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Sample records for agrp neuron activity

  1. Agrp neuron activity is required for alcohol-induced overeating

    PubMed Central

    Cains, Sarah; Blomeley, Craig; Kollo, Mihaly; Rácz, Romeo; Burdakov, Denis

    2017-01-01

    Alcohol intake associates with overeating in humans. This overeating is a clinical concern, but its causes are puzzling, because alcohol (ethanol) is a calorie-dense nutrient, and calorie intake usually suppresses brain appetite signals. The biological factors necessary for ethanol-induced overeating remain unclear, and societal causes have been proposed. Here we show that core elements of the brain's feeding circuits—the hypothalamic Agrp neurons that are normally activated by starvation and evoke intense hunger—display electrical and biochemical hyperactivity on exposure to dietary doses of ethanol in brain slices. Furthermore, by circuit-specific chemogenetic interference in vivo, we find that the Agrp cell activity is essential for ethanol-induced overeating in the absence of societal factors, in single-housed mice. These data reveal how a widely consumed nutrient can paradoxically sustain brain starvation signals, and identify a biological factor required for appetite evoked by alcohol. PMID:28072397

  2. Fasting activation of AgRP neurons requires NMDA receptors and involves spinogenesis and increased excitatory tone.

    PubMed

    Liu, Tiemin; Kong, Dong; Shah, Bhavik P; Ye, Chianping; Koda, Shuichi; Saunders, Arpiar; Ding, Jun B; Yang, Zongfang; Sabatini, Bernardo L; Lowell, Bradford B

    2012-02-09

    AgRP neuron activity drives feeding and weight gain whereas that of nearby POMC neurons does the opposite. However, the role of excitatory glutamatergic input in controlling these neurons is unknown. To address this question, we generated mice lacking NMDA receptors (NMDARs) on either AgRP or POMC neurons. Deletion of NMDARs from AgRP neurons markedly reduced weight, body fat and food intake whereas deletion from POMC neurons had no effect. Activation of AgRP neurons by fasting, as assessed by c-Fos, Agrp and Npy mRNA expression, AMPA receptor-mediated EPSCs, depolarization and firing rates, required NMDARs. Furthermore, AgRP but not POMC neurons have dendritic spines and increased glutamatergic input onto AgRP neurons caused by fasting was paralleled by an increase in spines, suggesting fasting induced synaptogenesis and spinogenesis. Thus glutamatergic synaptic transmission and its modulation by NMDARs play key roles in controlling AgRP neurons and determining the cellular and behavioral response to fasting.

  3. Central action of FGF19 reduces hypothalamic AGRP/NPY neuron activity and improves glucose metabolism.

    PubMed

    Marcelin, Geneviève; Jo, Young-Hwan; Li, Xiaosong; Schwartz, Gary J; Zhang, Ying; Dun, Nae J; Lyu, Rong-Ming; Blouet, Clémence; Chang, Jaw K; Chua, Streamson

    2014-02-01

    Tight control of glucose excursions has been a long-standing goal of treatment for patients with type 2 diabetes mellitus in order to ameliorate the morbidity and mortality associated with hyperglycemia. Fibroblast growth factor (FGF) 19 is a hormone-like enterokine released postprandially that emerged as a potential therapeutic agent for metabolic disorders, including diabetes and obesity. Remarkably, FGF19 treatment has hypoglycemic actions that remain potent in models of genetic and acquired insulin resistance. Here, we provided evidence that the central nervous system responds to FGF19 administered in the periphery. Then, in two mouse models of insulin resistance, leptin-deficiency and high-fat diet feeding, third intra-cerebro-ventricular infusions of FGF19 improved glycemic status, reduced insulin resistance and potentiated insulin signaling in the periphery. In addition, our study highlights a new mechanism of central FGF19 action, involving the suppression of AGRP/NPY neuronal activity. Overall, our work unveils novel regulatory pathways induced by FGF19 that will be useful in the design of novel strategies to control diabetes in obesity.

  4. AgRP Neurons Control Systemic Insulin Sensitivity via Myostatin Expression in Brown Adipose Tissue.

    PubMed

    Steculorum, Sophie M; Ruud, Johan; Karakasilioti, Ismene; Backes, Heiko; Engström Ruud, Linda; Timper, Katharina; Hess, Martin E; Tsaousidou, Eva; Mauer, Jan; Vogt, Merly C; Paeger, Lars; Bremser, Stephan; Klein, Andreas C; Morgan, Donald A; Frommolt, Peter; Brinkkötter, Paul T; Hammerschmidt, Philipp; Benzing, Thomas; Rahmouni, Kamal; Wunderlich, F Thomas; Kloppenburg, Peter; Brüning, Jens C

    2016-03-24

    Activation of Agouti-related peptide (AgRP) neurons potently promotes feeding, and chronically altering their activity also affects peripheral glucose homeostasis. We demonstrate that acute activation of AgRP neurons causes insulin resistance through impairment of insulin-stimulated glucose uptake into brown adipose tissue (BAT). AgRP neuron activation acutely reprograms gene expression in BAT toward a myogenic signature, including increased expression of myostatin. Interference with myostatin activity improves insulin sensitivity that was impaired by AgRP neurons activation. Optogenetic circuitry mapping reveals that feeding and insulin sensitivity are controlled by both distinct and overlapping projections. Stimulation of AgRP → LHA projections impairs insulin sensitivity and promotes feeding while activation of AgRP → anterior bed nucleus of the stria terminalis (aBNST)vl projections, distinct from AgRP → aBNSTdm projections controlling feeding, mediate the effect of AgRP neuron activation on BAT-myostatin expression and insulin sensitivity. Collectively, our results suggest that AgRP neurons in mice induce not only eating, but also insulin resistance by stimulating expression of muscle-related genes in BAT, revealing a mechanism by which these neurons rapidly coordinate hunger states with glucose homeostasis.

  5. Dynamic GABAergic afferent modulation of AgRP neurons

    PubMed Central

    Garfield, Alastair S; Shah, Bhavik P; Burgess, Christian R; Li, Monica M; Li, Chia; Steger, Jennifer S; Madara, Joseph C; Campbell, John N; Kroeger, Daniel; Scammell, Thomas E; Tannous, Bakhos A; Myers, Martin G; Andermann, Mark L; Krashes, Michael J; Lowell, Bradford B

    2017-01-01

    Agouti-related peptide (AgRP) neurons of the arcuate nucleus of the hypothalamus (ARC) promote homeostatic feeding at times of caloric insufficiency, yet they are rapidly suppressed by food-related sensory cues prior to ingestion. Here we identify a highly selective inhibitory afferent to AgRP neurons that serves as a neural determinant of this rapid modulation. Specifically, GABAergic projections arising from the ventral compartment of the dorsomedial nucleus of the hypothalamus (vDMH) contribute to the pre-consummatory modulation of ARCAgRP neurons. In a manner reciprocal to ARCAgRP neurons, ARC-projecting leptin receptor (LepR)-expressing GABAergic DMH neurons exhibit rapid activation upon availability of food that additionally reflects the relative value of the food. Thus, DMHLepR neurons form part of the sensory network that relays real-time information about the nature and availability of food to dynamically modulate ARCAgRP neuron activity and feeding behavior. PMID:27643429

  6. Arcuate hypothalamic AgRP and putative POMC neurons show opposite changes in spiking across multiple timescales

    PubMed Central

    Mandelblat-Cerf, Yael; Ramesh, Rohan N; Burgess, Christian R; Patella, Paola; Yang, Zongfang; Lowell, Bradford B; Andermann, Mark L

    2015-01-01

    Agouti-related-peptide (AgRP) neurons—interoceptive neurons in the arcuate nucleus of the hypothalamus (ARC)—are both necessary and sufficient for driving feeding behavior. To better understand the functional roles of AgRP neurons, we performed optetrode electrophysiological recordings from AgRP neurons in awake, behaving AgRP-IRES-Cre mice. In free-feeding mice, we observed a fivefold increase in AgRP neuron firing with mounting caloric deficit in afternoon vs morning recordings. In food-restricted mice, as food became available, AgRP neuron firing dropped, yet remained elevated as compared to firing in sated mice. The rapid drop in spiking activity of AgRP neurons at meal onset may reflect a termination of the drive to find food, while residual, persistent spiking may reflect a sustained drive to consume food. Moreover, nearby neurons inhibited by AgRP neuron photostimulation, likely including satiety-promoting pro-opiomelanocortin (POMC) neurons, demonstrated opposite changes in spiking. Finally, firing of ARC neurons was also rapidly modulated within seconds of individual licks for liquid food. These findings suggest novel roles for antagonistic AgRP and POMC neurons in the regulation of feeding behaviors across multiple timescales. DOI: http://dx.doi.org/10.7554/eLife.07122.001 PMID:26159614

  7. Novel hypophysiotropic AgRP2 neurons and pineal cells revealed by BAC transgenesis in zebrafish

    PubMed Central

    Shainer, Inbal; Buchshtab, Adi; Hawkins, Thomas A.; Wilson, Stephen W.; Cone, Roger D.; Gothilf, Yoav

    2017-01-01

    The neuropeptide agouti-related protein (AgRP) is expressed in the arcuate nucleus of the mammalian hypothalamus and plays a key role in regulating food consumption and energy homeostasis. Fish express two agrp genes in the brain: agrp1, considered functionally homologous with the mammalian AgRP, and agrp2. The role of agrp2 and its relationship to agrp1 are not fully understood. Utilizing BAC transgenesis, we generated transgenic zebrafish in which agrp1- and agrp2-expressing cells can be visualized and manipulated. By characterizing these transgenic lines, we showed that agrp1-expressing neurons are located in the ventral periventricular hypothalamus (the equivalent of the mammalian arcuate nucleus), projecting throughout the hypothalamus and towards the preoptic area. The agrp2 gene was expressed in the pineal gland in a previously uncharacterized subgroup of cells. Additionally, agrp2 was expressed in a small group of neurons in the preoptic area that project directly towards the pituitary and form an interface with the pituitary vasculature, suggesting that preoptic AgRP2 neurons are hypophysiotropic. We showed that direct synaptic connection can exist between AgRP1 and AgRP2 neurons in the hypothalamus, suggesting communication and coordination between AgRP1 and AgRP2 neurons and, therefore, probably also between the processes they regulate. PMID:28317906

  8. Gs-coupled GPCR signalling in AgRP neurons triggers sustained increase in food intake

    PubMed Central

    Nakajima, Ken-ichiro; Cui, Zhenzhong; Li, Chia; Meister, Jaroslawna; Cui, Yinghong; Fu, Ou; Smith, Adam S.; Jain, Shalini; Lowell, Bradford B.; Krashes, Michael J.; Wess, Jürgen

    2016-01-01

    Agouti-related peptide (AgRP) neurons of the hypothalamus play a key role in regulating food intake and body weight, by releasing three different orexigenic molecules: AgRP; GABA; and neuropeptide Y. AgRP neurons express various G protein-coupled receptors (GPCRs) with different coupling properties, including Gs-linked GPCRs. At present, the potential role of Gs-coupled GPCRs in regulating the activity of AgRP neurons remains unknown. Here we show that the activation of Gs-coupled receptors expressed by AgRP neurons leads to a robust and sustained increase in food intake. We also provide detailed mechanistic data linking the stimulation of this class of receptors to the observed feeding phenotype. Moreover, we show that this pathway is clearly distinct from other GPCR signalling cascades that are operative in AgRP neurons. Our data suggest that drugs able to inhibit this signalling pathway may become useful for the treatment of obesity. PMID:26743492

  9. An excitatory paraventricular nucleus to AgRP neuron circuit that drives hunger.

    PubMed

    Krashes, Michael J; Shah, Bhavik P; Madara, Joseph C; Olson, David P; Strochlic, David E; Garfield, Alastair S; Vong, Linh; Pei, Hongjuan; Watabe-Uchida, Mitsuko; Uchida, Naoshige; Liberles, Stephen D; Lowell, Bradford B

    2014-03-13

    Hunger is a hard-wired motivational state essential for survival. Agouti-related peptide (AgRP)-expressing neurons in the arcuate nucleus (ARC) at the base of the hypothalamus are crucial to the control of hunger. They are activated by caloric deficiency and, when naturally or artificially stimulated, they potently induce intense hunger and subsequent food intake. Consistent with their obligatory role in regulating appetite, genetic ablation or chemogenetic inhibition of AgRP neurons decreases feeding. Excitatory input to AgRP neurons is important in caloric-deficiency-induced activation, and is notable for its remarkable degree of caloric-state-dependent synaptic plasticity. Despite the important role of excitatory input, its source(s) has been unknown. Here, through the use of Cre-recombinase-enabled, cell-specific neuron mapping techniques in mice, we have discovered strong excitatory drive that, unexpectedly, emanates from the hypothalamic paraventricular nucleus, specifically from subsets of neurons expressing thyrotropin-releasing hormone (TRH) and pituitary adenylate cyclase-activating polypeptide (PACAP, also known as ADCYAP1). Chemogenetic stimulation of these afferent neurons in sated mice markedly activates AgRP neurons and induces intense feeding. Conversely, acute inhibition in mice with caloric-deficiency-induced hunger decreases feeding. Discovery of these afferent neurons capable of triggering hunger advances understanding of how this intense motivational state is regulated.

  10. Arcuate AgRP neurons mediate orexigenic and glucoregulatory actions of ghrelin.

    PubMed

    Wang, Qian; Liu, Chen; Uchida, Aki; Chuang, Jen-Chieh; Walker, Angela; Liu, Tiemin; Osborne-Lawrence, Sherri; Mason, Brittany L; Mosher, Christina; Berglund, Eric D; Elmquist, Joel K; Zigman, Jeffrey M

    2014-02-01

    The hormone ghrelin stimulates eating and helps maintain blood glucose upon caloric restriction. While previous studies have demonstrated that hypothalamic arcuate AgRP neurons are targets of ghrelin, the overall relevance of ghrelin signaling within intact AgRP neurons is unclear. Here, we tested the functional significance of ghrelin action on AgRP neurons using a new, tamoxifen-inducible AgRP-CreER(T2) transgenic mouse model that allows spatiotemporally-controlled re-expression of physiological levels of ghrelin receptors (GHSRs) specifically in AgRP neurons of adult GHSR-null mice that otherwise lack GHSR expression. AgRP neuron-selective GHSR re-expression partially restored the orexigenic response to administered ghrelin and fully restored the lowered blood glucose levels observed upon caloric restriction. The normalizing glucoregulatory effect of AgRP neuron-selective GHSR expression was linked to glucagon rises and hepatic gluconeogenesis induction. Thus, our data indicate that GHSR-containing AgRP neurons are not solely responsible for ghrelin's orexigenic effects but are sufficient to mediate ghrelin's effects on glycemia.

  11. GABAergic signaling by AgRP neurons prevents anorexia via a melanocortin-independent mechanism

    PubMed Central

    Wu, Qi; Palmiter, Richard D.

    2011-01-01

    The hypothalamic arcuate nucleus contains two anatomically and functionally distinct populations of neurons – the agouti-related peptide (AgRP)- and pro-opiomelanocortin (POMC)-expressing neurons that integrate various nutritional, hormonal, and neuronal signals to regulate food intake and energy expenditure, and thereby help achieve energy homeostasis. AgRP neurons, also co-release neuropeptide Y and γ-aminobutyric acid (GABA) to promote feeding and inhibit metabolism through at least three possible mechanisms: (1) suppression of the melanocortin signaling system through competitive binding of AgRP with the melanocortin 4 receptors; (2) neuropeptide Y-mediated inhibition of post-synaptic neurons that reside in hypothalamic nuclei; (3) GABAergic inhibition of POMC neurons in their post-synaptic targets including the parabrachial nucleus (parabrachial nucleus), a brainstem structure that relays gustatory and visceral sensory information. Acute ablation of AgRP neurons in adult mice by the action of diphtheria toxin (DT) results in precipitous reduction of food intake, and eventually leads to starvation within 6 days of DT treatment. Chronic delivery of bretazenil, a GABAA receptor partial agonist, into the parabrachial nucleus is sufficient to restore feeding and body weight when AgRP neurons are ablated, whereas chronic blockade of melanocortin 4 receptor signaling is inadequate. This review summarizes the physiological roles of a neural circuitry regulated by AgRP neurons in control of feeding behavior with particular emphasis of the GABA output to the parabrachial nucleus. We also describe a compensatory mechanism that is gradually engaged after ablation of AgRP neurons that allows mice to continue eating without them. PMID:21211531

  12. Metabolic Benefit of Chronic Caloric Restriction and Activation of Hypothalamic AGRP/NPY Neurons in Male Mice Is Independent of Ghrelin.

    PubMed

    Rogers, Nicole H; Walsh, Heidi; Alvarez-Garcia, Oscar; Park, Seongjoon; Gaylinn, Bruce; Thorner, Michael O; Smith, Roy G

    2016-04-01

    Aging is associated with attenuated ghrelin signaling. During aging, chronic caloric restriction (CR) produces health benefits accompanied by enhanced ghrelin production. Ghrelin receptor (GH secretagogue receptor 1a) agonists administered to aging rodents and humans restore the young adult phenotype; therefore, we tested the hypothesis that the metabolic benefits of CR are mediated by endogenous ghrelin. Three month-old male mice lacking ghrelin (Ghrelin-/-) or ghrelin receptor (Ghsr-/-), and their wild-type (WT) littermates were randomly assigned to 2 groups: ad libitum (AL) fed and CR, where 40% food restriction was introduced gradually to allow Ghrelin-/- and Ghsr-/- mice to metabolically adapt and avoid severe hypoglycemia. Twelve months later, plasma ghrelin, metabolic parameters, ambulatory activity, hypothalamic and liver gene expression, as well as body composition were measured. CR increased plasma ghrelin and des-acyl ghrelin concentrations in WT and Ghsr-/- mice. CR of WT, Ghsr-/-, and Ghrelin-/- mice markedly improved metabolic flexibility, enhanced ambulatory activity, and reduced adiposity. Inactivation of Ghrelin or Ghsr had no effect on AL food intake or food anticipatory behavior. In contrast to the widely held belief that endogenous ghrelin regulates food intake, CR increased expression of hypothalamic Agrp and Npy, with reduced expression of Pomc across genotypes. In the AL context, ablation of ghrelin signaling markedly inhibited liver steatosis, which correlated with reduced Pparγ expression and enhanced Irs2 expression. Although CR and administration of GH secretagogue receptor 1a agonists both benefit the aging phenotype, we conclude the benefits of chronic CR are a consequence of enhanced metabolic flexibility independent of endogenous ghrelin or des-acyl ghrelin signaling.

  13. Agrp neurons mediate Sirt1's action on the melanocortin system and energy balance: roles for Sirt1 in neuronal firing and synaptic plasticity.

    PubMed

    Dietrich, Marcelo O; Antunes, Catiele; Geliang, Gan; Liu, Zhong-Wu; Borok, Erzsebet; Nie, Yongzhan; Xu, Allison W; Souza, Diogo O; Gao, Qian; Diano, Sabrina; Gao, Xiao-Bing; Horvath, Tamas L

    2010-09-01

    Sirt1 has been associated with various effects of calorie restriction, including an increase in lifespan. Here we show in mice that a central regulatory component in energy metabolism, the hypothalamic melanocortin system, is affected by Sirt1, which promotes the activity and connectivity of this system resulting in negative energy balance. In adult mice, the pharmacological inhibition of brain Sirt1 activity decreased Agrp neuronal activity and the inhibitory tone on the anorexigenic POMC neurons, as measured by the number of synaptic inputs to these neurons. When a Sirt1 inhibitor (EX-527) was injected either peripherally (i.p., 10 mg/kg) or directly into the brain (i.c.v., 1.5 nmol/mouse), it decreased both food intake during the dark cycle and ghrelin-induced food intake. This effect on feeding is mediated by upstream melanocortin receptors, because the MC4R antagonist, SHU9119, reversed Sirt1's effect on food intake. This action of Sirt1 required an appropriate shift in the mitochondrial redox state: in the absence of such an adaptation enabled by the mitochondrial protein, UCP2, Sirt1-induced cellular and behavioral responses were impaired. In accordance with the pharmacological results, the selective knock-out of Sirt1 in hypothalamic Agrp neurons through the use of Cre-Lox technology decreased electric responses of Agrp neurons to ghrelin and decreased food intake, leading to decreased lean mass, fat mass, and body weight. The present data indicate that Sirt1 has a central mode of action by acting on the NPY/Agrp neurons to affect body metabolism.

  14. Third ventricular coinjection of subthreshold doses of NPY and AgRP stimulate food hoarding and intake and neural activation.

    PubMed

    Teubner, Brett J W; Keen-Rhinehart, Erin; Bartness, Timothy J

    2012-01-01

    We previously demonstrated that 3rd ventricular (3V) neuropeptide Y (NPY) or agouti-related protein (AgRP) injection potently stimulates food foraging/hoarding/intake in Siberian hamsters. Because NPY and AgRP are highly colocalized in arcuate nucleus neurons in this and other species, we tested whether subthreshold doses of NPY and AgRP coinjected into the 3V stimulates food foraging, hoarding, and intake, and/or neural activation [c-Fos immunoreactivity (c-Fos-ir)] in hamsters housed in a foraging/hoarding apparatus. In the behavioral experiment, each hamster received four 3V treatments by using subthreshold doses of NPY and AgRP for all behaviors: 1) NPY, 2) AgRP, 3) NPY+AgRP, and 4) saline with a 7-day washout period between treatments. Food foraging, intake, and hoarding were measured 1, 2, 4, and 24 h and 2 and 3 days postinjection. Only when NPY and AgRP were coinjected was food intake and hoarding increased. After identical treatment in separate animals, c-Fos-ir was assessed at 90 min and 14 h postinjection, times when food intake (0-1 h) and hoarding (4-24 h) were uniquely stimulated. c-Fos-ir was increased in several hypothalamic nuclei previously shown to be involved in ingestive behaviors and the central nucleus of the amygdala (CeA), but only in NPY+AgRP-treated animals (90 min and 14 h: magno- and parvocellular regions of the hypothalamic paraventricular nucleus and perifornical area; 14 h only: CeA and sub-zona incerta). These results suggest that NPY and AgRP interact to stimulate food hoarding and intake at distinct times, perhaps released as a cocktail naturally with food deprivation to stimulate these behaviors.

  15. Post-embryonic ablation of AgRP neurons in mice leads to a lean, hypophagic phenotype.

    PubMed

    Bewick, Gavin A; Gardiner, James V; Dhillo, Waljit S; Kent, Aysha S; White, Nicholas E; Webster, Zoe; Ghatei, Mohammad A; Bloom, Stephen R

    2005-10-01

    Agouti-related protein (AgRP) and neuropeptide Y (NPY) are colocalized in arcuate nucleus (arcuate) neurons implicated in the regulation of energy balance. Both AgRP and NPY stimulate food intake when administered into the third ventricle and are up-regulated in states of negative energy balance. However, mice with targeted deletion of either NPY or AgRP or both do not have major alterations in energy homeostasis. Using bacterial artificial chromosome (BAC) transgenesis we have targeted expression of a neurotoxic CAG expanded form of ataxin-3 to AgRP-expressing neurons in the arcuate. This resulted in a 47% loss of AgRP neurons by 16 weeks of age, a significantly reduced body weight, (wild-type mice (WT) 34.7+/-0.7 g vs. transgenic mice (Tg) 28.6+/-0.6 g, P<0.001), and reduced food intake (WT 5.0+/-0.2 vs. Tg 3.6+/-0.1 g per day, P<0.001). Transgenic mice had significantly reduced total body fat, plasma insulin, and increased brown adipose tissue UCP1 expression. Transgenic mice failed to respond to peripherally administered ghrelin but retained sensitivity to PYY 3-36. These data suggest that postembryonic partial loss of AgRP/NPY neurons leads to a lean, hypophagic phenotype.

  16. AgRP and POMC Neurons Are Hypophysiotropic and Coordinately Regulate Multiple Endocrine Axes in a Teleost

    PubMed Central

    Zhang, Chao; Forlano, Paul M.; Cone, Roger D.

    2012-01-01

    SUMMARY Plasticity in growth and reproductive behavior is found in many vertebrate species, but is common in male teleost fish. Typically, “bourgeois” males are considerably larger and defend breeding territories while “parasitic” variants are small and use opportunistic breeding strategies. The P locus mediates this phenotypic variation in Xipophorus and encodes variant alleles of the melanocortin-4 receptor (MC4R). However, deletion of the MC4R has modest effects on somatic growth and reproduction in mammals, suggesting a fundamental difference in the neuroendocrine function of central melanocortin signaling in teleosts. Here we show in a teleost that the hypothalamic proopiomelanocortin and AgRP neurons are hypophysiotropic, projecting to the pituitary to coordinately regulate multiple pituitary hormones. Indeed, AgRP-mediated suppression of MC4R appears essential for early larval growth. This identifies the mechanism by which the central melanocortin system coordinately regulates growth and reproduction in teleosts, and suggests it is an important anatomical substrate for evolutionary adaptation. PMID:22245570

  17. AgRP(83-132) and SHU9119 differently affect activity-based anorexia.

    PubMed

    Hillebrand, Jacquelien J G; Kas, Martien J H; Scheurink, Anton J W; van Dijk, Gertjan; Adan, Roger A H

    2006-08-01

    Activity-based anorexia (ABA) mimics starvation and hyperactivity of anorexia nervosa patients in rats. Activation of the melanocortin (MC) system leads to hypophagia and increased energy expenditure in ad libitum fed rats. Therefore, activation of the MC system might underlie the development and propagation of ABA. Pro-opiomelanocortin (POMC) gene expression is normally decreased during negative energy balance. Strikingly, we found a transient up-regulation of POMC mRNA levels in the arcuate nucleus during the development of ABA, indicating a hyperactive MC system. However, wheel running and food intake were not influenced by treating ABA rats with the competitive antagonist SHU9119. This suggests that agonism of MC receptors by endogenous alpha-melanocyte-stimulating hormone (alpha-MSH) levels does not underlie ABA. Instead, treatment with the inverse agonist AgRP(83-132) did ameliorate signs of ABA. This implies that modulation of constitutive MC receptor activity rather than antagonizing putative alpha-MSH release contributes to the development and propagation of ABA.

  18. Somato-Dendritic Localization and Signaling by Leptin Receptors in Hypothalamic POMC and AgRP Neurons

    PubMed Central

    Ha, Sangdeuk; Baver, Scott; Huo, Lihong; Gata, Adriana; Hairston, Joyce; Huntoon, Nicholas; Li, Wenjing; Zhang, Thompson; Benecchi, Elizabeth J.; Ericsson, Maria; Hentges, Shane T.; Bjørbæk, Christian

    2013-01-01

    Leptin acts via neuronal leptin receptors to control energy balance. Hypothalamic pro-opiomelanocortin (POMC) and agouti-related peptide (AgRP)/Neuropeptide Y (NPY)/GABA neurons produce anorexigenic and orexigenic neuropeptides and neurotransmitters, and express the long signaling form of the leptin receptor (LepRb). Despite progress in the understanding of LepRb signaling and function, the sub-cellular localization of LepRb in target neurons has not been determined, primarily due to lack of sensitive anti-LepRb antibodies. Here we applied light microscopy (LM), confocal-laser scanning microscopy (CLSM), and electron microscopy (EM) to investigate LepRb localization and signaling in mice expressing a HA-tagged LepRb selectively in POMC or AgRP/NPY/GABA neurons. We report that LepRb receptors exhibit a somato-dendritic expression pattern. We further show that LepRb activates STAT3 phosphorylation in neuronal fibers within several hypothalamic and hindbrain nuclei of wild-type mice and rats, and specifically in dendrites of arcuate POMC and AgRP/NPY/GABA neurons of Leprb+/+ mice and in Leprbdb/db mice expressing HA-LepRb in a neuron specific manner. We did not find evidence of LepRb localization or STAT3-signaling in axon-fibers or nerve-terminals of POMC and AgRP/NPY/GABA neurons. Three-dimensional serial EM-reconstruction of dendritic segments from POMC and AgRP/NPY/GABA neurons indicates a high density of shaft synapses. In addition, we found that the leptin activates STAT3 signaling in proximity to synapses on POMC and AgRP/NPY/GABA dendritic shafts. Taken together, these data suggest that the signaling-form of the leptin receptor exhibits a somato-dendritic expression pattern in POMC and AgRP/NPY/GABA neurons. Dendritic LepRb signaling may therefore play an important role in leptin’s central effects on energy balance, possibly through modulation of synaptic activity via post-synaptic mechanisms. PMID:24204898

  19. Assessing Interactions Between Ghsr and Mc3r Reveals a Role for AgRP in the Expression of Food Anticipatory Activity in Male Mice

    PubMed Central

    Girardet, Clemence; Mavrikaki, Maria; Southern, Mark R.; Smith, Roy G.

    2014-01-01

    The stomach hormone ghrelin and hypothalamic melanocortin neurons belong to a gut-brain circuit controlling appetite and metabolic homeostasis. Mice lacking melanocortin-3 receptor (Mc3rKO) or growth hormone secretagogue receptor (GhsrKO) genes exhibit attenuated food anticipatory activity (FAA), a rise in locomotor activity anticipating mealtime, suggesting common circuitry regulating anticipatory responses to nutrient loading. To investigate the interaction between Ghsrs and Mc3rs, we compared food anticipatory responses in GhsrKO, Mc3rKO, and double Ghsr;Mc3r knockout (DKO) mice subjected to a hypocaloric restricted feeding (RF) protocol in constant dark or 12-hour light, 12-hour dark settings. DKO are viable, exhibiting no overt behavioral or metabolic phenotypes in ad libitum or fasting conditions. FAA was initially attenuated in all mutant strains in constant darkness. However, GhsrKO eventually exhibited a robust food anticipatory response, suggesting compensation. Mc3rKO and DKO did not compensate, indicating a continued requirement for Mc3rs in maintaining the expression of FAA in situations of RF. Abnormal regulation of hypothalamic agouti-related peptide/neuropeptide Y (AgRP/Npy) neurons previously observed during fasting may contribute to attenuated FAA in Mc3rKO. AgRP and Npy expression measured 1 hour before food presentation correlated positively with FAA. Absence of Mc3rs (but not Ghsrs) was associated with lower AgRP/Npy expression, suggesting attenuated responses to signals of negative energy balance. These observations support the importance of Mc3rs as modulators of anticipatory responses to feeding, with mice able to compensate for loss of Ghsrs. The behavioral deficits of Mc3rKO displayed during RF may be partially explained by reduced hunger sensations owing to abnormal regulation of orexigenic AgRP/Npy neurons. PMID:25211592

  20. Hunger neurons drive feeding through a sustained, positive reinforcement signal.

    PubMed

    Chen, Yiming; Lin, Yen-Chu; Zimmerman, Christopher A; Essner, Rachel A; Knight, Zachary A

    2016-08-24

    The neural mechanisms underlying hunger are poorly understood. AgRP neurons are activated by energy deficit and promote voracious food consumption, suggesting these cells may supply the fundamental hunger drive that motivates feeding. However recent in vivo recording experiments revealed that AgRP neurons are inhibited within seconds by the sensory detection of food, raising the question of how these cells can promote feeding at all. Here we resolve this paradox by showing that brief optogenetic stimulation of AgRP neurons before food availability promotes intense appetitive and consummatory behaviors that persist for tens of minutes in the absence of continued AgRP neuron activation. We show that these sustained behavioral responses are mediated by a long-lasting potentiation of the rewarding properties of food and that AgRP neuron activity is positively reinforcing. These findings reveal that hunger neurons drive feeding by transmitting a positive valence signal that triggers a stable transition between behavioral states.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  2. Glucose Alters Per2 Rhythmicity Independent of AMPK, Whereas AMPK Inhibitor Compound C Causes Profound Repression of Clock Genes and AgRP in mHypoE-37 Hypothalamic Neurons

    PubMed Central

    Oosterman, Johanneke E.; Belsham, Denise D.

    2016-01-01

    Specific neurons in the hypothalamus are regulated by peripheral hormones and nutrients to maintain proper metabolic control. It is unclear if nutrients can directly control clock gene expression. We have therefore utilized the immortalized, hypothalamic cell line mHypoE-37, which exhibits robust circadian rhythms of core clock genes. mHypoE-37 neurons were exposed to 0.5 or 5.5 mM glucose, comparable to physiological levels in the brain. Per2 and Bmal1 mRNAs were assessed every 3 hours over 36 hours. Incubation with 5.5 mM glucose significantly shortened the period and delayed the phase of Per2 mRNA levels, but had no effect on Bmal1. Glucose had no significant effect on phospho-GSK3β, whereas AMPK phosphorylation was altered. Thus, the AMPK inhibitor Compound C was utilized, and mRNA levels of Per2, Bmal1, Cryptochrome1 (Cry1), agouti-related peptide (AgRP), carnitine palmitoyltransferase 1C (Cpt1c), and O-linked N-acetylglucosamine transferase (Ogt) were measured. Remarkably, Compound C dramatically reduced transcript levels of Per2, Bmal1, Cry1, and AgRP, but not Cpt1c or Ogt. Because AMPK was not inhibited at the same time or concentrations as the clock genes, we suggest that the effect of Compound C on gene expression occurs through an AMPK-independent mechanism. The consequences of inhibition of the rhythmic expression of clock genes, and in turn downstream metabolic mediators, such as AgRP, could have detrimental effects on overall metabolic processes. Importantly, the effects of the most commonly used AMPK inhibitor Compound C should be interpreted with caution, considering its role in AMPK-independent repression of specific genes, and especially clock gene rhythm dysregulation. PMID:26784927

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

    PubMed Central

    Xu, Yuanzhong; Shu, Gang; Wang, Chunmei; Yang, Yongjie; Saito, Kenji; Xu, Pingwen; Hinton, Antentor Othrell; Yan, Xiaofeng; Yu, Likai; Wu, Qi; Tso, Patrick; Tong, Qingchun; Xu, Yong

    2015-01-01

    Background/Aims Apolipoprotein A-IV (apoA-IV) in the brain potently suppresses food intake. However the mechanisms underlying its anorexigenic effects remain to be identified. Methods We first examined the effects of apoA-IV on cellular activities in hypothalamic neurons that co-express agouti-related peptide (AgRP) and neuropeptide Y (NPY) and in neurons that express pro-opiomelanocortin (POMC). We then compared anorexigenic effects of apoA-IV in wild type mice and in mutant mice lacking melanocortin 4 receptors (MC4Rs, the receptors of AgRP and the POMC gene product). Finally, we examined expression of apoA-IV in mouse hypothalamus and quantified its protein levels at fed vs. fasted states. Results We demonstrate that apoA-IV inhibited the firing rate of AgRP/NPY neurons. The decreased firing was associated with hyperpolarized membrane potential and decreased miniature excitatory postsynaptic current. We further used c-fos immunoreactivity to show that intracerebroventricular (i.c.v.) injections of apoA-IV abolished the fasting-induced activation of AgRP/NPY neurons in mice. Further, we found that apoA-IV depolarized POMC neurons and increased their firing rate. In addition, genetic deletion of MC4Rs blocked anorexigenic effects of i.c.v. apoA-IV. Finally, we detected endogenous apoA-IV in multiple neural populations in mouse hypothalamus, including AgRP/NPY neurons, and food deprivation suppresses hypothalamic apoA-IV protein levels. Conclusion Our findings support a model where central apoA-IV inhibits AgRP/NPY neurons and activates POMC neurons to activate MC4Rs, which in turn suppresses food intake. PMID:26337236

  4. AgRP Neural Circuits Mediate Adaptive Behaviors in the Starved State

    PubMed Central

    Padilla, Stephanie L.; Qiu, Jian; Soden, Marta E.; Sanz, Elisenda; Nestor, Casey C; Barker, Forrest D.; Quintana, Albert; Zweifel, Larry S.; Rønnekleiv, Oline K.; Kelly, Martin J.; Palmiter, Richard D.

    2016-01-01

    In the face of starvation animals will engage in high-risk behaviors that would normally be considered maladaptive. Starving rodents for example will forage in areas that are more susceptible to predators and will also modulate aggressive behavior within a territory of limited or depleted nutrients. The neural basis of these adaptive behaviors likely involves circuits that link innate feeding, aggression, and fear. Hypothalamic AgRP neurons are critically important for driving feeding and project axons to brain regions implicated in aggression and fear. Using circuit-mapping techniques, we define a disynaptic network originating from a subset of AgRP neurons that project to the medial nucleus of the amygdala and then to the principle bed nucleus of the stria terminalis, which plays a role in suppressing territorial aggression and reducing contextual fear. We propose that AgRP neurons serve as a master switch capable of coordinating behavioral decisions relative to internal state and environmental cues. PMID:27019015

  5. Neurons for hunger and thirst transmit a negative-valence teaching signal.

    PubMed

    Betley, J Nicholas; Xu, Shengjin; Cao, Zhen Fang Huang; Gong, Rong; Magnus, Christopher J; Yu, Yang; Sternson, Scott M

    2015-05-14

    Homeostasis is a biological principle for regulation of essential physiological parameters within a set range. Behavioural responses due to deviation from homeostasis are critical for survival, but motivational processes engaged by physiological need states are incompletely understood. We examined motivational characteristics of two separate neuron populations that regulate energy and fluid homeostasis by using cell-type-specific activity manipulations in mice. We found that starvation-sensitive AGRP neurons exhibit properties consistent with a negative-valence teaching signal. Mice avoided activation of AGRP neurons, indicating that AGRP neuron activity has negative valence. AGRP neuron inhibition conditioned preference for flavours and places. Correspondingly, deep-brain calcium imaging revealed that AGRP neuron activity rapidly reduced in response to food-related cues. Complementary experiments activating thirst-promoting neurons also conditioned avoidance. Therefore, these need-sensing neurons condition preference for environmental cues associated with nutrient or water ingestion, which is learned through reduction of negative-valence signals during restoration of homeostasis.

  6. Neurons for hunger and thirst transmit a negative-valence teaching signal

    PubMed Central

    Gong, Rong; Magnus, Christopher J.; Yu, Yang; Sternson, Scott M.

    2015-01-01

    Homeostasis is a biological principle for regulation of essential physiological parameters within a set range. Behavioural responses due to deviation from homeostasis are critical for survival, but motivational processes engaged by physiological need states are incompletely understood. We examined motivational characteristics and dynamics of two separate neuron populations that regulate energy and fluid homeostasis by using cell type-specific activity manipulations in mice. We found that starvation-sensitive AGRP neurons exhibit properties consistent with a negative-valence teaching signal. Mice avoided activation of AGRP neurons, indicating that AGRP neuron activity has negative valence. AGRP neuron inhibition conditioned preference for flavours and places. Correspondingly, deep-brain calcium imaging revealed that AGRP neuron activity rapidly reduced in response to food-related cues. Complementary experiments activating thirst-promoting neurons also conditioned avoidance. Therefore, these need-sensing neurons condition preference for environmental cues associated with nutrient or water ingestion, which is learned through reduction of negative-valence signals during restoration of homeostasis. PMID:25915020

  7. Hunger neurons drive feeding through a sustained, positive reinforcement signal

    PubMed Central

    Chen, Yiming; Lin, Yen-Chu; Zimmerman, Christopher A; Essner, Rachel A; Knight, Zachary A

    2016-01-01

    The neural mechanisms underlying hunger are poorly understood. AgRP neurons are activated by energy deficit and promote voracious food consumption, suggesting these cells may supply the fundamental hunger drive that motivates feeding. However recent in vivo recording experiments revealed that AgRP neurons are inhibited within seconds by the sensory detection of food, raising the question of how these cells can promote feeding at all. Here we resolve this paradox by showing that brief optogenetic stimulation of AgRP neurons before food availability promotes intense appetitive and consummatory behaviors that persist for tens of minutes in the absence of continued AgRP neuron activation. We show that these sustained behavioral responses are mediated by a long-lasting potentiation of the rewarding properties of food and that AgRP neuron activity is positively reinforcing. These findings reveal that hunger neurons drive feeding by transmitting a positive valence signal that triggers a stable transition between behavioral states. DOI: http://dx.doi.org/10.7554/eLife.18640.001 PMID:27554486

  8. Hypothalamic KLF4 mediates leptin's effects on food intake via AgRP.

    PubMed

    Imbernon, Monica; Sanchez-Rebordelo, Estrella; Gallego, Rosalia; Gandara, Marina; Lear, Pamela; Lopez, Miguel; Dieguez, Carlos; Nogueiras, Ruben

    2014-07-01

    Krüppel-like factor 4 (KLF4) is a zinc-finger-type transcription factor expressed in a range of tissues that plays multiple functions. We report that hypothalamic KLF4 represents a new transcription factor specifically modulating agouti-related protein (AgRP) expression in vivo. Hypothalamic KLF4 colocalizes with AgRP neurons and is modulated by nutritional status and leptin. Over-expression of KLF4 in the hypothalamic arcuate nucleus (ARC) induces food intake and increases body weight through the specific stimulation of AgRP, as well as blunting leptin sensitivity in lean rats independent of forkhead box protein 01 (FoxO1). Down-regulation of KLF4 in the ARC inhibits fasting-induced food intake in both lean and diet-induced obese (DIO) rats. Silencing KLF4, however, does not, on its own, enhance peripheral leptin sensitivity in DIO rats.

  9. Glucose sensing mechanisms in hypothalamic cell models: glucose inhibition of AgRP synthesis and secretion.

    PubMed

    Chalmers, Jennifer A; Jang, Janet J; Belsham, Denise D

    2014-01-25

    Glucose-sensing neurons play a role in energy homeostasis, yet how orexigenic neurons sense glucose remains unclear. As models of glucose-inhibited (GI) neurons, mHypoE-29/1 and mHypoA-NPY/GFP cells express the essential orexigenic neuropeptide AgRP and glucose sensing machinery. Exposure to increasing concentrations of glucose or the glucose analog 2-deoxyglucose (2-DG) results in a decrease in AgRP mRNA levels. Taste receptor, Tas1R2 mRNA expression was reduced by glucose, whereas 2-DG reduced Tas1R3 mRNA levels. Increasing glucose concentrations elicited a rise in Akt and neuronal nitric oxide synthase (nNOS) phosphorylation, CaMKKβ levels, and a reduction of AMP-kinase alpha phosphorylation. Inhibitors of NOS and the cystic fibrosis transmembrane conductance regulator (CFTR) prevented a decrease in AgRP secretion with glucose, suggesting a pivotal role for nNOS and the CFTR in glucose-sensing. These models possess the hallmark characteristics of GI neurons, and can be used to disentangle the mechanisms by which orexigenic neurons sense glucose.

  10. Energy Model of Neuron Activation.

    PubMed

    Romanyshyn, Yuriy; Smerdov, Andriy; Petrytska, Svitlana

    2017-02-01

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

  11. Making sense of the sensory regulation of hunger neurons.

    PubMed

    Chen, Yiming; Knight, Zachary A

    2016-04-01

    AgRP and POMC neurons are two key cell types that regulate feeding in response to hormones and nutrients. Recently, it was discovered that these neurons are also rapidly modulated by the mere sight and smell of food. This rapid sensory regulation "resets" the activity of AgRP and POMC neurons before a single bite of food has been consumed. This surprising and counterintuitive discovery challenges longstanding assumptions about the function and regulation of these cells. Here we review these recent findings and discuss their implications for our understanding of feeding behavior. We propose several alternative hypotheses for how these new observations might be integrated into a revised model of the feeding circuit, and also highlight some of the key questions that remain to be answered.

  12. The neuroendocrine circuitry controlled by POMC, MSH, and AGRP.

    PubMed

    Biebermann, Heike; Kühnen, Peter; Kleinau, Gunnar; Krude, Heiko

    2012-01-01

    Obesity is one of the most challenging health problems worldwide. Over the past few decades, our knowledge concerning mechanisms of weight regulation has increased tremendously leading to the identification of the leptin-melanocortin pathway. The filling level of energy stores is signaled to the brain, and the information is integrated by hypothalamic nuclei, resulting in a well-orchestrated response to food intake and energy expenditure to ensure constant body weight. One of the key players in this system is proopiomelanocortin (POMC), a precursor of a variety of neuropeptides. POMC-derived alpha- and beta-MSH play an important role in energy homeostasis by activating melanocortin receptors expressed in the arcuate nucleus (MC3R) and in the nucleus paraventricularis (MC4R). Activation of these two G protein-coupled receptors is antagonized by agouti-related peptide (AgRP). Naturally occurring mutations in this system were identified in patients suffering from common obesity as well as in patients demonstrating a phenotype of severe early-onset obesity, adrenal insufficiency, red hair, and pale skin. Detailed understanding of the complex system of POMC-AgRP-MC3R-MC4R and their interaction with other hypothalamic as well as peripheral signals is a prerequisite to combat the obesity epidemic.

  13. Cell type-specific transcriptomics of hypothalamic energy-sensing neuron responses to weight-loss.

    PubMed

    Henry, Fredrick E; Sugino, Ken; Tozer, Adam; Branco, Tiago; Sternson, Scott M

    2015-09-02

    Molecular and cellular processes in neurons are critical for sensing and responding to energy deficit states, such as during weight-loss. Agouti related protein (AGRP)-expressing neurons are a key hypothalamic population that is activated during energy deficit and increases appetite and weight-gain. Cell type-specific transcriptomics can be used to identify pathways that counteract weight-loss, and here we report high-quality gene expression profiles of AGRP neurons from well-fed and food-deprived young adult mice. For comparison, we also analyzed Proopiomelanocortin (POMC)-expressing neurons, an intermingled population that suppresses appetite and body weight. We find that AGRP neurons are considerably more sensitive to energy deficit than POMC neurons. Furthermore, we identify cell type-specific pathways involving endoplasmic reticulum-stress, circadian signaling, ion channels, neuropeptides, and receptors. Combined with methods to validate and manipulate these pathways, this resource greatly expands molecular insight into neuronal regulation of body weight, and may be useful for devising therapeutic strategies for obesity and eating disorders.

  14. Cell type-specific transcriptomics of hypothalamic energy-sensing neuron responses to weight-loss

    PubMed Central

    Henry, Fredrick E; Sugino, Ken; Tozer, Adam; Branco, Tiago; Sternson, Scott M

    2015-01-01

    Molecular and cellular processes in neurons are critical for sensing and responding to energy deficit states, such as during weight-loss. Agouti related protein (AGRP)-expressing neurons are a key hypothalamic population that is activated during energy deficit and increases appetite and weight-gain. Cell type-specific transcriptomics can be used to identify pathways that counteract weight-loss, and here we report high-quality gene expression profiles of AGRP neurons from well-fed and food-deprived young adult mice. For comparison, we also analyzed Proopiomelanocortin (POMC)-expressing neurons, an intermingled population that suppresses appetite and body weight. We find that AGRP neurons are considerably more sensitive to energy deficit than POMC neurons. Furthermore, we identify cell type-specific pathways involving endoplasmic reticulum-stress, circadian signaling, ion channels, neuropeptides, and receptors. Combined with methods to validate and manipulate these pathways, this resource greatly expands molecular insight into neuronal regulation of body weight, and may be useful for devising therapeutic strategies for obesity and eating disorders. DOI: http://dx.doi.org/10.7554/eLife.09800.001 PMID:26329458

  15. Active properties of neuronal dendrites.

    PubMed

    Johnston, D; Magee, J C; Colbert, C M; Cristie, B R

    1996-01-01

    Dendrites of neurons in the central nervous system are the principal sites for excitatory synaptic input. Although little is known about their function, two disparate perspectives have arisen to describe the activity patterns inherent to these diverse tree-like structures. Dendrites are thus considered either passive or active in their role in integrating synaptic inputs. This review follows the history of dendritic research from before the turn of the century to the present, with a primary focus on the hippocampus. A number of recent techniques, including high-speed fluorescence imaging and dendritic patch clamping, have provided new information and perspectives about the active properties of dendrites. The results support previous notions about the dendritic propagation of action potentials and also indicate which types of voltage-gated sodium and calcium channels are expressed and functionally active in dendrites. Possible roles for the active properties of dendrites in synaptic plasticity and integration are also discussed.

  16. Melanocortin 4 receptor constitutive activity inhibits L-type voltage-gated calcium channels in neurons.

    PubMed

    Agosti, F; Cordisco Gonzalez, S; Martinez Damonte, V; Tolosa, M J; Di Siervi, N; Schioth, H B; Davio, C; Perello, M; Raingo, J

    2017-03-27

    The melanocortin 4 receptor (MC4R) is a G protein-coupled receptor (GPCR) that is expressed in several brain nuclei playing a crucial role in the regulation of energy balance controlling the homeostasis of the organism. It displays both agonist-evoked and constitutive activity, and moreover, it can couple to different G proteins. Most of the research on MC4R has been focused on agonist-induced activity, while the molecular and cellular basis of MC4R constitutive activity remains scarcely studied. We have previously shown that neuronal N-type voltage-gated calcium channels (CaV2.2) are inhibited by MC4R agonist-dependent activation, while the CaV subtypes that carry L- and P/Q-type current are not. Here, we tested the hypothesis that MC4R constitutive activity can affect CaV, with focus on the channel subtypes that can control transcriptional activity coupled to depolarization (L-type, CaV1.2/1.3) and neurotransmitter release (N- and P/Q-type, CaV2.2 and CaV2.1). We found that MC4R constitutive activity inhibits specifically CaV1.2/1.3 and CaV2.1 subtypes of CaV. We also explored the signaling pathways mediating this inhibition, and thus propose that agonist-dependent and basal MC4R activation modes signal differentially through Gs and Gi/o pathways to impact on different CaV subtypes. In addition, we found that chronic incubation with MC4R endogenous inverse agonist, agouti and agouti-related peptide (AgRP), occludes CaV inhibition in a cell line and in amygdaloid complex cultured neurons as well. Thus, we define new mechanisms of control of the main mediators of depolarization-induced calcium entry into neurons by a GPCR that displays constitutive activity.

  17. Spontaneous Activity in Crustacean Neurons

    PubMed Central

    Preston, James B.; Kennedy, Donald

    1962-01-01

    Single units which discharged with regular spontaneous rhythms without intentional stimulation were observed in the ventral nerve cord by intracellular recording close to the sixth abdominal ganglion. These units were divided into two groups: group A units in which interspike intervals varied less than 10 msec.; group B units in which interspike intervals varied within a range of 10 to 30 msec. Group A units maintained "constant" interspike intervals and could not be discharged by sensory inputs, while the majority of group B units could be discharged by appropriate sensory nerve stimulation. Both group A and B units discharged to direct stimulation when the stimulating and recording electrodes were placed in the same ganglionic intersegment, and directly evoked single spikes reset the spontaneous rhythm. In group B units, presynaptic volleys reset the spontaneous rhythm of some units; but in others, synaptically evoked spikes were interpolated within the spontaneous rhythm without resetting. The phenomenon of enhancement could also be demonstrated in spontaneously active units as a result of repetitive stimulation. It is concluded that endogenous pacemaker activity is responsible for much of the regular spontaneous firing observed in crayfish central neurons, and that interaction of evoked responses with such pacemaker sites can produce a variety of effects dependent upon the anatomical relationships between pacemaker and synaptic regions. PMID:14488667

  18. Stiff substrates enhance cultured neuronal network activity.

    PubMed

    Zhang, Quan-You; Zhang, Yan-Yan; Xie, Jing; Li, Chen-Xu; Chen, Wei-Yi; Liu, Bai-Lin; Wu, Xiao-an; Li, Shu-Na; Huo, Bo; Jiang, Lin-Hua; Zhao, Hu-Cheng

    2014-08-28

    The mechanical property of extracellular matrix and cell-supporting substrates is known to modulate neuronal growth, differentiation, extension and branching. Here we show that substrate stiffness is an important microenvironmental cue, to which mouse hippocampal neurons respond and integrate into synapse formation and transmission in cultured neuronal network. Hippocampal neurons were cultured on polydimethylsiloxane substrates fabricated to have similar surface properties but a 10-fold difference in Young's modulus. Voltage-gated Ca(2+) channel currents determined by patch-clamp recording were greater in neurons on stiff substrates than on soft substrates. Ca(2+) oscillations in cultured neuronal network monitored using time-lapse single cell imaging increased in both amplitude and frequency among neurons on stiff substrates. Consistently, synaptic connectivity recorded by paired recording was enhanced between neurons on stiff substrates. Furthermore, spontaneous excitatory postsynaptic activity became greater and more frequent in neurons on stiff substrates. Evoked excitatory transmitter release and excitatory postsynaptic currents also were heightened at synapses between neurons on stiff substrates. Taken together, our results provide compelling evidence to show that substrate stiffness is an important biophysical factor modulating synapse connectivity and transmission in cultured hippocampal neuronal network. Such information is useful in designing instructive scaffolds or supporting substrates for neural tissue engineering.

  19. Subthalamic Nucleus Stimulation Modulates Thalamic Neuronal Activity

    PubMed Central

    Xu, Weidong; Russo, Gary S.; Hashimoto, Takao; Zhang, Jianyu; Vitek, Jerrold L.

    2009-01-01

    Deep brain stimulation (DBS) in the subthalamic nucleus (STN) is an effective tool for the treatment of advanced Parkinson’s disease. The mechanism by which STN DBS elicits its beneficial effect, however, remains unclear. We previously reported STN stimulation increased the rate and produced a more regular and periodic pattern of neuronal activity in the internal segment of the globus pallidus (GPi). Here we extend our observations to neurons in the pallidal (ventralis lateralis pars oralis (VLo) and ventralis anterior (VA)) and cerebellar (ventralis lateralis posterior pars oralis (VPLo)) receiving areas of the motor thalamus during STN DBS. Stimulation parameters that produced improvement in rigidity and bradykinesia resulted in changes in the pattern and power of oscillatory activity of neuronal activity that were similar in both regions of the motor thalamus. Neurons in both VA/VLo and VPLo tended to become more periodic and regular with a shift in oscillatory activity from low to high frequencies. Burst activity was reduced in VA/VLo, but was not significantly changed in VPLo. There was also a significant shift in the population of VA/VLo neurons that were inhibited during STN DBS, while VPLo neurons tended to be activated. These data are consistent with the hypothesis that STN DBS increases output from the nucleus and produces a change in the pattern and periodicity of neuronal activity in the basal ganglia thalamic network, and that these changes include cerebellar pathways likely via activation of adjacent cerebello-thalamic fiber bundles. PMID:19005057

  20. PDK1-Foxo1 in Agouti-Related Peptide Neurons Regulates Energy Homeostasis by Modulating Food Intake and Energy Expenditure

    PubMed Central

    Cao, Yongheng; Nakata, Masanori; Okamoto, Shiki; Takano, Eisuke; Yada, Toshihiko; Minokoshi, Yasuhiko; Hirata, Yukio; Nakajima, Kazunori; Iskandar, Kristy; Hayashi, Yoshitake; Ogawa, Wataru; Barsh, Gregory S.; Hosoda, Hiroshi; Kangawa, Kenji; Itoh, Hiroshi; Noda, Tetsuo; Kasuga, Masato; Nakae, Jun

    2011-01-01

    Insulin and leptin intracellular signaling pathways converge and act synergistically on the hypothalamic phosphatidylinositol-3-OH kinase/3-phosphoinositide-dependent protein kinase 1 (PDK1). However, little is known about whether PDK1 in agouti-related peptide (AGRP) neurons contributes to energy homeostasis. We generated AGRP neuron-specific PDK1 knockout (AGRPPdk1−/−) mice and mice with selective expression of transactivation-defective Foxo1 (Δ256Foxo1AGRPPdk1−/−). The AGRPPdk1−/− mice showed reductions in food intake, body length, and body weight. The Δ256Foxo1AGRPPdk1−/− mice showed increased body weight, food intake, and reduced locomotor activity. After four weeks of calorie-restricted feeding, oxygen consumption and locomotor activity were elevated in AGRPPdk1−/− mice and reduced in Δ256Foxo1AGRPPdk1−/− mice. In vitro, ghrelin-induced changes in [Ca2+]i and inhibition of ghrelin by leptin were significantly attenuated in AGRPPdk1−/− neurons compared to control neurons. However, ghrelin-induced [Ca2+]i changes and leptin inhibition were restored in Δ256Foxo1AGRPPdk1−/− mice. These results suggested that PDK1 and Foxo1 signaling pathways play important roles in the control of energy homeostasis through AGRP-independent mechanisms. PMID:21694754

  1. Sloppiness in spontaneously active neuronal networks.

    PubMed

    Panas, Dagmara; Amin, Hayder; Maccione, Alessandro; Muthmann, Oliver; van Rossum, Mark; Berdondini, Luca; Hennig, Matthias H

    2015-06-03

    Various plasticity mechanisms, including experience-dependent, spontaneous, as well as homeostatic ones, continuously remodel neural circuits. Yet, despite fluctuations in the properties of single neurons and synapses, the behavior and function of neuronal assemblies are generally found to be very stable over time. This raises the important question of how plasticity is coordinated across the network. To address this, we investigated the stability of network activity in cultured rat hippocampal neurons recorded with high-density multielectrode arrays over several days. We used parametric models to characterize multineuron activity patterns and analyzed their sensitivity to changes. We found that the models exhibited sloppiness, a property where the model behavior is insensitive to changes in many parameter combinations, but very sensitive to a few. The activity of neurons with sloppy parameters showed faster and larger fluctuations than the activity of a small subset of neurons associated with sensitive parameters. Furthermore, parameter sensitivity was highly correlated with firing rates. Finally, we tested our observations from cell cultures on an in vivo recording from monkey visual cortex and we confirm that spontaneous cortical activity also shows hallmarks of sloppy behavior and firing rate dependence. Our findings suggest that a small subnetwork of highly active and stable neurons supports group stability, and that this endows neuronal networks with the flexibility to continuously remodel without compromising stability and function.

  2. Activity-Dependent Model for Neuronal Avalanches

    NASA Astrophysics Data System (ADS)

    de Arcangelis, L.

    Networks of living neurons represent one of the most fascinating systems of modern biology. If the physical and chemical mechanisms at the basis of the functioning of a single neuron are quite well understood, the collective behavior of a system of many neurons is an extremely intriguing subject. Crucial ingredient of this complex behavior is the plasticity property of the network, namely the capacity to adapt and evolve depending on the level of activity. This plastic ability is believed, nowadays, to be at the basis of learning and memory in real brains. This fundamental problem in neurobiology has recently shown a number of features in common to other complex systems. These features mainly concern the morphology of the network, namely the spatial organization of the established connections, and a novel kind of neuronal activity. Experimental data have, in fact, shown that electrical information propagates in a cortex slice via an avalanche mode. Both features have been found in other problems in the context of the physics of complex systems and successful models have been developed to describe their behavior. In this contribution, we apply a statistical mechanical model to describe the complex activity in a neuronal network. The network is chosen to have a number of connections in long range, as found for neurons in vitro. The model implements the main physiological properties of living neurons and is able to reproduce recent experimental results. The numerical power spectra for electrical activity reproduces also the power law behavior measured in an EEG of man resting with the eyes closed.

  3. Neuronal avalanches in spontaneous activity in vivo.

    PubMed

    Hahn, Gerald; Petermann, Thomas; Havenith, Martha N; Yu, Shan; Singer, Wolf; Plenz, Dietmar; Nikolic, Danko

    2010-12-01

    Many complex systems give rise to events that are clustered in space and time, thereby establishing a correlation structure that is governed by power law statistics. In the cortex, such clusters of activity, called "neuronal avalanches," were recently found in local field potentials (LFPs) of spontaneous activity in acute cortex slices, slice cultures, the developing cortex of the anesthetized rat, and premotor and motor cortex of awake monkeys. At present, it is unclear whether neuronal avalanches also exist in the spontaneous LFPs and spike activity in vivo in sensory areas of the mature brain. To address this question, we recorded spontaneous LFPs and extracellular spiking activity with multiple 4 × 4 microelectrode arrays (Michigan Probes) in area 17 of adult cats under anesthesia. A cluster of events was defined as a consecutive sequence of time bins Δt (1-32 ms), each containing at least one LFP event or spike anywhere on the array. LFP cluster sizes consistently distributed according to a power law with a slope largely above -1.5. In two thirds of the corresponding experiments, spike clusters also displayed a power law that displayed a slightly steeper slope of -1.8 and was destroyed by subsampling operations. The power law in spike clusters was accompanied with stronger temporal correlations between spiking activities of neurons that spanned longer time periods compared with spike clusters lacking power law statistics. The results suggest that spontaneous activity of the visual cortex under anesthesia has the properties of neuronal avalanches.

  4. Lipoprotein Lipase is an Important Modulator of Lipid Uptake and Storage in Hypothalamic Neurons

    PubMed Central

    Libby, Andrew E.; Wang, Hong; Mittal, Richa; Sungelo, Mitchell; Potma, Eric; Eckel, Robert H.

    2015-01-01

    LPL is the rate-limiting enzyme for uptake of TG-derived FFA in peripheral tissues, and the enzyme is expressed in the brain and CNS. We previously created a mouse which lacks neuronal LPL. This animal becomes obese on a standard chow, and we observed reduced lipid uptake in the hypothalamus at 3 months preceding obesity. In our present study, we replicated the animal phenotype in an immortalized mouse hypothalamic cell line (N41) to examine how LPL affects expression of AgRP as well as entry and storage of lipids into neurons. We show that LPL is able to modulate levels of the orexigenic peptide AgRP. LPL also exerts effects on lipid uptake into culture neurons, and that uptake of neutral lipid can be enhanced even by mutant LPL lacking catalytic activity. N41 cells also accumulate neutral lipid in droplets, and this is at least in part regulated by LPL. These data in addition to those published in mice with neuron-specific deletion of LPL suggest that neuronal LPL is an important regulator of lipid homeostasis in neurons and that alterations in LPL levels may have important effects on systemic metabolism and neuronal lipid biology. PMID:26265042

  5. Which Neurons Will Be the Engram - Activated Neurons and/or More Excitable Neurons?

    PubMed Central

    Kim, Ji-il; Cho, Hye-Yeon; Han, Jin-Hee

    2016-01-01

    During past decades, the formation and storage principle of memory have received much attention in the neuroscience field. Although some studies have attempted to demonstrate the nature of the engram, elucidating the memory engram allocation mechanism was not possible because of the limitations of existing methods, which cannot specifically modulate the candidate neuronal population. Recently, the development of new techniques, which offer ways to mark and control specific populations of neurons, may accelerate solving this issue. Here, we review the recent advances, which have provided substantial evidence showing that both candidates (neuronal population that is activated by learning, and that has increased CREB level/excitability at learning) satisfy the criteria of the engram, which are necessary and sufficient for memory expression. PMID:27122991

  6. Peroxisome proliferator-activated receptor γ controls ingestive behavior, agouti-related protein, and neuropeptide Y mRNA in the arcuate hypothalamus.

    PubMed

    Garretson, John T; Teubner, Brett J W; Grove, Kevin L; Vazdarjanova, Almira; Ryu, Vitaly; Bartness, Timothy J

    2015-03-18

    Peroxisome proliferator-activated receptor γ (PPARγ) is clinically targeted for type II diabetes treatment; however, rosiglitazone (ROSI), a PPARγ agonist, increases food intake and body/fat mass as side-effects. Mechanisms for these effects and the role of PPARγ in feeding are not understood. Therefore, we tested this role in Siberian hamsters, a model of human energy balance, and C57BL/6 mice. We tested the following: (1) how ROSI and/or GW9662 (2-chloro-5-nitro-N-phenylbenzamide; PPARγ antagonist) injected intraperitoneally or into the third ventricle (3V) affected Siberian hamster feeding behaviors; (2) whether food deprivation (FD) co-increases agouti-related protein (AgRP) and PPARγ mRNA expression in Siberian hamsters and mice; (3) whether intraperitoneally administered ROSI increases AgRP and NPY in ad libitum-fed animals; (4) whether intraperitoneally administered PPARγ antagonism blocks FD-induced increases in AgRP and NPY; and finally, (5) whether intraperitoneally administered PPARγ modulation affects plasma ghrelin. Third ventricular and intraperitoneally administered ROSI increased food hoarding and intake for 7 d, an effect attenuated by 3V GW9662, and also prevented (intraperitoneal) FD-induced feeding. FD hamsters and mice increased AgRP within the arcuate hypothalamic nucleus with concomitant increases in PPARγ exclusively within AgRP/NPY neurons. ROSI increased AgRP and NPY similarly to FD, and GW9662 prevented FD-induced increases in AgRP and NPY in both species. Neither ROSI nor GW9662 affected plasma ghrelin. Thus, we demonstrated that PPARγ activation is sufficient to trigger food hoarding/intake, increase AgRP/NPY, and possibly is necessary for FD-induced increases in feeding and AgRP/NPY. These findings provide initial evidence that FD-induced increases in AgRP/NPY may be a direct PPARγ-dependent process that controls ingestive behaviors.

  7. Active Dendrites Enhance Neuronal Dynamic Range

    PubMed Central

    Gollo, Leonardo L.; Kinouchi, Osame; Copelli, Mauro

    2009-01-01

    Since the first experimental evidences of active conductances in dendrites, most neurons have been shown to exhibit dendritic excitability through the expression of a variety of voltage-gated ion channels. However, despite experimental and theoretical efforts undertaken in the past decades, the role of this excitability for some kind of dendritic computation has remained elusive. Here we show that, owing to very general properties of excitable media, the average output of a model of an active dendritic tree is a highly non-linear function of its afferent rate, attaining extremely large dynamic ranges (above 50 dB). Moreover, the model yields double-sigmoid response functions as experimentally observed in retinal ganglion cells. We claim that enhancement of dynamic range is the primary functional role of active dendritic conductances. We predict that neurons with larger dendritic trees should have larger dynamic range and that blocking of active conductances should lead to a decrease in dynamic range. PMID:19521531

  8. Heparin activates Wnt signaling for neuronal morphogenesis.

    PubMed

    Colombres, Marcela; Henríquez, Juan Pablo; Reig, Germán F; Scheu, Jessica; Calderón, Rosario; Alvarez, Alejandra; Brandan, Enrique; Inestrosa, Nibaldo C

    2008-09-01

    Wnt factors are secreted ligands that affect different aspects of the nervous system behavior like neurodevelopment, synaptogenesis and neurodegeneration. In different model systems, Wnt signaling has been demonstrated to be regulated by heparan sulfate proteoglycans (HSPGs). Whether HSPGs modulate Wnt signaling in the context of neuronal behavior is currently unknown. Here we demonstrate that activation of Wnt signaling with the endogenous ligand Wnt-7a results in an increased of neurite outgrowth in the neuroblastoma N2a cell line. Interestingly, heparin induces glycogen synthase kinase-3beta (GSK-3beta) inhibition, beta-catenin stabilization and morphological differentiation in both N2a cells and in rat primary hippocampal neuronal cultures. We also show that heparin modulates Wnt-3a-induced stabilization of beta-catenin. Several extracellular matrix and membrane-attached HSPGs were found to be expressed in both in vitro neuronal models. Changes in the expression of specific HSPGs were observed upon differentiation of N2a cells. Taken together, our findings suggest that HSPGs may modulate canonical Wnt signaling for neuronal morphogenesis.

  9. Linoleic acid and stearic acid elicit opposite effects on AgRP expression and secretion via TLR4-dependent signaling pathways in immortalized hypothalamic N38 cells.

