1
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Hökfelt T, Barde S, Xu ZQD, Kuteeva E, Rüegg J, Le Maitre E, Risling M, Kehr J, Ihnatko R, Theodorsson E, Palkovits M, Deakin W, Bagdy G, Juhasz G, Prud’homme HJ, Mechawar N, Diaz-Heijtz R, Ögren SO. Neuropeptide and Small Transmitter Coexistence: Fundamental Studies and Relevance to Mental Illness. Front Neural Circuits 2018; 12:106. [PMID: 30627087 PMCID: PMC6309708 DOI: 10.3389/fncir.2018.00106] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 11/05/2018] [Indexed: 12/31/2022] Open
Abstract
Neuropeptides are auxiliary messenger molecules that always co-exist in nerve cells with one or more small molecule (classic) neurotransmitters. Neuropeptides act both as transmitters and trophic factors, and play a role particularly when the nervous system is challenged, as by injury, pain or stress. Here neuropeptides and coexistence in mammals are reviewed, but with special focus on the 29/30 amino acid galanin and its three receptors GalR1, -R2 and -R3. In particular, galanin's role as a co-transmitter in both rodent and human noradrenergic locus coeruleus (LC) neurons is addressed. Extensive experimental animal data strongly suggest a role for the galanin system in depression-like behavior. The translational potential of these results was tested by studying the galanin system in postmortem human brains, first in normal brains, and then in a comparison of five regions of brains obtained from depressed people who committed suicide, and from matched controls. The distribution of galanin and the four galanin system transcripts in the normal human brain was determined, and selective and parallel changes in levels of transcripts and DNA methylation for galanin and its three receptors were assessed in depressed patients who committed suicide: upregulation of transcripts, e.g., for galanin and GalR3 in LC, paralleled by a decrease in DNA methylation, suggesting involvement of epigenetic mechanisms. It is hypothesized that, when exposed to severe stress, the noradrenergic LC neurons fire in bursts and release galanin from their soma/dendrites. Galanin then acts on somato-dendritic, inhibitory galanin autoreceptors, opening potassium channels and inhibiting firing. The purpose of these autoreceptors is to act as a 'brake' to prevent overexcitation, a brake that is also part of resilience to stress that protects against depression. Depression then arises when the inhibition is too strong and long lasting - a maladaption, allostatic load, leading to depletion of NA levels in the forebrain. It is suggested that disinhibition by a galanin antagonist may have antidepressant activity by restoring forebrain NA levels. A role of galanin in depression is also supported by a recent candidate gene study, showing that variants in genes for galanin and its three receptors confer increased risk of depression and anxiety in people who experienced childhood adversity or recent negative life events. In summary, galanin, a neuropeptide coexisting in LC neurons, may participate in the mechanism underlying resilience against a serious and common disorder, MDD. Existing and further results may lead to an increased understanding of how this illness develops, which in turn could provide a basis for its treatment.
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Affiliation(s)
- Tomas Hökfelt
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Swapnali Barde
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Zhi-Qing David Xu
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
- Department of Neurobiology, Beijing Key Laboratory of Neural Regeneration and Repair, Beijing Laboratory of Brain Disorders (Ministry of Science and Technology), Beijing Institute for Brain Disorders, Capital Medical University, Beijing, China
| | - Eugenia Kuteeva
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Joelle Rüegg
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
- The Center for Molecular Medicine, Stockholm, Sweden
- Swedish Toxicology Sciences Research Center, Swetox, Södertälje, Sweden
| | - Erwan Le Maitre
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Mårten Risling
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Jan Kehr
- Pronexus Analytical AB, Solna, Sweden
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Robert Ihnatko
