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Sui Y, Mortensen M, Yuan B, Nicholson MW, Smart TG, Jovanovic JN. GABA A receptors and neuroligin 2 synergize to promote synaptic adhesion and inhibitory synaptogenesis. Front Cell Neurosci 2024; 18:1423471. [PMID: 39100896 PMCID: PMC11295144 DOI: 10.3389/fncel.2024.1423471] [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: 04/25/2024] [Accepted: 07/02/2024] [Indexed: 08/06/2024] Open
Abstract
GABAA receptors (γ-aminobutyric acid-gated receptors type A; GABAARs), the major structural and functional postsynaptic components of inhibitory synapses in the mammalian brain, belong to a family of GABA-gated Cl-/HCO3 - ion channels. They are assembled as heteropentamers from a family of subunits including: α (1-6), β(1-3), γ(1-3), δ, ε, π, θ and ρ(1-3). GABAARs together with the postsynaptic adhesion protein Neuroligin 2 (NL2) and many other pre- and post-synaptic proteins guide the initiation and functional maturation of inhibitory GABAergic synapses. This study examined how GABAARs and NL2 interact with each other to initiate the formation of synapses. Two functionally distinct GABAAR subtypes, the synaptic type α2β2γ2-GABAARs versus extrasynaptic type α4β3δ-GABAARs were expressed in HEK293 cells alone or together with NL2 and co-cultured with striatal GABAergic medium spiny neurons to enable innervation of HEK293 cells by GABAergic axons. When expressed alone, only the synaptic α2β2γ2-GABAARs induced innervation of HEK293 cells. However, when GABAARs were co-expressed with NL2, the effect on synapse formation exceeded the individual effects of these proteins indicating a synergistic interaction, with α2β2γ2-GABAAR/NL2 showing a significantly greater synaptogenic activity than α4β3δ-GABAAR/NL2 or NL2 alone. To investigate the molecular basis of this interaction, different combinations of GABAAR subunits and NL2 were co-expressed, and the degree of innervation and synaptic activity assessed, revealing a key role of the γ2 subunit. In biochemical assays, the interaction between NL2 and α2β2γ2-GABAAR was established and mapped to the large intracellular domain of the γ2 subunit.
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Affiliation(s)
- Yusheng Sui
- Department of Pharmacology, School of Pharmacy, University College London, London, United Kingdom
| | - Martin Mortensen
- Department of Neuroscience, Physiology and Pharmacology, Division of Biosciences, University College London, London, United Kingdom
| | - Banghao Yuan
- Department of Pharmacology, School of Pharmacy, University College London, London, United Kingdom
| | - Martin W. Nicholson
- Department of Pharmacology, School of Pharmacy, University College London, London, United Kingdom
| | - Trevor G. Smart
- Department of Neuroscience, Physiology and Pharmacology, Division of Biosciences, University College London, London, United Kingdom
| | - Jasmina N. Jovanovic
- Department of Pharmacology, School of Pharmacy, University College London, London, United Kingdom
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2
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Menzikov SA, Zaichenko DM, Moskovtsev AA, Morozov SG, Kubatiev AA. Phenols and GABA A receptors: from structure and molecular mechanisms action to neuropsychiatric sequelae. Front Pharmacol 2024; 15:1272534. [PMID: 38303988 PMCID: PMC10831359 DOI: 10.3389/fphar.2024.1272534] [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: 08/04/2023] [Accepted: 01/03/2024] [Indexed: 02/03/2024] Open
Abstract
γ-Aminobutyric acid type A receptors (GABAARs) are members of the pentameric ligand-gated ion channel (pLGIC) family, which are widespread throughout the invertebrate and vertebrate central nervous system. GABAARs are engaged in short-term changes of the neuronal concentrations of chloride (Cl-) and bicarbonate (HCO3 -) ions by their passive permeability through the ion channel pore. GABAARs are regulated by various structurally diverse phenolic substances ranging from simple phenols to complex polyphenols. The wide chemical and structural variability of phenols suggest similar and different binding sites on GABAARs, allowing them to manifest themselves as activators, inhibitors, or allosteric ligands of GABAAR function. Interest in phenols is associated with their great potential for GABAAR modulation, but also with their subsequent negative or positive role in neurological and psychiatric disorders. This review focuses on the GABAergic deficit hypotheses during neurological and psychiatric disorders induced by various phenols. We summarize the structure-activity relationship of general phenol groups concerning their differential roles in the manifestation of neuropsychiatric symptoms. We describe and analyze the role of GABAAR subunits in manifesting various neuropathologies and the molecular mechanisms underlying their modulation by phenols. Finally, we discuss how phenol drugs can modulate GABAAR activity via desensitization and resensitization. We also demonstrate a novel pharmacological approach to treat neuropsychiatric disorders via regulation of receptor phosphorylation/dephosphorylation.
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Wenzel M, Huberfeld G, Grayden DB, de Curtis M, Trevelyan AJ. A debate on the neuronal origin of focal seizures. Epilepsia 2023; 64 Suppl 3:S37-S48. [PMID: 37183507 DOI: 10.1111/epi.17650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 04/26/2023] [Accepted: 05/12/2023] [Indexed: 05/16/2023]
Abstract
A critical question regarding how focal seizures start is whether we can identify particular cell classes that drive the pathological process. This was the topic for debate at the recent International Conference for Technology and Analysis of Seizures (ICTALS) meeting (July 2022, Bern, CH) that we summarize here. The debate has been fueled in recent times by the introduction of powerful new ways to manipulate subpopulations of cells in relative isolation, mostly using optogenetics. The motivation for resolving the debate is to identify novel targets for therapeutic interventions through a deeper understanding of the etiology of seizures.
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Affiliation(s)
- Michael Wenzel
- Department of Epileptology, University Hospital Bonn, University of Bonn, Bonn, Germany
| | - Gilles Huberfeld
- Neurology Department, Hopital Fondation Adolphe de Rothschild, Paris, France
- Center for Interdisciplinary Research in Biology (CIRB), College de France, CNRS, INSERM, Université PSL, Paris, France
| | - David B Grayden
- Department of Biomedical Engineering, The University of Melbourne, Melbourne, Victoria, Australia
- Department of Medicine, St Vincent's Hospital, The University of Melbourne, Melbourne, Victoria, Australia
- Graeme Clark Institute, The University of Melbourne, Melbourne, Victoria, Australia
| | - Marco de Curtis
- Epilepsy Unit, Fondazione I.R.C.C.S., Istituto Neurologico Carlo Besta, Milan, Italy
| | - Andrew J Trevelyan
- Newcastle University Biosciences Institute, Medical School, Framlington Place, Newcastle upon Tyne, UK
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Piatkevich KD, Boyden ES. Optogenetic control of neural activity: The biophysics of microbial rhodopsins in neuroscience. Q Rev Biophys 2023; 57:e1. [PMID: 37831008 DOI: 10.1017/s0033583523000033] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2023]
Abstract
Optogenetics, the use of microbial rhodopsins to make the electrical activity of targeted neurons controllable by light, has swept through neuroscience, enabling thousands of scientists to study how specific neuron types contribute to behaviors and pathologies, and how they might serve as novel therapeutic targets. By activating a set of neurons, one can probe what functions they can initiate or sustain, and by silencing a set of neurons, one can probe the functions they are necessary for. We here review the biophysics of these molecules, asking why they became so useful in neuroscience for the study of brain circuitry. We review the history of the field, including early thinking, early experiments, applications of optogenetics, pre-optogenetics targeted neural control tools, and the history of discovering and characterizing microbial rhodopsins. We then review the biophysical attributes of rhodopsins that make them so useful to neuroscience - their classes and structure, their photocycles, their photocurrent magnitudes and kinetics, their action spectra, and their ion selectivity. Our hope is to convey to the reader how specific biophysical properties of these molecules made them especially useful to neuroscientists for a difficult problem - the control of high-speed electrical activity, with great precision and ease, in the brain.
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Affiliation(s)
- Kiryl D Piatkevich
- School of Life Sciences, Westlake University, Hangzhou, China
- Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, China
- Institute of Basic Medical Sciences, Westlake Institute for Advanced Study, Hangzhou, China
| | - Edward S Boyden
- McGovern Institute and Koch Institute, Departments of Brain and Cognitive Sciences, Media Arts and Sciences, and Biological Engineering, K. Lisa Yang Center for Bionics and Center for Neurobiological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- Howard Hughes Medical Institute, Cambridge, MA, USA
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Zhong J, Dong J, Ruan W, Duan X. Potential Theranostic Roles of SLC4 Molecules in Human Diseases. Int J Mol Sci 2023; 24:15166. [PMID: 37894847 PMCID: PMC10606849 DOI: 10.3390/ijms242015166] [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: 08/29/2023] [Revised: 09/28/2023] [Accepted: 10/03/2023] [Indexed: 10/29/2023] Open
Abstract
The solute carrier family 4 (SLC4) is an important protein responsible for the transport of various ions across the cell membrane and mediating diverse physiological functions, such as the ion transporting function, protein-to-protein interactions, and molecular transduction. The deficiencies in SLC4 molecules may cause multisystem disease involving, particularly, the respiratory system, digestive, urinary, endocrine, hematopoietic, and central nervous systems. Currently, there are no effective strategies to treat these diseases. SLC4 proteins are also found to contribute to tumorigenesis and development, and some of them are regarded as therapeutic targets in quite a few clinical trials. This indicates that SLC4 proteins have potential clinical prospects. In view of their functional characteristics, there is a critical need to review the specific functions of bicarbonate transporters, their related diseases, and the involved pathological mechanisms. We summarize the diseases caused by the mutations in SLC4 family genes and briefly introduce the clinical manifestations of these diseases as well as the current treatment strategies. Additionally, we illustrate their roles in terms of the physiology and pathogenesis that has been currently researched, which might be the future therapeutic and diagnostic targets of diseases and a new direction for drug research and development.
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Affiliation(s)
| | | | | | - Xiaohong Duan
- State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, National Clinical Research Center for Oral Disease, Shaanxi Key Laboratory of Stomatology, Department of Oral Biology & Clinic of Oral Rare Diseases and Genetic Diseases, School of Stomatology, The Fourth Military Medical University, Xi’an 710032, China; (J.Z.); (J.D.); (W.R.)
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6
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Aikins AO, Farmer GE, Little JT, Cunningham JT. Effects of bile duct ligation on the inhibitory control of supraoptic vasopressin neurons. J Neuroendocrinol 2023; 35:e13312. [PMID: 37337093 PMCID: PMC10942741 DOI: 10.1111/jne.13312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 05/02/2023] [Accepted: 05/11/2023] [Indexed: 06/21/2023]
Abstract
Dilutional hyponatremia due to increased plasma arginine vasopressin (AVP) is associated with liver cirrhosis. However, plasma AVP remains elevated despite progressive hypoosmolality. This study investigated changes to inhibitory control of supraoptic nucleus (SON) AVP neurons during liver cirrhosis. Experiments were conducted with adult male Sprague-Dawley rats. Bile duct ligation was used as a model of chronic liver cirrhosis. An adeno-associated virus containing a construct with an AVP promoter and either green fluorescent protein (GFP) or a ratiometric chloride indicator, ClopHensorN, was bilaterally injected into the SON of rats. After 2 weeks, rats received either BDL or sham surgery, and liver cirrhosis was allowed to develop for 4 weeks. In vitro, loose patch recordings of action potentials were obtained from GFP-labeled and unlabeled SON neurons in response to a brief focal application of the GABAA agonist muscimol (100 μM). Changes to intracellular chloride ([Cl]i) following muscimol application were determined by changes to the fluorescence ratio of ClopHensorN. The contribution of cation chloride cotransporters NKCC1 and KCC2 to changes in intracellular chloride was investigated using their respective antagonists, bumetanide (BU, 10 μM) and VU0240551 (10 μM). Plasma osmolality and hematocrit were measured as a marker of dilutional hyponatremia. The results showed reduced or absent GABAA -mediated inhibition in a greater proportion of AVP neurons from BDL rats as compared to sham rats (100% inhibition in sham vs. 47% in BDL, p = .001). Muscimol application was associated with increased [Cl]i in most cells from BDL as compared to cells from sham rats (χ2 = 30.24, p < .001). NKCC1 contributed to the impaired inhibition observed in BDL rats (p < .001 BDL - BU vs. BDL + BU). The results show that impaired inhibition of SON AVP neurons and increased intracellular chloride contribute to the sustained dilutional hyponatremia in liver cirrhosis.
