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α6-Containing GABAA Receptors Are the Principal Mediators of Inhibitory Synapse Strengthening by Insulin in Cerebellar Granule Cells. J Neurosci 2015; 35:9676-88. [PMID: 26134650 DOI: 10.1523/jneurosci.0513-15.2015] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Activity-dependent strengthening of central synapses is a key factor driving neuronal circuit behavior in the vertebrate CNS. At fast inhibitory synapses, strengthening is thought to occur by increasing the number of GABAA receptors (GABARs) of the same subunit composition to preexisting synapses. Here, we show that strengthening of mouse cerebellar granule cell GABAergic synapses occurs by a different mechanism. Specifically, we show that the neuropeptide hormone, insulin, strengthens inhibitory synapses by recruiting α6-containing GABARs rather than accumulating more α1-containing receptors that are resident to the synapse. Because α6-receptors are targeted to functionally distinct postsynaptic sites from α1-receptors, we conclude that only a subset of all inhibitory synapses are strengthened. Together with our recent findings on stellate cells, we propose a general mechanism by which mature inhibitory synapses are strengthened. In this scenario, α1-GABARs resident to inhibitory synapses form the hardwiring of neuronal circuits with receptors of a different composition fulfilling a fundamental, but unappreciated, role in synapse strengthening.
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202
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Johansson M, Agusti A, Llansola M, Montoliu C, Strömberg J, Malinina E, Ragagnin G, Doverskog M, Bäckström T, Felipo V. GR3027 antagonizes GABAA receptor-potentiating neurosteroids and restores spatial learning and motor coordination in rats with chronic hyperammonemia and hepatic encephalopathy. Am J Physiol Gastrointest Liver Physiol 2015; 309:G400-9. [PMID: 26138462 PMCID: PMC4556948 DOI: 10.1152/ajpgi.00073.2015] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 06/29/2015] [Indexed: 01/31/2023]
Abstract
Hepatic encephalopathy (HE) is one of the primary complications of liver cirrhosis. Current treatments for HE, mainly directed to reduction of ammonia levels, are not effective enough because they cannot completely eliminate hyperammonemia and inflammation, which induce the neurological alterations. Studies in animal models show that overactivation of GABAA receptors is involved in cognitive and motor impairment in HE and that reducing this activation restores these functions. We have developed a new compound, GR3027, that selectively antagonizes the enhanced activation of GABAA receptors by neurosteroids such as allopregnanolone and 3α,21-dihydroxy-5α-pregnan-20-one (THDOC). This work aimed to assess whether GR3027 improves motor incoordination, spatial learning, and circadian rhythms of activity in rats with HE. GR3027 was administered subcutaneously to two main models of HE: rats with chronic hyperammonemia due to ammonia feeding and rats with portacaval shunts (PCS). Motor coordination was assessed in beam walking and spatial learning and memory in the Morris water maze and the radial maze. Circadian rhythms of ambulatory and vertical activity were also assessed. In both hyperammonemic and PCS rats, GR3027 restores motor coordination, spatial memory in the Morris water maze, and spatial learning in the radial maze. GR3027 also partially restores circadian rhythms of ambulatory and vertical activity in PCS rats. GR3027 is a novel approach to treatment of HE that would normalize neurological functions altered because of enhanced GABAergic tone, affording more complete normalization of cognitive and motor function than current treatments for HE.
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Affiliation(s)
- Maja Johansson
- 1Umecrine Cognition AB, Solna, Sweden; ,2Umeå Neurosteroid Research Center, Department of Clinical Sciences, Umeå University, Umeå, Sweden;
| | | | | | | | - Jessica Strömberg
- 2Umeå Neurosteroid Research Center, Department of Clinical Sciences, Umeå University, Umeå, Sweden;
| | - Evgenya Malinina
- 2Umeå Neurosteroid Research Center, Department of Clinical Sciences, Umeå University, Umeå, Sweden;
| | - Gianna Ragagnin
- 2Umeå Neurosteroid Research Center, Department of Clinical Sciences, Umeå University, Umeå, Sweden;
| | | | - Torbjörn Bäckström
- 2Umeå Neurosteroid Research Center, Department of Clinical Sciences, Umeå University, Umeå, Sweden;
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203
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Transcriptional regulation of GAD1 GABA synthesis gene in the prefrontal cortex of subjects with schizophrenia. Schizophr Res 2015; 167:28-34. [PMID: 25458568 PMCID: PMC4417100 DOI: 10.1016/j.schres.2014.10.020] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Revised: 10/08/2014] [Accepted: 10/13/2014] [Indexed: 12/20/2022]
Abstract
Expression of GAD1 GABA synthesis enzyme is highly regulated by neuronal activity and reaches mature levels in the prefrontal cortex not before adolescence. A significant portion of cases diagnosed with schizophrenia show deficits in GAD1 RNA and protein levels in multiple areas of adult cerebral cortex, possibly reflecting molecular or cellular defects in subtypes of GABAergic interneurons essential for network synchronization and cognition. Here, we review 20years of progress towards a better understanding of disease-related regulation of GAD1 gene expression. For example, deficits in cortical GAD1 RNA in some cases of schizophrenia are associated with changes in the epigenetic architecture of the promoter, affecting DNA methylation patterns and nucleosomal histone modifications. These localized chromatin defects at the 5' end of GAD1 are superimposed by disordered locus-specific chromosomal conformations, including weakening of long-range promoter-enhancer loopings and physical disconnection of GAD1 core promoter sequences from cis-regulatory elements positioned 50 kilobases further upstream. Studies on the 3-dimensional architecture of the GAD1 locus in neurons, including developmentally regulated higher order chromatin compromised by the disease process, together with exploration of locus-specific epigenetic interventions in animal models, could pave the way for future treatments of psychosis and schizophrenia.
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204
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GABA abnormalities in schizophrenia: a methodological review of in vivo studies. Schizophr Res 2015; 167:84-90. [PMID: 25458856 PMCID: PMC4409914 DOI: 10.1016/j.schres.2014.10.011] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2014] [Revised: 10/04/2014] [Accepted: 10/07/2014] [Indexed: 12/31/2022]
Abstract
Abnormalities of GABAergic interneurons are some of the most consistent findings from post-mortem studies of schizophrenia. However, linking these molecular deficits with in vivo observations in patients - a critical goal in order to evaluate interventions that would target GABAergic deficits - presents a challenge. Explanatory models have been developed based on animal work and the emerging experimental literature in schizophrenia patients. This literature includes: neuroimaging ligands to GABA receptors, magnetic resonance spectroscopy (MRS) of GABA concentration, transcranial magnetic stimulation of cortical inhibitory circuits and pharmacologic probes of GABA receptors to dynamically challenge the GABA system, usually in combination with neuroimaging studies. Pharmacologic challenges have elicited behavioral changes, and preliminary studies of therapeutic GABAergic interventions have been conducted. This article critically reviews the evidence for GABAergic dysfunction from each of these areas. These methods remain indirect measures of GABAergic function, and a broad array of dysfunction is linked with the putative GABAergic measures, including positive symptoms, cognition, emotion, motor processing and sensory processing, covering diverse brain areas. Measures of receptor binding have not shown replicable group differences in binding, and MRS assays of GABA concentration have yielded equivocal evidence of large-scale alteration in GABA concentration. Overall, the experimental base remains sparse, and much remains to be learned about the role of GABAergic interneurons in healthy brains. Challenges with pharmacologic and functional probes show promise, and may yet enable a better characterization of GABAergic deficits in schizophrenia.
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205
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Stamenić TT, Joksimović S, Biawat P, Stanković T, Marković B, Cook JM, Savić MM. Negative modulation of α₅ GABAA receptors in rats may partially prevent memory impairment induced by MK-801, but not amphetamine- or MK-801-elicited hyperlocomotion. J Psychopharmacol 2015; 29:1013-24. [PMID: 26105958 PMCID: PMC4861997 DOI: 10.1177/0269881115590601] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Reportedly, negative modulation of α5 GABAA receptors may improve cognition in normal and pharmacologically-impaired animals, and such modulation has been proposed as an avenue for treatment of cognitive symptoms in schizophrenia. This study assessed the actions of PWZ-029, administered at doses (2, 5, and 10 mg/kg) at which it reached micromolar concentrations in brain tissue with estimated free concentrations adequate for selective modulation of α5 GABAA receptors, in three cognitive tasks in male Wistar rats acutely treated with the noncompetitive N-methyl-d-aspartate receptor antagonist, MK-801 (0.1 mg/kg), as well in tests of locomotor activity potentiated by MK-801 (0.2 mg/kg) or amphetamine (0.5 mg/kg). In a hormetic-like manner, only 5 mg/kg PWZ-029 reversed MK-801-induced deficits in novel object recognition test (visual recognition memory), whereas in the Morris water maze, the 2 mg/kg dose of PWZ-029 exerted partial beneficial effects on spatial learning impairment. PWZ-029 did not affect recognition memory deficits in social novelty discrimination procedure. Motor hyperactivity induced with MK-801 or amphetamine was not preventable by PWZ-029. Our results show that certain MK-801-induced memory deficits can be ameliorated by negative modulation of α5 GABAA receptors, and point to the need for further elucidation of their translational relevance to cognitive deterioration in schizophrenia.
