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Tsai YC, ElGrawani W, Muheim C, Spinnler A, Campbell BFN, Lasic D, Hleihil M, Brown SA, Tyagarajan SK. Modulation of sleep/wake patterns by gephyrin phosphorylation status. Eur J Neurosci 2024. [PMID: 39032002 DOI: 10.1111/ejn.16464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Revised: 06/13/2024] [Accepted: 07/01/2024] [Indexed: 07/22/2024]
Abstract
Sleep/wake cycles intricately shape physiological activities including cognitive brain functions, yet the precise molecular orchestrators of sleep remain elusive. Notably, the clinical impact of benzodiazepine drugs underscores the pivotal role of GABAergic neurotransmission in sleep regulation. However, the specific contributions of distinct GABAA receptor subtypes and their principal scaffolding protein, gephyrin, in sleep dynamics remain unclear. The evolving role of synaptic phospho-proteome alterations at excitatory and inhibitory synapses suggests a potential avenue for modulating gephyrin and, consequently, GABAARs for sleep through on-demand kinase recruitment. Our study unveils the distinctive roles of two prevalent GABAA receptor subtypes, α1- and α2-GABAARs, in influencing sleep duration and electrical sleep activity. Notably, the absence of α1-GABAARs emerges as central in sleep regulation, manifesting significant alterations in both non-rapid eye movement (NREM) and rapid eye movement (REM) sleep during dark or active phases, accompanied by altered electroencephalogram (EEG) patterns across various frequencies. Gephyrin proteomics analysis reveals sleep/wake-dependent interactions with a repertoire of known and novel kinases. Crucially, we identify the regulation of gephyrin interaction with ERK1/2, and phosphorylations at serines 268 and 270 are dictated by sleep/wake cycles. Employing AAV-eGFP-gephyrin or its phospho-null variant (S268A/S270A), we disrupt sleep either globally or locally to demonstrate gephyrin phosphorylation as a sleep regulator. In summary, our findings support the local cortical sleep hypothesis and we unveil a molecular mechanism operating at GABAergic synapses, providing critical insights into the intricate regulation of sleep.
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Affiliation(s)
- Yuan-Chen Tsai
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
- Neuroscience Centre Zurich, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Waleed ElGrawani
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
- Neuroscience Centre Zurich, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Christine Muheim
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
- Neuroscience Centre Zurich, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Andrea Spinnler
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
- Neuroscience Centre Zurich, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Benjamin F N Campbell
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
- Neuroscience Centre Zurich, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Denis Lasic
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
- Neuroscience Centre Zurich, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Mohammad Hleihil
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
| | - Steven A Brown
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
- Neuroscience Centre Zurich, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Shiva K Tyagarajan
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
- Neuroscience Centre Zurich, University of Zurich and ETH Zurich, Zurich, Switzerland
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2
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Wu K, Lu W. GABAergic synaptic transmission and plasticity oscillate across sleep and wake. Neural Regen Res 2023; 18:2647-2648. [PMID: 37449604 DOI: 10.4103/1673-5374.373665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/18/2023] Open
Affiliation(s)
- Kunwei Wu
- Jiangsu Province Key Laboratory of Anesthesiology, Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application, NMPA Key Laboratory, for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou, Jiangsu Province, China
| | - Wei Lu
- Synapse and Neural Circuit Research Section, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD, USA
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3
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Nuwer JL, Povysheva N, Jacob TC. Long-term α5 GABA A receptor negative allosteric modulator treatment reduces NMDAR-mediated neuronal excitation and maintains basal neuronal inhibition. Neuropharmacology 2023; 237:109587. [PMID: 37270156 PMCID: PMC10527172 DOI: 10.1016/j.neuropharm.2023.109587] [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: 03/27/2023] [Revised: 04/27/2023] [Accepted: 05/09/2023] [Indexed: 06/05/2023]
