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Orser BA. Discovering the Intriguing Properties of Extrasynaptic γ-Aminobutyric Acid Type A Receptors. Anesthesiology 2024; 140:1192-1200. [PMID: 38624275 DOI: 10.1097/aln.0000000000004949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/17/2024]
Abstract
Tonic inhibition in mouse hippocampal CA1 pyramidal neurons is mediated by α5 subunit-containing γ-aminobutyric acid type A receptors. By Caraiscos VB, Elliott EM, You-Ten KE, Cheng VY, Belelli D, Newell JG, Jackson MF, Lambert JJ, Rosahl TW, Wafford KA, MacDonald JF, Orser BA. Proc Natl Acad Sci U S A 2004; 101:3662-7. Reprinted with permission. In this Classic Paper Revisited, the author recounts the scientific journey leading to a report published in the Proceedings of the National Academy of Sciences (PNAS) and shares several personal stories from her formative years and "research truths" that she has learned along the way. Briefly, the principal inhibitory neurotransmitter in the brain, γ-aminobutyric acid (GABA), was conventionally thought to regulate cognitive processes by activating synaptic GABA type A (GABAA) receptors and generating transient inhibitory synaptic currents. However, the author's laboratory team discovered a novel nonsynaptic form of tonic inhibition in hippocampal pyramidal neurons, mediated by extrasynaptic GABAA receptors that are pharmacologically distinct from synaptic GABAA receptors. This tonic current is highly sensitive to most general anesthetics, including sevoflurane and propofol, and likely contributes to the memory-blocking properties of these drugs. Before the publication in PNAS, the subunit composition of GABAA receptors that generate the tonic current was unknown. The team's research showed that GABAA receptors containing the α5 subunit (α5GABAARs) generated the tonic inhibitory current in hippocampal neurons. α5GABAARs are highly sensitive to GABA, desensitize slowly, and are thus well suited for detecting low, persistent, ambient concentrations of GABA in the extracellular space. Interest in α5GABAARs has surged since the PNAS report, driven by their pivotal roles in cognitive processes and their potential as therapeutic targets for treating various neurologic disorders.
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Affiliation(s)
- Beverley A Orser
- Department of Anesthesiology and Pain Medicine, and Department of Physiology, University of Toronto, Toronto, Canada
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2
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Fleming EA, Field GD, Tadross MR, Hull C. Local synaptic inhibition mediates cerebellar granule cell pattern separation and enables learned sensorimotor associations. Nat Neurosci 2024; 27:689-701. [PMID: 38321293 DOI: 10.1038/s41593-023-01565-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Accepted: 12/21/2023] [Indexed: 02/08/2024]
Abstract
The cerebellar cortex has a key role in generating predictive sensorimotor associations. To do so, the granule cell layer is thought to establish unique sensorimotor representations for learning. However, how this is achieved and how granule cell population responses contribute to behavior have remained unclear. To address these questions, we have used in vivo calcium imaging and granule cell-specific pharmacological manipulation of synaptic inhibition in awake, behaving mice. These experiments indicate that inhibition sparsens and thresholds sensory responses, limiting overlap between sensory ensembles and preventing spiking in many granule cells that receive excitatory input. Moreover, inhibition can be recruited in a stimulus-specific manner to powerfully decorrelate multisensory ensembles. Consistent with these results, granule cell inhibition is required for accurate cerebellum-dependent sensorimotor behavior. These data thus reveal key mechanisms for granule cell layer pattern separation beyond those envisioned by classical models.
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Affiliation(s)
| | - Greg D Field
- Department of Neurobiology, Duke University Medical School, Durham, NC, USA
- Stein Eye Institute, Department of Ophthalmology, University of California, Los Angeles, CA, USA
| | - Michael R Tadross
- Department of Neurobiology, Duke University Medical School, Durham, NC, USA
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Court Hull
- Department of Neurobiology, Duke University Medical School, Durham, NC, USA.
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3
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Untiet V. Astrocytic chloride regulates brain function in health and disease. Cell Calcium 2024; 118:102855. [PMID: 38364706 DOI: 10.1016/j.ceca.2024.102855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 02/02/2024] [Accepted: 02/06/2024] [Indexed: 02/18/2024]
Abstract
Chloride ions (Cl-) play a pivotal role in synaptic inhibition in the central nervous system, primarily mediated through ionotropic mechanisms. A recent breakthrough emphathizes the significant influence of astrocytic intracellular chloride concentration ([Cl-]i) regulation, a field still in its early stages of exploration. Typically, the [Cl-]i in most animal cells is maintained at lower levels than the extracellular chloride [Cl-]o, a critical balance to prevent cell swelling due to osmotic pressure. Various Cl- transporters are expressed differently across cell types, fine-tuning the [Cl-]i, while Cl- gradients are utilised by several families of Cl- channels. Although the passive distribution of ions within cells is governed by basic biophysical principles, astrocytes actively expend energy to sustain [Cl-]i at much higher levels than those achieved passively, and much higher than neuronal [Cl-]i. Beyond the role in volume regulation, astrocytic [Cl-]i is dynamically linked to brain states and influences neuronal signalling in actively behaving animals. As a vital component of brain function, astrocytic [Cl-]i also plays a role in the development of disorders where inhibitory transmission is disrupted. This review synthesises the latest insights into astrocytic [Cl-]i, elucidating its role in modulating brain function and its implications in various pathophysiological conditions.
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Affiliation(s)
- Verena Untiet
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, University of Copenhagen, 2200 Copenhagen, Denmark.
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4
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Castagno AN, Spaiardi P, Trucco A, Maniezzi C, Raffin F, Mancini M, Nicois A, Cazzola J, Pedrinazzi M, Del Papa P, Pisani A, Talpo F, Biella GR. Oxytocin Modifies the Excitability and the Action Potential Shape of the Hippocampal CA1 GABAergic Interneurons. Int J Mol Sci 2024; 25:2613. [PMID: 38473860 DOI: 10.3390/ijms25052613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2023] [Revised: 02/19/2024] [Accepted: 02/20/2024] [Indexed: 03/14/2024] Open
Abstract
Oxytocin (OT) is a neuropeptide that modulates social-related behavior and cognition in the central nervous system of mammals. In the CA1 area of the hippocampus, the indirect effects of the OT on the pyramidal neurons and their role in information processing have been elucidated. However, limited data are available concerning the direct modulation exerted by OT on the CA1 interneurons (INs) expressing the oxytocin receptor (OTR). Here, we demonstrated that TGOT (Thr4,Gly7-oxytocin), a selective OTR agonist, affects not only the membrane potential and the firing frequency but also the neuronal excitability and the shape of the action potentials (APs) of these INs in mice. Furthermore, we constructed linear mixed-effects models (LMMs) to unravel the dependencies between the AP parameters and the firing frequency, also considering how TGOT can interact with them to strengthen or weaken these influences. Our analyses indicate that OT regulates the functionality of the CA1 GABAergic INs through different and independent mechanisms. Specifically, the increase in neuronal firing rate can be attributed to the depolarizing effect on the membrane potential and the related enhancement in cellular excitability by the peptide. In contrast, the significant changes in the AP shape are directly linked to oxytocinergic modulation. Importantly, these alterations in AP shape are not associated with the TGOT-induced increase in neuronal firing rate, being themselves critical for signal processing.
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Affiliation(s)
- Antonio Nicolas Castagno
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, 27100 Pavia, Italy
- Department of Brain and Behavioral Sciences, University of Pavia, 27100 Pavia, Italy
- IRCCS Mondino Foundation, 27100 Pavia, Italy
| | - Paolo Spaiardi
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, 27100 Pavia, Italy
- INFN-Pavia Section, 27100 Pavia, Italy
| | - Arianna Trucco
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, 27100 Pavia, Italy
| | - Claudia Maniezzi
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, 20126 Milano, Italy
| | - Francesca Raffin
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, 27100 Pavia, Italy
| | - Maria Mancini
- Department of Brain and Behavioral Sciences, University of Pavia, 27100 Pavia, Italy
| | - Alessandro Nicois
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, 27100 Pavia, Italy
- Institute of Biomolecular Chemistry, Consiglio Nazionale delle Ricerche (CNR), 80078 Pozzuoli, Italy
- Department of Biomolecular Sciences, University of Urbino Carlo Bo, 61029 Urbino, Italy
| | - Jessica Cazzola
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, 27100 Pavia, Italy
| | - Matilda Pedrinazzi
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, 27100 Pavia, Italy
| | - Paola Del Papa
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, 27100 Pavia, Italy
| | - Antonio Pisani
- Department of Brain and Behavioral Sciences, University of Pavia, 27100 Pavia, Italy
- IRCCS Mondino Foundation, 27100 Pavia, Italy
| | - Francesca Talpo
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, 27100 Pavia, Italy
| | - Gerardo Rosario Biella
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, 27100 Pavia, Italy
- INFN-Pavia Section, 27100 Pavia, Italy
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5
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Oberle HM, Ford AN, Czarny JE, Rogalla MM, Apostolides PF. Recurrent Circuits Amplify Corticofugal Signals and Drive Feedforward Inhibition in the Inferior Colliculus. J Neurosci 2023; 43:5642-5655. [PMID: 37308295 PMCID: PMC10401644 DOI: 10.1523/jneurosci.0626-23.2023] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 06/02/2023] [Accepted: 06/06/2023] [Indexed: 06/14/2023] Open
Abstract
The inferior colliculus (IC) is a midbrain hub critical for perceiving complex sounds, such as speech. In addition to processing ascending inputs from most auditory brainstem nuclei, the IC receives descending inputs from auditory cortex that control IC neuron feature selectivity, plasticity, and certain forms of perceptual learning. Although corticofugal synapses primarily release the excitatory transmitter glutamate, many physiology studies show that auditory cortical activity has a net inhibitory effect on IC neuron spiking. Perplexingly, anatomy studies imply that corticofugal axons primarily target glutamatergic IC neurons while only sparsely innervating IC GABA neurons. Corticofugal inhibition of the IC may thus occur largely independently of feedforward activation of local GABA neurons. We shed light on this paradox using in vitro electrophysiology in acute IC slices from fluorescent reporter mice of either sex. Using optogenetic stimulation of corticofugal axons, we find that excitation evoked with single light flashes is indeed stronger in presumptive glutamatergic neurons compared with GABAergic neurons. However, many IC GABA neurons fire tonically at rest, such that sparse and weak excitation suffices to significantly increase their spike rates. Furthermore, a subset of glutamatergic IC neurons fire spikes during repetitive corticofugal activity, leading to polysynaptic excitation in IC GABA neurons owing to a dense intracollicular connectivity. Consequently, recurrent excitation amplifies corticofugal activity, drives spikes in IC GABA neurons, and generates substantial local inhibition in the IC. Thus, descending signals engage intracollicular inhibitory circuits despite apparent constraints of monosynaptic connectivity between auditory cortex and IC GABA neurons.SIGNIFICANCE STATEMENT Descending "corticofugal" projections are ubiquitous across mammalian sensory systems, and enable the neocortex to control subcortical activity in a predictive or feedback manner. Although corticofugal neurons are glutamatergic, neocortical activity often inhibits subcortical neuron spiking. How does an excitatory pathway generate inhibition? Here we study the corticofugal pathway from auditory cortex to inferior colliculus (IC), a midbrain hub important for complex sound perception. Surprisingly, cortico-collicular transmission was stronger onto IC glutamatergic compared with GABAergic neurons. However, corticofugal activity triggered spikes in IC glutamate neurons with local axons, thereby generating strong polysynaptic excitation and feedforward spiking of GABAergic neurons. Our results thus reveal a novel mechanism that recruits local inhibition despite limited monosynaptic convergence onto inhibitory networks.
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Affiliation(s)
- Hannah M Oberle
- Neuroscience Graduate Program
- Department of Otolaryngology, Head & Neck Surgery, Kresge Hearing Research Institute
| | - Alexander N Ford
- Department of Otolaryngology, Head & Neck Surgery, Kresge Hearing Research Institute
| | - Jordyn E Czarny
- Department of Otolaryngology, Head & Neck Surgery, Kresge Hearing Research Institute
| | - Meike M Rogalla
- Department of Otolaryngology, Head & Neck Surgery, Kresge Hearing Research Institute
| | - Pierre F Apostolides
- Department of Otolaryngology, Head & Neck Surgery, Kresge Hearing Research Institute
- Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48109
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Mätlik K, Govek EE, Paul MR, Allis CD, Hatten ME. Histone bivalency regulates the timing of cerebellar granule cell development. Genes Dev 2023; 37:570-589. [PMID: 37491148 PMCID: PMC10499015 DOI: 10.1101/gad.350594.123] [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: 03/02/2023] [Accepted: 07/10/2023] [Indexed: 07/27/2023]
Abstract
Developing neurons undergo a progression of morphological and gene expression changes as they transition from neuronal progenitors to mature neurons. Here we used RNA-seq and H3K4me3 and H3K27me3 ChIP-seq to analyze how chromatin modifications control gene expression in a specific type of CNS neuron: the mouse cerebellar granule cell (GC). We found that in proliferating GC progenitors (GCPs), H3K4me3/H3K27me3 bivalency is common at neuronal genes and undergoes dynamic changes that correlate with gene expression during migration and circuit formation. Expressing a fluorescent sensor for bivalent domains revealed subnuclear bivalent foci in proliferating GCPs. Inhibiting H3K27 methyltransferases EZH1 and EZH2 in vitro and in organotypic cerebellar slices dramatically altered the expression of bivalent genes, induced the down-regulation of migration-related genes and up-regulation of synaptic genes, inhibited glial-guided migration, and accelerated terminal differentiation. Thus, histone bivalency is required to regulate the timing of the progression from progenitor cells to mature neurons.
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Affiliation(s)
- Kärt Mätlik
- Laboratory of Developmental Neurobiology, Rockefeller University, New York, New York 10065, USA
| | - Eve-Ellen Govek
- Laboratory of Developmental Neurobiology, Rockefeller University, New York, New York 10065, USA
| | - Matthew R Paul
- Bioinformatics Resource Center, Rockefeller University, New York, New York 10065, USA
| | - C David Allis
- Laboratory of Chromatin Biology and Epigenetics, Rockefeller University, New York, New York 10065, USA
| | - Mary E Hatten
- Laboratory of Developmental Neurobiology, Rockefeller University, New York, New York 10065, USA;
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7
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Wyroślak M, Dobrzański G, Mozrzymas JW. Bidirectional plasticity of GABAergic tonic inhibition in hippocampal somatostatin- and parvalbumin-containing interneurons. Front Cell Neurosci 2023; 17:1193383. [PMID: 37448697 PMCID: PMC10336215 DOI: 10.3389/fncel.2023.1193383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Accepted: 06/05/2023] [Indexed: 07/15/2023] Open
Abstract
GABAA receptors present in extrasynaptic areas mediate tonic inhibition in hippocampal neurons regulating the performance of neural networks. In this study, we investigated the effect of NMDA-induced plasticity on tonic inhibition in somatostatin- and parvalbumin-containing interneurons. Using pharmacological methods and transgenic mice (SST-Cre/PV-Cre x Ai14), we induced the plasticity of GABAergic transmission in somatostatin- and parvalbumin-containing interneurons by a brief (3 min) application of NMDA. In the whole-cell patch-clamp configuration, we measured tonic currents enhanced by specific agonists (etomidate or gaboxadol). Furthermore, in both the control and NMDA-treated groups, we examined to what extent these changes depend on the regulation of distinct subtypes of GABAA receptors. Tonic conductance in the somatostatin-containing (SST+) interneurons is enhanced after NMDA application, and the observed effect is associated with an increased content of α5-containing GABAARs. Both fast-spiking and non-fast-spiking parvalbumin-positive (PV+) cells showed a reduction of tonic inhibition after plasticity induction. This effect was accompanied in both PV+ interneuron types by a strongly reduced proportion of δ-subunit-containing GABAARs and a relatively small increase in currents mediated by α5-containing GABAARs. Both somatostatin- and parvalbumin-containing interneurons show cell type-dependent and opposite sign plasticity of tonic inhibition. The underlying mechanisms depend on the cell-specific balance of plastic changes in the contents of α5 and δ subunit-containing GABAARs.
