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Marron Fernandez de Velasco E, Tipps ME, Haider B, Souders A, Aguado C, Rose TR, Vo BN, DeBaker MC, Luján R, Wickman K. Ethanol-Induced Suppression of G Protein-Gated Inwardly Rectifying K +-Dependent Signaling in the Basal Amygdala. Biol Psychiatry 2023; 94:863-874. [PMID: 37068702 PMCID: PMC10576835 DOI: 10.1016/j.biopsych.2023.04.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 04/05/2023] [Accepted: 04/05/2023] [Indexed: 04/19/2023]
Abstract
BACKGROUND The basolateral amygdala (BLA) regulates mood and associative learning and has been linked to the development and persistence of alcohol use disorder. The GABABR (gamma-aminobutyric acid B receptor) is a promising therapeutic target for alcohol use disorder, and previous work suggests that exposure to ethanol and other drugs can alter neuronal GABABR-dependent signaling. The effect of ethanol on GABABR-dependent signaling in the BLA is unknown. METHODS GABABR-dependent signaling in the mouse BLA was examined using slice electrophysiology following repeated ethanol exposure. Neuron-specific viral genetic manipulations were then used to understand the relevance of ethanol-induced neuroadaptations in the basal amygdala subregion (BA) to mood-related behavior. RESULTS The somatodendritic inhibitory effect of GABABR activation on principal neurons in the basal but not the lateral subregion of the BLA was diminished following ethanol exposure. This adaptation was attributable to the suppression of GIRK (G protein-gated inwardly rectifying K+) channel activity and was mirrored by a redistribution of GABABR and GIRK channels from the surface membrane to internal sites. While GIRK1 and GIRK2 subunits are critical for GIRK channel formation in BA principal neurons, GIRK3 is necessary for the ethanol-induced neuroadaptation. Viral suppression of GIRK channel activity in BA principal neurons from ethanol-naïve mice recapitulated some mood-related behaviors observed in C57BL/6J mice during ethanol withdrawal. CONCLUSIONS The ethanol-induced suppression of GIRK-dependent signaling in BA principal neurons contributes to some of the mood-related behaviors associated with ethanol withdrawal in mice. Approaches designed to prevent this neuroadaptation and/or strengthen GIRK-dependent signaling may prove useful for the treatment of alcohol use disorder.
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Affiliation(s)
| | - Megan E Tipps
- Department of Pharmacology, University of Minnesota, Minneapolis, Minnesota
| | - Bushra Haider
- Department of Pharmacology, University of Minnesota, Minneapolis, Minnesota
| | - Anna Souders
- Department of Pharmacology, University of Minnesota, Minneapolis, Minnesota
| | - Carolina Aguado
- Departmento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla La Mancha, Campus Biosanitario, La Mancha, Albacete, Spain
| | - Timothy R Rose
- Department of Pharmacology, University of Minnesota, Minneapolis, Minnesota
| | - Baovi N Vo
- Department of Pharmacology, University of Minnesota, Minneapolis, Minnesota
| | - Margot C DeBaker
- Graduate Program in Neuroscience, University of Minnesota, Minneapolis, Minnesota
| | - Rafael Luján
- Departmento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla La Mancha, Campus Biosanitario, La Mancha, Albacete, Spain
| | - Kevin Wickman
- Department of Pharmacology, University of Minnesota, Minneapolis, Minnesota
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Hwang Y, Park JH, Kim HC, Shin EJ. GABA B receptor activation alters astrocyte phenotype changes induced by trimethyltin via ERK signaling in the dentate gyrus of mice. Life Sci 2023; 319:121529. [PMID: 36841471 DOI: 10.1016/j.lfs.2023.121529] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Revised: 02/11/2023] [Accepted: 02/20/2023] [Indexed: 02/25/2023]
Abstract
AIMS We examined the effect of γ-aminobutyric acid (GABA)B receptor activation on astrocyte phenotype changes induced by trimethyltin (TMT) in the dentate gyrus of mice. MAIN METHODS Male C57BL/6N mice received TMT (2.6 mg/kg, i.p.), and the expression of GABAB receptors was evaluated in the hippocampus. The GABAB receptor agonist baclofen (2.5, 5, or 10 mg/kg, i.p. × 5 at 12-h intervals) was administered 3-5 days after TMT treatment, and the expression of Iba-1, GFAP, and astrocyte phenotype markers was evaluated 6 days after TMT. SL327 (30 mg/kg, i.p.), an extracellular signal-related kinase (ERK) inhibitor, was administered 1 h after each baclofen treatment. KEY FINDINGS TMT insult significantly induced the astroglial expression of GABAB receptors in the dentate molecular layer. Baclofen significantly promoted the expression of S100A10, EMP1, and CD109, but not that of C3, GGTA1, and MX1 induced by TMT. In addition, baclofen significantly increased the TMT-induced expression of p-ERK in the dentate molecular layer. Interestingly, p-ERK was more colocalized with S100A10 than with C3 after TMT insult, and a significant positive correlation was found between the expression of p-ERK and S100A10. Consistently, SL327 reversed the effect of baclofen on astrocyte phenotype changes. Baclofen also enhanced the TMT-induced astroglial expression of glial cell-derived neurotrophic factor (GDNF), an anti-inflammatory astrocytes-to-microglia mediator, and consequently attenuated Iba-1 expression and delayed apoptotic neuronal death. SIGNIFICANCE Our results suggest that GABAB receptor activation increases S100A10-positive anti-inflammatory astrocytes and astroglial GDNF expression via ERK signaling after TMT excitotoxicity in the dentate molecular layer of mice.
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Affiliation(s)
- Yeonggwang Hwang
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chuncheon 24341, Republic of Korea
| | - Jung Hoon Park
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chuncheon 24341, Republic of Korea
| | - Hyoung-Chun Kim
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chuncheon 24341, Republic of Korea.
| | - Eun-Joo Shin
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chuncheon 24341, Republic of Korea.
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Liu Q, Li Y, Shi Y, Tan J, Yan W, Zhang J, Gao P, Yan S. The protective effect of gamma aminobutyric acid B receptor activation on sympathetic nerve remodeling via the regulation of M2 macrophage polarization after myocardial infarction. Rev Port Cardiol 2023; 42:125-135. [PMID: 36759072 DOI: 10.1016/j.repc.2021.10.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 09/28/2021] [Accepted: 10/02/2021] [Indexed: 10/15/2022] Open
Abstract
INTRODUCTION & OBJECTIVES Acute myocardial infarction (AMI) in coronary heart disease is a leading cause of sudden death primarily due to malignant ventricular arrhythmias (VAs). Inflammatory cell infiltration and inflammation-induced overactivation of sympathetic nerves are the major cause of VAs in AMI pathophysiological processes. Type 2 macrophages play an anti-inflammatory role in AMI. Targeting macrophages may be a therapeutic strategy to prevent VAs post AMI. We found that gamma aminobutyric acid (GABA) promotes macrophages polarized to M2 and hypothesized that GABA might exert anti-inflammatory effects by promoting type 2 macrophage polarization in AMI. We aim to characterized GABAB receptor distribution, function, and mechanisms in M2 macrophage polarization and explored the functional aspect of GABAB receptor activation in sympathetic remodeling. RESULTS Gamma aminobutyric acid B receptors were expressed on macrophage surface both in vitro and in vivo. GABAB receptor agonist baclofen, GABA promoted macrophage switch to M2. While GABAB receptor antagonist CGP52432 blocked a baclofen induced switch to M2 polarization. GABA and baclofen increased M2 macrophage percentage and CGP52432 blocked this process in vivo. Also, IL-10 and TGF-β1 released by M2 were increased in both AMI and baclofen/AMI group; Serum NE levels were decreased by baclofen. All the above effects were reversed by CGP52432 treatment. Baclofen decreased TH and GAP-43 staining while CGP52432 enhanced their expression post AMI indicating GABAB receptor activation inhibited sympathetic nerve sprouting and activity by reducing NE release. CONCLUSIONS Gamma aminobutyric acid B receptor activation promoted M2 polarization and protested AMI heart by regulating sympathetic nerve remodeling.
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Affiliation(s)
- Qian Liu
- Department of Cardiology, Shandong Qianfoshan Hospital, Cheeloo College of Medicine, Shandong University, Shandong, China; Department of Cardiology, Zibo Central Hospital, Zibo City, Shandong Province, China
| | - Yan Li
- Department of Cardiology, Shandong Qianfoshan Hospital, Cheeloo College of Medicine, Shandong University, Shandong, China; Translational Medical Research Center, the First Hospital Affiliated to Shandong First Medical University & Shandong Provincial Qianfoshan Hospital, China
| | - Yugen Shi
- Department of Cardiology, Shandong Qianfoshan Hospital, Cheeloo College of Medicine, Shandong University, Shandong, China; Department of Cardiology, the First Hospital Affiliated to Shandong First Medical University & Shandong Provincial Qianfoshan Hospital, China
| | - Jiayu Tan
- Department of Cardiology, Shandong Qianfoshan Hospital, Cheeloo College of Medicine, Shandong University, Shandong, China; Department of Cardiology, the First Hospital Affiliated to Shandong First Medical University & Shandong Provincial Qianfoshan Hospital, China
| | - Wenju Yan
- Department of Cardiology, Shandong Qianfoshan Hospital, Cheeloo College of Medicine, Shandong University, Shandong, China
| | - Junyi Zhang
- Department of Cardiology, Shandong Qianfoshan Hospital, Cheeloo College of Medicine, Shandong University, Shandong, China
| | - Peng Gao
- Department of Cardiology, Shandong Qianfoshan Hospital, Cheeloo College of Medicine, Shandong University, Shandong, China; Translational Medical Research Center, the First Hospital Affiliated to Shandong First Medical University & Shandong Provincial Qianfoshan Hospital, China
| | - Suhua Yan
- Department of Cardiology, Shandong Qianfoshan Hospital, Cheeloo College of Medicine, Shandong University, Shandong, China; Translational Medical Research Center, the First Hospital Affiliated to Shandong First Medical University & Shandong Provincial Qianfoshan Hospital, China; Department of Cardiology, the First Hospital Affiliated to Shandong First Medical University & Shandong Provincial Qianfoshan Hospital, China.
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Huszár J, Petró JL, Hadady Z, Bobok AÁ, Sághy K, Halász AS, Hornyánszky G, Román V, Greiner I, Éles J. 6-Aryl-quinazolines as novel GABA B receptor positive allosteric modulators. Bioorg Med Chem Lett 2022; 67:128714. [PMID: 35367591 DOI: 10.1016/j.bmcl.2022.128714] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 03/11/2022] [Accepted: 03/28/2022] [Indexed: 11/02/2022]
Abstract
The systemic use of GABAB orthosteric agonist baclofen might be limited due to its detrimental properties: sedation and motor impairment. In contrast, GABAB positive allosteric modulators produce less adverse effects. Using BHF-177 as a starting point, we found a new active scaffold: the 6-aryl-quinazoline scaffold. Further elaborating the scaffold, we identified several in vitro and in vivo active compounds.
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Affiliation(s)
- József Huszár
- Chemical Works of Gedeon Richter Plc, 30-32 Gyömrői Street, Budapest H-1103, Hungary.
| | - József Levente Petró
- Chemical Works of Gedeon Richter Plc, 30-32 Gyömrői Street, Budapest H-1103, Hungary
| | - Zsuzsa Hadady
- Chemical Works of Gedeon Richter Plc, 30-32 Gyömrői Street, Budapest H-1103, Hungary
| | - Amrita Ágnes Bobok
- Chemical Works of Gedeon Richter Plc, 30-32 Gyömrői Street, Budapest H-1103, Hungary
| | - Katalin Sághy
- Chemical Works of Gedeon Richter Plc, 30-32 Gyömrői Street, Budapest H-1103, Hungary
| | - Attila Sándor Halász
- Chemical Works of Gedeon Richter Plc, 30-32 Gyömrői Street, Budapest H-1103, Hungary
| | - Gábor Hornyánszky
- Department of Organic Chemistry and Technology, Budapest University of Technology and Economics, 8 Budafoki Street, Budapest H-1111, Hungary
| | - Viktor Román
- Chemical Works of Gedeon Richter Plc, 30-32 Gyömrői Street, Budapest H-1103, Hungary
| | - István Greiner
- Chemical Works of Gedeon Richter Plc, 30-32 Gyömrői Street, Budapest H-1103, Hungary
| | - János Éles
- Chemical Works of Gedeon Richter Plc, 30-32 Gyömrői Street, Budapest H-1103, Hungary
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Zaupa M, Naini SMA, Younes MA, Bullier E, Duboué ER, Le Corronc H, Soula H, Wolf S, Candelier R, Legendre P, Halpern ME, Mangin JM, Hong E. Trans-inhibition of axon terminals underlies competition in the habenulo-interpeduncular pathway. Curr Biol 2021; 31:4762-4772.e5. [PMID: 34529937 DOI: 10.1016/j.cub.2021.08.051] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 07/12/2021] [Accepted: 08/18/2021] [Indexed: 11/19/2022]
Abstract
Survival of animals is dependent on the correct selection of an appropriate behavioral response to competing external stimuli. Theoretical models have been proposed and underlying mechanisms are emerging to explain how one circuit is selected among competing neural circuits. The evolutionarily conserved forebrain to midbrain habenulo-interpeduncular nucleus (Hb-IPN) pathway consists of cholinergic and non-cholinergic neurons, which mediate different aversive behaviors. Simultaneous calcium imaging of neuronal cell bodies and of the population dynamics of their axon terminals reveals that signals in the cell bodies are not reflective of terminal activity. We find that axon terminals of cholinergic and non-cholinergic habenular neurons exhibit stereotypic patterns of spontaneous activity that are negatively correlated and localize to discrete subregions of the target IPN. Patch-clamp recordings show that calcium bursts in cholinergic terminals at the ventral IPN trigger excitatory currents in IPN neurons, which precede inhibition of non-cholinergic terminals at the adjacent dorsal IPN. Inhibition is mediated through presynaptic GABAB receptors activated in non-cholinergic habenular neurons upon GABA release from the target IPN. Together, the results reveal a hardwired mode of competition at the terminals of two excitatory neuronal populations, providing a physiological framework to explore the relationship between different aversive responses.
