1
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Wang DS, Ju L, Pinguelo AG, Kaneshwaran K, Haffey SC, Lecker I, Gohil H, Wheeler MB, Kaustov L, Ariza A, Yu M, Volchuk A, Steinberg BE, Goldenberg NM, Orser BA. Crosstalk between GABA A receptors in astrocytes and neurons triggered by general anesthetic drugs. Transl Res 2024; 267:39-53. [PMID: 38042478 DOI: 10.1016/j.trsl.2023.11.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Revised: 11/17/2023] [Accepted: 11/29/2023] [Indexed: 12/04/2023]
Abstract
General anesthetic drugs cause cognitive deficits that persist after the drugs have been eliminated. Astrocytes may contribute to such cognition-impairing effects through the release of one or more paracrine factors that increase a tonic inhibitory conductance generated by extrasynaptic γ-aminobutyric acid type A (GABAA) receptors in hippocampal neurons. The mechanisms underlying this astrocyte-to-neuron crosstalk remain unknown. Interestingly, astrocytes express anesthetic-sensitive GABAA receptors. Here, we tested the hypothesis that anesthetic drugs activate astrocytic GABAA receptors to initiate crosstalk leading to a persistent increase in extrasynaptic GABAA receptor function in neurons. We also investigated the signaling pathways in neurons and aimed to identify the paracrine factors released from astrocytes. Astrocytes and neurons from mice were grown in primary cell cultures and studied using in vitro electrophysiological and biochemical assays. We discovered that the commonly used anesthetics etomidate (injectable) and sevoflurane (inhaled) stimulated astrocytic GABAA receptors, which in turn promoted the release paracrine factors, that increased the tonic current in neurons via a p38 MAPK-dependent signaling pathway. The increase in tonic current was mimicked by exogenous IL-1β and abolished by blocking IL-1 receptors; however, unexpectedly, IL-1β and other cytokines were not detected in astrocyte-conditioned media. In summary, we have identified a novel form of crosstalk between GABAA receptors in astrocytes and neurons that engages a p38 MAPK-dependent pathway. Brief commentary BACKGROUND: Many older patients experience cognitive deficits after surgery. Anesthetic drugs may be a contributing factor as they cause a sustained increase in the function of "memory blocking" extrasynaptic GABAA receptors in neurons. Interestingly, astrocytes are required for this increase; however, the mechanisms underlying the astrocyte-to-neuron crosstalk remain unknown. TRANSLATIONAL SIGNIFICANCE: We discovered that commonly used general anesthetic drugs stimulate GABAA receptors in astrocytes, which in turn release paracrine factors that trigger a persistent increase in extrasynaptic GABAA receptor function in neurons via p38 MAPK. This novel form of crosstalk may contribute to persistent cognitive deficits after general anesthesia and surgery.
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Affiliation(s)
- Dian-Shi Wang
- Department of Physiology, Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Li Ju
- Department of Physiology, Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Arsène G Pinguelo
- Department of Physiology, Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Kirusanthy Kaneshwaran
- Department of Physiology, Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Sean C Haffey
- Department of Physiology, Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Irene Lecker
- Department of Physiology, Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Himaben Gohil
- Department of Physiology, Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Michael B Wheeler
- Department of Physiology, Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada; Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Lilia Kaustov
- Department of Anesthesia, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada
| | - Anthony Ariza
- Department of Physiology, Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - MeiFeng Yu
- Department of Physiology, Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Allen Volchuk
- Program in Cell Biology, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Benjamin E Steinberg
- Program in Cell Biology, Hospital for Sick Children, Toronto, Ontario, Canada; Department of Anesthesia and Pain Medicine, Hospital for Sick Children, Toronto, Ontario, Canada; Department of Anesthesiology & Pain Medicine, Temerty Faculty of Medicine, University of Toronto, Room 3318, Medical Sciences Building, 1 King's College Circle, Ontario M5S 1A8, Canada
| | - Neil M Goldenberg
- Department of Physiology, Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada; Department of Anesthesia and Pain Medicine, Hospital for Sick Children, Toronto, Ontario, Canada; Department of Anesthesiology & Pain Medicine, Temerty Faculty of Medicine, University of Toronto, Room 3318, Medical Sciences Building, 1 King's College Circle, Ontario M5S 1A8, Canada; Program in Neurosciences & Mental Health, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Beverley A Orser
- Department of Physiology, Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada; Department of Anesthesia, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada; Department of Anesthesiology & Pain Medicine, Temerty Faculty of Medicine, University of Toronto, Room 3318, Medical Sciences Building, 1 King's College Circle, Ontario M5S 1A8, Canada.
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2
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Niepoth N, Merritt JR, Uminski M, Lei E, Esquibies VS, Bando IB, Hernandez K, Gebhardt C, Wacker SA, Lutzu S, Poudel A, Soma KK, Rudolph S, Bendesky A. Evolution of a novel adrenal cell type that promotes parental care. Nature 2024; 629:1082-1090. [PMID: 38750354 PMCID: PMC11329292 DOI: 10.1038/s41586-024-07423-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 04/15/2024] [Indexed: 05/25/2024]
Abstract
Cell types with specialized functions fundamentally regulate animal behaviour, and yet the genetic mechanisms that underlie the emergence of novel cell types and their consequences for behaviour are not well understood1. Here we show that the monogamous oldfield mouse (Peromyscus polionotus) has recently evolved a novel cell type in the adrenal gland that expresses the enzyme AKR1C18, which converts progesterone into 20α-hydroxyprogesterone. We then demonstrate that 20α-hydroxyprogesterone is more abundant in oldfield mice, where it induces monogamous-typical parental behaviours, than in the closely related promiscuous deer mice (Peromyscus maniculatus). Using quantitative trait locus mapping in a cross between these species, we ultimately find interspecific genetic variation that drives expression of the nuclear protein GADD45A and the glycoprotein tenascin N, which contribute to the emergence and function of this cell type in oldfield mice. Our results provide an example by which the recent evolution of a new cell type in a gland outside the brain contributes to the evolution of social behaviour.
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Affiliation(s)
- Natalie Niepoth
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
- Department of Ecology, Evolution and Environmental Biology, Columbia University, New York, NY, USA
| | - Jennifer R Merritt
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
- Department of Ecology, Evolution and Environmental Biology, Columbia University, New York, NY, USA
| | - Michelle Uminski
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
- Department of Ecology, Evolution and Environmental Biology, Columbia University, New York, NY, USA
| | - Emily Lei
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
- Department of Ecology, Evolution and Environmental Biology, Columbia University, New York, NY, USA
| | - Victoria S Esquibies
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
- Department of Ecology, Evolution and Environmental Biology, Columbia University, New York, NY, USA
| | - Ina B Bando
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
- Department of Ecology, Evolution and Environmental Biology, Columbia University, New York, NY, USA
| | - Kimberly Hernandez
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
- Department of Ecology, Evolution and Environmental Biology, Columbia University, New York, NY, USA
| | - Christoph Gebhardt
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
- Department of Ecology, Evolution and Environmental Biology, Columbia University, New York, NY, USA
| | - Sarah A Wacker
- Department of Chemistry and Biochemistry, Manhattan College, New York, NY, USA
| | - Stefano Lutzu
- Department of Neuroscience, Albert Einstein College of Medicine, New York, NY, USA
- Department of Psychiatry and Behavioral Sciences, Albert Einstein College of Medicine, New York, NY, USA
| | - Asmita Poudel
- Department of Psychology, University of British Columbia, Vancouver, British Columbia, Canada
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada
| | - Kiran K Soma
- Department of Psychology, University of British Columbia, Vancouver, British Columbia, Canada
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada
| | - Stephanie Rudolph
- Department of Neuroscience, Albert Einstein College of Medicine, New York, NY, USA
- Department of Psychiatry and Behavioral Sciences, Albert Einstein College of Medicine, New York, NY, USA
| | - Andres Bendesky
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA.
- Department of Ecology, Evolution and Environmental Biology, Columbia University, New York, NY, USA.
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3
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Potenzieri A, Uccella S, Preiti D, Pisoni M, Rosati S, Lavarello C, Bartolucci M, Debellis D, Catalano F, Petretto A, Nobili L, Fellin T, Tucci V, Ramenghi LA, Savardi A, Cancedda L. Early IGF-1 receptor inhibition in mice mimics preterm human brain disorders and reveals a therapeutic target. SCIENCE ADVANCES 2024; 10:eadk8123. [PMID: 38427732 PMCID: PMC10906931 DOI: 10.1126/sciadv.adk8123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Accepted: 01/29/2024] [Indexed: 03/03/2024]
Abstract
Besides recent advances in neonatal care, preterm newborns still develop sex-biased behavioral alterations. Preterms fail to receive placental insulin-like growth factor-1 (IGF-1), a major fetal growth hormone in utero, and low IGF-1 serum levels correlate with preterm poor neurodevelopmental outcomes. Here, we mimicked IGF-1 deficiency of preterm newborns in mice by perinatal administration of an IGF-1 receptor antagonist. This resulted in sex-biased brain microstructural, functional, and behavioral alterations, resembling those of ex-preterm children, which we characterized performing parallel mouse/human behavioral tests. Pharmacological enhancement of GABAergic tonic inhibition by the U.S. Food and Drug Administration-approved drug ganaxolone rescued functional/behavioral alterations in mice. Establishing an unprecedented mouse model of prematurity, our work dissects the mechanisms at the core of abnormal behaviors and identifies a readily translatable therapeutic strategy for preterm brain disorders.
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Affiliation(s)
- Alberto Potenzieri
- Brain Development and Disease Laboratory, Istituto Italiano di Tecnologia, via Morego, 30, 16163 Genoa, Italy
- Università degli Studi di Genova, via Balbi, 5, 16126 Genoa, Italy
| | - Sara Uccella
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DINOGMI), University of Genoa, 16132 Genoa, Italy
- Child Neuropsychiatry Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy
- Patologia Neonatale, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Deborah Preiti
- Child Neuropsychiatry Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy
- Patologia Neonatale, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Matteo Pisoni
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, via Morego, 30, 16163 Genoa, Italy
| | - Silvia Rosati
- Brain Development and Disease Laboratory, Istituto Italiano di Tecnologia, via Morego, 30, 16163 Genoa, Italy
| | - Chiara Lavarello
- Core Facilities - Clinical Proteomics and Metabolomics, IRCCS Istituto Giannina Gaslini, via Gerolamo Gaslini 5, 16147 Genoa, Italy
| | - Martina Bartolucci
- Core Facilities - Clinical Proteomics and Metabolomics, IRCCS Istituto Giannina Gaslini, via Gerolamo Gaslini 5, 16147 Genoa, Italy
| | - Doriana Debellis
- Electron Microscopy Facility, Istituto Italiano di Tecnologia, via Morego, 30, 16163 Genoa, Italy
| | - Federico Catalano
- Electron Microscopy Facility, Istituto Italiano di Tecnologia, via Morego, 30, 16163 Genoa, Italy
| | - Andrea Petretto
- Core Facilities - Clinical Proteomics and Metabolomics, IRCCS Istituto Giannina Gaslini, via Gerolamo Gaslini 5, 16147 Genoa, Italy
| | - Lino Nobili
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DINOGMI), University of Genoa, 16132 Genoa, Italy
- Child Neuropsychiatry Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Tommaso Fellin
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, via Morego, 30, 16163 Genoa, Italy
| | - Valter Tucci
- Genetics and Epigenetics of Behavior (GEB) Laboratory, Istituto Italiano di Tecnologia, via Morego, 30, 16163 Genoa, Italy
| | - Luca A. Ramenghi
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DINOGMI), University of Genoa, 16132 Genoa, Italy
- Patologia Neonatale, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Annalisa Savardi
- Brain Development and Disease Laboratory, Istituto Italiano di Tecnologia, via Morego, 30, 16163 Genoa, Italy
| | - Laura Cancedda
- Brain Development and Disease Laboratory, Istituto Italiano di Tecnologia, via Morego, 30, 16163 Genoa, Italy
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4
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Seabrook LT, Peterson CS, Noble D, Sobey M, Tayyab T, Kenney T, Judge AK, Armstrong M, Lin S, Borgland SL. Short- and Long-Term High-Fat Diet Exposure Differentially Alters Phasic and Tonic GABAergic Signaling onto Lateral Orbitofrontal Pyramidal Neurons. J Neurosci 2023; 43:8582-8595. [PMID: 37793910 PMCID: PMC10727176 DOI: 10.1523/jneurosci.0831-23.2023] [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: 05/06/2023] [Revised: 08/26/2023] [Accepted: 09/21/2023] [Indexed: 10/06/2023] Open
Abstract
The chronic consumption of caloric dense high-fat foods is a major contributor to increased body weight, obesity, and other chronic health conditions. The orbitofrontal cortex (OFC) is critical in guiding decisions about food intake and is altered with diet-induced obesity. Obese rodents have altered morphologic and synaptic electrophysiological properties in the lateral orbitofrontal cortex (lOFC). Yet the time course by which exposure to a high-fat diet (HFD) induces these changes is poorly understood. Here, male mice are exposed to either short-term (7 d) or long-term (90 d) HFD. Long-term HFD exposure increases body weight, and glucose signaling compared with short-term HFD or a standard control diet (SCD). Both short and long-term HFD exposure increased the excitability of lOFC pyramidal neurons. However, phasic and tonic GABAergic signaling was differentially altered depending on HFD exposure length, such that tonic GABAergic signaling was decreased with early exposure to the HFD and phasic signaling was changed with long-term diet exposure. Furthermore, alterations in the short-term diet exposure were transient, as removal of the diet restored electrophysiological characteristics similar to mice fed SCD, whereas long-term HFD electrophysiological changes were persistent and remained after HFD removal. Finally, we demonstrate that changes in reward devaluation occur early with diet exposure. Together, these results suggest that the duration of HFD exposure differentially alters lOFC function and provides mechanistic insights into the susceptibility of the OFC to impairments in outcome devaluation.SIGNIFICANCE STATEMENT This study provides mechanistic insight on the impact of short-term and long-term high-fat diet (HFD) exposure on GABAergic function in the lateral orbitofrontal cortex (lOFC), a region known to guide decision-making. We find short-term HFD exposure induces transient changes in firing and tonic GABA action on lOFC pyramidal neurons, whereas long-term HFD induces obesity and has lasting changes on firing, tonic GABA and inhibitory synaptic transmission onto lOFC neurons. Given that GABAergic signaling in the lOFC can influence decision-making around food, these results have important implications in present society as palatable energy dense foods are abundantly available.
