Sample records for a2 noradrenergic neurons

  1. Cholinergic neurons of mouse intrinsic cardiac ganglia contain noradrenergic enzymes, norepinephrine transporters, and the neurotrophin receptors TrkA and p75

    PubMed Central

    Hoard, Jennifer L.; Hoover, Donald B.; Mabe, Abigail M.; Blakely, Randy D.; Feng, Ning; Paolocci, Nazareno

    2008-01-01

    Half of the cholinergic neurons of human and primate intrinsic cardiac ganglia (ICG) have a dual cholinergic/noradrenergic phenotype. Likewise, a large subpopulation of cholinergic neurons of the mouse heart express enzymes needed for synthesis of norepinephrine (NE), but they lack the vesicular monoamine transporter type 2 (VMAT2) required for catecholamine storage. In the present study, we determined the full scope of noradrenergic properties (i.e., synthetic enzymes and transporters) expressed by cholinergic neurons of mouse ICG, estimated the relative abundance of neurons expressing different elements of the noradrenergic phenotype, and evaluated the colocalization of cholinergic and noradrenergic markers in atrial nerve fibers. Stellate ganglia were used as a positive control for noradrenergic markers. Using fluorescence immunohistochemistry and confocal microscopy, we found that about 30% of cholinergic cell bodies contained tyrosine hydroxylase (TH), including the activated form that is phosphorylated at Ser-40 (pSer40 TH). Dopamine β-hydroxylase (DBH) and NE transporter (NET) were present in all cholinergic somata, indicating a wider capability for dopamine metabolism and catecholamine uptake. Yet, cholinergic somata lacked VMAT2, precluding the potential for NE storage and vesicular release. In contrast to cholinergic somata, cardiac nerve fibers rarely showed colocalization of cholinergic and noradrenergic markers. Instead, these labels were closely apposed but clearly distinct from each other. Since cholinergic somata expressed several noradrenergic proteins, we questioned whether these neurons might also contain trophic factor receptors typical of noradrenergic neurons. Indeed, we found that all cholinergic cell bodies of mouse ICG, like noradrenergic cell bodies of the stellate ganglia, contained both tropomyosin-related kinase A (TrkA) and p75 neurotrophin receptors. Collectively, these findings demonstrate that mouse intrinsic cardiac neurons (ICNs

  2. Cholinergic neurons of mouse intrinsic cardiac ganglia contain noradrenergic enzymes, norepinephrine transporters, and the neurotrophin receptors tropomyosin-related kinase A and p75.

    PubMed

    Hoard, J L; Hoover, D B; Mabe, A M; Blakely, R D; Feng, N; Paolocci, N

    2008-09-22

    Half of the cholinergic neurons of human and primate intrinsic cardiac ganglia (ICG) have a dual cholinergic/noradrenergic phenotype. Likewise, a large subpopulation of cholinergic neurons of the mouse heart expresses enzymes needed for synthesis of norepinephrine (NE), but they lack the vesicular monoamine transporter type 2 (VMAT2) required for catecholamine storage. In the present study, we determined the full scope of noradrenergic properties (i.e. synthetic enzymes and transporters) expressed by cholinergic neurons of mouse ICG, estimated the relative abundance of neurons expressing different elements of the noradrenergic phenotype, and evaluated the colocalization of cholinergic and noradrenergic markers in atrial nerve fibers. Stellate ganglia were used as a positive control for noradrenergic markers. Using fluorescence immunohistochemistry and confocal microscopy, we found that about 30% of cholinergic cell bodies contained tyrosine hydroxylase (TH), including the activated form that is phosphorylated at Ser-40 (pSer40 TH). Dopamine beta-hydroxylase (DBH) and norepinephrine transporter (NET) were present in all cholinergic somata, indicating a wider capability for dopamine metabolism and catecholamine uptake. Yet, cholinergic somata lacked VMAT2, precluding the potential for NE storage and vesicular release. In contrast to cholinergic somata, cardiac nerve fibers rarely showed colocalization of cholinergic and noradrenergic markers. Instead, these labels were closely apposed but clearly distinct from each other. Since cholinergic somata expressed several noradrenergic proteins, we questioned whether these neurons might also contain trophic factor receptors typical of noradrenergic neurons. Indeed, we found that all cholinergic cell bodies of mouse ICG, like noradrenergic cell bodies of the stellate ganglia, contained both tropomyosin-related kinase A (TrkA) and p75 neurotrophin receptors. Collectively, these findings demonstrate that mouse intrinsic cardiac

  3. Chlorotoxin-mediated disinhibition of noradrenergic locus coeruleus neurons using a conditional transgenic approach.

    PubMed

    Salbaum, J Michael; Cirelli, Chiara; Walcott, Elisabeth; Krushel, Les A; Edelman, Gerald M; Tononi, Giulio

    2004-07-30

    The noradrenergic locus coeruleus (LC) has been implicated in the promotion of arousal, in focused attention and learning, and in the regulation of the sleep/waking cycle. The complex biological functions of the central noradrenergic system have been investigated largely through electrophysiological recordings and neurotoxic lesions of LC neurons. Activation of LC neurons through electrical or chemical stimulation has also led to important insights, although these techniques have limited cellular specificity and short-term effects. Here, we describe a novel method aimed at stimulating the central noradrenergic system in a highly selective manner for prolonged periods of time. This was achieved through the conditional expression of a transgene for chlorotoxin (Cltx) in the LC of adult mice. Chlorotoxin is a component of scorpion venom that partially blocks small conductance chloride channels. In this manner, the influence of GABAergic and glycinergic inhibitory inputs on LC cells is greatly reduced, while their ability to respond to excitatory inputs is unaffected. We demonstrate that the unilateral induction of Cltx expression in the LC is associated with a concomitant ipsilateral increase in the expression of markers of noradrenergic activity in LC neurons. Moreover, LC disinhibition is associated with the ipsilateral induction of the immediate early gene NGFI-A in cortical and subcortical target areas. Unlike previous gain of function approaches, transgenic disinhibition of LC cells is highly selective and persists for at least several weeks. This method represents a powerful new tool to assess the long-term effects of LC activation and is potentially applicable to other neuronal systems.

  4. Cholecystokinin-8 induces brain-derived neurotrophic factor expression in noradrenergic neuronal cells.

    PubMed

    Hwang, Cheol Kyu; Kim, Do Kyung; Chun, Hong Sung

    2013-08-01

    The sulfated cholecystokinin octapeptide (CCK-8S) is one of the most abundant CCK fragment in the brain, but the effects of CCK-8S on locus coeruleus (LC) noradrenergic (NA) neuronal cells activity have not been studied. In this study, we investigated the effects of CCK-8S on the expression of brain-derived neurotrophic factor (BDNF) in LC NA neuronal cell line, LC3541. Results showed that CCK-8S (10 nM) elevates BDNF levels time-dependently and by 1.82-fold after 4h of incubation. In addition, pretreatment with CCK-8S reversed H₂O₂ (100 μM)-mediated down-regulation of BDNF expression, and effectively suppressed H₂O₂-induced caspase-3 activation. Furthermore, CCK-8S markedly induced expression of neuronal survival markers, such as extracellular signal-regulated kinase 1/2 (ERK 1/2), Akt/protein kinase B (PKB), Bcl-2, and peroxisome proliferators-activated receptor gamma coactivator-1α (PGC-1α). Pharmacological inhibitors of ERK 1/2, Akt/PKB, and protein kinase A (PKA) reversed CCK-8S-mediated BDNF induction in LC3541 cells. These results suggest the first evidence that CCK-8S can protect noradrenergic neurons and enhance the expression of BDNF via ERK 1/2-Akt/PKB-PKA-dependent pathways. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. Transcription factor activating protein 2 beta (TFAP2B) mediates noradrenergic neuronal differentiation in neuroblastoma.

    PubMed

    Ikram, Fakhera; Ackermann, Sandra; Kahlert, Yvonne; Volland, Ruth; Roels, Frederik; Engesser, Anne; Hertwig, Falk; Kocak, Hayriye; Hero, Barbara; Dreidax, Daniel; Henrich, Kai-Oliver; Berthold, Frank; Nürnberg, Peter; Westermann, Frank; Fischer, Matthias

    2016-02-01

    Neuroblastoma is an embryonal pediatric tumor that originates from the developing sympathetic nervous system and shows a broad range of clinical behavior, ranging from fatal progression to differentiation into benign ganglioneuroma. In experimental neuroblastoma systems, retinoic acid (RA) effectively induces neuronal differentiation, and RA treatment has been therefore integrated in current therapies. However, the molecular mechanisms underlying differentiation are still poorly understood. We here investigated the role of transcription factor activating protein 2 beta (TFAP2B), a key factor in sympathetic nervous system development, in neuroblastoma pathogenesis and differentiation. Microarray analyses of primary neuroblastomas (n = 649) demonstrated that low TFAP2B expression was significantly associated with unfavorable prognostic markers as well as adverse patient outcome. We also found that low TFAP2B expression was strongly associated with CpG methylation of the TFAP2B locus in primary neuroblastomas (n = 105) and demethylation with 5-aza-2'-deoxycytidine resulted in induction of TFAP2B expression in vitro, suggesting that TFAP2B is silenced by genomic methylation. Tetracycline inducible re-expression of TFAP2B in IMR-32 and SH-EP neuroblastoma cells significantly impaired proliferation and cell cycle progression. In IMR-32 cells, TFAP2B induced neuronal differentiation, which was accompanied by up-regulation of the catecholamine biosynthesizing enzyme genes DBH and TH, and down-regulation of MYCN and REST, a master repressor of neuronal genes. By contrast, knockdown of TFAP2B by lentiviral transduction of shRNAs abrogated RA-induced neuronal differentiation of SH-SY5Y and SK-N-BE(2)c neuroblastoma cells almost completely. Taken together, our results suggest that TFAP2B is playing a vital role in retaining RA responsiveness and mediating noradrenergic neuronal differentiation in neuroblastoma. Copyright © 2015 Federation of European Biochemical Societies

  6. A noradrenergic lesion exacerbates neurodegeneration in a Down syndrome mouse model.

    PubMed

    Lockrow, Jason; Boger, Heather; Gerhardt, Greg; Aston-Jones, Gary; Bachman, David; Granholm, Ann-Charlotte

    2011-01-01

    Individuals with Down syndrome (DS) acquire Alzheimer's-like dementia (AD) and associated neuropathology earlier and at significantly greater rates than age-matched normosomic individuals. However, biological mechanisms have not been discovered and there is currently limited therapy for either DS- or AD-related dementia. Segmental trisomy 16 (Ts65Dn) mice provide a useful model for many of the degenerative changes which occur with age in DS including cognitive deficits, neuroinflammation, and degeneration of basal forebrain cholinergic neurons. Loss of noradrenergic locus coeruleus (LC) neurons is an early event in AD and in DS, and may contribute to the neuropathology. We report that Ts65Dn mice exhibit progressive loss of norepinephrine (NE) phenotype in LC neurons. In order to determine whether LC degeneration contributes to memory loss and neurodegeneration in Ts65Dn mice, we administered the noradrenergic neurotoxin N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4; 2 doses of 50 mg/kg, i.p.) to Ts65Dn mice at four months of age, prior to working memory loss. At eight months of age, Ts65Dn mice treated with DSP-4 exhibited an 80% reduction in hippocampal NE, coupled with a marked increase in hippocampal neuroinflammation. Noradrenergic depletion also resulted in accelerated cholinergic neuron degeneration and a further impairment of memory function in Ts65Dn mice. In contrast, DSP-4 had minimal effects on normosomic littermates, suggesting a disease-modulated vulnerability to NE loss in the DS mouse model. These data suggest that noradrenergic degeneration may play a role in the progressive memory loss, neuroinflammation, and cholinergic loss occurring in DS individuals, providing a possible therapeutic avenue for future clinical studies.

  7. A Noradrenergic Lesion Exacerbates Neurodegeneration in a Down Syndrome Mouse Model

    PubMed Central

    Lockrow, Jason; Boger, Heather; Gerhardt, Greg; Aston-Jones, Gary; Bachman, David; Granholm, Ann-Charlotte

    2012-01-01

    Individuals with Down syndrome (DS) acquire Alzheimer’s-like dementia (AD) and associated neuropathology earlier and at significantly greater rates than age-matched normosomic individuals. However, biological mechanisms have not been discovered and there is currently limited therapy for either DS- or AD-related dementia. Segmental trisomy 16 (Ts65Dn) mice provide a useful model for many of the degenerative changes which occur with age in DS including cognitive deficits, neuroinflammation, and degeneration of basal forebrain cholinergic neurons. Loss of noradrenergic locus coeruleus (LC) neurons is an early event in AD and in DS, and may contribute to the neuropathology. We report that Ts65Dn mice exhibit progressive loss of norepinephrine (NE) phenotype in LC neurons. In order to determine whether LC degeneration contributes to memory loss and neurodegeneration in Ts65Dn mice, we administered the noradrenergic neurotoxin N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4; 2 doses of 50 mg/kg, i.p.) to Ts65Dn mice at four months of age, prior to working memory loss. At eight months of age, Ts65Dn mice treated with DSP-4 exhibited an 80% reduction in hippocampal NE, coupled with a marked increase in hippocampal neuroinflammation. Noradrenergic depletion also resulted in accelerated cholinergic neuron degeneration and a further impairment of memory function in Ts65Dn mice. In contrast, DSP-4 had minimal effects on normosomic littermates, suggesting a disease-modulated vulnerability to NE loss in the DS mouse model. These data suggest that noradrenergic degeneration may play a role in the progressive memory loss, neuroinflammation, and cholinergic loss occurring in DS individuals, providing a possible therapeutic avenue for future clinical studies. PMID:21098982

  8. Role of nucleus of the solitary tract noradrenergic neurons in post-stress cardiovascular and hormonal control in male rats

    PubMed Central

    Bundzikova-Osacka, Jana; Ghosal, Sriparna; Packard, Benjamin A.; Ulrich-Lai, Yvonne M.; Herman, James P.

    2015-01-01

    Chronic stress causes hypothalamo-pituitary-adrenal (HPA) axis hyperactivity and cardiovascular dyshomeostasis. Noradrenergic neurons in the nucleus of the solitary tract (NTS) are considered to play a role in these changes. Here, we tested the hypothesis that NTS noradrenergic A2 neurons are required for cardiovascular and HPA axis responses to both acute and chronic stress. Adult male rats received bilateral microinjection into the NTS of 6-hydroxydopamine (6-OHDA) to lesion A2 neurons [cardiovascular study, n= 5; HPA study, n= 5], or vehicle [cardiovascular study, n= 6; HPA study, n= 4]. Rats were exposed to acute restraint stress followed by 14 days of chronic variable stress (CVS). On the last day of testing, rats were placed in a novel elevated plus maze (EPM) to test post-CVS stress responses. Lesions of NTS A2 neurons reduced the tachycardic response to acute restraint, confirming that A2 neurons promote sympathetic activation following acute stress. In addition, CVS increased the ratio of low frequency to high frequency power for heart rate variability, indicative of sympathovagal imbalance, and this effect was significantly attenuated by 6-OHDA lesion. Lesions of NTS A2 neurons reduced acute restraint-induced corticosterone secretion, but did not affect the corticosterone response to the EPM, indicating that A2 neurons promote acute HPA axis responses, but are not involved in CVS-mediated HPA axis sensitization. Collectively, these data indicate that A2 neurons promote both cardiovascular and HPA axis responses to acute stress. Moreover, A2 catecholaminergic neurons may contribute to the potentially deleterious enhancement of sympathetic drive following chronic stress. PMID:25765732

  9. Sex differences in the expression of estrogen receptor alpha within noradrenergic neurons in the sheep brain stem.

    PubMed

    Rose, J L; Hamlin, A S; Scott, C J

    2014-10-01

    In female sheep, high levels of estrogen exert a positive feedback action on gonadotropin releasing hormone (GnRH) secretion to stimulate a surge in luteinizing hormone (LH) secretion. Part of this action appears to be via brain stem noradrenergic neurons. By contrast, estrogen action in male sheep has a negative feedback action to inhibit GnRH and LH secretion. To investigate whether part of this sex difference is due to differences in estrogen action in the brain stem, we tested the hypothesis that the distribution of estrogen receptor α (ERα) within noradrenergic neurons in the brain stem differs between rams and ewes. To determine the distribution of ERα, we used double-label fluorescence immunohistochemistry for dopamine β-Hydroxylase, as a marker for noradrenergic and adrenergic cells, and ERα. In the ventrolateral medulla (A1 region), most ERα-immunoreactive (-ir) cells were located in the caudal part of the nucleus. Overall, there were more ERα-ir cells in rams than ewes, but the proportion of double-labeled cells was did not differ between sexes. Much greater numbers of ERα-ir cells were found in the nucleus of the solitary tract (A2 region), but <10% were double labeled and there were no sex differences. The majority of ERα-labeled cells in this nucleus was located in the more rostral areas. ERα-labeled cells were found in several rostral brain stem regions but none of these were double labeled and so were not quantified. Because there was no sex difference in the number of ERα-ir cells in the brain stem that were noradrenergic, the sex difference in the action of estrogen on gonadotropin secretion in sheep is unlikely to involve actions on brain stem noradrenergic cells. Crown Copyright © 2014. Published by Elsevier Inc. All rights reserved.

  10. Augmentation of the noradrenergic system in alpha-2 adrenergic receptor deficient mice: anatomical changes associated with enhanced fear memory.

    PubMed

    Davies, M Frances; Tsui, Janet Y; Flannery, Judy A; Li, Xiangqi; DeLorey, Timothy M; Hoffman, Brian B

    2003-10-03

    We have investigated sensitivity to the conditioned fear procedure of mice is influenced by the genetic deletion of alpha2A adrenoceptors (ARs). We observed a heightened freezing response in the discrete cue memory test in alpha2A AR knockout (alpha2A AR KO) mice and in D79N mice, a transgenic mouse strain with functionally impaired alpha2A ARs. No significant differences in contextual memory were observed between control and alpha2A AR KO or D79N mice suggesting a minimal role for the noradrenergic system in contextual memory. We speculated that the increased freezing response of the alpha2A AR KO and D79N mice in the discrete cue setting was due to increased release of norepinephrine evoked by the unconditioned footshock stimulus. In alpha2A AR KO mice we measured a doubling in the number of noradrenergic neurons in the locus coeruleus (LC) and a large increase in the cell volume of tyrosine hydroxylase positive neurons, likely due to selective preservation of large, multipolar neurons in the subcoeruleus. Hyperplasia of the noradrenergic neurons in the nucleus tractus solitarius, A5 and A7, was also observed. Alpha2A AR KO mice exhibit greater c-Fos expression in the LC compared to wild type mice suggesting that the LC neurons in the alpha2A AR KO mice were spontaneously more active. This study suggests that alpha2A ARs are involved in the development of the central noradrenergic system and raises the possibility that alterations in alpha2A AR expression may contribute to variations in fear and stress responses.

  11. Vascular Mural Cells Promote Noradrenergic Differentiation of Embryonic Sympathetic Neurons.

    PubMed

    Fortuna, Vitor; Pardanaud, Luc; Brunet, Isabelle; Ola, Roxana; Ristori, Emma; Santoro, Massimo M; Nicoli, Stefania; Eichmann, Anne

    2015-06-23

    The sympathetic nervous system controls smooth muscle tone and heart rate in the cardiovascular system. Postganglionic sympathetic neurons (SNs) develop in close proximity to the dorsal aorta (DA) and innervate visceral smooth muscle targets. Here, we use the zebrafish embryo to ask whether the DA is required for SN development. We show that noradrenergic (NA) differentiation of SN precursors temporally coincides with vascular mural cell (VMC) recruitment to the DA and vascular maturation. Blocking vascular maturation inhibits VMC recruitment and blocks NA differentiation of SN precursors. Inhibition of platelet-derived growth factor receptor (PDGFR) signaling prevents VMC differentiation and also blocks NA differentiation of SN precursors. NA differentiation is normal in cloche mutants that are devoid of endothelial cells but have VMCs. Thus, PDGFR-mediated mural cell recruitment mediates neurovascular interactions between the aorta and sympathetic precursors and promotes their noradrenergic differentiation. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  12. Disinhibition of perifornical hypothalamic neurones activates noradrenergic neurones and blocks pontine carbachol-induced REM sleep-like episodes in rats

    PubMed Central

    Lu, Jackie W; Fenik, Victor B; Branconi, Jennifer L; Mann, Graziella L; Rukhadze, Irma; Kubin, Leszek

    2007-01-01

    Studies in behaving animals suggest that neurones located in the perifornical (PF) region of the posterior hypothalamus promote wakefulness and suppress sleep. Among such cells are those that synthesize the excitatory peptides, orexins (ORX). Lack of ORX, or their receptors, is associated with narcolepsy/cataplexy, a disorder characterized by an increased pressure for rapid eye movement (REM) sleep. We used anaesthetized rats in which pontine microinjections of a cholinergic agonist, carbachol, can repeatedly elicit REM sleep-like episodes to test whether activation of PF cells induced by antagonism of endogenous, GABAA receptor-mediated, inhibition suppresses the ability of the brainstem to generate REM sleep-like state. Microinjections of the GABAA receptor antagonist, bicuculline (20 nl, 1 mm), into the PF region elicited cortical and hippocampal activation, increased the respiratory rate and hypoglossal nerve activity, induced c-fos expression in ORX and other PF neurones, and increased c-fos expression in pontine A7 and other noradrenergic neurones. The ability of pontine carbachol to elicit any cortical, hippocampal or brainstem component of the REM sleep-like response was abolished during the period of bicuculline-induced activation. The activating and REM sleep-suppressing effect of PF bicuculline was not attenuated by systemic administration of the ORX type 1 receptor antagonist, SB334867. Thus, activation of PF neurones that are endogenously inhibited by GABAA receptors is sufficient to turn off the brainstem REM sleep-generating network; the effect is, at least in part, due to activation of pontine noradrenergic neurones, but is not mediated by ORX type 1 receptors. A malfunction of the pathway that originates in GABAA receptor-expressing PF neurones may cause narcolepsy/cataplexy. PMID:17495048

  13. On the Origin of Cortical Dopamine: Is it a Co-Transmitter in Noradrenergic Neurons?

    PubMed Central

    Devoto, Paola; Flore, Giovanna

    2006-01-01

    Dopamine (DA) and noradrenaline (NA) in the prefrontal cortex (PFC) modulate superior cognitive functions, and are involved in the aetiology of depressive and psychotic symptoms. Moreover, microdialysis studies in rats have shown how pharmacological treatments that induce modifications of extracellular NA in the medial PFC (mPFC), also produce parallel changes in extracellular DA. To explain the coupling of NA and DA changes, this article reviews the evidence supporting the hypothesis that extracellular DA in the cerebral cortex originates not only from dopaminergic terminals but also from noradrenergic ones, where it acts both as precursor for NA and as a co-transmitter. Accordingly, extracellular DA concentration in the occipital, parietal and cerebellar cortex was found to be much higher than expected in view of the scarce dopaminergic innervation in these areas. Systemic administration or intra-cortical perfusion of α2-adrenoceptor agonists and antagonists, consistent with their action on noradrenergic neuronal activity, produced concomitant changes not only in extracellular NA but also in DA in the mPFC, occipital and parietal cortex. Chemical modulation of the locus coeruleus by locally applied carbachol, kainate, NMDA or clonidine modified both NA and DA in the mPFC. Electrical stimulation of the locus coeruleus led to an increased efflux of both NA and DA in mPFC, parietal and occipital cortex, while in the striatum, NA efflux alone was enhanced. Atypical antipsychotics, such as clozapine and olanzapine, or antidepressants, including mirtazapine and mianserine, have been found to increase both NA and DA throughout the cerebral cortex, likely through blockade of α2-adrenoceptors. On the other hand, drugs selectively acting on dopaminergic transmission produced modest changes in extracellular DA in mPFC, and had no effect on the occipital or parietal cortex. Acute administration of morphine did not increase DA levels in the PFC (where NA is diminished), in

  14. On the origin of cortical dopamine: is it a co-transmitter in noradrenergic neurons?

    PubMed

    Devoto, Paola; Flore, Giovanna

    2006-04-01

    Dopamine (DA) and noradrenaline (NA) in the prefrontal cortex (PFC) modulate superior cognitive functions, and are involved in the aetiology of depressive and psychotic symptoms. Moreover, microdialysis studies in rats have shown how pharmacological treatments that induce modifications of extracellular NA in the medial PFC (mPFC), also produce parallel changes in extracellular DA.To explain the coupling of NA and DA changes, this article reviews the evidence supporting the hypothesis that extracellular DA in the cerebral cortex originates not only from dopaminergic terminals but also from noradrenergic ones, where it acts both as precursor for NA and as a co-transmitter.Accordingly, extracellular DA concentration in the occipital, parietal and cerebellar cortex was found to be much higher than expected in view of the scarce dopaminergic innervation in these areas.Systemic administration or intra-cortical perfusion of alpha(2)-adrenoceptor agonists and antagonists, consistent with their action on noradrenergic neuronal activity, produced concomitant changes not only in extracellular NA but also in DA in the mPFC, occipital and parietal cortex.Chemical modulation of the locus coeruleus by locally applied carbachol, kainate, NMDA or clonidine modified both NA and DA in the mPFC.Electrical stimulation of the locus coeruleus led to an increased efflux of both NA and DA in mPFC, parietal and occipital cortex, while in the striatum, NA efflux alone was enhanced.Atypical antipsychotics, such as clozapine and olanzapine, or antidepressants, including mirtazapine and mianserine, have been found to increase both NA and DA throughout the cerebral cortex, likely through blockade of alpha(2)-adrenoceptors. On the other hand, drugs selectively acting on dopaminergic transmission produced modest changes in extracellular DA in mPFC, and had no effect on the occipital or parietal cortex.Acute administration of morphine did not increase DA levels in the PFC (where NA is diminished

  15. Selective deficiencies in descending inhibitory modulation in neuropathic rats: implications for enhancing noradrenergic tone.

    PubMed

    Patel, Ryan; Qu, Chaoling; Xie, Jennifer Y; Porreca, Frank; Dickenson, Anthony H

    2018-06-22

    Pontine noradrenergic neurones form part of a descending inhibitory system that influences spinal nociceptive processing. Weak or absent descending inhibition is a common feature of chronic pain patients. We examined the extent to which the descending noradrenergic system is tonically active, how control of spinal neuronal excitability is integrated into thalamic relays within sensory-discriminative projection pathways, and how this inhibitory control is altered after nerve injury. In vivo electrophysiology was performed in anaesthetised spinal nerve-ligated (SNL) and sham-operated rats to record from wide dynamic range neurones in the ventral posterolateral thalamus (VPL). In sham rats, spinal block of α2-adrenoceptors with atipamezole resulted in enhanced stimulus-evoked and spontaneous firing in the VPL, and produced conditioned place avoidance. However, in SNL rats, these conditioned avoidance behaviours were absent. Furthermore, inhibitory control of evoked neuronal responses was lost, but spinal atipamezole markedly increased spontaneous firing. Augmenting spinal noradrenergic tone in neuropathic rats with reboxetine, a selective noradrenergic reuptake inhibitor, modestly reinstated inhibitory control of evoked responses in the VPL but had no effect on spontaneous firing. By contrast, clonidine, an α2 agonist, inhibited both evoked and spontaneous firing, and exhibited increased potency in SNL rats compared with sham controls. These data suggest descending noradrenergic inhibitory pathways are tonically active in sham rats. Moreover, in neuropathic states, descending inhibitory control is diminished, but not completely absent, and distinguishes between spontaneous and evoked neuronal activity. These observations may have implications for how analgesics targeting the noradrenergic system provide relief.This is an open access article distributed under the Creative Commons Attribution License 4.0 (CCBY), which permits unrestricted use, distribution, and

  16. In vitro characterization of noradrenergic modulation of chemosensitive neurons in the retrotrapezoid nucleus

    PubMed Central

    Kuo, Fu-Shan; Falquetto, Bárbara; Chen, Dawei; Oliveira, Luiz M.; Takakura, Ana C.

    2016-01-01

    Chemosensitive neurons in the retrotrapezoid nucleus (RTN) regulate breathing in response to CO2/H+ changes and serve as an integration center for other autonomic centers, including brain stem noradrenergic neurons. Norepinephrine (NE) contributes to respiratory control and chemoreception, and, since disruption of NE signaling may contribute to several breathing disorders, we sought to characterize effects of NE on RTN chemoreception. All neurons included in this study responded similarly to CO2/H+ but showed differential sensitivity to NE; we found that NE activated (79%), inhibited (7%), or had no effect on activity (14%) of RTN chemoreceptors. The excitatory effect of NE on RTN chemoreceptors was dose dependent, retained in the presence of neurotransmitter receptor blockers, and could be mimicked and blocked by pharmacological manipulation of α1-adrenergic receptors (ARs). In addition, NE-activation was blunted by XE991 (KCNQ channel blocker), and partially occluded the firing response to serotonin, suggesting involvement of KCNQ channels. However, in whole cell voltage clamp, activation of α1-ARs decreased outward current and conductance by what appears to be a mixed effect on multiple channels. The inhibitory effect of NE on RTN chemoreceptors was blunted by an α2-AR antagonist. A third group of RTN chemoreceptors was insensitive to NE. We also found that chemosensitive RTN astrocytes do not respond to NE with a change in voltage or by releasing ATP to enhance activity of chemosensitive neurons. These results indicate NE modulates subsets of RTN chemoreceptors by mechanisms involving α1- and α2-ARs. PMID:27306669

  17. Opioid and noradrenergic contributions of tapentadol to the inhibition of locus coeruleus neurons in the streptozotocin rat model of polyneuropathic pain.

    PubMed

    Torres-Sanchez, Sonia; Borges, Gisela Da Silva; Mico, Juan A; Berrocoso, Esther

    2018-06-01

    Tapentadol is an analgesic that acts as an agonist of µ opioid receptors (MOR) and that inhibits noradrenaline reuptake. Data from healthy rats show that tapentadol inhibits neuronal activity in the locus coeruleus (LC), a nucleus regulated by both the noradrenergic and opioid systems. Thus, we set out to investigate the effect of tapentadol on LC activity in streptozotocin (STZ)-induced diabetic rats, a model of diabetic polyneuropathy, by analyzing single-unit extracellular recordings of LC neurons. Four weeks after inducing diabetes, tapentadol dose-response curves were obtained from animals pre-treated with RX821002 or naloxone (alpha2-adrenoceptors and opioid receptors antagonists, respectively). In STZ rats, the spontaneous activity of LC neurons (0.9 ± 0.1 Hz) was lower than in naïve animals (1.5 ± 0.1 Hz), and tapentadol's inhibitory effect was also weaker. Alpha2-adrenoceptors blockade by RX821002 (100 μg/kg i.v.) in STZ animals significantly increased the spontaneous activity (from 0.8 ± 0.1 to 1.4 ± 0.2 Hz) and it dampened the inhibition of LC neurons produced by tapentadol. However, opioid receptors blockade following naloxone pre-treatment (5 mg/kg i.v.) did not alter the spontaneous firing rate (0.9 ± 0.2 vs 0.9 ± 0.2 Hz) or the inhibitory effect of tapentadol on LC neurons in STZ animals. Thus, diabetic polyneuropathy appears to exert neuroplastic changes in LC neurotransmission, enhancing the sensitivity of alpha2-adrenoceptors and dampening opioid receptors expression. Tapentadol's activity seems to be predominantly mediated through its noradrenergic effects rather than its influence on opioid receptors in the STZ model of diabetic polyneuropathy. Copyright © 2018 Elsevier Ltd. All rights reserved.

  18. Functional neuroanatomy of the central noradrenergic system.

    PubMed

    Szabadi, Elemer

    2013-08-01

    The central noradrenergic neurone, like the peripheral sympathetic neurone, is characterized by a diffusely arborizing terminal axonal network. The central neurones aggregate in distinct brainstem nuclei, of which the locus coeruleus (LC) is the most prominent. LC neurones project widely to most areas of the neuraxis, where they mediate dual effects: neuronal excitation by α₁-adrenoceptors and inhibition by α₂-adrenoceptors. The LC plays an important role in physiological regulatory networks. In the sleep/arousal network the LC promotes wakefulness, via excitatory projections to the cerebral cortex and other wakefulness-promoting nuclei, and inhibitory projections to sleep-promoting nuclei. The LC, together with other pontine noradrenergic nuclei, modulates autonomic functions by excitatory projections to preganglionic sympathetic, and inhibitory projections to preganglionic parasympathetic neurones. The LC also modulates the acute effects of light on physiological functions ('photomodulation'): stimulation of arousal and sympathetic activity by light via the LC opposes the inhibitory effects of light mediated by the ventrolateral preoptic nucleus on arousal and by the paraventricular nucleus on sympathetic activity. Photostimulation of arousal by light via the LC may enable diurnal animals to function during daytime. LC neurones degenerate early and progressively in Parkinson's disease and Alzheimer's disease, leading to cognitive impairment, depression and sleep disturbance.

  19. Role of nucleus of the solitary tract noradrenergic neurons in post-stress cardiovascular and hormonal control in male rats.

    PubMed

    Bundzikova-Osacka, Jana; Ghosal, Sriparna; Packard, Benjamin A; Ulrich-Lai, Yvonne M; Herman, James P

    2015-01-01

    Chronic stress causes hypothalamo-pituitary-adrenal (HPA) axis hyperactivity and cardiovascular dyshomeostasis. Noradrenergic (NA) neurons in the nucleus of the solitary tract (NTS) are considered to play a role in these changes. In this study, we tested the hypothesis that NTS NA A2 neurons are required for cardiovascular and HPA axis responses to both acute and chronic stress. Adult male rats received bilateral microinjection into the NTS of 6-hydroxydopamine (6-OHDA) to lesion A2 neurons [cardiovascular study, n = 5; HPA study, n = 5] or vehicle [cardiovascular study, n = 6; HPA study, n = 4]. Rats were exposed to acute restraint stress followed by 14 d of chronic variable stress (CVS). On the last day of testing, rats were placed in a novel elevated plus maze (EPM) to test post-CVS stress responses. Lesions of NTS A2 neurons reduced the tachycardic response to acute restraint, confirming that A2 neurons promote sympathetic activation following acute stress. In addition, CVS increased the ratio of low-frequency to high-frequency power for heart rate variability, indicative of sympathovagal imbalance, and this effect was significantly attenuated by 6-OHDA lesion. Lesions of NTS A2 neurons reduced acute restraint-induced corticosterone secretion, but did not affect the corticosterone response to the EPM, indicating that A2 neurons promote acute HPA axis responses, but are not involved in CVS-mediated HPA axis sensitization. Collectively, these data indicate that A2 neurons promote both cardiovascular and HPA axis responses to acute stress. Moreover, A2 catecholaminergic neurons may contribute to the potentially deleterious enhancement of sympathetic drive following chronic stress.

  20. Chronic restraint stress triggers dopaminergic and noradrenergic neurodegeneration: Possible role of chronic stress in the onset of Parkinson's disease.

    PubMed

    Sugama, Shuei; Sekiyama, Kazunari; Kodama, Tohru; Takamatsu, Yoshiki; Takenouchi, Takato; Hashimoto, Makoto; Bruno, Conti; Kakinuma, Yoshihiko

    2016-01-01

    Parkinson's disease (PD) is a neurodegenerative disease characterized by the loss of dopaminergic (DA) neurons in the substantia nigra pars compacta (SNpc) and, to a lesser extent, in the noradrenergic neurons of the locus coeruleus (LC). Most cases of PD are idiopathic and sporadic and are believed to be the result of both environmental and genetic factors. Here, to the best of our knowledge, we report the first evidence that chronic restraint stress (8h/day, 5days/week) substantially reduces nigral DA and LC noradrenergic neuronal cell numbers in rats. Loss of DA neurons in the SNpc was evident after 2weeks of stress and progressed in a time-dependent manner, reaching up to 61% at 16weeks. This reduction was accompanied by robust microglial activation and oxidative stress and was marked by nitrotyrosine in the SNpc and LC of the midbrain. These results indicate that chronic stress triggers DA and noradrenergic neurodegeneration by increasing oxidative stress, and that activated microglia in the substantia nigra and LC may play an important role in modulating the neurotoxic effects of oxidative stress. Taken together, these data suggest that exposure to chronic stress triggers DA and noradrenergic neurodegeneration, which is a cause of PD. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. Noradrenergic lesioning with an anti-dopamine beta-hydroxylase immunotoxin

    NASA Technical Reports Server (NTRS)

    Picklo, M. J.; Wiley, R. G.; Lappi, D. A.; Robertson, D.

    1994-01-01

    Sympathectomy has been achieved by a variety of methods but each has its limitations. These include lack of tissue specificity, incomplete lesioning, and the age range of susceptibility to the lesioning. To circumvent these drawbacks, an immunotoxin was constructed using a monoclonal antibody against the noradrenergic specific enzyme dopamine beta-hydroxylase (D beta H) coupled via a disulfide bond to saporin, a ribosomal inactivating protein. Three days after intravenous injection of the anti-D beta H immunotoxin (50 micrograms) into adult Sprague-Dawley rats, 66% of neurons in the superior cervical ganglia were chromatolytic. Superior cervical ganglia neurons were poisoned in 1 day old and 1 week old (86% of neurons) neonatal rats following subcutaneous injection of 3.75 and 15 micrograms, respectively. The anti-D beta H immunotoxin will be a useful tool in the study of the peripheral noradrenergic system in adult and neonatal animals.

  2. Quantitative RT-PCR and immunoblot analyses reveal acclimated A2 noradrenergic neuron substrate fuel transporter, glucokinase, phospho-AMPK, and dopamine-β-hydroxylase responses to hypoglycemia.

    PubMed

    Cherian, Ajeesh Koshy; Briski, Karen P

    2011-07-01

    Cellular metabolic stasis is monitored in discrete brain sites, including the dorsal vagal complex (DVC), where A2 noradrenergic neurons perform this sensory function. Single-cell qPCR and high-sensitivity immunoblotting were used to determine if A2 neurons adapt to chronic hypoglycemia by increasing substrate fuel transporter expression, and whether such adjustments coincide with decreased cellular energy instability during this systemic metabolic stress. Tyrosine hydroxylase-immunolabeled neurons were laser-microdissected from the caudal DVC 2 hr after single or serial neutral protamine Hagedorn insulin (NPH) dosing. Preceding hypoglycemia suppressed basal A2 MCT2, GLUT3, and GLUT4 profiles and diminished MCT2, GLUT4, and glucokinase responses to recurring hypoglycemia. Acute NPH caused a robust increase in A2 phospho-AMPK protein levels; baseline phospho-AMPK expression was elevated after 3 days of insulin treatment but only slight augmented after a fourth NPH injection. Transcripts encoding the catecholamine biosynthetic enzyme dopamine-β-hydroxylase were unaffected by acute NPH but were diminished by serial insulin dosing. This evidence for diminished basal A2 glucose and lactate uptake and attenuated phospho-AMPK-mediated detection of hypoglycemia-associated energy deficits suggests that these cells acclimate to chronic hypoglycemia by adopting a new metabolic steady state characterized by energy paucity and reduced sensitivity to hypoglycemia. Because dopamine-β-hydroxylase mRNA was reduced after serial, but not single NPH dosing, A2 neurotransmitter biosynthesis may be impervious to acute hypoglycemia but inhibited when posthypoglycemic metabolic deficiency is exacerbated by recurring hypoglycemia. This research suggests that chronic hypoglycemia-associated adjustments in A2-sensory neurotransmission may reflect cellular energetic debilitation rather than adaptive attenuation of cellular metabolic imbalance. Copyright © 2011 Wiley-Liss, Inc.

  3. Selective ablation of dorsal horn NK1 expressing cells reveals a modulation of spinal alpha2-adrenergic inhibition of dorsal horn neurones.

    PubMed

    Rahman, Wahida; Suzuki, Rie; Hunt, Stephen P; Dickenson, Anthony H

    2008-06-01

    Activity in descending systems from the brainstem modulates nociceptive transmission through the dorsal horn. Intrathecal injection of the neurotoxin saporin conjugated to SP (SP-SAP) into the lumbar spinal cord results in the selective ablation of NK(1) receptor expressing (NK(1)+ve) neurones in the superficial dorsal horn (lamina I/III). Loss of these NK(1)+ve neurones attenuates excitability of deep dorsal horn neurones due to a disruption of both intrinsic spinal circuits and a spino-bulbo-spinal loop, which activates a descending excitatory drive, mediated through spinal 5HT(3) receptors. Descending inhibitory pathways also modulate spinal activity and hence control the level of nociceptive transmission relayed to higher centres. To ascertain the spinal origins of the major descending noradrenergic inhibitory pathway we studied the effects of a selective alpha2-adrenoceptor antagonist, atipamezole, on neuronal activity in animals pre-treated with SP-SAP. Intrathecal application of atipamezole dose dependently facilitated the mechanically evoked neuronal responses of deep dorsal horn neurones to low intensity von Frey hairs (5-15 g) and noxious thermal (45-50 degrees C) evoked responses in SAP control animals indicating a physiological alpha2-adrenoceptor control. This facilitatory effect of atipamezole was lost in the SP-SAP treated group. These data suggest that activity within noradrenergic pathways have a dependence on dorsal horn NK(1)+ve cells. Further, noradrenergic descending inhibition may in part be driven by lamina I/III (NK(1)+ve) cells, and mediated via spinal alpha2-adrenoceptor activation. Since the same neuronal population drives descending facilitation and inhibition, the reduced excitability of lamina V/VI WDR neurones seen after loss of these NK(1)+ve neurones indicates a dominant role of descending facilitation.

  4. Orexin neurons suppress narcolepsy via 2 distinct efferent pathways

    PubMed Central

    Hasegawa, Emi; Yanagisawa, Masashi; Sakurai, Takeshi; Mieda, Michihiro

    2014-01-01

    The loss of orexin neurons in humans is associated with the sleep disorder narcolepsy, which is characterized by excessive daytime sleepiness and cataplexy. Mice lacking orexin peptides, orexin neurons, or orexin receptors recapitulate human narcolepsy phenotypes, further highlighting a critical role for orexin signaling in the maintenance of wakefulness. Despite the known role of orexin neurons in narcolepsy, the precise neural mechanisms downstream of these neurons remain unknown. We found that targeted restoration of orexin receptor expression in the dorsal raphe (DR) and in the locus coeruleus (LC) of mice lacking orexin receptors inhibited cataplexy-like episodes and pathological fragmentation of wakefulness (i.e., sleepiness), respectively. The suppression of cataplexy-like episodes correlated with the number of serotonergic neurons restored with orexin receptor expression in the DR, while the consolidation of fragmented wakefulness correlated with the number of noradrenergic neurons restored in the LC. Furthermore, pharmacogenetic activation of these neurons using designer receptor exclusively activated by designer drug (DREADD) technology ameliorated narcolepsy in mice lacking orexin neurons. These results suggest that DR serotonergic and LC noradrenergic neurons play differential roles in orexin neuron–dependent regulation of sleep/wakefulness and highlight a pharmacogenetic approach for the amelioration of narcolepsy. PMID:24382351

  5. The role of central noradrenergic dysregulation in anxiety disorders: evidence from clinical studies.

    PubMed

    Kalk, N J; Nutt, D J; Lingford-Hughes, A R

    2011-01-01

    The nature of the noradrenergic dysregulation in clinical anxiety disorders remains unclear. In panic disorder, the predominant view has been that central noradrenergic neuronal networks and/or the sympathetic nervous system was normal in patients at rest, but hyper-reactive to specific stimuli, for example carbon dioxide. These ideas have been extended to other anxiety disorders, which share with panic disorder characteristic subjective anxiety and physiological symptoms of excess sympathetic activity. For example, Generalized Anxiety Disorder is characterized by chronic free-floating anxiety, muscle tension, palpitation and insomnia. It has been proposed that there is chronic central hypersecretion of noradrenaline in Generalized Anxiety Disorder, with consequent hyporesponsiveness of central post-synaptic receptors. With regards to other disorders, it has been suggested that there is noradrenergic involvement or derangement, but a more specific hypothesis has not been enunciated. This paper reviews the evidence for noradrenergic dysfunction in anxiety disorders, derived from indirect measures of noradrenergic function in clinical populations.

  6. The Role of the Central Noradrenergic System in Behavioral Inhibition

    PubMed Central

    Stone, Eric A.; Lin, Yan; Sarfraz, Yasmeen; Quartermain, David

    2011-01-01

    Although the central noradrenergic system has been shown to be involved in a number of behavioral and neurophysiological processes, the relation of these to its role in depressive illness has been difficult to define. The present review discusses the hypothesis that one of its chief functions that may be related to affective illness is the inhibition of behavioral activation, a prominent symptom of the disorder. This hypothesis is found to be consistent with most previous neuropsychopharmacological and immunohistochemical experiments on active behavior in rodents in a variety of experimental conditions using manipulation of neurotransmission at both locus coeruleus and forebrain adrenergic receptors. The findings support a mechanism in which high rates of noradrenergic neural activity suppress the neural activity of principal neurons in forebrain regions mediating active behavior. The suppression may be mediated through postsynaptic galaninergic and adrenergic receptors, and via the release of corticotrophin-releasing hormone. The hypothesis is consistent with clinical evidence for central noradrenergic system hyperactivity in depressives and with the view that this hyperactivity is a contributing etiological factor in the disorder. A similar mechanism may underlie the ability of the noradrenergic system to suppress seizure activity suggesting that inhibition of the spread of neural activation may be a unifying function. PMID:21315760

  7. Pharmacological Modulation of Noradrenergic Arousal Circuitry Disrupts Functional Connectivity of the Locus Ceruleus in Humans

    PubMed Central

    Song, Andrew H.

    2017-01-01

    State-dependent activity of locus ceruleus (LC) neurons has long suggested a role for noradrenergic modulation of arousal. However, in vivo insights into noradrenergic arousal circuitry have been constrained by the fundamental inaccessibility of the human brain for invasive studies. Functional magnetic resonance imaging (fMRI) studies performed during site-specific pharmacological manipulations of arousal levels may be used to study brain arousal circuitry. Dexmedetomidine is an anesthetic that alters the level of arousal by selectively targeting α2 adrenergic receptors on LC neurons, resulting in reduced firing rate and norepinephrine release. Thus, we hypothesized that dexmedetomidine-induced altered arousal would manifest with reduced functional connectivity between the LC and key brain regions involved in the regulation of arousal. To test this hypothesis, we acquired resting-state fMRI data in right-handed healthy volunteers 18–36 years of age (n = 15, 6 males) at baseline, during dexmedetomidine-induced altered arousal, and recovery states. As previously reported, seed-based resting-state fMRI analyses revealed that the LC was functionally connected to a broad network of regions including the reticular formation, basal ganglia, thalamus, posterior cingulate cortex (PCC), precuneus, and cerebellum. Functional connectivity of the LC to only a subset of these regions (PCC, thalamus, and caudate nucleus) covaried with the level of arousal. Functional connectivity of the PCC to the ventral tegmental area/pontine reticular formation and thalamus, in addition to the LC, also covaried with the level of arousal. We propose a framework in which the LC, PCC, thalamus, and basal ganglia comprise a functional arousal circuitry. SIGNIFICANCE STATEMENT Electrophysiological studies of locus ceruleus (LC) neurons have long suggested a role for noradrenergic mechanisms in mediating arousal. However, the fundamental inaccessibility of the human brain for invasive studies has

  8. α(2) noradrenergic receptor suppressed CaMKII signaling in spinal dorsal horn of mice with inflammatory pain.

    PubMed

    Wang, Xin-Tai; Lian, Xia; Xu, Ying-Ming; Suo, Zhan-Wei; Yang, Xian; Hu, Xiao-Dong

    2014-02-05

    Intrathecal application of α2 noradrenergic receptor agonists effectively alleviates the pathological pain induced by peripheral tissue injury. However, the spinal antinociceptive mechanisms of α2 noradrenergic receptors remain to be characterized. The present study performed immunohistochemistry and western blot to elucidate the signaling pathway initiated by α2 noradrenergic receptors in spinal dorsal horn of mice, and identified calcium/calmodulin-dependent protein kinase II (CaMKII) as an important target for noradrenergic suppression of inflammatory pain. Our data showed that intraplantar injection of Complete Freund's Adjuvant (CFA) substantially enhanced CaMKII autophosphorylation at Threonine 286, which could be abolished by intrathecal administration of α2 noradrenergic receptor agonist clonidine. Gi protein-coupled α2 noradrenergic receptor might inhibit cAMP-dependent protein kinase (PKA) to disturb CaMKII signaling. We found that pharmacological activation of PKA in intact mice also enhanced spinal CaMKII autophosphorylation level, which was completely antagonized by clonidine. Moreover, direct PKA inhibition in CFA-injected mice mimicked the suppressive effect of α2 noradrenergic receptors on CaMKII. PKA inhibition has been shown to downregulate CaMKII by enhancing protein phosphatase activity. Consistent with this notion, spinal treatment with protein phosphatase inhibitor okadaic acid ruled out clonidine-mediated CaMKII dephosphorylation in CFA-injected mice. Through PKA/protein phosphatase/CaMKII pathway, clonidine noticeably decreased CFA-evoked phosphorylation of N-methyl-d-aspartate subtype glutamate receptor GluN1 and GluN2B subunit as well as α-amino-3-hydroxy-5-methylisoxazole-4-propionic Acid subtype glutamate receptor GluA1 subunit. These data suggested that interference with CaMKII signaling might represent an important mechanism underlying noradrenergic suppression of inflammatory pain. Copyright © 2013 Elsevier B.V. All rights

  9. Noradrenergic dysregulation in the pathophysiology of PTSD.

    PubMed

    Hendrickson, Rebecca C; Raskind, Murray A

    2016-10-01

    A central role for noradrenergic dysregulation in the pathophysiology of post-traumatic stress disorder (PTSD) is increasingly suggested by both clinical and basic neuroscience research. Here, we integrate recent findings from clinical and animal research with the earlier literature. We first review the evidence for net upregulation of the noradrenergic system and its responsivity to stress in individuals with PTSD. Next, we trace the evidence that the α 1 noradrenergic receptor antagonist prazosin decreases many of the symptoms of PTSD from initial clinical observations, to case series, to randomized controlled trials. Finally, we review the basic science work that has begun to explain the mechanism for this efficacy, as well as to explore its possible limitations and areas for further advancement. We suggest a view of the noradrenergic system as a central, modifiable link in a network of interconnected stress-response systems, which also includes the amygdala and its modulation by medial prefrontal cortex. Particular attention is paid to the evidence for bidirectional signaling between noradrenaline and corticotropin-releasing factor (CRF) in coordinating these interconnected systems. The multiple different ways in which the sensitivity and reactivity of the noradrenergic system may be altered in PTSD are highlighted, as is the evidence for possible heterogeneity in the pathophysiology of PTSD between different individuals who appear clinically similar. We conclude by noting the importance moving forward of improved measures of noradrenergic functioning in clinical populations, which will allow better recognition of clinical heterogeneity and further assessment of the functional implications of different aspects of noradrenergic dysregulation. Published by Elsevier Inc.

  10. Hindbrain A2 noradrenergic neuron adenosine 5'-monophosphate-activated protein kinase activation, upstream kinase/phosphorylase protein expression, and receptivity to hormone and fuel reporters of short-term food deprivation are regulated by estradiol.

    PubMed

    Briski, Karen P; Alenazi, Fahaad S H; Shakya, Manita; Sylvester, Paul W

    2017-07-01

    Estradiol (E) mitigates acute and postacute adverse effects of 12 hr-food deprivation (FD) on energy balance. Hindbrain 5'-monophosphate-activated protein kinase (AMPK) regulates hyperphagic and hypothalamic metabolic neuropeptide and norepinephrine responses to FD in an E-dependent manner. Energy-state information from AMPK-expressing hindbrain A2 noradrenergic neurons shapes neural responses to metabolic imbalance. Here we investigate the hypothesis that FD causes divergent changes in A2 AMPK activity in E- vs. oil (O)-implanted ovariectomized female rats, alongside dissimilar adjustments in circulating metabolic fuel (glucose, free fatty acids [FFA]) and energy deficit-sensitive hormone (corticosterone, glucagon, leptin) levels. FD decreased blood glucose in oil (O)- but not E-implanted ovariectomized female rats and elevated and reduced glucagon levels in O and E, respectively. FD decreased circulating leptin in O and E, but increased corticosterone and FFA concentrations in E only. Western blot analysis of laser-microdissected A2 neurons showed that glucocorticoid receptor type II and very-long-chain acyl-CoA synthetase 3 protein profiles were amplified in FD/E vs. FD/O. A2 total AMPK protein was elevated without change in activity in FD/O, whereas FD/E exhibited increased AMPK activation along with decreased upstream phosphatase expression. The catecholamine biosynthetic enzyme dopamine-β-hydroxylase (DβH) was increased in FD/O but not FD/E A2 cells. The data show discordance between A2 AMPK activation and glycemic responses to FD; sensor activity was refractory to glucose decrements in FD/O but augmented in FD/E despite stabilized glucose and elevated FFA levels. E-dependent amplification of AMPK activity may reflect adaptive conversion to fatty acid oxidation and/or glucocorticoid stimulation. FD augmentation of A2 DβH protein profiles in FD/O but not FD/E animals suggests that FD may correspondingly regulate NE synthesis vs. metabolism/release in the

  11. Adrenoceptor-Mediated Post- and Pre-Synaptic Regulations of the Reticulospinal Neurons in Rat Caudal Pontine Reticular Nucleus.

    PubMed

    Yang, Nian; Qiao, Qi-Cheng; Liu, Yu-Hui; Zhang, Ji-Qiang; Hu, Zhi-An; Zhang, Jun

    2016-12-01

    The central noradrenergic system participates in diverse nervous functions. Nevertheless, our knowledge of the action of adrenoceptors in motor regulation is still lacking. Intriguingly, reticulospinal neurons in the caudal pontine reticular nucleus (PnC) receive fairly dense noradrenergic innervation and play an important role in motor control. Here, after demonstrating the expression of α1- and α2-adrenoceptors in the PnC, we found that noradrenaline elicited a post-synaptic effect (inward or outward whole-cell current at -70 mV holding) on PnC reticulospinal neurons. The α1- and α2-adrenoceptors were co-expressed in individual PnC reticulospinal neurons to mediate an inward and an outward current component at -70 mV holding, respectively, which, when superposed, produced the overall post-synaptic effects of noradrenaline (NA). More importantly, the activation of post-synaptic α1- or α2-adrenoceptors indeed exerted opposing modulations (excitation vs. inhibition) on the firing activities of individual PnC reticulospinal neurons. Furthermore, the activation and inhibition of the Na + -permeable non-selective cationic conductance (NSCC) were demonstrated to be coupled to α1- and α2-adrenoceptors, respectively. Additionally, the activation of α2-adrenoceptors activated K + conductance. Pre-synaptically, the α2-adrenoceptors were expressed to attenuate the miniature excitatory postsynaptic current (mEPSC) in PnC reticulospinal neurons, but not to affect the miniature inhibitory postsynaptic current (mIPSC). Consistently, the evoked EPSC in PnC reticulospinal neurons was suppressed after the activation of pre-synaptic α2-adrenoceptors. Thus, the excitatory input and post-synaptic dynamics of PnC reticulospinal neurons are indeed intricately modulated by the activation of α1- and α2-adrenoceptors, through which motor control may be regulated in an adaptive manner by the central noradrenergic system.

  12. Deepened extinction following compound stimulus presentation: Noradrenergic modulation

    PubMed Central

    Janak, Patricia H.; Corbit, Laura H.

    2011-01-01

    Behavioral extinction is an active form of new learning involving the prediction of nonreward where reward has previously been present. The expression of extinction learning can be disrupted by the presentation of reward itself or reward-predictive stimuli (reinstatement) as well as the passage of time (spontaneous recovery) or contextual changes (renewal). The following experiments replicated the demonstration that presenting multiple previously rewarded stimuli in compound during extinction enhances extinction learning. To explore the pharmacological basis for this we next examined the effects of pharmacological treatments that either facilitated or blocked noradrenergic activity to test the hypothesis that increased noradrenergic activity at the time of extinction training would improve, whereas blockade of noradrenergic activity would impair the extinction of appetitive stimulus–reward memories. Different groups of rats were trained in a discriminative stimulus paradigm to lever-press for food reward. Once stable responding was achieved, responding was extinguished for 2 d. Prior to a third extinction session, rats received systemic administration of either saline, yohimbine (α2 antagonist), atomoxetine (norepinephrine reuptake inhibitor), or propranolol (β-receptor antagonist). Spontaneous recovery of responding to the stimuli was tested 4 wk later. Our results indicate that increasing noradrenergic activity during extinction augments extinction learning resulting in less recovery of responding at test. These results have important implications for models of relapse to drug seeking and the development of extinction-based therapies. PMID:21224211

  13. Some lumbar sympathetic neurons develop a glutamatergic phenotype after peripheral axotomy with a note on VGLUT2-positive perineuronal baskets

    PubMed Central

    Brumovsky, Pablo R.; Seroogy, Kim B.; Lundgren, Kerstin H.; Watanabe, Masahiko; Hökfelt, Tomas; Gebhart, G. F.

    2011-01-01

    Glutamate is the main excitatory neurotransmitter in the nervous system, including in primary afferent neurons. However, to date a glutamatergic phenotype of autonomic neurons has not been described. Therefore, we explored the expression of vesicular glutamate transporters (VGLUTs) type 1, 2 and 3 in lumbar sympathetic chain (LSC) and major pelvic ganglion (MPG) of naïve BALB/C mice, as well as after pelvic nerve axotomy (PNA), using immunohistochemistry and in situ hybridization. Colocalization with activating transcription factor-3 (ATF-3), tyrosine hydroxylase (TH), vesicular acetylcholine transporter (VAChT) and calcitonin generelated peptide was also examined. Sham-PNA, sciatic nerve axotomy (SNA) or naïve mice were included. In naïve mice, VGLUT2-like immunoreactivity (LI) was only detected in fibers and varicosities in LSC and MPG; no ATF-3-immunoreactive (IR) neurons were visible. In contrast, PNA induced upregulation of VGLUT2 protein and transcript, as well as of ATF-3-LI in subpopulations of LSC neurons. Interestingly, VGLUT2-IR LSC neurons coexpressed ATF-3, and often lacked the noradrenergic marker TH. SNA only increased VGLUT2 protein and transcript in scattered LSC neurons. Neither PNA nor SNA upregulated VGLUT2 in MPG neurons. We also found perineuronal baskets immunoreactive either for VGLUT2 or the acetylcholinergic marker VAChT in non-PNA MPGs, usually around TH-IR neurons. VGLUT1-LI was restricted to some varicosities in MPGs, was absent in LSCs, and remained largely unaffected by PNA or SNA. This was confirmed by the lack of expression of VGLUT1 or VGLUT3 mRNAs in LSCs, even after PNA or SNA. Taken together, axotomy of visceral and non-visceral nerves results in a glutamatergic phenotype of some LSC neurons. In addition, we show previously non-described MPG perineuronal glutamatergic baskets. PMID:21596036

  14. CRH engagement of the locus coeruleus noradrenergic system mediates stress-induced anxiety

    PubMed Central

    McCall, Jordan G.; Al-Hasani, Ream; Siuda, Edward R.; Hong, Daniel Y.; Norris, Aaron J.; Ford, Christopher P.; Bruchas, Michael R.

    2015-01-01

    Summary The locus coeruleus noradrenergic (LC-NE) system is one of the first systems engaged following a stressful event. While numerous groups have demonstrated that LC-NE neurons are activated by many different stressors, the underlying neural circuitry and the role of this activity in generating stress-induced anxiety has not been elucidated. Using a combination of in vivo chemogenetics, optogenetics, and retrograde tracing we determine that increased tonic activity of the LC-NE system is necessary and sufficient for stress-induced anxiety and aversion. Selective inhibition of LC-NE neurons during stress prevents subsequent anxiety-like behavior. Exogenously increasing tonic, but not phasic, activity of LC-NE neurons is alone sufficient for anxiety-like and aversive behavior. Furthermore, endogenous corticotropin releasing hormone+ (CRH+) LC inputs from the amygdala increase tonic LC activity, inducing anxiety-like behaviors. These studies position the LC-NE system as a critical mediator of acute stress-induced anxiety and offer a potential intervention for preventing stress-related affective disorders. PMID:26212712

  15. Restoring Spinal Noradrenergic Inhibitory Tone Attenuates Pain Hypersensitivity in a Rat Model of Parkinson's Disease

    PubMed Central

    Wang, Bing; Chen, Li-Hua

    2016-01-01

    In the present study, we investigated whether restoring descending noradrenergic inhibitory tone can attenuate pain in a PD rat model, which was established by stereotaxic infusion of 6-hydroxydopamine (6-OHDA) into the bilateral striatum (CPu). PD rats developed thermal and mechanical hypersensitivity at the 4th week after surgery. HPLC analysis showed that NE content, but not dopamine or 5-HT, significantly decreased in lumbar spinal cord in PD rats. Additional noradrenergic depletion by injection of N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4) aggravated pain hypersensitivity in PD rats. At the 5th week after injection of 6-OHDA, systemic treatment with pharmacological norepinephrine (NE) precursor droxidopa (L-DOPS) or α2 adrenoceptor agonist clonidine significantly attenuated thermal and mechanical pain hypersensitivity in PD rats. Furthermore, application of norepinephrine (NE) and 5-hydroxytryptamine (5-HT) reuptake inhibitors duloxetine, but not 5-HT selective reuptake inhibitors sertraline, significantly inhibited thermal and mechanical pain hypersensitivity in PD rats. Systemic administration of Madopar (L-DOPA) or the D2/D3 agonist pramipexole slightly inhibited the thermal, but not mechanical, hypersensitivity in PD rats. Thus, our study revealed that impairment of descending noradrenergic system may play a key role in PD-associated pain and restoring spinal noradrenergic inhibitory tone may serve as a novel strategy to manage PD-associated pain. PMID:27747105

  16. Noradrenaline and dopamine neurons in the reward/effort trade-off: a direct electrophysiological comparison in behaving monkeys.

    PubMed

    Varazzani, Chiara; San-Galli, Aurore; Gilardeau, Sophie; Bouret, Sebastien

    2015-05-20

    Motivation determines multiple aspects of behavior, including action selection and energization of behavior. Several components of the underlying neural systems have been examined closely, but the specific role of the different neuromodulatory systems in motivation remains unclear. Here, we compare directly the activity of dopaminergic neurons from the substantia nigra pars compacta and noradrenergic neurons from the locus coeruleus in monkeys performing a task manipulating the reward/effort trade-off. Consistent with previous reports, dopaminergic neurons encoded the expected reward, but we found that they also anticipated the upcoming effort cost in connection with its negative influence on action selection. Conversely, the firing of noradrenergic neurons increased with both pupil dilation and effort production in relation to the energization of behavior. Therefore, this work underlines the contribution of dopamine to effort-based decision making and uncovers a specific role of noradrenaline in energizing behavior to face challenges. Copyright © 2015 the authors 0270-6474/15/357866-12$15.00/0.

  17. CRH Engagement of the Locus Coeruleus Noradrenergic System Mediates Stress-Induced Anxiety.

    PubMed

    McCall, Jordan G; Al-Hasani, Ream; Siuda, Edward R; Hong, Daniel Y; Norris, Aaron J; Ford, Christopher P; Bruchas, Michael R

    2015-08-05

    The locus coeruleus noradrenergic (LC-NE) system is one of the first systems engaged following a stressful event. While numerous groups have demonstrated that LC-NE neurons are activated by many different stressors, the underlying neural circuitry and the role of this activity in generating stress-induced anxiety has not been elucidated. Using a combination of in vivo chemogenetics, optogenetics, and retrograde tracing, we determine that increased tonic activity of the LC-NE system is necessary and sufficient for stress-induced anxiety and aversion. Selective inhibition of LC-NE neurons during stress prevents subsequent anxiety-like behavior. Exogenously increasing tonic, but not phasic, activity of LC-NE neurons is alone sufficient for anxiety-like and aversive behavior. Furthermore, endogenous corticotropin-releasing hormone(+) (CRH(+)) LC inputs from the amygdala increase tonic LC activity, inducing anxiety-like behaviors. These studies position the LC-NE system as a critical mediator of acute stress-induced anxiety and offer a potential intervention for preventing stress-related affective disorders. Copyright © 2015 Elsevier Inc. All rights reserved.

  18. Locus coeruleus to basolateral amygdala noradrenergic projections promote anxiety-like behavior.

    PubMed

    McCall, Jordan G; Siuda, Edward R; Bhatti, Dionnet L; Lawson, Lamley A; McElligott, Zoe A; Stuber, Garret D; Bruchas, Michael R

    2017-07-14

    Increased tonic activity of locus coeruleus noradrenergic (LC-NE) neurons induces anxiety-like and aversive behavior. While some information is known about the afferent circuitry that endogenously drives this neural activity and behavior, the downstream receptors and anatomical projections that mediate these acute risk aversive behavioral states via the LC-NE system remain unresolved. Here we use a combination of retrograde tracing, fast-scan cyclic voltammetry, electrophysiology, and in vivo optogenetics with localized pharmacology to identify neural substrates downstream of increased tonic LC-NE activity in mice. We demonstrate that photostimulation of LC-NE fibers in the BLA evokes norepinephrine release in the basolateral amygdala (BLA), alters BLA neuronal activity, conditions aversion, and increases anxiety-like behavior. Additionally, we report that β-adrenergic receptors mediate the anxiety-like phenotype of increased NE release in the BLA. These studies begin to illustrate how the complex efferent system of the LC-NE system selectively mediates behavior through distinct receptor and projection-selective mechanisms.

  19. Evidence for a role of corticopetal, noradrenergic systems in the development of executive function.

    PubMed

    Mokler, David J; Miller, Christine E; McGaughy, Jill A

    2017-09-01

    Adolescence is a period during which many aspects of executive function are maturing. Much of the literature has focused on discrepancies between sub-cortical and cortical development that is hypothesized to lead to over-processing of reinforcement related stimuli unchecked by fully matured response inhibition. Specifically, maturation of sub-cortical dopaminergic systems that terminate in the nucleus accumbens has been suggested to occur prior to the full maturation of corticopetal dopaminergic systems. However, converging evidence supports the hypothesis that many aspects of cognitive control are critically linked to cortical noradrenergic systems, that the effectiveness of drugs used to treat disorders of executive function, e.g. ADHD, may result primarily from increases in cortical norepinephrine (NE) and that cortical noradrenergic systems mature across adolescence. However, little attention has been given to the development of this system during adolescence or to its influence in executive function. In the present paper, we discuss the developmental trajectory of the noradrenergic system of the forebrain, highlight the interactions between noradrenergic and dopaminergic systems, and highlight the contribution of the immature corticopetal noradrenergic systems in the ontogeny of several aspects of executive function. Finally we compare data from adolescent rats to those gathered after selective depletion of NE in sub-regions of the prefrontal cortex with an emphasis on the similarities in performance of NE lesioned rats and adolescents. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Locus coeruleus to basolateral amygdala noradrenergic projections promote anxiety-like behavior

    PubMed Central

    McCall, Jordan G; Siuda, Edward R; Bhatti, Dionnet L; Lawson, Lamley A; McElligott, Zoe A; Stuber, Garret D; Bruchas, Michael R

    2017-01-01

    Increased tonic activity of locus coeruleus noradrenergic (LC-NE) neurons induces anxiety-like and aversive behavior. While some information is known about the afferent circuitry that endogenously drives this neural activity and behavior, the downstream receptors and anatomical projections that mediate these acute risk aversive behavioral states via the LC-NE system remain unresolved. Here we use a combination of retrograde tracing, fast-scan cyclic voltammetry, electrophysiology, and in vivo optogenetics with localized pharmacology to identify neural substrates downstream of increased tonic LC-NE activity in mice. We demonstrate that photostimulation of LC-NE fibers in the BLA evokes norepinephrine release in the basolateral amygdala (BLA), alters BLA neuronal activity, conditions aversion, and increases anxiety-like behavior. Additionally, we report that β-adrenergic receptors mediate the anxiety-like phenotype of increased NE release in the BLA. These studies begin to illustrate how the complex efferent system of the LC-NE system selectively mediates behavior through distinct receptor and projection-selective mechanisms. DOI: http://dx.doi.org/10.7554/eLife.18247.001 PMID:28708061

  1. Noradrenergic Dysfunction in Alzheimer's and Parkinson's Diseases-An Overview of Imaging Studies.

    PubMed

    Peterson, Andrew C; Li, Chiang-Shan R

    2018-01-01

    Noradrenergic dysfunction contributes to cognitive impairment in Alzheimer's Disease (AD) and Parkinson's Disease (PD). Conventional therapeutic strategies seek to enhance cholinergic and dopaminergic neurotransmission in AD and PD, respectively, and few studies have examined noradrenergic dysfunction as a target for medication development. We review the literature of noradrenergic dysfunction in AD and PD with a focus on human imaging studies that implicate the locus coeruleus (LC) circuit. The LC sends noradrenergic projections diffusely throughout the cerebral cortex and plays a critical role in attention, learning, working memory, and cognitive control. The LC undergoes considerable degeneration in both AD and PD. Advances in magnetic resonance imaging have facilitated greater understanding of how structural and functional alteration of the LC may contribute to cognitive decline in AD and PD. We discuss the potential roles of the noradrenergic system in the pathogenesis of AD and PD with an emphasis on postmortem anatomical studies, structural MRI studies, and functional MRI studies, where we highlight changes in LC connectivity with the default mode network (DMN). LC degeneration may accompany deficient capacity in suppressing DMN activity and increasing saliency and task control network activities to meet behavioral challenges. We finish by proposing potential and new directions of research to address noradrenergic dysfunction in AD and PD.

  2. A53T-α-synuclein overexpression in murine locus coeruleus induces Parkinson's disease-like pathology in neurons and glia.

    PubMed

    Henrich, Martin Timo; Geibl, Fanni Fruzsina; Lee, Bolam; Chiu, Wei-Hua; Koprich, James Benjamin; Brotchie, Jonathan Michael; Timmermann, Lars; Decher, Niels; Matschke, Lina Anita; Oertel, Wolfgang Hermann

    2018-05-10

    Degeneration of noradrenergic locus coeruleus neurons occurs during the prodromal phase of Parkinson's disease and contributes to a variety of non-motor symptoms, e.g. depression, anxiety and REM sleep behavior disorder. This study was designed to establish the first locus coeruleus α-synucleinopathy mouse model, which should provide sufficient information about the time-course of noradrenergic neurodegeneration, replicate cardinal histopathological features of the human Parkinson's disease neuropathology and finally lead to robust histological markers, which are sufficient to assess the pathological changes in a quantitative and qualitative way. We show that targeted viral vector-mediated overexpression of human mutant A53T-α-synuclein in vivo in locus coeruleus neurons of wild-type mice resulted in progressive noradrenergic neurodegeneration over a time frame of 9 weeks. Observed neuronal cell loss was accompanied by progressive α-synuclein phosphorylation, formation of proteinase K-resistant α-synuclein-aggregates, accumulation of Ubi-1- and p62-positive inclusions in microglia and induction of progressive micro- and astrogliosis. Apart from this local pathology, abundant α-synuclein-positive axons were found in locus coeruleus output regions, indicating rapid anterograde axonal transport of A53T-α-synuclein. Taken together, we present the first model of α-synucleinopathy in the murine locus coeruleus, replicating essential morphological features of human Parkinson's disease pathology. This new model may contribute to the research on prodromal Parkinson's disease, in respect to pathophysiology and the development of disease-modifying therapy.

  3. Lesion of the locus coeruleus aggravates dopaminergic neuron degeneration by modulating microglial function in mouse models of Parkinson׳s disease.

    PubMed

    Yao, Ning; Wu, Yanhong; Zhou, Yan; Ju, Lili; Liu, Yujun; Ju, Rongkai; Duan, Deyi; Xu, Qunyuan

    2015-11-02

    The degeneration of noradrenergic neurons in the locus coeruleus (LC) commonly occurs in patients with Parkinson's disease (PD), which is characterized by a selective injury of dopaminergic neurons in the substantia nigra (SN). The pathological impact of the LC on the SN in the disease is unknown. In the present study, we used a noradrenergic toxin, N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP4), to deplete noradrenaline (NA) derived from the LC to explore its influence on degeneration or injury of dopaminergic neurons in the SN in mouse model produced by intraperitoneal injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) or lipopolysaccharide (LPS). Our results demonstrated that lesion of the LC could change microglial function in the brain, which led to enhanced or prolonged expression of pro-inflammatory cytokines, diminished neurotrophic factors, and weakened ability of anti-oxidation in the SN. The in vitro experiments further confirmed that NA could reduce the inflammatory reaction of microglia. The selective injury of dopaminergic neurons by inflammation, however, was due to the inflammation in different brain regions rather than the depletion of NA. Our results indicate that the lesion in the LC is an important factor in promoting dopaminergic neuron degeneration by impacting the function of microglia in the midbrain. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Vagus nerve stimulation improves locomotion and neuronal populations in a model of Parkinson's disease.

    PubMed

    Farrand, Ariana Q; Helke, Kristi L; Gregory, Rebecca A; Gooz, Monika; Hinson, Vanessa K; Boger, Heather A

    Parkinson's disease (PD) is a progressive, neurodegenerative disorder with no disease-modifying therapies, and symptomatic treatments are often limited by debilitating side effects. In PD, locus coeruleus noradrenergic (LC-NE) neurons degenerate prior to substantia nigra dopaminergic (SN-DA) neurons. Vagus nerve stimulation (VNS) activates LC neurons, and decreases pro-inflammatory markers, allowing improvement of LC targets, making it a potential PD therapeutic. To assess therapeutic potential of VNS in a PD model. To mimic the progression of PD degeneration, rats received a systemic injection of noradrenergic neurotoxin DSP-4, followed one week later by bilateral intrastriatal injection of dopaminergic neurotoxin 6-hydroxydopamine. At this time, a subset of rats also had vagus cuffs implanted. After eleven days, rats received a precise VNS regimen twice a day for ten days, and locomotion was measured during each afternoon session. Immediately following final stimulation, rats were euthanized, and left dorsal striatum, bilateral SN and LC were sectioned for immunohistochemical detection of monoaminergic neurons (tyrosine hydroxylase, TH), α-synuclein, astrocytes (GFAP) and microglia (Iba-1). VNS significantly increased locomotion of lesioned rats. VNS also resulted in increased expression of TH in striatum, SN, and LC; decreased SN α-synuclein expression; and decreased expression of glial markers in the SN and LC of lesioned rats. Additionally, saline-treated rats after VNS, had higher LC TH and lower SN Iba-1. Our findings of increased locomotion, beneficial effects on LC-NE and SN-DA neurons, decreased α-synuclein density in SN TH-positive neurons, and neuroinflammation suggest VNS has potential as a novel PD therapeutic. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. Noradrenergic Stimulation Impairs Memory Generalization in Women.

    PubMed

    Kluen, Lisa Marieke; Agorastos, Agorastos; Wiedemann, Klaus; Schwabe, Lars

    2017-07-01

    Memory generalization is essential for adaptive decision-making and action. Our ability to generalize across past experiences relies on medial-temporal lobe structures, known to be highly sensitive to stress. Recent evidence suggests that stressful events may indeed interfere with memory generalization. Yet, the mechanisms involved in this generalization impairment are unknown. We tested here whether a pharmacological elevation of major stress mediators-noradrenaline and glucocorticoids-is sufficient to disrupt memory generalization. In a double-blind, placebo-controlled design, healthy men and women received orally a placebo, hydrocortisone, the α2-adrenoceptor antagonist yohimbine that leads to increased noradrenergic stimulation, or both drugs, before they completed an associative learning task probing memory generalization. Drugs left learning performance intact. Yohimbine, however, led to a striking generalization impairment in women, but not in men. Hydrocortisone, in turn, had no effect on memory generalization, neither in men nor in women. The present findings indicate that increased noradrenergic activity, but not cortisol, is sufficient to disrupt memory generalization in a sex-specific manner, with relevant implications for stress-related mental disorders characterized by generalization deficits.

  6. Independent inputs by VGLUT2- and VGLUT3-positive glutamatergic terminals onto rat sympathetic preganglionic neurons.

    PubMed

    Nakamura, Kazuhiro; Wu, Sheng-Xi; Fujiyama, Fumino; Okamoto, Keiko; Hioki, Hiroyuki; Kaneko, Takeshi

    2004-03-01

    To characterize glutamatergic axon terminals onto sympathetic preganglionic neurons (SPNs), we visualized immunohistochemically three vesicular glutamate transporters (VGLUTs) in the intermediolateral cell column (IML) of rat thoracic spinal cord. VGLUT2 and VGLUT3 immunoreactivities but not VGLUT1 immunoreactivity were distributed in the IML and found in terminals making asymmetric synapses and apposed to dendrites immunopositive for choline acetyltransferase, an SPN marker. VGLUT2 and VGLUT3 immunoreactivities were not co-localized with each other. A population of VGLUT2-immunoreactive but not VGLUT3-immunoreactive terminals were adrenergic or noradrenergic. Some of VGLUT3-immunoreactive but not VGLUT2-immunoreactive terminals contained serotonin. These results indicate at least two independent glutamatergic terminal populations, which include a distinct monoaminergic subpopulation, making excitatory inputs onto SPNs. Copyright 2004 Lippincott Williams & Wilkins

  7. Fear conditioning selectively disrupts noradrenergic facilitation of GABAergic inhibition in the basolateral amygdala.

    PubMed

    Skelly, M J; Ariwodola, O J; Weiner, J L

    2017-02-01

    Inappropriate fear memory formation is symptomatic of many psychopathologies, and delineating the neurobiology of non-pathological fear learning may provide critical insight into treating these disorders. Fear memory formation is associated with decreased inhibitory signaling in the basolateral amygdala (BLA), and disrupted noradrenergic signaling may contribute to this decrease. BLA noradrenergic neurotransmission has been implicated in fear memory formation, and distinct adrenoreceptor (AR) subtypes modulate excitatory and inhibitory neurotransmission in this region. For example, α1-ARs promote GABA release from local inhibitory interneurons, while β3-ARs potentiate neurotransmission at lateral paracapsular (LPC) GABAergic synapses. Conversely, β1/2-ARs amplify excitatory signaling at glutamatergic synapses in the BLA. As increased BLA excitability promotes fear memory formation, we hypothesized that fear learning shifts the balanced regional effects of noradrenergic signaling toward excitation. To test this hypothesis, we used the fear-potentiated startle paradigm in combination with whole cell patch clamp electrophysiology to examine the effects of AR activation on BLA synaptic transmission following fear conditioning in male Long-Evans rats. We first demonstrated that inhibitory neurotransmission is decreased at both local and LPC synapses following fear conditioning. We next measured noradrenergic facilitation of BLA inhibitory signaling at local and LPC synapses using α1-and β3-AR agonists (1 μM A61603 and 10 μM BRL37344), and found that the ability of these agents to facilitate inhibitory neurotransmission is disrupted following fear conditioning. Conversely, we found that fear learning does not disrupt noradrenergic modulation of glutamatergic signaling via a β1/2-AR agonist (1 μM isoproterenol). Taken together, these studies suggest that fear learning increases BLA excitability by selectively disrupting the inhibitory effects of noradrenaline

  8. Fear Conditioning Selectively Disrupts Noradrenergic Facilitation of GABAergic Inhibition in the Basolateral Amygdala

    PubMed Central

    Skelly, M. J.; Ariwodola, O. J.; Weiner, J. L.

    2016-01-01

    Inappropriate fear memory formation is symptomatic of many psychopathologies, and delineating the neurobiology of non-pathological fear learning may provide critical insight into treating these disorders. Fear memory formation is associated with decreased inhibitory signaling in the basolateral amygdala (BLA), and disrupted noradrenergic signaling may contribute to this decrease. BLA noradrenergic neurotransmission has been implicated in fear memory formation, and distinct adrenoreceptor (AR) subtypes modulate excitatory and inhibitory neurotransmission in this region. For example, α1-ARs promote GABA release from local inhibitory interneurons, while β3-ARs potentiate neurotransmission at lateral paracapsular (LPC) GABAergic synapses. Conversely, β1/2-ARs amplify excitatory signaling at glutamatergic synapses in the BLA. As increased BLA excitability promotes fear memory formation, we hypothesized that fear learning shifts the balanced regional effects of noradrenergic signaling toward excitation. To test this hypothesis, we used the fear-potentiated startle paradigm in combination with whole cell patch clamp electrophysiology to examine the effects of AR activation on BLA synaptic transmission following fear conditioning in male Long-Evans rats. We first demonstrated that inhibitory neurotransmission is decreased at both local and LPC synapses following fear conditioning. We next measured noradrenergic facilitation of BLA inhibitory signaling at local and LPC synapses using α1- and β3-AR agonists (1μM A61603 and 10μM BRL37344), and found that the ability of these agents to facilitate inhibitory neurotransmission is disrupted following fear conditioning. Conversely, we found that fear learning does not disrupt noradrenergic modulation of glutamatergic signaling via a β1/2-AR agonist (1μM isoproterenol). Taken together, these studies suggest that fear learning increases BLA excitability by selectively disrupting the inhibitory effects of noradrenaline. PMID

  9. Noradrenergic System in Down Syndrome and Alzheimer's Disease A Target for Therapy.

    PubMed

    Phillips, Cristy; Fahimi, Atoossa; Das, Devsmita; Mojabi, Fatemeh S; Ponnusamy, Ravikumar; Salehi, Ahmad

    2016-01-01

    Locus coeruleus (LC) neurons in the brainstem send extensive noradrenergic (NE)-ergic terminals to the majority of brain regions, particularly those involved in cognitive function. Both Alzheimer's disease (AD) and Down syndrome (DS) are characterized by similar pathology including significant LC degeneration and dysfunction of the NE-ergic system. Extensive loss of NE-ergic terminals has been linked to alterations in brain regions vital for cognition, mood, and executive function. While the mechanisms by which NE-ergic abnormalities contribute to cognitive dysfunction are not fully understood, emergent evidence suggests that rescue of NE-ergic system can attenuate neuropathology and cognitive decline in both AD and DS. Therapeutic strategies to enhance NE neurotransmission have undergone limited testing. Among those deployed to date are NE reuptake inhibitors, presynaptic α-adrenergic receptor antagonists, NE prodrugs, and β-adrenergic agonists. Here we examine alterations in the NE-ergic system in AD and DS and suggest that NE-ergic system rescue is a plausible treatment strategy for targeting cognitive decline in both disorders.

  10. Metformin normalizes the structural changes in glycogen preceding prediabetes in mice overexpressing neuropeptide Y in noradrenergic neurons.

    PubMed

    Ailanen, Liisa; Bezborodkina, Natalia N; Virtanen, Laura; Ruohonen, Suvi T; Malova, Anastasia V; Okovityi, Sergey V; Chistyakova, Elizaveta Y; Savontaus, Eriika

    2018-04-01

    Hepatic insulin resistance and increased gluconeogenesis are known therapeutic targets of metformin, but the role of hepatic glycogen in the pathogenesis of diabetes is less clear. Mouse model of neuropeptide Y (NPY) overexpression in noradrenergic neurons (OE-NPY D βH ) with a phenotype of late onset obesity, hepatosteatosis, and prediabetes was used to study early changes in glycogen structure and metabolism preceding prediabetes. Furthermore, the effect of the anti-hyperglycemic agent, metformin (300 mg/kg/day/4 weeks in drinking water), was assessed on changes in glycogen metabolism, body weight, fat mass, and glucose tolerance. Glycogen structure was characterized by cytofluorometric analysis in isolated hepatocytes and mRNA expression of key enzymes by qPCR. OE-NPY D βH mice displayed decreased labile glycogen fraction relative to stabile fraction (the intermediate form of glycogen) suggesting enhanced glycogen cycling. This was supported by decreased filling of glucose residues in the 10th outer tier of the glycogen molecule, which suggests accelerated glycogen phosphorylation. Metformin reduced fat mass gain in both genotypes, but glucose tolerance was improved mostly in wild-type mice. However, metformin inhibited glycogen accumulation and normalized the ratio between glycogen structures in OE-NPY D βH mice indicating decreased glycogen synthesis. Furthermore, the presence of glucose residues in the 11th tier together with decreased glycogen phosphorylase expression suggested inhibition of glycogen degradation. In conclusion, structural changes in glycogen of OE-NPY D βH mice point to increased glycogen metabolism, which may predispose them to prediabetes. Metformin treatment normalizes these changes and suppresses both glycogen synthesis and phosphorylation, which may contribute to its preventive effect on the onset of diabetes.

  11. The noradrenergic system in pathological anxiety: a focus on panic with relevance to generalized anxiety and phobias.

    PubMed

    Sullivan, G M; Coplan, J D; Kent, J M; Gorman, J M

    1999-11-01

    Over the past three decades of psychiatric research, abnormalities in the noradrenergic system have been identified in particular anxiety disorders such as panic disorder. Simultaneously, neuroscience research on fear pathways and the stress response have delineated central functions for the noradrenergic system. This review focuses on the noradrenergic system in anxiety spectrum disorders such as panic disorder, generalized anxiety disorder, and phobias for the purpose of elucidating current conceptualizations of the pathophysiologies. Neuroanatomic pathways that are theoretically relevant in anxiogenesis are discussed and the implications for treatment reviewed.

  12. The noradrenergic paradox: implications in the management of depression and anxiety

    PubMed Central

    Montoya, Alonso; Bruins, Robert; Katzman, Martin A; Blier, Pierre

    2016-01-01

    Both major depressive disorder and the anxiety disorders are major causes of disability and markedly contribute to a significant global burden of the disease worldwide. In part because of the significant socioeconomic burden associated with these disorders, theories have been developed to specifically build clinical treatment approaches. One such theory, the monoaminergic hypothesis, has led to the development of several generations of selective and nonselective inhibitors of transporters of serotonin and norepinephrine, with the goal of augmenting monoaminergic transmission. These efforts have led to considerable success in the development of antidepressant therapeutics. However, there is a strong correlation between enhanced noradrenergic activity and fear and anxiety. Consequently, some physicians have expressed concerns that the same enhanced noradrenergic activity that alleviates depression could also promote anxiety. The fact that the serotonergic and noradrenergic reuptake inhibitors are successfully used in the treatment of anxiety and panic disorders seems paradoxical. This review was undertaken to determine if any clinical evidence exists to show that serotonergic and noradrenergic reuptake inhibitors can cause anxiety. The PubMed, EMBASE, and Cochrane Library databases were searched, and the results limited to randomized, double-blind, placebo-controlled studies performed in nongeriatric adults and with clear outcome measures were reported. Based on these criteria, a total of 52 studies were examined. Patients in these studies suffered from depression or anxiety disorders (generalized and social anxiety disorders, panic disorder, and posttraumatic stress disorder). The large majority of these studies employed venlafaxine or duloxetine, and the remainder used tri-cyclic antidepressants, atomoxetine, or reboxetine. All the studies reported clinically significant alleviation of depressive and/or anxious symptoms by these therapeutics. In none of these

  13. Stimulation of the noradrenergic system during memory formation impairs extinction learning but not the disruption of reconsolidation.

    PubMed

    Soeter, Marieke; Kindt, Merel

    2012-04-01

    The noradrenergic system plays a critical role in the 'consolidation' of emotional memory. If we are to target 'reconsolidation' in patients with anxiety disorders, the noradrenergic strengthening of fear memory should not impair the disruption of reconsolidation. In Experiment I, we addressed this issue using a differential fear conditioning procedure allowing selective reactivation of one of two fear associations. First, we strengthened fear memory by administering an α(2)-adrenergic receptor antagonist (ie, yohimbine HCl; double-blind placebo-controlled study) 30 min before acquisition (time for peak value yohimbine HCl <1 h). Next, the reconsolidation of one of the fear associations was manipulated by administering a β-adrenergic receptor antagonist (ie, propranolol HCl) 90 min before its selective reactivation (time for peak value propranolol HCl <2 h). In Experiment II, we administered propranolol HCl after reactivation of the memory to rule out a possible effect of the pharmacological manipulation on the memory retrieval itself. The excessive release of noradrenaline during memory formation not only delayed the process of extinction 48 h later, but also triggered broader fear generalization. Yet, the β-adrenergic receptor blocker during reconsolidation selectively 'neutralized' the fear-arousing aspects of the noradrenergic-strengthened memory and undermined the generalization of fear. We observed a similar reduction in fear responding when propranolol HCl was administered after reactivation of the memory. The present findings demonstrate the involvement of noradrenergic modulation in the formation as well as generalization of human fear memory. Given that the noradrenergic strengthening of fear memory impaired extinction learning but not the disruption of reconsolidation, our findings may have implications for the treatment of anxiety disorders.

  14. Noradrenergic modulation of neural erotic stimulus perception.

    PubMed

    Graf, Heiko; Wiegers, Maike; Metzger, Coraline Danielle; Walter, Martin; Grön, Georg; Abler, Birgit

    2017-09-01

    We recently investigated neuromodulatory effects of the noradrenergic agent reboxetine and the dopamine receptor affine amisulpride in healthy subjects on dynamic erotic stimulus processing. Whereas amisulpride left sexual functions and neural activations unimpaired, we observed detrimental activations under reboxetine within the caudate nucleus corresponding to motivational components of sexual behavior. However, broadly impaired subjective sexual functioning under reboxetine suggested effects on further neural components. We now investigated the same sample under these two agents with static erotic picture stimulation as alternative stimulus presentation mode to potentially observe further neural treatment effects of reboxetine. 19 healthy males were investigated under reboxetine, amisulpride and placebo for 7 days each within a double-blind cross-over design. During fMRI static erotic picture were presented with preceding anticipation periods. Subjective sexual functions were assessed by a self-reported questionnaire. Neural activations were attenuated within the caudate nucleus, putamen, ventral striatum, the pregenual and anterior midcingulate cortex and in the orbitofrontal cortex under reboxetine. Subjective diminished sexual arousal under reboxetine was correlated with attenuated neural reactivity within the posterior insula. Again, amisulpride left neural activations along with subjective sexual functioning unimpaired. Neither reboxetine nor amisulpride altered differential neural activations during anticipation of erotic stimuli. Our results verified detrimental effects of noradrenergic agents on neural motivational but also emotional and autonomic components of sexual behavior. Considering the overlap of neural network alterations with those evoked by serotonergic agents, our results suggest similar neuromodulatory effects of serotonergic and noradrenergic agents on common neural pathways relevant for sexual behavior. Copyright © 2017 Elsevier B.V. and

  15. Noradrenergic modulation of risk/reward decision making.

    PubMed

    Montes, David R; Stopper, Colin M; Floresco, Stan B

    2015-08-01

    Catecholamine transmission modulates numerous cognitive and reward-related processes that can subserve more complex functions such as cost/benefit decision making. Dopamine has been shown to play an integral role in decisions involving reward uncertainty, yet there is a paucity of research investigating the contributions of noradrenaline (NA) transmission to these functions. The present study was designed to elucidate the contribution of NA to risk/reward decision making in rats, assessed with a probabilistic discounting task. We examined the effects of reducing noradrenergic transmission with the α2 agonist clonidine (10-100 μg/kg), and increasing activity at α2A receptor sites with the agonist guanfacine (0.1-1 mg/kg), the α2 antagonist yohimbine (1-3 mg/kg), and the noradrenaline transporter (NET) inhibitor atomoxetine (0.3-3 mg/kg) on probabilistic discounting. Rats chose between a small/certain reward and a larger/risky reward, wherein the probability of obtaining the larger reward either decreased (100-12.5 %) or increased (12.5-100 %) over a session. In well-trained rats, clonidine reduced risky choice by decreasing reward sensitivity, whereas guanfacine did not affect choice behavior. Yohimbine impaired adjustments in decision biases as reward probability changed within a session by altering negative feedback sensitivity. In a subset of rats that displayed prominent discounting of probabilistic rewards, the lowest dose of atomoxetine increased preference for the large/risky reward when this option had greater long-term utility. These data highlight an important and previously uncharacterized role for noradrenergic transmission in mediating different aspects of risk/reward decision making and mediating reward and negative feedback sensitivity.

  16. Combined Effects of Glucocorticoid and Noradrenergic Activity on Loss Aversion.

    PubMed

    Margittai, Zsofia; Nave, Gideon; Van Wingerden, Marijn; Schnitzler, Alfons; Schwabe, Lars; Kalenscher, Tobias

    2018-01-01

    Loss aversion is a well-known behavioral regularity in financial decision making, describing humans' tendency to overweigh losses compared to gains of the same amount. Recent research indicates that stress and associated hormonal changes affect loss aversion, yet the underlying neuroendocrine mechanisms are still poorly understood. Here, we investigated the causal influence of two major stress neuromodulators, cortisol and noradrenaline, on loss aversion during financial decision making. In a double-blind, placebo-controlled between-subject design, we orally administered either the α2-adrenergic antagonist yohimbine (increasing noradrenergic stimulation), hydrocortisone, both substances, or a placebo to healthy young men. We tested the treatments' influence on a financial decision-making task measuring loss aversion and risk attitude. We found that both drugs combined, relative to either drug by itself, reduced loss aversion in the absence of an effect on risk attitude or choice consistency. Our data suggest that concurrent glucocorticoid and noradrenergic activity prompts an alignment of reward- with loss-sensitivity, and thus diminishes loss aversion. Our results have implications for the understanding of the susceptibility to biases in decision making.

  17. Prenatal Drug Exposures Sensitize Noradrenergic Circuits to Subsequent Disruption by Chlorpyrifos

    PubMed Central

    Slotkin, Theodore A.; Skavicus, Samantha; Seidler, Frederic J.

    2015-01-01

    We examined whether nicotine or dexamethasone, common prenatal drug exposures, sensitize the developing brain to chlorpyrifos. We gave nicotine to pregnant rats throughout gestation at a dose (3 mg/kg/day) producing plasma levels typical of smokers; offspring were then given chlorpyrifos on postnatal days 1–4, at a dose (1 mg/kg) that produces minimally-detectable inhibition of brain cholinesterase activity. In a parallel study, we administered dexamethasone to pregnant rats on gestational days 17–19 at a standard therapeutic dose (0.2 mg/kg) used in the management of preterm labor, followed by postnatal chlorpyrifos. We evaluated cerebellar noradrenergic projections, a known target for each agent, and contrasted the effects with those in the cerebral cortex. Either drug augmented the effect of chlorpyrifos, evidenced by deficits in cerebellar β-adrenergic receptors; the receptor effects were not due to increased systemic toxicity or cholinesterase inhibition, nor to altered chlorpyrifos pharmacokinetics. Further, the deficits were not secondary adaptations to presynaptic hyperinnervation/hyperactivity, as there were significant deficits in presynaptic norepinephrine levels that would serve to augment the functional consequence of receptor deficits. The pretreatments also altered development of cerebrocortical noradrenergic circuits, but with a different overall pattern, reflecting the dissimilar developmental stages of the regions at the time of exposure. However, in each case the net effects represented a change in the developmental trajectory of noradrenergic circuits, rather than simply a continuation of an initial injury. Our results point to the ability of prenatal drug exposure to create a subpopulation with heightened vulnerability to environmental neurotoxicants. PMID:26419632

  18. The noradrenergic component in tapentadol action counteracts μ-opioid receptor-mediated adverse effects on adult neurogenesis.

    PubMed

    Meneghini, Vasco; Cuccurazzu, Bruna; Bortolotto, Valeria; Ramazzotti, Vera; Ubezio, Federica; Tzschentke, Thomas M; Canonico, Pier Luigi; Grilli, Mariagrazia

    2014-05-01

    Opiates were the first drugs shown to negatively impact neurogenesis in the adult mammalian hippocampus. Literature data also suggest that norepinephrine is a positive modulator of hippocampal neurogenesis in vitro and in vivo. On the basis of these observations, we investigated whether tapentadol, a novel central analgesic combining μ-opioid receptor (MOR) agonism with norepinephrine reuptake inhibition (NRI), may produce less inhibition of hippocampal neurogenesis compared with morphine. When tested in vitro, morphine inhibited neuronal differentiation, neurite outgrowth, and survival of adult mouse hippocampal neural progenitors and their progeny, via MOR interaction. By contrast, tapentadol was devoid of these adverse effects on cell survival and reduced neurite outgrowth and the number of newly generated neurons only at nanomolar concentrations where the MOR component is predominant. On the contrary, at higher (micromolar) concentrations, tapentadol elicited proneurogenic and antiapoptotic effects via activation of β2 and α2 adrenergic receptors, respectively. Altogether, these data suggest that the noradrenergic component in tapentadol has the potential to counteract the adverse MOR-mediated effects on hippocampal neurogenesis. As a proof of concept, we showed that reboxetine, an NRI antidepressant, counteracted both antineurogenic and apoptotic effects of morphine in vitro. In line with these observations, chronic tapentadol treatment did not negatively affect hippocampal neurogenesis in vivo. In light of the increasing long-term use of opiates in chronic pain, in principle, the tapentadol combined mechanism of action may result in less or no reduction in adult neurogenesis compared with classic opiates.

  19. Vesicular glutamate transporter DNPI/VGLUT2 is expressed by both C1 adrenergic and nonaminergic presympathetic vasomotor neurons of the rat medulla.

    PubMed

    Stornetta, Ruth L; Sevigny, Charles P; Schreihofer, Ann M; Rosin, Diane L; Guyenet, Patrice G

    2002-03-12

    The main source of excitatory drive to the sympathetic preganglionic neurons that control blood pressure is from neurons located in the rostral ventrolateral medulla (RVLM). This monosynaptic input includes adrenergic (C1), peptidergic, and noncatecholaminergic neurons. Some of the cells in this pathway are suspected to be glutamatergic, but conclusive evidence is lacking. In the present study we sought to determine whether these presympathetic neurons express the vesicular glutamate transporter BNPI/VGLUT1 or the closely related gene DNPI, the rat homolog of the mouse vesicular glutamate transporter VGLUT2. Both BNPI/VGLUT1 and DNPI/VGLUT2 mRNAs were detected in the medulla oblongata by in situ hybridization, but only DNPI/VGLUT2 mRNA was present in the RVLM. Moreover, BNPI immunoreactivity was absent from the thoracic spinal cord lateral horn. DNPI/VGLUT2 mRNA was present in many medullary cells retrogradely labeled with Fluoro-Gold from the spinal cord (T2; four rats). Within the RVLM, 79% of the bulbospinal C1 cells contained DNPI/VGLUT2 mRNA. Bulbospinal noradrenergic A5 neurons did not contain DNPI/VGLUT2 mRNA. The RVLM of six unanesthetized rats subjected to 2 hours of hydralazine-induced hypotension contained tenfold more c-Fos-ir DNPI/VGLUT2 neurons than that of six saline-treated controls. c-Fos-ir DNPI/VGLUT2 neurons included C1 and non-C1 neurons (3:2 ratio). In seven barbiturate-anesthetized rats, 16 vasomotor presympathetic neurons were filled with biotinamide and analyzed for the presence of tyrosine hydroxylase immunoreactivity and/or DNPI/VGLUT2 mRNA. Biotinamide-labeled neurons included C1 and non-C1 cells. Most non-C1 (9/10) and C1 presympathetic cells (5/6) contained DNPI/VGLUT2 mRNA. In conclusion, DNPI/VGLUT2 is expressed by most blood pressure-regulating presympathetic cells of the RVLM. The data suggest that these neurons may be glutamatergic and that the C1 adrenergic phenotype is one of several secondary phenotypes that are differentially

  20. Noradrenaline Triggers GABAA Inhibition of Bed Nucleus of the Stria Terminalis Neurons Projecting to the Ventral Tegmental Area

    PubMed Central

    Dumont, Éric C.; Williams, John T.

