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Wei X, Campagna JJ, Jagodzinska B, Wi D, Cohn W, Lee JT, Zhu C, Huang CS, Molnár L, Houser CR, John V, Mody I. A therapeutic small molecule enhances γ-oscillations and improves cognition/memory in Alzheimer's disease model mice. Proc Natl Acad Sci U S A 2024; 121:e2400420121. [PMID: 39106304 DOI: 10.1073/pnas.2400420121] [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: 01/08/2024] [Accepted: 07/08/2024] [Indexed: 08/09/2024] Open
Abstract
Brain rhythms provide the timing for recruitment of brain activity required for linking together neuronal ensembles engaged in specific tasks. The γ-oscillations (30 to 120 Hz) orchestrate neuronal circuits underlying cognitive processes and working memory. These oscillations are reduced in numerous neurological and psychiatric disorders, including early cognitive decline in Alzheimer's disease (AD). Here, we report on a potent brain-permeable small molecule, DDL-920 that increases γ-oscillations and improves cognition/memory in a mouse model of AD, thus showing promise as a class of therapeutics for AD. We employed anatomical, in vitro and in vivo electrophysiological, and behavioral methods to examine the effects of our lead therapeutic candidate small molecule. As a novel in central nervous system pharmacotherapy, our lead molecule acts as a potent, efficacious, and selective negative allosteric modulator of the γ-aminobutyric acid type A receptors most likely assembled from α1β2δ subunits. These receptors, identified through anatomical and pharmacological means, underlie the tonic inhibition of parvalbumin (PV) expressing interneurons (PV+INs) critically involved in the generation of γ-oscillations. When orally administered twice daily for 2 wk, DDL-920 restored the cognitive/memory impairments of 3- to 4-mo-old AD model mice as measured by their performance in the Barnes maze. Our approach is unique as it is meant to enhance cognitive performance and working memory in a state-dependent manner by engaging and amplifying the brain's endogenous γ-oscillations through enhancing the function of PV+INs.
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Affiliation(s)
- Xiaofei Wei
- Department of Neurology, The David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA 90095
- Department of Neurosurgery, The David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA 90095
| | - Jesus J Campagna
- Department of Neurology, Drug Development Laboratory, Mary S. Easton Center for Alzheimer's Disease Research and Care, The David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA 90095
| | - Barbara Jagodzinska
- Department of Neurology, Drug Development Laboratory, Mary S. Easton Center for Alzheimer's Disease Research and Care, The David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA 90095
| | - Dongwook Wi
- Department of Neurology, Drug Development Laboratory, Mary S. Easton Center for Alzheimer's Disease Research and Care, The David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA 90095
| | - Whitaker Cohn
- Department of Neurology, Drug Development Laboratory, Mary S. Easton Center for Alzheimer's Disease Research and Care, The David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA 90095
| | - Jessica T Lee
- Department of Neurology, Drug Development Laboratory, Mary S. Easton Center for Alzheimer's Disease Research and Care, The David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA 90095
| | - Chunni Zhu
- Department of Neurology, Drug Development Laboratory, Mary S. Easton Center for Alzheimer's Disease Research and Care, The David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA 90095
| | - Christine S Huang
- Department of Neurobiology, The David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA 90095
| | - László Molnár
- Department of Electrical Engineering, Sapientia Hungarian University of Transylvania, Târgu Mureş 540485, Romania
| | - Carolyn R Houser
- Department of Neurobiology, The David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA 90095
| | - Varghese John
- Department of Neurology, Drug Development Laboratory, Mary S. Easton Center for Alzheimer's Disease Research and Care, The David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA 90095
| | - Istvan Mody
- Department of Neurology, The David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA 90095
- Department of Physiology, The David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA 90095
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Granados-Fuentes D, Lambert P, Simon T, Mennerick S, Herzog ED. GABA A receptor subunit composition regulates circadian rhythms in rest-wake and synchrony among cells in the suprachiasmatic nucleus. Proc Natl Acad Sci U S A 2024; 121:e2400339121. [PMID: 39047036 PMCID: PMC11295074 DOI: 10.1073/pnas.2400339121] [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: 01/10/2024] [Accepted: 06/24/2024] [Indexed: 07/27/2024] Open
Abstract
The mammalian circadian clock located in the suprachiasmatic nucleus (SCN) produces robust daily rhythms including rest-wake. SCN neurons synthesize and respond to γ-aminobutyric acid (GABA), but its role remains unresolved. We tested the hypothesis that γ2- and δ-subunits of the GABAA receptor in the SCN differ in their regulation of synchrony among circadian cells. We used two approaches: 1) shRNA to knock-down (KD) the expression of either γ2 or δ subunits in the SCN or 2) knock-in mice harboring a point mutation in the M2 domains of the endogenous GABAA γ2 or δ subunits. KD of either γ2 or δ subunits in the SCN increased daytime running and reduced nocturnal running by reducing their circadian amplitude by a third. Similarly, δ subunit knock-in mice showed decreased circadian amplitude, increased duration of daily activity, and decreased total daily activity. Reduction, or mutation of either γ2 or δ subunits halved the synchrony among, and amplitude of, circadian SCN cells as measured by firing rate or expression of the PERIOD2 protein, in vitro. Surprisingly, overexpression of the γ2 subunit rescued these phenotypes following KD or mutation of the δ subunit, and overexpression of the δ subunit rescued deficiencies due to γ2 subunit KD or mutation. We conclude that γ2 and δ GABAA receptor subunits play similar roles in maintaining circadian synchrony in the SCN and amplitude of daily rest-wake rhythms, but that modulation of their relative densities can change the duration and amplitude of daily activities.
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Affiliation(s)
| | - Peter Lambert
- Department of Psychiatry, Washington University in St. Louis, MO63130-4899
| | - Tatiana Simon
- Department of Biology, Washington University in St. Louis, MO63130-4899
| | - Steven Mennerick
- Department of Psychiatry, Washington University in St. Louis, MO63130-4899
| | - Erik D. Herzog
- Department of Biology, Washington University in St. Louis, MO63130-4899
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Zavalin K, Hassan A, Zhang Y, Khera Z, Lagrange AH. Region and layer-specific expression of GABA A receptor isoforms and KCC2 in developing cortex. Front Cell Neurosci 2024; 18:1390742. [PMID: 38894703 PMCID: PMC11184147 DOI: 10.3389/fncel.2024.1390742] [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: 02/23/2024] [Accepted: 05/13/2024] [Indexed: 06/21/2024] Open
Abstract
Introduction γ-Aminobutyric acid (GABA) type A receptors (GABAARs) are ligand-gated Cl-channels that mediate the bulk of inhibitory neurotransmission in the mature CNS and are targets of many drugs. During cortical development, GABAAR-mediated signals are significantly modulated by changing subunit composition and expression of Cl-transporters as part of developmental processes and early network activity. To date, this developmental evolution has remained understudied, particularly at the level of cortical layer-specific changes. In this study, we characterized the expression of nine major GABAAR subunits and K-Cl transporter 2 (KCC2) in mouse somatosensory cortex from embryonic development to postweaning maturity. Methods We evaluated expression of α1-5, β2-3, γ2, and δ GABAAR subunits using immunohistochemistry and Western blot techniques, and expression of KCC2 using immunohistochemistry in cortices from E13.5 to P25 mice. Results We found that embryonic cortex expresses mainly α3, α5, β3, and γ2, while expression of α1, α2, α4, β2, δ, and KCC2 begins at later points in development; however, many patterns of nuanced expression can be found in specific lamina, cortical regions, and cells and structures. Discussion While the general pattern of expression of each subunit and KCC2 is similar to previous studies, we found a number of unique temporal, regional, and laminar patterns that were previously unknown. These findings provide much needed knowledge of the intricate developmental evolution in GABAAR composition and KCC2 expression to accommodate developmental signals that transition to mature neurotransmission.
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Affiliation(s)
- Kirill Zavalin
- Department of Neurology, Vanderbilt University School of Medicine, Nashville, TN, United States
| | - Anjana Hassan
- Department of Neurology, Vanderbilt University School of Medicine, Nashville, TN, United States
| | - Yueli Zhang
- Department of Neurology, Vanderbilt University School of Medicine, Nashville, TN, United States
| | - Zain Khera
- Department of Neurology, Vanderbilt University School of Medicine, Nashville, TN, United States
| | - Andre H. Lagrange
- Department of Neurology, Vanderbilt University School of Medicine, Nashville, TN, United States
- Department of Neurology, TVH VA Medical Center, Nashville, TN, United States
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Lambert PM, Salvatore SV, Lu X, Shu HJ, Benz A, Rensing N, Yuede CM, Wong M, Zorumski CF, Mennerick S. A role for δ subunit-containing GABA A receptors on parvalbumin positive neurons in maintaining electrocortical signatures of sleep states. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.25.586604. [PMID: 38585911 PMCID: PMC10996536 DOI: 10.1101/2024.03.25.586604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
GABA A receptors containing δ subunits have been shown to mediate tonic/slow inhibition in the CNS. These receptors are typically found extrasynaptically and are activated by relatively low levels of ambient GABA in the extracellular space. In the mouse neocortex, δ subunits are expressed on the surface of some pyramidal cells as well as on parvalbumin positive (PV+) interneurons. An important function of PV+ interneurons is the organization of coordinated network activity that can be measured by EEG; however, it remains unclear what role tonic/slow inhibitory control of PV+ neurons may play in shaping oscillatory activity. After confirming a loss of functional δ mediated tonic currents in PV cells in cortical slices from mice lacking Gabrd in PV+ neurons (PV δcKO), we performed EEG recordings to survey network activity across wake and sleep states. PV δcKO mice showed altered spectral content of EEG during NREM and REM sleep that was a result of increased oscillatory activity in NREM and the emergence of transient high amplitude bursts of theta frequency activity during REM. Viral reintroduction of Gabrd to PV+ interneurons in PV δcKO mice rescued REM EEG phenotypes, supporting an important role for δ subunit mediated inhibition of PV+ interneurons for maintaining normal REM cortical oscillations. Significance statement The impact on cortical EEG of inhibition on PV+ neurons was studied by deleting a GABA A receptor subunit selectively from these neurons. We discovered unexpected changes at low frequencies during sleep that were rescued by viral reintroduction.
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Uusi-Oukari M, Korpi ER. GABAergic mechanisms in alcohol dependence. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2024; 175:75-123. [PMID: 38555121 DOI: 10.1016/bs.irn.2024.03.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/02/2024]
Abstract
The target of alcohol's effect on the central nervous system has been sought for more than 50 years in the brain's GABA system. The behavioral and emotional effects of alcohol in humans and rodents are very similar to those of barbiturates and benzodiazepines, and GABAA receptors have been shown to be one of the sites of alcohol action. The mechanisms of GABAergic inhibition have been a hotspot of research but have turned out to be complex and controversial. Genetics support the involvement of some GABAA receptor subunits in the development of alcohol dependence and in alcohol use disorders (AUD). Since the effect of alcohol on the GABAA system resembles that of a GABAergic positive modulator, it may be possible to develop GABAergic drug treatments that could substitute for alcohol. The adaptation mechanisms of the GABA system and the plasticity of the brain are a big challenge for drug development: the drugs that act on GABAA receptors developed so far also may cause adaptation and development of additional addiction. Human polymorphisms should be studied further to get insight about how they affect receptor function, expression or other factors to make reasonable predictions/hypotheses about what non-addictive interventions would help in alcohol dependence and AUD.
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Affiliation(s)
- Mikko Uusi-Oukari
- Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, Turku, Finland
| | - Esa R Korpi
- Department of Pharmacology, Faculty of Medicine, University of Helsinki, Helsinki, Finland.
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DiLeo A, Antonodiou P, Blandino K, Conlin E, Melón L, Maguire JL. Network States in the Basolateral Amygdala Predicts Voluntary Alcohol Consumption. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.06.21.545962. [PMID: 38464012 PMCID: PMC10925084 DOI: 10.1101/2023.06.21.545962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
Although most adults in the United States will drink alcohol in their life, only about 6% will go on to develop an alcohol use disorder (AUD). While a great deal of work has furthered our understanding of the cycle of addiction, it remains unclear why certain people transition to disordered drinking. Altered activity in regions implicated in AUDs, like the basolateral amygdala (BLA), has been suggested to play a role in the pathophysiology of AUDs, but how these networks contribute to alcohol misuse remains unclear. Our recent work demonstrated that alcohol can modulate BLA network states and that GABAergic parvalbumin (PV) interneurons are crucial modulators of network activity in the BLA. Further, our lab has demonstrated that δ subunit-containing GABA A receptors, which are modulated by alcohol, are highly expressed on PV interneurons in the BLA. These receptors on PV interneurons have also been shown to influence alcohol intake in a voluntary binge drinking paradigm and anxiety-like behavior in withdrawal. Therefore, we hypothesized that alcohol may impact BLA network states via δ subunit-containing GABA A receptors on PV interneurons to impact the extent of alcohol use. To test this hypothesis, we measured the impact of acute alcohol exposure on oscillatory states in the basolateral amygdala and then assessed the relationship to the extent of voluntary ethanol consumption in the Intermittent Access, Drinking-in-the-Dark-Multiple Scheduled Access, and Chronic Intermittent Ethanol exposure paradigms. Remarkably, we demonstrate that the average alcohol intake negatively correlates with δ subunit-containing GABA A receptor expression on PV interneurons and gamma power in the BLA after the first exposure to alcohol. These data implicate δ subunit-containing GABA A receptor expression on PV interneurons in the BLA in voluntary alcohol intake and suggest that BLA network states may serve as a useful biomarker for those at risk for alcohol misuse. Significance Statement Oscillatory states in the BLA have been demonstrated to drive behavioral states involved in emotional processing, including negative valence processing. Given that negative emotional states/hyperkatifeia contribute to the cycle of AUDs, our previous work demonstrating the ability of alcohol to modulate BLA network states and thereby behavioral states suggests that this mechanism may influence alcohol intake. Here we demonstrate a relationship between the ability of alcohol to modulate oscillations in the BLA and future alcohol intake such that the extent to which alcohol influences BLA network states predict the extent of future voluntary alcohol intake. These findings suggest that individual variability in the sensitivity of the BLA network to alcohol influences voluntary alcohol consumption.