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Affiliation(s)
| | - Srdjan Joksimović
- Department of Pharmacology, University of Belgrade, Belgrade, Serbia
| | - Poonam Biawat
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Tamara Stanković
- Department of Pharmacology, University of Belgrade, Belgrade, Serbia
| | - Bojan Marković
- Department of Pharmaceutical Chemistry, University of Belgrade, Belgrade, Serbia
| | - James M Cook
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Miroslav M Savić
- Department of Pharmacology, University of Belgrade, Belgrade, Serbia
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206
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Martin BS, Martinez-Botella G, Loya CM, Salituro FG, Robichaud AJ, Huntsman MM, Ackley MA, Doherty JJ, Corbin JG. Rescue of deficient amygdala tonic γ-aminobutyric acidergic currents in the Fmr-/y mouse model of fragile X syndrome by a novel γ-aminobutyric acid type A receptor-positive allosteric modulator. J Neurosci Res 2015; 94:568-78. [PMID: 26308557 DOI: 10.1002/jnr.23632] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Revised: 08/01/2015] [Accepted: 08/04/2015] [Indexed: 11/07/2022]
Abstract
Alterations in the ratio of excitatory to inhibitory transmission are emerging as a common component of many nervous system disorders, including autism spectrum disorders (ASDs). Tonic γ-aminobutyric acidergic (GABAergic) transmission provided by peri- and extrasynaptic GABA type A (GABAA ) receptors powerfully controls neuronal excitability and plasticity and, therefore, provides a rational therapeutic target for normalizing hyperexcitable networks across a variety of disorders, including ASDs. Our previous studies revealed tonic GABAergic deficits in principal excitatory neurons in the basolateral amygdala (BLA) in the Fmr1(-/y) knockout (KO) mouse model fragile X syndrome. To correct amygdala deficits in tonic GABAergic neurotransmission in Fmr1(-/y) KO mice, we developed a novel positive allosteric modulator of GABAA receptors, SGE-872, based on endogenously active neurosteroids. This study shows that SGE-872 is nearly as potent and twice as efficacious for positively modulating GABAA receptors as its parent molecule, allopregnanolone. Furthermore, at submicromolar concentrations (≤1 μM), SGE-872 is selective for tonic, extrasynaptic α4β3δ-containing GABAA receptors over typical synaptic α1β2γ2 receptors. We further find that SGE-872 strikingly rescues the tonic GABAergic transmission deficit in principal excitatory neurons in the Fmr1(-/y) KO BLA, a structure heavily implicated in the neuropathology of ASDs. Therefore, the potent and selective action of SGE-872 on tonic GABAA receptors containing α4 subunits may represent a novel and highly useful therapeutic avenue for ASDs and related disorders involving hyperexcitability of neuronal networks.
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Affiliation(s)
- Brandon S Martin
- Center for Neuroscience Research, Children's National Medical Center, Washington, DC
| | | | - Carlos M Loya
- SAGE Therapeutics, 215 First Street, Cambridge, MA 0214243
| | | | | | - Molly M Huntsman
- Pharmaceutical Sciences and Department of Pediatrics, School of Medicine, University of Colorado, Anschutz Medical Campus, Aurora, Colorado
| | - Mike A Ackley
- SAGE Therapeutics, 215 First Street, Cambridge, MA 0214243
| | | | - Joshua G Corbin
- Center for Neuroscience Research, Children's National Medical Center, Washington, DC
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207
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Abstract
Intellectual disability, autism spectrum disorder, and epilepsy are prime examples of neurodevelopmental disorders that collectively affect a significant percentage of the world population. Recent technological breakthroughs allowed the elucidation of the genetic causes of many of these disorders. As neurodevelopmental disorders are genetically heterogeneous, the development of rational therapy is extremely challenging. Fortunately, many causative genes are interconnected and cluster in specific cellular pathways. Targeting a common node in such a network would allow us to interfere with a series of related neurodevelopmental disorders at once. Here, we argue that the GABAergic system is disturbed in many neurodevelopmental disorders, including fragile X syndrome, Rett syndrome, and Dravet syndrome, and is a key candidate target for therapeutic intervention. Many drugs that modulate the GABAergic system have already been tested in animal models with encouraging outcomes and are readily available for clinical trials.
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Affiliation(s)
- Sien Braat
- Department of Medical Genetics, University of Antwerp, Prins Boudewijnlaan 43, 2650 Edegem, Belgium
| | - R Frank Kooy
- Department of Medical Genetics, University of Antwerp, Prins Boudewijnlaan 43, 2650 Edegem, Belgium.
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208
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Ling I, Mihalik B, Etherington LA, Kapus G, Pálvölgyi A, Gigler G, Kertész S, Gaál A, Pallagi K, Kiricsi P, Szabó É, Szénási G, Papp L, Hársing LG, Lévay G, Spedding M, Lambert JJ, Belelli D, Barkóczy J, Volk B, Simig G, Gacsályi I, Antoni FA. A novel GABA(A) alpha 5 receptor inhibitor with therapeutic potential. Eur J Pharmacol 2015; 764:497-507. [PMID: 26169564 DOI: 10.1016/j.ejphar.2015.07.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Revised: 06/30/2015] [Accepted: 07/01/2015] [Indexed: 10/23/2022]
Abstract
Novel 2,3-benzodiazepine and related isoquinoline derivatives, substituted at position 1 with a 2-benzothiophenyl moiety, were synthesized to produce compounds that potently inhibited the action of GABA on heterologously expressed GABAA receptors containing the alpha 5 subunit (GABAA α5), with no apparent affinity for the benzodiazepine site. Substitutions of the benzothiophene moiety at position 4 led to compounds with drug-like properties that were putative inhibitors of extra-synaptic GABAA α5 receptors and had substantial blood-brain barrier permeability. Initial characterization in vivo showed that 8-methyl-5-[4-(trifluoromethyl)-1-benzothiophen-2-yl]-1,9-dihydro-2H-[1,3]oxazolo[4,5-h][2,3]benzodiazepin-2-one was devoid of sedative, pro-convulsive or motor side-effects, and enhanced the performance of rats in the object recognition test. In summary, we have discovered a first-in-class GABA-site inhibitor of extra-synaptic GABAA α5 receptors that has promising drug-like properties and warrants further development.