    2014-01-01

    The lateral part of the ventral bed nucleus of the stria terminalis (vlBNST) is a critical site for the antiaversive effects of noradrenergic drugs during opioid withdrawal. The objective of the present study is to identify the cellular action(s) of noradrenaline in the vlBNST after withdrawal from a 5 d treatment with morphine. The vlBNST is a heterogeneous cell group with multiple efferent projections. Therefore, neurons projecting to the midbrain were identified by retrograde transport of fluorescent microspheres injected in the ventral tegmental area (VTA). Whole-cell voltage clamp recordings of these neurons and of those sharing physiological properties were done in brain slices. Noradrenaline activated α1-adrenergic receptors to increase GABAA-IPSC frequency. Noradrenaline produced a similar increase in GABAA-IPSCs during acute opioid withdrawal, but this increase resulted from activation of β-adrenergic receptors, adenylyl cyclase, and protein kinase A, as well as α1-adrenergic receptors. Given that neurons in the vlBNST send an excitatory projection to the VTA, noradrenaline may reduce excitatory drive to mesolimbic dopamine cells. This mechanism might contribute to the withdrawal-induced inhibition of dopamine neurons and explain how noradrenergic drugs microinjected into the vlBNST reduce aversive aspects of opioid withdrawal. PMID:15385602

  1. Functional distribution of Ca2+-coupled P2 purinergic receptors among adrenergic and noradrenergic bovine adrenal chromaffin cells.

    PubMed

    Tomé, Angelo R; Castro, Enrique; Santos, Rosa M; Rosário, Luís M

    2007-06-14

    Adrenal chromaffin cells mediate acute responses to stress through the release of epinephrine. Chromaffin cell function is regulated by several receptors, present both in adrenergic (AD) and noradrenergic (NA) cells. Extracellular ATP exerts excitatory and inhibitory actions on chromaffin cells via ionotropic (P2X) and metabotropic (P2Y) receptors. We have taken advantage of the actions of the purinergic agonists ATP and UTP on cytosolic free Ca2+ concentration ([Ca2+]i) to determine whether P2X and P2Y receptors might be asymmetrically distributed among AD and NA chromaffin cells. The [Ca2+]i and the [Na+]i were recorded from immunolabeled bovine chromaffin cells by single-cell fluorescence imaging. Among the ATP-sensitive cells ~40% did not yield [Ca2+]i responses to ATP in the absence of extracellular Ca2+ (Ca2+o), indicating that they expressed P2X receptors and did not express Ca2+- mobilizing P2Y receptors; the remainder expressed Ca2+-mobilizing P2Y receptors. Relative to AD-cells approximately twice as many NA-cells expressed P2X receptors while not expressing Ca2+- mobilizing P2Y receptors, as indicated by the proportion of cells lacking [Ca2+]i responses and exhibiting [Na+]i responses to ATP in the absence and presence of Ca2+o, respectively. The density of P2X receptors in NA-cells appeared to be 30-50% larger, as suggested by comparing the average size of the [Na+]i and [Ca2+]i responses to ATP. Conversely, approximately twice as many AD-cells expressed Ca2+-mobilizing P2Y receptors, and they appeared to exhibit a higher (~20%) receptor density. UTP raised the [Ca2+]i in a fraction of the cells and did not raise the [Na+]i in any of the cells tested, confirming its specificity as a P2Y agonist. The cell density of UTP-sensitive P2Y receptors did not appear to vary among AD- and NA-cells. Although neither of the major purinoceptor types can be ascribed to a particular cell phenotype, P2X and Ca2+-mobilizing P2Y receptors are preferentially located to

  2. Evidence for Fibroblast Growth Factor-2 as a Mediator of Amphetamine-Enhanced Motor Improvement following Stroke

    PubMed Central

    Wolf, William A.; Martin, Jody L.; Kartje, Gwendolyn L.; Farrer, Robert G.

    2014-01-01

    Previously we have shown that addition of amphetamine to physical therapy results in enhanced motor improvement following stroke in rats, which was associated with the formation of new motor pathways from cortical projection neurons of the contralesional cortex. It is unclear what mechanisms are involved, but amphetamine is known to induce the neuronal release of catecholamines as well as upregulate fibroblast growth factor-2 (FGF-2) expression in the brain. Since FGF-2 has been widely documented to stimulate neurite outgrowth, the present studies were undertaken to provide evidence for FGF-2 as a neurobiological mechanism underlying amphetamine-induced neuroplasticity. In the present study rats that received amphetamine plus physical therapy following permanent middle cerebral artery occlusion exhibited significantly greater motor improvement over animals receiving physical therapy alone. Amphetamine plus physical therapy also significantly increased the number of FGF-2 expressing pyramidal neurons of the contralesional cortex at 2 weeks post-stroke and resulted in significant axonal outgrowth from these neurons at 8 weeks post-stroke. Since amphetamine is a known releaser of norepinephrine, in vitro analyses focused on whether noradrenergic stimulation could lead to neurite outgrowth in a manner requiring FGF-2 activity. Primary cortical neurons did not respond to direct stimulation by norepinephrine or amphetamine with increased neurite outgrowth. However, conditioned media from astrocytes exposed to norepinephrine or isoproterenol (a beta adrenergic agonist) significantly increased neurite outgrowth when applied to neuronal cultures. Adrenergic agonists also upregulated FGF-2 expression in astrocytes. Pharmacological analysis indicated that beta receptors and alpha1, but not alpha2, receptors were involved in both effects. Antibody neutralization studies demonstrated that FGF-2 was a critical contributor to neurite outgrowth induced by astrocyte

  3. Prenatal drug exposures sensitize noradrenergic circuits to subsequent disruption by chlorpyrifos.

    PubMed

    Slotkin, Theodore A; Skavicus, Samantha; Seidler, Frederic J

    2015-12-02

    We examined whether nicotine or dexamethasone, common prenatal drug exposures, sensitize the developing brain to chlorpyrifos. We gave nicotine to pregnant rats throughout gestation at a dose (3mg/kg/day) producing plasma levels typical of smokers; offspring were then given chlorpyrifos on postnatal days 1-4, at a dose (1mg/kg) that produces minimally-detectable inhibition of brain cholinesterase activity. In a parallel study, we administered dexamethasone to pregnant rats on gestational days 17-19 at a standard therapeutic dose (0.2mg/kg) used in the management of preterm labor, followed by postnatal chlorpyrifos. We evaluated cerebellar noradrenergic projections, a known target for each agent, and contrasted the effects with those in the cerebral cortex. Either drug augmented the effect of chlorpyrifos, evidenced by deficits in cerebellar β-adrenergic receptors; the receptor effects were not due to increased systemic toxicity or cholinesterase inhibition, nor to altered chlorpyrifos pharmacokinetics. Further, the deficits were not secondary adaptations to presynaptic hyperinnervation/hyperactivity, as there were significant deficits in presynaptic norepinephrine levels that would serve to augment the functional consequence of receptor deficits. The pretreatments also altered development of cerebrocortical noradrenergic circuits, but with a different overall pattern, reflecting the dissimilar developmental stages of the regions at the time of exposure. However, in each case the net effects represented a change in the developmental trajectory of noradrenergic circuits, rather than simply a continuation of an initial injury. Our results point to the ability of prenatal drug exposure to create a subpopulation with heightened vulnerability to environmental neurotoxicants. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  4. Neuroprotective, Neurogenic, and Amyloid Beta Reducing Effect of a Novel Alpha 2-Adrenoblocker, Mesedin, on Astroglia and Neuronal Progenitors upon Hypoxia and Glutamate Exposure

    PubMed Central

    Melkonyan, Magda M.; Hunanyan, Lilit; Lourhmati, Ali; Layer, Nikolas; Beer-Hammer, Sandra; Yenkoyan, Konstantin; Schwab, Matthias; Danielyan, Lusine

    2017-01-01

    Locus coeruleus-noradrenergic system dysfunction is known to contribute to the progression of Alzheimer’s disease (AD). Besides a variety of reports showing the involvement of norepinephrine and its receptor systems in cognition, amyloid β (Aβ) metabolism, neuroinflammation, and neurogenesis, little is known about the contribution of the specific receptors to these actions. Here, we investigated the neurogenic and neuroprotective properties of a new α2 adrenoblocker, mesedin, in astroglial primary cultures (APC) from C57BL/6 and 3×Tg-AD mice. Our results demonstrate that mesedin rescues neuronal precursors and young neurons, and reduces the lactate dehydrogenase (LDH) release from astroglia under hypoxic and normoxic conditions. Mesedin also increased choline acetyltransferase, postsynaptic density marker 95 (PSD95), and Aβ-degrading enzyme neprilysin in the wild type APC, while in the 3×Tg-AD APC exposed to glutamate, it decreased the intracellular content of Aβ and enhanced the survival of synaptophysin-positive astroglia and neurons. These effects in APC can at least partially be attributed to the mesedin’s ability of increasing the expression of Interleukine(IL)-10, which is a potent anti-inflammatory, neuroprotective neurogenic, and Aβ metabolism enhancing factor. In summary, our data identify the neurogenic, neuroprotective, and anti-amyloidogenic action of mesedin in APC. Further in vivo studies are needed to estimate the therapeutic value of mesedin for AD. PMID:29267189

  5. Lesion of the commissural nucleus of the solitary tract/A2 noradrenergic neurons facilitates the activation of angiotensinergic mechanisms in response to hemorrhage.

    PubMed

    Freiria-Oliveira, A H; Blanch, G T; De Paula, P M; Menani, J V; Colombari, D S A

    2013-12-19

    In the present study, we investigated the effects of lesions of A2 neurons of the commissural nucleus of the solitary tract (cNTS) alone or combined with the blockade of angiotensinergic mechanisms on the recovery of arterial pressure (AP) to hemorrhage in conscious rats. Male Holtzman rats (280-320g) received an injection of anti-dopamine-beta-hydroxylase-saporin (12.6ng/60nl; cNTS/A2-lesion, n=28) or immunoglobulin G (IgG)-saporin (12.6ng/60nl, sham, n=24) into the cNTS and 15-21days later had a stainless steel cannula implanted in the lateral ventricle. After 6days, rats were submitted to hemorrhage (four blood withdrawals, 2ml/300g of body weight every 10min). Both cNTS/A2-lesioned and sham rats had similar hypotension to hemorrhage (-62±7 and -73±7mmHg, respectively), however cNTS/A2-lesioned rats rapidly recovered from hypotension (-5±3mmHg at 30min), whereas sham rats did not completely recover until the end of the recording (-20±3mmHg at 60min). Losartan (angiotensin type 1 receptor antagonist) injected intracerebroventricularly (100μg/1μl) or intravenously (i.v.) (10mg/kg of body weight) impaired the recovery of AP in cNTS/A2-lesioned rats (-24±6 and -35±7mmHg at 30min, respectively). In sham rats, only i.v. losartan affected the recovery of AP (-39±6mmHg at 60min). The results suggest that lesion of the A2 neurons in the cNTS facilitates the activation of the angiotensinergic pressor mechanisms in response to hemorrhage. Copyright © 2013 IBRO. Published by Elsevier Ltd. All rights reserved.

  6. Glutamatergic transmission in the nucleus of the solitary tract modulates memory through influences on amygdala noradrenergic systems.

    PubMed

    Miyashita, Teiko; Williams, Cedric L

    2002-02-01

    The authors examined whether glutamate release from the vagus nerve onto the nucleus of the solitary tract (NTS) is one mechanism by which the vagus influences memory and neural activity in limbic structures. Rats trained to drink from a spout were given a footshock (0.35 mA) on Day 5 after approaching the spout. Phosphate-buffered saline or 5.0, 50.0, or 100.0 nmol/0.5 microl glutamate was then infused into the NTS. Glutamate (5.0 or 50.0 nmol) significantly enhanced memory on the retention test. In Experiment 2, this effect was attenuated by blocking noradrenergic receptors in the amygdala with propranolol (0.3 microg/0.5 microl). Experiment 3 used in vivo microdialysis to determine whether footshock plus glutamate (50.0 nmol) alters noradrenergic output in the amygdala. These treatments caused a significant and long-lasting increase in amygdala noradrenergic concentrations. The results indicate that glutamate may be one transmitter that conveys the effects of vagal activation on brain systems that process memory.

  7. Reduced noradrenergic innervation of ventral midbrain dopaminergic cell groups and the subthalamic nucleus in MPTP-treated parkinsonian monkeys.

    PubMed

    Masilamoni, Gunasingh Jeyaraj; Groover, Olivia; Smith, Yoland

    2017-04-01

    There is anatomical and functional evidence that ventral midbrain dopaminergic (DA) cell groups and the subthalamic nucleus (STN) receive noradrenergic innervation in rodents, but much less is known about these interactions in primates. Degeneration of NE neurons in the locus coeruleus (LC) and related brainstem NE cell groups is a well-established pathological feature of Parkinson's disease (PD), but the development of such pathology in animal models of PD has been inconsistent across species and laboratories. We recently demonstrated 30-40% neuronal loss in the LC, A5 and A6 NE cell groups of rhesus monkeys rendered parkinsonian by chronic administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). In this study, we used dopamine-beta-hydroxylase (DβH) immunocytochemistry to assess the impact of this neuronal loss on the number of NE terminal-like varicosities in the substantia nigra pars compacta (SNC), ventral tegmental area (VTA), retrorubral field (RRF) and STN of MPTP-treated parkinsonian monkeys. Our findings reveal that the NE innervation of the ventral midbrain and STN of normal monkeys is heterogeneously distributed being far more extensive in the VTA, RRF and dorsal tier of the SNC than in the ventral SNC and STN. In parkinsonian monkeys, all regions underwent a significant (~50-70%) decrease in NE innervation. At the electron microscopic level, some DβH-positive terminals formed asymmetric axo-dendritic synapses in VTA and STN. These findings demonstrate that the VTA, RRF and SNCd are the main ventral midbrain targets of ascending NE inputs, and that these connections undergo a major break-down in chronically MPTP-treated parkinsonian monkeys. This severe degeneration of the ascending NE system may contribute to the pathophysiology of ventral midbrain and STN neurons in PD. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. Noradrenergic innervation of the rat spinal cord caudal to a complete spinal cord transection: effects of olfactory ensheathing glia.

    PubMed

    Takeoka, Aya; Kubasak, Marc D; Zhong, Hui; Kaplan, Jennifer; Roy, Roland R; Phelps, Patricia E

    2010-03-01

    Transplantation of olfactory bulb-derived olfactory ensheathing glia (OEG) combined with step training improves hindlimb locomotion in adult rats with a complete spinal cord transection. Spinal cord injury studies use the presence of noradrenergic (NA) axons caudal to the injury site as evidence of axonal regeneration and we previously found more NA axons just caudal to the transection in OEG- than media-injected spinal rats. We therefore hypothesized that OEG transplantation promotes descending coeruleospinal regeneration that contributes to the recovery of hindlimb locomotion. Now we report that NA axons are present throughout the caudal stump of both media- and OEG-injected spinal rats and they enter the spinal cord from the periphery via dorsal and ventral roots and along large penetrating blood vessels. These results indicate that the presence of NA fibers in the caudal spinal cord is not a reliable indicator of coeruleospinal regeneration. We then asked if NA axons appose cholinergic neurons associated with motor functions, i.e., central canal cluster and partition cells (active during fictive locomotion) and somatic motor neurons (SMNs). We found more NA varicosities adjacent to central canal cluster cells, partition cells, and SMNs in the lumbar enlargement of OEG- than media-injected rats. As non-synaptic release of NA is common in the spinal cord, more associations between NA varicosities and motor-associated cholinergic neurons in the lumbar spinal cord may contribute to the improved treadmill stepping observed in OEG-injected spinal rats. This effect could be mediated through direct association with SMNs and/or indirectly via cholinergic interneurons. Copyright 2009 Elsevier Inc. All rights reserved.

  9. NORADRENERGIC INNERVATION OF THE RAT SPINAL CORD CAUDAL TO A COMPLETE SPINAL CORD TRANSECTION: EFFECTS OF OLFACTORY ENSHEATHING GLIA

    PubMed Central

    Takeoka, Aya; Kubasak, Marc D.; Zhong, Hui; Kaplan, Jennifer; Roy, Roland R.; Phelps, Patricia E.

    2010-01-01

    Transplantation of olfactory bulb-derived olfactory ensheathing glia (OEG) combined with step training improves hindlimb locomotion in adult rats with a complete spinal cord transection. Spinal cord injury studies use the presence of noradrenergic (NA) axons caudal to the injury site as evidence of axonal regeneration and we previously found more NA axons just caudal to the transection in OEG- than media-injected spinal rats. We therefore hypothesized that OEG transplantation promotes descending coeruleospinal regeneration that contributes to the recovery of hindlimb locomotion. Now we report that NA axons are present throughout the caudal stump of both media- and OEG-injected spinal rats and they enter the spinal cord from the periphery via dorsal and ventral roots and along large penetrating blood vessels. These results indicate that the presence of NA fibers in the caudal spinal cord is not a reliable indicator of coeruleospinal regeneration. We then asked if NA axons appose cholinergic neurons associated with motor functions, i.e., central canal cluster and partition cells (active during fictive locomotion) and somatic motor neurons (SMNs). We found more NA varicosities adjacent to central canal cluster cells, partition cells, and SMNs in the lumbar enlargement of OEG- than media-injected rats. As non-synaptic release of NA is common in the spinal cord, more associations between NA varicosities and motor-associated cholinergic neurons in the lumbar spinal cord may contribute to the improved treadmill stepping observed in OEG-injected spinal rats. This effect could be mediated through direct association with SMNs and/or indirectly via cholinergic interneurons. PMID:20025875

  10. Damage to Arousal-Promoting Brainstem Neurons with Traumatic Brain Injury.

    PubMed

    Valko, Philipp O; Gavrilov, Yuri V; Yamamoto, Mihoko; Noaín, Daniela; Reddy, Hasini; Haybaeck, Johannes; Weis, Serge; Baumann, Christian R; Scammell, Thomas E

    2016-06-01

    Coma and chronic sleepiness are common after traumatic brain injury (TBI). Here, we explored whether injury to arousal-promoting brainstem neurons occurs in patients with fatal TBI. Postmortem examination of 8 TBI patients and 10 controls. Compared to controls, TBI patients had 17% fewer serotonergic neurons in the dorsal raphe nucleus (effect size: 1.25), but the number of serotonergic neurons did not differ in the median raphe nucleus. TBI patients also had 29% fewer noradrenergic neurons in the locus coeruleus (effect size: 0.96). The number of cholinergic neurons in the pedunculopontine and laterodorsal tegmental nuclei (PPT/LDT) was similar in TBI patients and controls. TBI injures arousal-promoting neurons of the mesopontine tegmentum, but this injury is less severe than previously observed in hypothalamic arousal-promoting neurons. Most likely, posttraumatic arousal disturbances are not primarily caused by damage to these brainstem neurons, but arise from an aggregate of injuries, including damage to hypothalamic arousal nuclei and disruption of other arousal-related circuitries. © 2016 Associated Professional Sleep Societies, LLC.

  11. Differential effects of unilateral olfactory deprivation on noradrenergic and cholinergic systems in the main olfactory bulb of the rat.

    PubMed

    Gómez, C; Briñón, J G; Colado, M I; Orio, L; Vidal, M; Barbado, M V; Alonso, J R

    2006-09-15

    The lack of environmental olfactory stimulation produced by sensory deprivation causes significant changes in the deprived olfactory bulb. Olfactory transmission in the main olfactory bulb (MOB) is strongly modulated by centrifugal systems. The present report examines the effects of unilateral deprivation on the noradrenergic and cholinergic centrifugal systems innervating the MOB. The morphology, distribution, and density of positive axons were studied in the MOBs of control and deprived rats, using dopamine-beta-hydroxylase (DBH)-immunohistochemistry and acetylcholinesterase (AChE) histochemistry in serial sections. Catecholamine content was compared among the different groups of MOBs (control, contralateral, and ipsilateral to the deprivation) using high-performance liquid chromatography analysis. Sensory deprivation revealed that the noradrenergic system developed adaptive plastic changes after olfactory deprivation, including important modifications in its fiber density and distribution, while no differences in cholinergic innervation were observed under the same conditions. The noradrenergic system underwent an important alteration in the glomerular layer, in which some glomeruli showed a dense noradrenergic innervation that was not detected in control animals. The DBH-positive glomeruli with the highest noradrenergic fiber density were compared with AChE-stained sections and it was observed that the strongly noradrenergic-innervated glomeruli were always atypical glomeruli (characterized by their strong degree of cholinergic innervation). In addition to the morphological findings, our biochemical data revealed that olfactory deprivation caused a decrease in the content of dopamine and its metabolite 3,4-dihydroxyphenylacetic acid in the ipsilateral MOB in comparison to the contralateral and control MOBs, together with an increase in noradrenaline levels in both the ipsilateral and contralateral MOBs. Our results show that regulation of the noradrenergic

  12. Central noradrenergic mechanisms and the acute stress response during painful stimulation.

    PubMed

    Chapman, C Richard; Bradshaw, David H; Donaldson, Gary W; Jacobson, Robert C; Nakamura, Yoshio

    2014-12-01

    Events that threaten tissue integrity including noxious stimulation activate central noradrenergic circuits, particularly locus coeruleus and its projections. Recent advances in theory hold that an adaptive, defensive shift in brain activity takes place in response to threat. In principle, this shift may accentuate the autonomic and central biomarkers of the perception of painful events and the experience of pain itself. We have examined the effects of an alpha-2 agonist on pupil dilation responses, skin conductance responses, near field somatosensory evoked potentials and pain reports in normal volunteers undergoing repeated trials of painful fingertip stimulation delivered at low, medium and high intensities. In a double-blinded study, 114 healthy male and female volunteers underwent repeated noxious stimulation under baseline, placebo and active drug conditions where the active drug was the alpha-2 agonist tizanidine 4 mg. In contrast to baseline and placebo conditions, tizanidine 4 mg significantly reduced the magnitudes of the mean pupil dilation response, the mean skin conductance response, the mean near field somatosensory evoked potential peak-to-peak amplitude and the mean pain intensity rating. Stimulus intensity significantly altered all three biomarkers and the pain report in a graded fashion. There were no sex differences. These findings support the hypotheses that painful events activate central noradrenergic circuits, and that these circuits play a role in the autonomic and central arousal associated with pain. © The Author(s) 2014.

  13. Neuropeptide S interacts with the basolateral amygdala noradrenergic system in facilitating object recognition memory consolidation.

    PubMed

    Han, Ren-Wen; Xu, Hong-Jiao; Zhang, Rui-San; Wang, Pei; Chang, Min; Peng, Ya-Li; Deng, Ke-Yu; Wang, Rui

    2014-01-01

    The noradrenergic activity in the basolateral amygdala (BLA) was reported to be involved in the regulation of object recognition memory. As the BLA expresses high density of receptors for Neuropeptide S (NPS), we investigated whether the BLA is involved in mediating NPS's effects on object recognition memory consolidation and whether such effects require noradrenergic activity. Intracerebroventricular infusion of NPS (1nmol) post training facilitated 24-h memory in a mouse novel object recognition task. The memory-enhancing effect of NPS could be blocked by the β-adrenoceptor antagonist propranolol. Furthermore, post-training intra-BLA infusions of NPS (0.5nmol/side) improved 24-h memory for objects, which was impaired by co-administration of propranolol (0.5μg/side). Taken together, these results indicate that NPS interacts with the BLA noradrenergic system in improving object recognition memory during consolidation. Copyright © 2013 Elsevier Inc. All rights reserved.

  14. Caudal fourth ventricular administration of the AMPK activator 5-aminoimidazole-4-carboxamide-riboside regulates glucose and counterregulatory hormone profiles, dorsal vagal complex metabolosensory neuron function, and hypothalamic Fos expression.

    PubMed

    Ibrahim, Baher A; Tamrakar, Pratistha; Gujar, Amit D; Cherian, Ajeesh Koshy; Briski, Karen P

    2013-09-01

    This study investigated the hypothesis that estrogen controls hindbrain AMP-activated protein kinase (AMPK) activity and regulation of blood glucose, counterregulatory hormone secretion, and hypothalamic nerve cell transcriptional status. Dorsal vagal complex A2 noradrenergic neurons were laser microdissected from estradiol benzoate (E)- or oil (O)-implanted ovariectomized female rats after caudal fourth ventricular (CV4) delivery of the AMPK activator 5-aminoimidazole-4-carboxamide-riboside (AICAR), for Western blot analysis. E advanced AICAR-induced increases in A2 phospho-AMPK (pAMPK) expression and in blood glucose levels and was required for augmentation of Fos, estrogen receptor-α (ERα), monocarboxylate transporter-2, and glucose transporter-3 protein in A2 neurons and enhancement of corticosterone secretion by this treatment paradigm. CV4 AICAR also resulted in site-specific modifications in Fos immunolabeling of hypothalamic metabolic structures, including the paraventricular, ventromedial, and arcuate nuclei. The current studies demonstrate that estrogen regulates AMPK activation in caudal hindbrain A2 noradrenergic neurons during pharmacological replication of energy shortage in this area of the brain, and that this sensor is involved in neural regulation of glucostasis, in part, through control of corticosterone secretion. The data provide unique evidence that A2 neurons express both ERα and -β proteins and that AMPK upregulates cellular sensitivity to ERα-mediated signaling during simulated energy insufficiency. The results also imply that estrogen promotes glucose and lactate uptake by these cells under those conditions. Evidence for correlation between hindbrain AMPK and hypothalamic nerve cell genomic activation provides novel proof for functional connectivity between this hindbrain sensor and higher order metabolic brain loci while demonstrating a modulatory role for estrogen in this interaction. Copyright © 2013 Wiley Periodicals, Inc.

  15. Cholinergic, But Not Dopaminergic or Noradrenergic, Enhancement Sharpens Visual Spatial Perception in Humans

    PubMed Central

    Wallace, Deanna L.

    2017-01-01

    The neuromodulator acetylcholine modulates spatial integration in visual cortex by altering the balance of inputs that generate neuronal receptive fields. These cholinergic effects may provide a neurobiological mechanism underlying the modulation of visual representations by visual spatial attention. However, the consequences of cholinergic enhancement on visuospatial perception in humans are unknown. We conducted two experiments to test whether enhancing cholinergic signaling selectively alters perceptual measures of visuospatial interactions in human subjects. In Experiment 1, a double-blind placebo-controlled pharmacology study, we measured how flanking distractors influenced detection of a small contrast decrement of a peripheral target, as a function of target-flanker distance. We found that cholinergic enhancement with the cholinesterase inhibitor donepezil improved target detection, and modeling suggested that this was mainly due to a narrowing of the extent of facilitatory perceptual spatial interactions. In Experiment 2, we tested whether these effects were selective to the cholinergic system or would also be observed following enhancements of related neuromodulators dopamine or norepinephrine. Unlike cholinergic enhancement, dopamine (bromocriptine) and norepinephrine (guanfacine) manipulations did not improve performance or systematically alter the spatial profile of perceptual interactions between targets and distractors. These findings reveal mechanisms by which cholinergic signaling influences visual spatial interactions in perception and improves processing of a visual target among distractors, effects that are notably similar to those of spatial selective attention. SIGNIFICANCE STATEMENT Acetylcholine influences how visual cortical neurons integrate signals across space, perhaps providing a neurobiological mechanism for the effects of visual selective attention. However, the influence of cholinergic enhancement on visuospatial perception remains

  16. Noradrenergic Control of Odor Recognition in a Nonassociative Olfactory Learning Task in the Mouse

    ERIC Educational Resources Information Center

    Veyrac, Alexandra; Nguyen, Veronique; Marien, Marc; Didier, Anne; Jourdan, Francois

    2007-01-01

    The present study examined the influence of pharmacological modulations of the locus coeruleus noradrenergic system on odor recognition in the mouse. Mice exposed to a nonrewarded olfactory stimulation (training) were able to memorize this odor and to discriminate it from a new odor in a recall test performed 15 min later. At longer delays (30 or…

  17. Chronic Desipramine Treatment Rescues Depression-Related, Social and Cognitive Deficits in Engrailed-2 Knockout Mice

    PubMed Central

    Brielmaier, Jennifer; Senerth, Julia M.; Silverman, Jill L.; Matteson, Paul G.; Millonig, James H.; DiCicco-Bloom, Emanuel; Crawley, Jacqueline N.

    2014-01-01

    Engrailed-2 (En2) is a homeobox transcription factor that regulates neurodevelopmental processes including neuronal connectivity and elaboration of monoaminergic neurons in the ventral hindbrain. We previously reported abnormalities in brain noradrenergic concentrations in En2 null mutant mice that were accompanied by increased immobility in the forced swim test, relevant to depression. An EN2 genetic polymorphism has been associated with autism spectrum disorders (ASD), and mice with a deletion in En2 display social abnormalities and cognitive deficits that may be relevant to multiple neuropsychiatric conditions. The present study evaluated the ability of chronic treatment with desipramine (DMI), a selective norepinephrine reuptake inhibitor and classical antidepressant, to reverse behavioral abnormalities in En2 −/− mice. DMI treatment significantly reduced immobility in the tail suspension and forced swim tests, restored sociability in the three-chambered social approach task, and reversed impairments in contextual fear conditioning in En2 −/− mice. Our findings indicate that modulation of brain noradrenergic systems rescues the depression-related phenotype in En2 −/− mice and suggest new roles for norepinephrine in the pathophysiology of the social and cognitive deficits seen in neuropsychiatric disorders such as autism or schizophrenia. PMID:24730055

  18. Damage to Arousal-Promoting Brainstem Neurons with Traumatic Brain Injury

    PubMed Central

    Valko, Philipp O.; Gavrilov, Yuri V.; Yamamoto, Mihoko; Noaín, Daniela; Reddy, Hasini; Haybaeck, Johannes; Weis, Serge; Baumann, Christian R.; Scammell, Thomas E.

    2016-01-01

    Study Objectives: Coma and chronic sleepiness are common after traumatic brain injury (TBI). Here, we explored whether injury to arousal-promoting brainstem neurons occurs in patients with fatal TBI. Methods: Postmortem examination of 8 TBI patients and 10 controls. Results: Compared to controls, TBI patients had 17% fewer serotonergic neurons in the dorsal raphe nucleus (effect size: 1.25), but the number of serotonergic neurons did not differ in the median raphe nucleus. TBI patients also had 29% fewer noradrenergic neurons in the locus coeruleus (effect size: 0.96). The number of cholinergic neurons in the pedunculopontine and laterodorsal tegmental nuclei (PPT/LDT) was similar in TBI patients and controls. Conclusions: TBI injures arousal-promoting neurons of the mesopontine tegmentum, but this injury is less severe than previously observed in hypothalamic arousal-promoting neurons. Most likely, posttraumatic arousal disturbances are not primarily caused by damage to these brainstem neurons, but arise from an aggregate of injuries, including damage to hypothalamic arousal nuclei and disruption of other arousal-related circuitries. Citation: Valko PO, Gavrilov YV, Yamamoto M, Noain D, Reddy H, Haybaeck J, Weis S, Baumann CR, Scammell TE. Damage to arousal-promoting brainstem neurons with traumatic brain injury. SLEEP 2016;39(6):1249–1252. PMID:27091531

  19. Noradrenergic blockade stabilizes prefrontal activity and enables fear extinction under stress

    PubMed Central

    Fitzgerald, Paul J.; Giustino, Thomas F.; Seemann, Jocelyn R.; Maren, Stephen

    2015-01-01

    Stress-induced impairments in extinction learning are believed to sustain posttraumatic stress disorder (PTSD). Noradrenergic signaling may contribute to extinction impairments by modulating medial prefrontal cortex (mPFC) circuits involved in fear regulation. Here we demonstrate that aversive fear conditioning rapidly and persistently alters spontaneous single-unit activity in the prelimbic and infralimbic subdivisions of the mPFC in behaving rats. These conditioning-induced changes in mPFC firing were mitigated by systemic administration of propranolol (10 mg/kg, i.p.), a β-noradrenergic receptor antagonist. Moreover, propranolol administration dampened the stress-induced impairment in extinction observed when extinction training is delivered shortly after fear conditioning. These findings suggest that β-adrenoceptors mediate stress-induced changes in mPFC spike firing that contribute to extinction impairments. Propranolol may be a helpful adjunct to behavioral therapy for PTSD, particularly in patients who have recently experienced trauma. PMID:26124100

  20. Activation of β-noradrenergic receptors enhances rhythmic bursting in mouse olfactory bulb external tufted cells.

    PubMed

    Zhou, Fu-Wen; Dong, Hong-Wei; Ennis, Matthew

    2016-12-01

    The main olfactory bulb (MOB) receives a rich noradrenergic innervation from the nucleus locus coeruleus. Despite the well-documented role of norepinephrine and β-adrenergic receptors in neonatal odor preference learning, identified cellular physiological actions of β-receptors in the MOB have remained elusive. β-Receptors are expressed at relatively high levels in the MOB glomeruli, the location of external tufted (ET) cells that exert an excitatory drive on mitral and other cell types. The present study investigated the effects of β-receptor activation on the excitability of ET cells with patch-clamp electrophysiology in mature mouse MOB slices. Isoproterenol and selective β 2 -, but not β 1 -, receptor agonists were found to enhance two key intrinsic currents involved in ET burst initiation: persistent sodium (I NaP ) and hyperpolarization-activated inward (I h ) currents. Together, the positive modulation of these currents increased the frequency and strength of ET cell rhythmic bursting. Rodent sniff frequency and locus coeruleus neuronal firing increase in response to novel stimuli or environments. The increase in ET excitability by β-receptor activation may better enable ET cell rhythmic bursting, and hence glomerular network activity, to pace faster sniff rates during heightened norepinephrine release associated with arousal. Copyright © 2016 the American Physiological Society.

  1. The Memory Function of Noradrenergic Activity in Non-REM Sleep

    ERIC Educational Resources Information Center

    Gais, Steffen; Rasch, Bjorn; Dahmen, Johannes C.; Sara, Susan; Born, Jan

    2011-01-01

    There is a long-standing assumption that low noradrenergic activity during sleep reflects mainly the low arousal during this brain state. Nevertheless, recent research has demonstrated that the locus coeruleus, which is the main source of cortical noradrenaline, displays discrete periods of intense firing during non-REM sleep, without any signs of…

  2. Electrophysiological characterization of neurons in the dorsolateral pontine REM sleep induction zone of the rat: intrinsic membrane properties and responses to carbachol and orexins

    PubMed Central

    Brown§, Ritchie E.; Winston, Stuart; Basheer, Radhika; Thakkar, Mahesh M; McCarley, Robert W.

    2006-01-01

    Pharmacological, lesion and single-unit recording techniques in several animal species have identified a region of the pontine reticular formation (Subcoeruleus, SubC) just ventral to the locus coeruleus as critically involved in the generation of rapid-eye-movement (REM) sleep. However, the intrinsic membrane properties and responses of SubC neurons to neurotransmitters important in REM sleep control, such as acetylcholine and orexins/hypocretins, have not previously been examined in any animal species and thus were targeted in this study. We obtained whole-cell patch-clamp recordings from visually identified SubC neurons in rat brain slices in vitro. Two groups of large neurons (mean diameter 30 and 27μm) were tentatively identified as cholinergic (rostral SubC) and noradrenergic (caudal SubC) neurons. SubC reticular neurons (non-cholinergic, non-noradrenergic) showed a medium-sized depolarizing sag during hyperpolarizing current pulses and often had a rebound depolarization (low-threshold spike, LTS). During depolarizing current pulses they exhibited little adaptation and fired maximally at 30–90 Hz. Those SubC reticular neurons excited by carbachol (n=27) fired spontaneously at 6 Hz, often exhibited a moderately sized LTS, and varied widely in size (17–42 μm). Carbachol-inhibited SubC reticular neurons were medium-sized (15–25 μm) and constituted two groups. The larger group (n=22) was silent at rest and possessed a prominent LTS and associated 1–4 action potentials. The second, smaller group (n=8) had a delayed return to baseline at the offset of hyperpolarizing pulses. Orexins excited both carbachol excited and carbachol inhibited SubC reticular neurons. SubC reticular neurons had intrinsic membrane properties and responses to carbachol similar to those described for other reticular neurons but a larger number of carbachol inhibited neurons were found (> 50 %), the majority of which demonstrated a prominent LTS and may correspond to PGO-on neurons

  3. Nrf2 promotes neuronal cell differentiation.

    PubMed

    Zhao, Fei; Wu, Tongde; Lau, Alexandria; Jiang, Tao; Huang, Zheping; Wang, Xiao-Jun; Chen, Weimin; Wong, Pak Kin; Zhang, Donna D

    2009-09-15

    The transcription factor Nrf2 has emerged as a master regulator of the endogenous antioxidant response, which is critical in defending cells against environmental insults and in maintaining intracellular redox balance. However, whether Nrf2 has any role in neuronal cell differentiation is largely unknown. In this report, we have examined the effects of Nrf2 on cell differentiation using a neuroblastoma cell line, SH-SY5Y. Retinoic acid (RA) and 12-O-tetradecanoylphorbol 13-acetate, two well-studied inducers of neuronal differentiation, are able to induce Nrf2 and its target gene NAD(P)H quinone oxidoreductase 1 in a dose- and time-dependent manner. RA-induced Nrf2 up-regulation is accompanied by neurite outgrowth and an induction of two neuronal differentiation markers, neurofilament-M and microtubule-associated protein 2. Overexpression of Nrf2 in SH-SY5Y cells promotes neuronal differentiation, whereas inhibition of endogenous Nrf2 expression inhibited neuronal differentiation. More remarkably, the positive role of Nrf2 in neuronal differentiation was verified ex vivo in primary neuron culture. Primary neurons isolated from Nrf2-null mice showed a retarded progress in differentiation, compared to those from wild-type mice. Collectively, our data demonstrate a novel role for Nrf2 in promoting neuronal cell differentiation, which will open new perspectives for therapeutic uses of Nrf2 activators in patients with neurodegenerative diseases.

  4. The PDAPP mouse model of Alzheimer's disease: locus coeruleus neuronal shrinkage.

    PubMed

    German, Dwight C; Nelson, Omar; Liang, Fen; Liang, Chang-Lin; Games, Dora

    2005-11-28

    Alzheimer's disease is characterized by neuronal degeneration in the cerebral cortex and hippocampus and subcortical neuronal degeneration in such nuclei as the locus coeruleus (LC). Transgenic mice overexpressing mutant human amyloid precursor protein V717F, PDAPP mice, develop several Alzheimer's disease-like lesions. The present study sought to determine whether there is also loss of LC noradrenergic neurons or evidence of degenerative changes in these animals. PDAPP hemizygous and wild-type littermate control mice were examined at 23 months of age, at a time when there are numerous amyloid-beta (Abeta) plaques in the neocortex and hippocampus. Tissue sections were stained immunohistochemically with an antibody against tyrosine hydroxylase (TH) to identify LC neurons. Computer imaging procedures were used to count the TH-immunoreactive somata in sections through the rostral-caudal extent of the nucleus. There was no loss of LC neurons in the hemizygous mice. In a second experiment, homozygous PDAPP and wild-type mice were examined, at 2 months and 24 months of age. Again there was no age-related loss of neurons in the homozygous animals. In the portion of the LC where neurons reside that project to the cortex and hippocampus, however, the neurons were decreased in size selectively in the 24-month-old transgenic animals. These data indicate that overt LC cell loss does not occur following abundant overexpression of Abeta peptide. However, the selective size reduction of the LC neuronal population projecting to cortical and hippocampal regions containing Abeta-related neuropathology implies that these cells may be subjected to a retrograde-mediated stress. Copyright 2005 Wiley-Liss, Inc.

  5. A computational psychiatry approach identifies how alpha-2A noradrenergic agonist Guanfacine affects feature-based reinforcement learning in the macaque

    PubMed Central

    Hassani, S. A.; Oemisch, M.; Balcarras, M.; Westendorff, S.; Ardid, S.; van der Meer, M. A.; Tiesinga, P.; Womelsdorf, T.

    2017-01-01

    Noradrenaline is believed to support cognitive flexibility through the alpha 2A noradrenergic receptor (a2A-NAR) acting in prefrontal cortex. Enhanced flexibility has been inferred from improved working memory with the a2A-NA agonist Guanfacine. But it has been unclear whether Guanfacine improves specific attention and learning mechanisms beyond working memory, and whether the drug effects can be formalized computationally to allow single subject predictions. We tested and confirmed these suggestions in a case study with a healthy nonhuman primate performing a feature-based reversal learning task evaluating performance using Bayesian and Reinforcement learning models. In an initial dose-testing phase we found a Guanfacine dose that increased performance accuracy, decreased distractibility and improved learning. In a second experimental phase using only that dose we examined the faster feature-based reversal learning with Guanfacine with single-subject computational modeling. Parameter estimation suggested that improved learning is not accounted for by varying a single reinforcement learning mechanism, but by changing the set of parameter values to higher learning rates and stronger suppression of non-chosen over chosen feature information. These findings provide an important starting point for developing nonhuman primate models to discern the synaptic mechanisms of attention and learning functions within the context of a computational neuropsychiatry framework. PMID:28091572

  6. Endoplasmic reticulum stress in wake-active neurons progresses with aging.

    PubMed

    Naidoo, Nirinjini; Zhu, Jingxu; Zhu, Yan; Fenik, Polina; Lian, Jie; Galante, Ray; Veasey, Sigrid

    2011-08-01

    Fragmentation of wakefulness and sleep are expected outcomes of advanced aging. We hypothesize that wake neurons develop endoplasmic reticulum dyshomeostasis with aging, in parallel with impaired wakefulness. In this series of experiments, we sought to more fully characterize age-related changes in wakefulness and then, in relevant wake neuronal populations, explore functionality and endoplasmic reticulum homeostasis. We report that old mice show greater sleep/wake transitions in the active period with markedly shortened wake periods, shortened latencies to sleep, and less wake time in the subjective day in response to a novel social encounter. Consistent with sleep/wake instability and reduced social encounter wakefulness, orexinergic and noradrenergic wake neurons in aged mice show reduced c-fos response to wakefulness and endoplasmic reticulum dyshomeostasis with increased nuclear translocation of CHOP and GADD34. We have identified an age-related unfolded protein response injury to and dysfunction of wake neurons. It is anticipated that these changes contribute to sleep/wake fragmentation and cognitive impairment in aging. © 2011 The Authors. Aging Cell © 2011 Blackwell Publishing Ltd/Anatomical Society of Great Britain and Ireland.

  7. Anti-dopamine beta-hydroxylase immunotoxin-induced sympathectomy in adult rats

    NASA Technical Reports Server (NTRS)

    Picklo, M. J.; Wiley, R. G.; Lonce, S.; Lappi, D. A.; Robertson, D.

    1995-01-01

    Anti-dopamine beta-hydroxylase immunotoxin (DHIT) is an antibody-targeted noradrenergic lesioning tool comprised of a monoclonal antibody against the noradrenergic enzyme, dopamine beta-hydroxylase, conjugated to saporin, a ribosome-inactivating protein. Noradrenergic-neuron specificity and completeness and functionality of sympathectomy were assessed. Adult, male Sprague-Dawley rats were given 28.5, 85.7, 142 or 285 micrograms/kg DHIT i.v. Three days after injection, a 6% to 73% decrease in the neurons was found in the superior cervical ganglia of the animals. No loss of sensory, nodose and dorsal root ganglia, neurons was observed at the highest dose of DHIT. In contrast, the immunotoxin, 192-saporin (142 micrograms/kg), lesioned all three ganglia. To assess the sympathectomy, 2 wk after treatment (285 micrograms/kg), rats were anesthetized with urethane (1 g/kg) and cannulated in the femoral artery and vein. DHIT-treated animals' basal systolic blood pressure and heart rate were significantly lower than controls. Basal plasma norepinephrine levels were 41% lower in DHIT-treated animals than controls. Tyramine-stimulated release of norepinephrine in DHIT-treated rats was 27% of controls. Plasma epinephrine levels of DHIT animals were not reduced. DHIT-treated animals exhibited a 2-fold hypersensitivity to the alpha-adrenergic agonist phenylephrine. We conclude that DHIT selectively delivered saporin to noradrenergic neurons resulting in destruction of these neurons. Anti-dopamine beta-hydroxylase immunotoxin administration produces a rapid, irreversible sympathectomy.

  8. C1 neurons: the body's EMTs

    PubMed Central

    Stornetta, Ruth L.; Bochorishvili, Genrieta; DePuy, Seth D.; Burke, Peter G. R.; Abbott, Stephen B. G.

    2013-01-01

    The C1 neurons reside in the rostral and intermediate portions of the ventrolateral medulla (RVLM, IVLM). They use glutamate as a fast transmitter and synthesize catecholamines plus various neuropeptides. These neurons regulate the hypothalamic pituitary axis via direct projections to the paraventricular nucleus and regulate the autonomic nervous system via projections to sympathetic and parasympathetic preganglionic neurons. The presympathetic C1 cells, located in the RVLM, are probably organized in a roughly viscerotopic manner and most of them regulate the circulation. C1 cells are variously activated by hypoglycemia, infection or inflammation, hypoxia, nociception, and hypotension and contribute to most glucoprivic responses. C1 cells also stimulate breathing and activate brain stem noradrenergic neurons including the locus coeruleus. Based on the various effects attributed to the C1 cells, their axonal projections and what is currently known of their synaptic inputs, subsets of C1 cells appear to be differentially recruited by pain, hypoxia, infection/inflammation, hemorrhage, and hypoglycemia to produce a repertoire of stereotyped autonomic, metabolic, and neuroendocrine responses that help the organism survive physical injury and its associated cohort of acute infection, hypoxia, hypotension, and blood loss. C1 cells may also contribute to glucose and cardiovascular homeostasis in the absence of such physical stresses, and C1 cell hyperactivity may contribute to the increase in sympathetic nerve activity associated with diseases such as hypertension. PMID:23697799

  9. C1 neurons: the body's EMTs.

    PubMed

    Guyenet, Patrice G; Stornetta, Ruth L; Bochorishvili, Genrieta; Depuy, Seth D; Burke, Peter G R; Abbott, Stephen B G

    2013-08-01

    The C1 neurons reside in the rostral and intermediate portions of the ventrolateral medulla (RVLM, IVLM). They use glutamate as a fast transmitter and synthesize catecholamines plus various neuropeptides. These neurons regulate the hypothalamic pituitary axis via direct projections to the paraventricular nucleus and regulate the autonomic nervous system via projections to sympathetic and parasympathetic preganglionic neurons. The presympathetic C1 cells, located in the RVLM, are probably organized in a roughly viscerotopic manner and most of them regulate the circulation. C1 cells are variously activated by hypoglycemia, infection or inflammation, hypoxia, nociception, and hypotension and contribute to most glucoprivic responses. C1 cells also stimulate breathing and activate brain stem noradrenergic neurons including the locus coeruleus. Based on the various effects attributed to the C1 cells, their axonal projections and what is currently known of their synaptic inputs, subsets of C1 cells appear to be differentially recruited by pain, hypoxia, infection/inflammation, hemorrhage, and hypoglycemia to produce a repertoire of stereotyped autonomic, metabolic, and neuroendocrine responses that help the organism survive physical injury and its associated cohort of acute infection, hypoxia, hypotension, and blood loss. C1 cells may also contribute to glucose and cardiovascular homeostasis in the absence of such physical stresses, and C1 cell hyperactivity may contribute to the increase in sympathetic nerve activity associated with diseases such as hypertension.

  10. Interaction of brain noradrenergic system and the hypothalamic-pituitary-adrenal (HPA) axis in man.

    PubMed

    Young, Elizabeth A; Abelson, James L; Cameron, Oliver G

    2005-09-01

    Numerous interactions between the brainstem locus coeruleus system and the HPA axis have been shown in experimental animals. This relationship is less well characterized in humans and little is known about the influence of psychiatric disorders, which disturb one of these systems, on this relationship. Untreated subjects with pure MDD (n = 13), MDD with comorbid anxiety disorders (n = 17), and pure anxiety disorders (n = 15) were recruited by advertising. Age and sex matched control subjects were recruited for each subject with a psychiatric diagnosis (n = 45). All subjects underwent a social stressor, the Trier Social Stress Test (TSST), and blood was collected for ACTH assay. These same subjects also underwent a clonidine challenge study for assessment of growth hormone release as a marker of tonic noradrenergic activation. Examining log transformed area under the curve response for each hormone, a significant negative relationship (simple regression) was observed between systems in normal subjects. This relationship was preserved in anxiety subjects. However, both pure depressed and comorbid depressed and anxiety subjects demonstrated disruption of this relationship. Under normal circumstances, noradrenergic systems can influence the magnitude of the HPA axis response to stress. However, in subjects with major depression, HPA axis activation appears autonomous of noradrenergic influence.

  11. Monoamine neurons in the human brain stem: anatomy, magnetic resonance imaging findings, and clinical implications.

    PubMed

    Sasaki, Makoto; Shibata, Eri; Tohyama, Koujiro; Kudo, Kohsuke; Endoh, Jin; Otsuka, Kotaro; Sakai, Akio

    2008-11-19

    By using high-resolution, conventional, and neuromelanin-sensitive magnetic resonance imaging techniques, we reviewed the normal anatomy of the nuclei consisting of monoamine neurons such as dopaminergic, noradrenergic, and serotoninergic neurons and noted the changes in these nuclei that occur in some degenerative and psychiatric disorders. Multimodal MR images can directly or indirectly help in identifying the substantia nigra, locus ceruleus, and raphe nuclei that contain monoamine neurons. Neuromelanin-sensitive magnetic resonance imaging can detect signal alterations in the substantia nigra pars compacta and/or locus ceruleus that occur in Parkinson's disease and psychiatric disorders such as depression and schizophrenia. This technique seems to be promising for the noninvasive evaluation of the pathological or functional changes in the monoamine system that occur in degenerative and psychiatric disorders.

  12. Sensitivity of Locus Ceruleus Neurons to Reward Value for Goal-Directed Actions

    PubMed Central

    Richmond, Barry J.

    2015-01-01

    The noradrenergic nucleus locus ceruleus (LC) is associated classically with arousal and attention. Recent data suggest that it might also play a role in motivation. To study how LC neuronal responses are related to motivational intensity, we recorded 121 single neurons from two monkeys while reward size (one, two, or four drops) and the manner of obtaining reward (passive vs active) were both manipulated. The monkeys received reward under three conditions: (1) releasing a bar when a visual target changed color; (2) passively holding a bar; or (3) touching and releasing a bar. In the first two conditions, a visual cue indicated the size of the upcoming reward, and, in the third, the reward was constant through each block of 25 trials. Performance levels and lipping intensity (an appetitive behavior) both showed that the monkeys' motivation in the task was related to the predicted reward size. In conditions 1 and 2, LC neurons were activated phasically in relation to cue onset, and this activation strengthened with increasing expected reward size. In conditions 1 and 3, LC neurons were activated before the bar-release action, and the activation weakened with increasing expected reward size but only in task 1. These effects evolved as monkeys progressed through behavioral sessions, because increasing fatigue and satiety presumably progressively decreased the value of the upcoming reward. These data indicate that LC neurons integrate motivationally relevant information: both external cues and internal drives. The LC might provide the impetus to act when the predicted outcome value is low. PMID:25740528

  13. Dopamine modulates male sexual behavior in Japanese quail in part via actions on noradrenergic receptors.

    PubMed

    Cornil, Charlotte A; Dejace, Christel; Ball, Gregory F; Balthazart, Jacques

    2005-08-30

    In rats, dopamine (DA) facilitates male sexual behavior through its combined action on D1- and D2-like receptors, in the medial preoptic area (MPOA) as well as other brain areas. In Japanese quail, systemic injections of dopaminergic drugs suggested a similar pharmacology but central injections have never been performed. Recent electrophysiological experiments demonstrated that DA effects in the MPOA of quail are mediated mainly through the activation of alpha2-noradrenergic receptors. Previous studies of DA action on behavior used specific dopaminergic agonists/antagonists and therefore unintentionally avoided the potential cross-reaction with alpha2-receptors. The present study was thus designed to investigate directly the effects of DA on male sexual behavior and to test whether the interaction of DA with heterologous receptors affects this behavior. Intracerebroventricular (i.c.v.) injection of DA or NE inhibited copulation in a dose-dependent manner. Systemic injections of yohimbine, an alpha2-noradrenergic antagonist, modulated copulation in a bimodal manner depending on the dose injected. Interestingly, a behaviorally ineffective dose of yohimbine markedly reduced the inhibitory effects of DA when injected 15min before. Together, these results show for the first time that i.c.v. injections of DA itself inhibit male sexual behavior in quail and suggest that the interaction of DA with alpha2-receptors has behavioral significance.

  14. Staufen2 regulates neuronal target RNAs.

    PubMed

    Heraud-Farlow, Jacki E; Sharangdhar, Tejaswini; Li, Xiao; Pfeifer, Philipp; Tauber, Stefanie; Orozco, Denise; Hörmann, Alexandra; Thomas, Sabine; Bakosova, Anetta; Farlow, Ashley R; Edbauer, Dieter; Lipshitz, Howard D; Morris, Quaid D; Bilban, Martin; Doyle, Michael; Kiebler, Michael A

    2013-12-26

    RNA-binding proteins play crucial roles in directing RNA translation to neuronal synapses. Staufen2 (Stau2) has been implicated in both dendritic RNA localization and synaptic plasticity in mammalian neurons. Here, we report the identification of functionally relevant Stau2 target mRNAs in neurons. The majority of Stau2-copurifying mRNAs expressed in the hippocampus are present in neuronal processes, further implicating Stau2 in dendritic mRNA regulation. Stau2 targets are enriched for secondary structures similar to those identified in the 3' UTRs of Drosophila Staufen targets. Next, we show that Stau2 regulates steady-state levels of many neuronal RNAs and that its targets are predominantly downregulated in Stau2-deficient neurons. Detailed analysis confirms that Stau2 stabilizes the expression of one synaptic signaling component, the regulator of G protein signaling 4 (Rgs4) mRNA, via its 3' UTR. This study defines the global impact of Stau2 on mRNAs in neurons, revealing a role in stabilization of the levels of synaptic targets. Copyright © 2013 The Authors. Published by Elsevier Inc. All rights reserved.

  15. [Effect of non-selective alpha-adrenergic receptor antagonist nicergoline on the activity of neurons in the ventral lateral thalamic nucleus].

    PubMed

    Lukhanina, O P; Pil'kevych, N A

    2005-01-01

    In experiments on rats microionophoretic administration of nicergoline mainly showed the dual effect on the background activity of the ventrolateral thalamic nucleus (VL) neurons and their reactions evoked by the superior cerebellum peduncle stimulation: inhibitory under weak (2-10 nA) and excitatory under stronger (20-40 nA) currents. Microionophoresis (25 nA) of nicergoline led to decrease of the postexcitatory inhibitory processes during paired stimulation of the cerebellum fibers. Paired-pulse ratio (number of spikes in the short-latency neuronal responses elicited by the second pulse/number of spikes by the first pulse) increased, which support a presynaptic mode of drug action. Hence excitatory effect of nicergoline may be related to the blockade of the presynaptic alpha2-receptors, while inhibitory effect by the blockade of the postsynaptic alphal-receptors. Present data reveal the essential participation of the alpha-adrenoreceptor system in the modulation of background and evoked neuronal activity of the motor thalamus. The possible role of noradrenergic denervation in the development of movement disorders accompanying Parkinson's disease is discussed.

  16. The antidepressant-like effect of ethynyl estradiol is mediated by both serotonergic and noradrenergic systems in the forced swimming test.

    PubMed

    Vega-Rivera, N M; López-Rubalcava, C; Estrada-Camarena, E

    2013-10-10

    17α-Ethynyl-estradiol (EE2, a synthetic steroidal estrogen) induces antidepressant-like effects in the forced swimming test (FST) similar to those induced by 5-HT and noradrenaline reuptake inhibitors (dual antidepressants). However, the precise mechanism of action of EE2 has not been studied. In the present study, the participation of estrogen receptors (ERs) and the serotonergic and the noradrenergic presynaptic sites in the antidepressant-like action of EE2 was evaluated in the FST. The effects of the ER antagonist ICI 182,780 (10 μg/rat; i.c.v.), the serotonergic and noradrenergic terminal destruction with 5,7-dihydroxytryptamine (5,7-DHT; 200 μg/rat, i.c.v.), and N-(2-chloro-ethyl)-N-ethyl-2-bromobenzylamine (DSP4; 10mg/kg, i.p.) were studied in ovariectomized rats treated with EE2 and subjected to the FST. In addition, the participation of α2-adrenergic receptors in the antidepressant-like action of EE2 was explored using the selective α2-receptor antagonist idazoxan (0.25, 0.5 and 1.0mg/kg, i.p.). EE2 induced an antidepressant-like action characterized by a decrease in immobility behavior with a concomitant increase in swimming and climbing behaviors. The ER antagonist, 5,7-DHT, DSP4, and idazoxan blocked the effects of EE2 on the immobility behavior, whereas ICI 182,780 and 5,7-DHT affected swimming behavior. The noradrenergic compound DSP4 altered climbing behavior, while Idazoxan inhibited the increase of swimming and climbing behaviors induced by EE2. Our results suggest that the antidepressant-like action of EE2 implies a complex mechanism of action on monoaminergic systems and estrogen receptors. Copyright © 2013 IBRO. Published by Elsevier Ltd. All rights reserved.

  17. Genetically determined differences in noradrenergic function: The spontaneously hypertensive rat model.

    PubMed

    Sterley, Toni-Lee; Howells, Fleur M; Russell, Vivienne A

    2016-06-15

    While genetic predisposition is a major factor, it is not known how development of attention-deficit/hyperactivity disorder (ADHD) is modulated by early life stress. The spontaneously hypertensive rat (SHR) displays the behavioral characteristics of ADHD (poorly sustained attention, impulsivity, hyperactivity) and is the most widely studied genetic model of ADHD. We have previously shown that SHR have disturbances in the noradrenergic system and that the early life stress of maternal separation failed to produce anxiety-like behavior in SHR, contrary to control Sprague-Dawley and Wistar-Kyoto (WKY) who showed typical anxiety-like behavior in later life. In the present study we investigated the effect of maternal separation on approach behavior (response to a novel object in a familiar environment) in preadolescent SHR and WKY. We also investigated whether maternal separation altered GABAA and NMDA receptor-mediated regulation of norepinephrine release in preadolescent SHR and WKY hippocampus. We found that female SHR, similar to male SHR, exhibited greater exploratory activity than WKY. Maternal separation significantly increased GABAA receptor-mediated inhibition of glutamate-stimulated release of norepinephrine in male and female SHR hippocampus but had no significant effect in WKY. Maternal separation had opposite effects on NMDA receptor-mediated inhibition of norepinephrine release in SHR and WKY hippocampus, as it increased inhibition of both glutamate-stimulated and depolarization-evoked release in SHR hippocampus but not in WKY. The results of the present study show that noradrenergic function is similarly altered by the early life stress of maternal separation in male and female SHR, while GABA- and glutamate-regulation of norepinephrine release remained unaffected by maternal separation in the control, WKY, rat strain. This article is part of a Special Issue entitled SI: Noradrenergic System. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Distinct functional and temporal requirements for zebrafish Hdac1 during neural crest-derived craniofacial and peripheral neuron development.

    PubMed

    Ignatius, Myron S; Unal Eroglu, Arife; Malireddy, Smitha; Gallagher, Glen; Nambiar, Roopa M; Henion, Paul D

    2013-01-01

    The regulation of gene expression is accomplished by both genetic and epigenetic means and is required for the precise control of the development of the neural crest. In hdac1(b382) mutants, craniofacial cartilage development is defective in two distinct ways. First, fewer hoxb3a, dlx2 and dlx3-expressing posterior branchial arch precursors are specified and many of those that are consequently undergo apoptosis. Second, in contrast, normal numbers of progenitors are present in the anterior mandibular and hyoid arches, but chondrocyte precursors fail to terminally differentiate. In the peripheral nervous system, there is a disruption of enteric, DRG and sympathetic neuron differentiation in hdac1(b382) mutants compared to wildtype embryos. Specifically, enteric and DRG-precursors differentiate into neurons in the anterior gut and trunk respectively, while enteric and DRG neurons are rarely present in the posterior gut and tail. Sympathetic neuron precursors are specified in hdac1(b382) mutants and they undergo generic neuronal differentiation but fail to undergo noradrenergic differentiation. Using the HDAC inhibitor TSA, we isolated enzyme activity and temporal requirements for HDAC function that reproduce hdac1(b382) defects in craniofacial and sympathetic neuron development. Our study reveals distinct functional and temporal requirements for zebrafish hdac1 during neural crest-derived craniofacial and peripheral neuron development.

  19. [The alpha2delta subunit of the voltage-dependent calcium channel. A new pharmaceutical target for psychiatry and neurology].

    PubMed

    Wedekind, D; Bandelow, B

    2005-07-01

    Calcium channel blockers are substances used for treating high blood pressure and coronary heart disease. New medications have been developed that modulate calcium channels but also show promise in psychiatric and neurologic applications. Gabapentin and pregabalin bind to a subunit of calcium channels--the alpha2delta receptors--thereby reducing calcium influx to neurons. As a result, less glutamate is released from nerve endings that use excitatory amino acids as transmitters. This in turn reduces substance P-related activation of AMPA heteroreceptors on noradrenergic synapses, total transmitter release, and finally neuronal activity. That mechanism is the probable explanation for gabapentin's and pregabalin's usefulness in the treatment of neuropathic pain but also their possible anticonvulsive and anxiolytic effects.

  20. β-Adrenergic enhancement of neuronal excitability in the lateral amygdala is developmentally gated.

    PubMed

    Fink, Ann E; LeDoux, Joseph E

    2018-05-01

    Noradrenergic signaling in the amygdala is important for processing threats and other emotionally salient stimuli, and β-adrenergic receptor activation is known to enhance neuronal spiking in the lateral amygdala (LA) of juvenile animals. Nevertheless, intracellular recordings have not yet been conducted to determine the effect of β-adrenergic receptor activation on spike properties in the adult LA, despite the potential significance of developmental changes between adolescence and adulthood. Here we demonstrate that the β-adrenergic agonist isoproterenol (15 μM) enhances spike frequency in dorsal LA principal neurons of juvenile male C57BL/6 mice and fails to do so in strain- and sex-matched adults. Furthermore, we find that the age-dependent effect of isoproterenol on spike frequency is occluded by the GABA A receptor blocker picrotoxin (75 μM), suggesting that β-adrenergic receptors downregulate tonic inhibition specifically in juvenile animals. These findings indicate a significant shift during adolescence in the cellular mechanisms of β-adrenergic modulation in the amygdala. NEW & NOTEWORTHY β-Adrenergic receptors (β-ARs) in amygdala are important in processing emotionally salient stimuli. Most cellular recordings have examined juvenile animals, while behavioral data are often obtained from adults. We replicate findings showing that β-ARs enhance spiking of principal cells in the lateral amygdala of juveniles, but we fail to find this in adults. These findings have notable scientific and clinical implications regarding the noradrenergic modulation of threat processing, alterations of which underlie fear and anxiety disorders.

  1. One-single physical exercise session after object recognition learning promotes memory persistence through hippocampal noradrenergic mechanisms.

    PubMed

    da Silva de Vargas, Liane; Neves, Ben-Hur Souto das; Roehrs, Rafael; Izquierdo, Iván; Mello-Carpes, Pâmela

    2017-06-30

    Previously we showed the involvement of the hippocampal noradrenergic system in the consolidation and persistence of object recognition (OR) memory. Here we show that one-single physical exercise session performed immediately after learning promotes OR memory persistence and increases norepinephrine levels in the hippocampus. Additionally, effects of exercise on memory are avoided by an intra-hippocampal beta-adrenergic antagonist infusion. Taken together, these results suggest that exercise effects on memory can be related to noradrenergic mechanisms and acute physical exercise can be a non-pharmacological intervention to assist memory consolidation and persistence, with few or no side effects. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. The GluN2A Subunit Regulates Neuronal NMDA receptor-Induced Microglia-Neuron Physical Interactions.

    PubMed

    Eyo, Ukpong B; Bispo, Ashley; Liu, Junting; Sabu, Sruchika; Wu, Rong; DiBona, Victoria L; Zheng, Jiaying; Murugan, Madhuvika; Zhang, Huaye; Tang, Yamei; Wu, Long-Jun

    2018-01-16

    Microglia are known to engage in physical interactions with neurons. However, our understanding of the detailed mechanistic regulation of microglia-neuron interactions is incomplete. Here, using high resolution two photon imaging, we investigated the regulation of NMDA receptor-induced microglia-neuron physical interactions. We found that the GluN2A inhibitor NVPAAM007, but not the GluN2B inhibitor ifenprodil, blocked the occurrence of these interactions. Consistent with the well-known developmental regulation of the GluN2A subunit, these interactions are absent in neonatal tissues. Furthermore, consistent with a preferential synaptic localization of GluN2A subunits, there is a differential sensitivity of their occurrence between denser (stratum radiatum) and less dense (stratum pyramidale) synaptic sub-regions of the CA1. Finally, consistent with differentially expressed GluN2A subunits in the CA1 and DG areas of the hippocampus, these interactions could not be elicited in the DG despite robust microglial chemotactic capabilities. Together, these results enhance our understanding of the mechanistic regulation of NMDA receptor-dependent microglia-neuronal physical interactions phenomena by the GluN2A subunit that may be relevant in the mammalian brain during heightened glutamatergic neurotransmission such as epilepsy and ischemic stroke.

  3. Noradrenergic Action in Prefrontal Cortex in the Late Stage of Memory Consolidation

    ERIC Educational Resources Information Center

    Tronel, Sophie; Feenstra, Matthijs G. P.; Sara, Susan J.

    2004-01-01

    These experiments investigated the role of the noradrenergic system in the late stage of memory consolidation and in particular its action at beta receptors in the prelimbic region (PL) of the prefrontal cortex in the hours after training. Rats were trained in a rapidly acquired, appetitively motivated foraging task based on olfactory…

  4. Foxp2 regulates neuronal differentiation and neuronal subtype specification.

    PubMed

    Chiu, Yi-Chi; Li, Ming-Yang; Liu, Yuan-Hsuan; Ding, Jing-Ya; Yu, Jenn-Yah; Wang, Tsu-Wei

    2014-07-01

    Mutations of the transcription factor FOXP2 in humans cause a severe speech and language disorder. Disruption of Foxp2 in songbirds or mice also leads to deficits in song learning or ultrasonic vocalization, respectively. These data suggest that Foxp2 plays important roles in the developing nervous system. However, the mechanism of Foxp2 in regulating neural development remains elusive. In the current study, we found that Foxp2 increased neuronal differentiation without affecting cell proliferation and cell survival in primary neural progenitors from embryonic forebrains. Foxp2 induced the expression of platelet-derived growth factor receptor α, which mediated the neurognic effect of Foxp2. In addition, Foxp2 positively regulated the differentiation of medium spiny neurons derived from the lateral ganglionic eminence and negatively regulated the formation of interneurons derived from dorsal medial ganglionic eminence by interacting with the Sonic hedgehog pathway. Taken together, our results suggest that Foxp2 regulates multiple aspects of neuronal development in the embryonic forebrain. © 2014 Wiley Periodicals, Inc.

  5. Effect of Noradrenergic Neurotoxin DSP-4 and Maprotiline on Heart Rate Spectral Components in Stressed and Resting Rats.

    PubMed

    Kur'yanova, E V; Zhukova, Yu D; Teplyi, D L

    2017-07-01

    The effects of intraperitoneal DSP-4 (N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine, a noradrenergic neurotoxin) and maprotiline (an inhibitor of norepinephrine reuptake in synapses) on spectral components of heart rhythm variability were examined in outbred male and female rats treated with these agents in daily doses of 10 mg/kg for 3 days. At rest, DSP-4 elevated LF and VLF spectral components in male and female rats. Maprotiline elevated LF and VLF components in males at rest, increased HR and reduced all spectral components in resting females. Stress against the background of DSP-4 treatment sharply increased heart rate and reduced the powers of all spectral components (especially LF and VLF components). In maprotiline-treated rats, stress increased the powers of LF and VLF components. Thus, the central noradrenergic system participates in the formation of LF and VLF spectral components of heart rate variability at rest and especially during stressful stimulation, which can determine the phasic character of changes in the heart rate variability observed in stressed organism.

  6. Bax regulates neuronal Ca2+ homeostasis.

    PubMed

    D'Orsi, Beatrice; Kilbride, Seán M; Chen, Gang; Perez Alvarez, Sergio; Bonner, Helena P; Pfeiffer, Shona; Plesnila, Nikolaus; Engel, Tobias; Henshall, David C; Düssmann, Heiko; Prehn, Jochen H M

    2015-01-28

    Excessive Ca(2+) entry during glutamate receptor overactivation ("excitotoxicity") induces acute or delayed neuronal death. We report here that deficiency in bax exerted broad neuroprotection against excitotoxic injury and oxygen/glucose deprivation in mouse neocortical neuron cultures and reduced infarct size, necrotic injury, and cerebral edema formation after middle cerebral artery occlusion in mice. Neuronal Ca(2+) and mitochondrial membrane potential (Δψm) analysis during excitotoxic injury revealed that bax-deficient neurons showed significantly reduced Ca(2+) transients during the NMDA excitation period and did not exhibit the deregulation of Δψm that was observed in their wild-type (WT) counterparts. Reintroduction of bax or a bax mutant incapable of proapoptotic oligomerization equally restored neuronal Ca(2+) dynamics during NMDA excitation, suggesting that Bax controlled Ca(2+) signaling independently of its role in apoptosis execution. Quantitative confocal imaging of intracellular ATP or mitochondrial Ca(2+) levels using FRET-based sensors indicated that the effects of bax deficiency on Ca(2+) handling were not due to enhanced cellular bioenergetics or increased Ca(2+) uptake into mitochondria. We also observed that mitochondria isolated from WT or bax-deficient cells similarly underwent Ca(2+)-induced permeability transition. However, when Ca(2+) uptake into the sarco/endoplasmic reticulum was blocked with the Ca(2+)-ATPase inhibitor thapsigargin, bax-deficient neurons showed strongly elevated cytosolic Ca(2+) levels during NMDA excitation, suggesting that the ability of Bax to support dynamic ER Ca(2+) handling is critical for cell death signaling during periods of neuronal overexcitation. Copyright © 2015 the authors 0270-6474/15/351706-17$15.00/0.

  7. Adolescent social isolation increases anxiety-like behavior and ethanol intake and impairs fear extinction in adulthood: possible role of disrupted noradrenergic signaling

    PubMed Central

    Skelly, M. J.; Chappell, A. E.; Carter, E.; Weiner, J. L.

    2015-01-01

    Alcohol use disorder, anxiety disorders, and post-traumatic stress disorder (PTSD) are highly comorbid, and exposure to chronic stress during adolescence may increase the incidence of these conditions in adulthood. Efforts to identify the common stress-related mechanisms driving these disorders have been hampered, in part, by a lack of reliable preclinical models that replicate their comorbid symptomatology. Prior work by us, and others, has shown that adolescent social isolation increases anxiety-like behaviors and voluntary ethanol consumption in adult male Long-Evans rats. Here we examined whether social isolation also produces deficiencies in extinction of conditioned fear, a hallmark symptom of PTSD. Additionally, as disrupted noradrenergic signaling may contribute to alcoholism, we examined the effect of anxiolytic medications that target noradrenergic signaling on ethanol intake following adolescent social isolation. Our results confirm and extend previous findings that adolescent social isolation increases anxiety-like behavior and enhances ethanol intake and preference in adulthood. Additionally, social isolation is associated with a significant deficit in the extinction of conditioned fear and a marked increase in the ability of noradrenergic therapeutics to decrease ethanol intake. These results suggest that adolescent social isolation not only leads to persistent increases in anxiety-like behaviors and ethanol consumption, but also disrupts fear extinction, and as such may be a useful preclinical model of stress-related psychopathology. Our data also suggest that disrupted noradrenergic signaling may contribute to escalated ethanol drinking following social isolation, thus further highlighting the potential utility of noradrenergic therapeutics in treating the deleterious behavioral sequelae associated with early life stress. PMID:26044636

  8. Orphanin FQ/Nociceptin Interacts with the Basolateral Amygdala Noradrenergic System in Memory Consolidation

    ERIC Educational Resources Information Center

    Roozendaal, Benno; Lengvilas, Ray; McGaugh, James L.; Civelli, Olivier; Reinscheid, Rainer K.

    2007-01-01

    Extensive evidence indicates that the basolateral complex of the amygdala (BLA) mediates hormonal and neurotransmitter effects on the consolidation of emotionally influenced memory and that such modulatory influences involve noradrenergic activation of the BLA. As the BLA also expresses a high density of receptors for orphanin FQ/nociceptin…

  9. Both a Nicotinic Single Nucleotide Polymorphism (SNP) and a Noradrenergic SNP Modulate Working Memory Performance when Attention Is Manipulated

    ERIC Educational Resources Information Center

    Greenwood, Pamela M.; Sundararajan, Ramya; Lin, Ming-Kuan; Kumar, Reshma; Fryxell, Karl J.; Parasuraman, Raja

    2009-01-01

    We investigated the relation between the two systems of visuospatial attention and working memory by examining the effect of normal variation in cholinergic and noradrenergic genes on working memory performance under attentional manipulation. We previously reported that working memory for location was impaired following large location precues,…

  10. Increased Opioid Dependence in a Mouse Model of Panic Disorder

    PubMed Central

    Gallego, Xavier; Murtra, Patricia; Zamalloa, Teresa; Canals, Josep Maria; Pineda, Joseba; Amador-Arjona, Alejandro; Maldonado, Rafael; Dierssen, Mara

    2009-01-01

    Panic disorder is a highly prevalent neuropsychiatric disorder that shows co-occurrence with substance abuse. Here, we demonstrate that TrkC, the high-affinity receptor for neurotrophin-3, is a key molecule involved in panic disorder and opiate dependence, using a transgenic mouse model (TgNTRK3). Constitutive TrkC overexpression in TgNTRK3 mice dramatically alters spontaneous firing rates of locus coeruleus (LC) neurons and the response of the noradrenergic system to chronic opiate exposure, possibly related to the altered regulation of neurotrophic peptides observed. Notably, TgNTRK3 LC neurons showed an increased firing rate in saline-treated conditions and profound abnormalities in their response to met5-enkephalin. Behaviorally, chronic morphine administration induced a significantly increased withdrawal syndrome in TgNTRK3 mice. In conclusion, we show here that the NT-3/TrkC system is an important regulator of neuronal firing in LC and could contribute to the adaptations of the noradrenergic system in response to chronic opiate exposure. Moreover, our results indicate that TrkC is involved in the molecular and cellular changes in noradrenergic neurons underlying both panic attacks and opiate dependence and support a functional endogenous opioid deficit in panic disorder patients. PMID:20204153

  11. A novel CaV2.2 channel inhibition by piracetam in peripheral and central neurons.

    PubMed

    Bravo-Martínez, Jorge; Arenas, Isabel; Vivas, Oscar; Rebolledo-Antúnez, Santiago; Vázquez-García, Mario; Larrazolo, Arturo; García, David E

    2012-10-01

    No mechanistic actions for piracetam have been documented to support its nootropic effects. Voltage-gated calcium channels have been proposed as a promising pharmacological target of nootropic drugs. In this study, we investigated the effect of piracetam on Ca(V)2.2 channels in peripheral neurons, using patch-clamp recordings from cultured superior cervical ganglion neurons. In addition, we tested if Ca(V)2.2 channel inhibition could be related with the effects of piracetam on central neurons. We found that piracetam inhibited native Ca(V)2.2 channels in superior cervical ganglion neurons in a dose-dependent manner, with an IC(50) of 3.4 μmol/L and a Hill coefficient of 1.1. GDPβS dialysis did not prevent piracetam-induced inhibition of Ca(V)2.2 channels and G-protein-coupled receptor activation by noradrenaline did not occlude the piracetam effect. Piracetam altered the biophysical characteristics of Ca(V)2.2 channel such as facilitation ratio. In hippocampal slices, piracetam and ω-conotoxin GVIA diminished the frequency of excitatory postsynaptic potentials and action potentials. Our results provide evidence of piracetam's actions on Ca(V)2.2 channels in peripheral neurons, which might explain some of its nootropic effects in central neurons.

  12. Too much of a good thing: blocking noradrenergic facilitation in medial prefrontal cortex prevents the detrimental effects of chronic stress on cognition.

    PubMed

    Jett, Julianne D; Morilak, David A

    2013-03-01

    Cognitive impairments associated with dysfunction of the medial prefrontal cortex (mPFC) are prominent in stress-related psychiatric disorders. We have shown that enhancing noradrenergic tone acutely in the rat mPFC facilitated extra-dimensional (ED) set-shifting on the attentional set-shifting test (AST), whereas chronic unpredictable stress (CUS) impaired ED. In this study, we tested the hypothesis that the acute facilitatory effect of norepinephrine (NE) in mPFC becomes detrimental when activated repeatedly during CUS. Using microdialysis, we showed that the release of NE evoked in mPFC by acute stress was unchanged at the end of CUS treatment. Thus, to then determine if repeated elicitation of this NE activity in mPFC during CUS may have contributed to the ED deficit, we infused a cocktail of α(1)-, β(1)-, and β(2)-adrenergic receptor antagonists into the mPFC prior to each CUS session, then tested animals drug free on the AST. Antagonist treatment prevented the CUS-induced ED deficit, suggesting that NE signaling during CUS compromised mPFC function. We confirmed that this was not attributable to sensitization of adrenergic receptor function following chronic antagonist treatment, by administering an additional microinjection into the mPFC immediately prior to ED testing. Acute antagonist treatment did not reverse the beneficial effects of chronic drug treatment during CUS, nor have any effect on baseline ED performance in chronic vehicle controls. Thus, we conclude that blockade of noradrenergic receptors in mPFC protected against the detrimental cognitive effects of CUS, and that repeated elicitation of noradrenergic facilitatory activity is one mechanism by which chronic stress may promote mPFC cognitive dysfunction.

  13. Interactions between Brainstem Noradrenergic Neurons and the Nucleus Accumbens Shell in Modulating Memory for Emotionally Arousing Events

    ERIC Educational Resources Information Center

    Kerfoot, Erin C.; Williams, Cedric L.

    2011-01-01

    The nucleus accumbens shell (NAC) receives axons containing dopamine-[beta]-hydroxylase that originate from brainstem neurons in the nucleus of the solitary tract (NTS). Recent findings show that memory enhancement produced by stimulating NTS neurons after learning may involve interactions with the NAC. However, it is unclear whether these…

  14. Differential neuronal vulnerability identifies IGF-2 as a protective factor in ALS

    PubMed Central

    Allodi, Ilary; Comley, Laura; Nichterwitz, Susanne; Nizzardo, Monica; Simone, Chiara; Benitez, Julio Aguila; Cao, Ming; Corti, Stefania; Hedlund, Eva

    2016-01-01

    The fatal disease amyotrophic lateral sclerosis (ALS) is characterized by the loss of somatic motor neurons leading to muscle wasting and paralysis. However, motor neurons in the oculomotor nucleus, controlling eye movement, are for unknown reasons spared. We found that insulin-like growth factor 2 (IGF-2) was maintained in oculomotor neurons in ALS and thus could play a role in oculomotor resistance in this disease. We also showed that IGF-1 receptor (IGF-1R), which mediates survival pathways upon IGF binding, was highly expressed in oculomotor neurons and on extraocular muscle endplate. The addition of IGF-2 induced Akt phosphorylation, glycogen synthase kinase-3β phosphorylation and β-catenin levels while protecting ALS patient motor neurons. IGF-2 also rescued motor neurons derived from spinal muscular atrophy (SMA) patients from degeneration. Finally, AAV9::IGF-2 delivery to muscles of SOD1G93A ALS mice extended life-span by 10%, while preserving motor neurons and inducing motor axon regeneration. Thus, our studies demonstrate that oculomotor-specific expression can be utilized to identify candidates that protect vulnerable motor neurons from degeneration. PMID:27180807

  15. Pleiotrophin antagonizes Brd2 during neuronal differentiation

    PubMed Central

    Garcia-Gutierrez, Pablo; Juarez-Vicente, Francisco; Wolgemuth, Debra J.; Garcia-Dominguez, Mario

    2014-01-01

    ABSTRACT Bromodomain-containing protein 2 (Brd2) is a BET family chromatin adaptor required for expression of cell-cycle-associated genes and therefore involved in cell cycle progression. Brd2 is expressed in proliferating neuronal progenitors, displays cell-cycle-stimulating activity and, when overexpressed, impairs neuronal differentiation. Paradoxically, Brd2 is also detected in differentiating neurons. To shed light on the role of Brd2 in the transition from cell proliferation to differentiation, we had previously looked for proteins that interacted with Brd2 upon induction of neuronal differentiation. Surprisingly, we identified the growth factor pleiotrophin (Ptn). Here, we show that Ptn antagonized the cell-cycle-stimulating activity associated with Brd2, thus enhancing induced neuronal differentiation. Moreover, Ptn knockdown reduced neuronal differentiation. We analyzed Ptn-mediated antagonism of Brd2 in a cell differentiation model and in two embryonic processes associated with the neural tube: spinal cord neurogenesis and neural crest migration. Finally, we investigated the mechanisms of Ptn-mediated antagonism and determined that Ptn destabilizes the association of Brd2 with chromatin. Thus, Ptn-mediated Brd2 antagonism emerges as a modulation system accounting for the balance between cell proliferation and differentiation in the vertebrate nervous system. PMID:24695857

  16. Is the Noradrenergic Symptom Cluster a Valid Construct in Adjunctive Treatment of Major Depressive Disorder?

    PubMed

    Stauffer, Virginia L; Liu, Peng; Goldberger, Celine; Marangell, Lauren B; Nelson, Craig; Gorwood, Philip; Fava, Maurizio

    2017-03-01

    To identify symptoms potentially representative of a noradrenergic symptom cluster as possible predictors of response to the selective norepinephrine reuptake inhibitor (NRI) edivoxetine when used as monotherapy or adjunctive treatment in patients with DSM-IV-TR major depressive disorder (MDD). Pooled data from 4 adjunctive treatment trials (selective serotonin reuptake inhibitor [SSRI] + edivoxetine 6-18 mg/d vs SSRI + placebo; N = 2,066) and data from 1 monotherapy trial (edivoxetine 6-18 mg/d versus placebo; N = 495) were used to identify predictors of response related to noradrenergic symptoms using a resampling-based ensemble tree method. The trials were conducted from 2008 to 2013. In the pooled adjunctive trials, no subgroup was identified that demonstrated a greater edivoxetine-placebo treatment difference than the overall patient cohort. In the edivoxetine monotherapy trial, no subgroup showing greater mean edivoxetine-placebo differences on the Montgomery-Asberg Depression Rating Scale versus the overall patient cohort was identified; a subgroup (67%) with high b​aseline Massachusetts General Hospital Cognitive and Physical Functioning Questionnaire (CPFQ) total score (≥ 28) showed statistically significantly (P = .02) greater mean edivoxetine-placebo differences on the Sheehan Disability Scale versus the overall patient cohort, and subgroups with baseline CPFQ total score ≥ 28 (65%), CPFQ cognition dimension score ≥ 16 (63%), or CPFQ physical dimension score ≥ 13 (59%) showed statistically significantly (P ≤ .025) greater mean edivoxetine-placebo differences on the CPFQ total score versus the overall patient cohort. While we could not identify symptoms predictive of response to the selective NRI edivoxetine used as adjunctive treatment, impaired cognition and physical symptoms may predict greater improvement during monotherapy. ClinicalTrials.gov identifiers: NCT00840034, NCT01173601, NCT01187407, NCT01185340, NCT00795821. © Copyright 2017

  17. Pressor response to L-cysteine injected into the cisterna magna of conscious rats involves recruitment of hypothalamic vasopressinergic neurons.

    PubMed

    Takemoto, Yumi

    2013-03-01

    The sulfur-containing non-essential amino acid L-cysteine injected into the cisterna magna of adult conscious rats produces an increase in blood pressure. The present study examined if the pressor response to L-cysteine is stereospecific and involves recruitment of hypothalamic vasopressinergic neurons and medullary noradrenergic A1 neurons. Intracisternally injected D-cysteine produced no cardiovascular changes, while L-cysteine produced hypertension and tachycardia in freely moving rats, indicating the stereospecific hemodynamic actions of L-cysteine via the brain. The double labeling immunohistochemistry combined with c-Fos detection as a marker of neuronal activation revealed significantly higher numbers of c-Fos-positive vasopressinergic neurons both in the supraoptic and paraventricular nuclei and tyrosine hydroxylase containing medullary A1 neurons, of L-cysteine-injected rats than those injected with D-cysteine as iso-osmotic control. The results indicate that the cardiovascular responses to intracisternal injection of L-cysteine in the conscious rat are stereospecific and include recruitment of hypothalamic vasopressinergic neurons both in the supraoptic and paraventricular nuclei, as well as of medullary A1 neurons. The findings may suggest a potential function of L-cysteine as an extracellular signal such as neuromodulators in central regulation of blood pressure.

  18. Adolescent social isolation increases anxiety-like behavior and ethanol intake and impairs fear extinction in adulthood: Possible role of disrupted noradrenergic signaling.

    PubMed

    Skelly, M J; Chappell, A E; Carter, E; Weiner, J L

    2015-10-01

    Alcohol use disorder, anxiety disorders, and post-traumatic stress disorder (PTSD) are highly comorbid, and exposure to chronic stress during adolescence may increase the incidence of these conditions in adulthood. Efforts to identify the common stress-related mechanisms driving these disorders have been hampered, in part, by a lack of reliable preclinical models that replicate their comorbid symptomatology. Prior work by us, and others, has shown that adolescent social isolation increases anxiety-like behaviors and voluntary ethanol consumption in adult male Long-Evans rats. Here we examined whether social isolation also produces deficiencies in extinction of conditioned fear, a hallmark symptom of PTSD. Additionally, as disrupted noradrenergic signaling may contribute to alcoholism, we examined the effect of anxiolytic medications that target noradrenergic signaling on ethanol intake following adolescent social isolation. Our results confirm and extend previous findings that adolescent social isolation increases anxiety-like behavior and enhances ethanol intake and preference in adulthood. Additionally, social isolation is associated with a significant deficit in the extinction of conditioned fear and a marked increase in the ability of noradrenergic therapeutics to decrease ethanol intake. These results suggest that adolescent social isolation not only leads to persistent increases in anxiety-like behaviors and ethanol consumption, but also disrupts fear extinction, and as such may be a useful preclinical model of stress-related psychopathology. Our data also suggest that disrupted noradrenergic signaling may contribute to escalated ethanol drinking following social isolation, thus further highlighting the potential utility of noradrenergic therapeutics in treating the deleterious behavioral sequelae associated with early life stress. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. The dorsal tegmental noradrenergic projection: an analysis of its role in maze learning.

    PubMed

    Roberts, D C; Price, M T; Fibiger, H C

    1976-04-01

    The hypothesis that the noradrenergic projection from the locus coeruleus (LC) to the cerebral cortex and hippocampus is an important neural substrate for learning was evaluated. Maze performance was studied in rats receiving either electrolytic lesions of LC or 6-hydroxydopamine (6-OHDA) lesions of the dorsal tegmental noradrenergic projection. The LC lesions did not disrupt the acquisition of a running response for food reinforcement in an L-shaped runway, even though hippocampal-cortical norepinephrine (NE) was reduced to 29%. Greater telencephalic NE depletions (to 6% of control levels) produced by 6-OHDA also failed to disrupt the acquisition of this behavior or to impair the acquisition of a food-reinforced position habit in a T-maze. Neither locomotor activity nor habituation to a novel environment was affected by the 6-OHDA lesions. Rats with such lesions were, however, found to be significantly more distractible than were controls during the performance of a previously trained response. The hypothesis that telencephalic NE is of fundamental importance in learning was not supported. The data suggest that this system may participate in attentional mechanisms.

  20. Selective inhibition of dopamine-beta-hydroxylase enhances dopamine release from noradrenergic terminals in the medial prefrontal cortex.

    PubMed

    Devoto, Paola; Flore, Giovanna; Saba, Pierluigi; Frau, Roberto; Gessa, Gian L

    2015-10-01

    Disulfiram has been claimed to be useful in cocaine addiction therapy, its efficacy being attributed to dopamine-beta-hydroxylase (DBH) inhibition. Our previous results indicate that disulfiram and the selective DBH inhibitor nepicastat increase extracellular dopamine (DA) in the rat medial prefrontal cortex (mPFC), and markedly potentiated cocaine-induced increase. Concomitantly, in rats with cocaine self-administration history, cocaine-seeking behavior induced by drug priming was prevented, probably through overstimulation of D1 receptors due to the DA increase. The present research was aimed at studying the neurochemical mechanisms originating the enhanced DA release. Noradrenergic system ablation was attained by intracerebroventricular (i.c.v.) administration of the neurotoxin anti-DBH-saporin (aDBH-sap). DA, noradrenaline (NA), and DOPAC were assessed by HPLC after ex vivo tissue extraction or in vivo microdialysis. Control and denervated rats were subjected to microdialysis in the mPFC and caudate nucleus to evaluate the effect of nepicastat-cocaine combination on extracellular DA levels and their regulation by α2-adrenoceptors. Fifteen days after neurotoxin or its vehicle administration, tissue and extracellular NA were reduced to less than 2% the control value, while extracellular DA was increased by approximately 100%. In control rats, nepicastat given alone and in combination with cocaine increased extracellular DA by about 250% and 1100%, respectively. In denervated rats, nepicastat slightly affected extracellular DA, while in combination with cocaine increased extracellular DA by 250%. No differences were found in the caudate nucleus. Clonidine almost totally reversed the extracellular DA elevation produced by nepicastat-cocaine combination, while it was ineffective in denervated rats. This research shows that the increase of extracellular DA produced by nepicastat alone or in combination with cocaine was prevented by noradrenergic denervation. The

  1. Facilitation of Learning by Social-Emotional Feedback in Humans Is Beta-Noradrenergic-Dependent

    ERIC Educational Resources Information Center

    Mihov, Yoan; Mayer, Simon; Musshoff, Frank; Maier, Wolfgang; Kendrick, Keith M.; Hurlemann, Rene

    2010-01-01

    Adaptive behavior in dynamic environments critically depends on the ability to learn rapidly and flexibly from the outcomes of prior choices. In social environments, facial expressions of emotion often serve as performance feedback and thereby guide declarative learning. Abundant evidence implicates beta-noradrenergic signaling in the modulatory…

  2. Conditional Depletion of Hippocampal Brain-Derived Neurotrophic Factor Exacerbates Neuropathology in a Mouse Model of Alzheimer's Disease.

    PubMed

    Braun, David J; Kalinin, Sergey; Feinstein, Douglas L

    2017-01-01

    Damage occurring to noradrenergic neurons in the locus coeruleus (LC) contributes to the evolution of neuroinflammation and neurodegeneration in a variety of conditions and diseases. One cause of LC damage may be loss of neurotrophic support from LC target regions. We tested this hypothesis by conditional unilateral knockout of brain-derived neurotrophic factor (BDNF) in adult mice. To evaluate the consequences of BDNF loss in the context of neurodegeneration, the mice harbored familial mutations for human amyloid precursor protein and presenilin-1. In these mice, BDNF depletion reduced tyrosine hydroxylase staining, a marker of noradrenergic neurons, in the rostral LC. BDNF depletion also reduced noradrenergic innervation in the hippocampus, the frontal cortex, and molecular layer of the cerebellum, assessed by staining for dopamine beta hydroxylase. BDNF depletion led to an increase in cortical amyloid plaque numbers and size but was without effect on plaque numbers in the striatum, a site with minimal innervation from the LC. Interestingly, cortical Iba1 staining for microglia was reduced by BDNF depletion and was correlated with reduced dopamine beta hydroxylase staining. These data demonstrate that reduction of BDNF levels in an LC target region can cause retrograde damage to LC neurons, leading to exacerbation of neuropathology in distinct LC target areas. Methods to reduce BDNF loss or supplement BDNF levels may be of value to reduce neurodegenerative processes normally limited by LC noradrenergic activities.

  3. Involvement of histaminergic and noradrenergic receptors in the oxytocin-induced food intake in neonatal meat-type chicks.

    PubMed

    Mirnaghizadeh, Seyed Vahid; Zendehdel, Morteza; Babapour, Vahab

    2017-03-01

    Oxytocin neurons have a physiological role in food intake and energy balance. Several studies have shown that central histaminergic and adrenergic systems synapse on oxytocin neurons but there is no information for their interaction on food intake regulation in birds. The purpose of this study was to examine the effects of intracerebroventricular (ICV) injection of α-fluoromethylhistidine (α-FMH, histidine decarboxylase inhibitor), chlorpheniramine (histamine H1 receptors antagonist), famotidine (histamine H2 receptors antagonist), thioperamide (histamine H3 receptors antagonist), prazosin (α1 receptor antagonist), yohimbine (α2 receptor antagonist), metoprolol (β1 adrenergic receptor antagonist), ICI 118,551 (β2 adrenergic receptor antagonist) and SR59230R (β3 adrenergic receptor antagonist) on oxytocin-induced hypophagia in 3-h food-deprived (FD 3 ) neonatal broiler chicken. In Experiment 1, 3 h-fasted chicks were given an ICV injection of saline, α-FMH (250 nmol), oxytocin (10 μg) and co-injection of α-FMH + oxytocin. Experiments 2-9 were similar to experiment 1 except birds were injected with chlorpheniramine (300 nmol), famotidine (82 nmol), thioperamide (300 nmol), prazosin (10 nmol), yohimbine (13 nmol), metoprolol (24 nmol), ICI 118,551(5 nmol) and SR59230R (20 nmol) instead of α-FMH, respectively. After injection cumulative food intake was measured until 120 min post injection. According to the results, ICV injection of oxytocin significantly decreased food intake in broiler chickens (P < 0.001). ICV injection of α-FMH significantly attenuated hypophagic effect of oxytocin (P < 0.001). Also, co-injection of chlorpheniramine plus oxytocin significantly decreased the effect of oxytocin on food intake (P < 0.001). Co-administration of thioperamide and oxytocin significantly amplified hypophagic effect of oxytocin in chickens (P < 0.001). In addition, ICI 118,551 attenuated hypophagic effect of oxytocin (P < 0.001); while

  4. Noradrenergic α1 Receptor Antagonist Treatment Attenuates Positive Subjective Effects of Cocaine in Humans: A Randomized Trial

    PubMed Central

    Newton, Thomas F.; De La Garza, Richard; Brown, Gregory; Kosten, Thomas R.; Mahoney, James J.; Haile, Colin N.

    2012-01-01

    Background Preclinical research implicates dopaminergic and noradrenergic mechanisms in mediating the reinforcing effects of drugs of abuse, including cocaine. The objective of this study was to evaluate the impact of treatment with the noradrenergic α1 receptor antagonist doxazosin on the positive subjective effects of cocaine. Methods Thirteen non-treatment seeking, cocaine-dependent volunteers completed this single-site, randomized, placebo-controlled, within-subjects study. In one study phase volunteers received placebo and in the other they received doxazosin, with the order counterbalanced across participants. Study medication was masked by over-encapsulating doxazosin tablets and matched placebo lactose served as the control. Study medication treatment was initiated at 1 mg doxazosin or equivalent number of placebo capsules PO/day and increased every three days by 1 mg. After receiving 4 mg doxazosin or equivalent number of placebo capsules participants received masked doses of 20 and 40 mg cocaine IV in that order with placebo saline randomly interspersed to maintain the blind. Results Doxazosin treatment was well tolerated and doxazosin alone produced minimal changes in heart rate and blood pressure. During treatment with placebo, cocaine produced dose-dependent increases in subjective effect ratings of “high”, “stimulated”, “like cocaine”, “desire cocaine”, “any drug effect”, and “likely to use cocaine if had access” (p<.001). Doxazosin treatment significantly attenuated the effects of 20 mg cocaine on ratings of “stimulated”, “like cocaine”, and “likely to use cocaine if had access” (p<.05). There were trends for doxazosin to reduce ratings of “stimulated”, “desire cocaine”, and “likely to use cocaine if had access” (p<.10). Conclusions Medications that block noradrenergic α1 receptors, such as doxazosin, may be useful as treatments for cocaine dependence, and should be evaluated further. Trial

  5. Neuronal activity in primate dorsal anterior cingulate cortex signals task conflict and predicts adjustments in pupil-linked arousal

    PubMed Central

    Ebitz, R. Becket; Platt, Michael L.

    2014-01-01

    Summary Whether driving a car, shopping for food, or paying attention in a classroom of boisterous teenagers, it’s often hard to maintain focus on goals in the face of distraction. Brain imaging studies in humans implicate the dorsal anterior cingulate cortex (dACC) in regulating the conflict between goals and distractors. Here we show for the first time that single dACC neurons signal conflict between task goals and distractors in the rhesus macaque, particularly for biologically-relevant social stimuli. For some neurons, task conflict signals predicted subsequent changes in pupil size—a peripheral index of arousal linked to noradrenergic tone—associated with reduced distractor interference. dACC neurons also responded to errors and these signals predicted adjustments in pupil size. These findings provide the first neurophysiological endorsement of the hypothesis that dACC regulates conflict, in part, via modulation of pupil-linked processes such as arousal. PMID:25654259

  6. Projection specificity in heterogeneous locus coeruleus cell populations: implications for learning and memory

    PubMed Central

    Uematsu, Akira; Tan, Bao Zhen

    2015-01-01

    Noradrenergic neurons in the locus coeruleus (LC) play a critical role in many functions including learning and memory. This relatively small population of cells sends widespread projections throughout the brain including to a number of regions such as the amygdala which is involved in emotional associative learning and the medial prefrontal cortex which is important for facilitating flexibility when learning rules change. LC noradrenergic cells participate in both of these functions, but it is not clear how this small population of neurons modulates these partially distinct processes. Here we review anatomical, behavioral, and electrophysiological studies to assess how LC noradrenergic neurons regulate these different aspects of learning and memory. Previous work has demonstrated that subpopulations of LC noradrenergic cells innervate specific brain regions suggesting heterogeneity of function in LC neurons. Furthermore, noradrenaline in mPFC and amygdala has distinct effects on emotional learning and cognitive flexibility. Finally, neural recording data show that LC neurons respond during associative learning and when previously learned task contingencies change. Together, these studies suggest a working model in which distinct and potentially opposing subsets of LC neurons modulate particular learning functions through restricted efferent connectivity with amygdala or mPFC. This type of model may provide a general framework for understanding other neuromodulatory systems, which also exhibit cell type heterogeneity and projection specificity. PMID:26330494

  7. Selective noradrenaline depletion impairs working memory and hippocampal neurogenesis.

    PubMed

    Coradazzi, Marino; Gulino, Rosario; Fieramosca, Francesco; Falzacappa, Lucia Verga; Riggi, Margherita; Leanza, Giampiero

    2016-12-01

    Noradrenergic neurons in the locus coeruleus play a role in learning and memory, and their loss is an early event in Alzheimer's disease pathogenesis. Moreover, noradrenaline may sustain hippocampal neurogenesis; however, whether are these events related is still unknown. Four to five weeks following the selective immunotoxic ablation of locus coeruleus neurons, young adult rats underwent reference and working memory tests, followed by postmortem quantitative morphological analyses to assess the extent of the lesion, as well as the effects on proliferation and/or survival of neural progenitors in the hippocampus. When tested in the Water Maze task, lesioned animals exhibited no reference memory deficit, whereas working memory abilities were seen significantly impaired, as compared with intact or sham-lesioned controls. Stereological analyses confirmed a dramatic noradrenergic neuron loss associated to reduced proliferation, but not survival or differentiation, of 5-bromo-2'deoxyuridine-positive progenitors in the dentate gyrus. Thus, ascending noradrenergic afferents may be involved in more complex aspects of cognitive performance (i.e., working memory) possibly via newly generated progenitors in the hippocampus. Copyright © 2016 Elsevier Inc. All rights reserved.

