1
|
Brunetti V, Soda T, Berra-Romani R, De Sarro G, Guerra G, Scarpellino G, Moccia F. Two Signaling Modes Are Better than One: Flux-Independent Signaling by Ionotropic Glutamate Receptors Is Coming of Age. Biomedicines 2024; 12:880. [PMID: 38672234 PMCID: PMC11048239 DOI: 10.3390/biomedicines12040880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2024] [Revised: 04/02/2024] [Accepted: 04/12/2024] [Indexed: 04/28/2024] Open
Abstract
Glutamate is the major excitatory neurotransmitter in the central nervous system. Glutamatergic transmission can be mediated by ionotropic glutamate receptors (iGluRs), which mediate rapid synaptic depolarization that can be associated with Ca2+ entry and activity-dependent change in the strength of synaptic transmission, as well as by metabotropic glutamate receptors (mGluRs), which mediate slower postsynaptic responses through the recruitment of second messenger systems. A wealth of evidence reported over the last three decades has shown that this dogmatic subdivision between iGluRs and mGluRs may not reflect the actual physiological signaling mode of the iGluRs, i.e., α-amino-3-hydroxy-5-methyl-4-isoxasolepropionic acid (AMPA) receptors (AMPAR), kainate receptors (KARs), and N-methyl-D-aspartate (NMDA) receptors (NMDARs). Herein, we review the evidence available supporting the notion that the canonical iGluRs can recruit flux-independent signaling pathways not only in neurons, but also in brain astrocytes and cerebrovascular endothelial cells. Understanding the signaling versatility of iGluRs can exert a profound impact on our understanding of glutamatergic synapses. Furthermore, it may shed light on novel neuroprotective strategies against brain disorders.
Collapse
Affiliation(s)
- Valentina Brunetti
- Laboratory of General Physiology, Department of Biology and Biotechnology “L. Spallanzani”, 27110 Pavia, Italy; (V.B.); (G.S.)
| | - Teresa Soda
- Department of Health Sciences, School of Medicine and Surgery, Magna Graecia University of Catanzaro, 88100 Catanzaro, Italy; (T.S.); (G.D.S.)
| | - Roberto Berra-Romani
- Department of Biomedicine, School of Medicine, Benemérita Universidad Autónoma de Puebla, Puebla 72410, Mexico;
| | - Giovambattista De Sarro
- Department of Health Sciences, School of Medicine and Surgery, Magna Graecia University of Catanzaro, 88100 Catanzaro, Italy; (T.S.); (G.D.S.)
- System and Applied Pharmacology@University Magna Grecia, Science of Health Department, School of Medicine, Magna Graecia University of Catanzaro, 88110 Catanzaro, Italy
| | - Germano Guerra
- Department of Medicine and Health Science “Vincenzo Tiberio”, School of Medicine and Surgery, University of Molise, 86100 Campobasso, Italy;
| | - Giorgia Scarpellino
- Laboratory of General Physiology, Department of Biology and Biotechnology “L. Spallanzani”, 27110 Pavia, Italy; (V.B.); (G.S.)
| | - Francesco Moccia
- Department of Medicine and Health Science “Vincenzo Tiberio”, School of Medicine and Surgery, University of Molise, 86100 Campobasso, Italy;
| |
Collapse
|
2
|
Nomura T, Taniguchi S, Wang YZ, Yeh NH, Wilen AP, Castillon CCM, Foote KM, Xu J, Armstrong JN, Savas JN, Swanson GT, Contractor A. A Pathogenic Missense Mutation in Kainate Receptors Elevates Dendritic Excitability and Synaptic Integration through Dysregulation of SK Channels. J Neurosci 2023; 43:7913-7928. [PMID: 37802657 PMCID: PMC10669804 DOI: 10.1523/jneurosci.1259-23.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 09/12/2023] [Accepted: 09/16/2023] [Indexed: 10/08/2023] Open
Abstract
Numerous rare variants that cause neurodevelopmental disorders (NDDs) occur within genes encoding synaptic proteins, including ionotropic glutamate receptors. However, in many cases, it remains unclear how damaging missense variants affect brain function. We determined the physiological consequences of an NDD causing missense mutation in the GRIK2 kainate receptor (KAR) gene, that results in a single amino acid change p.Ala657Thr in the GluK2 receptor subunit. We engineered this mutation in the mouse Grik2 gene, yielding a GluK2(A657T) mouse, and studied mice of both sexes to determine how hippocampal neuronal function is disrupted. Synaptic KAR currents in hippocampal CA3 pyramidal neurons from heterozygous A657T mice exhibited slow decay kinetics, consistent with incorporation of the mutant subunit into functional receptors. Unexpectedly, CA3 neurons demonstrated elevated action potential spiking because of downregulation of the small-conductance Ca2+ activated K+ channel (SK), which mediates