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  1. Norepinephrine versus dopamine and their interaction in modulating synaptic function in the prefrontal cortex.

    Science.gov (United States)

    Xing, Bo; Li, Yan-Chun; Gao, Wen-Jun

    2016-06-15

    Among the neuromodulators that regulate prefrontal cortical circuit function, the catecholamine transmitters norepinephrine (NE) and dopamine (DA) stand out as powerful players in working memory and attention. Perturbation of either NE or DA signaling is implicated in the pathogenesis of several neuropsychiatric disorders, including attention deficit hyperactivity disorder (ADHD), post-traumatic stress disorder (PTSD), schizophrenia, and drug addiction. Although the precise mechanisms employed by NE and DA to cooperatively control prefrontal functions are not fully understood, emerging research indicates that both transmitters regulate electrical and biochemical aspects of neuronal function by modulating convergent ionic and synaptic signaling in the prefrontal cortex (PFC). This review summarizes previous studies that investigated the effects of both NE and DA on excitatory and inhibitory transmissions in the prefrontal cortical circuitry. Specifically, we focus on the functional interaction between NE and DA in prefrontal cortical local circuitry, synaptic integration, signaling pathways, and receptor properties. Although it is clear that both NE and DA innervate the PFC extensively and modulate synaptic function by activating distinctly different receptor subtypes and signaling pathways, it remains unclear how these two systems coordinate their actions to optimize PFC function for appropriate behavior. Throughout this review, we provide perspectives and highlight several critical topics for future studies. This article is part of a Special Issue entitled SI: Noradrenergic System. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Cerebellar Norepinephrine Modulates Learning of Delay Classical Eyeblink Conditioning: Evidence for Post-Synaptic Signaling via PKA

    Science.gov (United States)

    Fister, Mathew; Bickford, Paula C.; Cartford, M. Claire; Samec, Amy

    2004-01-01

    The neurotransmitter norepinephrine (NE) has been shown to modulate cerebellar-dependent learning and memory. Lesions of the nucleus locus coeruleus or systemic blockade of noradrenergic receptors has been shown to delay the acquisition of several cerebellar-dependent learning tasks. To date, no studies have shown a direct involvement of…

  3. Role of calcium in phosphoinositide metabolism and inhibition of norepinephrine transport into synaptic vesicles by amphetamine analogs

    International Nuclear Information System (INIS)

    Knepper, S.M.

    1985-01-01

    Norepinephrine-(NE) and calcium ionophore A23187-stimulated phosphoinositide (PIn) metabolism in rat brain slices was studied under varying calcium conditions. Tissue was labelled with 3 H-myo-inositol and 3 H-inositol phosphates (IPn), products of PIn metabolism were measured. In the absence of media calcium the response to NE was decreased while that to A23187 was little affected A23187 can release calcium from intracellular stores. Basal and stimulated accumulation of 3 H-IPn was reversibly antagonized with EGTA by addition of calcium. Using calcium buffers, approximately 10 -7 M free calcium was required to support hydrolysis. Free intracellular calcium is maintained at approximately this level. Thus calcium is required for PIn hydrolysis but appears to play a permissive role, basal levels being sufficient to support metabolism. Conformationally-defined (rigid) and -restricted (semi-rigid) analogs of the most stable conformations of amphetamine, antiperiplanar (exo) and gauche (endo), were utilized to probe the conformational requirements of vesicular NE transport. Analogs tested were 2-aminotetralin (2AT), 3-methyltetrahydroisoquinoline, anti- and syn-9-aminobenzobicyclo[2.2.1]heptene, and endo and exo conformers of 2-aminobenzobicyclo[2.2.1]heptene and 2-aminobenzobicyclo[2.2.2]octene

  4. Characterizing synaptic protein development in human visual cortex enables alignment of synaptic age with rat visual cortex

    Directory of Open Access Journals (Sweden)

    Joshua G.A Pinto

    2015-02-01

    Full Text Available Although many potential neuroplasticity based therapies have been developed in the lab, few have translated into established clinical treatments for human neurologic or neuropsychiatric diseases. Animal models, especially of the visual system, have shaped our understanding of neuroplasticity by characterizing the mechanisms that promote neural changes and defining timing of the sensitive period. The lack of knowledge about development of synaptic plasticity mechanisms in human cortex, and about alignment of synaptic age between animals and humans, has limited translation of neuroplasticity therapies. In this study, we quantified expression of a set of highly conserved pre- and post-synaptic proteins (Synapsin, Synaptophysin, PSD-95, Gephyrin and found that synaptic development in human primary visual cortex continues into late childhood. Indeed, this is many years longer than suggested by neuroanatomical studies and points to a prolonged sensitive period for plasticity in human sensory cortex. In addition, during childhood we found waves of inter-individual variability that are different for the 4 proteins and include a stage during early development (<1 year when only Gephyrin has high inter-individual variability. We also found that pre- and post-synaptic protein balances develop quickly, suggesting that maturation of certain synaptic functions happens within the first year or two of life. A multidimensional analysis (principle component analysis showed that most of the variance was captured by the sum of the 4 synaptic proteins. We used that sum to compare development of human and rat visual cortex and identified a simple linear equation that provides robust alignment of synaptic age between humans and rats. Alignment of synaptic ages is important for age-appropriate targeting and effective translation of neuroplasticity therapies from the lab to the clinic.

  5. Characterizing synaptic protein development in human visual cortex enables alignment of synaptic age with rat visual cortex

    Science.gov (United States)

    Pinto, Joshua G. A.; Jones, David G.; Williams, C. Kate; Murphy, Kathryn M.

    2015-01-01

    Although many potential neuroplasticity based therapies have been developed in the lab, few have translated into established clinical treatments for human neurologic or neuropsychiatric diseases. Animal models, especially of the visual system, have shaped our understanding of neuroplasticity by characterizing the mechanisms that promote neural changes and defining timing of the sensitive period. The lack of knowledge about development of synaptic plasticity mechanisms in human cortex, and about alignment of synaptic age between animals and humans, has limited translation of neuroplasticity therapies. In this study, we quantified expression of a set of highly conserved pre- and post-synaptic proteins (Synapsin, Synaptophysin, PSD-95, Gephyrin) and found that synaptic development in human primary visual cortex (V1) continues into late childhood. Indeed, this is many years longer than suggested by neuroanatomical studies and points to a prolonged sensitive period for plasticity in human sensory cortex. In addition, during childhood we found waves of inter-individual variability that are different for the four proteins and include a stage during early development (visual cortex and identified a simple linear equation that provides robust alignment of synaptic age between humans and rats. Alignment of synaptic ages is important for age-appropriate targeting and effective translation of neuroplasticity therapies from the lab to the clinic. PMID:25729353

  6. Volterra representation enables modeling of complex synaptic nonlinear dynamics in large-scale simulations.

    Science.gov (United States)

    Hu, Eric Y; Bouteiller, Jean-Marie C; Song, Dong; Baudry, Michel; Berger, Theodore W

    2015-01-01

    Chemical synapses are comprised of a wide collection of intricate signaling pathways involving complex dynamics. These mechanisms are often reduced to simple spikes or exponential representations in order to enable computer simulations at higher spatial levels of complexity. However, these representations cannot capture important nonlinear dynamics found in synaptic transmission. Here, we propose an input-output (IO) synapse model capable of generating complex nonlinear dynamics while maintaining low computational complexity. This IO synapse model is an extension of a detailed mechanistic glutamatergic synapse model capable of capturing the input-output relationships of the mechanistic model using the Volterra functional power series. We demonstrate that the IO synapse model is able to successfully track the nonlinear dynamics of the synapse up to the third order with high accuracy. We also evaluate the accuracy of the IO synapse model at different input frequencies and compared its performance with that of kinetic models in compartmental neuron models. Our results demonstrate that the IO synapse model is capable of efficiently replicating complex nonlinear dynamics that were represented in the original mechanistic model and provide a method to replicate complex and diverse synaptic transmission within neuron network simulations.

  7. Characterizing synaptic protein development in human visual cortex enables alignment of synaptic age with rat visual cortex

    OpenAIRE

    Pinto, Joshua G. A.; Jones, David G.; Williams, C. Kate; Murphy, Kathryn M.

    2015-01-01

    Although many potential neuroplasticity based therapies have been developed in the lab, few have translated into established clinical treatments for human neurologic or neuropsychiatric diseases. Animal models, especially of the visual system, have shaped our understanding of neuroplasticity by characterizing the mechanisms that promote neural changes and defining timing of the sensitive period. The lack of knowledge about development of synaptic plasticity mechanisms in human cortex, and abo...

  8. Characterizing synaptic protein development in human visual cortex enables alignment of synaptic age with rat visual cortex

    OpenAIRE

    Joshua G.A Pinto; David G Jones; Kate eWilliams; Kathryn M Murphy; Kathryn M Murphy

    2015-01-01

    Although many potential neuroplasticity based therapies have been developed in the lab, few have translated into established clinical treatments for human neurologic or neuropsychiatric diseases. Animal models, especially of the visual system, have shaped our understanding of neuroplasticity by characterizing the mechanisms that promote neural changes and defining timing of the sensitive period. The lack of knowledge about development of synaptic plasticity mechanisms in human cortex, and a...

  9. Synaptic scaling enables dynamically distinct short- and long-term memory formation.

    Directory of Open Access Journals (Sweden)

    Christian Tetzlaff

    2013-10-01

    Full Text Available Memory storage in the brain relies on mechanisms acting on time scales from minutes, for long-term synaptic potentiation, to days, for memory consolidation. During such processes, neural circuits distinguish synapses relevant for forming a long-term storage, which are consolidated, from synapses of short-term storage, which fade. How time scale integration and synaptic differentiation is simultaneously achieved remains unclear. Here we show that synaptic scaling - a slow process usually associated with the maintenance of activity homeostasis - combined with synaptic plasticity may simultaneously achieve both, thereby providing a natural separation of short- from long-term storage. The interaction between plasticity and scaling provides also an explanation for an established paradox where memory consolidation critically depends on the exact order of learning and recall. These results indicate that scaling may be fundamental for stabilizing memories, providing a dynamic link between early and late memory formation processes.

  10. Synaptic scaling enables dynamically distinct short- and long-term memory formation.

    Science.gov (United States)

    Tetzlaff, Christian; Kolodziejski, Christoph; Timme, Marc; Tsodyks, Misha; Wörgötter, Florentin

    2013-10-01

    Memory storage in the brain relies on mechanisms acting on time scales from minutes, for long-term synaptic potentiation, to days, for memory consolidation. During such processes, neural circuits distinguish synapses relevant for forming a long-term storage, which are consolidated, from synapses of short-term storage, which fade. How time scale integration and synaptic differentiation is simultaneously achieved remains unclear. Here we show that synaptic scaling - a slow process usually associated with the maintenance of activity homeostasis - combined with synaptic plasticity may simultaneously achieve both, thereby providing a natural separation of short- from long-term storage. The interaction between plasticity and scaling provides also an explanation for an established paradox where memory consolidation critically depends on the exact order of learning and recall. These results indicate that scaling may be fundamental for stabilizing memories, providing a dynamic link between early and late memory formation processes.

  11. Localization of Presynaptic Plasticity Mechanisms Enables Functional Independence of Synaptic and Ectopic Transmission in the Cerebellum

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    Katharine L. Dobson

    2015-01-01

    Full Text Available In the cerebellar molecular layer parallel fibre terminals release glutamate from both the active zone and from extrasynaptic “ectopic” sites. Ectopic release mediates transmission to the Bergmann glia that ensheathe the synapse, activating Ca2+-permeable AMPA receptors and glutamate transporters. Parallel fibre terminals exhibit several forms of presynaptic plasticity, including cAMP-dependent long-term potentiation and endocannabinoid-dependent long-term depression, but it is not known whether these presynaptic forms of long-term plasticity also influence ectopic transmission to Bergmann glia. Stimulation of parallel fibre inputs at 16 Hz evoked LTP of synaptic transmission, but LTD of ectopic transmission. Pharmacological activation of adenylyl cyclase by forskolin caused LTP at Purkinje neurons, but only transient potentiation at Bergmann glia, reinforcing the concept that ectopic sites lack the capacity to express sustained cAMP-dependent potentiation. Activation of mGluR1 caused depression of synaptic transmission via retrograde endocannabinoid signalling but had no significant effect at ectopic sites. In contrast, activation of NMDA receptors suppressed both synaptic and ectopic transmission. The results suggest that the signalling mechanisms for presynaptic LTP and retrograde depression by endocannabinoids are restricted to the active zone at parallel fibre synapses, allowing independent modulation of synaptic transmission to Purkinje neurons and ectopic transmission to Bergmann glia.

  12. Neurokinin-1 enables measles virus trans-synaptic spread in neurons

    International Nuclear Information System (INIS)

    Makhortova, Nina R.; Askovich, Peter; Patterson, Catherine E.; Gechman, Lisa A.; Gerard, Norma P.; Rall, Glenn F.

    2007-01-01

    Measles virus (MV), a morbillivirus that remains a significant human pathogen, can infect the central nervous system, resulting in rare but often fatal diseases, such as subacute sclerosing panencephalitis. Previous work demonstrated that MV was transmitted trans-synaptically and that, while a cellular receptor for the hemagglutinin (H) protein was required for MV entry, it was dispensable for subsequent cell-to-cell spread. Here, we explored what role the other envelope protein, fusion (F), played in trans-synaptic transport. We made the following observations: (1) MV-F expression in infected neurons was similar to that seen in infected fibroblasts; (2) fusion inhibitory peptide (FIP), an inhibitor of MV fusion, prevented both infection and spread in primary neurons; (3) Substance P, a neurotransmitter with the same active site as FIP, also blocked neuronal MV spread; and (4) both genetic deletion and pharmacological inhibition of the Substance P receptor, neurokinin-1 (NK-1), reduced infection of susceptible mice. Together, these data implicate a role for NK-1 in MV CNS infection and spread, perhaps serving as an MV-F receptor or co-receptor on neurons

  13. Is a 4-bit synaptic weight resolution enough? - constraints on enabling spike-timing dependent plasticity in neuromorphic hardware.

    Science.gov (United States)

    Pfeil, Thomas; Potjans, Tobias C; Schrader, Sven; Potjans, Wiebke; Schemmel, Johannes; Diesmann, Markus; Meier, Karlheinz

    2012-01-01

    Large-scale neuromorphic hardware systems typically bear the trade-off between detail level and required chip resources. Especially when implementing spike-timing dependent plasticity, reduction in resources leads to limitations as compared to floating point precision. By design, a natural modification that saves resources would be reducing synaptic weight resolution. In this study, we give an estimate for the impact of synaptic weight discretization on different levels, ranging from random walks of individual weights to computer simulations of spiking neural networks. The FACETS wafer-scale hardware system offers a 4-bit resolution of synaptic weights, which is shown to be sufficient within the scope of our network benchmark. Our findings indicate that increasing the resolution may not even be useful in light of further restrictions of customized mixed-signal synapses. In addition, variations due to production imperfections are investigated and shown to be uncritical in the context of the presented study. Our results represent a general framework for setting up and configuring hardware-constrained synapses. We suggest how weight discretization could be considered for other backends dedicated to large-scale simulations. Thus, our proposition of a good hardware verification practice may rise synergy effects between hardware developers and neuroscientists.

  14. LTD windows of the STDP learning rule and synaptic connections having a large transmission delay enable robust sequence learning amid background noise.

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    Hayashi, Hatsuo; Igarashi, Jun

    2009-06-01

    Spike-timing-dependent synaptic plasticity (STDP) is a simple and effective learning rule for sequence learning. However, synapses being subject to STDP rules are readily influenced in noisy circumstances because synaptic conductances are modified by pre- and postsynaptic spikes elicited within a few tens of milliseconds, regardless of whether those spikes convey information or not. Noisy firing existing everywhere in the brain may induce irrelevant enhancement of synaptic connections through STDP rules and would result in uncertain memory encoding and obscure memory patterns. We will here show that the LTD windows of the STDP rules enable robust sequence learning amid background noise in cooperation with a large signal transmission delay between neurons and a theta rhythm, using a network model of the entorhinal cortex layer II with entorhinal-hippocampal loop connections. The important element of the present model for robust sequence learning amid background noise is the symmetric STDP rule having LTD windows on both sides of the LTP window, in addition to the loop connections having a large signal transmission delay and the theta rhythm pacing activities of stellate cells. Above all, the LTD window in the range of positive spike-timing is important to prevent influences of noise with the progress of sequence learning.

  15. Is a 4-bit synaptic weight resolution enough? - Constraints on enabling spike-timing dependent plasticity in neuromorphic hardware

    Directory of Open Access Journals (Sweden)

    Thomas ePfeil

    2012-07-01

    Full Text Available Large-scale neuromorphic hardware systems typically bear the trade-off be-tween detail level and required chip resources. Especially when implementingspike-timing-dependent plasticity, reduction in resources leads to limitations ascompared to floating point precision. By design, a natural modification that savesresources would be reducing synaptic weight resolution. In this study, we give anestimate for the impact of synaptic weight discretization on different levels, rangingfrom random walks of individual weights to computer simulations of spiking neuralnetworks. The FACETS wafer-scale hardware system offers a 4-bit resolution ofsynaptic weights, which is shown to be sufficient within the scope of our networkbenchmark. Our findings indicate that increasing the resolution may not even beuseful in light of further restrictions of customized mixed-signal synapses. In ad-dition, variations due to production imperfections are investigated and shown tobe uncritical in the context of the presented study. Our results represent a generalframework for setting up and configuring hardware-constrained synapses. We sug-gest how weight discretization could be considered for other backends dedicatedto large-scale simulations. Thus, our proposition of a good hardware verificationpractice may rise synergy effects between hardware developers and neuroscientists.

  16. EDITORIAL: Synaptic electronics Synaptic electronics

    Science.gov (United States)

    Demming, Anna; Gimzewski, James K.; Vuillaume, Dominique

    2013-09-01

    Conventional computers excel in logic and accurate scientific calculations but make hard work of open ended problems that human brains handle easily. Even von Neumann—the mathematician and polymath who first developed the programming architecture that forms the basis of today's computers—was already looking to the brain for future developments before his death in 1957 [1]. Neuromorphic computing uses approaches that better mimic the working of the human brain. Recent developments in nanotechnology are now providing structures with very accommodating properties for neuromorphic approaches. This special issue, with guest editors James K Gimzewski and Dominique Vuillaume, is devoted to research at the serendipitous interface between the two disciplines. 'Synaptic electronics', looks at artificial devices with connections that demonstrate behaviour similar to synapses in the nervous system allowing a new and more powerful approach to computing. Synapses and connecting neurons respond differently to incident signals depending on the history of signals previously experienced, ultimately leading to short term and long term memory behaviour. The basic characteristics of a synapse can be replicated with around ten simple transistors. However with the human brain having around 1011 neurons and 1015 synapses, artificial neurons and synapses from basic transistors are unlikely to accommodate the scalability required. The discovery of nanoscale elements that function as 'memristors' has provided a key tool for the implementation of synaptic connections [2]. Leon Chua first developed the concept of the 'The memristor—the missing circuit element' in 1971 [3]. In this special issue he presents a tutorial describing how memristor research has fed into our understanding of synaptic behaviour and how they can be applied in information processing [4]. He also describes, 'The new principle of local activity, which uncovers a minuscule life-enabling "Goldilocks zone", dubbed the

  17. Serotonin and Norepinephrine Reuptake Inhibitors (SNRIs)

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    Serotonin and norepinephrine reuptake inhibitors (SNRIs) Antidepressant SNRIs help relieve depression symptoms, such as irritability and sadness, ... effects they may cause. By Mayo Clinic Staff Serotonin and norepinephrine reuptake inhibitors (SNRIs) are a class ...

  18. Synaptic control of motoneuronal excitability

    DEFF Research Database (Denmark)

    Rekling, J C; Funk, G D; Bayliss, D A

    2000-01-01

    important in understanding the transformation of neural activity to motor behavior. Here, we review recent studies on the control of motoneuronal excitability, focusing on synaptic and cellular properties. We first present a background description of motoneurons: their development, anatomical organization......, and membrane properties, both passive and active. We then describe the general anatomical organization of synaptic input to motoneurons, followed by a description of the major transmitter systems that affect motoneuronal excitability, including ligands, receptor distribution, pre- and postsynaptic actions...... and norepinephrine, and neuropeptides, as well as the glutamate and GABA acting at metabotropic receptors, modulate motoneuronal excitability through pre- and postsynaptic actions. Acting principally via second messenger systems, their actions converge on common effectors, e.g., leak K(+) current, cationic inward...

  19. Cardiac norepinephrine kinetics in hypertrophic cardiomyopathy

    International Nuclear Information System (INIS)

    Brush, J.E. Jr.; Eisenhofer, G.; Garty, M.; Stull, R.; Maron, B.J.; Cannon, R.O. III; Panza, J.A.; Epstein, S.E.; Goldstein, D.S.

    1989-01-01

    We examined the uptake and release of norepinephrine in the cardiac circulation and other regional vascular beds in 11 patients with hypertrophic cardiomyopathy (HCM) and in 10 control subjects during simultaneous infusion of tracer-labeled norepinephrine and isoproterenol. Cardiac neuronal uptake of norepinephrine was assessed by comparing regional removal of tracer-labeled norepinephrine with that of tracer-labeled isoproterenol (which is not a substrate for neuronal uptake) and by the relation between production of dihydroxyphenylglycol (DHPG), an exclusively intraneuronal metabolite of norepinephrine, and regional spillover of norepinephrine. Cardiac extraction of norepinephrine averaged 59 +/- 17% in the patients with HCM, significantly less than in the control subjects (79 +/- 13%, p less than 0.05), whereas cardiac extraction of isoproterenol was similar in the two groups (13 +/- 23% versus 13 +/- 14%), indicating that neuronal uptake of norepinephrine was decreased in the patients with HCM. The cardiac arteriovenous difference in norepinephrine was significantly larger in the patients with HCM than in the control subjects (73 +/- 77 versus 13 +/- 50 pg/ml, p less than 0.05), as was the product of the arteriovenous difference in norepinephrine and coronary blood flow (7.3 +/- 7.3 versus 0.8 +/- 3.0 ng/min, p less than 0.05)

  20. Synaptic Cell Adhesion

    OpenAIRE

    Missler, Markus; Südhof, Thomas C.; Biederer, Thomas

    2012-01-01

    Chemical synapses are asymmetric intercellular junctions that mediate synaptic transmission. Synaptic junctions are organized by trans-synaptic cell adhesion molecules bridging the synaptic cleft. Synaptic cell adhesion molecules not only connect pre- and postsynaptic compartments, but also mediate trans-synaptic recognition and signaling processes that are essential for the establishment, specification, and plasticity of synapses. A growing number of synaptic cell adhesion molecules that inc...

  1. Neuromodulation, development and synaptic plasticity.

    Science.gov (United States)

    Foehring, R C; Lorenzon, N M

    1999-03-01

    We discuss parallels in the mechanisms underlying use-dependent synaptic plasticity during development and long-term potentiation (LTP) and long-term depression (LTD) in neocortical synapses. Neuromodulators, such as norepinephrine, serotonin, and acetylcholine have also been implicated in regulating both developmental plasticity and LTP/LTD. There are many potential levels of interaction between neuromodulators and plasticity. Ion channels are substrates for modulation in many cell types. We discuss examples of modulation of voltage-gated Ca2+ channels and Ca(2+)-dependent K+ channels and the consequences for neocortical pyramidal cell firing behaviour. At the time when developmental plasticity is most evident in rat cortex, the substrate for modulation is changing as the densities and relative proportions of various ion channels types are altered during ontogeny. We discuss examples of changes in K+ and Ca2+ channels and the consequence for modulation of neuronal activity.

  2. DOPA, norepinephrine, and dopamine in rat tissues

    DEFF Research Database (Denmark)

    Eldrup, E; Richter, Erik; Christensen, N J

    1989-01-01

    We studied the effect of unilateral sympathectomy on rat quadriceps and gastrocnemius muscle concentrations of endogenous dihydroxyphenylalanine (DOPA), dopamine (DA), and norepinephrine (NE) and assessed the relationships between these catecholamines in several rat tissues. Catecholamines were...

  3. PET measures of pre- and post-synaptic cardiac beta adrenergic function

    Energy Technology Data Exchange (ETDEWEB)

    Link, Jeanne M.; Stratton, John R.; Levy, Wayne; Poole, Jeanne E.; Shoner, Steven C.; Stuetzle, Werner; Caldwell, James H. E-mail: jcald@u.washington.edu

    2003-11-01

    Positron Emission Tomography was used to measure global and regional cardiac {beta}-adrenergic function in 19 normal subjects and 9 congestive heart failure patients. [{sup 11}C]-meta-hydroxyephedrine was used to image norepinephrine transporter function as an indicator of pre-synaptic function and [{sup 11}C]-CGP12177 was used to measure cell surface {beta}-receptor density as an indicator of post-synaptic function. Pre-synaptic, but not post-synaptic, function was significantly different between normals and CHF patients. Pre-synaptic function was well matched to post-synaptic function in the normal hearts but significantly different and poorly matched in the CHF patients studied. This imaging technique can help us understand regional sympathetic function in cardiac disease.

  4. Norepinephrine kinetics during insulin-induced hypoglycemia

    DEFF Research Database (Denmark)

    Hilsted, J; Christensen, N J; Larsen, S

    1985-01-01

    Norepinephrine (NE) kinetics (plasma appearance rate, clearance, and forearm extraction) were measured during insulin-induced hypoglycemia in six healthy subjects. NE clearance did not change during hypoglycemia, indicating that the increase in plasma NE during hypoglycemia is due to an increased...

  5. Subcellular localization of the antidepressant-sensitive norepinephrine transporter

    Directory of Open Access Journals (Sweden)

    Winder Danny G

    2009-06-01

    Full Text Available Abstract Background Reuptake of synaptic norepinephrine (NE via the antidepressant-sensitive NE transporter (NET supports efficient noradrenergic signaling and presynaptic NE homeostasis. Limited, and somewhat contradictory, information currently describes the axonal transport and localization of NET in neurons. Results We elucidate NET localization in brain and superior cervical ganglion (SCG neurons, aided by a new NET monoclonal antibody, subcellular immunoisolation techniques and quantitative immunofluorescence approaches. We present evidence that axonal NET extensively colocalizes with syntaxin 1A, and to a limited degree with SCAMP2 and synaptophysin. Intracellular NET in SCG axons and boutons also quantitatively segregates from the vesicular monoamine transporter 2 (VMAT2, findings corroborated by organelle isolation studies. At the surface of SCG boutons, NET resides in both lipid raft and non-lipid raft subdomains and colocalizes with syntaxin 1A. Conclusion Our findings support the hypothesis that SCG NET is segregated prior to transport from the cell body from proteins comprising large dense core vesicles. Once localized to presynaptic boutons, NET does not recycle via VMAT2-positive, small dense core vesicles. Finally, once NET reaches presynaptic plasma membranes, the transporter localizes to syntaxin 1A-rich plasma membrane domains, with a portion found in cholera toxin-demarcated lipid rafts. Our findings indicate that activity-dependent insertion of NET into the SCG plasma membrane derives from vesicles distinct from those that deliver NE. Moreover, NET is localized in presynaptic membranes in a manner that can take advantage of regulatory processes targeting lipid raft subdomains.

  6. Dopamine D1/D5, but not D2/D3, receptor dependency of synaptic plasticity at hippocampal mossy fiber synapses that is enabled by patterned afferent stimulation, or spatial learning

    Directory of Open Access Journals (Sweden)

    Hardy Hagena

    2016-09-01

    Full Text Available Although the mossy fiber (MF synapses of the hippocampal CA3 region display quite distinct properties in terms of the molecular mechanisms that underlie synaptic plasticity, they nonetheless exhibit persistent (>24h synaptic plasticity that is akin to that observed at the Schaffer collateral (SCH-CA1 and perforant path (PP-dentate gyrus (DG synapses of freely behaving rats. In addition, they also respond to novel spatial learning with very enduring forms of long-term potentiation (LTP and long-term depression (LTD. These latter forms of synaptic plasticity are directly related to the learning behavior: novel exploration of generalized changes in space facilitates the expression of LTP at MF-CA3 synapses, whereas exploration of novel configurations of large environmental features facilitates the expression of LTD. In the absence of spatial novelty, synaptic plasticity is not expressed. Motivation is a potent determinant of whether learning about spatial experience effectively occurs and the neuromodulator dopamine plays a key role in motivation-based learning. Prior research on the regulation by dopamine receptors of long-term synaptic plasticity in CA1 and dentate gyrus synapses in vivo suggests that whereas D2/D3 receptors may modulate a general predisposition toward expressing plasticity, D1/D5 receptors may directly regulate the direction of change in synaptic strength that occurs during learning. Although the CA3 region is believed to play a pivotal role in many forms of learning, the role of these receptors in persistent (>24h forms of synaptic plasticity at MF-CA3 synapses is unknown. Here, we report that whereas pharmacological antagonism of D2/D3 receptors had no impact on LTP or LTD, antagonism of D1/D5 receptors significantly impaired LTP and LTD that were induced by solely by means of patterned afferent stimulation, or LTP/LTD that are typically enhanced by the conjunction of afferent stimulation and novel spatial learning. These data

  7. A single amino acid difference between the intracellular domains of amyloid precursor protein and amyloid-like precursor protein 2 enables induction of synaptic depression and block of long-term potentiation.

    Science.gov (United States)

    Trillaud-Doppia, Emilie; Paradis-Isler, Nicolas; Boehm, Jannic

    2016-07-01

    Alzheimer disease (AD) is initially characterized as a disease of the synapse that affects synaptic transmission and synaptic plasticity. While amyloid-beta and tau have been traditionally implicated in causing AD, recent studies suggest that other factors, such as the intracellular domain of the amyloid-precursor protein (APP-ICD), can also play a role in the development of AD. Here, we show that the expression of APP-ICD induces synaptic depression, while the intracellular domain of its homolog amyloid-like precursor protein 2 (APLP2-ICD) does not. We are able to show that this effect by APP-ICD is due to a single alanine vs. proline difference between APP-ICD and APLP2-ICD. The alanine in APP-ICD and the proline in APLP2-ICD lie directly behind a conserved caspase cleavage site. Inhibition of caspase cleavage of APP-ICD prevents the induction of synaptic depression. Finally, we show that the expression of APP-ICD increases and facilitates long-term depression and blocks induction of long-term potentiation. The block in long-term potentiation can be overcome by mutating the aforementioned alanine in APP-ICD to the proline of APLP2. Based on our results, we propose the emergence of a new APP critical domain for the regulation of synaptic plasticity and in consequence for the development of AD. Copyright © 2016 Elsevier Inc. All rights reserved.

  8. The Design, Synthesis and Structure-Activity Relationship of Mixed Serotonin, Norepinephrine and Dopamine Uptake Inhibitors

    Science.gov (United States)

    Chen, Zhengming; Yang, Ji; Skolnick, Phil

    The evolution of antidepressants over the past four decades has involved the replacement of drugs with a multiplicity of effects (e.g., TCAs) by those with selective actions (i.e., SSRIs). This strategy was employed to reduce the adverse effects of TCAs, largely by eliminating interactions with certain neurotransmitters or receptors. Although these more selective compounds may be better tolerated by patients, selective drugs, specifically SSRIs, are not superior to older drugs in treating depressed patients as measured by response and remission rates. It may be an advantage to increase synaptic levels of both serotonin and norepinephrine, as in the case of dual uptake inhibitors like duloxetine and venlafaxine. An important recent development has been the emergence of the triple-uptake inhibitors (TUIs/SNDRIs), which inhibit the uptake of the three neurotransmitters most closely linked to depression: serotonin, norepinephrine, and dopamine. Preclinical studies and clinical trials indicate that a drug inhibiting the reuptake of all three of these neurotransmitters could produce more rapid onset of action and greater efficacy than traditional antidepressants. This review will detail the medicinal chemistry involved in the design, synthesis and discovery of mixed serotonin, norepinephrine and dopamine transporter uptake inhibitors.

  9. Methamphetamine reduces LTP and increases baseline synaptic transmission in the CA1 region of mouse hippocampus.

    Directory of Open Access Journals (Sweden)

    Jarod Swant

    2010-06-01

    Full Text Available Methamphetamine (METH is an addictive psychostimulant whose societal impact is on the rise. Emerging evidence suggests that psychostimulants alter synaptic plasticity in the brain--which may partly account for their adverse effects. While it is known that METH increases the extracellular concentration of monoamines dopamine, serotonin, and norepinephrine, it is not clear how METH alters glutamatergic transmission. Within this context, the aim of the present study was to investigate the effects of acute and systemic METH on basal synaptic transmission and long-term potentiation (LTP; an activity-induced increase in synaptic efficacy in CA1 sub-field in the hippocampus. Both the acute ex vivo application of METH to hippocampal slices and systemic administration of METH decreased LTP. Interestingly, the acute ex vivo application of METH at a concentration of 30 or 60 microM increased baseline synaptic transmission as well as decreased LTP. Pretreatment with eticlopride (D2-like receptor antagonist did not alter the effects of METH on synaptic transmission or LTP. In contrast, pretreatment with D1/D5 dopamine receptor antagonist SCH23390 or 5-HT1A receptor antagonist NAN-190 abrogated the effect of METH on synaptic transmission. Furthermore, METH did not increase baseline synaptic transmission in D1 dopamine receptor haploinsufficient mice. Our findings suggest that METH affects excitatory synaptic transmission via activation of dopamine and serotonin receptor systems in the hippocampus. This modulation may contribute to synaptic maladaption induced by METH addiction and/or METH-mediated cognitive dysfunction.

  10. Interaction of antidepressants with the serotonin and norepinephrine transporters

    DEFF Research Database (Denmark)

    Sørensen, Lena; Andersen, Jacob; Thomsen, Mette

    2012-01-01

    The serotonin transporter (SERT) and the norepinephrine transporter (NET) are sodium-dependent neurotransmitter transporters responsible for reuptake of released serotonin and norepinephrine, respectively, into nerve terminals in the brain. A wide range of inhibitors of SERT and NET are used...

  11. Synaptic Plasticity and Nociception

    Institute of Scientific and Technical Information of China (English)

    ChenJianguo

    2004-01-01

    Synaptic plasticity is one of the fields that progresses rapidly and has a lot of success in neuroscience. The two major types of synaptie plasticity: long-term potentiation ( LTP and long-term depression (LTD are thought to be the cellular mochanisms of learning and memory. Recently, accumulating evidence suggests that, besides serving as a cellular model for learning and memory, the synaptic plasticity involves in other physiological or pathophysiological processes, such as the perception of pain and the regulation of cardiovascular system. This minireview will focus on the relationship between synaptic plasticity and nociception.

  12. Banach Synaptic Algebras

    Science.gov (United States)

    Foulis, David J.; Pulmannov, Sylvia

    2018-04-01

    Using a representation theorem of Erik Alfsen, Frederic Schultz, and Erling Størmer for special JB-algebras, we prove that a synaptic algebra is norm complete (i.e., Banach) if and only if it is isomorphic to the self-adjoint part of a Rickart C∗-algebra. Also, we give conditions on a Banach synaptic algebra that are equivalent to the condition that it is isomorphic to the self-adjoint part of an AW∗-algebra. Moreover, we study some relationships between synaptic algebras and so-called generalized Hermitian algebras.

  13. Memory-enhancing corticosterone treatment increases amygdala norepinephrine and Arc protein expression in hippocampal synaptic fractions

    NARCIS (Netherlands)

    McReynolds, Jayme R.; Donowho, Kyle; Abdi, Amin; McGaugh, James L.; Roozendaal, Benno; McIntyre, Christa K.

    Considerable evidence indicates that glucocorticoid hormones enhance the consolidation of memory for emotionally arousing events through interactions with the noradrenergic system of the basolateral complex of the amygdala (BLA). We previously reported that intra-BLA administration of a

  14. Synaptic Correlates of Working Memory Capacity.

    Science.gov (United States)

    Mi, Yuanyuan; Katkov, Mikhail; Tsodyks, Misha

    2017-01-18

    Psychological studies indicate that human ability to keep information in readily accessible working memory is limited to four items for most people. This extremely low capacity severely limits execution of many cognitive tasks, but its neuronal underpinnings remain unclear. Here we show that in the framework of synaptic theory of working memory, capacity can be analytically estimated to scale with characteristic time of short-term synaptic depression relative to synaptic current time constant. The number of items in working memory can be regulated by external excitation, enabling the system to be tuned to the desired load and to clear the working memory of currently held items to make room for new ones. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. The Corticohippocampal Circuit, Synaptic Plasticity, and Memory

    Science.gov (United States)

    Basu, Jayeeta; Siegelbaum, Steven A.

    2015-01-01

    Synaptic plasticity serves as a cellular substrate for information storage in the central nervous system. The entorhinal cortex (EC) and hippocampus are interconnected brain areas supporting basic cognitive functions important for the formation and retrieval of declarative memories. Here, we discuss how information flow in the EC–hippocampal loop is organized through circuit design. We highlight recently identified corticohippocampal and intrahippocampal connections and how these long-range and local microcircuits contribute to learning. This review also describes various forms of activity-dependent mechanisms that change the strength of corticohippocampal synaptic transmission. A key point to emerge from these studies is that patterned activity and interaction of coincident inputs gives rise to associational plasticity and long-term regulation of information flow. Finally, we offer insights about how learning-related synaptic plasticity within the corticohippocampal circuit during sensory experiences may enable adaptive behaviors for encoding spatial, episodic, social, and contextual memories. PMID:26525152

  16. Relationships of Whole Blood Serotonin and Plasma Norepinephrine within Families.

    Science.gov (United States)

    Leventhal, Bennett L.; And Others

    1990-01-01

    This study of 47 families of autistic probands found that whole blood serotonin was positively correlated between autistic children and their mothers, fathers, and siblings, but plasma norepinephrine levels were not. (Author/JDD)

  17. Expression of the capacity to release [3H]norepinephrine by neural crest cultures

    International Nuclear Information System (INIS)

    Maxwell, G.D.; Sietz, P.D.

    1983-01-01

    Cultures of trunk neural crest cells from quail embryos were tested for their ability to release [ 3 H]norepinephrine [( 3 H]NE) in response to depolarization. After 7 days in vitro, exposure of the cultures to either the alkaloid veratridine or 40 mM K+ results in the evoked release of [ 3 H]NE. The release evoked by veratridine is blocked in the presence of tetrodotoxin. The release evoked by increased K+ is blocked by the calcium antagonist cobalt. Release in response to the nicotinic cholinergic agonist 1,1-dimethyl-4-phenylpiperazine was also observed. The amount of evoked release is highly correlated with the number of histochemically demonstrable catecholamine-containing cells in a given culture. Autoradiography reveals that the radioactivity taken up by these cultures is located in a subpopulation of cells whose morphology resembles that of the histochemically detectable catecholamine-containing cell population. Whereas capacity for the release of [ 3 H] NE is readily detectable after 7 days in vitro, it is detectable only with difficulty after 4 days in vitro. There is a greater than 6-fold increase in uptake capacity over the period of 4 to 7 days in vitro. These results demonstrate that neural crest cultures grown without their normal synaptic inputs or targets can exhibit the capacity for stimulus secretion coupling characteristic of synaptic neurotransmitter release

  18. Continuous infusion of tracer norepinephrine may miscalculate unidirectional nerve uptake of norepinephrine in humans

    DEFF Research Database (Denmark)

    Henriksen, Jens Henrik Sahl; Christensen, N J; Ring-Larsen, H

    1989-01-01

    In order to evaluate uptake kinetics of norepinephrine (NE) in different tissues, a catheterization study was performed in control subjects (n = 6) and patients with enhanced sympathetic nervous activity (cirrhosis, n = 12) during constant intravenous infusion of L[3H]norepinephrine ([3H]NE) for 75...... minutes. In spite of a higher NE spillover from kidneys in patients compared with controls (82 vs. 49 ng/min, p less than 0.01), renal extraction ratios of [3H]NE were similar in the two groups (0.33 vs. 0.32, NS), and no significant change was observed during the time of infusion. In contrast, liver......-intestine extraction ratios of [3H]NE decreased significantly and equally with infusion time in patients (from 0.57 to 0.44, p less than 0.01) and controls (from 0.59 to 0.46, p less than 0.01). This was observed despite the fact that spillover of NE from this vascular bed was observed only in patients with cirrhosis...

  19. Norepinephrine release in arteries of spontaneously hypertensive rats

    International Nuclear Information System (INIS)

    Zsoter, T.T.; Wolchinsky, C.; Lawrin, M.; Sirko, S.

    1982-01-01

    The role of the sympathetic nervous system in arterial hypertension cannot be properly evaluated until it is known about the activity in the vessels themselves. In this study researchers investigated the effect of transmural stimulation on the tail artery - labelled in vitro with 3 H-norepinephrine - of 7-9 week old spontaneously hypertensive rats (SHR) and Wistar Kyoto controls (WKR). Electrical stimulation using two frequencies (2 and 10 Hz) resulted in significantly more 3 H overflow in vessels from SHR than from WKR. With 10 Hz stimulation the fractional release was also greater. Column chromatographic analysis of 3 H overflow revealed that transmural stimulation in arteries of SHR enhanced mainly the release of norepinephrine and not of its metabolites. Significantly, an increased release of 3 H-norepinephrine on stimulation was observed in SHR before the full development of hypertension suggesting that it might be a cause rather than a consequence of high blood pressure

  20. Norepinephrine kinetics and dynamics in septic shock and trauma patients.

    Science.gov (United States)

    Beloeil, H; Mazoit, J-X; Benhamou, D; Duranteau, J

    2005-12-01

    There is considerable variability in the inter-patient response to norepinephrine. Pharmacokinetic studies of dopamine infusion in volunteers and in patients have also shown large variability. The purpose of this study was to define the pharmacokinetics of norepinephrine in septic shock and trauma patients. After Ethical Committee approval and written informed family consent, 12 patients with septic shock and 11 trauma patients requiring norepinephrine infusion were studied. Norepinephrine dose was increased in three successive steps of 0.1 mg kg(-1) min(-1) at 15-min intervals (20% maximum allowed increase in arterial pressure). Arterial blood was sampled before and at 0.5, 13, and 15 min after each infusion rate change and 30 s, 1, 2, 5, 10, and 15 min after return to baseline dosing. Norepinephrine was assayed by HPLC. The pharmacokinetics were modelled using NONMEM (one-compartment model). The effects of group, body weight (BW), gender and SAPS II (Simplified Acute Physiology Score II) [Le Gall JR, Lemeshow S, Saulnier F. A new Simplified Acute Physiology Score (SAPS II) based on a European/North American multicenter study. J Am Med Assoc 1993; 270: 2957-63] patients score on clearance (CL) and volume of distribution (V) were tested. Group, gender, and BW did not influence CL or V. CL was negatively related to SAPS II. CL and T(1/2) varied from 3 litre min(-1) and 2 min, respectively, when SAPS II=20 to 0.9 litre min(-1) and 6.8 min when SAPS II=60. In trauma patients and in septic shock patients, norepinephrine clearance is negatively related to SAPS II.

  1. Spine Calcium Transients Induced by Synaptically-Evoked Action Potentials Can Predict Synapse Location and Establish Synaptic Democracy

    Science.gov (United States)

    Meredith, Rhiannon M.; van Ooyen, Arjen

    2012-01-01

    CA1 pyramidal neurons receive hundreds of synaptic inputs at different distances from the soma. Distance-dependent synaptic scaling enables distal and proximal synapses to influence the somatic membrane equally, a phenomenon called “synaptic democracy”. How this is established is unclear. The backpropagating action potential (BAP) is hypothesised to provide distance-dependent information to synapses, allowing synaptic strengths to scale accordingly. Experimental measurements show that a BAP evoked by current injection at the soma causes calcium currents in the apical shaft whose amplitudes decay with distance from the soma. However, in vivo action potentials are not induced by somatic current injection but by synaptic inputs along the dendrites, which creates a different excitable state of the dendrites. Due to technical limitations, it is not possible to study experimentally whether distance information can also be provided by synaptically-evoked BAPs. Therefore we adapted a realistic morphological and electrophysiological model to measure BAP-induced voltage and calcium signals in spines after Schaffer collateral synapse stimulation. We show that peak calcium concentration is highly correlated with soma-synapse distance under a number of physiologically-realistic suprathreshold stimulation regimes and for a range of dendritic morphologies. Peak calcium levels also predicted the attenuation of the EPSP across the dendritic tree. Furthermore, we show that peak calcium can be used to set up a synaptic democracy in a homeostatic manner, whereby synapses regulate their synaptic strength on the basis of the difference between peak calcium and a uniform target value. We conclude that information derived from synaptically-generated BAPs can indicate synapse location and can subsequently be utilised to implement a synaptic democracy. PMID:22719238

  2. Discovery of a potent, dual serotonin and norepinephrine reuptake inhibitor.

    Science.gov (United States)

    Dreyfus, Nicolas; Myers, Jason K; Badescu, Valentina O; de Frutos, Oscar; de la Puente, Maria Luz; Ding, Chunjin; Filla, Sandra A; Fynboe, Karsten; Gernert, Douglas L; Heinz, Beverly A; Hemrick-Luecke, Susan K; Johnson, Kirk W; Johnson, Michael P; López, Pilar; Love, Patrick L; Martin, Laura J; Masquelin, Thierry; McCoy, Michael J; Mendiola, Javier; Morrow, Denise; Muhlhauser, Mark; Pascual, Gustavo; Perun, Thomas J; Pfeifer, Lance A; Phebus, Lee A; Richards, Simon J; Rincón, Juan Antonio; Seest, Eric P; Shah, Jikesh; Shaojuan, Jia; Simmons, Rosa Maria A; Stephenson, Gregory A; Tromiczak, Eric G; Thompson, Linda K; Walter, Magnus W; Weber, Wayne W; Zarrinmayeh, Hamideh; Thomas, Craig E; Joshi, Elizabeth; Iyengar, Smriti; Johansson, Anette M

    2013-06-13

    The objective of the described research effort was to identify a novel serotonin and norepinephrine reuptake inhibitor (SNRI) with improved norepinephrine transporter activity and acceptable metabolic stability and exhibiting minimal drug-drug interaction. We describe herein the discovery of a series of 3-substituted pyrrolidines, exemplified by compound 1. Compound 1 is a selective SNRI in vitro and in vivo, has favorable ADME properties, and retains inhibitory activity in the formalin model of pain behavior. Compound 1 thus represents a potential new probe to explore utility of SNRIs in central nervous system disorders, including chronic pain conditions.

  3. Improved preclinical cardiovascular therapeutic indices with long-term inhibition of norepinephrine reuptake using reboxetine

    NARCIS (Netherlands)

    Fossa, Anthony A.; Wisialowski, Todd A.; Cremers, Thomas; van der Hart, Marieke; Tseng, Elaine; Deng, Shibing; Rollema, Hans; Wang, Ellen Q.

    2012-01-01

    Norepinephrine reuptake inhibitors (NRIs) acutely increase norepinephrine (NE) levels, but therapeutic antidepressant activity is only observed after weeks of treatment because central NE levels progressively increase during continued drug exposure. Similarly, while NRIs acutely increase blood

  4. Norepinephrine transporter blocker atomoxetine increases salivary alpha amylase

    NARCIS (Netherlands)

    Warren, C.M.; van den Brink, R.L.; Nieuwenhuis, S.; Bosch, J.A.

    It has been suggested that central norepinephrine (NE) activity may be inferred from increases in salivary alpha-amylase (SAA), but data in favor of this proposition are limited. We administered 40mg of atomoxetine, a selective NE transporter blocker that increases central NE levels, to 24 healthy

  5. Arousal, exploration and the locus coeruleus-norepinephrine system

    NARCIS (Netherlands)

    Jepma, Marieke

    2011-01-01

    The studies described in this thesis address a range of topics related to arousal, exploration, temporal attention, and the locus coeruleus-norepinephrine (LC-NE) system. Chapters 2 and 3 report two studies that investigated a recent theory about the role of the LC-NE system in the regulation of the

  6. Radioenzymatic simultaneous determination of epinephrine and norepinephrine in plasma

    International Nuclear Information System (INIS)

    Mueller, T.

    1978-01-01

    The high-pressure liquid chromatography (= HPLC) was used in simultaneous determinations of a few pg epinephrine and norepinephrine. This separation procedure improves the efficiency when compared with the conventional thin-layer chromatographic methods (TLC) and allows routine assays in plasma. (orig.) [de

  7. Regulation of the fear network by mediators of stress: Norepinephrine alters the balance between Cortical and Subcortical afferent excitation of the Lateral Amygdala

    Directory of Open Access Journals (Sweden)

    Luke R Johnson

    2011-05-01

    Full Text Available Pavlovian auditory fear conditioning crucially involves the integration of information about and acoustic conditioned stimulus (CS and an aversive unconditioned stimulus (US in the lateral nucleus of the amygdala (LA. The auditory CS reaches the LA subcortically via a direct connection from the auditory thalamus and also from the auditory association cortex itself. How neural modulators, especially those activated during stress, such as norepinephrine (NE, regulate synaptic transmission and plasticity in this network is poorly understood. Here we show that NE inhibits synaptic transmission in both the subcortical and cortical input pathway but that sensory processing is biased towards the subcortical pathway. In addition binding of NE to β-adrenergic receptors further dissociates sensory processing in the LA. These findings suggest a network mechanism that shifts sensory balance towards the faster but more primitive subcortical input.

  8. MAGUKs: multifaceted synaptic organizers.

    Science.gov (United States)

    Won, Sehoon; Levy, Jon M; Nicoll, Roger A; Roche, Katherine W

    2017-04-01

    The PSD-95 family of proteins, known as MAGUKs, have long been recognized to be central building blocks of the PSD. They are categorized as scaffolding proteins, which link surface-expressed receptors to the intracellular signaling molecules. Although the four members of the PSD-95 family (PSD-95, PSD-93, SAP102, and SAP97) have many shared roles in regulating synaptic function, recent studies have begun to delineate specific binding partners and roles in plasticity. In the current review, we will highlight the conserved and unique roles of these proteins. Published by Elsevier Ltd.

  9. Norepinephrine induces pathway-specific long-lasting potentiation and depression in the hippocampal dentate gyrus.

    Science.gov (United States)

    Dahl, D; Sarvey, J M

    1989-01-01

    The study presented here indicates that norepinephrine (NE) selectively induces long-lasting modifications of synaptically mediated responses in the dentate gyrus of the rat hippocampal slice. A low concentration of NE (1.0 microM; in the presence of 50 microM phentolamine, an alpha-adrenergic antagonist) or a 1.0 microM concentration of the specific beta-adrenergic agonist isoproterenol induced long-lasting pathway-specific alterations of granule cell electrophysiological responses. Excitatory postsynaptic potentials and population spikes evoked by stimulation of the medial perforant pathway (PP) were potentiated for more than 45 min. In contrast, responses to lateral PP stimulation were depressed for the same period. Both potentiation and depression were blocked by the beta-adrenergic antagonist propranolol (1.0 microM). These results indicate that NE can act differentially on projections to the dentate gyrus arising in the entorhinal cortex. Such selective persistent modifications of cortical circuits may be involved in processes in the mammalian brain underlying attention, learning, and memory. PMID:2734319

  10. The Role of L-type Calcium Channels in Olfactory Learning and Its Modulation by Norepinephrine

    Directory of Open Access Journals (Sweden)

    Abhinaba Ghosh

    2017-12-01

    Full Text Available L type calcium channels (LTCCs are prevalent in different systems and hold immense importance for maintaining/performing selective functions. In the nervous system, CaV1.2 and CaV1.3 are emerging as critical modulators of neuronal functions. Although the general role of these calcium channels in modulating synaptic plasticity and memory has been explored, their role in olfactory learning is not well understood. In this review article we first discuss the role of LTCCs in olfactory learning especially focusing on early odor preference learning in neonate rodents, presenting evidence that while NMDARs initiate stimulus-specific learning, LTCCs promote protein-synthesis dependent long-term memory (LTM. Norepinephrine (NE release from the locus coeruleus (LC is essential for early olfactory learning, thus noradrenergic modulation of LTCC function and its implication in olfactory learning is discussed here. We then address the differential roles of LTCCs in adult learning and learning in aged animals.

  11. Recurrent hypoglycemia increases anxiety and amygdala norepinephrine release during subsequent hypoglycemia

    Directory of Open Access Journals (Sweden)

    Ewan eMcNay

    2015-11-01

    Full Text Available Recurrent hypoglycemia (RH is a common and debilitating side effect of therapy in patients with both type 1 and, increasingly, type 2 diabetes. Previous studies in rats have shown marked effects of RH on subsequent hippocampal behavioral, metabolic, and synaptic processes. In addition to impaired memory, patients experiencing RH report alterations in cognitive processes that include mood and anxiety, suggesting that RH may also affect amygdala function. We tested the impact of RH on amygdala function using an elevated plus-maze test of anxiety together with in vivo amygdala microdialysis for norepinephrine (NEp, a widely used marker of basolateral amygdala cognitive processes. In contrast to findings in the hippocampus and pre-frontal cortex, neither RH nor acute hypoglycemia alone significantly affected plus-maze performance or NEp release. However, animals tested when hypoglycemic who had previously experienced RH had elevated amygdala NEp during plus-maze testing, accompanied by increased anxiety (i.e. less time spent in the open arms of the plus-maze. The results show that RH has widespread effects on subsequent brain function, which vary by neural system.

  12. Spatiotemporal norepinephrine mapping using a high-density CMOS microelectrode array.

    Science.gov (United States)

    Wydallis, John B; Feeny, Rachel M; Wilson, William; Kern, Tucker; Chen, Tom; Tobet, Stuart; Reynolds, Melissa M; Henry, Charles S

    2015-10-21

    A high-density amperometric electrode array containing 8192 individually addressable platinum working electrodes with an integrated potentiostat fabricated using Complementary Metal Oxide Semiconductor (CMOS) processes is reported. The array was designed to enable electrochemical imaging of chemical gradients with high spatiotemporal resolution. Electrodes are arranged over a 2 mm × 2 mm surface area into 64 subarrays consisting of 128 individual Pt working electrodes as well as Pt pseudo-reference and auxiliary electrodes. Amperometric measurements of norepinephrine in tissue culture media were used to demonstrate the ability of the array to measure concentration gradients in complex media. Poly(dimethylsiloxane) microfluidics were incorporated to control the chemical concentrations in time and space, and the electrochemical response at each electrode was monitored to generate electrochemical heat maps, demonstrating the array's imaging capabilities. A temporal resolution of 10 ms can be achieved by simultaneously monitoring a single subarray of 128 electrodes. The entire 2 mm × 2 mm area can be electrochemically imaged in 64 seconds by cycling through all subarrays at a rate of 1 Hz per subarray. Monitoring diffusional transport of norepinephrine is used to demonstrate the spatiotemporal resolution capabilities of the system.

  13. Synaptic electronics: materials, devices and applications.

    Science.gov (United States)

    Kuzum, Duygu; Yu, Shimeng; Wong, H-S Philip

    2013-09-27

    In this paper, the recent progress of synaptic electronics is reviewed. The basics of biological synaptic plasticity and learning are described. The material properties and electrical switching characteristics of a variety of synaptic devices are discussed, with a focus on the use of synaptic devices for neuromorphic or brain-inspired computing. Performance metrics desirable for large-scale implementations of synaptic devices are illustrated. A review of recent work on targeted computing applications with synaptic devices is presented.

  14. Synaptic electronics: materials, devices and applications

    International Nuclear Information System (INIS)

    Kuzum, Duygu; Yu, Shimeng; Philip Wong, H-S

    2013-01-01

    In this paper, the recent progress of synaptic electronics is reviewed. The basics of biological synaptic plasticity and learning are described. The material properties and electrical switching characteristics of a variety of synaptic devices are discussed, with a focus on the use of synaptic devices for neuromorphic or brain-inspired computing. Performance metrics desirable for large-scale implementations of synaptic devices are illustrated. A review of recent work on targeted computing applications with synaptic devices is presented. (topical review)

  15. Norepinephrine as a Potential Aggravator of Symptomatic Cerebral Vasospasm: Two Cases and Argument for Milrinone Therapy

    Directory of Open Access Journals (Sweden)

    F. A. Zeiler

    2014-01-01

    Full Text Available Background. During hypertensive therapy for post-subarachnoid hemorrhage (SAH symptomatic vasospasm, norepinephrine is commonly used to reach target blood pressures. Concerns over aggravation of vasospasm with norepinephrine exist. Objective. To describe norepinephrine temporally related deterioration in neurological examination of two post-SAH patients in vasospasm. Methods. We retrospectively reviewed two charts of patients with delayed cerebral ischemia (DCI post-SAH who deteriorated with norepinephrine infusions. Results. We identified two patients with DCI post-SAH who deteriorated during hypertensive therapy with norepinephrine. The first, a 43-year-old male presented to hospital with DCI, failed MABP directed therapy with rapid deterioration in exam with high dose norepinephrine and MABP of 140–150 mm Hg. His exam improved on continuous milrinone and discontinuation of norepinephrine. The second, a 39-year-old female who developed DCI on postbleed day 8 responded to milrinone therapy upfront. During further deterioration and after angioplasty, norepinephrine was utilized to drive MABP to 130–140 mm Hg. Progressive deterioration in examination occurred after angioplasty as norepinephrine doses escalated. After discontinuation of norepinephrine and continuation of milrinone, function dramatically returned but not to baseline. Conclusions. The potential exists for worsening of DCI post-SAH with hypertensive therapy directed by norepinephrine. A potential role exists for vasodilation and inotropic directed therapy with milrinone in the setting of DCI post-SAH.

  16. Gold Nanoparticles-Based Barcode Analysis for Detection of Norepinephrine.

    Science.gov (United States)

    An, Jeung Hee; Lee, Kwon-Jai; Choi, Jeong-Woo

    2016-02-01

    Nanotechnology-based bio-barcode amplification analysis offers an innovative approach for detecting neurotransmitters. We evaluated the efficacy of this method for detecting norepinephrine in normal and oxidative-stress damaged dopaminergic cells. Our approach use a combination of DNA barcodes and bead-based immunoassays for detecting neurotransmitters with surface-enhanced Raman spectroscopy (SERS), and provides polymerase chain reaction (PCR)-like sensitivity. This method relies on magnetic Dynabeads containing antibodies and nanoparticles that are loaded both with DNA barcords and with antibodies that can sandwich the target protein captured by the Dynabead-bound antibodies. The aggregate sandwich structures are magnetically separated from the solution and treated to remove the conjugated barcode DNA. The DNA barcodes are then identified by SERS and PCR analysis. The concentration of norepinephrine in dopaminergic cells can be readily detected using the bio-barcode assay, which is a rapid, high-throughput screening tool for detecting neurotransmitters.

  17. Inhibition of the norepinephrine transporter by χ-conotoxin dendrimers.

    Science.gov (United States)

    Wan, Jingjing; Brust, Andreas; Bhola, Rebecca F; Jha, Prerna; Mobli, Mehdi; Lewis, Richard J; Christie, Macdonald J; Alewood, Paul F

    2016-05-01

    Peptide dendrimers are a novel class of macromolecules of emerging interest with the potential of delayed renal clearance due to their molecular size and enhanced activity due to the multivalency effect. In this work, an active analogue of the disulfide-rich χ-conotoxin χ-MrIA (χ-MrIA), a norepinephrine reuptake (norepinephrine transporter) inhibitor, was grafted onto a polylysine dendron. Dendron decoration was achieved by employing copper-catalyzed alkyne-azide cycloaddition with azido-PEG chain-modified χ-MrIA analogues, leading to homogenous 4-mer and 8-mer χ-MrIA dendrimers with molecular weights ranging from 8 to 22 kDa. These dendrimers were investigated for their impact on peptide secondary structure, in vitro functional activity, and potential anti-allodynia in vivo. NMR studies showed that the χ-MrIA tertiary structure was maintained in the χ-MrIA dendrimers. In a functional norepinephrine transporter reuptake assay, χ-MrIA dendrimers showed slightly increased potency relative to the azido-PEGylated χ-MrIA analogues with similar potency to the parent peptide. In contrast to χ-MrIA, no anti-allodynic action was observed when the χ-MrIA dendrimers were administered intrathecally in a rat model of neuropathic pain, suggesting that the larger dendrimer structures are unable to diffuse through the spinal column tissue and reach the norepinephrine transporter. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd.

  18. Influence of norepinephrine transporter inhibition on hemodynamic response to hypergravitation

    OpenAIRE

    Strempel, Sebastian

    2011-01-01

    Background: Sympathetically-mediated tachycardia and vasoconstriction maintain blood pressure during hypergravitational stress, thereby preventing gravitation-induced loss of consciousness (g-LOC). Norepinephrine transporter (NET) inhibition prevents neurally-mediated (pre)syncope during gravitational stress imposed by head-up tilt testing. Thus, it seems reasonable that NET inhibition could increase tolerance to hypergravitational stress. Methods. We performed a double-blind, randomized...

  19. Control of synaptic plasticity in deep cortical networks

    NARCIS (Netherlands)

    Roelfsema, Pieter R.; Holtmaat, Anthony

    2018-01-01

    Humans and many other animals have an enormous capacity to learn about sensory stimuli and to master new skills. However, many of the mechanisms that enable us to learn remain to be understood. One of the greatest challenges of systems neuroscience is to explain how synaptic connections change to

  20. Mechanisms of immune regulation by norepinephrine and cholera toxin

    International Nuclear Information System (INIS)

    Campbell, K.S.

    1988-01-01

    Norepinephrine has previously been demonstrated by this laboratory to potentiate the in vitro T-dependent antibody response through the stimulation of β-adrenergic receptors. The role of β-adrenergic receptor subtypes in norepinephrine-induced potentiation of the antibody responses was examined with selective β-adrenergic antagonists. The antagonists were metoprolol (β 1 -selective), ICI 118-551 (β 2 -selective), and propranolol (β-non-selective). Both propranolol and ICI 118-551 blocked norepinephrine-induced potentiation of the antibody response, but metoprolol was ineffective. Receptor binding competition of antagonists with the radioligant, [ 3 H]CGP-12177 was examined and results were analyzed with the computer program, LIGAND. Competition by ICI 118-551 identified 75% β 2 - and 25% β 1 -adrenergic receptors on splenic mononuclear cells. Enriched T lymphocytes exhibited 75% β 2 -adrenergic receptors, while enriched B lymphocytes contained 90% β 2 -adrenergic receptors as identified by ICI 118-551. Greater than twice as many total receptors were identified on B lymphocytes than T lymphocytes. A T cell lymphoma contained about 60% β 2 -receptors, while 100% were β 2 receptors on a B cell lymphoma, as assessed by ICI 118-551. Results support a heterogeneous β-adrenergic receptor population on T lymphocytes and a more homogeneous β 2 -population on B lymphocytes

  1. Mechanisms of immune regulation by norepinephrine and cholera toxin

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, K.S.

    1988-01-01

    Norepinephrine has previously been demonstrated by this laboratory to potentiate the in vitro T-dependent antibody response through the stimulation of {beta}-adrenergic receptors. The role of {beta}-adrenergic receptor subtypes in norepinephrine-induced potentiation of the antibody responses was examined with selective {beta}-adrenergic antagonists. The antagonists were metoprolol ({beta}{sub 1}-selective), ICI 118-551 ({beta}{sub 2}-selective), and propranolol ({beta}-non-selective). Both propranolol and ICI 118-551 blocked norepinephrine-induced potentiation of the antibody response, but metoprolol was ineffective. Receptor binding competition of antagonists with the radioligant, ({sup 3}H)CGP-12177 was examined and results were analyzed with the computer program, LIGAND. Competition by ICI 118-551 identified 75% {beta}{sub 2}- and 25% {beta}{sub 1}-adrenergic receptors on splenic mononuclear cells. Enriched T lymphocytes exhibited 75% {beta}{sub 2}-adrenergic receptors, while enriched B lymphocytes contained 90% {beta}{sub 2}-adrenergic receptors as identified by ICI 118-551. Greater than twice as many total receptors were identified on B lymphocytes than T lymphocytes. A T cell lymphoma contained about 60% {beta}{sub 2}-receptors, while 100% were {beta}{sub 2} receptors on a B cell lymphoma, as assessed by ICI 118-551. Results support a heterogeneous {beta}-adrenergic receptor population on T lymphocytes and a more homogeneous {beta}{sub 2}-population on B lymphocytes.

  2. Isolation of Synaptosomes, Synaptic Plasma Membranes, and Synaptic Junctional Complexes.

    Science.gov (United States)

    Michaelis, Mary L; Jiang, Lei; Michaelis, Elias K

    2017-01-01

    Isolation of synaptic nerve terminals or synaptosomes provides an opportunity to study the process of neurotransmission at many levels and with a variety of approaches. For example, structural features of the synaptic terminals and the organelles within them, such as synaptic vesicles and mitochondria, have been elucidated with electron microscopy. The postsynaptic membranes are joined to the presynaptic "active zone" of transmitter release through cell adhesion molecules and remain attached throughout the isolation of synaptosomes. These "post synaptic densities" or "PSDs" contain the receptors for the transmitters released from the nerve terminals and can easily be seen with electron microscopy. Biochemical and cell biological studies with synaptosomes have revealed which proteins and lipids are most actively involved in synaptic release of neurotransmitters. The functional properties of the nerve terminals, such as responses to depolarization and the uptake or release of signaling molecules, have also been characterized through the use of fluorescent dyes, tagged transmitters, and transporter substrates. In addition, isolated synaptosomes can serve as the starting material for the isolation of relatively pure synaptic plasma membranes (SPMs) that are devoid of organelles from the internal environment of the nerve terminal, such as mitochondria and synaptic vesicles. The isolated SPMs can reseal and form vesicular structures in which transport of ions such as sodium and calcium, as well as solutes such as neurotransmitters can be studied. The PSDs also remain associated with the presynaptic membranes during isolation of SPM fractions, making it possible to isolate the synaptic junctional complexes (SJCs) devoid of the rest of the plasma membranes of the nerve terminals and postsynaptic membrane components. Isolated SJCs can be used to identify the proteins that constitute this highly specialized region of neurons. In this chapter, we describe the steps involved

  3. Exclusion of close linkage between the synaptic vesicular monoamine transporter locus and schizophrenia spectrum disorders

    Energy Technology Data Exchange (ETDEWEB)

    Persico, A.M.; Uhl, G.R. [Johns Hopkins Univ. School of Medicine, Baltimore, MD (United States); Wang, Zhe Wu [Universitario Campus Bio-Medico, Rome (Italy)] [and others

    1995-12-18

    The principal brain synaptic vesicular monoamine transporter (VMAT2) is responsible for the reuptake of serotonin, dopamine, norepinephrine, epinephrine, and histamine from the cytoplasm into synaptic vesicles, thus contributing to determination of the size of releasable neurotransmitter vesicular pools. Potential involvement of VMAT2 gene variants in the etiology of schizophrenia and related disorders was tested using polymorphic VMAT2 gene markers in 156 subjects from 16 multiplex pedigrees with schizophrenia, schizophreniform, schizoaffective, and schizotypal disorders and mood incongruent psychotic depression. Assuming genetic homogeneity, complete ({theta} = 0.0) linkage to the schizophrenia spectrum was excluded under both dominant and recessive models. Allelic variants at the VMAT2 locus do not appear to provide major genetic contributions to the etiology of schizophrenia spectrum disorders in these pedigrees. 16 refs.

  4. Secreted factors as synaptic organizers.

    Science.gov (United States)

    Johnson-Venkatesh, Erin M; Umemori, Hisashi

    2010-07-01

    A critical step in synaptic development is the differentiation of presynaptic and postsynaptic compartments. This complex process is regulated by a variety of secreted factors that serve as synaptic organizers. Specifically, fibroblast growth factors, Wnts, neurotrophic factors and various other intercellular signaling molecules are proposed to regulate presynaptic and/or postsynaptic differentiation. Many of these factors appear to function at both the neuromuscular junction and in the central nervous system, although the specific function of the molecules differs between the two. Here we review secreted molecules that organize the synaptic compartments and discuss how these molecules shape synaptic development, focusing on mammalian in vivo systems. Their critical role in shaping a functional neural circuit is underscored by their possible link to a wide range of neurological and psychiatric disorders both in animal models and by mutations identified in human patients. © The Authors (2010). Journal Compilation © Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

  5. Synaptic consolidation across multiple timescales

    Directory of Open Access Journals (Sweden)

    Lorric Ziegler

    2014-03-01

    Full Text Available The brain is bombarded with a continuous stream of sensory events, but retains only a small subset in memory. The selectivity of memory formation prevents our memory from being overloaded with irrelevant items that would rapidly bring the brain to its storage limit; moreover, selectivity also prevents overwriting previously formed memories with new ones. Memory formation in the hippocampus, as well as in other brain regions, is thought to be linked to changes in the synaptic connections between neurons. In this view, sensory events imprint traces at the level of synapses that reflect potential memory items. The question of memory selectivity can therefore be reformulated as follows: what are the reasons and conditions that some synaptic traces fade away whereas others are consolidated and persist? Experimentally, changes in synaptic strength induced by 'Hebbian' protocols fade away over a few hours (early long-term potentiation or e-LTP, unless these changes are consolidated. The experiments and conceptual theory of synaptic tagging and capture (STC provide a mechanistic explanation for the processes involved in consolidation. This theory suggests that the initial trace of synaptic plasticity sets a tag at the synapse, which then serves as a marker for potential consolidation of the changes in synaptic efficacy. The actual consolidation processes, transforming e-LTP into late LTP (l-LTP, require the capture of plasticity-related proteins (PRP. We translate the above conceptual model into a compact computational model that accounts for a wealth of in vitro data including experiments on cross-tagging, tag-resetting and depotentiation. A central ingredient is that synaptic traces are described with several variables that evolve on different time scales. Consolidation requires the transmission of information from a 'fast' synaptic trace to a 'slow' one through a 'write' process, including the formation of tags and the production of PRP for the

  6. Integrated neuron circuit for implementing neuromorphic system with synaptic device

    Science.gov (United States)

    Lee, Jeong-Jun; Park, Jungjin; Kwon, Min-Woo; Hwang, Sungmin; Kim, Hyungjin; Park, Byung-Gook

    2018-02-01

    In this paper, we propose and fabricate Integrate & Fire neuron circuit for implementing neuromorphic system. Overall operation of the circuit is verified by measuring discrete devices and the output characteristics of the circuit. Since the neuron circuit shows asymmetric output characteristic that can drive synaptic device with Spike-Timing-Dependent-Plasticity (STDP) characteristic, the autonomous weight update process is also verified by connecting the synaptic device and the neuron circuit. The timing difference of the pre-neuron and the post-neuron induce autonomous weight change of the synaptic device. Unlike 2-terminal devices, which is frequently used to implement neuromorphic system, proposed scheme of the system enables autonomous weight update and simple configuration by using 4-terminal synapse device and appropriate neuron circuit. Weight update process in the multi-layer neuron-synapse connection ensures implementation of the hardware-based artificial intelligence, based on Spiking-Neural- Network (SNN).

  7. Norepinephrine-evoked pain in fibromyalgia. A randomized pilot study [ISRCTN70707830

    Directory of Open Access Journals (Sweden)

    Casanova Jose-Miguel

    2002-01-01

    Full Text Available Abstract Background Fibromyalgia syndrome displays sympathetically maintained pain features such as frequent post-traumatic onset and stimuli-independent pain accompanied by allodynia and paresthesias. Heart rate variability studies showed that fibromyalgia patients have changes consistent with ongoing sympathetic hyperactivity. Norepinephrine-evoked pain test is used to assess sympathetically maintained pain syndromes. Our objective was to define if fibromyalgia patients have norepinephrine-evoked pain. Methods Prospective double blind controlled study. Participants: Twenty FM patients, and two age/sex matched control groups; 20 rheumatoid arthritis patients and 20 healthy controls. Ten micrograms of norepinephrine diluted in 0.1 ml of saline solution were injected in a forearm. The contrasting substance, 0.1 ml of saline solution alone, was injected in the opposite forearm. Maximum local pain elicited during the 5 minutes post-injection was graded on a visual analog scale (VAS. Norepinephrine-evoked pain was diagnosed when norepinephrine injection induced greater pain than placebo injection. Intensity of norepinephrine-evoked pain was calculated as the difference between norepinephrine minus placebo-induced VAS scores. Results Norepinephrine-evoked pain was seen in 80 % of FM patients (95% confidence intervals 56.3 – 94.3%, in 30 % of rheumatoid arthritis patients and in 30 % of healthy controls (95% confidence intervals 11.9 – 54.3 (p Conclusions Fibromyalgia patients have norepinephrine-evoked pain. This finding supports the hypothesis that fibromyalgia may be a sympathetically maintained pain syndrome.

  8. Norepinephrine ignites local hotspots of neuronal excitation: How arousal amplifies selectivity in perception and memory.

    Science.gov (United States)

    Mather, Mara; Clewett, David; Sakaki, Michiko; Harley, Carolyn W

    2016-01-01

    Emotional arousal enhances perception and memory of high-priority information but impairs processing of other information. Here, we propose that, under arousal, local glutamate levels signal the current strength of a representation and interact with norepinephrine (NE) to enhance high priority representations and out-compete or suppress lower priority representations. In our "glutamate amplifies noradrenergic effects" (GANE) model, high glutamate at the site of prioritized representations increases local NE release from the locus coeruleus (LC) to generate "NE hotspots." At these NE hotspots, local glutamate and NE release are mutually enhancing and amplify activation of prioritized representations. In contrast, arousal-induced LC activity inhibits less active representations via two mechanisms: 1) Where there are hotspots, lateral inhibition is amplified; 2) Where no hotspots emerge, NE levels are only high enough to activate low-threshold inhibitory adrenoreceptors. Thus, LC activation promotes a few hotspots of excitation in the context of widespread suppression, enhancing high priority representations while suppressing the rest. Hotspots also help synchronize oscillations across neural ensembles transmitting high-priority information. Furthermore, brain structures that detect stimulus priority interact with phasic NE release to preferentially route such information through large-scale functional brain networks. A surge of NE before, during, or after encoding enhances synaptic plasticity at NE hotspots, triggering local protein synthesis processes that enhance selective memory consolidation. Together, these noradrenergic mechanisms promote selective attention and memory under arousal. GANE not only reconciles apparently contradictory findings in the emotion-cognition literature but also extends previous influential theories of LC neuromodulation by proposing specific mechanisms for how LC-NE activity increases neural gain.

  9. Myocardial imaging with a radioiodinated norepinephrine storage analog

    International Nuclear Information System (INIS)

    Wieland, D.M.; Brown, L.E.; Rogers, W.L.; Worthington, K.C.; Wu, J.L.; Clinthorne, N.H.; Otto, C.A.; Swanson, D.P.; Beierwaltes, W.H.

    1981-01-01

    Meta-iodobenzylguanidine (M-IBG), an iodinated aromatic analog of the hypotensive drug guanethidine, localizes in the heart of the rat, dog, and rhesus monkey. A comparative study of tissue distribution in the dog has been performed with five myocardiophilic agents: thallium-201, I-125 16-iodohexadecanoic acid, H-3 norepinephrine, C-14 guanethidine and I-125 M-IBG. The last two compounds give heart concentrations and heart-to-blood concentration ratios similar to those of thallium-201. Planar and tomographic images of the hearts of the dog and rhesus monkey were obtained using I-131 or I-123 labeled M-IBG. Blocking studies with reserpine suggest that a major component of myocardial retention of M-IBG is sequestration within the norepinephrine storage vesicles of the adrenergic nerves. The localization of M-IBG in other organs with rich sympathetic innervation and the relative insensitivity of myocardial uptake to a wide range of loading doses lend additional support for a neuronal mode of retention

  10. KCl stimulation increases norepinephrine transporter function in PC12 cells.

    Science.gov (United States)

    Mandela, Prashant; Ordway, Gregory A

    2006-09-01

    The norepinephrine transporter (NET) plays a pivotal role in terminating noradrenergic signaling and conserving norepinephrine (NE) through the process of re-uptake. Recent evidence suggests a close association between NE release and regulation of NET function. The present study evaluated the relationship between release and uptake, and the cellular mechanisms that govern these processes. KCl stimulation of PC12 cells robustly increased [3H]NE uptake via the NET and simultaneously increased [3H]NE release. KCl-stimulated increases in uptake and release were dependent on Ca2+. Treatment of cells with phorbol-12-myristate-13-acetate (PMA) or okadaic acid decreased [3H]NE uptake but did not block KCl-stimulated increases in [3H]NE uptake. In contrast, PMA increased [3H]NE release and augmented KCl-stimulated release, while okadaic acid had no effects on release. Inhibition of Ca2+-activated signaling cascades with KN93 (a Ca2+ calmodulin-dependent kinase inhibitor), or ML7 and ML9 (myosin light chain kinase inhibitors), reduced [3H]NE uptake and blocked KCl-stimulated increases in uptake. In contrast, KN93, ML7 and ML9 had no effect on KCl-stimulated [3H]NE release. KCl-stimulated increases in [3H]NE uptake were independent of transporter trafficking to the plasma membrane. While increases in both NE release and uptake mediated by KCl stimulation require Ca2+, different intracellular mechanisms mediate these two events.

  11. Synaptic Effects of Electric Fields

    Science.gov (United States)

    Rahman, Asif

    Learning and sensory processing in the brain relies on the effective transmission of information across synapses. The strength and efficacy of synaptic transmission is modifiable through training and can be modulated with noninvasive electrical brain stimulation. Transcranial electrical stimulation (TES), specifically, induces weak intensity and spatially diffuse electric fields in the brain. Despite being weak, electric fields modulate spiking probability and the efficacy of synaptic transmission. These effects critically depend on the direction of the electric field relative to the orientation of the neuron and on the level of endogenous synaptic activity. TES has been used to modulate a wide range of neuropsychiatric indications, for various rehabilitation applications, and cognitive performance in diverse tasks. How can a weak and diffuse electric field, which simultaneously polarizes neurons across the brain, have precise changes in brain function? Designing therapies to maximize desired outcomes and minimize undesired effects presents a challenging problem. A series of experiments and computational models are used to define the anatomical and functional factors leading to specificity of TES. Anatomical specificity derives from guiding current to targeted brain structures and taking advantage of the direction-sensitivity of neurons with respect to the electric field. Functional specificity originates from preferential modulation of neuronal networks that are already active. Diffuse electric fields may recruit connected brain networks involved in a training task and promote plasticity along active synaptic pathways. In vitro, electric fields boost endogenous synaptic plasticity and raise the ceiling for synaptic learning with repeated stimulation sessions. Synapses undergoing strong plasticity are preferentially modulated over weak synapses. Therefore, active circuits that are involved in a task could be more susceptible to stimulation than inactive circuits

  12. Synthesis and structure-distribution study of radioiodinated norepinephrine storage analogs

    Energy Technology Data Exchange (ETDEWEB)

    Wieland, D.M.; Inbasekaran, M.; Brown, L.E.; Marsh, D.D.; Beierwaltes, W.H. (Michigan Univ., Ann Arbor (USA). Medical Center)

    Unlabelled analogs of norepinephrine have been synthesised and then labelled with /sup 125/I in an attempt to find an agent with heart uptake and neuronal specificity greater than metaiodobenzylguanidine (MIBG). The analogs of norepinephrine were injected intravenously into dogs and showed a heart concentration similar to MIBG. Neuronal specificity of some analogs is being evaluated in rat heart.

