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Krámos B, Hadady Z, Makó A, Szántó G, Felföldi N, Magdó I, Bobok AÁ, Bata I, Román V, Visegrády A, Keserű G, Greiner I, Éles J. Novel-Type GABA B PAMs: Structure-Activity Relationship in Light of the Protein Structure. ACS Med Chem Lett 2024; 15:396-405. [PMID: 38505850 PMCID: PMC10945541 DOI: 10.1021/acsmedchemlett.3c00560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 02/16/2024] [Accepted: 02/20/2024] [Indexed: 03/21/2024] Open
Abstract
Selecting a known HTS hit with the pyrazolo[1,5-a]pyrimidine core, our project was started from CMPPE, and its optimization was driven by a ligand-based pharmacophore model developed on the basis of published GABAB positive allosteric modulators (PAMs). Our primary goal was to improve the potency by finding new enthalpic interactions. Therefore, we included the lipophilic ligand efficiency (LLE or LipE) as an objective function in the optimization that led to a carboxylic acid derivative (34). This lead candidate offers the possibility to improve potency without drastically inflating the physicochemical properties. Although the discovery of the novel carboxyl feature was surprising, it turned out to be an important element of the GABAB PAM pharmacophore that can be perfectly explained based on the new protein structures. Rationalizing the binding mode of 34, we analyzed the intersubunit PAM binding site of GABAB receptor using the publicly available experimental structures.
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Affiliation(s)
- Balázs Krámos
- Spectroscopic
Research Department, Gedeon Richter Plc., Gyömrői út
19-21, Budapest, 1103 Hungary
| | - Zsuzsa Hadady
- Chemistry
Department, Gedeon Richter Plc., Gyömrői út
19-21, Budapest, 1103 Hungary
| | - Attila Makó
- Chemistry
Department, Gedeon Richter Plc., Gyömrői út
19-21, Budapest, 1103 Hungary
| | - Gábor Szántó
- Chemistry
Department, Gedeon Richter Plc., Gyömrői út
19-21, Budapest, 1103 Hungary
| | - Nóra Felföldi
- Chemistry
Department, Gedeon Richter Plc., Gyömrői út
19-21, Budapest, 1103 Hungary
| | - Ildikó Magdó
- Spectroscopic
Research Department, Gedeon Richter Plc., Gyömrői út
19-21, Budapest, 1103 Hungary
| | - Amrita Ágnes Bobok
- Pharmacological
and Drug Safety Research, Gedeon Richter
Plc., Gyömrői
út 19-21, Budapest, 1103 Hungary
| | - Imre Bata
- Chemistry
Department, Gedeon Richter Plc., Gyömrői út
19-21, Budapest, 1103 Hungary
| | - Viktor Román
- Pharmacological
and Drug Safety Research, Gedeon Richter
Plc., Gyömrői
út 19-21, Budapest, 1103 Hungary
| | - András Visegrády
- Pharmacological
and Drug Safety Research, Gedeon Richter
Plc., Gyömrői
út 19-21, Budapest, 1103 Hungary
| | - György
M. Keserű
- Medicinal
Chemistry Research Group, Research Centre
for Natural Sciences, Magyar tudósok krt. 2, Budapest, 1117 Hungary
| | - István Greiner
- Research
and Development Director, Gedeon Richter
Plc., Gyömrői
út 19-21, Budapest, 1103 Hungary
| | - János Éles
- Head
of Medicinal Chemistry, Gedeon Richter Plc., Gyömrői út
19-21, Budapest, 1103 Hungary
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Ghenaatgar-Kasbi M, Rezaei M, Moharreri P, Heidarian Miri H, Sazegar G, Haghir H. The effect of maternal diabetes on the expression of gamma-aminobutyric acid and metabotropic glutamate receptors in male newborn rats' inferior colliculi. J Perinat Med 2023; 51:940-949. [PMID: 37139647 DOI: 10.1515/jpm-2022-0553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Accepted: 02/28/2023] [Indexed: 05/05/2023]
Abstract
OBJECTIVES Few studies have examined the molecular alterations in the auditory pathway of infants of diabetic mothers, notwithstanding the fact that maternal diabetes may have an impact on the development of the neonatal peripheral and central nervous systems. Male newborn rats were studied to determine how maternal diabetes affected the expression of gamma-aminobutyric acid (GABAAα1 and GABAB1) and metabotropic glutamate (mGlu2) receptors in the inferior colliculus (IC) in this research. METHODS Female rats were given a single intraperitoneal injection of streptozotocin (STZ) at a 65 mg/kg dose to develop a model of diabetic mothers. The study population was split into sham, diabetes without treatment, and diabetes with insulin groups. Their male neonatal rats were anesthetized on P0, P7, and P14 after mating and delivery. The receptors' distribution pattern was studied using immunohistochemistry (IHC). RESULTS Pairwise comparison in the groups revealed that the GABA receptors (Aα1 and B1) were significantly downregulated in the diabetes without treatment group (p<0.001). Furthermore, pairwise comparison in the groups indicated significant mGlu2 upregulation in the diabetes without treatment group (p<0.001). Regarding the concentration of all receptors, there was no discernible distinction between the diabetes with insulin and sham groups. CONCLUSIONS This investigation showed that the concentration of GABAAα1 and GABAB1 receptors decreased significantly over time, whereas the concentration of mGlu2 receptors increased significantly over time in male neonatal rats born to streptozotocin-induced diabetic mothers.
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Affiliation(s)
- Maryam Ghenaatgar-Kasbi
- Department of Anatomy and Cell Biology, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Mohammad Rezaei
- Department of Physiology, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Payam Moharreri
- Department of Anatomy and Cell Biology, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Hamid Heidarian Miri
- Social Determinants of Health Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Ghasem Sazegar
- Department of Anatomy and Cell Biology, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Hossein Haghir
- Department of Anatomy and Cell Biology, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
- Medical Genetic Research Center (MGRC), School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
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Tureček R, Melichar A, Králíková M, Hrušková B. The role of GABA B receptors in the subcortical pathways of the mammalian auditory system. Front Endocrinol (Lausanne) 2023; 14:1195038. [PMID: 37635966 PMCID: PMC10456889 DOI: 10.3389/fendo.2023.1195038] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 07/24/2023] [Indexed: 08/29/2023] Open
Abstract
GABAB receptors are G-protein coupled receptors for the inhibitory neurotransmitter GABA. Functional GABAB receptors are formed as heteromers of GABAB1 and GABAB2 subunits, which further associate with various regulatory and signaling proteins to provide receptor complexes with distinct pharmacological and physiological properties. GABAB receptors are widely distributed in nervous tissue, where they are involved in a number of processes and in turn are subject to a number of regulatory mechanisms. In this review, we summarize current knowledge of the cellular distribution and function of the receptors in the inner ear and auditory pathway of the mammalian brainstem and midbrain. The findings suggest that in these regions, GABAB receptors are involved in processes essential for proper auditory function, such as cochlear amplifier modulation, regulation of spontaneous activity, binaural and temporal information processing, and predictive coding. Since impaired GABAergic inhibition has been found to be associated with various forms of hearing loss, GABAB dysfunction could also play a role in some pathologies of the auditory system.
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Affiliation(s)
- Rostislav Tureček
- Department of Auditory Neuroscience, Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Prague, Czechia
| | - Adolf Melichar
- Department of Auditory Neuroscience, Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Prague, Czechia
- Second Faculty of Medicine, Charles University, Prague, Czechia
| | - Michaela Králíková
- Department of Auditory Neuroscience, Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Prague, Czechia
| | - Bohdana Hrušková
- Department of Auditory Neuroscience, Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Prague, Czechia
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Circuits regulating pleasure and happiness - focus on potential biomarkers for circuitry including the habenuloid complex. Acta Neuropsychiatr 2022; 34:229-239. [PMID: 35587050 DOI: 10.1017/neu.2022.15] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
INTRODUCTION The multiplicity and complexity of the neuronal connections in the central nervous system make it difficult to disentangle circuits that play an essential role in the development or treatment of (neuro)psychiatric disorders. By choosing the evolutionary development of the forebrain as a starting point, a certain order in the connections can be created. The dorsal diencephalic connection (DDC) system can be applied for the development of biomarkers that can predict treatment response. MATERIALS AND METHODS After providing a brief introduction to the theory, we examined neuroanatomical publications on the connectivity of the DDC system. We then searched for neurochemical components that are specific for the habenula. RESULTS AND DISCUSSION The best strategy to find biomarkers that reflect the function of the habenular connection is to use genetic variants of receptors, transporters or enzymes specific to this complex. By activating these with probes and measuring the response in people with different functional genotypes, the usefulness of biomarkers can be assessed. CONCLUSIONS The most promising biomarkers in this respect are those linked to activation or inhibition of the nicotine receptor, dopamine D4 receptor, μ-opioid receptor and also those of the functioning of habenular glia cells (astrocytes and microglia).
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Luquin E, Paternain B, Zugasti I, Santomá C, Mengual E. Stereological estimations and neurochemical characterization of neurons expressing GABAA and GABAB receptors in the rat pedunculopontine and laterodorsal tegmental nuclei. Brain Struct Funct 2022; 227:89-110. [PMID: 34510281 PMCID: PMC8741722 DOI: 10.1007/s00429-021-02375-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 08/31/2021] [Indexed: 11/29/2022]
Abstract
To better understand GABAergic transmission at two targets of basal ganglia downstream projections, the pedunculopontine (PPN) and laterodorsal (LDT) tegmental nuclei, the anatomical localization of GABAA and GABAB receptors was investigated in both nuclei. Specifically, the total number of neurons expressing the GABAA receptor γ2 subunit (GABAAR γ2) and the GABAB receptor R2 subunit (GABAB R2) in PPN and LDT was estimated using stereological methods, and the neurochemical phenotype of cells expressing each subunit was also determined. The mean number of non-cholinergic cells expressing GABAAR γ2 was 9850 ± 1856 in the PPN and 8285 ± 962 in the LDT, whereas those expressing GABAB R2 were 7310 ± 1970 and 9170 ± 1900 in the PPN and LDT, respectively. In addition, all cholinergic neurons in both nuclei co-expressed GABAAR γ2 and 95-98% of them co-expressed GABAB R2. Triple labeling using in situ hybridization revealed that 77% of GAD67 mRNA-positive cells in the PPT and 49% in the LDT expressed GABAAR γ2, while 90% (PPN) and 65% (LDT) of Vglut2 mRNA-positive cells also expressed GABAAR γ2. In contrast, a similar proportion (~2/3) of glutamatergic and GABAergic cells co-expressed GABAB R2 in both nuclei. The heterogeneous distribution of GABAAR and GABABR among non-cholinergic cells in PPN and LDT may give rise to physiological differences within each neurochemical subpopulation. In addition, the dissimilar proportion of GABAAR γ2-expressing glutamatergic and GABAergic neurons in the PPN and LDT may contribute to some of the functional differences found between the two nuclei.
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Affiliation(s)
- Esther Luquin
- Department of Pathology, Anatomy, and Physiology, School of Medicine, University of Navarra, Ed. Los Castaños, Irunlarrea 1, 31008 Pamplona, Spain
- IdiSNA, Navarra Institute for Health Research, 31008 Pamplona, Spain
| | - Beatriz Paternain
- Department of Pathology, Anatomy, and Physiology, School of Medicine, University of Navarra, Ed. Los Castaños, Irunlarrea 1, 31008 Pamplona, Spain
- IdiSNA, Navarra Institute for Health Research, 31008 Pamplona, Spain
| | - Inés Zugasti
- Department of Pathology, Anatomy, and Physiology, School of Medicine, University of Navarra, Ed. Los Castaños, Irunlarrea 1, 31008 Pamplona, Spain
- IdiSNA, Navarra Institute for Health Research, 31008 Pamplona, Spain
| | - Carmen Santomá
- Department of Pathology, Anatomy, and Physiology, School of Medicine, University of Navarra, Ed. Los Castaños, Irunlarrea 1, 31008 Pamplona, Spain
- IdiSNA, Navarra Institute for Health Research, 31008 Pamplona, Spain
| | - Elisa Mengual
- Department of Pathology, Anatomy, and Physiology, School of Medicine, University of Navarra, Ed. Los Castaños, Irunlarrea 1, 31008 Pamplona, Spain
- IdiSNA, Navarra Institute for Health Research, 31008 Pamplona, Spain
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Abstract
A substantial fraction of the human population suffers from chronic pain states, which often cannot be sufficiently treated with existing drugs. This calls for alternative targets and strategies for the development of novel analgesics. There is substantial evidence that the G protein-coupled GABAB receptor is involved in the processing of pain signals and thus has long been considered a valuable target for the generation of analgesics to treat chronic pain. In this review, the contribution of GABAB receptors to the generation and modulation of pain signals, their involvement in chronic pain states as well as their target suitability for the development of novel analgesics is discussed.