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Affiliation(s)
- Lauren T Seabrook
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, The University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Colleen S Peterson
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, The University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Duncan Noble
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, The University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Marissa Sobey
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, The University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Temoor Tayyab
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, The University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Tyra Kenney
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, The University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Allap K Judge
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, The University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Mataea Armstrong
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, The University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Shihao Lin
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, The University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Stephanie L Borgland
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, The University of Calgary, Calgary, Alberta T2N 4N1, Canada
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5
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Dhyani V, George K, Gare S, Venkatesh KV, Mitra K, Giri L. A computational model to uncover the biophysical underpinnings of neural firing heterogeneity in dissociated hippocampal cultures. Hippocampus 2023; 33:1208-1227. [PMID: 37705290 DOI: 10.1002/hipo.23575] [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: 09/01/2022] [Revised: 07/12/2023] [Accepted: 08/21/2023] [Indexed: 09/15/2023]
Abstract
Calcium (Ca2+ ) imaging reveals a variety of correlated firing in cultures of dissociated hippocampal neurons, pinpointing the non-synaptic paracrine release of glutamate as a possible mediator for such firing patterns, although the biophysical underpinnings remain unknown. An intriguing possibility is that extracellular glutamate could bind metabotropic receptors linked with inositol trisphosphate (IP3 ) mediated release of Ca2+ from the endoplasmic reticulum of individual neurons, thereby modulating neural activity in combination with sarco/endoplasmic reticulum Ca2+ transport ATPase (SERCA) and voltage-gated Ca2+ channels (VGCC). However, the possibility that such release may occur in different neuronal compartments and can be inherently stochastic poses challenges in the characterization of such interplay between various Ca2+ channels. Here we deploy biophysical modeling in association with Monte Carlo parameter sampling to characterize such interplay and successfully predict experimentally observed Ca2+ patterns. The results show that the neurotransmitter level at the plasma membrane is the extrinsic source of heterogeneity in somatic Ca2+ transients. Our analysis, in particular, identifies the origin of such heterogeneity to an intrinsic differentiation of hippocampal neurons in terms of multiple cellular properties pertaining to intracellular Ca2+ signaling, such as VGCC, IP3 receptor, and SERCA expression. In the future, the biophysical model and parameter estimation approach used in this study can be upgraded to predict the response of a system of interconnected neurons.
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Affiliation(s)
- Vaibhav Dhyani
- Department of Chemical Engineering, Indian Institute of Technology Hyderabad, Sangareddy, Telangana, India
- Optical Science Centre, Faculty of Science, Engineering & Technology, Swinburne University of Technology, Melbourne, Victoria, Australia
| | - Kevin George
- Department of Chemical Engineering, Indian Institute of Technology Hyderabad, Sangareddy, Telangana, India
| | - Suman Gare
- Department of Chemical Engineering, Indian Institute of Technology Hyderabad, Sangareddy, Telangana, India
| | - K V Venkatesh
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai, Maharashtra, India
| | - Kishalay Mitra
- Department of Chemical Engineering, Indian Institute of Technology Hyderabad, Sangareddy, Telangana, India
| | - Lopamudra Giri
- Department of Chemical Engineering, Indian Institute of Technology Hyderabad, Sangareddy, Telangana, India
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6
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Bogaj K, Kaplon R, Urban-Ciecko J. GABAAR-mediated tonic inhibition differentially modulates intrinsic excitability of VIP- and SST- expressing interneurons in layers 2/3 of the somatosensory cortex. Front Cell Neurosci 2023; 17:1270219. [PMID: 37900589 PMCID: PMC10602639 DOI: 10.3389/fncel.2023.1270219] [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: 07/31/2023] [Accepted: 09/25/2023] [Indexed: 10/31/2023] Open
Abstract
Extrasynaptic GABAA receptors (GABAARs) mediating tonic inhibition are thought to play an important role in the regulation of neuronal excitability. However, little is known about a cell type-specific tonic inhibition in molecularly distinctive types of GABAergic interneurons in the mammalian neocortex. Here, we used whole-cell patch-clamp techniques in brain slices prepared from transgenic mice expressing red fluorescent protein (TdTomato) in vasoactive intestinal polypeptide- or somatostatin- positive interneurons (VIP-INs and SST-INs, respectively) to investigate tonic and phasic GABAAR-mediated inhibition as well as effects of GABAA inhibition on intrinsic excitability of these interneurons in layers 2/3 (L2/3) of the somatosensory (barrel) cortex. We found that tonic inhibition was stronger in VIP-INs compared to SST-INs. Contrary to the literature data, tonic inhibition in SST-INs was comparable to pyramidal (Pyr) neurons. Next, tonic inhibition in both interneuron types was dependent on the activity of delta subunit-containing GABAARs. Finally, the GABAAR activity decreased intrinsic excitability of VIP-INs but not SST-INs. Altogether, our data indicate that GABAAR-mediated inhibition modulates neocortical interneurons in a type-specific manner. In contrast to L2/3 VIP-INs, intrinsic excitability of L2/3 SST-INs is immune to the GABAAR-mediated inhibition.
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Affiliation(s)
| | | | - Joanna Urban-Ciecko
- Laboratory of Electrophysiology, Nencki Institute of Experimental Biology, Warsaw, Poland
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7
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Pedraza N, Monserrat MV, Ferrezuelo F, Torres-Rosell J, Colomina N, Miguez-Cabello F, Párraga JP, Soto D, López-Merino E, García-Vilela C, Esteban JA, Egea J, Garí E. Cyclin D1-Cdk4 regulates neuronal activity through phosphorylation of GABAA receptors. Cell Mol Life Sci 2023; 80:280. [PMID: 37684532 PMCID: PMC10491536 DOI: 10.1007/s00018-023-04920-7] [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: 06/14/2023] [Revised: 08/10/2023] [Accepted: 08/12/2023] [Indexed: 09/10/2023]
Abstract
Nuclear Cyclin D1 (Ccnd1) is a main regulator of cell cycle progression and cell proliferation. Interestingly, Ccnd1 moves to the cytoplasm at the onset of differentiation in neuronal precursors. However, cytoplasmic functions and targets of Ccnd1 in post-mitotic neurons are unknown. Here we identify the α4 subunit of gamma-aminobutyric acid (GABA) type A receptors (GABAARs) as an interactor and target of Ccnd1-Cdk4. Ccnd1 binds to an intracellular loop in α4 and, together with Cdk4, phosphorylates the α4 subunit at threonine 423 and serine 431. These modifications upregulate α4 surface levels, increasing the response of α4-containing GABAARs, measured in whole-cell patch-clamp recordings. In agreement with this role of Ccnd1-Cdk4 in neuronal signalling, inhibition of Cdk4 or expression of the non-phosphorylatable α4 decreases synaptic and extra-synaptic currents in the hippocampus of newborn rats. Moreover, according to α4 functions in synaptic pruning, CCND1 knockout mice display an altered pattern of dendritic spines that is rescued by the phosphomimetic α4. Overall, our findings molecularly link Ccnd1-Cdk4 to GABAARs activity in the central nervous system and highlight a novel role for this G1 cyclin in neuronal signalling.
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Affiliation(s)
- Neus Pedraza
- Cell Cycle, Department of Basic Medical Sciences, Institut de Recerca Biomèdica de Lleida (IRBLLEIDA), University of Lleida, Lleida, Spain.
| | - Ma Ventura Monserrat
- Cell Cycle, Department of Basic Medical Sciences, Institut de Recerca Biomèdica de Lleida (IRBLLEIDA), University of Lleida, Lleida, Spain
| | - Francisco Ferrezuelo
- Cell Cycle, Department of Basic Medical Sciences, Institut de Recerca Biomèdica de Lleida (IRBLLEIDA), University of Lleida, Lleida, Spain
| | - Jordi Torres-Rosell
- Cell Cycle, Department of Basic Medical Sciences, Institut de Recerca Biomèdica de Lleida (IRBLLEIDA), University of Lleida, Lleida, Spain
| | - Neus Colomina
- Cell Cycle, Department of Basic Medical Sciences, Institut de Recerca Biomèdica de Lleida (IRBLLEIDA), University of Lleida, Lleida, Spain
| | - Federico Miguez-Cabello
- Laboratori de Neurofisiologia, Departament de Biomedicina, Facultat de Medicina i Ciències de la Salut, Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain
- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Hospital Clínic, Universitat de Barcelona, Barcelona, Spain
| | - Javier Picañol Párraga
- Laboratori de Neurofisiologia, Departament de Biomedicina, Facultat de Medicina i Ciències de la Salut, Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain
- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Hospital Clínic, Universitat de Barcelona, Barcelona, Spain
| | - David Soto
- Laboratori de Neurofisiologia, Departament de Biomedicina, Facultat de Medicina i Ciències de la Salut, Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain
- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Hospital Clínic, Universitat de Barcelona, Barcelona, Spain
| | - Esperanza López-Merino
- Department of Molecular Neurobiology, Centro de Biología Molecular 'Severo Ochoa', Consejo Superior de Investigaciones Científicas (CSIC)/Universidad Autónoma de Madrid (UAM), Madrid, Spain
| | - Celia García-Vilela
- Department of Molecular Neurobiology, Centro de Biología Molecular 'Severo Ochoa', Consejo Superior de Investigaciones Científicas (CSIC)/Universidad Autónoma de Madrid (UAM), Madrid, Spain
| | - José A Esteban
- Department of Molecular Neurobiology, Centro de Biología Molecular 'Severo Ochoa', Consejo Superior de Investigaciones Científicas (CSIC)/Universidad Autónoma de Madrid (UAM), Madrid, Spain
| | - Joaquim Egea
- Molecular and Developmental Neurobiology, Dept. Ciències Mèdiques Bàsiques, Facultat de Medicina, Universitat de Lleida/IRBLLEIDA, Rovira Roure 80, 25198, Lleida, Spain
| | - Eloi Garí
- Cell Cycle, Department of Basic Medical Sciences, Institut de Recerca Biomèdica de Lleida (IRBLLEIDA), University of Lleida, Lleida, Spain.
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8
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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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9
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Seabrook LT, Naef L, Baimel C, Judge AK, Kenney T, Ellis M, Tayyab T, Armstrong M, Qiao M, Floresco SB, Borgland SL. Disinhibition of the orbitofrontal cortex biases decision-making in obesity. Nat Neurosci 2023; 26:92-106. [PMID: 36522498 DOI: 10.1038/s41593-022-01210-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 10/21/2022] [Indexed: 12/23/2022]
Abstract
The lateral orbitofrontal cortex (lOFC) receives sensory information about food and integrates these signals with expected outcomes to guide future actions, and thus may play a key role in a distributed network of neural circuits that regulate feeding behavior. Here, we reveal a new role for the lOFC in the cognitive control of behavior in obesity. Food-seeking behavior is biased in obesity such that in male obese mice, behaviors are less flexible to changes in the perceived value of the outcome. Obesity is associated with reduced lOFC inhibitory drive and chemogenetic reduction in GABAergic neurotransmission in the lOFC induces obesity-like impairments in goal-directed behavior. Conversely, pharmacological or optogenetic restoration of inhibitory neurotransmission in the lOFC of obese mice reinstates flexible behavior. Our results indicate that obesity-induced disinhibition of the lOFC leads to a failure to update changes in the value of food with satiety, which in turn may influence how individuals make decisions in an obesogenic environment.
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Affiliation(s)
- Lauren T Seabrook
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, The University of Calgary, Calgary, Alberta, Canada
| | - Lindsay Naef
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, The University of Calgary, Calgary, Alberta, Canada
| | - Corey Baimel
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, The University of Calgary, Calgary, Alberta, Canada
| | - Allap K Judge
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, The University of Calgary, Calgary, Alberta, Canada
| | - Tyra Kenney
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, The University of Calgary, Calgary, Alberta, Canada
| | - Madelyn Ellis
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, The University of Calgary, Calgary, Alberta, Canada
| | - Temoor Tayyab
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, The University of Calgary, Calgary, Alberta, Canada
| | - Mataea Armstrong
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, The University of Calgary, Calgary, Alberta, Canada
| | - Min Qiao
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, The University of Calgary, Calgary, Alberta, Canada
| | - Stan B Floresco
- Department of Psychology, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Stephanie L Borgland
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, The University of Calgary, Calgary, Alberta, Canada.
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10
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Goisis RC, Chiavegato A, Gomez-Gonzalo M, Marcon I, Requie LM, Scholze P, Carmignoto G, Losi G. GABA tonic currents and glial cells are altered during epileptogenesis in a mouse model of Dravet syndrome. Front Cell Neurosci 2022; 16:919493. [PMID: 35936501 PMCID: PMC9350930 DOI: 10.3389/fncel.2022.919493] [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: 04/13/2022] [Accepted: 06/28/2022] [Indexed: 11/17/2022] Open
Abstract
Dravet Syndrome (DS) is a rare autosomic encephalopathy with epilepsy linked to Nav1.1 channel mutations and defective GABAergic signaling. Effective therapies for this syndrome are lacking, urging a better comprehension of the mechanisms involved. In a recognized mouse model of DS, we studied GABA tonic current, a form of inhibition largely neglected in DS, in brain slices from developing mice before spontaneous seizures are reported. In neurons from the temporal cortex (TeCx) and CA1 region, GABA tonic current was reduced in DS mice compared to controls, while in the entorhinal cortex (ECx) it was not affected. In this region however allopregnanonole potentiation of GABA tonic current was reduced in DS mice, suggesting altered extrasynaptic GABAA subunits. Using THIP as a selective agonist, we found reduced δ subunit mediated tonic currents in ECx of DS mice. Unexpectedly in the dentate gyrus (DG), a region with high δ subunit expression, THIP-evoked currents in DS mice were larger than in controls. An immunofluorescence study confirmed that δ subunit expression was reduced in ECx and increased in DG of DS mice. Finally, considering the importance of neuroinflammation in epilepsy and neurodevelopmental disorders, we evaluated classical markers of glia activation. Our results show that DS mice have increased Iba1 reactivity and GFAP expression in both ECx and DG, compared to controls. Altogether we report that before spontaneous seizures, DS mice develop significant alterations of GABA tonic currents and glial cell activation. Understanding all the mechanisms involved in these alterations during disease maturation and progression may unveil new therapeutic targets.