the post-spike afterhyperpolarization. The reduction in SK activity resulted in increased CA3 dendritic excitability, increased EPSP-spike coupling, and lowered the threshold for the induction of LTP of the associational-commissural synapses in CA3 neurons. Pharmacological inhibition of SK channels in WT mice increased dendritic excitability and EPSP-spike coupling, mimicking the phenotype in A657T mice and suggesting a causative role for attenuated SK activity in aberrant excitability observed in the mutant mice. These findings demonstrate that a disease-associated missense mutation in GRIK2 leads to altered signaling through neuronal KARs, pleiotropic effects on neuronal and dendritic excitability, and implicate these processes in neuropathology in patients with genetic NDDs.SIGNIFICANCE STATEMENT Damaging mutations in genes encoding synaptic proteins have been identified in various neurodevelopmental disorders, but the functional consequences at the cellular and circuit level remain elusive. By generating a novel knock-in mutant mouse, this study examined the role of a pathogenic mutation in the GluK2 kainate receptor (KAR) subunit, a subclass of ionotropic glutamate receptors. Analyses of hippocampal CA3 pyramidal neurons determined elevated action potential firing because of an increase in dendritic excitability. Increased dendritic excitability was attributable to reduced activity of a Ca2+ activated K+ channel. These results indicate that a pathogenic KAR mutation results in dysregulation of dendritic K+ channels, which leads to an increase in synaptic integration and backpropagation of action potentials into distal dendrites.
Collapse
Affiliation(s)
- Toshihiro Nomura
- Department of Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
| | - Sakiko Taniguchi
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
| | - Yi-Zhi Wang
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
| | - Nai-Hsing Yeh
- Department of Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
| | - Anika P Wilen
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
| | - Charlotte C M Castillon
- Department of Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
| | - Kendall M Foote
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
| | - Jian Xu
- Department of Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
| | - John N Armstrong
- Department of Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
| | - Jeffrey N Savas
- Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
| | - Geoffrey T Swanson
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
- Department of Neurobiology, Weinberg College of Arts and Sciences Northwestern University, Chicago, Illinois 60611
| | - Anis Contractor
- Department of Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
- Department of Psychiatry and Behavioral Sciences Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
- Department of Neurobiology, Weinberg College of Arts and Sciences Northwestern University, Chicago, Illinois 60611
| |
Collapse
|
3
|
Nair JD, Wilkinson KA, Yucel BP, Mulle C, Vissel B, Mellor J, Henley JM. GluK2 Q/R editing regulates kainate receptor signaling and long-term potentiation of AMPA receptors. iScience 2023; 26:107708. [PMID: 37720087 PMCID: PMC10504484 DOI: 10.1016/j.isci.2023.107708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 07/18/2023] [Accepted: 08/23/2023] [Indexed: 09/19/2023] Open
Abstract
Q/R editing of the kainate receptor (KAR) subunit GluK2 radically alters recombinant KAR properties, but the effects on endogenous KARs in vivo remain largely unexplored. Here, we compared GluK2 editing-deficient mice that express ∼95% unedited GluK2(Q) to wild-type counterparts that express ∼85% edited GluK2(R). At mossy fiber-CA3 (MF-CA3) synapses GluK2(Q) mice displayed increased postsynaptic KAR function and KAR-mediated presynaptic facilitation, demonstrating enhanced ionotropic function. Conversely, GluK2(Q) mice exhibited reduced metabotropic KAR function, assessed by KAR-mediated inhibition of slow after-hyperpolarization currents (ISAHP). GluK2(Q) mice also had fewer GluA1-and GluA3-containing AMPA receptors (AMPARs) and reduced postsynaptic AMPAR currents at both MF-CA3 and CA1-Schaffer collateral synapses. Moreover, long-term potentiation of AMPAR-mediated transmission at CA1-Schaffer collateral synapses was reduced in GluK2(Q) mice. These findings suggest that GluK2 Q/R editing influences ionotropic/metabotropic balance of KAR signaling to regulate synaptic expression of AMPARs and plasticity.