    PubMed

    Wang, Songbo; Xiang, Nana; Yang, Liusong; Zhu, Canjun; Zhu, Xiaotong; Wang, Lina; Gao, Ping; Xi, Qianyun; Zhang, Yongliang; Shu, Gang; Jiang, Qingyan

    2016-03-18

    The regulation of food intake is a promising way to combat obesity. It has been implicated that various fatty acids exert different effects on food intake and body weight. However, the underlying mechanism remains poorly understood. The aim of the present study was to investigate the effects of linoleic acid (LA) and stearic acid (SA) on agouti-related protein (AgRP) expression and secretion in immortalized mouse hypothalamic N38 cells and to explore the likely underlying mechanisms. Our results demonstrated that LA inhibited, while SA stimulated AgRP expression and secretion of N38 cells in a dose-dependent manner. In addition, LA suppressed the protein expression of toll-like receptor 4 (TLR4), phosphorylation levels of JNK and IKKα/β, suggesting the inhibition of TLR4-dependent inflammation pathway. However, the above mentioned inhibitory effects of LA were eliminated by TLR4 agonist lipopolysaccharide (LPS). In contrast, SA promoted TLR4 protein expression and activated TLR4-dependent inflammation pathway, with elevated ratio of p-JNK/JNK. While TLR4 siRNA reversed the stimulatory effects of SA on AgRP expression and TLR4-dependent inflammation. Moreover, we found that TLR4 was also involved in LA-enhanced and SA-impaired leptin/insulin signal pathways in N38 cells. In conclusion, our findings indicated that LA elicited inhibitory while SA exerted stimulatory effects on AgRP expression and secretion via TLR4-dependent inflammation and leptin/insulin pathways in N38 cells. These data provided a better understanding of the mechanism underlying fatty acids-regulated food intake and suggested the potential role of long-chain unsaturated fatty acids such as LA in reducing food intake and treating obesity.

  10. Melanocortin 4 receptor ligands modulate energy homeostasis through urocortin 1 neurons of the centrally projecting Edinger-Westphal nucleus.

    PubMed

    Füredi, Nóra; Nagy, Ákos; Mikó, Alexandra; Berta, Gergely; Kozicz, Tamás; Pétervári, Erika; Balaskó, Márta; Gaszner, Balázs

    2017-03-03

    The role of the urocortin 1 (Ucn1) expressing centrally projecting Edinger-Westphal (EWcp) nucleus in energy homeostasis and stress adaptation response has previously been investigated. Morphological and functional studies have proven that orexigenic and anorexigenic peptidergic afferents and receptors for endocrine messengers involved in the energy homeostasis are found in the EWcp. The central role of the hypothalamic melanocortin system in energy homeostasis is well known, however, no data have been published so far on possible crosstalk between melanocortins and EWcp-Ucn1. First, we hypothesized that members of the melanocortin system [i.e. alpha-melanocyte stimulating hormone (alpha-MSH), agouti-related peptide (AgRP), melanocortin 4 receptor (MC4R)] would be expressed in the EWcp. Second, we put forward, that alpha-MSH and AgRP contents as well as neuronal activity and Ucn1 peptide content of the EWcp would be affected by fasting. Third, we assumed that the intra-EWcp injections of exogenous MC4R agonists and antagonist would cause food intake-related and metabolic changes. Ucn1 neurons were found to carry MC4Rs, and they were contacted both by alpha-MSH and AgRP immunoreactive nerve fibers in the rat. The alpha-MSH immunosignal was reduced, while that of AgRP was increased upon starvation. These were associated with the elevation of FosB and Ucn1 expression. The intra-EWcp administration of MC4R blocker (i.e. HS024) had a similar, but enhanced effect on FosB and Ucn1. Furthermore, alpha-MSH injected into the EWcp had anorexigenic effect, increased oxygen consumption and caused peripheral vasodilation. We conclude that the melanocortin system influences the EWcp that contributes to energy-homeostasis.

  11. New photochemical tools for controlling neuronal activity

    PubMed Central

    Kramer, Richard H.; Fortin, Doris L.; Trauner, Dirk

    2009-01-01

    Neurobiology has entered a new era in which optical methods are challenging electrophysiological techniques for their value in measuring and manipulating neuronal activity. This change is occurring largely because of the development of new photochemical tools, some synthesized by chemists and some provided by nature. This review is focused on the three types of photochemical tools for neuronal control that have emerged in recent years. Caged neurotransmitters, including caged glutamate, are synthetic molecules that enable highly localized activation of neurotransmitter receptors in response to light. Natural photosensitive proteins, including channelrhodopsin-2 and halorhodopsin, can be exogenously expressed in neurons and enable rapid photocontrol of action potential firing. Synthetic small-molecule photoswitches can bestow light-sensitivity on native or exogenously expressed proteins, including K+ channels and glutamate receptors, allowing photocontrol of action potential firing and synaptic events. At a rapid pace, these tools are being improved and new tools are being introduced, thanks to molecular biology and synthetic chemistry. The three families of photochemical tools have different capabilities and uses, but they all share in enabling precise and non-invasive exploration of neural function with light. PMID:19828309

  12. A robust activity marking system for exploring active neuronal ensembles.

    PubMed

    Sørensen, Andreas T; Cooper, Yonatan A; Baratta, Michael V; Weng, Feng-Ju; Zhang, Yuxiang; Ramamoorthi, Kartik; Fropf, Robin; LaVerriere, Emily; Xue, Jian; Young, Andrew; Schneider, Colleen; Gøtzsche, Casper René; Hemberg, Martin; Yin, Jerry Cp; Maier, Steven F; Lin, Yingxi

    2016-09-23

    Understanding how the brain captures transient experience and converts it into long lasting changes in neural circuits requires the identification and investigation of the specific ensembles of neurons that are responsible for the encoding of each experience. We have developed a Robust Activity Marking (RAM) system that allows for the identification and interrogation of ensembles of neurons. The RAM system provides unprecedented high sensitivity and selectivity through the use of an optimized synthetic activity-regulated promoter that is strongly induced by neuronal activity and a modified Tet-Off system that achieves improved temporal control. Due to its compact design, RAM can be packaged into a single adeno-associated virus (AAV), providing great versatility and ease of use, including application to mice, rats, flies, and potentially many other species. Cre-dependent RAM, CRAM, allows for the study of active ensembles of a specific cell type and anatomical connectivity, further expanding the RAM system's versatility.

  13. Pharmacogenetic activation of midbrain dopaminergic neurons induces hyperactivity.

    PubMed

    Wang, Shujie; Tan, Yan; Zhang, Ju-En; Luo, Minmin

    2013-10-01

    Dopaminergic neurons regulate and organize numerous important behavioral processes including motor activity. Consistently, manipulation of brain dopamine concentrations changes animal activity levels. Dopamine is synthesized by several neuronal populations in the brain. This study was carried out to directly test whether selective activation of dopamine neurons in the midbrain induces hyperactivity. A pharmacogenetic approach was used to activate midbrain dopamine neurons, and behavioral assays were conducted to determine the effects on mouse activity levels. Transgenic expression of the evolved hM3Dq receptor was achieved by infusing Cre-inducible AAV viral vectors into the midbrain of DAT-Cre mice. Neurons were excited by injecting the hM3Dq ligand clozapine-N-oxide (CNO). Mouse locomotor activity was measured in an open field. The results showed that CNO selectively activated midbrain dopaminergic neurons and induced hyperactivity in a dose-dependent manner, supporting the idea that these neurons play an important role in regulating motor activity.

  14. Arcuate Na+,K+-ATPase senses systemic energy states and regulates feeding behavior through glucose-inhibited neurons.

    PubMed

    Kurita, Hideharu; Xu, Kai Y; Maejima, Yuko; Nakata, Masanori; Dezaki, Katsuya; Santoso, Putra; Yang, Yifei; Arai, Takeshi; Gantulga, Darambazar; Muroya, Shinji; Lefor, Alan K; Kakei, Masafumi; Watanabe, Eiju; Yada, Toshihiko

    2015-08-15

    Feeding is regulated by perception in the hypothalamus, particularly the first-order arcuate nucleus (ARC) neurons, of the body's energy state. However, the cellular device for converting energy states to the activity of critical neurons in ARC is less defined. We here show that Na(+),K(+)-ATPase (NKA) in ARC senses energy states to regulate feeding. Fasting-induced systemic ghrelin rise and glucose lowering reduced ATP-hydrolyzing activity of NKA and its substrate ATP level, respectively, preferentially in ARC. Lowering glucose concentration (LG), which mimics fasting, decreased intracellular NAD(P)H and increased Na(+) concentration in single ARC neurons that subsequently exhibited [Ca(2+)]i responses to LG, showing that they were glucose-inhibited (GI) neurons. Third ventricular injection of the NKA inhibitor ouabain induced c-Fos expression in agouti-related protein (AgRP) neurons in ARC and evoked neuropeptide Y (NPY)-dependent feeding. When injected focally into ARC, ouabain stimulated feeding and mRNA expressions for NPY and AgRP. Ouabain increased [Ca(2+)]i in single NPY/AgRP neurons with greater amplitude than in proopiomelanocortin neurons in ARC. Conversely, the specific NKA activator SSA412 suppressed fasting-induced feeding and LG-induced [Ca(2+)]i increases in ARC GI neurons. NPY/AgRP neurons highly expressed NKAα3, whose knockdown impaired feeding behavior. These results demonstrate that fasting, via ghrelin rise and LG, suppresses NKA enzyme/pump activity in ARC and thereby promotes the activation of GI neurons and NPY/AgRP-dependent feeding. This study identifies ARC NKA as a hypothalamic sensor and converter of metabolic states to key neuronal activity and feeding behaviour, providing a new target to treat hyperphagic obesity and diabetes.

  15. [Transformation of neuronal activity in the cat lateral geniculate body].

    PubMed

    Silakov, V L

    1976-05-01

    The neuronal activity transformations were studied in the cat LGB under the action of nembutal, light stimulation, and micropolarization of geniculate cells. The transformation of single spike activity into bursts was found to reflect the inhibitory state of the neurons. Their excitation entailed a reverse transformation. Short feed-back connections functioning within the microsystems of LGB neurons are supposed to underlie the transformations.

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

    SciTech Connect

    Born, D.E.

    1986-01-01

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

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

    PubMed

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

    2016-03-16

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

  18. Human Cerebrospinal Fluid Promotes Neuronal Viability and Activity of Hippocampal Neuronal Circuits In Vitro

    PubMed Central

    Perez-Alcazar, Marta; Culley, Georgia; Lyckenvik, Tim; Mobarrez, Kristoffer; Bjorefeldt, Andreas; Wasling, Pontus; Seth, Henrik; Asztely, Frederik; Harrer, Andrea; Iglseder, Bernhard; Aigner, Ludwig; Hanse, Eric; Illes, Sebastian

    2016-01-01

    For decades it has been hypothesized that molecules within the cerebrospinal fluid (CSF) diffuse into the brain parenchyma and influence the function of neurons. However, the functional consequences of CSF on neuronal circuits are largely unexplored and unknown. A major reason for this is the absence of appropriate neuronal in vitro model systems, and it is uncertain if neurons cultured in pure CSF survive and preserve electrophysiological functionality in vitro. In this article, we present an approach to address how human CSF (hCSF) influences neuronal circuits in vitro. We validate our approach by comparing the morphology, viability, and electrophysiological function of single neurons and at the network level in rat organotypic slice and primary neuronal cultures cultivated either in hCSF or in defined standard culture media. Our results demonstrate that rodent hippocampal slices and primary neurons cultured in hCSF maintain neuronal morphology and preserve synaptic transmission. Importantly, we show that hCSF increases neuronal viability and the number of electrophysiologically active neurons in comparison to the culture media. In summary, our data indicate that hCSF represents a physiological environment for neurons in vitro and a superior culture condition compared to the defined standard media. Moreover, this experimental approach paves the way to assess the functional consequences of CSF on neuronal circuits as well as suggesting a novel strategy for central nervous system (CNS) disease modeling. PMID:26973467

  19. Invisible Brain: Knowledge in Research Works and Neuron Activity

    PubMed Central

    Segev, Aviv; Curtis, Dorothy; Jung, Sukhwan; Chae, Suhyun

    2016-01-01

    If the market has an invisible hand, does knowledge creation and representation have an “invisible brain”? While knowledge is viewed as a product of neuron activity in the brain, can we identify knowledge that is outside the brain but reflects the activity of neurons in the brain? This work suggests that the patterns of neuron activity in the brain can be seen in the representation of knowledge-related activity. Here we show that the neuron activity mechanism seems to represent much of the knowledge learned in the past decades based on published articles, in what can be viewed as an “invisible brain” or collective hidden neural networks. Similar results appear when analyzing knowledge activity in patents. Our work also tries to characterize knowledge increase as neuron network activity growth. The results propose that knowledge-related activity can be seen outside of the neuron activity mechanism. Consequently, knowledge might exist as an independent mechanism. PMID:27439199

  20. Human embryonic stem cell-derived neuronal cells form spontaneously active neuronal networks in vitro.

    PubMed

    Heikkilä, Teemu J; Ylä-Outinen, Laura; Tanskanen, Jarno M A; Lappalainen, Riikka S; Skottman, Heli; Suuronen, Riitta; Mikkonen, Jarno E; Hyttinen, Jari A K; Narkilahti, Susanna

    2009-07-01

    The production of functional human embryonic stem cell (hESC)-derived neuronal cells is critical for the application of hESCs in treating neurodegenerative disorders. To study the potential functionality of hESC-derived neurons, we cultured and monitored the development of hESC-derived neuronal networks on microelectrode arrays. Immunocytochemical studies revealed that these networks were positive for the neuronal marker proteins beta-tubulin(III) and microtubule-associated protein 2 (MAP-2). The hESC-derived neuronal networks were spontaneously active and exhibited a multitude of electrical impulse firing patterns. Synchronous bursts of electrical activity similar to those reported for hippocampal neurons and rodent embryonic stem cell-derived neuronal networks were recorded from the differentiated cultures until up to 4 months. The dependence of the observed neuronal network activity on sodium ion channels was examined using tetrodotoxin (TTX). Antagonists for the glutamate receptors NMDA [D(-)-2-amino-5-phosphonopentanoic acid] and AMPA/kainate [6-cyano-7-nitroquinoxaline-2,3-dione], and for GABAA receptors [(-)-bicuculline methiodide] modulated the spontaneous electrical activity, indicating that pharmacologically susceptible neuronal networks with functional synapses had been generated. The findings indicate that hESC-derived neuronal cells can generate spontaneously active networks with synchronous communication in vitro, and are therefore suitable for use in developmental and drug screening studies, as well as for regenerative medicine.

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

    PubMed

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

    2013-04-10

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

  2. Prediction of primary somatosensory neuron activity during active tactile exploration

    PubMed Central

    Campagner, Dario; Evans, Mathew Hywel; Bale, Michael Ross; Erskine, Andrew; Petersen, Rasmus Strange

    2016-01-01

    Primary sensory neurons form the interface between world and brain. Their function is well-understood during passive stimulation but, under natural behaving conditions, sense organs are under active, motor control. In an attempt to predict primary neuron firing under natural conditions of sensorimotor integration, we recorded from primary mechanosensory neurons of awake, head-fixed mice as they explored a pole with their whiskers, and simultaneously measured both whisker motion and forces with high-speed videography. Using Generalised Linear Models, we found that primary neuron responses were poorly predicted by whisker angle, but well-predicted by rotational forces acting on the whisker: both during touch and free-air whisker motion. These results are in apparent contrast to previous studies of passive stimulation, but could be reconciled by differences in the kinematics-force relationship between active and passive conditions. Thus, simple statistical models can predict rich neural activity elicited by natural, exploratory behaviour involving active movement of sense organs. DOI: http://dx.doi.org/10.7554/eLife.10696.001 PMID:26880559

  3. Involvement of dopaminergic neuronal cystatin C in neuronal injury-induced microglial activation and neurotoxicity.

    PubMed

    Dutta, Garima; Barber, David S; Zhang, Ping; Doperalski, Nicholas J; Liu, Bin

    2012-08-01

    Factors released from injured dopaminergic (DA) neurons may trigger microglial activation and set in motion a vicious cycle of neuronal injury and inflammation that fuels progressive DA neurodegeneration in Parkinson's disease. In this study, using proteomic and immunoblotting analysis, we detected elevated levels of cystatin C in conditioned media (CM) from 1-methyl-4-phenylpyridinium and dieldrin-injured rat DA neuronal cells. Immunodepletion of cystatin C significantly reduced the ability of DA neuronal CM to induce activation of rat microglial cells as determined by up-regulation of inducible nitric oxide synthase, production of free radicals and release of proinflammatory cytokines as well as activated microglia-mediated DA neurotoxicity. Treatment of the cystatin C-containing CM with enzymes that remove O- and sialic acid-, but not N-linked carbohydrate moieties markedly reduced the ability of the DA neuronal CM to activate microglia. Taken together, these results suggest that DA neuronal cystatin C plays a role in the neuronal injury-induced microglial activation and neurotoxicity. These findings from the rat DA neuron-microglia in vitro model may help guide continued investigation to define the precise role of cystatin C in the complex interplay among neurons and glia in the pathogenesis of Parkinson's disease.

  4. Central Amygdala Somatostatin Neurons Gate Passive and Active Defensive Behaviors

    PubMed Central

    Yu, Kai; Garcia da Silva, Pedro; Albeanu, Dinu F.

    2016-01-01

    The central amygdala (CeA) has a key role in learning and expression of defensive responses. Recent studies indicate that somatostatin-expressing (SOM+) neurons in the lateral division of the CeA (CeL) are essential for the acquisition and recall of conditioned freezing behavior, which has been used as an index of defensive response in laboratory animals during Pavlovian fear conditioning. However, how exactly these neurons participate in fear conditioning and whether they contribute to the generation of defensive responses other than freezing remain unknown. Here, using fiber-optic photometry combined with optogenetic and molecular techniques in behaving mice, we show that SOM+ CeL neurons are activated by threat-predicting sensory cues after fear conditioning and that activation of these neurons suppresses ongoing actions and converts an active defensive behavior to a passive response. Furthermore, inhibition of these neurons using optogenetic or molecular methods promotes active defensive behaviors. Our results provide the first in vivo evidence that SOM+ neurons represent a CeL population that acquires learning-dependent sensory responsiveness during fear conditioning and furthermore reveal an important role of these neurons in gating passive versus active defensive behaviors in animals confronted with threat. SIGNIFICANCE STATEMENT The ability to develop adaptive behavioral responses to threat is fundamental for survival. Recent studies indicate that the central lateral amygdala (CeL), in particular its somatostatin-expressing neurons, is crucial for both learning and the expression of defensive response. However, how exactly these neurons participate in such processes remains unclear. Here we show for the first time in behaving mice that the somatostatin-expressing neurons in the CeL acquire learning-dependent responsiveness to sensory cues predicting a threat. Furthermore, our results indicate that these neurons gate the behavioral output of an animal

  5. Circadian rhythms in neuronal activity propagate through output circuits

    PubMed Central

    Cavey, Matthieu; Collins, Ben; Bertet, Claire; Blau, Justin

    2016-01-01

    24hr rhythms in behavior are organized by a network of circadian pacemaker neurons. Rhythmic activity in this network is generated by intrinsic rhythms in clock neuron physiology and communication between clock neurons. However, it is poorly understood how the activity of a small number of pacemaker neurons is translated into rhythmic behavior of the whole animal. To understand this, we screened for signals that could identify circadian output circuits in Drosophila. We found that Leucokinin neuropeptide (LK) and its receptor (LK-R) are required for normal behavioral rhythms. This LK/LK-R circuit connects pacemaker neurons to brain areas that regulate locomotor activity and sleep. Our experiments revealed that pacemaker neurons impose rhythmic activity and excitability on LK and LK-R expressing neurons. We also found pacemaker neuron-dependent activity rhythms in DH44-expressing neurons, a second circadian output pathway. We conclude that rhythmic clock neuron activity propagates to multiple downstream circuits to orchestrate behavioral rhythms. PMID:26928065

  6. Circadian rhythms in neuronal activity propagate through output circuits.

    PubMed

    Cavey, Matthieu; Collins, Ben; Bertet, Claire; Blau, Justin

    2016-04-01

    Twenty-four hour rhythms in behavior are organized by a network of circadian pacemaker neurons. Rhythmic activity in this network is generated by intrinsic rhythms in clock neuron physiology and communication between clock neurons. However, it is poorly understood how the activity of a small number of pacemaker neurons is translated into rhythmic behavior of the whole animal. To understand this, we screened for signals that could identify circadian output circuits in Drosophila melanogaster. We found that leucokinin neuropeptide (LK) and its receptor (LK-R) were required for normal behavioral rhythms. This LK/LK-R circuit connects pacemaker neurons to brain areas that regulate locomotor activity and sleep. Our experiments revealed that pacemaker neurons impose rhythmic activity and excitability on LK- and LK-R-expressing neurons. We also found pacemaker neuron-dependent activity rhythms in a second circadian output pathway controlled by DH44 neuropeptide-expressing neurons. We conclude that rhythmic clock neuron activity propagates to multiple downstream circuits to orchestrate behavioral rhythms.

  7. Localization of individual area neuronal activity.

    PubMed

    Hironaga, N; Ioannides, A A

    2007-02-15

    A family of methods, collectively known as independent component analysis (ICA), has recently been added to the array of methods designed to decompose a multi-channel signal into components. ICA methods have been applied to raw magnetoencephalography (MEG) and electroencephalography (EEG) signals to remove artifacts, especially when sources such as power line or cardiac activity generate strong components that dominate the signal. More recently, successful ICA extraction of stimulus-evoked responses has been reported from single-trial raw MEG and EEG signals. The extraction of weak components has often been erratic, depending on which ICA method is employed and even on what parameters are used. In this work, we show that if the emphasis is placed on individual "independent components," as is usually the case with standard ICA applications, differences in the results obtained for different components are exaggerated. We propose instead the reconstruction of regional brain activations by combining tomographic estimates of individual independent components that have been selected by appropriate spatial and temporal criteria. Such localization of individual area neuronal activity (LIANA) allows reliable semi-automatic extraction of single-trial regional activations from raw MEG data. We demonstrate the new method with three different ICA algorithms applied to both computer-generated signals and real data. We show that LIANA provides almost identical results with each ICA method despite the fact that each method yields different individual components.

  8. Optogenetic Activation of Septal Glutamatergic Neurons Drive Hippocampal Theta Rhythms.

    PubMed

    Robinson, Jennifer; Manseau, Frédéric; Ducharme, Guillaume; Amilhon, Bénédicte; Vigneault, Erika; El Mestikawy, Salah; Williams, Sylvain

    2016-03-09

    The medial septum and diagonal band of Broca (MS-DBB) has an essential role for theta rhythm generation in the hippocampus and is critical for learning and memory. The MS-DBB contains cholinergic, GABAergic, and recently described glutamatergic neurons, but their specific contribution to theta generation is poorly understood. Here, we examined the role of MS-DBB glutamatergic neurons in theta rhythm using optogenetic activation and electrophysiological recordings performed in in vitro preparations and in freely behaving mice. The experiments in slices suggest that MS-DBB glutamatergic neurons provide prominent excitatory inputs to a majority of local GABAergic and a minority of septal cholinergic neurons. In contrast, activation of MS-DBB glutamatergic fiber terminals in hippocampal slices elicited weak postsynaptic responses in hippocampal neurons. In the in vitro septo-hippocampal preparation, activation of MS-DBB glutamatergic neurons did increase the rhythmicity of hippocampal theta oscillations, whereas stimulation of septo-hippocampal glutamatergic fibers in the fornix did not have an effect. In freely behaving mice, activation of these neurons in the MS-DBB strongly synchronized hippocampal theta rhythms over a wide range of frequencies, whereas activation of their projections to the hippocampus through fornix stimulations had no effect on theta rhythms, suggesting that MS-DBB glutamatergic neurons played a role in theta generation through local modulation of septal neurons. Together, these results provide the first evidence that MS-DBB glutamatergic neurons modulate local septal circuits, which in turn contribute to theta rhythms in the hippocampus.

  9. A robust activity marking system for exploring active neuronal ensembles

    PubMed Central

    Sørensen, Andreas T; Cooper, Yonatan A; Baratta, Michael V; Weng, Feng-Ju; Zhang, Yuxiang; Ramamoorthi, Kartik; Fropf, Robin; LaVerriere, Emily; Xue, Jian; Young, Andrew; Schneider, Colleen; Gøtzsche, Casper René; Hemberg, Martin; Yin, Jerry CP; Maier, Steven F; Lin, Yingxi

    2016-01-01

    Understanding how the brain captures transient experience and converts it into long lasting changes in neural circuits requires the identification and investigation of the specific ensembles of neurons that are responsible for the encoding of each experience. We have developed a Robust Activity Marking (RAM) system that allows for the identification and interrogation of ensembles of neurons. The RAM system provides unprecedented high sensitivity and selectivity through the use of an optimized synthetic activity-regulated promoter that is strongly induced by neuronal activity and a modified Tet-Off system that achieves improved temporal control. Due to its compact design, RAM can be packaged into a single adeno-associated virus (AAV), providing great versatility and ease of use, including application to mice, rats, flies, and potentially many other species. Cre-dependent RAM, CRAM, allows for the study of active ensembles of a specific cell type and anatomical connectivity, further expanding the RAM system’s versatility. DOI: http://dx.doi.org/10.7554/eLife.13918.001 PMID:27661450

  10. Reversible, activity-dependent targeting of profilin to neuronal nuclei

    SciTech Connect

    Birbach, Andreas . E-mail: andreas.birbach@lbicr.lbg.ac.at; Verkuyl, J. Martin; Matus, Andrew . E-mail: aim@fmi.ch

    2006-07-15

    The actin cytoskeleton in pyramidal neurons plays a major role in activity-dependent processes underlying neuronal plasticity. The small actin-binding protein profilin shows NMDA receptor-dependent accumulation in dendritic spines, which is correlated with suppression of actin dynamics and long-term stabilization of synaptic morphology. Here we show that following NMDA receptor activation profilin also accumulates in the nucleus of hippocampal neurons via a process involving rearrangement of the actin cytoskeleton. This simultaneous targeting to dendritic spines and the cell nucleus suggests a novel mechanism of neuronal plasticity in which profilin both tags activated synapses and influences nuclear events.

  11. High-throughput imaging of neuronal activity in Caenorhabditis elegans

    PubMed Central

    Larsch, Johannes; Ventimiglia, Donovan; Bargmann, Cornelia I.; Albrecht, Dirk R.

    2013-01-01

    Neuronal responses to sensory inputs can vary based on genotype, development, experience, or stochastic factors. Existing neuronal recording techniques examine a single animal at a time, limiting understanding of the variability and range of potential responses. To scale up neuronal recordings, we here describe a system for simultaneous wide-field imaging of neuronal calcium activity from at least 20 Caenorhabditis elegans animals under precise microfluidic chemical stimulation. This increased experimental throughput was used to perform a systematic characterization of chemosensory neuron responses to multiple odors, odor concentrations, and temporal patterns, as well as responses to pharmacological manipulation. The system allowed recordings from sensory neurons and interneurons in freely moving animals, whose neuronal responses could be correlated with behavior. Wide-field imaging provides a tool for comprehensive circuit analysis with elevated throughput in C. elegans. PMID:24145415

  12. Neural activity triggers neuronal oxidative metabolism followed by astrocytic glycolysis.

    PubMed

    Kasischke, Karl A; Vishwasrao, Harshad D; Fisher, Patricia J; Zipfel, Warren R; Webb, Watt W

    2004-07-02

    We have found that two-photon fluorescence imaging of nicotinamide adenine dinucleotide (NADH) provides the sensitivity and spatial three-dimensional resolution to resolve metabolic signatures in processes of astrocytes and neurons deep in highly scattering brain tissue slices. This functional imaging reveals spatiotemporal partitioning of glycolytic and oxidative metabolism between astrocytes and neurons during focal neural activity that establishes a unifying hypothesis for neurometabolic coupling in which early oxidative metabolism in neurons is eventually sustained by late activation of the astrocyte-neuron lactate shuttle. Our model integrates existing views of brain energy metabolism and is in accord with known macroscopic physiological changes in vivo.

  13. Relationship Between Evoked and Spontaneous Activity in Cultured Neuronal Circuits

    NASA Astrophysics Data System (ADS)

    Kiyohara, Ai; Taguchi, Takahisa; Kudoh, Suguru N.

    Relationship between evoked activity and spontaneous activity in neuronal circuits is one of the important theme for the improvement of neuroprosthetic apparatus. The spontaneous activity and evoked action potentials are mutually related in the cultured neuronal network autonomously reconstructed on the culture dish, but there is a question whether spontaneous activity and the evoked action potentials constitute one state respectively or the spontaneous activity is only a random background noise. Comparing the frequencies and standard deviations of spontaneous activity with those of evoked activity, we found that the silent and reproducible period lasting for 1 sec immediately after the activity evoked primally. In addition, the repetitive stimuli suppress the spontaneously occurring bursting activity in frequency, even though the inter-stimulus-interval was more than 10 sec. These results suggests that distinct internal state of the neuronal circuit was triggered by an electrical stimulation, and there were state of spontaneous mode and evoked mode in a neuronal circuit.

  14. Activation of Pedunculopontine Glutamate Neurons Is Reinforcing.

    PubMed

    Yoo, Ji Hoon; Zell, Vivien; Wu, Johnathan; Punta, Cindy; Ramajayam, Nivedita; Shen, Xinyi; Faget, Lauren; Lilascharoen, Varoth; Lim, Byung Kook; Hnasko, Thomas S

    2017-01-04

    Dopamine transmission from midbrain ventral tegmental area (VTA) neurons underlies behavioral processes related to motivation and drug addiction. The pedunculopontine tegmental nucleus (PPTg) is a brainstem nucleus containing glutamate-, acetylcholine-, and GABA-releasing neurons with connections to basal ganglia and limbic brain regions. Here we investigated the role of PPTg glutamate neurons in reinforcement, with an emphasis on their projections to VTA dopamine neurons. We used cell-type-specific anterograde tracing and optogenetic methods to selectively label and manipulate glutamate projections from PPTg neurons in mice. We used anatomical, electrophysiological, and behavioral assays to determine their patterns of connectivity and ascribe functional roles in reinforcement. We found that photoactivation of PPTg glutamate cell bodies could serve as a direct positive reinforcer on intracranial self-photostimulation assays. Further, PPTg glutamate neurons directly innervate VTA; photostimulation of this pathway preferentially excites VTA dopamine neurons and is sufficient to induce behavioral reinforcement. These results demonstrate that ascending PPTg glutamate projections can drive motivated behavior, and PPTg to VTA synapses may represent an important target relevant to drug addiction and other mental health disorders.

  15. Modulation of AgRP-neuronal function by SOCS3 as an initiating event in diet-induced hypothalamic leptin resistance.

    PubMed

    Olofsson, Louise E; Unger, Elizabeth K; Cheung, Clement C; Xu, Allison W

    2013-02-19

    Chronic consumption of a fat-rich diet leads to attenuation of leptin signaling in hypothalamic neurons, a hallmark feature of cellular leptin resistance. To date, little is known about the temporal and spatial dysregulation of neuronal function under conditions of nutrient excess. We show that agouti-related protein (AgRP)-expressing neurons precede proopiomelanocortin neurons in developing diet-induced cellular leptin resistance. High-fat diet-induced up-regulation of suppressor of cytokine signaling-3 (SOCS3) occurs in AgRP neurons before proopiomelanocortin and other hypothalamic neurons. SOCS3 expression in AgRP neurons increases after 2 d of high-fat feeding, but reduces after switching to a low-fat diet for 1 d. Consistently, transgenic overexpression of SOCS3 in AgRP neurons produces metabolic phenotypes resembling those observed after short-term high-fat feeding. We further show that AgRP neurons are the predominant cell type situated outside the blood-brain barrier in the mediobasal hypothalamus. AgRP neurons are more responsive to low levels of circulating leptin, but they are also more prone to development of leptin resistance in response to a small increase in blood leptin concentrations. Collectively, these results suggest that AgRP neurons are able to sense slight changes in plasma metabolic signals, allowing them to serve as first-line responders to fluctuation of energy intake. Furthermore, modulation of SOCS3 expression in AgRP neurons may play a dynamic and physiological role in metabolic fine tuning in response to short-term changes of nutritional status.

  16. A Ribosomal Protein AgRPS3aE from Halophilic Aspergillus glaucus Confers Salt Tolerance in Heterologous Organisms

    PubMed Central

    Liang, Xilong; Liu, Yiling; Xie, Lixia; Liu, Xiaodan; Wei, Yi; Zhou, Xiaoyang; Zhang, Shihong

    2015-01-01

    High salt in soils is one of the abiotic stresses that significantly reduces crop yield, although saline lands are considered potential resources arable for agriculture. Currently, genetic engineering for enhancing salt tolerance is being tested as an efficient and viable strategy for crop improvement. We previously characterized a large subunit of the ribosomal protein RPL44, which is involved in osmotic stress in the extremely halophilic fungus Aspergillus glaucus. Here, we screened another ribosomal protein (AgRPS3aE) that also produced high-salt tolerance in yeast. Bioinformatics analysis indicated that AgRPS3aE encodes a 29.2 kDa small subunit of a ribosomal protein belonging to the RPS3Ae family in eukaryotes. To further confirm its protective function against salinity, we expressed AgRPS3aE in three heterologous systems, the filamentous fungus Magnaporthe oryzae and two model plants Arabidopsis and tobacco. Overexpression of AgRPS3aE in all tested transformants significantly alleviated stress symptoms compared with controls, suggesting that AgRPS3aE functions not only in fungi but also in plants. Considering that ribosomal proteins are housekeeping components in organisms from prokaryotes to eukaryotes, we propose that AgRPS3aE is one of the optimal genes for improving high-salt tolerance in crops. PMID:25642759

  17. Prefrontal parvalbumin interneurons shape neuronal activity to drive fear expression.

    PubMed

    Courtin, Julien; Chaudun, Fabrice; Rozeske, Robert R; Karalis, Nikolaos; Gonzalez-Campo, Cecilia; Wurtz, Hélène; Abdi, Azzedine; Baufreton, Jerome; Bienvenu, Thomas C M; Herry, Cyril

    2014-01-02

    Synchronization of spiking activity in neuronal networks is a fundamental process that enables the precise transmission of information to drive behavioural responses. In cortical areas, synchronization of principal-neuron spiking activity is an effective mechanism for information coding that is regulated by GABA (γ-aminobutyric acid)-ergic interneurons through the generation of neuronal oscillations. Although neuronal synchrony has been demonstrated to be crucial for sensory, motor and cognitive processing, it has not been investigated at the level of defined circuits involved in the control of emotional behaviour. Converging evidence indicates that fear behaviour is regulated by the dorsomedial prefrontal cortex (dmPFC). This control over fear behaviour relies on the activation of specific prefrontal projections to the basolateral complex of the amygdala (BLA), a structure that encodes associative fear memories. However, it remains to be established how the precise temporal control of fear behaviour is achieved at the level of prefrontal circuits. Here we use single-unit recordings and optogenetic manipulations in behaving mice to show that fear expression is causally related to the phasic inhibition of prefrontal parvalbumin interneurons (PVINs). Inhibition of PVIN activity disinhibits prefrontal projection neurons and synchronizes their firing by resetting local theta oscillations, leading to fear expression. Our results identify two complementary neuronal mechanisms mediated by PVINs that precisely coordinate and enhance the neuronal activity of prefrontal projection neurons to drive fear expression.

  18. Ethanol-Induced Increase of Agouti-Related Protein (AgRP) Immunoreactivity in the Arcuate Nucleus of the Hypothalamus of C57BL/6J, but not 129/SvJ, Inbred Mice

    PubMed Central

    Cubero, Inmaculada; Navarro, Montserrat; Carvajal, Francisca; Lerma-Cabrera, Jose Manuel; Thiele, Todd E.

    2011-01-01

    exposure has direct effects on endogenous AgRP activity in ethanol preferring C57BL/6J mice. It is suggested that ethanol-induced increases in AgRP may be part of a positive feedback system that stimulates excessive binge-like ethanol drinking in C57BL/6J mice. Inherent differences in α-MSH immunoreactivity may contribute to differences in neurobiological responses to ethanol that are characteristically observed between the C57BL/6J and 129/SvJ inbred strains of mice. PMID:20102560

  19. On the Dynamics of the Spontaneous Activity in Neuronal Networks

    PubMed Central

    Bonifazi, Paolo; Ruaro, Maria Elisabetta; Torre, Vincent

    2007-01-01

    Most neuronal networks, even in the absence of external stimuli, produce spontaneous bursts of spikes separated by periods of reduced activity. The origin and functional role of these neuronal events are still unclear. The present work shows that the spontaneous activity of two very different networks, intact leech ganglia and dissociated cultures of rat hippocampal neurons, share several features. Indeed, in both networks: i) the inter-spike intervals distribution of the spontaneous firing of single neurons is either regular or periodic or bursting, with the fraction of bursting neurons depending on the network activity; ii) bursts of spontaneous spikes have the same broad distributions of size and duration; iii) the degree of correlated activity increases with the bin width, and the power spectrum of the network firing rate has a 1/f behavior at low frequencies, indicating the existence of long-range temporal correlations; iv) the activity of excitatory synaptic pathways mediated by NMDA receptors is necessary for the onset of the long-range correlations and for the presence of large bursts; v) blockage of inhibitory synaptic pathways mediated by GABAA receptors causes instead an increase in the correlation among neurons and leads to a burst distribution composed only of very small and very large bursts. These results suggest that the spontaneous electrical activity in neuronal networks with different architectures and functions can have very similar properties and common dynamics. PMID:17502919

  20. Astrocyte Ca2+ Influx Negatively Regulates Neuronal Activity

    PubMed Central

    Ormerod, Kiel G.

    2017-01-01

    Abstract Maintenance of neural circuit activity requires appropriate regulation of excitatory and inhibitory synaptic transmission. Recently, glia have emerged as key partners in the modulation of neuronal excitability; however, the mechanisms by which glia regulate neuronal signaling are still being elucidated. Here, we describe an analysis of how Ca2+ signals within Drosophila astrocyte-like glia regulate excitability in the nervous system. We find that Drosophila astrocytes exhibit robust Ca2+ oscillatory activity manifested by fast, recurrent microdomain Ca2+ fluctuations within processes that infiltrate the synaptic neuropil. Unlike the enhanced neuronal activity and behavioral seizures that were previously observed during manipulations that trigger Ca2+ influx into Drosophila cortex glia, we find that acute induction of astrocyte Ca2+ influx leads to a rapid onset of behavioral paralysis and a suppression of neuronal activity. We observe that Ca2+ influx triggers rapid endocytosis of the GABA transporter (GAT) from astrocyte plasma membranes, suggesting that increased synaptic GABA levels contribute to the neuronal silencing and paralysis. We identify Rab11 as a novel regulator of GAT trafficking that is required for this form of activity regulation. Suppression of Rab11 function strongly offsets the reduction of neuronal activity caused by acute astrocyte Ca2+ influx, likely by inhibiting GAT endocytosis. Our data provide new insights into astrocyte Ca2+ signaling and indicate that distinct glial subtypes in the Drosophila brain can mediate opposing effects on neuronal excitability. PMID:28303263

  1. Neuronal avalanches of a self-organized neural network with active-neuron-dominant structure.

    PubMed

    Li, Xiumin; Small, Michael

    2012-06-01

    Neuronal avalanche is a spontaneous neuronal activity which obeys a power-law distribution of population event sizes with an exponent of -3/2. It has been observed in the superficial layers of cortex both in vivo and in vitro. In this paper, we analyze the information transmission of a novel self-organized neural network with active-neuron-dominant structure. Neuronal avalanches can be observed in this network with appropriate input intensity. We find that the process of network learning via spike-timing dependent plasticity dramatically increases the complexity of network structure, which is finally self-organized to be active-neuron-dominant connectivity. Both the entropy of activity patterns and the complexity of their resulting post-synaptic inputs are maximized when the network dynamics are propagated as neuronal avalanches. This emergent topology is beneficial for information transmission with high efficiency and also could be responsible for the large information capacity of this network compared with alternative archetypal networks with different neural connectivity.

  2. Neuronal avalanches of a self-organized neural network with active-neuron-dominant structure

    NASA Astrophysics Data System (ADS)

    Li, Xiumin; Small, Michael

    2012-06-01

    Neuronal avalanche is a spontaneous neuronal activity which obeys a power-law distribution of population event sizes with an exponent of -3/2. It has been observed in the superficial layers of cortex both invivo and invitro. In this paper, we analyze the information transmission of a novel self-organized neural network with active-neuron-dominant structure. Neuronal avalanches can be observed in this network with appropriate input intensity. We find that the process of network learning via spike-timing dependent plasticity dramatically increases the complexity of network structure, which is finally self-organized to be active-neuron-dominant connectivity. Both the entropy of activity patterns and the complexity of their resulting post-synaptic inputs are maximized when the network dynamics are propagated as neuronal avalanches. This emergent topology is beneficial for information transmission with high efficiency and also could be responsible for the large information capacity of this network compared with alternative archetypal networks with different neural connectivity.

  3. Autaptic regulation of electrical activities in neuron under electromagnetic induction

    PubMed Central

    Xu, Ying; Ying, Heping; Jia, Ya; Ma, Jun; Hayat, Tasawar

    2017-01-01

    Realistic neurons may hold complex anatomical structure, for example, autapse connection to some internuncial neurons, which this specific synapse can connect to its body via a close loop. Continuous exchanges of charged ions across the membrane can induce complex distribution fluctuation of intracellular and extracellular charged ions of cell, and a time-varying electromagnetic field is set to modulate the membrane potential of neuron. In this paper, an autapse-modulated neuron model is presented and the effect of electromagnetic induction is considered by using magnetic flux. Bifurcation analysis and sampled time series for membrane potentials are calculated to investigate the mode transition in electrical activities and the biological function of autapse connection is discussed. Furthermore, the Gaussian white noise and electromagnetic radiation are considered on the improved neuron model, it is found appropriate setting and selection for feedback gain and time delay in autapse can suppress the bursting in neuronal behaviors. It indicates the formation of autapse can enhance the self-adaption of neuron so that appropriate response to external forcing can be selected, this biological function is helpful for encoding and signal propagation of neurons. It can be useful for investigation about collective behaviors in neuronal networks exposed to electromagnetic radiation. PMID:28240314

  4. Autaptic regulation of electrical activities in neuron under electromagnetic induction.

    PubMed

    Xu, Ying; Ying, Heping; Jia, Ya; Ma, Jun; Hayat, Tasawar

    2017-02-27

    Realistic neurons may hold complex anatomical structure, for example, autapse connection to some internuncial neurons, which this specific synapse can connect to its body via a close loop. Continuous exchanges of charged ions across the membrane can induce complex distribution fluctuation of intracellular and extracellular charged ions of cell, and a time-varying electromagnetic field is set to modulate the membrane potential of neuron. In this paper, an autapse-modulated neuron model is presented and the effect of electromagnetic induction is considered by using magnetic flux. Bifurcation analysis and sampled time series for membrane potentials are calculated to investigate the mode transition in electrical activities and the biological function of autapse connection is discussed. Furthermore, the Gaussian white noise and electromagnetic radiation are considered on the improved neuron model, it is found appropriate setting and selection for feedback gain and time delay in autapse can suppress the bursting in neuronal behaviors. It indicates the formation of autapse can enhance the self-adaption of neuron so that appropriate response to external forcing can be selected, this biological function is helpful for encoding and signal propagation of neurons. It can be useful for investigation about collective behaviors in neuronal networks exposed to electromagnetic radiation.

  5. Autaptic regulation of electrical activities in neuron under electromagnetic induction

    NASA Astrophysics Data System (ADS)

    Xu, Ying; Ying, Heping; Jia, Ya; Ma, Jun; Hayat, Tasawar

    2017-02-01

    Realistic neurons may hold complex anatomical structure, for example, autapse connection to some internuncial neurons, which this specific synapse can connect to its body via a close loop. Continuous exchanges of charged ions across the membrane can induce complex distribution fluctuation of intracellular and extracellular charged ions of cell, and a time-varying electromagnetic field is set to modulate the membrane potential of neuron. In this paper, an autapse-modulated neuron model is presented and the effect of electromagnetic induction is considered by using magnetic flux. Bifurcation analysis and sampled time series for membrane potentials are calculated to investigate the mode transition in electrical activities and the biological function of autapse connection is discussed. Furthermore, the Gaussian white noise and electromagnetic radiation are considered on the improved neuron model, it is found appropriate setting and selection for feedback gain and time delay in autapse can suppress the bursting in neuronal behaviors. It indicates the formation of autapse can enhance the self-adaption of neuron so that appropriate response to external forcing can be selected, this biological function is helpful for encoding and signal propagation of neurons. It can be useful for investigation about collective behaviors in neuronal networks exposed to electromagnetic radiation.

  6. Anti-Hu antibodies activate enteric and sensory neurons

    PubMed Central

    Li, Qin; Michel, Klaus; Annahazi, Anita; Demir, Ihsan E.; Ceyhan, Güralp O.; Zeller, Florian; Komorowski, Lars; Stöcker, Winfried; Beyak, Michael J.; Grundy, David; Farrugia, Gianrico; De Giorgio, Roberto; Schemann, Michael

    2016-01-01

    IgG of type 1 anti-neuronal nuclear antibody (ANNA-1, anti-Hu) specificity is a serological marker of paraneoplastic neurological autoimmunity (including enteric/autonomic) usually related to small-cell lung carcinoma. We show here that IgG isolated from such sera and also affinity-purified anti-HuD label enteric neurons and cause an immediate spike discharge in enteric and visceral sensory neurons. Both labelling and activation of enteric neurons was prevented by preincubation with the HuD antigen. Activation of enteric neurons was inhibited by the nicotinic receptor antagonists hexamethonium and dihydro-β-erythroidine and reduced by the P2X antagonist pyridoxal phosphate-6-azo (benzene-2,4-disulfonic acid (PPADS) but not by the 5-HT3 antagonist tropisetron or the N-type Ca-channel blocker ω-Conotoxin GVIA. Ca++ imaging experiments confirmed activation of enteric neurons but not enteric glia. These findings demonstrate a direct excitatory action of ANNA-1, in particular anti-HuD, on visceral sensory and enteric neurons, which involves nicotinic and P2X receptors. The results provide evidence for a novel link between nerve activation and symptom generation in patients with antibody-mediated gut dysfunction. PMID:27905561

  7. Regulation of neuronal P53 activity by CXCR4

    PubMed Central

    Khan, Muhammad Z.; Shimizu, Saori; Patel, Jeegar P.; Nelson, Autumn; Le, My-Thao; Mullen-Przeworski, Anna; Brandimarti, Renato; Fatatis, Alessandro; Meucci, Olimpia

    2009-01-01

    Abnormal activation of CXCR4 during inflammatory/infectious states may lead to neuronal dysfunction or damage. The major goal of this study was to determine the coupling of CXCR4 to p53-dependent survival pathways in primary neurons. Neurons were stimulated with the HIV envelope protein gp120IIIB or the endogenous CXCR4 agonist, SDF-1α. We found that gp120 stimulates p53 activity and induces expression of the p53 pro-apoptotic target Apaf-1 in cultured neurons. Inhibition of CXCR4 by AMD3100 abrogates the effect of gp120 on both p53 and Apaf-1. Moreover, gp120 neurotoxicity is markedly reduced by the p53-inhibitor, pifithrin-α. The viral protein also regulates p53 phosphorylation and expression of other p53-responsive genes, such as MDM2 and p21. Conversely, SDF-1α, which can promote neuronal survival, increases p53 acetylation and p21 expression in neurons. Thus, the stimulation of different p53 targets could be instrumental in determining the outcome of CXCR4 activation on neuronal survival in neuroinflammatory disorders. PMID:16005638

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

    PubMed

    Ye, Hui; Steiger, Amanda

    2015-08-12

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

  9. Activity patterns of serotonin neurons underlying cognitive flexibility.

    PubMed

    Matias, Sara; Lottem, Eran; Dugué, Guillaume P; Mainen, Zachary F

    2017-03-21

    Serotonin is implicated in mood and affective disorders. However, growing evidence suggests that a core endogenous role is to promote flexible adaptation to changes in the causal structure of the environment, through behavioral inhibition and enhanced plasticity. We used long-term photometric recordings in mice to study a population of dorsal raphe serotonin neurons, whose activity we could link to normal reversal learning using pharmacogenetics. We found that these neurons are activated by both positive and negative prediction errors, and thus report signals similar to those proposed to promote learning in conditions of uncertainty. Furthermore, by comparing the cue responses of serotonin and dopamine neurons, we found differences in learning rates that could explain the importance of serotonin in inhibiting perseverative responding. Our findings show how the activity patterns of serotonin neurons support a role in cognitive flexibility, and suggest a revised model of dopamine-serotonin opponency with potential clinical implications.

  10. Neuronal activity-dependent membrane traffic at the neuromuscular junction

    PubMed Central

    Miana-Mena, Francisco Javier; Roux, Sylvie; Benichou, Jean-Claude; Osta, Rosario; Brûlet, Philippe

    2002-01-01

    During development and also in adulthood, synaptic connections are modulated by neuronal activity. To follow such modifications in vivo, new genetic tools are designed. The nontoxic C-terminal fragment of tetanus toxin (TTC) fused to a reporter gene such as LacZ retains the retrograde and transsynaptic transport abilities of the holotoxin itself. In this work, the hybrid protein is injected intramuscularly to analyze in vivo the mechanisms of intracellular and transneuronal traffics at the neuromuscular junction (NMJ). Traffic on both sides of the synapse are strongly dependent on presynaptic neural cell activity. In muscle, a directional membrane traffic concentrates β-galactosidase-TTC hybrid protein into the NMJ postsynaptic side. In neurons, the probe is sorted across the cell to dendrites and subsequently to an interconnected neuron. Such fusion protein, sensitive to presynaptic neuronal activity, would be extremely useful to analyze morphological changes and plasticity at the NMJ. PMID:11880654

  11. Sleep active cortical neurons expressing neuronal nitric oxide synthase are active after both acute sleep deprivation and chronic sleep restriction.

    PubMed

    Zielinski, M R; Kim, Y; Karpova, S A; Winston, S; McCarley, R W; Strecker, R E; Gerashchenko, D

    2013-09-05

    Non-rapid eye movement (NREM) sleep electroencephalographic (EEG) delta power (~0.5-4 Hz), also known as slow wave activity (SWA), is typically enhanced after acute sleep deprivation (SD) but not after chronic sleep restriction (CSR). Recently, sleep-active cortical neurons expressing neuronal nitric oxide synthase (nNOS) were identified and associated with enhanced SWA after short acute bouts of SD (i.e., 6h). However, the relationship between cortical nNOS neuronal activity and SWA during CSR is unknown. We compared the activity of cortical neurons expressing nNOS (via c-Fos and nNOS immuno-reactivity, respectively) and sleep in rats in three conditions: (1) after 18-h of acute SD; (2) after five consecutive days of sleep restriction (SR) (18-h SD per day with 6h ad libitum sleep opportunity per day); (3) and time-of-day matched ad libitum sleep controls. Cortical nNOS neuronal activity was enhanced during sleep after both 18-h SD and 5 days of SR treatments compared to control treatments. SWA and NREM sleep delta energy (the product of NREM sleep duration and SWA) were positively correlated with enhanced cortical nNOS neuronal activity after 18-h SD but not 5days of SR. That neurons expressing nNOS were active after longer amounts of acute SD (18h vs. 6h reported in the literature) and were correlated with SWA further suggest that these cells might regulate SWA. However, since these neurons were active after CSR when SWA was not enhanced, these findings suggest that mechanisms downstream of their activation are altered during CSR.

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

    PubMed

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

    2013-01-03

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

  13. Human Temporal Cortical Single Neuron Activity during Language: A Review

    PubMed Central

    Ojemann, George A.

    2013-01-01

    Findings from recordings of human temporal cortical single neuron activity during several measures of language, including object naming and word reading are reviewed and related to changes in activity in the same neurons during recent verbal memory and verbal associative learning measures, in studies conducted during awake neurosurgery for the treatment of epilepsy. The proportion of neurons changing activity with language tasks was similar in either hemisphere. Dominant hemisphere activity was characterized by relative inhibition, some of which occurred during overt speech, possibly to block perception of one’s own voice. However, the majority seems to represent a dynamic network becoming active with verbal memory encoding and especially verbal learning, but inhibited during performance of overlearned language tasks. Individual neurons are involved in different networks for different aspects of language, including naming or reading and naming in different languages. The majority of the changes in activity were tonic sustained shifts in firing. Patterned phasic activity for specific language items was very infrequently recorded. Human single neuron recordings provide a unique perspective on the biologic substrate for language, for these findings are in contrast to many of the findings from other techniques for investigating this. PMID:24961418

  14. Nitric Oxide Regulates Neuronal Activity via Calcium-Activated Potassium Channels

    PubMed Central

    Zhong, Lei Ray; Estes, Stephen; Artinian, Liana; Rehder, Vincent

    2013-01-01

    Nitric oxide (NO) is an unconventional membrane-permeable messenger molecule that has been shown to play various roles in the nervous system. How NO modulates ion channels to affect neuronal functions is not well understood. In gastropods, NO has been implicated in regulating the feeding motor program. The buccal motoneuron, B19, of the freshwater pond snail Helisoma trivolvis is active during the hyper-retraction phase of the feeding motor program and is located in the vicinity of NO-producing neurons in the buccal ganglion. Here, we asked whether B19 neurons might serve as direct targets of NO signaling. Previous work established NO as a key regulator of growth cone motility and neuronal excitability in another buccal neuron involved in feeding, the B5 neuron. This raised the question whether NO might modulate the electrical activity and neuronal excitability of B19 neurons as well, and if so whether NO acted on the same or a different set of ion channels in both neurons. To study specific responses of NO on B19 neurons and to eliminate indirect effects contributed by other cells, the majority of experiments were performed on single cultured B19 neurons. Addition of NO donors caused a prolonged depolarization of the membrane potential and an increase in neuronal excitability. The effects of NO could mainly be attributed to the inhibition of two types of calcium-activated potassium channels, apamin-sensitive and iberiotoxin-sensitive potassium channels. NO was found to also cause a depolarization in B19 neurons in situ, but only after NO synthase activity in buccal ganglia had been blocked. The results suggest that NO acts as a critical modulator of neuronal excitability in B19 neurons, and that calcium-activated potassium channels may serve as a common target of NO in neurons. PMID:24236040

  15. Activating neurons by light in free-moving adult flies

    NASA Astrophysics Data System (ADS)

    Wu, Ming-Chin; Hsiao, Po-Yen; Chu, Li-An; Lin, Yen-Yin; Fu, Chien-Chung; Chiang, Ann-Shyn

    2015-01-01

    In this presentation, we show our preliminary results which is related to neurons activation in vivo by laser. A laser scanning system was adopted to guide laser beam to an assigned fly and an assigned position. A 473-nm laser can be a heat punishment source to restrain a wild-type fly's moving area. Furthermore, neurons in optogenetics transgene flies can be triggered by the blue laser in this system.

  16. Altered neuronal responses to feeding-relevant peptides as sign of developmental plasticity in the hypothalamic regulatory system of body weight.

    PubMed

    Davidowa, Helga; Li, Yuzhen; Plagemann, Andreas

    2003-01-01

    Neuronal plasticity during the critical postnatal period of development seems to promote a change in the function of the hypothalamic regulatory system of body weight. Rats raised in small litters (SL) of only three pups per mother compared to ten or twelve in control litters (CL) gain significantly more weight than normal rats till weaning and are overweight also in later life. These rats are known to express hyperleptinemia, hyperglycemia and hyperinsulinemia. The review summarizes the results of action of leptin and insulin as well as of several feeding-relevant neuropeptides on neuronal activity of hypothalamic regulatory centres in overweight SL rats compared to controls. The study was performed on brain slices perfused with solution containing 10 mM glucose. Whereas a normally inhibitory action of leptin and insulin on medial arcuate neurons (ArcM) is reduced in SL rats and partly replaced by activation, the normally activating effect of these hormones on ventromedial (VMH) neurons is altered to predominant inhibition. Inhibition of ArcM neurons may decrease the release of the orexigenic neuropeptide Y (NPY) and agouti gene-related protein (AGRP). Thus, the negative feedback by leptin and insulin on food intake is replaced by diminished response and partly positive feedback processes in SL rats. The action of NPY and AGRP as well as of the orexigenic melanin-concentrating hormone on paraventricular (PVH) and VMH neurons is also shaped from activation or bimodal effects to predominant inhibition. Such inhibition of PVH and VMH might lead to reduced energy expenditure in small litter rats. Also the anorexigenic melanocortin alpha-MSH seems to contribute into increased energy storage. These altered responses of hypothalamic neurons in overweight small litter rats might reflect a general mechanism of neurochemical plasticity and "malprogramming" of hypothalamic neuropeptidergic systems leading to a permanently altered regulatory function.

  17. Methamphetamine Regulation of Firing Activity of Dopamine Neurons.

    PubMed

    Lin, Min; Sambo, Danielle; Khoshbouei, Habibeh

    2016-10-05

    Methamphetamine (METH) is a substrate for the dopamine transporter that increases extracellular dopamine levels by competing with dopamine uptake and increasing reverse transport of dopamine via the transporter. METH has also been shown to alter the excitability of dopamine neurons. The mechanism of METH regulation of the intrinsic firing behaviors of dopamine neurons is less understood. Here we identified an unexpected and unique property of METH on the regulation of firing activity of mouse dopamine neurons. METH produced a transient augmentation of spontaneous spike activity of midbrain dopamine neurons that was followed by a progressive reduction of spontaneous spike activity. Inspection of action potential morphology revealed that METH increased the half-width and produced larger coefficients of variation of the interspike interval, suggesting that METH exposure affected the activity of voltage-dependent potassium channels in these neurons. Since METH has been shown to affect Ca(2+) homeostasis, the unexpected findings that METH broadened the action potential and decreased the amplitude of afterhyperpolarization led us to ask whether METH alters the activity of Ca(2+)-activated potassium (BK) channels. First, we identified BK channels in dopamine neurons by their voltage dependence and their response to a BK channel blocker or opener. While METH suppressed the amplitude of BK channel-mediated unitary currents, the BK channel opener NS1619 attenuated the effects of METH on action potential broadening, afterhyperpolarization repression, and spontaneous spike activity reduction. Live-cell total internal reflection fluorescence microscopy, electrophysiology, and biochemical analysis suggest METH exposure decreased the activity of BK channels by decreasing BK-α subunit levels at the plasma membrane.

  18. Isoperiodic neuronal activity in suprachiasmatic nucleus of the rat

    NASA Technical Reports Server (NTRS)

    Miller, J. D.; Fuller, C. A.

    1992-01-01

    A subpopulation of neurons in the suprachiasmatic nucleus (SCN) is shown here to exhibit isoperiodic bursting activity. The period of discharge in these cells may be lengthened or the periodicity may be transiently disrupted by photic stimulation. It is suggested that many, if not all, of these cells are vasoactive intestinal polypeptide (VIP) neurons. It is shown that the ultradian periodicity of these cells, estimates of the VIP neuron population size in the SCN, effects of partial lesions on tau (period), and estimates of the phase stability of SCN-driven circadian rhythms are consistent with a strongly coupled, multioscillator model of circadian rhythmicity, in which the oscillator population constitutes a restricted subset of the SCN neuronal population.

  19. Effects of periodic stimulation on an overly activated neuronal circuit

    NASA Astrophysics Data System (ADS)

    Kwon, Okyu; Kim, Kiwoong; Park, Sungwon; Moon, Hie-Tae

    2011-08-01

    Motivated by therapeutic deep brain stimulation, we carried out a model study on the effects of periodic stimulation on an overly activated neuronal circuit. Our neuronal circuit, modeled as a small-world network of noisy Hodgkin-Huxley neurons, is controlled to undergo the mechanism of coherence resonance to exhibit spontaneous synchronization of neuronal firing. This state of energy burst is then directly modulated by a chain of electric pulses. Our study shows that (i) the stimulation blocks the synchronization by generating traveling waves, (ii) only the pulse with proper frequency can block the synchronization, and (iii) the effects of stimulation are completely reversible. It is also found that the stimulation is effective only when the network maintains fairly good structural regularity.

  20. Multisynaptic activity in a pyramidal neuron model and neural code.

    PubMed

    Ventriglia, Francesco; Di Maio, Vito

    2006-01-01

    The highly irregular firing of mammalian cortical pyramidal neurons is one of the most striking observation of the brain activity. This result affects greatly the discussion on the neural code, i.e. how the brain codes information transmitted along the different cortical stages. In fact it seems to be in favor of one of the two main hypotheses about this issue, named the rate code. But the supporters of the contrasting hypothesis, the temporal code, consider this evidence inconclusive. We discuss here a leaky integrate-and-fire model of a hippocampal pyramidal neuron intended to be biologically sound to investigate the genesis of the irregular pyramidal firing and to give useful information about the coding problem. To this aim, the complete set of excitatory and inhibitory synapses impinging on such a neuron has been taken into account. The firing activity of the neuron model has been studied by computer simulation both in basic conditions and allowing brief periods of over-stimulation in specific regions of its synaptic constellation. Our results show neuronal firing conditions similar to those observed in experimental investigations on pyramidal cortical neurons. In particular, the variation coefficient (CV) computed from the inter-spike intervals (ISIs) in our simulations for basic conditions is close to the unity as that computed from experimental data. Our simulation shows also different behaviors in firing sequences for different frequencies of stimulation.

  1. Spontaneous cortical activity in awake monkeys composed of neuronal avalanches.

    PubMed

    Petermann, Thomas; Thiagarajan, Tara C; Lebedev, Mikhail A; Nicolelis, Miguel A L; Chialvo, Dante R; Plenz, Dietmar

    2009-09-15

    Spontaneous neuronal activity is an important property of the cerebral cortex but its spatiotemporal organization and dynamical framework remain poorly understood. Studies in reduced systems--tissue cultures, acute slices, and anesthetized rats--show that spontaneous activity forms characteristic clusters in space and time, called neuronal avalanches. Modeling studies suggest that networks with this property are poised at a critical state that optimizes input processing, information storage, and transfer, but the relevance of avalanches for fully functional cerebral systems has been controversial. Here we show that ongoing cortical synchronization in awake rhesus monkeys carries the signature of neuronal avalanches. Negative LFP deflections (nLFPs) correlate with neuronal spiking and increase in amplitude with increases in local population spike rate and synchrony. These nLFPs form neuronal avalanches that are scale-invariant in space and time and with respect to the threshold of nLFP detection. This dimension, threshold invariance, describes a fractal organization: smaller nLFPs are embedded in clusters of larger ones without destroying the spatial and temporal scale-invariance of the dynamics. These findings suggest an organization of ongoing cortical synchronization that is scale-invariant in its three fundamental dimensions--time, space, and local neuronal group size. Such scale-invariance has ontogenetic and phylogenetic implications because it allows large increases in network capacity without a fundamental reorganization of the system.

  2. Transient activation of midbrain dopamine neurons by reward risk.

    PubMed

    Fiorillo, C D

    2011-12-01

    Dopamine neurons of the ventral midbrain are activated transiently following stimuli that predict future reward. This response has been shown to signal the expected value of future reward, and there is strong evidence that it drives positive reinforcement of stimuli and actions associated with reward in accord with reinforcement learning models. Behavior is also influenced by reward uncertainty, or risk, but it is not known whether the transient response of dopamine neurons is sensitive to reward risk. To investigate this, monkeys were trained to associate distinct visual stimuli with certain or uncertain volumes of juice of nearly the same expected value. In a choice task, monkeys preferred the stimulus predicting an uncertain (risky) reward outcome. In a Pavlovian task, in which the neuronal responses to each stimulus could be measured in isolation, it was found that dopamine neurons were more strongly activated by the stimulus associated with reward risk. Given extensive evidence that dopamine drives reinforcement, these results strongly suggest that dopamine neurons can reinforce risk-seeking behavior (gambling), at least under certain conditions. Risk-seeking behavior has the virtue of promoting exploration and learning, and these results support the hypothesis that dopamine neurons represent the value of exploration.

  3. Predicting Single-Neuron Activity in Locally Connected Networks

    PubMed Central

    Azhar, Feraz; Anderson, William S.

    2014-01-01

    The characterization of coordinated activity in neuronal populations has received renewed interest in the light of advancing experimental techniques that allow recordings from multiple units simultaneously. Across both in vitro and in vivo preparations, nearby neurons show coordinated responses when spontaneously active and when subject to external stimuli. Recent work (Truccolo, Hochberg, & Donoghue, 2010) has connected these coordinated responses to behavior, showing that small ensembles of neurons in arm-related areas of sensorimotor cortex can reliably predict single-neuron spikes in behaving monkeys and humans. We investigate this phenomenon using an analogous point process model, showing that in the case of a computational model of cortex responding to random background inputs, one is similarly able to predict the future state of a single neuron by considering its own spiking history, together with the spiking histories of randomly sampled ensembles of nearby neurons. This model exhibits realistic cortical architecture and displays bursting episodes in the two distinct connectivity schemes studied. We conjecture that the baseline predictability we find in these instances is characteristic of locally connected networks more broadly considered. PMID:22845824

  4. Phasic activation of ventral tegmental neurons increases response and pattern similarity in prefrontal cortex neurons

    PubMed Central

    Iwashita, Motoko

    2014-01-01

    Dopamine is critical for higher neural processes and modifying the activity of the prefrontal cortex (PFC). However, the mechanism of dopamine contribution to the modification of neural representation is unclear. Using in vivo two-photon population Ca2+ imaging in awake mice, this study investigated how neural representation of visual input to PFC neurons is regulated by dopamine. Phasic stimulation of dopaminergic neurons in the ventral tegmental area (VTA) evoked prolonged Ca2+ transients, lasting ∼30 s in layer 2/3 neurons of the PFC, which are regulated by a dopamine D1 receptor-dependent pathway. Furthermore, only a conditioning protocol with visual sensory input applied 0.5 s before the VTA dopaminergic input could evoke enhanced Ca2+ transients and increased pattern similarity (or establish a neural representation) of PFC neurons to the same sensory input. By increasing both the level of neuronal response and pattern similarity, dopaminergic input may establish robust and reliable cortical representation. DOI: http://dx.doi.org/10.7554/eLife.02726.001 PMID:25269147

  5. PDF neuron firing phase-shifts key circadian activity neurons in Drosophila.

    PubMed

    Guo, Fang; Cerullo, Isadora; Chen, Xiao; Rosbash, Michael

    2014-06-17

    Our experiments address two long-standing models for the function of the Drosophila brain circadian network: a dual oscillator model, which emphasizes the primacy of PDF-containing neurons, and a cell-autonomous model for circadian phase adjustment. We identify five different circadian (E) neurons that are a major source of rhythmicity and locomotor activity. Brief firing of PDF cells at different times of day generates a phase response curve (PRC), which mimics a light-mediated PRC and requires PDF receptor expression in the five E neurons. Firing also resembles light by causing TIM degradation in downstream neurons. Unlike light however, firing-mediated phase-shifting is CRY-independent and exploits the E3 ligase component CUL-3 in the early night to degrade TIM. Our results suggest that PDF neurons integrate light information and then modulate the phase of E cell oscillations and behavioral rhythms. The results also explain how fly brain rhythms persist in constant darkness and without CRY.

  6. Leptin excites POMC neurons via activation of TRPC channels

    PubMed Central

    Qiu, Jian; Fang, Yuan; Rønnekleiv, Oline K.; Kelly, Martin J.