  13. Synthesis and structure-distribution study of radioiodinated norepinephrine storage analogs

    International Nuclear Information System (INIS)

    Wieland, D.M.; Inbasekaran, M.; Brown, L.E.; Marsh, D.D.; Beierwaltes, W.H.

    1982-01-01

    Unlabelled analogs of norepinephrine have been synthesised and then labelled with 125 I in an attempt to find an agent with heart uptake and neuronal specificity greater than metaiodobenzylguanidine (MIBG). The analogs of norepinephrine were injected intravenously into dogs and showed a heart concentration similar to MIBG. Neuronal specificity of some analogs is being evaluated in rat heart. (U.K.)

  14. Optogenetic acidification of synaptic vesicles and lysosomes.

    Science.gov (United States)

    Rost, Benjamin R; Schneider, Franziska; Grauel, M Katharina; Wozny, Christian; Bentz, Claudia; Blessing, Anja; Rosenmund, Tanja; Jentsch, Thomas J; Schmitz, Dietmar; Hegemann, Peter; Rosenmund, Christian

    2015-12-01

    Acidification is required for the function of many intracellular organelles, but methods to acutely manipulate their intraluminal pH have not been available. Here we present a targeting strategy to selectively express the light-driven proton pump Arch3 on synaptic vesicles. Our new tool, pHoenix, can functionally replace endogenous proton pumps, enabling optogenetic control of vesicular acidification and neurotransmitter accumulation. Under physiological conditions, glutamatergic vesicles are nearly full, as additional vesicle acidification with pHoenix only slightly increased the quantal size. By contrast, we found that incompletely filled vesicles exhibited a lower release probability than full vesicles, suggesting preferential exocytosis of vesicles with high transmitter content. Our subcellular targeting approach can be transferred to other organelles, as demonstrated for a pHoenix variant that allows light-activated acidification of lysosomes.

  15. Norepinephrine spillover from skeletal muscle during exercise in humans

    DEFF Research Database (Denmark)

    Savard, G K; Richter, Erik; Strange, S

    1989-01-01

    The purpose of this study was to determine the effect of increasing muscle mass involvement in dynamic exercise on both sympathetic nervous activation and local hemodynamic variables of individual active and inactive skeletal muscle groups. Six male subjects performed 15-min bouts of one...... legs, with a steeper rise occurring approximately 70% VO2max. These increases were not associated with any significant changes in leg blood flow or leg vascular conductance at the exercise intensities examined. These results suggest that, as the total active muscle mass increases, the rise...... in both legs. Arterial and venous plasma concentrations of norepinephrine (NE) and epinephrine were analyzed, and the calculated NE spillover was used as an index of sympathetic nervous activity to the limb. NE spillover increased gradually both in the resting, and to a larger extent in the exercising...

  16. Depletion of rat cortical norepinephrine and the inhibition of [3H]norepinephrine uptake by xylamine does not require monoamine oxidase activity

    International Nuclear Information System (INIS)

    Dudley, M.W.

    1988-01-01

    Inhibition of monoamine oxidase A through pretreatment of rats with clorgyline or the pro-drug MDL 72,394 did not block the amine-depleting action of xylamine. Xylamine treatment resulted in a loss of approximately 60% of the control level of norepinephrine in the cerebral cortex. A 1-hr pretreatment, but not a 24-hr pretreatment, with the monoamine oxidase B inhibitor, L-deprenyl, prevented the depletion of norepinephrine by xylamine. In addition, pretreatment with MDL 72,974, a monoamine oxidase B inhibitor without amine-releasing or uptake - inhibiting effects, did not prevent cortical norepinephrine levels. Inhibition of monoamine oxidase by either MDL 72,974 or MDL 72,394 did not prevent the inhibition of [ 3 H]norepinephrine uptake into rat cortical synaptosomes by xylamine. These data indicate that monoamine oxidase does not mediate the amine-releasing or uptake inhibiting properties of xylamine. The protection afforded by L-deprenyl following a 1-hr pretreatment most probably was due to accumulation of its metabolite, L-amphetamine, which would inhibit the uptake carrier. A functional carrier is required for depletion since desipramine administered 1 hr prior to xylamine, was also able to prevent depletion of norepinephrine

  17. Positron emission tomography shows high specific uptake of racemic carbon-11 labelled norepinephrine in the primate heart

    International Nuclear Information System (INIS)

    Farde, L.; Halldin, C.; Naagren, K.; Suhara, Tetsuya; Karlsson, P.; Schoeps, K.O.; Swahn, C.G.; Bone, D.

    1994-01-01

    (-)-Norepinephrine is the predominant neurotransmitter of the sympathetic innervation of the heart. Racemic norepinephrine was labelled with carbon-11 and injected i.v. into Cynomolgus monkeys. Five minutes after injection there was a more than tenfold higher radioactivity in the heart than in adjacent tissue. Pretreatment with the norepinephrine reuptake inhibitor desipramine reduced the uptake by more than 80%. The high specific uptake of racemic [ 11 C]norepinephrine indicates that enatiomerically pure(-)-[ 11 C]norepinephrine has promising potential for detailed mapping of the sympathetic innervation of the human myocardium. (orig.)

  18. Positron emission tomography shows high specific uptake of racemic carbon-11 labelled norepinephrine in the primate heart

    Energy Technology Data Exchange (ETDEWEB)

    Farde, L [Dept. of Clinical Neuroscience, Karolinska Inst., Stockholm (Sweden); Halldin, C [Dept. of Clinical Neuroscience, Karolinska Inst., Stockholm (Sweden); Naagren, K [Turku Univ., Cyclotron/PET Center (Finland); Suhara, Tetsuya [Dept. of Clinical Neuroscience, Karolinska Inst., Stockholm (Sweden); Karlsson, P [Dept. of Clinical Neuroscience, Karolinska Inst., Stockholm (Sweden); Schoeps, K O [Dept. of Clinical Neuroscience, Karolinska Inst., Stockholm (Sweden); Swahn, C G [Dept. of Clinical Neuroscience, Karolinska Inst., Stockholm (Sweden); Bone, D [Dept. of Clinical Neuroscience, Karolinska Inst., Stockholm (Sweden)

    1994-04-01

    (-)-Norepinephrine is the predominant neurotransmitter of the sympathetic innervation of the heart. Racemic norepinephrine was labelled with carbon-11 and injected i.v. into Cynomolgus monkeys. Five minutes after injection there was a more than tenfold higher radioactivity in the heart than in adjacent tissue. Pretreatment with the norepinephrine reuptake inhibitor desipramine reduced the uptake by more than 80%. The high specific uptake of racemic [[sup 11]C]norepinephrine indicates that enatiomerically pure(-)-[[sup 11]C]norepinephrine has promising potential for detailed mapping of the sympathetic innervation of the human myocardium. (orig.)

  19. Synaptic dysfunction in amygdala in intellectual disorder models.

    Science.gov (United States)

    Aincy, Marianne; Meziane, Hamid; Herault, Yann; Humeau, Yann

    2018-06-08

    The amygdala is a part of the limbic circuit that has been extensively studied in terms of synaptic connectivity, plasticity and cellular organization since decades (Ehrlich et al., 2009; Ledoux, 2000; Maren, 2001). Amygdala sub-nuclei, including lateral, basolateral and central amygdala appear now as "hubs" providing in parallel and in series neuronal processing enabling the animal to elicit freezing or escaping behavior in response to external threats. In rodents, these behaviors are easily observed and quantified following associative fear conditioning. Thus, studies on amygdala circuit in association with threat/fear behavior became very popular in laboratories and are often used among other behavioral tests to evaluate learning abilities of mouse models for various neuropsychiatric conditions including genetically encoded intellectual disabilities (ID). Yet, more than 100 human X-linked genes - and several hundreds of autosomal genes - have been associated with ID in humans. These mutations introduced in mice can generate social deficits, anxiety dysregulations and fear learning impairments (McNaughton et al., 2008; Houbaert et al., 2013; Jayachandran et al., 2014; Zhang et al., 2015). Noteworthy, a significant proportion of the coded ID gene products are synaptic proteins. It is postulated that the loss of function of these proteins could destabilize neuronal circuits by global changes of the balance between inhibitory and excitatory drives onto neurons. However, whereas amygdala related behavioral deficits are commonly observed in ID models, the role of most of these ID-genes in synaptic function and plasticity in the amygdala are only sparsely studied. We will here discuss some of the concepts that emerged from amygdala-targeted studies examining the role of syndromic and non-syndromic ID genes in fear-related behaviors and/or synaptic function. Along describing these cases, we will discuss how synaptic deficits observed in amygdala circuits could impact

  20. Norepinephrine storage, distribution, and release in diabetic cardiomyopathy

    International Nuclear Information System (INIS)

    Ganguly, P.K.; Beamish, R.E.; Dhalla, K.S.; Innes, J.R.; Dhalla, N.S.

    1987-01-01

    The ability of hearts to store, distribute, and release norepinephrine (NE) was investigated in rats 8 wk after the induction of diabetes by an injection of streptozotocin. Chronic diabetes was associated with increased content and concentration of NE in heart and in other tissues such as kidney, brain, and spleen. Reserpine or tyramine treatment resulted in depletion of endogenous cardiac NE in control and diabetic rats. The depletion of NE stores at different times after a dose of reserpine was greater in diabetic hearts. On the other hand, NE stores in diabetic hearts were less sensitive than control hearts to low doses of tyramine but were more sensitive to high doses. The uptake of [ 3 H]NE was greater in diabetic hearts in isolated perfused preparations. In comparison with the control values, diabetic hearts showed a decrease in [ 3 H]NE in the granular fraction and an increase in the supernatant fraction. Diabetic hearts also showed an accelerated spontaneous release of [ 3 H]NE. The increased cardiac NE and the uptake and release of NE in diabetic animals were reversible upon treatment with insulin. These results are consistent with the view that sympathetic activity is increased in diabetic cardiomyopathy and indicate that cardiac NE in diabetic rats is maintained at a higher level partly due to an increased uptake of released NE by adrenergic nerve terminals

  1. Beta blockers, norepinephrine, and cancer: an epidemiological viewpoint

    Directory of Open Access Journals (Sweden)

    Fitzgerald PJ

    2012-06-01

    Full Text Available Paul J FitzgeraldThe Zanvyl Krieger Mind/Brain Institute, Solomon H Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD, USAAbstract: There is growing evidence that the neurotransmitter norepinephrine (NE and its sister molecule epinephrine (EPI (adrenaline affect some types of cancer. Several recent epidemiological studies have shown that chronic use of beta blocking drugs (which antagonize NE/EPI receptors results in lower recurrence, progression, or mortality of breast cancer and malignant melanoma. Preclinical studies have shown that manipulation of the levels or receptors of NE and EPI with drugs affects experimentally induced cancers. Psychological stress may play an etiological role in some cases of cancer (which has been shown epidemiologically, and this could be partly mediated by NE and EPI released by the sympathetic nervous system as part of the body’s “fight or flight” response. A less well-appreciated phenomenon is that the genetic tone of NE/EPI may play a role in cancer. NE and EPI may affect cancer by interacting with molecular pathways already implicated in abnormal cellular replication, such as the P38/MAPK pathway, or via oxidative stress. NE/EPI-based drugs other than beta blockers also may prevent or treat various types of cancer, as may cholinesterase inhibitors that inhibit the sympathetic nervous system, which could be tested epidemiologically.Keywords: clonidine, guanfacine, aspirin, acetylcholine, epinephrine, adrenaline, sympathetic nervous system, parasympathetic nervous system, inflammation

  2. Angiotensin receptors and norepinephrine neuromodulation: implications of functional coupling.

    Science.gov (United States)

    Gelband, C H; Sumners, C; Lu, D; Raizada, M K

    1998-02-27

    The objective of this review is to examine the role of neuronal angiotensin II (Ang II) receptors in vitro. Two types of G protein-coupled Ang II receptors have been identified in cardiovascularly relevant areas of the brain: the AT1 and the AT2. We have utilized neurons in culture to study the signaling mechanisms of AT1 and AT2 receptors. Neuronal AT1 receptors are involved in norepinephrine (NE) neuromodulation. NE neuromodulation can be either evoked or enhanced. Evoked NE neuromodulation involves AT1 receptor-mediated, losartan-dependent, rapid NE release, inhibition of K+ channels and stimulation of Ca2+ channels. AT1 receptor-mediated enhanced NE neuromodulation involves the Ras-Raf-MAP kinase cascade and ultimately leads to an increase in NE transporter, tyrosine hydroxylase and dopamine beta-hydroxylase mRNA transcription. Neuronal AT2 receptors signal via a Gi protein and are coupled to activation of PP2A and PLA2 and stimulation of K+ channels. Finally, putative cross-talk pathways between AT1 and AT2 receptors will be discussed.

  3. Norepinephrine metabolism in neuronal cultures is increased by angiotensin II

    International Nuclear Information System (INIS)

    Sumners, C.; Shalit, S.L.; Kalberg, C.J.; Raizada, M.K.

    1987-01-01

    In this study the authors have examined the actions of angiotensin II (ANG II) on catecholamine metabolism in neuronal brain cell cultures prepared from the hypothalamus and brain stem. Neuronal cultures prepared from the brains of 1-day-old Sprague-Dawley rats exhibit specific neuronal uptake mechanisms for both norepinephrine (NE) and dopamine (DA), and also monoamine oxidase (MAO) and catechol O-methyltransferase (COMT) activity. Separate neuronal uptake sites for NE and DA were identified by using specific neuronal uptake inhibitors for each amine. In previous studies, they determined that ANG II (10 nM-1 μM) stimulates increased neuronal [ 3 H]NE uptake by acting as specific receptors. They have confirmed these results here and in addition have shown that ANG II has not significant effects on neuronal [ 3 H]DA uptake. These results suggest that the actions of ANG II are restricted to the NE transporter in neuronal cultures. It is possible that ANG II stimulates the intraneuronal metabolism of at least part of the NE that is taken up, because the peptide stimulates MAO activity, an effect mediated by specific ANG II receptors. ANG II had no effect on COMT activity in neuronal cultures. Therefore, the use of neuronal cultures of hypothalamus and brain stem they have determined that ANG II can specifically alter NE metabolism in these areas, while apparently not altering DA metabolism

  4. Orienting of attention, pupil size, and the norepinephrine system.

    Science.gov (United States)

    Gabay, Shai; Pertzov, Yoni; Henik, Avishai

    2011-01-01

    This research examined a novel suggestion regarding the involvement of the locus coeruleus-norepinephrine (LC-NE) system in orienting reflexive (exogenous) attention. A common procedure for studying exogenous orienting of attention is Posner's cuing task. Importantly, one can manipulate the required level of target processing by changing task requirements, which, in turn, can elicit a different time course of inhibition of return (IOR). An easy task (responding to target location) produces earlier onset IOR, whereas a demanding task (responding to target identity) produces later onset IOR. Aston-Jones and Cohen (Annual Review of Neuroscience, 28, 403-450, 2005) presented a theory suggesting two different modes of LC activity: tonic and phasic. Accordingly, we suggest that in the more demanding task, the LC-NE system is activated in phasic mode, and in the easier task, it is activated in tonic mode. This, in turn, influences the appearance of IOR. We examined this suggestion by measuring participants' pupil size, which has been demonstrated to correlate with the LC-NE system, while they performed cuing tasks. We found a response-locked phasic dilation of the pupil in the discrimination task, as compared with the localization task, which may reflect different firing modes of the LC-NE system during the two tasks. We also demonstrated a correlation between pupil size at the time of cue presentation and magnitude of IOR.

  5. Epinephrine in the heart: uptake and release, but no facilitation of norepinephrine release

    NARCIS (Netherlands)

    Th.W. Lameris (Thomas); P.A. de Zeeuw (Sandra); D.J.G.M. Duncker (Dirk); W. Tietge; G. Alberts; F. Boomsma (Frans); P.D. Verdouw (Pieter); A.H. van den Meiracker (Anton)

    2002-01-01

    textabstractBACKGROUND: Several studies have suggested that epinephrine augments the release of norepinephrine from sympathetic nerve terminals through stimulation of presynaptic receptors, but evidence pertaining to this mechanism in the heart is scarce and conflicting. Using

  6. Kinetics of the norepinephrine analog [76Br]-meta-bromobenzylguanidine in isolated working rat heart

    International Nuclear Information System (INIS)

    Raffel, David; Loc'h, Christian; Mardon, Karine; Maziere, Bernard; Syrota, Andre

    1998-01-01

    A related set of kinetic studies of the norepinephrine analog [ 76 Br]-meta-bromobenzylguanidine (MBBG) were performed with an isolated working rat heart preparation. A series of constant infusion studies over a wide range of MBBG concentrations allowed estimation of the Michaelis-Menten constants for transport by the neuronal norepinephrine transporter (uptake 1 ) and the extraneuronal uptake system (uptake 2 ). Pharmacological blocking studies with inhibitors of uptake 1 , uptake 2 and vesicular uptake were performed to delineate the relative importance of these norepinephrine handling mechanisms on the kinetics of MBBG in the rat heart. Bolus injection studies were done to assess the ability of compartmental modeling techniques to characterize the kinetics of MBBG. These studies demonstrate that MBBG shares many of the same uptake mechanisms as norepinephrine in the rat heart. PET imaging studies with MBBG would be useful for assessing sympathetic nerve status in the living human heart

  7. Effect of atropine, norepinephrine and phenylephrine on cerebral oxygenation and cardiac output during anesthesia.

    NARCIS (Netherlands)

    Kalmar, A.F.; Poterman, Marieke; Mooyaart, E.A.; Struys, Michel; Scheeren, Thomas

    2012-01-01

    Background:  Induction of general anesthesia often induces unwanted hypotension which is commonly treated with vasoactive medication to restore an appropriate blood pressure. Phenylephrine, norepinephrine and atropine are commonly used agents for this purpose with different physiological effects.

  8. Is cerebral oxygenation negatively affected by infusion of norepinephrine in healthy subjects?

    DEFF Research Database (Denmark)

    Brassard, P.; Seifert, T.; Secher, Niels H.

    2009-01-01

    BACKGROUND: Vasopressor agents are commonly used to increase mean arterial pressure (MAP) in order to secure a pressure gradient to perfuse vital organs. The influence of norepinephrine on cerebral oxygenation is not clear. The aim of this study was to evaluate the impact of the infusion of norep......BACKGROUND: Vasopressor agents are commonly used to increase mean arterial pressure (MAP) in order to secure a pressure gradient to perfuse vital organs. The influence of norepinephrine on cerebral oxygenation is not clear. The aim of this study was to evaluate the impact of the infusion...... of norepinephrine on cerebral oxygenation in healthy subjects. METHODS: Three doses of norepinephrine (0.05, 0.1, and 0.15 microg kg(-1) min(-1) for 20 min each) were infused in nine healthy subjects [six males; 26 (6) yr, mean (SD)]. MAP, cerebral oxygenation characterized by frontal lobe oxygenation (Sc(O2...

  9. Reward dependence is related to norepinephrine transporter T-182C gene polymorphism in a Korean population.

    Science.gov (United States)

    Ham, Byung-Joo; Choi, Myoung-Jin; Lee, Heon-Jeong; Kang, Rhee-Hun; Lee, Min-Soo

    2005-06-01

    It is well established that approximately 50% of the variance in personality traits is genetic. The goal of this study was to investigate a relationship between personality traits and the T-182C polymorphism in the norepinephrine transporter gene. The participants included 115 healthy adults with no history of psychiatric disorders and other physical illness during the past 6 months. All participants were tested with the Temperament and Character Inventory and genotyped norepinephrine transporter gene polymorphism. Differences on the Temperament and Character Inventory dimensions among three groups were examined with one-way analysis of variance. Our study suggests that the norepinephrine transporter T-182C gene polymorphism is associated with reward dependence in Koreans, but the small number of study participants and their sex and age heterogeneity limits generalization of our results. Further studies are necessary with a larger number of homogeneous participants to confirm whether the norepinephrine transporter gene is related to personality traits.

  10. Synaptic communication between neurons and NG2+ cells.

    Science.gov (United States)

    Paukert, Martin; Bergles, Dwight E

    2006-10-01

    Chemical synaptic transmission provides the basis for much of the rapid signaling that occurs within neuronal networks. However, recent studies have provided compelling evidence that synapses are not used exclusively for communication between neurons. Physiological and anatomical studies indicate that a distinct class of glia known as NG2(+) cells also forms direct synaptic junctions with both glutamatergic and GABAergic neurons. Glutamatergic signaling can influence intracellular Ca(2+) levels in NG2(+) cells by activating Ca(2+) permeable AMPA receptors, and these inputs can be potentiated through high frequency stimulation. Although the significance of this highly differentiated form of communication remains to be established, these neuro-glia synapses might enable neurons to influence rapidly the behavior of this ubiquitous class of glial progenitors.

  11. Why we forget our dreams: Acetylcholine and norepinephrine in wakefulness and REM sleep.

    Science.gov (United States)

    Becchetti, Andrea; Amadeo, Alida

    2016-01-01

    The ascending fibers releasing norepinephrine and acetylcholine are highly active during wakefulness. In contrast, during rapid-eye-movement sleep, the neocortical tone is sustained mainly by acetylcholine. By comparing the different physiological features of the norepinephrine and acetylcholine systems in the light of the GANE (glutamate amplifies noradrenergic effects) model, we suggest how to interpret some functional differences between waking and rapid-eye-movement sleep.

  12. Fluid loading and norepinephrine infusion mask the left ventricular preload decrease induced by pleural effusion

    DEFF Research Database (Denmark)

    Wemmelund, Kristian Borup; Ringgård, Viktor Kromann; Vistisen, Simon Tilma

    2017-01-01

    BACKGROUND: Pleural effusion (PLE) may lead to low blood pressure and reduced cardiac output. Low blood pressure and reduced cardiac output are often treated with fluid loading and vasopressors. This study aimed to determine the impact of fluid loading and norepinephrine infusion on physiologic d...... global haemodynamic parameters. Inferior vena cava distensibility remained unchanged. The haemodynamic significance of PLE may be underestimated during fluid or norepinephrine administration, potentially masking the presence of PLE....

  13. Norepinephrine turnover in brown adipose tissue is stimulated by a single meal

    International Nuclear Information System (INIS)

    Glick, Z.; Raum, W.J.

    1986-01-01

    A single meal stimulates brown adipose tissue (BAT) thermogenesis in rats. In the present study the role of norepinephrine in this thermogenic response was assessed from the rate of its turnover in BAT after a single test meal. For comparison, norepinephrine turnover was determined in the heart and spleen. A total of 48 male Wistar rats (200 g) were trained to eat during two feeding sessions per day. On the experimental day, one group (n = 24) was meal deprived and the other (n = 24) was given a low-protein high-carbohydrate test meal for 2 h. The synthesis inhibition method with α-methyl-p-tyrosine was employed to determine norepinephrine turnover from its concentration at four hourly time points after the meal. Tissue concentrations of norepinephrine were determined by radioimmunoassay. Norepinephrine concentration and turnover rate were increased more than threefold in BAT of the meal-fed compared with the meal-deprived rats. Neither were significantly altered by the meal in the heart or spleen. The data suggest that norepinephrine mediates a portion of the thermic effect of meals that originate in BAT

  14. Dopamine versus norepinephrine in the treatment of cardiogenic shock: A PRISMA-compliant meta-analysis.

    Science.gov (United States)

    Rui, Qing; Jiang, Yufeng; Chen, Min; Zhang, Nannan; Yang, Huajia; Zhou, Yafeng

    2017-10-01

    Guidelines recommend that norepinephrine (NA) should be used to reach the target mean arterial pressure (MAP) during cardiogenic shock (CS), rather than epinephrine and dopamine (DA). However, there has actually been few studies on comparing norepinephrine with dopamine and their results conflicts. These studies raise a heat discussion. This study aimed to validate the effectiveness of norepinephrine for treating CS in comparison with dopamine. We performed a meta-analysis of randomized controlled trials (RCTs) to assess pooled estimates of risk ratio (RR) and 95% confidence interval (CI) for 28-day mortality, incidence of arrhythmic events, gastrointestinal reaction, and some indexes after treatment. Compared with dopamine, patients receiving norepinephrine had a lower 28-day mortality (RR 1.611 [95% CI 1.219-2.129]; P dopamine in 2 subgroups. Our analysis revealed that norepinephrine was associated with a lower 28-day mortality, a lower risk of arrhythmic events, and gastrointestinal reaction. No matter whether CS is caused by coronary heart disease or not, norepinephrine is superior to dopamine for correcting CS on the 28-day mortality.

  15. Norepinephrine stimulates mobilization of endothelial progenitor cells after limb ischemia.

    Directory of Open Access Journals (Sweden)

    Qijun Jiang

    Full Text Available OBJECTIVE: During several pathological processes such as cancer progression, thermal injury, wound healing and hindlimb ischemia, the mobilization of endothelial progenitor cells (EPCs mobilization was enhanced with an increase of sympathetic nerve activity and norepinephrine (NE secretion, yet the cellular and molecular mechanisms involved in the effects of NE on EPCs has less been investigated. METHODS AND RESULTS: EPCs from BMs, peripheral circulation and spleens, the VEGF concentration in BM, skeletal muscle, peripheral circulation and spleen and angiogenesis in ischemic gastrocnemius were quantified in mice with hindlimbs ischemia. Systemic treatment of NE significantly increased EPCs number in BM, peripheral circulation and spleen, VEGF concentration in BM and skeletal muscle and angiogenesis in ischemic gastrocnemius in mice with hind limb ischemia, but did not affair VEGF concentration in peripheral circulation and spleen. EPCs isolated from healthy adults were cultured with NE in vitro to evaluate proliferation potential, migration capacity and phosphorylations of Akt and eNOS signal moleculars. Treatment of NE induced a significant increase in number of EPCs in the S-phase in a dose-dependent manner, as well as migrative activity of EPCs in vitro (p<0.05. The co-treatment of Phentolamine, I127, LY294002 and L-NAME with NE blocked the effects of NE on EPCs proliferation and migration. Treatment with NE significantly increased phosphorylation of Akt and eNOS of EPCs. Addition of phentolamine and I127 attenuated the activation of Akt/eNOS pathway, but metoprolol could not. Pretreatment of mice with either Phentolamine or I127 significantly attenuated the effects of NE on EPCs in vivo, VEGF concentration in BM, skeletal muscle and angiogenesis in ischemic gastrocnemius, but Metoprolol did not. CONCLUSION: These results unravel that sympathetic nervous system regulate EPCs mobilization and their pro-angiogenic capacity via α adrenoceptor

  16. Norepinephrine metabolism in humans. Kinetic analysis and model

    International Nuclear Information System (INIS)

    Linares, O.A.; Jacquez, J.A.; Zech, L.A.; Smith, M.J.; Sanfield, J.A.; Morrow, L.A.; Rosen, S.G.; Halter, J.B.

    1987-01-01

    The present study was undertaken to quantify more precisely and to begin to address the problem of heterogeneity of the kinetics of distribution and metabolism of norepinephrine (NE) in humans, by using compartmental analysis. Steady-state NE specific activity in arterialized plasma during [ 3 H]NE infusion and postinfusion plasma disappearance of [ 3 H]NE were measured in eight healthy subjects in the supine and upright positions. Two exponentials were clearly identified in the plasma [ 3 H]NE disappearance curves of each subject studied in the supine (r = 0.94-1.00, all P less than 0.01) and upright (r = 0.90-0.98, all P less than 0.01) positions. A two-compartment model was the minimal model necessary to simultaneously describe the kinetics of NE in the supine and upright positions. The NE input rate into the extravascular compartment 2, estimated with the minimal model, increased with upright posture (1.87 +/- 0.08 vs. 3.25 +/- 0.2 micrograms/min per m2, P less than 0.001). Upright posture was associated with a fall in the volume of distribution of NE in compartment 1 (7.5 +/- 0.6 vs. 4.7 +/- 0.3 liters, P less than 0.001), and as a result of that, there was a fall in the metabolic clearance rate of NE from compartment 1 (1.80 +/- 0.11 vs. 1.21 +/- 0.08 liters/min per m2, P less than 0.001). We conclude that a two-compartment model is the minimal model that can accurately describe the kinetics of distribution and metabolism of NE in humans

  17. Norepinephrine transporter inhibition alters the hemodynamic response to hypergravitation.

    Science.gov (United States)

    Strempel, Sebastian; Schroeder, Christoph; Hemmersbach, Ruth; Boese, Andrea; Tank, Jens; Diedrich, André; Heer, Martina; Luft, Friedrich C; Jordan, Jens

    2008-03-01

    Sympathetically mediated tachycardia and vasoconstriction maintain blood pressure during hypergravitational stress, thereby preventing gravitation-induced loss of consciousness. Norepinephrine transporter (NET) inhibition prevents neurally mediated (pre)syncope during gravitational stress imposed by head-up tilt testing. Thus it seems reasonable that NET inhibition could increase tolerance to hypergravitational stress. We performed a double-blind, randomized, placebo-controlled crossover study in 11 healthy men (26 +/- 1 yr, body mass index 24 +/- 1 kg/m2), who ingested the selective NET inhibitor reboxetine (4 mg) or matching placebo 25, 13, and 1 h before testing on separate days. We monitored heart rate, blood pressure, and thoracic impedance in three different body positions (supine, seated, standing) and during a graded centrifuge run (incremental steps of 0.5 g for 3 min each, up to a maximal vertical acceleration load of 3 g). NET inhibition increased supine blood pressure and heart rate. With placebo, blood pressure increased in the seated position and was well maintained during standing. However, with NET inhibition, blood pressure decreased in the seated and standing position. During hypergravitation, blood pressure increased in a graded fashion with placebo. With NET inhibition, the increase in blood pressure during hypergravitation was profoundly diminished. Conversely, the tachycardic responses to sitting, standing, and hypergravitation all were greatly increased with NET inhibition. In contrast to our expectation, short-term NET inhibition did not improve tolerance to hypergravitation. Redistribution of sympathetic activity to the heart or changes in baroreflex responses could explain the excessive tachycardia that we observed.

  18. Norepinephrine is coreleased with serotonin in mouse taste buds.

    Science.gov (United States)

    Huang, Yijen A; Maruyama, Yutaka; Roper, Stephen D

    2008-12-03

    ATP and serotonin (5-HT) are neurotransmitters secreted from taste bud receptor (type II) and presynaptic (type III) cells, respectively. Norepinephrine (NE) has also been proposed to be a neurotransmitter or paracrine hormone in taste buds. Yet, to date, the specific stimulus for NE release in taste buds is not well understood, and the identity of the taste cells that secrete NE is not known. Chinese hamster ovary cells were transfected with alpha(1A) adrenoceptors and loaded with fura-2 ("biosensors") to detect NE secreted from isolated mouse taste buds and taste cells. Biosensors responded to low concentrations of NE (>or=10 nm) with a reliable fura-2 signal. NE biosensors did not respond to stimulation with KCl or taste compounds. However, we recorded robust responses from NE biosensors when they were positioned against mouse circumvallate taste buds and the taste buds were stimulated with KCl (50 mm) or a mixture of taste compounds (cycloheximide, 10 microm; saccharin, 2 mm; denatonium, 1 mm; SC45647, 100 microm). NE biosensor responses evoked by stimulating taste buds were reversibly blocked by prazosin, an alpha(1A) receptor antagonist. Together, these findings indicate that taste bud cells secrete NE when they are stimulated. We isolated individual taste bud cells to identify the origin of NE release. NE was secreted only from presynaptic (type III) taste cells and not receptor (type II) cells. Stimulus-evoked NE release depended on Ca(2+) in the bathing medium. Using dual biosensors (sensitive to 5-HT and NE), we found all presynaptic cells secrete 5-HT and 33% corelease NE with 5-HT.

  19. Synaptic vesicle distribution by conveyor belt.

    Science.gov (United States)

    Moughamian, Armen J; Holzbaur, Erika L F

    2012-03-02

    The equal distribution of synaptic vesicles among synapses along the axon is critical for robust neurotransmission. Wong et al. show that the continuous circulation of synaptic vesicles throughout the axon driven by molecular motors ultimately yields this even distribution. Copyright © 2012 Elsevier Inc. All rights reserved.

  20. Spontaneous Vesicle Recycling in the Synaptic Bouton

    Directory of Open Access Journals (Sweden)

    Sven eTruckenbrodt

    2014-12-01

    Full Text Available The trigger for synaptic vesicle exocytosis is Ca2+, which enters the synaptic bouton following action potential stimulation. However, spontaneous release of neurotransmitter also occurs in the absence of stimulation in virtually all synaptic boutons. It has long been thought that this represents exocytosis driven by fluctuations in local Ca2+ levels. The vesicles responding to these fluctuations are thought to be the same ones that release upon stimulation, albeit potentially triggered by different Ca2+ sensors. This view has been challenged by several recent works, which have suggested that spontaneous release is driven by a separate pool of synaptic vesicles. Numerous articles appeared during the last few years in support of each of these hypotheses, and it has been challenging to bring them into accord. We speculate here on the origins of this controversy, and propose a solution that is related to developmental effects. Constitutive membrane traffic, needed for the biogenesis of vesicles and synapses, is responsible for high levels of spontaneous membrane fusion in young neurons, probably independent of Ca2+. The vesicles releasing spontaneously in such neurons are not related to other synaptic vesicle pools and may represent constitutively releasing vesicles (CRVs rather than bona fide synaptic vesicles. In mature neurons, constitutive traffic is much dampened, and the few remaining spontaneous release events probably represent bona fide spontaneously releasing synaptic vesicles (SRSVs responding to Ca2+ fluctuations, along with a handful of CRVs that participate in synaptic vesicle turnover.

  1. Active hippocampal networks undergo spontaneous synaptic modification.

    Directory of Open Access Journals (Sweden)

    Masako Tsukamoto-Yasui

    Full Text Available The brain is self-writable; as the brain voluntarily adapts itself to a changing environment, the neural circuitry rearranges its functional connectivity by referring to its own activity. How the internal activity modifies synaptic weights is largely unknown, however. Here we report that spontaneous activity causes complex reorganization of synaptic connectivity without any external (or artificial stimuli. Under physiologically relevant ionic conditions, CA3 pyramidal cells in hippocampal slices displayed spontaneous spikes with bistable slow oscillations of membrane potential, alternating between the so-called UP and DOWN states. The generation of slow oscillations did not require fast synaptic transmission, but their patterns were coordinated by local circuit activity. In the course of generating spontaneous activity, individual neurons acquired bidirectional long-lasting synaptic modification. The spontaneous synaptic plasticity depended on a rise in intracellular calcium concentrations of postsynaptic cells, but not on NMDA receptor activity. The direction and amount of the plasticity varied depending on slow oscillation patterns and synapse locations, and thus, they were diverse in a network. Once this global synaptic refinement occurred, the same neurons now displayed different patterns of spontaneous activity, which in turn exhibited different levels of synaptic plasticity. Thus, active networks continuously update their internal states through ongoing synaptic plasticity. With computational simulations, we suggest that with this slow oscillation-induced plasticity, a recurrent network converges on a more specific state, compared to that with spike timing-dependent plasticity alone.

  2. Chronic desipramine treatment alters tyrosine hydroxylase but not norepinephrine transporter immunoreactivity in norepinephrine axons in the rat prefrontal cortex

    Science.gov (United States)

    Erickson, Susan L.; Gandhi, Anjalika R.; Asafu-Adjei, Josephine K.; Sampson, Allan R.; Miner, LeeAnn; Blakely, Randy D.; Sesack, Susan R.

    2011-01-01

    Pharmacological blockade of norepinephrine (NE) reuptake is clinically effective in treating several mental disorders. Drugs that bind to the NE transporter (NET) alter both protein levels and activity of NET and also the catecholamine synthetic enzyme tyrosine hydroxylase (TH). We examined the rat prefrontal cortex (PFC) by electron microscopy to determine whether the density and subcellular distribution of immunolabeling for NET and colocalization of NET with TH within individual NE axons were altered by chronic treatment with the selective NE uptake inhibitor desipramine (DMI). Following DMI treatment (21 days, 15 mg/kg/day), NET-immunoreactive (-ir) axons were significantly less likely to colocalize TH. This finding is consistent with reports of reduced TH levels and activity in the locus coeruleus after chronic DMI and indicates a reduction of NE synthetic capacity in the PFC. Measures of NET expression and membrane localization, including the number of NET-ir profiles per tissue area sampled, the number of gold particles per NET-ir profile area, and the proportion of gold particles associated with the plasma membrane, were similar in DMI and vehicle treated rats. These findings were verified using two different antibodies directed against distinct epitopes of the NET protein. The results suggest that chronic DMI treatment does not reduce NET expression within individual NE axons in vivo or induce an overall translocation of NET protein away from the plasma membrane in the PFC as measured by ultrastructural immunogold labeling. Our findings encourage consideration of possible postranslational mechanisms for regulating NET activity in antidepressant-induced modulation of NE clearance. PMID:21208501

  3. Synaptic plasticity in drug reward circuitry.

    Science.gov (United States)

    Winder, Danny G; Egli, Regula E; Schramm, Nicole L; Matthews, Robert T

    2002-11-01

    Drug addiction is a major public health issue worldwide. The persistence of drug craving coupled with the known recruitment of learning and memory centers in the brain has led investigators to hypothesize that the alterations in glutamatergic synaptic efficacy brought on by synaptic plasticity may play key roles in the addiction process. Here we review the present literature, examining the properties of synaptic plasticity within drug reward circuitry, and the effects that drugs of abuse have on these forms of plasticity. Interestingly, multiple forms of synaptic plasticity can be induced at glutamatergic synapses within the dorsal striatum, its ventral extension the nucleus accumbens, and the ventral tegmental area, and at least some of these forms of plasticity are regulated by behaviorally meaningful administration of cocaine and/or amphetamine. Thus, the present data suggest that regulation of synaptic plasticity in reward circuits is a tractable candidate mechanism underlying aspects of addiction.

  4. Norepinephrine and Epinephrine Enhanced the Infectivity of Enterovirus 71.

    Directory of Open Access Journals (Sweden)

    Yu-Ting Liao

    Full Text Available Enterovirus 71 (EV71 infections may be associated with neurological complications, including brainstem encephalitis (BE. Severe EV71 BE may be complicated with autonomic nervous system (ANS dysregulation and/or pulmonary edema (PE. ANS dysregulation is related to the overactivation of the sympathetic nervous system, which results from catecholamine release.The aims of this study were to explore the effects of catecholamines on severe EV71 infection and to investigate the changes in the percentages of EV71-infected cells, virus titer, and cytokine production on the involvement of catecholamines.Plasma levels of norepinephrine (NE and epinephrine (EP in EV71-infected patients were measured using an enzyme-linked immunoassay. The expression of adrenergic receptors (ADRs on RD, A549, SK-N-SH, THP-1, Jurkat and human peripheral blood mononuclear cells (hPBMCs were detected using flow cytometry. The percentages of EV71-infected cells, virus titer, and cytokine production were investigated after treatment with NE and EP.The plasma levels of NE and EP were significantly higher in EV71-infected patients with ANS dysregulation and PE than in controls. Both α1A- and β2-ADRs were expressed on A549, RD, SK-N-SH, HL-60, THP-1, Jurkat cells and hPBMCs. NE treatment elevated the percentages of EV71-infected cells to 62.9% and 22.7% in THP-1 and Jurkat cells, respectively. Via treatment with EP, the percentages of EV71-infected cells were increased to 64.6% and 26.9% in THP-1 and Jurkat cells. The percentage of EV71-infected cells increased upon NE or EP treatment while the α- and β-blockers reduced the percentages of EV71-infected cells with NE or EP treatment. At least two-fold increase in virus titer was observed in EV71-infected A549, SK-N-SH and hPBMCs after treatment with NE or EP. IL-6 production was enhanced in EV71-infected hPBMCs at a concentration of 102 pg/mL NE.The plasma levels of NE and EP elevated in EV71-infected patients with ANS

  5. Norepinephrine and Epinephrine Enhanced the Infectivity of Enterovirus 71.

    Science.gov (United States)

    Liao, Yu-Ting; Wang, Shih-Min; Wang, Jen-Ren; Yu, Chun-Keung; Liu, Ching-Chuan

    2015-01-01

    Enterovirus 71 (EV71) infections may be associated with neurological complications, including brainstem encephalitis (BE). Severe EV71 BE may be complicated with autonomic nervous system (ANS) dysregulation and/or pulmonary edema (PE). ANS dysregulation is related to the overactivation of the sympathetic nervous system, which results from catecholamine release. The aims of this study were to explore the effects of catecholamines on severe EV71 infection and to investigate the changes in the percentages of EV71-infected cells, virus titer, and cytokine production on the involvement of catecholamines. Plasma levels of norepinephrine (NE) and epinephrine (EP) in EV71-infected patients were measured using an enzyme-linked immunoassay. The expression of adrenergic receptors (ADRs) on RD, A549, SK-N-SH, THP-1, Jurkat and human peripheral blood mononuclear cells (hPBMCs) were detected using flow cytometry. The percentages of EV71-infected cells, virus titer, and cytokine production were investigated after treatment with NE and EP. The plasma levels of NE and EP were significantly higher in EV71-infected patients with ANS dysregulation and PE than in controls. Both α1A- and β2-ADRs were expressed on A549, RD, SK-N-SH, HL-60, THP-1, Jurkat cells and hPBMCs. NE treatment elevated the percentages of EV71-infected cells to 62.9% and 22.7% in THP-1 and Jurkat cells, respectively. Via treatment with EP, the percentages of EV71-infected cells were increased to 64.6% and 26.9% in THP-1 and Jurkat cells. The percentage of EV71-infected cells increased upon NE or EP treatment while the α- and β-blockers reduced the percentages of EV71-infected cells with NE or EP treatment. At least two-fold increase in virus titer was observed in EV71-infected A549, SK-N-SH and hPBMCs after treatment with NE or EP. IL-6 production was enhanced in EV71-infected hPBMCs at a concentration of 102 pg/mL NE. The plasma levels of NE and EP elevated in EV71-infected patients with ANS dysregulation and

  6. Synaptic transmission modulates while non-synaptic processes govern the transition from pre-ictal to seizure activity in vitro

    OpenAIRE

    Jefferys, John; Fox, John; Jiruska, Premysl; Kronberg, Greg; Miranda, Dolores; Ruiz-Nuño, Ana; Bikson, Marom

    2018-01-01

    It is well established that non-synaptic mechanisms can generate electrographic seizures after blockade of synaptic function. We investigated the interaction of intact synaptic activity with non-synaptic mechanisms in the isolated CA1 region of rat hippocampal slices using the 'elevated-K+' model of epilepsy. Elevated K+ ictal bursts share waveform features with other models of electrographic seizures, including non-synaptic models where chemical synaptic transmission is suppressed, such as t...

  7. Norepinephrine transporter function and desipramine: residual drug effects versus short-term regulation.

    Science.gov (United States)

    Ordway, Gregory A; Jia, Weihong; Li, Jing; Zhu, Meng-Yang; Mandela, Prashant; Pan, Jun

    2005-04-30

    Previous research has shown that exposure of norepinephrine transporter (NET)-expressing cells to desipramine (DMI) downregulates the norepinephrine transporter, although changes in the several transporter parameters do not demonstrate the same time course. Exposures to desipramine for effects of residual desipramine on norepinephrine transporter binding and uptake were re-evaluated following exposures of PC12 cells to desipramine using different methods to remove residual drug. Using a method that minimizes residual drug, exposure of intact PC12 cells to desipramine for 4h had no effect on uptake capacity or [(3)H]nisoxetine binding to the norepinephrine transporter, while exposures for > or =16 h reduced uptake capacity. Desipramine-induced reductions in binding to the transporter required >24 h or greater periods of desipramine exposure. This study confirms that uptake capacity of the norepinephrine transporter is reduced earlier than changes in radioligand binding, but with a different time course than originally shown. Special pre-incubation procedures are required to abolish effects of residual transporter inhibitor when studying inhibitor-induced transporter regulation.

  8. Differential Internalization Rates and Postendocytic Sorting of the Norepinephrine and Dopamine Transporters Are Controlled by Structural Elements in the N Termini*

    Science.gov (United States)

    Vuorenpää, Anne; Jørgensen, Trine N.; Newman, Amy H.; Madsen, Kenneth L.; Scheinin, Mika

    2016-01-01

    The norepinephrine transporter (NET) mediates reuptake of synaptically released norepinephrine in central and peripheral noradrenergic neurons. The molecular processes governing availability of NET in the plasma membrane are poorly understood. Here we use the fluorescent cocaine analogue JHC 1-64, as well as several other approaches, to investigate the trafficking itinerary of NET in live noradrenergic neurons. Confocal imaging revealed extensive constitutive internalization of JHC 1-64-labeled NET in the neuronal somata, proximal extensions and presynaptic boutons. Phorbol 12-myristate 13-acetate increased intracellular accumulation of JHC 1-64-labeled NET and caused a parallel reduction in uptake capacity. Internalized NET strongly colocalized with the “long loop” recycling marker Rab11, whereas less overlap was seen with the “short loop” recycling marker Rab4 and the late endosomal marker Rab7. Moreover, mitigating Rab11 function by overexpression of dominant negative Rab11 impaired NET function. Sorting of NET to the Rab11 recycling compartment was further supported by confocal imaging and reversible biotinylation experiments in transfected differentiated CATH.a cells. In contrast to NET, the dopamine transporter displayed markedly less constitutive internalization and limited sorting to the Rab11 recycling compartment in the differentiated CATH.a cells. Exchange of domains between the two homologous transporters revealed that this difference was determined by non-conserved structural elements in the intracellular N terminus. We conclude that NET displays a distinct trafficking itinerary characterized by continuous shuffling between the plasma membrane and the Rab11 recycling compartment and that the functional integrity of the Rab11 compartment is critical for maintaining proper presynaptic NET function. PMID:26786096

  9. Prejunctional inhibition of norepinephrine release caused by acetylcholine in the human saphenous vein

    International Nuclear Information System (INIS)

    Rorie, D.K.; Rusch, N.J.; Shepherd, J.T.; Vanhoutte, P.M.; Tyce, G.M.

    1981-01-01

    We performed experiments to determine whether or not acetylcholine exerts a prejunctional inhibitory effect on adrenergic neurotransmission in the human blood vessel wall. Rings of human greater saphenous veins were prepared 2 to 15 hours after death and mounted for isometric tension recording in organ chambers filled with Krebs-Ringer solution. Acetylcholine depressed contractile responses to electric activation of the sympathetic nerve endings significantly more than those to exogenous norepinephrine; the relaxations caused by the cholinergic transmitter were antagonized by atropine. Helical strips were incubated with [/sub 3/H]norepinephrine and mounted for superfusion. Electric stimulation augmented the fractional release of labeled norepinephrine. Acetylcholine caused a depression of the evoked /sub 3/H release which was antagonized by atropine but not by hexamethonium. These experiments demonstrate that, as in animal cutaneous veins, there are prejunctional inhibitory muscarinic receptors on the adrenergic nerve endings in the human saphenous vein. By contrast, the human vein also contains postjunctional inhibitory muscarinic receptors

  10. Development of norepinephrine transporter reuptake inhibition assays using SK-N-BE(2C cells

    Directory of Open Access Journals (Sweden)

    Ann M. Decker

    2018-05-01

    Full Text Available This report describes efforts to develop and validate novel norepinephrine transporter reuptake inhibition assays using human neuroblastoma SK-N-BE(2C cells in 24-well format. Before conducting the assays, the SK-N-BE(2C cells were first evaluated for their ability to uptake [3H]norepinephrine and were shown to have a saturable uptake with a KM value of 416 nM. Using this determined KM value, reuptake inhibition assays were then conducted with a variety of ligands including antidepressants, as well as piperazine and phenyltropane derivatives. The results obtained with the SK-N-BE(2C cells indicate that this model system can detect a range of ligand potencies, which compare well with other established transporter assays. Our data suggest that SK-N-BE(2C cells have potential utility to serve as another model system to detect norepinephrine reuptake inhibition activity.

  11. Terlipressin versus norepinephrine in the treatment of hepatorenal syndrome: a systematic review and meta-analysis.

    Directory of Open Access Journals (Sweden)

    Antonio Paulo Nassar Junior

    Full Text Available BACKGROUND: Hepatorenal syndrome (HRS is a severe and progressive functional renal failure occurring in patients with cirrhosis and ascites. Terlipressin is recognized as an effective treatment of HRS, but it is expensive and not widely available. Norepinephrine could be an effective alternative. This systematic review and meta-analysis aimed to evaluate the efficacy and safety of norepinephrine compared to terlipressin in the management of HRS. METHODS: We searched the Medline, Embase, Scopus, CENTRAL, Lilacs and Scielo databases for randomized trials of norepinephrine and terlipressin in the treatment of HRS up to January 2014. Two reviewers collected data and assessed the outcomes and risk of bias. The primary outcome was the reversal of HRS. Secondary outcomes were mortality, recurrence of HRS and adverse events. RESULTS: Four studies comprising 154 patients were included. All trials were considered to be at overall high risk of bias. There was no difference in the reversal of HRS (RR = 0.97, 95% CI = 0.76 to 1.23, mortality at 30 days (RR = 0.89, 95% CI = 0.68 to 1.17 and recurrence of HRS (RR = 0.72; 95% CI = 0.36 to 1.45 between norepinephrine and terlipressin. Adverse events were less common with norepinephrine (RR = 0.36, 95% CI = 0.15 to 0.83. CONCLUSIONS: Norepinephrine seems to be an attractive alternative to terlipressin in the treatment of HRS and is associated with less adverse events. However, these findings are based on data extracted from only four small studies.

  12. Whole body clearance of norepinephrine. The significance of arterial sampling and of surgical stress

    DEFF Research Database (Denmark)

    Hilsted, J; Christensen, N J; Madsbad, S

    1983-01-01

    The whole body clearance of norepinephrine (NE) was measured in seven patients pre- and postoperatively. L[(3)H]NE was infused intravenously for 90 min and steady-state concentrations of L[(3)H]NE were measured at 75 and 90 min in both arterial and peripheral venous blood. Preoperatively, in the ......The whole body clearance of norepinephrine (NE) was measured in seven patients pre- and postoperatively. L[(3)H]NE was infused intravenously for 90 min and steady-state concentrations of L[(3)H]NE were measured at 75 and 90 min in both arterial and peripheral venous blood. Preoperatively...

  13. Molecular mechanisms of synaptic remodeling in alcoholism.

    Science.gov (United States)

    Kyzar, Evan J; Pandey, Subhash C

    2015-08-05

    Alcohol use and alcohol addiction represent dysfunctional brain circuits resulting from neuroadaptive changes during protracted alcohol exposure and its withdrawal. Alcohol exerts a potent effect on synaptic plasticity and dendritic spine formation in specific brain regions, providing a neuroanatomical substrate for the pathophysiology of alcoholism. Epigenetics has recently emerged as a critical regulator of gene expression and synaptic plasticity-related events in the brain. Alcohol exposure and withdrawal induce changes in crucial epigenetic processes in the emotional brain circuitry (amygdala) that may be relevant to the negative affective state defined as the "dark side" of addiction. Here, we review the literature concerning synaptic plasticity and epigenetics, with a particular focus on molecular events related to dendritic remodeling during alcohol abuse and alcoholism. Targeting epigenetic processes that modulate synaptic plasticity may yield novel treatments for alcoholism. Published by Elsevier Ireland Ltd.

  14. Time dependent changes in myocardial norepinephrine concentration and adrenergic receptor density following X-irradiation of the rat heart

    NARCIS (Netherlands)

    Franken, N. A.; van der Laarse, A.; Bosker, F. J.; Reynart, I. W.; van Ravels, F. J.; Strootman, E.; Wondergem, J.

    1992-01-01

    The hearts of 9 to 12-weeks-old Sprague-Dawley rats were locally irradiated with a single dose of 20 Gy. The effects on myocardial norepinephrine concentrations and on alpha-adrenergic and beta-adrenergic receptor densities was examined up to 16 months post-treatment. Myocardial norepinephrine

  15. Lateral regulation of synaptic transmission by astrocytes.

    Science.gov (United States)

    Covelo, A; Araque, A

    2016-05-26

    Fifteen years ago the concept of the "tripartite synapse" was proposed to conceptualize the functional view that astrocytes are integral elements of synapses. The signaling exchange between astrocytes and neurons within the tripartite synapse results in the synaptic regulation of synaptic transmission and plasticity through an autocrine form of communication. However, recent evidence indicates that the astrocyte synaptic regulation is not restricted to the active tripartite synapse but can be manifested through astrocyte signaling at synapses relatively distant from active synapses, a process termed lateral astrocyte synaptic regulation. This phenomenon resembles the classical heterosynaptic modulation but is mechanistically different because it involves astrocytes and its properties critically depend on the morphological and functional features of astrocytes. Therefore, the functional concept of the tripartite synapse as a fundamental unit must be expanded to include the interaction between tripartite synapses. Through lateral synaptic regulation, astrocytes serve as an active processing bridge for synaptic interaction and crosstalk between synapses with no direct neuronal connectivity, supporting the idea that neural network function results from the coordinated activity of astrocytes and neurons. Copyright © 2015 IBRO. Published by Elsevier Ltd. All rights reserved.

  16. α2-Adrenergic regulation of galanin and norepinephrine release from canine pancreas

    NARCIS (Netherlands)

    Scheurink, Anton J.W.; Mundinger, Thomas O.; Dunning, Beth E.; Veith, Richard C.; Taborsky, Jr.

    1992-01-01

    We found previously that electrical stimulation of the mixed autonomic pancreatic nerves (MPNS) in anesthesized dogs elicits marked and rapid increases of pancreatic output of both norepinephrine (NE) and galanin, and on that basis hypothesized a role for galanin as a sympathetic cotransmitter in

  17. The conversion of dopamine to epinephrine and nor-epinephrine is ...

    African Journals Online (AJOL)

    Tyrosine is a conditionally non-essential large neutral amino acid and the precursor of the neurotransmitters dopamine, nor-epinephrine and epinephrine. Ante-mortem stress experienced by an animal may be influenced by amino acids that provide substrates for neurotransmitter synthesis. The Nguni type cattle showed ...

  18. Effects of surgical stress and insulin on cardiovascular function and norepinephrine kinetics

    DEFF Research Database (Denmark)

    Christensen, N J; Hilsted, J; Hegedüs, Laszlo

    1984-01-01

    In resting supine subjects the whole-body clearance of norepinephrine (NE) based on arterial and venous sampling averaged 1.4 and 2.5 liters/min, respectively (P less than 0.02). The difference in clearance values was due to a peripheral uptake of NE averaging 45%. The calculation of plasma NE...

  19. Fluctuating Estrogen and Progesterone Receptor Expression in Brainstem Norepinephrine Neurons through the Rat Estrous Cycle

    NARCIS (Netherlands)

    Haywood, S.A.; Simonian, S.X.; Beek, van der E.M.; Bicknell, R.J.; Herbison, A.E.

    1999-01-01

    Norepinephrine (NE) neurons within the nucleus tractus solitarii (NTS; A2 neurons) and ventrolateral medulla (A1 neurons) represent gonadal steroid-dependent components of several neural networks regulating reproduction. Previous studies have shown that both A1 and A2 neurons express estrogen

  20. Effects of norepinephrine on tissue perfusion in a sheep model of intra-abdominal hypertension

    NARCIS (Netherlands)

    Ferrara, Gonzalo; Kanoore Edul, Vanina S.; Caminos Eguillor, Juan F.; Martins, Enrique; Canullán, Carlos; Canales, Héctor S.; Ince, Can; Estenssoro, Elisa; Dubin, Arnaldo

    2015-01-01

    The aim of the study was to describe the effects of intra-abdominal hypertension (IAH) on regional and microcirculatory intestinal blood flow, renal blood flow, and urine output, as well as their response to increases in blood pressure induced by norepinephrine. This was a pilot, controlled study,

  1. Increasing arterial blood pressure with norepinephrine does not improve microcirculatory blood flow: a prospective study

    NARCIS (Netherlands)

    Dubin, Arnaldo; Pozo, Mario O.; Casabella, Christian A.; Palizas, Fernando; Murias, Gaston; Moseinco, Miriam C.; Kanoore Edul, Vanina S.; Estenssoro, Elisa; Ince, Can

    2009-01-01

    Introduction Our goal was to assess the effects of titration of a norepinephrine infusion to increasing levels of mean arterial pressure (MAP) on sublingual microcirculation. Methods Twenty septic shock patients were prospectively studied in two teaching intensive care units. The patients were

  2. Is cerebral oxygenation negatively affected by infusion of norepinephrine in healthy subjects?

    DEFF Research Database (Denmark)

    Brassard, P.; Seifert, T.; Secher, Niels H.

    2009-01-01

    BACKGROUND: Vasopressor agents are commonly used to increase mean arterial pressure (MAP) in order to secure a pressure gradient to perfuse vital organs. The influence of norepinephrine on cerebral oxygenation is not clear. The aim of this study was to evaluate the impact of the infusion of norep......BACKGROUND: Vasopressor agents are commonly used to increase mean arterial pressure (MAP) in order to secure a pressure gradient to perfuse vital organs. The influence of norepinephrine on cerebral oxygenation is not clear. The aim of this study was to evaluate the impact of the infusion...... of norepinephrine on cerebral oxygenation in healthy subjects. METHODS: Three doses of norepinephrine (0.05, 0.1, and 0.15 microg kg(-1) min(-1) for 20 min each) were infused in nine healthy subjects [six males; 26 (6) yr, mean (SD)]. MAP, cerebral oxygenation characterized by frontal lobe oxygenation (Sc(O2...... infused at 0.1 microg kg(-1) min(-1) [Sc(O2): 78 (75-94) to 69 (61-83)%; P

  3. Mechanism of palytoxin-induced [3H]norepinephrine release from a rat pheochromocytoma cell line

    International Nuclear Information System (INIS)

    Tatsumi, M.; Takahashi, M.; Ohizumi, Y.

    1984-01-01

    Palytoxin, isolated from the zoanthid Palytoha species, is one of the most potent marine toxins. Palytoxin caused a release of [ 3 H]norepinephrine from clonal rat pheochromocytoma cells in a concentration-dependent manner. This releasing action of palytoxin was markedly inhibited or abolished by Co 2+ or Ca 2+ -free medium, but was not modified by tetrodotoxin. The release of [ 3 H]norepinephrine induced by a low concentration of palytoxin was abolished in sodium-free medium and increased as the external Na+ concentrations were increased, but the release induced by a high concentration was unaffected by varying the concentration of external Na + . The release of [ 3 H]norepinephrine induced by both concentrations of palytoxin increased with increasing Ca 2+ concentrations. Palytoxin caused a concentration-dependent increase in 22 Na and 45 Ca influxes into pheochromocytoma cells. The palytoxin-induced 45 Ca influx was markedly inhibited by Co 2+ , whereas the palytoxin-induced 22 Na influx was not affected by tetrodotoxin. These results suggest that in pheochromocytoma cells the [ 3 H]norepinephrine release induced by lower concentrations of palytoxin is primarily brought about by increasing tetrodotoxin-insensitive Na + permeability across the cell membrane, whereas that induced by higher concentrations is mainly caused by a direct increase in Ca 2+ influx into them

  4. The norepinephrine transporter gene is a candidate gene for panic disorder

    DEFF Research Database (Denmark)

    Buttenschøn, Henriette Nørmølle; Kristensen, A S; Buch, H N

    2011-01-01

    Panic disorder (PD) is an anxiety disorder characterized by recurrent panic attacks with a lifetime prevalence of 4.7%. Genetic factors are known to contribute to the development of the disorder. Several lines of evidence point towards a major role of the norepinephrine system in the pathogenesis...

  5. Toward heterogeneity in feedforward network with synaptic delays based on FitzHugh-Nagumo model

    Science.gov (United States)

    Qin, Ying-Mei; Men, Cong; Zhao, Jia; Han, Chun-Xiao; Che, Yan-Qiu

    2018-01-01

    We focus on the role of heterogeneity on the propagation of firing patterns in feedforward network (FFN). Effects of heterogeneities both in parameters of neuronal excitability and synaptic delays are investigated systematically. Neuronal heterogeneity is found to modulate firing rates and spiking regularity by changing the excitability of the network. Synaptic delays are strongly related with desynchronized and synchronized firing patterns of the FFN, which indicate that synaptic delays may play a significant role in bridging rate coding and temporal coding. Furthermore, quasi-coherence resonance (quasi-CR) phenomenon is observed in the parameter domain of connection probability and delay-heterogeneity. All these phenomena above enable a detailed characterization of neuronal heterogeneity in FFN, which may play an indispensable role in reproducing the important properties of in vivo experiments.

  6. Reversing the outcome of synapse elimination at developing neuromuscular junctions in vivo: evidence for synaptic competition and its mechanism.

    Directory of Open Access Journals (Sweden)

    Stephen G Turney

    Full Text Available During mammalian development, neuromuscular junctions and some other postsynaptic cells transition from multiple- to single-innervation as synaptic sites are exchanged between different axons. It is unclear whether one axon invades synaptic sites to drive off other inputs or alternatively axons expand their territory in response to sites vacated by other axons. Here we show that soon-to-be-eliminated axons rapidly reverse fate and grow to occupy vacant sites at a neuromuscular junction after laser removal of a stronger input. This reversal supports the idea that axons take over sites that were previously vacated. Indeed, during normal development we observed withdrawal followed by takeover. The stimulus for axon growth is not postsynaptic cell inactivity because axons grow into unoccupied sites even when target cells are functionally innervated. These results demonstrate competition at the synaptic level and enable us to provide a conceptual framework for understanding this form of synaptic plasticity.

  7. Reversing the outcome of synapse elimination at developing neuromuscular junctions in vivo: evidence for synaptic competition and its mechanism.

    Science.gov (United States)

    Turney, Stephen G; Lichtman, Jeff W

    2012-01-01

    During mammalian development, neuromuscular junctions and some other postsynaptic cells transition from multiple- to single-innervation as synaptic sites are exchanged between different axons. It is unclear whether one axon invades synaptic sites to drive off other inputs or alternatively axons expand their territory in response to sites vacated by other axons. Here we show that soon-to-be-eliminated axons rapidly reverse fate and grow to occupy vacant sites at a neuromuscular junction after laser removal of a stronger input. This reversal supports the idea that axons take over sites that were previously vacated. Indeed, during normal development we observed withdrawal followed by takeover. The stimulus for axon growth is not postsynaptic cell inactivity because axons grow into unoccupied sites even when target cells are functionally innervated. These results demonstrate competition at the synaptic level and enable us to provide a conceptual framework for understanding this form of synaptic plasticity.

  8. Diacylglycerol kinases in the coordination of synaptic plasticity

    Directory of Open Access Journals (Sweden)

    Dongwon Lee

    2016-08-01

    Full Text Available Synaptic plasticity is activity-dependent modification of the efficacy of synaptic transmission. Although detailed mechanisms underlying synaptic plasticity are diverse and vary at different types of synapses, diacylglycerol (DAG-associated signaling has been considered as an important regulator of many forms of synaptic plasticity, including long-term potentiation (LTP and long-term depression (LTD. Recent evidence indicate that DAG kinases (DGKs, which phosphorylate DAG to phosphatidic acid to terminate DAG signaling, are important regulators of LTP and LTD, as supported by the results from mice lacking specific DGK isoforms. This review will summarize these studies and discuss how specific DGK isoforms distinctly regulate different forms of synaptic plasticity at pre- and postsynaptic sites. In addition, we propose a general role of DGKs as coordinators of synaptic plasticity that make local synaptic environments more permissive for synaptic plasticity by regulating DAG concentration and interacting with other synaptic proteins.

  9. Metabolic Turnover of Synaptic Proteins: Kinetics, Interdependencies and Implications for Synaptic Maintenance

    Science.gov (United States)

    Cohen, Laurie D.; Zuchman, Rina; Sorokina, Oksana; Müller, Anke; Dieterich, Daniela C.; Armstrong, J. Douglas; Ziv, Tamar; Ziv, Noam E.

    2013-01-01

    Chemical synapses contain multitudes of proteins, which in common with all proteins, have finite lifetimes and therefore need to be continuously replaced. Given the huge numbers of synaptic connections typical neurons form, the demand to maintain the protein contents of these connections might be expected to place considerable metabolic demands on each neuron. Moreover, synaptic proteostasis might differ according to distance from global protein synthesis sites, the availability of distributed protein synthesis facilities, trafficking rates and synaptic protein dynamics. To date, the turnover kinetics of synaptic proteins have not been studied or analyzed systematically, and thus metabolic demands or the aforementioned relationships remain largely unknown. In the current study we used dynamic Stable Isotope Labeling with Amino acids in Cell culture (SILAC), mass spectrometry (MS), Fluorescent Non–Canonical Amino acid Tagging (FUNCAT), quantitative immunohistochemistry and bioinformatics to systematically measure the metabolic half-lives of hundreds of synaptic proteins, examine how these depend on their pre/postsynaptic affiliation or their association with particular molecular complexes, and assess the metabolic load of synaptic proteostasis. We found that nearly all synaptic proteins identified here exhibited half-lifetimes in the range of 2–5 days. Unexpectedly, metabolic turnover rates were not significantly different for presynaptic and postsynaptic proteins, or for proteins for which mRNAs are consistently found in dendrites. Some functionally or structurally related proteins exhibited very similar turnover rates, indicating that their biogenesis and degradation might be coupled, a possibility further supported by bioinformatics-based analyses. The relatively low turnover rates measured here (∼0.7% of synaptic protein content per hour) are in good agreement with imaging-based studies of synaptic protein trafficking, yet indicate that the metabolic load

  10. Electric Dipole Theory of Chemical Synaptic Transmission

    Science.gov (United States)

    Wei, Ling Y.

    1968-01-01

    In this paper we propose that chemicals such as acetylcholine are electric dipoles which when oriented and arranged in a large array could produce an electric field strong enough to drive positive ions over the junction barrier of the post-synaptic membrane and thus initiate excitation or produce depolarization. This theory is able to explain a great number of facts such as cleft size, synaptic delay, nonregeneration, subthreshold integration, facilitation with repetition, and the calcium and magnesium effects. It also shows why and how acetylcholine could act as excitatory or inhibitory transmitters under different circumstances. Our conclusion is that the nature of synaptic transmission is essentially electrical, be it mediated by electrical or chemical transmitters. PMID:4296121

  11. Astroglial Metabolic Networks Sustain Hippocampal Synaptic Transmission

    Science.gov (United States)

    Rouach, Nathalie; Koulakoff, Annette; Abudara, Veronica; Willecke, Klaus; Giaume, Christian

    2008-12-01

    Astrocytes provide metabolic substrates to neurons in an activity-dependent manner. However, the molecular mechanisms involved in this function, as well as its role in synaptic transmission, remain unclear. Here, we show that the gap-junction subunit proteins connexin 43 and 30 allow intercellular trafficking of glucose and its metabolites through astroglial networks. This trafficking is regulated by glutamatergic synaptic activity mediated by AMPA receptors. In the absence of extracellular glucose, the delivery of glucose or lactate to astrocytes sustains glutamatergic synaptic transmission and epileptiform activity only when they are connected by gap junctions. These results indicate that astroglial gap junctions provide an activity-dependent intercellular pathway for the delivery of energetic metabolites from blood vessels to distal neurons.

  12. Astroglial metabolic networks sustain hippocampal synaptic transmission.

    Science.gov (United States)

    Rouach, Nathalie; Koulakoff, Annette; Abudara, Veronica; Willecke, Klaus; Giaume, Christian

    2008-12-05

    Astrocytes provide metabolic substrates to neurons in an activity-dependent manner. However, the molecular mechanisms involved in this function, as well as its role in synaptic transmission, remain unclear. Here, we show that the gap-junction subunit proteins connexin 43 and 30 allow intercellular trafficking of glucose and its metabolites through astroglial networks. This trafficking is regulated by glutamatergic synaptic activity mediated by AMPA receptors. In the absence of extracellular glucose, the delivery of glucose or lactate to astrocytes sustains glutamatergic synaptic transmission and epileptiform activity only when they are connected by gap junctions. These results indicate that astroglial gap junctions provide an activity-dependent intercellular pathway for the delivery of energetic metabolites from blood vessels to distal neurons.

  13. Finite post synaptic potentials cause a fast neuronal response

    Directory of Open Access Journals (Sweden)

    Moritz eHelias

    2011-02-01

    Full Text Available A generic property of the communication between neurons is the exchange of pulsesat discrete time points, the action potentials. However, the prevalenttheory of spiking neuronal networks of integrate-and-fire model neuronsrelies on two assumptions: the superposition of many afferent synapticimpulses is approximated by Gaussian white noise, equivalent to avanishing magnitude of the synaptic impulses, and the transfer oftime varying signals by neurons is assessable by linearization. Goingbeyond both approximations, we find that in the presence of synapticimpulses the response to transient inputs differs qualitatively fromprevious predictions. It is instantaneous rather than exhibiting low-passcharacteristics, depends non-linearly on the amplitude of the impulse,is asymmetric for excitation and inhibition and is promoted by a characteristiclevel of synaptic background noise. These findings resolve contradictionsbetween the earlier theory and experimental observations. Here wereview the recent theoretical progress that enabled these insights.We explain why the membrane potential near threshold is sensitiveto properties of the afferent noise and show how this shapes the neuralresponse. A further extension of the theory to time evolution in discretesteps quantifies simulation artifacts and yields improved methodsto cross check results.

  14. Synaptic Vesicle Endocytosis in Different Model Systems

    Directory of Open Access Journals (Sweden)

    Quan Gan

    2018-06-01

    Full Text Available Neurotransmission in complex animals depends on a choir of functionally distinct synapses releasing neurotransmitters in a highly coordinated manner. During synaptic signaling, vesicles fuse with the plasma membrane to release their contents. The rate of vesicle fusion is high and can exceed the rate at which synaptic vesicles can be re-supplied by distant sources. Thus, local compensatory endocytosis is needed to replenish the synaptic vesicle pools. Over the last four decades, various experimental methods and model systems have been used to study the cellular and molecular mechanisms underlying synaptic vesicle cycle. Clathrin-mediated endocytosis is thought to be the predominant mechanism for synaptic vesicle recycling. However, recent studies suggest significant contribution from other modes of endocytosis, including fast compensatory endocytosis, activity-dependent bulk endocytosis, ultrafast endocytosis, as well as kiss-and-run. Currently, it is not clear whether a universal model of vesicle recycling exist for all types of synapses. It is possible that each synapse type employs a particular mode of endocytosis. Alternatively, multiple modes of endocytosis operate at the same synapse, and the synapse toggles between different modes depending on its activity level. Here we compile review and research articles based on well-characterized model systems: frog neuromuscular junctions, C. elegans neuromuscular junctions, Drosophila neuromuscular junctions, lamprey reticulospinal giant axons, goldfish retinal ribbon synapses, the calyx of Held, and rodent hippocampal synapses. We will compare these systems in terms of their known modes and kinetics of synaptic vesicle endocytosis, as well as the underlying molecular machineries. We will also provide the future development of this field.

  15. Stochastic Synapses Enable Efficient Brain-Inspired Learning Machines

    Science.gov (United States)

    Neftci, Emre O.; Pedroni, Bruno U.; Joshi, Siddharth; Al-Shedivat, Maruan; Cauwenberghs, Gert

    2016-01-01

    Recent studies have shown that synaptic unreliability is a robust and sufficient mechanism for inducing the stochasticity observed in cortex. Here, we introduce Synaptic Sampling Machines (S2Ms), a class of neural network models that uses synaptic stochasticity as a means to Monte Carlo sampling and unsupervised learning. Similar to the original formulation of Boltzmann machines, these models can be viewed as a stochastic counterpart of Hopfield networks, but where stochasticity is induced by a random mask over the connections. Synaptic stochasticity plays the dual role of an efficient mechanism for sampling, and a regularizer during learning akin to DropConnect. A local synaptic plasticity rule implementing an event-driven form of contrastive divergence enables the learning of generative models in an on-line fashion. S2Ms perform equally well using discrete-timed artificial units (as in Hopfield networks) or continuous-timed leaky integrate and fire neurons. The learned representations are remarkably sparse and robust to reductions in bit precision and synapse pruning: removal of more than 75% of the weakest connections followed by cursory re-learning causes a negligible performance loss on benchmark classification tasks. The spiking neuron-based S2Ms outperform existing spike-based unsupervised learners, while potentially offering substantial advantages in terms of power and complexity, and are thus promising models for on-line learning in brain-inspired hardware. PMID:27445650

  16. Impaired glucose-induced thermogenesis and arterial norepinephrine response persist after weight reduction in obese humans

    DEFF Research Database (Denmark)

    Astrup, A; Andersen, T; Christensen, N J

    1990-01-01

    A reduced thermic response and an impaired activation of the sympathetic nervous system (SNS) has been reported after oral glucose in human obesity. It is, however, not known whether the reduced SNS activity returns to normal along with weight reduction. The thermic effect of glucose was lower...... in eight obese patients than in matched control subjects (1.7% vs 9.2%, p less than 0.002). The increase in arterial norepinephrine after glucose was also blunted in the obese patients. After a 30-kg weight loss their glucose and lipid profiles were markedly improved but the thermic effect of glucose...... was still lower than that of the control subjects (4.2%, p less than 0.001). The glucose-induced arterial norepinephrine response remained diminished in the reduced obese patients whereas the changes in plasma epinephrine were similar in all three groups. The results suggest that a defective SNS may...

  17. Analytical Strategies for the Determination of Norepinephrine Reuptake Inhibitors in Pharmaceutical Formulations and Biological Fluids.

    Science.gov (United States)

    Saka, Cafer

    2016-01-01

    Norepinephrine reuptake inhibitors (NRIs) are a class of antidepressant drugs that act as reuptake inhibitors for the neurotransmitters norepinephrine and epinephrine. The present review provides an account of analytical methods published in recent years for the determination of NRI drugs. NRIs are atomoxetine, reboxetine, viloxazine and maprotiline. NRIs with less activity at other sites are mazindol, bupropion, tapentadol, and teniloxazine. This review focuses on the analytical methods including chromatographic, spectrophotometric, electroanalytical, and electrophoresis techniques for NRI analysis from pharmaceutical formulations and biological samples. Among all of the published methods, liquid chromatography with UV-vis or MS-MS detection is the most popular technique. The most the common sample preparation techniques in the analytical methods for NRIs include liquid-liquid extraction and solid-phase extraction. Besides the analytical methods for single components, some of the simultaneous determinations are also included in this review.

  18. Rapid adaptation of the stimulatory effect of CO2 on brain norepinephrine metabolism.

    Science.gov (United States)

    Stone, E A

    1983-12-01

    The present study examined the effects of exposure of rats to elevated environmental levels of CO2 on norepinephrine metabolism in the hypothalamus and other regions of the brain. In confirmation of previous findings by others CO2 at 10 or 15% was found to elevate both dopa accumulation after dopa decarboxylase inhibition and norepinephrine utilization after tyrosine hydroxylase inhibition. These effects however were found to be transient occurring only during the first 30 min of 2.5 h exposure. In this regard CO2 differs from another form of stress, restraint which produces a sustained 2.5 h increase of dopa accumulation and NE accumulation. Restraint was also more effective than CO2 in depleting endogenous stores of hypothalamic NE. The factor responsible for the adaptation of the catecholamine response to CO2 was not identified although it was shown not to be hypothermia and it was reversed by a 2 h CO2-free recovery period.

  19. Aggressive Behavior and Altered Amounts of Brain Serotonin and Norepinephrine in Mice Lacking MAOA

    Science.gov (United States)

    Cases, Olivier; Grimsby, Joseph; Gaspar, Patricia; Chen, Kevin; Pournin, Sandrine; Müller, Ulrike; Aguet, Michel; Babinet, Charles; Shih, Jean Chen; De Maeyer, Edward

    2010-01-01

    Deficiency in monoamine oxidase A (MAOA), an enzyme that degrades serotonin and norepinephrine, has recently been shown to be associated with aggressive behavior in men of a Dutch family. A line of transgenic mice was isolated in which transgene integration caused a deletion in the gene encoding MAOA, providing an animal model of MAOA deficiency. In pup brains, serotonin concentrations were increased up to ninefold, and serotonin-like immunoreactivity was present in catecholaminergic neurons. In pup and adult brains, norepinephrine concentrations were increased up to twofold, and cytoarchitectural changes were observed in the somatosensory cortex. Pup behavioral alterations, including trembling, difficulty in righting, and fearfulness were reversed by the serotonin synthesis inhibitor parachlorophenylalanine. Adults manifested a distinct behavioral syndrome, including enhanced aggression in males. PMID:7792602

  20. Flexible Proton-Gated Oxide Synaptic Transistors on Si Membrane.

    Science.gov (United States)

    Zhu, Li Qiang; Wan, Chang Jin; Gao, Ping Qi; Liu, Yang Hui; Xiao, Hui; Ye, Ji Chun; Wan, Qing

    2016-08-24

    Ion-conducting materials have received considerable attention for their applications in fuel cells, electrochemical devices, and sensors. Here, flexible indium zinc oxide (InZnO) synaptic transistors with multiple presynaptic inputs gated by proton-conducting phosphorosilicate glass-based electrolyte films are fabricated on ultrathin Si membranes. Transient characteristics of the proton gated InZnO synaptic transistors are investigated, indicating stable proton-gating behaviors. Short-term synaptic plasticities are mimicked on the proposed proton-gated synaptic transistors. Furthermore, synaptic integration regulations are mimicked on the proposed synaptic transistor networks. Spiking logic modulations are realized based on the transition between superlinear and sublinear synaptic integration. The multigates coupled flexible proton-gated oxide synaptic transistors may be interesting for neuroinspired platforms with sophisticated spatiotemporal information processing.

