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Topchiy I, Mohbat J, Folorunso OO, Wang ZZ, Lazcano-Etchebarne C, Engin E. GABA system as the cause and effect in early development. Neurosci Biobehav Rev 2024; 161:105651. [PMID: 38579901 PMCID: PMC11081854 DOI: 10.1016/j.neubiorev.2024.105651] [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: 01/03/2024] [Revised: 03/05/2024] [Accepted: 04/01/2024] [Indexed: 04/07/2024]
Abstract
GABA is the primary inhibitory neurotransmitter in the adult brain and through its actions on GABAARs, it protects against excitotoxicity and seizure activity, ensures temporal fidelity of neurotransmission, and regulates concerted rhythmic activity of neuronal populations. In the developing brain, the development of GABAergic neurons precedes that of glutamatergic neurons and the GABA system serves as a guide and framework for the development of other brain systems. Despite this early start, the maturation of the GABA system also continues well into the early postnatal period. In this review, we organize evidence around two scenarios based on the essential and protracted nature of GABA system development: 1) disruptions in the development of the GABA system can lead to large scale disruptions in other developmental processes (i.e., GABA as the cause), 2) protracted maturation of this system makes it vulnerable to the effects of developmental insults (i.e., GABA as the effect). While ample evidence supports the importance of GABA/GABAAR system in both scenarios, large gaps in existing knowledge prevent strong mechanistic conclusions.
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Affiliation(s)
- Irina Topchiy
- Division of Basic Neuroscience, McLean Hospital, Belmont, MA 02478, USA; Department of Psychiatry, Harvard Medical School, Boston, MA 02215, USA
| | - Julie Mohbat
- Division of Basic Neuroscience, McLean Hospital, Belmont, MA 02478, USA; Department of Psychiatry, Harvard Medical School, Boston, MA 02215, USA; School of Life Sciences, Ecole Polytechnique Federale de Lausanne, Lausanne CH-1015, Switzerland
| | - Oluwarotimi O Folorunso
- Division of Basic Neuroscience, McLean Hospital, Belmont, MA 02478, USA; Department of Psychiatry, Harvard Medical School, Boston, MA 02215, USA
| | - Ziyi Zephyr Wang
- Division of Basic Neuroscience, McLean Hospital, Belmont, MA 02478, USA; Department of Psychiatry, Harvard Medical School, Boston, MA 02215, USA
| | | | - Elif Engin
- Division of Basic Neuroscience, McLean Hospital, Belmont, MA 02478, USA; Department of Psychiatry, Harvard Medical School, Boston, MA 02215, USA.
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2
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Kim JJ, Hibbs RE. Direct Structural Insights into GABA A Receptor Pharmacology. Trends Biochem Sci 2021; 46:502-517. [PMID: 33674151 DOI: 10.1016/j.tibs.2021.01.011] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 01/08/2021] [Accepted: 01/25/2021] [Indexed: 12/18/2022]
Abstract
GABAA receptors are pentameric ligand-gated ion channels that mediate most fast neuronal inhibition in the brain. In addition to their important physiological roles, they are noteworthy in their rich pharmacology; prominent drugs used for anxiety, insomnia, and general anesthesia act through positive modulation of GABAA receptors. Direct structural information for how these drugs work was absent until recently. Efforts in structural biology over the past few years have revealed how important drug classes and natural products interact with the GABAA receptor, providing a foundation for studies in dynamics and structure-guided drug design. Here, we review recent developments in GABAA receptor structural pharmacology, focusing on subunit assemblies of the receptor found at synapses.
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Affiliation(s)
- Jeong Joo Kim
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Ryan E Hibbs
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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3
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Kim JJ, Gharpure A, Teng J, Zhuang Y, Howard RJ, Zhu S, Noviello CM, Walsh RM, Lindahl E, Hibbs RE. Shared structural mechanisms of general anaesthetics and benzodiazepines. Nature 2020; 585:303-308. [PMID: 32879488 PMCID: PMC7486282 DOI: 10.1038/s41586-020-2654-5] [Citation(s) in RCA: 171] [Impact Index Per Article: 42.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 06/01/2020] [Indexed: 01/17/2023]
Abstract
Most general anaesthetics and classical benzodiazepine drugs act through positive modulation of γ-aminobutyric acid type A (GABAA) receptors to dampen neuronal activity in the brain1-5. However, direct structural information on the mechanisms of general anaesthetics at their physiological receptor sites is lacking. Here we present cryo-electron microscopy structures of GABAA receptors bound to intravenous anaesthetics, benzodiazepines and inhibitory modulators. These structures were solved in a lipidic environment and are complemented by electrophysiology and molecular dynamics simulations. Structures of GABAA receptors in complex with the anaesthetics phenobarbital, etomidate and propofol reveal both distinct and common transmembrane binding sites, which are shared in part by the benzodiazepine drug diazepam. Structures in which GABAA receptors are bound by benzodiazepine-site ligands identify an additional membrane binding site for diazepam and suggest an allosteric mechanism for anaesthetic reversal by flumazenil. This study provides a foundation for understanding how pharmacologically diverse and clinically essential drugs act through overlapping and distinct mechanisms to potentiate inhibitory signalling in the brain.