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Affiliation(s)
- Rosa Chiara Goisis
- Department of Biomedical Science, University of Padua, Padua, Italy
- Neuroscience Institute, National Research Council (IN-CNR), Padua, Italy
| | - Angela Chiavegato
- Neuroscience Institute, National Research Council (IN-CNR), Padua, Italy
| | - Marta Gomez-Gonzalo
- Department of Biomedical Science, University of Padua, Padua, Italy
- Neuroscience Institute, National Research Council (IN-CNR), Padua, Italy
| | - Iacopo Marcon
- Department of Biomedical Science, University of Padua, Padua, Italy
| | | | - Petra Scholze
- Department of Pathobiology of the Nervous System, Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Giorgio Carmignoto
- Department of Biomedical Science, University of Padua, Padua, Italy
- Neuroscience Institute, National Research Council (IN-CNR), Padua, Italy
| | - Gabriele Losi
- Department of Biomedical Science, University of Padua, Padua, Italy
- Neuroscience Institute, National Research Council (IN-CNR), Padua, Italy
- *Correspondence: Gabriele Losi
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11
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Uygun DS, Basheer R. Circuits and components of delta wave regulation. Brain Res Bull 2022; 188:223-232. [PMID: 35738502 DOI: 10.1016/j.brainresbull.2022.06.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 06/07/2022] [Accepted: 06/14/2022] [Indexed: 11/02/2022]
Abstract
Sleep is vital and the deepest stages of sleep occur within Non-rapid-eye-movement sleep (NREM), defined by high electroencephalographic power in the delta (~0.5-4Hz) wave frequency range. Delta waves are thought to facilitate a myriad of physical and mental health functions. This review aims to comprehensively cover the historical and recent advances in the understanding of the mechanisms orchestrating NREM delta waves. We discuss a complete neurocircuit - focusing on one leg of the circuit at a time - and delve deeply into the molecular mechanistic components that contribute to NREM delta wave regulation. We also discuss the relatively localized nature in which these mechanisms have been defined, and how likely they might generalize across distinct sensory and higher order modalities in the brain.
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Affiliation(s)
- David S Uygun
- VA Boston Healthcare System and Harvard Medical School, Dept. of Psychiatry, West Roxbury, MA; 02132.
| | - Radhika Basheer
- VA Boston Healthcare System and Harvard Medical School, Dept. of Psychiatry, West Roxbury, MA; 02132.
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12
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Kaplanian A, Vinos M, Skaliora I. GABAb- and GABAa- mediated regulation of Up and Down states across development. J Physiol 2022; 600:2401-2427. [PMID: 35365894 DOI: 10.1113/jp282736] [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: 12/15/2021] [Accepted: 03/18/2022] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Slow oscillations (SOs), the EEG hallmark of non-REM sleep, and their cellular counterpart, Up-and-Down states (UDSs), are considered the default activity of the cerebral cortex and reflect the underlying neural connectivity. GABAb- and GABAa- receptor-mediated inhibition play a major role in regulating UDS activity. Although SOs and UDSs exhibit significant alterations as a function of age, it is unknown how developmental changes in inhibition contribute to the developmental profile of this activity. In this study, we reveal for the first time, age-dependent effects of GABAb and GABAa signalling on UDSs. We also document the differential subunit composition of postsynaptic GABAa receptors in young and adult animals, highlighting the α1-subunit as a major component of the age-differentiated regulation of UDSs. These findings help clarify the mechanisms that underlie the maturation of cortical network activity, and enhance our understanding regarding the emergence of neurodevelopmental disorders. ABSTRACT Slow oscillations, the hallmark of non-REM sleep, and their cellular counterpart, Up-and-Down states (UDSs), are considered a signature of cortical dynamics that reflect the intrinsic network organization. Although previous studies have explored the role of inhibition in regulating UDSs, little is known about whether this role changes with maturation. This is surprising since both slow oscillations and UDSs exhibit significant age-dependent alterations. To elucidate the developmental impact of GABAb and GABAa receptors on UDS activity, we conducted simultaneous LFP and intracellular recordings ex vivo, in brain slices of young and adult male mice, using selective blockers, CGP and non-saturating concentration of gabazine, respectively. Blockade of both GABAb- and GABAa- signalling showed age-differentiated functions. CGP caused an increase in Down state duration in young animals, but a decrease in adults. Gabazine evoked Spike-and-Wave-Discharges in both ages; however, while young networks became completely epileptic, adults maintained the ability to generate UDSs. Furthermore, voltage clamp recordings of mIPSCs revealed that gabazine selectively blocks phasic currents, particularly involving postsynaptic mechanisms. The latter exhibit clear maturational changes, suggesting a different subunit composition of GABAa receptors in young vs. adult animals. Indeed, subsequent LFP recordings under diazepam (nanomolar or micromolar concentrations) revealed that mechanisms engaging the drug's classical-binding-site, mediated by α1-subunit containing GABAa receptors, have a bigger contribution in Up state initiation in young networks compared to adults. Taken together, these findings help clarify the mechanisms that underlie the maturation of cortical network activity and enhance our understanding regarding the emergence of neurodevelopmental disorders. Abstract figure legend GABAb receptors' participation in Up state termination mechanisms is well-conserved across development. However, regulation of Down-to-Up transitions is age-dependent; GABAb receptors promote them in young while preventing them in adults. Up state maintenance is determined by age-dependent synaptic GABAa receptors' subunit composition and kinetics; α1-GABAa receptors dominate in young while non-α1-GABAa receptors dominate in adults. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Ani Kaplanian
- Center for Basic Research, Biomedical Research Foundation of Academy of Athens (BRFAA), Athens, 11527, Greece.,Department of Biology, University of Patras, Rio, 26504, Greece
| | - Michael Vinos
- Center for Basic Research, Biomedical Research Foundation of Academy of Athens (BRFAA), Athens, 11527, Greece.,Department of History and Philosophy of Science, University of Athens, Athens, 15771, Greece
| | - Irini Skaliora
- Center for Basic Research, Biomedical Research Foundation of Academy of Athens (BRFAA), Athens, 11527, Greece.,Department of History and Philosophy of Science, University of Athens, Athens, 15771, Greece
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13
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Paulsen RT, Burrell BD. Activity-Dependent Modulation of Tonic GABA Currents by Endocannabinoids in Hirudo verbana. Front Synaptic Neurosci 2022; 14:760330. [PMID: 35368247 PMCID: PMC8964407 DOI: 10.3389/fnsyn.2022.760330] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 02/21/2022] [Indexed: 01/21/2023] Open
Abstract
Endocannabinoids are lipid neuromodulators that are synthesized on demand and primarily signal in a retrograde manner to elicit depression of excitatory and inhibitory synapses. Despite the considerable interest in their potential analgesic effects, there is evidence that endocannabinoids can have both pro-nociceptive and anti-nociceptive effects. The mechanisms contributing to the opposing effects of endocannabinoids in nociception need to be better understood before cannabinoid-based therapies can be effectively utilized to treat pain. Using the medicinal leech, Hirudo verbana, this work investigates whether endocannabinoids modulate tonic inhibition onto non-nociceptive afferents. In voltage clamp recordings, we analyzed changes in the tonic inhibition in pressure-sensitive (P) cells following pre-treatment with endocannabinoids, 2-arachidonoylglycerol (2-AG) or anandamide (AEA). We also tested whether high frequency stimulation (HFS) of nociceptive (N) cells could also modulate tonic inhibition. Both endocannabinoid application and N cell HFS depressed tonic inhibition in the P cell. Depression of tonic inhibition by N cell HFS was blocked by SB 366791 (a TRPV1 inhibitor). SB 366791 also prevented 2-AG-and AEA-induced depression of tonic inhibition. HFS-induced depression was not blocked by tetrahydrolipstatin (THL), which prevents 2-AG synthesis, nor AM 251 (a CB1 receptor inverse agonist). These results illustrate a novel activity-dependent modulation of tonic GABA currents that is mediated by endocannabinoid signaling and is likely to play an important role in sensitization of non-nociceptive afferent pathways.
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14
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Beltrán-Matas P, Castilho Á, Tencer B, Veruki ML, Hartveit E. Inhibitory inputs to an inhibitory interneuron: Spontaneous postsynaptic currents and GABA A receptors of A17 amacrine cells in the rat retina. Eur J Neurosci 2022; 55:1442-1470. [PMID: 35236011 PMCID: PMC9314042 DOI: 10.1111/ejn.15634] [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: 09/23/2021] [Revised: 02/25/2022] [Accepted: 02/26/2022] [Indexed: 11/29/2022]
Abstract
Amacrine cells constitute a large and heterogenous group of inhibitory interneurons in the retina. The A17 amacrine plays an important role for visual signaling in the rod pathway microcircuit of the mammalian retina. It receives excitatory input from rod bipolar cells and provides feedback inhibition to the same cells. However, from ultrastructural investigations, there is evidence for input to A17s from other types of amacrine cells, presumably inhibitory, but there is a lack of information about the identity and functional properties of the synaptic receptors and how inhibition contributes to the integrative properties of A17s. Here, we studied the biophysical and pharmacological properties of GABAergic spontaneous inhibitory postsynaptic currents (spIPSCs) and GABAA receptors of A17 amacrines, using whole-cell and outside-out patch recordings from rat retinal slices. The spIPSCs displayed fast onsets (10-90% rise time ~740 μs) and double-exponential decays (τfast ~4.5 ms [43% of amplitude]; τslow ~22 ms). Ultrafast application of brief pulses of GABA (3 mM) to patches evoked responses with deactivation kinetics best fitted by a triple-exponential function (τ1 ~5.3 ms [55% of amplitude]; τ2 ~48 ms [32% amplitude]; τ3 ~187 ms). Non-stationary noise analysis of spIPSCs and patch responses yielded single-channel conductances of ~21 and ~25 pS, respectively. Pharmacological analysis suggested that the spIPSCs are mediated by receptors with an α1βγ2 subunit composition and the somatic receptors have an α2βγ2 and/or α3βγ2 composition. These results demonstrate the presence of synaptic GABAA receptors on A17s, which may play an important role in signal integration in these cells.
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Affiliation(s)
| | - Áurea Castilho
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Barbora Tencer
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | | | - Espen Hartveit
- Department of Biomedicine, University of Bergen, Bergen, Norway
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15
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Yao HK, Guet-McCreight A, Mazza F, Moradi Chameh H, Prevot TD, Griffiths JD, Tripathy SJ, Valiante TA, Sibille E, Hay E. Reduced inhibition in depression impairs stimulus processing in human cortical microcircuits. Cell Rep 2022; 38:110232. [PMID: 35021088 DOI: 10.1016/j.celrep.2021.110232] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 10/07/2021] [Accepted: 12/16/2021] [Indexed: 12/01/2022] Open
Abstract
Cortical processing depends on finely tuned excitatory and inhibitory connections in neuronal microcircuits. Reduced inhibition by somatostatin-expressing interneurons is a key component of altered inhibition associated with treatment-resistant major depressive disorder (depression), which is implicated in cognitive deficits and rumination, but the link remains to be better established mechanistically in humans. Here we test the effect of reduced somatostatin interneuron-mediated inhibition on cortical processing in human neuronal microcircuits using a data-driven computational approach. We integrate human cellular, circuit, and gene expression data to generate detailed models of human cortical microcircuits in health and depression. We simulate microcircuit baseline and response activity and find a reduced signal-to-noise ratio and increased false/failed detection of stimuli due to a higher baseline activity in depression. We thus apply models of human cortical microcircuits to demonstrate mechanistically how reduced inhibition impairs cortical processing in depression, providing quantitative links between altered inhibition and cognitive deficits.
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Affiliation(s)
- Heng Kang Yao
- Krembil Centre for Neuroinformatics, Centre for Addiction and Mental Health, Toronto, ON M5T 1R7, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A1, Canada
| | - Alexandre Guet-McCreight
- Krembil Centre for Neuroinformatics, Centre for Addiction and Mental Health, Toronto, ON M5T 1R7, Canada
| | - Frank Mazza
- Krembil Centre for Neuroinformatics, Centre for Addiction and Mental Health, Toronto, ON M5T 1R7, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A1, Canada
| | | | - Thomas D Prevot
- Department of Psychiatry, University of Toronto, Toronto, ON M5S 1A1, Canada; Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON M5T 1R7, Canada
| | - John D Griffiths
- Krembil Centre for Neuroinformatics, Centre for Addiction and Mental Health, Toronto, ON M5T 1R7, Canada; Department of Psychiatry, University of Toronto, Toronto, ON M5S 1A1, Canada; Institute of Medical Sciences, University of Toronto, Toronto, ON M5S 1A1, Canada
| | - Shreejoy J Tripathy
- Krembil Centre for Neuroinformatics, Centre for Addiction and Mental Health, Toronto, ON M5T 1R7, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A1, Canada; Department of Psychiatry, University of Toronto, Toronto, ON M5S 1A1, Canada; Institute of Medical Sciences, University of Toronto, Toronto, ON M5S 1A1, Canada
| | - Taufik A Valiante
- Krembil Research Institute, University Health Network, Toronto, ON M5T 0S8, Canada; Institute of Medical Sciences, University of Toronto, Toronto, ON M5S 1A1, Canada; Department of Electrical and Computer Engineering, University of Toronto, Toronto, ON M5S 1A1; Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON M5S 1A1, Canada; Department of Surgery, University of Toronto, Toronto, ON M5S 1A1, Canada; Max Planck-University of Toronto Center for Neural Science and Technology, University of Toronto, Toronto, ON M5S 1A1, Canada; Center for Advancing Neurotechnological Innovation to Application, University of Toronto, Toronto, ON M5S 1A1, Canada
| | - Etienne Sibille
- Department of Psychiatry, University of Toronto, Toronto, ON M5S 1A1, Canada; Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON M5T 1R7, Canada; Department of Pharmacology & Toxicology, University of Toronto, Toronto, ON M5S 1A1, Canada
| | - Etay Hay
- Krembil Centre for Neuroinformatics, Centre for Addiction and Mental Health, Toronto, ON M5T 1R7, Canada; Department of Physiology, University of Toronto, Toronto, ON M5S 1A1, Canada; Department of Psychiatry, University of Toronto, Toronto, ON M5S 1A1, Canada.