Abstract
α5 subunit-containing GABA type-A receptors (α5 GABAARs) are enriched in the hippocampus and play critical roles in neurodevelopment, synaptic plasticity, and cognition. α5 GABAAR preferring negative allosteric modulators (α5 NAMs) show promise mitigating cognitive impairment in preclinical studies of conditions characterized by excess GABAergic inhibition, including Down syndrome and memory deficits post-anesthesia. However, previous studies have primarily focused on acute application or single-dose α5 NAM treatment. Here, we measured the effects of chronic (7-day) in vitro treatment with L-655,708 (L6), a highly selective α5 NAM, on glutamatergic and GABAergic synapses in rat hippocampal neurons. We previously showed that 2-day in vitro treatment with L6 enhanced synaptic levels of the glutamate NMDA receptor (NMDAR) GluN2A subunit without modifying surface α5 GABAAR expression, inhibitory synapse function, or L6 sensitivity. We hypothesized that chronic L6 treatment would further increase synaptic GluN2A subunit levels while maintaining GABAergic inhibition and L6 efficacy, thus increasing neuronal excitation and glutamate-evoked intracellular calcium responses. Immunofluorescence experiments revealed that 7-day L6 treatment slightly increased the synaptic levels of gephyrin and surface α5 GABAARs. Functional studies showed that chronic α5 NAM treatment did not alter inhibition or α5 NAM sensitivity. Surprisingly, chronic L6 exposure decreased surface levels of GluN2A and GluN2B subunits, concurrent with reduced NMDAR-mediated neuronal excitation as seen by faster synaptic decay rates and reduced glutamate-evoked calcium responses. Together, these results show that chronic in vitro treatment with an α5 NAM leads to subtle homeostatic changes in inhibitory and excitatory synapses that suggest an overall dampening of excitability.
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Affiliation(s)
- Jessica L Nuwer
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Nadya Povysheva
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA
| | - Tija C Jacob
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
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4
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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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5
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Khodaei S, Wang DS, Orser BA. Reduced excitatory neurotransmission in the hippocampus after inflammation and sevoflurane anaesthesia. BJA OPEN 2023; 6:100143. [PMID: 37588178 PMCID: PMC10430808 DOI: 10.1016/j.bjao.2023.100143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 03/29/2023] [Accepted: 04/21/2023] [Indexed: 08/18/2023]
Abstract
Background Inflammation and general anaesthesia likely contribute to perioperative neurocognitive disorders, possibly by causing a neuronal imbalance of excitation and inhibition. We showed previously that treatment with lipopolysaccharide (LPS) and sevoflurane causes a sustained increase in a tonic inhibitory conductance in the hippocampus; however, whether excitatory neurotransmission is also altered remains unknown. The goal of this study was to examine excitatory synaptic currents in the hippocampus after treatment with LPS and sevoflurane. Synaptic plasticity in the hippocampus, a cellular correlate of learning and memory, was also studied. Methods Mice were injected with vehicle or LPS (1 mg kg-1 i.p.), and after 24 h they were then exposed to vehicle or sevoflurane (2.3%; 2 h). Hippocampal slices were prepared 48 h later. Excitatory synaptic currents were recorded from pyramidal neurones. Long-term potentiation (LTP) and long-term depression (LTD) were studied in the Schaffer collateral-cornu ammonis 1 pathway. Results The amplitude of miniature excitatory postsynaptic currents (EPSCs) was reduced after LPS+sevoflurane (P<0.001), whereas that of spontaneous EPSCs was unaltered, as evidenced by cumulative distribution plots. The frequency, area, and kinetics of both miniature and spontaneous EPSCs were unchanged, as were LTP and LTD. Conclusions The reduced amplitude of miniature EPSCs, coupled with the previously reported increase in tonic inhibition, indicates that the combination of LPS and sevoflurane markedly disrupts the balance of excitation and inhibition. Restoring this balance by pharmacologically enhancing excitatory neurotransmission and inhibiting the tonic current may represent an effective therapeutic option for perioperative neurocognitive disorders.