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Affiliation(s)
- Ato O Aikins
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas, USA
| | - George E Farmer
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas, USA
| | - Joel T Little
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas, USA
| | - J Thomas Cunningham
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas, USA
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Pressey JC, de Saint-Rome M, Raveendran VA, Woodin MA. Chloride transporters controlling neuronal excitability. Physiol Rev 2023; 103:1095-1135. [PMID: 36302178 DOI: 10.1152/physrev.00025.2021] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Synaptic inhibition plays a crucial role in regulating neuronal excitability, which is the foundation of nervous system function. This inhibition is largely mediated by the neurotransmitters GABA and glycine that activate Cl--permeable ion channels, which means that the strength of inhibition depends on the Cl- gradient across the membrane. In neurons, the Cl- gradient is primarily mediated by two secondarily active cation-chloride cotransporters (CCCs), NKCC1 and KCC2. CCC-mediated regulation of the neuronal Cl- gradient is critical for healthy brain function, as dysregulation of CCCs has emerged as a key mechanism underlying neurological disorders including epilepsy, neuropathic pain, and autism spectrum disorder. This review begins with an overview of neuronal chloride transporters before explaining the dependent relationship between these CCCs, Cl- regulation, and inhibitory synaptic transmission. We then discuss the evidence for how CCCs can be regulated, including by activity and their protein interactions, which underlie inhibitory synaptic plasticity. For readers who may be interested in conducting experiments on CCCs and neuronal excitability, we have included a section on techniques for estimating and recording intracellular Cl-, including their advantages and limitations. Although the focus of this review is on neurons, we also examine how Cl- is regulated in glial cells, which in turn regulate neuronal excitability through the tight relationship between this nonneuronal cell type and synapses. Finally, we discuss the relatively extensive and growing literature on how CCC-mediated neuronal excitability contributes to neurological disorders.
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Affiliation(s)
- Jessica C Pressey
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Miranda de Saint-Rome
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Vineeth A Raveendran
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Melanie A Woodin
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
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Menzikov SA, Zaichenko DM, Moskovtsev AA, Morozov SG, Kubatiev AA. Zinc Inhibits the GABA AR/ATPase during Postnatal Rat Development: The Role of Cysteine Residue. Int J Mol Sci 2023; 24:ijms24032764. [PMID: 36769085 PMCID: PMC9917249 DOI: 10.3390/ijms24032764] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 01/24/2023] [Accepted: 01/26/2023] [Indexed: 02/04/2023] Open
Abstract
Zinc ions (Zn2+) are concentrated in various brain regions and can act as a neuromodulator, targeting a wide spectrum of postsynaptic receptors and enzymes. Zn2+ inhibits the GABAARs, and its potency is profoundly affected by the subunit composition and neuronal developmental stage. Although the extracellular amino acid residues of the receptor's hetero-oligomeric structure are preferred for Zn2+ binding, there are intracellular sites that, in principle, could coordinate its potency. However, their role in modulating the receptor function during postembryonic development remains unclear. The GABAAR possesses an intracellular ATPase that enables the energy-dependent anion transport via a pore. Here, we propose a mechanistic and molecular basis for the inhibition of intracellular GABAAR/ATPase function by Zn2+ in neonatal and adult rats. The enzymes within the scope of GABAAR performance as Cl-ATPase and then as Cl-, HCO3-ATPase form during the first week of postnatal rat development. In addition, we have shown that the Cl-ATPase form belongs to the β1 subunit, whereas the β3 subunit preferably possesses the Cl-, HCO3-ATPase activity. We demonstrated that a Zn2+ with variable efficacy inhibits the GABAAR as well as the ATPase activities of immature or mature neurons. Using fluorescence recording in the cortical synaptoneurosomes (SNs), we showed a competitive association between Zn2+ and NEM in parallel changes both in the ATPase activity and the GABAAR-mediated Cl- and HCO3- fluxes. Finally, by site-directed mutagenesis, we identified in the M3 domain of β subunits the cysteine residue (C313) that is essential for the manifestation of Zn2+ potency.
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Bryson A, Reid C, Petrou S. Fundamental Neurochemistry Review: GABA A receptor neurotransmission and epilepsy: Principles, disease mechanisms and pharmacotherapy. J Neurochem 2023; 165:6-28. [PMID: 36681890 DOI: 10.1111/jnc.15769] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 12/12/2022] [Accepted: 01/04/2023] [Indexed: 01/23/2023]
Abstract
Epilepsy is a common neurological disorder associated with alterations of excitation-inhibition balance within brain neuronal networks. GABAA receptor neurotransmission is the most prevalent form of inhibitory neurotransmission and is strongly implicated in both the pathophysiology and treatment of epilepsy, serving as a primary target for antiseizure medications for over a century. It is now established that GABA exerts a multifaceted influence through an array of GABAA receptor subtypes that extends far beyond simply negating excitatory activity. As the role of GABAA neurotransmission within inhibitory circuits is elaborated, this will enable the development of precision therapies that correct the network dysfunction underlying epileptic pathology.
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Affiliation(s)
- Alexander Bryson
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria, Australia.,Department of Neurology, Austin Health, Heidelberg, Victoria, Australia
| | - Christopher Reid
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria, Australia
| | - Steven Petrou
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria, Australia.,Praxis Precision Medicines, Inc., Cambridge, Massachusetts, USA
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Shishkova VN, Nartsissov YR, Titova VY, Sheshegova EV. MOLECULAR MECHANISMS DEFINING APPLICATION OF GLYCINE AND ZINC COMBINATIONIN CORRECTION OF STRESS AND ANXIETY MAIN MANIFESTATIONS. PHARMACY & PHARMACOLOGY 2022. [DOI: 10.19163/2307-9266-2022-10-5-404-415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The aim of the work was to carry out a systematic analysis of the molecular mechanisms that determine the possibility of a combined use of amino acid glycine and zinc compounds for the treatment of patients with manifestations of stress and anxiety.Materials and methods. Information retrieval (Scopus, PubMed) and library (eLibrary) databases were used as research tools. In some cases, the ResearchGate application was applied for a semantic search. The analysis and generalization of references was carried out on the research topic, covering the period from 2000 to the present time.Results. It has been shown that amino acid glycine, along with gamma-aminobutyric acid (GABA), is a key neurotransmitter that regulates physiological inhibition processes in the central nervous system (CNS) by increasing transmembrane conductance in specific pentameric ligand-gated ion channels. The introduction of zinc ions can potentiate the opening of these receptors by increasing their affinity for glycine, resulting in an inhibitory processes increase in CNS neurons. The replenishment of the glycine and zinc combined deficiency is an important element in the correction of a post-stress dysfunction of the central nervous system. A balanced intake of zinc and glycine is essential for most people who experience daily effects of multiple stresses and anxiety. This combination is especially useful for the people experiencing a state of chronic psycho-emotional stress and maladaptation, including those who have a difficulty in falling asleep.Conclusion. A balanced maintenance of the zinc and glycine concentration in the body of a healthy person leads to the development of a stable anti-anxiety effect, which is accompanied by the normalization of the sleep-wake rhythm, which makes it possible to have a good rest without any loss of working efficiency after waking up.
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Affiliation(s)
- V. N. Shishkova
- National Medical Research Center for Therapy and Preventive Medicine;
Evdokimov Moscow State Medical and Dental University
| | - Y. R. Nartsissov
- Institute of Cytochemistry and Molecular Pharmacology;
Biomedical Research Group, BiDiPharma GmbH
| | - V. Y. Titova
- Institute of Cytochemistry and Molecular Pharmacology
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Sinha AS, Wang T, Watanabe M, Hosoi Y, Sohara E, Akita T, Uchida S, Fukuda A. WNK3 kinase maintains neuronal excitability by reducing inwardly rectifying K+ conductance in layer V pyramidal neurons of mouse medial prefrontal cortex. Front Mol Neurosci 2022; 15:856262. [PMID: 36311015 PMCID: PMC9613442 DOI: 10.3389/fnmol.2022.856262] [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: 01/17/2022] [Accepted: 09/22/2022] [Indexed: 11/13/2022] Open
Abstract
The with-no-lysine (WNK) family of serine-threonine kinases and its downstream kinases of STE20/SPS1-related proline/alanine-rich kinase (SPAK) and oxidative stress-responsive kinase-1 (OSR1) may regulate intracellular Cl− homeostasis through phosphorylation of cation-Cl− co-transporters. WNK3 is expressed in fetal and postnatal brains, and its expression level increases during development. Its roles in neurons, however, remain uncertain. Using WNK3 knockout (KO) mice, we investigated the role of WNK3 in the regulation of the intracellular Cl− concentration ([Cl−]i) and the excitability of layer V pyramidal neurons in the medial prefrontal cortex (mPFC). Gramicidin-perforated patch-clamp recordings in neurons from acute slice preparation at the postnatal day 21 indicated a significantly depolarized reversal potential for GABAA receptor-mediated currents by 6 mV, corresponding to the higher [Cl−]i level by ~4 mM in KO mice than in wild-type littermates. However, phosphorylation levels of SPAK and OSR1 and those of neuronal Na+-K+-2Cl− co-transporter NKCC1 and K+-Cl− co-transporter KCC2 did not significantly differ between KO and wild-type mice. Meanwhile, the resting membrane potential of neurons was more hyperpolarized by 7 mV, and the minimum stimulus current necessary for firing induction was increased in KO mice. These were due to an increased inwardly rectifying K+ (IRK) conductance, mediated by classical inwardly rectifying (Kir) channels, in KO neurons. The introduction of an active form of WNK3 into the recording neurons reversed these changes. The potential role of KCC2 function in the observed changes of KO neurons was investigated by applying a selective KCC2 activator, CLP290. This reversed the enhanced IRK conductance in KO neurons, indicating that both WNK3 and KCC2 are intimately linked in the regulation of resting K+ conductance. Evaluation of synaptic properties revealed that the frequency of miniature excitatory postsynaptic currents (mEPSCs) was reduced, whereas that of inhibitory currents (mIPSCs) was slightly increased in KO neurons. Together, the impact of these developmental changes on the membrane and synaptic properties was manifested as behavioral deficits in pre-pulse inhibition, a measure of sensorimotor gating involving multiple brain regions including the mPFC, in KO mice. Thus, the basal function of WNK3 would be the maintenance and/or development of both intrinsic and synaptic excitabilities.
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Affiliation(s)
- Adya Saran Sinha
- Department of Neurophysiology, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Tianying Wang
- Department of Neurophysiology, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Miho Watanabe
- Department of Neurophysiology, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Yasushi Hosoi
- Department of Neurophysiology, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Eisei Sohara
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Tenpei Akita
- Department of Neurophysiology, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Shinichi Uchida
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Atsuo Fukuda
- Department of Neurophysiology, Hamamatsu University School of Medicine, Hamamatsu, Japan
- *Correspondence: Atsuo Fukuda
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12
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Dietz RM, Dingman AL, Herson PS. Cerebral ischemia in the developing brain. J Cereb Blood Flow Metab 2022; 42:1777-1796. [PMID: 35765984 PMCID: PMC9536116 DOI: 10.1177/0271678x221111600] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Revised: 04/29/2022] [Accepted: 05/27/2022] [Indexed: 11/16/2022]
Abstract
Brain ischemia affects all ages, from neonates to the elderly population, and is a leading cause of mortality and morbidity. Multiple preclinical rodent models involving different ages have been developed to investigate the effect of ischemia during different times of key brain maturation events. Traditional models of developmental brain ischemia have focused on rodents at postnatal day 7-10, though emerging models in juvenile rodents (postnatal days 17-25) indicate that there may be fundamental differences in neuronal injury and functional outcomes following focal or global cerebral ischemia at different developmental ages, as well as in adults. Here, we consider the timing of injury in terms of excitation/inhibition balance, oxidative stress, inflammatory responses, blood brain barrier integrity, and white matter injury. Finally, we review translational strategies to improve function after ischemic brain injury, including new ideas regarding neurorestoration, or neural repair strategies that restore plasticity, at delayed time points after ischemia.