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16
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Kwon J, Jang MW, Lee CJ. Retina-attached slice recording reveals light-triggered tonic GABA signaling in suprachiasmatic nucleus. Mol Brain 2021; 14:171. [PMID: 34838118 PMCID: PMC8626980 DOI: 10.1186/s13041-021-00881-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 11/14/2021] [Indexed: 11/10/2022] Open
Abstract
Light is a powerful external cue modulating the biological rhythm of internal clock neurons in the suprachiasmatic nucleus (SCN). GABA signaling in SCN is critically involved in this process. Both phasic and tonic modes of GABA signaling exist in SCN. Of the two modes, the tonic mode of GABA signaling has been implicated in light-mediated synchrony of SCN neurons. However, modulatory effects of external light on tonic GABA signalling are yet to be explored. Here, we systematically characterized electrophysiological properties of the clock neurons and determined the spatio-temporal profiles of tonic GABA current. Based on the whole-cell patch-clamp recordings from 76 SCN neurons, the cells with large tonic GABA current (>15 pA) were more frequently found in dorsal SCN. Moreover, tonic GABA current in SCN was highly correlated with the frequency of spontaneous inhibitory postsynaptic current (sIPSC), raising a possibility that tonic GABA current is due to spill-over from synaptic release. Interestingly, tonic GABA current was inversely correlated with slice-to-patch time interval, suggesting a critical role of retinal light exposure in intact brain for an induction of tonic GABA current in SCN. To test this possibility, we obtained meticulously prepared retina-attached SCN slices and successfully recorded tonic and phasic GABA signaling in SCN neurons. For the first time, we observed an early-onset, long-lasting tonic GABA current, followed by a slow-onset, short-lasting increase in the phasic GABA frequency, upon direct light-illumination of the attached retina. This result provides the first evidence that external light cue can directly trigger both tonic and phasic GABA signaling in SCN cell. In conclusion, we propose tonic GABA as the key mediator of external light in SCN.
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Affiliation(s)
- Jea Kwon
- KU-KIST Graduate School of Converging Science and Technology, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea.,Center for Cognition and Sociality, Institute for Basic Science (IBS), 55 Expo-ro, Yusung-gu, 34126, Daejeon, Republic of Korea
| | - Minwoo Wendy Jang
- KU-KIST Graduate School of Converging Science and Technology, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea.,Center for Cognition and Sociality, Institute for Basic Science (IBS), 55 Expo-ro, Yusung-gu, 34126, Daejeon, Republic of Korea
| | - C Justin Lee
- KU-KIST Graduate School of Converging Science and Technology, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea. .,Center for Cognition and Sociality, Institute for Basic Science (IBS), 55 Expo-ro, Yusung-gu, 34126, Daejeon, Republic of Korea.
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17
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Field M, Lukacs IP, Hunter E, Stacey R, Plaha P, Livermore L, Ansorge O, Somogyi P. 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] [MESH Headings] [Grants] [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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Affiliation(s)
- Martin Field
- Department of Pharmacology, University of Oxford, Oxford OX1 3QT, United Kingdom
| | - Istvan P Lukacs
- Department of Pharmacology, University of Oxford, Oxford OX1 3QT, United Kingdom
| | - Emily Hunter
- Department of Pharmacology, University of Oxford, Oxford OX1 3QT, United Kingdom
| | - Richard Stacey
- Department of Neurosurgery, John Radcliffe Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford OX3 9DU, United Kingdom
| | - Puneet Plaha
- Department of Neurosurgery, John Radcliffe Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford OX3 9DU, United Kingdom
| | - Laurent Livermore
- Department of Neurosurgery, John Radcliffe Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford OX3 9DU, United Kingdom
| | - Olaf Ansorge
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, United Kingdom
| | - Peter Somogyi
- Department of Pharmacology, University of Oxford, Oxford OX1 3QT, United Kingdom
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18
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Wyroślak M, Lebida K, Mozrzymas JW. Induction of Inhibitory Synaptic Plasticity Enhances Tonic Current by Increasing the Content of α5-Subunit Containing GABA A Receptors in Hippocampal Pyramidal Neurons. Neuroscience 2021; 467:39-46. [PMID: 34033868 DOI: 10.1016/j.neuroscience.2021.05.020] [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: 03/24/2021] [Revised: 05/14/2021] [Accepted: 05/17/2021] [Indexed: 11/16/2022]
Abstract
It is known that besides synaptic inhibition, there is a persistent component of inhibitory drive mediated by tonic currents which is believed to mediate majority of the total inhibitory charge in hippocampal neurons. Tonic currents, depending on cell types, can be mediated by a variety of GABAA receptor (GABAAR) subtypes but in pyramidal neurons, α5-subunit containing receptors were found to be predominant. Importantly, α5-GABAARs were implicated in both inhibitory and excitatory synaptic plasticity as well as in a variety of cognitive tasks. In the present study, we asked whether the protocol that evokes NMDAR-dependent GABAergic inhibitory long-term potentiation (iLTP) also induces the plasticity of tonic inhibition in hippocampal pyramidal neurons. Our whole-cell patch-clamp recordings revealed that the induction of this type of iLTP is associated with a marked increase in tonic current. By using the specific inverse agonist of α5-containing GABAARs (L-655,709) we provide evidence that this plastic change in tonic current is correlated with an increased proportion of this type of GABAARs. On the contrary, the iLTP induction did not affect the tonic current potentiated by THIP, indicating that the pool of δ subunit-containing GABAARs receptors remains unaffected. We conclude that the α5-GABAARs-dependent plasticity of tonic inhibition is a novel dimension of the neuroplasticity of the inhibitory drive in the hippocampal principal neurons. Overall, α5-containing GABAARs emerge as key players in a variety of plasticity mechanisms operating over a large span of time and spatial scales.
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Affiliation(s)
- Marcin Wyroślak
- Department of Biophysics and Neuroscience, Wroclaw Medical University, 50-367 Wroclaw, Poland.
| | - Katarzyna Lebida
- Department of Biophysics and Neuroscience, Wroclaw Medical University, 50-367 Wroclaw, Poland
| | - Jerzy W Mozrzymas
- Department of Biophysics and Neuroscience, Wroclaw Medical University, 50-367 Wroclaw, Poland
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19
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Wu K, Han W, Tian Q, Li Y, Lu W. Activity- and sleep-dependent regulation of tonic inhibition by Shisa7. Cell Rep 2021; 34:108899. [PMID: 33761345 PMCID: PMC8025742 DOI: 10.1016/j.celrep.2021.108899] [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: 08/19/2020] [Revised: 12/22/2020] [Accepted: 03/03/2021] [Indexed: 02/08/2023] Open
Abstract
Tonic inhibition mediated by extrasynaptic γ-aminobutyric acid type A receptors (GABAARs) critically regulates neuronal excitability and brain function. However, the mechanisms regulating tonic inhibition remain poorly understood. Here, we report that Shisa7 is critical for tonic inhibition regulation in hippocampal neurons. In juvenile Shisa7 knockout (KO) mice, α5-GABAAR-mediated tonic currents are significantly reduced. Mechanistically, Shisa7 is crucial for α5-GABAAR exocytosis. Additionally, Shisa7 regulation of tonic inhibition requires protein kinase A (PKA) that phosphorylates Shisa7 serine 405 (S405). Importantly, tonic inhibition undergoes activity-dependent regulation, and Shisa7 is required for homeostatic potentiation of tonic inhibition. Interestingly, in young adult Shisa7 KOs, basal tonic inhibition in hippocampal neurons is unaltered, largely due to the diminished α5-GABAAR component of tonic inhibition. However, at this stage, tonic inhibition oscillates during the daily sleep/wake cycle, a process requiring Shisa7. Together, these data demonstrate that intricate signaling mechanisms regulate tonic inhibition at different developmental stages and reveal a molecular link between sleep and tonic inhibition.
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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
| | - 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
| | - Yan Li
- Proteomics Core Facility, National Institute of Neurological Disorders and Stroke, 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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20
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Pléau C, Peret A, Pearlstein E, Scalfati T, Vigier A, Marti G, Michel FJ, Marissal T, Crépel V. Dentate Granule Cells Recruited in the Home Environment Display Distinctive Properties. Front Cell Neurosci 2021; 14:609123. [PMID: 33519383 PMCID: PMC7843370 DOI: 10.3389/fncel.2020.609123] [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: 09/22/2020] [Accepted: 12/23/2020] [Indexed: 11/13/2022] Open
Abstract
The dentate granule cells (DGCs) play a crucial role in learning and memory. Many studies have described the role and physiological properties of these sparsely active neurons using different behavioral contexts. However, the morpho-functional features of DGCs recruited in mice maintained in their home cage (without training), considered as a baseline condition, have not yet been established. Using fosGFP transgenic mice, we observed ex vivo that DGCs recruited in animals maintained in the home cage condition are mature neurons that display a longer dendritic tree and lower excitability compared with non-activated cells. The higher GABAA receptor-mediated shunting inhibition contributes to the lower excitability of DGCs activated in the home environment by shifting the input resistance towards lower values. Remarkably, that shunting inhibition is neither observed in non-activated DGCs nor in DGCs activated during training in virtual reality. In short, our results suggest that strong shunting inhibition and reduced excitability could constitute a distinctive neural signature of mature DGCs recruited in the context of the home environment.
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Affiliation(s)
- Claire Pléau
- INMED, INSERM UMR1249, Aix-Marseille University, Marseille, France
| | - Angélique Peret
- INMED, INSERM UMR1249, Aix-Marseille University, Marseille, France
| | | | - Thomas Scalfati
- INMED, INSERM UMR1249, Aix-Marseille University, Marseille, France
| | - Alexandre Vigier
- INMED, INSERM UMR1249, Aix-Marseille University, Marseille, France
| | | | | | - Thomas Marissal
- INMED, INSERM UMR1249, Aix-Marseille University, Marseille, France
| | - Valérie Crépel
- INMED, INSERM UMR1249, Aix-Marseille University, Marseille, France
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21
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Davenport CM, Rajappa R, Katchan L, Taylor CR, Tsai MC, Smith CM, de Jong JW, Arnold DB, Lammel S, Kramer RH. Relocation of an Extrasynaptic GABA A Receptor to Inhibitory Synapses Freezes Excitatory Synaptic Strength and Preserves Memory. Neuron 2021; 109:123-134.e4. [PMID: 33096025 PMCID: PMC7790995 DOI: 10.1016/j.neuron.2020.09.037] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 08/21/2020] [Accepted: 09/25/2020] [Indexed: 11/27/2022]
Abstract
The excitatory synapse between hippocampal CA3 and CA1 pyramidal neurons exhibits long-term potentiation (LTP), a positive feedback process implicated in learning and memory in which postsynaptic depolarization strengthens synapses, promoting further depolarization. Without mechanisms for interrupting positive feedback, excitatory synapses could strengthen inexorably, corrupting memory storage. Here, we reveal a hidden form of inhibitory synaptic plasticity that prevents accumulation of excitatory LTP. We developed a knockin mouse that allows optical control of endogenous α5-subunit-containing γ-aminobutyric acid (GABA)A receptors (α5-GABARs). Induction of excitatory LTP relocates α5-GABARs, which are ordinarily extrasynaptic, to inhibitory synapses, quashing further NMDA receptor activation necessary for inducing more excitatory LTP. Blockade of α5-GABARs accelerates reversal learning, a behavioral test for cognitive flexibility dependent on repeated LTP. Hence, inhibitory synaptic plasticity occurs in parallel with excitatory synaptic plasticity, with the ensuing interruption of the positive feedback cycle of LTP serving as a possible critical early step in preserving memory.
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Affiliation(s)
- Christopher M Davenport
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Rajit Rajappa
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Ljudmila Katchan
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Charlotte R Taylor
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Ming-Chi Tsai
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Caleb M Smith
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Johannes W de Jong
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Don B Arnold
- Department of Biology, Section of Molecular and Computational Biology, University of Southern California, Los Angeles, Los Angeles, CA 90089, USA
| | - Stephan Lammel
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Richard H Kramer
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA.
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22
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Manzo MA, Wang DS, Li WW, Pinguelo A, Popa MO, Khodaei S, Atack JR, Ross RA, Orser BA. Inhibition of a tonic inhibitory conductance in mouse hippocampal neurones by negative allosteric modulators of α5 subunit-containing γ-aminobutyric acid type A receptors: implications for treating cognitive deficits. Br J Anaesth 2020; 126:674-683. [PMID: 33388140 DOI: 10.1016/j.bja.2020.11.032] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 10/30/2020] [Accepted: 11/16/2020] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Multiple cognitive and psychiatric disorders are associated with an increased tonic inhibitory conductance that is generated by α5 subunit-containing γ-aminobutyric acid type A (α5 GABAA) receptors. Negative allosteric modulators that inhibit α5 GABAA receptors (α5-NAMs) are being developed as treatments for these disorders. The effects of α5-NAMs have been studied on recombinant GABAA receptors expressed in non-neuronal cells; however, no study has compared drug effects on the tonic conductance generated by native GABAA receptors in neurones, which was the goal of this study. METHODS The effects of five α5-NAMs (basmisanil, Ono-160, L-655,708, α5IA, and MRK-016) on tonic current evoked by a low concentration of GABA were studied using whole-cell recordings in cultured mouse hippocampal neurones. Drug effects on current evoked by a saturating concentration of GABA and on miniature inhibitory postsynaptic currents (mIPSCs) were also examined. RESULTS The α5-NAMs caused a concentration-dependent decrease in tonic current. The potencies varied as the inhibitory concentration for 50% inhibition (IC50) of basmisanil (127 nM) was significantly higher than those of the other compounds (0.4-0.8 nM). In contrast, the maximal efficacies of the drugs were similar (35.5-51.3% inhibition). The α5-NAMs did not modify current evoked by a saturating GABA concentration or mIPSCs. CONCLUSIONS Basmisanil was markedly less potent than the other α5-NAMs, an unexpected result based on studies of recombinant α5 GABAA receptors. Studying the effects of α5 GABAA receptor-selective drugs on the tonic inhibitory current in neurones could inform the selection of compounds for future clinical trials.