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Affiliation(s)
- Shahin Khodaei
- Department of Physiology, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Dian-Shi Wang
- Department of Physiology, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Beverley A. Orser
- Department of Physiology, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
- Department of Anesthesiology & Pain Medicine, Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
- Department of Anesthesia, Sunnybrook Health Sciences Centre, Toronto, ON, Canada
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6
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Wu K, Shepard RD, Castellano D, Han W, Tian Q, Dong L, Lu W. Shisa7 phosphorylation regulates GABAergic transmission and neurodevelopmental behaviors. Neuropsychopharmacology 2022; 47:2160-2170. [PMID: 35534528 PMCID: PMC9556544 DOI: 10.1038/s41386-022-01334-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 03/27/2022] [Accepted: 04/19/2022] [Indexed: 11/09/2022]
Abstract
GABA-A receptors (GABAARs) are crucial for development and function of the brain. Altered GABAergic transmission is hypothesized to be involved in neurodevelopmental disorders. Recently, we identified Shisa7 as a GABAAR auxiliary subunit that modulates GABAAR trafficking and GABAergic transmission. However, the underlying molecular mechanisms remain elusive. Here we generated a knock-in (KI) mouse line that is phospho-deficient at a phosphorylation site in Shisa7 (S405) and combined with electrophysiology, imaging and behavioral assays to illustrate the role of this site in GABAergic transmission and plasticity as well as behaviors. We found that expression of phospho-deficient mutants diminished α2-GABAAR trafficking in heterologous cells. Additionally, α1/α2/α5-GABAAR surface expression and GABAergic inhibition were decreased in hippocampal neurons in KI mice. Moreover, chemically induced inhibitory long-term potentiation was abolished in KI mice. Lastly, KI mice exhibited hyperactivity, increased grooming and impaired sleep homeostasis. Collectively, our study reveals a phosphorylation site critical for Shisa7-dependent GABAARs trafficking which contributes to behavioral endophenotypes displayed in neurodevelopmental disorders.
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Affiliation(s)
- Kunwei Wu
- Synapse and Neural Circuit Research Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Ryan David Shepard
- Synapse and Neural Circuit Research Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, 20892, USA
| | - David Castellano
- Synapse and Neural Circuit Research Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Wenyan Han
- Synapse and Neural Circuit Research Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Qingjun Tian
- Synapse and Neural Circuit Research Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Lijin Dong
- Genetic Engineering Core, National Eye Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Wei Lu
- Synapse and Neural Circuit Research Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, 20892, USA.
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7
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Hari K, Lucas-Osma AM, Metz K, Lin S, Pardell N, Roszko DA, Black S, Minarik A, Singla R, Stephens MJ, Pearce RA, Fouad K, Jones KE, Gorassini MA, Fenrich KK, Li Y, Bennett DJ. GABA facilitates spike propagation through branch points of sensory axons in the spinal cord. Nat Neurosci 2022; 25:1288-1299. [PMID: 36163283 PMCID: PMC10042549 DOI: 10.1038/s41593-022-01162-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Accepted: 08/11/2022] [Indexed: 11/09/2022]
Abstract
Movement and posture depend on sensory feedback that is regulated by specialized GABAergic neurons (GAD2+) that form axo-axonic contacts onto myelinated proprioceptive sensory axons and are thought to be inhibitory. However, we report here that activating GAD2+ neurons directly with optogenetics or indirectly by cutaneous stimulation actually facilitates sensory feedback to motor neurons in rodents and humans. GABAA receptors located at or near nodes of Ranvier of sensory axons cause this facilitation by preventing spike propagation failure at the many axon branch points, which is otherwise common without GABA. In contrast, GABAA receptors are generally lacking from axon terminals and so cannot inhibit transmitter release onto motor neurons, unlike GABAB receptors that cause presynaptic inhibition. GABAergic innervation near nodes and branch points allows individual branches to function autonomously, with GAD2+ neurons regulating which branches conduct, adding a computational layer to the neuronal networks generating movement and likely generalizing to other central nervous system axons.
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Affiliation(s)
- Krishnapriya Hari
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Ana M Lucas-Osma
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada.,Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, AB, Canada
| | - Krista Metz
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Shihao Lin
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Noah Pardell
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - David A Roszko
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Sophie Black
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Anna Minarik
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Rahul Singla
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Marilee J Stephens
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada.,Department of Biomedical Engineering, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Robert A Pearce
- Department of Anesthesiology, University of Wisconsin-Madison, Madison, WI, USA
| | - Karim Fouad
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada.,Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, AB, Canada
| | - Kelvin E Jones
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada.,Faculty of Kinesiology, Sport and Recreation, University of Alberta, Edmonton, AB, Canada
| | - Monica A Gorassini
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada.,Department of Biomedical Engineering, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Keith K Fenrich
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada.,Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, AB, Canada
| | - Yaqing Li
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada.,Department of Cell Biology, Emory University, Atlanta, GA, USA
| | - David J Bennett
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada. .,Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, AB, Canada.