    2010-01-01

    Leptin can exert its potent appetite-suppressing effects via activation of hypothalamic proopiomelanocortin (POMC) neurons. It depolarizes POMC neurons via activation of a yet unidentified non-selective cation current. Therefore, we sought to identify the conductance activated by leptin using whole cell recording in EGFP-POMC neurons from transgenic mice. The TRPC channel blockers SKF96365, FFA and 2-APB potently inhibited the leptin-induced current. Also, lanthanum (La3+) and intracellular Ca2+ potentiated the effects of leptin. Moreover, the DAG permeable analog OAG failed to activate any TRPC current. Using a Cs+-gluconate-based internal solution, leptin-activated current reversed near -20 mV. After replacement of external Na+ and K+ with Cs+, the reversal shifted to near 0 mV, and the I/V curve exhibited a negative slope conductance at voltages more negative than –40 mV. Based on scRT-PCR, TRPC1 and TRPC4-7 mRNA were expressed in POMC neurons with TRPC5 being the most prevalent. The leptin-induced current was blocked by Jak2 inhibitor AG490, the PI3 Kinase inhibitor wortmannin and the phospholipase C inhibitors, U73122 and ET-18-OCH3. Notably, we identified PLCγ1 transcripts in the majority of POMC neurons. Therefore, leptin through a Jak2-PI3 kinase-PLCγ pathway activates TRPC channels, and TRPC1, 4 and 5 appear to be the key channels mediating the depolarizing effects of leptin in POMC neurons. PMID:20107083

  7. Diminished neuronal activity increases neuron-neuron connectivity underlying silent synapse formation and the rapid conversion of silent to functional synapses.

    PubMed

    Nakayama, Kimiko; Kiyosue, Kazuyuki; Taguchi, Takahisa

    2005-04-20

    Neuronal activity regulates the synaptic strength of neuronal networks. However, it is still unclear how diminished activity changes connection patterns in neuronal circuits. To address this issue, we analyzed neuronal connectivity and relevant mechanisms using hippocampal cultures in which developmental synaptogenesis had occurred. We show that diminution of network activity in mature neuronal circuit promotes reorganization of neuronal circuits via NR2B subunit-containing NMDA-type glutamate receptors (NR2B-NMDARs), which mediate silent synapse formation. Simultaneous double whole-cell recordings revealed that diminishing neuronal circuit activity for 48 h increased the number of synaptically connected neuron pairs with both silent and functional synapses. This increase was accompanied by the specific expression of NR2B-NMDARs at synaptic sites. Analysis of miniature EPSCs (mEPSCs) showed that the frequency of NMDAR-mediated, but not AMPAR-mediated, mEPSCs increased, indicating that diminished neuronal activity promotes silent synapse formation via the surface delivering NR2B-NMDARs in mature neurons. After activation of neuronal circuit by releasing from TTX blockade (referred as circuit reactivation), the frequency of AMPAR-mediated mEPSCs increased instead, and this increase was prevented by ifenprodil. The circuit reactivation also caused an increased colocalization of glutamate receptor 1-specfic and synaptic NR2B-specific puncta. These results indicate that the circuit reactivation converts rapidly silent synapses formed during activity suppression to functional synapses. These data may provide a new example of homeostatic circuit plasticity that entails the modulation of neuron-neuron connectivity by synaptic activity.

  8. Subthalamic nucleus neuronal activity in Parkinson's disease and epilepsy subjects.

    PubMed

    Montgomery, Erwin B

    2008-01-01

    Activity from 113 subthalamic nucleus (STN) neurons from two epilepsy patients and 103 neurons from 9 Parkinson's disease (PD) patients undergoing DBS surgery showed no significant differences in frequencies (PD, mean 7.5+/-7.0 spikes/s (sps), epilepsy mean 7.8+/-8.5 sps) or in the coefficients of variation of mean discharge frequencies per 1s epochs. A striking relationship between mean discharge frequencies per 1 s epochs and the standard deviations for both groups were consistent with a random Poisson processes. These and similar findings call into question theories that posit increased STN activity is causal to parkinsonism.

  9. Selective Activation of Neuronal Targets With Sinusoidal Electric Stimulation

    PubMed Central

    Freeman, Daniel K.; Eddington, Donald K.; Rizzo, Joseph F.

    2010-01-01

    Electric stimulation of the CNS is being evaluated as a treatment modality for a variety of neurological, psychiatric, and sensory disorders. Despite considerable success in some applications, existing stimulation techniques offer little control over which cell types or neuronal substructures are activated by stimulation. The ability to more precisely control neuronal activation would likely improve the clinical outcomes associated with these applications. Here, we show that specific frequencies of sinusoidal stimulation can be used to preferentially activate certain retinal cell types: photoreceptors are activated at 5 Hz, bipolar cells at 25 Hz, and ganglion cells at 100 Hz. In addition, low-frequency stimulation (≤25 Hz) did not activate passing axons but still elicited robust synaptically mediated responses in ganglion cells; therefore, elicited neural activity is confined to within a focal region around the stimulating electrode. Our results suggest that sinusoidal stimulation provides significantly improved control over elicited neural activity relative to conventional pulsatile stimulation. PMID:20810683

  10. Vasoactive intestinal peptide and electrical activity influence neuronal survival

    SciTech Connect

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

    1986-02-01

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

  11. Kisspeptin Regulation of Neuronal Activity throughout the Central Nervous System

    PubMed Central

    Liu, Xinhuai

    2016-01-01

    Kisspeptin signaling at the gonadotropin-releasing hormone (GnRH) neuron is now relatively well characterized and established as being critical for the neural control of fertility. However, kisspeptin fibers and the kisspeptin receptor (KISS1R) are detected throughout the brain suggesting that kisspeptin is involved in regulating the activity of multiple neuronal circuits. We provide here a review of kisspeptin actions on neuronal populations throughout the brain including the magnocellular oxytocin and vasopressin neurons, and cells within the arcuate nucleus, hippocampus, and amygdala. The actions of kisspeptin in these brain regions are compared to its effects upon GnRH neurons. Two major themes arise from this analysis. First, it is apparent that kisspeptin signaling through KISS1R at the GnRH neuron is a unique, extremely potent form or neurotransmission whereas kisspeptin actions through KISS1R in other brain regions exhibit neuromodulatory actions typical of other neuropeptides. Second, it is becoming increasingly likely that kisspeptin acts as a neuromodulator not only through KISS1R but also through other RFamide receptors such as the neuropeptide FF receptors (NPFFRs). We suggest likely locations of kisspeptin signaling through NPFFRs but note that only limited tools are presently available for examining kisspeptin cross-signaling within the RFamide family of neuropeptides. PMID:27246282

  12. Cellular Links between Neuronal Activity and Energy Homeostasis

    PubMed Central

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

    2012-01-01

    Neuronal activity, astrocytic responses to this activity, and energy homeostasis are linked together during baseline, conscious conditions, and short-term rapid activation (as occurs with sensory or motor function). Nervous system energy homeostasis also varies during long-term physiological conditions (i.e., development and aging) and with adaptation to pathological conditions, such as ischemia or low glucose. Neuronal activation requires increased metabolism (i.e., ATP generation) which leads initially to substrate depletion, induction of a variety of signals for enhanced astrocytic function, and increased local blood flow and substrate delivery. Energy generation (particularly in mitochondria) and use during ATP hydrolysis also lead to considerable heat generation. The local increases in blood flow noted following neuronal activation can both enhance local substrate delivery but also provides a heat sink to help cool the brain and removal of waste by-products. In this review we highlight the interactions between short-term neuronal activity and energy metabolism with an emphasis on signals and factors regulating astrocyte function and substrate supply. PMID:22470340

  13. Somatostatin and Somatostatin-Containing Neurons in Shaping Neuronal Activity and Plasticity

    PubMed Central

    Liguz-Lecznar, Monika; Urban-Ciecko, Joanna; Kossut, Malgorzata

    2016-01-01

    Since its discovery over four decades ago, somatostatin (SOM) receives growing scientific and clinical interest. Being localized in the nervous system in a subset of interneurons somatostatin acts as a neurotransmitter or neuromodulator and its role in the fine-tuning of neuronal activity and involvement in synaptic plasticity and memory formation are widely recognized in the recent literature. Combining transgenic animals with electrophysiological, anatomical and molecular methods allowed to characterize several subpopulations of somatostatin-containing interneurons possessing specific anatomical and physiological features engaged in controlling the output of cortical excitatory neurons. Special characteristic and connectivity of somatostatin-containing neurons set them up as significant players in shaping activity and plasticity of the nervous system. However, somatostatin is not just a marker of particular interneuronal subpopulation. Somatostatin itself acts pre- and postsynaptically, modulating excitability and neuronal responses. In the present review, we combine the knowledge regarding somatostatin and somatostatin-containing interneurons, trying to incorporate it into the current view concerning the role of the somatostatinergic system in cortical plasticity. PMID:27445703

  14. Neuronal activity enhances tau propagation and tau pathology in vivo.

    PubMed

    Wu, Jessica W; Hussaini, S Abid; Bastille, Isle M; Rodriguez, Gustavo A; Mrejeru, Ana; Rilett, Kelly; Sanders, David W; Cook, Casey; Fu, Hongjun; Boonen, Rick A C M; Herman, Mathieu; Nahmani, Eden; Emrani, Sheina; Figueroa, Y Helen; Diamond, Marc I; Clelland, Catherine L; Wray, Selina; Duff, Karen E

    2016-08-01

    Tau protein can transfer between neurons transneuronally and trans-synaptically, which is thought to explain the progressive spread of tauopathy observed in the brain of patients with Alzheimer's disease. Here we show that physiological tau released from donor cells can transfer to recipient cells via the medium, suggesting that at least one mechanism by which tau can transfer is via the extracellular space. Neuronal activity has been shown to regulate tau secretion, but its effect on tau pathology is unknown. Using optogenetic and chemogenetic approaches, we found that increased neuronal activity stimulates the release of tau in vitro and enhances tau pathology in vivo. These data have implications for disease pathogenesis and therapeutic strategies for Alzheimer's disease and other tauopathies.

  15. Automated system for analyzing the activity of individual neurons

    NASA Technical Reports Server (NTRS)

    Bankman, Isaac N.; Johnson, Kenneth O.; Menkes, Alex M.; Diamond, Steve D.; Oshaughnessy, David M.

    1993-01-01

    This paper presents a signal processing system that: (1) provides an efficient and reliable instrument for investigating the activity of neuronal assemblies in the brain; and (2) demonstrates the feasibility of generating the command signals of prostheses using the activity of relevant neurons in disabled subjects. The system operates online, in a fully automated manner and can recognize the transient waveforms of several neurons in extracellular neurophysiological recordings. Optimal algorithms for detection, classification, and resolution of overlapping waveforms are developed and evaluated. Full automation is made possible by an algorithm that can set appropriate decision thresholds and an algorithm that can generate templates on-line. The system is implemented with a fast IBM PC compatible processor board that allows on-line operation.

  16. Nanostimulation: manipulation of single neuron activity by juxtacellular current injection.

    PubMed

    Houweling, Arthur R; Doron, Guy; Voigt, Birgit C; Herfst, Lucas J; Brecht, Michael

    2010-03-01

    In the mammalian brain, many thousands of single-neuron recording studies have been performed but less than 10 single-cell stimulation studies. This paucity of single-cell stimulation data reflects a lack of easily applicable single-cell stimulation techniques. We provide a detailed description of the procedures involved in nanostimulation, a single-cell stimulation method derived from the juxtacellular labeling technique. Nanostimulation is easy to apply and can be directed to a wide variety of identifiable neurons in anesthetized and awake animals. We describe the recording approach and the parameters of the electric configuration underlying nanostimulation. We use glass pipettes with a DC resistance of 4-7 Mohms. Obtaining the juxtacellular configuration requires a close contact between pipette tip and neuron and is associated with a several-fold increase in resistance to values > or = 20 Mohms. The recorded action potential (AP) amplitude grows to > or = 2 mV, and neurons can be activated with currents in the nanoampere range--hence the term nanostimulation. While exact AP timing has not been achieved, AP frequency and AP number can be parametrically controlled. We demonstrate that nanostimulation can also be used to selectively inhibit sensory responses in identifiable neurons. Nanostimulation is biophysically similar to electroporation, and based on this assumption, we argue that nanostimulation operates on membranes in the micrometer area directly below the pipette tip, where membrane pores are induced by high transmembrane voltage. There is strong evidence to suggest that nanostimulation selectively activates single neurons and that the evoked effects are cell-specific. Nanostimulation therefore holds great potential for elucidating how single neurons contribute to behavior.

  17. Neuronal activity regulates remyelination via glutamate signalling to oligodendrocyte progenitors

    PubMed Central

    Gautier, Hélène O. B.; Evans, Kimberley A.; Volbracht, Katrin; James, Rachel; Sitnikov, Sergey; Lundgaard, Iben; James, Fiona; Lao-Peregrin, Cristina; Reynolds, Richard; Franklin, Robin J. M.; Káradóttir, Ragnhildur T

    2015-01-01

    Myelin regeneration can occur spontaneously in demyelinating diseases such as multiple sclerosis (MS). However, the underlying mechanisms and causes of its frequent failure remain incompletely understood. Here we show, using an in-vivo remyelination model, that demyelinated axons are electrically active and generate de novo synapses with recruited oligodendrocyte progenitor cells (OPCs), which, early after lesion induction, sense neuronal activity by expressing AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid)/kainate receptors. Blocking neuronal activity, axonal vesicular release or AMPA receptors in demyelinated lesions results in reduced remyelination. In the absence of neuronal activity there is a ∼6-fold increase in OPC number within the lesions and a reduced proportion of differentiated oligodendrocytes. These findings reveal that neuronal activity and release of glutamate instruct OPCs to differentiate into new myelinating oligodendrocytes that recover lost function. Co-localization of OPCs with the presynaptic protein VGluT2 in MS lesions implies that this mechanism may provide novel targets to therapeutically enhance remyelination. PMID:26439639

  18. Neuronal activity in somatosensory cortex related to tactile exploration.

    PubMed

    Fortier-Poisson, Pascal; Smith, Allan M

    2016-01-01

    The very light contact forces (∼0.60 N) applied by the fingertips during tactile exploration reveal a clearly optimized sensorimotor strategy. To investigate the cortical mechanisms involved with this behavior, we recorded 230 neurons in the somatosensory cortex (S1), as two monkeys scanned different surfaces with the fingertips in search of a tactile target without visual feedback. During the exploration, the monkeys, like humans, carefully controlled the finger forces. High-friction surfaces offering greater tangential shear force resistance to the skin were associated with decreased normal contact forces. The activity of one group of neurons was modulated with either the normal or tangential force, with little or no influence from the orthogonal force component. A second group responded to kinetic friction or the ratio of tangential to normal forces rather than responding to a specific parameter, such as force magnitude or direction. A third group of S1 neurons appeared to respond to particular vectors of normal and tangential force on the skin. Although 45 neurons correlated with scanning speed, 32 were also modulated by finger forces, suggesting that forces on the finger should be considered as the primary parameter encoding the skin compliance and that finger speed is a secondary parameter that co-varies with finger forces. Neurons (102) were also tested with different textures, and the activity of 62 of these increased or decreased in relation to the surface friction.

  19. Action observation activates neurons of the monkey ventrolateral prefrontal cortex

    PubMed Central

    Simone, Luciano; Bimbi, Marco; Rodà, Francesca; Fogassi, Leonardo; Rozzi, Stefano

    2017-01-01

    Prefrontal cortex is crucial for exploiting contextual information for the planning and guidance of behavioral responses. Among contextual cues, those provided by others’ behavior are particularly important, in primates, for selecting appropriate reactions and suppressing the inappropriate ones. These latter functions deeply rely on the ability to understand others’ actions. However, it is largely unknown whether prefrontal neurons are activated by action observation. To address this issue, we recorded the activity of ventrolateral prefrontal (VLPF) neurons of macaque monkeys during the observation of videos depicting biological movements performed by a monkey or a human agent, and object motion. Our results show that a population of VLPF neurons respond to the observation of biological movements, in particular those representing goal directed actions. Many of these neurons also show a preference for the agent performing the action. The neural response is present also when part of the observed movement is obscured, suggesting that these VLPF neurons code a high order representation of the observed action rather than a simple visual description of it. PMID:28290511

  20. Neuronal activity in somatosensory cortex related to tactile exploration

    PubMed Central

    Fortier-Poisson, Pascal

    2015-01-01

    The very light contact forces (∼0.60 N) applied by the fingertips during tactile exploration reveal a clearly optimized sensorimotor strategy. To investigate the cortical mechanisms involved with this behavior, we recorded 230 neurons in the somatosensory cortex (S1), as two monkeys scanned different surfaces with the fingertips in search of a tactile target without visual feedback. During the exploration, the monkeys, like humans, carefully controlled the finger forces. High-friction surfaces offering greater tangential shear force resistance to the skin were associated with decreased normal contact forces. The activity of one group of neurons was modulated with either the normal or tangential force, with little or no influence from the orthogonal force component. A second group responded to kinetic friction or the ratio of tangential to normal forces rather than responding to a specific parameter, such as force magnitude or direction. A third group of S1 neurons appeared to respond to particular vectors of normal and tangential force on the skin. Although 45 neurons correlated with scanning speed, 32 were also modulated by finger forces, suggesting that forces on the finger should be considered as the primary parameter encoding the skin compliance and that finger speed is a secondary parameter that co-varies with finger forces. Neurons (102) were also tested with different textures, and the activity of 62 of these increased or decreased in relation to the surface friction. PMID:26467519

  1. Amyloid precursor protein controls cholesterol turnover needed for neuronal activity.

    PubMed

    Pierrot, Nathalie; Tyteca, Donatienne; D'auria, Ludovic; Dewachter, Ilse; Gailly, Philippe; Hendrickx, Aurélie; Tasiaux, Bernadette; Haylani, Laetitia El; Muls, Nathalie; N'kuli, Francisca; Laquerrière, Annie; Demoulin, Jean-Baptiste; Campion, Dominique; Brion, Jean-Pierre; Courtoy, Pierre J; Kienlen-Campard, Pascal; Octave, Jean-Noël

    2013-04-01

    Perturbation of lipid metabolism favours progression of Alzheimer disease, in which processing of Amyloid Precursor Protein (APP) has important implications. APP cleavage is tightly regulated by cholesterol and APP fragments regulate lipid homeostasis. Here, we investigated whether up or down regulation of full-length APP expression affected neuronal lipid metabolism. Expression of APP decreased HMG-CoA reductase (HMGCR)-mediated cholesterol biosynthesis and SREBP mRNA levels, while its down regulation had opposite effects. APP and SREBP1 co-immunoprecipitated and co-localized in the Golgi. This interaction prevented Site-2 protease-mediated processing of SREBP1, leading to inhibition of transcription of its target genes. A GXXXG motif in APP sequence was critical for regulation of HMGCR expression. In astrocytes, APP and SREBP1 did not interact nor did APP affect cholesterol biosynthesis. Neuronal expression of APP decreased both HMGCR and cholesterol 24-hydroxylase mRNA levels and consequently cholesterol turnover, leading to inhibition of neuronal activity, which was rescued by geranylgeraniol, generated in the mevalonate pathway, in both APP expressing and mevastatin treated neurons. We conclude that APP controls cholesterol turnover needed for neuronal activity.

  2. A Small Potassium Current in AgRP/NPY Neurons Regulates Feeding Behavior and Energy Metabolism.

    PubMed

    He, Yanlin; Shu, Gang; Yang, Yongjie; Xu, Pingwen; Xia, Yan; Wang, Chunmei; Saito, Kenji; Hinton, Antentor; Yan, Xiaofeng; Liu, Chen; Wu, Qi; Tong, Qingchun; Xu, Yong

    2016-11-08

    Neurons that co-express agouti-related peptide (AgRP) and neuropeptide Y (NPY) are indispensable for normal feeding behavior. Firing activities of AgRP/NPY neurons are dynamically regulated by energy status and coordinate appropriate feeding behavior to meet nutritional demands. However, intrinsic mechanisms that regulate AgRP/NPY neural activities during the fed-to-fasted transition are not fully understood. We found that AgRP/NPY neurons in satiated mice express high levels of the small-conductance calcium-activated potassium channel 3 (SK3) and are inhibited by SK3-mediated potassium currents; on the other hand, food deprivation suppresses SK3 expression in AgRP/NPY neurons, and the decreased SK3-mediated currents contribute to fasting-induced activation of these neurons. Genetic mutation of SK3 specifically in AgRP/NPY neurons leads to increased sensitivity to diet-induced obesity, associated with chronic hyperphagia and decreased energy expenditure. Our results identify SK3 as a key intrinsic mediator that coordinates nutritional status with AgRP/NPY neural activities and animals' feeding behavior and energy metabolism.

  3. Bacteria activate sensory neurons that modulate pain and inflammation

    PubMed Central

    Chiu, Isaac M.; Heesters, Balthasar A.; Ghasemlou, Nader; Von Hehn, Christian A.; Zhao, Fan; Tran, Johnathan; Wainger, Brian; Strominger, Amanda; Muralidharan, Sriya; Horswill, Alexander R.; Wardenburg, Juliane Bubeck; Hwang, Sun Wook; Carroll, Michael C.; Woolf, Clifford J.

    2013-01-01

    Summary Nociceptor sensory neurons are specialized to detect potentially damaging stimuli, protecting the organism by initiating the sensation of pain and eliciting defensive behaviors. Bacterial infections produce pain by unknown molecular mechanisms, although they are presumed secondary to immune activation. Here we demonstrate that bacteria directly activate nociceptors, and that the immune response mediated through TLR2, MyD88, T cells, B cells, and neutrophils/monocytes is not necessary for Staphylococcus aureus induced pain in mice. Mechanical and thermal hyperalgesia parallels live bacterial load rather than tissue swelling or immune activation. Bacteria induce calcium flux and action potentials in nociceptor neurons, in part via bacterial N-formylated peptides and the pore-forming toxin alpha-hemolysin through distinct mechanisms. Specific ablation of Nav1.8-lineage neurons, which include nociceptors, abrogated pain during bacterial infection, but concurrently increased local immune infiltration and lymphadenopathy of the draining lymph node. Thus, bacterial pathogens produce pain by directly activating sensory neurons that modulate inflammation, an unsuspected role for the nervous system in host-pathogen interactions. PMID:23965627

  4. Theta Synchronizes the Activity of Medial Prefrontal Neurons during Learning

    ERIC Educational Resources Information Center

    Paz, Rony; Bauer, Elizabeth P.; Pare, Denis

    2008-01-01

    Memory consolidation is thought to involve the gradual transfer of transient hippocampal-dependent traces to distributed neocortical sites via the rhinal cortices. Recently, medial prefrontal (mPFC) neurons were shown to facilitate this process when their activity becomes synchronized. However, the mechanisms underlying this enhanced synchrony…

  5. Activating STAT3 Alpha for Promoting Healing of Neurons

    NASA Technical Reports Server (NTRS)

    Conway, Greg

    2008-01-01

    A method of promoting healing of injured or diseased neurons involves pharmacological activation of the STAT3 alpha protein. Usually, injured or diseased neurons heal incompletely or not at all for two reasons: (1) they are susceptible to apoptosis (cell death); and (2) they fail to engage in axogenesis that is, they fail to re-extend their axons to their original targets (e.g., muscles or other neurons) because of insufficiency of compounds, denoted neurotrophic factors, needed to stimulate such extension. The present method (see figure) of treatment takes advantage of prior research findings to the effect that the STAT3 alpha protein has anti-apoptotic and pro-axogenic properties.

  6. Dendritic integration in pyramidal neurons during network activity and disease.

    PubMed

    Palmer, Lucy M

    2014-04-01

    Neurons have intricate dendritic morphologies which come in an array of shapes and sizes. Not only do they give neurons their unique appearance, but dendrites also endow neurons with the ability to receive and transform synaptic inputs. We now have a wealth of information about the functioning of dendrites which suggests that the integration of synaptic inputs is highly dependent on both dendritic properties and neuronal input patterns. It has been shown that dendrites can perform non-linear processing, actively transforming synaptic input into Na(+) spikes, Ca(2+) plateau spikes and NMDA spikes. These membrane non-linearities can have a large impact on the neuronal output and have been shown to be regulated by numerous factors including synaptic inhibition. Many neuropathological diseases involve changes in how dendrites receive and package synaptic input by altering dendritic spine characteristics, ion channel expression and the inhibitory control of dendrites. This review focuses on the role of dendrites in integrating and transforming input and what goes wrong in the case of neuropathological diseases.

  7. Activity patterns of serotonin neurons underlying cognitive flexibility

    PubMed Central

    Matias, Sara; Lottem, Eran; Dugué, Guillaume P; Mainen, Zachary F

    2017-01-01

    Serotonin is implicated in mood and affective disorders. However, growing evidence suggests that a core endogenous role is to promote flexible adaptation to changes in the causal structure of the environment, through behavioral inhibition and enhanced plasticity. We used long-term photometric recordings in mice to study a population of dorsal raphe serotonin neurons, whose activity we could link to normal reversal learning using pharmacogenetics. We found that these neurons are activated by both positive and negative prediction errors, and thus report signals similar to those proposed to promote learning in conditions of uncertainty. Furthermore, by comparing the cue responses of serotonin and dopamine neurons, we found differences in learning rates that could explain the importance of serotonin in inhibiting perseverative responding. Our findings show how the activity patterns of serotonin neurons support a role in cognitive flexibility, and suggest a revised model of dopamine–serotonin opponency with potential clinical implications. DOI: http://dx.doi.org/10.7554/eLife.20552.001 PMID:28322190

  8. Microglial activation induces neuronal death in Chandipura virus infection

    PubMed Central

    Verma, Abhishek Kumar; Ghosh, Sourish; Pradhan, Sreeparna; Basu, Anirban

    2016-01-01

    Neurotropic viruses induce neurodegeneration either directly by activating host death domains or indirectly through host immune response pathways. Chandipura Virus (CHPV) belonging to family Rhabdoviridae is ranked among the emerging pathogens of the Indian subcontinent. Previously we have reported that CHPV induces neurodegeneration albeit the root cause of this degeneration is still an open question. In this study we explored the role of microglia following CHPV infection. Phenotypic analysis of microglia through lectin and Iba-1 staining indicated cells were in an activated state post CHPV infection in cortical region of the infected mouse brain. Cytokine Bead Array (CBA) analysis revealed comparatively higher cytokine and chemokine levels in the same region. Increased level of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), Nitric Oxide (NO) and Reactive Oxygen species (ROS) in CHPV infected mouse brain indicated a strong inflammatory response to CHPV infection. Hence it was hypothesized through our analyses that this inflammatory response may stimulate the neuronal death following CHPV infection. In order to validate our hypothesis supernatant from CHPV infected microglial culture was used to infect neuronal cell line and primary neurons. This study confirmed the bystander killing of neurons due to activation of microglia post CHPV infection. PMID:26931456

  9. Hypoglycemia-activated K+ channels in hippocampal neurons.

    PubMed

    Tromba, C; Salvaggio, A; Racagni, G; Volterra, A

    1992-08-31

    Channels linking the electrical and metabolic activities of cells (KATP channels) have been described in various tissues, including some brain areas (hypothalamus, cerebral cortex and substantia nigra). Here we report the existence in hippocampal neurons of K+ permeant channels whose activity is regulated by extracellular glucose. They are open at the cell resting potential and respond to transient hypoglycemia with a reversible increase in activity. The one type so far characterized has a conductance of approximately 100 pS in isotonic K+, is inhibited by the sulphonylurea glibenclamide (1 microM), and is activated by the potassium channel opener lemakalim (0.1-1 microM). These data provide a direct demonstration of the presence, in hippocampal neurons, of glucose-sensitive channels that could belong to the KATP family.

  10. Cable theory in neurons with active, linearized membranes.

    PubMed

    Koch, C

    1984-01-01

    This investigation aims at exploring some of the functional consequences of single neurons containing active, voltage dependent channels for information processing. Assuming that the voltage change in the dendritic tree of these neurons does not exceed a few millivolts, it is possible to linearize the non-linear channel conductance. The membrane can then be described in terms of resistances, capacitances and inductances, as for instance in the small-signal analysis of the squid giant axon. Depending on the channel kinetics and the associated ionic battery the linearization yields two basic types of membrane: a membrane modeled by a collection of resistances and capacitances and membranes containing in addition to these components inductances. Under certain specified conditions the latter type of membrane gives rise to a membrane impedance that displays a prominent maximum at some nonzero resonant frequency fmax. We call this type of membrane quasi-active, setting it apart from the usual passive membrane. We study the linearized behaviour of active channels giving rise to quasi-active membranes in extended neuronal structures and consider several instances where such membranes may subserve neuronal function: 1. The resonant frequency of a quasi-active membrane increases with increasing density of active channels. This might be one of the biophysical mechanisms generating the large range over which hair cells in the vertebrate cochlea display frequency tuning. 2. The voltage recorded from a cable with a quasi-active membrane can be proportional to the temporal derivative of the injected current. 3. We modeled a highly branched dendritic tree (delta-ganglion cell of the cat retina) using a quasi-active membrane. The voltage attenuation from a given synaptic site to the soma decreases with increasing frequency up to the resonant frequency, in sharp contrast to the behaviour of passive membranes.(ABSTRACT TRUNCATED AT 400 WORDS)

  11. Nitrergic ventro-medial medullary neurons activated during cholinergically induced active (REM) sleep in the cat

    PubMed Central

    Pose, Inés; Sampogna, Sharon; Chase, Michael H.; Morales, Francisco R.

    2010-01-01

    The rostral ventro-medial medullary reticular formation is a complex structure that is involved with a variety of motor functions. It contains glycinergic neurons that are activated during active (REM) sleep (AS); these neurons appear to be responsible for the postsynaptic inhibition of motoneurons that occurs during this state. We have reported that neurons in this same region contain nitric oxide (NO) synthase and that they innervate brainstem motor pools. In the present study we examined the c-fos expression of these neurons after carbachol-induced active sleep (C-AS). Three control and four experimental cats were employed to identify c-fos expressing nitrergic neurons using immunocytochemical techniques to detect the Fos protein together with neuronal nitric oxide synthase (nNOS) or NADPH-diaphorase activity. The classical neurotransmitter content of the nitrergic cells in this region was examined through the combination of immunocytochemical techniques for the detection of glutamate, glycine, choline acetyltransferase (ChAT), tyrosine hydroxilase (TH) or GABA together with nNOS. During C-AS, there was a 1074% increase in the number of nitrergic neurons that expressed c-fos. These neurons did not contain glycine, ChAT, TH or GABA, but a subpopulation (15%) of them displayed glutamate-like immunoreactivity. Therefore, some of these neurons contain both an excitatory neurotransmitter (glutamate) and an excitatory neuromodulator (NO); the neurotransmitter content of the rest of them remains to be determined. Because some of the nitrergic neurons innervate brainstem motoneurons it is possible that they participate in the generation of tonic and excitatory phasic motor events that occur during AS. We also suggest that these nitrergic neurons may be involved in autonomic regulation during this state. In addition, because NO has trophic effects on target neurons, the present findings represent the first, albeit indirect, evidence for a possible trophic function of

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

    PubMed

    Herculano-Houzel, Suzana

    2011-03-01

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

  13. Neuronal activity promotes myelination via a cAMP pathway.

    PubMed

    Malone, Misti; Gary, Devin; Yang, In Hong; Miglioretti, Anna; Houdayer, Thierry; Thakor, Nitish; McDonald, John

    2013-06-01

    Neuronal activity promotes myelination in vivo and in vitro. However, the molecular events that mediate activity-dependent myelination are not completely understood. Seven, daily 1 h sessions of patterned electrical stimulation (ESTIM) promoted myelin segment formation in mixed cultures of dorsal root ganglion (DRG) neurons and oligodendrocytes (OLs); the increase in myelination was frequency-dependent. Myelin segment formation was also enhanced following exposure of DRGs to ESTIM prior to OL addition, suggesting that ESTIM promotes myelination in a manner involving neuron-specific signaling. Cyclic adenosine monophosphate (cAMP) levels in DRGs were increased three-fold following ESTIM, and artificially increasing cAMP mimicked the ability of ESTIM to promote myelination. Alternatively, inhibiting the cAMP pathway suppressed ESTIM-induced myelination. We used compartmentalized, microfluidic platforms to isolate DRG soma from OLs and assessed cell-type specific effects of ESTIM on myelination. A selective increase or decrease in DRG cAMP levels resulted in enhanced or suppressed myelination, respectively. This work describes a novel role for the cAMP pathway in neurons that results in enhanced myelination.

  14. Beyond Statistical Significance: Implications of Network Structure on Neuronal Activity

    PubMed Central

    Vlachos, Ioannis; Aertsen, Ad; Kumar, Arvind

    2012-01-01

    It is a common and good practice in experimental sciences to assess the statistical significance of measured outcomes. For this, the probability of obtaining the actual results is estimated under the assumption of an appropriately chosen null-hypothesis. If this probability is smaller than some threshold, the results are deemed statistically significant and the researchers are content in having revealed, within their own experimental domain, a “surprising” anomaly, possibly indicative of a hitherto hidden fragment of the underlying “ground-truth”. What is often neglected, though, is the actual importance of these experimental outcomes for understanding the system under investigation. We illustrate this point by giving practical and intuitive examples from the field of systems neuroscience. Specifically, we use the notion of embeddedness to quantify the impact of a neuron's activity on its downstream neurons in the network. We show that the network response strongly depends on the embeddedness of stimulated neurons and that embeddedness is a key determinant of the importance of neuronal activity on local and downstream processing. We extrapolate these results to other fields in which networks are used as a theoretical framework. PMID:22291581

  15. Insulin-Dependent Activation of MCH Neurons Impairs Locomotor Activity and Insulin Sensitivity in Obesity.

    PubMed

    Hausen, A Christine; Ruud, Johan; Jiang, Hong; Hess, Simon; Varbanov, Hristo; Kloppenburg, Peter; Brüning, Jens C

    2016-12-06

    Melanin-concentrating-hormone (MCH)-expressing neurons (MCH neurons) in the lateral hypothalamus (LH) are critical regulators of energy and glucose homeostasis. Here, we demonstrate that insulin increases the excitability of these neurons in control mice. In vivo, insulin promotes phosphatidylinositol 3-kinase (PI3K) signaling in MCH neurons, and cell-type-specific deletion of the insulin receptor (IR) abrogates this response. While lean mice lacking the IR in MCH neurons (IR(ΔMCH)) exhibit no detectable metabolic phenotype under normal diet feeding, they present with improved locomotor activity and insulin sensitivity under high-fat-diet-fed, obese conditions. Similarly, obesity promotes PI3 kinase signaling in these neurons, and this response is abrogated in IR(ΔMCH) mice. In turn, acute chemogenetic activation of MCH neurons impairs locomotor activity but not insulin sensitivity. Collectively, our experiments reveal an insulin-dependent activation of MCH neurons in obesity, which contributes via distinct mechanisms to the manifestation of impaired locomotor activity and insulin resistance.

  16. Optogenetic activation of serotonergic terminals facilitates GABAergic inhibitory input to orexin/hypocretin neurons

    PubMed Central

    Chowdhury, Srikanta; Yamanaka, Akihiro

    2016-01-01

    Orexin/hypocretin neurons play a crucial role in the regulation of sleep/wakefulness, primarily in the maintenance of wakefulness. These neurons innervate wide areas of the brain and receive diverse synaptic inputs including those from serotonergic (5-HT) neurons in the raphe nucleus. Previously we showed that pharmacological application of 5-HT directly inhibited orexin neurons via 5-HT1A receptors. However, it was still unclear how 5-HT neurons regulated orexin neurons since 5-HT neurons contain not only 5-HT but also other neurotransmitters. To reveal this, we generated new triple transgenic mice in which orexin neurons express enhanced green fluorescent protein (EGFP) and 5-HT neurons express channelrhodopsin2 (ChR2). Immunohistochemical studies show that nerve endings of ChR2-expressing 5-HT neurons are in close apposition to EGFP-expressing orexin neurons in the lateral hypothalamic area. Using these mice, we could optogenetically activate 5-HT nerve terminals and record postsynaptic effects from orexin neurons. Activation of nerve terminals of 5-HT neurons directly inhibited orexin neurons via the 5HT1A receptor, and also indirectly inhibited orexin neurons by facilitating GABAergic inhibitory inputs without affecting glutamatergic inputs. Increased GABAergic inhibitory inputs in orexin neurons were confirmed by the pharmacological application of 5-HT. These results suggest that orexin neurons are inhibited by 5-HT neurons, primarily via 5-HT, in both direct and indirect manners. PMID:27824065

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

    PubMed

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

    2014-04-08

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

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

    ERIC Educational Resources Information Center

    Wilson, Yvette M.; Murphy, Mark

    2009-01-01

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

  19. Activity of Protease-Activated Receptors in Primary Cultured Human Myenteric Neurons

    PubMed Central

    Kugler, Eva M.; Mazzuoli, Gemma; Demir, Ihsan E.; Ceyhan, Güralp O.; Zeller, Florian; Schemann, Michael

    2012-01-01

    Activity of the four known protease-activated receptors (PARs) has been well studied in rodent enteric nervous system and results in animal models established an important role for neuronal PAR2. We recently demonstrated that, unlike in rodents, PAR1 is the dominant neuronal protease receptor in the human submucous plexus. With this study we investigated whether this also applies to the human myenteric plexus. We used voltage sensitive dye recordings to detect action potential discharge in primary cultures of human myenteric neurons in response to PAR activating peptides (APs). Application of the PAR1-AP (TFLLR) or PAR4-AP (GYPGQV) evoked spike discharge in 79 or 23% of myenteric neurons, respectively. The PAR1-AP response was mimicked by the endogenous PAR1 activator thrombin and blocked by the PAR1 antagonists SCH79797. Human myenteric neurons did not respond to PAR2-AP. This was not due to culture conditions because all three PAR-APs evoked action potentials in cultured guinea pig myenteric neurons. Consecutive application of PAR-APs revealed coexpression (relative to the population responding to PAR-APs) of PAR1/PAR2 in 51%, PAR1/PAR4 in 43%, and of PAR2/PAR4 in 29% of guinea pig myenteric neurons. Our study provided further evidence for the prominent role of neuronal PAR1 in the human enteric nervous system. PMID:22988431

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

    PubMed Central

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

    2013-01-01

    SUMMARY Targeting genetically encoded tools for neural circuit dissection to relevant cellular populations is a major challenge in neurobiology. We developed a new approach, Targeted Recombination in Active Populations (TRAP), to obtain genetic access to neurons that were activated by defined stimuli. This method utilizes mice in which the tamoxifen-dependent recombinase CreERT2 is expressed in an activity-dependent manner from the loci of the immediate early genes Arc and Fos. Active cells that express CreERT2 can undergo recombination only when tamoxifen is present, allowing genetic access to neurons that are active during a time window of less than 12 h. We show that TRAP can selectively provide access to neurons activated by specific somatosensory, visual, and auditory stimuli, and by experience in a novel environment. When combined with tools for labeling, tracing, recording, and manipulating neurons, TRAP offers a powerful new approach for understanding how the brain processes information and generates behavior. PMID:23764283

  1. Linking neuronal brain activity to the glucose metabolism

    PubMed Central

    2013-01-01

    Background Energy homeostasis ensures the functionality of the entire organism. The human brain as a missing link in the global regulation of the complex whole body energy metabolism is subject to recent investigation. The goal of this study is to gain insight into the influence of neuronal brain activity on cerebral and peripheral energy metabolism. In particular, the tight link between brain energy supply and metabolic responses of the organism is of interest. We aim to identifying regulatory elements of the human brain in the whole body energy homeostasis. Methods First, we introduce a general mathematical model describing the human whole body energy metabolism. It takes into account the two central roles of the brain in terms of energy metabolism. The brain is considered as energy consumer as well as regulatory instance. Secondly, we validate our mathematical model by experimental data. Cerebral high-energy phosphate content and peripheral glucose metabolism are measured in healthy men upon neuronal activation induced by transcranial direct current stimulation versus sham stimulation. By parameter estimation we identify model parameters that provide insight into underlying neurophysiological processes. Identified parameters reveal effects of neuronal activity on regulatory mechanisms of systemic glucose metabolism. Results Our examinations support the view that the brain increases its glucose supply upon neuronal activation. The results indicate that the brain supplies itself with energy according to its needs, and preeminence of cerebral energy supply is reflected. This mechanism ensures balanced cerebral energy homeostasis. Conclusions The hypothesis of the central role of the brain in whole body energy homeostasis as active controller is supported. PMID:23988084

  2. Role of BDNF epigenetics in activity-dependent neuronal plasticity.

    PubMed

    Karpova, Nina N

    2014-01-01

    Brain-derived neurotrophic factor (BDNF) is a key mediator of the activity-dependent processes in the brain that have a major impact on neuronal development and plasticity. Impaired control of neuronal activity-induced BDNF expression mediates the pathogenesis of various neurological and psychiatric disorders. Different environmental stimuli, such as the use of pharmacological compounds, physical and learning exercises or stress exposure, lead to activation of specific neuronal networks. These processes entail tight temporal and spatial transcriptional control of numerous BDNF splice variants through epigenetic mechanisms. The present review highlights recent findings on the dynamic and long-term epigenetic programming of BDNF gene expression by the DNA methylation, histone-modifying and microRNA machineries. The review also summarizes the current knowledge on the activity-dependent BDNF mRNA trafficking critical for rapid local regulation of BDNF levels and synaptic plasticity. Current data open novel directions for discovery of new promising therapeutic targets for treatment of neuropsychiatric disorders. This article is part of the Special Issue entitled 'BDNF Regulation of Synaptic Structure, Function, and Plasticity'.

  3. Neuronal Activity Regulates Hippocampal miRNA Expression

    PubMed Central

    Eacker, Stephen M.; Keuss, Matthew J.; Berezikov, Eugene; Dawson, Valina L.; Dawson, Ted M.

    2011-01-01

    Neuronal activity regulates a broad range of processes in the hippocampus, including the precise regulation of translation. Disruptions in proper translational control in the nervous system are associated with a variety of disorders that fall in the autistic spectrum. MicroRNA (miRNA) represent a relatively recently discovered player in the regulation of translation in the nervous system. We have conducted an in depth analysis of how neuronal activity regulates miRNA expression in the hippocampus. Using deep sequencing we exhaustively identify all miRNAs, including 15 novel miRNAs, expressed in hippocampus of the adult mouse. We identified 119 miRNAs documented in miRBase but less than half of these miRNA were expressed at a level greater than 0.1% of total miRNA. Expression profiling following induction of neuronal activity by electroconvulsive shock demonstrates that most miRNA show a biphasic pattern of expression: rapid induction of specific mature miRNA expression followed by a decline in expression. These results have important implications into how miRNAs influence activity-dependent translational control. PMID:21984899

  4. Neuronal activity controls Bdnf expression via Polycomb de-repression and CREB/CBP/JMJD3 activation in mature neurons

    PubMed Central

    Palomer, Ernest; Carretero, Javier; Benvegnù, Stefano; Dotti, Carlos G.; Martin, Mauricio G.

    2016-01-01

    It has been recently described that in embryonic stem cells, the expression of some important developmentally regulated genes is repressed, but poised for fast activation under the appropriate stimuli. In this work we show that Bdnf promoters are repressed by Polycomb Complex 2 in mature hippocampal neurons, and basal expression is guaranteed by the coexistence with activating histone marks. Neuronal stimulation triggered by N-methyl-D-aspartate application induces the transcription of these promoters by H3K27Me3 demethylation and H3K27Me3 phosphorylation at Serine 28 leading to displacement of EZH2, the catalytic subunit of Polycomb Repressor Complex 2. Our data show that the fast transient expression of Bdnf promoters II and VI after neuronal stimulation is dependent on acetylation of histone H3K27 by CREB-p/CBP. Thus, regulatory mechanisms established during development seem to remain after differentiation controlling genes induced by different stimuli, as would be the case of early memory genes in mature neurons. PMID:27010597

  5. Behavioral State Modulates the Activity of Brainstem Sensorimotor Neurons

    PubMed Central

    McArthur, Kimberly L.

    2011-01-01

    Sensorimotor processing must be modulated according to the animal's behavioral state. A previous study demonstrated that motion responses were strongly state dependent in birds. Vestibular eye and head responses were significantly larger and more compensatory during simulated flight, and a flight-specific vestibular tail response was also characterized. In the current study, we investigated the neural substrates for these state-dependent vestibular behaviors by recording extracellularly from neurons in the vestibular nuclear complex and comparing their spontaneous activity and sensory responses during default and simulated flight states. We show that motion-sensitive neurons in the lateral vestibular nucleus are state dependent. Some neurons increased their spontaneous firing rates during flight, though their increased excitability was not reflected in higher sensory gains. However, other neurons exhibited state-dependent gating of sensory inputs, responding to rotational stimuli only during flight. These results demonstrate that vestibular processing in the brainstem is state dependent and lay the foundation for future studies to investigate the synaptic mechanisms responsible for these modifications. PMID:22090497

  6. Activity-Dependent Neuronal Model on Complex Networks

    PubMed Central

    de Arcangelis, Lucilla; Herrmann, Hans J.

    2012-01-01

    Neuronal avalanches are a novel mode of activity in neuronal networks, experimentally found in vitro and in vivo, and exhibit a robust critical behavior: these avalanches are characterized by a power law distribution for the size and duration, features found in other problems in the context of the physics of complex systems. We present a recent model inspired in self-organized criticality, which consists of an electrical network with threshold firing, refractory period, and activity-dependent synaptic plasticity. The model reproduces the critical behavior of the distribution of avalanche sizes and durations measured experimentally. Moreover, the power spectra of the electrical signal reproduce very robustly the power law behavior found in human electroencephalogram (EEG) spectra. We implement this model on a variety of complex networks, i.e., regular, small-world, and scale-free and verify the robustness of the critical behavior. PMID:22470347

  7. Nutritional state-dependent ghrelin activation of vasopressin neurons via retrograde trans-neuronal-glial stimulation of excitatory GABA circuits.

    PubMed

    Haam, Juhee; Halmos, Katalin C; Di, Shi; Tasker, Jeffrey G

    2014-04-30

    Behavioral and physiological coupling between energy balance and fluid homeostasis is critical for survival. The orexigenic hormone ghrelin has been shown to stimulate the secretion of the osmoregulatory hormone vasopressin (VP), linking nutritional status to the control of blood osmolality, although the mechanism of this systemic crosstalk is unknown. Here, we show using electrophysiological recordings and calcium imaging in rat brain slices that ghrelin stimulates VP neurons in the hypothalamic paraventricular nucleus (PVN) in a nutritional state-dependent manner by activating an excitatory GABAergic synaptic input via a retrograde neuronal-glial circuit. In slices from fasted rats, ghrelin activation of a postsynaptic ghrelin receptor, the growth hormone secretagogue receptor type 1a (GHS-R1a), in VP neurons caused the dendritic release of VP, which stimulated astrocytes to release the gliotransmitter adenosine triphosphate (ATP). ATP activation of P2X receptors excited presynaptic GABA neurons to increase GABA release, which was excitatory to the VP neurons. This trans-neuronal-glial retrograde circuit activated by ghrelin provides an alternative means of stimulation of VP release and represents a novel mechanism of neuronal control by local neuronal-glial circuits. It also provides a potential cellular mechanism for the physiological integration of energy and fluid homeostasis.

  8. Manipulating neuronal activity with low frequency transcranial ultrasound

    NASA Astrophysics Data System (ADS)

    Moore, Michele Elizabeth

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

  9. New neurons generated from running are broadly recruited into neuronal activation associated with three different hippocampus-involved tasks.

    PubMed

    Clark, Peter J; Bhattacharya, Tushar K; Miller, Daniel S; Kohman, Rachel A; DeYoung, Erin K; Rhodes, Justin S

    2012-09-01

    Running increases the formation of new neurons in the adult rodent hippocampus. However, the function of new neurons generated from running is currently unknown. One hypothesis is that new neurons from running contribute to enhanced cognitive function by increasing plasticity in the adult hippocampus. An alternative hypothesis is that new neurons generated from running incorporate into experience-specific hippocampal networks that only become active during running. The purpose of this experiment was to determine if new neurons generated from running are selectively activated by running, or can become recruited into granule cell activity occurring during performance on other behavioral tasks that engage the hippocampus. Therefore, the activation of new 5-6 week neurons was detected using BrdU, NeuN, and Zif268 triple-label immunohistochemistry in cohorts of female running and sedentary adult C57BL/6J mice following participation in one of three different tasks: the Morris water maze, novel environment exploration, or wheel running. Results showed that running and sedentary mice displayed a nearly equivalent proportion of new neurons that expressed Zif268 following each task. Since running approximately doubled the number of new neurons, the results demonstrated that running mice had a greater number of new neurons recruited into the Zif268 induction in the granule cell layer following each task than sedentary mice. The results suggest that new neurons incorporated into hippocampal circuitry from running are not just activated by wheel running itself, but rather become broadly recruited into granule cell layer activity during distinct behavioral experiences.

  10. Circadian Neuron Feedback Controls the Drosophila Sleep-Activity Profile

    PubMed Central

    Guo, Fang; Yu, Junwei; Jung, Hyung Jae; Abruzzi, Katharine C.; Luo, Weifei; Griffith, Leslie C.; Rosbash, Michael

    2016-01-01

    SUMMARY Little is known about the ability of Drosophila circadian neurons to promote sleep. We show here with optogenetic manipulations and video recording that a subset of dorsal clock neurons (DN1s) are potent sleep-promoting cells, releasing glutamate to directly inhibit key pacemaker neurons. These pacemakers promote morning arousal by activating these same DN1s, implying that there is a late-day feedback circuit to drive siesta and nighttime sleep. To address more plastic aspects of the sleep program, we used a novel calcium assay to monitor and compared the real-time DN1 activity of freely behaving males and females. It revealed a dramatic sexual dimorphism, which parallels the well-known difference in daytime sleep. DN1 activity is also enhanced by elevated temperature, consistent with its known effect on sleep. These new approaches indicate that the DN1s have a major impact on the fly sleep-wake profile and integrate environmental information with the circadian molecular program. PMID:27479324

  11. Casein Kinase 1 Suppresses Activation of REST in Insulted Hippocampal Neurons and Halts Ischemia-Induced Neuronal Death

    PubMed Central

    Kaneko, Naoki; Hwang, Jee-Yeon; Gertner, Michael; Pontarelli, Fabrizio

    2014-01-01

    Repressor Element-1 (RE1) Silencing Transcription Factor/Neuron-Restrictive Silencer Factor (REST/NRSF) is a gene-silencing factor that is widely expressed during embryogenesis and plays a strategic role in neuronal differentiation. Recent studies indicate that REST can be activated in differentiated neurons during a critical window of time in postnatal development and in adult neurons in response to neuronal insults such as seizures and ischemia. However, the mechanism by which REST is regulated in neurons is as yet unknown. Here, we show that REST is controlled at the level of protein stability via β-TrCP-dependent, ubiquitin-based proteasomal degradation in differentiated neurons under physiological conditions and identify Casein Kinase 1 (CK1) as an upstream effector that bidirectionally regulates REST cellular abundance. CK1 associates with and phosphorylates REST at two neighboring, but distinct, motifs within the C terminus of REST critical for binding of β-TrCP and targeting of REST for proteasomal degradation. We further show that global ischemia in rats in vivo triggers a decrease in CK1 and an increase in REST in selectively vulnerable hippocampal CA1 neurons. Administration of the CK1 activator pyrvinium pamoate by in vivo injection immediately after ischemia restores CK1 activity, suppresses REST expression, and rescues neurons destined to die. Our results identify a novel and previously unappreciated role for CK1 as a brake on REST stability and abundance in adult neurons and reveal that loss of CK1 is causally related to ischemia-induced neuronal death. These findings point to CK1 as a potential therapeutic target for the amelioration of hippocampal injury and cognitive deficits associated with global ischemia. PMID:24760862

  12. Cloning of three novel neuronal Cdk5 activator binding proteins.

    PubMed

    Ching, Y P; Qi, Z; Wang, J H

    2000-01-25

    Neuronal Cdc2-like kinase (Nclk) is involved in the regulation of neuronal differentiation and neuro-cytoskeleton dynamics. The active kinase consists of a catalytic subunit, Cdk5, and a 25 kDa activator protein (p25nck5a) derived from a 35 kDa neuronal-specific protein (p35nck5a). As an extension of our previous study (Qi, Z., Tang, D., Zhu, X., Fujita, D.J., Wang, J.H., 1998. Association of neurofilament proteins with neuronal Cdk5 activator. J. Biol. Chem. 270, 2329-2335), which showed that neurofilament is one of the p35nck5a-associated proteins, we now report the isolation of three other novel p35nck5a-associated proteins using the yeast two-hybrid screen. The full-length forms of these three novel proteins, designated C42, C48 and C53, have a molecular mass of 66, 24, and 57 kDa, respectively. Northern analysis indicates that these novel proteins are widely expressed in human tissues, including the heart, brain, skeletal muscle, placenta, lung, liver, kidney and pancreas. The bacterially expressed glutathione S-transferase (GST)-fusion forms of these three proteins were able to co-precipitate p35nck5a complexed with Cdk5 from insect cell lysate. Among these three proteins, only C48 and C53 can be phosphorylated by Nclk, suggesting that they may be the substrates of Nclk. Sequence homology searches have suggested that the C48 protein is marginally related to restin protein, whereas the C42 protein has homologues of unknown function in Caenorhabditis elegans and Arabidopsis thaliana.

  13. Characterization, tissue distribution, and regulation of agouti-related protein (AgRP), cocaine- and amphetamine-regulated transcript (CART) and neuropeptide Y (NPY) in Atlantic salmon (Salmo salar).

    PubMed

    Murashita, Koji; Kurokawa, Tadahide; Ebbesson, Lars O E; Stefansson, Sigurd O; Rønnestad, Ivar

    2009-06-01

    Key peptide hormones involved in the control of appetite in vertebrates were identified, their genes characterized and their regulation studied in Atlantic salmon: two agouti-related proteins (AgRP), cocaine- and amphetamine-regulated transcript (CART) and neuropeptide Y (NPY). The AgRP-1 and AgRP-2 genes encode prepro-proteins of 142- and 117-amino acids, respectively. The deduced AgRP-2 protein has 10 cysteine residues in the C-terminal polycysteine domain, while the AgRP-1 lacks the 6th and 7th cysteine residues observed in other species. AgRP-1 was principally expressed in the pituitary and skin, while AgRP-2 was highly expressed in the mid-gut, red muscle and gonads. The CART gene, encoding 118-amino acids, was strongly expressed in the brain and eye. In addition to salmon CART, we identified three to six variants of the CART gene in lower vertebrates by mining available databases. The salmon NPY gene, encoding 100-amino acids, was mainly expressed in the brain and eye. AgRP-1 and CART mRNA levels in the brain decreased after 6 days of fasting while AgRP-2 and NPY showed no significant change, suggesting that AgRP-1 and CART are involved in feeding regulation in Atlantic salmon. The identification of multiple variants of these appetite-regulating genes emphasizes the importance to further investigate the complex regulation of these genes.

  14. Parthanatos Mediates AIMP2 Activated Age Dependent Dopaminergic Neuronal Loss

    PubMed Central

    Lee, Yunjong; Karuppagounder, Senthilkumar S.; Shin, Joo-Ho; Lee, Yun-Il; Ko, Han Seok; Swing, Debbie; Jiang, Haisong; Kang, Sung-Ung; Lee, Byoung Dae; Kang, Ho Chul; Kim, Donghoon; Tessarollo, Lino; Dawson, Valina L.; Dawson, Ted M.

    2013-01-01

    The defining pathogenic feature of Parkinson’s disease is the age dependent loss of dopaminergic neurons. Mutations and inactivation of parkin, an ubiquitin E3 ligase, cause Parkinson’s disease through accumulation of pathogenic substrates. Here we show that transgenic overexpression of the parkin substrate, aminoacyl-tRNA synthetase complex interacting multifunctional protein-2 (AIMP2) leads to a selective, age-dependent progressive loss of dopaminergic neurons via activation of poly(ADP-ribose) polymerase-1 (PARP1). AIMP2 accumulation in vitro and in vivo results in PARP1 overactivation and dopaminergic cell toxicity via direct association of these proteins in the nucleus providing a new path to PARP1 activation other than DNA damage. Inhibition of PARP1 through gene deletion or drug inhibition reverses behavioral deficits and protects in vivo against dopamine neuron death in AIMP2 transgenic mice. These data indicate that brain permeable PARP inhibitors could be effective in delaying or preventing disease progression in Parkinson’s disease. PMID:23974709

  15. Activation of Brainstem Neurons by Underwater Diving in the Rat

    PubMed Central

    Panneton, W. Michael; Gan, Qi; Le, Jason; Livergood, Robert S.; Clerc, Philip; Juric, Rajko

    2012-01-01

    The mammalian diving response is a powerful autonomic adjustment to underwater submersion greatly affecting heart rate, arterial blood pressure, and ventilation. The bradycardia is mediated by the parasympathetic nervous system, arterial blood pressure is mediated via the sympathetic system and still other circuits mediate the respiratory changes. In the present study we investigate the cardiorespiratory responses and the brainstem neurons activated by voluntary diving of trained rats, and, compare them to control and swimming animals which did not dive. We show that the bradycardia and increase in arterial blood pressure induced by diving were significantly different than that induced by swimming. Neuronal activation was calculated after immunohistochemical processing of brainstem sections for Fos protein. Labeled neurons were counted in the caudal pressor area, the medullary dorsal horn, subnuclei of the nucleus tractus solitarii (NTS), the nucleus raphe pallidus (RPa), the rostroventrolateral medulla, the A5 area, the nucleus locus coeruleus, the Kölliker–Fuse area, and the external lateral and superior lateral subnuclei of the parabrachial nucleus. All these areas showed significant increases in Fos labeling when data from voluntary diving rats were compared to control rats and all but the commissural subnucleus of the NTS, A5 area, and RPa were significantly different from swimming rats. These data provide a substrate for more precise experiments to determine the role of these nuclei in the reflex circuits driving the diving response. PMID:22563319

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

    PubMed Central

    Takeda, Mamoru; Takehana, Shiori; Sekiguchi, Kenta; Kubota, Yoshiko; Shimazu, Yoshihito

    2016-01-01

    Changes to somatic sensory pathways caused by peripheral tissue, inflammation or injury can result in behavioral hypersensitivity and pathological pain, such as hyperalgesia. Resveratrol, a plant polyphenol found in red wine and various food products, is known to have several beneficial biological actions. Recent reports indicate that resveratrol can modulate neuronal excitability, including nociceptive sensory transmission. As such, it is possible that this dietary constituent could be a complementary alternative medicine (CAM) candidate, specifically a therapeutic agent. The focus of this review is on the mechanisms underlying the modulatory effects of resveratrol on nociceptive neuronal activity associated with pain relief. In addition, we discuss the contribution of resveratrol to the relief of nociceptive and/or pathological pain and its potential role as a functional food and a CAM. PMID:27727178

  17. Activation of protease activated receptor 1 increases the excitability of the dentate granule neurons of hippocampus

    PubMed Central

    2011-01-01

    Protease activated receptor-1 (PAR1) is expressed in multiple cell types in the CNS, with the most prominent expression in glial cells. PAR1 activation enhances excitatory synaptic transmission secondary to the release of glutamate from astrocytes following activation of astrocytically-expressed PAR1. In addition, PAR1 activation exacerbates neuronal damage in multiple in vivo models of brain injury in a manner that is dependent on NMDA receptors. In the hippocampal formation, PAR1 mRNA appears to be expressed by a subset of neurons, including granule cells in the dentate gyrus. In this study we investigate the role of PAR activation in controlling neuronal excitability of dentate granule cells. We confirm that PAR1 protein is expressed in neurons of the dentate cell body layer as well as in astrocytes throughout the dentate. Activation of PAR1 receptors by the selective peptide agonist TFLLR increased the intracellular Ca2+ concentration in a subset of acutely dissociated dentate neurons as well as non-neuronal cells. Bath application of TFLLR in acute hippocampal slices depolarized the dentate gyrus, including the hilar region in wild type but not in the PAR1-/- mice. PAR1 activation increased the frequency of action potential generation in a subset of dentate granule neurons; cells in which PAR1 activation triggered action potentials showed a significant depolarization. The activation of PAR1 by thrombin increased the amplitude of NMDA receptor-mediated component of EPSPs. These data suggest that activation of PAR1 during normal function or pathological conditions, such as during ischemia or hemorrhage, can increase the excitability of dentate granule cells. PMID:21827709

  18. Effects of naltrexone on firing activity of rat cortex neurons and its interactions with ethanol.

    PubMed

    Kozhechkin, S N; Mednikova, Yu S; Kolik, L G

    2013-09-01

    Naltrexone dose-dependently decreased neuron firing rate in the rat frontal cortex after intravenous (1-20 mg/kg) and microelectrophoretic administration. Microelectrophoretic applications of naltrexone reduced the excitatory neuronal response of neurons to low doses of ethanol (electroosmotic application) and potentiated depression of firing activity induced by ethanol in high doses. We concluded that opioid peptides take part in generation of spontaneous neuronal activity in the frontal cortex and neuronal excitation caused by ethanol in low doses. Naltrexone acts as a synergist of ethanol in its depressive effect on cortical neurons.

  19. Linear and non-linear fluorescence imaging of neuronal activity

    NASA Astrophysics Data System (ADS)

    Fisher, Jonathan A. N.

    Optical imaging of neuronal activity offers new possibilities for understanding brain physiology. The predominant methods in neuroscience for measuring electrical activity require electrodes inserted into the tissue. Such methods, however, provide limited spatial information and are invasive. Optical methods are less physically invasive and offer the possibility for simultaneously imaging the activity of many neurons. In this thesis one- and two-photon fluorescence microscopy techniques were applied to several in vivo and in vitro mammalian preparations. Using one-photon absorption fluorescence microscopy and gradient index (GRIN) lens optics, cortical electrical activity in response to electric stimulation was resolved in three-dimensions at high-speed in the primary somatosensory cortex of the mouse in vivo using voltage-sensitive dyes. Imaging at depths up to 150 mum below the cortex surface, it was possible to resolve depth-dependent patterns of neuronal activity in response to cortical and thalamic electric stimulation. The patterns of activity were consistent with known cortical cellular architecture. In a qualitatively different set of experiments, one-photon fluorescence microscopy via voltage-sensitive dyes was successfully employed to image an in vitro preparation of the perfused rat brainstem during the process of respiratory rhythmogenesis. Imaging results yielded insights into the spatial organization of the central respiratory rhythm generation region in the ventrolateral medulla. A multifocal two-photon scanning microscope was constructed, and design and operation principles are described. Utilizing the novel device, anatomical and functional two-photon imaging via potentiometric dyes and calcium dyes is described, and the results of in vivo versus in vitro imaging are compared. Anatomical imaging results used either functional probe background fluorescence or green fluorescent protein (GFP) expression. Spectroscopic experiments measuring the two

  20. Quantitative phase imaging technologies to assess neuronal activity (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Thouvenin, Olivier; Fink, Mathias; Boccara, Claude

    2016-03-01

    Active neurons tends to have a different dynamical behavior compared to resting ones. Non-exhaustively, vesicular transport towards the synapses is increased, since axonal growth becomes slower. Previous studies also reported small phase variations occurring simultaneously with the action potential. Such changes exhibit times scales ranging from milliseconds to several seconds on spatial scales smaller than the optical diffraction limit. Therefore, QPI systems are of particular interest to measure neuronal activity without labels. Here, we report the development of two new QPI systems that should enable the detection of such activity. Both systems can acquire full field phase images with a sub nanometer sensitivity at a few hundreds of frames per second. The first setup is a synchronous combination of Full Field Optical Coherence Tomography (FF-OCT) and Fluorescence wide field imaging. The latter modality enables the measurement of neurons electrical activity using calcium indicators. In cultures, FF-OCT exhibits similar features to Digital Holographic Microscopy (DHM), except from complex computational reconstruction. However, FF-OCT is of particular interest in order to measure phase variations in tissues. The second setup is based on a Quantitative Differential Interference Contrast setup mounted in an epi-illumination configuration with a spectrally incoherent illumination. Such a common path interferometer exhibits a very good mechanical stability, and thus enables the measurement of phase images during hours. Additionally, such setup can not only measure a height change, but also an optical index change for both polarization. Hence, one can measure simultaneously a phase change and a birefringence change.

  1. Neuronal activity in rat barrel cortex underlying texture discrimination.

    PubMed

    von Heimendahl, Moritz; Itskov, Pavel M; Arabzadeh, Ehsan; Diamond, Mathew E

    2007-11-01

    Rats and mice palpate objects with their whiskers to generate tactile sensations. This form of active sensing endows the animals with the capacity for fast and accurate texture discrimination. The present work is aimed at understanding the nature of the underlying cortical signals. We recorded neuronal activity from barrel cortex while rats used their whiskers to discriminate between rough and smooth textures. On whisker contact with either texture, firing rate increased by a factor of two to ten. Average firing rate was significantly higher for rough than for smooth textures, and we therefore propose firing rate as the fundamental coding mechanism. The rat, however, cannot take an average across trials, but must make an immediate decision using the signals generated on each trial. To estimate single-trial signals, we calculated the mutual information between stimulus and firing rate in the time window leading to the rat's observed choice. Activity during the last 75 ms before choice transmitted the most informative signal; in this window, neuronal clusters carried, on average, 0.03 bits of information about the stimulus on trials in which the rat's behavioral response was correct. To understand how cortical activity guides behavior, we examined responses in incorrect trials and found that, in contrast to correct trials, neuronal firing rate was higher for smooth than for rough textures. Analysis of high-speed films suggested that the inappropriate signal on incorrect trials was due, at least in part, to nonoptimal whisker contact. In conclusion, these data suggest that barrel cortex firing rate on each trial leads directly to the animal's judgment of texture.

  2. Network of hypothalamic neurons that control appetite.

    PubMed

    Sohn, Jong-Woo

    2015-04-01

    The central nervous system (CNS) controls food intake and energy expenditure via tight coordinations between multiple neuronal populations. Specifically, two distinct neuronal populations exist in the arcuate nucleus of hypothalamus (ARH): the anorexigenic (appetite-suppressing) pro-opiomelanocortin (POMC) neurons and the orexigenic (appetite-increasing) neuropeptide Y (NPY)/agouti-related peptide (AgRP) neurons. The coordinated regulation of neuronal circuit involving these neurons is essential in properly maintaining energy balance, and any disturbance therein may result in hyperphagia/obesity or hypophagia/starvation. Thus, adequate knowledge of the POMC and NPY/AgRP neuron physiology is mandatory to understand the pathophysiology of obesity and related metabolic diseases. This review will discuss the history and recent updates on the POMC and NPY/AgRP neuronal circuits, as well as the general anorexigenic and orexigenic circuits in the CNS.

  3. Inhibition of propofol on single neuron and neuronal ensemble activity in prefrontal cortex of rats during working memory task.