- Department of Clinical Chemistry, Linköping University, Linköping, Sweden
- Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden
| | - Elvar Theodorsson
- Department of Clinical Chemistry, Linköping University, Linköping, Sweden
- Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden
| | - Miklos Palkovits
- Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, Hungary
| | - William Deakin
- Neuroscience and Psychiatry Unit, University of Manchester, Manchester, United Kingdom
| | - Gyorgy Bagdy
- Department of Pharmacodynamics, Semmelweis University, Budapest, Hungary
- MTA-SE Neuropsychopharmacology and Neurochemistry Research Group, Hungarian Academy of Sciences, Semmelweis University, Budapest, Hungary
- NAP 2-SE New Antidepressant Target Research Group, Hungarian Brain Research Program, Semmelweis University, Budapest, Hungary
| | - Gabriella Juhasz
- Neuroscience and Psychiatry Unit, University of Manchester, Manchester, United Kingdom
- Department of Pharmacodynamics, Semmelweis University, Budapest, Hungary
- SE-NAP2 Genetic Brain Imaging Migraine Research Group, Hungarian Brain Research Program, Semmelweis University, Budapest, Hungary
| | | | - Naguib Mechawar
- Douglas Hospital Research Centre, Verdun, QC, Canada
- Department of Psychiatry, McGill University, Montreal, QC, Canada
| | | | - Sven Ove Ögren
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
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2
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Soares FRC, Silote GP, Almeida-Santos AF, Aguiar DC, Schenberg LC, Beijamini V. Galanin microinjection into the dorsal periaqueductal gray matter produces paradigm-dependent anxiolytic effects. Brain Res Bull 2016; 121:42-7. [PMID: 26751815 DOI: 10.1016/j.brainresbull.2015.12.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Revised: 12/09/2015] [Accepted: 12/28/2015] [Indexed: 01/07/2023]
Abstract
Galanin is a peptide that is present in the central nervous system in mammals, including rodents and humans. The actions of galanin are mediated by three types of metabotropic receptors: GAL1, GAL2, and GAL3. GAL1 and GAL3 increase K(+) efflux, and GAL2 increases intracellular Ca(2+) levels. The distribution of galanin and its receptors suggests its involvement in fear and/or anxiety. The periaqueductal gray matter (PAG) is a key mediator of defensive behaviors that is both targeted by galaninergic projections and supplied with GAL1 receptors and, less markedly, GAL2 receptors. We examined the effects of galanin microinjections in the dorsal PAG (dPAG) on the performance of rats in different models of anxiety. Male Wistar rats (n=7-12) were implanted with guide cannulae in the dPAG. They received microinjections of either galanin (0.3, 1.0, and 3.0 nmol) or vehicle and were tested in the Vogel conflict test (VCT), elevated plus maze (EPM), and elevated T-maze (ETM). Rats that were tested in the ETM were further evaluated for exploratory activity in the open field test (OFT). Galanin microinjections had no effects on anxiety-like behavior in the EPM or VCT or exploratory activity in the EPM or OFT. In the ETM, however, microinjections of 3 nmol galanin impaired learned anxiety (i.e., avoidance of the open arms) without changing unconditioned fear (i.e., escape from the open arms). The present data suggest that galanin transmission in the dPAG inhibits the acquisition of anxiety-like responses in the ETM.
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Affiliation(s)
- F R C Soares
- Biochemistry and Pharmacology Postgraduate Program, Health Science Center, Federal University of Espirito Santo, Vitoria, ES 29043-900, Brazil
| | - G P Silote
- Biochemistry and Pharmacology Postgraduate Program, Health Science Center, Federal University of Espirito Santo, Vitoria, ES 29043-900, Brazil
| | - A F Almeida-Santos
- Department of Pharmacology, Federal University of Minas Gerais, Belo Horizonte, MG 31270-901, Brazil
| | - D C Aguiar
- Department of Pharmacology, Federal University of Minas Gerais, Belo Horizonte, MG 31270-901, Brazil
| | - L C Schenberg
- Biochemistry and Pharmacology Postgraduate Program, Health Science Center, Federal University of Espirito Santo, Vitoria, ES 29043-900, Brazil
| | - V Beijamini
- Biochemistry and Pharmacology Postgraduate Program, Health Science Center, Federal University of Espirito Santo, Vitoria, ES 29043-900, Brazil.