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Affiliation(s)
- Jeong Joo Kim
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Anant Gharpure
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Jinfeng Teng
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Yuxuan Zhuang
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, Solna, Sweden
| | - Rebecca J Howard
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, Solna, Sweden
| | - Shaotong Zhu
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Colleen M Noviello
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Richard M Walsh
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Erik Lindahl
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, Solna, Sweden
- Department of Applied Physics, Swedish e-Science Research Center, KTH Royal Institute of Technology, Solna, Sweden
| | - Ryan E Hibbs
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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4
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Kreuzer M, Butovas S, García PS, Schneider G, Schwarz C, Rudolph U, Antkowiak B, Drexler B. Propofol Affects Cortico-Hippocampal Interactions via β3 Subunit-Containing GABA A Receptors. Int J Mol Sci 2020; 21:ijms21165844. [PMID: 32823959 PMCID: PMC7461501 DOI: 10.3390/ijms21165844] [Citation(s) in RCA: 4] [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: 07/22/2020] [Revised: 08/05/2020] [Accepted: 08/07/2020] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND General anesthetics depress neuronal activity. The depression and uncoupling of cortico-hippocampal activity may contribute to anesthetic-induced amnesia. However, the molecular targets involved in this process are not fully characterized. GABAA receptors, especially the type with β3 subunits, represent a main molecular target of propofol. We therefore hypothesized that GABAA receptors with β3 subunits mediate the propofol-induced disturbance of cortico-hippocampal interactions. METHODS We used local field potential (LFP) recordings from chronically implanted cortical and hippocampal electrodes in wild-type and β3(N265M) knock-in mice. In the β3(N265M) mice, the action of propofol via β3subunit containing GABAA receptors is strongly attenuated. The analytical approach contained spectral power, phase locking, and mutual information analyses in the 2-16 Hz range to investigate propofol-induced effects on cortico-hippocampal interactions. RESULTS Propofol caused a significant increase in spectral power between 14 and 16 Hz in the cortex and hippocampus of wild-type mice. This increase was absent in the β3(N265M) mutant. Propofol strongly decreased phase locking of 6-12 Hz oscillations in wild-type mice. This decrease was attenuated in the β3(N265M) mutant. Finally, propofol reduced the mutual information between 6-16 Hz in wild-type mice, but only between 6 and 8 Hz in the β3(N265M) mutant. CONCLUSIONS GABAA receptors containing β3 subunits contribute to frequency-specific perturbation of cortico-hippocampal interactions. This likely explains some of the amnestic actions of propofol.
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Affiliation(s)
- Matthias Kreuzer
- Department of Anesthesiology and Intensive Care, Klinikum rechts der Isar, Technical University of Munich, School of Medicine, Munich, Ismaninger Str. 22, 81675 München, Germany; (M.K.); (G.S.)
| | - Sergejus Butovas
- Werner Reichardt Centre for Integrative Neuroscience, Eberhard-Karls-University, Otfried-Müller-Str. 25, 72076 Tübingen, Germany; (S.B.); (C.S.)
| | - Paul S García
- Department of Anesthesiology, Neuroanesthesia Division, Columbia University Medical Center, New York Presbyterian Hospital, 622 West 168th Street, New York City, NY 10032, USA;
| | - Gerhard Schneider
- Department of Anesthesiology and Intensive Care, Klinikum rechts der Isar, Technical University of Munich, School of Medicine, Munich, Ismaninger Str. 22, 81675 München, Germany; (M.K.); (G.S.)
| | - Cornelius Schwarz
- Werner Reichardt Centre for Integrative Neuroscience, Eberhard-Karls-University, Otfried-Müller-Str. 25, 72076 Tübingen, Germany; (S.B.); (C.S.)