  8. P2X receptors, sensory neurons and pain.

    PubMed

    Bele, Tanja; Fabbretti, Elsa

    2015-01-01

    Pain represents a very large social and clinical problem since the current treatment provides insufficient pain relief. Plasticity of pain receptors together with sensitisation of sensory neurons, and the role of soluble mediators released from non-neuronal cells render difficult to understand the spatial and temporal scale of pain development, neuronal responses and disease progression. In pathological conditions, ATP is one of the most powerful mediators that activates P2X receptors that behave as sensitive ATP-detectors, such as neuronal P2X3 receptor subtypes and P2X4 and P2X7 receptors expressed on non-neuronal cells. Dissecting the molecular mechanisms occurring in sensory neurons and in accessory cells allows to design appropriate tissue- and cell- targeted approaches to treat chronic pain.

  9. Association between a functional polymorphism in the MAOA gene and sudden infant death syndrome.

    PubMed

    Klintschar, Michael; Heimbold, Christian

    2012-03-01

    Abnormalities in the serotonergic as well as the noradrenergic neuronal systems are believed to contribute to sudden infant death syndrome (SIDS). The X-chromosomal monoamine oxidase A (MAOA) gene is of importance for both systems and up to now no systematic study on a functional polymorphism in this gene has been performed in a sufficiently large group. We investigated a functional MAOA promoter length polymorphism in 156 white SIDS cases and 260 gender- and age-matched control subjects by using capillary electrophoresis and fluorescence dye labeled primers. The pooled low-expressing alleles *2 and *3 were more frequent in the 99 male SIDS cases than in 161 male control subjects (44.4% vs 25.5%). However, there were no differences in female cases. The frequency of low expression alleles varied significantly with the age at death and were significantly more frequent in children who died between an age of 46 and 154 days than at an older age (54.9% vs 22.6%). Our results indicate a relationship between SIDS and the MAOA genotype in boys via influencing serotonergic and noradrenergic neurons in the brainstem. This locus is the first X-chromosomal locus associated with SIDS. Our results support the theory that abnormalities in the brainstem contribute to a subset of SIDS, at least in boys. Moreover, we argue that not only the serotonergic system but also other neuronal systems, among those the noradrenergic one, are involved.

  10. Initiating or blocking locomotion in spinal cats by applying noradrenergic drugs to restricted lumbar spinal segments.

    PubMed

    Marcoux, J; Rossignol, S

    2000-11-15

    After an acute low thoracic spinal transection (T13), cats can be made to walk with the hindlimbs on a treadmill with clonidine, an alpha2-noradrenergic agonist. Because previous studies of neonatal rat spinal cord in vitro suggest that the most important lumbar segments for rhythmogenesis are L1-L2, we investigated the role of various lumbar segments in the initiation of walking movements on a treadmill of adult cats spinalized (T13), 5-6 d earlier. The locomotor activities were evaluated from electromyographic and video recordings. The results show that: (1) localized topical application of clonidine in restricted baths over either the L3-L4 or the L5-L7 segments was sufficient to induce walking movements. Yohimbine, an alpha2-noradrenergic antagonist, could block this locomotion when applied over L3-L4 or L5-L7; (2) microinjections of clonidine in one or two lumbar segments from L3 to L5 could also induce locomotion; (3) after an intravenous injection of clonidine, locomotion was blocked by microinjections of yohimbine in segments L3, L4, or L5 but not if the injection was in L6; (4) locomotion was also blocked in all cases by additional spinal transections at L3 or L4. These results show that it is possible to initiate walking in the adult spinal cat with a pharmacological stimulation of a restricted number of lumbar segments and also that the integrity of the L3-L4 segments is necessary to sustain the locomotor activity.

  11. MND2: A new mouse model of inherited motor neuron disease

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jones, J.M.; Albin, R.L.; Feldman, E.L.

    1993-06-01

    The autosomal recessive mutation mnd2 results in early onset motor neuron disease with rapidly progressive paralysis, severe muscle wasting, regression of thymus and spleen, and death before 40 days of age. mnd2 has been mapped to mouse chromosome 6 with the gene order: centromere-Tcrb-Ly-2-Sftp-3-D6Mit4-mnd2-D6Mit6, D6Mit9-D6Rck132-Raf-1, D6Mit11-D6Mit12-D6Mit14. mnd2 is located within a conserved linkage group with homologs on human chromosome 2p12-p13. Spinal motor neurons of homozygous affected animals are swollen and stain weakly, and electromyography revealed spontaneous activity characteristic of muscle denervation. Myelin staining was normal throughout the neuraxis. The clinical observations are consistent with a primary abnormality of lower motormore » neuron function. This new animal model will be of value for identification of a genetic defect responsible for motor neuron disease and for evaluation of new therapies. 36 refs., 7 figs., 2 tabs.« less

  12. The Medial Paralemniscal Nucleus and Its Afferent Neuronal Connections in Rat

    PubMed Central

    VARGA, TAMÁS; PALKOVITS, MIKLÓS; USDIN, TED BJÖRN; DOBOLYI, ARPÁD

    2009-01-01

    Previously, we described a cell group expressing tuberoinfundibular peptide of 39 residues (TIP39) in the lateral pontomesencephalic tegmentum, and referred to it as the medial paralemniscal nucleus (MPL). To identify this nucleus further in rat, we have now characterized the MPL cytoarchitectonically on coronal, sagittal, and horizontal serial sections. Neurons in the MPL have a columnar arrangement distinct from adjacent areas. The MPL is bordered by the intermediate nucleus of the lateral lemniscus nucleus laterally, the oral pontine reticular formation medially, and the rubrospinal tract ventrally, whereas the A7 noradrenergic cell group is located immediately mediocaudal to the MPL. TIP39-immunoreactive neurons are distributed throughout the cytoarchitectonically defined MPL and constitute 75% of its neurons as assessed by double labeling of TIP39 with a fluorescent Nissl dye or NeuN. Furthermore, we investigated the neuronal inputs to the MPL by using the retrograde tracer cholera toxin B subunit. The MPL has afferent neuronal connections distinct from adjacent brain regions including major inputs from the auditory cortex, medial part of the medial geniculate body, superior colliculus, external and dorsal cortices of the inferior colliculus, periolivary area, lateral preoptic area, hypothalamic ventromedial nucleus, lateral and dorsal hypothalamic areas, subparafascicular and posterior intralaminar thalamic nuclei, periaqueductal gray, and cuneiform nucleus. In addition, injection of the anterograde tracer biotinylated dextran amine into the auditory cortex and the hypothalamic ventromedial nucleus confirmed projections from these areas to the distinct MPL. The afferent neuronal connections of the MPL suggest its involvement in auditory and reproductive functions. PMID:18770870

  13. The medial paralemniscal nucleus and its afferent neuronal connections in rat.

    PubMed

    Varga, Tamás; Palkovits, Miklós; Usdin, Ted Björn; Dobolyi, Arpád

    2008-11-10

    Previously, we described a cell group expressing tuberoinfundibular peptide of 39 residues (TIP39) in the lateral pontomesencephalic tegmentum, and referred to it as the medial paralemniscal nucleus (MPL). To identify this nucleus further in rat, we have now characterized the MPL cytoarchitectonically on coronal, sagittal, and horizontal serial sections. Neurons in the MPL have a columnar arrangement distinct from adjacent areas. The MPL is bordered by the intermediate nucleus of the lateral lemniscus nucleus laterally, the oral pontine reticular formation medially, and the rubrospinal tract ventrally, whereas the A7 noradrenergic cell group is located immediately mediocaudal to the MPL. TIP39-immunoreactive neurons are distributed throughout the cytoarchitectonically defined MPL and constitute 75% of its neurons as assessed by double labeling of TIP39 with a fluorescent Nissl dye or NeuN. Furthermore, we investigated the neuronal inputs to the MPL by using the retrograde tracer cholera toxin B subunit. The MPL has afferent neuronal connections distinct from adjacent brain regions including major inputs from the auditory cortex, medial part of the medial geniculate body, superior colliculus, external and dorsal cortices of the inferior colliculus, periolivary area, lateral preoptic area, hypothalamic ventromedial nucleus, lateral and dorsal hypothalamic areas, subparafascicular and posterior intralaminar thalamic nuclei, periaqueductal gray, and cuneiform nucleus. In addition, injection of the anterograde tracer biotinylated dextran amine into the auditory cortex and the hypothalamic ventromedial nucleus confirmed projections from these areas to the distinct MPL. The afferent neuronal connections of the MPL suggest its involvement in auditory and reproductive functions. (c) 2008 Wiley-Liss, Inc.

  14. Adrenergic receptors inhibit TRPV1 activity in the dorsal root ganglion neurons of rats.

    PubMed

    Matsushita, Yumi; Manabe, Miki; Kitamura, Naoki; Shibuya, Izumi

    2018-01-01

    Transient receptor potential vanilloid type 1 (TRPV1) is a polymodal receptor channel that responds to multiple types of stimuli, such as heat, acid, mechanical pressure and some vanilloids. Capsaicin is the most commonly used vanilloid to stimulate TRPV1. TRPV1 channels are expressed in dorsal root ganglion neurons that extend to Aδ- and C-fibers and have a role in the transduction of noxious inputs to the skin into the electrical signals of the sensory nerve. Although noradrenergic nervous systems, including the descending antinociceptive system and the sympathetic nervous system, are known to modulate pain sensation, the functional association between TRPV1 and noradrenaline in primary sensory neurons has rarely been examined. In the present study, we examined the effects of noradrenaline on capsaicin-evoked currents in cultured dorsal root ganglion neurons of the rat by the whole-cell voltage clamp method. Noradrenaline at concentrations higher than 0.1 pM significantly reduced the amplitudes of the inward capsaicin currents recorded at -60 mV holding potential. This inhibitory action was reversed by either yohimbine (an α2 antagonist, 10 nM) or propranolol (a β antagonist, 10 nM). The α2 agonists, clonidine (1 pM) and dexmedetomidine (1 pM) inhibited capsaicin currents, and yohimbine (1 nM) reversed the effects of clonidine. The inhibitory action of noradrenaline was not seen in the neurons pretreated with pertussis toxin (100 μg/ml for 24 h) and the neurons dialyzed intracellularly with guanosine 5'- [β-thio] diphosphate (GDPβS, 200 μM), the catalytic subunit of protein kinase A (250 U/ml) or okadaic acid (1 μM). These results suggest that noradrenaline directly acts on dorsal root ganglion neurons to inhibit the activity of TRPV1 depending on the activation of α2-adrenoceptors followed by the inhibition of the adenylate cyclase/cAMP/protein kinase A pathway.

  15. Entry of Botulinum Neurotoxin Subtypes A1 and A2 into Neurons

    PubMed Central

    Kroken, Abby R.; Blum, Faith C.; Zuverink, Madison

    2016-01-01

    ABSTRACT Botulinum neurotoxins (BoNTs) are the most toxic proteins for humans but also are common therapies for neurological diseases. BoNTs are dichain toxins, comprising an N-terminal catalytic domain (LC) disulfide bond linked to a C-terminal heavy chain (HC) which includes a translocation domain (HN) and a receptor binding domain (HC). Recently, the BoNT serotype A (BoNT/A) subtypes A1 and A2 were reported to possess similar potencies but different rates of cellular intoxication and pathology in a mouse model of botulism. The current study measured HCA1 and HCA2 entry into rat primary neurons and cultured Neuro2A cells. We found that there were two sequential steps during the association of BoNT/A with neurons. The initial step was ganglioside dependent, while the subsequent step involved association with synaptic vesicles. HCA1 and HCA2 entered the same population of synaptic vesicles and entered cells at similar rates. The primary difference was that HCA2 had a higher degree of receptor occupancy for cells and neurons than HcA1. Thus, HCA2 and HCA1 share receptors and entry pathway but differ in their affinity for receptor. The initial interaction of HCA1 and HCA2 with neurons may contribute to the unique pathologies of BoNT/A1 and BoNT/A2 in mouse models. PMID:27795365

  16. Conditional Depletion of Hippocampal Brain-Derived Neurotrophic Factor Exacerbates Neuropathology in a Mouse Model of Alzheimer’s Disease

    PubMed Central

    Braun, David J.; Kalinin, Sergey

    2017-01-01

    Damage occurring to noradrenergic neurons in the locus coeruleus (LC) contributes to the evolution of neuroinflammation and neurodegeneration in a variety of conditions and diseases. One cause of LC damage may be loss of neurotrophic support from LC target regions. We tested this hypothesis by conditional unilateral knockout of brain-derived neurotrophic factor (BDNF) in adult mice. To evaluate the consequences of BDNF loss in the context of neurodegeneration, the mice harbored familial mutations for human amyloid precursor protein and presenilin-1. In these mice, BDNF depletion reduced tyrosine hydroxylase staining, a marker of noradrenergic neurons, in the rostral LC. BDNF depletion also reduced noradrenergic innervation in the hippocampus, the frontal cortex, and molecular layer of the cerebellum, assessed by staining for dopamine beta hydroxylase. BDNF depletion led to an increase in cortical amyloid plaque numbers and size but was without effect on plaque numbers in the striatum, a site with minimal innervation from the LC. Interestingly, cortical Iba1 staining for microglia was reduced by BDNF depletion and was correlated with reduced dopamine beta hydroxylase staining. These data demonstrate that reduction of BDNF levels in an LC target region can cause retrograde damage to LC neurons, leading to exacerbation of neuropathology in distinct LC target areas. Methods to reduce BDNF loss or supplement BDNF levels may be of value to reduce neurodegenerative processes normally limited by LC noradrenergic activities. PMID:28266222

  17. Noradrenergic mechanisms of arousal's bidirectional effects on episodic memory.

    PubMed

    Clewett, David; Sakaki, Michiko; Nielsen, Shawn; Petzinger, Giselle; Mather, Mara

    2017-01-01

    Arousal's selective effects on cognition go beyond the simple enhancement of emotional stimuli, sometimes enhancing and other times impairing processing of proximal neutral information. Past work shows that arousal impairs encoding of subsequent neutral stimuli regardless of their top-down priority via the engagement of β-adrenoreceptors. In contrast, retrograde amnesia induced by emotional arousal can flip to enhancement when preceding neutral items are prioritized in top-down attention. Whether β-adrenoreceptors also contribute to this retrograde memory enhancement of goal-relevant neutral stimuli is unclear. In this pharmacological study, we administered 40mg of propranolol or 40mg of placebo to healthy young adults to examine whether emotional arousal's bidirectional effects on declarative memory relies on β-adrenoreceptor activation. Following pill intake, participants completed an emotional oddball task in which they were asked to prioritize a neutral object appearing just before an emotional or neutral oddball image within a sequence of 7 neutral objects. Under placebo, emotional oddballs impaired memory for lower priority oddball+1 objects but had no effect on memory for high priority oddball-1 objects. Propranolol blocked this anterograde amnesic effect of arousal. Emotional oddballs also enhanced selective memory trade-offs significantly more in the placebo than drug condition, such that high priority oddball-1 objects were more likely to be remembered at the cost of their corresponding lower priority oddball+1 objects under arousal. Lastly, those who recalled more high priority oddball-1 objects preceding an emotional versus neutral oddball image showed greater increases in salivary alpha-amylase, a biomarker of noradrenergic system activation, across the task. Together these findings suggest that different noradrenergic mechanisms contribute to the anterograde and retrograde mnemonic effects of arousal on proximal neutral memoranda. Copyright © 2016

  18. Noradrenergic activation of the basolateral amygdala maintains hippocampus-dependent accuracy of remote memory

    PubMed Central

    Atucha, Erika; Vukojevic, Vanja; Fornari, Raquel V.; Ronzoni, Giacomo; Demougin, Philippe; Peter, Fabian; Atsak, Piray; Coolen, Marcel W.; Papassotiropoulos, Andreas; McGaugh, James L.; de Quervain, Dominique J.-F.; Roozendaal, Benno

    2017-01-01

    Emotional enhancement of memory by noradrenergic mechanisms is well-described, but the long-term consequences of such enhancement are poorly understood. Over time, memory traces are thought to undergo a neural reorganization, that is, a systems consolidation, during which they are, at least partly, transferred from the hippocampus to neocortical networks. This transfer is accompanied by a decrease in episodic detailedness. Here we investigated whether norepinephrine (NE) administration into the basolateral amygdala after training on an inhibitory avoidance discrimination task, comprising two distinct training contexts, alters systems consolidation dynamics to maintain episodic-like accuracy and hippocampus dependency of remote memory. At a 2-d retention test, both saline- and NE-treated rats accurately discriminated the training context in which they had received footshock. Hippocampal inactivation with muscimol before retention testing disrupted discrimination of the shock context in both treatment groups. At 28 d, saline-treated rats showed hippocampus-independent retrieval and lack of discrimination. In contrast, NE-treated rats continued to display accurate memory of the shock–context association. Hippocampal inactivation at this remote retention test blocked episodic-like accuracy and induced a general memory impairment. These findings suggest that the NE treatment altered systems consolidation dynamics by maintaining hippocampal involvement in the memory. This shift in systems consolidation was paralleled by time-regulated DNA methylation and transcriptional changes of memory-related genes, namely Reln and Pkmζ, in the hippocampus and neocortex. The findings provide evidence suggesting that consolidation of emotional memories by noradrenergic mechanisms alters systems consolidation dynamics and, as a consequence, influences the maintenance of long-term episodic-like accuracy of memory. PMID:28790188

  19. Noradrenergic activation of the basolateral amygdala maintains hippocampus-dependent accuracy of remote memory.

    PubMed

    Atucha, Erika; Vukojevic, Vanja; Fornari, Raquel V; Ronzoni, Giacomo; Demougin, Philippe; Peter, Fabian; Atsak, Piray; Coolen, Marcel W; Papassotiropoulos, Andreas; McGaugh, James L; de Quervain, Dominique J-F; Roozendaal, Benno

    2017-08-22

    Emotional enhancement of memory by noradrenergic mechanisms is well-described, but the long-term consequences of such enhancement are poorly understood. Over time, memory traces are thought to undergo a neural reorganization, that is, a systems consolidation, during which they are, at least partly, transferred from the hippocampus to neocortical networks. This transfer is accompanied by a decrease in episodic detailedness. Here we investigated whether norepinephrine (NE) administration into the basolateral amygdala after training on an inhibitory avoidance discrimination task, comprising two distinct training contexts, alters systems consolidation dynamics to maintain episodic-like accuracy and hippocampus dependency of remote memory. At a 2-d retention test, both saline- and NE-treated rats accurately discriminated the training context in which they had received footshock. Hippocampal inactivation with muscimol before retention testing disrupted discrimination of the shock context in both treatment groups. At 28 d, saline-treated rats showed hippocampus-independent retrieval and lack of discrimination. In contrast, NE-treated rats continued to display accurate memory of the shock-context association. Hippocampal inactivation at this remote retention test blocked episodic-like accuracy and induced a general memory impairment. These findings suggest that the NE treatment altered systems consolidation dynamics by maintaining hippocampal involvement in the memory. This shift in systems consolidation was paralleled by time-regulated DNA methylation and transcriptional changes of memory-related genes, namely Reln and Pkm ζ, in the hippocampus and neocortex. The findings provide evidence suggesting that consolidation of emotional memories by noradrenergic mechanisms alters systems consolidation dynamics and, as a consequence, influences the maintenance of long-term episodic-like accuracy of memory.

  20. Altered neuronal network and rescue in a human MECP2 duplication model

    PubMed Central

    Nageshappa, Savitha; Carromeu, Cassiano; Trujillo, Cleber A.; Mesci, Pinar; Espuny-Camacho, Ira; Pasciuto, Emanuela; Vanderhaeghen, Pierre; Verfaillie, Catherine; Raitano, Susanna; Kumar, Anujith; Carvalho, Claudia M.B.; Bagni, Claudia; Ramocki, Melissa B.; Araujo, Bruno H. S.; Torres, Laila B.; Lupski, James R.; Van Esch, Hilde; Muotri, Alysson R.

    2015-01-01

    Increased dosage of MeCP2 results in a dramatic neurodevelopmental phenotype with onset at birth. We generated induced pluripotent stem cells (iPSC) from patients with the MECP2 duplication syndrome (MECP2dup), carrying different duplication sizes, to study the impact of increased MeCP2 dosage in human neurons. We show that cortical neurons derived from these different MECP2dup iPSC lines have increase synaptogenesis and dendritic complexity. Additionally, using multi-electrodes arrays, we show that neuronal network synchronization was altered in MECP2dup-derived neurons. Given MeCP2 function at the epigenetic level, we tested if these alterations were reversible using a library of compounds with defined activity on epigenetic pathways. One histone deacetylase inhibitor, NCH-51, was validated as a potential clinical candidate. Interestingly, this compound has never been considered before as a therapeutic alternative for neurological disorders. Our model recapitulates early stages of the human MECP2 duplication syndrome and represents a promising cellular tool to facilitate therapeutic drug screening for severe neurodevelopmental disorders. PMID:26347316

  1. Entry of Botulinum Neurotoxin Subtypes A1 and A2 into Neurons.

    PubMed

    Kroken, Abby R; Blum, Faith C; Zuverink, Madison; Barbieri, Joseph T

    2017-01-01

    Botulinum neurotoxins (BoNTs) are the most toxic proteins for humans but also are common therapies for neurological diseases. BoNTs are dichain toxins, comprising an N-terminal catalytic domain (LC) disulfide bond linked to a C-terminal heavy chain (HC) which includes a translocation domain (H N ) and a receptor binding domain (H C ). Recently, the BoNT serotype A (BoNT/A) subtypes A1 and A2 were reported to possess similar potencies but different rates of cellular intoxication and pathology in a mouse model of botulism. The current study measured H C A1 and H C A2 entry into rat primary neurons and cultured Neuro2A cells. We found that there were two sequential steps during the association of BoNT/A with neurons. The initial step was ganglioside dependent, while the subsequent step involved association with synaptic vesicles. H C A1 and H C A2 entered the same population of synaptic vesicles and entered cells at similar rates. The primary difference was that H C A2 had a higher degree of receptor occupancy for cells and neurons than HcA1. Thus, H C A2 and H C A1 share receptors and entry pathway but differ in their affinity for receptor. The initial interaction of H C A1 and H C A2 with neurons may contribute to the unique pathologies of BoNT/A1 and BoNT/A2 in mouse models. Copyright © 2016 American Society for Microbiology.

  2. Peripheral markers of serotonergic and noradrenergic function in post-pubertal, caucasian males with autistic disorder.

    PubMed

    Croonenberghs, J; Delmeire, L; Verkerk, R; Lin, A H; Meskal, A; Neels, H; Van der Planken, M; Scharpe, S; Deboutte, D; Pison, G; Maes, M

    2000-03-01

    Some studies have suggested that disorders in the peripheral and central metabolism of serotonin (5-HT) and noradrenaline may play a role in the pathophysiology of autistic disorder. This study examines serotonergic and noradrenergic markers in a study group of 13 male, post-pubertal, caucasian autistic patients (age 12-18 y; I.Q. > 55) and 13 matched volunteers. [3H]-paroxetine binding Kd values were significantly higher in patients with autism than in healthy volunteers. Plasma concentrations of tryptophan, the precursor of 5-HT, were significantly lower in autistic patients than in healthy volunteers. There were no significant differences between autistic and normal children in the serum concentrations of 5-HT, or the 24-hr urinary excretion of 5-hydroxy-indoleacetic acid (5-HIAA), adrenaline, noradrenaline, and dopamine. There were no significant differences in [3H]-rauwolscine binding Bmax or Kd values, or in the serum concentrations of tyrosine, the precursor of noradrenaline, between both study groups. There were highly significant positive correlations between age and 24-hr urinary excretion of 5-HIAA and serum tryptophan. The results suggest that: 1) serotonergic disturbances, such as defects in the 5-HT transporter system and lowered plasma tryptophan, may play a role in the pathophysiology of autism; 2) autism is not associated with alterations in the noradrenergic system; and 3) the metabolism of serotonin in humans undergoes significant changes between the ages of 12 and 18 years.

  3. Ilex paraguariensis Promotes Orofacial Pain Relief After Formalin Injection: Involvement of Noradrenergic Pathway.

    PubMed

    de Carvalho, Eudislaine Fonseca; de Oliveira, Simone Kobe; Nardi, Viviane Koepp; Gelinski, Tathiana Carla; Bortoluzzi, Marcelo Carlos; Maraschin, Marcelo; Nardi, Geisson Marcos

    2016-03-01

    Drinking mate or chimarrão, a hot infusion of Ilex paraguariensis (ILEX) leaves, is a common habit in Southern South America that has a social and almost ritualistic role. It has been used as a stimulant beverage in South America and analgesic in regions of Argentina for treatment of headache and others painful inflammatory conditions such as arthritis and rheumatism. The aim of this study was to evaluate the pharmacological activity of I. paraguariensis infusion (ILEX) on orofacial nociception model induced by formalin, and study its mechanism of action. The analgesic effect of ILEX was assessed through writhing test, paw formalin test, paw edema induced by carrageenan, and orofacial pain induced by formalin. To study the action mechanism of ILEX, opioidergic, dopaminergic, nitrergic, and adrenergic pathways were investigated. The high-performance liquid chromatography analysis of ILEX infusion revealed caffeine and theobromine. The treatment with ILEX reduced the number of writhing. However, it was effective neither in the formalin paw test nor in the paw edema induced by carrageenan. Different from formalin paw test, ILEX was able to reduce the orofacial reactivity to formalin in 31.8% (70.4 ± 2.5 s; first phase), and 20% (127.3 ± 18.9 s; second phase). The analgesic effect of ILEX results from the modulation of noradrenergic pathways since prazosin (α1-adrenoceptor antagonist, 0.15 mg/kg; intraperitoneal) reversed the analgesic effect of ILEX. The present report demonstrates that analgesic effect of ILEX in orofacial formalin test is due mainly to modulation of noradrenergic pathways. Ilex paraguariensis (ILEX) has been used as a stimulant beverage in South America and analgesic in regions of Argentina for the treatment of headache and others painful inflammatory conditions such arthritis and rheumatism.The aim of this study was to evaluate the pharmacological activity of ILEX on orofacial nociception model induced by formalin, and study its mechanism of

  4. Synaptic communication between neurons and NG2+ cells.

    PubMed

    Paukert, Martin; Bergles, Dwight E

    2006-10-01

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

  5. Stimulation of feeding by three different glucose-sensing mechanisms requires hindbrain catecholamine neurons.

    PubMed

    Li, Ai-Jun; Wang, Qing; Dinh, Thu T; Powers, Bethany R; Ritter, Sue

    2014-02-15

    Previous work has shown that hindbrain catecholamine neurons are required components of the brain's glucoregulatory circuitry. However, the mechanisms and circuitry underlying their glucoregulatory functions are poorly understood. Here we examined three drugs, glucosamine (GcA), phloridzin (Phl) and 5-thio-d-glucose (5TG), that stimulate food intake but interfere in different ways with cellular glucose utilization or transport. We examined feeding and blood glucose responses to each drug in male rats previously injected into the hypothalamic paraventricular nucleus with anti-dopamine-β-hydroxylase conjugated to saporin (DSAP), a retrogradely transported immunotoxin that selectively lesions noradrenergic and adrenergic neurons, or with unconjugated saporin (SAP) control. Our major findings were 1) that GcA, Phl, and 5TG all stimulated feeding in SAP controls whether injected into the lateral or fourth ventricle (LV or 4V), 2) that each drug's potency was similar for both LV and 4V injections, 3) that neither LV or 4V injection of these drugs evoked feeding in DSAP-lesioned rats, and 4) that only 5TG, which blocks glycolysis, stimulated a blood glucose response. The antagonist of the MEK/ERK signaling cascade, U0126, attenuated GcA-induced feeding, but not Phl- or 5TG-induced feeding. Thus GcA, Phl, and 5TG, although differing in mechanism and possibly activating different neural populations, stimulate feeding in a catecholamine-dependent manner. Although results do not exclude the possibility that catecholamine neurons possess glucose-sensing mechanisms responsive to all of these agents, currently available evidence favors the possibility that the feeding effects result from convergent neural circuits in which catecholamine neurons are a required component.

  6. Stimulation of feeding by three different glucose-sensing mechanisms requires hindbrain catecholamine neurons

    PubMed Central

    Wang, Qing; Dinh, Thu T.; Powers, Bethany R.; Ritter, Sue

    2013-01-01

    Previous work has shown that hindbrain catecholamine neurons are required components of the brain's glucoregulatory circuitry. However, the mechanisms and circuitry underlying their glucoregulatory functions are poorly understood. Here we examined three drugs, glucosamine (GcA), phloridzin (Phl) and 5-thio-d-glucose (5TG), that stimulate food intake but interfere in different ways with cellular glucose utilization or transport. We examined feeding and blood glucose responses to each drug in male rats previously injected into the hypothalamic paraventricular nucleus with anti-dopamine-β-hydroxylase conjugated to saporin (DSAP), a retrogradely transported immunotoxin that selectively lesions noradrenergic and adrenergic neurons, or with unconjugated saporin (SAP) control. Our major findings were 1) that GcA, Phl, and 5TG all stimulated feeding in SAP controls whether injected into the lateral or fourth ventricle (LV or 4V), 2) that each drug's potency was similar for both LV and 4V injections, 3) that neither LV or 4V injection of these drugs evoked feeding in DSAP-lesioned rats, and 4) that only 5TG, which blocks glycolysis, stimulated a blood glucose response. The antagonist of the MEK/ERK signaling cascade, U0126, attenuated GcA-induced feeding, but not Phl- or 5TG-induced feeding. Thus GcA, Phl, and 5TG, although differing in mechanism and possibly activating different neural populations, stimulate feeding in a catecholamine-dependent manner. Although results do not exclude the possibility that catecholamine neurons possess glucose-sensing mechanisms responsive to all of these agents, currently available evidence favors the possibility that the feeding effects result from convergent neural circuits in which catecholamine neurons are a required component. PMID:24381177

  7. Reduced Slc6a15 in Nucleus Accumbens D2-Neurons Underlies Stress Susceptibility

    PubMed Central

    Nam, Hyungwoo; Engeln, Michel; Konkalmatt, Prasad; Iniguez, Sergio D.

    2017-01-01

    Previous research demonstrates that Slc6a15, a neutral amino acid transporter, is associated with depression susceptibility. However, no study examined Slc6a15 in the ventral striatum [nucleus accumbens (NAc)] in depression. Given our previous characterization of Slc6a15 as a striatal dopamine receptor 2 (D2)-neuron-enriched gene, we examined the role of Slc6a15 in NAc D2-neurons in mediating susceptibility to stress in male mice. First, we showed that Slc6a15 mRNA was reduced in NAc of mice susceptible to chronic social defeat stress (CSDS), a paradigm that produces behavioral and molecular adaptations that resemble clinical depression. Consistent with our preclinical data, we observed Slc6a15 mRNA reduction in NAc of individuals with major depressive disorder (MDD). The Slc6a15 reduction in NAc occurred selectively in D2-neurons. Next, we used Cre-inducible viruses combined with D2-Cre mice to reduce or overexpress Slc6a15 in NAc D2-neurons. Slc6a15 reduction in D2-neurons caused enhanced susceptibility to a subthreshold social defeat stress (SSDS) as observed by reduced social interaction, while a reduction in social interaction following CSDS was not observed when Slc6a15 expression in D2-neurons was restored. Finally, since both D2-medium spiny neurons (MSNs) and D2-expressing choline acetyltransferase (ChAT) interneurons express Slc6a15, we examined Slc6a15 protein in these interneurons after CSDS. Slc6a15 protein was unaltered in ChAT interneurons. Consistent with this, reducing Slc5a15 selectively in NAc D2-MSNs, using A2A-Cre mice that express Cre selectively in D2-MSNs, caused enhanced susceptibility to SSDS. Collectively, our data demonstrate that reduced Slc6a15 in NAc occurs in MDD individuals and that Slc6a15 reduction in NAc D2-neurons underlies stress susceptibility. SIGNIFICANCE STATEMENT Our study demonstrates a role for reduced Slc6a15, a neutral amino acid transporter, in nucleus accumbens (NAc) in depression and stress susceptibility. The

  8. Chronic alcohol exposure differentially affects activation of female locus coeruleus neurons and the subcellular distribution of corticotropin releasing factor receptors.

    PubMed

    Retson, T A; Reyes, B A; Van Bockstaele, E J

    2015-01-02

    Understanding the neurobiological bases for sex differences in alcohol dependence is needed to help guide the development of individualized therapies for alcohol abuse disorders. In the present study, alcohol-induced adaptations in (1) anxiety-like behavior, (2) patterns of c-Fos activation and (3) subcellular distribution of corticotropin releasing factor receptor in locus coeruleus (LC) neurons was investigated in male and female Sprague-Dawley rats that were chronically exposed to ethanol using a liquid diet. Results confirm and extend reports by others showing that chronic ethanol exposure produces an anxiogenic-like response in both male and female subjects. Ethanol-induced sex differences were observed with increased c-Fos expression in LC neurons of female ethanol-treated subjects compared to controls or male subjects. Results also reveal sex differences in the subcellular distribution of the CRFr in LC-noradrenergic neurons with female subjects exposed to ethanol exhibiting a higher frequency of plasmalemmal CRFrs. These adaptations have implications for LC neuronal activity and its neural targets across the sexes. Considering the important role of the LC in ethanol-induced activation of the hypothalamo-pituitary-adrenal (HPA) axis, the present results indicate important sex differences in feed-forward regulation of the HPA axis that may render alcohol dependent females more vulnerable to subsequent stress exposure. Copyright © 2014 Elsevier Inc. All rights reserved.

  9. Role for VGLUT2 in selective vulnerability of midbrain dopamine neurons

    PubMed Central

    Steinkellner, Thomas; Farino, Zachary J.; Sonders, Mark S.; Villeneuve, Michael; Freyberg, Robin J.; Przedborski, Serge; Lu, Wei; Hnasko, Thomas S.

    2018-01-01

    Parkinson’s disease is characterized by the loss of dopamine (DA) neurons in the substantia nigra pars compacta (SNc). DA neurons in the ventral tegmental area are more resistant to this degeneration than those in the SNc, though the mechanisms for selective resistance or vulnerability remain poorly understood. A key to elucidating these processes may lie within the subset of DA neurons that corelease glutamate and express the vesicular glutamate transporter VGLUT2. Here, we addressed the potential relationship between VGLUT expression and DA neuronal vulnerability by overexpressing VGLUT in DA neurons of flies and mice. In Drosophila, VGLUT overexpression led to loss of select DA neuron populations. Similarly, expression of VGLUT2 specifically in murine SNc DA neurons led to neuronal loss and Parkinsonian behaviors. Other neuronal cell types showed no such sensitivity, suggesting that DA neurons are distinctively vulnerable to VGLUT2 expression. Additionally, most DA neurons expressed VGLUT2 during development, and coexpression of VGLUT2 with DA markers increased following injury in the adult. Finally, conditional deletion of VGLUT2 made DA neurons more susceptible to Parkinsonian neurotoxins. These data suggest that the balance of VGLUT2 expression is a crucial determinant of DA neuron survival. Ultimately, manipulation of this VGLUT2-dependent process may represent an avenue for therapeutic development. PMID:29337309

  10. 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. Copyright © 2012 IBRO. Published by Elsevier Ltd. All rights reserved.

  11. I(2)(PP2A) regulates p53 and Akt correlatively and leads the neurons to abort apoptosis.

    PubMed

    Liu, Gong-Ping; Wei, Wei; Zhou, Xin; Zhang, Yao; Shi, Hai-Hong; Yin, Jun; Yao, Xiu-Qing; Peng, Cai-Xia; Hu, Juan; Wang, Qun; Li, Hong-Lian; Wang, Jian-Zhi

    2012-02-01

    A chronic neuron loss is the cardinal pathology in Alzheimer disease (AD), but it is still not understood why most neurons in AD brain do not accomplish apoptosis even though they are actually exposed to an environment with enriched proapoptotic factors. Protein phosphatase-2A inhibitor-2 (I(2)(PP2A)), an endogenous PP2A inhibitor, is significantly increased in AD brain, but the role of I(2)(PP2A) in AD-like neuron loss is elusive. Here, we show that I(2)(PP2A) regulates p53 and Akt correlatively. The mechanisms involve activated transcription and p38 MAPK activities. More importantly, we demonstrate that the simultaneous activation of Akt induced by I(2)(PP2A) counteracts the hyperactivated p53-induced cell apoptosis. Furthermore, I(2)(PP2A), p53 and Akt are all elevated in the brain of mouse model and AD patients. Our results suggest that the increased I(2)(PP2A) may trigger apoptosis by p53 upregulation, but due to simultaneous activation of Akt, the neurons are aborted from the apoptotic pathway. This finding contributes to the understanding of why most neurons in AD brain do not undergo apoptosis. Copyright © 2010. Published by Elsevier Inc.

  12. Arousal amplifies biased competition between high and low priority memories more in women than in men: the role of elevated noradrenergic activity

    PubMed Central

    Clewett, David; Sakaki, Michiko; Huang, Ringo; Nielsen, Shawn E.; Mather, Mara

    2017-01-01

    Recent findings indicate that emotional arousal can enhance memory consolidation of goal-relevant stimuli while impairing it for irrelevant stimuli. According to one recent model, these goal-dependent memory tradeoffs are driven by arousal-induced release of norepinephrine (NE), which amplifies neural gain in target sensory and memory processing brain regions. Past work also shows that ovarian hormones modulate activity in the same regions thought to support NE’s effects on memory, such as the amygdala, suggesting that men and women may be differentially susceptible to arousal’s dual effects on episodic memory. Here, we aimed to determine the neurohormonal mechanisms that mediate arousal-biased competition processes in memory. In a competitive visuo-attention task, participants viewed images of a transparent object overlaid on a background scene and explicitly memorized one of these stimuli while ignoring the other. Participants then heard emotional or neutral audio-clips and provided a subjective arousal rating. Hierarchical generalized linear modeling (HGLM) analyses revealed that greater pre-to-post task increases in salivary alpha-amylase (sAA), a biomarker of noradrenergic activity, was associated with significantly greater arousal-enhanced memory tradeoffs in women than in men. These sex-dependent effects appeared to result from phasic and background noradrenergic activity interacting to suppress task-irrelevant representations in women but enhancing them in men. Additionally, in naturally cycling women, low ovarian hormone levels interacted with increased noradrenergic activity to amplify memory selectivity independently of emotion-induced arousal. Together these findings suggest that increased noradrenergic transmission enhances preferential consolidation of goal-relevant memory traces according to phasic arousal and ovarian hormone levels in women. PMID:28324703

  13. Arousal amplifies biased competition between high and low priority memories more in women than in men: The role of elevated noradrenergic activity.

    PubMed

    Clewett, David; Sakaki, Michiko; Huang, Ringo; Nielsen, Shawn E; Mather, Mara

    2017-06-01

    Recent findings indicate that emotional arousal can enhance memory consolidation of goal-relevant stimuli while impairing it for irrelevant stimuli. According to one recent model, these goal-dependent memory tradeoffs are driven by arousal-induced release of norepinephrine (NE), which amplifies neural gain in target sensory and memory processing brain regions. Past work also shows that ovarian hormones modulate activity in the same regions thought to support NE's effects on memory, such as the amygdala, suggesting that men and women may be differentially susceptible to arousal's dual effects on episodic memory. Here, we aimed to determine the neurohormonal mechanisms that mediate arousal-biased competition processes in memory. In a competitive visuo-attention task, participants viewed images of a transparent object overlaid on a background scene and explicitly memorized one of these stimuli while ignoring the other. Participants then heard emotional or neutral audio-clips and provided a subjective arousal rating. Hierarchical generalized linear modeling (HGLM) analyses revealed that greater pre-to-post task increases in salivary alpha-amylase (sAA), a biomarker of noradrenergic activity, was associated with significantly greater arousal-enhanced memory tradeoffs in women than in men. These sex-dependent effects appeared to result from phasic and background noradrenergic activity interacting to suppress task-irrelevant representations in women but enhancing them in men. Additionally, in naturally cycling women, low ovarian hormone levels interacted with increased noradrenergic activity to amplify memory selectivity independently of emotion-induced arousal. Together these findings suggest that increased noradrenergic transmission enhances preferential consolidation of goal-relevant memory traces according to phasic arousal and ovarian hormone levels in women. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Effects of chronic sleep fragmentation on wake-active neurons and the hypercapnic arousal response.

    PubMed

    Li, Yanpeng; Panossian, Lori A; Zhang, Jing; Zhu, Yan; Zhan, Guanxia; Chou, Yu-Ting; Fenik, Polina; Bhatnagar, Seema; Piel, David A; Beck, Sheryl G; Veasey, Sigrid

    2014-01-01

    Delayed hypercapnic arousals may occur in obstructive sleep apnea. The impaired arousal response is expected to promote more pronounced oxyhemoglobin desaturations. We hypothesized that long-term sleep fragmentation (SF) results in injury to or dysfunction of wake-active neurons that manifests, in part, as a delayed hypercapnic arousal response. Adult male mice were implanted for behavioral state recordings and randomly assigned to 4 weeks of either orbital platform SF (SF4wk, 30 events/h) or control conditions (Ct4wk) prior to behavioral, histological, and locus coeruleus (LC) whole cell electrophysiological evaluations. SF was successfully achieved across the 4 week study, as evidenced by a persistently increased arousal index, P < 0.01 and shortened sleep bouts, P < 0.05, while total sleep/wake times and plasma corticosterone levels were unaffected. A multiple sleep latency test performed at the onset of the dark period showed a reduced latency to sleep in SF4wk mice (P < 0.05). The hypercapnic arousal latency was increased, Ct4wk 64 ± 5 sec vs. SF4wk 154 ± 6 sec, P < 0.001, and remained elevated after a 2 week recovery (101 ± 4 sec, P < 0.001). C-fos activation in noradrenergic, orexinergic, histaminergic, and cholinergic wake-active neurons was reduced in response to hypercapnia (P < 0.05-0.001). Catecholaminergic and orexinergic projections into the cingulate cortex were also reduced in SF4wk (P < 0.01). In addition, SF4wk resulted in impaired LC neuron excitability (P < 0.01). Four weeks of sleep fragmentation (SF4wk) impairs arousal responses to hypercapnia, reduces wake neuron projections and locus coeruleus neuronal excitability, supporting the concepts that some effects of sleep fragmentation may contribute to impaired arousal responses in sleep apnea, which may not reverse immediately with therapy.

  15. Reduced Slc6a15 in Nucleus Accumbens D2-Neurons Underlies Stress Susceptibility.

    PubMed

    Chandra, Ramesh; Francis, T Chase; Nam, Hyungwoo; Riggs, Lace M; Engeln, Michel; Rudzinskas, Sarah; Konkalmatt, Prasad; Russo, Scott J; Turecki, Gustavo; Iniguez, Sergio D; Lobo, Mary Kay

    2017-07-05

    Previous research demonstrates that Slc6a15, a neutral amino acid transporter, is associated with depression susceptibility. However, no study examined Slc6a15 in the ventral striatum [nucleus accumbens (NAc)] in depression. Given our previous characterization of Slc6a15 as a striatal dopamine receptor 2 (D2)-neuron-enriched gene, we examined the role of Slc6a15 in NAc D2-neurons in mediating susceptibility to stress in male mice. First, we showed that Slc6a15 mRNA was reduced in NAc of mice susceptible to chronic social defeat stress (CSDS), a paradigm that produces behavioral and molecular adaptations that resemble clinical depression. Consistent with our preclinical data, we observed Slc6a15 mRNA reduction in NAc of individuals with major depressive disorder (MDD). The Slc6a15 reduction in NAc occurred selectively in D2-neurons. Next, we used Cre-inducible viruses combined with D2-Cre mice to reduce or overexpress Slc6a15 in NAc D2-neurons. Slc6a15 reduction in D2-neurons caused enhanced susceptibility to a subthreshold social defeat stress (SSDS) as observed by reduced social interaction, while a reduction in social interaction following CSDS was not observed when Slc6a15 expression in D2-neurons was restored. Finally, since both D2-medium spiny neurons (MSNs) and D2-expressing choline acetyltransferase (ChAT) interneurons express Slc6a15, we examined Slc6a15 protein in these interneurons after CSDS. Slc6a15 protein was unaltered in ChAT interneurons. Consistent with this, reducing Slc5a15 selectively in NAc D2-MSNs, using A2A-Cre mice that express Cre selectively in D2-MSNs, caused enhanced susceptibility to SSDS. Collectively, our data demonstrate that reduced Slc6a15 in NAc occurs in MDD individuals and that Slc6a15 reduction in NAc D2-neurons underlies stress susceptibility. SIGNIFICANCE STATEMENT Our study demonstrates a role for reduced Slc6a15, a neutral amino acid transporter, in nucleus accumbens (NAc) in depression and stress susceptibility. The

  16. Intermittent Short Sleep Results in Lasting Sleep Wake Disturbances and Degeneration of Locus Coeruleus and Orexinergic Neurons.

    PubMed

    Zhu, Yan; Fenik, Polina; Zhan, Guanxia; Somach, Rebecca; Xin, Ryan; Veasey, Sigrid

    2016-08-01

    Intermittent short sleep (ISS) is pervasive among students and workers in modern societies, yet the lasting consequences of repeated short sleep on behavior and brain health are largely unexplored. Wake-activated neurons may be at increased risk of metabolic injury across sustained wakefulness. To examine the effects of ISS on wake-activated neurons and wake behavior, wild-type mice were randomized to ISS (a repeated pattern of short sleep on 3 consecutive days followed by 4 days of recovery sleep for 4 weeks) or rested control conditions. Subsets of both groups were allowed a recovery period consisting of 4-week unperturbed activity in home cages with littermates. Mice were examined for immediate and delayed (following recovery) effects of ISS on wake neuron cell metabolics, cell counts, and sleep/wake patterns. ISS resulted in sustained disruption of sleep/wake activity, with increased wakefulness during the lights-on period and reduced wake bout duration and wake time during the lights-off period. Noradrenergic locus coeruleus (LC) and orexinergic neurons showed persistent alterations in morphology, and reductions in both neuronal stereological cell counts and fronto-cortical projections. Surviving wake-activated neurons evidenced persistent reductions in sirtuins 1 and 3 and increased lipofuscin. In contrast, ISS resulted in no lasting injury to the sleep-activated melanin concentrating hormone neurons. Collectively these findings demonstrate for the first time that ISS imparts significant lasting disturbances in sleep/wake activity, degeneration of wake-activated LC and orexinergic neurons, and lasting metabolic changes in remaining neurons most consistent with premature senescence. © 2016 Associated Professional Sleep Societies, LLC.

  17. REM Sleep–like Atonia of Hypoglossal (XII) Motoneurons Is Caused by Loss of Noradrenergic and Serotonergic Inputs

    PubMed Central

    Fenik, Victor B.; Davies, Richard O.; Kubin, Leszek

    2017-01-01

    Rationale Studies of hypoglossal (XII) motoneurons that innervate the genioglossus muscle, an upper airway dilator, suggested that the suppression of upper airway motor tone during REM sleep is caused by withdrawal of excitation mediated by norepinephrine and serotonin. Objectives Our objectives were to determine whether antagonism of aminergic receptors located in the XII nucleus region can abolish the REM sleep–like atonia of XII motoneurons, and whether both serotonergic and noradrenergic antagonists are required to achieve this effect. Methods REM sleep–like episodes were elicited in anesthetized rats by pontine carbachol injections before and at various times after microinjection of prazosin and methysergide combined, or of only one of the drugs, into the XII nucleus. Measurements and Main Results Spontaneous XII nerve activity was significantly reduced, by 35 to 81%, by each antagonist alone and in combination, indicating that XII motoneurons were under both noradrenergic and serotonergic endogenous excitatory drives. During the 32 to 81 min after microinjections of both antagonists, pontine carbachol caused no depression of XII nerve activity, whereas other characteristic effects (activation of the hippocampal and cortical EEG, and slowing of the respiratory rate) remained intact. A partial recovery of the depressant effect of carbachol then occurred parallel to the recovery of spontaneous XII nerve activity from the depressant effect of the antagonists. Microinjections of either antagonist alone did not eliminate the depressant effect of carbachol. Conclusions The REM sleep–like depression of XII motoneuronal activity induced by pontine carbachol can be fully accounted for by the combined withdrawal of noradrenergic and serotonergic effects on XII motoneurons. PMID:16100007

  18. Soman increases neuronal COX-2 levels: possible link between seizures and protracted neuronal damage.

    PubMed

    Angoa-Pérez, Mariana; Kreipke, Christian W; Thomas, David M; Van Shura, Kerry E; Lyman, Megan; McDonough, John H; Kuhn, Donald M

    2010-12-01

    Nerve agent-induced seizures cause neuronal damage in brain limbic and cortical circuits leading to persistent behavioral and cognitive deficits. Without aggressive anticholinergic and benzodiazepine therapy, seizures can be prolonged and neuronal damage progresses for extended periods of time. The objective of this study was to determine the effects of the nerve agent soman on expression of cyclooxygenase-2 (COX-2), the initial enzyme in the biosynthetic pathway of the proinflammatory prostaglandins and a factor that has been implicated in seizure initiation and propagation. Rats were exposed to a toxic dose of soman and scored behaviorally for seizure intensity. Expression of COX-2 was determined throughout brain from 4h to 7 days after exposure by immunohistochemistry and immunoblotting. Microglial activation and astrogliosis were assessed microscopically over the same time-course. Soman increased COX-2 expression in brain regions known to be damaged by nerve agents (e.g., hippocampus, amygdala, piriform cortex and thalamus). COX-2 expression was induced in neurons, and not in microglia or astrocytes, and remained elevated through 7 days. The magnitude of COX-2 induction was correlated with seizure intensity. COX-1 expression was not changed by soman. Increased expression of neuronal COX-2 by soman is a late-developing response relative to other signs of acute physiological distress caused by nerve agents. COX-2-mediated production of prostaglandins is a consequence of the seizure-induced neuronal damage, even after survival of the initial cholinergic crisis is assured. COX-2 inhibitors should be considered as adjunct therapy in nerve agent poisoning to minimize nerve agent-induced seizure activity. Published by Elsevier B.V.

  19. Monoamines and neuropeptides interact to inhibit aversive behaviour in Caenorhabditis elegans.

    PubMed

    Mills, Holly; Wragg, Rachel; Hapiak, Vera; Castelletto, Michelle; Zahratka, Jeffrey; Harris, Gareth; Summers, Philip; Korchnak, Amanda; Law, Wenjing; Bamber, Bruce; Komuniecki, Richard

    2012-02-01

    Pain modulation is complex, but noradrenergic signalling promotes anti-nociception, with α(2)-adrenergic agonists used clinically. To better understand the noradrenergic/peptidergic modulation of nociception, we examined the octopaminergic inhibition of aversive behaviour initiated by the Caenorhabditis elegans nociceptive ASH sensory neurons. Octopamine (OA), the invertebrate counterpart of norepinephrine, modulates sensory-mediated reversal through three α-adrenergic-like OA receptors. OCTR-1 and SER-3 antagonistically modulate ASH signalling directly, with OCTR-1 signalling mediated by Gα(o). In contrast, SER-6 inhibits aversive responses by stimulating the release of an array of 'inhibitory' neuropeptides that activate receptors on sensory neurons mediating attraction or repulsion, suggesting that peptidergic signalling may integrate multiple sensory inputs to modulate locomotory transitions. These studies highlight the complexity of octopaminergic/peptidergic interactions, the role of OA in activating global peptidergic signalling cascades and the similarities of this modulatory network to the noradrenergic inhibition of nociception in mammals, where norepinephrine suppresses chronic pain through inhibitory α(2)-adrenoreceptors on afferent nociceptors and stimulatory α(1)-receptors on inhibitory peptidergic interneurons.

  20. Monoamines and neuropeptides interact to inhibit aversive behaviour in Caenorhabditis elegans

    PubMed Central

    Mills, Holly; Wragg, Rachel; Hapiak, Vera; Castelletto, Michelle; Zahratka, Jeffrey; Harris, Gareth; Summers, Philip; Korchnak, Amanda; Law, Wenjing; Bamber, Bruce; Komuniecki, Richard

    2012-01-01

    Pain modulation is complex, but noradrenergic signalling promotes anti-nociception, with α2-adrenergic agonists used clinically. To better understand the noradrenergic/peptidergic modulation of nociception, we examined the octopaminergic inhibition of aversive behaviour initiated by the Caenorhabditis elegans nociceptive ASH sensory neurons. Octopamine (OA), the invertebrate counterpart of norepinephrine, modulates sensory-mediated reversal through three α-adrenergic-like OA receptors. OCTR-1 and SER-3 antagonistically modulate ASH signalling directly, with OCTR-1 signalling mediated by Gαo. In contrast, SER-6 inhibits aversive responses by stimulating the release of an array of ‘inhibitory' neuropeptides that activate receptors on sensory neurons mediating attraction or repulsion, suggesting that peptidergic signalling may integrate multiple sensory inputs to modulate locomotory transitions. These studies highlight the complexity of octopaminergic/peptidergic interactions, the role of OA in activating global peptidergic signalling cascades and the similarities of this modulatory network to the noradrenergic inhibition of nociception in mammals, where norepinephrine suppresses chronic pain through inhibitory α2-adrenoreceptors on afferent nociceptors and stimulatory α1-receptors on inhibitory peptidergic interneurons. PMID:22124329

  1. Noradrenergic stimulation modulates activation of extinction-related brain regions and enhances contextual extinction learning without affecting renewal

    PubMed Central

    Lissek, Silke; Glaubitz, Benjamin; Güntürkün, Onur; Tegenthoff, Martin

    2015-01-01

    Renewal in extinction learning describes the recovery of an extinguished response if the extinction context differs from the context present during acquisition and recall. Attention may have a role in contextual modulation of behavior and contribute to the renewal effect, while noradrenaline (NA) is involved in attentional processing. In this functional magnetic resonance imaging (fMRI) study we investigated the role of the noradrenergic system for behavioral and brain activation correlates of contextual extinction and renewal, with a particular focus upon hippocampus and ventromedial prefrontal cortex (PFC), which have crucial roles in processing of renewal. Healthy human volunteers received a single dose of the NA reuptake inhibitor atomoxetine prior to extinction learning. During extinction of previously acquired cue-outcome associations, cues were presented in a novel context (ABA) or in the acquisition context (AAA). In recall, all cues were again presented in the acquisition context. Atomoxetine participants (ATO) showed significantly faster extinction compared to placebo (PLAC). However, atomoxetine did not affect renewal. Hippocampal activation was higher in ATO during extinction and recall, as was ventromedial PFC activation, except for ABA recall. Moreover, ATO showed stronger recruitment of insula, anterior cingulate, and dorsolateral/orbitofrontal PFC. Across groups, cingulate, hippocampus and vmPFC activity during ABA extinction correlated with recall performance, suggesting high relevance of these regions for processing the renewal effect. In summary, the noradrenergic system appears to be involved in the modification of established associations during extinction learning and thus has a role in behavioral flexibility. The assignment of an association to a context and the subsequent decision on an adequate response, however, presumably operate largely independently of noradrenergic mechanisms. PMID:25745389

  2. Noradrenergic Mechanisms of Arousal’s Bidirectional Effects on Episodic Memory

    PubMed Central

    Clewett, David; Sakaki, Michiko; Nielsen, Shawn; Petzinger, Giselle; Mather, Mara

    2016-01-01

    Arousal’s selective effects on cognition go beyond the simple enhancement of emotional stimuli, sometimes enhancing and other times impairing processing of proximal neutral information. Past work shows that arousal impairs encoding of subsequent neutral stimuli regardless of their top-down priority via the engagement of β-adrenoreceptors. In contrast, retrograde amnesia induced by emotional arousal can flip to enhancement when preceding neutral items are prioritized in top-down attention. Whether β-adrenoreceptors also contribute to this retrograde memory enhancement of goal-relevant neutral stimuli is unclear. In this pharmacological study, we administered 40mg of propranolol or 40mg of placebo to healthy young adults to examine whether emotional arousal’s bidirectional effects on declarative memory relies on β-adrenoreceptor activation. Following pill intake, participants completed an emotional oddball task in which they were asked to prioritize a neutral object appearing just before an emotional or neutral oddball image within a sequence of 7 neutral objects. Under placebo, emotional oddballs impaired memory for lower priority oddball+1 objects but had no effect on memory for high priority oddball−1 objects. Propranolol blocked this anterograde amnesic effect of arousal. Emotional oddballs also enhanced selective memory trade-offs significantly more in the placebo than drug condition, such that high priority oddball−1 objects were more likely to be remembered at the cost of their corresponding lower priority oddball+1 objects under arousal. Lastly, those who recalled more high priority oddball−1 objects preceding an emotional versus neutral oddball image showed greater increases in salivary alpha-amylase, a biomarker of noradrenergic system activation, across the task. Together these findings suggest that different noradrenergic mechanisms contribute to the anterograde and retrograde mnemonic effects of arousal on proximal neutral memoranda. PMID

  3. Ca2+-induced uncoupling of Aplysia bag cell neurons.

    PubMed

    Dargaei, Zahra; Standage, Dominic; Groten, Christopher J; Blohm, Gunnar; Magoski, Neil S

    2015-02-01

    Electrical transmission is a dynamically regulated form of communication and key to synchronizing neuronal activity. The bag cell neurons of Aplysia are a group of electrically coupled neuroendocrine cells that initiate ovulation by secreting egg-laying hormone during a prolonged period of synchronous firing called the afterdischarge. Accompanying the afterdischarge is an increase in intracellular Ca2+ and the activation of protein kinase C (PKC). We used whole cell recording from paired cultured bag cell neurons to demonstrate that electrical coupling is regulated by both Ca2+ and PKC. Elevating Ca2+ with a train of voltage steps, mimicking the onset of the afterdischarge, decreased junctional current for up to 30 min. Inhibition was most effective when Ca2+ entry occurred in both neurons. Depletion of Ca2+ from the mitochondria, but not the endoplasmic reticulum, also attenuated the electrical synapse. Buffering Ca2+ with high intracellular EGTA or inhibiting calmodulin kinase prevented uncoupling. Furthermore, activating PKC produced a small but clear decrease in junctional current, while triggering both Ca2+ influx and PKC inhibited the electrical synapse to a greater extent than Ca2+ alone. Finally, the amplitude and time course of the postsynaptic electrotonic response were attenuated after Ca2+ influx. A mathematical model of electrically connected neurons showed that excessive coupling reduced recruitment of the cells to fire, whereas less coupling led to spiking of essentially all neurons. Thus a decrease in electrical synapses could promote the afterdischarge by ensuring prompt recovery of electrotonic potentials or making the neurons more responsive to current spreading through the network. Copyright © 2015 the American Physiological Society.

  4. Selective Serotonergic (SSRI) Versus Noradrenergic (SNRI) Reuptake Inhibitors with and without Acetylsalicylic Acid in Major Depressive Disorder.

    PubMed

    Zdanowicz, Nicolas; Reynaert, Christine; Jacques, Denis; Lepiece, Brice; Dubois, Thomas

    2017-09-01

    Antidepressant medication efficacy remains a major research challenge. Here, we explored four questions: whether noradrenergic antidepressants are more effective than serotonergic antidepressants; whether the addition of 100 mg acetylsalicylic acid (ASA) changes antidepressant efficacy; whether the long-term efficacy differs depending on the antidepressant and the addition of ASA; and whether serum levels of brain-derived neurotrophic factor (BDNF) are clinically informative. In a two-year study, forty people with major depressive disorder were randomly assigned to groups that received an SSRI (escitalopram) or an SNRI (duloxetine), each group received concomitant ASA (100 mg) or a placebo. Sociodemographic data were recorded and patients under went regular assessments with the Hamilton depression scale (HDS) and clinical global impression (CGI) scale. Serum levels of BDNF were measured four times per year. There was no significant difference in efficacy between the two antidepressants or between antidepressant treatment with and without ASA. However, subgroup comparisons revealed that the duloxetine + ASA (DASA) subgroup showed a more rapid improvement in HDS score as early as 2 months (t=-3.114, p=0.01), in CGI score at 5 months (t=-2.119, p=0.05), and a better remission rate (χ 2 =6.296, p 0.012) than the escitalopram + placebo (EP) subgroup. Serum BDNF before treatment was also higher in the DASA subgroup than in the EP subgroup (t=3.713; p=0.002). This suggest two hypotheses: either a noradrenergic agent combined with ASA is more effective in treating depression than a serotonergic agent alone, or the level of serum BDNF before treatment is a precursor marker of the response to antidepressants. Further research is needed to test these hypotheses.

  5. Noradrenaline and acetylcholine responsiveness of glucose-monitoring and glucose-insensitive neurons in the mediodorsal prefrontal cortex.

    PubMed

    Nagy, Bernadett; Szabó, István; Csetényi, Bettina; Hormay, Edina; Papp, Szilárd; Keresztes, Dóra; Karádi, Zoltán

    2014-01-16

    The mediodorsal prefrontal cortex (mdPFC), as part of the forebrain glucose-monitoring (GM) system, plays important role in several regulatory processes to control the internal state of the organism and to initiate behavioral outputs accordingly. Little is known, however, about the neurochemical sensitivity of neurons located in this area. Substantial evidence indicates that the locus ceruleus - noradrenaline (NA) projection system and the nucleus basalis magnocellularis - cholinergic projection system regulate behavioral state and state dependent processing of sensory information, various cognitive functions already associated with the mdPFC. The main goal of the present study was to examine noradrenergic and cholinergic responsiveness of glucose-monitoring and glucose-insensitive (GIS) neurons in the mediodorsal prefrontal cortex. One fifth of the neurons tested changed in firing rate to microelectrophoretically applied NA. Responsiveness of the GM cells to this catecholamine proved to be significantly higher than that of the GIS units. Microiontophoretic application of acetylcholine (Ach) resulted in activity changes (predominantly facilitation) of more than 40% of the mdPFC neurons. Proportion of Ach sensitive units among the GM and the GIS neurons was found to be similar. The glucose-monitoring neurons of the mdPFC and their distinct NA and remarkable Ach sensitivity are suggested to be of particular significance in prefrontal control of adaptive behaviors. © 2013 Published by Elsevier B.V.

  6. Essential role of hippocampal noradrenaline in the regulation of spatial working memory and TDP-43 tissue pathology.

    PubMed

    Pintus, Roberta; Riggi, Margherita; Cannarozzo, Cecilia; Valeri, Andrea; de Leo, Gioacchino; Romano, Maurizio; Gulino, Rosario; Leanza, Giampiero

    2018-05-01

    Extensive loss of noradrenaline-containing neurons and fibers is a nearly invariant feature of Alzheimer's Disease (AD). However, the exact noradrenergic contribution to cognitive and histopathological changes in AD is still unclear. Here, this issue was addressed following selective lesioning and intrahippocampal implantation of embryonic noradrenergic progenitors in developing rats. Starting from about 3 months and up to 12 months post-surgery, animals underwent behavioral tests to evaluate sensory-motor, as well as spatial learning and memory, followed by post-mortem morphometric analyses. At 9 months, Control, Lesioned and Lesion + Transplant animals exhibited equally efficient sensory-motor and reference memory performance. Interestingly, working memory abilities were seen severely impaired in Lesion-only rats and fully recovered in Transplanted rats, and appeared partly lost again 2 months after ablation of the implanted neuroblasts. Morphological analyses confirmed the almost total lesion-induced noradrenergic neuronal and terminal fiber loss, the near-normal reinnervation of the hippocampus promoted by the transplants, and its complete removal by the second lesion. Notably, the noradrenergic-rich transplants normalized also the nuclear expression of the transactive response DNA-binding protein 43 (TDP-43) in various hippocampal subregions, whose cytoplasmic (i.e., pathological) occurrence appeared dramatically increased as a result of the lesions. Thus, integrity of ascending noradrenergic inputs to the hippocampus may be required for the regulation of specific aspects of learning and memory and to prevent TDP-43 tissue pathology. © 2018 Wiley Periodicals, Inc.

  7. Kv2.2: a novel molecular target to study the role of basal forebrain GABAergic neurons in the sleep-wake cycle.

    PubMed

    Hermanstyne, Tracey O; Subedi, Kalpana; Le, Wei Wei; Hoffman, Gloria E; Meredith, Andrea L; Mong, Jessica A; Misonou, Hiroaki

    2013-12-01

    The basal forebrain (BF) has been implicated as an important brain region that regulates the sleep-wake cycle of animals. Gamma-aminobutyric acidergic (GABAergic) neurons are the most predominant neuronal population within this region. However, due to the lack of specific molecular tools, the roles of the BF GABAergic neurons have not been fully elucidated. Previously, we have found high expression levels of the Kv2.2 voltage-gated potassium channel on approximately 60% of GABAergic neurons in the magnocellular preoptic area and horizontal limb of the diagonal band of Broca of the BF and therefore proposed it as a potential molecular target to study this neuronal population. In this study, we sought to determine the functional roles of the Kv2.2-expressing neurons in the regulation of the sleep-wake cycle. Sleep analysis between two genotypes and within each genotype before and after sleep deprivation. Animal sleep research laboratory. Adult mice. Wild-type and Kv2.2 knockout mice with C57/BL6 background. EEG/EMG recordings from the basal state and after sleep-deprivation which was induced by mild agitation for 6 h. Immunostaining of a marker of neuronal activity indicates that these Kv2.2-expressing neurons appear to be preferentially active during the wake state. Therefore, we tested whether Kv2.2-expressing neurons in the BF are involved in arousal using Kv2.2-deficient mice. BF GABAergic neurons exhibited augmented expression of c-Fos. These knockout mice exhibited longer consolidated wake bouts than wild-type littermates, and that phenotype was further exacerbated by sleep deprivation. Moreover, in-depth analyses of their cortical electroencephalogram revealed a significant decrease in the delta-frequency activity during the nonrapid eye movement sleep state. These results revealed the significance of Kv2.2-expressing neurons in the regulation of the sleep-wake cycle.

  8. Does Growth Impairment Underlie the Adverse Effects of Dexamethasone on Development of Noradrenergic Systems?

    PubMed

    Slotkin, Theodore A; Ko, Ashley; Seidler, Frederic J

    2018-06-20

    Glucocorticoids are given in preterm labor to prevent respiratory distress but these agents evoke neurobehavioral deficits in association with reduced brain region volumes. To determine whether the neurodevelopmental effects are distinct from growth impairment, we gave developing rats dexamethasone at doses below or within the therapeutic range (0.05, 0.2 or 0.8 mg/kg) at different stages: gestational days (GD) 17-19, postnatal days (PN) 1-3 or PN7-9. In adolescence and adulthood, we assessed the impact on noradrenergic systems in multiple brain regions, comparing the effects to those on somatic growth or on brain region growth. Somatic growth was reduced with exposure in all three stages, with greater sensitivity for the postnatal regimens; brain region growth was impaired to a lesser extent. Norepinephrine content and concentration were reduced depending on the treatment regimen, with a rank order of deficits of PN7-9 > PN1-3 > GD17-19. However, brain growth impairment did not parallel reduced norepinephrine content in magnitude, dose threshold, sex or regional selectivity, or temporal pattern, and even when corrected for reduced brain region weights (norepinephrine per g tissue), the dexamethasone-exposed animals showed subnormal values. Regression analysis showed that somatic growth impairment accounted for an insubstantial amount of the reduction in norepinephrine content, and brain growth impairment accounted for only 12%, whereas specific effects on norepinephrine accounted for most of the effect. The adverse effects of dexamethasone on noradrenergic system development are not simply related to impaired somatic or brain region growth, but rather include specific targeting of neurodifferentiation. Copyright © 2018. Published by Elsevier B.V.

  9. Cellular mechanisms underlying behavioral state-dependent bidirectional modulation of motor cortex output.

    PubMed

    Schiemann, Julia; Puggioni, Paolo; Dacre, Joshua; Pelko, Miha; Domanski, Aleksander; van Rossum, Mark C W; Duguid, Ian

    2015-05-26

    Neuronal activity in primary motor cortex (M1) correlates with behavioral state, but the cellular mechanisms underpinning behavioral state-dependent modulation of M1 output remain largely unresolved. Here, we performed in vivo patch-clamp recordings from layer 5B (L5B) pyramidal neurons in awake mice during quiet wakefulness and self-paced, voluntary movement. We show that L5B output neurons display bidirectional (i.e., enhanced or suppressed) firing rate changes during movement, mediated via two opposing subthreshold mechanisms: (1) a global decrease in membrane potential variability that reduced L5B firing rates (L5Bsuppressed neurons), and (2) a coincident noradrenaline-mediated increase in excitatory drive to a subpopulation of L5B neurons (L5Benhanced neurons) that elevated firing rates. Blocking noradrenergic receptors in forelimb M1 abolished the bidirectional modulation of M1 output during movement and selectively impaired contralateral forelimb motor coordination. Together, our results provide a mechanism for how noradrenergic neuromodulation and network-driven input changes bidirectionally modulate M1 output during motor behavior. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  10. Post-stress facilitation of serotonergic, but not noradrenergic, neurotransmission in the dorsal hippocampus prevents learned helplessness development in rats.

    PubMed

    Joca, Sâmia Regiane Lourenço; Zanelati, Tatiane; Guimarães, Francisco Silveira

    2006-05-04

    Recent pieces of evidence suggest that the dorsal hippocampus may mediate adaptation to severe and inescapable stress, possibly by the facilitation of serotonergic and/or noradrenergic neurotransmission. Chronic social stress and high corticosteroid levels would impair this coping mechanism, predisposing animals to learned helplessness. To test the hypothesis that increasing serotonin or noradrenaline levels in the dorsal hippocampus would attenuate the development of learned helplessness (LH), rats received inescapable foot shock (IS) and were tested in a shuttle box 24 h latter. Prestressed animals showed impairment of escape responses. This effect was prevented by bilateral intrahippocampal injections of zimelidine (100 nmol/0.5 microl), a serotonin reuptake blocker, immediately after IS. This effect was not observed when zimelidine was administered before or 2 h after IS. Bilateral intrahippocampal injections of desipramine (3 or 30 nmol/0.5 microl), a noradrenaline reuptake blocker, before IS or immediately after it did not prevent LH development. Desipramine (30 nmol) enhanced LH development when injected before IS. These data suggest that poststress facilitation of hippocampal serotonergic, but not noradrenergic, neurotransmission in the dorsal hippocampus facilitates adaptation to severe inescapable stress. Antidepressant effects of noradrenaline-selective drugs seem to depend on other structures than the dorsal hippocampus.

  11. Disinhibition by propranolol and chlordiazepoxide of nonrewarded lever-pressing in the rat is unaffected by dorsal noradrenergic bundle lesion.

    PubMed

    Salmon, P; Tsaltas, E; Gray, J A

    1989-03-01

    Ten male Sprague-Dawley rats received 6-hydroxydopamine-induced lesions of the dorsal noradrenergic bundle and 10 others underwent control operations. The lesion depleted levels of noradrenaline in the hippocampus to 2% of those in the controls. All rats were then trained for 16 sessions to lever-press in a Skinner box on a variable interval 18 sec schedule of food-reinforcement, then for 42 days on a successive discrimination between periods of variable interval (VI 18 sec) food-reinforcement and periods of extinction. This report describes the effects of chlordiazepoxide (CDP; 5 mg/kg) and propranolol (5 and 10 mg/kg) injected intraperitoneally in both groups on modified ABBA designs after this training. Both drugs increased the response rates in extinction periods. The effect of propranolol was similar at each dose and smaller than that of CDP. Although CDP and propranolol (5 mg/kg) increased variable interval response rates also, this could not account for the effect on extinction response rates. Responding did not differ between the lesioned and control animals and the effects of drugs were similar in each group. It is unlikely that CDP or propranolol release nonrewarded responding by disrupting transmission in the dorsal noradrenergic bundle.

  12. RhoA/Rho Kinase Mediates Neuronal Death Through Regulating cPLA2 Activation.

    PubMed

    Wu, Xiangbing; Walker, Chandler L; Lu, Qingbo; Wu, Wei; Eddelman, Daniel B; Parish, Jonathan M; Xu, Xiao-Ming

    2017-11-01

    Activation of RhoA/Rho kinase leads to growth cone collapse and neurite retraction. Although RhoA/Rho kinase inhibition has been shown to improve axon regeneration, remyelination and functional recovery, its role in neuronal cell death remains unclear. To determine whether RhoA/Rho kinase played a role in neuronal death after injury, we investigated the relationship between RhoA/Rho kinase and cytosolic phospholipase A 2 (cPLA 2 ), a lipase that mediates inflammation and cell death, using an in vitro neuronal death model and an in vivo contusive spinal cord injury model performed at the 10th thoracic (T10) vertebral level. We found that co-administration of TNF-α and glutamate induced spinal neuron death, and activation of RhoA, Rho kinase and cPLA 2 . Inhibition of RhoA, Rho kinase and cPLA 2 significantly reduced TNF-α/glutamate-induced cell death by 33, 52 and 43 %, respectively (p < 0.001). Inhibition of RhoA and Rho kinase also significantly downregulated cPLA 2 activation by 66 and 60 %, respectively (p < 0.01). Furthermore, inhibition of RhoA and Rho kinase reduced the release of arachidonic acid, a downstream substrate of cPLA 2 . The immunofluorescence staining showed that ROCK 1 or ROCK 2 , two isoforms of Rho kinase, was co-localized with cPLA 2 in neuronal cytoplasm. Interestingly, co-immunoprecipitation (Co-IP) assay showed that ROCK 1 or ROCK 2 bonded directly with cPLA 2 and phospho-cPLA 2 . When the Rho kinase inhibitor Y27632 was applied in mice with T10 contusion injury, it significantly decreased cPLA 2 activation and expression and reduced injury-induced apoptosis at and close to the lesion site. Taken together, our results reveal a novel mechanism of RhoA/Rho kinase-mediated neuronal death through regulating cPLA 2 activation.

  13. Hoxa2 and Hoxb2 control dorsoventral patterns of neuronal development in the rostral hindbrain.

    PubMed

    Davenne, M; Maconochie, M K; Neun, R; Pattyn, A; Chambon, P; Krumlauf, R; Rijli, F M

    1999-04-01

    Little is known about how the generation of specific neuronal types at stereotypic positions within the hindbrain is linked to Hox gene-mediated patterning. Here, we show that during neurogenesis, Hox paralog group 2 genes control both anteroposterior (A-P) and dorsoventral (D-V) patterning. Hoxa2 and Hoxb2 differentially regulate, in a rhombomere-specific manner, the expression of several genes in broad D-V-restricted domains or narrower longitudinal columns of neuronal progenitors, immature neurons, and differentiating neuronal subtypes. Moreover, Hoxa2 and Hoxb2 can functionally synergize in controlling the development of ventral neuronal subtypes in rhombomere 3 (r3). Thus, in addition to their roles in A-P patterning, Hoxa2 and Hoxb2 have distinct and restricted functions along the D-V axis during neurogenesis, providing insights into how neuronal fates are assigned at stereotypic positions within the hindbrain.

  14. Kv2.2: A Novel Molecular Target to Study the Role of Basal Forebrain GABAergic Neurons in the Sleep-Wake Cycle

    PubMed Central

    Hermanstyne, Tracey O.; Subedi, Kalpana; Le, Wei Wei; Hoffman, Gloria E.; Meredith, Andrea L.; Mong, Jessica A.; Misonou, Hiroaki

    2013-01-01

    Study Objectives: The basal forebrain (BF) has been implicated as an important brain region that regulates the sleep-wake cycle of animals. Gamma-aminobutyric acidergic (GABAergic) neurons are the most predominant neuronal population within this region. However, due to the lack of specific molecular tools, the roles of the BF GABAergic neurons have not been fully elucidated. Previously, we have found high expression levels of the Kv2.2 voltage-gated potassium channel on approximately 60% of GABAergic neurons in the magnocellular preoptic area and horizontal limb of the diagonal band of Broca of the BF and therefore proposed it as a potential molecular target to study this neuronal population. In this study, we sought to determine the functional roles of the Kv2.2-expressing neurons in the regulation of the sleep-wake cycle. Design: Sleep analysis between two genotypes and within each genotype before and after sleep deprivation. Setting: Animal sleep research laboratory. Participants: Adult mice. Wild-type and Kv2.2 knockout mice with C57/BL6 background. Interventions: EEG/EMG recordings from the basal state and after sleep-deprivation which was induced by mild aggitation for 6 h. Results: Immunostaining of a marker of neuronal activity indicates that these Kv2.2-expressing neurons appear to be preferentially active during the wake state. Therefore, we tested whether Kv2.2-expressing neurons in the BF are involved in arousal using Kv2.2-deficient mice. BF GABAergic neurons exhibited augmented expression of c-Fos. These knockout mice exhibited longer consolidated wake bouts than wild-type littermates, and that phenotype was further exacerbated by sleep deprivation. Moreover, in-depth analyses of their cortical electroencephalogram revealed a significant decrease in the delta-frequency activity during the nonrapid eye movement sleep state. Conclusions: These results revealed the significance of Kv2.2-expressing neurons in the regulation of the sleep-wake cycle

  15. CHOLINERGIC AND NORADRENERGIC MODULATION OF LONG-TERM EXPLICIT MEMORY ARE ALTERED BY CHRONIC LOW-LEVEL LEAD EXPOSURE. (U915393)

    EPA Science Inventory

    Recent evidence suggests that septohippocampal cholinergic activity is suppressed in rats exposed to low levels of lead (Pb). As a result, noradrenergic activity may be elevated due to compensatory sympathetic sprouting. Therefore, the goals of this study were to (a) determine...

  16. Localization of multiple neurotransmitters in surgically derived specimens of human atrial ganglia.

    PubMed

    Hoover, D B; Isaacs, E R; Jacques, F; Hoard, J L; Pagé, P; Armour, J A

    2009-12-15

    Dysfunction of the intrinsic cardiac nervous system is implicated in the genesis of atrial and ventricular arrhythmias. While this system has been studied extensively in animal models, far less is known about the intrinsic cardiac nervous system of humans. This study was initiated to anatomically identify neurotransmitters associated with the right atrial ganglionated plexus (RAGP) of the human heart. Biopsies of epicardial fat containing a portion of the RAGP were collected from eight patients during cardiothoracic surgery and processed for immunofluorescent detection of specific neuronal markers. Colocalization of markers was evaluated by confocal microscopy. Most intrinsic cardiac neuronal somata displayed immunoreactivity for the cholinergic marker choline acetyltransferase and the nitrergic marker neuronal nitric oxide synthase. A subpopulation of intrinsic cardiac neurons also stained for noradrenergic markers. While most intrinsic cardiac neurons received cholinergic innervation evident as punctate immunostaining for the high affinity choline transporter, some lacked cholinergic inputs. Moreover, peptidergic, nitrergic, and noradrenergic nerves provided substantial innervation of intrinsic cardiac ganglia. These findings demonstrate that the human RAGP has a complex neurochemical anatomy, which includes the presence of a dual cholinergic/nitrergic phenotype for most of its neurons, the presence of noradrenergic markers in a subpopulation of neurons, and innervation by a host of neurochemically distinct nerves. The putative role of multiple neurotransmitters in controlling intrinsic cardiac neurons and mediating efferent signaling to the heart indicates the possibility of novel therapeutic targets for arrhythmia prevention.

  17. Estradiol regulates responsiveness of the dorsal premammillary nucleus of the hypothalamus and affects fear- and anxiety-like behaviors in female rats.

    PubMed

    Litvin, Yoav; Cataldo, Giuseppe; Pfaff, Donald W; Kow, Lee-Ming

    2014-07-01

    Research suggests a causal link between estrogens and mood. Here, we began by examining the effects of estradiol (E2 ) on rat innate and conditioned defensive behaviors in response to cat odor. Second, we utilized whole-cell patch clamp electrophysiological techniques to assess noradrenergic effects on neurons within the dorsal premammillary nucleus of the hypothalamus (PMd), a nucleus implicated in fear reactivity, and their regulation by E2 . Our results show that E2 increased general arousal and modified innate defensive reactivity to cat odor. When ovariectomized females treated with E2 as opposed to oil were exposed to cat odor, they showed elevations in risk assessment and reductions in freezing, indicating a shift from passive to active coping. In addition, animals previously exposed to cat odor showed clear cue + context conditioning 24 h later. However, although E2 persisted in its effects on general arousal in the conditioning task, its effects on fear disappeared. In the patch clamp experiments noradrenergic compounds that typically induce fear clearly excited PMd neurons, producing depolarizations and action potentials. E2 treatment shifted some excitatory effects of noradrenergic agonists to inhibitory, possibly by differentially affecting α- and β-adrenoreceptors. In summary, our results implicate E2 in general arousal and fear reactivity, and suggest these may be governed by changes in noradrenergic responsivity in the PMd. These effects of E2 may have ethological relevance, serving to promote mate seeking even in contexts of ambiguous threat and shed light on the involvement of estrogen in mood and its associated disorders. © 2014 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  18. Temperature influences neuronal activity and CO2/pH sensitivity of locus coeruleus neurons in the bullfrog, Lithobates catesbeianus.

    PubMed

    Santin, Joseph M; Watters, Kayla C; Putnam, Robert W; Hartzler, Lynn K

    2013-12-15

    The locus coeruleus (LC) is a chemoreceptive brain stem region in anuran amphibians and contains neurons sensitive to physiological changes in CO2/pH. The ventilatory and central sensitivity to CO2/pH is proportional to the temperature in amphibians, i.e., sensitivity increases with increasing temperature. We hypothesized that LC neurons from bullfrogs, Lithobates catesbeianus, would increase CO2/pH sensitivity with increasing temperature and decrease CO2/pH sensitivity with decreasing temperature. Further, we hypothesized that cooling would decrease, while warming would increase, normocapnic firing rates of LC neurons. To test these hypotheses, we used whole cell patch-clamp electrophysiology to measure firing rate, membrane potential (V(m)), and input resistance (R(in)) in LC neurons in brain stem slices from adult bullfrogs over a physiological range of temperatures during normocapnia and hypercapnia. We found that cooling reduced chemosensitive responses of LC neurons as temperature decreased until elimination of CO2/pH sensitivity at 10°C. Chemosensitive responses increased at elevated temperatures. Surprisingly, chemosensitive LC neurons increased normocapnic firing rate and underwent membrane depolarization when cooled and decreased normocapnic firing rate and underwent membrane hyperpolarization when warmed. These responses to temperature were not observed in nonchemosensitive LC neurons or neurons in a brain stem slice 500 μm rostral to the LC. Our results indicate that modulation of cellular chemosensitivity within the LC during temperature changes may influence temperature-dependent respiratory drive during acid-base disturbances in amphibians. Additionally, cold-activated/warm-inhibited LC neurons introduce paradoxical temperature sensitivity in respiratory control neurons of amphibians.

  19. Energy imbalance alters Ca2+ handling and excitability of POMC neurons

    PubMed Central

    Paeger, Lars; Pippow, Andreas; Hess, Simon; Paehler, Moritz; Klein, Andreas C; Husch, Andreas; Pouzat, Christophe; Brüning, Jens C; Kloppenburg, Peter

    2017-01-01

    Satiety-signaling, pro-opiomelanocortin (POMC)-expressing neurons in the arcuate nucleus of the hypothalamus play a pivotal role in the regulation of energy homeostasis. Recent studies reported altered mitochondrial dynamics and decreased mitochondria- endoplasmic reticulum contacts in POMC neurons during diet-induced obesity. Since mitochondria play a crucial role in Ca2+ signaling, we investigated whether obesity alters Ca2+ handling of these neurons in mice. In diet-induced obesity, cellular Ca2+ handling properties including mitochondrial Ca2+ uptake capacity are impaired, and an increased resting level of free intracellular Ca2+ is accompanied by a marked decrease in neuronal excitability. Experimentally increasing or decreasing intracellular Ca2+ concentrations reproduced electrophysiological properties observed in diet-induced obesity. Taken together, we provide the first direct evidence for a diet-dependent deterioration of Ca2+ homeostasis in POMC neurons during obesity development resulting in impaired function of these critical energy homeostasis-regulating neurons. DOI: http://dx.doi.org/10.7554/eLife.25641.001 PMID:28762947

  20. Functional Neuroanatomy of the Noradrenergic Locus Coeruleus: Its Roles in the Regulation of Arousal and Autonomic Function Part II: Physiological and Pharmacological Manipulations and Pathological Alterations of Locus Coeruleus Activity in Humans

    PubMed Central

    Samuels, E. R; Szabadi, E

    2008-01-01

    The locus coeruleus (LC), the major noradrenergic nucleus of the brain, gives rise to fibres innervating most structures of the neuraxis. Recent advances in neuroscience have helped to unravel the neuronal circuitry controlling a number of physiological functions in which the LC plays a central role. Two such functions are the regulation of arousal and autonomic activity, which are inseparably linked largely via the involvement of the LC. Alterations in LC activity due to physiological or pharmacological manipulations or pathological processes can lead to distinct patterns of change in arousal and autonomic function. Physiological manipulations considered here include the presentation of noxious or anxiety-provoking stimuli and extremes in ambient temperature. The modification of LC-controlled functions by drug administration is discussed in detail, including drugs which directly modify the activity of LC neurones (e.g., via autoreceptors, storage, reuptake) or have an indirect effect through modulating excitatory or inhibitory inputs. The early vulnerability of the LC to the ageing process and to neurodegenerative disease (Parkinson’s and Alzheimer’s diseases) is of considerable clinical significance. In general, physiological manipulations and the administration of stimulant drugs, α2-adrenoceptor antagonists and noradrenaline uptake inhibitors increase LC activity and thus cause heightened arousal and activation of the sympathetic nervous system. In contrast, the administration of sedative drugs, including α2-adrenoceptor agonists, and pathological changes in LC function in neurodegenerative disorders and ageing reduce LC activity and result in sedation and activation of the parasympathetic nervous system. PMID:19506724

  1. Neto2 Assembles with Kainate Receptors in DRG Neurons during Development and Modulates Neurite Outgrowth in Adult Sensory Neurons

    PubMed Central

    Vernon, Claire G.

    2017-01-01

    Peripheral sensory neurons in the dorsal root ganglia (DRG) are the initial transducers of sensory stimuli, including painful stimuli, from the periphery to central sensory and pain-processing centers. Small- to medium-diameter non-peptidergic neurons in the neonatal DRG express functional kainate receptors (KARs), one of three subfamilies of ionotropic glutamate receptors, as well as the putative KAR auxiliary subunit Neuropilin- and tolloid-like 2 (Neto2). Neto2 alters recombinant KAR function markedly but has yet to be confirmed as an auxiliary subunit that assembles with and alters the function of endogenous KARs. KARs in neonatal DRG require the GluK1 subunit as a necessary constituent, but it is unclear to what extent other KAR subunits contribute to the function and proposed roles of KARs in sensory ganglia, which include promotion of neurite outgrowth and modulation of glutamate release at the DRG–dorsal horn synapse. In addition, KARs containing the GluK1 subunit are implicated in modes of persistent but not acute pain signaling. We show here that the Neto2 protein is highly expressed in neonatal DRG and modifies KAR gating in DRG neurons in a developmentally regulated fashion in mice. Although normally at very low levels in adult DRG neurons, Neto2 protein expression can be upregulated via MEK/ERK signaling and after sciatic nerve crush and Neto2−/− neurons from adult mice have stunted neurite outgrowth. These data confirm that Neto2 is a bona fide KAR auxiliary subunit that is an important constituent of KARs early in sensory neuron development and suggest that Neto2 assembly is critical to KAR modulation of DRG neuron process outgrowth. SIGNIFICANCE STATEMENT Pain-transducing peripheral sensory neurons of the dorsal root ganglia (DRG) express kainate receptors (KARs), a subfamily of glutamate receptors that modulate neurite outgrowth and regulate glutamate release at the DRG–dorsal horn synapse. The putative KAR auxiliary subunit Neuropilin- and

  2. Sequential EMT-MET induces neuronal conversion through Sox2

    PubMed Central

    He, Songwei; Chen, Jinlong; Zhang, Yixin; Zhang, Mengdan; Yang, Xiao; Li, Yuan; Sun, Hao; Lin, Lilong; Fan, Ke; Liang, Lining; Feng, Chengqian; Wang, Fuhui; Zhang, Xiao; Guo, Yiping; Pei, Duanqing; Zheng, Hui

    2017-01-01

    Direct neuronal conversion can be achieved with combinations of small-molecule compounds and growth factors. Here, by studying the first or induction phase of the neuronal conversion induced by defined 5C medium, we show that the Sox2-mediated switch from early epithelial–mesenchymal transition (EMT) to late mesenchymal–epithelial transition (MET) within a high proliferation context is essential and sufficient for the conversion from mouse embryonic fibroblasts (MEFs) to TuJ+ cells. At the early stage, insulin and basic fibroblast growth factor (bFGF)-induced cell proliferation, early EMT, the up-regulation of Stat3 and Sox2, and the subsequent activation of neuron projection. Up-regulated Sox2 then induced MET and directed cells towards a neuronal fate at the late stage. Inhibiting either stage of this sequential EMT-MET impaired the conversion. In addition, Sox2 could replace sequential EMT-MET to induce a similar conversion within a high proliferation context, and its functions were confirmed with other neuronal conversion protocols and MEFs reprogramming. Therefore, the critical roles of the sequential EMT-MET were implicated in direct cell fate conversion in addition to reprogramming, embryonic development and cancer progression. PMID:28580167

  3. Neuronal networks and mediators of cortical neurovascular coupling responses in normal and altered brain states.

    PubMed

    Lecrux, C; Hamel, E

    2016-10-05

    Brain imaging techniques that use vascular signals to map changes in neuronal activity, such as blood oxygenation level-dependent functional magnetic resonance imaging, rely on the spatial and temporal coupling between changes in neurophysiology and haemodynamics, known as 'neurovascular coupling (NVC)'. Accordingly, NVC responses, mapped by changes in brain haemodynamics, have been validated for different stimuli under physiological conditions. In the cerebral cortex, the networks of excitatory pyramidal cells and inhibitory interneurons generating the changes in neural activity and the key mediators that signal to the vascular unit have been identified for some incoming afferent pathways. The neural circuits recruited by whisker glutamatergic-, basal forebrain cholinergic- or locus coeruleus noradrenergic pathway stimulation were found to be highly specific and discriminative, particularly when comparing the two modulatory systems to the sensory response. However, it is largely unknown whether or not NVC is still reliable when brain states are altered or in disease conditions. This lack of knowledge is surprising since brain imaging is broadly used in humans and, ultimately, in conditions that deviate from baseline brain function. Using the whisker-to-barrel pathway as a model of NVC, we can interrogate the reliability of NVC under enhanced cholinergic or noradrenergic modulation of cortical circuits that alters brain states.This article is part of the themed issue 'Interpreting BOLD: a dialogue between cognitive and cellular neuroscience'. © 2016 The Author(s).

  4. A kainate receptor subunit promotes the recycling of the neuron-specific K+-Cl- co-transporter KCC2 in hippocampal neurons.

    PubMed

    Pressey, Jessica C; Mahadevan, Vivek; Khademullah, C Sahara; Dargaei, Zahra; Chevrier, Jonah; Ye, Wenqing; Huang, Michelle; Chauhan, Alamjeet K; Meas, Steven J; Uvarov, Pavel; Airaksinen, Matti S; Woodin, Melanie A

    2017-04-14

    Synaptic inhibition depends on a transmembrane gradient of chloride, which is set by the neuron-specific K + -Cl - co-transporter KCC2. Reduced KCC2 levels in the neuronal membrane contribute to the generation of epilepsy, neuropathic pain, and autism spectrum disorders; thus, it is important to characterize the mechanisms regulating KCC2 expression. In the present study, we determined the role of KCC2-protein interactions in regulating total and surface membrane KCC2 expression. Using quantitative immunofluorescence in cultured mouse hippocampal neurons, we discovered that the kainate receptor subunit GluK2 and the auxiliary subunit Neto2 significantly increase the total KCC2 abundance in neurons but that GluK2 exclusively increases the abundance of KCC2 in the surface membrane. Using a live cell imaging assay, we further determined that KCC2 recycling primarily occurs within 1-2 h and that GluK2 produces an ∼40% increase in the amount of KCC2 recycled to the membrane during this time period. This GluK2-mediated increase in surface recycling translated to a significant increase in KCC2 expression in the surface membrane. Moreover, we found that KCC2 recycling is enhanced by protein kinase C-mediated phosphorylation of the GluK2 C-terminal residues Ser-846 and Ser-868. Lastly, using gramicidin-perforated patch clamp recordings, we found that the GluK2-mediated increase in KCC2 recycling to the surface membrane translates to a hyperpolarization of the reversal potential for GABA (E GABA ). In conclusion, our results have revealed a mechanism by which kainate receptors regulate KCC2 expression in the hippocampus. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  5. APLP2 regulates neuronal stem cell differentiation during cortical development.

    PubMed

    Shariati, S Ali M; Lau, Pierre; Hassan, Bassem A; Müller, Ulrike; Dotti, Carlos G; De Strooper, Bart; Gärtner, Annette

    2013-03-01

    Expression of amyloid precursor protein (APP) and its two paralogues, APLP1 and APLP2 during brain development coincides with key cellular events such as neuronal differentiation and migration. However, genetic knockout and shRNA studies have led to contradictory conclusions about their role during embryonic brain development. To address this issue, we analysed in depth the role of APLP2 during neurogenesis by silencing APLP2 in vivo in an APP/APLP1 double knockout mouse background. We find that under these conditions cortical progenitors remain in their undifferentiated state much longer, displaying a higher number of mitotic cells. In addition, we show that neuron-specific APLP2 downregulation does not impact the speed or position of migrating excitatory cortical neurons. In summary, our data reveal that APLP2 is specifically required for proper cell cycle exit of neuronal progenitors, and thus has a distinct role in priming cortical progenitors for neuronal differentiation.

  6. FOXP2 drives neuronal differentiation by interacting with retinoic acid signaling pathways.

    PubMed

    Devanna, Paolo; Middelbeek, Jeroen; Vernes, Sonja C

    2014-01-01

    FOXP2 was the first gene shown to cause a Mendelian form of speech and language disorder. Although developmentally expressed in many organs, loss of a single copy of FOXP2 leads to a phenotype that is largely restricted to orofacial impairment during articulation and linguistic processing deficits. Why perturbed FOXP2 function affects specific aspects of the developing brain remains elusive. We investigated the role of FOXP2 in neuronal differentiation and found that FOXP2 drives molecular changes consistent with neuronal differentiation in a human model system. We identified a network of FOXP2 regulated genes related to retinoic acid signaling and neuronal differentiation. FOXP2 also produced phenotypic changes associated with neuronal differentiation including increased neurite outgrowth and reduced migration. Crucially, cells expressing FOXP2 displayed increased sensitivity to retinoic acid exposure. This suggests a mechanism by which FOXP2 may be able to increase the cellular differentiation response to environmental retinoic acid cues for specific subsets of neurons in the brain. These data demonstrate that FOXP2 promotes neuronal differentiation by interacting with the retinoic acid signaling pathway and regulates key processes required for normal circuit formation such as neuronal migration and neurite outgrowth. In this way, FOXP2, which is found only in specific subpopulations of neurons in the brain, may drive precise neuronal differentiation patterns and/or control localization and connectivity of these FOXP2 positive cells.

  7. FOXP2 drives neuronal differentiation by interacting with retinoic acid signaling pathways

    PubMed Central

    Devanna, Paolo; Middelbeek, Jeroen; Vernes, Sonja C.

    2014-01-01

    FOXP2 was the first gene shown to cause a Mendelian form of speech and language disorder. Although developmentally expressed in many organs, loss of a single copy of FOXP2 leads to a phenotype that is largely restricted to orofacial impairment during articulation and linguistic processing deficits. Why perturbed FOXP2 function affects specific aspects of the developing brain remains elusive. We investigated the role of FOXP2 in neuronal differentiation and found that FOXP2 drives molecular changes consistent with neuronal differentiation in a human model system. We identified a network of FOXP2 regulated genes related to retinoic acid signaling and neuronal differentiation. FOXP2 also produced phenotypic changes associated with neuronal differentiation including increased neurite outgrowth and reduced migration. Crucially, cells expressing FOXP2 displayed increased sensitivity to retinoic acid exposure. This suggests a mechanism by which FOXP2 may be able to increase the cellular differentiation response to environmental retinoic acid cues for specific subsets of neurons in the brain. These data demonstrate that FOXP2 promotes neuronal differentiation by interacting with the retinoic acid signaling pathway and regulates key processes required for normal circuit formation such as neuronal migration and neurite outgrowth. In this way, FOXP2, which is found only in specific subpopulations of neurons in the brain, may drive precise neuronal differentiation patterns and/or control localization and connectivity of these FOXP2 positive cells. PMID:25309332

  8. Systemic administration of guanfacine improves food-motivated impulsive choice behavior primarily via direct stimulation of postsynaptic α2A-adrenergic receptors in rats.

    PubMed

    Nishitomi, Kouhei; Yano, Koji; Kobayashi, Mika; Jino, Kohei; Kano, Takuya; Horiguchi, Naotaka; Shinohara, Shunji; Hasegawa, Minoru

    2018-06-01

    Impulsive choice behavior, which can be assessed using the delay discounting task, is a characteristic of various psychiatric disorders, including attention-deficit/hyperactivity disorder (ADHD). Guanfacine is a selective α 2A -adrenergic receptor agonist that is clinically effective in treating ADHD. However, there is no clear evidence that systemic guanfacine administration reduces impulsive choice behavior in the delay discounting task in rats. In the present study, we examined the effect of systemic guanfacine administration on food-motivated impulsive choice behavior in rats and the neuronal mechanism underlying this effect. Repeated administration of either guanfacine, methylphenidate, or atomoxetine significantly enhanced impulse control, increasing the number of times the rats chose a large but delayed reward in a dose-dependent manner. The effect of guanfacine was significantly blocked by pretreatment with an α 2A -adrenergic receptor antagonist. Furthermore, the effect of guanfacine remained unaffected in rats pretreated with a selective noradrenergic neurotoxin, consistent with a post-synaptic action. In contrast, the effect of atomoxetine on impulsive choice behavior was attenuated by pretreatment with the noradrenergic neurotoxin. These results provide the first evidence that systemically administered guanfacine reduces impulsive choice behavior in rats and that direct stimulation of postsynaptic, rather than presynaptic, α 2A -adrenergic receptors is involved in this effect. Copyright © 2018 Elsevier B.V. All rights reserved.