  1. Iatrogenic Takotsubo Cardiomyopathy Secondary to Norepinephrine by Continuous Infusion for Shock

    OpenAIRE

    Alfredo Vieira; Bárbara Batista; Tiago Tribolet de Abreu

    2018-01-01

    Takotsubo cardiomyopathy is a condition characterized by transient left ventricular systolic and diastolic dysfunction, with a possible direct causal role of catecholamine in its pathophysiology. We present a case of a woman with shock and adrenal insufficiency in whom Takotsubo cardiomyopathy developed after treatment with norepinephrine. This case confirms the direct causal role of catecholamine in the pathophysiology of Takotsubo cardiomyopathy. An 82-year-old woman presented with asthenia...

  2. Recent advances in the understanding of the interaction of antidepressant drugs with serotonin and norepinephrine transporters

    DEFF Research Database (Denmark)

    Andersen, Jacob; Kristensen, Anders Skov; Bang-Andersen, Benny

    2009-01-01

    The biogenic monoamine transporters are integral membrane proteins that perform active transport of extracellular dopamine, serotonin and norepinephrine into cells. These transporters are targets for therapeutic agents such as antidepressants, as well as addictive substances such as cocaine...... and amphetamine. Seminal advances in the understanding of the structure and function of this transporter family have recently been accomplished by structural studies of a bacterial transporter, as well as medicinal chemistry and pharmacological studies of mammalian transporters. This feature article focuses...

  3. Differential effects of phenylephrine and norepinephrine on peripheral tissue oxygenation during general anaesthesia : A randomised controlled trial

    NARCIS (Netherlands)

    Poterman, Marieke; Vos, Jaap Jan; Vereecke, Hugo E. M.; Struys, Michel M. R. F.; Vanoverschelde, Henk; Scheeren, Thomas W. L.; Kalmar, Alain F.

    BACKGROUND Phenylephrine and norepinephrine are two vasopressors commonly used to counteract anaesthesia-induced hypotension. Their dissimilar working mechanisms may differentially affect the macro and microcirculation, and ultimately tissue oxygenation. OBJECTIVES We investigated the differential

  4. Endoluminal norepinephrine inhibits smooth muscle activity of the pig pyeloureter by stimulation of beta-adrenoceptors without side effects

    DEFF Research Database (Denmark)

    Mortensen, Jens; Holst, Uffe; Jacobsen, Jørn Skibsted

    2008-01-01

    of pyeloureter and to reveal possible side effects on cardiovascular and renal functions. Renal pelvis was perfused, while pelvic pressure, cardiovascular and renal functional parameters were recorded. In group A, a pelvic pressure increase was examined during pressure flow studies with norepinephrine solutions......It has been demonstrated in pigs that endoluminal administration of norepinephrine reduces the increase in renal pelvic pressure during perfusion. The purposes were to describe concentration-response relationship and receptor mechanism of the effect of norepinephrine on muscle function...... a renal pelvis pressure increase to perfusion in a dose-related way without side effects. Endoluminal norepinephrine is safe in pigs and may be useful under endoscopy of the pyeloureter....

  5. Opioid withdrawal for 4 days prevents synaptic depression induced by low dose of morphine or naloxone in rat hippocampal CA1 area in vivo.

    Science.gov (United States)

    Dong, Zhifang; Han, Huili; Cao, Jun; Xu, Lin

    2010-02-01

    The formation of memory is believed to depend on experience- or activity-dependent synaptic plasticity, which is exquisitely sensitive to psychological stress since inescapable stress impairs long-term potentiation (LTP) but facilitates long-term depression (LTD). Our recent studies demonstrated that 4 days of opioid withdrawal enables maximal extents of both hippocampal LTP and drug-reinforced behavior; while elevated-platform stress enables these phenomena at 18 h of opioid withdrawal. Here, we examined the effects of low dose of morphine (0.5 mg kg(-1), i.p.) or the opioid receptor antagonist naloxone (1 mg kg(-1), i.p.) on synaptic efficacy in the hippocampal CA1 region of anesthetized rats. A form of synaptic depression was induced by low dose of morphine or naloxone in rats after 18 h but not 4 days of opioid withdrawal. This synaptic depression was dependent on both N-methyl-D-aspartate receptor and synaptic activity, similar to the hippocampal long-term depression induced by low frequency stimulation. Elevated-platform stress given 2 h before experiment prevented the synaptic depression at 18 h of opioid withdrawal; in contrast, the glucocorticoid receptor (GR) antagonist RU38486 treatment (20 mg kg(-1), s.c., twice per day for first 3 days of withdrawal), or a high dose of morphine reexposure (15 mg kg(-1), s.c., 12 h before experiment), enabled the synaptic depression on 4 days of opioid withdrawal. This temporal shift of synaptic depression by stress or GR blockade supplements our previous findings of potentially correlated temporal shifts of LTP induction and drug-reinforced behavior during opioid withdrawal. Our results therefore support the idea that stress experience during opioid withdrawal may modify hippocampal synaptic plasticity and play important roles in drug-associated memory. (c) 2009 Wiley-Liss, Inc.

  6. Synaptic ribbon. Conveyor belt or safety belt?

    Science.gov (United States)

    Parsons, T D; Sterling, P

    2003-02-06

    The synaptic ribbon in neurons that release transmitter via graded potentials has been considered as a conveyor belt that actively moves vesicles toward their release sites. But evidence has accumulated to the contrary, and it now seems plausible that the ribbon serves instead as a safety belt to tether vesicles stably in mutual contact and thus facilitate multivesicular release by compound exocytosis.

  7. P2X Receptors and Synaptic Plasticity

    Czech Academy of Sciences Publication Activity Database

    Pankratov, Y.; Lalo, U.; Krishtal, A.; Verkhratsky, Alexei

    2009-01-01

    Roč. 158, č. 1 (2009), s. 137-148 ISSN 0306-4522 Institutional research plan: CEZ:AV0Z50390512 Keywords : ATP * P2X receptors * synaptic plasticity Subject RIV: FH - Neurology Impact factor: 3.292, year: 2009

  8. Synaptic plasticity and the warburg effect

    KAUST Repository

    Magistretti, Pierre J.

    2014-01-01

    Functional brain imaging studies show that in certain brain regions glucose utilization exceeds oxygen consumption, indicating the predominance of aerobic glycolysis. In this issue, Goyal et al. (2014) report that this metabolic profile is associated with an enrichment in the expression of genes involved in synaptic plasticity and remodeling processes. © 2014 Elsevier Inc.

  9. Neuronal cytoskeleton in synaptic plasticity and regeneration.

    Science.gov (United States)

    Gordon-Weeks, Phillip R; Fournier, Alyson E

    2014-04-01

    During development, dynamic changes in the axonal growth cone and dendrite are necessary for exploratory movements underlying initial axo-dendritic contact and ultimately the formation of a functional synapse. In the adult central nervous system, an impressive degree of plasticity is retained through morphological and molecular rearrangements in the pre- and post-synaptic compartments that underlie the strengthening or weakening of synaptic pathways. Plasticity is regulated by the interplay of permissive and inhibitory extracellular cues, which signal through receptors at the synapse to regulate the closure of critical periods of developmental plasticity as well as by acute changes in plasticity in response to experience and activity in the adult. The molecular underpinnings of synaptic plasticity are actively studied and it is clear that the cytoskeleton is a key substrate for many cues that affect plasticity. Many of the cues that restrict synaptic plasticity exhibit residual activity in the injured adult CNS and restrict regenerative growth by targeting the cytoskeleton. Here, we review some of the latest insights into how cytoskeletal remodeling affects neuronal plasticity and discuss how the cytoskeleton is being targeted in an effort to promote plasticity and repair following traumatic injury in the central nervous system. © 2013 International Society for Neurochemistry.

  10. Norepinephrine remains increased in the six-minute walking test after heart transplantation

    Directory of Open Access Journals (Sweden)

    Guilherme Veiga Guimarães

    2010-01-01

    Full Text Available OBJECTIVE: We sought to evaluate the neurohormonal activity in heart transplant recipients and compare it with that in heart failure patients and healthy subjects during rest and just after a 6-minute walking test. INTRODUCTION: Despite the improvements in quality of life and survival provided by heart transplantation, the neurohormonal profile is poorly described. METHODS: Twenty heart transplantation (18 men, 49±11 years and 8.5±3.3 years after transplantation, 11 heart failure (8 men, 43±10 years, and 7 healthy subjects (5 men 39±8 years were included in this study. Blood samples were collected immediately before and during the last minute of the exercise. RESULTS: During rest, patients' norepinephrine plasma level (659±225 pg/mL was higher in heart transplant recipients (463±167 pg/mL and heathy subjects (512±132, p<0.05. Heart transplant recipient's norepinephrine plasma level was not different than that of healthy subjects. Just after the 6-minute walking test, the heart transplant recipient's norepinephrine plasma level (1248±692 pg/mL was not different from that of heart failure patients (1174±653 pg/mL. Both these groups had a higher level than healthy subjects had (545±95 pg/mL, p<0.05. CONCLUSION: Neurohormonal activity remains increased after the 6-minute walking test after heart transplantation.

  11. Stimulatory effects of neuronally released norepinephrine on renin release in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Matsumura, Yasuo; Kawazoe, Shinka; Ichihara, Toshio; Shinyama, Hiroshi; Kageyama, Masaaki; Morimoto, Shiro (Osaka Univ. of Pharmaceutical Sciences (Japan))

    1988-10-01

    Extracellular high potassium inhibits renin release in vitro by increasing calcium concentrations in the juxtaglomerular cells. The authors found that the decreased response of renin release from rat kidney cortical slices in high potassium solution changed to a strikingly increased one in the presence of nifedipine at doses over 10{sup {minus}6} M. They then examined the stimulatory effect of extracellular high potassium in the presence of nifedipine on renin release. The enhancement of release was significantly suppressed either by propranolol or by metoprolol but not by prazosin. High potassium plus nifedipine-induced increase in renin release was markedly attenuated by renal denervation. The enhancing effect was not observed when the slices were incubated in calcium-free medium. Divalent cations such as Cd{sup 2+}, Co{sup 2+}, and Mn{sup 2+} blocked this enhancement in a concentration-dependent manner. High potassium elicited an increase in {sup 3}H efflux from the slices preloaded with ({sup 3}H)-norepinephrine. The increasing effect was not influenced by nifedipine but was abolished by the removal of extracellular calcium or by the addition of divalent cations. These observations suggest to us that the high potassium plus nifedipine-induced increase in renin release from the slices is mediated by norepinephrine derived from renal sympathetic nerves and that this neuronally released norepinephrine stimulates renin release via activation of {beta}-adrenoceptors.

  12. Pulmonary circulatory effects of norepinephrine in newborn infants with persistent pulmonary hypertension.

    Science.gov (United States)

    Tourneux, Pierre; Rakza, Thameur; Bouissou, Antoine; Krim, Gérard; Storme, Laurent

    2008-09-01

    To evaluate the respiratory and the pulmonary circulatory effects of norepinephrine in newborn infants with persistent pulmonary hypertension (PPHN)-induced cardiac dysfunction. Inclusion criteria were: 1) Newborn infants >35 weeks gestational age; 2) PPHN treated with inhaled nitric oxide; and 3) symptoms of circulatory failure despite adequate fluid resuscitation. Lung function and pulmonary hemodynamic variables assessed with Doppler echocardiography were recorded prospectively before and after starting norepinephrine. Eighteen newborns were included (gestational age: 37 +/- 3 weeks; birth weight: 2800 +/- 700 g). After starting norepinephrine, systemic pressure and left ventricular output increased respectively from 33 +/- 4 mm Hg to 49 +/- 4 mm Hg and from 172 +/- 79 mL/kg/min to 209+/-90 mL/kg/min (P ventilatory variables have not been changed, the post-ductal transcutaneous arterial oxygen saturation increased from 89% +/- 1% to 95% +/- 4%, whereas the oxygen need decreased from 51% +/- 24% to 41% +/- 20% (P newborn infants with PPHN through a decrease in pulmonary/systemic artery pressure ratio and improved cardiac performance.

  13. Synaptic remodeling, synaptic growth and the storage of long-term memory in Aplysia.

    Science.gov (United States)

    Bailey, Craig H; Kandel, Eric R

    2008-01-01

    Synaptic remodeling and synaptic growth accompany various forms of long-term memory. Storage of the long-term memory for sensitization of the gill-withdrawal reflex in Aplysia has been extensively studied in this respect and is associated with the growth of new synapses by the sensory neurons onto their postsynaptic target neurons. Recent time-lapse imaging studies of living sensory-to-motor neuron synapses in culture have monitored both functional and structural changes simultaneously so as to follow remodeling and growth at the same specific synaptic connections continuously over time and to examine the functional contribution of these learning-related structural changes to the different time-dependent phases of memory storage. Insights provided by these studies suggest the synaptic differentiation and growth induced by learning in the mature nervous system are highly dynamic and often rapid processes that can recruit both molecules and mechanisms used for de novo synapse formation during development.

  14. Synaptic Plasticity, Dementia and Alzheimer Disease.

    Science.gov (United States)

    Skaper, Stephen D; Facci, Laura; Zusso, Morena; Giusti, Pietro

    2017-01-01

    Neuroplasticity is not only shaped by learning and memory but is also a mediator of responses to neuron attrition and injury (compensatory plasticity). As an ongoing process it reacts to neuronal cell activity and injury, death, and genesis, which encompasses the modulation of structural and functional processes of axons, dendrites, and synapses. The range of structural elements that comprise plasticity includes long-term potentiation (a cellular correlate of learning and memory), synaptic efficacy and remodelling, synaptogenesis, axonal sprouting and dendritic remodelling, and neurogenesis and recruitment. Degenerative diseases of the human brain continue to pose one of biomedicine's most intractable problems. Research on human neurodegeneration is now moving from descriptive to mechanistic analyses. At the same time, it is increasing apparently that morphological lesions traditionally used by neuropathologists to confirm post-mortem clinical diagnosis might furnish us with an experimentally tractable handle to understand causative pathways. Consider the aging-dependent neurodegenerative disorder Alzheimer's disease (AD) which is characterised at the neuropathological level by deposits of insoluble amyloid β-peptide (Aβ) in extracellular plaques and aggregated tau protein, which is found largely in the intracellular neurofibrillary tangles. We now appreciate that mild cognitive impairment in early AD may be due to synaptic dysfunction caused by accumulation of non-fibrillar, oligomeric Aβ, occurring well in advance of evident widespread synaptic loss and neurodegeneration. Soluble Aβ oligomers can adversely affect synaptic structure and plasticity at extremely low concentrations, although the molecular substrates by which synaptic memory mechanisms are disrupted remain to be fully elucidated. The dendritic spine constitutes a primary locus of excitatory synaptic transmission in the mammalian central nervous system. These structures protruding from dendritic

  15. Poly(norepinephrine)-coated open tubular column for the separation of proteins and recombination human erythropoietin by capillary electrochromatography.

    Science.gov (United States)

    Xiao, Xue; Zhang, Yamin; Wu, Jia; Jia, Li

    2017-12-01

    Recombinant human erythropoietin is an important therapeutic protein with high economic interest due to the benefits provided by its clinical use for the treatment of anemias associated with chronic renal failure and chemotherapy. In this work, a poly(norepinephrine)-coated open tubular column was successfully prepared based on the self-polymerization of norepinephrine under mild alkaline condition, the favorable film forming and easy adhesive properties of poly(norepinephrine). The poly(norepinephrine) coating was characterized by scanning electron microscopy and measurement of the electro-osmotic flow. The thickness of the coating was about 431 nm. The electrochromatographic performance of the poly(norepinephrine)-coated open tubular column was evaluated by separation of proteins. Some basic and acidic proteins including two variants of bovine serum albumin and two variants of β-lactoglobulin achieved separation in the poly(norepinephrine)-coated open tubular column. More importantly, the column demonstrated separation ability for the glycoforms of recombinant human erythropoietin. In addition, the column demonstrated good repeatability with the run-to-run, day-to-day, and column-to-column relative standard deviations of migration times of proteins less than 3.40%. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Fluid loading and norepinephrine infusion mask the left ventricular preload decrease induced by pleural effusion.

    Science.gov (United States)

    Wemmelund, Kristian Borup; Ringgård, Viktor Kromann; Vistisen, Simon Tilma; Hyldebrandt, Janus Adler; Sloth, Erik; Juhl-Olsen, Peter

    2017-09-11

    Pleural effusion (PLE) may lead to low blood pressure and reduced cardiac output. Low blood pressure and reduced cardiac output are often treated with fluid loading and vasopressors. This study aimed to determine the impact of fluid loading and norepinephrine infusion on physiologic determinants of cardiac function obtained by ultrasonography during PLE. In this randomised, blinded, controlled laboratory study, 30 piglets (21.9 ± 1.3 kg) had bilateral PLE (75 mL/kg) induced. Subsequently, the piglets were randomised to intervention as follows: fluid loading (80 mL/kg/h for 1.5 h, n = 12), norepinephrine infusion (0.01, 0.03, 0.05, 0.1, 0.2 and 0.3 μg/kg/min (15 min each, n = 12)) or control (n = 6). Main outcome was left ventricular preload measured as left ventricular end-diastolic area. Secondary endpoints included contractility and afterload as well as global measures of circulation. All endpoints were assessed with echocardiography and invasive pressure-flow measurements. PLE decreased left ventricular end-diastolic area, mean arterial pressure and cardiac output (p values  0.05) to baseline. Left ventricular contractility increased with norepinephrine infusion (p = 0.002), but was not affected by fluid loading (p = 0.903). Afterload increased in both active groups (p values > 0.001). Overall, inferior vena cava distensibility remained unchanged during intervention (p values ≥ 0.085). Evacuation of PLE caused numerical increases in left ventricular end-diastolic area, but only significantly so in controls (p = 0.006). PLE significantly reduced left ventricular preload. Both fluid and norepinephrine treatment reverted this effect and normalised global haemodynamic parameters. Inferior vena cava distensibility remained unchanged. The haemodynamic significance of PLE may be underestimated during fluid or norepinephrine administration, potentially masking the presence of PLE.

  17. Evaluation of radioiodinated (2S,{alpha}S)-2-({alpha}-(2-iodophenoxy)benzyl)morpholine as a radioligand for imaging of norepinephrine transporter in the heart

    Energy Technology Data Exchange (ETDEWEB)

    Kiyono, Yasushi [Biomedical Imaging Research Center, University of Fukui, Fukui 910-1193 (Japan); Radioisotopes Research Laboratory, Kyoto University Hospital, Faculty of Medicine, Kyoto University, Kyoto 606-8507 (Japan)], E-mail: ykiyono@u-fukui.ac.jp; Sugita, Taku [Department of Pathofunctional Bioanalysis, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501 (Japan); Ueda, Masashi [Radioisotopes Research Laboratory, Kyoto University Hospital, Faculty of Medicine, Kyoto University, Kyoto 606-8507 (Japan); Kawashima, Hidekazu [Department of Nuclear Medicine and Diagnostic Imaging, Graduate School of Medicine, Kyoto University, Kyoto 606-8507 (Japan); Kanegawa, Naoki; Kuge, Yuji [Department of Pathofunctional Bioanalysis, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501 (Japan); Fujibayashi, Yasuhisa [Biomedical Imaging Research Center, University of Fukui, Fukui 910-1193 (Japan); Saji, Hideo [Department of Pathofunctional Bioanalysis, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501 (Japan)

    2008-02-15

    Introduction: The norepinephrine transporter (NET) is located presynaptically on noradrenergic nerve terminals and plays a critical role in the regulation of the synaptic norepinephrine (NE) concentration via the reuptake of NE. Changes in NET have been recently reported in several cardiac failures. Therefore, a NET-specific radioligand is useful for in vivo assessment of changes in NET density in various cardiac disorders. Recently, we developed a radioiodinated reboxetine analogue, (2S,{alpha}S)-2-({alpha}-(2-iodophenoxy)benzyl)morpholine ((S,S)-IPBM), for NET imaging. In the current study, we assessed the applicability of radioiodinated (S,S)-IPBM to NET imaging in the heart. Methods: The NET affinity and selectivity were measured from the ability to displace specific [{sup 3}H]nisoxetine and (S,S)-[{sup 125}I]IPBM binding to rat heart membrane, respectively. To evaluate the distribution of (S,S)-[{sup 125}I]IPBM in vivo, biodistribution experiment was performed in rats. With the use of several monoamine transporter binding agents, pharmacological blocking experiments were performed in rats. Results: In vitro binding assays showed that the affinity of (S,S)-IPBM to NET was similar to those of the well-known NET-specific binding agents, nisoxetine and desipramine. Furthermore, (S,S)-[{sup 125}I]IPBM binding was inhibited by nisoxetine and desipramine, but not by dopamine or serotonin transporter binding agents. These data indicated that (S,S)-IPBM had high affinity and selectivity for NET in vitro. Biodistribution studies in rats showed rapid and high uptake of (S,S)-[{sup 125}I]IPBM by the heart and rapid clearance from the blood. The heart-to-blood ratio was 31.9 at 180 min after the injection. The administration of nisoxetine and desipramine decreased (S,S)-[{sup 125}I]IPBM accumulation in the heart, but injection of fluoxetine and GBR12909 had little influence. Conclusions: Radioiodinated (S,S)-IPBM is a potential radioligand for NET imaging in the heart.

  18. The Structure of Neurexin 1[alpha] Reveals Features Promoting a Role as Synaptic Organizer

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Fang; Venugopal, Vandavasi; Murray, Beverly; Rudenko, Gabby (Michigan)

    2014-10-02

    {alpha}-Neurexins are essential synaptic adhesion molecules implicated in autism spectrum disorder and schizophrenia. The {alpha}-neurexin extracellular domain consists of six LNS domains interspersed by three EGF-like repeats and interacts with many different proteins in the synaptic cleft. To understand how {alpha}-neurexins might function as synaptic organizers, we solved the structure of the neurexin 1{alpha} extracellular domain (n1{alpha}) to 2.65 {angstrom}. The L-shaped molecule can be divided into a flexible repeat I (LNS1-EGF-A-LNS2), a rigid horseshoe-shaped repeat II (LNS3-EGF-B-LNS4) with structural similarity to so-called reelin repeats, and an extended repeat III (LNS5-EGF-B-LNS6) with controlled flexibility. A 2.95 {angstrom} structure of n1{alpha} carrying splice insert SS3 in LNS4 reveals that SS3 protrudes as a loop and does not alter the rigid arrangement of repeat II. The global architecture imposed by conserved structural features enables {alpha}-neurexins to recruit and organize proteins in distinct and variable ways, influenced by splicing, thereby promoting synaptic function.

  19. Influence of Synaptic Depression on Memory Storage Capacity

    Science.gov (United States)

    Otsubo, Yosuke; Nagata, Kenji; Oizumi, Masafumi; Okada, Masato

    2011-08-01

    Synaptic efficacy between neurons is known to change within a short time scale dynamically. Neurophysiological experiments show that high-frequency presynaptic inputs decrease synaptic efficacy between neurons. This phenomenon is called synaptic depression, a short term synaptic plasticity. Many researchers have investigated how the synaptic depression affects the memory storage capacity. However, the noise has not been taken into consideration in their analysis. By introducing ``temperature'', which controls the level of the noise, into an update rule of neurons, we investigate the effects of synaptic depression on the memory storage capacity in the presence of the noise. We analytically compute the storage capacity by using a statistical mechanics technique called Self Consistent Signal to Noise Analysis (SCSNA). We find that the synaptic depression decreases the storage capacity in the case of finite temperature in contrast to the case of the low temperature limit, where the storage capacity does not change.

  20. Ultrafast Synaptic Events in a Chalcogenide Memristor

    Science.gov (United States)

    Li, Yi; Zhong, Yingpeng; Xu, Lei; Zhang, Jinjian; Xu, Xiaohua; Sun, Huajun; Miao, Xiangshui

    2013-04-01

    Compact and power-efficient plastic electronic synapses are of fundamental importance to overcoming the bottlenecks of developing a neuromorphic chip. Memristor is a strong contender among the various electronic synapses in existence today. However, the speeds of synaptic events are relatively slow in most attempts at emulating synapses due to the material-related mechanism. Here we revealed the intrinsic memristance of stoichiometric crystalline Ge2Sb2Te5 that originates from the charge trapping and releasing by the defects. The device resistance states, representing synaptic weights, were precisely modulated by 30 ns potentiating/depressing electrical pulses. We demonstrated four spike-timing-dependent plasticity (STDP) forms by applying programmed pre- and postsynaptic spiking pulse pairs in different time windows ranging from 50 ms down to 500 ns, the latter of which is 105 times faster than the speed of STDP in human brain. This study provides new opportunities for building ultrafast neuromorphic computing systems and surpassing Von Neumann architecture.

  1. Synaptic theory of Replicator-like melioration

    Directory of Open Access Journals (Sweden)

    Yonatan Loewenstein

    2010-06-01

    Full Text Available According to the theory of Melioration, organisms in repeated choice settings shift their choice preference in favor of the alternative that provides the highest return. The goal of this paper is to explain how this learning behavior can emerge from microscopic changes in the efficacies of synapses, in the context of two-alternative repeated-choice experiment. I consider a large family of synaptic plasticity rules in which changes in synaptic efficacies are driven by the covariance between reward and neural activity. I construct a general framework that predicts the learning dynamics of any decision-making neural network that implements this synaptic plasticity rule and show that melioration naturally emerges in such networks. Moreover, the resultant learning dynamics follows the Replicator equation which is commonly used to phenomenologically describe changes in behavior in operant conditioning experiments. Several examples demonstrate how the learning rate of the network is affected by its properties and by the specifics of the plasticity rule. These results help bridge the gap between cellular physiology and learning behavior.

  2. Bio-mimicked atomic-layer-deposited iron oxide-based memristor with synaptic potentiation and depression functions

    Science.gov (United States)

    Wan, Xiang; Gao, Fei; Lian, Xiaojuan; Ji, Xincun; Hu, Ertao; He, Lin; Tong, Yi; Guo, Yufeng

    2018-06-01

    In this study, an iron oxide (FeO x )-based memristor was investigated for the realization of artificial synapses. An FeO x resistive switching layer was prepared by self-limiting atomic layer deposition (ALD). The movement of oxygen vacancies enabled the device to have history-dependent synaptic functions, which was further demonstrated by device modeling and simulation. Analog synaptic potentiation/depression in conductance was emulated by applying consecutive voltage pulses in the simulation. Our results suggest that the ALD FeO x -based memristor can be used as the basic building block for neural networks, neuromorphic systems, and brain-inspired computers.

  3. Dynamic Control of Synaptic Adhesion and Organizing Molecules in Synaptic Plasticity

    Energy Technology Data Exchange (ETDEWEB)

    Rudenko, Gabby (Texas-MED)

    2017-01-01

    Synapses play a critical role in establishing and maintaining neural circuits, permitting targeted information transfer throughout the brain. A large portfolio of synaptic adhesion/organizing molecules (SAMs) exists in the mammalian brain involved in synapse development and maintenance. SAMs bind protein partners, formingtrans-complexes spanning the synaptic cleft orcis-complexes attached to the same synaptic membrane. SAMs play key roles in cell adhesion and in organizing protein interaction networks; they can also provide mechanisms of recognition, generate scaffolds onto which partners can dock, and likely take part in signaling processes as well. SAMs are regulated through a portfolio of different mechanisms that affect their protein levels, precise localization, stability, and the availability of their partners at synapses. Interaction of SAMs with their partners can further be strengthened or weakened through alternative splicing, competing protein partners, ectodomain shedding, or astrocytically secreted factors. Given that numerous SAMs appear altered by synaptic activity, in vivo, these molecules may be used to dynamically scale up or scale down synaptic communication. Many SAMs, including neurexins, neuroligins, cadherins, and contactins, are now implicated in neuropsychiatric and neurodevelopmental diseases, such as autism spectrum disorder, schizophrenia, and bipolar disorder and studying their molecular mechanisms holds promise for developing novel therapeutics.

  4. Characterization and extraction of the synaptic apposition surface for synaptic geometry analysis

    Science.gov (United States)

    Morales, Juan; Rodríguez, Angel; Rodríguez, José-Rodrigo; DeFelipe, Javier; Merchán-Pérez, Angel

    2013-01-01

    Geometrical features of chemical synapses are relevant to their function. Two critical components of the synaptic junction are the active zone (AZ) and the postsynaptic density (PSD), as they are related to the probability of synaptic release and the number of postsynaptic receptors, respectively. Morphological studies of these structures are greatly facilitated by the use of recent electron microscopy techniques, such as combined focused ion beam milling and scanning electron microscopy (FIB/SEM), and software tools that permit reconstruction of large numbers of synapses in three dimensions. Since the AZ and the PSD are in close apposition and have a similar surface area, they can be represented by a single surface—the synaptic apposition surface (SAS). We have developed an efficient computational technique to automatically extract this surface from synaptic junctions that have previously been three-dimensionally reconstructed from actual tissue samples imaged by automated FIB/SEM. Given its relationship with the release probability and the number of postsynaptic receptors, the surface area of the SAS is a functionally relevant measure of the size of a synapse that can complement other geometrical features like the volume of the reconstructed synaptic junction, the equivalent ellipsoid size and the Feret's diameter. PMID:23847474

  5. Negative feedback regulation of Homer 1a on norepinephrine-dependent cardiac hypertrophy

    Energy Technology Data Exchange (ETDEWEB)

    Chiarello, Carmelina; Bortoloso, Elena; Carpi, Andrea; Furlan, Sandra; Volpe, Pompeo, E-mail: pompeo.volpe@unipd.it

    2013-07-15

    Homers are scaffolding proteins that modulate diverse cell functions being able to assemble signalling complexes. In this study, the presence, sub-cellular distribution and function of Homer 1 was investigated. Homer 1a and Homer 1b/c are constitutively expressed in cardiac muscle of both mouse and rat and in HL-1 cells, a cardiac cell line. As judged by confocal immunofluorescence microscopy, Homer 1a displays sarcomeric and peri-nuclear localization. In cardiomyocytes and cultured HL-1 cells, the hypertrophic agonist norepinephrine (NE) induces α{sub 1}-adrenergic specific Homer 1a over-expression, with a two-to-three-fold increase within 1 h, and no up-regulation of Homer 1b/c, as judged by Western blot and qPCR. In HL-1 cells, plasmid-driven over-expression of Homer 1a partially antagonizes activation of ERK phosphorylation and ANF up-regulation, two well-established, early markers of hypertrophy. At the morphometric level, NE-induced increase of cell size is likewise and partially counteracted by exogenous Homer 1a. Under the same experimental conditions, Homer 1b/c does not have any effect on ANF up-regulation nor on cell hypertrophy. Thus, Homer 1a up-regulation is associated to early stages of cardiac hypertrophy and appears to play a negative feedback regulation on molecular transducers of hypertrophy. -- Highlights: • Homer 1a is constitutively expressed in cardiac tissue. • In HL-1 cells, norepinephrine activates signaling pathways leading to hypertrophy. • Homer 1a up-regulation is an early event of norepinephrine-induced hypertrophy. • Homer 1a plays a negative feedback regulation modulating pathological hypertrophy. • Over-expression of Homer 1a per se does not induce hypertrophy.

  6. Negative feedback regulation of Homer 1a on norepinephrine-dependent cardiac hypertrophy

    International Nuclear Information System (INIS)

    Chiarello, Carmelina; Bortoloso, Elena; Carpi, Andrea; Furlan, Sandra; Volpe, Pompeo

    2013-01-01

    Homers are scaffolding proteins that modulate diverse cell functions being able to assemble signalling complexes. In this study, the presence, sub-cellular distribution and function of Homer 1 was investigated. Homer 1a and Homer 1b/c are constitutively expressed in cardiac muscle of both mouse and rat and in HL-1 cells, a cardiac cell line. As judged by confocal immunofluorescence microscopy, Homer 1a displays sarcomeric and peri-nuclear localization. In cardiomyocytes and cultured HL-1 cells, the hypertrophic agonist norepinephrine (NE) induces α 1 -adrenergic specific Homer 1a over-expression, with a two-to-three-fold increase within 1 h, and no up-regulation of Homer 1b/c, as judged by Western blot and qPCR. In HL-1 cells, plasmid-driven over-expression of Homer 1a partially antagonizes activation of ERK phosphorylation and ANF up-regulation, two well-established, early markers of hypertrophy. At the morphometric level, NE-induced increase of cell size is likewise and partially counteracted by exogenous Homer 1a. Under the same experimental conditions, Homer 1b/c does not have any effect on ANF up-regulation nor on cell hypertrophy. Thus, Homer 1a up-regulation is associated to early stages of cardiac hypertrophy and appears to play a negative feedback regulation on molecular transducers of hypertrophy. -- Highlights: • Homer 1a is constitutively expressed in cardiac tissue. • In HL-1 cells, norepinephrine activates signaling pathways leading to hypertrophy. • Homer 1a up-regulation is an early event of norepinephrine-induced hypertrophy. • Homer 1a plays a negative feedback regulation modulating pathological hypertrophy. • Over-expression of Homer 1a per se does not induce hypertrophy

  7. Combined Norepinephrine / Serotonergic Reuptake Inhibition: Effects on Maternal Behavior, Aggression and Oxytocin in the Rat

    Directory of Open Access Journals (Sweden)

    Elizabeth Thomas Cox

    2011-06-01

    Full Text Available BACKGROUND: Few systematic studies exist on the effects of chronic reuptake of monoamine neurotransmitter systems during pregnancy on the regulation of maternal behavior, although many drugs act primarily through one or more of these systems. Previous studies examining fluoxetine and amfonelic acid treatment during gestation on subsequent maternal behavior in rodents indicated significant alterations in postpartum maternal care, aggression and oxytocin levels. In this study, we extended our studies to include chronic gestational treatment with desipramine or amitriptyline to examine differential effects of reuptake inhibition of norepinephrine and combined noradrenergic and serotonergic systems on maternal behavior, aggression, and oxytocin system changes. METHODS: Pregnant Sprague-Dawley rats were treated throughout gestation with saline or one of three doses of either desipramine, which has a high affinity for the norepinephrine monoamine transporter, or amitriptyline, an agent with high affinity for both the norepinephrine and serotonin monoamine transporters. Maternal behavior and postpartum aggression were assessed on postpartum days one and six respectively. Oxytocin levels were measured in relevant brain regions on postpartum day seven. Predictions were that amitriptyline would decrease maternal behavior and increase aggression relative to desipramine, particularly at higher doses. Amygdaloidal oxytocin was expected to decrease with increased aggression. RESULTS: Amitriptyline and desiprimine differentially reduced maternal behavior, and at higher doses reduced aggressive behavior. Hippocampal oxytocin levels were lower after treatment with either drug but were not correlated with specific behavioral effects. These results, in combination with previous findings following gestational treatment with other selective neurotransmitter reuptake inhibitors, highlight the diverse effects of multiple monoamine systems thought to be involved in

  8. Muscle interstitial ATP and norepinephrine concentrations in the human leg during exercise and ATP infusion

    DEFF Research Database (Denmark)

    Mortensen, Stefan P.; Gonzalez-Alonso, Jose; Nielsen, Jens Jung

    2009-01-01

    ATP and NE concentrations to gain insight into the interstitial and intravascular mechanisms by which ATP causes muscle vasodilation and sympatholysis. Leg hemodynamics and muscle interstitial nucleotide and norepinephrine (NE) concentrations were measured during: 1) femoral arterial ATP infusion (0......, respectively (Pcontracting muscle (Pmuscle, whereas interstitial NE concentrations increased similarly in both active...... and inactive muscles. These results suggest that the vasodilatory and sympatholytic effects of intraluminal ATP are mainly mediated via endothelial prinergic receptors. Intraluminal ATP and muscle contractions appear to modulate sympathetic nerve activity by inhibiting the effect of NE rather than blunting its...

  9. Reserpine-induced Reduction in Norepinephrine Transporter Function Requires Catecholamine Storage Vesicles

    OpenAIRE

    Mandela, Prashant; Chandley, Michelle; Xu, Yao-Yu; Zhu, Meng-Yang; Ordway, Gregory A.

    2010-01-01

    Treatment of rats with reserpine, an inhibitor of the vesicular monoamine transporter (VMAT), depletes norepinephrine (NE) and regulates NE transporter (NET) expression. The present study examined the molecular mechanisms involved in regulation of the NET by reserpine using cultured cells. Exposure of rat PC12 cells to reserpine for a period as short as 5 min decreased [3H]NE uptake capacity, an effect characterized by a robust decrease in the Vmax of the transport of [3H]NE. As expected, res...

  10. Synthesis and biological evaluation of trans-3-phenyl-1-indanamines as potential norepinephrine transporter imaging agents

    International Nuclear Information System (INIS)

    McConathy, Jonathan; Owens, Michael J.; Kilts, Clinton D.; Malveaux, Eugene J.; Votaw, John R.; Nemeroff, Charles B.; Goodman, Mark M.

    2005-01-01

    The development of radioligands suitable for studying the central nervous system (CNS) norepinephrine transporter (NET) in vivo will provide important new tools for examining the pathophysiology and pharmacotherapy of a variety of neuropsychiatric disorders including major depression. Towards this end, a series of trans-3-phenyl-1-indanamine derivatives were prepared and evaluated in vitro. The biological properties of the most promising compound, [ 11 C]3-BrPA, were investigated in rat biodistribution and nonhuman primate PET studies. Despite high in vitro affinity for the human NET, the uptake of [ 11 C]3-BrPA in the brain and the heart was not displaceable with pharmacological doses of NET antagonists

  11. Consensus statement and research needs: the role of dopamine and norepinephrine in depression and antidepressant treatment.

    Science.gov (United States)

    Nutt, David J; Baldwin, David S; Clayton, Anita H; Elgie, Rodney; Lecrubier, Yves; Montejo, Angel L; Papakostas, George I; Souery, Daniel; Trivedi, Madhukar H; Tylee, Andre

    2006-01-01

    During a special session, the faculty identified several specific areas related to the role of dopamine and norepinephrine in depression and antidepressant treatment that either warrant the clinician's attention or are in need of more research. Areas of interest include fatigue and lethargy in depression, treatment strategies for treatment-resistant depression, the somatic presentation of depression, neurobiology of fatigue and its role in determining treatment, symptom rating scales, and sexual side effects. In addition, the faculty discussed the importance of patient psychoeducation and self-management as well as the ways in which disease models of depression affect treatment.

  12. Atomoxetine affects transcription/translation of the NMDA receptor and the norepinephrine transporter in the rat brain – an in vivo study

    Directory of Open Access Journals (Sweden)

    Udvardi PT

    2013-12-01

    Full Text Available Patrick T Udvardi,1,2 Karl J Föhr,3 Carolin Henes,1,2 Stefan Liebau,2 Jens Dreyhaupt,4 Tobias M Boeckers,2 Andrea G Ludolph11Department of Child and Adolescent Psychiatry and Psychotherapy, 2Institute of Anatomy and Cell Biology, 3Department of Anaesthesiology, 4Institute of Epidemiology and Medical Biometry, University of Ulm, Ulm, GermanyAbstract: Attention-deficit/hyperactivity disorder (ADHD is the most frequently diagnosed neurodevelopmental disorder. The norepinephrine transporter (NET inhibitor atomoxetine, the first nonstimulant drug licensed for ADHD treatment, also acts as an N-methyl-D-aspartate receptor (NMDAR antagonist. The compound's effects on gene expression and protein levels of NET and NMDAR subunits (1, 2A, and 2B are unknown. Therefore, adolescent Sprague Dawley rats were treated with atomoxetine (3 mg/kg, intraperitoneal injection [ip] or saline (0.9%, ip for 21 consecutive days on postnatal days (PND 21–41. In humans, atomoxetine's earliest clinical therapeutic effects emerge after 2–3 weeks. Material from prefrontal cortex, striatum (STR, mesencephalon (MES, and hippocampus (HC was analyzed either directly after treatment (PND 42 or 2 months after termination of treatment (PND 101 to assess the compound's long-term effects. In rat brains analyzed immediately after treatment, protein analysis exhibited decreased levels of the NET in HC, and NMDAR subunit 2B in both STR and HC; the transcript levels were unaltered. In rat brains probed 2 months after final atomoxetine exposure, messenger RNA analysis also revealed significantly reduced levels of genes coding for NMDAR subunits in MES and STR. NMDAR protein levels were reduced in STR and HC. Furthermore, the levels of two SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor proteins, synaptophysin and synaptosomal-associated protein 25, were also significantly altered in both treatment groups. This in vivo study detected atomoxetine's effects

  13. Atomoxetine affects transcription/translation of the NMDA receptor and the norepinephrine transporter in the rat brain – an in vivo study

    Science.gov (United States)

    Udvardi, Patrick T; Föhr, Karl J; Henes, Carolin; Liebau, Stefan; Dreyhaupt, Jens; Boeckers, Tobias M; Ludolph, Andrea G

    2013-01-01

    Attention-deficit/hyperactivity disorder (ADHD) is the most frequently diagnosed neurodevelopmental disorder. The norepinephrine transporter (NET) inhibitor atomoxetine, the first nonstimulant drug licensed for ADHD treatment, also acts as an N-methyl-D-aspartate receptor (NMDAR) antagonist. The compound’s effects on gene expression and protein levels of NET and NMDAR subunits (1, 2A, and 2B) are unknown. Therefore, adolescent Sprague Dawley rats were treated with atomoxetine (3 mg/kg, intraperitoneal injection [ip]) or saline (0.9%, ip) for 21 consecutive days on postnatal days (PND) 21–41. In humans, atomoxetine’s earliest clinical therapeutic effects emerge after 2–3 weeks. Material from prefrontal cortex, striatum (STR), mesencephalon (MES), and hippocampus (HC) was analyzed either directly after treatment (PND 42) or 2 months after termination of treatment (PND 101) to assess the compound’s long-term effects. In rat brains analyzed immediately after treatment, protein analysis exhibited decreased levels of the NET in HC, and NMDAR subunit 2B in both STR and HC; the transcript levels were unaltered. In rat brains probed 2 months after final atomoxetine exposure, messenger RNA analysis also revealed significantly reduced levels of genes coding for NMDAR subunits in MES and STR. NMDAR protein levels were reduced in STR and HC. Furthermore, the levels of two SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) proteins, synaptophysin and synaptosomal-associated protein 25, were also significantly altered in both treatment groups. This in vivo study detected atomoxetine’s effects beyond NET inhibition. Taken together, these data reveal that atomoxetine seems to decrease glutamatergic transmission in a brain region-specific manner. Long-term data show that the compound’s impact is not due to an acute pharmacological effect but lasts or even amplifies after a drug-free period of 2 months, leading to altered development of

  14. Synaptic control of local translation: the plot thickens with new characters.

    Science.gov (United States)

    Thomas, María Gabriela; Pascual, Malena Lucía; Maschi, Darío; Luchelli, Luciana; Boccaccio, Graciela Lidia

    2014-06-01

    The production of proteins from mRNAs localized at the synapse ultimately controls the strength of synaptic transmission, thereby affecting behavior and cognitive functions. The regulated transcription, processing, and transport of mRNAs provide dynamic control of the dendritic transcriptome, which includes thousands of messengers encoding multiple cellular functions. Translation is locally modulated by synaptic activity through a complex network of RNA-binding proteins (RBPs) and various types of non-coding RNAs (ncRNAs) including BC-RNAs, microRNAs, piwi-interacting RNAs, and small interference RNAs. The RBPs FMRP and CPEB play a well-established role in synaptic translation, and additional regulatory factors are emerging. The mRNA repressors Smaug, Nanos, and Pumilio define a novel pathway for local translational control that affects dendritic branching and spines in both flies and mammals. Recent findings support a role for processing bodies and related synaptic mRNA-silencing foci (SyAS-foci) in the modulation of synaptic plasticity and memory formation. The SyAS-foci respond to different stimuli with changes in their integrity thus enabling regulated mRNA release followed by translation. CPEB, Pumilio, TDP-43, and FUS/TLS form multimers through low-complexity regions related to prion domains or polyQ expansions. The oligomerization of these repressor RBPs is mechanistically linked to the aggregation of abnormal proteins commonly associated with neurodegeneration. Here, we summarize the current knowledge on how specificity in mRNA translation is achieved through the concerted action of multiple pathways that involve regulatory ncRNAs and RBPs, the modification of translation factors, and mRNA-silencing foci dynamics.

  15. Inferior Olive HCN1 Channels Coordinate Synaptic Integration and Complex Spike Timing

    Directory of Open Access Journals (Sweden)

    Derek L.F. Garden

    2018-02-01

    Full Text Available Cerebellar climbing-fiber-mediated complex spikes originate from neurons in the inferior olive (IO, are critical for motor coordination, and are central to theories of cerebellar learning. Hyperpolarization-activated cyclic-nucleotide-gated (HCN channels expressed by IO neurons have been considered as pacemaker currents important for oscillatory and resonant dynamics. Here, we demonstrate that in vitro, network actions of HCN1 channels enable bidirectional glutamatergic synaptic responses, while local actions of HCN1 channels determine the timing and waveform of synaptically driven action potentials. These roles are distinct from, and may complement, proposed pacemaker functions of HCN channels. We find that in behaving animals HCN1 channels reduce variability in the timing of cerebellar complex spikes, which serve as a readout of IO spiking. Our results suggest that spatially distributed actions of HCN1 channels enable the IO to implement network-wide rules for synaptic integration that modulate the timing of cerebellar climbing fiber signals.

  16. Mechanisms of glycine release, which build up synaptic and extrasynaptic glycine levels: the role of synaptic and non-synaptic glycine transporters.

    Science.gov (United States)

    Harsing, Laszlo G; Matyus, Peter

    2013-04-01

    Glycine is an amino acid neurotransmitter that is involved in both inhibitory and excitatory neurochemical transmission in the central nervous system. The role of glycine in excitatory neurotransmission is related to its coagonist action at glutamatergic N-methyl-D-aspartate receptors. The glycine levels in the synaptic cleft rise many times higher during synaptic activation assuring that glycine spills over into the extrasynaptic space. Another possible origin of extrasynaptic glycine is the efflux of glycine occurring from astrocytes associated with glutamatergic synapses. The release of glycine from neuronal or glial origins exhibits several differences compared to that of biogenic amines or other amino acid neurotransmitters. These differences appear in an external Ca(2+)- and temperature-dependent manner, conferring unique characteristics on glycine as a neurotransmitter. Glycine transporter type-1 at synapses may exhibit neural and glial forms and plays a role in controlling synaptic glycine levels and the spill over rate of glycine from the synaptic cleft into the extrasynaptic biophase. Non-synaptic glycine transporter type-1 regulates extrasynaptic glycine concentrations, either increasing or decreasing them depending on the reverse or normal mode operation of the carrier molecule. While we can, at best, only estimate synaptic glycine levels at rest and during synaptic activation, glycine concentrations are readily measurable via brain microdialysis technique applied in the extrasynaptic space. The non-synaptic N-methyl-D-aspartate receptor may obtain glycine for activation following its spill over from highly active synapses or from its release mediated by the reverse operation of non-synaptic glycine transporter-1. The sensitivity of non-synaptic N-methyl-D-aspartate receptors to glutamate and glycine is many times higher than that of synaptic N-methyl-D-aspartate receptors making the former type of receptor the primary target for drug action. Synaptic

  17. Synaptic Contacts Enhance Cell-to-Cell Tau Pathology Propagation

    Directory of Open Access Journals (Sweden)

    Sara Calafate

    2015-05-01

    Full Text Available Accumulation of insoluble Tau protein aggregates and stereotypical propagation of Tau pathology through the brain are common hallmarks of tauopathies, including Alzheimer’s disease (AD. Propagation of Tau pathology appears to occur along connected neurons, but whether synaptic contacts between neurons are facilitating propagation has not been demonstrated. Using quantitative in vitro models, we demonstrate that, in parallel to non-synaptic mechanisms, synapses, but not merely the close distance between the cells, enhance the propagation of Tau pathology between acceptor hippocampal neurons and Tau donor cells. Similarly, in an artificial neuronal network using microfluidic devices, synapses and synaptic activity are promoting neuronal Tau pathology propagation in parallel to the non-synaptic mechanisms. Our work indicates that the physical presence of synaptic contacts between neurons facilitate Tau pathology propagation. These findings can have implications for synaptic repair therapies, which may turn out to have adverse effects by promoting propagation of Tau pathology.

  18. Attractor neural networks with resource-efficient synaptic connectivity

    Science.gov (United States)

    Pehlevan, Cengiz; Sengupta, Anirvan

    Memories are thought to be stored in the attractor states of recurrent neural networks. Here we explore how resource constraints interplay with memory storage function to shape synaptic connectivity of attractor networks. We propose that given a set of memories, in the form of population activity patterns, the neural circuit choses a synaptic connectivity configuration that minimizes a resource usage cost. We argue that the total synaptic weight (l1-norm) in the network measures the resource cost because synaptic weight is correlated with synaptic volume, which is a limited resource, and is proportional to neurotransmitter release and post-synaptic current, both of which cost energy. Using numerical simulations and replica theory, we characterize optimal connectivity profiles in resource-efficient attractor networks. Our theory explains several experimental observations on cortical connectivity profiles, 1) connectivity is sparse, because synapses are costly, 2) bidirectional connections are overrepresented and 3) are stronger, because attractor states need strong recurrence.

  19. Lidocaine attenuates anisomycin-induced amnesia and release of norepinephrine in the amygdala

    Science.gov (United States)

    Sadowski, Renee N.; Canal, Clint E.; Gold, Paul E.

    2011-01-01

    When administered near the time of training, protein synthesis inhibitors such as anisomycin impair later memory. A common interpretation of these findings is that memory consolidation requires new protein synthesis initiated by training. However, recent findings support an alternative interpretation that abnormally large increases in neurotransmitter release after injections of anisomycin may be responsible for producing amnesia. In the present study, a local anesthetic was administered prior to anisomycin injections in an attempt to mitigate neurotransmitter actions and thereby attenuate the resulting amnesia. Rats received lidocaine and anisomycin injections into the amygdala 130 and 120 min, respectively, prior to inhibitory avoidance training. Memory tests 48 hr later revealed that lidocaine attenuated anisomycin-induced amnesia. In other rats, in vivo microdialysis was performed at the site of amygdala infusion of lidocaine and anisomycin. As seen previously, anisomycin injections produced large increases in release of norepinephrine in the amygdala. Lidocaine attenuated the anisomycin-induced increase in release of norepinephrine but did not reverse anisomycin inhibition of protein synthesis, as assessed by c-Fos immunohistochemistry. These findings are consistent with past evidence suggesting that anisomycin causes amnesia by initiating abnormal release of neurotransmitters in response to the inhibition of protein synthesis. PMID:21453778

  20. Increased norepinephrine release from dog pulmonary artery caused by nitrous oxide

    International Nuclear Information System (INIS)

    Rorie, D.K.; Tyce, G.M.; Sill, J.C.

    1986-01-01

    The effects of nitrous oxide on the release and metabolism of norepinephrine (NE) at neuroeffector junctions in dog pulmonary artery were examined. Helical strips of artery were incubated in Krebs-Ringer solution containing L-( 3 H)NE and mounted for superfusion. The arterial strips were studied in the presence of 95% oxygen-5% carbon dioxide, 70% nitrogen-30% oxygen, or 70% nitrous oxide-30% oxygen. During the 60 min of each experiment, five samples of superfusion fluid were collected for analysis and the effluxes of ( 3 H)NE and its radiolabeled metabolites were measured before and during electrical stimulation and during recovery from stimulation. ( 3 H)Norepinephrine was separated from its metabolites in the superfusate and in extracts of artery by column chromatography and quantitated by liquid scintillation spectrometry. Nitrous oxide significantly increased the fractional loss of total radioactivity and the amount of NE in the superfusate both during resting conditions and during stimulation. Nitrous oxide had no effect on the proportions of radioactivity among metabolites of NE in the superfusate or on the profile of NE metabolites remaining in the tissue after experimentation. These findings are consistent with increased NE release as a direct effect of nitrous oxide on nerve endings

  1. Atomoxetine, a norepinephrine reuptake inhibitor, reduces seizure-induced respiratory arrest.

    Science.gov (United States)

    Zhang, Honghai; Zhao, Haiting; Feng, Hua-Jun

    2017-08-01

    Sudden unexpected death in epilepsy (SUDEP) is a devastating epilepsy complication, and no effective preventive strategies are currently available for this fatal disorder. Clinical and animal studies of SUDEP demonstrate that seizure-induced respiratory arrest (S-IRA) is the primary event leading to death after generalized seizures in many cases. Enhancing brain levels of serotonin reduces S-IRA in animal models relevant to SUDEP, including the DBA/1 mouse. Given that serotonin in the brain plays an important role in modulating respiration and arousal, these findings suggest that deficits in respiration and/or arousal may contribute to S-IRA. It is well known that norepinephrine is an important neurotransmitter that modulates respiration and arousal in the brain as well. Therefore, we hypothesized that enhancing noradrenergic neurotransmission suppresses S-IRA. To test this hypothesis, we examined the effect of atomoxetine, a norepinephrine reuptake inhibitor (NRI), on S-IRA evoked by either acoustic stimulation or pentylenetetrazole in DBA/1 mice. We report the original observation that atomoxetine specifically suppresses S-IRA without altering the susceptibility to seizures evoked by acoustic stimulation, and atomoxetine also reduces S-IRA evoked by pentylenetetrazole in DBA/1 mice. Our data suggest that the noradrenergic signaling is importantly involved in S-IRA, and that atomoxetine, a medication widely used to treat attention deficit hyperactivity disorder (ADHD), is potentially useful to prevent SUDEP. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Inhibition of K+ permeability diminishes alpha 2-adrenoceptor mediated effects on norepinephrine release

    International Nuclear Information System (INIS)

    Zimanyi, I.; Folly, G.; Vizi, E.S.

    1988-01-01

    The effect of two different potassium channel blockers, 4-aminopyridine (4-AP) and quinine, on the alpha 2-adrenoceptor mediated modulation of norepinephrine (NE) release was investigated. Pairs of mouse vasa deferentia were loaded with 3 H-norepinephrine ( 3 H-NE), superfused continuously, and stimulated electrically. 4-AP (5.3 x 10(-4) M), and quinine (10(-5) M) enhanced the stimulation-evoked release of tritium significantly. The electrically induced release of radioactivity was reduced by alpha 2-adrenoceptor agonists (1-NE and xylazine) and enhanced by the alpha 2-adrenoceptor antagonist yohimbine. Both effects were affected markedly by 4-AP or quinine: the depressant action of 1-NA and xylazine was partially antagonized and the facilitatory effect of yohimbine was completely abolished during the blockade of the potassium channels. It is suggested that the blockade of the potassium permeability counteracts negative feedback modulation; therefore, it seems likely that the stimulation of alpha 2-adrenoceptors leads to an enhanced potassium permeability and hyperpolarization of varicose axon terminals

  3. Anxiety-induced plasma norepinephrine augmentation increases reactive oxygen species formation by monocytes in essential hypertension.

    Science.gov (United States)

    Yasunari, Kenichi; Matsui, Tokuzo; Maeda, Kensaku; Nakamura, Munehiro; Watanabe, Takanori; Kiriike, Nobuo

    2006-06-01

    An association between anxiety and depression and increased blood pressure (BP) and cardiovascular disease risk has not been firmly established. We examined the hypothesis that anxiety and depression lead to increased plasma catecholamines and to production of reactive oxygen species (ROS) by mononuclear cells (MNC) in hypertensive individuals. We also studied the role of BP in this effect. In Protocol 1, a cross-sectional study was performed in 146 hypertensive patients to evaluate whether anxiety and depression affect BP and ROS formation by MNC through increasing plasma catecholamines. In Protocol 2, a 6-month randomized controlled trial using a subtherapeutic dose of the alpha(1)-adrenergic receptor antagonist doxazosin (1 mg/day) versus placebo in 86 patients with essential hypertension was performed to determine whether the increase in ROS formation by MNC was independent of BP. In Protocol 1, a significant relationship was observed between the following: trait anxiety and plasma norepinephrine (r = 0.32, P anxiety may increase plasma norepinephrine and increase ROS formation by MNC independent of BP in hypertensive patients.

  4. Stress hormone epinephrine (adrenaline) and norepinephrine (noradrenaline) effects on the anaerobic bacteria.

    Science.gov (United States)

    Boyanova, Lyudmila

    2017-04-01

    Microbial endocrinology is a relatively new research area that already encompasses the anaerobes. Stress hormones, epinephrine and norepinephrine, can affect the growth of anaerobic bacteria such as Fusobacterium nucleatum, Prevotella spp., Porhyromonas spp., Tanerella forsythia and Propionibacterium acnes and can increase virulence gene expression, iron acquisition and many virulence factors of some anaerobic species such as Clostridium perfringens, Porphyromonas gingivalis and Brachyspira pilosicoli. Epinephrine and norepinephrine effects can lead to a growth increase or decrease, or no effect on the growth of the anaerobes. The effects are species-specific and perhaps strain-specific. Discrepancies in the results of some studies can be due to the different methods and media used, catecholamine concentrations, measurement techniques and the low number of strains tested. Biological effects of the stress hormones on the anaerobes may range from halitosis and a worsening of periodontal diseases to tissue damages and atherosclerotic plaque ruptures. Optimizations of the research methods and a detailed assessment of the catecholamine effects in conditions mimicking those in affected organs and tissues, as well as the effects on the quorum sensing and virulence of the anaerobes and the full spectrum of biological consequences of the effects are interesting topics for further evaluation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Defective Glycinergic Synaptic Transmission in Zebrafish Motility Mutants

    OpenAIRE

    Hirata, Hiromi; Carta, Eloisa; Yamanaka, Iori; Harvey, Robert J.; Kuwada, John Y.

    2010-01-01

    Glycine is a major inhibitory neurotransmitter in the spinal cord and brainstem. Recently, in vivo analysis of glycinergic synaptic transmission has been pursued in zebrafish using molecular genetics. An ENU mutagenesis screen identified two behavioral mutants that are defective in glycinergic synaptic transmission. Zebrafish bandoneon (beo) mutants have a defect in glrbb, one of the duplicated glycine receptor (GlyR) β subunit genes. These mutants exhibit a loss of glycinergic synaptic ...

  6. Statistical mechanics of attractor neural network models with synaptic depression

    International Nuclear Information System (INIS)

    Igarashi, Yasuhiko; Oizumi, Masafumi; Otsubo, Yosuke; Nagata, Kenji; Okada, Masato

    2009-01-01

    Synaptic depression is known to control gain for presynaptic inputs. Since cortical neurons receive thousands of presynaptic inputs, and their outputs are fed into thousands of other neurons, the synaptic depression should influence macroscopic properties of neural networks. We employ simple neural network models to explore the macroscopic effects of synaptic depression. Systems with the synaptic depression cannot be analyzed due to asymmetry of connections with the conventional equilibrium statistical-mechanical approach. Thus, we first propose a microscopic dynamical mean field theory. Next, we derive macroscopic steady state equations and discuss the stabilities of steady states for various types of neural network models.

  7. Experimental Implementation of a Biometric Laser Synaptic Sensor

    Directory of Open Access Journals (Sweden)

    Alexander N. Pisarchik

    2013-12-01

    Full Text Available We fabricate a biometric laser fiber synaptic sensor to transmit information from one neuron cell to the other by an optical way. The optical synapse is constructed on the base of an erbium-doped fiber laser, whose pumped diode current is driven by a pre-synaptic FitzHugh–Nagumo electronic neuron, and the laser output controls a post-synaptic FitzHugh–Nagumo electronic neuron. The implemented laser synapse displays very rich dynamics, including fixed points, periodic orbits with different frequency-locking ratios and chaos. These regimes can be beneficial for efficient biorobotics, where behavioral flexibility subserved by synaptic connectivity is a challenge.

  8. A pivotal role of GSK-3 in synaptic plasticity

    Directory of Open Access Journals (Sweden)

    Clarrisa A Bradley

    2012-02-01

    Full Text Available Glycogen synthase kinase-3 (GSK-3 has many cellular functions. Recent evidence suggests that it plays a key role in certain types of synaptic plasticity, in particular a form of long-term depression (LTD that is induced by the synaptic activation of N-methyl-D-aspartate (NMDA receptors. In the present article we summarise what is currently known concerning the roles of GSK-3 in synaptic plasticity at both glutamatergic and GABAergic synapses. We summarise its role in cognition and speculate on how alterations in the synaptic functioning of GSK-3 may be a major factor in certain neurodegenerative disorders.

  9. proBDNF Negatively Regulates Neuronal Remodeling, Synaptic Transmission, and Synaptic Plasticity in Hippocampus

    Directory of Open Access Journals (Sweden)

    Jianmin Yang

    2014-05-01

    Full Text Available Experience-dependent plasticity shapes postnatal development of neural circuits, but the mechanisms that refine dendritic arbors, remodel spines, and impair synaptic activity are poorly understood. Mature brain-derived neurotrophic factor (BDNF modulates neuronal morphology and synaptic plasticity, including long-term potentiation (LTP via TrkB activation. BDNF is initially translated as proBDNF, which binds p75NTR. In vitro, recombinant proBDNF modulates neuronal structure and alters hippocampal long-term plasticity, but the actions of endogenously expressed proBDNF are unclear. Therefore, we generated a cleavage-resistant probdnf knockin mouse. Our results demonstrate that proBDNF negatively regulates hippocampal dendritic complexity and spine density through p75NTR. Hippocampal slices from probdnf mice exhibit depressed synaptic transmission, impaired LTP, and enhanced long-term depression (LTD in area CA1. These results suggest that proBDNF acts in vivo as a biologically active factor that regulates hippocampal structure, synaptic transmission, and plasticity, effects that are distinct from those of mature BDNF.

  10. Synaptic Democracy and Vesicular Transport in Axons

    Science.gov (United States)

    Bressloff, Paul C.; Levien, Ethan

    2015-04-01

    Synaptic democracy concerns the general problem of how regions of an axon or dendrite far from the cell body (soma) of a neuron can play an effective role in neuronal function. For example, stimulated synapses far from the soma are unlikely to influence the firing of a neuron unless some sort of active dendritic processing occurs. Analogously, the motor-driven transport of newly synthesized proteins from the soma to presynaptic targets along the axon tends to favor the delivery of resources to proximal synapses. Both of these phenomena reflect fundamental limitations of transport processes based on a localized source. In this Letter, we show that a more democratic distribution of proteins along an axon can be achieved by making the transport process less efficient. This involves two components: bidirectional or "stop-and-go" motor transport (which can be modeled in terms of advection-diffusion), and reversible interactions between motor-cargo complexes and synaptic targets. Both of these features have recently been observed experimentally. Our model suggests that, just as in human societies, there needs to be a balance between "efficiency" and "equality".

  11. Aerobic glycolysis during brain activation: adrenergic regulation and influence of norepinephrine on astrocytic metabolism.

    Science.gov (United States)

    Dienel, Gerald A; Cruz, Nancy F

    2016-07-01

    Aerobic glycolysis occurs during brain activation and is characterized by preferential up-regulation of glucose utilization compared with oxygen consumption even though oxygen level and delivery are adequate. Aerobic glycolysis is a widespread phenomenon that underlies energetics of diverse brain activities, such as alerting, sensory processing, cognition, memory, and pathophysiological conditions, but specific cellular functions fulfilled by aerobic glycolysis are poorly understood. Evaluation of evidence derived from different disciplines reveals that aerobic glycolysis is a complex, regulated phenomenon that is prevented by propranolol, a non-specific β-adrenoceptor antagonist. The metabolic pathways that contribute to excess utilization of glucose compared with oxygen include glycolysis, the pentose phosphate shunt pathway, the malate-aspartate shuttle, and astrocytic glycogen turnover. Increased lactate production by unidentified cells, and lactate dispersal from activated cells and lactate release from the brain, both facilitated by astrocytes, are major factors underlying aerobic glycolysis in subjects with low blood lactate levels. Astrocyte-neuron lactate shuttling with local oxidation is minor. Blockade of aerobic glycolysis by propranolol implicates adrenergic regulatory processes including adrenal release of epinephrine, signaling to brain via the vagus nerve, and increased norepinephrine release from the locus coeruleus. Norepinephrine has a powerful influence on astrocytic metabolism and glycogen turnover that can stimulate carbohydrate utilization more than oxygen consumption, whereas β-receptor blockade 're-balances' the stoichiometry of oxygen-glucose or -carbohydrate metabolism by suppressing glucose and glycogen utilization more than oxygen consumption. This conceptual framework may be helpful for design of future studies to elucidate functional roles of preferential non-oxidative glucose utilization and glycogen turnover during brain

  12. Mass spectrometric measurements of norepinephrine synthesis in man from infusion of stable isotope-labelled L-threo-3,4-dihydroxyphenylserine

    International Nuclear Information System (INIS)

    Suzuki, T.; Sakoda, S.; Ueji, M.; Kishimoto, S.

    1985-01-01

    The kinetics of stable isotope-labelled L-threo-3,4-dihydroxyphenylserine (L-threo-DOPS), an immediate precursor of (-)-norepinephrine, was studied to investigate the pharmacologic mechanism of its therapeutic effect on orthostatic hypotension in familial amyloid polyneuropathy (FAP) and on akinesia and freezing in parkinsonism. [ 13 C,D]-L-threo-DOPS was synthesized, and 100 mg of the compound was infused for 2 h into two normal subjects, two FAP patients and two patients with the degenerative diseases of the central nervous system. Labelled and endogenous norepinephrine in urine and plasma was assayed simultaneously by gas chromatography/mass spectrometry. The results indicate that the increase in norepinephrine in biological fluids after administration of L-threo-DOPS is attributable mostly to norepinephrine derived from L-threo-DOPS, not to pre-formed endogenous norepinephrine released by L-threo-DOPS

  13. A presynaptic role for PKA in synaptic tagging and memory.

    Science.gov (United States)

    Park, Alan Jung; Havekes, Robbert; Choi, Jennifer Hk; Luczak, Vince; Nie, Ting; Huang, Ted; Abel, Ted

    2014-10-01

    Protein kinase A (PKA) and other signaling molecules are spatially restricted within neurons by A-kinase anchoring proteins (AKAPs). Although studies on compartmentalized PKA signaling have focused on postsynaptic mechanisms, presynaptically anchored PKA may contribute to synaptic plasticity and memory because PKA also regulates presynaptic transmitter release. Here, we examine this issue using genetic and pharmacological application of Ht31, a PKA anchoring disrupting peptide. At the hippocampal Schaffer collateral CA3-CA1 synapse, Ht31 treatment elicits a rapid decay of synaptic responses to repetitive stimuli, indicating a fast depletion of the readily releasable pool of synaptic vesicles. The interaction between PKA and proteins involved in producing this pool of synaptic vesicles is supported by biochemical assays showing that synaptic vesicle protein 2 (SV2), Rim1, and SNAP25 are components of a complex that interacts with cAMP. Moreover, acute treatment with Ht31 reduces the levels of SV2. Finally, experiments with transgenic mouse lines, which express Ht31 in excitatory neurons at the Schaffer collateral CA3-CA1 synapse, highlight a requirement for presynaptically anchored PKA in pathway-specific synaptic tagging and long-term contextual fear memory. These results suggest that a presynaptically compartmentalized PKA is critical for synaptic plasticity and memory by regulating the readily releasable pool of synaptic vesicles. Copyright © 2014 Elsevier Inc. All rights reserved.

  14. Glutamatergic synaptic plasticity in the mesocorticolimbic system in addiction

    Directory of Open Access Journals (Sweden)

    Aile evan Huijstee

    2015-01-01

    Full Text Available Addictive drugs remodel the brain’s reward circuitry, the mesocorticolimbic dopamine system, by inducing widespread adaptations of glutamatergic synapses. This drug-induced synaptic plasticity is thought to contribute to both the development and the persistence of addiction. This review highlights the synaptic modifications that are induced by in vivo exposure to addictive drugs and describes how these drug-induced synaptic changes may contribute to the different components of addictive behaviour, such as compulsive drug use despite negative consequences and relapse. Initially, exposure to an addictive drug induces synaptic changes in the ventral tegmental area (VTA. This drug-induced synaptic potentiation in the VTA subsequently triggers synaptic changes in downstream areas of the mesocorticolimbic system, such as the nucleus accumbens (NAc and the prefrontal cortex (PFC, with further drug exposure. These glutamatergic synaptic alterations are then thought to mediate many of the behavioural symptoms that characterize addiction. The later stages of glutamatergic synaptic plasticity in the NAc and in particular in the PFC play a role in maintaining addiction and drive relapse to drug-taking induced by drug-associated cues. Remodelling of PFC glutamatergic circuits can persist into adulthood, causing a lasting vulnerability to relapse. We will discuss how these neurobiological changes produced by drugs of abuse may provide novel targets for potential treatment strategies for addiction.

  15. Phosphodiesterase Inhibition to Target the Synaptic Dysfunction in Alzheimer's Disease

    Science.gov (United States)

    Bales, Kelly R.; Plath, Niels; Svenstrup, Niels; Menniti, Frank S.

    Alzheimer's Disease (AD) is a disease of synaptic dysfunction that ultimately proceeds to neuronal death. There is a wealth of evidence that indicates the final common mediator of this neurotoxic process is the formation and actions on synaptotoxic b-amyloid (Aβ). The premise in this review is that synaptic dysfunction may also be an initiating factor in for AD and promote synaptotoxic Aβ formation. This latter hypothesis is consistent with the fact that the most common risk factors for AD, apolipoprotein E (ApoE) allele status, age, education, and fitness, encompass suboptimal synaptic function. Thus, the synaptic dysfunction in AD may be both cause and effect, and remediating synaptic dysfunction in AD may have acute effects on the symptoms present at the initiation of therapy and also slow disease progression. The cyclic nucleotide (cAMP and cGMP) signaling systems are intimately involved in the regulation of synaptic homeostasis. The phosphodiesterases (PDEs) are a superfamily of enzymes that critically regulate spatial and temporal aspects of cyclic nucleotide signaling through metabolic inactivation of cAMP and cGMP. Thus, targeting the PDEs to promote improved synaptic function, or 'synaptic resilience', may be an effective and facile approach to new symptomatic and disease modifying therapies for AD. There continues to be a significant drug discovery effort aimed at discovering PDE inhibitors to treat a variety of neuropsychiatric disorders. Here we review the current status of those efforts as they relate to potential new therapies for AD.

  16. Synaptogenic proteins and synaptic organizers: "many hands make light work".

    Science.gov (United States)

    Brose, Nils

    2009-03-12

    Synaptogenesis is thought to be mediated by cell adhesion proteins, which induce the initial contact between an axon and its target cell and subsequently recruit and organize the presynaptic and postsynaptic protein machinery required for synaptic transmission. A new study by Linhoff and colleagues in this issue of Neuron identifies adhesion proteins of the LRRTM family as novel synaptic organizers.

  17. Synaptic Tagging, Evaluation of Memories, and the Distal Reward Problem

    Science.gov (United States)

    Papper, Marc; Kempter, Richard; Leibold, Christian

    2011-01-01

    Long-term synaptic plasticity exhibits distinct phases. The synaptic tagging hypothesis suggests an early phase in which synapses are prepared, or "tagged," for protein capture, and a late phase in which those proteins are integrated into the synapses to achieve memory consolidation. The synapse specificity of the tags is consistent with…

  18. Glutamatergic synaptic plasticity in the mesocorticolimbic system in addiction

    Science.gov (United States)

    van Huijstee, Aile N.; Mansvelder, Huibert D.

    2015-01-01

    Addictive drugs remodel the brain’s reward circuitry, the mesocorticolimbic dopamine (DA) system, by inducing widespread adaptations of glutamatergic synapses. This drug-induced synaptic plasticity is thought to contribute to both the development and the persistence of addiction. This review highlights the synaptic modifications that are induced by in vivo exposure to addictive drugs and describes how these drug-induced synaptic changes may contribute to the different components of addictive behavior, such as compulsive drug use despite negative consequences and relapse. Initially, exposure to an addictive drug induces synaptic changes in the ventral tegmental area (VTA). This drug-induced synaptic potentiation in the VTA subsequently triggers synaptic changes in downstream areas of the mesocorticolimbic system, such as the nucleus accumbens (NAc) and the prefrontal cortex (PFC), with further drug exposure. These glutamatergic synaptic alterations are then thought to mediate many of the behavioral symptoms that characterize addiction. The later stages of glutamatergic synaptic plasticity in the NAc and in particular in the PFC play a role in maintaining addiction and drive relapse to drug-taking induced by drug-associated cues. Remodeling of PFC glutamatergic circuits can persist into adulthood, causing a lasting vulnerability to relapse. We will discuss how these neurobiological changes produced by drugs of abuse may provide novel targets for potential treatment strategies for addiction. PMID:25653591

  19. Modulation of synaptic plasticity by stress hormone associates with plastic alteration of synaptic NMDA receptor in the adult hippocampus.

    Directory of Open Access Journals (Sweden)

    Yiu Chung Tse

    Full Text Available Stress exerts a profound impact on learning and memory, in part, through the actions of adrenal corticosterone (CORT on synaptic plasticity, a cellular model of learning and memory. Increasing findings suggest that CORT exerts its impact on synaptic plasticity by altering the functional properties of glutamate receptors, which include changes in the motility and function of α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid subtype of glutamate receptor (AMPAR that are responsible for the expression of synaptic plasticity. Here we provide evidence that CORT could also regulate synaptic plasticity by modulating the function of synaptic N-methyl-D-aspartate receptors (NMDARs, which mediate the induction of synaptic plasticity. We found that stress level CORT applied to adult rat hippocampal slices potentiated evoked NMDAR-mediated synaptic responses within 30 min. Surprisingly, following this fast-onset change, we observed a slow-onset (>1 hour after termination of CORT exposure increase in synaptic expression of GluN2A-containing NMDARs. To investigate the consequences of the distinct fast- and slow-onset modulation of NMDARs for synaptic plasticity, we examined the formation of long-term potentiation (LTP and long-term depression (LTD within relevant time windows. Paralleling the increased NMDAR function, both LTP and LTD were facilitated during CORT treatment. However, 1-2 hours after CORT treatment when synaptic expression of GluN2A-containing NMDARs is increased, bidirectional plasticity was no longer facilitated. Our findings reveal the remarkable plasticity of NMDARs in the adult hippocampus in response to CORT. CORT-mediated slow-onset increase in GluN2A in hippocampal synapses could be a homeostatic mechanism to normalize synaptic plasticity following fast-onset stress-induced facilitation.

  20. MPTP-meditated hippocampal dopamine deprivation modulates synaptic transmission and activity-dependent synaptic plasticity

    International Nuclear Information System (INIS)

    Zhu Guoqi; Chen Ying; Huang Yuying; Li Qinglin; Behnisch, Thomas

    2011-01-01

    Parkinson's disease (PD)-like symptoms including learning deficits are inducible by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Therefore, it is possible that MPTP may disturb hippocampal memory processing by modulation of dopamine (DA)- and activity-dependent synaptic plasticity. We demonstrate here that intraperitoneal (i.p.) MPTP injection reduces the number of tyrosine hydroxylase (TH)-positive neurons in the substantia nigra (SN) within 7 days. Subsequently, the TH expression level in SN and hippocampus and the amount of DA and its metabolite DOPAC in striatum and hippocampus decrease. DA depletion does not alter basal synaptic transmission and changes pair-pulse facilitation (PPF) of field excitatory postsynaptic potentials (fEPSPs) only at the 30 ms inter-pulse interval. In addition, the induction of long-term potentiation (LTP) is impaired whereas the duration of long-term depression (LTD) becomes prolonged. Since both LTP and LTD depend critically on activation of NMDA and DA receptors, we also tested the effect of DA depletion on NMDA receptor-mediated synaptic transmission. Seven days after MPTP injection, the NMDA receptor-mediated fEPSPs are decreased by about 23%. Blocking the NMDA receptor-mediated fEPSP does not mimic the MPTP-LTP. Only co-application of D1/D5 and NMDA receptor antagonists during tetanization resembled the time course of fEPSP potentiation as observed 7 days after i.p. MPTP injection. Together, our data demonstrate that MPTP-induced degeneration of DA neurons and the subsequent hippocampal DA depletion alter NMDA receptor-mediated synaptic transmission and activity-dependent synaptic plasticity. - Highlights: → I.p. MPTP-injection mediates death of dopaminergic neurons. → I.p. MPTP-injection depletes DA and DOPAC in striatum and hippocampus. → I.p. MPTP-injection does not alter basal synaptic transmission. → Reduction of LTP and enhancement of LTD after i.p. MPTP-injection. → Attenuation of NMDA-receptors mediated

  1. Noise stimulation decreases the concentration of norepinephrine in the rat cochlea.

    Science.gov (United States)

    Vicente-Torres, M A; Gil-Loyzaga, P

    1999-05-14

    The present study was designed to analyze, by using high performance liquid chromatography (HPLC), the effect of acoustic stimulation on the cochlear concentration of norepinephrine (NE). Independently of the rat strain (Long-Evans or Wistar strains), NE concentration decreased about 18% when animals were exposed to white noise (90 dB SPL for 1 h). The same decrease was observed in animals perfused by aortic pathway to remove the blood, indicating that this decrease corresponds exclusively to a neurophysiological process. In fact, these findings could indicate that noise stimulation is involved in the NE release from sympathetic fibers innervating the cochlea. This likely release of NE supports that sympathetic fibers play a functional role in cochleae exposed to noisy situations.

  2. Blood ketone response to norepinephrine-induced free fatty acid in diabetes

    Energy Technology Data Exchange (ETDEWEB)

    Blackard, W G; Omori, Yoshiaki

    1963-04-18

    During 90-minute norepinephrine infusions, blood free fatty acid and ketone responses of Japanese nondiabetic and diabetic subjects were determined. Nonobese diabetic subjects with and without fasting hyperglycemia demonstrated significantly greater blood ketone elevations than nondiabetics. An inverse correlation between obesity and blood ketone response to nonrepinephrine was observed in diabetics. This correlation could not be attributed to varying degrees of fasting hyperglycemia or free fatty acid elevation. Nonobese diabetics with mild fasting hyperglycemia (90 to 150 mg%) exhibited an unexpected greater increase in blood ketones than nonobese diabetics with moderate fasting hyperglycemia (150 to 250 mg%). Differences in free fatty acid elevations were not responsible for this apparent paradox. The magnitude of the hyperketonemic response, though dependent on free fatty elevation, seemed more sensitive to the degree of obesity and the fasting blood glucose level. Fractional ketone body measurements attributed the blood ketone elevations predominantly to ..beta..-hydroxybutyric acid increases. 43 references, 6 figures, 1 table.