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Affiliation(s)
- István Ling
- Chemical Research Division, Egis Pharmaceuticals PLC, Budapest, Hungary
| | - Balázs Mihalik
- Division of Preclinical Research, Egis Pharmaceuticals PLC, Budapest, Hungary
| | - Lori-An Etherington
- Division of Neuroscience, Medical Research Institute, Ninewells Hospital & Medical School, Dundee University, Dundee, Scotland, UK
| | - Gábor Kapus
- Division of Preclinical Research, Egis Pharmaceuticals PLC, Budapest, Hungary
| | - Adrienn Pálvölgyi
- Division of Preclinical Research, Egis Pharmaceuticals PLC, Budapest, Hungary
| | - Gábor Gigler
- Division of Preclinical Research, Egis Pharmaceuticals PLC, Budapest, Hungary
| | - Szabolcs Kertész
- Division of Preclinical Research, Egis Pharmaceuticals PLC, Budapest, Hungary
| | - Attila Gaál
- Division of Preclinical Research, Egis Pharmaceuticals PLC, Budapest, Hungary
| | - Katalin Pallagi
- Division of Preclinical Research, Egis Pharmaceuticals PLC, Budapest, Hungary
| | - Péter Kiricsi
- Division of Preclinical Research, Egis Pharmaceuticals PLC, Budapest, Hungary
| | - Éva Szabó
- Division of Preclinical Research, Egis Pharmaceuticals PLC, Budapest, Hungary
| | - Gábor Szénási
- Division of Preclinical Research, Egis Pharmaceuticals PLC, Budapest, Hungary
| | - Lilla Papp
- Division of Preclinical Research, Egis Pharmaceuticals PLC, Budapest, Hungary
| | - László G Hársing
- Division of Preclinical Research, Egis Pharmaceuticals PLC, Budapest, Hungary
| | - György Lévay
- Division of Preclinical Research, Egis Pharmaceuticals PLC, Budapest, Hungary
| | | | - Jeremy J Lambert
- Division of Neuroscience, Medical Research Institute, Ninewells Hospital & Medical School, Dundee University, Dundee, Scotland, UK
| | - Delia Belelli
- Division of Neuroscience, Medical Research Institute, Ninewells Hospital & Medical School, Dundee University, Dundee, Scotland, UK
| | - József Barkóczy
- Chemical Research Division, Egis Pharmaceuticals PLC, Budapest, Hungary
| | - Balázs Volk
- Chemical Research Division, Egis Pharmaceuticals PLC, Budapest, Hungary
| | - Gyula Simig
- Chemical Research Division, Egis Pharmaceuticals PLC, Budapest, Hungary
| | - István Gacsályi
- Division of Preclinical Research, Egis Pharmaceuticals PLC, Budapest, Hungary
| | - Ferenc A Antoni
- Division of Preclinical Research, Egis Pharmaceuticals PLC, Budapest, Hungary.
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209
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McQuail JA, Frazier CJ, Bizon JL. Molecular aspects of age-related cognitive decline: the role of GABA signaling. Trends Mol Med 2015; 21:450-60. [PMID: 26070271 DOI: 10.1016/j.molmed.2015.05.002] [Citation(s) in RCA: 127] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Revised: 05/12/2015] [Accepted: 05/14/2015] [Indexed: 12/19/2022]
Abstract
Alterations in inhibitory interneurons contribute to cognitive deficits associated with several psychiatric and neurological diseases. Phasic and tonic inhibition imparted by γ-aminobutyric acid (GABA) receptors regulates neural activity and helps to establish the appropriate network dynamics in cortical circuits that support normal cognition. This review highlights basic science demonstrating that inhibitory signaling is altered in aging, and discusses the impact of age-related shifts in inhibition on different forms of memory function, including hippocampus-dependent spatial reference memory and prefrontal cortex (PFC)-dependent working memory. The clinical appropriateness and tractability of select therapeutic candidates for cognitive aging that target receptors mediating inhibition are also discussed.
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Affiliation(s)
- Joseph A McQuail
- Department of Neuroscience, University of Florida, Gainesville, FL 32610, USA; McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
| | - Charles J Frazier
- Department of Neuroscience, University of Florida, Gainesville, FL 32610, USA; McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA; Department of Pharmacodynamics, University of Florida, Gainesville, FL 32610, USA
| | - Jennifer L Bizon
- Department of Neuroscience, University of Florida, Gainesville, FL 32610, USA; McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA.
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210
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Paine TA, Cooke EK, Lowes DC. Effects of chronic inhibition of GABA synthesis on attention and impulse control. Pharmacol Biochem Behav 2015; 135:97-104. [PMID: 26044967 DOI: 10.1016/j.pbb.2015.05.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Revised: 05/23/2015] [Accepted: 05/28/2015] [Indexed: 11/30/2022]
Abstract
BACKGROUND Cortical GABA regulates a number of cognitive functions including attention and working memory and is dysregulated in a number of psychiatric conditions. In schizophrenia for example, changes in GABA neurons [reduced expression of glutamic acid decarboxylase (GAD), parvalbumin (PV) and the GABA reuptake transporter (GAT1)] suggest reduced cortical GABA synthesis and release; these changes are hypothesized to cause the cognitive deficits observed in this disorder. The goals of this experiment were to determine whether chronically reducing GAD function within the rat PFC causes attention deficits and alterations in PV and GAT1 expression. METHODS Male Sprague Dawley rats were trained on the 5-choice serial reaction time task (5CSRTT, a task of attention) until they reached criterion performance and then were implanted with a bilateral cannula aimed at the medial PFC. Cannulae were connected to osmotic minipumps that infused the GAD inhibitor l-allylglycine (LAG, 3.2μg/0.5μl/h) for 13days. Following a 5-day recovery from surgery rats were tested on the standard 5CSRTT for 5 consecutive days and then tested on two modifications of the 5CSRTT. Finally, locomotor activity was assessed and the rats sacrificed. Brains were rapidly extracted and flash frozen and analyzed for the expression of GAD67, PV, GAT1 and the obligatory NMDA receptor subunit NR1. RESULTS Chronic LAG infusions transiently impaired attention, persistently impaired impulse control and increased locomotor activity. Behavioral changes were associated with an upregulation of GAD67, but no change in PV, GAT1 or NR1 expression. SUMMARY Chronic inhibition of GABA synthesis within the medial PFC, increased impulsive behavior and locomotion, but did not impair attention; results consistent with previous research following acute inhibition of GABA synthesis. Moreover, our data do not support the hypothesis that decreasing GABA synthesis and release is sufficient to cause changes in other GABA-related proteins.
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Affiliation(s)
- Tracie A Paine
- Department of Neuroscience, Oberlin College, Oberlin OH, 44074, USA.
| | | | - Daniel C Lowes
- Department of Neuroscience, Oberlin College, Oberlin OH, 44074, USA
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211
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Abstract
γ-Aminobutyric acid (GABA) binds to ionotropic GABAA receptors to mediate fast inhibitory synaptic transmission in the central nervous system (CNS). GABAA receptors are pentameric structures composed of receptor subunits (α1-6, β1-3, γ1-3, δ, ε, θ, π, ρ1-3) with various stoichiometries. They play important roles in the control of neural networks and are the pharmacological targets for the treatment of diseases such as epilepsy, autism, and schizophrenia. Thus far, there has been no report on GABA synaptic transmission in developing zebrafish. Here we used whole-cell patch-clamp electrophysiology to record GABAA-mediated miniature postsynaptic currents from the Mauthner cells of embryonic zebrafish. Spontaneous GABAA currents occurred infrequently and were low in amplitude (27.2 ± 0.9 pA). Analysis of their kinetics suggested the existence of three main types of events: the first (group I) is mediated by a single type of receptor with decay kinetics of 54 ± 1.6 ms; the second (group II) is also mediated by a single receptor type, but exhibits significantly longer decay kinetics (151 ± 7.2 ms); and the third type of synapse (group III) contains multiple receptor types with fast (τ1=28.7 ± 2.5 ms) and slow (τ2=153 ± 11 ms) kinetics. Thus, for the first time, we report the properties of GABA synaptic currents associated with the Mauthner cells of zebrafish.
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212
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Effects of disrupting medial prefrontal cortex GABA transmission on decision-making in a rodent gambling task. Psychopharmacology (Berl) 2015; 232:1755-65. [PMID: 25420610 PMCID: PMC4412766 DOI: 10.1007/s00213-014-3816-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Accepted: 11/08/2014] [Indexed: 12/18/2022]
Abstract
RATIONALE Decision-making is a complex cognitive process that is mediated, in part, by subregions of the medial prefrontal cortex (PFC). Decision-making is impaired in a number of psychiatric conditions including schizophrenia. Notably, people with schizophrenia exhibit reductions in GABA function in the same PFC areas that are implicated in decision-making. For example, expression of the GABA-synthesizing enzyme GAD67 is reduced in the dorsolateral PFC of people with schizophrenia. OBJECTIVES The goal of this experiment was to determine whether disrupting cortical GABA transmission impairs decision-making using a rodent gambling task (rGT). METHODS Rats were trained on the rGT until they reached stable performance and then were implanted with guide cannulae aimed at the medial PFC. Following recovery, the effects of intra-PFC infusions of the GABAA receptor antagonist bicuculline methiodide (BMI) or the GABA synthesis inhibitor L-allylglycine (LAG) on performance on the rGT were assessed. RESULTS Intracortical infusions of BMI (25 ng/μl/side), but not LAG (10 μg/μl/side), altered decision-making. Following BMI infusions, rats made fewer advantageous choices. Follow-up experiments suggested that the change in decision-making was due to a change in the sensitivity to the punishments, rather than a change in the sensitivity to reward magnitudes, associated with each outcome. LAG infusions increased premature responding, a measure of response inhibition, but did not affect decision-making. CONCLUSIONS Blocking GABAA receptors, but not inhibiting cortical GABA synthesis, within the medial PFC affects decision-making in the rGT. These data provide proof-of-concept evidence that disruptions in GABA transmission can contribute to the decision-making deficits in schizophrenia.