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Affiliation(s)
- Robert M Dietz
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO, USA
- Department of Anesthesiology, University of Colorado School of Medicine, Aurora, CO, USA
- Neuronal Injury Program, University of Colorado School of Medicine, Aurora, CO, USA
| | - Andra L Dingman
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO, USA
- Neuronal Injury Program, University of Colorado School of Medicine, Aurora, CO, USA
| | - Paco S Herson
- Department of Neurological Surgery, The Ohio State University College of Medicine, Columbus, OH, USA
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13
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Currin CB, Raimondo JV. Computational models reveal how chloride dynamics determine the optimal distribution of inhibitory synapses to minimise dendritic excitability. PLoS Comput Biol 2022; 18:e1010534. [PMID: 36149893 PMCID: PMC9534446 DOI: 10.1371/journal.pcbi.1010534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 10/05/2022] [Accepted: 09/01/2022] [Indexed: 12/05/2022] Open
Abstract
Many neurons in the mammalian central nervous system have complex dendritic arborisations and active dendritic conductances that enable these cells to perform sophisticated computations. How dendritically targeted inhibition affects local dendritic excitability is not fully understood. Here we use computational models of branched dendrites to investigate where GABAergic synapses should be placed to minimise dendritic excitability over time. To do so, we formulate a metric we term the “Inhibitory Level” (IL), which quantifies the effectiveness of synaptic inhibition for reducing the depolarising effect of nearby excitatory input. GABAergic synaptic inhibition is dependent on the reversal potential for GABAA receptors (EGABA), which is primarily set by the transmembrane chloride ion (Cl-) concentration gradient. We, therefore, investigated how variable EGABA and dynamic chloride affects dendritic inhibition. We found that the inhibitory effectiveness of dendritic GABAergic synapses combines at an encircled branch junction. The extent of this inhibitory accumulation is dependent on the number of branches and location of synapses but is independent of EGABA. This inhibitory accumulation occurs even for very distally placed inhibitory synapses when they are hyperpolarising–but not when they are shunting. When accounting for Cl- fluxes and dynamics in Cl- concentration, we observed that Cl- loading is detrimental to inhibitory effectiveness. This enabled us to determine the most inhibitory distribution of GABAergic synapses which is close to–but not at–a shared branch junction. This distribution balances a trade-off between a stronger combined inhibitory influence when synapses closely encircle a branch junction with the deleterious effects of increased Cl- by loading that occurs when inhibitory synapses are co-located. Dendritic branches allow for a rich repertoire of computational capabilities for neurons within the brain. Inhibitory synaptic inputs, which utilise the neurotransmitter GABA, refine and enhance dendritic computations. They are traditionally viewed with regards to their inhibitory effect on action potential generation at the neuronal cell body. Here, we studied the local effects of inhibitory synapses on excitability in dendrites. We also considered the dynamic nature of inhibition that deteriorates the longer it is active due to intracellular chloride ion loading. The central goal of our investigation was to find the best locations for multiple inhibitory synapses to maximise their combined inhibitory effectiveness on nearby excitation in the dendritic tree. We found that the optimal distribution is when inhibitory synapses closely encircle a branch junction, without being co-located at the junction itself. This maximises how their inhibitory influence combines whilst minimising the deleterious effects of chloride loading.
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Affiliation(s)
- Christopher Brian Currin
- Division of Cell Biology, Department of Human Biology, Neuroscience Institute and Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
- * E-mail:
| | - Joseph Valentino Raimondo
- Division of Cell Biology, Department of Human Biology, Neuroscience Institute and Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
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14
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Plasticity of neuronal excitability and synaptic balance in the anterior nucleus of paraventricular thalamus after nerve injury. Brain Res Bull 2022; 188:1-10. [PMID: 35850188 DOI: 10.1016/j.brainresbull.2022.07.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 06/20/2022] [Accepted: 07/14/2022] [Indexed: 11/22/2022]
Abstract
The anterior nucleus of the paraventricular thalamus (aPVT) integrates various synaptic inputs and conveys information to the downstream brain regions for arousal and pain regulation. Recent studies have indicated that the PVT plays a crucial role in the regulation of chronic pain, but the plasticity mechanism of neuronal excitability and synaptic inputs for aPVT neurons in neuropathic pain remains unclear. Here, we report that spinal nerve ligation (SNL) significantly increased the neuronal excitability and reset the excitatory/inhibitory (E/I) synaptic inputs ratio of aPVT neurons in mice. SNL significantly increased the membrane input resistance, firing frequency, and the half-width of action potential. Additionally, SNL enlarged the area of afterdepolarization and prolonged the rebound low-threshold spike following a hyperpolarized current injection. Further results indicate that an inwardly rectifying current density was decreased in SNL animals. SNL also decreased the amplitude, but not the frequency of spontaneous excitatory postsynaptic currents (sEPSCs), nor the amplitude or frequency of spontaneous inhibitory postsynaptic currents (sIPSCs) of aPVT neurons. Moreover, SNL disrupted the E/I synaptic ratio, caused a decrease in weighted tau and half-width of averaged sIPSCs, but did not change these physiological properties of averaged sEPSCs. Finally, pharmacological activation of the GABAA receptor at aPVT could effective relieve SNL-induced mechanical allodynia in mice. These results reveal the plasticity of intrinsic neuronal excitability and E/I synaptic balance in the aPVT neurons after nerve injury and it may play an important role in the development of pain sensitization.
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15
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Prael III FJ, Kim K, Du Y, Spitznagel BD, Sulikowski GA, Delpire E, Weaver CD. Discovery of Small Molecule KCC2 Potentiators Which Attenuate In Vitro Seizure-Like Activity in Cultured Neurons. Front Cell Dev Biol 2022; 10:912812. [PMID: 35813195 PMCID: PMC9263442 DOI: 10.3389/fcell.2022.912812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Accepted: 06/02/2022] [Indexed: 01/14/2023] Open
Abstract
KCC2 is a K+-Cl- cotransporter that is expressed in neurons throughout the central nervous system. Deficits in KCC2 activity have been implicated in a variety of neurological disorders, including epilepsy, chronic pain, autism spectrum disorders, and Rett syndrome. Therefore, it has been hypothesized that pharmacological potentiation of KCC2 activity could provide a treatment for these disorders. To evaluate the therapeutic potential of pharmacological KCC2 potentiation, drug-like, selective KCC2 potentiators are required. Unfortunately, the lack of such tools has greatly hampered the investigation of the KCC2 potentiation hypothesis. Herein, we describe the discovery and characterization of a new class of small-molecule KCC2 potentiator. This newly discovered class exhibits KCC2-dependent activity and a unique mechanistic profile relative to previously reported small molecules. Furthermore, we demonstrate that KCC2 potentiation by this new class of KCC2 potentiator attenuates seizure-like activity in neuronal-glial co-cultures. Together, our results provide evidence that pharmacological KCC2 potentiation, by itself, is sufficient to attenuate neuronal excitability in an in vitro model that is sensitive to anti-epileptic drugs. Our findings and chemical tools are important for evaluating the promise of KCC2 as a therapeutic target and could lay a foundation for the development of KCC2-directed therapeutics for multiple neurological disorders.
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Affiliation(s)
- Francis J. Prael III
- Department of Pharmacology, Vanderbilt University, Nashville, TN, United States,Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN, United States
| | - Kwangho Kim
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN, United States,Department of Chemistry, Vanderbilt University, Nashville, TN, United States
| | - Yu Du
- Department of Pharmacology, Vanderbilt University, Nashville, TN, United States
| | | | - Gary A. Sulikowski
- Department of Pharmacology, Vanderbilt University, Nashville, TN, United States,Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN, United States,Department of Chemistry, Vanderbilt University, Nashville, TN, United States
| | - Eric Delpire
- Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, TN, United States
| | - C. David Weaver
- Department of Pharmacology, Vanderbilt University, Nashville, TN, United States,Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN, United States,Department of Chemistry, Vanderbilt University, Nashville, TN, United States,*Correspondence: C. David Weaver,
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16
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Menzikov SA, Zaichenko DM, Moskovtsev AA, Morozov SG, Kubatiev AA. Physiological Role of ATPase for GABA A Receptor Resensitization. Int J Mol Sci 2022; 23:ijms23105320. [PMID: 35628132 PMCID: PMC9141714 DOI: 10.3390/ijms23105320] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 05/03/2022] [Accepted: 05/07/2022] [Indexed: 02/01/2023] Open
Abstract
γ-Aminobutyric acid type A receptors (GABAARs) mediate primarily inhibitory synaptic transmission in the central nervous system. Following fast-paced activation, which provides the selective flow of mainly chloride (Cl−) and less bicarbonate (HCO3−) ions via the pore, these receptors undergo desensitization that is paradoxically prevented by the process of their recovery, referred to as resensitization. To clarify the mechanism of resensitization, we used the cortical synaptoneurosomes from the rat brain and HEK 293FT cells. Here, we describe the effect of γ-phosphate analogues (γPAs) that mimic various states of ATP hydrolysis on GABAAR-mediated Cl− and HCO3− fluxes in response to the first and repeated application of the agonist. We found that depending on the presence of bicarbonate, opened and desensitized states of the wild or chimeric GABAARs had different sensitivities to γPAs. This study presents the evidence that recovery of neuronal Cl− and HCO3− concentrations after desensitization is accompanied by a change in the intracellular ATP concentration via ATPase performance. The transition between the desensitization and resensitization states was linked to changes in both conformation and phosphorylation. In addition, the chimeric β3 isoform did not exhibit the desensitization of the GABAAR-mediated Cl− influx but only the resensitization. These observations lend a new physiological significance to the β3 subunit in the manifestation of GABAAR resensitization.
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Affiliation(s)
- Sergey A. Menzikov
- Institute of General Pathology and Pathophysiology, Russian Academy of Sciences, 8, Baltiyskaya St., 125315 Moscow, Russia; (D.M.Z.); (A.A.M.); (S.G.M.); (A.A.K.)
- Correspondence: ; Tel.: +7-(499)-151-1756; Fax: +7-(495)-601-2366
| | - Danila M. Zaichenko
- Institute of General Pathology and Pathophysiology, Russian Academy of Sciences, 8, Baltiyskaya St., 125315 Moscow, Russia; (D.M.Z.); (A.A.M.); (S.G.M.); (A.A.K.)
| | - Aleksey A. Moskovtsev
- Institute of General Pathology and Pathophysiology, Russian Academy of Sciences, 8, Baltiyskaya St., 125315 Moscow, Russia; (D.M.Z.); (A.A.M.); (S.G.M.); (A.A.K.)
- Russian Medical Academy of Postdoctoral Education, Federal State Budgetary Educational Institution of Further Professional Education of the Ministry of Healthcare of the Russian Federation, 2/1, Barrykadnaya St., 125993 Moscow, Russia
| | - Sergey G. Morozov
- Institute of General Pathology and Pathophysiology, Russian Academy of Sciences, 8, Baltiyskaya St., 125315 Moscow, Russia; (D.M.Z.); (A.A.M.); (S.G.M.); (A.A.K.)
| | - Aslan A. Kubatiev
- Institute of General Pathology and Pathophysiology, Russian Academy of Sciences, 8, Baltiyskaya St., 125315 Moscow, Russia; (D.M.Z.); (A.A.M.); (S.G.M.); (A.A.K.)
