importance of reproduction for survival, actions that promote successful mating induce pleasurable feeling and are positively reinforced [3, 4]. This principle is conserved in Drosophila, where successful copulation is naturally rewarding to male flies, induces long-term appetitive memories [5], increases brain levels of neuropeptide F (NPF, the fly homolog of neuropeptide Y), and prevents ethanol, known otherwise as rewarding to flies [6, 7], from being rewarding [5]. It is not clear which of the multiple sensory and motor responses performed during mating induces perception of reward. Sexual interactions with female flies that do not reach copulation are not sufficient to reduce ethanol consumption [5], suggesting that only successful mating encounters are rewarding. Here, we uncoupled the initial steps of mating from its final steps and tested the ability of ejaculation to mimic the rewarding value of full copulation. We induced ejaculation by activating neurons that express the neuropeptide corazonin (CRZ) [8] and subsequently measured different aspects of reward. We show that activating Crz-expressing neurons is rewarding to male flies, as they choose to reside in a zone that triggers optogenetic stimulation of Crz neurons and display conditioned preference for an odor paired with the activation. Reminiscent of successful mating, repeated activation of Crz neurons increases npf levels and reduces ethanol consumption. Our results demonstrate that ejaculation stimulated by Crz/Crz-receptor signaling serves as an essential part of the mating reward mechanism in Drosophila. VIDEO ABSTRACT. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

  15. Altered neuronal activity in the primary motor cortex and globus pallidus after dopamine depletion in rats.

    Science.gov (United States)

    Wang, Min; Li, Min; Geng, Xiwen; Song, Zhimin; Albers, H Elliott; Yang, Maoquan; Zhang, Xiao; Xie, Jinlu; Qu, Qingyang; He, Tingting

    2015-01-15

    The involvement of dopamine (DA) neuron loss in the etiology of Parkinson's disease has been well documented. The neural mechanisms underlying the effects of DA loss and the resultant motor dysfunction remain unknown. To gain insights into how loss of DA disrupts the electrical processes in the cortico-subcortical network, the present study explores the effects of DA neuron depletion on electrical activity in the primary motor cortex (M1), on the external and the internal segment of the globus pallidus (GPe and GPi respectively), and on their temporal relationships. Comparison of local field potentials (LFPs) in these brain regions from unilateral hemispheric DA neuron depleted rats and neurologically intact rats revealed that the spectrum power of LFPs in 12-70Hz (for M1, and GPe) and in 25-40Hz (for GPi) was significantly greater in the DA depleted rats than that in the control group. These changes were associated with a shortening of latency in LFP activities between M1 and GPe, from several hundred milliseconds in the intact animals to close to zero in the DA depleted animals. LFP oscillations in M1 were significantly more synchronized with those in GPe in the DA depleted rats compared with those in the control rats. By contrast, the synchronization of oscillation in LFP activities between M1 and GPi did not differ between the DA depleted and intact rats. Not surprisingly, rats that had DA neuron depletion spent more time along the ladder compared with the control rats. These data suggest that enhanced oscillatory activity and increased synchronization of LFPs may contribute to movement impairment in the rat model of Parkinson's disease. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Angiotensin Type-2 Receptors Influence the Activity of Vasopressin Neurons in the Paraventricular Nucleus of the Hypothalamus in Male Mice.

    Science.gov (United States)

    de Kloet, Annette D; Pitra, Soledad; Wang, Lei; Hiller, Helmut; Pioquinto, David J; Smith, Justin A; Sumners, Colin; Stern, Javier E; Krause, Eric G