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Affiliation(s)
- Margherita Zaupa
- INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), Sorbonne Université, 75005 Paris, France
| | - Seyedeh Maryam Alavi Naini
- INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), Sorbonne Université, 75005 Paris, France
| | - Maroun Abi Younes
- INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), Sorbonne Université, 75005 Paris, France
| | - Erika Bullier
- INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), Sorbonne Université, 75005 Paris, France
| | - Erik R Duboué
- Jupiter Life Science Initiative, Wilkes Honors College and Charles E. Schmidt College of Science, Florida Atlantic University, Jupiter, FL 33458, USA
| | - Hervé Le Corronc
- INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), Sorbonne Université, 75005 Paris, France
| | - Hédi Soula
- INSERM, Sorbonne Université, Nutriomics, La Pitié Salpétrière, 75013 Paris, France
| | - Sebastien Wolf
- Laboratoire Jean Perrin, CNRS, Sorbonne Université, 75005 Paris, France
| | - Raphaël Candelier
- Laboratoire Jean Perrin, CNRS, Sorbonne Université, 75005 Paris, France
| | - Pascal Legendre
- INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), Sorbonne Université, 75005 Paris, France
| | - Marnie E Halpern
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| | - Jean-Marie Mangin
- INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), Sorbonne Université, 75005 Paris, France
| | - Elim Hong
- INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), Sorbonne Université, 75005 Paris, France.
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Varani AP, Pedrón VT, Aon AJ, Canero EM, Balerio GN. GABA B receptors blockage modulates somatic and aversive manifestations induced by nicotine withdrawal. Biomed Pharmacother 2021; 140:111786. [PMID: 34144406 DOI: 10.1016/j.biopha.2021.111786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 05/21/2021] [Accepted: 05/25/2021] [Indexed: 10/21/2022] Open
Abstract
There is substantial evidence that GABAB agonist, baclofen, prevents somatic and motivational responses induced by nicotine withdrawal and may target drug cue vulnerabilities in humans. In this context, we explored different aspects associated with the possible mechanisms whereby the GABAB receptors might influence nicotine withdrawal. Male mice received nicotine (2.5 mg/kg, s.c.) 4 times daily, for 7 consecutive days. Nicotine-treated mice received the nicotinic acetylcholine receptor antagonist, mecamylamine (MEC, 2 or 3.5 mg/kg, s.c.), to precipitate the withdrawal state. A second group of dependent mice received 2-hydroxysaclofen (GABAB receptor antagonist, 1 mg/kg, s.c.) before MEC-precipitated abstinence. Somatic signs of nicotine withdrawal were measured for 30 min. Anxiogenic-like response associated to nicotine withdrawal was assessed by the elevated plus maze test. The dysphoric/aversive effect induced by nicotine withdrawal was evaluated using conditioned place aversion paradigm. Dopamine, serotonin and its metabolites concentrations were determined by HPLC in the striatum, cortex and hippocampus. Finally, α4β2 nicotinic acetylcholine receptor density was determined in several brain regions using autoradiography assays. The results showed that MEC-precipitated nicotine withdrawal induced somatic manifestations, anxiogenic-like response and dysphoric/aversive effect, and 2-hydroxysaclofen potentiated these behavioral responses. Additionally, 2-hydroxysaclofen was able to change striatal dopamine levels and α4β2 nicotinic acetylcholine receptor density, both altered by MEC-precipitated nicotine withdrawal. These findings provide important contributions to elucidate neurobiological mechanisms implicated in nicotine withdrawal. We suggest that GABAB receptor activity is necessary to control alterations induced by nicotine withdrawal, which supports the idea of targeting GABAB receptors to treat tobacco addiction in humans.
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Affiliation(s)
- A P Varani
- CONICET, Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Instituto de Investigaciones Farmacológicas (ININFA-UBA-CONICET), Junín 956, 5° Piso, Buenos Aires C1113AAD, Argentina
| | - V T Pedrón
- CONICET, Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Instituto de Investigaciones Farmacológicas (ININFA-UBA-CONICET), Junín 956, 5° Piso, Buenos Aires C1113AAD, Argentina
| | - A J Aon
- CONICET, Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Instituto de Investigaciones Farmacológicas (ININFA-UBA-CONICET), Junín 956, 5° Piso, Buenos Aires C1113AAD, Argentina
| | - E M Canero
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica (FFYB), Cátedra de Farmacología, Junín 956, 5° Piso, Buenos Aires C1113AAD, Argentina; CONICET, Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Instituto de Investigaciones Farmacológicas (ININFA-UBA-CONICET), Junín 956, 5° Piso, Buenos Aires C1113AAD, Argentina
| | - G N Balerio
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica (FFYB), Cátedra de Farmacología, Junín 956, 5° Piso, Buenos Aires C1113AAD, Argentina; CONICET, Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Instituto de Investigaciones Farmacológicas (ININFA-UBA-CONICET), Junín 956, 5° Piso, Buenos Aires C1113AAD, Argentina.
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Ellaithy A, Gonzalez-Maeso J, Logothetis DA, Levitz J. Structural and Biophysical Mechanisms of Class C G Protein-Coupled Receptor Function. Trends Biochem Sci 2020; 45:1049-1064. [PMID: 32861513 PMCID: PMC7642020 DOI: 10.1016/j.tibs.2020.07.008] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 07/22/2020] [Accepted: 07/30/2020] [Indexed: 02/07/2023]
Abstract
Groundbreaking structural and spectroscopic studies of class A G protein-coupled receptors (GPCRs), such as rhodopsin and the β2 adrenergic receptor, have provided a picture of how structural rearrangements between transmembrane helices control ligand binding, receptor activation, and effector coupling. However, the activation mechanism of other GPCR classes remains more elusive, in large part due to complexity in their domain assembly and quaternary structure. In this review, we focus on the class C GPCRs, which include metabotropic glutamate receptors (mGluRs) and gamma-aminobutyric acid B (GABAB) receptors (GABABRs) most prominently. We discuss the unique biophysical questions raised by the presence of large extracellular ligand-binding domains (LBDs) and constitutive homo/heterodimerization. Furthermore, we discuss how recent studies have begun to unravel how these fundamental class C GPCR features impact the processes of ligand binding, receptor activation, signal transduction, regulation by accessory proteins, and crosstalk with other GPCRs.
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Affiliation(s)
- Amr Ellaithy
- Department of Neurology, University of Iowa, Iowa City, IA 52242, USA; Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA; Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Javier Gonzalez-Maeso
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA 23298, USA
| | - Diomedes A Logothetis
- Department of Pharmaceutical Sciences, School of Pharmacy, Bouvé College of Health Sciences, Northeastern University, Boston, MA 02115, USA; Department of Chemistry and Chemical Biology, College of Science and Center for Drug Discovery, Northeastern University, Boston, MA 02115, USA
| | - Joshua Levitz
- Department of Biochemistry, Weill Cornell Medicine, New York, NY 10065, USA.
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Li F, Sami A, Noristani HN, Slattery K, Qiu J, Groves T, Wang S, Veerasammy K, Chen YX, Morales J, Haynes P, Sehgal A, He Y, Li S, Song Y. Glial Metabolic Rewiring Promotes Axon Regeneration and Functional Recovery in the Central Nervous System. Cell Metab 2020; 32:767-785.e7. [PMID: 32941799 DOI: 10.1016/j.cmet.2020.08.015] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 07/07/2020] [Accepted: 08/26/2020] [Indexed: 12/25/2022]
Abstract
Axons in the mature central nervous system (CNS) fail to regenerate after axotomy, partly due to the inhibitory environment constituted by reactive glial cells producing astrocytic scars, chondroitin sulfate proteoglycans, and myelin debris. We investigated this inhibitory milieu, showing that it is reversible and depends on glial metabolic status. We show that glia can be reprogrammed to promote morphological and functional regeneration after CNS injury in Drosophila via increased glycolysis. This enhancement is mediated by the glia derived metabolites: L-lactate and L-2-hydroxyglutarate (L-2HG). Genetically/pharmacologically increasing or reducing their bioactivity promoted or impeded CNS axon regeneration. L-lactate and L-2HG from glia acted on neuronal metabotropic GABAB receptors to boost cAMP signaling. Local application of L-lactate to injured spinal cord promoted corticospinal tract axon regeneration, leading to behavioral recovery in adult mice. Our findings revealed a metabolic switch to circumvent the inhibition of glia while amplifying their beneficial effects for treating CNS injuries.
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Mugnaini C, Brizzi A, Mostallino R, Castelli MP, Corelli F. Structure optimization of positive allosteric modulators of GABA B receptors led to the unexpected discovery of antagonists/potential negative allosteric modulators. Bioorg Med Chem Lett 2020; 30:127443. [PMID: 32730942 DOI: 10.1016/j.bmcl.2020.127443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 07/21/2020] [Accepted: 07/23/2020] [Indexed: 11/25/2022]
Abstract
Positive allosteric modulators (PAMs) of GABAB receptor represent an interesting alternative to receptor agonists such as baclofen, as they act on the receptor in a more physiological way and thus are devoid of the side effects typically exerted by the agonists. Based on our interest in the identification of new GABAB receptor PAMs, we followed a merging approach to design new chemotypes starting from selected active compounds, such as GS39783, rac-BHFF, and BHF177, and we ended up with the synthesis of four different classes of compounds. The new compounds were tested alone or in the presence of 10 µM GABA using [35S]GTPγS binding assay to assess their functionality at the receptor. Unexpectedly, a number of them significantly inhibited GABA-stimulated GTPγS binding thus revealing a functional switch with respect to the prototype molecules. Further studies on selected compounds will clarify if they act as negative modulators of the receptor or, instead, as antagonists at the orthosteric binding site.
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Affiliation(s)
- Claudia Mugnaini
- Department of Biotechnology, Chemistry, and Pharmacy, University of Siena, I-53100 Siena, SI, Italy.
| | - Antonella Brizzi
- Department of Biotechnology, Chemistry, and Pharmacy, University of Siena, I-53100 Siena, SI, Italy
| | - Rafaela Mostallino
- Department of Biomedical Sciences, University of Cagliari, 09042 Monserrato, Italy
| | - Maria Paola Castelli
- Department of Biomedical Sciences, University of Cagliari, 09042 Monserrato, Italy; Guy Everett Laboratory, University of Cagliari, 09042 Monserrato, Italy; Center of Excellence "Neurobiology of Addiction", University of Cagliari, 09042 Monserrato, Italy.
| | - Federico Corelli
- Department of Biotechnology, Chemistry, and Pharmacy, University of Siena, I-53100 Siena, SI, Italy
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Migita K, Nishimura A, Eto F, Koga K, Matsumoto T, Terada K, Hara S, Honda K. Muscarinic M 1 receptors stimulated by intracerebroventricular administration of McN-A-343 reduces the nerve injury-induced mechanical hypersensitivity via GABA B receptors rather than GABA A receptors in mice. J Pharmacol Sci 2020; 142:50-9. [PMID: 31818640 DOI: 10.1016/j.jphs.2019.06.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 06/14/2019] [Accepted: 06/21/2019] [Indexed: 01/26/2023] Open
Abstract
Cholinergic neurons play an important role in the higher functions of the brain, such as the memory, cognition, and nociception. However, the exact mechanism behind how the stimulation of all the muscarinic M1 receptors in the entire brain results in the alleviation of partial sciatic nerve ligation (PSNL)-induced mechanical hypersensitivity has not been investigated. Thus, we examined which subtype of GABA receptor was involved in the alleviation of PSNL-induce mechanical hypersensitivity produced by an intracerebroventricular administration of a muscarinic M1 receptor agonist, McN-A-343. Administering a GABAA receptor antagonist, bicuculline, resulted in no changes to the McN-A-343-induced anti-hypersensitivity in PSNL mice whereas a GABAB receptor antagonist, CGP35348, dose-dependently inhibited the anti-hypersensitivity. Furthermore, CGP35348 increased mechanical hypersensitivity in naïve mice, and the hypersensitivity was blocked by NMDA receptor antagonists, MK-801 and D-AP5. Additionally, muscarinic M1 receptors colocalized with GABAB1 receptors and an NMDA receptor subunit, GluN2A, in a large region of the brain. Consequently, these results suggest that the activation of muscarinic M1 receptors in the entire brain reduces nerve injury-induced mechanical hypersensitivity via the GABAB receptors, and the activation of the GABAB receptors regulates glutamatergic transmission via NMDA receptors.
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Serikawa T, Kunisawa N, Shimizu S, Kato M, Alves Iha H, Kinboshi M, Nishikawa H, Shirakawa Y, Voigt B, Nakanishi S, Kuramoto T, Kaneko T, Yamamoto T, Mashimo T, Sasa M, Ohno Y. Increased seizure sensitivity, emotional defects and cognitive impairment in PHD finger protein 24 (Phf24)-null rats. Behav Brain Res 2019; 369:111922. [PMID: 31039378 DOI: 10.1016/j.bbr.2019.111922] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 04/18/2019] [Accepted: 04/19/2019] [Indexed: 12/18/2022]
Abstract
Phf24 is known as Gαi-interacting protein (GINIP) and is associated with the GABAB receptor. To study the function of Phf24 protein in the central nervous system (CNS), we have newly developed Phf24-null rats and investigated their behavioral phenotypes, especially changes in seizure sensitivity, emotional responses and cognitive functions. Phf24-null rats did not exhibit any spontaneous seizures. However, they showed a higher sensitivity to pentylenetetrazol (PTZ)- or pilocarpine-induced convulsive seizures. Phf24-null rats also showed an elevated susceptibility to kindling development with repeated PTZ treatments, suggesting that Phf24 acts as an inhibitory modulator in epileptogenesis. Although young Phf24-null rats showed normal gross behaviors, elevated spontaneous locomotor activity, especially in terms of the circadian dark period, emotional hyper-reactivity, reduced anxiety behaviors in the elevated plus-maze (EPM) test, and cognitive deficits in the Morris water maze test were explicitly observed at older age (20-week-old). The present results suggest that Phf24 is essential for proper functioning of the CNS, especially in preventing epileptogenesis and controlling emotional and cognitive functions.