Collapse
Affiliation(s)
- Jithin D. Nair
- Centre for Synaptic Plasticity, School of Biochemistry, Centre for Synaptic Plasticity, Biomedical Sciences Building, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - Kevin A. Wilkinson
- Centre for Synaptic Plasticity, School of Biochemistry, Centre for Synaptic Plasticity, Biomedical Sciences Building, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - Busra P. Yucel
- Centre for Synaptic Plasticity, School of Biochemistry, Centre for Synaptic Plasticity, Biomedical Sciences Building, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - Christophe Mulle
- CNRS UMR 5297, Interdisciplinary Institute of Neuroscience, University of Bordeaux, France
| | - Bryce Vissel
- Centre for Neuroscience and Regenerative Medicine, St Vincent’s Hospital, Sydney, NSW, Australia
| | - Jack Mellor
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - Jeremy M. Henley
- Centre for Synaptic Plasticity, School of Biochemistry, Centre for Synaptic Plasticity, Biomedical Sciences Building, University of Bristol, University Walk, Bristol BS8 1TD, UK
| |
Collapse
|
4
|
Palacios-Filardo J, Udakis M, Brown GA, Tehan BG, Congreve MS, Nathan PJ, Brown AJH, Mellor JR. Acetylcholine prioritises direct synaptic inputs from entorhinal cortex to CA1 by differential modulation of feedforward inhibitory circuits. Nat Commun 2021; 12:5475. [PMID: 34531380 PMCID: PMC8445995 DOI: 10.1038/s41467-021-25280-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Accepted: 07/21/2021] [Indexed: 02/08/2023] Open
Abstract
Acetylcholine release in the hippocampus plays a central role in the formation of new memory representations. An influential but largely untested theory proposes that memory formation requires acetylcholine to enhance responses in CA1 to new sensory information from entorhinal cortex whilst depressing inputs from previously encoded representations in CA3. Here, we show that excitatory inputs from entorhinal cortex and CA3 are depressed equally by synaptic release of acetylcholine in CA1. However, feedforward inhibition from entorhinal cortex exhibits greater depression than CA3 resulting in a selective enhancement of excitatory-inhibitory balance and CA1 activation by entorhinal inputs. Entorhinal and CA3 pathways engage different feedforward interneuron subpopulations and cholinergic modulation of presynaptic function is mediated differentially by muscarinic M3 and M4 receptors, respectively. Thus, our data support a role and mechanisms for acetylcholine to prioritise novel information inputs to CA1 during memory formation.
Collapse
Affiliation(s)
- Jon Palacios-Filardo
- Center for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience, University of Bristol, University Walk, Bristol, UK
| | - Matt Udakis
- Center for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience, University of Bristol, University Walk, Bristol, UK
| | - Giles A Brown
- Sosei Heptares, Steinmetz Building, Granta Park, Great Abingdon, Cambridge, UK
- OMass Therapeutics Ltd, The Schrödinger Building, Oxford, UK
| | - Benjamin G Tehan
- Sosei Heptares, Steinmetz Building, Granta Park, Great Abingdon, Cambridge, UK
- OMass Therapeutics Ltd, The Schrödinger Building, Oxford, UK
| | - Miles S Congreve
- Sosei Heptares, Steinmetz Building, Granta Park, Great Abingdon, Cambridge, UK
| | - Pradeep J Nathan
- Department of Psychiatry, University of Cambridge, Cambridge, UK
| | - Alastair J H Brown
- Sosei Heptares, Steinmetz Building, Granta Park, Great Abingdon, Cambridge, UK
| | - Jack R Mellor
- Center for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience, University of Bristol, University Walk, Bristol, UK.
| |
Collapse
|
5
|
Nair JD, Wilkinson KA, Henley JM, Mellor JR. Kainate receptors and synaptic plasticity. Neuropharmacology 2021; 196:108540. [PMID: 33794245 DOI: 10.1016/j.neuropharm.2021.108540] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 03/22/2021] [Accepted: 03/23/2021] [Indexed: 10/21/2022]
Abstract
Synaptic plasticity has classically been characterized to involve the NMDA and AMPA subtypes of glutamate receptors, with NMDA receptors providing the key trigger for the induction of long-term plasticity leading to changes in AMPA receptor expression. Here we review the more subtle roles played by kainate receptors, which contribute critical postsynaptic signalling as well as playing major presynaptic auto-receptor roles. We focus on two research areas: plasticity of kainate receptors themselves and the contribution they make to the plasticity of synaptic transmission. This article is part of the special issue on Glutamate Receptors - Kainate receptors.
Collapse
Affiliation(s)
- Jithin D Nair
- Center for Synaptic Plasticity, School of Biochemistry, University of Bristol, University Walk, Bristol, BS8 1TD, UK
| | - Kevin A Wilkinson
- Center for Synaptic Plasticity, School of Biochemistry, University of Bristol, University Walk, Bristol, BS8 1TD, UK
| | - Jeremy M Henley
- Center for Synaptic Plasticity, School of Biochemistry, University of Bristol, University Walk, Bristol, BS8 1TD, UK
| | - Jack R Mellor
- Center for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience, University of Bristol, University Walk, Bristol, BS8 1TD, UK.