  3. Norepinephrine is required to promote wakefulness and for hypocretin-induced arousal in zebrafish.

    Science.gov (United States)

    Singh, Chanpreet; Oikonomou, Grigorios; Prober, David A

    2015-09-16

    Pharmacological studies in mammals suggest that norepinephrine (NE) plays an important role in promoting arousal. However, the role of endogenous NE is unclear, with contradicting reports concerning the sleep phenotypes of mice lacking NE due to mutation of dopamine β-hydroxylase (dbh). To investigate NE function in an alternative vertebrate model, we generated dbh mutant zebrafish. In contrast to mice, these animals exhibit dramatically increased sleep. Surprisingly, despite an increase in sleep, dbh mutant zebrafish have a reduced arousal threshold. These phenotypes are also observed in zebrafish treated with small molecules that inhibit NE signaling, suggesting that they are caused by the lack of NE. Using genetic overexpression of hypocretin (Hcrt) and optogenetic activation of hcrt-expressing neurons, we also find that NE is important for Hcrt-induced arousal. These results establish a role for endogenous NE in promoting arousal and indicate that NE is a critical downstream effector of Hcrt neurons.

  4. Effects of Aroclor 1254 on dopamine and norepinephrine concentrations in pheochromocytoma (PC-12) cells

    International Nuclear Information System (INIS)

    Seegal, R.F.; Brosch, K.; Bush, B.; Ritz, M.; Shain, W.

    1990-01-01

    Pheochromocytoma (PC-12) cells synthesize, store, release and metabolize dopamine (DA) and norepinephrine (NE) in a manner analogous to that observed in the mammalian central nervous system. These cells were used to develop and validate an alternate method to animal testing to assess the effects of a complex environmental mixture of polychlorinated biphenyls (Aroclor 1254) on cellular catecholamine function. Aroclor 1254, at concentrations of 1 to 100 ppm, significantly decreased cellular catecholamine concentrations after 6 hrs. Exposure at 100 ppm for periods of less than an hr increased cellular catecholamine concentrations while longer exposure times (i.e., 1 to 24 hr) decreased cellular catecholamine concentrations. This in vitro depletion of catecholamines is similar to that seen in vivo. Thus, PC-12 cells may be useful for neurochemical evaluation of neurotoxicants with particular reference to effects on catecholaminergic systems

  5. Effect of tyrosine kinase blockade on norepinephrine-induced cytosolic calcium response in rat afferent arterioles

    DEFF Research Database (Denmark)

    Salomonsson, Max; Arendshorst, William J

    2004-01-01

    We used genistein (Gen) and tyrphostin 23 (Tyr-23) to evaluate the importance of tyrosine phosphorylation in norepinephrine (NE)-induced changes in intracellular free calcium concentration ([Ca(2+)](i)) in rat afferent arterioles. [Ca(2+)](i) was measured in microdissected arterioles using...... ratiometric photometry of fura 2 fluorescence. The control [Ca(2+)](i) response to NE (1 microM) consisted of a rapid initial peak followed by a plateau phase sustained above baseline. Pretreatment with the tyrosine kinase inhibitor Tyr-23 (50 microM, 10 min) caused a slow 40% increase in baseline [Ca(2+)](i...... of nifedipine and Tyr-23 were not additive. Nifedipine had no inhibitory effect after Tyr-23 pretreatment, indicating Tyr-23 inhibition of Ca(2+) entry. Another tyrosine kinase inhibitor, Gen (5 and 50 microM), did not affect baseline [Ca(2+)](i). High-dose Gen inhibited the peak and plateau response to NE...

  6. Effects of cadmium on the uptake of dopamine and norepinephrine in rat brain synaptosomes

    International Nuclear Information System (INIS)

    Anon.

    1986-01-01

    Cadmium (Cd) a known environmental contaminant is neurotoxic. Kinetics of cadmium inhibition indicate that the metal may compete with ATP and Na + sites on Na + -K + ATPase in rat brain synaptosomes. Uptake and release processes of catecholamines into the central nervous system are dependent on membrane bound Na + -K + ATPase. It is suggested that the uptake and release processes of dopamine (DA) and norepinephrine (NE) in neurons are energy utilizing and hence are dependent on active ion transport. If the two aforementioned mechanisms are truly interdependent, then any alteration caused by a toxin to either of the above two mechanisms should also cause a parallel change in the other. The purpose of this study was to examine in vitro effects of cadmium chloride on the uptake of DA and NE and the activity of ATPase in the rat brain synaptosome

  7. Lack of effect of norepinephrine on cranial haemodynamics and headache in healthy volunteers

    DEFF Research Database (Denmark)

    Lindholt, M; Petersen, K A; Tvedskov, J F

    2009-01-01

    Stress is a provoking factor for both tension-type headache and migraine attacks. In the present single-blind study, we investigated if stress induced by norepinephrine (NE) could elicit delayed headache in 10 healthy subjects and recorded the cranial arterial responses. NE at a dose of 0...... no changes in these arterial parameters after NE. In both treatment groups three subjects developed delayed headaches. Thus, stress by NE infusion did not result in delayed headache........025 microg kg(-1) min(-1) or placebo was infused for 90 min and the headache was followed for 14 h. Blood flow velocity in the middle cerebral artery (measured with transcranial Doppler) and diameters of the temporal artery and the radial artery (measured with ultrasound) were followed for 2 h. There were...

  8. The role of dopamine and norepinephrine in depression and antidepressant treatment.

    Science.gov (United States)

    Nutt, David J

    2006-01-01

    Most antidepressants in use today are descendants of the monoamine oxidase inhibitor iproniazid and the tricyclic agent imipramine. These agents were both originally developed for other indications but then were serendipitously determined to have antidepressant effects. Elucidation of the mechanisms of action of these first antidepressants, along with those of reserpine and amphetamine, led to the monoamine theories of depression. Through the past several decades, approaches undertaken to clarify the roles of the neurotransmitters norepinephrine, dopamine, and serotonin in depression have included animal studies, human biological and postmortem studies, inferences drawn from antidepressant drug actions, and challenge or depletion studies; most recently, brain imaging studies have proved to be especially informative. This research has identified novel potential targets, with the goal of developing new antidepressant drugs with better efficacy and faster onset of action than current "gold-standard" treatments.

  9. Spike timing analysis in neural networks with unsupervised synaptic plasticity

    Science.gov (United States)

    Mizusaki, B. E. P.; Agnes, E. J.; Brunnet, L. G.; Erichsen, R., Jr.

    2013-01-01

    The synaptic plasticity rules that sculpt a neural network architecture are key elements to understand cortical processing, as they may explain the emergence of stable, functional activity, while avoiding runaway excitation. For an associative memory framework, they should be built in a way as to enable the network to reproduce a robust spatio-temporal trajectory in response to an external stimulus. Still, how these rules may be implemented in recurrent networks and the way they relate to their capacity of pattern recognition remains unclear. We studied the effects of three phenomenological unsupervised rules in sparsely connected recurrent networks for associative memory: spike-timing-dependent-plasticity, short-term-plasticity and an homeostatic scaling. The system stability is monitored during the learning process of the network, as the mean firing rate converges to a value determined by the homeostatic scaling. Afterwards, it is possible to measure the recovery efficiency of the activity following each initial stimulus. This is evaluated by a measure of the correlation between spike fire timings, and we analysed the full memory separation capacity and limitations of this system.

  10. Mood is indirectly related to serotonin, norepinephrine and dopamine levels in humans: a meta-analysis of monoamine depletion studies

    NARCIS (Netherlands)

    Ruhe, H. G.; Mason, N. S.; Schene, A. H.

    2007-01-01

    Dysfunction in the monoamine systems of serotonin (5-HT), norepinephrine (NE) and dopamine (DA) may causally be related to major depressive disorder (MDD). Monoamine depletion studies investigate the direct effects of monoamines on mood. Acute tryptophan depletion (ATD) or para-chlorophenylalanine

  11. Poincaré plot width, morning urine norepinephrine levels, and autonomic imbalance in children with obstructive sleep apnea.

    Science.gov (United States)

    Chaidas, Konstantinos; Tsaoussoglou, Marina; Theodorou, Emmanouel; Lianou, Loukia; Chrousos, George; Kaditis, Athanasios G

    2014-08-01

    Obstructive sleep apnea (OSA) in childhood is accompanied by sympathetic overflow unopposed by the parasympathetic tone. Complex methods like power spectral analysis of heart rate variability have been applied to study this imbalance. In this report, width of Poincaré scattergram of the R-R interval (parasympathetic tone) and morning urine norepinephrine concentration (sympathetic activity) were used to assess autonomic imbalance. Poincaré plot was obtained from the electrocardiographic channel of nocturnal polysomnography and its width was measured, and norepinephrine-to-creatinine concentration ratio was calculated in morning urine specimen. Twenty children with obstructive sleep apnea and moderate-to-severe nocturnal hypoxemia (oxygen saturation of hemoglobin [SpO(2)] nadir plot width (318.7 ± 139.3 ms) and higher ln-transformed urine norepinephrine-to-creatinine ratio (4.5 ± 0.6) than control subjects (484.2 ± 104.4 ms and 3.8 ± 0.4, respectively; P plot width (P = 0.02). Subjects with obstructive sleep apnea and moderate-to-severe nocturnal hypoxemia have enhanced sympathetic activity and reduced parasympathetic drive. Poincaré plot width and urine norepinephrine levels are simple measures of autonomic imbalance in pediatric obstructive sleep apnea. Copyright © 2014 Elsevier Inc. All rights reserved.

  12. Nicotinic mechanisms influencing synaptic plasticity in the hippocampus

    Institute of Scientific and Technical Information of China (English)

    Andon Nicholas PLACZEK; Tao A ZHANG; John Anthony DANI

    2009-01-01

    Nicotinic acetylcholine receptors (nAChRs) are expressed throughout the hippocampus, and nicotinic signaling plays an important role in neuronal function. In the context of learning and memory related behaviors associated with hippocampal function, a potentially significant feature of nAChR activity is the impact it has on synaptic plasticity. Synaptic plasticity in hippocampal neurons has long been considered a contributing cellular mechanism of learning and memory. These same kinds of cellular mechanisms are a factor in the development of nicotine addiction. Nicotinic signaling has been demonstrated by in vitro studies to affect synaptic plasticity in hippocampal neurons via multiple steps, and the signaling has also been shown to evoke synaptic plasticity in vivo. This review focuses on the nAChRs subtypes that contribute to hippocampal synaptic plasticity at the cellular and circuit level. It also considers nicotinic influences over long-term changes in the hippocampus that may contribute to addiction.

  13. Synaptic transmission block by presynaptic injection of oligomeric amyloid beta

    Science.gov (United States)

    Moreno, Herman; Yu, Eunah; Pigino, Gustavo; Hernandez, Alejandro I.; Kim, Natalia; Moreira, Jorge E.; Sugimori, Mutsuyuki; Llinás, Rodolfo R.

    2009-01-01

    Early Alzheimer's disease (AD) pathophysiology is characterized by synaptic changes induced by degradation products of amyloid precursor protein (APP). The exact mechanisms of such modulation are unknown. Here, we report that nanomolar concentrations of intraaxonal oligomeric (o)Aβ42, but not oAβ40 or extracellular oAβ42, acutely inhibited synaptic transmission at the squid giant synapse. Further characterization of this phenotype demonstrated that presynaptic calcium currents were unaffected. However, electron microscopy experiments revealed diminished docked synaptic vesicles in oAβ42-microinjected terminals, without affecting clathrin-coated vesicles. The molecular events of this modulation involved casein kinase 2 and the synaptic vesicle rapid endocytosis pathway. These findings open the possibility of a new therapeutic target aimed at ameliorating synaptic dysfunction in AD. PMID:19304802

  14. [Involvement of aquaporin-4 in synaptic plasticity, learning and memory].

    Science.gov (United States)

    Wu, Xin; Gao, Jian-Feng

    2017-06-25

    Aquaporin-4 (AQP-4) is the predominant water channel in the central nervous system (CNS) and primarily expressed in astrocytes. Astrocytes have been generally believed to play important roles in regulating synaptic plasticity and information processing. However, the role of AQP-4 in regulating synaptic plasticity, learning and memory, cognitive function is only beginning to be investigated. It is well known that synaptic plasticity is the prime candidate for mediating of learning and memory. Long term potentiation (LTP) and long term depression (LTD) are two forms of synaptic plasticity, and they share some but not all the properties and mechanisms. Hippocampus is a part of limbic system that is particularly important in regulation of learning and memory. This article is to review some research progresses of the function of AQP-4 in synaptic plasticity, learning and memory, and propose the possible role of AQP-4 as a new target in the treatment of cognitive dysfunction.

  15. The role of serotonin and norepinephrine in sleep-waking activity.

    Science.gov (United States)

    Morgane, P J; Stern, W C

    1975-11-01

    A critical review of the evidences relating the biogenic amines serotonin and norepinephrine to the states of slow-wave and rapid eye movement (REM) sleep is presented. Various alternative explanations for specific chemical regulation of the individual sleep states, including the phasic events of REM sleep, are evaluated within the overall framework of the monoamine theory of sleep. Several critical neuropsychopharmacological studies relating to metabolsim of the amines in relation to sleep-waking behavior are presented. Models of the chemical neuronal circuitry involved in sleep-waking activity are derived and interactions between several brainstem nuclei, particularly the raphé complex and locus coeruleus, are discussed. Activity in these aminergic systems in relation to oscillations in the sleep-waking cycles is evaluated. In particular, the assessment of single cell activity in specific chemical systems in relations to chemical models of sleep is reviewed. Overall, it appears that the biogenic amines, especially serotonin and norepinephrine, play key roles in the generation and maintenance of the sleep states. These neurotransmitters participate in some manner in the "triggering" processes necessary for actuating each sleep phase and in regulating the transitions from sleep to waking activity. The biogenic amines are, however, probably not "sleep factors" or direct inducers of the sleep states. Rather, they appear to be components of a multiplicity of interacting chemical circuitry in the brain whose activity maintains various chemical balances in different brain regions. Shifts in these balances appear to be involved in the triggering and maintenance of the various states comprising the vigilance continuum.

  16. Stress-related hormone norepinephrine induces interleukin-6 expression in GES-1 cells

    International Nuclear Information System (INIS)

    Yang, R.; Lin, Q.; Gao, H.B.; Zhang, P.

    2014-01-01

    In the current literature, there is evidence that psychological factors can affect the incidence and progression of some cancers. Interleukin 6 (IL-6) is known to be elevated in individuals experiencing chronic stress and is also involved in oncogenesis and cancer progression. However, the precise mechanism of IL-6 induction by the stress-related hormone norepinephrine (NE) is not clear, and, furthermore, there are no reports about the effect of NE on IL-6 expression in gastric epithelial cells. In this study, we examined the effect of NE on IL-6 expression in immortalized human gastric epithelial cells (GES-1 cells). Using real-time PCR and enzyme-linked immunoassay, we demonstrated that NE can induce IL-6 mRNA and protein expression in GES-1 cells. The induction is through the β-adrenergic receptor-cAMP-protein kinase A pathway and mainly at the transcriptional level. Progressive 5′-deletions and site-directed mutagenesis of the parental construct show that, although activating-protein-1 (AP-1), cAMP-responsive element binding protein (CREB), CCAAT-enhancer binding protein-β (C/EBP-β), and nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) binding sites are all required in the basal transcription of IL-6, only AP-1 and CREB binding sites in the IL-6 promoter are required in NE-induced IL-6 expression. The results suggest that chronic stress may increase IL-6 secretion of human gastric epithelial cells, at least in part, by the stress-associated hormone norepinephrine, and provides basic data on stress and gastric cancer progression

  17. Stress-related hormone norepinephrine induces interleukin-6 expression in GES-1 cells

    Energy Technology Data Exchange (ETDEWEB)

    Yang, R.; Lin, Q.; Gao, H.B.; Zhang, P. [Department of Biochemistry and Molecular Cell Biology, School of Medicine, Shanghai Jiao Tong University, Shanghai, China, Department of Biochemistry and Molecular Cell Biology, School of Medicine, Shanghai Jiao Tong University, Shanghai (China)

    2014-02-17

    In the current literature, there is evidence that psychological factors can affect the incidence and progression of some cancers. Interleukin 6 (IL-6) is known to be elevated in individuals experiencing chronic stress and is also involved in oncogenesis and cancer progression. However, the precise mechanism of IL-6 induction by the stress-related hormone norepinephrine (NE) is not clear, and, furthermore, there are no reports about the effect of NE on IL-6 expression in gastric epithelial cells. In this study, we examined the effect of NE on IL-6 expression in immortalized human gastric epithelial cells (GES-1 cells). Using real-time PCR and enzyme-linked immunoassay, we demonstrated that NE can induce IL-6 mRNA and protein expression in GES-1 cells. The induction is through the β-adrenergic receptor-cAMP-protein kinase A pathway and mainly at the transcriptional level. Progressive 5′-deletions and site-directed mutagenesis of the parental construct show that, although activating-protein-1 (AP-1), cAMP-responsive element binding protein (CREB), CCAAT-enhancer binding protein-β (C/EBP-β), and nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) binding sites are all required in the basal transcription of IL-6, only AP-1 and CREB binding sites in the IL-6 promoter are required in NE-induced IL-6 expression. The results suggest that chronic stress may increase IL-6 secretion of human gastric epithelial cells, at least in part, by the stress-associated hormone norepinephrine, and provides basic data on stress and gastric cancer progression.

  18. Benzodiazepines: rat pinealocyte binding sites and augmentation of norepinephrine-stimulated N-acetyltransferase activity

    Energy Technology Data Exchange (ETDEWEB)

    Matthew, E.; Parfitt, A.G.; Sugden, D.; Engelhardt, D.L.; Zimmerman, E.A.; Klein, D.C.

    1984-02-01

    Studies of (/sup 3/H)diazepam binding to intact rat pineal cells were carried out in tissue culture preparations. The binding was saturable, reversible and proportional to the number of cells used. Scatchard analysis resulted in a linear plot (Kd . 23 nM, maximum binding sites (Bmax) . 1.56 pmol/mg of protein for cells in monolayer culture; Kd . 7 nM, Bmax . 1.3 pmol/mg of protein for cells in suspension culture). Inhibition constants (Ki) for clonazepam (500 nM), flunitrazepam (38 nM) and Ro-5-4864 (5 nM) indicated that the binding sites were probably of the ''peripheral'' type. In addition, the effects of diazepam on norepinephrine-stimulated N-acetyltransferase (NAT) activity were studied in organ culture and dissociated cell culture. Diazepam (10-50 microM) both prolonged and increased the magnitude of the norepinephrine-induced increase in NAT activity but did not affect the initial rate of rise of enzyme activity. The effect was dose-dependent and was also seen with clonazepam, flunitrazepam and Ro-5-4864, but not with Ro-15-1788. Diazepam, by itself, at these concentrations, had no effect on NAT, but enzyme activity was increased by higher concentrations (0.1-1 mM). Although a relationship between the (/sup 3/H)diazepam binding sites described here and the effect of benzodiazepines on NAT cannot be established from these studies, the data suggest that the benzodiazepines may alter melatonin levels through their action on NAT.

  19. Improved preclinical cardiovascular therapeutic indices with long-term inhibition of norepinephrine reuptake using reboxetine

    International Nuclear Information System (INIS)

    Fossa, Anthony A.; Wisialowski, Todd A.; Cremers, Thomas; Hart, Marieke van der; Tseng, Elaine; Deng, Shibing; Rollema, Hans; Wang, Ellen Q.

    2012-01-01

    Norepinephrine reuptake inhibitors (NRIs) acutely increase norepinephrine (NE) levels, but therapeutic antidepressant activity is only observed after weeks of treatment because central NE levels progressively increase during continued drug exposure. Similarly, while NRIs acutely increase blood pressure (BP) and heart rate (HR) due to enhanced sympathetic neurotransmission, chronic treatment changes the responsiveness of the central noradrenergic system and suppresses these effects via autonomic regulation. To better understand the relationship between NE increases and cardiovascular safety, we investigated acute and chronic effects of the NRI reboxetine on central NE release and on BP and HR and electrical alternans, a measure of arrhythmia liability, in guinea pigs. NE release was assessed by microdialysis in medial prefrontal cortex (mPFC) and hypothalamic paraventricular nucleus (PVN); BP and HR were measured by telemetry. Animals were treated for 28 days with 15 mg/kg/day of reboxetine or vehicle via an osmotic minipump and then challenged with acute intravenous doses of reboxetine. Animals chronically treated with reboxetine had 2-fold higher extracellular basal NE levels in mPFC and PVN compared to basal levels after chronic vehicle treatment. BP was significantly increased after the first day of treatment, and gradually returned to vehicle levels by day 21. These data indicate that chronic NRI treatment may lead to an increase in central NE levels and a concomitant reduction in BP based on exposure–response curves compared to vehicle treatment, suggesting a larger separation between preclinical estimates of efficacy vs. safety compared to acute NRI treatment. -- Highlights: ► Acute RBX produces blood pressure increases acutely that decrease with chronic RBX ► Chronic RBX increases brain NE levels, a preclinical surrogate of improved efficacy ► Short-term screening of NRI often underestimates the chronic therapeutic index ► Chronic cardiovascular

  20. Norepinephrine and dopamine increase motility, biofilm formation and virulence of Vibrio harveyi

    Directory of Open Access Journals (Sweden)

    Qian eYang

    2014-11-01

    Full Text Available Vibrio harveyi is one of the major pathogens of aquatic organisms, affecting both vertebrates and invertebrates, and causes important losses in the aquaculture industry. In order to develop novel methods to control disease caused by this pathogen, we need to obtain a better understanding of pathogenicity mechanisms. Sensing of catecholamines increases both growth and production of virulence-related factors in pathogens of terrestrial animals and humans. However, at this moment, knowledge on the impact of catecholamines on the virulence of pathogens of aquatic organisms is lacking. In the present study, we report that in V. harveyi, norepinephrine and dopamine increased growth in serum-supplemented medium, siderophore production, swimming motility and expression of genes involved in flagellar motility, biofilm formation, and exopolysaccharide production. Consistent with this, pretreatment of V. harveyi with catecholamines prior to inoculation into the rearing water resulted in significantly decreased survival of gnotobiotic brine shrimp larvae, when compared to larvae challenged with untreated V. harveyi. Further, norepinephrine-induced effects could be neutralized by α-adrenergic antagonists or by the bacterial catecholamine receptor antagonist LED209, but not by β-adrenergic or dopaminergic antagonists. Dopamine-induced effects could be neutralized by dopaminergic antagonists or LED209, but not by adrenergic antagonists. Together, our results indicate that catecholamine sensing increases the success of transmission of V. harveyi and that interfering with catecholamine sensing might be an interesting strategy to control vibriosis in aquaculture. We hypothesise that upon tissue and/or hemocyte damage during infection, pathogens come into contact with elevated catecholamine levels, and that this stimulates the expression of virulence factors that are required to colonize a new host.

  1. Isolating the Norepinephrine Pathway Comparing Lithium in Bipolar Patients to SSRIs in Depressive Patients

    Directory of Open Access Journals (Sweden)

    Andy R. Eugene

    2015-07-01

    Full Text Available Introduction: The purpose of this investigatory neuroimaging analysis was done to better understand the pharmacodynamics of Lithium by isolating the norepinephrine pathway in the brain. To accomplish this, we compared patients with Bipolar Disorder treated with Lithium to patients diagnosed with Major Depression or Depressive Disorder who are treated with Selective Serotonin Reuptake Inhibitors (SSRIs.Methodology: We used Standardized Low Resolution Brain Electrotomography to calculate the whole brain, voxel-by-voxel, unpaired t-tests Statistical non-Parametric Maps. For our first electrophysiological neuroimaging investigation, we compared 46 patients (average age = 34 ± 16.5 diagnosed with Bipolar Affective Disorder to three patient groups all diagnosed with Major Depression or Depressive Episode. The first is with 48 patients diagnosed with Major Depression or Depressive Episode (average age = 49 ± 12.9, the second to 16 male depressive patients (average age = 45 ± 15.1, and the final comparison to 32 depressive females (average age = 50 ± 11.7.Results: The results of sLORETA three-dimensional statistical non-parametric maps illustrated that Lithium influenced an increase in neurotransmission in the right Superior TemporalGyrus (t=1.403, p=0.00780, Fusiform Gyrus (t=1.26, and Parahippocampal Gyrus (t=1.29.Moreover, an increased in neuronal function was found was also identified at the Cingulate Gyrus(t=1.06, p=0.01200.Conclusion: We are proposing a translational clinical biological marker for patients diagnosed with Bipolar Disorder to guide physicians during the course of Lithium therapy and have identified neuroanatomical structures influenced by norepinephrine.

  2. Improved preclinical cardiovascular therapeutic indices with long-term inhibition of norepinephrine reuptake using reboxetine

    Energy Technology Data Exchange (ETDEWEB)

    Fossa, Anthony A., E-mail: anthony.fossa@icardiac.com [Department of Global Safety Pharmacology, Department of Pharmacokinetics, Dynamics and Metabolism, and Neuroscience, Pfizer Global Research and Development Eastern Point Road, Groton, CT 06340 (United States); Wisialowski, Todd A. [Department of Global Safety Pharmacology, Department of Pharmacokinetics, Dynamics and Metabolism, and Neuroscience, Pfizer Global Research and Development Eastern Point Road, Groton, CT 06340 (United States); Cremers, Thomas; Hart, Marieke van der [Brains On-Line B.V., University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen (Netherlands); Tseng, Elaine; Deng, Shibing; Rollema, Hans; Wang, Ellen Q. [Department of Global Safety Pharmacology, Department of Pharmacokinetics, Dynamics and Metabolism, and Neuroscience, Pfizer Global Research and Development Eastern Point Road, Groton, CT 06340 (United States)

    2012-11-01

    Norepinephrine reuptake inhibitors (NRIs) acutely increase norepinephrine (NE) levels, but therapeutic antidepressant activity is only observed after weeks of treatment because central NE levels progressively increase during continued drug exposure. Similarly, while NRIs acutely increase blood pressure (BP) and heart rate (HR) due to enhanced sympathetic neurotransmission, chronic treatment changes the responsiveness of the central noradrenergic system and suppresses these effects via autonomic regulation. To better understand the relationship between NE increases and cardiovascular safety, we investigated acute and chronic effects of the NRI reboxetine on central NE release and on BP and HR and electrical alternans, a measure of arrhythmia liability, in guinea pigs. NE release was assessed by microdialysis in medial prefrontal cortex (mPFC) and hypothalamic paraventricular nucleus (PVN); BP and HR were measured by telemetry. Animals were treated for 28 days with 15 mg/kg/day of reboxetine or vehicle via an osmotic minipump and then challenged with acute intravenous doses of reboxetine. Animals chronically treated with reboxetine had 2-fold higher extracellular basal NE levels in mPFC and PVN compared to basal levels after chronic vehicle treatment. BP was significantly increased after the first day of treatment, and gradually returned to vehicle levels by day 21. These data indicate that chronic NRI treatment may lead to an increase in central NE levels and a concomitant reduction in BP based on exposure–response curves compared to vehicle treatment, suggesting a larger separation between preclinical estimates of efficacy vs. safety compared to acute NRI treatment. -- Highlights: ► Acute RBX produces blood pressure increases acutely that decrease with chronic RBX ► Chronic RBX increases brain NE levels, a preclinical surrogate of improved efficacy ► Short-term screening of NRI often underestimates the chronic therapeutic index ► Chronic cardiovascular

  3. All-optical functional synaptic connectivity mapping in acute brain slices using the calcium integrator CaMPARI.

    Science.gov (United States)

    Zolnik, Timothy A; Sha, Fern; Johenning, Friedrich W; Schreiter, Eric R; Looger, Loren L; Larkum, Matthew E; Sachdev, Robert N S

    2017-03-01

    The genetically encoded fluorescent calcium integrator calcium-modulated photoactivatable ratiobetric integrator (CaMPARI) reports calcium influx induced by synaptic and neural activity. Its fluorescence is converted from green to red in the presence of violet light and calcium. The rate of conversion - the sensitivity to activity - is tunable and depends on the intensity of violet light. Synaptic activity and action potentials can independently initiate significant CaMPARI conversion. The level of conversion by subthreshold synaptic inputs is correlated to the strength of input, enabling optical readout of relative synaptic strength. When combined with optogenetic activation of defined presynaptic neurons, CaMPARI provides an all-optical method to map synaptic connectivity. The calcium-modulated photoactivatable ratiometric integrator (CaMPARI) is a genetically encoded calcium integrator that facilitates the study of neural circuits by permanently marking cells active during user-specified temporal windows. Permanent marking enables measurement of signals from large swathes of tissue and easy correlation of activity with other structural or functional labels. One potential application of CaMPARI is labelling neurons postsynaptic to specific populations targeted for optogenetic stimulation, giving rise to all-optical functional connectivity mapping. Here, we characterized the response of CaMPARI to several common types of neuronal calcium signals in mouse acute cortical brain slices. Our experiments show that CaMPARI is effectively converted by both action potentials and subthreshold synaptic inputs, and that conversion level is correlated to synaptic strength. Importantly, we found that conversion rate can be tuned: it is linearly related to light intensity. At low photoconversion light levels CaMPARI offers a wide dynamic range due to slower conversion rate; at high light levels conversion is more rapid and more sensitive to activity. Finally, we employed Ca

  4. Circadian clocks, rhythmic synaptic plasticity and the sleep-wake cycle in zebrafish.

    Science.gov (United States)

    Elbaz, Idan; Foulkes, Nicholas S; Gothilf, Yoav; Appelbaum, Lior

    2013-01-01

    The circadian clock and homeostatic processes are fundamental mechanisms that regulate sleep. Surprisingly, despite decades of research, we still do not know why we sleep. Intriguing hypotheses suggest that sleep regulates synaptic plasticity and consequently has a beneficial role in learning and memory. However, direct evidence is still limited and the molecular regulatory mechanisms remain unclear. The zebrafish provides a powerful vertebrate model system that enables simple genetic manipulation, imaging of neuronal circuits and synapses in living animals, and the monitoring of behavioral performance during day and night. Thus, the zebrafish has become an attractive model to study circadian and homeostatic processes that regulate sleep. Zebrafish clock- and sleep-related genes have been cloned, neuronal circuits that exhibit circadian rhythms of activity and synaptic plasticity have been studied, and rhythmic behavioral outputs have been characterized. Integration of this data could lead to a better understanding of sleep regulation. Here, we review the progress of circadian clock and sleep studies in zebrafish with special emphasis on the genetic and neuroendocrine mechanisms that regulate rhythms of melatonin secretion, structural synaptic plasticity, locomotor activity and sleep.

  5. Circadian clocks, rhythmic synaptic plasticity and the sleep-wake cycle in zebrafish

    Directory of Open Access Journals (Sweden)

    Idan eElbaz

    2013-02-01

    Full Text Available The circadian clock and homeostatic processes are fundamental mechanisms that regulate sleep. Surprisingly, despite decades of research, we still do not know why we sleep. Intriguing hypotheses suggest that sleep regulates synaptic plasticity and consequently has a beneficial role in learning and memory. However, direct evidence is still limited and the molecular regulatory mechanisms remain unclear. The zebrafish provides a powerful vertebrate model system that enables simple genetic manipulation, imaging of neuronal circuits and synapses in living animals, and the monitoring of behavioral performance during day and night. Thus, the zebrafish has become an attractive model to study circadian and homeostatic processes that regulate sleep. Zebrafish clock- and sleep-related genes have been cloned, neuronal circuits that exhibit circadian rhythms of activity and synaptic plasticity have been studied, and rhythmic behavioral outputs have been characterized. Integration of this data could lead to a better understanding of sleep regulation. Here, we review the progress of circadian clock and sleep studies in zebrafish with special emphasis on the genetic and neuroendocrine mechanisms that regulate rhythms of melatonin secretion, structural synaptic plasticity, locomotor activity and sleep.

  6. Organising to Enable Innovation

    DEFF Research Database (Denmark)

    Brink, Tove

    2016-01-01

    The purpose of this conceptual paper is to reveal how organising can enable innovation across organisational layers and organisational units. This approach calls for a cross-disciplinary literature review. The aim is to provide an integrated understanding of innovation in an organisational approach....... The findings reveal a continous organising process between individual/ team creativity and organisational structures/control to enable innovation at firm level. Organising provides a dynamic approach and contains the integrated reconstruction of creativity, structures and boundaries for enhanced balance...... of explorative and exploitative learning in uncertain environments. Shedding light on the cross-disciplinary theories to organise innovation provides a contribution at the firm level to enable innovation....

  7. Unsupervised discrimination of patterns in spiking neural networks with excitatory and inhibitory synaptic plasticity.

    Science.gov (United States)

    Srinivasa, Narayan; Cho, Youngkwan

    2014-01-01

    A spiking neural network model is described for learning to discriminate among spatial patterns in an unsupervised manner. The network anatomy consists of source neurons that are activated by external inputs, a reservoir that resembles a generic cortical layer with an excitatory-inhibitory (EI) network and a sink layer of neurons for readout. Synaptic plasticity in the form of STDP is imposed on all the excitatory and inhibitory synapses at all times. While long-term excitatory STDP enables sparse and efficient learning of the salient features in inputs, inhibitory STDP enables this learning to be stable by establishing a balance between excitatory and inhibitory currents at each neuron in the network. The synaptic weights between source and reservoir neurons form a basis set for the input patterns. The neural trajectories generated in the reservoir due to input stimulation and lateral connections between reservoir neurons can be readout by the sink layer neurons. This activity is used for adaptation of synapses between reservoir and sink layer neurons. A new measure called the discriminability index (DI) is introduced to compute if the network can discriminate between old patterns already presented in an initial training session. The DI is also used to compute if the network adapts to new patterns without losing its ability to discriminate among old patterns. The final outcome is that the network is able to correctly discriminate between all patterns-both old and new. This result holds as long as inhibitory synapses employ STDP to continuously enable current balance in the network. The results suggest a possible direction for future investigation into how spiking neural networks could address the stability-plasticity question despite having continuous synaptic plasticity.

  8. Stochastic lattice model of synaptic membrane protein domains.

    Science.gov (United States)

    Li, Yiwei; Kahraman, Osman; Haselwandter, Christoph A

    2017-05-01

    Neurotransmitter receptor molecules, concentrated in synaptic membrane domains along with scaffolds and other kinds of proteins, are crucial for signal transmission across chemical synapses. In common with other membrane protein domains, synaptic domains are characterized by low protein copy numbers and protein crowding, with rapid stochastic turnover of individual molecules. We study here in detail a stochastic lattice model of the receptor-scaffold reaction-diffusion dynamics at synaptic domains that was found previously to capture, at the mean-field level, the self-assembly, stability, and characteristic size of synaptic domains observed in experiments. We show that our stochastic lattice model yields quantitative agreement with mean-field models of nonlinear diffusion in crowded membranes. Through a combination of analytic and numerical solutions of the master equation governing the reaction dynamics at synaptic domains, together with kinetic Monte Carlo simulations, we find substantial discrepancies between mean-field and stochastic models for the reaction dynamics at synaptic domains. Based on the reaction and diffusion properties of synaptic receptors and scaffolds suggested by previous experiments and mean-field calculations, we show that the stochastic reaction-diffusion dynamics of synaptic receptors and scaffolds provide a simple physical mechanism for collective fluctuations in synaptic domains, the molecular turnover observed at synaptic domains, key features of the observed single-molecule trajectories, and spatial heterogeneity in the effective rates at which receptors and scaffolds are recycled at the cell membrane. Our work sheds light on the physical mechanisms and principles linking the collective properties of membrane protein domains to the stochastic dynamics that rule their molecular components.

  9. Alteration of synaptic connectivity of oligodendrocyte precursor cells following demyelination

    Science.gov (United States)

    Sahel, Aurélia; Ortiz, Fernando C.; Kerninon, Christophe; Maldonado, Paloma P.; Angulo, María Cecilia; Nait-Oumesmar, Brahim

    2015-01-01

    Oligodendrocyte precursor cells (OPCs) are a major source of remyelinating oligodendrocytes in demyelinating diseases such as Multiple Sclerosis (MS). While OPCs are innervated by unmyelinated axons in the normal brain, the fate of such synaptic contacts after demyelination is still unclear. By combining electrophysiology and immunostainings in different transgenic mice expressing fluorescent reporters, we studied the synaptic innervation of OPCs in the model of lysolecithin (LPC)-induced demyelination of corpus callosum. Synaptic innervation of reactivated OPCs in the lesion was revealed by the presence of AMPA receptor-mediated synaptic currents, VGluT1+ axon-OPC contacts in 3D confocal reconstructions and synaptic junctions observed by electron microscopy. Moreover, 3D confocal reconstructions of VGluT1 and NG2 immunolabeling showed the existence of glutamatergic axon-OPC contacts in post-mortem MS lesions. Interestingly, patch-clamp recordings in LPC-induced lesions demonstrated a drastic decrease in spontaneous synaptic activity of OPCs early after demyelination that was not caused by an impaired conduction of compound action potentials. A reduction in synaptic connectivity was confirmed by the lack of VGluT1+ axon-OPC contacts in virtually all rapidly proliferating OPCs stained with EdU (50-ethynyl-20-deoxyuridine). At the end of the massive proliferation phase in lesions, the proportion of innervated OPCs rapidly recovers, although the frequency of spontaneous synaptic currents did not reach control levels. In conclusion, our results demonstrate that newly-generated OPCs do not receive synaptic inputs during their active proliferation after demyelination, but gain synapses during the remyelination process. Hence, glutamatergic synaptic inputs may contribute to inhibit OPC proliferation and might have a physiopathological relevance in demyelinating disorders. PMID:25852473

  10. Leucine-rich repeat-containing synaptic adhesion molecules as organizers of synaptic specificity and diversity.

    Science.gov (United States)

    Schroeder, Anna; de Wit, Joris

    2018-04-09

    The brain harbors billions of neurons that form distinct neural circuits with exquisite specificity. Specific patterns of connectivity between distinct neuronal cell types permit the transfer and computation of information. The molecular correlates that give rise to synaptic specificity are incompletely understood. Recent studies indicate that cell-surface molecules are important determinants of cell type identity and suggest that these are essential players in the specification of synaptic connectivity. Leucine-rich repeat (LRR)-containing adhesion molecules in particular have emerged as key organizers of excitatory and inhibitory synapses. Here, we discuss emerging evidence that LRR proteins regulate the assembly of specific connectivity patterns across neural circuits, and contribute to the diverse structural and functional properties of synapses, two key features that are critical for the proper formation and function of neural circuits.

  11. Ankyrins: Roles in synaptic biology and pathology.

    Science.gov (United States)

    Smith, Katharine R; Penzes, Peter

    2018-05-03

    Ankyrins are broadly expressed adaptors that organize diverse membrane proteins into specialized domains and link them to the sub-membranous cytoskeleton. In neurons, ankyrins are known to have essential roles in organizing the axon initial segment and nodes of Ranvier. However, recent studies have revealed novel functions for ankyrins at synapses, where they organize and stabilize neurotransmitter receptors, modulate dendritic spine morphology and control adhesion to the presynaptic site. Ankyrin genes have also been highly associated with a range of neurodevelopmental and psychiatric diseases, including bipolar disorder, schizophrenia and autism, which all demonstrate overlap in their genetics, mechanisms and phenotypes. This review discusses the novel synaptic functions of ankyrin proteins in neurons, and places these exciting findings in the context of ANK genes as key neuropsychiatric disorder risk-factors. Copyright © 2018 Elsevier Inc. All rights reserved.

  12. Alzheimer's disease: synaptic dysfunction and Abeta

    LENUS (Irish Health Repository)

    Shankar, Ganesh M

    2009-11-23

    Abstract Synapse loss is an early and invariant feature of Alzheimer\\'s disease (AD) and there is a strong correlation between the extent of synapse loss and the severity of dementia. Accordingly, it has been proposed that synapse loss underlies the memory impairment evident in the early phase of AD and that since plasticity is important for neuronal viability, persistent disruption of plasticity may account for the frank cell loss typical of later phases of the disease. Extensive multi-disciplinary research has implicated the amyloid β-protein (Aβ) in the aetiology of AD and here we review the evidence that non-fibrillar soluble forms of Aβ are mediators of synaptic compromise. We also discuss the possible mechanisms of Aβ synaptotoxicity and potential targets for therapeutic intervention.

  13. Divergent effects of norepinephrine, dopamine and substance P on the activation, differentiation and effector functions of human cytotoxic T lymphocytes

    Directory of Open Access Journals (Sweden)

    Niggemann Bernd

    2009-12-01

    Full Text Available Abstract Background Neurotransmitters are important regulators of the immune system, with very distinct and varying effects on different leukocyte subsets. So far little is known about the impact of signals mediated by neurotransmitters on the function of CD8+ T lymphocytes. Therefore, we investigated the influence of norepinephrine, dopamine and substance P on the key tasks of CD8+ T lymphocytes: activation, migration, extravasation and cytotoxicity. Results The activation of naïve CD8+ T lymphocytes by CD3/CD28 cross-linking was inhibited by norepinephrine and dopamine, which was caused by a downregulation of interleukin (IL-2 expression via Erk1/2 and NF-κB inhibition. Furthermore, all of the investigated neurotransmitters increased the spontaneous migratory activity of naïve CD8+ T lymphocytes with dopamine being the strongest inducer. In contrast, activated CD8+ T lymphocytes showed a reduced migratory activity in the presence of norepinephrine and substance P. With regard to extravasation we found norepinephrine to induce adhesion of activated CD8+ T cells: norepinephrine increased the interleukin-8 release from endothelium, which in turn had effect on the activated CXCR1+ CD8+ T cells. At last, release of cytotoxic granules from activated cells in response to CD3 cross-linking was not influenced by any of the investigated neurotransmitters, as we have analyzed by measuring the β-hexosamidase release. Conclusion Neurotransmitters are specific modulators of CD8+ T lymphocytes not by inducing any new functions, but by fine-tuning their key tasks. The effect can be either stimulatory or suppressive depending on the activation status of the cells.

  14. Shank synaptic scaffold proteins: keys to understanding the pathogenesis of autism and other synaptic disorders.

    Science.gov (United States)

    Sala, Carlo; Vicidomini, Cinzia; Bigi, Ilaria; Mossa, Adele; Verpelli, Chiara

    2015-12-01

    Shank/ProSAP proteins are essential to synaptic formation, development, and function. Mutations in the family of SHANK genes are strongly associated with autism spectrum disorders (ASD) and other neurodevelopmental and neuropsychiatric disorders, such as intellectual disability (ID), and schizophrenia. Thus, the term 'Shankopathies' identifies a number of neuronal diseases caused by alteration of Shank protein expression leading to abnormal synaptic development. With this review we want to summarize the major genetic, molecular, behavior and electrophysiological studies that provide new clues into the function of Shanks and pave the way for the discovery of new therapeutic drugs targeted to treat patients with SHANK mutations and also patients affected by other neurodevelopmental and neuropsychiatric disorders. Shank/ProSAP proteins are essential to synaptic formation, development, and function. Mutations in the family of SHANK genes are strongly associated with autism spectrum disorders (ASD) and other neurodevelopmental and neuropsychiatric disorders, such as intellectual disability (ID), and schizophrenia (SCZ). With this review we want to summarize the major genetic, molecular, behavior and electrophysiological studies that provide new clues into the function of Shanks and pave the way for the discovery of new therapeutic drugs targeted to treat patients with SHANK mutations. © 2015 International Society for Neurochemistry.

  15. Synapse geometry and receptor dynamics modulate synaptic strength.

    Directory of Open Access Journals (Sweden)

    Dominik Freche

    Full Text Available Synaptic transmission relies on several processes, such as the location of a released vesicle, the number and type of receptors, trafficking between the postsynaptic density (PSD and extrasynaptic compartment, as well as the synapse organization. To study the impact of these parameters on excitatory synaptic transmission, we present a computational model for the fast AMPA-receptor mediated synaptic current. We show that in addition to the vesicular release probability, due to variations in their release locations and the AMPAR distribution, the postsynaptic current amplitude has a large variance, making a synapse an intrinsic unreliable device. We use our model to examine our experimental data recorded from CA1 mice hippocampal slices to study the differences between mEPSC and evoked EPSC variance. The synaptic current but not the coefficient of variation is maximal when the active zone where vesicles are released is apposed to the PSD. Moreover, we find that for certain type of synapses, receptor trafficking can affect the magnitude of synaptic depression. Finally, we demonstrate that perisynaptic microdomains located outside the PSD impacts synaptic transmission by regulating the number of desensitized receptors and their trafficking to the PSD. We conclude that geometrical modifications, reorganization of the PSD or perisynaptic microdomains modulate synaptic strength, as the mechanisms underlying long-term plasticity.

  16. Cusps enable line attractors for neural computation

    International Nuclear Information System (INIS)

    Xiao, Zhuocheng; Zhang, Jiwei; Sornborger, Andrew T.; Tao, Louis

    2017-01-01

    Here, line attractors in neuronal networks have been suggested to be the basis of many brain functions, such as working memory, oculomotor control, head movement, locomotion, and sensory processing. In this paper, we make the connection between line attractors and pulse gating in feed-forward neuronal networks. In this context, because of their neutral stability along a one-dimensional manifold, line attractors are associated with a time-translational invariance that allows graded information to be propagated from one neuronal population to the next. To understand how pulse-gating manifests itself in a high-dimensional, nonlinear, feedforward integrate-and-fire network, we use a Fokker-Planck approach to analyze system dynamics. We make a connection between pulse-gated propagation in the Fokker-Planck and population-averaged mean-field (firing rate) models, and then identify an approximate line attractor in state space as the essential structure underlying graded information propagation. An analysis of the line attractor shows that it consists of three fixed points: a central saddle with an unstable manifold along the line and stable manifolds orthogonal to the line, which is surrounded on either side by stable fixed points. Along the manifold defined by the fixed points, slow dynamics give rise to a ghost. We show that this line attractor arises at a cusp catastrophe, where a fold bifurcation develops as a function of synaptic noise; and that the ghost dynamics near the fold of the cusp underly the robustness of the line attractor. Understanding the dynamical aspects of this cusp catastrophe allows us to show how line attractors can persist in biologically realistic neuronal networks and how the interplay of pulse gating, synaptic coupling, and neuronal stochasticity can be used to enable attracting one-dimensional manifolds and, thus, dynamically control the processing of graded information.

  17. Cusps enable line attractors for neural computation

    Science.gov (United States)

    Xiao, Zhuocheng; Zhang, Jiwei; Sornborger, Andrew T.; Tao, Louis

    2017-11-01

    Line attractors in neuronal networks have been suggested to be the basis of many brain functions, such as working memory, oculomotor control, head movement, locomotion, and sensory processing. In this paper, we make the connection between line attractors and pulse gating in feed-forward neuronal networks. In this context, because of their neutral stability along a one-dimensional manifold, line attractors are associated with a time-translational invariance that allows graded information to be propagated from one neuronal population to the next. To understand how pulse-gating manifests itself in a high-dimensional, nonlinear, feedforward integrate-and-fire network, we use a Fokker-Planck approach to analyze system dynamics. We make a connection between pulse-gated propagation in the Fokker-Planck and population-averaged mean-field (firing rate) models, and then identify an approximate line attractor in state space as the essential structure underlying graded information propagation. An analysis of the line attractor shows that it consists of three fixed points: a central saddle with an unstable manifold along the line and stable manifolds orthogonal to the line, which is surrounded on either side by stable fixed points. Along the manifold defined by the fixed points, slow dynamics give rise to a ghost. We show that this line attractor arises at a cusp catastrophe, where a fold bifurcation develops as a function of synaptic noise; and that the ghost dynamics near the fold of the cusp underly the robustness of the line attractor. Understanding the dynamical aspects of this cusp catastrophe allows us to show how line attractors can persist in biologically realistic neuronal networks and how the interplay of pulse gating, synaptic coupling, and neuronal stochasticity can be used to enable attracting one-dimensional manifolds and, thus, dynamically control the processing of graded information.

  18. A Voltage Mode Memristor Bridge Synaptic Circuit with Memristor Emulators

    Directory of Open Access Journals (Sweden)

    Leon Chua

    2012-03-01

    Full Text Available A memristor bridge neural circuit which is able to perform signed synaptic weighting was proposed in our previous study, where the synaptic operation was verified via software simulation of the mathematical model of the HP memristor. This study is an extension of the previous work advancing toward the circuit implementation where the architecture of the memristor bridge synapse is built with memristor emulator circuits. In addition, a simple neural network which performs both synaptic weighting and summation is built by combining memristor emulators-based synapses and differential amplifier circuits. The feasibility of the memristor bridge neural circuit is verified via SPICE simulations.

  19. The Nordic Housing Enabler

    DEFF Research Database (Denmark)

    Helle, Tina; Slaug, Bjørn; Brandt, Åse

    2010-01-01

    This study addresses development of a content valid cross-Nordic version of the Housing Enabler and investigation of its inter-rater reliability when used in occupational therapy rating situations, involving occupational therapists, clients and their home environments. The instrument was translated...... from the original Swedish version of the Housing Enabler, and adapted according to accessibility norms and guidelines for housing design in Sweden, Denmark, Finland and Iceland. This iterative process involved occupational therapists, architects, building engineers and professional translators......, resulting in the Nordic Housing Enabler. For reliability testing, the sampling strategy and data collection procedures used were the same in all countries. Twenty voluntary occupational therapists, pair-wise but independently from each other, collected data from 106 cases by means of the Nordic Housing...

  20. Pilot project as enabler?

    DEFF Research Database (Denmark)

    Neisig, Margit; Glimø, Helle; Holm, Catrine Granzow

    This article deals with a systemic perspective on transition. The field of study addressed is a pilot project as enabler of transition in a highly complex polycentric context. From a Luhmannian systemic approach, a framework is created to understand and address barriers of change occurred using...... pilot projects as enabler of transition. Aspects of how to create trust and deal with distrust during a transition are addressed. The transition in focus is the concept of New Public Management and how it is applied in the management of the Employment Service in Denmark. The transition regards...

  1. A central pattern generator producing alternative outputs: pattern, strength, and dynamics of premotor synaptic input to leech heart motor neurons.

    Science.gov (United States)

    Norris, Brian J; Weaver, Adam L; Wenning, Angela; García, Paul S; Calabrese, Ronald L

    2007-11-01

    The central pattern generator (CPG) for heartbeat in medicinal leeches consists of seven identified pairs of segmental heart interneurons and one unidentified pair. Four of the identified pairs and the unidentified pair of interneurons make inhibitory synaptic connections with segmental heart motor neurons. The CPG produces a side-to-side asymmetric pattern of intersegmental coordination among ipsilateral premotor interneurons corresponding to a similarly asymmetric fictive motor pattern in heart motor neurons, and asymmetric constriction pattern of the two tubular hearts, synchronous and peristaltic. Using extracellular recordings from premotor interneurons and voltage-clamp recordings of ipsilateral segmental motor neurons in 69 isolated nerve cords, we assessed the strength and dynamics of premotor inhibitory synaptic output onto the entire ensemble of heart motor neurons and the associated conduction delays in both coordination modes. We conclude that premotor interneurons establish a stereotypical pattern of intersegmental synaptic connectivity, strengths, and dynamics that is invariant across coordination modes, despite wide variations among preparations. These data coupled with a previous description of the temporal pattern of premotor interneuron activity and relative phasing of motor neuron activity in the two coordination modes enable a direct assessment of how premotor interneurons through their temporal pattern of activity and their spatial pattern of synaptic connectivity, strengths, and dynamics coordinate segmental motor neurons into a functional pattern of activity.

  2. The Locus Coeruleus–Norepinephrine System Mediates Empathy for Pain through Selective Up-Regulation of P2X3 Receptor in Dorsal Root Ganglia in Rats

    Directory of Open Access Journals (Sweden)

    Yun-Fei Lü

    2017-09-01

    Full Text Available Empathy for pain (vicariously felt pain, an ability to feel, recognize, understand and share the painful emotions of others, has been gradually accepted to be a common identity in both humans and rodents, however, the underlying neural and molecular mechanisms are largely unknown. Recently, we have developed a rat model of empathy for pain in which pain can be transferred from a cagemate demonstrator (CD in pain to a naïve cagemate observer (CO after 30 min dyadic priming social interaction. The naïve CO rats display both mechanical pain hypersensitivity (hyperalgesia and enhanced spinal nociception. Chemical lesions of bilateral medial prefrontal cortex (mPFC abolish the empathic pain response completely, suggesting existence of a top-down facilitation system in production of empathy for pain. However, the social transfer of pain was not observed in non-cagemate observer (NCO after dyadic social interaction with a non-cagemate demonstrator (NCD in pain. Here we showed that dyadic social interaction with a painful CD resulted in elevation of circulating norepinephrine (NE and increased neuronal activity in the locus coeruleus (LC in the CO rats. Meanwhile, CO rats also had over-expression of P2X3, but not TRPV1, in the dorsal root ganglia (DRG. Chemical lesion of the LC-NE neurons by systemic DSP-4 and pharmacological inhibition of central synaptic release of NE by clonidine completely abolished increase in circulating NE and P2X3 receptor expression, as well as the sympathetically-maintained development of empathic mechanical hyperalgesia. However, in the NCO rats, neither the LC-NE neuronal activity nor the P2X3 receptor expression was altered after dyadic social interaction with a painful NCD although the circulating corticosterone and NE were elevated. Finally, in the periphery, both P2X3 receptor and α1 adrenergic receptor were found to be involved in the development of empathic mechanical hyperalgesia. Taken together with our previous

  3. Enabling distributed collaborative science

    DEFF Research Database (Denmark)

    Hudson, T.; Sonnenwald, Diane H.; Maglaughlin, K.

    2000-01-01

    To enable collaboration over distance, a collaborative environment that uses a specialized scientific instrument called a nanoManipulator is evaluated. The nanoManipulator incorporates visualization and force feedback technology to allow scientists to see, feel, and modify biological samples bein...

  4. The Nordic Housing Enabler

    DEFF Research Database (Denmark)

    Helle, T.; Nygren, C.; Slaug, B.

    2014-01-01

    This study addresses development of a content-valid cross-Nordic version of the Housing Enabler and investigation of its inter-rater reliability when used in occupational therapy rating situations, involving occupational therapists, clients, and their home environments. The instrument was transla......This study addresses development of a content-valid cross-Nordic version of the Housing Enabler and investigation of its inter-rater reliability when used in occupational therapy rating situations, involving occupational therapists, clients, and their home environments. The instrument...... was translated from the original Swedish version of the Housing Enabler, and adapted according to accessibility norms and guidelines for housing design in Sweden, Denmark, Finland, and Iceland. This iterative process involved occupational therapists, architects, building engineers, and professional translators......, resulting in the Nordic Housing Enabler. For reliability testing, the sampling strategy and data collection procedures used were the same in all countries. Twenty voluntary occupational therapists, pair-wise but independently of each other, collected data from 106 cases by means of the Nordic Housing...

  5. A presynaptic role for PKA in synaptic tagging and memory

    NARCIS (Netherlands)

    Park, Alan Jung; Havekes, Robbert; Choi, Jennifer H K; Luczak, Vincent; Nie, Ting; Huang, Ted; Abel, Ted

    2014-01-01

    Protein kinase A (PKA) and other signaling molecules are spatially restricted within neurons by A-kinase anchoring proteins (AKAPs). Although studies on compartmentalized PKA signaling have focused on postsynaptic mechanisms, presynaptically anchored PKA may contribute to synaptic plasticity and

  6. Memristor-based neural networks: Synaptic versus neuronal stochasticity

    KAUST Repository

    Naous, Rawan; Alshedivat, Maruan; Neftci, Emre; Cauwenberghs, Gert; Salama, Khaled N.

    2016-01-01

    In neuromorphic circuits, stochasticity in the cortex can be mapped into the synaptic or neuronal components. The hardware emulation of these stochastic neural networks are currently being extensively studied using resistive memories or memristors

  7. Neuro-inspired computing using resistive synaptic devices

    CERN Document Server

    2017-01-01

    This book summarizes the recent breakthroughs in hardware implementation of neuro-inspired computing using resistive synaptic devices. The authors describe how two-terminal solid-state resistive memories can emulate synaptic weights in a neural network. Readers will benefit from state-of-the-art summaries of resistive synaptic devices, from the individual cell characteristics to the large-scale array integration. This book also discusses peripheral neuron circuits design challenges and design strategies. Finally, the authors describe the impact of device non-ideal properties (e.g. noise, variation, yield) and their impact on the learning performance at the system-level, using a device-algorithm co-design methodology. • Provides single-source reference to recent breakthroughs in resistive synaptic devices, not only at individual cell-level, but also at integrated array-level; • Includes detailed discussion of the peripheral circuits and array architecture design of the neuro-crossbar system; • Focuses on...

  8. Learning and Memory, Part II: Molecular Mechanisms of Synaptic Plasticity

    Science.gov (United States)

    Lombroso, Paul; Ogren, Marilee

    2009-01-01

    The molecular events that are responsible for strengthening synaptic connections and how these are linked to memory and learning are discussed. The laboratory preparations that allow the investigation of these events are also described.

  9. Multistate Resistive Switching Memory for Synaptic Memory Applications

    KAUST Repository

    Hota, Mrinal Kanti; Hedhili, Mohamed N.; Wehbe, Nimer; McLachlan, Martyn A.; Alshareef, Husam N.

    2016-01-01

    memory performance is observed. Conventional synaptic operation in terms of potentiation, depression plasticity, and Ebbinghaus forgetting process are also studied. The memory mechanism is shown to originate from the migration of the oxygen vacancies

  10. Binocular Rivalry in a Competitive Neural Network with Synaptic Depression

    KAUST Repository

    Kilpatrick, Zachary P.; Bressloff, Paul C.

    2010-01-01

    We study binocular rivalry in a competitive neural network with synaptic depression. In particular, we consider two coupled hypercolums within primary visual cortex (V1), representing orientation selective cells responding to either left or right

  11. Synaptic Control of Secretory Trafficking in Dendrites

    Directory of Open Access Journals (Sweden)

    Cyril Hanus

    2014-06-01

    Full Text Available Localized signaling in neuronal dendrites requires tight spatial control of membrane composition. Upon initial synthesis, nascent secretory cargo in dendrites exits the endoplasmic reticulum (ER from local zones of ER complexity that are spatially coupled to post-ER compartments. Although newly synthesized membrane proteins can be processed locally, the mechanisms that control the spatial range of secretory cargo transport in dendritic segments are unknown. Here, we monitored the dynamics of nascent membrane proteins in dendritic post-ER compartments under regimes of low or increased neuronal activity. In response to activity blockade, post-ER carriers are highly mobile and are transported over long distances. Conversely, increasing synaptic activity dramatically restricts the spatial scale of post-ER trafficking along dendrites. This activity-induced confinement of secretory cargo requires site-specific phosphorylation of the kinesin motor KIF17 by Ca2+/calmodulin-dependent protein kinases (CaMK. Thus, the length scales of early secretory trafficking in dendrites are tuned by activity-dependent regulation of microtubule-dependent transport.

  12. Design principles of electrical synaptic plasticity.

    Science.gov (United States)

    O'Brien, John

    2017-09-08

    Essentially all animals with nervous systems utilize electrical synapses as a core element of communication. Electrical synapses, formed by gap junctions between neurons, provide rapid, bidirectional communication that accomplishes tasks distinct from and complementary to chemical synapses. These include coordination of neuron activity, suppression of voltage noise, establishment of electrical pathways that define circuits, and modulation of high order network behavior. In keeping with the omnipresent demand to alter neural network function in order to respond to environmental cues and perform tasks, electrical synapses exhibit extensive plasticity. In some networks, this plasticity can have dramatic effects that completely remodel circuits or remove the influence of certain cell types from networks. Electrical synaptic plasticity occurs on three distinct time scales, ranging from milliseconds to days, with different mechanisms accounting for each. This essay highlights principles that dictate the properties of electrical coupling within networks and the plasticity of the electrical synapses, drawing examples extensively from retinal networks. Copyright © 2017 The Author. Published by Elsevier B.V. All rights reserved.

  13. Epigenetic Basis of Neuronal and Synaptic Plasticity.

    Science.gov (United States)

    Karpova, Nina N; Sales, Amanda J; Joca, Samia R

    2017-01-01

    Neuronal network and plasticity change as a function of experience. Altered neural connectivity leads to distinct transcriptional programs of neuronal plasticity-related genes. The environmental challenges throughout life may promote long-lasting reprogramming of gene expression and the development of brain disorders. The modifications in neuronal epigenome mediate gene-environmental interactions and are required for activity-dependent regulation of neuronal differentiation, maturation and plasticity. Here, we highlight the latest advances in understanding the role of the main players of epigenetic machinery (DNA methylation and demethylation, histone modifications, chromatin-remodeling enzymes, transposons, and non-coding RNAs) in activity-dependent and long- term neural and synaptic plasticity. The review focuses on both the transcriptional and post-transcriptional regulation of gene expression levels, including the processes of promoter activation, alternative splicing, regulation of stability of gene transcripts by natural antisense RNAs, and alternative polyadenylation. Further, we discuss the epigenetic aspects of impaired neuronal plasticity and the pathogenesis of neurodevelopmental (Rett syndrome, Fragile X Syndrome, genomic imprinting disorders, schizophrenia, and others), stressrelated (mood disorders) and neurodegenerative Alzheimer's, Parkinson's and Huntington's disorders. The review also highlights the pharmacological compounds that modulate epigenetic programming of gene expression, the potential treatment strategies of discussed brain disorders, and the questions that should be addressed during the development of effective and safe approaches for the treatment of brain disorders.

  14. Cholesterol asymmetry in synaptic plasma membranes.

    Science.gov (United States)

    Wood, W Gibson; Igbavboa, Urule; Müller, Walter E; Eckert, Gunter P

    2011-03-01

    Lipids are essential for the structural and functional integrity of membranes. Membrane lipids are not randomly distributed but are localized in different domains. A common characteristic of these membrane domains is their association with cholesterol. Lipid rafts and caveolae are examples of cholesterol enriched domains, which have attracted keen interest. However, two other important cholesterol domains are the exofacial and cytofacial leaflets of the plasma membrane. The two leaflets that make up the bilayer differ in their fluidity, electrical charge, lipid distribution, and active sites of certain proteins. The synaptic plasma membrane (SPM) cytofacial leaflet contains over 85% of the total SPM cholesterol as compared with the exofacial leaflet. This asymmetric distribution of cholesterol is not fixed or immobile but can be modified by different conditions in vivo: (i) chronic ethanol consumption; (ii) statins; (iii) aging; and (iv) apoE isoform. Several potential candidates have been proposed as mechanisms involved in regulation of SPM cholesterol asymmetry: apoE, low-density lipoprotein receptor, sterol carrier protein-2, fatty acid binding proteins, polyunsaturated fatty acids, P-glycoprotein and caveolin-1. This review examines cholesterol asymmetry in SPM, potential mechanisms of regulation and impact on membrane structure and function. © 2011 The Authors. Journal of Neurochemistry © 2011 International Society for Neurochemistry.

  15. Reference intervals and variation for urinary epinephrine, norepinephrine and cortisol in healthy men and women in Denmark

    DEFF Research Database (Denmark)

    Hansen, Åse Marie; Garde, A H; Christensen, J M

    2001-01-01

    Reference intervals for urinary epinephrine, norepinephrine and cortisol in 120 healthy individuals performing their routine work were established according to the International Union of Pure and Applied Chemistry (IUPAC) and the International Federation of Clinical Chemistry and Laboratory...... Medicine (IFCC) for use in the risk assessment of exposure to occupational stress. Reference intervals were established for three different times of the day: in morning samples (05.45-07.15) the limit of detection (LOD) was 2.10 micromol epinephrine/mol creatinine (82 women) and 2.86 micromol epinephrine....../mol creatinine (37 men), and the reference interval was 3.6-29.1 micromol norepinephrine/mol creatinine and 2.3-52.8 micromol cortisol/mol creatinine (119 women and men); in afternoon samples (15.30-18.30) the reference interval was 0.64-10.8 micromol epinephrine/mol creatinine (82 women), 1.20-11.2 micromol...

  16. Reduced Synaptic Vesicle Recycling during Hypoxia in Cultured Cortical Neurons

    OpenAIRE

    Fedorovich, Sergei; Hofmeijer, Jeannette; van Putten, Michel Johannes Antonius Maria; le Feber, Jakob

    2017-01-01

    Improvement of neuronal recovery in the ischemic penumbra, an area around the core of a brain infarct with some remaining perfusion, has a large potential for the development of therapy against acute ischemic stroke. However, mechanisms that lead to either recovery or secondary damage in the penumbra largely remain unclear. Recent studies in cultured networks of cortical neurons showed that failure of synaptic transmission (referred to as synaptic failure) is a critical factor in the penumbra...

  17. Common mechanisms of synaptic plasticity in vertebrates and invertebrates

    Science.gov (United States)

    Glanzman, David L.

    2016-01-01

    Until recently, the literature on learning-related synaptic plasticity in invertebrates has been dominated by models assuming plasticity is mediated by presynaptic changes, whereas the vertebrate literature has been dominated by models assuming it is mediated by postsynaptic changes. Here I will argue that this situation does not reflect a biological reality and that, in fact, invertebrate and vertebrate nervous systems share a common set of mechanisms of synaptic plasticity. PMID:20152143

  18. Increased release of norepinephrine and dopamine from canine kidney during bilateral carotid occlusion

    International Nuclear Information System (INIS)

    Bradley, T.; Hjemdahl, P.; DiBona, G.F.

    1987-01-01

    The renal overflow of norepinephrine (NE) and dopamine (DA) to plasma from the innervated kidney was studied at rest and during sympathetic nervous system activation by bilateral carotid artery occlusion (BCO) in vagotomized dogs under barbiturate or barbiturate/nitrous oxide anesthesia. BCO elevated arterial pressure and the arterial plasma concentration of NE, DA, and epinephrine (Epi). Renal vascular resistance (renal arterial pressure kept constant) increased by 15 +/- 7% and the net renal venous outflows (renal veno-arterial concentration difference x renal plasma flow) of NE and DA were enhanced. To obtain more correct estimates of the renal contribution to the renal venous catecholamine outflow, they corrected for the renal extraction of arterial catecholamines, assessed as the extractions of [ 3 H]NE, [ 3 H]DA, or endogenous Epi. The [ 3 H]NE corrected renal NE overflow to plasma increased from 144 +/- 40 to 243 +/- 64 pmol-min -1 during BCO, which, when compared with a previous study of the [ 3 H]NE corrected renal NE overflow to plasma evoked by electrical renal nerve stimulation, corresponds to a 40% increase in nerve impulse frequency from ∼ 0.6 Hz. If the renal catecholamine extraction was not taken into account the effect of BCO was underestimated. The renal DA overflow to plasma was about one-fifth of the NE overflow both at rest and during BCO, indicating that there was no preferential activation of noradrenergic or putative dopaminergic nerves by BCO

  19. Abnormal norepinephrine clearance and adrenergic receptor sensitivity in idiopathic orthostatic intolerance

    Science.gov (United States)

    Jacob, G.; Shannon, J. R.; Costa, F.; Furlan, R.; Biaggioni, I.; Mosqueda-Garcia, R.; Robertson, R. M.; Robertson, D.

    1999-01-01

    BACKGROUND: Chronic orthostatic intolerance (OI) is characterized by symptoms of inadequate cerebral perfusion with standing, in the absence of significant orthostatic hypotension. A heart rate increase of >/=30 bpm is typical. Possible underlying pathophysiologies include hypovolemia, partial dysautonomia, or a primary hyperadrenergic state. We tested the hypothesis that patients with OI have functional abnormalities in autonomic neurons regulating cardiovascular responses. METHODS AND RESULTS: Thirteen patients with chronic OI and 10 control subjects underwent a battery of autonomic tests. Systemic norepinephrine (NE) kinetics were determined with the patients supine and standing before and after tyramine administration. In addition, baroreflex sensitivity, hemodynamic responses to bolus injections of adrenergic agonists, and intrinsic heart rate were determined. Resting supine NE spillover and clearance were similar in both groups. With standing, patients had a greater decrease in NE clearance than control subjects (55+/-5% versus 30+/-7%, Pheart rate 25 bpm was lower in patients than in control subjects (0.5+/-0.05 versus 1.0+/-0.1 microg, Pheart rate was similar in both groups. CONCLUSIONS: The decreased NE clearance with standing, resistance to the NE-releasing effect of tyramine, and increased sensitivity to adrenergic agonists demonstrate dramatically disordered sympathetic cardiovascular regulation in patients with chronic OI.

  20. Modulation of attentional inhibition by norepinephrine and cortisol after psychological stress.

    Science.gov (United States)

    Skosnik, P D; Chatterton, R T; Swisher, T; Park, S

    2000-04-01

    Two of the most salient physiological responses to stress are increased norepinephrine (NE) and cortisol (CORT) activities. However, it is unclear how these neurochemical events affect cognition, especially attention. We examined the effects of mild psychological stress on selective attention, as assessed by the negative priming (NP) paradigm. Salivary measures of the stress hormone CORT and alpha-amylase (a correlate of NE) were assayed to probe the relationship between the stress response and attentional inhibition. Healthy subjects (N = 20) engaged in the attention task, which was then followed by 15 min of a stressful video game before a return to the attentional task. Baseline saliva samples were obtained before the experiment began, 1 min after the video-game stressor, and 20 min post-stress. Subjects showed a significant reduction in NP and a decrease in reaction time (RT) after the video game. Moreover, alpha-amylase levels increased significantly after the stressor, indicating the role of NE in the acute stress response. While CORT levels remained unchanged after stress, CORT correlated significantly with both NP scores and RT after the stressor. These results imply that mild psychological stress can significantly alter attentional processes. Given the increase in alpha-amylase and the correlation between attention and CORT after stress, it seems likely that attentional processes are under tight control by brain systems which mediate the fight-or-flight response.

  1. Norepinephrine regulates cocaine-primed reinstatement via α1-adrenergic receptors in the medial prefrontal cortex.

    Science.gov (United States)

    Schmidt, Karl T; Schroeder, Jason P; Foster, Stephanie L; Squires, Katherine; Smith, Brilee M; Pitts, Elizabeth G; Epstein, Michael P; Weinshenker, David

    2017-06-01

    Drug-primed reinstatement of cocaine seeking in rats is thought to reflect relapse-like behavior and is mediated by the integration of signals from mesocorticolimbic dopaminergic projections and corticostriatal glutamatergic innervation. Cocaine-primed reinstatement can also be attenuated by systemic administration of dopamine β-hydroxylase (DBH) inhibitors, which prevent norepinephrine (NE) synthesis, or by α1-adrenergic receptor (α1AR) antagonists, indicating functional modulation by the noradrenergic system. In the present study, we sought to further discern the role of NE in cocaine-seeking behavior by determining whether α1AR activation can induce reinstatement on its own or is sufficient to permit cocaine-primed reinstatement in the absence of all other AR signaling, and identifying the neuroanatomical substrate within the mesocorticolimbic reward system harboring the critical α1ARs. We found that while intracerebroventricular infusion of the α1AR agonist phenylephrine did not induce reinstatement on its own, it did overcome the blockade of cocaine-primed reinstatement by the DBH inhibitor nepicastat. Furthermore, administration of the α1AR antagonist terazosin in the medial prefrontal cortex (mPFC), but not the ventral tegmental area (VTA) or nucleus accumbens (NAc) shell, attenuated cocaine-primed reinstatement. Combined, these data indicate that α1AR activation in the mPFC is required for cocaine-primed reinstatement, and suggest that α1AR antagonists merit further investigation as pharmacotherapies for cocaine dependence. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Norepinephrine metabolism in man using deuterium labeling: turnover 4-hydroxy-3-methoxymandelic acid

    Energy Technology Data Exchange (ETDEWEB)

    Mardh, G.; Sjoequist, B.; Anggard, E.

    1982-06-01

    4-Hydroxy-3-methoxymandelic acid (HMMA; VMA) labeled with three deuterium atoms was used to study the turnover and fate of HMMA following intravenous injection. Five healthy men were given a pulse dose of 5.0 mumol of labeled HMMA. Plasma and urinary levels of both endogenous and labeled HMMA were subsequently followed by gas chromatography-mass spectrometry using selected ion detection. The kinetic parameters were determined both with and without compensation for the pool expansion caused by the injection of labeled HMMA. The urinary recovery of labeled HMMA was 85 +/- 10% (mean +/- SD). No conversion of HMMA to 4-hydroxy-3-methoxyphenyl glycol (HMPG) occurred. The biological half-life of HMMA was 0.54 +/- 0.22 h. The apparent volume of distribution was 0.36 +/- 0.11 L/kg. The production rate or body turnover was 1.27 +/- 0.51 mumol HMMA/h and urinary excretion rate was 0.82 +/- 0.22 mumol/h. These results show that HMMA is turnover over rapidly in a relatively small volume of distribution and that, unlike HMPG, it is an end metabolite of norepinephrine in man.

  3. A locus coeruleus-norepinephrine account of individual differences in working memory capacity and attention control.

    Science.gov (United States)

    Unsworth, Nash; Robison, Matthew K

    2017-08-01

    Studies examining individual differences in working memory capacity (WMC) have suggested that low WMC individuals have particular deficits in attention control processes compared to high WMC individuals. In the current article we suggest that part of the WMC-attention control relation is due to variation in the functioning of the locus coeruleus-norepinephrine system (LC-NE). Specifically, we suggest that because of dysregulation of LC-NE functioning, the fronto-parietal control network for low WMC individuals is only weakly activated, resulting in greater default-mode network activity (and greater mind-wandering) for low WMC individuals compared to high WMC individuals. This results in disrupted attention control and overall more erratic performance (more lapses of attention) for low WMC individuals than for high WMC individuals. This framework is used to examine previous studies of individual differences in WMC and attention control, and new evidence is examined on the basis of predictions of the framework to pupillary responses as an indirect marker of LC-NE functioning.

  4. Effects of estradiol on norepinephrine and prostaglandin efflux in medial basal hypothalamus of ovariectomized rats

    International Nuclear Information System (INIS)

    Cardinali, D.P.; Fernandez Pardal, J.; Gimeno, M.F.; Gimeno, A.L.

    1982-01-01

    The spontaneous and K + -stimulated efflux of norepinephrine (NE) and the release of PGE 2 and PGF 2 α were examined in medial basal hypothalamus (MBH) of ovariectomized rats killed before and during the LH release that follows estradiol treatment. As compared to vehicle-treated, ovariectomized rats, estradiol-primed rats exhibited a 60% more increase in K + -stimulated 3 H-overflow of MBH slices preloaded with 3 H-NE at morning hours (1000 hours). Estradiol treatment did not result in further increase of K + -induced 3 H release from MBH slices at the time of LH release (1700 hours), nor affected labelled NE release in occipital cortex slices. A significant difference between K + -stimulated NE release of vehicle-treated spayed rats killed at 1000 and 1700 hours was observed, the latter showing 54% more release upon stimulus. PGE 2 efflux was time-dependent being highest at the evening in both vehicle- and estradiol-treated animals. The MBH of estrogenized rats released significantly more PGE 2 at the evening as compared to the controls. The release of PGF 2 α remained essentially unchanged regardless of estradiol treatment or time of day. The present results offer additional support to the involvement of MBH catecholamines and prostaglandins in the mechanism of LH secretion in the rat. (author)

  5. Sex differences in the locus coeruleus-norepinephrine system and its regulation by stress.

    Science.gov (United States)

    Bangasser, Debra A; Wiersielis, Kimberly R; Khantsis, Sabina

    2016-06-15

    Women are more likely than men to suffer from post-traumatic stress disorder (PTSD) and major depression. In addition to their sex bias, these disorders share stress as an etiological factor and hyperarousal as a symptom. Thus, sex differences in brain arousal systems and their regulation by stress could help explain increased vulnerability to these disorders in women. Here we review preclinical studies that have identified sex differences in the locus coeruleus (LC)-norepinephrine (NE) arousal system. First, we detail how structural sex differences in the LC can bias females towards increased arousal in response to emotional events. Second, we highlight studies demonstrating that estrogen can increase NE in LC target regions by enhancing the capacity for NE synthesis, while reducing NE degradation, potentially increasing arousal in females. Third, we review data revealing how sex differences in the stress receptor, corticotropin releasing factor 1 (CRF1), can increase LC neuronal sensitivity to CRF in females compared to males. This effect could translate into hyperarousal in women under conditions of CRF hypersecretion that occur in PTSD and depression. The implications of these sex differences for the treatment of stress-related psychiatric disorders are discussed. Moreover, the value of using information regarding biological sex differences to aid in the development of novel pharmacotherapies to better treat men and women with PTSD and depression is also highlighted. This article is part of a Special Issue entitled SI: Noradrenergic System. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Plasma levels of norepinephrine during the periovulatory period in normal women

    International Nuclear Information System (INIS)

    Badano, A.R.; Nagle, C.A.; Casas, P.R.F.; Miechi, H.; Mirkin, A.; Turner, D.E.; Aparicio, N.; Rosner, J.M.