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Affiliation(s)
- Tadao Serikawa
- Institute of Laboratory Animals, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan; Department of Pharmacology, Osaka University of Pharmacological Sciences, Osaka 569-1094, Japan
| | - Naofumi Kunisawa
- Department of Pharmacology, Osaka University of Pharmacological Sciences, Osaka 569-1094, Japan
| | - Saki Shimizu
- Department of Pharmacology, Osaka University of Pharmacological Sciences, Osaka 569-1094, Japan
| | - Masaki Kato
- Department of Pharmacology, Osaka University of Pharmacological Sciences, Osaka 569-1094, Japan
| | - Higor Alves Iha
- Department of Pharmacology, Osaka University of Pharmacological Sciences, Osaka 569-1094, Japan
| | - Masato Kinboshi
- Department of Pharmacology, Osaka University of Pharmacological Sciences, Osaka 569-1094, Japan
| | | | | | - Birger Voigt
- Institute of Laboratory Animals, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan
| | - Satoshi Nakanishi
- Institute of Laboratory Animals, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan
| | - Takashi Kuramoto
- Institute of Laboratory Animals, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan; Department of Animal Science, Tokyo University of Agriculture, Kanagawa 243-0034, Japan
| | - Takehito Kaneko
- Institute of Laboratory Animals, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan; Department of Chemistry and Biological Sciences, Fuculty of Science and Engineering, Iwate University, Iwate 020-8551, Japan
| | - Takashi Yamamoto
- Department of Molecular Genetics, Graduate School of Mathematical and Life Sciences, Hiroshima University, Hiroshima 739-8526, Japan
| | - Tomoji Mashimo
- Institute of Laboratory Animals, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan; Genome Editing Research and Development Center, Graduate School of Medicine, Osaka University, Osaka 565-0871, Japan
| | | | - Yukihiro Ohno
- Department of Pharmacology, Osaka University of Pharmacological Sciences, Osaka 569-1094, Japan.
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Maccioni P, Colombo G, Lorrai I, Fara F, Carai MA, Gessa GL, Brizzi A, Mugnaini C, Corelli F. Anti-addictive properties of COR659 - Additional pharmacological evidence and comparison with a series of novel analogues. Alcohol 2019; 75:55-66. [PMID: 30445248 DOI: 10.1016/j.alcohol.2018.05.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Revised: 05/12/2018] [Accepted: 05/14/2018] [Indexed: 01/01/2023]
Abstract
A recent study found that COR659 (methyl 2-[(4-chlorophenyl)carboxamido]-4-ethyl-5-methylthiophene-3-carboxylate) reduced operant alcohol and chocolate self-administration in rats; COR659 also suppressed cue-induced reinstatement of chocolate seeking in rats. COR659 apparently exerts its effects via a composite mechanism, including positive allosteric modulation of the GABAB receptor and an action at the cannabinoid CB1 receptor. The present study investigated whether the reducing effect of COR659 on alcohol and chocolate self-administration was maintained after repeated treatment and if COR659 affected cue-induced reinstatement of alcohol seeking; additionally, it evaluated the ability of 9 structural analogues of COR659 - designed modifying the substituents on the phenylcarboxamido moiety and replacing the thiophene with the pyridine ring - to affect alcohol and chocolate self-administration. Alcohol self-administration experiments employed Sardinian alcohol-preferring (sP) rats trained to lever-respond for alcohol (15% v/v). Chocolate self-administration experiments employed Wistar rats trained to lever-respond for a chocolate solution (5% w/v Nesquik®). In the reinstatement experiment, previously extinguished lever-responding for alcohol in sP rats was reinstated by the non-contingent presentation of an alcohol-associated complex of cues. All drugs were tested at the doses of 0, 2.5, 5, and 10 mg/kg (i.p.). 10-Day treatment with COR659 produced a dose-related reduction of both alcohol and chocolate self-administration, with limited loss of efficacy on continuing treatment. Acute COR659 suppressed reinstatement of alcohol seeking. Among the 9 tested analogues, only COR657 (methyl 2-(benzoylamino)-4-ethyl-5-methylthiophene-3-carboxylate) decreased alcohol self-administration similarly to COR659; all other compounds produced modest, or even no, effect on alcohol self-administration. COR659 excluded, no compound altered chocolate self-administration. These results confirm and extend the ability of COR659 to reduce several behaviors motivated by alcohol and palatable food in rats. Comparison of COR659 to its analogues provided disparate results that do not currently allow any conclusive structure-activity relationship to be hypothesized, as their diverse pharmacological profile apparently does not depend on physicochemical properties.
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Maccioni P, Fara F, Lorrai I, Acciaro C, Mugnaini C, Corelli F, Colombo G. Suppressing effect of CMPPE, a new positive allosteric modulator of the GABA B receptor, on alcohol self-administration and reinstatement of alcohol seeking in rats. Alcohol 2019; 75:79-87. [PMID: 30468987 DOI: 10.1016/j.alcohol.2018.05.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Revised: 05/18/2018] [Accepted: 05/29/2018] [Indexed: 01/04/2023]
Abstract
Positive allosteric modulators (PAMs) of the GABAB receptor constitute a class of pharmacological agents gaining increasing attention in the alcohol research field because of their ability to suppress several alcohol-related behaviors in rodents. CMPPE is a novel GABAB PAM, still limitedly characterized in vivo. It was therefore of interest to test its ability to affect operant, oral self-administration of alcohol and cue-induced reinstatement of alcohol seeking in alcohol-preferring rats. To this end, female Sardinian alcohol-preferring (sP) rats were trained to lever-respond for alcohol (15% v/v) under the fixed ratio (FR) 5 (FR5) schedule of reinforcement. Once lever-responding had stabilized, rats were exposed to test sessions (under the FR5 [Experiment 1] and progressive ratio [PR; Experiment 2] schedules of reinforcement) preceded by treatment with CMPPE (0, 2.5, 5, and 10 mg/kg; intraperitoneally [i.p.]). In Experiment 3, once lever-responding had stabilized, rats underwent an extinction responding phase and then a single reinstatement session during which lever-responding was resumed by the non-contingent presentation of a complex of alcohol-associated cues; CMPPE (0, 2.5, 5, and 10 mg/kg; i.p.) was administered before the reinstatement session. Selectivity of CMPPE action was assessed by evaluating the effect of CMPPE (0, 2.5, 5, and 10 mg/kg; i.p.) on self-administration of a chocolate solution in male Wistar rats (Experiment 4). In Experiments 1 and 2, treatment with 5 and 10 mg/kg CMPPE reduced lever-responding and breakpoint for alcohol. In Experiment 3, treatment with 5 and 10 mg/kg CMPPE suppressed reinstatement of alcohol seeking. In Experiment 4, no dose of CMPPE affected lever-responding for the chocolate solution. These results extend to CMPPE the ability of all previously tested GABAB PAMs to affect alcohol-motivated behaviors in rodents and confirm that these effects are a shared feature of the entire class of GABAB PAMs. This conclusion is of relevance in view of the forthcoming transition of GABAB PAMs to clinical testing.
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Affiliation(s)
- Paola Maccioni
- Neuroscience Institute, Section of Cagliari, National Research Council of Italy, I-09042 Monserrato, CA, Italy
| | - Federica Fara
- Neuroscience Institute, Section of Cagliari, National Research Council of Italy, I-09042 Monserrato, CA, Italy
| | - Irene Lorrai
- Neuroscience Institute, Section of Cagliari, National Research Council of Italy, I-09042 Monserrato, CA, Italy; Department of Biomedical Sciences, University of Cagliari, I-09042 Monserrato, CA, Italy
| | - Carla Acciaro
- Neuroscience Institute, Section of Cagliari, National Research Council of Italy, I-09042 Monserrato, CA, Italy
| | - Claudia Mugnaini
- Department of Biotechnology, Chemistry, and Pharmacy, University of Siena, I-53100 Siena, SI, Italy
| | - Federico Corelli
- Department of Biotechnology, Chemistry, and Pharmacy, University of Siena, I-53100 Siena, SI, Italy
| | - Giancarlo Colombo
- Neuroscience Institute, Section of Cagliari, National Research Council of Italy, I-09042 Monserrato, CA, Italy.
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Xiong Z, Zhang K, Ren Q, Chang L, Chen J, Hashimoto K. Increased expression of inwardly rectifying Kir4.1 channel in the parietal cortex from patients with major depressive disorder. J Affect Disord 2019; 245:265-269. [PMID: 30419525 DOI: 10.1016/j.jad.2018.11.016] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Revised: 09/22/2018] [Accepted: 11/03/2018] [Indexed: 12/25/2022]
Abstract
BACKGROUND The inwardly rectifying K+ channel subtype Kir4.1 has been well studied in the astrocyte within brain; however, the precise role of this protein in psychiatric disorders is unknown. Kir4.1 is also known to interact with GABAB receptors which may be implicated in psychiatric disorders. Here we studied whether expression of Kir4.1 and GABAB receptors was altered in the postmortem brain samples (parietal cortex and cerebellum) from patients with major psychiatric disorders. METHODS Protein expression of Kir4.1 and GABAB receptors in the parietal cortex and cerebellum from control, major depressive disorder (MDD), schizophrenia (SZ), and bipolar disorder (BD) groups was measured. RESULTS Levels of Kir4.1 in the parietal cortex from MDD group, but not SZ and BD groups, were significantly higher than the control group. Furthermore, levels of GABAB receptor subunit 1 in the parietal cortex from MDD group and SZ group, but not BD group, were also significantly higher than the control group. Interestingly, there was a positive correlation between Kir4.1 protein and GABAB receptor subunit 1 in the parietal cortex from control group, but not MDD group. LIMITATIONS The small number in each group may limit our interpretation. Only two brain regions were analyzed. CONCLUSIONS Abnormalities in the interaction of Kir4.1 and GABAB receptor in the parietal cortex might play a role in the pathophysiology of MDD.
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Affiliation(s)
- Zhongwei Xiong
- Division of Clinical Neuroscience, Chiba University Center for Forensic Mental Health, Chiba 260-8670, Japan; Department of Neurosurgery, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan 430071, PR China
| | - Kai Zhang
- Division of Clinical Neuroscience, Chiba University Center for Forensic Mental Health, Chiba 260-8670, Japan
| | - Qian Ren
- Division of Clinical Neuroscience, Chiba University Center for Forensic Mental Health, Chiba 260-8670, Japan
| | - Lijia Chang
- Division of Clinical Neuroscience, Chiba University Center for Forensic Mental Health, Chiba 260-8670, Japan
| | - Jincao Chen
- Department of Neurosurgery, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan 430071, PR China
| | - Kenji Hashimoto
- Division of Clinical Neuroscience, Chiba University Center for Forensic Mental Health, Chiba 260-8670, Japan.
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Svejgaard B, Andreasen M, Nedergaard S. Role of GABA B receptors in proepileptic and antiepileptic effects of an applied electric field in rat hippocampus in vitro. Brain Res 2018; 1710:157-162. [PMID: 30599137 DOI: 10.1016/j.brainres.2018.12.043] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Revised: 12/03/2018] [Accepted: 12/28/2018] [Indexed: 01/24/2023]
Abstract
The mechanisms underlying antiepileptic effects of deep brain stimulation (DBS) are complex and poorly understood. Studies on the effects of applied electric fields on epileptic nervous tissue could enable future advances in DBS treatments. Applied electric fields are known to inhibit or enhance epileptic activity in vitro through direct effects on local neurons, but it is unclear whether trans-synaptic effects participate in such actions. The present study investigates, in an epileptic brain slice model, the influence of GABAB receptor activation on excitatory and suppressive effects of a short-duration (10 ms) electric field in rat hippocampus. The results show that perfusion of the GABAB receptor antagonist, CGP 55845 (2 μM), could abolish applied-field induced suppression of orthodromic-stimulus evoked epileptiform afterdischarge activity in the CA1 region. GABAB receptor blockade was associated with an enhanced excitatory (proepileptic) effect of the applied field. However, the suppressive effect, observed in isolation using weak field stimuli, was left unchanged. The G-protein-activated inwardly rectifying K+ channel (GIRK) antagonist, tertiapin (30-50 nM), mimicked the effects of CGP 55845. The results suggest that the applied field activate (elements of) local interneurons to release GABA onto GABAB receptors. The resulting activation of postsynaptic GIRK channels inhibits neuronal activity thereby dampening the direct stimulatory effect of the applied field. The study indicates that local-stimulus induced GABAB receptor activation can serve a protective role under antiepileptic paradigms by preventing electrical stimulation from causing hyperexcitation.
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Affiliation(s)
| | - Mogens Andreasen
- Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Steen Nedergaard
- Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark.
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16
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Söderhielm PC, Klein AB, Bomholtz SH, Jensen AA. Profiling of GABA A and GABA B receptor expression in the myometrium of the human uterus. Life Sci 2018; 214:145-152. [PMID: 30343129 DOI: 10.1016/j.lfs.2018.10.033] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 10/09/2018] [Accepted: 10/18/2018] [Indexed: 10/28/2022]
Abstract
AIMS γ-aminobutyric acid (GABA) mediates its physiological effects through the GABAA and GABAB receptors. In this study the putative expression of GABAAR and GABABR subunits in human myometrium tissue was investigated. MAIN METHODS The expression levels of the 19 GABAAR subunits (α1-α6, β1-β3, γ1-γ3, δ, ε, π, θ, ρ1-ρ3) and the three GABABR subunits (GABAB1a, GABAB1b, GABAB2) were characterized by RT-qPCR analysis on two commercial samples and six samples derived from surgically removed myometrial tissues from different women. We probed for functional GABAAR expression in primary human myometrial smooth muscle cells (HMSMCs) by whole-cell patch-clamp electrophysiology. KEY FINDINGS The absolute mRNA levels of the 22 GABAAR and GABABR genes varied considerably across the eight samples, but a pronounced overlap existed between the specific subunits detected in the samples, with α2, β2, β3, ε, π, θ, GABAB1a and GABAB1b mRNAs being detected in most samples. The expression profile of GABAAR and GABABR subunit mRNAs in HMSMCs correlated with that observed in the eight tissue samples, albeit the subunit transcripts were detected at lower relative levels. Neither muscimol nor GABA evoked significant currents in these cells in the patch-clamp recordings. SIGNIFICANCE While the expression of the GABAB1 subunits on their own is unlikely to give rise to functional GABABR expression, the GABAAR subunits identified at mRNA level would be able to form functional receptors in the human myometrial tissue. Although GABAAR-mediated currents could not be recorded from HMSMCs in this study, this suggests a role for GABAergic transmission in the human myometrium.