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Affiliation(s)
- Marc A Manzo
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Dian-Shi Wang
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Winston W Li
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Arsène Pinguelo
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Mariana O Popa
- Medicines Discovery Institute, Cardiff University, Cardiff, Wales
| | - Shahin Khodaei
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - John R Atack
- Medicines Discovery Institute, Cardiff University, Cardiff, Wales
| | - Ruth A Ross
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON, Canada
| | - Beverley A Orser
- Department of Physiology, University of Toronto, Toronto, ON, Canada; Department of Anesthesiology and Pain Medicine, University of Toronto, Toronto, ON, Canada; Department of Anesthesia, Sunnybrook Health Sciences Centre, Toronto, ON, Canada.
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23
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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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24
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Burkhanova G, Chernova K, Khazipov R, Sheroziya M. Effects of Cortical Cooling on Activity Across Layers of the Rat Barrel Cortex. Front Syst Neurosci 2020; 14:52. [PMID: 32848644 PMCID: PMC7417609 DOI: 10.3389/fnsys.2020.00052] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 07/06/2020] [Indexed: 12/25/2022] Open
Abstract
Moderate cortical cooling is known to suppress slow oscillations and to evoke persistent cortical activity. However, the cooling-induced changes in electrical activity across cortical layers remain largely unknown. Here, we performed multi-channel local field potential (LFP) and multi-unit activity (MUA) recordings with linear silicone probes through the layers of single cortical barrel columns in urethane-anesthetized rats under normothermia (38°C) and during local cortical surface cooling (30°C). During cortically generated slow oscillations, moderate cortical cooling decreased delta wave amplitude, delta-wave occurrence, the duration of silent states, and delta wave-locked MUA synchronization. Moderate cortical cooling increased total time spent in the active state and decreased total time spent in the silent state. Cooling-evoked changes in the MUA firing rate in cortical layer 5 (L5) varied from increase to decrease across animals, and the polarity of changes in L5 MUA correlated with changes in total time spent in the active state. The decrease in temperature reduced MUA firing rates in all other cortical layers. Sensory-evoked MUA responses also decreased during cooling through all cortical layers. The cooling-dependent slowdown was detected at the fast time-scale with a decreased frequency of sensory-evoked high-frequency oscillations (HFO). Thus, moderate cortical cooling suppresses slow oscillations and desynchronizes neuronal activity through all cortical layers, and is associated with reduced firing across all cortical layers except L5, where cooling induces variable and non-consistent changes in neuronal firing, which are common features of the transition from slow-wave synchronization to desynchronized activity in the barrel cortex.
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Affiliation(s)
| | - Kseniya Chernova
- Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia
| | - Roustem Khazipov
- Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia.,Aix Marseille University, INSERM, INMED, Marseille, France
| | - Maxim Sheroziya
- Laboratory of Neurobiology, Kazan Federal University, Kazan, Russia
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25
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An Astrocytic Influence on Impaired Tonic Inhibition in Hippocampal CA1 Pyramidal Neurons in a Mouse Model of Rett Syndrome. J Neurosci 2020; 40:6250-6261. [PMID: 32616668 DOI: 10.1523/jneurosci.3042-19.2020] [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: 12/25/2019] [Revised: 05/13/2020] [Accepted: 06/10/2020] [Indexed: 01/28/2023] Open
Abstract
Rett syndrome (RTT) is a severe neurodevelopmental disease caused by mutations in the methyl-CpG binding protein 2 (MECP2) gene. Although altered interneuron development and function are clearly demonstrated in RTT mice, a particular mode of inhibition, tonic inhibition, has not been carefully examined. We report here that tonic inhibition is significantly reduced in pyramidal neurons in the CA1 region of the hippocampus in mice where Mecp2 is deleted either in all cells or specifically in astrocytes. Since no change is detected in the level of GABA receptors, such a reduction in tonic inhibition is likely a result of decreased ambient GABA level in the extracellular space. Consistent with this explanation, we observed increased expression of a GABA transporter, GABA transporter 3 (GAT3), in the hippocampus of the Mecp2 KO mice, as well as a corresponding increase of GAT3 current in hippocampal astrocytes. These phenotypes are relevant to RTT because pharmacological blockage of GAT3 can normalize tonic inhibition and intrinsic excitability in CA1 pyramidal neurons, and rescue the phenotype of increased network excitability in acute hippocampal slices from the Mecp2 KO mice. Finally, chronic administration of a GAT3 antagonist improved a composite symptom score and extended lifespan in the Mecp2 KO mice. Only male mice were used in this study. These results not only advance our understanding of RTT etiology by defining a new neuronal phenotype and revealing how it can be influenced by astrocytic alterations, but also reveal potential targets for intervention.SIGNIFICANCE STATEMENT Our study reports a novel phenotype of reduced tonic inhibition in hippocampal CA1 pyramidal neurons in the Rett syndrome mice, reveal a potential mechanism of increased GABA transporter expression/activity in the neighboring astrocytes, describe a disease-relevant consequence in hyperexcitability, and provide preliminary evidence that targeting this phenotype may slow down disease progression in Rett syndrome mice. These results help our understanding of the disease etiology and identify a new therapeutic target for treating Rett syndrome.
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26
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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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27
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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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28
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Fischer AU, Müller NIC, Deller T, Del Turco D, Fisch JO, Griesemer D, Kattler K, Maraslioglu A, Roemer V, Xu‐Friedman MA, Walter J, Friauf E. GABA is a modulator, rather than a classical transmitter, in the medial nucleus of the trapezoid body-lateral superior olive sound localization circuit. J Physiol 2019; 597:2269-2295. [PMID: 30776090 PMCID: PMC6462465 DOI: 10.1113/jp277566] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 02/18/2019] [Indexed: 12/13/2022] Open
Abstract
KEY POINTS The lateral superior olive (LSO), a brainstem hub involved in sound localization, integrates excitatory and inhibitory inputs from the ipsilateral and the contralateral ear, respectively. In gerbils and rats, inhibition to the LSO reportedly shifts from GABAergic to glycinergic within the first three postnatal weeks. Surprisingly, we found no evidence for synaptic GABA signalling during this time window in mouse LSO principal neurons. However, we found that presynaptic GABAB Rs modulate Ca2+ influx into medial nucleus of the trapezoid body axon terminals, resulting in reduced synaptic strength. Moreover, GABA elicited strong responses in LSO neurons that were mediated by extrasynaptic GABAA Rs. RNA sequencing revealed highly abundant δ subunits, which are characteristic of extrasynaptic receptors. Whereas GABA increased the excitability of neonatal LSO neurons, it reduced the excitability around hearing onset. Collectively, GABA appears to control the excitability of mouse LSO neurons via extrasynaptic and presynaptic signalling. Thus, GABA acts as a modulator, rather than as a classical transmitter. ABSTRACT GABA and glycine mediate fast inhibitory neurotransmission and are coreleased at several synapse types. Here we assessed the contribution of GABA and glycine in synaptic transmission between the medial nucleus of the trapezoid body (MNTB) and the lateral superior olive (LSO), two nuclei involved in sound localization. Whole-cell patch-clamp experiments in acute mouse brainstem slices at postnatal days (P) 4 and 11 during pharmacological blockade of GABAA receptors (GABAA Rs) and/or glycine receptors demonstrated no GABAergic synaptic component on LSO principal neurons. A GABAergic component was absent in evoked inhibitory postsynaptic currents and miniature events. Coimmunofluorescence experiments revealed no codistribution of the presynaptic GABAergic marker GAD65/67 with gephyrin, a postsynaptic marker for GABAA Rs, corroborating the conclusion that GABA does not act synaptically in the mouse LSO. Imaging experiments revealed reduced Ca2+ influx into MNTB axon terminals following activation of presynaptic GABAB Rs. GABAB R activation reduced the synaptic strength at P4 and P11. GABA appears to act on extrasynaptic GABAA Rs as demonstrated by application of 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol, a δ-subunit-specific GABAA R agonist. RNA sequencing showed high mRNA levels for the δ-subunit in the LSO. Moreover, GABA transporters GAT-1 and GAT-3 appear to control extracellular GABA. Finally, we show an age-dependent effect of GABA on the excitability of LSO neurons. Whereas tonic GABA increased the excitability at P4, leading to spike facilitation, it decreased the excitability at P11 via shunting inhibition through extrasynaptic GABAA Rs. Taken together, we demonstrate a modulatory role of GABA in the murine LSO, rather than a function as a classical synaptic transmitter.
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Affiliation(s)
- Alexander U. Fischer
- Animal Physiology Group, Department of BiologyUniversity of KaiserslauternD‐67663KaiserslauternGermany
| | - Nicolas I. C. Müller
- Animal Physiology Group, Department of BiologyUniversity of KaiserslauternD‐67663KaiserslauternGermany
| | - Thomas Deller
- Institute of Clinical Neuroanatomy, Neuroscience CenterGoethe‐University Frankfurt, Theodor‐Stern‐Kai 7D‐60590Frankfurt am MainGermany
| | - Domenico Del Turco
- Institute of Clinical Neuroanatomy, Neuroscience CenterGoethe‐University Frankfurt, Theodor‐Stern‐Kai 7D‐60590Frankfurt am MainGermany
| | - Jonas O. Fisch
- Animal Physiology Group, Department of BiologyUniversity of KaiserslauternD‐67663KaiserslauternGermany
| | - Désirée Griesemer
- Animal Physiology Group, Department of BiologyUniversity of KaiserslauternD‐67663KaiserslauternGermany
| | - Kathrin Kattler
- Genetics/Epigenetic Group, Department of Biological SciencesSaarland UniversityD‐66123Saarbrücken
| | - Ayse Maraslioglu
- Animal Physiology Group, Department of BiologyUniversity of KaiserslauternD‐67663KaiserslauternGermany
| | - Vera Roemer
- Animal Physiology Group, Department of BiologyUniversity of KaiserslauternD‐67663KaiserslauternGermany
| | - Matthew A. Xu‐Friedman
- Department of Biological SciencesUniversity at BuffaloState University of New YorkBuffaloNY14260USA
| | - Jörn Walter
- Genetics/Epigenetic Group, Department of Biological SciencesSaarland UniversityD‐66123Saarbrücken
| | - Eckhard Friauf
- Animal Physiology Group, Department of BiologyUniversity of KaiserslauternD‐67663KaiserslauternGermany
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Association of mGluR-Dependent LTD of Excitatory Synapses with Endocannabinoid-Dependent LTD of Inhibitory Synapses Leads to EPSP to Spike Potentiation in CA1 Pyramidal Neurons. J Neurosci 2018; 39:224-237. [PMID: 30459224 DOI: 10.1523/jneurosci.2935-17.2018] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Revised: 10/16/2018] [Accepted: 11/08/2018] [Indexed: 01/10/2023] Open
Abstract
The input-output relationships in neural circuits are determined not only by synaptic efficacy but also by neuronal excitability. Activity-dependent alterations of synaptic efficacy have been extensively investigated, but relatively less is known about how the neuronal output is modulated when synaptic efficacy changes are associated with neuronal excitability changes. In this study, we demonstrate that paired pulses of low-frequency stimulation (PP-LFS) induced metabotropic glutamate receptor (mGluR)-dependent LTD at Schaffer collateral (SC)-CA1 synapses in Sprague Dawley rats (both sexes), and this LTD was associated with EPSP to spike (E-S) potentiation, leading to the increase in action potential (AP) outputs. Threshold voltage (Vth) for APs evoked by synaptic stimulation and that by somatic current injection were hyperpolarized significantly after PP-LFS. Blockers of GABA receptors mimicked and occluded PP-LFS effects on E-S potentiation and Vth hyperpolarization, suggesting that suppression of GABAergic mechanisms is involved in E-S potentiation after PP-LFS. Indeed, IPSCs and tonic inhibitory currents were reduced after PP-LFS. The IPSC reduction was accompanied by increased paired-pulse ratio, and abolished by AM251, a blocker for Type 1 cannabinoid receptors, suggesting that PP-LFS suppresses presynaptic GABA release by mGluR-dependent endocannabinoids signaling. By contrast, a Group 1 mGluR agonist, 3, 5-dihydroxyphenylglycine, induced LTD at SC-CA1 synapses but failed to induce significant IPSC reduction and AP output increase. We propose that mGluR signaling that induces LTD coexpression at excitatory and inhibitory synapses regulates an excitation-inhibition balance to increase neuronal output in CA1 neurons.SIGNIFICANCE STATEMENT Long-lasting forms of synaptic plasticity are usually associated with excitability changes, the ability to fire action potentials. However, excitability changes have been regarded to play subsidiary roles to synaptic plasticity in modifying neuronal output. We demonstrate that, when metabotropic glutamate receptor-dependent LTD is induced by paired pulses of low-frequency stimulation, the action potential output in response to a given input paradoxically increases, indicating that increased excitability is more powerful than synaptic depression. This increase is mediated by the suppression of a presynaptic GABA release via metabotropic glutamate receptor-dependent endocannabinoid signaling. Our study shows that neuronal output changes do not always follow the direction of synaptic plasticity at excitatory synapses, highlighting the importance of regulating inhibitory tone via endocannabinoid signaling.