    2016-08-01

    It is known that angiotensin-II acts at its type-1 receptor to stimulate vasopressin (AVP) secretion, which may contribute to angiotensin-II-induced hypertension. Less well known is the impact of angiotensin type-2 receptor (AT2R) activation on these processes. Studies conducted in a transgenic AT2R enhanced green fluorescent protein reporter mouse revealed that although AT2R are not themselves localized to AVP neurons within the paraventricular nucleus of the hypothalamus (PVN), they are localized to neurons that extend processes into the PVN. In the present set of studies, we set out to characterize the origin, phenotype, and function of nerve terminals within the PVN that arise from AT2R-enhanced green fluorescent protein-positive neurons and synapse onto AVP neurons. Initial experiments combined genetic and neuroanatomical techniques to determine that γ-aminobutyric acid (GABA)ergic neurons derived from the peri-PVN area containing AT2R make appositions onto AVP neurons within the PVN, thereby positioning AT2R to negatively regulate neuroendocrine secretion. Subsequent patch-clamp electrophysiological experiments revealed that selective activation of AT2R in the peri-PVN area using compound 21 facilitates inhibitory (ie, GABAergic) neurotransmission and leads to reduced activity of AVP neurons within the PVN. Final experiments determined the functional impact of AT2R activation by testing the effects of compound 21 on plasma AVP levels. Collectively, these experiments revealed that AT2R expressing neurons make GABAergic synapses onto AVP neurons that inhibit AVP neuronal activity and suppress baseline systemic AVP levels. These findings have direct implications in the targeting of AT2R for disorders of AVP secretion and also for the alleviation of high blood pressure.

  17. Synaptic synthesis, dephosphorylation, and degradation: a novel paradigm for an activity-dependent neuronal control of CDKL5.

    Science.gov (United States)

    La Montanara, Paolo; Rusconi, Laura; Locarno, Albina; Forti, Lia; Barbiero, Isabella; Tramarin, Marco; Chandola, Chetan; Kilstrup-Nielsen, Charlotte; Landsberger, Nicoletta

    2015-02-13

    Mutations in the X-linked CDKL5 (cyclin-dependent kinase-like 5) gene have been associated with several forms of neurodevelopmental disorders, including atypical Rett syndrome, autism spectrum disorders, and early infantile epileptic encephalopathy. Accordingly, loss of CDKL5 in mice results in autistic-like features and impaired neuronal communication. Although the biological functions of CDKL5 remain largely unknown, recent pieces of evidence suggest that CDKL5 is involved in neuronal plasticity. Herein, we show that, at all stages of development, neuronal depolarization induces a rapid increase in CDKL5 levels, mostly mediated by extrasomatic synthesis. In young neurons, this induction is prolonged, whereas in more mature neurons, NMDA receptor stimulation induces a protein phosphatase 1-dependent dephosphorylation of CDKL5 that is mandatory for its proteasome-dependent degradation. As a corollary, neuronal activity leads to a prolonged induction of CDKL5 levels in immature neurons but to a short lasting increase of the kinase in mature neurons. Recent results demonstrate that many genes associated with autism spectrum disorders are crucial components of the activity-dependent signaling networks regulating the composition, shape, and strength of the synapse. Thus, we speculate that CDKL5 deficiency disrupts activity-dependent signaling and the consequent synapse development, maturation, and refinement. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  18. CNTF-ACM promotes mitochondrial respiration and oxidative stress in cortical neurons through upregulating L-type calcium channel activity.

    Science.gov (United States)

    Sun, Meiqun; Liu, Hongli; Xu, Huanbai; Wang, Hongtao; Wang, Xiaojing

    2016-09-01

    A specialized culture medium termed ciliary neurotrophic factor-treated astrocyte-conditioned medium (CNTF-ACM) allows investigators to assess the peripheral effects of CNTF-induced activated astrocytes upon cultured neurons. CNTF-ACM has been shown to upregulate neuronal L-type calcium channel current activity, which has been previously linked to changes in mitochondrial respiration and oxidative stress. Therefore, the aim of this study was to evaluate CNTF-ACM's effects upon mitochondrial respiration and oxidative stress in rat cortical neurons. Cortical neurons, CNTF-ACM, and untreated control astrocyte-conditioned medium (UC-ACM) were prepared from neonatal Sprague-Dawley rat cortical tissue. Neurons were cultured in either CNTF-ACM or UC-ACM for a 48-h period. Changes in the following parameters before and after treatment with the L-type calcium channel blocker isradipine were assessed: (i) intracellular calcium levels, (ii) mitochondrial membrane potential (ΔΨm), (iii) oxygen consumption rate (OCR) and adenosine triphosphate (ATP) formation, (iv) intracellular nitric oxide (NO) levels, (v) mitochondrial reactive oxygen species (ROS) production, and (vi) susceptibility to the mitochondrial complex I toxin rotenone. CNTF-ACM neurons displayed the following significant changes relative to UC-ACM neurons: (i) increased intracellular calcium levels (p ACM (p ACM promotes mitochondrial respiration and oxidative stress in cortical neurons through elevating L-type calcium channel activity.

