1
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Arora I, Mal P, Arora P, Paul A, Kumar M. GABAergic implications in anxiety and related disorders. Biochem Biophys Res Commun 2024; 724:150218. [PMID: 38865810 DOI: 10.1016/j.bbrc.2024.150218] [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: 02/28/2024] [Revised: 05/05/2024] [Accepted: 06/02/2024] [Indexed: 06/14/2024]
Abstract
Evidence indicates that anxiety disorders arise from an imbalance in the functioning of brain circuits that govern the modulation of emotional responses to possibly threatening stimuli. The circuits under consideration in this context include the amygdala's bottom-up activity, which signifies the existence of stimuli that may be seen as dangerous. Moreover, these circuits encompass top-down regulatory processes that originate in the prefrontal cortex, facilitating the communication of the emotional significance associated with the inputs. Diverse databases (e.g., Pubmed, ScienceDirect, Web of Science, Google Scholar) were searched for literature using a combination of different terms e.g., "anxiety", "stress", "neuroanatomy", and "neural circuits", etc. A decrease in GABAergic activity is present in both anxiety disorders and severe depression. Research on cerebral functional imaging in depressive individuals has shown reduced levels of GABA within the cortical regions. Additionally, animal studies demonstrated that a reduction in the expression of GABAA/B receptors results in a behavioral pattern resembling anxiety. The amygdala consists of inhibitory networks composed of GABAergic interneurons, responsible for modulating anxiety responses in both normal and pathological conditions. The GABAA receptor has allosteric sites (e.g., α/γ, γ/β, and α/β) which enable regulation of neuronal inhibition in the amygdala. These sites serve as molecular targets for anxiolytic medications such as benzodiazepine and barbiturates. Alterations in the levels of naturally occurring regulators of these allosteric sites, along with alterations to the composition of the GABAA receptor subunits, could potentially act as mechanisms via which the extent of neuronal inhibition is diminished in pathological anxiety disorders.
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Affiliation(s)
- Indu Arora
- Chitkara College of Pharmacy, Chitkara University, Punjab, India
| | - Pankaj Mal
- Chitkara College of Pharmacy, Chitkara University, Punjab, India
| | - Poonam Arora
- Chitkara College of Pharmacy, Chitkara University, Punjab, India
| | - Anushka Paul
- Chitkara College of Pharmacy, Chitkara University, Punjab, India
| | - Manish Kumar
- Chitkara College of Pharmacy, Chitkara University, Punjab, India.
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2
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Proddutur A, Nguyen S, Yeh CW, Gupta A, Santhakumar V. Reclusive chandeliers: Functional isolation of dentate axo-axonic cells after experimental status epilepticus. Prog Neurobiol 2023; 231:102542. [PMID: 37898313 PMCID: PMC10842856 DOI: 10.1016/j.pneurobio.2023.102542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 10/22/2023] [Accepted: 10/24/2023] [Indexed: 10/30/2023]
Abstract
Axo-axonic cells (AACs) provide specialized inhibition to the axon initial segment (AIS) of excitatory neurons and can regulate network output and synchrony. Although hippocampal dentate AACs are structurally altered in epilepsy, physiological analyses of dentate AACs are lacking. We demonstrate that parvalbumin neurons in the dentate molecular layer express PTHLH, an AAC marker, and exhibit morphology characteristic of AACs. Dentate AACs show high-frequency, non-adapting firing but lack persistent firing in the absence of input and have higher rheobase than basket cells suggesting that AACs can respond reliably to network activity. Early after pilocarpine-induced status epilepticus (SE), dentate AACs receive fewer spontaneous excitatory and inhibitory synaptic inputs and have significantly lower maximum firing frequency. Paired recordings and spatially localized optogenetic stimulation revealed that SE reduced the amplitude of unitary synaptic inputs from AACs to granule cells without altering reliability, short-term plasticity, or AIS GABA reversal potential. These changes compromised AAC-dependent shunting of granule cell firing in a multicompartmental model. These early post-SE changes in AAC physiology would limit their ability to receive and respond to input, undermining a critical brake on the dentate throughput during epileptogenesis.
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Affiliation(s)
- Archana Proddutur
- Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, Newark, NJ 07103, USA; Department of Molecular, Cell and Systems Biology, University of California Riverside, Riverside, CA 92521, USA
| | - Susan Nguyen
- Department of Molecular, Cell and Systems Biology, University of California Riverside, Riverside, CA 92521, USA
| | - Chia-Wei Yeh
- Department of Molecular, Cell and Systems Biology, University of California Riverside, Riverside, CA 92521, USA
| | - Akshay Gupta
- Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, Newark, NJ 07103, USA; Department of Molecular, Cell and Systems Biology, University of California Riverside, Riverside, CA 92521, USA
| | - Vijayalakshmi Santhakumar
- Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, Newark, NJ 07103, USA; Department of Molecular, Cell and Systems Biology, University of California Riverside, Riverside, CA 92521, USA.