  9. Positive regulation of raphe serotonin neurons by serotonin 2B receptors.

    PubMed

    Belmer, Arnauld; Quentin, Emily; Diaz, Silvina L; Guiard, Bruno P; Fernandez, Sebastian P; Doly, Stéphane; Banas, Sophie M; Pitychoutis, Pothitos M; Moutkine, Imane; Muzerelle, Aude; Tchenio, Anna; Roumier, Anne; Mameli, Manuel; Maroteaux, Luc

    2018-06-01

    Serotonin is a neurotransmitter involved in many psychiatric diseases. In humans, a lack of 5-HT 2B receptors is associated with serotonin-dependent phenotypes, including impulsivity and suicidality. A lack of 5-HT 2B receptors in mice eliminates the effects of molecules that directly target serotonergic neurons including amphetamine derivative serotonin releasers, and selective serotonin reuptake inhibitor antidepressants. In this work, we tested the hypothesis that 5-HT 2B receptors directly and positively regulate raphe serotonin neuron activity. By ex vivo electrophysiological recordings, we report that stimulation by the 5-HT 2B receptor agonist, BW723C86, increased the firing frequency of serotonin Pet1-positive neurons. Viral overexpression of 5-HT 2B receptors in these neurons increased their excitability. Furthermore, in vivo 5-HT 2B -receptor stimulation by BW723C86 counteracted 5-HT 1A autoreceptor-dependent reduction in firing rate and hypothermic response in wild-type mice. By a conditional genetic ablation that eliminates 5-HT 2B receptor expression specifically and exclusively from Pet1-positive serotonin neurons (Htr2b 5-HTKO mice), we demonstrated that behavioral and sensitizing effects of MDMA (3,4-methylenedioxy-methamphetamine), as well as acute behavioral and chronic neurogenic effects of the antidepressant fluoxetine, require 5-HT 2B receptor expression in serotonergic neurons. In Htr2b 5-HTKO mice, dorsal raphe serotonin neurons displayed a lower firing frequency compared to control Htr2b lox/lox mice as assessed by in vivo extracellular recordings and a stronger hypothermic effect of 5-HT 1A -autoreceptor stimulation was observed. The increase in head-twitch response to DOI (2,5-dimethoxy-4-iodoamphetamine) further confirmed the lower serotonergic tone resulting from the absence of 5-HT 2B receptors in serotonin neurons. Together, these observations indicate that the 5-HT 2B receptor acts as a direct positive modulator of serotonin Pet1

  10. Intermittent Short Sleep Results in Lasting Sleep Wake Disturbances and Degeneration of Locus Coeruleus and Orexinergic Neurons

    PubMed Central

    Zhu, Yan; Fenik, Polina; Zhan, Guanxia; Somach, Rebecca; Xin, Ryan; Veasey, Sigrid

    2016-01-01

    Study Objectives: Intermittent short sleep (ISS) is pervasive among students and workers in modern societies, yet the lasting consequences of repeated short sleep on behavior and brain health are largely unexplored. Wake-activated neurons may be at increased risk of metabolic injury across sustained wakefulness. Methods: To examine the effects of ISS on wake-activated neurons and wake behavior, wild-type mice were randomized to ISS (a repeated pattern of short sleep on 3 consecutive days followed by 4 days of recovery sleep for 4 weeks) or rested control conditions. Subsets of both groups were allowed a recovery period consisting of 4-week unperturbed activity in home cages with littermates. Mice were examined for immediate and delayed (following recovery) effects of ISS on wake neuron cell metabolics, cell counts, and sleep/wake patterns. Results: ISS resulted in sustained disruption of sleep/wake activity, with increased wakefulness during the lights-on period and reduced wake bout duration and wake time during the lights-off period. Noradrenergic locus coeruleus (LC) and orexinergic neurons showed persistent alterations in morphology, and reductions in both neuronal stereological cell counts and fronto-cortical projections. Surviving wake-activated neurons evidenced persistent reductions in sirtuins 1 and 3 and increased lipofuscin. In contrast, ISS resulted in no lasting injury to the sleep-activated melanin concentrating hormone neurons. Conclusions: Collectively these findings demonstrate for the first time that ISS imparts significant lasting disturbances in sleep/wake activity, degeneration of wake-activated LC and orexinergic neurons, and lasting metabolic changes in remaining neurons most consistent with premature senescence. Citation: Zhu Y, Fenik P, Zhan G, Somach R, Xin R, Veasey S. Intermittent short sleep results in lasting sleep wake disturbances and degeneration of locus coeruleus and orexinergic neurons. SLEEP 2016;39(8):1601–1611. PMID:27306266

  11. Kinases of eIF2a Switch Translation of mRNA Subset during Neuronal Plasticity

    PubMed Central

    Chesnokova, Ekaterina; Bal, Natalia

    2017-01-01

    Compared to other types of cells, neurons express the largest number of diverse mRNAs, including neuron-specific ones. This mRNA diversity is required for neuronal function, memory storage, maintenance and retrieval. Regulation of translation in neurons is very complicated and involves various proteins. Some proteins, implementing translational control in other cell types, are used by neurons for synaptic plasticity. In this review, we discuss the neuron-specific activity of four kinases: protein kinase R (PKR), PKR-like endoplasmic reticulum kinase (PERK), general control nonderepressible 2 kinase (GCN2), and heme-reguated eIF2α kinase (HRI), the substrate for which is α-subunit of eukaryotic initiation factor 2 (eIF2α). Phosphorylation of eIF2α is necessary for the cell during stress conditions, such as lack of amino acids, energy stress or viral infection. We propose that, during memory formation, neurons use some mechanisms similar to those involved in the cellular stress. The four eIF2α kinases regulate translation of certain mRNAs containing upstream open reading frames (uORFs). These mRNAs encode proteins involved in the processes of long-term potentiation (LTP) or long-term depression (LTD). The review examines some neuronal proteins for which translation regulation by eIF2 was suggested and checked experimentally. Of such proteins, we pay close attention to protein kinase Mζ, which is involved in memory storage and regulated at the translational level. PMID:29065505

  12. Development of Ca2+ hotspots between Lymnaea neurons during synaptogenesis

    PubMed Central

    Feng, Zhong-Ping; Grigoriev, Nikita; Munno, David; Lukowiak, Ken; MacVicar, Brian A; Goldberg, Jeffrey I; Syed, Naweed I

    2002-01-01

    Calcium (Ca2+) channel clustering at specific presynaptic sites is a hallmark of mature synapses. However, the spatial distribution patterns of Ca2+ channels at newly formed synapses have not yet been demonstrated. Similarly, it is unclear whether Ca2+ ‘hotspots’ often observed at the presynaptic sites are indeed target cell contact specific and represent a specialized mechanism by which Ca2+ channels are targeted to select synaptic sites. Utilizing both soma–soma paired (synapsed) and single neurons from the mollusk Lymnaea, we have tested the hypothesis that differential gradients of voltage-dependent Ca2+ signals develop in presynaptic neuron at its contact point with the postsynaptic neuron; and that these Ca2+ hotspots are target cell contact specific. Fura-2 imaging, or two-photon laser scanning microscopy of Calcium Green, was coupled with electrophysiological techniques to demonstrate that voltage-induced Ca2+ gradients (hotspots) develop in the presynaptic cell at its contact point with the postsynaptic neuron, but not in unpaired single cells. The incidence of Ca2+ hotspots coincided with the appearance of synaptic transmission between the paired cells, and these gradients were target cell contact specific. In contrast, the voltage-induced Ca2+ signal in unpaired neurons was uniformly distributed throughout the somata; a similar pattern of Ca2+ gradient was observed in the presynaptic neuron when it was soma–soma paired with a non-synaptic partner cell. Moreover, voltage clamp recording techniques, in conjunction with a fast, optical differential perfusion system, were used to demonstrate that the total whole-cell Ca2+ (or Ba2+) current density in single and paired cells was not significantly different. However, the amplitude of Ba2+ current was significantly higher in the presynaptic cell at its contact side with the postsynaptic neurons, compared with non-contacted regions. In summary, this study demonstrates that voltage-induced Ca2+ hotspots

  13. Deletion of Otx2 in GnRH neurons results in a mouse model of hypogonadotropic hypogonadism.

    PubMed

    Diaczok, Daniel; DiVall, Sara; Matsuo, Isao; Wondisford, Fredric E; Wolfe, Andrew M; Radovick, Sally

    2011-05-01

    GnRH is the central regulator of reproductive function responding to central nervous system cues to control gonadotropin synthesis and secretion. GnRH neurons originate in the olfactory placode and migrate to the forebrain, in which they are found in a scattered distribution. Congenital idiopathic hypogonadotropic hypogonadism (CIHH) has been associated with mutations or deletions in a number of genes that participate in the development of GnRH neurons and expression of GnRH. Despite the critical role of GnRH in mammalian reproduction, a comprehensive understanding of the developmental factors that are responsible for regulating the establishment of mature GnRH neurons and the expression of GnRH is lacking. orthodenticle homeobox 2 (OTX2), a homeodomain protein required for the formation of the forebrain, has been shown to be expressed in GnRH neurons, up-regulated during GnRH neuronal development, and responsible for increased GnRH promoter activity in GnRH neuronal cell lines. Interestingly, mutations in Otx2 have been associated with human hypogonadotropic hypogonadism, but the mechanism by which Otx2 mutations cause CIHH is unknown. Here we show that deletion of Otx2 in GnRH neurons results in a significant decrease in GnRH neurons in the hypothalamus, a delay in pubertal onset, abnormal estrous cyclicity, and infertility. Taken together, these data provide in vivo evidence that Otx2 is critical for GnRH expression and reproductive competence.

  14. The NG2 Protein Is Not Required for Glutamatergic Neuron-NG2 Cell Synaptic Signaling.

    PubMed

    Passlick, Stefan; Trotter, Jacqueline; Seifert, Gerald; Steinhäuser, Christian; Jabs, Ronald

    2016-01-01

    NG2 glial cells (as from now NG2 cells) are unique in receiving synaptic input from neurons. However, the components regulating formation and maintenance of these neuron-glia synapses remain elusive. The transmembrane protein NG2 has been considered a potential mediator of synapse formation and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) clustering, because it contains 2 extracellular Laminin G/Neurexin/Sex Hormone-Binding Globulin domains, which in neurons are crucial for formation of transsynaptic neuroligin-neurexin complexes. NG2 is connected via Glutamate Receptor-Interacting Protein with GluA2/3-containing AMPARs, thereby possibly mediating receptor clustering in glial postsynaptic density. To elucidate the role of NG2 in neuron-glia communication, we investigated glutamatergic synaptic transmission in juvenile and aged hippocampal NG2 cells of heterozygous and homozygous NG2 knockout mice. Neuron-NG2 cell synapses readily formed in the absence of NG2. Short-term plasticity, synaptic connectivity, postsynaptic AMPAR current kinetics, and density were not affected by NG2 deletion. During development, an NG2-independent acceleration of AMPAR current kinetics and decreased synaptic connectivity were observed. Our results indicate that the lack of NG2 does not interfere with genesis and basic properties of neuron-glia synapses. In addition, we demonstrate frequent expression of neuroligins 1-3 in juvenile and aged NG2 cells, suggesting a role of these molecules in synapse formation between NG2 glia and neurons. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  15. Neto2 Assembles with Kainate Receptors in DRG Neurons during Development and Modulates Neurite Outgrowth in Adult Sensory Neurons.

    PubMed

    Vernon, Claire G; Swanson, Geoffrey T

    2017-03-22

    Peripheral sensory neurons in the dorsal root ganglia (DRG) are the initial transducers of sensory stimuli, including painful stimuli, from the periphery to central sensory and pain-processing centers. Small- to medium-diameter non-peptidergic neurons in the neonatal DRG express functional kainate receptors (KARs), one of three subfamilies of ionotropic glutamate receptors, as well as the putative KAR auxiliary subunit Neuropilin- and tolloid-like 2 (Neto2). Neto2 alters recombinant KAR function markedly but has yet to be confirmed as an auxiliary subunit that assembles with and alters the function of endogenous KARs. KARs in neonatal DRG require the GluK1 subunit as a necessary constituent, but it is unclear to what extent other KAR subunits contribute to the function and proposed roles of KARs in sensory ganglia, which include promotion of neurite outgrowth and modulation of glutamate release at the DRG-dorsal horn synapse. In addition, KARs containing the GluK1 subunit are implicated in modes of persistent but not acute pain signaling. We show here that the Neto2 protein is highly expressed in neonatal DRG and modifies KAR gating in DRG neurons in a developmentally regulated fashion in mice. Although normally at very low levels in adult DRG neurons, Neto2 protein expression can be upregulated via MEK/ERK signaling and after sciatic nerve crush and Neto2 -/- neurons from adult mice have stunted neurite outgrowth. These data confirm that Neto2 is a bona fide KAR auxiliary subunit that is an important constituent of KARs early in sensory neuron development and suggest that Neto2 assembly is critical to KAR modulation of DRG neuron process outgrowth. SIGNIFICANCE STATEMENT Pain-transducing peripheral sensory neurons of the dorsal root ganglia (DRG) express kainate receptors (KARs), a subfamily of glutamate receptors that modulate neurite outgrowth and regulate glutamate release at the DRG-dorsal horn synapse. The putative KAR auxiliary subunit Neuropilin- and

  16. Constitutive and ghrelin-dependent GHSR1a activation impairs CaV2.1 and CaV2.2 currents in hypothalamic neurons

    PubMed Central

    López Soto, Eduardo Javier; Agosti, Francina; Cabral, Agustina; Mustafa, Emilio Roman; Damonte, Valentina Martínez; Gandini, Maria Alejandra; Rodríguez, Silvia; Castrogiovanni, Daniel; Felix, Ricardo; Perelló, Mario

    2015-01-01

    The growth hormone secretagogue receptor type 1a (GHSR1a) has the highest known constitutive activity of any G protein–coupled receptor (GPCR). GHSR1a mediates the action of the hormone ghrelin, and its activation increases transcriptional and electrical activity in hypothalamic neurons. Although GHSR1a is present at GABAergic presynaptic terminals, its effect on neurotransmitter release remains unclear. The activities of the voltage-gated calcium channels, CaV2.1 and CaV2.2, which mediate neurotransmitter release at presynaptic terminals, are modulated by many GPCRs. Here, we show that both constitutive and agonist-dependent GHSR1a activity elicit a strong impairment of CaV2.1 and CaV2.2 currents in rat and mouse hypothalamic neurons and in a heterologous expression system. Constitutive GHSR1a activity reduces CaV2 currents by a Gi/o-dependent mechanism that involves persistent reduction in channel density at the plasma membrane, whereas ghrelin-dependent GHSR1a inhibition is reversible and involves altered CaV2 gating via a Gq-dependent pathway. Thus, GHSR1a differentially inhibits CaV2 channels by Gi/o or Gq protein pathways depending on its mode of activation. Moreover, we present evidence suggesting that GHSR1a-mediated inhibition of CaV2 attenuates GABA release in hypothalamic neurons, a mechanism that could contribute to neuronal activation through the disinhibition of postsynaptic neurons. PMID:26283199

  17. GDE2 regulates subtype specific motor neuron generation through inhibition of Notch signaling

    PubMed Central

    Sabharwal, Priyanka; Lee, Changhee; Park, Sungjin; Rao, Meenakshi; Sockanathan, Shanthini

    2011-01-01

    The specification of spinal interneuron and motor neuron identities initiates within progenitor cells, while motor neuron subtype diversification is regulated by hierarchical transcriptional programs implemented postmitotically. Here, we find that mice lacking GDE2, a six-transmembrane protein that triggers motor neuron generation, exhibit selective losses of distinct motor neuron subtypes, specifically in defined subsets of limb-innervating motor pools that correlate with the loss of force-generating alpha motor neurons. Mechanistically, GDE2 is expressed by postmitotic motor neurons but utilizes extracellular glycerophosphodiester phosphodiesterase activity to induce motor neuron generation by inhibiting Notch signaling in neighboring motor neuron progenitors. Thus, neuronal GDE2 controls motor neuron subtype diversity through a non cell-autonomous feedback mechanism that directly regulates progenitor cell differentiation, implying that subtype specification initiates within motor neuron progenitor populations prior to their differentiation into postmitotic motor neurons. PMID:21943603

  18. Dorsal Raphe Serotonin Neurons Mediate CO2-Induced Arousal from Sleep.

    PubMed

    Smith, Haleigh R; Leibold, Nicole K; Rappoport, Daniel A; Ginapp, Callie M; Purnell, Benton S; Bode, Nicole M; Alberico, Stephanie L; Kim, Young-Cho; Audero, Enrica; Gross, Cornelius T; Buchanan, Gordon F

    2018-02-21

    Arousal from sleep in response to CO 2 is a critical protective phenomenon. Dysregulation of CO 2 -induced arousal contributes to morbidity and mortality from prevalent diseases, such as obstructive sleep apnea and sudden infant death syndrome. Despite the critical nature of this protective reflex, the precise mechanism for CO 2 -induced arousal is unknown. Because CO 2 is a major regulator of breathing, prevailing theories suggest that activation of respiratory chemo- and mechano-sensors is required for CO 2 -induced arousal. However, populations of neurons that are not involved in the regulation of breathing are also chemosensitive. Among these are serotonin (5-HT) neurons in the dorsal raphe nucleus (DRN) that comprise a component of the ascending arousal system. We hypothesized that direct stimulation of these neurons with CO 2 could cause arousal from sleep independently of enhancing breathing. Dialysis of CO 2 -rich acidified solution into DRN, but not medullary raphe responsible for modulating breathing, caused arousal from sleep. Arousal was lost in mice with a genetic absence of 5-HT neurons, and with acute pharmacological or optogenetic inactivation of DRN 5-HT neurons. Here we demonstrate that CO 2 can cause arousal from sleep directly, without requiring enhancement of breathing, and that chemosensitive 5-HT neurons in the DRN critically mediate this arousal. Better understanding mechanisms underlying this protective reflex may lead to interventions to reduce disease-associated morbidity and mortality. SIGNIFICANCE STATEMENT Although CO 2 -induced arousal is critical to a number of diseases, the specific mechanism is not well understood. We previously demonstrated that serotonin (5-HT) neurons are important for CO 2 -induced arousal, as mice without 5-HT neurons do not arouse to CO 2 Many have interpreted this to mean that medullary 5-HT neurons that regulate breathing are important in this arousal mechanism. Here we found that direct application of CO 2

  19. Kv2 Channel Regulation of Action Potential Repolarization and Firing Patterns in Superior Cervical Ganglion Neurons and Hippocampal CA1 Pyramidal Neurons

    PubMed Central

    Liu, Pin W.

    2014-01-01

    Kv2 family “delayed-rectifier” potassium channels are widely expressed in mammalian neurons. Kv2 channels activate relatively slowly and their contribution to action potential repolarization under physiological conditions has been unclear. We explored the function of Kv2 channels using a Kv2-selective blocker, Guangxitoxin-1E (GxTX-1E). Using acutely isolated neurons, mixed voltage-clamp and current-clamp experiments were done at 37°C to study the physiological kinetics of channel gating and action potentials. In both rat superior cervical ganglion (SCG) neurons and mouse hippocampal CA1 pyramidal neurons, 100 nm GxTX-1E produced near-saturating block of a component of current typically constituting ∼60–80% of the total delayed-rectifier current. GxTX-1E also reduced A-type potassium current (IA), but much more weakly. In SCG neurons, 100 nm GxTX-1E broadened spikes and voltage clamp experiments using action potential waveforms showed that Kv2 channels carry ∼55% of the total outward current during action potential repolarization despite activating relatively late in the spike. In CA1 neurons, 100 nm GxTX-1E broadened spikes evoked from −70 mV, but not −80 mV, likely reflecting a greater role of Kv2 when other potassium channels were partially inactivated at −70 mV. In both CA1 and SCG neurons, inhibition of Kv2 channels produced dramatic depolarization of interspike voltages during repetitive firing. In CA1 neurons and some SCG neurons, this was associated with increased initial firing frequency. In all neurons, inhibition of Kv2 channels depressed maintained firing because neurons entered depolarization block more readily. Therefore, Kv2 channels can either decrease or increase neuronal excitability depending on the time scale of excitation. PMID:24695716

  20. GDE2 regulates subtype-specific motor neuron generation through inhibition of Notch signaling.

    PubMed

    Sabharwal, Priyanka; Lee, Changhee; Park, Sungjin; Rao, Meenakshi; Sockanathan, Shanthini

    2011-09-22

    The specification of spinal interneuron and motor neuron identities initiates within progenitor cells, while motor neuron subtype diversification is regulated by hierarchical transcriptional programs implemented postmitotically. Here we find that mice lacking GDE2, a six-transmembrane protein that triggers motor neuron generation, exhibit selective losses of distinct motor neuron subtypes, specifically in defined subsets of limb-innervating motor pools that correlate with the loss of force-generating alpha motor neurons. Mechanistically, GDE2 is expressed by postmitotic motor neurons but utilizes extracellular glycerophosphodiester phosphodiesterase activity to induce motor neuron generation by inhibiting Notch signaling in neighboring motor neuron progenitors. Thus, neuronal GDE2 controls motor neuron subtype diversity through a non-cell-autonomous feedback mechanism that directly regulates progenitor cell differentiation, implying that subtype specification initiates within motor neuron progenitor populations prior to their differentiation into postmitotic motor neurons. Copyright © 2011 Elsevier Inc. All rights reserved.

  1. State-dependent interactions between excitatory neuromodulators in the neuronal control of breathing

    PubMed Central

    Doi, Atsushi; Ramirez, Jan-Marino

    2010-01-01

    All neuronal networks are modulated by multiple neuropeptides and biogenic amines. Yet, few studies investigate how different modulators interact to regulate network activity. Here we explored the state-dependent functional interactions between three excitatory neuromodulators acting on neurokinin1 (NK1), alpha1 noradrenergic (α1 NE) and 5-HT2 serotonin receptors (5-HT2) within the Pre-Bötzinger complex (pre-BötC), an area critical for the generation of breathing. In anesthetized, in vivo mice the reliance on endogenous NK1 activation depended on spontaneous breathing frequency and the modulatory state of the animal. Endogenous NK1 activation had no significant respiratory effect when stimulating raphe magnus and/or locus ceruleus, but became critical, when α1 NE and 5-HT2 receptors were pharmacologically blocked. The dependence of the centrally generated respiratory rhythm on NK1 activation was blunted in the presence of α1 NE and 5-HT2 agonists as demonstrated in slices containing the pre-BötC. We conclude that a modulators’ action is determined by the concurrent modulation and interaction with other neuromodulators. Deficiencies in one neuromodulator are immediately compensated by the action of other neuromodulators. This interplay could play a role in the state-dependency of certain breathing disorders. PMID:20554877

  2. Efficient induction of dopaminergic neuron differentiation from induced pluripotent stem cells reveals impaired mitophagy in PARK2 neurons.

    PubMed

    Suzuki, Sadafumi; Akamatsu, Wado; Kisa, Fumihiko; Sone, Takefumi; Ishikawa, Kei-Ichi; Kuzumaki, Naoko; Katayama, Hiroyuki; Miyawaki, Atsushi; Hattori, Nobutaka; Okano, Hideyuki

    2017-01-29

    Patient-specific induced pluripotent stem cells (iPSCs) show promise for use as tools for in vitro modeling of Parkinson's disease. We sought to improve the efficiency of dopaminergic (DA) neuron induction from iPSCs by the using surface markers expressed in DA progenitors to increase the significance of the phenotypic analysis. By sorting for a CD184 high /CD44 - fraction during neural differentiation, we obtained a population of cells that were enriched in DA neuron precursor cells and achieved higher differentiation efficiencies than those obtained through the same protocol without sorting. This high efficiency method of DA neuronal induction enabled reliable detection of reactive oxygen species (ROS) accumulation and vulnerable phenotypes in PARK2 iPSCs-derived DA neurons. We additionally established a quantitative system using the mt-mKeima reporter system to monitor mitophagy in which mitochondria fuse with lysosomes and, by combining this system with the method of DA neuronal induction described above, determined that mitophagy is impaired in PARK2 neurons. These findings suggest that the efficiency of DA neuron induction is important for the precise detection of cellular phenotypes in modeling Parkinson's disease. Copyright © 2016. Published by Elsevier Inc.

  3. Light deprivation damages monoamine neurons and produces a depressive behavioral phenotype in rats

    PubMed Central

    Gonzalez, M. M. C.; Aston-Jones, G.

    2008-01-01

    Light is an important environmental factor for regulation of mood. There is a high frequency of seasonal affective disorder in high latitudes where light exposure is limited, and bright light therapy is a successful antidepressant treatment. We recently showed that rats kept for 6 weeks in constant darkness (DD) have anatomical and behavioral features similar to depressed patients, including dysregulation of circadian sleep–waking rhythms and impairment of the noradrenergic (NA)-locus coeruleus (LC) system. Here, we analyzed the cell viability of neural systems related to the pathophysiology of depression after DD, including NA-LC, serotoninergic-raphe nuclei and dopaminergic-ventral tegmental area neurons, and evaluated the depressive behavioral profile of light-deprived rats. We found increased apoptosis in the three aminergic systems analyzed when compared with animals maintained for 6 weeks in 12:12 light-dark conditions. The most apoptosis was observed in NA-LC neurons, associated with a significant decrease in the number of cortical NA boutons. Behaviorally, DD induced a depression-like condition as measured by increased immobility in a forced swim test (FST). DD did not appear to be stressful (no effect on adrenal or body weights) but may have sensitized responses to subsequent stressors (increased fecal number during the FST). We also found that the antidepressant desipramine decreases these neural and behavioral effects of light deprivation. These findings indicate that DD induces neural damage in monoamine brain systems and this damage is associated with a depressive behavioral phenotype. Our results suggest a mechanism whereby prolonged limited light intensity could negatively impact mood. PMID:18347342

  4. Kv7.2 regulates the function of peripheral sensory neurons.

    PubMed

    King, Chih H; Lancaster, Eric; Salomon, Daniela; Peles, Elior; Scherer, Steven S

    2014-10-01

    The Kv7 (KCNQ) family of voltage-gated K(+) channels regulates cellular excitability. The functional role of Kv7.2 has been hampered by the lack of a viable Kcnq2-null animal model. In this study, we generated homozygous Kcnq2-null sensory neurons using the Cre-Lox system; in these mice, Kv7.2 expression is absent in the peripheral sensory neurons, whereas the expression of other molecular components of nodes (including Kv7.3), paranodes, and juxtaparanodes is not altered. The conditional Kcnq2-null animals exhibit normal motor performance but have increased thermal hyperalgesia and mechanical allodynia. Whole-cell patch recording technique demonstrates that Kcnq2-null sensory neurons have increased excitability and reduced spike frequency adaptation. Taken together, our results suggest that the loss of Kv7.2 activity increases the excitability of primary sensory neurons. © 2014 Wiley Periodicals, Inc.

  5. Asynchronous Cholinergic Drive Correlates with Excitation-Inhibition Imbalance via a Neuronal Ca2+ Sensor Protein.

    PubMed

    Zhou, Keming; Cherra, Salvatore J; Goncharov, Alexandr; Jin, Yishi

    2017-05-09

    Excitation-inhibition imbalance in neural networks is widely linked to neurological and neuropsychiatric disorders. However, how genetic factors alter neuronal activity, leading to excitation-inhibition imbalance, remains unclear. Here, using the C. elegans locomotor circuit, we examine how altering neuronal activity for varying time periods affects synaptic release pattern and animal behavior. We show that while short-duration activation of excitatory cholinergic neurons elicits a reversible enhancement of presynaptic strength, persistent activation results to asynchronous and reduced cholinergic drive, inducing imbalance between endogenous excitation and inhibition. We find that the neuronal calcium sensor protein NCS-2 is required for asynchronous cholinergic release in an activity-dependent manner and dampens excitability of inhibitory neurons non-cell autonomously. The function of NCS-2 requires its Ca 2+ binding and membrane association domains. These results reveal a synaptic mechanism implicating asynchronous release in regulation of excitation-inhibition balance. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

  6. Pathophysiological role of prostaglandin E2-induced up-regulation of the EP2 receptor in motor neuron-like NSC-34 cells and lumbar motor neurons in ALS model mice.

    PubMed

    Kosuge, Yasuhiro; Miyagishi, Hiroko; Yoneoka, Yuki; Yoneda, Keiko; Nango, Hiroshi; Ishige, Kumiko; Ito, Yoshihisa

    2017-07-04

    Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease characterized by selective degeneration of motor neurons. The primary triggers for motor neuronal death are still unknown, but inflammation is considered to be an important factor contributing to the pathophysiology of ALS both clinically and in ALS models. Prostaglandin E2 (PGE2) and its corresponding four E-prostanoid receptors play a pivotal role in the degeneration of motor neurons in human and transgenic models of ALS. It has also been shown that PGE2-EP2 signaling in glial cells (astrocytes or microglia) promotes motor neuronal death in G93A mice. The present study was designed to investigate the levels of expression of EP receptors in the spinal motor neurons of ALS model mice and to examine whether PGE2 alters the expression of EP receptors in differentiated NSC-34 cells, a motor neuron-like cell line. Immunohistochemical staining demonstrated that EP2 and EP3 immunoreactivity was localized in NeuN-positive large cells showing the typical morphology of motor neurons in mice. Semi-quantitative analysis showed that the immunoreactivity of EP2 in motor neurons was significantly increased in the early symptomatic stage in ALS model mice. In contrast, the level of EP3 expression remained constant, irrespective of age. In differentiated NSC-34 cells, bath application of PGE2 resulted in a concentration-dependent decrease of MTT reduction. Although PGE2 had no effect on cell survival at concentrations of less than 10 μM, pretreatment with 10 μM PGE2 significantly up-regulated EP2 and concomitantly potentiated cell death induced by 30 μM PGE2. These results suggest that PGE2 is an important effector for induction of the EP2 subtype in differentiated NSC-34 cells, and that not only EP2 up-regulation in glial cells but also EP2 up-regulation in motor neurons plays a pivotal role in the vulnerability of motor neurons in ALS model mice. Copyright © 2017 Elsevier Ltd. All rights

  7. Angiotensin II AT1 receptors mediate neuronal sensitization and sustained blood pressure response induced by a single injection of amphetamine.

    PubMed

    Marchese, N A; Paz, M C; Caeiro, X; Dadam, F M; Baiardi, G; Perez, M F; Bregonzio, C

    2017-01-06

    A single exposure to amphetamine induces neurochemical sensitization in striatal areas. The neuropeptide angiotensin II, through AT 1 receptors (AT 1 -R) activation, is involved in these responses. However, amphetamine-induced alterations can be extended to extra-striatal areas involved in blood pressure control and their physiological outcomes. Our aim for the present study was to analyze the possible role for AT 1 -R in these events using a two-injection protocol and to further characterize the proposed AT 1 -R antagonism protocol. Central effect of orally administered AT 1 -R blocker (Candesartan, 3mg/kg p.o.×5days) in male Wistar rats was analyzed by spontaneous activity of neurons within locus coeruleus. In another group of animals pretreated with the AT 1 -R blocker or vehicle, sensitization was achieved by a single administration of amphetamine (5mg/kg i.p. - day 6) followed by a 3-week period off drug. On day 27, after receiving an amphetamine challenge (0.5mg/kg i.p.), we evaluated: (1) the sensitized c-Fos expression in locus coeruleus (LC), nucleus of the solitary tract (NTS), caudal ventrolateral medulla (A1) and central amygdala (CeAmy); and (2) the blood pressure response. AT 1 -R blockade decreased LC neurons' spontaneous firing rate. Moreover, sensitized c-Fos immunoreactivity in TH+neurons was found in LC and NTS; and both responses were blunted by the AT 1 -R blocker pretreatment. Meanwhile, no differences were found neither in CeAmy nor A1. Sensitized blood pressure response was observed as sustained changes in mean arterial pressure and was effectively prevented by AT 1 -R blockade. Our results extend AT 1 -R role in amphetamine-induced sensitization over noradrenergic nuclei and their cardiovascular output. Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.

  8. Identification of a Drosophila glucose receptor using Ca2+ imaging of single chemosensory neurons.

    PubMed

    Miyamoto, Tetsuya; Chen, Yan; Slone, Jesse; Amrein, Hubert

    2013-01-01

    Evaluation of food compounds by chemosensory cells is essential for animals to make appropriate feeding decisions. In the fruit fly Drosophila melanogaster, structurally diverse chemicals are detected by multimeric receptors composed of members of a large family of Gustatory receptor (Gr) proteins. Putative sugar and bitter receptors are expressed in distinct subsets of Gustatory Receptor Neurons (GRN) of taste sensilla, thereby assigning distinct taste qualities to sugars and bitter tasting compounds, respectively. Here we report a Ca(2+) imaging method that allows association of ligand-mediated responses to a single GRN. We find that different sweet neurons exhibit distinct response profiles when stimulated with various sugars, and likewise, different bitter neurons exhibit distinct response profiles when stimulated with a set of bitter chemicals. These observations suggest that individual neurons within a taste modality are represented by distinct repertoires of sweet and bitter taste receptors, respectively. Furthermore, we employed this novel method to identify glucose as the primary ligand for the sugar receptor Gr61a, which is not only expressed in sweet sensing neurons of classical chemosensory sensilla, but also in two supersensitive neurons of atypical taste sensilla. Thus, single cell Ca(2+) imaging can be employed as a powerful tool to identify ligands for orphan Gr proteins.

  9. GABAergic ventrolateral pre-optic nucleus neurons are involved in the mediation of the anesthetic hypnosis induced by propofol

    PubMed Central

    Yuan, Jie; Luo, Zhuxin; Zhang, Yu; Zhang, Yi; Wang, Yuan; Cao, Song; Fu, Bao; Yang, Hao; Zhang, Lin; Zhou, Wenjing; Yu, Tian

    2017-01-01

    Intravenous anesthetics have been used clinically to induce unconsciousness for seventeen decades, however the mechanism of anesthetic-induced unconsciousness remains to be fully elucidated. It has previously been demonstrated that anesthetics exert sedative effects by acting on endogenous sleep-arousal circuits. However, few studies focus on the ventrolateral pre-optic (VLPO) to locus coeruleus (LC) sleep-arousal pathway. The present study aimed to investigate if VLPO is involved in unconsciousness induced by propofol. The present study additionally investigated if the inhibitory effect of propofol on LC neurons was mediated by activating VLPO neurons. Microinjection, target lesion and extracellular single-unit recordings were used to study the role of the VLPO-LC pathway in propofol anesthesia. The results demonstrated that GABAA agonist (THIP) or GABAA antagonist (gabazine) microinjections into VLPO altered the time of loss of righting reflex and the time of recovery of righting reflex. Furthermore, propofol suppressed the spontaneous firing activity of LC noradrenergic neurons. There was no significant difference observed in firing activity between VLPO sham lesion and VLPO lesion rats. The findings indicate that VLPO neurons are important in propofol-induced unconsciousness, however are unlikely to contribute to the inhibitory effect of propofol on LC spontaneous firing activity. PMID:28765955

  10. 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

  11. 5-HT has contrasting effects in the frontal cortex, but not the hypothalamus, on changes in noradrenaline efflux induced by the monoamine releasing-agent, d-amphetamine, and the reuptake inhibitor, BTS 54 354.

    PubMed

    Géranton, Sandrine M; Heal, David J; Stanford, S Clare

    2004-03-01

    There is extensive evidence for functional interactions between central noradrenergic and serotonergic neurones. Here, dual-probe microdialysis was used in freely-moving rats to compare the effects of 5-HT on noradrenergic transmission in the rat frontal cortex and hypothalamus. We studied the effects of the 5-HT synthesis inhibitor, para-chlorophenylalanine (pCPA; which depleted 5-HT stores in both the frontal cortex and the hypothalamus), on spontaneous efflux of noradrenaline and on the noradrenergic responses to d-amphetamine, and the monoamine reuptake inhibitor, BTS 54 354. pCPA pretreatment alone did not affect spontaneous noradrenaline efflux in either brain region, whether or not alpha2-autoreceptors were inactivated by administration of the alpha2-antagonist, atipamezole (1 mg/kg i.p). However, in the frontal cortex, pCPA pretreatment augmented the amplitude of, and prolonged, the noradrenergic response to local infusion of d-amphetamine (10 microM). In contrast, pCPA abolished the increase in cortical noradrenaline efflux induced by local infusion of BTS 54 354 (50 microM). In the hypothalamus, pCPA did not affect the amplitude of the response to either of these agents but did prolong the effects of d-amphetamine on noradrenaline efflux. These findings suggest that serotonergic transmission has complex effects on the noradrenergic response to drugs that increase noradrenergic transmission in the frontal cortex, but has less influence in the hypothalamus.

  12. Cardiovascular dysautonomia in Parkinson disease: from pathophysiology to pathogenesis.

    PubMed

    Jain, Samay; Goldstein, David S

    2012-06-01

    Signs or symptoms of impaired autonomic regulation of circulation often attend Parkinson disease (PD). This review covers biomarkers and mechanisms of autonomic cardiovascular abnormalities in PD and related alpha-synucleinopathies. The clearest clinical laboratory correlate of dysautonomia in PD is loss of myocardial noradrenergic innervation, detected by cardiac sympathetic neuroimaging. About 30-40% of PD patients have orthostatic hypotension (OH), defined as a persistent, consistent fall in systolic blood pressure of at least 20 mmHg or diastolic blood pressure of at least 10 mmHg within 3 min of change in position from supine to standing. Neuroimaging evidence of cardiac sympathetic denervation is universal in PD with OH (PD+OH). In PD without OH about half the patients have diffuse left ventricular myocardial sympathetic denervation, a substantial minority have partial denervation confined to the inferolateral or apical walls, and a small number have normal innervation. Among patients with partial denervation the neuronal loss invariably progresses over time, and in those with normal innervation at least some loss eventually becomes evident. Thus, cardiac sympathetic denervation in PD occurs independently of the movement disorder. PD+OH also entails extra-cardiac noradrenergic denervation, but this is not as severe as in pure autonomic failure. PD+OH patients have failure of both the parasympathetic and sympathetic components of the arterial baroreflex. OH in PD therefore seems to reflect a "triple whammy" of cardiac and extra-cardiac noradrenergic denervation and baroreflex failure. In contrast, most patients with multiple system atrophy, which can resemble PD+OH clinically, do not have evidence for cardiac or extra-cardiac noradrenergic denervation. Catecholamines in the neuronal cytoplasm are potentially toxic, via spontaneous and enzyme-catalyzed oxidation. Normally cytoplasmic catecholamines are efficiently taken up into vesicles via the vesicular

  13. Effect of the wake-promoting agent modafinil on sleep-promoting neurons from the ventrolateral preoptic nucleus: an in vitro pharmacologic study.

    PubMed

    Gallopin, Thierry; Luppi, Pierre-Hervé; Rambert, Francis A; Frydman, Armand; Fort, Patrice

    2004-02-01

    The pharmacologic profile of modafinil, an increasingly popular wake-promoting drug for narcolepsy treatment, differs from those of classic psychostimulants such as amphetamine. However, its brain targets are still a matter of debate. We hypothesized that modafinil could increase waking by inhibiting the sleep-promoting neurons from the ventrolateral preoptic nucleus (VLPO). Such action could be direct or indirect via the potentiation of inhibition mediated by waking neurotransmitters. We thus studied the effect of modafinil on the membrane potential and firing rate of VLPO neurons recorded in rat-brain slices. We further determined whether pretreatment with modafinil modifies the effect of noradrenaline, carbachol, serotonin, histamine, dopamine, or clonidine. Pretreatment with modafinil specifically increased the inhibition of VLPO neurons induced by noradrenaline but had no effect when applied alone or in combination with other substances. Pretreatment with nisoxetine, a selective noradrenaline reuptake blocker, similarly increased the noradrenaline-induced inhibition of VLPO cells. Further, the potentiation by modafinil was minimized when modafinil and nisoxetine were applied together. These results suggest that modafinil blocks the reuptake of noradrenaline by the noradrenergic terminals on sleep-promoting neurons from the VLPO. Such a mechanism could be at least partially responsible for the wake-promoting effect of modafinil.

  14. Agonist-biased trafficking of somatostatin receptor 2A in enteric neurons.

    PubMed

    Zhao, Peishen; Canals, Meritxell; Murphy, Jane E; Klingler, Diana; Eriksson, Emily M; Pelayo, Juan-Carlos; Hardt, Markus; Bunnett, Nigel W; Poole, Daniel P

    2013-09-06

    Somatostatin (SST) 14 and SST 28 activate somatostatin 2A receptors (SSTR2A) on enteric neurons to control gut functions. SST analogs are treatments of neuroendocrine and bleeding disorders, cancer, and diarrhea, with gastrointestinal side effects of constipation, abdominal pain, and nausea. How endogenous agonists and drugs differentially regulate neuronal SSTR2A is unexplored. We evaluated SSTR2A trafficking in murine myenteric neurons and neuroendocrine AtT-20 cells by microscopy and determined whether agonist degradation by endosomal endothelin-converting enzyme 1 (ECE-1) controls SSTR2A trafficking and association with β-arrestins, key regulators of receptors. SST-14, SST-28, and peptide analogs (octreotide, lanreotide, and vapreotide) stimulated clathrin- and dynamin-mediated internalization of SSTR2A, which colocalized with ECE-1 in endosomes and the Golgi. After incubation with SST-14, SSTR2A recycled to the plasma membrane, which required active ECE-1 and an intact Golgi. SSTR2A activated by SST-28, octreotide, lanreotide, or vapreotide was retained within the Golgi and did not recycle. Although ECE-1 rapidly degraded SST-14, SST-28 was resistant to degradation, and ECE-1 did not degrade SST analogs. SST-14 and SST-28 induced transient interactions between SSTR2A and β-arrestins that were stabilized by an ECE-1 inhibitor. Octreotide induced sustained SSTR2A/β-arrestin interactions that were not regulated by ECE-1. Thus, when activated by SST-14, SSTR2A internalizes and recycles via the Golgi, which requires ECE-1 degradation of SST-14 and receptor dissociation from β-arrestins. After activation by ECE-1-resistant SST-28 and analogs, SSTR2A remains in endosomes because of sustained β-arrestin interactions. Therapeutic SST analogs are ECE-1-resistant and retain SSTR2A in endosomes, which may explain their long-lasting actions.

  15. Agonist-biased Trafficking of Somatostatin Receptor 2A in Enteric Neurons*

    PubMed Central

    Zhao, Peishen; Canals, Meritxell; Murphy, Jane E.; Klingler, Diana; Eriksson, Emily M.; Pelayo, Juan-Carlos; Hardt, Markus; Bunnett, Nigel W.; Poole, Daniel P.

    2013-01-01

    Somatostatin (SST) 14 and SST 28 activate somatostatin 2A receptors (SSTR2A) on enteric neurons to control gut functions. SST analogs are treatments of neuroendocrine and bleeding disorders, cancer, and diarrhea, with gastrointestinal side effects of constipation, abdominal pain, and nausea. How endogenous agonists and drugs differentially regulate neuronal SSTR2A is unexplored. We evaluated SSTR2A trafficking in murine myenteric neurons and neuroendocrine AtT-20 cells by microscopy and determined whether agonist degradation by endosomal endothelin-converting enzyme 1 (ECE-1) controls SSTR2A trafficking and association with β-arrestins, key regulators of receptors. SST-14, SST-28, and peptide analogs (octreotide, lanreotide, and vapreotide) stimulated clathrin- and dynamin-mediated internalization of SSTR2A, which colocalized with ECE-1 in endosomes and the Golgi. After incubation with SST-14, SSTR2A recycled to the plasma membrane, which required active ECE-1 and an intact Golgi. SSTR2A activated by SST-28, octreotide, lanreotide, or vapreotide was retained within the Golgi and did not recycle. Although ECE-1 rapidly degraded SST-14, SST-28 was resistant to degradation, and ECE-1 did not degrade SST analogs. SST-14 and SST-28 induced transient interactions between SSTR2A and β-arrestins that were stabilized by an ECE-1 inhibitor. Octreotide induced sustained SSTR2A/β-arrestin interactions that were not regulated by ECE-1. Thus, when activated by SST-14, SSTR2A internalizes and recycles via the Golgi, which requires ECE-1 degradation of SST-14 and receptor dissociation from β-arrestins. After activation by ECE-1-resistant SST-28 and analogs, SSTR2A remains in endosomes because of sustained β-arrestin interactions. Therapeutic SST analogs are ECE-1-resistant and retain SSTR2A in endosomes, which may explain their long-lasting actions. PMID:23913690

  16. Retinoic acid induction of calcium channel expression in human NT2N neurons.

    PubMed

    Gao, Z Y; Xu, G; Stwora-Wojczyk, M M; Matschinsky, F M; Lee, V M; Wolf, B A

    1998-06-18

    Ca2+ channel expression and regulation of intracellular Ca2+ homeostasis were studied during retinoic acid (RA)-induced differentiation of the human teratocarcinoma cell line Ntera 2/C1.D1 (NT2- cells) into NT2N neurons, a unique model of human neurons in culture. The cytosolic Ca2+ level of undifferentiated NT2- cells was low (75 +/- 5 nM) and stable under basal conditions, and it was only marginally decreased (by 9%) upon removal of extracellular Ca2+. After 10 microM RA treatment, NT2- cells were irreversibly differentiated into a phenotype of neuron-like NT2N cells. Cytosolic Ca2+ level of NT2N neurons was higher (106 +/- 14 nM) than that of NT2- cells and spontaneously fluctuated (0.208 +/- 0.038 transients/min) under basal conditions. Although K+ increased 86Rb fluxes in both NT2- cells and NT2N neurons, it only increased cytosolic Ca2+ level in NT2N neurons. The K+-induced increase in cytosolic Ca2+ in NT2N neurons was antagonized by 0.1-10 microM nifedipine or verapamil, 5 microM omega-CgTx GVIA, but not by 1 microM omega-agatoxin IVA, 1 microM omega-agatoxin TK, 1 microM FTX-3.3, or 100 microM Ni+ implicating L- and N-type voltage-dependent Ca2+ channels. In L- and N-type channels, but not in P- and Q-types, mRNAs were expressed in NT2N neurons as well as NT2- cells. Quantitative analysis of L- and N-type Ca2+ protein levels showed major differences between NT2- cells and NT2N neurons. In NT2- cells, N-type Ca2+ channels were undetectable while L-type channels levels were fivefold lower compared to NT2N neurons. Our findings show that L- and N-type channels are expressed during differentiation of NT2- cells into neurons, and that these voltage-dependent Ca2+ channels have a major role in regulating intracellular Ca2+ homeostasis and neuronal excitability. Copyright 1998 Academic Press.

  17. Neuronal Activation in the Central Nervous System of Rats in the Initial Stage of Chronic Kidney Disease-Modulatory Effects of Losartan and Moxonidine

    PubMed Central

    Palkovits, Miklós; Šebeková, Katarína; Klenovics, Kristina Simon; Kebis, Anton; Fazeli, Gholamreza; Bahner, Udo; Heidland, August

    2013-01-01

    The effect of mild chronic renal failure (CRF) induced by 4/6-nephrectomy (4/6NX) on central neuronal activations was investigated by c-Fos immunohistochemistry staining and compared to sham-operated rats. In the 4/6 NX rats also the effect of the angiotensin receptor blocker, losartan, and the central sympatholyticum moxonidine was studied for two months. In serial brain sections Fos-immunoreactive neurons were localized and classified semiquantitatively. In 37 brain areas/nuclei several neurons with different functional properties were strongly affected in 4/6NX. It elicited a moderate to high Fos-activity in areas responsible for the monoaminergic innervation of the cerebral cortex, the limbic system, the thalamus and hypothalamus (e.g. noradrenergic neurons of the locus coeruleus, serotonergic neurons in dorsal raphe, histaminergic neurons in the tuberomamillary nucleus). Other monoaminergic cell groups (A5 noradrenaline, C1 adrenaline, medullary raphe serotonin neurons) and neurons in the hypothalamic paraventricular nucleus (innervating the sympathetic preganglionic neurons and affecting the peripheral sympathetic outflow) did not show Fos-activity. Stress- and pain-sensitive cortical/subcortical areas, neurons in the limbic system, the hypothalamus and the circumventricular organs were also affected by 4/6NX. Administration of losartan and more strongly moxonidine modulated most effects and particularly inhibited Fos-activity in locus coeruleus neurons. In conclusion, 4/6NX elicits high activity in central sympathetic, stress- and pain-related brain areas as well as in the limbic system, which can be ameliorated by losartan and particularly by moxonidine. These changes indicate a high sensitivity of CNS in initial stages of CKD which could be causative in clinical disturbances. PMID:23818940

  18. Neuronize: a tool for building realistic neuronal cell morphologies

    PubMed Central

    Brito, Juan P.; Mata, Susana; Bayona, Sofia; Pastor, Luis; DeFelipe, Javier; Benavides-Piccione, Ruth

    2013-01-01

    This study presents a tool, Neuronize, for building realistic three-dimensional models of neuronal cells from the morphological information extracted through computer-aided tracing applications. Neuronize consists of a set of methods designed to build 3D neural meshes that approximate the cell membrane at different resolution levels, allowing a balance to be reached between the complexity and the quality of the final model. The main contribution of the present study is the proposal of a novel approach to build a realistic and accurate 3D shape of the soma from the incomplete information stored in the digitally traced neuron, which usually consists of a 2D cell body contour. This technique is based on the deformation of an initial shape driven by the position and thickness of the first order dendrites. The addition of a set of spines along the dendrites completes the model, building a final 3D neuronal cell suitable for its visualization in a wide range of 3D environments. PMID:23761740

  19. Neuronize: a tool for building realistic neuronal cell morphologies.

    PubMed

    Brito, Juan P; Mata, Susana; Bayona, Sofia; Pastor, Luis; Defelipe, Javier; Benavides-Piccione, Ruth

    2013-01-01

    This study presents a tool, Neuronize, for building realistic three-dimensional models of neuronal cells from the morphological information extracted through computer-aided tracing applications. Neuronize consists of a set of methods designed to build 3D neural meshes that approximate the cell membrane at different resolution levels, allowing a balance to be reached between the complexity and the quality of the final model. The main contribution of the present study is the proposal of a novel approach to build a realistic and accurate 3D shape of the soma from the incomplete information stored in the digitally traced neuron, which usually consists of a 2D cell body contour. This technique is based on the deformation of an initial shape driven by the position and thickness of the first order dendrites. The addition of a set of spines along the dendrites completes the model, building a final 3D neuronal cell suitable for its visualization in a wide range of 3D environments.

  20. Enhanced noradrenergic activity in the amygdala contributes to hyperarousal in an animal model of PTSD.

    PubMed

    Ronzoni, Giacomo; Del Arco, Alberto; Mora, Francisco; Segovia, Gregorio

    2016-08-01

    Increased activity of the noradrenergic system in the amygdala has been suggested to contribute to the hyperarousal symptoms associated with post-traumatic stress disorder (PTSD). However, only two studies have examined the content of noradrenaline or its metabolites in the amygdala of rats previously exposed to traumatic stress showing inconsistent results. The aim of this study was to investigate the effects of an inescapable foot shock (IFS) procedure (1) on reactivity to novelty in an open-field (as an index of hyperarousal), and (2) on noradrenaline release in the amygdala during an acute stress. To test the role of noradrenaline in amygdala, we also investigated the effects of microinjections of propranolol, a β-adrenoreceptor antagonist, and clenbuterol, a β-adrenoreceptor agonist, into the amygdala of IFS and control animals. Finally, we evaluated the expression of mRNA levels of β-adrenoreceptors (β1 and β2) in the amygdala, the hippocampus and the prefrontal cortex. Male Wistar rats (3 months) were stereotaxically implanted with bilateral guide cannulae. After recovering from surgery, animals were exposed to IFS (10 shocks, 0.86mA, and 6s per shock) and seven days later either microdialysis or microinjections were performed in amygdala. Animals exposed to IFS showed a reduced locomotion compared to non-shocked animals during the first 5min in the open-field. In the amygdala, IFS animals showed an enhanced increase of noradrenaline induced by stress compared to control animals. Bilateral microinjections of propranolol (0.5μg) into the amygdala one hour before testing in the open-field normalized the decreased locomotion observed in IFS animals. On the other hand, bilateral microinjections of clenbuterol (30ng) into the amygdala of control animals did not change the exploratory activity induced by novelty in the open field. IFS modified the mRNA expression of β1 and β2 adrenoreceptors in the prefrontal cortex and the hippocampus. These results

  1. Induction of motor neuron differentiation by transduction of Olig2 protein.

    PubMed

    Mie, Masayasu; Kaneko, Mami; Henmi, Fumiaki; Kobatake, Eiry

    2012-10-26

    Olig2 protein, a member of the basic helix-loop-helix transcription factor family, was introduced into the mouse embryonic carcinoma cell line P19 for induction of motor neuron differentiation. We show that Olig2 protein has the ability to permeate the cell membrane without the addition of a protein transduction domain (PTD), similar to other basic helix-loop-helix transcription factors such as MyoD and NeuroD2. Motor neuron differentiation was evaluated for the elongation of neurites and the expression of choline acetyltransferase (ChAT) mRNA, a differentiation marker of motor neurons. By addition of Olig2 protein, motor neuron differentiation was induced in P19 cells. Copyright © 2012 Elsevier Inc. All rights reserved.

  2. Effects of Chronic Sleep Fragmentation on Wake-Active Neurons and the Hypercapnic Arousal Response

    PubMed Central

    Li, Yanpeng; Panossian, Lori A.; Zhang, Jing; Zhu, Yan; Zhan, Guanxia; Chou, Yu-Ting; Fenik, Polina; Bhatnagar, Seema; Piel, David A.; Beck, Sheryl G.; Veasey, Sigrid

    2014-01-01

    Study Objectives: Delayed hypercapnic arousals may occur in obstructive sleep apnea. The impaired arousal response is expected to promote more pronounced oxyhemoglobin desaturations. We hypothesized that long-term sleep fragmentation (SF) results in injury to or dysfunction of wake-active neurons that manifests, in part, as a delayed hypercapnic arousal response. Design: Adult male mice were implanted for behavioral state recordings and randomly assigned to 4 weeks of either orbital platform SF (SF4wk, 30 events/h) or control conditions (Ct4wk) prior to behavioral, histological, and locus coeruleus (LC) whole cell electrophysiological evaluations. Measurements and Results: SF was successfully achieved across the 4 week study, as evidenced by a persistently increased arousal index, P < 0.01 and shortened sleep bouts, P < 0.05, while total sleep/wake times and plasma corticosterone levels were unaffected. A multiple sleep latency test performed at the onset of the dark period showed a reduced latency to sleep in SF4wk mice (P < 0.05). The hypercapnic arousal latency was increased, Ct4wk 64 ± 5 sec vs. SF4wk 154 ± 6 sec, P < 0.001, and remained elevated after a 2 week recovery (101 ± 4 sec, P < 0.001). C-fos activation in noradrenergic, orexinergic, histaminergic, and cholinergic wake-active neurons was reduced in response to hypercapnia (P < 0.05-0.001). Catecholaminergic and orexinergic projections into the cingulate cortex were also reduced in SF4wk (P < 0.01). In addition, SF4wk resulted in impaired LC neuron excitability (P < 0.01). Conclusions: Four weeks of sleep fragmentation (SF4wk) impairs arousal responses to hypercapnia, reduces wake neuron projections and locus coeruleus neuronal excitability, supporting the concepts that some effects of sleep fragmentation may contribute to impaired arousal responses in sleep apnea, which may not reverse immediately with therapy. Citation: Li Y; Panossian LA; Zhang J; Zhu Y; Zhan G; Chou YT; Fenik P; Bhatnagar S; Piel

  3. Neuronal dystonin isoform 2 is a mediator of endoplasmic reticulum structure and function.

    PubMed

    Ryan, Scott D; Ferrier, Andrew; Sato, Tadasu; O'Meara, Ryan W; De Repentigny, Yves; Jiang, Susan X; Hou, Sheng T; Kothary, Rashmi

    2012-02-01

    Dystonin/Bpag1 is a cytoskeletal linker protein whose loss of function in dystonia musculorum (dt) mice results in hereditary sensory neuropathy. Although loss of expression of neuronal dystonin isoforms (dystonin-a1/dystonin-a2) is sufficient to cause dt pathogenesis, the diverging function of each isoform and what pathological mechanisms are activated upon their loss remains unclear. Here we show that dt(27) mice manifest ultrastructural defects at the endoplasmic reticulum (ER) in sensory neurons corresponding to in vivo induction of ER stress proteins. ER stress subsequently leads to sensory neurodegeneration through induction of a proapoptotic caspase cascade. dt sensory neurons display neurodegenerative pathologies, including Ca(2+) dyshomeostasis, unfolded protein response (UPR) induction, caspase activation, and apoptosis. Isoform-specific loss-of-function analysis attributes these neurodegenerative pathologies to specific loss of dystonin-a2. Inhibition of either UPR or caspase signaling promotes the viability of cells deficient in dystonin. This study provides insight into the mechanism of dt neuropathology and proposes a role for dystonin-a2 as a mediator of normal ER structure and function.

  4. Estrogen regulates energy metabolic pathway and upstream adenosine 5'-monophosphate-activated protein kinase and phosphatase enzyme expression in dorsal vagal complex metabolosensory neurons during glucostasis and hypoglycemia.

    PubMed

    Tamrakar, Pratistha; Ibrahim, Baher A; Gujar, Amit D; Briski, Karen P

    2015-02-01

    The ability of estrogen to shield the brain from the bioenergetic insult hypoglycemia is unclear. Estradiol (E) prevents hypoglycemic activation of the energy deficit sensor adenosine 5'-monophosphate-activated protein kinase (AMPK) in hindbrain metabolosensory A2 noradrenergic neurons. This study investigates the hypothesis that estrogen regulates A2 AMPK through control of fuel metabolism and/or upstream protein kinase/phosphatase enzyme expression. A2 cells were harvested by laser microdissection after insulin or vehicle (V) injection of E- or oil (O)-implanted ovariectomized female rats. Cell lysates were evaluated by immunoblot for glycolytic, tricarboxylic acid cycle, respiratory chain, and acetyl-CoA-malonyl-CoA pathway enzymes. A2 phosphofructokinase (PFKL), isocitrate dehydrogenase, pyruvate dehydrogenase, and ATP synthase subunit profiles were elevated in E/V vs. O/V; hypoglycemia augmented PFKL and α-ketoglutarate dehydrogenase expression in E only. Hypoglycemia increased A2 Ca(2+) /calmodulin-dependent protein kinase-β in O and reduced protein phosphatase in both groups. A2 phospho-AMPK levels were equivalent in O/V vs. E/V but elevated during hypoglycemia in O only. These results implicate E in compensatory upregulation of substrate catabolism and corresponding maintenance of energy stability of A2 metabolosensory neurons during hypoglycemia, outcomes that support the potential viability of molecular substrates for hormone action as targets for therapies alleviating hypoglycemic brain injury. © 2014 Wiley Periodicals, Inc.

  5. Exercise offers anxiolytic potential: A role for stress and brain noradrenergic-galaninergic mechanisms

    PubMed Central

    Sciolino, Natale R.; Holmes, Philip V.

    2016-01-01

    Although physical activity reduces anxiety in humans, the neural basis for this response is unclear. Rodent models are essential to understand the mechanisms that underlie the benefits of exercise. However, it is controversial whether exercise exerts anxiolytic-like potential in rodents. Evidence is reviewed to evaluate the effects of wheel running, an experimental mode of exercise in rodents, on behavior in tests of anxiety and on norepinephrine and galanin systems in neural circuits that regulate stress. Stress is proposed to account for mixed behavioral findings in this literature. Indeed, running promotes an adaptive response to stress and alters anxiety-like behaviors in a manner dependent on stress. Running amplifies galanin expression in noradrenergic locus coeruleus (LC) and suppresses stress-induced activity of the LC and norepinephrine output in LC-target regions. Thus, enhanced galanin-mediated suppression of brain norepinephrine in runners is supported by current literature as a mechanism that may contribute to the stress-protective effects of exercise. These data support the use of rodents to study the emotional and neurobiological consequences of exercise. PMID:22771334

  6. Stimulation of postsynapse adrenergic α2A receptor improves attention/cognition performance in an animal model of attention deficit hyperactivity disorder.

    PubMed

    Kawaura, Kazuaki; Karasawa, Jun-ichi; Chaki, Shigeyuki; Hikichi, Hirohiko

    2014-08-15

    A 5-trial inhibitory avoidance test using spontaneously hypertensive rat (SHR) pups has been used as an animal model of attention deficit hyperactivity disorder (ADHD). However, the roles of noradrenergic systems, which are involved in the pathophysiology of ADHD, have not been investigated in this model. In the present study, the effects of adrenergic α2 receptor stimulation, which has been an effective treatment for ADHD, on attention/cognition performance were investigated in this model. Moreover, neuronal mechanisms mediated through adrenergic α2 receptors were investigated. We evaluated the effects of both clonidine, a non-selective adrenergic α2 receptor agonist, and guanfacine, a selective adrenergic α2A receptor agonist, using a 5-trial inhibitory avoidance test with SHR pups. Juvenile SHR exhibited a shorter transfer latency, compared with juvenile Wistar Kyoto (WKY) rats. Both clonidine and guanfacine significantly prolonged the transfer latency of juvenile SHR. The effects of clonidine and guanfacine were significantly blocked by pretreatment with an adrenergic α2A receptor antagonist. In contrast, the effect of clonidine was not attenuated by pretreatment with an adrenergic α2B receptor antagonist, or an adrenergic α2C receptor antagonist, while it was attenuated by a non-selective adrenergic α2 receptor antagonist. Furthermore, the effects of neither clonidine nor guanfacine were blocked by pretreatment with a selective noradrenergic neurotoxin. These results suggest that the stimulation of the adrenergic α2A receptor improves the attention/cognition performance of juvenile SHR in the 5-trial inhibitory avoidance test and that postsynaptic, rather than presynaptic, adrenergic α2A receptor is involved in this effect. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. VMAT2-Mediated Neurotransmission from Midbrain Leptin Receptor Neurons in Feeding Regulation

    PubMed Central

    Lu, Yungang; Xu, Pingwen; Isingrini, Elsa; Xu, Yong

    2017-01-01

    Abstract Leptin receptors (LepRs) expressed in the midbrain contribute to the action of leptin on feeding regulation. The midbrain neurons release a variety of neurotransmitters including dopamine (DA), glutamate and GABA. However, which neurotransmitter mediates midbrain leptin action on feeding remains unclear. Here, we showed that midbrain LepR neurons overlap with a subset of dopaminergic, GABAergic and glutamatergic neurons. Specific removal of vesicular monoamine transporter 2 (VMAT2) in midbrain LepR neurons (KO mice) disrupted DA accumulation in vesicles, but failed to cause a significant change in the evoked release of either glutamate or GABA to downstream neurons. While KO mice showed no differences on chow, they presented a reduced high-fat diet (HFD) intake and resisted to HFD-induced obesity. Specific activation of midbrain LepR neurons promoted VMAT2-dependent feeding on chow and HFD. When tested with an intermittent access to HFD where first 2.5-h HFD eating (binge-like) and 24-h HFD feeding were measured, KO mice exhibited more binge-like, but less 24-h HFD feeding. Interestingly, leptin inhibited 24-h HFD feeding in controls but not in KO mice. Thus, VMAT2-mediated neurotransmission from midbrain LepR neurons contributes to both binge-like eating and HFD feeding regulation. PMID:28560316

  8. Loss of MeCP2 From Forebrain Excitatory Neurons Leads to Cortical Hyperexcitation and Seizures

    PubMed Central

    Zhang, Wen; Peterson, Matthew; Beyer, Barbara; Frankel, Wayne N.

    2014-01-01

    Mutations of MECP2 cause Rett syndrome (RTT), a neurodevelopmental disorder leading to loss of motor and cognitive functions, impaired social interactions, and seizure at young ages. Defects of neuronal circuit development and function are thought to be responsible for the symptoms of RTT. The majority of RTT patients show recurrent seizures, indicating that neuronal hyperexcitation is a common feature of RTT. However, mechanisms underlying hyperexcitation in RTT are poorly understood. Here we show that deletion of Mecp2 from cortical excitatory neurons but not forebrain inhibitory neurons in the mouse leads to spontaneous seizures. Selective deletion of Mecp2 from excitatory but not inhibitory neurons in the forebrain reduces GABAergic transmission in layer 5 pyramidal neurons in the prefrontal and somatosensory cortices. Loss of MeCP2 from cortical excitatory neurons reduces the number of GABAergic synapses in the cortex, and enhances the excitability of layer 5 pyramidal neurons. Using single-cell deletion of Mecp2 in layer 2/3 pyramidal neurons, we show that GABAergic transmission is reduced in neurons without MeCP2, but is normal in neighboring neurons with MeCP2. Together, these results suggest that MeCP2 in cortical excitatory neurons plays a critical role in the regulation of GABAergic transmission and cortical excitability. PMID:24523563

  9. Noradrenergic facilitation of shock-probe defensive burying in lateral septum of rats, and modulation by chronic treatment with desipramine.

    PubMed

    Bondi, Corina O; Barrera, Gabriel; Lapiz, M Danet S; Bedard, Tania; Mahan, Amy; Morilak, David A

    2007-03-30

    We have previously shown that acute stress-induced release of norepinephrine (NE) facilitates anxiety-like behavioral responses to stress, such as reduction in open-arm exploration on the elevated-plus maze and in social behavior on the social interaction test. Since these responses represent inhibition of ongoing behavior, it is important to also address whether NE facilitates a response that represents an activation of behavior. Correspondingly, it is unknown how a chronic elevation in tonic steady-state noradrenergic (NA) neurotransmission induced by NE reuptake blockade might alter this acute modulatory function, a regulatory process that may be pertinent to the anxiolytic effects of NE reuptake blockers such as desipramine (DMI). Therefore, in this study, we investigated noradrenergic modulation of the shock-probe defensive burying response in the lateral septum (LS). In experiment 1, shock-probe exposure induced an acute 3-fold increase in NE levels measured in LS of male Sprague-Dawley rats by microdialysis. Shock-probe exposure also induced a modest rise in plasma ACTH, taken as an indicator of perceived stress, that returned to baseline more rapidly in rats that were allowed to bury the probe compared to rats prevented from burying by providing them with minimal bedding, indicating that the active defensive burying behavior is an effective coping strategy that reduces the impact of acute shock probe-induced stress. In experiment 2, blockade of either alpha(1)- or beta-adrenergic receptors in LS by local antagonist microinjection immediately before testing reduced defensive burying and increased immobility. In the next experiment, chronic DMI treatment increased basal extracellular NE levels in LS, and attenuated the acute shock probe-induced increase in NE release in LS relative to baseline. Chronic DMI treatment decreased shock-probe defensive burying behavior in a time-dependent manner, apparent only after 2 weeks or more of drug treatment. Moreover

  10. Noradrenergic Regulation of Central Amygdala in Aversive Pavlovian-to-Instrumental Transfer

    PubMed Central

    Soroeta, Jose M.

    2017-01-01

    Abstract The neural mechanisms through which a Pavlovian conditioned stimulus (CS) elicits innate defense responses are well understood. But a Pavlovian CS can also invigorate ongoing instrumental responding, as shown by studies of aversive Pavlovian-to-instrumental transfer (PIT). While the neural circuitry of appetitive PIT has been studied extensively, little is known about the brain mechanisms of aversive PIT. We recently showed the central amygdala (CeA) is essential for aversive PIT. In the current studies, using pharmacology and designer receptors in rodents, we demonstrate that noradrenergic (NE) activity negatively regulates PIT via brainstem locus coeruleus (LC) activity and LC projections to CeA. Our results provide evidence for a novel pathway through which response modulation occurs between brainstem neuromodulatory systems and CeA to invigorate adaptive behavior in the face of threat. PMID:29071299

  11. Robo2 determines subtype-specific axonal projections of trigeminal sensory neurons

    PubMed Central

    Pan, Y. Albert; Choy, Margaret; Prober, David A.; Schier, Alexander F.

    2012-01-01

    How neurons connect to form functional circuits is central to the understanding of the development and function of the nervous system. In the somatosensory system, perception of sensory stimuli to the head requires specific connections between trigeminal sensory neurons and their many target areas in the central nervous system. Different trigeminal subtypes have specialized functions and downstream circuits, but it has remained unclear how subtype-specific axonal projection patterns are formed. Using zebrafish as a model system, we followed the development of two trigeminal sensory neuron subtypes: one that expresses trpa1b, a nociceptive channel important for sensing environmental chemicals; and a distinct subtype labeled by an islet1 reporter (Isl1SS). We found that Trpa1b and Isl1SS neurons have overall similar axon trajectories but different branching morphologies and distributions of presynaptic sites. Compared with Trpa1b neurons, Isl1SS neurons display reduced branch growth and synaptogenesis at the hindbrain-spinal cord junction. The subtype-specific morphogenesis of Isl1SS neurons depends on the guidance receptor Robo2. robo2 is preferentially expressed in the Isl1SS subset and inhibits branch growth and synaptogenesis. In the absence of Robo2, Isl1SS afferents acquire many of the characteristics of Trpa1b afferents. These results reveal that subtype-specific activity of Robo2 regulates subcircuit morphogenesis in the trigeminal sensory system. PMID:22190641

  12. Vagal innervation of the aldosterone-sensitive HSD2 neurons in the NTS

    PubMed Central

    Shin, Jung-Won; Geerling, Joel C.; Loewy, Arthur D.

    2009-01-01

    The nucleus of the solitary tract (NTS) contains a unique subpopulation of aldosterone-sensitive neurons. These neurons express the enzyme 11-β-hydroxysteroid dehydrogenase type 2 (HSD2) and are activated by sodium deprivation. They are located in the caudal NTS, a region which is densely innervated by the vagus nerve, suggesting that they could receive direct viscerosensory input from the periphery. To test this possibility, we injected the highly sensitive axonal tracer biotinylated dextran amine (BDA) into the left nodose ganglion in rats. Using confocal microscopy, we observed a sparse input from the vagus to most HSD2 neurons. Roughly 80% of the ipsilateral HSD2 neurons exhibited at least one close contact with a BDA-labeled vagal bouton, although most of these cells received only a few total contacts. Most of these contacts were axo-dendritic (~80%), while ~20% were axo-somatic. In contrast, the synaptic vesicular transporters VGLUT2 or GAD7 labeled much larger populations of boutons contacting HSD2-labeled dendrites and somata, suggesting that direct input from the vagus may only account for a minority of the information integrated by these neurons. In summary, the aldosterone-sensitive HSD2 neurons in the NTS appear to receive a small amount of direct viscerosensory input from the vagus nerve. The peripheral sites of origin and functional significance of this projection remain unknown. Combined with previously-identified central sources of input to these cells, the present finding indicates that the HSD2 neurons integrate humoral information with input from a variety of neural afferents. PMID:19010311

  13. Oxidative metabolism and Ca2+ handling in isolated brain mitochondria and striatal neurons from R6/2 mice, a model of Huntington's disease.

    PubMed

    Hamilton, James; Pellman, Jessica J; Brustovetsky, Tatiana; Harris, Robert A; Brustovetsky, Nickolay

    2016-07-01

    Alterations in oxidative metabolism and defects in mitochondrial Ca 2+ handling have been implicated in the pathology of Huntington's disease (HD), but existing data are contradictory. We investigated the effect of human mHtt fragments on oxidative metabolism and Ca 2+ handling in isolated brain mitochondria and cultured striatal neurons from the R6/2 mouse model of HD. Non-synaptic and synaptic mitochondria isolated from the brains of R6/2 mice had similar respiratory rates and Ca 2+ uptake capacity compared with mitochondria from wild-type (WT) mice. Respiratory activity of cultured striatal neurons measured with Seahorse XF24 flux analyzer revealed unaltered cellular respiration in neurons derived from R6/2 mice compared with neurons from WT animals. Consistent with the lack of respiratory dysfunction, ATP content of cultured striatal neurons from R6/2 and WT mice was similar. Mitochondrial Ca 2+ accumulation was also evaluated in cultured striatal neurons from R6/2 and WT animals. Our data obtained with striatal neurons derived from R6/2 and WT mice show that both glutamate-induced increases in cytosolic Ca 2+ and subsequent carbonilcyanide p-triflouromethoxyphenylhydrazone-induced increases in cytosolic Ca 2+ were similar between WT and R6/2, suggesting that mitochondria in neurons derived from both types of animals accumulated comparable amounts of Ca 2+ Overall, our data argue against respiratory deficiency and impaired Ca 2+ handling induced by human mHtt fragments in both isolated brain mitochondria and cultured striatal neurons from transgenic R6/2 mice. © The Author 2016. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  14. Aging and amyloid β oligomers enhance TLR4 expression, LPS-induced Ca2+ responses, and neuron cell death in cultured rat hippocampal neurons.

    PubMed

    Calvo-Rodríguez, María; de la Fuente, Carmen; García-Durillo, Mónica; García-Rodríguez, Carmen; Villalobos, Carlos; Núñez, Lucía

    2017-01-31

    Toll-like receptors (TLRs) are transmembrane pattern-recognition receptors of the innate immune system recognizing diverse pathogen-derived and tissue damage-related ligands. It has been suggested that TLR signaling contributes to the pathogenesis of age-related, neurodegenerative diseases, including Alzheimer's disease (AD). AD is associated to oligomers of the amyloid β peptide (Aβo) that cause intracellular Ca 2+ dishomeostasis and neuron cell death in rat hippocampal neurons. Here we assessed the interplay between inflammation and Aβo in long-term cultures of rat hippocampal neurons, an in vitro model of neuron aging and/or senescence. Ca 2+ imaging and immunofluorescence against annexin V and TLR4 were applied in short- and long-term cultures of rat hippocampal neurons to test the effects of TLR4-agonist LPS and Aβo on cytosolic [Ca 2+ ] and on apoptosis as well as on expression of TLR4. LPS increases cytosolic [Ca 2+ ] and promotes apoptosis in rat hippocampal neurons in long-term culture considered aged and/or senescent neurons, but not in short-term cultured neurons considered young neurons. TLR4 antagonist CAY10614 prevents both effects. TLR4 expression in rat hippocampal neurons is significantly larger in aged hippocampal cultures. Treatment of aged hippocampal cultures with Aβo increases TLR4 expression and enhances LPS-induced Ca 2+ responses and neuron cell death. Aging and amyloid β oligomers, the neurotoxin involved in Alzheimer's disease, enhance TLR4 expression as well as LPS-induced Ca 2+ responses and neuron cell death in rat hippocampal neurons aged in vitro.

  15. Noradrenergic innervation of the hypothalamus of rhesus monkeys: distribution of dopamine-beta-hydroxylase immunoreactive fibers and quantitative analysis of varicosities in the paraventricular nucleus.

    PubMed

    Ginsberg, S D; Hof, P R; Young, W G; Morrison, J H

    1993-01-22

    the paraventricular nucleus of the hypothalamus. The methodology employed in this study allowed for the high resolution of immunoreactive profiles through the volume of tissue being analyzed, and was more accurate than conventional light microscopy in terms of varicosity quantification. Quantitatively, a significant difference in the density of dopamine-beta-hydroxylase-immunoreactive varicosities was found between magnocellular and parvicellular regions, suggesting that parvicellular neurons received a denser noradrenergic input. These differential patterns may reflect an important functional role for norepinephrine in the regulation of anterior pituitary secretion through the hypothalamic-pituitary-adrenal stress axis.

  16. 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

  17. Amygdala EphB2 Signaling Regulates Glutamatergic Neuron Maturation and Innate Fear.

    PubMed

    Zhu, Xiao-Na; Liu, Xian-Dong; Zhuang, Hanyi; Henkemeyer, Mark; Yang, Jing-Yu; Xu, Nan-Jie

    2016-09-28

    The amygdala serves as emotional center to mediate innate fear behaviors that are reflected through neuronal responses to environmental aversive cues. However, the molecular mechanism underlying the initial neuron responses is poorly understood. In this study, we monitored the innate defensive responses to aversive stimuli of either elevated plus maze or predator odor in juvenile mice and found that glutamatergic neurons were activated in amygdala. Loss of EphB2, a receptor tyrosine kinase expressed in amygdala neurons, suppressed the reactions and led to defects in spine morphogenesis and fear behaviors. We further found a coupling of spinogenesis with these threat cues induced neuron activation in developing amygdala that was controlled by EphB2. A constitutively active form of EphB2 was sufficient to rescue the behavioral and morphological defects caused by ablation of ephrin-B3, a brain-enriched ligand to EphB2. These data suggest that kinase-dependent EphB2 intracellular signaling plays a major role for innate fear responses during the critical developing period, in which spinogenesis in amygdala glutamatergic neurons was involved. Generation of innate fear responses to threat as an evolutionally conserved brain feature relies on development of functional neural circuit in amygdala, but the molecular mechanism remains largely unknown. We here identify that EphB2 receptor tyrosine kinase, which is specifically expressed in glutamatergic neurons, is required for the innate fear responses in the neonatal brain. We further reveal that EphB2 mediates coordination of spinogenesis and neuron activation in amygdala during the critical period for the innate fear. EphB2 catalytic activity plays a major role for the behavior upon EphB-ephrin-B3 binding and transnucleus neuronal connections. Our work thus indicates an essential synaptic molecular signaling within amygdala that controls synapse development and helps bring about innate fear emotions in the postnatal

  18. Amygdala EphB2 Signaling Regulates Glutamatergic Neuron Maturation and Innate Fear

    PubMed Central

    Zhu, Xiao-Na; Liu, Xian-Dong; Zhuang, Hanyi; Henkemeyer, Mark

    2016-01-01

    The amygdala serves as emotional center to mediate innate fear behaviors that are reflected through neuronal responses to environmental aversive cues. However, the molecular mechanism underlying the initial neuron responses is poorly understood. In this study, we monitored the innate defensive responses to aversive stimuli of either elevated plus maze or predator odor in juvenile mice and found that glutamatergic neurons were activated in amygdala. Loss of EphB2, a receptor tyrosine kinase expressed in amygdala neurons, suppressed the reactions and led to defects in spine morphogenesis and fear behaviors. We further found a coupling of spinogenesis with these threat cues induced neuron activation in developing amygdala that was controlled by EphB2. A constitutively active form of EphB2 was sufficient to rescue the behavioral and morphological defects caused by ablation of ephrin-B3, a brain-enriched ligand to EphB2. These data suggest that kinase-dependent EphB2 intracellular signaling plays a major role for innate fear responses during the critical developing period, in which spinogenesis in amygdala glutamatergic neurons was involved. SIGNIFICANCE STATEMENT Generation of innate fear responses to threat as an evolutionally conserved brain feature relies on development of functional neural circuit in amygdala, but the molecular mechanism remains largely unknown. We here identify that EphB2 receptor tyrosine kinase, which is specifically expressed in glutamatergic neurons, is required for the innate fear responses in the neonatal brain. We further reveal that EphB2 mediates coordination of spinogenesis and neuron activation in amygdala during the critical period for the innate fear. EphB2 catalytic activity plays a major role for the behavior upon EphB–ephrin-B3 binding and transnucleus neuronal connections. Our work thus indicates an essential synaptic molecular signaling within amygdala that controls synapse development and helps bring about innate fear emotions

  19. Hindbrain medulla catecholamine cell group involvement in lactate-sensitive hypoglycemia-associated patterns of hypothalamic norepinephrine and epinephrine activity.

    PubMed

    Shrestha, P K; Tamrakar, P; Ibrahim, B A; Briski, K P

    2014-10-10

    Cell-type compartmentation of glucose metabolism in the brain involves trafficking of the oxidizable glycolytic end product, l-lactate, by astrocytes to fuel neuronal mitochondrial aerobic respiration. Lactate availability within the hindbrain medulla is a monitored function that regulates systemic glucostasis as insulin-induced hypoglycemia (IIH) is exacerbated by lactate repletion of that brain region. A2 noradrenergic neurons are a plausible source of lactoprivic input to the neural gluco-regulatory circuit as caudal fourth ventricular (CV4) lactate infusion normalizes IIH-associated activation, e.g. phosphorylation of the high-sensitivity energy sensor, adenosine 5'-monophosphate-activated protein kinase (AMPK), in these cells. Here, we investigated the hypothesis that A2 neurons are unique among medullary catecholamine cells in directly screening lactate-derived energy. Adult male rats were injected with insulin or vehicle following initiation of continuous l-lactate infusion into the CV4. Two hours after injections, A1, C1, A2, and C2 neurons were collected by laser-microdissection for Western blot analysis of AMPKα1/2 and phosphoAMPKα1/2 proteins. Results show that AMPK is expressed in each cell group, but only a subset, e.g. A1, C1, and A2 neurons, exhibit increased sensor activity in response to IIH. Moreover, hindbrain lactate repletion reversed hypoglycemic augmentation of pAMPKα1/2 content in A2 and C1 but not A1 cells, and normalized hypothalamic norepinephrine and epinephrine content in a site-specific manner. The present evidence for discriminative reactivity of AMPK-expressing medullary catecholamine neurons to the screened energy substrate lactate implies that that lactoprivation is selectively signaled to the hypothalamus by A2 noradrenergic and C1 adrenergic cells. Copyright © 2014 IBRO. Published by Elsevier Ltd. All rights reserved.

  20. TRPV2, a capsaicin receptor homologue, is expressed predominantly in the neurotrophin-3-dependent subpopulation of primary sensory neurons.

    PubMed

    Tamura, S; Morikawa, Y; Senba, E

    2005-01-01

    TRPV2, a member of transient receptor potential ion channels, responds to high-threshold noxious heat, but neither to capsaicin nor to proton. Although TRPV2 is expressed in medium- to large-sized dorsal root ganglion (DRG) neurons with myelinated fibers in adult rodents, little is known about the neurotrophin dependence of TRPV2-positive neurons in the developing and adult DRGs of mice. In the present study, using immunohistochemistry, we found that TRPV2 was first expressed in DRG neurons at embryonic day (E) 11.5, when neither TRPV1 nor TRPM8 was detected yet. Double-immunofluorescence staining revealed that tyrosine kinase receptor C (TrkC) was expressed in most of TRPV2-positive DRG neurons at E11.5 and E13.5. In addition, the percentage of TRPV2-positive neurons in the total DRG neurons at E13.5 reached the same as that of adulthood. In adult DRGs, TrkC and Ret were expressed in 68% and 25% of TRPV2-positive neurons, respectively. These results suggest that TRPV2 is expressed predominantly in the NT-3-dependent subpopulation of DRG neurons throughout development and in adult mice.

  1. A Store-Operated Ca2+ Influx Pathway in the Bag Cell Neurons of Aplysia

    PubMed Central

    Kachoei, Babak A.; Knox, Ronald J.; Uthuza, Didier; Levy, Simon; Kaczmarek, Leonard K.; Magoski, Neil S.

    2010-01-01

    Although store-operated Ca2+ influx has been well-studied in nonneuronal cells, an understanding of its nature in neurons remains poor. In the bag cell neurons of Aplysia californica, prior work has suggested that a Ca2+ entry pathway can be activated by Ca2+ store depletion. Using fura-based imaging of intracellular Ca2+ in cultured bag cell neurons, we now characterize this pathway as store-operated Ca2+ influx. In the absence of extracellular Ca2+, the endoplasmic reticulum Ca2+-ATPase inhibitors, cyclopiazonic acid (CPA) or thapsigargin, depleted intracellular stores and elevated intracellular free Ca2+. With the subsequent addition of extracellular Ca2+, a prominent Ca2+ influx was observed. The ryanodine receptor agonist, chloroethylphenol (CEP), also increased intracellular Ca2+ but did not initiate store-operated Ca2+ influx, despite overlap between CEP- and CPA-sensitive stores. Bafilomycin A, a vesicular H+-ATPase inhibitor, liberated intracellular Ca2+ from acidic stores and attenuated subsequent Ca2+ influx, presumably by replenishing CPA-depleted stores. Store-operated Ca2+ influx was partially blocked by low concentrations of La3+ or BTP2, and strongly inhibited by either 1-[b-[3-(4-methoxyphenyl)propoxy]-4-methoxyphenethyl]-1H-imidazole (SKF-96365) or a high concentration of Ni2+. Regarding IP3 receptor blockers, 2-aminoethyldiphenyl borate, but not xestospongin C, prevented store-operated Ca2+ influx. However, jasplakinolide, an actin stabilizer reported to inhibit this pathway in smooth muscle cell lines, was ineffective. The bag cell neurons initiate reproductive behavior through a prolonged afterdischarge associated with intracellular Ca2+ release and neuropeptide secretion. Store-operated Ca2+ influx may serve to replenish stores depleted during the afterdischarge or participate in the release of peptide that triggers behavior. PMID:16885525

  2. A critical role for Piezo2 channels in the mechanotransduction of mouse proprioceptive neurons

    PubMed Central

    Florez-Paz, Danny; Bali, Kiran Kumar; Kuner, Rohini; Gomis, Ana

    2016-01-01

    Proprioceptors are responsible for the conscious sensation of limb position and movement, muscle tension or force, and balance. Recent evidence suggests that Piezo2 is a low threshold mechanosensory receptor in the peripheral nervous system, acting as a transducer for touch sensation and proprioception. Thus, we characterized proprioceptive neurons in the mesencephalic trigeminal nucleus that are involved in processing proprioceptive information from the face and oral cavity. This is a specific population of neurons that produce rapidly adapting mechanically-activated currents that are fully dependent on Piezo2. As such, we analyzed the deficits in balance and coordination caused by the selective deletion of the channel in proprioceptors (conditional knockout). The data clearly shows that Piezo2 fulfills a critical role in a defined homogeneous population of proprioceptor neurons that innervate the head muscles, demonstrating that this ion channel is essential for mammalian proprioceptive mechanotransduction. PMID:27184818

  3. Alpha-2 agonist attenuates ischemic injury in spinal cord neurons.

    PubMed

    Freeman, Kirsten A; Puskas, Ferenc; Bell, Marshall T; Mares, Joshua M; Foley, Lisa S; Weyant, Michael J; Cleveland, Joseph C; Fullerton, David A; Meng, Xianzhong; Herson, Paco S; Reece, T Brett

    2015-05-01

    Paraplegia secondary to spinal cord ischemia-reperfusion injury remains a devastating complication of thoracoabdominal aortic intervention. The complex interactions between injured neurons and activated leukocytes have limited the understanding of neuron-specific injury. We hypothesize that spinal cord neuron cell cultures subjected to oxygen-glucose deprivation (OGD) would simulate ischemia-reperfusion injury, which could be attenuated by specific alpha-2a agonism in an Akt-dependent fashion. Spinal cords from perinatal mice were harvested, and neurons cultured in vitro for 7-10 d. Cells were pretreated with 1 μM dexmedetomidine (Dex) and subjected to OGD in an anoxic chamber. Viability was determined by MTT assay. Deoxyuridine-triphosphate nick-end labeling staining and lactate dehydrogenase (LDH) assay were used for apoptosis and necrosis identification, respectively. Western blot was used for protein analysis. Vehicle control cells were only 59% viable after 1 h of OGD. Pretreatment with Dex significantly preserves neuronal viability with 88% viable (P < 0.05). Dex significantly decreased apoptotic cells compared with that of vehicle control cells by 50% (P < 0.05). Necrosis was not significantly different between treatment groups. Mechanistically, Dex treatment significantly increased phosphorylated Akt (P < 0.05), but protective effects of Dex were eliminated by an alpha-2a antagonist or Akt inhibitor (P < 0.05). Using a novel spinal cord neuron cell culture, OGD mimics neuronal metabolic derangement responsible for paraplegia after aortic surgery. Dex preserves neuronal viability and decreases apoptosis in an Akt-dependent fashion. Dex demonstrates clinical promise for reducing the risk of paraplegia after high-risk aortic surgery. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. Noradrenaline Modulates the Membrane Potential and Holding Current of Medial Prefrontal Cortex Pyramidal Neurons via β1-Adrenergic Receptors and HCN Channels.

    PubMed

    Grzelka, Katarzyna; Kurowski, Przemysław; Gawlak, Maciej; Szulczyk, Paweł

    2017-01-01

    The medial prefrontal cortex (mPFC) receives dense noradrenergic projections from the locus coeruleus. Adrenergic innervation of mPFC pyramidal neurons plays an essential role in both physiology (control of memory formation, attention, working memory, and cognitive behavior) and pathophysiology (attention deficit hyperactivity disorder, posttraumatic stress disorder, cognitive deterioration after traumatic brain injury, behavioral changes related to addiction, Alzheimer's disease and depression). The aim of this study was to elucidate the mechanism responsible for adrenergic receptor-mediated control of the resting membrane potential in layer V mPFC pyramidal neurons. The membrane potential or holding current of synaptically isolated layer V mPFC pyramidal neurons was recorded in perforated-patch and classical whole-cell configurations in slices from young rats. Application of noradrenaline (NA), a neurotransmitter with affinity for all types of adrenergic receptors, evoked depolarization or inward current in the tested neurons irrespective of whether the recordings were performed in the perforated-patch or classical whole-cell configuration. The effect of noradrenaline depended on β 1 - and not α 1 - or α 2 -adrenergic receptor stimulation. Activation of β 1 -adrenergic receptors led to an increase in inward Na + current through hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, which carry a mixed Na + /K + current. The protein kinase A- and C-, glycogen synthase kinase-3β- and tyrosine kinase-linked signaling pathways were not involved in the signal transduction between β 1 -adrenergic receptors and HCN channels. The transduction system operated in a membrane-delimited fashion and involved the βγ subunit of G-protein. Thus, noradrenaline controls the resting membrane potential and holding current in mPFC pyramidal neurons through β 1 -adrenergic receptors, which in turn activate HCN channels via a signaling pathway involving the

  5. Noradrenaline Modulates the Membrane Potential and Holding Current of Medial Prefrontal Cortex Pyramidal Neurons via β1-Adrenergic Receptors and HCN Channels

    PubMed Central

    Grzelka, Katarzyna; Kurowski, Przemysław; Gawlak, Maciej; Szulczyk, Paweł

    2017-01-01

    The medial prefrontal cortex (mPFC) receives dense noradrenergic projections from the locus coeruleus. Adrenergic innervation of mPFC pyramidal neurons plays an essential role in both physiology (control of memory formation, attention, working memory, and cognitive behavior) and pathophysiology (attention deficit hyperactivity disorder, posttraumatic stress disorder, cognitive deterioration after traumatic brain injury, behavioral changes related to addiction, Alzheimer’s disease and depression). The aim of this study was to elucidate the mechanism responsible for adrenergic receptor-mediated control of the resting membrane potential in layer V mPFC pyramidal neurons. The membrane potential or holding current of synaptically isolated layer V mPFC pyramidal neurons was recorded in perforated-patch and classical whole-cell configurations in slices from young rats. Application of noradrenaline (NA), a neurotransmitter with affinity for all types of adrenergic receptors, evoked depolarization or inward current in the tested neurons irrespective of whether the recordings were performed in the perforated-patch or classical whole-cell configuration. The effect of noradrenaline depended on β1- and not α1- or α2-adrenergic receptor stimulation. Activation of β1-adrenergic receptors led to an increase in inward Na+ current through hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, which carry a mixed Na+/K+ current. The protein kinase A- and C-, glycogen synthase kinase-3β- and tyrosine kinase-linked signaling pathways were not involved in the signal transduction between β1-adrenergic receptors and HCN channels. The transduction system operated in a membrane-delimited fashion and involved the βγ subunit of G-protein. Thus, noradrenaline controls the resting membrane potential and holding current in mPFC pyramidal neurons through β1-adrenergic receptors, which in turn activate HCN channels via a signaling pathway involving the βγ subunit. PMID

  6. Thrombospondin-4 Promotes Neuronal Differentiation of NG2 Cells via the ERK/MAPK Pathway.

    PubMed

    Yang, Hai Jie; Ma, Shuang Ping; Ju, Fei; Zhang, Ya Ping; Li, Zhi Chao; Zhang, Bin Bin; Lian, Jun Jiang; Wang, Lei; Cheng, Bin Feng; Wang, Mian; Feng, Zhi Wei

    2016-12-01

    NG2-expressing neural progenitors can produce neurons in the central nervous system, providing a potential cell resource of therapy for neurological disorders. However, the mechanism underlying neuronal differentiation of NG2 cells remains largely unknown. In this report, we found that a thrombospondin (TSP) family member, TSP4, is involved in the neuronal differentiation of NG2 cells. When TSP4 was overexpressed, NG2 cells underwent spontaneous neuronal differentiation, as demonstrated by the induction of various neuronal differentiation markers such as NeuN, Tuj1, and NF200, at the messenger RNA and protein levels. In contrast, TSP4 silencing had an opposite effect on the expression of neuronal differentiation markers in NG2 cells. Next, the signaling pathway responsible for TSP4-mediated NG2 cell differentiation was investigated. We found that ERK but not p38 and AKT signaling was affected by TSP4 overexpression. Furthermore, when ERK signaling was blocked by the inhibitor U0126, the neuronal marker expression of NG2 cells was substantially increased. Together, these findings suggested that TSP4 promoted neuronal differentiation of NG2 cells by inhibiting ERK/MAPK signaling, revealing a novel role of TSP4 in cell fate specification of NG2 cells.

  7. Close Vicinity of PrP Expressing Cells (FDC) with Noradrenergic Fibers in Healthy Sheep Spleen

    PubMed Central

    Lezmi, S.; Hunsmann, G.; Baron, T.

    2001-01-01

    In naturally and experimentally occurring scrapie in sheep, prions invade the immune system and replicate in lymphoid organs. Here we analysed immunohistochemically, in seven spleens of 6-month-old healthy sheep, the nature of the cells expressing prion protein (PrP) potentially supporting prion replication, as well as their relationship with autonomic innervation. PrP was identified using either RB1 rabbit antiserum or 4F2 monoclonal antibody directed against AA 108–123 portion of the bovine and AA 79–92 of human prion protein respectively. Using double labelling analysis, we demonstrated that PrPc is expressed by follicular dendritic cells using a specific monoclonal antibody (CNA42). We also showed the close vicinity of these PrP expressing cells with noradrenergic fibers, using a polyclonal tyrosine hydroxylase antibody. Our results may help the study of the cellular requirements for the possible neuroinvasion from the spleen. PMID:11785673

  8. Astrocyte NMDA receptors' activity sustains neuronal survival through a Cdk5–Nrf2 pathway

    PubMed Central

    Jimenez-Blasco, D; Santofimia-Castaño, P; Gonzalez, A; Almeida, A; Bolaños, J P

    2015-01-01

    Neurotransmission unavoidably increases mitochondrial reactive oxygen species. However, the intrinsic antioxidant defense of neurons is weak and hence the mechanism whereby these cells are physiologically protected against oxidative damage is unknown. Here we found that the antioxidant defense of neurons is repressed owing to the continuous protein destabilization of the master antioxidant transcriptional activator, nuclear factor-erythroid 2-related factor-2 (Nrf2). By contrast, Nrf2 is highly stable in neighbor astrocytes explaining their robust antioxidant defense and resistance against oxidative stress. We also show that subtle and persistent stimulation of N-methyl-d-aspartate receptors (NMDAR) in astrocytes, through a mechanism not requiring extracellular Ca2+ influx, upregulates a signal transduction pathway involving phospholipase C-mediated endoplasmic reticulum release of Ca2+ and protein kinase Cδ activation. Active protein kinase Cδ promotes, by phosphorylation, the stabilization of p35, a cyclin-dependent kinase-5 (Cdk5) cofactor. Active p35/Cdk5 complex in the cytosol phosphorylates Nrf2 at Thr395, Ser433 and Thr439 that is sufficient to promote Nrf2 translocation to the nucleus and induce the expression of antioxidant genes. Furthermore, this Cdk5–Nrf2 transduction pathway boosts glutathione metabolism in astrocytes efficiently protecting closely spaced neurons against oxidative damage. Thus, intercellular communication through NMDAR couples neurotransmission with neuronal survival. PMID:25909891

  9. Anti-NGF monoclonal antibody muMab 911 does not deplete neurons in the superior cervical ganglia of young or old adult rats.

    PubMed

    Marcek, John; Okerberg, Carlin; Liu, Chang-Ning; Potter, David; Butler, Paul; Boucher, Magalie; Zorbas, Mark; Mouton, Peter; Nyengaard, Jens R; Somps, Chris

    2016-10-01

    Nerve growth factor (NGF) blocking therapies are an emerging and effective approach to pain management. However, concerns about the potential for adverse effects on the structure and function of the peripheral nervous system have slowed their development. Early studies using NGF antisera in adult rats reported effects on the size and number of neurons in the sympathetic chain ganglia. In the work described here, both young adult (6-8 week) and fully mature (7-8 month) rats were treated with muMab 911, a selective, murine, anti-NGF monoclonal antibody, to determine if systemic exposures to pharmacologically active levels of antibody for 1 month cause loss of neurons in the sympathetic superior cervical ganglia (SCG). State-of-the-art, unbiased stereology performed by two independent laboratories was used to determine the effects of muMab 911 on SCG neuronal number and size, as well as ganglion size. Following muMab 911 treatment, non-statistically significant trends toward smaller ganglia, and smaller and fewer neurons, were seen when routine, nonspecific stains were used in stereologic assessments. However, when noradrenergic neurons were identified using tyrosine hydroxylase (TH) immunoreactivity, trends toward fewer neurons observed with routine stains were not apparent. The only statistically significant effects detected were lower SCG weights in muMab 911-treated rats, and a smaller volume of TH immunoreactivity in neurons from younger rats treated with muMab 911. These results indicate that therapeutically relevant exposures to the anti-NGF monoclonal antibody muMab 911 for 1 month have no effect on neuron numbers within the SCG from young or old adult rats. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Transglutaminase 2: Friend or foe? The discordant role in neurons and astrocytes.

    PubMed

    Quinn, Breandan R; Yunes-Medina, Laura; Johnson, Gail V W

    2018-03-23

    Members of the transglutaminase family catalyze the formation of isopeptide bonds between a polypeptide-bound glutamine and a low molecular weight amine (e.g., spermidine) or the ɛ-amino group of a polypeptide-bound lysine. Transglutaminase 2 (TG2), a prominent member of this family, is unique because in addition to being a transamidating enzyme, it exhibits numerous other activities. As a result, TG2 plays a role in many physiological processes, and its function is highly cell type specific and relies upon a number of factors, including conformation, cellular compartment location, and local concentrations of Ca 2+ and guanine nucleotides. TG2 is the most abundant transglutaminase in the central nervous system (CNS) and plays a pivotal role in the CNS injury response. How TG2 affects the cell in response to an insult is strikingly different in astrocytes and neurons. In neurons, TG2 supports survival. Overexpression of TG2 in primary neurons protects against oxygen and glucose deprivation (OGD)-induced cell death and in vivo results in a reduction in infarct volume subsequent to a stroke. Knockdown of TG2 in primary neurons results in a loss of viability. In contrast, deletion of TG2 from astrocytes results in increased survival following OGD and improved ability to protect neurons from injury. Here, a brief overview of TG2 is provided, followed by a discussion of the role of TG2 in transcriptional regulation, cellular dynamics, and cell death. The differing roles TG2 plays in neurons and astrocytes are highlighted and compared to how TG2 functions in other cell types. © 2018 Wiley Periodicals, Inc.

  11. The role of GluN2A and GluN2B NMDA receptor subunits in AgRP and POMC neurons on body weight and glucose homeostasis.