  19. Piezo Is Essential for Amiloride-Sensitive Stretch-Activated Mechanotransduction in Larval Drosophila Dorsal Bipolar Dendritic Sensory Neurons.

    Science.gov (United States)

    Suslak, Thomas J; Watson, Sonia; Thompson, Karen J; Shenton, Fiona C; Bewick, Guy S; Armstrong, J Douglas; Jarman, Andrew P

    2015-01-01

    Stretch-activated afferent neurons, such as those of mammalian muscle spindles, are essential for proprioception and motor co-ordination, but the underlying mechanisms of mechanotransduction are poorly understood. The dorsal bipolar dendritic (dbd) sensory neurons are putative stretch receptors in the Drosophila larval body wall. We have developed an in vivo protocol to obtain receptor potential recordings from intact dbd neurons in response to stretch. Receptor potential changes in dbd neurons in response to stretch showed a complex, dynamic profile with similar characteristics to those previously observed for mammalian muscle spindles. These profiles were reproduced by a general in silico model of stretch-activated neurons. This in silico model predicts an essential role for a mechanosensory cation channel (MSC) in all aspects of receptor potential generation. Using pharmacological and genetic techniques, we identified the mechanosensory channel, DmPiezo, in this functional role in dbd neurons, with TRPA1 playing a subsidiary role. We also show that rat muscle spindles exhibit a ruthenium red-sensitive current, but found no expression evidence to suggest that this corresponds to Piezo activity. In summary, we show that the dbd neuron is a stretch receptor and demonstrate that this neuron is a tractable model for investigating mechanisms of mechanotransduction.

  20. Lévy noise improves the electrical activity in a neuron under electromagnetic radiation.

    Science.gov (United States)

    Wu, Juan; Xu, Yong; Ma, Jun

    2017-01-01

    As the fluctuations of the internal bioelectricity of nervous system is various and complex, the external electromagnetic radiation induced by magnet flux on membrane can be described by the non-Gaussian type distribution of Lévy noise. Thus, the electrical activities in an improved Hindmarsh-Rose model excited by the external electromagnetic radiation of Lévy noise are investigated and some interesting modes of the electrical activities are exhibited. The external electromagnetic radiation of Lévy noise leads to the mode transition of the electrical activities and spatial phase, such as from the rest state to the firing state, from the spiking state to the spiking state with more spikes, and from the spiking state to the bursting state. Then the time points of the firing state versus Lévy noise intensity are depicted. The increasing of Lévy noise intensity heightens the neuron firing. Also the stationary probability distribution functions of the membrane potential of the neuron induced by the external electromagnetic radiation of Lévy noise with different intensity, stability index and skewness papremeters are analyzed. Moreover, through the positive largest Lyapunov exponent, the parameter regions of chaotic electrical mode of the neuron induced by the external electromagnetic radiation of Lévy noise distribution are detected.

  1. Integrated and automated data analysis for neuronal activation studies using positron emission tomography. Methodology and applications

    International Nuclear Information System (INIS)

    Minoshima, Satoshi; Arimizu, Noboru; Koeppe, R.A.; Kuhl, D.E.