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Affiliation(s)
- Marcin Wyroślak
- Department of Biophysics and Neuroscience, Wroclaw Medical University, Wrocław, Poland
| | | | - Jerzy W. Mozrzymas
- Department of Biophysics and Neuroscience, Wroclaw Medical University, Wrocław, Poland
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8
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Fogarty MJ. Inhibitory Synaptic Influences on Developmental Motor Disorders. Int J Mol Sci 2023; 24:ijms24086962. [PMID: 37108127 PMCID: PMC10138861 DOI: 10.3390/ijms24086962] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 04/05/2023] [Accepted: 04/06/2023] [Indexed: 04/29/2023] Open
Abstract
During development, GABA and glycine play major trophic and synaptic roles in the establishment of the neuromotor system. In this review, we summarise the formation, function and maturation of GABAergic and glycinergic synapses within neuromotor circuits during development. We take special care to discuss the differences in limb and respiratory neuromotor control. We then investigate the influences that GABAergic and glycinergic neurotransmission has on two major developmental neuromotor disorders: Rett syndrome and spastic cerebral palsy. We present these two syndromes in order to contrast the approaches to disease mechanism and therapy. While both conditions have motor dysfunctions at their core, one condition Rett syndrome, despite having myriad symptoms, has scientists focused on the breathing abnormalities and their alleviation-to great clinical advances. By contrast, cerebral palsy remains a scientific quagmire or poor definitions, no widely adopted model and a lack of therapeutic focus. We conclude that the sheer abundance of diversity of inhibitory neurotransmitter targets should provide hope for intractable conditions, particularly those that exhibit broad spectra of dysfunction-such as spastic cerebral palsy and Rett syndrome.
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Affiliation(s)
- Matthew J Fogarty
- Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, MN 55902, USA
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9
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Naylor DE. In the fast lane: Receptor trafficking during status epilepticus. Epilepsia Open 2023; 8 Suppl 1:S35-S65. [PMID: 36861477 PMCID: PMC10173858 DOI: 10.1002/epi4.12718] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Accepted: 02/23/2023] [Indexed: 03/03/2023] Open
Abstract
Status epilepticus (SE) remains a significant cause of morbidity and mortality and often is refractory to standard first-line treatments. A rapid loss of synaptic inhibition and development of pharmacoresistance to benzodiazepines (BZDs) occurs early during SE, while NMDA and AMPA receptor antagonists remain effective treatments after BZDs have failed. Multimodal and subunit-selective receptor trafficking within minutes to an hour of SE involves GABA-A, NMDA, and AMPA receptors and contributes to shifts in the number and subunit composition of surface receptors with differential impacts on the physiology, pharmacology, and strength of GABAergic and glutamatergic currents at synaptic and extrasynaptic sites. During the first hour of SE, synaptic GABA-A receptors containing γ2 subunits move to the cell interior while extrasynaptic GABA-A receptors with δ subunits are preserved. Conversely, NMDA receptors containing N2B subunits are increased at synaptic and extrasynaptic sites, and homomeric GluA1 ("GluA2-lacking") calcium permeant AMPA receptor surface expression also is increased. Molecular mechanisms, largely driven by NMDA receptor or calcium permeant AMPA receptor activation early during circuit hyperactivity, regulate subunit-specific interactions with proteins involved with synaptic scaffolding, adaptin-AP2/clathrin-dependent endocytosis, endoplasmic reticulum (ER) retention, and endosomal recycling. Reviewed here is how SE-induced shifts in receptor subunit composition and surface representation increase the excitatory to inhibitory imbalance that sustains seizures and fuels excitotoxicity contributing to chronic sequela such as "spontaneous recurrent seizures" (SRS). A role for early multimodal therapy is suggested both for treatment of SE and for prevention of long-term comorbidities.
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Affiliation(s)
- David E Naylor
- VA Greater Los Angeles Healthcare System, Department of Neurology, David Geffen School of Medicine at UCLA, and The Lundquist Institute at Harbor-UCLA Medical Center, Los Angeles, California, USA
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10
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Mätlik K, Govek EE, Paul MR, Allis CD, Hatten ME. Histone bivalency regulates the timing of cerebellar granule cell development. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.02.526881. [PMID: 36778390 PMCID: PMC9915618 DOI: 10.1101/2023.02.02.526881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Developing neurons undergo a progression of morphological and gene expression changes as they transition from neuronal progenitors to mature, multipolar neurons. Here we use RNA-seq and H3K4me3 and H3K27me3 ChIP-seq to analyze how chromatin modifications control gene expression in a specific type of CNS neuron, the mouse cerebellar granule cell (GC). We find that in proliferating GC progenitors (GCPs), H3K4me3/H3K27me3 bivalency is common at neuronal genes and undergoes dynamic changes that correlate with gene expression during migration and circuit formation. Expressing a fluorescent sensor for bivalent H3K4me3 and H3K27me3 domains revealed subnuclear bivalent foci in proliferating GCPs. Inhibiting H3K27 methyltransferases EZH1 and EZH2 in vitro and in organotypic cerebellar slices dramatically altered the expression of bivalent genes and induced the downregulation of migration-related genes and upregulation of synaptic genes, inhibited glial-guided migration, and accelerated terminal differentiation. Thus, histone bivalency is required to regulate the timing of the progression from progenitor cells to mature neurons.
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Affiliation(s)
- Kärt Mätlik
- Laboratory of Developmental Neurobiology, Rockefeller University, 10065, New York, NY, USA
| | - Eve-Ellen Govek
- Laboratory of Developmental Neurobiology, Rockefeller University, 10065, New York, NY, USA
| | - Matthew R. Paul
- Bioinformatics Resource Center, Rockefeller University, 10065, New York, NY, USA
| | - C. David Allis
- Laboratory of Chromatin Biology and Epigenetics, Rockefeller University, 10065, New York, NY, USA
| | - Mary E. Hatten
- Laboratory of Developmental Neurobiology, Rockefeller University, 10065, New York, NY, USA
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11
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The GABA and GABA-Receptor System in Inflammation, Anti-Tumor Immune Responses, and COVID-19. Biomedicines 2023; 11:biomedicines11020254. [PMID: 36830790 PMCID: PMC9953446 DOI: 10.3390/biomedicines11020254] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 01/16/2023] [Accepted: 01/16/2023] [Indexed: 01/20/2023] Open
Abstract
GABA and GABAA-receptors (GABAA-Rs) play major roles in neurodevelopment and neurotransmission in the central nervous system (CNS). There has been a growing appreciation that GABAA-Rs are also present on most immune cells. Studies in the fields of autoimmune disease, cancer, parasitology, and virology have observed that GABA-R ligands have anti-inflammatory actions on T cells and antigen-presenting cells (APCs), while also enhancing regulatory T cell (Treg) responses and shifting APCs toward anti-inflammatory phenotypes. These actions have enabled GABAA-R ligands to ameliorate autoimmune diseases, such as type 1 diabetes (T1D), multiple sclerosis (MS), and rheumatoid arthritis, as well as type 2 diabetes (T2D)-associated inflammation in preclinical models. Conversely, antagonism of GABAA-R activity promotes the pro-inflammatory responses of T cells and APCs, enhancing anti-tumor responses and reducing tumor burden in models of solid tumors. Lung epithelial cells also express GABA-Rs, whose activation helps maintain fluid homeostasis and promote recovery from injury. The ability of GABAA-R agonists to limit both excessive immune responses and lung epithelial cell injury may underlie recent findings that GABAA-R agonists reduce the severity of disease in mice infected with highly lethal coronaviruses (SARS-CoV-2 and MHV-1). These observations suggest that GABAA-R agonists may provide off-the-shelf therapies for COVID-19 caused by new SARS-CoV-2 variants, as well as novel beta-coronaviruses, which evade vaccine-induced immune responses and antiviral medications. We review these findings and further advance the notions that (1) immune cells possess GABAA-Rs to limit inflammation in the CNS, and (2) this natural "braking system" on inflammatory responses may be pharmacologically engaged to slow the progression of autoimmune diseases, reduce the severity of COVID-19, and perhaps limit neuroinflammation associated with long COVID.
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12
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Histamine Release in the Prefrontal Cortex Excites Fast-Spiking Interneurons while GABA Released from the Same Axons Inhibits Pyramidal Cells. J Neurosci 2023; 43:187-198. [PMID: 36639899 PMCID: PMC9838703 DOI: 10.1523/jneurosci.0936-22.2022] [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: 05/16/2022] [Revised: 09/06/2022] [Accepted: 11/03/2022] [Indexed: 12/13/2022] Open
Abstract
We studied how histamine and GABA release from axons originating from the hypothalamic tuberomammillary nucleus (TMN) and projecting to the prefrontal cortex (PFC) influence circuit processing. We optostimulated histamine/GABA from genetically defined TMN axons that express the histidine decarboxylase gene (TMNHDC axons). Whole-cell recordings from PFC neurons in layer 2/3 of prelimbic, anterior cingulate, and infralimbic regions were used to monitor excitability before and after optostimulated histamine/GABA release in male and female mice. We found that histamine-GABA release influences the PFC through actions on distinct neuronal types: the histamine stimulates fast-spiking interneurons; and the released GABA enhances tonic (extrasynaptic) inhibition on pyramidal cells (PyrNs). For fast-spiking nonaccommodating interneurons, histamine released from TMNHDC axons induced additive gain changes, which were blocked by histamine H1 and H2 receptor antagonists. The excitability of other fast-spiking interneurons in the PFC was not altered. In contrast, the GABA released from TMNHDC axons predominantly produced divisive gain changes in PyrNs, increasing their resting input conductance, and decreasing the slope of the input-output relationship. This inhibitory effect on PyrNs was not blocked by histamine receptor antagonists but was blocked by GABAA receptor antagonists. Across the adult life span (from 3 to 18 months of age), the GABA released from TMNHDC axons in the PFC inhibited PyrN excitability significantly more in older mice. For individuals who maintain cognitive performance into later life, the increases in TMNHDC GABA modulation of PyrNs during aging could enhance information processing and be an adaptive mechanism to buttress cognition.SIGNIFICANCE STATEMENT The hypothalamus controls arousal state by releasing chemical neurotransmitters throughout the brain to modulate neuronal excitability. Evidence is emerging that the release of multiple types of neurotransmitters may have opposing actions on neuronal populations in key cortical regions. This study demonstrates for the first time that the neurotransmitters histamine and GABA are released in the prefrontal cortex from axons originating from the tuberomammillary nucleus of the hypothalamus. This work demonstrates how hypothalamic modulation of neuronal excitability is maintained throughout adult life, highlighting an unexpected aspect of the aging process that may help maintain cognitive abilities.
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Dumontier D, Mailhes-Hamon C, Supplisson S, Dieudonné S. Neurotransmitter content heterogeneity within an interneuron class shapes inhibitory transmission at a central synapse. Front Cell Neurosci 2023; 16:1060189. [PMID: 36687523 PMCID: PMC9846633 DOI: 10.3389/fncel.2022.1060189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Accepted: 12/05/2022] [Indexed: 01/06/2023] Open
Abstract
Neurotransmitter content is deemed the most basic defining criterion for neuronal classes, contrasting with the intercellular heterogeneity of many other molecular and functional features. Here we show, in the adult mouse brain, that neurotransmitter content variegation within a neuronal class is a component of its functional heterogeneity. Golgi cells (GoCs), the well-defined class of cerebellar interneurons inhibiting granule cells (GrCs), contain cytosolic glycine, accumulated by the neuronal transporter GlyT2, and GABA in various proportions. By performing acute manipulations of cytosolic GABA and glycine supply, we find that competition of glycine with GABA reduces the charge of IPSC evoked in GrCs and, more specifically, the amplitude of a slow component of the IPSC decay. We then pair GrCs recordings with optogenetic stimulations of single GoCs, which preserve the intracellular transmitter mixed content. We show that the strength and decay kinetics of GrCs IPSCs, which are entirely mediated by GABAA receptors, are negatively correlated to the presynaptic expression of GlyT2 by GoCs. We isolate a slow spillover component of GrCs inhibition that is also affected by the expression of GlyT2, leading to a 56% decrease in relative charge. Our results support the hypothesis that presynaptic loading of glycine negatively impacts the GABAergic transmission in mixed interneurons, most likely through a competition for vesicular filling. We discuss how the heterogeneity of neurotransmitter supply within mixed interneurons like the GoC class may provide a presynaptic mechanism to tune the gain of microcircuits such as the granular layer, thereby expanding the realm of their possible dynamic behaviors.
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14
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Assis AD, Chiarotto GB, da Silva NS, Simões GF, Oliveira ALR. Pregabalin synchronizes the regeneration of nerve and muscle fibers optimizing the gait recovery of MDX dystrophic mice. FASEB J 2022; 36:e22511. [PMID: 35998000 DOI: 10.1096/fj.202200411rr] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 08/04/2022] [Accepted: 08/09/2022] [Indexed: 12/24/2022]
Abstract
Duchenne muscular dystrophy (DMD) is an X-linked genetic disorder induced by mutations in the dystrophin gene, leading to a degeneration of muscle fibers, triggering retrograde immunomodulatory, and degenerative events in the central nervous system. Thus, neuroprotective drugs such as pregabalin (PGB) can improve motor function by modulating plasticity, together with anti-inflammatory effects. The present work aimed to study the effects of PGB on axonal regeneration after axotomy in dystrophic and non-dystrophic mice. For that, MDX and C57BL/10 mouse strains were subjected to peripheral nerve damage and were treated with PGB (30 mg/kg/day, i.p.) for 28 consecutive days. The treatment was carried out in mice as soon as they completed 5 weeks of life, 1 week before the lesion, corresponding to the peak period of muscle degeneration in the MDX strain. Six-week-old mice were submitted to unilateral sciatic nerve crush and were sacrificed in the 9th week of age. The ipsi and contralateral sciatic nerves were processed for immunohistochemistry and qRT-PCR, evaluating the expression of proteins and gene transcripts related to neuronal and Schwann cell activity. Cranial tibial muscles were dissected for evaluation of neuromuscular junctions using α-bungarotoxin, and the myelinated axons of the sciatic nerve were analyzed by morphometry. The recovery of motor function was monitored throughout the treatment through tests of forced locomotion (rotarod) and spontaneous walking track test (Catwalk system). The results show that treatment with PGB reduced the retrograde cyclic effects of muscle degeneration/regeneration on the nervous system. This fact was confirmed after peripheral nerve injury, showing better adaptation and response of neurons and glia for rapid axonal regeneration, with efficient muscle targeting and regain of function. No side effects of PGB treatment were observed, and the expression of pro-regenerative proteins in neurons and Schwann cells was upregulated. Morphometry of the axons was in line with the preservation of motor endplates, resulting in enhanced performance of dystrophic animals. Overall, the present data indicate that pregabalin is protective and enhances regeneration of the SNP during the development of DMD, improving motor function, which can, in turn, be translated to the clinic.