- Russian Medical Academy of Postdoctoral Education, Federal State Budgetary Educational Institution of Further Professional Education of the Ministry of Healthcare of the Russian Federation, 2/1, Barrykadnaya St., 125993 Moscow, Russia
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17
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Why won't it stop? The dynamics of benzodiazepine resistance in status epilepticus. Nat Rev Neurol 2022; 18:428-441. [PMID: 35538233 DOI: 10.1038/s41582-022-00664-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/19/2022] [Indexed: 11/08/2022]
Abstract
Status epilepticus is a life-threatening neurological emergency that affects both adults and children. Approximately 36% of episodes of status epilepticus do not respond to the current preferred first-line treatment, benzodiazepines. The proportion of episodes that are refractory to benzodiazepines is higher in low-income and middle-income countries (LMICs) than in high-income countries (HICs). Evidence suggests that longer episodes of status epilepticus alter brain physiology, thereby contributing to the emergence of benzodiazepine resistance. Such changes include alterations in GABAA receptor function and in the transmembrane gradient for chloride, both of which erode the ability of benzodiazepines to enhance inhibitory synaptic signalling. Often, current management guidelines for status epilepticus do not account for these duration-related changes in pathophysiology, which might differentially impact individuals in LMICs, where the average time taken to reach medical attention is longer than in HICs. In this Perspective article, we aim to combine clinical insights and the latest evidence from basic science to inspire a new, context-specific approach to efficiently managing status epilepticus.
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18
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Dohm-Hansen S, Donoso F, Lucassen PJ, Clarke G, Nolan YM. The gut microbiome and adult hippocampal neurogenesis: A new focal point for epilepsy? Neurobiol Dis 2022; 170:105746. [DOI: 10.1016/j.nbd.2022.105746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2021] [Revised: 04/13/2022] [Accepted: 04/29/2022] [Indexed: 02/07/2023] Open
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19
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Lodovichi C, Ratto GM, Trevelyan AJ, Arosio D. Genetically encoded sensors for Chloride concentration. J Neurosci Methods 2022; 368:109455. [PMID: 34952088 DOI: 10.1016/j.jneumeth.2021.109455] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 12/11/2021] [Accepted: 12/18/2021] [Indexed: 12/12/2022]
Abstract
Insights into chloride regulation in neurons have come slowly, but they are likely to be critical for our understanding of how the brain works. The reason is that the intracellular Cl- level ([Cl-]i) is the key determinant of synaptic inhibitory function, and this in turn dictates all manner of neuronal network function. The true impact on the network will only be apparent, however, if Cl- is measured at many locations at once (multiple neurons, and also across the subcellular compartments of single neurons), which realistically, can only be achieved using imaging. The development of genetically-encoded anion biosensors (GABs) brings the additional benefit that Cl- imaging may be done in identified cell-classes and hopefully in subcellular compartments. Here, we describe the historical background and motivation behind the development of these sensors and how they have been used so far. There are, however, still major limitations for their use, the most important being the fact that all GABs are sensitive to both pH and Cl-. Disambiguating the two signals has proved a major challenge, but there are potential solutions; notable among these is ClopHensor, which has now been developed for in vivo measurements of both ion species. We also speculate on how these biosensors may yet be improved, and how this could advance our understanding of Cl- regulation and its impact on brain function.
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Affiliation(s)
- Claudia Lodovichi
- Neuroscience Institute-CNR, Depart. Biomedical Sciences, Unipd, Padova, Veneto Institute of Molecular Medicine, Padova Neuroscience Center, Padova, Italy.
| | - Gian Michele Ratto
- National Enterprise for nanoScience and nanoTechnology (NEST), Istituto Nanoscienze, Consiglio Nazionale delle Ricerche (CNR) and Scuola Normale Superiore Pisa, 56127 Pisa, Italy
| | - Andrew J Trevelyan
- Newcastle University Biosciences Institute, Medical School, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
| | - Daniele Arosio
- Consiglio Nazionale delle Ricerche (CNR), Istituto di Biofisica, 38123 Trento, Italy.
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20
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Warm D, Schroer J, Sinning A. Gabaergic Interneurons in Early Brain Development: Conducting and Orchestrated by Cortical Network Activity. Front Mol Neurosci 2022; 14:807969. [PMID: 35046773 PMCID: PMC8763242 DOI: 10.3389/fnmol.2021.807969] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 12/06/2021] [Indexed: 01/22/2023] Open
Abstract
Throughout early phases of brain development, the two main neural signaling mechanisms—excitation and inhibition—are dynamically sculpted in the neocortex to establish primary functions. Despite its relatively late formation and persistent developmental changes, the GABAergic system promotes the ordered shaping of neuronal circuits at the structural and functional levels. Within this frame, interneurons participate first in spontaneous and later in sensory-evoked activity patterns that precede cortical functions of the mature brain. Upon their subcortical generation, interneurons in the embryonic brain must first orderly migrate to and settle in respective target layers before they can actively engage in cortical network activity. During this process, changes at the molecular and synaptic level of interneurons allow not only their coordinated formation but also the pruning of connections as well as excitatory and inhibitory synapses. At the postsynaptic site, the shift of GABAergic signaling from an excitatory towards an inhibitory response is required to enable synchronization within cortical networks. Concomitantly, the progressive specification of different interneuron subtypes endows the neocortex with distinct local cortical circuits and region-specific modulation of neuronal firing. Finally, the apoptotic process further refines neuronal populations by constantly maintaining a controlled ratio of inhibitory and excitatory neurons. Interestingly, many of these fundamental and complex processes are influenced—if not directly controlled—by electrical activity. Interneurons on the subcellular, cellular, and network level are affected by high frequency patterns, such as spindle burst and gamma oscillations in rodents and delta brushes in humans. Conversely, the maturation of interneuron structure and function on each of these scales feeds back and contributes to the generation of cortical activity patterns that are essential for the proper peri- and postnatal development. Overall, a more precise description of the conducting role of interneurons in terms of how they contribute to specific activity patterns—as well as how specific activity patterns impinge on their maturation as orchestra members—will lead to a better understanding of the physiological and pathophysiological development and function of the nervous system.
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21
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Savardi A, Borgogno M, De Vivo M, Cancedda L. Pharmacological tools to target NKCC1 in brain disorders. Trends Pharmacol Sci 2021; 42:1009-1034. [PMID: 34620512 DOI: 10.1016/j.tips.2021.09.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 08/27/2021] [Accepted: 09/08/2021] [Indexed: 02/06/2023]
Abstract
The chloride importer NKCC1 and the chloride exporter KCC2 are key regulators of neuronal chloride concentration. A defective NKCC1/KCC2 expression ratio is associated with several brain disorders. Preclinical/clinical studies have shown that NKCC1 inhibition by the United States FDA-approved diuretic bumetanide is a potential therapeutic strategy in preclinical/clinical studies of multiple neurological conditions. However, bumetanide has poor brain penetration and causes unwanted diuresis by inhibiting NKCC2 in the kidney. To overcome these issues, a growing number of studies have reported more brain-penetrating and/or selective bumetanide prodrugs, analogs, and new molecular entities. Here, we review the evidence for NKCC1 pharmacological inhibition as an effective strategy to manage neurological disorders. We also discuss the advantages and limitations of bumetanide repurposing and the benefits and risks of new NKCC1 inhibitors as therapeutic agents for brain disorders.
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Affiliation(s)
- Annalisa Savardi
- Brain Development and Disease Laboratory, Istituto Italiano di Tecnologia, via Morego, 30, 16163 Genoa, Italy; Dulbecco Telethon Institute, 00185 Rome, Italy; Molecular Modeling and Drug Discovery Laboratory, Istituto Italiano di Tecnologia, via Morego, 30, 16163 Genoa, Italy
| | - Marco Borgogno
- Molecular Modeling and Drug Discovery Laboratory, Istituto Italiano di Tecnologia, via Morego, 30, 16163 Genoa, Italy
| | - Marco De Vivo
- Molecular Modeling and Drug Discovery 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; Dulbecco Telethon Institute, 00185 Rome, Italy.
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22
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Lamtahri R, Hazime M, Gowing EK, Nagaraja RY, Maucotel J, Alasoadura M, Quilichini PP, Lehongre K, Lefranc B, Gach-Janczak K, Marcher AB, Mandrup S, Vaudry D, Clarkson AN, Leprince J, Chuquet J. The Gliopeptide ODN, a Ligand for the Benzodiazepine Site of GABA A Receptors, Boosts Functional Recovery after Stroke. J Neurosci 2021; 41:7148-7159. [PMID: 34210784 PMCID: PMC8372017 DOI: 10.1523/jneurosci.2255-20.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 12/14/2020] [Accepted: 03/25/2021] [Indexed: 11/21/2022] Open
Abstract
Following stroke, the survival of neurons and their ability to reestablish connections is critical to functional recovery. This is strongly influenced by the balance between neuronal excitation and inhibition. In the acute phase of experimental stroke, lethal hyperexcitability can be attenuated by positive allosteric modulation of GABAA receptors (GABAARs). Conversely, in the late phase, negative allosteric modulation of GABAAR can correct the suboptimal excitability and improves both sensory and motor recovery. Here, we hypothesized that octadecaneuropeptide (ODN), an endogenous allosteric modulator of the GABAAR synthesized by astrocytes, influences the outcome of ischemic brain tissue and subsequent functional recovery. We show that ODN boosts the excitability of cortical neurons, which makes it deleterious in the acute phase of stroke. However, if delivered after day 3, ODN is safe and improves motor recovery over the following month in two different paradigms of experimental stroke in mice. Furthermore, we bring evidence that, during the subacute period after stroke, the repairing cortex can be treated with ODN by means of a single hydrogel deposit into the stroke cavity.SIGNIFICANCE STATEMENT Stroke remains a devastating clinical challenge because there is no efficient therapy to either minimize neuronal death with neuroprotective drugs or to enhance spontaneous recovery with neurorepair drugs. Around the brain damage, the peri-infarct cortex can be viewed as a reservoir of plasticity. However, the potential of wiring new circuits in these areas is restrained by a chronic excess of GABAergic inhibition. Here we show that an astrocyte-derived peptide, can be used as a delayed treatment, to safely correct cortical excitability and facilitate sensorimotor recovery after stroke.
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Affiliation(s)
- Rhita Lamtahri
- Normandie Université, UNIROUEN, Institut National de la Santé et de la Recherche Médicale U1239, Neuronal and Neuroendocrine Differentiation and Communication, Rouen, France
| | - Mahmoud Hazime
- Normandie Université, UNIROUEN, Institut National de la Santé et de la Recherche Médicale U1239, Neuronal and Neuroendocrine Differentiation and Communication, Rouen, France
| | - Emma K Gowing
- Department of Anatomy, Brain Health Research Centre and Brain Research New Zealand, University of Otago, Dunedin, 76000, 9054, New Zealand
| | - Raghavendra Y Nagaraja
- Department of Anatomy, Brain Health Research Centre and Brain Research New Zealand, University of Otago, Dunedin, 76000, 9054, New Zealand
| | - Julie Maucotel
- Normandie Université, UNIROUEN, Animal Facility, Rouen, 76000, France
| | - Michael Alasoadura
- Normandie Université, UNIROUEN, Institut National de la Santé et de la Recherche Médicale U1239, Neuronal and Neuroendocrine Differentiation and Communication, Rouen, France
| | | | - Katia Lehongre
- Inserm U 1127, Centre National de la Recherche Scientifique Unite Mixte de Recherche 7225, Sorbonne Universités, UPMC Univ Paris 06 Unite Mixte de Recherche S 1127, Institut du Cerveau et de la Moelle épinière, ICM, Paris, F-75013, France
| | - Benjamin Lefranc
- Normandie Université, UNIROUEN, Institut National de la Santé et de la Recherche Médicale U1239, Neuronal and Neuroendocrine Differentiation and Communication, Rouen, France
- Institute for Research and Innovation in Biomedicine, Normandie Université, PRIMACEN, Rouen, 76000, France
| | - Katarzyna Gach-Janczak
- Normandie Université, UNIROUEN, Institut National de la Santé et de la Recherche Médicale U1239, Neuronal and Neuroendocrine Differentiation and Communication, Rouen, France
- Department of Biomolecular Chemistry, Medicinal University of Łódź, Łódź, 90-137, Poland
| | - Ann-Britt Marcher
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, 5230, Denmark
| | - Susanne Mandrup
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, 5230, Denmark
| | - David Vaudry
- Normandie Université, UNIROUEN, Institut National de la Santé et de la Recherche Médicale U1239, Neuronal and Neuroendocrine Differentiation and Communication, Rouen, France
- Institute for Research and Innovation in Biomedicine, Normandie Université, PRIMACEN, Rouen, 76000, France
| | - Andrew N Clarkson
- Department of Anatomy, Brain Health Research Centre and Brain Research New Zealand, University of Otago, Dunedin, 76000, 9054, New Zealand
| | - Jérôme Leprince
- Normandie Université, UNIROUEN, Institut National de la Santé et de la Recherche Médicale U1239, Neuronal and Neuroendocrine Differentiation and Communication, Rouen, France
- Institute for Research and Innovation in Biomedicine, Normandie Université, PRIMACEN, Rouen, 76000, France
| | - Julien Chuquet
- Normandie Université, UNIROUEN, Institut National de la Santé et de la Recherche Médicale U1239, Neuronal and Neuroendocrine Differentiation and Communication, Rouen, France
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Extracellular Metalloproteinases in the Plasticity of Excitatory and Inhibitory Synapses. Cells 2021; 10:cells10082055. [PMID: 34440823 PMCID: PMC8391609 DOI: 10.3390/cells10082055] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 08/03/2021] [Accepted: 08/05/2021] [Indexed: 02/07/2023] Open
Abstract
Long-term synaptic plasticity is shaped by the controlled reorganization of the synaptic proteome. A key component of this process is local proteolysis performed by the family of extracellular matrix metalloproteinases (MMPs). In recent years, considerable progress was achieved in identifying extracellular proteases involved in neuroplasticity phenomena and their protein substrates. Perisynaptic metalloproteinases regulate plastic changes at synapses through the processing of extracellular and membrane proteins. MMP9 was found to play a crucial role in excitatory synapses by controlling the NMDA-dependent LTP component. In addition, MMP3 regulates the L-type calcium channel-dependent form of LTP as well as the plasticity of neuronal excitability. Both MMP9 and MMP3 were implicated in memory and learning. Moreover, altered expression or mutations of different MMPs are associated with learning deficits and psychiatric disorders, including schizophrenia, addiction, or stress response. Contrary to excitatory drive, the investigation into the role of extracellular proteolysis in inhibitory synapses is only just beginning. Herein, we review the principal mechanisms of MMP involvement in the plasticity of excitatory transmission and the recently discovered role of proteolysis in inhibitory synapses. We discuss how different matrix metalloproteinases shape dynamics and turnover of synaptic adhesome and signal transduction pathways in neurons. Finally, we discuss future challenges in exploring synapse- and plasticity-specific functions of different metalloproteinases.