| | - Uwe Rudolph
- Department of Comparative Biosciences, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, 2001 South Lincoln Avenue, Urbana, IL 61802-6178, USA;
- Carl R. Woese Institute for Genomic Biology, University of Illiniois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Bernd Antkowiak
- Department of Anaesthesiology, Experimental Anaesthesiology Section, Eberhard-Karls-University, Waldhörnlestrasse 22, 72072 Tübingen, Germany;
| | - Berthold Drexler
- Department of Anaesthesiology, Experimental Anaesthesiology Section, Eberhard-Karls-University, Waldhörnlestrasse 22, 72072 Tübingen, Germany;
- Correspondence:
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5
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Antkowiak B, Rammes G. GABA(A) receptor-targeted drug development -New perspectives in perioperative anesthesia. Expert Opin Drug Discov 2019; 14:683-699. [DOI: 10.1080/17460441.2019.1599356] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Bernd Antkowiak
- Department of Anesthesiology and Intensive Care, Experimental Anesthesiology Section, Eberhard-Karls-University,
Tübingen, Germany
- Department of Anaesthesiology and Intensive Care, Experimental Anaesthesiology Section, Werner Reichardt Center for Integrative Neuroscience, Tübingen,
Germany
| | - Gerhard Rammes
- University Hospital rechts der Isar, Department of Anesthesiology, München,
Germany
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6
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Wasilczuk AZ, Maier KL, Kelz MB. The Mouse as a Model Organism for Assessing Anesthetic Sensitivity. Methods Enzymol 2018; 602:211-228. [PMID: 29588030 DOI: 10.1016/bs.mie.2018.01.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The mouse has been used in many medical fields as a powerful model to reveal the genetic basis of human physiology and disease. The past two decades have witnessed an enormous wealth of genetic and informatic resources dedicated to this humble organism. With the ongoing revolution in mapping neural circuitry governing behavior, the mouse is an ideal model organism poised to unravel the mysteries of general anesthetic action. This chapter will describe and provide guidelines for anesthetic phenotyping in the mouse including both motor-dependent and motor-independent assessments.
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Affiliation(s)
- Andrzej Z Wasilczuk
- University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, United States
| | - Kaitlyn L Maier
- University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, United States
| | - Max B Kelz
- University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, United States; Center for Sleep and Circadian Neurobiology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, United States.
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7
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Olufs ZPG, Loewen CA, Ganetzky B, Wassarman DA, Perouansky M. Genetic variability affects absolute and relative potencies and kinetics of the anesthetics isoflurane and sevoflurane in Drosophila melanogaster. Sci Rep 2018; 8:2348. [PMID: 29402974 PMCID: PMC5799260 DOI: 10.1038/s41598-018-20720-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 01/24/2018] [Indexed: 01/12/2023] Open
Abstract
Genetic variability affects the response to numerous xenobiotics but its role in the clinically-observed irregular responses to general anesthetics remains uncertain. To investigate the pharmacogenetics of volatile general anesthetics (VGAs), we developed a Serial Anesthesia Array apparatus to expose multiple Drosophila melanogaster samples to VGAs and behavioral assays to determine pharmacokinetic and pharmacodynamic properties of VGAs. We studied the VGAs isoflurane and sevoflurane in four wild type strains from the Drosophila Genetic Reference Panel, two commonly used laboratory strains (Canton S and w 1118 ), and a mutant in Complex I of the mitochondrial electron transport chain (ND23 60114 ). In all seven strains, isoflurane was more potent than sevoflurane, as predicted by their relative lipid solubilities, and emergence from isoflurane was slower than from sevoflurane, reproducing cardinal pharmacokinetic and pharmacodynamic properties in mammals. In addition, ND23 60114 flies were more sensitive to both agents, as observed in worms, mice, and humans carrying Complex I mutations. Moreover, we found substantial variability among the fly strains both in absolute and in relative pharmacokinetic and pharmacodynamic profiles of isoflurane and sevoflurane. These data indicate that naturally occurring genetic variations measurably influence cardinal pharmacologic properties of VGAs and that flies can be used to identify relevant genetic variations.