    PubMed

    Üner, Aykut; Gonçalves, Gabriel H M; Li, Wenjing; Porceban, Matheus; Caron, Nicole; Schönke, Milena; Delpire, Eric; Sakimura, Kenji; Bjørbæk, Christian

    2015-10-01

    Hypothalamic agouti-related peptide (AgRP) and pro-opiomelanocortin (POMC) expressing neurons play critical roles in control of energy balance. Glutamatergic input via n-methyl-d-aspartate receptors (NMDARs) is pivotal for regulation of neuronal activity and is required in AgRP neurons for normal body weight homeostasis. NMDARs typically consist of the obligatory GluN1 subunit and different GluN2 subunits, the latter exerting crucial differential effects on channel activity and neuronal function. Currently, the role of specific GluN2 subunits in AgRP and POMC neurons on whole body energy and glucose balance is unknown. We used the cre-lox system to genetically delete GluN2A or GluN2B only from AgRP or POMC neurons in mice. Mice were then subjected to metabolic analyses and assessment of AgRP and POMC neuronal function through morphological studies. We show that loss of GluN2B from AgRP neurons reduces body weight, fat mass, and food intake, whereas GluN2B in POMC neurons is not required for normal energy balance control. GluN2A subunits in either AgRP or POMC neurons are not required for regulation of body weight. Deletion of GluN2B reduces the number of AgRP neurons and decreases their dendritic length. In addition, loss of GluN2B in AgRP neurons of the morbidly obese and severely diabetic leptin-deficient Lep (ob/ob) mice does not affect body weight and food intake but, remarkably, leads to full correction of hyperglycemia. Lep (ob/ob) mice lacking GluN2B in AgRP neurons are also more sensitive to leptin's anti-obesity actions. GluN2B-containing NMDA receptors in AgRP neurons play a critical role in central control of body weight homeostasis and blood glucose balance via mechanisms that likely involve regulation of AgRP neuronal survival and structure, and modulation of hypothalamic leptin action.

  12. Are antidepressant drugs that combine serotonergic and noradrenergic mechanisms of action more effective than the selective serotonin reuptake inhibitors in treating major depressive disorder? A meta-analysis of studies of newer agents.

    PubMed

    Papakostas, George I; Thase, Michael E; Fava, Maurizio; Nelson, J Craig; Shelton, Richard C

    2007-12-01

    Recent studies suggest that the treatment of major depressive disorder (MDD) with newer antidepressant drugs that simultaneously enhance norepinephrine and serotonin neurotransmission might result in higher response and remission rates than the selective serotonin reuptake inhibitors (SSRIs). The goal of our work was to compare response rates among patients with MDD treated with either of these two broad categories of antidepressant drugs. Medline/Pubmed, EMBase, clinical trial registries, program syllabi from major psychiatric meetings held since 1995, and documents from relevant pharmaceutical companies were searched for double-blind, randomized trials comparing a newer serotonergic-noradrenergic antidepressant drug (venlafaxine, duloxetine, milnacipran, mirtazapine, mianserin, or moclobemide) with an SSRI for MDD. Ninety-three trials (n = 17,036) were combined using a random-effects model. Treatment with serotonergic + noradrenergic antidepressant drugs was more likely to result in clinical response than the SSRIs (risk ratio [RR] = 1.059; response rates 63.6% versus 59.3%; p = .003). There was no evidence for heterogeneity among studies combined (p = 1.0). Excluding each individual agent did not significantly alter the pooled RR. With the exception of duloxetine (.985), RRs for response for each individual serotonergic + noradrenergic antidepressant drug were within the 95% confidence interval of the pooled RR (1.019-1.101). Serotonergic-noradrenergic antidepressant drugs seem to have a modest efficacy advantage compared with SSRIs in MDD. With the Number Needed to Treat (NNT) statistic as one indicator of clinical significance, nearly 24 patients would need to be treated with dual-action antidepressant drugs instead of SSRIs in order to obtain one additional responder. This difference falls well below the mark of NNT = 10 suggested by the United Kingdom's National Institute of Clinical Excellence but nonetheless might be of public health relevance given the

  13. Protection of neurons from high glucose-induced injury by deletion of MAD2B

    PubMed Central

    Meng, Xianfang; Wang, Xiaolan; Tian, Xiujuan; Yang, Zhihua; Li, Man; Zhang, Chun

    2014-01-01

    Diabetic encephalopathy may lead to cognitive deficits in diabetic patients and diminish quality of life. It has been shown that protracted hyperglycaemia is directly associated with neuronal apoptosis, which is involved in diabetic encephalopathy. The anaphase-promoting complex (APC) is essential for the survival of post-mitotic neurons. In our previous study, we found that the mitotic arrest deficient protein MAD2B, one of APC inhibitors, was expressed in neurons in central nervous system. However, whether MAD2B is involved in hyperglycaemia-induced apoptosis and thus takes part in diabetic encephalopathy is still unknown. To address this issue, we first explored the expression of MAD2B and cyclin B1 detected by immunofluorescence and Western blot. It was found that hyperglycaemia remarkably increased the expression of MAD2B and accumulation of cyclin B1 in cortices of diabetes mellitus rat model and in cultured primary neurons. To further explore the role of MAD2B in hyperglycaemia-induced neuronal injury, we depleted MAD2B expression by a specifically targeted shRNA against MAD2B. We observed that MAD2B deficiency alleviated cyclin B1 expression and apoptotic neuronal death. These results demonstrate that MAD2B expression is the main culprit for accumulation of cyclin B1 and apoptosis in neurons under high glucose. Moreover, inhibition of the expression of MAD2B prevented neurons from entering an aberrant S phase that led differentiated neurons into apoptotic cell death. These results suggest that hyperglycaemia induced neuronal apoptosis through inducing expression of MAD2B, which represents a novel mechanism of diabetic encephalopathy. PMID:24444371

  14. Ctip2-, Satb2-, Prox1-, and GAD65-Expressing Neurons in Rat Cultures: Preponderance of Single- and Double-Positive Cells, and Cell Type-Specific Expression of Neuron-Specific Gene Family Members, Nsg-1 (NEEP21) and Nsg-2 (P19).

    PubMed

    Digilio, Laura; Yap, Chan Choo; Winckler, Bettina

    2015-01-01

    The brain consists of many distinct neuronal cell types, but which cell types are present in widely used primary cultures of embryonic rodent brain is often not known. We characterized how abundantly four cell type markers (Ctip2, Satb2, Prox1, GAD65) were represented in cultured rat neurons, how easily neurons expressing different markers can be transfected with commonly used plasmids, and whether neuronal-enriched endosomal proteins Nsg-1 (NEEP21) and Nsg-2 (P19) are ubiquitously expressed in all types of cultured neurons. We found that cultured neurons stably maintain cell type identities that are reflective of cell types in vivo. This includes neurons maintaining simultaneous expression of two transcription factors, such as Ctip2+/Satb2+ or Prox1+/Ctip2+ double-positive cells, which have also been described in vivo. Secondly, we established the superior efficiency of CAG promoters for both Lipofectamine-mediated transfection as well as for electroporation. Thirdly, we discovered that Nsg-1 and Nsg-2 were not expressed equally in all neurons: whereas high levels of both Nsg-1 and Nsg-2 were found in Satb2-, Ctip2-, and GAD65-positive neurons, Prox1-positive neurons in hippocampal cultures expressed low levels of both. Our findings thus highlight the importance of identifying neuronal cell types for doing cell biology in cultured neurons: Keeping track of neuronal cell type might uncover effects in assays that might otherwise be masked by the mixture of responsive and non-responsive neurons in the dish.

  15. Serotonin 2C receptors in pro-opiomelanocortin neurons regulate energy and glucose homeostasis.

    PubMed

    Berglund, Eric D; Liu, Chen; Sohn, Jong-Woo; Liu, Tiemin; Kim, Mi Hwa; Lee, Charlotte E; Vianna, Claudia R; Williams, Kevin W; Xu, Yong; Elmquist, Joel K

    2013-12-01

    Energy and glucose homeostasis are regulated by central serotonin 2C receptors. These receptors are attractive pharmacological targets for the treatment of obesity; however, the identity of the serotonin 2C receptor-expressing neurons that mediate the effects of serotonin and serotonin 2C receptor agonists on energy and glucose homeostasis are unknown. Here, we show that mice lacking serotonin 2C receptors (Htr2c) specifically in pro-opiomelanocortin (POMC) neurons had normal body weight but developed glucoregulatory defects including hyperinsulinemia, hyperglucagonemia, hyperglycemia, and insulin resistance. Moreover, these mice did not show anorectic responses to serotonergic agents that suppress appetite and developed hyperphagia and obesity when they were fed a high-fat/high-sugar diet. A requirement of serotonin 2C receptors in POMC neurons for the maintenance of normal energy and glucose homeostasis was further demonstrated when Htr2c loss was induced in POMC neurons in adult mice using a tamoxifen-inducible POMC-cre system. These data demonstrate that serotonin 2C receptor-expressing POMC neurons are required to control energy and glucose homeostasis and implicate POMC neurons as the target for the effect of serotonin 2C receptor agonists on weight-loss induction and improved glycemic control.

  16. Period 2 gene deletion abolishes β-endorphin neuronal response to ethanol

    PubMed Central

    Agapito, Maria; Mian, Nadia; Boyadjieva, Nadka I.; Sarkar, Dipak K.

    2010-01-01

    Background Ethanol exposure during early life has been shown to permanently alter the circadian expression of clock regulatory genes and the β-endorphin precursor proopiomelanocortin (POMC) gene in the hypothalamus. Ethanol also alters the stress- and immune-regulatory functions of β-endorphin neurons in laboratory rodents. Our aim was to determine whether the circadian clock regulatory Per2 gene modulates the action of ethanol on β-endorphin neurons in mice. Methods Per2 mutant (mPer2Brdml) and wild type (C57BL/6J) mice were used to determine the effect of Per2 mutation on ethanol-regulated β-endorphin neuronal activity during neonatal period using an in vitro mediobasal hypothalamic (MBH) cell culture model and an in vivo milk formula feeding animal model. The β-endorphin neuronal activity following acute and chronic ethanol treatments, was evaluated by measuring the peptide released from cultured cells or peptide levels in the MBH tissues, using enzyme-linked immunosorbent assay (ELISA). Results Per2 mutant mice showed a higher basal level of β-endorphin release from cultured MBH cells and a moderate increase in the peptide content in the MBH in comparison to control mice. However, unlike wild type mice, Per2 mutant mice showed no stimulatory or inhibitory β-endorphin secretory responses to acute and chronic ethanol challenges in vitro. Furthermore, Per2 mutant mice, but not wild type mice, failed to show the stimulatory and inhibitory responses of MBH β-endorphin levels to acute and chronic ethanol challenges in vivo. Conclusions These results suggest for the first time that the Per2 gene may be critically involved in regulating β-endorphin neuronal function. Furthermore, the data revealed an involvement of the Per2 gene in regulating β-endorphin neuronal responses to ethanol. PMID:20586752

  17. Reduced synaptic density and deficient locomotor response in neuronal activity-regulated pentraxin 2a mutant zebrafish.

    PubMed

    Elbaz, Idan; Lerer-Goldshtein, Tali; Okamoto, Hitoshi; Appelbaum, Lior

    2015-04-01

    Neuronal-activity-regulated pentraxin (NARP/NPTX2/NP2) is a secreted synaptic protein that regulates the trafficking of glutamate receptors and mediates learning, memory, and drug addiction. The role of NPTX2 in regulating structural synaptic plasticity and behavior in a developing vertebrate is indefinite. We characterized the expression of nptx2a in larvae and adult zebrafish and established a transcription activator-like effector nuclease (TALEN)-mediated nptx2a mutant (nptx2a(-/-)) to study the role of Nptx2a in regulating structural synaptic plasticity and behavior. Similar to mammals, the zebrafish nptx2a was expressed in excitatory neurons in the brain and spinal cord. Its expression was induced in response to a mechanosensory stimulus but did not change during day and night. Behavioral assays showed that loss of Nptx2a results in reduced locomotor response to light-to-dark transition states and to a sound stimulus. Live imaging of synapses using the transgenic nptx2a:GAL4VP16 zebrafish and a fluorescent presynaptic synaptophysin (SYP) marker revealed reduced synaptic density in the axons of the spinal motor neurons and the anterodorsal lateral-line ganglion (gAD), which regulate locomotor activity and locomotor response to mechanosensory stimuli, respectively. These results suggest that Nptx2a affects locomotor response to external stimuli by mediating structural synaptic plasticity in excitatory neuronal circuits. © FASEB.

  18. Cadherin-2 Is Required Cell Autonomously for Collective Migration of Facial Branchiomotor Neurons.

    PubMed

    Rebman, Jane K; Kirchoff, Kathryn E; Walsh, Gregory S

    2016-01-01

    Collective migration depends on cell-cell interactions between neighbors that contribute to their overall directionality, yet the mechanisms that control the coordinated migration of neurons remains to be elucidated. During hindbrain development, facial branchiomotor neurons (FBMNs) undergo a stereotypic tangential caudal migration from their place of birth in rhombomere (r)4 to their final location in r6/7. FBMNs engage in collective cell migration that depends on neuron-to-neuron interactions to facilitate caudal directionality. Here, we demonstrate that Cadherin-2-mediated neuron-to-neuron adhesion is necessary for directional and collective migration of FBMNs. We generated stable transgenic zebrafish expressing dominant-negative Cadherin-2 (Cdh2ΔEC) driven by the islet1 promoter. Cell-autonomous inactivation of Cadherin-2 function led to non-directional migration of FBMNs and a defect in caudal tangential migration. Additionally, mosaic analysis revealed that Cdh2ΔEC-expressing FBMNs are not influenced to migrate caudally by neighboring wild-type FBMNs due to a defect in collective cell migration. Taken together, our data suggest that Cadherin-2 plays an essential cell-autonomous role in mediating the collective migration of FBMNs.

  19. TASK-2 Channels Contribute to pH Sensitivity of Retrotrapezoid Nucleus Chemoreceptor Neurons

    PubMed Central

    Wang, Sheng; Benamer, Najate; Zanella, Sébastien; Kumar, Natasha N.; Shi, Yingtang; Bévengut, Michelle; Penton, David; Guyenet, Patrice G.; Lesage, Florian

    2013-01-01

    Phox2b-expressing glutamatergic neurons of the retrotrapezoid nucleus (RTN) display properties expected of central respiratory chemoreceptors; they are directly activated by CO2/H+ via an unidentified pH-sensitive background K+ channel and, in turn, facilitate brainstem networks that control breathing. Here, we used a knock-out mouse model to examine whether TASK-2 (K2P5), an alkaline-activated background K+ channel, contributes to RTN neuronal pH sensitivity. We made patch-clamp recordings in brainstem slices from RTN neurons that were identified by expression of GFP (directed by the Phox2b promoter) or β-galactosidase (from the gene trap used for TASK-2 knock-out). Whereas nearly all RTN cells from control mice were pH sensitive (95%, n = 58 of 61), only 56% of GFP-expressing RTN neurons from TASK-2−/− mice (n = 49 of 88) could be classified as pH sensitive (>30% reduction in firing rate from pH 7.0 to pH 7.8); the remaining cells were pH insensitive (44%). Moreover, none of the recorded RTN neurons from TASK-2−/− mice selected based on β-galactosidase activity (a subpopulation of GFP-expressing neurons) were pH sensitive. The alkaline-activated background K+ currents were reduced in amplitude in RTN neurons from TASK-2−/− mice that retained some pH sensitivity but were absent from pH-insensitive cells. Finally, using a working heart–brainstem preparation, we found diminished inhibition of phrenic burst amplitude by alkalization in TASK-2−/− mice, with apneic threshold shifted to higher pH levels. In conclusion, alkaline-activated TASK-2 channels contribute to pH sensitivity in RTN neurons, with effects on respiration in situ that are particularly prominent near apneic threshold. PMID:24107938

  20. The influence of botulinum toxin type A (BTX) on the immunohistochemical characteristics of noradrenergic and cholinergic nerve fibers supplying the porcine urinary bladder wall.

    PubMed

    Lepiarczyk, E; Bossowska, A; Kaleczyc, J; Majewski, M

    2011-01-01

    Botulinum toxin (BTX) belongs to a family of neurotoxins which strongly influence the function of autonomic neurons supplying the urinary bladder. Accordingly, BTX has been used as an effective drug in experimental therapies of a range of neurogenic bladder disorders. However, there is no detailed information dealing with the influence of BTX on the morphological and chemical properties of nerve fibres supplying the urinary bladder wall. Therefore, the present study investigated, using double-labeling immunohistochemistry, the distribution, relative frequency and chemical coding of cholinergic and noradrenergic nerve fibers supplying the wall of the urinary bladder in normal female pigs (n = 6) and in the pigs (n = 6) after intravesical BTX injections. In the pigs injected with BTX, the number of adrenergic (DbetaH-positive) nerve fibers distributed in the bladder wall (urothelium, submucosa and muscle coat) was distinctly higher while the number of cholinergic (VAChT-positive) nerve terminals was lower than that found in the control animals. Moreover, the injections of BTX resulted in some changes dealing with the chemical coding of the adrenergic nerve fibers. In contrast to the normal pigs, in BTX injected animals the number of DbetaH/NPY- or DbetaH/CGRP-positive axons was higher in the muscle coat, and some fibres distributed in the urothelium and submucosa expressed immunoreactivity to CGRP. The results obtained suggest that the therapeutic effects of BTX on the urinary bladder might be dependent on changes in the distribution and chemical coding of nerve fibers supplying this organ.

  1. Dlx1/2 and Otp coordinate the production of hypothalamic GHRH- and AgRP-neurons.

    PubMed

    Lee, Bora; Kim, Janghyun; An, Taekyeong; Kim, Sangsoo; Patel, Esha M; Raber, Jacob; Lee, Soo-Kyung; Lee, Seunghee; Lee, Jae W

    2018-05-23

    Despite critical roles of the hypothalamic arcuate neurons in controlling the growth and energy homeostasis, the gene regulatory network directing their development remains unclear. Here we report that the transcription factors Dlx1/2 and Otp coordinate the balanced generation of the two functionally related neurons in the hypothalamic arcuate nucleus, GHRH-neurons promoting the growth and AgRP-neurons controlling the feeding and energy expenditure. Dlx1/2-deficient mice show a loss-of-GHRH-neurons and an increase of AgRP-neurons, and consistently develop dwarfism and consume less energy. These results indicate that Dlx1/2 are crucial for specifying the GHRH-neuronal identity and, simultaneously, for suppressing AgRP-neuronal fate. We further show that Otp is required for the generation of AgRP-neurons and that Dlx1/2 repress the expression of Otp by directly binding the Otp gene. Together, our study demonstrates that the identity of GHRH- and AgRP-neurons is synchronously specified and segregated by the Dlx1/2-Otp gene regulatory axis.

  2. Excitotoxicity-induced prostaglandin D2 production induces sustained microglial activation and delayed neuronal death.

    PubMed

    Iwasa, Kensuke; Yamamoto, Shinji; Yagishita, Sosuke; Maruyama, Kei; Yoshikawa, Keisuke

    2017-04-01

    Excitotoxicity is the pivotal mechanism of neuronal death. Prostaglandins (PGs) produced during excitotoxicity play important roles in neurodegenerative conditions. Previously, we demonstrated that initial burst productions of PGD 2 , PGE 2 , and PGF 2α are produced by cyclooxygenase-2 (COX-2) in the hippocampus following a single systemic kainic acid (KA) administration. In addition, we showed that blocking of all PG productions ameliorated hippocampal delayed neuronal death at 30 days after KA administration. To investigate the role of individual PGs in the delayed neuronal death, we performed intracerebroventricular injection of PGD 2 , PGE 2 , or PGF 2α in rats whose hippocampal PG productions were entirely blocked by pretreatment of NS398, a COX-2 selective inhibitor. Administration of PGD 2 and PGF 2α had a latent contribution to the delayed neuronal death, sustained over 30 days after a single KA treatment. Furthermore, PGD 2 enhanced microglial activation, which may be involved in the delayed neuronal death in the hippocampus. These findings suggest that excitotoxic delayed neuronal death is mediated through microglia activated by PGD 2 . Copyright © 2017 by the American Society for Biochemistry and Molecular Biology, Inc.

  3. Lhx2 Expression in Postmitotic Cortical Neurons Initiates Assembly of the Thalamocortical Somatosensory Circuit.

    PubMed

    Wang, Chia-Fang; Hsing, Hsiang-Wei; Zhuang, Zi-Hui; Wen, Meng-Hsuan; Chang, Wei-Jen; Briz, Carlos G; Nieto, Marta; Shyu, Bai Chuang; Chou, Shen-Ju

    2017-01-24

    Cortical neurons must be specified and make the correct connections during development. Here, we examine a mechanism initiating neuronal circuit formation in the barrel cortex, a circuit comprising thalamocortical axons (TCAs) and layer 4 (L4) neurons. When Lhx2 is selectively deleted in postmitotic cortical neurons using conditional knockout (cKO) mice, L4 neurons in the barrel cortex are initially specified but fail to form cellular barrels or develop polarized dendrites. In Lhx2 cKO mice, TCAs from the thalamic ventral posterior nucleus reach the barrel cortex but fail to further arborize to form barrels. Several activity-regulated genes and genes involved in regulating barrel formation are downregulated in the Lhx2 cKO somatosensory cortex. Among them, Btbd3, an activity-regulated gene controlling dendritic development, is a direct downstream target of Lhx2. We find that Lhx2 confers neuronal competency for activity-dependent dendritic development in L4 neurons by inducing the expression of Btbd3. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

  4. Loss of thymidine kinase 2 alters neuronal bioenergetics and leads to neurodegeneration

    PubMed Central

    Bartesaghi, Stefano; Betts-Henderson, Joanne; Cain, Kelvin; Dinsdale, David; Zhou, Xiaoshan; Karlsson, Anna; Salomoni, Paolo; Nicotera, Pierluigi

    2010-01-01

    Mutations of thymidine kinase 2 (TK2), an essential component of the mitochondrial nucleotide salvage pathway, can give rise to mitochondrial DNA (mtDNA) depletion syndromes (MDS). These clinically heterogeneous disorders are characterized by severe reduction in mtDNA copy number in affected tissues and are associated with progressive myopathy, hepatopathy and/or encephalopathy, depending in part on the underlying nuclear genetic defect. Mutations of TK2 have previously been associated with an isolated myopathic form of MDS (OMIM 609560). However, more recently, neurological phenotypes have been demonstrated in patients carrying TK2 mutations, thus suggesting that loss of TK2 results in neuronal dysfunction. Here, we directly address the role of TK2 in neuronal homeostasis using a knockout mouse model. We demonstrate that in vivo loss of TK2 activity leads to a severe ataxic phenotype, accompanied by reduced mtDNA copy number and decreased steady-state levels of electron transport chain proteins in the brain. In TK2-deficient cerebellar neurons, these abnormalities are associated with impaired mitochondrial bioenergetic function, aberrant mitochondrial ultrastructure and degeneration of selected neuronal types. Overall, our findings demonstrate that TK2 deficiency leads to neuronal dysfunction in vivo, and have important implications for understanding the mechanisms of neurological impairment in MDS. PMID:20123860

  5. Loss of thymidine kinase 2 alters neuronal bioenergetics and leads to neurodegeneration.

    PubMed

    Bartesaghi, Stefano; Betts-Henderson, Joanne; Cain, Kelvin; Dinsdale, David; Zhou, Xiaoshan; Karlsson, Anna; Salomoni, Paolo; Nicotera, Pierluigi

    2010-05-01

    Mutations of thymidine kinase 2 (TK2), an essential component of the mitochondrial nucleotide salvage pathway, can give rise to mitochondrial DNA (mtDNA) depletion syndromes (MDS). These clinically heterogeneous disorders are characterized by severe reduction in mtDNA copy number in affected tissues and are associated with progressive myopathy, hepatopathy and/or encephalopathy, depending in part on the underlying nuclear genetic defect. Mutations of TK2 have previously been associated with an isolated myopathic form of MDS (OMIM 609560). However, more recently, neurological phenotypes have been demonstrated in patients carrying TK2 mutations, thus suggesting that loss of TK2 results in neuronal dysfunction. Here, we directly address the role of TK2 in neuronal homeostasis using a knockout mouse model. We demonstrate that in vivo loss of TK2 activity leads to a severe ataxic phenotype, accompanied by reduced mtDNA copy number and decreased steady-state levels of electron transport chain proteins in the brain. In TK2-deficient cerebellar neurons, these abnormalities are associated with impaired mitochondrial bioenergetic function, aberrant mitochondrial ultrastructure and degeneration of selected neuronal types. Overall, our findings demonstrate that TK2 deficiency leads to neuronal dysfunction in vivo, and have important implications for understanding the mechanisms of neurological impairment in MDS.

  6. Extracellular Ca2+ Acts as a Mediator of Communication from Neurons to Glia

    PubMed Central

    Torres, Arnulfo; Wang, Fushun; Xu, Qiwu; Fujita, Takumi; Dobrowolski, Radoslaw; Willecke, Klaus; Takano, Takahiro; Nedergaard, Maiken

    2013-01-01

    Defining the pathways through which neurons and astrocytes communicate may contribute to the elucidation of higher central nervous system functions. We investigated the possibility that decreases in extracellular calcium ion concentration ([Ca2+]e) that occur during synaptic transmission might mediate signaling from neurons to glia. Using noninvasive photolysis of the photolabile Ca2+ buffer diazo-2 {N-[2-[2-[2-[bis(carboxymethyl)amino]-5-(diazoacetyl)phenoxy]ethoxy]-4-methylphenyl]-N-(carboxymethyl)-, tetrapotassium salt} to reduce [Ca2+]e or caged glutamate to simulate glutamatergic transmission, we found that a local decline in extracellular Ca2+ triggered astrocytic adenosine triphosphate (ATP) release and astrocytic Ca2+ signaling. In turn, activation of purinergic P2Y1 receptors on a subset of inhibitory interneurons initiated the generation of action potentials by these interneurons, thereby enhancing synaptic inhibition. Thus, astrocytic ATP release evoked by an activity-associated decrease in [Ca2+]e may provide a negative feedback mechanism that potentiates inhibitory transmission in response to local hyperexcitability. PMID:22275221

  7. The Role of Ca2+ and BK Channels of Locus Coeruleus (LC) Neurons as a Brake to the CO2 Chemosensitivity Response of Rats.

    PubMed

    Imber, Ann N; Patrone, Luis G A; Li, Ke-Yong; Gargaglioni, Luciane H; Putnam, Robert W

    2018-06-15

    The cellular mechanisms by which LC neurons respond to hypercapnia are usually attributed to an "accelerator" whereby hypercapnic acidosis causes an inhibition of K + channels or activation of Na + and Ca +2 channels to depolarize CO 2 -sensitive neurons. Nevertheless, it is still unknown if this "accelerator" mechanism could be controlled by a brake phenomenon. Whole-cell patch clamping, fluorescence imaging microscopy and plethysmography were used to study the chemosensitive response of the LC neurons. Hypercapnic acidosis activates L-type Ca 2+ channels and large conductance Ca-activated K + (BK) channels, which function as a "brake" on the chemosensitive response of LC neurons. Our findings indicate that both Ca 2+ and BK currents develop over the first 2 weeks of postnatal life in rat LC slices and that this brake pathway may cause the developmental decrease in the chemosensitive firing rate response of LC neurons to hypercapnic acidosis. Inhibition of this brake by paxilline (BK channel inhibitor) returns the magnitude of the chemosensitive firing rate response from LC neurons in rats older than P10 to high values similar to those in LC neurons from younger rats. Inhibition of BK channels in LC neurons by bilateral injections of paxilline into the LC results in a significant increase in the hypercapnic ventilatory response of adult rats. Our findings indicate that a BK channel-based braking system helps to determine the chemosensitive respiratory drive of LC neurons and contributes to the hypercapnic ventilatory response. Perhaps, abnormalities of this braking system could result in hypercapnia-induced respiratory disorders and panic responses. Copyright © 2018 IBRO. Published by Elsevier Ltd. All rights reserved.

  8. Slitrk1-deficient mice display elevated anxiety-like behavior and noradrenergic abnormalities.

    PubMed

    Katayama, K; Yamada, K; Ornthanalai, V G; Inoue, T; Ota, M; Murphy, N P; Aruga, J

    2010-02-01

    Mutations in SLITRK1 are found in patients with Tourette's syndrome and trichotillomania. SLITRK1 encodes a transmembrane protein containing leucine-rich repeats that is produced predominantly in the nervous system. However, the role of this protein is largely unknown, except that it can modulate neurite outgrowth in vitro. To clarify the role of Slitrk1 in vivo, we developed Slitrk1-knockout mice and analyzed their behavioral and neurochemical phenotypes. Slitrk1-deficient mice exhibited elevated anxiety-like behavior in the elevated plus-maze test as well as increased immobility time in forced swimming and tail suspension tests. Neurochemical analysis revealed that Slitrk1-knockout mice had increased levels of norepinephrine and its metabolite 3-methoxy-4-hydroxyphenylglycol. Administration of clonidine, an alpha2-adrenergic agonist that is frequently used to treat patients with Tourette's syndrome, attenuated the anxiety-like behavior of Slitrk1-deficient mice in the elevated plus-maze test. These results lead us to conclude that noradrenergic mechanisms are involved in the behavioral abnormalities of Slitrk1-deficient mice. Elevated anxiety due to Slitrk1 dysfunction may contribute to the pathogenesis of neuropsychiatric diseases such as Tourette's syndrome and trichotillomania.

  9. Neuronal Responses in Visual Area V2 (V2) of Macaque Monkeys with Strabismic Amblyopia

    PubMed Central

    Bi, H.; Zhang, B.; Tao, X.; Harwerth, R. S.; Smith, E. L.

    2011-01-01

    Amblyopia, a developmental disorder of spatial vision, is thought to result from a cascade of cortical deficits over several processing stages beginning at the primary visual cortex (V1). However, beyond V1, little is known about how cortical development limits the visual performance of amblyopic primates. We quantitatively analyzed the monocular and binocular responses of V1 and V2 neurons in a group of strabismic monkeys exhibiting varying depths of amblyopia. Unlike in V1, the relative effectiveness of the affected eye to drive V2 neurons was drastically reduced in the amblyopic monkeys. The spatial resolution and the orientation bias of V2, but not V1, neurons were subnormal for the affected eyes. Binocular suppression was robust in both cortical areas, and the magnitude of suppression in individual monkeys was correlated with the depth of their amblyopia. These results suggest that the reduced functional connections beyond V1 and the subnormal spatial filter properties of V2 neurons might have substantially limited the sensitivity of the amblyopic eyes and that interocular suppression was likely to have played a key role in the observed alterations of V2 responses and the emergence of amblyopia. PMID:21263036

  10. Neuronal responses in visual area V2 (V2) of macaque monkeys with strabismic amblyopia.

    PubMed

    Bi, H; Zhang, B; Tao, X; Harwerth, R S; Smith, E L; Chino, Y M

    2011-09-01

    Amblyopia, a developmental disorder of spatial vision, is thought to result from a cascade of cortical deficits over several processing stages beginning at the primary visual cortex (V1). However, beyond V1, little is known about how cortical development limits the visual performance of amblyopic primates. We quantitatively analyzed the monocular and binocular responses of V1 and V2 neurons in a group of strabismic monkeys exhibiting varying depths of amblyopia. Unlike in V1, the relative effectiveness of the affected eye to drive V2 neurons was drastically reduced in the amblyopic monkeys. The spatial resolution and the orientation bias of V2, but not V1, neurons were subnormal for the affected eyes. Binocular suppression was robust in both cortical areas, and the magnitude of suppression in individual monkeys was correlated with the depth of their amblyopia. These results suggest that the reduced functional connections beyond V1 and the subnormal spatial filter properties of V2 neurons might have substantially limited the sensitivity of the amblyopic eyes and that interocular suppression was likely to have played a key role in the observed alterations of V2 responses and the emergence of amblyopia.

  11. Effects of locus coeruleus stimulation on the responses of SI neurons of the rat to controlled natural and electrical stimulation of the skin.

    PubMed

    Snow, P J; Andre, P; Pompeiano, O

    1999-02-01

    1. The effects of microstimulation of the locus coeruleus (LC) region on the spontaneous discharge and the response of SI neurons to natural and electrical stimulation of the skin have been investigated in 26 urethane anesthetized Sprague-Dawley rats. In particular, one or two air puffs, 5-10 msec in duration, 1-2 psi, usually separated by an interval of 40 msec, were applied on the hairy skin of the wrist or the forepaw at the presentation rate of 1/sec. For units unresponsive to air puffs, similar presentation of low intensity electrical stimuli (0.2-5.0 V, 0.2-0.4 msec pulses) were applied through two needles inserted on the most effective area of the skin. Both natural and electrical stimulations of the skin were applied under control conditions, as well as 50 msec after a 250 msec train of 0.3 msec pulses at 40 Hz. 20-30 microA applied stereotaxically to the LC complex through a tungsten microelectrode. 2. Not all cortical units exhibited spontaneous discharge. Most of the units, however, which were spontaneously active, were inhibited by electrical stimulation of the LC complex, while the remaining ones were excited. The sites of stimulation, which included either the LC proper or the locus subcoeruleus, were identified following both anatomical and physiological criteria. 3. SI neurons recorded at sites between 400 and 950 microns below the surface of the cortex, thus being most likely granule cells of layers III and IV, responded to cutaneous stimuli with spikes which occurred with a latency of 20-30 msec in response to single air puffs and a latency of 15-20 msec in response to single electrical pulses to the skin. In both instances the response to the second stimulus applied at the interstimulus interval of 40 msec was markedly reduced or abolished due to postexcitatory inhibition following the response to the first stimulus (in-field inhibition). In contrast, units particularly located at or below 1000 microns from the cortical surface, which were of

  12. A Codimension-2 Bifurcation Controlling Endogenous Bursting Activity and Pulse-Triggered Responses of a Neuron Model

    PubMed Central

    Barnett, William H.; Cymbalyuk, Gennady S.

    2014-01-01

    The dynamics of individual neurons are crucial for producing functional activity in neuronal networks. An open question is how temporal characteristics can be controlled in bursting activity and in transient neuronal responses to synaptic input. Bifurcation theory provides a framework to discover generic mechanisms addressing this question. We present a family of mechanisms organized around a global codimension-2 bifurcation. The cornerstone bifurcation is located at the intersection of the border between bursting and spiking and the border between bursting and silence. These borders correspond to the blue sky catastrophe bifurcation and the saddle-node bifurcation on an invariant circle (SNIC) curves, respectively. The cornerstone bifurcation satisfies the conditions for both the blue sky catastrophe and SNIC. The burst duration and interburst interval increase as the inverse of the square root of the difference between the corresponding bifurcation parameter and its bifurcation value. For a given set of burst duration and interburst interval, one can find the parameter values supporting these temporal characteristics. The cornerstone bifurcation also determines the responses of silent and spiking neurons. In a silent neuron with parameters close to the SNIC, a pulse of current triggers a single burst. In a spiking neuron with parameters close to the blue sky catastrophe, a pulse of current temporarily silences the neuron. These responses are stereotypical: the durations of the transient intervals–the duration of the burst and the duration of latency to spiking–are governed by the inverse-square-root laws. The mechanisms described here could be used to coordinate neuromuscular control in central pattern generators. As proof of principle, we construct small networks that control metachronal-wave motor pattern exhibited in locomotion. This pattern is determined by the phase relations of bursting neurons in a simple central pattern generator modeled by a chain of

  13. Serotonin 2C receptor activates a distinct population of arcuate pro-opiomelanocortin neurons via TRPC channels

    USDA-ARS?s Scientific Manuscript database

    Serotonin 2C receptors (5-HT2CRs) expressed by pro-opiomelanocortin (POMC) neurons of hypothalamic arcuate nucleus regulate food intake, energy homeostasis ,and glucose metabolism. However, the cellular mechanisms underlying the effects of 5-HT to regulate POMC neuronal activity via 5-HT2CRs have no...

  14. LHX2 Interacts with the NuRD Complex and Regulates Cortical Neuron Subtype Determinants Fezf2 and Sox11.

    PubMed

    Muralidharan, Bhavana; Khatri, Zeba; Maheshwari, Upasana; Gupta, Ritika; Roy, Basabdatta; Pradhan, Saurabh J; Karmodiya, Krishanpal; Padmanabhan, Hari; Shetty, Ashwin S; Balaji, Chinthapalli; Kolthur-Seetharam, Ullas; Macklis, Jeffrey D; Galande, Sanjeev; Tole, Shubha

    2017-01-04

    In the developing cerebral cortex, sequential transcriptional programs take neuroepithelial cells from proliferating progenitors to differentiated neurons with unique molecular identities. The regulatory changes that occur in the chromatin of the progenitors are not well understood. During deep layer neurogenesis, we show that transcription factor LHX2 binds to distal regulatory elements of Fezf2 and Sox11, critical determinants of neuron subtype identity in the mouse neocortex. We demonstrate that LHX2 binds to the nucleosome remodeling and histone deacetylase histone remodeling complex subunits LSD1, HDAC2, and RBBP4, which are proximal regulators of the epigenetic state of chromatin. When LHX2 is absent, active histone marks at the Fezf2 and Sox11 loci are increased. Loss of LHX2 produces an increase, and overexpression of LHX2 causes a decrease, in layer 5 Fezf2 and CTIP2-expressing neurons. Our results provide mechanistic insight into how LHX2 acts as a necessary and sufficient regulator of genes that control cortical neuronal subtype identity. The functional complexity of the cerebral cortex arises from an array of distinct neuronal subtypes with unique connectivity patterns that are produced from common progenitors. This study reveals that transcription factor LHX2 regulates the numbers of specific cortical output neuron subtypes by controlling the genes that are required to produce them. Loss or increase in LHX2 during neurogenesis is sufficient to increase or decrease, respectively, a particular subcerebrally projecting population. Mechanistically, LHX2 interacts with chromatin modifying protein complexes to edit the chromatin landscape of its targets Fezf2 and Sox11, which regulates their expression and consequently the identities of the neurons produced. Thus, LHX2 is a key component of the control network for producing neurons that will participate in cortical circuitry. Copyright © 2017 Muralidharan et al.

  15. Regulation of TRPV2 by axotomy in sympathetic, but not sensory neurons.

    PubMed

    Gaudet, Andrew D; Williams, Sarah J; Hwi, Lucy P-R; Ramer, Matt S

    2004-08-13

    Neuropathic pain results from traumatic or disease-related insults to the nervous system. Mechanisms that have been postulated to underlie peripheral neuropathy commonly implicate afferent neurons that have been damaged but still project centrally to the spinal cord, and/or intact neurons that interact with degenerating distal portions of the injured neurons. One pain state that is observed following peripheral nerve injury in the rat is thermal hyperalgesia. The noxious heat-gated ion channel TRPV1 may be responsible for this increased sensitivity, as it is up-regulated in L4 dorsal root ganglion (DRG) neurons following L5 spinal nerve lesion (SpNL). The TRPV1 homologue TRPV2 (or VRL-1) is another member of the TRPV subfamily of TRP ion channels. TRPV2 is a nonselective cation channel activated by high noxious temperatures (>52 degrees C) and is present in a subset of medium- to large-diameter DRG neurons. To establish whether TRPV2 is endogenous to the spinal cord, we examined its expression in the dorsal horn following rhizotomy. We found no significant decrease in TRPV2 immunoreactivity, suggesting that TRPV2 is endogenous to the spinal cord. In order to determine whether TRPV2, like TRPV1, is regulated by peripheral axotomy, we performed L5 SpNL and characterized TRPV2 distribution in the DRG, spinal cord, brainstem, and sympathetic ganglia. Our results show that peripheral axotomy did not regulate TRPV2 in the DRG, spinal cord, or brainstem; however, TRPV2 was up-regulated in sympathetic postganglionic neurons following injury, suggesting a potential role for TRPV2 in sympathetically mediated neuropathic pain.

  16. Purα Repaired Expanded Hexanucleotide GGGGCC Repeat Noncoding RNA-Caused Neuronal Toxicity in Neuro-2a Cells.

    PubMed

    Shen, Jianying; Zhang, Yu; Zhao, Shi; Mao, Hong; Wang, Zhongjing; Li, Honglian; Xu, Zihui

    2018-05-01

    Expanded hexanucleotide GGGGCC repeat in a noncoding region of C9ORF72 is the most common cause of frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). However, its molecular pathogenesis remains unclear. In our previous study, the expanded GGGGCC repeats have been shown to be sufficient to cause neurodegeneration. In order to investigate the further role of expanded GGGGCC repeats in the neuron, the normal r(GGGGCC) 3 and mutant-type expanded r(GGGGCC) 30 expression vectors were transfected into Neuro-2a cells. Cell proliferation, dendrite development, and the proteins' levels of microtubule-associated protein-2 (MAP2) and cyclin-dependent kinase-5 (CDK5) were used to evaluate the cell toxicity of GGGGCC repeats on Neuro-2a cells. The results were shown that expression of expanded GGGGCC repeats caused neuronal cell toxicity in Neuro-2a cells, enhanced the expression of pMAP2 and pCDK5. Moreover, overexpression of Purα repaired expanded GGGGCC repeat-inducing neuronal toxicity in Neuro-2a cells and reduced the expression of pMAP2 and pCDK5. In all, our findings suggested that the expanded GGGGCC repeats might cause neurodegeneration through destroyed neuron cells. And the GGGGCC repeat-induced neuronal cell toxicity was inhibited by upregulation of Purα. We inferred that Purα inhibits expanded GGGGCC repeat-inducing neurodegeneration, which might reveal a novel mechanism of neurodegenerative diseases ALS and FTD.

  17. Protease-Activated Receptor 2 Activation Inhibits N-Type Ca2+ Currents in Rat Peripheral Sympathetic Neurons

    PubMed Central

    Kim, Young-Hwan; Ahn, Duck-Sun; Kim, Myeong Ok; Joeng, Ji-Hyun; Chung, Seungsoo

    2014-01-01

    The protease-activated receptor (PAR)-2 is highly expressed in endothelial cells and vascular smooth muscle cells. It plays a crucial role in regulating blood pressure via the modulation of peripheral vascular tone. Although several mechanisms have been suggested to explain PAR-2-induced hypotension, the precise mechanism remains to be elucidated. To investigate this possibility, we investigated the effects of PAR-2 activation on N-type Ca2+ currents (ICa-N) in isolated neurons of the celiac ganglion (CG), which is involved in the sympathetic regulation of mesenteric artery vascular tone. PAR-2 agonists irreversibly diminished voltage-gated Ca2+ currents (ICa), measured using the patch-clamp method, in rat CG neurons, whereas thrombin had little effect on ICa. This PAR-2-induced inhibition was almost completely prevented by ω-CgTx, a potent N-type Ca2+ channel blocker, suggesting the involvement of N-type Ca2+ channels in PAR-2-induced inhibition. In addition, PAR-2 agonists inhibited ICa–N in a voltage-independent manner in rat CG neurons. Moreover, PAR-2 agonists reduced action potential (AP) firing frequency as measured using the current-clamp method in rat CG neurons. This inhibition of AP firing induced by PAR-2 agonists was almost completely prevented by ω-CgTx, indicating that PAR-2 activation may regulate the membrane excitability of peripheral sympathetic neurons through modulation of N-type Ca2+ channels. In conclusion, the present findings demonstrate that the activation of PAR-2 suppresses peripheral sympathetic outflow by modulating N-type Ca2+ channel activity, which appears to be involved in PAR-2-induced hypotension, in peripheral sympathetic nerve terminals. PMID:25410909

  18. Inflammatory mediator bradykinin increases population of sensory neurons expressing functional T-type Ca2+ channels

    PubMed Central

    Huang, Dongyang; Liang, Ce; Zhang, Fan; Men, Hongchao; Du, Xiaona; Gamper, Nikita; Zhang, Hailin

    2016-01-01

    T-type Ca2+ channels are important regulators of peripheral sensory neuron excitability. Accordingly, T-type Ca2+ currents are often increased in various pathological pain conditions, such as inflammation or nerve injury. Here we investigated effects of inflammation on functional expression of T-type Ca2+ channels in small-diameter cultured dorsal root ganglion (DRG) neurons. We found that overnight treatment of DRG cultures with a cocktail of inflammatory mediators bradykinin (BK), adenosine triphosphate (ATP), norepinephrine (NE) and prostaglandin E2 (PGE2) strongly increased the population size of the small-diameter neurons displaying low-voltage activated (LVA, T-type) Ca2+ currents while having no effect on the peak LVA current amplitude. When applied individually, BK and ATP also increased the population size of LVA-positive neurons while NE and PGE2 had no effect. The PLC inhibitor U-73122 and B2 receptor antagonist, Hoe-140, both abolished the increase of the population of LVA-positive DRG neurons. Inflammatory treatment did not affect CaV3.2 mRNA or protein levels in DRG cultures. Furthermore, an ubiquitination inhibitor, MG132, did not increase the population of LVA-positive neurons. Our data suggest that inflammatory mediators BK and ATP increase the abundance of LVA-positive DRG neurons in total neuronal population by stimulating the recruitment of a ‘reserve pool’ of CaV3.2 channels, particularly in neurons that do not display measurable LVA currents under control conditions. PMID:26944020

  19. Distribution of the P2X2 receptor and chemical coding in ileal enteric neurons of obese male mice (ob/ob)

    PubMed Central

    Mizuno, Márcia Sanae; Crisma, Amanda Rabello; Borelli, Primavera; Schäfer, Bárbara Tavares; Silveira, Mariana Póvoa; Castelucci, Patricia

    2014-01-01

    AIM: To investigate the colocalization, density and profile of neuronal areas of enteric neurons in the ileum of male obese mice. METHODS: The small intestinal samples of male mice in an obese group (OG) (C57BL/6J ob/ob) and a control group (CG) (+/+) were used. The tissues were analyzed using a double immunostaining technique for immunoreactivity (ir) of the P2X2 receptor, nitric oxide synthase (NOS), choline acetyl transferase (ChAT) and calretinin (Calr). Also, we investigated the density and profile of neuronal areas of the NOS-, ChAT- and Calr-ir neurons in the myenteric plexus. Myenteric neurons were labeled using an NADH-diaphorase histochemical staining method. RESULTS: The analysis demonstrated that the P2X2 receptor was expressed in the cytoplasm and in the nuclear and cytoplasmic membranes only in the CG. Neuronal density values (neuron/cm2) decreased 31% (CG: 6579 ± 837; OG: 4556 ± 407) and 16.5% (CG: 7796 ± 528; OG: 6513 ± 610) in the NOS-ir and calretinin-ir neurons in the OG, respectively (P < 0.05). Density of ChAT-ir (CG: 6200 ± 310; OG: 8125 ± 749) neurons significantly increased 31% in the OG (P < 0.05). Neuron size studies demonstrated that NOS, ChAT, and Calr-ir neurons did not differ significantly between the CG and OG groups. The examination of NADH-diaphorase-positive myenteric neurons revealed an overall similarity between the OG and CG. CONCLUSION: Obesity may exert its effects by promoting a decrease in P2X2 receptor expression and modifications in the density of the NOS-ir, ChAT-ir and CalR-ir myenteric neurons. PMID:25320527

  20. Endomorphin-2 is Released from Newborn Rat Primary Sensory Neurons in a Frequency- and Calcium- Dependent Manner

    PubMed Central

    Scanlin, Heather L.; Carroll, Elizabeth A.; Jenkins, Victoria K.; Balkowiec, Agnieszka

    2008-01-01

    Recent evidence indicates that endomorphins, endogenous mu-opioid receptor (MOR) agonists, modulate synaptic transmission in both somatic and visceral sensory pathways. Here we show that endomorphin-2 (END-2) is expressed in newborn rat dorsal root ganglion (DRG) and nodose-petrosal ganglion complex (NPG) neurons, and rarely co-localizes with brain-derived neurotrophic factor (BDNF). In order to examine activity-dependent release of END-2 from neurons, we established a model using dispersed cultures of DRG and NPG cells activated by patterned electrical field stimulation. To detect release of END-2, we developed a novel rapid capture ELISA, in which END-2 capture antibody was added to neuronal cultures shortly before their electrical stimulation. The conventional assay was effective at reliably detecting END-2 only when the cells were stimulated in the presence of CTAP, a MOR-selective antagonist. This suggests that the strength of the novel assay is related primarily to rapid capture of released END-2 before it binds to endogenous MORs. Using the rapid capture ELISA, we found that stimulation protocols known to induce plastic changes at sensory synapses were highly effective at releasing END-2. Removal of extracellular calcium or blocking voltage-activated calcium channels significantly reduced the release. Together, our data provide the first evidence that END-2 is expressed by newborn DRG neurons of all sizes found in this age group, and can be released from these, as well as from NPG neurons, in an activity-dependent manner. These results point to END-2 as a likely mediator of activity-dependent plasticity in sensory pathways. PMID:18513316

  1. Hindbrain lactate regulates preoptic gonadotropin-releasing hormone (GnRH) neuron GnRH-I protein but not AMPK responses to hypoglycemia in the steroid-primed ovariectomized female rat.

    PubMed

    Shrestha, P K; Briski, K P

    2015-07-09

    Steroid positive-feedback activation of the gonadotropin-releasing hormone (GnRH)-pituitary luteinizing hormone (LH) neuroendocrine axis propagates the pre ovulatory LH surge, a crucial component of female reproduction. Our work shows that this key event is restrained by inhibitory metabolic input from hindbrain A2 noradrenergic neurons. GnRH neurons express the ultra-sensitive energy sensor adenosine 5'-monophosphate-activated protein kinase (AMPK); here, we investigated the hypothesis that GnRH nerve cell AMPK and peptide neurotransmitter responses to insulin-induced hypoglycemia are controlled by hindbrain lack of the oxidizable glycolytic end-product L-lactate. Data show that hypoglycemic inhibition of LH release in steroid-primed ovariectomized female rats was reversed by coincident caudal hindbrain lactate infusion. Western blot analyses of laser-microdissected A2 neurons demonstrate hypoglycemic augmentation [Fos, estrogen receptor-beta (ER-β), phosphoAMPK (pAMPK)] and inhibition (dopamine-beta-hydroxylase, GLUT3, MCT2) of protein expression in these cells, responses that were normalized by insulin plus lactate treatment. Hypoglycemia diminished rostral preoptic GnRH nerve cell GnRH-I protein and pAMPK content; the former, but not the latter response was reversed by lactate. Results implicate caudal hindbrain lactoprivic signaling in hypoglycemia-induced suppression of the LH surge, demonstrating that lactate repletion of that site reverses decrements in A2 catecholamine biosynthetic enzyme and GnRH neuropeptide precursor protein expression. Lack of effect of lactate on hypoglycemic patterns of GnRH AMPK activity suggests that this sensor is uninvolved in metabolic-inhibition of positive-feedback-stimulated hypophysiotropic signaling to pituitary gonadotropes. Copyright © 2015 IBRO. Published by Elsevier Ltd. All rights reserved.

  2. Screening with an NMNAT2-MSD platform identifies small molecules that modulate NMNAT2 levels in cortical neurons.

    PubMed

    Ali, Yousuf O; Bradley, Gillian; Lu, Hui-Chen

    2017-03-07

    Nicotinamide mononucleotide adenylyl transferase 2 (NMNAT2) is a key neuronal maintenance factor and provides potent neuroprotection in numerous preclinical models of neurological disorders. NMNAT2 is significantly reduced in Alzheimer's, Huntington's, Parkinson's diseases. Here we developed a Meso Scale Discovery (MSD)-based screening platform to quantify endogenous NMNAT2 in cortical neurons. The high sensitivity and large dynamic range of this NMNAT2-MSD platform allowed us to screen the Sigma LOPAC library consisting of 1280 compounds. This library had a 2.89% hit rate, with 24 NMNAT2 positive and 13 negative modulators identified. Western analysis was conducted to validate and determine the dose-dependency of identified modulators. Caffeine, one identified NMNAT2 positive-modulator, when systemically administered restored NMNAT2 expression in rTg4510 tauopathy mice to normal levels. We confirmed in a cell culture model that four selected positive-modulators exerted NMNAT2-specific neuroprotection against vincristine-induced cell death while four selected NMNAT2 negative modulators reduced neuronal viability in an NMNAT2-dependent manner. Many of the identified NMNAT2 positive modulators are predicted to increase cAMP concentration, suggesting that neuronal NMNAT2 levels are tightly regulated by cAMP signaling. Taken together, our findings indicate that the NMNAT2-MSD platform provides a sensitive phenotypic screen to detect NMNAT2 in neurons.

  3. Screening with an NMNAT2-MSD platform identifies small molecules that modulate NMNAT2 levels in cortical neurons

    PubMed Central

    Ali, Yousuf O.; Bradley, Gillian; Lu, Hui-Chen

    2017-01-01

    Nicotinamide mononucleotide adenylyl transferase 2 (NMNAT2) is a key neuronal maintenance factor and provides potent neuroprotection in numerous preclinical models of neurological disorders. NMNAT2 is significantly reduced in Alzheimer’s, Huntington’s, Parkinson’s diseases. Here we developed a Meso Scale Discovery (MSD)-based screening platform to quantify endogenous NMNAT2 in cortical neurons. The high sensitivity and large dynamic range of this NMNAT2-MSD platform allowed us to screen the Sigma LOPAC library consisting of 1280 compounds. This library had a 2.89% hit rate, with 24 NMNAT2 positive and 13 negative modulators identified. Western analysis was conducted to validate and determine the dose-dependency of identified modulators. Caffeine, one identified NMNAT2 positive-modulator, when systemically administered restored NMNAT2 expression in rTg4510 tauopathy mice to normal levels. We confirmed in a cell culture model that four selected positive-modulators exerted NMNAT2-specific neuroprotection against vincristine-induced cell death while four selected NMNAT2 negative modulators reduced neuronal viability in an NMNAT2-dependent manner. Many of the identified NMNAT2 positive modulators are predicted to increase cAMP concentration, suggesting that neuronal NMNAT2 levels are tightly regulated by cAMP signaling. Taken together, our findings indicate that the NMNAT2-MSD platform provides a sensitive phenotypic screen to detect NMNAT2 in neurons. PMID:28266613

  4. In vivo clonal overexpression of neuroligin 3 and neuroligin 2 in neurons of the rat cerebral cortex. Differential effects on GABAergic synapses and neuronal migration

    PubMed Central

    Fekete, Christopher D.; Chiou, Tzu-Ting; Miralles, Celia P.; Harris, Rachel S.; Fiondella, Christopher G.; LoTurco, Joseph J.; De Blas, Angel L.

    2015-01-01

    We have studied the effect of clonal overexpression of neuroligin 3 (NL3) or neuroligin 2 (NL2) in the adult rat cerebral cortex following in utero electroporation (IUEP) at embryonic stage E14. Overexpression of NL3 leads to a large increase in vGAT and GAD65 in the GABAergic contacts that the overexpressing neurons receive. Overexpression of NL2 produced a similar effect but to a lesser extent. In contrast, overexpression of NL3 or NL2 after IUEP, does not affect vGlut1 in the glutamatergic contacts that the NL3 or NL2 overexpressing neurons receive. The NL3 or NL2 overexpressing neurons do not show increased innervation by parvalbumin-containing GABAergic terminals or increased parvalbumin in the same terminals that show increased vGAT. These results indicate that the observed increase in vGAT and GAD65 is not due to increased GABAergic innervation but to increased expression of vGAT and GAD65 in the GABAergic contacts that NL3 or NL2 overexpressing neurons receive. The majority of bright vGAT puncta contacting the NL3 overexpressing neurons have no gephyrin juxtaposed to them indicating that many of these contacts are non-synaptic. This contrasts with the majority of the NL2 overexpressing neurons, which show plenty of synaptic gephyrin clusters juxtaposed to vGAT. Besides having an effect on GABAergic contacts, overexpression of NL3 interferes with the neuronal radial migration, in the cerebral cortex, of the neurons overexpressing NL3. PMID:25565602

  5. Gravin orchestrates PKA and β2-adrenergic receptor signaling critical for synaptic plasticity and memory

    PubMed Central

    Havekes, Robbert; Canton, David A.; Park, Alan J.; Huang, Ted; Nie, Ting; Day, Jonathan P.; Guercio, Leonardo A.; Grimes, Quinn; Luczak, Vincent; Gelman, Irwin H.; Baillie, George S.; Scott, John D.; Abel, Ted

    2012-01-01

    A kinase-anchoring proteins (AKAPs) organize compartmentalized pools of Protein Kinase A (PKA) to enable localized signaling events within neurons. However, it is unclear which of the many expressed AKAPs in neurons target PKA to signaling complexes important for long-lasting forms of synaptic plasticity and memory storage. In the forebrain, the anchoring protein gravin recruits a signaling complex containing PKA, PKC, calmodulin, and PDE4D to the β2-adrenergic receptor. Here, we show that mice lacking the α-isoform of gravin have deficits in PKA-dependent long-lasting forms of hippocampal synaptic plasticity including β2-adrenergic receptor-mediated plasticity, and selective impairments of long-term memory storage. Further, both hippocampal β2-adrenergic receptor phosphorylation by PKA, and learning-induced activation of ERK, are attenuated in the CA1 region of the hippocampus in mice lacking gravin-α. We conclude that gravin compartmentalizes a significant pool of PKA that regulates learning-induced β2-adrenergic receptor signaling and ERK activation in the hippocampus in vivo, organizing molecular interactions between glutamatergic and noradrenergic signaling pathways for long-lasting synaptic plasticity, and memory storage. PMID:23238728

  6. Downregulation of PMCA2 increases the vulnerability of midbrain neurons to mitochondrial complex I inhibition.

    PubMed

    Brendel, Alexander; Renziehausen, Jana; Behl, Christian; Hajieva, Parvana

    2014-01-01

    Parkinson's disease is an age-associated disorder characterized by selective degeneration of dopaminergic neurons. The molecular mechanisms underlying the selective vulnerability of this subset of neurons are, however, not fully understood. Employing SH-SY5Y neuroblastoma cells and primary mesencephalic neurons, we here demonstrate a significant increase in cytosolic calcium after inhibition of mitochondrial complex I by means of MPP(+), which is a well-established environmental toxin-based in vitro model of Parkinson's disease. This increase in calcium is correlated with a downregulation of the neuron-specific plasma membrane Ca(2+)-ATPase isoform 2 (PMCA2). Interestingly, two other important mediators of calcium efflux, sarcoplasmic reticulum Ca(2+)-ATPase (SERCA), and Na(+)-Ca(2+)-exchanger (NCX), remained unaltered, indicating a specific role of PMCA2 in maintaining calcium homeostasis in neurons. The observed PMCA2 downregulation was accompanied by reduced levels of phosphorylated CREB protein, an intracellular signaling molecule and transcriptional regulator. In order to investigate the potential influence of PMCA2 on neuronal vulnerability, experimental downregulation of PMCA2 by means of siRNA was performed. The results demonstrate a significant impairment of cell survival under conditions of PMCA2 suppression. Hence, in our cell models increased cytosolic calcium levels as a consequence of insufficient calcium efflux lead to an increased vulnerability of neuronal cells. Moreover, overexpression of PMCA2 rendered the neurons significantly resistant to complex I inhibition. Our findings point toward a dysregulation of calcium homeostasis in Parkinson's disease and suggest a potential molecular mechanism of neurodegeneration via PMCA2. Copyright © 2013 Elsevier Inc. All rights reserved.

  7. A Viral Receptor Complementation Strategy to Overcome CAV-2 Tropism for Efficient Retrograde Targeting of Neurons.

    PubMed

    Li, Shu-Jing; Vaughan, Alexander; Sturgill, James Fitzhugh; Kepecs, Adam

    2018-06-06

    Retrogradely transported neurotropic viruses enable genetic access to neurons based on their long-range projections and have become indispensable tools for linking neural connectivity with function. A major limitation of viral techniques is that they rely on cell-type-specific molecules for uptake and transport. Consequently, viruses fail to infect variable subsets of neurons depending on the complement of surface receptors expressed (viral tropism). We report a receptor complementation strategy to overcome this by potentiating neurons for the infection of the virus of interest-in this case, canine adenovirus type-2 (CAV-2). We designed AAV vectors for expressing the coxsackievirus and adenovirus receptor (CAR) throughout candidate projection neurons. CAR expression greatly increased retrograde-labeling rates, which we demonstrate for several long-range projections, including some resistant to other retrograde-labeling techniques. Our results demonstrate a receptor complementation strategy to abrogate endogenous viral tropism and thereby facilitate efficient retrograde targeting for functional analysis of neural circuits. Copyright © 2018 Elsevier Inc. All rights reserved.

  8. MCT2 Expression and Lactate Influx in Anorexigenic and Orexigenic Neurons of the Arcuate Nucleus

    PubMed Central

    Cortes-Campos, Christian; Elizondo, Roberto; Carril, Claudio; Martínez, Fernando; Boric, Katica; Nualart, Francisco; Garcia-Robles, Maria Angeles

    2013-01-01

    Hypothalamic neurons of the arcuate nucleus control food intake, releasing orexigenic and anorexigenic neuropeptides in response to changes in glucose concentration. Several studies have suggested that the glucosensing mechanism is governed by a metabolic interaction between neurons and glial cells via lactate flux through monocarboxylate transporters (MCTs). Hypothalamic glial cells (tanycytes) release lactate through MCT1 and MCT4; however, similar analyses in neuroendocrine neurons have yet to be undertaken. Using primary rat hypothalamic cell cultures and fluorimetric assays, lactate incorporation was detected. Furthermore, the expression and function of MCT2 was demonstrated in the hypothalamic neuronal cell line, GT1-7, using kinetic and inhibition assays. Moreover, MCT2 expression and localization in the Sprague Dawley rat hypothalamus was analyzed using RT-PCR, in situ hybridization and Western blot analyses. Confocal immunohistochemistry analyses revealed MCT2 localization in neuronal but not glial cells. Moreover, MCT2 was localized to ∼90% of orexigenic and ∼60% of anorexigenic neurons as determined by immunolocalization analysis of AgRP and POMC with MCT2-positives neurons. Thus, MCT2 distribution coupled with lactate uptake by hypothalamic neurons suggests that hypothalamic neurons control food intake using lactate to reflect changes in glucose levels. PMID:23638108

  9. Designer Receptors Enhance Memory in a Mouse Model of Down Syndrome

    PubMed Central

    Fortress, Ashley M.; Hamlett, Eric D.; Vazey, Elena M.; Aston-Jones, Gary; Cass, Wayne A.; Boger, Heather A.

    2015-01-01

    Designer receptors exclusively activated by designer drugs (DREADDs) are novel and powerful tools to investigate discrete neuronal populations in the brain. We have used DREADDs to stimulate degenerating neurons in a Down syndrome (DS) model, Ts65Dn mice. Individuals with DS develop Alzheimer's disease (AD) neuropathology and have elevated risk for dementia starting in their 30s and 40s. Individuals with DS often exhibit working memory deficits coupled with degeneration of the locus coeruleus (LC) norepinephrine (NE) neurons. It is thought that LC degeneration precedes other AD-related neuronal loss, and LC noradrenergic integrity is important for executive function, working memory, and attention. Previous studies have shown that LC-enhancing drugs can slow the progression of AD pathology, including amyloid aggregation, oxidative stress, and inflammation. We have shown that LC degeneration in Ts65Dn mice leads to exaggerated memory loss and neuronal degeneration. We used a DREADD, hM3Dq, administered via adeno-associated virus into the LC under a synthetic promoter, PRSx8, to selectively stimulate LC neurons by exogenous administration of the inert DREADD ligand clozapine-N-oxide. DREADD stimulation of LC-NE enhanced performance in a novel object recognition task and reduced hyperactivity in Ts65Dn mice, without significant behavioral effects in controls. To confirm that the noradrenergic transmitter system was responsible for the enhanced memory function, the NE prodrug l-threo-dihydroxyphenylserine was administered in Ts65Dn and normosomic littermate control mice, and produced similar behavioral results. Thus, NE stimulation may prevent memory loss in Ts65Dn mice, and may hold promise for treatment in individuals with DS and dementia. PMID:25632113

  10. Autoradiographic analysis of alpha 1-noradrenergic receptors in the human brain postmortem. Effect of suicide

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gross-Isseroff, R.; Dillon, K.A.; Fieldust, S.J.

    In vitro quantitative autoradiography of alpha 1-noradrenergic receptors, using tritiated prazosin as a ligand, was performed on 24 human brains postmortem. Twelve brains were obtained from suicide victims and 12 from matched controls. We found significant lower binding to alpha 1 receptors in several brain regions of the suicide group as compared with matched controls. This decrease in receptor density was evident in portions of the prefrontal cortex, as well as the temporal cortex and in the caudate nucleus. Age, sex, presence of alcohol, and time of death to autopsy did not affect prazosin binding, in our sample, as measuredmore » by autoradiography.« less

  11. Noradrenaline decreases spike voltage threshold and induces electrographic sharp waves in turtle medial cortex in vitro.

    PubMed

    Lorenzo, Daniel; Velluti, Julio C

    2004-01-01

    The noradrenergic modulation of neuronal properties has been described at different levels of the mammalian brain. Although the anatomical characteristics of the noradrenergic system are well known in reptiles, functional data are scarce. In our study the noradrenergic modulation of cortical electrogenesis in the turtle medial cortex was studied in vitro using a combination of field and intracellular recordings. Turtle EEG consists of a low voltage background interspersed by spontaneous large sharp waves (LSWs). Noradrenaline (NA, 5-40 microM) induced (or enhanced) the generation of LSWs in a dose-dependent manner. Pharmacological experiments suggest the participation of alpha and beta receptors in this effect. In medial cortex neurons NA induced a hyperpolarization of the resting potential and a decrease of input resistance. Both effects were observed also after TTX treatment. Noradrenaline increased the response of the cells to depolarizing pulses, resulting in an upward shift of the frequency/current relation. In most cells the excitability change was mediated by a decrease of the spike voltage threshold resulting in the reduction of the amount of depolarization needed to fire the cell (voltage threshold minus resting potential). As opposed to the mechanisms reported in mammalian neurons, no changes in the frequency adaptation or the post-train afterhyperpolarization were observed. The NA effects at the cellular level were not reproduced by noradrenergic agonists. Age- and species-dependent properties in the pharmacology of adrenergic receptors could be involved in this result. Cellular effects of NA in turtle cortex are similar to those described in mammals, although the increase in cellular excitability seems to be mediated by a different mechanism. Copyright 2004 S. Karger AG, Basel

  12. Characterization of Na+ and Ca2+ Channels in Zebrafish Dorsal Root Ganglion Neurons

    PubMed Central

    Won, Yu-Jin; Ono, Fumihito; Ikeda, Stephen R.

    2012-01-01

    Background Dorsal root ganglia (DRG) somata from rodents have provided an excellent model system to study ion channel properties and modulation using electrophysiological investigation. As in other vertebrates, zebrafish (Danio rerio) DRG are organized segmentally and possess peripheral axons that bifurcate into each body segment. However, the electrical properties of zebrafish DRG sensory neurons, as compared with their mammalian counterparts, are relatively unexplored because a preparation suitable for electrophysiological studies has not been available. Methodology/Principal Findings We show enzymatically dissociated DRG neurons from juvenile zebrafish expressing Isl2b-promoter driven EGFP were easily identified with fluorescence microscopy and amenable to conventional whole-cell patch-clamp studies. Two kinetically distinct TTX-sensitive Na+ currents (rapidly- and slowly-inactivating) were discovered. Rapidly-inactivating INa were preferentially expressed in relatively large neurons, while slowly-inactivating INa was more prevalent in smaller DRG neurons. RT-PCR analysis suggests zscn1aa/ab, zscn8aa/ab, zscn4ab and zscn5Laa are possible candidates for these INa components. Voltage-gated Ca2+ currents (ICa) were primarily (87%) comprised of a high-voltage activated component arising from ω-conotoxin GVIA-sensitive CaV2.2 (N-type) Ca2+ channels. A few DRG neurons (8%) displayed a miniscule low-voltage-activated component. ICa in zebrafish DRG neurons were modulated by neurotransmitters via either voltage-dependent or -independent G-protein signaling pathway with large cell-to-cell response variability. Conclusions/Significance Our present results indicate that, as in higher vertebrates, zebrafish DRG neurons are heterogeneous being composed of functionally distinct subpopulations that may correlate with different sensory modalities. These findings provide the first comparison of zebrafish and rodent DRG neuron electrical properties and thus provide a basis for

  13. Chemosensitive Phox2b-expressing neurons are crucial for hypercapnic ventilatory response in the nucleus tractus solitarius.

    PubMed

    Fu, Congrui; Xue, Jinyu; Wang, Ri; Chen, Jinting; Ma, Lan; Liu, Yixian; Wang, Xuejiao; Guo, Fang; Zhang, Yi; Zhang, Xiangjian; Wang, Sheng

    2017-07-15

    Central hypercapnic hypoventilation is highly prevalent in children suffering from congenital central hypoventilation syndrome (CCHS). Mutations of the gene for paired-like homeobox 2b (Phox2b) are aetiologically associated with CCHS and Phox2b is present in central components of respiratory chemoreflex, such as the nucleus tractus solitarius (NTS). Injection of the neurotoxin substance P-saporin into NTS destroys Phox2b-expressing neurons. Impaired hypercapnic ventilatory response caused by this neurotoxin is attributable to a loss of CO 2 -sensitive Phox2b-expressing NTS neurons. A subgroup of Phox2b-expressing neurons exhibits intrinsic chemosensitivity. A background K + channel-like current is partially responsible for such chemosensitivity in Phox2b-expressing neurons. The present study helps us better understand the mechanism of respiratory deficits in CCHS and potentially locates a brainstem site for development of precise clinical intervention. The nucleus tractus solitarius (NTS) neurons have been considered to function as central respiratory chemoreceptors. However, the common molecular marker defined for these neurons remains unknown. The present study investigated whether paired-like homeobox 2b (Phox2b)-expressing NTS neurons are recruited in hypercapnic ventilatory response (HCVR) and whether these neurons exhibit intrinsic chemosensitivity. HCVR was assessed using whole body plethysmography and neuronal chemosensitivity was examined by patch clamp recordings in brainstem slices or dissociated neurons from Phox2b-EGFP transgenic mice. Injection of the neurotoxin substance P-saporin (SSP-SAP) into NTS destroyed Phox2b-expressing neurons. Minute ventilation and tidal volume were both reduced by 13% during exposure to 8% CO 2 in inspired air when ∼13% of the Phox2b-expressing neurons were eliminated. However, a loss of ∼18% of these neurons was associated with considerable decreases in minute ventilation by ≥18% and in tidal volume by≥22% when

  14. Effects of endogenous pyrogen and prostaglandin E2 on hypothalamic neurons in rat brain slices.

    PubMed

    Watanabe, T; Morimoto, A; Murakami, N

    1987-06-01

    We investigated the effects of endogenous pyrogen and prostaglandin E2 (PGE2) on the preoptic and anterior hypothalamic (POAH) neurons using brain slice preparations from the rat. Partially purified endogenous pyrogen did not change the activities of most of the neurons in the POAH region when applied locally through a micropipette attached to the recording electrode in proximity to the neurons. This indicates that partially purified endogenous pyrogen does not act directly on the neuronal activity in the POAH region. The partially purified endogenous pyrogen, applied into a culture chamber containing a brain slice, facilitated the activities in 24% of the total neurons tested, regardless of the thermal specificity of the neurons. Moreover, PGE2 added to the culture chamber facilitated 48% of the warm-responsive, 33% of the cold-responsive, and 29% of the thermally insensitive neurons. The direction of change in neuronal activity induced by partially purified endogenous pyrogen appears to be almost the same as that induced by PGE2 when these substances were applied by perfusion to the same neuron in the culture chamber. These results suggest that partially purified pyrogen applied to the perfusate of the culture chamber stimulates some constituents of brain tissue to synthesize and release prostaglandin, which in turn affects the neuronal activity of the POAH region.

  15. 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.

  16. Late onset GM2 gangliosidosis presenting with motor neuron disease: an autopsy case.

    PubMed

    Yokoyama, Teruo; Nakamura, Seigo; Horiuchi, Emiko; Ishiyama, Miyako; Kawashima, Rei; Nakamura, Kazuo; Hasegawa, Kazuko; Yagishita, Saburo

    2014-06-01

    Adult-onset GM2 gangliosidosis is very rare and only three autopsy cases have been reported up to now. We report herein an autopsy case of adult-onset GM2 gangliosidosis. The patient developed slowly progressive motor neuron disease-like symptoms after longstanding mood disorder and cognitive dysfunction. He developed gait disturbance and weakness of lower limbs at age 52 years. Because of progressive muscle weakness and atrophy, he became bed-ridden at age 65. At age of 68, he died. His neurological findings presented slight cognitive disturbance, slight manic state, severe muscle weakness, atrophy of four limbs and no extrapyramidal signs and symptoms, and cerebellar ataxia. Neuropathologically, mild neuronal loss and abundant lipid deposits were noted in the neuronal cytoplasm throughout the nervous system, including peripheral autonomic neurons. The most outstanding findings were marked neuronal loss and distended neurons in the anterior horn of the spinal cord, which supports his clinical symptomatology of lower motor neuron disease in this case. The presence of lipofuscin, zebra bodies and membranous cytoplasmic bodies (MCB) and the increase of GM2 ganglioside by biochemistry led to diagnosis of GM2 gangliosidosis. © 2013 Japanese Society of Neuropathology.

  17. Photostimulation of Phox2b medullary neurons activates cardiorespiratory function in conscious rats.

    PubMed

    Kanbar, Roy; Stornetta, Ruth L; Cash, Devin R; Lewis, Stephen J; Guyenet, Patrice G

    2010-11-01

    Hypoventilation is typically treated with positive pressure ventilation or, in extreme cases, by phrenic nerve stimulation. This preclinical study explores whether direct stimulation of central chemoreceptors could be used as an alternative method to stimulate breathing. To determine whether activation of the retrotrapezoid nucleus (RTN), which is located in the rostral ventrolateral medulla (RVLM), stimulates breathing with appropriate selectivity. A lentivirus was used to induce expression of the photoactivatable cationic channel channelrhodopsin-2 (ChR2) by RVLM Phox2b-containing neurons, a population that consists of central chemoreceptors (the ccRTN neurons) and blood pressure (BP)-regulating neurons (the C1 cells). The transfected neurons were activated with pulses of laser light. Respiratory effects were measured by plethysmography or diaphragmatic EMG recording and cardiovascular effects by monitoring BP, renal sympathetic nerve discharge, and the baroreflex. The RVLM contained 600 to 900 ChR2-transfected neurons (63% C1, 37% ccRTN). RVLM photostimulation significantly increased breathing rate (+42%), tidal volume (21%), minute volume (68%), and peak expiratory flow (48%). Photostimulation increased diaphragm EMG amplitude (19%) and frequency (21%). Photostimulation increased BP (4 mmHg) and renal sympathetic nerve discharge (43%) while decreasing heart rate (15 bpm). Photostimulation of ChR2-transfected RVLM Phox2b neurons produces a vigorous stimulation of breathing accompanied by a small sympathetically mediated increase in BP. These results demonstrate that breathing can be relatively selectively activated in resting unanesthetized mammals via optogenetic manipulation of RVLM neurons presumed to be central chemoreceptors. This methodology could perhaps be used in the future to enhance respiration in humans.

  18. Photostimulation of Phox2b Medullary Neurons Activates Cardiorespiratory Function in Conscious Rats

    PubMed Central

    Kanbar, Roy; Stornetta, Ruth L.; Cash, Devin R.; Lewis, Stephen J.; Guyenet, Patrice G.

    2010-01-01

    Rationale: Hypoventilation is typically treated with positive pressure ventilation or, in extreme cases, by phrenic nerve stimulation. This preclinical study explores whether direct stimulation of central chemoreceptors could be used as an alternative method to stimulate breathing. Objectives: To determine whether activation of the retrotrapezoid nucleus (RTN), which is located in the rostral ventrolateral medulla (RVLM), stimulates breathing with appropriate selectivity. Methods: A lentivirus was used to induce expression of the photoactivatable cationic channel channelrhodopsin-2 (ChR2) by RVLM Phox2b-containing neurons, a population that consists of central chemoreceptors (the ccRTN neurons) and blood pressure (BP)-regulating neurons (the C1 cells). The transfected neurons were activated with pulses of laser light. Respiratory effects were measured by plethysmography or diaphragmatic EMG recording and cardiovascular effects by monitoring BP, renal sympathetic nerve discharge, and the baroreflex. Measurements and Main Results: The RVLM contained 600 to 900 ChR2-transfected neurons (63% C1, 37% ccRTN). RVLM photostimulation significantly increased breathing rate (+42%), tidal volume (21%), minute volume (68%), and peak expiratory flow (48%). Photostimulation increased diaphragm EMG amplitude (19%) and frequency (21%). Photostimulation increased BP (4 mmHg) and renal sympathetic nerve discharge (43%) while decreasing heart rate (15 bpm). Conclusions: Photostimulation of ChR2-transfected RVLM Phox2b neurons produces a vigorous stimulation of breathing accompanied by a small sympathetically mediated increase in BP. These results demonstrate that breathing can be relatively selectively activated in resting unanesthetized mammals via optogenetic manipulation of RVLM neurons presumed to be central chemoreceptors. This methodology could perhaps be used in the future to enhance respiration in humans. PMID:20622037

  19. FoxP2 brainstem neurons project to sodium appetite regulatory sites.

    PubMed

    Shin, Jung-Won; Geerling, Joel C; Stein, Matthew K; Miller, Rebecca L; Loewy, Arthur D

    2011-09-01

    The transcription factor Forkhead box protein 2 (FoxP2) is expressed in two cell groups of the brainstem that have been implicated in sodium appetite regulation: the pre-locus coeruleus (pre-LC) and parabrachial nucleus--external lateral-inner subdivision (PBel-inner). Because the connections of these two groups are unknown, neuroanatomical tracing methods were used to define their central projections. The pre-LC outputs were first analyzed using an anterograde axonal tracer--Phaseolus vulgaris leucoagglutinin (PHAL) to construct a brain map. Next, we examined whether the FoxP2 immunoreactive (FoxP2+) neurons of the pre-LC contribute to these projections using a retrograde neuronal tracer--cholera toxin β-subunit (CTb). CTb was injected into selected brain regions identified in the anterograde tracing study. One week later the rats were killed, and brainstem sections were processed by a double immunohistochemical procedure to determine whether the FoxP2+ neurons in the pre-LC and/or PBel-inner contained CTb. FoxP2+ pre-LC neurons project to: (1) ventral pallidum; (2) substantia innominata and bed nucleus of the stria terminalis; (3) paraventricular, central medial, parafascicular, and subparafascicular parvicellular thalamic nuclei; (4) paraventricular (PVH), lateral, perifornical, dorsomedial (DMH), and parasubthalamic hypothalamic nuclei; and (5) ventral tegmental area (VTA), periaqueductal gray matter (PAG), dorsal and central linear raphe nuclei. FoxP2+ PBel-inner neurons project to the PVH and DMH, with weaker connections to the LHA, VTA, and PAG. Both the pre-LC and PBel-inner project to central sites implicated in sodium appetite, and related issues, including foraging behavior, hedonic responses to salt intake, sodium balance, and cardiovascular regulation, are discussed. Copyright © 2011 Elsevier B.V. All rights reserved.

  20. Bilateral thoracoscopic splanchnicectomy for pain in patients with chronic pancreatitis impairs adrenomedullary but not noradrenergic sympathetic function.

    PubMed

    Buscher, H C J L; Lenders, J W M; Wilder-Smith, O H G; Sweep, C G J; van Goor, H

    2012-08-01

    Bilateral thoracoscopic splanchnicectomy (BTS) is a well-known technique to alleviate intractable pain in patients with chronic pancreatitis. BTS not only disrupts afferent fibers from the pancreas that mediate pain but also postganglionic sympathetic fibers, which originate in segments T5-T12 and which innervate the vasculature of the liver, pancreas, and the adrenal gland. The purpose of this study was to assess whether and how BTS affects sympathetic noradrenergic and adrenomedullary function in patients with chronic pancreatitis. Sixteen patients with chronic pancreatitis for at least 1 year underwent autonomic function testing before and 6 weeks after BTS for intractable pain. Testing was performed during supine rest and during sympathetic stimulation when standing. Supine and standing systolic and diastolic blood pressure were significantly lower post-BTS compared with pre-BTS (P = 0.001). One patient showed orthostatic hypotension after BTS. Baseline plasma norepinephrine levels and plasma norepinephrine responses to sympathetic activation during standing were not reduced by BTS. In contrast, supine plasma epinephrine levels and responses during standing were significantly reduced (P < 0.001). Parasympathetic activity was unaffected by BTS as shown by unaltered Valsalva ratio, I-E difference, and ΔHRmax. BTS for pain relief in patients with chronic pancreatitis reduced adrenomedullary function, due to disruption of the efferent sympathetic fibers to the adrenal gland. BTS did not affect noradrenergic sympathetic activity, although blood pressure was lower after the sympathectomy.

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

    PubMed

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

    2014-05-01

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

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Son, Tae Gen; Kawamoto, Elisa M.; Yu, Qian-Sheng

    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 andmore » glial cultures, and protects neurons against glutamate-induced excitotoxicity.« less

  3. A chimeric path to neuronal synchronization

    NASA Astrophysics Data System (ADS)

    Essaki Arumugam, Easwara Moorthy; Spano, Mark L.

    2015-01-01

    Synchronization of neuronal activity is associated with neurological disorders such as epilepsy. This process of neuronal synchronization is not fully understood. To further our understanding, we have experimentally studied the progression of this synchronization from normal neuronal firing to full synchronization. We implemented nine FitzHugh-Nagumo neurons (a simplified Hodgkin-Huxley model) via discrete electronics. For different coupling parameters (synaptic strengths), the neurons in the ring were either unsynchronized or completely synchronized when locally coupled in a ring. When a single long-range connection (nonlocal coupling) was introduced, an intermediate state known as a chimera appeared. The results indicate that (1) epilepsy is likely not only a dynamical disease but also a topological disease, strongly tied to the connectivity of the underlying network of neurons, and (2) the synchronization process in epilepsy may not be an "all or none" phenomenon, but can pass through an intermediate stage (chimera).

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

    PubMed Central

    Eliava, Marina; Melchior, Meggane; Knobloch-Bollmann, H. Sophie; Wahis, Jérôme; Gouveia, Miriam da Silva; Tang, Yan; Ciobanu, Alexandru Cristian; del Rio, Rodrigo Triana; 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

    2017-01-01

    SUMMARY 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. PMID:26948889

  5. 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. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. Homeodomain interacting protein kinase 2 regulates postnatal development of enteric dopaminergic neurons and glia via BMP signaling.

    PubMed

    Chalazonitis, Alcmène; Tang, Amy A; Shang, Yulei; Pham, Tuan D; Hsieh, Ivy; Setlik, Wanda; Gershon, Michael D; Huang, Eric J

    2011-09-28

    Trophic factor signaling is important for the migration, differentiation, and survival of enteric neurons during development. The mechanisms that regulate the maturation of enteric neurons in postnatal life, however, are poorly understood. Here, we show that transcriptional cofactor HIPK2 (homeodomain interacting protein kinase 2) is required for the maturation of enteric neurons and for regulating gliogenesis during postnatal development. Mice lacking HIPK2 display a spectrum of gastrointestinal (GI) phenotypes, including distention of colon and slowed GI transit time. Although loss of HIPK2 does not affect the enteric neurons in prenatal development, a progressive loss of enteric neurons occurs during postnatal life in Hipk2(-/-) mutant mice that preferentially affects the dopaminergic population of neurons in the caudal region of the intestine. The mechanism by which HIPK2 regulates postnatal enteric neuron development appears to involve the response of enteric neurons to bone morphogenetic proteins (BMPs). Specifically, compared to wild type mice, a larger proportion of enteric neurons in Hipk2(-/-) mutants have an abnormally high level of phosphorylated Smad1/5/8. Consistent with the ability of BMP signaling to promote gliogenesis, Hipk2(-/-) mutants show a significant increase in glia in the enteric nervous system. In addition, numbers of autophagosomes are increased in enteric neurons in Hipk2(-/-) mutants, and synaptic maturation is arrested. These results reveal a new role for HIPK2 as an important transcriptional cofactor that regulates the BMP signaling pathway in the maintenance of enteric neurons and glia, and further suggest that HIPK2 and its associated signaling mechanisms may be therapeutically altered to promote postnatal neuronal maturation.

  7. Spatio-temporal characterization imaging of Ca2+ oscillations in rat hippocampal neurons

    NASA Astrophysics Data System (ADS)

    Zhang, Zhihong; Lu, Jinling; Zhou, Wei; Liu, Rengang; Zeng, Shaoqun; Luo, Qingming

    2001-08-01

    Ca2+ is the most common signal transduction element in cells and plays critical rolls in neuronal development and plasticity. Ca2+ signals encode information in their oscillation frequency or amplitude and response time to regular cellular function. In this study, in order to reveal the spatio-temporal characterization of Ca2+ oscillations in rat hippocampal neurons, two kinds of Ca2+ fluorescent probes, yellow cameleons 2.1 (YC2.1) and Fluo-3, were used to monitor the change of the intracellular free Ca2+ concentration (]Ca2+[i). Spontaneous Ca2+ oscillations and glutamate elicited Ca2+ oscillations were observed with multi-photon excitation laser scan microscope (MPELSM) and confocal laser scan microscope (CLSM). The observation showed that the spatio- temporal characterization of either spontaneous or glutamate provoked Ca2+ oscillations had difference between the neurites and somata in individual nerons, especially in some distal end of neurites. The result indicated that Ca2+ oscillations were most important signal transduction pattern in neuronal development and activation. The spatio-temporal characterization of difference of Ca2+ signals between the distal endo of neurites and the somata might be associated with the distribution of ionotropic receptor and metabotropic glutamate receptors, and Ca2+ response mechanism mediated by two kinds of glutamate receptor. Ca2+ signal elicited by glutamate in the distal end of neurites appeared more complex and generated faster than that in the somata. It was suggested that Ca2+ signal in glutamate stimulated hippacamal neurons first generated from the distal end of neurites and then transduted to the somata. The complicated Ca2+ signal characterization in the distal end of neurites might be associated with neuronal activitation, neurotransmitter releasing, and other functions of neurons.

  8. Neuronal-specific endoplasmic reticulum Mg(2+)/Ca(2+) ATPase Ca(2+) sequestration in mixed primary hippocampal culture homogenates.

    PubMed

    Parsons, J Travis; Sun, David A; DeLorenzo, Robert J; Churn, Severn B

    2004-07-01

    Endoplasmic reticulum Mg(2+)/Ca(2+) ATPase Ca(2+) sequestration is crucial for maintenance of neuronal Ca(2+) homeostasis. The use of cell culture in conjunction with modern Ca(2+) imaging techniques has been invaluable in elucidating these mechanisms. While imaging protocols evaluate endoplasmic reticulum Ca(2+) loads, measurement of Mg(2+)/Ca(2+) ATPase activity is indirect, comparing cytosolic Ca(2+) levels in the presence or absence of the Mg(2+)/Ca(2+) ATPase inhibitor thapsigargin. Direct measurement of Mg(2+)/Ca(2+) ATPase by isolation of microsomes is impossible due to the minuscule amounts of protein yielded from cultures used for imaging. In the current study, endoplasmic reticulum Mg(2+)/Ca(2+) ATPase Ca(2+) sequestration was measured in mixed homogenates of neurons and glia from primary hippocampal cultures. It was demonstrated that Ca(2+) uptake was mediated by the endoplasmic reticulum Mg(2+)/Ca(2+) ATPase due to its dependence on ATP and Mg(2+), enhancement by oxalate, and inhibition by thapsigargin. It was also shown that neuronal Ca(2+) uptake, mediated by the type 2 sarco(endo)plasmic reticulum Ca(2+) ATPase isoform, could be distinguished from glial Ca(2+) uptake in homogenates composed of neurons and glia. Finally, it was revealed that Ca(2+) uptake was sensitive to incubation on ice, extremely labile in the absence of protease inhibitors, and significantly more stable under storage conditions at -80 degrees C.

  9. Protein kinase A-induced internalization of Slack channels from the neuronal membrane occurs by adaptor protein-2/clathrin-mediated endocytosis.

    PubMed

    Gururaj, Sushmitha; Evely, Katherine M; Pryce, Kerri D; Li, Jun; Qu, Jun; Bhattacharjee, Arin

    2017-11-24

    The sodium-activated potassium (K Na ) channel Kcnt1 (Slack) is abundantly expressed in nociceptor (pain-sensing) neurons of the dorsal root ganglion (DRG), where they transmit the large outward conductance I KNa and arbitrate membrane excitability. Slack channel expression at the DRG membrane is necessary for their characteristic firing accommodation during maintained stimulation, and reduced membrane channel density causes hyperexcitability. We have previously shown that in a pro-inflammatory state, a decrease in membrane channel expression leading to reduced Slack-mediated I KNa expression underlies DRG neuronal sensitization. An important component of the inflammatory milieu, PKA internalizes Slack channels from the DRG membrane, reduces I KNa , and produces DRG neuronal hyperexcitability when activated in cultured primary DRG neurons. Here, we show that this PKA-induced retrograde trafficking of Slack channels also occurs in intact spinal cord slices and that it is carried out by adaptor protein-2 (AP-2) via clathrin-mediated endocytosis. We provide mass spectrometric and biochemical evidence of an association of native neuronal AP-2 adaptor proteins with Slack channels, facilitated by a dileucine motif housed in the cytoplasmic Slack C terminus that binds AP-2. By creating a competitive peptide blocker of AP-2-Slack binding, we demonstrated that this interaction is essential for clathrin recruitment to the DRG membrane, Slack channel endocytosis, and DRG neuronal hyperexcitability after PKA activation. Together, these findings uncover AP-2 and clathrin as players in Slack channel regulation. Given the significant role of Slack in nociceptive neuronal excitability, the AP-2 clathrin-mediated endocytosis trafficking mechanism may enable targeting of peripheral and possibly, central neuronal sensitization. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  10. Glutamate neurons are intermixed with midbrain dopamine neurons in nonhuman primates and humans

    PubMed Central

    Root, David H.; Wang, Hui-Ling; Liu, Bing; Barker, David J.; Mód, László; Szocsics, Péter; Silva, Afonso C.; Maglóczky, Zsófia; Morales, Marisela

    2016-01-01

    The rodent ventral tegmental area (VTA) and substantia nigra pars compacta (SNC) contain dopamine neurons intermixed with glutamate neurons (expressing vesicular glutamate transporter 2; VGluT2), which play roles in reward and aversion. However, identifying the neuronal compositions of the VTA and SNC in higher mammals has remained challenging. Here, we revealed VGluT2 neurons within the VTA and SNC of nonhuman primates and humans by simultaneous detection of VGluT2 mRNA and tyrosine hydroxylase (TH; for identification of dopamine neurons). We found that several VTA subdivisions share similar cellular compositions in nonhuman primates and humans; their rostral linear nuclei have a high prevalence of VGluT2 neurons lacking TH; their paranigral and parabrachial pigmented nuclei have mostly TH neurons, and their parabrachial pigmented nuclei have dual VGluT2-TH neurons. Within nonhuman primates and humans SNC, the vast majority of neurons are TH neurons but VGluT2 neurons were detected in the pars lateralis subdivision. The demonstration that midbrain dopamine neurons are intermixed with glutamate or glutamate-dopamine neurons from rodents to humans offers new opportunities for translational studies towards analyzing the roles that each of these neurons play in human behavior and in midbrain-associated illnesses such as addiction, depression, schizophrenia, and Parkinson’s disease. PMID:27477243

  11. Endocytosis contributes to BMP2-induced Smad signalling and neuronal growth.

    PubMed

    Hegarty, Shane V; Sullivan, Aideen M; O'Keeffe, Gerard W

    2017-03-16

    Bone morphogenetic protein 2 (BMP2) is a neurotrophic factor which induces the growth of midbrain dopaminergic (DA) neurons in vitro and in vivo, and its neurotrophic effects have been shown to be dependent on activation of BMP receptors (BMPRs) and Smad 1/5/8 signalling. However, the precise intracellular cascades that regulate BMP2-BMPR-Smad-signalling-induced neurite growth remain unknown. Endocytosis has been shown to regulate Smad 1/5/8 signalling and differentiation induced by BMPs. However, these studies were carried out in non-neural cells. Indeed, there are scant reports regarding the role of endocytosis in BMP-Smad signalling in neurons. To address this, and to further characterise the mechanisms regulating the neurotrophic effects of BMP2, the present study examined the role of dynamin-dependent endocytosis in BMP2-induced Smad signalling and neurite growth in the SH-SY5Y neuronal cell line. The activation, temporal kinetics and magnitude of Smad 1/5/8 signalling induced by BMP2 were significantly attenuated by dynasore-mediated inhibition of endocytosis in SH-SY5Y cells. Furthermore, BMP2-induced increases in neurite length and neurite branching in SH-SY5Y cells were significantly reduced following inhibition of dynamin-dependent endocytosis using dynasore. This study demonstrates that BMP2-induced Smad signalling and neurite growth is regulated by dynamin-dependent endocytosis in a model of human midbrain dopaminergic neurons. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Neurochemical excitation of propriospinal neurons facilitates locomotor command signal transmission in the lesioned spinal cord.

    PubMed

    Zaporozhets, Eugene; Cowley, Kristine C; Schmidt, Brian J

    2011-06-01

    Previous studies of the in vitro neonatal rat brain stem-spinal cord showed that propriospinal relays contribute to descending transmission of a supraspinal command signal that is capable of activating locomotion. Using the same preparation, the present series examines whether enhanced excitation of thoracic propriospinal neurons facilitates propagation of the locomotor command signal in the lesioned spinal cord. First, we identified neurotransmitters contributing to normal endogenous propriospinal transmission of the locomotor command signal by testing the effect of receptor antagonists applied to cervicothoracic segments during brain stem-induced locomotor-like activity. Spinal cords were either intact or contained staggered bilateral hemisections located at right T1/T2 and left T10/T11 junctions designed to abolish direct long-projecting bulbospinal axons. Serotonergic, noradrenergic, dopaminergic, and glutamatergic, but not cholinergic, receptor antagonists blocked locomotor-like activity. Approximately 73% of preparations with staggered bilateral hemisections failed to generate locomotor-like activity in response to electrical stimulation of the brain stem alone; such preparations were used to test the effect of neuroactive substances applied to thoracic segments (bath barriers placed at T3 and T9) during brain stem stimulation. The percentage of preparations developing locomotor-like activity was as follows: 5-HT (43%), 5-HT/N-methyl-D-aspartate (NMDA; 33%), quipazine (42%), 8-hydroxy-2-(di-n-propylamino)tetralin (20%), methoxamine (45%), and elevated bath K(+) concentration (29%). Combined norepinephrine and dopamine increased the success rate (67%) compared with the use of either agent alone (4 and 7%, respectively). NMDA, Mg(2+) ion removal, clonidine, and acetylcholine were ineffective. The results provide proof of principle that artificial excitation of thoracic propriospinal neurons can improve supraspinal control over hindlimb locomotor networks in the

  13. A chimeric path to neuronal synchronization

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Essaki Arumugam, Easwara Moorthy; Spano, Mark L.

    2015-01-15

    Synchronization of neuronal activity is associated with neurological disorders such as epilepsy. This process of neuronal synchronization is not fully understood. To further our understanding, we have experimentally studied the progression of this synchronization from normal neuronal firing to full synchronization. We implemented nine FitzHugh-Nagumo neurons (a simplified Hodgkin-Huxley model) via discrete electronics. For different coupling parameters (synaptic strengths), the neurons in the ring were either unsynchronized or completely synchronized when locally coupled in a ring. When a single long-range connection (nonlocal coupling) was introduced, an intermediate state known as a chimera appeared. The results indicate that (1) epilepsy ismore » likely not only a dynamical disease but also a topological disease, strongly tied to the connectivity of the underlying network of neurons, and (2) the synchronization process in epilepsy may not be an “all or none” phenomenon, but can pass through an intermediate stage (chimera)« less

  14. Electrical remodelling maintains firing properties in cortical pyramidal neurons lacking KCND2-encoded A-type K+ currents.

    PubMed

    Nerbonne, Jeanne M; Gerber, Benjamin R; Norris, Aaron; Burkhalter, Andreas

    2008-03-15

    Considerable experimental evidence has accumulated demonstrating a role for voltage-gated K(+) (Kv) channel pore-forming (alpha) subunits of the Kv4 subfamily in the generation of fast transient outward K(+), I(A), channels. Immunohistochemical data suggest that I(A) channels in hippocampal and cortical pyramidal neurons reflect the expression of homomeric Kv4.2 channels. The experiments here were designed to define directly the role of Kv4.2 in the generation of I(A) in cortical pyramidal neurons and to determine the functional consequences of the targeted deletion of Kv4.2 on the resting and active membrane properties of these cells. Whole-cell voltage-clamp recordings, obtained from visual cortical pyramidal neurons isolated from mice in which the KCND2 (Kv4.2) locus was disrupted (Kv4.2-/- mice), revealed that I(A) is indeed eliminated. In addition, the densities of other Kv current components, specifically I(K) and I(ss), are increased significantly (P < 0.001) in most ( approximately 80%) Kv4.2-/- cells. The deletion of KCND2 (Kv4.2) and the elimination of I(A) is also accompanied by the loss of the Kv4 channel accessory protein KChIP3, suggesting that in the absence of Kv4.2, the KChIP3 protein is targeted for degradation. The expression levels of several Kv alpha subunits (Kv4.3, Kv1.4, Kv2.1, Kv2.2), however, are not measurably altered in Kv4.2-/- cortices. Although I(A) is eliminated in Kv4.2-/- pyramidal neurons, the mean +/- s.e.m. current threshold for action potential generation and the waveforms of action potentials are indistinguishable from those recorded from wild-type cells. Repetitive firing is also maintained in Kv4.2-/- cortical pyramidal neurons, suggesting that the increased densities of I(K) and I(ss) compensate for the in vivo loss of I(A).

  15. Chronic hypoxia suppresses the CO2 response of solitary complex (SC) neurons from rats.

    PubMed

    Nichols, Nicole L; Wilkinson, Katherine A; Powell, Frank L; Dean, Jay B; Putnam, Robert W

    2009-09-30

    We studied the effect of chronic hypobaric hypoxia (CHx; 10-11% O(2)) on the response to hypercapnia (15% CO(2)) of individual solitary complex (SC) neurons from adult rats. We simultaneously measured the intracellular pH and firing rate responses to hypercapnia of SC neurons in superfused medullary slices from control and CHx-adapted adult rats using the blind whole cell patch clamp technique and fluorescence imaging microscopy. We found that CHx caused the percentage of SC neurons inhibited by hypercapnia to significantly increase from about 10% up to about 30%, but did not significantly alter the percentage of SC neurons activated by hypercapnia (50% in control vs. 35% in CHx). Further, the magnitudes of the responses of SC neurons from control rats (chemosensitivity index for activated neurons of 166+/-11% and for inhibited neurons of 45+/-15%) were the same in SC neurons from CHx-adapted rats. This plasticity induced in chemosensitive SC neurons by CHx appears to involve intrinsic changes in neuronal properties since they were the same in synaptic blockade medium.