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Rahmati N, Normoyle KP, Glykys J, Dzhala VI, Lillis KP, Kahle KT, Raiyyani R, Jacob T, Staley KJ. Unique Actions of GABA Arising from Cytoplasmic Chloride Microdomains. J Neurosci 2021; 41:4957-4975. [PMID: 33903223 PMCID: PMC8197632 DOI: 10.1523/jneurosci.3175-20.2021] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 03/10/2021] [Accepted: 04/10/2021] [Indexed: 12/21/2022] Open
Abstract
Developmental, cellular, and subcellular variations in the direction of neuronal Cl- currents elicited by GABAA receptor activation have been frequently reported. We found a corresponding variance in the GABAA receptor reversal potential (EGABA) for synapses originating from individual interneurons onto a single pyramidal cell. These findings suggest a similar heterogeneity in the cytoplasmic intracellular concentration of chloride ([Cl-]i) in individual dendrites. We determined [Cl-]i in the murine hippocampus and cerebral cortex of both sexes by (1) two-photon imaging of the Cl--sensitive, ratiometric fluorescent protein SuperClomeleon; (2) Fluorescence Lifetime IMaging (FLIM) of the Cl--sensitive fluorophore MEQ (6-methoxy-N-ethylquinolinium); and (3) electrophysiological measurements of EGABA by pressure application of GABA and RuBi-GABA uncaging. Fluorometric and electrophysiological estimates of local [Cl-]i were highly correlated. [Cl-]i microdomains persisted after pharmacological inhibition of cation-chloride cotransporters, but were progressively modified after inhibiting the polymerization of the anionic biopolymer actin. These methods collectively demonstrated stable [Cl-]i microdomains in individual neurons in vitro and in vivo and the role of immobile anions in its stability. Our results highlight the existence of functionally significant neuronal Cl- microdomains that modify the impact of GABAergic inputs.SIGNIFICANCE STATEMENT Microdomains of varying chloride concentrations in the neuronal cytoplasm are a predictable consequence of the inhomogeneous distribution of anionic polymers such as actin, tubulin, and nucleic acids. Here, we demonstrate the existence and stability of these microdomains, as well as the consequence for GABAergic synaptic signaling: each interneuron produces a postsynaptic GABAA response with a unique reversal potential. In individual hippocampal pyramidal cells, the range of GABAA reversal potentials evoked by stimulating different interneurons was >20 mV. Some interneurons generated postsynaptic responses in pyramidal cells that reversed at potentials beyond what would be considered purely inhibitory. Cytoplasmic chloride microdomains enable each pyramidal cell to maintain a compendium of unique postsynaptic responses to the activity of individual interneurons.
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Affiliation(s)
- Negah Rahmati
- Department of Neurology, Harvard Medical School and Massachusetts General Hospital, Boston, Massachusetts 02114
| | - Kieran P Normoyle
- Department of Neurology, Harvard Medical School and Massachusetts General Hospital, Boston, Massachusetts 02114
| | - Joseph Glykys
- Department of Pediatrics and Neurology, Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242
| | - Volodymyr I Dzhala
- Department of Neurology, Harvard Medical School and Massachusetts General Hospital, Boston, Massachusetts 02114
| | - Kyle P Lillis
- Department of Neurology, Harvard Medical School and Massachusetts General Hospital, Boston, Massachusetts 02114
| | - Kristopher T Kahle
- Departments of Neurosurgery, Pediatrics, and Cellular & Molecular Physiology, Yale School of Medicine, New Haven, Connecticut 06510
| | - Rehan Raiyyani
- Department of Neurology, Harvard Medical School and Massachusetts General Hospital, Boston, Massachusetts 02114
| | - Theju Jacob
- Department of Neurology, Harvard Medical School and Massachusetts General Hospital, Boston, Massachusetts 02114
| | - Kevin J Staley
- Department of Neurology, Harvard Medical School and Massachusetts General Hospital, Boston, Massachusetts 02114
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Parrini M, Naskar S, Alberti M, Colombi I, Morelli G, Rocchi A, Nanni M, Piccardi F, Charles S, Ronzitti G, Mingozzi F, Contestabile A, Cancedda L. Restoring neuronal chloride homeostasis with anti-NKCC1 gene therapy rescues cognitive deficits in a mouse model of Down syndrome. Mol Ther 2021; 29:3072-3092. [PMID: 34058387 PMCID: PMC8531145 DOI: 10.1016/j.ymthe.2021.05.023] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 04/27/2021] [Accepted: 05/18/2021] [Indexed: 01/24/2023] Open
Abstract
A common feature of diverse brain disorders is the alteration of GABA-mediated inhibition because of aberrant, intracellular chloride homeostasis induced by changes in the expression and/or function of chloride transporters. Notably, pharmacological inhibition of the chloride importer NKCC1 is able to rescue brain-related core deficits in animal models of these pathologies and in some human clinical studies. Here, we show that reducing NKCC1 expression by RNA interference in the Ts65Dn mouse model of Down syndrome (DS) restores intracellular chloride concentration, efficacy of gamma-aminobutyric acid (GABA)-mediated inhibition, and neuronal network dynamics in vitro and ex vivo. Importantly, adeno-associated virus (AAV)-mediated, neuron-specific NKCC1 knockdown in vivo rescues cognitive deficits in diverse behavioral tasks in Ts65Dn animals. Our results highlight a mechanistic link between NKCC1 expression and behavioral abnormalities in DS mice and establish a molecular target for new therapeutic approaches, including gene therapy, to treat brain disorders characterized by neuronal chloride imbalance.
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Affiliation(s)
- Martina Parrini
- Brain Development and Disease Laboratory, Istituto Italiano di Tecnologia, 16163 Genoa, Italy
| | - Shovan Naskar
- Brain Development and Disease Laboratory, Istituto Italiano di Tecnologia, 16163 Genoa, Italy
| | - Micol Alberti
- Brain Development and Disease Laboratory, Istituto Italiano di Tecnologia, 16163 Genoa, Italy
| | - Ilaria Colombi
- Brain Development and Disease Laboratory, Istituto Italiano di Tecnologia, 16163 Genoa, Italy
| | - Giovanni Morelli
- Brain Development and Disease Laboratory, Istituto Italiano di Tecnologia, 16163 Genoa, Italy
| | - Anna Rocchi
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, 16132 Genoa, Italy; IRCSS Ospedale Policlinico San Martino, 16132 Genoa, Italy
| | - Marina Nanni
- Brain Development and Disease Laboratory, Istituto Italiano di Tecnologia, 16163 Genoa, Italy
| | - Federica Piccardi
- Animal Facility, Istituto Italiano di Tecnologia, 16163 Genoa, Italy
| | - Severine Charles
- Genethon, 91000 Evry, France; Paris-Saclay University, University Evry, Inserm, Integrare research unit UMR_S951, 91000 Evry, France
| | - Giuseppe Ronzitti
- Genethon, 91000 Evry, France; Paris-Saclay University, University Evry, Inserm, Integrare research unit UMR_S951, 91000 Evry, France
| | - Federico Mingozzi
- Genethon, 91000 Evry, France; Paris-Saclay University, University Evry, Inserm, Integrare research unit UMR_S951, 91000 Evry, France
| | - Andrea Contestabile
- Brain Development and Disease Laboratory, Istituto Italiano di Tecnologia, 16163 Genoa, Italy.
| | - Laura Cancedda
- Brain Development and Disease Laboratory, Istituto Italiano di Tecnologia, 16163 Genoa, Italy; Dulbecco Telethon Institute, 00185 Rome, Italy.
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Intricacies of GABA A Receptor Function: The Critical Role of the β3 Subunit in Norm and Pathology. Int J Mol Sci 2021; 22:ijms22031457. [PMID: 33535681 PMCID: PMC7867123 DOI: 10.3390/ijms22031457] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 01/27/2021] [Accepted: 01/28/2021] [Indexed: 12/23/2022] Open
Abstract
Neuronal intracellular chloride ([Cl−]i) is a key determinant in γ-aminobutyric acid type A (GABA)ergic signaling. γ-Aminobutyric acid type A receptors (GABAARs) mediate both inhibitory and excitatory neurotransmission, as the passive fluxes of Cl− and HCO3− via pores can be reversed by changes in the transmembrane concentration gradient of Cl−. The cation–chloride co-transporters (CCCs) are the primary systems for maintaining [Cl−]i homeostasis. However, despite extensive electrophysiological data obtained in vitro that are supported by a wide range of molecular biological studies on the expression patterns and properties of CCCs, the presence of ontogenetic changes in [Cl−]i—along with the consequent shift in GABA reversal potential—remain a subject of debate. Recent studies showed that the β3 subunit possesses properties of the P-type ATPase that participates in the ATP-consuming movement of Cl− via the receptor. Moreover, row studies have demonstrated that the β3 subunit is a key player in GABAAR performance and in the appearance of serious neurological disorders. In this review, we discuss the properties and driving forces of CCCs and Cl−, HCO3−ATPase in the maintenance of [Cl−]i homeostasis after changes in upcoming GABAAR function. Moreover, we discuss the contribution of the β3 subunit in the manifestation of epilepsy, autism, and other syndromes.