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Excitatory Synaptic Transmission in Ischemic Stroke: A New Outlet for Classical Neuroprotective Strategies. Int J Mol Sci 2022; 23:ijms23169381. [PMID: 36012647 PMCID: PMC9409263 DOI: 10.3390/ijms23169381] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 08/15/2022] [Accepted: 08/17/2022] [Indexed: 01/01/2023] Open
Abstract
Stroke is one of the leading causes of death and disability in the world, of which ischemia accounts for the majority. There is growing evidence of changes in synaptic connections and neural network functions in the brain of stroke patients. Currently, the studies on these neurobiological alterations mainly focus on the principle of glutamate excitotoxicity, and the corresponding neuroprotective strategies are limited to blocking the overactivation of ionic glutamate receptors. Nevertheless, it is disappointing that these treatments often fail because of the unspecificity and serious side effects of the tested drugs in clinical trials. Thus, in the prevention and treatment of stroke, finding and developing new targets of neuroprotective intervention is still the focus and goal of research in this field. In this review, we focus on the whole processes of glutamatergic synaptic transmission and highlight the pathological changes underlying each link to help develop potential therapeutic strategies for ischemic brain damage. These strategies include: (1) controlling the synaptic or extra-synaptic release of glutamate, (2) selectively blocking the action of the glutamate receptor NMDAR subunit, (3) increasing glutamate metabolism, and reuptake in the brain and blood, and (4) regulating the glutamate system by GABA receptors and the microbiota–gut–brain axis. Based on these latest findings, it is expected to promote a substantial understanding of the complex glutamate signal transduction mechanism, thereby providing excellent neuroprotection research direction for human ischemic stroke (IS).
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Tipton AE, Russek SJ. Regulation of Inhibitory Signaling at the Receptor and Cellular Level; Advances in Our Understanding of GABAergic Neurotransmission and the Mechanisms by Which It Is Disrupted in Epilepsy. Front Synaptic Neurosci 2022; 14:914374. [PMID: 35874848 PMCID: PMC9302637 DOI: 10.3389/fnsyn.2022.914374] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 05/17/2022] [Indexed: 11/13/2022] Open
Abstract
Inhibitory signaling in the brain organizes the neural circuits that orchestrate how living creatures interact with the world around them and how they build representations of objects and ideas. Without tight control at multiple points of cellular engagement, the brain’s inhibitory systems would run down and the ability to extract meaningful information from excitatory events would be lost leaving behind a system vulnerable to seizures and to cognitive decline. In this review, we will cover many of the salient features that have emerged regarding the dynamic regulation of inhibitory signaling seen through the lens of cell biology with an emphasis on the major building blocks, the ligand-gated ion channel receptors that are the first transduction point when the neurotransmitter GABA is released into the synapse. Epilepsy association will be used to indicate importance of key proteins and their pathways to brain function and to introduce novel areas for therapeutic intervention.
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Affiliation(s)
- Allison E. Tipton
- Graduate Program for Neuroscience, Boston University, Boston, MA, United States
- Biomolecular Pharmacology Program, Boston University School of Medicine, Boston, MA, United States
- Boston University MD/PhD Training Program, Boston, MA, United States
| | - Shelley J. Russek
- Biomolecular Pharmacology Program, Boston University School of Medicine, Boston, MA, United States
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA, United States
- Center for Systems Neuroscience, Boston University, Boston, MA, United States
- Boston University MD/PhD Training Program, Boston, MA, United States
- *Correspondence: Shelley J. Russek,
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10
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Rosenbrock H, Dorner-Ciossek C, Giovannini R, Schmid B, Schuelert N. Effects of the glycine transporter-1 inhibitor iclepertin (BI 425809) on sensory processing, neural network function, and cognition in animal models related to schizophrenia. J Pharmacol Exp Ther 2022; 382:223-232. [PMID: 35661632 DOI: 10.1124/jpet.121.001071] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 05/04/2022] [Indexed: 11/22/2022] Open
Abstract