    1994-01-01

    A data analysis method was developed for neuronal activation studies using [ 15 O] water positron emission tomography (PET). The method consists of several procedures including intra-subject head motion correction (co-registration), detection of the mid-sagittal plane of the brain, detection of the intercommissural (AC-PC) line, linear scaling and non-linear warping for anatomical standardization, pixel-by-pixel statistical analysis, and data display. All steps are performed in three dimensions and are fully automated. Each step was validated using a brain phantom, computer simulations, and data from human subjects, demonstrating accuracy and reliability of the procedure. The method was applied to human neuronal activation studies using vibratory and visual stimulations. The method detected significant blood flow increases in the primary sensory cortices as well as in other regions such as the secondary sensory cortex and cerebellum. The proposed method should enhance application of PET neuronal activation studies to the investigation of higher-order human brain functions. (author) 38 refs

  2. Activity-dependent switch of GABAergic inhibition into glutamatergic excitation in astrocyte-neuron networks.

    Science.gov (United States)

    Perea, Gertrudis; Gómez, Ricardo; Mederos, Sara; Covelo, Ana; Ballesteros, Jesús J; Schlosser, Laura; Hernández-Vivanco, Alicia; Martín-Fernández, Mario; Quintana, Ruth; Rayan, Abdelrahman; Díez, Adolfo; Fuenzalida, Marco; Agarwal, Amit; Bergles, Dwight E; Bettler, Bernhard; Manahan-Vaughan, Denise; Martín, Eduardo D; Kirchhoff, Frank; Araque, Alfonso

    2016-12-24

    Interneurons are critical for proper neural network function and can activate Ca 2+ signaling in astrocytes. However, the impact of the interneuron-astrocyte signaling into neuronal network operation remains unknown. Using the simplest hippocampal Astrocyte-Neuron network, i.e., GABAergic interneuron, pyramidal neuron, single CA3-CA1 glutamatergic synapse, and astrocytes, we found that interneuron-astrocyte signaling dynamically affected excitatory neurotransmission in an activity- and time-dependent manner, and determined the sign (inhibition vs potentiation) of the GABA-mediated effects. While synaptic inhibition was mediated by GABA A receptors, potentiation involved astrocyte GABA B receptors, astrocytic glutamate release, and presynaptic metabotropic glutamate receptors. Using conditional astrocyte-specific GABA B receptor ( Gabbr1 ) knockout mice, we confirmed the glial source of the interneuron-induced potentiation, and demonstrated the involvement of astrocytes in hippocampal theta and gamma oscillations in vivo. Therefore, astrocytes decode interneuron activity and transform inhibitory into excitatory signals, contributing to the emergence of novel network properties resulting from the interneuron-astrocyte interplay.

  3. TLX activates MASH1 for induction of neuronal lineage commitment of adult hippocampal neuroprogenitors.

    Science.gov (United States)

    Elmi, Muna; Matsumoto, Yoshiki; Zeng, Zhao-jun; Lakshminarasimhan, Pavithra; Yang, Weiwen; Uemura, Akiyoshi; Nishikawa, Shin-ichi; Moshiri, Alicia; Tajima, Nobuyoshi; Agren, Hans; Funa, Keiko

    2010-10-01

    The orphan nuclear receptor TLX has been proposed to act as a repressor of cell cycle inhibitors to maintain the neural stem cells in an undifferentiated state, and prevents commitment into astrocyte lineages. However, little is known about the mechanism of TLX in neuronal lineage commitment and differentiation. A majority of adult rat hippocampus-derived progenitors (AHPs) cultured in the presence of FGF express a high level of TLX and a fraction of these cells also express the proneural gene MASH1. Upon FGF withdrawal, TLX rapidly decreased, while MASH1 was intensely expressed within 1h, decreasing gradually to disappear at 24h. Adenoviral transduction of TLX in AHP cells in the absence of FGF transiently increased cell proliferation, however, later resulted in neuronal differentiation by inducing MASH1, Neurogenin1, DCX, and MAP2ab. Furthermore, TLX directly targets and activates the MASH1 promoter through interaction with Sp1, recruiting co-activators whereas dismissing the co-repressor HDAC4. Conversely, silencing of TLX in AHPs decreased beta-III tubulin and DCX expression and promoted glial differentiation. Our results thus suggest that TLX not only acts as a repressor of cell cycle and glial differentiation but also activates neuronal lineage commitment in AHPs. Copyright 2010 Elsevier Inc. All rights reserved.