| |
Collapse
|
6
|
Li W, Kutas M, Gray JA, Hagerman RH, Olichney JM. The Role of Glutamate in Language and Language Disorders - Evidence from ERP and Pharmacologic Studies. Neurosci Biobehav Rev 2020; 119:217-241. [PMID: 33039453 DOI: 10.1016/j.neubiorev.2020.09.023] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Revised: 08/10/2020] [Accepted: 09/21/2020] [Indexed: 12/31/2022]
Abstract
Current models of language processing do not address mechanisms at the neurotransmitter level, nor how pharmacologic agents may improve language function(s) in seemingly disparate disorders. L-Glutamate, the primary excitatory neurotransmitter in the human brain, is extensively involved in various higher cortical functions. We postulate that the physiologic role of L-Glutamate neurotransmission extends to the regulation of language access, comprehension, and production, and that disorders in glutamatergic transmission and circuitry contribute to the pathogenesis of neurodegenerative diseases and sporadic-onset language disorders such as the aphasic stroke syndromes. We start with a review of basic science data pertaining to various glutamate receptors in the CNS and ways that they may influence the physiological processes of language access and comprehension. We then focus on the dysregulation of glutamate neurotransmission in three conditions in which language dysfunction is prominent: Alzheimer's Disease, Fragile X-associated Tremor/Ataxia Syndrome, and Aphasic Stroke Syndromes. Finally, we review the pharmacologic and electrophysiologic (event related brain potential or ERP) data pertaining to the role glutamate neurotransmission plays in language processing and disorders.
Collapse
Affiliation(s)
- Wentao Li
- Department of Neurology, University of California, Davis, 4860 Y Street, Suite 3700, Sacramento, CA, 95817, USA.
| | - Marta Kutas
- Department of Cognitive Science, University of California, San Diego, 9500 Gilman Drive #0515, La Jolla, CA, 92093, USA; Department of Neurosciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA.
| | - John A Gray
- Department of Neurology, University of California, Davis, 4860 Y Street, Suite 3700, Sacramento, CA, 95817, USA; Center for Neuroscience, University of California, Davis, 1544 Newton Court, Davis, CA, 95618, USA.
| | - Randi H Hagerman
- MIND Institute, University of California, Davis, 2825 50th Street, Sacramento, CA, 95817, USA.
| | - John M Olichney
- Department of Neurology, University of California, Davis, 4860 Y Street, Suite 3700, Sacramento, CA, 95817, USA; Center for Mind and Brain, University of California, Davis, 267 Cousteau Place, Davis, CA, 95618, USA.
| |
Collapse
|
7
|
Jenner P, Mori A, Kanda T. Can adenosine A2A receptor antagonists be used to treat cognitive impairment, depression or excessive sleepiness in Parkinson's disease? Parkinsonism Relat Disord 2020; 80 Suppl 1:S28-S36. [DOI: 10.1016/j.parkreldis.2020.09.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Accepted: 09/15/2020] [Indexed: 01/29/2023]
|
8
|
Pressey JC, Woodin MA. Kainate receptor regulation of synaptic inhibition in the hippocampus. J Physiol 2020; 599:485-492. [PMID: 32162694 DOI: 10.1113/jp279645] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 03/02/2020] [Indexed: 12/13/2022] Open
Abstract
Kainate receptors (KARs) are glutamate-type receptors that mediate both canonical ionotropic currents and non-canonical metabotropic signalling. While KARs are expressed widely throughout the brain, synaptic KAR currents have only been recorded at a limited set of synapses, and the KAR currents that have been recorded are relatively small and slow, which has led to the question, what is the functional significance of KARs? While the KAR current itself is relatively modest, its impact on inhibition in the hippocampus can be profound. In the CA1 region of the hippocampus, presynaptic KAR activation bidirectionally regulates γ-aminobutyric acid (GABA) release in a manner that depends on the glutamate concentration; lower levels of glutamate facilitate GABA release via an ionotropic pathway, while higher levels of glutamate depress GABA release via a metabotropic pathway. Postsynaptic interneuron KAR activation increases spike frequency through an ionotropic current, which in turn can strengthen inhibition. In the CA3 region, postsynaptic KAR activation in pyramidal neurons also strengthens inhibition, but in this case through a metabotropic pathway which regulates the neuronal chloride gradient and hyperpolarizes the reversal potential for GABA (EGABA ). Taken together, the evidence for KAR-mediated regulation of the strength of inhibition via pre- and postsynaptic mechanisms provides compelling evidence that KARs are ideally positioned to regulate excitation-inhibition balance - through sensing the excitatory tone and concomitantly tuning the strength of inhibition.