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Liddiard GT, Suryavanshi PS, Glykys J. Enhancing GABAergic Tonic Inhibition Reduces Seizure-Like Activity in the Neonatal Mouse Hippocampus and Neocortex. J Neurosci 2024; 44:e1342232023. [PMID: 38176909 PMCID: PMC10869160 DOI: 10.1523/jneurosci.1342-23.2023] [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: 07/17/2023] [Revised: 11/27/2023] [Accepted: 12/21/2023] [Indexed: 01/06/2024] Open
Abstract
Approximately one-third of neonatal seizures do not respond to first-line anticonvulsants, including phenobarbital, which enhances phasic inhibition. Whether enhancing tonic inhibition decreases seizure-like activity in the neonate when GABA is mainly depolarizing at this age is unknown. We evaluated if increasing tonic inhibition using THIP [4,5,6,7-tetrahydroisoxazolo(5,4-c)pyridin-3-ol, gaboxadol], a δ-subunit-selective GABAA receptor agonist, decreases seizure-like activity in neonatal C57BL/6J mice (postnatal day P5-8, both sexes) using acute brain slices. Whole-cell patch-clamp recordings showed that THIP enhanced GABAergic tonic inhibitory conductances in layer V neocortical and CA1 pyramidal neurons and increased their rheobase without altering sEPSC characteristics. Two-photon calcium imaging demonstrated that enhancing the activity of extrasynaptic GABAARs decreased neuronal firing in both brain regions. In the 4-aminopyridine and the low-Mg2+ model of pharmacoresistant seizures, THIP reduced epileptiform activity in the neocortex and CA1 hippocampal region of neonatal and adult brain slices in a dose-dependent manner. We conclude that neocortical layer V and CA1 pyramidal neurons have tonic inhibitory conductances, and when enhanced, they reduce neuronal firing and decrease seizure-like activity. Therefore, augmenting tonic inhibition could be a viable approach for treating neonatal seizures.
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Affiliation(s)
- G T Liddiard
- Stead Family Department of Pediatrics, Iowa Neuroscience Institute, The University of Iowa, Iowa City 52242, Iowa
- Interdisciplinary Graduate Program in Neuroscience, The University of Iowa, Iowa City 52242, Iowa
| | - P S Suryavanshi
- Stead Family Department of Pediatrics, Iowa Neuroscience Institute, The University of Iowa, Iowa City 52242, Iowa
| | - J Glykys
- Stead Family Department of Pediatrics, Iowa Neuroscience Institute, The University of Iowa, Iowa City 52242, Iowa
- Interdisciplinary Graduate Program in Neuroscience, The University of Iowa, Iowa City 52242, Iowa
- Department of Neurology, The University of Iowa, Iowa City 52242, Iowa
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Maguire JL, Mennerick S. Neurosteroids: mechanistic considerations and clinical prospects. Neuropsychopharmacology 2024; 49:73-82. [PMID: 37369775 PMCID: PMC10700537 DOI: 10.1038/s41386-023-01626-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 04/15/2023] [Accepted: 05/17/2023] [Indexed: 06/29/2023]
Abstract
Like other classes of treatments described in this issue's section, neuroactive steroids have been studied for decades but have risen as a new class of rapid-acting, durable antidepressants with a distinct mechanism of action from previous antidepressant treatments and from other compounds covered in this issue. Neuroactive steroids are natural derivatives of progesterone but are proving effective as exogenous treatments. The best understood mechanism is that of positive allosteric modulation of GABAA receptors, where subunit selectivity may promote their profile of action. Mechanistically, there is some reason to think that neuroactive steroids may separate themselves from liabilities of other GABA modulators, although research is ongoing. It is also possible that intracellular targets, including inflammatory pathways, may be relevant to beneficial actions. Strengths and opportunities for further development include exploiting non-GABAergic targets, structural analogs, enzymatic production of natural steroids, precursor loading, and novel formulations. The molecular mechanisms of behavioral effects are not fully understood, but study of brain network states involved in emotional processing demonstrate a robust influence on affective states not evident with at least some other GABAergic drugs including benzodiazepines. Ongoing studies with neuroactive steroids will further elucidate the brain and behavioral effects of these compounds as well as likely underpinnings of disease.
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Affiliation(s)
- Jamie L Maguire
- Department of Neuroscience, Tufts University School of Medicine, 136 Harrison Ave, Boston, MA, 02111, USA
| | - Steven Mennerick
- Department of Psychiatry and Taylor Family Institute for Innovative Psychiatric Research, Washington University in St. Louis School of Medicine, 660 S. Euclid Ave., St. Louis, MO, 63110, USA.
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McGurrin P, Norato G, Thompson-Westra J, McCrossin G, Lines E, Lungu C, Pandey S, Tinaz S, Voller B, Ramchandani V, Hallett M, Haubenberger D. Objective response to ethanol in essential tremor: results from a standardized ethanol challenge study. Ann Clin Transl Neurol 2024; 11:156-168. [PMID: 38087917 PMCID: PMC10791018 DOI: 10.1002/acn3.51943] [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: 10/04/2023] [Accepted: 10/29/2023] [Indexed: 01/17/2024] Open
Abstract
BACKGROUND AND OBJECTIVES Ethanol has been reported to improve tremor severity in approximately two thirds of patients with essential tremor (ET), but the accuracy of that proportion is not certain and the mechanism of action is unknown. The goal of this study was to investigate alcohol response on tremor by applying an a priori objective response definition and subsequently to describe the responder rate to a standardized ethanol dose in a cohort of 85 ET patients. A secondary analysis evaluated other tremor and nontremor features, including demographics, tremor intensity, breath alcohol concentration, nontremor effects of alcohol, self-reported responder status to ethanol, and prior ethanol exposure. METHODS This was a prospective, open-label, single-dose challenge of oral ethanol during which motor and nonmotor measurements were obtained starting immediately prior to ethanol administration and subsequently every 20 min for 120 min. We defined tremor reduction as a 35% decline in power in the patient's tremor frequency recorded during spiral drawing 60 min after ethanol administration. RESULTS In total, 80% of patients were considered alcohol responsive using our objective definition. Responder status and change in the objective tremor metrics were significantly correlated with the change in breath alcohol concentration levels after ethanol administration, but no other relationships to nontremor metrics were found. DISCUSSION A high percentage of patients actually respond to acute ethanol. However, their self-reported response does not correlate well with their objective response. Objective response correlates with breath alcohol level but not with sedation, indicating a specific effect of ethanol on tremor.
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Affiliation(s)
- Patrick McGurrin
- Office of the Senior Vice President and Provost, University of Maryland, College Park, Maryland, USA
- Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Gina Norato
- Office of the Clinical Director, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Johanna Thompson-Westra
- Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
- Department of Family Medicine, University of Colorado Anschutz, Aurora, Colorado, USA
| | - Gayle McCrossin
- Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
- Department of Rehabilitation Medicine, Office of Strategic Research, Applied Physiology and Exercise Science Lab, National Institutes of Health, Bethesda, Maryland, USA
| | - Emily Lines
- Department of Family Medicine, University of Colorado Anschutz, Aurora, Colorado, USA
| | - Codrin Lungu
- Division of Clinical Research, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Sanjay Pandey
- Department of Neurology and Stroke Medicine, Amrita Hospital, Faridabad, India
| | - Sule Tinaz
- Department of Neurology, Yale School of Medicine, New Haven, Connecticut, USA
| | | | - Vijay Ramchandani
- Human Psychopharmacology Laboratory, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland, USA
| | - Mark Hallett
- Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
| | - Dietrich Haubenberger
- Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
- Office of the Clinical Director, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
- Department of Neurosciences, University of San Diego California, La Jolla, California, USA
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10
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Wei X, Campagna JJ, Jagodzinska B, Wi D, Cohn W, Lee J, Zhu C, Huang CS, Molnár L, Houser CR, John V, Mody I. A therapeutic small molecule lead enhances γ-oscillations and improves cognition/memory in Alzheimer's disease model mice. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.04.569994. [PMID: 38106006 PMCID: PMC10723366 DOI: 10.1101/2023.12.04.569994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
Brain rhythms provide the timing and concurrence of brain activity required for linking together neuronal ensembles engaged in specific tasks. In particular, the γ-oscillations (30-120 Hz) orchestrate neuronal circuits underlying cognitive processes and working memory. These oscillations are reduced in numerous neurological and psychiatric disorders, including early cognitive decline in Alzheimer's disease (AD). Here we report on a potent brain permeable small molecule, DDL-920 that increases γ-oscillations and improves cognition/memory in a mouse model of AD, thus showing promise as a new class of therapeutics for AD. As a first in CNS pharmacotherapy, our lead candidate acts as a potent, efficacious, and selective negative allosteric modulator (NAM) of the γ-aminobutyric acid type A receptors (GABA A Rs) assembled from α1β2δ subunits. We identified these receptors through anatomical and pharmacological means to mediate the tonic inhibition of parvalbumin (PV) expressing interneurons (PV+INs) critically involved in the generation of γ-oscillations. Our approach is unique as it is meant to enhance cognitive performance and working memory in a state-dependent manner by engaging and amplifying the brain's endogenous γ-oscillations through enhancing the function of PV+INs.
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11
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Abstract
Ethanol (EtOH) has effects on numerous cellular molecular targets, and alterations in synaptic function are prominent among these effects. Acute exposure to EtOH activates or inhibits the function of proteins involved in synaptic transmission, while chronic exposure often produces opposing and/or compensatory/homeostatic effects on the expression, localization, and function of these proteins. Interactions between different neurotransmitters (e.g., neuropeptide effects on release of small molecule transmitters) can also influence both acute and chronic EtOH actions. Studies in intact animals indicate that the proteins affected by EtOH also play roles in the neural actions of the drug, including acute intoxication, tolerance, dependence, and the seeking and drinking of EtOH. The present chapter is an update of our previous Lovinger and Roberto (Curr Top Behav Neurosci 13:31-86, 2013) chapter and reviews the literature describing these acute and chronic synaptic effects of EtOH with a focus on adult animals and their relevance for synaptic transmission, plasticity, and behavior.
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Affiliation(s)
- David M Lovinger
- Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism (NIAAA), Rockville, MD, USA
| | - Marisa Roberto
- Molecular Medicine Department, Scripps Research Institute, La Jolla, CA, USA.
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12
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Spectrin-beta 2 facilitates the selective accumulation of GABA A receptors at somatodendritic synapses. Commun Biol 2023; 6:11. [PMID: 36604600 PMCID: PMC9816108 DOI: 10.1038/s42003-022-04381-x] [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: 03/05/2022] [Accepted: 12/14/2022] [Indexed: 01/07/2023] Open
Abstract
Fast synaptic inhibition is dependent on targeting specific GABAAR subtypes to dendritic and axon initial segment (AIS) synapses. Synaptic GABAARs are typically assembled from α1-3, β and γ subunits. Here, we isolate distinct GABAARs from the brain and interrogate their composition using quantitative proteomics. We show that α2-containing receptors co-assemble with α1 subunits, whereas α1 receptors can form GABAARs with α1 as the sole α subunit. We demonstrate that α1 and α2 subunit-containing receptors co-purify with distinct spectrin isoforms; cytoskeletal proteins that link transmembrane proteins to the cytoskeleton. β2-spectrin was preferentially associated with α1-containing GABAARs at dendritic synapses, while β4-spectrin was associated with α2-containing GABAARs at AIS synapses. Ablating β2-spectrin expression reduced dendritic and AIS synapses containing α1 but increased the number of synapses containing α2, which altered phasic inhibition. Thus, we demonstrate a role for spectrins in the synapse-specific targeting of GABAARs, determining the efficacy of fast neuronal inhibition.
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13
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Lambert PM, Ni R, Benz A, Rensing NR, Wong M, Zorumski CF, Mennerick S. Non-sedative cortical EEG signatures of allopregnanolone and functional comparators. Neuropsychopharmacology 2023; 48:371-379. [PMID: 36168047 PMCID: PMC9751067 DOI: 10.1038/s41386-022-01450-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 08/13/2022] [Accepted: 08/31/2022] [Indexed: 12/26/2022]
Abstract
Neurosteroids that positively modulate GABAA receptors are among a growing list of rapidly acting antidepressants, including ketamine and psychedelics. To develop increasingly specific treatments with fewer side effects, we explored the possibility of EEG signatures in mice, which could serve as a cross-species screening tool. There are few studies of the impact of non-sedative doses of rapid antidepressants on EEG in either rodents or humans. Here we hypothesize that EEG features may separate a rapid antidepressant neurosteroid, allopregnanolone, from other GABAA positive modulators, pentobarbital and diazepam. Further, we compared the actions GABA modulators with those of ketamine, an NMDA antagonist and prototype rapid antidepressant. We examined EEG spectra during active exploration at two cortical locations and examined cross-regional and cross-frequency interactions. We found that at comparable doses, the effects of allopregnanolone, despite purported selectivity for certain GABAAR subtypes, was indistinguishable from pentobarbital during active waking exploration. The actions of diazepam had recognizable common features with allopregnanolone and pentobarbital but was also distinct, consistent with subunit selectivity of benzodiazepines. Finally, ketamine exhibited no distinguishing overlap with allopregnanolone in the parameters examined. Our results suggest that rapid antidepressants with different molecular substrates may remain separated at the level of large-scale ensemble activity, but the studies leave open the possibility of commonalities in more discrete circuits and/or in the context of a dysfunctional brain.
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Affiliation(s)
- Peter M Lambert
- Department of Psychiatry, Washington University in St. Louis School of Medicine, 660S. Euclid Ave., MSC 8134-0181-0G, St. Louis, MO, 63110, USA.,Medical Scientist Training Program, Washington University in St. Louis School of Medicine, 660S. Euclid Ave., MSC 8134-0181-0G, St. Louis, MO, 63110, USA
| | - Richard Ni
- Department of Psychiatry, Washington University in St. Louis School of Medicine, 660S. Euclid Ave., MSC 8134-0181-0G, St. Louis, MO, 63110, USA
| | - Ann Benz
- Department of Psychiatry, Washington University in St. Louis School of Medicine, 660S. Euclid Ave., MSC 8134-0181-0G, St. Louis, MO, 63110, USA
| | - Nicholas R Rensing
- Department of Neurology, Washington University in St. Louis School of Medicine, 660S. Euclid Ave., MSC 8134-0181-0G, St. Louis, MO, 63110, USA
| | - Michael Wong
- Department of Neurology, Washington University in St. Louis School of Medicine, 660S. Euclid Ave., MSC 8134-0181-0G, St. Louis, MO, 63110, USA
| | - Charles F Zorumski
- Department of Psychiatry, Washington University in St. Louis School of Medicine, 660S. Euclid Ave., MSC 8134-0181-0G, St. Louis, MO, 63110, USA.,Taylor Family Institute for Innovative Psychiatric Research, Washington University in St. Louis School of Medicine, 660S. Euclid Ave., MSC 8134-0181-0G, St. Louis, MO, 63110, USA
| | - Steven Mennerick
- Department of Psychiatry, Washington University in St. Louis School of Medicine, 660S. Euclid Ave., MSC 8134-0181-0G, St. Louis, MO, 63110, USA. .,Taylor Family Institute for Innovative Psychiatric Research, Washington University in St. Louis School of Medicine, 660S. Euclid Ave., MSC 8134-0181-0G, St. Louis, MO, 63110, USA.