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3
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Pan NC, Bai YF, Yang Y, Hökfelt T, Xu ZQD. Activation of galanin receptor 2 stimulates large conductance Ca2+-dependent K+ (BK) channels through the IP3 pathway in human embryonic kidney (HEK293) cells. Biochem Biophys Res Commun 2014; 446:316-21. [DOI: 10.1016/j.bbrc.2014.02.110] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Accepted: 02/24/2014] [Indexed: 01/01/2023]
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4
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Yoshitake S, Kuteeva E, Hökfelt T, Mennicken F, Theodorsson E, Yamaguchi M, Kehr J, Yoshitake T. Correlation between the effects of local and intracerebroventricular infusions of galanin on 5-HT release studied by microdialysis, and distribution of galanin and galanin receptors in prefrontal cortex, ventral hippocampus, amygdala, hypothalamus, and st. Synapse 2014; 68:179-93. [DOI: 10.1002/syn.21730] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Revised: 11/26/2013] [Accepted: 12/20/2013] [Indexed: 01/30/2023]
Affiliation(s)
- Shimako Yoshitake
- Department of Physiology and Pharmacology; Karolinska Institutet; 171 77 Stockholm Sweden
| | - Eugenia Kuteeva
- Department of Neuroscience; Karolinska Institutet; 171 77 Stockholm Sweden
- Atlas Antibodies AB; AlbaNova University Center; SE-106 91 Stockholm Sweden
| | - Tomas Hökfelt
- Department of Neuroscience; Karolinska Institutet; 171 77 Stockholm Sweden
| | - Françoise Mennicken
- AstraZeneca R&D Montréal; 7171 Frederick-Banting-Ville St-Laurent Quebec H4S1Z9 Canada
| | - Elvar Theodorsson
- Divison of Clinical Chemistry; Linköping University, County Council of Östergötland; 581 85 Linköping Sweden
- Department of Clinical and Experimental Medicine; Faculty of Health Sciences, Linköping University, County Council of Östergötland; 581 85 Linköping Sweden
| | - Masatoshi Yamaguchi
- Faculty of Pharmaceutical Sciences; Fukuoka University; 8-19-1 Nanakuma, Johnan-ku Fukuoka 814-0180 Japan
| | - Jan Kehr
- Department of Physiology and Pharmacology; Karolinska Institutet; 171 77 Stockholm Sweden
- Pronexus Analytical AB; Grindstuvägen 44 167 33 Bromma Sweden
| | - Takashi Yoshitake
- Department of Physiology and Pharmacology; Karolinska Institutet; 171 77 Stockholm Sweden
- Graduate School of Medical and Dental Sciences; Kagoshima University; 8-35-1 Sakuragaoka Kagoshima 890-8544 Japan
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5
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Galanin differentially regulates acetylcholine release in ventral and dorsal hippocampus: a microdialysis study in awake rat. Neuroscience 2011; 197:172-80. [DOI: 10.1016/j.neuroscience.2011.09.035] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2011] [Revised: 09/13/2011] [Accepted: 09/14/2011] [Indexed: 11/21/2022]
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6
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Le Maître TW, Xia S, Le Maitre E, Dun XP, Lu J, Theodorsson E, Ogren SO, Hökfelt T, Xu ZQD. Galanin receptor 2 overexpressing mice display an antidepressive-like phenotype: possible involvement of the subiculum. Neuroscience 2011; 190:270-88. [PMID: 21672612 DOI: 10.1016/j.neuroscience.2011.05.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2011] [Revised: 04/21/2011] [Accepted: 05/04/2011] [Indexed: 01/13/2023]
Abstract
The behavioral phenotype of a transgenic mouse overexpressing a galanin receptor 2 (GalR2)-enhanced, green fluorescent protein (EGFP)-construct under the platelet-derived growth factor-B promoter, and of controls, was assessed in various behavioral tests, such as the Porsolt forced swim test, as well as the open field, elevated plus maze and passive avoidance tests. In addition, the distribution of GalR2-EGFP expressing cell bodies and processes was studied in the brain of these mice using histochemical methods. Three age groups of the transgenic mice demonstrated decreased levels of immobility in the forced swim test, indicative of antidepressive-like behavior and/or increased stress resistance. Anxiety-like behaviors, measured in two different tests, did not differ between the GalR2-overexpressing and the wild-type mice, nor did motor activity levels, emotional learning or memory behaviors. High levels of GalR2 mRNA and protein expression were observed in the presubiculum, subiculum, cingulate cortex, retrosplenial granular and agranular cortices, subregions of prefrontal cortex, and the olfactory bulb, regions which are directly or indirectly implicated in depression-like behavior. These results may contribute to the understanding of the pathophysiology of major depressive disorder and the role of GalR2 in the regulation of mood, and suggest a potential therapeutic effect by targeting the GalR2 for treatment of depressive disorders.
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Affiliation(s)
- T Wardi Le Maître
- Department of Neuroscience, Karolinska Institutet, Retzius Väg 8, S-17177 Stockholm, Sweden.