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Affiliation(s)
- Alex Dias Assis
- Laboratory of Nerve Regeneration, University of Campinas - UNICAMP, Campinas, Brazil
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15
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Nimitvilai-Roberts S, Woodward JJ. The ethanol inhibition of basolateral amygdala neuron spiking is mediated by a γ-aminobutyric acid type A-mediated tonic current. Alcohol Clin Exp Res 2022; 46:1665-1676. [PMID: 35915568 PMCID: PMC9509443 DOI: 10.1111/acer.14918] [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: 05/12/2022] [Revised: 07/19/2022] [Accepted: 07/28/2022] [Indexed: 01/31/2023]
Abstract
BACKGROUND The basolateral nucleus of the amygdala (BLA) plays an important role in the development of fear and anxiety-related behaviors. The BLA receives inputs from all sensory stimuli. After processing those stimuli, BLA neurons signal neurons within the central amygdala and other brain regions, including the ventral and dorsal striatum and frontal cortex. Studies suggest that the BLA is involved in drug dependence and in the reinforcing actions of ethanol. For example, acute exposure to ethanol reduces anxiety, while withdrawal from chronic ethanol exposure alters BLA synaptic transmission, which increases anxiety, a common underlying cause of relapse. Exposure to and withdrawal from chronic alcohol also disrupts many brain areas that connect with the BLA. Despite these important findings, the acute actions of alcohol on the intrinsic excitability of BLA neurons have not been fully characterized. METHODS Brain slices containing the BLA were prepared from adult C57BL/6J male mice. Whole-cell and sharp electrode electrophysiological recordings were performed to characterize the effects of acute ethanol on BLA neuronal and astrocyte function, respectively. RESULTS Ethanol inhibited action potential (AP) firing of BLA neurons but had no effect on BLA astrocyte resting membrane potential. The ethanol-induced inhibition of firing was concentration-dependent (11 to 66 mM) and accompanied by a reduction in the input resistance and an increase in the rheobase of BLA neurons. The inhibitory effect of ethanol was suppressed by picrotoxin, which blocks both γ-aminobutyric acid type A (GABAA ) and glycine receptors, but not by the selective glycine receptor antagonist strychnine, which suggests an involvement of GABAA receptors. Ethanol did not affect spontaneous inhibitory postsynaptic currents suggesting that the inhibition of BLA neuronal excitability by ethanol was not due to an increase in GABAA -mediated synaptic transmission. However, acute ethanol enhanced the amplitude of the holding current of BLA neurons, an effect that was prevented by picrotoxin, which by itself reduced the holding current. CONCLUSIONS These results suggest that BLA neurons express a GABA-mediated tonic current that is enhanced by acute ethanol, which leads to reduced excitability of BLA neurons.
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Affiliation(s)
| | - John J. Woodward
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC 29425
- Department of Psychiatry and Behavioral Sciences, Addiction Sciences Division, Medical University of South Carolina, Charleston, SC 29425
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16
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Hoshino O, Zheng M, Fukuoka Y. Effect of cortical extracellular GABA on motor response. J Comput Neurosci 2022; 50:375-393. [PMID: 35695984 DOI: 10.1007/s10827-022-00821-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2021] [Revised: 04/26/2022] [Accepted: 05/23/2022] [Indexed: 11/26/2022]
Abstract
To elucidate how the flattening of sensory tuning due to a deficit in tonic inhibition slows motor responses, we simulated a neural network model in which a sensory cortical network ([Formula: see text]) and a motor cortical network ([Formula: see text]) are reciprocally connected, and the [Formula: see text] projects to spinal motoneurons (Mns). The [Formula: see text] was presented with a feature stimulus and the reaction time of Mns was measured. The flattening of sensory tuning in [Formula: see text] caused by decreasing the concentration of gamma-aminobutyric acid (GABA) in extracellular space resulted in a decrease in the stimulus-sensitive [Formula: see text] pyramidal cell activity while increasing the stimulus-insensitive [Formula: see text] pyramidal cell activity, thereby prolonging the reaction time of Mns to the applied feature stimulus. We suggest that a reduction in extracellular GABA concentration in sensory cortex may interfere with selective activation in motor cortex, leading to slowing the activation of spinal motoneurons and therefore to slowing motor responses.
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Affiliation(s)
- Osamu Hoshino
- Independent Researcher, 505-9 Namiyanagi, Hanno, Saitama, 357-0021, Japan.
| | - Meihong Zheng
- Department of Psychology, Tsinghua University, Beijing, 100084, People's Republic of China
| | - Yasuhiro Fukuoka
- Department of Mechanical Systems Engineering, Ibaraki University, 4-12-1 Nakanarusawa, Hitachi, Ibaraki, 316-8511, Japan
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17
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Abstract
The cerebellar cortex is an important system for relating neural circuits and learning. Its promise reflects the longstanding idea that it contains simple, repeated circuit modules with only a few cell types and a single plasticity mechanism that mediates learning according to classical Marr-Albus models. However, emerging data have revealed surprising diversity in neuron types, synaptic connections, and plasticity mechanisms, both locally and regionally within the cerebellar cortex. In light of these findings, it is not surprising that attempts to generate a holistic model of cerebellar learning across different behaviors have not been successful. While the cerebellum remains an ideal system for linking neuronal function with behavior, it is necessary to update the cerebellar circuit framework to achieve its great promise. In this review, we highlight recent advances in our understanding of cerebellar-cortical cell types, synaptic connections, signaling mechanisms, and forms of plasticity that enrich cerebellar processing.
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Affiliation(s)
- Court Hull
- Department of Neurobiology, Duke University School of Medicine, Durham, North Carolina, USA;
| | - Wade G Regehr
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, USA;
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18
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Sa M, Lee JM, Park MG, Lim J, Kim JMJ, Koh W, Yoon BE, Lee CJ. Unaltered Tonic Inhibition in the Arcuate Nucleus of Diet-induced Obese Mice. Exp Neurobiol 2022; 31:147-157. [PMID: 35786638 PMCID: PMC9272119 DOI: 10.5607/en22014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2022] [Revised: 05/17/2022] [Accepted: 05/18/2022] [Indexed: 11/19/2022] Open
Abstract
The principal inhibitory transmitter, γ-aminobutyric acid (GABA), is critical for maintaining hypothalamic homeostasis and released from neurons phasically, as well as from astrocytes tonically. Although astrocytes in the arcuate nucleus (ARC) of the hypothalamus are shown to transform into reactive astrocytes, the tonic inhibition by astrocytic GABA has not been adequately investigated in diet-induced obesity (DIO). Here, we investigated the expression of monoamine oxidase-B (MAOB), a GABA-synthesizing enzyme, in reactive astrocytes in obese mice. We observed that a chronic high-fat diet (HFD) significantly increased astrocytic MAOB and cellular GABA content, along with enhanced hypertrophy of astrocytes in the ARC. Unexpectedly, we found that the level of tonic GABA was unaltered in chronic HFD mice using whole-cell patch-clamp recordings in the ARC. Furthermore, the GABA-induced current was increased with elevated GABAA receptor α5 (GABRA5) expression. Surprisingly, we found that a nonselective GABA transporter (GAT) inhibitor, nipecotic acid (NPA)-induced current was significantly increased in chronic HFD mice. We observed that GAT1 inhibitor, NO711-induced current was significantly increased, whereas GAT3 inhibitor, SNAP5114-induced current was not altered. The unexpected unaltered tonic inhibition was due to an increase of GABA clearance in the ARC by neuronal GAT1 rather than astrocytic GAT3. These results imply that increased astrocytic GABA synthesis and neuronal GABAA receptor were compensated by GABA clearance, resulting in unaltered tonic GABA inhibition in the ARC of the hypothalamus in obese mice. Taken together, GABA-related molecular pathways in the ARC dynamically regulate the tonic inhibition to maintain hypothalamic homeostasis against the HFD challenge.
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Affiliation(s)
- Moonsun Sa
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Korea
- Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon 34126, Korea
| | - Jung Moo Lee
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Korea
- Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon 34126, Korea
| | - Mingu Gordon Park
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Korea
- Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon 34126, Korea
| | - Jiwoon Lim
- Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon 34126, Korea
- IBS School, University of Science and Technology (UST), Daejeon 34126, Korea
| | | | - Wuhyun Koh
- Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon 34126, Korea
| | - Bo-Eun Yoon
- Department of Molecular Biology, Dankook University, Cheonan 31116, Korea
| | - C. Justin Lee
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Korea
- Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon 34126, Korea
- IBS School, University of Science and Technology (UST), Daejeon 34126, Korea
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19
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Savić B, Murphy D, Japundžić-Žigon N. The Paraventricular Nucleus of the Hypothalamus in Control of Blood Pressure and Blood Pressure Variability. Front Physiol 2022; 13:858941. [PMID: 35370790 PMCID: PMC8966844 DOI: 10.3389/fphys.2022.858941] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 02/15/2022] [Indexed: 12/26/2022] Open
Abstract
The paraventricular nucleus (PVN) is a highly organized structure of the hypothalamus that has a key role in regulating cardiovascular and osmotic homeostasis. Functionally, the PVN is divided into autonomic and neuroendocrine (neurosecretory) compartments, both equally important for maintaining blood pressure (BP) and body fluids in the physiological range. Neurosecretory magnocellular neurons (MCNs) of the PVN are the main source of the hormones vasopressin (VP), responsible for water conservation and hydromineral balance, and oxytocin (OT), involved in parturition and milk ejection during lactation. Further, neurosecretory parvocellular neurons (PCNs) take part in modulation of the hypothalamic–pituitary–adrenal axis and stress responses. Additionally, the PVN takes central place in autonomic adjustment of BP to environmental challenges and contributes to its variability (BPV), underpinning the PVN as an autonomic master controller of cardiovascular function. Autonomic PCNs of the PVN modulate sympathetic outflow toward heart, blood vessels and kidneys. These pre-autonomic neurons send projections to the vasomotor nucleus of rostral ventrolateral medulla and to intermediolateral column of the spinal cord, where postganglionic fibers toward target organs arise. Also, PVN PCNs synapse with NTS neurons which are the end-point of baroreceptor primary afferents, thus, enabling the PVN to modify the function of baroreflex. Neuroendocrine and autonomic parts of the PVN are segregated morphologically but they work in concert when the organism is exposed to environmental challenges via somatodendritically released VP and OT by MCNs. The purpose of this overview is to address both neuroendocrine and autonomic PVN roles in BP and BPV regulation.
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Affiliation(s)
- Bojana Savić
- Laboratory for Cardiovascular Pharmacology and Toxicology, Faculty of Medicine, Institute of Pharmacology, Clinical Pharmacology and Toxicology, University of Belgrade, Belgrade, Serbia
| | - David Murphy
- Molecular Neuroendocrinology Research Group, Bristol Medical School, Translational Health Sciences, University of Bristol, Bristol, United Kingdom
| | - Nina Japundžić-Žigon
- Laboratory for Cardiovascular Pharmacology and Toxicology, Faculty of Medicine, Institute of Pharmacology, Clinical Pharmacology and Toxicology, University of Belgrade, Belgrade, Serbia
- *Correspondence: Nina Japundžić-Žigon,
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20
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Prisco L, Deimel SH, Yeliseyeva H, Fiala A, Tavosanis G. The anterior paired lateral neuron normalizes odour-evoked activity in the Drosophila mushroom body calyx. eLife 2021; 10:e74172. [PMID: 34964714 PMCID: PMC8741211 DOI: 10.7554/elife.74172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Accepted: 12/28/2021] [Indexed: 11/25/2022] Open
Abstract
To identify and memorize discrete but similar environmental inputs, the brain needs to distinguish between subtle differences of activity patterns in defined neuronal populations. The Kenyon cells (KCs) of the Drosophila adult mushroom body (MB) respond sparsely to complex olfactory input, a property that is thought to support stimuli discrimination in the MB. To understand how this property emerges, we investigated the role of the inhibitory anterior paired lateral (APL) neuron in the input circuit of the MB, the calyx. Within the calyx, presynaptic boutons of projection neurons (PNs) form large synaptic microglomeruli (MGs) with dendrites of postsynaptic KCs. Combining electron microscopy (EM) data analysis and in vivo calcium imaging, we show that APL, via inhibitory and reciprocal synapses targeting both PN boutons and KC dendrites, normalizes odour-evoked representations in MGs of the calyx. APL response scales with the PN input strength and is regionalized around PN input distribution. Our data indicate that the formation of a sparse code by the KCs requires APL-driven normalization of their MG postsynaptic responses. This work provides experimental insights on how inhibition shapes sensory information representation in a higher brain centre, thereby supporting stimuli discrimination and allowing for efficient associative memory formation.
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Affiliation(s)
- Luigi Prisco
- Dynamics of neuronal circuits, German Center for Neurodegenerative Diseases (DZNE)BonnGermany
| | | | - Hanna Yeliseyeva
- Dynamics of neuronal circuits, German Center for Neurodegenerative Diseases (DZNE)BonnGermany
| | - André Fiala
- Department of Molecular Neurobiology of Behavior, University of GöttingenGöttingenGermany
| | - Gaia Tavosanis
- Dynamics of neuronal circuits, German Center for Neurodegenerative Diseases (DZNE)BonnGermany
- LIMES, Rheinische Friedrich Wilhelms Universität BonnBonnGermany
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21
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Bukina ES, Kondratyev NV, Kozin SV, Golimbet VE, Artyuhov AS, Dashinimaev EB. SLC6A1 and Neuropsychiatric Diseases: The Role of Mutations and Prospects for Treatment with Genome Editing Systems. NEUROCHEM J+ 2021. [DOI: 10.1134/s1819712421040048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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22
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Tonic GABA A Receptor-Mediated Currents of Human Cortical GABAergic Interneurons Vary Amongst Cell Types. J Neurosci 2021; 41:9702-9719. [PMID: 34667071 PMCID: PMC8612645 DOI: 10.1523/jneurosci.0175-21.2021] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 09/08/2021] [Accepted: 09/10/2021] [Indexed: 12/03/2022] Open
Abstract
Persistent anion conductances through GABAA receptors (GABAARs) are important modulators of neuronal excitability. However, it is currently unknown how the amplitudes of these currents vary among different cell types in the human neocortex, particularly among diverse GABAergic interneurons. We have recorded 101 interneurons in and near layer 1 from cortical tissue surgically resected from both male and female patients, visualized 84 of them and measured tonic GABAAR currents in 48 cells with an intracellular [Cl–] of 65 mm and in the presence of 5 μm GABA. We compare these tonic currents among five groups of interneurons divided by firing properties and four types of interneuron defined by axonal distributions; rosehip, neurogliaform, stalked-bouton, layer 2–3 innervating and a pool of other cells. Interestingly, the rosehip cell, a type of interneuron only described thus far in human tissue, and layer 2–3 innervating cells exhibit larger tonic currents than other layer 1 interneurons, such as neurogliaform and stalked-bouton cells; the latter two groups showing no difference. The positive allosteric modulators of GABAARs allopregnanolone and DS2 also induced larger current shifts in the rosehip and layer 2–3 innervating cells, consistent with higher expression of the δ subunit of the GABAAR in these neurons. We have also examined how patient parameters, such as age, seizures, type of cancer and anticonvulsant treatment may alter tonic inhibitory currents in human neurons. The cell type-specific differences in tonic inhibitory currents could potentially be used to selectively modulate cortical circuitry. SIGNIFICANCE STATEMENT Tonic currents through GABAA receptors (GABAARs) are a potential therapeutic target for a number of neurologic and psychiatric conditions. Here, we show that these currents in human cerebral cortical GABAergic neurons display cell type-specific differences in their amplitudes which implies differential modulation of their excitability. Additionally, we examine whether the amplitudes of the tonic currents measured in our study show any differences between patient populations, finding some evidence that age, seizures, type of cancer, and anticonvulsant treatment may alter tonic inhibition in human tissue. These results advance our understanding of how pathology affects neuronal excitability and could potentially be used to selectively modulate cortical circuitry.
