1
|
Petrucci AN, Jones AR, Kreitlow BL, Buchanan GF. Peri-ictal activation of dorsomedial dorsal raphe serotonin neurons reduces mortality associated with maximal electroshock seizures. Brain Commun 2024; 6:fcae052. [PMID: 38487550 PMCID: PMC10939444 DOI: 10.1093/braincomms/fcae052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 12/13/2023] [Accepted: 03/08/2024] [Indexed: 03/17/2024] Open
Abstract
Over one-third of patients with epilepsy will develop refractory epilepsy and continue to experience seizures despite medical treatment. These patients are at the greatest risk for sudden unexpected death in epilepsy. The precise mechanisms underlying sudden unexpected death in epilepsy are unknown, but cardiorespiratory dysfunction and arousal impairment have been implicated. Substantial circumstantial evidence suggests serotonin is relevant to sudden unexpected death in epilepsy as it modulates sleep/wake regulation, breathing and arousal. The dorsal raphe nucleus is a major serotonergic center and a component of the ascending arousal system. Seizures disrupt the firing of dorsal raphe neurons, which may contribute to reduced responsiveness. However, the relevance of the dorsal raphe nucleus and its subnuclei to sudden unexpected death in epilepsy remains unclear. The dorsomedial dorsal raphe may be a salient target due to its role in stress and its connections with structures implicated in sudden unexpected death in epilepsy. We hypothesized that optogenetic activation of dorsomedial dorsal raphe serotonin neurons in TPH2-ChR2-YFP (n = 26) mice and wild-type (n = 27) littermates before induction of a maximal electroshock seizure would reduce mortality. In this study, pre-seizure activation of dorsal raphe nucleus serotonin neurons reduced mortality in TPH2-ChR2-YFP mice with implants aimed at the dorsomedial dorsal raphe. These results implicate the dorsomedial dorsal raphe in this novel circuit influencing seizure-induced mortality. It is our hope that these results and future experiments will define circuit mechanisms that could ultimately reduce sudden unexpected death in epilepsy.
Collapse
Affiliation(s)
- Alexandra N Petrucci
- Interdisciplinary Graduate Program in Neuroscience, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
- Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Allysa R Jones
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
- Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Benjamin L Kreitlow
- Interdisciplinary Graduate Program in Neuroscience, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
- Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Gordon F Buchanan
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
- Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| |
Collapse
|
2
|
Mohd Zahir I, Ogawa S, Dominic NA, Soga T, Parhar IS. Spexin and Galanin in Metabolic Functions and Social Behaviors With a Focus on Non-Mammalian Vertebrates. Front Endocrinol (Lausanne) 2022; 13:882772. [PMID: 35692389 PMCID: PMC9174643 DOI: 10.3389/fendo.2022.882772] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Accepted: 04/19/2022] [Indexed: 01/31/2023] Open
Abstract
Spexin (SPX) and galanin (GAL) are two neuropeptides that are phylogenetically related and have descended from a common ancestral gene. Considerable attention has been given to these two multifunctional neuropeptides because they share GAL receptors 1,2, and 3. Since GAL and SPX-synthesizing neurons have been detected in several brain areas, therefore, it can be speculated that SPX and GAL are involved in various neurophysiological functions. Several studies have shown the functions of these two neuropeptides in energy regulation, reproduction, and response to stress. SPX acts as a satiety factor to suppress food intake, while GAL has the opposite effect as an orexigenic factor. There is evidence that SPX acts as an inhibitor of reproductive functions by suppressing gonadotropin release, while GAL modulates the activity of gonadotropin-releasing hormone (GnRH) neurons in the brain and gonadotropic cells in the pituitary. SPX and GAL are responsive to stress. Furthermore, SPX can act as an anxiolytic factor, while GAL exerts anti-depressant and pro-depressive effects depending on the receptor it binds. This review describes evidence supporting the central roles of SPX and GAL neuropeptides in energy balance, reproduction, stress, and social behaviors, with a particular focus on non-mammalian vertebrate systems.