  4. Lévy noise improves the electrical activity in a neuron under electromagnetic radiation.

    Directory of Open Access Journals (Sweden)

    Juan Wu

    Full Text Available As the fluctuations of the internal bioelectricity of nervous system is various and complex, the external electromagnetic radiation induced by magnet flux on membrane can be described by the non-Gaussian type distribution of Lévy noise. Thus, the electrical activities in an improved Hindmarsh-Rose model excited by the external electromagnetic radiation of Lévy noise are investigated and some interesting modes of the electrical activities are exhibited. The external electromagnetic radiation of Lévy noise leads to the mode transition of the electrical activities and spatial phase, such as from the rest state to the firing state, from the spiking state to the spiking state with more spikes, and from the spiking state to the bursting state. Then the time points of the firing state versus Lévy noise intensity are depicted. The increasing of Lévy noise intensity heightens the neuron firing. Also the stationary probability distribution functions of the membrane potential of the neuron induced by the external electromagnetic radiation of Lévy noise with different intensity, stability index and skewness papremeters are analyzed. Moreover, through the positive largest Lyapunov exponent, the parameter regions of chaotic electrical mode of the neuron induced by the external electromagnetic radiation of Lévy noise distribution are detected.

  5. Lifting the veil on the dynamics of neuronal activities evoked by transcranial magnetic stimulation

    Science.gov (United States)

    Li, Bingshuo; Virtanen, Juha P; Oeltermann, Axel; Schwarz, Cornelius; Giese, Martin A; Ziemann, Ulf

    2017-01-01

    Transcranial magnetic stimulation (TMS) is a widely used non-invasive tool to study and modulate human brain functions. However, TMS-evoked activity of individual neurons has remained largely inaccessible due to the large TMS-induced electromagnetic fields. Here, we present a general method providing direct in vivo electrophysiological access to TMS-evoked neuronal activity 0.8–1 ms after TMS onset. We translated human single-pulse TMS to rodents and unveiled time-grained evoked activities of motor cortex layer V neurons that show high-frequency spiking within the first 6 ms depending on TMS-induced current orientation and a multiphasic spike-rhythm alternating between excitation and inhibition in the 6–300 ms epoch, all of which can be linked to various human TMS responses recorded at the level of spinal cord and muscles. The advance here facilitates a new level of insight into the TMS-brain interaction that is vital for developing this non-invasive tool to purposefully explore and effectively treat the human brain. PMID:29165241

  6. A portable telemetry system for brain stimulation and neuronal activity recording in freely behaving small animals.

    Science.gov (United States)

    Ye, Xuesong; Wang, Peng; Liu, Jun; Zhang, Shaomin; Jiang, Jun; Wang, Qingbo; Chen, Weidong; Zheng, Xiaoxiang

    2008-09-30

    A portable multi-channel telemetry system which can be used for brain stimulation and neuronal activity recording in freely behaving small animals is described here. This system consists of three major components of headstage, backpack and portable Personal Digital Assistant (PDA). The headstage contains high precision instrument amplifiers with high input impedance. The backpack is comprised of two parts: (1) a main board (size: 36 mm x 22 mm x 3.5 mm and weight: 40 g with batteries, 20 g without), with current/voltage stimulator and special circuit suitable for neuronal activity recording and (2) and a bluetooth transceiver, with a high data transmission rate up to 70 kb/s, suitable for downloading stimulation commands and uploading acquired data. We recorded neuronal activities of the primary motor area of a freely behaving rat with 12-bit resolution at 12 k samples/s. The recorded data and analysis results showed that the system was successful by comparing with the commercial equipment Cerebus 128-Channel Data Acquisition System (Cyberkinetics Inc.). Using the PDA, we can control stimulation and recording. It provides a flexible method to do some research work in the circumstances where other approaches would be difficult or impossible.