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14
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Choi C, Smalley JL, Lemons AHS, Ren Q, Bope CE, Dengler JS, Davies PA, Moss SJ. Analyzing the mechanisms that facilitate the subtype-specific assembly of γ-aminobutyric acid type A receptors. Front Mol Neurosci 2022; 15:1017404. [PMID: 36263376 PMCID: PMC9574402 DOI: 10.3389/fnmol.2022.1017404] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 09/07/2022] [Indexed: 01/16/2023] Open
Abstract
Impaired inhibitory signaling underlies the pathophysiology of many neuropsychiatric and neurodevelopmental disorders including autism spectrum disorders and epilepsy. Neuronal inhibition is regulated by synaptic and extrasynaptic γ-aminobutyric acid type A receptors (GABA A Rs), which mediate phasic and tonic inhibition, respectively. These two GABA A R subtypes differ in their function, ligand sensitivity, and physiological properties. Importantly, they contain different α subunit isoforms: synaptic GABA A Rs contain the α1-3 subunits whereas extrasynaptic GABA A Rs contain the α4-6 subunits. While the subunit composition is critical for the distinct roles of synaptic and extrasynaptic GABA A R subtypes in inhibition, the molecular mechanism of the subtype-specific assembly has not been elucidated. To address this issue, we purified endogenous α1- and α4-containing GABA A Rs from adult murine forebrains and examined their subunit composition and interacting proteins using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) and quantitative analysis. We found that the α1 and α4 subunits form separate populations of GABA A Rs and interact with distinct sets of binding proteins. We also discovered that the β3 subunit, which co-purifies with both the α1 and α4 subunits, has different levels of phosphorylation on serines 408 and 409 (S408/9) between the two receptor subtypes. To understand the role S408/9 plays in the assembly of α1- and α4-containing GABA A Rs, we examined the effects of S408/9A (alanine) knock-in mutation on the subunit composition of the two receptor subtypes using LC-MS/MS and quantitative analysis. We discovered that the S408/9A mutation results in the formation of novel α1α4-containing GABA A Rs. Moreover, in S408/9A mutants, the plasma membrane expression of the α4 subunit is increased whereas its retention in the endoplasmic reticulum is reduced. These findings suggest that S408/9 play a critical role in determining the subtype-specific assembly of GABA A Rs, and thus the efficacy of neuronal inhibition.
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Affiliation(s)
- Catherine Choi
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, United States
| | - Joshua L. Smalley
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, United States
| | - Abigail H. S. Lemons
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, United States
| | - Qiu Ren
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, United States
| | - Christopher E. Bope
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, United States
| | - Jake S. Dengler
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, United States
| | - Paul A. Davies
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, United States
| | - Stephen J. Moss
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, United States,Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom,*Correspondence: Stephen J. Moss,
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15
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Fish KN, Joffe ME. Targeting prefrontal cortex GABAergic microcircuits for the treatment of alcohol use disorder. Front Synaptic Neurosci 2022; 14:936911. [PMID: 36105666 PMCID: PMC9465392 DOI: 10.3389/fnsyn.2022.936911] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Accepted: 07/27/2022] [Indexed: 11/17/2022] Open
Abstract
Developing novel treatments for alcohol use disorders (AUDs) is of paramount importance for improving patient outcomes and alleviating the suffering related to the disease. A better understanding of the molecular and neurocircuit mechanisms through which alcohol alters brain function will be instrumental in the rational development of new efficacious treatments. Clinical studies have consistently associated the prefrontal cortex (PFC) function with symptoms of AUDs. Population-level analyses have linked the PFC structure and function with heavy drinking and/or AUD diagnosis. Thus, targeting specific PFC cell types and neural circuits holds promise for the development of new treatments. Here, we overview the tremendous diversity in the form and function of inhibitory neuron subtypes within PFC and describe their therapeutic potential. We then summarize AUD population genetics studies, clinical neurophysiology findings, and translational neuroscience discoveries. This study collectively suggests that changes in fast transmission through PFC inhibitory microcircuits are a central component of the neurobiological effects of ethanol and the core symptoms of AUDs. Finally, we submit that there is a significant and timely need to examine sex as a biological variable and human postmortem brain tissue to maximize the efforts in translating findings to new clinical treatments.
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Affiliation(s)
| | - Max E. Joffe
- Translational Neuroscience Program, Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, United States
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16
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Parent MB. Using Postmeal Measures and Manipulations to Investigate Hippocampal Mnemonic Control of Eating Behavior. Neuroscience 2022; 497:228-238. [PMID: 34998891 PMCID: PMC9256844 DOI: 10.1016/j.neuroscience.2021.12.040] [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: 09/12/2021] [Revised: 12/27/2021] [Accepted: 12/30/2021] [Indexed: 10/19/2022]
Abstract
Episodic meal-related memories provide the brain with a powerful mechanism for tracking and controlling eating behavior because they contain a detailed record of recent energy intake that likely outlasts the physiological signals generated by feeding bouts. This review briefly summarizes evidence from human participants showing that episodic meal-related memory limits later eating behavior and then describes our research aimed at investigating whether hippocampal neurons mediate the inhibitory effects of meal-related memory on subsequent feeding. Our approach has been inspired by pioneering work conducted by Ivan Izquierdo and others who used posttraining manipulations to investigate memory consolidation. This review describes the rationale and value of posttraining manipulations, how Izquierdo used them to demonstrate that dorsal hippocampal (dHC) neurons are critical for memory consolidation, and how we have adapted this strategy to investigate whether dHC neurons are necessary for mnemonic control of energy intake. I describe our evidence showing that ingestion activates the molecular processes necessary for synaptic plasticity and memory during the early postprandial period, when the memory of the meal would be undergoing consolidation, and then summarize our findings showing that neural activity in dHC neurons is critical during the early postprandial period for limiting future intake. Collectively, our evidence supports the hypothesis that dHC neurons mediate the inhibitory effects of ingestion-related memory on future intake and demonstrates that post-experience memory modulation is not confined to artificial laboratory memory tasks.
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Affiliation(s)
- M B Parent
- Neuroscience Institute & Department of Psychology, Georgia State University, PO Box 5030, Atlanta, GA 30303, USA.
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17
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Sakalar E, Klausberger T, Lasztóczi B. Neurogliaform cells dynamically decouple neuronal synchrony between brain areas. Science 2022; 377:324-328. [DOI: 10.1126/science.abo3355] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Effective communication across brain areas requires distributed neuronal networks to dynamically synchronize or decouple their ongoing activity. GABA
ergic
interneurons lock ensembles to network oscillations, but there remain questions regarding how synchrony is actively disengaged to allow for new communication partners. We recorded the activity of identified interneurons in the CA1 hippocampus of awake mice. Neurogliaform cells (NGFCs)—which provide GABA
ergic
inhibition to distal dendrites of pyramidal cells—strongly coupled their firing to those gamma oscillations synchronizing local networks with cortical inputs. Rather than strengthening such synchrony, action potentials of NGFCs decoupled pyramidal cell activity from cortical gamma oscillations but did not reduce their firing nor affect local oscillations. Thus, NGFCs regulate information transfer by temporarily disengaging the synchrony without decreasing the activity of communicating networks.
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Affiliation(s)
- Ece Sakalar
- Division of Cognitive Neurobiology, Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Thomas Klausberger
- Division of Cognitive Neurobiology, Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Bálint Lasztóczi
- Division of Cognitive Neurobiology, Center for Brain Research, Medical University of Vienna, Vienna, Austria
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18
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Gupta A, Dovek L, Proddutur A, Elgammal FS, Santhakumar V. Long-Term Effects of Moderate Concussive Brain Injury During Adolescence on Synaptic and Tonic GABA Currents in Dentate Granule Cells and Semilunar Granule Cells. Front Neurosci 2022; 16:800733. [PMID: 35360164 PMCID: PMC8964009 DOI: 10.3389/fnins.2022.800733] [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: 10/23/2021] [Accepted: 01/27/2022] [Indexed: 01/27/2023] Open
Abstract
Progressive physiological changes in the hippocampal dentate gyrus circuits following traumatic brain injury (TBI) contribute to temporal evolution of neurological sequelae. Although early posttraumatic changes in dentate synaptic and extrasynaptic GABA currents have been reported, and whether they evolve over time and remain distinct between the two projection neuron classes, granule cells and semilunar granule cells, have not been evaluated. We examined long-term changes in tonic GABA currents and spontaneous inhibitory postsynaptic currents (sIPSCs) and in dentate projection neurons 3 months after moderate concussive fluid percussion injury (FPI) in adolescent rats. Granule cell tonic GABA current amplitude remained elevated up to 1 month after FPI, but decreased to levels comparable with age-matched controls by 3 months postinjury. Granule cell sIPSC frequency, which we previously reported to be increased 1 week after FPI, remained higher than in age-matched controls at 1 month and was significantly reduced 3 months after FPI. In semilunar granule cells, tonic GABA current amplitude and sIPSC frequency were not different from controls 3 months after FPI, which contrast with decreases observed 1 week after injury. The switch in granule cell inhibitory inputs from early increase to subsequent decrease could contribute to the delayed emergence of cognitive deficits and seizure susceptibility after brain injury.
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Affiliation(s)
- Akshay Gupta
- Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, Newark, NJ, United States,Department of Molecular, Cell and Systems Biology, University of California, Riverside, Riverside, CA, United States
| | - Laura Dovek
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, Riverside, CA, United States
| | - Archana Proddutur
- Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, Newark, NJ, United States,Department of Molecular, Cell and Systems Biology, University of California, Riverside, Riverside, CA, United States
| | - Fatima S. Elgammal
- Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, Newark, NJ, United States
| | - Vijayalakshmi Santhakumar
- Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, Newark, NJ, United States,Department of Molecular, Cell and Systems Biology, University of California, Riverside, Riverside, CA, United States,*Correspondence: Vijayalakshmi Santhakumar,
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19
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Lambert PM, Lu X, Zorumski CF, Mennerick S. Physiological markers of rapid antidepressant effects of allopregnanolone. J Neuroendocrinol 2022; 34:e13023. [PMID: 34423498 PMCID: PMC8807818 DOI: 10.1111/jne.13023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Revised: 07/28/2021] [Accepted: 07/29/2021] [Indexed: 02/04/2023]
Abstract
The rise of ketamine and brexanolone as rapid antidepressant treatments raises the question of common mechanisms. Both drugs act without the long onset time of traditional antidepressants such as selective serotonin reuptake inhibitors. The drugs also share the interesting feature of benefit that persists beyond the initial drug lifetime. Here, we briefly review literature on functional changes that may mark the triggering mechanism of rapid antidepressant actions. Because ketamine has a longer history of study as a rapid antidepressant, we use this literature as a template to guide hypotheses about common action. Brexanolone has the complication of being a formulation of a naturally occurring neurosteroid; thus, endogenous levels need to be considered when studying the impact of exogenous administration. We conclude that network disinhibition and increased high-frequency oscillations are candidates to mediate acute triggering effects of rapid antidepressants.
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Affiliation(s)
- Peter M Lambert
- Department of Psychiatry, Washington University in St Louis School of Medicine, St Louis, MO, USA
| | - Xinguo Lu
- Department of Psychiatry, Washington University in St Louis School of Medicine, St Louis, MO, USA
| | - Charles F Zorumski
- Department of Psychiatry, Washington University in St Louis School of Medicine, St Louis, MO, USA
- Taylor Family Institute for Innovative Psychiatric Research, Washington University in St Louis School of Medicine, St Louis, MO, USA
| | - Steven Mennerick
- Department of Psychiatry, Washington University in St Louis School of Medicine, St Louis, MO, USA
- Taylor Family Institute for Innovative Psychiatric Research, Washington University in St Louis School of Medicine, St Louis, MO, USA
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20
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Belelli D, Phillips GD, Atack JR, Lambert JJ. Relating neurosteroid modulation of inhibitory neurotransmission to behaviour. J Neuroendocrinol 2022; 34:e13045. [PMID: 34644812 DOI: 10.1111/jne.13045] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 08/24/2021] [Accepted: 09/15/2021] [Indexed: 12/11/2022]
Abstract
Studies in the 1980s revealed endogenous metabolites of progesterone and deoxycorticosterone to be potent, efficacious, positive allosteric modulators (PAMs) of the GABAA receptor (GABAA R). The discovery that such steroids are locally synthesised in the central nervous system (CNS) promoted the thesis that neural inhibition in the CNS may be "fine-tuned" by these neurosteroids to influence behaviour. In preclinical studies, these neurosteroids exhibited anxiolytic, anticonvulsant, analgesic and sedative properties and, at relatively high doses, induced a state of general anaesthesia, a profile consistent with their interaction with GABAA Rs. However, realising the therapeutic potential of either endogenous neurosteroids or synthetic "neuroactive" steroids has proven challenging. Recent approval by the Food and Drug Administration of the use of allopregnanolone (brexanolone) to treat postpartum depression has rekindled enthusiasm for exploring their potential as new medicines. Although neurosteroids are selective for GABAA Rs, they exhibit little or no selectivity across the many GABAA R subtypes. Nevertheless, a relatively minor population of receptors incorporating the δ-subunit (δ-GABAA Rs) appears to be an important contributor to their behavioural effects. Here, we consider how neurosteroids acting upon GABAA Rs influence neuronal signalling, as well as how such effects may acutely and persistently influence behaviour, and explore the case for developing selective PAMs of δ-GABAA R subtypes for the treatment of psychiatric disorders.
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Affiliation(s)
- Delia Belelli
- Neuroscience, Division of Systems Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee, UK
| | - Grant D Phillips
- Neuroscience, Division of Systems Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee, UK
| | - John R Atack
- Medicines Discovery Institute, Cardiff University, Cardiff, UK
| | - Jeremy J Lambert
- Neuroscience, Division of Systems Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee, UK
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21
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Parent MB, Higgs S, Cheke LG, Kanoski SE. Memory and eating: A bidirectional relationship implicated in obesity. Neurosci Biobehav Rev 2022; 132:110-129. [PMID: 34813827 PMCID: PMC8816841 DOI: 10.1016/j.neubiorev.2021.10.051] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 10/17/2021] [Accepted: 10/28/2021] [Indexed: 01/03/2023]
Abstract
This paper reviews evidence demonstrating a bidirectional relationship between memory and eating in humans and rodents. In humans, amnesia is associated with impaired processing of hunger and satiety cues, disrupted memory of recent meals, and overconsumption. In healthy participants, meal-related memory limits subsequent ingestive behavior and obesity is associated with impaired memory and disturbances in the hippocampus. Evidence from rodents suggests that dorsal hippocampal neural activity contributes to the ability of meal-related memory to control future intake, that endocrine and neuropeptide systems act in the ventral hippocampus to provide cues regarding energy status and regulate learned aspects of eating, and that consumption of hypercaloric diets and obesity disrupt these processes. Collectively, this evidence indicates that diet-induced obesity may be caused and/or maintained, at least in part, by a vicious cycle wherein excess intake disrupts hippocampal functioning, which further increases intake. This perspective may advance our understanding of how the brain controls eating, the neural mechanisms that contribute to eating-related disorders, and identify how to treat diet-induced obesity.