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Ali Rodriguez R, Joya C, Hines RM. Common Ribs of Inhibitory Synaptic Dysfunction in the Umbrella of Neurodevelopmental Disorders. Front Mol Neurosci 2018; 11:132. [PMID: 29740280 PMCID: PMC5928253 DOI: 10.3389/fnmol.2018.00132] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 04/03/2018] [Indexed: 01/06/2023] Open
Abstract
The term neurodevelopmental disorder (NDD) is an umbrella term used to group together a heterogeneous class of disorders characterized by disruption in cognition, emotion, and behavior, early in the developmental timescale. These disorders are heterogeneous, yet they share common behavioral symptomatology as well as overlapping genetic contributors, including proteins involved in the formation, specialization, and function of synaptic connections. Advances may arise from bridging the current knowledge on synapse related factors indicated from both human studies in NDD populations, and in animal models. Mounting evidence has shown a link to inhibitory synapse formation, specialization, and function among Autism, Angelman, Rett and Dravet syndromes. Inhibitory signaling is diverse, with numerous subtypes of inhibitory interneurons, phasic and tonic modes of inhibition, and the molecular and subcellular diversity of GABAA receptors. We discuss common ribs of inhibitory synapse dysfunction in the umbrella of NDD, highlighting alterations in the developmental switch to inhibitory GABA, dysregulation of neuronal activity patterns by parvalbumin-positive interneurons, and impaired tonic inhibition. Increasing our basic understanding of inhibitory synapses, and their role in NDDs is likely to produce significant therapeutic advances in behavioral symptom alleviation for interrelated NDDs.
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Affiliation(s)
- Rachel Ali Rodriguez
- Neuroscience Emphasis, Department of Psychology, University of Nevada, Las Vegas, Las Vegas, NV, United States
| | - Christina Joya
- Neuroscience Emphasis, Department of Psychology, University of Nevada, Las Vegas, Las Vegas, NV, United States
| | - Rochelle M Hines
- Neuroscience Emphasis, Department of Psychology, University of Nevada, Las Vegas, Las Vegas, NV, United States
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Pandit S, Lee GS, Park JB. Developmental changes in GABA A tonic inhibition are compromised by multiple mechanisms in preadolescent dentate gyrus granule cells. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2017; 21:695-702. [PMID: 29200913 PMCID: PMC5709487 DOI: 10.4196/kjpp.2017.21.6.695] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Revised: 09/20/2017] [Accepted: 09/21/2017] [Indexed: 01/28/2023]
Abstract
The sustained tonic currents (Itonic) generated by γ-aminobutyric acid A receptors (GABAARs) are implicated in diverse age-dependent brain functions. While various mechanisms regulating Itonic in the hippocampus are known, their combined role in Itonic regulation is not well understood in different age groups. In this study, we demonstrated that a developmental increase in GABA transporter (GAT) expression, combined with gradual decrease in GABAAR α5 subunit, resulted in various Itonic in the dentate gyrus granule cells (DGGCs) of preadolescent rats. Both GAT-1 and GAT-3 expression gradually increased at infantile (P6-8 and P13-15) and juvenile (P20-22 and P27-29) stages, with stabilization observed thereafter in adolescents (P34-36) and young adults (P41-43). Itonic facilitation of a selective GAT-1 blocker (NO-711) was significantly less at P6-8 than after P13-15. The facilitation of Itonic by SNAP-5114, a GAT-3 inhibitor, was negligible in the absence of exogenous GABA at all tested ages. In contrast, Itonic in the presence of a nonselective GAT blocker (nipecotic acid, NPA) gradually decreased with age during the preadolescent period, which was mimicked by Itonic changes in the presence of exogenous GABA. Itonic sensitivity to L-655,708, a GABAAR α5 subunit inverse agonist, gradually decreased during the preadolescent period in the presence of NPA or exogenous GABA. Finally, Western blot analysis showed that the expression of the GABAAR α5 subunit in the dentate gyrus gradually decreased with age. Collectively, our results suggested that the Itonic regulation of altered GATs is under the final tune of GABAAR α5 subunit activation in DGGCs at different ages.
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Affiliation(s)
- Sudip Pandit
- Department of Physiology, School of Medicine and Brain Research Institute, Chungnam National University, Daejeon 35015, Korea
| | - Gyu Seung Lee
- Department of Physiology, School of Medicine and Brain Research Institute, Chungnam National University, Daejeon 35015, Korea
| | - Jin Bong Park
- Department of Physiology, School of Medicine and Brain Research Institute, Chungnam National University, Daejeon 35015, Korea
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Hoshino O, Zheng M, Watanabe K. Improved Perceptual Learning by Control of Extracellular GABA Concentration by Astrocytic Gap Junctions. Neural Comput 2017; 30:184-215. [PMID: 29064786 DOI: 10.1162/neco_a_01027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Learning of sensory cues is believed to rely on synchronous pre- and postsynaptic neuronal firing. Evidence is mounting that such synchronicity is not merely caused by properties of the underlying neuronal network but could also depend on the integrity of gap junctions that connect neurons and astrocytes in networks too. In this perspective, we set out to investigate the effect of astrocytic gap junctions on perceptual learning, introducing a model for coupled neuron-astrocyte networks. In particular, we focus on the fact that astrocytes are rich of GABA transporters (GATs) which can either uptake or release GABA depending on the astrocyte membrane potential, which is a function of local neural activity. We show that GABAergic signaling is a crucial component of intracolumnar neuronal synchronization, thereby promoting learning by neurons in the same cell assembly that are activated by a shared sensory cue. At the same time, we show that this effect can critically depend on astrocytic gap junctions insofar as these latter could synchronize extracellular GABA levels around many neurons and throughout entire cell assemblies. These results are supported by extensive computational arguments and predict that astrocytic gap junctions could improve perceptual learning by controlling extracellular GABA.
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Affiliation(s)
- Osamu Hoshino
- Department of Intelligent Systems Engineering, Ibaraki University, Hitachi, Ibaraki, 316-8511, Japan, and Southern Tohoku Research Institute for Neuroscience, Southern Tohoku General Hospital, Koriyama, Fukushima, 963-8563, Japan
| | - Meihong Zheng
- Department of Psychology, Tsinghua University, Haidian District, Beijing, 100084, China
| | - Kazuo Watanabe
- Southern Tohoku Research Institute for Neuroscience, Southern Tohoku General Hospital, Koriyama, Fukushima, 963-8563, Japan
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Developmental Disruption of GABA AR-Meditated Inhibition in Cntnap2 KO Mice. eNeuro 2017; 4:eN-NWR-0162-17. [PMID: 28966979 PMCID: PMC5617210 DOI: 10.1523/eneuro.0162-17.2017] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 09/06/2017] [Accepted: 09/07/2017] [Indexed: 12/24/2022] Open
Abstract
GABA released from presynaptic sites induces short-lived phasic inhibition mediated by synaptic GABAA receptors (GABAARs) and longer-duration tonic inhibition mediated by extrasynaptic GABAA or GABAB receptors (GABABRs). A number of studies have found that contactin-associated protein 2 (Cntnap2) knockout (KO) mice, a well-established mouse model of autism, exhibit reduced interneuron numbers and aberrant phasic inhibition. However, little is known about whether tonic inhibition is disrupted in Cntnap2 KO mice and when the disruption of inhibition begins to occur during postnatal development. We examined tonic and phasic inhibition in layer 2/3 pyramidal cells of primary visual cortex of Cntnap2 KO at two different developmental stages, three to four and six to eight weeks of age. We found that both phasic inhibition and GABAAR but not GABABR-mediated tonic inhibition was reduced in pyramidal cells from six- to eight-week-old Cntnap2 KO mice, while in three- to four-week-old mice, no significant effects of genotype on tonic or phasic inhibition was observed. We further found that activation of tonic currents mediated by δ-subunit-containing GABAARs reduced neural excitability, an effect that was attenuated by loss of Cntnap2. While the relative contribution of tonic versus phasic inhibition to autism-related symptoms remains unclear, our data suggest that reduced tonic inhibition may play an important role, and δ-subunit-containing GABAARs may be a useful target for therapeutic intervention in autism.
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Decreased surface expression of the δ subunit of the GABA A receptor contributes to reduced tonic inhibition in dentate granule cells in a mouse model of fragile X syndrome. Exp Neurol 2017; 297:168-178. [PMID: 28822839 DOI: 10.1016/j.expneurol.2017.08.008] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 07/21/2017] [Accepted: 08/15/2017] [Indexed: 11/22/2022]
Abstract
While numerous changes in the GABA system have been identified in models of Fragile X Syndrome (FXS), alterations in subunits of the GABAA receptors (GABAARs) that mediate tonic inhibition are particularly intriguing. Considering the key role of tonic inhibition in controlling neuronal excitability, reduced tonic inhibition could contribute to FXS-associated disorders such as hyperactivity, hypersensitivity, and increased seizure susceptibility. The current study has focused on the expression and function of the δ subunit of the GABAAR, a major subunit involved in tonic inhibition, in granule cells of the dentate gyrus in the Fmr1 knockout (KO) mouse model of FXS. Electrophysiological studies of dentate granule cells revealed a marked, nearly four-fold, decrease in tonic inhibition in the Fmr1 KO mice, as well as reduced effects of two δ subunit-preferring pharmacological agents, THIP and DS2, supporting the suggestion that δ subunit-containing GABAARs are compromised in the Fmr1 KO mice. Immunohistochemistry demonstrated a small but statistically significant decrease in δ subunit labeling in the molecular layer of the dentate gyrus in Fmr1 KO mice compared to wildtype (WT) littermates. The discrepancy between the large deficits in GABA-mediated tonic inhibition in granule cells in the Fmr1 KO mice and only modest reductions in immunolabeling of the δ subunit led to studies of surface expression of the δ subunit. Cross-linking experiments followed by Western blot analysis demonstrated a small, non-significant decrease in total δ subunit protein in the hippocampus of Fmr1 KO mice, but a four-fold decrease in surface expression of the δ subunit in these mice. No significant changes were observed in total or surface expression of the α4 subunit protein, a major partner of the δ subunit in the forebrain. Postembedding immunogold labeling for the δ subunit demonstrated a large, three-fold, decrease in the number of symmetric synapses with immunolabeling at perisynaptic locations in Fmr1 KO mice. While α4 immunogold particles were also reduced at perisynaptic locations in the Fmr1 KO mice, the labeling was increased at synaptic sites. Together these findings suggest that, in the dentate gyrus, altered surface expression of the δ subunit, rather than a decrease in δ subunit expression alone, could be limiting δ subunit-mediated tonic inhibition in this model of FXS. Finding ways to increase surface expression of the δ subunit of the GABAAR could be a novel approach to treatment of hyperexcitability-related alterations in FXS.
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Lemos JC, Friend DM, Kaplan AR, Shin JH, Rubinstein M, Kravitz AV, Alvarez VA. Enhanced GABA Transmission Drives Bradykinesia Following Loss of Dopamine D2 Receptor Signaling. Neuron 2017; 90:824-38. [PMID: 27196975 DOI: 10.1016/j.neuron.2016.04.040] [Citation(s) in RCA: 92] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Revised: 03/22/2016] [Accepted: 04/21/2016] [Indexed: 11/26/2022]
Abstract
Bradykinesia is a prominent phenotype of Parkinson's disease, depression, and other neurological conditions. Disruption of dopamine (DA) transmission plays an important role, but progress in understanding the exact mechanisms driving slowness of movement has been impeded due to the heterogeneity of DA receptor distribution on multiple cell types within the striatum. Here we show that selective deletion of DA D2 receptors (D2Rs) from indirect-pathway medium spiny neurons (iMSNs) is sufficient to impair locomotor activity, phenocopying DA depletion models of Parkinson's disease, despite this mouse model having intact DA transmission. There was a robust enhancement of GABAergic transmission and a reduction of in vivo firing in striatal and pallidal neurons. Mimicking D2R signaling in iMSNs with Gi-DREADDs restored the level of tonic GABAergic transmission and rescued the motor deficit. These findings indicate that DA, through D2R activation in iMSNs, regulates motor output by constraining the strength of GABAergic transmission.
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Affiliation(s)
- Julia C Lemos
- National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD 20892, USA
| | - Danielle M Friend
- National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892, USA
| | - Alanna R Kaplan
- National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD 20892, USA
| | - Jung Hoon Shin
- National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD 20892, USA
| | - Marcelo Rubinstein
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, CONICET, C1428ADN Buenos Aires, Argentina; FCEN, Universidad de Buenos Aires, C1428EGA Buenos Aires, Argentina; Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Alexxai V Kravitz
- National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892, USA; National Institute on Drug Abuse, NIH, Bethesda, MD 20892, USA
| | - Veronica A Alvarez
- National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD 20892, USA.
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Joshi S, Rajasekaran K, Williamson J, Kapur J. Neurosteroid-sensitive δ-GABA A receptors: A role in epileptogenesis? Epilepsia 2017; 58:494-504. [PMID: 28452419 DOI: 10.1111/epi.13660] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/08/2016] [Indexed: 12/25/2022]
Abstract
OBJECTIVE We determined the role of the neurosteroid-sensitive δ subunit-containing γ-aminobutyric acid A receptors (δ-GABARs) in epileptogenesis. METHODS Status epilepticus (SE) was induced via lithium pilocarpine in adult rats, and seizures were assessed by continuous video-electroencephalography (EEG) monitoring. Finasteride was administered to inhibit neurosteroid synthesis. The total and surface protein expression of hippocampal δ, α4, and γ2 GABAR subunits was studied using biotinylation assays and Western blotting. Neurosteroid potentiation of the tonic currents of dentate granule cells (DGCs) was measured by whole-cell patch-clamp technique. Finally, the effects of inhibiting N-methyl-d-aspartate receptors (NMDARs) during SE on the long-term plasticity of δ-GABARs, neurosteroid-induced modulation of tonic current, and epileptogenesis were studied. RESULTS The inhibition of neurosteroid synthesis 4 days after SE triggered acute seizures and accelerated the onset of chronic recurrent spontaneous seizures (epilepsy). The down-regulation of neurosteroid-sensitive δ-GABARs occurred prior to the onset of epilepsy, whereas an increased expression of the γ2-GABAR subunits occurred after seizure onset. MK801 blockade of NMDARs during SE preserved the expression of neurosteroid-sensitive δ-GABARs. NMDAR blockade during SE also prevented the onset of spontaneous seizures. SIGNIFICANCE Changes in neurosteroid-sensitive δ-GABAR expression correlated temporally with epileptogenesis. These findings raise the possibility that δ-GABAR plasticity may play a role in epileptogenesis.