  16. Shp2 in Forebrain Neurons Regulates Synaptic Plasticity, Locomotion, and Memory Formation in Mice

    PubMed Central

    Kusakari, Shinya; Saitow, Fumihito; Ago, Yukio; Shibasaki, Koji; Sato-Hashimoto, Miho; Matsuzaki, Yasunori; Kotani, Takenori; Murata, Yoji; Hirai, Hirokazu; Matsuda, Toshio; Suzuki, Hidenori

    2015-01-01

    Shp2 (Src homology 2 domain-containing protein tyrosine phosphatase 2) regulates neural cell differentiation. It is also expressed in postmitotic neurons, however, and mutations of Shp2 are associated with clinical syndromes characterized by mental retardation. Here we show that conditional-knockout (cKO) mice lacking Shp2 specifically in postmitotic forebrain neurons manifest abnormal behavior, including hyperactivity. Novelty-induced expression of immediate-early genes and activation of extracellular-signal-regulated kinase (Erk) were attenuated in the cerebral cortex and hippocampus of Shp2 cKO mice, suggestive of reduced neuronal activity. In contrast, ablation of Shp2 enhanced high-K+-induced Erk activation in both cultured cortical neurons and synaptosomes, whereas it inhibited that induced by brain-derived growth factor in cultured neurons. Posttetanic potentiation and paired-pulse facilitation were attenuated and enhanced, respectively, in hippocampal slices from Shp2 cKO mice. The mutant mice also manifested transient impairment of memory formation in the Morris water maze. Our data suggest that Shp2 contributes to regulation of Erk activation and synaptic plasticity in postmitotic forebrain neurons and thereby controls locomotor activity and memory formation. PMID:25713104

  17. ERK1/2 mediates glucose-regulated POMC gene expression in hypothalamic neurons.

    PubMed

    Zhang, Juan; Zhou, Yunting; Chen, Cheng; Yu, Feiyuan; Wang, Yun; Gu, Jiang; Ma, Lian; Ho, Guyu

    2015-04-01

    Hypothalamic glucose-sensing neurons regulate the expression of genes encoding feeding-related neuropetides POMC, AgRP, and NPY - the key components governing metabolic homeostasis. AMP-activated protein kinase (AMPK) is postulated to be the molecular mediator relaying glucose signals to regulate the expression of these neuropeptides. Whether other signaling mediator(s) plays a role is not clear. In this study, we investigated the role of ERK1/2 using primary hypothalamic neurons as the model system. The primary neurons were differentiated from hypothalamic progenitor cells. The differentiated neurons possessed the characteristic neuronal cell morphology and expressed neuronal post-mitotic markers as well as leptin-regulated orexigenic POMC and anorexigenic AgRP/NPY genes. Treatment of cells with glucose dose-dependently increased POMC and decreased AgRP/NPY expression with a concurrent suppression of AMPK phosphorylation. In addition, glucose treatment dose-dependently increased the ERK1/2 phosphorylation. Blockade of ERK1/2 activity with its specific inhibitor PD98059 partially (approximately 50%) abolished glucose-induced POMC expression, but had little effect on AgRP/NPY expression. Conversely, blockade of AMPK activity with its specific inhibitor produced a partial (approximately 50%) reversion of low-glucose-suppressed POMC expression, but almost completely blunted the low-glucose-induced AgRP/NPY expression. The results indicate that ERK1/2 mediated POMC but not AgRP/NPY expression. Confirming the in vitro findings, i.c.v. administration of PD98059 in rats similarly attenuated glucose-induced POMC expression in the hypothalamus, but again had little effect on AgRP/NPY expression. The results are indicative of a novel role of ERK1/2 in glucose-regulated POMC expression and offer new mechanistic insights into hypothalamic glucose sensing. © 2015 Society for Endocrinology.

  18. Group IIA secretory phospholipase A2 (GIIA) mediates apoptotic death during NMDA receptor activation in rat primary cortical neurons.

    PubMed

    Chiricozzi, Elena; Fernandez-Fernandez, Seila; Nardicchi, Vincenza; Almeida, Angeles; Bolaños, Juan Pedro; Goracci, Gianfrancesco

    2010-03-01

    Phospholipases A(2) (PLA(2)) participate in neuronal death signalling pathways because of their ability to release lipid mediators, although the contribution of each isoform and mechanism of neurotoxicity are still elusive. Using a novel fluorogenic method to assess changes in a PLA(2) activity by flow cytometry, here we show that the group IIA secretory phospholipase A(2) isoform (GIIA) was specifically activated in cortical neurons following stimulation of N-methyl-d-aspartate glutamate receptor subtype (NMDAR). For activation, GIIA required Ca(2+) and reactive oxygen/nitrogen species, and inhibition of its activity fully prevented NMDAR-mediated neuronal apoptotic death. Superoxide, nitric oxide or peroxynitrite donors stimulated GIIA activity, which mediated neuronal death. Intriguingly, we also found that GIIA activity induced mitochondrial superoxide production after NMDAR stimulation. These results reveal a novel role for GIIA in excitotoxicity both as target and producer of superoxide in a positive-loop of activation that may contribute to the propagation of neurodegeneration.

  19. Contribution of synchronized GABAergic neurons to dopaminergic neuron firing and bursting

    PubMed Central

    Myroshnychenko, Maxym; Zakharov, Denis; di Volo, Matteo; Gutkin, Boris; Lapish, Christopher C.; Kuznetsov, Alexey

    2016-01-01

    In the ventral tegmental area (VTA), interactions between dopamine (DA) and γ-aminobutyric acid (GABA) neurons are critical for regulating DA neuron activity and thus DA efflux. To provide a mechanistic explanation of how GABA neurons influence DA neuron firing, we developed a circuit model of the VTA. The model is based on feed-forward inhibition and recreates canonical features of the VTA neurons. Simulations revealed that γ-aminobutyric acid (GABA) receptor (GABAR) stimulation can differentially influence the firing pattern of the DA neuron, depending on the level of synchronization among GABA neurons. Asynchronous activity of GABA neurons provides a constant level of inhibition to the DA neuron and, when removed, produces a classical disinhibition burst. In contrast, when GABA neurons are synchronized by common synaptic input, their influence evokes additional spikes in the DA neuron, resulting in increased measures of firing and bursting. Distinct from previous mechanisms, the increases were not based on lowered firing rate of the GABA neurons or weaker hyperpolarization by the GABAR synaptic current. This phenomenon was induced by GABA-mediated hyperpolarization of the DA neuron that leads to decreases in intracellular calcium (Ca2+) concentration, thus reducing the Ca2+-dependent potassium (K+) current. In this way, the GABA-mediated hyperpolarization replaces Ca2+-dependent K+ current; however, this inhibition is pulsatile, which allows the DA neuron to fire during the rhythmic pauses in inhibition. Our results emphasize the importance of inhibition in the VTA, which has been discussed in many studies, and suggest a novel mechanism whereby computations can occur locally. PMID:27440240

  20. Expression of the P2X2 receptor in different classes of ileum myenteric neurons in the female obese ob/ob mouse

    PubMed Central

    Mizuno, Márcia Sanae; Crisma, Amanda Rabello; Borelli, Primavera; Castelucci, Patricia

    2012-01-01

    AIM: To examine whether the ob/ob mouse model of obesity is accompanied by enteric nervous system abnormalities such as altered motility. METHODS: The study examined the distribution of the P2X2 receptor (P2X2R) in myenteric neurons of female ob/ob mice. Specifically, we used immunohistochemistry to analyze the co-expression of the P2X2R with neuronal nitric oxide synthase (nNOS), choline acetyltransferase (ChAT), and calretinin (CalR) in neurons of the small intestine myenteric plexus in ob/ob and control female mice. In these sections, we used scanning confocal microscopy to analyze the co-localization of these markers as well as the neuronal density (cm2) and area profile (μm²) of P2X2R-positive neurons. In addition, enteric neurons were labeled using the nicotinamide adenine dinucleotide (NADH) diaphorase method and analyzed with light microscopy as an alternate means by which to analyze neuronal density and area. RESULTS: In the present study, we observed a 29.6% increase in the body weight of the ob/ob animals (OG) compared to the control group (CG). In addition, the average small intestine area was increased by approximately 29.6% in the OG compared to the CG. Immunoreactivity (IR) for the P2X2R, nNOS, ChAT and CalR was detectable in the myenteric plexus, as well as in the smooth muscle, in both groups. This IR appeared to be mainly cytoplasmic and was also associated with the cell membrane of the myenteric plexus neurons, where it outlined the neuronal cell bodies and their processes. P2X2R-IR was observed to co-localize 100% with that for nNOS, ChAT and CalR in neurons of both groups. In the ob/ob group, however, we observed that the neuronal density (neuron/cm2) of P2X2R-IR cells was increased by 62% compared to CG, while that of NOS-IR and ChAT-IR neurons was reduced by 49% and 57%, respectively, compared to control mice. The neuronal density of CalR-IR neurons was not different between the groups. Morphometric studies further demonstrated that the

  1. Quercetin Exerts Differential Neuroprotective Effects Against H2O2 and Aβ Aggregates in Hippocampal Neurons: the Role of Mitochondria.

    PubMed

    Godoy, Juan A; Lindsay, Carolina B; Quintanilla, Rodrigo A; Carvajal, Francisco J; Cerpa, Waldo; Inestrosa, Nibaldo C

    2017-11-01

    Amyloid-β peptide (Aβ) is one of the major players in the pathogenesis of Alzheimer's disease (AD). Despite numerous studies, the mechanisms by which Aβ induces neurodegeneration are not completely understood. Oxidative stress is considered a major contributor to the pathogenesis of AD, and accumulating evidence indicates that high levels of reactive oxygen species (ROS) are involved in Aβ-induced neurodegeneration. Moreover, Aβ can induce the deregulation of calcium homeostasis, which also affects mitochondrial function and triggers neuronal cell death. In the present study, we analyzed the effects of quercetin, a plant flavonoid with antioxidant properties, on oxidative stress- and Aβ-induced degeneration. Our results indicate that quercetin efficiently protected against H 2 O 2 -induced neuronal toxicity; however, this protection was only partial in rat hippocampal neurons that were treated with Aβ. Treatment with quercetin decreased ROS levels, recovered the normal morphology of mitochondria, and prevented mitochondrial dysfunction in neurons that were treated with H 2 O 2 . By contrast, quercetin treatment partially rescued hippocampal neurons from Aβ-induced mitochondrial injury. Most importantly, quercetin treatment prevented the toxic effects that are induced by H 2 O 2 in hippocampal neurons and, to a lesser extent, the Aβ-induced toxicity that is associated with the superoxide anion, which is a precursor of ROS production in mitochondria. Collectively, these results indicate that quercetin exerts differential effects on the prevention of H 2 O 2 - and Aβ-induced neurotoxicity in hippocampal neurons and may be a powerful tool for dissecting the molecular mechanisms underlying Aβ neurotoxicity.

  2. A novel O2-sensing mechanism in rat glossopharyngeal neurones mediated by a halothane-inhibitable background K+ conductance.

    PubMed

    Campanucci, Verónica A; Fearon, Ian M; Nurse, Colin A

    2003-05-01

    Modulation of K+ channels by hypoxia is a common O2-sensing mechanism in specialised cells. More recently, acid-sensitive TASK-like background K+ channels, which play a key role in setting the resting membrane potential, have been implicated in O2-sensing in certain cell types. Here, we report a novel O2 sensitivity mediated by a weakly pH-sensitive background K+ conductance in nitric oxide synthase (NOS)-positive neurones of the glossopharyngeal nerve (GPN). This conductance was insensitive to 30 mM TEA, 5 mM 4-aminopyridine (4-AP) and 200 microM Cd2+, but was reversibly inhibited by hypoxia (O2 tension (PO2) = 15 mmHg), 2-5 mM halothane, 10 mM barium and 1 mM quinidine. Notably, the presence of halothane occluded the inhibitory effect of hypoxia. Under current clamp, these agents depolarised GPN neurones. In contrast, arachidonic acid (5-10 microM) caused membrane hyperpolarisation and potentiation of the background K+ current. This pharmacological profile suggests the O2-sensitive conductance in GPN neurones is mediated by a class of background K+ channels different from the TASK family; it appears more closely related to the THIK (tandem pore domain halothane-inhibited K+) subfamily, or may represent a new member of the background K+ family. Since GPN neurones are thought to provide NO-mediated efferent inhibition of the carotid body (CB), these channels may contribute to the regulation of breathing during hypoxia via negative feedback control of CB function, as well as to the inhibitory effect of volatile anaesthetics (e.g. halothane) on respiration.

  3. Thy1.2 YFP-16 Transgenic Mouse Labels a Subset of Large-Diameter Sensory Neurons that Lack TRPV1 Expression

    PubMed Central

    Taylor-Clark, Thomas E.; Wu, Kevin Y.; Thompson, Julie-Ann; Yang, Kiseok; Bahia, Parmvir K.; Ajmo, Joanne M.

    2015-01-01

    The Thy1.2 YFP-16 mouse expresses yellow fluorescent protein (YFP) in specific subsets of peripheral and central neurons. The original characterization of this model suggested that YFP was expressed in all sensory neurons, and this model has been subsequently used to study sensory nerve structure and function. Here, we have characterized the expression of YFP in the sensory ganglia (DRG, trigeminal and vagal) of the Thy1.2 YFP-16 mouse, using biochemical, functional and anatomical analyses. Despite previous reports, we found that YFP was only expressed in approximately half of DRG and trigeminal neurons and less than 10% of vagal neurons. YFP-expression was only found in medium and large-diameter neurons that expressed neurofilament but not TRPV1. YFP-expressing neurons failed to respond to selective agonists for TRPV1, P2X2/3 and TRPM8 channels in Ca2+ imaging assays. Confocal analysis of glabrous skin, hairy skin of the back and ear and skeletal muscle indicated that YFP was expressed in some peripheral terminals with structures consistent with their presumed non-nociceptive nature. In summary, the Thy1.2 YFP-16 mouse expresses robust YFP expression in only a subset of sensory neurons. But this mouse model is not suitable for the study of nociceptive nerves or the function of such nerves in pain and neuropathies. PMID:25746468

  4. Coordinated temporal and spatial control of motor neuron and serotonergic neuron generation from a common pool of CNS progenitors.

    PubMed

    Pattyn, Alexandre; Vallstedt, Anna; Dias, José M; Samad, Omar Abdel; Krumlauf, Robb; Rijli, Filippo M; Brunet, Jean-Francois; Ericson, Johan

    2003-03-15

    Neural progenitor cells often produce distinct types of neurons in a specific order, but the determinants that control the sequential generation of distinct neuronal subclasses in the vertebrate CNS remain poorly defined. We examined the sequential generation of visceral motor neurons and serotonergic neurons from a common pool of neural progenitors located in the ventral hindbrain. We found that the temporal specification of these neurons varies along the anterior-posterior axis of the hindbrain, and that the timing of their generation critically depends on the integrated activities of Nkx- and Hox-class homeodomain proteins. A primary function of these proteins is to coordinate the spatial and temporal activation of the homeodomain protein Phox2b, which in turn acts as a binary switch in the selection of motor neuron or serotonergic neuronal fate. These findings assign new roles for Nkx, Hox, and Phox2 proteins in the control of temporal neuronal fate determination, and link spatial and temporal patterning of CNS neuronal fates.

  5. Coordinated temporal and spatial control of motor neuron and serotonergic neuron generation from a common pool of CNS progenitors

    PubMed Central

    Pattyn, Alexandre; Vallstedt, Anna; Dias, José M.; Samad, Omar Abdel; Krumlauf, Robb; Rijli, Filippo M.; Brunet, Jean-Francois; Ericson, Johan

    2003-01-01

    Neural progenitor cells often produce distinct types of neurons in a specific order, but the determinants that control the sequential generation of distinct neuronal subclasses in the vertebrate CNS remain poorly defined. We examined the sequential generation of visceral motor neurons and serotonergic neurons from a common pool of neural progenitors located in the ventral hindbrain. We found that the temporal specification of these neurons varies along the anterior-posterior axis of the hindbrain, and that the timing of their generation critically depends on the integrated activities of Nkx- and Hox-class homeodomain proteins. A primary function of these proteins is to coordinate the spatial and temporal activation of the homeodomain protein Phox2b, which in turn acts as a binary switch in the selection of motor neuron or serotonergic neuronal fate. These findings assign new roles for Nkx, Hox, and Phox2 proteins in the control of temporal neuronal fate determination, and link spatial and temporal patterning of CNS neuronal fates. PMID:12651891

  6. The activity-dependent histone variant H2BE modulates the life span of olfactory neurons

    PubMed Central

    Santoro, Stephen W; Dulac, Catherine

    2012-01-01

    We have identified a replication-independent histone variant, Hist2h2be (referred to herein as H2be), which is expressed exclusively by olfactory chemosensory neurons. Levels of H2BE are heterogeneous among olfactory neurons, but stereotyped according to the identity of the co-expressed olfactory receptor (OR). Gain- and loss-of-function experiments demonstrate that changes in H2be expression affect olfactory function and OR representation in the adult olfactory epithelium. We show that H2BE expression is reduced by sensory activity and that it promotes neuronal cell death, such that inactive olfactory neurons display higher levels of the variant and shorter life spans. Post-translational modifications (PTMs) of H2BE differ from those of the canonical H2B, consistent with a role for H2BE in altering transcription. We propose a physiological function for H2be in modulating olfactory neuron population dynamics to adapt the OR repertoire to the environment. DOI: http://dx.doi.org/10.7554/eLife.00070.001 PMID:23240083

  7. A neuron-astrocyte transistor-like model for neuromorphic dressed neurons.

    PubMed

    Valenza, G; Pioggia, G; Armato, A; Ferro, M; Scilingo, E P; De Rossi, D

    2011-09-01

    Experimental evidences on the role of the synaptic glia as an active partner together with the bold synapse in neuronal signaling and dynamics of neural tissue strongly suggest to investigate on a more realistic neuron-glia model for better understanding human brain processing. Among the glial cells, the astrocytes play a crucial role in the tripartite synapsis, i.e. the dressed neuron. A well-known two-way astrocyte-neuron interaction can be found in the literature, completely revising the purely supportive role for the glia. The aim of this study is to provide a computationally efficient model for neuron-glia interaction. The neuron-glia interactions were simulated by implementing the Li-Rinzel model for an astrocyte and the Izhikevich model for a neuron. Assuming the dressed neuron dynamics similar to the nonlinear input-output characteristics of a bipolar junction transistor, we derived our computationally efficient model. This model may represent the fundamental computational unit for the development of real-time artificial neuron-glia networks opening new perspectives in pattern recognition systems and in brain neurophysiology. Copyright © 2011 Elsevier Ltd. All rights reserved.

  8. Zebrafish CiA interneurons are late-born primary neurons.

    PubMed

    Yeo, Sang-Yeob

    2009-12-11

    Pax2 is a neural-related transcription factor downstream of Notch signaling and is expressed in the developing spinal cord of zebrafish, including in CiA interneurons. However, the characteristics of pax2-positive neurons are largely unknown. The goal of this study was to characterize Pax2-positive neurons by examining their expression in embryos in which Notch function had been knocked down by mutation or injection of a morpholino or mRNA. I found that Pax2-positive CiA interneurons were late-differentiating primary neurons. pax2.1 was expressed in CoPA commissural neurons and CiA interneurons at 26 hpf. The number of pax2.1-positive cells increased in mind bomb mutant embryos or embryos injected with Su(H)1-MO, but not in cells injected with Xenopus Delta or Delta(stu) mRNA. These observations imply that Notch signaling plays a role in regulating the number of CiA neurons by preventing uncommitted precursors from acquiring a neuronal fate during vertebrate development.

  9. Delayed rectifier potassium channels are involved in SO2 derivative-induced hippocampal neuronal injury.

    PubMed

    Li, Guangke; Sang, Nan

    2009-01-01

    Recent studies implicate the possible neurotoxicity of SO(2), however, its mechanisms remain unclear. In the present study, we investigated SO(2) derivative-induced effect on delayed rectifier potassium channels (I(K)) and cellular death/apoptosis in primary cultured hippocampal neurons. The results demonstrate that SO(2) derivatives (NaHSO(3) and Na(2)SO(3), 3:1M/M) effectively augmented I(K) and promoted the activation of delayed rectifier potassium channels. Also, SO(2) derivatives increased neuronal death percentage and contributed to the formation of DNA ladder in concentration-dependent manners. Interestingly, the neuronal death and DNA ladder formation, caused by SO(2) derivatives, could be attenuated by the delayed rectifier potassium channel blocker (tetraethylammonium, TEA), but not by the transient outward potassium channel blocker (4-aminopyridine, 4-AP). It implies that stimulating delayed rectifier potassium channels were involved in SO(2) derivative-caused hippocampal neuronal insults, and blocking these channels might be one of the possibly clinical treatment for SO(2)-caused neuronal dysfunction.

  10. Cav1.3 channels control D2-autoreceptor responses via NCS-1 in substantia nigra dopamine neurons

    PubMed Central

    Dragicevic, Elena; Poetschke, Christina; Duda, Johanna; Schlaudraff, Falk; Lammel, Stephan; Schiemann, Julia; Fauler, Michael; Hetzel, Andrea; Watanabe, Masahiko; Lujan, Rafael; Malenka, Robert C.; Striessnig, Joerg

    2014-01-01

    Dopamine midbrain neurons within the substantia nigra are particularly prone to degeneration in Parkinson’s disease. Their selective loss causes the major motor symptoms of Parkinson’s disease, but the causes for the high vulnerability of SN DA neurons, compared to neighbouring, more resistant ventral tegmental area dopamine neurons, are still unclear. Consequently, there is still no cure available for Parkinson’s disease. Current therapies compensate the progressive loss of dopamine by administering its precursor l-DOPA and/or dopamine D2-receptor agonists. D2-autoreceptors and Cav1.3-containing L-type Ca2+ channels both contribute to Parkinson’s disease pathology. L-type Ca2+ channel blockers protect SN DA neurons from degeneration in Parkinson’s disease and its mouse models, and they are in clinical trials for neuroprotective Parkinson’s disease therapy. However, their physiological functions in SN DA neurons remain unclear. D2-autoreceptors tune firing rates and dopamine release of SN DA neurons in a negative feedback loop through activation of G-protein coupled potassium channels (GIRK2, or KCNJ6). Mature SN DA neurons display prominent, non-desensitizing somatodendritic D2-autoreceptor responses that show pronounced desensitization in PARK-gene Parkinson’s disease mouse models. We analysed surviving human SN DA neurons from patients with Parkinson’s disease and from controls, and detected elevated messenger RNA levels of D2-autoreceptors and GIRK2 in Parkinson’s disease. By electrophysiological analysis of postnatal juvenile and adult mouse SN DA neurons in in vitro brain-slices, we observed that D2-autoreceptor desensitization is reduced with postnatal maturation. Furthermore, a transient high-dopamine state in vivo, caused by one injection of either l-DOPA or cocaine, induced adult-like, non-desensitizing D2-autoreceptor responses, selectively in juvenile SN DA neurons, but not ventral tegmental area dopamine neurons. With pharmacological

  11. Cav1.3 channels control D2-autoreceptor responses via NCS-1 in substantia nigra dopamine neurons.

    PubMed

    Dragicevic, Elena; Poetschke, Christina; Duda, Johanna; Schlaudraff, Falk; Lammel, Stephan; Schiemann, Julia; Fauler, Michael; Hetzel, Andrea; Watanabe, Masahiko; Lujan, Rafael; Malenka, Robert C; Striessnig, Joerg; Liss, Birgit

    2014-08-01

    Dopamine midbrain neurons within the substantia nigra are particularly prone to degeneration in Parkinson's disease. Their selective loss causes the major motor symptoms of Parkinson's disease, but the causes for the high vulnerability of SN DA neurons, compared to neighbouring, more resistant ventral tegmental area dopamine neurons, are still unclear. Consequently, there is still no cure available for Parkinson's disease. Current therapies compensate the progressive loss of dopamine by administering its precursor l-DOPA and/or dopamine D2-receptor agonists. D2-autoreceptors and Cav1.3-containing L-type Ca(2+) channels both contribute to Parkinson's disease pathology. L-type Ca(2+) channel blockers protect SN DA neurons from degeneration in Parkinson's disease and its mouse models, and they are in clinical trials for neuroprotective Parkinson's disease therapy. However, their physiological functions in SN DA neurons remain unclear. D2-autoreceptors tune firing rates and dopamine release of SN DA neurons in a negative feedback loop through activation of G-protein coupled potassium channels (GIRK2, or KCNJ6). Mature SN DA neurons display prominent, non-desensitizing somatodendritic D2-autoreceptor responses that show pronounced desensitization in PARK-gene Parkinson's disease mouse models. We analysed surviving human SN DA neurons from patients with Parkinson's disease and from controls, and detected elevated messenger RNA levels of D2-autoreceptors and GIRK2 in Parkinson's disease. By electrophysiological analysis of postnatal juvenile and adult mouse SN DA neurons in in vitro brain-slices, we observed that D2-autoreceptor desensitization is reduced with postnatal maturation. Furthermore, a transient high-dopamine state in vivo, caused by one injection of either l-DOPA or cocaine, induced adult-like, non-desensitizing D2-autoreceptor responses, selectively in juvenile SN DA neurons, but not ventral tegmental area dopamine neurons. With pharmacological and genetic

  12. Glucose and insulin induce Ca2+ signaling in nesfatin-1 neurons in the hypothalamic paraventricular nucleus.

    PubMed

    Gantulga, Darambazar; Maejima, Yuko; Nakata, Masanori; Yada, Toshihiko

    2012-04-20

    Nucleobindin-2 derived nesfatin-1 in the hypothalamic paraventricular nucleus (PVN) plays a role in inhibition of feeding. The neural pathways downstream of PVN nesfatin-1 have been extensively investigated. However, regulation of the PVN nesfatin-1 neurons remains unclear. Since starvation decreases and refeeding stimulates nesfatin-1 expression specifically in the PVN, this study aimed to clarify direct effects of meal-evoked metabolic factors, glucose and insulin, on PVN nesfatin-1 neurons. High glucose (10mM) and insulin (10(-13)M) increased cytosolic calcium concentration ([Ca(2+)](i)) in 55 of 331 (16.6%) and 32 of 249 (12.9%) PVN neurons, respectively. Post [Ca(2+)](i) measurement immunocytochemistry identified that 58.2% of glucose-responsive and 62.5% of insulin-responsive neurons were immunoreactive to nesfatin-1. Furthermore, a fraction of the glucose-responsive nesfatin-1 neurons also responded to insulin, and vice versa. Some of the neurons that responded to neither glucose nor insulin were recruited to [Ca(2+)](i) increases by glucose and insulin in combination. Our data demonstrate that glucose and insulin directly interact with and increase [Ca(2+)](i) in nesfatin-1 neurons in the PVN, and that the nesfatin-1 neuron is the primary target for them in the PVN. The results suggest that high glucose- and insulin-induced activation of PVN nesfatin-1 neurons serves as a mechanism through which meal ingestion stimulates nesfatin-1 neurons in the PVN and thereby produces satiety. Copyright © 2012 Elsevier Inc. All rights reserved.

  13. Cyanidin-3-glucoside inhibits glutamate-induced Zn2+ signaling and neuronal cell death in cultured rat hippocampal neurons by inhibiting Ca2+-induced mitochondrial depolarization and formation of reactive oxygen species.

    PubMed

    Yang, Ji Seon; Perveen, Shazia; Ha, Tae Joung; Kim, Seong Yun; Yoon, Shin Hee

    2015-05-05

    Cyanidin-3-glucoside (C3G), a member of the anthocyanin family, is a potent natural antioxidant. However, effects of C3G on glutamate-induced [Zn(2+)]i increase and neuronal cell death remain unknown. We studied the effects of C3G on glutamate-induced [Zn(2+)]i increase and cell death in cultured rat hippocampal neurons from embryonic day 17 maternal Sprague-Dawley rats using digital imaging methods for Zn(2+), Ca(2+), reactive oxygen species (ROS), mitochondrial membrane potential and a MTT assay for cell survival. Treatment with glutamate (100 µM) for 7 min induces reproducible [Zn(2+)]i increase at 35 min interval in cultured rat hippocampal neurons. The intracellular Zn(2+)-chelator TPEN markedly blocked glutamate-induced [Zn(2+)]i increase, but the extracellular Zn(2+) chelator CaEDTA did not affect glutamate-induced [Zn(2+)]i increase. C3G inhibited the glutamate-induced [Zn(2+)]i response in a concentration-dependent manner (IC50 of 14.1 ± 1.1 µg/ml). C3G also significantly inhibited glutamate-induced [Ca(2+)]i increase. Two antioxidants such as Trolox and DTT significantly inhibited the glutamate-induced [Zn(2+)]i response, but they did not affect the [Ca(2+)]i responses. C3G blocked glutamate-induced formation of ROS. Trolox and DTT also inhibited the formation of ROS. C3G significantly inhibited glutamate-induced mitochondrial depolarization. However, TPEN, Trolox and DTT did not affect the mitochondrial depolarization. C3G, Trolox and DTT attenuated glutamate-induced neuronal cell death in cultured rat hippocampal neurons, respectively. Taken together, all these results suggest that cyanidin-3-glucoside inhibits glutamate-induced [Zn(2+)]i increase through a release of Zn(2+) from intracellular sources in cultured rat hippocampal neurons by inhibiting Ca(2+)-induced mitochondrial depolarization and formation of ROS, which is involved in neuroprotection against glutamate-induced cell death. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. IMPACT Is a Developmentally Regulated Protein in Neurons That Opposes the Eukaryotic Initiation Factor 2α Kinase GCN2 in the modulation of Neurite Outgrowth*

    PubMed Central

    Roffé, Martín; Hajj, Glaucia N. M.; Azevedo, Hátylas F.; Alves, Viviane S.; Castilho, Beatriz A.

    2013-01-01

    The product of the mouse Imprinted and Ancient gene, IMPACT, is preferentially expressed in neurons. We have previously shown that IMPACT overexpression inhibits the activation of the protein kinase GCN2, which signals amino acid starvation. GCN2 phosphorylates the α-subunit of eukaryotic translation initiation factor 2 (eIF2α), resulting in inhibition of general protein synthesis but increased translation of specific messages, such as ATF4. GCN2 is also involved in the regulation of neuronal functions, controlling synaptic plasticity, memory, and feeding behavior. We show here that IMPACT abundance increases during differentiation of neurons and neuron-like N2a cells, whereas GCN2 displays lowered activation levels. Upon differentiation, IMPACT associates with translating ribosomes, enhances translation initiation, and down-regulates the expression of ATF4. We further show that endogenous IMPACT promotes neurite outgrowth whereas GCN2 is a strong inhibitor of spontaneous neuritogenesis. Together, these results uncover the participation of the GCN2-IMPACT module of translational regulation in a highly controlled step in the development of the nervous system. PMID:23447528

  15. IMPACT is a developmentally regulated protein in neurons that opposes the eukaryotic initiation factor 2α kinase GCN2 in the modulation of neurite outgrowth.

    PubMed

    Roffé, Martín; Hajj, Glaucia N M; Azevedo, Hátylas F; Alves, Viviane S; Castilho, Beatriz A

    2013-04-12

    The product of the mouse Imprinted and Ancient gene, IMPACT, is preferentially expressed in neurons. We have previously shown that IMPACT overexpression inhibits the activation of the protein kinase GCN2, which signals amino acid starvation. GCN2 phosphorylates the α-subunit of eukaryotic translation initiation factor 2 (eIF2α), resulting in inhibition of general protein synthesis but increased translation of specific messages, such as ATF4. GCN2 is also involved in the regulation of neuronal functions, controlling synaptic plasticity, memory, and feeding behavior. We show here that IMPACT abundance increases during differentiation of neurons and neuron-like N2a cells, whereas GCN2 displays lowered activation levels. Upon differentiation, IMPACT associates with translating ribosomes, enhances translation initiation, and down-regulates the expression of ATF4. We further show that endogenous IMPACT promotes neurite outgrowth whereas GCN2 is a strong inhibitor of spontaneous neuritogenesis. Together, these results uncover the participation of the GCN2-IMPACT module of translational regulation in a highly controlled step in the development of the nervous system.

  16. CB2 Receptor Agonists Protect Human Dopaminergic Neurons against Damage from HIV-1 gp120

    PubMed Central

    Hu, Shuxian; Sheng, Wen S.; Rock, R. Bryan

    2013-01-01

    Despite the therapeutic impact of anti-retroviral therapy, HIV-1-associated neurocognitive disorder (HAND) remains a serious threat to AIDS patients, and there currently remains no specific therapy for the neurological manifestations of HIV-1. Recent work suggests that the nigrostriatal dopaminergic area is a critical brain region for the neuronal dysfunction and death seen in HAND and that human dopaminergic neurons have a particular sensitivity to gp120-induced damage, manifested as reduced function (decreased dopamine uptake), morphological changes, and reduced viability. Synthetic cannabinoids inhibit HIV-1 expression in human microglia, suppress production of inflammatory mediators in human astrocytes, and there is substantial literature demonstrating the neuroprotective properties of cannabinoids in other neuropathogenic processes. Based on these data, experiments were designed to test the hypothesis that synthetic cannabinoids will protect dopaminergic neurons against the toxic effects of the HIV-1 protein gp120. Using a human mesencephalic neuronal/glial culture model, which contains dopaminergic neurons, microglia, and astrocytes, we were able to show that the CB1/CB2 agonist WIN55,212-2 blunts gp120-induced neuronal damage as measured by dopamine transporter function, apoptosis and lipid peroxidation; these actions were mediated principally by the CB2 receptor. Adding supplementary human microglia to our cultures enhances gp120-induced damage; WIN55,212-2 is able to alleviate this enhanced damage. Additionally, WIN55,212-2 inhibits gp120-induced superoxide production by purified human microglial cells, inhibits migration of human microglia towards supernatants generated from gp120-stimulated human mesencephalic neuronal/glial cultures and reduces chemokine and cytokine production from the human mesencephalic neuronal/glial cultures. These data suggest that synthetic cannabinoids are capable of protecting human dopaminergic neurons from gp120 in a variety

  17. Contribution of synchronized GABAergic neurons to dopaminergic neuron firing and bursting.

    PubMed

    Morozova, Ekaterina O; Myroshnychenko, Maxym; Zakharov, Denis; di Volo, Matteo; Gutkin, Boris; Lapish, Christopher C; Kuznetsov, Alexey

    2016-10-01

    In the ventral tegmental area (VTA), interactions between dopamine (DA) and γ-aminobutyric acid (GABA) neurons are critical for regulating DA neuron activity and thus DA efflux. To provide a mechanistic explanation of how GABA neurons influence DA neuron firing, we developed a circuit model of the VTA. The model is based on feed-forward inhibition and recreates canonical features of the VTA neurons. Simulations revealed that γ-aminobutyric acid (GABA) receptor (GABAR) stimulation can differentially influence the firing pattern of the DA neuron, depending on the level of synchronization among GABA neurons. Asynchronous activity of GABA neurons provides a constant level of inhibition to the DA neuron and, when removed, produces a classical disinhibition burst. In contrast, when GABA neurons are synchronized by common synaptic input, their influence evokes additional spikes in the DA neuron, resulting in increased measures of firing and bursting. Distinct from previous mechanisms, the increases were not based on lowered firing rate of the GABA neurons or weaker hyperpolarization by the GABAR synaptic current. This phenomenon was induced by GABA-mediated hyperpolarization of the DA neuron that leads to decreases in intracellular calcium (Ca 2+ ) concentration, thus reducing the Ca 2+ -dependent potassium (K + ) current. In this way, the GABA-mediated hyperpolarization replaces Ca 2+ -dependent K + current; however, this inhibition is pulsatile, which allows the DA neuron to fire during the rhythmic pauses in inhibition. Our results emphasize the importance of inhibition in the VTA, which has been discussed in many studies, and suggest a novel mechanism whereby computations can occur locally. Copyright © 2016 the American Physiological Society.

  18. P21-activated kinase 2 (PAK2) regulates glucose uptake and insulin sensitivity in neuronal cells.

    PubMed

    Varshney, Pallavi; Dey, Chinmoy Sankar

    2016-07-05

    P21-activated kinases (PAKs) are recently reported as important players of insulin signaling and glucose homeostasis in tissues like muscle, pancreas and liver. However, their role in neuronal insulin signaling is still unknown. Present study reports the involvement of PAK2 in neuronal insulin signaling, glucose uptake and insulin resistance. Irrespective of insulin sensitivity, insulin stimulation decreased PAK2 activity. PAK2 downregulation displayed marked enhancement of GLUT4 translocation with increase in glucose uptake whereas PAK2 over-expression showed its reduction. Treatment with Akti-1/2 and wortmannin suggested that Akt and PI3K are mediators of insulin effect on PAK2 and glucose uptake. Rac1 inhibition demonstrated decreased PAK2 activity while inhibition of PP2A resulted in increased PAK2 activity, with corresponding changes in glucose uptake. Taken together, present study demonstrates an inhibitory role of insulin signaling (via PI3K-Akt) and PP2A on PAK2 activity and establishes PAK2 as a Rac1-dependent negative regulator of neuronal glucose uptake and insulin sensitivity. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  19. Neuroprotective and antioxidant activities of bamboo salt soy sauce against H2O2-induced oxidative stress in rat cortical neurons.

    PubMed

    Jeong, Jong Hee; Noh, Min-Young; Choi, Jae-Hyeok; Lee, Haiwon; Kim, Seung Hyun

    2016-04-01

    Bamboo salt (BS) and soy sauce (SS) are traditional foods in Asia, which contain antioxidants that have cytoprotective effects on the body. The majority of SS products contain high levels of common salt, consumption of which has been associated with numerous detrimental effects on the body. However, BS may be considered a healthier substitute to common salt. The present study hypothesized that SS made from BS, known as bamboo salt soy sauce (BSSS), may possess enhanced cytoprotective properties; this was evaluated using a hydrogen peroxide (H 2 O 2 )-induced neuronal cell death rat model. Rat neuronal cells were pretreated with various concentrations (0.001, 0.01, 0.1, 1 and 10%) of BSSS, traditional soy sauce (TRSS) and brewed soy sauce (BRSS), and were subsequently exposed to H 2 O 2 (100 µM). The viability of neuronal cells, and the occurrence of DNA fragmentation, was subsequently examined. Pretreatment of neuronal cells with TRSS and BRSS reduced cell viability in a concentration-dependent manner, whereas neuronal cells pretreated with BSSS exhibited increased cell viability, as compared with non-treated neuronal cells. Furthermore, neuronal cells pretreated with 0.01% BSSS exhibited the greatest increase in viability. Exposure of neuronal cells to H 2 O 2 significantly increased the levels of reactive oxygen species (ROS), B-cell lymphoma 2-associated X protein, poly (ADP-ribose), cleaved poly (ADP-ribose) polymerase, cytochrome c , apoptosis-inducing factor, cleaved caspase-9 and cleaved caspase-3, in all cases. Pretreatment of neuronal cells with BSSS significantly reduced the levels of ROS generated by H 2 O 2 , and increased the levels of phosphorylated AKT and phosphorylated glycogen synthase kinase-3β. Furthermore, the observed effects of BSSS could be blocked by administration of 10 µM LY294002, a phosphatidylinositol 3-kinase inhibitor. The results of the present study suggested that BSSS may exert positive neuroprotective effects against H 2 O 2

  20. Communication between corneal epithelial cells and trigeminal neurons is facilitated by purinergic (P2) and glutamatergic receptors.

    PubMed

    Oswald, Duane J; Lee, Albert; Trinidad, Monique; Chi, Cheryl; Ren, Ruiyi; Rich, Celeste B; Trinkaus-Randall, Vickery

    2012-01-01

    Previously, we demonstrated that nucleotides released upon mechanical injury to corneal epithelium activate purinergic (P2) receptors resulting in mobilization of a Ca(2+) wave. However, the tissue is extensively innervated and communication between epithelium and neurons is critical and not well understood. Therefore, we developed a co-culture of primary trigeminal neurons and human corneal limbal epithelial cells. We demonstrated that trigeminal neurons expressed a repertoire of P2Yand P2X receptor transcripts and responded to P2 agonists in a concentration-dependent manner. Mechanical injuries to epithelia in the co-cultures elicited a Ca(2+) wave that mobilized to neurons and was attenuated by Apyrase, an ectonucleotidase. To elucidate the role of factors released from each cell type, epithelial and neuronal cells were cultured, injured, and the wound media from one cell type was collected and added to the other cell type. Epithelial wound media generated a rapid Ca(2+) mobilization in neuronal cells that was abrogated in the presence of Apyrase, while neuronal wound media elicited a complex response in epithelial cells. The rapid Ca(2+) mobilization was detected, which was abrogated with Apyrase, but it was followed by Ca(2+) waves that occurred in cell clusters. When neuronal wound media was preincubated with a cocktail of N-methyl-D-aspartate (NMDA) receptor inhibitors, the secondary response in epithelia was diminished. Glutamate was detected in the neuronal wound media and epithelial expression of NMDA receptor subunit transcripts was demonstrated. Our results indicate that corneal epithelia and neurons communicate via purinergic and NMDA receptors that mediate the wound response in a highly orchestrated manner.

  1. Cerebellar neuronal loss in amyotrophic lateral sclerosis cases with ATXN2 intermediate repeat expansions.

    PubMed

    Tan, Rachel H; Kril, Jillian J; McGinley, Ciara; Hassani, Mohammad; Masuda-Suzukake, Masami; Hasegawa, Masato; Mito, Remika; Kiernan, Matthew C; Halliday, Glenda M

    2016-02-01

    Despite evidence suggesting that the cerebellum may be targeted in amyotrophic lateral sclerosis (ALS), particularly in cases with repeat expansions in the ATXN2 and C9ORF72 genes, the integrity of cerebellar neurons has yet to be examined. The present study undertakes a histopathological analysis to assess the impact of these repeat expansions on cerebellar neurons and determine whether similar cerebellar pathology occurs in sporadic disease. Purkinje and granule cells were quantified in the vermis and lateral cerebellar hemispheres of ALS cases with repeat expansions in the ATXN2 and C9ORF72 genes, sporadic disease, and sporadic progressive muscular atrophy with only lower motor neuron degeneration. ALS cases with intermediate repeat expansions in the ATXN2 gene demonstrate a significant loss in Purkinje cells in the cerebellar vermis only. Despite ALS cases with expansions in the C9ORF72 gene having the highest burden of inclusion pathology, no neuronal loss was observed in this group. Neuronal numbers were also unchanged in sporadic ALS and sporadic PMA cases. The present study has established a selective loss of Purkinje cells in the cerebellar vermis of ALS cases with intermediate repeat expansions in the ATXN2 gene, suggesting a divergent pathogenic mechanism independent of upper and lower motor neuron degeneration in ALS. We discuss these findings in the context of large repeat expansions in ATXN2 and spinocerebellar ataxia type 2, providing evidence that intermediate repeats in ATXN2 cause significant, albeit less substantial, spinocerebellar damage compared with longer repeats in ATXN2. © 2016 American Neurological Association.

  2. DNA methyltransferase DNMT3a contributes to neuropathic pain by repressing Kcna2 in primary afferent neurons

    PubMed Central

    Zhao, Jian-Yuan; Liang, Lingli; Gu, Xiyao; Li, Zhisong; Wu, Shaogen; Sun, Linlin; Atianjoh, Fidelis E.; Feng, Jian; Mo, Kai; Jia, Shushan; Lutz, Brianna Marie; Bekker, Alex; Nestler, Eric J.; Tao, Yuan-Xiang

    2017-01-01

    Nerve injury induces changes in gene transcription in dorsal root ganglion (DRG) neurons, which may contribute to nerve injury-induced neuropathic pain. DNA methylation represses gene expression. Here, we report that peripheral nerve injury increases expression of the DNA methyltransferase DNMT3a in the injured DRG neurons via the activation of the transcription factor octamer transcription factor 1. Blocking this increase prevents nerve injury-induced methylation of the voltage-dependent potassium (Kv) channel subunit Kcna2 promoter region and rescues Kcna2 expression in the injured DRG and attenuates neuropathic pain. Conversely, in the absence of nerve injury, mimicking this increase reduces the Kcna2 promoter activity, diminishes Kcna2 expression, decreases Kv current, increases excitability in DRG neurons and leads to spinal cord central sensitization and neuropathic pain symptoms. These findings suggest that DNMT3a may contribute to neuropathic pain by repressing Kcna2 expression in the DRG. PMID:28270689

  3. Serotonin 5-HT2C receptor-mediated inhibition of the M-current in hypothalamic POMC neurons.

    PubMed

    Roepke, T A; Smith, A W; Rønnekleiv, O K; Kelly, M J

    2012-06-01

    Hypothalamic proopiomelanocortin (POMC) neurons are controlled by many central signals, including serotonin. Serotonin increases POMC activity and reduces feeding behavior via serotonion [5-hydroxytryptamine (5-HT)] receptors by modulating K(+) currents. A potential K(+) current is the M-current, a noninactivating, subthreshold outward K(+) current. Previously, we found that M-current activity was highly reduced in fasted vs. fed states in neuropeptide Y neurons. Because POMC neurons also respond to energy states, we hypothesized that fasting may alter the M-current and/or its modulation by serotonergic input to POMC neurons. Using visualized-patch recording in neurons from fed male enhanced green fluorescent protein-POMC transgenic mice, we established that POMC neurons expressed a robust M-current (102.1 ± 6.7 pA) that was antagonized by the selective KCNQ channel blocker XE-991 (40 μM). However, the XE-991-sensitive current in POMC neurons did not differ between fed and fasted states. To determine if serotonin suppresses the M-current via the 5-HT(2C) receptor, we examined the effects of the 5-HT(2A)/5-HT(2C) receptor agonist 2,5-dimethoxy-4-iodoamphetamine (DOI) on the M-current. Indeed, DOI attenuated the M-current by 34.5 ± 6.9% and 42.0 ± 5.3% in POMC neurons from fed and fasted male mice, respectively. In addition, the 5-HT(1B)/5-HT(2C) receptor agonist m-chlorophenylpiperazine attenuated the M-current by 42.4 ± 5.4% in POMC neurons from fed male mice. Moreover, the selective 5-HT(2C) receptor antagonist RS-102221 abrogated the actions of DOI in suppressing the M-current. Collectively, these data suggest that although M-current expression does not differ between fed and fasted states in POMC neurons, serotonin inhibits the M-current via activation of 5-HT(2C) receptors to increase POMC neuronal excitability and, subsequently, reduce food intake.

  4. Cell death cascade and molecular therapy in ADAR2-deficient motor neurons of ALS.

    PubMed

    Yamashita, Takenari; Kwak, Shin

    2018-06-23

    TAR DNA-binding protein (TDP-43) pathology in the motor neurons is the most reliable pathological hallmark of amyotrophic lateral sclerosis (ALS), and motor neurons bearing TDP-43 pathology invariably exhibit failure in RNA editing at the GluA2 glutamine/arginine (Q/R) site due to down-regulation of adenosine deaminase acting on RNA 2 (ADAR2). Conditional ADAR2 knockout (AR2) mice display ALS-like phenotype, including progressive motor dysfunction due to loss of motor neurons. Motor neurons devoid of ADAR2 express Q/R site-unedited GluA2, and AMPA receptors with unedited GluA2 in their subunit assembly are abnormally permeable to Ca 2+ , which results in progressive neuronal death. Moreover, analysis of AR2 mice has demonstrated that exaggerated Ca 2+ influx through the abnormal AMPA receptors overactivates calpain, a Ca 2+ -dependent protease, that cleaves TDP-43 into aggregation-prone fragments, which serve as seeds for TDP-43 pathology. Activated calpain also disrupts nucleo-cytoplasmic transport and gene expression by cleaving molecules involved in nucleocytoplasmic transport, including nucleoporins. These lines of evidence prompted us to develop molecular targeting therapy for ALS by normalization of disrupted intracellular environment due to ADAR2 down-regulation. In this review, we have summarized the work from our group on the cell death cascade in sporadic ALS and discussed a potential therapeutic strategy for ALS. Copyright © 2018 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.

  5. Atrophy and neuron loss: effects of a protein-deficient diet on sympathetic neurons.

    PubMed

    Gomes, Silvio Pires; Nyengaard, Jens Randel; Misawa, Rúbia; Girotti, Priscila Azevedo; Castelucci, Patrìcia; Blazquez, Francisco Hernandez Javier; de Melo, Mariana Pereira; Ribeiro, Antonio Augusto Coppi

    2009-12-01

    Protein deficiency is one of the biggest public health problems in the world, accounting for about 30-40% of hospital admissions in developing countries. Nutritional deficiencies lead to alterations in the peripheral nervous system and in the digestive system. Most studies have focused on the effects of protein-deficient diets on the enteric neurons, but not on sympathetic ganglia, which supply extrinsic sympathetic input to the digestive system. Hence, in this study, we investigated whether a protein-restricted diet would affect the quantitative structure of rat coeliac ganglion neurons. Five male Wistar rats (undernourished group) were given a pre- and postnatal hypoproteinic diet receiving 5% casein, whereas the nourished group (n = 5) was fed with 20% casein (normoproteinic diet). Blood tests were carried out on the animals, e.g., glucose, leptin, and triglyceride plasma concentrations. The main structural findings in this study were that a protein-deficient diet (5% casein) caused coeliac ganglion (78%) and coeliac ganglion neurons (24%) to atrophy and led to neuron loss (63%). Therefore, the fall in the total number of coeliac ganglion neurons in protein-restricted rats contrasts strongly with no neuron losses previously described for the enteric neurons of animals subjected to similar protein-restriction diets. Discrepancies between our figures and the data for enteric neurons (using very similar protein-restriction protocols) may be attributable to the counting method used. In light of this, further systematic investigations comparing 2-D and 3-D quantitative methods are warranted to provide even more advanced data on the effects that a protein-deficient diet may exert on sympathetic neurons. (c) 2009 Wiley-Liss, Inc. Copyright 2009 Wiley-Liss, Inc.

  6. Non-cell autonomous influence of MeCP2-deficient glia on neuronal dendritic morphology

    PubMed Central

    Ballas, Nurit; Lioy, Daniel T.; Grunseich, Christopher; Mandel, Gail

    2011-01-01

    The neurodevelopmental disorder Rett Syndrome (RTT) is caused by sporadic mutations in the transcriptional factor methyl-CpG binding protein 2 (MeCP2). Although it is thought that the primary cause of RTT is cell autonomous due to lack of functional MeCP2 in neurons, whether non-cell autonomous factors contribute to the disease, is unknown. Here, we show that loss of MeCP2 occurs not only in neurons but also in glial cells of RTT brain. Using an in vitro co-culture system, we find that mutant astrocytes from a RTT mouse model, and their conditioned medium, fail to support normal dendritic morphology of either wild-type or mutant hippocampal neurons. Our studies suggest that in RTT brain, astrocytes carrying MeCP2 mutations have a non-cell autonomous effect on neuronal properties, likely due to aberrant secretion of soluble factor(s). PMID:19234456

  7. A novel enteric neuron-glia coculture system reveals the role of glia in neuronal development.

    PubMed

    Le Berre-Scoul, Catherine; Chevalier, Julien; Oleynikova, Elena; Cossais, François; Talon, Sophie; Neunlist, Michel; Boudin, Hélène

    2017-01-15

    mediated in part through purinergic P2Y 1 receptor- and glial cell line-derived neurotrophic factor-dependent pathways. Using a novel and valuable culture model to study enteric neuron-glia interactions, our study identified EGCs as a key cellular actor required for neuronal network maturation. © 2016 The Authors. The Journal of Physiology © 2016 The Physiological Society.

  8. Cooperative regulation by G proteins and Na+ of neuronal GIRK2 K+ channels

    PubMed Central

    Wang, Weiwei; Touhara, Kouki K; Weir, Keiko; Bean, Bruce P; MacKinnon, Roderick

    2016-01-01

    G protein gated inward rectifier K+ (GIRK) channels open and thereby silence cellular electrical activity when inhibitory G protein coupled receptors (GPCRs) are stimulated. Here we describe an assay to measure neuronal GIRK2 activity as a function of membrane-anchored G protein concentration. Using this assay we show that four Gβγ subunits bind cooperatively to open GIRK2, and that intracellular Na+ – which enters neurons during action potentials – further amplifies opening mostly by increasing Gβγ affinity. A Na+ amplification function is characterized and used to estimate the concentration of Gβγ subunits that appear in the membrane of mouse dopamine neurons when GABAB receptors are stimulated. We conclude that GIRK2, through its dual responsiveness to Gβγ and Na+, mediates a form of neuronal inhibition that is amplifiable in the setting of excess electrical activity. DOI: http://dx.doi.org/10.7554/eLife.15751.001 PMID:27074662

  9. Receptive-field subfields of V2 neurons in macaque monkeys are adult-like near birth.

    PubMed

    Zhang, Bin; Tao, Xiaofeng; Shen, Guofu; Smith, Earl L; Ohzawa, Izumi; Chino, Yuzo M

    2013-02-06

    Infant primates can discriminate texture-defined form despite their relatively low visual acuity. The neuronal mechanisms underlying this remarkable visual capacity of infants have not been studied in nonhuman primates. Since many V2 neurons in adult monkeys can extract the local features in complex stimuli that are required for form vision, we used two-dimensional dynamic noise stimuli and local spectral reverse correlation to measure whether the spatial map of receptive-field subfields in individual V2 neurons is sufficiently mature near birth to capture local features. As in adults, most V2 neurons in 4-week-old monkeys showed a relatively high degree of homogeneity in the spatial matrix of facilitatory subfields. However, ∼25% of V2 neurons had the subfield map where the neighboring facilitatory subfields substantially differed in their preferred orientations and spatial frequencies. Over 80% of V2 neurons in both infants and adults had "tuned" suppressive profiles in their subfield maps that could alter the tuning properties of facilitatory profiles. The differences in the preferred orientations between facilitatory and suppressive profiles were relatively large but extended over a broad range. Response immaturities in infants were mild; the overall strength of facilitatory subfield responses was lower than that in adults, and the optimal correlation delay ("latency") was longer in 4-week-old infants. These results suggest that as early as 4 weeks of age, the spatial receptive-field structure of V2 neurons is as complex as in adults and the ability of V2 neurons to compare local features of neighboring stimulus elements is nearly adult like.

  10. Expression of Vesicular Glutamate Transporters Type 1 and 2 in Sensory and Autonomic Neurons Innervating the Mouse Colorectum

    PubMed Central

    Brumovsky, Pablo R.; Robinson, David R.; La, Jun-Ho; Seroogy, Kim B.; Lundgren, Kerstin H.; Albers, Kathryn M.; Kiyatkin, Michael E.; Seal, Rebecca P.; Edwards, Robert H.; Watanabe, Masahiko; Hökfelt, Tomas; Gebhart, G.F.

    2013-01-01

    Vesicular glutamate transporters (VGLUTs) have been extensively studied in various neuronal systems, but their expression in visceral sensory and autonomic neurons remains to be analyzed in detail. Here we studied VGLUTs type 1 and 2 (VGLUT1 and VGLUT2, respectively) in neurons innervating the mouse colorectum. Lumbosacral and thoracolumbar dorsal root ganglion (DRG), lumbar sympathetic chain (LSC), and major pelvic ganglion (MPG) neurons innervating the colorectum of BALB/C mice were retrogradely traced with Fast Blue, dissected, and processed for immunohistochemistry. Tissue from additional naïve mice was included. Previously characterized antibodies against VGLUT1, VGLUT2, and calcitonin gene-related peptide (CGRP) were used. Riboprobe in situ hybridization, using probes against VGLUT1 and VGLUT2, was also performed. Most colorectal DRG neurons expressed VGLUT2 and often colocalized with CGRP. A smaller percentage of neurons expressed VGLUT1. VGLUT2-immunoreactive (IR) neurons in the MPG were rare. Abundant VGLUT2-IR nerves were detected in all layers of the colorectum; VGLUT1-IR nerves were sparse. A subpopulation of myenteric plexus neurons expressed VGLUT2 protein and mRNA, but VGLUT1 mRNA was undetectable. In conclusion, we show 1) that most colorectal DRG neurons express VGLUT2, and to a lesser extent, VGLUT1; 2) abundance of VGLUT2-IR fibers innervating colorectum; and 3) a subpopulation of myenteric plexus neurons expressing VGLUT2. Altogether, our data suggests a role for VGLUT2 in colorectal glutamatergic neurotransmission, potentially influencing colorectal sensitivity and motility. PMID:21800314

  11. Upregulated miR-29b promotes neuronal cell death by inhibiting Bcl2L2 after ischemic brain injury.

    PubMed

    Shi, Guodong; Liu, Yang; Liu, Tielong; Yan, Wangjun; Liu, Xiaowei; Wang, Yuan; Shi, Jiangang; Jia, Lianshun

    2012-01-01

    It is increasingly clear that microRNAs (miRNAs) play an important role in controlling cell survival. However, the functional significance of miRNAs in ischemic brain injury remains poorly understood. In the present study, we assayed the expression levels of miR-29b after ischemic brain injury, and defined the target genes and biological functions of miR-29b. We found that the miR-29b levels were significantly increased in rat brain after transient middle cerebral artery occlusion and neurons after oxygen-glucose deprivation. Moreover, ectopic expression of miR-29b promoted neuronal cell death, whereas its repression decreased cell death. Furthermore, we verified that miR-29b directly targeted and inhibited Bcl2L2 gene expression, and then increased neuronal cell death. Importantly, Bcl2L2 overexpression rescued neuronal cell death induced by miR-29b. These results suggest an important role of miR-29b in regulating neuronal cell death, thus offering a new target for the development of therapeutic agents against ischemic brain injury.

  12. IL-33/ST2 signaling excites sensory neurons and mediates itch response in a mouse model of poison ivy contact allergy.

    PubMed

    Liu, Boyi; Tai, Yan; Achanta, Satyanarayana; Kaelberer, Melanie M; Caceres, Ana I; Shao, Xiaomei; Fang, Jianqiao; Jordt, Sven-Eric

    2016-11-22

    Poison ivy-induced allergic contact dermatitis (ACD) is the most common environmental allergic condition in the United States. Case numbers of poison ivy ACD are increasing due to growing biomass and geographical expansion of poison ivy and increasing content of the allergen, urushiol, likely attributable to rising atmospheric CO 2 Severe and treatment-resistant itch is the major complaint of affected patients. However, because of limited clinical data and poorly characterized models, the pruritic mechanisms in poison ivy ACD remain unknown. Here, we aim to identify the mechanisms of itch in a mouse model of poison ivy ACD by transcriptomics, neuronal imaging, and behavioral analysis. Using transcriptome microarray analysis, we identified IL-33 as a key cytokine up-regulated in the inflamed skin of urushiol-challenged mice. We further found that the IL-33 receptor, ST2, is expressed in small to medium-sized dorsal root ganglion (DRG) neurons, including neurons that innervate the skin. IL-33 induces Ca 2+ influx into a subset of DRG neurons through neuronal ST2. Neutralizing antibodies against IL-33 or ST2 reduced scratching behavior and skin inflammation in urushiol-challenged mice. Injection of IL-33 into urushiol-challenged skin rapidly exacerbated itch-related scratching via ST2, in a histamine-independent manner. Targeted silencing of neuronal ST2 expression by intrathecal ST2 siRNA delivery significantly attenuated pruritic responses caused by urushiol-induced ACD. These results indicate that IL-33/ST2 signaling is functionally present in primary sensory neurons and contributes to pruritus in poison ivy ACD. Blocking IL-33/ST2 signaling may represent a therapeutic approach to ameliorate itch and skin inflammation related to poison ivy ACD.

  13. Reduced sensory synaptic excitation impairs motor neuron function via Kv2.1 in spinal muscular atrophy.

    PubMed

    Fletcher, Emily V; Simon, Christian M; Pagiazitis, John G; Chalif, Joshua I; Vukojicic, Aleksandra; Drobac, Estelle; Wang, Xiaojian; Mentis, George Z

    2017-07-01

    Behavioral deficits in neurodegenerative diseases are often attributed to the selective dysfunction of vulnerable neurons via cell-autonomous mechanisms. Although vulnerable neurons are embedded in neuronal circuits, the contributions of their synaptic partners to disease process are largely unknown. Here we show that, in a mouse model of spinal muscular atrophy (SMA), a reduction in proprioceptive synaptic drive leads to motor neuron dysfunction and motor behavior impairments. In SMA mice or after the blockade of proprioceptive synaptic transmission, we observed a decrease in the motor neuron firing that could be explained by the reduction in the expression of the potassium channel Kv2.1 at the surface of motor neurons. Chronically increasing neuronal activity pharmacologically in vivo led to a normalization of Kv2.1 expression and an improvement in motor function. Our results demonstrate a key role of excitatory synaptic drive in shaping the function of motor neurons during development and the contribution of its disruption to a neurodegenerative disease.

  14. Reduced sensory synaptic excitation impairs motor neuron function via Kv2.1 in spinal muscular atrophy

    PubMed Central

    Fletcher, Emily V.; Simon, Christian M.; Pagiazitis, John G.; Chalif, Joshua I.; Vukojicic, Aleksandra; Drobac, Estelle; Wang, Xiaojian; Mentis, George Z.

    2017-01-01

    Behavioral deficits in neurodegenerative diseases are often attributed to the selective dysfunction of vulnerable neurons via cell-autonomous mechanisms. Although vulnerable neurons are embedded in neuronal circuits, the contribution of their synaptic partners to the disease process is largely unknown. Here, we show that in a mouse model of spinal muscular atrophy (SMA), a reduction in proprioceptive synaptic drive leads to motor neuron dysfunction and motor behavior impairments. In SMA mice or after the blockade of proprioceptive synaptic transmission we observed a decrease in the motor neuron firing which could be explained by the reduction in the expression of the potassium channel Kv2.1 at the surface of motor neurons. Increasing neuronal activity pharmacologically by chronic exposure in vivo led to a normalization of Kv2.1 expression and an improvement in motor function. Our results demonstrate a key role of excitatory synaptic drive in shaping the function of motor neurons during development and the contribution of its disruption to a neurodegenerative disease. PMID:28504671

  15. Phospholipase A2 - nexus of aging, oxidative stress, neuronal excitability, and functional decline of the aging nervous system? Insights from a snail model system of neuronal aging and age-associated memory impairment.

    PubMed

    Hermann, Petra M; Watson, Shawn N; Wildering, Willem C

    2014-01-01

    The aging brain undergoes a range of changes varying from subtle structural and physiological changes causing only minor functional decline under healthy normal aging conditions, to severe cognitive or neurological impairment associated with extensive loss of neurons and circuits due to age-associated neurodegenerative disease conditions. Understanding how biological aging processes affect the brain and how they contribute to the onset and progress of age-associated neurodegenerative diseases is a core research goal in contemporary neuroscience. This review focuses on the idea that changes in intrinsic neuronal electrical excitability associated with (per)oxidation of membrane lipids and activation of phospholipase A2 (PLA2) enzymes are an important mechanism of learning and memory failure under normal aging conditions. Specifically, in the context of this special issue on the biology of cognitive aging we portray the opportunities offered by the identifiable neurons and behaviorally characterized neural circuits of the freshwater snail Lymnaea stagnalis in neuronal aging research and recapitulate recent insights indicating a key role of lipid peroxidation-induced PLA2 as instruments of aging, oxidative stress and inflammation in age-associated neuronal and memory impairment in this model system. The findings are discussed in view of accumulating evidence suggesting involvement of analogous mechanisms in the etiology of age-associated dysfunction and disease of the human and mammalian brain.

  16. Direct projections from hypothalamic orexin neurons to brainstem cardiac vagal neurons.

    PubMed

    Dergacheva, Olga; Yamanaka, Akihiro; Schwartz, Alan R; Polotsky, Vsevolod Y; Mendelowitz, David

    2016-12-17

    Orexin neurons are known to augment the sympathetic control of cardiovascular function, however the role of orexin neurons in parasympathetic cardiac regulation remains unclear. To test the hypothesis that orexin neurons contribute to parasympathetic control we selectively expressed channelrhodopsin-2 (ChR2) in orexin neurons in orexin-Cre transgenic rats and examined postsynaptic currents in cardiac vagal neurons (CVNs) in the dorsal motor nucleus of the vagus (DMV). Simultaneous photostimulation and recording in ChR2-expressing orexin neurons in the lateral hypothalamus resulted in reliable action potential firing as well as large whole-cell currents suggesting a strong expression of ChR2 and reliable optogenetic excitation. Photostimulation of ChR2-expressing fibers in the DMV elicited short-latency (ranging from 3.2ms to 8.5ms) postsynaptic currents in 16 out of 44 CVNs tested. These responses were heterogeneous and included excitatory glutamatergic (63%) and inhibitory GABAergic (37%) postsynaptic currents. The results from this study suggest different sub-population of orexin neurons may exert diverse influences on brainstem CVNs and therefore may play distinct functional roles in parasympathetic control of the heart. Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.

  17. LAT Region Factors Mediating Differential Neuronal Tropism of HSV-1 and HSV-2 Do Not Act in Trans

    PubMed Central

    Bertke, Andrea S.; Apakupakul, Kathleen; Ma, AyeAye; Imai, Yumi; Gussow, Anne M.; Wang, Kening; Cohen, Jeffrey I.; Bloom, David C.; Margolis, Todd P.

    2012-01-01

    After HSV infection, some trigeminal ganglion neurons support productive cycle gene expression, while in other neurons the virus establishes a latent infection. We previously demonstrated that HSV-1 and HSV-2 preferentially establish latent infection in A5+ and KH10+ sensory neurons, respectively, and that exchanging the latency-associated transcript (LAT) between HSV-1 and HSV-2 also exchanges the neuronal preference. Since many viral genes besides the LAT are functionally interchangeable between HSV-1 and HSV-2, we co-infected HSV-1 and HSV-2, both in vivo and in vitro, to determine if trans-acting viral factors regulate whether HSV infection follows a productive or latent pattern of gene expression in sensory neurons. The pattern of HSV-1 and HSV-2 latent infection in trigeminal neurons was no different following co-infection than with either virus alone, consistent with the hypothesis that a trans-acting viral factor is not responsible for the different patterns of latent infection of HSV-1 and HSV-2 in A5+ and KH10+ neurons. Since exchanging the LAT regions between the viruses also exchanges neuronal preferences, we infected transgenic mice that constitutively express 2.8 kb of the LAT region with the heterologous viral serotype. Endogenous expression of LAT did not alter the pattern of latent infection after inoculation with the heterologous serotype virus, demonstrating that the LAT region does not act in trans to direct preferential establishment of latency of HSV-1 and HSV-2. Using HSV1-RFP and HSV2-GFP in adult trigeminal ganglion neurons in vitro, we determined that HSV-1 and HSV-2 do not exert trans-acting effects during acute infection to regulate neuron specificity. Although some neurons were productively infected with both HSV-1 and HSV-2, no A5+ or KH10+ neurons were productively infected with both viruses. Thus, trans-acting viral factors do not regulate preferential permissiveness of A5+ and KH10+ neurons for productive HSV infection and

  18. LAT region factors mediating differential neuronal tropism of HSV-1 and HSV-2 do not act in trans.

    PubMed

    Bertke, Andrea S; Apakupakul, Kathleen; Ma, AyeAye; Imai, Yumi; Gussow, Anne M; Wang, Kening; Cohen, Jeffrey I; Bloom, David C; Margolis, Todd P

    2012-01-01

    After HSV infection, some trigeminal ganglion neurons support productive cycle gene expression, while in other neurons the virus establishes a latent infection. We previously demonstrated that HSV-1 and HSV-2 preferentially establish latent infection in A5+ and KH10+ sensory neurons, respectively, and that exchanging the latency-associated transcript (LAT) between HSV-1 and HSV-2 also exchanges the neuronal preference. Since many viral genes besides the LAT are functionally interchangeable between HSV-1 and HSV-2, we co-infected HSV-1 and HSV-2, both in vivo and in vitro, to determine if trans-acting viral factors regulate whether HSV infection follows a productive or latent pattern of gene expression in sensory neurons. The pattern of HSV-1 and HSV-2 latent infection in trigeminal neurons was no different following co-infection than with either virus alone, consistent with the hypothesis that a trans-acting viral factor is not responsible for the different patterns of latent infection of HSV-1 and HSV-2 in A5+ and KH10+ neurons. Since exchanging the LAT regions between the viruses also exchanges neuronal preferences, we infected transgenic mice that constitutively express 2.8 kb of the LAT region with the heterologous viral serotype. Endogenous expression of LAT did not alter the pattern of latent infection after inoculation with the heterologous serotype virus, demonstrating that the LAT region does not act in trans to direct preferential establishment of latency of HSV-1 and HSV-2. Using HSV1-RFP and HSV2-GFP in adult trigeminal ganglion neurons in vitro, we determined that HSV-1 and HSV-2 do not exert trans-acting effects during acute infection to regulate neuron specificity. Although some neurons were productively infected with both HSV-1 and HSV-2, no A5+ or KH10+ neurons were productively infected with both viruses. Thus, trans-acting viral factors do not regulate preferential permissiveness of A5+ and KH10+ neurons for productive HSV infection and

  19. Enhancement of extinction memory consolidation: the role of the noradrenergic and GABAergic systems within the basolateral amygdala.

    PubMed

    Berlau, Daniel J; McGaugh, James L

    2006-09-01

    Evidence from previous studies indicates that the noradrenergic and GABAergic influences within the basolateral amygdala (BLA) modulate the consolidation of memory for fear conditioning. The present experiments investigated whether the same modulatory influences are involved in regulating the extinction of fear-based learning. To investigate this issue, male Sprague Dawley rats implanted with unilateral or bilateral cannula aimed at the BLA were trained on a contextual fear conditioning (CFC) task and 24 and 48 h later were given extinction training. Immediately following each extinction session they received intra-BLA infusions of the GABAergic antagonist bicuculline (50 ng), the beta-adrenocepter antagonist propranolol (500 ng), bicuculline with propranolol, norepinephrine (NE) (0.3, 1.0, and 3.0 microg), the GABAergic agonist muscimol (125 ng), NE with muscimol or a control solution. To investigate the involvement of the dorsal hippocampus (DH) as a possible target of BLA activation during extinction, other animals were given infusions of muscimol (500 ng) via an ipsilateral cannula implanted in the DH. Bilateral BLA infusions of bicuculline significantly enhanced extinction, as did infusions into the right, but not left BLA. Propranolol infused into the right BLA together with bicuculline blocked the bicuculline-induced memory enhancement. Norepinephrine infused into the right BLA also enhanced extinction, and this effect was not blocked by co-infusions of muscimol. Additionally, muscimol infused into the DH did not attenuate the memory enhancing effects of norepinephrine infused into the BLA. These findings provide evidence that, as with original CFC learning, noradrenergic activation within the BLA modulates the consolidation of CFC extinction. The findings also suggest that the BLA influence on extinction is not mediated by an interaction with the dorsal hippocampus.

  20. Distinctive features of Phox2b-expressing neurons in the rat reticular formation dorsal to the trigeminal motor nucleus.

    PubMed

    Nagoya, Kouta; Nakamura, Shiro; Ikeda, Keiko; Onimaru, Hiroshi; Yoshida, Atsushi; Nakayama, Kiyomi; Mochizuki, Ayako; Kiyomoto, Masaaki; Sato, Fumihiko; Kawakami, Kiyoshi; Takahashi, Koji; Inoue, Tomio

    2017-09-01

    Phox2b encodes a paired-like homeodomain-containing transcription factor essential for development of the autonomic nervous system. Phox2b-expressing (Phox2b + ) neurons are present in the reticular formation dorsal to the trigeminal motor nucleus (RdV) as well as the nucleus of the solitary tract and parafacial respiratory group. However, the nature of Phox2b + RdV neurons is still unclear. We investigated the physiological and morphological properties of Phox2b + RdV neurons using postnatal day 2-7 transgenic rats expressing yellow fluorescent protein under the control of Phox2b. Almost all of Phox2b + RdV neurons were glutamatergic, whereas Phox2b-negative (Phox2b - ) RdV neurons consisted of a few glutamatergic, many GABAergic, and many glycinergic neurons. The majority (48/56) of Phox2b + neurons showed low-frequency firing (LF), while most of Phox2b - neurons (35/42) exhibited high-frequency firing (HF) in response to intracellularly injected currents. All, but one, Phox2b + neurons (55/56) did not fire spontaneously, whereas three-fourths of the Phox2b - neurons (31/42) were spontaneously active. K + channel and persistent Na + current blockers affected the firing of LF and HF neurons. The majority of Phox2b + (35/46) and half of the Phox2b - neurons (19/40) did not respond to stimulations of the mesencephalic trigeminal nucleus, the trigeminal tract, and the principal sensory trigeminal nucleus. Biocytin labeling revealed that about half of the Phox2b + (5/12) and Phox2b - RdV neurons (5/10) send their axons to the trigeminal motor nucleus. These results suggest that Phox2b + RdV neurons have distinct neurotransmitter phenotypes and firing properties from Phox2b - RdV neurons and might play important roles in feeding-related functions including suckling and possibly mastication. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

  1. Trigeminal ganglion neuron subtype-specific alterations of CaV2.1 calcium current and excitability in a Cacna1a mouse model of migraine

    PubMed Central

    Fioretti, B; Catacuzzeno, L; Sforna, L; Gerke-Duncan, M B; van den Maagdenberg, A M J M; Franciolini, F; Connor, M; Pietrobon, D

    2011-01-01

    Abstract Familial hemiplegic migraine type-1 (FHM1), a monogenic subtype of migraine with aura, is caused by gain-of-function mutations in CaV2.1 (P/Q-type) calcium channels. The consequences of FHM1 mutations on the trigeminovascular pathway that generates migraine headache remain largely unexplored. Here we studied the calcium currents and excitability properties of two subpopulations of small-diameter trigeminal ganglion (TG) neurons from adult wild-type (WT) and R192Q FHM1 knockin (KI) mice: capsaicin-sensitive neurons without T-type calcium currents (CS) and capsaicin-insensitive neurons characterized by the expression of T-type calcium currents (CI-T). Small TG neurons retrogradely labelled from the dura are mostly CS neurons, while CI-T neurons were not present in the labelled population. CS and CI-T neurons express CaV2.1 channels with different activation properties, and the CaV2.1 channels are differently affected by the FHM1 mutation in the two TG neuron subtypes. In CI-T neurons from FHM1 KI mice there was a larger P/Q-type current density following mild depolarizations, a larger action potential (AP)-evoked calcium current and a longer AP duration when compared to CI-T neurons from WT mice. In striking contrast, the P/Q-type current density, voltage dependence and kinetics were not altered by the FHM1 mutation in CS neurons. The excitability properties of mutant CS neurons were also unaltered. Congruently, the FHM1 mutation did not alter depolarization-evoked CGRP release from the dura mater, while CGRP release from the trigeminal ganglion was larger in KI compared to WT mice. Our findings suggest that the facilitation of peripheral mechanisms of CGRP action, such as dural vasodilatation and nociceptor sensitization at the meninges, does not contribute to the generation of headache in FHM1. PMID:22005682

  2. Electrical and Ca2+ signaling in dendritic spines of substantia nigra dopaminergic neurons

    PubMed Central

    Hage, Travis A; Sun, Yujie; Khaliq, Zayd M

    2016-01-01

    Little is known about the density and function of dendritic spines on midbrain dopamine neurons, or the relative contribution of spine and shaft synapses to excitability. Using Ca2+ imaging, glutamate uncaging, fluorescence recovery after photobleaching and transgenic mice expressing labeled PSD-95, we comparatively analyzed electrical and Ca2+ signaling in spines and shaft synapses of dopamine neurons. Dendritic spines were present on dopaminergic neurons at low densities in live and fixed tissue. Uncaging-evoked potential amplitudes correlated inversely with spine length but positively with the presence of PSD-95. Spine Ca2+ signals were less sensitive to hyperpolarization than shaft synapses, suggesting amplification of spine head voltages. Lastly, activating spines during pacemaking, we observed an unexpected enhancement of spine Ca2+ midway throughout the spike cycle, likely involving recruitment of NMDA receptors and voltage-gated conductances. These results demonstrate functionality of spines in dopamine neurons and reveal a novel modulation of spine Ca2+ signaling during pacemaking. DOI: http://dx.doi.org/10.7554/eLife.13905.001 PMID:27163179

  3. Vasculo-Neuronal Coupling: Retrograde Vascular Communication to Brain Neurons.

    PubMed

    Kim, Ki Jung; Ramiro Diaz, Juan; Iddings, Jennifer A; Filosa, Jessica A

    2016-12-14

    Continuous cerebral blood flow is essential for neuronal survival, but whether vascular tone influences resting neuronal function is not known. Using a multidisciplinary approach in both rat and mice brain slices, we determined whether flow/pressure-evoked increases or decreases in parenchymal arteriole vascular tone, which result in arteriole constriction and dilation, respectively, altered resting cortical pyramidal neuron activity. We present evidence for intercellular communication in the brain involving a flow of information from vessel to astrocyte to neuron, a direction opposite to that of classic neurovascular coupling and referred to here as vasculo-neuronal coupling (VNC). Flow/pressure increases within parenchymal arterioles increased vascular tone and simultaneously decreased resting pyramidal neuron firing activity. On the other hand, flow/pressure decreases evoke parenchymal arteriole dilation and increased resting pyramidal neuron firing activity. In GLAST-CreERT2; R26-lsl-GCaMP3 mice, we demonstrate that increased parenchymal arteriole tone significantly increased intracellular calcium in perivascular astrocyte processes, the onset of astrocyte calcium changes preceded the inhibition of cortical pyramidal neuronal firing activity. During increases in parenchymal arteriole tone, the pyramidal neuron response was unaffected by blockers of nitric oxide, GABA A , glutamate, or ecto-ATPase. However, VNC was abrogated by TRPV4 channel, GABA B , as well as an adenosine A 1 receptor blocker. Differently to pyramidal neuron responses, increases in flow/pressure within parenchymal arterioles increased the firing activity of a subtype of interneuron. Together, these data suggest that VNC is a complex constitutive active process that enables neurons to efficiently adjust their resting activity according to brain perfusion levels, thus safeguarding cellular homeostasis by preventing mismatches between energy supply and demand. We present evidence for vessel-to-neuron

  4. Canonical TGF-β Signaling Negatively Regulates Neuronal Morphogenesis through TGIF/Smad Complex-Mediated CRMP2 Suppression.

    PubMed

    Nakashima, Hideyuki; Tsujimura, Keita; Irie, Koichiro; Ishizu, Masataka; Pan, Miao; Kameda, Tomonori; Nakashima, Kinichi

    2018-05-16

    Functional neuronal connectivity requires proper neuronal morphogenesis and its dysregulation causes neurodevelopmental diseases. Transforming growth factor-β (TGF-β) family cytokines play pivotal roles in development, but little is known about their contribution to morphological development of neurons. Here we show that the Smad-dependent canonical signaling of TGF-β family cytokines negatively regulates neuronal morphogenesis during brain development. Mechanistically, activated Smads form a complex with transcriptional repressor TG-interacting factor (TGIF), and downregulate the expression of a neuronal polarity regulator, collapsin response mediator protein 2. We also demonstrate that TGF-β family signaling inhibits neurite elongation of human induced pluripotent stem cell-derived neurons. Furthermore, the expression of TGF-β receptor 1, Smad4, or TGIF, which have mutations found in patients with neurodevelopmental disorders, disrupted neuronal morphogenesis in both mouse (male and female) and human (female) neurons. Together, these findings suggest that the regulation of neuronal morphogenesis by an evolutionarily conserved function of TGF-β signaling is involved in the pathogenesis of neurodevelopmental diseases. SIGNIFICANCE STATEMENT Canonical transforming growth factor-β (TGF-β) signaling plays a crucial role in multiple organ development, including brain, and mutations in components of the signaling pathway associated with several human developmental disorders. In this study, we found that Smads/TG-interacting factor-dependent canonical TGF-β signaling regulates neuronal morphogenesis through the suppression of collapsin response mediator protein-2 (CRMP2) expression during brain development, and that function of this signaling is evolutionarily conserved in the mammalian brain. Mutations in canonical TGF-β signaling factors identified in patients with neurodevelopmental disorders disrupt the morphological development of neurons. Thus, our

  5. Neurons other than motor neurons in motor neuron disease.

    PubMed

    Ruffoli, Riccardo; Biagioni, Francesca; Busceti, Carla L; Gaglione, Anderson; Ryskalin, Larisa; Gambardella, Stefano; Frati, Alessandro; Fornai, Francesco

    2017-11-01

    Amyotrophic lateral sclerosis (ALS) is typically defined by a loss of motor neurons in the central nervous system. Accordingly, morphological analysis for decades considered motor neurons (in the cortex, brainstem and spinal cord) as the neuronal population selectively involved in ALS. Similarly, this was considered the pathological marker to score disease severity ex vivo both in patients and experimental models. However, the concept of non-autonomous motor neuron death was used recently to indicate the need for additional cell types to produce motor neuron death in ALS. This means that motor neuron loss occurs only when they are connected with other cell types. This concept originally emphasized the need for resident glia as well as non-resident inflammatory cells. Nowadays, the additional role of neurons other than motor neurons emerged in the scenario to induce non-autonomous motor neuron death. In fact, in ALS neurons diverse from motor neurons are involved. These cells play multiple roles in ALS: (i) they participate in the chain of events to produce motor neuron loss; (ii) they may even degenerate more than and before motor neurons. In the present manuscript evidence about multi-neuronal involvement in ALS patients and experimental models is discussed. Specific sub-classes of neurons in the whole spinal cord are reported either to degenerate or to trigger neuronal degeneration, thus portraying ALS as a whole spinal cord disorder rather than a disease affecting motor neurons solely. This is associated with a novel concept in motor neuron disease which recruits abnormal mechanisms of cell to cell communication.

  6. Involvement of brain ketone bodies and the noradrenergic pathway in diabetic hyperphagia in rats.

    PubMed

    Iwata, Kinuyo; Kinoshita, Mika; Yamada, Shunji; Imamura, Takuya; Uenoyama, Yoshihisa; Tsukamura, Hiroko; Maeda, Kei-Ichiro

    2011-03-01

    Uncontrolled type 1 diabetes leads to hyperphagia and severe ketosis. This study was conducted to test the hypothesis that ketone bodies act on the hindbrain as a starvation signal to induce diabetic hyperphagia. Injection of an inhibitor of monocarboxylate transporter 1, a ketone body transporter, into the fourth ventricle normalized the increase in food intake in streptozotocin (STZ)-induced diabetic rats. Blockade of catecholamine synthesis in the hypothalamic paraventricular nucleus (PVN) also restored food intake to normal levels in diabetic animals. On the other hand, hindbrain injection of the ketone body induced feeding, hyperglycemia, and fatty acid mobilization via increased sympathetic activity and also norepinephrine release in the PVN. This result provides evidence that hyperphagia in STZ-induced type 1 diabetes is signaled by a ketone body sensed in the hindbrain, and mediated by noradrenergic inputs to the PVN.

  7. The E2A splice variant E47 regulates the differentiation of projection neurons via p57(KIP2) during cortical development.

    PubMed

    Pfurr, Sabrina; Chu, Yu-Hsuan; Bohrer, Christian; Greulich, Franziska; Beattie, Robert; Mammadzada, Könül; Hils, Miriam; Arnold, Sebastian J; Taylor, Verdon; Schachtrup, Kristina; Uhlenhaut, N Henriette; Schachtrup, Christian

    2017-11-01

    During corticogenesis, distinct classes of neurons are born from progenitor cells located in the ventricular and subventricular zones, from where they migrate towards the pial surface to assemble into highly organized layer-specific circuits. However, the precise and coordinated transcriptional network activity defining neuronal identity is still not understood. Here, we show that genetic depletion of the basic helix-loop-helix (bHLH) transcription factor E2A splice variant E47 increased the number of Tbr1-positive deep layer and Satb2-positive upper layer neurons at E14.5, while depletion of the alternatively spliced E12 variant did not affect layer-specific neurogenesis. While ChIP-Seq identified a big overlap for E12- and E47-specific binding sites in embryonic NSCs, including sites at the cyclin-dependent kinase inhibitor (CDKI) Cdkn1c gene locus, RNA-Seq revealed a unique transcriptional regulation by each splice variant. E47 activated the expression of the CDKI Cdkn1c through binding to a distal enhancer. Finally, overexpression of E47 in embryonic NSCs in vitro impaired neurite outgrowth, and overexpression of E47 in vivo by in utero electroporation disturbed proper layer-specific neurogenesis and upregulated p57(KIP2) expression. Overall, this study identifies E2A target genes in embryonic NSCs and demonstrates that E47 regulates neuronal differentiation via p57(KIP2). © 2017. Published by The Company of Biologists Ltd.

  8. Bach2 is involved in neuronal differentiation of N1E-115 neuroblastoma cells.

    PubMed

    Shim, Ki Shuk; Rosner, Margit; Freilinger, Angelika; Lubec, Gert; Hengstschläger, Markus

    2006-07-15

    Bach1 and Bach2 are evolutionarily related members of the BTB-basic region leucine zipper transcription factor family. We found that Bach2 downregulates cell proliferation of N1E-115 cells and negatively affects their potential to differentiate. Nuclear localization of the cyclin-dependent kinase inhibitor p21 is known to arrest cell cycle progression, and cytoplasmic p21 has been shown to promote neuronal differentiation of N1E-115 cells. We found that ectopic Bach2 causes upregulation of p21 expression in the nucleus and in the cytoplasm in undifferentiated N1E-115 cells. In differentiated cells, Bach2 specifically triggers upregulation of cytoplasmic p21. Our data suggest that Bach2 expression could represent a switch during the process of neuronal differentiation. Bach2 is not expressed in neuronal precursor cells. It would have negative effects on proliferation and differentiation of these cells. In differentiated neuronal cells Bach2 expression is upregulated, which could allow Bach2 to function as a gatekeeper of the differentiated status.

  9. KCC2-dependent Steady-state Intracellular Chloride Concentration and pH in Cortical Layer 2/3 Neurons of Anesthetized and Awake Mice.

    PubMed

    Boffi, Juan C; Knabbe, Johannes; Kaiser, Michaela; Kuner, Thomas

    2018-01-01

    Neuronal intracellular Cl - concentration ([Cl - ] i ) influences a wide range of processes such as neuronal inhibition, membrane potential dynamics, intracellular pH (pH i ) or cell volume. Up to date, neuronal [Cl - ] i has predominantly been studied in model systems of reduced complexity. Here, we implemented the genetically encoded ratiometric Cl - indicator Superclomeleon (SCLM) to estimate the steady-state [Cl - ] i in cortical neurons from anesthetized and awake mice using 2-photon microscopy. Additionally, we implemented superecliptic pHluorin (SE-pHluorin) as a ratiometric sensor to estimate the intracellular steady-state pH (pH i ) of mouse cortical neurons in vivo . We estimated an average resting [Cl - ] i of 6 ± 2 mM with no evidence of subcellular gradients in the proximal somato-dendritic domain and an average somatic pH i of 7.1 ± 0.2. Neither [Cl - ] i nor pH i were affected by isoflurane anesthesia. We deleted the cation-Cl - co-transporter KCC2 in single identified neurons of adult mice and found an increase of [Cl - ] i to approximately 26 ± 8 mM, demonstrating that under in vivo conditions KCC2 produces low [Cl - ] i in adult mouse neurons. In summary, neurons of the brain of awake adult mice exhibit a low and evenly distributed [Cl - ] i in the proximal somato-dendritic compartment that is independent of anesthesia and requires KCC2 expression for its maintenance.

  10. Possible involvement of transient receptor potential ankyrin 1 in Ca2+ signaling via T-type Ca2+ channel in mouse sensory neurons.

    PubMed

    Nishizawa, Yuki; Takahashi, Kenji; Oguma, Naoko; Tominaga, Makoto; Ohta, Toshio

    2018-05-01

    T-type Ca 2+ channels and TRPA1 are expressed in sensory neurons and both are associated with pain transmission, but their functional interaction is unclear. Here we demonstrate that pharmacological evidence of the functional relation between T-type Ca 2+ channels and TRPA1 in mouse sensory neurons. Low concentration of KCl at 15 mM (15K) evoked increases of intracellular Ca 2+ concentration ([Ca 2+ ] i ), which were suppressed by selective T-type Ca 2+ channel blockers. RT-PCR showed that mouse sensory neurons expressed all subtypes of T-type Ca 2+ channel. The magnitude of 15K-induced [Ca 2+ ] i increase was significantly larger in neurons sensitive to allylisothiocyanate (AITC, a TRPA1 agonist) than in those insensitive to it, and in TRPA1 -/- mouse sensory neurons. TRPA1 blockers diminished the [Ca 2+ ] i responses to 15K in neurons sensitive to AITC, but failed to inhibit 40 mM KCl-induced [Ca 2+ ] i increases even in AITC-sensitive neurons. TRPV1 blockers did not inhibit the 15K-induced [Ca 2+ ] i increase regardless of the sensitivity to capsaicin. [Ca 2+ ] i responses to TRPA1 agonist were enhanced by co-application with 15K. These pharmacological data suggest the possibility of functional interaction between T-type Ca 2+ channels and TRPA1 in sensory neurons. Since TRPA1 channel is activated by intracellular Ca 2+ , we hypothesize that Ca 2+ entered via T-type Ca 2+ channel activation may further stimulate TRPA1, resulting in an enhancement of nociceptive signaling. Thus, T-type Ca 2+ channel may be a potential target for TRPA1-related pain. © 2017 Wiley Periodicals, Inc.

  11. Neuronal nitric oxide synthase immunopositive neurons in cat claustrum--a light and electron microscopic study.

    PubMed

    Hinova-Palova, Dimka; Edelstein, Lawrence; Paloff, Adrian; Hristov, Stanislav; Papantchev, Vassil; Ovtscharoff, Wladimir

    2008-08-01

    Nitric oxide is a unique neurotransmitter, which participates in many physiological and pathological processes in the organism. Nevertheless there are little data about the neuronal Nitric Oxide Synthase immunoreactive (nNOS-ir) neurons and fibers in the dorsal claustrum (DC) of a cat. In this respect the aims of this study were: (1) to demonstrate nNOS-ir in the neurons and fibers of the DC; (2) to describe their light microscopic morphology and distribution; (3) to investigate and analyze the ultrastructure of the nNOS-ir neurons, fibers and synaptic terminals; (4) to verify whether the nNOS-ir neurons consist a specific subpopulation of claustral neurons; (5) to verify whether the nNOS-ir neurons have a specific pattern of organization throughout the DC. For demonstration of the nNOS-ir the Avidin-Biotin-Peroxidase Complex method was applied. Immunopositive for nNOS neurons and fibers were present in all parts of DC. On the light microscope level nNOS-ir neurons were different in shape and size. According to the latter they were divided into three groups-small (with diameter under 15 microm), medium-sized (with diameter from 16 to 20 microm) and large (with diameter over 21 microm). Some of nNOS-ir neurons were lightly-stained while others were darkly-stained. On the electron microscope level the immunoproduct was observed in neurons, dendrites and terminal boutons. Different types of nNOS-ir neurons differ according to their ultrastructural features. Three types of nNOS-ir synaptic boutons were found. As a conclusion we hope that the present study will contribute to a better understanding of the functioning of the DC in cat and that some of the data presented could be extrapolated to other mammals, including human.

  12. IL-33/ST2 signaling excites sensory neurons and mediates itch response in a mouse model of poison ivy contact allergy

    PubMed Central

    Liu, Boyi; Tai, Yan; Achanta, Satyanarayana; Kaelberer, Melanie M.; Caceres, Ana I.; Shao, Xiaomei; Fang, Jianqiao; Jordt, Sven-Eric

    2016-01-01

    Poison ivy-induced allergic contact dermatitis (ACD) is the most common environmental allergic condition in the United States. Case numbers of poison ivy ACD are increasing due to growing biomass and geographical expansion of poison ivy and increasing content of the allergen, urushiol, likely attributable to rising atmospheric CO2. Severe and treatment-resistant itch is the major complaint of affected patients. However, because of limited clinical data and poorly characterized models, the pruritic mechanisms in poison ivy ACD remain unknown. Here, we aim to identify the mechanisms of itch in a mouse model of poison ivy ACD by transcriptomics, neuronal imaging, and behavioral analysis. Using transcriptome microarray analysis, we identified IL-33 as a key cytokine up-regulated in the inflamed skin of urushiol-challenged mice. We further found that the IL-33 receptor, ST2, is expressed in small to medium-sized dorsal root ganglion (DRG) neurons, including neurons that innervate the skin. IL-33 induces Ca2+ influx into a subset of DRG neurons through neuronal ST2. Neutralizing antibodies against IL-33 or ST2 reduced scratching behavior and skin inflammation in urushiol-challenged mice. Injection of IL-33 into urushiol-challenged skin rapidly exacerbated itch-related scratching via ST2, in a histamine-independent manner. Targeted silencing of neuronal ST2 expression by intrathecal ST2 siRNA delivery significantly attenuated pruritic responses caused by urushiol-induced ACD. These results indicate that IL-33/ST2 signaling is functionally present in primary sensory neurons and contributes to pruritus in poison ivy ACD. Blocking IL-33/ST2 signaling may represent a therapeutic approach to ameliorate itch and skin inflammation related to poison ivy ACD. PMID:27821781

  13. Eukaryotic elongation factor 2 kinase regulates the synthesis of microtubule-related proteins in neurons.

    PubMed

    Kenney, Justin W; Genheden, Maja; Moon, Kyung-Mee; Wang, Xuemin; Foster, Leonard J; Proud, Christopher G

    2016-01-01

    Modulation of the elongation phase of protein synthesis is important for numerous physiological processes in both neurons and other cell types. Elongation is primarily regulated via eukaryotic elongation factor 2 kinase (eEF2K). However, the consequence of altering eEF2K activity on the synthesis of specific proteins is largely unknown. Using both pharmacological and genetic manipulations of eEF2K combined with two protein-labeling techniques, stable isotope labeling of amino acids in cell culture and bio-orthogonal non-canonical amino acid tagging, we identified a subset of proteins whose synthesis is sensitive to inhibition of eEF2K in murine primary cortical neurons. Gene ontology (GO) analyses indicated that processes related to microtubules are particularly sensitive to eEF2K inhibition. Our findings suggest that eEF2K likely contributes to neuronal function by regulating the synthesis of microtubule-related proteins. Modulation of the elongation phase of protein synthesis is important for numerous physiological processes in neurons. Here, using labeling of new proteins coupled with proteomic techniques in primary cortical neurons, we find that the synthesis of microtubule-related proteins is up-regulated by inhibition of elongation. This suggests that translation elongation is a key regulator of cytoskeletal dynamics in neurons. © 2015 The Authors. Journal of Neurochemistry published by John Wiley & Sons Ltd on behalf of International Society for Neurochemistry.

  14. DeepNeuron: an open deep learning toolbox for neuron tracing.

    PubMed

    Zhou, Zhi; Kuo, Hsien-Chi; Peng, Hanchuan; Long, Fuhui

    2018-06-06

    Reconstructing three-dimensional (3D) morphology of neurons is essential for understanding brain structures and functions. Over the past decades, a number of neuron tracing tools including manual, semiautomatic, and fully automatic approaches have been developed to extract and analyze 3D neuronal structures. Nevertheless, most of them were developed based on coding certain rules to extract and connect structural components of a neuron, showing limited performance on complicated neuron morphology. Recently, deep learning outperforms many other machine learning methods in a wide range of image analysis and computer vision tasks. Here we developed a new Open Source toolbox, DeepNeuron, which uses deep learning networks to learn features and rules from data and trace neuron morphology in light microscopy images. DeepNeuron provides a family of modules to solve basic yet challenging problems in neuron tracing. These problems include but not limited to: (1) detecting neuron signal under different image conditions, (2) connecting neuronal signals into tree(s), (3) pruning and refining tree morphology, (4) quantifying the quality of morphology, and (5) classifying dendrites and axons in real time. We have tested DeepNeuron using light microscopy images including bright-field and confocal images of human and mouse brain, on which DeepNeuron demonstrates robustness and accuracy in neuron tracing.

  15. Mild Traumatic Brain Injury Produces Neuron Loss That Can Be Rescued by Modulating Microglial Activation Using a CB2 Receptor Inverse Agonist

    PubMed Central

    Bu, Wei; Ren, Huiling; Deng, Yunping; Del Mar, Nobel; Guley, Natalie M.; Moore, Bob M.; Honig, Marcia G.; Reiner, Anton

    2016-01-01

    We have previously reported that mild TBI created by focal left-side cranial blast in mice produces widespread axonal injury, microglial activation, and a variety of functional deficits. We have also shown that these functional deficits are reduced by targeting microglia through their cannabinoid type-2 (CB2) receptors using 2-week daily administration of the CB2 inverse agonist SMM-189. CB2 inverse agonists stabilize the G-protein coupled CB2 receptor in an inactive conformation, leading to increased phosphorylation and nuclear translocation of the cAMP response element binding protein (CREB), and thus bias activated microglia from a pro-inflammatory M1 to a pro-healing M2 state. In the present study, we showed that SMM-189 boosts nuclear pCREB levels in microglia in several brain regions by 3 days after TBI, by using pCREB/CD68 double immunofluorescent labeling. Next, to better understand the basis of motor deficits and increased fearfulness after TBI, we used unbiased stereological methods to characterize neuronal loss in cortex, striatum, and basolateral amygdala (BLA) and assessed how neuronal loss was affected by SMM-189 treatment. Our stereological neuron counts revealed a 20% reduction in cortical and 30% reduction in striatal neurons bilaterally at 2–3 months post blast, with SMM-189 yielding about 50% rescue. Loss of BLA neurons was restricted to the blast side, with 33% of Thy1+ fear-suppressing pyramidal neurons and 47% of fear-suppressing parvalbuminergic (PARV) interneurons lost, and Thy1-negative fear-promoting pyramidal neurons not significantly affected. SMM-189 yielded 50–60% rescue of Thy1+ and PARV neuron loss in BLA. Thus, fearfulness after mild TBI may result from the loss of fear-suppressing neuron types in BLA, and SMM-189 may reduce fearfulness by their rescue. Overall, our findings indicate that SMM-189 rescues damaged neurons and thereby alleviates functional deficits resulting from TBI, apparently by selectively modulating microglia

  16. Synaptically activated Ca2+ waves in layer 2/3 and layer 5 rat neocortical pyramidal neurons

    PubMed Central

    Larkum, Matthew E; Watanabe, Shigeo; Nakamura, Takeshi; Lasser-Ross, Nechama; Ross, William N

    2003-01-01

    Calcium waves in layer 2/3 and layer 5 neocortical somatosensory pyramidal neurons were examined in slices from 2- to 8-week-old rats. Repetitive synaptic stimulation evoked a delayed, all-or-none [Ca2+]i increase primarily on the main dendritic shaft. This component was blocked by 1 mm (R,S)-α-methyl-4-carboxyphenylglycine (MCPG), 10 μm ryanodine, 1 mg ml−1 internal heparin, and was not blocked by 400 μm internal Ruthenium Red, indicating that it was due to Ca2+ release from internal stores by inositol 1,4,5-trisphosphate (IP3) mobilized via activation of metabotropic glutamate receptors. Calcium waves were initiated on the apical shaft at sites between the soma to around the main branch point, mostly at insertion points of oblique dendrites, and spread in both directions along the shaft. In the proximal dendrites the peak amplitude of the resulting [Ca2+]i change was much larger than that evoked by a train of Na+ spikes. In distal dendrites the peak amplitude was comparable to the [Ca2+]i change due to a Ca2+ spike. IP3-mediated Ca2+ release also was observed in the presence of the metabotropic agonists t-ACPD and carbachol when backpropagating spikes were generated. Ca2+ entry through NMDA receptors was observed primarily on the oblique dendrites. The main differences between waves in neocortical neurons and in previously described hippocampal pyramidal neurons were, (a) Ca2+ waves in L5 neurons could be evoked further out along the main shaft, (b) Ca2+ waves extended slightly further out into the oblique dendrites and (c) higher concentrations of bath-applied t-ACPD and carbachol were required to generate Ca2+ release events by backpropagating action potentials. PMID:12692172

  17. A Mammalian Conserved Element Derived from SINE Displays Enhancer Properties Recapitulating Satb2 Expression in Early-Born Callosal Projection Neurons

    PubMed Central

    Nakanishi, Akiko; Sasaki, Takeshi; Yan, Kuo; Tarabykin, Victor; Vigier, Lisa; Sumiyama, Kenta; Hirakawa, Mika; Nishihara, Hidenori; Pierani, Alessandra; Okada, Norihiro

    2011-01-01

    Short interspersed repetitive elements (SINEs) are highly repeated sequences that account for a significant proportion of many eukaryotic genomes and are usually considered “junk DNA”. However, we previously discovered that many AmnSINE1 loci are evolutionarily conserved across mammalian genomes, suggesting that they may have acquired significant functions involved in controlling mammalian-specific traits. Notably, we identified the AS021 SINE locus, located 390 kbp upstream of Satb2. Using transgenic mice, we showed that this SINE displays specific enhancer activity in the developing cerebral cortex. The transcription factor Satb2 is expressed by cortical neurons extending axons through the corpus callosum and is a determinant of callosal versus subcortical projection. Mouse mutants reveal a crucial function for Sabt2 in corpus callosum formation. In this study, we compared the enhancer activity of the AS021 locus with Satb2 expression during telencephalic development in the mouse. First, we showed that the AS021 enhancer is specifically activated in early-born Satb2+ neurons. Second, we demonstrated that the activity of the AS021 enhancer recapitulates the expression of Satb2 at later embryonic and postnatal stages in deep-layer but not superficial-layer neurons, suggesting the possibility that the expression of Satb2 in these two subpopulations of cortical neurons is under genetically distinct transcriptional control. Third, we showed that the AS021 enhancer is activated in neurons projecting through the corpus callosum, as described for Satb2+ neurons. Notably, AS021 drives specific expression in axons crossing through the ventral (TAG1−/NPY+) portion of the corpus callosum, confirming that it is active in a subpopulation of callosal neurons. These data suggest that exaptation of the AS021 SINE locus might be involved in enhancement of Satb2 expression, leading to the establishment of interhemispheric communication via the corpus callosum, a eutherian

  18. The neuronal Ca(2+) -binding protein 2 (NECAB2) interacts with the adenosine A(2A) receptor and modulates the cell surface expression and function of the receptor.