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Affiliation(s)
- Marise B. Parent
- Neuroscience Institute & Department of Psychology, Georgia State University, Box 5030, Atlanta, GA 30303-5030, United States,Corresponding author: Marise B. Parent, , Georgia State University, PO Box 5030, Atlanta, GA 30303-5030, USA. Fax: 404-413-5446
| | - Suzanne Higgs
- School of Psychology, University of Birmingham, Edgbaston, Birmingham, BI5 2TT, United Kingdom
| | - Lucy G. Cheke
- Department of Psychology, University of Cambridge, Downing Street, Cambridge, CB2 3EB United Kingdom
| | - Scott E Kanoski
- Department of Biological Sciences, Human and Evolutionary Biology Section, University of Southern California, Los Angeles, CA, 90089-0371, United States
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22
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Miczek KA, DiLeo A, Newman EL, Akdilek N, Covington HE. Neurobiological Bases of Alcohol Consumption After Social Stress. Curr Top Behav Neurosci 2022; 54:245-281. [PMID: 34964935 PMCID: PMC9698769 DOI: 10.1007/7854_2021_273] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The urge to seek and consume excessive alcohol is intensified by prior experiences with social stress, and this cascade can be modeled under systematically controlled laboratory conditions in rodents and non-human primates. Adaptive coping with intermittent episodes of social defeat stress often transitions to maladaptive responses to traumatic continuous stress, and alcohol consumption may become part of coping responses. At the circuit level, the neural pathways subserving stress coping intersect with those for alcohol consumption. Increasingly discrete regions and connections within the prefrontal cortex, the ventral and dorsal striatum, thalamic and hypothalamic nuclei, tegmental areas as well as brain stem structures begin to be identified as critical for reacting to and coping with social stress while seeking and consuming alcohol. Several candidate molecules that modulate signals within these neural connections have been targeted in order to reduce excessive drinking and relapse. In spite of some early clinical failures, neuropeptides such as CRF, opioids, or oxytocin continue to be examined for their role in attenuating stress-escalated drinking. Recent work has focused on neural sites of action for peptides and steroids, most likely in neuroinflammatory processes as a result of interactive effects of episodic social stress and excessive alcohol seeking and drinking.
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Affiliation(s)
- Klaus A. Miczek
- Department of Psychology, Tufts University, Medford, MA, USA,Department of Neuroscience, Tufts University, Boston, MA, USA
| | - Alyssa DiLeo
- Department of Neuroscience, Tufts University, Boston, MA, USA
| | - Emily L. Newman
- Department of Psychiatry, Harvard Medical School, Belmont, MA, USA
| | - Naz Akdilek
- Department of Psychology, Tufts University, Medford, MA, USA
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23
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Shu HJ, Lu X, Bracamontes J, Steinbach JH, Zorumski CF, Mennerick S. Pharmacological and Biophysical Characteristics of Picrotoxin-Resistant, δSubunit-Containing GABA A Receptors. Front Synaptic Neurosci 2021; 13:763411. [PMID: 34867260 PMCID: PMC8636460 DOI: 10.3389/fnsyn.2021.763411] [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: 08/23/2021] [Accepted: 10/26/2021] [Indexed: 11/21/2022] Open
Abstract
GABAA receptors (GABAARs) play a crucial role in inhibition in the central nervous system. GABAARs containing the δ subunit mediate tonic inhibition, have distinctive pharmacological properties and are associated with disorders of the nervous system. To explore this receptor sub-class, we recently developed mice with δ-containing receptors rendered resistant to the common non-competitive antagonist picrotoxin (PTX). Resistance was achieved with a knock-in point mutation (T269Y; T6’Y) in the mouse genome. Here we characterize pharmacological and biophysical features of GABAARs containing the mutated subunit to contextualize results from the KI mice. Recombinant receptors containing δ T6’Y plus WT α4 and WT β2 subunits exhibited 3-fold lower EC50 values for GABA but not THIP. GABA EC50 values in native receptors containing the mutated subunit were in the low micromolar range, in contrast with some published results that have suggested nM sensitivity of recombinant receptors. Rectification properties of δ-containing GABAARs were similar to γ2-containing receptors. Receptors containing δ T6’Y had marginally weaker sensitivity to positive allosteric modulators, likely a secondary consequence of differing GABA sensitivity. Overexpression of δT6’Y in neurons resulted in robust PTX-insensitive IPSCs, suggesting that δ-containing receptors are readily recruited by synaptically released GABA. Overall, our results give context to the use of δ receptors with the T6’Y mutation to explore the roles of δ-containing receptors in inhibition.
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Affiliation(s)
- Hong-Jin Shu
- Department of Psychiatry, Washington University in St. Louis, School of Medicine, St. Louis, MO, United States
| | - Xinguo Lu
- Department of Psychiatry, Washington University in St. Louis, School of Medicine, St. Louis, MO, United States
| | - John Bracamontes
- Department of Anesthesiology, Washington University in St. Louis, School of Medicine, St. Louis, MO, United States
| | - Joe Henry Steinbach
- Department of Anesthesiology, Washington University in St. Louis, School of Medicine, St. Louis, MO, United States.,Taylor Family Institute for Innovative Psychiatric Research, Washington University in St. Louis, School of Medicine, St. Louis, MO, United States
| | - Charles F Zorumski
- Department of Psychiatry, Washington University in St. Louis, School of Medicine, St. Louis, MO, United States.,Taylor Family Institute for Innovative Psychiatric Research, Washington University in St. Louis, School of Medicine, St. Louis, MO, United States.,Department of Neuroscience, Washington University in St. Louis, School of Medicine, St. Louis, MO, United States
| | - Steven Mennerick
- Department of Psychiatry, Washington University in St. Louis, School of Medicine, St. Louis, MO, United States.,Taylor Family Institute for Innovative Psychiatric Research, Washington University in St. Louis, School of Medicine, St. Louis, MO, United States.,Department of Neuroscience, Washington University in St. Louis, School of Medicine, St. Louis, MO, United States
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24
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Tonic GABA A Receptor-Mediated Currents of Human Cortical GABAergic Interneurons Vary Amongst Cell Types. J Neurosci 2021; 41:9702-9719. [PMID: 34667071 PMCID: PMC8612645 DOI: 10.1523/jneurosci.0175-21.2021] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 09/08/2021] [Accepted: 09/10/2021] [Indexed: 12/03/2022] Open
Abstract
Persistent anion conductances through GABAA receptors (GABAARs) are important modulators of neuronal excitability. However, it is currently unknown how the amplitudes of these currents vary among different cell types in the human neocortex, particularly among diverse GABAergic interneurons. We have recorded 101 interneurons in and near layer 1 from cortical tissue surgically resected from both male and female patients, visualized 84 of them and measured tonic GABAAR currents in 48 cells with an intracellular [Cl–] of 65 mm and in the presence of 5 μm GABA. We compare these tonic currents among five groups of interneurons divided by firing properties and four types of interneuron defined by axonal distributions; rosehip, neurogliaform, stalked-bouton, layer 2–3 innervating and a pool of other cells. Interestingly, the rosehip cell, a type of interneuron only described thus far in human tissue, and layer 2–3 innervating cells exhibit larger tonic currents than other layer 1 interneurons, such as neurogliaform and stalked-bouton cells; the latter two groups showing no difference. The positive allosteric modulators of GABAARs allopregnanolone and DS2 also induced larger current shifts in the rosehip and layer 2–3 innervating cells, consistent with higher expression of the δ subunit of the GABAAR in these neurons. We have also examined how patient parameters, such as age, seizures, type of cancer and anticonvulsant treatment may alter tonic inhibitory currents in human neurons. The cell type-specific differences in tonic inhibitory currents could potentially be used to selectively modulate cortical circuitry. SIGNIFICANCE STATEMENT Tonic currents through GABAA receptors (GABAARs) are a potential therapeutic target for a number of neurologic and psychiatric conditions. Here, we show that these currents in human cerebral cortical GABAergic neurons display cell type-specific differences in their amplitudes which implies differential modulation of their excitability. Additionally, we examine whether the amplitudes of the tonic currents measured in our study show any differences between patient populations, finding some evidence that age, seizures, type of cancer, and anticonvulsant treatment may alter tonic inhibition in human tissue. These results advance our understanding of how pathology affects neuronal excitability and could potentially be used to selectively modulate cortical circuitry.
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Belelli D, Hales TG, Lambert JJ, Luscher B, Olsen R, Peters JA, Rudolph U, Sieghart W. GABA A receptors in GtoPdb v.2021.3. IUPHAR/BPS GUIDE TO PHARMACOLOGY CITE 2021; 2021. [PMID: 35005623 DOI: 10.2218/gtopdb/f72/2021.3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The GABAA receptor is a ligand-gated ion channel of the Cys-loop family that includes the nicotinic acetylcholine, 5-HT3 and strychnine-sensitive glycine receptors. GABAA receptor-mediated inhibition within the CNS occurs by fast synaptic transmission, sustained tonic inhibition and temporally intermediate events that have been termed 'GABAA, slow' [45]. GABAA receptors exist as pentamers of 4TM subunits that form an intrinsic anion selective channel. Sequences of six α, three β, three γ, one δ, three ρ, one ε, one π and one θ GABAA receptor subunits have been reported in mammals [278, 235, 236, 283]. The π-subunit is restricted to reproductive tissue. Alternatively spliced versions of many subunits exist (e.g. α4- and α6- (both not functional) α5-, β2-, β3- and γ2), along with RNA editing of the α3 subunit [71]. The three ρ-subunits, (ρ1-3) function as either homo- or hetero-oligomeric assemblies [359, 50]. Receptors formed from ρ-subunits, because of their distinctive pharmacology that includes insensitivity to bicuculline, benzodiazepines and barbiturates, have sometimes been termed GABAC receptors [359], but they are classified as GABA A receptors by NC-IUPHAR on the basis of structural and functional criteria [16, 235, 236]. Many GABAA receptor subtypes contain α-, β- and γ-subunits with the likely stoichiometry 2α.2β.1γ [168, 235]. It is thought that the majority of GABAA receptors harbour a single type of α- and β - subunit variant. The α1β2γ2 hetero-oligomer constitutes the largest population of GABAA receptors in the CNS, followed by the α2β3γ2 and α3β3γ2 isoforms. Receptors that incorporate the α4- α5-or α 6-subunit, or the β1-, γ1-, γ3-, δ-, ε- and θ-subunits, are less numerous, but they may nonetheless serve important functions. For example, extrasynaptically located receptors that contain α6- and δ-subunits in cerebellar granule cells, or an α4- and δ-subunit in dentate gyrus granule cells and thalamic neurones, mediate a tonic current that is important for neuronal excitability in response to ambient concentrations of GABA [209, 272, 83, 19, 288]. GABA binding occurs at the β+/α- subunit interface and the homologous γ+/α- subunits interface creates the benzodiazepine site. A second site for benzodiazepine binding has recently been postulated to occur at the α+/β- interface ([254]; reviewed by [282]). The particular α-and γ-subunit isoforms exhibit marked effects on recognition and/or efficacy at the benzodiazepine site. Thus, receptors incorporating either α4- or α6-subunits are not recognised by 'classical' benzodiazepines, such as flunitrazepam (but see [356]). The trafficking, cell surface expression, internalisation and function of GABAA receptors and their subunits are discussed in detail in several recent reviews [52, 140, 188, 316] but one point worthy of note is that receptors incorporating the γ2 subunit (except when associated with α5) cluster at the postsynaptic membrane (but may distribute dynamically between synaptic and extrasynaptic locations), whereas as those incorporating the δ subunit appear to be exclusively extrasynaptic. NC-IUPHAR [16, 235, 3, 2] class the GABAA receptors according to their subunit structure, pharmacology and receptor function. Currently, eleven native GABAA receptors are classed as conclusively identified (i.e., α1β2γ2, α1βγ2, α3βγ2, α4βγ2, α4β2δ, α4β3δ, α5βγ2, α6βγ2, α6β2δ, α6β3δ and ρ) with further receptor isoforms occurring with high probability, or only tentatively [235, 236]. It is beyond the scope of this Guide to discuss the pharmacology of individual GABAA receptor isoforms in detail; such information can be gleaned in the reviews [16, 95, 168, 173, 143, 278, 216, 235, 236] and [9, 10]. Agents that discriminate between α-subunit isoforms are noted in the table and additional agents that demonstrate selectivity between receptor isoforms, for example via β-subunit selectivity, are indicated in the text below. The distinctive agonist and antagonist pharmacology of ρ receptors is summarised in the table and additional aspects are reviewed in [359, 50, 145, 223]. Several high-resolution cryo-electron microscopy structures have been described in which the full-length human α1β3γ2L GABAA receptor in lipid nanodiscs is bound to the channel-blocker picrotoxin, the competitive antagonist bicuculline, the agonist GABA (γ-aminobutyric acid), and the classical benzodiazepines alprazolam and diazepam [198].
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Liao VWY, Chebib M, Ahring PK. Efficient expression of concatenated α1β2δ and α1β3δ GABA A receptors, their pharmacology and stoichiometry. Br J Pharmacol 2021; 178:1556-1573. [PMID: 33491192 DOI: 10.1111/bph.15380] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 12/28/2020] [Accepted: 01/11/2021] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND AND PURPOSE GABAA receptors containing δ-subunits are notorious for being difficult to study in vitro due to heterogeneity of expressed receptor populations and low GABA-evoked current amplitudes. Thus, there are some published misconceptions and contradictory conclusions made regarding the pharmacology and stoichiometry of δ-containing receptors. The aim of this study was to obtain robust homogenous expression of α1βδ receptors for in-depth investigation. EXPERIMENTAL APPROACH Novel δ-containing pentameric concatenated constructs were designed. The resulting α1β2δ and α1β3δ GABAA receptor concatemers were investigated by two-electrode voltage-clamp electrophysiology using Xenopus laevis oocytes. KEY RESULTS First, while homogenous α1βδ GABAA receptor pools could not be obtained by manipulating the ratio of injected cRNAs of free α1, β2/3, and δ subunits, concatenated pentameric α1β2δ and α1β3δ constructs resulted in robust expression levels of concatemers. Second, by using optimised constructs that give unidirectional assembly of concatemers, we found that the δ subunit cannot directly participate in GABA binding and receptor activation. Hence, functional δ-containing receptors are likely to all have a conventional 2α:2β:1δ stoichiometry arranged as βαβαδ when viewed counterclockwise from the extracellular side. Third, α1β2/3δ receptors were found to express efficiently in X. laevis oocytes but have a low estimated open probability of ~0.5% upon GABA activation. Because of this, these receptors are uniquely susceptible to positive allosteric modulation by, for example, neurosteroids. CONCLUSION AND IMPLICATIONS Our data answer important outstanding questions regarding the pharmacology and stoichiometry of α1δ-containing GABAA receptors and pave the way for future analysis and drug discovery efforts.