    PubMed

    Xu, Xinyu; Tian, Yu; Wang, Guolin; Tian, Xin

    2014-08-15

    Working memory (WM) refers to the temporary storage and manipulation of information necessary for performance of complex cognitive tasks. There is a growing interest in whether and how propofol anesthesia inhibits WM function. The aim of this study is to investigate the possible inhibition mechanism of propofol anesthesia from the view of single neuron and neuronal ensemble activities. Adult SD rats were randomly divided into two groups: propofol group (0.9 mg kg(-1)min(-1), 2h via a tail vein catheter) and control group. All the rats were tested for working memory performances in a Y-maze-rewarded alternation task (a task of delayed non-matched-to-sample) at 24, 48, 72 h after propofol anesthesia, and the behavior results of WM tasks were recorded at the same time. Spatio-temporal trains of action potentials were obtained from the original signals. Single neuron activity was characterized by peri-event time histograms analysis and neuron ensemble activities were characterized by Granger causality to describe the interactions within the neuron ensemble. The results show that: comparing with the control group, the percentage of neurons excited and related to WM was significantly decreased (p<0.01 in 24h, p<0.05 in 48 h); the interactions within neuron ensemble were significantly weakened (p<0.01 in 24h, p<0.05 in 48 h), whereas no significant difference in 72 h (p>0.05), which were consistent with the behavior results. These findings could lead to improved understanding of the mechanism of anesthesia inhibition on WM functions from the view of single neuron activity and neuron ensemble interactions.

  4. Energetics of neuronal signaling and fMRI activity.

    PubMed

    Maandag, Natasja J G; Coman, Daniel; Sanganahalli, Basavaraju G; Herman, Peter; Smith, Arien J; Blumenfeld, Hal; Shulman, Robert G; Hyder, Fahmeed

    2007-12-18

    Energetics of resting and evoked fMRI signals were related to localized ensemble firing rates (nu) measured by electrophysiology in rats. Two different unstimulated, or baseline, states were established by anesthesia. Halothane and alpha-chloralose established baseline states of high and low energy, respectively, in which forepaw stimulation excited the contralateral primary somatosensory cortex (S1). With alpha-chloralose, forepaw stimulation induced strong and reproducible fMRI activations in the contralateral S1, where the ensemble firing was dominated by slow signaling neurons (SSN; nu range of 1-13 Hz). Under halothane, weaker and less reproducible fMRI activations were observed in the contralateral S1 and elsewhere in the cortex, but ensemble activity in S1 was dominated by rapid signaling neurons (RSN; nu range of 13-40 Hz). For both baseline states, the RSN activity (i.e., higher frequencies, including the gamma band) did not vary upon stimulation, whereas the SSN activity (i.e., alpha band and lower frequencies) did change. In the high energy baseline state, a large majority of total oxidative energy [cerebral metabolic rate of oxygen consumption (CMR(O2))] was devoted to RSN activity, whereas in the low energy baseline state, it was roughly divided between SSN and RSN activities. We hypothesize that in the high energy baseline state, the evoked changes in fMRI activation in areas beyond S1 are supported by rich intracortical interactions represented by RSN. We discuss implications for interpreting fMRI data where stimulus-specific DeltaCMR(O2) is generally small compared with baseline CMR(O2).

  5. Reconstruction of burst activity from calcium imaging of neuronal population via Lq minimization and interval screening

    PubMed Central

    Quan, Tingwei; Lv, Xiaohua; Liu, Xiuli; Zeng, Shaoqun

    2016-01-01

    Calcium imaging is becoming an increasingly popular technology to indirectly measure activity patterns in local neuronal networks. Based on the dependence of calcium fluorescence on neuronal spiking, two-photon calcium imaging affords single-cell resolution of neuronal population activity. However, it is still difficult to reconstruct neuronal activity from complex calcium fluorescence traces, particularly for traces contaminated by noise. Here, we describe a robust and efficient neuronal-activity reconstruction method that utilizes Lq minimization and interval screening (IS), which we refer to as LqIS. The simulation results show that LqIS performs satisfactorily in terms of both accuracy and speed of reconstruction. Reconstruction of simulation and experimental data also shows that LqIS has advantages in terms of the recall rate, precision rate, and timing error. Finally, LqIS is demonstrated to effectively reconstruct neuronal burst activity from calcium fluorescence traces recorded from large-size neuronal population. PMID:27375930

  6. Active transport of vesicles in neurons is modulated by mechanical tension

    NASA Astrophysics Data System (ADS)

    Ahmed, Wylie W.; Saif, Taher A.

    2014-03-01

    Effective intracellular transport of proteins and organelles is critical in cells, and is especially important for ensuring proper neuron functionality. In neurons, most proteins are synthesized in the cell body and must be transported through thin structures over long distances where normal diffusion is insufficient. Neurons transport subcellular cargo along axons and neurites through a stochastic interplay of active and passive transport. Mechanical tension is critical in maintaining proper function in neurons, but its role in transport is not well understood. To this end, we investigate the active and passive transport of vesicles in Aplysia neurons while changing neurite tension via applied strain, and quantify the resulting dynamics. We found that tension in neurons modulates active transport of vesicles by increasing the probability of active motion, effective diffusivity, and induces a retrograde bias. We show that mechanical tension modulates active transport processes in neurons and that external forces can couple to internal (subcellular) forces and change the overall transport dynamics.

  7. The Satiety Signaling Neuropeptide Perisulfakinin Inhibits the Activity of Central Neurons Promoting General Activity

    PubMed Central

    Wicher, Dieter; Derst, Christian; Gautier, Hélène; Lapied, Bruno; Heinemann, Stefan H.; Agricola, Hans-Jürgen

    2007-01-01

    The metabolic state is one of the determinants of the general activity level. Satiety is related to resting or sleep whereas hunger correlates to wakefulness and activity. The counterpart to the mammalian satiety signal cholecystokinin (CCK) in insects are the sulfakinins. The aim of this study was to resolve the mechanism by which the antifeedant activity of perisulfakinin (PSK) in Periplaneta americana is mediated. We identified the sources of PSK which is used both as hormone and as paracrine messenger. PSK is found in the neurohemal organ of the brain and in nerve endings throughout the central nervous system. To correlate the distributions of PSK and its receptor (PSKR), we cloned the gene coding for PSKR and provide evidence for its expression within the nervous system. It occurs only in a few neurons, among them are the dorsal unpaired median (DUM) neurons which release octopamine thereby regulating the general level of activity. Application of PSK to DUM neurons attenuated the spiking frequency (EC50=11pM) due to reduction of a pacemaker Ca2+ current through cAMP-inhibited pTRPγ channels. PSK increased the intracellular cAMP level while decreasing the intracellular Ca2+ concentration in DUM neurons. Thus, the satiety signal conferred by PSK acts antagonistically to the hunger signal, provided by the adipokinetic hormone (AKH): PSK depresses the electrical activity of DUM neurons by inhibiting the pTRPγ channel that is activated by AKH under conditions of food shortage. PMID:18946521

  8. Satellite microglia show spontaneous electrical activity that is uncorrelated with activity of the attached neuron.

    PubMed

    Wogram, Emile; Wendt, Stefan; Matyash, Marina; Pivneva, Tatyana; Draguhn, Andreas; Kettenmann, Helmut

    2016-06-01

    Microglia are innate immune cells of the brain. We have studied a subpopulation of microglia, called satellite microglia. This cell type is defined by a close morphological soma-to-soma association with a neuron, indicative of a direct functional interaction. Indeed, ultrastructural analysis revealed closely attached plasma membranes of satellite microglia and neurons. However, we found no apparent morphological specializations of the contact, and biocytin injection into satellite microglia showed no dye-coupling with the apposed neurons or any other cell. Likewise, evoked local field potentials or action potentials and postsynaptic potentials of the associated neuron did not lead to any transmembrane currents or non-capacitive changes in the membrane potential of the satellite microglia in the cortex and hippocampus. Both satellite and non-satellite microglia, however, showed spontaneous transient membrane depolarizations that were not correlated with neuronal activity. These events could be divided into fast-rising and slow-rising depolarizations, which showed different characteristics in satellite and non-satellite microglia. Fast-rising and slow-rising potentials differed with regard to voltage dependence. The frequency of these events was not affected by the application of tetrodotoxin, but the fast-rising event frequency decreased after application of GABA. We conclude that microglia show spontaneous electrical activity that is uncorrelated with the activity of adjacent neurons.

  9. Activity-dependent modulation of gonadotrophin-releasing hormone neurone activity by acute oestradiol.

    PubMed

    Romanò, Nicola; Herbison, Allan E

    2012-10-01

    Oestradiol (E₂) exerts potent feedback actions upon gonadotrophin-releasing hormone (GnRH) neurones and part of this feedback action may occur through the rapid action of E₂. Using a transgenic GnRH-Pericam mouse line that allows real-time intracellular calcium concentrations ([Ca²⁺](i)) to be monitored in adult GnRH neurones in a brain slice preparation, we examined the acute effects of 100 pM-100 nM E₂ on [Ca²⁺](i) transients in spontaneously active GnRH neurones. Approximately 30% of GnRH neurones exhibit spontaneous [Ca²⁺](i) transients at a frequency greater than two transients/15 min in adult female mice. In these cells, treatment with an incremental 1, 10, 100 nM E₂ protocol or 100 pM E₂ alone resulted in the suppression or complete cessation of [Ca²⁺](i) transients in 15 of 18 (83%) GnRH neurones. This effect was mimicked by E₂ bound to albumin, suggesting a membrane site of action, and was maintained in oestrogen receptor β knockout mice, indicating that this receptor is not essential for the rapid suppression of [Ca²⁺](i) transients. These findings contrast with those GnRH neurones exhibiting very few or no [Ca²⁺](i) transients (< 2 transients/15 min) that exhibit the opposite response of being activated by acute E₂. A series of dual calcium-cell-attached electrical recordings showed that [Ca²⁺](i) transients were associated with GnRH neurone burst firing and that E₂ suppression or activation of [Ca²⁺](i) transients was mirrored by a depression or initiation of burst firing. Taken together, these studies demonstrate that the acute actions of E₂ on GnRH neurones are critically dependent upon their pattern of burst firing.

  10. Nicotine Elicits Convulsive Seizures by Activating Amygdalar Neurons

    PubMed Central

    Iha, Higor A.; Kunisawa, Naofumi; Shimizu, Saki; Tokudome, Kentaro; Mukai, Takahiro; Kinboshi, Masato; Ikeda, Akio; Ito, Hidefumi; Serikawa, Tadao; Ohno, Yukihiro

    2017-01-01

    Nicotinic acetylcholine (nACh) receptors are implicated in the pathogenesis of epileptic disorders; however, the mechanisms of nACh receptors in seizure generation remain unknown. Here, we performed behavioral and immunohistochemical studies in mice and rats to clarify the mechanisms underlying nicotine-induced seizures. Treatment of animals with nicotine (1–4 mg/kg, i.p.) produced motor excitement in a dose-dependent manner and elicited convulsive seizures at 3 and 4 mg/kg. The nicotine-induced seizures were abolished by a subtype non-selective nACh antagonist, mecamylamine (MEC). An α7 nACh antagonist, methyllycaconitine, also significantly inhibited nicotine-induced seizures whereas an α4β2 nACh antagonist, dihydro-β-erythroidine, affected only weakly. Topographical analysis of Fos protein expression, a biological marker of neural excitation, revealed that a convulsive dose (4 mg/kg) of nicotine region-specifically activated neurons in the piriform cortex, amygdala, medial habenula, paratenial thalamus, anterior hypothalamus and solitary nucleus among 48 brain regions examined, and this was also suppressed by MEC. In addition, electric lesioning of the amygdala, but not the piriform cortex, medial habenula and thalamus, specifically inhibited nicotine-induced seizures. Furthermore, microinjection of nicotine (100 and 300 μg/side) into the amygdala elicited convulsive seizures in a dose-related manner. The present results suggest that nicotine elicits convulsive seizures by activating amygdalar neurons mainly via α7 nACh receptors. PMID:28232801

  11. Caffeine enhances micturition through neuronal activation in micturition centers.

    PubMed

    Cho, Young-Sam; Ko, Il-Gyu; Kim, Sung-Eun; Hwan, Lakkyong; Shin, Mal-Soon; Kim, Chang-Ju; Kim, Sang-Hoon; Jin, Jun-Jang; Chung, Jun-Young; Kim, Khae-Hawn

    2014-12-01

    Caffeine may promote incontinence through its diuretic effect, particularly in individuals with underlying detrusor overactivity, in addition to increasing muscle contraction of the bladder smooth muscle. Caffeine may also affect bladder function via central micturition centers, including the medial preoptic area, ventrolateral periaqueductal gray, and pontine micturition center. However, the biochemical mechanisms of caffeine in central micturition centers affecting bladder function remain unclear. In the present study, the effects of caffeine on the central micturition reflex were investigated by measuring the degree of neuronal activation, and by quantifying nerve growth factor (NGF) expression in rats. Following caffeine administration for 14 days, a urodynamic study was performed to assess the changes to bladder function. Subsequently, immunohistochemical staining to identify the expression of c‑Fos and NGF in the central micturition areas was performed. Ingestion of caffeine increased bladder smooth muscle contraction pressure and time as determined by cystometry. Expression levels of c‑Fos and NGF in all central micturition areas were significantly increased following the administration of caffeine. The effects on contraction pressure and time were the most potent and expression levels of c‑Fos and NGF were greatest at the lowest dose of caffeine. These results suggest that caffeine facilitates bladder instability through enhancing neuronal activation in the central micturition areas.

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

    PubMed Central

    Hutt, Axel; Mierau, Andreas; Lefebvre, Jérémie

    2016-01-01

    Oscillatory brain activity is believed to play a central role in neural coding. Accumulating evidence shows that features of these oscillations are highly dynamic: power, frequency and phase fluctuate alongside changes in behavior and task demands. The role and mechanism supporting this variability is however poorly understood. We here analyze a network of recurrently connected spiking neurons with time delay displaying stable synchronous dynamics. Using mean-field and stability analyses, we investigate the influence of dynamic inputs on the frequency of firing rate oscillations. We show that afferent noise, mimicking inputs to the neurons, causes smoothing of the system’s response function, displacing equilibria and altering the stability of oscillatory states. Our analysis further shows that these noise-induced changes cause a shift of the peak frequency of synchronous oscillations that scales with input intensity, leading the network towards critical states. We lastly discuss the extension of these principles to periodic stimulation, in which externally applied driving signals can trigger analogous phenomena. Our results reveal one possible mechanism involved in shaping oscillatory activity in the brain and associated control principles. PMID:27669018

  13. KIF4 motor regulates activity-dependent neuronal survival by suppressing PARP-1 enzymatic activity.

    PubMed

    Midorikawa, Ryosuke; Takei, Yosuke; Hirokawa, Nobutaka

    2006-04-21

    In brain development, apoptosis is a physiological process that controls the final numbers of neurons. Here, we report that the activity-dependent prevention of apoptosis in juvenile neurons is regulated by kinesin superfamily protein 4 (KIF4), a microtubule-based molecular motor. The C-terminal domain of KIF4 is a module that suppresses the activity of poly (ADP-ribose) polymerase-1 (PARP-1), a nuclear enzyme known to maintain cell homeostasis by repairing DNA and serving as a transcriptional regulator. When neurons are stimulated by membrane depolarization, calcium signaling mediated by CaMKII induces dissociation of KIF4 from PARP-1, resulting in upregulation of PARP-1 activity, which supports neuron survival. After dissociation from PARP-1, KIF4 enters into the cytoplasm from the nucleus and moves to the distal part of neurites in a microtubule-dependent manner. We suggested that KIF4 controls the activity-dependent survival of postmitotic neurons by regulating PARP-1 activity in brain development.

  14. Active cortical innervation protects striatal neurons from slow degeneration in culture.

    PubMed

    Fishbein, Ianai; Segal, Menahem

    2011-03-01

    Spiny striatal GABAergic neurons receive most of their excitatory input from the neocortex. In culture, striatal neurons form inhibitory connections, but the lack of intrinsic excitatory afferents prevents the development of spontaneous network activity. Addition of cortical neurons to the striatal culture provides the necessary excitatory input to the striatal neurons, and in the presence of these neurons, striatal cultures do express spontaneous network activity. We have confirmed that cortical neurons provide excitatory drive to striatal neurons in culture using paired recording from cortical and striatal neurons. In the presence of tetrodotoxin (TTX), which blocks action potential discharges, the connections between cortical and striatal neurons are still formed, and in fact synaptic currents generated between them when TTX is removed are far larger than in control, undrugged cultures. Interestingly, the continuous presence of TTX in the co-culture caused striatal cell death. These observations indicate that the mere presence of cortical neurons is not sufficient to preserve striatal neurons in culture, but their synchronous activity, triggered by cortical excitatory synapses, is critical for the maintenance of viability of striatal neurons. These results have important implications for understanding the role of activity in neurodegenerative diseases of the striatum.

  15. Chemical Genetics: receptor-ligand pairs for rapid manipulation of neuronal activity

    PubMed Central

    Wulff, Peer; Arenkiel, Benjamin R.

    2012-01-01

    Towards the functional dissection of neuronal circuits, a number of new genetic tools have been developed that enable rapid and reversible manipulation of genetically defined neuronal subtypes in intact mammalian brain circuits. Alongside the breakthrough technology of optogenetics, receptor-ligand pairs provide complementary approaches to modulate neuronal activity using chemical-genetics. PMID:22119143

  16. Assessing the sensitivity of diffusion MRI to detect neuronal activity directly

    PubMed Central

    Bai, Ruiliang; Stewart, Craig V.; Plenz, Dietmar; Basser, Peter J.

    2016-01-01

    Functional MRI (fMRI) is widely used to study brain function in the neurosciences. Unfortunately, conventional fMRI only indirectly assesses neuronal activity via hemodynamic coupling. Diffusion fMRI was proposed as a more direct and accurate fMRI method to detect neuronal activity, yet confirmative findings have proven difficult to obtain. Given that the underlying relation between tissue water diffusion changes and neuronal activity remains unclear, the rationale for using diffusion MRI to monitor neuronal activity has yet to be clearly established. Here, we studied the correlation between water diffusion and neuronal activity in vitro by simultaneous calcium fluorescence imaging and diffusion MR acquisition. We used organotypic cortical cultures from rat brains as a biological model system, in which spontaneous neuronal activity robustly emerges free of hemodynamic and other artifacts. Simultaneous fluorescent calcium images of neuronal activity are then directly correlated with diffusion MR signals now free of confounds typically encountered in vivo. Although a simultaneous increase of diffusion-weighted MR signals was observed together with the prolonged depolarization of neurons induced by pharmacological manipulations (in which cell swelling was demonstrated to play an important role), no evidence was found that diffusion MR signals directly correlate with normal spontaneous neuronal activity. These results suggest that, whereas current diffusion MR methods could monitor pathological conditions such as hyperexcitability, e.g., those seen in epilepsy, they do not appear to be sensitive or specific enough to detect or follow normal neuronal activity. PMID:26941239

  17. Assessing the sensitivity of diffusion MRI to detect neuronal activity directly.

    PubMed

    Bai, Ruiliang; Stewart, Craig V; Plenz, Dietmar; Basser, Peter J

    2016-03-22

    Functional MRI (fMRI) is widely used to study brain function in the neurosciences. Unfortunately, conventional fMRI only indirectly assesses neuronal activity via hemodynamic coupling. Diffusion fMRI was proposed as a more direct and accurate fMRI method to detect neuronal activity, yet confirmative findings have proven difficult to obtain. Given that the underlying relation between tissue water diffusion changes and neuronal activity remains unclear, the rationale for using diffusion MRI to monitor neuronal activity has yet to be clearly established. Here, we studied the correlation between water diffusion and neuronal activity in vitro by simultaneous calcium fluorescence imaging and diffusion MR acquisition. We used organotypic cortical cultures from rat brains as a biological model system, in which spontaneous neuronal activity robustly emerges free of hemodynamic and other artifacts. Simultaneous fluorescent calcium images of neuronal activity are then directly correlated with diffusion MR signals now free of confounds typically encountered in vivo. Although a simultaneous increase of diffusion-weighted MR signals was observed together with the prolonged depolarization of neurons induced by pharmacological manipulations (in which cell swelling was demonstrated to play an important role), no evidence was found that diffusion MR signals directly correlate with normal spontaneous neuronal activity. These results suggest that, whereas current diffusion MR methods could monitor pathological conditions such as hyperexcitability, e.g., those seen in epilepsy, they do not appear to be sensitive or specific enough to detect or follow normal neuronal activity.

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

    PubMed

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

    2011-12-01

    GABA projection neurons (GABA neurons) in the substantia nigra pars reticulata (SNr) and dopamine projection neurons (DA neurons) in substantia nigra pars compacta (SNc) have strikingly different firing properties. SNc DA neurons fire low-frequency, long-duration spikes, whereas SNr GABA neurons fire high-frequency, short-duration spikes. Since voltage-activated sodium (Na(V)) channels are critical to spike generation, the different firing properties raise the possibility that, compared with DA neurons, Na(V) channels in SNr GABA neurons have higher density, faster kinetics, and less cumulative inactivation. Our quantitative RT-PCR analysis on immunohistochemically identified nigral neurons indicated that mRNAs for pore-forming Na(V)1.1 and Na(V)1.6 subunits and regulatory Na(V)β1 and Na(v)β4 subunits are more abundant in SNr GABA neurons than SNc DA neurons. These α-subunits and β-subunits are key subunits for forming Na(V) channels conducting the transient Na(V) current (I(NaT)), persistent Na current (I(NaP)), and resurgent Na current (I(NaR)). Nucleated patch-clamp recordings showed that I(NaT) had a higher density, a steeper voltage-dependent activation, and a faster deactivation in SNr GABA neurons than in SNc DA neurons. I(NaT) also recovered more quickly from inactivation and had less cumulative inactivation in SNr GABA neurons than in SNc DA neurons. Furthermore, compared with nigral DA neurons, SNr GABA neurons had a larger I(NaR) and I(NaP). Blockade of I(NaP) induced a larger hyperpolarization in SNr GABA neurons than in SNc DA neurons. Taken together, these results indicate that Na(V) channels expressed in fast-spiking SNr GABA neurons and slow-spiking SNc DA neurons are tailored to support their different spiking capabilities.

  19. Activation of perineuronal net-expressing excitatory neurons during associative memory encoding and retrieval

    PubMed Central

    Morikawa, Shota; Ikegaya, Yuji; Narita, Minoru; Tamura, Hideki

    2017-01-01

    Perineuronal nets (PNNs), proteoglycan-rich extracellular matrix structures, are thought to be expressed around inhibitory neurons and contribute to critical periods of brain function and synaptic plasticity. However, in some specific brain regions such as the amygdala, PNNs were predominantly expressed around excitatory neurons. These neurons were recruited during auditory fear conditioning and memory retrieval. Indeed, the activation of PNN-expressing excitatory neurons predicted cognitive performance. PMID:28378772

  20. Multi-neuronal activity and functional connectivity in cell assemblies.

    PubMed

    Roudi, Yasser; Dunn, Benjamin; Hertz, John

    2015-06-01

    Our ability to collect large amounts of data from many cells has been paralleled by the development of powerful statistical models for extracting information from this data. Here we discuss how the activity of cell assemblies can be analyzed using these models, focusing on the generalized linear models and the maximum entropy models and describing a number of recent studies that employ these tools for analyzing multi-neuronal activity. We show results from simulations comparing inferred functional connectivity, pairwise correlations and the real synaptic connections in simulated networks demonstrating the power of statistical models in inferring functional connectivity. Further development of network reconstruction techniques based on statistical models should lead to more powerful methods of understanding functional anatomy of cell assemblies.

  1. Interneuron-mediated inhibition synchronizes neuronal activity during slow oscillation

    PubMed Central

    Chen, Jen-Yung; Chauvette, Sylvain; Skorheim, Steven; Timofeev, Igor; Bazhenov, Maxim

    2012-01-01

    The signature of slow-wave sleep in the electroencephalogram (EEG) is large-amplitude fluctuation of the field potential, which reflects synchronous alternation of activity and silence across cortical neurons. While initiation of the active cortical states during sleep slow oscillation has been intensively studied, the biological mechanisms which drive the network transition from an active state to silence remain poorly understood. In the current study, using a combination of in vivo electrophysiology and thalamocortical network simulation, we explored the impact of intrinsic and synaptic inhibition on state transition during sleep slow oscillation. We found that in normal physiological conditions, synaptic inhibition controls the duration and the synchrony of active state termination. The decline of interneuron-mediated inhibition led to asynchronous downward transition across the cortical network and broke the regular slow oscillation pattern. Furthermore, in both in vivo experiment and computational modelling, we revealed that when the level of synaptic inhibition was reduced significantly, it led to a recovery of synchronized oscillations in the form of seizure-like bursting activity. In this condition, the fast active state termination was mediated by intrinsic hyperpolarizing conductances. Our study highlights the significance of both intrinsic and synaptic inhibition in manipulating sleep slow rhythms. PMID:22641778

  2. Physiological Brain Activity Causes DNA Double Strand Breaks in Neurons — Exacerbation by Amyloid-β

    PubMed Central

    Suberbielle, Elsa; Sanchez, Pascal E.; Kravitz, Alexxai V.; Wang, Xin; Ho, Kaitlyn; Eilertson, Kirsten; Devidze, Nino; Kreitzer, Anatol C.; Mucke, Lennart

    2013-01-01

    We show that a natural behavior, exploration of a novel environment, causes DNA double-strand breaks (DSBs) in neurons of young adult wildtype mice. DSBs occurred in multiple brain regions, were most abundant in the dentate gyrus, which is involved in spatial learning and memory, and were repaired within 24 hours. Increasing neuronal activity by sensory or optogenetic stimulation increased neuronal DSBs in relevant but not irrelevant networks. Human amyloid precursor protein (hAPP) transgenic mice, which simulate key aspects of Alzheimer's disease, had increased neuronal DSBs at baseline and more severe and prolonged DSBs after exploration. Interventions that suppress aberrant neuronal activity and improve memory in hAPP mice normalized their levels of DSBs. Blocking extrasynaptic NMDA-type glutamate receptors prevented amyloid-β (Aβ)-induced DSBs in neuronal cultures. Thus, transient increases in neuronal DSBs occur as a result of physiological brain activity and Aβ exacerbates DNA damage, most likely by eliciting synaptic dysfunction. PMID:23525040

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

    PubMed

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

    2016-06-23

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

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

    PubMed Central

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

    2016-01-01

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

  5. Treadmill exercise prevents GABAergic neuronal loss with suppression of neuronal activation in the pilocarpine-induced epileptic rats

    PubMed Central

    Lim, Baek-Vin; Shin, Mal-Soon; Lee, Jae-Min; Seo, Jin-Hee

    2015-01-01

    Epilepsy is a common neurological disorder characterized by seizure and loss of neuronal cells by abnormal rhythmic firing of neurons in the brain. In the present study, we investigated the effect of treadmill exercise on gamma-aminobutyric acid (GABA)ergic neuronal loss in relation with neuronal activation using pilocarpine-induced epileptic rats. The rats were divided into four groups: control group, control and treadmill exercise group, pilocarpine-induced epilepsy group, and pilocarpine-induced epilepsy and treadmill exercise group. Epilepsy was induced by intraperitoneal injection of 320 mg/kg pilocarpine hydrochloride. The rats in the exercise groups were forced to run on a motorized treadmill for 30 min once a day for 2 weeks. In the present results, neuronal loss in the hippocampal CA1 region was increased after pilocarpine-induced seizure. Treadmill exercise inhibited hippocampal neuronal loss in the epileptic rats. Glutamic acid decarboxylase (GAD67) expression in the hippocampal CA1 region was reduced by pilocarpine-induced seizure. Treadmill exercise increased GAD67 expression in the epileptic rats. c-Fos expression in the hippocampal CA1 region was increased in response to epileptic seizure. Treadmill exercise inhibited c-Fos expression in the epileptic rats. Epileptic seizure increased brain-derived neurotrophic factor (BDNF) and tyrosine kinase receptor B (TrkB) expressions in the hippocampus. Treadmill exercise suppressed BDNF and TrkB expressions in the epileptic rats. In the present study, treadmill exercise prevented GABAergic neuronal loss and inhibited neuronal activation in the hippocampal CA1 region through the down-regulation of BDNF-TrkB signaling pathway. PMID:25960980

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

    PubMed

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

    2014-01-01

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

  7. Guinea Pig Kisspeptin Neurons Are Depolarized by Leptin via Activation of TRPC Channels

    PubMed Central

    Qiu, Jian; Fang, Yuan; Bosch, Martha A.

    2011-01-01

    Hypothalamic kisspeptin neurons are critical for driving reproductive function, but virtually nothing is known about their endogenous electrophysiological properties and the effects of leptin on their excitability. Therefore, we used the slice preparation from female guinea pigs to study the endogenous conductances and the effects of leptin on kisspeptin neurons. We targeted the arcuate kisspeptin neurons using visualized-patch whole-cell recording and identified kisspeptin neurons using immuocytochemical staining for kisspeptin or single cell RT-PCR. We also harvested dispersed arcuate neurons for analysis of expression of channel transcripts. Kisspeptin neurons exhibited a relatively negative resting membrane potential, and eighty percent of the neurons expressed a pacemaker current (h-current) and a T-type Ca2+ current. Furthermore, the glutamate receptor agonist N-methyl D-aspartic acid depolarized and induced burst firing in kisspeptin neurons. Leptin activated an inward current that depolarized kisspeptin neurons and increased (burst) firing, but leptin hyperpolarized NPY neurons. Lanthanum, a TRPC-4,-5 channel activator, potentiated the leptin-induced inward current by 170%. The leptin-activated current reversed near −15 mV and was abrogated by the relatively selective TRPC channel blocker 2-APB. The leptin effects were also blocked by a Janus kinase inhibitor, a phosphatidylinositol 3 kinase inhibitor, and a phospholipase Cγ inhibitor. In addition, the majority of these neurons expressed TRPC1 and -5 and phospholipase Cγ1 based on single cell RT-PCR. Therefore, guinea pig kisspeptin neurons express endogenous pacemaker currents, and leptin excites these neurons via activation of TRPC channels. The leptin excitatory effects on kisspeptin neurons may be critical for governing the excitatory drive to GnRH neurons during different nutritional states. PMID:21285322

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

    PubMed

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

    2013-06-05

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

  9. Sudden synchrony leaps accompanied by frequency multiplications in neuronal activity

    PubMed Central

    Vardi, Roni; Goldental, Amir; Guberman, Shoshana; Kalmanovich, Alexander; Marmari, Hagar; Kanter, Ido

    2013-01-01

    A classical view of neural coding relies on temporal firing synchrony among functional groups of neurons, however, the underlying mechanism remains an enigma. Here we experimentally demonstrate a mechanism where time-lags among neuronal spiking leap from several tens of milliseconds to nearly zero-lag synchrony. It also allows sudden leaps out of synchrony, hence forming short epochs of synchrony. Our results are based on an experimental procedure where conditioned stimulations were enforced on circuits of neurons embedded within a large-scale network of cortical cells in vitro and are corroborated by simulations of neuronal populations. The underlying biological mechanisms are the unavoidable increase of the neuronal response latency to ongoing stimulations and temporal or spatial summation required to generate evoked spikes. These sudden leaps in and out of synchrony may be accompanied by multiplications of the neuronal firing frequency, hence offering reliable information-bearing indicators which may bridge between the two principal neuronal coding paradigms. PMID:24198764

  10. Activation of TRPV4 Regulates Respiration through Indirect Activation of Bronchopulmonary Sensory Neurons

    PubMed Central

    Gu, Qihai (David); Moss, Charles R.; Kettelhut, Kristen L.; Gilbert, Carolyn A.; Hu, Hongzhen

    2016-01-01

    Transient receptor potential vanilloid receptor 4 (TRPV4) is a calcium-permeable non-selective cation channel implicated in numerous physiological and pathological functions. This study aimed to investigate the effect of TRPV4 activation on respiration and to explore the potential involvement of bronchopulmonary sensory neurons. Potent TRPV4 agonist GSK1016790A was injected into right atrium in anesthetized spontaneously breathing rats and the changes in breathing were measured. Patch-clamp recording was performed to investigate the effect of GSK1016790A or another TRPV4 activator 4α-PDD on cultured rat vagal bronchopulmonary sensory neurons. Immunohistochemistry was carried out to determine the TRPV4-expressing cells in lung slices obtained from TRPV4-EGFP mice. Our results showed, that right-atrial injection of GSK1016790A evoked a slow-developing, long-lasting rapid shallow breathing in anesthetized rats. Activation of TRPV4 also significantly potentiated capsaicin-evoked chemoreflex responses. The alteration in ventilation induced by GSK1016790A was abolished by cutting or perineural capsaicin treatment of both vagi, indicating the involvement of bronchopulmonary afferent neurons. The stimulating and sensitizing effects of GSK1016790A were abolished by a selective TRPV4 antagonist GSK2193874 and also by inhibiting cyclooxygenase with indomethacin. Surprising, GSK1016790A or 4α-PDD did not activate isolated bronchopulmonary sensory neurons, nor did they modulate capsaicin-induced inward currents in these neurons. Furthermore, TRPV4 expression was found in alveolar macrophages, alveolar epithelial, and vascular endothelial cells. Collectively, our results suggest that GSK1016790A regulates the respiration through an indirect activation of bronchopulmonary sensory neurons, likely via its stimulation of other TRPV4-expressing cells in the lungs and airways. PMID:26973533

  11. Calcium imaging of sleep-wake related neuronal activity in the dorsal pons.

    PubMed

    Cox, Julia; Pinto, Lucas; Dan, Yang

    2016-02-25

    The dorsal pons has long been implicated in the generation of rapid eye movement (REM) sleep, but the underlying circuit mechanisms remain poorly understood. Using cell-type-specific microendoscopic Ca(2+) imaging in and near the laterodorsal tegmental nucleus, we found that many glutamatergic neurons are maximally active during REM sleep (REM-max), while the majority of GABAergic neurons are maximally active during wakefulness (wake-max). Furthermore, the activity of glutamatergic neurons exhibits a medio-lateral spatial gradient, with medially located neurons more selectively active during REM sleep.

  12. Domoic acid disrupts the activity and connectivity of neuronal networks in organotypic brain slice cultures.

    PubMed

    Hiolski, E M; Ito, S; Beggs, J M; Lefebvre, K A; Litke, A M; Smith, D R

    2016-09-01

    Domoic acid is a neurotoxin produced by algae and is found in seafood during harmful algal blooms. As a glutamate agonist, domoic acid inappropriately stimulates excitatory activity in neurons. At high doses, this leads to seizures and brain lesions, but it is unclear how lower, asymptomatic exposures disrupt neuronal activity. Domoic acid has been detected in an increasing variety of species across a greater geographical range than ever before, making it critical to understand the potential health impacts of low-level exposure on vulnerable marine mammal and human populations. To determine whether prolonged domoic acid exposure altered neuronal activity in hippocampal networks, we used a custom-made 512 multi-electrode array with high spatial and temporal resolution to record extracellular potentials (spikes) in mouse organotypic brain slice cultures. We identified individual neurons based on spike waveform and location, and measured the activity and functional connectivity within the neuronal networks of brain slice cultures. Domoic acid exposure significantly altered neuronal spiking activity patterns, and increased functional connectivity within exposed cultures, in the absence of overt cellular or neuronal toxicity. While the overall spiking activity of neurons in domoic acid-exposed cultures was comparable to controls, exposed neurons spiked significantly more often in bursts. We also identified a subset of neurons that were electrophysiologically silenced in exposed cultures, and putatively identified those neurons as fast-spiking inhibitory neurons. These results provide evidence that domoic acid affects neuronal activity in the absence of cytotoxicity, and suggest that neurodevelopmental exposure to domoic acid may alter neurological function in the absence of clinical symptoms.

  13. Tremor-correlated neuronal activity in the subthalamic nucleus of Parkinsonian patients.

    PubMed

    Amtage, Florian; Henschel, Kathrin; Schelter, Björn; Vesper, Jan; Timmer, Jens; Lücking, Carl Hermann; Hellwig, Bernhard

    2008-09-19

    Tremor in Parkinson's disease (PD) is generated by an oscillatory neuronal network consisting of cortex, basal ganglia and thalamus. The subthalamic nucleus (STN) which is part of the basal ganglia is of particular interest, since deep brain stimulation of the STN is an effective treatment for PD including Parkinsonian tremor. It is controversial if and how the STN contributes to tremor generation. In this study, we analyze neuronal STN activity in seven patients with Parkinsonian rest tremor who underwent stereotactic surgery for deep brain stimulation. Surface EMG was recorded from the wrist flexors and extensors. Simultaneously, neuronal spike activity was registered in different depths of the STN using an array of five microelectrodes. After spike-sorting, spectral coherence was analyzed between spike activity of STN neurons and tremor activity. Significant coherence at the tremor frequency was detected between EMG and neuronal STN activity in 76 out of 145 neurons (52.4%). In contrast, coherence in the beta band occurred only in 10 out of 145 neurons (6.9%). Tremor-coherent STN activity was widely distributed over the STN being more frequent in its dorsal parts (70.8-88.9%) than in its ventral parts (25.0-48.0%). Our results suggest that synchronous neuronal STN activity at the tremor frequency contributes to the pathogenesis of Parkinsonian tremor. The wide-spread spatial distribution of tremor-coherent spike activity argues for the recruitment of an extended network of subthalamic neurons for tremor generation.

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

    PubMed

    Spencer, Robert M; Blitz, Dawn M

    2016-06-01

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

  15. Tiagabine Protects Dopaminergic Neurons against Neurotoxins by Inhibiting Microglial Activation

    PubMed Central

    Liu, Jie; Huang, Dongping; Xu, Jing; Tong, Jiabin; Wang, Zishan; Huang, Li; Yang, Yufang; Bai, Xiaochen; Wang, Pan; Suo, Haiyun; Ma, Yuanyuan; Yu, Mei; Fei, Jian; Huang, Fang

    2015-01-01

    Microglial activation and inflammation are associated with progressive neuronal apoptosis in neurodegenerative disorders such as Parkinson’s disease (PD). γ-Aminobutyric acid (GABA), the major inhibitory neurotransmitter in the central nervous system, has recently been shown to play an inhibitory role in the immune system. Tiagabine, a piperidine derivative, enhances GABAergic transmission by inhibiting GABA transporter 1 (GAT 1). In the present study, we found that tiagabine pretreatment attenuated microglial activation, provided partial protection to the nigrostriatal axis and improved motor deficits in a methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD. The protective function of tiagabine was abolished in GAT 1 knockout mice that were challenged with MPTP. In an alternative PD model, induced by intranigral infusion of lipopolysaccharide (LPS), microglial suppression and subsequent neuroprotective effects of tiagabine were demonstrated. Furthermore, the LPS-induced inflammatory activation of BV-2 microglial cells and the toxicity of conditioned medium toward SH-SY5Y cells were inhibited by pretreatment with GABAergic drugs. The attenuation of the nuclear translocation of nuclear factor κB (NF-κB) and the inhibition of the generation of inflammatory mediators were the underlying mechanisms. Our results suggest that tiagabine acts as a brake for nigrostriatal microglial activation and that it might be a novel therapeutic approach for PD. PMID:26499517

  16. Tiagabine Protects Dopaminergic Neurons against Neurotoxins by Inhibiting Microglial Activation.

    PubMed

    Liu, Jie; Huang, Dongping; Xu, Jing; Tong, Jiabin; Wang, Zishan; Huang, Li; Yang, Yufang; Bai, Xiaochen; Wang, Pan; Suo, Haiyun; Ma, Yuanyuan; Yu, Mei; Fei, Jian; Huang, Fang

    2015-10-26

    Microglial activation and inflammation are associated with progressive neuronal apoptosis in neurodegenerative disorders such as Parkinson's disease (PD). γ-Aminobutyric acid (GABA), the major inhibitory neurotransmitter in the central nervous system, has recently been shown to play an inhibitory role in the immune system. Tiagabine, a piperidine derivative, enhances GABAergic transmission by inhibiting GABA transporter 1 (GAT 1). In the present study, we found that tiagabine pretreatment attenuated microglial activation, provided partial protection to the nigrostriatal axis and improved motor deficits in a methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD. The protective function of tiagabine was abolished in GAT 1 knockout mice that were challenged with MPTP. In an alternative PD model, induced by intranigral infusion of lipopolysaccharide (LPS), microglial suppression and subsequent neuroprotective effects of tiagabine were demonstrated. Furthermore, the LPS-induced inflammatory activation of BV-2 microglial cells and the toxicity of conditioned medium toward SH-SY5Y cells were inhibited by pretreatment with GABAergic drugs. The attenuation of the nuclear translocation of nuclear factor κB (NF-κB) and the inhibition of the generation of inflammatory mediators were the underlying mechanisms. Our results suggest that tiagabine acts as a brake for nigrostriatal microglial activation and that it might be a novel therapeutic approach for PD.

  17. Neuroligin-1 links neuronal activity to sleep-wake regulation

    PubMed Central

    El Helou, Janine; Bélanger-Nelson, Erika; Freyburger, Marlène; Dorsaz, Stéphane; Curie, Thomas; La Spada, Francesco; Gaudreault, Pierre-Olivier; Beaumont, Éric; Pouliot, Philippe; Lesage, Frédéric; Frank, Marcos G.; Franken, Paul; Mongrain, Valérie

    2013-01-01

    Maintaining wakefulness is associated with a progressive increase in the need for sleep. This phenomenon has been linked to changes in synaptic function. The synaptic adhesion molecule Neuroligin-1 (NLG1) controls the activity and synaptic localization of N-methyl-d-aspartate receptors, which activity is impaired by prolonged wakefulness. We here highlight that this pathway may underlie both the adverse effects of sleep loss on cognition and the subsequent changes in cortical synchrony. We found that the expression of specific Nlg1 transcript variants is changed by sleep deprivation in three mouse strains. These observations were associated with strain-specific changes in synaptic NLG1 protein content. Importantly, we showed that Nlg1 knockout mice are not able to sustain wakefulness and spend more time in nonrapid eye movement sleep than wild-type mice. These changes occurred with modifications in waking quality as exemplified by low theta/alpha activity during wakefulness and poor preference for social novelty, as well as altered delta synchrony during sleep. Finally, we identified a transcriptional pathway that could underlie the sleep/wake-dependent changes in Nlg1 expression and that involves clock transcription factors. We thus suggest that NLG1 is an element that contributes to the coupling of neuronal activity to sleep/wake regulation. PMID:23716671

  18. Design, pharmacology, and NMR structure of a minimized cystine knot with agouti-related protein activity.

    PubMed

    Jackson, Pilgrim J; McNulty, Joseph C; Yang, Ying-Kui; Thompson, Darren A; Chai, Biaoxin; Gantz, Ira; Barsh, Gregory S; Millhauser, Glenn L

    2002-06-18

    The agouti-related protein (AGRP) is an endogenous antagonist of the melanocortin receptors MC3R and MC4R found in the hypothalamus and exhibits potent orexigenic activity. The cysteine-rich C-terminal domain of this protein, corresponding to AGRP(87-132), exhibits receptor binding affinity and antagonism equivalent to that of the full-length protein. The NMR structure of this active domain was recently determined and suggested that melanocortin receptor contacts were made primarily by two loops presented by a well-structured cystine knot domain within AGRP(87-132) [McNulty et al. (2001) Biochemistry 40, 15520-15527]. This hypothesis is tested here with NMR structure and activity studies of a 34-residue AGRP analogue designed to contain only the cystine knot domain. The designed miniprotein folds to a homogeneous product, retains the desired cystine knot architecture, functions as an antagonist, and maintains the melanocortin receptor pharmacological profile of AGRP(87-132). The AGRP-like activity of this molecule supports the hypothesis that indeed the cystine knot region possesses the melanocortin receptor contact points. Moreover, this potent AGRP analogue is synthetically accessible, may serve in the development of therapeutics for the treatment of diseases related to energy balance. and may also find use as a new reagent for probing melanocortin receptor structure and function.

  19. TRPA1 contributes to specific mechanically activated currents and sensory neuron mechanical hypersensitivity.

    PubMed

    Brierley, Stuart M; Castro, Joel; Harrington, Andrea M; Hughes, Patrick A; Page, Amanda J; Rychkov, Grigori Y; Blackshaw, L Ashley

    2011-07-15

    The mechanosensory role of TRPA1 and its contribution to mechanical hypersensitivity in sensory neurons remains enigmatic. We elucidated this role by recording mechanically activated currents in conjunction with TRPA1 over- and under-expression and selective pharmacology. First, we established that TRPA1 transcript, protein and functional expression are more abundant in smaller-diameter neurons than larger-diameter neurons, allowing comparison of two different neuronal populations. Utilising whole cell patch clamping, we applied calibrated displacements to neurites of dorsal root ganglion (DRG) neurons in short-term culture and recorded mechanically activated currents termed intermediately (IAMCs), rapidly (RAMCs) or slowly adapting (SAMCs). Trpa1 deletion (–/–) significantly reduced maximum IAMC amplitude by 43% in small-diameter neurons compared with wild-type (+/+) neurons. All other mechanically activated currents in small- and large-diameter Trpa1−/− neurons were unaltered. Seventy-three per cent of Trpa1+/+ small-diameter neurons responding to the TRPA1 agonist allyl-isothiocyanate (AITC) displayed IAMCs to neurite displacement, which were significantly enhanced after AITC addition. The TRPA1 antagonist HC-030031 significantly decreased Trpa1+/+ IAMC amplitudes, but only in AITC responsive neurons. Using a transfection system we also showed TRPA1 over-expression in Trpa1+/+ small-diameter neurons increases IAMC amplitude, an effect reversed by HC-030031. Furthermore, TRPA1 introduction into Trpa1−/− small-diameter neurons restored IAMC amplitudes to Trpa1+/+ levels, which was subsequently reversed by HC-030031. In summary our data demonstrate TRPA1 makes a contribution to normal mechanosensation in a specific subset of DRG neurons. Furthermore, they also provide new evidence illustrating mechanisms by which sensitisation or over-expression of TRPA1 enhances nociceptor mechanosensitivity. Overall, these findings suggest TRPA1 has the capacity to

  20. Firing Behavior and Network Activity of Single Neurons in Human Epileptic Hypothalamic Hamartoma

    PubMed Central

    Steinmetz, Peter N.; Wait, Scott D.; Lekovic, Gregory P.; Rekate, Harold L.; Kerrigan, John F.

    2013-01-01

    Objective: Human hypothalamic hamartomas (HH) are intrinsically epileptogenic and are associated with treatment-resistant gelastic seizures. The basic cellular mechanisms responsible for seizure onset within HH are unknown. We used intra-operative microwire recordings of single neuron activity to measure the spontaneous firing rate of neurons and the degree of functional connection between neurons within the tumor. Technique: Fourteen patients underwent transventricular endoscopic resection of HH for treatment-resistant epilepsy. Prior to surgical resection, single neuron recordings from bundled microwires (total of nine contacts) were obtained from HH tissue. Spontaneous activity was recorded for two or three 5-min epochs under steady-state general anesthesia. Off-line analysis included cluster analysis of single unit activity and probability analysis of firing relationships between pairs of neurons. Results: Altogether, 222 neurons were identified (mean 6 neurons per recording epoch). Cluster analysis of single neuron firing utilizing a mixture of Gaussians model identified two distinct populations on the basis of firing rate (median firing frequency 0.6 versus 15.0 spikes per second; p < 10−5). Cluster analysis identified three populations determined by levels of burst firing (median burst indices of 0.015, 0.18, and 0.39; p < 10−15). Unbiased analysis of spontaneous single unit behavior showed that 51% of all possible neuron pairs within each recording epoch had a significant level of firing synchrony (p < 10−15). The subgroup of neurons with higher median firing frequencies was more likely to demonstrate synchronous firing (p < 10−7). Conclusion: Hypothalamic hamartoma tissue in vivo contains neurons which fire spontaneously. The activity of single neurons is diverse but distributes into at least two electrophysiological phenoytpes. Functional linkage between single neurons suggests that HH neurons exist within local networks that may

  1. TRPA1 contributes to specific mechanically activated currents and sensory neuron mechanical hypersensitivity

    PubMed Central

    Brierley, Stuart M; Castro, Joel; Harrington, Andrea M; Hughes, Patrick A; Page, Amanda J; Rychkov, Grigori Y; Blackshaw, L Ashley

    2011-01-01

    Abstract The mechanosensory role of TRPA1 and its contribution to mechanical hypersensitivity in sensory neurons remains enigmatic. We elucidated this role by recording mechanically activated currents in conjunction with TRPA1 over- and under-expression and selective pharmacology. First, we established that TRPA1 transcript, protein and functional expression are more abundant in smaller-diameter neurons than larger-diameter neurons, allowing comparison of two different neuronal populations. Utilising whole cell patch clamping, we applied calibrated displacements to neurites of dorsal root ganglion (DRG) neurons in short-term culture and recorded mechanically activated currents termed intermediately (IAMCs), rapidly (RAMCs) or slowly adapting (SAMCs). Trpa1 deletion (–/–) significantly reduced maximum IAMC amplitude by 43% in small-diameter neurons compared with wild-type (+/+) neurons. All other mechanically activated currents in small- and large-diameter Trpa1−/− neurons were unaltered. Seventy-three per cent of Trpa1+/+ small-diameter neurons responding to the TRPA1 agonist allyl-isothiocyanate (AITC) displayed IAMCs to neurite displacement, which were significantly enhanced after AITC addition. The TRPA1 antagonist HC-030031 significantly decreased Trpa1+/+ IAMC amplitudes, but only in AITC responsive neurons. Using a transfection system we also showed TRPA1 over-expression in Trpa1+/+ small-diameter neurons increases IAMC amplitude, an effect reversed by HC-030031. Furthermore, TRPA1 introduction into Trpa1−/− small-diameter neurons restored IAMC amplitudes to Trpa1+/+ levels, which was subsequently reversed by HC-030031. In summary our data demonstrate TRPA1 makes a contribution to normal mechanosensation in a specific subset of DRG neurons. Furthermore, they also provide new evidence illustrating mechanisms by which sensitisation or over-expression of TRPA1 enhances nociceptor mechanosensitivity. Overall, these findings suggest TRPA1 has the

  2. Neuronal nicotinic acetylcholine receptor activation modulates gamma-aminobutyric acid release from CA1 neurons of rat hippocampal slices.

    PubMed

    Alkondon, M; Pereira, E F; Barbosa, C T; Albuquerque, E X

    1997-12-01

    In the present study we investigated electrophysiologically the nicotinic responses of pyramidal neurons and interneurons visualized by infrared-assisted videomicroscopy and fluorescence in the CA1 field of hippocampal slices obtained from 8- to 24-day-old rats. Application of nicotinic agonists to CA1 neurons evoked at least four types of nicotinic responses. Of major interest was the ability of these agonists to induce the release of gamma-aminobutyric acid (GABA) from interneurons. Slowly decaying ACh whole-cell currents and GABA-mediated postsynaptic currents could be recorded from pyramidal neurons and interneurons, whereas fast-decaying nicotinic currents and fast current transients were recorded only from interneurons. Nicotinic responses were sensitive to blockade by d-tubocurarine (10 microM), which indicated that they were mediated by nicotinic acetylcholine receptors (nAChRs). The slowly decaying currents, the postsynaptic currents and the fast current transients were insensitive to blockade by the alpha-7 nAChR-specific antagonist methyllycaconitine (up to 1 microM) or alpha-bungarotoxin (100 nM). On the other hand, the slowly decaying nicotinic currents recorded from the interneurons were blocked by the alpha4beta2 nAChR-specific antagonist dihydro-beta-erythroidine, and the fast-desensitizing nicotinic currents were evoked by the alpha-7 nAChR-specific agonist choline. In experimental conditions similar to those used to record nicotinic responses from neurons in slice (i. e., in the absence of tetrodotoxin), we observed that nicotinic agonists can also induce the release of GABA from hippocampal neurons in culture. In summary, these results provide direct evidence for more than one subtype of functional nAChR in CA1 neurons and suggest that activation of nAChRs present in GABAergic interneurons can evoke inhibitory activity in CA1 pyramidal neurons, thereby modulating processing of information in the hippocampus.

  3. ELF-magnetic field induced effects on the bioelectric activity of single neurone cells

    NASA Astrophysics Data System (ADS)

    Azanza, Maria J.; del Moral, A.

    1998-01-01

    The membrane bioelectric activity recorded from single neurones is dramatically modified under applied extremely low frequency magnetic fields (ELF-MF) of 50 Hz and 1-15 mT peak intensity. In ≌27% of the neurones studied a firing rhythm is generated for ≌7 mT, which resembles synchronous oscillations activity. The possibility that ELF-MF could generate neuronal networks synchrony firing does exist as an explanatory physical model shows.

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

    PubMed

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

    2015-05-01

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

  5. Opposing Effects of Neuronal Activity on Structural Plasticity

    PubMed Central

    Fauth, Michael; Tetzlaff, Christian

    2016-01-01

    The connectivity of the brain is continuously adjusted to new environmental influences by several activity-dependent adaptive processes. The most investigated adaptive mechanism is activity-dependent functional or synaptic plasticity regulating the transmission efficacy of existing synapses. Another important but less prominently discussed adaptive process is structural plasticity, which changes the connectivity by the formation and deletion of synapses. In this review, we show, based on experimental evidence, that structural plasticity can be classified similar to synaptic plasticity into two categories: (i) Hebbian structural plasticity, which leads to an increase (decrease) of the number of synapses during phases of high (low) neuronal activity and (ii) homeostatic structural plasticity, which balances these changes by removing and adding synapses. Furthermore, based on experimental and theoretical insights, we argue that each type of structural plasticity fulfills a different function. While Hebbian structural changes enhance memory lifetime, storage capacity, and memory robustness, homeostatic structural plasticity self-organizes the connectivity of the neural network to assure stability. However, the link between functional synaptic and structural plasticity as well as the detailed interactions between Hebbian and homeostatic structural plasticity are more complex. This implies even richer dynamics requiring further experimental and theoretical investigations. PMID:27445713

  6. Spontaneous Neuronal Activity in Developing Neocortical Networks: From Single Cells to Large-Scale Interactions

    PubMed Central

    Luhmann, Heiko J.; Sinning, Anne; Yang, Jenq-Wei; Reyes-Puerta, Vicente; Stüttgen, Maik C.; Kirischuk, Sergei; Kilb, Werner

    2016-01-01

    Neuronal activity has been shown to be essential for the proper formation of neuronal circuits, affecting developmental processes like neurogenesis, migration, programmed cell death, cellular differentiation, formation of local and long-range axonal connections, synaptic plasticity or myelination. Accordingly, neocortical areas reveal distinct spontaneous and sensory-driven neuronal activity patterns already at early phases of development. At embryonic stages, when immature neurons start to develop voltage-dependent channels, spontaneous activity is highly synchronized within small neuronal networks and governed by electrical synaptic transmission. Subsequently, spontaneous activity patterns become more complex, involve larger networks and propagate over several neocortical areas. The developmental shift from local to large-scale network activity is accompanied by a gradual shift from electrical to chemical synaptic transmission with an initial excitatory action of chloride-gated channels activated by GABA, glycine and taurine. Transient neuronal populations in the subplate (SP) support temporary circuits that play an important role in tuning early neocortical activity and the formation of mature neuronal networks. Thus, early spontaneous activity patterns control the formation of developing networks in sensory cortices, and disturbances of these activity patterns may lead to long-lasting neuronal deficits. PMID:27252626

  7. Sonogenetics is a non-invasive approach to activating neurons in Caenorhabditis elegans

    PubMed Central

    Ibsen, Stuart; Tong, Ada; Schutt, Carolyn; Esener, Sadik; Chalasani, Sreekanth H.

    2015-01-01

    A major challenge in neuroscience is to reliably activate individual neurons, particularly those in deeper brain regions. Current optogenetic approaches require invasive surgical procedures to deliver light of specific wavelengths to target cells to activate or silence them. Here, we demonstrate the use of low-pressure ultrasound as a non-invasive trigger to activate specific ultrasonically sensitized neurons in the nematode, Caenorhabditis elegans. We first show that wild-type animals are insensitive to low-pressure ultrasound and require gas-filled microbubbles to transduce the ultrasound wave. We find that neuron-specific misexpression of TRP-4, the pore-forming subunit of a mechanotransduction channel, sensitizes neurons to ultrasound stimulus, resulting in behavioural outputs. Furthermore, we use this approach to manipulate the function of sensory neurons and interneurons and identify a role for PVD sensory neurons in modifying locomotory behaviours. We suggest that this method can be broadly applied to manipulate cellular functions in vivo. PMID:26372413

  8. Light Activates Output from Evening Neurons and Inhibits Output from Morning Neurons in the Drosophila Circadian Clock

    PubMed Central

    Picot, Marie; Cusumano, Paola; Klarsfeld, André; Ueda, Ryu; Rouyer, François

    2007-01-01

    Animal circadian clocks are based on multiple oscillators whose interactions allow the daily control of complex behaviors. The Drosophila brain contains a circadian clock that controls rest–activity rhythms and relies upon different groups of PERIOD (PER)–expressing neurons. Two distinct oscillators have been functionally characterized under light-dark cycles. Lateral neurons (LNs) that express the pigment-dispersing factor (PDF) drive morning activity, whereas PDF-negative LNs are required for the evening activity. In constant darkness, several lines of evidence indicate that the LN morning oscillator (LN-MO) drives the activity rhythms, whereas the LN evening oscillator (LN-EO) does not. Since mutants devoid of functional CRYPTOCHROME (CRY), as opposed to wild-type flies, are rhythmic in constant light, we analyzed transgenic flies expressing PER or CRY in the LN-MO or LN-EO. We show that, under constant light conditions and reduced CRY function, the LN evening oscillator drives robust activity rhythms, whereas the LN morning oscillator does not. Remarkably, light acts by inhibiting the LN-MO behavioral output and activating the LN-EO behavioral output. Finally, we show that PDF signaling is not required for robust activity rhythms in constant light as opposed to its requirement in constant darkness, further supporting the minor contribution of the morning cells to the behavior in the presence of light. We therefore propose that day–night cycles alternatively activate behavioral outputs of the Drosophila evening and morning lateral neurons. PMID:18044989

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

    PubMed Central

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

    2014-01-01

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

  10. Subpopulations of rat dorsal root ganglion neurons express active vesicular acetylcholine transporter.

    PubMed

    Tata, Ada Maria; De Stefano, M Egle; Tomassy, Giulio Srubek; Vilaró, M Teresa; Levey, Allan I; Biagioni, Stefano

    2004-01-15

    The vesicular acetylcholine transporter (VAChT) is a transmembrane protein required, in cholinergic neurons, for selective storage of acetylcholine into synaptic vesicles. Although dorsal root ganglion (DRG) neurons utilize neuropeptides and amino acids for neurotransmission, we have previously demonstrated the presence of a cholinergic system. To investigate whether, in sensory neurons, the vesicular accumulation of acetylcholine relies on the same mechanisms active in classical cholinergic neurons, we investigated VAChT presence, subcellular distribution, and activity. RT-PCR and Western blot analysis demonstrated the presence of VAChT mRNA and protein product in DRG neurons and in the striatum and cortex, used as positive controls. Moreover, in situ hybridization and immunocytochemistry showed VAChT staining located mainly in the medium/large-sized subpopulation of the sensory neurons. A few small neurons were also faintly labeled by immunocytochemistry. In the electron microscope, immunolabeling was associated with vesicle-like elements distributed in the neuronal cytoplasm and in both myelinated and unmyelinated intraganglionic nerve fibers. Finally, [(3)H]acetylcholine active transport, evaluated either in the presence or in the absence of ATP, also demonstrated that, as previously reported, the uptake of acetylcholine by VAChT is ATP dependent. This study suggests that DRG neurons not only are able to synthesize and degrade ACh and to convey cholinergic stimuli but also are capable of accumulating and, possibly, releasing acetylcholine by the same mechanism used by the better known cholinergic neurons.

  11. Selective regulation of current densities underlies spontaneous changes in the activity of cultured neurons.

    PubMed

    Turrigiano, G; LeMasson, G; Marder, E

    1995-05-01

    We study the electrical activity patterns and the expression of conductances in adult stomatogastric ganglion (STG) neurons as a function of time in primary cell culture. When first plated in culture, these neurons had few active properties. After 1 d in culture they produced small action potentials that rapidly inactivated during maintained depolarization. After 2 d in culture they fired large action potentials tonically when depolarized, and their properties resembled very closely the properties of STG neurons pharmacologically isolated in the ganglion. After 3-4 d in culture, however, their electrical properties changed and they fired in bursts when depolarized. We characterized the currents expressed by these neurons in culture. They included two TTX-sensitive sodium currents, a calcium current, a delayed-rectifier-like current, a calcium-dependent potassium current, and two A-type currents. The changes in firing properties with time in culture were accompanied by an increase in inward and decrease in outward current densities. A single-compartment conductance-based model of an STG neuron was constructed by fitting the currents measured in the biological neurons. When the current densities in the model neuron were matched to those measured for the biological neurons in each activity state, the model neuron closely reproduced each state, indicating that the changes in current densities are sufficient to account for the changes in intrinsic properties. These data indicate that STG neurons isolated in culture change their intrinsic electrical properties by selectively adjusting the magnitudes of their ionic conductances.

  12. Peripherally injected CCK-8S activates CART positive neurons of the paraventricular nucleus in rats

    PubMed Central

    Noetzel, Steffen; Inhoff, Tobias; Goebel, Miriam; Taché, Yvette; Veh, Rüdiger W.; Bannert, Norbert; Grötzinger, Carsten; Wiedenmann, Bertram; Klapp, Burghard F.; Mönnikes, Hubert; Kobelt, Peter

    2014-01-01

    Cholecystokinin (CCK) plays a role in the short-term inhibition of food intake. Cocaine- and amphetamine-regulated transcript (CART) peptide has been observed in neurons of the paraventricular nucleus (PVN). It has been reported that intracerebroventricular injection of CART peptide inhibits food intake in rodents. The aim of the study was to determine whether intraperitoneally (ip) injected CCK-8S affects neuronal activity of PVN-CART neurons. Ad libitum fed male Sprague-Dawley rats received 6 or 10 μg/kg CCK-8S or 0.15 M NaCl ip (n = 4/group). The number of c-Fos-immunoreactive neurons was determined in the PVN, arcuate nucleus (ARC), and the nucleus of the solitary tract (NTS). CCK-8S dose-dependently increased the number of c-Fos-immunoreactive neurons in the PVN (mean ± SEM: 102 ± 6 vs. 150 ± 5 neurons/section, p < 0.05) and compared to vehicle treated rats (18 ± 7, p < 0.05 vs. 6 and 10 μg/kg CCK-8S). CCK-8S at both doses induced an increase in the number of c-Fos-immunoreactive neurons in the NTS (65 ± 13, p < 0.05, and 182 ± 16, p < 0.05). No effect on the number of c-Fos neurons was observed in the ARC. Immunostaining for CART and c-Fos revealed a dose-dependent increase of activated CART neurons (19 ± 3 vs. 29 ± 7; p < 0.05), only few activated CART neuron were observed in the vehicle group (1 ± 0). The present observation shows that CCK-8S injected ip induces an increase in neuronal activity in PVN-CART neurons and suggests that CART neurons in the PVN may play a role in the mediation of peripheral CCK-8S's anorexigenic effects. PMID:20307613

  13. Transgenic Activation of Ras in Neurons Promotes Hypertrophy and Protects from Lesion-Induced Degeneration

    PubMed Central

    Heumann, Rolf; Goemans, Christoph; Bartsch, Daniela; Lingenhöhl, Kurt; Waldmeier, Peter C.; Hengerer, Bastian; Allegrini, Peter R.; Schellander, Karl; Wagner, Erwin F.; Arendt, Thomas; Kamdem, Rigobert H.; Obst-Pernberg, Kirstin; Narz, Frank; Wahle, Petra; Berns, Hartmut

    2000-01-01

    Ras is a universal eukaryotic intracellular protein integrating extracellular signals from multiple receptor types. To investigate its role in the adult central nervous system, constitutively activated V12-Ha-Ras was expressed selectively in neurons of transgenic mice via a synapsin promoter. Ras-transgene protein expression increased postnatally, reaching a four- to fivefold elevation at day 40 and persisting at this level, thereafter. Neuronal Ras was constitutively active and a corresponding activating phosphorylation of mitogen-activated kinase was observed, but there were no changes in the activity of phosphoinositide 3-kinase, the phosphorylation of its target kinase Akt/PKB, or expression of the anti-apoptotic proteins Bcl-2 or Bcl-XL. Neuronal Ras activation did not alter the total number of neurons, but induced cell soma hypertrophy, which resulted in a 14.5% increase of total brain volume. Choline acetyltransferase and tyrosine hydroxylase activities were increased, as well as neuropeptide Y expression. Degeneration of motorneurons was completely prevented after facial nerve lesion in Ras-transgenic mice. Furthermore, neurotoxin-induced degeneration of dopaminergic substantia nigra neurons and their striatal projections was greatly attenuated. Thus, the Ras signaling pathway mimics neurotrophic effects and triggers neuroprotective mechanisms in adult mice. Neuronal Ras activation might become a tool to stabilize donor neurons for neural transplantation and to protect neuronal populations in neurodegenerative diseases. PMID:11134081

  14. Cultured Neuronal Networks Express Complex Patterns of Activity and Morphological Memory

    NASA Astrophysics Data System (ADS)

    Raichman, Nadav; Rubinsky, Liel; Shein, Mark; Baruchi, Itay; Volman, Vladislav; Ben-Jacob, Eshel

    The following sections are included: * Cultured Neuronal Networks * Recording the Network Activity * Network Engineering * The Formation of Synchronized Bursting Events * The Characterization of the SBEs * Highly-Active Neurons * Function-Form Relations in Cultured Networks * Analyzing the SBEs Motifs * Network Repertoire * Network under Hypothermia * Summary * Acknowledgments * References

  15. Insulin Excites Anorexigenic Proopiomelanocortin Neurons via Activation of Canonical Transient Receptor Potential Channels

    PubMed Central

    Qiu, Jian; Zhang, Chunguang; Borgquist, Amanda; Nestor, Casey C; Smith, Arik W.; Bosch, Martha A.; Ku, Stephen; Wagner, Edward J.; Rønnekleiv, Oline K.; Kelly, Martin J.

    2014-01-01

    SUMMARY Proopiomelanocortin (POMC) neurons within the hypothalamic arcuate nucleus are vital anorexigenic neurons. Although both the leptin receptor and insulin receptor are coupled to activation of phosphatidylinositide3-kinase (PI3K) in POMC neurons, they are thought to have disparate actions on POMC excitability. Using whole-cell recording and selective pharmacological tools, we have found that similar to leptin, purified insulin depolarized POMC, and adjacent kisspeptin neurons via activation of TRPC5 channels, which are highly expressed in these neurons. In contrast, insulin hyperpolarized and inhibited NPY/AgRP neurons via activation of KATP channels. Moreover, Zn2+, which is found in insulin formulations at nanomolar concentrations, inhibited POMC neurons via activation of KATP channels. Finally as predicted, insulin given intracerebroventrically robustly inhibited food intake and activated c-fos expression in arcuate POMC neurons. Our results show that purified insulin excites POMC neurons in the arcuate nucleus, which we propose is a major mechanism by which insulin regulates energy homeostasis. PMID:24703699

  16. Multi-channel fiber photometry for population neuronal activity recording.

    PubMed

    Guo, Qingchun; Zhou, Jingfeng; Feng, Qiru; Lin, Rui; Gong, Hui; Luo, Qingming; Zeng, Shaoqun; Luo, Minmin; Fu, Ling

    2015-10-01

    Fiber photometry has become increasingly popular among neuroscientists as a convenient tool for the recording of genetically defined neuronal population in behaving animals. Here, we report the development of the multi-channel fiber photometry system to simultaneously monitor neural activities in several brain areas of an animal or in different animals. In this system, a galvano-mirror modulates and cyclically couples the excitation light to individual multimode optical fiber bundles. A single photodetector collects excited light and the configuration of fiber bundle assembly and the scanner determines the total channel number. We demonstrated that the system exhibited negligible crosstalk between channels and optical signals could be sampled simultaneously with a sample rate of at least 100 Hz for each channel, which is sufficient for recording calcium signals. Using this system, we successfully recorded GCaMP6 fluorescent signals from the bilateral barrel cortices of a head-restrained mouse in a dual-channel mode, and the orbitofrontal cortices of multiple freely moving mice in a triple-channel mode. The multi-channel fiber photometry system would be a valuable tool for simultaneous recordings of population activities in different brain areas of a given animal and different interacting individuals.