    PubMed

    Canela, Laia; Luján, Rafael; Lluís, Carme; Burgueño, Javier; Mallol, Josefa; Canela, Enric I; Franco, Rafael; Ciruela, Francisco

    2007-09-01

    Heptaspanning membrane also known as G protein-coupled receptors (GPCR) do interact with a variety of intracellular proteins whose function is regulate receptor traffic and/or signaling. Using a yeast two-hybrid screen, NECAB2, a neuronal calcium binding protein, was identified as a binding partner for the adenosine A(2A) receptor (A(2A)R) interacting with its C-terminal domain. Co-localization, co-immunoprecipitation and pull-down experiments showed a close and specific interaction between A(2A)R and NECAB2 in both transfected HEK-293 cells and also in rat striatum. Immunoelectron microscopy detection of NECAB2 and A(2A)R in the rat striatopallidal structures indicated that both proteins are co-distributed in the same glutamatergic nerve terminals. The interaction of NECAB2 with A(2A)R modulated the cell surface expression, the ligand-dependent internalization and the receptor-mediated activation of the MAPK pathway. Overall, these results show that A(2A)R interacts with NECAB2 in striatal neurones co-expressing the two proteins and that the interaction is relevant for A(2A)R function.

  19. NeuronMetrics: software for semi-automated processing of cultured neuron images.

    PubMed

    Narro, Martha L; Yang, Fan; Kraft, Robert; Wenk, Carola; Efrat, Alon; Restifo, Linda L

    2007-03-23

    Using primary cell culture to screen for changes in neuronal morphology requires specialized analysis software. We developed NeuronMetrics for semi-automated, quantitative analysis of two-dimensional (2D) images of fluorescently labeled cultured neurons. It skeletonizes the neuron image using two complementary image-processing techniques, capturing fine terminal neurites with high fidelity. An algorithm was devised to span wide gaps in the skeleton. NeuronMetrics uses a novel strategy based on geometric features called faces to extract a branch number estimate from complex arbors with numerous neurite-to-neurite contacts, without creating a precise, contact-free representation of the neurite arbor. It estimates total neurite length, branch number, primary neurite number, territory (the area of the convex polygon bounding the skeleton and cell body), and Polarity Index (a measure of neuronal polarity). These parameters provide fundamental information about the size and shape of neurite arbors, which are critical factors for neuronal function. NeuronMetrics streamlines optional manual tasks such as removing noise, isolating the largest primary neurite, and correcting length for self-fasciculating neurites. Numeric data are output in a single text file, readily imported into other applications for further analysis. Written as modules for ImageJ, NeuronMetrics provides practical analysis tools that are easy to use and support batch processing. Depending on the need for manual intervention, processing time for a batch of approximately 60 2D images is 1.0-2.5 h, from a folder of images to a table of numeric data. NeuronMetrics' output accelerates the quantitative detection of mutations and chemical compounds that alter neurite morphology in vitro, and will contribute to the use of cultured neurons for drug discovery.

  20. Zn2+ reduction induces neuronal death with changes in voltage-gated potassium and sodium channel currents.

    PubMed

    Tian, Kun; He, Cong-Cong; Xu, Hui-Nan; Wang, Yu-Xiang; Wang, Hong-Gang; An, Di; Heng, Bin; Pang, Wei; Jiang, Yu-Gang; Liu, Yan-Qiang

    2017-05-01

    In the present study, cultured rat primary neurons were exposed to a medium containing N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN), a specific cell membrane-permeant Zn 2+ chelator, to establish a model of free Zn 2+ deficiency in neurons. The effects of TPEN-mediated free Zn 2+ ion reduction on neuronal viability and on the performance of voltage-gated sodium channels (VGSCs) and potassium channels (Kvs) were assessed. Free Zn 2+ deficiency 1) markedly reduced the neuronal survival rate, 2) reduced the peak amplitude of I Na , 3) shifted the I Na activation curve towards depolarization, 4) modulated the sensitivity of sodium channel voltage-dependent inactivation to a depolarization voltage, and 5) increased the time course of recovery from sodium channel inactivation. In addition, free Zn 2+ deficiency by TPEN notably enhanced the peak amplitude of transient outward K + currents (I A ) and delayed rectifier K + currents (I K ), as well as caused hyperpolarization and depolarization directional shifts in their steady-state activation curves, respectively. Zn 2+ supplementation reversed the effects induced by TPEN. Our results indicate that free Zn 2+ deficiency causes neuronal damage and alters the dynamic characteristics of VGSC and Kv currents. Thus, neuronal injury caused by free Zn 2+ deficiency may correlate with its modulation of the electrophysiological properties of VGSCs and Kvs. Copyright © 2017 Elsevier GmbH. All rights reserved.

  1. PPL2ab neurons restore sexual responses in aged Drosophila males through dopamine.

    PubMed

    Kuo, Shu-Yun; Wu, Chia-Lin; Hsieh, Min-Yen; Lin, Chen-Ta; Wen, Rong-Kun; Chen, Lien-Cheng; Chen, Yu-Hui; Yu, Yhu-Wei; Wang, Horng-Dar; Su, Yi-Ju; Lin, Chun-Ju; Yang, Cian-Yi; Guan, Hsien-Yu; Wang, Pei-Yu; Lan, Tsuo-Hung; Fu, Tsai-Feng

    2015-06-30

    Male sexual desire typically declines with ageing. However, our understanding of the neurobiological basis for this phenomenon is limited by our knowledge of the brain circuitry and neuronal pathways controlling male sexual desire. A number of studies across species suggest that dopamine (DA) affects sexual desire. Here we use genetic tools and behavioural assays to identify a novel subset of DA neurons that regulate age-associated male courtship activity in Drosophila. We find that increasing DA levels in a subset of cells in the PPL2ab neuronal cluster is necessary and sufficient for increased sustained courtship in both young and aged male flies. Our results indicate that preventing the age-related decline in DA levels in PPL2ab neurons alleviates diminished courtship behaviours in male Drosophila. These results may provide the foundation for deciphering the circuitry involved in sexual motivation in the male Drosophila brain.

  2. Aging Enables Ca2+ Overload and Apoptosis Induced by Amyloid-β Oligomers in Rat Hippocampal Neurons: Neuroprotection by Non-Steroidal Anti-Inflammatory Drugs and R-Flurbiprofen in Aging Neurons.

    PubMed

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

    2016-07-22

    The most important risk factor for Alzheimer's disease (AD) is aging. Neurotoxicity in AD has been linked to dyshomeostasis of intracellular Ca2+ induced by small aggregates of the amyloid-β peptide 1-42 (Aβ42 oligomers). However, how aging influences susceptibility to neurotoxicity induced by Aβ42 oligomers is unknown. In this study, we used long-term cultures of rat hippocampal neurons, a model of neuronal in vitro aging, to investigate the contribution of aging to Ca2+ dishomeostasis and neuron cell death induced by Aβ42 oligomers. In addition, we tested whether non-steroidal anti-inflammatory drugs (NSAIDs) and R-flurbiprofen prevent apoptosis acting on subcellular Ca2+ in aged neurons. We found that Aβ42 oligomers have no effect on young hippocampal neurons cultured for 2 days in vitro (2 DIV). However, they promoted apoptosis modestly in mature neurons (8 DIV) and these effects increased dramatically after 13 DIV, when neurons display many hallmarks of in vivo aging. Consistently, cytosolic and mitochondrial Ca2+ responses induced by Aβ42 oligomers increased dramatically with culture age. At low concentrations, NSAIDs and the enantiomer R-flurbiprofen lacking anti-inflammatory activity prevent Ca2+ overload and neuron cell death induced by Aβ42 oligomers in aged neurons. However, at high concentrations R-flurbiprofen induces apoptosis. Thus, Aβ42 oligomers promote Ca2+ overload and neuron cell death only in aged rat hippocampal neurons. These effects are prevented by low concentrations of NSAIDs and R-flurbiprofen acting on mitochondrial Ca2+ overload.

  3. Reduced N-Type Ca2+ Channels in Atrioventricular Ganglion Neurons Are Involved in Ventricular Arrhythmogenesis.

    PubMed

    Zhang, Dongze; Tu, Huiyin; Cao, Liang; Zheng, Hong; Muelleman, Robert L; Wadman, Michael C; Li, Yu-Long

    2018-01-15

    Attenuated cardiac vagal activity is associated with ventricular arrhythmogenesis and related mortality in patients with chronic heart failure. Our recent study has shown that expression of N-type Ca 2+ channel α-subunits (Ca v 2.2-α) and N-type Ca 2+ currents are reduced in intracardiac ganglion neurons from rats with chronic heart failure. Rat intracardiac ganglia are divided into the atrioventricular ganglion (AVG) and sinoatrial ganglion. Ventricular myocardium receives projection of neuronal terminals only from the AVG. In this study we tested whether a decrease in N-type Ca 2+ channels in AVG neurons contributes to ventricular arrhythmogenesis. Lentiviral Ca v 2.2-α shRNA (2 μL, 2×10 7  pfu/mL) or scrambled shRNA was in vivo transfected into rat AVG neurons. Nontransfected sham rats served as controls. Using real-time single-cell polymerase chain reaction and reverse-phase protein array, we found that in vivo transfection of Ca v 2.2-α shRNA decreased expression of Ca v 2.2-α mRNA and protein in rat AVG neurons. Whole-cell patch-clamp data showed that Ca v 2.2-α shRNA reduced N-type Ca 2+ currents and cell excitability in AVG neurons. The data from telemetry electrocardiographic recording demonstrated that 83% (5 out of 6) of conscious rats with Ca v 2.2-α shRNA transfection had premature ventricular contractions ( P <0.05 versus 0% of nontransfected sham rats or scrambled shRNA-transfected rats). Additionally, an index of susceptibility to ventricular arrhythmias, inducibility of ventricular arrhythmias evoked by programmed electrical stimulation, was higher in rats with Ca v 2.2-α shRNA transfection compared with nontransfected sham rats and scrambled shRNA-transfected rats. A decrease in N-type Ca 2+ channels in AVG neurons attenuates vagal control of ventricular myocardium, thereby initiating ventricular arrhythmias. © 2018 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

  4. Dual-energy precursor and nuclear erythroid-related factor 2 activator treatment additively improve redox glutathione levels and neuron survival in aging and Alzheimer mouse neurons upstream of reactive oxygen species.

    PubMed

    Ghosh, Debolina; LeVault, Kelsey R; Brewer, Gregory J

    2014-01-01

    To determine whether glutathione (GSH) loss or increased reactive oxygen species (ROS) are more important to neuron loss, aging, and Alzheimer's disease (AD), we stressed or boosted GSH levels in neurons isolated from aging 3xTg-AD neurons compared with those from age-matched nontransgenic (non-Tg) neurons. Here, using titrating with buthionine sulfoximine, an inhibitor of γ-glutamyl cysteine synthetase (GCL), we observed that GSH depletion increased neuronal death of 3xTg-AD cultured neurons at increasing rates across the age span, whereas non-Tg neurons were resistant to GSH depletion until old age. Remarkably, the rate of neuron loss with ROS did not increase in old age and was the same for both genotypes, which indicates that cognitive deficits in the AD model were not caused by ROS. Therefore, we targeted for neuroprotection activation of the redox sensitive transcription factor, nuclear erythroid-related factor 2 (Nrf2) by 18 alpha glycyrrhetinic acid to stimulate GSH synthesis through GCL. This balanced stimulation of a number of redox enzymes restored the lower levels of Nrf2 and GCL seen in 3xTg-AD neurons compared with those of non-Tg neurons and promoted translocation of Nrf2 to the nucleus. By combining the Nrf2 activator together with the NADH precursor, nicotinamide, we increased neuron survival against amyloid beta stress in an additive manner. These stress tests and neuroprotective treatments suggest that the redox environment is more important for neuron survival than ROS. The dual neuroprotective treatment with nicotinamide and an Nrf2 inducer indicates that these age-related and AD-related changes are reversible. Copyright © 2014 Elsevier Inc. All rights reserved.

  5. Acute and Chronic Noradrenergic Effects on Cortical Excitability in Healthy Humans

    PubMed Central

    Kuo, Hsiao-I; Paulus, Walter; Batsikadze, Giorgi; Jamil, Asif; Kuo, Min-Fang

    2017-01-01

    Abstract Background Noradrenaline is a major neuromodulator in the central nervous system, and it is involved in the pathophysiology of diverse neuropsychiatric diseases. Previous transcranial magnetic stimulation studies suggested that acute application of selective noradrenaline reuptake inhibitors enhances cortical excitability in the human brain. However, other, such like clinical effects, usually require prolonged noradrenaline reuptake inhibitor treatment, which might go along with different physiological effects. Methods The purpose of this study was to investigate the acute and chronic effects of the selective noradrenaline reuptake inhibitor reboxetine on cortical excitability in healthy humans in a double-blind, placebo-controlled, randomized crossover study. Sixteen subjects were assessed with different transcranial magnetic stimulation measurements: motor thresholds, input-output curve, short-latency intracortical inhibition and intracortical facilitation, I-wave facilitation, and short-interval afferent inhibition before and after placebo or reboxetine (8 mg) single-dose administration. Afterwards, the same subjects took reboxetine (8 mg/d) consecutively for 21 days. During this period (subjects underwent 2 experimental sessions with identical transcranial magnetic stimulation measures under placebo or reboxetine), transcranial magnetic stimulation measurements were assessed before and after drug intake. Results Both single-dose and chronic administration of reboxetine increased cortical excitability; increased the slope of the input-output curve, intracortical facilitation, and I-wave facilitation; but decreased short-latency intracortical inhibition and short-interval afferent inhibition. Moreover, chronic reboxetine showed a larger enhancement of intracortical facilitation and I-wave facilitation compared with single-dose application. Conclusions The results show physiological mechanisms of noradrenergic enhancement possibly underlying the

  6. Mutant LRRK2 Toxicity in Neurons Depends on LRRK2 Levels and Synuclein But Not Kinase Activity or Inclusion Bodies

    PubMed Central

    Skibinski, Gaia; Nakamura, Ken; Cookson, Mark R.

    2014-01-01

    By combining experimental neuron models and mathematical tools, we developed a “systems” approach to deconvolve cellular mechanisms of neurodegeneration underlying the most common known cause of Parkinson's disease (PD), mutations in leucine-rich repeat kinase 2 (LRRK2). Neurons ectopically expressing mutant LRRK2 formed inclusion bodies (IBs), retracted neurites, accumulated synuclein, and died prematurely, recapitulating key features of PD. Degeneration was predicted from the levels of diffuse mutant LRRK2 that each neuron contained, but IB formation was neither necessary nor sufficient for death. Genetic or pharmacological blockade of its kinase activity destabilized LRRK2 and lowered its levels enough to account for the moderate reduction in LRRK2 toxicity that ensued. By contrast, targeting synuclein, including neurons made from PD patient-derived induced pluripotent cells, dramatically reduced LRRK2-dependent neurodegeneration and LRRK2 levels. These findings suggest that LRRK2 levels are more important than kinase activity per se in predicting toxicity and implicate synuclein as a major mediator of LRRK2-induced neurodegeneration. PMID:24403142

  7. 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. Copyright © 2013 Elsevier B.V. All rights reserved.

  8. Deletion of the Kv2.1 delayed rectifier potassium channel leads to neuronal and behavioral hyperexcitability

    PubMed Central

    Speca, David J.; Ogata, Genki; Mandikian, Danielle; Bishop, Hannah I.; Wiler, Steve W.; Eum, Kenneth; Wenzel, H. Jürgen; Doisy, Emily T.; Matt, Lucas; Campi, Katharine L.; Golub, Mari S.; Nerbonne, Jeanne M.; Hell, Johannes W.; Trainor, Brian C.; Sack, Jon T.; Schwartzkroin, Philip A.; Trimmer, James S.

    2014-01-01

    The Kv2.1 delayed rectifier potassium channel exhibits high-level expression in both principal and inhibitory neurons throughout the central nervous system, including prominent expression in hippocampal neurons. Studies of in vitro preparations suggest that Kv2.1 is a key yet conditional regulator of intrinsic neuronal excitability, mediated by changes in Kv2.1 expression, localization and function via activity-dependent regulation of Kv2.1 phosphorylation. Here we identify neurological and behavioral deficits in mutant (Kv2.1−/−) mice lacking this channel. Kv2.1−/− mice have grossly normal characteristics. No impairment in vision or motor coordination was apparent, although Kv2.1−/− mice exhibit reduced body weight. The anatomic structure and expression of related Kv channels in the brains of Kv2.1−/− mice appears unchanged. Delayed rectifier potassium current is diminished in hippocampal neurons cultured from Kv2.1−/− animals. Field recordings from hippocampal slices of Kv2.1−/− mice reveal hyperexcitability in response to the convulsant bicuculline, and epileptiform activity in response to stimulation. In Kv2.1−/− mice, long-term potentiation at the Schaffer collateral – CA1 synapse is decreased. Kv2.1−/− mice are strikingly hyperactive, and exhibit defects in spatial learning, failing to improve performance in a Morris Water Maze task. Kv2.1−/− mice are hypersensitive to the effects of the convulsants flurothyl and pilocarpine, consistent with a role for Kv2.1 as a conditional suppressor of neuronal activity. Although not prone to spontaneous seizures, Kv2.1−/− mice exhibit accelerated seizure progression. Together, these findings suggest homeostatic suppression of elevated neuronal activity by Kv2.1 plays a central role in regulating neuronal network function. PMID:24494598

  9. Chronic treatment with prazosin or duloxetine lessens concurrent anxiety-like behavior and alcohol intake: evidence of disrupted noradrenergic signaling in anxiety-related alcohol use

    PubMed Central

    Skelly, Mary J; Weiner, Jeff L

    2014-01-01

    Background Alcohol use disorders have been linked to increased anxiety, and enhanced central noradrenergic signaling may partly explain this relationship. Pharmacological interventions believed to reduce the excitatory effects of norepinephrine have proven effective in attenuating ethanol intake in alcoholics as well as in rodent models of ethanol dependence. However, most preclinical investigations into the effectiveness of these drugs in decreasing ethanol intake have been limited to acute observations, and none have concurrently assessed their anxiolytic effects. The purpose of these studies was to examine the long-term effectiveness of pharmacological interventions presumed to decrease norepinephrine signaling on concomitant ethanol self-administration and anxiety-like behavior in adult rats with relatively high levels of antecedent anxiety-like behavior. Methods Adult male Long-Evans rats self-administered ethanol on an intermittent access schedule for eight to ten weeks prior to being implanted with osmotic minipumps containing either an a1-adrenoreceptor antagonist (prazosin, 1.5 mg/kg/day), a β1/2-adrenoreceptor antagonist (propranolol, 2.5 mg/kg/day), a serotonin/norepinephrine reuptake inhibitor (duloxetine, 1.5 mg/kg/day) or vehicle (10% dimethyl sulfoxide). These drugs were continuously delivered across four weeks, during which animals continued to have intermittent access to ethanol. Anxiety-like behavior was assessed on the elevated plus maze before treatment and again near the end of the drug delivery period. Results Our results indicate that chronic treatment with a low dose of prazosin or duloxetine significantly decreases ethanol self-administration (P < 0.05). Furthermore, this decrease in drinking is accompanied by significant reductions in the expression of anxiety-like behavior (P < 0.05). Conclusions These findings suggest that chronic treatment with putative inhibitors of central noradrenergic signaling may attenuate ethanol intake via a

  10. Chronic treatment with prazosin or duloxetine lessens concurrent anxiety-like behavior and alcohol intake: evidence of disrupted noradrenergic signaling in anxiety-related alcohol use.

    PubMed

    Skelly, Mary J; Weiner, Jeff L

    2014-07-01

    Alcohol use disorders have been linked to increased anxiety, and enhanced central noradrenergic signaling may partly explain this relationship. Pharmacological interventions believed to reduce the excitatory effects of norepinephrine have proven effective in attenuating ethanol intake in alcoholics as well as in rodent models of ethanol dependence. However, most preclinical investigations into the effectiveness of these drugs in decreasing ethanol intake have been limited to acute observations, and none have concurrently assessed their anxiolytic effects. The purpose of these studies was to examine the long-term effectiveness of pharmacological interventions presumed to decrease norepinephrine signaling on concomitant ethanol self-administration and anxiety-like behavior in adult rats with relatively high levels of antecedent anxiety-like behavior. Adult male Long-Evans rats self-administered ethanol on an intermittent access schedule for eight to ten weeks prior to being implanted with osmotic minipumps containing either an a1-adrenoreceptor antagonist (prazosin, 1.5 mg/kg/day), a β1/2-adrenoreceptor antagonist (propranolol, 2.5 mg/kg/day), a serotonin/norepinephrine reuptake inhibitor (duloxetine, 1.5 mg/kg/day) or vehicle (10% dimethyl sulfoxide). These drugs were continuously delivered across four weeks, during which animals continued to have intermittent access to ethanol. Anxiety-like behavior was assessed on the elevated plus maze before treatment and again near the end of the drug delivery period. Our results indicate that chronic treatment with a low dose of prazosin or duloxetine significantly decreases ethanol self-administration (P < 0.05). Furthermore, this decrease in drinking is accompanied by significant reductions in the expression of anxiety-like behavior (P < 0.05). These findings suggest that chronic treatment with putative inhibitors of central noradrenergic signaling may attenuate ethanol intake via a reduction in anxiety-like behavior.

  11. KCa2 channels activation prevents [Ca2+]i deregulation and reduces neuronal death following glutamate toxicity and cerebral ischemia

    PubMed Central

    Dolga, A M; Terpolilli, N; Kepura, F; Nijholt, I M; Knaus, H-G; D'Orsi, B; Prehn, J H M; Eisel, U L M; Plant, T; Plesnila, N; Culmsee, C

    2011-01-01

    Exacerbated activation of glutamate receptor-coupled calcium channels and subsequent increase in intracellular calcium ([Ca2+]i) are established hallmarks of neuronal cell death in acute and chronic neurological diseases. Here we show that pathological [Ca2+]i deregulation occurring after glutamate receptor stimulation is effectively modulated by small conductance calcium-activated potassium (KCa2) channels. We found that neuronal excitotoxicity was associated with a rapid downregulation of KCa2.2 channels within 3 h after the onset of glutamate exposure. Activation of KCa2 channels preserved KCa2 expression and significantly reduced pathological increases in [Ca2+]i providing robust neuroprotection in vitro and in vivo. These data suggest a critical role for KCa2 channels in excitotoxic neuronal cell death and propose their activation as potential therapeutic strategy for the treatment of acute and chronic neurodegenerative disorders. PMID:21509037

  12. KCa2 channels activation prevents [Ca2+]i deregulation and reduces neuronal death following glutamate toxicity and cerebral ischemia.

    PubMed

    Dolga, A M; Terpolilli, N; Kepura, F; Nijholt, I M; Knaus, H-G; D'Orsi, B; Prehn, J H M; Eisel, U L M; Plant, T; Plesnila, N; Culmsee, C

    2011-04-21

    Exacerbated activation of glutamate receptor-coupled calcium channels and subsequent increase in intracellular calcium ([Ca2+]i) are established hallmarks of neuronal cell death in acute and chronic neurological diseases. Here we show that pathological [Ca2+]i deregulation occurring after glutamate receptor stimulation is effectively modulated by small conductance calcium-activated potassium (KCa2) channels. We found that neuronal excitotoxicity was associated with a rapid downregulation of KCa2.2 channels within 3 h after the onset of glutamate exposure. Activation of KCa2 channels preserved KCa2 expression and significantly reduced pathological increases in [Ca2+]i providing robust neuroprotection in vitro and in vivo. These data suggest a critical role for KCa2 channels in excitotoxic neuronal cell death and propose their activation as potential therapeutic strategy for the treatment of acute and chronic neurodegenerative disorders.

  13. Frontotemporal dementia: evidence for impairment of ascending serotoninergic but not noradrenergic innervation. Immunocytochemical and quantitative study using a graph method.

    PubMed

    Yang, Y; Schmitt, H P

    2001-03-01

    A graph method was employed to analyze the spatial neuronal patterns of nuclear grays of the pontine tegmentum with ascending aminergic projections to the forebrain in 12 cases of frontotemporal dementia (FTD). The nuclear grays examined were the nucleus centralis superior (NCS), a part of the nucleus raphae dorsalis (NRD), and the locus coeruleus (LC). The results were compared with 30 cases of Alzheimer's disease (AD) and 35 non-demented controls. In addition to the graph evaluations, neuronal cytoplasmic inclusion bodies were stained by silver impregnation and ubiquitin (Ub) and tau immunohistochemistry. The FTD cases showed a significant, 40%, decline in number of neurons in the NCS and NRD, while the LC was spared. The magnitude of neuronal loss matched that of AD where, by contrast, the LC was also severely changed. Amyloid deposition and Alzheimer neurofibrillary tangles occurred in the aminergic nuclei almost exclusively in AD and, to a minor extent, in some aged controls. No cytoplasmic inclusion bodies were found in the aminergic nuclei of the FTD cases. However, 6 cases had Ub-positive but tau-negative neuronal inclusions in the hippocampal dentate fascia and in layer 2 of the prefrontal isocortex, and 3 showed clinical and histological signs of motor neuron disease. Our results suggest that the serotoninergic raphe nuclei with ascending projections to the forebrain, but not the LC, become directly or indirectly involved in frontotemporal dementia both with and without motor neuron disease.

  14. Reciprocal regulation between taurine and glutamate response via Ca2+- dependent pathways in retinal third-order neurons

    PubMed Central

    2010-01-01

    Although taurine and glutamate are the most abundant amino acids conducting neural signals in the central nervous system, the communication between these two neurotransmitters is largely unknown. This study explores the interaction of taurine and glutamate in the retinal third-order neurons. Using specific antibodies, both taurine and taurine transporters were localized in photoreceptors and Off-bipolar cells, glutamatergic neurons in retinas. It is possible that Off-bipolar cells release juxtaposed glutamate and taurine to activate the third-order neurons in retina. The interaction of taurine and glutamate was studied in acutely dissociated third-order neurons in whole-cell patch-clamp recording and Ca2+ imaging. We find that taurine effectively reduces glutamate-induced Ca2+ influx via ionotropic glutamate receptors and voltage-dependent Ca2+ channels in the neurons, and the effect of taurine was selectively inhibited by strychnine and picrotoxin, but not GABA receptor antagonists, although GABA receptors are present in the neurons. A CaMKII inhibitor partially reversed the effect of taurine, suggesting that a Ca2+/calmodulin-dependent pathway is involved in taurine regulation. On the other hand, a rapid influx of Ca2+ through ionotropic glutamate receptors could inhibit the amplitude and kinetics of taurine-elicited currents in the third-order neurons, which could be controlled with intracellular application of BAPTA a fast Ca2+ chelator. This study indicates that taurine is a potential neuromodulator in glutamate transmission. The reciprocal inhibition between taurine and glutamate in the postsynaptic neurons contributes to computation of visual signals in the retinal neurons. PMID:20804625

  15. Ebf2 is required for development of dopamine neurons in the midbrain periaqueductal gray matter of mouse.

    PubMed

    Yang, Qiaoqiao; Liu, Shuxi; Yin, Min; Yin, Yanqing; Zhou, Guomin; Zhou, Jiawei

    2015-11-01

    Dopaminergic (DA) neurons in the midbrain ventral periaqueductal gray matter (PAG) play critical roles in various physiological and pathophysiological processes including sleep-wake rhyme, antinociception, and drug addiction. However, the molecular mechanisms underlying their development are poorly understood. Here, we showed that PAG DA neurons arose as early as E15.5 in mouse embryos. During the prenatal period, the majority of PAG DA neurons was distributed in the intermediate and caudal regions of the PAG. In the postnatal brain, ∼50% of PAG DA neurons were preferentially located in the caudal portion of the PAG. Moreover, transcription factor early B-cell factor 2 (Ebf2) was transiently expressed in a subset of DA neurons in embryonic ventral mesencephalon. Functional analysis revealed that loss of Ebf2 in vivo caused a marked reduction in the number of DA neurons in the midbrain PAG but not in the substantia nigra and ventral tegmental area. Thus, Ebf2 is identified as a novel and important regulator selectively required for midbrain PAG DA neuron development. © 2015 Wiley Periodicals, Inc.

  16. Epilepsy-associated gene Nedd4-2 mediates neuronal activity and seizure susceptibility through AMPA receptors.

    PubMed

    Zhu, Jiuhe; Lee, Kwan Young; Jewett, Kathryn A; Man, Heng-Ye; Chung, Hee Jung; Tsai, Nien-Pei

    2017-02-01

    The neural precursor cell expressed developmentally down-regulated gene 4-2, Nedd4-2, is an epilepsy-associated gene with at least three missense mutations identified in epileptic patients. Nedd4-2 encodes a ubiquitin E3 ligase that has high affinity toward binding and ubiquitinating membrane proteins. It is currently unknown how Nedd4-2 mediates neuronal circuit activity and how its dysfunction leads to seizures or epilepsies. In this study, we provide evidence to show that Nedd4-2 mediates neuronal activity and seizure susceptibility through ubiquitination of GluA1 subunit of the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor, (AMPAR). Using a mouse model, termed Nedd4-2andi, in which one of the major forms of Nedd4-2 in the brain is selectively deficient, we found that the spontaneous neuronal activity in Nedd4-2andi cortical neuron cultures, measured by a multiunit extracellular electrophysiology system, was basally elevated, less responsive to AMPAR activation, and much more sensitive to AMPAR blockade when compared with wild-type cultures. When performing kainic acid-induced seizures in vivo, we showed that elevated seizure susceptibility in Nedd4-2andi mice was normalized when GluA1 is genetically reduced. Furthermore, when studying epilepsy-associated missense mutations of Nedd4-2, we found that all three mutations disrupt the ubiquitination of GluA1 and fail to reduce surface GluA1 and spontaneous neuronal activity when compared with wild-type Nedd4-2. Collectively, our data suggest that impaired GluA1 ubiquitination contributes to Nedd4-2-dependent neuronal hyperactivity and seizures. Our findings provide critical information to the future development of therapeutic strategies for patients who carry mutations of Nedd4-2.

  17. A New Regulatory Mechanism for Kv7.2 Protein During Neuropathy: Enhanced Transport from the Soma to Axonal Terminals of Injured Sensory Neurons.

    PubMed

    Cisneros, Elsa; Roza, Carolina; Jackson, Nieka; López-García, José Antonio

    2015-01-01

    Kv7.2 channel expression has been reported to decrease in dorsal root ganglia (DRG) following the induction of a peripheral neuropathy while other experiments show that Kv7.2 accumulates in peripheral neuromas. The mechanisms underlying these novel expression patterns are poorly understood. Here we use immunofluorescence methods to analyze Kv7.2 protein expression changes in sensory neurons following peripheral axotomy and the potential role of axonal transport. Results indicate that DRG neurons express Kv7.2 in ~16% of neurons and that this number decreases by about 65% after axotomy. Damaged neurons were identified in DRG by application of the tracer Fluoro-ruby at the site of injury during surgery. Reduction of Kv7.2 expression was particularly strong in damaged neurons although some loss was also found in putative uninjured neurons. In parallel to the decrease in the soma of axotomized sensory neurons, Kv7.2 accumulated at neuromatose fiber endings. Blockade of axonal transport with either vinblastine (VLB) or colchicine (COL) abolished Kv7.2 redistribution in neuropathic animals. Channel distribution rearrangements did not occur following induction of inflammation in the hind paw. Behavioral tests indicate that protein rearrangements within sensory afferents are essential to the development of allodynia under neuropathic conditions. These results suggest that axotomy enhances axonal transport in injured sensory neurons, leading to a decrease of somatic expression of Kv7.2 protein and a concomitant accumulation in damaged fiber endings. Localized changes in channel expression patterns under pathological conditions may create novel opportunities for Kv7.2 channel openers to act as analgesics.

  18. Noradrenergic alpha-2 receptor modulators in the ventral bed nucleus of the stria terminalis: effects on anxiety behavior in postpartum and virgin female rats.

    PubMed

    Smith, Carl D; Piasecki, Christopher C; Weera, Marcus; Olszewicz, Joshua; Lonstein, Joseph S

    2013-08-01

    Emotional hyperreactivity can inhibit maternal responsiveness in female rats and other animals. Maternal behavior in postpartum rats is disrupted by increasing norepinephrine release in the ventral bed nucleus of the stria terminalis (BSTv) with the α2-autoreceptor antagonist, yohimbine, or the more selective α2-autoreceptor antagonist, idazoxan (Smith et al., 2012). Because high noradrenergic activity in the BSTv can also increase anxiety-related behaviors, increased anxiety may underlie the disrupted mothering of dams given yohimbine or idazoxan. To assess this possibility, anxiety-related behaviors in an elevated plus maze were assessed in postpartum rats after administration of yohimbine or idazoxan. It was further assessed if the α2-autoreceptor agonist clonidine (which decreases norepinephrine release) would, conversely, reduce dams' anxiety. Groups of diestrous virgins were also examined. It was found that peripheral or intra-BSTv yohimbine did increase anxiety-related behavior in postpartum females. However, BSTv infusion of idazoxan did not reproduce yohimbine's anxiogenic effects and anxiety was not reduced by peripheral or intra-BSTv clonidine. Because yohimbine is a weak 5HT1A receptor agonist, other groups of females received BSTv infusion of the 5HT1A receptor agonist 8OH-DPAT, but it did not alter their anxiety-related behavior. Lastly, levels of norepinephrine and serotonin in tissue punches from the BSTv did not differ between postpartum and diestrous rats, but serotonin turnover was lower in mothers. These results suggest that the impaired maternal behavior after BSTv infusion of yohimbine or idazoxan cannot both be readily explained by an increase in dams' anxiety, and that BSTv α2-autoreceptor modulation alone has little influence on anxiety-related behaviors in postpartum or diestrous rats.

  19. NeuronMetrics: Software for Semi-Automated Processing of Cultured-Neuron Images

    PubMed Central

    Narro, Martha L.; Yang, Fan; Kraft, Robert; Wenk, Carola; Efrat, Alon; Restifo, Linda L.

    2007-01-01

    Using primary cell culture to screen for changes in neuronal morphology requires specialized analysis software. We developed NeuronMetrics™ for semi-automated, quantitative analysis of two-dimensional (2D) images of fluorescently labeled cultured neurons. It skeletonizes the neuron image using two complementary image-processing techniques, capturing fine terminal neurites with high fidelity. An algorithm was devised to span wide gaps in the skeleton. NeuronMetrics uses a novel strategy based on geometric features called faces to extract a branch-number estimate from complex arbors with numerous neurite-to-neurite contacts, without creating a precise, contact-free representation of the neurite arbor. It estimates total neurite length, branch number, primary neurite number, territory (the area of the convex polygon bounding the skeleton and cell body), and Polarity Index (a measure of neuronal polarity). These parameters provide fundamental information about the size and shape of neurite arbors, which are critical factors for neuronal function. NeuronMetrics streamlines optional manual tasks such as removing noise, isolating the largest primary neurite, and correcting length for self-fasciculating neurites. Numeric data are output in a single text file, readily imported into other applications for further analysis. Written as modules for ImageJ, NeuronMetrics provides practical analysis tools that are easy to use and support batch processing. Depending on the need for manual intervention, processing time for a batch of ~60 2D images is 1.0–2.5 hours, from a folder of images to a table of numeric data. NeuronMetrics’ output accelerates the quantitative detection of mutations and chemical compounds that alter neurite morphology in vitro, and will contribute to the use of cultured neurons for drug discovery. PMID:17270152

  20. Neuronal network imaging in acute slices using Ca2+ sensitive bioluminescent reporter.

    PubMed

    Tricoire, Ludovic; Lambolez, Bertrand

    2014-01-01

    Genetically encoded indicators are valuable tools to study intracellular signaling cascades in real time using fluorescent or bioluminescent imaging techniques. Imaging of Ca(2+) indicators is widely used to record transient intracellular Ca(2+) increases associated with bioelectrical activity. The natural bioluminescent Ca(2+) sensor aequorin has been historically the first Ca(2+) indicator used to address biological questions. Aequorin imaging offers several advantages over fluorescent reporters: it is virtually devoid of background signal; it does not require light excitation and interferes little with intracellular processes. Genetically encoded sensors such as aequorin are commonly used in dissociated cultured cells; however it becomes more challenging to express them in differentiated intact specimen such as brain tissue. Here we describe a method to express a GFP-aequorin (GA) fusion protein in pyramidal cells of neocortical acute slices using recombinant Sindbis virus. This technique allows expressing GA in several hundreds of neurons on the same slice and to perform the bioluminescence recording of Ca(2+) transients in single neurons or multiple neurons simultaneously.

  1. A high-threshold heat-activated channel in cultured rat dorsal root ganglion neurons resembles TRPV2 and is blocked by gadolinium.

    PubMed

    Leffler, Andreas; Linte, Ramona Madalina; Nau, Carla; Reeh, Peter; Babes, Alexandru

    2007-07-01

    Heat-activated ion channels from the vanilloid-type TRP group (TRPV1-4) seem to be central for heat-sensitivity of nociceptive sensory neurons. Displaying a high-threshold (> 52 degrees C) for activation, TRPV2 was proposed to act as a sensor for intense noxious heat in mammalian sensory neurons. However, although TRPV2 is expressed in a distinct population of thinly myelinated primary afferents, a widespread expression in a variety of neuronal and non-neuronal tissues suggests a more diverse physiological role of TRPV2. In its role as a heat-sensor, TRPV2 has not been thoroughly characterized in terms of biophysical and pharmacological properties. In the present study, we demonstrate that the features of heterologously expressed rat TRPV2 closely resemble those of high-threshold heat-evoked currents in medium- and large-sized capsaicin-insensitive rat dorsal root ganglion (DRG) neurons. Both in TRPV2-expressing human embryonic kidney (HEK)293t cells and in DRGs, high-threshold heat-currents were sensitized by repeated activation and by the TRPV1-3 agonist, 2-aminoethoxydiphenyl borate (2-APB). In addition to a previously described block by ruthenium red, we identified the trivalent cations, lanthanum (La(3+)) and gadolinium (Gd(3+)) as potent blockers of TRPV2. Thus, we present a new pharmacological tool to distinguish between heat responses of TRPV2 and the closely related capsaicin-receptor, TRPV1, which is strongly sensitized by trivalent cations. We demonstrate that self-sensitization of heat-evoked currents through TRPV2 does not require extracellular calcium and that TRPV2 can be activated in cell-free membrane patches in the outside-out configuration. Taken together our results provide new evidence for a role of TRPV2 in mediating high-threshold heat responses in a subpopulation of mammalian sensory neurons.

  2. Glucose deprivation stimulates Cu(2+) toxicity in cultured cerebellar granule neurons and Cu(2+)-dependent zinc release.

    PubMed

    Isaev, Nickolay K; Genrikhs, Elisaveta E; Aleksandrova, Olga P; Zelenova, Elena A; Stelmashook, Elena V

    2016-05-27

    Copper chloride (0.01mM, 2h) did not have significant influence on the survival of cerebellar granule neurons (CGNs) incubated in balanced salt solution. However, CuCl2 caused severe neuronal damage by glucose deprivation (GD). The glutamate NMDA-receptors blocker MK-801 partially and antioxidant N-acetyl-l-cysteine (NAC) or Zn(2+) chelator, N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN) almost entirely protected CGNs from this toxic effect. Measurements of intracellular calcium ions using Fluo-4 AM, or zinc ions with FluoZin-3 AM demonstrated that 1 h-exposure to GD induced intensive increase of Fluo-4 but not FluoZin-3 fluorescence in neurons. The supplementation of solution with CuCl2 caused an increase of FluoZin-3, Fluo-4 and CellROX Green (reactive oxygen species probe) fluorescence by GD. The stimulation of Fluo-4 but not FluoZin-3 fluorescence by copper could be prevented partially by MK-801 and as well as CellROX Green fluorescence by NAC at GD. This data imply that during GD copper ions induce intense displacement zinc ions from intracellular stores, in addition free radical production, glutamate release and Ca(2+) overload of CGNs, that causes death of neurons as a result. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  3. Stimulation of GABA-Induced Ca2+ Influx Enhances Maturation of Human Induced Pluripotent Stem Cell-Derived Neurons

    PubMed Central

    Rushton, David J.; Mattis, Virginia B.; Svendsen, Clive N.; Allen, Nicholas D.; Kemp, Paul J.

    2013-01-01

    Optimal use of patient-derived, induced pluripotent stem cells for modeling neuronal diseases is crucially dependent upon the proper physiological maturation of derived neurons. As a strategy to develop defined differentiation protocols that optimize electrophysiological function, we investigated the role of Ca2+ channel regulation by astrocyte conditioned medium in neuronal maturation, using whole-cell patch clamp and Ca2+ imaging. Standard control medium supported basic differentiation of induced pluripotent stem cell-derived neurons, as assayed by the ability to fire simple, single, induced action potentials. In contrast, treatment with astrocyte conditioned medium elicited complex and spontaneous neuronal activity, often with rhythmic and biphasic characteristics. Such augmented spontaneous activity correlated with astrocyte conditioned medium-evoked hyperpolarization and was dependent upon regulated function of L-, N- and R-type Ca2+ channels. The requirement for astrocyte conditioned medium could be substituted by simply supplementing control differentiation medium with high Ca2+ or γ-amino butyric acid (GABA). Importantly, even in the absence of GABA signalling, opening Ca2+ channels directly using Bay K8644 was able to hyperpolarise neurons and enhance excitability, producing fully functional neurons. These data provide mechanistic insight into how secreted astrocyte factors control differentiation and, importantly, suggest that pharmacological modulation of Ca2+ channel function leads to the development of a defined protocol for improved maturation of induced pluripotent stem cell-derived neurons. PMID:24278369

  4. A noninvasive optical approach for assessing chloride extrusion activity of the K-Cl cotransporter KCC2 in neuronal cells.

    PubMed

    Ludwig, Anastasia; Rivera, Claudio; Uvarov, Pavel

    2017-01-31

    Cation-chloride cotransporters (CCCs) are indispensable for maintaining chloride homeostasis in multiple cell types, but K-Cl cotransporter KCC2 is the only CCC member with an exclusively neuronal expression in mammals. KCC2 is critical for rendering fast hyperpolarizing responses of ionotropic γ-aminobutyric acid and glycine receptors in adult neurons, for neuronal migration in the developing central nervous system, and for the formation and maintenance of small dendritic protrusions-dendritic spines. Deficit in KCC2 expression and/or activity is associated with epilepsy and neuropathic pain, and effective strategies are required to search for novel drugs augmenting KCC2 function. We revised current methods to develop a noninvasive optical approach for assessing KCC2 transport activity using a previously characterized genetically encoded chloride sensor. Our protocol directly assesses dynamics of KCC2-mediated chloride efflux and allows measuring genuine KCC2 activity with good spatial and temporal resolution. As a proof of concept, we used this approach to compare transport activities of the two known KCC2 splice isoforms, KCC2a and KCC2b, in mouse neuronal Neuro-2a cells. Our noninvasive optical protocol proved to be efficient for assessment of furosemide-sensitive chloride fluxes. Transport activities of the N-terminal splice isoforms KCC2a and KCC2b obtained by the novel approach matched to those reported previously using standard methods for measuring chloride fluxes.

  5. Loss of MeCP2 disrupts cell autonomous and autocrine BDNF signaling in mouse glutamatergic neurons

    PubMed Central

    Sampathkumar, Charanya; Wu, Yuan-Ju; Vadhvani, Mayur; Trimbuch, Thorsten; Eickholt, Britta; Rosenmund, Christian

    2016-01-01

    Mutations in the MECP2 gene cause the neurodevelopmental disorder Rett syndrome (RTT). Previous studies have shown that altered MeCP2 levels result in aberrant neurite outgrowth and glutamatergic synapse formation. However, causal molecular mechanisms are not well understood since MeCP2 is known to regulate transcription of a wide range of target genes. Here, we describe a key role for a constitutive BDNF feed forward signaling pathway in regulating synaptic response, general growth and differentiation of glutamatergic neurons. Chronic block of TrkB receptors mimics the MeCP2 deficiency in wildtype glutamatergic neurons, while re-expression of BDNF quantitatively rescues MeCP2 deficiency. We show that BDNF acts cell autonomous and autocrine, as wildtype neurons are not capable of rescuing growth deficits in neighboring MeCP2 deficient neurons in vitro and in vivo. These findings are relevant for understanding RTT pathophysiology, wherein wildtype and mutant neurons are intermixed throughout the nervous system. DOI: http://dx.doi.org/10.7554/eLife.19374.001 PMID:27782879

  6. Kv4.2 Mediates Histamine Modulation of Preoptic Neuron Activity and Body Temperature

    PubMed Central

    Sethi, Jasmine; Sanchez-Alavez, Manuel; Tabarean, Iustin V.

    2011-01-01

    Histamine regulates arousal, circadian rhythms, and thermoregulation. Activation of H3 histamine receptors expressed by preoptic GABAergic neurons results in a decrease of their firing rate and hyperthermia. Here we report that an increase in the A-type K+ current in preoptic GABAergic neurons in response to activation of H3 histamine receptors results in decreased firing rate and hyperthermia in mice. The Kv4.2 subunit is required for these actions in spite of the fact that Kv4.2−/− preoptic GABAergic neurons display A-type currents and firing characteristics similar to those of wild-type neurons. This electrical remodeling is achieved by robust upregulation of the expression of the Kv4.1 subunit and of a delayed rectifier current. Dynamic clamp experiments indicate that enhancement of the A-type current by a similar amount to that induced by histamine is sufficient to mimic its robust effect on firing rates. These data indicate a central role played by the Kv4.2 subunit in histamine regulation of body temperature and its interaction with pERK1/2 downstream of the H3 receptor. We also reveal that this pathway provides a mechanism for selective modulation of body temperature at the beginning of the active phase of the circadian cycle. PMID:22220205

  7. Axial level-specific regulation of neuronal development: lessons from PITX2.

    PubMed

    Waite, Mindy R; Martin, Donna M

    2015-02-01

    Transcriptional regulation of gene expression is vital for proper control of proliferation, migration, differentiation, and survival of developing neurons. Pitx2 encodes a homeodomain transcription factor that is highly expressed in the developing and adult mammalian brain. In humans, mutations in PITX2 result in Rieger syndrome, characterized by defects in the development of the eyes, umbilicus, and teeth and variable abnormalities in the brain, including hydrocephalus and cerebellar hypoplasia. Alternative splicing of Pitx2 in the mouse results in three isoforms, Pitx2a, Pitx2b, and Pitx2c, each of which is expressed symmetrically along the left-right axis of the brain throughout development. Here, we review recent evidence for axial and brain region-specific requirements for Pitx2 during neuronal migration and differentiation, highlighting known isoform contributions. © 2014 Wiley Periodicals, Inc.

  8. Effect of knockout of α2δ-1 on action potentials in mouse sensory neurons.

    PubMed

    Margas, Wojciech; Ferron, Laurent; Nieto-Rostro, Manuela; Schwartz, Arnold; Dolphin, Annette C

    2016-08-05

    Gene deletion of the voltage-gated calcium channel auxiliary subunit α2δ-1 has been shown previously to have a cardiovascular phenotype, and a reduction in mechano- and cold sensitivity, coupled with delayed development of neuropathic allodynia. We have also previously shown that dorsal root ganglion (DRG) neuron calcium channel currents were significantly reduced in α2δ-1 knockout mice. To extend our findings in these sensory neurons, we have examined here the properties of action potentials (APs) in DRG neurons from α2δ-1 knockout mice in comparison to their wild-type (WT) littermates, in order to dissect how the calcium channels that are affected by α2δ-1 knockout are involved in setting the duration of individual APs and their firing frequency. Our main findings are that there is reduced Ca(2+) entry on single AP stimulation, particularly in the axon proximal segment, reduced AP duration and reduced firing frequency to a 400 ms stimulation in α2δ-1 knockout neurons, consistent with the expected role of voltage-gated calcium channels in these events. Furthermore, lower intracellular Ca(2+) buffering also resulted in reduced AP duration, and a lower frequency of AP firing in WT neurons, mimicking the effect of α2δ-1 knockout. By contrast, we did not obtain any consistent evidence for the involvement of Ca(2+)-activation of large conductance calcium-activated potassium (BK) and small conductance calcium-activated potassium (SK) channels in these events. In conclusion, the reduced Ca(2+) elevation as a result of single AP stimulation is likely to result from the reduced duration of the AP in α2δ-1 knockout sensory neurons.This article is part of the themed issue 'Evolution brings Ca(2+) and ATP together to control life and death'. © 2016 The Authors.

  9. A synaptic organizing principle for cortical neuronal groups

    PubMed Central

    Perin, Rodrigo; Berger, Thomas K.; Markram, Henry

    2011-01-01

    Neuronal circuitry is often considered a clean slate that can be dynamically and arbitrarily molded by experience. However, when we investigated synaptic connectivity in groups of pyramidal neurons in the neocortex, we found that both connectivity and synaptic weights were surprisingly predictable. Synaptic weights follow very closely the number of connections in a group of neurons, saturating after only 20% of possible connections are formed between neurons in a group. When we examined the network topology of connectivity between neurons, we found that the neurons cluster into small world networks that are not scale-free, with less than 2 degrees of separation. We found a simple clustering rule where connectivity is directly proportional to the number of common neighbors, which accounts for these small world networks and accurately predicts the connection probability between any two neurons. This pyramidal neuron network clusters into multiple groups of a few dozen neurons each. The neurons composing each group are surprisingly distributed, typically more than 100 μm apart, allowing for multiple groups to be interlaced in the same space. In summary, we discovered a synaptic organizing principle that groups neurons in a manner that is common across animals and hence, independent of individual experiences. We speculate that these elementary neuronal groups are prescribed Lego-like building blocks of perception and that acquired memory relies more on combining these elementary assemblies into higher-order constructs. PMID:21383177

  10. The Upregulation of α2δ-1 Subunit Modulates Activity-Dependent Ca2+ Signals in Sensory Neurons

    PubMed Central

    Margas, Wojciech; Cassidy, John S.

    2015-01-01

    As auxiliary subunits of voltage-gated Ca2+ channels, the α2δ proteins modulate membrane trafficking of the channels and their localization to specific presynaptic sites. Following nerve injury, upregulation of the α2δ-1 subunit in sensory dorsal root ganglion neurons contributes to the generation of chronic pain states; however, very little is known about the underlying molecular mechanisms. Here we show that the increased expression of α2δ-1 in rat sensory neurons leads to prolonged Ca2+ responses evoked by membrane depolarization. This mechanism is coupled to CaV2.2 channel-mediated responses, as it is blocked by a ω-conotoxin GVIA application. Once initiated, the prolonged Ca2+ transients are not dependent on extracellular Ca2+ and do not require Ca2+ release from the endoplasmic reticulum. The selective inhibition of mitochondrial Ca2+ uptake demonstrates that α2δ-1-mediated prolonged Ca2+ signals are buffered by mitochondria, preferentially activated by Ca2+ influx through CaV2.2 channels. Thus, by controlling channel abundance at the plasma membrane, the α2δ-1 subunit has a major impact on the organization of depolarization-induced intracellular Ca2+ signaling in dorsal root ganglion neurons. PMID:25878262

  11. Chronic nandrolone decanoate exposure during adolescence affects emotional behavior and monoaminergic neurotransmission in adulthood.

    PubMed

    Rainer, Quentin; Speziali, Simona; Rubino, Tiziana; Dominguez-Lopez, Sergio; Bambico, Francis Rodriguez; Gobbi, Gabriella; Parolaro, Daniela

    2014-08-01

    Nandrolone decanoate, an anabolic androgen steroid (AAS) illicitly used by adult and adolescent athletes to enhance physical performance and body image, induces psychiatric side effects, such as aggression, depression as well as a spectrum of adverse physiological impairments. Since adolescence represents a neurodevelopmental window that is extremely sensitive to the detrimental effects of drug abuse, we investigated the long-term behavioral and neurophysiological consequences of nandrolone abuse during adolescence. Adolescent rats received daily injections of nandrolone decanoate (15 mg/kg, i.m.) for 14 days (PND 40-53). At early adulthood (PND 68), forced swim, sucrose preference, open field and elevated plus maze tests were performed to assess behavioral changes. In vivo electrophysiological recordings were carried out to monitor changes in electrical activity of serotonergic neurons of the dorsal raphe nucleus (DRN) and noradrenergic neurons of the locus coeruleus (LC). Our results show that after early exposure to nandrolone, rats display depression-related behavior, characterized by increased immobility in the forced swim test and reduced sucrose intake in the sucrose preference test. In addition, adult rats presented anxiety-like behavior characterized by decreased time and number of entries in the central zone of the open field and decreased time spent in the open arms of the elevated plus maze. Nandrolone decreased the firing rate of spontaneously active serotonergic neurons in the DRN while increasing the firing rate of noradrenergic neurons in the LC. These results provide evidence that nandrolone decanoate exposure during adolescence alters the emotional profile of animals in adulthood and significantly modifies both serotonergic and noradrenergic neurotransmission. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Glut2-dependent glucose-sensing controls thermoregulation by enhancing the leptin sensitivity of NPY and POMC neurons.

    PubMed

    Mounien, Lourdes; Marty, Nell; Tarussio, David; Metref, Salima; Genoux, David; Preitner, Frédéric; Foretz, Marc; Thorens, Bernard

    2010-06-01

    The physiological contribution of glucose in thermoregulation is not completely established nor whether this control may involve a regulation of the melanocortin pathway. Here, we assessed thermoregulation and leptin sensitivity of hypothalamic arcuate neurons in mice with inactivation of glucose transporter type 2 (Glut2)-dependent glucose sensing. Mice with inactivation of Glut2-dependent glucose sensors are cold intolerant and show increased susceptibility to food deprivation-induced torpor and abnormal hypothermic response to intracerebroventricular administration of 2-deoxy-d-glucose compared to control mice. This is associated with a defect in regulated expression of brown adipose tissue uncoupling protein I and iodothyronine deiodinase II and with a decreased leptin sensitivity of neuropeptide Y (NPY) and proopiomelanocortin (POMC) neurons, as observed during the unfed-to-refed transition or following i.p. leptin injection. Sites of central Glut-2 expression were identified by a genetic tagging approach and revealed that glucose-sensitive neurons were present in the lateral hypothalamus, the dorsal vagal complex, and the basal medulla but not in the arcuate nucleus. NPY and POMC neurons were, however, connected to nerve terminals from Glut2-expressing neurons. Thus, our data suggest that glucose controls thermoregulation and the leptin sensitivity of NPY and POMC neurons through activation of Glut2-dependent glucose-sensing neurons located outside of the arcuate nucleus.

  13. Rescue of neuronal migration deficits in a mouse model of fetal Minamata disease by increasing neuronal Ca2+ spike frequency.

    PubMed

    Fahrion, Jennifer K; Komuro, Yutaro; Li, Ying; Ohno, Nobuhiko; Littner, Yoav; Raoult, Emilie; Galas, Ludovic; Vaudry, David; Komuro, Hitoshi

    2012-03-27

    In the brains of patients with fetal Minamata disease (FMD), which is caused by exposure to methylmercury (MeHg) during development, many neurons are hypoplastic, ectopic, and disoriented, indicating disrupted migration, maturation, and growth. MeHg affects a myriad of signaling molecules, but little is known about which signals are primary targets for MeHg-induced deficits in neuronal development. In this study, using a mouse model of FMD, we examined how MeHg affects the migration of cerebellar granule cells during early postnatal development. The cerebellum is one of the most susceptible brain regions to MeHg exposure, and profound loss of cerebellar granule cells is detected in the brains of patients with FMD. We show that MeHg inhibits granule cell migration by reducing the frequency of somal Ca(2+) spikes through alterations in Ca(2+), cAMP, and insulin-like growth factor 1 (IGF1) signaling. First, MeHg slows the speed of granule cell migration in a dose-dependent manner, independent of the mode of migration. Second, MeHg reduces the frequency of spontaneous Ca(2+) spikes in granule cell somata in a dose-dependent manner. Third, a unique in vivo live-imaging system for cell migration reveals that reducing the inhibitory effects of MeHg on somal Ca(2+) spike frequency by stimulating internal Ca(2+) release and Ca(2+) influxes, inhibiting cAMP activity, or activating IGF1 receptors ameliorates the inhibitory effects of MeHg on granule cell migration. These results suggest that alteration of Ca(2+) spike frequency and Ca(2+), cAMP, and IGF1 signaling could be potential therapeutic targets for infants with MeHg intoxication.

  14. Rescue of neuronal migration deficits in a mouse model of fetal Minamata disease by increasing neuronal Ca2+ spike frequency

    PubMed Central

    Fahrion, Jennifer K.; Ohno, Nobuhiko; Littner, Yoav; Raoult, Emilie; Galas, Ludovic; Vaudry, David; Komuro, Hitoshi

    2012-01-01

    In the brains of patients with fetal Minamata disease (FMD), which is caused by exposure to methylmercury (MeHg) during development, many neurons are hypoplastic, ectopic, and disoriented, indicating disrupted migration, maturation, and growth. MeHg affects a myriad of signaling molecules, but little is known about which signals are primary targets for MeHg-induced deficits in neuronal development. In this study, using a mouse model of FMD, we examined how MeHg affects the migration of cerebellar granule cells during early postnatal development. The cerebellum is one of the most susceptible brain regions to MeHg exposure, and profound loss of cerebellar granule cells is detected in the brains of patients with FMD. We show that MeHg inhibits granule cell migration by reducing the frequency of somal Ca2+ spikes through alterations in Ca2+, cAMP, and insulin-like growth factor 1 (IGF1) signaling. First, MeHg slows the speed of granule cell migration in a dose-dependent manner, independent of the mode of migration. Second, MeHg reduces the frequency of spontaneous Ca2+ spikes in granule cell somata in a dose-dependent manner. Third, a unique in vivo live-imaging system for cell migration reveals that reducing the inhibitory effects of MeHg on somal Ca2+ spike frequency by stimulating internal Ca2+ release and Ca2+ influxes, inhibiting cAMP activity, or activating IGF1 receptors ameliorates the inhibitory effects of MeHg on granule cell migration. These results suggest that alteration of Ca2+ spike frequency and Ca2+, cAMP, and IGF1 signaling could be potential therapeutic targets for infants with MeHg intoxication. PMID:22411806

  15. Angiotensin II potentiates zinc-induced cortical neuronal death by acting on angiotensin II type 2 receptor.

    PubMed

    Park, Mi-Ha; Kim, Ha Na; Lim, Joon Seo; Ahn, Jae-Sung; Koh, Jae-Young

    2013-12-01

    The angiotensin system has several non-vascular functions in the central nervous system. For instance, inhibition of the brain angiotensin system results in a reduction in neuronal death following acute brain injury such as ischemia and intracerebral hemorrhage, even under conditions of constant blood pressure. Since endogenous zinc has been implicated as a key mediator of ischemic neuronal death, we investigated the possibility that the angiotensin system affects the outcome of zinc-triggered neuronal death in cortical cell cultures. Exposure of cortical cultures containing neurons and astrocytes to 300 μM zinc for 15 min induced submaximal death in both types of cells. Interestingly, addition of angiotensin II significantly enhanced the zinc-triggered neuronal death, while leaving astrocytic cell death relatively unchanged. Both type 1 and 2 angiotensin II receptors (AT1R and AT2R, respectively) were expressed in neurons as well as astrocytes. Zinc neurotoxicity was substantially attenuated by PD123319, a specific inhibitor of AT2R, and augmented by CGP42112, a selective activator of AT2R, indicating a critical role for this receptor subtype in the augmentation of neuronal cell death.Because zinc toxicity occurs largely through oxidative stress, the levels of superoxides in zinc-treated neurons were assessed by DCF fluorescence microscopy. Combined treatment with zinc and angiotensin II substantially increased the levels of superoxides in neurons compared to those induced by zinc alone. This increase in oxidative stress by angiotensin II was completely blocked by the addition of PD123319. Finally, since zinc-induced oxidative stress may be caused by induction and/or activation of NADPH oxidase, the activation status of Rac and the level of the NADPH oxidase subunit p67phox were measured. Angiotensin II markedly increased Rac activity and the levels of p67phox in zinc-treated neurons and astrocytes in a PD123319-dependent manner. The present study shows that the

  16. Trafficking of presynaptic AMPA receptors mediating neurotransmitter release: neuronal selectivity and relationships with sensitivity to cyclothiazide.

    PubMed

    Pittaluga, Anna; Feligioni, Marco; Longordo, Fabio; Luccini, Elisa; Raiteri, Maurizio

    2006-03-01

    Postsynaptic glutamate AMPA receptors (AMPARs) can recycle between plasma membrane and intracellular pools. In contrast, trafficking of presynaptic AMPARs has not been investigated. AMPAR surface expression involves interactions between the GluR2 carboxy tail and various proteins including glutamate receptor-interacting protein (GRIP), AMPA receptor-binding protein (ABP), protein interacting with C kinase 1 (PICK1), N-ethyl-maleimide-sensitive fusion protein (NSF). Here, peptides known to selectively block the above interactions were entrapped into synaptosomes to study the effects on the AMPA-evoked release of [3H]noradrenaline ([3H]NA) and [3H]acetylcholine ([3H]ACh) from rat hippocampal and cortical synaptosomes, respectively. Internalization of pep2-SVKI to prevent GluR2-GRIP/ABP/PICK1 interactions potentiated the AMPA-evoked release of [3H]NA but left unmodified that of [3H]ACh. Similar potentiation was caused by pep2-AVKI, the blocker of GluR2-PICK1 interaction. Conversely, a decrease in the AMPA-evoked release of [3H]NA, but not of [3H]ACh, was caused by pep2m, a selective blocker of the GluR2-NSF interaction. In the presence of pep2-SVKI the presynaptic AMPARs on noradrenergic terminals lost sensitivity to cyclothiazide. AMPARs releasing [3H]ACh, but not those releasing [3H]NA, were sensitive to spermine, suggesting that they are GluR2-lacking AMPARs. To conclude: (i) release-regulating presynaptic AMPARs constitutively cycle in isolated nerve terminals; (ii) the process exhibits neuronal selectivity; (iii) AMPAR trafficking and desensitization may be interrelated.

  17. Evaluation of the rotenone-induced activation of the Nrf2 pathway in a neuronal model derived from human induced pluripotent stem cells.

    PubMed

    Zagoura, Dimitra; Canovas-Jorda, David; Pistollato, Francesca; Bremer-Hoffmann, Susanne; Bal-Price, Anna

    2017-06-01

    Human induced pluripotent stem cells (hiPSCs) are considered as a powerful tool for drug and chemical screening and development of new in vitro testing strategies in the field of toxicology, including neurotoxicity evaluation. These cells are able to expand and efficiently differentiate into different types of neuronal and glial cells as well as peripheral neurons. These human cells-based neuronal models serve as test systems for mechanistic studies on different pathways involved in neurotoxicity. One of the well-known mechanisms that are activated by chemically-induced oxidative stress is the Nrf2 signaling pathway. Therefore, in the current study, we evaluated whether Nrf2 signaling machinery is expressed in human induced pluripotent stem cells (hiPSCs)-derived mixed neuronal/glial culture and if so whether it becomes activated by rotenone-induced oxidative stress mediated by complex I inhibition of mitochondrial respiration. Rotenone was found to induce the activation of Nrf2 signaling particularly at the highest tested concentration (100 nM), as shown by Nrf2 nuclear translocation and the up-regulation of the Nrf2-downstream antioxidant enzymes, NQO1 and SRXN1. Interestingly, exposure to rotenone also increased the number of astroglial cells in which Nrf2 activation may play an important role in neuroprotection. Moreover, rotenone caused cell death of dopaminergic neurons since a decreased percentage of tyrosine hydroxylase (TH + ) cells was observed. The obtained results suggest that hiPSC-derived mixed neuronal/glial culture could be a valuable in vitro human model for the establishment of neuronal specific assays in order to link Nrf2 pathway activation (biomarker of oxidative stress) with additional neuronal specific readouts that could be applied to in vitro neurotoxicity evaluation. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  18. A New Regulatory Mechanism for Kv7.2 Protein During Neuropathy: Enhanced Transport from the Soma to Axonal Terminals of Injured Sensory Neurons

    PubMed Central

    Cisneros, Elsa; Roza, Carolina; Jackson, Nieka; López-García, José Antonio

    2015-01-01

    Kv7.2 channel expression has been reported to decrease in dorsal root ganglia (DRG) following the induction of a peripheral neuropathy while other experiments show that Kv7.2 accumulates in peripheral neuromas. The mechanisms underlying these novel expression patterns are poorly understood. Here we use immunofluorescence methods to analyze Kv7.2 protein expression changes in sensory neurons following peripheral axotomy and the potential role of axonal transport. Results indicate that DRG neurons express Kv7.2 in ~16% of neurons and that this number decreases by about 65% after axotomy. Damaged neurons were identified in DRG by application of the tracer Fluoro-ruby at the site of injury during surgery. Reduction of Kv7.2 expression was particularly strong in damaged neurons although some loss was also found in putative uninjured neurons. In parallel to the decrease in the soma of axotomized sensory neurons, Kv7.2 accumulated at neuromatose fiber endings. Blockade of axonal transport with either vinblastine (VLB) or colchicine (COL) abolished Kv7.2 redistribution in neuropathic animals. Channel distribution rearrangements did not occur following induction of inflammation in the hind paw. Behavioral tests indicate that protein rearrangements within sensory afferents are essential to the development of allodynia under neuropathic conditions. These results suggest that axotomy enhances axonal transport in injured sensory neurons, leading to a decrease of somatic expression of Kv7.2 protein and a concomitant accumulation in damaged fiber endings. Localized changes in channel expression patterns under pathological conditions may create novel opportunities for Kv7.2 channel openers to act as analgesics. PMID:26696829

  19. Metabolic reprogramming during neuronal differentiation from aerobic glycolysis to neuronal oxidative phosphorylation.

    PubMed

    Zheng, Xinde; Boyer, Leah; Jin, Mingji; Mertens, Jerome; Kim, Yongsung; Ma, Li; Ma, Li; Hamm, Michael; Gage, Fred H; Hunter, Tony

    2016-06-10

    How metabolism is reprogrammed during neuronal differentiation is unknown. We found that the loss of hexokinase (HK2) and lactate dehydrogenase (LDHA) expression, together with a switch in pyruvate kinase gene splicing from PKM2 to PKM1, marks the transition from aerobic glycolysis in neural progenitor cells (NPC) to neuronal oxidative phosphorylation. The protein levels of c-MYC and N-MYC, transcriptional activators of the HK2 and LDHA genes, decrease dramatically. Constitutive expression of HK2 and LDHA during differentiation leads to neuronal cell death, indicating that the shut-off aerobic glycolysis is essential for neuronal survival. The metabolic regulators PGC-1α and ERRγ increase significantly upon neuronal differentiation to sustain the transcription of metabolic and mitochondrial genes, whose levels are unchanged compared to NPCs, revealing distinct transcriptional regulation of metabolic genes in the proliferation and post-mitotic differentiation states. Mitochondrial mass increases proportionally with neuronal mass growth, indicating an unknown mechanism linking mitochondrial biogenesis to cell size.

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

    PubMed

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

    2013-07-02

    Glucagon-like peptides (GLP-1/GLP-2) are coproduced and highlighted as key modulators to improve glucose homeostasis and insulin sensitivity after bariatric surgery. However, it is unknown if CNS GLP-2 plays any physiological role in the control of glucose homeostasis and insulin sensitivity. We show that mice lacking GLP-2 receptor (GLP-2R) in POMC neurons display glucose intolerance and hepatic insulin resistance. GLP-2R activation in POMC neurons is required for GLP-2 to enhance insulin-mediated suppression of hepatic glucose production (HGP) and gluconeogenesis. GLP-2 directly modulates excitability of POMC neurons in GLP-2R- and PI3K-dependent manners. GLP-2 initiates GLP-2R-p85α interaction and facilitates PI3K-Akt-dependent FoxO1 nuclear exclusion in POMC neurons. Central GLP-2 suppresses basal HGP and enhances insulin sensitivity, which are abolished in POMC-p110α KO mice. Thus, CNS GLP-2 plays a key physiological role in the control of HGP through activating PI3K-dependent modulation of membrane excitability and nuclear transcription of POMC neurons in the brain. Copyright © 2013 Elsevier Inc. All rights reserved.

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

    PubMed Central

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

    2013-01-01

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

  2. L-Dihydroxyphenylserine (L-DOPS): a norepinephrine prodrug.

    PubMed

    Goldstein, David S

    2006-01-01

    L-threo-3,4-dihydroxyphenylserine (L-DOPS, droxydopa) is a synthetic catecholamino acid. When taken orally, L-DOPS is converted to the sympathetic neurotransmitter, norepinephrine (NE), via decarboxylation catalyzed by L-aromatic-amino-acid decarboxylase (LAAAD). Plasma L-DOPS levels peak at about 3 h, followed by a monoexponential decline with a half-time of 2 to 3 h. Plasma levels of NE and of its main neuronal metabolite, dihydroxyphenylglycol (DHPG) peak approximately concurrently but at much lower concentrations. The relatively long half-time for disappearance of L-DOPS from plasma, compared to that of NE, explains their very different attained plasma concentrations. In patients with neurogenic orthostatic hypotension, L-DOPS increases blood pressure and ameliorates orthostatic intolerance. Inhibition of LAAAD, such as by treatment with carbidopa, which does not penetrate the blood-brain barrier, prevents the blood pressure effects of the drug, indicating that L-DOPS increases blood pressure by augmenting NE production outside the brain. Patients with pure autonomic failure (which usually entails loss of sympathetic noradrenergic nerves), and patients with multiple system atrophy (in which noradrenergic innervation remains intact) have similar plasma NE responses to L-DOPS. This suggests mainly non-neuronal production of NE from L-DOPS. L-DOPS is very effective in treatment of deficiency of dopamine-beta-hydroxylase (DBH), the enzyme required for conversion of dopamine to NE in sympathetic nerves. L-DOPS holds promise for treating other much more common conditions involving decreased DBH activity or NE deficiency, such as a variety of syndromes associated with neurogenic orthostatic hypotension.

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

    PubMed

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

    2017-03-20

    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.

  4. Characterization of dopamine D1 and D2 receptor-expressing neurons in the mouse hippocampus.

    PubMed

    Gangarossa, Giuseppe; Longueville, Sophie; De Bundel, Dimitri; Perroy, Julie; Hervé, Denis; Girault, Jean-Antoine; Valjent, Emmanuel

    2012-12-01

    The hippocampal formation is part of an anatomical system critically involved in learning and memory. Increasing evidence suggests that dopamine plays an important role in learning and memory as well as in several forms of synaptic plasticity. However, the precise identification of neuronal populations expressing D1 or D2 dopamine receptors within the hippocampus is still lacking. To clarify this issue, we used BAC transgenic mice expressing enhanced green fluorescent protein (EGFP) under the control of the promoter of dopamine D1 or D2 receptors. In Drd1a-EGFP mice, sparse GFP-expressing neurons were detected among glutamatergic projecting neurons of the granular layer of the dentate gyrus and GABAergic interneurons located in the hilus. A dense immunofluorescence was observed in the outer and medial part of the molecular layer of the dentate gyrus as well as in the inner part of the molecular layer of CA1 corresponding to the terminals of pyramidal neurons of the entorhinal cortex defining the perforant and the temporo-ammonic pathway respectively. Finally, scattered D1 receptor-expressing neurons were also identified as GABAergic interneurons in the CA3/CA1 fields of the hippocampus. In Drd2-EGFP transgenic mice, GFP was exclusively detected in the glutamatergic mossy cells located in the polymorphic layer of the dentate gyrus. This pattern was confirmed in Drd2-Cre mice crossed with NLS-LacZ-Tau(mGFP) :LoxP and RCE:LoxP reporter lines. Our results demonstrate that D1 and D2 receptor-expressing neurons are strictly segregated in the mouse hippocampus. By clarifying the identity of D1 and D2 receptor-expressing neurons in the hippocampus, this study establishes a basis for future investigations aiming at elucidating their roles in the hippocampal network. Copyright © 2012 Wiley Periodicals, Inc.

  5. On the continuous differentiability of inter-spike intervals of synaptically connected cortical spiking neurons in a neuronal network.

    PubMed

    Kumar, Gautam; Kothare, Mayuresh V

    2013-12-01

    We derive conditions for continuous differentiability of inter-spike intervals (ISIs) of spiking neurons with respect to parameters (decision variables) of an external stimulating input current that drives a recurrent network of synaptically connected neurons. The dynamical behavior of individual neurons is represented by a class of discontinuous single-neuron models. We report here that ISIs of neurons in the network are continuously differentiable with respect to decision variables if (1) a continuously differentiable trajectory of the membrane potential exists between consecutive action potentials with respect to time and decision variables and (2) the partial derivative of the membrane potential of spiking neurons with respect to time is not equal to the partial derivative of their firing threshold with respect to time at the time of action potentials. Our theoretical results are supported by showing fulfillment of these conditions for a class of known bidimensional spiking neuron models.

  6. The ROR2 tyrosine kinase receptor regulates dendritic spine morphogenesis in hippocampal neurons.

    PubMed

    Alfaro, Iván E; Varela-Nallar, Lorena; Varas-Godoy, Manuel; Inestrosa, Nibaldo C

    2015-07-01

    Wnt signaling regulates synaptic development and function and contributes to the fine-tuning of the molecular and morphological differentiation of synapses. We have shown previously that Wnt5a activates non-canonical Wnt signaling to stimulate postsynaptic differentiation in excitatory hippocampal neurons promoting the clustering of the postsynaptic scaffold protein PSD-95 and the development of dendritic spines. At least three different kinds of Wnt receptors have been associated with Wnt5a signaling: seven trans-membrane Frizzled receptors and the tyrosine kinase receptors Ryk and ROR2. We report here that ROR2 is distributed in the dendrites of hippocampal neurons in close proximity to synaptic contacts and it is contained in dendritic spine protrusions. We demonstrate that ROR2 is necessary to maintain dendritic spine number and morphological distribution in cultured hippocampal neurons. ROR2 overexpression increased dendritic spine growth without affecting the density of dendritic spine protrusions in a form dependent on its extracellular Wnt binding cysteine rich domain (CRD) and kinase domain. Overexpression of dominant negative ROR2 lacking the extracellular CRD decreased spine density and the proportion of mushroom like spines, while ROR2 lacking the C-terminal and active kinase domains only affected spine morphology. Our results indicate a crucial role of the ROR2 in the formation and maturation of the postsynaptic dendritic spines in hippocampal neurons. Copyright © 2015 Elsevier Inc. All rights reserved.

  7. Inhibition of monocarboxylate transporter 2 in the retrotrapezoid nucleus in rats – a test of the astrocyte-neuron lactate-shuttle hypothesis

    PubMed Central

    Erlichman, J.S.; Hewitt, Amy; Damon, Tracey L.; Hart, Michael; Kurascz, Jennifer; Li, A.; Leiter, J.C.

    2009-01-01

    The astrocyte-neuronal lactate shuttle hypothesis (ANLSH) posits that lactate released from astrocytes into the extracellular space is metabolized by neurons. The lactate released should alter extracellular pH (pHe), and changes in pH in central chemosensory regions of the brainstem stimulate ventilation. Therefore, we assessed the impact of disrupting the lactate shuttle by administering 100 microM α-cyano-4-hydroxy-cinnamate (4-CIN), a dose that blocks the neuronal monocarboxylate transporter (MCT2), but not the astrocytic MCTs (MCT1 and MCT4). Administration of 4-CIN focally in the retrotrapezoid nucleus (RTN), a medullary central chemosensory nucleus, increased ventilation and decreased pHe in intact animals. In medullary brain slices, 4-CIN reduced astrocytic intracellular pH (pHi) slightly, but alkalinized neuronal pHi. Nonetheless, pHi fell significantly in both cell types when they were treated with exogenous lactate, although 100 microM 4-CIN significantly reduced the magnitude of the acidosis in neurons, but not astrocytes. Finally, 4-CIN treatment increased the uptake of a fluorescent 2-deoxy-d-glucose analogue in neurons, but did not alter the uptake rate of this 2-deoxy-d-glucose analogue in astrocytes. These data confirm the existence of an astrocyte to neuron lactate shuttle in intact animals in the RTN, and lactate derived from astrocytes forms part of the central chemosensory stimulus for ventilation in this nucleus. When the lactate shuttle was disrupted by treatment with 4-CIN, neurons increased the uptake of glucose. Thus, neurons seem to metabolize a combination of glucose and lactate (and other substances such as pyruvate) depending, in part, on the availability of each of these particular substrates. PMID:18463242

  8. NDRG2 promoted secreted miR-375 in microvesicles shed from M1 microglia, which induced neuron damage.

    PubMed

    Tang, Li-li; Wu, Yuan-bo; Fang, Chuan-qin; Qu, Ping; Gao, Zong-liang

    2016-01-15

    Microglia microvesicles (MVs) has shown to have significant biological functions under normal conditions. A diversity of miRNAs is involved in neuronal development, survival, function, and plasticity, but the exact functional role of NDRG2 and secreted miR-375 in MVs in neuron damage is poorly understood. We investigated the effect of NDRG2 and secreted miR-375 in MVs shed from M1 microglia on neuron damage. Expression of Nos2, Arg-1, miR-375, syntaxin-1A, NDRG2 and Pdk 1 were evaluated using RT-PCR or western blotting. Cell viability of N2A neuron was quantified by a MTT assay. Microglia can be polarized into different functional phenotypes. Expression of NDRG2 and Nos2 were significantly increased by LPS treatment on N9 cells, whereas treatment with IL-4 dramatically suppressed the expression of NDRG2 and remarkably elevated expression of Arg-1. Besides, MVs shed from LPS-treated N9 microglia significantly inhibited cell viability of N2A neurons and expression of syntaxin-1A, and NDRG2 interference reversed the up-regulated miR-375 in LPS-treated N9 microglia and MVs shed from LPS-treated N9 cells. Furthermore, NDRG2 could modulate miR-375 expression in N9 microglia and MVs. And miR-375 inhibitor remarkably elevated Pdk1 expression in N2A neurons. Finally, miR-375 inhibitor could reverse suppression effect of NDRG2 overexpression on cell viability of N2A neurons and expression of syntaxin-1A. Our results demonstrated that NDRG2 promoted secreted miR-375 in microvesicles shed from M1 microglia, which induced neuron damage. The suppression of NDRG2 and secreted miR-375 in MVs shed from M1 microglia may be potential targets for alleviation of neuron damage. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. Upregulation of T-type Ca2+ channels in long-term diabetes determines increased excitability of a specific type of capsaicin-insensitive DRG neurons.

    PubMed

    Duzhyy, Dmytro E; Viatchenko-Karpinski, Viacheslav Y; Khomula, Eugen V; Voitenko, Nana V; Belan, Pavel V

    2015-05-20

    Previous studies have shown that increased excitability of capsaicin-sensitive DRG neurons and thermal hyperalgesia in rats with short-term (2-4 weeks) streptozotocin-induced diabetes is mediated by upregulation of T-type Ca(2+) current. In longer-term diabetes (after the 8th week) thermal hyperalgesia is changed to hypoalgesia that is accompanied by downregulation of T-type current in capsaicin-sensitive small-sized nociceptors. At the same time pain symptoms of diabetic neuropathy other than thermal persist in STZ-diabetic animals and patients during progression of diabetes into later stages suggesting that other types of DRG neurons may be sensitized and contribute to pain. In this study, we examined functional expression of T-type Ca(2+) channels in capsaicin-insensitive DRG neurons and excitability of these neurons in longer-term diabetic rats and in thermally hypoalgesic diabetic rats. Here we have demonstrated that in STZ-diabetes T-type current was upregulated in capsaicin-insensitive low-pH-sensitive small-sized nociceptive DRG neurons of longer-term diabetic rats and thermally hypoalgesic diabetic rats. This upregulation was not accompanied by significant changes in biophysical properties of T-type channels suggesting that a density of functionally active channels was increased. Sensitivity of T-type current to amiloride (1 mM) and low concentration of Ni(2+) (50 μM) implicates prevalence of Cav3.2 subtype of T-type channels in the capsaicin-insensitive low-pH-sensitive neurons of both naïve and diabetic rats. The upregulation of T-type channels resulted in the increased neuronal excitability of these nociceptive neurons revealed by a lower threshold for action potential initiation, prominent afterdepolarizing potentials and burst firing. Sodium current was not significantly changed in these neurons during long-term diabetes and could not contribute to the diabetes-induced increase of neuronal excitability. Capsaicin-insensitive low-pH-sensitive type

  10. Pharmacological Targeting Of Neuronal Kv7.2/3 Channels: A Focus On Chemotypes And Receptor Sites.

    PubMed

    Miceli, Francesco; Soldovieri, Maria Virginia; Ambrosino, Paolo; Manocchio, Laura; Medoro, Alessandro; Mosca, Ilaria; Taglialatela, Maurizio

    2017-10-12

    The Kv7 (KCNQ) subfamily of voltage-gated potassium channels consists of 5 members (Kv7.1-5) each showing a characteristic tissue distribution and physiological roles. Given their functional heterogeneity, Kv7 channels represent important pharmacological targets for development of new drugs for neuronal, cardiac and metabolic diseases. In the present manuscript, we focus on describing the pharmacological relevance and the potential therapeutic applications of drugs acting on neuronally-expressed Kv7.2/3 channels, placing particular emphasis on the different modulator chemotypes, and highlighting their pharmacodynamic and, whenever possible, pharmacokinetic peculiarities. The present work is based on an in-depth search of the currently available scientific literature, and on our own experience and knowledge in the field of neuronal Kv7 channel pharmacology. Space limitations impeded to describe the full pharmacological potential of Kv7 channels; thus, we have chosen to focus on neuronal channels composed of Kv7.2 and Kv7.3 subunits, and to mainly concentrate on their involvement in epilepsy. An astonishing heterogeneity in the molecular scaffolds exploitable to develop Kv7.2/3 modulators is evident, with important structural/functional peculiarities of distinct compound classes. In the present work we have attempted to show the current status and growing potential of the Kv7 pharmacology field. We anticipate a bright future for the field, and we express our hopes that the efforts herein reviewed will result in an improved treatment of hyperexcitability (or any other) diseases. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  11. Na+,K+-ATPase functionally interacts with the plasma membrane Na+,Ca2+ exchanger to prevent Ca2+ overload and neuronal apoptosis in excitotoxic stress.

    PubMed

    Sibarov, Dmitry A; Bolshakov, Artemiy E; Abushik, Polina A; Krivoi, Igor I; Antonov, Sergei M

    2012-12-01

    Using a fluorescent viability assay, immunocytochemistry, patch-clamp recordings, and Ca(2+) imaging analysis, we report that ouabain, a specific ligand of the Na(+),K(+)-ATPase cardiac glycoside binding site, can prevent glutamate receptor agonist-induced apoptosis in cultured rat cortical neurons. In our model of excitotoxicity, a 240-min exposure to 30 μM N-methyl-d-aspartate (NMDA) or kainate caused apoptosis in ∼50% of neurons. These effects were accompanied by a significant decrease in the number of neurons that were immunopositive for the antiapoptotic peptide Bcl-2. Apoptotic injury was completely prevented when the agonists were applied together with 0.1 or 1 nM ouabain, resulting in a greater survival of neurons, and the percentage of neurons expressing Bcl-2 remained similar to those obtained without agonist treatments. In addition, subnanomolar concentrations of ouabain prevented the increase of spontaneous excitatory postsynaptic current's frequency and the intracellular Ca(2+) overload induced by excitotoxic insults. Loading neurons with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid or inhibition of the plasma membrane Na(+),Ca(2+)-exchanger by 2-(2-(4-(4-nitrobenzyloxy)phenyl)ethyl)isothiourea methanesulfonate (KB-R7943) eliminated ouabain's effects on NMDA- or kainite-evoked enhancement of spontaneous synaptic activity. Our data suggest that during excitotoxic insults ouabain accelerates Ca(2+) extrusion from neurons via the Na(+),Ca(2+) exchanger. Because intracellular Ca(2+) accumulation caused by the activation of glutamate receptors and boosted synaptic activity represents a key factor in triggering neuronal apoptosis, up-regulation of Ca(2+) extrusion abolishes its development. These antiapoptotic effects are independent of Na(+),K(+)-ATPase ion transport function and are initiated by concentrations of ouabain that are within the range of an endogenous analog, suggesting a novel functional role for Na(+),K(+)-ATPase in

  12. Optogenetic Stimulation of Arcuate Nucleus Kiss1 Neurons Reveals a Steroid-Dependent Glutamatergic Input to POMC and AgRP Neurons in Male Mice

    PubMed Central

    Nestor, Casey C; Qiu, Jian; Padilla, Stephanie L.; Zhang, Chunguang; Bosch, Martha A.; Fan, Wei; Aicher, Sue A.; Palmiter, Richard D.

    2016-01-01

    Kisspeptin (Kiss1) neurons are essential for reproduction, but their role in the control of energy balance and other homeostatic functions remains unclear. Proopiomelanocortin (POMC) and agouti-related peptide (AgRP) neurons, located in the arcuate nucleus (ARC) of the hypothalamus, integrate numerous excitatory and inhibitory inputs to ultimately regulate energy homeostasis. Given that POMC and AgRP neurons are contacted by Kiss1 neurons in the ARC (Kiss1ARC) and they express androgen receptors, Kiss1ARC neurons may mediate the orexigenic action of testosterone via POMC and/or AgRP neurons. Quantitative PCR analysis of pooled Kiss1ARC neurons revealed that mRNA levels for Kiss1 and vesicular glutamate transporter 2 were higher in castrated male mice compared with gonad-intact males. Single-cell RT-PCR analysis of yellow fluorescent protein (YFP) ARC neurons harvested from males injected with AAV1-EF1α-DIO-ChR2:YFP revealed that 100% and 88% expressed mRNAs for Kiss1 and vesicular glutamate transporter 2, respectively. Whole-cell, voltage-clamp recordings from nonfluorescent postsynaptic ARC neurons showed that low frequency photo-stimulation (0.5 Hz) of Kiss1-ChR2:YFP neurons elicited a fast glutamatergic inward current in POMC and AgRP neurons. Paired-pulse, photo-stimulation revealed paired-pulse depression, which is indicative of greater glutamate release, in the castrated male mice compared with gonad-intact male mice. Group I and group II metabotropic glutamate receptor agonists depolarized and hyperpolarized POMC and AgRP neurons, respectively, which was mimicked by high frequency photo-stimulation (20 Hz) of Kiss1ARC neurons. Therefore, POMC and AgRP neurons receive direct steroid- and frequency-dependent glutamatergic synaptic input from Kiss1ARC neurons in male mice, which may be a critical pathway for Kiss1 neurons to help coordinate energy homeostasis and reproduction. PMID:27093227

  13. Antibodies and a cysteine-modifying reagent show correspondence of M current in neurons to KCNQ2 and KCNQ3 K+ channels

    PubMed Central

    Roche, John P; Westenbroek, Ruth; Sorom, Abraham J; Hille, Bertil; Mackie, Ken; Shapiro, Mark S

    2002-01-01

    KCNQ K+ channels are thought to underlie the M current of neurons. To probe if the KCNQ2 and KCNQ3 subtypes underlie the M current of rat superior cervical ganglia (SCG) neurons and of hippocampus, we raised specific antibodies against them and also used the cysteine-alkylating agent N-ethylmaleimide (NEM) as an additional probe of subunit composition. Tested on tsA-201 (tsA) cells transfected with cloned KCNQ1-5 subunits, our antibodies showed high affinity and selectivity for the appropriate subtype. The antibodies immunostained SCG neurons and hippocampal sections at levels similar to those for channels expressed in tsA cells, indicating that KCNQ2 and KCNQ3 are present in SCG and hippocampal neurons. Some hippocampal regions contained only KCNQ2 or KCNQ3 subunits, suggesting the presence of M currents produced by channels other than KCNQ2/3 heteromultimers. We found that NEM augmented M currents in SCG neurons and KCNQ2/3 currents in tsA cells via strong voltage-independent and modest voltage-dependent actions. Expression of individual KCNQ subunits in tsA cells revealed voltage-independent augmentation of KCNQ2, but not KCNQ1 nor KCNQ3, currents by NEM indicating that this action on SCG M currents likely localizes to KCNQ2. Much of the voltage-independent action is lost after the C242T mutation in KCNQ2. The correspondence of NEM effects on expressed KCNQ2/3 and SCG M currents, along with the antibody labelling, provide further evidence that KCNQ2 and KCNQ3 subunits strongly contribute to the M current of neurons. The site of NEM action may be important for treatment of diseases caused by under-expression of these channels. PMID:12466226

  14. A long noncoding RNA contributes to neuropathic pain by silencing Kcna2 in primary afferent neurons

    PubMed Central

    Zhao, Xiuli; Tang, Zongxiang; Zhang, Hongkang; Atianjoh, Fidelis E.; Zhao, Jian-Yuan; Liang, Lingli; Wang, Wei; Guan, Xiaowei; Kao, Sheng-Chin; Tiwari, Vinod; Gao, Yong-Jing; Hoffman, Paul N.; Cui, Hengmi; Li, Min; Dong, Xinzhong; Tao, Yuan-Xiang

    2013-01-01

    Neuropathic pain is a refractory disease characterized by maladaptive changes in gene transcription and translation within the sensory pathway. Long noncoding RNAs (lncRNAs) are emerging as new players in gene regulation, but how lncRNAs operate in the development of neuropathic pain is unclear. Here we identify a conserved lncRNA for Kcna2 (named Kcna2 antisense RNA) in first-order sensory neurons of rat dorsal root ganglion (DRG). Peripheral nerve injury increases Kcna2 antisense RNA expression in injured DRG through activation of myeloid zinc finger protein 1, a transcription factor that binds to Kcna2 antisense RNA gene promoter. Mimicking this increase downregulates Kcna2, reduces total Kv current, increases excitability in DRG neurons, and produces neuropathic pain symptoms. Blocking this increase reverses nerve injury-induced downregulation of DRG Kcna2 and attenuates development and maintenance of neuropathic pain. These findings suggest native Kcna2 antisense RNA as a new therapeutic target for the treatment of neuropathic pain. PMID:23792947

  15. Different Mechanisms Regulate Productive Herpes Simplex Virus 1 (HSV-1) and HSV-2 Infections in Adult Trigeminal Neurons

    PubMed Central

    Ma, AyeAye; Margolis, Mathew S.

    2013-01-01

    Herpes simplex virus 1 (HSV-1) and HSV-2 establish latency in different neuronal subtypes (A5+ and KH10+) in murine trigeminal ganglia, results which correlate with restricted productive infection in these neurons in vitro. HSV-2 latency-associated transcript (LAT) contains a cis-acting regulatory element near the transcription start site that promotes productive infection in A5+ neurons and a second element in exon 1 that inhibits productive infection in KH10+ neurons. HSV-1 contains no such regulatory sequences, demonstrating different mechanisms for regulating productive HSV infection in neurons. PMID:23514893

  16. Single-Neuron NMDA Receptor Phenotype Influences Neuronal Rewiring and Reintegration following Traumatic Injury

    PubMed Central

    Patel, Tapan P.; Ventre, Scott C.; Geddes-Klein, Donna; Singh, Pallab K.

    2014-01-01

    Alterations in the activity of neural circuits are a common consequence of traumatic brain injury (TBI), but the relationship between single-neuron properties and the aggregate network behavior is not well understood. We recently reported that the GluN2B-containing NMDA receptors (NMDARs) are key in mediating mechanical forces during TBI, and that TBI produces a complex change in the functional connectivity of neuronal networks. Here, we evaluated whether cell-to-cell heterogeneity in the connectivity and aggregate contribution of GluN2B receptors to [Ca2+]i before injury influenced the functional rewiring, spontaneous activity, and network plasticity following injury using primary rat cortical dissociated neurons. We found that the functional connectivity of a neuron to its neighbors, combined with the relative influx of calcium through distinct NMDAR subtypes, together contributed to the individual neuronal response to trauma. Specifically, individual neurons whose [Ca2+]i oscillations were largely due to GluN2B NMDAR activation lost many of their functional targets 1 h following injury. In comparison, neurons with large GluN2A contribution or neurons with high functional connectivity both independently protected against injury-induced loss in connectivity. Mechanistically, we found that traumatic injury resulted in increased uncorrelated network activity, an effect linked to reduction of the voltage-sensitive Mg2+ block of GluN2B-containing NMDARs. This uncorrelated activation of GluN2B subtypes after injury significantly limited the potential for network remodeling in response to a plasticity stimulus. Together, our data suggest that two single-cell characteristics, the aggregate contribution of NMDAR subtypes and the number of functional connections, influence network structure following traumatic injury. PMID:24647941

  17. Thiamine Deficiency Increases Ca2+ Current and CaV1.2 L-type Ca2+ Channel Levels in Cerebellum Granular Neurons.

    PubMed

    Moreira-Lobo, Daniel C; Cruz, Jader S; Silva, Flavia R; Ribeiro, Fabíola M; Kushmerick, Christopher; Oliveira, Fernando A

    2017-04-01

    Thiamine (vitamin B1) is co-factor for three pivotal enzymes for glycolytic metabolism: pyruvate dehydrogenase, α-ketoglutarate dehydrogenase, and transketolase. Thiamine deficiency leads to neurodegeneration of several brain regions, especially the cerebellum. In addition, several neurodegenerative diseases are associated with impairments of glycolytic metabolism, including Alzheimer's disease. Therefore, understanding the link between dysfunction of the glycolytic pathway and neuronal death will be an important step to comprehend the mechanism and progression of neuronal degeneration as well as the development of new treatment for neurodegenerative states. Here, using an in vitro model to study the effects of thiamine deficiency on cerebellum granule neurons, we show an increase in Ca 2+ current density and Ca V 1.2 expression. These results indicate a link between alterations in glycolytic metabolism and changes to Ca 2+ dynamics, two factors that have been implicated in neurodegeneration.

  18. Neuromodulation targets intrinsic cardiac neurons to attenuate neuronally mediated atrial arrhythmias.

    PubMed

    Gibbons, David D; Southerland, E Marie; Hoover, Donald B; Beaumont, Eric; Armour, J Andrew; Ardell, Jeffrey L

    2012-02-01

    Our objective was to determine whether atrial fibrillation (AF) results from excessive activation of intrinsic cardiac neurons (ICNs) and, if so, whether select subpopulations of neurons therein represent therapeutic targets for suppression of this arrhythmogenic potential. Trains of five electrical stimuli (0.3-1.2 mA, 1 ms) were delivered during the atrial refractory period to mediastinal nerves (MSN) on the superior vena cava to evoke AF. Neuroanatomical studies were performed by injecting the neuronal tracer DiI into MSN sites that induced AF. Functional studies involved recording of neuronal activity in situ from the right atrial ganglionated plexus (RAGP) in response to MSN stimulation (MSNS) prior to and following neuromodulation involving either preemptive spinal cord stimulation (SCS; T(1)-T(3), 50 Hz, 200-ms duration) or ganglionic blockade (hexamethonium, 5 mg/kg). The tetramethylindocarbocyanine perchlorate (DiI) neuronal tracer labeled a subset (13.2%) of RAGP neurons, which also colocalized with cholinergic or adrenergic markers. A subset of DiI-labeled RAGP neurons were noncholinergic/nonadrenergic. MSNS evoked an ∼4-fold increase in RAGP neuronal activity from baseline, which SCS reduced by 43%. Hexamethonium blocked MSNS-evoked increases in neuronal activity. MSNS evoked AF in 78% of right-sided MSN sites, which SCS reduced to 33% and hexamethonium reduced to 7%. MSNS-induced bradycardia was maintained with SCS but was mitigated by hexamethonium. We conclude that MSNS activates subpopulations of intrinsic cardiac neurons, thereby resulting in the formation of atrial arrhythmias leading to atrial fibrillation. Stabilization of ICN local circuit neurons by SCS or the local circuit and autonomic efferent neurons with hexamethonium reduces the arrhythmogenic potential.