Collapse
Affiliation(s)
- Izzati Mohd Zahir
- Brain Research Institute Monash Sunway, School of Medicine and Health Sciences, Monash University Malaysia, Subang Jaya, Malaysia
| | - Satoshi Ogawa
- Brain Research Institute Monash Sunway, School of Medicine and Health Sciences, Monash University Malaysia, Subang Jaya, Malaysia
| | | | - Tomoko Soga
- Brain Research Institute Monash Sunway, School of Medicine and Health Sciences, Monash University Malaysia, Subang Jaya, Malaysia
| | - Ishwar S. Parhar
- Brain Research Institute Monash Sunway, School of Medicine and Health Sciences, Monash University Malaysia, Subang Jaya, Malaysia
- *Correspondence: Ishwar S. Parhar,
| |
Collapse
|
3
|
Involvement of Scratch2 in GalR1-mediated depression-like behaviors in the rat ventral periaqueductal gray. Proc Natl Acad Sci U S A 2021; 118:1922586118. [PMID: 34108238 DOI: 10.1073/pnas.1922586118] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Galanin receptor1 (GalR1) transcript levels are elevated in the rat ventral periaqueductal gray (vPAG) after chronic mild stress (CMS) and are related to depression-like behavior. To explore the mechanisms underlying the elevated GalR1 expression, we carried out molecular biological experiments in vitro and in animal behavioral experiments in vivo. It was found that a restricted upstream region of the GalR1 gene, from -250 to -220, harbors an E-box and plays a negative role in the GalR1 promoter activity. The transcription factor Scratch2 bound to the E-box to down-regulate GalR1 promoter activity and lower expression levels of the GalR1 gene. The expression of Scratch2 was significantly decreased in the vPAG of CMS rats. Importantly, local knockdown of Scratch2 in the vPAG caused elevated expression of GalR1 in the same region, as well as depression-like behaviors. RNAscope analysis revealed that GalR1 mRNA is expressed together with Scratch2 in both GABA and glutamate neurons. Taking these data together, our study further supports the involvement of GalR1 in mood control and suggests a role for Scratch2 as a regulator of depression-like behavior by repressing the GalR1 gene in the vPAG.
Collapse
|
4
|
Gartside SE, Yurttaser AE, Burns AL, Jovanović N, Smith KJ, Amegashiti NS, Olthof BMJ. A role for nitric oxide in serotonin neurons of the midbrain raphe nuclei. Eur J Neurosci 2020; 51:1881-1899. [DOI: 10.1111/ejn.14713] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 02/03/2020] [Accepted: 02/25/2020] [Indexed: 01/24/2023]
Affiliation(s)
- Sarah E. Gartside
- Institute of Neuroscience Newcastle University Newcastle upon Tyne UK
| | | | - Amy L. Burns
- Institute of Neuroscience Newcastle University Newcastle upon Tyne UK
| | - Nebojša Jovanović
- Institute of Neuroscience Newcastle University Newcastle upon Tyne UK
| | - Katie J. Smith
- Institute of Neuroscience Newcastle University Newcastle upon Tyne UK
| | | | - Bas M. J. Olthof
- Institute of Neuroscience Newcastle University Newcastle upon Tyne UK
| |
Collapse
|
5
|
Belmer A, Beecher K, Jacques A, Patkar OL, Sicherre F, Bartlett SE. Axonal Non-segregation of the Vesicular Glutamate Transporter VGLUT3 Within Serotonergic Projections in the Mouse Forebrain. Front Cell Neurosci 2019; 13:193. [PMID: 31133811 PMCID: PMC6523995 DOI: 10.3389/fncel.2019.00193] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 04/17/2019] [Indexed: 11/13/2022] Open
Abstract
A subpopulation of raphe 5-HT neurons expresses the vesicular glutamate transporter VGLUT3 with the co-release of glutamate and serotonin proposed to play a pivotal role in encoding reward- and anxiety-related behaviors. Serotonin axons are identifiable by immunolabeling of either serotonin (5-HT) or the plasma membrane 5-HT transporter (SERT), with SERT labeling demonstrated to be only partially overlapping with 5-HT staining. Studies investigating the colocalization or segregation of VGLUT3 within SERT or 5-HT immunolabeled boutons have led to inconsistent results. Therefore, we combined immunohistochemistry, high resolution confocal imaging, and 3D-reconstruction techniques to map and quantify the distribution of VGLUT3 immunoreactive boutons within 5-HT vs. SERT-positive axons in various regions of the mouse forebrain, including the prefrontal cortex, nucleus accumbens core and shell, bed nucleus of the stria terminalis, dorsal striatum, lateral septum, basolateral and central amygdala, and hippocampus. Our results demonstrate that about 90% of 5-HT boutons are colocalized with SERT in almost all the brain regions studied, which therefore reveals that VGLUT3 and SERT do not segregate. However, in the posterior part of the NAC shell, we confirmed the presence of a subtype of 5-HT immunoreactive axons that lack the SERT. Interestingly, about 90% of the 5-HT/VGLUT3 boutons were labeled for the SERT in this region, suggesting that VGLUT3 is preferentially located in SERT immunoreactive 5-HT boutons. This work demonstrates that VGLUT3 and SERT cannot be used as specific markers to classify the different subtypes of 5-HT axons.