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Affiliation(s)
- Dietmar Benke
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland.
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London E, Wester JC, Bloyd M, Bettencourt S, McBain CJ, Stratakis CA. Loss of habenular Prkar2a reduces hedonic eating and increases exercise motivation. JCI Insight 2020; 5:141670. [PMID: 33141766 PMCID: PMC7714411 DOI: 10.1172/jci.insight.141670] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 10/28/2020] [Indexed: 01/25/2023] Open
Abstract
The habenula (Hb) is a bilateral, evolutionarily conserved epithalamic structure connecting forebrain and midbrain structures that has gained attention for its roles in depression, addiction, rewards processing, and motivation. Of its 2 major subdivisions, the medial Hb (MHb) and lateral Hb (LHb), MHb circuitry and function are poorly understood relative to those of the LHb. Prkar2a codes for cAMP-dependent protein kinase (PKA) regulatory subunit IIα (RIIα), a component of the PKA holoenzyme at the center of one of the major cell-signaling pathways conserved across systems and species. Type 2 regulatory subunits (RIIα, RIIβ) determine the subcellular localization of PKA, and unlike other PKA subunits, Prkar2a has minimal brain expression except in the MHb. We previously showed that RIIα-knockout (RIIα-KO) mice resist diet-induced obesity. In the present study, we report that RIIα-KO mice have decreased consumption of palatable, “rewarding” foods and increased motivation for voluntary exercise. Prkar2a deficiency led to decreased habenular PKA enzymatic activity and impaired dendritic localization of PKA catalytic subunits in MHb neurons. Reexpression of Prkar2a in the Hb rescued this phenotype, confirming differential roles for Prkar2a in regulating the drives for palatable foods and voluntary exercise. Our findings show that in the MHb decreased PKA signaling and dendritic PKA activity decrease motivation for palatable foods, while enhancing the motivation for exercise, a desirable combination of behaviors. Decreased habenular PKA signaling and altered localization of PKA catalytic subunits in medial habenula dendrites caused by Prkar2a deletion led to increased voluntary running and decreased sucrose solution intake in mice.
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Affiliation(s)
| | - Jason C Wester
- Section on Cellular and Synaptic Physiology, Eunice Kennedy Shriver, National Institute for Child Health and Human Development, NIH, Bethesda, Maryland, USA
| | | | | | - Chris J McBain
- Section on Cellular and Synaptic Physiology, Eunice Kennedy Shriver, National Institute for Child Health and Human Development, NIH, Bethesda, Maryland, USA
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Cieślik P, Wierońska JM. Regulation of Glutamatergic Activity via Bidirectional Activation of Two Select Receptors as a Novel Approach in Antipsychotic Drug Discovery. Int J Mol Sci 2020; 21:ijms21228811. [PMID: 33233865 PMCID: PMC7699963 DOI: 10.3390/ijms21228811] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Revised: 11/10/2020] [Accepted: 11/16/2020] [Indexed: 12/14/2022] Open
Abstract
Schizophrenia is a mental disorder that affects approximately 1-2% of the population and develops in early adulthood. The disease is characterized by positive, negative, and cognitive symptoms. A large percentage of patients with schizophrenia have a treatment-resistant disease, and the risk of developing adverse effects is high. Many researchers have attempted to introduce new antipsychotic drugs to the clinic, but most of these treatments failed, and the diversity of schizophrenic symptoms is one of the causes of disappointing results. The present review summarizes the results of our latest papers, showing that the simultaneous activation of two receptors with sub-effective doses of their ligands induces similar effects as the highest dose of each compound alone. The treatments were focused on inhibiting the increased glutamate release responsible for schizophrenia arousal, without interacting with dopamine (D2) receptors. Ligands activating metabotropic receptors for glutamate, GABAB or muscarinic receptors were used, and the compounds were administered in several different combinations. Some combinations reversed all schizophrenia-related deficits in animal models, but others were active only in select models of schizophrenia symptoms (i.e., cognitive or negative symptoms).
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Mechanisms and Regulation of Neuronal GABA B Receptor-Dependent Signaling. Curr Top Behav Neurosci 2020; 52:39-79. [PMID: 32808092 DOI: 10.1007/7854_2020_129] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
γ-Aminobutyric acid B receptors (GABABRs) are broadly expressed throughout the central nervous system where they play an important role in regulating neuronal excitability and synaptic transmission. GABABRs are G protein-coupled receptors that mediate slow and sustained inhibitory actions via modulation of several downstream effector enzymes and ion channels. GABABRs are obligate heterodimers that associate with diverse arrays of proteins to form modular complexes that carry out distinct physiological functions. GABABR-dependent signaling is fine-tuned and regulated through a multitude of mechanisms that are relevant to physiological and pathophysiological states. This review summarizes the current knowledge on GABABR signal transduction and discusses key factors that influence the strength and sensitivity of GABABR-dependent signaling in neurons.
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10
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Shiotani H, Miyata M, Kameyama T, Mandai K, Yamasaki M, Watanabe M, Mizutani K, Takai Y. Nectin‐2α is localized at cholinergic neuron dendrites and regulates synapse formation in the medial habenula. J Comp Neurol 2020; 529:450-477. [DOI: 10.1002/cne.24958] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 05/08/2020] [Accepted: 05/14/2020] [Indexed: 11/09/2022]
Affiliation(s)
- Hajime Shiotani
- Division of Pathogenetic Signaling, Department of Biochemistry and Molecular Biology Kobe University Graduate School of Medicine Kobe Japan
| | - Muneaki Miyata
- Division of Pathogenetic Signaling, Department of Biochemistry and Molecular Biology Kobe University Graduate School of Medicine Kobe Japan
| | - Takeshi Kameyama
- Division of Pathogenetic Signaling, Department of Biochemistry and Molecular Biology Kobe University Graduate School of Medicine Kobe Japan
| | - Kenji Mandai
- Division of Pathogenetic Signaling, Department of Biochemistry and Molecular Biology Kobe University Graduate School of Medicine Kobe Japan
- Department of Molecular and Cellular Neurobiology Kitasato University Graduate School of Medical Sciences Sagamihara Japan
- Department of Biochemistry Kitasato University School of Medicine Sagamihara Japan
| | - Miwako Yamasaki
- Department of Anatomy, Faculty of Medicine Hokkaido University Sapporo Japan
| | - Masahiko Watanabe
- Department of Anatomy, Faculty of Medicine Hokkaido University Sapporo Japan
| | - Kiyohito Mizutani
- Division of Pathogenetic Signaling, Department of Biochemistry and Molecular Biology Kobe University Graduate School of Medicine Kobe Japan
| | - Yoshimi Takai
- Division of Pathogenetic Signaling, Department of Biochemistry and Molecular Biology Kobe University Graduate School of Medicine Kobe Japan
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11
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Roman E, Weininger J, Lim B, Roman M, Barry D, Tierney P, O'Hanlon E, Levins K, O'Keane V, Roddy D. Untangling the dorsal diencephalic conduction system: a review of structure and function of the stria medullaris, habenula and fasciculus retroflexus. Brain Struct Funct 2020; 225:1437-1458. [PMID: 32367265 DOI: 10.1007/s00429-020-02069-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2019] [Accepted: 04/11/2020] [Indexed: 12/23/2022]
Abstract
The often-overlooked dorsal diencephalic conduction system (DDCS) is a highly conserved pathway linking the basal forebrain and the monoaminergic brainstem. It consists of three key structures; the stria medullaris, the habenula and the fasciculus retroflexus. The first component of the DDCS, the stria medullaris, is a discrete bilateral tract composed of fibers from the basal forebrain that terminate in the triangular eminence of the stalk of the pineal gland, known as the habenula. The habenula acts as a relay hub where incoming signals from the stria medullaris are processed and subsequently relayed to the midbrain and hindbrain monoaminergic nuclei through the fasciculus retroflexus. As a result of its wide-ranging connections, the DDCS has recently been implicated in a wide range of behaviors related to reward processing, aversion and motivation. As such, an understanding of the structure and connections of the DDCS may help illuminate the pathophysiology of neuropsychiatric disorders such as depression, addiction and pain. This is the first review of all three components of the DDCS, the stria medullaris, the habenula and the fasciculus retroflexus, with particular focus on their anatomy, function and development.
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Affiliation(s)
- Elena Roman
- Department of Psychiatry, Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin 2, Ireland.,Department of Psychiatry, Education and Research Centre , Royal College of Surgeons in Ireland, Beaumont Hospital, Dublin 9, Ireland
| | - Joshua Weininger
- Department of Psychiatry, Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin 2, Ireland
| | - Basil Lim
- Department of Psychiatry, Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin 2, Ireland.,Department of Game Design, Technological University Dublin, Dublin 2, Ireland
| | - Marin Roman
- Department of Psychiatry, Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin 2, Ireland
| | - Denis Barry
- Anatomy Department, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland
| | - Paul Tierney
- Anatomy Department, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland
| | - Erik O'Hanlon
- Department of Psychiatry, Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin 2, Ireland.,Department of Psychiatry, Education and Research Centre , Royal College of Surgeons in Ireland, Beaumont Hospital, Dublin 9, Ireland
| | - Kirk Levins
- Department of Anaesthetics, Intensive Care and Pain Medicine, St. Vincent's University Hospital, Dublin 4, Ireland
| | - Veronica O'Keane
- Department of Psychiatry, Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin 2, Ireland
| | - Darren Roddy
- Department of Psychiatry, Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin 2, Ireland.
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12
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Cansler HL, Wright KN, Stetzik LA, Wesson DW. Neurochemical organization of the ventral striatum's olfactory tubercle. J Neurochem 2020; 152:425-448. [PMID: 31755104 PMCID: PMC7042089 DOI: 10.1111/jnc.14919] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 11/08/2019] [Accepted: 11/17/2019] [Indexed: 12/11/2022]
Abstract
The ventral striatum is a collection of brain structures, including the nucleus accumbens, ventral pallidum and the olfactory tubercle (OT). While much attention has been devoted to the nucleus accumbens, a comprehensive understanding of the ventral striatum and its contributions to neurological diseases requires an appreciation for the complex neurochemical makeup of the ventral striatum's other components. This review summarizes the rich neurochemical composition of the OT, including the neurotransmitters, neuromodulators and hormones present. We also address the receptors and transporters involved in each system as well as their putative functional roles. Finally, we end with briefly reviewing select literature regarding neurochemical changes in the OT in the context of neurological disorders, specifically neurodegenerative disorders. By overviewing the vast literature on the neurochemical composition of the OT, this review will serve to aid future research into the neurobiology of the ventral striatum.