  17. Atomic basis for therapeutic activation of neuronal potassium channels

    PubMed Central

    Kim, Robin Y.; Yau, Michael C.; Galpin, Jason D.; Seebohm, Guiscard; Ahern, Christopher A.; Pless, Stephan A.; Kurata, Harley T.

    2015-01-01

    Retigabine is a recently approved anticonvulsant that acts by potentiating neuronal M-current generated by KCNQ2–5 channels, interacting with a conserved Trp residue in the channel pore domain. Using unnatural amino-acid mutagenesis, we subtly altered the properties of this Trp to reveal specific chemical interactions required for retigabine action. Introduction of a non-natural isosteric H-bond-deficient Trp analogue abolishes channel potentiation, indicating that retigabine effects rely strongly on formation of a H-bond with the conserved pore Trp. Supporting this model, substitution with fluorinated Trp analogues, with increased H-bonding propensity, strengthens retigabine potency. In addition, potency of numerous retigabine analogues correlates with the negative electrostatic surface potential of a carbonyl/carbamate oxygen atom present in most KCNQ activators. These findings functionally pinpoint an atomic-scale interaction essential for effects of retigabine and provide stringent constraints that may guide rational improvement of the emerging drug class of KCNQ channel activators. PMID:26333338

  18. Cortical neuronal activity does not regulate sleep homeostasis.

    PubMed

    Qiu, M-H; Chen, M C; Lu, J

    2015-06-25

    The neural substrate of sleep homeostasis is unclear, but both cortical and subcortical structures are thought to be involved in sleep regulation. To test whether prior neuronal activity in the cortex or in subcortical regions drives sleep rebound, we systemically administered atropine (100mg/kg) to rats, producing a dissociated state with slow-wave cortical electroencephalogram (EEG) but waking behavior (e.g. locomotion). Atropine injections during the light period produced 6h of slow-wave cortical EEG but also subcortical arousal. Afterward, rats showed a significant increase in non-rapid eye movement (NREM) sleep, compared to the same period on a baseline day. Consistent with the behavioral and cortical EEG state produced by systemic atropine, c-Fos expression was low in the cortex but high in multiple subcortical arousal systems. These data suggest that subcortical arousal and behavior are sufficient to drive sleep homeostasis, while a sleep-like pattern of cortical activity is not sufficient to satisfy sleep homeostasis.

  19. IGF-1 Induces GHRH Neuronal Axon Elongation during Early Postnatal Life in Mice

    PubMed Central

    Clemessy, Maud; Heurtier, Victor; Ledent, Tatiana; Robinson, Iain C.; Mollard, Patrice; Epelbaum, Jacques; Meaney, Michael J.; Garel, Sonia; Le Bouc, Yves; Kappeler, Laurent

    2017-01-01

    Nutrition during the perinatal period programs body growth. Growth hormone (GH) secretion from the pituitary regulates body growth and is controlled by Growth Hormone Releasing Hormone (GHRH) neurons located in the arcuate nucleus of the hypothalamus. We observed that dietary restriction during the early postnatal period (i.e. lactation) in mice influences postnatal growth by permanently altering the development of the somatotropic axis in the pituitary gland. This alteration may be due to a lack of GHRH signaling during this critical developmental period. Indeed, underfed pups showed decreased insulin-like growth factor I (IGF-I) plasma levels, which are associated with lower innervation of the median eminence by GHRH axons at 10 days of age relative to normally fed pups. IGF-I preferentially stimulated axon elongation of GHRH neurons in in vitro arcuate explant cultures from 7 day-old normally fed pups. This IGF-I stimulating effect was selective since other arcuate neurons visualized concomitantly by neurofilament labeling, or AgRP immunochemistry, did not significantly respond to IGF-I stimulation. Moreover, GHRH neurons in explants from age-matched underfed pups lost the capacity to respond to IGF-I stimulation. Molecular analyses indicated that nutritional restriction was associated with impaired activation of AKT. These results highlight a role for IGF-I in axon elongation that appears to be cell selective and participates in the complex cellular mechanisms that link underfeeding during the early postnatal period with programming of the growth trajectory. PMID:28076448

  20. Transient Activation of GABAB Receptors Suppresses SK Channel Currents in Substantia Nigra Pars Compacta Dopaminergic Neurons

    PubMed Central

    Estep, Chad M.; Galtieri, Daniel J.; Zampese, Enrico; Goldberg, Joshua A.; Brichta, Lars; Greengard, Paul; Surmeier, D. James

    2016-01-01

    Dopaminergic (DA) neurons in the substantia nigra pars compacta (SNc) are richly innervated by GABAergic neurons. The postsynaptic effects of GABA on SNc DA neurons are mediated by a mixture of GABAA and GABAB receptors. Although activation of GABAA receptors inhibits spike generation, the consequences of GABAB receptor activation are less well characterized. To help fill this gap, perforated patch recordings were made from young adult mouse SNc DA neurons. Sustained stimulation of GABAB receptors hyperpolarized SNc DA neurons, as previously described. However, transient stimulation of GABAB receptors by optical uncaging of GABA did not; rather, it reduced the opening of small-conductance, calcium-activated K+ (SK) channels and increased the irregularity of spiking. This modulation was attributable to inhibition of adenylyl cyclase and protein kinase A. Thus, because suppression of SK channel activity increases the probability of burst spiking, transient co-activation of GABAA and GABAB receptors could promote a pause-burst pattern of spiking. PMID:28036359

  1. Structure-activity relationship of sulfated hetero/galactofucan polysaccharides on dopaminergic neuron.

    PubMed

    Wang, Jing; Liu, Huaide; Jin, Weihua; Zhang, Hong; Zhang, Quanbin

    2016-01-01

    Parkinson's disease (PD) is associated with progressive loss of dopaminergic neurons and more-widespread neuronal changes that cause complex symptoms. The aim of this study was to investigate the structure-activity relationship of sulfated hetero-polysaccharides (DF1) and sulfated galactofucan polysaccharides (DF2) on dopaminergic neuron in vivo and in vitro. Treatment with samples significantly ameliorated the depletion of both DA and TH-, Bcl-2- and Bax-positive neurons in MPTP-induced PD mice, DF1 showed the highest activity. The in vitro results found that DF1 and DF2 could reverse the decreased mitochondrial activity and the increased LDL release induced by MPP(+) (P<0.01 or P<0.001) which provides further evidence that DF1 and DF2 also exerts a direct protection against the neuronal injury caused by MPP(+). Furthermore, the administration of samples effectively decreased lipid peroxidation and increased the level/activities of GSH, GSH-PX, MDA and CAT in MPTP mice. Thus, the neuron protective effect may be mediated, in part, through antioxidant activity and the prevention of cell apoptosis. The chemical composition of DF1, DF2 and DF differed markedly, the DF1 fraction had the most complex chemical composition and showed the highest neuron protective activity. These results suggest that diverse monosaccharides and uronic acid might contribute to neuron protective activity.

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

    PubMed Central

    Keller, Corey J.; Khodakhah, Kamran

    2016-01-01

    To date, single neuron recordings remain the gold standard for monitoring the activity of neuronal populations. Since obtaining single neuron recordings is not always possible, high frequency or ‘multiunit activity’ (MUA) is often used as a surrogate. Although MUA recordings allow one to monitor the activity of a large number of neurons, they do not allow identification of specific neuronal subtypes, the knowledge of which is often critical for understanding electrophysiological processes. Here, we explored whether prior knowledge of the single unit waveform of specific neuron types is sufficient to permit the use of MUA to monitor and distinguish differential activity of individual neuron types. We used an experimental and modeling approach to determine if components of the MUA can monitor medium spiny neurons (MSNs) and fast-spiking interneurons (FSIs) in the mouse dorsal striatum. We demonstrate that when well-isolated spikes are recorded, the MUA at frequencies greater than 100Hz is correlated with single unit spiking, highly dependent on the waveform of each neuron type, and accurately reflects the timing and spectral signature of each neuron. However, in the absence of well-isolated spikes (the norm in most MUA recordings), the MUA did not typically contain sufficient information to permit accurate prediction of the respective population activity of MSNs and FSIs. Thus, even under ideal conditions for the MUA to reliably predict the moment-to-moment activity of specific local neuronal ensembles, knowledge of the spike waveform of the underlying neuronal populations is necessary, but not sufficient. PMID:27111446

  3. Hypoglycemia-activated GLUT2 neurons of the nucleus tractus solitarius stimulate vagal activity and glucagon secretion.

    PubMed

    Lamy, Christophe M; Sanno, Hitomi; Labouèbe, Gwenaël; Picard, Alexandre; Magnan, Christophe; Chatton, Jean-Yves; Thorens, Bernard

    2014-03-04

    Glucose-sensing neurons in the brainstem participate in the regulation of energy homeostasis but have been poorly characterized because of the lack of specific markers to identify them. Here we show that GLUT2-expressing neurons of the nucleus of the tractus solitarius form a distinct population of hypoglycemia-activated neurons. Their response to low glucose is mediated by reduced intracellular glucose metabolism, increased AMP-activated protein kinase activity, and closure of leak K(+) channels. These are GABAergic neurons that send projections to the vagal motor nucleus. Light-induced stimulation of channelrhodospin-expressing GLUT2 neurons in vivo led to increased parasympathetic nerve firing and glucagon secretion. Thus GLUT2 neurons of the nucleus tractus solitarius link hypoglycemia detection to counterregulatory response. These results may help identify the cause of hypoglycemia-associated autonomic failure, a major threat in the insulin treatment of diabetes.

  4. Electrophysiological and pharmacological properties of locomotor activity-related neurons in cfos-EGFP mice.

    PubMed

    Dai, Yue; Carlin, Kevin P; Li, Zongming; McMahon, Douglas G; Brownstone, Robert M; Jordan, Larry M

    2009-12-01

    Although locomotion is known to be generated by networks of spinal neurons, knowledge of the properties of these neurons is limited. Using neonatal transgenic mice that express enhanced green fluorescent protein (EGFP) driven by the c-fos promoter, we visualized EGFP-positive neurons in spinal cord slices from animals that were subjected to a locomotor task or drug cocktail [N-methyl-D-aspartate, serotonin (5-HT), dopamine, and acetylcholine (ACh)]. The activity-dependent expression of EGFP was also induced in dorsal root ganglion neurons with electrical stimulation of the neurons. Following 60-90 min of swimming, whole cell patch-clamp recordings were made from EGFP+ neurons in laminae VII, VIII, and X from slices of segments T(12) to L(4). The EGFP+ neurons (n = 55) could be classified into three types based on their responses to depolarizing step currents: single spike, phasic firing, and tonic firing. Membrane properties observed in these neurons include hyperpolarization-activated inward currents (29/55), postinhibitory rebound (11/55), and persistent-inward currents (31/55). Bath application of 10-40 microM 5-HT and/or ACh increased neuronal excitability or output with hyperpolarization of voltage threshold and changes in membrane potential. 5-HT also increased input resistance, reduced the afterhyperpolarization (AHP), and induced membrane oscillations, whereas ACh reduced the input resistance and increased the AHP. In this study, we demonstrate a new way of identifying neurons active in locomotion. Our results suggest that the EGFP+ neurons are a heterogeneous population of interneurons. The actions of 5-HT and ACh on these neurons provide insights into the neuronal properties modulated by these transmitters for generation of locomotion.

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

    PubMed

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

    2015-06-03

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

  6. Variations in Acetylcholinesterase Activity within Human Cortical Pyramidal Neurons Across Age and Cognitive Trajectories.

    PubMed

    Janeczek, Monica; Gefen, Tamar; Samimi, Mehrnoosh; Kim, Garam; Weintraub, Sandra; Bigio, Eileen; Rogalski, Emily; Mesulam, M-Marsel; Geula, Changiz

    2017-03-01

    We described an extensive network of cortical pyramidal neurons in the human brain with abundant acetylcholinesterase (AChE) activity. Emergence of these neurons during childhood/adolescence, attainment of highest density in early adulthood, and virtual absence in other species led us to hypothesize involvement of AChE within these neurons in higher cortical functions. The current study quantified the density and staining intensity of these neurons using histochemical procedures. Few faintly stained AChE-positive cortical pyramidal neurons were observed in children/adolescents. These neurons attained their highest density and staining intensity in young adulthood. Compared with the young adult group, brains of cognitively normal elderly displayed no significant change in numerical density but a significant decrease in staining intensity of AChE-positive cortical pyramidal neurons. Brains of elderly above age 80 with unusually preserved memory performance (SuperAgers) showed significantly lower staining intensity and density of these neurons when compared with same-age peers. Conceivably, low levels of AChE activity could enhance the impact of acetylcholine on pyramidal neurons to counterbalance other involutional factors that mediate the decline of memory capacity during average aging. We cannot yet tell if elderly with superior memory capacity have constitutively low neuronal AChE levels or if this feature reflects adaptive neuroplasticity.

  7. Suckling-induced activation of neuronal input to the dorsomedial nucleus of the hypothalamus: possible candidates for mediating the activation of DMH neuropeptide Y neurons during lactation.

    PubMed

    Chen, Peilin; Smith, M Susan

    2003-09-12

    Activation of the neuropeptide Y (NPY) neuronal system in the dorsomedial nucleus of the hypothalamus (DMH) during lactation in the rat is in part due to neural impulses arising from the suckling stimulus. However, the afferent neuronal input to the DMH that is activated during lactation and is responsible for activation of NPY neurons is currently unknown. Previously, using cFos as a marker for neuronal activation, we identified several brain areas in the lactating animals that were activated by the suckling stimulus. Thus, the objective of the present study was to determine if any of these suckling activated areas project directly to the DMH. The retrograde tracer, fluorogold (FG), was injected into the DMH on day 4 postpartum. FG-injected lactating rats were then deprived of their eight-pup litters on day 9 postpartum, and 48 h later, the pups were returned to the females to reinitiate the suckling stimulus for 90 min and induce cFos expression. The animals were then perfused and the brains were subjected to double-label immunohistochemistry to visualize both FG- and cFos-positive cells. Substantial numbers of FG/cFos double-labeled cells were found in forebrain regions, including the preoptic area, lateral septal nucleus, ventral subiculum, and supramammillary nucleus, and in brainstem regions, including the lateral parabrachial nucleus, periaqeductal gray, and ventrolateral medulla. In conclusion, these areas are potentially important candidates for mediating the activation of the NPY neuronal system in the DMH during lactation.

  8. GLT-1 Promoter Activity in Astrocytes and Neurons of Mouse Hippocampus and Somatic Sensory Cortex

    PubMed Central

    de Vivo, Luisa; Melone, Marcello; Rothstein, Jeffrey D.; Conti, Fiorenzo

    2009-01-01

    GLT-1 eGFP BAC reporter transgenic adult mice were used to detect GLT-1 gene expression in individual cells of CA1, CA3 and SI, and eGFP fluorescence was measured to analyze quantitatively GLT-1 promoter activity in different cells of neocortex and hippocampus. Virtually all GFAP+ astrocytes were eGFP+; we also found that about 80% of neurons in CA3 pyramidal layer, 10–70% of neurons in I-VI layers of SI and rare neurons in all strata of CA1 and in strata oriens and radiatum of CA3 were eGFP+. Analysis of eGFP intensity showed that astrocytes had a higher GLT-1 promoter activity in SI than in CA1 and CA3, and that neurons had the highest levels of GLT-1 promoter activity in CA3 stratum pyramidale and in layer VI of SI. Finally, we observed that the intensity of GLT-1 promoter activity in neurons is 1–20% of that measured in astrocytes. These results showed that in the hippocampus and neocortex GLT-1 promoter activity is observed in astrocytes and neurons, detailed the distribution of GLT-1 expressing neurons, and indicated that GLT-1 promoter activity in both astrocytes and neurons varies in different brain regions. PMID:20161698

  9. Persistently active neurons in human medial frontal and medial temporal lobe support working memory.

    PubMed

    Kamiński, Jan; Sullivan, Shannon; Chung, Jeffrey M; Ross, Ian B; Mamelak, Adam N; Rutishauser, Ueli

    2017-04-01

    Persistent neural activity is a putative mechanism for the maintenance of working memories. Persistent activity relies on the activity of a distributed network of areas, but the differential contribution of each area remains unclear. We recorded single neurons in the human medial frontal cortex and medial temporal lobe while subjects held up to three items in memory. We found persistently active neurons in both areas. Persistent activity of hippocampal and amygdala neurons was stimulus-specific, formed stable attractors and was predictive of memory content. Medial frontal cortex persistent activity, on the other hand, was modulated by memory load and task set but was not stimulus-specific. Trial-by-trial variability in persistent activity in both areas was related to memory strength, because it predicted the speed and accuracy by which stimuli were remembered. This work reveals, in humans, direct evidence for a distributed network of persistently active neurons supporting working memory maintenance.

  10. Regular theta-firing neurons in the nucleus incertus during sustained hippocampal activation.

    PubMed

    Martínez-Bellver, Sergio; Cervera-Ferri, Ana; Martínez-Ricós, Joana; Ruiz-Torner, Amparo; Luque-Garcia, Aina; Luque-Martinez, Aina; Blasco-Serra, Arantxa; Guerrero-Martínez, Juan; Bataller-Mompeán, Manuel; Teruel-Martí, Vicent

    2015-04-01

    This paper describes the existence of theta-coupled neuronal activity in the nucleus incertus (NI). Theta rhythm is relevant for cognitive processes such as spatial navigation and memory processing, and can be recorded in a number of structures related to the hippocampal activation including the NI. Strong evidence supports the role of this tegmental nucleus in neural circuits integrating behavioural activation with the hippocampal theta rhythm. Theta oscillations have been recorded in the local field potential of the NI, highly coupled to the hippocampal waves, although no rhythmical activity has been reported in neurons of this nucleus. The present work analyses the neuronal activity in the NI in conditions leading to sustained hippocampal theta in the urethane-anaesthetised rat, in order to test whether such activation elicits a differential firing pattern. Wavelet analysis has been used to better define the neuronal activity already described in the nucleus, i.e., non-rhythmical neurons firing at theta frequency (type I neurons) and fast-firing rhythmical neurons (type II). However, the most remarkable finding was that sustained stimulation activated regular-theta neurons (type III), which were almost silent in baseline conditions and have not previously been reported. Thus, we describe the electrophysiological properties of type III neurons, focusing on their coupling to the hippocampal theta. Their spike rate, regularity and phase locking to the oscillations increased at the beginning of the stimulation, suggesting a role in the activation or reset of the oscillation. Further research is needed to address the specific contribution of these neurons to the entire circuit.

  11. Activity of putative oxytocin neurones during reflex milk ejection in conscious rabbits.

    PubMed Central

    Paisley, A C; Summerlee, A J

    1984-01-01

    Extracellular electrical recordings were taken from twenty antidromically identified paraventricular neurones in unanaesthetized, unrestrained rabbits. Neuronal activity was correlated with nursing behaviour of the doe and responses of the young during suckling. Magnocellular neurones were divided into two groups on the basis of their activity in suckling. Group 1 (n = 14) showed several discrete bursts of high-frequency activity whilst neurones in group 2 (n = 6) did not. Neurones in group 1 showed 5-9 bursts of high-frequency activity in suckling. Each burst lasted 1-4 s and represented a 3-10-fold rise in the discharge of the cell. These units were classified as oxytocinergic, as their stereotyped activation preceded bouts of sucking behaviour of the young indicative of milk ejection. All fourteen cells continued to show intermittent bursts of neurosecretory activity for up to 20 min after nursing terminated. This pattern of discharge followed grooming behaviour of the doe. In contrast, neurones in group 2 (n = 6) showed no high-frequency activity in suckling. They showed a significant fall in their discharge frequency compared with pre-suckling values (P less than 0.05; Student's t test) and a significant (P less than 0.05) lengthening of the modal interspike interval. They were classed as potential vasopressin-producing cells. Control recordings were taken from thirty-two neurones which could not be antidromically driven. The recording sites were shown histologically to be in the lateral hypothalamic area. These cells showed a significant fall in their discharge frequency (P less than 0.05) and a significant increase (P less than 0.01) in the modal interval during suckling. Cross-correlation studies of the activity, recorded from one electrode, of groups of neurones clustered around a single hypothalamic neurone suggest that bursting discharge from the putative oxytocin neurones in suckling is accompanied by the synchronous activation of some of the

  12. ATP Released by Injured Neurons Activates Schwann Cells

    PubMed Central

    Negro, Samuele; Bergamin, Elisanna; Rodella, Umberto; Duregotti, Elisa; Scorzeto, Michele; Jalink, Kees; Montecucco, Cesare; Rigoni, Michela

    2016-01-01

    Injured nerve terminals of neuromuscular junctions (NMJs) can regenerate. This remarkable and complex response is governed by molecular signals that are exchanged among the cellular components of this synapse: motor axon nerve terminal (MAT), perisynaptic Schwann cells (PSCs), and muscle fiber. The nature of signals that govern MAT regeneration is ill-known. In the present study the spider toxin α-latrotoxin has been used as tool to investigate the mechanisms underlying peripheral neuroregeneration. Indeed this neurotoxin induces an acute, specific, localized and fully reversible damage of the presynaptic nerve terminal, and its action mimics the cascade of events that leads to nerve terminal degeneration in injured patients and in many neurodegenerative conditions. Here we provide evidence of an early release by degenerating neurons of adenosine triphosphate as alarm messenger, that contributes to the activation of a series of intracellular pathways within Schwann cells that are crucial for nerve regeneration: Ca2+, cAMP, ERK1/2, and CREB. These results contribute to define the cross-talk taking place among degenerating nerve terminals and PSCs, involved in the functional recovery of the NMJ. PMID:27242443

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

    PubMed Central

    Samara, Chrysanthi; Poirot, Olivier; Domènech-Estévez, Enric; Chrast, Roman

    2013-01-01

    The integrity and function of neurons depend on their continuous interactions with glial cells. In the peripheral nervous system glial functions are exerted by Schwann cells (SCs). SCs sense synaptic and extrasynaptic manifestations of action potential propagation and adapt their physiology to support neuronal activity. We review here existing literature data on extrasynaptic bidirectional axon-SC communication, focusing particularly on neuronal activity implications. To shed light on underlying mechanisms, we conduct a thorough analysis of microarray data from SC-rich mouse sciatic nerve at different developmental stages and in neuropathic models. We identify molecules that are potentially involved in SC detection of neuronal activity signals inducing subsequent glial responses. We further suggest that alterations in the activity-dependent axon-SC crosstalk impact on peripheral neuropathies. Together with previously reported data, these observations open new perspectives for deciphering glial mechanisms of neuronal function support. PMID:24324401

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

    PubMed Central

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

    2013-01-01

    CA3 pyramidal neurons are important for memory formation and pattern completion in the hippocampal network. It is generally thought that proximal synapses from the mossy fibers activate these neurons most efficiently, whereas distal inputs from the perforant path have a weaker modulatory influence. We used confocally targeted patch-clamp recording from dendrites and axons to map the activation of rat CA3 pyramidal neurons at the subcellular level. Our results reveal two distinct dendritic domains. In the proximal domain, action potentials initiated in the axon backpropagate actively with large amplitude and fast time course. In the distal domain, Na+ channel–mediated dendritic spikes are efficiently initiated by waveforms mimicking synaptic events. CA3 pyramidal neuron dendrites showed a high Na+-to-K+ conductance density ratio, providing ideal conditions for active backpropagation and dendritic spike initiation. Dendritic spikes may enhance the computational power of CA3 pyramidal neurons in the hippocampal network. PMID:22388958

  15. Demonstration of motor imagery movement and phantom movement-related neuronal activity in human thalamus.

    PubMed

    Anderson, William S; Weiss, Nirit; Lawson, Herman Christopher; Ohara, Shinji; Rowland, Lance; Lenz, Frederick A

    2011-01-26

    Functional imaging studies show that motor imagery activates multiple structures in the human forebrain. We now show that phantom movements in an amputee and imagined movements in intact individuals elicit responses from neurons in several human thalamic nuclei. These include the somatic sensory nucleus receiving input from the periphery (ventral caudal), and the motor nuclei receiving input from the cerebellum [ventral intermediate (Vim)] and the basal ganglia [ventral oral posterior (Vop)]. Seven neurons in the amputee showed phantom movement-related activity (three Vim, two Vop, and two ventral caudal). In addition, seven neurons in a group of three controls showed motor imagery-related activity (four Vim and three Vop). These studies were performed during single neuron recording sessions in patients undergoing therapeutic treatment of phantom pain, tremor, and chronic pain conditions by thalamic stimulation. The activity of neurons in these sensory and motor nuclei, respectively, may encode the expected sensory consequences and the dynamics of planned movements.

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

    PubMed

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

    2015-11-03

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

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

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  18. Deficient Rab11 activity underlies glucose hypometabolism in primary neurons of Huntington's disease mice

    SciTech Connect

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

    2012-05-18

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

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

    SciTech Connect

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

    2013-04-19

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

  20. Requirement of calcium-activated chloride channels in the activation of mouse vomeronasal neurons

    PubMed Central

    Kim, SangSeong; Ma, Limei; Yu, C. Ron

    2011-01-01

    In terrestrial vertebrates, the vomeronasal organ (VNO) detects and transduces pheromone signals. VNO activation is thought to be mediated by the transient receptor potential C2 (TRPC2) channel. The aberrant behavioural phenotypes observed in TRPC2−/− mice are generally attributed to the lost VNO function. Recently, calcium-activated chloride channels have been shown to contribute to VNO activation. Here we show that CACCs can be activated in VNO slice preparations from the TRPC2−/− mice and this activation is blocked by pharmacological agents that inhibit intracellular Ca2+ release. Urine-evoked Cl− current is sufficient to drive spiking changes in VNO neurons from both wild-type (WT) and TRPC2−/− mice. Moreover, blocking Cl− conductance essentially abolishes VNO activation in WT neurons. These results suggest a TRPC2-independent signalling pathway in the VNO and the requirement of calcium-activated chloride channels currents to mediate pheromone activation. Our data further suggest that TRPC2−/− mice retain partial VNO function. PMID:21694713

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

    ERIC Educational Resources Information Center

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

    2011-01-01

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

  2. Extracellular microRNAs activate nociceptor neurons to elicit pain via TLR7 and TRPA1.

    PubMed

    Park, Chul-Kyu; Xu, Zhen-Zhong; Berta, Temugin; Han, Qingjian; Chen, Gang; Liu, Xing-Jun; Ji, Ru-Rong

    2014-04-02

    Intracellular microRNAs (miRNAs) are key regulators of gene expression. The role of extracellular miRNAs in neuronal activation and sensory behaviors are unknown. Here we report an unconventional role of extracellular miRNAs for rapid excitation of nociceptor neurons via toll-like receptor-7 (TLR7) and its coupling to TRPA1 ion channel. miRNA-let-7b induces rapid inward currents and action potentials in dorsal root ganglion (DRG) neurons. These responses require the GUUGUGU motif, only occur in neurons coexpressing TLR7 and TRPA1, and are abolished in mice lacking Tlr7 or Trpa1. Furthermore, let-7b induces TLR7/TRPA1-dependent single-channel activities in DRG neurons and HEK293 cells overexpressing TLR7/TRPA1. Intraplantar injection of let-7b elicits rapid spontaneous pain via TLR7 and TRPA1. Finally, let-7b can be released from DRG neurons by neuronal activation, and let-7b inhibitor reduces formalin-induced TRPA1 currents and spontaneous pain. Thus, secreted extracellular miRNAs may serve as novel pain mediators via activating TLR7/TRPA1 in nociceptor neurons.

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

    PubMed Central

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

    2016-01-01

    CALHM1 is a cell surface calcium channel expressed in cerebral neurons. CALHM1 function in the brain remains unknown, but recent results showed that neuronal CALHM1 controls intracellular calcium signaling and cell excitability, two mechanisms required for synaptic function. Here, we describe the generation of Calhm1 knockout (Calhm1−/−) mice and investigate CALHM1 role in neuronal and cognitive functions. Structural analysis revealed that Calhm1−/− brains had normal regional and cellular architecture, and showed no evidence of neuronal or synaptic loss, indicating that CALHM1 deficiency does not affect brain development or brain integrity in adulthood. However, Calhm1−/− mice showed a severe impairment in memory flexibility, assessed in the Morris water maze, and a significant disruption of long-term potentiation without alteration of long-term depression, measured in ex vivo hippocampal slices. Importantly, in primary neurons and hippocampal slices, CALHM1 activation facilitated the phosphorylation of NMDA and AMPA receptors by protein kinase A. Furthermore, neuronal CALHM1 activation potentiated the effect of glutamate on the expression of c-Fos and C/EBPβ, two immediate-early gene markers of neuronal activity. Thus, CALHM1 controls synaptic activity in cerebral neurons and is required for the flexible processing of memory in mice. These results shed light on CALHM1 physiology in the mammalian brain. PMID:27066908

  4. Circuits constructed from identified Aplysia neurons exhibit multiple patterns of persistent activity.

    PubMed Central

    Kleinfeld, D; Raccuia-Behling, F; Chiel, H J

    1990-01-01

    We have used identified neurons from the abdominal ganglion of the mollusc Aplysia to construct and analyze two circuits in vitro. Each of these circuits was capable of producing two patterns of persistent activity; that is, they had bistable output states. The output could be switched between the stable states by a brief, external input. One circuit consisted of cocultured L10 and left upper quadrant (LUQ) neurons that formed reciprocal, inhibitory connections. In one stable state L10 was active and the LUQ was quiescent, whereas in the other stable state L10 was quiescent and the LUQ was active. A second circuit consisted of co-cultured L7 and L12 neurons that formed reciprocal, excitatory connections. In this circuit, both cells were quiescent in one stable state and both cells fired continuously in the other state. Bistable output in both circuits resulted from the nonlinear firing characteristics of each neuron and the feedback between the two neurons. We explored how the stability of the neuronal output could be controlled by the background currents injected into each neuron. We observed a relatively well-defined range of currents for which bistability occurred, consistent with the values expected from the measured strengths of the connections and a simple model. Outside of the range, the output was stable in only a single state. These results suggest how stable patterns of output are produced by some in vivo circuits and how command neurons from higher neural centers may control the activity of these circuits. The criteria that guided us in forming our circuits in culture were derived from theoretical studies on the properties of certain neuronal network models (e.g., Hopfield, J. J. 1984. Proc. Natl. Acad. Sci. USA. 81:3088-3092). Our results show that circuits consisting of only two co-cultured neurons can exhibit bistable output states of the form hypothesized to occur in populations of neurons. Images FIGURE 3 PMID:2344460

  5. Ensemble Recording of Electrical Activity in Neurons Derived from P19 Embryonal Carcinoma Cells

    NASA Astrophysics Data System (ADS)

    Takayama, Yuzo; Saito, Atushi; Moriguchi, Hiroyuki; Kotani, Kiyoshi; Jimbo, Yasuhiko

    Regeneration of the central nervous system (CNS) is one of the most important research themes in neuroscience and neuroengineering. It is essential to replenish the lost neurons and to establish appropriate functional neuronal networks using pluripotent stem cells. Little is known, however, about the properties of stem cell-derived neuronal networks, particularly under the differentiation and development processes. In this work, we cultured P19 embryonal carcinoma cells on micro-electrode arrays (MEAs). P19 cells were differentiated into neurons by retinoic acid application and formed densely connected networks. Spontaneous electrical activity was extracellulary recorded through substrate electrodes and analyzed. Synchronized periodic bursts, which were the characteristic features in primary cultured CNS neurons, were observed. Pharmacological studies demonstrated that the glutamatergic excitatory synapses and the GABAergic inhibitory synapses were active in these P19-derived neuronal networks. The results suggested that MEA-based recording was useful for monitoring differentiation processes of stem cells. P19-derived neuronal networks had quite similar network properties to those of primary cultured neurons, and thus provide a novel model system to investigate stem cell-based neuronal regeneration.

  6. Differential activation of orexin neurons by antipsychotic drugs associated with weight gain.

    PubMed

    Fadel, Jim; Bubser, Michael; Deutch, Ariel Y

    2002-08-01

    Weight gain is one side effect of many antipsychotic drugs (APDs). A small number of lateral hypothalamic/perifornical area (LH/PFA) neurons express the orexins, peptides that are critically involved in body weight regulation and arousal. We examined the ability of APDs to activate orexin neurons, as reflected by induction of Fos. APDs with significant weight gain liability increased Fos expression in orexin neurons, but APDs with low or absent weight gain liability did not. The weight gain liability of APDs was correlated with the degree of Fos induction in orexin neurons of the lateral LH/PFA. In contrast, amphetamine, which causes weight loss, increased Fos expression in orexin neurons of the medial but not lateral LH/PFA. We compared the effects of amphetamine and clozapine, an APD with weight gain liability, on orexin neurons innervating the prefrontal cortex. Clozapine induced Fos in 75% of the orexin neurons that project to the cortex, but amphetamine induced Fos in less than a third of these cells. These data suggest that APD-induced weight gain is associated with activation of distinct orexin neurons and emphasize the presence of anatomically and functionally heterogeneous populations of orexin neurons.

  7. Activity-Dependent Neuronal Control of Gap-Junctional Communication in Astrocytes

    PubMed Central

    Rouach, Nathalie; Glowinski, Jacques; Giaume, Christian

    2000-01-01

    A typical feature of astrocytes is their high degree of intercellular communication through gap junction channels. Using different models of astrocyte cultures and astrocyte/neuron cocultures, we have demonstrated that neurons upregulate gap-junctional communication and the expression of connexin 43 (Cx43) in astrocytes. The propagation of intercellular calcium waves triggered in astrocytes by mechanical stimulation was also increased in cocultures. This facilitation depends on the age and number of neurons, indicating that the state of neuronal differentiation and neuron density constitute two crucial factors of this interaction. The effects of neurons on astrocytic communication and Cx43 expression were reversed completely after neurotoxic treatments. Moreover, the neuronal facilitation of glial coupling was suppressed, without change in Cx43 expression, after prolonged pharmacological treatments that prevented spontaneous synaptic activity. Altogether, these results demonstrate that neurons exert multiple and differential controls on astrocytic gap-junctional communication. Since astrocytes have been shown to facilitate synaptic efficacy, our findings suggest that neuronal and astrocytic networks interact actively through mutual setting of their respective modes of communication. PMID:10871289

  8. Dynamic synchronization of ongoing neuronal activity across spinal segments regulates sensory information flow

    PubMed Central

    Contreras-Hernández, E; Chávez, D; Rudomin, P

    2015-01-01

    Previous studies on the correlation between spontaneous cord dorsum potentials recorded in the lumbar spinal segments of anaesthetized cats suggested the operation of a population of dorsal horn neurones that modulates, in a differential manner, transmission along pathways mediating Ib non-reciprocal postsynaptic inhibition and pathways mediating primary afferent depolarization and presynaptic inhibition. In order to gain further insight into the possible neuronal mechanisms that underlie this process, we have measured changes in the correlation between the spontaneous activity of individual dorsal horn neurones and the cord dorsum potentials associated with intermittent activation of these inhibitory pathways. We found that high levels of neuronal synchronization within the dorsal horn are associated with states of incremented activity along the pathways mediating presynaptic inhibition relative to pathways mediating Ib postsynaptic inhibition. It is suggested that ongoing changes in the patterns of functional connectivity within a distributed ensemble of dorsal horn neurones play a relevant role in the state-dependent modulation of impulse transmission along inhibitory pathways, among them those involved in the central control of sensory information. This feature would allow the same neuronal network to be involved in different functional tasks. Key points We have examined, in the spinal cord of the anaesthetized cat, the relationship between ongoing correlated fluctuations of dorsal horn neuronal activity and state-dependent activation of inhibitory reflex pathways. We found that high levels of synchronization between the spontaneous activity of dorsal horn neurones occur in association with the preferential activation of spinal pathways leading to primary afferent depolarization and presynaptic inhibition relative to activation of pathways mediating Ib postsynaptic inhibition. It is suggested that changes in synchronization of ongoing activity within a

  9. Self-organization of synchronous activity propagation in neuronal networks driven by local excitation.

    PubMed

    Bayati, Mehdi; Valizadeh, Alireza; Abbassian, Abdolhossein; Cheng, Sen

    2015-01-01

    Many experimental and theoretical studies have suggested that the reliable propagation of synchronous neural activity is crucial for neural information processing. The propagation of synchronous firing activity in so-called synfire chains has been studied extensively in feed-forward networks of spiking neurons. However, it remains unclear how such neural activity could emerge in recurrent neuronal networks through synaptic plasticity. In this study, we investigate whether local excitation, i.e., neurons that fire at a higher frequency than the other, spontaneously active neurons in the network, can shape a network to allow for synchronous activity propagation. We use two-dimensional, locally connected and heterogeneous neuronal networks with spike-timing dependent plasticity (STDP). We find that, in our model, local excitation drives profound network changes within seconds. In the emergent network, neural activity propagates synchronously through the network. This activity originates from the site of the local excitation and propagates through the network. The synchronous activity propagation persists, even when the local excitation is removed, since it derives from the synaptic weight matrix. Importantly, once this connectivity is established it remains stable even in the presence of spontaneous activity. Our results suggest that synfire-chain-like activity can emerge in a relatively simple way in realistic neural networks by locally exciting the desired origin of the neuronal sequence.

  10. Improved Visualization of Neuronal Injury Following Glial Activation by Manganese Enhanced MRI

    PubMed Central

    Bade, Aditya N.; Zhou, Biyun; Epstein, Adrian A.; Gorantla, Santhi; Poluektova, Larisa Y.; Luo, Jiangtao; Gendelman, Howard E.; Boska, Michael D.; Liu, Yutong

    2013-01-01

    Research directed at anatomical, integrative and functional activities of the central nervous system (CNS) can be realized through bioimaging. A wealth of data now demonstrates the utility of magnetic resonance imaging (MRI) towards unraveling complex neural connectivity operative in health and disease. A means to improve MRI sensitivity is through contrast agents and notably manganese (Mn2+). The Mn2+ ions enter neurons through voltage-gated calcium channels and unlike other contrast agents such as gadolinium, iron oxide, iron platinum and imaging proteins, provide unique insights into brain physiology. Nonetheless, a critical question that remains is the brain target cells serving as sources for the signal of Mn2+ enhanced MRI (MEMRI). To this end, we investigated MEMRI’s abilities to detect glial (astrocyte and microglia) and neuronal activation signals following treatment with known inflammatory inducing agents. The idea is to distinguish between gliosis (glial activation) and neuronal injury for the MEMRI signal and as such use the agent as a marker for neural activity in inflammatory and degenerative disease. We now demonstrate that glial inflammation facilitates Mn2+ neuronal ion uptake. Glial Mn2+ content was not linked to its activation. MEMRI performed on mice injected intracranially with lipopolysaccharide was associated with increased neuronal activity. These results support the notion that MEMRI reflects neuronal excitotoxicity and impairment that can occur through a range of insults including neuroinflammation. We conclude that the MEMRI signal enhancement is induced by inflammation stimulating neuronal Mn2+ uptake. PMID:23729245

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

    PubMed

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

    2015-05-01

    Elevations in neuronal cholesterol have been associated with several degenerative diseases. An enhanced excitability and synchronous firing in surviving neurons are among the sequels of neuronal death in these diseases and also in some epileptic syndromes. Here, we attempted to increase neuronal cholesterol levels, using a short hairpin RNA to suppress expression of the enzyme cytochrome P450 family 46, subfamily A, polypeptide 1 gene (CYP46A1). This protein hydroxylates cholesterol and so facilitates transmembrane extrusion. A short hairpin RNA CYP46A1construction coupled to the adeno-associated virus type 5 was injected focally and unilaterally into mouse hippocampus. It was selectively expressed first in neurons of the cornu ammonis (hippocampus) (CA)3a region. Cytoplasmic and membrane cholesterol increased, and the neuronal soma volume increased and then decreased before pyramidal cells died. As CA3a pyramidal cells died, interictal electroencephalographic (EEG) events occurred during exploration and non-rapid eye movement sleep. With time, neuronal death spread to involve pyramidal cells and interneurons of the CA1 region. CA1 neuronal death was correlated with a delayed local expression of phosphorylated tau. Astrocytes were activated throughout the hippocampus and microglial activation was specific to regions of neuronal death. CA1 neuronal death was correlated with distinct aberrant EEG activity. During exploratory behaviour and rapid eye movement sleep, EEG oscillations at 7-10 Hz (theta) could accelerate to 14-21 Hz (beta) waves. They were accompanied by low-amplitude, high-frequency oscillations of peak power at ~300 Hz and a range of 250-350 Hz. Although episodes of EEG acceleration were not correlated with changes in exploratory behaviour, they were followed in some animals by structured seizure-like discharges. These data strengthen links between increased cholesterol, neuronal sclerosis and epileptic behaviour.

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

    PubMed Central

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

    2015-01-01

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

  13. Large-conductance calcium-activated potassium current modulates excitability in isolated canine intracardiac neurons

    PubMed Central

    Pérez, Guillermo J.; Desai, Mayurika; Anderson, Seth

    2013-01-01

    We studied principal neurons from canine intracardiac (IC) ganglia to determine whether large-conductance calcium-activated potassium (BK) channels play a role in their excitability. We performed whole cell recordings in voltage- and current-clamp modes to measure ion currents and changes in membrane potential from isolated canine IC neurons. Whole cell currents from these neurons showed fast- and slow-activated outward components. Both current components decreased in the absence of calcium and following 1–2 mM tetraethylammonium (TEA) or paxilline. These results suggest that BK channels underlie these current components. Single-channel analysis showed that BK channels from IC neurons do not inactivate in a time-dependent manner, suggesting that the dynamic of the decay of the fast current component is akin to that of intracellular calcium. Immunohistochemical studies showed that BK channels and type 2 ryanodine receptors are coexpressed in IC principal neurons. We tested whether BK current activation in these neurons occurred via a calcium-induced calcium release mechanism. We found that the outward currents of these neurons were not affected by the calcium depletion of intracellular stores with 10 mM caffeine and 10 μM cyclopiazonic acid. Thus, in canine intracardiac neurons, BK currents are directly activated by calcium influx. Membrane potential changes elicited by long (400 ms) current injections showed a tonic firing response that was decreased by TEA or paxilline. These data strongly suggest that the BK current present in canine intracardiac neurons regulates action potential activity and could increase these neurons excitability. PMID:23195072

  14. Activation of hypothalamic gono-like neurons in female rats during estrus☆

    PubMed Central

    Ren, Xiaoxuan; Wang, Shaojun; Rong, Peijing; Zhu, Bing

    2012-01-01

    In mammals, gonadal function is controlled by the activity of hypothalamic gonadotropin-releasing hormone neurons, which control the secretion of adenohypophyseal and gonadal hormones. However, there are a number of unanswered questions in relation to gonadal function. It is currently unknown how erotogenic stimulation of the genitals influences the subpopulation of hypothalamic medial preoptic area neurons, antidromically identified as projecting to the median eminence at different periods of the estrous cycle. Additionally, the distinctiveness of hypothalamic medial preoptic area neurons, with respect to methods of feedback control by exogenous hormones, is also unknown. In this study, spontaneous discharges from individual neurons encountered within the medial preoptic area, gono-like neurons, were recorded extracellularly using glass microelectrodes. To confirm the cellular and histochemical properties of the recording units, antidromic stimulation was performed using a side-by-side bipolar stimulating electrode placed into the median eminence, alongside microiontophoretic injections of the conventional tracer, horseradish peroxidase. In addition, further immunohistochemical analyses were performed. Results showed that elevated gono-neuron activity was accompanied by increased background activity and greater responses to erotogenic stimuli during estrus. Application of clitoral traction stimulation resulted in increased activation of the gono-like neurons. This neuronal activity was noticeably inhibited by β-estradiol administration. Immunohistochemical analyses revealed the presence of gonadotropin-releasing hormone-reactive protein in hypothalamic cells in which electrophysiological recordings were taken. Thus, medial preoptic area neurons represent the subset of hypothalamic gonadotropin-releasing hormone neurons described from brain slices in vitro, and might serve as a useful physiological model to form the basis of future in vivo studies. PMID:25337091

  15. Daily variation in the electrophysiological activity of mouse medial habenula neurones

    PubMed Central

    Sakhi, Kanwal; Belle, Mino D C; Gossan, Nicole; Delagrange, Philippe; Piggins, Hugh D

    2014-01-01

    AbstractIntrinsic daily or circadian rhythms arise through the outputs of the master circadian clock in the brain's suprachiasmatic nuclei (SCN) as well as circadian oscillators in other brain sites and peripheral tissues. SCN neurones contain an intracellular molecular clock that drives these neurones to exhibit pronounced day–night differences in their electrical properties. The epithalamic medial habenula (MHb) expresses clock genes, but little is known about the bioelectric properties of mouse MHb neurones and their potential circadian characteristics. Therefore, in this study we used a brain slice preparation containing the MHb to determine the basic electrical properties of mouse MHb neurones with whole-cell patch clamp electrophysiology, and investigated whether these vary across the day–night cycle. MHb neurones (n = 230) showed heterogeneity in electrophysiological state, ranging from highly depolarised cells (∼ −25 to −30 mV) that are silent with no membrane activity or display depolarised low-amplitude membrane oscillations, to neurones that were moderately hyperpolarised (∼40 mV) and spontaneously discharging action potentials. These electrical states were largely intrinsically regulated and were influenced by the activation of small-conductance calcium-activated potassium channels. When considered as one population, MHb neurones showed significant circadian variation in their spontaneous firing rate and resting membrane potential. However, in recordings of MHb neurones from mice lacking the core molecular circadian clock, these temporal differences in MHb activity were absent, indicating that circadian clock signals actively regulate the timing of MHb neuronal states. These observations add to the extracellularly recorded rhythms seen in other brain areas and establish that circadian mechanisms can influence the membrane properties of neurones in extra-SCN sites. Collectively, the results of this study indicate that the MHb may

  16. Importance of being Nernst: Synaptic activity and functional relevance in stem cell-derived neurons

    PubMed Central

    Bradford, Aaron B; McNutt, Patrick M

    2015-01-01

    Functional synaptogenesis and network emergence are signature endpoints of neurogenesis. These behaviors provide higher-order confirmation that biochemical and cellular processes necessary for neurotransmitter release, post-synaptic detection and network propagation of neuronal activity have been properly expressed and coordinated among cells. The development of synaptic neurotransmission can therefore be considered a defining property of neurons. Although dissociated primary neuron cultures readily form functioning synapses and network behaviors in vitro, continuously cultured neurogenic cell lines have historically failed to meet these criteria. Therefore, in vitro-derived neuron models that develop synaptic transmission are critically needed for a wide array of studies, including molecular neuroscience, developmental neurogenesis, disease research and neurotoxicology. Over the last decade, neurons derived from various stem cell lines have shown varying ability to develop into functionally mature neurons. In this review, we will discuss the neurogenic potential of various stem cells populations, addressing strengths and weaknesses of each, with particular attention to the emergence of functional behaviors. We will propose methods to functionally characterize new stem cell-derived neuron (SCN) platforms to improve their reliability as physiological relevant models. Finally, we will review how synaptically active SCNs can be applied to accelerate research in a variety of areas. Ultimately, emphasizing the critical importance of synaptic activity and network responses as a marker of neuronal maturation is anticipated to result in in vitro findings that better translate to efficacious clinical treatments. PMID:26240679

  17. Histamine excites rat lateral vestibular nuclear neurons through activation of post-synaptic H2 receptors.

    PubMed

    Zhang, Jun; Han, Xiao-Hu; Li, Hong-Zhao; Zhu, Jing-Ning; Wang, Jian-Jun

    2008-12-19

    Through whole-cell patch recordings in brainstem slices, the effects of histamine on neuronal activity of the lateral vestibular nucleus (LVN) were investigated. Bath application of histamine elicited a concentration-dependent excitation of both spontaneous firing (n=19) and silent (n=7) LVN neurons. Moreover, histamine induced a stable inward current in the LVN neurons (n=5) and the histamine-induced depolarization of membrane potential persisted in the presence of tetrodotoxin (n=4), indicating a direct post-synaptic effect of the histamine on the LVN neurons. Selective histamine H2 receptor antagonist ranitidine effectively blocked the histamine-evoked excitatory responses on the LVN neurons (n=4), but selective histamine H1 receptor antagonist triprolidine did not (n=4). In addition, selective histamine H2 receptor agonist dimaprit (n=3) rather than 2-pyridylethylamine (n=4), a selective histamine H1 receptor agonist, mimicked the excitatory action of histamine on LVN neurons. The results demonstrate that histamine excites the LVN neurons via post-synaptic histamine H2 receptors and suggest that the central histaminergic projection arising from the hypothalamus may modulate LVN neurons activity and actively influence the vestibular reflexes and functions.

  18. Activation of Oral Trigeminal Neurons by Fatty Acids is Dependent upon Intracellular Calcium

    PubMed Central

    Yu, Tian; Shah, Bhavik P.; Hansen, Dane R.; Park-York, MieJung; Gilbertson, Timothy A.

    2012-01-01

    The chemoreception of dietary fat in the oral cavity has largely been attributed to activation of the somatosensory system that conveys the textural properties of fat. However, the ability of fatty acids, which are believed to represent the proximate stimulus for fat taste, to stimulate rat trigeminal neurons has remained unexplored. Here, we found that several free fatty acids are capable of activating trigeminal neurons with different kinetics. Further, a polyunsaturated fatty acid, linoleic acid (LA), activates trigeminal neurons by increasing intracellular calcium concentration and generating depolarizing receptor potentials. Ion substitution and pharmacological approaches reveal that intracellular calcium store depletion is crucial for LA-induced signaling in a subset of trigeminal neurons. Using pseudorabies virus (PrV) as a live cell tracer, we identified a subset of lingual nerve-innervated trigeminal neurons that respond to different subsets of fatty acids. Quantitative real-time PCR of several transient receptor potential (TRP) channel markers in individual neurons validated that PrV labeled a subset but not the entire population of lingual-innervated trigeminal neurons. We further confirmed that the LA-induced intracellular calcium rise is exclusively coming from the release of calcium stores from the endoplasmic reticulum in this subset of lingual nerve-innervated trigeminal neurons. PMID:22644615

  19. Improved expression of halorhodopsin for light-induced silencing of neuronal activity.

    PubMed

    Zhao, Shengli; Cunha, Catarina; Zhang, Feng; Liu, Qun; Gloss, Bernd; Deisseroth, Karl; Augustine, George J; Feng, Guoping

    2008-08-01

    The ability to control and manipulate neuronal activity within an intact mammalian brain is of key importance for mapping functional connectivity and for dissecting the neural circuitry underlying behaviors. We have previously generated transgenic mice that express channelrhodopsin-2 for light-induced activation of neurons and mapping of neural circuits. Here we describe transgenic mice that express halorhodopsin (NpHR), a light-driven chloride pump that can be used to silence neuronal activity via light. Using the Thy-1 promoter to target NpHR expression to neurons, we found that neurons in these mice expressed high levels of NpHR-YFP and that illumination of cortical pyramidal neurons expressing NpHR-YFP led to rapid, reversible photoinhibition of action potential firing in these cells. However, NpHR-YFP expression led to the formation of numerous intracellular blebs, which may disrupt neuronal function. Labeling of various subcellular markers indicated that the blebs arise from retention of NpHR-YFP in the endoplasmic reticulum. By improving the signal peptide sequence and adding an ER export signal to NpHR-YFP, we eliminated the formation of blebs and dramatically increased the membrane expression of NpHR-YFP. Thus, the improved version of NpHR should serve as an excellent tool for neuronal silencing in vitro and in vivo.

  20. Decompensated hemorrhage activates serotonergic neurons in the subependymal parapyramidal region of the rat medulla.

    PubMed

    Pelaez, Nicole M; Schreihofer, Ann M; Guyenet, Patrice G

    2002-09-01

    According to prior evidence opioid and serotonin release by lower brain stem neurons may contribute to hemorrhage-induced sympathoinhibition (HISI). Here we seek direct evidence for the activation of opioidergic, GABAergic, or serotonergic neurons by severe hemorrhage in the medulla oblongata. Blood was withdrawn from awake rats (40-50% total volume) causing hypotension and profound initial bradycardia. Other rats received the vasodilator hydralazine, causing tachycardia and hypotension. Neuronal activation was gauged by the presence of Fos-immunoreactive (ir) nuclei after 2 h. Serotonergic, enkephalinergic, and GABAergic neurons were identified by the presence of a diagnostic enzyme or mRNA. Hemorrhaged rats had 30% fewer non-GABAergic Fos-ir neurons in the rostral ventrolateral medulla (RVLM) than hydralazine-treated rats, but they had six times more Fos-ir neurons within the subependymal parapyramidal nucleus (SEPPN). Fos-labeled SEPPN neurons were serotonergic (40-60%), GABAergic (31%), enkephalinergic (15%), or had mixed phenotypes. The data suggest that a reduced sympathoexcitatory drive from RVLM may contribute to HISI. SEPPN neuronal activation may also contribute to HISI or could mediate defensive thermoregulatory mechanisms triggered by hemorrhage-induced hypothermia.

  1. Matrix stiffness modulates formation and activity of neuronal networks of controlled architectures.

    PubMed

    Lantoine, Joséphine; Grevesse, Thomas; Villers, Agnès; Delhaye, Geoffrey; Mestdagh, Camille; Versaevel, Marie; Mohammed, Danahe; Bruyère, Céline; Alaimo, Laura; Lacour, Stéphanie P; Ris, Laurence; Gabriele, Sylvain

    2016-05-01

    The ability to construct easily in vitro networks of primary neurons organized with imposed topologies is required for neural tissue engineering as well as for the development of neuronal interfaces with desirable characteristics. However, accumulating evidence suggests that the mechanical properties of the culture matrix can modulate important neuronal functions such as growth, extension, branching and activity. Here we designed robust and reproducible laminin-polylysine grid micropatterns on cell culture substrates that have similar biochemical properties but a 100-fold difference in Young's modulus to investigate the role of the matrix rigidity on the formation and activity of cortical neuronal networks. We found that cell bodies of primary cortical neurons gradually accumulate in circular islands, whereas axonal extensions spread on linear tracks to connect circular islands. Our findings indicate that migration of cortical neurons is enhanced on soft substrates, leading to a faster formation of neuronal networks. Furthermore, the pre-synaptic density was two times higher on stiff substrates and consistently the number of action potentials and miniature synaptic currents was enhanced on stiff substrates. Taken together, our results provide compelling evidence to indicate that matrix stiffness is a key parameter to modulate the growth dynamics, synaptic density and electrophysiological activity of cortical neuronal networks, thus providing useful information on scaffold design for neural tissue engineering.

  2. Holographic optogenetic stimulation of patterned neuronal activity for vision restoration.

    PubMed

    Reutsky-Gefen, Inna; Golan, Lior; Farah, Nairouz; Schejter, Adi; Tsur, Limor; Brosh, Inbar; Shoham, Shy

    2013-01-01

    When natural photoreception is disrupted, as in outer-retinal degenerative diseases, artificial stimulation of surviving nerve cells offers a potential strategy for bypassing compromised neural circuits. Recently, light-sensitive proteins that photosensitize quiescent neurons have generated unprecedented opportunities for optogenetic neuronal control, inspiring early development of optical retinal prostheses. Selectively exciting large neural populations are essential for eliciting meaningful perceptions in the brain. Here we provide the first demonstration of holographic photo-stimulation strategies for bionic vision restoration. In blind retinas, we demonstrate reliable holographically patterned optogenetic stimulation of retinal ganglion cells with millisecond temporal precision and cellular resolution. Holographic excitation strategies could enable flexible control over distributed neuronal circuits, potentially paving the way towards high-acuity vision restoration devices and additional medical and scientific neuro-photonics applications.

  3. Active Percolation Analysis of Pyramidal Neurons of Somatosensory Cortex:

    NASA Astrophysics Data System (ADS)

    Costa, Luciano Da Fontoura; Barbosa, Marconi Soares; Schierwagen, Andreas; Alpár, Alán; Gärtner, Ulrich; Arendt, Thomas

    This article describes the investigation of morphological variations among two sets of neuronal cells, namely a control group of wild type mouse cells and a group of cells of a transgenic line. Special attention is given to singular points in the neuronal structure, namely the branching points and extremities of the dendritic processes. The characterization of the spatial distribution of such points is obtained by using a recently reported morphological technique based on forced percolation and window-size compensation, which is particularly suited to the analysis of scattered points, presenting several coexisting densities. Different dispersions were identified in our statistical analysis, suggesting that the transgenic line of neurons is characterized by a more pronounced morphological variation. A classification scheme based on a canonical discriminant function was also considered in order to identify the morphological differences.

  4. Energy dependence on the electric activities of a neuron

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    A nonlinear circuit can be designed by using inductor, resistor, capacitor and other electric devices, and the electromagnetic field energy can be released from the circuit in the oscillating state. The generation of spikes or bursting states in neurons could be energetically a costly process. Based on the Helmholtz’s theorem, a Hamilton energy function is defined to detect the energy shift induced by transition of electric modes in a Hindmarsh-Rose neuron. It is found that the energy storage is dependent on the external forcing, and energy release is associated with the electric mode. As a result, the bursting state and chaotic state could be helpful to release the energy in the neuron quickly. Project supported by the National Natural Science Foundation of China (Grant Nos. 11372122 and 11365014).

  5. The calcium-activated chloride channel anoctamin 1 acts as a heat sensor in nociceptive neurons.

    PubMed

    Cho, Hawon; Yang, Young Duk; Lee, Jesun; Lee, Byeongjoon; Kim, Tahnbee; Jang, Yongwoo; Back, Seung Keun; Na, Heung Sik; Harfe, Brian D; Wang, Fan; Raouf, Ramin; Wood, John N; Oh, Uhtaek

    2012-05-27

    Nociceptors are a subset of small primary afferent neurons that respond to noxious chemical, thermal and mechanical stimuli. Ion channels in nociceptors respond differently to noxious stimuli and generate electrical signals in different ways. Anoctamin 1 (ANO1 also known as TMEM16A) is a Ca(2+)-activated chloride channel that is essential for numerous physiological functions. We found that ANO1 was activated by temperatures over 44 °C with steep heat sensitivity. ANO1 was expressed in small sensory neurons and was highly colocalized with nociceptor markers, which suggests that it may be involved in nociception. Application of heat ramps to dorsal root ganglion (DRG) neurons elicited robust ANO1-dependent depolarization. Furthermore, knockdown or deletion of ANO1 in DRG neurons substantially reduced nociceptive behavior in thermal pain models. These results indicate that ANO1 is a heat sensor that detects nociceptive thermal stimuli in sensory neurons and possibly mediates nociception.

  6. Spatial Frequency Components of Images Modulate Neuronal Activity in Monkey Amygdala.

    PubMed

    Montes-Lourido, Pilar; Bermudez, M A; Romero, M C; Vicente, A F; Gonzalez, F

    2016-04-01

    Processing the spatial frequency components of an image is a crucial feature for visual perception, especially in recognition of faces. Here, we study the correlation between spatial frequency components of images of faces and neuronal activity in monkey amygdala while performing a visual recognition task. The frequency components of the images were analyzed using a fast Fourier transform for 40 spatial frequency ranges. We recorded 65 neurons showing statistically significant responses to at least one of the images used as a stimulus. A total of 37 of these neurons (n = 37) showed significant responses to at least three images, and in eight of them (8/37, 22%), we found a statistically significant correlation between neuron response and the modulus amplitude of at least one frequency range present in the images. Our results indicate that high spatial frequency and low spatial frequency components of images influence the activity of amygdala neurons.

  7. Ran-dependent TPX2 activation promotes acentrosomal microtubule nucleation in neurons

    PubMed Central

    Chen, Wen-Shin; Chen, Yi-Ju; Huang, Yung-An; Hsieh, Bing-Yuan; Chiu, Ho-Chieh; Kao, Pei-Ying; Chao, Chih-Yuan; Hwang, Eric

    2017-01-01

    The microtubule (MT) cytoskeleton is essential for the formation of morphologically appropriate neurons. The existence of the acentrosomal MT organizing center in neurons has been proposed but its identity remained elusive. Here we provide evidence showing that TPX2 is an important component of this acentrosomal MT organizing center. First, neurite elongation is compromised in TPX2-depleted neurons. In addition, TPX2 localizes to the centrosome and along the neurite shaft bound to MTs. Depleting TPX2 decreases MT formation frequency specifically at the tip and the base of the neurite, and these correlate precisely with the regions where active GTP-bound Ran proteins are enriched. Furthermore, overexpressing the downstream effector of Ran, importin, compromises MT formation and neuronal morphogenesis. Finally, applying a Ran-importin signaling interfering compound phenocopies the effect of TPX2 depletion on MT dynamics. Together, these data suggest a model in which Ran-dependent TPX2 activation promotes acentrosomal MT nucleation in neurons. PMID:28205572

  8. Sleep-active neuron specification and sleep induction require FLP-11 neuropeptides to systemically induce sleep.

    PubMed

    Turek, Michal; Besseling, Judith; Spies, Jan-Philipp; König, Sabine; Bringmann, Henrik

    2016-03-07

    Sleep is an essential behavioral state. It is induced by conserved sleep-active neurons that express GABA. However, little is known about how sleep neuron function is determined and how sleep neurons change physiology and behavior systemically. Here, we investigated sleep in Caenorhabditis elegans, which is induced by the single sleep-active neuron RIS. We found that the transcription factor LIM-6, which specifies GABAergic function, in parallel determines sleep neuron function through the expression of APTF-1, which specifies the expression of FLP-11 neuropeptides. Surprisingly FLP-11, and not GABA, is the major component that determines the sleep-promoting function of RIS. FLP-11 is constantly expressed in RIS. At sleep onset RIS depolarizes and releases FLP-11 to induce a systemic sleep state.

  9. Sleep-active neuron specification and sleep induction require FLP-11 neuropeptides to systemically induce sleep

    PubMed Central

    Turek, Michal; Besseling, Judith; Spies, Jan-Philipp; König, Sabine; Bringmann, Henrik

    2016-01-01

    Sleep is an essential behavioral state. It is induced by conserved sleep-active neurons that express GABA. However, little is known about how sleep neuron function is determined and how sleep neurons change physiology and behavior systemically. Here, we investigated sleep in Caenorhabditis elegans, which is induced by the single sleep-active neuron RIS. We found that the transcription factor LIM-6, which specifies GABAergic function, in parallel determines sleep neuron function through the expression of APTF-1, which specifies the expression of FLP-11 neuropeptides. Surprisingly FLP-11, and not GABA, is the major component that determines the sleep-promoting function of RIS. FLP-11 is constantly expressed in RIS. At sleep onset RIS depolarizes and releases FLP-11 to induce a systemic sleep state. DOI: http://dx.doi.org/10.7554/eLife.12499.001 PMID:26949257

  10. Contribution of Drosophila TRPA1-expressing neurons to circadian locomotor activity patterns.

    PubMed

    Lee, Youngseok

    2013-01-01

    In both vertebrates and invertebrates, Transient Receptor Potential (TRP) channels are expressed in sensory neurons and mediate environmental stimuli such as light, sound, temperature, and taste. Some of these channels, however, are expressed only in the brain and their functions remain incompletely understood. Using the GAL4/UAS binary system with a line in which the GAL4 had been knocked into the trpA1 locus in Drosophila, we recently reported new insights into TRPA1 localization and function, including its expression in approximately 15% of all circadian neurons. TRPA1 is expressed in lateral posterior neurons (LPNs), which are known to be highly sensitive to entrainment by temperature cycles. Here, I used the bacterial sodium channel, NaChBac, to examine the effects of altering the electrical properties of trpA1 neurons on circadian rhythms. My results indicate that circadian activity of the flies in the morning, daytime, and evening was affected in a temperature-dependent manner following TRPA1 neuronal activation. Remarkably, TRPA1 neuron activation in flies kept at 18°C impacted the morning peak of circadian activity even though TRPA1 is not expressed in morning cells. Taken together, these results suggest that the activation of TRPA1-expressing neurons may differentially coordinate light/dark circadian entrainment, depending on the temperature.

  11. Disruption of dopamine neuron activity pattern regulation through selective expression of a human KCNN3 mutation.

    PubMed

    Soden, Marta E; Jones, Graham L; Sanford, Christina A; Chung, Amanda S; Güler, Ali D; Chavkin, Charles; Luján, Rafael; Zweifel, Larry S

    2013-11-20

    The calcium-activated small conductance potassium channel SK3 plays an essential role in the regulation of dopamine neuron activity patterns. Here we demonstrate that expression of a human disease-related SK3 mutation (hSK3Δ) in dopamine neurons of mice disrupts the balance between tonic and phasic dopamine neuron activity. Expression of hSK3Δ suppressed endogenous SK currents, reducing coupling between SK channels and NMDA receptors (NMDARs) and increasing permissiveness for burst firing. Consistent with enhanced excitability of dopamine neurons, hSK3Δ increased evoked calcium signals in dopamine neurons in vivo and potentiated evoked dopamine release. Specific expression of hSK3Δ led to deficits in attention and sensory gating and heightened sensitivity to a psychomimetic drug. Sensory-motor alterations and psychomimetic sensitivity were recapitulated in a mouse model of transient, reversible dopamine neuron activation. These results demonstrate the cell-autonomous effects of a human ion channel mutation on dopamine neuron physiology and the impact of activity pattern disruption on behavior.

  12. Neuronal production of lipocalin-2 as a help-me signal for glial activation

    PubMed Central

    Xing, Changhong; Wang, Xiaoshu; Cheng, Chongjie; Montaner, Joan; Mandeville, Emiri; Leung, Wendy; van Leyen, Klaus; Lok, Josephine; Wang, Xiaoying; Lo, Eng H.

    2014-01-01

    Background and purpose We explored the hypothesis that injured neurons release lipocalin-2 as a help-me signal. Methods In vivo lipocalin-2 responses were assessed in rat focal cerebral ischemia and human stroke brain samples using a combination of ELISA and immunostaining. In vitro, microglia and astrocytes were exposed to lipocalin-2 and various markers and assays of glial activation were quantified. Functional relevance of neuron-to-glia lipocalin-2 signaling was examined by transferring conditioned media from lipocalin-2-activated microglia and astrocytes onto neurons to see whether activated glia could protect neurons against oxygen-glucose deprivation and promote neuroplasticity. Results In human stroke samples and rat cerebral ischemia, neuronal expression of lipocalin-2 was significantly increased. In primary cell cultures, exposing microglia and astrocytes to lipocalin-2 resulted in glial activation. In microglia, lipocalin-2 converted resting ramified shapes into a long-rod morphology with reduced branching, increased interleukin-10 release, and enhanced phagocytosis. In astrocytes, lipocalin-2 upregulated GFAP, BDNF and thrombospondin-1. Conditioned media from lipocalin-2-treated astrocytes upregulated synaptotagmin, and conditioned media from lipocalin-2-treated microglia upregulated synaptophysin and PSD95 and protected neurons against oxygen-glucose deprivation. Conclusions These findings provide proof-of-concept that lipocalin-2 is released by injured neurons as a “help-me” distress signal that activates microglia and astrocytes into potentially pro-recovery phenotypes. PMID:24916903

  13. Sleep- and wake-dependent changes in neuronal activity and reactivity demonstrated in fly neurons using in vivo calcium imaging.