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23
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Sexton CA, Penzinger R, Mortensen M, Bright DP, Smart TG. Structural determinants and regulation of spontaneous activity in GABA A receptors. Nat Commun 2021; 12:5457. [PMID: 34526505 PMCID: PMC8443696 DOI: 10.1038/s41467-021-25633-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 08/24/2021] [Indexed: 11/25/2022] Open
Abstract
GABAA receptors are vital for controlling neuronal excitability and can display significant levels of constitutive activity that contributes to tonic inhibition. However, the mechanisms underlying spontaneity are poorly understood. Here we demonstrate a strict requirement for β3 subunit incorporation into receptors for spontaneous gating, facilitated by α4, α6 and δ subunits. The crucial molecular determinant involves four amino acids (GKER) in the β3 subunit's extracellular domain, which interacts with adjacent receptor subunits to promote transition to activated, open channel conformations. Spontaneous activity is further regulated by β3 subunit phosphorylation and by allosteric modulators including neurosteroids and benzodiazepines. Promoting spontaneous activity reduced neuronal excitability, indicating that spontaneous currents will alter neural network activity. This study demonstrates how regional diversity in GABAA receptor isoform, protein kinase activity, and neurosteroid levels, can impact on tonic inhibition through the modulation of spontaneous GABAA receptor gating.
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Affiliation(s)
- Craig A Sexton
- Department of Neuroscience, Physiology & Pharmacology, UCL, London, UK
| | - Reka Penzinger
- Department of Neuroscience, Physiology & Pharmacology, UCL, London, UK
| | - Martin Mortensen
- Department of Neuroscience, Physiology & Pharmacology, UCL, London, UK
| | - Damian P Bright
- Department of Neuroscience, Physiology & Pharmacology, UCL, London, UK
| | - Trevor G Smart
- Department of Neuroscience, Physiology & Pharmacology, UCL, London, UK.
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24
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Guo C, Rudolph S, Neuwirth ME, Regehr WG. Purkinje cell outputs selectively inhibit a subset of unipolar brush cells in the input layer of the cerebellar cortex. eLife 2021; 10:e68802. [PMID: 34369877 PMCID: PMC8352585 DOI: 10.7554/elife.68802] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 07/23/2021] [Indexed: 11/13/2022] Open
Abstract
Circuitry of the cerebellar cortex is regionally and functionally specialized. Unipolar brush cells (UBCs), and Purkinje cell (PC) synapses made by axon collaterals in the granular layer, are both enriched in areas that control balance and eye movement. Here, we find a link between these specializations in mice: PCs preferentially inhibit metabotropic glutamate receptor type 1 (mGluR1)-expressing UBCs that respond to mossy fiber (MF) inputs with long lasting increases in firing, but PCs do not inhibit mGluR1-lacking UBCs. PCs inhibit about 29% of mGluR1-expressing UBCs by activating GABAA receptors (GABAARs) and inhibit almost all mGluR1-expressing UBCs by activating GABAB receptors (GABABRs). PC to UBC synapses allow PC output to regulate the input layer of the cerebellar cortex in diverse ways. Based on optogenetic studies and a small number of paired recordings, GABAAR-mediated feedback is fast and unreliable. GABABR-mediated inhibition is slower and is sufficiently large to strongly influence the input-output transformations of mGluR1-expressing UBCs.
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Affiliation(s)
- Chong Guo
- Department of Neurobiology, Harvard Medical SchoolBostonUnited States
| | - Stephanie Rudolph
- Department of Neurobiology, Harvard Medical SchoolBostonUnited States
| | - Morgan E Neuwirth
- Department of Neurobiology, Harvard Medical SchoolBostonUnited States
| | - Wade G Regehr
- Department of Neurobiology, Harvard Medical SchoolBostonUnited States
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25
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Delgado‐Lezama R, Bravo‐Hernández M, Franco‐Enzástiga Ú, De la Luz‐Cuellar YE, Alvarado‐Cervantes NS, Raya‐Tafolla G, Martínez‐Zaldivar LA, Vargas‐Parada A, Rodríguez‐Palma EJ, Vidal‐Cantú GC, Guzmán‐Priego CG, Torres‐López JE, Murbartián J, Felix R, Granados‐Soto V. The role of spinal cord extrasynaptic α 5 GABA A receptors in chronic pain. Physiol Rep 2021; 9:e14984. [PMID: 34409771 PMCID: PMC8374381 DOI: 10.14814/phy2.14984] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2021] [Revised: 06/25/2021] [Accepted: 06/29/2021] [Indexed: 11/24/2022] Open
Abstract
Chronic pain is an incapacitating condition that affects a large population worldwide. Until now, there is no drug treatment to relieve it. The impairment of GABAergic inhibition mediated by GABAA receptors (GABAA R) is considered a relevant factor in mediating chronic pain. Even though both synaptic and extrasynaptic GABAA inhibition are present in neurons that process nociceptive information, the latter is not considered relevant as a target for the development of pain treatments. In particular, the extrasynaptic α5 GABAA Rs are expressed in laminae I-II of the spinal cord neurons, sensory neurons, and motoneurons. In this review, we discuss evidence showing that blockade of the extrasynaptic α5 GABAA Rs reduces mechanical allodynia in various models of chronic pain and restores the associated loss of rate-dependent depression of the Hoffmann reflex. Furthermore, in healthy animals, extrasynaptic α5 GABAA R blockade induces both allodynia and hyperalgesia. These results indicate that this receptor may have an antinociceptive and pronociceptive role in healthy and chronic pain-affected animals, respectively. We propose a hypothesis to explain the relevant role of the extrasynaptic α5 GABAA Rs in the processing of nociceptive information. The data discussed here strongly suggest that this receptor could be a valid pharmacological target to treat chronic pain states.
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Affiliation(s)
| | - Mariana Bravo‐Hernández
- Neuroregeneration LaboratoryDepartment of AnesthesiologyUniversity of CaliforniaSan Diego, La JollaCAUSA
| | | | | | | | | | | | | | | | | | - Crystell G. Guzmán‐Priego
- Mechanisms of Pain LaboratoryDivisión Académica de Ciencias de la SaludUniversidad Juárez Autónoma de Tabasco, VillahermosaTabascoMexico
| | - Jorge E. Torres‐López
- Mechanisms of Pain LaboratoryDivisión Académica de Ciencias de la SaludUniversidad Juárez Autónoma de Tabasco, VillahermosaTabascoMexico
- Hospital Regional de Alta Especialidad “Dr. Juan Graham Casasús”, VillahermosaTabascoMexico
| | | | - Ricardo Felix
- Departamento de Biología CelularCinvestavMexico CityMexico
| | - Vinicio Granados‐Soto
- Neurobiology of Pain LaboratoryDepartamento de FarmacobiologíaCinvestavMexico CityMexico
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26
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Electrophysiology of ionotropic GABA receptors. Cell Mol Life Sci 2021; 78:5341-5370. [PMID: 34061215 PMCID: PMC8257536 DOI: 10.1007/s00018-021-03846-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 04/02/2021] [Accepted: 04/23/2021] [Indexed: 10/30/2022]
Abstract
GABAA receptors are ligand-gated chloride channels and ionotropic receptors of GABA, the main inhibitory neurotransmitter in vertebrates. In this review, we discuss the major and diverse roles GABAA receptors play in the regulation of neuronal communication and the functioning of the brain. GABAA receptors have complex electrophysiological properties that enable them to mediate different types of currents such as phasic and tonic inhibitory currents. Their activity is finely regulated by membrane voltage, phosphorylation and several ions. GABAA receptors are pentameric and are assembled from a diverse set of subunits. They are subdivided into numerous subtypes, which differ widely in expression patterns, distribution and electrical activity. Substantial variations in macroscopic neural behavior can emerge from minor differences in structure and molecular activity between subtypes. Therefore, the diversity of GABAA receptors widens the neuronal repertoire of responses to external signals and contributes to shaping the electrical activity of neurons and other cell types.
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Hammoud H, Netsyk O, Tafreshiha AS, Korol SV, Jin Z, Li J, Birnir B. Insulin differentially modulates GABA signalling in hippocampal neurons and, in an age-dependent manner, normalizes GABA-activated currents in the tg-APPSwe mouse model of Alzheimer's disease. Acta Physiol (Oxf) 2021; 232:e13623. [PMID: 33559388 DOI: 10.1111/apha.13623] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 01/29/2021] [Accepted: 02/03/2021] [Indexed: 02/06/2023]
Abstract
AIM We examined if tonic γ-aminobutyric acid (GABA)-activated currents in primary hippocampal neurons were modulated by insulin in wild-type and tg-APPSwe mice, an Alzheimer's disease (AD) model. METHODS GABA-activated currents were recorded in dentate gyrus (DG) granule cells and CA3 pyramidal neurons in hippocampal brain slices, from 8 to 10 weeks old (young) wild-type mice and in dorsal DG granule cells in adult, 5-6 and 10-12 (aged) months old wild-type and tg-APPSwe mice, in the absence or presence of insulin, by whole-cell patch-clamp electrophysiology. RESULTS In young mice, insulin (1 nmol/L) enhanced the total spontaneous inhibitory postsynaptic current (sIPSCT ) density in both dorsal and ventral DG granule cells. The extrasynaptic current density was only increased by insulin in dorsal CA3 pyramidal neurons. In absence of action potentials, insulin enhanced DG granule cells and dorsal CA3 pyramidal neurons miniature IPSC (mIPSC) frequency, consistent with insulin regulation of presynaptic GABA release. sIPSCT densities in DG granule cells were similar in wild-type and tg-APPSwe mice at 5-6 months but significantly decreased in aged tg-APPSwe mice where insulin normalized currents to wild-type levels. The extrasynaptic current density was increased in tg-APPSwe mice relative to wild-type littermates but, only in aged tg-APPSwe mice did insulin decrease and normalize the current. CONCLUSION Insulin effects on GABA signalling in hippocampal neurons are selective while multifaceted and context-based. Not only is the response to insulin related to cell-type, hippocampal axis-location, age of animals and disease but also to the subtype of neuronal inhibition involved, synaptic or extrasynaptic GABAA receptors-activated currents.
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Affiliation(s)
- Hayma Hammoud
- Department of Medical Cell Biology Uppsala University Uppsala Sweden
| | - Olga Netsyk
- Department of Medical Cell Biology Uppsala University Uppsala Sweden
| | | | - Sergiy V. Korol
- Department of Medical Cell Biology Uppsala University Uppsala Sweden
| | - Zhe Jin
- Department of Medical Cell Biology Uppsala University Uppsala Sweden
| | - Jin‐Ping Li
- Department of Medical Biochemistry and Microbiology Uppsala University Uppsala Sweden
| | - Bryndis Birnir
- Department of Medical Cell Biology Uppsala University Uppsala Sweden
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Gurnani H, Silver RA. Multidimensional population activity in an electrically coupled inhibitory circuit in the cerebellar cortex. Neuron 2021; 109:1739-1753.e8. [PMID: 33848473 PMCID: PMC8153252 DOI: 10.1016/j.neuron.2021.03.027] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 01/20/2021] [Accepted: 03/20/2021] [Indexed: 01/05/2023]
Abstract
Inhibitory neurons orchestrate the activity of excitatory neurons and play key roles in circuit function. Although individual interneurons have been studied extensively, little is known about their properties at the population level. Using random-access 3D two-photon microscopy, we imaged local populations of cerebellar Golgi cells (GoCs), which deliver inhibition to granule cells. We show that population activity is organized into multiple modes during spontaneous behaviors. A slow, network-wide common modulation of GoC activity correlates with the level of whisking and locomotion, while faster (<1 s) differential population activity, arising from spatially mixed heterogeneous GoC responses, encodes more precise information. A biologically detailed GoC circuit model reproduced the common population mode and the dimensionality observed experimentally, but these properties disappeared when electrical coupling was removed. Our results establish that local GoC circuits exhibit multidimensional activity patterns that could be used for inhibition-mediated adaptive gain control and spatiotemporal patterning of downstream granule cells.
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Affiliation(s)
- Harsha Gurnani
- Department of Neuroscience, Physiology, and Pharmacology, University College London, London WC1E 6BT, UK
| | - R Angus Silver
- Department of Neuroscience, Physiology, and Pharmacology, University College London, London WC1E 6BT, UK.
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Rudolph S, Guo C, Pashkovski SL, Osorno T, Gillis WF, Krauss JM, Nyitrai H, Flaquer I, El-Rifai M, Datta SR, Regehr WG. Cerebellum-Specific Deletion of the GABA A Receptor δ Subunit Leads to Sex-Specific Disruption of Behavior. Cell Rep 2021; 33:108338. [PMID: 33147470 PMCID: PMC7700496 DOI: 10.1016/j.celrep.2020.108338] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 08/04/2020] [Accepted: 10/08/2020] [Indexed: 12/19/2022] Open
Abstract
Granule cells (GCs) of the cerebellar input layer express high-affinity δ GABAA subunit-containing GABAA receptors (δGABAARs) that respond to ambient GABA levels and context-dependent neuromodulators like steroids. We find that GC-specific deletion of δGABAA (cerebellar [cb] δ knockout [KO]) decreases tonic inhibition, makes GCs hyperexcitable, and in turn, leads to differential activation of cb output regions as well as many cortical and subcortical brain areas involved in cognition, anxiety-like behaviors, and the stress response. Cb δ KO mice display deficits in many behaviors, but motor function is normal. Strikingly, δGABAA deletion alters maternal behavior as well as spontaneous, stress-related, and social behaviors specifically in females. Our findings establish that δGABAARs enable the cerebellum to control diverse behaviors not previously associated with the cerebellum in a sex-dependent manner. These insights may contribute to a better understanding of the mechanisms that underlie behavioral abnormalities in psychiatric and neurodevelopmental disorders that display a gender bias. Rudolph et al. show that deletion of the neuromodulator and hormone-sensitive δGABAA receptor subunit from cerebellar granule cells results in anxiety-like behaviors and female-specific deficits in social behavior and maternal care. δGABAA deletion is associated with hyperexcitability of the cerebellar input layer and altered activation of many stress-related brain regions.
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Affiliation(s)
- Stephanie Rudolph
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Chong Guo
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Stan L Pashkovski
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Tomas Osorno
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Winthrop F Gillis
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Jeremy M Krauss
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Hajnalka Nyitrai
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Isabella Flaquer
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Mahmoud El-Rifai
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | | | - Wade G Regehr
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA.