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Affiliation(s)
- Hillary L Cansler
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, USA
- Center for Smell and Taste, University of Florida, Gainesville, FL, USA
| | - Katherine N Wright
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, USA
- Center for Smell and Taste, University of Florida, Gainesville, FL, USA
- Center for Addiction Research and Education, University of Florida, Gainesville, FL, USA
| | - Lucas A Stetzik
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, USA
- Center for Smell and Taste, University of Florida, Gainesville, FL, USA
| | - Daniel W Wesson
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, USA
- Center for Smell and Taste, University of Florida, Gainesville, FL, USA
- Center for Addiction Research and Education, University of Florida, Gainesville, FL, USA
- Norman Fixel Institute for Neurological Diseases, University of Florida, Gainesville, FL, USA
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13
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Negrete-Díaz JV, Shumilov K, Real MÁ, Medina-Luque J, Valderrama-Carvajal A, Flores G, Rodríguez-Moreno A, Rivera A. Pharmacological activation of dopamine D 4 receptor modulates morphine-induced changes in the expression of GAD 65/67 and GABA B receptors in the basal ganglia. Neuropharmacology 2019; 152:22-29. [PMID: 30682345 DOI: 10.1016/j.neuropharm.2019.01.024] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2018] [Revised: 12/19/2018] [Accepted: 01/21/2019] [Indexed: 11/27/2022]
Abstract
Dopamine D4 receptor (D4R) stimulation, in a putative D4R/μ opioid heteroreceptor (MOR) complex, counteracts the molecular, cellular and behavioural actions of morphine which are associated with morphine addiction, without any effect on its analgesic properties. In the present work, we have evaluated the role of D4R in modulating the effects of a continuous treatment with morphine on the GABAergic system in the basal ganglia. It has been demonstrated that the co-administration of a D4R agonist together with morphine leads to a restoration of GABA signaling by preventing drug-induced changes in GAD65/67 expression in the caudate putamen, globus palidus and substantia nigra. Results from GABABR1 and GABABR2 expression suggest a role of D4R in modulation of the GABAB heteroreceptor complexes along the basal ganglia, especially in the functional divisions of the caudate putamen. These results provide a new proof of the functional interaction between D4R and MOR and we postulate this putative heteroreceptor complex as a key target for the development of a new strategy to prevent the addictive effects of morphine in the treatment of pain. This article is part of the Special Issue entitled 'Receptor heteromers and their allosteric receptor-receptor interactions'.
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Affiliation(s)
- José Vicente Negrete-Díaz
- Universidad de Málaga, Instituto de Investigación Biomédica, Málaga, Spain; División de Ciencias de la Salud e Ingenierías, Campus Celaya-Salvatierra, Universidad de Guanajuato, Guanajuato, Mexico (permanent address)
| | - Kirill Shumilov
- Universidad de Málaga, Instituto de Investigación Biomédica, Málaga, Spain
| | - M Ángeles Real
- Universidad de Málaga, Instituto de Investigación Biomédica, Málaga, Spain
| | - José Medina-Luque
- Universidad de Málaga, Instituto de Investigación Biomédica, Málaga, Spain; German Center for Neurodegenerative Diseases (DZNE) Munich, German (permanent address)
| | | | - Gonzalo Flores
- Laboratorio de Neuropsiquiatría, Instituto de Fisiología, Universidad Autónoma de Puebla, Puebla, Mexico
| | | | - Alicia Rivera
- Universidad de Málaga, Instituto de Investigación Biomédica, Málaga, Spain.
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Derouiche L, Massotte D. G protein-coupled receptor heteromers are key players in substance use disorder. Neurosci Biobehav Rev 2018; 106:73-90. [PMID: 30278192 DOI: 10.1016/j.neubiorev.2018.09.026] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2018] [Revised: 09/25/2018] [Accepted: 09/26/2018] [Indexed: 12/19/2022]
Abstract
G protein-coupled receptors (GPCR) represent the largest family of membrane proteins in the human genome. Physical association between two different GPCRs is linked to functional interactions which generates a novel entity, called heteromer, with specific ligand binding and signaling properties. Heteromerization is increasingly recognized to take place in the mesocorticolimbic pathway and to contribute to various aspects related to substance use disorder. This review focuses on heteromers identified in brain areas relevant to drug addiction. We report changes at the molecular and cellular levels that establish specific functional impact and highlight behavioral outcome in preclinical models. Finally, we briefly discuss selective targeting of native heteromers as an innovative therapeutic option.
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Affiliation(s)
- Lyes Derouiche
- Institut des Neurosciences Cellulaires et Integratives, UPR 3212, 5 rue Blaise Pascal, F-67000 Strasbourg, France
| | - Dominique Massotte
- Institut des Neurosciences Cellulaires et Integratives, UPR 3212, 5 rue Blaise Pascal, F-67000 Strasbourg, France.
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15
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Salio C, Merighi A, Bardoni R. GABA B receptors-mediated tonic inhibition of glutamate release from Aβ fibers in rat laminae III/IV of the spinal cord dorsal horn. Mol Pain 2018; 13:1744806917710041. [PMID: 28565998 PMCID: PMC5456036 DOI: 10.1177/1744806917710041] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Presynaptic GABAB receptors (GABABRs) are highly expressed in dorsal root ganglion neurons and spinal cord dorsal horn. GABABRs located in superficial dorsal horn play an important antinociceptive role, by acting at both pre- and postsynaptic sites. GABABRs expressed in deep dorsal horn could be involved in the processing of touch sensation and possibly in the generation of tactile allodynia in chronic pain. The objective of this study was to characterize the morphological and functional properties of GABABRs expressed on Aβ fibers projecting to lamina III/IV and to understand their role in modulating excitatory synaptic transmission. We performed high-resolution electron microscopic analysis, showing that GABAB2 subunit is expressed on 71.9% of terminals in rat lamina III-IV. These terminals were engaged in axodendritic synapses and, for the 46%, also expressed glutamate immunoreactivity. Monosynaptic excitatory postsynaptic currents, evoked by Aβ fiber stimulation and recorded from lamina III/IV neurons in spinal cord slices, were strongly depressed by application of baclofen (0.1-2.5 µM), acting as a presynaptic modulator. Application of the GABABR antagonist CGP 55845 caused, in a subpopulation of neurons, the potentiation of the first of two excitatory postsynaptic currents recorded with the paired-pulse protocol, showing that GABABRs are endogenously activated. A decrease in the paired-pulse ratio accompanied the effect of CGP 55845, implying the involvement of presynaptic GABABRs. CGP 55845 facilitated only the first excitatory postsynaptic current also during a train of four consecutive stimuli applied to Aβ fibers. These results suggest that GABABRs tonically inhibit glutamate release from Aβ fibers at a subset of synapses in deep dorsal horn. This modulation specifically affects only the early phase of synaptic excitation in lamina III-IV neurons.
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Affiliation(s)
- Chiara Salio
- 1 Department of Veterinary Sciences, University of Turin, Grugliasco, Italy
| | - Adalberto Merighi
- 1 Department of Veterinary Sciences, University of Turin, Grugliasco, Italy
| | - Rita Bardoni
- 2 Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy
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Shiotani H, Miyata M, Itoh Y, Wang S, Kaito A, Mizoguchi A, Yamasaki M, Watanabe M, Mandai K, Mochizuki H, Takai Y. Localization of nectin-2α at the boundary between the adjacent somata of the clustered cholinergic neurons and its regulatory role in the subcellular localization of the voltage-gated A-type K+channel Kv4.2 in the medial habenula. J Comp Neurol 2018. [DOI: 10.1002/cne.24425] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Hajime Shiotani
- Division of Pathogenetic Signaling, Department of Biochemistry and Molecular Biology; Kobe University Graduate School of Medicine; Kobe Hyogo 650-0047 Japan
- Department of Neurology; Osaka University Graduate School of Medicine; Suita Osaka 565-0871 Japan
| | - Muneaki Miyata
- Division of Pathogenetic Signaling, Department of Biochemistry and Molecular Biology; Kobe University Graduate School of Medicine; Kobe Hyogo 650-0047 Japan
| | - Yu Itoh
- Division of Pathogenetic Signaling, Department of Biochemistry and Molecular Biology; Kobe University Graduate School of Medicine; Kobe Hyogo 650-0047 Japan
| | - Shujie Wang
- Department of Neural Regeneration and Cell Communication; Mie University Graduate School of Medicine; Tsu Mie 514-8507 Japan
| | - Aika Kaito
- Department of Neural Regeneration and Cell Communication; Mie University Graduate School of Medicine; Tsu Mie 514-8507 Japan
| | - Akira Mizoguchi
- Department of Neural Regeneration and Cell Communication; Mie University Graduate School of Medicine; Tsu Mie 514-8507 Japan
| | - Miwako Yamasaki
- Department of Anatomy, Faculty of Medicine; Hokkaido University; Sapporo Hokkaido 060-8638 Japan
| | - Masahiko Watanabe
- Department of Anatomy, Faculty of Medicine; Hokkaido University; Sapporo Hokkaido 060-8638 Japan
| | - Kenji Mandai
- Division of Pathogenetic Signaling, Department of Biochemistry and Molecular Biology; Kobe University Graduate School of Medicine; Kobe Hyogo 650-0047 Japan
| | - Hideki Mochizuki
- Department of Neurology; Osaka University Graduate School of Medicine; Suita Osaka 565-0871 Japan
| | - Yoshimi Takai
- Division of Pathogenetic Signaling, Department of Biochemistry and Molecular Biology; Kobe University Graduate School of Medicine; Kobe Hyogo 650-0047 Japan
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Quallo T, Alkhatib O, Gentry C, Andersson DA, Bevan S. G protein βγ subunits inhibit TRPM3 ion channels in sensory neurons. eLife 2017; 6. [PMID: 28826490 PMCID: PMC5593501 DOI: 10.7554/elife.26138] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Accepted: 07/24/2017] [Indexed: 02/07/2023] Open
Abstract
Transient receptor potential (TRP) ion channels in peripheral sensory neurons are functionally regulated by hydrolysis of the phosphoinositide PI(4,5)P2 and changes in the level of protein kinase mediated phosphorylation following activation of various G protein coupled receptors. We now show that the activity of TRPM3 expressed in mouse dorsal root ganglion (DRG) neurons is inhibited by agonists of the Gi-coupled µ opioid, GABA-B and NPY receptors. These agonist effects are mediated by direct inhibition of TRPM3 by Gβγ subunits, rather than by a canonical cAMP mediated mechanism. The activity of TRPM3 in DRG neurons is also negatively modulated by tonic, constitutive GPCR activity as TRPM3 responses can be potentiated by GPCR inverse agonists. GPCR regulation of TRPM3 is also seen in vivo where Gi/o GPCRs agonists inhibited and inverse agonists potentiated TRPM3 mediated nociceptive behavioural responses. DOI:http://dx.doi.org/10.7554/eLife.26138.001 TRPM3 belongs to a family of channel proteins that allow sodium and calcium ions to enter cells by forming pores in cell membranes. TRPM3 is found on the cell membranes of nerve cells; when ions flow into the nerves through the TRPM3 pores it triggers an electrical impulse. TRPM3 is responsible for helping us to detect heat, and mice without this protein find it difficult to sense painfully hot temperatures. Mice lacking TRPM3 also respond to other kinds of pain differently. Normally, a mouse with an injured paw becomes more sensitive to warm and hot temperatures, but this does not happen in mice that do not have TRPM3. When activated, other proteins called G-protein coupled receptors (or GPCRs for short) can make some members of this family of channel proteins more or less likely to open their pore. This in turn increases or decreases the flow of ions through the pore, respectively. Yet it was not clear if GPCRs also affect TRPM3 channels on the membranes of nerve cells. Quallo et al. have now discovered that “switching on” different GPCR proteins in sensory nerve cells from mice greatly reduces the flow of calcium ions though TRPM3 channels. The experiments made use of two pain-killing drugs, namely morphine and baclofen, and a molecule called neuropeptide Y to activate different GPCRs. GPCRs interact with a group of small proteins called G-proteins that, when activated by the receptor, split into two subunits, known as the α subunit and the βγ subunit. Once detached these subunits are free to act as messengers and interact with other proteins in the cell membrane. Quallo et al. found that TRPM3 is one of a small group of proteins that interact with the βγ subunits of the G-protein, which can explain how “switching on” GPCRs reduces the activity of TRPM3. Two independent studies by Dembla, Behrendt et al. and Badheka, Yudin et al. also report similar findings. There is currently a need to find more effective treatments for people suffering from long-term pain conditions and it has become clear that TRPM3 channels are involved in sensing both pain and temperature. These new findings show that drugs already used in the treatment of pain can dramatically change how TRPM3 works. These results might help scientists to find drugs that work in a similar way to dial down the activity of TRPM3 and to combat pain. Though first it will be important to confirm these new findings in human nerve cells. DOI:http://dx.doi.org/10.7554/eLife.26138.002
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Affiliation(s)
- Talisia Quallo
- Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
| | - Omar Alkhatib
- Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
| | - Clive Gentry
- Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
| | - David A Andersson
- Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
| | - Stuart Bevan
- Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
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18
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Sheilabi MA, Battacharyya D, Caetano L, Thom M, Reuber M, Duncan JS, Princivalle AP. Quantitative expression and localization of GABA B receptor protein subunits in hippocampi from patients with refractory temporal lobe epilepsy. Neuropharmacology 2017; 136:117-128. [PMID: 28782512 DOI: 10.1016/j.neuropharm.2017.08.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Revised: 08/01/2017] [Accepted: 08/02/2017] [Indexed: 01/03/2023]
Abstract
This study investigates GABAB protein expression and mRNA levels in three types of specimens. Two types of specimens from patients with temporal lobe epilepsy (TLE), secondary to hippocampal sclerosis, sclerotic hippocampal samples (TLE-HS), and tissue from the structurally preserved non-spiking ipsilateral superior temporal gyrus (TLE-STG) removed from the same patient during epilepsy surgery; and third specimen is hippocampal tissue from individuals with no history of epilepsy (post-mortem controls, PMC). mRNA expression of GABAB subunits was quantified in TLE-HS, TLE-STG and PMC specimens by qRT-PCR. Qualitative and quantitative Western blot (WB) and immunohistochemistry techniques were employed to quantify and localize GABAB proteins subunits. qRT-PCR data demonstrated an overall decrease of both GABAB1 isoforms in TLE-HS compared to TLE-STG. These results were mirrored by the WB findings. GABAB2 mRNA and protein were significantly reduced in TLE-HS samples compared to TLE-STG; however they appeared to be upregulated in TLE-HS compared to the PMC samples. Immunohistochemistry (IHC) showed that GABAB proteins were widely distributed in PMC and TLE-HS hippocampal sections with regional differences in the intensity of the signal. The higher expression of mature GABAB protein in TLE-HS than PMC is in agreement with previous studies. However, these findings could be due to post-mortem changes in PMC specimens. The TLE-STG samples examined here represent a better 'control' tissue compared to TLE-HS samples characterised by lower than expected GABAB expression. This interpretation provides a better explanation for previous functional studies suggesting reduced inhibition in TLE-HS tissue due to attenuated GABAB currents. This article is part of the "Special Issue Dedicated to Norman G. Bowery".