Collapse
Affiliation(s)
- Jessica C Pressey
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Melanie A Woodin
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| |
Collapse
|
9
|
Mild hypothermia protects synaptic transmission from experimental ischemia through reduction in the function of nucleoside transporters in the mouse hippocampus. Neuropharmacology 2019; 163:107853. [PMID: 31734385 DOI: 10.1016/j.neuropharm.2019.107853] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Revised: 10/28/2019] [Accepted: 11/12/2019] [Indexed: 12/24/2022]
Abstract
Ischemia, a severe metabolic stress, increases adenosine levels and causes the suppression of synaptic transmission through adenosine A1 receptors. Although temperature also regulates extracellular adenosine levels, the effect of temperature on ischemia-induced activation of adenosine receptors is not yet fully understood. Here we examined the role of adenosine A1 receptors in mild hypothermia-mediated neuroprotection during the acute phase of ischemia. Severe ischemia-induced neurosynaptic impairment was reproduced by oxygen-glucose deprivation at normothermia (36 °C) and assessed with extracellular recordings or whole-cell patch clamp recordings in acute hippocampal slices in mice. Mild hypothermia (32 °C) induced the protection of synaptic transmission by activating adenosine A1 receptors. Stricter hypothermia (28 °C) caused additional neuroprotective effects by extending the onset time to anoxic depolarization; however, this effect was not associated with adenosine A1 receptors. The response of exogenous adenosine-induced inhibition of hippocampal synaptic transmission was increased by lowering the temperature to 32 °C or 28 °C. Hypothermia also reduced the function of dipryidamole-sensitive nucleoside transporters. These findings suggest that an increased response of adenosine A1 receptors, caused by a reduction in the function of nucleoside transporters, is one mechanism by which therapeutic hypothermia (usually used within the mild range) mediates neurosynaptic protection in the acute phase of stroke.
Collapse
|
10
|
Kawamura M, Ruskin DN, Masino SA. Adenosine A 1 receptor-mediated protection of mouse hippocampal synaptic transmission against oxygen and/or glucose deprivation: a comparative study. J Neurophysiol 2019; 122:721-728. [PMID: 31242045 DOI: 10.1152/jn.00813.2018] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Adenosine receptors are widely expressed in the brain, and adenosine is a key bioactive substance for neuroprotection. In this article, we clarify systematically the role of adenosine A1 receptors during a range of timescales and conditions when a significant amount of adenosine is released. Using acute hippocampal slices obtained from mice that were wild type or null mutant for the adenosine A1 receptor, we quantified and characterized the impact of varying durations of experimental ischemia, hypoxia, and hypoglycemia on synaptic transmission in the CA1 subregion. In normal tissue, these three stressors rapidly and markedly reduced synaptic transmission, and only treatment of sufficient duration led to incomplete recovery. In contrast, inactivation of adenosine A1 receptors delayed and/or lessened the reduction in synaptic transmission during all three stressors and reduced the magnitude of the recovery significantly. We reproduced the responses to hypoxia and hypoglycemia by applying an adenosine A1 receptor antagonist, validating the clear effects of genetic receptor inactivation on synaptic transmission. We found activation of adenosine A1 receptor inhibited hippocampal synaptic transmission during the acute phase of ischemia, hypoxia, or hypoglycemia and caused the recovery from synaptic impairment after these three stressors using genetic mutant. These studies quantify the neuroprotective role of the adenosine A1 receptor during a variety of metabolic stresses within the same recording system.NEW & NOTEWORTHY Deprivation of oxygen and/or glucose causes a rapid adenosine A1 receptor-mediated decrease in synaptic transmission in mouse hippocampus. We quantified adenosine A1 receptor-mediated inhibition during and synaptic recovery after ischemia, hypoxia, and hypoglycemia of varying durations using a genetic mutant and confirmed these findings using pharmacology. Overall, using the same recording conditions, we found the acute response and the neuroprotective ability of the adenosine A1 receptor depended on the type and duration of deprivation event.