    1978-01-01

    Eleven normally cycling women in whom laparotomy was indicated for benign gynecologic pathology were studied. Surgery was performed on day 0 (expected day of ovulation). Blood samples were drawn daily from day -8 to day -4, and every 8 hours from day -3 to day +2; estradiol (E 2 ), progesterone (P), norepinephrine (NE), and LH were determined by RIA. Ovulation was certified by ovarian visualization and biopsy during laparotomy. In nine ovulatory patients mean E 2 peak was found 48 hours before LH peak. Mean NE levels showed minimal variations until 48 hours before LH peak; 8 hours after E 2 peak mean NE values increased significantly, fell 8 hours later, and rose immediately again, reaching maximal levels 24 hours after E 2 peak. These values remained high until 16 hours before the LH peak and decreased gradully, thereafter reaching basal levels 32 hours after LH peak. Two anovulatory patients showed an atypical pattern of ovarian steroids and LH secretion and NE showed large variations without any correlation with estradiol or LH levels. This study confirms previous findings in women and experimental work in animals regarding the existence of a noradrenergic trigger mechanism to the LH ovulatory discharge

  7. A microelectrode array electrodeposited with reduced graphene oxide and Pt nanoparticles for norepinephrine and electrophysiological recordings

    Science.gov (United States)

    Wang, Li; Song, Yilin; Zhang, Yu; Xu, Shengwei; Xu, Huiren; Wang, Mixia; Wang, Yang; Cai, Xinxia

    2017-11-01

    Norepinephrine (NE), a common neurotransmitter released by locus coeruleus neurons, plays an essential role in the communication mechanism of the mammalian nervous system. In this work, a microelectrode array (MEA) was fabricated by micro-electromechanical system (MEMS) technology to provide a rapid, sensitive and reliable method for the direct determination in NE dynamic secretion. To improve the electrical performance, the MEA was electrodeposited with the reduced graphene oxide and Pt nanoparticles (rGOPNps). rGOPNps-MEA was investigated using scanning electron microscopy, atomic force microscopy and electrochemical impedance spectroscopy, differential pulse voltammetry exhibited remarkably electrocatalytic properties towards NE. Calibration results showed a sensitivity of 1.03 nA µM-1 to NE with a detection limit of 0.08 µM. In Particular, the MEA was successfully used for measuring dynamic extracellular NE secretion from the locus coeruleus brain slice, as well as monitoring spike firing from the hippocampal brain slice. This fabricated device has potential in studies of spatially resolved delivery of trace neurochemicals and electrophysiological activities of a variety of biological tissues in vitro.

  8. Perinatal methadone exposure affects dopamine, norepinephrine, and serotonin in the weanling rat.

    Science.gov (United States)

    Robinson, S E; Maher, J R; Wallace, M J; Kunko, P M

    1997-01-01

    On gestational day 7 pregnant rats were implanted with osmotic minipumps containing either methadone hydrochloride (initial dose, 9 mg/kg/day) or sterile water. Their offspring were cross-fostered so that they were exposed to methadone prenatally and/or postnatally. On postnatal day 21, dopamine (DA), norepinephrine (NE), serotonin (5-HT), and their metabolites were analyzed. Perinatal methadone exposure disrupted dopaminergic, noradrenergic, and serotonergic activity in a brain region- and gender-specific fashion. The ratio of the DA metabolite 3,4-dihydroxyphenylacetic acid (DOPAC) to DA was reduced in the frontal cortex of males exposed to methadone postnatally. No effects of perinatal methadone exposure were observed on DA and DOPAC in the striatum. The ratio of 3-methoxy-4-hydroxyphenylglycol (MOPEG) to NE in the hippocampus was increased significantly in males exposed to methadone prenatally. Striatal and parietal cortical 5-hydroxyindoleacetic acid (5-HIAA), but not its ratio to 5-HT, was increased slightly in rats exposed to methadone postnatally. Although parietal cortical 5-HT, 5-HIAA, and 5-hydroxytryptophan were all affected by perinatal methadone exposure, the ratios of metabolite and precursor to 5-HT were not affected. Effects of methadone exposure appeared to depend upon the developmental stage at which exposure occurred and did not appear to result from the phenomenon of neonatal withdrawal. Changes in activity of these three neurotransmitter systems may contribute to the effect of perinatal methadone on the activity of other neurons, such as cholinergic neurons.

  9. The emerging role of norepinephrine in cognitive dysfunctions of Parkinson’s disease

    Directory of Open Access Journals (Sweden)

    Elena eVazey

    2012-07-01

    Full Text Available Parkinson’s disease (PD is the second most common neurodegenerative disorder, affecting 1% of the population over age 60. In those patients cognitive dysfunction is a persistent issue that impairs quality of life and productivity. Neuropathological studies demonstrate significant damage in brain regions outside the nigral dopamine (DA system, including early degeneration of locus coeruleus norepinephrine (LC-NE neurons, yet discussion of PD and treatment focus has remained dopaminergic-based. Motor symptoms benefit from DA replacement for many years, but other symptoms including several cognitive deficits continue unabated. Recent interest in non-DA substrates of PD highlights early involvement of LC-NE neurons and provides evidence for a prodromal phase, with cognitive disturbance, even in sporadic PD. We outline insights from basic research in LC-NE function to clinical and pathological evidence highlighting a role for NE in PD cognitive dysfunction. We propose that loss of LC-NE regulation, particularly in higher cortical regions, critically underlies certain cognitive dysfunctions in early PD. As a major unmet need for patients, research and use of NE drugs in PD may provide significant benefits for cognitive processing.

  10. Improved radioenzymatic assay for plasma norepinephrine using purified phenylethanolamine n-methyltransferase

    International Nuclear Information System (INIS)

    Bowsher, R.R.; Henry, D.P.

    1986-01-01

    Radioenzymatic assays have been developed for catecholamines using either catechol O-methyltransferase (COMT) or phenylethanolamine N-methyltransferase (PNMT). Assays using PNMT are specific for norepinephrine (NE) and require minimal manipulative effort but until now have been less sensitive than the more complex procedures using COMT. The authors report an improved purification scheme for bovine PNMT which has permitted development of an NE assay with dramatically improved sensitivity (0.5 pg), specificity and reproducibility (C.V. < 5%). PNMT was purified by sequential pH 5.0 treatment and dialysis and by column chromatographic procedures using DEAE-Sephacel, Sepharcryl S-200 and Phenyl-Boronate Agarose. Recovery of PNMT through the purification scheme was 50%, while blank recovery was <.001%. NE can be directly quantified in 25 ul of human plasma and an 80 tube assay can be completed within 4 h. The capillary to venous plasma NE gradient was examined in 8 normotensive male subjects. Capillary plasma (NE (211.2 +/- 61.3 pg/ml)) was lower than venous plasma NE (366.6 +/- 92.5 pg/ml) in all subjects (p < 0.005). This difference suggests that capillary (NE) may be a unique indicator of sympathetic nervous system activity in vivo. In conclusion, purification of PNMT has facilitated development of an improved radioenzymatic for NE with significantly improved sensitivity

  11. Norepinephrine signaling through β-adrenergic receptors is critical for expression of cocaine-induced anxiety

    Science.gov (United States)

    Schank, Jesse R.; Liles, L. Cameron; Weinshenker, David

    2008-01-01

    Background Cocaine is a widely abused psychostimulant that has both rewarding and aversive properties. While the mechanisms underlying cocaine’s rewarding effects have been studied extensively, less attention has been paid to the unpleasant behavioral states induced by cocaine, such as anxiety. Methods In this study we evaluated the performance of dopamine β-hydroxylase knockout (Dbh −/−) mice, which lack norepinephrine (NE), in the elevated plus maze (EPM) to examine the contribution of noradrenergic signaling to cocaine-induced anxiety. Results We found that cocaine dose-dependently increased anxiety-like behavior in control (Dbh +/−) mice, as measured by a decrease in open arm exploration. Dbh −/− mice had normal baseline performance in the EPM, but were completely resistant to the anxiogenic effects of cocaine. Cocaine-induced anxiety was also attenuated in Dbh +/− mice following administration of disulfiram, a DBH inhibitor. In experiments using specific adrenergic antagonists, we found that pretreatment with the β-adrenergic receptor antagonist propranolol blocked cocaine-induced anxiety-like behavior in Dbh +/− and wild-type C57BL6/J mice, while the α1 antagonist prazosin and the α2 antagonist yohimbine had no effect. Conclusions These results indicate that noradrenergic signaling via β-adrenergic receptors is required for cocaine-induced anxiety in mice. PMID:18083142

  12. Norepinephrine signaling through beta-adrenergic receptors is critical for expression of cocaine-induced anxiety.

    Science.gov (United States)

    Schank, Jesse R; Liles, L Cameron; Weinshenker, David

    2008-06-01

    Cocaine is a widely abused psychostimulant that has both rewarding and aversive properties. While the mechanisms underlying cocaine's rewarding effects have been studied extensively, less attention has been paid to the unpleasant behavioral states induced by cocaine, such as anxiety. In this study, we evaluated the performance of dopamine beta-hydroxylase knockout (Dbh -/-) mice, which lack norepinephrine (NE), in the elevated plus maze (EPM) to examine the contribution of noradrenergic signaling to cocaine-induced anxiety. We found that cocaine dose-dependently increased anxiety-like behavior in control (Dbh +/-) mice, as measured by a decrease in open arm exploration. The Dbh -/- mice had normal baseline performance in the EPM but were completely resistant to the anxiogenic effects of cocaine. Cocaine-induced anxiety was also attenuated in Dbh +/- mice following administration of disulfiram, a dopamine beta-hydroxylase (DBH) inhibitor. In experiments using specific adrenergic antagonists, we found that pretreatment with the beta-adrenergic receptor antagonist propranolol blocked cocaine-induced anxiety-like behavior in Dbh +/- and wild-type C57BL6/J mice, while the alpha(1) antagonist prazosin and the alpha(2) antagonist yohimbine had no effect. These results indicate that noradrenergic signaling via beta-adrenergic receptors is required for cocaine-induced anxiety in mice.

  13. Meningeal norepinephrine produces headache behaviors in rats via actions both on dural afferents and fibroblasts.

    Science.gov (United States)

    Wei, Xiaomei; Yan, Jin; Tillu, Dipti; Asiedu, Marina; Weinstein, Nicole; Melemedjian, Ohannes; Price, Theodore; Dussor, Gregory

    2015-10-01

    Stress is commonly reported to contribute to migraine although mechanisms by which this may occur are not fully known. The purpose of these studies was to examine whether norepinephrine (NE), the primary sympathetic efferent transmitter, acts on processes in the meninges that may contribute to the pain of migraine. NE was applied to rat dura using a behavioral model of headache. Primary cultures of rat trigeminal ganglia retrogradely labeled from the dura mater and of rat dural fibroblasts were prepared. Patch-clamp electrophysiology, Western blot, and ELISA were performed to examine the effects of NE. Conditioned media from NE-treated fibroblast cultures was applied to the dura using the behavioral headache model. Dural injection both of NE and media from NE-stimulated fibroblasts caused cutaneous facial and hindpaw allodynia in awake rats. NE application to cultured dural afferents increased action potential firing in response to current injections. Application of NE to dural fibroblasts increased phosphorylation of ERK and caused the release of interleukin-6 (IL-6). These data demonstrate that NE can contribute to pro-nociceptive signaling from the meninges via actions on dural afferents and dural fibroblasts. Together, these actions of NE may contribute to the headache phase of migraine. © International Headache Society 2015.

  14. Norepinephrine accumulation by the rat caudal artery in the presence of hypertensive plasma

    International Nuclear Information System (INIS)

    Freas, W.; Thompson, D.A.; Hart, J.L.; Muldoon, S.M.

    1986-01-01

    We have partially isolated endogenous factors from canine plasma which inhibit 3 H-norepinephrine (NE) accumulation by the canine saphenous vein. The purpose of this study is to determine if these circulating factors may account for the observed differences in 3 H-NE uptake by hypertensive and normotensive blood vessels. Three models of hypertension were examined in this study. Blood vessels were compared from SHR and WKY rats, deoxycorticosterone acetate (DOCA) and control rats, and reduced renal mass (RRM) and control rats. There was no significant difference in 3 H-NE accumulation between blood vessels obtained from RRM and paired control rats. However, both the SHR and DOCA hypertensive caudal arteries and aorta accumulated significantly more 3 H-NE than their corresponding control tissues. There was not a significant change in 3 H-NE accumulation between hypertensive and control vena cava and mesenteric arteries. Normotensive and hypertensive plasma inhibited 3 H-NE accumulation by the rat caudal artery. However, there was not a correlation between blood pressure of plasma donor rats and accumulation of 3 H-NE. Therefore, although there are differences in 3 H-NE accumulation between hypertensive and normotensive blood vessels, plasma does not contain a factor responsible for this observed difference

  15. External and internal standards in the single-isotope derivative (radioenzymatic) measurement of plasma norepinephrine and epinephrine

    International Nuclear Information System (INIS)

    Shah, S.D.; Clutter, W.E.; Cryer, P.E.

    1985-01-01

    In plasma from normal humans (n = 9, 35 samples) and from patients with diabetes mellitus (n = 12, 24 samples) single-isotope derivative (radioenzymatic) plasma norepinephrine and epinephrine concentrations calculated from external standard curves constructed in a normal plasma pool were identical to those calculated from internal standards added to an aliquot of each plasma sample. In plasma from patients with end-stage renal failure receiving long-term dialysis (n = 34, 109 samples), competitive catechol-O-methyltransferase (COMT) inhibitory activity resulted in a systematic error when external standards in a normal plasma pool were used, as reported previously; values so calculated averaged 21% (+/- 12%, SD) lower than those calculated from internal standards. However, when external standard curves were constructed in plasma from a given patient with renal failure and used to calculate that patient's values, or in a renal failure plasma pool and used to calculate all renal failure values, norepinephrine and epinephrine concentrations were not significantly different from those calculated from internal standards. We conclude: (1) External standard curves constructed in plasma from a given patient with renal failure can be used to measure norepinephrine and epinephrine in plasma from that patient; further, external standards in a renal failure plasma pool can be used for assays in patients with end-stage renal failure receiving long-term dialysis. (2) Major COMT inhibitory activity is not present commonly if samples from patients with renal failure are excluded. Thus, it would appear that external standard curves constructed in normal plasma can be used to measure norepinephrine and epinephrine precisely in samples from persons who do not have renal failure

  16. Influence of chronic captopril treatment on norepinephrine-induced vasoconstriction in SHR and WKY : In vivo study

    Czech Academy of Sciences Publication Activity Database

    Pintérová, Mária; Kuneš, Jaroslav; Dobešová, Zdenka; Zicha, Josef

    2008-01-01

    Roč. 26, Suppl.1 (2008), S174-S174 ISSN 0263-6352. [Scientific Meeting International Society of Hypertension /22./ , Scientific Meeting European Society of Hypertension /18./. 14.06.2008-19.06.2008, Berlin] Institutional research plan: CEZ:AV0Z50110509 Keywords : cpo1 * captopril teratment * norepinephrine-induced vasoconstriction * SHR and WKY Subject RIV: FA - Cardiovascular Diseases incl. Cardiotharic Surgery

  17. Synaptic Contacts Enhance Cell-to-Cell Tau Pathology Propagation.

    Science.gov (United States)

    Calafate, Sara; Buist, Arjan; Miskiewicz, Katarzyna; Vijayan, Vinoy; Daneels, Guy; de Strooper, Bart; de Wit, Joris; Verstreken, Patrik; Moechars, Diederik

    2015-05-26

    Accumulation of insoluble Tau protein aggregates and stereotypical propagation of Tau pathology through the brain are common hallmarks of tauopathies, including Alzheimer's disease (AD). Propagation of Tau pathology appears to occur along connected neurons, but whether synaptic contacts between neurons are facilitating propagation has not been demonstrated. Using quantitative in vitro models, we demonstrate that, in parallel to non-synaptic mechanisms, synapses, but not merely the close distance between the cells, enhance the propagation of Tau pathology between acceptor hippocampal neurons and Tau donor cells. Similarly, in an artificial neuronal network using microfluidic devices, synapses and synaptic activity are promoting neuronal Tau pathology propagation in parallel to the non-synaptic mechanisms. Our work indicates that the physical presence of synaptic contacts between neurons facilitate Tau pathology propagation. These findings can have implications for synaptic repair therapies, which may turn out to have adverse effects by promoting propagation of Tau pathology. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  18. BDNF-induced local protein synthesis and synaptic plasticity.

    Science.gov (United States)

    Leal, Graciano; Comprido, Diogo; Duarte, Carlos B

    2014-01-01

    Brain-derived neurotrophic factor (BDNF) is an important regulator of synaptic transmission and long-term potentiation (LTP) in the hippocampus and in other brain regions, playing a role in the formation of certain forms of memory. The effects of BDNF in LTP are mediated by TrkB (tropomyosin-related kinase B) receptors, which are known to be coupled to the activation of the Ras/ERK, phosphatidylinositol 3-kinase/Akt and phospholipase C-γ (PLC-γ) pathways. The role of BDNF in LTP is best studied in the hippocampus, where the neurotrophin acts at pre- and post-synaptic levels. Recent studies have shown that BDNF regulates the transport of mRNAs along dendrites and their translation at the synapse, by modulating the initiation and elongation phases of protein synthesis, and by acting on specific miRNAs. Furthermore, the effect of BDNF on transcription regulation may further contribute to long-term changes in the synaptic proteome. In this review we discuss the recent progress in understanding the mechanisms contributing to the short- and long-term regulation of the synaptic proteome by BDNF, and the role in synaptic plasticity, which is likely to influence learning and memory formation. This article is part of the Special Issue entitled 'BDNF Regulation of Synaptic Structure, Function, and Plasticity'. Copyright © 2013 Elsevier Ltd. All rights reserved.

  19. Self-organised criticality via retro-synaptic signals

    Science.gov (United States)

    Hernandez-Urbina, Victor; Herrmann, J. Michael

    2016-12-01

    The brain is a complex system par excellence. In the last decade the observation of neuronal avalanches in neocortical circuits suggested the presence of self-organised criticality in brain networks. The occurrence of this type of dynamics implies several benefits to neural computation. However, the mechanisms that give rise to critical behaviour in these systems, and how they interact with other neuronal processes such as synaptic plasticity are not fully understood. In this paper, we present a long-term plasticity rule based on retro-synaptic signals that allows the system to reach a critical state in which clusters of activity are distributed as a power-law, among other observables. Our synaptic plasticity rule coexists with other synaptic mechanisms such as spike-timing-dependent plasticity, which implies that the resulting synaptic modulation captures not only the temporal correlations between spiking times of pre- and post-synaptic units, which has been suggested as requirement for learning and memory in neural systems, but also drives the system to a state of optimal neural information processing.

  20. SYNAPTIC DEPRESSION IN DEEP NEURAL NETWORKS FOR SPEECH PROCESSING.

    Science.gov (United States)

    Zhang, Wenhao; Li, Hanyu; Yang, Minda; Mesgarani, Nima

    2016-03-01

    A characteristic property of biological neurons is their ability to dynamically change the synaptic efficacy in response to variable input conditions. This mechanism, known as synaptic depression, significantly contributes to the formation of normalized representation of speech features. Synaptic depression also contributes to the robust performance of biological systems. In this paper, we describe how synaptic depression can be modeled and incorporated into deep neural network architectures to improve their generalization ability. We observed that when synaptic depression is added to the hidden layers of a neural network, it reduces the effect of changing background activity in the node activations. In addition, we show that when synaptic depression is included in a deep neural network trained for phoneme classification, the performance of the network improves under noisy conditions not included in the training phase. Our results suggest that more complete neuron models may further reduce the gap between the biological performance and artificial computing, resulting in networks that better generalize to novel signal conditions.

  1. Spatially enabled land administration

    DEFF Research Database (Denmark)

    Enemark, Stig

    2006-01-01

    enabling of land administration systems managing tenure, valuation, planning, and development will allow the information generated by these activities to be much more useful. Also, the services available to private and public sectors and to community organisations should commensurably improve. Knowledge....... In other words: Good governance and sustainable development is not attainable without sound land administration or - more broadly – sound land management. The paper presents a land management vision that incorporates the benefits of ICT enabled land administration functions. The idea is that spatial...... the communication between administrative systems and also establish more reliable data due to the use the original data instead of copies. In Denmark, such governmental guidelines for a service-oriented ITarchitecture in support of e-government are recently adopted. Finally, the paper presents the role of FIG...

  2. Nordic Housing Enabler

    DEFF Research Database (Denmark)

    Helle, Tina; Brandt, Åse

    Development and reliability testing of the Nordic Housing Enabler – an instrument for accessibility assessment of the physical housing. Tina Helle & Åse Brandt University of Lund, Health Sciences, Faculty of Medicine (SE) and University College Northern Jutland, Occupational Therapy department (DK......). Danish Centre for Assistive Technology. Abstract. For decades, accessibility to the physical housing environment for people with functional limitations has been of interest politically, professionally and for the users. Guidelines and norms on accessible housing design have gradually been developed......, however, the built environment shows serious deficits when it comes to accessibility. This study addresses development of a content valid cross-Nordic version of the Housing Enabler and investigation of inter-rater reliability, when used in occupational therapy practice. The instrument was translated from...

  3. Voltammetric determination of norepinephrine in the presence of acetaminophen using a novel ionic liquid/multiwall carbon nanotubes paste electrode

    International Nuclear Information System (INIS)

    Salmanpour, Sadegh; Tavana, Toktam; Pahlavan, Ali; Khalilzadeh, Mohammad A.; Ensafi, Ali A.; Karimi-Maleh, Hassan; Beitollahi, Hadi; Kowsari, Elaheh; Zareyee, Daryoush

    2012-01-01

    A novel multiwall carbon nanotubes (MWCNTs) modified carbon ionic liquid electrode (CILE) was fabricated and used to investigate the electrochemical behavior of norepinephrine (NP). MWCNTs/CILE was prepared by mixing hydrophilic ionic liquid, 1-methyl-3-butylimidazolium bromide (MBIDZBr), with graphite powder, MWCNTs, and liquid paraffin. The fabricated MWCNTs/CILE showed great electrocatalytic ability to the oxidation of NE. The electron transfer coefficient, diffusion coefficient, and charge transfer resistant (R ct ) of NE at the modified electrode were calculated. Differential pulse voltammetry of NE at the modified electrode exhibited two linear dynamic ranges with slopes of 0.0841 and 0.0231 μA/μM in the concentration ranges of 0.3 to 30.0 μM and 30.0 to 450.0 μM, respectively. The detection limit (3σ) of 0.09 μM NP was achieved. This modified electrode exhibited a good ability for well separated oxidation peaks of NE and acetaminophen (AC) in a buffer solution, pH 7.0. The proposed sensor was successfully applied for the determination of NE in human urine, pharmaceutical, and serum samples. Highlights: ► Electrochemical behavior of norepinephrine study using carbon ionic liquid electrode ► This sensor resolved the overlap response of norepinephrine and acetaminophen. ► This sensor is also used for the determination of above compounds in real samples.

  4. Influence of allelic variations in relation to norepinephrine and mineralocorticoid receptors on psychopathic traits: a pilot study

    Directory of Open Access Journals (Sweden)

    Guillaume Durand

    2018-03-01

    Full Text Available Background Past findings support a relationship between abnormalities in the amygdala and the presence of psychopathic traits. Among other genes and biomarkers relevant to the amygdala, norepinephrine and mineralocorticoid receptors might both play a role in psychopathy due to their association with traits peripheral to psychopathy. The purpose is to examine if allelic variations in single nucleotide polymorphisms related to norepinephrine and mineralocorticoid receptors play a role in the display of psychopathic traits and executive functions. Methods Fifty-seven healthy participants from the community provided a saliva sample for SNP sampling of rs5522 and rs5569. Participants then completed the Psychopathic Personality Inventory–Short Form (PPI-SF and the Tower of Hanoi. Results Allelic variations of both rs5522 and rs5569 were significant when compared to PPI-SF total score and the fearless dominance component of the PPI-SF. A significant result was also obtained between rs5522 and the number of moves needed to complete the 5-disk Tower of Hanoi. Conclusion This pilot study offers preliminary results regarding the effect of allelic variations in SNPs related to norepinephrine and mineralocorticoid receptors on the presence of psychopathic traits. Suggestions are provided to enhance the reliability and validity of a larger-scale study.

  5. Clonidine reduces norepinephrine and improves bone marrow function in a rodent model of lung contusion, hemorrhagic shock, and chronic stress.

    Science.gov (United States)

    Alamo, Ines G; Kannan, Kolenkode B; Ramos, Harry; Loftus, Tyler J; Efron, Philip A; Mohr, Alicia M

    2017-03-01

    Propranolol has been shown previously to restore bone marrow function and improve anemia after lung contusion/hemorrhagic shock. We hypothesized that daily clonidine administration would inhibit central sympathetic outflow and restore bone marrow function in our rodent model of lung contusion/hemorrhagic shock with chronic stress. Male Sprague-Dawley rats underwent 6 days of restraint stress after lung contusion/hemorrhagic shock during which the animals received clonidine (75 μg/kg) after the restraint stress. On postinjury day 7, we assessed urine norepinephrine, blood hemoglobin, plasma granulocyte colony stimulating factor, and peripheral blood mobilization of hematopoietic progenitor cells, as well as bone marrow cellularity and erythroid progenitor cell growth. The addition of clonidine to lung contusion/hemorrhagic shock with chronic restraint stress significantly decreased urine norepinephrine levels, improved bone marrow cellularity, restored erythroid progenitor colony growth, and improved hemoglobin (14.1 ± 0.6 vs 10.8 ± 0.6 g/dL). The addition of clonidine to lung contusion/hemorrhagic shock with chronic restraint stress significantly decreased hematopoietic progenitor cells mobilization and restored granulocyte colony stimulating factor levels. After lung contusion/hemorrhagic shock with chronic restraint stress, daily administration of clonidine restored bone marrow function and improved anemia. Alleviating chronic stress and decreasing norepinephrine is a key therapeutic target to improve bone marrow function after severe injury. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. Enabling Wind Power Nationwide

    Energy Technology Data Exchange (ETDEWEB)

    Jose Zayas, Michael Derby, Patrick Gilman and Shreyas Ananthan,

    2015-05-01

    Leveraging this experience, the U.S. Department of Energy’s (DOE’s) Wind and Water Power Technologies Office has evaluated the potential for wind power to generate electricity in all 50 states. This report analyzes and quantifies the geographic expansion that could be enabled by accessing higher above ground heights for wind turbines and considers the means by which this new potential could be responsibly developed.

  7. Relative contributions of norepinephrine and serotonin transporters to antinociceptive synergy between monoamine reuptake inhibitors and morphine in the rat formalin model.

    Directory of Open Access Journals (Sweden)

    Fei Shen

    Full Text Available Multimodal analgesia is designed to optimize pain relief by coadministering drugs with distinct mechanisms of action or by combining multiple pharmacologies within a single molecule. In clinical settings, combinations of monoamine reuptake inhibitors and opioid receptor agonists have been explored and one currently available analgesic, tapentadol, functions as both a µ-opioid receptor agonist and a norepinephrine transporter inhibitor. However, it is unclear whether the combination of selective norepinephrine reuptake inhibition and µ-receptor agonism achieves an optimal antinociceptive synergy. In this study, we assessed the pharmacodynamic interactions between morphine and monoamine reuptake inhibitors that possess different affinities and selectivities for norepinephrine and serotonin transporters. Using the rat formalin model, in conjunction with measurements of ex vivo transporter occupancy, we show that neither the norepinephrine-selective inhibitor, esreboxetine, nor the serotonin-selective reuptake inhibitor, fluoxetine, produce antinociceptive synergy with morphine. Atomoxetine, a monoamine reuptake inhibitor that achieves higher levels of norepinephrine than serotonin transporter occupancy, exhibited robust antinociceptive synergy with morphine. Similarly, a fixed-dose combination of esreboxetine and fluoxetine which achieves comparable levels of transporter occupancy potentiated the antinociceptive response to morphine. By contrast, duloxetine, a monoamine reuptake inhibitor that achieves higher serotonin than norepinephrine transporter occupancy, failed to potentiate the antinociceptive response to morphine. However, when duloxetine was coadministered with the 5-HT3 receptor antagonist, ondansetron, potentiation of the antinociceptive response to morphine was revealed. These results support the notion that inhibition of both serotonin and norepinephrine transporters is required for monoamine reuptake inhibitor and opioid

  8. Synaptic dimorphism in Onychophoran cephalic ganglia

    Directory of Open Access Journals (Sweden)

    Z Peña-Contreras

    2007-03-01

    Full Text Available The taxonomic location of the Onychophora has been controversial because of their phenotypic and genotypic characteristics, related to both annelids and arthropods. We analyzed the ultrastructure of the neurons and their synapses in the cephalic ganglion of a poorly known invertebrate, the velvet worm Peripatus sedgwicki, from the mountainous region of El Valle, Mérida, Venezuela. Cephalic ganglia were dissected, fixed and processed for transmission electron microscopy. The animal has a high degree of neurobiological development, as evidenced by the presence of asymmetric (excitatory and symmetric (inhibitory synapses, as well as the existence of glial cell processes in a wide neuropile zone. The postsynaptic terminals were seen to contain subsynaptic cisterns formed by membranes of smooth endoplasmic reticulum beneath the postsynaptic density, whereas the presynaptic terminal showed numerous electron transparent synaptic vesicles. From the neurophylogenetic perspectives, the ultrastructural characteristics of the central nervous tissue of the Onychophora show important evolutionary acquirements, such as the presence of both excitatory and inhibitory synapses, indicating functional synaptic transmission, and the appearance of mature glial cells. Rev. Biol . Trop. 55 (1: 261-267. Epub 2007 March. 31.Estudiamos la ultraestructura de las neuronas y sus sinapsis del ganglio cefálico de un invertebrado poco conocido del phylum Onychophora: Peripatus sedgwicki de los Andes Venezolanos, utilizando para ello la microscopía electrónica de transmisión. La localización taxonómica de los onicóforos ha sido controversial debido a sus características fenotípicas y genotípicas que los relacionan tanto con los anélidos como con los artrópodos. Para este trabajo se estudió el ganglio cefálico de P. sedgwicki de la zona montañosa de El Valle, Mérida, Venezuela. El ganglio cefálico se localiza en la región anterior del animal y fue diseccionado

  9. Identification of synaptic targets of Drosophila pumilio.

    Directory of Open Access Journals (Sweden)

    Gengxin Chen

    2008-02-01

    Full Text Available Drosophila Pumilio (Pum protein is a translational regulator involved in embryonic patterning and germline development. Recent findings demonstrate that Pum also plays an important role in the nervous system, both at the neuromuscular junction (NMJ and in long-term memory formation. In neurons, Pum appears to play a role in homeostatic control of excitability via down regulation of para, a voltage gated sodium channel, and may more generally modulate local protein synthesis in neurons via translational repression of eIF-4E. Aside from these, the biologically relevant targets of Pum in the nervous system remain largely unknown. We hypothesized that Pum might play a role in regulating the local translation underlying synapse-specific modifications during memory formation. To identify relevant translational targets, we used an informatics approach to predict Pum targets among mRNAs whose products have synaptic localization. We then used both in vitro binding and two in vivo assays to functionally confirm the fidelity of this informatics screening method. We find that Pum strongly and specifically binds to RNA sequences in the 3'UTR of four of the predicted target genes, demonstrating the validity of our method. We then demonstrate that one of these predicted target sequences, in the 3'UTR of discs large (dlg1, the Drosophila PSD95 ortholog, can functionally substitute for a canonical NRE (Nanos response element in vivo in a heterologous functional assay. Finally, we show that the endogenous dlg1 mRNA can be regulated by Pumilio in a neuronal context, the adult mushroom bodies (MB, which is an anatomical site of memory storage.

  10. EnableATIS strategy assessment.

    Science.gov (United States)

    2014-02-01

    Enabling Advanced Traveler Information Systems (EnableATIS) is the traveler information component of the Dynamic Mobility Application (DMA) program. The objective of : the EnableATIS effort is to foster transformative traveler information application...

  11. Enabling Digital Literacy

    DEFF Research Database (Denmark)

    Ryberg, Thomas; Georgsen, Marianne

    2010-01-01

    There are some tensions between high-level policy definitions of “digital literacy” and actual teaching practice. We need to find workable definitions of digital literacy; obtain a better understanding of what digital literacy might look like in practice; and identify pedagogical approaches, which...... support teachers in designing digital literacy learning. We suggest that frameworks such as Problem Based Learning (PBL) are approaches that enable digital literacy learning because they provide good settings for engaging with digital literacy. We illustrate this through analysis of a case. Furthermore......, these operate on a meso-level mediating between high-level concepts of digital literacy and classroom practice....

  12. CtOS Enabler

    OpenAIRE

    Crespo Cepeda, Rodrigo; El Yamri El Khatibi, Meriem; Carrera García, Juan Manuel

    2015-01-01

    Las Smart Cities son, indudablemente, el futuro próximo de la tecnología al que nos acercamos cada día, lo que se puede observar en la abundancia de dispositivos móviles entre la población, que informatizan la vida cotidiana mediante el uso de la geolocalización y la información. Pretendemos unir estos dos ámbitos con CtOS Enabler para crear un estándar de uso que englobe todos los sistemas de Smart Cities y facilite a los desarrolladores de dicho software la creación de nuevas herramientas. ...

  13. Synaptic vesicle dynamic changes in a model of fragile X.

    Science.gov (United States)

    Broek, Jantine A C; Lin, Zhanmin; de Gruiter, H Martijn; van 't Spijker, Heleen; Haasdijk, Elize D; Cox, David; Ozcan, Sureyya; van Cappellen, Gert W A; Houtsmuller, Adriaan B; Willemsen, Rob; de Zeeuw, Chris I; Bahn, Sabine

    2016-01-01

    Fragile X syndrome (FXS) is a single-gene disorder that is the most common heritable cause of intellectual disability and the most frequent monogenic cause of autism spectrum disorders (ASD). FXS is caused by an expansion of trinucleotide repeats in the promoter region of the fragile X mental retardation gene (Fmr1). This leads to a lack of fragile X mental retardation protein (FMRP), which regulates translation of a wide range of messenger RNAs (mRNAs). The extent of expression level alterations of synaptic proteins affected by FMRP loss and their consequences on synaptic dynamics in FXS has not been fully investigated. Here, we used an Fmr1 knockout (KO) mouse model to investigate the molecular mechanisms underlying FXS by monitoring protein expression changes using shotgun label-free liquid-chromatography mass spectrometry (LC-MS(E)) in brain tissue and synaptosome fractions. FXS-associated candidate proteins were validated using selected reaction monitoring (SRM) in synaptosome fractions for targeted protein quantification. Furthermore, functional alterations in synaptic release and dynamics were evaluated using live-cell imaging, and interpretation of synaptic dynamics differences was investigated using electron microscopy. Key findings relate to altered levels of proteins involved in GABA-signalling, especially in the cerebellum. Further exploration using microscopy studies found reduced synaptic vesicle unloading of hippocampal neurons and increased vesicle unloading in cerebellar neurons, which suggests a general decrease of synaptic transmission. Our findings suggest that FMRP is a regulator of synaptic vesicle dynamics, which supports the role of FMRP in presynaptic functions. Taken together, these studies provide novel insights into the molecular changes associated with FXS.

  14. Modulation of extrasynaptic NMDA receptors by synaptic and tonic zinc.

    Science.gov (United States)

    Anderson, Charles T; Radford, Robert J; Zastrow, Melissa L; Zhang, Daniel Y; Apfel, Ulf-Peter; Lippard, Stephen J; Tzounopoulos, Thanos

    2015-05-19

    Many excitatory synapses contain high levels of mobile zinc within glutamatergic vesicles. Although synaptic zinc and glutamate are coreleased, it is controversial whether zinc diffuses away from the release site or whether it remains bound to presynaptic membranes or proteins after its release. To study zinc transmission and quantify zinc levels, we required a high-affinity rapid zinc chelator as well as an extracellular ratiometric fluorescent zinc sensor. We demonstrate that tricine, considered a preferred chelator for studying the role of synaptic zinc, is unable to efficiently prevent zinc from binding low-nanomolar zinc-binding sites, such as the high-affinity zinc-binding site found in NMDA receptors (NMDARs). Here, we used ZX1, which has a 1 nM zinc dissociation constant and second-order rate constant for binding zinc that is 200-fold higher than those for tricine and CaEDTA. We find that synaptic zinc is phasically released during action potentials. In response to short trains of presynaptic stimulation, synaptic zinc diffuses beyond the synaptic cleft where it inhibits extrasynaptic NMDARs. During higher rates of presynaptic stimulation, released glutamate activates additional extrasynaptic NMDARs that are not reached by synaptically released zinc, but which are inhibited by ambient, tonic levels of nonsynaptic zinc. By performing a ratiometric evaluation of extracellular zinc levels in the dorsal cochlear nucleus, we determined the tonic zinc levels to be low nanomolar. These results demonstrate a physiological role for endogenous synaptic as well as tonic zinc in inhibiting extrasynaptic NMDARs and thereby fine tuning neuronal excitability and signaling.

  15. Modulation of extrasynaptic NMDA receptors by synaptic and tonic zinc

    Science.gov (United States)

    Anderson, Charles T.; Radford, Robert J.; Zastrow, Melissa L.; Zhang, Daniel Y.; Apfel, Ulf-Peter; Lippard, Stephen J.; Tzounopoulos, Thanos

    2015-01-01

    Many excitatory synapses contain high levels of mobile zinc within glutamatergic vesicles. Although synaptic zinc and glutamate are coreleased, it is controversial whether zinc diffuses away from the release site or whether it remains bound to presynaptic membranes or proteins after its release. To study zinc transmission and quantify zinc levels, we required a high-affinity rapid zinc chelator as well as an extracellular ratiometric fluorescent zinc sensor. We demonstrate that tricine, considered a preferred chelator for studying the role of synaptic zinc, is unable to efficiently prevent zinc from binding low-nanomolar zinc-binding sites, such as the high-affinity zinc-binding site found in NMDA receptors (NMDARs). Here, we used ZX1, which has a 1 nM zinc dissociation constant and second-order rate constant for binding zinc that is 200-fold higher than those for tricine and CaEDTA. We find that synaptic zinc is phasically released during action potentials. In response to short trains of presynaptic stimulation, synaptic zinc diffuses beyond the synaptic cleft where it inhibits extrasynaptic NMDARs. During higher rates of presynaptic stimulation, released glutamate activates additional extrasynaptic NMDARs that are not reached by synaptically released zinc, but which are inhibited by ambient, tonic levels of nonsynaptic zinc. By performing a ratiometric evaluation of extracellular zinc levels in the dorsal cochlear nucleus, we determined the tonic zinc levels to be low nanomolar. These results demonstrate a physiological role for endogenous synaptic as well as tonic zinc in inhibiting extrasynaptic NMDARs and thereby fine tuning neuronal excitability and signaling. PMID:25947151

  16. Modeling and analysis of PET studies with norepinephrine transporter ligands: the search for a reference region

    Energy Technology Data Exchange (ETDEWEB)

    Logan, Jean [Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973 (United States)]. E-mail: logan@bnl.gov; Ding, Y.-S. [Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973 (United States); Lin, K.-S. [Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973 (United States); Pareto, Deborah [Medical Department, Brookhaven National Laboratory, Upton, NY 11973 (United States); Functional Imaging, Berkeley National Laboratory, Berkeley, CA 94720 (United States); Fowler, Joanna [Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973 (United States); Biegon, Anat [Medical Department, Brookhaven National Laboratory, Upton, NY 11973 (United States)

    2005-07-01

    The development of positron emission tomography (PET) ligands for the norepinephrine transporter (NET) has been slow compared to the development of radiotracers for others systems, such as the dopamine (DAT) or the serotonin transporters (SERT). The main reason for this appears to be the high nonspecific (non-NET) binding exhibited by many of these tracers, which makes the identification of a reference region difficult. With other PET ligands the use of a reference region increases the reproducibility of the outcome measure in test/retest studies. The focus of this work is to identify a suitable reference region or means of normalizing data for the NET ligands investigated. Methods: We have analyzed the results of PET studies in the baboon brain with labeled reboxetine derivatives (S,S)-[{sup 11}C]O-methyl reboxetine (SS-MRB), (S,S)-[{sup 18}F]fluororeboxetine (SS-FRB) as well as O-[{sup 11}C]nisoxetine and N-[{sup 11}C]nisoxetine (NIS), and, for comparison, the less active (R,R) enantiomers (RR-MRB, RR-FRB) in terms of the distribution volume (DV) using measured arterial input functions. Results: (1) For a given subject, a large variation in DV for successive baseline studies was observed in regions with both high and low NET density. (2) The occipital cortex and the basal ganglia were found to be the regions with the smallest change between baseline (SS-MRB) and pretreatment with cocaine, and were therefore used as a composite reference region for calculation of a distribution volume ratio (DVR). (3) The variability [as measured by the coefficient of variation (CV)=standard deviation/mean] in the distribution volume ratio (DVR) of thalamus (to reference region) was considerably reduced over that of the DV using this composite reference region. (4) Pretreatment with nisoxetine (1.0 mg/kg 10 min prior to tracer) in one study produced (in decreasing order) reductions in thalamus, cerebellum, cingulate and frontal cortex consistent with known NET densities. (5) [{sup

  17. Modeling and analysis of PET studies with norepinephrine transporter ligands: the search for a reference region.

    Science.gov (United States)

    Logan, Jean; Ding, Yu-Shin; Lin, Kuo-Shyan; Pareto, Deborah; Fowler, Joanna; Biegon, Anat

    2005-07-01

    The development of positron emission tomography (PET) ligands for the norepinephrine transporter (NET) has been slow compared to the development of radiotracers for others systems, such as the dopamine (DAT) or the serotonin transporters (SERT). The main reason for this appears to be the high nonspecific (non-NET) binding exhibited by many of these tracers, which makes the identification of a reference region difficult. With other PET ligands the use of a reference region increases the reproducibility of the outcome measure in test/retest studies. The focus of this work is to identify a suitable reference region or means of normalizing data for the NET ligands investigated. We have analyzed the results of PET studies in the baboon brain with labeled reboxetine derivatives (S,S)-[(11)C]O-methyl reboxetine (SS-MRB), (S,S)-[(18)F]fluororeboxetine (SS-FRB) as well as O-[(11)C]nisoxetine and N-[(11)C]nisoxetine (NIS), and, for comparison, the less active (R,R) enantiomers (RR-MRB, RR-FRB) in terms of the distribution volume (DV) using measured arterial input functions. (1) For a given subject, a large variation in DV for successive baseline studies was observed in regions with both high and low NET density. (2) The occipital cortex and the basal ganglia were found to be the regions with the smallest change between baseline (SS-MRB) and pretreatment with cocaine, and were therefore used as a composite reference region for calculation of a distribution volume ratio (DVR). (3) The variability [as measured by the coefficient of variation (CV) = standard deviation/mean] in the distribution volume ratio (DVR) of thalamus (to reference region) was considerably reduced over that of the DV using this composite reference region. (4) Pretreatment with nisoxetine (1.0 mg/kg 10 min prior to tracer) in one study produced (in decreasing order) reductions in thalamus, cerebellum, cingulate and frontal cortex consistent with known NET densities. (5) [(11)C]Nisoxetine had a higher

  18. Modeling and analysis of PET studies with norepinephrine transporter ligands: the search for a reference region

    International Nuclear Information System (INIS)

    Logan, Jean; Ding, Y.-S.; Lin, K.-S.; Pareto, Deborah; Fowler, Joanna; Biegon, Anat

    2005-01-01

    The development of positron emission tomography (PET) ligands for the norepinephrine transporter (NET) has been slow compared to the development of radiotracers for others systems, such as the dopamine (DAT) or the serotonin transporters (SERT). The main reason for this appears to be the high nonspecific (non-NET) binding exhibited by many of these tracers, which makes the identification of a reference region difficult. With other PET ligands the use of a reference region increases the reproducibility of the outcome measure in test/retest studies. The focus of this work is to identify a suitable reference region or means of normalizing data for the NET ligands investigated. Methods: We have analyzed the results of PET studies in the baboon brain with labeled reboxetine derivatives (S,S)-[ 11 C]O-methyl reboxetine (SS-MRB), (S,S)-[ 18 F]fluororeboxetine (SS-FRB) as well as O-[ 11 C]nisoxetine and N-[ 11 C]nisoxetine (NIS), and, for comparison, the less active (R,R) enantiomers (RR-MRB, RR-FRB) in terms of the distribution volume (DV) using measured arterial input functions. Results: (1) For a given subject, a large variation in DV for successive baseline studies was observed in regions with both high and low NET density. (2) The occipital cortex and the basal ganglia were found to be the regions with the smallest change between baseline (SS-MRB) and pretreatment with cocaine, and were therefore used as a composite reference region for calculation of a distribution volume ratio (DVR). (3) The variability [as measured by the coefficient of variation (CV)=standard deviation/mean] in the distribution volume ratio (DVR) of thalamus (to reference region) was considerably reduced over that of the DV using this composite reference region. (4) Pretreatment with nisoxetine (1.0 mg/kg 10 min prior to tracer) in one study produced (in decreasing order) reductions in thalamus, cerebellum, cingulate and frontal cortex consistent with known NET densities. (5) [ 11 C]Nisoxetine had

  19. Smart Grid Enabled EVSE

    Energy Technology Data Exchange (ETDEWEB)

    None, None

    2015-01-12

    The combined team of GE Global Research, Federal Express, National Renewable Energy Laboratory, and Consolidated Edison has successfully achieved the established goals contained within the Department of Energy’s Smart Grid Capable Electric Vehicle Supply Equipment funding opportunity. The final program product, shown charging two vehicles in Figure 1, reduces by nearly 50% the total installed system cost of the electric vehicle supply equipment (EVSE) as well as enabling a host of new Smart Grid enabled features. These include bi-directional communications, load control, utility message exchange and transaction management information. Using the new charging system, Utilities or energy service providers will now be able to monitor transportation related electrical loads on their distribution networks, send load control commands or preferences to individual systems, and then see measured responses. Installation owners will be able to authorize usage of the stations, monitor operations, and optimally control their electricity consumption. These features and cost reductions have been developed through a total system design solution.

  20. Association of Posttraumatic Stress Disorder With Reduced In Vivo Norepinephrine Availability in the Locus Coeruleus

    Science.gov (United States)

    Pietrzak, Robert H.; Gallezot, Jean-Dominique; Ding, Yu-Shin; Henry, Shannan; Potenza, Marc N.; Southwick, Steven M.; Krystal, John H.; Carson, Richard E.; Neumeister, Alexander

    2014-01-01

    IMPORTANCE Animal data suggest that chronic stress is associated with a reduction in norepinephrine transporter (NET) availability in the locus coeruleus. However, it is unclear whether such models are relevant to posttraumatic stress disorder (PTSD), which has been linked to noradrenergic dysfunction in humans. OBJECTIVES To use positron emission tomography and the radioligand [11C]methylreboxetine to examine in vivo NET availability in the locus coeruleus in the following 3 groups of individuals: healthy adults (HC group), adults exposed to trauma who did not develop PTSD (TC group), and adults exposed to trauma who developed PTSD (PTSD group) and to evaluate the relationship between NET availability in the locus coeruleus and a contemporary phenotypic model of PTSD symptoms. DESIGN, SETTING, AND PARTICIPANTS Cross-sectional positron emission tomography study under resting conditions at academic and Veterans Affairs medical centers among 56 individuals in the following 3 study groups: HC (n = 18), TC (n = 16), and PTSD (n = 22). MAIN OUTCOMES AND MEASURES The [11C]methylreboxetine-binding potential of NET availability in the locus coeruleus and the severity of PTSD symptoms assessed using the Clinician-Administered PTSD Scale. RESULTS The PTSD group had significantly lower NET availability than the HC group (41% lower, Cohen d = 1.07). NET availability did not differ significantly between the TC and HC groups (31% difference, Cohen d = 0.79) or between the TC and PTSD groups (15% difference, Cohen d = 0.28). In the PTSD group, NET availability in the locus coeruleus was independently positively associated with the severity of anxious arousal (ie, hypervigilance) symptoms (r = 0.52) but not with any of the other PTSD symptom clusters. CONCLUSIONS AND RELEVANCE These results suggest that PTSD is associated with significantly reduced NET availability in the locus coeruleus and that greater NET availability in this brain region is associated with increased severity

  1. Optogenetic release of norepinephrine from cardiac sympathetic neurons alters mechanical and electrical function.

    Science.gov (United States)

    Wengrowski, Anastasia M; Wang, Xin; Tapa, Srinivas; Posnack, Nikki Gillum; Mendelowitz, David; Kay, Matthew W

    2015-02-01

    Release of norepinephrine (NE) from sympathetic neurons enhances heart rate (HR) and developed force through activation of β-adrenergic receptors, and this sympathoexcitation is a key risk for the generation of cardiac arrhythmias. Studies of β-adrenergic modulation of cardiac function typically involve the administration of exogenous β-adrenergic receptor agonists to directly elicit global β-adrenergic receptor activation by bypassing the involvement of sympathetic nerve terminals. In this work, we use a novel method to activate sympathetic fibres within the myocardium of Langendorff-perfused hearts while measuring changes in electrical and mechanical function. The light-activated optogenetic protein channelrhodopsin-2 (ChR2) was expressed in murine catecholaminergic sympathetic neurons. Sympathetic fibres were then photoactivated to examine changes in contractile force, HR, and cardiac electrical activity. Incidence of arrhythmia was measured with and without exposure to photoactivation of sympathetic fibres, and hearts were optically mapped to detect changes in action potential durations and conduction velocities. Results demonstrate facilitation of both developed force and HR after photostimulated release of NE, with increases in contractile force and HR of 34.5 ± 5.5 and 25.0 ± 9.3%, respectively. Photostimulation of sympathetic fibres also made hearts more susceptible to arrhythmia, with greater incidence and severity. In addition, optically mapped action potentials displayed a small but significant shortening of the plateau phase (-5.5 ± 1.0 ms) after photostimulation. This study characterizes a powerful and clinically relevant new model for studies of cardiac arrhythmias generated by increasing the activity of sympathetic nerve terminals and the resulting activation of myocyte β-adrenergic receptors. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email: journals.permissions@oup.com.

  2. Reserpine-induced reduction in norepinephrine transporter function requires catecholamine storage vesicles.

    Science.gov (United States)

    Mandela, Prashant; Chandley, Michelle; Xu, Yao-Yu; Zhu, Meng-Yang; Ordway, Gregory A

    2010-01-01

    Treatment of rats with reserpine, an inhibitor of the vesicular monoamine transporter (VMAT), depletes norepinephrine (NE) and regulates NE transporter (NET) expression. The present study examined the molecular mechanisms involved in regulation of the NET by reserpine using cultured cells. Exposure of rat PC12 cells to reserpine for a period as short as 5min decreased [(3)H]NE uptake capacity, an effect characterized by a robust decrease in the V(max) of the transport of [(3)H]NE. As expected, reserpine did not displace the binding of [(3)H]nisoxetine from the NET in membrane homogenates. The potency of reserpine for reducing [(3)H]NE uptake was dramatically lower in SK-N-SH cells that have reduced storage capacity for catecholamines. Reserpine had no effect on [(3)H]NE uptake in HEK-293 cells transfected with the rat NET (293-hNET), cells that lack catecholamine storage vesicles. NET regulation by reserpine was independent of trafficking of the NET from the cell surface. Pre-exposure of cells to inhibitors of several intracellular signaling cascades known to regulate the NET, including Ca(2+)/Ca(2+)-calmodulin dependent kinase and protein kinases A, C and G, did not affect the ability of reserpine to reduce [(3)H]NE uptake. Treatment of PC12 cells with the catecholamine depleting agent, alpha-methyl-p-tyrosine, increased [(3)H]NE uptake and eliminated the inhibitory effects of reserpine on [(3)H]NE uptake. Reserpine non-competitively inhibits NET activity through a Ca(2+)-independent process that requires catecholamine storage vesicles, revealing a novel pharmacological method to modify NET function. Further characterization of the molecular nature of reserpine's action could lead to the development of alternative therapeutic strategies for treating disorders known to be benefitted by treatment with traditional competitive NET inhibitors. Copyright 2010 Elsevier Ltd. All rights reserved.

  3. Effects of cocaine on norepinephrine stimulated phosphoinositide hydrolysis and locomotor activity in rat

    International Nuclear Information System (INIS)

    Mosaddeghi, M.

    1989-01-01

    The function of α 1 -adrenoceptors was determined by stimulating cortical tissue slices, which were pre-labeled with [ 3 H]inositol, with norepinephrine (NE) in the presence of 8 mM LiCl. Results of in vitro studies showed that cocaine 10 μM potentiated maximal NE-stimulated PI hydrolysis by 30%. In addition, the EC 50 was decreased from 3.93 ± 0.42 to 1.91 ± 0.31 μM NE. Concentrations of 0.1-100 μM and 0.1-10 μM cocaine enhanced PI hydrolysis stimulated by 0.3 and 3 μM NE, respectively. The concentration-effect curves for NE-stimulated PI hydrolysis were shifted to the right 100-fold in the presence of 0.1 μM prazosin. Cocaine (10 μM) did not potentiate NE-stimulated PI hydrolysis in the presence of 0.1 μM prazosin. [ 3 H]Prazosin saturation and NE [ 3 H]prazosin competition binding studies using crude membrane preparations showed that 10 μM cocaine did not alter binding parameters B max , K d , Hill slope, and IC 50 . Together, these results implied that cocaine in vitro potentiated NE-stimulated PI hydrolysis by blocking NE reuptake. For in vivo studies, the locomotor activity was determined after an acute or chronic injections of either cocaine or saline. Cocaine or saline-treated rats were killed after measurement of the locomotor activity, and NE-stimulated PI hydrolysis was measured. Acute administration of cocaine 3.2-42 mg/kg (i.p.) produced an inverted U shaped dose-response curve on locomotor activity. The peak increase in locomotor activity was at 32 mg/kg cocaine. A dose of 42 mg/kg cocaine produced a significant depression of maximal NE-stimulated PI hydrolysis

  4. Norepinephrine inhibition of mesenchymal stem cell and chondrogenic progenitor cell chondrogenesis and acceleration of chondrogenic hypertrophy.

    Science.gov (United States)

    Jenei-Lanzl, Zsuzsa; Grässel, Susanne; Pongratz, Georg; Kees, Frieder; Miosge, Nicolai; Angele, Peter; Straub, Rainer H

    2014-09-01

    Mesenchymal progenitor cell chondrogenesis is the biologic platform for the generation or regeneration of cartilage, but the external influence of the sympathetic nervous system on this process is not yet known. Sympathetic nerve fibers are present in articular tissue, and the sympathetic nervous system influences the musculoskeletal system by, for example, increasing osteoclastogenesis. This study was initiated to explore the role of the sympathetic neurotransmitter norepinephrine (NE) in mesenchymal stem cell (MSC)-dependent and cartilage progenitor cell (CPC)-dependent chondrogenesis. Using human MSCs or CPCs, chondrogenic differentiation was induced in the presence of NE, the specific β-adrenergic receptor (β-AR) agonist isoproterenol, and the specific β-AR antagonist nadolol. We studied sympathetic nerve fibers, tyrosine hydroxylase (TH) expression, catecholamine biosynthesis, and synovial fluid levels in human joints, as well as cartilage-specific matrix deposition during differentiation. TH+ sympathetic nerve fibers were present in the synovial tissue, meniscus, and subchondral bone marrow. In addition, synovial fluid from patients with knee trauma demonstrated high concentrations of NE. During MSC or CPC chondrogenesis, β-AR were expressed. Chondrogenic aggregates treated with NE or isoproterenol synthesized lower amounts of type II collagen and glycosaminoglycans. NE and isoproterenol treatment dose-dependently increased the levels of cartilage hypertrophy markers (type X collagen and matrix metalloproteinase 13). Nadolol reversed the inhibition of chondrogenesis and the up-regulation of cartilage hypertrophy. Our findings demonstrate NE-dependent inhibition of chondrogenesis and acceleration of hypertrophic differentiation. By inhibiting cartilage repair, these sympathetic influences can be important after joint trauma. These findings may be a basis for novel neurochondrogenic therapeutic options. Copyright © 2014 by the American College of

  5. Immunomodulation Mechanism of Antidepressants: Interactions between Serotonin/Norepinephrine Balance and Th1/Th2 Balance

    Science.gov (United States)

    Martino, Matteo; Rocchi, Giulio; Escelsior, Andrea; Fornaro, Michele

    2012-01-01

    Neurotransmitters and hormones regulate major immune functions, including the selection of T helper (Th)1 or Th2 cytokine responses, related to cell-mediated and humoral immunity, respectively. A role of imbalance and dynamic switching of Th1/Th2 system has been proposed, with relative displacement of the immune reserve in relation to complex interaction between Th1/Th2 and neuro-hormonal balance fluctuations, in the pathogenesis of various chronic human diseases, probably also including psychiatric disorders. Components of the stress system such as norepinephrine (NE) and glucocorticoids appear to mediate a Th2 shift, while serotonin (5-HT) and melatonin might mediate a Th1 shift. Some antidepressants would occur affecting these systems, acting on neurotransmitter balance (especially the 5-HT/NE balance) and expression levels of receptor subtypes, which in turn affect cytokine production and relative Th1/Th2 balance. It could be therefore hypothesized that the antidepressant-related increase in NE tone enhances the Th2 response, while the decrease in NE tone or the increase in 5-HT tone enhances the Th1 response. However, the neurotransmitter and Th1/Th2 balance modulation could be relative, aiming to restore physiological levels a previous imbalance in receptor sensitivity and cytokine production. The considerations on neuro-immunomodulation could represent an additional aid in the study of pathophysiology of psychiatric disorders and in the choice of specific antidepressants in specific clusters of symptoms, especially in comorbidity with internal pathologies. Furthermore limited data, reviewed here, have shown the effectiveness of some antidepressants as pure immunomodulators. However, these considerations are tentative and require experimental confirmation or refutation by future studies. PMID:23204981

  6. Selective binding of 2-[125I]iodo-nisoxetine to norepinephrine transporters in the brain

    International Nuclear Information System (INIS)

    Kung, M.-P.; Choi, Seok-Rye; Hou, Catherine; Zhuang, Z.-P.; Foulon, Catherine; Kung, Hank F.

    2004-01-01

    A radioiodinated ligand, (R)-N-methyl-(2-[ 125 I]iodo-phenoxy)-3-phenylpropylamine, [ 125 I]2-INXT, targeting norepinephrine transporters (NET), was successfully prepared. A no-carrier-added product, [ 125 I]2-INXT, displayed a saturable binding with a high affinity (K d =0.06 nM) in the homogenates prepared from rat cortical tissues as well as from LLC-PK 1 cells expressing NET. A relatively low number of binding sties (B max =55 fmol/mg protein) measured with [ 125 I]2-INXT in rat cortical homogenates is consistent with the value reported for a known NET ligand, [ 3 H]nisoxetine. Competition studies with various compounds on [ 125 I]2-INXT binding clearly confirmed the pharmacological specificity and selectivity for NET binding sites. Following a tail-vein injection of [ 125 I]2-INXT in rats, a good initial brain uptake was observed (0.56% dose at 2 min) followed by a slow washout from the brain (0.2% remained at 3 hours post-injection). The hypothalamus (a NET-rich region) to striatum (a region devoid of NET) ratio was 1.5 at 3 hours post-i.v. injection. Pretreatment of rats with nisoxetine significantly inhibited the uptake of [ 125 I]2-INXT (70-100% inhibition) in locus coeruleus, hypothalamus and raphe nuclei, regions known to have a high density of NET; whereas escitalopram, a serotonin transporter ligand, did not show a similar effect. Ex vivo autoradiography of rat brain sections of [ 125 I]2-INXT (at 3 hours after an i.v. injection) displayed an excellent regional brain localization pattern corroborated to the specific NET distribution in the brain. The specific brain localization was significantly reduced by a dose of nisoxetine pretreatment. Taken together, the data suggest that [ 123 I]2-INXT may be useful for mapping NET binding sites in the brain

  7. Evidence that two stereochemically different alpha-2 adrenoceptors modulate norepinephrine release in rat cerebral cortex

    Energy Technology Data Exchange (ETDEWEB)

    Harsing, L.G. Jr.; Vizi, E.S. (Institute of Experimental Medicine, Budapest (Hungary))

    1991-01-01

    Cerebral cortex slices from the rat were loaded with (3H)norepinephrine ((3H)NE) and superfused in order to measure the release of radioactivity at rest and in response to electrical stimulation. The (-)-isomer and the (+)-isomer of CH-38083 (7,8-(methylenedioxy)-14- alpha-hydroxyalloberbane HCl), a selective alpha-2-adrenoceptor antagonist with an alloberbane skeleton, increased the electrically induced release of (3H)NE in a concentration-dependent manner, and a similar effect was observed with racemic CH-38083 and idazoxan. The stereoisomers of CH-38083 applied in a concentration range of 10(-8) to 10(-6) mol/l were equipotent in facilitating stimulation-evoked (3H)NE release: concentrations needed to enhance tritium outflow by 50% were 1.3 X 10(-7) mol/l for (-)-CH-38083 and 1.4 X 10(-7) mol/l for (+)-CH-38083. Exogenous NE decreased the electrically stimulated release of (3H)NE, and the stereoisomers of CH-38083 antagonized this inhibition with different potencies: the dissociation constant (KB) values for (-)-isomer and for (+)-isomer of CH-38083 were 14.29 and 97.18 nmol/l. These data indicate that presynaptic alpha-2 adrenoceptors that are available for NE released from axon terminals do not show stereospecificity toward enantiomers of CH-38083, whereas those that are occupied by exogenous NE are much more sensitive toward (-)-CH-38083. The alpha-1 adrenoceptor antagonist prazosin also differentiated between the alpha-2 adrenoceptor subtypes: prazosin (10(-6) mol/l) did not alter the increase of electrically induced (3H)NE release evoked by (-)- and (+)-CH-38083; however, in its presence, the stereoisomers of CH-38083 failed to antagonize the inhibitory effect of exogenous NE on its own release.

  8. Napping reverses the salivary interleukin-6 and urinary norepinephrine changes induced by sleep restriction.

    Science.gov (United States)

    Faraut, Brice; Nakib, Samir; Drogou, Catherine; Elbaz, Maxime; Sauvet, Fabien; De Bandt, Jean-Pascal; Léger, Damien

    2015-03-01

    Neuroendocrine and immune stresses imposed by chronic sleep restriction are known to be involved in the harmful cardiovascular effects associated with poor sleep. Despite a well-known beneficial effect of napping on alertness, its effects on neuroendocrine stress and immune responses after sleep restriction are largely unknown. This study was a strictly controlled (sleep-wake status, light environment, caloric intake), crossover, randomized design in continuously polysomnography-monitored subjects. The study was conducted in a laboratory-based study. The subjects were 11 healthy young men. We investigated the effects on neuroendocrine and immune biomarkers of a night of sleep restricted to 2 h followed by a day without naps or with 30 minute morning and afternoon naps, both conditions followed by an ad libitum recovery night starting at 20:00. Salivary interleukin-6 and urinary catecholamines were assessed throughout the daytime study periods. The increase in norepinephrine values seen at the end of the afternoon after the sleep-restricted night was not present when the subjects had the opportunity to take naps. Interleukin-6 changes observed after sleep deprivation were also normalized after napping. During the recovery day in the no-nap condition, there were increased levels of afternoon epinephrine and dopamine, which was not the case in the nap condition. A recovery night after napping was associated with a reduced amount of slow-wave sleep compared to after the no-nap condition. Our data suggest that napping has stress-releasing and immune effects. Napping could be easily applied in real settings as a countermeasure to the detrimental health consequences of sleep debt.

  9. Neurotensin releases norepinephrine differentially from perfused hypothalamus of sated and fasted rat

    International Nuclear Information System (INIS)

    Lee, T.F.; Rezvani, A.H.; Hepler, J.R.; Myers, R.D.

    1987-01-01

    The central injection of neurotensin (NT) has been reported to attenuate the intake of food in the fasted animal. To determine whether endogenous norepinephrine (NE) is involved in the satiating effect of NT, the in vivo activity of NE in circumscribed sites in the hypothalamus of the unanesthetized rat was examined. Bilateral guide tubes for push-pull perfusion were implanted stereotaxically to rest permanently above one of several intended sites of perfusion, which included the paraventricular nucleus (PVN), ventromedial nucleus (VMN), and the lateral hypothalamic (LH) area. After endogenous stores of NE at a specific hypothalamic locus were radiolabeled by microinjection of 0.02-0.5 μCi of [ 3 H]NE, an artificial cerebrospinal fluid was perfused at the site at a rate of 20 μl/min over successive intervals of 5.0 min. When 0.05 or 0.1 μg/μl NT was added to the perfusate, the peptide served either to enhance or educe the local release of NE at 50% of the sites of perfusion. In these experiments, the circumscribed effect of NT on the characteristics of catecholamine efflux depended entirely on the state of hunger or satiety of the rat. That is, when NT was perfused in the fully satiated rat, NE release was augmented within the PVn or VMN; conversely, NE release was inhibited in the LH. in the animal fasted for 18-22 h, NT exerted an opposite effect on the activity of NE within the same anatomical loci in that the efflux of NE was enhanced in the LH but attenuated or unaffected in the PVN or VMN. Taken together, these observations provide experimental support for the view-point that NT could act as a neuromodulator of the activity of hypothalamic noradrenergic neurons that are thought to play a functional role in the regulation of food intake

  10. Hunger and disinhibition but not cognitive restraint are associated with central norepinephrine transporter availability.

    Science.gov (United States)

    Bresch, A; Rullmann, M; Luthardt, J; Becker, G A; Patt, M; Ding, Y-S; Hilbert, A; Sabri, O; Hesse, S

    2017-10-01

    The relationship between food-intake related behaviours measured by the Three-Factor Eating Questionnaire (TFEQ) and in vivo norepinephrine transporter (NET) availability has not been explored yet. We investigated ten obese individuals (body mass index (BMI) 42.4 ± 3.7 kg/m 2 ) and ten normal-weight healthy controls (HC, BMI 23.9 ± 2.5 kg/m 2 ) with (S,S)-[ 11 C]-O-methylreboxetine ([ 11 C]MRB) positron emission tomography (PET). All participants completed the TFEQ, which measures cognitive restraint, disinhibition and hunger. Image analysis required magnetic resonance imaging data sets onto which volumes-of-interests were drawn. Tissue time activity curves (TACs) were obtained from the dynamic PET data followed by kinetic modeling of these regional brain TACs applying the multilinear reference tissue model (2 parameters) with the occipital cortex as reference region. Obese individuals scored significantly higher on the hunger subscale of the TFEQ. Correlative data analysis showed that a higher degree of hunger correlated negatively with the NET availability of the insular cortex in both obese individuals and HC; however, this finding was more pronounced in obesity. Further, for obese individuals, a negative correlation between disinhibition and NET BP ND of the locus coeruleus was detected. In conclusion, these initial data provide in vivo imaging support for the involvement of the central NE system in maladaptive eating behaviors such as susceptibility to hunger. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Norepinephrine-modified glassy carbon electrode for the simultaneous determination of ascorbic acid and uric acid

    International Nuclear Information System (INIS)

    Zare, H.R.; Memarzadeh, F.; Ardakani, M. Mazloum; Namazian, M.; Golabi, S.M.

    2005-01-01

    The oxidation of norepinephrine (NE) on a preactivated glassy carbon electrode leads to the formation of a deposited layer of about 4.2 x 10 -10 mol cm -2 at the surface of the electrode. The electron transfer rate constant, k s , and charge transfer coefficient, α, for electron transfer between the electrode and immobilized NE film were calculated as 44 s -1 and 0.46, respectively. The NE-modified glassy carbon electrode exhibited good electrocatalytic properties towards ascorbic acid (AA) oxidation in phosphate buffer (pH 7.0) with an overpotential of about 475 mV lower than that of the bare electrode. The electrocatalytic response was evaluated by cyclic voltammetry, chronoamperometry, amperometry and rotating disk voltammetry. The overall number of electrons involved in the catalytic oxidation of AA and the number of electrons involved in the rate-determining step are 2 and 1, respectively. The rate constant for the catalytic oxidation of AA was evaluated by RDE voltammetry and an average value of k h was found to be 8.42 x 10 3 M -1 s -1 . Amperometric determination of AA in stirred solution exhibits a linear range of 2.0-1300.0 μM (correlation coefficient 0.9999) and a detection limit of 0.076 μM. The precision of amperometry was found to be 1.9% for replicate determination of a 49.0 μM solution of AA (n = 6). In differential pulse voltammetric measurements, the NE-modified glassy carbon electrode can separate the AA and uric acid (UA) signals. Ascorbic acid oxidizes at more negative potential than UA. Also, the simultaneous determination of UA and AA is achieved at the NE-modified electrode

  12. Norepinephrine and dopamine increase motility, biofilm formation, and virulence of Vibrio harveyi.

    Science.gov (United States)

    Yang, Qian; Anh, Nguyen D Q; Bossier, Peter; Defoirdt, Tom

    2014-01-01

    Vibrio harveyi is one of the major pathogens of aquatic organisms, affecting both vertebrates and invertebrates, and causes important losses in the aquaculture industry. In order to develop novel methods to control disease caused by this pathogen, we need to obtain a better understanding of pathogenicity mechanisms. Sensing of catecholamines increases both growth and production of virulence-related factors in pathogens of terrestrial animals and humans. However, at this moment, knowledge on the impact of catecholamines on the virulence of pathogens of aquatic organisms is lacking. In the present study, we report that in V. harveyi, norepinephrine (NE) and dopamine (Dopa) increased growth in serum-supplemented medium, siderophore production, swimming motility, and expression of genes involved in flagellar motility, biofilm formation, and exopolysaccharide production. Consistent with this, pretreatment of V. harveyi with catecholamines prior to inoculation into the rearing water resulted in significantly decreased survival of gnotobiotic brine shrimp larvae, when compared to larvae challenged with untreated V. harveyi. Further, NE-induced effects could be neutralized by α-adrenergic antagonists or by the bacterial catecholamine receptor antagonist LED209, but not by β-adrenergic or dopaminergic antagonists. Dopa-induced effects could be neutralized by dopaminergic antagonists or LED209, but not by adrenergic antagonists. Together, our results indicate that catecholamine sensing increases the success of transmission of V. harveyi and that interfering with catecholamine sensing might be an interesting strategy to control vibriosis in aquaculture. We hypothesize that upon tissue and/or hemocyte damage during infection, pathogens come into contact with elevated catecholamine levels, and that this stimulates the expression of virulence factors that are required to colonize a new host.

  13. Selective oxidation of serotonin and norepinephrine over eriochrome cyanine R film modified glassy carbon electrode

    Energy Technology Data Exchange (ETDEWEB)

    Yao Hong; Li Shaoguang [Department of Pharmaceutical Analysis, Faculty of Pharmacy, Fujian Medical University, Fuzhou 350004 (China); Tang Yuhai [Institute of Analytical Sciences, Xi' an Jiaotong University, Xi' an 710061 (China); Chen Yan [Department of Pharmaceutical Analysis, Faculty of Pharmacy, Fujian Medical University, Fuzhou 350004 (China); Chen Yuanzhong [Fujian Institute of Hematology, The Affiliated Union Hospital of Fujian Medical University, Fuzhou 350001 (China)], E-Mail: chenyz@pub3.fz.fj.cn; Lin Xinhua [Department of Pharmaceutical Analysis, Faculty of Pharmacy, Fujian Medical University, Fuzhou 350004 (China)], E-mail: xhlin1963@sin.com

    2009-08-01

    A novel ECR-modified electrode is fabricated by electrodeposition of Eriochrome Cyanine R (ECR) at a glassy carbon (GC) electrode by cyclic voltammetry (CV) in double-distilled water. The characterization of the ECR film modified electrode is carried out by atomic force microscopy (AFM), infrared spectra (IR), spectroelectrochemistry and cyclic voltammetry. The results show that a slightly heterogeneous film formed on the surface of the modified electrode, and the calculated surface concentration of ECR is 2 x 10{sup -10} mol/cm{sup -2}. The ECR film modified GC electrode shows excellent electrocatalytic activities toward the oxidation of serotonin (5-HT) and norepinephrine (NE). Furthermore, the modified electrode can separately detect 5-HT and NE, even in the presence of 200-fold concentration of ascorbic acid (AA) and 25-fold concentration of uric acid (UA). Using differential pulse voltammetry (DPV), the peak currents of 5-HT and NE recorded in pH 7 solution are linearly dependent on their concentrations in the range of 0.05-5 {mu}M and 2-50 {mu}M, respectively. The limits of detection are 0.05 and 1.5 {mu}M for 5-HT and NE, respectively. The ECR film modified electrode can be stored stable for at least 1 week in 0.05 M PBS (pH 7) at 4 {sup o}C in a refrigerator. Owing to its excellent selectivity and sensitivity, the modified electrode could provide a promising tool for the simultaneous determination of 5-HT and NE in complex biosamples.

  14. Effects of a selective iNOS inhibitor versus norepinephrine in the treatment of septic shock.

    Science.gov (United States)

    Su, Fuhong; Huang, Hongchuan; Akieda, Kazuki; Occhipinti, Giovanna; Donadello, Katia; Piagnerelli, Michael; De Backer, Daniel; Vincent, Jean-Louis

    2010-09-01

    Inhibition of NOS is not beneficial in septic shock; selective inhibition of the inducible form (iNOS) may represent a better option. We compared the effects of the selective iNOS inhibitor BYK191023 with those of norepinephrine (NE) in a sheep model of septic shock. Twenty-four anesthetized, mechanically ventilated ewes received 1.5 g/kg body weight of feces into the abdominal cavity to induce sepsis. Animals were randomized into three groups (each n = 8): NE-only, BYK-only, and NE + BYK. The sublingual microcirculation was evaluated with sidestream dark-field videomicroscopy. MAP was higher in the NE + BYK group than in the other groups, but there were no significant differences in cardiac index or systemic vascular resistance. Mean pulmonary arterial pressure was lower in BYK-treated animals than in the NE-only group. PaO2/FiO2 was higher and lactate concentration lower in the BYK groups than in the NE-only group. Mesenteric blood flow was higher in BYK groups than in the NE-only group. Renal blood flow was higher in the NE + BYK group than in the other groups. Functional capillary density and proportion of perfused vessels were higher in the BYK groups than in the NE-only group 18 h after induction of peritonitis. Survival times were similar in the three groups. In this model of peritonitis, selective iNOS inhibition had more beneficial effects than NE on pulmonary artery pressures, gas exchange, mesenteric blood flow, microcirculation, and lactate concentration. Combination of this selective iNOS inhibitor with NE allowed a higher arterial pressure and renal blood flow to be maintained.

  15. Vorinostat increases expression of functional norepinephrine transporter in neuroblastoma in vitro and in vivo model systems

    Science.gov (United States)

    More, Swati S.; Itsara, Melissa; Yang, Xiaodong; Geier, Ethan G.; Tadano, Michelle K.; Seo, Youngho; VanBrocklin, Henry F.; Weiss, William A.; Mueller, Sabine; Haas-Kogan, Daphne A.; DuBois, Steven G.; Matthay, Katherine K.; Giacomini, Kathleen M.

    2011-01-01

    Purpose Histone deacetylase (HDAC) inhibition causes transcriptional activation or repression of several genes that in turn can influence the biodistribution of other chemotherapeutic agents. Here, we hypothesize that the combination of vorinostat, a HDAC inhibitor, with 131I-metaiodobenzylguanidine (MIBG) would lead to preferential accumulation of the latter in neuroblastoma (NB) tumors via increased expression of the human norepinephrine transporter (NET). Experimental Design In vitro and in vivo experiments examined the effect of vorinostat on the expression of NET, an uptake transporter for 131I-MIBG. Human NB cell lines (Kelly and SH-SY-5Y) and NB1691luc mouse xenografts were employed. The upregulated NET protein was characterized for its effect on 123I-MIBG biodistribution. Results Preincubation of NB cell lines, Kelly and SH-SY-5Y, with vorinostat caused dose-dependent increases in NET mRNA and protein levels. Accompanying this was a corresponding dose-dependent increase in MIBG uptake in NB cell lines. Four-fold and 2.5 fold increases were observed in Kelly and SH-SY-5Y cells, respectively, pre-treated with vorinostat in comparison to untreated cells. Similarly, NB xenografts, created by intravenous tail vein injection of NB1691-luc, and harvested from nude mice livers treated with vorinostat (150 mg/kg i.p.) showed substantial increases in NET protein expression. Maximal effect of vorinostat pretreatment in NB xenografts on 123I-MIBG biodistribution was observed in tumors that exhibited enhanced uptake in vorinostat treated (0.062 ± 0.011 μCi/(mg tissue-dose injected)) versus untreated mice (0.022 ± 0.003 μCi/(mg tissue-dose injected); p vorinostat treatment can enhance NB therapy with 131I-MIBG. PMID:21421857

  16. Treatment with clozapine and its effect on plasma homovanillic acid and norepinephrine concentrations in schizophrenia.

    Science.gov (United States)

    Davidson, M; Kahn, R S; Stern, R G; Hirschowitz, J; Apter, S; Knott, P; Davis, K L

    1993-02-01

    Measurement of plasma concentrations of the dopamine metabolite, homovanillic acid (pHVA), is an indirect tool to assess changes in dopamine turnover. Levels of pHVA have been reported to decrease during treatment with conventional antidopaminergic, neuroleptics, with the decrement correlating with symptomatic improvement in schizophrenic symptoms. Clozapine, an atypical neuroleptic, is the only drug proved to be effective in treatment-refractory patients. However, the mechanism mediating this unique efficacy has not been fully elucidated. This study examined the effect of clozapine on pHVA concentrations in schizophrenic patients. Since clozapine potently binds to alpha 2-adrenergic receptors, plasma norepinephrine (pNE) concentrations were also measured. Twenty-eight treatment-refractory schizophrenic patients (24 men, 4 women) were treated with clozapine (up to 600 mg/day) for 5 weeks, after a minimum 1-week drug-free period. Symptomatology and pHVA and pNE concentrations were measured at the last drug-free day and weekly for 5 weeks. Fourteen patients responded to clozapine treatment, while an equal number did not. Mean pHVA concentrations did not significantly change during treatment with clozapine. Although clozapine tended to lower pHVA concentrations in treatment responders, the effect was small and not significant. Clozapine treatment significantly raised pNE concentrations, but this did not differentiate responders from nonresponders to clozapine. These findings suggest that clozapine's effect on DA turnover is small and that clozapine may be effective in treatment-refractory schizophrenia by mechanisms other than, or in addition to, dopamine receptor blockade. However, since about one-third of NE is metabolized into HVA, the clozapine-induced increase in pNE may have overshadowed a possible lowering effect of clozapine on pHVA.