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Affiliation(s)
- Pella Cecilia Söderhielm
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen Ø, Denmark
| | - Anders Bue Klein
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen Ø, Denmark
| | - Sofia Hammami Bomholtz
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen, N, Denmark
| | - Anders A Jensen
- 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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Watanabe Y, Aono Y, Komiya M, Waddington JL, Saigusa T. Stimulation of accumbal GABA B receptors inhibits delta1- and delta2-opioid receptor-mediated dopamine efflux in the nucleus accumbens of freely moving rats. Eur J Pharmacol 2018; 837:88-95. [PMID: 30086266 DOI: 10.1016/j.ejphar.2018.08.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 08/01/2018] [Accepted: 08/03/2018] [Indexed: 01/29/2023]
Abstract
The nucleus accumbens contains delta-opioid receptors that may decrease inhibitory neurotransmission. As GABAB receptors inhibit dopamine release, decrease in activation of GABAB receptors may be a mediator of delta-opioid receptor-induced accumbal dopamine efflux. If so, accumbal dopamine efflux induced by delta-opioid receptor activation should be suppressed by stimulating GABAB receptors. As delta-opioid receptors are further subdivided into delta1- and delta2-opioid receptors, we analysed the effects of the GABAB receptor agonist baclofen on delta1- and delta2-opioid receptor-mediated accumbal dopamine efflux in freely moving rats using in vivo microdialysis. Drugs were applied intracerebrally through the dialysis probe. Doses of compounds show total amount administered (mol) during 25-50 min infusions. Baclofen (2.5 and 5.0 nmol), which did not alter basal dopamine levels, inhibited the delta1-opioid receptor agonist DPDPE (5.0 nmol)-induced dopamine efflux. Baclofen (2.5 and 5.0 nmol) also inhibited the delta2-opioid receptor agonist deltorphin II (25.0 nmol)-induced dopamine efflux. A low dose of the GABAB receptor antagonist 2-hydroxysaclofen (100.0 pmol), which failed to alter basal accumbal dopamine levels, counteracted the inhibitory effects of baclofen (5.0 nmol) on DPDPE (5.0 nmol)- and deltorphin II (25.0 nmol)-induced dopamine efflux. The present results show that reduction in accumbal GABAB receptor-mediated inhibition of accumbal dopaminergic activity facilitates activation of delta1- and delta2-opioid receptor-induced increases in accumbal dopamine efflux. This study suggests that activation of delta1- and delta2-opioid receptors on the cell bodies and/or terminals of accumbal GABAergic interneurons inhibits GABA release and, accordingly, decreases GABAB receptor-mediated inhibition of dopaminergic terminals, resulting in enhanced accumbal dopamine efflux.
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Affiliation(s)
- Yuriko Watanabe
- Department of Oral Surgery, Nihon University School of Dentistry at Matsudo, 2-870-1 Sakaecho-Nishi, Matsudo, Chiba 271-8587, Japan; Nihon University Graduate School of Dentistry at Matsudo, Oral Surgery, 2-870-1 Sakaecho-Nishi, Matsudo, Chiba 271-8587, Japan
| | - Yuri Aono
- Department of Pharmacology, Nihon University School of Dentistry at Matsudo, 2-870-1 Sakaecho-Nishi, Matsudo, Chiba 271-8587, Japan
| | - Masamichi Komiya
- Department of Oral Surgery, Nihon University School of Dentistry at Matsudo, 2-870-1 Sakaecho-Nishi, Matsudo, Chiba 271-8587, Japan
| | - John L Waddington
- Molecular and Cellular Therapeutics, Royal College of Surgeons in Ireland, St. Stephen's Green, Dublin 2, Ireland
| | - Tadashi Saigusa
- Department of Pharmacology, Nihon University School of Dentistry at Matsudo, 2-870-1 Sakaecho-Nishi, Matsudo, Chiba 271-8587, Japan.
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Stincic TL, Rønnekleiv OK, Kelly MJ. Diverse actions of estradiol on anorexigenic and orexigenic hypothalamic arcuate neurons. Horm Behav 2018; 104:146-155. [PMID: 29626486 PMCID: PMC6196116 DOI: 10.1016/j.yhbeh.2018.04.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Revised: 03/29/2018] [Accepted: 04/02/2018] [Indexed: 12/13/2022]
Abstract
Contribution to Special Issue on Fast effects of steroids. There is now compelling evidence for membrane-associated estrogen receptors in hypothalamic neurons that are critical for the hypothalamic control of homeostatic functions. It has been known for some time that estradiol (E2) can rapidly alter hypothalamic neuronal activity within seconds, indicating that some cellular effects can occur via membrane initiated events. However, our understanding of how E2 signals via membrane-associated receptors and how these signals impact physiological functions is only just emerging. Thus, E2 can affect second messenger systems including calcium mobilization and a plethora of kinases to alter cell excitability and even gene transcription in hypothalamic neurons. One population of hypothalamic neurons, the anorexigenic proopiomelanocortin (POMC) neurons, has long been considered to be a target of E2's actions based on gene (Pomc) expression studies. However, we now know that E2 can rapidly alter POMC neuronal activity within seconds and activate several intracellular signaling cascades that ultimately affect gene expression, actions which are critical for maintaining sensitivity to insulin in metabolically stressed states. E2 also affects the orexigenic Neuropeptide Y/Agouti-related Peptide (NPY/AgRP) neurons in similarly rapid but antagonistic manner. Therefore, this review will summarize our current state of knowledge of how E2 signals via rapid membrane-initiated and intracellular signaling cascades in POMC and NPY/AgRP neurons to regulate energy homeostasis.
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Affiliation(s)
- Todd L Stincic
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, OR 97239, USA
| | - Oline K Rønnekleiv
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, OR 97239, USA; Department of Anesthesiology and Perioperative Medicine, Oregon Health & Science University, Portland, OR 97239, USA; Division of Neuroscience, Oregon Regional Primate Research Center, Oregon Health & Science University, Beaverton, OR 97006, USA
| | - Martin J Kelly
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, OR 97239, USA; Division of Neuroscience, Oregon Regional Primate Research Center, Oregon Health & Science University, Beaverton, OR 97006, USA.
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Abstract
Metabotropic GABAB receptor is a G protein-coupled receptor (GPCR) that mediates slow and prolonged inhibitory neurotransmission in the brain. It functions as a constitutive heterodimer composed of the GABAB1 and GABAB2 subunits. Each subunit contains three domains; the extracellular Venus flytrap module, seven-helix transmembrane region and cytoplasmic tail. In recent years, the three-dimensional structures of GABAB receptor extracellular and intracellular domains have been elucidated. These structures reveal the molecular basis of ligand recognition, receptor heterodimerization and receptor activation. Here we provide a brief review of the GABAB receptor structures, with an emphasis on describing the different ligand-bound states of the receptor. We will also compare these with the known structures of related GPCRs to shed light on the molecular mechanisms of activation and regulation in the GABAB system, as well as GPCR dimers in general. This article is part of the "Special Issue Dedicated to Norman G. Bowery".
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Affiliation(s)
- Aurel Frangaj
- Department of Pharmacology, Columbia University, New York, NY 10032, USA
| | - Qing R Fan
- Department of Pharmacology, Columbia University, New York, NY 10032, USA; Department of Pathology & Cell Biology, Columbia University, New York, NY 10032, USA.
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20
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Migita K, Matsuzaki Y, Koga K, Matsumoto T, Mishima K, Hara S, Honda K. Involvement of GABA B receptor in the antihypersensitive effect in anterior cingulate cortex of partial sciatic nerve ligation model. J Pharmacol Sci 2018; 137:233-236. [PMID: 30078433 DOI: 10.1016/j.jphs.2018.05.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 05/29/2018] [Accepted: 05/31/2018] [Indexed: 01/23/2023] Open
Abstract
The role of the GABAB receptor in the anterior cingulate cortex (ACC) of neuropathic pain is unclear. Injection of a GABAB receptor antagonist CGP35348 into the ACC induced mechanical hypersensitivity in normal rats. Activation of the GABAB receptor injected by a GABAB receptor agonist baclofen into the ACC attenuated mechanical hypersensitivity in partial sciatic nerve ligation (PSNL) rats. Co-microinjection of CGP35348 with a muscarinic M1 receptor agonist McN-A-343 into the ACC significantly inhibited McN-A-343-induced antihypersensitivity in PSNL rats. These results suggest that the GABAB receptor in the ACC contributes to mechanical hypersensitivity and is involved in muscarinic M1 receptor-mediated antihypersensitivity.
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Affiliation(s)
- Keisuke Migita
- Department of Drug Informatics, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, 814-0180, Japan.
| | - Yu Matsuzaki
- Department of Physiology and Pharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, 814-0180, Japan
| | - Kohei Koga
- Department of Neurophysiology, Hyogo College of Medicine, Nishinomiya, Hyogo, 663-8501, Japan
| | - Taichi Matsumoto
- Department of Drug Informatics, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, 814-0180, Japan
| | - Kenichi Mishima
- Department of Physiology and Pharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, 814-0180, Japan
| | - Shuji Hara
- Department of Drug Informatics, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, 814-0180, Japan
| | - Kenji Honda
- Department of Physiology and Pharmacology, Faculty of Pharmaceutical Sciences, Fukuoka University, Fukuoka, 814-0180, Japan.
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Jacobson LH, Vlachou S, Slattery DA, Li X, Cryan JF. The Gamma-Aminobutyric Acid B Receptor in Depression and Reward. Biol Psychiatry 2018; 83:963-976. [PMID: 29759132 DOI: 10.1016/j.biopsych.2018.02.006] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2017] [Revised: 01/14/2018] [Accepted: 02/06/2018] [Indexed: 12/31/2022]
Abstract
The metabotropic gamma-aminobutyric acid B (GABAB) receptor was the first described obligate G protein-coupled receptor heterodimer and continues to set the stage for discoveries in G protein-coupled receptor signaling complexity. In this review, dedicated to the life and work of Athina Markou, we explore the role of GABAB receptors in depression, reward, and the convergence of these domains in anhedonia, a shared symptom of major depressive disorder and withdrawal from drugs of abuse. GABAB receptor expression and function are enhanced by antidepressants and reduced in animal models of depression. Generally, GABAB receptor antagonists are antidepressant-like and agonists are pro-depressive. Exceptions to this rule likely reflect the differential influence of GABAB1 isoforms in depression-related behavior and neurobiology, including the anhedonic effects of social stress. A wealth of data implicate GABAB receptors in the rewarding effects of drugs of abuse. We focus on nicotine as an example. GABAB receptor activation attenuates, and deactivation enhances, nicotine reward and associated neurobiological changes. In nicotine withdrawal, however, GABAB receptor agonists, antagonists, and positive allosteric modulators enhance anhedonia, perhaps owing to differential effects of GABAB1 isoforms on the dopaminergic system. Nicotine cue-induced reinstatement is more reliably attenuated by GABAB receptor activation. Separation of desirable and undesirable side effects of agonists is achievable with positive allosteric modulators, which are poised to enter clinical studies for drug abuse. GABAB1 isoforms are key to understanding the neurobiology of anhedonia, whereas allosteric modulators may offer a mechanism for targeting specific brain regions and processes associated with reward and depression.
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Affiliation(s)
- Laura H Jacobson
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Victoria, Australia; Department of Pharmacology and Therapeutics, University of Melbourne, Victoria, Australia.
| | - Styliani Vlachou
- School of Nursing and Human Sciences, Faculty of Science and Health, Dublin City University, Glasnevin, Dublin
| | - David A Slattery
- Klinik für Psychiatrie, Psychosomatik und Psychotherapie, Universitätsklinikum Frankfurt, Frankfurt am Main, Germany
| | - Xia Li
- Department of Psychiatry, School of Medicine, University of California San Diego, La Jolla, California
| | - John F Cryan
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland; Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland
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22
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Maccioni P, Lorrai I, Contini A, Leite-Morris K, Colombo G. Microinjection of baclofen and CGP7930 into the ventral tegmental area suppresses alcohol self-administration in alcohol-preferring rats. Neuropharmacology 2017; 136:146-158. [PMID: 29050951 DOI: 10.1016/j.neuropharm.2017.10.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 10/08/2017] [Accepted: 10/11/2017] [Indexed: 01/05/2023]
Abstract
Systemic administration of the orthosteric agonist, baclofen, and several positive allosteric modulators (PAMs) of the GABAB receptor has repeatedly been reported to decrease operant oral alcohol self-administration in rats. The aim of the present study was to evaluate the contribution of the mesolimbic dopamine system to the reducing effect of baclofen and GABAB PAMs on the reinforcing properties of alcohol. To this end, baclofen or the GABAB PAM CGP7930 were microinjected into the ventral tegmental area (VTA) of selectively bred, Sardinian alcohol-preferring (sP) rats trained to self-administer alcohol. Baclofen (0, 0.03, 0.1, and 0.3 μg) or CGP7930 (0, 5, 10, and 20 μg) were microinjected via indwelling unilateral guide cannula aiming at the left hemisphere of the VTA. Treatment with baclofen resulted in a dose-related suppression of the number of lever-responses for alcohol and the amount of self-administered alcohol. No dose of baclofen altered rat motor-performance, evaluated by the inverted screen test immediately before the self-administration session. Treatment with CGP7930 halved the number of lever-responses for alcohol and amount of self-administered alcohol, with no effect on rat motor-performance. Site-specificity was investigated testing the effect of microinjection of baclofen and CGP7930 into the left hemisphere of deep mesencephalic nucleus: compared to vehicle, neither 0.3 μg baclofen nor 20 μg CGP7930 altered lever-responding for alcohol and amount of self-administered alcohol. Collectively, the results of the present study suggest the involvement of GABAB receptors located in the VTA in the mediation of alcohol reinforcing properties in sP rats. This article is part of the "Special Issue Dedicated to Norman G. Bowery".
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Affiliation(s)
- Paola Maccioni
- Neuroscience Institute, Section of Cagliari, National Research Council of Italy, Monserrato, CA I-09042, Italy
| | - Irene Lorrai
- Neuroscience Institute, Section of Cagliari, National Research Council of Italy, Monserrato, CA I-09042, Italy
| | - Andrea Contini
- Department of Biomedical Sciences, University of Sassari, Sassari, SS I-07100, Italy
| | - Kimberly Leite-Morris
- Departments of Psychiatry, Pharmacology and Experimental Therapeutics, Boston University School of Medicine, VA Boston Healthcare System, Research Service, Boston, MA 02130, USA
| | - Giancarlo Colombo
- Neuroscience Institute, Section of Cagliari, National Research Council of Italy, Monserrato, CA I-09042, Italy.