  19. PRRT2 controls neuronal excitability by negatively modulating Na+ channel 1.2/1.6 activity.

    PubMed

    Fruscione, Floriana; Valente, Pierluigi; Sterlini, Bruno; Romei, Alessandra; Baldassari, Simona; Fadda, Manuela; Prestigio, Cosimo; Giansante, Giorgia; Sartorelli, Jacopo; Rossi, Pia; Rubio, Alicia; Gambardella, Antonio; Nieus, Thierry; Broccoli, Vania; Fassio, Anna; Baldelli, Pietro; Corradi, Anna; Zara, Federico; Benfenati, Fabio

    2018-04-01

    See Lerche (doi:10.1093/brain/awy073) for a scientific commentary on this article.Proline-rich transmembrane protein 2 (PRRT2) is the causative gene for a heterogeneous group of familial paroxysmal neurological disorders that include seizures with onset in the first year of life (benign familial infantile seizures), paroxysmal kinesigenic dyskinesia or a combination of both. Most of the PRRT2 mutations are loss-of-function leading to haploinsufficiency and 80% of the patients carry the same frameshift mutation (c.649dupC; p.Arg217Profs*8), which leads to a premature stop codon. To model the disease and dissect the physiological role of PRRT2, we studied the phenotype of neurons differentiated from induced pluripotent stem cells from previously described heterozygous and homozygous siblings carrying the c.649dupC mutation. Single-cell patch-clamp experiments on induced pluripotent stem cell-derived neurons from homozygous patients showed increased Na+ currents that were fully rescued by expression of wild-type PRRT2. Closely similar electrophysiological features were observed in primary neurons obtained from the recently characterized PRRT2 knockout mouse. This phenotype was associated with an increased length of the axon initial segment and with markedly augmented spontaneous and evoked firing and bursting activities evaluated, at the network level, by multi-electrode array electrophysiology. Using HEK-293 cells stably expressing Nav channel subtypes, we demonstrated that the expression of PRRT2 decreases the membrane exposure and Na+ current of Nav1.2/Nav1.6, but not Nav1.1, channels. Moreover, PRRT2 directly interacted with Nav1.2/Nav1.6 channels and induced a negative shift in the voltage-dependence of inactivation and a slow-down in the recovery from inactivation. In addition, by co-immunoprecipitation assays, we showed that the PRRT2-Nav interaction also occurs in brain tissue. The study demonstrates that the lack of PRRT2 leads to a hyperactivity of voltage

  20. PRRT2 controls neuronal excitability by negatively modulating Na+ channel 1.2/1.6 activity

    PubMed Central

    Fruscione, Floriana; Valente, Pierluigi; Sterlini, Bruno; Romei, Alessandra; Baldassari, Simona; Fadda, Manuela; Prestigio, Cosimo; Giansante, Giorgia; Sartorelli, Jacopo; Rossi, Pia; Rubio, Alicia; Gambardella, Antonio; Nieus, Thierry; Broccoli, Vania; Fassio, Anna; Baldelli, Pietro; Corradi, Anna; Zara, Federico

    2018-01-01

    Abstract See Lerche (doi:10.1093/brain/awy073) for a scientific commentary on this article. Proline-rich transmembrane protein 2 (PRRT2) is the causative gene for a heterogeneous group of familial paroxysmal neurological disorders that include seizures with onset in the first year of life (benign familial infantile seizures), paroxysmal kinesigenic dyskinesia or a combination of both. Most of the PRRT2 mutations are loss-of-function leading to haploinsufficiency and 80% of the patients carry the same frameshift mutation (c.649dupC; p.Arg217Profs*8), which leads to a premature stop codon. To model the disease and dissect the physiological role of PRRT2, we studied the phenotype of neurons differentiated from induced pluripotent stem cells from previously described heterozygous and homozygous siblings carrying the c.649dupC mutation. Single-cell patch-clamp experiments on induced pluripotent stem cell-derived neurons from homozygous patients showed increased Na+ currents that were fully rescued by expression of wild-type PRRT2. Closely similar electrophysiological features were observed in primary neurons obtained from the recently characterized PRRT2 knockout mouse. This phenotype was associated with an increased length of the axon initial segment and with markedly augmented spontaneous and evoked firing and bursting activities evaluated, at the network level, by multi-electrode array electrophysiology. Using HEK-293 cells stably expressing Nav channel subtypes, we demonstrated that the expression of PRRT2 decreases the membrane exposure and Na+ current of Nav1.2/Nav1.6, but not Nav1.1, channels. Moreover, PRRT2 directly interacted with Nav1.2/Nav1.6 channels and induced a negative shift in the voltage-dependence of inactivation and a slow-down in the recovery from inactivation. In addition, by co-immunoprecipitation assays, we showed that the PRRT2-Nav interaction also occurs in brain tissue. The study demonstrates that the lack of PRRT2 leads to a hyperactivity of

  1. Metformin Protects Neurons against Oxygen-Glucose Deprivation/Reoxygenation -Induced Injury by Down-Regulating MAD2B.

    PubMed

    Meng, Xianfang; Chu, Guangpin; Yang, Zhihua; Qiu, Ping; Hu, Yue; Chen, Xiaohe; Peng, Wenpeng; Ye, Chen; He, Fang-Fang; Zhang, Chun

    2016-01-01

    Metformin, the common medication for type II diabetes, has protective effects on cerebral ischemia. However, the molecular mechanisms are far from clear. Mitotic arrest deficient 2-like protein 2 (MAD2B), an inhibitor of the anaphase-promoting complex (APC), is widely expressed in hippocampal and cortical neurons and plays an important role in mediating high glucose-induced neurotoxicity. The present study investigated whether metformin modifies the expression of MAD2B and to exert its neuroprotective effects in primary cultured cortical neurons during oxygen-glucose deprivation/reoxygenation (OGD/R), a widely used in vitro model of ischemia/reperfusion. Primary cortical neurons were cultured, deprived of oxygen-glucose for 1 h, and then recovered with oxygen-glucose for 12 h and 24 h. Cell viability was measured by detecting the levels of lactate dehydrogenase (LDH) in culture medium. The levels of MAD2B, cyclin B and p-histone 3 were measured by Western blot. Cell viability of neurons was reduced under oxygen-glucose deprivation/reoxygenation (OGD/R). The expression of MAD2B was increased under OGD/R. The levels of cyclin B1, which is a substrate of APC, were also increased. Moreover, OGD/R up-regulated the phosphorylation levels of histone 3, which is the induction of aberrant re-entry of post-mitotic neurons. However, pretreatment of neurons with metformin alleviated OGD/R-induced injury. Metformin further decreased the expression of MAD2B, cyclin B1 and phosphorylation levels of histone 3. Metformin exerts its neuroprotective effect through regulating the expression of MAD2B in neurons under OGD/R. © 2016 The Author(s) Published by S. Karger AG, Basel.

  2. Involvement of serotonin 2A receptor activation in modulating medial prefrontal cortex and amygdala neuronal activation during novelty-exposure.

    PubMed

    Hervig, Mona El-Sayed; Jensen, Nadja Cecilie Hvid; Rasmussen, Nadja Bredo; Rydbirk, Rasmus; Olesen, Mikkel Vestergaard; Hay-Schmidt, Anders; Pakkenberg, Bente; Aznar, Susana

    2017-05-30

    The medial prefrontal cortex (PFC) plays a major role in executive function by exerting a top-down control onto subcortical areas. Novelty-induced frontal cortex activation is 5-HT 2A receptor (5-HT 2A R) dependent. Here, we further investigated how blockade of 5-HT 2A Rs in mice exposed to a novel open-field arena affects medial PFC activation and basolateral amygdala (BLA) reactivity. We used c-Fos immunoreactivity (IR) as a marker of neuronal activation and stereological quantification for obtaining the total number of c-Fos-IR neurons as a measure of regional activation. We further examined the impact of 5-HT 2A R blockade on the striatal-projecting BLA neurons. Systemic administration of ketanserin (0.5mg/kg) prior to novel open-field exposure resulted in reduced total numbers of c-Fos-IR cells in dorsomedial PFC areas and the BLA. Moreover, there was a positive correlation between the relative time spent in the centre of the open-field and BLA c-Fos-IR in the ketanserin-treated animals. Unilateral medial PFC lesions blocked this effect, ascertaining an involvement of this frontal cortex area. On the other hand, medial PFC lesioning exacerbated the more anxiogenic-like behaviour of the ketanserin-treated animals, upholding its involvement in modulating averseness. Ketanserin did not affect the number of activated striatal-projecting BLA neurons (measured by number of Cholera Toxin b (CTb) retrograde labelled neurons also being c-Fos-IR) following CTb injection in the ventral striatum. These results support a role of 5-HT 2A R activation in modulating mPFC and BLA activation during exposure to a novel environment, which may be interrelated. Conversely, 5-HT 2A R blockade does not seem to affect the amygdala-striatal projection. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Signaling via the transcriptionally regulated activin receptor 2B is a novel mediator of neuronal cell death during chicken ciliary ganglion development.

    PubMed

    Koszinowski, S; Buss, K; Kaehlcke, K; Krieglstein, K

    2015-04-01

    The TGF-β ligand superfamily members activin A and BMP control important aspects of embryonic neuronal development and differentiation. Both are known to bind to activin receptor subtypes IIA (ActRIIA) and IIB, while in the avian ciliary ganglion (CG), so far only ActRIIA-expression has been described. We show that the expression of ACVR2B, coding for the ActRIIB, is tightly regulated during CG development and the knockdown of ACVR2B expression leads to a deregulation in the execution of neuronal apoptosis and therefore affects ontogenetic programmed cell death in vivo. While the differentiation of choroid neurons was impeded in the knockdown, pointing toward a reduction in activin A-mediated neural differentiation signaling, naturally occurring neuronal cell death in the CG was not prevented by follistatin treatment. Systemic injections of the BMP antagonist noggin, on the other hand, reduced the number of apoptotic neurons to a similar extent as ACVR2B knockdown. We therefore propose a novel pathway in the regulation of CG neuron ontogenetic programmed cell death, which could be mediated by BMP and signals via the ActRIIB. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  4. Scratch2 prevents cell cycle re-entry by repressing miR-25 in postmitotic primary neurons.

    PubMed

    Rodríguez-Aznar, Eva; Barrallo-Gimeno, Alejandro; Nieto, M Angela

    2013-03-20

    During the development of the nervous system the regulation of cell cycle, differentiation, and survival is tightly interlinked. Newly generated neurons must keep cell cycle components under strict control, as cell cycle re-entry leads to neuronal degeneration and death. However, despite their relevance, the mechanisms controlling this process remain largely unexplored. Here we show that Scratch2 is involved in the control of the cell cycle in neurons in the developing spinal cord of the zebrafish embryo. scratch2 knockdown induces postmitotic neurons to re-enter mitosis. Scratch2 prevents cell cycle re-entry by maintaining high levels of the cycle inhibitor p57 through the downregulation of miR-25. Thus, Scratch2 appears to safeguard the homeostasis of postmitotic primary neurons by preventing cell cycle re-entry.

  5. Macroglia-derived thrombospondin 2 regulates alterations of presynaptic proteins of retinal neurons following elevated hydrostatic pressure.

    PubMed

    Wang, Shuchao; Hu, Tu; Wang, Zhen; Li, Na; Zhou, Lihong; Liao, Lvshuang; Wang, Mi; Liao, Libin; Wang, Hui; Zeng, Leping; Fan, Chunling; Zhou, Hongkang; Xiong, Kun; Huang, Jufang; Chen, Dan

    2017-01-01

    Many studies on retinal injury and repair following elevated intraocular pressure suggest that the survival ratio of retinal neurons has been improved by various measures. However, the visual function recovery is far lower than expected. The homeostasis of retinal synapses in the visual signal pathway is the key structural basis for the delivery of visual signals. Our previous studies found that complicated changes in the synaptic structure between retinal neurons occurred much earlier than obvious degeneration of retinal ganglion cells in rat retinae. The lack of consideration of these earlier retinal synaptic changes in the rescue strategy may be partly responsible for the limited visual function recovery with the types of protective methods for retinal neurons used following elevated intraocular pressure. Thus, research on the modulatory mechanisms of the synaptic changes after elevated intraocular pressure injury may give new light to visual function rescue. In this study, we found that thrombospondin 2, an important regulator of synaptogenesis in central nervous system development, was distributed in retinal macroglia cells, and its receptor α2δ-1 was in retinal neurons. Cell cultures including mixed retinal macroglia cells/neuron cultures and retinal neuron cultures were exposed to elevated hydrostatic pressure for 2 h. The expression levels of glial fibrillary acidic protein (the marker of activated macroglia cells), thrombospondin 2, α2δ-1 and presynaptic proteins were increased following elevated hydrostatic pressure in mixed cultures, but the expression levels of postsynaptic proteins were not changed. SiRNA targeting thrombospondin 2 could decrease the upregulation of presynaptic proteins induced by the elevated hydrostatic pressure. However, in retinal neuron cultures, elevated hydrostatic pressure did not affect the expression of presynaptic or postsynaptic proteins. Rather, the retinal neuron cultures with added recombinant thrombospondin 2

  6. CGP37157, an inhibitor of the mitochondrial Na+/Ca2+ exchanger, protects neurons from excitotoxicity by blocking voltage-gated Ca2+ channels.

    PubMed

    Ruiz, A; Alberdi, E; Matute, C

    2014-04-10

    Inhibition of the mitochondrial Na(+)/Ca(2+) exchanger (NCLX) by CGP37157 is protective in models of neuronal injury that involve disruption of intracellular Ca(2+) homeostasis. However, the Ca(2+) signaling pathways and stores underlying neuroprotection by that inhibitor are not well defined. In the present study, we analyzed how intracellular Ca(2+) levels are modulated by CGP37157 (10 μM) during NMDA insults in primary cultures of rat cortical neurons. We initially assessed the presence of NCLX in mitochondria of cultured neurons by immunolabeling, and subsequently, we analyzed the effects of CGP37157 on neuronal Ca(2+) homeostasis using cameleon-based mitochondrial Ca(2+) and cytosolic Ca(2+) ([Ca(2+)]i) live imaging. We observed that NCLX-driven mitochondrial Ca(2+) exchange occurs in cortical neurons under basal conditions as CGP37157 induced a decrease in [Ca(2)]i concomitant with a Ca(2+) accumulation inside the mitochondria. In turn, CGP37157 also inhibited mitochondrial Ca(2+) efflux after the stimulation of acetylcholine receptors. In contrast, CGP37157 strongly prevented depolarization-induced [Ca(2+)]i increase by blocking voltage-gated Ca(2+) channels (VGCCs), whereas it did not induce depletion of ER Ca(2+) stores. Moreover, mitochondrial Ca(2+) overload was reduced as a consequence of diminished Ca(2+) entry through VGCCs. The decrease in cytosolic and mitochondrial Ca(2+) overload by CGP37157 resulted in a reduction of excitotoxic mitochondrial damage, characterized here by a reduction in mitochondrial membrane depolarization, oxidative stress and calpain activation. In summary, our results provide evidence that during excitotoxicity CGP37157 modulates cytosolic and mitochondrial Ca(2+) dynamics that leads to attenuation of NMDA-induced mitochondrial dysfunction and neuronal cell death by blocking VGCCs.

  7. CGP37157, an inhibitor of the mitochondrial Na+/Ca2+ exchanger, protects neurons from excitotoxicity by blocking voltage-gated Ca2+ channels

    PubMed Central

    Ruiz, A; Alberdi, E; Matute, C

    2014-01-01

    Inhibition of the mitochondrial Na+/Ca2+ exchanger (NCLX) by CGP37157 is protective in models of neuronal injury that involve disruption of intracellular Ca2+ homeostasis. However, the Ca2+ signaling pathways and stores underlying neuroprotection by that inhibitor are not well defined. In the present study, we analyzed how intracellular Ca2+ levels are modulated by CGP37157 (10 μM) during NMDA insults in primary cultures of rat cortical neurons. We initially assessed the presence of NCLX in mitochondria of cultured neurons by immunolabeling, and subsequently, we analyzed the effects of CGP37157 on neuronal Ca2+ homeostasis using cameleon-based mitochondrial Ca2+ and cytosolic Ca2+ ([Ca2+]i) live imaging. We observed that NCLX-driven mitochondrial Ca2+ exchange occurs in cortical neurons under basal conditions as CGP37157 induced a decrease in [Ca2]i concomitant with a Ca2+ accumulation inside the mitochondria. In turn, CGP37157 also inhibited mitochondrial Ca2+ efflux after the stimulation of acetylcholine receptors. In contrast, CGP37157 strongly prevented depolarization-induced [Ca2+]i increase by blocking voltage-gated Ca2+ channels (VGCCs), whereas it did not induce depletion of ER Ca2+ stores. Moreover, mitochondrial Ca2+ overload was reduced as a consequence of diminished Ca2+ entry through VGCCs. The decrease in cytosolic and mitochondrial Ca2+ overload by CGP37157 resulted in a reduction of excitotoxic mitochondrial damage, characterized here by a reduction in mitochondrial membrane depolarization, oxidative stress and calpain activation. In summary, our results provide evidence that during excitotoxicity CGP37157 modulates cytosolic and mitochondrial Ca2+ dynamics that leads to attenuation of NMDA-induced mitochondrial dysfunction and neuronal cell death by blocking VGCCs. PMID:24722281

  8. Protective actions of the vesicular monoamine transporter 2 (VMAT2) in monoaminergic neurons.

    PubMed

    Guillot, Thomas S; Miller, Gary W

    2009-04-01

    Vesicular monoamine transporters (VMATs) are responsible for the packaging of neurotransmitters such as dopamine, serotonin, norepinephrine, and epinephrine into synaptic vesicles. These proteins evolved from precursors in the major facilitator superfamily of transporters and are among the members of the toxin extruding antiporter family. While the primary function of VMATs is to sequester neurotransmitters within vesicles, they can also translocate toxicants away from cytosolic sites of action. In the case of dopamine, this dual role of VMAT2 is combined-dopamine is more readily oxidized in the cytosol where it can cause oxidative stress so packaging into vesicles serves two purposes: neurotransmission and neuroprotection. Furthermore, the deleterious effects of exogenous toxicants on dopamine neurons, such as MPTP, can be attenuated by VMAT2 activity. The active metabolite of MPTP can be kept within vesicles and prevented from disrupting mitochondrial function thereby sparing the dopamine neuron. The highly addictive drug methamphetamine is also neurotoxic to dopamine neurons by using dopamine itself to destroy the axon terminals. Methamphetamine interferes with vesicular sequestration and increases the production of dopamine, escalating the amount in the cytosol and leading to oxidative damage of terminal components. Vesicular transport seems to resist this process by sequestering much of the excess dopamine, which is illustrated by the enhanced methamphetamine neurotoxicity in VMAT2-deficient mice. It is increasingly evident that VMAT2 provides neuroprotection from both endogenous and exogenous toxicants and that while VMAT2 has been adapted by eukaryotes for synaptic transmission, it is derived from phylogenetically ancient proteins that originally evolved for the purpose of cellular protection.

  9. Neurons from the adult human dentate nucleus: neural networks in the neuron classification.

    PubMed

    Grbatinić, Ivan; Marić, Dušica L; Milošević, Nebojša T

    2015-04-07

    Topological (central vs. border neuron type) and morphological classification of adult human dentate nucleus neurons according to their quantified histomorphological properties using neural networks on real and virtual neuron samples. In the real sample 53.1% and 14.1% of central and border neurons, respectively, are classified correctly with total of 32.8% of misclassified neurons. The most important result present 62.2% of misclassified neurons in border neurons group which is even greater than number of correctly classified neurons (37.8%) in that group, showing obvious failure of network to classify neurons correctly based on computational parameters used in our study. On the virtual sample 97.3% of misclassified neurons in border neurons group which is much greater than number of correctly classified neurons (2.7%) in that group, again confirms obvious failure of network to classify neurons correctly. Statistical analysis shows that there is no statistically significant difference in between central and border neurons for each measured parameter (p>0.05). Total of 96.74% neurons are morphologically classified correctly by neural networks and each one belongs to one of the four histomorphological types: (a) neurons with small soma and short dendrites, (b) neurons with small soma and long dendrites, (c) neuron with large soma and short dendrites, (d) neurons with large soma and long dendrites. Statistical analysis supports these results (p<0.05). Human dentate nucleus neurons can be classified in four neuron types according to their quantitative histomorphological properties. These neuron types consist of two neuron sets, small and large ones with respect to their perykarions with subtypes differing in dendrite length i.e. neurons with short vs. long dendrites. Besides confirmation of neuron classification on small and large ones, already shown in literature, we found two new subtypes i.e. neurons with small soma and long dendrites and with large soma and short

  10. Dopamine neurons in culture express VGLUT2 explaining their capacity to release glutamate at synapses in addition to dopamine.

    PubMed

    Dal Bo, Gregory; St-Gelais, Fannie; Danik, Marc; Williams, Sylvain; Cotton, Mathieu; Trudeau, Louis-Eric

    2004-03-01

    Dopamine neurons have been suggested to use glutamate as a cotransmitter. To identify the basis of such a phenotype, we have examined the expression of the three recently identified vesicular glutamate transporters (VGLUT1-3) in postnatal rat dopamine neurons in culture. We found that the majority of isolated dopamine neurons express VGLUT2, but not VGLUT1 or 3. In comparison, serotonin neurons express only VGLUT3. Single-cell RT-PCR experiments confirmed the presence of VGLUT2 mRNA in dopamine neurons. Arguing for phenotypic heterogeneity among axon terminals, we find that only a proportion of terminals established by dopamine neurons are VGLUT2-positive. Taken together, our results provide a basis for the ability of dopamine neurons to release glutamate as a cotransmitter. A detailed analysis of the conditions under which DA neurons gain or loose a glutamatergic phenotype may provide novel insight into pathophysiological processes that underlie diseases such as schizophrenia, Parkinson's disease and drug dependence.

  11. Interfering of the Reelin/ApoER2/PSD95 Signaling Axis Reactivates Dendritogenesis of Mature Hippocampal Neurons.

    PubMed

    Ampuero, Estibaliz; Jury, Nur; Härtel, Steffen; Marzolo, María-Paz; van Zundert, Brigitte

    2017-05-01

    Reelin, an extracellular glycoprotein secreted in embryonic and adult brain, participates in neuronal migration and neuronal plasticity. Extensive evidence shows that reelin via activation of the ApoER2 and VLDLR receptors promotes dendrite and spine formation during early development. Further evidence suggests that reelin signaling is needed to maintain a stable architecture in mature neurons, but, direct evidence is lacking. During activity-dependent maturation of the neuronal circuitry, the synaptic protein PSD95 is inserted into the postsynaptic membrane to induce structural refinement and stability of spines and dendrites. Given that ApoER2 interacts with PSD95, we tested if reelin signaling interference in adult neurons reactivates the dendritic architecture. Unlike findings in developing cultures, the presently obtained in vitro and in vivo data show, for the first time, that reelin signaling interference robustly increase dendritogenesis and reduce spine density in mature hippocampal neurons. In particular, the expression of a mutant ApoER2 form (ApoER2-tailless), which is unable to interact with PSD95 and hence cannot transduce reelin signaling, resulted in robust dendritogenesis in mature hippocampal neurons in vitro. These results indicate that reelin/ApoER2/PSD95 signaling is important for neuronal structure maintenance in mature neurons. Mechanistically, obtained immunofluorescent data indicate that reelin signaling impairment reduced synaptic PSD95 levels, consequently leading to synaptic re-insertion of NR2B-NMDARs. Our findings underscore the importance of reelin in maintaining adult network stability and reveal a new mode for reactivating dendritogenesis in neurological disorders where dendritic arbor complexity is limited, such as in depression, Alzheimer's disease, and stroke. J. Cell. Physiol. 232: 1187-1199, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  12. Exposure to advertisement calls of reproductive competitors activates vocal-acoustic and catecholaminergic neurons in the plainfin midshipman fish, Porichthys notatus.

    PubMed

    Petersen, Christopher L; Timothy, Miky; Kim, D Spencer; Bhandiwad, Ashwin A; Mohr, Robert A; Sisneros, Joseph A; Forlano, Paul M

    2013-01-01

    While the neural circuitry and physiology of the auditory system is well studied among vertebrates, far less is known about how the auditory system interacts with other neural substrates to mediate behavioral responses to social acoustic signals. One species that has been the subject of intensive neuroethological investigation with regard to the production and perception of social acoustic signals is the plainfin midshipman fish, Porichthys notatus, in part because acoustic communication is essential to their reproductive behavior. Nesting male midshipman vocally court females by producing a long duration advertisement call. Females localize males by their advertisement call, spawn and deposit all their eggs in their mate's nest. As multiple courting males establish nests in close proximity to one another, the perception of another male's call may modulate individual calling behavior in competition for females. We tested the hypothesis that nesting males exposed to advertisement calls of other males would show elevated neural activity in auditory and vocal-acoustic brain centers as well as differential activation of catecholaminergic neurons compared to males exposed only to ambient noise. Experimental brains were then double labeled by immunofluorescence (-ir) for tyrosine hydroxylase (TH), an enzyme necessary for catecholamine synthesis, and cFos, an immediate-early gene product used as a marker for neural activation. Males exposed to other advertisement calls showed a significantly greater percentage of TH-ir cells colocalized with cFos-ir in the noradrenergic locus coeruleus and the dopaminergic periventricular posterior tuberculum, as well as increased numbers of cFos-ir neurons in several levels of the auditory and vocal-acoustic pathway. Increased activation of catecholaminergic neurons may serve to coordinate appropriate behavioral responses to male competitors. Additionally, these results implicate a role for specific catecholaminergic neuronal groups in

  13. Exposure to Advertisement Calls of Reproductive Competitors Activates Vocal-Acoustic and Catecholaminergic Neurons in the Plainfin Midshipman Fish, Porichthys notatus

    PubMed Central

    Petersen, Christopher L.; Timothy, Miky; Kim, D. Spencer; Bhandiwad, Ashwin A.; Mohr, Robert A.; Sisneros, Joseph A.; Forlano, Paul M.

    2013-01-01

    While the neural circuitry and physiology of the auditory system is well studied among vertebrates, far less is known about how the auditory system interacts with other neural substrates to mediate behavioral responses to social acoustic signals. One species that has been the subject of intensive neuroethological investigation with regard to the production and perception of social acoustic signals is the plainfin midshipman fish, Porichthys notatus, in part because acoustic communication is essential to their reproductive behavior. Nesting male midshipman vocally court females by producing a long duration advertisement call. Females localize males by their advertisement call, spawn and deposit all their eggs in their mate’s nest. As multiple courting males establish nests in close proximity to one another, the perception of another male’s call may modulate individual calling behavior in competition for females. We tested the hypothesis that nesting males exposed to advertisement calls of other males would show elevated neural activity in auditory and vocal-acoustic brain centers as well as differential activation of catecholaminergic neurons compared to males exposed only to ambient noise. Experimental brains were then double labeled by immunofluorescence (-ir) for tyrosine hydroxylase (TH), an enzyme necessary for catecholamine synthesis, and cFos, an immediate-early gene product used as a marker for neural activation. Males exposed to other advertisement calls showed a significantly greater percentage of TH-ir cells colocalized with cFos-ir in the noradrenergic locus coeruleus and the dopaminergic periventricular posterior tuberculum, as well as increased numbers of cFos-ir neurons in several levels of the auditory and vocal-acoustic pathway. Increased activation of catecholaminergic neurons may serve to coordinate appropriate behavioral responses to male competitors. Additionally, these results implicate a role for specific catecholaminergic neuronal groups

  14. A simple method for characterizing passive and active neuronal properties: application to striatal neurons.

    PubMed

    Lepora, Nathan F; Blomeley, Craig P; Hoyland, Darren; Bracci, Enrico; Overton, Paul G; Gurney, Kevin

    2011-11-01

    The study of active and passive neuronal dynamics usually relies on a sophisticated array of electrophysiological, staining and pharmacological techniques. We describe here a simple complementary method that recovers many findings of these more complex methods but relies only on a basic patch-clamp recording approach. Somatic short and long current pulses were applied in vitro to striatal medium spiny (MS) and fast spiking (FS) neurons from juvenile rats. The passive dynamics were quantified by fitting two-compartment models to the short current pulse data. Lumped conductances for the active dynamics were then found by compensating this fitted passive dynamics within the current-voltage relationship from the long current pulse data. These estimated passive and active properties were consistent with previous more complex estimations of the neuron properties, supporting the approach. Relationships within the MS and FS neuron types were also evident, including a graduation of MS neuron properties consistent with recent findings about D1 and D2 dopamine receptor expression. Application of the method to simulated neuron data supported the hypothesis that it gives reasonable estimates of membrane properties and gross morphology. Therefore detailed information about the biophysics can be gained from this simple approach, which is useful for both classification of neuron type and biophysical modelling. Furthermore, because these methods rely upon no manipulations to the cell other than patch clamping, they are ideally suited to in vivo electrophysiology. © 2011 The Authors. European Journal of Neuroscience © 2011 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

  15. CHD5, a brain-specific paralog of Mi2 chromatin remodeling enzymes, regulates expression of neuronal genes.

    PubMed

    Potts, Rebecca Casaday; Zhang, Peisu; Wurster, Andrea L; Precht, Patricia; Mughal, Mohamed R; Wood, William H; Zhang, Yonqing; Becker, Kevin G; Mattson, Mark P; Pazin, Michael J

    2011-01-01

    CHD5 is frequently deleted in neuroblastoma and is a tumor suppressor gene. However, little is known about the role of CHD5 other than it is homologous to chromatin remodeling ATPases. We found CHD5 mRNA was restricted to the brain; by contrast, most remodeling ATPases were broadly expressed. CHD5 protein isolated from mouse brain was associated with HDAC2, p66ß, MTA3 and RbAp46 in a megadalton complex. CHD5 protein was detected in several rat brain regions and appeared to be enriched in neurons. CHD5 protein was predominantly nuclear in primary rat neurons and brain sections. Microarray analysis revealed genes that were upregulated and downregulated when CHD5 was depleted from primary neurons. CHD5 depletion altered expression of neuronal genes, transcription factors, and brain-specific subunits of the SWI/SNF remodeling enzyme. Expression of gene sets linked to aging and Alzheimer's disease were strongly altered by CHD5 depletion from primary neurons. Chromatin immunoprecipitation revealed CHD5 bound to these genes, suggesting the regulation was direct. Together, these results indicate that CHD5 protein is found in a NuRD-like multi-protein complex. CHD5 expression is restricted to the brain, unlike the closely related family members CHD3 and CHD4. CHD5 regulates expression of neuronal genes, cell cycle genes and remodeling genes. CHD5 is linked to regulation of genes implicated in aging and Alzheimer's disease.

  16. CHD5, a Brain-Specific Paralog of Mi2 Chromatin Remodeling Enzymes, Regulates Expression of Neuronal Genes

    PubMed Central

    Potts, Rebecca Casaday; Zhang, Peisu; Wurster, Andrea L.; Precht, Patricia; Mughal, Mohamed R.; Wood, William H.; Zhang, Yonqing; Becker, Kevin G.; Mattson, Mark P.; Pazin, Michael J.

    2011-01-01

    CHD5 is frequently deleted in neuroblastoma and is a tumor suppressor gene. However, little is known about the role of CHD5 other than it is homologous to chromatin remodeling ATPases. We found CHD5 mRNA was restricted to the brain; by contrast, most remodeling ATPases were broadly expressed. CHD5 protein isolated from mouse brain was associated with HDAC2, p66ß, MTA3 and RbAp46 in a megadalton complex. CHD5 protein was detected in several rat brain regions and appeared to be enriched in neurons. CHD5 protein was predominantly nuclear in primary rat neurons and brain sections. Microarray analysis revealed genes that were upregulated and downregulated when CHD5 was depleted from primary neurons. CHD5 depletion altered expression of neuronal genes, transcription factors, and brain-specific subunits of the SWI/SNF remodeling enzyme. Expression of gene sets linked to aging and Alzheimer's disease were strongly altered by CHD5 depletion from primary neurons. Chromatin immunoprecipitation revealed CHD5 bound to these genes, suggesting the regulation was direct. Together, these results indicate that CHD5 protein is found in a NuRD-like multi-protein complex. CHD5 expression is restricted to the brain, unlike the closely related family members CHD3 and CHD4. CHD5 regulates expression of neuronal genes, cell cycle genes and remodeling genes. CHD5 is linked to regulation of genes implicated in aging and Alzheimer's disease. PMID:21931736

  17. Noradrenergic modulation of masseter muscle activity during natural rapid eye movement sleep requires glutamatergic signalling at the trigeminal motor nucleus

    PubMed Central

    Schwarz, Peter B; Mir, Saba; Peever, John H

    2014-01-01

    Noradrenergic neurotransmission in the brainstem is closely coupled to changes in muscle activity across the sleep–wake cycle, and noradrenaline is considered to be a key excitatory neuromodulator that reinforces the arousal-related stimulus on motoneurons to drive movement. However, it is unknown if α-1 noradrenoceptor activation increases motoneuron responsiveness to excitatory glutamate (AMPA) receptor-mediated inputs during natural behaviour. We studied the effects of noradrenaline on AMPA receptor-mediated motor activity at the motoneuron level in freely behaving rats, particularly during rapid eye movement (REM) sleep, a period during which both AMPA receptor-triggered muscle twitches and periods of muscle quiescence in which AMPA drive is silent are exhibited. Male rats were subjected to electromyography and electroencephalography recording to monitor sleep and waking behaviour. The implantation of a cannula into the trigeminal motor nucleus of the brainstem allowed us to perfuse noradrenergic and glutamatergic drugs by reverse microdialysis, and thus to use masseter muscle activity as an index of motoneuronal output. We found that endogenous excitation of both α-1 noradrenoceptor and AMPA receptors during waking are coupled to motor activity; however, REM sleep exhibits an absence of endogenous α-1 noradrenoceptor activity. Importantly, exogenous α-1 noradrenoceptor stimulation cannot reverse the muscle twitch suppression induced by AMPA receptor blockade and nor can it elevate muscle activity during quiet REM, a phase when endogenous AMPA receptor activity is subthreshold. We conclude that the presence of an endogenous glutamatergic drive is necessary for noradrenaline to trigger muscle activity at the level of the motoneuron in an animal behaving naturally. PMID:24860176

  18. Optogenetic identification of hypothalamic orexin neuron projections to paraventricular spinally projecting neurons.

    PubMed

    Dergacheva, Olga; Yamanaka, Akihiro; Schwartz, Alan R; Polotsky, Vsevolod Y; Mendelowitz, David

    2017-04-01

    Orexin neurons, and activation of orexin receptors, are generally thought to be sympathoexcitatory; however, the functional connectivity between orexin neurons and a likely sympathetic target, the hypothalamic spinally projecting neurons (SPNs) in the paraventricular nucleus of the hypothalamus (PVN) has not been established. To test the hypothesis that orexin neurons project directly to SPNs in the PVN, channelrhodopsin-2 (ChR2) was selectively expressed in orexin neurons to enable photoactivation of ChR2-expressing fibers while examining evoked postsynaptic currents in SPNs in rat hypothalamic slices. Selective photoactivation of orexin fibers elicited short-latency postsynaptic currents in all SPNs tested ( n = 34). These light-triggered responses were heterogeneous, with a majority being excitatory glutamatergic responses (59%) and a minority of inhibitory GABAergic (35%) and mixed glutamatergic and GABAergic currents (6%). Both glutamatergic and GABAergic responses were present in the presence of tetrodotoxin and 4-aminopyridine, suggesting a monosynaptic connection between orexin neurons and SPNs. In addition to generating postsynaptic responses, photostimulation facilitated action potential firing in SPNs (current clamp configuration). Glutamatergic, but not GABAergic, postsynaptic currents were diminished by application of the orexin receptor antagonist almorexant, indicating orexin release facilitates glutamatergic neurotransmission in this pathway. This work identifies a neuronal circuit by which orexin neurons likely exert sympathoexcitatory control of cardiovascular function. NEW & NOTEWORTHY This is the first study to establish, using innovative optogenetic approaches in a transgenic rat model, that there are robust heterogeneous projections from orexin neurons to paraventricular spinally projecting neurons, including excitatory glutamatergic and inhibitory GABAergic neurotransmission. Endogenous orexin release modulates glutamatergic, but not

  19. Metabolic reprogramming during neuronal differentiation from aerobic glycolysis to neuronal oxidative phosphorylation

    PubMed Central

    Zheng, Xinde; Boyer, Leah; Jin, Mingji; Mertens, Jerome; Kim, Yongsung; Ma, Li; Ma, Li; Hamm, Michael; Gage, Fred H; Hunter, Tony

    2016-01-01

    How metabolism is reprogrammed during neuronal differentiation is unknown. We found that the loss of hexokinase (HK2) and lactate dehydrogenase (LDHA) expression, together with a switch in pyruvate kinase gene splicing from PKM2 to PKM1, marks the transition from aerobic glycolysis in neural progenitor cells (NPC) to neuronal oxidative phosphorylation. The protein levels of c-MYC and N-MYC, transcriptional activators of the HK2 and LDHA genes, decrease dramatically. Constitutive expression of HK2 and LDHA during differentiation leads to neuronal cell death, indicating that the shut-off aerobic glycolysis is essential for neuronal survival. The metabolic regulators PGC-1α and ERRγ increase significantly upon neuronal differentiation to sustain the transcription of metabolic and mitochondrial genes, whose levels are unchanged compared to NPCs, revealing distinct transcriptional regulation of metabolic genes in the proliferation and post-mitotic differentiation states. Mitochondrial mass increases proportionally with neuronal mass growth, indicating an unknown mechanism linking mitochondrial biogenesis to cell size. DOI: http://dx.doi.org/10.7554/eLife.13374.001 PMID:27282387

  20. NG2 glial cells regulate neuroimmunological responses to maintain neuronal function and survival.

    PubMed

    Nakano, Masayuki; Tamura, Yasuhisa; Yamato, Masanori; Kume, Satoshi; Eguchi, Asami; Takata, Kumi; Watanabe, Yasuyoshi; Kataoka, Yosky

    2017-02-14

    NG2-expressing neural progenitor cells (i.e., NG2 glial cells) maintain their proliferative and migratory activities even in the adult mammalian central nervous system (CNS) and produce myelinating oligodendrocytes and astrocytes. Although NG2 glial cells have been observed in close proximity to neuronal cell bodies in order to receive synaptic inputs, substantive non-proliferative roles of NG2 glial cells in the adult CNS remain unclear. In the present study, we generated NG2-HSVtk transgenic rats and selectively ablated NG2 glial cells in the adult CNS. Ablation of NG2 glial cells produced defects in hippocampal neurons due to excessive neuroinflammation via activation of the interleukin-1 beta (IL-1β) pro-inflammatory pathway, resulting in hippocampal atrophy. Furthermore, we revealed that the loss of NG2 glial cell-derived hepatocyte growth factor (HGF) exacerbated these abnormalities. Our findings suggest that NG2 glial cells maintain neuronal function and survival via the control of neuroimmunological function.

  1. Neuronal overexpression of Ube3a isoform 2 causes behavioral impairments and neuroanatomical pathology relevant to 15q11.2-q13.3 duplication syndrome.

    PubMed

    Copping, Nycole A; Christian, Sarah G B; Ritter, Dylan J; Islam, M Saharul; Buscher, Nathalie; Zolkowska, Dorota; Pride, Michael C; Berg, Elizabeth L; LaSalle, Janine M; Ellegood, Jacob; Lerch, Jason P; Reiter, Lawrence T; Silverman, Jill L; Dindot, Scott V

    2017-10-15

    Maternally derived copy number gains of human chromosome 15q11.2-q13.3 (Dup15q syndrome or Dup15q) cause intellectual disability, epilepsy, developmental delay, hypotonia, speech impairments, and minor dysmorphic features. Dup15q syndrome is one of the most common and penetrant chromosomal abnormalities observed in individuals with autism spectrum disorder (ASD). Although ∼40 genes are located in the 15q11.2-q13.3 region, overexpression of the ubiquitin-protein E3A ligase (UBE3A) gene is thought to be the predominant molecular cause of the phenotypes observed in Dup15q syndrome. The UBE3A gene demonstrates maternal-specific expression in neurons and loss of maternal UBE3A causes Angelman syndrome, a neurodevelopmental disorder with some overlapping neurological features to Dup15q. To directly test the hypothesis that overexpression of UBE3A is an important underlying molecular cause of neurodevelopmental dysfunction, we developed and characterized a mouse overexpressing Ube3a isoform 2 in excitatory neurons. Ube3a isoform 2 is conserved between mouse and human and known to play key roles in neuronal function. Transgenic mice overexpressing Ube3a isoform 2 in excitatory forebrain neurons exhibited increased anxiety-like behaviors, learning impairments, and reduced seizure thresholds. However, these transgenic mice displayed normal social approach, social interactions, and repetitive motor stereotypies that are relevant to ASD. Reduced forebrain, hippocampus, striatum, amygdala, and cortical volume were also observed. Altogether, these findings show neuronal overexpression of Ube3a isoform 2 causes phenotypes translatable to neurodevelopmental disorders. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  2. Nucleus Accumbens Dopamine D2-Receptor Expressing Neurons Control Behavioral Flexibility in a Place Discrimination Task in the IntelliCage

    ERIC Educational Resources Information Center

    Macpherson, Tom; Morita, Makiko; Wang, Yanyan; Sasaoka, Toshikuni; Sawa, Akira; Hikida, Takatoshi

    2016-01-01

    Considerable evidence has demonstrated a critical role for the nucleus accumbens (NAc) in the acquisition and flexibility of behavioral strategies. These processes are guided by the activity of two discrete neuron types, dopamine D1- or D2-receptor expressing medium spiny neurons (D1-/D2-MSNs). Here we used the IntelliCage, an automated…

  3. The Sirtuin 2 microtubule deacetylase is an abundant neuronal protein that accumulates in the aging CNS

    PubMed Central

    Maxwell, Michele M.; Tomkinson, Elizabeth M.; Nobles, Johnathan; Wizeman, John W.; Amore, Allison M.; Quinti, Luisa; Chopra, Vanita; Hersch, Steven M.; Kazantsev, Aleksey G.

    2011-01-01

    Sirtuin 2 (SIRT2) is one of seven known mammalian protein deacetylases homologous to the yeast master lifespan regulator Sir2. In recent years, the sirtuin protein deacetylases have emerged as candidate therapeutic targets for many human diseases, including metabolic and age-dependent neurological disorders. In non-neuronal cells, SIRT2 has been shown to function as a tubulin deacetylase and a key regulator of cell division and differentiation. However, the distribution and function of the SIRT2 microtubule (MT) deacetylase in differentiated, postmitotic neurons remain largely unknown. Here, we show abundant and preferential expression of specific isoforms of SIRT2 in the mammalian central nervous system and find that a previously uncharacterized form, SIRT2.3, exhibits age-dependent accumulation in the mouse brain and spinal cord. Further, our studies reveal that focal areas of endogenous SIRT2 expression correlate with reduced α-tubulin acetylation in primary mouse cortical neurons and suggest that the brain-enriched species of SIRT2 may function as the predominant MT deacetylases in mature neurons. Recent reports have demonstrated an association between impaired tubulin acetyltransferase activity and neurodegenerative disease; viewed in this light, our results showing age-dependent accumulation of the SIRT2 neuronal MT deacetylase in wild-type mice suggest a functional link between tubulin acetylation patterns and the aging brain. PMID:21791548

  4. Detection of phasic dopamine by D1 and D2 striatal medium spiny neurons.

    PubMed

    Yapo, Cedric; Nair, Anu G; Clement, Lorna; Castro, Liliana R; Hellgren Kotaleski, Jeanette; Vincent, Pierre

    2017-12-15

    Brief dopamine events are critical actors of reward-mediated learning in the striatum; the intracellular cAMP-protein kinase A (PKA) response of striatal medium spiny neurons to such events was studied dynamically using a combination of biosensor imaging in mouse brain slices and in silico simulations. Both D1 and D2 medium spiny neurons can sense brief dopamine transients in the sub-micromolar range. While dopamine transients profoundly change cAMP levels in both types of medium spiny neurons, the PKA-dependent phosphorylation level remains unaffected in D2 neurons. At the level of PKA-dependent phosphorylation, D2 unresponsiveness depends on protein phosphatase-1 (PP1) inhibition by DARPP-32. Simulations suggest that D2 medium spiny neurons could detect transient dips in dopamine level. The phasic release of dopamine in the striatum determines various aspects of reward and action selection, but the dynamics of the dopamine effect on intracellular signalling remains poorly understood. We used genetically encoded FRET biosensors in striatal brain slices to quantify the effect of transient dopamine on cAMP or PKA-dependent phosphorylation levels, and computational modelling to further explore the dynamics of this signalling pathway. Medium-sized spiny neurons (MSNs), which express either D 1 or D 2 dopamine receptors, responded to dopamine by an increase or a decrease in cAMP, respectively. Transient dopamine showed similar sub-micromolar efficacies on cAMP in both D1 and D2 MSNs, thus challenging the commonly accepted notion that dopamine efficacy is much higher on D 2 than on D 1 receptors. However, in D2 MSNs, the large decrease in cAMP level triggered by transient dopamine did not translate to a decrease in PKA-dependent phosphorylation level, owing to the efficient inhibition of protein phosphatase 1 by DARPP-32. Simulations further suggested that D2 MSNs can also operate in a 'tone-sensing' mode, allowing them to detect transient dips in basal dopamine

  5. Prevention of Ca(2+)-mediated action potentials in GABAergic local circuit neurones of rat thalamus by a transient K+ current.

    PubMed Central

    Pape, H C; Budde, T; Mager, R; Kisvárday, Z F

    1994-01-01

    1. Neurones enzymatically dissociated from the rat dorsal lateral geniculate nucleus (LGN) were identified as GABAergic local circuit interneurones and geniculocortical relay cells, based upon quantitative analysis of soma profiles, immunohistochemical detection of GABA or glutamic acid decarboxylase, and basic electrogenic behaviour. 2. During whole-cell current-clamp recording, isolated LGN neurones generated firing patterns resembling those in intact tissue, with the most striking difference relating to the presence in relay cells of a Ca2+ action potential with a low threshold of activation, capable of triggering fast spikes, and the absence of a regenerative Ca2+ response with a low threshold of activation in local circuit cells. 3. Whole-cell voltage-clamp experiments demonstrated that both classes of LGN neurones possess at least two voltage-dependent membrane currents which operate in a range of membrane potentials negative to the threshold for generation of Na(+)-K(+)-mediated spikes: the T-type Ca2+ current (IT) and an A-type K+ current (IA). Taking into account the differences in membrane surface area, the average size of IT was similar in the two types of neurones, and interneurones possessed a slightly larger A-conductance. 4. In local circuit neurones, the ranges of steady-state inactivation and activation of IT and IA were largely overlapping (VH = 81.1 vs. -82.8 mV), both currents activated at around -70 mV, and they rapidly increased in amplitude with further depolarization. In relay cells, the inactivation curve of IT was negatively shifted along the voltage axis by about 20 mV compared with that of IA (Vh = -86.1 vs. -69.2 mV), and the activation threshold for IT (at -80 mV) was 20 mV more negative than that for IA. In interneurones, the activation range of IT was shifted to values more positive than that in relay cells (Vh = -54.9 vs. -64.5 mV), whereas the activation range of IA was more negative (Vh = -25.2 vs. -14.5 mV). 5. Under whole

  6. Rescue of hyperexcitability in hippocampal CA1 neurons from Mecp2 (-/y) mouse through surface potential neutralization

    PubMed Central

    Mironov, Sergej L.

    2018-01-01

    Hyperventilation is a known feature of Rett syndrome (RTT). However, how hyperventilation is related to other RTT symptoms such as hyperexcitability is unknown. Intense breathing during hyperventilation induces hypocapnia and culminates in respiratory alkalosis. Alkalinization of extracellular milieu can trigger epilepsy in patients who already have neuronal hyperexcitability. By combining patch-clamp electrophysiology and quantitative glutamate imaging, we compared excitability of CA1 neurons of WT and Mecp2 (-/y) mice, and analyzed the biophysical properties of subthreshold membrane channels. The results show that Mecp2 (-/y) CA1 neurons are hyperexcitable in normal pH (7.4) and are increasingly vulnerable to alkaline extracellular pH (8.4), during which their excitability increased further. Under normal pH conditions, an abnormal negative shift in the voltage-dependencies of HCN (hyperpolarization-activated cyclic nucleotide-gated) and calcium channels in the CA1 neurons of Mecp2 (-/y) mice was observed. Alkaline pH also enhanced excitability in wild-type (WT) CA1 neurons through modulation of the voltage dependencies of HCN- and calcium channels. Additionally alkaline pH augmented spontaneous glutamate release and burst firing in WT CA1 neurons. Conversely, acidic pH (6.4) and 8 mM Mg2+ exerted the opposite effect, and diminished hyperexcitability in Mecp2 (-/y) CA1 neurons. We propose that the observed effects of pH and Mg2+ are mediated by changes in the neuronal membrane surface potential, which consecutively modulates the gating of HCN and calcium channels. The results provide insight to pivotal cellular mechanisms that can regulate neuronal excitability and help to devise treatment strategies for hyperexcitability induced symptoms of Rett syndrome. PMID:29621262

  7. A quantitative analysis of the local connectivity between pyramidal neurons in layers 2/3 of the rat visual cortex.

    PubMed

    Hellwig, B

    2000-02-01

    This study provides a detailed quantitative estimate for local synaptic connectivity between neocortical pyramidal neurons. A new way of obtaining such an estimate is presented. In acute slices of the rat visual cortex, four layer 2 and four layer 3 pyramidal neurons were intracellularly injected with biocytin. Axonal and dendritic arborizations were three-dimensionally reconstructed with the aid of a computer-based camera lucida system. In a computer experiment, pairs of pre- and postsynaptic neurons were formed and potential synaptic contacts were calculated. For each pair, the calculations were carried out for a whole range of distances (0 to 500 microm) between the presynaptic and the postsynaptic neuron, in order to estimate cortical connectivity as a function of the spatial separation of neurons. It was also differentiated whether neurons were situated in the same or in different cortical layers. The data thus obtained was used to compute connection probabilities, the average number of contacts between neurons, the frequency of specific numbers of contacts and the total number of contacts a dendritic tree receives from the surrounding cortical volume. Connection probabilities ranged from 50% to 80% for directly adjacent neurons and from 0% to 15% for neurons 500 microm apart. In many cases, connections were mediated by one contact only. However, close neighbors made on average up to 3 contacts with each other. The question as to whether the method employed in this study yields a realistic estimate of synaptic connectivity is discussed. It is argued that the results can be used as a detailed blueprint for building artificial neural networks with a cortex-like architecture.

  8. Spatial dynamics of action potentials estimated by dendritic Ca(2+) signals in insect projection neurons.

    PubMed

    Ogawa, Hiroto; Mitani, Ruriko

    2015-11-13

    The spatial dynamics of action potentials, including their propagation and the location of spike initiation zone (SIZ), are crucial for the computation of a single neuron. Compared with mammalian central neurons, the spike dynamics of invertebrate neurons remain relatively unknown. Thus, we examined the spike dynamics based on single spike-induced Ca(2+) signals in the dendrites of cricket mechanosensory projection neurons, known as giant interneurons (GIs). The Ca(2+) transients induced by a synaptically evoked single spike were larger than those induced by an antidromic spike, whereas subthreshold synaptic potentials caused no elevation of Ca(2+). These results indicate that synaptic activity enhances the dendritic Ca(2+) influx through voltage-gated Ca(2+) channels. Stimulation of the presynaptic sensory afferents ipsilateral to the recording site evoked a dendritic spike with higher amplitude than contralateral stimulation, thereby suggesting that alteration of the spike waveform resulted in synaptic enhancement of the dendritic Ca(2+) transients. The SIZ estimated from the spatial distribution of the difference in the Ca(2+) amplitude was distributed throughout the right and left dendritic branches across the primary neurite connecting them in GIs. Copyright © 2015 Elsevier Inc. All rights reserved.

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

    PubMed

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

    2014-03-13

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

  10. L-type voltage-dependent calcium channel is involved in the snake venom group IA secretory phospholipase A2-induced neuronal apoptosis.

    PubMed

    Yagami, Tatsurou; Yamamoto, Yasuhiro; Kohma, Hiromi; Nakamura, Tsutomu; Takasu, Nobuo; Okamura, Noboru

    2013-03-01

    Snake venom group IA secretory phospholipase A2 (sPLA2-IA) is known as a neurotoxin. Snake venom sPLA2s are neurotoxic in vivo and in vitro, causing synergistic neurotoxicity to cortical cultures when applied with toxic concentrations of glutamate. However, it has not yet been cleared sufficiently how sPLA2-IA exerts neurotoxicity. Here, we found sPLA2-IA induced neuronal cell death in a concentration-dependent manner. This death was a delayed response requiring a latent time for 6h. sPLA2-IA-induced neuronal cell death was accompanied with apoptotic blebbing, condensed chromatin, and fragmented DNA, exhibiting apoptotic features. NMDA receptor blockers suppressed the neurotoxicity of sPLA2-IA, but an AMPA receptor blocker did not. Interestingly, L-type voltage-dependent Ca(2+) channel (L-VDCC) blocker significantly protected neurons from the sPLA2-IA-induced apoptosis. On the other hand, neither N-VDCC blockers nor P/Q-VDCC blocker did. In conclusion, we demonstrated that sPLA2-IA induced neuronal cell death via apoptosis. Furthermore, the present study suggests that not only NMDA receptor but also L-VDCC contributed to the neurotoxicity of snake venom sPLA2-IA. Copyright © 2013 Elsevier Inc. All rights reserved.

  11. Protective effect of Nrf2-ARE activator isolated from green perilla leaves on dopaminergic neuronal loss in a Parkinson's disease model.

    PubMed

    Masaki, Yuta; Izumi, Yasuhiko; Matsumura, Atsuko; Akaike, Akinori; Kume, Toshiaki

    2017-03-05

    Parkinson's disease (PD) is a neurodegenerative disorder characterized by a selective loss of dopaminergic neurons in the substantia nigra (SN), and oxidative stress is thought to contribute to the pathogenesis. The nuclear factor erythroid 2-related factor 2 (Nrf2)-antioxidant response element (ARE) pathway, which is a cellular defense system against oxidative stress, is a promising target for therapeutics aimed at reducing neuronal death in PD. Previously, we have isolated 2',3'-dihydroxy-4',6'-dimethoxychalcone (DDC) from green perilla leaves as an activator of the Nrf2-ARE pathway. The present study showed the protective effect of DDC on PD models in vivo and in vitro. In a 6-hydroxydopamine (6-OHDA)-induced hemiparkinson's disease mouse model, intracerebral administration of DDC suppressed the dopaminergic neuronal loss and behavioral dysfunction. DDC upregulated the expression of heme oxygenase-1 (HO-1), one of the ARE-driven antioxidant enzymes, in astrocytes and microglia of the SN. In primary mesencephalic cultures, treatment with DDC also increased the HO-1 expression in astrocytes and microglia. DDC showed a protective effect against 6-OHDA-induced dopaminergic neuronal death, and the effect was suppressed by an HO-1 inhibitor. These results suggest that DDC prevents dopaminergic neurons from oxidative stress by upregulation of glial expression of HO-1. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. β1-adrenergic receptors activate two distinct signaling pathways in striatal neurons

    PubMed Central

    Meitzen, John; Luoma, Jessie I.; Stern, Christopher M.; Mermelstein, Paul G.

    2010-01-01

    Monoamine action in the dorsal striatum and nucleus accumbens plays essential roles in striatal physiology. Although research often focuses on dopamine and its receptors, norepinephrine and adrenergic receptors are also crucial in regulating striatal function. While noradrenergic neurotransmission has been identified in the striatum, little is known regarding the signaling pathways activated by β-adrenergic receptors in this brain region. Using cultured striatal neurons, we characterized a novel signaling pathway by which activation of β1-adrenergic receptors leads to the rapid phosphorylation of cAMP Response Element Binding Protein (CREB), a transcription-factor implicated as a molecular switch underlying long-term changes in brain function. Norepinephrine-mediated CREB phosphorylation requires β1-adrenergic receptor stimulation of a receptor tyrosine kinase, ultimately leading to the activation of a Ras/Raf/MEK/MAPK/MSK signaling pathway. Activation of β1-adrenergic receptors also induces CRE-dependent transcription and increased c-fos expression. In addition, stimulation of β1-adrenergic receptors produces cAMP production, but surprisingly, β1-adrenergic receptor activation of adenylyl cyclase was not functionally linked to rapid CREB phosphorylation. These findings demonstrate that activation of β1-adrenergic receptors on striatal neurons can stimulate two distinct signaling pathways. These adrenergic actions can produce long-term changes in gene expression, as well as rapidly modulate cellular physiology. By elucidating the mechanisms by which norepinephrine and β1-adrenergic receptor activation affects striatal physiology, we provide the means to more fully understand the role of monoamines in modulating striatal function, specifically how norepinephrine and β1-adrenergic receptors may affect striatal physiology. PMID:21143600

  13. Tryptophan hydroxylase 2 (TPH2) in a neuronal cell line: modulation by cell differentiation and NRSF/rest activity.

    PubMed

    Gentile, Maria Teresa; Nawa, Yukino; Lunardi, Gianluigi; Florio, Tullio; Matsui, Hiroaki; Colucci-D'Amato, Luca

    2012-12-01

    Serotonin (5-HT) is a neurotransmitter involved in many aspects of the neuronal function. The synthesis of 5-HT is initiated by the hydroxylation of tryptophan, catalyzed by tryptophan hydroxylase (TPH). Two isoforms of TPH (TPH1 and TPH2) have been identified, with TPH2 almost exclusively expressed in the brain. Following TPH2 discovery, it was reported that polymorphisms of both gene and non-coding regions are associated with a spectrum of psychiatric disorders. Thus, insights into the mechanisms that specifically regulate TPH2 expression and its modulation by exogenous stimuli may represent a new therapeutic approach to modify serotonergic neurotransmission. To this aim, a CNS-originated cell line expressing TPH2 endogenously represents a valid model system. In this study, we report that TPH2 transcript and protein are modulated by neuronal differentiation in the cell line A1 mes-c-myc (A1). Moreover, we show luciferase activity driven by the human TPH2 promoter region and demonstrate that upon mutation of the NRSF/REST responsive element, the promoter activity strongly increases with cell differentiation. Our data suggest that A1 cells could represent a model system, allowing an insight into the mechanisms of regulation of TPH2 and to identify novel therapeutic targets in the development of drugs for the management of psychiatric disorders. © 2012 The Authors Journal of Neurochemistry © 2012 International Society for Neurochemistry.

  14. Acute and chronic effects of noradrenergic enhancement on transcranial direct current stimulation-induced neuroplasticity in humans.

    PubMed

    Kuo, Hsiao-I; Paulus, Walter; Batsikadze, Giorgi; Jamil, Asif; Kuo, Min-Fang; Nitsche, Michael A

    2017-02-15

    Chronic administration of the selective noradrenaline reuptake inhibitor (NRI) reboxetine (RBX) increased and prolonged the long-term potentiation-like plasticity induced by anodal transcranial direct current stimulation (tDCS) for over 24 h. Chronic administration of RBX converted cathodal tDCS-induced long-term depression-like plasticity into facilitation for 120 min. Chronic noradrenergic activity enhancement on plasticity of the human brain might partially explain the delayed therapeutic impact of selective NRIs in depression and other neuropsychiatric diseases. Noradrenaline affects cognition and motor learning processes via its impact on long-term potentiation (LTP) and depression (LTD). We aimed to explore the impact of single dose and chronic administration of the selective noradrenaline reuptake inhibitor (NRI) reboxetine (RBX) on plasticity induced by transcranial direct current stimulation (tDCS) in healthy humans via a double-blinded, placebo-controlled, randomized crossover study. Sixteen healthy volunteers received placebo or single dose RBX (8 mg) before anodal or cathodal tDCS of the primary motor cortex. Afterwards, the same subjects took RBX (8 mg day -1 ) consecutively for 21 days. During this period, two additional interventions were performed (RBX with anodal or cathodal tDCS), to explore the impact of chronic RBX treatment on plasticity. Plasticity was monitored by motor-evoked potential amplitudes elicited by transcranial magnetic stimulation. Chronic administration of RBX increased and prolonged the LTP-like plasticity induced by anodal tDCS for over 24 h. Chronic RBX significantly converted cathodal tDCS-induced LTD-like plasticity into facilitation, as compared to the single dose condition, for 120 min after stimulation. The results show a prominent impact of chronic noradrenergic enhancement on plasticity of the human brain that might partially explain the delayed therapeutic impact of selective NRIs in depression and other

  15. A single-neuron tracing study of arkypallidal and prototypic neurons in healthy rats.

    PubMed

    Fujiyama, Fumino; Nakano, Takashi; Matsuda, Wakoto; Furuta, Takahiro; Udagawa, Jun; Kaneko, Takeshi

    2016-12-01

    The external globus pallidus (GP) is known as a relay nucleus of the indirect pathway of the basal ganglia. Recent studies in dopamine-depleted and healthy rats indicate that the GP comprises two main types of pallidofugal neurons: the so-called "prototypic" and "arkypallidal" neurons. However, the reconstruction of complete arkypallidal neurons in healthy rats has not been reported. Here we visualized the entire axonal arborization of four single arkypallidal neurons and six single prototypic neurons in rat brain using labeling with a viral vector expressing membrane-targeted green fluorescent protein and examined the distribution of axon boutons in the target nuclei. Results revealed that not only the arkypallidal neurons but nearly all of the prototypic neurons projected to the striatum with numerous axon varicosities. Thus, the striatum is a major target nucleus for pallidal neurons. Arkypallidal and prototypic GP neurons located in the calbindin-positive and calbindin-negative regions mainly projected to the corresponding positive and negative regions in the striatum. Because the GP and striatum calbindin staining patterns reflect the topographic organization of the striatopallidal projection, the striatal neurons in the sensorimotor and associative regions constitute the reciprocal connection with the GP neurons in the corresponding regions.

  16. Gold nanoparticle-assisted all optical localized stimulation and monitoring of Ca2+ signaling in neurons

    PubMed Central

    Lavoie-Cardinal, Flavie; Salesse, Charleen; Bergeron, Éric; Meunier, Michel; De Koninck, Paul

    2016-01-01

    Light-assisted manipulation of cells to control membrane activity or intracellular signaling has become a major avenue in life sciences. However, the ability to perform subcellular light stimulation to investigate localized signaling has been limited. Here, we introduce an all optical method for the stimulation and the monitoring of localized Ca2+ signaling in neurons that takes advantage of plasmonic excitation of gold nanoparticles (AuNPs). We show with confocal microscopy that 800 nm laser pulse application onto a neuron decorated with a few AuNPs triggers a transient increase in free Ca2+, measured optically with GCaMP6s. We show that action potentials, measured electrophysiologically, can be induced with this approach. We demonstrate activation of local Ca2+ transients and Ca2+ signaling via CaMKII in dendritic domains, by illuminating a single or few functionalized AuNPs specifically targeting genetically-modified neurons. This NP-Assisted Localized Optical Stimulation (NALOS) provides a new complement to light-dependent methods for controlling neuronal activity and cell signaling. PMID:26857748

  17. Closing the Phenotypic Gap between Transformed Neuronal Cell Lines in Culture and Untransformed Neurons

    NASA Technical Reports Server (NTRS)

    Myers, Tereance A.; Nickerson, Cheryl A.; Kaushal, Deepak; Ott, C. Mark; HonerzuBentrup, Kerstin; Ramamurthy, Rajee; Nelman-Gonzales, Mayra; Pierson, Duane L.; Philipp, Mario T.

    2008-01-01

    Studies of neuronal dysfunction in the central nervous system (CNS) are frequently limited by the failure of primary neurons to propagate in vitro. Neuronal cell lines can be substituted for primary cells but they often misrepresent normal conditions. We hypothesized that a dimensional (3-D) cell culture system would drive the phenotype of transformed neurons closer to that of untransformed cells. In our studies comparing 3-D versus 2-dimensional (2-D) culture, neuronal SH-SY5Y (SY) cells underwent distinct morphological changes combined with a significant drop in their rate of cell division. Expression of the proto-oncogene N-myc and the RNA binding protein HuD was decreased in 3-D culture as compared to standard 2-D conditions. We observed a decline in the anti-apoptotic protein Bcl-2 in 3-D culture, coupled with increased expression of the pro-apoptotic proteins Bax and Bak. Moreover, thapsigargin (TG)-induced apoptosis was enhanced in the 3-D cells. Microarray analysis demonstrated significantly differing mRNA levels for over 700 genes in the cells of each culture type. These results indicate that a 3-D culture approach narrows the phenotypic gap between neuronal cell lines and primary neurons. The resulting cells may readily be used for in vitro research of neuronal pathogenesis.

  18. Neuronal overexpression of cyclooxygenase-2 does not alter the neuroinflammatory response during brain innate immune activation.

    PubMed

    Aid, Saba; Parikh, Nishant; Palumbo, Sara; Bosetti, Francesca

    2010-07-12

    Neuroinflammation is a critical component in the progression of several neurological and neurodegenerative diseases and cyclooxygenases (COX)-1 and -2 are key regulators of innate immune responses. We recently demonstrated that COX-1 deletion attenuates, whereas COX-2 deletion enhances, the neuroinflammatory response, blood-brain barrier permeability and leukocyte recruitment during lipopolysaccharide (LPS)-induced innate immune activation. Here, we used transgenic mice, which overexpressed human COX-2 via neuron-specific Thy-1 promoter (TgCOX-2), causing elevated prostaglandins (PGs) levels. We tested whether neuronal COX-2 overexpression affects the glial response to a single intracerebroventricular injection of LPS, which produces a robust neuroinflammatory reaction. Relative to non-transgenic controls (NTg), 7 month-old TgCOX-2 did not show any basal neuroinflammation, as assessed by gene expression of markers of inflammation and oxidative stress, neuronal damage, as assessed by Fluoro-JadeB staining, or systemic inflammation, as assessed by plasma levels of IL-1beta and corticosterone. Twenty-four hours after LPS injection, all mice showed increased microglial activation, as indicated by Iba1 immunostaining, neuronal damage, mRNA expression of cytokines (TNF-alpha, IL-6), reactive oxygen expressing enzymes (iNOS and NADPH oxidase subunits), endogenous COX-2, cPLA(2) and mPGES-1, and hippocampal and cortical IL-1beta levels. However, the increases were similar in TgCOX-2 and NTg. In NTg, LPS increased brain PGE(2) to the levels observed in TgCOX-2. These results suggest that PGs derived from neuronal COX-2 do not play a role in the neuroinflammatory response to acute activation of brain innate immunity. This is likely due to the direct effect of LPS on glial rather than neuronal cells. Published by Elsevier Ireland Ltd.

  19. Cardiovascular dysautonomia in Parkinson Disease: From pathophysiology to pathogenesis

    PubMed Central

    Goldstein, David S.

    2011-01-01

    Signs or symptoms of impaired autonomic regulation of the circulation often attend Parkinson disease (PD). This review covers biomarkers and mechanisms of autonomic cardiovascular abnormalities in PD and related alpha-synucleinopathies. The clearest clinical laboratory correlate of dysautonomia in PD is loss of myocardial noradrenergic innervation, detected by cardiac sympathetic neuroimaging. About 30–40% of PD patients have orthostatic hypotension (OH), defined as a persistent, consistent fall in systolic blood pressure of at least 20 mm Hg or diastolic blood pressure of at least 10 mm Hg within three minutes of change in position from supine to standing. Neuroimaging evidence of cardiac sympathetic denervation is universal in PD with OH (PD+OH). In PD without OH about half the patients have diffuse left ventricular myocardial sympathetic denervation, a substantial minority have partial denervation confined to the inferolateral or apical walls, and a small number have normal innervation. Among patients with partial denervation the neuronal loss invariably progresses over time, and in those with normal innervation at least some loss eventually becomes evident. Thus, cardiac sympathetic denervation in PD occurs independently of the movement disorder. PD+OH also entails extra-cardiac noradrenergic denervation, but this is not as severe as in pure autonomic failure. PD+OH patients have failure of both the parasympathetic and sympathetic components of the arterial baroreflex. OH in PD therefore seems to reflect a “triple whammy” of cardiac and extra-cardiac noradrenergic denervation and baroreflex failure. In contrast, most patients with multiple system atrophy, which can resemble PD+OH clinically, do not have evidence for cardiac or extra-cardiac noradrenergic denervation. Catecholamines in the neuronal cytoplasm are potentially toxic, via spontaneous and enzyme-catalyzed oxidation. Normally cytoplasmic catecholamines are efficiently taken up into vesicles via

  20. Accumulation of GABAergic neurons, causing a focal ambient GABA gradient, and downregulation of KCC2 are induced during microgyrus formation in a mouse model of polymicrogyria.

    PubMed

    Wang, Tianying; Kumada, Tatsuro; Morishima, Toshitaka; Iwata, Satomi; Kaneko, Takeshi; Yanagawa, Yuchio; Yoshida, Sachiko; Fukuda, Atsuo

    2014-04-01

    Although focal cortical malformations are considered neuronal migration disorders, their formation mechanisms remain unknown. We addressed how the γ-aminobutyric acid (GABA)ergic system affects the GABAergic and glutamatergic neuronal migration underlying such malformations. A focal freeze-lesion (FFL) of the postnatal day zero (P0) glutamic acid decarboxylase-green fluorescent protein knock-in mouse neocortex produced a 3- or 4-layered microgyrus at P7. GABAergic interneurons accumulated around the necrosis including the superficial region during microgyrus formation at P4, whereas E17.5-born, Cux1-positive pyramidal neurons outlined the GABAergic neurons and were absent from the superficial layer, forming cell-dense areas in layer 2 of the P7 microgyrus. GABA imaging showed that an extracellular GABA level temporally increased in the GABAergic neuron-positive area, including the necrotic center, at P4. The expression of the Cl(-) transporter KCC2 was downregulated in the microgyrus-forming GABAergic and E17.5-born glutamatergic neurons at P4; these cells may need a high intracellular Cl(-) concentration to induce depolarizing GABA effects. Bicuculline decreased the frequency of spontaneous Ca(2+) oscillations in these microgyrus-forming cells. Thus, neonatal FFL causes specific neuronal accumulation, preceded by an increase in ambient GABA during microgyrus formation. This GABA increase induces GABAA receptor-mediated Ca(2+) oscillation in KCC2-downregulated microgyrus-forming cells, as seen in migrating cells during early neocortical development.

  1. Hyperexcitable neurons and altered non-neuronal cells in the compressed spinal ganglion

    PubMed Central

    LaMotte, Robert H.; Chao, MA

    2009-01-01

    The cell body or soma in the dosal root ganglion (DRG) is normally excitable and this excitability can increase and persist after an injury of peripheral sensory neurons. In a rat model of radicular pain, an intraforaminal implantation of a rod that chronically compressed the lumbar DRG (“CCD” model) resulted in neuronal somal hyperexcitability and spontaneous activity that was accompanied by hyperalgesia in the ipsilateral hind paw. By the 5th day after onset of CCD, there was a novel upregulation in neuronal expression of the chemokine, monocyte chemoattractant protein-1 (MCP-1 or CCL2) and also its receptor, CCR2. The neurons developed, in response to topically applied MCP-1, an excitatory response that they normally do not have. CCD also activated non-neuronal cells including, for example, the endothelial cells as evidenced by angiogenesis in the form of an increased number of capillaries in the DRG after 7 days. A working hypothesis is that the CCD induced changes in neurons and non-neuronal cells that may act together to promote the survival of the injured tissue. The release of ligands such as CCL2, in addition to possibly activating nociceptive neurons (maintaining the pain), may also act to preserve injured cells in the face of ischemia and hypoxia, for example, by promoting angiogenesis. Thus, somal hyperexcitability, as often said of inflammation, may represent a double edged sword. PMID:18958366

  2. Callosally projecting neurons in the macaque monkey V1/V2 border are enriched in nonphosphorylated neurofilament protein

    NASA Technical Reports Server (NTRS)

    Hof, P. R.; Ungerleider, L. G.; Adams, M. M.; Webster, M. J.; Gattass, R.; Blumberg, D. M.; Morrison, J. H.; Bloom, F. E. (Principal Investigator)

    1997-01-01

    Previous immunohistochemical studies combined with retrograde tracing in macaque monkeys have demonstrated that corticocortical projections can be differentiated by their content of neurofilament protein. The present study analyzed the distribution of nonphosphorylated neurofilament protein in callosally projecting neurons located at the V1/V2 border. All of the retrogradely labeled neurons were located in layer III at the V1/V2 border and at an immediately adjacent zone of area V2. A quantitative analysis showed that the vast majority (almost 95%) of these interhemispheric projection neurons contain neurofilament protein immunoreactivity. This observation differs from data obtained in other sets of callosal connections, including homotypical interhemispheric projections in the prefrontal, temporal, and parietal association cortices, that were found to contain uniformly low proportions of neurofilament protein-immunoreactive neurons. Comparably, highly variable proportions of neurofilament protein-containing neurons have been reported in intrahemispheric corticocortical pathways, including feedforward and feedback visual connections. These results indicate that neurofilament protein is a prominent neurochemical feature that identifies a particular population of interhemispheric projection neurons at the V1/V2 border and suggest that this biochemical attribute may be critical for the function of this subset of callosal neurons.

  3. Early Monocular Defocus Disrupts the Normal Development of Receptive-Field Structure in V2 Neurons of Macaque Monkeys

    PubMed Central

    Tao, Xiaofeng; Zhang, Bin; Shen, Guofu; Wensveen, Janice; Smith, Earl L.; Nishimoto, Shinji; Ohzawa, Izumi

    2014-01-01

    Experiencing different quality images in the two eyes soon after birth can cause amblyopia, a developmental vision disorder. Amblyopic humans show the reduced capacity for judging the relative position of a visual target in reference to nearby stimulus elements (position uncertainty) and often experience visual image distortion. Although abnormal pooling of local stimulus information by neurons beyond striate cortex (V1) is often suggested as a neural basis of these deficits, extrastriate neurons in the amblyopic brain have rarely been studied using microelectrode recording methods. The receptive field (RF) of neurons in visual area V2 in normal monkeys is made up of multiple subfields that are thought to reflect V1 inputs and are capable of encoding the spatial relationship between local stimulus features. We created primate models of anisometropic amblyopia and analyzed the RF subfield maps for multiple nearby V2 neurons of anesthetized monkeys by using dynamic two-dimensional noise stimuli and reverse correlation methods. Unlike in normal monkeys, the subfield maps of V2 neurons in amblyopic monkeys were severely disorganized: subfield maps showed higher heterogeneity within each neuron as well as across nearby neurons. Amblyopic V2 neurons exhibited robust binocular suppression and the strength of the suppression was positively correlated with the degree of hereogeneity and the severity of amblyopia in individual monkeys. Our results suggest that the disorganized subfield maps and robust binocular suppression of amblyopic V2 neurons are likely to adversely affect the higher stages of cortical processing resulting in position uncertainty and image distortion. PMID:25297110

  4. Novel model of neuronal bioenergetics: postsynaptic utilization of glucose but not lactate correlates positively with Ca2+ signalling in cultured mouse glutamatergic neurons.

    PubMed

    Bak, Lasse K; Obel, Linea F; Walls, Anne B; Schousboe, Arne; Faek, Sevan A A; Jajo, Farah S; Waagepetersen, Helle S

    2012-04-05

    We have previously investigated the relative roles of extracellular glucose and lactate as fuels for glutamatergic neurons during synaptic activity. The conclusion from these studies was that cultured glutamatergic neurons utilize glucose rather than lactate during NMDA (N-methyl-d-aspartate)-induced synaptic activity and that lactate alone is not able to support neurotransmitter glutamate homoeostasis. Subsequently, a model was proposed to explain these results at the cellular level. In brief, the intermittent rises in intracellular Ca2+ during activation cause influx of Ca2+ into the mitochondrial matrix thus activating the tricarboxylic acid cycle dehydrogenases. This will lead to a lower activity of the MASH (malate-aspartate shuttle), which in turn will result in anaerobic glycolysis and lactate production rather than lactate utilization. In the present work, we have investigated the effect of an ionomycin-induced increase in intracellular Ca2+ (i.e. independent of synaptic activity) on neuronal energy metabolism employing 13C-labelled glucose and lactate and subsequent mass spectrometric analysis of labelling in glutamate, alanine and lactate. The results demonstrate that glucose utilization is positively correlated with intracellular Ca2+ whereas lactate utilization is not. This result lends further support for a significant role of glucose in neuronal bioenergetics and that Ca2+ signalling may control the switch between glucose and lactate utilization during synaptic activity. Based on the results, we propose a compartmentalized CiMASH (Ca2+-induced limitation of the MASH) model that includes intracellular compartmentation of glucose and lactate metabolism. We define pre- and post-synaptic compartments metabolizing glucose and glucose plus lactate respectively in which the latter displays a positive correlation between oxidative metabolism of glucose and Ca2+ signalling.

  5. Environmental CO2 inhibits Caenorhabditis elegans egg-laying by modulating olfactory neurons and evokes widespread changes in neural activity

    PubMed Central

    Fenk, Lorenz A.; de Bono, Mario

    2015-01-01

    Carbon dioxide (CO2) gradients are ubiquitous and provide animals with information about their environment, such as the potential presence of prey or predators. The nematode Caenorhabditis elegans avoids elevated CO2, and previous work identified three neuron pairs called “BAG,” “AFD,” and “ASE” that respond to CO2 stimuli. Using in vivo Ca2+ imaging and behavioral analysis, we show that C. elegans can detect CO2 independently of these sensory pathways. Many of the C. elegans sensory neurons we examined, including the AWC olfactory neurons, the ASJ and ASK gustatory neurons, and the ASH and ADL nociceptors, respond to a rise in CO2 with a rise in Ca2+. In contrast, glial sheath cells harboring the sensory endings of C. elegans’ major chemosensory neurons exhibit strong and sustained decreases in Ca2+ in response to high CO2. Some of these CO2 responses appear to be cell intrinsic. Worms therefore may couple detection of CO2 to that of other cues at the earliest stages of sensory processing. We show that C. elegans persistently suppresses oviposition at high CO2. Hermaphrodite-specific neurons (HSNs), the executive neurons driving egg-laying, are tonically inhibited when CO2 is elevated. CO2 modulates the egg-laying system partly through the AWC olfactory neurons: High CO2 tonically activates AWC by a cGMP-dependent mechanism, and AWC output inhibits the HSNs. Our work shows that CO2 is a more complex sensory cue for C. elegans than previously thought, both in terms of behavior and neural circuitry. PMID:26100886

  6. Diversity of glycosphingolipid GM2 and cholesterol accumulation in NPC1 patient-specific iPSC-derived neurons.

    PubMed

    Trilck, Michaela; Peter, Franziska; Zheng, Chaonan; Frank, Marcus; Dobrenis, Kostantin; Mascher, Hermann; Rolfs, Arndt; Frech, Moritz J

    2017-02-15

    Niemann-Pick disease Type C1 (NPC1) is a rare progressive neurodegenerative disorder caused by mutations in the NPC1 gene. On the cellular level NPC1 mutations lead to an accumulation of cholesterol and gangliosides. As a thorough analysis of the severely affected neuronal cells is unfeasible in NPC1 patients, we recently described the cellular phenotype of neuronal cells derived from NPC1 patient iPSCs carrying the compound heterozygous mutation c.1836A>C/c.1628delC. Here we expanded the analysis to cell lines carrying the prevalent mutation c.3182T>C and the novel mutation c.1180T>C, as well as to the determination of GM2 and GM3 gangliosides in NPC1 patient-specific iPSC-derived neurons and glia cells. Immunocytochemical detection of GM2 revealed punctated staining pattern predominantly localized in neurons. Detection of cholesterol by filipin staining showed a comparable staining pattern, colocalized with GM2, indicating a deposit of GM2 and cholesterol in the same cellular compartments. Accumulations were not only restricted to cell bodies, but were also found in the neuronal extensions. A quantification of the GM2 amount by HPLC-MS/MS confirmed significantly higher amounts in neurons carrying a mutation. Additionally, these cells displayed a lowered activity of the catabolic enzyme Hex A, but not B4GALNT1. Molecular docking simulations indicated binding of cholesterol to Hex A, suggesting cholesterol influences the GM2 degradation pathway and, subsequently, leading to the accumulation of GM2. Taken together, this is the first study showing an accumulation of GM2 in neuronal derivatives of patient-specific iPSCs and thus proving further disease-specific hallmarks in this human in vitro model of NPC1. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Modulation of 3H-noradrenaline release by presynaptic opioid, cannabinoid and bradykinin receptors and β-adrenoceptors in mouse tissues

    PubMed Central

    Trendelenburg, A U; Cox, S L; Schelb, V; Klebroff, W; Khairallah, L; Starke, K

    2000-01-01

    Release-modulating opioid and cannabinoid (CB) receptors, β-adrenoceptors and bradykinin receptors at noradrenergic axons were studied in mouse tissues (occipito-parietal cortex, heart atria, vas deferens and spleen) preincubated with 3H-noradrenaline. Experiments using the OP1 receptor-selective agonists DPDPE and DSLET, the OP2-selective agonists U50488H and U69593, the OP3-selective agonist DAMGO, the ORL1 receptor-selective agonist nociceptin, and a number of selective antagonists showed that the noradrenergic axons innervating the occipito-parietal cortex possess release-inhibiting OP3 and ORL1 receptors, those innervating atria OP1, ORL1 and possibly OP3 receptors, and those innervating the vas deferens all four opioid receptor types. Experiments using the non-selective CB agonists WIN 55,212-2 and CP 55,940 and the CB1-selective antagonist SR 141716A indicated that the noradrenergic axons of the vas deferens possess release-inhibiting CB1 receptors. Presynaptic CB receptors were not found in the occipito-parietal cortex, in atria or in the spleen. Experiments using the non-selective β-adrenoceptor agonist isoprenaline and the β2-selective agonist salbutamol, as well as subtype-selective antagonists, demonstrated the occurrence of release-enhancing β2-adrenoceptors at the sympathetic axons of atria and the spleen, but demonstrated their absence in the occipito-parietal cortex and the vas deferens. Experiments with bradykinin and the B2-selective antagonist Hoe 140 showed the operation of release-enhancing B2 receptors at the sympathetic axons of atria, the vas deferens and the spleen, but showed their absence in the occipito-parietal cortex. The experiments document a number of new presynaptic receptor locations. They confirm and extend the existence of marked tissue and species differences in presynaptic receptors at noradrenergic neurons. PMID:10807669

  8. Selective nitrergic neurodegeneration in diabetes mellitus–a nitric oxide-dependent phenomenon

    PubMed Central

    Cellek, Selim; Rodrigo, José; Lobos, Edgar; Fernández, Patricia; Serrano, Julia; Moncada, Salvador

    1999-01-01

    In vitro and in vivo studies have demonstrated a dysfunctional nitrergic system in diabetes mellitus, thus explaining the origin of diabetic impotence. However, the mechanism of this nitrergic defect is not understood.In the penises of streptozotocin (STZ)-induced diabetic rats, here, we show by immunohistochemistry that nitrergic nerves undergo selective degeneration since the noradrenergic nerves which have an anti-erectile function in the penis remained intact.Nitrergic relaxation responses in vitro and erectile responses to cavernous nerve stimulation in vivo were attenuated in these animals, whereas noradrenergic responses were enhanced.Activity and protein amount of neuronal nitric oxide synthase (nNOS) were also reduced in the penile tissue of diabetic rats.We, thus, hypothesized that NO in the nitrergic nerves may be involved in the nitrergic nerve damage, since only the nerves which contain neuronal NO synthase underwent degeneration.We administered an inhibitor of NO synthase, NG-nitro-L-arginine methyl ester (L-NAME), in the drinking water of rats for up to 12 weeks following the establishment of diabetes with STZ.Here we demonstrate that this compound protected the nitrergic nerves from morphological and functional impairment. Our results show that selective nitrergic degeneration in diabetes is NO-dependent and suggest that inhibition of NO synthase is neuroprotective in this condition. PMID:10588937

  9. Calcium-calmodulin-dependent kinase II modulates Kv4.2 channel expression and upregulates neuronal A-type potassium currents.

    PubMed

    Varga, Andrew W; Yuan, Li-Lian; Anderson, Anne E; Schrader, Laura A; Wu, Gang-Yi; Gatchel, Jennifer R; Johnston, Daniel; Sweatt, J David

    2004-04-07

    Calcium-calmodulin-dependent kinase II (CaMKII) has a long history of involvement in synaptic plasticity, yet little focus has been given to potassium channels as CaMKII targets despite their importance in repolarizing EPSPs and action potentials and regulating neuronal membrane excitability. We now show that Kv4.2 acts as a substrate for CaMKII in vitro and have identified CaMKII phosphorylation sites as Ser438 and Ser459. To test whether CaMKII phosphorylation of Kv4.2 affects channel biophysics, we expressed wild-type or mutant Kv4.2 and the K(+) channel interacting protein, KChIP3, with or without a constitutively active form of CaMKII in Xenopus oocytes and measured the voltage dependence of activation and inactivation in each of these conditions. CaMKII phosphorylation had no effect on channel biophysical properties. However, we found that levels of Kv4.2 protein are increased with CaMKII phosphorylation in transfected COS cells, an effect attributable to direct channel phosphorylation based on site-directed mutagenesis studies. We also obtained corroborating physiological data showing increased surface A-type channel expression as revealed by increases in peak K(+) current amplitudes with CaMKII phosphorylation. Furthermore, endogenous A-currents in hippocampal pyramidal neurons were increased in amplitude after introduction of constitutively active CaMKII, which results in a decrease in neuronal excitability in response to current injections. Thus CaMKII can directly modulate neuronal excitability by increasing cell-surface expression of A-type K(+) channels.

  10. Noradrenergic and cholinergic innervation of the bone marrow.

    PubMed

    Artico, Marco; Bosco, Sandro; Cavallotti, Carlo; Agostinelli, Enzo; Giuliani-Piccari, Gabriella; Sciorio, Salvatore; Cocco, Lucio; Vitale, Marco

    2002-07-01

    Bone marrow is supplied by sensory and autonomic innervation. Although it is well established that hematopoiesis is regulated by cytokines and cell-to-cell contacts, the role played by neuromediators on the proliferation, differentiation and release of hematopoietic cells is still controversial. We studied the innervation of rat femur bone marrow by means of fluorescence histochemistry and immunohistochemistry. Glyoxylic acid-induced fluorescence was used to demonstrate catecholaminergic nerve fibers. The immunoperoxidase method with nickel amplification was applied to detect the distribution of nerve fibers using antibodies against the general neuronal marker PGP 9.5 (neuron-specific cytoplasmic protein), while the cholinacetyltransferase immunoreactivity was studied by immunohistochemistry. Our results show the presence of an extensive network of innervation in the rat bone marrow, providing a morphological basis for the neural modulation of hemopoiesis.

  11. Distribution of voltage-dependent and intracellular Ca2+ channels in submucosal neurons from rat distal colon.

    PubMed

    Rehn, Matthias; Bader, Sandra; Bell, Anna; Diener, Martin

    2013-09-01

    We recently observed a bradykinin-induced increase in the cytosolic Ca2+ concentration in submucosal neurons of rat colon, an increase inhibited by blockers of voltage-dependent Ca2+ (Ca(v)) channels. As the types of Ca(v) channels used by this part of the enteric nervous system are unknown, the expression of various Ca(v) subunits has been investigated in whole-mount submucosal preparations by immunohistochemistry. Submucosal neurons, identified by a neuronal marker (microtubule-associated protein 2), are immunoreactive for Ca(v)1.2, Ca(v)1.3 and Ca(v)2.2, expression being confirmed by reverse transcription plus the polymerase chain reaction. These data agree with previous observations that the inhibition of L- and N-type Ca2+ currents strongly inhibits the response to bradykinin. However, whole-cell patch-clamp experiments have revealed that bradykinin does not enhance Ca2+ inward currents under voltage-clamp conditions. Consequently, bradykinin does not directly interact with Ca(v) channels. Instead, the kinin-induced Ca2+ influx is caused indirectly by the membrane depolarization evoked by this peptide. As intracellular Ca2+ channels on Ca(2+)-storing organelles can also contribute to Ca2+ signaling, their expression has been investigated by imaging experiments and immunohistochemistry. Inositol 1,4,5-trisphosphate (IP3) receptors (IP3R) have been functionally demonstrated in submucosal neurons loaded with the Ca(2+)-sensitive fluorescent dye, fura-2. Histamine, a typical agonist coupled to the phospholipase C pathway, induces an increase in the fura-2 signal ratio, which is suppressed by 2-aminophenylborate, a blocker of IP3 receptors. The expression of IP3R1 has been confirmed by immunohistochemistry. In contrast, ryanodine, tested over a wide concentration range, evokes no increase in the cytosolic Ca2+ concentration nor is there immunohistochemical evidence for the expression of ryanodine receptors in these neurons. Thus, rat submucosal neurons are equipped

  12. Establishment of a long-term primary culture of striatal neurons.

    PubMed

    Sebben, M; Gabrion, J; Manzoni, O; Sladeczek, F; Gril, C; Bockaert, J; Dumuis, A

    1990-03-01

    A new method of obtaining long-term primary cultures (lasting more than 8 weeks) of striatal neurons is described in this paper. The originality of the method consists of: (1) starting the culture for 3 days in a serum-free medium which allows attachment and neurite proliferation of neurons as well as the death of non-neuronal cells (mainly consisting of astrocytes); (2) introducing a limited amount of fetal calf serum (FCS) (2-5%) after 3 days in vitro (3 DIV), which likely provides optimal neuronal survival and attachment factors, and a limited amount of astrocyte proliferating factors. The period of introduction of serum, as well as the amount of serum introduced are critical factors. By phase contrast and transmission electron microscopy, we observed that neurons continued to develop neurite extensions, synaptic vesicles and synapse formations up to 50 DIV. Neuronal membranes, and synaptic contacts were particularly healthy up to 50 DIV. Interestingly, the number of astrocytes was constant between 30-50 DIV and limited to about 10%. We therefore obtained an equilibrium between neuronal and astrocyte differentiation and proliferation. It is likely that the small population of astrocytes, plus the low percentage of FCS added, provide essential factors for neuronal survival and differentiation, whereas a high density of differentiated neurons inhibited astrocyte cell proliferation. The clear-cut stability of these neuronal cultures goes in parallel with the stability of the pharmacological responses studied here: the coupling of carbachol and quisqualate receptors with the inositol phosphate production system. The culture method described here could be of particular interest to pursue biochemical, pharmacological and biological studies on neurons as well as on reciprocal interactions between neurons and astrocytes.

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

    PubMed Central

    Herculano-Houzel, Suzana

    2011-01-01

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

  14. 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.

  15. Tissue Inhibitor of Metalloproteinase-2 promotes neuronal differentiation by acting as an anti-mitogenic signal

    PubMed Central

    Pérez-Martínez, Leonor; Jaworski, Diane M.

    2005-01-01

    Although traditionally recognized for maintaining extracellular matrix integrity during morphogenesis, the function of matrix metalloproteinases (MMPs) and their inhibitors, the tissue inhibitors of metalloproteinases (TIMPs), in the mature nervous system is largely unknown. Here, we report that TIMP-2 induces PC12 cell cycle arrest via regulation of cell cycle regulatory proteins resulting in differentiation and neurite outgrowth. TIMP-2 decreases cyclin B and D expression and increases p21Cip expression. Furthermore, TIMP-2 promotes cell differentiation via activation of the cAMP/Rap1/ERK pathway. Expression of dominant negative Rap1 blocks TIMP-2 mediated neurite outgrowth. Both the cell cycle arrest and neurite outgrowth induced by TIMP-2 was independent of MMP inhibitory activity. Consistent with the PC12 cell data, primary cultures of TIMP-2 knockout cerebral cortical neurons exhibit significantly reduced neurite length, which is rescued by TIMP-2. These in vitro results were corroborated in vivo. TIMP-2 deletion causes a delay in neuronal differentiation as demonstrated by the persistence of nestin-positive progenitors in the neocortical ventricular zone. The interaction of TIMP-2 with α3β1 integrin in the cerebral cortex suggests that TIMP-2 promotes neuronal differentiation and maintains mitotic quiescence in an MMP independent manner through integrin activation. The identification of molecules responsible for neuronal quiescence has significant implications for the adult brain’s ability to generate new neurons in response to injury and neurological disorders such as Alzheimer’s and Parkinson’s disease. PMID:15901773

  16. Life-long stability of neurons: a century of research on neurogenesis, neuronal death and neuron quantification in adult CNS.

    PubMed

    Turlejski, Kris; Djavadian, Ruzanna

    2002-01-01

    In this chapter we provide an extensive review of 100 years of research on the stability of neurons in the mammalian brain, with special emphasis on humans. Although Cajal formulated the Neuronal Doctrine, he was wrong in his beliefs that adult neurogenesis did not occur and adult neurons are dying throughout life. These two beliefs became accepted "common knowledge" and have shaped much of neuroscience research and provided much of the basis for clinical treatment of age-related brain diseases. In this review, we consider adult neurogenesis from a historical and evolutionary perspective. It is concluded, that while adult neurogenesis is a factor in the dynamics of the dentate gyrus and olfactory bulb, it is probably not a major factor during the life-span in most brain areas. Likewise, the acceptance of neuronal death as an explanation for normal age-related senility is challenged with evidence collected over the last fifty years. Much of the problem in changing this common belief of dying neurons was the inadequacies of neuronal counting methods. In this review we discuss in detail implications of recent improvements in neuronal quantification. We conclude: First, age-related neuronal atrophy is the major factor in functional deterioration of existing neurons and could be slowed down, or even reversed by various pharmacological interventions. Second, in most cases neuronal degeneration during aging is a pathology that in principle may be avoided. Third, loss of myelin and of the white matter is more frequent and important than the limited neuronal death in normal aging.

  17. Characterization of an extracellular epitope antibody to the neuronal K-Cl cotransporter, KCC2.

    PubMed

    Gagnon, Kenneth Be; Fyffe, Robert Ew; Adragna, Norma C; Lauf, Peter K

    2007-07-01

    1. Ion gradients across the cell membrane are important for proper cellular communication and homeostasis. With the exception of erythrocytes, chloride (Cl), one of the most important free anions in animal cells, is not distributed at thermodynamic equilibrium across the plasma membrane. The K-Cl cotransporter (COT), consisting of at least four isoforms, utilizes the larger outwardly directed chemical driving force of K to expel Cl from the cell against its inwardly directed chemical gradient and has been implicated recently as one of the main Cl extruders in developing neurons. 2. Previous in situ hybridization studies have indicated widespread mRNA distribution of the neuronal-specific K-Cl COT isoform (KCC2) throughout the rat central nervous system (CNS). However, immunohistochemical studies have been limited owing to the availability of a more selective antibody to KCC2. The goal of the present study was to develop a new molecular tool for the immunohistochemical identification and neuronal distribution of KCC2. 3. Herein, we present evidence of immunohistochemical corroboration of the widespread KCC2 mRNA expression using a novel extracellular anti-peptide antibody directed against the second extracellular loop (ECL2) of KCC2. Immunoperoxidase and immunofluorescent labelling revealed widespread post-synaptic somatic and dendritic localization of KCC2 in multiple neuronal populations in the cerebral cortex, hippocampus, brainstem, lumbar spinal cord and cerebellum. We also demonstrate that binding of the antibody to an extracellular epitope within ECL2 does not alter cotransporter function. In essence, the present study reports on a new molecular tool for structural and functional studies of KCC2.

  18. Sphingosine-1-Phosphate and the S1P3 Receptor Initiate Neuronal Retraction via RhoA/ROCK Associated with CRMP2 Phosphorylation.

    PubMed

    Quarta, Serena; Camprubí-Robles, Maria; Schweigreiter, Rüdiger; Matusica, Dusan; Haberberger, Rainer V; Proia, Richard L; Bandtlow, Christine E; Ferrer-Montiel, Antonio; Kress, Michaela

    2017-01-01

    The bioactive lipid sphingosine-1-phosphate (S1P) is an important regulator in the nervous system. Here, we explored the role of S1P and its receptors in vitro and in preclinical models of peripheral nerve regeneration. Adult sensory neurons and motor neuron-like cells were exposed to S1P in an in vitro assay, and virtually all neurons responded with a rapid retraction of neurites and growth cone collapse which were associated with RhoA and ROCK activation. The S1P 1 receptor agonist SEW2871 neither activated RhoA or neurite retraction, nor was S1P-induced neurite retraction mitigated in S1P 1 -deficient neurons. Depletion of S1P 3 receptors however resulted in a dramatic inhibition of S1P-induced neurite retraction and was on the contrary associated with a significant elongation of neuronal processes in response to S1P. Opposing responses to S1P could be observed in the same neuron population, where S1P could activate S1P 1 receptors to stimulate elongation or S1P 3 receptors and retraction. S1P was, for the first time in sensory neurons, linked to the phosphorylation of collapsin response-mediated protein-2 (CRMP2), which was inhibited by ROCK inhibition. The improved sensory recovery after crush injury further supported the relevance of a critical role for S1P and receptors in fine-tuning axonal outgrowth in peripheral neurons.

  19. Dissociable roles of glucocorticoid and noradrenergic activation on social discounting.

    PubMed

    Margittai, Zsofia; van Wingerden, Marijn; Schnitzler, Alfons; Joëls, Marian; Kalenscher, Tobias

    2018-04-01

    People often exhibit prosocial tendencies towards close kin and friends, but generosity decreases as a function of increasing social distance between donor and recipient, a phenomenon called social discounting. Evidence suggests that acute stress affects prosocial behaviour in general and social discounting in particular. We tested the causal role of the important stress neuromodulators cortisol (CORT) and noradrenaline (NA) in this effect by considering two competing hypotheses. On the one hand, it is possible that CORT and NA act in concert to increase generosity towards socially close others by reducing the aversiveness of the cost component in costly altruism and enhancing the emotional salience of vicarious reward. Alternatively, it is equally plausible that CORT and NA exert dissociable, opposing effects on prosocial behaviour based on prior findings implicating CORT in social affiliation, and NA in aggressive and antagonistic tendencies. We pharmacologically manipulated CORT and NA levels in a sample of men (N = 150) and found that isolated hydrocortisone administration promoted prosocial tendencies towards close others, reflected in an altered social discount function, but this effect was offset by concurrent noradrenergic activation brought about by simultaneous yohimbine administration. These results provide inceptive evidence for causal, opposing roles of these two important stress neuromodulators on prosocial behaviour, and give rise to the possibility that, depending on the neuroendocrine response profile, stress neuromodulator action can foster both tend-and-befriend and fight-or-flight tendencies at the same time. Copyright © 2018 Elsevier Ltd. All rights reserved.

  20. Atp13a2-deficient mice exhibit neuronal ceroid lipofuscinosis, limited α-synuclein accumulation and age-dependent sensorimotor deficits

    PubMed Central

    Schultheis, Patrick J.; Fleming, Sheila M.; Clippinger, Amy K.; Lewis, Jada; Tsunemi, Taiji; Giasson, Benoit; Dickson, Dennis W.; Mazzulli, Joseph R.; Bardgett, Mark E.; Haik, Kristi L.; Ekhator, Osunde; Chava, Anil Kumar; Howard, John; Gannon, Matt; Hoffman, Elizabeth; Chen, Yinhuai; Prasad, Vikram; Linn, Stephen C.; Tamargo, Rafael J.; Westbroek, Wendy; Sidransky, Ellen; Krainc, Dimitri; Shull, Gary E.

    2013-01-01

    Mutations in ATP13A2 (PARK9), encoding a lysosomal P-type ATPase, are associated with both Kufor–Rakeb syndrome (KRS) and neuronal ceroid lipofuscinosis (NCL). KRS has recently been classified as a rare genetic form of Parkinson's disease (PD), whereas NCL is a lysosomal storage disorder. Although the transport activity of ATP13A2 has not been defined, in vitro studies show that its loss compromises lysosomal function, which in turn is thought to cause neuronal degeneration. To understand the role of ATP13A2 dysfunction in disease, we disrupted its gene in mice. Atp13a2−/− and Atp13a2+/+ mice were tested behaviorally to assess sensorimotor and cognitive function at multiple ages. In the brain, lipofuscin accumulation, α-synuclein aggregation and dopaminergic pathology were measured. Behaviorally, Atp13a2−/− mice displayed late-onset sensorimotor deficits. Accelerated deposition of autofluorescent storage material (lipofuscin) was observed in the cerebellum and in neurons of the hippocampus and the cortex of Atp13a2−/− mice. Immunoblot analysis showed increased insoluble α-synuclein in the hippocampus, but not in the cortex or cerebellum. There was no change in the number of dopaminergic neurons in the substantia nigra or in striatal dopamine levels in aged Atp13a2−/− mice. These results show that the loss of Atp13a2 causes sensorimotor impairments, α-synuclein accumulation as occurs in PD and related synucleinopathies, and accumulation of lipofuscin deposits characteristic of NCL, thus providing the first direct demonstration that null mutations in Atp13a2 can cause pathological features of both diseases in the same organism. PMID:23393156