    PubMed

    Bushey, Daniel; Tononi, Giulio; Cirelli, Chiara

    2015-04-14

    Sleep in Drosophila shares many features with mammalian sleep, but it remains unknown whether spontaneous and evoked activity of individual neurons change with the sleep/wake cycle in flies as they do in mammals. Here we used calcium imaging to assess how the Kenyon cells in the fly mushroom bodies change their activity and reactivity to stimuli during sleep, wake, and after short or long sleep deprivation. As before, sleep was defined as a period of immobility of >5 min associated with a reduced behavioral response to a stimulus. We found that calcium levels in Kenyon cells decline when flies fall asleep and increase when they wake up. Moreover, calcium transients in response to two different stimuli are larger in awake flies than in sleeping flies. The activity of Kenyon cells is also affected by sleep/wake history: in awake flies, more cells are spontaneously active and responding to stimuli if the last several hours (5-8 h) before imaging were spent awake rather than asleep. By contrast, long wake (≥29 h) reduces both baseline and evoked neural activity and decreases the ability of neurons to respond consistently to the same repeated stimulus. The latter finding may underlie some of the negative effects of sleep deprivation on cognitive performance and is consistent with the occurrence of local sleep during wake as described in behaving rats. Thus, calcium imaging uncovers new similarities between fly and mammalian sleep: fly neurons are more active and reactive in wake than in sleep, and their activity tracks sleep/wake history.

  14. Spinal 5-HT(3) receptor activation induces behavioral hypersensitivity via a neuronal-glial-neuronal signaling cascade.

    PubMed

    Gu, Ming; Miyoshi, Kan; Dubner, Ronald; Guo, Wei; Zou, Shiping; Ren, Ke; Noguchi, Koichi; Wei, Feng

    2011-09-07

    Recent studies indicate that the descending serotonin (5-HT) system from the rostral ventromedial medulla (RVM) in the brainstem and the 5-HT(3) receptor subtype in the spinal dorsal horn are involved in enhanced descending pain facilitation after tissue and nerve injury. However, the mechanisms underlying the activation of the 5-HT(3) receptor and its contribution to facilitation of pain remain unclear. In the present study, activation of spinal 5-HT(3) receptor by intrathecal injection of a selective 5-HT(3) receptor agonist, SR57227, induced spinal glial hyperactivity, neuronal hyperexcitability, and pain hypersensitivity in rats. We found that there was neuron-to-microglia signaling via chemokine fractalkine, microglia to astrocyte signaling via the cytokine IL-18, astrocyte to neuronal signaling by IL-1β, and enhanced activation of GluN (NMDA) receptors in the spinal dorsal horn. In addition, exogenous brain-derived neurotrophic factor-induced descending pain facilitation was accompanied by upregulation of CD11b and GFAP expression in the spinal dorsal horn after microinjection in the RVM, and these events were significantly prevented by functional blockade of spinal 5-HT(3) receptors. Enhanced expression of spinal CD11b and GFAP after hindpaw inflammation was also attenuated by molecular depletion of the descending 5-HT system by intra-RVM Tph-2 shRNA interference. Thus, these findings offer new insights into the cellular and molecular mechanisms at the spinal level responsible for descending 5-HT-mediated pain facilitation during the development of persistent pain after tissue and nerve injury. New pain therapies should focus on prime targets of descending facilitation-induced glial involvement, and in particular the blocking of intercellular signaling transduction between neuron and glia.

  15. Spinal 5-HT3 receptor activation induces behavioral hypersensitivity via a neuronal-glial-neuronal signaling cascade

    PubMed Central

    Gu, Ming; Miyoshi, Kan; Dubner, Ronald; Guo, Wei; Zou, Shiping; Ren, Ke; Noguchi, Koichi; Wei, Feng

    2011-01-01

    Recent studies indicate that the descending serotonin (5-HT) system from the rostral ventromedial medulla (RVM) in brainstem and the 5-HT3 receptor subtype in the spinal dorsal horn are involved in enhanced descending pain facilitation after tissue and nerve injury. However, the mechanisms underlying the activation of the 5-HT3 receptor and its contribution to facilitation of pain remain unclear. In the present study, activation of spinal 5-HT3 receptor by intrathecal injection of a selective 5-HT3 receptor agonist SR 57227 induced spinal glial hyperactivity, neuronal hyperexcitability and pain hypersensitivity in rats. We found that there was neuron-to-microglia signaling via chemokine fractalkine, microglia to astrocyte signaling via cytokine IL-18, astrocyte to neuronal signaling by IL-1β, and enhanced activation of GluN (NMDA) receptors in the spinal dorsal horn. In addition, exogenous BDNF-induced descending pain facilitation was accompanied with up-regulation of CD11b and GFAP expression in the spinal dorsal horn after microinjection in the RVM, which were significantly prevented by functional blockade of spinal 5-HT3 receptors. Enhanced expression of spinal CD11b and GFAP after hindpaw inflammation was also attenuated by molecular depletion of the descending 5-HT system by intra-RVM Tph-2 shRNA interference. Thus, these findings offer new insights into the cellular and molecular mechanisms at the spinal level responsible for descending 5-HT-mediated pain facilitation during the development of persistent pain after tissue and nerve injury. New pain therapies should focus on prime targets of descending facilitation-induced glial involvement, and in particular the blocking of intercellular signaling transduction between neuron and glia. PMID:21900561

  16. Activity of defined mushroom body output neurons underlies learned olfactory behavior in Drosophila.

    PubMed

    Owald, David; Felsenberg, Johannes; Talbot, Clifford B; Das, Gaurav; Perisse, Emmanuel; Huetteroth, Wolf; Waddell, Scott

    2015-04-22

    During olfactory learning in fruit flies, dopaminergic neurons assign value to odor representations in the mushroom body Kenyon cells. Here we identify a class of downstream glutamatergic mushroom body output neurons (MBONs) called M4/6, or MBON-β2β'2a, MBON-β'2mp, and MBON-γ5β'2a, whose dendritic fields overlap with dopaminergic neuron projections in the tips of the β, β', and γ lobes. This anatomy and their odor tuning suggests that M4/6 neurons pool odor-driven Kenyon cell synaptic outputs. Like that of mushroom body neurons, M4/6 output is required for expression of appetitive and aversive memory performance. Moreover, appetitive and aversive olfactory conditioning bidirectionally alters the relative odor-drive of M4β' neurons (MBON-β'2mp). Direct block of M4/6 neurons in naive flies mimics appetitive conditioning, being sufficient to convert odor-driven avoidance into approach, while optogenetically activating these neurons induces avoidance behavior. We therefore propose that drive to the M4/6 neurons reflects odor-directed behavioral choice.

  17. Cholesterol synthesis inhibitors protect against platelet-activating factor-induced neuronal damage

    PubMed Central

    Bate, Clive; Rumbold, Louis; Williams, Alun

    2007-01-01

    Background Platelet-activating factor (PAF) is implicated in the neuronal damage that accompanies ischemia, prion disease and Alzheimer's disease (AD). Since some epidemiological studies demonstrate that statins, drugs that reduce cholesterol synthesis, have a beneficial effect on mild AD, we examined the effects of two cholesterol synthesis inhibitors on neuronal responses to PAF. Methods Primary cortical neurons were treated with cholesterol synthesis inhibitors (simvastatin or squalestatin) prior to incubation with different neurotoxins. The effects of these drugs on neuronal cholesterol levels and neuronal survival were measured. Immunoblots were used to determine the effects of simvastatin or squalestatin on the distribution of the PAF receptor and an enzyme linked immunoassay was used to quantify the amounts of PAF receptor. Results PAF killed primary neurons in a dose-dependent manner. Pre-treatment with simvastatin or squalestatin reduced neuronal cholesterol and increased the survival of PAF-treated neurons. Neuronal survival was increased 50% by 100 nM simvastatin, or 20 nM squalestatin. The addition of mevalonate restored cholesterol levels, and reversed the protective effect of simvastatin. Simvastatin or squalestatin did not affect the amounts of the PAF receptor but did cause it to disperse from within lipid rafts. Conclusion Treatment of neurons with cholesterol synthesis inhibitors including simvastatin and squalestatin protected neurons against PAF. Treatment caused a percentage of the PAF receptors to disperse from cholesterol-sensitive domains. These results raise the possibility that the effects of statins on neurodegenerative disease are, at least in part, due to desensitisation of neurons to PAF. PMID:17233902

  18. Role of GABAA inhibition in modulation of pyramidal tract neuron activity during postural corrections

    PubMed Central

    Tamarova, Zinaida A; Sirota, Mikhail G; Orlovsky, Grigori N; Deliagina, Tatiana G; Beloozerova, Irina N

    2007-01-01

    In a previous study we demonstrated that the activity of pyramidal tract neurons (PTNs) of the motor cortex is modulated in relation to postural corrections evoked by periodical tilts of the animal. The modulation included an increase in activity in one phase of the tilt cycle and a decrease in the other phase. It is known that the motor cortex contains a large population of inhibitory GABAergic neurons. How do these neurons participate in periodic modulation of PTNs? The goal of this study was to investigate the role of GABAA inhibitory neurons of the motor cortex in the modulation of postural-related PTN activity. Using extracellular electrodes with attached micropipettes, we recorded the activity of PTNs in cats maintaining balance on a tilting platform both before and after iontophoretic application of the GABAA receptor antagonists gabazine or bicuculline. The tilt-related activity of 93% of PTNs was affected by GABAA receptor antagonists. In 88% of cells, peak activity increased by 75 ± 50% (mean ± SD). In contrast, the trough activity changed by a much smaller value and almost as many neurons showed a decrease as showed an increase. In 73% of the neurons, the phase position of the peak activity did not change or changed by no more than 0.1 of a cycle. We conclude that the GABAergic system of the motor cortex reduces the posture-related responses of PTNs but has little role in determining their response timing. PMID:17425574

  19. BPA Directly Decreases GnRH Neuronal Activity via Noncanonical Pathway.

    PubMed

    Klenke, Ulrike; Constantin, Stephanie; Wray, Susan

    2016-05-01

    Peripheral feedback of gonadal estrogen to the hypothalamus is critical for reproduction. Bisphenol A (BPA), an environmental pollutant with estrogenic actions, can disrupt this feedback and lead to infertility in both humans and animals. GnRH neurons are essential for reproduction, serving as an important link between brain, pituitary, and gonads. Because GnRH neurons express several receptors that bind estrogen, they are potential targets for endocrine disruptors. However, to date, direct effects of BPA on GnRH neurons have not been shown. This study investigated the effects of BPA on GnRH neuronal activity using an explant model in which large numbers of primary GnRH neurons are maintained and express many of the receptors found in vivo. Because oscillations in intracellular calcium have been shown to correlate with electrical activity in GnRH neurons, calcium imaging was used to assay the effects of BPA. Exposure to 50μM BPA significantly decreased GnRH calcium activity. Blockage of γ-aminobutyric acid ergic and glutamatergic input did not abrogate the inhibitory BPA effect, suggesting direct regulation of GnRH neurons by BPA. In addition to estrogen receptor-β, single-cell RT-PCR analysis confirmed that GnRH neurons express G protein-coupled receptor 30 (G protein-coupled estrogen receptor 1) and estrogen-related receptor-γ, all potential targets for BPA. Perturbation studies of the signaling pathway revealed that the BPA-mediated inhibition of GnRH neuronal activity occurred independent of estrogen receptors, GPER, or estrogen-related receptor-γ, via a noncanonical pathway. These results provide the first evidence of a direct effect of BPA on GnRH neurons.

  20. Melanocortin-3 receptors expressed in Nkx2.1(+ve) neurons are sufficient for controlling appetitive responses to hypocaloric conditioning

    PubMed Central

    Girardet, Clémence; Mavrikaki, Maria M.; Stevens, Joseph R.; Miller, Courtney A.; Marks, Daniel L.; Butler, Andrew A.

    2017-01-01

    Melanocortin-3 receptors (MC3R) have a contextual role in appetite control that is amplified with hypocaloric conditioning. C57BL/6J (B6) mice subjected to hypocaloric feeding schedules (HFS) exhibit compulsive behavioral responses involving food anticipatory activity (FAA) and caloric loading following food access. These homeostatic responses to calorie-poor environs are attenuated in B6 mice in which Mc3r transcription is suppressed by a lox-stop-lox sequence in the 5’UTR (Mc3rTB/TB). Here, we report that optimization of caloric loading in B6 mice subject to HFS, characterized by increased meal size and duration, is not observed in Mc3rTB/TB mice. Analysis of hypothalamic and neuroendocrine responses to HFS throughout the light-dark cycle suggests uncoupling of hypothalamic responses involving appetite-stimulating fasting-responsive hypothalamic neurons expressing agouti-related peptide (AgRP) and neuropeptide Y (Npy). Rescuing Mc3rs expression in Nkx2.1(+ve) neurons is sufficient to restore normal hypothalamic responses to negative energy balance. In addition, Mc3rs expressed in Nkx2.1(+ve) neurons are also sufficient to restore FAA and caloric loading of B6 mice subjected to HFS. In summary, MC3Rs expressed in Nkx2.1(+ve) neurons are sufficient to coordinate hypothalamic response and expression of compulsive behavioral responses involving meal anticipation and consumption of large meals during situations of prolonged negative energy balance. PMID:28294152

  1. Differential effects of histamine on the activity of hypothalamic dopaminergic neurons in the rat.

    PubMed

    Fleckenstein, A E; Lookingland, K J; Moore, K E

    1994-01-01

    The effect of intracerebroventricular administration of histamine on hypothalamic dopaminergic neuronal activity was estimated in male rats by measuring concentrations of dopamine and its metabolite 3,4-dihydroxyphenylacetic acid (DOPAC) in brain regions containing terminals or perikarya of these neurons. Three distinct, regionally specific neurochemical responses were apparent. In the median eminence and intermediate lobe of the pituitary, histamine affected neither DOPAC nor dopamine concentrations, suggesting no effect on tuberoinfundibular or periventricular-hypophysial dopaminergic neuronal activity. In the medial zona incerta and in the dorsomedial, rostral periventricular and medial preoptic hypothalamic nuclei, histamine effected a dose- and time-related increase in both DOPAC and dopamine concentrations; these effects were blocked by destruction of noradrenergic neurons projecting to these regions, suggesting that these changes are attributable to noradrenergic neuronal activation, and that histamine does not affect the activity of incertohypothalamic or periventricular-preoptic dopaminergic neurons located in these brain regions. In the suprachiasmatic, caudal periventricular and paraventricular hypothalamic nuclei, histamine effected a dose- and time-related increase in DOPAC, but not dopamine, concentrations; these effects were blocked by the H1 antagonist mepyramine, but not the H2 antagonist zolantidine. Destruction of noradrenergic neurons projecting to these regions did not prevent the histamine-induced increases in DOPAC concentrations. These data indicate that histamine increases the activity of dopaminergic neurons projecting to the suprachiasmatic, caudal periventricular and paraventricular nuclei via an action at H1 receptors. Overall, these results reveal that i.c.v. administration of histamine differentially affects the activity of the various dopaminergic neuronal systems of the rat hypothalamus.

  2. DELTAMETHRIN AND PERMETHRIN DECREASE SPONTANEOUS ACTIVITY IN NEURONAL NETWORKS IN VITRO.

    EPA Science Inventory

    Effects of pyrethroid insecticides on spontaneous electrical activity were investigated in primary cultures of cortical or spinal cord neurons grown on microelectrode arrays. Bicuculline (40 ¿M) was utilized to block fast GABAergic transmission, and concentration-dependent effect...

  3. Ghrelin activates hypophysiotropic corticotropin-releasing factor neurons independently of the arcuate nucleus.

    PubMed

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

    2016-05-01

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

  4. Neuroprotective effects of active ingredients isolated from Pegasus laternarius on cultured cerebral neurons.

    PubMed

    Li, Mengtao; Chen, Minhui; Huang, Hai; Tao, Wucheng; Cui, Jihong; Xiang, Hui

    2011-01-01

    Seamoth (Pegasus laternarius Cuvier) is extensively used to treat various diseases on the coastland of Guangdong Province in China, such as scrofula, cough, and diarrhea. The total extract of Pegasus laternarius (EP) was subjected to column chromatography to acquire three different constituents (EPC1, EPC2, and EPC3). Cerebral neuron injury was induced by glutamate, H₂O₂, and serum deprivation. After treating with or without different extracts, cell viability was assessed with the MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, and cell apoptosis was analyzed with Hoechst 33258 staining and agarose gel electrophoresis. We also determined the levels of lactate dehydrogenase (LDH), maleic dialdehyde (MDA), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px). The results showed that both EP and EPC2 promoted the outgrowth of cultural neurons, increased antioxidant enzyme activity, and protected neurons from neuronal injury or apoptosis induced by glutamate, H₂O₂, and serum deprivation. EPC1 and EPC3 had little or no effect on neurons. These results suggest that the active ingredients obtained from Pegasus laternarius have potential neuroprotective effects on injured neurons by promoting the outgrowth of cultured neurons, increasing the activity of intracellular antioxidants, and exerting antiapoptotic effects. This neuroprotection may be attributable to specific active ingredients, such as taurine, novel ceramide, and cholesterol.

  5. Evidence for evolutionary divergence of activity-dependent gene expression in developing neurons

    PubMed Central

    Qiu, Jing; McQueen, Jamie; Bilican, Bilada; Dando, Owen; Magnani, Dario; Punovuori, Karolina; Selvaraj, Bhuvaneish T; Livesey, Matthew; Haghi, Ghazal; Heron, Samuel; Burr, Karen; Patani, Rickie; Rajan, Rinku; Sheppard, Olivia; Kind, Peter C; Simpson, T Ian; Tybulewicz, Victor LJ; Wyllie, David JA; Fisher, Elizabeth MC; Lowell, Sally; Chandran, Siddharthan; Hardingham, Giles E

    2016-01-01

    Evolutionary differences in gene regulation between humans and lower mammalian experimental systems are incompletely understood, a potential translational obstacle that is challenging to surmount in neurons, where primary tissue availability is poor. Rodent-based studies show that activity-dependent transcriptional programs mediate myriad functions in neuronal development, but the extent of their conservation in human neurons is unknown. We compared activity-dependent transcriptional responses in developing human stem cell-derived cortical neurons with those induced in developing primary- or stem cell-derived mouse cortical neurons. While activity-dependent gene-responsiveness showed little dependence on developmental stage or origin (primary tissue vs. stem cell), notable species-dependent differences were observed. Moreover, differential species-specific gene ortholog regulation was recapitulated in aneuploid mouse neurons carrying human chromosome-21, implicating promoter/enhancer sequence divergence as a factor, including human-specific activity-responsive AP-1 sites. These findings support the use of human neuronal systems for probing transcriptional responses to physiological stimuli or indeed pharmaceutical agents. DOI: http://dx.doi.org/10.7554/eLife.20337.001 PMID:27692071

  6. Ionic mechanism underlying recovery of rhythmic activity in adult isolated neurons

    PubMed Central

    Haedo, Rodolfo J.; Golowasch, Jorge

    2013-01-01

    Neurons exhibit long-term excitability changes necessary for maintaining proper cell and network activity in response to various inputs and perturbations. For instance, the adult crustacean pyloric network can spontaneously recover rhythmic activity after complete shutdown resulting from permanent removal of neuromodulatory inputs. Dissociated lobster stomatogastric ganglion (STG) neurons have been shown to spontaneously develop oscillatory activity via excitability changes. Rhythmic electrical stimulation can eliminate these oscillatory patterns in some cells. The ionic mechanisms underlying these changes are only partially understood. We used dissociated crab STG neurons to study the ionic mechanisms underlying spontaneous recovery of rhythmic activity and stimulation-induced activity changes. Similar to lobster neurons, rhythmic activity spontaneously develops in crab STG neurons. Rhythmic hyperpolarizing stimulation can eliminate, but more commonly accelerate the emergence of stable oscillatory activity depending on Ca++ influx at hyperpolarized voltages. Our main finding is that up-regulation of a Ca++-current and down-regulation of a high-threshold K+-current underlies the spontaneous homeostatic development of oscillatory activity. However, because of a non-linear dependence on stimulus frequency, hyperpolarization-induced oscillations appear to be inconsistent with a homeostatic regulation of activity. We find no difference in the activity patterns or the underlying ionic currents involved between neurons of the fast pyloric and the slow gastric mill networks during the first ten days in isolation. Dynamic-clamp experiments confirm that these conductance modifications can explain the observed activity changes. We conclude that spontaneous and stimulation-induced excitability changes in STG neurons can both result in intrinsic oscillatory activity via regulation of the same two conductances. PMID:16807346

  7. Closed-form expressions of some stochastic adapting equations for nonlinear adaptive activation function neurons.

    PubMed

    Fiori, Simone

    2003-12-01

    In recent work, we introduced nonlinear adaptive activation function (FAN) artificial neuron models, which learn their activation functions in an unsupervised way by information-theoretic adapting rules. We also applied networks of these neurons to some blind signal processing problems, such as independent component analysis and blind deconvolution. The aim of this letter is to study some fundamental aspects of FAN units' learning by investigating the properties of the associated learning differential equation systems.

  8. Dehydration-induced modulation of kappa-opioid inhibition of vasopressin neurone activity.

    PubMed

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

    2009-12-01

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

  9. NSAIDs modulate GABA-activated currents via Ca2+-activated Cl− channels in rat dorsal root ganglion neurons

    PubMed Central

    ZHAO, LEI; LI, LI; MA, KE-TAO; WANG, YANG; LI, JING; SHI, WEN-YAN; ZHU, HE; ZHANG, ZHONG-SHUANG; SI, JUN-QIANG

    2016-01-01

    The ability of non-steroidal anti-inflammatory drugs (NSAIDs) to modulate γ-aminobutyrate (GABA)-activated currents via Ca2+-activated Cl− channels in rat dorsal root ganglion neurons (DRG), was examined in the present study. During the preparation of DRG neurons harvested from Sprague-Dawley rats, the whole-cell recording technique was used to record the effect of NSAIDs on GABA-activated inward currents, and the expression levels of the TMEM16A and TMEM16B subunits were revealed. In the event that DRG neurons were pre-incubated for 20 sec with niflumic acid (NFA) and 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB) prior to the administration of GABA, the GABA-induced inward currents were diminished markedly in the majority of neurons examined (96.3%). The inward currents induced by 100 µmol/l GABA were attenuated by (0±0.09%; neurons = 4), (5.32±3.51%; neurons = 6), (21.3±4.00%; neurons = 5), (33.8±5.20%; neurons = 17), (52.2±5.10%; neurons = 4) and (61.1±4.12%; neurons = 12) by 0.1, 1, 3, 10, 30 and 100 µmol/l NFA, respectively. The inward currents induced by 100 µmol/l GABA were attenuated by (13.8±6%; neurons = 6), (23.2±14.7%; neurons = 6) and (29.7±9.1%; neurons = 9) by 3, 10 and 30 µmol/l NPPB, respectively. NFA and NPPB dose-dependently inhibited GABA-activated currents with half maximal inhibitory concentration (IC50) values of 6.7 and 11 µmol/l, respectively. The inhibitory effect of 100 µmol/l NFA on the GABA-evoked inward current were also strongly inhibited by nitrendipine (NTDP; an L-type calcium channel blocker), 1,2-bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid tetrakis (a highly selective calcium chelating reagent), caffeine (a widely available Ca2+ consuming drug) and calcium-free extracellular fluid, in a concentration-dependent manner. Immunofluorescent staining indicated that TMEM16A and TMEM16B expression was widely distributed in DRG neurons. The results suggest that NSAIDs may be able to regulate Ca2

  10. Leptin regulated calcium channels of neuropeptide Y and proopiomelanocortin neurons by activation of different signal pathways.

    PubMed

    Wang, J-H; Wang, F; Yang, M-J; Yu, D-F; Wu, W-N; Liu, J; Ma, L-Q; Cai, F; Chen, J-G

    2008-09-22

    The fat-derived hormone leptin regulates food intake and body weight in part by modulating the activity of neuropeptide Y (NPY) and proopiomelanocortin (POMC) neurons in the hypothalamic arcuate nucleus (ARC). To investigate the electrophysiological activity of these neurons and their responses to leptin, we recorded whole-cell calcium currents on NPY and POMC neurons in the ARC of rats, which we identified by morphologic features and immunocytochemical identification at the end of recording. Leptin decreased the peak amplitude of high voltage-activated calcium currents (I(HVA)) in the isolated neurons from ARC, which were subsequently shown to be immunoreactive for NPY. The inhibition was prevented by pretreatment with inhibitors of Janus kinase 2 (JAK2) and mitogen-activated protein kinases (MAPK). In contrast, leptin increased the amplitude of I(HVA) in POMC-containing neurons. The stimulations of I(HVA) were inhibited by blockers of JAK2 and phosphatidylino 3-kinase (PI3-k). Both of these effects were counteracted by the L-type calcium channel antagonist nifedipine, suggesting that L-type calcium channels were involved in the regulation induced by leptin. These data indicated that leptin exerted opposite effects on these two classes of neurons. Leptin directly inhibited I(HVA) in NPY neurons via leptin receptor (LEPR) -JAK2-MAPK pathways, whereas evoked I(HVA) in POMC neurons by LEPR-JAK2-PI3-k pathways. These neural pathways and intracellular signaling mechanisms may play key roles in regulating NPY and POMC neuron activity, anorectic action of leptin and, thereby, feeding.

  11. Active dentate granule cells encode experience to promote the addition of adult-born hippocampal neurons.

    PubMed

    Kirschen, Gregory W; Shen, Jia; Tian, Mu; Schroeder, Bryce; Wang, Jia; Man, Guoming; Wu, Song; Ge, Shaoyu

    2017-04-03

    The continuous addition of new dentate granule cells, exquisitely regulated by brain activity, renders the hippocampus plastic. However, how neural circuits encode experiences to impact the addition of adult-born neurons remains unknown. Here, we used endoscopic Ca(2+) imaging to track the real-time activity of individual dentate granule cells in freely-behaving mice. For the first time, we found that active dentate granule cells responded to a novel experience by preferentially increasing their Ca(2+) event frequency. This elevated activity, which we found to be associated with object exploration, returned to baseline by one hour in the same environment, but could be dishabituated via introduction to a novel environment. To seamlessly transition between environments, we next established a freely-controllable virtual reality system for unrestrained mice. We again observed increased firing of active neurons in a virtual enriched environment. Interestingly, multiple novel virtual experiences accumulatively increased the number of newborn neurons when compared to a single experience. Finally, optogenetic silencing of existing dentate granule cells during novel environmental exploration perturbed experience-induced neuronal addition. Together, our study shows that the adult brain conveys novel, enriched experiences to increase the addition of adult-born hippocampal neurons by increasing the firing of active dentate granule cells.SIGNIFICANCE STATEMENTAdult brains are constantly reshaping themselves from synapses to circuits as we encounter novel experiences from moment to moment. Importantly, this reshaping includes the addition of newborn hippocampal neurons. However, it remains largely unknown how our circuits encode experience-induced brain activity to govern the addition of new hippocampal neurons. By coupling in vivo Ca(2+) imaging of dentate granule neurons with a novel unrestrained virtual reality system for rodents, we discovered that a new experience rapidly

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

    PubMed Central

    Mitra, Arojit; Guèvremont, Geneviève; Timofeeva, Elena

    2016-01-01

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

  13. 50 Hz-Sinusoidal magnetic field induced effects on the bioelectric activity of single unit neurone cells

    NASA Astrophysics Data System (ADS)

    Azanza, María. J.; Calvo, Ana C.; del Moral, A.

    2001-05-01

    Neurones recruiting and synchronized bioelectric activity recorded from Helix aspersa brain ganglia, under exposure to 50 Hz sinusoidal magnetic fields of 1-15 mT intensity, is reported. We show recruiting responses from single neurones and the synchronization of pairs of neurones activity. Experimental evidence and model theoretical explanation for the spreading of synchronization are presented.

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

    PubMed

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

    2013-08-01

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

  15. Prosthetic systems for therapeutic optical activation and silencing of genetically-targeted neurons

    NASA Astrophysics Data System (ADS)

    Bernstein, Jacob G.; Han, Xue; Henninger, Michael A.; Ko, Emily Y.; Qian, Xiaofeng; Talei Franzesi, Giovanni; McConnell, Jackie P.; Stern, Patrick; Desimone, Robert; Boyden, Edward S.

    2008-02-01

    Many neural disorders are associated with aberrant activity in specific cell types or neural projection pathways embedded within the densely-wired, heterogeneous matter of the brain. An ideal therapy would permit correction of activity just in specific target neurons, while leaving other neurons unaltered. Recently our lab revealed that the naturally-occurring light-activated proteins channelrhodopsin-2 (ChR2) and halorhodopsin (Halo/NpHR) can, when genetically expressed in neurons, enable them to be safely, precisely, and reversibly activated and silenced by pulses of blue and yellow light, respectively. We here describe the ability to make specific neurons in the brain light-sensitive, using a viral approach. We also reveal the design and construction of a scalable, fully-implantable optical prosthetic capable of delivering light of appropriate intensity and wavelength to targeted neurons at arbitrary 3-D locations within the brain, enabling activation and silencing of specific neuron types at multiple locations. Finally, we demonstrate control of neural activity in the cortex of the non-human primate, a key step in the translation of such technology for human clinical use. Systems for optical targeting of specific neural circuit elements may enable a new generation of high-precision therapies for brain disorders.

  16. Size-dependent regulation of synchronized activity in living neuronal networks

    NASA Astrophysics Data System (ADS)

    Yamamoto, Hideaki; Kubota, Shigeru; Chida, Yudai; Morita, Mayu; Moriya, Satoshi; Akima, Hisanao; Sato, Shigeo; Hirano-Iwata, Ayumi; Tanii, Takashi; Niwano, Michio

    2016-07-01

    We study the effect of network size on synchronized activity in living neuronal networks. Dissociated cortical neurons form synaptic connections in culture and generate synchronized spontaneous activity within 10 days in vitro. Using micropatterned surfaces to extrinsically control the size of neuronal networks, we show that synchronized activity can emerge in a network as small as 12 cells. Furthermore, a detailed comparison of small (˜20 cells), medium (˜100 cells), and large (˜400 cells) networks reveal that synchronized activity becomes destabilized in the small networks. A computational modeling of neural activity is then employed to explore the underlying mechanism responsible for the size effect. We find that the generation and maintenance of the synchronized activity can be minimally described by: (1) the stochastic firing of each neuron in the network, (2) enhancement in the network activity in a positive feedback loop of excitatory synapses, and (3) Ca-dependent suppression of bursting activity. The model further shows that the decrease in total synaptic input to a neuron that drives the positive feedback amplification of correlated activity is a key factor underlying the destabilization of synchrony in smaller networks. Spontaneous neural activity plays a critical role in cortical information processing, and our work constructively clarifies an aspect of the structural basis behind this.

  17. Size-dependent regulation of synchronized activity in living neuronal networks.

    PubMed

    Yamamoto, Hideaki; Kubota, Shigeru; Chida, Yudai; Morita, Mayu; Moriya, Satoshi; Akima, Hisanao; Sato, Shigeo; Hirano-Iwata, Ayumi; Tanii, Takashi; Niwano, Michio

    2016-07-01

    We study the effect of network size on synchronized activity in living neuronal networks. Dissociated cortical neurons form synaptic connections in culture and generate synchronized spontaneous activity within 10 days in vitro. Using micropatterned surfaces to extrinsically control the size of neuronal networks, we show that synchronized activity can emerge in a network as small as 12 cells. Furthermore, a detailed comparison of small (∼20 cells), medium (∼100 cells), and large (∼400 cells) networks reveal that synchronized activity becomes destabilized in the small networks. A computational modeling of neural activity is then employed to explore the underlying mechanism responsible for the size effect. We find that the generation and maintenance of the synchronized activity can be minimally described by: (1) the stochastic firing of each neuron in the network, (2) enhancement in the network activity in a positive feedback loop of excitatory synapses, and (3) Ca-dependent suppression of bursting activity. The model further shows that the decrease in total synaptic input to a neuron that drives the positive feedback amplification of correlated activity is a key factor underlying the destabilization of synchrony in smaller networks. Spontaneous neural activity plays a critical role in cortical information processing, and our work constructively clarifies an aspect of the structural basis behind this.

  18. Monoclonal antibody to microtubule-associated STOP protein: affinity purification of neuronal STOP activity and comparison of antigen with activity in neuronal and nonneuronal cell extracts.

    PubMed

    Pirollet, F; Rauch, C T; Job, D; Margolis, R L

    1989-01-24

    Microtubules, ordinarily cold-labile structures, are made entirely resistant to cold temperature by the presence of substoichiometric amounts of STOP (stable tubule only polypeptide), a microtubule-associated protein. We have produced a monoclonal antibody which specifically recognizes a 145-kDa protein previously implicated in STOP activity in rat brain extracts. An antibody affinity column removes both the 145-kDa protein and STOP activity from solution. A urea eluate from the affinity column contains the 145-kDa protein and exhibits substantial STOP activity. We conclude the 145-kDa protein accounts for all measurable STOP activity in rat neuronal extracts. For this work, we have developed an assay of microtubule cold stability which is generally applicable to the detection of STOP activity in various tissues. Using this assay, we show STOP activity is most abundant in neuronal tissue but is detectable in all tissues tested, with the exception of heart muscle. In all tissues that we have examined, STOP activity elutes as a single peak from heparin affinity columns, and in common with brain STOP, all activity is Ca2+-calmodulin sensitive. The monoclonal antibody recognizes the 145-kDa STOP in rat neuronal extracts but reacts with no protein in active fractions from other tissue. A similar, but not identical, analogue of brain STOP thus appears to be widespread in mammalian tissues.

  19. Chd7 is indispensable for mammalian brain development through activation of a neuronal differentiation programme

    PubMed Central

    Feng, Weijun; Kawauchi, Daisuke; Körkel-Qu, Huiqin; Deng, Huan; Serger, Elisabeth; Sieber, Laura; Lieberman, Jenna Ariel; Jimeno-González, Silvia; Lambo, Sander; Hanna, Bola S.; Harim, Yassin; Jansen, Malin; Neuerburg, Anna; Friesen, Olga; Zuckermann, Marc; Rajendran, Vijayanad; Gronych, Jan; Ayrault, Olivier; Korshunov, Andrey; Jones, David T. W.; Kool, Marcel; Northcott, Paul A.; Lichter, Peter; Cortés-Ledesma, Felipe; Pfister, Stefan M.; Liu, Hai-Kun

    2017-01-01

    Mutations in chromatin modifier genes are frequently associated with neurodevelopmental diseases. We herein demonstrate that the chromodomain helicase DNA-binding protein 7 (Chd7), frequently associated with CHARGE syndrome, is indispensable for normal cerebellar development. Genetic inactivation of Chd7 in cerebellar granule neuron progenitors leads to cerebellar hypoplasia in mice, due to the impairment of granule neuron differentiation, induction of apoptosis and abnormal localization of Purkinje cells, which closely recapitulates known clinical features in the cerebella of CHARGE patients. Combinatory molecular analyses reveal that Chd7 is required for the maintenance of open chromatin and thus activation of genes essential for granule neuron differentiation. We further demonstrate that both Chd7 and Top2b are necessary for the transcription of a set of long neuronal genes in cerebellar granule neurons. Altogether, our comprehensive analyses reveal a mechanism with chromatin remodellers governing brain development via controlling a core transcriptional programme for cell-specific differentiation. PMID:28317875

  20. Chd7 is indispensable for mammalian brain development through activation of a neuronal differentiation programme.

    PubMed

    Feng, Weijun; Kawauchi, Daisuke; Körkel-Qu, Huiqin; Deng, Huan; Serger, Elisabeth; Sieber, Laura; Lieberman, Jenna Ariel; Jimeno-González, Silvia; Lambo, Sander; Hanna, Bola S; Harim, Yassin; Jansen, Malin; Neuerburg, Anna; Friesen, Olga; Zuckermann, Marc; Rajendran, Vijayanad; Gronych, Jan; Ayrault, Olivier; Korshunov, Andrey; Jones, David T W; Kool, Marcel; Northcott, Paul A; Lichter, Peter; Cortés-Ledesma, Felipe; Pfister, Stefan M; Liu, Hai-Kun

    2017-03-20

    Mutations in chromatin modifier genes are frequently associated with neurodevelopmental diseases. We herein demonstrate that the chromodomain helicase DNA-binding protein 7 (Chd7), frequently associated with CHARGE syndrome, is indispensable for normal cerebellar development. Genetic inactivation of Chd7 in cerebellar granule neuron progenitors leads to cerebellar hypoplasia in mice, due to the impairment of granule neuron differentiation, induction of apoptosis and abnormal localization of Purkinje cells, which closely recapitulates known clinical features in the cerebella of CHARGE patients. Combinatory molecular analyses reveal that Chd7 is required for the maintenance of open chromatin and thus activation of genes essential for granule neuron differentiation. We further demonstrate that both Chd7 and Top2b are necessary for the transcription of a set of long neuronal genes in cerebellar granule neurons. Altogether, our comprehensive analyses reveal a mechanism with chromatin remodellers governing brain development via controlling a core transcriptional programme for cell-specific differentiation.

  1. Evidence supporting the existence of an activity-dependent astrocyte-neuron lactate shuttle.

    PubMed

    Pellerin, L; Pellegri, G; Bittar, P G; Charnay, Y; Bouras, C; Martin, J L; Stella, N; Magistretti, P J

    1998-01-01

    Mounting evidence from in vitro experiments indicates that lactate is an efficient energy substrate for neurons and that it may significantly contribute to maintain synaptic transmission, particularly during periods of intense activity. Since lactate does not cross the blood-brain barrier easily, blood-borne lactate cannot be a significant source. In vitro studies by several laboratories indicate that astrocytes release large amounts of lactate. In 1994, we proposed a mechanism whereby lactate could be produced by astrocytes in an activity-dependent, glutamate-mediated manner. Over the last 2 years we have obtained further evidence supporting the notion that a transfer of lactate from astrocytes to neurons might indeed take place. In this article, we first review data showing the presence of mRNA encoding for two monocarboxylate transporters, MCT1 and MCT2, in the adult mouse brain. Second, by using monoclonal antibodies selectively directed against the two distinct lactate dehydrogenase isoforms, LDH1 and LDH5, a specific cellular distribution between neurons and astrocytes is revealed which suggests that a population of astrocytes is a lactate 'source' while neurons may be a lactate 'sink'. Third, we provide biochemical evidence that lactate is interchangeable with glucose to support oxidative metabolism in cortical neurons. This set of data is consistent with the existence of an activity-dependent astrocyte-neuron lactate shuttle for the supply of energy substrates to neurons.

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

    PubMed

    Liraz, Ori; Rosenblum, Kobi; Barkai, Edi

    2009-01-01

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

  3. CAMKII Activation Is Not Required for Maintenance of Learning-Induced Enhancement of Neuronal Excitability

    PubMed Central

    Liraz, Ori; Rosenblum, Kobi; Barkai, Edi

    2009-01-01

    Pyramidal neurons in the piriform cortex from olfactory-discrimination trained rats show enhanced intrinsic neuronal excitability that lasts for several days after learning. Such enhanced intrinsic excitability is mediated by long-term reduction in the post-burst after-hyperpolarization (AHP) which is generated by repetitive spike firing. AHP reduction is due to decreased conductance of a calcium-dependent potassium current, the sIAHP. We have previously shown that learning-induced AHP reduction is maintained by persistent protein kinase C (PKC) and extracellular regulated kinase (ERK) activation. However, the molecular machinery underlying this long-lasting modulation of intrinsic excitability is yet to be fully described. Here we examine whether the CaMKII, which is known to be crucial in learning, memory and synaptic plasticity processes, is instrumental for the maintenance of learning-induced AHP reduction. KN93, that selectively blocks CaMKII autophosphorylation at Thr286, reduced the AHP in neurons from trained and control rat to the same extent. Consequently, the differences in AHP amplitude and neuronal adaptation between neurons from trained rats and controls remained. Accordingly, the level of activated CaMKII was similar in pirifrom cortex samples taken form trained and control rats. Our data show that although CaMKII modulates the amplitude of AHP of pyramidal neurons in the piriform cortex, its activation is not required for maintaining learning-induced enhancement of neuronal excitability. PMID:19172997

  4. CNTF-Treated Astrocyte Conditioned Medium Enhances Large-Conductance Calcium-Activated Potassium Channel Activity in Rat Cortical Neurons.

    PubMed

    Sun, Meiqun; Liu, Hongli; Xu, Huanbai; Wang, Hongtao; Wang, Xiaojing

    2016-08-01

    Seizure activity is linked to astrocyte activation as well as dysfunctional cortical neuron excitability produced from changes in calcium-activated potassium (KCa) channel function. Ciliary neurotrophic factor-treated astrocyte conditioned medium (CNTF-ACM) can be used to investigate the peripheral effects of activated astrocytes upon cortical neurons. However, CNTF-ACM's effect upon KCa channel activity in cultured cortical neurons has not yet been investigated. Whole-cell patch clamp recordings were performed in rat cortical neurons to evaluate CNTF-ACM's effects upon charybdotoxin-sensitive large-conductance KCa (BK) channel currents and apamin-sensitive small-conductance KCa (SK) channel current. Biotinylation and RT-PCR were applied to assess CNTF-ACM's effects upon the protein and mRNA expression, respectively, of the SK channel subunits SK2 and SK3 and the BK channel subunits BKα1 and BKβ3. An anti-fibroblast growth factor-2 (FGF-2) monoclonal neutralizing antibody was used to assess the effects of the FGF-2 component of CNTF-ACM. CNTF-ACM significantly increased KCa channel current density, which was predominantly attributable to gains in BK channel activity (p < 0.05). CNTF-ACM produced a significant increase in BKα1 and BKβ3 expression (p < 0.05) but had no significant effect upon SK2 or SK3 expression (p > 0.05). Blocking FGF-2 produced significant reductions in KCa channel current density (p > 0.05) as well as BKα1 and BKβ3 expression in CNTF-ACM-treated neurons (p > 0.05). CNTF-ACM significantly enhances BK channel activity in rat cortical neurons and that FGF-2 is partially responsible for these effects. CNTF-induced astrocyte activation results in secretion of neuroactive factors which may affect neuronal excitability and resultant seizure activity in mammalian cortical neurons.

  5. Nucleus accumbens neuronal activity correlates to the animal's behavioral response to acute and chronic methylphenidate.

    PubMed

    Claussen, Catherine M; Chong, Samuel L; Dafny, Nachum

    2014-04-22

    Acute and chronic methylphenidate (MPD) exposure was recorded simultaneously for the rat's locomotor activity and the nucleus accumbens (NAc) neuronal activity. The evaluation of the neuronal events was based on the animal's behavior response to chronic MPD administration: 1) Animals exhibiting behavioral sensitization, 2) Animals exhibiting behavioral tolerance. The experiment lasted for 10days with four groups of animals; saline, 0.6, 2.5, and 10.0mg/kg MPD. For the main behavioral findings, about half of the animals exhibited behavioral sensitization or behavioral tolerance to 0.6, 2.5, and/or 10mg/kg MPD respectively. Three hundred and forty one NAc neuronal units were evaluated. Approximately 80% of NAc units responded to 0.6, 2.5, and 10.0mg/kg MPD. When the neuronal activity was analyzed based on the animals' behavioral response to chronic MPD exposure, significant differences were seen between the neuronal population responses recorded from animals that expressed behavioral sensitization when compared to the NAc neuronal responses recorded from animals exhibiting behavioral tolerance. Three types of neurophysiological sensitization and neurophysiological tolerance can be recognized following chronic MPD administration to the neuronal populations. Collectively, these findings show that the same dose of chronic MPD can elicit either behavioral tolerance or behavioral sensitization. Differential statistical analyses were used to verify our hypothesis that the neuronal activity recorded from animals exhibiting behavioral sensitization will respond differently to MPD compared to those animals exhibiting behavioral tolerance, thus, suggesting that it is essential to record the animal's behavior concomitantly with neuronal recordings.

  6. Mechanisms of protease-activated receptor 2-evoked hyperexcitability of nociceptive neurons innervating the mouse colon

    PubMed Central

    Kayssi, Ahmed; Amadesi, Silvia; Bautista, Francisco; Bunnett, Nigel W; Vanner, Stephen

    2007-01-01

    Agonists of protease-activated receptor 2 (PAR2) evoke hyperexcitability of dorsal root ganglia (DRG) neurons by unknown mechanisms. We examined the cellular mechanisms underlying PAR2-evoked hyperexcitability of mouse colonic DRG neurons to determine their potential role in pain syndromes such as visceral hyperalgesia. Colonic DRG neurons were identified by injecting Fast Blue and DiI retrograde tracers into the mouse colon. Using immunofluorescence, we found that DiI-labelled neurons contained PAR2 immunoreactivity, confirming the presence of receptors on colonic neurons. Whole-cell current-clamp recordings of acutely dissociated neurons demonstrated that PAR2 activation with a brief application (3 min) of PAR2 agonists, SLIGRL-NH2 and trypsin, evoked sustained depolarizations (up to 60 min) which were associated with increased input resistance and a marked reduction in rheobase (50% at 30 min). In voltage clamp, SLIGRL-NH2 markedly suppressed delayed rectifier IK currents (55% at 10 min), but had no effect on the transient IA current or TTX-resistant Na+ currents. In whole-cell current-clamp recordings, the sustained excitability evoked by PAR2 activation was blocked by the PKC inhibitor, calphostin, and the ERK1/2 inhibitor PD98059. Studies of ERK1/2 phosphorylation using confocal microscopy demonstrated that SLIGRL-NH2 increased levels of immunoreactive pERK1/2 in DRG neurons, particularly in proximity to the plasma membrane. Thus, activation of PAR2 receptors on colonic nociceptive neurons causes sustained hyperexcitability that is related, at least in part, to suppression of delayed rectifier IK currents. Both PKC and ERK1/2 mediate the PAR2-induced hyperexcitability. These studies describe a novel mechanism of sensitization of colonic nociceptive neurons that may be implicated in conditions of visceral hyperalgesia such as irritable bowel syndrome. PMID:17289784

  7. Motor Neurons Tune Premotor Activity in a Vertebrate Central Pattern Generator.

    PubMed

    Lawton, Kristy J; Perry, Wick M; Yamaguchi, Ayako; Zornik, Erik

    2017-03-22

    Central patterns generators (CPGs) are neural circuits that drive rhythmic motor output without sensory feedback. Vertebrate CPGs are generally believed to operate in a top-down manner in which premotor interneurons activate motor neurons that in turn drive muscles. In contrast, the frog (Xenopus laevis) vocal CPG contains a functionally unexplored neuronal projection from the motor nucleus to the premotor nucleus, indicating a recurrent pathway that may contribute to rhythm generation. In this study, we characterized the function of this bottom-up connection. The X. laevis vocal CPG produces a 50-60 Hz "fast trill" song used by males during courtship. We recorded "fictive vocalizations" in the in vitro CPG from the laryngeal nerve while simultaneously recording premotor activity at the population and single-cell level. We show that transecting the motor-to-premotor projection eliminated the characteristic firing rate of premotor neurons. Silencing motor neurons with the intracellular sodium channel blocker QX-314 also disrupted premotor rhythms, as did blockade of nicotinic synapses in the motor nucleus (the putative location of motor neuron-to-interneuron connections). Electrically stimulating the laryngeal nerve elicited primarily IPSPs in premotor neurons that could be blocked by a nicotinic receptor antagonist. Our results indicate that an inhibitory signal, activated by motor neurons, is required for proper CPG function. To our knowledge, these findings represent the first example of a CPG in which precise premotor rhythms are tuned by motor neuron activity.SIGNIFICANCE STATEMENT Central pattern generators (CPGs) are neural circuits that produce rhythmic behaviors. In vertebrates, motor neurons are not commonly known to contribute to CPG function, with the exception of a few spinal circuits where the functional significance of motor neuron feedback is still poorly understood. The frog hindbrain vocal circuit contains a previously unexplored connection from

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

    PubMed

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

    2012-04-15

    Previous studies have indicated that there is increased activation of the paraventricular nucleus (PVN) in rats with chronic heart failure (CHF); however, it is not clear if the preautonomic neurons within the PVN are specifically overactive. Also, it is not known if these neurons have altered responses to baroreceptor or osmotic challenges. Experiments were conducted in rats with CHF (6-8 wk after coronary artery ligation). Spontaneously active neurons were recorded in the PVN, of which 36% were antidromically activated from the rostral ventrolateral medulla (RVLM). The baseline discharge rate in RVLM-projecting PVN (PVN-RVLM) neurons from CHF rats was significantly greater than in sham-operated (sham) rats (6.0 ± 0.6 vs. 2.6 ± 0.3 spikes/s, P < 0.05). Picoinjection of the N-methyl-D-aspartate (NMDA) receptor antagonist D,L-2-amino-5-phosphonovaleric acid significantly decreased the basal discharge of PVN-RVLM neurons by 80% in CHF rats compared with 37% in sham rats. Fifty-two percent of spontaneously active PVN-RVLM neurons responded to changes in the mean arterial pressure (MAP). The changes in discharge rate in PVN-RVLM neurons after a reduction in MAP (+52 ± 7% vs. +184 ± 61%) or an increase in MAP (-42 ± 8% vs. -71 ± 6%) were significantly attenuated in rats with CHF compared with sham rats. Most PVN-RVLM neurons (63%), including all barosensitive PVN-RVLM neurons, were excited by an internal carotid artery injection of hypertonic NaCl (2.1 osmol/l), whereas a smaller number (7%) were inhibited. The increase in discharge rate in PVN-RVLM neurons to hypertonic stimulation was significantly enhanced in rats with CHF compared with sham rats (134 ± 15% vs. 92 ± 13%). Taken together, these data suggest that PVN-RVLM neurons are more active under basal conditions and this overactivation is mediated by an enhanced glutamatergic tone in rats with CHF. Furthermore, this enhanced activation of PVN-RVLM neurons may contribute to the altered responses to

  9. The interplay of microRNA and neuronal activity in health and disease

    PubMed Central

    Eacker, Stephen M.; Dawson, Ted M.; Dawson, Valina L.

    2013-01-01

    MicroRNAs (miRNAs) are small 19–23 nucleotide regulatory RNAs that function by modulating mRNA translation and/or turnover in a sequence-specific fashion. In the nervous system, miRNAs regulate the production of numerous proteins involved in synaptic transmission. In turn, neuronal activity can regulate the production and turnover of miRNA through a variety of mechanisms. In this way, miRNAs and neuronal activity are in a reciprocal homeostatic relationship that balances neuronal function. The miRNA function is critical in pathological states related to overexcitation such as epilepsy and stroke, suggesting miRNA’s potential as a therapeutic target. We review the current literature relating the interplay of miRNA and neuronal activity and provide future directions for defining miRNA’s role in disease. PMID:23986658

  10. A calcium-permeable cGMP-activated cation conductance in hippocampal neurons

    NASA Technical Reports Server (NTRS)

    Leinders-Zufall, T.; Rosenboom, H.; Barnstable, C. J.; Shepherd, G. M.; Zufall, F.

    1995-01-01

    Whole-cell patch clamp recordings detected a previously unidentified cGMP-activated membrane conductance in cultured rat hippocampal neurons. This conductance is nonselectively permeable for cations and is completely but reversibly blocked by external Cd2+. The Ca2+ permeability of the hippocampal cGMP-activated conductance was examined in detail, indicating that the underlying ion channels display a high relative permeability for Ca2+. The results indicate that hippocampal neurons contain a cGMP-activated membrane conductance that has some properties similar to the cyclic nucleotide-gated channels previously shown in sensory receptor cells and retinal neurons. In hippocampal neurons this conductance similarly could mediate membrane depolarization and Ca2+ fluxes in response to intracellular cGMP elevation.

  11. Axial levodopa-induced dyskinesias and neuronal activity in the dorsal striatum.

    PubMed

    Alberico, Stephanie L; Kim, Young-Cho; Lence, Tomas; Narayanan, Nandakumar S

    2017-02-20

    Levodopa-induced dyskinesias are abnormal involuntary movements that limit the effectiveness of treatments for Parkinson's disease. Although dyskinesias involve the striatum, it is unclear how striatal neurons are involved in dyskinetic movements. Here we record from striatal neurons in mice during levodopa-induced axial dyskinesias. We developed an automated 3-dimensional motion tracking system to capture the development of axial dyskinesias at ∼10ms resolution, and correlated these movements with neuronal activity of striatal medium spiny neurons and fast-spiking interneurons. The average firing rate of medium spiny neurons increased as axial dyskinesias developed, and both medium spiny neurons and fast-spiking interneurons were modulated around axial dyskinesias. We also found that delta field potential power increased in the striatum with dyskinesia, and that this increased delta power coupled with striatal neurons. Our findings provide insight into how striatal networks change as levodopa-induced dyskinesias develop, and suggest that increased medium spiny neuron firing, increased delta field potential power, and abnormal delta-coupling may be neurophysiological signatures of dyskinesias. These data could be helpful in understanding the role of the striatum in the pathogenesis of dyskinesias in Parkinson's disease.

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

    PubMed

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

    2017-02-15

    Homeostatic control of breathing, heart rate, and body temperature relies on circuits within the brainstem modulated by the neurotransmitter serotonin (5-HT). Mounting evidence points to specialized neuronal subtypes within the serotonergic neuronal system, borne out in functional studies, for the modulation of distinct facets of homeostasis. Such functional differences, read out at the organismal level, are likely subserved by differences among 5-HT neuron subtypes at the cellular and molecular levels, including differences in the capacity to coexpress other neurotransmitters such as glutamate, GABA, thyrotropin releasing hormone, and substance P encoded by the Tachykinin-1 (Tac1) gene. Here, we characterize in mice a 5-HT neuron subtype identified by expression of Tac1 and the serotonergic transcription factor gene Pet1, referred to as the Tac1-Pet1 neuron subtype. Transgenic cell labeling showed Tac1-Pet1 soma resident largely in the caudal medulla. Chemogenetic [clozapine-N-oxide (CNO)-hM4Di] perturbation of Tac1-Pet1 neuron activity blunted the ventilatory response of the respiratory CO2 chemoreflex, which normally augments ventilation in response to hypercapnic acidosis to restore normal pH and PCO2Tac1-Pet1 axonal boutons were found localized to brainstem areas implicated in respiratory modulation, with highest density in motor regions. These findings demonstrate that the activity of a Pet1 neuron subtype with the potential to release both 5-HT and substance P is necessary for normal respiratory dynamics, perhaps via motor outputs that engage muscles of respiration and maintain airway patency. These Tac1-Pet1 neurons may act downstream of Egr2-Pet1 serotonergic neurons, which were previously established in respiratory chemoreception, but do not innervate respiratory motor nuclei.SIGNIFICANCE STATEMENT Serotonin (5-HT) neurons modulate physiological processes and behaviors as diverse as body temperature, respiration, aggression, and mood. Using genetic tools

  13. Correlated activity of cortical neurons survives extensive removal of feedforward sensory input

    PubMed Central

    Shapcott, Katharine A.; Schmiedt, Joscha T.; Saunders, Richard C.; Maier, Alexander; Leopold, David A.; Schmid, Michael C.

    2016-01-01

    A fundamental property of brain function is that the spiking activity of cortical neurons is variable and that some of this variability is correlated between neurons. Correlated activity not due to the stimulus arises from shared input but the neuronal circuit mechanisms that result in these noise correlations are not fully understood. Here we tested in the visual system if correlated variability in mid-level area V4 of visual cortex is altered following extensive lesions of primary visual cortex (V1). To this end we recorded longitudinally the neuronal correlations in area V4 of two behaving macaque monkeys before and after a V1 lesion while the monkeys fixated a grey screen. We found that the correlations of neuronal activity survived the lesions in both monkeys. In one monkey, the correlation of multi-unit spiking signals was strongly increased in the first week post-lesion, while in the second monkey, correlated activity was slightly increased, but not greater than some week-by-week fluctuations observed. The typical drop-off of inter-neuronal correlations with cortical distance was preserved after the lesion. Therefore, as V4 noise correlations remain without feedforward input from V1, these results suggest instead that local and/or feedback input seem to be necessary for correlated activity. PMID:27721468

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

    PubMed Central

    Peng, Yaqin; Liu, Jiane; Miao, Fengqin; Zhang, Jianqiong

    2015-01-01

    MHC class I (MHC-I) molecules are important components of the immune system. Recently MHC-I have been reported to also play important roles in brain development and synaptic plasticity. In this study, we examine the molecular mechanism(s) underlying activity-dependent MHC-I expression using hippocampal neurons. Here we report that neuronal expression level of MHC-I is dynamically regulated during hippocampal development after birth in vivo. Kainic acid (KA) treatment significantly increases the expression of MHC-I in cultured hippocampal neurons in vitro, suggesting that MHC-I expression is regulated by neuronal activity. In addition, KA stimulation decreased the expression of pre- and post-synaptic proteins. This down-regulation is prevented by addition of an MHC-I antibody to KA treated neurons. Further studies demonstrate that calcium-dependent protein kinase C (PKC) is important in relaying KA simulation activation signals to up-regulated MHC-I expression. This signaling cascade relies on activation of the MAPK pathway, which leads to increased phosphorylation of CREB and NF-κB p65 while also enhancing the expression of IRF-1. Together, these results suggest that expression of MHC-I in hippocampal neurons is driven by Ca2+ regulated activation of the MAPK signaling transduction cascade. PMID:26263390

  15. Predicting the activity phase of a follower neuron with A-current in an inhibitory network.

    PubMed

    Zhang, Yu; Bose, Amitabha; Nadim, Farzan

    2008-09-01

    The transient potassium A-current is present in most neurons and plays an important role in determining the timing of action potentials. We examine the role of the A-current in the activity phase of a follower neuron in a rhythmic feed-forward inhibitory network with a reduced three-variable model and conduct experiments to verify the usefulness of our model. Using geometric analysis of dynamical systems, we explore the factors that determine the onset of activity in a follower neuron following release from inhibition. We first analyze the behavior of the follower neuron in a single cycle and find that the phase plane structure of the model can be used to predict the potential behaviors of the follower neuron following release from inhibition. We show that, depending on the relative scales of the inactivation time constant of the A-current and the time constant of the recovery variable, the follower neuron may or may not reach its active state following inhibition. Our simple model is used to derive a recursive set of equations to predict the contribution of the A-current parameters in determining the activity phase of a follower neuron as a function of the duration and frequency of the inhibitory input it receives. These equations can be used to demonstrate the dependence of activity phase on the period and duty cycle of the periodic inhibition, as seen by comparing the predictions of the model with the activity of the pyloric constrictor (PY) neurons in the crustacean pyloric network.

  16. Microglia activation and interaction with neuronal cells in a biochemical model of mevalonate kinase deficiency.

    PubMed

    Tricarico, Paola Maura; Piscianz, Elisa; Monasta, Lorenzo; Kleiner, Giulio; Crovella, Sergio; Marcuzzi, Annalisa

    2015-08-01

    Mevalonate kinase deficiency is a rare disease whose worst manifestation, characterised by severe neurologic impairment, is called mevalonic aciduria. The progressive neuronal loss associated to cell death can be studied in vitro with a simplified model based on a biochemical block of the mevalonate pathway and a subsequent inflammatory trigger. The aim of this study was to evaluate the effect of the mevalonate blocking on glial cells (BV-2) and the following effects on neuronal cells (SH-SY5Y) when the two populations were cultured together. To better understand the cross-talk between glial and neuronal cells, as it happens in vivo, BV-2 and SH-SY5Y were co-cultured in different experimental settings (alone, transwell, direct contact); the effect of mevalonate pathway biochemical block by Lovastatin, followed by LPS inflammatory trigger, were evaluated by analysing programmed cell death and mitochondrial membrane potential, cytokines' release and cells' morphology modifications. In this experimental condition, glial cells underwent an evident activation, confirmed by elevated pro-inflammatory cytokines release, typical of these disorders, and a modification in morphology. Moreover, the activation induced an increase in apoptosis. When glial cells were co-cultured with neurons, their activation caused an increase of programmed cell death also in neuronal cells, but only if the two populations were cultured in direct contact. Our findings, being aware of the limitations related to the cell models used, represent a preliminary step towards understanding the pathological and neuroinflammatory mechanisms occurring in mevalonate kinase diseases. Contact co-culture between neuronal and microglial cells seems to be a good model to study mevalonic aciduria in vitro, and to contribute to the identification of potential drugs able to block microglial activation for this orphan disease. In fact, in such a pathological condition, we demonstrated that microglial cells are

  17. Neuroligin-1 Knockdown Suppresses Seizure Activity by Regulating Neuronal Hyperexcitability.

    PubMed

    Fang, Min; Wei, Jin-Lai; Tang, Bo; Liu, Jing; Chen, Ling; Tang, Zhao-Hua; Luo, Jing; Chen, Guo-Jun; Wang, Xue-Feng

    2016-01-01

    Abnormally synchronized synaptic transmission in the brain leads to epilepsy. Neuroligin-1 (NL1) is a synaptic cell adhesion molecule localized at excitatory synapses. NL1 modulates synaptic transmission and determines the properties of neuronal networks in the mammalian central nervous system. We showed that the expression of NL1 and its binding partner neurexin-1β was increased in temporal lobe epileptic foci in patients and lithium-pilocarpine-treated epileptic rats. We investigated electrophysiological and behavioral changes in epileptic rats after lentivirally mediated NL1 knockdown in the hippocampus to determine whether NL1 suppression prevented seizures and, if so, to explore the probable underlying mechanisms. Our behavioral studies revealed that NL1 knockdown in epileptic rats reduced seizure severity and increased seizure latency. Whole-cell patch-clamp recordings of CA1 pyramidal neurons in hippocampal slices from NL1 knockdown epileptic rats revealed a decrease in spontaneous action potential frequency and a decrease in miniature excitatory postsynaptic current (mEPSC) frequency but not amplitude. The amplitude of N-methyl-D-aspartate receptor (NMDAR)-dependent EPSCs was also selectively decreased. Notably, NL1 knockdown reduced total NMDAR1 expression and the surface/total ratio in the hippocampus of epileptic rats. Taken together, these data indicate that NL1 knockdown in epileptic rats may reduce the frequency and severity of seizures and suppress neuronal hyperexcitability via changes in postsynaptic NMDARs.

  18. Rod-shaped nanocrystals elicit neuronal activity in vivo.

    PubMed

    Malvindi, Maria Ada; Carbone, Luigi; Quarta, Alessandra; Tino, Angela; Manna, Liberato; Pellegrino, Teresa; Tortiglione, Claudia

    2008-10-01

    The development of novel nanomaterials has raised great interest in efforts to evaluate their effect on biological systems, ranging from single cells to whole animals. In particular, there exists an open question regarding whether nanoparticles per se can elicit biological responses, which could interfere with the phenomena they are intended to measure. Here it is reported that challenging the small cnidaria Hydra vulgaris in vivo with rod-shaped semiconductor nanoparticles, also known as quantum rods (QRs), results in an unexpected tentacle-writhing behavior, which is Ca(2+) dependent and relies on the presence of tentacle neurons. Due to the absence of surface functionalization of the QRs with specific ligands, and considering that spherical nanoparticles with same composition as the QRs fail to induce any in vivo behavior on the same experimental model, it is suggested that unique shape-tunable electrical properties of the QRs may account for the neuronal stimulation. This model system may represent a widely applicable tool for screening neuronal response to nanoparticles in vivo.

  19. Sulfated cholecystokinin-8 activates phospho-mTOR immunoreactive neurons of the paraventricular nucleus in rats

    PubMed Central

    Frommelt, Lisa; Inhoff, Tobias; Lommel, Reinhardt; Stengel, Andreas; Taché, Yvette; Grötzinger, Carsten; Bannert, Norbert; Wiedenmann, Bertram; Klapp, Burghard F.; Kobelt, Peter

    2014-01-01

    The serin/threonin-kinase, mammalian target of rapamycin (mTOR) was detected in the arcuate nucleus (ARC) and paraventricular nucleus of the hypothalamus (PVN) and suggested to play a role in the integration of satiety signals. Since cholecystokinin (CCK) plays a role in the short-term inhibition of food intake and induces c-Fos in PVN neurons, the aim was to determine whether intraperitoneally injected CCK-8S affects the neuronal activity in cells immunoreactive for phospho-mTOR in the PVN. Ad libitum fed male Sprague-Dawley rats received 6 or 10 μg/kg CCK-8S or 0.15 M NaCl ip (n=4/group). The number of c-Fosimmunoreactive (ir) neurons was assessed in the PVN, ARC and in the nucleus of the solitary tract (NTS). CCK-8S increased the number of c-Fos-ir neurons in the PVN (6 μg: 103 ± 13 vs. 10 μg: 165 ± 14 neurons/section; p<0.05) compared to vehicle treated rats (4 ± 1, p<0.05), but not in the ARC. CCK-8S also dose-dependently increased the number of c-Fos neurons in the NTS. Staining for phospho-mTOR and c-Fos in the PVN showed a dose-dependent increase of activated phospho-mTOR neurons (17 ± 3 vs. 38 ± 2 neurons/section; p<0.05), while no activated phospho-mTOR neurons were observed in the vehicle group. Triple staining in the PVN showed activation of phospho-mTOR neurons co-localized with oxytocin, corresponding to 9.8 ± 3.6% and 19.5 ± 3.3% of oxytocin neurons respectively. Our observations indicate that peripheral CCK-8S activates phospho-mTOR neurons in the PVN and suggest that phospho-mTOR plays a role in the mediation of CCK-8S's anorexigenic effects. PMID:20933028

  20. Persistent Neuronal Activity in Anterior Cingulate Cortex Correlates with Sustained Attention in Rats Regardless of Sensory Modality

    PubMed Central

    Wu, Dingcheng; Deng, Hanfei; Xiao, Xiong; Zuo, Yanfang; Sun, Jingjing; Wang, Zuoren

    2017-01-01

    The anterior cingulate cortex (ACC) has long been thought to regulate conflict between an object of attention and distractors during goal-directed sustained attention. However, it is unclear whether ACC serves to sustained attention itself. Here, we developed a task in which the time course of sustained attention could be controlled in rats. Then, using pharmacological lesion experiments, we employed it to assess function of ACC in sustained attention. We then recorded neuronal activity in ACC using multichannel extracellular recording techniques and identified specific ACC neurons persistently activated during the period of attention. Further experiments showed that target modality had minimal influence on the neuronal activity, and distracting external sensory input during the attention period did not perturb persistent neuronal activity. Additionally, minimal trial-to-trial variability in neuronal activity observed during sustained attention supports a role for ACC neurons in that behavior. Therefore, we conclude that the ACC neuronal activity correlates with sustained attention. PMID:28230158

  1. Optical imaging of neuronal activity in tissue labeled by retrograde transport of Calcium Green Dextran.

    PubMed

    McPherson, D R; McClellan, A D; O'Donovan, M J

    1997-05-01

    In many neurophysiological studies it is desirable to simultaneously record the activity of a large number of neurons. This is particularly true in the study of vertebrate motor systems that generate rhythmic behaviors, such as the pattern generator for locomotion in vertebrate spinal cord. Optical imaging of neurons labeled with appropriate fluorescent dyes, in which fluorescence is activity-dependent, provides a means to record the activity of many neurons at the same time, while also providing fine spatial resolution of the position and morphology of active neurons. Voltage-sensitive dyes have been explored for this purpose and have the advantage of rapid response to transmembrane voltage changes. However, voltage-sensitive dyes bleach readily, which results in phototoxic damage and limits the time that labeled neurons can be imaged. In addition, the signal-to-noise ratio is typically small, so that averaging of responses is usually required. As an alternative to voltage-sensitive dyes, calcium-sensitive dyes can exhibit large changes in fluorescence. Most neurons contain voltage-sensitive Ca2+ channels, and numerous reports indicate that neuronal activity is accompanied by increased intracellular Ca2+ concentration. In this protocol we describe a method to use retrograde transport of the dextran conjugate of a calcium-sensitive dye (Calcium Green Dextran) to label selectively populations of brain and spinal interneurons in a primitive vertebrate (lamprey), for subsequent video-rate imaging of changes in intracellular fluorescence during neuronal activity. Although described with specific reference to lampreys, the technique has also been applied to embryonic chick spinal cord and larval zebrafish preparations and should be easily adaptable to other systems. The most significant novel feature of the protocol is the use of retrograde axonal transport to selectively fill neurons that have known axonal trajectories. Using lampreys, we have obtained activity

  2. Activity of the rat pontomedullary reticular neurons related to rhythmical jaw movements.

    PubMed

    Ohta, M; Sasamoto, K; Kishikawa, N; Kuraoka, N

    1999-11-01

    Electrical stimulation of the cerebral peduncle or oral mechanical or chemical stimulation induced rhythmical jaw movements (RJM) in the anesthetized rat. Extracellular recording was made from the pontomedullary reticular neurons in relation to RJM. The RJM-related activity was classified to a tonic, a transient and a phase-dependent rhythmical activities (116, 92 and 45 neurons, respectively). We found that the neurons showing the phase-dependent activities discharged exclusively or almost exclusively during RJM without responding to at least one of three kinds of RJM-inducing stimulation. Fourteen neurons were activated by all kinds of RJM-inducing stimulation and majority of them showed weak or no change in activity during RJM, although some showed the transient or the rhythmical activity during RJM. We propose that the phase-dependent rhythmical activity is necessary to generate RJM since any stimulation-induced RJM was reversibly blocked by microinjection of lidocaine or glutamate receptor blocking agents into the brainstem site concentrated by this type of neurons. No other type of activity was observed exclusively during RJM.