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3
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Proddutur A, Nguyen S, Yeh CW, Gupta A, Santhakumar V. RECLUSIVE CHANDELIERS: FUNCTIONAL ISOLATION OF DENTATE AXO-AXONIC CELLS AFTER EXPERIMENTAL STATUS EPILEPTICUS. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.01.560378. [PMID: 37873292 PMCID: PMC10592856 DOI: 10.1101/2023.10.01.560378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Axo-axonic cells (AACs) provide specialized inhibition to the axon initial segment (AIS) of excitatory neurons and can regulate network output and synchrony. Although hippocampal dentate AACs are structurally altered in epilepsy, physiological analyses of dentate AACs are lacking. We demonstrate that parvalbumin neurons in the dentate molecular layer express PTHLH, an AAC marker, and exhibit morphology characteristic of AACs. Dentate AACs show high-frequency, non-adapting firing but lack persistent firing in the absence of input and have higher rheobase than basket cells suggesting that AACs can respond reliably to network activity. Early after pilocarpine-induced status epilepticus (SE), dentate AACs receive fewer spontaneous excitatory and inhibitory synaptic inputs and have significantly lower maximum firing frequency. Paired recordings and spatially localized optogenetic stimulation revealed that SE reduced the amplitude of unitary synaptic inputs from AACs to granule cells without altering reliability, short-term plasticity, or AIS GABA reversal potential. These changes compromised AAC-dependent shunting of granule cell firing in a multicompartmental model. These early post-SE changes in AAC physiology would limit their ability to receive and respond to input, undermining a critical brake on the dentate throughput during epileptogenesis.
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Affiliation(s)
- Archana Proddutur
- Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, Newark, New Jersey 07103
- Department of Molecular, Cell and Systems Biology, University of California Riverside, Riverside, California 92521
| | - Susan Nguyen
- Department of Molecular, Cell and Systems Biology, University of California Riverside, Riverside, California 92521
| | - Chia-Wei Yeh
- Department of Molecular, Cell and Systems Biology, University of California Riverside, Riverside, California 92521
| | - Akshay Gupta
- Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, Newark, New Jersey 07103
- Department of Molecular, Cell and Systems Biology, University of California Riverside, Riverside, California 92521
| | - Vijayalakshmi Santhakumar
- Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, Newark, New Jersey 07103
- Department of Molecular, Cell and Systems Biology, University of California Riverside, Riverside, California 92521
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4
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Lipkin AM, Bender KJ. Axon Initial Segment GABA Inhibits Action Potential Generation throughout Periadolescent Development. J Neurosci 2023; 43:6357-6368. [PMID: 37596053 PMCID: PMC10500977 DOI: 10.1523/jneurosci.0605-23.2023] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2023] [Revised: 07/04/2023] [Accepted: 08/01/2023] [Indexed: 08/20/2023] Open
Abstract
Neurons are remarkably polarized structures: dendrites spread and branch to receive synaptic inputs while a single axon extends and transmits action potentials (APs) to downstream targets. Neuronal polarity is maintained by the axon initial segment (AIS), a region between the soma and axon proper that is also the site of action potential (AP) generation. This polarization between dendrites and axons extends to inhibitory neurotransmission. In adulthood, the neurotransmitter GABA hyperpolarizes dendrites but instead depolarizes axons. These differences in function collide at the AIS. Multiple studies have shown that GABAergic signaling in this region can share properties of either the mature axon or mature dendrite, and that these properties evolve over a protracted period encompassing periadolescent development. Here, we explored how developmental changes in GABAergic signaling affect AP initiation. We show that GABA at the axon initial segment inhibits action potential initiation in layer (L)2/3 pyramidal neurons in prefrontal cortex from mice of either sex across GABA reversal potentials observed in periadolescence. These actions occur largely through current shunts generated by GABAA receptors and changes in voltage-gated channel properties that affected the number of channels that could be recruited for AP electrogenesis. These results suggest that GABAergic neurons targeting the axon initial segment provide an inhibitory "veto" across the range of GABA polarity observed in normal adolescent development, regardless of GABAergic synapse reversal potential.Significance Statement GABA receptors are a major class of neurotransmitter receptors in the brain. Typically, GABA receptors inhibit neurons by allowing influx of negatively charged chloride ions into the cell. However, there are cases where local chloride concentrations promote chloride efflux through GABA receptors. Such conditions exist early in development in neocortical pyramidal cell axon initial segments (AISs), where action potentials (APs) initiate. Here, we examined how chloride efflux in early development interacts with mechanisms that support action potential initiation. We find that this efflux, despite moving membrane potential closer to action potential threshold, is nevertheless inhibitory. Thus, GABA at the axon initial segment is likely to be inhibitory for action potential initiation independent of whether chloride flows out or into neurons via these receptors.
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Affiliation(s)
- Anna M Lipkin
- Neuroscience Graduate Program
- Center for Integrative Neuroscience Department of Neurology, University of California, San Francisco 94158, California
| | - Kevin J Bender
- Center for Integrative Neuroscience Department of Neurology, University of California, San Francisco 94158, California
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5
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Tian D, Izumi SI. Transcranial Magnetic Stimulation and Neocortical Neurons: The Micro-Macro Connection. Front Neurosci 2022; 16:866245. [PMID: 35495053 PMCID: PMC9039343 DOI: 10.3389/fnins.2022.866245] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 02/28/2022] [Indexed: 12/20/2022] Open
Abstract
Understanding the operation of cortical circuits is an important and necessary task in both neuroscience and neurorehabilitation. The functioning of the neocortex results from integrative neuronal activity, which can be probed non-invasively by transcranial magnetic stimulation (TMS). Despite a clear indication of the direct involvement of cortical neurons in TMS, no explicit connection model has been made between the microscopic neuronal landscape and the macroscopic TMS outcome. Here we have performed an integrative review of multidisciplinary evidence regarding motor cortex neurocytology and TMS-related neurophysiology with the aim of elucidating the micro–macro connections underlying TMS. Neurocytological evidence from animal and human studies has been reviewed to describe the landscape of the cortical neurons covering the taxonomy, morphology, circuit wiring, and excitatory–inhibitory balance. Evidence from TMS studies in healthy humans is discussed, with emphasis on the TMS pulse and paradigm selectivity that reflect the underlying neural circuitry constitution. As a result, we propose a preliminary neuronal model of the human motor cortex and then link the TMS mechanisms with the neuronal model by stimulus intensity, direction of induced current, and paired-pulse timing. As TMS bears great developmental potential for both a probe and modulator of neural network activity and neurotransmission, the connection model will act as a foundation for future combined studies of neurocytology and neurophysiology, as well as the technical advances and application of TMS.