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7
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Novel galanin receptor subtype specific ligands in feeding regulation. Neurochem Int 2011; 58:714-20. [DOI: 10.1016/j.neuint.2011.02.012] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Revised: 01/31/2011] [Accepted: 02/10/2011] [Indexed: 11/17/2022]
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8
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Hobson SA, Holmes FE, Kerr NCH, Pope RJP, Wynick D. Mice deficient for galanin receptor 2 have decreased neurite outgrowth from adult sensory neurons and impaired pain-like behaviour. J Neurochem 2006; 99:1000-10. [PMID: 17076662 PMCID: PMC2725756 DOI: 10.1111/j.1471-4159.2006.04143.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Expression of the neuropeptide galanin is markedly up-regulated within the adult dorsal root ganglia (DRG) following peripheral nerve injury. We have previously demonstrated that galanin knockout (Gal-KO) mice have a developmental loss of a subset of DRG neurons. Galanin also plays a trophic role in the adult animal, and the rate of peripheral nerve regeneration and neurite outgrowth is reduced in adult Gal-KO mice. Here we describe the characterization of mice with an absence of GalR2 gene transcription (GalR2-MUT) and demonstrate that they have a 15% decrease in the number of calcitonin gene-related peptide (CGRP) expressing neuronal profiles in the adult DRG, associated with marked deficits in neuropathic and inflammatory pain behaviours. Adult GalR2-MUT animals also have a one third reduction in neurite outgrowth from cultured DRG neurons that cannot be rescued by either galanin or a high-affinity GalR2/3 agonist. Galanin activates extracellular signal-regulated kinase (ERK) and Akt in adult wild-type (WT) mouse DRG. Intact adult DRG from GalR2-MUT animals have lower levels of pERK and higher levels of pAkt than are found in WT controls. These data suggest that a lack of GalR2 activation in Gal-KO and GalR2-MUT animals is responsible for the observed developmental deficits in the DRG, and the decrease in neurite outgrowth in the adult.
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MESH Headings
- Animals
- Behavior, Animal/physiology
- Blotting, Western
- Extracellular Signal-Regulated MAP Kinases/metabolism
- Genotype
- Immunohistochemistry
- Male
- Mice
- Mice, Knockout
- Neurites/physiology
- Neurons, Afferent/physiology
- Pain/genetics
- Pain/psychology
- Peripheral Nerve Injuries
- Phenotype
- Phosphorylation
- Proto-Oncogene Proteins c-akt/physiology
- RNA, Messenger/biosynthesis
- RNA, Messenger/genetics
- Receptor, Galanin, Type 2/genetics
- Receptor, Galanin, Type 2/physiology
- Reverse Transcriptase Polymerase Chain Reaction
- Signal Transduction/genetics
- Signal Transduction/physiology
- Transcription, Genetic
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Affiliation(s)
- Sally-Ann Hobson
- Departments of Pharmacology and Clinical Science at South Bristol, Bristol University, Bristol, UK
| | - Fiona E. Holmes
- Departments of Pharmacology and Clinical Science at South Bristol, Bristol University, Bristol, UK
| | - Niall C. H. Kerr
- Departments of Pharmacology and Clinical Science at South Bristol, Bristol University, Bristol, UK
| | - Robert J. P. Pope
- Departments of Pharmacology and Clinical Science at South Bristol, Bristol University, Bristol, UK
| | - David Wynick
- Departments of Pharmacology and Clinical Science at South Bristol, Bristol University, Bristol, UK
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9
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Hilke S, Hökfelt T, Theodorsson E. A Short Estrogen-responsive N-terminal Galanin Homologue Found in Rat Brain and Gut with Antiserum Raised Against Rat Galanin(1-16). Neurochem Res 2006; 31:177-88. [PMID: 16586031 DOI: 10.1007/s11064-005-9007-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/31/2005] [Indexed: 11/25/2022]
Abstract
Galanin-like peptide (GALP) is currently the only known galanin(1-29) homologue. However, three different galanin receptors, of which GalR3 exhibits comparatively low affinity for galanin(1-29), and molecular heterogeneity of immunoreactive galanin are arguments for presence of other endogenous galanin homologues. Since antibodies recognize three-dimensional structures of 3-5 amino acids in a peptide, we raised antibodies in rabbits against galanin(1-16) conjugated to bovine serum albumin, looking for the presence of endogenous N-terminal galanin homologues in rat tissues. The antiserum selected had 7,830 times higher avidity for galanin(1-16) compared to galanin(1-29). A single immunoreactive component with a Stokes radius of about 8 amino acids was found. Immunohistochemistry strongly suggested that this immunoreactivity is localised in the same neurons as galanin(1-29). Furthermore, its concentration was increased in response to estrogen treatment in the same brain regions as galanin(1-29), although not as rapidly. The present results indicate the presence of a novel endogenous N-terminal galanin homologue.