  3. NMDA Receptors Enhance Spontaneous Activity and Promote Neuronal Survival in the Developing Cochlea

    PubMed Central

    Zhang-Hooks, YingXin; Agarwal, Amit; Mishina, Masayoshi; Bergles, Dwight E.

    2016-01-01

    Summary Spontaneous bursts of activity in developing sensory pathways promote maturation of neurons, refinement of neuronal connections and assembly of appropriate functional networks. In the developing auditory system, inner hair cells (IHCs) spontaneously fire Ca2+ spikes, each of which is transformed into a mini-burst of action potentials in spiral ganglion neurons (SGNs). Here we show that NMDARs are expressed in SGN dendritic terminals and play a critical role during transmission of activity from IHCs to SGNs before hearing onset. NMDAR activation enhances glutamate-mediated Ca2+ influx at dendritic terminals, promotes repetitive firing of individual SGNs in response to each synaptic event, and enhances coincident activity of neighboring SGNs that will eventually encode similar frequencies of sound. Loss of NMDAR signaling from SGNs reduced their survival both in vivo and in vitro, revealing that spontaneous activity in the prehearing cochlea promotes maturation of auditory circuitry through periodic activation of NMDARs in SGNs. PMID:26774161

  4. Neuronal activity in the parietal cortex of EL and DDY mice.

    PubMed

    Suzuki, Jiro; Ozawa, Nobuyuki; Murashima, Yoshiya L; Shinba, Tosikazu; Yoshii, Mitsunobu

    2012-06-15

    To elucidate the mechanism of epileptogenesis, seizures were investigated in the EL mouse, which is an excellent model for epilepsy. In these mice, epileptic seizures initiate in the parietal cortex, where markers of GABA-mediated inhibition are reduced compared with the parietal cortex of DDY mice (the parent strain). This is the first report on units of neuronal activity in the parietal cortex of EL and DDY mice (14 each) using an extracellular microelectrode in vivo under moderate pentobarbital anesthesia. The parietal cortex neurons of the EL mice were less active at rest than those of the DDY mice, but they responded more actively to proprioceptive afferent input from muscle stimulation than the DDY neurons. Three types of spontaneous firing were classified in both EL and DDY cortical neurons: periodically firing, Type A; continuously firing, Type B; and random firing, Type C. The proportions of these three types of neurons were almost the same in the EL mice as in the DDY mice. The peak frequency of the periodical cycle of Type A neurons in the EL mice (375 ms) was longer than that of the Type A neurons in the DDY mice (225 ms). Four patterns of responses to stimulation were observed in the parietal cortex neurons. More excitatory patterns were observed in the EL mice than in the DDY mice. The trans-laminar distribution of cells with different response patterns was also different between the EL and DDY mice. These characteristics of parietal cortex neurons may help determine the seizure susceptibility or ictogenesis in EL mice because the mechanisms underlying these patterns could provide the basis for hypersynchronized discharges in epileptic seizures.

  5. Activity of somatosensory-responsive neurons in high subdivisions of SI cortex during locomotion.

    PubMed

    Favorov, Oleg V; Nilaweera, Wijitha U; Miasnikov, Alexandre A; Beloozerova, Irina N

    2015-05-20

    Responses of neurons in the primary somatosensory cortex during movements are poorly understood, even during such simple tasks as walking on a flat surface. In this study, we analyzed spike discharges of neurons in the rostral bank of the ansate sulcus (areas 1-2) in 2 cats while the cats walked on a flat surface or on a horizontal ladder, a complex task requiring accurate stepping. All neurons (n = 82) that had receptive fields (RFs) on the contralateral forelimb exhibited frequency modulation of their activity that was phase locked to the stride cycle during simple locomotion. Neurons with proximal RFs (upper arm/shoulder) and pyramidal tract-projecting neurons (PTNs) with fast-conducting axons tended to fire at peak rates in the middle of the swing phase, whereas neurons with RFs on the distal limb (wrist/paw) and slow-conducting PTNs typically showed peak firing at the transition between swing and stance phases. Eleven of 12 neurons with tactile RFs on the volar forepaw began firing toward the end of swing, with peak activity occurring at the moment of foot contact with floor, thereby preceding the evoked sensory volley from touch receptors. Requirement to step accurately on the ladder affected 91% of the neurons, suggesting their involvement in control of accuracy of stepping. During both tasks, neurons exhibited a wide variety of spike distributions within the stride cycle, suggesting that, during either simple or ladder locomotion, they represent the cycling somatosensory events in their activity both predictively before and reflectively after these events take place.

  6. Activity of Somatosensory-Responsive Neurons in High Subdivisions of SI Cortex during Locomotion

    PubMed Central

    Favorov, Oleg V.; Nilaweera, Wijitha U.; Miasnikov, Alexandre A.

    2015-01-01

    Responses of neurons in the primary somatosensory cortex during movements are poorly understood, even during such simple tasks as walking on a flat surface. In this study, we analyzed spike discharges of neurons in the rostral bank of the ansate sulcus (areas 1–2) in 2 cats while the cats walked on a flat surface or on a horizontal ladder, a complex task requiring accurate stepping. All neurons (n = 82) that had receptive fields (RFs) on the contralateral forelimb exhibited frequency modulation of their activity that was phase locked to the stride cycle during simple locomotion. Neurons with proximal RFs (upper arm/shoulder) and pyramidal tract-projecting neurons (PTNs) with fast-conducting axons tended to fire at peak rates in the middle of the swing phase, whereas neurons with RFs on the distal limb (wrist/paw) and slow-conducting PTNs typically showed peak firing at the transition between swing and stance phases. Eleven of 12 neurons with tactile RFs on the volar forepaw began firing toward the end of swing, with peak activity occurring at the moment of foot contact with floor, thereby preceding the evoked sensory volley from touch receptors. Requirement to step accurately on the ladder affected 91% of the neurons, suggesting their involvement in control of accuracy of stepping. During both tasks, neurons exhibited a wide variety of spike distributions within the stride cycle, suggesting that, during either simple or ladder locomotion, they represent the cycling somatosensory events in their activity both predictively before and reflectively after these events take place. PMID:25995465

  7. Behavior‐dependent activity patterns of GABAergic long‐range projecting neurons in the rat hippocampus

    PubMed Central

    Micklem, Ben; Borhegyi, Zsolt; Swiejkowski, Daniel A.; Valenti, Ornella; Viney, Tim J.; Kotzadimitriou, Dimitrios; Klausberger, Thomas

    2017-01-01

    ABSTRACT Long‐range glutamatergic and GABAergic projections participate in temporal coordination of neuronal activity in distributed cortical areas. In the hippocampus, GABAergic neurons project to the medial septum and retrohippocampal areas. Many GABAergic projection cells express somatostatin (SOM+) and, together with locally terminating SOM+ bistratified and O‐LM cells, contribute to dendritic inhibition of pyramidal cells. We tested the hypothesis that diversity in SOM+ cells reflects temporal specialization during behavior using extracellular single cell recording and juxtacellular neurobiotin‐labeling in freely moving rats. We have demonstrated that rare GABAergic projection neurons discharge rhythmically and are remarkably diverse. During sharp wave‐ripples, most projection cells, including a novel SOM+ GABAergic back‐projecting cell, increased their activity similar to bistratified cells, but unlike O‐LM cells. During movement, most projection cells discharged along the descending slope of theta cycles, but some fired at the trough jointly with bistratified and O‐LM cells. The specialization of hippocampal SOM+ projection neurons complements the action of local interneurons in differentially phasing inputs from the CA3 area to CA1 pyramidal cell dendrites during sleep and wakefulness. Our observations suggest that GABAergic projection cells mediate the behavior‐ and network state‐dependent binding of neuronal assemblies amongst functionally‐related brain regions by transmitting local rhythmic entrainment of neurons in CA1 to neuronal populations in other areas. © 2016 The Authors Hippocampus Published by Wiley Periodicals, Inc. PMID:27997999

  8. Suppression of Sin3A activity promotes differentiation of pluripotent cells into functional neurons

    PubMed Central

    Halder, Debasish; Lee, Chang-Hee; Hyun, Ji Young; Chang, Gyeong-Eon; Cheong, Eunji; Shin, Injae

    2017-01-01

    Sin3 is a transcriptional corepressor for REST silencing machinery that represses multiple neuronal genes in non-neuronal cells. However, functions of Sin3 (Sin3A and Sin3B) in suppression of neuronal phenotypes are not well characterized. Herein we show that Sin3A knockdown impedes the repressive activity of REST and enhances differentiation of pluripotent P19 cells into electrophysiologically active neurons without inducing astrogenesis. It is also found that silencing Sin3B induces neurogenesis of P19 cells with a lower efficiency than Sin3A knockdown. The results suggest that Sin3A has a more profound effect on REST repressive machinery for silencing neuronal genes in P19 cells than Sin3B. Furthermore, we show that a peptide inhibitor of Sin3A-REST interactions promotes differentiation of P19 cells into functional neurons. Observations made in studies using genetic deletion and a synthetic inhibitor suggests that Sin3A plays an important role in the repression of neuronal genes by the REST regulatory mechanism. PMID:28303954

  9. Genome-wide identification of neuronal activity-regulated genes in Drosophila

    PubMed Central

    Chen, Xiao; Rahman, Reazur; Guo, Fang; Rosbash, Michael

    2016-01-01

    Activity-regulated genes (ARGs) are important for neuronal functions like long-term memory and are well-characterized in mammals but poorly studied in other model organisms like Drosophila. Here we stimulated fly neurons with different paradigms and identified ARGs using high-throughput sequencing from brains as well as from sorted neurons: they included a narrow set of circadian neurons as well as dopaminergic neurons. Surprisingly, many ARGs are specific to the stimulation paradigm and very specific to neuron type. In addition and unlike mammalian immediate early genes (IEGs), fly ARGs do not have short gene lengths and are less enriched for transcription factor function. Chromatin assays using ATAC-sequencing show that the transcription start sites (TSS) of ARGs do not change with neural firing but are already accessible prior to stimulation. Lastly based on binding site enrichment in ARGs, we identified transcription factor mediators of firing and created neuronal activity reporters. DOI: http://dx.doi.org/10.7554/eLife.19942.001 PMID:27936378

  10. Modeling spiking activity of in vitro neuronal networks through non linear methods.

    PubMed

    Maffezzoli, A; Signorini, M G; Gullo, F; Wanke, E

    2008-01-01

    Neuroscience research is even more exploiting technologies developed for electronic engineering use: this is the case of Micro-Electrode Array (MEA) technology, an instrumentation which is able to acquire in vitro neuron spiking activity from a finite number of channels. In this work we present three models of synaptic neuronal network connections, called 'Full-Connected', 'Hierarchical' and 'Closed-Path'. Related to each one we implemented an index giving quantitative measures of similarity and of statistical dependence among neuron activities recorded in different MEA channels. They are based on Information Theory techniques as Mutual and Multi Information: the last one extending the pair-wise information to higher-order connections on the entire MEA neuronal network. We calculated indexes for each model in order to test the presence of self-synchronization among neurons evolving in time, in response to external stimuli such as the application of chemical neuron-inhibitors. The availability of such different models helps us to investigate also how much the synaptic connections are spatially sparse or hierarchically structured and finally how much of the information exchanged on the neuronal network is regulated by higher-order correlations.

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

    PubMed Central

    Wirsig-Wiechmann, Celeste R; Houck, Lynne D; Wood, Jessica M; Feldhoff, Pamela W; Feldhoff, Richard C

    2006-01-01

    Background The mental gland pheromone of male Plethodon salamanders contains two main protein components: a 22 kDa protein named Plethodon Receptivity Factor (PRF) and a 7 kDa protein named Plethodon Modulating Factor (PMF), respectively. Each protein component individually has opposing effects on female courtship behavior, with PRF shortening and PMF lengthening courtship. In this study, we test the hypothesis that PRF or PMF individually activate vomeronasal neurons. The agmatine-uptake technique was used to visualize chemosensory neurons that were activated by each protein component individually. Results Vomeronasal neurons exposed to agmatine in saline did not demonstrate significant labeling. However, a population of vomeronasal neurons was labeled following exposure to either PRF or PMF. When expressed as a percent of control level labeled cells, PRF labeled more neurons than did PMF. These percentages for PRF and PMF, added together, parallel the percentage of labeled vomeronasal neurons when females are exposed to the whole pheromone. Conclusion This study suggests that two specific populations of female vomeronasal neurons are responsible for responding to each of the two components of the male pheromone mixture. These two neural populations, therefore, could express different receptors which, in turn, transmit different information to the brain, thus accounting for the different female behavior elicited by each pheromone component. PMID:16553953

  12. Reexposure to nicotine during withdrawal increases the pacemaking activity of cholinergic habenular neurons

    PubMed Central

    Görlich, Andreas; Antolin-Fontes, Beatriz; Ables, Jessica L.; Frahm, Silke; Ślimak, Marta A.; Dougherty, Joseph D.; Ibañez-Tallon, Inés

    2013-01-01

    The discovery of genetic variants in the cholinergic receptor nicotinic CHRNA5-CHRNA3-CHRNB4 gene cluster associated with heavy smoking and higher relapse risk has led to the identification of the midbrain habenula–interpeduncular axis as a critical relay circuit in the control of nicotine dependence. Although clear roles for α3, β4, and α5 receptors in nicotine aversion and withdrawal have been established, the cellular and molecular mechanisms that participate in signaling nicotine use and contribute to relapse have not been identified. Here, using translating ribosome affinity purification (TRAP) profiling, electrophysiology, and behavior, we demonstrate that cholinergic neurons, but not peptidergic neurons, of the medial habenula (MHb) display spontaneous tonic firing of 2–10 Hz generated by hyperpolarization-activated cyclic nucleotide-gated (HCN) pacemaker channels and that infusion of the HCN pacemaker antagonist ZD7288 in the habenula precipitates somatic and affective signs of withdrawal. Further, we show that a strong, α3β4-dependent increase in firing frequency is observed in these pacemaker neurons upon acute exposure to nicotine. No change in the basal or nicotine-induced firing was observed in cholinergic MHb neurons from mice chronically treated with nicotine. We observe, however, that, during withdrawal, reexposure to nicotine doubles the frequency of pacemaking activity in these neurons. These findings demonstrate that the pacemaking mechanism of cholinergic MHb neurons controls withdrawal, suggesting that the heightened nicotine sensitivity of these neurons during withdrawal may contribute to smoking relapse. PMID:24082085

  13. MeCP2 regulates activity-dependent transcriptional responses in olfactory sensory neurons

    PubMed Central

    Lee, Wooje; Yun, Jung-Mi; Woods, Rima; Dunaway, Keith; Yasui, Dag H.; Lasalle, Janine M.; Gong, Qizhi

    2014-01-01

    During postnatal development, neuronal activity controls the remodeling of initially imprecise neuronal connections through the regulation of gene expression. MeCP2 binds to methylated DNA and modulates gene expression during neuronal development and MECP2 mutation causes the autistic disorder Rett syndrome. To investigate a role for MeCP2 in neuronal circuit refinement and to identify activity-dependent MeCP2 transcription regulations, we leveraged the precise organization and accessibility of olfactory sensory axons to manipulation of neuronal activity through odorant exposure in vivo. We demonstrate that olfactory sensory axons failed to develop complete convergence when Mecp2 is deficient in olfactory sensory neurons (OSNs) in an otherwise wild-type animal. Furthermore, we demonstrate that expression of selected adhesion genes was elevated in Mecp2-deficient glomeruli, while acute odor stimulation in control mice resulted in significantly reduced MeCP2 binding to these gene loci, correlating with increased expression. Thus, MeCP2 is required for both circuitry refinement and activity-dependent transcriptional responses in OSNs. PMID:25008110

  14. Selective Gating of Neuronal Activity by Intrinsic Properties in Distinct Motor Rhythms

    PubMed Central

    2015-01-01

    Many neural circuits show fast reconfiguration following altered sensory or modulatory inputs to generate stereotyped outputs. In the motor circuit of Xenopus tadpoles, I study how certain voltage-dependent ionic currents affect firing thresholds and contribute to circuit reconfiguration to generate two distinct motor patterns, swimming and struggling. Firing thresholds of excitatory interneurons [i.e., descending interneurons (dINs)] in the swimming central pattern generator are raised by depolarization due to the inactivation of Na+ currents. In contrast, the thresholds of other types of neurons active in swimming or struggling are raised by hyperpolarization from the activation of fast transient K+ currents. The firing thresholds are then compared with the excitatory synaptic drives, which are revealed by blocking action potentials intracellularly using QX314 during swimming and struggling. During swimming, transient K+ currents lower neuronal excitability and gate out neurons with weak excitation, whereas their inactivation by strong excitation in other neurons increases excitability and enables fast synaptic potentials to drive reliable firing. During struggling, continuous sensory inputs lead to high levels of network excitation. This allows the inactivation of Na+ currents and suppression of dIN activity while inactivating transient K+ currents, recruiting neurons that are not active in swimming. Therefore, differential expression of these currents between neuron types can explain why synaptic strength does not predict firing reliability/intensity during swimming and struggling. These data show that intrinsic properties can override fast synaptic potentials, mediate circuit reconfiguration, and contribute to motor–pattern switching. PMID:26156983

  15. Immunohistochemical visualization of hippocampal neuron activity after spatial learning in a mouse model of neurodevelopmental disorders.

    PubMed

    Provenzano, Giovanni; Pangrazzi, Luca; Poli, Andrea; Berardi, Nicoletta; Bozzi, Yuri

    2015-05-12

    Induction of phosphorylated extracellular-regulated kinase (pERK) is a reliable molecular readout of learning-dependent neuronal activation. Here, we describe a pERK immunohistochemistry protocol to study the profile of hippocampal neuron activation following exposure to a spatial learning task in a mouse model characterized by cognitive deficits of neurodevelopmental origin. Specifically, we used pERK immunostaining to study neuronal activation following Morris water maze (MWM, a classical hippocampal-dependent learning task) in Engrailed-2 knockout (En2(-/-)) mice, a model of autism spectrum disorders (ASD). As compared to wild-type (WT) controls, En2(-/-) mice showed significant spatial learning deficits in the MWM. After MWM, significant differences in the number of pERK-positive neurons were detected in specific hippocampal subfields of En2(-/-) mice, as compared to WT animals. Thus, our protocol can robustly detect differences in pERK-positive neurons associated to hippocampal-dependent learning impairment in a mouse model of ASD. More generally, our protocol can be applied to investigate the profile of hippocampal neuron activation in both genetic or pharmacological mouse models characterized by cognitive deficits.

  16. Activities and functions of peripheral neurons in the enteric nervous system of Aplysia and Lymnaea.

    PubMed

    Kurokawa, M; Ito, S; Okamoto, T

    2008-01-01

    In order to explore the functions of the peripheral neurons in the enteric nervous system (ENS) of the gastropods, Aplysia and Lymnaea, we investigated the correlation between peripheral neuronal activities and movements of the digestive tract. In Aplysia, movements of the gizzard were distinguished into two types of contraction: a large constriction of the whole gizzard following bursting activities of the neurons on the gizzard and EJP-like potentials in the musculature; and a small contraction of a restricted part of the gizzard following a slow muscle potential. When TTX was applied to isolated gizzard preparation, the bursting activities were blocked and the EJP-like potentials and the subsequent constriction disappeared, whereas the slow potentials in the musculature and partial contractions appeared to be unaffected. Therefore, it was suggested that the peripheral neurons on the gizzard were motor neurons for constriction, while the partial contraction was thought to be myogenic. In Lymnaea, we recorded periodic bursting activities in the enteric nervous system that were followed by EJP-like potentials and gastrointestinal movements. The results show that, in both species, there may exist motor neurons in the ENS that are responsible for neurogenic movements of the digestive tract.

  17. [Effect of nootropic agents on impulse activity of cerebral cortex neurons].

    PubMed

    Iasnetsov, V V; Pravdivtsev, V A; Krylova, I N; Kozlov, S B; Provornova, N A; Ivanov, Iu V; Iasnetsov, V V

    2001-01-01

    The effect of nootropes (semax, mexidol, and GVS-111) on the activity of individual neurons in various cerebral cortex regions was studied by microelectrode and microionophoresis techniques in cats immobilized by myorelaxants. It was established that the inhibiting effect of mexidol upon neurons in more than half of cases is prevented or significantly decreased by the GABA antagonists bicuculline and picrotoxin. The inhibiting effect of semax and GVS-111 upon neurons in more than half of cases is related to stimulation of the M-choline and NMDA receptors, respectively.

  18. Effect of active Aβ immunotherapy on neurons in human Alzheimer's disease.

    PubMed

    Paquet, Claire; Amin, Jay; Mouton-Liger, François; Nasser, Mariam; Love, Seth; Gray, Françoise; Pickering, Ruth M; Nicoll, James A R; Holmes, Clive; Hugon, Jacques; Boche, Delphine

    2015-04-01

    Amyloid β peptide (Aβ) immunization of Alzheimer's disease (AD) patients has been reported to induce amyloid plaque removal, but with little impact on cognitive decline. We have explored the consequences of Aβ immunotherapy on neurons in post mortem brain tissue. Eleven immunized (AN1792, Elan Pharmaceuticals) AD patients were compared to 28 non-immunized AD cases. Immunohistochemistry on sections of neocortex was performed for neuron-specific nuclear antigen (NeuN), neurofilament protein (NFP) and phosphorylated-(p)PKR (pro-apoptotic kinase detected in degenerating neurons). Quantification was performed for pPKR and status spongiosis (neuropil degeneration), NeuN-positive neurons/field, curvature of the neuronal processes and interneuronal distance. Data were corrected for age, gender, duration of dementia and APOE genotype and also assessed in relation to Aβ42 and tau pathology and key features of AD. In non-immunized patients, the degree of neuritic curvature correlated with spongiosis and pPKR, and overall the neurodegenerative markers correlated better with tau pathology than Aβ42 load. Following immunization, spongiosis increased, interneuronal distance increased, while the number of NeuN-positive neurons decreased, consistent with enhanced neuronal loss. However, neuritic curvature was reduced and pPKR was associated with Aβ removal in immunized patients. In AD, associations of spongiosis status, curvature ratio and pPKR load with microglial markers Iba1, CD68 and CD32 suggest a role for microglia in neurodegeneration. After immunization, correlations were detected between the number of NeuN-positive neurons and pPKR with Iba1, CD68 and CD64, suggesting that microglia are involved in the neuronal loss. Our findings suggest that in established AD this form of active Aβ immunization may predominantly accelerate loss of damaged degenerating neurons. This interpretation is consistent with in vivo imaging indicating an increased rate of cerebral atrophy in

  19. Neurally released pituitary adenylate cyclase-activating polypeptide enhances guinea pig intrinsic cardiac neurone excitability.

    PubMed

    Tompkins, John D; Ardell, Jeffrey L; Hoover, Donald B; Parsons, Rodney L

    2007-07-01

    Intracellular recordings were made in vitro from guinea-pig cardiac ganglia to determine whether endogenous neuropeptides such as pituitary adenylate cyclase-activating polypeptide (PACAP) or substance P released during tetanic neural stimulation modulate cardiac neurone excitability and/or contribute to slow excitatory postsynaptic potentials (sEPSPs). When nicotinic and muscarinic receptors were blocked by hexamethonium and atropine, 20 Hz stimulation for 10 s initiated a sEPSP in all innervated neurones. In 40% of the cells, excitability was enhanced after termination of the sEPSP. This suggested that non-cholinergic receptor-mediated mechanisms contributed to the sEPSP and modulated neuronal excitability. Exogenous PACAP and substance P initiated a slow depolarization in the neurones whereas neuronal excitability was only increased by PACAP. When ganglia were treated with the PAC1 antagonist PACAP6-38 (500 nM), the sEPSP evoked by 20 Hz stimulation was reduced by approximately 50% and an enhanced excitability occurred in only 10% of the cells. These observations suggested that PACAP released from preganglionic nerve terminals during tetanic stimulation enhanced neuronal excitability and evoked sEPSPs. After addition of 1 nM PACAP to the bath, 7 of 9 neurones exhibited a tonic firing pattern whereas in untreated preparations, the neurons had a phasic firing pattern. PACAP6-38 (500 nM) diminished the increase in excitability caused by 1 nM PACAP so that only 4 of 13 neurones exhibited a tonic firing pattern and the other 9 cells retained a phasic firing pattern. These findings indicate that PACAP can be released by tetanic neural stimulation in vitro and increase the excitability of intrinsic cardiac neurones. We hypothesize that in vivo PACAP released during preganglionic firing may modulate neurotransmission within the intrinsic cardiac ganglia.

  20. Miniature microscopes for large-scale imaging of neuronal activity in freely behaving rodents.

    PubMed

    Ziv, Yaniv; Ghosh, Kunal K

    2015-06-01

    Recording neuronal activity in behaving subjects has been instrumental in studying how information is represented and processed by the brain. Recent advances in optical imaging and bioengineering have converged to enable time-lapse, cell-type specific recordings of neuronal activities from large neuronal populations in deep-brain structures of freely behaving rodents. We will highlight these advancements, with an emphasis on miniaturized integrated microscopy for large-scale imaging in freely behaving mice. This technology potentially enables studies that were difficult to perform using previous generation imaging and current electrophysiological techniques. These studies include longitudinal and population-level analyses of neuronal representations associated with different types of naturalistic behaviors and cognitive or emotional processes.

  1. Optogenetic activation of cholinergic neurons in the PPT or LDT induces REM sleep.

    PubMed

    Van Dort, Christa J; Zachs, Daniel P; Kenny, Jonathan D; Zheng, Shu; Goldblum, Rebecca R; Gelwan, Noah A; Ramos, Daniel M; Nolan, Michael A; Wang, Karen; Weng, Feng-Ju; Lin, Yingxi; Wilson, Matthew A; Brown, Emery N

    2015-01-13

    Rapid eye movement (REM) sleep is an important component of the natural sleep/wake cycle, yet the mechanisms that regulate REM sleep remain incompletely understood. Cholinergic neurons in the mesopontine tegmentum have been implicated in REM sleep regulation, but lesions of this area have had varying effects on REM sleep. Therefore, this study aimed to clarify the role of cholinergic neurons in the pedunculopontine tegmentum (PPT) and laterodorsal tegmentum (LDT) in REM sleep generation. Selective optogenetic activation of cholinergic neurons in the PPT or LDT during non-REM (NREM) sleep increased the number of REM sleep episodes and did not change REM sleep episode duration. Activation of cholinergic neurons in the PPT or LDT during NREM sleep was sufficient to induce REM sleep.

  2. Microglia protect against brain injury and their selective elimination dysregulates neuronal network activity after stroke

    PubMed Central

    Szalay, Gergely; Martinecz, Bernadett; Lénárt, Nikolett; Környei, Zsuzsanna; Orsolits, Barbara; Judák, Linda; Császár, Eszter; Fekete, Rebeka; West, Brian L.; Katona, Gergely; Rózsa, Balázs; Dénes, Ádám

    2016-01-01

    Microglia are the main immune cells of the brain and contribute to common brain diseases. However, it is unclear how microglia influence neuronal activity and survival in the injured brain in vivo. Here we develop a precisely controlled model of brain injury induced by cerebral ischaemia combined with fast in vivo two-photon calcium imaging and selective microglial manipulation. We show that selective elimination of microglia leads to a striking, 60% increase in infarct size, which is reversed by microglial repopulation. Microglia-mediated protection includes reduction of excitotoxic injury, since an absence of microglia leads to dysregulated neuronal calcium responses, calcium overload and increased neuronal death. Furthermore, the incidence of spreading depolarization (SD) is markedly reduced in the absence of microglia. Thus, microglia are involved in changes in neuronal network activity and SD after brain injury in vivo that could have important implications for common brain diseases. PMID:27139776

  3. Circadian Rhythms in Rho1 Activity Regulate Neuronal Plasticity and Network Hierarchy.

    PubMed

    Petsakou, Afroditi; Sapsis, Themistoklis P; Blau, Justin

    2015-08-13

    Neuronal plasticity helps animals learn from their environment. However, it is challenging to link specific changes in defined neurons to altered behavior. Here, we focus on circadian rhythms in the structure of the principal s-LNv clock neurons in Drosophila. By quantifying neuronal architecture, we observed that s-LNv structural plasticity changes the amount of axonal material in addition to cycles of fasciculation and defasciculation. We found that this is controlled by rhythmic Rho1 activity that retracts s-LNv axonal termini by increasing myosin phosphorylation and simultaneously changes the balance of pre-synaptic and dendritic markers. This plasticity is required to change clock network hierarchy and allow seasonal adaptation. Rhythms in Rho1 activity are controlled by clock-regulated transcription of Puratrophin-1-like (Pura), a Rho1 GEF. Since spinocerebellar ataxia is associated with mutations in human Puratrophin-1, our data support the idea that defective actin-related plasticity underlies this ataxia.

  4. Dynamic regulation of midbrain dopamine neuron activity: intrinsic, synaptic, and plasticity mechanisms.

    PubMed

    Morikawa, H; Paladini, C A

    2011-12-15

    Although the roles of dopaminergic signaling in learning and behavior are well established, it is not fully understood how the activity of dopaminergic neurons is dynamically regulated under different conditions in a constantly changing environment. Dopamine neurons must integrate sensory, motor, and cognitive information online to inform the organism to pursue outcomes with the highest reward probability. In this article, we provide an overview of recent advances on the intrinsic, extrinsic (i.e., synaptic), and plasticity mechanisms controlling dopamine neuron activity, mostly focusing on mechanistic studies conducted using ex vivo brain slice preparations. We also hope to highlight some unresolved questions regarding information processing that takes place at dopamine neurons, thereby stimulating further investigations at different levels of analysis.

  5. Dynamic Regulation of Midbrain Dopamine Neuron Activity: Intrinsic, Synaptic, and Plasticity Mechanisms

    PubMed Central

    Morikawa, Hitoshi; Paladini, Carlos A.

    2011-01-01

    Although the roles of dopaminergic signaling in learning and behavior are well established, it is not fully understood how the activity of dopaminergic neurons is dynamically regulated under different conditions in a constantly changing environment. Dopamine neurons must integrate sensory, motor, and cognitive information online to inform the organism to pursue outcomes with the highest reward probability. In this article, we provide an overview of recent advances on the intrinsic, extrinsic (i.e., synaptic), and plasticity mechanisms controlling dopamine neuron activity, mostly focusing on mechanistic studies conducted using ex vivo brain slice preparations. We also hope to highlight some unresolved questions regarding information processing that takes place at dopamine neurons, thereby stimulating further investigations at different levels of analysis. PMID:21872647

  6. The Drosophila female aphrodisiac pheromone activates ppk23(+) sensory neurons to elicit male courtship behavior.

    PubMed

    Toda, Hirofumi; Zhao, Xiaoliang; Dickson, Barry J

    2012-06-28

    Females of many animal species emit chemical signals that attract and arouse males for mating. For example, the major aphrodisiac pheromone of Drosophila melanogaster females, 7,11-heptacosadiene (7,11-HD), is a potent inducer of male-specific courtship and copulatory behaviors. Here, we demonstrate that a set of gustatory sensory neurons on the male foreleg, defined by expression of the ppk23 marker, respond to 7,11-HD. Activity of these neurons is required for males to robustly court females or to court males perfumed with 7,11-HD. Artificial activation of these ppk23(+) neurons stimulates male-male courtship even without 7,11-HD perfuming. These data identify the ppk23(+) sensory neurons as the primary targets for female sex pheromones in Drosophila.

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

    PubMed

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

    2015-01-01

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

  8. Hippocampal cannabinoid transmission modulates dopamine neuron activity: impact on rewarding memory formation and social interaction.

    PubMed

    Loureiro, Michael; Renard, Justine; Zunder, Jordan; Laviolette, Steven R

    2015-05-01

    Disturbances in cannabinoid type 1 receptor (CB1R) signaling have been linked to emotional and cognitive deficits characterizing neuropsychiatric disorders, including schizophrenia. Thus, there is growing interest in characterizing the relationship between cannabinoid transmission, emotional processing, and dopamine (DA)-dependent behavioral deficits. The CB1R is highly expressed in the mammalian nervous system, particularly in the hippocampus. Activation of the ventral hippocampal subregion (vHipp) is known to increase both the activity of DAergic neurons located in the ventral tegmental area (VTA) and DA levels in reward-related brain regions, particularly the nucleus accumbens (NAc). However, the possible functional relationship between hippocampal CB1R transmission and VTA DA neuronal activity is not currently understood. In this study, using in vivo neuronal recordings in rats, we demonstrate that activation of CB1R in the vHipp strongly increases VTA DA neuronal firing and bursting activity, while simultaneously decreasing the activity of VTA non-DA neurons. Furthermore, using a conditioned place preference procedure and a social interaction test, we report that intra-vHipp CB1R activation potentiates the reward salience of normally sub-threshold conditioning doses of opiates and induces deficits in natural sociability and social recognition behaviors. Finally, these behavioral effects were prevented by directly blocking NAc DAergic transmission. Collectively, these findings identify hippocampal CB1R transmission as a critical modulator of the mesolimbic DA pathway and in the processing of reward and social-related behavioral phenomena.

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

    PubMed Central

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

    2015-01-01

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

  10. Nuclear RNA-seq of single neurons reveals molecular signatures of activation.

    PubMed

    Lacar, Benjamin; Linker, Sara B; Jaeger, Baptiste N; Krishnaswami, Suguna; Barron, Jerika; Kelder, Martijn; Parylak, Sarah; Paquola, Apuã; Venepally, Pratap; Novotny, Mark; O'Connor, Carolyn; Fitzpatrick, Conor; Erwin, Jennifer; Hsu, Jonathan Y; Husband, David; McConnell, Michael J; Lasken, Roger; Gage, Fred H

    2016-04-19

    Single-cell sequencing methods have emerged as powerful tools for identification of heterogeneous cell types within defined brain regions. Application of single-cell techniques to study the transcriptome of activated neurons can offer insight into molecular dynamics associated with differential neuronal responses to a given experience. Through evaluation of common whole-cell and single-nuclei RNA-sequencing (snRNA-seq) methods, here we show that snRNA-seq faithfully recapitulates transcriptional patterns associated with experience-driven induction of activity, including immediate early genes (IEGs) such as Fos, Arc and Egr1. SnRNA-seq of mouse dentate granule cells reveals large-scale changes in the activated neuronal transcriptome after brief novel environment exposure, including induction of MAPK pathway genes. In addition, we observe a continuum of activation states, revealing a pseudotemporal pattern of activation from gene expression alone. In summary, snRNA-seq of activated neurons enables the examination of gene expression beyond IEGs, allowing for novel insights into neuronal activation patterns in vivo.

  11. Nuclear RNA-seq of single neurons reveals molecular signatures of activation

    PubMed Central

    Lacar, Benjamin; Linker, Sara B.; Jaeger, Baptiste N.; Krishnaswami, Suguna; Barron, Jerika; Kelder, Martijn; Parylak, Sarah; Paquola, Apuã; Venepally, Pratap; Novotny, Mark; O'Connor, Carolyn; Fitzpatrick, Conor; Erwin, Jennifer; Hsu, Jonathan Y.; Husband, David; McConnell, Michael J.; Lasken, Roger; Gage, Fred H.

    2016-01-01

    Single-cell sequencing methods have emerged as powerful tools for identification of heterogeneous cell types within defined brain regions. Application of single-cell techniques to study the transcriptome of activated neurons can offer insight into molecular dynamics associated with differential neuronal responses to a given experience. Through evaluation of common whole-cell and single-nuclei RNA-sequencing (snRNA-seq) methods, here we show that snRNA-seq faithfully recapitulates transcriptional patterns associated with experience-driven induction of activity, including immediate early genes (IEGs) such as Fos, Arc and Egr1. SnRNA-seq of mouse dentate granule cells reveals large-scale changes in the activated neuronal transcriptome after brief novel environment exposure, including induction of MAPK pathway genes. In addition, we observe a continuum of activation states, revealing a pseudotemporal pattern of activation from gene expression alone. In summary, snRNA-seq of activated neurons enables the examination of gene expression beyond IEGs, allowing for novel insights into neuronal activation patterns in vivo. PMID:27090946

  12. Opioids inhibit visceral afferent activation of catecholamine neurons in the solitary tract nucleus.

    PubMed

    Cui, R J; Roberts, B L; Zhao, H; Andresen, M C; Appleyard, S M

    2012-10-11

    Brainstem A2/C2 catecholamine (CA) neurons within the solitary tract nucleus (NTS) influence many homeostatic functions, including food intake, stress, respiratory and cardiovascular reflexes. They also play a role in both opioid reward and withdrawal. Injections of opioids into the NTS modulate many autonomic functions influenced by catecholamine neurons including food intake and cardiac function. We recently showed that NTS-CA neurons are directly activated by incoming visceral afferent inputs. Here we determined whether opioid agonists modulate afferent activation of NTS-CA neurons using transgenic mice with EGFP expressed under the control of the tyrosine hydroxylase promoter (TH-EGFP) to identify catecholamine neurons. The opioid agonist Met-enkephalin (Met-Enk) significantly attenuated solitary tract-evoked excitatory postsynaptic currents (ST-EPSCs) in NTS TH-EGFP neurons by 80%, an effect reversed by wash or the mu opioid receptor-specific antagonist D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH(2) (CTOP). Met-Enk had a significantly greater effect to inhibit afferent inputs onto TH-EGFP-positive neurons than EGFP-negative neurons, which were only inhibited by 50%. The mu agonist, DAMGO, also inhibited the ST-EPSC in TH-EGFP neurons in a dose-dependent manner. In contrast, neither the delta agonist DPDPE, nor the kappa agonist, U69,593, consistently inhibited the ST-EPSC amplitude. Met-Enk and DAMGO increased the paired pulse ratio, decreased the frequency, but not amplitude, of mini-EPSCs and had no effect on holding current, input resistance or current-voltage relationships in TH-EGFP neurons, suggesting a presynaptic mechanism of action on afferent terminals. Met-Enk significantly reduced both the basal firing rate of NTS TH-EGFP neurons and the ability of afferent stimulation to evoke an action potential. These results suggest that opioids inhibit NTS-CA neurons by reducing an excitatory afferent drive onto these neurons through presynaptic inhibition of

  13. Recovery of network-driven glutamatergic activity in rat hippocampal neurons during chronic glutamate receptor blockade.

    PubMed

    Leininger, Eric; Belousov, Andrei B

    2009-01-28

    Previous studies indicated that a long-term decrease in the activity of ionotropic glutamate receptors induces cholinergic activity in rat and mouse hypothalamic neuronal cultures. Here we studied whether a prolonged inactivation of ionotropic glutamate receptors also induces cholinergic activity in hippocampal neurons. Receptor activity was chronically suppressed in rat hippocampal primary neuronal cultures with two proportionally increasing sets of concentrations of NMDA plus non-NMDA receptor antagonists: 100 microM/10 microM AP5/CNQX (1X cultures) and 200 microM/20 microM AP5/CNQX (2X cultures). Using calcium imaging we demonstrate that cholinergic activity does not develop in these cultures. Instead, network-driven glutamate-dependent activity, that normally is detected in hyper-excitable conditions, reappears in each culture group in the presence of these antagonists and can be reversibly suppressed by higher concentrations of AP5/CNQX. This activity is mediated by non-NMDA receptors and is modulated by NMDA receptors. Further, non-NMDA receptors, the general level of glutamate receptor activity and CaMK-dependent signaling are critical for development of this network-driven glutamatergic activity in the presence of receptor antagonists. Using electrophysiology, western blotting and calcium imaging we show that some neuronal parameters are either reduced or not affected by chronic glutamate receptor blockade. However, other parameters (including neuronal excitability, mEPSC frequency, and expression of GluR1, NR1 and betaCaMKII) become up-regulated and, in some cases, proportionally between the non-treated, 1X and 2X cultures. Our data suggest recovery of the network-driven glutamatergic activity after chronic glutamate receptor blockade. This recovery may represent a form of neuronal plasticity that compensates for the prolonged suppression of the activity of glutamate receptors.

  14. Activation of Six1 Expression in Vertebrate Sensory Neurons

    PubMed Central

    Sato, Shigeru; Yajima, Hiroshi; Furuta, Yasuhide; Ikeda, Keiko; Kawakami, Kiyoshi

    2015-01-01

    SIX1 homeodomain protein is one of the essential key regulators of sensory organ development. Six1-deficient mice lack the olfactory epithelium, vomeronasal organs, cochlea, vestibule and vestibuloacoustic ganglion, and also show poor neural differentiation in the distal part of the cranial ganglia. Simultaneous loss of both Six1 and Six4 leads to additional abnormalities such as small trigeminal ganglion and abnormal dorsal root ganglia (DRG). The aim of this study was to understand the molecular mechanism that controls Six1 expression in sensory organs, particularly in the trigeminal ganglion and DRG. To this end, we focused on the sensory ganglia-specific Six1 enhancer (Six1-8) conserved between chick and mouse. In vivo reporter assays using both animals identified an important core region comprising binding consensus sequences for several transcription factors including nuclear hormone receptors, TCF/LEF, SMAD, POU homeodomain and basic-helix-loop-helix proteins. The results provided information on upstream factors and signals potentially relevant to Six1 regulation in sensory neurons. We also report the establishment of a new transgenic mouse line (mSix1-8-NLSCre) that expresses Cre recombinase under the control of mouse Six1-8. Cre-mediated recombination was detected specifically in ISL1/2-positive sensory neurons of Six1-positive cranial sensory ganglia and DRG. The unique features of the mSix1-8-NLSCre line are the absence of Cre-mediated recombination in SOX10-positive glial cells and central nervous system and ability to induce recombination in a subset of neurons derived from the olfactory placode/epithelium. This mouse model can be potentially used to advance research on sensory development. PMID:26313368

  15. Simultaneous multi-patch-clamp and extracellular-array recordings: Single neuron reflects network activity

    NASA Astrophysics Data System (ADS)

    Vardi, Roni; Goldental, Amir; Sardi, Shira; Sheinin, Anton; Kanter, Ido

    2016-11-01

    The increasing number of recording electrodes enhances the capability of capturing the network’s cooperative activity, however, using too many monitors might alter the properties of the measured neural network and induce noise. Using a technique that merges simultaneous multi-patch-clamp and multi-electrode array recordings of neural networks in-vitro, we show that the membrane potential of a single neuron is a reliable and super-sensitive probe for monitoring such cooperative activities and their detailed rhythms. Specifically, the membrane potential and the spiking activity of a single neuron are either highly correlated or highly anti-correlated with the time-dependent macroscopic activity of the entire network. This surprising observation also sheds light on the cooperative origin of neuronal burst in cultured networks. Our findings present an alternative flexible approach to the technique based on a massive tiling of networks by large-scale arrays of electrodes to monitor their activity.

  16. Simultaneous multi-patch-clamp and extracellular-array recordings: Single neuron reflects network activity

    PubMed Central

    Vardi, Roni; Goldental, Amir; Sardi, Shira; Sheinin, Anton; Kanter, Ido

    2016-01-01

    The increasing number of recording electrodes enhances the capability of capturing the network’s cooperative activity, however, using too many monitors might alter the properties of the measured neural network and induce noise. Using a technique that merges simultaneous multi-patch-clamp and multi-electrode array recordings of neural networks in-vitro, we show that the membrane potential of a single neuron is a reliable and super-sensitive probe for monitoring such cooperative activities and their detailed rhythms. Specifically, the membrane potential and the spiking activity of a single neuron are either highly correlated or highly anti-correlated with the time-dependent macroscopic activity of the entire network. This surprising observation also sheds light on the cooperative origin of neuronal burst in cultured networks. Our findings present an alternative flexible approach to the technique based on a massive tiling of networks by large-scale arrays of electrodes to monitor their activity. PMID:27824075

  17. Activation of A-type gamma-aminobutyric acid receptors excites gonadotropin-releasing hormone neurons.

    PubMed

    DeFazio, R Anthony; Heger, Sabine; Ojeda, Sergio R; Moenter, Suzanne M

    2002-12-01

    Gamma-aminobutyric acid (GABA), acting through GABA(A) receptors (GABA(A)R), is hypothesized to suppress reproduction by inhibiting GnRH secretion, but GABA actions directly on GnRH neurons are not well established. In green fluorescent protein-identified adult mouse GnRH neurons in brain slices, gramicidin-perforated-patch-clamp experiments revealed the reversal potential (E(GABA)) for current through GABA(A)Rs was depolarized relative to the resting potential. Furthermore, rapid GABA application elicited action potentials in GnRH neurons but not controls. The consequence of GABA(A)R activation depends on intracellular chloride levels, which are maintained by homeostatic mechanisms. Membrane proteins that typically extrude chloride (KCC-2 cotransporter, CLC-2 channel) were absent from the GT1-7 immortalized GnRH cell line and GnRH neurons in situ or were not localized to the proper cell compartment for function. In contrast, GT1-7 cells and some GnRH neurons expressed the chloride-accumulating cotransporter, NKCC-1. Patch-clamp experiments showed that blockade of NKCC hyperpolarized E(GABA) by lowering intracellular chloride. Regardless of reproductive state, rapid GABA application excited GnRH neurons. In contrast, bath application of the GABA(A)R agonist muscimol transiently increased then suppressed firing; suppression persisted 4-15 min. Rapid activation of GABA(A)R thus excites GnRH neurons whereas prolonged activation reduces excitability, suggesting the physiological consequence of synaptic activation of GABA(A)R in GnRH neurons is excitation.

  18. Substance P excites GABAergic neurons in the mouse central amygdala through neurokinin 1 receptor activation

    PubMed Central

    Sosulina, L.; Strippel, C.; Romo-Parra, H.; Walter, A. L.; Kanyshkova, T.; Sartori, S. B.; Lange, M. D.; Singewald, N.

    2015-01-01

    Substance P (SP) is implicated in stress regulation and affective and anxiety-related behavior. Particularly high expression has been found in the main output region of the amygdala complex, the central amygdala (CE). Here we investigated the cellular mechanisms of SP in CE in vitro, taking advantage of glutamic acid decarboxylase-green fluorescent protein (GAD67-GFP) knockin mice that yield a reliable labeling of GABAergic neurons, which comprise 95% of the neuronal population in the lateral section of CE (CEl). In GFP-positive neurons within CEl, SP caused a membrane depolarization and increase in input resistance, associated with an increase in action potential firing frequency. Under voltage-clamp conditions, the SP-specific membrane current reversed at −101.5 ± 2.8 mV and displayed inwardly rectifying properties indicative of a membrane K+ conductance. Moreover, SP responses were blocked by the neurokinin type 1 receptor (NK1R) antagonist L-822429 and mimicked by the NK1R agonist [Sar9,Met(O2)11]-SP. Immunofluorescence staining confirmed localization of NK1R in GFP-positive neurons in CEl, predominantly in PKCδ-negative neurons (80%) and in few PKCδ-positive neurons (17%). Differences in SP responses were not observed between the major types of CEl neurons (late firing, regular spiking, low-threshold bursting). In addition, SP increased the frequency and amplitude of GABAergic synaptic events in CEl neurons depending on upstream spike activity. These data indicate a NK1R-mediated increase in excitability and GABAergic activity in CEl neurons, which seems to mostly involve the PKCδ-negative subpopulation. This influence can be assumed to increase reciprocal interactions between CElon and CEloff pathways, thereby boosting the medial CE (CEm) output pathway and contributing to the anxiogenic-like action of SP in the amygdala. PMID:26334021

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

    PubMed Central

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

    2017-01-01

    Dopamine (DA) and orexin neurons play important roles in reward and food intake. There are anatomical and functional connections between these two cell groups, where orexin peptides stimulate DA neurons in the ventral tegmental area and DA inhibits orexin neurons in the hypothalamus. However, the cellular mechanisms underlying DA action on orexin neurons remain incompletely understood. Therefore, the effect of DA on inhibitory transmission to orexin neurons was investigated in rat brain slices using whole cell patch clamp technique. We found that DA modulated the frequency of spontaneous and miniature IPSCs (mIPSCs) in a concentration dependent, bidirectional manner. Low (1 μM) and high concentrations (100 μM) of DA decreased and increased IPSC frequency, respectively. These effects did not accompany a change in mIPSC amplitude and persisted in the presence of G protein signaling inhibitor GDPβS in the pipette, suggesting that DA acts presynaptically. The decrease in mIPSC frequency was mediated by D2 receptors, whereas the increase required co-activation of D1 and D2 receptors and subsequent activation of phospholipase C. In summary, our results suggest that DA has complex effects on GABAergic transmission to orexin neurons, involving cooperation of multiple receptor subtypes. The direction of dopaminergic influence on orexin neurons is dependent on the level of DA in the hypothalamus. At low levels DA disinhibits orexin neurons whereas at high levels it facilitates GABA release, which may act as negative feedback to curb the excitatory orexinergic output to DA neurons. These mechanisms may have implications for consummatory and motivated behaviours. PMID:26036709

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

    PubMed

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

    2015-08-01

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

  1. Sensory deprivation regulates the development of the hyperpolarization-activated current in auditory brainstem neurons.

    PubMed

    Hassfurth, Benjamin; Magnusson, Anna K; Grothe, Benedikt; Koch, Ursula

    2009-10-01

    Hyperpolarization-activated and cyclic nucleotide-gated (HCN) channels are highly expressed in the superior olivary complex, the primary locus for binaural information processing. This hyperpolarization-activated current (I(h)) regulates the excitability of neurons and enhances the temporally precise analysis of the binaural acoustic cues. By using the whole-cell patch-clamp technique, we examined the properties of I(h) current in neurons of the lateral superior olive (LSO) and the medial nucleus of the trapezoid body (MNTB) before and after hearing onset. Moreover, we tested the hypothesis that I(h) currents are actively regulated by sensory input activity by performing bilateral and unilateral cochlear ablations before hearing onset, resulting in a chronic auditory deprivation. The results show that after hearing onset, I(h) currents are rapidly upregulated in LSO neurons, but change only marginally in neurons of the MNTB. We also found a striking difference in maximal current density, voltage dependence and activation time constant between the LSO and the MNTB in mature-like animals. Following bilateral cochlear ablations before hearing onset, the I(h) currents were scaled up in the LSO and scaled down in the MNTB. Consequently, in the LSO this resulted in a depolarized resting membrane potential and a lower input resistance of these neurons. This type of activity-dependent homeostatic change could thus result in an augmented response to the remaining inputs.

  2. Calcium-activated chloride current expression in axotomized sensory neurons: what for?

    PubMed Central

    Boudes, Mathieu; Scamps, Frédérique

    2012-01-01

    Calcium-activated chloride currents (CaCCs) are activated by an increase in intracellular calcium concentration. Peripheral nerve injury induces the expression of CaCCs in a subset of adult sensory neurons in primary culture including mechano- and proprioceptors, though not nociceptors. Functional screenings of potential candidate genes established that Best1 is a molecular determinant for CaCC expression among axotomized sensory neurons, while Tmem16a is acutely activated by inflammatory mediators in nociceptors. In nociceptors, such CaCCs are preferentially activated under receptor-induced calcium mobilization contributing to cell excitability and pain. In axotomized mechano- and proprioceptors, CaCC activation does not promote electrical activity and prevents firing, a finding consistent with electrical silencing for growth competence of adult sensory neurons. In favor of a role in the process of neurite growth, CaCC expression is temporally correlated to neurons displaying a regenerative mode of growth. This perspective focuses on the molecular identity and role of CaCC in axotomized sensory neurons and the future directions to decipher the cellular mechanisms regulating CaCC during neurite (re)growth. PMID:22461766

  3. Lactate modulates the activity of primary cortical neurons through a receptor-mediated pathway.

    PubMed

    Bozzo, Luigi; Puyal, Julien; Chatton, Jean-Yves

    2013-01-01

    Lactate is increasingly described as an energy substrate of the brain. Beside this still debated metabolic role, lactate may have other effects on brain cells. Here, we describe lactate as a neuromodulator, able to influence the activity of cortical neurons. Neuronal excitability of mouse primary neurons was monitored by calcium imaging. When applied in conjunction with glucose, lactate induced a decrease in the spontaneous calcium spiking frequency of neurons. The effect was reversible and concentration dependent (IC50 ∼4.2 mM). To test whether lactate effects are dependent on energy metabolism, we applied the closely related substrate pyruvate (5 mM) or switched to different glucose concentrations (0.5 or 10 mM). None of these conditions reproduced the effect of lactate. Recently, a Gi protein-coupled receptor for lactate called HCA1 has been introduced. To test if this receptor is implicated in the observed lactate sensitivity, we incubated cells with pertussis toxin (PTX) an inhibitor of Gi-protein. PTX prevented the decrease of neuronal activity by L-lactate. Moreover 3,5-dyhydroxybenzoic acid, a specific agonist of the HCA1 receptor, mimicked the action of lactate. This study indicates that lactate operates a negative feedback on neuronal activity by a receptor-mediated mechanism, independent from its intracellular metabolism.

  4. Lactate Modulates the Activity of Primary Cortical Neurons through a Receptor-Mediated Pathway

    PubMed Central

    Bozzo, Luigi; Puyal, Julien; Chatton, Jean-Yves

    2013-01-01

    Lactate is increasingly described as an energy substrate of the brain. Beside this still debated metabolic role, lactate may have other effects on brain cells. Here, we describe lactate as a neuromodulator, able to influence the activity of cortical neurons. Neuronal excitability of mouse primary neurons was monitored by calcium imaging. When applied in conjunction with glucose, lactate induced a decrease in the spontaneous calcium spiking frequency of neurons. The effect was reversible and concentration dependent (IC50 ∼4.2 mM). To test whether lactate effects are dependent on energy metabolism, we applied the closely related substrate pyruvate (5 mM) or switched to different glucose concentrations (0.5 or 10 mM). None of these conditions reproduced the effect of lactate. Recently, a Gi protein-coupled receptor for lactate called HCA1 has been introduced. To test if this receptor is implicated in the observed lactate sensitivity, we incubated cells with pertussis toxin (PTX) an inhibitor of Gi-protein. PTX prevented the decrease of neuronal activity by L-lactate. Moreover 3,5-dyhydroxybenzoic acid, a specific agonist of the HCA1 receptor, mimicked the action of lactate. This study indicates that lactate operates a negative feedback on neuronal activity by a receptor-mediated mechanism, independent from its intracellular metabolism. PMID:23951229

  5. Potassium channels control the interaction between active dendritic integration compartments in layer 5 cortical pyramidal neurons

    PubMed Central

    Harnett, Mark T.; Xu, Ning-Long; Magee, Jeffrey C.; Williams, Stephen R.

    2013-01-01

    Active dendritic synaptic integration enhances the computational power of neurons. Such nonlinear processing generates an object-localization signal in the apical dendritic tuft of layer 5B cortical pyramidal neurons during sensory-motor behaviour. Here we employ electrophysiological and optical approaches in brain-slices and behaving animals to investigate how excitatory synaptic input to this distal dendritic compartment influences neuronal output. We find that active dendritic integration throughout the apical dendritic tuft is highly compartmentalized by voltage-gated potassium (KV) channels. A high-density of both transient and sustained KV channels was observed in all apical dendritic compartments. These channels potently regulated the interaction between apical dendritic tuft, trunk, and axo-somatic integration zones to control neuronal output in vitro as well as the engagement of dendritic nonlinear processing in vivo during sensory-motor behaviour. Thus, KV channels dynamically tune the interaction between active dendritic integration compartments in layer 5B pyramidal neurons to shape behaviourally relevant neuronal computations. PMID:23931999

  6. Procedure for recording the simultaneous activity of single neurons distributed across cortical areas during sensory discrimination

    PubMed Central

    Hernández, Adrián; Nácher, Verónica; Luna, Rogelio; Alvarez, Manuel; Zainos, Antonio; Cordero, Silvia; Camarillo, Liliana; Vázquez, Yuriria; Lemus, Luis; Romo, Ranulfo

    2008-01-01

    We report a procedure for recording the simultaneous activity of single neurons distributed across five cortical areas in behaving monkeys. The procedure consists of a commercially available microdrive adapted to a commercially available neural data collection system. The critical advantage of this procedure is that, in each cortical area, a configuration of seven microelectrodes spaced 250–500 μm can be inserted transdurally and each can be moved independently in the z axis. For each microelectrode, the data collection system can record the activity of up to five neurons together with the local field potential (LFP). With this procedure, we normally monitor the simultaneous activity of 70–100 neurons while trained monkeys discriminate the difference in frequency between two vibrotactile stimuli. Approximately 20–60 of these neurons have response properties previously reported in this task. The neuronal recordings show good signal-to-noise ratio, are remarkably stable along a 1-day session, and allow testing several protocols. Microelectrodes are removed from the brain after a 1-day recording session, but are reinserted again the next day by using the same or different x-y microelectrode array configurations. The fact that microelectrodes can be moved in the z axis during the recording session and that the x-y configuration can be changed from day to day maximizes the probability of studying simultaneous interactions, both local and across distant cortical areas, between neurons associated with the different components of this task. PMID:18946031

  7. FoxP2 expression defines dorsolateral pontine neurons activated by sodium deprivation*

    PubMed Central

    Geerling, Joel C; Stein, Matthew K; Miller, Rebecca L; Shin, Jung-Won; Gray, Paul A; Loewy, Arthur D

    2010-01-01

    Two specific groups of neurons in the dorsolateral pons are activated by dietary sodium deprivation. These two groups are the pre-locus coeruleus (pre-LC) and the inner subdivision of the external lateral parabrachial nucleus (PBel-inner). In each site, after rats are fed an extremely low-sodium diet for over a week, neurons increase their expression of an activity-induced transcription factor, c-Fos. Here, we confirm this observation and extend it by demonstrating that these two groups of neurons express a common marker gene, the constitutively-expressed transcription factor Forkhead box protein 2 (FoxP2). That is, virtually all of the c-Fos activated neurons in both regions also express FoxP2. The expression of FoxP2 by both these groups of neurons suggests that they are developmentally-related subsets derived from the same basic population. Given that FoxP2, unlike c-Fos, is expressed independent of sodium deprivation, this marker may be useful in future studies of the pre-LC and PBel-inner. The molecular definition of these neurons, which project to circuits in the forebrain that influence visceral, appetitive, and hedonic functions, may allow direct experimental exploration of the functional role of these circuits using genetic tools. PMID:21108936

  8. Dynamic synchronization of ongoing neuronal activity across spinal segments regulates sensory information flow.

    PubMed

    Contreras-Hernández, E; Chávez, D; Rudomin, P

    2015-05-15

    Previous studies on the correlation between spontaneous cord dorsum potentials recorded in the lumbar spinal segments of anaesthetized cats suggested the operation of a population of dorsal horn neurones that modulates, in a differential manner, transmission along pathways mediating Ib non-reciprocal postsynaptic inhibition and pathways mediating primary afferent depolarization and presynaptic inhibition. In order to gain further insight into the possible neuronal mechanisms that underlie this process, we have measured changes in the correlation between the spontaneous activity of individual dorsal horn neurones and the cord dorsum potentials associated with intermittent activation of these inhibitory pathways. We found that high levels of neuronal synchronization within the dorsal horn are associated with states of incremented activity along the pathways mediating presynaptic inhibition relative to pathways mediating Ib postsynaptic inhibition. It is suggested that ongoing changes in the patterns of functional connectivity within a distributed ensemble of dorsal horn neurones play a relevant role in the state-dependent modulation of impulse transmission along inhibitory pathways, among them those involved in the central control of sensory information. This feature would allow the same neuronal network to be involved in different functional tasks.

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

    PubMed

    Croft, Wayne; Dobson, Katharine L; Bellamy, Tomas C

    2015-01-01

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

  10. Cyclooxygenase-1 and -2 in spinally projecting neurons are involved in CRF-induced sympathetic activation.

    PubMed

    Yamaguchi, Naoko; Okada, Shoshiro

    2009-12-03

    Corticotropin-releasing factor (CRF) in the brain has been shown to stimulate sympathetic activity, leading to elevations of blood pressure, heart rate and plasma catecholamine levels and neuronal activation of the sympathetic ganglia and adrenal medulla. We previously reported that brain cyclooxygenase (COX), the rate-limiting enzyme in the synthesis of prostanoids, is involved in centrally administered CRF-induced sympathetic activation in rats. Therefore, the present study was designed to reveal the effect of centrally administered CRF (1.5 nmol/animal) on the expression of COX isozymes, COX-1 and COX-2, in spinally projecting neurons until 6h after the administration, using rats microinjected with a monosynaptic retrograde tracer into the intermediolateral cell column of the thoracic spinal cord. Retrogradely labeled neurons were detected in the paraventricular hypothalamic nucleus (PVN), locus coeruleus (LC), raphe pallidus nucleus and rostral ventrolateral medulla. Centrally administered CRF significantly increased the number of spinally projecting PVN neurons expressing COX-1 throughout the experimental period and those expressing COX-2 during only the late phase. CRF also increased the number of spinally projecting LC neurons expressing COX-2 throughout the experimental period. In other regions, the CRF administration had no effect on COXs expression in spinally projecting neurons. These results suggest that COX-1 and COX-2 in the PVN and COX-2 in the LC play roles in the CRF-induced sympathetic regulation in rats.

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

    PubMed Central

    Croft, Wayne; Dobson, Katharine L.; Bellamy, Tomas C.

    2015-01-01

    The capacity of synaptic networks to express activity-dependent changes in strength and connectivity is essential for learning and memory processes. In recent years, glial cells (most notably astrocytes) have been recognized as active participants in the modulation of synaptic transmission and synaptic plasticity, implicating these electrically nonexcitable cells in information processing in the brain. While the concept of bidirectional communication between neurons and glia and the mechanisms by which gliotransmission can modulate neuronal function are well established, less attention has been focussed on the computational potential of neuron-glial transmission itself. In particular, whether neuron-glial transmission is itself subject to activity-dependent plasticity and what the computational properties of such plasticity might be has not been explored in detail. In this review, we summarize current examples of plasticity in neuron-glial transmission, in many brain regions and neurotransmitter pathways. We argue that induction of glial plasticity typically requires repetitive neuronal firing over long time periods (minutes-hours) rather than the short-lived, stereotyped trigger typical of canonical long-term potentiation. We speculate that this equips glia with a mechanism for monitoring average firing rates in the synaptic network, which is suited to the longer term roles proposed for astrocytes in neurophysiology. PMID:26339509

  12. sigma Receptor activation blocks potassium channels and depresses neuroexcitability in rat intracardiac neurons.

    PubMed

    Zhang, Hongling; Cuevas, Javier

    2005-06-01

    The sigma receptors have been implicated in the regulation of the cardiovascular system, and sigma-1 receptor transcripts have been found in parasympathetic intracardiac neurons. However, the cellular function of sigma-1 receptors in these cells remains to be determined. Effects of sigma receptor activation on voltage-activated K(+) channels and action potential firing were studied in isolated intracardiac neurons using whole-cell patch-clamp recording techniques. Activation of sigma receptors reversibly blocked delayed outwardly rectifying potassium channels, large conductance Ca(2+)-sensitive K(+) channels, and the M-current with maximal inhibition >80%. The inhibition of K(+) channels by sigma ligands was dose-dependent, and the rank order potency of (+)-pentazocine > ibogaine > 1,3-di-O-tolyguanidin (DTG) suggests that the effect is mediated by sigma-1 receptor activation. Preincubation of neurons with the irreversible sigma receptor antagonist metaphit blocked DTG-induced inhibition of K(+) channels, confirming that the effect is mediated by sigma receptor activation. Although bath application of sigma ligands depolarized intracardiac neurons, the number of action potentials fired by the cells in response to depolarizing current pulses was decreased in the presence of these drugs. Neither dialysis of the neurons nor application of intracellular 5'-O-(2-thiodiphosphate) trilithium salt inhibited the effect of sigma receptors on K(+) channels, which suggests that the signal transduction pathway does not involve a diffusible cytosolic second messenger or a G protein. Together, these data suggest that sigma-1 receptors are directly coupled to K(+) channels in intracardiac neurons. Furthermore, activation of sigma-1 receptors depresses the excitability of intracardiac neurons and is thus likely to block parasympathetic input to the heart.

  13. Improved visualization of neuronal injury following glial activation by manganese enhanced MRI.

    PubMed

    Bade, Aditya N; Zhou, Biyun; Epstein, Adrian A; Gorantla, Santhi; Poluektova, Larisa Y; Luo, Jiangtao; Gendelman, Howard E; Boska, Michael D; Liu, Yutong

    2013-09-01

    Research directed at anatomical, integrative and functional activities of the central nervous system (CNS) can be realized through bioimaging. A wealth of data now demonstrates the utility of magnetic resonance imaging (MRI) towards unraveling complex neural connectivity operative in health and disease. A means to improve MRI sensitivity is through contrast agents and notably manganese (Mn²⁺). The Mn²⁺ ions enter neurons through voltage-gated calcium channels and unlike other contrast agents such as gadolinium, iron oxide, iron platinum and imaging proteins, provide unique insights into brain physiology. Nonetheless, a critical question that remains is the brain target cells serving as sources for the signal of Mn²⁺ enhanced MRI (MEMRI). To this end, we investigated MEMRI's abilities to detect glial (astrocyte and microglia) and neuronal activation signals following treatment with known inflammatory inducing agents. The idea is to distinguish between gliosis (glial activation) and neuronal injury for the MEMRI signal and as such use the agent as a marker for neural activity in inflammatory and degenerative disease. We now demonstrate that glial inflammation facilitates Mn²⁺ neuronal ion uptake. Glial Mn²⁺ content was not linked to its activation. MEMRI performed on mice injected intracranially with lipopolysaccharide was associated with increased neuronal activity. These results support the notion that MEMRI reflects neuronal excitotoxicity and impairment that can occur through a range of insults including neuroinflammation. We conclude that the MEMRI signal enhancement is induced by inflammation stimulating neuronal Mn²⁺ uptake.