  17. Synaptic membrane rafts: traffic lights for local neurotrophin signaling?

    Science.gov (United States)

    Zonta, Barbara; Minichiello, Liliana

    2013-10-18

    Lipid rafts, cholesterol and lipid rich microdomains, are believed to play important roles as platforms for the partitioning of transmembrane and synaptic proteins involved in synaptic signaling, plasticity, and maintenance. There is increasing evidence of a physical interaction between post-synaptic densities and post-synaptic lipid rafts. Localization of proteins within lipid rafts is highly regulated, and therefore lipid rafts may function as traffic lights modulating and fine-tuning neuronal signaling. The tyrosine kinase neurotrophin receptors (Trk) and the low-affinity p75 neurotrophin receptor (p75(NTR)) are enriched in neuronal lipid rafts together with the intermediates of downstream signaling pathways, suggesting a possible role of rafts in neurotrophin signaling. Moreover, neurotrophins and their receptors are involved in the regulation of cholesterol metabolism. Cholesterol is an important component of lipid rafts and its depletion leads to gradual loss of synapses, underscoring the importance of lipid rafts for proper neuronal function. Here, we review and discuss the idea that translocation of neurotrophin receptors in synaptic rafts may account for the selectivity of their transduced signals.

  18. Synaptic membrane rafts: traffic lights for local neurotrophin signalling?

    Directory of Open Access Journals (Sweden)

    Barbara eZonta

    2013-10-01

    Full Text Available Lipid rafts, cholesterol and lipid rich microdomains, are believed to play important roles as platforms for the partitioning of transmembrane and synaptic proteins involved in synaptic signalling, plasticity and maintenance. There is increasing evidence of a physical interaction between post-synaptic densities and post-synaptic lipid rafts. Localization of proteins within lipid rafts is highly regulated, and therefore lipid rafts may function as traffic lights modulating and fine-tuning neuronal signalling. The tyrosine kinase neurotrophin receptors (Trk and the low-affinity p75 neurotrophin receptor (p75NTR are enriched in neuronal lipid rafts together with the intermediates of downstream signalling pathways, suggesting a possible role of rafts in neurotrophin signalling. Moreover, neurotrophins and their receptors are involved in the regulation of cholesterol metabolism. Cholesterol is an important component of lipid rafts and its depletion leads to gradual loss of synapses, underscoring the importance of lipid rafts for proper neuronal function. Here, we review and discuss the idea that translocation of neurotrophin receptors in synaptic rafts may account for the selectivity of their transduced signals.

  19. Limited distal organelles and synaptic function in extensive monoaminergic innervation.

    Science.gov (United States)

    Tao, Juan; Bulgari, Dinara; Deitcher, David L; Levitan, Edwin S

    2017-08-01

    Organelles such as neuropeptide-containing dense-core vesicles (DCVs) and mitochondria travel down axons to supply synaptic boutons. DCV distribution among en passant boutons in small axonal arbors is mediated by circulation with bidirectional capture. However, it is not known how organelles are distributed in extensive arbors associated with mammalian dopamine neuron vulnerability, and with volume transmission and neuromodulation by monoamines and neuropeptides. Therefore, we studied presynaptic organelle distribution in Drosophila octopamine neurons that innervate ∼20 muscles with ∼1500 boutons. Unlike in smaller arbors, distal boutons in these arbors contain fewer DCVs and mitochondria, although active zones are present. Absence of vesicle circulation is evident by proximal nascent DCV delivery, limited impact of retrograde transport and older distal DCVs. Traffic studies show that DCV axonal transport and synaptic capture are not scaled for extensive innervation, thus limiting distal delivery. Activity-induced synaptic endocytosis and synaptic neuropeptide release are also reduced distally. We propose that limits in organelle transport and synaptic capture compromise distal synapse maintenance and function in extensive axonal arbors, thereby affecting development, plasticity and vulnerability to neurodegenerative disease. © 2017. Published by The Company of Biologists Ltd.

  20. Synaptic contacts impaired by styrene-7,8-oxide toxicity

    International Nuclear Information System (INIS)

    Corsi, P.; D'Aprile, A.; Nico, B.; Costa, G.L.; Assennato, G.

    2007-01-01

    Styrene-7,8-oxide (SO), a chemical compound widely used in industrial applications, is a potential hazard for humans, particularly in occupational settings. Neurobehavioral changes are consistently observed in occupationally exposed individuals and alterations of neurotransmitters associated with neuronal loss have been reported in animal models. Although the toxic effects of styrene have been extensively documented, the molecular mechanisms responsible for SO-induced neurotoxicity are still unclear. A possible dopamine-mediated effect of styrene neurotoxicity has been previously demonstrated, since styrene oxide alters dopamine neurotransmission in the brain. Thus, the present study hypothesizes that styrene neurotoxicity may involve synaptic contacts. Primary striatal neurons were exposed to styrene oxide at different concentrations (0.1-1 mM) for different time periods (8, 16, and 24 h) to evaluate the dose able to induce synaptic impairments. The expression of proteins crucial for synaptic transmission such as Synapsin, Synaptophysin, and RAC-1 were considered. The levels of Synaptophysin and RAC-1 decreased in a dose-dependent manner. Accordingly, morphological alterations, observed at the ultrastructural level, primarily involved the pre-synaptic compartment. In SO-exposed cultures, the biochemical cascade of caspases was activated affecting the cytoskeleton components as their target. Thus the impairments in synaptic contacts observed in SO-exposed cultures might reflect a primarily morphological alteration of neuronal cytoskeleton. In addition, our data support the hypothesis developed by previous authors of reactive oxygen species (ROS) initiating events of SO cytotoxicity

  1. Readily releasable pool of synaptic vesicles measured at single synaptic contacts.

    Science.gov (United States)

    Trigo, Federico F; Sakaba, Takeshi; Ogden, David; Marty, Alain

    2012-10-30

    To distinguish between different models of vesicular release in brain synapses, it is necessary to know the number of vesicles of transmitter that can be released immediately at individual synapses by a high-calcium stimulus, the readily releasable pool (RRP). We used direct stimulation by calcium uncaging at identified, single-site inhibitory synapses to investigate the statistics of vesicular release and the size of the RRP. Vesicular release, detected as quantal responses in the postsynaptic neuron, showed an unexpected stochastic variation in the number of quanta from stimulus to stimulus at high intracellular calcium, with a mean of 1.9 per stimulus and a maximum of three or four. The results provide direct measurement of the RRP at single synaptic sites. They are consistent with models in which release proceeds from a small number of vesicle docking sites with an average occupancy around 0.7.

  2. Enabling graphene nanoelectronics.

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Wei; Ohta, Taisuke; Biedermann, Laura Butler; Gutierrez, Carlos; Nolen, C. M.; Howell, Stephen Wayne; Beechem Iii, Thomas Edwin; McCarty, Kevin F.; Ross, Anthony Joseph, III

    2011-09-01

    Recent work has shown that graphene, a 2D electronic material amenable to the planar semiconductor fabrication processing, possesses tunable electronic material properties potentially far superior to metals and other standard semiconductors. Despite its phenomenal electronic properties, focused research is still required to develop techniques for depositing and synthesizing graphene over large areas, thereby enabling the reproducible mass-fabrication of graphene-based devices. To address these issues, we combined an array of growth approaches and characterization resources to investigate several innovative and synergistic approaches for the synthesis of high quality graphene films on technologically relevant substrate (SiC and metals). Our work focused on developing the fundamental scientific understanding necessary to generate large-area graphene films that exhibit highly uniform electronic properties and record carrier mobility, as well as developing techniques to transfer graphene onto other substrates.

  3. Synaptic proteins and receptors defects in autism spectrum disorders

    Directory of Open Access Journals (Sweden)

    Jianling eChen

    2014-09-01

    Full Text Available Recent studies have found that hundreds of genetic variants, including common and rare variants, rare and de novo mutations, and common polymorphisms have contributed to the occurrence of autism spectrum disorders (ASDs. The mutations in a number of genes such as neurexin, neuroligin, postsynaptic density protein 95 (PSD-95, SH3 and multiple ankyrin repeat domains 3 (SHANK3, synapsin, gephyrin, cadherin (CDH and protocadherin (PCDH, thousand-and-one-amino acid 2 kinase (TAOK2, and contactin (CNTN, have been shown to play important roles in the development and function of synapses. In addition, synaptic receptors, such as gamma-aminobutyric acid (GABA receptors and glutamate receptors, have also been associated with ASDs. This review will primarily focus on the defects of synaptic proteins and receptors associated with ASDs and their roles in the pathogenesis of ASDs via synaptic pathways.

  4. Interregional synaptic maps among engram cells underlie memory formation.

    Science.gov (United States)

    Choi, Jun-Hyeok; Sim, Su-Eon; Kim, Ji-Il; Choi, Dong Il; Oh, Jihae; Ye, Sanghyun; Lee, Jaehyun; Kim, TaeHyun; Ko, Hyoung-Gon; Lim, Chae-Seok; Kaang, Bong-Kiun

    2018-04-27

    Memory resides in engram cells distributed across the brain. However, the site-specific substrate within these engram cells remains theoretical, even though it is generally accepted that synaptic plasticity encodes memories. We developed the dual-eGRASP (green fluorescent protein reconstitution across synaptic partners) technique to examine synapses between engram cells to identify the specific neuronal site for memory storage. We found an increased number and size of spines on CA1 engram cells receiving input from CA3 engram cells. In contextual fear conditioning, this enhanced connectivity between engram cells encoded memory strength. CA3 engram to CA1 engram projections strongly occluded long-term potentiation. These results indicate that enhanced structural and functional connectivity between engram cells across two directly connected brain regions forms the synaptic correlate for memory formation. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

  5. PRRT2: from Paroxysmal Disorders to Regulation of Synaptic Function.

    Science.gov (United States)

    Valtorta, Flavia; Benfenati, Fabio; Zara, Federico; Meldolesi, Jacopo

    2016-10-01

    In the past few years, proline-rich transmembrane protein (PRRT)2 has been identified as the causative gene for several paroxysmal neurological disorders. Recently, an important role of PRRT2 in synapse development and function has emerged. Knock down of the protein strongly impairs the formation of synaptic contacts and neurotransmitter release. At the nerve terminal, PRRT2 endows synaptic vesicle exocytosis with Ca 2+ sensitivity by interacting with proteins of the fusion complex and with the Ca 2+ sensors synaptotagmins (Syts). In the postsynaptic compartment, PRRT2 interacts with glutamate receptors. The study of PRRT2 and of its mutations may help in refining our knowledge of the process of synaptic transmission and elucidating the pathogenetic mechanisms leading to derangement of network function in paroxysmal disorders. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Synaptic clustering within dendrites: an emerging theory of memory formation

    Science.gov (United States)

    Kastellakis, George; Cai, Denise J.; Mednick, Sara C.; Silva, Alcino J.; Poirazi, Panayiota

    2015-01-01

    It is generally accepted that complex memories are stored in distributed representations throughout the brain, however the mechanisms underlying these representations are not understood. Here, we review recent findings regarding the subcellular mechanisms implicated in memory formation, which provide evidence for a dendrite-centered theory of memory. Plasticity-related phenomena which affect synaptic properties, such as synaptic tagging and capture, synaptic clustering, branch strength potentiation and spinogenesis provide the foundation for a model of memory storage that relies heavily on processes operating at the dendrite level. The emerging picture suggests that clusters of functionally related synapses may serve as key computational and memory storage units in the brain. We discuss both experimental evidence and theoretical models that support this hypothesis and explore its advantages for neuronal function. PMID:25576663

  7. Defective glycinergic synaptic transmission in zebrafish motility mutants

    Directory of Open Access Journals (Sweden)

    Hiromi Hirata

    2010-01-01

    Full Text Available Glycine is a major inhibitory neurotransmitter in the spinal cord and brainstem. Recently, in vivo analysis of glycinergic synaptic transmission has been pursued in zebrafish using molecular genetics. An ENU mutagenesis screen identified two behavioral mutants that are defective in glycinergic synaptic transmission. Zebrafish bandoneon (beo mutants have a defect in glrbb, one of the duplicated glycine receptor (GlyR β subunit genes. These mutants exhibit a loss of glycinergic synaptic transmission due to a lack of synaptic aggregation of GlyRs. Due to the consequent loss of reciprocal inhibition of motor circuits between the two sides of the spinal cord, motor neurons activate simultaneously on both sides resulting in bilateral contraction of axial muscles of beo mutants, eliciting the so-called ‘accordion’ phenotype. Similar defects in GlyR subunit genes have been observed in several mammals and are the basis for human hyperekplexia/startle disease. By contrast, zebrafish shocked (sho mutants have a defect in slc6a9, encoding GlyT1, a glycine transporter that is expressed by astroglial cells surrounding the glycinergic synapse in the hindbrain and spinal cord. GlyT1 mediates rapid uptake of glycine from the synaptic cleft, terminating synaptic transmission. In zebrafish sho mutants, there appears to be elevated extracellular glycine resulting in persistent inhibition of postsynaptic neurons and subsequent reduced motility, causing the ‘twitch once’ phenotype. We review current knowledge regarding zebrafish ‘accordion’ and ‘twitch once’ mutants, including beo and sho, and report the identification of a new α2 subunit that revises the phylogeny of zebrafish GlyRs.

  8. Precise synaptic efficacy alignment suggests potentiation dominated learning

    Directory of Open Access Journals (Sweden)

    Christoph eHartmann

    2016-01-01

    Full Text Available Recent evidence suggests that parallel synapses from the same axonal branch onto the same dendritic branch have almost identical strength. It has been proposed that this alignment is only possible through learning rules that integrate activity over long time spans. However, learning mechanisms such as spike-timing-dependent plasticity (STDP are commonly assumed to be temporally local. Here, we propose that the combination of temporally local STDP and a multiplicative synaptic normalization mechanism is sufficient to explain the alignment of parallel synapses.To address this issue, we introduce three increasingly complex models: First, we model the idealized interaction of STDP and synaptic normalization in a single neuron as a simple stochastic process and derive analytically that the alignment effect can be described by a so-called Kesten process. From this we can derive that synaptic efficacy alignment requires potentiation-dominated learning regimes. We verify these conditions in a single-neuron model with independent spiking activities but more realistic synapses. As expected, we only observe synaptic efficacy alignment for long-term potentiation-biased STDP. Finally, we explore how well the findings transfer to recurrent neural networks where the learning mechanisms interact with the correlated activity of the network. We find that due to the self-reinforcing correlations in recurrent circuits under STDP, alignment occurs for both long-term potentiation- and depression-biased STDP, because the learning will be potentiation dominated in both cases due to the potentiating events induced by correlated activity. This is in line with recent results demonstrating a dominance of potentiation over depression during waking and normalization during sleep. This leads us to predict that individual spine pairs will be more similar in the morning than they are after sleep depriviation.In conclusion, we show that synaptic normalization in conjunction with

  9. Emergence of Functional Specificity in Balanced Networks with Synaptic Plasticity.

    Directory of Open Access Journals (Sweden)

    Sadra Sadeh

    2015-06-01

    Full Text Available In rodent visual cortex, synaptic connections between orientation-selective neurons are unspecific at the time of eye opening, and become to some degree functionally specific only later during development. An explanation for this two-stage process was proposed in terms of Hebbian plasticity based on visual experience that would eventually enhance connections between neurons with similar response features. For this to work, however, two conditions must be satisfied: First, orientation selective neuronal responses must exist before specific recurrent synaptic connections can be established. Second, Hebbian learning must be compatible with the recurrent network dynamics contributing to orientation selectivity, and the resulting specific connectivity must remain stable for unspecific background activity. Previous studies have mainly focused on very simple models, where the receptive fields of neurons were essentially determined by feedforward mechanisms, and where the recurrent network was small, lacking the complex recurrent dynamics of large-scale networks of excitatory and inhibitory neurons. Here we studied the emergence of functionally specific connectivity in large-scale recurrent networks with synaptic plasticity. Our results show that balanced random networks, which already exhibit highly selective responses at eye opening, can develop feature-specific connectivity if appropriate rules of synaptic plasticity are invoked within and between excitatory and inhibitory populations. If these conditions are met, the initial orientation selectivity guides the process of Hebbian learning and, as a result, functionally specific and a surplus of bidirectional connections emerge. Our results thus demonstrate the cooperation of synaptic plasticity and recurrent dynamics in large-scale functional networks with realistic receptive fields, highlight the role of inhibition as a critical element in this process, and paves the road for further computational

  10. Depression as a Glial-Based Synaptic Dysfunction

    Directory of Open Access Journals (Sweden)

    Daniel eRial

    2016-01-01

    Full Text Available Recent studies combining pharmacological, behavioral, electrophysiological and molecular approaches indicate that depression results from maladaptive neuroplastic processing occurring in defined frontolimbic circuits responsible for emotional processing such as the prefrontal cortex, hippocampus, amygdala and ventral striatum. However, the exact mechanisms controlling synaptic plasticity that are disrupted to trigger depressive conditions have not been elucidated. Since glial cells (astrocytes and microglia tightly and dynamically interact with synapses, engaging a bi-directional communication critical for the processing of synaptic information, we now revisit the role of glial cells in the etiology of depression focusing on a dysfunction of the ‘quad-partite’ synapse. This interest is supported by the observations that depressive-like conditions are associated with a decreased density and hypofunction of astrocytes and with an increase microglia ‘activation’ in frontolimbic regions, which is expected to contribute for the synaptic dysfunction present in depression. Furthermore, the traditional culprits of depression (glucocorticoids, biogenic amines, BDNF affect glia functioning, whereas antidepressant treatments (SSRIs, electroshock, deep brain stimulation recover glia functioning. In this context of a quad-partite synapse, systems modulating glia-synapse bidirectional communication - such as the purinergic neuromodulation system operated by ATP and adenosine - emerge as promising candidates to re-normalize synaptic function by combining direct synaptic effects with an ability to also control astrocyte and microglia function. This proposed triple action of purines to control aberrant synaptic function illustrates the rationale to consider the interference with glia dysfunction as a mechanism of action driving the design of future pharmacological tools to manage depression.

  11. Defective Glycinergic Synaptic Transmission in Zebrafish Motility Mutants

    Science.gov (United States)

    Hirata, Hiromi; Carta, Eloisa; Yamanaka, Iori; Harvey, Robert J.; Kuwada, John Y.

    2009-01-01

    Glycine is a major inhibitory neurotransmitter in the spinal cord and brainstem. Recently, in vivo analysis of glycinergic synaptic transmission has been pursued in zebrafish using molecular genetics. An ENU mutagenesis screen identified two behavioral mutants that are defective in glycinergic synaptic transmission. Zebrafish bandoneon (beo) mutants have a defect in glrbb, one of the duplicated glycine receptor (GlyR) β subunit genes. These mutants exhibit a loss of glycinergic synaptic transmission due to a lack of synaptic aggregation of GlyRs. Due to the consequent loss of reciprocal inhibition of motor circuits between the two sides of the spinal cord, motor neurons activate simultaneously on both sides resulting in bilateral contraction of axial muscles of beo mutants, eliciting the so-called ‘accordion’ phenotype. Similar defects in GlyR subunit genes have been observed in several mammals and are the basis for human hyperekplexia/startle disease. By contrast, zebrafish shocked (sho) mutants have a defect in slc6a9, encoding GlyT1, a glycine transporter that is expressed by astroglial cells surrounding the glycinergic synapse in the hindbrain and spinal cord. GlyT1 mediates rapid uptake of glycine from the synaptic cleft, terminating synaptic transmission. In zebrafish sho mutants, there appears to be elevated extracellular glycine resulting in persistent inhibition of postsynaptic neurons and subsequent reduced motility, causing the ‘twitch-once’ phenotype. We review current knowledge regarding zebrafish ‘accordion’ and ‘twitch-once’ mutants, including beo and sho, and report the identification of a new α2 subunit that revises the phylogeny of zebrafish GlyRs. PMID:20161699

  12. Hardwiring of fine synaptic layers in the zebrafish visual pathway

    Directory of Open Access Journals (Sweden)

    Taylor Michael R

    2008-12-01

    Full Text Available Abstract Background Neuronal connections are often arranged in layers, which are divided into sublaminae harboring synapses with similar response properties. It is still debated how fine-grained synaptic layering is established during development. Here we investigated two stratified areas of the zebrafish visual pathway, the inner plexiform layer (IPL of the retina and the neuropil of the optic tectum, and determined if activity is required for their organization. Results The IPL of 5-day-old zebrafish larvae is composed of at least nine sublaminae, comprising the connections between different types of amacrine, bipolar, and ganglion cells (ACs, BCs, GCs. These sublaminae were distinguished by their expression of cell type-specific transgenic fluorescent reporters and immunohistochemical markers, including protein kinase Cβ (PKC, parvalbumin (Parv, zrf3, and choline acetyltransferase (ChAT. In the tectum, four retinal input layers abut a laminated array of neurites of tectal cells, which differentially express PKC and Parv. We investigated whether these patterns were affected by experimental disruptions of retinal activity in developing fish. Neither elimination of light inputs by dark rearing, nor a D, L-amino-phosphono-butyrate-induced reduction in the retinal response to light onset (but not offset altered IPL or tectal lamination. Moreover, thorough elimination of chemical synaptic transmission with Botulinum toxin B left laminar synaptic arrays intact. Conclusion Our results call into question a role for activity-dependent mechanisms – instructive light signals, balanced on and off BC activity, Hebbian plasticity, or a permissive role for synaptic transmission – in the synaptic stratification we examined. We propose that genetically encoded cues are sufficient to target groups of neurites to synaptic layers in this vertebrate visual system.

  13. Synaptic model for spontaneous activity in developing networks

    DEFF Research Database (Denmark)

    Lerchner, Alexander; Rinzel, J.

    2005-01-01

    Spontaneous rhythmic activity occurs in many developing neural networks. The activity in these hyperexcitable networks is comprised of recurring "episodes" consisting of "cycles" of high activity that alternate with "silent phases" with little or no activity. We introduce a new model of synaptic...... dynamics that takes into account that only a fraction of the vesicles stored in a synaptic terminal is readily available for release. We show that our model can reproduce spontaneous rhythmic activity with the same general features as observed in experiments, including a positive correlation between...

  14. Grid-Enabled Measures

    Science.gov (United States)

    Moser, Richard P.; Hesse, Bradford W.; Shaikh, Abdul R.; Courtney, Paul; Morgan, Glen; Augustson, Erik; Kobrin, Sarah; Levin, Kerry; Helba, Cynthia; Garner, David; Dunn, Marsha; Coa, Kisha

    2011-01-01

    Scientists are taking advantage of the Internet and collaborative web technology to accelerate discovery in a massively connected, participative environment —a phenomenon referred to by some as Science 2.0. As a new way of doing science, this phenomenon has the potential to push science forward in a more efficient manner than was previously possible. The Grid-Enabled Measures (GEM) database has been conceptualized as an instantiation of Science 2.0 principles by the National Cancer Institute with two overarching goals: (1) Promote the use of standardized measures, which are tied to theoretically based constructs; and (2) Facilitate the ability to share harmonized data resulting from the use of standardized measures. This is done by creating an online venue connected to the Cancer Biomedical Informatics Grid (caBIG®) where a virtual community of researchers can collaborate together and come to consensus on measures by rating, commenting and viewing meta-data about the measures and associated constructs. This paper will describe the web 2.0 principles on which the GEM database is based, describe its functionality, and discuss some of the important issues involved with creating the GEM database, such as the role of mutually agreed-on ontologies (i.e., knowledge categories and the relationships among these categories— for data sharing). PMID:21521586

  15. Enabling distributed petascale science

    International Nuclear Information System (INIS)

    Baranovski, Andrew; Bharathi, Shishir; Bresnahan, John

    2007-01-01

    Petascale science is an end-to-end endeavour, involving not only the creation of massive datasets at supercomputers or experimental facilities, but the subsequent analysis of that data by a user community that may be distributed across many laboratories and universities. The new SciDAC Center for Enabling Distributed Petascale Science (CEDPS) is developing tools to support this end-to-end process. These tools include data placement services for the reliable, high-performance, secure, and policy-driven placement of data within a distributed science environment; tools and techniques for the construction, operation, and provisioning of scalable science services; and tools for the detection and diagnosis of failures in end-to-end data placement and distributed application hosting configurations. In each area, we build on a strong base of existing technology and have made useful progress in the first year of the project. For example, we have recently achieved order-of-magnitude improvements in transfer times (for lots of small files) and implemented asynchronous data staging capabilities; demonstrated dynamic deployment of complex application stacks for the STAR experiment; and designed and deployed end-to-end troubleshooting services. We look forward to working with SciDAC application and technology projects to realize the promise of petascale science

  16. Enabling immersive simulation.

    Energy Technology Data Exchange (ETDEWEB)

    McCoy, Josh (University of California Santa Cruz, Santa Cruz, CA); Mateas, Michael (University of California Santa Cruz, Santa Cruz, CA); Hart, Derek H.; Whetzel, Jonathan; Basilico, Justin Derrick; Glickman, Matthew R.; Abbott, Robert G.

    2009-02-01

    The object of the 'Enabling Immersive Simulation for Complex Systems Analysis and Training' LDRD has been to research, design, and engineer a capability to develop simulations which (1) provide a rich, immersive interface for participation by real humans (exploiting existing high-performance game-engine technology wherever possible), and (2) can leverage Sandia's substantial investment in high-fidelity physical and cognitive models implemented in the Umbra simulation framework. We report here on these efforts. First, we describe the integration of Sandia's Umbra modular simulation framework with the open-source Delta3D game engine. Next, we report on Umbra's integration with Sandia's Cognitive Foundry, specifically to provide for learning behaviors for 'virtual teammates' directly from observed human behavior. Finally, we describe the integration of Delta3D with the ABL behavior engine, and report on research into establishing the theoretical framework that will be required to make use of tools like ABL to scale up to increasingly rich and realistic virtual characters.

  17. Displays enabling mobile multimedia

    Science.gov (United States)

    Kimmel, Jyrki

    2007-02-01

    With the rapid advances in telecommunications networks, mobile multimedia delivery to handsets is now a reality. While a truly immersive multimedia experience is still far ahead in the mobile world, significant advances have been made in the constituent audio-visual technologies to make this become possible. One of the critical components in multimedia delivery is the mobile handset display. While such alternatives as headset-style near-to-eye displays, autostereoscopic displays, mini-projectors, and roll-out flexible displays can deliver either a larger virtual screen size than the pocketable dimensions of the mobile device can offer, or an added degree of immersion by adding the illusion of the third dimension in the viewing experience, there are still challenges in the full deployment of such displays in real-life mobile communication terminals. Meanwhile, direct-view display technologies have developed steadily, and can provide a development platform for an even better viewing experience for multimedia in the near future. The paper presents an overview of the mobile display technology space with an emphasis on the advances and potential in developing direct-view displays further to meet the goal of enabling multimedia in the mobile domain.

  18. Selective binding of 2-[{sup 125}I]iodo-nisoxetine to norepinephrine transporters in the brain

    Energy Technology Data Exchange (ETDEWEB)

    Kung, M.-P.; Choi, Seok-Rye; Hou, Catherine; Zhuang, Z.-P.; Foulon, Catherine; Kung, Hank F. E-mail: kunghf@sunmac.spect.upenn.edu

    2004-07-01

    A radioiodinated ligand, (R)-N-methyl-(2-[{sup 125}I]iodo-phenoxy)-3-phenylpropylamine, [{sup 125}I]2-INXT, targeting norepinephrine transporters (NET), was successfully prepared. A no-carrier-added product, [{sup 125}I]2-INXT, displayed a saturable binding with a high affinity (K{sub d}=0.06 nM) in the homogenates prepared from rat cortical tissues as well as from LLC-PK{sub 1} cells expressing NET. A relatively low number of binding sties (B{sub max}=55 fmol/mg protein) measured with [{sup 125}I]2-INXT in rat cortical homogenates is consistent with the value reported for a known NET ligand, [{sup 3}H]nisoxetine. Competition studies with various compounds on [{sup 125}I]2-INXT binding clearly confirmed the pharmacological specificity and selectivity for NET binding sites. Following a tail-vein injection of [{sup 125}I]2-INXT in rats, a good initial brain uptake was observed (0.56% dose at 2 min) followed by a slow washout from the brain (0.2% remained at 3 hours post-injection). The hypothalamus (a NET-rich region) to striatum (a region devoid of NET) ratio was 1.5 at 3 hours post-i.v. injection. Pretreatment of rats with nisoxetine significantly inhibited the uptake of [{sup 125}I]2-INXT (70-100% inhibition) in locus coeruleus, hypothalamus and raphe nuclei, regions known to have a high density of NET; whereas escitalopram, a serotonin transporter ligand, did not show a similar effect. Ex vivo autoradiography of rat brain sections of [{sup 125}I]2-INXT (at 3 hours after an i.v. injection) displayed an excellent regional brain localization pattern corroborated to the specific NET distribution in the brain. The specific brain localization was significantly reduced by a dose of nisoxetine pretreatment. Taken together, the data suggest that [{sup 123}I]2-INXT may be useful for mapping NET binding sites in the brain.

  19. Age-related differences in norepinephrine kinetics: Effect of posture and sodium-restricted diet

    International Nuclear Information System (INIS)

    Supiano, M.A.; Linares, O.A.; Smith, M.J.; Halter, J.B.

    1990-01-01

    We used compartmental analysis to study the influence of age on the kinetics of norepinephrine (NE) distribution and metabolism. Plasma NE and [3H]NE levels were measured in 10 young (age 19-33 yr) and 13 elderly (age 62-73 yr) subjects in the basal supine position, during upright posture, and after 1 wk of a sodium-restricted diet. We found that the basal supine release rate of NE into the extravascular compartment, which is the site of endogenous NE release (NE2), was significantly increased in the elderly group (young, 9.6 +/- 0.5; elderly, 12.3 +/- 0.8 nmol.min-1.m-2; means +/- SE; P = 0.016), providing direct evidence for an age-related increase in sympathetic nervous system (SNS) tone. Although upright posture led to a greater increase in plasma NE in the young (0.90 +/- 0.07 to 2.36 +/- 0.16 nM) than in the elderly (1.31 +/- 0.11 to 2.56 +/- 0.31 nM; age group-posture interaction, P = 0.02), the increase in NE2 was similar between the young (9.6 +/- 0.6 to 16.2 +/- 1.5 nmol.min-1.m-2) and the elderly (11.6 +/- 1.4 to 16.1 +/- 2.4 nmol.min-1.m-2; posture effect, P = 0.001; age group-posture interaction, P = 0.15). Thus the increase in SNS tone resulting from upright posture was similar in young and elderly subjects. Plasma NE levels increased similarly in both groups after a sodium-restricted diet (diet effect, P = 0.001; age group-diet interaction, P = 0.23). However, NE2 did not increase significantly in either group (diet effect, P = 0.26), suggesting that SNS tone did not increase after a sodium-restricted diet. Compartmental analysis provides a description of age-related differences in NE kinetics, including an age-related increase in the extravascular NE release rate

  20. The norepinephrine transporter in attention-deficit/hyperactivity disorder investigated with positron emission tomography.

    Science.gov (United States)

    Vanicek, Thomas; Spies, Marie; Rami-Mark, Christina; Savli, Markus; Höflich, Anna; Kranz, Georg S; Hahn, Andreas; Kutzelnigg, Alexandra; Traub-Weidinger, Tatjana; Mitterhauser, Markus; Wadsak, Wolfgang; Hacker, Marcus; Volkow, Nora D; Kasper, Siegfried; Lanzenberger, Rupert

    2014-12-01

    Attention-deficit/hyperactivity disorder (ADHD) research has long focused on the dopaminergic system's contribution to pathogenesis, although the results have been inconclusive. However, a case has been made for the involvement of the noradrenergic system, which modulates cognitive processes, such as arousal, working memory, and response inhibition, all of which are typically affected in ADHD. Furthermore, the norepinephrine transporter (NET) is an important target for frequently prescribed medication in ADHD. Therefore, the NET is suggested to play a critical role in ADHD. To explore the differences in NET nondisplaceable binding potential (NET BPND) using positron emission tomography and the highly selective radioligand (S,S)-[18F]FMeNER-D2 [(S,S)-2-(α-(2-[18F]fluoro[2H2]methoxyphenoxy)benzyl)morpholine] between adults with ADHD and healthy volunteers serving as controls. Twenty-two medication-free patients with ADHD (mean [SD] age, 30.7 [10.4] years; 15 [68%] men) without psychiatric comorbidities and 22 age- and sex-matched healthy controls (30.9 [10.6] years; 15 [68%] men) underwent positron emission tomography once. A linear mixed model was used to compare NET BPND between groups. The NET BPND in selected regions of interest relevant for ADHD, including the hippocampus, putamen, pallidum, thalamus, midbrain with pons (comprising a region of interest that includes the locus coeruleus), and cerebellum. In addition, the NET BPND was evaluated in thalamic subnuclei (13 atlas-based regions of interest). We found no significant differences in NET availability or regional distribution between patients with ADHD and healthy controls in all investigated brain regions (F1,41sex nor smoking status influenced NET availability. We determined a significant negative correlation between age and NET availability in the thalamus (R2=0.29; P<.01 corrected) and midbrain with pons, including the locus coeruleus (R2=0.18; P<.01 corrected), which corroborates prior findings of a

  1. The Norepinephrine Transporter in Attention-Deficit/Hyperactivity Disorder Investigated With Positron Emission Tomography

    Science.gov (United States)

    Rami-Mark, Christina; Savli, Markus; Höflich, Anna; Kranz, Georg S.; Hahn, Andreas; Kutzelnigg, Alexandra; Traub-Weidinger, Tatjana; Mitterhauser, Markus; Wadsak, Wolfgang; Hacker, Marcus; Volkow, Nora D.; Kasper, Siegfried; Lanzenberger, Rupert

    2015-01-01

    IMPORTANCE Attention-deficit/hyperactivity disorder (ADHD) research has long focused on the dopaminergic system’s contribution to pathogenesis, although the results have been inconclusive. However, a case has been made for the involvement of the noradrenergic system, which modulates cognitive processes, such as arousal, working memory, and response inhibition, all of which are typically affected in ADHD. Furthermore, the norepinephrine transporter (NET) is an important target for frequently prescribed medication in ADHD. Therefore, the NET is suggested to play a critical role in ADHD. OBJECTIVE To explore the differences in NET nondisplaceable binding potential (NET BPND) using positron emission tomography and the highly selective radioligand (S,S)-[18F]FMeNER-D2 [(S,S)-2-(α-(2-[18F]fluoro[2H2]methoxyphenoxy)benzyl)morpholine] between adults with ADHD and healthy volunteers serving as controls. DESIGN, SETTING, AND PARTICIPANTS Twenty-two medication-free patients with ADHD (mean [SD] age, 30.7 [10.4] years; 15 [68%] men) without psychiatric comorbidities and 22 age- and sex-matched healthy controls (30.9 [10.6] years; 15 [68%] men) underwent positron emission tomography once. A linear mixed model was used to compare NET BPND between groups. MAIN OUTCOMES AND MEASURES The NET BPND in selected regions of interest relevant for ADHD, including the hippocampus, putamen, pallidum, thalamus, midbrain with pons (comprising a region of interest that includes the locus coeruleus), and cerebellum. In addition, the NET BPND was evaluated in thalamic subnuclei (13 atlas-based regions of interest). RESULTS We found no significant differences in NET availability or regional distribution between patients with ADHD and healthy controls in all investigated brain regions (F1,41 < 0.01; P = .96). Furthermore, we identified no significant association between ADHD symptom severity and regional NET availability. Neither sex nor smoking status influenced NET availability. We determined

  2. Sympathetic nervous activity and renal and systemic hemodynamics in cirrhosis: plasma norepinephrine concentration, hepatic extraction, and renal release

    DEFF Research Database (Denmark)

    Ring-Larsen, H; Hesse, B; Henriksen, Jens Henrik Sahl

    1982-01-01

    as previously reported in healthy controls. The right kidney released NE into the systemic circulation. Renal venous plasma NE exceeded arterial concentration by 34% (p less than 0.01). It is concluded that sympathetic nervous activity is enhanced in patients with cirrhosis, and that this hyperactivity may...... in patients than controls (82 vs. 95 mm Hg, p less than 0.05) but did not change during the tilt. Plasma norepinephrine (NE) concentration was significantly higher in another eight patients with cirrhosis than in eight healthy controls (mean: 0.45 vs. 0.21 ng per ml in recumbency, p less than 0.02). Following...

  3. Synaptic excitation in spinal motoneurons alternates with synaptic inhibition and is balanced by outward rectification during rhythmic motor network activity

    DEFF Research Database (Denmark)

    Guzulaitis, Robertas; Hounsgaard, Jorn

    2017-01-01

    channels. Intrinsic outward rectification facilitates spiking by focusing synaptic depolarization near threshold for action potentials. By direct recording of synaptic currents, we also show that motoneurons are activated by out-of-phase peaks in excitation and inhibition during network activity, whereas......Regular firing in spinal motoneurons of red-eared turtles (Trachemys scripta elegans, either sex) evoked by steady depolarization at rest is replaced by irregular firing during functional network activity. The transition caused by increased input conductance and synaptic fluctuations in membrane...... potential was suggested to originate from intense concurrent inhibition and excitation. We show that the conductance increase in motoneurons during functional network activity is mainly caused by intrinsic outward rectification near threshold for action potentials by activation of voltage and Ca2+ gated K...

  4. Enabling cleanup technology transfer

    International Nuclear Information System (INIS)

    Ditmars, J. D.

    2002-01-01

    Technology transfer in the environmental restoration, or cleanup, area has been challenging. While there is little doubt that innovative technologies are needed to reduce the times, risks, and costs associated with the cleanup of federal sites, particularly those of the Departments of Energy (DOE) and Defense, the use of such technologies in actual cleanups has been relatively limited. There are, of course, many reasons why technologies do not reach the implementation phase or do not get transferred from developing entities to the user community. For example, many past cleanup contracts provided few incentives for performance that would compel a contractor to seek improvement via technology applications. While performance-based contracts are becoming more common, they alone will not drive increased technology applications. This paper focuses on some applications of cleanup methodologies and technologies that have been successful and are illustrative of a more general principle. The principle is at once obvious and not widely practiced. It is that, with few exceptions, innovative cleanup technologies are rarely implemented successfully alone but rather are implemented in the context of enabling processes and methodologies. And, since cleanup is conducted in a regulatory environment, the stage is better set for technology transfer when the context includes substantive interactions with the relevant stakeholders. Examples of this principle are drawn from Argonne National Laboratory's experiences in Adaptive Sampling and Analysis Programs (ASAPs), Precise Excavation, and the DOE Technology Connection (TechCon) Program. The lessons learned may be applicable to the continuing challenges posed by the cleanup and long-term stewardship of radioactive contaminants and unexploded ordnance (UXO) at federal sites

  5. Spike Pattern Structure Influences Synaptic Efficacy Variability Under STDP and Synaptic Homeostasis. I: Spike Generating Models on Converging Motifs

    Directory of Open Access Journals (Sweden)

    Zedong eBi

    2016-02-01

    Full Text Available In neural systems, synaptic plasticity is usually driven by spike trains. Due to the inherent noises of neurons and synapses as well as the randomness of connection details, spike trains typically exhibit variability such as spatial randomness and temporal stochasticity, resulting in variability of synaptic changes under plasticity, which we call efficacy variability. How the variability of spike trains influences the efficacy variability of synapses remains unclear. In this paper, we try to understand this influence under pair-wise additive spike-timing dependent plasticity (STDP when the mean strength of plastic synapses into a neuron is bounded (synaptic homeostasis. Specifically, we systematically study, analytically and numerically, how four aspects of statistical features, i.e. synchronous firing, burstiness/regularity, heterogeneity of rates and heterogeneity of cross-correlations, as well as their interactions influence the efficacy variability in converging motifs (simple networks in which one neuron receives from many other neurons. Neurons (including the post-synaptic neuron in a converging motif generate spikes according to statistical models with tunable parameters. In this way, we can explicitly control the statistics of the spike patterns, and investigate their influence onto the efficacy variability, without worrying about the feedback from synaptic changes onto the dynamics of the post-synaptic neuron. We separate efficacy variability into two parts: the drift part (DriftV induced by the heterogeneity of change rates of different synapses, and the diffusion part (DiffV induced by weight diffusion caused by stochasticity of spike trains. Our main findings are: (1 synchronous firing and burstiness tend to increase DiffV, (2 heterogeneity of rates induces DriftV when potentiation and depression in STDP are not balanced, and (3 heterogeneity of cross-correlations induces DriftV together with heterogeneity of rates. We anticipate our

  6. Targeting of NF-κB to Dendritic Spines Is Required for Synaptic Signaling and Spine Development.

    Science.gov (United States)

    Dresselhaus, Erica C; Boersma, Matthew C H; Meffert, Mollie K

    2018-04-25

    Long-term forms of brain plasticity share a requirement for changes in gene expression induced by neuronal activity. Mechanisms that determine how the distinct and overlapping functions of multiple activity-responsive transcription factors, including nuclear factor κB (NF-κB), give rise to stimulus-appropriate neuronal responses remain unclear. We report that the p65/RelA subunit of NF-κB confers subcellular enrichment at neuronal dendritic spines and engineer a p65 mutant that lacks spine enrichment (p65ΔSE) but retains inherent transcriptional activity equivalent to wild-type p65. Wild-type p65 or p65ΔSE both rescue NF-κB-dependent gene expression in p65-deficient murine hippocampal neurons responding to diffuse (PMA/ionomycin) stimulation. In contrast, neurons lacking spine-enriched NF-κB are selectively impaired in NF-κB-dependent gene expression induced by elevated excitatory synaptic stimulation (bicuculline or glycine). We used the setting of excitatory synaptic activity during development that produces NF-κB-dependent growth of dendritic spines to test physiological function of spine-enriched NF-κB in an activity-dependent response. Expression of wild-type p65, but not p65ΔSE, is capable of rescuing spine density to normal levels in p65-deficient pyramidal neurons. Collectively, these data reveal that spatial localization in dendritic spines contributes unique capacities to the NF-κB transcription factor in synaptic activity-dependent responses. SIGNIFICANCE STATEMENT Extensive research has established a model in which the regulation of neuronal gene expression enables enduring forms of plasticity and learning. However, mechanisms imparting stimulus specificity to gene regulation, ensuring biologically appropriate responses, remain incompletely understood. NF-κB is a potent transcription factor with evolutionarily conserved functions in learning and the growth of excitatory synaptic contacts. Neuronal NF-κB is localized in both synapse and

  7. Cell-specific gain modulation by synaptically released zinc in cortical circuits of audition.

    Science.gov (United States)

    Anderson, Charles T; Kumar, Manoj; Xiong, Shanshan; Tzounopoulos, Thanos

    2017-09-09

    In many excitatory synapses, mobile zinc is found within glutamatergic vesicles and is coreleased with glutamate. Ex vivo studies established that synaptically released (synaptic) zinc inhibits excitatory neurotransmission at lower frequencies of synaptic activity but enhances steady state synaptic responses during higher frequencies of activity. However, it remains unknown how synaptic zinc affects neuronal processing in vivo. Here, we imaged the sound-evoked neuronal activity of the primary auditory cortex in awake mice. We discovered that synaptic zinc enhanced the gain of sound-evoked responses in CaMKII-expressing principal neurons, but it reduced the gain of parvalbumin- and somatostatin-expressing interneurons. This modulation was sound intensity-dependent and, in part, NMDA receptor-independent. By establishing a previously unknown link between synaptic zinc and gain control of auditory cortical processing, our findings advance understanding about cortical synaptic mechanisms and create a new framework for approaching and interpreting the role of the auditory cortex in sound processing.

  8. Glia co-culture with neurons in microfluidic platforms promotes the formation and stabilization of synaptic contacts.

    Science.gov (United States)

    Shi, Mingjian; Majumdar, Devi; Gao, Yandong; Brewer, Bryson M; Goodwin, Cody R; McLean, John A; Li, Deyu; Webb, Donna J

    2013-08-07

    Two novel microfluidic cell culture schemes, a vertically-layered set-up and a four chamber set-up, were developed for co-culturing central nervous system (CNS) neurons and glia. The cell chambers in these devices were separated by pressure-enabled valve barriers, which permitted us to control communication between the two cell types. The unique design of these devices facilitated the co-culture of glia with neurons in close proximity (∼50-100 μm), differential transfection of neuronal populations, and dynamic visualization of neuronal interactions, such as the development of synapses. With these co-culture devices, initial synaptic contact between neurons transfected with different fluorescent markers, such as green fluorescent protein (GFP) and mCherry-synaptophysin, was imaged using high-resolution fluorescence microscopy. The presence of glial cells had a profound influence on synapses by increasing the number and stability of synaptic contacts. Interestingly, as determined by liquid chromatography-ion mobility-mass spectrometry, neuron-glia co-cultures produced elevated levels of soluble factors compared to that secreted by individual neuron or glia cultures, suggesting a potential mechanism by which neuron-glia interactions could modulate synaptic function. Collectively, these results show that communication between neurons and glia is critical for the formation and stability of synapses and point to the importance of developing neuron-glia co-culture systems such as the microfluidic platforms described in this study.

  9. A Ca2+-based computational model for NDMA receptor-dependent synaptic plasticity at individual post-synaptic spines in the hippocampus

    Directory of Open Access Journals (Sweden)

    Owen Rackham

    2010-07-01

    Full Text Available Associative synaptic plasticity is synapse specific and requires coincident activity in presynaptic and postsynaptic neurons to activate NMDA receptors (NMDARs. The resultant Ca2+ influx is the critical trigger for the induction of synaptic plasticity. Given its centrality for the induction of synaptic plasticity, a model for NMDAR activation incorporating the timing of presynaptic glutamate release and postsynaptic depolarization by back-propagating action potentials could potentially predict the pre- and post-synaptic spike patterns required to induce synaptic plasticity. We have developed such a model by incorporating currently available data on the timecourse and amplitude of the postsynaptic membrane potential within individual spines. We couple this with data on the kinetics of synaptic NMDARs and then use the model to predict the continuous spine [Ca2+] in response to regular or irregular pre- and post-synaptic spike patterns. We then incorporate experimental data from synaptic plasticity induction protocols by regular activity patterns to couple the predicted local peak [Ca2+] to changes in synaptic strength. We find that our model accurately describes [Ca2+] in dendritic spines resulting from NMDAR activation during presynaptic and postsynaptic activity when compared to previous experimental observations. The model also replicates the experimentally determined plasticity outcome of regular and irregular spike patterns when applied to a single synapse. This model could therefore be used to predict the induction of synaptic plasticity under a variety of experimental conditions and spike patterns.

  10. Visual recognition memory, manifested as long-term habituation, requires synaptic plasticity in V1.

    Science.gov (United States)

    Cooke, Sam F; Komorowski, Robert W; Kaplan, Eitan S; Gavornik, Jeffrey P; Bear, Mark F

    2015-02-01

    Familiarity with stimuli that bring neither reward nor punishment, manifested through behavioral habituation, enables organisms to detect novelty and devote cognition to important elements of the environment. Here we describe in mice a form of long-term behavioral habituation to visual grating stimuli that is selective for stimulus orientation. Orientation-selective habituation (OSH) can be observed both in exploratory behavior in an open arena and in a stereotyped motor response to visual stimuli in head-restrained mice. We found that the latter behavioral response, termed a 'vidget', requires V1. Parallel electrophysiological recordings in V1 revealed that plasticity, in the form of stimulus-selective response potentiation (SRP), occurred in layer 4 of V1 as OSH developed. Local manipulations of V1 that prevented and reversed electrophysiological modifications likewise prevented and reversed memory demonstrated behaviorally. These findings suggest that a form of long-term visual recognition memory is stored via synaptic plasticity in primary sensory cortex.

  11. Sleep and protein synthesis-dependent synaptic plasticity: impacts of sleep loss and stress

    Science.gov (United States)

    Grønli, Janne; Soulé, Jonathan; Bramham, Clive R.

    2014-01-01

    Sleep has been ascribed a critical role in cognitive functioning. Several lines of evidence implicate sleep in the consolidation of synaptic plasticity and long-term memory. Stress disrupts sleep while impairing synaptic plasticity and cognitive performance. Here, we discuss evidence linking sleep to mechanisms of protein synthesis-dependent synaptic plasticity and synaptic scaling. We then consider how disruption of sleep by acute and chronic stress may impair these mechanisms and degrade sleep function. PMID:24478645

  12. Polymer-electrolyte-gated nanowire synaptic transistors for neuromorphic applications

    Science.gov (United States)

    Zou, Can; Sun, Jia; Gou, Guangyang; Kong, Ling-An; Qian, Chuan; Dai, Guozhang; Yang, Junliang; Guo, Guang-hua

    2017-09-01

    Polymer-electrolytes are formed by dissolving a salt in polymer instead of water, the conducting mechanism involves the segmental motion-assisted diffusion of ion in the polymer matrix. Here, we report on the fabrication of tin oxide (SnO2) nanowire synaptic transistors using polymer-electrolyte gating. A thin layer of poly(ethylene oxide) and lithium perchlorate (PEO/LiClO4) was deposited on top of the devices, which was used to boost device performances. A voltage spike applied on the in-plane gate attracts ions toward the polymer-electrolyte/SnO2 nanowire interface and the ions are gradually returned after the pulse is removed, which can induce a dynamic excitatory postsynaptic current in the nanowire channel. The SnO2 synaptic transistors exhibit the behavior of short-term plasticity like the paired-pulse facilitation and self-adaptation, which is related to the electric double-effect regulation. In addition, the synaptic logic functions and the logical function transformation are also discussed. Such single SnO2 nanowire-based synaptic transistors are of great importance for future neuromorphic devices.

  13. The Predominance of Electric Transport in Synaptic Transmission

    OpenAIRE

    Hamid Reza Noori

    2008-01-01

    The quantitative description of the motion of neurotransmitters in the synaptic cleft appears to be one of the most difficult problems in the modeling of synapses. Here we show in contradiction to the common view, that this process is merely governed by electric transport than diffusion forces.

  14. Synaptically evoked glutamate transporter currents in Spinal Dorsal Horn Astrocytes

    Directory of Open Access Journals (Sweden)

    Dougherty Patrick M

    2009-07-01

    Full Text Available Abstract Background Removing and sequestering synaptically released glutamate from the extracellular space is carried out by specific plasma membrane transporters that are primarily located in astrocytes. Glial glutamate transporter function can be monitored by recording the currents that are produced by co-transportation of Na+ ions with the uptake of glutamate. The goal of this study was to characterize glutamate transporter function in astrocytes of the spinal cord dorsal horn in real time by recording synaptically evoked glutamate transporter currents. Results Whole-cell patch clamp recordings were obtained from astrocytes in the spinal substantia gelatinosa (SG area in spinal slices of young adult rats. Glutamate transporter currents were evoked in these cells by electrical stimulation at the spinal dorsal root entry zone in the presence of bicuculline, strychnine, DNQX and D-AP5. Transporter currents were abolished when synaptic transmission was blocked by TTX or Cd2+. Pharmacological studies identified two subtypes of glutamate transporters in spinal astrocytes, GLAST and GLT-1. Glutamate transporter currents were graded with stimulus intensity, reaching peak responses at 4 to 5 times activation threshold, but were reduced following low-frequency (0.1 – 1 Hz repetitive stimulation. Conclusion These results suggest that glutamate transporters of spinal astrocytes could be activated by synaptic activation, and recording glutamate transporter currents may provide a means of examining the real time physiological responses of glial cells in spinal sensory processing, sensitization, hyperalgesia and chronic pain.

  15. Inflammation subverts hippocampal synaptic plasticity in experimental multiple sclerosis.

    Directory of Open Access Journals (Sweden)

    Robert Nisticò

    Full Text Available Abnormal use-dependent synaptic plasticity is universally accepted as the main physiological correlate of memory deficits in neurodegenerative disorders. It is unclear whether synaptic plasticity deficits take place during neuroinflammatory diseases, such as multiple sclerosis (MS and its mouse model, experimental autoimmune encephalomyelitis (EAE. In EAE mice, we found significant alterations of synaptic plasticity rules in the hippocampus. When compared to control mice, in fact, hippocampal long-term potentiation (LTP induction was favored over long-term depression (LTD in EAE, as shown by a significant rightward shift in the frequency-synaptic response function. Notably, LTP induction was also enhanced in hippocampal slices from control mice following interleukin-1β (IL-1β perfusion, and both EAE and IL-1β inhibited GABAergic spontaneous inhibitory postsynaptic currents (sIPSC without affecting glutamatergic transmission and AMPA/NMDA ratio. EAE was also associated with selective loss of GABAergic interneurons and with reduced gamma-frequency oscillations in the CA1 region of the hippocampus. Finally, we provided evidence that microglial activation in the EAE hippocampus was associated with IL-1β expression, and hippocampal slices from control mice incubated with activated microglia displayed alterations of GABAergic transmission similar to those seen in EAE brains, through a mechanism dependent on enhanced IL-1β signaling. These data may yield novel insights into the basis of cognitive deficits in EAE and possibly of MS.

  16. Estrogen's Place in the Family of Synaptic Modulators.

    Science.gov (United States)

    Kramár, Enikö A; Chen, Lulu Y; Rex, Christopher S; Gall, Christine M; Lynch, Gary

    2009-01-01

    Estrogen, in addition to its genomic effects, triggers rapid synaptic changes in hippocampus and cortex. Here we summarize evidence that the acute actions of the steroid arise from actin signaling cascades centrally involved in long-term potentiation (LTP). A 10-min infusion of E2 reversibly increased fast EPSPs and promoted theta burst-induced LTP within adult hippocampal slices. The latter effect reflected a lowered threshold and an elevated ceiling for the potentiation effect. E2's actions on transmission and plasticity were completely blocked by latrunculin, a toxin that prevents actin polymerization. E2 also caused a reversible increase in spine concentrations of filamentous (F-) actin and markedly enhanced polymerization caused by theta burst stimulation (TBS). Estrogen activated the small GTPase RhoA, but not the related GTPase Rac, and phosphorylated (inactivated) synaptic cofilin, an actin severing protein targeted by RhoA. An inhibitor of RhoA kinase (ROCK) thoroughly suppressed the synaptic effects of E2. Collectively, these results indicate that E2 engages a RhoA >ROCK> cofilin> actin pathway also used by brain-derived neurotrophic factor and adenosine, and therefore belongs to a family of 'synaptic modulators' that regulate plasticity. Finally, we describe evidence that the acute signaling cascade is critical to the depression of LTP produced by ovariectomy.

  17. Inflammation Subverts Hippocampal Synaptic Plasticity in Experimental Multiple Sclerosis

    Science.gov (United States)

    Mandolesi, Georgia; Piccinin, Sonia; Berretta, Nicola; Pignatelli, Marco; Feligioni, Marco; Musella, Alessandra; Gentile, Antonietta; Mori, Francesco; Bernardi, Giorgio; Nicoletti, Ferdinando; Mercuri, Nicola B.; Centonze, Diego

    2013-01-01

    Abnormal use-dependent synaptic plasticity is universally accepted as the main physiological correlate of memory deficits in neurodegenerative disorders. It is unclear whether synaptic plasticity deficits take place during neuroinflammatory diseases, such as multiple sclerosis (MS) and its mouse model, experimental autoimmune encephalomyelitis (EAE). In EAE mice, we found significant alterations of synaptic plasticity rules in the hippocampus. When compared to control mice, in fact, hippocampal long-term potentiation (LTP) induction was favored over long-term depression (LTD) in EAE, as shown by a significant rightward shift in the frequency–synaptic response function. Notably, LTP induction was also enhanced in hippocampal slices from control mice following interleukin-1β (IL-1β) perfusion, and both EAE and IL-1β inhibited GABAergic spontaneous inhibitory postsynaptic currents (sIPSC) without affecting glutamatergic transmission and AMPA/NMDA ratio. EAE was also associated with selective loss of GABAergic interneurons and with reduced gamma-frequency oscillations in the CA1 region of the hippocampus. Finally, we provided evidence that microglial activation in the EAE hippocampus was associated with IL-1β expression, and hippocampal slices from control mice incubated with activated microglia displayed alterations of GABAergic transmission similar to those seen in EAE brains, through a mechanism dependent on enhanced IL-1β signaling. These data may yield novel insights into the basis of cognitive deficits in EAE and possibly of MS. PMID:23355887

  18. High bandwidth synaptic communication and frequency tracking in human neocortex

    NARCIS (Netherlands)

    Testa-Silva, Guilherme; Verhoog, Matthijs B; Linaro, Daniele; de Kock, Christiaan P J; Baayen, Johannes C; Meredith, Rhiannon M; De Zeeuw, Chris I; Giugliano, Michele; Mansvelder, Huibert D

    2014-01-01

    Neuronal firing, synaptic transmission, and its plasticity form the building blocks for processing and storage of information in the brain. It is unknown whether adult human synapses are more efficient in transferring information between neurons than rodent synapses. To test this, we recorded from

  19. High bandwidth synaptic communication and frequency tracking in human neocortex.

    NARCIS (Netherlands)

    Testa-Silva, G.; Verhoog, M.B.; Linaro, D.; de Kock, C.P.J.; Baayen, J.C.; Meredith, R.M.; Zeeuw, C.I.; Giugliano, M.; Mansvelder, H.D.

    2014-01-01

    Neuronal firing, synaptic transmission, and its plasticity form the building blocks for processing and storage of information in the brain. It is unknown whether adult human synapses are more efficient in transferring information between neurons than rodent synapses. To test this, we recorded from

  20. High Bandwidth Synaptic Communication and Frequency Tracking in Human Neocortex

    NARCIS (Netherlands)

    G. Testa-Silva (Guilherme); M.B. Verhoog (Matthijs); D. Linaro (Daniele); C.P.J. de Kock (Christiaan); J.C. Baayen; R.M. Meredith (Rhiannon); C.I. de Zeeuw (Chris); M. Giugliano (Michele); H.D. Mansvelder (Huibert)

    2014-01-01

    textabstractNeuronal firing, synaptic transmission, and its plasticity form the building blocks for processing and storage of information in the brain. It is unknown whether adult human synapses are more efficient in transferring information between neurons than rodent synapses. To test this, we

  1. Intense synaptic activity enhances temporal resolution in spinal motoneurons.

    Directory of Open Access Journals (Sweden)

    Rune W Berg

    Full Text Available In neurons, spike timing is determined by integration of synaptic potentials in delicate concert with intrinsic properties. Although the integration time is functionally crucial, it remains elusive during network activity. While mechanisms of rapid processing are well documented in sensory systems, agility in motor systems has received little attention. Here we analyze how intense synaptic activity affects integration time in spinal motoneurons during functional motor activity and report a 10-fold decrease. As a result, action potentials can only be predicted from the membrane potential within 10 ms of their occurrence and detected for less than 10 ms after their occurrence. Being shorter than the average inter-spike interval, the AHP has little effect on integration time and spike timing, which instead is entirely determined by fluctuations in membrane potential caused by the barrage of inhibitory and excitatory synaptic activity. By shortening the effective integration time, this intense synaptic input may serve to facilitate the generation of rapid changes in movements.

  2. Glutamatergic synaptic plasticity in the mesocorticolimbic system in addiction.

    NARCIS (Netherlands)

    van Huijstee, A.N.; Mansvelder, H.D.

    2015-01-01

    Addictive drugs remodel the brain’s reward circuitry, the mesocorticolimbic dopamine (DA) system, by inducing widespread adaptations of glutamatergic synapses. This drug-induced synaptic plasticity is thought to contribute to both the development and the persistence of addiction. This review

  3. Synaptic activity regulates AMPA receptor trafficking through different recycling pathways

    Science.gov (United States)

    Zheng, Ning; Jeyifous, Okunola; Munro, Charlotte; Montgomery, Johanna M; Green, William N

    2015-01-01

    Changes in glutamatergic synaptic strength in brain are dependent on AMPA-type glutamate receptor (AMPAR) recycling, which is assumed to occur through a single local pathway. In this study, we present evidence that AMPAR recycling occurs through different pathways regulated by synaptic activity. Without synaptic stimulation, most AMPARs recycled in dynamin-independent endosomes containing the GTPase, Arf6. Few AMPARs recycled in dynamin-dependent endosomes labeled by transferrin receptors (TfRs). AMPAR recycling was blocked by alterations in the GTPase, TC10, which co-localized with Arf6 endosomes. TC10 mutants that reduced AMPAR recycling had no effect on increased AMPAR levels with long-term potentiation (LTP) and little effect on decreased AMPAR levels with long-term depression. However, internalized AMPAR levels in TfR-containing recycling endosomes increased after LTP, indicating increased AMPAR recycling through the dynamin-dependent pathway with synaptic plasticity. LTP-induced AMPAR endocytosis is inconsistent with local recycling as a source of increased surface receptors, suggesting AMPARs are trafficked from other sites. DOI: http://dx.doi.org/10.7554/eLife.06878.001 PMID:25970033

  4. Inhibitory Synaptic Plasticity - Spike timing dependence and putative network function.

    Directory of Open Access Journals (Sweden)

    Tim P Vogels

    2013-07-01

    Full Text Available While the plasticity of excitatory synaptic connections in the brain has been widely studied, the plasticity of inhibitory connections is much less understood. Here, we present recent experimental and theoretical □ndings concerning the rules of spike timing-dependent inhibitory plasticity and their putative network function. This is a summary of a workshop at the COSYNE conference 2012.

  5. Irregular persistent activity induced by synaptic excitatory feedback

    Directory of Open Access Journals (Sweden)

    Francesca Barbieri

    2007-11-01

    Full Text Available Neurophysiological experiments on monkeys have reported highly irregular persistent activity during the performance of an oculomotor delayed-response task. These experiments show that during the delay period the coefficient of variation (CV of interspike intervals (ISI of prefrontal neurons is above 1, on average, and larger than during the fixation period. In the present paper, we show that this feature can be reproduced in a network in which persistent activity is induced by excitatory feedback, provided that (i the post-spike reset is close enough to threshold , (ii synaptic efficacies are a non-linear function of the pre-synaptic firing rate. Non-linearity between presynaptic rate and effective synaptic strength is implemented by a standard short-term depression mechanism (STD. First, we consider the simplest possible network with excitatory feedback: a fully connected homogeneous network of excitatory leaky integrate-and-fire neurons, using both numerical simulations and analytical techniques. The results are then confirmed in a network with selective excitatory neurons and inhibition. In both the cases there is a large range of values of the synaptic efficacies for which the statistics of firing of single cells is similar to experimental data.

  6. Impaired contextual fear extinction and hippocampal synaptic plasticity in adult rats induced by prenatal morphine exposure.

    Science.gov (United States)

    Tan, Ji-Wei; Duan, Ting-Ting; Zhou, Qi-Xin; Ding, Ze-Yang; Jing, Liang; Cao, Jun; Wang, Li-Ping; Mao, Rong-Rong; Xu, Lin

    2015-07-01

    Prenatal opiate exposure causes a series of neurobehavioral disturbances by affecting brain development. However, the question of whether prenatal opiate exposure increases vulnerability to memory-related neuropsychiatric disorders in adult offspring remains largely unknown. Here, we found that rats prenatally exposed to morphine (PM) showed impaired acquisition but enhanced maintenance of contextual fear memory compared with control animals that were prenatally exposed to saline (PS). The impairment of acquisition was rescued by increasing the intensity of footshocks (1.2 mA rather than 0.8 mA). Meanwhile, we also found that PM rats exhibited impaired extinction of contextual fear, which is associated with enhanced maintenance of fear memory. The impaired extinction lasted for 1 week following extinction training. Furthermore, PM rats exhibited reduced anxiety-like behavior in the elevated plus-maze and light/dark box test without differences in locomotor activity. These alterations in PM rats were mirrored by abnormalities in synaptic plasticity in the Schaffer collateral-CA1 synapses of the hippocampus in vivo. PS rats showed blocked long-term potentiation and enabled long-term depression in CA1 synapses following contextual fear conditioning, while prenatal morphine exposure restricted synaptic plasticity in CA1 synapses. The smaller long-term potentiation in PM rats was not further blocked by contextual fear conditioning, and the long-term depression enabled by contextual fear conditioning was abolished. Taken together, our results provide the first evidence suggesting that prenatal morphine exposure may increase vulnerability to fear memory-related neuropsychiatric disorders in adulthood. © 2014 Society for the Study of Addiction.

  7. In vivo assessment of [11C]MRB as a prospective PET ligand for imaging the norepinephrine transporter

    International Nuclear Information System (INIS)

    Severance, Alin J.; Milak, Matthew S.; Dileep Kumar, J.S.; Arango, Victoria; Parsey, Ramin V.; Prabhakaran, Jaya; Majo, Vattoly J.; Simpson, Norman R.; Van Heertum, Ronald L.; Mann, J.J.

    2007-01-01

    Antagonism of norepinephrine reuptake is now an important pharmacological strategy in the treatment of anxiety and depressive disorders, and many antidepressants have substantial potential occupancy of the norepinephrine transporter (NET) at recommended dosages. Despite the importance of understanding this transporter's role in psychiatric disease and treatment, a suitable radioligand for studying NET has been slow to emerge. (S,S)-Methylreboxetine (MRB) is among the more promising ligands recently adapted for positron emission tomography (PET), and the present study aimed to evaluate its potential for use in higher primates. Affinities for various brain targets were determined in vitro. PET studies were conducted in baboon under both test-retest and blocking conditions using 1 mg/kg nisoxetine. MRB has sixfold higher affinity for NET than the serotonin transporter, and negligible affinity for other sites. PET studies in baboons showed little regional heterogeneity in binding and were minimally affected by pretreatment with the NET antagonist nisoxetine. Despite improvement over previous ligands for imaging NET in vivo, the low signal to noise ratio indicates [ 11 C]MRB lacks sensitivity and reliability as a PET radiotracer in humans. (orig.)

  8. Hypersensitivity to norepinephrine in vasa deferentia from diabetic rats. Possible participation of metabolic products of arachidonic acid

    Energy Technology Data Exchange (ETDEWEB)

    Peredo, H; Agostini, M D; Gimeno, M F; Borda, E S

    1984-08-01

    Contractile responses to norepinephrine of the vas deferens isolated from normal and diabetic rats as well as tissue radio-conversion of exogenous arachidonic acid, were studied. Vasa deferentia from rats with acute streptozotocin-induced diabetes showed hypersensitivity to exogenous norepinephrine (NE). This increased contractile response was associated with the interaction of the agonist with alpha adrenoceptors. Inhibitors of cyclooxygenase increased and inhibitors of lipoxygenase(s) abolished the enhanced response to NE of diabetic vas deferens. Vasa deferentia from both normal and diabetic rats, converted (1-/sup 14/C)-arachidonic acid (AA) into PGF, PGE, PGD and thromboxane (TX) B2, but the % of AA metabolites formed was significantly higher in the diabetic than in the normal condition. Moreover, the predominant prostanoid generated by tissue preparations from diabetic animals was PGD2. Taken together the present experimental findings indicate that preparations from rats with acute streptozotocin-induced diabetes have an augmented reactivity towards NE, which appeared associated with changes in metabolites of AA generated via cyclooxygenase and lipoxygenase catalized pathways.

  9. Association between norepinephrine transporter gene (SLC6A2) polymorphisms and suicide in patients with major depressive disorder.

    Science.gov (United States)

    Kim, Yong-Ku; Hwang, Jung-A; Lee, Heon-Jeong; Yoon, Ho-Kyoung; Ko, Young-Hoon; Lee, Bun-Hee; Jung, Han-Yong; Hahn, Sang-Woo; Na, Kyoung-Sae

    2014-04-01

    Although several studies have investigated possible associations between norepinephrine neurotransmitter transporter gene (SLC6A2) polymorphisms and depression, few studies have examined associations between SLC6A2 polymorphisms and suicide. Three single-nucleotide polymorphisms (rs2242446, rs28386840, and rs5569) were measured in 550 patients: 201 with major depressive disorder (MDD) and suicide attempt/s, 160 with MDD without suicide attempts, and 189 healthy controls. Analysis of single-nucleotide polymorphisms (SNPs) and haplotype was conducted for the three groups. Subsequently, multivariate logistic regression analysis adjusting for age and gender was conducted to identify independent influences of each SNP. A possible association between suicide lethality and SLC6A2 polymorphisms was also investigated. In the genotype and allele frequency analysis, there were significant differences in rs28386840 between suicidal MDD patients and healthy controls. In the haplotype analysis, TAA (rs2242446-rs28386840-rs5569, from left to right) was associated with suicide attempts in MDD, although the significance (p=0.043) disappeared after Bonferroni correction. There were no relationships between lethality scores and SLC6A2 polymorphisms in suicidal MDD. Modest sample size and a single type of neurotransmitter analyzed (norepinephrine) are the primary limitations. Our results suggest that SLC6A2 polymorphisms were associated with suicide risk in patients with MDD. Future studies are warranted to elucidate possible mechanisms by which SLC6A2 polymorphisms influence suicide risk. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Effects of cocaine on [11C]norepinephrine and [11C]β-CIT uptake in the primate peripheral organs measured by PET

    International Nuclear Information System (INIS)

    Suhara, Tetsuya; Farde, L.; Halldin, C.; Karlsson, P.; Nagren, K.

    1996-01-01

    The toxic properties of cocaine are related to both the central and peripheral effects. To identify possible lethal mechanisms and the accumulation of cocaine in various organs, the effects of cocaine on [ 11 C] norepinephrine and cocaine congener [ 11 C]β-CIT uptake in Cynomolgus monkeys were measured by positron emission tomography (PET). Cocaine (5 mg/kg) noticeably inhibited [ 11 C] norepinephrine uptake in the heart. The uptake of [ 11 C]β-CIT in the heart and lung was reduced by pretreatment with cocaine. There was a significant uptake in the liver which was increased following cocaine pretreatment. The results of this study confirm that cocaine blocks the neuronal uptake of norepinephrine in sympathetic nerve terminals in the myocardium. The effect of cocaine on [ 11 C]β-CIT uptake indicates that the binding sites in the heart and lung are saturable, while the uptake mechanism in the liver is different from those of the heart and lung. (author)

  11. FOILFEST :community enabled security.

    Energy Technology Data Exchange (ETDEWEB)

    Moore, Judy Hennessey; Johnson, Curtis Martin; Whitley, John B.; Drayer, Darryl Donald; Cummings, John C., Jr. (.,; .)

    2005-09-01

    The Advanced Concepts Group of Sandia National Laboratories hosted a workshop, ''FOILFest: Community Enabled Security'', on July 18-21, 2005, in Albuquerque, NM. This was a far-reaching look into the future of physical protection consisting of a series of structured brainstorming sessions focused on preventing and foiling attacks on public places and soft targets such as airports, shopping malls, hotels, and public events. These facilities are difficult to protect using traditional security devices since they could easily be pushed out of business through the addition of arduous and expensive security measures. The idea behind this Fest was to explore how the public, which is vital to the function of these institutions, can be leveraged as part of a physical protection system. The workshop considered procedures, space design, and approaches for building community through technology. The workshop explored ways to make the ''good guys'' in public places feel safe and be vigilant while making potential perpetrators of harm feel exposed and convinced that they will not succeed. Participants in the Fest included operators of public places, social scientists, technology experts, representatives of government agencies including DHS and the intelligence community, writers and media experts. Many innovative ideas were explored during the fest with most of the time spent on airports, including consideration of the local airport, the Albuquerque Sunport. Some provocative ideas included: (1) sniffers installed in passage areas like revolving door, escalators, (2) a ''jumbotron'' showing current camera shots in the public space, (3) transparent portal screeners allowing viewing of the screening, (4) a layered open/funnel/open/funnel design where open spaces are used to encourage a sense of ''communitas'' and take advantage of citizen ''sensing'' and funnels are technological

  12. Optogenetic Examination of Prefrontal-Amygdala Synaptic Development.

    Science.gov (United States)

    Arruda-Carvalho, Maithe; Wu, Wan-Chen; Cummings, Kirstie A; Clem, Roger L

    2017-03-15

    A brain network comprising the medial prefrontal cortex (mPFC) and amygdala plays important roles in developmentally regulated cognitive and emotional processes. However, very little is known about the maturation of mPFC-amygdala circuitry. We conducted anatomical tracing of mPFC projections and optogenetic interrogation of their synaptic connections with neurons in the basolateral amygdala (BLA) at neonatal to adult developmental stages in mice. Results indicate that mPFC-BLA projections exhibit delayed emergence relative to other mPFC pathways and establish synaptic transmission with BLA excitatory and inhibitory neurons in late infancy, events that coincide with a massive increase in overall synaptic drive. During subsequent adolescence, mPFC-BLA circuits are further modified by excitatory synaptic strengthening as well as a transient surge in feedforward inhibition. The latter was correlated with increased spontaneous inhibitory currents in excitatory neurons, suggesting that mPFC-BLA circuit maturation culminates in a period of exuberant GABAergic transmission. These findings establish a time course for the onset and refinement of mPFC-BLA transmission and point to potential sensitive periods in the development of this critical network. SIGNIFICANCE STATEMENT Human mPFC-amygdala functional connectivity is developmentally regulated and figures prominently in numerous psychiatric disorders with a high incidence of adolescent onset. However, it remains unclear when synaptic connections between these structures emerge or how their properties change with age. Our work establishes developmental windows and cellular substrates for synapse maturation in this pathway involving both excitatory and inhibitory circuits. The engagement of these substrates by early life experience may support the ontogeny of fundamental behaviors but could also lead to inappropriate circuit refinement and psychopathology in adverse situations. Copyright © 2017 the authors 0270-6474/17/372976-10$15.00/0.

  13. Modulation of the release of norepinephrine by gamma-aminobutyric acid and morphine in the frontal cerebral cortex of the rat

    International Nuclear Information System (INIS)

    Peoples, R.W.

    1989-01-01

    Agents that enhance gamma-aminobutyric acid, or GABA, neurotransmission modulate certain effects of opioids, such as analgesia. Opioid analgesia is mediated in part by norepinephrine in the forebrain. In this study, the interactions between morphine and GABAergic agents on release of [ 3 H] norepinephrine from rat frontal cerebral cortical slices were examined. GABA, 5 x 10 -5 -10 -3 M, enhanced potassium stimulated [ 3 H] norepinephrine release and reversed the inhibitory effect of morphine in a noncompetitive manner. GABA did not enhance release of [ 3 H] norepinephrine stimulated by the calcium ionophore A23187. The effect of GABA was reduced by the GABA A receptor antagonists bicuculline methiodide or picrotoxin, and by the selective inhibitor of GABA uptake SKF 89976A, but was blocked completely only when bicuculline methiodide and SKF 89976A were used in combination. The GABA A agonist muscimol, 10 -4 M, mimicked the effect of GABA, but the GABA B agonist (±)baclofen, 10 -4 M, did not affect the release of [ 3 H] norepinephrine in the absence or the presence of morphine. Thus GABA appears to produce this effect by stimulating GABA uptake and GABA A , but not GABA B , receptors. In contrast to the results that would be predicted for an event involving GABA A receptors, however, the effect of GABA did not desensitize, and benzodiazepine agonists did not enhance the effect of GABA at any concentration tested between 10 -8 and 10 -4 M. Thus these receptors may constitute a subclass of GABA A receptors. These results support a role of GABA uptake and GABA A receptors in enhancing the release of norepinephrine and modulating its inhibition by opioids in the frontal cortex of the rat

  14. Modulation of the release of norepinephrine by gamma-aminobutyric acid and morphine in the frontal cerebral cortex of the rat

    Energy Technology Data Exchange (ETDEWEB)

    Peoples, R.W.

    1989-01-01

    Agents that enhance gamma-aminobutyric acid, or GABA, neurotransmission modulate certain effects of opioids, such as analgesia. Opioid analgesia is mediated in part by norepinephrine in the forebrain. In this study, the interactions between morphine and GABAergic agents on release of ({sup 3}H) norepinephrine from rat frontal cerebral cortical slices were examined. GABA, 5 {times} 10{sup {minus}5}-10{sup {minus}3} M, enhanced potassium stimulated ({sup 3}H) norepinephrine release and reversed the inhibitory effect of morphine in a noncompetitive manner. GABA did not enhance release of ({sup 3}H) norepinephrine stimulated by the calcium ionophore A23187. The effect of GABA was reduced by the GABA{sub A} receptor antagonists bicuculline methiodide or picrotoxin, and by the selective inhibitor of GABA uptake SKF 89976A, but was blocked completely only when bicuculline methiodide and SKF 89976A were used in combination. The GABA{sub A} agonist muscimol, 10{sup {minus}4} M, mimicked the effect of GABA, but the GABA{sub B} agonist ({plus minus})baclofen, 10{sup {minus}4} M, did not affect the release of ({sup 3}H) norepinephrine in the absence or the presence of morphine. Thus GABA appears to produce this effect by stimulating GABA uptake and GABA{sub A}, but not GABA{sub B}, receptors. In contrast to the results that would be predicted for an event involving GABA{sub A} receptors, however, the effect of GABA did not desensitize, and benzodiazepine agonists did not enhance the effect of GABA at any concentration tested between 10{sup {minus}8} and 10{sup {minus}4} M. Thus these receptors may constitute a subclass of GABA{sub A} receptors. These results support a role of GABA uptake and GABA{sub A} receptors in enhancing the release of norepinephrine and modulating its inhibition by opioids in the frontal cortex of the rat.

  15. A comparison of N-methyl-D-aspartate-evoked release of adenosine and [3H]norepinephrine from rat cortical slices

    International Nuclear Information System (INIS)

    Hoehn, K.; Craig, C.G.; White, T.D.