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Affiliation(s)
- Zachariah P G Olufs
- Department of Anesthesiology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Carin A Loewen
- Department of Genetics, College of Agriculture and Life Sciences, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Barry Ganetzky
- Department of Genetics, College of Agriculture and Life Sciences, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - David A Wassarman
- Department of Medical Genetics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Misha Perouansky
- Department of Anesthesiology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, 53706, USA.
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8
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Pal D, Silverstein BH, Sharba L, Li D, Hambrecht-Wiedbusch VS, Hudetz AG, Mashour GA. Propofol, Sevoflurane, and Ketamine Induce a Reversible Increase in Delta-Gamma and Theta-Gamma Phase-Amplitude Coupling in Frontal Cortex of Rat. Front Syst Neurosci 2017; 11:41. [PMID: 28659769 PMCID: PMC5468385 DOI: 10.3389/fnsys.2017.00041] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 05/12/2017] [Indexed: 01/12/2023] Open
Abstract
Studies from human and non-human species have demonstrated a breakdown of functional corticocortical connectivity during general anesthesia induced by anesthetics with diverse molecular, neurophysiological, and pharmacological profiles. Recent studies have demonstrated that changes in long-range neural communication, and by corollary, functional connectivity, might be influenced by cross-frequency coupling (CFC) between the phase of slow oscillations and the amplitude of local fast oscillations. Phase-amplitude coupling (PAC) between slow oscillations and alpha rhythm during general anesthesia reveal distinct patterns depending on the anesthetic. In this study, we analyzed the effect of three clinically used anesthetics (propofol: n = 6, sevoflurane: n = 10, and ketamine: n = 8) with distinct molecular mechanisms on changes in PAC in the frontal cortex of rat. The loss of righting reflex was used as a surrogate for unconsciousness. PAC was calculated using the modulation index (MI) algorithm between delta (1–4 Hz), theta (4–10 Hz), low gamma (25–55 Hz), and high gamma (65–125 Hz) bands. A linear mixed model with fixed effects was used for statistical comparisons between waking, anesthetized, and post-anesthesia recovery epochs. All three anesthetics increased the coupling between delta and low gamma (p < 0.0001) as well as between theta and low gamma (p < 0.0001) oscillations, which returned to baseline waking levels during the post-anesthetic recovery period. In addition, a reversible reduction in high gamma power (p < 0.0001) was a consistent change during anesthesia induced by all three agents. The changes in delta-high gamma and theta-high gamma PAC as well as power spectral changes in delta, theta, and low gamma bandwidths did not show a uniform response across the three anesthetics. These results encourage the study of alternative PAC patterns as drug-invariant markers of general anesthesia in humans.
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Affiliation(s)
- Dinesh Pal
- Department of Anesthesiology, University of MichiganAnn Arbor, MI, United States.,Center for Consciousness Science, University of MichiganAnn Arbor, MI, United States
| | - Brian H Silverstein
- Center for Consciousness Science, University of MichiganAnn Arbor, MI, United States.,Translational Neuroscience Program, Wayne State University School of MedicineDetroit, MI, United States
| | - Lana Sharba
- Department of Anesthesiology, University of MichiganAnn Arbor, MI, United States
| | - Duan Li
- Department of Anesthesiology, University of MichiganAnn Arbor, MI, United States.,Center for Consciousness Science, University of MichiganAnn Arbor, MI, United States
| | - Viviane S Hambrecht-Wiedbusch
- Department of Anesthesiology, University of MichiganAnn Arbor, MI, United States.,Center for Consciousness Science, University of MichiganAnn Arbor, MI, United States
| | - Anthony G Hudetz