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Affiliation(s)
- Dongting Tian
- Department of Physical Medicine and Rehabilitation, Tohoku University Graduates School of Medicine, Sendai, Japan
- *Correspondence: Dongting Tian,
| | - Shin-Ichi Izumi
- Department of Physical Medicine and Rehabilitation, Tohoku University Graduates School of Medicine, Sendai, Japan
- Graduate School of Biomedical Engineering, Tohoku University, Sendai, Japan
- Shin-Ichi Izumi,
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6
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GABA A Receptor Autoantibodies Decrease GABAergic Synaptic Transmission in the Hippocampal CA3 Network. Int J Mol Sci 2022; 23:ijms23073707. [PMID: 35409067 PMCID: PMC8998798 DOI: 10.3390/ijms23073707] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Revised: 03/19/2022] [Accepted: 03/23/2022] [Indexed: 12/04/2022] Open
Abstract
Autoimmune encephalitis associated with antibodies (Abs) against α1, β3, and γ2 subunits of γ-aminobutyric acid receptor A (GABAAR) represents a severe form of encephalitis with refractory seizures and status epilepticus. Reduction in inhibitory GABAergic synaptic activity is linked to dysfunction of neuronal networks, hyperexcitability, and seizures. The aim in this study was to investigate the direct pathogenic effect of a recombinant GABAAR autoantibody (rAb-IP2), derived from the cerebrospinal fluid (CSF) of a patient with autoimmune GABAAR encephalitis, on hippocampal CA1 and CA3 networks. Acute brain slices from C57BL/6 mice were incubated with rAb-IP2. The spontaneous synaptic GABAergic transmission was measured using electrophysiological recordings in voltage-clamp mode. The GABAAR autoantibody rAb-IP2 reduced inhibitory postsynaptic signaling in the hippocampal CA1 pyramidal neurons with regard to the number of spontaneous inhibitory postsynaptic currents (sIPSCs) but did not affect their amplitude. In the hippocampal CA3 network, decreased number and amplitude of sIPSCs were detected, leading to decreased GABAergic synaptic transmission. Immunohistochemical staining confirmed the rAb-IP2 bound to hippocampal tissue. These findings suggest that GABAAR autoantibodies exert direct functional effects on both hippocampal CA1 and CA3 pyramidal neurons and play a crucial role in seizure generation in GABAAR autoimmune encephalitis.
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7
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Schulte C, Maric HM. Expanding GABA AR pharmacology via receptor-associated proteins. Curr Opin Pharmacol 2021; 57:98-106. [PMID: 33684670 DOI: 10.1016/j.coph.2021.01.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 01/18/2021] [Accepted: 01/26/2021] [Indexed: 02/06/2023]
Abstract
Drugs directly targeting γ-aminobutyric acid type A receptors (GABAARs), the major mediators of fast synaptic inhibition, contribute significantly to today's neuropharmacology. Emerging evidence establishes intracellularly GABAAR-associated proteins as the central players in determining cellular and subcellular GABAergic input sites, thereby providing pharmacological opportunities to affect distinct receptor populations and address discrete neuronal dysfunctions. Here, we report on recently studied GABAAR-associated proteins and highlight challenges and newly available methods for their functional and physical mapping. We anticipate these efforts to contribute to decipher the complexity of GABAergic signalling in the brain and eventually enable therapeutic avenues for, so far, untreatable neuronal disorders and diseases.
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Affiliation(s)
- Clemens Schulte
- Department of Biotechnology and Biophysics and Rudolf Virchow Center for Integrative and Translational Bioimaging, University of Würzburg, Josef-Schneider-Str. 2, D15, 97080, Würzburg, Germany
| | - Hans Michael Maric
- Department of Biotechnology and Biophysics and Rudolf Virchow Center for Integrative and Translational Bioimaging, University of Würzburg, Josef-Schneider-Str. 2, D15, 97080, Würzburg, Germany.
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8
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Syed P, Durisic N, Harvey RJ, Sah P, Lynch JW. Effects of GABA A Receptor α3 Subunit Epilepsy Mutations on Inhibitory Synaptic Signaling. Front Mol Neurosci 2020; 13:602559. [PMID: 33328885 PMCID: PMC7714833 DOI: 10.3389/fnmol.2020.602559] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 10/02/2020] [Indexed: 11/13/2022] Open
Abstract
Missense mutations T166M, Q242L, T336M, and Y474C in the GABAA receptor (GABAAR) α3 subunit gene are associated with epileptic seizures, dysmorphic features, intellectual disability, and developmental delay. When incorporated into GABAARs expressed in oocytes, all mutations are known to reduce GABA-evoked whole-cell currents. However, their impact on the properties of inhibitory synaptic currents (IPSCs) is unknown, largely because it is difficult to establish, much less control, the stoichiometry of GABAAR expressed in native neuronal synapses. To circumvent this problem, we employed a HEK293 cell-neuron co-culture expression system that permits the recording of IPSCs mediated by a pure population of GABAARs with a defined stoichiometry. We first demonstrated that IPSCs mediated by α3-containing GABAARs (α3β3γ2) decay significantly slower than those mediated by α1-containing isoforms (α1β2γ2 or α1β3γ2). GABAAR α3 mutations did not affect IPSC peak amplitudes or 10-90% rise times, but three of the mutations affected IPSC decay. T336M significantly accelerated the IPSC decay rate whereas T166M and Y474C had the opposite effect. The acceleration of IPSC decay kinetics caused by the T366M mutation was returned to wild-type-like values by the anti-epileptic medication, midazolam. Quantification experiments in HEK293 cells revealed a significant reduction in cell-surface expression for all mutants, in agreement with previous oocyte data. Taken together, our results show that impaired surface expression and altered IPSC decay rates could both be significant factors underlying the pathologies associated with these mutations.