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23
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Kannampalli P, Poli SM, Boléa C, Sengupta JN. Analgesic effect of ADX71441, a positive allosteric modulator (PAM) of GABA B receptor in a rat model of bladder pain. Neuropharmacology 2017; 126:1-11. [PMID: 28823612 DOI: 10.1016/j.neuropharm.2017.08.023] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 07/26/2017] [Accepted: 08/16/2017] [Indexed: 01/12/2023]
Abstract
Therapeutic use of GABAB receptor agonists for conditions like chronic abdominal pain, overactive bladder (OAB) and gastroesophageal reflux disease (GERD) is severely affected by poor blood-brain barrier permeability and potential side effects. ADX71441 is a novel positive allosteric modulator (PAM) of the GABAB receptor that has shown encouraging results in pre-clinical models of anxiety, pain, OAB and alcohol addiction. The present study investigates the analgesic effect of ADX71441 to noxious stimulation of the urinary bladder and colon in rats. In female Sprague-Dawley rats, systemic (i.p), but not intrathecal (i.t), administration of ADX71441 produced a dose-dependent decrease in viscero-motor response (VMR) to graded urinary bladder distension (UBD) and colorectal distension (CRD). Additionally, intra-cerebroventricular (i.c.v.) administration of ADX71441 significantly decreased the VMRs to noxious UBD. In electrophysiology experiments, the drug did not attenuate the responses of UBD-sensitive pelvic nerve afferent (PNA) fibers to UBD. In contrast, ADX71441 significantly decreased the responses of UBD-responsive lumbosacral (LS) spinal neurons in spinal intact rats. However, ADX71441 did not attenuate these LS neurons in cervical (C1-C2) spinal transected rats. During cystometrogram (CMG) recordings, ADX71441 (i.p.) significantly decreased the VMR to slow infusion without affecting the number of voiding contraction. These results indicate that ADX71441 modulate bladder nociception via its effect at the supra-spinal sites without affecting the normal bladder motility and micturition reflex in naïve adult rats.
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Affiliation(s)
- Pradeep Kannampalli
- Division of Gastroenterology and Hepatology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Sonia-Maria Poli
- Addex Therapeutics, 14 Chemin des Aulx, CH-1228 Plan-les-Ouates, Geneva, Switzerland
| | - Christelle Boléa
- Addex Therapeutics, 14 Chemin des Aulx, CH-1228 Plan-les-Ouates, Geneva, Switzerland
| | - Jyoti N Sengupta
- Division of Gastroenterology and Hepatology, Medical College of Wisconsin, Milwaukee, WI, USA; Department of Pediatric Gastroenterology, Medical College of Wisconsin, Milwaukee, WI, USA.
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24
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Pizzo R, O'Leary OF, Cryan JF. Elucidation of the neural circuits activated by a GABA B receptor positive modulator: Relevance to anxiety. Neuropharmacology 2018; 136:129-45. [PMID: 28734870 DOI: 10.1016/j.neuropharm.2017.07.021] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Revised: 07/17/2017] [Accepted: 07/18/2017] [Indexed: 01/09/2023]
Abstract
Although there is much evidence for a role of GABAB receptors in the pathophysiology of anxiety, the underlying neuronal mechanisms are largely unclear. The GABAB receptor allosteric positive modulator, GS39783, exerts anxiolytic effects without interfering with GABAB-mediated modulation of body temperature, cognitive performance and locomotor activity thus offering advantages over GABAB receptor agonists. However, the precise neural circuits underlying the anxiolytic effects of GS39783 are unknown. The aim of the present study was to identify brain structures and associated neuronal circuits that are modulated by GS39783 under either basal or mild stress conditions. To this end, the expression pattern of c-Fos, a marker of neuronal activation, was examined in mice acutely treated with GS39783 under basal conditions or following a mild anxiogenic challenge induced by exposure to the Open Arm (OA) of an Elevated Plus Maze. OA exposure enhanced c-Fos expression in vehicle-treated animals in several brain regions, including the medial prefrontal cortex, lateral septum, amygdala, hippocampus, paraventricular nucleus of the hypothalamus and the periaqueductal gray (PAG). Under basal conditions, GS39783 increased c-Fos in a restricted panel of areas notably amygdala nuclei, cortical areas and PAG subregions, while it inhibited c-Fos expression in the dorsal raphe nucleus (DRN). Under stress conditions, GS39783 reversed OA-induced c-Fos expression in the granular cell layer of the dentate gyrus, no longer increased c-Fos expression in the amygdala nor reduced c-Fos expression in the DRN. These specific patterns of neural activation by GS39783 might explain the neurobiological correlates implicated in GABAB-mediated anti-anxiety effects. This article is part of the "Special Issue Dedicated to Norman G. Bowery".
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25
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Sadeghi M, McArthur JR, Finol-Urdaneta RK, Adams DJ. Analgesic conopeptides targeting G protein-coupled receptors reduce excitability of sensory neurons. Neuropharmacology 2017; 127:116-123. [PMID: 28533165 DOI: 10.1016/j.neuropharm.2017.05.020] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 05/16/2017] [Accepted: 05/18/2017] [Indexed: 01/28/2023]
Abstract
Conotoxins (conopeptides) are a diverse group of peptides isolated from the venom of marine cone snails. Conus peptides modulate pain by interacting with voltage-gated ion channels and G protein-coupled receptors (GPCRs). Opiate drugs targeting GPCRs have long been used, nonetheless, many undesirable side effects associated with opiates have been observed including addiction. Consequently, alternative avenues to pain management are a largely unmet need. It has been shown that various voltage-gated calcium channels (VGCCs) respond to GPCR modulation. Thus, regulation of VGCCs by GPCRs has become a valuable alternative in the management of pain. In this review, we focus on analgesic conotoxins that exert their effects via GPCR-mediated inhibition of ion channels involved in nociception and pain transmission. Specifically, α-conotoxin Vc1.1 activation of GABAB receptors and inhibition of voltage-gated calcium channels as a novel mechanism for reducing the excitability of dorsal root ganglion neurons is described. Vc1.1 and other α-conotoxins have been shown to be analgesic in different animal models of chronic pain. This review will outline the functional effects of conopeptide modulation of GPCRs and how their signalling is translated to downstream components of the pain pathways. Where available we present the proposed signalling mechanisms that couples metabotropic receptor activation to their downstream effectors to produce analgesia. This article is part of the Special Issue entitled 'Venom-derived Peptides as Pharmacological Tools.'
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Affiliation(s)
- Mahsa Sadeghi
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, New South Wales, 2522, Australia
| | - Jeffrey R McArthur
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, New South Wales, 2522, Australia
| | - Rocio K Finol-Urdaneta
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, New South Wales, 2522, Australia
| | - David J Adams
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, New South Wales, 2522, Australia.
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26
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Abstract
Over the past three decades the research on GABAB receptor biology and pharmacology in pain processing has been a fascinating experience. Norman Bowery's fundamental discovery of the existence of the GABAB receptor has led the way to the definition of GABAB molecular mechanisms; patterns of receptor expression in the peripheral and central nervous system; GABAB modulatory functions within the pain pathways. We are now harnessing this acquired knowledge to develop innovative approaches to the therapeutic management of chronic pain through allosteric modulation of the GABAB. Norman's legacy would be ultimately fulfilled by the development of novel analgesics that activate the GABAB receptor. This article is part of the "Special Issue Dedicated to Norman G. Bowery".
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Affiliation(s)
- Marzia Malcangio
- Wolfson Centre for Age Related Diseases, King's College London, London SE1 1UL, UK.
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27
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Olianas MC, Dedoni S, Onali P. The GABA B positive allosteric modulators CGP7930 and GS39783 stimulate ERK1/2 signalling in cells lacking functional GABA B receptors. Eur J Pharmacol 2016; 794:135-146. [PMID: 27876620 DOI: 10.1016/j.ejphar.2016.11.030] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 10/04/2016] [Accepted: 11/18/2016] [Indexed: 02/03/2023]
Abstract
The present study shows that the GABAB positive allosteric modulators (PAMs) CGP7930 and GS39783 stimulate extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) signalling in cells that do not express functional GABAB receptors. In human SH-SY5Y neuroblastoma cells, CGP7930 and GS39783 induced a time- and concentration-dependent increase in ERK1/2 phosphorylation with potencies similar to those displayed as GABAB PAMs. Conversely, γ-aminobutyric acid and the GABAB receptor agonists (-)baclofen and SKF97541 were completely inactive. CGP7930 and GS39783 enhanced the nuclear localization of phospho-ERK1/2 and CGP7930 promoted the phosphorylation of the transcription factors Elk-1 and CREB. CGP7930-induced ERK1/2 stimulation was insensitive to pertussis toxin, the Gq/11 antagonist YM254890 and the phospholipase C-β inhibitor U-73122, but was completely blocked by the MEK1/2 inhibitor PD98059. Inhibition of insulin-like growth factor-1, platelet--derived growth factor, phosphoinositide 3-kinase and Akt activities potentiated CGP7930-induced ERK1/2 phosphorylation. CGP7930 enhanced the phosphorylation of myristoylated alanine-rich protein kinase C (PKC) substrate and inhibition of PKC attenuated the ERK1/2 stimulation. Over-expression of N17Ras, a dominant negative mutant of c-Ras, or inhibition of c-Raf by GW5074 partially antagonized CGP7930-induced ERK1/2 activation. CGP7930 enhanced the phosphorylation of transforming growth factor-β-activated kinase 1 (TAK-1) and TAK-1 inhibition by 5Z-7-oxozeaenol reduced CGP7930-induced ERK1/2 phosphorylation. CGP7930 activated ERK1/2 in CHO-K1 fibroblasts, which lack endogenous GABAB receptors, but not in HEK-293 cells, indicating that the response displayed cell type specificity. These data demonstrate that CGP7930 and GS39783 can trigger ERK1/2 signalling, a critical modulator of mood and drug addiction, independently of an action on GABAB receptors.
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Affiliation(s)
- Maria C Olianas
- Laboratory of Cellular and Molecular Pharmacology, Section of Neurosciences and Clinical Pharmacology, Department of Biomedical Sciences, University of Cagliari, Cagliari, Italy.
| | - Simona Dedoni
- Laboratory of Cellular and Molecular Pharmacology, Section of Neurosciences and Clinical Pharmacology, Department of Biomedical Sciences, University of Cagliari, Cagliari, Italy
| | - Pierluigi Onali
- Laboratory of Cellular and Molecular Pharmacology, Section of Neurosciences and Clinical Pharmacology, Department of Biomedical Sciences, University of Cagliari, Cagliari, Italy
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28
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Beas BS, Setlow B, Bizon JL. Effects of acute administration of the GABA(B) receptor agonist baclofen on behavioral flexibility in rats. Psychopharmacology (Berl) 2016; 233:2787-97. [PMID: 27256354 PMCID: PMC4919234 DOI: 10.1007/s00213-016-4321-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 05/09/2016] [Indexed: 12/20/2022]
Abstract
RATIONALE The ability to adjust response strategies when faced with changes in the environment is critical for normal adaptive behavior. Such behavioral flexibility is compromised by experimental disruption of cortical GABAergic signaling, as well as in conditions such as schizophrenia and normal aging that are characterized by cortical hyperexcitability. The current studies were designed to determine whether stimulation of GABAergic signaling using the GABA(B) receptor agonist baclofen can facilitate behavioral flexibility. METHODS Male Fischer 344 rats were trained in a set-shifting task in which they learned to discriminate between two response levers to obtain a food reward. Correct levers were signaled in accordance with two distinct response rules (rule 1: correct lever signaled by a cue light; rule 2: correct lever signaled by its left/right position). The order of rule presentation varied, but they were always presented sequentially, with the trials and errors to reach criterion performance on the second (set shift) rule providing the measure of behavioral flexibility. Experiments determined the effects of the GABA(B) receptor agonist baclofen (intraperitoneal, 0, 1.0, 2.5, and 4.0 mg/kg) administered acutely before the shift to the second rule. RESULTS Baclofen enhanced set-shifting performance. Control experiments demonstrated that this enhancement was not simply due to improved discrimination learning, nor was it due to impaired recall of the initial discrimination rule. CONCLUSIONS The results demonstrate that baclofen can facilitate behavioral flexibility, suggesting that GABA(B) receptor agonists may have utility for treating behavioral dysfunction in neuropsychiatric disorders.
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Affiliation(s)
- B. Sofia Beas
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, FL
| | - Barry Setlow
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, FL,Department of Psychiatry, University of Florida College of Medicine, Gainesville, FL
| | - Jennifer L. Bizon
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, FL,Department of Psychiatry, University of Florida College of Medicine, Gainesville, FL
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29
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Crowley T, Cryan JF, Downer EJ, O'Leary OF. Inhibiting neuroinflammation: The role and therapeutic potential of GABA in neuro-immune interactions. Brain Behav Immun 2016; 54:260-277. [PMID: 26851553 DOI: 10.1016/j.bbi.2016.02.001] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Revised: 01/22/2016] [Accepted: 02/02/2016] [Indexed: 12/25/2022] Open
Abstract
The central nervous system, once thought to be a site of immunological privilege, has since been found to harbour immunocompetent cells and to communicate with the peripheral nervous system. In the central nervous system (CNS), glial cells display immunological responses to pathological and physiological stimuli through pro- and anti-inflammatory cytokine and chemokine signalling, antigen presentation and the clearing of cellular debris through phagocytosis. While this neuroinflammatory signalling can act to reduce neuronal damage and comprises a key facet of CNS homeostasis, persistent inflammation or auto-antigen-mediated immunoreactivity can induce a positive feedback cycle of neuroinflammation that ultimately results in necrosis of glia and neurons. Persistent neuroinflammation has been recognised as a major pathological component of virtually all neurodegenerative diseases and has also been a focus of research into the pathology underlying psychiatric disorders. Thus, pharmacological strategies to curb the pathological effects of persistent neuroinflammation are of interest for many disorders of the CNS. Accumulating evidence suggests that GABAergic activities are closely bound to immune processes and signals, and thus the GABAergic neurotransmitter system might represent an important therapeutic target in modulating neuroinflammation. Here, we review evidence that inflammation induces changes in the GABA neurotransmitter system in the CNS and that GABAergic signalling exerts a reciprocal influence over neuroinflammatory processes. Together, the data support the hypothesis that the GABA system is a potential therapeutic target in the modulation of central inflammation.
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Affiliation(s)
- Tadhg Crowley
- Department of Anatomy and Neuroscience, University College Cork, Ireland
| | - John F Cryan
- Department of Anatomy and Neuroscience, University College Cork, Ireland; APC Microbiome Institute, University College Cork, Ireland
| | - Eric J Downer
- School of Medicine, Discipline of Physiology, Trinity Biomedical Sciences Institute, Trinity College, Dublin 2, Ireland.
| | - Olivia F O'Leary
- Department of Anatomy and Neuroscience, University College Cork, Ireland; APC Microbiome Institute, University College Cork, Ireland.