Collapse
Affiliation(s)
- Masahito Kawamura
- Department of Pharmacology, Jikei University School of Medicine, Tokyo, Japan
| | - David N Ruskin
- Department of Psychology and Neuroscience Program, Trinity College, Hartford, Connecticut
| | - Susan A Masino
- Department of Psychology and Neuroscience Program, Trinity College, Hartford, Connecticut
| |
Collapse
|
11
|
Chandra N, Awasthi R, Ozdogan T, Johenning FW, Imbrosci B, Morris G, Schmitz D, Barkai E. A Cellular Mechanism Underlying Enhanced Capability for Complex Olfactory Discrimination Learning. eNeuro 2019; 6:ENEURO.0198-18.2019. [PMID: 30783614 PMCID: PMC6378325 DOI: 10.1523/eneuro.0198-18.2019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 12/26/2018] [Accepted: 01/06/2019] [Indexed: 11/21/2022] Open
Abstract
The biological mechanisms underlying complex forms of learning requiring the understanding of rules based on previous experience are not yet known. Previous studies have raised the intriguing possibility that improvement in complex learning tasks requires the long-term modulation of intrinsic neuronal excitability, induced by reducing the conductance of the slow calcium-dependent potassium current (sIAHP) simultaneously in most neurons in the relevant neuronal networks in several key brain areas. Such sIAHP reduction is expressed in attenuation of the postburst afterhyperpolarization (AHP) potential, and thus in enhanced repetitive action potential firing. Using complex olfactory discrimination (OD) learning as a model for complex learning, we show that brief activation of the GluK2 subtype glutamate receptor results in long-lasting enhancement of neuronal excitability in neurons from controls, but not from trained rats. Such an effect can be obtained by a brief tetanic synaptic stimulation or by direct application of kainate, both of which reduce the postburst AHP in pyramidal neurons. Induction of long-lasting enhancement of neuronal excitability is mediated via a metabotropic process that requires PKC and ERK activation. Intrinsic neuronal excitability cannot be modulated by synaptic activation in neurons from GluK2 knock-out mice. Accordingly, these mice are incapable of learning the complex OD task. Moreover, viral-induced overexpression of Gluk2 in piriform cortex pyramidal neurons results in remarkable enhancement of complex OD learning. Thus, signaling via kainate receptors has a central functional role in higher cognitive abilities.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | - Edi Barkai
- University of Haifa, Haifa 3498838, Israel
| |
Collapse
|
12
|
Marked bias towards spontaneous synaptic inhibition distinguishes non-adapting from adapting layer 5 pyramidal neurons in the barrel cortex. Sci Rep 2017; 7:14959. [PMID: 29097689 PMCID: PMC5668277 DOI: 10.1038/s41598-017-14971-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 10/19/2017] [Indexed: 11/18/2022] Open
Abstract
Pyramidal neuron subtypes differ in intrinsic electrophysiology properties and dendritic morphology. However, do different pyramidal neuron subtypes also receive synaptic inputs that are dissimilar in frequency and in excitation/inhibition balance? Unsupervised clustering of three intrinsic parameters that vary by cell subtype – the slow afterhyperpolarization, the sag, and the spike frequency adaptation – split layer 5 barrel cortex pyramidal neurons into two clusters: one of adapting cells and one of non-adapting cells, corresponding to previously described thin- and thick-tufted pyramidal neurons, respectively. Non-adapting neurons presented frequencies of spontaneous inhibitory postsynaptic currents (sIPSCs) and spontaneous excitatory postsynaptic currents (sEPSCs) three- and two-fold higher, respectively, than those of adapting neurons. The IPSC difference between pyramidal subtypes was activity independent. A subset of neurons were thy1-GFP positive, presented characteristics of non-adapting pyramidal neurons, and also had higher IPSC and EPSC frequencies than adapting neurons. The sEPSC/sIPSC frequency ratio was higher in adapting than in non-adapting cells, suggesting a higher excitatory drive in adapting neurons. Therefore, our study on spontaneous synaptic inputs suggests a different extent of synaptic information processing in adapting and non-adapting barrel cortex neurons, and that eventual deficits in inhibition may have differential effects on the excitation/inhibition balance in adapting and non-adapting neurons.
Collapse
|
13
|
Rebola N, Carta M, Mulle C. Operation and plasticity of hippocampal CA3 circuits: implications for memory encoding. Nat Rev Neurosci 2017; 18:208-220. [DOI: 10.1038/nrn.2017.10] [Citation(s) in RCA: 96] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
|
14
|
Cunha RA. How does adenosine control neuronal dysfunction and neurodegeneration? J Neurochem 2016; 139:1019-1055. [PMID: 27365148 DOI: 10.1111/jnc.13724] [Citation(s) in RCA: 312] [Impact Index Per Article: 39.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Revised: 05/23/2016] [Accepted: 06/23/2016] [Indexed: 12/11/2022]
Abstract
The adenosine modulation system mostly operates through inhibitory A1 (A1 R) and facilitatory A2A receptors (A2A R) in the brain. The activity-dependent release of adenosine acts as a brake of excitatory transmission through A1 R, which are enriched in glutamatergic terminals. Adenosine sharpens salience of information encoding in neuronal circuits: high-frequency stimulation triggers ATP release in the 'activated' synapse, which is locally converted by ecto-nucleotidases into adenosine to selectively activate A2A R; A2A R switch off A1 R and CB1 receptors, bolster glutamate release and NMDA receptors to assist increasing synaptic plasticity in the 'activated' synapse; the parallel engagement of the astrocytic syncytium releases adenosine further inhibiting neighboring synapses, thus sharpening the encoded plastic change. Brain insults trigger a large outflow of adenosine and ATP, as a danger signal. A1 R are a hurdle for damage initiation, but they desensitize upon prolonged activation. However, if the insult is near-threshold and/or of short-duration, A1 R trigger preconditioning, which may limit the spread of damage. Brain insults also up-regulate A2A R, probably to bolster adaptive changes, but this heightens brain damage since A2A R blockade affords neuroprotection in models of epilepsy, depression, Alzheimer's, or Parkinson's disease. This initially involves a control of synaptotoxicity by neuronal A2A R, whereas astrocytic and microglia A2A R might control the spread of damage. The A2A R signaling mechanisms are largely unknown since A2A R are pleiotropic, coupling to different G proteins and non-canonical pathways to control the viability of glutamatergic synapses, neuroinflammation, mitochondria function, and cytoskeleton dynamics. Thus, simultaneously bolstering A1 R preconditioning and preventing excessive A2A R function might afford maximal neuroprotection. The main physiological role of the adenosine modulation system is to sharp the salience of information encoding through a combined action of adenosine A2A receptors (A2A R) in the synapse undergoing an alteration of synaptic efficiency with an increased inhibitory action of A1 R in all surrounding synapses. Brain insults trigger an up-regulation of A2A R in an attempt to bolster adaptive plasticity together with adenosine release and A1 R desensitization; this favors synaptotocity (increased A2A R) and decreases the hurdle to undergo degeneration (decreased A1 R). Maximal neuroprotection is expected to result from a combined A2A R blockade and increased A1 R activation. This article is part of a mini review series: "Synaptic Function and Dysfunction in Brain Diseases".