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213
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Ralvenius WT, Benke D, Acuña MA, Rudolph U, Zeilhofer HU. Analgesia and unwanted benzodiazepine effects in point-mutated mice expressing only one benzodiazepine-sensitive GABAA receptor subtype. Nat Commun 2015; 6:6803. [PMID: 25865415 PMCID: PMC4829939 DOI: 10.1038/ncomms7803] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Accepted: 03/02/2015] [Indexed: 01/19/2023] Open
Abstract
Agonists at the benzodiazepine-binding site of GABAA receptors (BDZs) enhance synaptic inhibition through four subtypes (α1, α2, α3 and α5) of GABAA receptors (GABAAR). When applied to the spinal cord, they alleviate pathological pain; however, insufficient efficacy after systemic administration and undesired effects preclude their use in routine pain therapy. Previous work suggested that subtype-selective drugs might allow separating desired antihyperalgesia from unwanted effects, but the lack of selective agents has hitherto prevented systematic analyses. Here we use four lines of triple GABAAR point-mutated mice, which express only one benzodiazepine-sensitive GABAAR subtype at a time, to show that targeting only α2GABAARs achieves strong antihyperalgesia and reduced side effects (that is, no sedation, motor impairment and tolerance development). Additional pharmacokinetic and pharmacodynamic analyses in these mice explain why clinically relevant antihyperalgesia cannot be achieved with nonselective BDZs. These findings should foster the development of innovative subtype-selective BDZs for novel indications such as chronic pain. Benzodiazepines (BDZs) target GABAA receptors to alleviate pain but these also cause side effects. Here the authors use mice in which only one GABAA receptor is BDZ-sensitive at a time to identify α2GABAA as the receptor that provides maximal analgesic activity but minimal side-effects in response to BDZs.
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Affiliation(s)
- William T Ralvenius
- 1] Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland [2] Center for Neuroscience Zurich (ZNZ), Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Dietmar Benke
- 1] Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland [2] Center for Neuroscience Zurich (ZNZ), Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Mario A Acuña
- 1] Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland [2] Center for Neuroscience Zurich (ZNZ), Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Uwe Rudolph
- 1] Laboratory of Genetic Neuropharmacology, McLean Hospital, 115 Mill Street, Belmont, Massachusetts 02478, USA [2] Department of Psychiatry, Harvard Medical School, 401 Park Drive, Boston, Massachusetts 02215, USA
| | - Hanns Ulrich Zeilhofer
- 1] Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland [2] Center for Neuroscience Zurich (ZNZ), Winterthurerstrasse 190, CH-8057 Zurich, Switzerland [3] Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology (ETH) Zurich, Vladimir-Prelog-Weg 4, CH-8093 Zurich, Switzerland
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Besse A, Wu P, Bruni F, Donti T, Graham BH, Craigen WJ, McFarland R, Moretti P, Lalani S, Scott KL, Taylor RW, Bonnen PE. The GABA transaminase, ABAT, is essential for mitochondrial nucleoside metabolism. Cell Metab 2015; 21:417-27. [PMID: 25738457 PMCID: PMC4757431 DOI: 10.1016/j.cmet.2015.02.008] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 12/18/2014] [Accepted: 02/06/2015] [Indexed: 01/12/2023]
Abstract
ABAT is a key enzyme responsible for catabolism of principal inhibitory neurotransmitter γ-aminobutyric acid (GABA). We report an essential role for ABAT in a seemingly unrelated pathway, mitochondrial nucleoside salvage, and demonstrate that mutations in this enzyme cause an autosomal recessive neurometabolic disorder and mtDNA depletion syndrome (MDS). We describe a family with encephalomyopathic MDS caused by a homozygous missense mutation in ABAT that results in elevated GABA in subjects' brains as well as decreased mtDNA levels in subjects' fibroblasts. Nucleoside rescue and co-IP experiments pinpoint that ABAT functions in the mitochondrial nucleoside salvage pathway to facilitate conversion of dNDPs to dNTPs. Pharmacological inhibition of ABAT through the irreversible inhibitor Vigabatrin caused depletion of mtDNA in photoreceptor cells that was prevented through addition of dNTPs in cell culture media. This work reveals ABAT as a connection between GABA metabolism and nucleoside metabolism and defines a neurometabolic disorder that includes MDS.
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Affiliation(s)
- Arnaud Besse
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Ping Wu
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Francesco Bruni
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Taraka Donti
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Brett H Graham
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - William J Craigen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Robert McFarland
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Paolo Moretti
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Seema Lalani
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Kenneth L Scott
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Robert W Taylor
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Penelope E Bonnen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA.
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215
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Brady ML, Jacob TC. Synaptic localization of α5 GABA (A) receptors via gephyrin interaction regulates dendritic outgrowth and spine maturation. Dev Neurobiol 2015; 75:1241-51. [PMID: 25663431 DOI: 10.1002/dneu.22280] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Revised: 02/04/2015] [Accepted: 02/04/2015] [Indexed: 11/08/2022]
Abstract
GABAA receptor subunit composition is a critical determinant of receptor localization and physiology, with synaptic receptors generating phasic inhibition and extrasynaptic receptors producing tonic inhibition. Extrasynaptically localized α5 GABAA receptors are largely responsible for tonic inhibition in hippocampal neurons. However, we show here that inhibitory synapses also contain a constant level of α5 GABAA receptors throughout neuronal development, as measured by its colocalization with gephyrin, the inhibitory postsynaptic scaffolding protein. Immunoprecipitation of the α5 subunit from both cultured neurons and adult rat brain coimmunoprecipitated gephyrin, confirming this interaction in vivo. Furthermore, the α5 subunit can interact with gephyrin independent of other synaptically localized alpha subunits, as shown by immunoprecipitation experiments in HEK cells. By replacing the α5 predicted gephyrin binding domain (Residues 370-385) with either the high affinity gephyrin binding domain of the α2 subunit or homologous residues from the extrasynaptic α4 subunit that does not interact with gephyrin, α5 GABAA receptor localization shifted into or out of the synapse, respectively. These shifts in the ratio of synaptic/extrasynaptic α5 localization disrupted dendritic outgrowth and spine maturation. In contrast to the predominant view of α5 GABAA receptors being extrasynaptic and modulating tonic inhibition, we identify an intimate association of the α5 subunit with gephyrin, resulting in constant synaptic levels of α5 GABAA R throughout circuit formation that regulates neuronal development.
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Affiliation(s)
- Megan L Brady
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, 15261
| | - Tija C Jacob
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, 15261
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216
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Wang HG, Jeffries JJ, Wang TF. Genetic and Developmental Perspective of Language Abnormality in Autism and Schizophrenia. Neuroscientist 2015; 22:119-31. [DOI: 10.1177/1073858415572078] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Language and communication through it are two of the defining features of normally developed human beings. However, both these functions are often impaired in autism and schizophrenia. In the former disorder, the problem usually emerges in early childhood (~2 years old) and typically includes a lack of communication. In the latter condition, the language problems usually occur in adolescence and adulthood and presents as disorganized speech. What are the fundamental mechanisms underlying these two disorders? Is there a shared genetic basis? Are the traditional beliefs about them true? Are there any common strategies for their prevention and management? To answer these questions, we searched PubMed by using autism, schizophrenia, gene, and language abnormality as keywords, and we reconsidered the basic concepts about these two diseases or syndromes. We found many functional genes, for example, FOXP2, COMT, GABRB3, and DISC1, are actually implicated in both of them. After observing the symptoms, genetic correlates, and temporal progression of these two disorders as well as their relationships more carefully, we now infer that the occurrence of these two diseases is likely developmentally regulated via interaction between the genome and the environment. Furthermore, we propose a unified view of autism and schizophrenia: a single age-dependently occurred disease that is newly named as Systemic Integral Disorder: if occurring in children before age 2, it is called autism; if in adolescence or a later age, it is called schizophrenia.