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Affiliation(s)
- Vivian Wan Yu Liao
- Brain and Mind Centre, Sydney Pharmacy School, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
| | - Mary Chebib
- Brain and Mind Centre, Sydney Pharmacy School, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
| | - Philip Kiaer Ahring
- Brain and Mind Centre, Sydney Pharmacy School, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
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Niu G, Deng L, Zhang X, Hu Z, Han S, Xu K, Hong R, Meng H, Ke C. GABRD promotes progression and predicts poor prognosis in colorectal cancer. Open Med (Wars) 2020; 15:1172-1183. [PMID: 33336074 PMCID: PMC7718617 DOI: 10.1515/med-2020-0128] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Revised: 07/22/2020] [Accepted: 08/13/2020] [Indexed: 02/07/2023] Open
Abstract
Little is known about the functional roles of gamma-aminobutyric acid type A receptor subunit delta (GABRD) in colorectal cancer (CRC). The expression of GABRD between CRCs and adjacent normal tissues (NTs), metastasis and primary tumors was compared using public transcriptomic datasets. A tissue microarray and immunohistochemical staining (IHC) were used to determine the clinical and prognostic significance of the GABRD in CRC. We used gain-of-function and loss-of-function experiments to investigate the in vitro roles of GABRD in cultured CRC cells. We characterized the potential mechanism of GABRD’s activities in CRC using a Gene Set Enrichment Analysis (GSEA) with The Cancer Genome Atlas Colon Adenocarcinoma (TCGA-COAD) dataset. We found that the GABRD expression was significantly increased in CRCs compared to that in NTs, but was similar between metastasis and primary tumors. Overexpression of GABRD was significantly associated with later pTNM stages and unfavorable patient survival. Overexpression of GABRD accelerated while knock-down of GABRD inhibited cell growth and migration. Mechanistically, the function of GABRD might be ascribed to its influence on major oncogenic events such as epithelial–mesenchymal transition (EMT), angiogenesis, and hedgehog signaling. Collectively, GABRD could be a novel prognostic predictor for CRC that deserves further investigation.
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Affiliation(s)
- Gengming Niu
- Department of General Surgery, the Fifth People's Hospital of Shanghai, Fudan University, 801 Heqing Road, Shanghai, 200240, People's Republic of China
| | - Li Deng
- Department of General Surgery, the Fifth People's Hospital of Shanghai, Fudan University, 801 Heqing Road, Shanghai, 200240, People's Republic of China
| | - Xiaotian Zhang
- Department of General Surgery, the Fifth People's Hospital of Shanghai, Fudan University, 801 Heqing Road, Shanghai, 200240, People's Republic of China
| | - Zhiqing Hu
- Department of General Surgery, the Fifth People's Hospital of Shanghai, Fudan University, 801 Heqing Road, Shanghai, 200240, People's Republic of China
| | - Shanliang Han
- Department of General Surgery, the Fifth People's Hospital of Shanghai, Fudan University, 801 Heqing Road, Shanghai, 200240, People's Republic of China
| | - Ke Xu
- Department of Animal Science, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China
| | - Runqi Hong
- Department of General Surgery, the Fifth People's Hospital of Shanghai, Fudan University, 801 Heqing Road, Shanghai, 200240, People's Republic of China
| | - He Meng
- Department of Animal Science, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China
| | - Chongwei Ke
- Department of General Surgery, the Fifth People's Hospital of Shanghai, Fudan University, 801 Heqing Road, Shanghai, 200240, People's Republic of China
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Venuti LS, Pena-Flores NL, Herberholz J. Cellular interactions between social experience, alcohol sensitivity, and GABAergic inhibition in a crayfish neural circuit. J Neurophysiol 2020; 125:256-272. [PMID: 33174493 DOI: 10.1152/jn.00519.2020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
We report here that prior social experience modified the behavioral responses of adult crayfish to acute alcohol exposure. Animals housed individually for 1 wk before alcohol exposure were less sensitive to the intoxicating effects of alcohol than animals housed in groups, and these differences are based on changes in the nervous system rather than differences in alcohol uptake. To elucidate the underlying neural mechanisms, we investigated the neurophysiological responses of the lateral giant (LG) interneurons after alcohol exposure. Specifically, we measured the interactions between alcohol and different GABAA-receptor antagonists and agonists in reduced crayfish preparations devoid of brain-derived tonic GABAergic inhibition. We found that alcohol significantly increased the postsynaptic potential of the LG neurons, but contrary to our behavioral observations, the results were similar for isolated and communal animals. The GABAA-receptor antagonist picrotoxin, however, facilitated LG postsynaptic potentials more strongly in communal crayfish, which altered the neurocellular interactions with alcohol, whereas TPMPA [(1,2,5,6-tetrahydropyridin-4-yl)methylphosphinic acid], an antagonist directed against GABAA-receptors with ρ subunits, did not produce any effects. Muscimol, an agonist for GABAA-receptors, blocked the stimulating effects of alcohol, but this was independent of prior social history. THIP [4,5,6,7-tetrahydroisoxazolo(5,4-c)pyridin-3-ol], an agonist directed against GABAA-receptors with δ subunits, which were not previously known to exist in the LG circuit, replicated the suppressing effects of muscimol. Together, our findings provide strong evidence that alcohol interacts with the crayfish GABAergic system, and the interplay between prior social experience and acute alcohol intoxication might be linked to changes in the expression and function of specific GABAA-receptor subtypes.NEW & NOTEWORTHY The complex interactions between alcohol and prior social experience are still poorly understood. Our work demonstrates that socially isolated crayfish exhibit lower neurobehavioral sensitivity to acute ethanol compared with communally housed animals, and this socially mediated effect is based on changes in the nervous systems rather than on differences in uptake or metabolism. By combining intracellular neurophysiology and neuropharmacology, we investigated the role of the main inhibitory neurotransmitter GABA, and its receptor subtypes, in shaping this process.
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Affiliation(s)
| | | | - Jens Herberholz
- Neuroscience and Cognitive Science Program.,Department of Psychology, University of Maryland, College Park, Maryland
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Luhmann HJ, Fukuda A. Can we understand human brain development from experimental studies in rodents? Pediatr Int 2020; 62:1139-1144. [PMID: 32531857 DOI: 10.1111/ped.14339] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 05/05/2020] [Accepted: 05/22/2020] [Indexed: 12/12/2022]
Abstract
Animal models are needed to gain an understanding of the genetic, molecular, cellular, and network mechanisms of human brain development. In rodents, a large spectrum of in vitro and in vivo approaches allows detailed analyses and specific experimental manipulations for studying the sequence of developmental steps in corticogenesis. Neurogenesis, neuronal migration, cellular differentiation, programmed cell death, synaptogenesis, and myelination are surprisingly similar in the rodent cortex and the human cortex. Spontaneous EEG activity in the pre- and early postnatal human cortex resembles the activity patterns recorded with intracortical multi-electrode arrays in newborn rodents. This early activity is generated by thalamic activation of a subplate-driven local network coupled via gap junctions, which controls the development of cortical columns and the spatio-temporal pattern of apoptosis. Disturbances of this activity may induce disturbances in cortical structure and function leading to neurological and psychiatric disorders.
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Affiliation(s)
- Heiko J Luhmann
- Institute of Physiology, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Atsuo Fukuda
- Department of Physiology, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
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Shen H, Kenney L, Smith SS. Increased Dendritic Branching of and Reduced δ-GABA A Receptor Expression on Parvalbumin-Positive Interneurons Increase Inhibitory Currents and Reduce Synaptic Plasticity at Puberty in Female Mouse CA1 Hippocampus. Front Cell Neurosci 2020; 14:203. [PMID: 32733208 PMCID: PMC7363981 DOI: 10.3389/fncel.2020.00203] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 06/10/2020] [Indexed: 12/04/2022] Open
Abstract
Parvalbumin positive (PV+) interneurons play a pivotal role in cognition and are known to be regulated developmentally and by ovarian hormones. The onset of puberty represents the end of a period of optimal learning when impairments in synaptic plasticity are observed in the CA1 hippocampus of female mice. Therefore, we tested whether the synaptic inhibitory current generated by PV+ interneurons is increased at puberty and contributes to these deficits in synaptic plasticity. To this end, the spontaneous inhibitory postsynaptic current (sIPSC) was recorded using whole-cell patch-clamp techniques from CA1 pyramidal cells in the hippocampal slice before (PND 28–32) and after the onset of puberty in female mice (~PND 35–44, assessed by vaginal opening). sIPSC frequency and amplitude were significantly increased at puberty, but these measures were reduced by 1 μM DAMGO [1 μM, (D-Ala2, N-MePhe4, Gly-ol)-enkephalin], which silences PV+ activity via μ-opioid receptor targets. At puberty, dendritic branching of PV+ interneurons in GAD67-GFP mice was increased, while expression of the δ subunit of the GABAA receptor (GABAR) on these interneurons decreased. Both frequency and amplitude of sIPSCs were significantly increased in pre-pubertal mice with reduced δ expression, suggesting a possible mechanism. Theta burst induction of long-term potentiation (LTP), an in vitro model of learning, is impaired at puberty but was restored to optimal levels by DAMGO administration, implicating inhibition via PV+ interneurons as one cause. Administration of the neurosteroid/stress steroid THP (30 nM, 3α-OH, 5α-pregnan-20-one) had no effect on sIPSCs. These findings suggest that phasic inhibition generated by PV+ interneurons is increased at puberty when it contributes to impairments in synaptic plasticity. These results may have relevance for the changes in cognitive function reported during early adolescence.
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Affiliation(s)
- Hui Shen
- Department of Physiology and Pharmacology, SUNY Downstate Medical Center, Brooklyn, NY, United States.,Research Institute of Neurology, General Hospital, Tianjin Medical University, Heping District, Tianjin, China
| | - Lindsay Kenney
- Department of Physiology and Pharmacology, SUNY Downstate Medical Center, Brooklyn, NY, United States.,Program in Neural and Behavioral Science, SUNY Downstate Medical Center, Brooklyn, NY, United States
| | - Sheryl S Smith
- Department of Physiology and Pharmacology, SUNY Downstate Medical Center, Brooklyn, NY, United States.,The Robert F. Furchgott Center for Neural and Behavioral Science, SUNY Downstate Medical Center, Brooklyn, NY, United States
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31
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Falk-Petersen CB, Tsonkov TM, Nielsen MS, Harpsøe K, Bundgaard C, Frølund B, Kristiansen U, Gloriam DE, Wellendorph P. Discovery of a new class of orthosteric antagonists with nanomolar potency at extrasynaptic GABA A receptors. Sci Rep 2020; 10:10078. [PMID: 32572053 PMCID: PMC7308271 DOI: 10.1038/s41598-020-66821-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 05/20/2020] [Indexed: 02/06/2023] Open
Abstract
Brain GABAΑ receptors are ionotropic receptors belonging to the class of Cys-loop receptors and are important drug targets for the treatment of anxiety and sleep disorders. By screening a compound library (2,112 compounds) at recombinant human α4β1δ GABAΑ receptors heterologously expressed in a HEK cell line, we identified a scaffold of spirocyclic compounds with nanomolar antagonist activity at GABAΑ receptors. The initial screening hit 2027 (IC50 of 1.03 μM) was used for analogue search resulting in 018 (IC50 of 0.088 μM). 018 was most potent at α3,4,5-subunit containing receptors, thus showing preference for forebrain-expressed extrasynaptic receptors. Schild analysis of 018 at recombinant human α4β1δ receptors and displacement of [3H]muscimol binding in rat cortical homogenate independently confirmed a competitive profile. The antagonist profile of 018 was further validated by whole-cell patch-clamp electrophysiology, where kinetic studies revealed a slow dissociation rate and a shallow hill slope was observed. Membrane permeability studies showed that 2027 and 018 do not cross membranes, thus making the compounds less attractive for studying central GABAΑ receptors effects, but conversely more attractive as tool compounds in relation to emerging peripheral GABAΑ receptor-mediated effects of GABA e.g. in the immune system.
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Affiliation(s)
- Christina Birkedahl Falk-Petersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen Ø, Denmark
| | - Tsonko M Tsonkov
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen Ø, Denmark
| | - Malene Sofie Nielsen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen Ø, Denmark
| | - Kasper Harpsøe
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen Ø, Denmark
| | | | - Bente Frølund
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen Ø, Denmark
| | - Uffe Kristiansen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen Ø, Denmark
| | - David E Gloriam
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen Ø, Denmark
| | - Petrine Wellendorph
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen Ø, Denmark.
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Neonatal Clonazepam Administration Induced Long-Lasting Changes in GABA A and GABA B Receptors. Int J Mol Sci 2020; 21:ijms21093184. [PMID: 32366006 PMCID: PMC7246485 DOI: 10.3390/ijms21093184] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 04/24/2020] [Accepted: 04/28/2020] [Indexed: 11/17/2022] Open
Abstract
Benzodiazepines (BZDs) are widely used in patients of all ages. Unlike adults, neonatal animals treated with BZDs exhibit a variety of behavioral deficits later in life; however, the mechanisms underlying these deficits are poorly understood. This study aims to examine whether administration of clonazepam (CZP; 1 mg/kg/day) in 7-11-day-old rats affects Gama aminobutyric acid (GABA)ergic receptors in both the short and long terms. Using RT-PCR and quantitative autoradiography, we examined the expression of the selected GABAA receptor subunits (α1, α2, α4, γ2, and δ) and the GABAB B2 subunit, and GABAA, benzodiazepine, and GABAB receptor binding 48 h, 1 week, and 2 months after treatment discontinuation. Within one week after CZP cessation, the expression of the α2 subunit was upregulated, whereas that of the δ subunit was downregulated in both the hippocampus and cortex. In the hippocampus, the α4 subunit was downregulated after the 2-month interval. Changes in receptor binding were highly dependent on the receptor type, the interval after treatment cessation, and the brain structure. GABAA receptor binding was increased in almost all of the brain structures after the 48-h interval. BZD-binding was decreased in many brain structures involved in the neuronal networks associated with emotional behavior, anxiety, and cognitive functions after the 2-month interval. Binding of the GABAB receptors changed depending on the interval and brain structure. Overall, the described changes may affect both synaptic development and functioning and may potentially cause behavioral impairment.