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Affiliation(s)
- Susanne Hilke
- Department of Biomedicine and Surgery, Division of Clinical Chemistry, Faculty of Health Sciences, University Hospital, SE-581 82 Linköping, Sweden.
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10
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Lang R, Berger A, Santic R, Geisberger R, Hermann A, Herzog H, Kofler B. Pharmacological and functional characterization of galanin-like peptide fragments as potent galanin receptor agonists. Neuropeptides 2005; 39:179-84. [PMID: 15944009 DOI: 10.1016/j.npep.2004.12.015] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2004] [Accepted: 12/08/2004] [Indexed: 10/25/2022]
Abstract
The hypothalamic galanin-like peptide (GALP) was isolated by its ability to activate galanin receptors. The mature porcine GALP is a 60-amino acid neuropeptide proteolytically processed from a 120-amino acid precursor protein. It contains a region identical to the N-terminal 13-amino acids of the neuropeptide galanin. Within the sequence of human GALP (1-60) a potential proteolytic cleavage site between two basic amino acids is present at position 33, which might lead to a shorter C-terminally amidated peptide. In addition, the first two amino acids could be potentially removed via the action of dipeptidase IV. Ligand binding assays using the human neuroblastoma cell line SH-SY5Y transfected with the respective galanin receptors revealed that human GALP (1-60) displayed the highest affinity for the galanin receptor subtype GalR3 (IC50 = 10 nM) followed by GalR2 (IC50 = 28 nM) and GalR1 (IC50 = 77 nM). Ligand binding assays and functional studies showed that the human GALP (3-32) fragment was at least as potent as full length GALP (1-60). Other studies have shown that shorter fragments like human GALP (1-21) and GALP (22-60) were not effective on feeding responses in mice as compared to the full length peptide. Taken together these data suggest that the putative fragment GALP (3-32) might represent the strongest mediator of biological GALP activity. Furthermore it might be a useful tool to study the affinity of GALP to galanin receptors and to search for specific GALP receptors.
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Affiliation(s)
- Roland Lang
- Department of Pediatrics, Paracelsus Private Medical University Salzburg, Muellner-Hauptstrasse 48, 5020 Salzburg, Austria
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11
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Mennicken F, Hoffert C, Pelletier M, Ahmad S, O'Donnell D. Restricted distribution of galanin receptor 3 (GalR3) mRNA in the adult rat central nervous system. J Chem Neuroanat 2002; 24:257-68. [PMID: 12406501 DOI: 10.1016/s0891-0618(02)00068-6] [Citation(s) in RCA: 168] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Recent molecular cloning studies have established the existence of a third rat galanin receptor subtype, GalR3, however its precise distribution in the mammalian central nervous system (CNS) is not well established. In the present study, we examined the regional and cellular distribution of GalR3 mRNA in the CNS of the rat by in situ hybridization. Our findings indicate that GALR3 mRNA expression in the rat brain is discrete and highly restricted, concentrated mainly in the preoptic/hypothalamic area. Within the hypothalamus, GalR3 expression was confined to the paraventricular, ventromedial and dorsomedial hypothalamic nuclei. In addition to these hypothalamic nuclei, GalR3 mRNA-expressing cells were observed in the medial septum/diagonal band of Broca complex, the bed nucleus of the stria terminalis, the medial amygdaloid nucleus, the periaqueductal gray, the lateral parabrachial nucleus, the dorsal raphe nucleus, the locus coeruleus, the medial medullary reticular formation and in one of the circumventricular organs, the subfornical organ. In the spinal cord, a faint but specific ISH signal was observed over the laminae I-II with a few moderately labeled cells distributed in laminae V and X. The neuroanatomical distribution of GalR3 suggests it might be involved in mediating documented effects of galanin on food intake, fluid homeostasis, cardiovascular function and nociception.