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30
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Bao X, Raguet LL, Cole SM, Howard JD, Gottfried J. The role of piriform associative connections in odor categorization. eLife 2016; 5. [PMID: 27130519 PMCID: PMC4884078 DOI: 10.7554/elife.13732] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Accepted: 04/27/2016] [Indexed: 11/24/2022] Open
Abstract
Distributed neural activity patterns are widely proposed to underlie object identification and categorization in the brain. In the olfactory domain, pattern-based representations of odor objects are encoded in piriform cortex. This region receives both afferent and associative inputs, though their relative contributions to odor perception are poorly understood. Here, we combined a placebo-controlled pharmacological fMRI paradigm with multivariate pattern analyses to test the role of associative connections in sustaining olfactory categorical representations. Administration of baclofen, a GABA(B) agonist known to attenuate piriform associative inputs, interfered with within-category pattern separation in piriform cortex, and the magnitude of this drug-induced change predicted perceptual alterations in fine-odor discrimination performance. Comparatively, baclofen reduced pattern separation between odor categories in orbitofrontal cortex, and impeded within-category generalization in hippocampus. Our findings suggest that odor categorization is a dynamic process concurrently engaging stimulus discrimination and generalization at different stages of olfactory information processing, and highlight the importance of associative networks in maintaining categorical boundaries. DOI:http://dx.doi.org/10.7554/eLife.13732.001 Imagine bringing your groceries home and tucking them into the refrigerator. You’ll probably organize the items by categories: lemons and oranges into the fruit drawer, carrots and cauliflower into the vegetable drawer. Categorization is essential, allowing us to interact with the world in the most efficient way possible. If the differences between objects are not relevant to the task at hand, the brain will group objects together based on their shared properties and develop mental representations of the “categories”. Importantly, we are still aware of the distinctions between objects within the same category. Categories of odor (for example, minty or fruity) are represented in a part of the brain called the olfactory (or piriform) cortex, which receives information from odor cues as well as “top-down” information from other areas of the brain. But how do these top-down pathways influence odor categorization? Bao et al. asked how the brain solves the problem of categorizing odors. For the experiments, human volunteers smelled six familiar odors belonging to three different categories while their brain activity was monitored using a magnetic resonance imaging (fMRI) scanner. Then, half of the participants were given a drug called baclofen that prevents top-down inputs, but not odor cues, from reaching the piriform cortex, while the rest received a placebo. After five days of taking the medication, all of the volunteers had another session of fMRI where they had to categorize the same odors as before. The experiments show that when comparing the fMRI scans before and after the drug treatment, the representations of odors belonging to the same category became more distinct in the piriform cortex in the placebo group. Put differently, as the volunteers were repeatedly exposed to odors of well-known categories, they became better at discriminating individual odors within the same category. However, these changes were disrupted in the group of volunteers that took baclofen. Bao et al.’s findings indicate that this “practice makes perfect” approach to recognizing odors relies on top-down inputs into the piriform cortex. In future work it will be important to study the roles of these inputs in learning new categories of odors, and to investigate whether the mechanisms identified here apply to other sensory information and to more abstract knowledge. DOI:http://dx.doi.org/10.7554/eLife.13732.002
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Affiliation(s)
- Xiaojun Bao
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, United States
| | | | - Sydni M Cole
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, United States
| | - James D Howard
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, United States
| | - Jay Gottfried
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, United States.,Department of Psychology, Northwestern University Weinberg College of Arts and Sciences, Evanston, United States
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31
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Zemoura K, Ralvenius WT, Malherbe P, Benke D. The positive allosteric GABAB receptor modulator rac-BHFF enhances baclofen-mediated analgesia in neuropathic mice. Neuropharmacology 2016; 108:172-8. [PMID: 27108932 DOI: 10.1016/j.neuropharm.2016.04.028] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Revised: 04/01/2016] [Accepted: 04/20/2016] [Indexed: 10/21/2022]
Abstract
Neuropathic pain is associated with impaired inhibitory control of spinal dorsal horn neurons, which are involved in processing pain signals. The metabotropic GABAB receptor is an important component of the inhibitory system and is highly expressed in primary nociceptors and intrinsic dorsal horn neurons to control their excitability. Activation of GABAB receptors with the orthosteric agonist baclofen effectively reliefs neuropathic pain but is associated with severe side effects that prevent its widespread application. The recently developed positive allosteric GABAB receptor modulators lack most of these side effects and are therefore promising drugs for the treatment of pain. Here we tested the high affinity positive allosteric modulator rac-BHFF for its ability to relief neuropathic pain induced by chronic constriction of the sciatic nerve in mice. rac-BHFF significantly increased the paw withdrawal threshold to mechanical stimulation in healthy mice, indicating an endogenous GABABergic tone regulating the sensitivity to mechanical stimuli. Surprisingly, rac-BHFF displayed no analgesic activity in neuropathic mice although GABAB receptor expression was not affected in the dorsal horn as shown by quantitative receptor autoradiography. However, activation of spinal GABAB receptors by intrathecal injection of baclofen reduced hyperalgesia and its analgesic effect was considerably potentiated by co-application of rac-BHFF. These results indicate that under conditions of neuropathic pain the GABAergic tone is too low to provide a basis for allosteric modulation of GABAB receptors. However, allosteric modulators would be well suited as an add-on to reduce the dose of baclofen required to achieve analgesia.
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Affiliation(s)
- Khaled Zemoura
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - William T Ralvenius
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Pari Malherbe
- Discovery Neuroscience, F. Hoffmann-La Roche AG, pRED, Pharma Research & Early Development, Grenzacherstrasse 124, CH4070 Basel, Switzerland
| | - Dietmar Benke
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland; Neuroscience Center Zurich (ZNZ), Winterthurerstrasse 190, CH-8057 Zurich, Switzerland; Drug Discovery Network Zurich (DDNZ), Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
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Abstract
Regulated export of G protein-coupled receptors (GPCRs) from intracellular stores involves chaperones and escort proteins, which promote their progression to the cell surface, and gatekeepers, which retain them in intracellular compartments. Functional γ-aminobutyric acid (GABA)B receptors, the paradigm of this phenomenon, comprise GB1 and GB2 subunits forming a heterodimer. GB1 is retained in the endoplasmic reticulum (ER) in the absence of GB2. A specific ER-resident gatekeeper, prenylated Rab acceptor family 2 (PRAF2), is involved in GB1 retention and prevents its progression into the biosynthetic pathway. GB1 can be released from PRAF2 only on competitive interaction with GB2. PRAF2 is ubiquitous and belongs to a subgroup of the mammalian Ypt-interacting protein (Yip) family. Several other GPCRs are likely to be regulated by Yip proteins, which might be involved in the pathophysiology of human diseases that are associated with impaired receptor targeting to the cell surface.
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Affiliation(s)
- Stéphane Doly
- Institut Cochin, INSERM, CNRS, Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Stefano Marullo
- Institut Cochin, INSERM, CNRS, Université Paris Descartes, Sorbonne Paris Cité, Paris, France.
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Heaney CF, Kinney JW. Role of GABA(B) receptors in learning and memory and neurological disorders. Neurosci Biobehav Rev 2016; 63:1-28. [PMID: 26814961 DOI: 10.1016/j.neubiorev.2016.01.007] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Revised: 12/31/2015] [Accepted: 01/21/2016] [Indexed: 01/13/2023]
Abstract
Although it is evident from the literature that altered GABAB receptor function does affect behavior, these results often do not correspond well. These differences could be due to the task protocol, animal strain, ligand concentration, or timing of administration utilized. Because several clinical populations exhibit learning and memory deficits in addition to altered markers of GABA and the GABAB receptor, it is important to determine whether altered GABAB receptor function is capable of contributing to the deficits. The aim of this review is to examine the effect of altered GABAB receptor function on synaptic plasticity as demonstrated by in vitro data, as well as the effects on performance in learning and memory tasks. Finally, data regarding altered GABA and GABAB receptor markers within clinical populations will be reviewed. Together, the data agree that proper functioning of GABAB receptors is crucial for numerous learning and memory tasks and that targeting this system via pharmaceuticals may benefit several clinical populations.
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Abstract
Over the last few year, antibodies to various central nervous system receptors, particularly the glutamate and γ-aminobutyric acid (GABA) receptors, have been found to be associated with autoimmune neurologic disorders. The receptors include the N-methyl-d-aspartate receptor (NMDAR), the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR), the metabotropic glutamate receptors (mGluRs), and GABA type A and B receptors (respectively GABAAR and GABABR). Compared to the previously described paraneoplastic antibodies directed at intracellular targets, the patients with receptor antibodies are often younger, they less frequently have malignancies, and they respond better to immunotherapy. Many of the patients have limbic encephalitis with amnesia, disorientation, seizures, and psychological or psychiatric symptoms, but those with NMDAR antibodies usually develop a more widespread form of encephalitis, often leading to a decrease in consciousness and requirement for long-term intensive care treatment. The autoantibodies bind directly to the synaptic or extrasynaptic receptors on the membrane surface, and have direct effects on signal transduction in central synapses. These conditions are very important to recognize as the symptoms and complications can be fatal when not treated in time, whereas with immunotherapy many patients recover considerably.
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Affiliation(s)
| | - Maarten J Titulaer
- Department of Neurology, Erasmus University Medical Center, Rotterdam, The Netherlands.
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Wang XX, Jin Y, Luo B, Sun JW, Zhang J, Wang M, Chen L. Sodium salicylate potentiates the GABAB-GIRK pathway to suppress rebound depolarization in neurons of the rat's medial geniculate body. Hear Res 2016; 332:104-12. [PMID: 26688177 DOI: 10.1016/j.heares.2015.11.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Revised: 11/16/2015] [Accepted: 11/23/2015] [Indexed: 12/15/2022]
Abstract
Rebound depolarization (RD) is a voltage response to the offset from pre-hyperpolarization of neuronal membrane potential, which manifests a particular form of the postsynaptic membrane potential response to inhibitory presynaptic inputs. We previously demonstrated that sodium salicylate (NaSal), a tinnitus inducer, can drastically suppress the RD in neurons of rat medial geniculate body (MGB) (Su et al, 2012; PLoS ONE 7, e46969). The purpose of the present study was to investigate the underlying cellular mechanism by using whole-cell patch-clamp recordings in rat MGB slices. NaSal (1.4 mM) had no effects on the current mediated by T-type Ca(2+) channels, indicating that it does not target these channels to suppress the RD. Instead, NaSal was shown to hyperpolarize the resting membrane potential to suppress the RD. NaSal had no effects on the current mediated by hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, indicating that it does not target these channels to hyperpolarize the resting membrane potential. NaSal induced an outward leak current that could be abolished by CGP55845, a GABAB receptor blocker, or respectively by Ba(2+) and Tertiapin-Q, blockers for G-protein-gated inwardly rectifying potassium (GIRK) channels, indicating that NaSal potentiates the GABAB-GIRK pathway to hyperpolarize the resting membrane potential. Our study demonstrates that NaSal targets GABAB receptors to alter functional behaviors of MGB neurons, which may be implicated in NaSal-induced tinnitus.
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Cifuentes-Diaz C, Marullo S, Doly S. Anatomical and ultrastructural study of PRAF2 expression in the mouse central nervous system. Brain Struct Funct 2015; 221:4169-4185. [PMID: 26645984 DOI: 10.1007/s00429-015-1159-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 11/24/2015] [Indexed: 02/01/2023]
Abstract
Prenylated Rab acceptor family, member 2 (PRAF2) is a four transmembrane domain protein of 19 kDa that is highly expressed in particular areas of mammalian brains. PRAF2 is mostly found in the endoplasmic reticulum (ER) of neurons where it plays the role of gatekeeper for the GB1 subunit of the GABAB receptor, preventing its progression in the biosynthetic pathway in the absence of hetero-dimerization with the GB2 subunit. However, PRAF2 can interact with several receptors and immunofluorescence studies indicate that PRAF2 distribution is larger than the ER, suggesting additional biological functions. Here, we conducted an immuno-cytochemical study of PRAF2 distribution in mouse central nervous system (CNS) at anatomical, cellular and ultra-structural levels. PRAF2 appears widely expressed in various regions of mature CNS, such as the olfactory bulbs, cerebral cortex, amygdala, hippocampus, ventral tegmental area and spinal cord. Consistent with its regulatory role of GABAB receptors, PRAF2 was particularly abundant in brain regions known to express GB1 subunits. However, other brain areas where GB1 is expressed, such as basal ganglia, thalamus and hypothalamus, contain little or no PRAF2. In these areas, GB1 subunits might reach the cell surface of neurons independently of GB2 to exert biological functions distinct from those of GABAB receptors, or be regulated by other gatekeepers. Electron microscopy studies confirmed the localization of PRAF2 in the ER, but identified previously unappreciated localizations, in mitochondria, primary cilia and sub-synaptic region. These data indicate additional modes of GABAB regulation in specific brain areas and new biological functions of PRAF2.
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Affiliation(s)
- Carmen Cifuentes-Diaz
- Institut du Fer à Moulin, INSERM UMR-S839, Université Pierre et Marie Curie, 75005, Paris, France
| | - Stefano Marullo
- Institut Cochin, INSERM U1016, CNRS UMR8104, Université Paris Descartes, Sorbonne Paris Cité, 27 rue du Faubourg St-Jacques, 75014, Paris, France
| | - Stéphane Doly
- Institut Cochin, INSERM U1016, CNRS UMR8104, Université Paris Descartes, Sorbonne Paris Cité, 27 rue du Faubourg St-Jacques, 75014, Paris, France.
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Kasten CR, Boehm SL. Identifying the role of pre-and postsynaptic GABA(B) receptors in behavior. Neurosci Biobehav Rev 2015; 57:70-87. [PMID: 26283074 DOI: 10.1016/j.neubiorev.2015.08.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Revised: 06/18/2015] [Accepted: 08/09/2015] [Indexed: 12/15/2022]
Abstract
Although many reviews exist characterizing the molecular differences of GABAB receptor isoforms, there is no current review of the in vivo effects of these isoforms. The current review focuses on whether the GABAB1a and GABAB1b isoforms contribute differentially to behaviors in isoform knockout mice. The roles of these receptors have primarily been characterized in cognitive, anxiety, and depressive phenotypes. Currently, the field supports a role of GABAB1a in memory maintenance and protection against an anhedonic phenotype, whereas GABAB1b appears to be involved in memory formation and a susceptibility to developing an anhedonic phenotype. Although GABAB receptors have been strongly implicated in drug abuse phenotypes, no isoform-specific work has been done in this field. Future directions include developing site-specific isoform knockdown to identify the role of different brain regions in behavior, as well as identifying how these isoforms are involved in development of behavioral phenotypes.
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Affiliation(s)
- Chelsea R Kasten
- Department of Psychology, Indianapolis University Purdue University-Indianapolis, 402N Blackford St LD 124, Indianapolis, IN 46202, United States.
| | - Stephen L Boehm
- Department of Psychology, Indianapolis University Purdue University-Indianapolis, 402N Blackford St LD 124, Indianapolis, IN 46202, United States; Indiana Alcohol Research Center, 545 Barnhill Drive EH 317, Indianapolis, IN, United States.