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Kreuzer M, García PS, Brucklacher-Waldert V, Claassen R, Schneider G, Antkowiak B, Drexler B. Diazepam and ethanol differently modulate neuronal activity in organotypic cortical cultures. BMC Neurosci 2019; 20:58. [PMID: 31823754 PMCID: PMC6902402 DOI: 10.1186/s12868-019-0540-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 11/24/2019] [Indexed: 12/17/2022] Open
Abstract
Background The pharmacodynamic results of diazepam and ethanol administration are similar, in that each can mediate amnestic and sedative-hypnotic effects. Although each of these molecules effectively reduce the activity of central neurons, diazepam does so through modulation of a more specific set of receptor targets (GABAA receptors containing a γ-subunit), while alcohol is less selective in its receptor bioactivity. Our investigation focuses on divergent actions of diazepam and ethanol on the firing patterns of cultured cortical neurons. Method We used electrophysiological recordings from organotypic slice cultures derived from Sprague–Dawley rat neocortex. We exposed these cultures to either diazepam (15 and 30 µM, n = 7) or ethanol (30 and 60 mM, n = 11) and recorded the electrical activity at baseline and experimental conditions. For analysis, we extracted the episodes of spontaneous activity, i.e., cortical up-states. After separation of action potential and local field potential (LFP) activity, we looked at differences in the number of action potentials, in the spectral power of the LFP, as well as in the coupling between action potential and LFP phase. Results While both substances seem to decrease neocortical action potential firing in a not significantly different (p = 0.659, Mann–Whitney U) fashion, diazepam increases the spectral power of the up-state without significantly impacting the spectral composition, whereas ethanol does not significantly change the spectral power but the oscillatory architecture of the up-state as revealed by the Friedman test with Bonferroni correction (p < 0.05). Further, the action potential to LFP-phase coupling reveals a synchronizing effect of diazepam for a wide frequency range and a narrow-band de-synchronizing effect for ethanol (p < 0.05, Kolmogorov–Smirnov test). Conclusion Diazepam and ethanol, induce specific patterns of network depressant actions. Diazepam induces cortical network inhibition and increased synchronicity via gamma subunit containing GABAA receptors. Ethanol also induces cortical network inhibition, but without an increase in synchronicity via a wider span of molecular targets.
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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, Germany
| | - Paul S García
- Department of Anesthesiology, Neuroanesthesia Division, Columbia University Medical Center, New York Presbyterian Hospital, New York, USA
| | - Verena Brucklacher-Waldert
- Dept. of Anesthesiology and Intensive Care, Experimental Anesthesiology Section, University Hospital Tübingen, Tübingen, Germany.,Horizon Discovery, 8100 Cambridge Research Park, Waterbeach, Cambridge, CB25 9TL, UK
| | - Rebecca Claassen
- Dept. of Anesthesiology and Intensive Care, Experimental Anesthesiology Section, University Hospital Tübingen, Tübingen, Germany.,Psychiatrie-Zentrum Linthgebiet, Standort Rapperswil, Untere Bahnhofstrasse 11, 8640, Rapperswil, Switzerland
| | - Gerhard Schneider
- Department of Anesthesiology and Intensive Care, Klinikum rechts der Isar, Technical University of Munich, School of Medicine, Munich, Germany
| | - Bernd Antkowiak
- Dept. of Anesthesiology and Intensive Care, Experimental Anesthesiology Section, University Hospital Tübingen, Tübingen, Germany.,Werner Reichardt Center for Integrative Neuroscience, Tübingen, Germany
| | - Berthold Drexler
- Dept. of Anesthesiology and Intensive Care, Experimental Anesthesiology Section, University Hospital Tübingen, Tübingen, Germany.
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Bernstein HL, Lu YL, Botterill JJ, Scharfman HE. Novelty and Novel Objects Increase c-Fos Immunoreactivity in Mossy Cells in the Mouse Dentate Gyrus. Neural Plast 2019; 2019:1815371. [PMID: 31534449 PMCID: PMC6732597 DOI: 10.1155/2019/1815371] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 07/05/2019] [Indexed: 02/06/2023] Open
Abstract
The dentate gyrus (DG) and its primary cell type, the granule cell (GC), are thought to be critical to many cognitive functions. A major neuronal subtype of the DG is the hilar mossy cell (MC). MCs have been considered to play an important role in cognition, but in vivo studies to understand the activity of MCs during cognitive tasks are challenging because the experiments usually involve trauma to the overlying hippocampus or DG, which kills hilar neurons. In addition, restraint typically occurs, and MC activity is reduced by brief restraint stress. Social isolation often occurs and is potentially confounding. Therefore, we used c-fos protein expression to understand when MCs are active in vivo in socially housed adult C57BL/6 mice in their home cage. We focused on c-fos protein expression after animals explored novel objects, based on previous work which showed that MCs express c-fos protein readily in response to a novel housing location. Also, MCs are required for the training component of the novel object location task and novelty-encoding during a food-related task. GluR2/3 was used as a marker of MCs. The results showed that MC c-fos protein is greatly increased after exposure to novel objects, especially in ventral DG. We also found that novel objects produced higher c-fos levels than familiar objects. Interestingly, a small subset of neurons that did not express GluR2/3 also increased c-fos protein after novel object exposure. In contrast, GCs appeared relatively insensitive. The results support a growing appreciation of the role of the DG in novelty detection and novel object recognition, where hilar neurons and especially MCs are very sensitive.
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Affiliation(s)
- Hannah L. Bernstein
- The Nathan S. Kline Institute for Psychiatric Research, Center for Dementia Research, 140 Old Orangeburg Rd., Orangeburg, NY 10962, USA
- Departments of Child and Adolescent Psychiatry, Neuroscience and Physiology, and Psychiatry, and the Neuroscience Institute, New York University Langone Health, 100 First Ave., New York, NY 10016, USA
| | - Yi-Ling Lu
- The Nathan S. Kline Institute for Psychiatric Research, Center for Dementia Research, 140 Old Orangeburg Rd., Orangeburg, NY 10962, USA
- Departments of Child and Adolescent Psychiatry, Neuroscience and Physiology, and Psychiatry, and the Neuroscience Institute, New York University Langone Health, 100 First Ave., New York, NY 10016, USA
| | - Justin J. Botterill
- The Nathan S. Kline Institute for Psychiatric Research, Center for Dementia Research, 140 Old Orangeburg Rd., Orangeburg, NY 10962, USA
- Departments of Child and Adolescent Psychiatry, Neuroscience and Physiology, and Psychiatry, and the Neuroscience Institute, New York University Langone Health, 100 First Ave., New York, NY 10016, USA
| | - Helen E. Scharfman
- The Nathan S. Kline Institute for Psychiatric Research, Center for Dementia Research, 140 Old Orangeburg Rd., Orangeburg, NY 10962, USA
- Departments of Child and Adolescent Psychiatry, Neuroscience and Physiology, and Psychiatry, and the Neuroscience Institute, New York University Langone Health, 100 First Ave., New York, NY 10016, USA
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Trent S, Hall J, Connelly WM, Errington AC. Cyfip1 Haploinsufficiency Does Not Alter GABA A Receptor δ-Subunit Expression and Tonic Inhibition in Dentate Gyrus PV + Interneurons and Granule Cells. eNeuro 2019; 6:ENEURO.0364-18.2019. [PMID: 31209152 PMCID: PMC6635810 DOI: 10.1523/eneuro.0364-18.2019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 05/28/2019] [Accepted: 05/31/2019] [Indexed: 12/01/2022] Open
Abstract
Copy number variation (CNV) at chromosomal region 15q11.2 is linked to increased risk of neurodevelopmental disorders including autism and schizophrenia. A significant gene at this locus is cytoplasmic fragile X mental retardation protein (FMRP) interacting protein 1 (CYFIP1). CYFIP1 protein interacts with FMRP, whose monogenic absence causes fragile X syndrome (FXS). Fmrp knock-out has been shown to reduce tonic GABAergic inhibition by interacting with the δ-subunit of the GABAA receptor (GABAAR). Using in situ hybridization (ISH), qPCR, Western blotting techniques, and patch clamp electrophysiology in brain slices from a Cyfip1 haploinsufficient mouse, we examined δ-subunit mediated tonic inhibition in the dentate gyrus (DG). In wild-type (WT) mice, DG granule cells (DGGCs) responded to the δ-subunit-selective agonist THIP with significantly increased tonic currents. In heterozygous mice, no significant difference was observed in THIP-evoked currents in DGGCs. Phasic GABAergic inhibition in DGGC was also unaltered with no difference in properties of spontaneous IPSCs (sIPSCs). Additionally, we demonstrate that DG granule cell layer (GCL) parvalbumin-positive interneurons (PV+-INs) have functional δ-subunit-mediated tonic GABAergic currents which, unlike DGGC, are also modulated by the α1-selective drug zolpidem. Similar to DGGC, both IPSCs and THIP-evoked currents in PV+-INs were not different between Cyfip1 heterozygous and WT mice. Supporting our electrophysiological data, we found no significant change in hippocampal δ-subunit mRNA expression or protein level and no change in α1/α4-subunit mRNA expression. Thus, Cyfip1 haploinsufficiency, mimicking human 15q11.2 microdeletion syndrome, does not alter hippocampal phasic or tonic GABAergic inhibition, substantially differing from the Fmrp knock-out mouse model.
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Affiliation(s)
- Simon Trent
- Neuroscience and Mental Health Research Institute, School of Medicine, Cardiff University, Cardiff, CF24 4HQ, United Kingdom
| | - Jeremy Hall
- Neuroscience and Mental Health Research Institute, School of Medicine, Cardiff University, Cardiff, CF24 4HQ, United Kingdom
| | - William M Connelly
- School of Medicine, University of Tasmania, Hobart, Tasmania 7000, Australia
| | - Adam C Errington
- Neuroscience and Mental Health Research Institute, School of Medicine, Cardiff University, Cardiff, CF24 4HQ, United Kingdom
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Darnieder LM, Melón LC, Do T, Walton NL, Miczek KA, Maguire JL. Female-specific decreases in alcohol binge-like drinking resulting from GABA A receptor delta-subunit knockdown in the VTA. Sci Rep 2019; 9:8102. [PMID: 31147611 PMCID: PMC6542821 DOI: 10.1038/s41598-019-44286-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 05/08/2019] [Indexed: 02/07/2023] Open
Abstract
Binge drinking is short-term drinking that achieves blood alcohol levels of 0.08 g/dl or above. It exhibits well-established sex differences in GABAergic inhibitory neurotransmission, including extrasynaptic δ subunit-containing GABAA receptors (δ-GABAARs) that mediate tonic inhibition, or synaptic γ2-containing GABAARs which underlie fast, synaptic, phasic inhibition have been implicated in sex differences in binge drinking. Ovarian hormones regulate δ-GABAARs, further implicating these receptors in potential sex differences. Here, we explored the contribution of extrasynaptic δ-GABAARs to male and female binge-like drinking in a critical area of mesolimbic circuitry-the ventral tegmental area (VTA). Quantitative PCR revealed higher Gabrd transcript levels and larger tonic currents in the VTA of females compared to males. In contrast, male and female Gabrg2 transcript levels and measures of phasic inhibition were equivalent. Intra-VTA infusion of AAV-Cre-GFP in floxed Gabrd mice downregulated δ-GABAARs and decreased binge-like drinking in females. There was no significant difference in either male or female mice after GABAAR γ2 subunit reduction in the VTA following AAV-Cre-GFP infusion in floxed Gabrg2 mice. Collectively, these findings suggest sex differences and GABAAR subunit specificity in alcohol intake.
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Affiliation(s)
- L M Darnieder
- Graduate Program in Neuroscience, Sackler School of Graduate Biomedical Sciences, Tufts University, Boston, MA, 02111, USA
| | - L C Melón
- Tufts University School of Medicine, Department of Neuroscience, Boston, MA, 02111, USA
| | - T Do
- Northeastern University, Bouvé College of Health Sciences, Boston, MA, 02115, USA
| | - N L Walton
- University of Massachusetts Boston, Honors College of Nursing and Health Sciences, Boston, MA, 02125, USA
| | - K A Miczek
- Tufts University School of Medicine, Department of Neuroscience, Boston, MA, 02111, USA
- Tufts University, Psychology Department, Medford, MA, 02155, USA
| | - J L Maguire
- Tufts University School of Medicine, Department of Neuroscience, Boston, MA, 02111, USA.
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Hannan S, Minere M, Harris J, Izquierdo P, Thomas P, Tench B, Smart TG. GABA AR isoform and subunit structural motifs determine synaptic and extrasynaptic receptor localisation. Neuropharmacology 2019; 169:107540. [PMID: 30794836 DOI: 10.1016/j.neuropharm.2019.02.022] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 02/06/2019] [Accepted: 02/14/2019] [Indexed: 12/27/2022]
Abstract
GABAA receptors (GABAARs) are the principal inhibitory neurotransmitter receptors in the central nervous system. They control neuronal excitability by synaptic and tonic forms of inhibition mostly mediated by different receptor subtypes located in specific cell membrane subdomains. A consensus suggests that α1-3βγ comprise synaptic GABAARs, whilst extrasynaptic α4βδ, α5βγ and αβ isoforms largely underlie tonic inhibition. Although some structural features that enable the spatial segregation of receptors are known, the mobility of key synaptic and extrasynaptic GABAARs are less understood, and yet this is a key determinant of the efficacy of GABA inhibition. To address this aspect, we have incorporated functionally silent α-bungarotoxin binding sites (BBS) into prominent hippocampal GABAAR subunits which mediate synaptic and tonic inhibition. Using single particle tracking with quantum dots we demonstrate that GABAARs that are traditionally considered to mediate synaptic or tonic inhibition are all able to access inhibitory synapses. These isoforms have variable diffusion rates and are differentially retained upon entering the synaptic membrane subdomain. Interestingly, α2 and α4 subunits reside longer at synapses compared to α5 and δ subunits. Furthermore, a high proportion of extrasynaptic δ-containing receptors exhibited slower diffusion compared to δ subunits at synapses. A chimera formed from δ-subunits, with the intracellular domain of γ2L, reversed this behaviour. In addition, we observed that receptor activation affected the diffusion of extrasynaptic, but not of synaptic GABAARs. Overall, we conclude that the differential mobility profiles of key synaptic and extrasynaptic GABAARs are determined by receptor subunit composition and intracellular structural motifs. This article is part of the special issue entitled 'Mobility and trafficking of neuronal membrane proteins'.