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Balmer TS, Borges-Merjane C, Trussell LO. Incomplete removal of extracellular glutamate controls synaptic transmission and integration at a cerebellar synapse. eLife 2021; 10:e63819. [PMID: 33616036 PMCID: PMC7935485 DOI: 10.7554/elife.63819] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Accepted: 02/19/2021] [Indexed: 11/27/2022] Open
Abstract
Synapses of glutamatergic mossy fibers (MFs) onto cerebellar unipolar brush cells (UBCs) generate slow excitatory (ON) or inhibitory (OFF) postsynaptic responses dependent on the complement of glutamate receptors expressed on the UBC's large dendritic brush. Using mouse brain slice recording and computational modeling of synaptic transmission, we found that substantial glutamate is maintained in the UBC synaptic cleft, sufficient to modify spontaneous firing in OFF UBCs and tonically desensitize AMPARs of ON UBCs. The source of this ambient glutamate was spontaneous, spike-independent exocytosis from the MF terminal, and its level was dependent on activity of glutamate transporters EAAT1-2. Increasing levels of ambient glutamate shifted the polarity of evoked synaptic responses in ON UBCs and altered the phase of responses to in vivo-like synaptic activity. Unlike classical fast synapses, receptors at the UBC synapse are virtually always exposed to a significant level of glutamate, which varies in a graded manner during transmission.
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Affiliation(s)
- Timothy S Balmer
- Vollum Institute and Oregon Hearing Research Center, Oregon Health & Science UniversityPortlandUnited States
| | - Carolina Borges-Merjane
- Vollum Institute and Oregon Hearing Research Center, Oregon Health & Science UniversityPortlandUnited States
- Neuroscience Graduate Program, Vollum Institute, Oregon Health & Science UniversityPortlandUnited States
| | - Laurence O Trussell
- Vollum Institute and Oregon Hearing Research Center, Oregon Health & Science UniversityPortlandUnited States
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Tossell K, Dodhia RA, Galet B, Tkachuk O, Ungless MA. Tonic GABAergic inhibition, via GABA A receptors containing αβƐ subunits, regulates excitability of ventral tegmental area dopamine neurons. Eur J Neurosci 2021; 53:1722-1737. [PMID: 33522050 PMCID: PMC8651010 DOI: 10.1111/ejn.15133] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Revised: 12/15/2020] [Accepted: 01/18/2021] [Indexed: 12/13/2022]
Abstract
The activity of midbrain dopamine neurons is strongly regulated by fast synaptic inhibitory γ‐Aminobutyric acid (GABA)ergic inputs. There is growing evidence in other brain regions that low concentrations of ambient GABA can persistently activate certain subtypes of GABAA receptor to generate a tonic current. However, evidence for a tonic GABAergic current in midbrain dopamine neurons is limited. To address this, we conducted whole‐cell recordings from ventral tegmental area (VTA) dopamine neurons in brain slices from mice. We found that application of GABAA receptor antagonists decreased the holding current, indicating the presence of a tonic GABAergic input. Global increases in GABA release, induced by either a nitric oxide donor or inhibition of GABA uptake, further increased this tonic current. Importantly, prolonged inhibition of the firing activity of local GABAergic neurons abolished the tonic current. A combination of pharmacology and immunohistochemistry experiments suggested that, unlike common examples of tonic inhibition, this current may be mediated by a relatively unusual combination of α4βƐ subunits. Lastly, we found that the tonic current reduced excitability in dopamine neurons suggesting a subtractive effect on firing activity.
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Affiliation(s)
- Kyoko Tossell
- MRC London Institute of Medical Sciences (LMS), London, UK.,Institute of Clinical Sciences (ICS), Faculty of Medicine, Imperial College London, London, UK
| | - Rakesh A Dodhia
- MRC London Institute of Medical Sciences (LMS), London, UK.,Institute of Clinical Sciences (ICS), Faculty of Medicine, Imperial College London, London, UK
| | - Benjamin Galet
- MRC London Institute of Medical Sciences (LMS), London, UK.,Institute of Clinical Sciences (ICS), Faculty of Medicine, Imperial College London, London, UK
| | - Olga Tkachuk
- MRC London Institute of Medical Sciences (LMS), London, UK.,Institute of Clinical Sciences (ICS), Faculty of Medicine, Imperial College London, London, UK
| | - Mark A Ungless
- MRC London Institute of Medical Sciences (LMS), London, UK.,Institute of Clinical Sciences (ICS), Faculty of Medicine, Imperial College London, London, UK
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Gilbert M, Chris Miall R. How and Why the Cerebellum Recodes Input Signals: An Alternative to Machine Learning. Neuroscientist 2021; 28:206-221. [PMID: 33559532 PMCID: PMC9136479 DOI: 10.1177/1073858420986795] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Mossy fiber input to the cerebellum is received by granule cells where it is thought to be recoded into internal signals received by Purkinje cells, which alone carry the output of the cerebellar cortex. In any neural network, variables are contained in groups of signals as well as signals themselves—which cells are active and how many, for example, and statistical variables coded in rates, such as the mean and range, and which rates are strongly represented, in a defined population. We argue that the primary function of recoding is to confine translation to an effect of some variables and not others—both where input is recoded into internal signals and the translation downstream of internal signals into an effect on Purkinje cells. The cull of variables is harsh. Internal signaling is group coded. This allows coding to exploit statistics for a reliable and precise effect despite needing to work with high-dimensional input which is a highly unpredictably variable. An important effect is to normalize eclectic input signals, so that the basic, repeating cerebellar circuit, preserved across taxa, does not need to specialize (within regional variations). With this model, there is no need to slavishly conserve or compute data coded in single signals. If we are correct, a learning algorithm—for years, a mainstay of cerebellar modeling—would be redundant.
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Affiliation(s)
- Mike Gilbert
- School of Psychology, University of Birmingham, Birmingham, UK
| | - R Chris Miall
- School of Psychology, University of Birmingham, Birmingham, UK
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Bird LM, Ochoa-Lubinoff C, Tan WH, Heimer G, Melmed RD, Rakhit A, Visootsak J, During MJ, Holcroft C, Burdine RD, Kolevzon A, Thibert RL. The STARS Phase 2 Study: A Randomized Controlled Trial of Gaboxadol in Angelman Syndrome. Neurology 2020; 96:e1024-e1035. [PMID: 33443117 PMCID: PMC8055330 DOI: 10.1212/wnl.0000000000011409] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Accepted: 10/12/2020] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE To evaluate safety and tolerability and exploratory efficacy end points for gaboxadol (OV101) compared with placebo in individuals with Angelman syndrome (AS). METHODS Gaboxadol is a highly selective orthosteric agonist that activates δ-subunit-containing extrasynaptic γ-aminobutyric acid type A (GABAA) receptors. In a multicenter, double-blind, placebo-controlled, parallel-group trial, adolescent and adult individuals with a molecular diagnosis of AS were randomized (1:1:1) to 1 of 3 dosing regimens for a duration of 12 weeks: placebo morning dose and gaboxadol 15 mg evening dose (qd), gaboxadol 10 mg morning dose and 15 mg evening dose (bid), or placebo morning and evening dose. Safety and tolerability were monitored throughout the study. Prespecified exploratory efficacy end points included adapted Clinical Global Impression-Severity and Clinical Global Impression-Improvement (CGI-I) scales, which documented the clinical severity at baseline and change after treatment, respectively. RESULTS Eighty-eight individuals were randomized. Of 87 individuals (aged 13-45 years) who received at least 1 dose of study drug, 78 (90%) completed the study. Most adverse events (AEs) were mild to moderate, and no life-threatening AEs were reported. Efficacy of gaboxadol, as measured by CGI-I improvement in an exploratory analysis, was observed in gaboxadol qd vs placebo (p = 0.0006). CONCLUSION After 12 weeks of treatment, gaboxadol was found to be generally well-tolerated with a favorable safety profile. The efficacy as measured by the AS-adapted CGI-I scale warrants further studies. CLINICALTRIALSGOV IDENTIFIER NCT02996305. CLASSIFICATION OF EVIDENCE This study provides Class I evidence that, for individuals with AS, gaboxadol is generally safe and well-tolerated.
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Affiliation(s)
- Lynne M Bird
- From the University of California, San Diego (L.M.B.); Rady Children's Hospital (L.M.B.), San Diego, CA; Division of Developmental-Behavioral Pediatrics (C.O.-L.), Rush University Medical Center, Chicago, IL; Division of Genetics and Genomics (W.-H.T.), Boston Children's Hospital, Harvard Medical School, MA; Pediatric Neurology Unit (G.H.), Safra Children's Hospital, the Sheba Medical Center, Ramat Gan; The Sackler School of Medicine (G.H.), Tel Aviv University, Israel; Southwest Autism Research and Resource Center (R.D.M.), Phoenix, AZ; Ovid Therapeutics Inc. (A.R., M.J.D.); Neurogene (J.V.), New York, NY; Prometrika, LLC (C.H.), Cambridge, MA; Department of Molecular Biology (R.D.B.), Princeton University, NJ; Seaver Autism Center for Research and Treatment, Department of Psychiatry (A.K.), Icahn School of Medicine at Mount Sinai, New York, NY; and Angelman Syndrome Clinic, Department of Neurology (R.L.T.), Massachusetts General Hospital, Boston
| | - Cesar Ochoa-Lubinoff
- From the University of California, San Diego (L.M.B.); Rady Children's Hospital (L.M.B.), San Diego, CA; Division of Developmental-Behavioral Pediatrics (C.O.-L.), Rush University Medical Center, Chicago, IL; Division of Genetics and Genomics (W.-H.T.), Boston Children's Hospital, Harvard Medical School, MA; Pediatric Neurology Unit (G.H.), Safra Children's Hospital, the Sheba Medical Center, Ramat Gan; The Sackler School of Medicine (G.H.), Tel Aviv University, Israel; Southwest Autism Research and Resource Center (R.D.M.), Phoenix, AZ; Ovid Therapeutics Inc. (A.R., M.J.D.); Neurogene (J.V.), New York, NY; Prometrika, LLC (C.H.), Cambridge, MA; Department of Molecular Biology (R.D.B.), Princeton University, NJ; Seaver Autism Center for Research and Treatment, Department of Psychiatry (A.K.), Icahn School of Medicine at Mount Sinai, New York, NY; and Angelman Syndrome Clinic, Department of Neurology (R.L.T.), Massachusetts General Hospital, Boston
| | - Wen-Hann Tan
- From the University of California, San Diego (L.M.B.); Rady Children's Hospital (L.M.B.), San Diego, CA; Division of Developmental-Behavioral Pediatrics (C.O.-L.), Rush University Medical Center, Chicago, IL; Division of Genetics and Genomics (W.-H.T.), Boston Children's Hospital, Harvard Medical School, MA; Pediatric Neurology Unit (G.H.), Safra Children's Hospital, the Sheba Medical Center, Ramat Gan; The Sackler School of Medicine (G.H.), Tel Aviv University, Israel; Southwest Autism Research and Resource Center (R.D.M.), Phoenix, AZ; Ovid Therapeutics Inc. (A.R., M.J.D.); Neurogene (J.V.), New York, NY; Prometrika, LLC (C.H.), Cambridge, MA; Department of Molecular Biology (R.D.B.), Princeton University, NJ; Seaver Autism Center for Research and Treatment, Department of Psychiatry (A.K.), Icahn School of Medicine at Mount Sinai, New York, NY; and Angelman Syndrome Clinic, Department of Neurology (R.L.T.), Massachusetts General Hospital, Boston
| | - Gali Heimer
- From the University of California, San Diego (L.M.B.); Rady Children's Hospital (L.M.B.), San Diego, CA; Division of Developmental-Behavioral Pediatrics (C.O.-L.), Rush University Medical Center, Chicago, IL; Division of Genetics and Genomics (W.-H.T.), Boston Children's Hospital, Harvard Medical School, MA; Pediatric Neurology Unit (G.H.), Safra Children's Hospital, the Sheba Medical Center, Ramat Gan; The Sackler School of Medicine (G.H.), Tel Aviv University, Israel; Southwest Autism Research and Resource Center (R.D.M.), Phoenix, AZ; Ovid Therapeutics Inc. (A.R., M.J.D.); Neurogene (J.V.), New York, NY; Prometrika, LLC (C.H.), Cambridge, MA; Department of Molecular Biology (R.D.B.), Princeton University, NJ; Seaver Autism Center for Research and Treatment, Department of Psychiatry (A.K.), Icahn School of Medicine at Mount Sinai, New York, NY; and Angelman Syndrome Clinic, Department of Neurology (R.L.T.), Massachusetts General Hospital, Boston
| | - Raun D Melmed
- From the University of California, San Diego (L.M.B.); Rady Children's Hospital (L.M.B.), San Diego, CA; Division of Developmental-Behavioral Pediatrics (C.O.-L.), Rush University Medical Center, Chicago, IL; Division of Genetics and Genomics (W.-H.T.), Boston Children's Hospital, Harvard Medical School, MA; Pediatric Neurology Unit (G.H.), Safra Children's Hospital, the Sheba Medical Center, Ramat Gan; The Sackler School of Medicine (G.H.), Tel Aviv University, Israel; Southwest Autism Research and Resource Center (R.D.M.), Phoenix, AZ; Ovid Therapeutics Inc. (A.R., M.J.D.); Neurogene (J.V.), New York, NY; Prometrika, LLC (C.H.), Cambridge, MA; Department of Molecular Biology (R.D.B.), Princeton University, NJ; Seaver Autism Center for Research and Treatment, Department of Psychiatry (A.K.), Icahn School of Medicine at Mount Sinai, New York, NY; and Angelman Syndrome Clinic, Department of Neurology (R.L.T.), Massachusetts General Hospital, Boston
| | - Amit Rakhit
- From the University of California, San Diego (L.M.B.); Rady Children's Hospital (L.M.B.), San Diego, CA; Division of Developmental-Behavioral Pediatrics (C.O.-L.), Rush University Medical Center, Chicago, IL; Division of Genetics and Genomics (W.-H.T.), Boston Children's Hospital, Harvard Medical School, MA; Pediatric Neurology Unit (G.H.), Safra Children's Hospital, the Sheba Medical Center, Ramat Gan; The Sackler School of Medicine (G.H.), Tel Aviv University, Israel; Southwest Autism Research and Resource Center (R.D.M.), Phoenix, AZ; Ovid Therapeutics Inc. (A.R., M.J.D.); Neurogene (J.V.), New York, NY; Prometrika, LLC (C.H.), Cambridge, MA; Department of Molecular Biology (R.D.B.), Princeton University, NJ; Seaver Autism Center for Research and Treatment, Department of Psychiatry (A.K.), Icahn School of Medicine at Mount Sinai, New York, NY; and Angelman Syndrome Clinic, Department of Neurology (R.L.T.), Massachusetts General Hospital, Boston
| | - Jeannie Visootsak
- From the University of California, San Diego (L.M.B.); Rady Children's Hospital (L.M.B.), San Diego, CA; Division of Developmental-Behavioral Pediatrics (C.O.-L.), Rush University Medical Center, Chicago, IL; Division of Genetics and Genomics (W.-H.T.), Boston Children's Hospital, Harvard Medical School, MA; Pediatric Neurology Unit (G.H.), Safra Children's Hospital, the Sheba Medical Center, Ramat Gan; The Sackler School of Medicine (G.H.), Tel Aviv University, Israel; Southwest Autism Research and Resource Center (R.D.M.), Phoenix, AZ; Ovid Therapeutics Inc. (A.R., M.J.D.); Neurogene (J.V.), New York, NY; Prometrika, LLC (C.H.), Cambridge, MA; Department of Molecular Biology (R.D.B.), Princeton University, NJ; Seaver Autism Center for Research and Treatment, Department of Psychiatry (A.K.), Icahn School of Medicine at Mount Sinai, New York, NY; and Angelman Syndrome Clinic, Department of Neurology (R.L.T.), Massachusetts General Hospital, Boston
| | - Matthew J During
- From the University of California, San Diego (L.M.B.); Rady Children's Hospital (L.M.B.), San Diego, CA; Division of Developmental-Behavioral Pediatrics (C.O.-L.), Rush University Medical Center, Chicago, IL; Division of Genetics and Genomics (W.-H.T.), Boston Children's Hospital, Harvard Medical School, MA; Pediatric Neurology Unit (G.H.), Safra Children's Hospital, the Sheba Medical Center, Ramat Gan; The Sackler School of Medicine (G.H.), Tel Aviv University, Israel; Southwest Autism Research and Resource Center (R.D.M.), Phoenix, AZ; Ovid Therapeutics Inc. (A.R., M.J.D.); Neurogene (J.V.), New York, NY; Prometrika, LLC (C.H.), Cambridge, MA; Department of Molecular Biology (R.D.B.), Princeton University, NJ; Seaver Autism Center for Research and Treatment, Department of Psychiatry (A.K.), Icahn School of Medicine at Mount Sinai, New York, NY; and Angelman Syndrome Clinic, Department of Neurology (R.L.T.), Massachusetts General Hospital, Boston
| | - Christina Holcroft
- From the University of California, San Diego (L.M.B.); Rady Children's Hospital (L.M.B.), San Diego, CA; Division of Developmental-Behavioral Pediatrics (C.O.-L.), Rush University Medical Center, Chicago, IL; Division of Genetics and Genomics (W.-H.T.), Boston Children's Hospital, Harvard Medical School, MA; Pediatric Neurology Unit (G.H.), Safra Children's Hospital, the Sheba Medical Center, Ramat Gan; The Sackler School of Medicine (G.H.), Tel Aviv University, Israel; Southwest Autism Research and Resource Center (R.D.M.), Phoenix, AZ; Ovid Therapeutics Inc. (A.R., M.J.D.); Neurogene (J.V.), New York, NY; Prometrika, LLC (C.H.), Cambridge, MA; Department of Molecular Biology (R.D.B.), Princeton University, NJ; Seaver Autism Center for Research and Treatment, Department of Psychiatry (A.K.), Icahn School of Medicine at Mount Sinai, New York, NY; and Angelman Syndrome Clinic, Department of Neurology (R.L.T.), Massachusetts General Hospital, Boston
| | - Rebecca D Burdine
- From the University of California, San Diego (L.M.B.); Rady Children's Hospital (L.M.B.), San Diego, CA; Division of Developmental-Behavioral Pediatrics (C.O.-L.), Rush University Medical Center, Chicago, IL; Division of Genetics and Genomics (W.-H.T.), Boston Children's Hospital, Harvard Medical School, MA; Pediatric Neurology Unit (G.H.), Safra Children's Hospital, the Sheba Medical Center, Ramat Gan; The Sackler School of Medicine (G.H.), Tel Aviv University, Israel; Southwest Autism Research and Resource Center (R.D.M.), Phoenix, AZ; Ovid Therapeutics Inc. (A.R., M.J.D.); Neurogene (J.V.), New York, NY; Prometrika, LLC (C.H.), Cambridge, MA; Department of Molecular Biology (R.D.B.), Princeton University, NJ; Seaver Autism Center for Research and Treatment, Department of Psychiatry (A.K.), Icahn School of Medicine at Mount Sinai, New York, NY; and Angelman Syndrome Clinic, Department of Neurology (R.L.T.), Massachusetts General Hospital, Boston
| | - Alexander Kolevzon
- From the University of California, San Diego (L.M.B.); Rady Children's Hospital (L.M.B.), San Diego, CA; Division of Developmental-Behavioral Pediatrics (C.O.-L.), Rush University Medical Center, Chicago, IL; Division of Genetics and Genomics (W.-H.T.), Boston Children's Hospital, Harvard Medical School, MA; Pediatric Neurology Unit (G.H.), Safra Children's Hospital, the Sheba Medical Center, Ramat Gan; The Sackler School of Medicine (G.H.), Tel Aviv University, Israel; Southwest Autism Research and Resource Center (R.D.M.), Phoenix, AZ; Ovid Therapeutics Inc. (A.R., M.J.D.); Neurogene (J.V.), New York, NY; Prometrika, LLC (C.H.), Cambridge, MA; Department of Molecular Biology (R.D.B.), Princeton University, NJ; Seaver Autism Center for Research and Treatment, Department of Psychiatry (A.K.), Icahn School of Medicine at Mount Sinai, New York, NY; and Angelman Syndrome Clinic, Department of Neurology (R.L.T.), Massachusetts General Hospital, Boston.