- Department of Anesthesiology, University of MichiganAnn Arbor, MI, United States.,Center for Consciousness Science, University of MichiganAnn Arbor, MI, United States.,Neuroscience Graduate Program, University of MichiganAnn Arbor, MI, United States
| | - George A Mashour
- Department of Anesthesiology, University of MichiganAnn Arbor, MI, United States.,Center for Consciousness Science, University of MichiganAnn Arbor, MI, United States.,Neuroscience Graduate Program, University of MichiganAnn Arbor, MI, United States
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9
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Chiara DC, Jounaidi Y, Zhou X, Savechenkov PY, Bruzik KS, Miller KW, Cohen JB. General Anesthetic Binding Sites in Human α4β3δ γ-Aminobutyric Acid Type A Receptors (GABAARs). J Biol Chem 2016; 291:26529-26539. [PMID: 27821594 PMCID: PMC5159512 DOI: 10.1074/jbc.m116.753335] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 10/14/2016] [Indexed: 01/08/2023] Open
Abstract
Extrasynaptic γ-aminobutyric acid type A receptors (GABAARs),which contribute generalized inhibitory tone to the mammalian brain, are major targets for general anesthetics. To identify anesthetic binding sites in an extrasynaptic GABAAR, we photolabeled human α4β3δ GABAARs purified in detergent with [3H]azietomidate and a barbiturate, [3H]R-mTFD-MPAB, photoreactive anesthetics that bind with high selectivity to distinct but homologous intersubunit binding sites in the transmembrane domain of synaptic α1β3γ2 GABAARs. Based upon 3H incorporation into receptor subunits resolved by SDS-PAGE, there was etomidate-inhibitable labeling by [3H]azietomidate in the α4 and β3 subunits and barbiturate-inhibitable labeling by [3H]R-mTFD-MPAB in the β3 subunit. These sites did not bind the anesthetic steroid alphaxalone, which enhanced photolabeling, or DS-2, a δ subunit-selective positive allosteric modulator, which neither enhanced nor inhibited photolabeling. The amino acids labeled by [3H]azietomidate or [3H]R-mTFD-MPAB were identified by N-terminal sequencing of fragments isolated by HPLC fractionation of enzymatically digested subunits. No evidence was found for a δ subunit contribution to an anesthetic binding site. [3H]azietomidate photolabeling of β3Met-286 in βM3 and α4Met-269 in αM1 that was inhibited by etomidate but not by R-mTFD-MPAB established that etomidate binds to a site at the β3+-α4- interface equivalent to its site in α1β3γ2 GABAARs. [3H]Azietomidate and [3H]R-mTFD-MPAB photolabeling of β3Met-227 in βM1 established that these anesthetics also bind to a homologous site, most likely at the β3+-β3- interface, which suggests a subunit arrangement of β3α4β3δβ3.
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Affiliation(s)
| | - Youssef Jounaidi
- the Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts 02114, and
| | - Xiaojuan Zhou
- the Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts 02114, and
| | - Pavel Y Savechenkov
- the Department of Medicinal Chemistry and Pharmacognosy, University of Illinois, Chicago, Illinois 60612
| | - Karol S Bruzik
- the Department of Medicinal Chemistry and Pharmacognosy, University of Illinois, Chicago, Illinois 60612
| | - Keith W Miller
- the Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts 02114, and
- Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115
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10
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Cascella M, Schiavone V, Muzio MR, Cuomo A. Consciousness fluctuation during general anesthesia: a theoretical approach to anesthesia awareness and memory modulation. Curr Med Res Opin 2016; 32:1351-9. [PMID: 27046232 DOI: 10.1080/03007995.2016.1174679] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
With anesthesia awareness as a model of study we debate the both fascinating and dangerous phenomenon called consciousness fluctuation that takes place during surgical anesthesia. In accordance with current scientific knowledge this paradox is the consequence of our limits in both precise knowledge of anesthesia mechanisms and our inability to accurately assess the level of anesthesia with brain monitoring. We also focus on the relationships between memory and anesthesia, as well as the possibility of interfering with memory during general anesthesia.