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Affiliation(s)
- Mariam A Sheilabi
- Biomolecular Sciences Research Centre, Sheffield Hallam University, Howard Street, Sheffield, S1 1WB, UK
| | - Dev Battacharyya
- Neurosurgery, Sheffield Hallamshire Hospital, Glossop Road, Sheffield, S10 2JF, UK
| | - Laura Caetano
- Biomolecular Sciences Research Centre, Sheffield Hallam University, Howard Street, Sheffield, S1 1WB, UK
| | - Maria Thom
- Department of Neuropathology, Institute of Neurology, UCL, Queen Square, London, UK
| | - Markus Reuber
- Academic Neurology Unit, University of Sheffield, Royal Hallamshire Hospital, Glossop Road, Sheffield, S10 2JF, UK
| | - John S Duncan
- Department of Clinical and Experimental Epilepsy, Institute of Neurology, UCL, Queen Square, London, UK
| | - Alessandra P Princivalle
- Biomolecular Sciences Research Centre, Sheffield Hallam University, Howard Street, Sheffield, S1 1WB, UK; Division of Neuroscience, Department of Pharmacology, Medical School, University of Birmingham, Birmingham, B15 2TT, UK.
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Cote-Vélez A, Martínez Báez A, Lezama L, Uribe RM, Joseph-Bravo P, Charli JL. A screen for modulators reveals that orexin-A rapidly stimulates thyrotropin releasing hormone expression and release in hypothalamic cell culture. Neuropeptides 2017; 62:11-20. [PMID: 28173961 DOI: 10.1016/j.npep.2017.01.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Revised: 01/25/2017] [Accepted: 01/30/2017] [Indexed: 12/21/2022]
Abstract
In the paraventricular nucleus of the mammalian hypothalamus, hypophysiotropic thyrotropin releasing hormone (TRH) neurons integrate metabolic information and control the activity of the thyroid axis. Additional populations of TRH neurons reside in various hypothalamic areas, with poorly defined connections and functions, albeit there is evidence that some may be related to energy balance. To establish extracellular modulators of TRH hypothalamic neurons activity, we performed a screen of neurotransmitters effects in hypothalamic cultures. Cell culture conditions were chosen to facilitate the full differentiation of the TRH neurons; these conditions had permitted the characterization of the effects of known modulators of hypophysiotropic TRH neurons. The major end-point of the screen was Trh mRNA levels, since they are generally rapidly (0.5-3h) modified by synaptic inputs onto TRH neurons; in some experiments, TRH cell content or release was also analyzed. Various modulators, including histamine, serotonin, β-endorphin, met-enkephalin, and melanin concentrating hormone, had no effect. Glutamate, as well as ionotropic agonists (kainate and N-Methyl-d-aspartic acid), increased Trh mRNA levels. Baclofen, a GABAB receptor agonist, and dopamine enhanced Trh mRNA levels. An endocannabinoid receptor 1 inverse agonist promoted TRH release. Somatostatin increased Trh mRNA levels and TRH cell content. Orexin-A rapidly increased Trh mRNA levels, TRH cell content and release, while orexin-B decreased Trh mRNA levels. These data reveal unaccounted regulators, which exert potent effects on hypothalamic TRH neurons in vitro.
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Affiliation(s)
- Antonieta Cote-Vélez
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Mor. 62271, Mexico
| | - Anabel Martínez Báez
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Mor. 62271, Mexico
| | - Leticia Lezama
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Mor. 62271, Mexico
| | - Rosa María Uribe
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Mor. 62271, Mexico
| | - Patricia Joseph-Bravo
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Mor. 62271, Mexico
| | - Jean-Louis Charli
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Mor. 62271, Mexico.
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20
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Romaus-Sanjurjo D, Fernández-López B, Sobrido-Cameán D, Barreiro-Iglesias A, Rodicio MC. Cloning of the GABA B Receptor Subunits B1 and B2 and their Expression in the Central Nervous System of the Adult Sea Lamprey. Front Neuroanat 2016; 10:118. [PMID: 28008311 PMCID: PMC5143684 DOI: 10.3389/fnana.2016.00118] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 11/22/2016] [Indexed: 11/25/2022] Open
Abstract
In vertebrates, γ-aminobutyric acid (GABA) is the main inhibitory transmitter in the central nervous system (CNS) acting through ionotropic (GABAA) and metabotropic (GABAB) receptors. The GABAB receptor produces a slow inhibition since it activates second messenger systems through the binding and activation of guanine nucleotide-binding proteins [G-protein-coupled receptors (GPCRs)]. Lampreys are a key reference to understand molecular evolution in vertebrates. The importance of the GABAB receptor for the modulation of the circuits controlling locomotion and other behaviors has been shown in pharmacological/physiological studies in lampreys. However, there is no data about the sequence of the GABAB subunits or their expression in the CNS of lampreys. Our aim was to identify the sea lamprey GABAB1 and GABAB2 transcripts and study their expression in the CNS of adults. We cloned two partial sequences corresponding to the GABAB1 and GABAB2 cDNAs of the sea lamprey as confirmed by sequence analysis and comparison with known GABAB sequences of other vertebrates. In phylogenetic analyses, the sea lamprey GABAB sequences clustered together with GABABs sequences of vertebrates and emerged as an outgroup to all gnathostome sequences. We observed a broad and overlapping expression of both transcripts in the entire CNS. Expression was mainly observed in neuronal somas of the periventricular regions including the identified reticulospinal cells. No expression was observed in identifiable fibers. Comparison of our results with those reported in other vertebrates indicates that a broad and overlapping expression of the GABAB subunits in the CNS is a conserved character shared by agnathans and gnathostomes.
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Affiliation(s)
- Daniel Romaus-Sanjurjo
- Department of Functional Biology, CIBUS, Faculty of Biology, Universidade de Santiago de Compostela Santiago de Compostela, Spain
| | - Blanca Fernández-López
- Department of Functional Biology, CIBUS, Faculty of Biology, Universidade de Santiago de Compostela Santiago de Compostela, Spain
| | - Daniel Sobrido-Cameán
- Department of Functional Biology, CIBUS, Faculty of Biology, Universidade de Santiago de Compostela Santiago de Compostela, Spain
| | - Antón Barreiro-Iglesias
- Department of Functional Biology, CIBUS, Faculty of Biology, Universidade de Santiago de Compostela Santiago de Compostela, Spain
| | - María Celina Rodicio
- Department of Functional Biology, CIBUS, Faculty of Biology, Universidade de Santiago de Compostela Santiago de Compostela, Spain
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Kalinichev M, Girard F, Haddouk H, Rouillier M, Riguet E, Royer-Urios I, Mutel V, Lütjens R, Poli S. The drug candidate, ADX71441, is a novel, potent and selective positive allosteric modulator of the GABA B receptor with a potential for treatment of anxiety, pain and spasticity. Neuropharmacology 2016; 114:34-47. [PMID: 27889489 DOI: 10.1016/j.neuropharm.2016.11.016] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Revised: 11/13/2016] [Accepted: 11/21/2016] [Indexed: 11/17/2022]
Abstract
Positive allosteric modulation of the GABAB receptor is a promising alternative to direct activation of the receptor as a therapeutic approach for treatment of addiction, chronic pain, anxiety, epilepsy, autism, Fragile X syndrome, and psychosis. Here we describe in vitro and in vivo characterization of a novel, potent and selective GABAB positive allosteric modulator (PAM) N-(5-(4-(4-chloro-3-fluorobenzyl)-6-methoxy-3,5-dioxo-4,5-dihydro-1,2,4-triazin-2(3H)-yl)-2-fluorophenyl)acetamide (ADX71441). In vitro, Schild plot and reversibility tests at the target confirmed PAM properties of the compound. In mice and rats ADX71441 is bioavailable after oral administration and is brain penetrant. A single dose of ADX71441 had an anxiolytic-like profile in the mouse marble burying test (minimum effective dose; MED 3 mg/kg) as well as in the elevated plus maze test in mice and rats (both MED 3 mg/kg). Also, in mice, acute administration of ADX71441 reduced visceral pain-associated behaviors in the acetic acid-induced writhing test. ADX71441 dose-dependently reduced time on rotarod in rats (MED 10 mg/kg) indicative of muscle-relaxant qualities. ADX71441 reduced locomotor activity in mice (10 mg/kg) and rats (3 mg/kg) after single dose; however, following sub-chronic administration in mice, 30 mg/kg ADX71441 was associated with normal locomotor activity. While acute administration of ADX71441 reduced body temperature in rats and mice (both MED 10 mg/kg), the effect in the former was transient, rapidly returning to normal levels despite high concentrations of the compound remaining in plasma. Thus, the GABAB PAM ADX71441 represents a valid therapeutic approach for development of novel treatment of anxiety, pain and spasticity.