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Affiliation(s)
- Haoran George Wang
- Department of Psychology, University of Toronto, Toronto, Ontario, Canada
- Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
- Centre for Addiction and Mental Health, Toronto, Ontario, Canada
| | - Joseph Joel Jeffries
- Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
- Centre for Addiction and Mental Health, Toronto, Ontario, Canada
| | - Tianren Frank Wang
- Department of Molecular Genetics, Mount Sinai Hospital, Toronto, Ontario, Canada
- Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
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217
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Olsen RW. Allosteric ligands and their binding sites define γ-aminobutyric acid (GABA) type A receptor subtypes. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2015; 73:167-202. [PMID: 25637441 DOI: 10.1016/bs.apha.2014.11.005] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
GABAA receptors (GABA(A)Rs) mediate rapid inhibitory transmission in the brain. GABA(A)Rs are ligand-gated chloride ion channel proteins and exist in about a dozen or more heteropentameric subtypes exhibiting variable age and brain regional localization and thus participation in differing brain functions and diseases. GABA(A)Rs are also subject to modulation by several chemotypes of allosteric ligands that help define structure and function, including subtype definition. The channel blocker picrotoxin identified a noncompetitive channel blocker site in GABA(A)Rs. This ligand site is located in the transmembrane channel pore, whereas the GABA agonist site is in the extracellular domain at subunit interfaces, a site useful for low energy coupled conformational changes of the functional channel domain. Two classes of pharmacologically important allosteric modulatory ligand binding sites reside in the extracellular domain at modified agonist sites at other subunit interfaces: the benzodiazepine site and the high-affinity, relevant to intoxication, ethanol site. The benzodiazepine site is specific for certain GABA(A)R subtypes, mainly synaptic, while the ethanol site is found at a modified benzodiazepine site on different, extrasynaptic, subtypes. In the transmembrane domain are allosteric modulatory ligand sites for diverse chemotypes of general anesthetics: the volatile and intravenous agents, barbiturates, etomidate, propofol, long-chain alcohols, and neurosteroids. The last are endogenous positive allosteric modulators. X-ray crystal structures of prokaryotic and invertebrate pentameric ligand-gated ion channels, and the mammalian GABA(A)R protein, allow homology modeling of GABA(A)R subtypes with the various ligand sites located to suggest the structure and function of these proteins and their pharmacological modulation.
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Affiliation(s)
- Richard W Olsen
- Department of Molecular & Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.
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218
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Luscher B, Fuchs T. GABAergic control of depression-related brain states. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2015; 73:97-144. [PMID: 25637439 DOI: 10.1016/bs.apha.2014.11.003] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The GABAergic deficit hypothesis of major depressive disorders (MDDs) posits that reduced γ-aminobutyric acid (GABA) concentration in brain, impaired function of GABAergic interneurons, altered expression and function of GABA(A) receptors, and changes in GABAergic transmission dictated by altered chloride homeostasis can contribute to the etiology of MDD. Conversely, the hypothesis posits that the efficacy of currently used antidepressants is determined by their ability to enhance GABAergic neurotransmission. We here provide an update for corresponding evidence from studies of patients and preclinical animal models of depression. In addition, we propose an explanation for the continued lack of genetic evidence that explains the considerable heritability of MDD. Lastly, we discuss how alterations in GABAergic transmission are integral to other hypotheses of MDD that emphasize (i) the role of monoaminergic deficits, (ii) stress-based etiologies, (iii) neurotrophic deficits, and (iv) the neurotoxic and neural circuit-impairing consequences of chronic excesses of glutamate. We propose that altered GABAergic transmission serves as a common denominator of MDD that can account for all these other hypotheses and that plays a causal and common role in diverse mechanistic etiologies of depressive brain states and in the mechanism of action of current antidepressant drug therapies.
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Affiliation(s)
- Bernhard Luscher
- Department of Biology, The Pennsylvania State University, University Park, Pennsylvania, USA; Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, USA; Center for Molecular Investigation of Neurological Disorders, The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania, USA.
| | - Thomas Fuchs
- Department of Biology, The Pennsylvania State University, University Park, Pennsylvania, USA; Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, USA; Center for Molecular Investigation of Neurological Disorders, The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania, USA
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219
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Wimmer L, Schönbauer D, Pakfeifer P, Schöffmann A, Khom S, Hering S, Mihovilovic MD. Developing piperine towards TRPV1 and GABAA receptor ligands – synthesis of piperine analogs via Heck-coupling of conjugated dienes. Org Biomol Chem 2015; 13:990-4. [DOI: 10.1039/c4ob02242d] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Synthetic analogs of piperine, the pungent alkaloid of black pepper, were identified as selective ligands for either GABAA or TRPV1 receptors.
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Affiliation(s)
- Laurin Wimmer
- Institute of Applied Synthetic Chemistry
- Vienna University of Technology
- 1060 Vienna
- Austria
| | - David Schönbauer
- Institute of Applied Synthetic Chemistry
- Vienna University of Technology
- 1060 Vienna
- Austria
| | - Peter Pakfeifer
- Department of Pharmacology and Toxicology
- University of Vienna
- 1090 Vienna
- Austria
| | - Angela Schöffmann
- Department of Pharmacology and Toxicology
- University of Vienna
- 1090 Vienna
- Austria
| | - Sophia Khom
- Department of Pharmacology and Toxicology
- University of Vienna
- 1090 Vienna
- Austria
| | - Steffen Hering
- Department of Pharmacology and Toxicology
- University of Vienna
- 1090 Vienna
- Austria
| | - Marko D. Mihovilovic
- Institute of Applied Synthetic Chemistry
- Vienna University of Technology
- 1060 Vienna
- Austria
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220
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GABAA receptor-acting neurosteroids: a role in the development and regulation of the stress response. Front Neuroendocrinol 2015; 36:28-48. [PMID: 24929099 PMCID: PMC4349499 DOI: 10.1016/j.yfrne.2014.06.001] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Revised: 05/26/2014] [Accepted: 06/01/2014] [Indexed: 12/22/2022]
Abstract
Regulation of hypothalamic-pituitary-adrenocortical (HPA) axis activity by stress is a fundamental survival mechanism and HPA-dysfunction is implicated in psychiatric disorders. Adverse early life experiences, e.g. poor maternal care, negatively influence brain development and programs an abnormal stress response by encoding long-lasting molecular changes, which may extend to the next generation. How HPA-dysfunction leads to the development of affective disorders is complex, but may involve GABAA receptors (GABAARs), as they curtail stress-induced HPA axis activation. Of particular interest are endogenous neurosteroids that potently modulate the function of GABAARs and exhibit stress-protective properties. Importantly, neurosteroid levels rise rapidly during acute stress, are perturbed in chronic stress and are implicated in the behavioural changes associated with early-life adversity. We will appraise how GABAAR-active neurosteroids may impact on HPA axis development and the orchestration of the stress-evoked response. The significance of these actions will be discussed in the context of stress-associated mood disorders.
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221
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Fritschy JM. Significance of GABAA Receptor Heterogeneity. DIVERSITY AND FUNCTIONS OF GABA RECEPTORS: A TRIBUTE TO HANNS MÖHLER, PART B 2015; 73:13-39. [DOI: 10.1016/bs.apha.2014.11.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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222
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Möhler H. The legacy of the benzodiazepine receptor: from flumazenil to enhancing cognition in Down syndrome and social interaction in autism. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2014; 72:1-36. [PMID: 25600365 DOI: 10.1016/bs.apha.2014.10.008] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The study of the psychopharmacology of benzodiazepines continues to provide new insights into diverse brain functions related to vigilance, anxiety, mood, epileptiform activity, schizophrenia, cognitive performance, and autism-related social behavior. In this endeavor, the discovery of the benzodiazepine receptor was a key event, as it supplied the primary benzodiazepine drug-target site, provided the molecular link to the allosteric modulation of GABAA receptors and, following the recognition of GABAA receptor subtypes, furnished the platform for future, more selective drug actions. This review has two parts. In a retrospective first part, it acknowledges the contributions to the field made by my collaborators over the years, initially at Hoffmann-La Roche in Basle and later, in academia, at the University and the ETH of Zurich. In the second part, the new frontier of GABA pharmacology, targeting GABAA receptor subtypes, is reviewed with special focus on nonsedative anxiolytics, antidepressants, analgesics, as well as enhancers of cognition in Down syndrome and attenuators of symptoms of autism spectrum disorders. It is encouraging that a clinical trial has been initiated with a partial inverse agonist acting on α5 GABAA receptors in an attempt to alleviate the cognitive deficits in Down syndrome.
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Affiliation(s)
- Hanns Möhler
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland; Department of Chemistry and Applied Biosciences, Federal Institute of Technology (ETH), Zurich, Switzerland.