  14. Persistent cue-evoked activity of accumbens neurons after prolonged abstinence from self-administered cocaine.

    PubMed

    Ghitza, Udi E; Fabbricatore, Anthony T; Prokopenko, Volodymyr; Pawlak, Anthony P; West, Mark O

    2003-08-13

    Persistent neural processing of information regarding drug-predictive environmental stimuli may be involved in motivating drug abusers to engage in drug seeking after abstinence. The addictive effects of various drugs depend on the mesocorticolimbic dopamine system innervating the nucleus accumbens. We used single-unit recording in rats to test whether accumbens neurons exhibit responses to a discriminative stimulus (SD) tone previously paired with cocaine availability during cocaine self-administration. Presentation of the tone after 3-4 weeks of abstinence resulted in a cue-induced relapse of drug seeking under extinction conditions. Accumbens neurons did not exhibit tone-evoked activity before cocaine self-administration training but exhibited significant SD tone-evoked activity during extinction. Under extinction conditions, shell neurons exhibited significantly greater activity evoked by the SD tone than that evoked by a neutral tone (i.e., never paired with reinforcement). In contrast, core neurons responded indiscriminately to presentations of the SD tone or the neutral tone. Accumbens shell neurons exhibited significantly greater SD tone-evoked activity than did accumbens core neurons. Although the onset of SD tone-evoked activity occurred well before the earliest movements commenced (150 msec), this activity often persisted beyond the onset of tone-evoked movements. These results indicate that accumbens shell neurons exhibit persistent processing of information regarding reward-related stimuli after prolonged drug abstinence. Moreover, the accumbens shell appears to be involved in discriminating the motivational value of reward-related associative stimuli, whereas the accumbens core does not.

  15. Optical imaging of neural activity: from neuron to brain

    NASA Astrophysics Data System (ADS)

    Luo, Qingming; Zeng, Shaoqun; Gong, Hui

    2003-12-01

    This paper introduces the optical imaging approaches at three levels in cognitive neuroscience in the Key Laboratory of Biomedical Photonics of Ministry of Education of China. In molecular and cellular level, the advances in microscopy, molecular optical marker, and sample preparations have made possible studies that characterize the form and function of neurons in unprecedented detail. The development of two-photon excitation has enabled fluorescent imaging of small structures in the midst of highly scattering media with little photodamage. The combination of MPE and multi-electrode array provides a powerful approach for neuronal networks imaging. Intrinsic signal imaging (ISI) and laser speckle imaging (LSI) are effective approaches for intrinsic signal imaging at a given cortical site. No alternative imaging technique for the visualization of functional organization in the living brain provides a comparable spatial resolution. It is this level of resolution that reveals where processing is performed - a necessary step for the understanding of the neural code at the population level. Completely noninvasive optical imaging through the intact human skull, such as functional near infrared imaging may provide an imaging tool offering both the spatial and the temporal resolutions required to expand our knowledge of the principles underlying the remarkable performance of the human cerebral cortex.

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

    PubMed

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

    2014-11-14

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

  17. Fear conditioning suppresses large-conductance calcium-activated potassium channels in lateral amygdala neurons.

    PubMed

    Sun, P; Zhang, Q; Zhang, Y; Wang, F; Wang, L; Yamamoto, R; Sugai, T; Kato, N

    2015-01-01

    It was previously shown that depression-like behavior is accompanied with suppression of the large-conductance calcium activated potassium (BK) channel in cingulate cortex pyramidal cells. To test whether BK channels are also involved in fear conditioning, we studied neuronal properties of amygdala principal cells in fear conditioned mice. After behavior, we made brain slices containing the amygdala, the structure critically relevant to fear memory. The resting membrane potential in lateral amygdala (LA) neurons obtained from fear conditioned mice (FC group) was more depolarized than in neurons from naïve controls. The frequencies of spikes evoked by current injections were higher in neurons from FC mice, demonstrating that excitability of LA neurons was elevated by fear conditioning. The depolarization in neurons from FC mice was shown to depend on BK channels by using the BK channel blocker charybdotoxin. Suppression of BK channels in LA neurons from the FC group was further confirmed on the basis of the spike width, since BK channels affect the descending phase of spikes. Spikes were broader in the FC group than those in the naïve control in a manner dependent on BK channels. Consistently, quantitative real-time PCR revealed a decreased expression of BK channel mRNA. The present findings suggest that emotional disorder manifested in the forms of fear conditioning is accompanied with BK channel suppression in the amygdala, the brain structure critical to this emotional disorder.

  18. Laser speckle contrast reveals cerebral blood flow dynamics evoked by optogenetically controlled neuronal activity

    NASA Astrophysics Data System (ADS)

    Li, Nan; Thakor, Nitish V.; Pelled, Galit

    2013-03-01

    As a critical basis of functional brain imaging, neurovascular coupling describes the link between neuronal and hemodynamic changes. The majority of in vivo neurovascular coupling studies was performed by inducing sensory stimulation via afferent inputs. Unfortunately such an approach results in recruiting of multiple types of cells, which confounds the explanation of neuronal roles in stimulus evoked hemodynamic changes. Recently optogenetics has emerged to provide immediate control of neurons by exciting or inhibiting genetically engineered neurons expressing light sensitive proteins. However, there is a need for optical methods capable of imaging the concurrent hemodynamic changes. We utilize laser speckle contrast imaging (LSCI) to obtain high resolution display of cerebral blood flow (CBF) in the vicinity of the targeted neural population. LSCI is a minimally invasive method for imaging CBF in microvessels through thinned skull, and produces images with high spatiotemporal resolution, wide field of view. In the integrated system light sources with different wavelengths and band-passing/blocking filters were used to allow simultaneous optical manipulation of neuronal activities and optical imaging of corresponding CBF. Experimental studies were carried out in a rodent model expressing channalrhodopsin (ChR2) in excitatory neurons in the somatosensory cortex (S1). The results demonstrated significant increases of CBF in response to ChR2 stimulation (exciting neuronal firing) comparable to the CBF response to contralateral forepaw stimulation. The approach promises to be an exciting minimally invasive method to study neurovascular coupling. The complete system provides a novel approach for broad neuroscience applications.

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

    PubMed

    Zhou, Li; Liu, Ming-Zhe; Li, Qing; Deng, Juan; Mu, Di; Sun, Yan-Gang

    2017-03-21

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

  20. Mice lacking p35, a neuronal specific activator of Cdk5, display cortical lamination defects, seizures, and adult lethality.

    PubMed

    Chae, T; Kwon, Y T; Bronson, R; Dikkes, P; Li, E; Tsai, L H

    1997-01-01

    The adult mammalian cortex is characterized by a distinct laminar structure generated through a well-defined pattern of neuronal migration. Successively generated neurons are layered in an "inside-out" manner to produce six cortical laminae. We demonstrate here that p35, the neuronal-specific activator of cyclin-dependent kinase 5, plays a key role in proper neuronal migration. Mice lacking p35, and thus p35/cdk5 kinase activity, display severe cortical lamination defects and suffer from sporadic adult lethality and seizures. Histological examination reveals that the mutant mice lack the characteristic laminated structure of the cortex. Neuronal birth-dating experiments indicate a reversed packing order of cortical neurons such that earlier born neurons reside in superficial layers and later generated neurons occupy deep layers. The phenotype of p35 mutant mice thus demonstrates that the formation of cortical laminar structure depends on the action of the p35/cdk5 kinase.

  1. Neuromedin B and gastrin releasing peptide excite arcuate nucleus neuropeptide Y neurons in a novel transgenic mouse expressing strong renilla GFP in NPY neurons

    PubMed Central

    van den Pol, Anthony N.; Yao, Yang; Fu, Li-Ying; Foo, Kylie; Huang, Hao; Coppari, Roberto; Lowell, Brad; Broberger, Christian

    2009-01-01

    Neuropeptide Y (NPY) is one of the most widespread neuropeptides in the brain. Transgenic mice were generated that expressed bright renilla GFP in most or all of the known NPY cells in the brain, which otherwise were not identifiable. GFP expression in NPY cells was confirmed with immunocytochemistry and single cell RT-PCR. NPY neurons in the hypothalamic arcuate nucleus play an important role in energy homeostasis and endocrine control. Whole cell patch clamp recording was used to study identified arcuate NPY cells. Primary agents that regulate energy balance include melanocortin receptor agonists, AgRP, and cannabinoids; none of these substances substantially influenced electrical properties of NPY neurons. In striking contrast, neuropeptides of the bombesin family, including gastrin releasing peptide and neuromedin B which are found in axons in the arcuate nucleus and may also be released from the gut to signal the brain, showed strong direct excitatory actions at nanomolar levels on the NPY neurons, stronger than the actions of ghrelin and hypocretin/orexin. Bombesin-related peptides reduced input resistance and depolarized the membrane potential. The depolarization was attenuated by several factors: substitution of choline for sodium, extracellular Ni2+, inclusion of BAPTA in the pipette, KB-R7943 and SKF96365. Reduced extracellular calcium enhanced the current, which reversed around − 20 mV. Together, these data suggest two mechanisms, activation of non-selective cation channels and the sodium/calcium exchanger. Since both NPY and POMC neurons, which we also studied, are similarly directly excited by bombesin-like peptides, the peptides may function to initiate broad activation, rather than the cell-type selective activation or inhibition reported for many other compounds that modulate energy homeostasis. PMID:19357287

  2. Diverse impact of acute and long-term extracellular proteolytic activity on plasticity of neuronal excitability

    PubMed Central

    Wójtowicz, Tomasz; Brzdąk, Patrycja; Mozrzymas, Jerzy W.

    2015-01-01

    Learning and memory require alteration in number and strength of existing synaptic connections. Extracellular proteolysis within the synapses has been shown to play a pivotal role in synaptic plasticity by determining synapse structure, function, and number. Although synaptic plasticity of excitatory synapses is generally acknowledged to play a crucial role in formation of memory traces, some components of neural plasticity are reflected by nonsynaptic changes. Since information in neural networks is ultimately conveyed with action potentials, scaling of neuronal excitability could significantly enhance or dampen the outcome of dendritic integration, boost neuronal information storage capacity and ultimately learning. However, the underlying mechanism is poorly understood. With this regard, several lines of evidence and our most recent study support a view that activity of extracellular proteases might affect information processing in neuronal networks by affecting targets beyond synapses. Here, we review the most recent studies addressing the impact of extracellular proteolysis on plasticity of neuronal excitability and discuss how enzymatic activity may alter input-output/transfer function of neurons, supporting cognitive processes. Interestingly, extracellular proteolysis may alter intrinsic neuronal excitability and excitation/inhibition balance both rapidly (time of minutes to hours) and in long-term window. Moreover, it appears that by cleavage of extracellular matrix (ECM) constituents, proteases may modulate function of ion channels or alter inhibitory drive and hence facilitate active participation of dendrites and axon initial segments (AISs) in adjusting neuronal input/output function. Altogether, a picture emerges whereby both rapid and long-term extracellular proteolysis may influence some aspects of information processing in neurons, such as initiation of action potential, spike frequency adaptation, properties of action potential and dendritic

  3. Serotonin activates catecholamine neurons in the solitary tract nucleus by increasing spontaneous glutamate inputs.

    PubMed

    Cui, Ran Ji; Roberts, Brandon L; Zhao, Huan; Zhu, Mingyan; Appleyard, Suzanne M

    2012-11-14

    Serotonin (5-HT) is a critical neurotransmitter in the control of autonomic functions. 5-HT(3) receptors participate in vagal afferent feedback to decrease food intake and regulate cardiovascular reflexes; however, the phenotype of the solitary tract nucleus (NTS) neurons involved is not known. A(2)/C(2) catecholamine (CA) neurons in the NTS are directly activated by visceral afferents and are important for the control of food intake and cardiovascular function, making them good candidates to respond to and mediate the effects of serotonin at the level of the NTS. This study examines serotonin's effects on NTS-CA neurons using patch-clamp techniques and transgenic mice expressing an enhanced green fluorescent protein driven by the tyrosine hydroxylase (TH) promoter (TH-EGFP) to identify catecholamine neurons. Serotonin increased the frequency of spontaneous glutamate excitatory postsynaptic currents (sEPSCs) in >90% of NTS-TH-EGFP neurons, an effect blocked by the 5-HT(3) receptor antagonist ondansetron and mimicked by the 5-HT(3) receptor agonists SR5227 and mCPBG. In contrast, 5-HT(3) receptor agonists increased sEPSCs on a minority (<30%) of non-TH neurons. 5-HT(3) receptor agonists increased the frequency, but not the amplitude, of mini-EPSCs, suggesting that their actions are presynaptic. 5-HT(3) receptor agonists increased the firing rate of TH-EGFP neurons, an effect dependent on the increased spontaneous glutamate inputs as it was blocked by the ionotropic glutamate antagonist NBQX, but independent of visceral afferent activation. These results demonstrate a cellular mechanism by which serotonin activates NTS-TH neurons and suggest a pathway by which it can increase catecholamine release in target regions to modulate food intake, motivation, stress, and cardiovascular function.

  4. Serotonin Activates Catecholamine Neurons in the Solitary Tract Nucleus by Increasing Spontaneous Glutamate Inputs

    PubMed Central

    Cui, Ran Ji; Roberts, Brandon L.; Zhao, Huan; Zhu, Mingyan

    2012-01-01

    Serotonin (5-HT) is a critical neurotransmitter in the control of autonomic functions. 5-HT3 receptors participate in vagal afferent feedback to decrease food intake and regulate cardiovascular reflexes; however, the phenotype of the solitary tract nucleus (NTS) neurons involved is not known. A2/C2 catecholamine (CA) neurons in the NTS are directly activated by visceral afferents and are important for the control of food intake and cardiovascular function, making them good candidates to respond to and mediate the effects of serotonin at the level of the NTS. This study examines serotonin's effects on NTS-CA neurons using patch-clamp techniques and transgenic mice expressing an enhanced green fluorescent protein driven by the tyrosine hydroxylase (TH) promoter (TH-EGFP) to identify catecholamine neurons. Serotonin increased the frequency of spontaneous glutamate excitatory postsynaptic currents (sEPSCs) in >90% of NTS-TH-EGFP neurons, an effect blocked by the 5-HT3 receptor antagonist ondansetron and mimicked by the 5-HT3 receptor agonists SR5227 and mCPBG. In contrast, 5-HT3 receptor agonists increased sEPSCs on a minority (<30%) of non-TH neurons. 5-HT3 receptor agonists increased the frequency, but not the amplitude, of mini-EPSCs, suggesting that their actions are presynaptic. 5-HT3 receptor agonists increased the firing rate of TH-EGFP neurons, an effect dependent on the increased spontaneous glutamate inputs as it was blocked by the ionotropic glutamate antagonist NBQX, but independent of visceral afferent activation. These results demonstrate a cellular mechanism by which serotonin activates NTS-TH neurons and suggest a pathway by which it can increase catecholamine release in target regions to modulate food intake, motivation, stress, and cardiovascular function. PMID:23152635

  5. CNTF protects neurons from hypoxic injury through the activation of STAT3pTyr705.

    PubMed

    Gu, Ying Li; Gao, Guan Qun; Ma, Ning; Ye, Lin Lin; Zhang, Li Wei; Gao, Xu; Zhang, Zhuo Bo

    2016-12-01

    The aim of the present study was to investigate whether ciliary neurotrophic factor (CNTF) plays its neuroprotective role following hypoxic injury through the activation of signal transducer and activator of transcription 3 (STAT3) signaling. Firstly, to determine whether CNTF exerts its effects via STAT3 following hypoxic injury, cultured neurons from the cerebral cortex of mice were prepared and a neuronal model of hypoxia was then established. The neurons exposed to hypoxia were then pre-treated with CNTF and transfected with small interference RNA (siRNA) targeting STAT3 (STAT3 siRNA) using polybrene, or with STAT3Tyr705 mutant or STAT3Ser727 mutant using an electroporation system. The survival, proliferation and neurite outgrowth of the neurons subjected to different treatments were also determined. RT-qPCR and western blot analysis were employed to examine the expression levels of STAT3, p-STAT3Tyr705 and p-STAT3Ser727 following treatment with CNTF and other treatments. Our results revealed that treatment with CNTF: i) protected neurons from hypoxic injury by promoting survival and neurite growth; ii) induced a significant increase in the levels of STAT3, STAT3pTyr705 and the STAT3pTyr705/STAT3 ratio; it did not however, significantly affect the levels of STAT3pSer727 in the hypoxic cerebral cortex neurons. Transfection of the hypoxic neurons pre-treated with CNTF with STAT3 siRNA or STAT3Tyr705 neutralized the protective effects exerted by CNTF. The findings of our study thus demonstrate that CNTF protects neurons from hypoxic injury through the activation of STAT3pTyr705.

  6. Ethanol exposure in early adolescence inhibits intrinsic neuronal plasticity via sigma-1 receptor activation in hippocampal CA1 neurons

    PubMed Central

    Sabeti, Jilla

    2011-01-01

    Background We demonstrated previously that rats exposed to chronic intermittent ethanol (CIE) vapors in early adolescence show increased magnitudes of long-term potentiation (LTP) of excitatory transmission when recorded at dendritic synapses in hippocampus. Large amplitude LTP following CIE exposure is mediated by sigma-1 receptors; however, not yet addressed is the role of sigma-1 receptors in modulating the intrinsic properties of neurons to alter their action potential firing during LTP. Methods Activity-induced plasticity of spike firing was investigated using rat hippocampal slice recordings to measure changes in both field excitatory postsynaptic potentials (fEPSPs) and population spikes (pop. spikes) concomitantly at dendritic inputs and soma of CA1 pyramidal neurons, respectively. Results We observed unique modifications in plasticity of action potential firing in hippocampal slices from CIE exposed adolescent rats, where the induction of large amplitude LTP by 100 Hz stimulations was accompanied by reduced CA1 neuronal excitability—reflected as decreased pop. spike efficacy and impaired activity-induced fEPSP-to-spike (E-S) potentiation. By contrast, LTP induction in ethanol-naïve control slices resulted in increased spike efficacy and robust E-S potentiation. E-S potentiation impairments emerged at 24 hr after CIE treatment cessation, but not before the alcohol withdrawal period, and were restored with bath-application of the sigma-1 receptor selective antagonist BD1047, but not the NMDA receptor antagonist D-AP5. Further evidence revealed a significantly shortened somatic fEPSP time course in adolescent CIE-withdrawn hippocampal slices during LTP; however, paired-pulse data show no apparent correspondence between E-S dissociation and altered recurrent feedback inhibition. Conclusions Results here suggest that acute withdrawal from adolescent CIE exposure triggers sigma-1 receptors that act to depress the efficacy of excitatory inputs in triggering

  7. Modulation of neuronal activity in dorsal column nuclei by upper cervical spinal cord stimulation in rats

    PubMed Central

    Qin, Chao; Yang, Xiaoli; Wu, Mingyuan; Farber, Jay P.; Linderoth, Bengt; Foreman, Robert D.

    2009-01-01

    Clinical human and animal studies show that upper cervical spinal cord stimulation (cSCS) has beneficial effects in treatment of some cerebral disorders, including those due to deficient cerebral circulation. However, the underlying mechanisms and neural pathways activated by cSCS using clinical parameters remain unclear. We have shown that a cSCS-induced increase in cerebral blood flow is mediated via rostral spinal dorsal column fibers implying that the dorsal column nuclei (DCNs) are involved. The aim of this study was to examine how cSCS modulated neuronal activity of DCNs.. A spring-loaded unipolar ball electrode was placed on the left dorsal column at cervical (C2) spinal cord in pentobarbital anesthetized, ventilated and paralyzed male rats. Stimulation with frequencies of 1, 10, 20, 50 Hz (0.2 ms, 10 s) and an intensity of 90% of motor threshold was applied. Extracellular potentials of single neurons in DCNs were recorded and examined for effects of cSCS. In total, 109 neurons in DCNs were isolated and tested for effects of cSCS. Out of these, 56 neurons were recorded from the cuneate nucleus and 53 from the gracile nucleus. Mechanical somatic stimuli altered activity of 87/109 (83.2%) examined neurons. Of the neurons receiving somatic input, 62 were classified as low-threshold and 25 as wide dynamic range. The cSCS at 1 Hz changed the activity of 96/109 (88.1%) of the neurons. Neuronal responses to cSCS exhibited multiple patterns of excitation and/or inhibition: excitation (E, n=21), inhibition (I, n=19), E-I (n=37), I-E (n=8) and E-I-E (n=11). Furthermore, cSCS with high-frequency (50 Hz) altered the activity of 92.7% (51/55) of tested neurons, including 30 E, 24 I, and 2 I-E responses to cSCS. These data suggested that cSCS significantly modulates neuronal activity in dorsal column nuclei. These nuclei might serve as a neural relay for cSCS-induced effects on cerebral dysfunction and diseases. PMID:19665525

  8. Neuronal activity causes rapid changes of lateral amygdala neuronal membrane properties and reduction of synaptic integration and synaptic plasticity in vivo

    PubMed Central

    Rosenkranz, J. Amiel

    2011-01-01

    Neuronal membrane properties dictate neuronal responsiveness. Plasticity of membrane properties alters neuronal function and can arise in response to robust neuronal activity. Despite the potential for great impact, there is little evidence for a rapid effect of activity-dependent changes of membrane properties on many neuronal functions in vivo in mammalian brain. In this study it was tested whether periods of neuronal firing lead to a rapid change of membrane properties in neurons of a rat brain region important for some forms of learning, the lateral nucleus of the amygdala (LAT), using in vivo intracellular recordings. Our results demonstrate that rapid plasticity of membrane properties occurs in vivo, in response to action potential firing. This plasticity of membrane properties leads to changes of synaptic integration and subsequent synaptic plasticity. These changes require Ca2+, but are NMDA independent. Furthermore, the parameters and timecourse of these changes would not have been predicted from most in vitro studies. The plasticity of membrane properties demonstrated here may represent a basic form of in vivo short-term plasticity that modifies neuronal function. PMID:21508236

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

    PubMed Central

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

    2016-01-01

    The larval brain of Drosophila melanogaster provides an excellent system for the study of the neurocircuitry mechanism of memory. Recent development of neurogenetic techniques in fruit flies enables manipulations of neuronal activities in freely behaving animals. This protocol describes detailed steps for artificial induction of olfactory associative memory in Drosophila larvae. In this protocol, the natural reward signal is substituted by thermogenetic activation of octopaminergic neurons in the brain. In parallel, the odor signal is substituted by optogenetic activation of a specific class of olfactory receptor neurons. Association of reward and odor stimuli is achieved with the concomitant application of blue light and heat that leads to activation of both sets of neurons in living transgenic larvae. Given its operational simplicity and robustness, this method could be utilized to further our knowledge on the neurocircuitry mechanism of memory in the fly brain. PMID:27445732

  10. NR2D-containing NMDA receptors mediate tissue plasminogen activator-promoted neuronal excitotoxicity.

    PubMed

    Baron, A; Montagne, A; Cassé, F; Launay, S; Maubert, E; Ali, C; Vivien, D

    2010-05-01

    Although the molecular bases of its actions remain debated, tissue-type plasminogen activator (tPA) is a paradoxical brain protease, as it favours some learning/memory processes, but increases excitotoxic neuronal death. Here, we show that, in cultured cortical neurons, tPA selectively promotes NR2D-containing N-methyl-D-aspartate receptor (NMDAR)-dependent activation. We show that tPA-mediated signalling and neurotoxicity through the NMDAR are blocked by co-application of an NR2D antagonist (phenanthrene derivative (2S(*), 3R(*))-1-(phenanthrene-2-carbonyl)piperazine-2,3-dicarboxylic acid, PPDA) or knockdown of neuronal NR2D expression. In sharp contrast with cortical neurons, hippocampal neurons do not exhibit NR2D both in vitro and in vivo and are consequently resistant to tPA-promoted NMDAR-mediated neurotoxicity. Moreover, we have shown that activation of synaptic NMDAR prevents further tPA-dependent NMDAR-mediated neurotoxicity and sensitivity to PPDA. This study shows that the earlier described pro-neurotoxic effect of tPA is mediated by NR2D-containing NMDAR-dependent extracellular signal-regulated kinase activation, a deleterious effect prevented by synaptic pre-activation.

  11. DOC2B and Munc13-1 Differentially Regulate Neuronal Network Activity

    PubMed Central

    Lavi, Ayal; Sheinin, Anton; Shapira, Ronit; Zelmanoff, Daniel; Ashery, Uri

    2014-01-01

    Alterations in the levels of synaptic proteins affect synaptic transmission and synaptic plasticity. However, the precise effects on neuronal network activity are still enigmatic. Here, we utilized microelectrode array (MEA) to elucidate how manipulation of the presynaptic release process affects the activity of neuronal networks. By combining pharmacological tools and genetic manipulation of synaptic proteins, we show that overexpression of DOC2B and Munc13-1, proteins known to promote vesicular maturation and release, elicits opposite effects on the activity of the neuronal network. Although both cause an increase in the overall number of spikes, the distribution of spikes is different. While DOC2B enhances, Munc13-1 reduces the firing rate within bursts of spikes throughout the network; however, Munc13-1 increases the rate of network bursts. DOC2B's effects were mimicked by Strontium that elevates asynchronous release but not by a DOC2B mutant that enhances spontaneous release rate. This suggests for the first time that increased asynchronous release on the single-neuron level promotes bursting activity in the network level. This innovative study demonstrates the complementary role of the network level in explaining the physiological relevance of the cellular activity of presynaptic proteins and the transformation of synaptic release manipulation from the neuron to the network level. PMID:23537531

  12. Influence of spaceflight on succinate dehydrogenase activity and soma size of rat ventral horn neurons

    NASA Technical Reports Server (NTRS)

    Ishihara, A.; Ohira, Y.; Roy, R. R.; Nagaoka, S.; Sekiguchi, C.; Hinds, W. E.; Edgerton, V. R.

    1996-01-01

    Succinate dehydrogenase (SDH) activities and soma cross-sectional areas (CSA) of neurons in the dorsolateral region of the ventral horn at the L5 segmental level of the spinal cord in the rat were determined after 14 days of spaceflight and after 9 days of recovery on earth. The results were compared to those in age-matched ground-based control rats. Spinal cords were quick-frozen, and the SDH activity and CSA of a sample of neurons with a visible nucleus were determined using a digitizer and a computer-assisted image analysis system. An inverse relationship between CSA and SDH activity of neurons was observed in all groups of rats. No change in mean CSA or mean SDH activity or in the size distribution of neurons was observed following spaceflight or recovery. However, there was a selective decrease in the SDH activity of neurons with soma CSA between 500 and 800 microns2 in the flight rats, and this effect persisted for at least 9 days following return to 1 g. It remains to be determined whether the selected population of motoneurons or the specific motor pools affected by spaceflight may be restricted to specific muscles.

  13. Active 3-D microscaffold system with fluid perfusion for culturing in vitro neuronal networks.

    PubMed

    Rowe, Laura; Almasri, Mahmoud; Lee, Kil; Fogleman, Nick; Brewer, Gregory J; Nam, Yoonkey; Wheeler, Bruce C; Vukasinovic, Jelena; Glezer, Ari; Frazier, A Bruno

    2007-04-01

    This work demonstrated the design, fabrication, packaging, and characterization of an active microscaffold system with fluid perfusion/nutrient delivery functionalities for culturing in vitro neuronal networks from dissociated hippocampal rat pup neurons. The active microscaffold consisted of an 8 x 8 array of hollow, microfabricated, SU-8 towers (1.0 mm or 1.5 mm in height), with integrated, horizontal, SU-8 cross-members that connect adjacent towers, thus forming a 3-D grid that is conducive to branching, growth, and increased network formation of dissociated hippocampal neurons. Each microtower in the microscaffold system contained a hollow channel and multiple fluid ports for media delivery and perfusion of nutrients to the in vitro neuronal network growing within the microscaffold system. Additionally, there were two exposed Au electrodes on the outer wall of each microtower at varying heights (with insulated leads running within the microtower walls), which will later allow for integration of electrical stimulation/recording functionalities into the active microscaffold system. However, characterization of the stimulation/recording electrodes was not included in the scope of this paper. Design, fabrication, fluid packaging, and characterization of the active microscaffold system were performed. Furthermore, use of the active microscaffold system was demonstrated by culturing primary hippocampal embryonic rat pup neurons, and characterizing cell viability within the microscaffold system.

  14. Importance of rostral ventrolateral medulla neurons in determining efferent sympathetic nerve activity and blood pressure.

    PubMed

    Kumagai, Hiroo; Oshima, Naoki; Matsuura, Tomokazu; Iigaya, Kamon; Imai, Masaki; Onimaru, Hiroshi; Sakata, Katsufumi; Osaka, Motohisa; Onami, Toshiko; Takimoto, Chie; Kamayachi, Tadashi; Itoh, Hiroshi; Saruta, Takao

    2012-02-01

    Accentuated sympathetic nerve activity (SNA) is a risk factor for cardiovascular events. In this review, we investigate our working hypothesis that potentiated activity of neurons in the rostral ventrolateral medulla (RVLM) is the primary cause of experimental and essential hypertension. Over the past decade, we have examined how RVLM neurons regulate peripheral SNA, how the sympathetic and renin-angiotensin systems are correlated and how the sympathetic system can be suppressed to prevent cardiovascular events in patients. Based on results of whole-cell patch-clamp studies, we report that angiotensin II (Ang II) potentiated the activity of RVLM neurons, a sympathetic nervous center, whereas Ang II receptor blocker (ARB) reduced RVLM activities. Our optical imaging demonstrated that a longitudinal rostrocaudal column, including the RVLM and the caudal end of ventrolateral medulla, acts as a sympathetic center. By organizing and analyzing these data, we hope to develop therapies for reducing SNA in our patients. Recently, 2-year depressor effects were obtained by a single procedure of renal nerve ablation in patients with essential hypertension. The ablation injured not only the efferent renal sympathetic nerves but also the afferent renal nerves and led to reduced activities of the hypothalamus, RVLM neurons and efferent systemic sympathetic nerves. These clinical results stress the importance of the RVLM neurons in blood pressure regulation. We expect renal nerve ablation to be an effective treatment for congestive heart failure and chronic kidney disease, such as diabetic nephropathy.

  15. Orientation-dependent changes in single motor neuron activity during adaptive soft-bodied locomotion.

    PubMed

    Metallo, Cinzia; Trimmer, Barry A

    2015-01-01

    Recent major advances in understanding the organizational principles underlying motor control have focused on a small number of animal species with stiff articulated skeletons. These model systems have the advantage of easily quantifiable mechanics, but the neural codes underlying different movements are difficult to characterize because they typically involve a large population of neurons controlling each muscle. As a result, studying how neural codes drive adaptive changes in behavior is extremely challenging. This problem is highly simplified in the tobacco hawkmoth Manduca sexta, which, in its larval stage (caterpillar), is predominantly soft-bodied. Since each M. sexta muscle is innervated by one, occasionally two, excitatory motor neurons, the electrical activity generated by each muscle can be mapped to individual motor neurons. In the present study, muscle activation patterns were converted into motor neuron frequency patterns by identifying single excitatory junction potentials within recorded electromyographic traces. This conversion was carried out with single motor neuron resolution thanks to the high signal selectivity of newly developed flexible microelectrode arrays, which were specifically designed to record from M. sexta muscles. It was discovered that the timing of motor neuron activity and gait kinematics depend on the orientation of the plane of motion during locomotion. We report that, during climbing, the motor neurons monitored in the present study shift their activity to correlate with movements in the animal's more anterior segments. This orientation-dependent shift in motor activity is in agreement with the expected shift in the propulsive forces required for climbing. Our results suggest that, contrary to what has been previously hypothesized, M.sexta uses central command timing for adaptive load compensation.

  16. Modelling the Effects of Electrical Coupling between Unmyelinated Axons of Brainstem Neurons Controlling Rhythmic Activity

    PubMed Central

    Hull, Michael J.; Soffe, Stephen R.; Willshaw, David J.; Roberts, Alan

    2015-01-01

    Gap junctions between fine unmyelinated axons can electrically couple groups of brain neurons to synchronise firing and contribute to rhythmic activity. To explore the distribution and significance of electrical coupling, we modelled a well analysed, small population of brainstem neurons which drive swimming in young frog tadpoles. A passive network of 30 multicompartmental neurons with unmyelinated axons was used to infer that: axon-axon gap junctions close to the soma gave the best match to experimentally measured coupling coefficients; axon diameter had a strong influence on coupling; most neurons were coupled indirectly via the axons of other neurons. When active channels were added, gap junctions could make action potential propagation along the thin axons unreliable. Increased sodium and decreased potassium channel densities in the initial axon segment improved action potential propagation. Modelling suggested that the single spike firing to step current injection observed in whole-cell recordings is not a cellular property but a dynamic consequence of shunting resulting from electrical coupling. Without electrical coupling, firing of the population during depolarising current was unsynchronised; with coupling, the population showed synchronous recruitment and rhythmic firing. When activated instead by increasing levels of modelled sensory pathway input, the population without electrical coupling was recruited incrementally to unpatterned activity. However, when coupled, the population was recruited all-or-none at threshold into a rhythmic swimming pattern: the tadpole “decided” to swim. Modelling emphasises uncertainties about fine unmyelinated axon physiology but, when informed by biological data, makes general predictions about gap junctions: locations close to the soma; relatively small numbers; many indirect connections between neurons; cause of action potential propagation failure in fine axons; misleading alteration of intrinsic firing

  17. Hyperpolarization-activated cyclic nucleotide-gated channels in mouse vomeronasal sensory neurons.

    PubMed

    Dibattista, Michele; Mazzatenta, Andrea; Grassi, Francesca; Tirindelli, Roberto; Menini, Anna

    2008-08-01

    Hyperpolarization-activated currents (Ih) are present in several neurons of the central and peripheral nervous system. However, Ih in neurons of the vomeronasal organ (VNO) is not well characterized. We studied the properties of Ih in sensory neurons from acute slices of mouse VNO. In voltage-clamp studies, Ih was identified by the characteristic kinetics of activation, voltage dependence, and blockage by Cs+ or ZD-7288, two blockers of the Ih. Forskolin, an activator of adenylyl cyclase, shifted the activation curve for Ih to less negative potentials. A comparison of Ih properties in VNO neurons with those of heterologously expressed hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, together with RT-PCR experiments in VNO, indicate that Ih is caused by HCN2 and/or HCN4 subunits. In current-clamp recordings, blocking Ih with ZD-7288 induced a hyperpolarization of 5.1 mV, an increase in input resistance, a decrease in the sensitivity to elicit action potentials in response to small current injections, and did not modify the frequency of action potentials elicited by a large current injection. It has been shown that in VNO neurons some pheromones induce a decrease in cAMP concentration, but the physiological role of cAMP is unknown. After application of blockers of adenylyl cyclase, we measured a hyperpolarization of 5.1 mV in 11 of 14 neurons, suggesting that basal levels of cAMP could modulate the resting potential. In conclusion, these results show that mouse VNO neurons express HCN2 and/or HCN4 subunits and that Ih contributes to setting the resting membrane potential and to increase excitability at stimulus threshold.

  18. A quantitative analytic pipeline for evaluating neuronal activities by high throughput synaptic vesicle imaging

    PubMed Central

    Fan, Jing; Xia, Xiaofeng; Li, Ying; Dy, Jennifer G.

    2012-01-01

    Synaptic vesicle dynamics play an important role in the study of neuronal and synaptic activities of neurodegradation diseases ranging from the epidemic Alzheimer’s disease to the rare Rett syndrome. A high-throughput assay with a large population of neurons would be useful and efficient to characterize neuronal activity based on the dynamics of synaptic vesicles for the study of mechanisms or to discover drug candidates for neurodegenerative and neurodevelopmental disorders. However, the massive amounts of image data generated via high throughput screening require enormous manual processing time and effort, restricting the practical use of such an assay. This paper presents an automated analytic system to process and interpret the huge data set generated by such assays. Our system enables the automated detection, segmentation, quantification, and measurement of neuron activities based on the synaptic vesicle assay. To overcome challenges such as noisy background, inhomogeneity, and tiny object size, we first employ MSVST (Multi-Scale Variance Stabilizing Transform) to obtain a denoised and enhanced map of the original image data. Then, we propose an adaptive thresholding strategy to solve the inhomogeneity issue, based on the local information, and to accurately segment synaptic vesicles. We design algorithms to address the issue of tiny objects-of-interest overlapping. Several post-processing criteria are defined to filter false positives. A total of 152 features are extracted for each detected vesicle. A score is defined for each synaptic vesicle image to quantify the neuron activity. We also compare the unsupervised strategy with the supervised method. Our experiments on hippocampal neuron assays showed that the proposed system can automatically detect vesicles and quantify their dynamics for evaluating neuron activities. The availability of such an automated system will open opportunities for investigation of synaptic neuropathology and identification of

  19. Cingulate seizure-like activity reveals neuronal avalanche regulated by network excitability and thalamic inputs

    PubMed Central

    2014-01-01

    Background Cortical neurons display network-level dynamics with unique spatiotemporal patterns that construct the backbone of processing information signals and contribute to higher functions. Recent years have seen a wealth of research on the characteristics of neuronal networks that are sufficient conditions to activate or cease network functions. Local field potentials (LFPs) exhibit a scale-free and unique event size distribution (i.e., a neuronal avalanche) that has been proven in the cortex across species, including mice, rats, and humans, and may be used as an index of cortical excitability. In the present study, we induced seizure activity in the anterior cingulate cortex (ACC) with medial thalamic inputs and evaluated the impact of cortical excitability and thalamic inputs on network-level dynamics. We measured LFPs from multi-electrode recordings in mouse cortical slices and isoflurane-anesthetized rats. Results The ACC activity exhibited a neuronal avalanche with regard to avalanche size distribution, and the slope of the power-law distribution of the neuronal avalanche reflected network excitability in vitro and in vivo. We found that the slope of the neuronal avalanche in seizure-like activity significantly correlated with cortical excitability induced by γ-aminobutyric acid system manipulation. The thalamic inputs desynchronized cingulate seizures and affected the level of cortical excitability, the modulation of which could be determined by the slope of the avalanche size. Conclusions We propose that the neuronal avalanche may be a tool for analyzing cortical activity through LFPs to determine alterations in network dynamics. PMID:24387299

  20. An addressable confocal microscope for functional imaging of neuronal activity

    NASA Astrophysics Data System (ADS)

    Bansal, Vivek

    2005-07-01

    The study of computation occurring in single neurons and small networks of interconnected neurons is often limited by (1) the number of sites that can be simultaneously probed with electrophysiology tools such as patch pipettes and (2) the recording speed of fluorescence imaging tools such as confocal or multiphoton microscopy. Even in the line scan mode of galvanometer-based scanners, where one scan dimension is sacrificed to gain overall speed, the effective frame rate is limited to less than 1 kHz with no flexibility in site selection. To overcome these limitations and allow the study of many sites throughout the dendritic arbor, we have developed an addressable confocal laser-scanning microscope that permits recording from user-selected sites-of-interest at high frame rates, in addition to conventional full frame imaging. Our system utilizes acousto-optic deflectors (AODs) in the illumination pathway to allow for rapid user-defined positioning of a focused laser spot. However, since AODs rely on diffraction to steer a laser beam, they cannot effectively descan the fluorescence emission spectrum as done in mirror-based systems which utilize reflection; this prevents the use of a stationary pinhole as a spatial filter. Instead, we implement an addressable spatial filter using a digital micromirror device (DMD) in conjunction with the AODs to achieve confocality. A registration algorithm synchronizes the AODs and DMD such that point illumination and point detection are always colocalized in conjugate image planes. The current version of the confocal system has a spatial resolution of ˜1 mum. Furthermore, by letting the user tailor which sites are visited, we have shown that recordings can be made at an aggregate frame rate of ˜40 kHz. We have successfully demonstrated that the system is capable of optical sectioning and thus exhibits the main advantage of a confocal microscope for light-scattering biological tissue. This property was used to create three

  1. Alpha 2-adrenergic receptors influence tyrosine hydroxylase activity in retinal dopamine neurons.

    PubMed

    Iuvone, P M; Rauch, A L

    1983-12-12

    Dopamine (DA) is a putative neurotransmitter in a population of interneurons in the mammalian retina that are activated by photic stimulation. Pharmacological studies were conducted to determine if alpha 2-adrenergic receptors influence the activity of retinal tyrosine hydroxylase (TH), a biochemical indicator of changes in the activity of the DA-containing neurons. TH activity was low in dark-adapted retinas and high in light-exposed retinas. Systemic administration of the alpha 2-adrenoceptor antagonists, yohimbine and piperoxane, to dark-adapted rats significantly stimulated TH activity. This effect was apparently mediated locally within the retina because the response could also be elicited by direct injection of yohimbine into the vitreous. The dose-response relationships for the effects of alpha 2-adrenoceptor antagonists on retinal TH activity were similar to those for the effects on brain noradrenergic neurons, where alpha 2-adrenoceptors have been shown to be involved in the autoregulation of neuronal activity. Clonidine, an alpha 2-adrenoceptor agonist, had no effect when administered alone to dark-adapted rats, but it attenuated the stimulatory effect of yohimbine. In contrast, clonidine decreased TH activity of light-exposed retinas, an effect that was reversed by yohimbine. These observations suggest that alpha 2-adrenoceptors influence the activity of retinal DA-containing neurons.

  2. Increased food intake in growth hormone-transgenic common carp (Cyprinus carpio L.) may be mediated by upregulating Agouti-related protein (AgRP).

    PubMed

    Zhong, Chengrong; Song, Yanlong; Wang, Yaping; Zhang, Tanglin; Duan, Ming; Li, Yongming; Liao, Lanjie; Zhu, Zuoyan; Hu, Wei

    2013-10-01

    In fish, food intake and feeding behavior are crucial for survival, competition, growth and reproduction. Growth hormone (GH)-transgenic common carp exhibit an enhanced growth rate, increased food intake and higher feed conversion rate. However, the underlying molecular mechanisms of feeding regulation in GH-transgenic (TG) fish are not clear. In this study, we observed feeding behavior of TG and non-transgenic (NT) common carp, and analyzed the mRNA expression levels of NPY, AgRP I, orexin, POMC, CCK, and CART I in the hypothalamus and telencephalon after behavioral observation. We detected similar gene expression levels in the hypothalamus of TG and NT common carp, which had been cultured in the field at the same age. Furthermore, we tested the effects of GH on hypothalamus fragments in vitro to confirm our findings. We demonstrated that TG common carp displayed increased food intake and reduced food consumption time, which were associated with a marked increase in hypothalamic AgRP I mRNA expression. Our results suggest that elevated GH levels may influence food intake and feeding behavior by upregulating the hypothalamic orexigenic factor AgRP I in GH-transgenic common carp.

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  4. Caspase-3 activation and DNA fragmentation in primary hippocampal neurons following glutamate excitotoxicity.

    PubMed

    Brecht, S; Gelderblom, M; Srinivasan, A; Mielke, K; Dityateva, G; Herdegen, T

    2001-10-19

    Excitotoxic glutamate CNS stimulation can result in neuronal cell death. Contributing mechanisms and markers of cell death are the activation of caspase-3 and DNA fragmentation. It remains to be resolved to which extent both cellular reactions overlap and/or indicate different processes of neurodegeneration. In this study, mixed neuronal cultures from newborn mice pubs (0-24 h) were stimulated with glutamate, and the co-localization of active caspase-3 and DNA fragmentation was investigated by immunocytochemistry and the TUNEL nick-end labelling. In untreated cultures, 8% scattered neurons (marked by MAP-2) displayed activated caspase-3 at different morphological stages of degeneration. TUNEL staining was detected in 5% of cell nuclei including GFAP-positive astrocytes. However, co-localization of active caspase-3 with TUNEL was less than 2%. After glutamate stimulation (125 microM), the majority of neurons was dying between 12 and 24 h. The absolute number of active caspase-3 neurons increased only moderately but in relation of surviving neurons after 24 h from 8 to 36% (125 microM), to 53% (250 microM) or to 32% (500 microM). TUNEL staining also increased after 24 h following glutamate treatment to 37% but the co-localization with active caspase-3 remained at the basal low level of 2%. In our system, glutamate-mediated excitotoxicity effects the DNA fragmentation and caspase-3 activation. Co-localization of both parameters, however, is very poor. Active caspase-3 in the absence of TUNEL indicates a dynamic degenerative process, whereas TUNEL marks the end stage of severe irreversible cell damage regardless to the origin of the cell.

  5. Locus coeruleus neuronal activity during the sleep-waking cycle in mice.

    PubMed

    Takahashi, K; Kayama, Y; Lin, J S; Sakai, K

    2010-09-01

    Using extracellular single-unit recordings in nonanesthetized, head-restrained mice, we examined spontaneous and evoked discharges of noradrenaline-containing locus coeruleus (NA-LC) neurons across the sleep-waking cycle. The neurons were all characterized by triphasic broad action potentials. They discharged as either slow (<6 Hz) tonic, single spikes or phasic clusters of spikes specific to wakefulness (W), the discharge rate being highest during active waking and significantly lower during quiet waking. They remained totally silent during both slow-wave sleep (SWS) and paradoxical (or rapid eye movement (REM)) sleep. The phasic unit activity was related to abrupt activation of electromyographic activity occurring either spontaneously or elicited by alerting sensory stimuli. At the transition from waking to sleep, they ceased firing before the onset of cortical synchronization (deactivation), the first sign of electroencephalographic sleep, a significant decrease in firing rate preceding the onset of unit activity of sleep-specific neurons in the basal forebrain (BFB)/preoptic (POA) hypothalamus, as described previously [Takahashi K, Lin JS, Sakai K (2009) Neuroscience 161:269-292]. At the transition from SWS to waking, they fired before the onset of both cortical activation and a significant decrease in activity of sleep-specific neurons. These findings support the previous view that the NA-LC system is involved in both tonic and phasic processes of arousal, and further support our previous proposals that initiation of sleep is caused by decreased activity of waking-promoting neurons (disfacilitation) and that NA-LC neurons play an important role in the sleep/waking switch, that is from waking to sleep and from sleep to waking [Takahashi K, Lin JS, Sakai K (2009) Neuroscience 161:269-292].

  6. Visual input controls the functional activity of goldfish Mauthner neuron through the reciprocal synaptic mechanism.

    PubMed

    Moshkov, Dmitry A; Shtanchaev, Rashid S; Mikheeva, Irina B; Bezgina, Elena N; Kokanova, Nadezhda A; Mikhailova, Gulnara Z; Tiras, Nadezhda R; Pavlik, Lyubov' L

    2013-03-01

    Goldfish are known to exhibit motor asymmetry due to functional asymmetry of their Mauthner neurons that induce the turns to the right or left during free swimming. It has been previously found that if the less active neuron is subjected to prolonged aimed visual stimulation via its ventral dendrite, the motor asymmetry of goldfish is inverted, testifying that this neuron becomes functionally dominant, while the size of the ventral dendrite under these conditions is reduced 2-3 times compared to its counterpart in mirror neuron. Earlier it has been also revealed that training optokinetic stimulation induces adaptation, a substantial resistance of both fish motor asymmetry and morphofunctional state of Mauthner neurons against prolonged optokinetic stimulation. The aim of this work was to study the cellular mechanisms of the effect of an unusual visual afferent input on goldfish motor asymmetry and Mauthner neuron function in norm and under adaptation. It was shown that serotonin applied onto Mauthner neurons greatly reduces their activity whereas its antagonist ondansetron increases it. Against the background of visual stimulation, serotonin strengthens functional asymmetry between neurons whereas ondansetron smoothes it. Taken together these data suggest the involvement of serotonergic excitatory synaptic transmission in the regulation of Mauthner neurons by vision. Ultrastructural study of the ventral dendrites after prolonged optokinetic stimulation has revealed depletions of numeral axo-axonal synapses with specific morphology, identified by means of immunogold label as serotonergic ones. These latter in turn are situated mainly on shaft boutons, which according to specific ultrastructural features are assigned to axo-dendritic inhibitory synapses. Thus, the excitatory serotonergic synapses seem to affect Mauthner neuron indirectly through inhibitory synapses. Further, it was morphometrically established that adaptation is accompanied by the significant

  7. Activation of dopamine neurons is critical for aversive conditioning and prevention of generalized anxiety.

    PubMed

    Zweifel, Larry S; Fadok, Jonathan P; Argilli, Emmanuela; Garelick, Michael G; Jones, Graham L; Dickerson, Tavis M K; Allen, James M; Mizumori, Sheri J Y; Bonci, Antonello; Palmiter, Richard D

    2011-05-01

    Generalized anxiety is thought to result, in part, from impairments in contingency awareness during conditioning to cues that predict aversive or fearful outcomes. Dopamine neurons of the ventral midbrain exhibit heterogeneous responses to aversive stimuli that are thought to provide a critical modulatory signal to facilitate orientation to environmental changes and assignment of motivational value to unexpected events. Here we describe a mouse model in which activation of dopamine neurons in response to an aversive stimulus is attenuated by conditional genetic inactivation of functional NMDA receptors on dopamine neurons. We discovered that altering the magnitude of excitatory responses by dopamine neurons in response to an aversive stimulus was associated with impaired conditioning to a cue that predicts an aversive outcome. Impaired conditioning by these mice was associated with the development of a persistent, generalized anxiety-like phenotype. These data are consistent with a role for dopamine in facilitating contingency awareness that is critical for the prevention of generalized anxiety.

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

    PubMed Central

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

    2016-01-01

    Adiponectin regulates glucose and lipid metabolism, acting against metabolic syndrome and atherosclerosis. Accumulating evidence suggest that adiponectin acts on the brain including hypothalamic arcuate nucleus (ARC), where proopiomelanocortin (POMC) neurons play key roles in feeding regulation. Several studies have examined intracerebroventricular (ICV) injection of adiponectin and reported opposite effects, increase or decrease of food intake. These reports used different nutritional states. The present study aimed to clarify whether adiponectin exerts distinct effects on food intake and ARC POMC neurons depending on the glucose concentration. Adiponectin was ICV injected with or without glucose for feeding experiments and administered to ARC slices with high or low glucose for patch clamp experiments. We found that adiponectin at high glucose inhibited POMC neurons and increased food intake while at low glucose it exerted opposite effects. The results demonstrate that glucose level determines excitatory or inhibitory effects of adiponectin on arcuate POMC neuron activity and feeding. PMID:27503800

  9. Calcium-activated chloride channels as a new target to control the spiking pattern of neurons.

    PubMed

    Ha, Go Eun; Cheong, Eunji

    2017-03-03

    Neuronal firing patterns and frequencies determine the nature of encoded information in the neural circuits. Here we discuss the molecular identity and cellular mechanisms of spike-frequency adaptation in central nervous system (CNS). Spike-frequency adaptation in thalamocortical (TC) and CA1 hippocampal neurons is mediated by the Ca2+-activated Cl- channel (CACC) anoctamin-2 (ANO2). Knockdown of ANO2 in these neurons results in significantly reduced spike-frequency adaptation along with increased number of spikes. No previous study has described the finding that CACCs mediate afterhyperpolarization currents, which result in the modulation of neuronal spike patterns in the central nervous system. Therefore, our study proposes a novel role for ANO2 in spike-frequency adaptation and transmission of information in the brain.

  10. Effects of Calcium Spikes in the Layer 5 Pyramidal Neuron on Coincidence Detection and Activity Propagation

    PubMed Central

    Chua, Yansong; Morrison, Abigail

    2016-01-01

    The role of dendritic spiking mechanisms in neural processing is so far poorly understood. To investigate the role of calcium spikes in the functional properties of the single neuron and recurrent networks, we investigated a three compartment neuron model of the layer 5 pyramidal neuron with calcium dynamics in the distal compartment. By performing single neuron simulations with noisy synaptic input and occasional large coincident input at either just the distal compartment or at both somatic and distal compartments, we show that the presence of calcium spikes confers a substantial advantage for coincidence detection in the former case and a lesser advantage in the latter. We further show that the experimentally observed critical frequency phenomenon, in which action potentials triggered by stimuli near the soma above a certain frequency trigger a calcium spike at distal dendrites, leading to further somatic depolarization, is not exhibited by a neuron receiving realistically noisy synaptic input, and so is unlikely to be a necessary component of coincidence detection. We next investigate the effect of calcium spikes in propagation of spiking activities in a feed-forward network (FFN) embedded in a balanced recurrent network. The excitatory neurons in the network are again connected to either just the distal, or both somatic and distal compartments. With purely distal connectivity, activity propagation is stable and distinguishable for a large range of recurrent synaptic strengths if the feed-forward connections are sufficiently strong, but propagation does not occur in the absence of calcium spikes. When connections are made to both the somatic and the distal compartments, activity propagation is achieved for neurons with active calcium dynamics at a much smaller number of neurons per pool, compared to a network of passive neurons, but quickly becomes unstable as the strength of recurrent synapses increases. Activity propagation at higher scaling factors can be

  11. Effects of Calcium Spikes in the Layer 5 Pyramidal Neuron on Coincidence Detection and Activity Propagation.

    PubMed

    Chua, Yansong; Morrison, Abigail

    2016-01-01

    The role of dendritic spiking mechanisms in neural processing is so far poorly understood. To investigate the role of calcium spikes in the functional properties of the single neuron and recurrent networks, we investigated a three compartment neuron model of the layer 5 pyramidal neuron with calcium dynamics in the distal compartment. By performing single neuron simulations with noisy synaptic input and occasional large coincident input at either just the distal compartment or at both somatic and distal compartments, we show that the presence of calcium spikes confers a substantial advantage for coincidence detection in the former case and a lesser advantage in the latter. We further show that the experimentally observed critical frequency phenomenon, in which action potentials triggered by stimuli near the soma above a certain frequency trigger a calcium spike at distal dendrites, leading to further somatic depolarization, is not exhibited by a neuron receiving realistically noisy synaptic input, and so is unlikely to be a necessary component of coincidence detection. We next investigate the effect of calcium spikes in propagation of spiking activities in a feed-forward network (FFN) embedded in a balanced recurrent network. The excitatory neurons in the network are again connected to either just the distal, or both somatic and distal compartments. With purely distal connectivity, activity propagation is stable and distinguishable for a large range of recurrent synaptic strengths if the feed-forward connections are sufficiently strong, but propagation does not occur in the absence of calcium spikes. When connections are made to both the somatic and the distal compartments, activity propagation is achieved for neurons with active calcium dynamics at a much smaller number of neurons per pool, compared to a network of passive neurons, but quickly becomes unstable as the strength of recurrent synapses increases. Activity propagation at higher scaling factors can be

  12. Antipsychotics Activate mTORC1-Dependent Translation to Enhance Neuronal Morphological Complexity

    PubMed Central

    Bowling, Heather; Zhang, Guoan; Bhattacharya, Aditi; Pérez-Cuesta, Luis M.; Deinhardt, Katrin; Hoeffer, Charles A.; Neubert, Thomas A.; Gan, Wen-biao; Klann, Eric; Chao, Moses V.

    2014-01-01

    Although antipsychotic drugs can reduce psychotic behavior within a few hours, full efficacy is not achieved for several weeks, implying that there may be rapid, short-term changes in neuronal function, which are consolidated into long-lasting changes. Here, we showed that the antipsychotic drug haloperidol, a dopamine receptor type 2 (D2R) antagonist, stimulated the kinase Akt to activate the mRNA translation pathway mediated by the mammalian target of rapamycin complex 1 (mTORC1). In primary striatal D2R-positive neurons, haloperidol-mediated activation of mTORC1 resulted in increased phosphorylation of ribosomal protein S6 (S6) and eukaryotic translation initiation factor 4E-binding protein (4E-BP). Proteomic mass spectrometry revealed marked changes in the pattern of protein synthesis after acute exposure of cultured striatal neurons to haloperidol, including increased abundance of cytoskeletal proteins and proteins associated with translation machinery. These proteomic changes coincided with increased morphological complexity of neurons that was diminished by inhibition of downstream effectors of mTORC1, suggesting that mTORC1-dependent translation enhances neuronal complexity in response to haloperidol. In vivo, we observed rapid morphological changes with a concomitant increase in the abundance of cytoskeletal proteins in cortical neurons of haloperidol-injected mice. These results suggest a mechanism for both the acute and long-term actions of antipsychotics. PMID:24425786

  13. Activation of the type I interferon pathway is enhanced in response to human neuronal differentiation.

    PubMed

    Farmer, Jocelyn R; Altschaefl, Kate M; O'Shea, K Sue; Miller, David J

    2013-01-01

    Despite the crucial role of innate immunity in preventing or controlling pathogen-induced damage in most, if not all, cell types, very little is known about the activity of this essential defense system in central nervous system neurons, especially in humans. In this report we use both an established neuronal cell line model and an embryonic stem cell-based system to examine human neuronal innate immunity and responses to neurotropic alphavirus infection in cultured cells. We demonstrate that neuronal differentiation is associated with increased expression of crucial type I interferon signaling pathway components, including interferon regulatory factor-9 and an interferon receptor heterodimer subunit, which results in enhanced interferon stimulation and subsequent heightened antiviral activity and cytoprotective responses against neurotropic alphaviruses such as western equine encephalitis virus. These results identify important differentiation-dependent changes in innate immune system function that control cell-autonomous neuronal responses. Furthermore, this work demonstrates the utility of human embryonic stem cell-derived cultures as a platform to study the interactions between innate immunity, virus infection, and pathogenesis in central nervous system neurons.

  14. Sensory deprivation increases phagocytosis of adult-born neurons by activated microglia in the olfactory bulb.

    PubMed

    Denizet, Marie; Cotter, Laurent; Lledo, Pierre-Marie; Lazarini, Françoise

    2017-02-01

    The olfactory bulb (OB) is a highly plastic structure that can change organizational networks depending on environmental inputs in adult mammals. Particularly, in rodents, adult neurogenesis underlies plastic changes in the OB circuitry by continuously adding new interneurons to the network. We addressed the question of whether microglia, the immune cells of the brain, were involved in pruning OB neurons. Using lentiviral labeling of neurons in neonatal or adult mice and confocal analysis, we showed that microglia engulfed parts of neonatal-born and adult-born neurons in the healthy OB. We demonstrated that OB deafferentation by Dichlobenil administration induced sensory deprivation. It also increased phagocytosis of adult-born, but not neonatal-born neurons, by activated microglia. Conversely, intranasal lipopolysaccharide administration induced activation of microglia but changed neither adult neurogenesis nor olfaction. Our data reveal that steady-state microglia eliminate adult-born neurons and their synapses in both healthy and sensory deprived OBs, thereby adapting neuronal connections to the sensory experience.

  15. Neuronal activity in primate orbitofrontal cortex reflects the value of time.

    PubMed

    Roesch, Matthew R; Olson, Carl R

    2005-10-01

    Neurons in monkey orbitofrontal cortex (OF) are known to respond to reward-predicting cues with a strength that depends on the value of the predicted reward as determined 1) by intrinsic attributes including size and quality and 2) by extrinsic factors including the monkey's state of satiation and awareness of what other rewards are currently available. We pose here the question whether another extrinsic factor critical to determining reward value-the delay expected to elapse before delivery-influences neuronal activity in OF. To answer this question, we recorded from OF neurons while monkeys performed a memory-guided saccade task in which a cue presented early in each trial predicted whether the delay before the monkey could respond and receive a reward of fixed size would be short or long. OF neurons tended to fire more strongly in response to a cue predicting a short delay. The tendency to fire more strongly in anticipation of a short delay was correlated across neurons with the tendency to fire more strongly before a large reward. We conclude that neuronal activity in OF represents the time-discounted value of the expected reward.

  16. Activity of human hippocampal and amygdala neurons during retrieval of declarative memories.

    PubMed

    Rutishauser, Ueli; Schuman, Erin M; Mamelak, Adam N

    2008-01-08

    Episodic memories allow us to remember not only that we have seen an item before but also where and when we have seen it (context). Sometimes, we can confidently report that we have seen something (familiarity) but cannot recollect where or when it was seen. Thus, the two components of episodic recall, familiarity and recollection, can be behaviorally dissociated. It is not clear, however, whether these two components of memory are represented separately by distinct brain structures or different populations of neurons in a single anatomical structure. Here, we report that the spiking activity of single neurons in the human hippocampus and amygdala [the medial temporal lobe (MTL)] contain information about both components of memory. We analyzed a class of neurons that changed its firing rate to the second presentation of a previously novel stimulus. We found that the neuronal activity evoked by the presentation of a familiar stimulus (during retrieval) distinguishes stimuli that will be successfully recollected from stimuli that will not be recollected. Importantly, the ability to predict whether a stimulus is familiar is not influenced by whether the stimulus will later be recollected. We thus conclude that human MTL neurons contain information about both components of memory. These data support a continuous strength of memory model of MTL function: the stronger the neuronal response, the better the memory.

  17. Stepping Out of the Shade: Control of Neuronal Activity by the Scaffold Protein Kidins220/ARMS

    PubMed Central

    Scholz-Starke, Joachim; Cesca, Fabrizia

    2016-01-01

    The correct functioning of the nervous system depends on the exquisitely fine control of neuronal excitability and synaptic plasticity, which relies on an intricate network of protein-protein interactions and signaling that shapes neuronal homeostasis during development and in adulthood. In this complex scenario, Kinase D interacting substrate of 220 kDa/ankyrin repeat-rich membrane spanning (Kidins220/ARMS) acts as a multi-functional scaffold protein with preferential expression in the nervous system. Engaged in a plethora of interactions with membrane receptors, cytosolic signaling components and cytoskeletal proteins, Kidins220/ARMS is implicated in numerous cellular functions including neuronal survival, neurite outgrowth and maturation and neuronal activity, often in the context of neurotrophin (NT) signaling pathways. Recent studies have highlighted a number of cell- and context-specific roles for this protein in the control of synaptic transmission and neuronal excitability, which are at present far from being completely understood. In addition, some evidence has began to emerge, linking alterations of Kidins220 expression to the onset of various neurodegenerative diseases and neuropsychiatric disorders. In this review, we present a concise summary of our fragmentary knowledge of Kidins220/ARMS biological functions, focusing on the mechanism(s) by which it controls various aspects of neuronal activity. We have tried, where possible, to discuss the available evidence in the wider context of NT-mediated regulation, and to outline emerging roles of Kidins220/ARMS in human pathologies. PMID:27013979

  18. NFκB-inducing kinase inhibits NFκB activity specifically in neurons of the CNS.

    PubMed

    Mao, Xianrong; Phanavanh, Bounleut; Hamdan, Hamdan; Moerman-Herzog, Andréa M; Barger, Steven W

    2016-04-01

    The control of NFκB in CNS neurons appears to differ from that in other cell types. Studies have reported induction of NFκB in neuronal cultures and immunostaining in vivo, but others have consistently detected little or no transcriptional activation by NFκB in brain neurons. To test if neurons lack some component of the signal transduction system for NFκB activation, we transfected cortical neurons with several members of this signaling system along with a luciferase-based NFκB-reporter plasmid; RelA was cotransfected in some conditions. No component of the NFκB pathway was permissive for endogenous NFκB activity, and none stimulated the activity of exogenous RelA. Surprisingly, however, the latter was inhibited by cotransfection of NFκB-inducing kinase (NIK). Fluorescence imaging of RelA indicated that co-expression of NIK sequestered RelA in the cytoplasm, similar to the effect of IκBα. NIK-knockout mice showed elevated expression of an NFκB-reporter construct in neurons in vivo. Cortical neurons cultured from NIK-knockout mice showed elevated expression of an NFκB-reporter transgene. Consistent with data from other cell types, a C-terminal fragment of NIK suppressed RelA activity in astrocytes as well as neurons. Therefore, the inhibitory ability of the NIK C-terminus was unbiased with regard to cell type. However, inhibition of NFκB by full-length NIK is a novel outcome that appears to be specific to CNS neurons. This has implications for unique aspects of transcription in the CNS, perhaps relevant to aspects of development, neuroplasticity, and neuroinflammation. Full-length NIK was found to inhibit (down arrow) transcriptional activation of NFκB in neurons, while it elevated (up arrow) activity in astrocytes. Deletion constructs corresponding to the N-terminus or C-terminus also inhibited NFκB in neurons, while only the C-terminus did so in astrocytes. One possible explanation is that the inhibition in neurons occurs via two different

  19. Depolarising and hyperpolarising actions of GABAA receptor activation on GnRH neurons: towards an emerging consensus

    PubMed Central

    Herbison, Allan E.; Moenter, Suzanne M.

    2011-01-01

    The gonadotropin-releasing hormone (GnRH) neurons represent the final output neurons of a complex neuronal network that controls fertility. It is now appreciated that GABAergic neurons within this network provide an important regulatory influence on GnRH neurons. However, the consequences of direct GABAA receptor activation on adult GnRH neurons have been controversial for nearly a decade now, with both hyperpolarising and depolarising effects reported. This review provides (i) an overview of GABAA receptor function and its investigation using electrophysiological approaches and (ii) re-examines the past and present results relating to GABAergic regulation of the GnRH neuron, with a focus on mouse brain slice data. Although it remains difficult to reconcile the results of the early studies, there is a growing consensus that GABA can act through the GABAA receptor to exert both depolarising and hyperpolarising effects on GnRH neurons. The most recent studies examining the effects of endogenous GABA release on GnRH neurons indicate that the predominant action is that of excitation. However, we are still far from a complete understanding of the effects of GABAA receptor activation upon GnRH neurons. We argue that this will require not only a better understanding of chloride ion homeostasis in individual GnRH neurons, and within subcellular compartments of the GnRH neuron, but also a more integrative view of how multiple neurotransmitters, neuromodulators and intrinsic conductances act together to regulate the activity of these important cells. PMID:21518033

  20. Control of abdominal and expiratory intercostal muscle activity during vomiting - Role of ventral respiratory group expiratory neurons

    NASA Technical Reports Server (NTRS)

    Miller, Alan D.; Tan, L. K.; Suzuki, Ichiro

    1987-01-01

    The role of ventral respiratory group (VRG) expiratory (E) neurons in the control of abdominal and internal intercostal muscle activity during vomiting was investigated in cats. Two series of experiments were performed: in one, the activity of VRG E neurons was recorded during fictive vomiting in cats that were decerebrated, paralyzed, and artificially ventilated; in the second, the abdominal muscle activity during vomiting was compared before and after sectioning the axons of descending VRG E neurons in decerebrate spontaneously breathing cats. The results show that about two-thirds of VRG E neurons that project at least as far caudally as the lower thoracic cord contribute to internal intercostal muscle activity during vomiting. The remaining VRG E neurons contribute to abdominal muscle activation. As shown by severing the axons of the VRG E neurons, other, as yet unidenified, inputs (either descending from the brain stem or arising from spinal reflexes) can also produce abdominal muscle activation.

  1. Regulation of cerebral blood flow in the hippocampus by neuronal activation through the perforant path: relationship between hippocampal blood flow and neuronal plasticity.

    PubMed

    Hamadate, Naobumi; Yamaguchi, Taku; Sugawara, Aya; Tsujimatsu, Aki; Izumi, Takeshi; Yoshida, Takayuki; Ohmura, Yu; Yoshioka, Mitsuhiro

    2