  7. Simultaneous activation of mitophagy and autophagy by staurosporine protects against dopaminergic neuronal cell death.

    Science.gov (United States)

    Ha, Ji-Young; Kim, Ji-Soo; Kim, Seo-Eun; Son, Jin H

    2014-02-21

    Abnormal autophagy is frequently observed during dopaminergic neurodegeneration in Parkinson's disease (PD). However, it is not yet firmly established whether active autophagy is beneficial or pathogenic with respect to dopaminergic cell loss. Staurosporine, a common inducer of apoptosis, is often used in mechanistic studies of dopaminergic cell death. Here we report that staurosporine activates both autophagy and mitophagy simultaneously during dopaminergic neuronal cell death, and evaluate the physiological significance of these processes during cell death. First, staurosporine treatment resulted in induction of autophagy in more than 75% of apoptotic cells. Pharmacological inhibition of autophagy by bafilomycin A1 decreased significantly cell viability. In addition, staurosporine treatment resulted in activation of the PINK1-Parkin mitophagy pathway, of which deficit underlies some familial cases of PD, in the dopaminergic neuronal cell line, SN4741. The genetic blockade of this pathway by PINK1 null mutation also dramatically increased staurosporine-induced cell death. Taken together, our data suggest that staurosporine induces both mitophagy and autophagy, and that these pathways exert a significant neuroprotective effect, rather than a contribution to autophagic cell death. This model system may therefore be useful for elucidating the mechanisms underlying crosstalk between autophagy, mitophagy, and cell death in dopaminergic neurons. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  8. Lifting the veil on the dynamics of neuronal activities evoked by transcranial magnetic stimulation.

    Science.gov (United States)

    Li, Bingshuo; Virtanen, Juha P; Oeltermann, Axel; Schwarz, Cornelius; Giese, Martin A; Ziemann, Ulf; Benali, Alia

    2017-11-22

    Transcranial magnetic stimulation (TMS) is a widely used non-invasive tool to study and modulate human brain functions. However, TMS-evoked activity of individual neurons has remained largely inaccessible due to the large TMS-induced electromagnetic fields. Here, we present a general method providing direct in vivo electrophysiological access to TMS-evoked neuronal activity 0.8-1 ms after TMS onset. We translated human single-pulse TMS to rodents and unveiled time-grained evoked activities of motor cortex layer V neurons that show high-frequency spiking within the first 6 ms depending on TMS-induced current orientation and a multiphasic spike-rhythm alternating between excitation and inhibition in the 6-300 ms epoch, all of which can be linked to various human TMS responses recorded at the level of spinal cord and muscles. The advance here facilitates a new level of insight into the TMS-brain interaction that is vital for developing this non-invasive tool to purposefully explore and effectively treat the human brain.

  9. Transcription factor activating protein 2 beta (TFAP2B) mediates noradrenergic neuronal differentiation in neuroblastoma.

    Science.gov (United States)

    Ikram, Fakhera; Ackermann, Sandra; Kahlert, Yvonne; Volland, Ruth; Roels, Frederik; Engesser, Anne; Hertwig, Falk; Kocak, Hayriye; Hero, Barbara; Dreidax, Daniel; Henrich, Kai-Oliver; Berthold, Frank; Nürnberg, Peter; Westermann, Frank; Fischer, Matthias