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Affiliation(s)
- Marco Cascella
- a Division of Anesthesia, Department of Anesthesia, Endoscopy and Cardiology , Istituto Nazionale Tumori "Fondazione G. Pascale" - IRCCS , Naples , Italy
| | - Vincenzo Schiavone
- b Division of Anesthesia and Intensive Care , Hospital "Pineta Grande" , Castel Volturno , Italy
| | - Maria Rosaria Muzio
- c Division of Infantile Neuropsychiatry , UOMI - Maternal and Infant Health , Torre del Greco , Naples , Italy
| | - Arturo Cuomo
- a Division of Anesthesia, Department of Anesthesia, Endoscopy and Cardiology , Istituto Nazionale Tumori "Fondazione G. Pascale" - IRCCS , Naples , Italy
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11
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Jayakar SS, Zhou X, Savechenkov PY, Chiara DC, Desai R, Bruzik KS, Miller KW, Cohen JB. Positive and Negative Allosteric Modulation of an α1β3γ2 γ-Aminobutyric Acid Type A (GABAA) Receptor by Binding to a Site in the Transmembrane Domain at the γ+-β- Interface. J Biol Chem 2015; 290:23432-46. [PMID: 26229099 PMCID: PMC4645599 DOI: 10.1074/jbc.m115.672006] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Indexed: 01/24/2023] Open
Abstract
In the process of developing safer general anesthetics, isomers of anesthetic ethers and barbiturates have been discovered that act as convulsants and inhibitors of γ-aminobutyric acid type A receptors (GABAARs) rather than potentiators. It is unknown whether these convulsants act as negative allosteric modulators by binding to the intersubunit anesthetic-binding sites in the GABAAR transmembrane domain (Chiara, D. C., Jayakar, S. S., Zhou, X., Zhang, X., Savechenkov, P. Y., Bruzik, K. S., Miller, K. W., and Cohen, J. B. (2013) J. Biol. Chem. 288, 19343-19357) or to known convulsant sites in the ion channel or extracellular domains. Here, we show that S-1-methyl-5-propyl-5-(m-trifluoromethyl-diazirynylphenyl) barbituric acid (S-mTFD-MPPB), a photoreactive analog of the convulsant barbiturate S-MPPB, inhibits α1β3γ2 but potentiates α1β3 GABAAR responses. In the α1β3γ2 GABAAR, S-mTFD-MPPB binds in the transmembrane domain with high affinity to the γ(+)-β(-) subunit interface site with negative energetic coupling to GABA binding in the extracellular domain at the β(+)-α(-) subunit interfaces. GABA inhibits S-[(3)H]mTFD-MPPB photolabeling of γ2Ser-280 (γM2-15') in this site. In contrast, within the same site GABA enhances photolabeling of β3Met-227 in βM1 by an anesthetic barbiturate, R-[(3)H]methyl-5-allyl-5-(m-trifluoromethyl-diazirynylphenyl)barbituric acid (mTFD-MPAB), which differs from S-mTFD-MPPB in structure only by chirality and two hydrogens (propyl versus allyl). S-mTFD-MPPB and R-mTFD-MPAB are predicted to bind in different orientations at the γ(+)-β(-) site, based upon the distance in GABAAR homology models between γ2Ser-280 and β3Met-227. These results provide an explanation for S-mTFD-MPPB inhibition of α1β3γ2 GABAAR function and provide a first demonstration that an intersubunit-binding site in the GABAAR transmembrane domain binds negative and positive allosteric modulators.
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Affiliation(s)
| | - Xiaojuan Zhou
- the Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts 02114, and
| | - Pavel Y Savechenkov
- the Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, Illinois 60612
| | | | - Rooma Desai
- the Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts 02114, and
| | - Karol S Bruzik
- the Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, Illinois 60612
| | - Keith W Miller
- the Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts 02114, and Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115
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12
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Isoflurane anesthetic hypersensitivity and progressive respiratory depression in a mouse model with isolated mitochondrial complex I deficiency. J Anesth 2014; 28:807-14. [PMID: 24522811 DOI: 10.1007/s00540-014-1791-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Accepted: 01/10/2014] [Indexed: 12/19/2022]
Abstract
BACKGROUND Children with mitochondrial disorders are frequently anesthetized for a wide range of operations. These disorders may interfere with the response to surgery and anesthesia. We examined anesthetic sensitivity to and respiratory effects of isoflurane in the Ndufs4 knockout (KO) mouse model. These mice exhibit an isolated mitochondrial complex I (CI) deficiency of the respiratory chain, and they also display clinical signs and symptoms resembling those of patients with mitochondrial CI disease. METHODS We investigated seven Ndufs4(-/-) knockout (KO), five Ndufs4(+/-) heterozygous (HZ) and five Ndufs4(+/+) wild type (WT) mice between 22 and 25 days and again between 31 and 34 days post-natal. Animals were placed inside an airtight box, breathing spontaneously while isoflurane was administered in increasing concentrations. Minimum alveolar concentration (MAC) was determined with the bracketing study design, using the response to electrical stimulation to the hind paw. RESULTS MAC for isoflurane was significantly lower in KO mice than in HZ and WT mice: 0.81% ± 0.01 vs 1.55 ± 0.05% and 1.55 ± 0.13%, respectively, at 22-25 days, and 0.65 ± 0.05%, 1.65 ± 0.08% and 1.68 ± 0.08% at 31-34 days. The KO mice showed severe respiratory depression at lower isoflurane concentrations than the WT and HZ mice. CONCLUSION We observed an increased isoflurane anesthetic sensitivity and severe respiratory depression in the KO mice. The respiratory depression during anesthesia was strongly progressive with age. Since the pathophysiological consequences from complex I deficiency are mainly reflected in the central nervous system and our mouse model involves progressive encephalopathy, further investigation of isoflurane effects on brain mitochondrial function is warranted.