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Affiliation(s)
- Françoise Mennicken
- AstraZeneca R&D Montreal, 7171 Frederick-Banting, St. Laurent, Quebec, Canada H4S 1Z9.
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12
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Chapter IV Localization of galanin receptor subtypes in the rat CNS. ACTA ACUST UNITED AC 2002. [DOI: 10.1016/s0924-8196(02)80006-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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13
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Liu HX, Brumovsky P, Schmidt R, Brown W, Payza K, Hodzic L, Pou C, Godbout C, Hökfelt T. Receptor subtype-specific pronociceptive and analgesic actions of galanin in the spinal cord: selective actions via GalR1 and GalR2 receptors. Proc Natl Acad Sci U S A 2001; 98:9960-4. [PMID: 11481429 PMCID: PMC55560 DOI: 10.1073/pnas.161293598] [Citation(s) in RCA: 189] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/11/2001] [Indexed: 11/18/2022] Open
Abstract
Galanin is a 29-aa neuropeptide with a complex role in pain processing. Several galanin receptor subtypes are present in dorsal root ganglia and spinal cord with a differential distribution. Here, we describe a generation of a specific galanin R2 (GalR2) agonist, AR-M1896, and its application in studies of a rat neuropathic pain model (Bennett). The results show that in normal rats mechanical and cold allodynia of the hindpaw are induced after intrathecal infusion of low-dose galanin (25 ng per 0.5 microl/h). The same effect is seen with equimolar doses of AR-M1896 or AR-M961, an agonist both at GalR1 and GalR2 receptors. In allodynic Bennett model rats, the mechanical threshold increased dose-dependently after intrathecal injection of a high dose of AR-M961, whereas no effect was observed in the control or AR-M1896 group. No effect of either of the two compounds was observed in nonallodynic Bennett model rats. These data indicate that a low dose of galanin has a nociceptive role at the spinal cord level mediated by GalR2 receptors, whereas the antiallodynic effect of high-dose galanin on neuropathic pain is mediated by the GalR1 receptors. Thus, a selective GalR1 agonist may be used to treat neuropathic pain.
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MESH Headings
- Analgesics, Non-Narcotic/administration & dosage
- Analgesics, Non-Narcotic/pharmacology
- Analgesics, Non-Narcotic/therapeutic use
- Animals
- Causalgia/chemically induced
- Causalgia/drug therapy
- Causalgia/physiopathology
- Cold Temperature/adverse effects
- Dose-Response Relationship, Drug
- Galanin/administration & dosage
- Galanin/chemistry
- Galanin/pharmacology
- Galanin/physiology
- Galanin/therapeutic use
- Galanin/toxicity
- Ganglia, Spinal/chemistry
- Ganglia, Spinal/drug effects
- Hindlimb/innervation
- Hyperesthesia/chemically induced
- Hyperesthesia/drug therapy
- Hyperesthesia/etiology
- Hyperesthesia/physiopathology
- Infusion Pumps, Implantable
- Male
- Models, Animal
- Nerve Tissue Proteins/agonists
- Nerve Tissue Proteins/physiology
- Pain Threshold/drug effects
- Peptide Fragments/chemistry
- Peptide Fragments/pharmacology
- Protein Isoforms/agonists
- Protein Isoforms/physiology
- Rats
- Rats, Sprague-Dawley
- Receptors, Galanin
- Receptors, Neuropeptide/agonists
- Receptors, Neuropeptide/physiology
- Sciatic Nerve/injuries
- Sciatica/drug therapy
- Sciatica/etiology
- Sciatica/physiopathology
- Spinal Cord/chemistry
- Spinal Cord/physiopathology
- Stress, Mechanical
- Substrate Specificity
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Affiliation(s)
- H X Liu
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
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14
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Lang R, Berger A, Hermann A, Kofler B. Biphasic response to human galanin of extracellular acidification in human Bowes melanoma cells. Eur J Pharmacol 2001; 423:135-41. [PMID: 11448477 DOI: 10.1016/s0014-2999(01)01135-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The metabolic response of galanin GAL1 receptor subtype, endogenously expressed in human Bowes melanoma (HBM) cells, was investigated. Cytosensor microphysiometry was used to determine the extracellular acidification rate. A biphasic response, consisting of a rapid increase in the extracellular acidification rate followed by a decrease below the basal level, was observed after perfusion with human galanin. The magnitude and the rate of onset of both phases were dependent on the galanin concentration. The increase in the extracellular acidification rate (maximum of 25% of basal level; -log(EC(50))=7.23+/-0.14) was transient, whereas the following decrease (maximum of 40% of basal level; -log(EC(50))=7.77+/-0.23) was sustained. The EC(50) values for the increase and decrease were in a similar range. After consecutive galanin administration, the magnitude of the response was the same as for the unexposed cells, indicating the absence of galanin receptor desensitization or internalization in HBM cells. Responses were blocked by pretreatment with pertussis toxin and phorbol-12-myristate-13-acetate (PMA), indicating a G-protein/protein kinase C signalling pathway. Our microphysiometry results show a biphasic response of the extracellular acidification rate mediated by the galanin receptor expressed in HBM cells which has not been described previously for any other endogenously expressed neuropeptide receptor.