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Affiliation(s)
- Mikhail Kalinichev
- Addex Therapeutics SA, Chemin des Mines 9, CH-1202, Geneva, Switzerland.
| | - Françoise Girard
- Addex Therapeutics SA, Chemin des Mines 9, CH-1202, Geneva, Switzerland
| | - Hasnaà Haddouk
- Addex Therapeutics SA, Chemin des Mines 9, CH-1202, Geneva, Switzerland
| | - Mélanie Rouillier
- Addex Therapeutics SA, Chemin des Mines 9, CH-1202, Geneva, Switzerland
| | - Eric Riguet
- Addex Therapeutics SA, Chemin des Mines 9, CH-1202, Geneva, Switzerland
| | | | - Vincent Mutel
- Addex Therapeutics SA, Chemin des Mines 9, CH-1202, Geneva, Switzerland
| | - Robert Lütjens
- Addex Therapeutics SA, Chemin des Mines 9, CH-1202, Geneva, Switzerland
| | - Sonia Poli
- Addex Therapeutics SA, Chemin des Mines 9, CH-1202, Geneva, Switzerland
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Liu Z, Wang F, Fischer G, Hogan QH, Yu H. Peripheral nerve injury induces loss of nociceptive neuron-specific Gαi-interacting protein in neuropathic pain rat. Mol Pain 2016; 12:12/0/1744806916646380. [PMID: 27145804 PMCID: PMC4956147 DOI: 10.1177/1744806916646380] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 03/16/2016] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND Gαi-interacting protein (GINIP) is expressed specifically in dorsal root ganglion (DRG) neurons and functions in modulation of peripheral gamma-aminobutyric acid B receptor (GBR). Genetic deletion of GINIP leads to impaired responsiveness to GBR agonist-mediated analgesia in rodent. It is, however, not defined whether nerve injury changes GINIP expression. RESULTS Immunolabeling with validated antibody revealed GINIP expression in ~40% of total lumbar DRG neurons in normal adult rats. GINIP immunoreactivity was detected in ~80% of IB4-positive (nonpeptidergic) and ~30% of CGRP-positive (peptidergic) neurons. GINIP immunoreactivity in the spinal cord dorsal horn was colabeled with IB4 and partially with CGRP. In addition, GINIP was expressed in DRG neurons immunopositive for GBR1, GBR2, Gαi(s), and Gαo and was also extensively colabeled with multiple nociceptive neuronal markers, including Trpv1, NaV1.7, CaV2.2α1b, CaV3.2α1b, TrkA, and Trek2. Peripheral nerve injury by L5 spinal nerve ligation significantly decreased the proportion of GINIP immunoreactivity-positive neurons from 40 ± 8.4% to 0.8 ± 0.1% (p < 0.01, mean ± SD, four weeks after spinal nerve ligation) and the total GINIP protein to 1.3% ± 0.04% of its basal level (p < 0.01, n = 6 animals in each group, two weeks after spinal nerve ligation) in the ipsilateral L5 DRGs. CONCLUSION Our results show that GINIP is predominantly expressed by small nonpeptidergic nociceptive neurons and that nerve injury triggers loss of GINIP expression. Signal transduction roles of GINIP may be diverse as it colabeled with various subgroups of nociceptive neurons. Future studies may investigate details of the signaling mechanism engaged by GINIP, as well as the pathophysiological significance of lost expression of GINIP in neuropathic pain.
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Affiliation(s)
- Zhen Liu
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, USA Department of General Surgery, West China Hospital, Sichuan University, Chengdu, Sichuan, PR China
| | - Fei Wang
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, USA Department of Physiology, Shaanxi University of Chinese Medicine, Xianyang, Shaanxi, PR China
| | - Gregory Fischer
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Quinn H Hogan
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, USA Zablocki Veterans Affairs Medical Center, Milwaukee, WI, USA
| | - Hongwei Yu
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, USA Zablocki Veterans Affairs Medical Center, Milwaukee, WI, USA
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23
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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] [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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Butt S, Ashraf F, Porter LA, Zhang H. Sodium salicylate reduces the level of GABAB receptors in the rat's inferior colliculus. Neuroscience 2015; 316:41-52. [PMID: 26705739 DOI: 10.1016/j.neuroscience.2015.12.021] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 12/08/2015] [Accepted: 12/11/2015] [Indexed: 10/22/2022]
Abstract
Previous studies have indicated that sodium salicylate (SS) can cause hearing abnormalities through affecting the central auditory system. In order to understand central effects of the drug, we examined how a single intraperitoneal injection of the drug changed the level of subunits of the type-B γ-aminobutyric acid receptor (GABAB receptor) in the rat's inferior colliculus (IC). Immunohistochemical and western blotting experiments were conducted three hours following a drug injection, as previous studies indicated that a tinnitus-like behavior could be reliably induced in rats within this time period. Results revealed that both subunits of the receptor, GABABR1 and GABABR2, reduced their level over the entire area of the IC. Such a reduction was observed in both cell body and neuropil regions. In contrast, no changes were observed in other brain structures such as the cerebellum. Thus, a coincidence existed between a structure-specific reduction in the level of GABAB receptor subunits in the IC and the presence of a tinnitus-like behavior. This coincidence likely suggests that a reduction in the level of GABAB receptor subunits was involved in the generation of a tinnitus-like behavior and/or used by the nervous system to restore normal hearing following application of SS.
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Affiliation(s)
- S Butt
- Department of Biological Sciences, University of Windsor, Windsor, ON, Canada
| | - F Ashraf
- Department of Biological Sciences, University of Windsor, Windsor, ON, Canada
| | - L A Porter
- Department of Biological Sciences, University of Windsor, Windsor, ON, Canada
| | - H Zhang
- Department of Biological Sciences, University of Windsor, Windsor, ON, Canada.
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25
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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] [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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26
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Hanack C, Moroni M, Lima WC, Wende H, Kirchner M, Adelfinger L, Schrenk-Siemens K, Tappe-Theodor A, Wetzel C, Kuich PH, Gassmann M, Roggenkamp D, Bettler B, Lewin GR, Selbach M, Siemens J. GABA blocks pathological but not acute TRPV1 pain signals. Cell 2015; 160:759-770. [PMID: 25679765 DOI: 10.1016/j.cell.2015.01.022] [Citation(s) in RCA: 112] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Revised: 11/16/2014] [Accepted: 01/06/2015] [Indexed: 01/01/2023]
Abstract
Sensitization of the capsaicin receptor TRPV1 is central to the initiation of pathological forms of pain, and multiple signaling cascades are known to enhance TRPV1 activity under inflammatory conditions. How might detrimental escalation of TRPV1 activity be counteracted? Using a genetic-proteomic approach, we identify the GABAB1 receptor subunit as bona fide inhibitor of TRPV1 sensitization in the context of diverse inflammatory settings. We find that the endogenous GABAB agonist, GABA, is released from nociceptive nerve terminals, suggesting an autocrine feedback mechanism limiting TRPV1 sensitization. The effect of GABAB on TRPV1 is independent of canonical G protein signaling and rather relies on close juxtaposition of the GABAB1 receptor subunit and TRPV1. Activating the GABAB1 receptor subunit does not attenuate normal functioning of the capsaicin receptor but exclusively reverts its sensitized state. Thus, harnessing this mechanism for anti-pain therapy may prevent adverse effects associated with currently available TRPV1 blockers.
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Affiliation(s)
- Christina Hanack
- Department of Pharmacology, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany; Max Delbrück Center for Molecular Medicine, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Mirko Moroni
- Max Delbrück Center for Molecular Medicine, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Wanessa C Lima
- Department of Pharmacology, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
| | - Hagen Wende
- Department of Pharmacology, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
| | - Marieluise Kirchner
- Max Delbrück Center for Molecular Medicine, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Lisa Adelfinger
- Department of Biomedicine, University of Basel, CH-4056 Basel, Switzerland
| | - Katrin Schrenk-Siemens
- Department of Pharmacology, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
| | - Anke Tappe-Theodor
- Department of Pharmacology, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
| | - Christiane Wetzel
- Max Delbrück Center for Molecular Medicine, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - P Henning Kuich
- Max Delbrück Center for Molecular Medicine, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Martin Gassmann
- Department of Biomedicine, University of Basel, CH-4056 Basel, Switzerland
| | - Dennis Roggenkamp
- Beiersdorf AG, Research & Development, Unnastrasse 48, 20245 Hamburg, Germany
| | - Bernhard Bettler
- Department of Biomedicine, University of Basel, CH-4056 Basel, Switzerland
| | - Gary R Lewin
- Max Delbrück Center for Molecular Medicine, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Matthias Selbach
- Max Delbrück Center for Molecular Medicine, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Jan Siemens
- Department of Pharmacology, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany.
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Corell M, Wicher G, Radomska KJ, Dağlıkoca ED, Godskesen RE, Fredriksson R, Benedikz E, Magnaghi V, Fex Svenningsen Å. GABA and its B-receptor are present at the node of Ranvier in a small population of sensory fibers, implicating a role in myelination. J Neurosci Res 2014; 93:285-95. [DOI: 10.1002/jnr.23489] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Revised: 08/28/2014] [Accepted: 09/04/2014] [Indexed: 01/28/2023]
Affiliation(s)
- Mikael Corell
- Department of Neuroscience; Uppsala University; Uppsala Sweden
| | - Grzegorz Wicher
- Department of Neuroscience; Uppsala University; Uppsala Sweden
- Department of Genetics and Pathology; Uppsala University; Uppsala Sweden
| | | | - E. Duygu Dağlıkoca
- Department of Molecular Biology and Genetics; Bogazici University; Istanbul Turkey
| | | | | | - Eirikur Benedikz
- IMM-Neurobiology Research; University of Southern Denmark; Odense Denmark
| | - Valerio Magnaghi
- Department of Pharmacological and Biomolecular Sciences; University of Milan; Milan Italy
| | - Åsa Fex Svenningsen
- Department of Neuroscience; Uppsala University; Uppsala Sweden
- IMM-Neurobiology Research; University of Southern Denmark; Odense Denmark
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28
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Gaillard S, Lo Re L, Mantilleri A, Hepp R, Urien L, Malapert P, Alonso S, Deage M, Kambrun C, Landry M, Low SA, Alloui A, Lambolez B, Scherrer G, Le Feuvre Y, Bourinet E, Moqrich A. GINIP, a Gαi-interacting protein, functions as a key modulator of peripheral GABAB receptor-mediated analgesia. Neuron 2014; 84:123-136. [PMID: 25242222 DOI: 10.1016/j.neuron.2014.08.056] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/19/2014] [Indexed: 12/15/2022]
Abstract
One feature of neuropathic pain is a reduced GABAergic inhibitory function. Nociceptors have been suggested to play a key role in this process. However, the mechanisms behind nociceptor-mediated modulation of GABA signaling remain to be elucidated. Here we describe the identification of GINIP, a Gαi-interacting protein expressed in two distinct subsets of nonpeptidergic nociceptors. GINIP null mice develop a selective and prolonged mechanical hypersensitivity in models of inflammation and neuropathy. GINIP null mice show impaired responsiveness to GABAB, but not to delta or mu opioid receptor agonist-mediated analgesia specifically in the spared nerve injury (SNI) model. Consistently, GINIP-deficient dorsal root ganglia neurons had lower baclofen-evoked inhibition of high-voltage-activated calcium channels and a defective presynaptic inhibition of lamina IIi interneurons. These results further support the role of unmyelinated C fibers in injury-induced modulation of spinal GABAergic inhibition and identify GINIP as a key modulator of peripherally evoked GABAB-receptors signaling.