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Affiliation(s)
- Suchitra Joshi
- Department of Neurology, University of Virginia, Charlottesville, Virginia, U.S.A
| | - Karthik Rajasekaran
- Department of Neurology, University of Virginia, Charlottesville, Virginia, U.S.A
| | - John Williamson
- Department of Neurology, University of Virginia, Charlottesville, Virginia, U.S.A
| | - Jaideep Kapur
- Department of Neurology, University of Virginia, Charlottesville, Virginia, U.S.A.,Department of Neuroscience, University of Virginia, Charlottesville, Virginia, U.S.A
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Sabanov V, Braat S, D'Andrea L, Willemsen R, Zeidler S, Rooms L, Bagni C, Kooy RF, Balschun D. Impaired GABAergic inhibition in the hippocampus of Fmr1 knockout mice. Neuropharmacology 2016; 116:71-81. [PMID: 28012946 DOI: 10.1016/j.neuropharm.2016.12.010] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 11/30/2016] [Accepted: 12/12/2016] [Indexed: 01/24/2023]
Abstract
Many clinical and molecular features of the fragile X syndrome, a common form of intellectual disability and autism, can be modeled by deletion of the Fmr1 protein (Fmrp) in mice. Previous studies showed a decreased expression of several components of the GABAergic system in Fmr1 knockout mice. Here, we used this mouse model to investigate the functional consequences of Fmrp deletion on hippocampal GABAergic inhibition in the CA1-region of the hippocampus. Whole-cell patch-clamp recordings demonstrated a significantly reduced amplitude of evoked inhibitory postsynaptic currents (eIPSCs) and a decrease in the amplitude and frequency of spontaneous IPSCs. In addition, miniature IPSCs were reduced in amplitude and frequency and decayed significantly slower than mIPSCs in controls. Quantitative real-time PCR revealed a significantly lower expression of α2, β1 and δ GABAA receptor subunits in the hippocampus of the juvenile mice (P22) compared to wild-type littermates. Correspondingly, we found also at the protein level reduced amounts of α2, β1 and δ subunits in Fmr1 knockout mice. Overall, these results demonstrate that the reduction in several components of the GABAergic system is already present at young age and that this reduction results in measurable abnormalities on GABAA receptor-mediated phasic inhibition. These abnormalities might contribute to the behavioral and cognitive deficits of this fragile X mouse model.
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Affiliation(s)
- Victor Sabanov
- Laboratory of Biological Psychology, KU Leuven, Leuven, Belgium.
| | - Sien Braat
- Department of Medical Genetics, University of Antwerp, Antwerp, Belgium.
| | - Laura D'Andrea
- Center for Human Genetics-VIB Center for the Biology of Disease, KULeuven, Leuven, Belgium; Department of Biomedicine and Prevention, University of Rome Tor Vergata, Italy.
| | - Rob Willemsen
- Department of Clinical Genetics, Erasmus MC, Rotterdam, The Netherlands.
| | - Shimriet Zeidler
- Department of Clinical Genetics, Erasmus MC, Rotterdam, The Netherlands.
| | - Liesbeth Rooms
- Laboratory of Biological Psychology, KU Leuven, Leuven, Belgium.
| | - Claudia Bagni
- Center for Human Genetics-VIB Center for the Biology of Disease, KULeuven, Leuven, Belgium; Department of Biomedicine and Prevention, University of Rome Tor Vergata, Italy; Department of Fundamental Neuroscience, University of Lausanne, Switzerland.
| | - R Frank Kooy
- Department of Medical Genetics, University of Antwerp, Antwerp, Belgium.
| | - Detlef Balschun
- Laboratory of Biological Psychology, KU Leuven, Leuven, Belgium.
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van Brederode J, Atak S, Kessler A, Pischetsrieder M, Villmann C, Alzheimer C. The terpenoids Myrtenol and Verbenol act on δ subunit-containing GABAA receptors and enhance tonic inhibition in dentate gyrus granule cells. Neurosci Lett 2016; 628:91-7. [DOI: 10.1016/j.neulet.2016.06.027] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2016] [Revised: 06/09/2016] [Accepted: 06/12/2016] [Indexed: 10/21/2022]
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Hoyt LR, Ather JL, Randall MJ, DePuccio DP, Landry CC, Wewers MD, Gavrilin MA, Poynter ME. Ethanol and Other Short-Chain Alcohols Inhibit NLRP3 Inflammasome Activation through Protein Tyrosine Phosphatase Stimulation. THE JOURNAL OF IMMUNOLOGY 2016; 197:1322-34. [PMID: 27421477 DOI: 10.4049/jimmunol.1600406] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 06/12/2016] [Indexed: 11/19/2022]
Abstract
Immunosuppression is a major complication of alcoholism that contributes to increased rates of opportunistic infections and sepsis in alcoholics. The NLRP3 inflammasome, a multiprotein intracellular pattern recognition receptor complex that facilitates the cleavage and secretion of the proinflammatory cytokines IL-1β and IL-18, can be inhibited by ethanol, and we sought to better understand the mechanism through which this occurs and whether chemically similar molecules exert comparable effects. We show that ethanol can specifically inhibit activation of the NLRP3 inflammasome, resulting in attenuated IL-1β and caspase-1 cleavage and secretion, as well as diminished apoptosis-associated speck-like protein containing a CARD (ASC) speck formation, without affecting potassium efflux, in a mouse macrophage cell line (J774), mouse bone marrow-derived dendritic cells, mouse neutrophils, and human PBMCs. The inhibitory effects on the Nlrp3 inflammasome were independent of γ-aminobutyric acid A receptor activation or N-methyl-d-asparate receptor inhibition but were associated with decreased oxidant production. Ethanol treatment markedly decreased cellular tyrosine phosphorylation, whereas administration of the tyrosine phosphatase inhibitor sodium orthovanadate prior to ethanol restored tyrosine phosphorylation and IL-1β secretion subsequent to ATP stimulation. Furthermore, sodium orthovanadate-induced phosphorylation of ASC Y144, necessary and sufficient for Nlrp3 inflammasome activation, and secretion of phosphorylated ASC were inhibited by ethanol. Finally, multiple alcohol-containing organic compounds exerted inhibitory effects on the Nlrp3 inflammasome, whereas 2-methylbutane (isopentane), the analogous alkane of the potent inhibitor isoamyl alcohol (isopentanol), did not. Our results demonstrate that ethanol antagonizes the NLRP3 inflammasome at an apical event in its activation through the stimulation of protein tyrosine phosphatases, an effect shared by other short-chain alcohols.
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Affiliation(s)
- Laura R Hoyt
- Vermont Lung Center, Division of Pulmonary Disease and Critical Care, Department of Medicine, University of Vermont, Burlington, VT 05405
| | - Jennifer L Ather
- Vermont Lung Center, Division of Pulmonary Disease and Critical Care, Department of Medicine, University of Vermont, Burlington, VT 05405
| | - Matthew J Randall
- Vermont Lung Center, Division of Pulmonary Disease and Critical Care, Department of Medicine, University of Vermont, Burlington, VT 05405
| | - Daniel P DePuccio
- Department of Chemistry, University of Vermont, Burlington, VT 05405
| | - Christopher C Landry
- Department of Chemistry, University of Vermont, Burlington, VT 05405; Cellular, Molecular, and Biomedical Sciences Graduate Program, University of Vermont, Burlington, VT 05405; and
| | - Mark D Wewers
- Pulmonary, Allergy, Critical Care and Sleep Medicine, The Dorothy M. Davis Heart & Lung Research Institute, The Ohio State University, Columbus, OH 43210
| | - Mikhail A Gavrilin
- Pulmonary, Allergy, Critical Care and Sleep Medicine, The Dorothy M. Davis Heart & Lung Research Institute, The Ohio State University, Columbus, OH 43210
| | - Matthew E Poynter
- Vermont Lung Center, Division of Pulmonary Disease and Critical Care, Department of Medicine, University of Vermont, Burlington, VT 05405; Cellular, Molecular, and Biomedical Sciences Graduate Program, University of Vermont, Burlington, VT 05405; and
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40
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Shen ML, Wang CH, Chen RYT, Zhou N, Kao ST, Wu DC. Luteolin inhibits GABAA receptors in HEK cells and brain slices. Sci Rep 2016; 6:27695. [PMID: 27292079 PMCID: PMC4904371 DOI: 10.1038/srep27695] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Accepted: 05/24/2016] [Indexed: 11/23/2022] Open
Abstract
Modulation of the A type γ-aminobutyric acid receptors (GABAAR) is one of the major drug targets for neurological and psychological diseases. The natural flavonoid compound luteolin (2-(3,4-Dihydroxyphenyl)- 5,7-dihydroxy-4-chromenone) has been reported to have antidepressant, antinociceptive, and anxiolytic-like effects, which possibly involve the mechanisms of modulating GABA signaling. However, as yet detailed studies of the pharmacological effects of luteolin are still lacking, we investigated the effects of luteolin on recombinant and endogenous GABAAR-mediated current responses by electrophysiological approaches. Our results showed that luteolin inhibited GABA-mediated currents and slowed the activation kinetics of recombinant α1β2, α1β2γ2, α5β2, and α5β2γ2 receptors with different degrees of potency and efficacy. The modulatory effect of luteolin was likely dependent on the subunit composition of the receptor complex: the αβ receptors were more sensitive than the αβγ receptors. In hippocampal pyramidal neurons, luteolin significantly reduced the amplitude and slowed the rise time of miniature inhibitory postsynaptic currents (mIPSCs). However, GABAAR-mediated tonic currents were not significantly influenced by luteolin. These data suggested that luteolin has negative modulatory effects on both recombinant and endogenous GABAARs and inhibits phasic rather than tonic inhibition in hippocampus.
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Affiliation(s)
- Mei-Lin Shen
- Graduate Institute of Chinese Medicine, China Medical University, Taichung, Taiwan
| | - Chen-Hung Wang
- Graduate Institute of Clinical Medical Science, China Medical University, Taichung, Taiwan
| | - Rita Yu-Tzu Chen
- Translational Medicine Research Center, China Medical University Hospital, Taichung, Taiwan
| | - Ning Zhou
- Graduate Institute of Clinical Medical Science, China Medical University, Taichung, Taiwan.,Translational Medicine Research Center, China Medical University Hospital, Taichung, Taiwan
| | - Shung-Te Kao
- Graduate Institute of Chinese Medicine, China Medical University, Taichung, Taiwan
| | - Dong Chuan Wu
- Graduate Institute of Clinical Medical Science, China Medical University, Taichung, Taiwan.,Translational Medicine Research Center, China Medical University Hospital, Taichung, Taiwan
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41
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Abstract
Tonic inhibition mediated by extrasynaptic GABA(A) receptors (GABARs) sensing ambient levels of GABA can profoundly alter the membrane input resistance to affect cellular excitability. Therefore, regulation of tonic inhibition is an attractive mechanism to control the levels of cortical firing. In cortical pyramidal cells, tonic inhibition is regulated by age and several neurotransmitters and is affected by stroke and epilepsy. However, the possible role of sensory experience has not been examined. Here, we report that a brief 2-day exposure to dark reduces by 1/3 the inhibitory tonic conductance recorded in layer II/III pyramidal cells of the mouse juvenile (postnatal day 12-27) visual cortex. In these cells, tonic inhibition is carried primarily by GABARs containing the δ subunit. Consistently, the dark exposure reduction in conductance was associated with a reduction in δ subunit levels, which were not affected in control frontal cortex. We propose that a deprivation-induced reduction in tonic inhibition might serve a homeostatic function by increasing the firing levels of cells in deprived cortical circuits.
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42
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Tong X, Peng Z, Zhang N, Cetina Y, Huang CS, Wallner M, Otis TS, Houser CR. Ectopic Expression of α6 and δ GABAA Receptor Subunits in Hilar Somatostatin Neurons Increases Tonic Inhibition and Alters Network Activity in the Dentate Gyrus. J Neurosci 2015; 35:16142-58. [PMID: 26658866 PMCID: PMC4682781 DOI: 10.1523/jneurosci.2853-15.2015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Revised: 10/23/2015] [Accepted: 11/01/2015] [Indexed: 11/21/2022] Open
Abstract
The role of GABAA receptor (GABAAR)-mediated tonic inhibition in interneurons remains unclear and may vary among subgroups. Somatostatin (SOM) interneurons in the hilus of the dentate gyrus show negligible expression of nonsynaptic GABAAR subunits and very low tonic inhibition. To determine the effects of ectopic expression of tonic GABAAR subtypes in these neurons, Cre-dependent viral vectors were used to express GFP-tagged GABAAR subunits (α6 and δ) selectively in hilar SOM neurons in SOM-Cre mice. In single-transfected animals, immunohistochemistry demonstrated strong expression of either the α6 or δ subunit; in cotransfected animals, both subunits were consistently expressed in the same neurons. Electrophysiology revealed a robust increase of tonic current, with progressively larger increases following transfection of δ, α6, and α6/δ subunits, respectively, indicating formation of functional receptors in all conditions and likely coassembly of the subunits in the same receptor following cotransfection. An in vitro model of repetitive bursting was used to determine the effects of increased tonic inhibition in hilar SOM interneurons on circuit activity in the dentate gyrus. Upon cotransfection, the frequency of GABAAR-mediated bursting in granule cells was reduced, consistent with a reduction in synchronous firing among hilar SOM interneurons. Moreover, in vivo studies of Fos expression demonstrated reduced activation of α6/δ-cotransfected neurons following acute seizure induction by pentylenetetrazole. The findings demonstrate that increasing tonic inhibition in hilar SOM interneurons can alter dentate gyrus circuit activity during strong stimulation and suggest that tonic inhibition of interneurons could play a role in regulating excessive synchrony within the network. SIGNIFICANCE STATEMENT In contrast to many hippocampal interneurons, somatostatin (SOM) neurons in the hilus of the dentate gyrus have very low levels of nonsynaptic GABAARs and exhibit very little tonic inhibition. In an effort to increase tonic inhibition selectively in these interneurons, we used Cre-dependent viral vectors in SOM-Cre mice to achieve interneuron-specific expression of the nonsynaptic GABAAR subunits (α6 and δ) in vivo. We show, for the first time, that such recombinant GFP-tagged GABAAR subunits are expressed robustly, assemble to form functional receptors, substantially increase tonic inhibition in SOM interneurons, and alter circuit activity within the dentate gyrus.