N-methyl-D-aspartate (NMDA) receptor hypofunction leading to neural network dysfunction is thought to play an important role in the pathophysiology of cognitive impairment associated with schizophrenia (CIAS). Increasing extracellular concentrations of the NMDA receptor co-agonist glycine through inhibition of glycine transporter-1 (GlyT1) has the potential to treat CIAS by improving cortical network function through enhanced glutamatergic signaling. Indeed, the novel GlyT1 inhibitor iclepertin (BI 425809) improved cognition in a recent clinical study in patients with schizophrenia. The present study tested the ability of iclepertin to reverse MK-801-induced deficits in auditory sensory processing and cortical network function using electroencephalography (EEG) to measure auditory event-related potentials (AERP) and 40 Hz auditory steady-state response (ASSR). In addition, improvements in memory performance with iclepertin were evaluated using the T-maze spontaneous alternation test in MK-801-treated mice and the social recognition test in naïve rats. Iclepertin reversed MK-801-induced deficits in the AERP readouts N1 amplitude and N1 gating, as well as 40 Hz ASSR power and inter-trial coherence. Additionally, iclepertin significantly attenuated an MK-801-induced increase in basal gamma power. Furthermore, iclepertin reversed MK-801-induced working memory deficits in mice and improved social recognition memory performance in rats. Overall, this study demonstrates that inhibition of GlyT1 is sufficient to attenuate MK-801-induced deficits in translatable EEG parameters relevant to schizophrenia. Moreover, iclepertin showed memory-enhancing effects in rodent cognition tasks, further demonstrating the potential for GlyT1 inhibition to treat CIAS. Significance Statement Despite the significant patient burden caused by cognitive impairment associated with schizophrenia, there are currently no approved pharmacotherapies. In this preclinical study, the novel glycine transporter inhibitor iclepertin (BI 425809) reversed sensory processing deficits and neural network dysfunction evoked by inhibition of N-methyl-D-aspartate (NMDA) receptors, and enhanced working memory performance and social recognition in rodents. These findings support previous clinical evidence for the pro-cognitive effects of iclepertin.
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Affiliation(s)
- Holger Rosenbrock
- CNS Discovery Research, Boehringer Ingelheim Pharma GmbH & Co. KG, Germany
| | | | | | - Bernhard Schmid
- Drug Discovery Sciences, Boehringer Ingelheim Pharma GmbH & Co. KG, Germany
| | - Niklas Schuelert
- CNS Discovery Research, Boehringer Ingelheim Pharma GmbH & Co. KG, Germany
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11
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Chapman CA, Nuwer JL, Jacob TC. The Yin and Yang of GABAergic and Glutamatergic Synaptic Plasticity: Opposites in Balance by Crosstalking Mechanisms. Front Synaptic Neurosci 2022; 14:911020. [PMID: 35663370 PMCID: PMC9160301 DOI: 10.3389/fnsyn.2022.911020] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 04/26/2022] [Indexed: 01/12/2023] Open
Abstract
Synaptic plasticity is a critical process that regulates neuronal activity by allowing neurons to adjust their synaptic strength in response to changes in activity. Despite the high proximity of excitatory glutamatergic and inhibitory GABAergic postsynaptic zones and their functional integration within dendritic regions, concurrent plasticity has historically been underassessed. Growing evidence for pathological disruptions in the excitation and inhibition (E/I) balance in neurological and neurodevelopmental disorders indicates the need for an improved, more "holistic" understanding of synaptic interplay. There continues to be a long-standing focus on the persistent strengthening of excitation (excitatory long-term potentiation; eLTP) and its role in learning and memory, although the importance of inhibitory long-term potentiation (iLTP) and depression (iLTD) has become increasingly apparent. Emerging evidence further points to a dynamic dialogue between excitatory and inhibitory synapses, but much remains to be understood regarding the mechanisms and extent of this exchange. In this mini-review, we explore the role calcium signaling and synaptic crosstalk play in regulating postsynaptic plasticity and neuronal excitability. We examine current knowledge on GABAergic and glutamatergic synapse responses to perturbances in activity, with a focus on postsynaptic plasticity induced by short-term pharmacological treatments which act to either enhance or reduce neuronal excitability via ionotropic receptor regulation in neuronal culture. To delve deeper into potential mechanisms of synaptic crosstalk, we discuss the influence of synaptic activity on key regulatory proteins, including kinases, phosphatases, and synaptic structural/scaffolding proteins. Finally, we briefly suggest avenues for future research to better understand the crosstalk between glutamatergic and GABAergic synapses.
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Affiliation(s)
| | | | - Tija C. Jacob
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
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