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Affiliation(s)
- Stéphane Gaillard
- Aix-Marseille-Université, CNRS, Institut de Biologie du Développement de Marseille, UMR 7288, case 907, 13288 Marseille Cedex 09, France
| | - Laure Lo Re
- Aix-Marseille-Université, CNRS, Institut de Biologie du Développement de Marseille, UMR 7288, case 907, 13288 Marseille Cedex 09, France
| | - Annabelle Mantilleri
- Aix-Marseille-Université, CNRS, Institut de Biologie du Développement de Marseille, UMR 7288, case 907, 13288 Marseille Cedex 09, France
| | - Régine Hepp
- Sorbonne Universités, UPMC Univ Paris 06, UM CR 18, Neuroscience Paris Seine, 75005 Paris, France; Centre National de la Recherche Scientifique (CNRS), UMR 8246 Paris, France; Institut national de la Santé et de la Recherche Médicale (INSERM), UMR-S 1130 Paris, France
| | - Louise Urien
- Aix-Marseille-Université, CNRS, Institut de Biologie du Développement de Marseille, UMR 7288, case 907, 13288 Marseille Cedex 09, France
| | - Pascale Malapert
- Aix-Marseille-Université, CNRS, Institut de Biologie du Développement de Marseille, UMR 7288, case 907, 13288 Marseille Cedex 09, France
| | - Serge Alonso
- Aix-Marseille-Université, CNRS, Institut de Biologie du Développement de Marseille, UMR 7288, case 907, 13288 Marseille Cedex 09, France
| | - Michael Deage
- Laboratories of Excellence, Ion Channel Science and Therapeutics, Institut de Génomique Fonctionnelle, UMR 5203, CNRS, U661, INSERM, Universités Montpellier I&II, 141 Rue de la Cardonille, 34094 Montpellier Cedex 05, France
| | - Charline Kambrun
- University Bordeaux, Interdisciplinary Institute for Neuroscience, UMR 5297, 33000 Bordeaux, France; CNRS, Interdisciplinary Institute for Neuroscience, UMR 5297, 33000 Bordeaux, France
| | - Marc Landry
- University Bordeaux, Interdisciplinary Institute for Neuroscience, UMR 5297, 33000 Bordeaux, France; CNRS, Interdisciplinary Institute for Neuroscience, UMR 5297, 33000 Bordeaux, France
| | - Sarah A Low
- Department of Anesthesiology, Perioperative and Pain Medicine, Department of Molecular and Cellular Physiology, Stanford Neurosciences Institute, Stanford University, Palo Alto, CA 94304, USA
| | - Abdelkrim Alloui
- Laboratoire de Pharmacologie Médicale, Faculté de Médecine et de Pharmacie, UMR 766 INSERM, 28 place Henri-Dunant, BP 38, 63001 Clermont-Ferrand Cedex 1, France
| | - Bertrand Lambolez
- Sorbonne Universités, UPMC Univ Paris 06, UM CR 18, Neuroscience Paris Seine, 75005 Paris, France; Centre National de la Recherche Scientifique (CNRS), UMR 8246 Paris, France; Institut national de la Santé et de la Recherche Médicale (INSERM), UMR-S 1130 Paris, France
| | - Grégory Scherrer
- Department of Anesthesiology, Perioperative and Pain Medicine, Department of Molecular and Cellular Physiology, Stanford Neurosciences Institute, Stanford University, Palo Alto, CA 94304, USA
| | - Yves Le Feuvre
- University Bordeaux, Interdisciplinary Institute for Neuroscience, UMR 5297, 33000 Bordeaux, France; CNRS, Interdisciplinary Institute for Neuroscience, UMR 5297, 33000 Bordeaux, France
| | - Emmanuel Bourinet
- Laboratories of Excellence, Ion Channel Science and Therapeutics, Institut de Génomique Fonctionnelle, UMR 5203, CNRS, U661, INSERM, Universités Montpellier I&II, 141 Rue de la Cardonille, 34094 Montpellier Cedex 05, France
| | - Aziz Moqrich
- Aix-Marseille-Université, CNRS, Institut de Biologie du Développement de Marseille, UMR 7288, case 907, 13288 Marseille Cedex 09, France.
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29
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Nerve regenerative effects of GABA-B ligands in a model of neuropathic pain. BIOMED RESEARCH INTERNATIONAL 2014; 2014:368678. [PMID: 25165701 PMCID: PMC4140148 DOI: 10.1155/2014/368678] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/12/2014] [Revised: 05/13/2014] [Accepted: 06/11/2014] [Indexed: 12/13/2022]
Abstract
Neuropathic pain arises as a direct consequence of a lesion or disease affecting the peripheral somatosensory system. It may be associated with allodynia and increased pain sensitivity. Few studies correlated neuropathic pain with nerve morphology and myelin proteins expression. Our aim was to test if neuropathic pain is related to nerve degeneration, speculating whether the modulation of peripheral GABA-B receptors may promote nerve regeneration and decrease neuropathic pain. We used the partial sciatic ligation- (PSL-) induced neuropathic model. The biochemical, morphological, and behavioural outcomes of sciatic nerve were analysed following GABA-B ligands treatments. Simultaneous 7-days coadministration of baclofen (10 mg/kg) and CGP56433 (3 mg/kg) alters tactile hypersensitivity. Concomitantly, specific changes of peripheral nerve morphology, nerve structure, and myelin proteins (P0 and PMP22) expression were observed. Nerve macrophage recruitment decreased and step coordination was improved. The PSL-induced changes in nociception correlate with altered nerve morphology and myelin protein expression. Peripheral synergic effects, via GABA-B receptor activation, promote nerve regeneration and likely ameliorate neuropathic pain.
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30
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Faroni A, Castelnovo LF, Procacci P, Caffino L, Fumagalli F, Melfi S, Gambarotta G, Bettler B, Wrabetz L, Magnaghi V. Deletion of GABA-B receptor in Schwann cells regulates remak bundles and small nociceptive C-fibers. Glia 2014; 62:548-65. [PMID: 24474699 DOI: 10.1002/glia.22625] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Revised: 12/16/2013] [Accepted: 12/19/2013] [Indexed: 12/16/2023]
Abstract
The mechanisms regulating the differentiation into non-myelinating Schwann cells is not completely understood. Recent evidence indicates that GABA-B receptors may regulate myelination and nociception in the peripheral nervous system. GABA-B receptor total knock-out mice exhibit morphological and molecular changes in peripheral myelin. The number of small myelinated fibers is higher and associated with altered pain sensitivity. Herein, we analyzed whether these changes may be produced by a specific deletion of GABA-B receptors in Schwann cells. The conditional mice (P0-GABA-B1(fl/fl)) show a morphological phenotype characterized by a peculiar increase in the number of small unmyelinated fibers and Remak bundles, including nociceptive C-fibers. The P0-GABA-B1(fl/fl) mice are hyperalgesic and allodynic. In these mice, the morphological and behavioral changes are associated with a downregulation of neuregulin 1 expression in nerves. Our findings suggest that the altered pain sensitivity derives from a Schwann cell-specific loss of GABA-B receptor functions, pointing to a role for GABA-B receptors in the regulation of Schwann cell maturation towards the non-myelinating phenotype.
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Affiliation(s)
- Alessandro Faroni
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Via Balzaretti 9, 20133, Milan, Italy; Blond McIndoe Laboratories, The University of Manchester, Institute of Inflammation and Repair, M13 9PT, Manchester, United Kingdom
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31
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Thibault K, Calvino B, Rivals I, Marchand F, Dubacq S, McMahon SB, Pezet S. Molecular mechanisms underlying the enhanced analgesic effect of oxycodone compared to morphine in chemotherapy-induced neuropathic pain. PLoS One 2014; 9:e91297. [PMID: 24618941 PMCID: PMC3949760 DOI: 10.1371/journal.pone.0091297] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Accepted: 02/07/2014] [Indexed: 11/30/2022] Open
Abstract
Oxycodone is a μ-opioid receptor agonist, used for the treatment of a large variety of painful disorders. Several studies have reported that oxycodone is a more potent pain reliever than morphine, and that it improves the quality of life of patients. However, the neurobiological mechanisms underlying the therapeutic action of these two opioids are only partially understood. The aim of this study was to define the molecular changes underlying the long-lasting analgesic effects of oxycodone and morphine in an animal model of peripheral neuropathy induced by a chemotherapic agent, vincristine. Using a behavioural approach, we show that oxycodone maintains an optimal analgesic effect after chronic treatment, whereas the effect of morphine dies down. In addition, using DNA microarray technology on dorsal root ganglia, we provide evidence that the long-term analgesic effect of oxycodone is due to an up-regulation in GABAB receptor expression in sensory neurons. These receptors are transported to their central terminals within the dorsal horn, and subsequently reinforce a presynaptic inhibition, since only the long-lasting (and not acute) anti-hyperalgesic effect of oxycodone was abolished by intrathecal administration of a GABAB receptor antagonist; in contrast, the morphine effect was unaffected. Our study demonstrates that the GABAB receptor is functionally required for the alleviating effect of oxycodone in neuropathic pain condition, thus providing new insight into the molecular mechanisms underlying the sustained analgesic action of oxycodone.
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Affiliation(s)
- Karine Thibault
- Brain Plasticity Unit, ESPCI-ParisTech, Paris, France
- Centre National de la Recherche Scientifique, UMR 8249, Paris, France
- Neurorestoration Group, The Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
- * E-mail:
| | - Bernard Calvino
- Brain Plasticity Unit, ESPCI-ParisTech, Paris, France
- Centre National de la Recherche Scientifique, UMR 8249, Paris, France
| | - Isabelle Rivals
- Equipe de Statistique Appliquée, ESPCI-ParisTech, Paris, France
| | - Fabien Marchand
- Institut National de la Santé et de la Recherche Médicale, Unité 1107, NEURO-DOL, Clermont-Ferrand, France
- Clermont Université, Université d'Auvergne, Pharmacologie Fondamentale et Clinique de la Douleur, Clermont-Ferrand, France
| | - Sophie Dubacq
- Brain Plasticity Unit, ESPCI-ParisTech, Paris, France
- Centre National de la Recherche Scientifique, UMR 8249, Paris, France
| | - Stephen B. McMahon
- Neurorestoration Group, The Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
| | - Sophie Pezet
- Brain Plasticity Unit, ESPCI-ParisTech, Paris, France
- Centre National de la Recherche Scientifique, UMR 8249, Paris, France
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32
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Viswanath H, Carter AQ, Baldwin PR, Molfese DL, Salas R. The medial habenula: still neglected. Front Hum Neurosci 2014; 7:931. [PMID: 24478666 PMCID: PMC3894476 DOI: 10.3389/fnhum.2013.00931] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Accepted: 12/22/2013] [Indexed: 01/23/2023] Open
Abstract
The habenula is a small, bilateral brain structure located at the dorsal end of the diencephalon. This structure sends projections to the dopaminergic striatum and receives inputs from the limbic forebrain, making the habenula a unique modulator of cross-talk between these brain regions. Despite strong interest in the habenula during the seventies and eighties (Herkenham and Nauta, 1977; Beckstead, 1979; Beckstead et al., 1979; Herkenham and Nauta, 1979; Caldecott-Hazard et al., 1988), interest waned due to lack of a clearly identifiable functional role. Following Matsumoto and Hikosaka's seminal work on the lateral habenula as a predictor of negative reward in monkeys, the habenula has undergone a resurgence of scientific interest. Matsumoto and Hikosaka demonstrated an increase in habenular neuron firing when monkeys did not receive an expected juice reward (Matsumoto and Hikosaka, 2007). Studies have shown that increased habenular activity inactivates dopaminergic cells in the Rostromedial Tegmental Nucleus (RMTg) through GABAergic mechanisms (Jhou et al., 2009a,b). Additional studies link habenular activity to the regulation of serotonin and norepinephrine, suggesting the habenula modulates multiple brain systems (Strecker and Rosengren, 1989; Amat et al., 2001). These discoveries ushered in a series of new studies that have refocused attention on the lateral habenula and the importance of this small brain structure (Bianco and Wilson, 2009; Jhou et al., 2009a; Matsumoto and Hikosaka, 2009; Sartorius et al., 2010; Savitz et al., 2011). Recently, Geisler and Trimble reviewed this renewed interest in: The Lateral Habenula: No Longer Neglected (Geisler and Trimble, 2008). While the lateral habenula (LHb) has been extensively studied, the anatomically and histochemically distinct medial habenula (MHb) remains largely understudied. This short review argues that the MHb is functionally important and should be studied more aggressively.
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Affiliation(s)
| | | | | | | | - Ramiro Salas
- Menninger Department of Psychiatry and Behavioral Sciences, Baylor College of MedicineHouston, TX, USA
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33
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Fukuhara K, Katafuchi T, Yoshimura M. Effects of baclofen on mechanical noxious and innocuous transmission in the spinal dorsal horn of the adult rat: in vivo patch-clamp analysis. Eur J Neurosci 2013; 38:3398-407. [PMID: 23961926 DOI: 10.1111/ejn.12345] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Revised: 06/30/2013] [Accepted: 07/25/2013] [Indexed: 12/20/2022]
Abstract
The effects of a GABAB agonist, baclofen, on mechanical noxious and innocuous synaptic transmission in the substantia gelatinosa (SG) were investigated in adult rats with the in vivo patch-clamp technique. Under current-clamp conditions, perfusion with baclofen (10 μm) on the surface of the spinal cord caused hyperpolarisation of SG neurons and a decrease in the number of action potentials elicited by pinch and touch stimuli applied to the receptive field of the ipsilateral hindlimb. The suppression of action potentials was preserved under blockade of postsynaptic G-proteins, although baclofen-induced hyperpolarisation was completely blocked. These findings suggest presynaptic effects of baclofen on the induced action potentials. Under voltage-clamp conditions, application of baclofen reduced the frequency, but not the amplitude, of miniature excitatory postsynaptic currents (mEPSCs), whereas the GABAB receptor antagonist CGP55845 increased the frequency of mEPSCs without affecting the amplitude. Furthermore, application of a GABA uptake inhibitor, nipecotic acid, decreased the frequency of mEPSCs; this effect was blocked by CGP55845, but not by the GABAA antagonist bicuculline. Both the frequency and the amplitude of the pinch-evoked barrage of excitatory postsynaptic currents (EPSCs) were suppressed by baclofen in a dose-dependent manner. The frequency and amplitude of touch-evoked EPSCs was also suppressed by baclofen, but the suppression was significantly smaller than that of pinch-evoked EPSCs. We conclude that mechanical noxious transmission is presynaptically blocked through GABAB receptors in the SG, and is more effectively suppressed than innocuous transmission, which may account for a part of the mechanism of the efficient analgesic effects of baclofen.