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223
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Crestani F, Rudolph U. Behavioral functions of GABAA receptor subtypes--the Zurich experience. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2014; 72:37-51. [PMID: 25600366 DOI: 10.1016/bs.apha.2014.10.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
GABAA receptors are the major inhibitory neurotransmitter receptors in the brain. They are heteropentamers that are typically classified according to their α subunits. By rendering each of the benzodiazepine-sensitive α subunits (α1, α2, α3, and α5) insensitive to modulation by classical benzodiazepines by His to Arg point mutations in knock-in mice, we were able to identify behavioral functions mediated by different GABAA receptor subtypes, which led to the development of novel therapeutic strategies. In this chapter, we provide a largely chronological overview on behavioral studies on GABAA receptor mutant mice at the Institute of Pharmacology and Toxicology at the University of Zurich.
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Affiliation(s)
- Florence Crestani
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
| | - Uwe Rudolph
- Laboratory of Genetic Neuropharmacology, McLean Hospital, Belmont, Massachusetts, USA; Department of Psychiatry, Harvard Medical School, Boston, Massachusetts, USA.
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224
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Sieghart W. Allosteric modulation of GABAA receptors via multiple drug-binding sites. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2014; 72:53-96. [PMID: 25600367 DOI: 10.1016/bs.apha.2014.10.002] [Citation(s) in RCA: 135] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
GABAA receptors are ligand-gated ion channels composed of five subunits that can be opened by GABA and be modulated by multiple pharmacologically and clinically important drugs. Over the time, hundreds of compounds from different structural classes have been demonstrated to modulate, directly activate, or inhibit GABAA receptors, and most of these compounds interact with more than one binding site at these receptors. Crystal structures of proteins and receptors homologous to GABAA receptors as well as homology modeling studies have provided insights into the possible location of ligand interaction sites. Some of these sites have been identified by mutagenesis, photolabeling, and docking studies. For most of these ligands, however, binding sites are not known. Due to the high flexibility of GABAA receptors and the existence of multiple drug-binding sites, the unequivocal identification of interaction sites for individual drugs is extremely difficult. The existence of multiple GABAA receptor subtypes with distinct subunit composition, the contribution of distinct subunit sequences to binding sites of different receptor subtypes, as well as the observation that even subunits not directly contributing to a binding site are able to influence affinity and efficacy of drugs, contribute to a unique pharmacology of each GABAA receptor subtype. Thus, each receptor subtype has to be investigated to identify a possible subtype selectivity of a compound. Although multiple binding sites make GABAA receptor pharmacology even more complicated, the exploitation of ligand interaction with novel-binding sites also offers additional possibilities for a subtype-selective modulation of GABAA receptors.
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Affiliation(s)
- Werner Sieghart
- Department of Molecular Neurosciences, Center for Brain Research, Medical University Vienna, Vienna, Austria.
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225
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Brown AR, Herd MB, Belelli D, Lambert JJ. Developmentally regulated neurosteroid synthesis enhances GABAergic neurotransmission in mouse thalamocortical neurones. J Physiol 2014; 593:267-84. [PMID: 25556800 DOI: 10.1113/jphysiol.2014.280263] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Accepted: 10/25/2014] [Indexed: 12/12/2022] Open
Abstract
KEY POINTS During neuronal development synaptic events mediated by GABAA receptors are progressively reduced in their duration, allowing for rapid and precise network function. Here we focused on ventrobasal thalamocortical neurones, which contribute to behaviourally relevant oscillations between thalamus and cortex. We demonstrate that the developmental decrease in the duration of inhibitory phasic events results predominantly from a precisely timed loss of locally produced neurosteroids, which act as positive allosteric modulators of the GABAA receptor. The mature thalamus retains the ability to synthesise neurosteroids, thus preserving the capacity to enhance both phasic and tonic inhibition, mediated by synaptic and extrasynaptic GABAA receptors, respectively, in physiological and pathophysiological scenarios associated with perturbed neurosteroid levels. Our data establish a potent, endogenous mechanism to locally regulate the GABAA receptor function and thereby influence thalamocortical activity. During brain development the duration of miniature inhibitory postsynaptic currents (mIPSCs) mediated by GABAA receptors (GABAA Rs) progressively reduces, to accommodate the temporal demands required for precise network activity. Conventionally, this synaptic plasticity results from GABAA R subunit reorganisation. In particular, in certain developing neurones synaptic α2-GABAA Rs are replaced by α1-GABAA Rs. However, in thalamocortical neurones of the mouse ventrobasal (VB) thalamus, the major alteration to mIPSC kinetics occurs on postnatal (P) day 10, some days prior to the GABAA R isoform change. Here, whole-cell voltage-clamp recordings from VB neurones of mouse thalamic slices revealed that early in postnatal development (P7-P8), the mIPSC duration is prolonged by local neurosteroids acting in a paracrine or autocrine manner to enhance GABAA R function. However, by P10, this neurosteroid 'tone' rapidly dissipates, thereby producing brief mIPSCs. This plasticity results from a lack of steroid substrate as pre-treatment of mature thalamic slices (P20-24) with the GABAA R-inactive precursor 5α-dihydroprogesterone (5α-DHP) resulted in markedly prolonged mIPSCs and a greatly enhanced tonic conductance, mediated by synaptic and extrasynaptic GABAA Rs, respectively. In summary, endogenous neurosteroids profoundly influence GABAergic neurotransmission in developing VB neurones and govern a transition from slow to fast phasic synaptic events. Furthermore, the retained capacity for steroidogenesis in the mature thalamus raises the prospect that certain physiological or pathophysiological conditions may trigger neurosteroid neosynthesis, thereby providing a local mechanism for fine-tuning neuronal excitability.
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Affiliation(s)
- Adam R Brown
- Division of Neuroscience, Medical Research Institute, Ninewells Hospital and Medical School, Dundee University, Dundee, DD1 9SY, UK
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226
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Ding J, Huang C, Peng Z, Xie Y, Deng S, Nie YZ, Xu TL, Ge WH, Li WG, Li F. Electrophysiological characterization of methyleugenol: a novel agonist of GABA(A) receptors. ACS Chem Neurosci 2014; 5:803-11. [PMID: 24980777 DOI: 10.1021/cn500022e] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Methyleugenol (ME) is a natural constituent isolated from many plant essential oils having multiple biological effects including anticonvulsant and anesthetic activities, although the underlying mechanisms remain unclear. Here, we identify ME as a novel agonist of ionotropic γ-aminobutyric acid (GABA) receptors. At lower concentrations (∼30 μM), ME significantly sensitized GABA-induced, but not glutamate- or glycine-induced, currents in cultured hippocampal neurons, indicative of a preferentially modulatory role of this compound for A type GABA receptors (GABAARs). In addition, ME at higher concentrations (≥100 μM) induced a concentration-dependent, Cl(-)-permeable current in hippocampal neurons, which was inhibited by a GABAAR channel blocker, picrotoxin, and a competitive GABAAR antagonist, bicuculline, but not a specific glycine receptor inhibitor, strychnine. Moreover, ME activated a similar current mediated by recombinant α1-β2-γ2 or α5-β2-γ2 GABAARs in human embryonic kidney (HEK) cells. Consequently, ME produced a strong inhibition of synaptically driven neuronal excitation in hippocampal neurons. Together, these results suggest that ME represents a novel agonist of GABAARs, shedding additional light on future development of new therapeutics targeting GABAARs. The present study also adds GABAAR activation to the list of molecular targets of ME that probably account for its biological activities.