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Wirth MJ, Ackels T, Kriebel A, Kriebel K, Mey J, Kuenzel T, Wagner H. Expression patterns of chloride transporters in the auditory brainstem of developing chicken. Hear Res 2020; 393:108013. [PMID: 32554128 DOI: 10.1016/j.heares.2020.108013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 04/29/2020] [Accepted: 05/29/2020] [Indexed: 01/23/2023]
Abstract
GABAergic transmission changes from depolarization to hyperpolarization in most vertebrate brain regions during development. By contrast, in the auditory brainstem of chicken a depolarizing effect of GABA persists after hatching. Since auditory brainstem neurons that receive GABAergic input have a Cl- reversal potential above resting membrane potential, a specifically tuned activity of Cl- transporters is likely. We here present a developmental study of the expression patterns of several members of the SLC12 family (NKCC1, NKCC2, KCC1, KCC2, KCC4, CCC6, CCC9) and of AE3 at developmental ages E7, E10, E12, E15, E17, and P1 with quantitative RT-PCR. NKCC2 and CCC9 were not detected in auditory brainstem (positive control: kidney). KCC1, CCC6 and AE3 were expressed, but not regulated, while NKCC1, KCC2 and KCC4 were regulated. The expression of the latter transporters increased, with KCC2 exhibiting the strongest expression at all time points. Biochemical analysis of the protein expression of NKCC1, KCC2 and KCC4 corroborated the findings on the mRNA level. All three transporters showed a localization at the outer rim of the cells, with NKCC1 and KCC2 expressed in neurons, and KCC4 predominantly in glia. The comparison of the published chloride reversal potential and expression of transporter proteins suggest strong differences in the efficiency of the three transporters. Further, the strong KCC2 expression could reflect a role in the structural development of auditory brainstem synapses that might lead to changes in the physiological properties.
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Affiliation(s)
- Marcus J Wirth
- Department for Chemosensation, RWTH Aachen University, Aachen, Germany.
| | - Tobias Ackels
- Neurophysiology of Behaviour Lab, The Francis Crick Institute, London, United Kingdom; Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Andreas Kriebel
- Department for Zoology and Animal Physiology, RWTH Aachen University, Aachen, Germany
| | - Katharina Kriebel
- Department for Zoology and Animal Physiology, RWTH Aachen University, Aachen, Germany
| | - Jörg Mey
- Department for Chemosensation, RWTH Aachen University, Aachen, Germany; Hospital Nacional de Parapléjicos, Toledo, Spain
| | - Thomas Kuenzel
- Department for Chemosensation, RWTH Aachen University, Aachen, Germany
| | - Hermann Wagner
- Department for Zoology and Animal Physiology, RWTH Aachen University, Aachen, Germany
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Bi D, Wen L, Wu Z, Shen Y. GABAergic dysfunction in excitatory and inhibitory (E/I) imbalance drives the pathogenesis of Alzheimer's disease. Alzheimers Dement 2020; 16:1312-1329. [PMID: 32543726 DOI: 10.1002/alz.12088] [Citation(s) in RCA: 91] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 01/28/2020] [Accepted: 02/10/2020] [Indexed: 12/28/2022]
Abstract
OBJECTIVE To propose a new hypothesis that GABAergic dysfunction in excitatory and inhibitory (E/I) imbalance drives the pathogenesis of Alzheimer's disease (AD). BACKGROUND Synaptic dysfunction and E/I imbalance emerge decades before the appearance of cognitive decline in AD patients, which contribute to neurodegeneration. Initially, E/I imbalance was thought to occur first, due to dysfunction of the glutamatergic and cholinergic systems. However, new evidence has demonstrated that the GABAergic system, the counterpart of E/I balance and the major inhibitory neurotransmitter system in the central nervous system, is altered enormously and that this contributes to E/I imbalance and further AD pathogenesis. NEW HYPOTHESIS Alterations to the GABAergic system, induced by multiple AD pathogenic or risk factors, contribute to E/I imbalance and AD pathogenesis. MAJOR CHALLENGES FOR THE HYPOTHESIS This GABAergic hypothesis accounts for many critical questions and common challenges confronting a new hypothesis of AD pathogenesis. More specifically, it explains why amyloid beta (Aβ), β-secretase (BACE1), apolipoprotein E4 gene (APOE ε4), hyperactive glia cells, contributes to AD pathogenesis and why age and sex are the risk factors of AD. GABAergic dysfunction promotes the spread of Aβ pathology throughout the AD brain and associated cognitive impairments, and the induction of dysfunction induced by these varied risk factors shares this common neurobiology leading to E/I imbalance. In turn, some of these factors exacerbate GABAergic dysfunction and E/I imbalance. Moreover, the GABAergic system modulates various brain functions and thus, the GABAergic hypothesis accounts for nonamnestic manifestations. Furthermore, corrections of E/I balance through manipulation of GABAergic functions have shown positive outcomes in preclinical and clinical studies, suggesting the potential of the GABAergic system as a therapeutic target in AD. LINKAGE TO OTHER MAJOR THEORIES Dysfunction of the GABAergic system is induced by multiple critical signaling pathways, which include the existing major theories of AD pathogenesis, such as the Aβ and neuroinflammation hypotheses. In a new perspective, this GABAergic hypothesis accounts for the E/I imbalance and related excitotoxicity, which contribute to cognitive decline and AD pathogenesis. Therefore, the GABAergic system could be a key target to restore, at least partially, the E/I balance and cognitive function in AD patients.
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Affiliation(s)
- Danlei Bi
- The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, Institute on Aging and Brain Disorders, University of Sciences and Technology of China, Hefei, China.,Neurodegenerative Disease Research Center, University of Science and Technology of China, Hefei, China.,Hefei National Laboratory for Physical Sciences at the Microscale, Neurodegenerative Disorder Research Center, CAS Key Laboratory of Brain Function and Disease, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Lang Wen
- The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, Institute on Aging and Brain Disorders, University of Sciences and Technology of China, Hefei, China.,Neurodegenerative Disease Research Center, University of Science and Technology of China, Hefei, China.,Hefei National Laboratory for Physical Sciences at the Microscale, Neurodegenerative Disorder Research Center, CAS Key Laboratory of Brain Function and Disease, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Zujun Wu
- The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, Institute on Aging and Brain Disorders, University of Sciences and Technology of China, Hefei, China.,Neurodegenerative Disease Research Center, University of Science and Technology of China, Hefei, China.,Hefei National Laboratory for Physical Sciences at the Microscale, Neurodegenerative Disorder Research Center, CAS Key Laboratory of Brain Function and Disease, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Yong Shen
- The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, Institute on Aging and Brain Disorders, University of Sciences and Technology of China, Hefei, China.,Neurodegenerative Disease Research Center, University of Science and Technology of China, Hefei, China.,Hefei National Laboratory for Physical Sciences at the Microscale, Neurodegenerative Disorder Research Center, CAS Key Laboratory of Brain Function and Disease, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
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29
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Bansal H, Gupta N, Roy S. Comparison of low-power, high-frequency and temporally precise optogenetic inhibition of spiking in NpHR, eNpHR3.0 and Jaws-expressing neurons. Biomed Phys Eng Express 2020; 6:045011. [PMID: 33444272 DOI: 10.1088/2057-1976/ab90a1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
A detailed theoretical analysis of low-power, high-frequency and temporally precise optogenetic inhibition of neuronal spiking, with red-shifted opsins namely, NpHR, eNpHR3.0 and Jaws, has been presented. An accurate model for inhibition of spiking in these opsins expressed hippocampal neurons that includes the important rebound activity of chloride ions across the membrane has been formulated. The effect of various parameters including irradiance, pulse width, frequency, opsin-expression density and chloride concentration has been studied in detail. Theoretical simulations are in very good agreement with reported experimental results. The chloride concentration gradient directly affects the photocurrent and inhibition capacity in all three variants. eNpHR3.0 shows smallest inhibitory post-synaptic potential plateau at higher frequencies. The time delay between light stimulus and target spike is crucial to minimize irradiance and expression density thresholds for suppressing individual spike. Good practical values of photostimulation parameters have been obtained empirically for peak photocurrent, time delay and 100% spiking inhibition, at continuous and pulsed illumination. Under continuous illumination, complete inhibition of neural activity in Jaws-expressing neurons takes place at minimum irradiance of 0.2 mW mm-2 and expression density of 0.2 mS cm-2, whereas for pulsed stimulation, it is at minimum irradiance of 0.6 mW mm-2 and 5 ms pulse width, at 10 Hz. It is shown that Jaws and eNpHR3.0 are able to invoke single spike precise inhibition up to 160 and 200 Hz, respectively. The study is useful in designing new experiments, understanding temporal spike coding and bidirectional control, and curing neurological disorders.
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Affiliation(s)
- Himanshu Bansal
- Department of Physics and Computer Science, Dayalbagh Educational Institute, Agra-282005, India
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30
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Currin CB, Trevelyan AJ, Akerman CJ, Raimondo JV. Chloride dynamics alter the input-output properties of neurons. PLoS Comput Biol 2020; 16:e1007932. [PMID: 32453795 PMCID: PMC7307785 DOI: 10.1371/journal.pcbi.1007932] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 06/22/2020] [Accepted: 05/06/2020] [Indexed: 12/30/2022] Open
Abstract
Fast synaptic inhibition is a critical determinant of neuronal output, with subcellular targeting of synaptic inhibition able to exert different transformations of the neuronal input-output function. At the receptor level, synaptic inhibition is primarily mediated by chloride-permeable Type A GABA receptors. Consequently, dynamics in the neuronal chloride concentration can alter the functional properties of inhibitory synapses. How differences in the spatial targeting of inhibitory synapses interact with intracellular chloride dynamics to modulate the input-output function of neurons is not well understood. To address this, we developed computational models of multi-compartment neurons that incorporate experimentally parametrised mechanisms to account for neuronal chloride influx, diffusion, and extrusion. We found that synaptic input (either excitatory, inhibitory, or both) can lead to subcellular variations in chloride concentration, despite a uniform distribution of chloride extrusion mechanisms. Accounting for chloride changes resulted in substantial alterations in the neuronal input-output function. This was particularly the case for peripherally targeted dendritic inhibition where dynamic chloride compromised the ability of inhibition to offset neuronal input-output curves. Our simulations revealed that progressive changes in chloride concentration mean that the neuronal input-output function is not static but varies significantly as a function of the duration of synaptic drive. Finally, we found that the observed effects of dynamic chloride on neuronal output were mediated by changes in the dendritic reversal potential for GABA. Our findings provide a framework for understanding the computational effects of chloride dynamics on dendritically targeted synaptic inhibition.
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Affiliation(s)
- Christopher B. Currin
- Division of Cell Biology, Department of Human Biology, Neuroscience Institute and Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Andrew J. Trevelyan
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Colin J. Akerman
- Department of Pharmacology, University of Oxford, Oxford, United Kingdom
| | - Joseph V. Raimondo
- Division of Cell Biology, Department of Human Biology, Neuroscience Institute and Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
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Isoflurane Modulates Hippocampal Cornu Ammonis Pyramidal Neuron Excitability by Inhibition of Both Transient and Persistent Sodium Currents in Mice. Anesthesiology 2020; 131:94-104. [PMID: 31166240 DOI: 10.1097/aln.0000000000002753] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND Volatile anesthetics inhibit presynaptic voltage-gated sodium channels to reduce neurotransmitter release, but their effects on excitatory neuron excitability by sodium current inhibition are unclear. The authors hypothesized that inhibition of transient and persistent neuronal sodium currents by the volatile anesthetic isoflurane contributes to reduced hippocampal pyramidal neuron excitability. METHODS Whole-cell patch-clamp recordings of sodium currents of hippocampal cornu ammonis pyramidal neurons were performed in acute mouse brain slices. The actions of isoflurane on both transient and persistent sodium currents were analyzed at clinically relevant concentrations of isoflurane. RESULTS The median inhibitory concentration of isoflurane for inhibition of transient sodium currents was 1.0 ± 0.3 mM (~3.7 minimum alveolar concentration [MAC]) from a physiologic holding potential of -70 mV. Currents from a hyperpolarized holding potential of -120 mV were minimally inhibited (median inhibitory concentration = 3.6 ± 0.7 mM, ~13.3 MAC). Isoflurane (0.55 mM; ~2 MAC) shifted the voltage-dependence of steady-state inactivation by -6.5 ± 1.0 mV (n = 11, P < 0.0001), but did not affect the voltage-dependence of activation. Isoflurane increased the time constant for sodium channel recovery from 7.5 ± 0.6 to 12.7 ± 1.3 ms (n = 13, P < 0.001). Isoflurane also reduced persistent sodium current density (median inhibitory concentration = 0.4 ± 0.1 mM, ~1.5 MAC) and resurgent currents. Isoflurane (0.55 mM; ~2 MAC) reduced action potential amplitude, and hyperpolarized resting membrane potential from -54.6 ± 2.3 to -58.7 ± 2.1 mV (n = 16, P = 0.001). CONCLUSIONS Isoflurane at clinically relevant concentrations inhibits both transient and persistent sodium currents in hippocampal cornu ammonis pyramidal neurons. These mechanisms may contribute to reductions in both hippocampal neuron excitability and synaptic neurotransmission.