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Affiliation(s)
- Parnayan Syed
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Nela Durisic
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Robert J Harvey
- School of Health and Behavioural Sciences, University of the Sunshine Coast, Maroochydore, QLD, Australia.,Sunshine Coast Health Institute, Birtinya, QLD, Australia
| | - Pankaj Sah
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia.,Department of Biology, Joint Center for Neuroscience and Neural Engineering, Southern University of Science and Technology, Shenzhen, China
| | - Joseph W Lynch
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
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9
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Gavrilovici C, Jiang Y, Kiroski I, Teskey GC, Rho JM, Nguyen MD. Postnatal Role of the Cytoskeleton in Adult Epileptogenesis. Cereb Cortex Commun 2020; 1:tgaa024. [PMID: 32864616 PMCID: PMC7446231 DOI: 10.1093/texcom/tgaa024] [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: 06/08/2020] [Revised: 06/08/2020] [Accepted: 06/11/2020] [Indexed: 02/07/2023] Open
Abstract
Mutations in cytoskeletal proteins can cause early infantile and childhood epilepsies by misplacing newly born neurons and altering neuronal connectivity. In the adult epileptic brain, cytoskeletal disruption is often viewed as being secondary to aberrant neuronal activity and/or death, and hence simply represents an epiphenomenon. Here, we review the emerging evidence collected in animal models and human studies implicating the cytoskeleton as a potential causative factor in adult epileptogenesis. Based on the emerging evidence, we propose that cytoskeletal disruption may be an important pathogenic mechanism in the mature epileptic brain.
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Affiliation(s)
- Cezar Gavrilovici
- Departments of Neurosciences & Pediatrics, University of California San Diego, Rady Children's Hospital San Diego, San Diego, CA 92123, USA
| | - Yulan Jiang
- Departments of Clinical Neurosciences, Cell Biology & Anatomy, and Biochemistry & Molecular Biology, Hotchkiss Brain Institute, Alberta Children Hospital Research Institute, University of Calgary, Calgary T2N 4N1, Canada
| | - Ivana Kiroski
- Departments of Clinical Neurosciences, Cell Biology & Anatomy, and Biochemistry & Molecular Biology, Hotchkiss Brain Institute, Alberta Children Hospital Research Institute, University of Calgary, Calgary T2N 4N1, Canada
| | - G Campbell Teskey
- Department of Cell Biology & Anatomy, Hotchkiss Brain Institute, Alberta Children Hospital Research Institute, University of Calgary, Calgary T2N 4N1, Canada
| | - Jong M Rho
- Departments of Neurosciences & Pediatrics, University of California San Diego, Rady Children's Hospital San Diego, San Diego, CA 92123, USA
| | - Minh Dang Nguyen
- Departments of Clinical Neurosciences, Cell Biology & Anatomy, and Biochemistry & Molecular Biology, Hotchkiss Brain Institute, Alberta Children Hospital Research Institute, University of Calgary, Calgary T2N 4N1, Canada
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10
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Nakamura Y, Morrow DH, Nathanson AJ, Henley JM, Wilkinson KA, Moss SJ. Phosphorylation on Ser-359 of the α2 subunit in GABA type A receptors down-regulates their density at inhibitory synapses. J Biol Chem 2020; 295:12330-12342. [PMID: 32620552 PMCID: PMC7458806 DOI: 10.1074/jbc.ra120.014303] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 06/25/2020] [Indexed: 11/06/2022] Open
Abstract
GABA type A receptors (GABAARs) mediate fast synaptic inhibition and are trafficked to functionally diverse synapses. However, the precise molecular mechanisms that regulate the synaptic targeting of these receptors are unclear. Whereas it has been previously shown that phosphorylation events in α4, β, and γ subunits of GABAARs govern their function and trafficking, phosphorylation of other subunits has not yet been demonstrated. Here, we show that the α2 subunit of GABAARs is phosphorylated at Ser-359 and enables dynamic regulation of GABAAR binding to the scaffolding proteins gephyrin and collybistin. We initially identified Ser-359 phosphorylation by MS analysis, and additional experiments revealed that it is regulated by the activities of cAMP-dependent protein kinase (PKA) and the protein phosphatase 1 (PP1) and/or PP2A. GST-based pulldowns and coimmunoprecipitation experiments demonstrate preferential binding of both gephyrin and collybistin to WT and an S359A phosphonull variant, but not to an S359D phosphomimetic variant. Furthermore, the decreased capacity of the α2 S359D variant to bind collybistin and gephyrin decreased the density of synaptic α2-containing GABAAR clusters and caused an absence of α2 enrichment in the axon initial segment. These results suggest that PKA-mediated phosphorylation and PP1/PP2A-dependent dephosphorylation of the α2 subunit play a role in the dynamic regulation of GABAAR accumulation at inhibitory synapses, thereby regulating the strength of synaptic inhibition. The MS data have been deposited to ProteomeXchange, with the data set identifier PXD019597.