Collapse
Affiliation(s)
- Rodrigo A Cunha
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,FMUC-Faculty of Medicine, University of Coimbra, Coimbra, Portugal
| |
Collapse
|
15
|
Activity-dependent upregulation of presynaptic kainate receptors at immature CA3-CA1 synapses. J Neurosci 2015; 34:16902-16. [PMID: 25505341 DOI: 10.1523/jneurosci.1842-14.2014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Presynaptic kainate-type glutamate receptors (KARs) regulate glutamate release probability and short-term plasticity in various areas of the brain. Here we show that long-term depression (LTD) in the area CA1 of neonatal rodent hippocampus is associated with an upregulation of tonic inhibitory KAR activity, which contributes to synaptic depression and causes a pronounced increase in short-term facilitation of transmission. This increased KAR function was mediated by high-affinity receptors and required activation of NMDA receptors, nitric oxide (NO) synthetase, and postsynaptic calcium signaling. In contrast, KAR activity was irreversibly downregulated in response to induction of long-term potentiation in a manner that depended on activation of the TrkB-receptor of BDNF. Both tonic KAR activity and its plasticity were restricted to early stages of synapse development and were lost in parallel with maturation of the network due to ongoing BDNF-TrkB signaling. These data show that presynaptic KARs are targets for activity-dependent modulation via diffusible messengers NO and BDNF, which enhance and depress tonic KAR activity at immature synapses, respectively. The plasticity of presynaptic KARs in the developing network allows nascent synapses to shape their response to incoming activity. In particular, upregulation of KAR function after LTD allows the synapse to preferentially pass high-frequency afferent activity. This can provide a potential rescue from synapse elimination by uncorrelated activity and also increase the computational dynamics of the developing CA3-CA1 circuitry.
Collapse
|
16
|
Rombo DM, Newton K, Nissen W, Badurek S, Horn JM, Minichiello L, Jefferys JG, Sebastiao AM, Lamsa KP. Synaptic mechanisms of adenosine A
2A
receptor‐mediated hyperexcitability in the hippocampus. Hippocampus 2014; 25:566-80. [DOI: 10.1002/hipo.22392] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/12/2014] [Indexed: 02/06/2023]
Affiliation(s)
- Diogo M. Rombo
- Institute of Pharmacology and Neurosciences, Faculty of Medicine, University of Lisbon Portugal
- Unit of Neurosciences, Institute of Molecular Medicine, University of Lisbon Portugal
- Department of PharmacologyOxford UniversityOxford United Kingdom
| | - Kathryn Newton
- Medical Research Council Anatomical Neuropharmacology Unit at the Department of Pharmacology, Oxford UniversityOxford United Kingdom
| | - Wiebke Nissen
- Department of PharmacologyOxford UniversityOxford United Kingdom
| | - Sylvia Badurek
- Centre for NeuroregenerationUniversity of EdinburghEdinburgh United Kingdom
| | - Jacqueline M. Horn
- Department of PharmacologyOxford UniversityOxford United Kingdom
- Centre for NeuroregenerationUniversity of EdinburghEdinburgh United Kingdom
| | - Liliana Minichiello
- Department of PharmacologyOxford UniversityOxford United Kingdom
- Centre for NeuroregenerationUniversity of EdinburghEdinburgh United Kingdom
| | - John G.R. Jefferys
- Department of PharmacologyOxford UniversityOxford United Kingdom
- School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of BirminghamBirmingham United Kingdom
| | - Ana M. Sebastiao
- Institute of Pharmacology and Neurosciences, Faculty of Medicine, University of Lisbon Portugal
- Unit of Neurosciences, Institute of Molecular Medicine, University of Lisbon Portugal
| | - Karri P. Lamsa
- Department of PharmacologyOxford UniversityOxford United Kingdom
- Medical Research Council Anatomical Neuropharmacology Unit at the Department of Pharmacology, Oxford UniversityOxford United Kingdom
| |
Collapse
|
17
|
Carta M, Fièvre S, Gorlewicz A, Mulle C. Kainate receptors in the hippocampus. Eur J Neurosci 2014; 39:1835-44. [PMID: 24738709 DOI: 10.1111/ejn.12590] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Revised: 03/12/2014] [Accepted: 03/14/2014] [Indexed: 01/23/2023]
Abstract