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Keegan BMT, Beveridge TJR, Pezor JJ, Xiao R, Sexton T, Childers SR, Howlett AC. Chronic baclofen desensitizes GABA(B)-mediated G-protein activation and stimulates phosphorylation of kinases in mesocorticolimbic rat brain. Neuropharmacology 2015; 95:492-502. [PMID: 25724082 PMCID: PMC4537290 DOI: 10.1016/j.neuropharm.2015.02.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Revised: 12/30/2014] [Accepted: 02/11/2015] [Indexed: 01/19/2023]
Abstract
The GABAB receptor is a therapeutic target for CNS and neuropathic disorders; however, few preclinical studies have explored effects of chronic stimulation. This study evaluated acute and chronic baclofen treatments on GABAB-activated G-proteins and signaling protein phosphorylation as indicators of GABAB signaling capacity. Brain sections from rats acutely administered baclofen (5 mg/kg, i.p.) showed no significant differences from controls in GABAB-stimulated GTPγS binding in any brain region, but displayed significantly greater phosphorylation/activation of focal adhesion kinase (pFAK(Tyr397)) in mesocorticolimbic regions (caudate putamen, cortex, hippocampus, thalamus) and elevated phosphorylated/activated glycogen synthase kinase 3-β (pGSK3β(Tyr216)) in the prefrontal cortex, cerebral cortex, caudate putamen, nucleus accumbens, thalamus, septum, and globus pallidus. In rats administered chronic baclofen (5 mg/kg, t.i.d. for five days), GABAB-stimulated GTPγS binding was significantly diminished in the prefrontal cortex, septum, amygdala, and parabrachial nucleus compared to controls. This effect was specific to GABAB receptors: there was no effect of chronic baclofen treatment on adenosine A1-stimulated GTPγS binding in any region. Chronically-treated rats also exhibited increases in pFAK(Tyr397) and pGSK3β(Tyr216) compared to controls, and displayed wide-spread elevations in phosphorylated dopamine- and cAMP-regulated phosphoprotein-32 (pDARPP-32(Thr34)) compared to acutely-treated or control rats. We postulate that those neuroadaptive effects of GABAB stimulation mediated by G-proteins and their sequelae correlate with tolerance to several of baclofen's effects, whereas sustained signaling via kinase cascades points to cross-talk between GABAB receptors and alternative mechanisms that are resistant to desensitization. Both desensitized and sustained signaling pathways should be considered in the development of pharmacotherapies targeting the GABA system.
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Affiliation(s)
- Bradley M T Keegan
- Center for the Neurobiology of Addiction Treatment, Winston-Salem, NC 27157, USA; Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
| | - Thomas J R Beveridge
- Center for the Neurobiology of Addiction Treatment, Winston-Salem, NC 27157, USA; Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
| | - Jeffrey J Pezor
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA; Department of Chemistry, Wake Forest University, Winston-Salem, NC 27157, USA
| | - Ruoyu Xiao
- Center for the Neurobiology of Addiction Treatment, Winston-Salem, NC 27157, USA; Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
| | - Tammy Sexton
- Center for the Neurobiology of Addiction Treatment, Winston-Salem, NC 27157, USA; Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
| | - Steven R Childers
- Center for the Neurobiology of Addiction Treatment, Winston-Salem, NC 27157, USA; Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
| | - Allyn C Howlett
- Center for the Neurobiology of Addiction Treatment, Winston-Salem, NC 27157, USA; Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA.
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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: 126] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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Li X, Kaczanowska K, Finn MG, Markou A, Risbrough VB. The GABA(B) receptor positive modulator BHF177 attenuated anxiety, but not conditioned fear, in rats. Neuropharmacology 2015; 97:357-64. [PMID: 26002628 DOI: 10.1016/j.neuropharm.2015.05.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Revised: 04/27/2015] [Accepted: 05/02/2015] [Indexed: 01/25/2023]
Abstract
GABAB (γ-aminobutyric acid B) receptors may be a therapeutic target for anxiety disorders. Here we characterized the effects of the GABAB receptor positive allosteric modulator (PAM) BHF177 on conditioned and unconditioned physiological responses to threat in the light-enhanced startle (LES), stress-induced hyperthermia, and fear-potentiated startle (FPS) procedures in rats. The effects of BHF177 on LES were compared with those of the GABAB receptor agonists baclofen and CGP44532, and the positive control buspirone, a 5-HT1A receptor partial agonist with anxiolytic activity in humans. Baclofen (0.4, 0.9 and 1.25 mg/kg) and CGP44532 (0.065, 0.125 and 0.25 mg/kg) administration had significant sedative, but not anxiolytic, activity reflected in overall decrease in the startle response in the LES tests. BHF177 (10, 20 and 40 mg/kg) had no effect on LES, nor did it produce an overall sedative effect. Interesting, however, when rats were grouped by high and low LES responses, BHF177 had anxiolytic-like effects only on LES in high, but not low, LES responding rats. BHF177 also blocked stress-induced hyperthermia, but had no effect on conditioned fear responses in the FPS test. Buspirone (1 and 3 mg/kg) had an anxiolytic-like profile in both LES and FPS tests. These results indicate that BHF177 may specifically attenuate unconditioned anxiety in individuals that exhibit a high anxiety state, and has fewer sedative effects than direct agonists. Thus, BHF177 or other GABAB receptor PAMs may be promising compounds for alleviating increased anxiety seen in various psychiatric disorders with a superior side-effect profile compared to GABAB receptor agonists.
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Barati MT, Scherzer J, Wu R, Rane MJ, Klein JB. Cytoskeletal rearrangement and Src and PI-3K-dependent Akt activation control GABA(B)R-mediated chemotaxis. Cell Signal 2015; 27:1178-85. [PMID: 25725285 DOI: 10.1016/j.cellsig.2015.02.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Revised: 02/01/2015] [Accepted: 02/15/2015] [Indexed: 01/13/2023]
Abstract
The γ-amino butyric acid (GABA) type B receptors (GABA(B)R) function as chemoattractant receptors in response to GABA(B)R agonists in human neutrophils. The goal of this study was to define signaling mechanisms regulating GABA(B)R-mediated chemotaxis and cytoskeletal rearrangement. In a proteomic study we identified serine/threonine kinase Akt, tyrosine kinases Src and Pyk2, microtubule regulator kinesin and microtubule affinity-regulating kinase (MARK) co-immunoprecipitating with GABA(B)R. To define the contributions of these candidate signaling events in GABA(B)R-mediated chemotaxis, we used rat basophilic leukemic cells (RBL-2H3 cells) stably transfected with human GABA(B1b) and GABA(B2) receptors. The GABA(B)R agonist baclofen induced Akt phosphorylation and chemotaxis by binding to its specific GABA(B)R since pretreatment of cells with CGP52432, a GABA(B)R antagonist, blocked such effects. Moreover, baclofen induced Akt phosphorylation was shown to be dependent upon PI-3K and Src kinases. Baclofen failed to stimulate actin polymerization in suspended RBL cells unless exposed to a baclofen gradient. However, baclofen stimulated both actin and tubulin polymerization in adherent RBL-GABA(B)R cells. Blockade of actin and tubulin polymerization by treatment of cells with cytochalasin D or nocodazole respectively, abolished baclofen-mediated chemotaxis. Furthermore, baclofen stimulated Pyk2 and STAT3 phosphorylation, both known regulators of cell migration. In conclusion, GABA(B)R stimulation promotes chemotaxis in RBL cells which is dependent on signaling via PI3-K/Akt, Src kinases and on rearrangement of both microtubules and actin cytoskeleton. These data define mechanisms of GABA(B)R-mediated chemotaxis which may potentially be used to therapeutically regulate cellular response to injury and disease.
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Abstract
G protein-gated inwardly rectifying K(+) (GIRK/K(ir)3) channels are critical to brain function. They hyperpolarize neurons in response to activation of different G protein-coupled receptors, reducing cell excitability. Molecular cloning has revealed four distinct mammalian genes (GIRK1-4), which, with the exception of GIRK4, are broadly expressed in the central nervous system (CNS) and have been implicated in a variety of neurological disorders. Although the molecular structure and composition of GIRK channels are key determinants of their biophysical properties, their cellular and subcellular localization patterns and densities on the neuronal surface are just as important to nerve function. Current data obtained with high-resolution quantitative localization techniques reveal complex, subcellular compartment-specific distribution patterns of GIRK channel subunits. Recent efforts have focused on determining the associated proteins that form macromolecular complexes with GIRK channels. Demonstration of the precise subcellular compartmentalization of GIRK channels and their associated proteins represents a crucial step in understanding the contribution of these channels to specific aspects of neuronal function under both physiological and pathological conditions. Here, we present an overview of studies aimed at determining the cellular and subcellular localization of GIRK channel subunits in mammalian brain neurons and discuss implications for neuronal physiology.
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Affiliation(s)
- Rafael Luján
- Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, Albacete, Spain.
| | - Carolina Aguado
- Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, Albacete, Spain
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43
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Takeda M, Nasu M, Kanazawa T, Shimazu Y. Activation of GABA(B) receptors potentiates inward rectifying potassium currents in satellite glial cells from rat trigeminal ganglia: in vivo patch-clamp analysis. Neuroscience 2015; 288:51-8. [PMID: 25542421 DOI: 10.1016/j.neuroscience.2014.12.024] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Revised: 12/15/2014] [Accepted: 12/15/2014] [Indexed: 11/23/2022]
Abstract
In a previous study, we demonstrated that inflammation suppressed inward rectifying K(+) (Kir) currents in satellite glial cells (SGCs) from the trigeminal ganglia (TRGs) and that this impairment of glial potassium homeostasis in the trigeminal ganglion (TRG) contributed to trigeminal pain. The aim of the present study was to investigate whether activation of GABAB receptors modulates the Kir current in SGCs using in vivo patch-clamp and immunohistochemical techniques. Immunohistochemically, we found that immunoreactivity for glial-specific Kir channel subunit Kir4.1 and the GABAB receptor was co-expressed in SGCs from the TRGs. In vivo whole-cell recordings were made using SGCs from the TRGs of urethane-anesthetized rats. Application of baclofen, a GABAB receptor agonist, significantly increased the mean peak amplitude of Kir currents in a concentration-dependent and reversible manner. Baclofen-induced potentiation of the Kir current was abolished by co-application of 3-amino-2-(4-chlorophenyl)-2-hydroxyprophylsulfonic acid (saclofen). In addition, baclofen significantly potentiated the density of the Ba(2+)-sensitive Kir current, and resulted in hyperpolarization of the mean membrane potential. These results suggest that activation of GABAB receptors potentiates the Kir current in SGCs and that GABA released from the TRG neuronal soma could contribute to buffering of extracellular K(+) concentrations following excitation of TRG neurons during the processing of sensory information, including the transmission of noxious stimuli.
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Varani AP, Pedrón VT, Machado LM, Antonelli MC, Bettler B, Balerio GN. Lack of GABAB receptors modifies behavioural and biochemical alterations induced by precipitated nicotine withdrawal. Neuropharmacology 2014; 90:90-101. [PMID: 25479464 DOI: 10.1016/j.neuropharm.2014.11.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Revised: 11/19/2014] [Accepted: 11/22/2014] [Indexed: 01/09/2023]
Abstract
The nicotine (NIC) withdrawal syndrome is considered to be a major cause of the high relapse rate among individuals undergoing smoking cessation. The aim of the present study was to evaluate a possible role of GABAB receptors in NIC withdrawal, by comparing GABAB1 knockout mice and their wild-type littermates. We analysed the time course of the global withdrawal score, the anxiety-like effects, monoamine concentrations, the brain-derived neurotrophic factor (BDNF) expression, the corticosterone plasmatic levels and [(3)H]epibatidine binding sites during NIC withdrawal precipitated by mecamylamine, a nicotinic receptor antagonist (MEC). In NIC withdrawn wild-type mice, we observed a global withdrawal score, an anxiety-like effect in the elevated plus maze, a decrease of the striatal dopamine and 3,4-dihydroxyphenylacetic acid concentrations, an increase of corticosterone plasma levels, a reduction of BDNF expression in several brain areas and an increase of [(3)H]epibatidine binding sites in specific brain regions. Interestingly, the effects found in NIC withdrawn wild-type mice were absent in GABAB1 knockout mice, suggesting that GABAB1 subunit of the GABAB receptor is involved in the regulation of the behavioural and biochemical alterations induced by NIC withdrawal in mice. These results reveal an interaction between the GABAB receptors and the neurochemical systems through which NIC exerts its long-term effects.
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Affiliation(s)
- Andrés P Varani
- Instituto de Investigaciones Farmacológicas (CONICET), Junín 956, 5° Piso, Buenos Aires C1113AAD, Argentina
| | - Valeria T Pedrón
- Instituto de Investigaciones Farmacológicas (CONICET), Junín 956, 5° Piso, Buenos Aires C1113AAD, Argentina
| | - Lirane Moutinho Machado
- Instituto de Investigaciones Farmacológicas (CONICET), Junín 956, 5° Piso, Buenos Aires C1113AAD, Argentina
| | - Marta C Antonelli
- Instituto de Química y Fisicoquímica Biológicas (UBA-CONICET), Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Bernhard Bettler
- Department of Biomedicine, Institute of Physiology, Pharmazentrum, University of Basel, Klingelbergstrasse 50/70, CH-4056 Basel, Switzerland
| | - Graciela N Balerio
- Instituto de Investigaciones Farmacológicas (CONICET), Junín 956, 5° Piso, Buenos Aires C1113AAD, Argentina; Cátedra de Farmacología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, 5° Piso, Buenos Aires C1113AAD, Argentina.
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Ort A, Kometer M, Rohde J, Seifritz E, Vollenweider FX. The role of GABAB receptors in human reinforcement learning. Eur Neuropsychopharmacol 2014; 24:1606-14. [PMID: 25194227 DOI: 10.1016/j.euroneuro.2014.08.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Revised: 07/30/2014] [Accepted: 08/16/2014] [Indexed: 11/23/2022]
Abstract
Behavioral evidence from human studies suggests that the γ-aminobutyric acid type B receptor (GABAB receptor) agonist baclofen modulates reinforcement learning and reduces craving in patients with addiction spectrum disorders. However, in contrast to the well established role of dopamine in reinforcement learning, the mechanisms by which the GABAB receptor influences reinforcement learning in humans remain completely unknown. To further elucidate this issue, a cross-over, double-blind, placebo-controlled study was performed in healthy human subjects (N=15) to test the effects of baclofen (20 and 50mg p.o.) on probabilistic reinforcement learning. Outcomes were the feedback-induced P2 component of the event-related potential, the feedback-related negativity, and the P300 component of the event-related potential. Baclofen produced a reduction of P2 amplitude over the course of the experiment, but did not modulate the feedback-related negativity. Furthermore, there was a trend towards increased learning after baclofen administration relative to placebo over the course of the experiment. The present results extend previous theories of reinforcement learning, which focus on the importance of mesolimbic dopamine signaling, and indicate that stimulation of cortical GABAB receptors in a fronto-parietal network leads to better attentional allocation in reinforcement learning. This observation is a first step in our understanding of how baclofen may improve reinforcement learning in healthy subjects. Further studies with bigger sample sizes are needed to corroborate this conclusion and furthermore, test this effect in patients with addiction spectrum disorder.