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Affiliation(s)
- Yasuko Nakamura
- School of Biochemistry, Centre for Synaptic Plasticity, University of Bristol, Bristol, United Kingdom
| | - Danielle H. Morrow
- Department of Neuroscience, Tufts University, School of Medicine, Boston, Massachusetts, USA
| | - Anna J. Nathanson
- Department of Neuroscience, Tufts University, School of Medicine, Boston, Massachusetts, USA
| | - Jeremy M. Henley
- School of Biochemistry, Centre for Synaptic Plasticity, University of Bristol, Bristol, United Kingdom
| | - Kevin A. Wilkinson
- School of Biochemistry, Centre for Synaptic Plasticity, University of Bristol, Bristol, United Kingdom
| | - Stephen J. Moss
- Department of Neuroscience, Tufts University, School of Medicine, Boston, Massachusetts, USA,Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom,For correspondence: S. J. Moss,
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11
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Nathanson AJ, Davies PA, Moss SJ. Inhibitory Synapse Formation at the Axon Initial Segment. Front Mol Neurosci 2019; 12:266. [PMID: 31749683 PMCID: PMC6848228 DOI: 10.3389/fnmol.2019.00266] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 10/17/2019] [Indexed: 11/28/2022] Open
Abstract
The axon initial segment (AIS) is the site of action potential (AP) initiation in most neurons and is thus a critical site in the regulation of neuronal excitability. Normal function within the discrete AIS compartment requires intricate molecular machinery to ensure the proper concentration and organization of voltage-gated and ligand-gated ion channels; in humans, dysfunction at the AIS due to channel mutations is commonly associated with epileptic disorders. In this review, we will examine the molecular mechanisms underlying the formation of the only synapses found at the AIS: synapses containing γ-aminobutyric type A receptors (GABAARs). GABAARs are heteropentamers assembled from 19 possible subunits and are the primary mediators of fast synaptic inhibition in the brain. Although the total GABAAR population is incredibly heterogeneous, only one specific GABAAR subtype—the α2-containing receptor—is enriched at the AIS. These AIS synapses are innervated by GABAergic chandelier cells, and this inhibitory signaling is thought to contribute to the tight control of AP firing. Here, we will summarize the progress made in understanding the regulation of GABAAR synapse formation, concentrating on post-translational modifications of subunits and on interactions with intracellular proteins. We will then discuss subtype-specific synapse formation, with a focus on synapses found at the AIS, and how these synapses influence neuronal excitation.
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Affiliation(s)
- Anna J Nathanson
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, United States
| | - Paul A Davies
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, United States
| | - Stephen J Moss
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, United States.,AstraZeneca Tufts Laboratory for Basic and Translational Neuroscience, Boston, MA, United States.,Department of Neuroscience, Physiology and Pharmacology, University College, London, United Kingdom
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12
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Contreras A, Hines DJ, Hines RM. Molecular Specialization of GABAergic Synapses on the Soma and Axon in Cortical and Hippocampal Circuit Function and Dysfunction. Front Mol Neurosci 2019; 12:154. [PMID: 31297048 PMCID: PMC6607995 DOI: 10.3389/fnmol.2019.00154] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 05/31/2019] [Indexed: 12/24/2022] Open
Abstract
The diversity of inhibitory interneurons allows for the coordination and modulation of excitatory principal cell firing. Interneurons that release GABA (γ-aminobutyric acid) onto the soma and axon exert powerful control by virtue of proximity to the site of action potential generation at the axon initial segment (AIS). Here, we review and examine the cellular and molecular regulation of soma and axon targeting GABAergic synapses in the cortex and hippocampus. We also describe their role in controlling network activity in normal and pathological states. Recent studies have demonstrated a specific role for postsynaptic dystroglycan in the formation and maintenance of cholecystokinin positive basket cell terminals contacting the soma, and postsynaptic collybistin in parvalbumin positive chandelier cell contacts onto the AIS. Unique presynaptic molecular contributors, LGI2 and FGF13, expressed in parvalbumin positive basket cells and chandelier cells, respectively, have also recently been identified. Mutations in the genes encoding proteins critical for somatic and AIS inhibitory synapses have been associated with human disorders of the nervous system. Dystroglycan dysfunction in some congenital muscular dystrophies is associated with developmental brain malformations, intellectual disability, and rare epilepsy. Collybistin dysfunction has been linked to hyperekplexia, epilepsy, intellectual disability, and developmental disorders. Both LGI2 and FGF13 mutations are implicated in syndromes with epilepsy as a component. Advancing our understanding of the powerful roles of somatic and axonic GABAergic contacts in controlling activity patterns in the cortex and hippocampus will provide insight into the pathogenesis of epilepsy and other nervous system disorders.