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Affiliation(s)
- Xiaoping Tong
- Departments of Neurobiology and Department of Anatomy, Histology and Embryology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China, and
| | | | | | | | | | - Martin Wallner
- Molecular and Medical Pharmacology and Brain Research Institute, David Geffen School of Medicine at the University of California, Los Angeles, Los Angeles, California 90095
| | - Thomas S Otis
- Departments of Neurobiology and Brain Research Institute, David Geffen School of Medicine at the University of California, Los Angeles, Los Angeles, California 90095, Roche Pharmaceutical Research and Early Development, Neuroscience, Ophthalmology, and Rare Diseases Translational Area, Roche Innovation Center Basel, CH-4070, Basel, Switzerland
| | - Carolyn R Houser
- Departments of Neurobiology and Brain Research Institute, David Geffen School of Medicine at the University of California, Los Angeles, Los Angeles, California 90095,
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Rodgers FC, Zarnowska ED, Laha KT, Engin E, Zeller A, Keist R, Rudolph U, Pearce RA. Etomidate Impairs Long-Term Potentiation In Vitro by Targeting α5-Subunit Containing GABAA Receptors on Nonpyramidal Cells. J Neurosci 2015; 35:9707-16. [PMID: 26134653 PMCID: PMC4571505 DOI: 10.1523/jneurosci.0315-15.2015] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2015] [Revised: 05/07/2015] [Accepted: 05/28/2015] [Indexed: 02/07/2023] Open
Abstract
Previous experiments using genetic and pharmacological manipulations have provided strong evidence that etomidate impairs synaptic plasticity and memory by modulating α5-subunit containing GABAA receptors (α5-GABAARs). Because α5-GABAARs mediate tonic inhibition (TI) in hippocampal CA1 pyramidal cells and etomidate enhances TI, etomidate enhancement of TI in pyramidal cells has been proposed as the underlying mechanism (Martin et al., 2009). Here we tested this hypothesis by selectively removing α5-GABAARs from pyramidal neurons (CA1-pyr-α5-KO) and comparing the ability of etomidate to enhance TI and block LTP in fl-α5 (WT), global-α5-KO (gl-α5-KO), and CA1-pyr-α5-KO mice. Etomidate suppressed LTP in slices from WT and CA1-pyr-α5-KO but not gl-α5-KO mice. There was a trend toward reduced TI in both gl-α5-KO and CA1-pyr-α5-KO mice, but etomidate enhanced TI to similar levels in all genotypes. The dissociation between effects of etomidate on TI and LTP in gl-α5-KO mice indicates that increased TI in pyramidal neurons is not the mechanism by which etomidate impairs LTP and memory. Rather, the ability of etomidate to block LTP in WT and CA1-pyr-α5-KO mice, but not in gl-α5-KO mice, points toward α5-GABAARs on nonpyramidal cells as the essential effectors controlling plasticity in this in vitro model of learning and memory.
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Affiliation(s)
- F Clifford Rodgers
- Neuroscience Training Program and Department of Anesthesiology, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - Ewa D Zarnowska
- Department of Anesthesiology, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - Kurt T Laha
- Department of Anesthesiology, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - Elif Engin
- Laboratory of Genetic Neuropharmacology, McLean Hospital, Belmont, Massachusetts 02478, Department of Psychiatry, Harvard Medical School, Boston, Massachusetts 02215, and
| | - Anja Zeller
- Institute of Pharmacology and Toxicology, University of Zurich, CH-8057 Zurich, Switzerland
| | - Ruth Keist
- Institute of Pharmacology and Toxicology, University of Zurich, CH-8057 Zurich, Switzerland
| | - Uwe Rudolph
- Laboratory of Genetic Neuropharmacology, McLean Hospital, Belmont, Massachusetts 02478, Department of Psychiatry, Harvard Medical School, Boston, Massachusetts 02215, and
| | - Robert A Pearce
- Department of Anesthesiology, University of Wisconsin-Madison, Madison, Wisconsin 53706,
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44
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Martín V, Vale C, Hirama M, Yamashita S, Rubiolo JA, Vieytes MR, Botana LM. Synthetic ciguatoxin CTX 3C induces a rapid imbalance in neuronal excitability. Chem Res Toxicol 2015; 28:1095-108. [PMID: 25945403 DOI: 10.1021/tx500503d] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Ciguatera is a human global disease caused by the consumption of contaminated fish that have accumulated ciguatoxins (CTXs), sodium channel activator toxins. Symptoms of ciguatera include neurological alterations such as paraesthesiae, dysaesthesiae, depression, and heightened nociperception, among others. An important issue to understand these long-term neurological alterations is to establish the role that changes in activity produced by CTX 3C represent to neurons. Here, the effects of synthetic ciguatoxin CTX 3C on membrane potential, spontaneous spiking, and properties of synaptic transmission in cultured cortical neurons of 11-18 days in vitro (DIV) were evaluated using electrophysiological approaches. CTX 3C induced a large depolarization that decreased neuronal firing and caused a rapid inward tonic current that was primarily GABAergic. Moreover, the toxin enhanced the amplitude of miniature postsynaptic inhibitory currents (mIPSCs), whereas it decreased the amplitude of miniature postsynaptic excitatory currents (mEPSCs). The frequency of mIPSCs increased, whereas the frequency of mEPSCs remained unaltered. We describe, for the first time, that a rapid membrane depolarization caused by CTX 3C in cortical neurons activates mechanisms that tend to suppress electrical activity by shifting the balance between excitatory and inhibitory synaptic transmission toward inhibition. Indeed, these results suggest that the acute effects of CTX on synaptic transmission could underlie some of the neurological symptoms caused by ciguatera in humans.
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Affiliation(s)
- Victor Martín
- †Departamento de Farmacología, Facultad de Veterinaria, Universidad de Santiago de Compostela, 27002 Lugo, Spain
| | - Carmen Vale
- †Departamento de Farmacología, Facultad de Veterinaria, Universidad de Santiago de Compostela, 27002 Lugo, Spain
| | - Masahiro Hirama
- ‡Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan
| | - Shuji Yamashita
- ‡Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan
| | - Juan Andrés Rubiolo
- †Departamento de Farmacología, Facultad de Veterinaria, Universidad de Santiago de Compostela, 27002 Lugo, Spain
| | - Mercedes R Vieytes
- §Departamento de Fisiología, Facultad de Veterinaria, Universidad de Santiago de Compostela, 27002 Lugo, Spain
| | - Luis M Botana
- †Departamento de Farmacología, Facultad de Veterinaria, Universidad de Santiago de Compostela, 27002 Lugo, Spain
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45
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Hogg DW, Pamenter ME, Dukoff DJ, Buck LT. Decreases in mitochondrial reactive oxygen species initiate GABA(A) receptor-mediated electrical suppression in anoxia-tolerant turtle neurons. J Physiol 2015; 593:2311-26. [PMID: 25781154 DOI: 10.1113/jp270474] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 03/12/2015] [Indexed: 12/16/2022] Open
Abstract
Anoxia induces hyper-excitability and cell death in mammalian brain but in the anoxia-tolerant western painted turtle (Chrysemys picta bellii) neuronal electrical activity is suppressed (i.e. spike arrest), adenosine triphosphate (ATP) consumption is reduced, and cell death does not occur. Electrical suppression is primarily the result of enhanced γ-aminobutyric acid (GABA) transmission; however, the underlying mechanism responsible for initiating oxygen-sensitive GABAergic spike arrest is unknown. In turtle cortical pyramidal neurons there are three types of GABA(A) receptor-mediated currents: spontaneous inhibitory postsynaptic currents (IPSCs), giant IPSCs and tonic currents. The aim of this study was to assess the effects of reactive oxygen species (ROS) scavenging on these three currents since ROS levels naturally decrease with anoxia and may serve as a redox signal to initiate spike arrest. We found that anoxia, pharmacological ROS scavenging, or inhibition of mitochondrial ROS generation enhanced all three types of GABA currents, with tonic currents comprising ∼50% of the total current. Application of hydrogen peroxide inhibited all three GABA currents, demonstrating a reversible redox-sensitive signalling mechanism. We conclude that anoxia-mediated decreases in mitochondrial ROS production are sufficient to initiate a redox-sensitive inhibitory GABA signalling cascade that suppresses electrical activity when oxygen is limited. This unique strategy for reducing neuronal ATP consumption during anoxia represents a natural mechanism in which to explore therapies to protect mammalian brain from low-oxygen insults.
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Affiliation(s)
- David W Hogg
- Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada, M5S 3G5
| | - Matthew E Pamenter
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4
| | - David J Dukoff
- Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada, M5S 3G5
| | - Leslie T Buck
- Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada, M5S 3G5.,Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada, M5S 3G5
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46
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Sebe JY, Looke-Stewart E, Baraban SC. GABAB receptors in maintenance of neocortical circuit function. Exp Neurol 2014; 261:163-70. [PMID: 24873729 PMCID: PMC4324605 DOI: 10.1016/j.expneurol.2014.05.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2014] [Revised: 05/04/2014] [Accepted: 05/19/2014] [Indexed: 10/25/2022]
Abstract
Activation of metabotropic GABAB receptors (GABABRs) enhances tonic GABA current and substantially increases the frequency of spontaneous seizures. Despite the and pro-epileptic consequences of GABABR activation, mice lacking functional GABAB receptors (GABAB1R KO mice) exhibit clonic and rare absence seizures. To examine these mutant mice further, we recorded excitatory and inhibitory synaptic inputs and tonic mutant GABA currents from Layer 2 neocortical pyramidal neurons of GABAB1R WT and KO mice (P30-40). Tonic current was increased while the frequency of synaptic inputs was unchanged in KO mice relative to WT littermates. The neocortical laminar distribution of interneuron subtypes derived from the medial ganglionic eminence (MGE) was also not statistically different in KO mice relative to WT while the number of calretinin-positive, caudal GE-derived cells in Layer 1 was reduced. Transplantation of MGE progenitors obtained from KO mice lacking functional GABAB1R did not increase tonic inhibition in the host brain above that of media-injected controls. Taken together, these results suggest a complex role for GABAB receptors in mediating neocortical circuit function.
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Affiliation(s)
- Joy Y Sebe
- Department of Neurological Surgery, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Elizabeth Looke-Stewart
- Department of Neurological Surgery, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Scott C Baraban
- Department of Neurological Surgery, University of California, San Francisco, San Francisco, CA 94143, USA; Graduate Program in Neuroscience, University of California, San Francisco, San Francisco, CA 941432, USA; The Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA 94143, USA.
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47
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Abstract
Hydrogen peroxide (H2O2), a key reactive oxygen species, is produced at low levels during normal cellular metabolism and at higher concentrations under pathological conditions such as ischemia-reperfusion injury. The mechanisms by which H2O2 contributes to physiological and pathological processes in the brain remain poorly understood. Inhibitory GABA type A (GABAA) receptors critically regulate brain function by generating tonic and synaptic currents; however, it remains unknown whether H2O2 directly modulates GABAA receptor function. Here, we performed patch-clamp recordings, together with pharmacological and genetic approaches, to investigate the effects of H2O2 on GABAA receptor-mediated tonic and synaptic currents recorded in cultured mouse hippocampal neurons and CA1 pyramidal neurons in hippocampal slices. We found that H2O2 caused a dramatic increase in tonic current, whereas synaptic currents were unaffected. This increase in tonic current resulted from an extracellular oxidative reaction, which increased the potency of GABA, but only when GABAA receptors were activated by low concentrations of GABA. Oxygen-glucose deprivation, which produces high endogenous levels of H2O2, similarly increased the tonic current. These results suggest that GABAA receptor-mediated tonic current, which is potentiated by H2O2, might contribute to H2O2-induced brain dysfunction.
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48
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Medrihan L, Ferrea E, Greco B, Baldelli P, Benfenati F. Asynchronous GABA Release Is a Key Determinant of Tonic Inhibition and Controls Neuronal Excitability: A Study in the Synapsin II-/- Mouse. Cereb Cortex 2014; 25:3356-68. [PMID: 24962993 PMCID: PMC4585492 DOI: 10.1093/cercor/bhu141] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Idiopathic epilepsies have frequently been linked to mutations in voltage-gated channels (channelopathies); recently, mutations in several genes encoding presynaptic proteins have been shown to cause epilepsy in humans and mice, indicating that epilepsy can also be considered a synaptopathy. However, the functional mechanisms by which presynaptic dysfunctions lead to hyperexcitability and seizures are not well understood. We show that deletion of synapsin II (Syn II), a presynaptic protein contributing to epilepsy predisposition in humans, leads to a loss of tonic inhibition in mouse hippocampal slices due to a dramatic decrease in presynaptic asynchronous GABA release. We also show that the asynchronous GABA release reduces postsynaptic cell firing, and the parallel impairment of asynchronous GABA release and tonic inhibition results in an increased excitability at both single-neuron and network levels. Restoring tonic inhibition with THIP (4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol; gaboxadol), a selective agonist of δ subunit-containing GABAA receptors, fully rescues the SynII−/− epileptic phenotype both ex vivo and in vivo. The results demonstrate a causal relationship between the dynamics of GABA release and the generation of tonic inhibition, and identify a novel mechanism of epileptogenesis generated by dysfunctions in the dynamics of release that can be effectively targeted by novel antiepileptic strategies.
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Affiliation(s)
- Lucian Medrihan
- Department of Neuroscience and Brain Technologies, Fondazione Istituto Italiano di Tecnologia, 16163 Genoa, Italy
| | - Enrico Ferrea
- Department of Neuroscience and Brain Technologies, Fondazione Istituto Italiano di Tecnologia, 16163 Genoa, Italy
| | - Barbara Greco
- Department of Neuroscience and Brain Technologies, Fondazione Istituto Italiano di Tecnologia, 16163 Genoa, Italy
| | - Pietro Baldelli
- Department of Neuroscience and Brain Technologies, Fondazione Istituto Italiano di Tecnologia, 16163 Genoa, Italy Department of Experimental Medicine, University of Genoa, 16132 Genoa, Italy
| | - Fabio Benfenati
- Department of Neuroscience and Brain Technologies, Fondazione Istituto Italiano di Tecnologia, 16163 Genoa, Italy Department of Experimental Medicine, University of Genoa, 16132 Genoa, Italy
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