    1990-01-01

    Tetrodotoxin reduced N-methyl-D-aspartate (NMDA)-evoked release of adenosine by 35% but virtually abolished [3H]norepinephrine release. Although [3H]norepinephrine release from rat cortical slices evoked by 500 microM NMDA was abolished by 1.2 mM Mg++, which produces a voltage-sensitive, uncompetitive block of NMDA-channels, adenosine release was increased in the presence of Mg++. Partial depolarization with 12 mM K+ relieved the Mg++ block of 500 microM NMDA-evoked [3H]norepinephrine release but did not affect adenosine release, indicating that a Mg++ requirement for the adenosine release process per se cannot account for this discrepancy. NMDA was 33 times more potent in releasing adenosine than [3H]norepinephrine. At submaximal concentrations of NMDA (10 and 20 microM), adenosine release was augmented in Mg+(+)-free medium. Although a high concentration of the uncompetitive NMDA antagonist MK-801 [(+)-5-methyl-10,11,dihydro-5H-dibenzo[a,d]cyclohepten-5-10-imine maleate] (3 microM) blocked NMDA-evoked release of [3H]norepinephrine and adenosine, a lower concentration (300 nM) decreased NMDA-evoked [3H]norepinephrine release by 66% without affecting adenosine release. These findings suggest that maximal adenosine release occurs when relatively few NMDA receptors are activated, raising the possibility that spare receptors exist for NMDA-evoked adenosine release. Rather than acting as a protectant against excessive NMDA excitation, released adenosine might provide an inhibitory threshold which must be overcome for NMDA-mediated neurotransmission to proceed

  16. Dietary supplement increases plasma norepinephrine, lipolysis, and metabolic rate in resistance trained men

    Directory of Open Access Journals (Sweden)

    Schilling Brian K

    2009-01-01

    Full Text Available Abstract Background Dietary supplements targeting fat loss and increased thermogenesis are prevalent within the sport nutrition/weight loss market. While some isolated ingredients have been reported to be efficacious when used at high dosages, in particular in animal models and/or via intravenous delivery, little objective evidence is available pertaining to the efficacy of a finished product taken by human subjects in oral form. Moreover, many ingredients function as stimulants, leading to increased hemodynamic responses. The purpose of this investigation was to determine the effects of a finished dietary supplement on plasma catecholamine concentration, markers of lipolysis, metabolic rate, and hemodynamics. Methods Ten resistance trained men (age = 27 ± 4 yrs; BMI = 25 ± 3 kg· m-2; body fat = 9 ± 3%; mean ± SD ingested a dietary supplement (Meltdown®, Vital Pharmaceuticals or a placebo, in a random order, double blind cross-over design, with one week separating conditions. Fasting blood samples were collected before, and at 30, 60, and 90 minutes post ingestion and were assayed for epinephrine (EPI, norepinephrine (NE, glycerol, and free fatty acids (FFA. Area under the curve (AUC was calculated for all variables. Gas samples were collected from 30–60 minutes post ingestion for measurement of metabolic rate. Heart rate and blood pressure were recorded at all blood collection times. Results AUC was greater for the dietary supplement compared to the placebo for NE (1332 ± 128 pg·mL-1·90 min-1 vs. 1003 ± 133 pg·mL-1·90 min-1; p = 0.03, glycerol (44 ± 3 μg·mL-1·90 min-1 vs. 26 ± 2 μg·mL-1·90 min-1; p -1·90 min-1 vs. 0.88 ± 0.12 mmol·L-1·90 min-1; p = 0.0003. No difference between conditions was noted for EPI AUC (p > 0.05. For all variables, values were highest at 90 minutes post ingestion. Total kilocalorie expenditure during the 30 minute collection period was 29.6% greater (p = 0.02 for the dietary supplement (35 ± 3

  17. Evidence for altered brain reactivity to norepinephrine in Veterans with a history of traumatic stress

    Directory of Open Access Journals (Sweden)

    Rebecca C. Hendrickson

    2018-02-01

    Full Text Available Background: Increases in the quantity or impact of noradrenergic signaling have been implicated in the pathophysiology of posttraumatic stress disorder (PTSD. This increased signaling may result from increased norepinephrine (NE release, from altered brain responses to NE, or from a combination of both factors. Here, we tested the hypothesis that Veterans reporting a history of trauma exposure would show an increased association between brain NE and mental health symptoms commonly observed after trauma, as compared to Veterans who did not report a history of trauma exposure, consistent with the possibility of increased brain reactivity to NE after traumatic stress. Methods: Using a convenience sample of 69 male Veterans with a history of combat-theater deployment, we examined the relationship between trauma-related mental health symptoms and the concentration of NE in cerebrospinal fluid (CSF. CSF NE levels were measured by HPLC in CSF from morning lumbar puncture. Behavioral symptoms associated with diagnoses of PTSD, depression, insomnia, or post-concussive syndrome (PCS, which together cover a wide variety of symptoms associated with alterations in arousal systems, such as sleep, mood, concentration, and anxiety, were assessed via self-report (PTSD Checklist [PCL] for PTSD, Patient Health Questionnaire 9 [PHQ9] for depression, Pittsburgh Sleep Quality Index [PSQI] for sleep problems including insomnia, and Neurobehavioral Symptom Inventory [NSI] for PCS and structured clinical interview (Clinician-Administered PSTD Scale [CAPS]. Individuals meeting criterion A of the DSM-IV diagnostic criteria for PTSD were considered trauma-exposed. Linear regression models were used to quantify the association between CSF NE and symptom intensity in participants with and without a history of trauma exposure, as well as in participants with a history of trauma exposure who were currently taking the noradrenergic receptor antagonist prazosin. Results: Fifty

  18. Odor-Specific Habituation Arises from Interaction of Afferent Synaptic Adaptation and Intrinsic Synaptic Potentiation in Olfactory Cortex

    Science.gov (United States)

    Linster, Christiane; Menon, Alka V.; Singh, Christopher Y.; Wilson, Donald A.

    2009-01-01

    Segmentation of target odorants from background odorants is a fundamental computational requirement for the olfactory system and is thought to be behaviorally mediated by olfactory habituation memory. Data from our laboratory have shown that odor-specific adaptation in piriform neurons, mediated at least partially by synaptic adaptation between…

  19. Statistical theory of synaptic connectivity in the neocortex

    Science.gov (United States)

    Escobar, Gina

    Learning and long-term memory rely on plasticity of neural circuits. In adult cerebral cortex plasticity can be mediated by modulation of existing synapses and structural reorganization of circuits through growth and retraction of dendritic spines. In the first part of this thesis, we describe a theoretical framework for the analysis of spine remodeling plasticity. New synaptic contacts appear in the neuropil where gaps between axonal and dendritic branches can be bridged by dendritic spines. Such sites are termed potential synapses. We derive expressions for the densities of potential synapses in the neuropil. We calculate the ratio of actual to potential synapses, called the connectivity fraction, and use it to find the number of structurally different circuits attainable with spine remodeling. These parameters are calculated in four systems: mouse occipital cortex, rat hippocampal area CA1, monkey primary visual (V1), and human temporal cortex. The neurogeometric results indicate that a dendritic spine can choose among an average of 4-7 potential targets in rodents, while in primates it can choose from 10-20 potential targets. The potential of the neuropil to undergo circuit remodeling is found to be highest in rat CA1 (4.9-6.0 nats/mum 3) and lowest in monkey V1 (0.9-1.0 nats/mum3). We evaluate the lower bound of neuron selectivity in the choice of synaptic partners and find that post-synaptic excitatory neurons in rodents make synaptic contacts with more than 21-30% of pre-synaptic axons encountered with new spine growth. Primate neurons appear to be more selective, making synaptic connections with more than 7-15% of encountered axons. Another plasticity mechanism is included in the second part of this work: long-term potentiation and depression of excitatory synaptic connections. Because synaptic strength is correlated with the size of the synapse, the former can be inferred from the distribution of spine head volumes. To this end we analyze and compare 166

  20. Agrin and synaptic laminin are required to maintain adult neuromuscular junctions.

    Directory of Open Access Journals (Sweden)

    Melanie A Samuel

    Full Text Available As synapses form and mature the synaptic partners produce organizing molecules that regulate each other's differentiation and ensure precise apposition of pre- and post-synaptic specializations. At the skeletal neuromuscular junction (NMJ, these molecules include agrin, a nerve-derived organizer of postsynaptic differentiation, and synaptic laminins, muscle-derived organizers of presynaptic differentiation. Both become concentrated in the synaptic cleft as the NMJ develops and are retained in adulthood. Here, we used mutant mice to ask whether these organizers are also required for synaptic maintenance. Deletion of agrin from a subset of adult motor neurons resulted in the loss of acetylcholine receptors and other components of the postsynaptic apparatus and synaptic cleft. Nerve terminals also atrophied and eventually withdrew from muscle fibers. On the other hand, mice lacking the presynaptic organizer laminin-α4 retained most of the synaptic cleft components but exhibited synaptic alterations reminiscent of those observed in aged animals. Although we detected no marked decrease in laminin or agrin levels at aged NMJs, we observed alterations in the distribution and organization of these synaptic cleft components suggesting that such changes could contribute to age-related synaptic disassembly. Together, these results demonstrate that pre- and post-synaptic organizers actively function to maintain the structure and function of adult NMJs.

  1. Preparation of synaptic plasma membrane and postsynaptic density proteins using a discontinuous sucrose gradient.

    Science.gov (United States)

    Bermejo, Marie Kristel; Milenkovic, Marija; Salahpour, Ali; Ramsey, Amy J

    2014-09-03

    Neuronal subcellular fractionation techniques allow the quantification of proteins that are trafficked to and from the synapse. As originally described in the late 1960's, proteins associated with the synaptic plasma membrane can be isolated by ultracentrifugation on a sucrose density gradient. Once synaptic membranes are isolated, the macromolecular complex known as the post-synaptic density can be subsequently isolated due to its detergent insolubility. The techniques used to isolate synaptic plasma membranes and post-synaptic density proteins remain essentially the same after 40 years, and are widely used in current neuroscience research. This article details the fractionation of proteins associated with the synaptic plasma membrane and post-synaptic density using a discontinuous sucrose gradient. Resulting protein preparations are suitable for western blotting or 2D DIGE analysis.

  2. Two Classes of Secreted Synaptic Organizers in the Central Nervous System.

    Science.gov (United States)

    Yuzaki, Michisuke

    2018-02-10

    Research in the last two decades has identified many synaptic organizers in the central nervous system that directly regulate the assembly of pre- and/or postsynaptic molecules, such as synaptic vesicles, active zone proteins, and neurotransmitter receptors. They are classified into secreted factors and cell adhesion molecules, such as neurexins and neuroligins. Certain secreted factors are termed extracellular scaffolding proteins (ESPs) because they are components of the synaptic extracellular matrix and serve as a scaffold at the synaptic cleft. These include Lgi1, Cbln1, neuronal pentraxins, Hevin, thrombospondins, and glypicans. Diffusible secreted factors, such as Wnts, fibroblast growth factors, and semaphorins, tend to act from a distance. In contrast, ESPs remain at the synaptic cleft and often help synaptic adhesion and/or accumulation of postsynaptic receptors. Many fundamental questions remain about when, how, and why various synaptic organizers establish and modify the vast numbers of connections during development and throughout life.

  3. Does autophagy work in synaptic plasticity and memory?

    Science.gov (United States)

    Shehata, Mohammad; Inokuchi, Kaoru

    2014-01-01

    Many studies have reported the roles played by regulated proteolysis in neural plasticity and memory. Within this context, most of the research focused on the ubiquitin-proteasome system and the endosome-lysosome system while giving lesser consideration to another major protein degradation system, namely, autophagy. Although autophagy intersects with many of the pathways known to underlie synaptic plasticity and memory, only few reports related autophagy to synaptic remodeling. These pathways include PI3K-mTOR pathway and endosome-dependent proteolysis. In this review, we will discuss several lines of evidence supporting a physiological role of autophagy in memory processes, and the possible mechanistic scenarios for how autophagy could fulfill this function.

  4. Synaptic Bistability Due to Nucleation and Evaporation of Receptor Clusters

    KAUST Repository

    Burlakov, V. M.

    2012-01-10

    We introduce a bistability mechanism for long-term synaptic plasticity based on switching between two metastable states that contain significantly different numbers of synaptic receptors. One state is characterized by a two-dimensional gas of mobile interacting receptors and is stabilized against clustering by a high nucleation barrier. The other state contains a receptor gas in equilibrium with a large cluster of immobile receptors, which is stabilized by the turnover rate of receptors into and out of the synapse. Transitions between the two states can be initiated by either an increase (potentiation) or a decrease (depotentiation) of the net receptor flux into the synapse. This changes the saturation level of the receptor gas and triggers nucleation or evaporation of receptor clusters. © 2012 American Physical Society.

  5. Emulating short-term synaptic dynamics with memristive devices

    Science.gov (United States)

    Berdan, Radu; Vasilaki, Eleni; Khiat, Ali; Indiveri, Giacomo; Serb, Alexandru; Prodromakis, Themistoklis

    2016-01-01

    Neuromorphic architectures offer great promise for achieving computation capacities beyond conventional Von Neumann machines. The essential elements for achieving this vision are highly scalable synaptic mimics that do not undermine biological fidelity. Here we demonstrate that single solid-state TiO2 memristors can exhibit non-associative plasticity phenomena observed in biological synapses, supported by their metastable memory state transition properties. We show that, contrary to conventional uses of solid-state memory, the existence of rate-limiting volatility is a key feature for capturing short-term synaptic dynamics. We also show how the temporal dynamics of our prototypes can be exploited to implement spatio-temporal computation, demonstrating the memristors full potential for building biophysically realistic neural processing systems.

  6. Short-term synaptic plasticity and heterogeneity in neural systems

    Science.gov (United States)

    Mejias, J. F.; Kappen, H. J.; Longtin, A.; Torres, J. J.

    2013-01-01

    We review some recent results on neural dynamics and information processing which arise when considering several biophysical factors of interest, in particular, short-term synaptic plasticity and neural heterogeneity. The inclusion of short-term synaptic plasticity leads to enhanced long-term memory capacities, a higher robustness of memory to noise, and irregularity in the duration of the so-called up cortical states. On the other hand, considering some level of neural heterogeneity in neuron models allows neural systems to optimize information transmission in rate coding and temporal coding, two strategies commonly used by neurons to codify information in many brain areas. In all these studies, analytical approximations can be made to explain the underlying dynamics of these neural systems.

  7. Random synaptic feedback weights support error backpropagation for deep learning

    Science.gov (United States)

    Lillicrap, Timothy P.; Cownden, Daniel; Tweed, Douglas B.; Akerman, Colin J.

    2016-01-01

    The brain processes information through multiple layers of neurons. This deep architecture is representationally powerful, but complicates learning because it is difficult to identify the responsible neurons when a mistake is made. In machine learning, the backpropagation algorithm assigns blame by multiplying error signals with all the synaptic weights on each neuron's axon and further downstream. However, this involves a precise, symmetric backward connectivity pattern, which is thought to be impossible in the brain. Here we demonstrate that this strong architectural constraint is not required for effective error propagation. We present a surprisingly simple mechanism that assigns blame by multiplying errors by even random synaptic weights. This mechanism can transmit teaching signals across multiple layers of neurons and performs as effectively as backpropagation on a variety of tasks. Our results help reopen questions about how the brain could use error signals and dispel long-held assumptions about algorithmic constraints on learning. PMID:27824044

  8. Irregular activity arises as a natural consequence of synaptic inhibition

    International Nuclear Information System (INIS)

    Terman, D.; Rubin, J. E.; Diekman, C. O.

    2013-01-01

    Irregular neuronal activity is observed in a variety of brain regions and states. This work illustrates a novel mechanism by which irregular activity naturally emerges in two-cell neuronal networks featuring coupling by synaptic inhibition. We introduce a one-dimensional map that captures the irregular activity occurring in our simulations of conductance-based differential equations and mathematically analyze the instability of fixed points corresponding to synchronous and antiphase spiking for this map. We find that the irregular solutions that arise exhibit expansion, contraction, and folding in phase space, as expected in chaotic dynamics. Our analysis shows that these features are produced from the interplay of synaptic inhibition with sodium, potassium, and leak currents in a conductance-based framework and provides precise conditions on parameters that ensure that irregular activity will occur. In particular, the temporal details of spiking dynamics must be present for a model to exhibit this irregularity mechanism and must be considered analytically to capture these effects

  9. Irregular activity arises as a natural consequence of synaptic inhibition

    Energy Technology Data Exchange (ETDEWEB)

    Terman, D., E-mail: terman@math.ohio-state.edu [Department of Mathematics, The Ohio State University, Columbus, Ohio 43210 (United States); Rubin, J. E., E-mail: jonrubin@pitt.edu [Department of Mathematics, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 (United States); Diekman, C. O., E-mail: diekman@njit.edu [Department of Mathematical Sciences, New Jersey Institute of Technology, Newark, New Jersey 07102 (United States)

    2013-12-15

    Irregular neuronal activity is observed in a variety of brain regions and states. This work illustrates a novel mechanism by which irregular activity naturally emerges in two-cell neuronal networks featuring coupling by synaptic inhibition. We introduce a one-dimensional map that captures the irregular activity occurring in our simulations of conductance-based differential equations and mathematically analyze the instability of fixed points corresponding to synchronous and antiphase spiking for this map. We find that the irregular solutions that arise exhibit expansion, contraction, and folding in phase space, as expected in chaotic dynamics. Our analysis shows that these features are produced from the interplay of synaptic inhibition with sodium, potassium, and leak currents in a conductance-based framework and provides precise conditions on parameters that ensure that irregular activity will occur. In particular, the temporal details of spiking dynamics must be present for a model to exhibit this irregularity mechanism and must be considered analytically to capture these effects.

  10. Inhibition of hippocampal synaptic transmission by impairment of Ral function

    DEFF Research Database (Denmark)

    Owe-Larsson, Björn; Chaves-Olarte, Esteban; Chauhan, Ashok

    2005-01-01

    Large clostridial cytotoxins and protein overexpression were used to probe for involvement of Ras-related GTPases (guanosine triphosphate) in synaptic transmission in cultured rat hippocampal neurons. The toxins TcdA-10463 (inactivates Rho, Rac, Cdc42, Rap) and TcsL-1522 (inactivates Ral, Rac, Ras......, R-Ras, Rap) both inhibited autaptic responses. In a proportion of the neurons (25%, TcdA-10463; 54%, TcsL-1522), the inhibition was associated with a shift from activity-dependent depression to facilitation, indicating that the synaptic release probability was reduced. Overexpression of a dominant...... negative Ral mutant, Ral A28N, caused a strong inhibition of autaptic responses, which was associated with a shift to facilitation in a majority (80%) of the neurons. These results indicate that Ral, along with at least one other non-Rab GTPase, participates in presynaptic regulation in hippocampal neurons....

  11. Stochastic learning in oxide binary synaptic device for neuromorphic computing.

    Science.gov (United States)

    Yu, Shimeng; Gao, Bin; Fang, Zheng; Yu, Hongyu; Kang, Jinfeng; Wong, H-S Philip

    2013-01-01

    Hardware implementation of neuromorphic computing is attractive as a computing paradigm beyond the conventional digital computing. In this work, we show that the SET (off-to-on) transition of metal oxide resistive switching memory becomes probabilistic under a weak programming condition. The switching variability of the binary synaptic device implements a stochastic learning rule. Such stochastic SET transition was statistically measured and modeled for a simulation of a winner-take-all network for competitive learning. The simulation illustrates that with such stochastic learning, the orientation classification function of input patterns can be effectively realized. The system performance metrics were compared between the conventional approach using the analog synapse and the approach in this work that employs the binary synapse utilizing the stochastic learning. The feasibility of using binary synapse in the neurormorphic computing may relax the constraints to engineer continuous multilevel intermediate states and widens the material choice for the synaptic device design.

  12. Fragile X Mental Retardation Protein Regulates Activity-Dependent Membrane Trafficking and Trans-Synaptic Signaling Mediating Synaptic Remodeling

    Science.gov (United States)

    Sears, James C.; Broadie, Kendal

    2018-01-01

    Fragile X syndrome (FXS) is the leading monogenic cause of autism and intellectual disability. The disease arises through loss of fragile X mental retardation protein (FMRP), which normally exhibits peak expression levels in early-use critical periods, and is required for activity-dependent synaptic remodeling during this transient developmental window. FMRP canonically binds mRNA to repress protein translation, with targets that regulate cytoskeleton dynamics, membrane trafficking, and trans-synaptic signaling. We focus here on recent advances emerging in these three areas from the Drosophila disease model. In the well-characterized central brain mushroom body (MB) olfactory learning/memory circuit, FMRP is required for activity-dependent synaptic remodeling of projection neurons innervating the MB calyx, with function tightly restricted to an early-use critical period. FMRP loss is phenocopied by conditional removal of FMRP only during this critical period, and rescued by FMRP conditional expression only during this critical period. Consistent with FXS hyperexcitation, FMRP loss defects are phenocopied by heightened sensory experience and targeted optogenetic hyperexcitation during this critical period. FMRP binds mRNA encoding Drosophila ESCRTIII core component Shrub (human CHMP4 homolog) to restrict Shrub translation in an activity-dependent mechanism only during this same critical period. Shrub mediates endosomal membrane trafficking, and perturbing Shrub expression is known to interfere with neuronal process pruning. Consistently, FMRP loss and Shrub overexpression targeted to projection neurons similarly causes endosomal membrane trafficking defects within synaptic boutons, and genetic reduction of Shrub strikingly rescues Drosophila FXS model defects. In parallel work on the well-characterized giant fiber (GF) circuit, FMRP limits iontophoretic dye loading into central interneurons, demonstrating an FMRP role controlling core neuronal properties through the

  13. Activity-dependent modulation of neural circuit synaptic connectivity

    Directory of Open Access Journals (Sweden)

    Charles R Tessier

    2009-07-01

    Full Text Available In many nervous systems, the establishment of neural circuits is known to proceed via a two-stage process; 1 early, activity-independent wiring to produce a rough map characterized by excessive synaptic connections, and 2 subsequent, use-dependent pruning to eliminate inappropriate connections and reinforce maintained synapses. In invertebrates, however, evidence of the activity-dependent phase of synaptic refinement has been elusive, and the dogma has long been that invertebrate circuits are “hard-wired” in a purely activity-independent manner. This conclusion has been challenged recently through the use of new transgenic tools employed in the powerful Drosophila system, which have allowed unprecedented temporal control and single neuron imaging resolution. These recent studies reveal that activity-dependent mechanisms are indeed required to refine circuit maps in Drosophila during precise, restricted windows of late-phase development. Such mechanisms of circuit refinement may be key to understanding a number of human neurological diseases, including developmental disorders such as Fragile X syndrome (FXS and autism, which are hypothesized to result from defects in synaptic connectivity and activity-dependent circuit function. This review focuses on our current understanding of activity-dependent synaptic connectivity in Drosophila, primarily through analyzing the role of the fragile X mental retardation protein (FMRP in the Drosophila FXS disease model. The particular emphasis of this review is on the expanding array of new genetically-encoded tools that are allowing cellular events and molecular players to be dissected with ever greater precision and detail.

  14. Convergent synaptic and circuit substrates underlying autism genetic risks.

    Science.gov (United States)

    McGee, Aaron; Li, Guohui; Lu, Zhongming; Qiu, Shenfeng

    2014-02-01

    There has been a surge of diagnosis of autism spectrum disorders (ASD) over the past decade. While large, high powered genome screening studies of children with ASD have identified numerous genetic risk factors, research efforts to understanding how each of these risk factors contributes to the development autism has met with limited success. Revealing the mechanisms by which these genetic risk factors affect brain development and predispose a child to autism requires mechanistic understanding of the neurobiological changes underlying this devastating group of developmental disorders at multifaceted molecular, cellular and system levels. It has been increasingly clear that the normal trajectory of neurodevelopment is compromised in autism, in multiple domains as much as aberrant neuronal production, growth, functional maturation, patterned connectivity, and balanced excitation and inhibition of brain networks. Many autism risk factors identified in humans have been now reconstituted in experimental mouse models to allow mechanistic interrogation of the biological role of the risk gene. Studies utilizing these mouse models have revealed that underlying the enormous heterogeneity of perturbed cellular events, mechanisms directing synaptic and circuit assembly may provide a unifying explanation for the pathophysiological changes and behavioral endophenotypes seen in autism, although synaptic perturbations are far from being the only alterations relevant for ASD. In this review, we discuss synaptic and circuit abnormalities obtained from several prevalent mouse models, particularly those reflecting syndromic forms of ASD that are caused by single gene perturbations. These compiled results reveal that ASD risk genes contribute to proper signaling of the developing gene networks that maintain synaptic and circuit homeostasis, which is fundamental to normal brain development.

  15. Quercetin targets cysteine string protein (CSPalpha and impairs synaptic transmission.

    Directory of Open Access Journals (Sweden)

    Fenglian Xu

    2010-06-01

    Full Text Available Cysteine string protein (CSPalpha is a synaptic vesicle protein that displays unique anti-neurodegenerative properties. CSPalpha is a member of the conserved J protein family, also called the Hsp40 (heat shock protein of 40 kDa protein family, whose importance in protein folding has been recognized for many years. Deletion of the CSPalpha in mice results in knockout mice that are normal for the first 2-3 weeks of life followed by an unexplained presynaptic neurodegeneration and premature death. How CSPalpha prevents neurodegeneration is currently not known. As a neuroprotective synaptic vesicle protein, CSPalpha represents a promising therapeutic target for the prevention of neurodegenerative disorders.Here, we demonstrate that the flavonoid quercetin promotes formation of stable CSPalpha-CSPalpha dimers and that quercetin-induced dimerization is dependent on the unique cysteine string region. Furthermore, in primary cultures of Lymnaea neurons, quercetin induction of CSPalpha dimers correlates with an inhibition of synapse formation and synaptic transmission suggesting that quercetin interfers with CSPalpha function. Quercetin's action on CSPalpha is concentration dependent and does not promote dimerization of other synaptic proteins or other J protein family members and reduces the assembly of CSPalpha:Hsc70 units (70kDa heat shock cognate protein.Quercetin is a plant derived flavonoid and popular nutritional supplement proposed to prevent memory loss and altitude sickness among other ailments, although its precise mechanism(s of action has been unclear. In view of the therapeutic promise of upregulation of CSPalpha and the undesired consequences of CSPalpha dysfunction, our data establish an essential proof of principle that pharmaceutical agents can selectively target the neuroprotective J protein CSPalpha.

  16. Presynaptic Active Zone Density during Development and Synaptic Plasticity.

    Science.gov (United States)

    Clarke, Gwenaëlle L; Chen, Jie; Nishimune, Hiroshi

    2012-01-01

    Neural circuits transmit information through synapses, and the efficiency of synaptic transmission is closely related to the density of presynaptic active zones, where synaptic vesicles are released. The goal of this review is to highlight recent insights into the molecular mechanisms that control the number of active zones per presynaptic terminal (active zone density) during developmental and stimulus-dependent changes in synaptic efficacy. At the neuromuscular junctions (NMJs), the active zone density is preserved across species, remains constant during development, and is the same between synapses with different activities. However, the NMJ active zones are not always stable, as exemplified by the change in active zone density during acute experimental manipulation or as a result of aging. Therefore, a mechanism must exist to maintain its density. In the central nervous system (CNS), active zones have restricted maximal size, exist in multiple numbers in larger presynaptic terminals, and maintain a constant density during development. These findings suggest that active zone density in the CNS is also controlled. However, in contrast to the NMJ, active zone density in the CNS can also be increased, as observed in hippocampal synapses in response to synaptic plasticity. Although the numbers of known active zone proteins and protein interactions have increased, less is known about the mechanism that controls the number or spacing of active zones. The following molecules are known to control active zone density and will be discussed herein: extracellular matrix laminins and voltage-dependent calcium channels, amyloid precursor proteins, the small GTPase Rab3, an endocytosis mechanism including synaptojanin, cytoskeleton protein spectrins and β-adducin, and a presynaptic web including spectrins. The molecular mechanisms that organize the active zone density are just beginning to be elucidated.

  17. Mechanisms of Synaptic Alterations in a Neuroinflammation Model of Autism

    Science.gov (United States)

    2015-10-01

    inhibitory presynaptic input in the cortex of MIA offspring To determine if the altered number, shape and dynamic proper- ties of spines are...affects synaptic function in the cortex . We performed whole-cell voltage -clamp recordings from layer 2 pyramidal neurons in the somatosensory cortex ...highly dynamic struc- tures with new spines forming and others disappearing on a time scale of minutes (Dailey and Smith, 1996; Dunaevsky et al., 1999

  18. Dynamic learning and memory, synaptic plasticity and neurogenesis: an update

    Czech Academy of Sciences Publication Activity Database

    Stuchlík, Aleš

    2014-01-01

    Roč. 8, APR 1 (2014), s. 106 ISSN 1662-5153 R&D Projects: GA ČR(CZ) GA14-03627S Grant - others:Rada Programu interní podpory projektů mezinárodní spolupráce AV ČR(CZ) M200111204 Institutional support: RVO:67985823 Keywords : learning * memory * synaptic plasticity * neurogenesis Subject RIV: FH - Neurology Impact factor: 3.270, year: 2014

  19. Robust Short-Term Memory without Synaptic Learning

    OpenAIRE

    Johnson, Samuel; Marro, J.; Torres, Joaquin J.

    2013-01-01

    Short-term memory in the brain cannot in general be explained the way long-term memory can ??? as a gradual modification of synaptic weights ??? since it takes place too quickly. Theories based on some form of cellular bistability, however, do not seem able to account for the fact that noisy neurons can collectively store information in a robust manner. We show how a sufficiently clustered network of simple model neurons can be instantly induced into metastable states capable of retaining inf...

  20. Synaptic metaplasticity underlies tetanic potentiation in Lymnaea: a novel paradigm.

    Directory of Open Access Journals (Sweden)

    Anita Mehta

    Full Text Available We present a mathematical model that explains and interprets a novel form of short-term potentiation, which was found to be use-, but not time-dependent, in experiments done on Lymnaea neurons. The high degree of potentiation is explained using a model of synaptic metaplasticity, while the use-dependence (which is critically reliant on the presence of kinase in the experiment is explained using a model of a stochastic and bistable biological switch.

  1. Two Aspects of ASIC Function: Synaptic Plasticity and Neuronal Injury.

    Science.gov (United States)

    Huang, Yan; Jiang, Nan; Li, Jun; Ji, Yong-Hua; Xiong, Zhi-Gang; Zha, Xiang-ming

    2015-01-01

    Extracellular brain pH fluctuates in both physiological and disease conditions. The main postsynaptic proton receptor is the acid-sensing ion channels (ASICs). During the past decade, much progress has been made on protons, ASICs, and neurological disease. This review summarizes the recent progress on synaptic role of protons and our current understanding of how ASICs contribute to various types of neuronal injury in the brain. PMID:25582290

  2. Cocaine inhibits extraneuronal O-methylation of exogenous norepinephrine in nasal and oral tissues of the rabbit

    International Nuclear Information System (INIS)

    de la Lande, I.S.; Parker, D.A.S.; Proctor, C.H.; Marino, V.; Mackay-Sim, A.

    1987-01-01

    Nasal mucosa (respirator and olfactory) and lingual gingiva of the rabbit were depleted of their sympathetic nerves by superior cervical ganglionectomy. In the innervated nasal mucosa, exogenous tritiated norepinephrine ( 3 H-NE) was metabolized mainly to tritiated 3,4-dihydroxyphenylethylene glycol ( 3 HDOPEG) and 3,4-dihydroxy mandelic acid ( 3 HDOMA), whereas after denervation it was metabolized mainly to tritiated normetanephrine ( 3 HNMN). In the denervated mucosa, cocaine(30umol/l) inhibited 3 HNMN formation by 50-60%. Cocaine also inhibited 3 HNMN formation by 60% in the denervated lingual gingiva. It is concluded that the tissues metabolize 3 H-NE via a cocaine-sensitive extraneuronal uptake and O-methylating system similar to that which has been shown to be present in dental pulp. 17 references, 1 table

  3. Influence of calcium-dependent potassium channel blockade and nitric oxide inhibition on norepinephrine-induced contractions in two forms of genetic hypertension

    Czech Academy of Sciences Publication Activity Database

    Líšková, Silvia; Petrová, M.; Karen, Petr; Kuneš, Jaroslav; Zicha, Josef

    2010-01-01

    Roč. 4, č. 3 (2010), s. 128-134 ISSN 1933-1711 R&D Projects: GA AV ČR(CZ) IAA500110902 Institutional research plan: CEZ:AV0Z50110509 Keywords : potassium channels * nitric oxide * norepinephrine Subject RIV: ED - Physiology Impact factor: 0.931, year: 2010

  4. The effect of pertussis toxin (PTX) treatment on blood pressure (BP), norepinephrine pressor responsiveness and BP response to acute nifedipine administration in genetic hypertension

    Czech Academy of Sciences Publication Activity Database

    Zicha, Josef; Pintérová, Mária; Dobešová, Zdenka; Líšková, Silvia; Kuneš, Jaroslav

    2006-01-01

    Roč. 48, č. 4 (2006), s. 773-774 ISSN 0194-911X. [Annual Meeting of the European Council for Cardiovascular Research (ECCR) /11./. 29.09.2006-01.10.2006, La Colle sur Loup] R&D Projects: GA MZd(CZ) NR7786 Keywords : pertussis toxin * blood pressure * norepinephrine * nifedipine Subject RIV: FA - Cardiovascular Diseases incl. Cardiotharic Surgery

  5. Location-dependent excitatory synaptic interactions in pyramidal neuron dendrites.

    Directory of Open Access Journals (Sweden)

    Bardia F Behabadi

    Full Text Available Neocortical pyramidal neurons (PNs receive thousands of excitatory synaptic contacts on their basal dendrites. Some act as classical driver inputs while others are thought to modulate PN responses based on sensory or behavioral context, but the biophysical mechanisms that mediate classical-contextual interactions in these dendrites remain poorly understood. We hypothesized that if two excitatory pathways bias their synaptic projections towards proximal vs. distal ends of the basal branches, the very different local spike thresholds and attenuation factors for inputs near and far from the soma might provide the basis for a classical-contextual functional asymmetry. Supporting this possibility, we found both in compartmental models and electrophysiological recordings in brain slices that the responses of basal dendrites to spatially separated inputs are indeed strongly asymmetric. Distal excitation lowers the local spike threshold for more proximal inputs, while having little effect on peak responses at the soma. In contrast, proximal excitation lowers the threshold, but also substantially increases the gain of distally-driven responses. Our findings support the view that PN basal dendrites possess significant analog computing capabilities, and suggest that the diverse forms of nonlinear response modulation seen in the neocortex, including uni-modal, cross-modal, and attentional effects, could depend in part on pathway-specific biases in the spatial distribution of excitatory synaptic contacts onto PN basal dendritic arbors.

  6. Robust Short-Term Memory without Synaptic Learning

    Science.gov (United States)

    Johnson, Samuel; Marro, J.; Torres, Joaquín J.

    2013-01-01

    Short-term memory in the brain cannot in general be explained the way long-term memory can – as a gradual modification of synaptic weights – since it takes place too quickly. Theories based on some form of cellular bistability, however, do not seem able to account for the fact that noisy neurons can collectively store information in a robust manner. We show how a sufficiently clustered network of simple model neurons can be instantly induced into metastable states capable of retaining information for a short time (a few seconds). The mechanism is robust to different network topologies and kinds of neural model. This could constitute a viable means available to the brain for sensory and/or short-term memory with no need of synaptic learning. Relevant phenomena described by neurobiology and psychology, such as local synchronization of synaptic inputs and power-law statistics of forgetting avalanches, emerge naturally from this mechanism, and we suggest possible experiments to test its viability in more biological settings. PMID:23349664

  7. Robust short-term memory without synaptic learning.

    Directory of Open Access Journals (Sweden)

    Samuel Johnson

    Full Text Available Short-term memory in the brain cannot in general be explained the way long-term memory can--as a gradual modification of synaptic weights--since it takes place too quickly. Theories based on some form of cellular bistability, however, do not seem able to account for the fact that noisy neurons can collectively store information in a robust manner. We show how a sufficiently clustered network of simple model neurons can be instantly induced into metastable states capable of retaining information for a short time (a few seconds. The mechanism is robust to different network topologies and kinds of neural model. This could constitute a viable means available to the brain for sensory and/or short-term memory with no need of synaptic learning. Relevant phenomena described by neurobiology and psychology, such as local synchronization of synaptic inputs and power-law statistics of forgetting avalanches, emerge naturally from this mechanism, and we suggest possible experiments to test its viability in more biological settings.

  8. Robust short-term memory without synaptic learning.

    Science.gov (United States)

    Johnson, Samuel; Marro, J; Torres, Joaquín J

    2013-01-01

    Short-term memory in the brain cannot in general be explained the way long-term memory can--as a gradual modification of synaptic weights--since it takes place too quickly. Theories based on some form of cellular bistability, however, do not seem able to account for the fact that noisy neurons can collectively store information in a robust manner. We show how a sufficiently clustered network of simple model neurons can be instantly induced into metastable states capable of retaining information for a short time (a few seconds). The mechanism is robust to different network topologies and kinds of neural model. This could constitute a viable means available to the brain for sensory and/or short-term memory with no need of synaptic learning. Relevant phenomena described by neurobiology and psychology, such as local synchronization of synaptic inputs and power-law statistics of forgetting avalanches, emerge naturally from this mechanism, and we suggest possible experiments to test its viability in more biological settings.

  9. The computational power of astrocyte mediated synaptic plasticity

    Directory of Open Access Journals (Sweden)

    Rogier eMin

    2012-11-01

    Full Text Available Research in the last two decades has made clear that astrocytes play a crucial role in the brain beyond their functions in energy metabolism and homeostasis. Many studies have shown that astrocytes can dynamically modulate neuronal excitability and synaptic plasticity, and might participate in higher brain functions like learning and memory. With the plethora of astrocyte-mediated signaling processes described in the literature today, the current challenge is to identify which of these processes happen under what physiological condition, and how this shapes information processing and, ultimately, behavior. To answer these questions will require a combination of advanced physiological, genetical and behavioral experiments. Additionally, mathematical modeling will prove crucial for testing predictions on the possible functions of astrocytes in neuronal networks, and to generate novel ideas as to how astrocytes can contribute to the complexity of the brain. Here, we aim to provide an outline of how astrocytes can interact with neurons. We do this by reviewing recent experimental literature on astrocyte-neuron interactions, discussing the dynamic effects of astrocytes on neuronal excitability and short- and long-term synaptic plasticity. Finally, we will outline the potential computational functions that astrocyte-neuron interactions can serve in the brain. We will discuss how astrocytes could govern metaplasticity in the brain, how they might organize the clustering of synaptic inputs, and how they could function as memory elements for neuronal activity. We conclude that astrocytes can enhance the computational power of neuronal networks in previously unexpected ways.

  10. A versatile optical tool for studying synaptic GABAA receptor trafficking.

    Science.gov (United States)

    Lorenz-Guertin, Joshua M; Wilcox, Madeleine R; Zhang, Ming; Larsen, Mads B; Pilli, Jyotsna; Schmidt, Brigitte F; Bruchez, Marcel P; Johnson, Jon W; Waggoner, Alan S; Watkins, Simon C; Jacob, Tija C

    2017-11-15

    Live-cell imaging methods can provide critical real-time receptor trafficking measurements. Here, we describe an optical tool to study synaptic γ-aminobutyric acid (GABA) type A receptor (GABA A R) dynamics through adaptable fluorescent-tracking capabilities. A fluorogen-activating peptide (FAP) was genetically inserted into a GABA A R γ2 subunit tagged with pH-sensitive green fluorescent protein (γ2 pH FAP). The FAP selectively binds and activates Malachite Green (MG) dyes that are otherwise non-fluorescent in solution. γ2 pH FAP GABA A Rs are expressed at the cell surface in transfected cortical neurons, form synaptic clusters and do not perturb neuronal development. Electrophysiological studies show γ2 pH FAP GABA A Rs respond to GABA and exhibit positive modulation upon stimulation with the benzodiazepine diazepam. Imaging studies using γ2 pH FAP-transfected neurons and MG dyes show time-dependent receptor accumulation into intracellular vesicles, revealing constitutive endosomal and lysosomal trafficking. Simultaneous analysis of synaptic, surface and lysosomal receptors using the γ2 pH FAP-MG dye approach reveals enhanced GABA A R turnover following a bicucculine-induced seizure paradigm, a finding not detected by standard surface receptor measurements. To our knowledge, this is the first application of the FAP-MG dye system in neurons, demonstrating the versatility to study nearly all phases of GABA A R trafficking. © 2017. Published by The Company of Biologists Ltd.

  11. Evolution of the aging brain transcriptome and synaptic regulation.

    Directory of Open Access Journals (Sweden)

    Patrick M Loerch

    Full Text Available Alzheimer's disease and other neurodegenerative disorders of aging are characterized by clinical and pathological features that are relatively specific to humans. To obtain greater insight into how brain aging has evolved, we compared age-related gene expression changes in the cortex of humans, rhesus macaques, and mice on a genome-wide scale. A small subset of gene expression changes are conserved in all three species, including robust age-dependent upregulation of the neuroprotective gene apolipoprotein D (APOD and downregulation of the synaptic cAMP signaling gene calcium/calmodulin-dependent protein kinase IV (CAMK4. However, analysis of gene ontology and cell type localization shows that humans and rhesus macaques have diverged from mice due to a dramatic increase in age-dependent repression of neuronal genes. Many of these age-regulated neuronal genes are associated with synaptic function. Notably, genes associated with GABA-ergic inhibitory function are robustly age-downregulated in humans but not in mice at the level of both mRNA and protein. Gene downregulation was not associated with overall neuronal or synaptic loss. Thus, repression of neuronal gene expression is a prominent and recently evolved feature of brain aging in humans and rhesus macaques that may alter neural networks and contribute to age-related cognitive changes.

  12. Binocular Rivalry in a Competitive Neural Network with Synaptic Depression

    KAUST Repository

    Kilpatrick, Zachary P.

    2010-01-01

    We study binocular rivalry in a competitive neural network with synaptic depression. In particular, we consider two coupled hypercolums within primary visual cortex (V1), representing orientation selective cells responding to either left or right eye inputs. Coupling between hypercolumns is dominated by inhibition, especially for neurons with dissimilar orientation preferences. Within hypercolumns, recurrent connectivity is excitatory for similar orientations and inhibitory for different orientations. All synaptic connections are modifiable by local synaptic depression. When the hypercolumns are driven by orthogonal oriented stimuli, it is possible to induce oscillations that are representative of binocular rivalry. We first analyze the occurrence of oscillations in a space-clamped version of the model using a fast-slow analys is, taking advantage of the fact that depression evolves much slower than population activity. We th en analyze the onset of oscillations in the full spatially extended system by carrying out a piecewise smooth stability analysis of single (winner-take-all) and double (fusion) bumps within the network. Although our stability analysis takes into account only instabilities associated with real eigenvalues, it identifies points of instability that are consistent with what is found numerically. In particular, we show that, in regions of parameter space where double bumps are unstable and no single bumps exist, binocular rivalry can arise as a slow alternation between either population supporting a bump. © 2010 Society for Industrial and Applied Mathematics.

  13. Structural Components of Synaptic Plasticity and Memory Consolidation

    Science.gov (United States)

    Bailey, Craig H.; Kandel, Eric R.; Harris, Kristen M.

    2015-01-01

    Consolidation of implicit memory in the invertebrate Aplysia and explicit memory in the mammalian hippocampus are associated with remodeling and growth of preexisting synapses and the formation of new synapses. Here, we compare and contrast structural components of the synaptic plasticity that underlies these two distinct forms of memory. In both cases, the structural changes involve time-dependent processes. Thus, some modifications are transient and may contribute to early formative stages of long-term memory, whereas others are more stable, longer lasting, and likely to confer persistence to memory storage. In addition, we explore the possibility that trans-synaptic signaling mechanisms governing de novo synapse formation during development can be reused in the adult for the purposes of structural synaptic plasticity and memory storage. Finally, we discuss how these mechanisms set in motion structural rearrangements that prepare a synapse to strengthen the same memory and, perhaps, to allow it to take part in other memories as a basis for understanding how their anatomical representation results in the enhanced expression and storage of memories in the brain. PMID:26134321

  14. Dextroamphetamine (but Not Atomoxetine) Induces Reanimation from General Anesthesia: Implications for the Roles of Dopamine and Norepinephrine in Active Emergence

    Science.gov (United States)

    Kenny, Jonathan D.; Taylor, Norman E.; Brown, Emery N.; Solt, Ken

    2015-01-01

    Methylphenidate induces reanimation (active emergence) from general anesthesia in rodents, and recent evidence suggests that dopaminergic neurotransmission is important in producing this effect. Dextroamphetamine causes the direct release of dopamine and norepinephrine, whereas atomoxetine is a selective reuptake inhibitor for norepinephrine. Like methylphenidate, both drugs are prescribed to treat Attention Deficit Hyperactivity Disorder. In this study, we tested the efficacy of dextroamphetamine and atomoxetine for inducing reanimation from general anesthesia in rats. Emergence from general anesthesia was defined by return of righting. During continuous sevoflurane anesthesia, dextroamphetamine dose-dependently induced behavioral arousal and restored righting, but atomoxetine did not (n = 6 each). When the D1 dopamine receptor antagonist SCH-23390 was administered prior to dextroamphetamine under the same conditions, righting was not restored (n = 6). After a single dose of propofol (8 mg/kg IV), the mean emergence times for rats that received normal saline (vehicle) and dextroamphetamine (1 mg/kg IV) were 641 sec and 404 sec, respectively (n = 8 each). The difference was statistically significant. Although atomoxetine reduced mean emergence time to 566 sec (n = 8), this decrease was not statistically significant. Spectral analysis of electroencephalogram recordings revealed that dextroamphetamine and atomoxetine both induced a shift in peak power from δ (0.1–4 Hz) to θ (4–8 Hz) during continuous sevoflurane general anesthesia, which was not observed when animals were pre-treated with SCH-23390. In summary, dextroamphetamine induces reanimation from general anesthesia in rodents, but atomoxetine does not induce an arousal response under the same experimental conditions. This supports the hypothesis that dopaminergic stimulation during general anesthesia produces a robust behavioral arousal response. In contrast, selective noradrenergic stimulation causes

  15. Possible association of norepinephrine transporter -3081(A/T polymorphism with methylphenidate response in attention deficit hyperactivity disorder

    Directory of Open Access Journals (Sweden)

    Shin Min-Sup

    2010-10-01

    Full Text Available Abstract Background Attention-deficit/hyperactivity disorder (ADHD is a heritable disorder characterized by symptoms of inattention and/or hyperactivity/impulsivity. Methylphenidate (MPH has been shown to block the norepinephrine transporter (NET, and genetic investigations have demonstrated that the norepinephrine transporter gene (SLC6A2 is associated with ADHD. The aims of this study were to examine the association of the SLC6A2 -3081(A/T and G1287A polymorphisms with MPH response in ADHD. Methods This study enrolled 112 children and adolescents with ADHD. A response criterion was defined based on the Clinical Global Impression-Improvement (CGI-I score, and the ADHD Rating Scale-IV (ARS score was also assessed at baseline and 8 weeks after MPH treatment. Results We found that the subjects who had the T allele as one of the alleles (A/T or T/T genotypes at the -3081(A/T polymorphism showed a better response to MPH treatment than those with the A/A genotype as measured by the CGI-I. We also found a trend towards a difference in the change of the total ARS scores and hyperactivity/impulsivity subscores between subjects with and without the T allele. No significant association was found between the genotypes of the SLC6A2 G1287A polymorphism and response to ADHD treatment. Conclusion Our findings provide evidence for the involvement of the -3081(A/T polymorphism of SLC6A2 in the modulation of the effectiveness of MPH treatment in ADHD.

  16. Inhibition of serotonin but not norepinephrine transport during development produces delayed, persistent perturbations of emotional behaviors in mice.

    Science.gov (United States)

    Ansorge, Mark S; Morelli, Emanuela; Gingrich, Jay A

    2008-01-02

    Serotonin (5-HT) acts as a neurotransmitter, but also modulates brain maturation during early development. The demonstrated influence of genetic variants on brain function, personality traits, and susceptibility to neuropsychiatric disorders suggests a critical importance of developmental mechanisms. However, little is known about how and when developmentally perturbed 5-HT signaling affects circuitry and resulting behavior. The 5-HT transporter (5-HTT) is a key regulator of extracellular 5-HT levels and we used pharmacologic strategies to manipulate 5-HTT function during development and determine behavioral consequences. Transient exposure to the 5-HTT inhibitors fluoxetine, clomipramine, and citalopram from postnatal day 4 (P4) to P21 produced abnormal emotional behaviors in adult mice. Similar treatment with the norepinephrine transporter (NET) inhibitor, desipramine, did not adversely affect adult behavior, suggesting that 5-HT and norepinephrine (NE) do not share the same effects on brain development. Shifting our period of treatment/testing to P90/P185 failed to mimic the effect of earlier exposure, demonstrating that 5-HT effects on adult behavior are developmentally specific. We have hypothesized that early-life perturbations of 5-HT signaling affect corticolimbic circuits that do not reach maturity until the peri-adolescent period. In support of this idea, we found that abnormal behaviors resulting from postnatal fluoxetine exposure have a post-pubescent onset and persist long after reaching adult age. A better understanding of the underlying 5-HT sensitive circuits and how they are perturbed should lead to new insights into how various genetic polymorphisms confer their risk to carriers. Furthermore, these studies should help determine whether in utero exposure to 5-HTT blocking drugs poses a risk for behavioral abnormalities in later life.

  17. Synthesis and in vivo evaluation of novel radiotracers for the in vivo imaging of the norepinephrine transporter

    International Nuclear Information System (INIS)

    Wilson, Alan A.; Patrick Johnson, David; Mozley, David; Hussey, Doug; Ginovart, Nathalie; Nobrega, Jose; Garcia, Armando; Meyer, Jeffery; Houle, Sylvain

    2003-01-01

    The (R,R) and (S,S) enantiomers of 2-[(2-methoxyphenoxy)phenylmethyl]morpholine (MeNER) have been radiolabelled with carbon-11 in good yield and at high specific activity. These radiotracers are close analogues of reboxetine, a potent and selective ligand for the norepinephrine transporter (NET). They were examined as potential ligands for imaging NET in vivo by positron emission tomography (PET). The in vivo brain distribution of both [ 11 C]-labeled enantiomers were evaluated in rats. Following tail-vein injection of the (R,R)-enantiomer regional brain uptake and washout of radioactivity was homogeneous at all time points examined (5-60 min). In contrast, administration of the (S,S)-enantiomer produced a heterogeneous distribution of radioactivity in brain with highest uptake in the hypothalamus, a NET rich region, and lowest uptake in the striatum, a brain region devoid of NET. Hypothalamus to striatum ratios of 2.5 to one were achieved at 60 min post injection of (S,S)-[ 11 C]-MeNER. Pre-injection of the norepinephrine reuptake inhibitors, reboxetine or desipramine, reduced hypothalamus to striatum ratios to near unity while reuptake inhibitors of dopamine and serotonin had no significant effect on binding. In vitro autoradiography studies (rat brain slices) with (S,S)-[ 11 C]-MeNER produced a regional distribution pattern that was consistent with the reported distribution of NET. (S,S)-[ 11 C]-MeNER has the potential to be the first successful PET ligand to image NET

  18. Dextroamphetamine (but Not Atomoxetine Induces Reanimation from General Anesthesia: Implications for the Roles of Dopamine and Norepinephrine in Active Emergence.

    Directory of Open Access Journals (Sweden)

    Jonathan D Kenny

    Full Text Available Methylphenidate induces reanimation (active emergence from general anesthesia in rodents, and recent evidence suggests that dopaminergic neurotransmission is important in producing this effect. Dextroamphetamine causes the direct release of dopamine and norepinephrine, whereas atomoxetine is a selective reuptake inhibitor for norepinephrine. Like methylphenidate, both drugs are prescribed to treat Attention Deficit Hyperactivity Disorder. In this study, we tested the efficacy of dextroamphetamine and atomoxetine for inducing reanimation from general anesthesia in rats. Emergence from general anesthesia was defined by return of righting. During continuous sevoflurane anesthesia, dextroamphetamine dose-dependently induced behavioral arousal and restored righting, but atomoxetine did not (n = 6 each. When the D1 dopamine receptor antagonist SCH-23390 was administered prior to dextroamphetamine under the same conditions, righting was not restored (n = 6. After a single dose of propofol (8 mg/kg i.v., the mean emergence times for rats that received normal saline (vehicle and dextroamphetamine (1 mg/kg i.v. were 641 sec and 404 sec, respectively (n = 8 each. The difference was statistically significant. Although atomoxetine reduced mean emergence time to 566 sec (n = 8, this decrease was not statistically significant. Spectral analysis of electroencephalogram recordings revealed that dextroamphetamine and atomoxetine both induced a shift in peak power from δ (0.1-4 Hz to θ (4-8 Hz during continuous sevoflurane general anesthesia, which was not observed when animals were pre-treated with SCH-23390. In summary, dextroamphetamine induces reanimation from general anesthesia in rodents, but atomoxetine does not induce an arousal response under the same experimental conditions. This supports the hypothesis that dopaminergic stimulation during general anesthesia produces a robust behavioral arousal response. In contrast, selective noradrenergic stimulation

  19. Dextroamphetamine (but Not Atomoxetine) Induces Reanimation from General Anesthesia: Implications for the Roles of Dopamine and Norepinephrine in Active Emergence.

    Science.gov (United States)

    Kenny, Jonathan D; Taylor, Norman E; Brown, Emery N; Solt, Ken

    2015-01-01

    Methylphenidate induces reanimation (active emergence) from general anesthesia in rodents, and recent evidence suggests that dopaminergic neurotransmission is important in producing this effect. Dextroamphetamine causes the direct release of dopamine and norepinephrine, whereas atomoxetine is a selective reuptake inhibitor for norepinephrine. Like methylphenidate, both drugs are prescribed to treat Attention Deficit Hyperactivity Disorder. In this study, we tested the efficacy of dextroamphetamine and atomoxetine for inducing reanimation from general anesthesia in rats. Emergence from general anesthesia was defined by return of righting. During continuous sevoflurane anesthesia, dextroamphetamine dose-dependently induced behavioral arousal and restored righting, but atomoxetine did not (n = 6 each). When the D1 dopamine receptor antagonist SCH-23390 was administered prior to dextroamphetamine under the same conditions, righting was not restored (n = 6). After a single dose of propofol (8 mg/kg i.v.), the mean emergence times for rats that received normal saline (vehicle) and dextroamphetamine (1 mg/kg i.v.) were 641 sec and 404 sec, respectively (n = 8 each). The difference was statistically significant. Although atomoxetine reduced mean emergence time to 566 sec (n = 8), this decrease was not statistically significant. Spectral analysis of electroencephalogram recordings revealed that dextroamphetamine and atomoxetine both induced a shift in peak power from δ (0.1-4 Hz) to θ (4-8 Hz) during continuous sevoflurane general anesthesia, which was not observed when animals were pre-treated with SCH-23390. In summary, dextroamphetamine induces reanimation from general anesthesia in rodents, but atomoxetine does not induce an arousal response under the same experimental conditions. This supports the hypothesis that dopaminergic stimulation during general anesthesia produces a robust behavioral arousal response. In contrast, selective noradrenergic stimulation causes

  20. Mechanism of norepinephrine release elicited by renal nerve stimulation, veratridine and potassium chloride in the isolated rat kidney

    International Nuclear Information System (INIS)

    el-Din, M.M.; Malik, K.U.

    1987-01-01

    We have investigated the mechanism by which renal nerve stimulation (RNS), veratridine (Vt) and KCl promote release of norepinephrine in the isolated rat kidney perfused with Tyrode's solution and prelabeled with [ 3 H]norepinephrine by examining the overflow of tritium elicited by these stimuli during 1) extracellular Ca++ depletion, 2) alterations in extracellular Na+ concentration and 3) administration of tetrodotoxin, amiloride, LiCl and calcium channel blockers. RNS (1-4 Hz), Vt (15-90 nmol) and KCl (150-500 mumol) produced renal vasoconstriction and enhanced the tritium overflow in a frequency- and concentration-dependent manner, respectively. Omission of Ca++ (1.8 mM) from the perfusion fluid abolished the renal vasoconstriction and the increase in tritium overflow elicited by RNA and KCl and substantially reduced that caused by Vt. Lowering the Na+ concentration in the perfusion medium (from 150 to 25 mM) reduced the overflow of tritium and the renal vasoconstriction caused by RNS (2 Hz) or Vt (45 nmol); the increase in tritium overflow in response to these stimuli was positively correlated with extracellular Na+ (25-150 mM). In contrast, KCl-induced tritium overflow was negatively correlated with extracellular Na+ concentration. Tetrodotoxin (0.3 microM) abolished the effect of RNS and Vt, but not that of KCl, to increase overflow of tritium and to produce renal vasoconstriction. Administration of amiloride (180 microM) enhanced the overflow of tritium but attenuated the associated renal vasoconstriction produced by RNS, Vt and KCl. Replacement of NaCl (75 mM) with equimolar concentration of LiCl enhanced the overflow of tritium elicited by RNS, Vt and KCl; the associated renal vasoconstriction remained unaltered

  1. Synthesis and in vivo evaluation of novel radiotracers for the in vivo imaging of the norepinephrine transporter

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, Alan A. E-mail: aaw@camhpet.on.ca; Patrick Johnson, David; Mozley, David; Hussey, Doug; Ginovart, Nathalie; Nobrega, Jose; Garcia, Armando; Meyer, Jeffery; Houle, Sylvain

    2003-02-01

    The (R,R) and (S,S) enantiomers of 2-[(2-methoxyphenoxy)phenylmethyl]morpholine (MeNER) have been radiolabelled with carbon-11 in good yield and at high specific activity. These radiotracers are close analogues of reboxetine, a potent and selective ligand for the norepinephrine transporter (NET). They were examined as potential ligands for imaging NET in vivo by positron emission tomography (PET). The in vivo brain distribution of both [{sup 11}C]-labeled enantiomers were evaluated in rats. Following tail-vein injection of the (R,R)-enantiomer regional brain uptake and washout of radioactivity was homogeneous at all time points examined (5-60 min). In contrast, administration of the (S,S)-enantiomer produced a heterogeneous distribution of radioactivity in brain with highest uptake in the hypothalamus, a NET rich region, and lowest uptake in the striatum, a brain region devoid of NET. Hypothalamus to striatum ratios of 2.5 to one were achieved at 60 min post injection of (S,S)-[{sup 11}C]-MeNER. Pre-injection of the norepinephrine reuptake inhibitors, reboxetine or desipramine, reduced hypothalamus to striatum ratios to near unity while reuptake inhibitors of dopamine and serotonin had no significant effect on binding. In vitro autoradiography studies (rat brain slices) with (S,S)-[{sup 11}C]-MeNER produced a regional distribution pattern that was consistent with the reported distribution of NET. (S,S)-[{sup 11}C]-MeNER has the potential to be the first successful PET ligand to image NET.

  2. Role of phosphatidylinositol 3-kinase in angiotensin II regulation of norepinephrine neuromodulation in brain neurons of the spontaneously hypertensive rat.

    Science.gov (United States)

    Yang, H; Raizada, M K

    1999-04-01

    Chronic stimulation of norepinephrine (NE) neuromodulation by angiotensin II (Ang II) involves activation of the Ras-Raf-MAP kinase signal transduction pathway in Wistar Kyoto (WKY) rat brain neurons. This pathway is only partially responsible for this heightened action of Ang II in the spontaneously hypertensive rat (SHR) brain neurons. In this study, we demonstrate that the MAP kinase-independent signaling pathway in the SHR neuron involves activation of PI3-kinase and protein kinase B (PKB/Akt). Ang II stimulated PI3-kinase activity in both WKY and SHR brain neurons and was accompanied by its translocation from the cytoplasmic to the nuclear compartment. Although the magnitude of stimulation by Ang II was comparable, the stimulation was more persistent in the SHR neuron compared with the WKY rat neuron. Inhibition of PI3-kinase had no significant effect in the WKY rat neuron. However, it caused a 40-50% attenuation of the Ang II-induced increase in norepinephrine transporter (NET) and tyrosine hydroxylase (TH) mRNAs and [3H]-NE uptake in the SHR neuron. In contrast, inhibition of MAP kinase completely attenuated Ang II stimulation of NET and TH mRNA levels in the WKY rat neuron, whereas it caused only a 45% decrease in the SHR neuron. However, an additive attenuation was observed when both kinases of the SHR neurons were inhibited. Ang II also stimulated PKB/Akt activity in both WKY and SHR neurons. This stimulation was 30% higher and lasted longer in the SHR neuron compared with the WKY rat neuron. In conclusion, these observations demonstrate an exclusive involvement of PI3-kinase-PKB-dependent signaling pathway in a heightened NE neuromodulatory action of Ang II in the SHR neuron. Thus, this study offers an excellent potential for the development of new therapies for the treatment of centrally mediated hypertension.

  3. Fear extinction can be made state-dependent on peripheral epinephrine: role of norepinephrine in the nucleus tractus solitarius.

    Science.gov (United States)

    Rosa, Jessica; Myskiw, Jociane C; Furini, Cristiane R G; Sapiras, Gerson G; Izquierdo, Ivan

    2014-09-01

    We investigate whether the extinction of inhibitory avoidance (IA) learning can be subjected to endogenous state-dependence with systemic injections of epinephrine (E), and whether endogenous norepinephrine (NE) and the nucleus tractus solitarius (NTS)→locus coeruleus→hippocampus/amygdala (HIPP/BLA) pathway participate in this. Rats trained in IA were submitted to two sessions of extinction 24 h apart: In the first, the animals were submitted to a training session of extinction, and in the second they were tested for the retention of extinction. Saline or E were given i.p. immediately after the extinction training (post-extinction training injections) and/or 6 min before the extinction test (pre-extinction test). Post-extinction training E (50 or 100 μg/kg) induced a poor retrieval of extinction in the test session of this task unless an additional E injection (50 μg/kg) was given prior to the extinction test. This suggested state-dependence. Muscimol (0.01 μg/side) microinfused into the NTS prior to the extinction test session blocked E-induced state-dependence. Norepinephrine (NE, 1 μg/side) infused bilaterally into NTS restores the extinction impairment caused by post-extinction training i.p. E. In animals with bilateral NTS blockade induced by muscimol, NE (1 μg/side) given prior to the extinction test into the CA1 region of the dorsal hippocampus or into the basolateral amygdala restored the normal extinction levels that had been impaired by muscimol. These results suggest a role for the NTS→locus coeruleus→HIPP/BLA pathway in the retrieval of extinction, as it has been shown to have in the consolidation of inhibitory avoidance and of object recognition learning. Copyright © 2013 Elsevier Inc. All rights reserved.

  4. Geo-Enabled, Mobile Services

    DEFF Research Database (Denmark)

    Jensen, Christian Søndergaard

    2006-01-01

    We are witnessing the emergence of a global infrastructure that enables the widespread deployment of geo-enabled, mobile services in practice. At the same time, the research community has also paid increasing attention to data management aspects of mobile services. This paper offers me...

  5. Toward genome-enabled mycology.

    Science.gov (United States)

    Hibbett, David S; Stajich, Jason E; Spatafora, Joseph W

    2013-01-01

    Genome-enabled mycology is a rapidly expanding field that is characterized by the pervasive use of genome-scale data and associated computational tools in all aspects of fungal biology. Genome-enabled mycology is integrative and often requires teams of researchers with diverse skills in organismal mycology, bioinformatics and molecular biology. This issue of Mycologia presents the first complete fungal genomes in the history of the journal, reflecting the ongoing transformation of mycology into a genome-enabled science. Here, we consider the prospects for genome-enabled mycology and the technical and social challenges that will need to be overcome to grow the database of complete fungal genomes and enable all fungal biologists to make use of the new data.

  6. Ensemble stacking mitigates biases in inference of synaptic connectivity

    Directory of Open Access Journals (Sweden)

    Brendan Chambers

    2018-03-01

    Full Text Available A promising alternative to directly measuring the anatomical connections in a neuronal population is inferring the connections from the activity. We employ simulated spiking neuronal networks to compare and contrast commonly used inference methods that identify likely excitatory synaptic connections using statistical regularities in spike timing. We find that simple adjustments to standard algorithms improve inference accuracy: A signing procedure improves the power of unsigned mutual-information-based approaches and a correction that accounts for differences in mean and variance of background timing relationships, such as those expected to be induced by heterogeneous firing rates, increases the sensitivity of frequency-based methods. We also find that different inference methods reveal distinct subsets of the synaptic network and each method exhibits different biases in the accurate detection of reciprocity and local clustering. To correct for errors and biases specific to single inference algorithms, we combine methods into an ensemble. Ensemble predictions, generated as a linear combination of multiple inference algorithms, are more sensitive than the best individual measures alone, and are more faithful to ground-truth statistics of connectivity, mitigating biases specific to single inference methods. These weightings generalize across simulated datasets, emphasizing the potential for the broad utility of ensemble-based approaches. Mapping the routing of spikes through local circuitry is crucial for understanding neocortical computation. Under appropriate experimental conditions, these maps can be used to infer likely patterns of synaptic recruitment, linking activity to underlying anatomical connections. Such inferences help to reveal the synaptic implementation of population dynamics and computation. We compare a number of standard functional measures to infer underlying connectivity. We find that regularization impacts measures

  7. Synaptic Correlates of Low-Level Perception in V1.

    Science.gov (United States)

    Gerard-Mercier, Florian; Carelli, Pedro V; Pananceau, Marc; Troncoso, Xoana G; Frégnac, Yves

    2016-04-06

    The computational role of primary visual cortex (V1) in low-level perception remains largely debated. A dominant view assumes the prevalence of higher cortical areas and top-down processes in binding information across the visual field. Here, we investigated the role of long-distance intracortical connections in form and motion processing by measuring, with intracellular recordings, their synaptic impact on neurons in area 17 (V1) of the anesthetized cat. By systematically mapping synaptic responses to stimuli presented in the nonspiking surround of V1 receptive fields, we provide the first quantitative characterization of the lateral functional connectivity kernel of V1 neurons. Our results revealed at the population level two structural-functional biases in the synaptic integration and dynamic association properties of V1 neurons. First, subthreshold responses to oriented stimuli flashed in isolation in the nonspiking surround exhibited a geometric organization around the preferred orientation axis mirroring the psychophysical "association field" for collinear contour perception. Second, apparent motion stimuli, for which horizontal and feedforward synaptic inputs summed in-phase, evoked dominantly facilitatory nonlinear interactions, specifically during centripetal collinear activation along the preferred orientation axis, at saccadic-like speeds. This spatiotemporal integration property, which could constitute the neural correlate of a human perceptual bias in speed detection, suggests that local (orientation) and global (motion) information is already linked within V1. We propose the existence of a "dynamic association field" in V1 neurons, whose spatial extent and anisotropy are transiently updated and reshaped as a function of changes in the retinal flow statistics imposed during natural oculomotor exploration. The computational role of primary visual cortex in low-level perception remains debated. The expression of this "pop-out" perception is often assumed

  8. Spike Pattern Structure Influences Synaptic Efficacy Variability Under STDP and Synaptic Homeostasis. II: Spike Shuffling Methods on LIF Networks

    Directory of Open Access Journals (Sweden)

    Zedong Bi

    2016-08-01

    Full Text Available Synapses may undergo variable changes during plasticity because of the variability of spike patterns such as temporal stochasticity and spatial randomness. Here, we call the variability of synaptic weight changes during plasticity to be efficacy variability. In this paper, we investigate how four aspects of spike pattern statistics (i.e., synchronous firing, burstiness/regularity, heterogeneity of rates and heterogeneity of cross-correlations influence the efficacy variability under pair-wise additive spike-timing dependent plasticity (STDP and synaptic homeostasis (the mean strength of plastic synapses into a neuron is bounded, by implementing spike shuffling methods onto spike patterns self-organized by a network of excitatory and inhibitory leaky integrate-and-fire (LIF neurons. With the increase of the decay time scale of the inhibitory synaptic currents, the LIF network undergoes a transition from asynchronous state to weak synchronous state and then to synchronous bursting state. We first shuffle these spike patterns using a variety of methods, each designed to evidently change a specific pattern statistics; and then investigate the change of efficacy variability of the synapses under STDP and synaptic homeostasis, when the neurons in the network fire according to the spike patterns before and after being treated by a shuffling method. In this way, we can understand how the change of pattern statistics may cause the change of efficacy variability. Our results are consistent with those of our previous study which implements spike-generating models on converging motifs. We also find that burstiness/regularity is important to determine the efficacy variability under asynchronous states, while heterogeneity of cross-correlations is the main factor to cause efficacy variability when the network moves into synchronous bursting states (the states observed in epilepsy.

  9. A robust and scalable neuromorphic communication system by combining synaptic time multiplexing and MIMO-OFDM.

    Science.gov (United States)

    Srinivasa, Narayan; Zhang, Deying; Grigorian, Beayna

    2014-03-01

    This paper describes a novel architecture for enabling robust and efficient neuromorphic communication. The architecture combines two concepts: 1) synaptic time multiplexing (STM) that trades space for speed of processing to create an intragroup communication approach that is firing rate independent and offers more flexibility in connectivity than cross-bar architectures and 2) a wired multiple input multiple output (MIMO) communication with orthogonal frequency division multiplexing (OFDM) techniques to enable a robust and efficient intergroup communication for neuromorphic systems. The MIMO-OFDM concept for the proposed architecture was analyzed by simulating large-scale spiking neural network architecture. Analysis shows that the neuromorphic system with MIMO-OFDM exhibits robust and efficient communication while operating in real time with a high bit rate. Through combining STM with MIMO-OFDM techniques, the resulting system offers a flexible and scalable connectivity as well as a power and area efficient solution for the implementation of very large-scale spiking neural architectures in hardware.

  10. Computer Security Systems Enable Access.

    Science.gov (United States)

    Riggen, Gary

    1989-01-01

    A good security system enables access and protects information from damage or tampering, but the most important aspects of a security system aren't technical. A security procedures manual addresses the human element of computer security. (MLW)

  11. How GNSS Enables Precision Farming

    Science.gov (United States)

    2014-12-01

    Precision farming: Feeding a Growing Population Enables Those Who Feed the World. Immediate and Ongoing Needs - population growth (more to feed) - urbanization (decrease in arable land) Double food production by 2050 to meet world demand. To meet thi...

  12. Synaptic vesicle exocytosis in hippocampal synaptosomes correlates directly with total mitochondrial volume

    Science.gov (United States)

    Ivannikov, Maxim V.; Sugimori, Mutsuyuki; Llinás, Rodolfo R.

    2012-01-01

    Synaptic plasticity in many regions of the central nervous system leads to the continuous adjustment of synaptic strength, which is essential for learning and memory. In this study, we show by visualizing synaptic vesicle release in mouse hippocampal synaptosomes that presynaptic mitochondria and specifically, their capacities for ATP production are essential determinants of synaptic vesicle exocytosis and its magnitude. Total internal reflection microscopy of FM1-43 loaded hippocampal synaptosomes showed that inhibition of mitochondrial oxidative phosphorylation reduces evoked synaptic release. This reduction was accompanied by a substantial drop in synaptosomal ATP levels. However, cytosolic calcium influx was not affected. Structural characterization of stimulated hippocampal synaptosomes revealed that higher total presynaptic mitochondrial volumes were consistently associated with higher levels of exocytosis. Thus, synaptic vesicle release is linked to the presynaptic ability to regenerate ATP, which itself is a utility of mitochondrial density and activity. PMID:22772899

  13. Distinct Subunit Domains Govern Synaptic Stability and Specificity of the Kainate Receptor

    Directory of Open Access Journals (Sweden)

    Christoph Straub

    2016-07-01

    Full Text Available Synaptic communication between neurons requires the precise localization of neurotransmitter receptors to the correct synapse type. Kainate-type glutamate receptors restrict synaptic localization that is determined by the afferent presynaptic connection. The mechanisms that govern this input-specific synaptic localization remain unclear. Here, we examine how subunit composition and specific subunit domains contribute to synaptic localization of kainate receptors. The cytoplasmic domain of the GluK2 low-affinity subunit stabilizes kainate receptors at synapses. In contrast, the extracellular domain of the GluK4/5 high-affinity subunit synergistically controls the synaptic specificity of kainate receptors through interaction with C1q-like proteins. Thus, the input-specific synaptic localization of the native kainate receptor complex involves two mechanisms that underlie specificity and stabilization of the receptor at synapses.

  14. Compensating for Thalamocortical Synaptic Loss in Alzheimer’s Disease

    Directory of Open Access Journals (Sweden)

    Kamal eAbuhassan

    2014-06-01

    Full Text Available The study presents a thalamocortical network model which oscillates within the alpha frequency band (8-13 Hz as recorded in the wakeful relaxed state with closed eyes to study the neural causes of abnormal oscillatory activity in Alzheimer’s disease (AD. Incorporated within the model are various types of cortical excitatory and inhibitory neurons, recurrently connected to thalamic and reticular thalamic regions with the ratios and distances derived from the mammalian thalamocortical system. The model is utilized to study the impacts of four types of connectivity loss on the model’s spectral dynamics. The study focuses on investigating degeneration of corticocortical, thalamocortical, corticothalamic and corticoreticular couplings, with an emphasis on the influence of each modelled case on the spectral output of the model. Synaptic compensation has been included in each model to examine the interplay between synaptic deletion and compensation mechanisms, and the oscillatory activity of the network. The results of power spectra and event related desynchronisation/synchronisation (ERD/S analyses show that the dynamics of the thalamic and cortical oscillations are significantly influenced by corticocortical synaptic loss. Interestingly, the patterns of changes in thalamic spectral activity are correlated with those in the cortical model. Similarly, the thalamic oscillatory activity is diminished after partial corticothalamic denervation. The results suggest that thalamic atrophy is a secondary pathology to cortical shrinkage in Alzheimer’s disease. In addition, this study finds that the inhibition from neurons in the thalamic reticular nucleus (RTN to thalamic relay (TCR neurons plays a key role in regulating thalamic oscillations; disinhibition disrupts thalamic oscillatory activity even though TCR neurons are more depolarized after being released from RTN inhibition. This study provides information that can be explored experimentally to

  15. Frequency dependent changes in NMDAR-dependent synaptic plasticity

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    Arvind eKumar

    2011-09-01

    Full Text Available The NMDAR-dependent synaptic plasticity is thought to mediate several forms of learning, and can be induced by spike trains containing a small number of spikes occurring with varying rates and timing, as well as with oscillations. We computed the influence of these variables on the plasticity induced at a single NMDAR containing synapse using a reduced model that was analytically tractable, and these findings were confirmed using detailed, multi-compartment model. In addition to explaining diverse experimental results about the rate and timing dependence of synaptic plasticity, the model made several novel and testable predictions. We found that there was a preferred frequency for inducing long-term potentiation (LTP such that higher frequency stimuli induced lesser LTP, decreasing as 1/f when the number of spikes in the stimulus was kept fixed. Among other things, the preferred frequency for inducing LTP varied as a function of the distance of the synapse from the soma. In fact, same stimulation frequencies could induce LTP or LTD depending on the dendritic location of the synapse. Next, we found that rhythmic stimuli induced greater plasticity then irregular stimuli. Furthermore, brief bursts of spikes significantly expanded the timing dependence of plasticity. Finally, we found that in the ~5-15Hz frequency range both rate- and timing-dependent plasticity mechanisms work synergistically to render the synaptic plasticity most sensitive to spike-timing. These findings provide computational evidence that oscillations can have a profound influence on the plasticity of an NMDAR-dependent synapse, and show a novel role for the dendritic morphology in this process.

  16. Addiction-like Synaptic Impairments in Diet-Induced Obesity.

    Science.gov (United States)

    Brown, Robyn Mary; Kupchik, Yonatan Michael; Spencer, Sade; Garcia-Keller, Constanza; Spanswick, David C; Lawrence, Andrew John; Simonds, Stephanie Elise; Schwartz, Danielle Joy; Jordan, Kelsey Ann; Jhou, Thomas Clayton; Kalivas, Peter William

    2017-05-01

    There is increasing evidence that the pathological overeating underlying some forms of obesity is compulsive in nature and therefore contains elements of an addictive disorder. However, direct physiological evidence linking obesity to synaptic plasticity akin to that occurring in addiction is lacking. We sought to establish whether the propensity to diet-induced obesity (DIO) is associated with addictive-like behavior, as well as synaptic impairments in the nucleus accumbens core considered hallmarks of addiction. Sprague Dawley rats were allowed free access to a palatable diet for 8 weeks then separated by weight gain into DIO-prone and DIO-resistant subgroups. Access to palatable food was then restricted to daily operant self-administration sessions using fixed ratio 1, 3, and 5 and progressive ratio schedules. Subsequently, nucleus accumbens brain slices were prepared, and we tested for changes in the ratio between α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) and N-methyl-D-aspartate currents and the ability to exhibit long-term depression. We found that propensity to develop DIO is linked to deficits in the ability to induce long-term depression in the nucleus accumbens, as well as increased potentiation at these synapses as measured by AMPA/N-methyl-D-aspartate currents. Consistent with these impairments, we observed addictive-like behavior in DIO-prone rats, including 1) heightened motivation for palatable food; 2) excessive intake; and 3) increased food seeking when food was unavailable. Our results show overlap between the propensity for DIO and the synaptic changes associated with facets of addictive behavior, supporting partial coincident neurological underpinnings for compulsive overeating and drug addiction. Copyright © 2016 Society of Biological Psychiatry. All rights reserved.

  17. Astrocytes mediate in vivo cholinergic-induced synaptic plasticity.

    Directory of Open Access Journals (Sweden)

    Marta Navarrete

    2012-02-01

    Full Text Available Long-term potentiation (LTP of synaptic transmission represents the cellular basis of learning and memory. Astrocytes have been shown to regulate synaptic transmission and plasticity. However, their involvement in specific physiological processes that induce LTP in vivo remains unknown. Here we show that in vivo cholinergic activity evoked by sensory stimulation or electrical stimulation of the septal nucleus increases Ca²⁺ in hippocampal astrocytes and induces LTP of CA3-CA1 synapses, which requires cholinergic muscarinic (mAChR and metabotropic glutamate receptor (mGluR activation. Stimulation of cholinergic pathways in hippocampal slices evokes astrocyte Ca²⁺ elevations, postsynaptic depolarizations of CA1 pyramidal neurons, and LTP of transmitter release at single CA3-CA1 synapses. Like in vivo, these effects are mediated by mAChRs, and this cholinergic-induced LTP (c-LTP also involves mGluR activation. Astrocyte Ca²⁺ elevations and LTP are absent in IP₃R2 knock-out mice. Downregulating astrocyte Ca²⁺ signal by loading astrocytes with BAPTA or GDPβS also prevents LTP, which is restored by simultaneous astrocyte Ca²⁺ uncaging and postsynaptic depolarization. Therefore, cholinergic-induced LTP requires astrocyte Ca²⁺ elevations, which stimulate astrocyte glutamate release that activates mGluRs. The cholinergic-induced LTP results from the temporal coincidence of the postsynaptic activity and the astrocyte Ca²⁺ signal simultaneously evoked by cholinergic activity. Therefore, the astrocyte Ca²⁺ signal is necessary for cholinergic-induced synaptic plasticity, indicating that astrocytes are directly involved in brain storage information.