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Affiliation(s)
- Saad Hannan
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK.
| | - Marielle Minere
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Joseph Harris
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Pablo Izquierdo
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Philip Thomas
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Becky Tench
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Trevor G Smart
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK.
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Joshi S, Kapur J. Neurosteroid regulation of GABA A receptors: A role in catamenial epilepsy. Brain Res 2019; 1703:31-40. [PMID: 29481795 PMCID: PMC6107446 DOI: 10.1016/j.brainres.2018.02.031] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Revised: 09/08/2017] [Accepted: 02/20/2018] [Indexed: 12/31/2022]
Abstract
The female reproductive hormones progesterone and estrogen regulate network excitability. Fluctuations in the circulating levels of these hormones during the menstrual cycle cause frequent seizures during certain phases of the cycle in women with epilepsy. This seizure exacerbation, called catamenial epilepsy, is a dominant form of drug-refractory epilepsy in women of reproductive age. Progesterone, through its neurosteroid derivative allopregnanolone, increases γ-aminobutyric acid type-A receptor (GABAR)-mediated inhibition in the brain and keeps seizures under control. Catamenial seizures are believed to be a neurosteroid withdrawal symptom, and it was hypothesized that exogenous administration of progesterone to maintain its levels high during luteal phase will treat catamenial seizures. However, in a multicenter, double-blind, phase III clinical trial, progesterone treatment did not suppress catamenial seizures. The expression of GABARs with reduced neurosteroid sensitivity in epileptic animals may explain the failure of the progesterone clinical trial. The expression of neurosteroid-sensitive δ subunit-containing GABARs is reduced, and the expression of α4γ2 subunit-containing GABARs is upregulated, which alters the inhibition of dentate granule cells in epilepsy. These changes reduce the endogenous neurosteroid control of seizures and contribute to catamenial seizures.
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Affiliation(s)
- Suchitra Joshi
- Department of Neurology, University of Virginia, Charlottesville, VA 22908, United States.
| | - Jaideep Kapur
- Department of Neurology, University of Virginia, Charlottesville, VA 22908, United States; Department of Neuroscience, University of Virginia, Charlottesville, VA 22908, United States
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Zhou L, Tang X, Li X, Bai Y, Buxbaum JN, Chen G. Identification of transthyretin as a novel interacting partner for the δ subunit of GABAA receptors. PLoS One 2019; 14:e0210094. [PMID: 30615651 PMCID: PMC6322723 DOI: 10.1371/journal.pone.0210094] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 12/17/2018] [Indexed: 02/05/2023] Open
Abstract
GABAA receptors (GABAA-Rs) play critical roles in brain development and synchronization of neural network activity. While synaptic GABAA-Rs can exert rapid inhibition, the extrasynaptic GABAA-Rs can tonically inhibit neuronal activity due to constant activation by ambient GABA. The δ subunit-containing GABAA-Rs are expressed abundantly in the cerebellum, hippocampus and thalamus to mediate the major tonic inhibition in the brain. While electrophysiological and pharmacological properties of the δ-GABAA-Rs have been well characterized, the molecular interacting partners of the δ-GABAA-Rs are not clearly defined. Here, using a yeast two-hybrid screening assay, we identified transthyretin (TTR) as a novel regulatory molecule for the δ-GABAA-Rs. Knockdown of TTR in cultured cerebellar granule neurons significantly decreased the δ receptor expression; whereas overexpressing TTR in cortical neurons increased the δ receptor expression. Electrophysiological analysis confirmed that knockdown or overexpression of TTR in cultured neurons resulted in a corresponding decrease or increase of tonic currents. Furthermore, in vivo analysis of TTR-/- mice revealed a significant decrease of the surface expression of the δ-GABAA-Rs in cerebellar granule neurons. Together, our studies identified TTR as a novel regulator of the δ-GABAA-Rs.
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Affiliation(s)
- Li Zhou
- Department of Biology, Huck Institutes of Life Sciences, The Pennsylvania State University, University Park, PA, United States of America
| | - Xin Tang
- Department of Biology, Huck Institutes of Life Sciences, The Pennsylvania State University, University Park, PA, United States of America
| | - Xinyi Li
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA, United States of America
| | - Yuting Bai
- Department of Biology, Huck Institutes of Life Sciences, The Pennsylvania State University, University Park, PA, United States of America
| | - Joel N Buxbaum
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA, United States of America
| | - Gong Chen
- Department of Biology, Huck Institutes of Life Sciences, The Pennsylvania State University, University Park, PA, United States of America
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40
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Melón LC, Nasman JT, John AS, Mbonu K, Maguire JL. Interneuronal δ-GABA A receptors regulate binge drinking and are necessary for the behavioral effects of early withdrawal. Neuropsychopharmacology 2019; 44:425-434. [PMID: 30089884 PMCID: PMC6300562 DOI: 10.1038/s41386-018-0164-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 07/16/2018] [Accepted: 07/20/2018] [Indexed: 12/12/2022]
Abstract
Extensive evidence points to a role for GABAergic signaling in the amygdala in mediating the effects of alcohol, including presynaptic changes in GABA release, suggesting effects on GABAergic neurons. However, the majority of studies focus solely on the effects of alcohol on principal neurons. Here we demonstrate that δ-GABAARs, which have been suggested to confer ethanol sensitivity, are expressed at a high density on parvalbumin (PV) interneurons in the basolateral amygdala (BLA). Thus, we hypothesized that δ-GABAARs on PV interneurons may represent both an initial pharmacological target for alcohol and a site for plasticity associated with the expression of various behavioral maladaptations during withdrawal from binge drinking. To investigate this, we used a mouse model of voluntary alcohol intake (Drinking-in-the-Dark-Multiple Scheduled Access) to induce escalating heavy binge drinking and anxiety-like behavior in mice. This pattern of intake was associated with increased δ protein expression on parvalbumin positive interneurons in both the BLA and hippocampus. Loss of δ-GABAARs specifically in PV interneurons (PV:δ-/-) increased binge drinking behavior, reduced sensitivity to alcohol-induced motor incoordination, enhanced sensitivity to alcohol-induced hyperlocomotion and blocked the expression of withdrawal from binge drinking. This study is the first to demonstrate a role for δGABAARs specifically in PV-expressing interneurons in modulating binge alcohol intake and withdrawal-induced anxiety.
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Affiliation(s)
- Laverne C. Melón
- 0000 0000 8934 4045grid.67033.31Department of Neuroscience, Tufts University School of Medicine, Boston, MA 02111 USA
| | - James T. Nasman
- 0000 0000 8934 4045grid.67033.31Building Diversity in Biomedical Sciences, Tufts University School of Medicine, Boston, MA 02111 USA
| | - Ashley St. John
- 0000 0000 8934 4045grid.67033.31Building Diversity in Biomedical Sciences, Tufts University School of Medicine, Boston, MA 02111 USA
| | - Kenechukwu Mbonu
- 0000 0000 8934 4045grid.67033.31Building Diversity in Biomedical Sciences, Tufts University School of Medicine, Boston, MA 02111 USA
| | - Jamie L. Maguire
- 0000 0000 8934 4045grid.67033.31Department of Neuroscience, Tufts University School of Medicine, Boston, MA 02111 USA
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Liao Y, Liu X, Jounaidi Y, Forman SA, Feng HJ. Etomidate Effects on Desensitization and Deactivation of α4 β3 δ GABA A Receptors Inducibly Expressed in HEK293 TetR Cells. J Pharmacol Exp Ther 2019; 368:100-105. [PMID: 30389723 PMCID: PMC6304376 DOI: 10.1124/jpet.118.252403] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2018] [Accepted: 10/31/2018] [Indexed: 02/01/2023] Open
Abstract
Central α4βδ receptors are the most abundant isoform of δ subunit-containing extrasynaptic GABAA receptors that mediate tonic inhibition. Although the amplitude of GABA-activated currents through α4βδ receptors is modulated by multiple general anesthetics, the effects of general anesthetics on desensitization and deactivation of α4βδ receptors remain unknown. In the current study, we investigated the effect of etomidate, a potent general anesthetic, on the kinetics and the pseudo steady-state current amplitude of α4β3δ receptors inducibly expressed in human embryonic kidney 293 TetR cells. Etomidate directly activates α4β3δ receptors in a concentration-dependent manner. Etomidate at a clinically relevant concentration (3.2 μM) enhances maximal response without altering the EC50 of GABA concentration response. Etomidate also increases the extent of desensitization and prolongs the deactivation of α4β3δ receptors in the presence of maximally activating concentrations of GABA (1 mM). To mimic the modulatory effect of etomidate on tonic currents, long pulses (30-60 seconds) of a low GABA concentration (1 μM) were applied to activate α4β3δ receptors in the absence and presence of etomidate. Although etomidate increases the desensitization of α4β3δ receptors, the pseudo steady-state current amplitude at 1 μM GABA is augmented by etomidate. Our data demonstrate that etomidate enhances the pseudo steady-state current of α4β3δ receptors evoked by a GABA concentration comparable to an ambient GABA level, suggesting that α4β3δ receptors may mediate etomidate's anesthetic effect in the brain.
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Affiliation(s)
- Yiwei Liao
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts (Y.L., X.L., Y.J., S.A.F., H.-J.F.); Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, China (Y.L.); and Department of Anesthesia, The Sixth Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China (X.L.)
| | - Xiang Liu
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts (Y.L., X.L., Y.J., S.A.F., H.-J.F.); Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, China (Y.L.); and Department of Anesthesia, The Sixth Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China (X.L.)
| | - Youssef Jounaidi
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts (Y.L., X.L., Y.J., S.A.F., H.-J.F.); Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, China (Y.L.); and Department of Anesthesia, The Sixth Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China (X.L.)
| | - Stuart A Forman
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts (Y.L., X.L., Y.J., S.A.F., H.-J.F.); Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, China (Y.L.); and Department of Anesthesia, The Sixth Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China (X.L.)
| | - Hua-Jun Feng
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts (Y.L., X.L., Y.J., S.A.F., H.-J.F.); Department of Neurosurgery, Xiangya Hospital, Central South University, Changsha, China (Y.L.); and Department of Anesthesia, The Sixth Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China (X.L.)
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Hannapel R, Ramesh J, Ross A, LaLumiere RT, Roseberry AG, Parent MB. Postmeal Optogenetic Inhibition of Dorsal or Ventral Hippocampal Pyramidal Neurons Increases Future Intake. eNeuro 2019; 6:ENEURO.0457-18.2018. [PMID: 30693314 PMCID: PMC6348449 DOI: 10.1523/eneuro.0457-18.2018] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Accepted: 11/21/2018] [Indexed: 01/29/2023] Open
Abstract
Memory of a recently eaten meal can serve as a powerful mechanism for controlling future eating behavior because it provides a record of intake that likely outlasts most physiological signals generated by the meal. In support, impairing the encoding of a meal in humans increases the amount ingested at the next eating episode. However, the brain regions that mediate the inhibitory effects of memory on future intake are unknown. In the present study, we tested the hypothesis that dorsal hippocampal (dHC) and ventral hippocampal (vHC) glutamatergic pyramidal neurons play a critical role in the inhibition of energy intake during the postprandial period by optogenetically inhibiting these neurons at specific times relative to a meal. Male Sprague Dawley rats were given viral vectors containing CaMKIIα-eArchT3.0-eYFP or CaMKIIα-GFP and fiber optic probes into dHC of one hemisphere and vHC of the other. Compared to intake on a day in which illumination was not given, inhibition of dHC or vHC glutamatergic neurons after the end of a chow, sucrose, or saccharin meal accelerated the onset of the next meal and increased the amount consumed during that next meal when the neurons were no longer inhibited. Inhibition given during a meal did not affect the amount consumed during that meal or the next one but did hasten meal initiation. These data show that dHC and vHC glutamatergic neuronal activity during the postprandial period is critical for limiting subsequent ingestion and suggest that these neurons inhibit future intake by consolidating the memory of the preceding meal.
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Affiliation(s)
- Reilly Hannapel
- Neuroscience Institute, Georgia State University, Atlanta, GA 30303
| | - Janavi Ramesh
- Neuroscience Institute, Georgia State University, Atlanta, GA 30303
| | - Amy Ross
- Neuroscience Institute, Georgia State University, Atlanta, GA 30303
| | - Ryan T. LaLumiere
- Department of Psychological and Brain Sciences and Iowa Neuroscience Institute, University of Iowa, Iowa City, IA 52242
| | - Aaron G. Roseberry
- Neuroscience Institute, Georgia State University, Atlanta, GA 30303
- Department of Biology, Georgia State University, Atlanta, GA 30303
| | - Marise B. Parent
- Neuroscience Institute, Georgia State University, Atlanta, GA 30303
- Department of Psychology, Georgia State University, Atlanta, GA 30303
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Szodorai E, Bampali K, Romanov RA, Kasper S, Hökfelt T, Ernst M, Lubec G, Harkany T. Diversity matters: combinatorial information coding by GABA A receptor subunits during spatial learning and its allosteric modulation. Cell Signal 2018; 50:142-159. [DOI: 10.1016/j.cellsig.2018.07.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 07/08/2018] [Accepted: 07/09/2018] [Indexed: 01/11/2023]
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Lagrange AH, Hu N, Macdonald RL. GABA beyond the synapse: defining the subtype-specific pharmacodynamics of non-synaptic GABA A receptors. J Physiol 2018; 596:4475-4495. [PMID: 30019335 PMCID: PMC6138284 DOI: 10.1113/jp276187] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2018] [Accepted: 07/12/2018] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Physiologically relevant combinations of recombinant GABAA receptor (GABAR) subunits were expressed in HEK293 cells. Using whole-cell voltage clamp and rapid drug application, we measured the GABAR-subtype-specific properties to convey either synaptic or extrasynaptic signalling in a range of physiological contexts. α4βδ GABARs are optimally tuned to submicromolar tonic GABA and transient surges of micromolar GABA concentrations. α5β2γ2l GABARs are better suited to higher tonic GABA levels, but also convey robust responses to brief synaptic and perisynaptic GABA fluctuations. α1β2/3δ GABARs function well at prolonged, micromolar (>2 μm) GABA levels, but not to low tonic (<1 μm GABA) or synaptic/transient GABAergic signalling. These results help illuminate the context- and isoform-specific modes of GABAergic signalling in the brain. ABSTRACT GABAA receptors (GABARs) mediate a remarkable diversity of signalling modalities in vivo. Yet most published work characterizing responses to GABA has focused on the properties needed to convey fast, phasic synaptic inhibition. We therefore aimed to characterize the most prevalent (α4βδ, α5β3γ2L) and least prevalent (α1β2δ) non-synaptic GABAR currents, using whole-cell voltage clamp recordings of recombinant GABAR expressed in HEK293 cells and drug application protocols to recapitulate the GABA concentration profiles occurring during both fast synaptic and slow extrasynaptic signalling. We found that α4βδ GABARs were very sensitive to submicromolar GABA, with a rank order potency of α4β2δ ≥ α4β1δ ≈ α4β3δ GABARs. In comparison, the GABA EC50 was up to 20 times higher for α1β2γ2L GABARs, with α1β2δ and α5β3γ2L GABARs having intermediate GABA potency. Both α4βδ and α5β3γ2L GABAR currents exhibited slow, but substantial, desensitization as well as prolonged rates of deactivation. These GABAR current properties defined distinct 'dynamic ranges' of responsiveness to changing GABA for α4β2δ (0.1-1 μm), α5β3γ2L (0.5-7 μm) and α1β2γ2L (0.6-9 μm) GABARs. Finally, α1β2δ GABARs were notable for their relative lack of desensitization and extremely quick deactivation. In summary, our results help delineate the roles that specific GABARs may play in mediating non-synaptic GABA signals. Since ambient GABA levels may be altered during development as well as by drugs and disease states, these findings may help future efforts to understand disrupted inhibition underlying a variety of neurological illnesses, such as epilepsy.