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Increased risk of awareness under anesthesia: an issue of consciousness or of memory? Anesthesiology 2014; 119:1236-8. [PMID: 24121216 DOI: 10.1097/aln.0000000000000024] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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McCarren HS, Moore JT, Kelz MB. Assessing changes in volatile general anesthetic sensitivity of mice after local or systemic pharmacological intervention. J Vis Exp 2013:e51079. [PMID: 24192721 DOI: 10.3791/51079] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
One desirable endpoint of general anesthesia is the state of unconsciousness, also known as hypnosis. Defining the hypnotic state in animals is less straightforward than it is in human patients. A widely used behavioral surrogate for hypnosis in rodents is the loss of righting reflex (LORR), or the point at which the animal no longer responds to their innate instinct to avoid the vulnerability of dorsal recumbency. We have developed a system to assess LORR in 24 mice simultaneously while carefully controlling for potential confounds, including temperature fluctuations and varying gas flows. These chambers permit reliable assessment of anesthetic sensitivity as measured by latency to return of the righting reflex (RORR) following a fixed anesthetic exposure. Alternatively, using stepwise increases (or decreases) in anesthetic concentration, the chambers also enable determination of a population's sensitivity to induction (or emergence) as measured by EC50 and Hill slope. Finally, the controlled environmental chambers described here can be adapted for a variety of alternative uses, including inhaled delivery of other drugs, toxicology studies, and simultaneous real-time monitoring of vital signs.
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Affiliation(s)
- Hilary S McCarren
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania
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Chiara DC, Jayakar SS, Zhou X, Zhang X, Savechenkov PY, Bruzik KS, Miller KW, Cohen JB. Specificity of intersubunit general anesthetic-binding sites in the transmembrane domain of the human α1β3γ2 γ-aminobutyric acid type A (GABAA) receptor. J Biol Chem 2013; 288:19343-57. [PMID: 23677991 PMCID: PMC3707639 DOI: 10.1074/jbc.m113.479725] [Citation(s) in RCA: 114] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Indexed: 11/06/2022] Open
Abstract
GABA type A receptors (GABAAR), the brain's major inhibitory neurotransmitter receptors, are the targets for many general anesthetics, including volatile anesthetics, etomidate, propofol, and barbiturates. How such structurally diverse agents can act similarly as positive allosteric modulators of GABAARs remains unclear. Previously, photoreactive etomidate analogs identified two equivalent anesthetic-binding sites in the transmembrane domain at the β(+)-α(-) subunit interfaces, which also contain the GABA-binding sites in the extracellular domain. Here, we used R-[(3)H]5-allyl-1-methyl-5-(m-trifluoromethyl-diazirynylphenyl) barbituric acid (R-mTFD-MPAB), a potent stereospecific barbiturate anesthetic, to photolabel expressed human α1β3γ2 GABAARs. Protein microsequencing revealed that R-[(3)H]mTFD-MPAB did not photolabel the etomidate sites at the β(+)-α(-) subunit interfaces. Instead, it photolabeled sites at the α(+)-β(-) and γ(+)-β(-) subunit interfaces in the transmembrane domain. On the (+)-side, α1M3 was labeled at Ala-291 and Tyr-294 and γ2M3 at Ser-301, and on the (-)-side, β3M1 was labeled at Met-227. These residues, like those in the etomidate site, are located at subunit interfaces near the synaptic side of the transmembrane domain. The selectivity of R-etomidate for the β(+)-α(-) interface relative to the α(+)-β(-)/γ(+)-β(-) interfaces was >100-fold, whereas that of R-mTFD-MPAB for its sites was >50-fold. Each ligand could enhance photoincorporation of the other, demonstrating allosteric interactions between the sites. The structural heterogeneity of barbiturate, etomidate, and propofol derivatives is accommodated by varying selectivities for these two classes of sites. We hypothesize that binding at any of these homologous intersubunit sites is sufficient for anesthetic action and that this explains to some degree the puzzling structural heterogeneity of anesthetics.