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Auer T, Schreppel P, Erker T, Schwarzer C. Impaired chloride homeostasis in epilepsy: Molecular basis, impact on treatment, and current treatment approaches. Pharmacol Ther 2020; 205:107422. [DOI: 10.1016/j.pharmthera.2019.107422] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Accepted: 10/07/2019] [Indexed: 12/14/2022]
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Brain microstructural abnormalities correlate with KCC2 downregulation in refractory epilepsy. Neuroreport 2019; 30:409-414. [PMID: 30817684 DOI: 10.1097/wnr.0000000000001216] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Dysregulations in the expression level of Na-K-Cl cotransporter (NKCC1) and K-Cl cotransporter (KCC2) genes have been detected in the brain tissues of patients with refractory epilepsy. Given the importance of these proteins in the determination of Cl equilibrium potential (ECl), evaluation of the expression changes of these transporters might assist in optimizing the diagnostic approaches and therapeutic strategies. The present investigation evaluates the expression level chloride transporters in polymorphonuclear cells and their correlation with microstructural abnormalities. Thirty cases of drug-resistant epilepsy (confirmed with temporal lobe epilepsy diagnosis) fulfilled the considered inclusion criteria. Cases were divided into two groups, one with a detectable MRI lesion (19 participants; right side) and another with no MRI findings (11 participants). Whole-brain voxel-based analysis was performed on diffusion tensor imaging to measure fractional anisotropy and mean diffusivity; neurite orientation dispersion and density imaging was performed to map neurite density index and orientation dispersion index. Our results indicated that fractional anisotropy and mean diffusivity changed in temporal and extratemporal parts of the brain, whereas the changes in neurite density index and orientation dispersion index were exclusively obvious in the temporal lobe. Molecular studies revealed significantly lower levels of KCC2 expression in patients with epilepsy, a finding that remarkably correlated with microstructural changes as well. Our research showed that downregulation of KCC2 and microstructural abnormalities might contribute to the observed refractoriness in temporal lobe epilepsy.
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Kardos J, Dobolyi Á, Szabó Z, Simon Á, Lourmet G, Palkovits M, Héja L. Molecular Plasticity of the Nucleus Accumbens Revisited-Astrocytic Waves Shall Rise. Mol Neurobiol 2019; 56:7950-7965. [PMID: 31134458 PMCID: PMC6834761 DOI: 10.1007/s12035-019-1641-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Accepted: 05/06/2019] [Indexed: 12/11/2022]
Abstract
Part of the ventral striatal division, the nucleus accumbens (NAc) drives the circuit activity of an entire macrosystem about reward like a "flagship," signaling and leading diverse conducts. Accordingly, NAc neurons feature complex inhibitory phenotypes that assemble to process circuit inputs and generate outputs by exploiting specific arrays of opposite and/or parallel neurotransmitters, neuromodulatory peptides. The resulting complex combinations enable versatile yet specific forms of accumbal circuit plasticity, including maladaptive behaviors. Although reward signaling and behavior are elaborately linked to neuronal circuit activities, it is plausible to propose whether these neuronal ensembles and synaptic islands can be directly controlled by astrocytes, a powerful modulator of neuronal activity. Pioneering studies showed that astrocytes in the NAc sense citrate cycle metabolites and/or ATP and may induce recurrent activation. We argue that the astrocytic calcium, GABA, and Glu signaling and altered sodium and chloride dynamics fundamentally shape metaplasticity by providing active regulatory roles in the synapse- and network-level flexibility of the NAc.
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Affiliation(s)
- Julianna Kardos
- Functional Pharmacology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok körútja 2, Budapest, 1117, Hungary.
| | - Árpád Dobolyi
- Laboratory of Neuromorphology, Department of Anatomy, Histology and Embryology, Semmelweis University, Üllői út 26, Budapest, 1086, Hungary
- MTA-ELTE Laboratory of Molecular and Systems Neurobiology, Department of Physiology and Neurobiology, Eötvös Loránd University and the Hungarian Academy of Sciences, Pázmány Péter sétány 1C, Budapest, 1117, Hungary
| | - Zsolt Szabó
- Functional Pharmacology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok körútja 2, Budapest, 1117, Hungary
| | - Ágnes Simon
- Functional Pharmacology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok körútja 2, Budapest, 1117, Hungary
| | - Guillaume Lourmet
- Laboratory of Neuromorphology, Department of Anatomy, Histology and Embryology, Semmelweis University, Üllői út 26, Budapest, 1086, Hungary
| | - Miklós Palkovits
- Human Brain Tissue Bank, Semmelweis University, Tűzoltó utca 58, Budapest, H-1094, Hungary
| | - László Héja
- Functional Pharmacology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok körútja 2, Budapest, 1117, Hungary
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35
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The Widespread Network Effects of Focal Epilepsy. J Neurosci 2019; 38:8107-8109. [PMID: 30232147 DOI: 10.1523/jneurosci.1471-18.2018] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 07/31/2018] [Accepted: 08/02/2018] [Indexed: 01/20/2023] Open
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36
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Ménard C, Folacci M, Brunello L, Charreton M, Collet C, Mary R, Rousset M, Thibaud JB, Vignes M, Charnet P, Cens T. Multiple combinations of RDL subunits diversify the repertoire of GABA receptors in the honey bee parasite Varroa destructor. J Biol Chem 2018; 293:19012-19024. [PMID: 30333227 DOI: 10.1074/jbc.ra118.005365] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 10/16/2018] [Indexed: 12/22/2022] Open
Abstract
In insects, γ-aminobutyric acid (GABA) is the major inhibitory neurotransmitter, and GABA-gated ion channels are the target of different classes of insecticides, including fipronil. We report here the cloning of six subunits (four RDL, one LCCH3, and one GRD) that constitute the repertoire of the GABA-gated ion channel family of the Varroa mite (Varroa destructor), a honey bee ectoparasite. We also isolated a truncated GRD subunit with a premature stop codon. We found that when expressed in Xenopus laevis oocytes, three of the four RDL subunits (VdesRDL1, VdesRDL2, and VdesRDL3) formed functional, homomultimeric anionic receptors, whereas GRD and LCCH3 produced heteromultimeric cationic receptors. These receptors displayed specific sensitivities toward GABA and fipronil, and VdesRDL1 was the most resistant to the insecticide. We identified specific residues in the VdesRDL1 pore-lining region that explain its high resistance to fipronil. VdesRDL4 did not form a functional receptor when expressed alone, but it assembled with VdesRDL1 to form a heteromultimeric receptor with properties distinct from those of the VdesRDL1 homomultimeric receptor. Moreover, VdesRDL1 physically interacted with VdesRDL3, generating a heteromultimeric receptor combining properties of both subunits. On the other hand, we did not detect any functional interaction between VdesLCCH3 and the VdesRDL subunits, an observation that differed from what was previously reported for Drosophila melanogaster In conclusion, this study provides insights relevant to improve our understanding of the precise role of GABAergic signaling in insects and new tools for the development of Varroa mite-specific insecticidal agents that do not harm honey bees.
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Affiliation(s)
- Claudine Ménard
- From the Institut des Biomolécules Max Mousseron, UMR5247, CNRS, Université de Montpellier, 34095 Montpellier cedex 5, France and
| | - Mathilde Folacci
- From the Institut des Biomolécules Max Mousseron, UMR5247, CNRS, Université de Montpellier, 34095 Montpellier cedex 5, France and
| | - Lorène Brunello
- From the Institut des Biomolécules Max Mousseron, UMR5247, CNRS, Université de Montpellier, 34095 Montpellier cedex 5, France and
| | - Mercedes Charreton
- the INRA UR 406 Abeilles et Environnement, 84914 Avignon cedex 9, France
| | - Claude Collet
- the INRA UR 406 Abeilles et Environnement, 84914 Avignon cedex 9, France
| | - Rosanna Mary
- From the Institut des Biomolécules Max Mousseron, UMR5247, CNRS, Université de Montpellier, 34095 Montpellier cedex 5, France and
| | - Matthieu Rousset
- From the Institut des Biomolécules Max Mousseron, UMR5247, CNRS, Université de Montpellier, 34095 Montpellier cedex 5, France and
| | - Jean-Baptiste Thibaud
- From the Institut des Biomolécules Max Mousseron, UMR5247, CNRS, Université de Montpellier, 34095 Montpellier cedex 5, France and
| | - Michel Vignes
- From the Institut des Biomolécules Max Mousseron, UMR5247, CNRS, Université de Montpellier, 34095 Montpellier cedex 5, France and
| | - Pierre Charnet
- From the Institut des Biomolécules Max Mousseron, UMR5247, CNRS, Université de Montpellier, 34095 Montpellier cedex 5, France and
| | - Thierry Cens
- From the Institut des Biomolécules Max Mousseron, UMR5247, CNRS, Université de Montpellier, 34095 Montpellier cedex 5, France and
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Düsterwald KM, Currin CB, Burman RJ, Akerman CJ, Kay AR, Raimondo JV. Biophysical models reveal the relative importance of transporter proteins and impermeant anions in chloride homeostasis. eLife 2018; 7:39575. [PMID: 30260315 PMCID: PMC6200395 DOI: 10.7554/elife.39575] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 09/24/2018] [Indexed: 11/17/2022] Open
Abstract
Fast synaptic inhibition in the nervous system depends on the transmembrane flux of Cl- ions based on the neuronal Cl- driving force. Established theories regarding the determinants of Cl- driving force have recently been questioned. Here, we present biophysical models of Cl- homeostasis using the pump-leak model. Using numerical and novel analytic solutions, we demonstrate that the Na+/K+-ATPase, ion conductances, impermeant anions, electrodiffusion, water fluxes and cation-chloride cotransporters (CCCs) play roles in setting the Cl- driving force. Our models, together with experimental validation, show that while impermeant anions can contribute to setting [Cl-]i in neurons, they have a negligible effect on the driving force for Cl- locally and cell-wide. In contrast, we demonstrate that CCCs are well-suited for modulating Cl- driving force and hence inhibitory signaling in neurons. Our findings reconcile recent experimental findings and provide a framework for understanding the interplay of different chloride regulatory processes in neurons. Cells called neurons in the brain communicate by triggering or inhibiting electrical activity in other neurons. To inhibit electrical activity, a signal from one neuron usually triggers specific receptors on the second neuron to open, which allows particles called chloride ions to flow into or out of the neuron. The force that moves chloride ions (the so-called ‘chloride driving force’) depends on two main factors. Firstly, chloride ions, like other particles, tend to move from an area where they are plentiful to areas where they are less abundant. Secondly, chloride ions are negatively charged and are therefore attracted to areas where the net charge (determined by the mix of positively and negatively charged particles) is more positive than their current position. It was previously believed that a group of proteins known as CCCs, which transport chloride ions and positive ions together across the membranes surrounding cells, sets the chloride driving force. However, it has recently been suggested that negatively charged ions that are unable to cross the membrane (or ‘impermeant anions’ for short) may set the driving force instead by contributing to the net charge across the membrane. Düsterwald et al. used a computational model of the neuron to explore these two possibilities. In the simulations, altering the activity of the CCCs led to big changes in the chloride driving force. Changing the levels of impermeant anions altered the volume of cells, but did not drive changes in the chloride driving force. This was because the flow of chloride ions across the membrane led to a compensatory change in the net charge across the membrane. Düsterwald et al. then used an experimental technique called patch-clamping in mice and rats to confirm the model’s predictions. Defects in controlling the chloride driving force in brain cells have been linked with epilepsy, stroke and other neurological diseases. Therefore, a better knowledge of these mechanisms may in future help to identify the best targets for drugs to treat such conditions.