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Affiliation(s)
- R Lang
- Department of Molecular Neurobiology and Cellular Physiology, Institute of Zoology, University of Salzburg, Hellbrunnerstrasse 34, A-5020 Salzburg, Austria
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Pérez SE, Wynick D, Steiner RA, Mufson EJ. Distribution of galaninergic immunoreactivity in the brain of the mouse. J Comp Neurol 2001; 434:158-85. [PMID: 11331523 DOI: 10.1002/cne.1171] [Citation(s) in RCA: 120] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The distribution of galaninergic immunoreactive (-ir) profiles was studied in the brain of colchicine-pretreated and non-pretreated mice. Galanin (GAL)-ir neurons and fibers were observed throughout all encephalic vesicles. Telencephalic GAL-ir neurons were found in the olfactory bulb, cerebral cortex, lateral and medial septum, diagonal band of Broca, nucleus basalis of Meynert, bed nucleus of stria terminalis, amygdala, and hippocampus. The thalamus displayed GAL-ir neurons within the anterodorsal, paraventricular, central lateral, paracentral, and central medial nuclei. GAL-ir neurons were found in several regions of the hypothalamus. In the midbrain, GAL-ir neurons appeared in the pretectal olivary nucleus, oculomotor nucleus, the medial and lateral lemniscus, periaqueductal gray, and the interpeduncular nucleus. The pons contained GAL-ir neurons within the dorsal subcoeruleus, locus coeruleus, and dorsal raphe. In the medulla oblongata, GAL-ir neurons appear in the anterodorsal and dorsal cochlear nuclei, salivatory nucleus, A5 noradrenergic cells, gigantocellular nucleus, inferior olive, solitary tract nucleus, dorsal vagal motor and hypoglossal nuclei. Only GAL-ir fibers were seen in the lateral habenula nucleus, substantia nigra, parabrachial complex, cerebellum, spinal trigeminal tract, as well as the motor root of the trigeminal and facial nerves. GAL-ir was also observed in several circumventricular organs. The widespread distribution of galanin in the mouse brain suggests that this neuropeptide plays a role in the regulation of cognitive and homeostatic functions.
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Affiliation(s)
- S E Pérez
- Department of Neurological Sciences, Rush-Presbyterian-St. Luke's Medical Center, Chicago, Illinois 60612, USA
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Reeve AJ, Walker K, Urban L, Fox A. Excitatory effects of galanin in the spinal cord of intact, anaesthetized rats. Neurosci Lett 2000; 295:25-8. [PMID: 11078928 DOI: 10.1016/s0304-3940(00)01576-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The effects of intrathecal galanin on the activity of single wide dynamic range (WDR) spinal dorsal horn neurones were analyzed in anaesthetized adult rats. Abeta-, Adelta- and C-fibres were activated by transcutaneous electrical stimulation which also induced wind-up and post-discharge. Galanin dose-dependently (0. 15-15 nmol/50 microl) enhanced Adelta-and C-fibre evoked responses, post-discharge and wind-up. Application of (D-Thr(6), D-Trp(8, 9), 15-ol)-galanin (1-15), a putative antagonist, did not attenuate the enhanced effects evoked by galanin. (D-Thr(6), D-Trp(8, 9), 15-ol)-galanin (1-15) applied alone (0.3-30 nmol/50 microl) to a separate population of neurones inhibited Abeta responses but enhanced post-discharge and wind-up in a similar pattern to galanin. Thus, (D-Thr(6), D-Trp(8, 9), 15-ol)-galanin (1-15) behaved as an agonist in the present experiments. In conclusion, in the spinal cord of the anaesthetized rat, galanin has a purely pro-nociceptive role, since it enhanced responses evoked by high-threshold fibre stimulation, along with post-discharge and wind-up of WDR neurones.