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Affiliation(s)
- Andre H. Lagrange
- Departments of NeurologyVanderbilt University Medical CenterNashvilleTN37240‐7915USA
- PharmacologyVanderbilt University Medical CenterNashvilleTN37240‐7915USA
- Program in NeuroscienceVanderbilt University Medical CenterNashvilleTN37240‐7915USA
- Tennessee Valley Healthcare Systems Veterans AdministrationNashvilleTN37201USA
| | - NingNing Hu
- Departments of NeurologyVanderbilt University Medical CenterNashvilleTN37240‐7915USA
| | - Robert L. Macdonald
- Departments of NeurologyVanderbilt University Medical CenterNashvilleTN37240‐7915USA
- Molecular Physiology and BiophysicsVanderbilt University Medical CenterNashvilleTN37240‐7915USA
- PharmacologyVanderbilt University Medical CenterNashvilleTN37240‐7915USA
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Jiang Y, Xiao Y, Zhang X, Shu Y. Activation of axon initial segmental GABA A receptors inhibits action potential generation in neocortical GABAergic interneurons. Neuropharmacology 2018; 138:97-105. [PMID: 29883765 DOI: 10.1016/j.neuropharm.2018.05.026] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2018] [Revised: 05/14/2018] [Accepted: 05/20/2018] [Indexed: 10/16/2022]
Abstract
Ionotropic GABAA receptors expressing at the axon initial segment (AIS) of glutamatergic pyramidal cell (PC) in the cortex plays critical roles in regulating action potential generation. However, it remains unclear whether these receptors also express at the AIS of cortical GABAergic interneurons. In mouse prefrontal cortical slices, we performed experiments at the soma and AIS of the two most abundant GABAergic interneurons: parvalbumin (PV) and somatostatin (SST) positive neurons. Local application of GABA at the perisomatic axonal regions could evoke picrotoxin-sensitive currents with a reversal potential near the Cl- equilibrium potential. Puffing agonists to outside-out patches excised from AIS confirmed the expression of GABAA receptors. Further pharmacological experiments revealed that GABAA receptors in AIS of PV neurons contain α1 subunits, different from those containing α2/3 in AIS and α4 in axon trunk of layer-5 PCs. Cell-attached recording at the soma of PV and SST neurons revealed that the activation of AIS GABAA receptors inhibits the action potential generation induced by synaptic stimulation. Together, our results demonstrate that the AIS of PV and SST neurons express GABAA receptors with distinct subunit composition, which exert an inhibitory effect on neuronal excitability in these inhibitory interneurons.
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Affiliation(s)
- Yanbo Jiang
- Institute of Neuroscience and State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences and University of Chinese Academy of Sciences, Shanghai 200031, China
| | - Yujie Xiao
- State Key Laboratory of Cognitive Neuroscience and Learning, IDG/McGovern Institute for Brain Research, School of Brain and Cognitive Sciences, Beijing Normal University, Beijing 100875, China
| | - Xiaoxue Zhang
- State Key Laboratory of Cognitive Neuroscience and Learning, IDG/McGovern Institute for Brain Research, School of Brain and Cognitive Sciences, Beijing Normal University, Beijing 100875, China
| | - Yousheng Shu
- State Key Laboratory of Cognitive Neuroscience and Learning, IDG/McGovern Institute for Brain Research, School of Brain and Cognitive Sciences, Beijing Normal University, Beijing 100875, China.
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Lebedeva J, Zakharov A, Ogievetsky E, Minlebaeva A, Kurbanov R, Gerasimova E, Sitdikova G, Khazipov R. Inhibition of Cortical Activity and Apoptosis Caused by Ethanol in Neonatal Rats In Vivo. Cereb Cortex 2018; 27:1068-1082. [PMID: 26646511 DOI: 10.1093/cercor/bhv293] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Alcohol consumption during pregnancy causes fetal alcohol spectrum disorder, which includes neuroapoptosis and neurobehavioral deficits. The neuroapoptotic effects of alcohol have been hypothesized to involve suppression of brain activity. However, in vitro studies suggest that ethanol acts as a potent stimulant of cortical activity. We explored the effects of alcohol (1-6 g/kg) on electrical activity in the rat somatosensory cortex in vivo at postnatal days P1-23 and compared them with its apoptotic actions. At P4-7, when the peak of alcohol-induced apoptosis was observed, alcohol strongly suppressed spontaneous gamma and spindle-bursts and almost completely silenced neurons in a dose-dependent manner. The dose-dependence of suppression of neuronal activity strongly correlated with the alcohol-induced neuroapoptosis. Alcohol also profoundly inhibited sensory-evoked bursts and suppressed motor activity, a physiological trigger of cortical activity bursts in newborns. The suppressive effects of ethanol on neuronal activity waned during the second and third postnatal weeks, when instead of silencing the cortex, alcohol evoked delta-wave electrographic activity. Thus, the effects of alcohol on brain activity are strongly age-dependent, and during the first postnatal week alcohol profoundly inhibits brain activity. Our findings suggest that the adverse effects of alcohol in the developing brain involve suppression of neuronal activity.
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Affiliation(s)
- Julia Lebedeva
- Laboratory of Neurobiology, Kazan Federal University, Kazan, 420000, Russia.,INMED, INSERM U-901, Marseille, 13273, France.,Aix-Marseille University, Marseille, 13273, France
| | - Andrei Zakharov
- Laboratory of Neurobiology, Kazan Federal University, Kazan, 420000, Russia.,Department of Physiology, Kazan State Medical University, Kazan, 420012, Russia
| | - Elena Ogievetsky
- INMED, INSERM U-901, Marseille, 13273, France.,Aix-Marseille University, Marseille, 13273, France
| | - Alina Minlebaeva
- INMED, INSERM U-901, Marseille, 13273, France.,Aix-Marseille University, Marseille, 13273, France
| | - Rustem Kurbanov
- Laboratory of Neurobiology, Kazan Federal University, Kazan, 420000, Russia
| | - Elena Gerasimova
- Laboratory of Neurobiology, Kazan Federal University, Kazan, 420000, Russia
| | - Guzel Sitdikova
- Laboratory of Neurobiology, Kazan Federal University, Kazan, 420000, Russia
| | - Roustem Khazipov
- Laboratory of Neurobiology, Kazan Federal University, Kazan, 420000, Russia.,INMED, INSERM U-901, Marseille, 13273, France.,Aix-Marseille University, Marseille, 13273, France
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Yakoub K, Jung S, Sattler C, Damerow H, Weber J, Kretzschmann A, Cankaya AS, Piel M, Rösch F, Haugaard AS, Frølund B, Schirmeister T, Lüddens H. Structure–Function Evaluation of Imidazopyridine Derivatives Selective for δ-Subunit-Containing γ-Aminobutyric Acid Type A (GABAA) Receptors. J Med Chem 2018; 61:1951-1968. [DOI: 10.1021/acs.jmedchem.7b01484] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Kirsten Yakoub
- Department of Psychiatry and Psychotherapy, Faculty of Health and Medical Sciences, University Medical Center Mainz, D-55131 Mainz, Germany
| | | | - Christian Sattler
- Department of Psychiatry and Psychotherapy, Faculty of Health and Medical Sciences, University Medical Center Mainz, D-55131 Mainz, Germany
| | | | | | | | | | | | | | - Anne S. Haugaard
- Department of Drug Design and Pharmacology, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Bente Frølund
- Department of Drug Design and Pharmacology, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | | | - Hartmut Lüddens
- Department of Psychiatry and Psychotherapy, Faculty of Health and Medical Sciences, University Medical Center Mainz, D-55131 Mainz, Germany
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Mallard TT, Ashenhurst JR, Harden KP, Fromme K. GABRA2, alcohol, and illicit drug use: An event-level model of genetic risk for polysubstance use. JOURNAL OF ABNORMAL PSYCHOLOGY 2018; 127:190-201. [PMID: 29528673 PMCID: PMC5851473 DOI: 10.1037/abn0000333] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
GABRA2, the gene encoding the α2 subunit of the GABAA receptor, potentially plays a role in the etiology of problematic drinking, as GABRA2 genotype has been associated with subjective response to alcohol and other alcohol-related reward processes. The GABRA2 gene has also been associated with illicit drug use, but the extent to which associations with drug use are independent of associations with alcohol use remains unclear, partly because most previous research has used a cross-sectional design that cannot discriminate comorbidity at the between-person level and co-occurrence within-persons. The present study used a daily monitoring method that assessed the effects of GABRA2 variation on substance use as it occurred in the natural environment during emerging adulthood. Non-Hispanic European participants provided DNA samples and completed daily reports of alcohol and drug use for 1 month per year across 4 years (N = 28,263 unique observations of N = 318 participants). GABRA2 variants were associated with illicit drug use in both sober and intoxicated conditions. Moreover, the effect of GABRA2 variation on drug use was moderated by an individual's degree of intoxication. These findings are consistent with recent genetic and neuroscience research, and they suggest GABRA2 variation influences drug-seeking behavior through both alcohol-related and alcohol-independent pathways. (PsycINFO Database Record
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Affiliation(s)
| | | | - K Paige Harden
- Department of Psychology, The University of Texas at Austin
| | - Kim Fromme
- Department of Psychology, The University of Texas at Austin
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Feng HJ, Forman SA. Comparison of αβδ and αβγ GABA A receptors: Allosteric modulation and identification of subunit arrangement by site-selective general anesthetics. Pharmacol Res 2017; 133:289-300. [PMID: 29294355 DOI: 10.1016/j.phrs.2017.12.031] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Revised: 12/28/2017] [Accepted: 12/29/2017] [Indexed: 12/27/2022]
Abstract
GABAA receptors play a dominant role in mediating inhibition in the mature mammalian brain, and defects of GABAergic neurotransmission contribute to the pathogenesis of a variety of neurological and psychiatric disorders. Two types of GABAergic inhibition have been described: αβγ receptors mediate phasic inhibition in response to transient high-concentrations of synaptic GABA release, and αβδ receptors produce tonic inhibitory currents activated by low-concentration extrasynaptic GABA. Both αβδ and αβγ receptors are important targets for general anesthetics, which induce apparently different changes both in GABA-dependent receptor activation and in desensitization in currents mediated by αβγ vs. αβδ receptors. Many of these differences are explained by correcting for the high agonist efficacy of GABA at most αβγ receptors vs. much lower efficacy at αβδ receptors. The stoichiometry and subunit arrangement of recombinant αβγ receptors are well established as β-α-γ-β-α, while those of αβδ receptors remain controversial. Importantly, some potent general anesthetics selectively bind in transmembrane inter-subunit pockets of αβγ receptors: etomidate acts at β+/α- interfaces, and the barbiturate R-5-allyl-1-methyl-5-(m-trifluoromethyl-diazirynylphenyl) barbituric acid (R-mTFD-MPAB) acts at α+/β- and γ+/β- interfaces. Thus, these drugs are useful as structural probes in αβδ receptors formed from free subunits or concatenated subunit assemblies designed to constrain subunit arrangement. Although a definite conclusion cannot be drawn, studies using etomidate and R-mTFD-MPAB support the idea that recombinant α1β3δ receptors may share stoichiometry and subunit arrangement with α1β3γ2 receptors.
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Affiliation(s)
- Hua-Jun Feng
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, and Department of Anesthesia, Harvard Medical School, Boston, MA 02114, USA.
| | - Stuart A Forman
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, and Department of Anesthesia, Harvard Medical School, Boston, MA 02114, USA.
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Schaefer SM, Vives Rodriguez A, Louis ED. Brain circuits and neurochemical systems in essential tremor: insights into current and future pharmacotherapeutic approaches. Expert Rev Neurother 2017; 18:101-110. [PMID: 29206482 DOI: 10.1080/14737175.2018.1413353] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
INTRODUCTION There are few medications that are available for the treatment of essential tremor (ET) and they are only moderately effective. Areas covered: Data were obtained from a PubMed search. Original articles, review articles, and clinical guidelines were included. Two disease models for ET have been proposed: 1) the olivary model, which attributes ET to a pathological pacemaker in the inferior olivary nucleus, and 2) the cerebellar degeneration model, which postulates that ET originates in the cerebellum and could be related to deficient or abnormal Purkinje cell (PC) output. Underlying biochemical dysfunction in T-type calcium channels (T-tCaC) may loosely be linked to the first model and deficiency/abnormality in γ-aminobutyric acid (GABA) neurotransmission, to the second. Expert commentary: Human data points robustly to the role of GABA in ET. Numerous medications that target the GABA system have been tried, with variable success. Given the many different types of GABA-ergic neurons, and the multitude of GABAA receptor subtypes, a given medication could have competing/cancelling effects. It would seem that influencing GABA receptors broadly is not as effective as targeting certain GABAA receptor subtypes. Future research should seek to identify molecular candidates that have a more targeted effect within the GABA system.
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Affiliation(s)
- Sara M Schaefer
- a Department of Neurology , Yale School of Medicine, Yale University , New Haven , CT , USA
| | - Ana Vives Rodriguez
- a Department of Neurology , Yale School of Medicine, Yale University , New Haven , CT , USA
| | - Elan D Louis
- a Department of Neurology , Yale School of Medicine, Yale University , New Haven , CT , USA.,b Department of Chronic Disease Epidemiology , Yale School of Public Health, Yale University , New Haven , CT , USA.,c Center for Neuroepidemiology and Clinical Neurological Research, Yale School of Medicine , Yale University , New Haven , CT , USA
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