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Affiliation(s)
- April Contreras
- Department of Psychology, University of Nevada, Las Vegas, Las Vegas, NV, United States
| | - Dustin J Hines
- Department of Psychology, University of Nevada, Las Vegas, Las Vegas, NV, United States
| | - Rochelle M Hines
- Department of Psychology, University of Nevada, Las Vegas, Las Vegas, NV, United States
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13
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Yennawar M, White RS, Jensen FE. AMPA Receptor Dysregulation and Therapeutic Interventions in a Mouse Model of CDKL5 Deficiency Disorder. J Neurosci 2019; 39:4814-4828. [PMID: 30952813 PMCID: PMC6561688 DOI: 10.1523/jneurosci.2041-18.2019] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Revised: 03/13/2019] [Accepted: 03/27/2019] [Indexed: 01/28/2023] Open
Abstract
Pathogenic mutations in cyclin-dependent kinase-like 5 (CDKL5) result in CDKL5 deficiency disorder (CDD), a rare disease marked by early-life seizures, autistic behaviors, and intellectual disability. Although mouse models of CDD exhibit dendritic instability and alterations in synaptic scaffolding proteins, studies of glutamate receptor levels and function are limited. Here we used a novel mouse model of CDD, the Cdkl5R59X knock-in mouse (R59X), to investigate changes in synaptic glutamate receptor subunits and functional consequences. Male mice were used for all experiments to avoid the confounding effects of X-inactivation that would be present in female heterozygous mice. We showed that adult male R59X mice recapitulated the behavioral outcomes observed in other mouse models of CDD, including social deficits and memory and learning impairments, and exhibited decreased latency to seizure upon pentylenetetrazol administration. Furthermore, we observed a specific increase in GluA2-lacking α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid)-type glutamate receptors (AMPARs) in the adult R59X hippocampus, which is accompanied electrophysiologically by increased rectification ratio of AMPAR EPSCs and elevated early-phase long term potentiation (LTP). Finally, we showed that acute treatment with the GluA2-lacking AMPAR blocker IEM-1460 decreased AMPAR currents, and rescued social deficits, working memory impairments, and seizure behavior latency in R59X mice.SIGNIFICANCE STATEMENT CDKL5 deficiency disorder (CDD) is a rare disease marked by autistic-like behaviors, intellectual disability, and seizures. While synaptic dysfunction has been observed in mouse models of CDD, there is limited information on how synaptic alterations contribute to behavioral and functional changes in CDD. Here we reveal elevated hippocampal GluA2-lacking AMPAR expression in a novel mouse model of CDD that is accompanied by changes in synaptic AMPAR function and plasticity. We also show, for the first time, that acutely targeting GluA2-lacking AMPAR dysregulation rescues core synaptic and neurobehavioral deficits in CDD.
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MESH Headings
- Adult
- Animals
- Behavior, Animal
- Child, Preschool
- Disease Models, Animal
- Epileptic Syndromes/drug therapy
- Epileptic Syndromes/genetics
- Epileptic Syndromes/psychology
- Excitatory Postsynaptic Potentials/genetics
- Female
- Gene Knock-In Techniques
- Humans
- Learning Disabilities/genetics
- Learning Disabilities/psychology
- Male
- Memory Disorders/genetics
- Memory Disorders/psychology
- Mice
- Mice, Inbred C57BL
- Mice, Neurologic Mutants
- Mutation/genetics
- Protein Serine-Threonine Kinases/deficiency
- Protein Serine-Threonine Kinases/genetics
- Psychomotor Performance
- Receptors, AMPA/deficiency
- Receptors, AMPA/drug effects
- Receptors, AMPA/genetics
- Seizures/chemically induced
- Seizures/physiopathology
- Social Behavior
- Spasms, Infantile/drug therapy
- Spasms, Infantile/genetics
- Spasms, Infantile/psychology
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Affiliation(s)
| | - Rachel S White
- Department of Neurology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104
| | - Frances E Jensen
- Department of Neurology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104
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14
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Hines RM, Maric HM, Hines DJ, Modgil A, Panzanelli P, Nakamura Y, Nathanson AJ, Cross A, Deeb T, Brandon NJ, Davies P, Fritschy JM, Schindelin H, Moss SJ. Developmental seizures and mortality result from reducing GABA A receptor α2-subunit interaction with collybistin. Nat Commun 2018; 9:3130. [PMID: 30087324 PMCID: PMC6081406 DOI: 10.1038/s41467-018-05481-1] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Accepted: 07/05/2018] [Indexed: 01/08/2023] Open
Abstract
Fast inhibitory synaptic transmission is mediated by γ-aminobutyric acid type A receptors (GABAARs) that are enriched at functionally diverse synapses via mechanisms that remain unclear. Using isothermal titration calorimetry and complementary methods we demonstrate an exclusive low micromolar binding of collybistin to the α2-subunit of GABAARs. To explore the biological relevance of collybistin-α2-subunit selectivity, we generate mice with a mutation in the α2-subunit-collybistin binding region (Gabra2-1). The mutation results in loss of a distinct subset of inhibitory synapses and decreased amplitude of inhibitory synaptic currents. Gabra2-1 mice have a striking phenotype characterized by increased susceptibility to seizures and early mortality. Surviving Gabra2-1 mice show anxiety and elevations in electroencephalogram δ power, which are ameliorated by treatment with the α2/α3-selective positive modulator, AZD7325. Taken together, our results demonstrate an α2-subunit selective binding of collybistin, which plays a key role in patterned brain activity, particularly during development.
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Affiliation(s)
- Rochelle M Hines
- Department of Neuroscience, Tufts University School of Medicine, Boston, 02111, MA, USA.