| | - Ronald L Thibert
- From the University of California, San Diego (L.M.B.); Rady Children's Hospital (L.M.B.), San Diego, CA; Division of Developmental-Behavioral Pediatrics (C.O.-L.), Rush University Medical Center, Chicago, IL; Division of Genetics and Genomics (W.-H.T.), Boston Children's Hospital, Harvard Medical School, MA; Pediatric Neurology Unit (G.H.), Safra Children's Hospital, the Sheba Medical Center, Ramat Gan; The Sackler School of Medicine (G.H.), Tel Aviv University, Israel; Southwest Autism Research and Resource Center (R.D.M.), Phoenix, AZ; Ovid Therapeutics Inc. (A.R., M.J.D.); Neurogene (J.V.), New York, NY; Prometrika, LLC (C.H.), Cambridge, MA; Department of Molecular Biology (R.D.B.), Princeton University, NJ; Seaver Autism Center for Research and Treatment, Department of Psychiatry (A.K.), Icahn School of Medicine at Mount Sinai, New York, NY; and Angelman Syndrome Clinic, Department of Neurology (R.L.T.), Massachusetts General Hospital, Boston
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Gorski K, Spoljaric A, Nyman TA, Kaila K, Battersby BJ, Lehesjoki AE. Quantitative Changes in the Mitochondrial Proteome of Cerebellar Synaptosomes From Preclinical Cystatin B-Deficient Mice. Front Mol Neurosci 2020; 13:570640. [PMID: 33281550 PMCID: PMC7691638 DOI: 10.3389/fnmol.2020.570640] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 10/21/2020] [Indexed: 12/04/2022] Open
Abstract
Progressive myoclonus epilepsy of Unverricht-Lundborg type (EPM1) is a neurodegenerative disorder caused by loss-of-function mutations in the cystatin B (CSTB) gene. Progression of the clinical symptoms in EPM1 patients, including stimulus-sensitive myoclonus, tonic-clonic seizures, and ataxia, are well described. However, the cellular dysfunction during the presymptomatic phase that precedes the disease onset is not understood. CSTB deficiency leads to alterations in GABAergic signaling, and causes early neuroinflammation followed by progressive neurodegeneration in brains of a mouse model, manifesting as progressive myoclonus and ataxia. Here, we report the first proteome atlas from cerebellar synaptosomes of presymptomatic Cstb-deficient mice, and propose that early mitochondrial dysfunction is important to the pathogenesis of altered synaptic function in EPM1. A decreased sodium- and chloride dependent GABA transporter 1 (GAT-1) abundance was noted in synaptosomes with CSTB deficiency, but no functional difference was seen between the two genotypes in electrophysiological experiments with pharmacological block of GAT-1. Collectively, our findings provide novel insights into the early onset and pathogenesis of CSTB deficiency, and reveal greater complexity to the molecular pathogenesis of EPM1.
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Affiliation(s)
- Katarin Gorski
- Folkhälsan Research Center, Helsinki, Finland.,Department of Medical and Clinical Genetics, Medicum, University of Helsinki, Helsinki, Finland
| | - Albert Spoljaric
- Molecular and Integrative Biosciences, and Neuroscience Center (HiLIFE), Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | - Tuula A Nyman
- Institute of Clinical Medicine, University of Oslo and Oslo University Hospital, Oslo, Norway
| | - Kai Kaila
- Molecular and Integrative Biosciences, and Neuroscience Center (HiLIFE), Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | | | - Anna-Elina Lehesjoki
- Folkhälsan Research Center, Helsinki, Finland.,Department of Medical and Clinical Genetics, Medicum, University of Helsinki, Helsinki, Finland
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35
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Effect of diverse recoding of granule cells on optokinetic response in a cerebellar ring network with synaptic plasticity. Neural Netw 2020; 134:173-204. [PMID: 33316723 DOI: 10.1016/j.neunet.2020.11.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 11/12/2020] [Accepted: 11/24/2020] [Indexed: 11/21/2022]
Abstract
We consider a cerebellar ring network for the optokinetic response (OKR), and investigate the effect of diverse recoding of granule (GR) cells on OKR by varying the connection probability pc from Golgi to GR cells. For an optimal value of pc∗(=0.06), individual GR cells exhibit diverse spiking patterns which are in-phase, anti-phase, or complex out-of-phase with respect to their population-averaged firing activity. Then, these diversely-recoded signals via parallel fibers (PFs) from GR cells are effectively depressed by the error-teaching signals via climbing fibers from the inferior olive which are also in-phase ones. Synaptic weights at in-phase PF-Purkinje cell (PC) synapses of active GR cells are strongly depressed via strong long-term depression (LTD), while those at anti-phase and complex out-of-phase PF-PC synapses are weakly depressed through weak LTD. This kind of "effective" depression (i.e., strong/weak LTD) at the PF-PC synapses causes a big modulation in firings of PCs, which then exert effective inhibitory coordination on the vestibular nucleus (VN) neuron (which evokes OKR). For the firing of the VN neuron, the learning gain degree Lg, corresponding to the modulation gain ratio, increases with increasing the learning cycle, and it saturates at about the 300th cycle. By varying pc from pc∗, we find that a plot of saturated learning gain degree Lg∗ versus pc forms a bell-shaped curve with a peak at pc∗ (where the diversity degree in spiking patterns of GR cells is also maximum). Consequently, the more diverse in recoding of GR cells, the more effective in motor learning for the OKR adaptation.
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36
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McCauley JP, Petroccione MA, D'Brant LY, Todd GC, Affinnih N, Wisnoski JJ, Zahid S, Shree S, Sousa AA, De Guzman RM, Migliore R, Brazhe A, Leapman RD, Khmaladze A, Semyanov A, Zuloaga DG, Migliore M, Scimemi A. Circadian Modulation of Neurons and Astrocytes Controls Synaptic Plasticity in Hippocampal Area CA1. Cell Rep 2020; 33:108255. [PMID: 33053337 PMCID: PMC7700820 DOI: 10.1016/j.celrep.2020.108255] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 08/21/2020] [Accepted: 09/18/2020] [Indexed: 12/18/2022] Open
Abstract
Most animal species operate according to a 24-h period set by the suprachiasmatic nucleus (SCN) of the hypothalamus. The rhythmic activity of the SCN modulates hippocampal-dependent memory, but the molecular and cellular mechanisms that account for this effect remain largely unknown. Here, we identify cell-type-specific structural and functional changes that occur with circadian rhythmicity in neurons and astrocytes in hippocampal area CA1. Pyramidal neurons change the surface expression of NMDA receptors. Astrocytes change their proximity to synapses. Together, these phenomena alter glutamate clearance, receptor activation, and integration of temporally clustered excitatory synaptic inputs, ultimately shaping hippocampal-dependent learning in vivo. We identify corticosterone as a key contributor to changes in synaptic strength. These findings highlight important mechanisms through which neurons and astrocytes modify the molecular composition and structure of the synaptic environment, contribute to the local storage of information in the hippocampus, and alter the temporal dynamics of cognitive processing.
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Affiliation(s)
- John P McCauley
- Department of Biology, SUNY Albany, 1400 Washington Avenue, Albany, NY 12222, USA
| | | | - Lianna Y D'Brant
- Department of Biology, SUNY Albany, 1400 Washington Avenue, Albany, NY 12222, USA; Department of Physics, SUNY Albany, 1400 Washington Avenue, Albany, NY 12222, USA
| | - Gabrielle C Todd
- Department of Biology, SUNY Albany, 1400 Washington Avenue, Albany, NY 12222, USA
| | - Nurat Affinnih
- Department of Biology, SUNY Albany, 1400 Washington Avenue, Albany, NY 12222, USA
| | - Justin J Wisnoski
- Department of Biology, SUNY Albany, 1400 Washington Avenue, Albany, NY 12222, USA
| | - Shergil Zahid
- Department of Biology, SUNY Albany, 1400 Washington Avenue, Albany, NY 12222, USA
| | - Swasti Shree
- Department of Biology, SUNY Albany, 1400 Washington Avenue, Albany, NY 12222, USA; Bethlehem Central High School, 700 Delaware Avenue, Delmar, NY 12054, USA
| | - Alioscka A Sousa
- Federal University of São Paulo, Department of Biochemistry, 100 Rua Tres de Maio, São Paulo 04044-020, Brazil; National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA
| | - Rose M De Guzman
- Department of Psychology, SUNY Albany, 1400 Washington Avenue, Albany, NY 12222, USA
| | - Rosanna Migliore
- Institute of Biophysics, National Research Council, 153 Via Ugo La Malfa, Palermo 90146, Italy
| | - Alexey Brazhe
- Department of Biophysics, Lomonosov Moscow State University, Leninskie Gory 1/12, Moscow 119234, Russia; Department of Molecular Neurobiology, Institute of Bioorganic Chemistry, Ulitsa Miklukho-Maklaya 16/10, Moscow 117997, Russia
| | - Richard D Leapman
- National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA
| | - Alexander Khmaladze
- Department of Physics, SUNY Albany, 1400 Washington Avenue, Albany, NY 12222, USA
| | - Alexey Semyanov
- Department of Molecular Neurobiology, Institute of Bioorganic Chemistry, Ulitsa Miklukho-Maklaya 16/10, Moscow 117997, Russia; Sechenov First Moscow State Medical University, Bolshaya Pirogovskaya Ulitsa 19с1, Moscow 119146, Russia
| | - Damian G Zuloaga
- Department of Psychology, SUNY Albany, 1400 Washington Avenue, Albany, NY 12222, USA
| | - Michele Migliore
- Institute of Biophysics, National Research Council, 153 Via Ugo La Malfa, Palermo 90146, Italy
| | - Annalisa Scimemi
- Department of Biology, SUNY Albany, 1400 Washington Avenue, Albany, NY 12222, USA.
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37
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Serratto GM, Pizzi E, Murru L, Mazzoleni S, Pelucchi S, Marcello E, Mazzanti M, Passafaro M, Bassani S. The Epilepsy-Related Protein PCDH19 Regulates Tonic Inhibition, GABA AR Kinetics, and the Intrinsic Excitability of Hippocampal Neurons. Mol Neurobiol 2020; 57:5336-5351. [PMID: 32880860 PMCID: PMC7541378 DOI: 10.1007/s12035-020-02099-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 08/25/2020] [Indexed: 12/19/2022]
Abstract
PCDH19 encodes for protocadherin-19 (PCDH19), a cell-adhesion molecule of the cadherin superfamily preferentially expressed in the brain. PCDH19 mutations cause a neurodevelopmental syndrome named epileptic encephalopathy, early infantile, 9 (EIEE9) characterized by seizures associated with cognitive and behavioral deficits. We recently reported that PCDH19 binds the alpha subunits of GABAA receptors (GABAARs), modulating their surface availability and miniature inhibitory postsynaptic currents (mIPSCs). Here, we investigated whether PCDH19 regulatory function on GABAARs extends to the extrasynaptic receptor pool that mediates tonic current. In fact, the latter shapes neuronal excitability and network properties at the base of information processing. By combining patch-clamp recordings in whole-cell and cell-attached configurations, we provided a functional characterization of primary hippocampal neurons from embryonic rats of either sex expressing a specific PCDH19 short hairpin (sh)RNA. We first demonstrated that PCDH19 downregulation reduces GABAAR-mediated tonic current, evaluated by current shift and baseline noise analysis. Next, by single-channel recordings, we showed that PCDH19 regulates GABAARs kinetics without altering their conductance. In particular, GABAARs of shRNA-expressing neurons preferentially exhibit brief openings at the expense of long ones, thus displaying a flickering behavior. Finally, we showed that PCDH19 downregulation reduces the rheobase and increases the frequency of action potential firing, thus indicating neuronal hyperexcitability. These findings establish PCDH19 as a critical determinant of GABAAR-mediated tonic transmission and GABAARs gating, and provide the first mechanistic insights into PCDH19-related hyperexcitability and comorbidities.