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Blankenburg S, Balfanz S, Hayashi Y, Shigenobu S, Miura T, Baumann O, Baumann A, Blenau W. Cockroach GABAB receptor subtypes: molecular characterization, pharmacological properties and tissue distribution. Neuropharmacology 2014; 88:134-44. [PMID: 25242738 DOI: 10.1016/j.neuropharm.2014.08.022] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Revised: 08/10/2014] [Accepted: 08/23/2014] [Indexed: 11/29/2022]
Abstract
γ-aminobutyric acid (GABA) is the predominant inhibitory neurotransmitter in the central nervous system (CNS). Its effects are mediated by either ionotropic GABAA receptors or metabotropic GABAB receptors. GABAB receptors regulate, via Gi/o G-proteins, ion channels, and adenylyl cyclases. In humans, GABAB receptor subtypes are involved in the etiology of neurologic and psychiatric disorders. In arthropods, however, these members of the G-protein-coupled receptor family are only inadequately characterized. Interestingly, physiological data have revealed important functions of GABAB receptors in the American cockroach, Periplaneta americana. We have cloned cDNAs coding for putative GABAB receptor subtypes 1 and 2 of P. americana (PeaGB1 and PeaGB2). When both receptor proteins are co-expressed in mammalian cells, activation of the receptor heteromer with GABA leads to a dose-dependent decrease in cAMP production. The pharmacological profile differs from that of mammalian and Drosophila GABAB receptors. Western blot analyses with polyclonal antibodies have revealed the expression of PeaGB1 and PeaGB2 in the CNS of the American cockroach. In addition to the widespread distribution in the brain, PeaGB1 is expressed in salivary glands and male accessory glands. Notably, PeaGB1-like immunoreactivity has been detected in the GABAergic salivary neuron 2, suggesting that GABAB receptors act as autoreceptors in this neuron.
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Affiliation(s)
- S Blankenburg
- Institute of Biochemistry and Biology, Department of Animal Physiology, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam, Germany.
| | - S Balfanz
- Institute of Complex Systems, Zelluläre Biophysik (ICS-4), Research Center Jülich, Forschungszentrum Jülich, 52425, Jülich, Germany.
| | - Y Hayashi
- Laboratory of Ecological Genetics, Graduate School of Environmental Science, Hokkaido University, Sapporo, Hokkaido, 060-0810, Japan.
| | - S Shigenobu
- NIBB Core Research Facilities, National Institute for Basic Biology, National Institutes of Natural Sciences, Okazaki, 444-8585, Japan.
| | - T Miura
- Laboratory of Ecological Genetics, Graduate School of Environmental Science, Hokkaido University, Sapporo, Hokkaido, 060-0810, Japan.
| | - O Baumann
- Institute of Biochemistry and Biology, Department of Animal Physiology, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam, Germany.
| | - A Baumann
- Institute of Complex Systems, Zelluläre Biophysik (ICS-4), Research Center Jülich, Forschungszentrum Jülich, 52425, Jülich, Germany.
| | - W Blenau
- Institut für Bienenkunde, Polytechnische Gesellschaft, Goethe-Universität Frankfurt am Main, FB Biowissenschaften, Karl-von-Frisch-Weg 2, 61440, Oberursel, Germany.
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Cheng ZY, Wang XP, Schmid KL, Han XG. GABAB1 and GABAB2 receptor subunits co-expressed in cultured human RPE cells regulate intracellular Ca2+ via Gi/o-protein and phospholipase C pathways. Neuroscience 2014; 280:254-61. [PMID: 25241062 DOI: 10.1016/j.neuroscience.2014.09.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 09/10/2014] [Accepted: 09/10/2014] [Indexed: 11/26/2022]
Abstract
GABAB receptors associate with Gi/o-proteins that regulate voltage-gated Ca(2+) channels and thus the intracellular Ca(2+) concentration ([Ca(2+)]i), there is also reported cross-regulation of phospholipase C. These associations have been studied extensively in the brain and also shown to occur in non-neural cells (e.g. human airway smooth muscle). More recently GABAB receptors have been observed in chick retinal pigment epithelium (RPE). The aims were to investigate whether the GABAB receptor subunits, GABAB1 and GABAB2, are co-expressed in cultured human RPE cells, and then determine if the GABAB receptor similarly regulates the [Ca(2+)]i of RPE cells and if phospholipase C is involved. Human RPE cells were cultured from five donor eye cups. Evidence for GABAB1 and GABAB2 mRNAs and proteins in the RPE cell cultures was investigated using real time polymerase chain reaction, western blots and immunofluorescence. The effects of the GABAB receptor agonist baclofen, antagonist CGP46381, a Gi/o-protein inhibitor pertussis toxin, and the phospholipase C inhibitor U73122 on [Ca(2+)]i in cultured human RPE were demonstrated using Fluo-3. Both GABAB1 and GABAB2 mRNA and protein were identified in cell cultures of human RPE; antibody staining was co-localized to the cell membrane and cytoplasm. One-hundred micromolars of baclofen caused a transient increase in the [Ca(2+)]i of RPE cells regardless of whether Ca(2+) was added to the buffer. Baclofen-induced increases in the [Ca(2+)]i were attenuated by pre-treatment with CGP46381, pertussis toxin, and U73122. GABAB1 and GABAB2 are co-expressed in cell cultures of human RPE. GABAB receptors in RPE regulate the [Ca(2+)]i via a Gi/o-protein and phospholipase C pathway.
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Affiliation(s)
- Z-Y Cheng
- Department of Ophthalmology, Qilu Hospital, Shandong University, Jinan, Shandong 250012, China.
| | - X-P Wang
- The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Qilu Hospital, Shandong University, Jinan, Shandong 250012, China
| | - K L Schmid
- School of Optometry and Vision Science, Faculty of Health, and Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD 4059, Australia
| | - X-G Han
- Department of Ophthalmology, The Second Hospital, Jinan, Shandong 250001, China
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Kasten CR, Boehm SL. Intra-nucleus accumbens shell injections of R(+)- and S(-)-baclofen bidirectionally alter binge-like ethanol, but not saccharin, intake in C57Bl/6J mice. Behav Brain Res 2014; 272:238-47. [PMID: 25026094 DOI: 10.1016/j.bbr.2014.07.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Revised: 07/03/2014] [Accepted: 07/07/2014] [Indexed: 10/25/2022]
Abstract
The GABAB agonist baclofen has been widely researched clinically and preclinically as a treatment of alcohol use disorders (AUDs). However, the efficacy of baclofen remains uncertain. The clinically used racemic compound can be separated into separate enantiomers. These enantiomers have produced different profiles in behavioral assays, with the S- compound often being ineffective compared to the R- compound, or the S- compound antagonizing the effects of the R- compound. We have previously demonstrated that the R(+)-baclofen enantiomer decreases binge-like ethanol intake in the Drinking-in-the-Dark (DID) paradigm, whereas the S(-)-baclofen enantiomer increases ethanol intake. One area implicated in drug abuse is the nucleus accumbens shell (NACsh).The current study sought to define the role of the NACsh in the enantioselective effects of baclofen on binge-like ethanol consumption by directly microinjecting each enantiomer into the structure. Following bilateral cannulation of the NACsh, C57Bl/6J mice were given 5 days of access to ethanol or saccharin for 2h, 3h into the dark cycle. On Day 5 mice were given an injection of aCSF, 0.02 R(+)-, 0.04R(+)-, 0.08 S(-)-, or 0.16 S(-)-baclofen (μg/side dissolved in 200nl of aCSF). It was found that the R(+)-baclofen dose-dependently decreased ethanol consumption, whereas the high S(-)-baclofen dose increased ethanol consumption, compared to the aCSF group. Saccharin consumption was not affected. These results further confirm that GABAB receptors and the NACsh shell are integral in mediating ethanol intake. They also demonstrate that baclofen displays bidirectional, enantioselective effects which are important when considering therapeutic uses of the drug.
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Affiliation(s)
- Chelsea R Kasten
- Department of Psychology, Indiana University Purdue University-Indianapolis, 402 N Blackford St LD 124 Indianapolis, IN 46202, USA.
| | - Stephen L Boehm
- Department of Psychology, Indiana University Purdue University-Indianapolis, 402 N Blackford St LD 124 Indianapolis, IN 46202, USA; Indiana Alcohol Research Center, 545 Barnhill Drive EH 317 Indianapolis, IN, USA
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McClure-Begley TD, Grady SR, Marks MJ, Collins AC, Stitzel JA. Presynaptic GABAB autoreceptor regulation of nicotinic acetylcholine receptor mediated [(3)H]-GABA release from mouse synaptosomes. Biochem Pharmacol 2014; 91:87-96. [PMID: 24953818 DOI: 10.1016/j.bcp.2014.06.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Revised: 06/06/2014] [Accepted: 06/12/2014] [Indexed: 01/26/2023]
Abstract
Activation of nicotinic acetylcholine receptors (nAChRs) can elicit neurotransmitter release from presynaptic nerve terminals. Mechanisms contributing to cell-and-terminal specific regulation of nAChR-mediated neurotransmitter exocytosis are not fully understood. The experiments discussed here examine how activation of GABAB auto- and hetero-receptors suppress nAChR-mediated release of [(3)H]-GABA and [(3)H]-dopamine ((3)H-DA) from mouse striatal synaptosomes. Activation of presynaptic GABAB receptors with (R)-baclofen decreased both [(3)H]-GABA and [(3)H]-DA release evoked by potassium depolarization. However, when nAChRs were activated with ACh to evoke neurotransmitter release, (R)-baclofen had no effect on [(3)H]-DA release, but potently inhibited ACh-evoked [(3)H]-GABA release. Inhibition of nAChR-evoked [(3)H]-GABA release by (R)-baclofen was time sensitive and the effect was lost after prolonged exposure to the GABAB agonist. The early inhibitory effect of GABAB activation on ACh-evoked [(3)H]-GABA release was partially attenuated by antagonists of the phosphatase, calcineurin. Furthermore, antagonists of protein kinase C (PKC) prevented the time-dependent loss of the inhibitory (R)-baclofen effect on [(3)H]-GABA release. These results suggest that α4β2*-nAChRs present on GABAergic nerve terminals in the striatum are subject to functional regulation by GABAB autoreceptors that is apparently cell-type specific, since it is absent from DAergic striatal nerve terminals. In addition, the functional modulation of α4β2*-type nAChRs on striatal GABAergic nerve terminals by GABAB autoreceptor activation is time-sensitive and appears to involve opposing actions of calcineurin and PKC.
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Affiliation(s)
- Tristan D McClure-Begley
- Institute for Behavioral Genetics, University of Colorado, Boulder, CO, United States of America; Department of Integrative Physiology, University of Colorado, Boulder, CO, United States of America; Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO, United States of America
| | - Sharon R Grady
- Institute for Behavioral Genetics, University of Colorado, Boulder, CO, United States of America
| | - Michael J Marks
- Institute for Behavioral Genetics, University of Colorado, Boulder, CO, United States of America; Department of Psychology and Neuroscience, University of Colorado, Boulder, CO, United States of America
| | - Allan C Collins
- Institute for Behavioral Genetics, University of Colorado, Boulder, CO, United States of America
| | - Jerry A Stitzel
- Institute for Behavioral Genetics, University of Colorado, Boulder, CO, United States of America; Department of Integrative Physiology, University of Colorado, Boulder, CO, United States of America.
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Bai HP, Liu P, Wu YM, Guo WY, Guo YX, Wang XL. Activation of spinal GABAB receptors normalizes N-methyl-D-aspartate receptor in diabetic neuropathy. J Neurol Sci 2014; 341:68-72. [PMID: 24787504 DOI: 10.1016/j.jns.2014.04.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Revised: 03/16/2014] [Accepted: 04/01/2014] [Indexed: 12/13/2022]
Abstract
N-methyl-D-aspartate receptor (NMDAR) activity is increased, while GABAB receptor is downregulated in the spinal cord dorsal horn in diabetic neuropathy. In this study, we determined the interaction of NMDARs and GABAB receptors in streptozotocin (STZ)-induced diabetic neuropathy. The paw withdrawal threshold (PWT) was significantly lower in STZ-treated rats than in vehicle-treated rats. Intrathecal injection of baclofen, a GABAB receptor agonist, significantly increased the PWT in STZ-treated rats, an effect that was abolished by pre-administration of the GABAB receptor specific antagonist CGP55845. Spinal NR2B, an NMDA receptor subunit, protein and mRNA expression levels were significantly higher in STZ-treated rats than in vehicle-treated rats. Intrathecal baclofen significantly reduced the NR2B protein and mRNA expression levels in STZ-treated rats. Intrathecal administration of CGP55845 eliminated baclofen-induced reduction of NR2B protein and mRNA levels in STZ-treated rats. In addition, the phosphorylated cAMP response element-binding (CREB) protein level was significantly higher in the spinal cord dorsal horn in STZ-treated rats compared with vehicle-treated rats. Intrathecal injection of baclofen significantly decreased phosphorylated CREB protein level in STZ-treated rats; an effect was blocked by CGP55845. These data suggest that activation of GABAB receptors in the spinal cord dorsal horn normalizes NMDAR expression level in diabetic neuropathic pain.
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Affiliation(s)
- Hui-Ping Bai
- Department of Anesthesiology, The Third Hospital of Hebei Medical University, China
| | - Peng Liu
- Department of Anesthesiology, The Third Hospital of Hebei Medical University, China
| | - Yu-Ming Wu
- Department of Physiology, Hebei Medical University, China
| | - Wen-Ya Guo
- Department of Anesthesiology, The Third Hospital of Hebei Medical University, China
| | - Yue-Xian Guo
- Department of Urology, The Third Hospital of Hebei Medical University, China
| | - Xiu-Li Wang
- Department of Anesthesiology, The Third Hospital of Hebei Medical University, China.
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