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Affiliation(s)
- Kira M Düsterwald
- Division of Cell Biology, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.,Neuroscience Institute, University of Cape Town, Cape Town, South Africa.,Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Cape Town, South Africa
| | - Christopher B Currin
- Division of Cell Biology, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.,Neuroscience Institute, University of Cape Town, Cape Town, South Africa.,Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Cape Town, South Africa
| | - Richard J Burman
- Division of Cell Biology, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.,Neuroscience Institute, University of Cape Town, Cape Town, South Africa.,Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Cape Town, South Africa
| | - Colin J Akerman
- Department of Pharmacology, University of Oxford, Oxford, United Kingdom
| | - Alan R Kay
- Department of Biology, University of Iowa, Iowa City Iowa, United States
| | - Joseph V Raimondo
- Division of Cell Biology, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.,Neuroscience Institute, University of Cape Town, Cape Town, South Africa.,Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Cape Town, South Africa
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Roux S, Lohof A, Ben-Ari Y, Poulain B, Bossu JL. Maturation of GABAergic Transmission in Cerebellar Purkinje Cells Is Sex Dependent and Altered in the Valproate Model of Autism. Front Cell Neurosci 2018; 12:232. [PMID: 30104962 PMCID: PMC6077203 DOI: 10.3389/fncel.2018.00232] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 07/16/2018] [Indexed: 12/20/2022] Open
Abstract
Brain development is accompanied by a shift in gamma-aminobutyric acid (GABA) response from depolarizing-excitatory to hyperpolarizing-inhibitory, due to a reduction of intracellular chloride concentration. This sequence is delayed in Autism Spectrum Disorders (ASD). We now report a similar alteration of this shift in the cerebellum, a structure implicated in ASD. Using single GABAA receptor channel recordings in cerebellar Purkinje cells (PCs), we found two conductance levels (18 and 10 pS), the former being dominant in newborns and the latter in young-adults. This conductance shift and the depolarizing/excitatory to hyperpolarizing/inhibitory GABA shift occurred 4 days later in females than males. Our data support a sex-dependent developmental shift of GABA conductance and chloride gradient, leading to different developmental timing in males and females. Because these developmental sequences are altered in ASD, this study further stresses the importance of developmental timing in pathological neurodevelopment.
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Affiliation(s)
- Sébastien Roux
- Institut des Neurosciences Cellulaires et Intégratives (INCI)-CNRS, UPR 3212, Strasbourg, France
| | - Ann Lohof
- Sorbonne Université, CNRS UMR 8256, Biological Adaptation and Ageing, Paris, France
| | - Yehezkel Ben-Ari
- Neurochlore, Ben-Ari Institute of Neuroarcheology, Campus Scientifique de Luminy, Aix Marseille Université, Marseille, France
| | - Bernard Poulain
- Institut des Neurosciences Cellulaires et Intégratives (INCI)-CNRS, UPR 3212, Strasbourg, France
| | - Jean-Louis Bossu
- Institut des Neurosciences Cellulaires et Intégratives (INCI)-CNRS, UPR 3212, Strasbourg, France
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Schulte JT, Wierenga CJ, Bruining H. Chloride transporters and GABA polarity in developmental, neurological and psychiatric conditions. Neurosci Biobehav Rev 2018; 90:260-271. [PMID: 29729285 DOI: 10.1016/j.neubiorev.2018.05.001] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 03/20/2018] [Accepted: 05/01/2018] [Indexed: 12/22/2022]
Abstract
Neuronal chloride regulation is a determinant factor for the dynamic tuning of GABAergic inhibition during and beyond brain development. This regulation is mainly dependent on the two co-transporters K+/Cl- co-transporter KCC2 and Na+/K+/Cl- co-transporter NKCC1, whose activity can decrease or increase neuronal chloride concentrations respectively. Altered expression and/or activity of either of these co-transporters has been associated with a wide variety of brain disorders including developmental disorders, epilepsy, schizophrenia and stroke. Here, we review current knowledge on chloride transporter expression and activity regulation and highlight the intriguing potential for existing and future interventions to support chloride homeostasis across a wide range of mental disorders and neurological conditions.
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Affiliation(s)
- Joran T Schulte
- Department of Psychiatry, Brain Center Rudolf Magnus, University Medical Center, Heidelberglaan 100, 3508 GA Utrecht The Netherlands
| | - Corette J Wierenga
- Division of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
| | - Hilgo Bruining
- Department of Psychiatry, Brain Center Rudolf Magnus, University Medical Center, Heidelberglaan 100, 3508 GA Utrecht The Netherlands.
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40
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Pozzi D, Menna E, Canzi A, Desiato G, Mantovani C, Matteoli M. The Communication Between the Immune and Nervous Systems: The Role of IL-1β in Synaptopathies. Front Mol Neurosci 2018; 11:111. [PMID: 29674955 PMCID: PMC5895746 DOI: 10.3389/fnmol.2018.00111] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2018] [Accepted: 03/20/2018] [Indexed: 12/14/2022] Open
Abstract
In the last 15 years, groundbreaking genetic progress has underlined a convergence onto coherent synaptic pathways for most psychiatric and neurodevelopmental disorders, which are now collectively called “synaptopathies.” However, the modest size of inheritance detected so far indicates a multifactorial etiology for these disorders, underlining the key contribution of environmental effects to them. Inflammation is known to influence the risk and/or severity of a variety of synaptopathies. In particular, pro-inflammatory cytokines, produced and released in the brain by activated astrocytes and microglia, may play a pivotal role in these pathologies. Although the link between immune system activation and defects in cognitive processes is nowadays clearly established, the knowledge of the molecular mechanisms by which inflammatory mediators specifically hit synaptic components implicated in synaptopathies is still in its infancy. This review summarizes recent evidence showing that the pro-inflammatory cytokine interleukin-1β (IL-1β) specifically targets synaptopathy molecular substrate, leading to memory defects and pathological processes. In particular, we describe three specific pathways through which IL-1β affects (1) synaptic maintenance/dendritic complexity, (2) spine morphology, and (3) the excitatory/inhibitory balance. We coin the term immune synaptopathies to identify this class of diseases.
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Affiliation(s)
- Davide Pozzi
- Department of Biomedical Sciences, Humanitas University, Rozzano, Italy.,Humanitas Clinical and Research Center, Rozzano, Italy
| | - Elisabetta Menna
- Humanitas Clinical and Research Center, Rozzano, Italy.,Istituto di Neuroscienze, Consiglio Nazionale delle Ricerche, Milan, Italy
| | - Alice Canzi
- Department of Biomedical Sciences, Humanitas University, Rozzano, Italy
| | - Genni Desiato
- Humanitas Clinical and Research Center, Rozzano, Italy.,School of Medicine and Surgery, University of Milan-Bicocca, Milan, Italy
| | | | - Michela Matteoli
- Humanitas Clinical and Research Center, Rozzano, Italy.,Istituto di Neuroscienze, Consiglio Nazionale delle Ricerche, Milan, Italy
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Developmental excitatory-to-inhibitory GABA-polarity switch is disrupted in 22q11.2 deletion syndrome: a potential target for clinical therapeutics. Sci Rep 2017; 7:15752. [PMID: 29146941 PMCID: PMC5691208 DOI: 10.1038/s41598-017-15793-9] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Accepted: 11/01/2017] [Indexed: 12/22/2022] Open
Abstract
Individuals with 22q11.2 microdeletion syndrome (22q11.2 DS) show cognitive and behavioral dysfunctions, developmental delays in childhood and risk of developing schizophrenia and autism. Despite extensive previous studies in adult animal models, a possible embryonic root of this syndrome has not been determined. Here, in neurons from a 22q11.2 DS mouse model (Lgdel+/−), we found embryonic-premature alterations in the neuronal chloride cotransporters indicated by dysregulated NKCC1 and KCC2 protein expression levels. We demonstrate with large-scale spiking activity recordings a concurrent deregulation of the spontaneous network activity and homeostatic network plasticity. Additionally, Lgdel+/− networks at early development show abnormal neuritogenesis and void of synchronized spontaneous activity. Furthermore, parallel experiments on Dgcr8+/− mouse cultures reveal a significant, yet not exclusive contribution of the dgcr8 gene to our phenotypes of Lgdel+/− networks. Finally, we show that application of bumetanide, an inhibitor of NKCC1, significantly decreases the hyper-excitable action of GABAA receptor signaling and restores network homeostatic plasticity in Lgdel+/− networks. Overall, by exploiting an on-a-chip 22q11.2 DS model, our results suggest a delayed GABA-switch in Lgdel+/− neurons, which may contribute to a delayed embryonic development. Prospectively, acting on the GABA-polarity switch offers a potential target for 22q11.2 DS therapeutic intervention.
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Shimizu K, Stopfer M. A Population of Projection Neurons that Inhibits the Lateral Horn but Excites the Antennal Lobe through Chemical Synapses in Drosophila. Front Neural Circuits 2017; 11:30. [PMID: 28515683 PMCID: PMC5413558 DOI: 10.3389/fncir.2017.00030] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Accepted: 04/10/2017] [Indexed: 11/15/2022] Open
Abstract
In the insect olfactory system, odor information is transferred from the antennal lobe (AL) to higher brain areas by projection neurons (PNs) in multiple AL tracts (ALTs). In several species, one of the ALTs, the mediolateral ALT (mlALT), contains some GABAergic PNs; in the Drosophila brain, the great majority of ventral PNs (vPNs) are GABAergic and project through this tract to the lateral horn (LH). Most excitatory PNs (ePNs), project through the medial ALT (mALT) to the mushroom body (MB) and the LH. Recent studies have shown that GABAergic vPNs play inhibitory roles at their axon terminals in the LH. However, little is known about the properties and functions of vPNs at their dendritic branches in the AL. Here, we used optogenetic and patch clamp techniques to investigate the functional roles of vPNs in the AL. Surprisingly, our results show that specific activation of vPNs reliably elicits strong excitatory postsynaptic potentials (EPSPs) in ePNs. Moreover, the connections between vPNs and ePNs are mediated by direct chemical synapses. Neither pulses of GABA, nor pharmagological, or genetic blockade of GABAergic transmission gave results consistent with the involvement of GABA in vPN-ePN excitatory transmission. These unexpected results suggest new roles for the vPN population in olfactory information processing.
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Affiliation(s)
- Kazumichi Shimizu
- National Institute of Child Health and Human Development, National Institutes of HealthBethesda, MD, USA
| | - Mark Stopfer
- National Institute of Child Health and Human Development, National Institutes of HealthBethesda, MD, USA
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Berlin S, Isacoff EY. Synapses in the spotlight with synthetic optogenetics. EMBO Rep 2017; 18:677-692. [PMID: 28396573 DOI: 10.15252/embr.201744010] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 03/02/2017] [Accepted: 03/09/2017] [Indexed: 12/15/2022] Open
Abstract
Membrane receptors and ion channels respond to various stimuli and relay that information across the plasma membrane by triggering specific and timed processes. These include activation of second messengers, allowing ion permeation, and changing cellular excitability, to name a few. Gaining control over equivalent processes is essential to understand neuronal physiology and pathophysiology. Recently, new optical techniques have emerged proffering new remote means to control various functions of defined neuronal populations by light, dubbed optogenetics. Still, optogenetic tools do not typically address the activity of receptors and channels native to neurons (or of neuronal origin), nor gain access to their signaling mechanisms. A related method-synthetic optogenetics-bridges this gap by endowing light sensitivity to endogenous neuronal receptors and channels by the appending of synthetic, light-receptive molecules, or photoswitches. This provides the means to photoregulate neuronal receptors and channels and tap into their native signaling mechanisms in select regions of the neurons, such as the synapse. This review discusses the development of synthetic optogenetics as a means to study neuronal receptors and channels remotely, in their natural environment, with unprecedented spatial and temporal precision, and provides an overview of tool design, mode of action, potential clinical applications and insights and achievements gained.
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Affiliation(s)
- Shai Berlin
- The Ruth and Bruce Rappaport Faculty of Medicine, Technion- Israel Institute of Technology, Haifa, Israel
| | - Ehud Y Isacoff
- Helen Wills Neuroscience Institute, University of California, Berkeley, CA, USA.,Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA.,Physical Bioscience Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
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