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Affiliation(s)
| | - Erika Pizzi
- Department of Bioscience, University of Milan, 20133, Milan, Italy
| | - Luca Murru
- Institute of Neuroscience, CNR, 20129, Milan, Italy.,NeuroMI Milan Center for Neuroscience, University of Milano-Bicocca, 20126, Milan, Italy
| | - Sara Mazzoleni
- Institute of Neuroscience, CNR, 20129, Milan, Italy.,Department of Medical Biotechnology and Translational Medicine, University of Milan, 20129, Milan, Italy
| | - Silvia Pelucchi
- Department of Pharmacological and Biomolecular Sciences, University of Milan, 20133, Milan, Italy
| | - Elena Marcello
- Department of Pharmacological and Biomolecular Sciences, University of Milan, 20133, Milan, Italy
| | - Michele Mazzanti
- Department of Bioscience, University of Milan, 20133, Milan, Italy
| | - Maria Passafaro
- Institute of Neuroscience, CNR, 20129, Milan, Italy.,NeuroMI Milan Center for Neuroscience, University of Milano-Bicocca, 20126, Milan, Italy
| | - Silvia Bassani
- Institute of Neuroscience, CNR, 20129, Milan, Italy. .,NeuroMI Milan Center for Neuroscience, University of Milano-Bicocca, 20126, Milan, Italy.
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38
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Marín M, Sáez-Lara MJ, Ros E, Garrido JA. Optimization of Efficient Neuron Models With Realistic Firing Dynamics. The Case of the Cerebellar Granule Cell. Front Cell Neurosci 2020; 14:161. [PMID: 32765220 PMCID: PMC7381211 DOI: 10.3389/fncel.2020.00161] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 05/13/2020] [Indexed: 11/17/2022] Open
Abstract
Biologically relevant large-scale computational models currently represent one of the main methods in neuroscience for studying information processing primitives of brain areas. However, biologically realistic neuron models tend to be computationally heavy and thus prevent these models from being part of brain-area models including thousands or even millions of neurons. The cerebellar input layer represents a canonical example of large scale networks. In particular, the cerebellar granule cells, the most numerous cells in the whole mammalian brain, have been proposed as playing a pivotal role in the creation of somato-sensorial information representations. Enhanced burst frequency (spiking resonance) in the granule cells has been proposed as facilitating the input signal transmission at the theta-frequency band (4–12 Hz), but the functional role of this cell feature in the operation of the granular layer remains largely unclear. This study aims to develop a methodological pipeline for creating neuron models that maintain biological realism and computational efficiency whilst capturing essential aspects of single-neuron processing. Therefore, we selected a light computational neuron model template (the adaptive-exponential integrate-and-fire model), whose parameters were progressively refined using an automatic parameter tuning with evolutionary algorithms (EAs). The resulting point-neuron models are suitable for reproducing the main firing properties of a realistic granule cell from electrophysiological measurements, including the spiking resonance at the theta-frequency band, repetitive firing according to a specified intensity-frequency (I-F) curve and delayed firing under current-pulse stimulation. Interestingly, the proposed model also reproduced some other emergent properties (namely, silent at rest, rheobase and negligible adaptation under depolarizing currents) even though these properties were not set in the EA as a target in the fitness function (FF), proving that these features are compatible even in computationally simple models. The proposed methodology represents a valuable tool for adjusting AdEx models according to a FF defined in the spiking regime and based on biological data. These models are appropriate for future research of the functional implication of bursting resonance at the theta band in large-scale granular layer network models.
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Affiliation(s)
- Milagros Marín
- Department of Computer Architecture and Technology-CITIC, University of Granada, Granada, Spain.,Department of Biochemistry and Molecular Biology I, University of Granada, Granada, Spain
| | - María José Sáez-Lara
- Department of Biochemistry and Molecular Biology I, University of Granada, Granada, Spain
| | - Eduardo Ros
- Department of Computer Architecture and Technology-CITIC, University of Granada, Granada, Spain
| | - Jesús A Garrido
- Department of Computer Architecture and Technology-CITIC, University of Granada, Granada, Spain
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39
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Netsyk O, Hammoud H, Korol SV, Jin Z, Tafreshiha AS, Birnir B. Tonic
GABA
‐activated synaptic and extrasynaptic currents in dentate gyrus granule cells and
CA3
pyramidal neurons along the mouse hippocampal dorsoventral axis. Hippocampus 2020; 30:1146-1157. [DOI: 10.1002/hipo.23245] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 05/24/2020] [Accepted: 05/26/2020] [Indexed: 12/12/2022]
Affiliation(s)
- Olga Netsyk
- Department of Medical Cell Biology Uppsala University Uppsala Sweden
| | - Hayma Hammoud
- Department of Medical Cell Biology Uppsala University Uppsala Sweden
| | - Sergiy V. Korol
- Department of Medical Cell Biology Uppsala University Uppsala Sweden
| | - Zhe Jin
- Department of Medical Cell Biology Uppsala University Uppsala Sweden
| | | | - Bryndis Birnir
- Department of Medical Cell Biology Uppsala University Uppsala Sweden
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40
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Masoli S, Tognolina M, Laforenza U, Moccia F, D'Angelo E. Parameter tuning differentiates granule cell subtypes enriching transmission properties at the cerebellum input stage. Commun Biol 2020; 3:222. [PMID: 32385389 PMCID: PMC7210112 DOI: 10.1038/s42003-020-0953-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Accepted: 04/13/2020] [Indexed: 02/06/2023] Open
Abstract
The cerebellar granule cells (GrCs) are classically described as a homogeneous neuronal population discharging regularly without adaptation. We show that GrCs in fact generate diverse response patterns to current injection and synaptic activation, ranging from adaptation to acceleration of firing. Adaptation was predicted by parameter optimization in detailed computational models based on available knowledge on GrC ionic channels. The models also predicted that acceleration required additional mechanisms. We found that yet unrecognized TRPM4 currents specifically accounted for firing acceleration and that adapting GrCs outperformed accelerating GrCs in transmitting high-frequency mossy fiber (MF) bursts over a background discharge. This implied that GrC subtypes identified by their electroresponsiveness corresponded to specific neurotransmitter release probability values. Simulations showed that fine-tuning of pre- and post-synaptic parameters generated effective MF-GrC transmission channels, which could enrich the processing of input spike patterns and enhance spatio-temporal recoding at the cerebellar input stage.
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Affiliation(s)
- Stefano Masoli
- Department of Brain and Behavioral Sciences, University of Pavia, Via Forlanini 6, 27100, Pavia, Italy
| | - Marialuisa Tognolina
- Department of Brain and Behavioral Sciences, University of Pavia, Via Forlanini 6, 27100, Pavia, Italy
| | - Umberto Laforenza
- Department of Molecular Medicine, University of Pavia, Via Forlanini 6, 27100, Pavia, Italy
| | - Francesco Moccia
- Department of Biology and Biotechnology, University of Pavia, Via Forlanini 6, 27100, Pavia, Italy
| | - Egidio D'Angelo
- Department of Brain and Behavioral Sciences, University of Pavia, Via Forlanini 6, 27100, Pavia, Italy. .,Brain Connectivity Center, IRCCS Mondino Foundation, Via Mondino 2, 27100, Pavia, Italy.
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41
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Tonic GABA A Conductance Favors Spike-Timing-Dependent over Theta-Burst-Induced Long-Term Potentiation in the Hippocampus. J Neurosci 2020; 40:4266-4276. [PMID: 32327534 DOI: 10.1523/jneurosci.2118-19.2020] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Revised: 03/21/2020] [Accepted: 04/15/2020] [Indexed: 11/21/2022] Open
Abstract
Synaptic plasticity is triggered by different patterns of network activity. Here, we investigated how LTP in CA3-CA1 synapses induced by different stimulation patterns is affected by tonic GABAA conductances in rat hippocampal slices. Spike-timing-dependent LTP was induced by pairing Schaffer collateral stimulation with antidromic stimulation of CA1 pyramidal neurons. Theta-burst-induced LTP was induced by theta-burst stimulation of Schaffer collaterals. We mimicked increased tonic GABAA conductance by bath application of 30 μm GABA. Surprisingly, tonic GABAA conductance selectively suppressed theta-burst-induced LTP but not spike-timing-dependent LTP. We combined whole-cell patch-clamp electrophysiology, two-photon Ca2+ imaging, glutamate uncaging, and mathematical modeling to dissect the mechanisms underlying these differential effects of tonic GABAA conductance. We found that Ca2+ transients during pairing of an action potential with an EPSP were less sensitive to tonic GABAA conductance-induced shunting inhibition than Ca2+ transients induced by EPSP burst. Our results may explain how different forms of memory are affected by increasing tonic GABAA conductances under physiological or pathologic conditions, as well as under the influence of substances that target extrasynaptic GABAA receptors (e.g., neurosteroids, sedatives, antiepileptic drugs, and alcohol).SIGNIFICANCE STATEMENT Brain activity is associated with neuronal firing and synaptic signaling among neurons. Synaptic plasticity represents a mechanism for learning and memory. However, some neurotransmitters that escape the synaptic cleft or are released by astrocytes can target extrasynaptic receptors. Extrasynaptic GABAA receptors mediate tonic conductances that reduce the excitability of neurons by shunting. This results in the decreased ability for neurons to fire action potentials, but when action potentials are successfully triggered, tonic conductances are unable to reduce them significantly. As such, tonic GABAA conductances have minimal effects on spike-timing-dependent synaptic plasticity while strongly attenuating the plasticity evoked by EPSP bursts. Our findings shed light on how changes in tonic conductances can selectively affect different forms of learning and memory.
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42
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Falck J, Bruns C, Hoffmann-Conaway S, Straub I, Plautz EJ, Orlando M, Munawar H, Rivalan M, Winter Y, Izsvák Z, Schmitz D, Hamra FK, Hallermann S, Garner CC, Ackermann F. Loss of Piccolo Function in Rats Induces Cerebellar Network Dysfunction and Pontocerebellar Hypoplasia Type 3-like Phenotypes. J Neurosci 2020; 40:2943-2959. [PMID: 32122952 PMCID: PMC7117892 DOI: 10.1523/jneurosci.2316-19.2020] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 02/10/2020] [Accepted: 02/13/2020] [Indexed: 12/16/2022] Open
Abstract
Piccolo, a presynaptic active zone protein, is best known for its role in the regulated assembly and function of vertebrate synapses. Genetic studies suggest a further link to several psychiatric disorders as well as Pontocerebellar Hypoplasia type 3 (PCH3). We have characterized recently generated Piccolo KO (Pclogt/gt ) rats. Analysis of rats of both sexes revealed a dramatic reduction in brain size compared with WT (Pclowt/wt ) animals, attributed to a decrease in the size of the cerebral cortical, cerebellar, and pontine regions. Analysis of the cerebellum and brainstem revealed a reduced granule cell layer and a reduction in size of pontine nuclei. Moreover, the maturation of mossy fiber afferents from pontine neurons and the expression of the α6 GABAA receptor subunit at the mossy fiber-granule cell synapse are perturbed, as well as the innervation of Purkinje cells by cerebellar climbing fibers. Ultrastructural and functional studies revealed a reduced size of mossy fiber boutons, with fewer synaptic vesicles and altered synaptic transmission. These data imply that Piccolo is required for the normal development, maturation, and function of neuronal networks formed between the brainstem and cerebellum. Consistently, behavioral studies demonstrated that adult Pclogt/gt rats display impaired motor coordination, despite adequate performance in tasks that reflect muscle strength and locomotion. Together, these data suggest that loss of Piccolo function in patients with PCH3 could be involved in many of the observed anatomical and behavioral symptoms, and that the further analysis of these animals could provide fundamental mechanistic insights into this devastating disorder.SIGNIFICANCE STATEMENT Pontocerebellar Hypoplasia Type 3 is a devastating developmental disorder associated with severe developmental delay, progressive microcephaly with brachycephaly, optic atrophy, seizures, and hypertonia with hyperreflexia. Recent genetic studies have identified non-sense mutations in the coding region of the PCLO gene, suggesting a functional link between this disorder and the presynaptic active zone. Our analysis of Piccolo KO rats supports this hypothesis, formally demonstrating that anatomical and behavioral phenotypes seen in patients with Pontocerebellar Hypoplasia Type 3 are also exhibited by these Piccolo deficient animals.
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Affiliation(s)
- Joanne Falck
- German Center for Neurodegenerative Diseases, Charité Medical University, 10117 Berlin, Germany
| | - Christine Bruns
- German Center for Neurodegenerative Diseases, Charité Medical University, 10117 Berlin, Germany
| | - Sheila Hoffmann-Conaway
- German Center for Neurodegenerative Diseases, Charité Medical University, 10117 Berlin, Germany
| | - Isabelle Straub
- Carl-Ludwig Institute for Physiology, 04103 Leipzig, Germany
| | - Erik J Plautz
- Department of Neurology and Neurotherapeutics, University of Texas Southwestern, Dallas, Texas 75390
| | - Marta Orlando
- Charité Medical University Berlin and Berlin Institute of Health, NeuroCure Cluster of Excellence, 10117 Berlin, Germany
| | - Humaira Munawar
- Department of Biology, Humboldt University, 10099 Berlin, Germany
| | - Marion Rivalan
- Charité Medical University Berlin and Berlin Institute of Health, NeuroCure Cluster of Excellence, 10117 Berlin, Germany
- Department of Biology, Humboldt University, 10099 Berlin, Germany
| | - York Winter
- Charité Medical University Berlin and Berlin Institute of Health, NeuroCure Cluster of Excellence, 10117 Berlin, Germany
- Department of Biology, Humboldt University, 10099 Berlin, Germany
| | - Zsuzsanna Izsvák
- Max Delbrück Center for Molecular Medicine in the Helmholtz Society, 13125 Berlin, Germany, and
| | - Dietmar Schmitz
- Charité Medical University Berlin and Berlin Institute of Health, NeuroCure Cluster of Excellence, 10117 Berlin, Germany
| | - F Kent Hamra
- Department of Obstetrics and Gynecology, Cecil H. and Ida Green Center for Reproductive Biology Sciences, University of Texas Southwestern, Dallas, Texas 75390
| | | | - Craig Curtis Garner
- German Center for Neurodegenerative Diseases, Charité Medical University, 10117 Berlin, Germany
| | - Frauke Ackermann
- German Center for Neurodegenerative Diseases, Charité Medical University, 10117 Berlin, Germany,
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43
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Acetylcholine Modulates Cerebellar Granule Cell Spiking by Regulating the Balance of Synaptic Excitation and Inhibition. J Neurosci 2020; 40:2882-2894. [PMID: 32111698 DOI: 10.1523/jneurosci.2148-19.2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 02/03/2020] [Accepted: 02/20/2020] [Indexed: 12/20/2022] Open
Abstract
Sensorimotor integration in the cerebellum is essential for refining motor output, and the first stage of this processing occurs in the granule cell layer. Recent evidence suggests that granule cell layer synaptic integration can be contextually modified, although the circuit mechanisms that could mediate such modulation remain largely unknown. Here we investigate the role of ACh in regulating granule cell layer synaptic integration in male rats and mice of both sexes. We find that Golgi cells, interneurons that provide the sole source of inhibition to the granule cell layer, express both nicotinic and muscarinic cholinergic receptors. While acute ACh application can modestly depolarize some Golgi cells, the net effect of longer, optogenetically induced ACh release is to strongly hyperpolarize Golgi cells. Golgi cell hyperpolarization by ACh leads to a significant reduction in both tonic and evoked granule cell synaptic inhibition. ACh also reduces glutamate release from mossy fibers by acting on presynaptic muscarinic receptors. Surprisingly, despite these consistent effects on Golgi cells and mossy fibers, ACh can either increase or decrease the spike probability of granule cells as measured by noninvasive cell-attached recordings. By constructing an integrate-and-fire model of granule cell layer population activity, we find that the direction of spike rate modulation can be accounted for predominately by the initial balance of excitation and inhibition onto individual granule cells. Together, these experiments demonstrate that ACh can modulate population-level granule cell responses by altering the ratios of excitation and inhibition at the first stage of cerebellar processing.SIGNIFICANCE STATEMENT The cerebellum plays a key role in motor control and motor learning. While it is known that behavioral context can modify motor learning, the circuit basis of such modulation has remained unclear. Here we find that a key neuromodulator, ACh, can alter the balance of excitation and inhibition at the first stage of cerebellar processing. These results suggest that ACh could play a key role in altering cerebellar learning by modifying how sensorimotor input is represented at the input layer of the cerebellum.