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Affiliation(s)
- Kaori Fukuhara
- Department of Integrative Physiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, 812-8582, Japan
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Jamal L, Khan AN, Butt S, Patel CR, Zhang H. The level and distribution of the GABA(B)R1 and GABA(B)R2 receptor subunits in the rat's inferior colliculus. Front Neural Circuits 2012. [PMID: 23189044 PMCID: PMC3506002 DOI: 10.3389/fncir.2012.00092] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The type B γ-aminobutyric acid receptor (GABA(B) receptor) is an important neurotransmitter receptor in the midbrain auditory structure, the inferior colliculus (IC). A functional GABA(B) receptor is a heterodimer consisting of two subunits, GABA(B)R1 and GABA(B)R2. Western blotting and immunohistochemical experiments were conducted to examine the expression of the two subunits over the IC including its central nucleus, dorsal cortex, and external cortex (ICc, ICd, and ICx). Results revealed that the two subunits existed in both cell bodies and the neuropil throughout the IC. The two subunits had similar regional distributions over the IC. The combined level of cell body and neuropil labeling was higher in the ICd than the other two subdivisions. Labeling in the ICc and ICx was stronger in the dorsal than the ventral regions. In spite of regional differences, no defined boundaries were formed between different areas. For both subunits, the regional distribution of immunoreactivity in the neuropil was parallel to that of combined immunoreactivity in the neuropil and cell bodies. The density of labeled cell bodies tended to be higher but sizes of cell bodies tended to be smaller in the ICd than in the other subdivisions. No systematic regional changes were found in the level of cell body immunoreactivity, except that GABA(B)R2-immunoreactive cell bodies in the ICd had slightly higher optic density (OD) than in other regions. Elongated cell bodies existed throughout the IC. Many labeled cell bodies along the outline of the IC were oriented in parallel to the outline. No strong tendency of orientation was found in labeled cell bodies in ICc. Regional distributions of the subunits in ICc correlated well with inputs to this subdivision. Our finding regarding the contrast in the level of neuropil immunoreactivity among different subdivisions is consistent with the fact that the GABA(B) receptor has different pre- and postsynaptic functions in different IC regions.
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Affiliation(s)
- Lena Jamal
- Department of Biological Sciences, University of Windsor Windsor, ON, Canada
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Palomares-Castillo E, Hernández-Pérez OR, Pérez-Carrera D, Crespo-Ramírez M, Fuxe K, Pérez de la Mora M. The intercalated paracapsular islands as a module for integration of signals regulating anxiety in the amygdala. Brain Res 2012; 1476:211-34. [DOI: 10.1016/j.brainres.2012.03.047] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Revised: 03/15/2012] [Accepted: 03/19/2012] [Indexed: 11/30/2022]
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Deficits in cognition and synaptic plasticity in a mouse model of Down syndrome ameliorated by GABAB receptor antagonists. J Neurosci 2012; 32:9217-27. [PMID: 22764230 DOI: 10.1523/jneurosci.1673-12.2012] [Citation(s) in RCA: 129] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Cognitive impairment in Down syndrome (DS) is characterized by deficient learning and memory. Mouse genetic models of DS exhibit impaired cognition in hippocampally mediated behavioral tasks and reduced synaptic plasticity of hippocampal pathways. Enhanced efficiency of GABAergic neurotransmission was implicated in those changes. We have recently shown that signaling through postsynaptic GABA(B) receptors is significantly increased in the dentate gyrus of Ts65Dn mice, a genetic model of DS. Here we examined a role for GABA(B) receptors in cognitive deficits in DS by defining the effect of selective GABA(B) receptor antagonists on behavior and synaptic plasticity of adult Ts65Dn mice. Treatment with the GABA(B) receptor antagonist CGP55845 restored memory of Ts65Dn mice in the novel place recognition, novel object recognition, and contextual fear conditioning tasks, but did not affect locomotion and performance in T-maze. The treatment increased hippocampal levels of brain-derived neurotrophic factor, equally in 2N and Ts65Dn mice. In hippocampal slices, treatment with the GABA(B) receptor antagonists CGP55845 or CGP52432 enhanced long-term potentiation (LTP) in the Ts65Dn DG. The enhancement of LTP was accompanied by an increase in the NMDA receptor-mediated component of the tetanus-evoked responses. These findings are evidence for a contribution of GABA(B) receptors to changes in hippocampal-based cognition in the Ts65Dn mouse. The ability to rescue cognitive performance through treatment with selective GABA(B) receptor antagonists motivates studies to further explore the therapeutic potential of these compounds in people with DS.
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Abstract
Signal duration is important for identifying sound sources and determining signal meaning. Duration-tuned neurons (DTNs) respond preferentially to a range of stimulus durations and maximally to a best duration (BD). Duration-tuned neurons are found in the auditory midbrain of many vertebrates, although studied most extensively in bats. Studies of DTNs across vertebrates have identified cells with BDs and temporal response bandwidths that mirror the range of species-specific vocalizations. Neural tuning to stimulus duration appears to be universal among hearing vertebrates. Herein, we test the hypothesis that neural mechanisms underlying duration selectivity may be similar across vertebrates. We instantiated theoretical mechanisms of duration tuning in computational models to systematically explore the roles of excitatory and inhibitory receptor strengths, input latencies, and membrane time constant on duration tuning response profiles. We demonstrate that models of duration tuning with similar neural circuitry can be tuned with species-specific parameters to reproduce the responses of in vivo DTNs from the auditory midbrain. To relate and validate model output to in vivo responses, we collected electrophysiological data from the inferior colliculus of the awake big brown bat, Eptesicus fuscus, and present similar in vivo data from the published literature on DTNs in rats, mice, and frogs. Our results support the hypothesis that neural mechanisms of duration tuning may be shared across vertebrates despite species-specific differences in duration selectivity. Finally, we discuss how the underlying mechanisms of duration selectivity relate to other auditory feature detectors arising from the interaction of neural excitation and inhibition.
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Díaz E, Bravo D, Rojas X, Concha ML. Morphologic and immunohistochemical organization of the human habenular complex. J Comp Neurol 2012; 519:3727-47. [PMID: 21674490 DOI: 10.1002/cne.22687] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The habenular complex (HbCpx) is a phylogenetically conserved brain structure located in the epithalamus of vertebrates. Despite its fundamental role in decision-making processes and the proposed link between habenular dysfunction and neuropsychiatric conditions, little is known about the structural and functional organization of the HbCpx in humans. The goal of this study was thus to provide a first systematic morphologic and immunohistochemical analysis of the human HbCpx to begin dissecting its nuclear and subnuclear organization. Our results confirmed that the human HbCpx is subdivided into medial (MHb) and lateral (LHb) nuclei, each showing a large degree of intranuclear morphologic heterogeneity. Analysis of serially stained sections using a combination of morphologic and immunohistochemical criteria allowed the distinction of five subnuclei in both the MHb and LHb. Overall, the observed subnuclear organization of the MHb in humans resembles the organization of subnuclei in the MHb of rats. The shape, relative size, and intranuclear organization of the LHb, however, show significant differences. The contribution of the LHb to the entire HbCpx is about five times larger in humans than in rats. Noteworthy, a dorsal domain of the LHb that contains afferent myelinated fibers from the stria medullaris and shows GABA-(B) -R(1) immunoreactive cells, appears substantially enlarged in humans when compared to rats. This feature seems to account for a large part of the relative growth in size of the LHb in humans and opens the intriguing possibility of an increased influence of limbic and striatal afferents into the LHb of humans.
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Affiliation(s)
- Eugenia Díaz
- Laboratory of Experimental Ontogeny (LEO), Anatomy and Developmental Biology Program, Institute of Biomedical Sciences, University of Chile, Santiago, Chile
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Schwindinger WF, Mirshahi UL, Baylor KA, Sheridan KM, Stauffer AM, Usefof S, Stecker MM, Mirshahi T, Robishaw JD. Synergistic roles for G-protein γ3 and γ7 subtypes in seizure susceptibility as revealed in double knock-out mice. J Biol Chem 2011; 287:7121-33. [PMID: 22207761 DOI: 10.1074/jbc.m111.308395] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The functions of different G-protein αβγ subunit combinations are traditionally ascribed to their various α components. However, the discovery of similarly diverse γ subtypes raises the possibility that they may also contribute to specificity. To test this possibility, we used a gene targeting approach to determine whether the closely related γ(3) and γ(7) subunits can perform functionally interchangeable roles in mice. In contrast to single knock-out mice that show normal survival, Gng3(-/-)Gng7(-/-) double knock-out mice display a progressive seizure disorder that dramatically reduces their median life span to only 75 days. Biochemical analyses reveal that the severe phenotype is not due to redundant roles for the two γ subunits in the same signaling pathway but rather is attributed to their unique actions in different signaling pathways. The results suggest that the γ(3) subunit is a component of a G(i/o) protein that is required for γ-aminobutyric acid, type B, receptor-regulated neuronal excitability, whereas the γ(7) subunit is a component of a G(olf) protein that is responsible for A(2A) adenosine or D(1) dopamine receptor-induced neuro-protective response. The development of this mouse model offers a novel experimental framework for exploring how signaling pathways integrate to produce normal brain function and how their combined dysfunction leads to spontaneous seizures and premature death. The results underscore the critical role of the γ subunit in this process.
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Enhanced GABAergic tone in the ventral pallidum: memory of unpleasant experiences? Neuroscience 2011; 196:131-46. [DOI: 10.1016/j.neuroscience.2011.08.058] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Revised: 08/10/2011] [Accepted: 08/25/2011] [Indexed: 01/08/2023]
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Rekik L, Daguin-Nerrière V, Petit JY, Brachet P. γ-Aminobutyric acid type B receptor changes in the rat striatum and substantia nigra following intrastriatal quinolinic acid lesions. J Neurosci Res 2011; 89:524-35. [PMID: 21290407 DOI: 10.1002/jnr.22574] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2010] [Revised: 10/25/2010] [Accepted: 11/05/2010] [Indexed: 12/16/2023]
Abstract
Changes in the regional distribution of the metabotropic GABA type B receptors (GABA(B)) were investigated in a rat model of Huntington's disease. Animals received a unilateral intrastriatal injection of quinolinic acid (QA), and GABA(B) immunoreactivity was monitored 3, 11, and 21 days postinjection in the striatum and substantia nigra (SN). Two antibodies, recognizing either the GABA(B1) or the GABA(B2) receptor subtypes, were used. QA injection rapidly induced a protracted increase in GABA(B1) or GABA(B2) immunoreactivity in the lesioned striatum, despite the neuronal loss. In the SN, a continuous increase in GABA(B1) and GABA(B2) immunoreactivity was observed at all time points in the ipsilateral pars reticulata (SNr), whereas the pars compacta (SNc) was unaffected by this phenomenon. This increase was supported by a densitometric analysis. At day 21 postlesion induction, intensely labeled stellate cells and processes were found in the ipsilateral SNr, in addition to immunoreactive neurons. Double labeling of GABA(B1) and glial fibrillary acidic protein (GFAP) showed that the stellate cells were reactive astrocytes. Hence, part of the sustained increase in GABA(B) immunoreactivity that takes place in the SNr and possibly the striatum may be ascribed to reactive astrocytes. It is suggested that GABA(B) receptors are up-regulated in these reactive astrocytes and that agonists might influence the extent of this astroglial reaction.