- Department of Psychology, University of Nevada Las Vegas, Las Vegas, 89154, Ne, USA.
| | - Hans Michael Maric
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, D-97080, Germany
- Department of Biotechnology and Biophysics, Biocenter, University of Würzburg, Würzburg, D-97080, Germany
| | - Dustin J Hines
- Department of Neuroscience, Tufts University School of Medicine, Boston, 02111, MA, USA
- Department of Psychology, University of Nevada Las Vegas, Las Vegas, 89154, Ne, USA
| | - Amit Modgil
- Department of Neuroscience, Tufts University School of Medicine, Boston, 02111, MA, USA
| | - Patrizia Panzanelli
- Department of Neuroscience Rita Levi Montalcini, University of Turin, Turin, 10126, Italy
| | - Yasuko Nakamura
- Department of Neuroscience, Tufts University School of Medicine, Boston, 02111, MA, USA
| | - Anna J Nathanson
- Department of Neuroscience, Tufts University School of Medicine, Boston, 02111, MA, USA
| | - Alan Cross
- AstraZeneca Neuroscience iMED, Biotech Unit, Boston, 02451, MA, USA
| | - Tarek Deeb
- Department of Neuroscience, Tufts University School of Medicine, Boston, 02111, MA, USA
- AstraZeneca Tufts Laboratory for Basic and Translational Neuroscience, Boston, 02111, MA, USA
| | - Nicholas J Brandon
- AstraZeneca Neuroscience iMED, Biotech Unit, Boston, 02451, MA, USA
- AstraZeneca Tufts Laboratory for Basic and Translational Neuroscience, Boston, 02111, MA, USA
| | - Paul Davies
- Department of Neuroscience, Tufts University School of Medicine, Boston, 02111, MA, USA
| | - Jean-Marc Fritschy
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, 8057, Switzerland
- Center for Neuroscience Zurich, University of Zurich and ETH Zurich, Zurich, 8057, Switzerland
| | - Hermann Schindelin
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, D-97080, Germany
| | - Stephen J Moss
- Department of Neuroscience, Tufts University School of Medicine, Boston, 02111, MA, USA.
- AstraZeneca Tufts Laboratory for Basic and Translational Neuroscience, Boston, 02111, MA, USA.
- Department of Neuroscience, Physiology and Pharmacology, University College, London, WC1E 6BT, UK.
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15
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An Emerging Circuit Pharmacology of GABA A Receptors. Trends Pharmacol Sci 2018; 39:710-732. [PMID: 29903580 DOI: 10.1016/j.tips.2018.04.003] [Citation(s) in RCA: 127] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Revised: 03/23/2018] [Accepted: 04/17/2018] [Indexed: 12/21/2022]
Abstract
In the past 20 years we have learned a great deal about GABAA receptor (GABAAR) subtypes, and which behaviors are regulated or which drug effects are mediated by each subtype. However, the question of where GABAARs involved in specific drug effects and behaviors are located in the brain remains largely unanswered. We review here recent studies taking a circuit pharmacology approach to investigate the functions of GABAAR subtypes in specific brain circuits controlling fear, anxiety, learning, memory, reward, addiction, and stress-related behaviors. The findings of these studies highlight the complexity of brain inhibitory systems and the importance of taking a subtype-, circuit-, and neuronal population-specific approach to develop future therapeutic strategies using cell type-specific drug delivery.
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16
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Jiang Y, Xiao Y, Zhang X, Shu Y. Activation of axon initial segmental GABA A receptors inhibits action potential generation in neocortical GABAergic interneurons. Neuropharmacology 2018; 138:97-105. [PMID: 29883765 DOI: 10.1016/j.neuropharm.2018.05.026] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2018] [Revised: 05/14/2018] [Accepted: 05/20/2018] [Indexed: 10/16/2022]
Abstract
Ionotropic GABAA receptors expressing at the axon initial segment (AIS) of glutamatergic pyramidal cell (PC) in the cortex plays critical roles in regulating action potential generation. However, it remains unclear whether these receptors also express at the AIS of cortical GABAergic interneurons. In mouse prefrontal cortical slices, we performed experiments at the soma and AIS of the two most abundant GABAergic interneurons: parvalbumin (PV) and somatostatin (SST) positive neurons. Local application of GABA at the perisomatic axonal regions could evoke picrotoxin-sensitive currents with a reversal potential near the Cl- equilibrium potential. Puffing agonists to outside-out patches excised from AIS confirmed the expression of GABAA receptors. Further pharmacological experiments revealed that GABAA receptors in AIS of PV neurons contain α1 subunits, different from those containing α2/3 in AIS and α4 in axon trunk of layer-5 PCs. Cell-attached recording at the soma of PV and SST neurons revealed that the activation of AIS GABAA receptors inhibits the action potential generation induced by synaptic stimulation. Together, our results demonstrate that the AIS of PV and SST neurons express GABAA receptors with distinct subunit composition, which exert an inhibitory effect on neuronal excitability in these inhibitory interneurons.
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Affiliation(s)
- Yanbo Jiang
- Institute of Neuroscience and State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences and University of Chinese Academy of Sciences, Shanghai 200031, China
| | - Yujie Xiao
- State Key Laboratory of Cognitive Neuroscience and Learning, IDG/McGovern Institute for Brain Research, School of Brain and Cognitive Sciences, Beijing Normal University, Beijing 100875, China
| | - Xiaoxue Zhang
- State Key Laboratory of Cognitive Neuroscience and Learning, IDG/McGovern Institute for Brain Research, School of Brain and Cognitive Sciences, Beijing Normal University, Beijing 100875, China
| | - Yousheng Shu
- State Key Laboratory of Cognitive Neuroscience and Learning, IDG/McGovern Institute for Brain Research, School of Brain and Cognitive Sciences, Beijing Normal University, Beijing 100875, China.