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44
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Photosensitive inhibition of the GABA system in vitro. Sci Rep 2020; 10:3133. [PMID: 32081949 PMCID: PMC7035376 DOI: 10.1038/s41598-020-59915-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 01/27/2020] [Indexed: 11/19/2022] Open
Abstract
In the central nervous system (CNS), γ–aminobutyric acid A (GABAA) receptors mediate two types of inhibitory effects. Phasic inhibition involves the activation of synaptic GABAA receptors, and tonic inhibition is mediated by extrasynaptic GABAA receptors. GABAA receptors are important regulators of neuronal activity and are involved in a range of neurological disorders. In this study, we conducted sIPSCs recordings on hippocampal CA1 pyramidal neurons in WT SD rats and found that exposure to blue light could specifically block the tonic inhibition and sIPSCs, and regulate neuronal activity. These observations indicate the existence of a non-opsin photosensitive pathway that regulates the GABA inhibitory system in the CNS.
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45
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Hoshino O, Kameno R, Watanabe K. Reducing variability in motor cortex activity at a resting state by extracellular GABA for reliable perceptual decision-making. J Comput Neurosci 2019; 47:191-204. [PMID: 31720999 DOI: 10.1007/s10827-019-00732-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 07/31/2019] [Accepted: 10/01/2019] [Indexed: 11/28/2022]
Abstract
Interaction between sensory and motor cortices is crucial for perceptual decision-making, in which intracortical inhibition might have an important role. We simulated a neural network model consisting of a sensory network (NS) and a motor network (NM) to elucidate the significance of their interaction in perceptual decision-making in association with the level of GABA in extracellular space: extracellular GABA concentration. Extracellular GABA molecules acted on extrasynaptic receptors embedded in membranes of pyramidal cells and suppressed them. A reduction in extracellular GABA concentration either in NS or NM increased the rate of errors in perceptual decision-making, for which an increase in ongoing-spontaneous fluctuations in subthreshold neuronal activity in NM prior to sensory stimulation was responsible. Feedback (NM-to-NS) signaling enhanced selective neuronal responses in NS, which in turn increased stimulus-evoked neuronal activity in NM. We suggest that GABA in extracellular space contributes to reducing variability in motor cortex activity at a resting state and thereby the motor cortex can respond correctly to a subsequent sensory stimulus. Feedback signaling from the motor cortex improves the selective responsiveness of the sensory cortex, which ensures the fidelity of information transmission to the motor cortex, leading to reliable perceptual decision-making.
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Affiliation(s)
- Osamu Hoshino
- Department of Intelligent Systems Engineering, Ibaraki University, 4-12-1 Nakanarusawa, Hitachi, Ibaraki, 316-8511, Japan. .,Southern Tohoku Research Institute for Neuroscience, Southern Tohoku General Hospital, 7-115, Yatsuyamada, Koriyama, Fukushima, 963-8563, Japan.
| | - Rikiya Kameno
- Southern Tohoku Research Institute for Neuroscience, Southern Tohoku General Hospital, 7-115, Yatsuyamada, Koriyama, Fukushima, 963-8563, Japan
| | - Kazuo Watanabe
- Southern Tohoku Research Institute for Neuroscience, Southern Tohoku General Hospital, 7-115, Yatsuyamada, Koriyama, Fukushima, 963-8563, Japan
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46
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Mechanisms of GABA B receptor enhancement of extrasynaptic GABA A receptor currents in cerebellar granule cells. Sci Rep 2019; 9:16683. [PMID: 31723152 PMCID: PMC6853962 DOI: 10.1038/s41598-019-53087-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 10/26/2019] [Indexed: 12/31/2022] Open
Abstract
Many neurons, including cerebellar granule cells, exhibit a tonic GABA current mediated by extrasynaptic GABAA receptors. This current is a critical regulator of firing and the target of many clinically relevant compounds. Using a combination of patch clamp electrophysiology and photolytic uncaging of RuBi-GABA we show that GABAB receptors are tonically active and enhance extrasynaptic GABAA receptor currents in cerebellar granule cells. This enhancement is not associated with meaningful changes in GABAA receptor potency, mean channel open-time, open probability, or single-channel current. However, there was a significant (~40%) decrease in the number of channels participating in the GABA uncaging current and an increase in receptor desensitization. Furthermore, we find that adenylate cyclase, PKA, CaMKII, and release of Ca2+ from intracellular stores are necessary for modulation of GABAA receptors. Overall, this work reveals crosstalk between postsynaptic GABAA and GABAB receptors and identifies the signaling pathways and mechanisms involved.
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47
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Prestori F, Mapelli L, D'Angelo E. Diverse Neuron Properties and Complex Network Dynamics in the Cerebellar Cortical Inhibitory Circuit. Front Mol Neurosci 2019; 12:267. [PMID: 31787879 PMCID: PMC6854908 DOI: 10.3389/fnmol.2019.00267] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 10/17/2019] [Indexed: 12/12/2022] Open
Abstract
Neuronal inhibition can be defined as a spatiotemporal restriction or suppression of local microcircuit activity. The importance of inhibition relies in its fundamental role in shaping signal processing in single neurons and neuronal circuits. In this context, the activity of inhibitory interneurons proved the key to endow networks with complex computational and dynamic properties. In the last 50 years, the prevailing view on the functional role of cerebellar cortical inhibitory circuits was that excitatory and inhibitory inputs sum spatially and temporally in order to determine the motor output through Purkinje cells (PCs). Consequently, cerebellar inhibition has traditionally been conceived in terms of restricting or blocking excitation. This assumption has been challenged, in particular in the cerebellar cortex where all neurons except granule cells (and unipolar brush cells in specific lobules) are inhibitory and fire spontaneously at high rates. Recently, a combination of electrophysiological recordings in vitro and in vivo, imaging, optogenetics and computational modeling, has revealed that inhibitory interneurons play a much more complex role in regulating cerebellar microcircuit functions: inhibition shapes neuronal response dynamics in the whole circuit and eventually regulate the PC output. This review elaborates current knowledge on cerebellar inhibitory interneurons [Golgi cells, Lugaro cells (LCs), basket cells (BCs) and stellate cells (SCs)], starting from their ontogenesis and moving up to their morphological, physiological and plastic properties, and integrates this knowledge with that on the more renown granule cells and PCs. We will focus on the circuit loops in which these interneurons are involved and on the way they generate feed-forward, feedback and lateral inhibition along with complex spatio-temporal response dynamics. In this perspective, inhibitory interneurons emerge as the real controllers of cerebellar functioning.
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Affiliation(s)
- Francesca Prestori
- Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
| | - Lisa Mapelli
- Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
| | - Egidio D'Angelo
- Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy.,IRCCS Mondino Foundation, Pavia, Italy
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Trent S, Hall J, Connelly WM, Errington AC. Cyfip1 Haploinsufficiency Does Not Alter GABA A Receptor δ-Subunit Expression and Tonic Inhibition in Dentate Gyrus PV + Interneurons and Granule Cells. eNeuro 2019; 6:ENEURO.0364-18.2019. [PMID: 31209152 PMCID: PMC6635810 DOI: 10.1523/eneuro.0364-18.2019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 05/28/2019] [Accepted: 05/31/2019] [Indexed: 12/01/2022] Open
Abstract
Copy number variation (CNV) at chromosomal region 15q11.2 is linked to increased risk of neurodevelopmental disorders including autism and schizophrenia. A significant gene at this locus is cytoplasmic fragile X mental retardation protein (FMRP) interacting protein 1 (CYFIP1). CYFIP1 protein interacts with FMRP, whose monogenic absence causes fragile X syndrome (FXS). Fmrp knock-out has been shown to reduce tonic GABAergic inhibition by interacting with the δ-subunit of the GABAA receptor (GABAAR). Using in situ hybridization (ISH), qPCR, Western blotting techniques, and patch clamp electrophysiology in brain slices from a Cyfip1 haploinsufficient mouse, we examined δ-subunit mediated tonic inhibition in the dentate gyrus (DG). In wild-type (WT) mice, DG granule cells (DGGCs) responded to the δ-subunit-selective agonist THIP with significantly increased tonic currents. In heterozygous mice, no significant difference was observed in THIP-evoked currents in DGGCs. Phasic GABAergic inhibition in DGGC was also unaltered with no difference in properties of spontaneous IPSCs (sIPSCs). Additionally, we demonstrate that DG granule cell layer (GCL) parvalbumin-positive interneurons (PV+-INs) have functional δ-subunit-mediated tonic GABAergic currents which, unlike DGGC, are also modulated by the α1-selective drug zolpidem. Similar to DGGC, both IPSCs and THIP-evoked currents in PV+-INs were not different between Cyfip1 heterozygous and WT mice. Supporting our electrophysiological data, we found no significant change in hippocampal δ-subunit mRNA expression or protein level and no change in α1/α4-subunit mRNA expression. Thus, Cyfip1 haploinsufficiency, mimicking human 15q11.2 microdeletion syndrome, does not alter hippocampal phasic or tonic GABAergic inhibition, substantially differing from the Fmrp knock-out mouse model.
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Affiliation(s)
- Simon Trent
- Neuroscience and Mental Health Research Institute, School of Medicine, Cardiff University, Cardiff, CF24 4HQ, United Kingdom
| | - Jeremy Hall
- Neuroscience and Mental Health Research Institute, School of Medicine, Cardiff University, Cardiff, CF24 4HQ, United Kingdom
| | - William M Connelly
- School of Medicine, University of Tasmania, Hobart, Tasmania 7000, Australia
| | - Adam C Errington
- Neuroscience and Mental Health Research Institute, School of Medicine, Cardiff University, Cardiff, CF24 4HQ, United Kingdom
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Maniezzi C, Talpo F, Spaiardi P, Toselli M, Biella G. Oxytocin Increases Phasic and Tonic GABAergic Transmission in CA1 Region of Mouse Hippocampus. Front Cell Neurosci 2019; 13:178. [PMID: 31133808 PMCID: PMC6516053 DOI: 10.3389/fncel.2019.00178] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Accepted: 04/12/2019] [Indexed: 11/17/2022] Open
Abstract
Oxytocin is a neuropeptide that plays important peripheral and central neuromodulatory functions. Our data show that, following activation of oxytocin receptors (OtRs) with the selective agonist TGOT (Thr4,Gly7-oxytocin), a significant increase in frequency and amplitude of spontaneous inhibitory postsynaptic currents (sIPSC) occurred in hippocampal CA1 pyramidal neurons (PYR) in mice. TGOT affected also sIPSC deactivation kinetics, suggesting the involvement of perisynaptic GABAA receptors (GABAARs) as well. By contrast, TGOT did not cause significant changes in frequency, amplitude or deactivation kinetics of miniature IPSC, suggesting that the effects elicited by the agonist are strictly dependent on the firing activity of presynaptic neurons. Moreover, TGOT was able to modulate tonic GABAergic current mediated by extrasynaptic GABAARs expressed by PYRs. Consistently, at spike threshold TGOT induced in most PYRs a significant membrane hyperpolarization and a decrease in firing rate. The source of increased inhibition onto PYRs was represented by stuttering fast-spiking GABAergic interneurons (INs) that directly respond to TGOT with a depolarization and an increase in their firing rate. One putative ionic mechanism underlying this effect could be represented by OtR activation-induced up-modulation of L-type Ca2+ channels. In conclusion, our results indicate that oxytocin can influence the activity of a subclass of hippocampal GABAergic INs and therefore regulate the operational modes of the downstream PYRs by increasing phasic and tonic GABAergic transmission in CA1 region of mouse hippocampus.
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Affiliation(s)
- Claudia Maniezzi
- Laboratory of Physiology, Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Francesca Talpo
- Laboratory of Physiology, Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Paolo Spaiardi
- Neurophysiology Unit, Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
| | - Mauro Toselli
- Laboratory of Physiology, Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Gerardo Biella
- Laboratory of Physiology, Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
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O'Neill N, Sylantyev S. The Functional Role of Spontaneously Opening GABA A Receptors in Neural Transmission. Front Mol Neurosci 2019; 12:72. [PMID: 30983968 PMCID: PMC6447609 DOI: 10.3389/fnmol.2019.00072] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 03/08/2019] [Indexed: 12/22/2022] Open
Abstract
Ionotropic type of γ-aminobutyric acid receptors (GABAARs) produce two forms of inhibitory signaling: phasic inhibition generated by rapid efflux of neurotransmitter GABA into the synaptic cleft with subsequent binding to GABAARs, and tonic inhibition generated by persistent activation of extrasynaptic and/or perisynaptic GABAARs by GABA continuously present in the extracellular space. It is widely accepted that phasic and tonic GABAergic inhibition is mediated by receptor groups of distinct subunit composition and modulated by different cytoplasmic mechanisms. Recently, however, it has been demonstrated that spontaneously opening GABAARs (s-GABAARs), which do not need GABA binding to enter an active state, make a significant input into tonic inhibitory signaling. Due to GABA-independent action mode, s-GABAARs promise new safer options for therapy of neural disorders (such as epilepsy) devoid of side effects connected to abnormal fluctuations of GABA concentration in the brain. However, despite the potentially important role of s-GABAARs in neural signaling, they still remain out of focus of neuroscience studies, to a large extent due to technical difficulties in their experimental research. Here, we summarize present data on s-GABAARs functional properties and experimental approaches that allow isolation of s-GABAARs effects from those of conventional (GABA-dependent) GABAARs.
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Affiliation(s)
- Nathanael O'Neill
- Center for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Sergiy Sylantyev
- Center for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
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