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Affiliation(s)
- Jing Ding
- Department
of Developmental and Behavioral Pediatrics, Shanghai Institute of
Pediatric Translational Medicine, Shanghai Children’s Medical
Center, Ministry of Education-Shanghai Key Laboratory of Children’s
Environmental Health, Shanghai Jiao Tong University School of Medicine, Shanghai 200129, China
- Department
of Chinese Materia Medica, College of Pharmaceutical Science, Zhejiang Chinese Medical University, Hangzhou 310053, China
- Neuroscience
Division, Departments of Anatomy, Histology and Embryology, Biochemistry,
and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment
and Inflammation, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Chen Huang
- Neuroscience
Division, Departments of Anatomy, Histology and Embryology, Biochemistry,
and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment
and Inflammation, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Zhong Peng
- Neuroscience
Division, Departments of Anatomy, Histology and Embryology, Biochemistry,
and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment
and Inflammation, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Yuxuan Xie
- Department
of Developmental and Behavioral Pediatrics, Shanghai Institute of
Pediatric Translational Medicine, Shanghai Children’s Medical
Center, Ministry of Education-Shanghai Key Laboratory of Children’s
Environmental Health, Shanghai Jiao Tong University School of Medicine, Shanghai 200129, China
| | - Shining Deng
- Department
of Developmental and Behavioral Pediatrics, Shanghai Institute of
Pediatric Translational Medicine, Shanghai Children’s Medical
Center, Ministry of Education-Shanghai Key Laboratory of Children’s
Environmental Health, Shanghai Jiao Tong University School of Medicine, Shanghai 200129, China
| | - Yan-Zhen Nie
- Department
of Developmental and Behavioral Pediatrics, Shanghai Institute of
Pediatric Translational Medicine, Shanghai Children’s Medical
Center, Ministry of Education-Shanghai Key Laboratory of Children’s
Environmental Health, Shanghai Jiao Tong University School of Medicine, Shanghai 200129, China
| | - Tian-Le Xu
- Neuroscience
Division, Departments of Anatomy, Histology and Embryology, Biochemistry,
and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment
and Inflammation, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Wei-Hong Ge
- Department
of Chinese Materia Medica, College of Pharmaceutical Science, Zhejiang Chinese Medical University, Hangzhou 310053, China
| | - Wei-Guang Li
- Department
of Developmental and Behavioral Pediatrics, Shanghai Institute of
Pediatric Translational Medicine, Shanghai Children’s Medical
Center, Ministry of Education-Shanghai Key Laboratory of Children’s
Environmental Health, Shanghai Jiao Tong University School of Medicine, Shanghai 200129, China
- Neuroscience
Division, Departments of Anatomy, Histology and Embryology, Biochemistry,
and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment
and Inflammation, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Fei Li
- Department
of Developmental and Behavioral Pediatrics, Shanghai Institute of
Pediatric Translational Medicine, Shanghai Children’s Medical
Center, Ministry of Education-Shanghai Key Laboratory of Children’s
Environmental Health, Shanghai Jiao Tong University School of Medicine, Shanghai 200129, China
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227
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Olsen RW. Analysis of γ-aminobutyric acid (GABA) type A receptor subtypes using isosteric and allosteric ligands. Neurochem Res 2014; 39:1924-41. [PMID: 25015397 DOI: 10.1007/s11064-014-1382-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Revised: 06/30/2014] [Accepted: 07/02/2014] [Indexed: 11/30/2022]
Abstract
The GABAA receptors (GABAARs) play an important role in inhibitory transmission in the brain. The GABAARs could be identified using a medicinal chemistry approach to characterize with a series of chemical structural analogues, some identified in nature, some synthesized, to control the structural conformational rigidity/flexibility so as to define the 'receptor-specific' GABA agonist ligand structure. In addition to the isosteric site ligands, these ligand-gated chloride ion channel proteins exhibited modulation by several chemotypes of allosteric ligands, that help define structure and function. The channel blocker picrotoxin identified a noncompetitive channel blocker site in GABAARs. This ligand site is located in the transmembrane channel pore, whereas the GABA agonist site is in the extracellular domain at subunit interfaces, a site useful for low energy coupled conformational changes of the functional channel domain. Also in the trans-membrane domain are allosteric modulatory ligand sites, mostly positive, for diverse chemotypes with general anesthetic efficacy, namely, the volatile and intravenous agents: barbiturates, etomidate, propofol, long-chain alcohols, and neurosteroids. The last are apparent endogenous positive allosteric modulators of GABAARs. These binding sites depend on the GABAAR heteropentameric subunit composition, i.e., subtypes. Two classes of pharmacologically very important allosteric modulatory ligand binding site reside in the extracellular domain at modified agonist sites at other subunit interfaces: the benzodiazepine site, and the low-dose ethanol site. The benzodiazepine site is specific for certain subunit combination subtypes, mainly synaptically localized. In contrast, the low-dose (high affinity) ethanol site(s) is found at a modified benzodiazepine site on different, extrasynaptic, subtypes.
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Affiliation(s)
- Richard W Olsen
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Room CHS 23-120, 650 Young Drive South, Los Angeles, CA, 90095-1735, USA,
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Abstract
The neurotransmitters GABA and glycine mediate fast synaptic inhibition by activating ligand-gated chloride channels--namely, type A GABA (GABA(A)) and glycine receptors. Both types of receptors are anchored postsynaptically by gephyrin, which self-assembles into a scaffold and interacts with the cytoskeleton. Current research indicates that postsynaptic gephyrin clusters are dynamic assemblies that are held together and regulated by multiple protein-protein interactions. Moreover, post-translational modifications of gephyrin regulate the formation and plasticity of GABAergic synapses by altering the clustering properties of postsynaptic scaffolds and thereby the availability and function of receptors and other signalling molecules. Here, we discuss the formation and regulation of the gephyrin scaffold, its role in GABAergic and glycinergic synaptic function and the implications for the pathophysiology of brain disorders caused by abnormal inhibitory neurotransmission.
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229
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Pla P, Orvoen S, Saudou F, David DJ, Humbert S. Mood disorders in Huntington's disease: from behavior to cellular and molecular mechanisms. Front Behav Neurosci 2014; 8:135. [PMID: 24795586 PMCID: PMC4005937 DOI: 10.3389/fnbeh.2014.00135] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Accepted: 04/03/2014] [Indexed: 01/29/2023] Open
Abstract
Huntington's disease (HD) is a neurodegenerative disorder that is best known for its effect on motor control. Mood disturbances such as depression, anxiety, and irritability also have a high prevalence in patients with HD, and often start before the onset of motor symptoms. Various rodent models of HD recapitulate the anxiety/depressive behavior seen in patients. HD is caused by an expanded polyglutamine stretch in the N-terminal part of a 350 kDa protein called huntingtin (HTT). HTT is ubiquitously expressed and is implicated in several cellular functions including control of transcription, vesicular trafficking, ciliogenesis, and mitosis. This review summarizes progress in efforts to understand the cellular and molecular mechanisms underlying behavioral disorders in patients with HD. Dysfunctional HTT affects cellular pathways that are involved in mood disorders or in the response to antidepressants, including BDNF/TrkB and serotonergic signaling. Moreover, HTT affects adult hippocampal neurogenesis, a physiological phenomenon that is implicated in some of the behavioral effects of antidepressants and is linked to the control of anxiety. These findings are consistent with the emerging role of wild-type HTT as a crucial component of neuronal development and physiology. Thus, the pathogenic polyQ expansion in HTT could lead to mood disorders not only by the gain of a new toxic function but also by the perturbation of its normal function.