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17
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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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18
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Babaev O, Piletti Chatain C, Krueger-Burg D. Inhibition in the amygdala anxiety circuitry. Exp Mol Med 2018; 50:1-16. [PMID: 29628509 PMCID: PMC5938054 DOI: 10.1038/s12276-018-0063-8] [Citation(s) in RCA: 172] [Impact Index Per Article: 28.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 01/25/2018] [Indexed: 01/09/2023] Open
Abstract
Inhibitory neurotransmission plays a key role in anxiety disorders, as evidenced by the anxiolytic effect of the benzodiazepine class of γ-aminobutyric acid (GABA) receptor agonists and the recent discovery of anxiety-associated variants in the molecular components of inhibitory synapses. Accordingly, substantial interest has focused on understanding how inhibitory neurons and synapses contribute to the circuitry underlying adaptive and pathological anxiety behaviors. A key element of the anxiety circuitry is the amygdala, which integrates information from cortical and thalamic sensory inputs to generate fear and anxiety-related behavioral outputs. Information processing within the amygdala is heavily dependent on inhibitory control, although the specific mechanisms by which amygdala GABAergic neurons and synapses regulate anxiety-related behaviors are only beginning to be uncovered. Here, we summarize the current state of knowledge and highlight open questions regarding the role of inhibition in the amygdala anxiety circuitry. We discuss the inhibitory neuron subtypes that contribute to the processing of anxiety information in the basolateral and central amygdala, as well as the molecular determinants, such as GABA receptors and synapse organizer proteins, that shape inhibitory synaptic transmission within the anxiety circuitry. Finally, we conclude with an overview of current and future approaches for converting this knowledge into successful treatment strategies for anxiety disorders.
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Affiliation(s)
- Olga Babaev
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Hermann-Rein-Str. 3, 37075, Göttingen, Germany
| | - Carolina Piletti Chatain
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Hermann-Rein-Str. 3, 37075, Göttingen, Germany
| | - Dilja Krueger-Burg
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Hermann-Rein-Str. 3, 37075, Göttingen, Germany.
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19
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20
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Lorenz-Guertin JM, Jacob TC. GABA type a receptor trafficking and the architecture of synaptic inhibition. Dev Neurobiol 2018; 78:238-270. [PMID: 28901728 PMCID: PMC6589839 DOI: 10.1002/dneu.22536] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 09/08/2017] [Accepted: 09/08/2017] [Indexed: 12/21/2022]
Abstract
Ubiquitous expression of GABA type A receptors (GABAA R) in the central nervous system establishes their central role in coordinating most aspects of neural function and development. Dysregulation of GABAergic neurotransmission manifests in a number of human health disorders and conditions that in certain cases can be alleviated by drugs targeting these receptors. Precise changes in the quantity or activity of GABAA Rs localized at the cell surface and at GABAergic postsynaptic sites directly impact the strength of inhibition. The molecular mechanisms constituting receptor trafficking to and from these compartments therefore dictate the efficacy of GABAA R function. Here we review the current understanding of how GABAA Rs traffic through biogenesis, plasma membrane transport, and degradation. Emphasis is placed on discussing novel GABAergic synaptic proteins, receptor and scaffolding post-translational modifications, activity-dependent changes in GABAA R confinement, and neuropeptide and neurosteroid mediated changes. We further highlight modern techniques currently advancing the knowledge of GABAA R trafficking and clinically relevant neurodevelopmental diseases connected to GABAergic dysfunction. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 78: 238-270, 2018.
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Affiliation(s)
- Joshua M Lorenz-Guertin
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, 15261
| | - Tija C Jacob
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, 15261
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21
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Jiang L, Ni H, Wang QY, Huang L, Zhao SD, Yu JD, Ge RJ. Dual face of axonal inhibitory inputs in the modulation of neuronal excitability in cortical pyramidal neurons. Neural Regen Res 2017; 12:1079-1085. [PMID: 28852389 PMCID: PMC5558486 DOI: 10.4103/1673-5374.211186] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Limited by the tiny structure of axons, the effects of these axonal hyperpolarizing inputs on neuronal activity have not been directly elucidated. Here, we imitated these processes by simultaneously recording the activities of the somas and proximal axons of cortical pyramidal neurons. We found that spikes and subthreshold potentials propagate between somas and axons with high fidelity. Furthermore, inhibitory inputs on axons have opposite effects on neuronal activity according to their temporal integration with upstream signals. Concurrent with somatic depolarization, inhibitory inputs on axons decrease neuronal excitability and impede spike generation. In addition, following action potentials, inhibitory inputs on an axon increase neuronal spike capacity and improve spike precision. These results indicate that inhibitory inputs on proximal axons have dual regulatory functions in neuronal activity (suppression or facilitation) according to neuronal network patterns.
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Affiliation(s)
- Lei Jiang
- Department of Pathophysiology, Bengbu Medical College, Bengbu, Anhui Province, China.,Department of General Surgery, The Second Affiliated Hospital of Bengbu Medical College, Bengbu, Anhui Province, China
| | - Hong Ni
- Department of Pathophysiology, Bengbu Medical College, Bengbu, Anhui Province, China
| | - Qi-Yi Wang
- Department of Physiology, Bengbu Medical College, Bengbu, Anhui Province, China
| | - Li Huang
- Department of Pathophysiology, Bengbu Medical College, Bengbu, Anhui Province, China
| | - Shi-di Zhao
- Department of Pathophysiology, Bengbu Medical College, Bengbu, Anhui Province, China
| | - Jian-Dong Yu
- Guangdong-Hongkong-Macau Institute of CNS Regeneration, Joint International Research Laboratory of CNS Regeneration, Ministry of Education, Jinan University, Guangzhou, Guangdong Province, China
| | - Rong-Jing Ge
- Department of Pathophysiology, Bengbu Medical College, Bengbu, Anhui Province, China
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