  18. Addiction-like synaptic impairments in diet-induced obesity

    Science.gov (United States)

    Spencer, Sade; Garcia-Keller, Constanza; Spanswick, David C; Lawrence, Andrew John; Simonds, Stephanie Elise; Schwartz, Danielle Joy; Jordan, Kelsey Ann; Jhou, Thomas Clayton; Kalivas, Peter William

    2016-01-01

    Background There is increasing evidence that the pathological overeating underlying some forms of obesity is compulsive in nature, and therefore contains elements of an addictive disorder. However, direct physiological evidence linking obesity to synaptic plasticity akin to that occurring in addiction is lacking. We sought to establish whether the propensity to diet-induced obesity (DIO) is associated with addictive-like behavior, as well as synaptic impairments in the nucleus accumbens core (NAcore) considered hallmarks of addiction. Methods Sprague-Dawley rats were allowed free access to a palatable diet for 8 weeks then separated by weight gain into DIO prone (OP) and resistant (OR) subgroups. Access to palatable food was then restricted to daily operant self-administration sessions using fixed (FR1, 3 and 5) and progressive ratio (PR) schedules. Subsequently, NAcore brain slices were prepared and we tested for changes in the ratio between AMPA and NMDA currents (AMPA/NMDA) and the ability to exhibit long-term depression (LTD). Results We found that propensity to develop DIO is linked to deficits in the ability to induce LTD in the NAcore, as well as increased potentiation at these synapses as measured by AMPA/NMDA currents. Consistent with these impairments, we observed addictive-like behavior in OP rats, including i) heightened motivation for palatable food (ii) excessive intake and (iii) increased food-seeking when food was unavailable. Conclusions Our results show overlap between the propensity for DIO and the synaptic changes associated with facets of addictive behavior, supporting partial coincident neurological underpinnings for compulsive overeating and drug addiction. PMID:26826876

  19. Two aspects of ASIC function: Synaptic plasticity and neuronal injury.

    Science.gov (United States)

    Huang, Yan; Jiang, Nan; Li, Jun; Ji, Yong-Hua; Xiong, Zhi-Gang; Zha, Xiang-ming

    2015-07-01

    Extracellular brain pH fluctuates in both physiological and disease conditions. The main postsynaptic proton receptor is the acid-sensing ion channels (ASICs). During the past decade, much progress has been made on protons, ASICs, and neurological disease. This review summarizes the recent progress on synaptic role of protons and our current understanding of how ASICs contribute to various types of neuronal injury in the brain. This article is part of the Special Issue entitled 'Acid-Sensing Ion Channels in the Nervous System'. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Synaptic E-I Balance Underlies Efficient Neural Coding.

    Science.gov (United States)

    Zhou, Shanglin; Yu, Yuguo

    2018-01-01

    Both theoretical and experimental evidence indicate that synaptic excitation and inhibition in the cerebral cortex are well-balanced during the resting state and sensory processing. Here, we briefly summarize the evidence for how neural circuits are adjusted to achieve this balance. Then, we discuss how such excitatory and inhibitory balance shapes stimulus representation and information propagation, two basic functions of neural coding. We also point out the benefit of adopting such a balance during neural coding. We conclude that excitatory and inhibitory balance may be a fundamental mechanism underlying efficient coding.

  1. Hydrodynamic flow in a synaptic cleft during exocytosis.

    Science.gov (United States)

    Shneider, M N; Gimatdinov, R S; Skorinkin, A I; Kovyazina, I V; Nikolsky, E E

    2012-01-01

    It is shown that exocytosis in a chemical synapse may be accompanied by "microjet" formation due to the overpressure that exists in the vesicles. This mechanism may take place either at complete fusion of a vesicle with the presynaptic membrane or in the so-called kiss-and-run mode of neurotransmitter release. A simple hydrodynamic model of the viscous incompressible flow arising in the synaptic cleft is suggested. The occurrence of hydrodynamic flow (microjet) leads to more efficient transport of neurotransmitter than in the case of classical diffusive transport.

  2. Intense synaptic activity enhances temporal resolution in spinal motoneurons

    DEFF Research Database (Denmark)

    Berg, Rune W; Ditlevsen, Susanne; Hounsgaard, Jørn Dybkjær

    2008-01-01

    In neurons, spike timing is determined by integration of synaptic potentials in delicate concert with intrinsic properties. Although the integration time is functionally crucial, it remains elusive during network activity. While mechanisms of rapid processing are well documented in sensory systems...... of their occurrence and detected for less than 10 ms after their occurrence. Being shorter than the average inter-spike interval, the AHP has little effect on integration time and spike timing, which instead is entirely determined by fluctuations in membrane potential caused by the barrage of inhibitory...

  3. Mammalian Vestibular Macular Synaptic Plasticity: Results from SLS-2 Spaceflight

    Science.gov (United States)

    Ross, Muriel D.D.

    1994-01-01

    The effects of exposure to microgravity were studied in rat utricular maculas collected inflight (IF, day 13), post-flight on day of orbiter landing (day 14, R+O) and after 14 days (R+ML). Controls were collected at corresponding times. The objectives were 1) to learn whether hair cell ribbon synapses counts would be higher in tissues collected in space than in tissues collected postflight during or after readaptation to Earth's gravity; and 2) to compare results with those of SLS-1. Maculas were fixed by immersion, micro-dissected, dehydrated and prepared for ultrastructural study by usual methods. Synapses were counted in 100 serial sections 150 nm thick and were located to specific hair cells in montages of every 7th section. Counts were analyzed for statistical significance using analysis of variance. Results in maculas of IF dissected rats, one 13 day control (IFC), and one R + 0 rat have been analyzed. Study of an R+ML macula is nearly completed. For type I cells, IF mean is 2.3 +/-1.6; IFC mean is 1.6 +/-1.0; R+O mean is 2.3 +/- 1.6. For type II cells, IF mean is 11.4 +/- 17.1; IFC mean is 5.5 +/-3.5; R+O mean is 10.1 +/- 7.4. The difference between IF and IFC means for type I cells is statistically significant (p less than 0.0464). For type It cells, IF compared to IFC means, p less than 0.0003; and for IFC to R+O means, p less than 0.0139. Shifts toward spheres (p less than 0.0001) and pairs (p less than 0.0139) were significant in type II cells of IF rats. The results are largely replicating findings from SLS-1 and indicate that spaceflight affects synaptic number, form and distribution, particularly in type II hair cells. The increases in synaptic number and in sphere-like ribbons are interpreted to improve synaptic efficacy, to help return afferent discharges to a more normal state. Findings indicate that a great capacity for synaptic plasticity exists in mammalian gravity sensors, and that this plasticity is more dominant in the local circuitry. The

  4. Norepinephrine genes predict response time variability and methylphenidate-induced changes in neuropsychological function in attention deficit hyperactivity disorder.

    Science.gov (United States)

    Kim, Bung-Nyun; Kim, Jae-Won; Cummins, Tarrant D R; Bellgrove, Mark A; Hawi, Ziarih; Hong, Soon-Beom; Yang, Young-Hui; Kim, Hyo-Jin; Shin, Min-Sup; Cho, Soo-Churl; Kim, Ji-Hoon; Son, Jung-Woo; Shin, Yun-Mi; Chung, Un-Sun; Han, Doug-Hyun

    2013-06-01

    Noradrenergic dysfunction may be associated with cognitive impairments in attention-deficit/hyperactivity disorder (ADHD), including increased response time variability, which has been proposed as a leading endophenotype for ADHD. The aim of this study was to examine the relationship between polymorphisms in the α-2A-adrenergic receptor (ADRA2A) and norepinephrine transporter (SLC6A2) genes and attentional performance in ADHD children before and after pharmacological treatment.One hundred one medication-naive ADHD children were included. All subjects were administered methylphenidate (MPH)-OROS for 12 weeks. The subjects underwent a computerized comprehensive attention test to measure the response time variability at baseline before MPH treatment and after 12 weeks. Additive regression analyses controlling for ADHD symptom severity, age, sex, IQ, and final dose of MPH examined the association between response time variability on the comprehensive attention test measures and allelic variations in single-nucleotide polymorphisms of the ADRA2A and SLC6A2 before and after MPH treatment.Increasing possession of an A allele at the G1287A polymorphism of SLC6A2 was significantly related to heightened response time variability at baseline in the sustained (P = 2.0 × 10) and auditory selective attention (P = 1.0 × 10) tasks. Response time variability at baseline increased additively with possession of the T allele at the DraI polymorphism of the ADRA2A gene in the auditory selective attention task (P = 2.0 × 10). After medication, increasing possession of a G allele at the MspI polymorphism of the ADRA2A gene was associated with increased MPH-related change in response time variability in the flanker task (P = 1.0 × 10).Our study suggested an association between norepinephrine gene variants and response time variability measured at baseline and after MPH treatment in children with ADHD. Our results add to a growing body of evidence, suggesting that response time

  5. Influence of neonatal and adult hyperthyroidism on behavior and biosynthetic capacity for norepinephrine, dopamine and 5-hydroxytryptamine in rat brain.

    Science.gov (United States)

    Rastogi, R B; Singhal, R L

    1976-09-01

    In neonatal rats, administration of l-triiodothyronine (10 mug/100 g/day) for 30 days presented signs of hyperthyroidism which included accelerated development of a variety of physical and behavioral characteristics accompanying maturation. The spontaneous motor activity was increased by 69%. Exposure of developing rats to thyroid hormone significantly increased the endogenous concentration of striatal tyrosine and the activity of tyrosine hydroxylase as well as the levels of dopamine in several brain regions. The concentration of striatal homovanillic acid and 3,4-dihydroxyphenylacetic acid, the chief metabolites of dopamine, was also increased and the magnitude of change was greater than the rise in dopamine. Despite increases in the activity of tyrosine hydroxylase and the availability of the substrate tyrosine, the steady-state levels of norepinephrine remained unaltered in various regions of brain except in cerebellum. Futhermore, neonatal hyperthyroidism significantly increased the levels of midbrain tryptophan and tryptophan hydroxylase activity but produced no change in 5-hydroxytryptamine levels of several discrete brain regions, except hypothalamus and cerebellum where its concentration was slightly decreased. However, the 5-hydroxyindoleacetic acid levels were enhanced in hypothalamus, ponsmedulla, midbrain, striatum and hippocampus. The elevated levels of 5-hydroxyindoleacetic acid did not seem to be due to increased intraneuronal deamination of 5-hydroxytryptamine since monoamine oxidase activity was not affected in cerebral cortex and midbrain of hyperthyroid rats. The data demonstrate that hyperthyroidism significantly increased the synthesis as well as the utilization of catecholamines and 5-hydroxytryptamine in maturing brain. Since the mature brain is known to respond differently to thyroid hormone action than does the developing brain, the effect of L-triiodothyronine treatment on various putative neurohumors also was examined in adult rats

  6. [The predictive value of dynamic arterial elastance in arterial pressure response after norepinephrine dosage reduction in patients with septic shock].

    Science.gov (United States)

    Liang, F M; Yang, T; Dong, L; Hui, J J; Yan, J

    2017-05-01

    Objective: To assess whether dynamic arterial elastance(Ea(dyn))can be used to predict the reduction of arterial pressure after decreasing norepinephrine (NE) dosage in patients with septic shock. Methods: A prospective observational cohort study was conducted. Thirty-two patients with septic shock and mechanical ventilationwere enrolledfrom January 2014 to December 2015 in ICU of Wuxi People's Hospital of Nanjing Medical University. Hemodynamic parameters were recorded by pulse contour cardiac output(PiCCO)monitoring technology before and after decreasing norepinephrine dosage. Ea(dyn) was defined as the ratio of pulse pressure variation (PPV) to stroke volume variation (SVV). Mean arterial pressure(MAP) variation was calculated after decreasing the dose of NE. Response was defined as a ≥15% decrease of MAP. AUC was plotted to assess the value of Ea(dyn) in predicting MAP response. Results: A total of 32 patients were enrolled in our study, with 13 responding to NE dose decrease where as the other 19 did not. Ea(dyn) was lower in responders than in nonresponders (0.77±0.13 vs 1.09±0.31, P blood pressure variation, diastolic blood pressure variation, systemic vascular resistance variation and MAP variation( r =0.621, P =0.000; r =0.735, P =0.000; r =0.756, P =0.000; r =0.568, P =0.000 respectively). However, stoke volume variation, baseline level of systemic vascular resistance and NE baseline dose were not correlated with Ea(dyn) baseline value( r =0.264, P =0.076; r =0.078, P =0.545; r =0.002, P =0.987 respectively). Ea(dyn)≤0.97 predicted a decrease of MAP when decreasing NE dose, with an area under the receiver-operating characteristic curve of 0.85.The sensitivity was 100.0% and specificity was 73.7%. Conclusions: In septic shock patients treated with NE, Ea(dyn) is an index to predict the decrease of arterial pressure in response to NE dose reduction.

  7. OGC® Sensor Web Enablement Standards

    Directory of Open Access Journals (Sweden)

    George Percivall

    2006-09-01

    Full Text Available This article provides a high-level overview of and architecture for the Open Geospatial Consortium (OGC standards activities that focus on sensors, sensor networks, and a concept called the “Sensor Web”. This OGC work area is known as Sensor Web Enablement (SWE. This article has been condensed from "OGC® Sensor Web Enablement: Overview And High Level Architecture," an OGC White Paper by Mike Botts, PhD, George Percivall, Carl Reed, PhD, and John Davidson which can be downloaded from http://www.opengeospatial.org/pt/15540. Readers interested in greater technical and architecture detail can download and read the OGC SWE Architecture Discussion Paper titled “The OGC Sensor Web Enablement Architecture” (OGC document 06-021r1, http://www.opengeospatial.org/pt/14140.

  8. Memory Reactivation Enables Long-Term Prevention of Interference.

    Science.gov (United States)

    Herszage, Jasmine; Censor, Nitzan

    2017-05-22

    The ability of the human brain to successively learn or perform two competing tasks constitutes a major challenge in daily function. Indeed, exposing the brain to two different competing memories within a short temporal offset can induce interference, resulting in deteriorated performance in at least one of the learned memories [1-4]. Although previous studies have investigated online interference and its effects on performance [5-13], whether the human brain can enable long-term prevention of future interference is unknown. To address this question, we utilized the memory reactivation-reconsolidation framework [2, 12] stemming from studies at the synaptic level [14-17], according to which reactivation of a memory enables its update. In a set of experiments, using the motor sequence learning task [18] we report that a unique pairing of reactivating the original memory (right hand) in synchrony with novel memory trials (left hand) prevented future interference between the two memories. Strikingly, these effects were long-term and observed a month following reactivation. Further experiments showed that preventing future interference was not due to practice per se, but rather specifically depended on a limited time window induced by reactivation of the original memory. These results suggest a mechanism according to which memory reactivation enables long-term prevention of interference, possibly by creating an updated memory trace integrating original and novel memories during the reconsolidation time window. The opportunity to induce a long-term preventive effect on memories may enable the utilization of strategies optimizing normal human learning, as well as recovery following neurological insults. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. F42. CHONDROTIN-6 SULFATE CLUSTERS: ASSOCIATION OF SYNAPTIC DOMAINS AND REGULATION OF SYNAPTIC PLASTICITY DURING FEAR LEARNING

    Science.gov (United States)

    Chelini, Gabriele; Berciu, Cristina; Pilobello, Kanoelani; Peter, Durning; Rachel, Jenkins; Kahn, Moazzzam; Ramikie, Teniel; Subramanian, Siva; Ressler, Kerry; Pantazopoulos, Charalampos; Berretta, Sabina

    2018-01-01

    Abstract Background Emerging evidence from our group and others has brought the brain extracellular matrix (ECM) to the forefront of investigations on brain disorders. Our group has shown that organized perisynaptic ECM aggregates, i.e. perineuronal nets (PNNs) are decreased in several brain regions in people with schizophrenia (SZ) and bipolar disorder (BD). PNNs were detected by their expression of specific chondroitin sulfate proteoglycans (CSPGs), main components of the ECM, thought to play a key role in synaptic regulation during development and adulthood. Our studies have also shown that glial cells expressing CSPGs are altered in these disorders, suggesting a link between glial cell and PNN abnormalities. Finally, we have recently shown that novel CSPG structures, bearing a distinct CS-6 sulfation pattern and named CS-6 glial clusters, are decreased in the amygdala of people with SZ and BD. The morphology and function of CS-6 glial clusters is not currently known, but evidence from rodents and on the role of CSPGs in regulating synaptic functions strongly suggest that they may affect synaptic plasticity. We tested this hypothesis using a combination of human postmortem and rodent brain studies. Methods High Resolution electron microscopy was used to investigate the ultrastructural organization of CS-6 glia clusters. A transgenic mouse model expressing green fluorescent protein in a subset of excitatory pyramidal neurons was used to investigate dendritic spines association with CS-6 glia clusters. Mice were exposed to a single session of auditory fear conditioning for a total of 15 minutes. Animals were euthanized 4 hours after behavioral test. Multiplex immunocytochemistry was used to visualize CS-6 clusters. Results In human tissue, we show that CS-6 glia clusters are widespread in several brain regions, including the amygdala, entorhinal cortex, thalamus and hippocampus. Ultrastructural results show that CS-6 glia clusters are formed by CS-6 accumulations

  10. Higher-Order Synaptic Interactions Coordinate Dynamics in Recurrent Networks.

    Directory of Open Access Journals (Sweden)

    Brendan Chambers

    2016-08-01

    Full Text Available Linking synaptic connectivity to dynamics is key to understanding information processing in neocortex. Circuit dynamics emerge from complex interactions of interconnected neurons, necessitating that links between connectivity and dynamics be evaluated at the network level. Here we map propagating activity in large neuronal ensembles from mouse neocortex and compare it to a recurrent network model, where connectivity can be precisely measured and manipulated. We find that a dynamical feature dominates statistical descriptions of propagating activity for both neocortex and the model: convergent clusters comprised of fan-in triangle motifs, where two input neurons are themselves connected. Fan-in triangles coordinate the timing of presynaptic inputs during ongoing activity to effectively generate postsynaptic spiking. As a result, paradoxically, fan-in triangles dominate the statistics of spike propagation even in randomly connected recurrent networks. Interplay between higher-order synaptic connectivity and the integrative properties of neurons constrains the structure of network dynamics and shapes the routing of information in neocortex.

  11. Ensemble stacking mitigates biases in inference of synaptic connectivity.

    Science.gov (United States)

    Chambers, Brendan; Levy, Maayan; Dechery, Joseph B; MacLean, Jason N

    2018-01-01

    A promising alternative to directly measuring the anatomical connections in a neuronal population is inferring the connections from the activity. We employ simulated spiking neuronal networks to compare and contrast commonly used inference methods that identify likely excitatory synaptic connections using statistical regularities in spike timing. We find that simple adjustments to standard algorithms improve inference accuracy: A signing procedure improves the power of unsigned mutual-information-based approaches and a correction that accounts for differences in mean and variance of background timing relationships, such as those expected to be induced by heterogeneous firing rates, increases the sensitivity of frequency-based methods. We also find that different inference methods reveal distinct subsets of the synaptic network and each method exhibits different biases in the accurate detection of reciprocity and local clustering. To correct for errors and biases specific to single inference algorithms, we combine methods into an ensemble. Ensemble predictions, generated as a linear combination of multiple inference algorithms, are more sensitive than the best individual measures alone, and are more faithful to ground-truth statistics of connectivity, mitigating biases specific to single inference methods. These weightings generalize across simulated datasets, emphasizing the potential for the broad utility of ensemble-based approaches.

  12. Synaptic Wnt/GSK3β Signaling Hub in Autism

    Science.gov (United States)

    Caracci, Mario O.; Ávila, Miguel E.; De Ferrari, Giancarlo V.

    2016-01-01

    Hundreds of genes have been associated with autism spectrum disorders (ASDs) and the interaction of weak and de novo variants derive from distinct autistic phenotypes thus making up the “spectrum.” The convergence of these variants in networks of genes associated with synaptic function warrants the study of cell signaling pathways involved in the regulation of the synapse. The Wnt/β-catenin signaling pathway plays a central role in the development and regulation of the central nervous system and several genes belonging to the cascade have been genetically associated with ASDs. In the present paper, we review basic information regarding the role of Wnt/β-catenin signaling in excitatory/inhibitory balance (E/I balance) through the regulation of pre- and postsynaptic compartments. Furthermore, we integrate information supporting the role of the glycogen synthase kinase 3β (GSK3β) in the onset/development of ASDs through direct modulation of Wnt/β-catenin signaling. Finally, given GSK3β activity as key modulator of synaptic plasticity, we explore the potential of this kinase as a therapeutic target for ASD. PMID:26881141

  13. Oxidative Stress, Synaptic Dysfunction, and Alzheimer's Disease.

    Science.gov (United States)

    Tönnies, Eric; Trushina, Eugenia

    2017-01-01

    Alzheimer's disease (AD) is a devastating neurodegenerative disorder without a cure. Most AD cases are sporadic where age represents the greatest risk factor. Lack of understanding of the disease mechanism hinders the development of efficacious therapeutic approaches. The loss of synapses in the affected brain regions correlates best with cognitive impairment in AD patients and has been considered as the early mechanism that precedes neuronal loss. Oxidative stress has been recognized as a contributing factor in aging and in the progression of multiple neurodegenerative diseases including AD. Increased production of reactive oxygen species (ROS) associated with age- and disease-dependent loss of mitochondrial function, altered metal homeostasis, and reduced antioxidant defense directly affect synaptic activity and neurotransmission in neurons leading to cognitive dysfunction. In addition, molecular targets affected by ROS include nuclear and mitochondrial DNA, lipids, proteins, calcium homeostasis, mitochondrial dynamics and function, cellular architecture, receptor trafficking and endocytosis, and energy homeostasis. Abnormal cellular metabolism in turn could affect the production and accumulation of amyloid-β (Aβ) and hyperphosphorylated Tau protein, which independently could exacerbate mitochondrial dysfunction and ROS production, thereby contributing to a vicious cycle. While mounting evidence implicates ROS in the AD etiology, clinical trials with antioxidant therapies have not produced consistent results. In this review, we will discuss the role of oxidative stress in synaptic dysfunction in AD, innovative therapeutic strategies evolved based on a better understanding of the complexity of molecular mechanisms of AD, and the dual role ROS play in health and disease.

  14. Emerging Links between Homeostatic Synaptic Plasticity and Neurological Disease

    Directory of Open Access Journals (Sweden)

    Dion eDickman

    2013-11-01

    Full Text Available Homeostatic signaling systems are ubiquitous forms of biological regulation, having been studied for hundreds of years in the context of diverse physiological processes including body temperature and osmotic balance. However, only recently has this concept been brought to the study of excitatory and inhibitory electrical activity that the nervous system uses to establish and maintain stable communication. Synapses are a primary target of neuronal regulation with a variety of studies over the past 15 years demonstrating that these cellular junctions are under bidirectional homeostatic control. Recent work from an array of diverse systems and approaches has revealed exciting new links between homeostatic synaptic plasticity and a variety of seemingly disparate neurological and psychiatric diseases. These include autism spectrum disorders, intellectual disabilities, schizophrenia, and Fragile X Syndrome. Although the molecular mechanisms through which defective homeostatic signaling may lead to disease pathogenesis remain unclear, rapid progress is likely to be made in the coming years using a powerful combination of genetic, imaging, electrophysiological, and next generation sequencing approaches. Importantly, understanding homeostatic synaptic plasticity at a cellular and molecular level may lead to developments in new therapeutic innovations to treat these diseases. In this review we will examine recent studies that demonstrate homeostatic control of postsynaptic protein translation, retrograde signaling, and presynaptic function that may contribute to the etiology of complex neurological and psychiatric diseases.

  15. Identification of a mouse synaptic glycoprotein gene in cultured neurons.

    Science.gov (United States)

    Yu, Albert Cheung-Hoi; Sun, Chun Xiao; Li, Qiang; Liu, Hua Dong; Wang, Chen Ran; Zhao, Guo Ping; Jin, Meilei; Lau, Lok Ting; Fung, Yin-Wan Wendy; Liu, Shuang

    2005-10-01

    Neuronal differentiation and aging are known to involve many genes, which may also be differentially expressed during these developmental processes. From primary cultured cerebral cortical neurons, we have previously identified various differentially expressed gene transcripts from cultured cortical neurons using the technique of arbitrarily primed PCR (RAP-PCR). Among these transcripts, clone 0-2 was found to have high homology to rat and human synaptic glycoprotein. By in silico analysis using an EST database and the FACTURA software, the full-length sequence of 0-2 was assembled and the clone was named as mouse synaptic glycoprotein homolog 2 (mSC2). DNA sequencing revealed transcript size of mSC2 being smaller than the human and rat homologs. RT-PCR indicated that mSC2 was expressed differentially at various culture days. The mSC2 gene was located in various tissues with higher expression in brain, lung, and liver. Functions of mSC2 in neurons and other tissues remain elusive and will require more investigation.

  16. Spectrotemporal dynamics of auditory cortical synaptic receptive field plasticity.

    Science.gov (United States)

    Froemke, Robert C; Martins, Ana Raquel O

    2011-09-01

    The nervous system must dynamically represent sensory information in order for animals to perceive and operate within a complex, changing environment. Receptive field plasticity in the auditory cortex allows cortical networks to organize around salient features of the sensory environment during postnatal development, and then subsequently refine these representations depending on behavioral context later in life. Here we review the major features of auditory cortical receptive field plasticity in young and adult animals, focusing on modifications to frequency tuning of synaptic inputs. Alteration in the patterns of acoustic input, including sensory deprivation and tonal exposure, leads to rapid adjustments of excitatory and inhibitory strengths that collectively determine the suprathreshold tuning curves of cortical neurons. Long-term cortical plasticity also requires co-activation of subcortical neuromodulatory control nuclei such as the cholinergic nucleus basalis, particularly in adults. Regardless of developmental stage, regulation of inhibition seems to be a general mechanism by which changes in sensory experience and neuromodulatory state can remodel cortical receptive fields. We discuss recent findings suggesting that the microdynamics of synaptic receptive field plasticity unfold as a multi-phase set of distinct phenomena, initiated by disrupting the balance between excitation and inhibition, and eventually leading to wide-scale changes to many synapses throughout the cortex. These changes are coordinated to enhance the representations of newly-significant stimuli, possibly for improved signal processing and language learning in humans. Copyright © 2011 Elsevier B.V. All rights reserved.

  17. Absence of synaptic regulation by phosducin in retinal slices.

    Directory of Open Access Journals (Sweden)

    James H Long

    Full Text Available Phosducin is an abundant photoreceptor protein that binds G-protein βγ subunits and plays a role in modulating synaptic transmission at photoreceptor synapses under both dark-adapted and light-adapted conditions in vivo. To examine the role of phosducin at the rod-to-rod bipolar cell (RBC synapse, we used whole-cell voltage clamp recordings to measure the light-evoked currents from both wild-type (WT and phosducin knockout (Pd(-/- RBCs, in dark- and light-adapted retinal slices. Pd(-/- RBCs showed smaller dim flash responses and steeper intensity-response relationships than WT RBCs, consistent with the smaller rod responses being selectively filtered out by the non-linear threshold at the rod-to-rod bipolar synapse. In addition, Pd(-/- RBCs showed a marked delay in the onset of the light-evoked currents, similar to that of a WT response to an effectively dimmer flash. Comparison of the changes in flash sensitivity in the presence of steady adapting light revealed that Pd(-/- RBCs desensitized less than WT RBCs to the same intensity. These results are quantitatively consistent with the smaller single photon responses of Pd(-/- rods, owing to the known reduction in rod G-protein expression levels in this line. The absence of an additional synaptic phenotype in these experiments suggests that the function of phosducin at the photoreceptor synapse is abolished by the conditions of retinal slice recordings.

  18. The influence of norepinephrine and phenylephrine on cerebral perfusion and oxygenation during propofol-remifentanil and propofol-remifentanil-dexmedetomidine anaesthesia in piglets

    DEFF Research Database (Denmark)

    Mikkelsen, Mai Louise Grandsgaard; Ambrus, Rikard; Rasmussen, Rune

    2018-01-01

    of dexmedetomidine. Cerebral perfusion measured by laser speckle contrast imaging was related to cerebral oxygenation as measured by an intracerebral Licox probe (partial pressure of oxygen) and transcranial near infrared spectroscopy technology (NIRS) (cerebral oxygen saturation). Results During propofol......–remifentanil anaesthesia, increases in blood pressure by norepinephrine and phenylephrine did not change cerebral perfusion significantly, but cerebral partial pressure of oxygen (Licox) increased following vasopressors in both groups and increases following norepinephrine were significant (NBP: P = 0.04, LBP: P = 0......–remifentanil–dexmedetomidine anaesthesia was not followed by significant changes in cerebral perfusion. Licox measures increased significantly following both vasopressors in both groups, whereas the decreases in NIRS measures were only significant in the NBP group. Conclusions Cerebral partial pressure of oxygen measured by Licox...

  19. Role of DHA in aging-related changes in mouse brain synaptic plasma membrane proteome.

    Science.gov (United States)

    Sidhu, Vishaldeep K; Huang, Bill X; Desai, Abhishek; Kevala, Karl; Kim, Hee-Yong

    2016-05-01

    Aging has been related to diminished cognitive function, which could be a result of ineffective synaptic function. We have previously shown that synaptic plasma membrane proteins supporting synaptic integrity and neurotransmission were downregulated in docosahexaenoic acid (DHA)-deprived brains, suggesting an important role of DHA in synaptic function. In this study, we demonstrate aging-induced synaptic proteome changes and DHA-dependent mitigation of such changes using mass spectrometry-based protein quantitation combined with western blot or messenger RNA analysis. We found significant reduction of 15 synaptic plasma membrane proteins in aging brains including fodrin-α, synaptopodin, postsynaptic density protein 95, synaptic vesicle glycoprotein 2B, synaptosomal-associated protein 25, synaptosomal-associated protein-α, N-methyl-D-aspartate receptor subunit epsilon-2 precursor, AMPA2, AP2, VGluT1, munc18-1, dynamin-1, vesicle-associated membrane protein 2, rab3A, and EAAT1, most of which are involved in synaptic transmission. Notably, the first 9 proteins were further reduced when brain DHA was depleted by diet, indicating that DHA plays an important role in sustaining these synaptic proteins downregulated during aging. Reduction of 2 of these proteins was reversed by raising the brain DHA level by supplementing aged animals with an omega-3 fatty acid sufficient diet for 2 months. The recognition memory compromised in DHA-depleted animals was also improved. Our results suggest a potential role of DHA in alleviating aging-associated cognitive decline by offsetting the loss of neurotransmission-regulating synaptic proteins involved in synaptic function. Published by Elsevier Inc.

  20. Pavlovian autoshaping procedures increase plasma corticosterone and levels of norepinephrine and serotonin in prefrontal cortex in rats.

    Science.gov (United States)

    Tomie, Arthur; Tirado, Aidaluz D; Yu, Lung; Pohorecky, Larissa A

    2004-08-12

    Pavlovian autoshaping procedures provide for pairings of a small object conditioned stimulus (CS) with a rewarding substance unconditioned stimulus (US), resulting in the acquisition of complex sequences of CS-directed skeletal-motor responses or autoshaping conditioned responses (CRs). Autoshaping procedures induce higher post-session levels of corticosterone than in controls receiving CS and US randomly, and the enhanced post-session corticosterone levels have been attributed to the appetitive or arousal-inducing effects of autoshaping procedures. Enhanced corticosterone release can be induced by aversive stimulation or stressful situations, where it is often accompanied by higher levels of norepinephrine (NE) and serotonin (5-HT) in prefrontal cortex (PFC) but not in striatum (ST). Effects of autoshaping procedures on post-session corticosterone levels, NE contents in PFC, and 5-HT contents in PFC and ST were investigated in male Long-Evans rats. Post-session blood samples revealed higher corticosterone levels in the CS-US Paired group (n = 46) than in the CS-US Random control group (n = 21), and brain samples revealed higher levels of PFC NE and 5-HT in CS-US Paired group. Striatal 5-HT levels were unaltered by the autoshaping procedures. Autoshaping procedures provide for appetitive stimulation and induce an arousal-like state, as well as simultaneous stress-like changes in plasma corticosterone and monoamine levels in PFC. Autoshaping, therefore, may be useful for the study of endocrine and central processes associated with appetitive conditions.

  1. Effect of the alkaloid (-)cathinone on the release of radioactivity from rabbit atria prelabelled with 3H-norepinephrine

    International Nuclear Information System (INIS)

    Kalix, P.

    1983-01-01

    In certain countries of East Africa and the Arab Peninsula, fresh leaves of the khat shrub are used as a stimulant. The effect of the plant material can be explained by the presence of the phenylalklamine alkaloid (-)cathinone in the leaves, since this substance has been shown to have an amphetamine-like releasing effect on CNS tissue prelabelled with 3 H-dopamine. Characteristically, the chewing of khat is accompanied by sympathomimetic effects, especially at the cardiovascular level. To test whether these might be due to release of neurotransmitter from adrenergic nerve endings, the effect of (-)cathinone on the efflux of radioactivity from isolated rabbit atrium tissue prelabelled with 3 H-norepinephrine was investigated. It was found that, at concentrations below 1 μM, (-)cathinone caused an immediate increase of efflux. The effect was dose-dependent and was potentiated by pretreatment of the rabbits with reserpine. Preincubation of the tissue with desipramine and cocaine prevented the induction of release by (-)cathinone. The results indicate that the alkaloid (-)cathinone has an amphetamine-like releasing effect on noradrenergic nerve endings and they suggest that the cardiovascular symptoms observed during khat consumption are due to release of neurotransmitter from physiologicl storage sites

  2. Social stress engages opioid regulation of locus coeruleus norepinephrine neurons and induces a state of cellular and physical opiate dependence.

    Science.gov (United States)

    Chaijale, Nayla N; Curtis, Andre L; Wood, Susan K; Zhang, Xiao-Yan; Bhatnagar, Seema; Reyes, Beverly As; Van Bockstaele, Elisabeth J; Valentino, Rita J

    2013-09-01

    Stress is implicated in diverse psychiatric disorders including substance abuse. The locus coeruleus-norepinephrine (LC-NE) system is a major stress response system that is also a point of intersection between stress neuromediators and endogenous opioids and so may be a site at which stress can influence drug-taking behaviors. As social stress is a common stressor for humans, this study characterized the enduring impact of repeated social stress on LC neuronal activity. Rats were exposed to five daily consecutive sessions of social stress using the resident-intruder model or control manipulation. LC discharge rate recorded 2 days after the last manipulation was decreased in stressed rats compared with controls. By 10 days after the last manipulation, LC rates were comparable between groups. Systemic administration of the opiate antagonist, naloxone, robustly increased LC discharge rate in a manner suggestive of opiate withdrawal, selectively in stressed rats when administered 2 or 10 days after the last manipulation. This was accompanied by behavioral signs of mild opiate withdrawal. Western blot and electron microscopic studies indicated that repeated social stress decreased corticotropin-releasing factor type 1 receptor and increased μ-opioid receptor levels in the LC. Together, the results suggest that repeated social stress engages endogenous opioid modulation of LC activity and induces signs of cellular and physical opiate dependence that endure after the stress. These cellular effects may predispose individuals with a history of repeated social stress to substance abuse behaviors.

  3. Norepinephrine, {beta}-adrenoceptor and {sup 123}I-MIBG myocardial scintigram in patients with congestive heart failure

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Kenichi; Miyajima, Seiichi; Kusano, Yoriko; Tanabe, Naohito [Tsubame Rosai Hospital, Niigata (Japan); Nagatomo, Takafumi

    1997-06-01

    Authors studied the relationships of norepinephrine (NE), {beta}-adrenoceptor and {sup 123}I-MIBG (meta-iodo-benzylguanidine) uptake in 26 patients with dilated cardiomyopathy or valvulitis. Blood NE concentrations were determined by high performance liquid chromatography in those patients and 10 healthy volunteers, and myocardial NE, in 7 patients and 5 cases without the congestive heart failure. The amounts of beta-receptors in lymphocytes of 21 patients and 7 volunteers and in myocardium obtained at autopsy of 3 patients and 3 other cases were estimated by the radioligand binding assay. Planar and SPECT images were taken at 15 min and 3 hr post intravenous administration of 111 MBq of {sup 123}I-MIBG. In the planar and SPECT images, the ratio heart/mediastinum (H/M) and MIBG uptake were computed respectively. Blood flow was evaluated by {sup 201}Tl scintigraphy. In patients with congestive heart failure, blood NE concentration was elevated and the number of lymphocytic and myocardial receptors was decreased. The H/M ratio was low. Low MIBG uptake was seen at the posterior to lateral wall. (K.H.)

  4. Radioenzymatic paper-chromatographic assay for dopamine and norepinephrine in cerebroventricular cisternal perfusate of cat following administration of cocaine or d-amphetamine

    Energy Technology Data Exchange (ETDEWEB)

    Chiueh, C C; Kopin, I J [National Inst. of Mental Health, Bethesda, MD (USA)

    1978-08-01

    A sensitive radioenzymatic paper chromatographic method was used to measure the endogenous dopamine and norepinephrine content of cerebroventricular cisternal perfusate from cats to provide direct evidence for the catecholamine releasing action of cocaine from brain in vivo. Although relatively less potent than d-emphetamine, cocaine was shown to release endogenous catechloramines, mainly dopamine from the brain. This similarity may be the neurochemical basis for their similar behavioral effects.

  5. Radioenzymatic paper-chromatographic assay for dopamine and norepinephrine in cerebroventricular cisternal perfusate of cat following administration of cocaine or d-amphetamine

    International Nuclear Information System (INIS)

    Chiueh, C.C.; Kopin, I.J.

    1978-01-01

    A sensitive radioenzymatic paper chromatographic method was used to measure the endogenous dopamine and norepinephrine content of cerebroventricular cisternal perfusate from cats to provide direct evidence for the catecholamine releasing action of cocaine from brain in vivo. Although relatively less potent than d-emphetamine, cocaine was shown to release endogenous catechloramines, mainly dopamine from the brain. This similarity may be the neurochemical basis for their similar behavioral effects. (U.K.)

  6. Effects of aging and hypertension on the participation of endothelium-derived constricting factor (EDCF) in norepinephrine-induced contraction of rat femoral artery

    Czech Academy of Sciences Publication Activity Database

    Líšková, Silvia; Petrová, M.; Karen, Petr; Kuneš, Jaroslav; Zicha, Josef

    2011-01-01

    Roč. 667, 1-3 (2011), s. 265-270 ISSN 0014-2999 R&D Projects: GA ČR(CZ) GA305/09/0336; GA AV ČR(CZ) IAA500110902 Institutional research plan: CEZ:AV0Z50110509 Keywords : EDCF * SHR * norepinephrine * L-NNA * indomethacin Subject RIV: FA - Cardiovascular Diseases incl. Cardiotharic Surgery Impact factor: 2.516, year: 2011

  7. A light-stimulated synaptic transistor with synaptic plasticity and memory functions based on InGaZnO_x–Al_2O_3 thin film structure

    International Nuclear Information System (INIS)

    Li, H. K.; Chen, T. P.; Liu, P.; Zhang, Q.; Hu, S. G.; Liu, Y.; Lee, P. S.

    2016-01-01

    In this work, a synaptic transistor based on the indium gallium zinc oxide (IGZO)–aluminum oxide (Al_2O_3) thin film structure, which uses ultraviolet (UV) light pulses as the pre-synaptic stimulus, has been demonstrated. The synaptic transistor exhibits the behavior of synaptic plasticity like the paired-pulse facilitation. In addition, it also shows the brain's memory behaviors including the transition from short-term memory to long-term memory and the Ebbinghaus forgetting curve. The synapse-like behavior and memory behaviors of the transistor are due to the trapping and detrapping processes of the holes, which are generated by the UV pulses, at the IGZO/Al_2O_3 interface and/or in the Al_2O_3 layer.

  8. Effect of pinacidil on norepinephrine- and potassium-induced contractions and membrane potential in rat and human resistance vessels and in rat aorta

    International Nuclear Information System (INIS)

    Videbaek, L.M.; Aalkjaer, C.; Mulvany, M.J.

    1988-01-01

    The effect of pinacidil on contractile responses to norepinephrine, potassium, and membrane potential was examined in rat and human resistance vessels. In some experiments rat aorta was also used. Pinacidil (0.1-30 microM) caused a concentration-dependent relaxation of norepinephrine-induced contractions in all vessels studied. In the same concentration range, pinacidil had only little effect on potassium (125 mM) activated rat mesenteric and femoral resistance vessels. In denervated rat mesenteric resistance vessels, a depolarization with potassium (125 mM) before superimposing a norepinephrine tone markedly diminished the effect of pinacidil. In resting rat mesenteric resistance vessels, pinacidil (1-10 microM) caused a hyperpolarization of 10-15 mV. In rat aorta, pinacidil (10 microM) caused a significant (p less than 0.001) increase in 86 Rb+ efflux rate constant whereas 1 microM had no effect. The results of these experiments indicate that the vasodilating effect may be caused by a hyperpolarization of the vascular smooth muscle cell membrane

  9. Soluble ectodomain of neuroligin 1 decreases synaptic activity by activating metabotropic glutamate receptor 2

    DEFF Research Database (Denmark)

    Gjørlund, Michelle D.; Carlsen, Eva Maria Meier; Kønig, Andreas Bay

    2017-01-01

    Synaptic cell adhesion molecules represent important targets for neuronal activity-dependent proteolysis. Postsynaptic neuroligins (NLs) form trans-synaptic complexes with presynaptic neurexins (NXs). Both NXs and NLs are cleaved from the cell surface by metalloproteases in an activity-dependent ...

  10. Use-Dependent Inhibition of Synaptic Transmission by the Secretion of Intravesicularly Accumulated Antipsychotic Drugs

    DEFF Research Database (Denmark)

    Tischbirek, Carsten H.; Wenzel, Eva M.; Zheng, Fang

    2012-01-01

    Tischbirek et al. find that weak-base antipsychotic drugs are accumulated in synaptic vesicles and are secreted upon exocytosis, leading to increased extracellular drug concentrations following neuronal activity. The secretion of the drugs in turn inhibits synaptic transmission in a use-dependent...

  11. Automatic morphometry of synaptic boutons of cultured cells using granulometric analysis of digital images

    NARCIS (Netherlands)

    Prodanov, D.P.; Heeroma, Joost; Marani, Enrico

    2006-01-01

    Numbers, linear density, and surface area of synaptic boutons can be important parameters in studies on synaptic plasticity in cultured neurons. We present a method for automatic identification and morphometry of boutons based on filtering of digital images using granulometric analysis. Cultures of

  12. Spike Train Auto-Structure Impacts Post-Synaptic Firing and Timing-Based Plasticity

    Science.gov (United States)

    Scheller, Bertram; Castellano, Marta; Vicente, Raul; Pipa, Gordon

    2011-01-01

    Cortical neurons are typically driven by several thousand synapses. The precise spatiotemporal pattern formed by these inputs can modulate the response of a post-synaptic cell. In this work, we explore how the temporal structure of pre-synaptic inhibitory and excitatory inputs impact the post-synaptic firing of a conductance-based integrate and fire neuron. Both the excitatory and inhibitory input was modeled by renewal gamma processes with varying shape factors for modeling regular and temporally random Poisson activity. We demonstrate that the temporal structure of mutually independent inputs affects the post-synaptic firing, while the strength of the effect depends on the firing rates of both the excitatory and inhibitory inputs. In a second step, we explore the effect of temporal structure of mutually independent inputs on a simple version of Hebbian learning, i.e., hard bound spike-timing-dependent plasticity. We explore both the equilibrium weight distribution and the speed of the transient weight dynamics for different mutually independent gamma processes. We find that both the equilibrium distribution of the synaptic weights and the speed of synaptic changes are modulated by the temporal structure of the input. Finally, we highlight that the sensitivity of both the post-synaptic firing as well as the spike-timing-dependent plasticity on the auto-structure of the input of a neuron could be used to modulate the learning rate of synaptic modification. PMID:22203800

  13. Histone Deacetylase Inhibition Facilitates Massed Pattern-Induced Synaptic Plasticity and Memory

    Science.gov (United States)

    Pandey, Kiran; Sharma, Kaushik P.; Sharma, Shiv K.

    2015-01-01

    Massed training is less effective for long-term memory formation than the spaced training. The role of acetylation in synaptic plasticity and memory is now well established. However, the role of this important protein modification in synaptic plasticity induced by massed pattern of stimulation or memory induced by massed training is not well…

  14. Impaired recycling of synaptic vesicles after acute perturbation of the presynaptic actin cytoskeleton

    DEFF Research Database (Denmark)

    Shupliakov, Oleg; Bloom, Ona; Gustafsson, Jenny S

    2002-01-01

    Actin is an abundant component of nerve terminals that has been implicated at multiple steps of the synaptic vesicle cycle, including reversible anchoring, exocytosis, and recycling of synaptic vesicles. In the present study we used the lamprey reticulospinal synapse to examine the role of actin ...

  15. Regulation of Cortical Dynamic Range by Background Synaptic Noise and Feedforward Inhibition.

    Science.gov (United States)

    Khubieh, Ayah; Ratté, Stéphanie; Lankarany, Milad; Prescott, Steven A

    2016-08-01

    The cortex encodes a broad range of inputs. This breadth of operation requires sensitivity to weak inputs yet non-saturating responses to strong inputs. If individual pyramidal neurons were to have a narrow dynamic range, as previously claimed, then staggered all-or-none recruitment of those neurons would be necessary for the population to achieve a broad dynamic range. Contrary to this explanation, we show here through dynamic clamp experiments in vitro and computer simulations that pyramidal neurons have a broad dynamic range under the noisy conditions that exist in the intact brain due to background synaptic input. Feedforward inhibition capitalizes on those noise effects to control neuronal gain and thereby regulates the population dynamic range. Importantly, noise allows neurons to be recruited gradually and occludes the staggered recruitment previously attributed to heterogeneous excitation. Feedforward inhibition protects spike timing against the disruptive effects of noise, meaning noise can enable the gain control required for rate coding without compromising the precise spike timing required for temporal coding. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  16. Loss of mTOR-dependent macroautophagy causes autistic-like synaptic pruning deficits.

    Science.gov (United States)

    Tang, Guomei; Gudsnuk, Kathryn; Kuo, Sheng-Han; Cotrina, Marisa L; Rosoklija, Gorazd; Sosunov, Alexander; Sonders, Mark S; Kanter, Ellen; Castagna, Candace; Yamamoto, Ai; Yue, Zhenyu; Arancio, Ottavio; Peterson, Bradley S; Champagne, Frances; Dwork, Andrew J; Goldman, James; Sulzer, David

    2014-09-03

    Developmental alterations of excitatory synapses are implicated in autism spectrum disorders (ASDs). Here, we report increased dendritic spine density with reduced developmental spine pruning in layer V pyramidal neurons in postmortem ASD temporal lobe. These spine deficits correlate with hyperactivated mTOR and impaired autophagy. In Tsc2 ± ASD mice where mTOR is constitutively overactive, we observed postnatal spine pruning defects, blockade of autophagy, and ASD-like social behaviors. The mTOR inhibitor rapamycin corrected ASD-like behaviors and spine pruning defects in Tsc2 ± mice, but not in Atg7(CKO) neuronal autophagy-deficient mice or Tsc2 ± :Atg7(CKO) double mutants. Neuronal autophagy furthermore enabled spine elimination with no effects on spine formation. Our findings suggest that mTOR-regulated autophagy is required for developmental spine pruning, and activation of neuronal autophagy corrects synaptic pathology and social behavior deficits in ASD models with hyperactivated mTOR. Copyright © 2014 Elsevier Inc. All rights reserved.

  17. Encoding neural and synaptic functionalities in electron spin: A pathway to efficient neuromorphic computing

    Science.gov (United States)

    Sengupta, Abhronil; Roy, Kaushik

    2017-12-01

    Present day computers expend orders of magnitude more computational resources to perform various cognitive and perception related tasks that humans routinely perform every day. This has recently resulted in a seismic shift in the field of computation where research efforts are being directed to develop a neurocomputer that attempts to mimic the human brain by nanoelectronic components and thereby harness its efficiency in recognition problems. Bridging the gap between neuroscience and nanoelectronics, this paper attempts to provide a review of the recent developments in the field of spintronic device based neuromorphic computing. Description of various spin-transfer torque mechanisms that can be potentially utilized for realizing device structures mimicking neural and synaptic functionalities is provided. A cross-layer perspective extending from the device to the circuit and system level is presented to envision the design of an All-Spin neuromorphic processor enabled with on-chip learning functionalities. Device-circuit-algorithm co-simulation framework calibrated to experimental results suggest that such All-Spin neuromorphic systems can potentially achieve almost two orders of magnitude energy improvement in comparison to state-of-the-art CMOS implementations.

  18. A light-stimulated synaptic device based on graphene hybrid phototransistor

    Science.gov (United States)

    Qin, Shuchao; Wang, Fengqiu; Liu, Yujie; Wan, Qing; Wang, Xinran; Xu, Yongbing; Shi, Yi; Wang, Xiaomu; Zhang, Rong

    2017-09-01

    Neuromorphic chips refer to an unconventional computing architecture that is modelled on biological brains. They are increasingly employed for processing sensory data for machine vision, context cognition, and decision making. Despite rapid advances, neuromorphic computing has remained largely an electronic technology, making it a challenge to access the superior computing features provided by photons, or to directly process vision data that has increasing importance to artificial intelligence. Here we report a novel light-stimulated synaptic device based on a graphene-carbon nanotube hybrid phototransistor. Significantly, the device can respond to optical stimuli in a highly neuron-like fashion and exhibits flexible tuning of both short- and long-term plasticity. These features combined with the spatiotemporal processability make our device a capable counterpart to today’s electrically-driven artificial synapses, with superior reconfigurable capabilities. In addition, our device allows for generic optical spike processing, which provides a foundation for more sophisticated computing. The silicon-compatible, multifunctional photosensitive synapse opens up a new opportunity for neural networks enabled by photonics and extends current neuromorphic systems in terms of system complexities and functionalities.

  19. Visual recognition memory, manifest as long-term habituation, requires synaptic plasticity in V1

    Science.gov (United States)

    Cooke, Sam F.; Komorowski, Robert W.; Kaplan, Eitan S.; Gavornik, Jeffrey P.; Bear, Mark F.

    2015-01-01

    Familiarity with stimuli that bring neither reward nor punishment, manifested through behavioural habituation, enables organisms to detect novelty and devote cognition to important elements of the environment. Here we describe in mice a form of long-term behavioural habituation to visual grating stimuli that is selective for stimulus orientation. Orientation-selective habituation (OSH) can be observed both in exploratory behaviour in an open arena, and in a stereotyped motor response to visual stimuli in head-restrained mice. We show that the latter behavioural response, termed a vidget, requires V1. Parallel electrophysiological recordings in V1 reveal that plasticity, in the form of stimulus-selective response potentiation (SRP), occurs in layer 4 of V1 as OSH develops. Local manipulations of V1 that prevent and reverse electrophysiological modifications likewise prevent and reverse memory demonstrated behaviourally. These findings suggest that a form of long-term visual recognition memory is stored via synaptic plasticity in primary sensory cortex. PMID:25599221

  20. Forebrain deletion of αGDI in adult mice worsens the pre-synaptic deficit at cortico-lateral amygdala synaptic connections.

    Directory of Open Access Journals (Sweden)

    Veronica Bianchi

    Full Text Available The GDI1 gene encodes αGDI, which retrieves inactive GDP-bound RAB from membranes to form a cytosolic pool awaiting vesicular release. Mutations in GDI1 are responsible for X-linked Intellectual Disability. Characterization of the Gdi1-null mice has revealed alterations in the total number and distribution of hippocampal and cortical synaptic vesicles, hippocampal short-term synaptic plasticity and specific short-term memory deficits in adult mice, which are possibly caused by alterations of different synaptic vesicle recycling pathways controlled by several RAB GTPases. However, interpretation of these studies is complicated by the complete ablation of Gdi1 in all cells in the brain throughout development. In this study, we generated conditionally gene-targeted mice in which the knockout of Gdi1 is restricted to the forebrain, hippocampus, cortex and amygdala and occurs only during postnatal development. Adult mutant mice reproduce the short-term memory deficit previously reported in Gdi1-null mice. Surprisingly, the delayed ablation of Gdi1 worsens the pre-synaptic phenotype at cortico-amygdala synaptic connections compared to Gdi1-null mice. These results suggest a pivotal role of αGDI via specific RAB GTPases acting specifically in forebrain regions at the pre-synaptic sites involved in memory formation.

  1. Role of the origin of glutamatergic synaptic inputs in controlling synaptic plasticity and its modulation by alcohol in mice nucleus accumbens

    Directory of Open Access Journals (Sweden)

    Gilles Erwann Martin

    2015-07-01

    Full Text Available It is widely accepted that long-lasting changes of synaptic strength in the nucleus accumbens, a brain region involved in drug reward, mediate acute and chronic effects of alcohol. However, our understanding of the mechanisms underlying the effects of alcohol on synaptic plasticity is limited by the fact that the nucleus accumbens receives glutamatergic inputs from distinct brain regions (e.g. the prefrontal cortex, the amygdala and the hippocampus, each region providing different information (e.g. spatial, emotional and cognitive. Combining whole-cell patch-clamp recordings and the optogenetic technique, we examined synaptic plasticity, and its regulation by alcohol, at cortical, hippocampal and amygdala inputs in fresh slices of mouse tissue. We showed that the origin of synaptic inputs determines the basic properties of glutamatergic synaptic transmission, the expression of spike-timing dependent long-term depression (tLTD and long-term potentiation (tLTP and their regulation by alcohol. While we observed both tLTP and tLTD at amygadala and hippocampal synapses, we showed that cortical inputs only undergo tLTD. Functionally, we provide evidence that acute EtOH has little effects on higher order information coming from the prefrontal cortex (PFCx, while severely impacting the ability of emotional and contextual information to induce long-lasting changes of synaptic strength.

  2. Two-Dimensional Bumps in Piecewise Smooth Neural Fields with Synaptic Depression

    KAUST Repository

    Bressloff, Paul C.

    2011-01-01

    We analyze radially symmetric bumps in a two-dimensional piecewise-smooth neural field model with synaptic depression. The continuum dynamics is described in terms of a nonlocal integrodifferential equation, in which the integral kernel represents the spatial distribution of synaptic weights between populations of neurons whose mean firing rate is taken to be a Heaviside function of local activity. Synaptic depression dynamically reduces the strength of synaptic weights in response to increases in activity. We show that in the case of a Mexican hat weight distribution, sufficiently strong synaptic depression can destabilize a stationary bump solution that would be stable in the absence of depression. Numerically it is found that the resulting instability leads to the formation of a traveling spot. The local stability of a bump is determined by solutions to a system of pseudolinear equations that take into account the sign of perturbations around the circular bump boundary. © 2011 Society for Industrial and Applied Mathematics.

  3. Neuronal plasticity in hibernation and the proposed role of the microtubule-associated protein tau as a "master switch" regulating synaptic gain in neuronal networks.

    Science.gov (United States)

    Arendt, Thomas; Bullmann, Torsten

    2013-09-01

    The present paper provides an overview of adaptive changes in brain structure and learning abilities during hibernation as a behavioral strategy used by several mammalian species to minimize energy expenditure under current or anticipated inhospitable environmental conditions. One cellular mechanism that contributes to the regulated suppression of metabolism and thermogenesis during hibernation is reversible phosphorylation of enzymes and proteins, which limits rates of flux through metabolic pathways. Reversible phosphorylation during hibernation also affects synaptic membrane proteins, a process known to be involved in synaptic plasticity. This mechanism of reversible protein phosphorylation also affects the microtubule-associated protein tau, thereby generating a condition that in the adult human brain is associated with aggregation of tau protein to paired helical filaments (PHFs), as observed in Alzheimer's disease. Here, we put forward the concept that phosphorylation of tau is a neuroprotective mechanism to escape NMDA-mediated hyperexcitability of neurons that would otherwise occur during slow gradual cooling of the brain. Phosphorylation of tau and its subsequent targeting to subsynaptic sites might, thus, work as a kind of "master switch," regulating NMDA receptor-mediated synaptic gain in a wide array of neuronal networks, thereby enabling entry into torpor. If this condition lasts too long, however, it may eventually turn into a pathological trigger, driving a cascade of events leading to neurodegeneration, as in Alzheimer's disease or other "tauopathies".

  4. Organizational Enablers for Project Governance

    DEFF Research Database (Denmark)

    Müller, Ralf; Shao, Jingting; Pemsel, Sofia

    and their relationships to organizational success. Based on these results, the authors discovered that organizational enablers (including key factors such as leadership, governance, and influence of project managers) have a critical impact on how organizations operate, adapt to market fluctuations and forces, and make......While corporate culture plays a significant role in the success of any corporation, governance and “governmentality” not only determine how business should be conducted, but also define the policies and procedures organizations follow to achieve business functions and goals. In their book......, Organizational Enablers for Project Governance, Ralf Müller, Jingting Shao, and Sofia Pemsel examine the interaction of governance and governmentality in various types of companies and demonstrate how these factors drive business success and influence project work, efficiency, and profitability. The data...

  5. Aβ-Induced Synaptic Alterations Require the E3 Ubiquitin Ligase Nedd4-1.

    Science.gov (United States)

    Rodrigues, Elizabeth M; Scudder, Samantha L; Goo, Marisa S; Patrick, Gentry N

    2016-02-03

    Alzheimer's disease (AD) is a neurodegenerative disease in which patients experience progressive cognitive decline. A wealth of evidence suggests that this cognitive impairment results from synaptic dysfunction in affected brain regions caused by cleavage of amyloid precursor protein into the pathogenic peptide amyloid-β (Aβ). Specifically, it has been shown that Aβ decreases surface AMPARs, dendritic spine density, and synaptic strength, and also alters synaptic plasticity. The precise molecular mechanisms by which this occurs remain unclear. Here we demonstrate a role for ubiquitination in Aβ-induced synaptic dysfunction in cultured rat neurons. We find that Aβ promotes the ubiquitination of AMPARs, as well as the redistribution and recruitment of Nedd4-1, a HECT E3 ubiquitin ligase we previously demonstrated to target AMPARs for ubiquitination and degradation. Strikingly, we show that Nedd4-1 is required for Aβ-induced reductions in surface AMPARs, synaptic strength, and dendritic spine density. Our findings, therefore, indicate an important role for Nedd4-1 and ubiquitin in the synaptic alterations induced by Aβ. Synaptic changes in Alzheimer's disease (AD) include surface AMPAR loss, which can weaken synapses. In a cell culture model of AD, we found that AMPAR loss correlates with increased AMPAR ubiquitination. In addition, the ubiquitin ligase Nedd4-1, known to ubiquitinate AMPARs, is recruited to synapses in response to Aβ. Strikingly, reducing Nedd4-1 levels in this model prevented surface AMPAR loss and synaptic weakening. These findings suggest that, in AD, Nedd4-1 may ubiquitinate AMPARs to promote their internalization and weaken synaptic strength, similar to what occurs in Nedd4-1's established role in homeostatic synaptic scaling. This is the first demonstration of Aβ-mediated control of a ubiquitin ligase to regulate surface AMPAR expression. Copyright © 2016 the authors 0270-6474/16/361590-06$15.00/0.

  6. 'Ethos' Enabling Organisational Knowledge Creation

    Science.gov (United States)

    Matsudaira, Yoshito

    This paper examines knowledge creation in relation to improvements on the production line in the manufacturing department of Nissan Motor Company and aims to clarify embodied knowledge observed in the actions of organisational members who enable knowledge creation will be clarified. For that purpose, this study adopts an approach that adds a first, second, and third-person's viewpoint to the theory of knowledge creation. Embodied knowledge, observed in the actions of organisational members who enable knowledge creation, is the continued practice of 'ethos' (in Greek) founded in Nissan Production Way as an ethical basis. Ethos is knowledge (intangible) assets for knowledge creating companies. Substantiated analysis classifies ethos into three categories: the individual, team and organisation. This indicates the precise actions of the organisational members in each category during the knowledge creation process. This research will be successful in its role of showing the indispensability of ethos - the new concept of knowledge assets, which enables knowledge creation -for future knowledge-based management in the knowledge society.

  7. Confocal Synaptology: Synaptic Rearrangements in Neurodegenerative Disorders and upon Nervous System Injury

    Directory of Open Access Journals (Sweden)

    Maja Vulovic

    2018-02-01

    Full Text Available The nervous system is a notable exception to the rule that the cell is the structural and functional unit of tissue systems and organs. The functional unit of the nervous system is the synapse, the contact between two nerve cells. As such, synapses are the foci of investigations of nervous system organization and function, as well as a potential readout for the progression of various disorders of the nervous system. In the past decade the development of antibodies specific to presynaptic terminals has enabled us to assess, at the optical, laser scanning microscopy level, these subcellular structures, and has provided a simple method for the quantification of various synapses. Indeed, excitatory (glutamatergic and inhibitory synapses can be visualized using antibodies against the respective vesicular transporters, and choline-acetyl transferase (ChAT immunoreactivity identifies cholinergic synapses throughout the central nervous system. Here we review the results of several studies in which these methods were used to estimate synaptic numbers as the structural equivalent of functional outcome measures in spinal cord and femoral nerve injuries, as well as in genetic mouse models of neurodegeneration, including Alzheimer’s disease (AD. The results implicate disease- and brain region-specific changes in specific types of synapses, which correlate well with the degree of functional deficit caused by the disease process. Additionally, results are reproducible between various studies and experimental paradigms, supporting the reliability of the method. To conclude, this quantitative approach enables fast and reliable estimation of the degree of the progression of neurodegenerative changes and can be used as a parameter of recovery in experimental models.

  8. Elevated blood plasma levels of epinephrine, norepinephrine, tyrosine hydroxylase, TGFβ1, and TNFα associated with high-altitude pulmonary edema in Indian population

    Directory of Open Access Journals (Sweden)

    Pandey P

    2016-08-01

    Full Text Available Priyanka Pandey,1,2 Zahara Ali,1,2 Ghulam Mohammad,3 MA Qadar Pasha1,2 1Functional Genomics Unit, CSIR-Institute of Genomics and Integrative Biology, Delhi, 2Department of Biotechnology, Savitribai Phule Pune University, Pune, 3Department of Medicine, SNM Hospital, Ladakh, Jammu and Kashmir, India Abstract: Biomarkers are essential to unravel the locked pathophysiology of any disease. This study investigated the role of biomarkers and their interactions with each other and with the clinical parameters to study the physiology of high-altitude pulmonary edema (HAPE in HAPE-patients (HAPE-p against adapted highlanders (HLs and healthy sojourners, HAPE-controls (HAPE-c. For this, seven circulatory biomarkers, namely, epinephrine, norepinephrine, tyrosine hydroxylase, transforming growth factor beta 1, tumor necrosis factor alpha (TNFα, platelet-derived growth factor beta beta, and C-reactive protein (CRP, were measured in blood plasma of the three study groups. All the subjects were recruited at ~3,500 m, and clinical features such as arterial oxygen saturation (SaO2, body mass index, and mean arterial pressure were measured. Increased levels of epinephrine, norepinephrine, tyrosine hydroxylase, transforming growth factor-beta 1, and TNFα were observed in HAPE-p against the healthy groups, HAPE-c, and HLs (P<0.0001. CRP levels were decreased in HAPE-p against HAPE-c and HLs (P<0.0001. There was no significant difference or very marginal difference in the levels of these biomarkers in HAPE-c and HLs (P>0.01. Correlation analysis revealed a negative correlation between epinephrine and norepinephrine (P=4.6E-06 in HAPE-p and positive correlation in HAPE-c (P=0.004 and HLs (P=9.78E-07. A positive correlation was observed between TNFα and CRP (P=0.004 in HAPE-p and a negative correlation in HAPE-c (P=4.6E-06. SaO2 correlated negatively with platelet-derived growth factor beta beta (HAPE-p; P=0.05, norepinephrine (P=0.01, and TNFα (P=0.005 and

  9. Disruption of an Evolutionarily Novel Synaptic Expression Pattern in Autism

    Science.gov (United States)

    Jiang, Xi; Hu, Haiyang; Guijarro, Patricia; Mitchell, Amanda; Ely, John J.; Sherwood, Chet C.; Hof, Patrick R.; Qiu, Zilong; Pääbo, Svante; Akbarian, Schahram; Khaitovich, Philipp

    2016-01-01

    Cognitive defects in autism spectrum disorder (ASD) include socialization and communication: key behavioral capacities that separate humans from other species. Here, we analyze gene expression in the prefrontal cortex of 63 autism patients and control individuals, as well as 62 chimpanzees and macaques, from natal to adult age. We show that among all aberrant expression changes seen in ASD brains, a single aberrant expression pattern overrepresented in genes involved synaptic-related pathways is enriched in nucleotide variants linked to autism. Furthermore, only this pattern contains an excess of developmental expression features unique to humans, thus resulting in the disruption of human-specific developmental programs in autism. Several members of the early growth response (EGR) transcription factor family can be implicated in regulation of this aberrant developmental change. Our study draws a connection between the genetic risk architecture of autism and molecular features of cortical development unique to humans. PMID:27685936

  10. Disruption of an Evolutionarily Novel Synaptic Expression Pattern in Autism.

    Directory of Open Access Journals (Sweden)

    Xiling Liu

    2016-09-01

    Full Text Available Cognitive defects in autism spectrum disorder (ASD include socialization and communication: key behavioral capacities that separate humans from other species. Here, we analyze gene expression in the prefrontal cortex of 63 autism patients and control individuals, as well as 62 chimpanzees and macaques, from natal to adult age. We show that among all aberrant expression changes seen in ASD brains, a single aberrant expression pattern overrepresented in genes involved synaptic-related pathways is enriched in nucleotide variants linked to autism. Furthermore, only this pattern contains an excess of developmental expression features unique to humans, thus resulting in the disruption of human-specific developmental programs in autism. Several members of the early growth response (EGR transcription factor family can be implicated in regulation of this aberrant developmental change. Our study draws a connection between the genetic risk architecture of autism and molecular features of cortical development unique to humans.

  11. Selective effect of cell membrane on synaptic neurotransmission

    DEFF Research Database (Denmark)

    Postila, Pekka A.; Vattulainen, Ilpo; Róg, Tomasz

    2016-01-01

    Atomistic molecular dynamics simulations were performed with 13 non-peptidic neurotransmitters (NTs) in three different membrane environments. The results provide compelling evidence that NTs are divided into membrane-binding and membrane-nonbinding molecules. NTs adhere to the postsynaptic membr...... the importance of cell membrane and specific lipids for neurotransmission, should to be of interest to neuroscientists, drug industry and the general public alike.......Atomistic molecular dynamics simulations were performed with 13 non-peptidic neurotransmitters (NTs) in three different membrane environments. The results provide compelling evidence that NTs are divided into membrane-binding and membrane-nonbinding molecules. NTs adhere to the postsynaptic...... membrane surface whenever the ligand-binding sites of their synaptic receptors are buried in the lipid bilayer. In contrast, NTs that have extracellular ligand-binding sites do not have a similar tendency to adhere to the membrane surface. This finding is a seemingly simple yet important addition...

  12. Binding Sites for Amyloid-β Oligomers and Synaptic Toxicity

    Science.gov (United States)

    Smith, Levi M.; Strittmatter, Stephen M.

    2017-01-01

    In Alzheimer’s disease (AD), insoluble and fibrillary amyloid-β (Aβ) peptide accumulates in plaques. However, soluble Aβ oligomers are most potent in creating synaptic dysfunction and loss. Therefore, receptors for Aβ oligomers are hypothesized to be the first step in a neuronal cascade leading to dementia. A number of cell-surface proteins have been described as Aβ binding proteins, and one or more are likely to mediate Aβ oligomer toxicity in AD. Cellular prion protein (PrPC) is a high-affinity Aβ oligomer binding site, and a range of data delineates a signaling pathway leading from Aβ complexation with PrPC to neuronal impairment. Further study of Aβ binding proteins will define the molecular basis of this crucial step in AD pathogenesis. PMID:27940601

  13. Myostatin-like proteins regulate synaptic function and neuronal morphology.

    Science.gov (United States)

    Augustin, Hrvoje; McGourty, Kieran; Steinert, Joern R; Cochemé, Helena M; Adcott, Jennifer; Cabecinha, Melissa; Vincent, Alec; Halff, Els F; Kittler, Josef T; Boucrot, Emmanuel; Partridge, Linda

    2017-07-01

    Growth factors of the TGFβ superfamily play key roles in regulating neuronal and muscle function. Myostatin (or GDF8) and GDF11 are potent negative regulators of skeletal muscle mass. However, expression of myostatin and its cognate receptors in other tissues, including brain and peripheral nerves, suggests a potential wider biological role. Here, we show that Myoglianin (MYO), the Drosophila homolog of myostatin and GDF11, regulates not only body weight and muscle size, but also inhibits neuromuscular synapse strength and composition in a Smad2-dependent manner. Both myostatin and GDF11 affected synapse formation in isolated rat cortical neuron cultures, suggesting an effect on synaptogenesis beyond neuromuscular junctions. We also show that MYO acts in vivo to inhibit synaptic transmission between neurons in the escape response neural circuit of adult flies. Thus, these anti-myogenic proteins act as important inhibitors of synapse function and neuronal growth. © 2017. Published by The Company of Biologists Ltd.

  14. GABA Metabolism and Transport: Effects on Synaptic Efficacy

    Directory of Open Access Journals (Sweden)

    Fabian C. Roth

    2012-01-01

    Full Text Available GABAergic inhibition is an important regulator of excitability in neuronal networks. In addition, inhibitory synaptic signals contribute crucially to the organization of spatiotemporal patterns of network activity, especially during coherent oscillations. In order to maintain stable network states, the release of GABA by interneurons must be plastic in timing and amount. This homeostatic regulation is achieved by several pre- and postsynaptic mechanisms and is triggered by various activity-dependent local signals such as excitatory input or ambient levels of neurotransmitters. Here, we review findings on the availability of GABA for release at presynaptic terminals of interneurons. Presynaptic GABA content seems to be an important determinant of inhibitory efficacy and can be differentially regulated by changing synthesis, transport, and degradation of GABA or related molecules. We will discuss the functional impact of such regulations on neuronal network patterns and, finally, point towards pharmacological approaches targeting these processes.

  15. Multistate Resistive Switching Memory for Synaptic Memory Applications

    KAUST Repository

    Hota, Mrinal Kanti

    2016-07-12

    Reproducible low bias bipolar resistive switching memory in HfZnOx based memristors is reported. The modification of the concentration of oxygen vacancies in the ternary oxide film, which is facilitated by adding ZnO into HfO2, results in improved memory operation by the ternary oxide compared to the single binary oxides. A controlled multistate memory operation is achieved by controlling current compliance and RESET stop voltages. A high DC cyclic stability up to 400 cycles in the multistate memory performance is observed. Conventional synaptic operation in terms of potentiation, depression plasticity, and Ebbinghaus forgetting process are also studied. The memory mechanism is shown to originate from the migration of the oxygen vacancies and modulation of the interfacial layers. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

  16. Neuronal Depolarization Drives Increased Dopamine Synaptic Vesicle Loading via VGLUT.

    Science.gov (United States)

    Aguilar, Jenny I; Dunn, Matthew; Mingote, Susana; Karam, Caline S; Farino, Zachary J; Sonders, Mark S; Choi, Se Joon; Grygoruk, Anna; Zhang, Yuchao; Cela, Carolina; Choi, Ben Jiwon; Flores, Jorge; Freyberg, Robin J; McCabe, Brian D; Mosharov, Eugene V; Krantz, David E; Javitch, Jonathan A; Sulzer, David; Sames, Dalibor; Rayport, Stephen; Freyberg, Zachary

    2017-08-30

    The ability of presynaptic dopamine terminals to tune neurotransmitter release to meet the demands of neuronal activity is critical to neurotransmission. Although vesicle content has been assumed to be static, in vitro data increasingly suggest that cell activity modulates vesicle content. Here, we use a coordinated genetic, pharmacological, and imaging approach in Drosophila to study the presynaptic machinery responsible for these vesicular processes in vivo. We show that cell depolarization increases synaptic vesicle dopamine content prior to release via vesicular hyperacidification. This depolarization-induced hyperacidification is mediated by the vesicular glutamate transporter (VGLUT). Remarkably, both depolarization-induced dopamine vesicle hyperacidification and its dependence on VGLUT2 are seen in ventral midbrain dopamine neurons in the mouse. Together, these data suggest that in response to depolarization, dopamine vesicles utilize a cascade of vesicular transporters to dynamically increase the vesicular pH gradient, thereby increasing dopamine vesicle content. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Memristor-based neural networks: Synaptic versus neuronal stochasticity

    KAUST Repository

    Naous, Rawan

    2016-11-02

    In neuromorphic circuits, stochasticity in the cortex can be mapped into the synaptic or neuronal components. The hardware emulation of these stochastic neural networks are currently being extensively studied using resistive memories or memristors. The ionic process involved in the underlying switching behavior of the memristive elements is considered as the main source of stochasticity of its operation. Building on its inherent variability, the memristor is incorporated into abstract models of stochastic neurons and synapses. Two approaches of stochastic neural networks are investigated. Aside from the size and area perspective, the impact on the system performance, in terms of accuracy, recognition rates, and learning, among these two approaches and where the memristor would fall into place are the main comparison points to be considered.

  18. Adiponectin modulates synaptic plasticity in hippocampal dentate gyrus.

    Science.gov (United States)

    Pousti, Farideh; Ahmadi, Ramesh; Mirahmadi, Fatemeh; Hosseinmardi, Narges; Rohampour, Kambiz

    2018-01-01

    Recent studies have suggested the involvement of some metabolic hormones in memory formation and synaptic plasticity. Insulin dysfunction is known as an essential process in the pathogenesis of sporadic Alzheimer's disease (AD). In this study we examined whether adiponectin (ADN), as an insulin-sensitizing adipokine, could affect hippocampal synaptic plasticity. Field potential recordings were performed on intracerebroventricular (icv) cannulated urethane anesthetized rats. After baseline recording from dentate gyrus (DG) and 10min prior to high/low frequency stimulation (HFS/LFS), 10μl icv ADN (600nm) were injected. The slope of field excitatory postsynaptic potentials (fEPSP) and the amplitude of population spikes (PS) were recorded in response to perforanth path (PP) stimulation. Paired pulse stimuli and ADN injection without any stimulation protocols were also evaluated. Application of ADN before HFS increased PS amplitude recorded in DG significantly (P≤0.05) in comparison to HFS only group. ADN suppressed the potency of LFS to induce long-term depression (LTD), causing a significant difference between fEPSP slope (P≤0.05) and PS amplitude (P≤0.01) between ADN+LFS and ADN group. Paired pulse stimuli applied at 20ms intervals showed more paired pulse facilitation (PPF), when applied after ADN (P≤0.05). ADN induced a chemical long-term potentiation (LTP) in which fEPSP slope and PS amplitude increased significantly (P≤0.01 and P≤0.05, respectively). It is concluded that ADN is able to potentiate the HFS-induced LTP and suppress LFS-induced LTD. ADN caused a chemical LTP, when applied without any tetanic protocol. ADN may enhance the presynaptic release probability. Copyright © 2017. Published by Elsevier B.V.

  19. Pannexin1 stabilizes synaptic plasticity and is needed for learning.

    Directory of Open Access Journals (Sweden)

    Nora Prochnow

    Full Text Available Pannexin 1 (Panx1 represents a class of vertebrate membrane channels, bearing significant sequence homology with the invertebrate gap junction proteins, the innexins and more distant similarities in the membrane topologies and pharmacological sensitivities with gap junction proteins of the connexin family. In the nervous system, cooperation among pannexin channels, adenosine receptors, and K(ATP channels modulating neuronal excitability via ATP and adenosine has been recognized, but little is known about the significance in vivo. However, the localization of Panx1 at postsynaptic sites in hippocampal neurons and astrocytes in close proximity together with the fundamental role of ATP and adenosine for CNS metabolism and cell signaling underscore the potential relevance of this channel to synaptic plasticity and higher brain functions. Here, we report increased excitability and potently enhanced early and persistent LTP responses in the CA1 region of acute slice preparations from adult Panx1(-/- mice. Adenosine application and N-methyl-D-aspartate receptor (NMDAR-blocking normalized this phenotype, suggesting that absence of Panx1 causes chronic extracellular ATP/adenosine depletion, thus facilitating postsynaptic NMDAR activation. Compensatory transcriptional up-regulation of metabotropic glutamate receptor 4 (grm4 accompanies these adaptive changes. The physiological modification, promoted by loss of Panx1, led to distinct behavioral alterations, enhancing anxiety and impairing object recognition and spatial learning in Panx1(-/- mice. We conclude that ATP release through Panx1 channels plays a critical role in maintaining synaptic strength and plasticity in CA1 neurons of the adult hippocampus. This result provides the rationale for in-depth analysis of Panx1 function and adenosine based therapies in CNS disorders.

  20. Synaptic Plasticity in the Bed Nucleus of the Stria Terminalis: Underlying Mechanisms and Potential Ramifications for Reinstatement of Drug- and Alcohol-Seeking Behaviors.

    Science.gov (United States)

    Harris, Nicholas A; Winder, Danny G

    2018-06-13

    The bed nucleus of the stria terminalis (BNST) is a component of the extended amygdala that shows significant changes in activity and plasticity through chronic exposure to drugs and stress. The region is critical for stress- and cue-induced reinstatement of drug-seeking behaviors and is thus a candidate region for the plastic changes that occur in abstinence that prime addicted patients for reinstatement behaviors. Here, we discuss the various forms of long-term potentiation (LTP) and long-term depression (LTD) in the rodent BNST and highlight the way that these changes in excitatory transmission interact with exposure to alcohol and other drugs of abuse, as well as other stressors. In addition, we highlight potential areas for future research in this area, including investigating input- and cell-specific bidirectional changes in activity. As we continue to accrue foundational knowledge in the mechanisms and effects of plasticity in the BNST, molecular targets and treatment strategies that are relevant to reinstatement behaviors will also begin to emerge. Here, we briefly discuss the effects of catecholamine receptor modulators on synaptic plasticity in the BNST due to the role of norepinephrine in LTD and dopamine on the short-term component of LTP as well as the role that signaling at these receptors plays in reinstatement of drug- and alcohol-seeking behaviors. We hope that insights gained on the specific changes in plasticity that occur within the BNST during abstinence from alcohol and other drugs of abuse will provide insight into the biological underpinnings of relapse behavior in human addicts and inform future treatment modalities for addiction that tackle this complex biological problem.