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Affiliation(s)
| | | | - Xiaojuan Zhou
- the Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts 02114, and
| | - Xi Zhang
- the Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts 02114, and
| | - Pavel Y. Savechenkov
- the Deparment of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, Illinois 60612
| | - Karol S. Bruzik
- the Deparment of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, Illinois 60612
| | - Keith W. Miller
- Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115
- the Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, Massachusetts 02114, and
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Drexler B, Zinser S, Huang S, Poe MM, Rudolph U, Cook JM, Antkowiak B. Enhancing the function of alpha5-subunit-containing GABAA receptors promotes action potential firing of neocortical neurons during up-states. Eur J Pharmacol 2013; 703:18-24. [PMID: 23380687 DOI: 10.1016/j.ejphar.2013.01.034] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Revised: 01/12/2013] [Accepted: 01/16/2013] [Indexed: 11/27/2022]
Abstract
Neocortical neurons mediate the sedative and anticonvulsant properties of benzodiazepines. These agents enhance synaptic inhibition via positive modulation of γ-aminobutyric acid (GABAA) receptors harboring α1-, α2-, α3- or α5-protein subunits. Benzodiazepine-sensitive GABAA receptors containing the α5-subunit are abundant in the neocortex, but their impact in controlling neuronal firing patterns is unknown. Here we studied how the discharge rates of cortical neurons are modified by a positive (SH-053-2'F-R-CH3) and a negative (L 655,708) α5-subunit-preferring allosteric modulator in comparison to diazepam, the classical non-selective benzodiazepine. Drug actions were characterized in slice cultures from wild-type and α5(H105R) knock-in mice by performing extracellular multi-unit-recordings. In knock-in mice, receptors containing the α5 subunit are insensitive to benzodiazepines. The non-selective positive allosteric modulator diazepam decreased the discharge rates of neocortical neurons during episodes of ongoing neuronal activity (up states). In contrast to diazepam, the α5-preferring positive modulator SH-053-2'F-R-CH3 accelerated action potential firing during up states. This promoting action was absent in slices from α5(H105R) mice, confirming that it is mediated by the α5-subunit. Consistent with these observations, the negative α5-selective modulator L 655,708 inhibited up state action potential activity in slices from wild-type mice. The opposing actions of diazepam and SH-053-2'F-R-CH3, which both enhance GABAA receptor function but differ in subtype-selectivity, uncovers contrasting roles of GABAA receptor subtypes in controlling the firing rates of cortical neurons. These findings may have important implications for the design of novel anaesthetic and anticonvulsant benzodiazepines displaying an improved efficacy and fewer side effects.
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Affiliation(s)
- Berthold Drexler
- Experimental Anaesthesiology Section, Department of Anaesthesiology and Intensive Care Medicine, Eberhard-Karls-University, 72072 Tuebingen, Germany.
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Savechenkov PY, Zhang X, Chiara DC, Stewart DS, Ge R, Zhou X, Raines DE, Cohen JB, Forman SA, Miller KW, Bruzik KS. Allyl m-trifluoromethyldiazirine mephobarbital: an unusually potent enantioselective and photoreactive barbiturate general anesthetic. J Med Chem 2012; 55:6554-65. [PMID: 22734650 DOI: 10.1021/jm300631e] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
We synthesized 5-allyl-1-methyl-5-(m-trifluoromethyl-diazirynylphenyl)barbituric acid (14), a trifluoromethyldiazirine-containing derivative of general anesthetic mephobarbital, separated the racemic mixture into enantiomers by chiral chromatography, and determined the configuration of the (+)-enantiomer as S by X-ray crystallography. Additionally, we obtained the (3)H-labeled ligand with high specific radioactivity. R-(-)-14 is an order of magnitude more potent than the most potent clinically used barbiturate, thiopental, and its general anesthetic EC(50) approaches those for propofol and etomidate, whereas S-(+)-14 is 10-fold less potent. Furthermore, at concentrations close to its anesthetic potency, R-(-)-14 both potentiated GABA-induced currents and increased the affinity for the agonist muscimol in human α1β2/3γ2L GABA(A) receptors. Finally, R-(-)-14 was found to be an exceptionally efficient photolabeling reagent, incorporating into both α1 and β3 subunits of human α1β3 GABA(A) receptors. These results indicate R-(-)-14 is a functional general anesthetic that is well-suited for identifying barbiturate binding sites on Cys-loop receptors.
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Affiliation(s)
- Pavel Y Savechenkov
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, 32 Fruit Street, Boston, MA 02114, USA
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Current World Literature. Curr Opin Cardiol 2012; 27:318-26. [DOI: 10.1097/hco.0b013e328352dfaf] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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