Kainate receptors (KARs) consist of a family of ionotropic glutamate receptors composed of the combinations of five subunits, GluK1-GluK5. Although KARs display close structural homology with AMPA receptors, they serve quite distinct functions. A great deal of our knowledge of the molecular and functional properties of KARs comes from their study in the hippocampus. This review aims at summarising the functions of KARs in the regulation of the activity of hippocampal synaptic circuits at the adult stage and throughout development. We focus on the variety of roles played by KARs in physiological conditions of activation, at pre- and postsynaptic sites, in different cell types and through either metabotropic or ionotropic actions. Finally, we present some of the few attempts to link the role of KARs in the regulation of local hippocampal circuits to the behavioural functions of the hippocampus in health and diseases.
Collapse
Affiliation(s)
- Mario Carta
- Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, University of Bordeaux, F-33000, Bordeaux, France
| | | | | | | |
Collapse
|
18
|
Abstract
Our understanding of the molecular properties of kainate receptors and their involvement in synaptic physiology has progressed significantly over the last 30 years. A plethora of studies indicate that kainate receptors are important mediators of the pre- and postsynaptic actions of glutamate, although the mechanisms underlying such effects are still often a topic for discussion. Three clear fields related to their behavior have emerged: there are a number of interacting proteins that pace the properties of kainate receptors; their activity is unconventional since they can also signal through G proteins, behaving like metabotropic receptors; they seem to be linked to some devastating brain diseases. Despite the significant progress in their importance in brain function, kainate receptors remain somewhat puzzling. Here we examine discoveries linking these receptors to physiology and their probable implications in disease, in particular mood disorders, and propose some ideas to obtain a deeper understanding of these intriguing proteins.
Collapse
|
19
|
Chen JF. Adenosine receptor control of cognition in normal and disease. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2014; 119:257-307. [PMID: 25175970 DOI: 10.1016/b978-0-12-801022-8.00012-x] [Citation(s) in RCA: 100] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Adenosine and adenosine receptors (ARs) are increasingly recognized as important therapeutic targets for controlling cognition under normal and disease conditions for its dual roles of neuromodulation as well as of homeostatic function in the brain. This chapter first presents the unique ability of adenosine, by acting on the inhibitory A1 and facilitating A2A receptor, to integrate dopamine, glutamate, and BNDF signaling and to modulate synaptic plasticity (e.g., long-term potentiation and long-term depression) in brain regions relevant to learning and memory, providing the molecular and cellular bases for adenosine receptor (AR) control of cognition. This led to the demonstration of AR modulation of social recognition memory, working memory, reference memory, reversal learning, goal-directed behavior/habit formation, Pavlovian fear conditioning, and effort-related behavior. Furthermore, human and animal studies support that AR activity can also, through cognitive enhancement and neuroprotection, reverse cognitive impairments in animal models of Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease, and schizophrenia. Lastly, epidemiological evidence indicates that regular human consumption of caffeine, the most widely used psychoactive drug and nonselective AR antagonists, is associated with the reduced cognitive decline in aging and AD patients, and with the reduced risk in developing PD. Thus, there is a convergence of the molecular studies revealing AR as molecular targets for integrating neurotransmitter signaling and controlling synaptic plasticity, with animal studies demonstrating the strong procognitive impact upon AR antagonism in normal and disease brains and with epidemiological and clinical evidences in support of caffeine and AR drugs for therapeutic modulation of cognition. Since some of adenosine A2A receptor antagonists are already in phase III clinical trials for motor benefits in PD patients with remarkable safety profiles, additional animal and human studies to better understand the mechanism underlying the AR-mediated control of cognition under normal and disease conditions will provide the required rationale to stimulate the necessary clinical investigation to rapidly translate adenosine and AR drug as a novel strategy to control memory impairment in neuropsychiatric disorders.
Collapse
Affiliation(s)
- Jiang-Fan Chen
- Department of Neurology, Boston University School of Medicine, Boston, Massachusetts, USA; The Molecular Medicine Institute, Wenzhou Medical University, Wenzhou, Zhejiang, PR China.
| |
Collapse
|