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Affiliation(s)
- Letaïef Rekik
- Laboratory of Pharmacology, Faculty of Pharmacy, University of Monastir, Monastir, Tunisia.
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Jamal L, Zhang H, Finlayson PG, Porter LA, Zhang H. The level and distribution of the GABA(B)R2 receptor subunit in the rat's central auditory system. Neuroscience 2011; 181:243-56. [PMID: 21371537 DOI: 10.1016/j.neuroscience.2011.02.050] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Revised: 01/31/2011] [Accepted: 02/22/2011] [Indexed: 11/27/2022]
Abstract
The GABA(B) receptor is important for the function of auditory neurons. We used Western blotting and immunohistochemical methods to examine the level and localization of GABA(B)R2, a required subunit of a functional GABA(B) receptor, in the rat's central auditory system. Results revealed that this subunit was expressed throughout the auditory system with the level being high in the layers I-V of the auditory cortex, medial geniculate nucleus, dorsomedial and lateral parts of the inferior colliculus, and the molecular and fusiform cell layers of the dorsal cochlear nucleus. Labeled cell bodies were found in all the areas showing immunoreactivity. Neuropil labeling was strong in areas with high overall levels of immunoreactivity. Regional distributions of the receptor subunit revealed clear boundaries of some auditory subnuclei including the dorsal and ventral cochlear nuclei and the lateral superior olivary nucleus. Differences in immunoreactivity were found between the central nucleus and the dorsal cortex of the inferior colliculus and between the dorsal and ventral parts of the ventral nucleus of the lateral lemniscus, although no clear boundaries were observed. No differences in immunoreactivity were found between the core and the belt areas of the auditory cortex and among the subdivisions of the medial geniculate nucleus. The regional distribution of the receptor subunit in auditory structures is consistent with inputs to these structures and the cellular localization of the receptor in auditory neurons supports the contribution of the GABA(B) receptor to synaptic responses in these neurons.
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Affiliation(s)
- L Jamal
- Department of Biological Sciences, University of Windsor, Windsor, ON N9B 3P4, Canada
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Padgett CL, Slesinger PA. GABAB receptor coupling to G-proteins and ion channels. ADVANCES IN PHARMACOLOGY 2010; 58:123-47. [PMID: 20655481 DOI: 10.1016/s1054-3589(10)58006-2] [Citation(s) in RCA: 161] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
GABA(B) receptors have been found to play a key role in regulating membrane excitability and synaptic transmission in the brain. The GABA(B) receptor is a G-protein coupled receptor (GPCR) that associates with a subset of G-proteins (pertussis toxin sensitive Gi/o family), that in turn regulate specific ion channels and trigger cAMP cascades. In this review, we describe the relationships between the GABA(B) receptor, its effectors and associated proteins that mediate GABA(B) receptor function within the brain. We discuss a unique feature of the GABA(B) receptor, the requirement for heterodimerization to produce functional receptors, as well as an increasing body of evidence that suggests GABA(B) receptors comprise a macromolecular signaling heterocomplex, critical for efficient targeting and function of the receptors. Within this complex, GABA(B) receptors associate specifically with Gi/o G-proteins that regulate voltage-gated Ca(2+) (Ca(V)) channels, G-protein activated inwardly rectifying K(+) (GIRK) channels, and adenylyl cyclase. Numerous studies have revealed that lipid rafts, scaffold proteins, targeting motifs in the receptor, and regulators of G-protein signaling (RGS) proteins also contribute to the function of GABA(B) receptors and affect cellular processes such as receptor trafficking and activity-dependent desensitization. This complex regulation of GABA(B) receptors in the brain may provide opportunities for new ways to regulate GABA-dependent inhibition in normal and diseased states of the nervous system.
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Affiliation(s)
- Claire L Padgett
- Peptide Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA, USA
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Magnaghi V. GABA and neuroactive steroid interactions in glia: new roles for old players? Curr Neuropharmacol 2010; 5:47-64. [PMID: 18615153 DOI: 10.2174/157015907780077132] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2006] [Revised: 04/24/2006] [Accepted: 07/27/2006] [Indexed: 02/06/2023] Open
Abstract
In recent years it has becoming clear that glial cells of the central and peripheral nervous system play a crucial role from the earliest stages of development throughout adult life. Glial cells are important for neuronal plasticity, axonal conduction and synaptic transmission. In this respect, glial cells are able to produce, uptake and metabolize many factors that are essential for neuronal physiology, including classic neurotransmitters and neuroactive steroids. In particular, neuroactive steroids, which are mainly synthesized by glial cells, are able to modulate some neurotransmitter receptors affecting both glia and neurons. Among the signaling systems that are specialized for neuron-glial communication, we can include neurotransmitter GABA.The main focus of this review is to illustrate the cross-talk between neurons and glial cells in terms of GABA neurotransmission and actions of neuroactive steroids. To this purpose, we will review the presence of the different GABA receptors in the glial cells of the central and peripheral nervous system. Then, we will discuss their modulation by some neuroactive steroids.
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Affiliation(s)
- Valerio Magnaghi
- Department of Endocrinology and Center of Excellence on Neurodegenerative Disease, University of Milan, Italy.
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Understanding wiring and volume transmission. ACTA ACUST UNITED AC 2010; 64:137-59. [PMID: 20347870 DOI: 10.1016/j.brainresrev.2010.03.003] [Citation(s) in RCA: 189] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2009] [Revised: 03/17/2010] [Accepted: 03/17/2010] [Indexed: 11/23/2022]
Abstract
The proposal on the existence of two main modes of intercellular communication in the central nervous system (CNS) was introduced in 1986 and called wiring transmission (WT) and volume transmission (VT). The major criterion for this classification was the different characteristics of the communication channel with physical boundaries well delimited in the case of WT (axons and their synapses; gap junctions) but not in the case of VT (the extracellular fluid filled tortuous channels of the extracellular space and the cerebrospinal fluid filled ventricular space and sub-arachnoidal space). The basic dichotomic classification of intercellular communication in the brain is still considered valid, but recent evidence on the existence of unsuspected specialized structures for intercellular communication, such as microvesicles (exosomes and shedding vesicles) and tunnelling nanotubes, calls for a refinement of the original classification model. The proposed updating is based on criteria which are deduced not only from these new findings but also from concepts offered by informatics to classify the communication networks in the CNS. These criteria allowed the identification also of new sub-classes of WT and VT, namely the "tunnelling nanotube type of WT" and the "Roamer type of VT." In this novel type of VT microvesicles are safe vesicular carriers for targeted intercellular communication of proteins, mtDNA and RNA in the CNS flowing in the extracellular fluid along energy gradients to reach target cells. In the tunnelling nanotubes proteins, mtDNA and RNA can migrate as well as entire organelles such as mitochondria. Although the existence and the role of these new types of intercellular communication in the CNS are still a matter of investigation and remain to be fully demonstrated, the potential importance of these novel types of WT and VT for brain function in health and disease is discussed.
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Bowery N. Historical Perspective and Emergence of the GABAB Receptor. GABABRECEPTOR PHARMACOLOGY - A TRIBUTE TO NORMAN BOWERY 2010; 58:1-18. [DOI: 10.1016/s1054-3589(10)58001-3] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Gangadharan V, Agarwal N, Brugger S, Tegeder I, Bettler B, Kuner R, Kurejova M. Conditional gene deletion reveals functional redundancy of GABAB receptors in peripheral nociceptors in vivo. Mol Pain 2009; 5:68. [PMID: 19925671 PMCID: PMC2785766 DOI: 10.1186/1744-8069-5-68] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2009] [Accepted: 11/19/2009] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND gamma-aminobutyric acid (GABA) is an important inhibitory neurotransmitter which mainly mediates its effects on neurons via ionotropic (GABA(A)) and metabotropic (GABA(B)) receptors. GABA(B) receptors are widely expressed in the central and the peripheral nervous system. Although there is evidence for a key function of GABA(B) receptors in the modulation of pain, the relative contribution of peripherally- versus centrally-expressed GABA(B) receptors is unclear. RESULTS In order to elucidate the functional relevance of GABA(B) receptors expressed in peripheral nociceptive neurons in pain modulation we generated and analyzed conditional mouse mutants lacking functional GABA(B1) subunit specifically in nociceptors, preserving expression in the spinal cord and brain (SNS-GABA(B1)-/- mice). Lack of the GABA(B1) subunit precludes the assembly of functional GABA(B) receptor. We analyzed SNS-GABA(B1)-/- mice and their control littermates in several models of acute and neuropathic pain. Electrophysiological studies on peripheral afferents revealed higher firing frequencies in SNS-GABA(B1)-/- mice compared to corresponding control littermates. However no differences were seen in basal nociceptive sensitivity between these groups. The development of neuropathic and chronic inflammatory pain was similar across the two genotypes. The duration of nocifensive responses evoked by intraplantar formalin injection was prolonged in the SNS-GABAB(1)-/- animals as compared to their control littermates. Pharmacological experiments revealed that systemic baclofen-induced inhibition of formalin-induced nociceptive behaviors was not dependent upon GABA(B1) expression in nociceptors. CONCLUSION This study addressed contribution of GABA(B) receptors expressed on primary afferent nociceptive fibers to the modulation of pain. We observed that neither the development of acute and chronic pain nor the analgesic effects of a systematically-delivered GABA(B) agonist was significantly changed upon a specific deletion of GABA(B) receptors from peripheral nociceptive neurons in vivo. This lets us conclude that GABA(B) receptors in the peripheral nervous system play a less important role than those in the central nervous system in the regulation of pain.
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Affiliation(s)
- Vijayan Gangadharan
- Pharmacology Institute, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany.
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Abstract
The GABA(B) receptors belong to the family of class C metabotropic receptors. They are inhibitory receptors forming obligatory heterodimers. Their analgesic role in the dorsal horn of the spinal cord is well established since more than 25 years ago. However, Baclofen, the reference agonist of the GABA(B) receptor, proved to have little efficiency in clinics in neuropathic patients. It seems therefore useful to decipher GABA(B) functions in the nociceptive circuitry, and their regulation in conditions of chronic pain. In the present review, we will focus first on the distribution of the GABA(B) subtypes. Then, we will consider their pre- and post-synaptic functions in the dorsal horn of naïve rats. Finally, we will document the mechanisms that may lead to receptor impairment in neuropathic conditions.
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Affiliation(s)
- Marc Landry
- Université Bordeaux 2, INSERM U862, 146 rue Léo Saignat, 33077 Bordeaux Cedex, France.
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Qin C, Luo M. Neurochemical phenotypes of the afferent and efferent projections of the mouse medial habenula. Neuroscience 2009; 161:827-37. [PMID: 19362132 DOI: 10.1016/j.neuroscience.2009.03.085] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2009] [Revised: 03/27/2009] [Accepted: 03/28/2009] [Indexed: 10/20/2022]
Abstract
The medial habenula (MHb) is a key bridge between limbic forebrain and midbrain monoaminergic centers. Although its exact behavioral function remains enigmatic, it is implicated in regulating many behaviors such as stress responses and circadian rhythm. Fundamental information such as the neurotransmitters in the afferent and efferent projections of the MHb remains unclear. By combining retrograde tract tracing and genetic labeling of GABAergic neurons in mice, we find that the medial septum (MS) and nucleus of diagonal band (NDB) provide GABA-ergic input to the MHb. By anterograde tracing and immunostaining against a marker of glutamatergic synapses, we find that the projection from the triangular septal nucleus (TS) to the MHb has the capacity to release glutamate. This suggests that in addition to ATP, glutamate is another neurotransmitter for the TS-->MHb projection. Finally, by combining anterograde tracing and immunostaining, we find that the MHb neurons projecting to the interpeduncular nucleus (IPN) have the capacity to release glutamate. This suggests that, in addition to acetylcholine and substance P, glutamate is another neurotransmitter used by MHb projection neurons. Our findings reveal the organization of two key neurotransmitters for the MHb afferent and efferent projections, and lay framework for future functional studies of this pathway in the brain.
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Affiliation(s)
- C Qin
- Graduate Program in Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, 100730, China
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