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Affiliation(s)
- A J Reeve
- Novartis Institute for Medical Sciences, 5 Gower Place, WC1E 6BN, London, UK.
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Sweerts BW, Jarrott B, Lawrence AJ. Acute and chronic restraint stress: effects on [125I]-galanin binding in normotensive and hypertensive rat brain. Brain Res 2000; 873:318-29. [PMID: 10930562 DOI: 10.1016/s0006-8993(00)02558-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The neuropeptide galanin (GAL) has been implicated in the neural response to a number of stressors including restraint; however, the effect of restraint stress on GAL receptor density in the central nervous system (CNS) has not been investigated. Normotensive (Wistar-Kyoto; WKY) and hypertensive (spontaneously hypertensive; SHR) rats were subjected to a daily 60-min restraint stress paradigm for 0 (control), 1, 3, 5 or 10 consecutive days, and the density of [125I]-GAL binding sites following exposure to restraint was compared between strains using quantitative autoradiography. Significant differences in basal (no stress) levels of GAL receptor density between WKY and SHR were detected in regions such as the central nucleus of the amygdala (Ce) and ventromedial hypothalamus (VMH) (P<0.05). In WKY, restraint stress (1 day) induced significant decreases in GAL receptor density in forebrain regions such as the Ce (-41%) and medial nucleus of the amygdala (-41%) (P<0.05). Chronic restraint (10 days) did not induce significant decreases in these nuclei in WKY, indicating that forebrain neurons containing GAL receptors in WKY possessed a functional ability to adapt to repeated restraint. In addition, restraint stress induced significant decreases in GAL receptor density in SHR in regions such as the lateral parabrachial nucleus (-43%; 5 days of restraint) and hypoglossal nucleus ( approximately -18% for entire restraint period) (P<0.05). In conclusion, restraint stress resulted in region- and strain-specific alterations in GAL receptor density, some of which may contribute to the altered stress response previously observed in hypertensive rats. The results clearly support the hypothesis that neuropeptides such as GAL are an integral component of the neural response to psychological stress, although the functional significance of the changes in GAL receptor density described in this study awaits elucidation.
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Affiliation(s)
- B W Sweerts
- Department of Pharmacology, Monash University, Wellington Road, Victoria 3800, Clayton, Australia
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Schött PA, Hökfelt T, Ogren SO. Galanin and spatial learning in the rat. Evidence for a differential role for galanin in subregions of the hippocampal formation. Neuropharmacology 2000; 39:1386-403. [PMID: 10818255 DOI: 10.1016/s0028-3908(00)00053-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Anatomical, neurochemical and behavioural evidence support a role for galanin in hippocampally mediated functions such as spatial learning and memory. To obtain more precise information on this role, galanin (3 nmol/rat) was infused via bilateral chronic cannulae into different areas of the hippocampal formation which are characterized by different galanin receptor subtypes and also by different galanin innervation patterns. The effects of infused galanin on spatial learning were examined in the Morris swim maze. Infusions of galanin into both the dorsal and ventral dentate gyrus, which mainly contain GAL-R2 receptor mRNA and a high degree of galanin-noradrenaline coexistence, significantly retarded spatial acquisition without affecting swim speed or performance in the visible platform test. This spatial learning deficit was fully blocked by pretreatment with the non-selective galanin antagonist M35. Analysis of retention performance suggested that the major effect of intrahippocampal galanin is mediated via a specific disruption of acquisition mechanisms of importance for performance in the probe trial. Galanin infused into the ventral CA1 (a mainly GAL-R1 receptor mRNA expressing region) or into anterior, ventral CA3 regions did not produce any deficits in spatial learning compared to control animals. These results suggest that galanin mediates its action on spatial learning mainly through the GAL-R2 receptor subtype in areas where most of the galanin is present in noradrenergic terminals. A possible role for the GAL-R1 receptor subtype in cognition in the dorsal and ventral hippocampus remains to be defined. The results suggest a differential functional role for galanin and galanin receptor subtypes within subregions of the hippocampal formation.
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Affiliation(s)
- P A Schött
- Department of Neuroscience, Karolinska Institutet, SE-171 77, Stockholm, Sweden
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