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Affiliation(s)
- Patrick Pla
- Institut Curie Orsay, France ; CNRS UMR3306 Orsay, France ; INSERM U1005 Orsay, France ; Faculté des Sciences, Université Paris-Sud Orsay, France
| | - Sophie Orvoen
- EA3544, Faculté de Pharmacie, Université Paris-Sud Châtenay-Malabry, France
| | - Frédéric Saudou
- Institut Curie Orsay, France ; CNRS UMR3306 Orsay, France ; INSERM U1005 Orsay, France
| | - Denis J David
- EA3544, Faculté de Pharmacie, Université Paris-Sud Châtenay-Malabry, France
| | - Sandrine Humbert
- Institut Curie Orsay, France ; CNRS UMR3306 Orsay, France ; INSERM U1005 Orsay, France
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230
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Möhler H. Endogenous Benzodiazepine Site Peptide Ligands Operating Bidirectionally In Vivo in Neurogenesis and Thalamic Oscillations. Neurochem Res 2014; 39:1032-6. [DOI: 10.1007/s11064-014-1303-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Revised: 03/31/2014] [Accepted: 04/01/2014] [Indexed: 01/25/2023]
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231
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Dihydromyricetin prevents fetal alcohol exposure-induced behavioral and physiological deficits: the roles of GABAA receptors in adolescence. Neurochem Res 2014; 39:1147-61. [PMID: 24676702 DOI: 10.1007/s11064-014-1291-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Revised: 03/18/2014] [Accepted: 03/20/2014] [Indexed: 10/25/2022]
Abstract
Fetal alcohol exposure (FAE) can lead to a variety of behavioral and physiological disturbances later in life. Understanding how alcohol (ethanol, EtOH) affects fetal brain development is essential to guide the development of better therapeutics for FAE. One of EtOH's many pharmacological targets is the γ-aminobutyric acid type A receptor (GABAAR), which plays a prominent role in early brain development. Acute EtOH potentiates inhibitory currents carried by certain GABAAR subtypes, whereas chronic EtOH leads to persistent alterations in GABAAR subunit composition, localization and function. We recently introduced a flavonoid compound, dihydromyricetin (DHM), which selectively antagonizes EtOH's intoxicating effects in vivo and in vitro at enhancing GABAAR function as a candidate for alcohol abuse pharmacotherapy. Here, we studied the effect of FAE on physiology, behavior and GABAAR function of early adolescent rats and tested the utility of DHM as a preventative treatment for FAE-induced disturbances. Gavage administration of EtOH (1.5, 2.5, or 5.0 g/kg) to rat dams on day 5, 8, 10, 12, and 15 of pregnancy dose-dependently reduced female/male offspring ratios (largely through decreased numbers of female offspring) and offspring body weights. FAE (2.5 g/kg) rats tested on postnatal days (P) 25-32 also exhibited increased anxiety and reduced pentylenetetrazol (PTZ)-induced seizure threshold. Patch-clamp recordings from dentate gyrus granule cells (DGCs) in hippocampal slices from FAE (2.5 g/kg) rats at P25-35 revealed reduced sensitivity of GABAergic miniature inhibitory postsynaptic currents (mIPSCs) and tonic current (Itonic) to potentiation by zolpidem (0.3 μM). Interestingly, potentiation of mIPSCs by gaboxadol increased, while potentiation of Itonic decreased in DGCs from FAE rats. Co-administration of EtOH (1.5 or 2.5 g/kg) with DHM (1.0 mg/kg) in pregnant dams prevented all of the behavioral, physiological, and pharmacological alterations observed in FAE offspring. DHM administration alone in pregnant rats had no adverse effect on litter size, progeny weight, anxiety level, PTZ seizure threshold, or DGC GABAAR function. Our results indicate that FAE induces long-lasting alterations in physiology, behavior, and hippocampal GABAAR function and that these deficits are prevented by DHM co-treatment of EtOH-exposed dams. The absence of adverse side effects and the ability of DHM to prevent FAE consequences suggest that DHM is an attractive candidate for development as a treatment for prevention of fetal alcohol spectrum disorders.
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Fritschy JM, Panzanelli P. GABAAreceptors and plasticity of inhibitory neurotransmission in the central nervous system. Eur J Neurosci 2014; 39:1845-65. [DOI: 10.1111/ejn.12534] [Citation(s) in RCA: 144] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2014] [Revised: 01/29/2014] [Accepted: 01/29/2014] [Indexed: 12/11/2022]
Affiliation(s)
- Jean-Marc Fritschy
- Institute of Pharmacology and Toxicology; University of Zurich; Winterthurerstrasse 190 8057 Zurich Switzerland
- Neuroscience Center Zurich; University of Zurich and ETH; Zurich Switzerland
| | - Patrizia Panzanelli
- Department of Neuroscience Rita Levi Montalcini; University of Turin; Turin Italy
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Signal Transduction in Astrocytes during Chronic or Acute Treatment with Drugs (SSRIs, Antibipolar Drugs, GABA-ergic Drugs, and Benzodiazepines) Ameliorating Mood Disorders. JOURNAL OF SIGNAL TRANSDUCTION 2014; 2014:593934. [PMID: 24707399 PMCID: PMC3953578 DOI: 10.1155/2014/593934] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Accepted: 12/16/2013] [Indexed: 01/29/2023]
Abstract
Chronic treatment with fluoxetine or other so-called serotonin-specific reuptake inhibitor antidepressants (SSRIs) or with a lithium salt “lithium”, carbamazepine, or valproic acid, the three classical antibipolar drugs, exerts a multitude of effects on astrocytes, which in turn modulate astrocyte-neuronal interactions and brain function. In the case of the SSRIs, they are to a large extent due to 5-HT2B-mediated upregulation and editing of genes. These alterations induce alteration in effects of cPLA2, GluK2, and the 5-HT2B receptor, probably including increases in both glucose metabolism and glycogen turnover, which in combination have therapeutic effect on major depression. The ability of increased levels of extracellular K+ to increase [Ca2+]i is increased as a sign of increased K+-induced excitability in astrocytes. Acute anxiolytic drug treatment with benzodiazepines or GABAA receptor stimulation has similar glycogenolysis-enhancing effects. The antibipolar drugs induce intracellular alkalinization in astrocytes with lithium acting on one acid extruder and carbamazepine and valproic acid on a different acid extruder. They inhibit K+-induced and transmitter-induced increase of astrocytic [Ca2+]i and thereby probably excitability. In several cases, they exert different changes in gene expression than SSRIs, determined both in cultured astrocytes and in freshly isolated astrocytes from drug-treated animals.
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234
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Ding J, Wang JJ, Huang C, Wang L, Deng S, Xu TL, Ge WH, Li WG, Li F. Curcumol from Rhizoma Curcumae suppresses epileptic seizure by facilitation of GABA(A) receptors. Neuropharmacology 2014; 81:244-55. [PMID: 24565642 DOI: 10.1016/j.neuropharm.2014.02.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Revised: 02/10/2014] [Accepted: 02/13/2014] [Indexed: 10/25/2022]
Abstract
Rhizoma Curcumae is a common Chinese dietary spice used in South Asia and China for thousands of years. As the main extract, Rhizoma Curcumae oil has attracted a great interest due to its newly raised therapeutic activities including its pharmacological effects upon central nervous system such as neuroprotection, cognitive enhancement, and anti-seizure efficacy; however the molecular mechanisms and the target identification remain to be established. Here we characterize an inhibitory effect of curcumol, a major bioactive component of Rhizoma Curcumae oil, on the excitability of hippocampal neurons in culture, the basal locomotor activity of freely moving animals, and the chemically induced seizure activity in vivo. Electrophysiological recording showed that acute application of curcumol significantly facilitated the γ-aminobutyric acid (GABA)-activated current in cultured mouse hippocampal neurons and in human embryonic kidney cells expressing α1- or α5-containing A type GABA (GABAA) receptors in a concentration-dependent manner. Measurement of tonic and miniature inhibitory postsynaptic GABAergic currents in hippocampal slices indicated that curcumol enhanced both forms of inhibition. In both pentylenetetrazole and kainate seizure models, curcumol suppressed epileptic activity in mice by prolonging the latency to clonic and tonic seizures and reducing the mortality as well as the susceptibility to seizure, presumably by facilitating the activation of GABAA receptors. Taken together, our results identified curcumol as a novel anti-seizure agent which inhibited neuronal excitability through enhancing GABAergic inhibition.
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Affiliation(s)
- Jing Ding
- Department of Chinese Materia Medica, College of Pharmaceutical Science, Zhejiang Chinese Medical University, Hangzhou 310053, China; Department of Developmental and Behavioral Pediatrics, Shanghai Institute of Pediatric Translational Medicine, Shanghai Children's Medical Center, Ministry of Education-Shanghai Key Laboratory of Children's Environmental Health, Shanghai Jiao Tong University School of Medicine, Shanghai 200129, China; Departments of Anatomy and Embryology, Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Jing-Jing Wang
- Departments of Anatomy and Embryology, Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Chen Huang
- Departments of Anatomy and Embryology, Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Li Wang
- Departments of Anatomy and Embryology, Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Shining Deng
- Department of Developmental and Behavioral Pediatrics, Shanghai Institute of Pediatric Translational Medicine, Shanghai Children's Medical Center, Ministry of Education-Shanghai Key Laboratory of Children's Environmental Health, Shanghai Jiao Tong University School of Medicine, Shanghai 200129, China
| | - Tian-Le Xu
- Departments of Anatomy and Embryology, Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Wei-Hong Ge
- Department of Chinese Materia Medica, College of Pharmaceutical Science, Zhejiang Chinese Medical University, Hangzhou 310053, China
| | - Wei-Guang Li
- Department of Developmental and Behavioral Pediatrics, Shanghai Institute of Pediatric Translational Medicine, Shanghai Children's Medical Center, Ministry of Education-Shanghai Key Laboratory of Children's Environmental Health, Shanghai Jiao Tong University School of Medicine, Shanghai 200129, China; Departments of Anatomy and Embryology, Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China.
| | - Fei Li
- Department of Developmental and Behavioral Pediatrics, Shanghai Institute of Pediatric Translational Medicine, Shanghai Children's Medical Center, Ministry of Education-Shanghai Key Laboratory of Children's Environmental Health, Shanghai Jiao Tong University School of Medicine, Shanghai 200129, China.
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