    2016-02-01

    Neuroblastoma is an embryonal pediatric tumor that originates from the developing sympathetic nervous system and shows a broad range of clinical behavior, ranging from fatal progression to differentiation into benign ganglioneuroma. In experimental neuroblastoma systems, retinoic acid (RA) effectively induces neuronal differentiation, and RA treatment has been therefore integrated in current therapies. However, the molecular mechanisms underlying differentiation are still poorly understood. We here investigated the role of transcription factor activating protein 2 beta (TFAP2B), a key factor in sympathetic nervous system development, in neuroblastoma pathogenesis and differentiation. Microarray analyses of primary neuroblastomas (n = 649) demonstrated that low TFAP2B expression was significantly associated with unfavorable prognostic markers as well as adverse patient outcome. We also found that low TFAP2B expression was strongly associated with CpG methylation of the TFAP2B locus in primary neuroblastomas (n = 105) and demethylation with 5-aza-2'-deoxycytidine resulted in induction of TFAP2B expression in vitro, suggesting that TFAP2B is silenced by genomic methylation. Tetracycline inducible re-expression of TFAP2B in IMR-32 and SH-EP neuroblastoma cells significantly impaired proliferation and cell cycle progression. In IMR-32 cells, TFAP2B induced neuronal differentiation, which was accompanied by up-regulation of the catecholamine biosynthesizing enzyme genes DBH and TH, and down-regulation of MYCN and REST, a master repressor of neuronal genes. By contrast, knockdown of TFAP2B by lentiviral transduction of shRNAs abrogated RA-induced neuronal differentiation of SH-SY5Y and SK-N-BE(2)c neuroblastoma cells almost completely. Taken together, our results suggest that TFAP2B is playing a vital role in retaining RA responsiveness and mediating noradrenergic neuronal differentiation in neuroblastoma. Copyright © 2015 Federation of European Biochemical Societies

  10. Interplay between Structure and Charge as a Key to Allosteric Modulation of Human 20S Proteasome by the Basic Fragment of HIV-1 Tat Protein.

    Directory of Open Access Journals (Sweden)

    Przemysław Karpowicz

    Full Text Available The proteasome is a giant protease responsible for degradation of the majority of cytosolic proteins. Competitive inhibitors of the proteasome are used against aggressive blood cancers. However, broadening the use of proteasome-targeting drugs requires new mechanistic approaches to the enzyme's inhibition. In our previous studies we described Tat1 peptide, an allosteric inhibitor of the proteasome derived from a fragment of the basic domain of HIV-Tat1 protein. Here, we attempted to dissect the structural determinants of the proteasome inhibition by Tat1. Single- and multiple- alanine walking scans were performed. Tat1 analogs with stabilized beta-turn conformation at positions 4-5 and 8-9, pointed out by the molecular dynamics modeling and the alanine scan, were synthesized. Structure of Tat1 analogs were analyzed by circular dichroism, Fourier transform infrared and nuclear magnetic resonance spectroscopy studies, supplemented by molecular dynamics simulations. Biological activity tests and structural studies revealed that high flexibility and exposed positive charge are hallmarks of Tat1 peptide. Interestingly, stabilization of a beta-turn at the 8-9 position was necessary to significantly improve the inhibitory potency.

  11. Effect of agmatine on locus coeruleus neuron activity: possible involvement of nitric oxide

    Science.gov (United States)

    Ruiz-Durántez, Eduardo; Ruiz-Ortega, José A; Pineda, Joseba; Ugedo, Luisa

    2002-01-01

    To investigate whether agmatine (the proposed endogenous ligand for imidazoline receptors) controls locus coeruleus neuron activity and to elucidate its mechanism of action, we used single-unit extracellular recording techniques in anaesthetized rats. Agmatine (10, 20 and 40 μg, i.c.v.) increased in a dose-related manner the firing rate of locus coeruleus neurons (maximal increase: 95±13% at 40 μg). I1-imidazoline receptor ligands stimulate locus coeruleus neuron activity through an indirect mechanism originated in the paragigantocellularis nucleus via excitatory amino acids. However, neither electrolytic lesions of the paragigantocellularis nucleus nor pretreatment with the excitatory amino acid antagonist kynurenic acid (1 μmol, i.c.v.) modified agmatine effect (10 μg, i.c.v.). After agmatine administration (20 μg, i.c.v.), dose-response curves for the effect of clonidine (0.625 – 10 μg kg−1 i.v.) or morphine (0.3 – 4.8 mg kg−1 i.v.) on locus coeruleus neurons were not different from those obta