Collapse
Affiliation(s)
- Arnauld Belmer
- Translational Research Institute, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia
| | - Kate Beecher
- Translational Research Institute, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia
| | - Angela Jacques
- Translational Research Institute, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia
| | - Omkar L Patkar
- QIMR Berghofer Medical Research Institute, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia
| | - Florian Sicherre
- Biologie Integrative et Physiologie, Université Pierre et Marie Curie, Paris, France
| | - Selena E Bartlett
- Translational Research Institute, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia
| |
Collapse
|
6
|
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.
Collapse
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
| |
Collapse
|
7
|
Wilson KE, Limburg S, Duggan MK, Lawther AJ, Williams SJ, Lawrence AJ, Hale MW, Djouma E. The galanin receptor-3 antagonist, SNAP 37889, inhibits cue-induced reinstatement of alcohol-seeking and increases c-Fos expression in the nucleus accumbens shell of alcohol-preferring rats. J Psychopharmacol 2018; 32:911-921. [PMID: 29926762 DOI: 10.1177/0269881118780015] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
INTRODUCTION This study aimed to investigate the effects of the galanin-3 receptor antagonist, SNAP 37889, on c-Fos protein expression after cue-induced reinstatement of alcohol-seeking in the brains of alcohol-preferring rats. METHODS Eighteen alcohol-preferring rats were trained to self-administer 10% v/v ethanol in the presence of response-contingent cues, which was followed by extinction. Rats were then treated with SNAP 37889 (30 mg/kg, i.p.) or vehicle, before being tested for cue-induced reinstatement. Administration of SNAP 37889 reduced cue-induced reinstatement of ethanol-seeking behaviour. To examine the effect of SNAP 37889 and cue-induced reinstatement on neuronal activation, c-Fos expression was measured in subregions of the medial prefrontal cortex and nucleus accumbens. RESULTS SNAP 37889 administration increased c-Fos immunoreactivity in the nucleus accumbens shell, but was without effect in the nucleus accumbens core and the medial prefrontal cortex. Dual-label Fos/tyrosine hydroxylase immunohistochemistry was used to examine the effects of SNAP 37889 on dopamine neurons in the ventral tegmental area; however, no differences between SNAP 37889 and vehicle-treated rats were found. CONCLUSIONS These data support previous findings of galanin-3 receptor involvement in cue-induced reinstatement of alcohol-seeking behaviour, and provide novel evidence that the ability of galanin-3 receptor antagonism to attenuate cue-induced reinstatement relates to activation of the nucleus accumbens shell.
Collapse
Affiliation(s)
- Kira-Elise Wilson
- 1 School of Psychology and Public Health, La Trobe University, Melbourne, VIC, Australia
| | - Sigrid Limburg
- 1 School of Psychology and Public Health, La Trobe University, Melbourne, VIC, Australia
| | - Melissa K Duggan
- 1 School of Psychology and Public Health, La Trobe University, Melbourne, VIC, Australia
| | - Adam J Lawther
- 1 School of Psychology and Public Health, La Trobe University, Melbourne, VIC, Australia
| | - Spencer J Williams
- 2 School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, VIC, Australia
| | - Andrew J Lawrence
- 3 Florey Institute of Neuroscience and Mental Health, University of Melbourne, VIC, Australia
| | - Matthew W Hale
- 1 School of Psychology and Public Health, La Trobe University, Melbourne, VIC, Australia
| | - Elvan Djouma
- 4 School of Life Sciences, La Trobe University, Melbourne, VIC, Australia
| |
Collapse
|
8
|
Nichols IS, Jones MI, Okere C, Ananaba G, Bush B, Gray C, Brager A, Ehlen JC, Paul K. Nitrergic neurons of the dorsal raphe nucleus encode information about stress duration. PLoS One 2017; 12:e0187071. [PMID: 29125838 PMCID: PMC5681257 DOI: 10.1371/journal.pone.0187071] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Accepted: 10/12/2017] [Indexed: 11/19/2022] Open
Abstract
Nitrergic neurons of the dorsal raphe nucleus (DRN) may play a role in physiological stress responses. The caudal lateral wings (CLW) are unique compared to other rostral-caudal DRN sub-regions because they contain distinct nitric oxide (NO) synthase (NOS) populations that are independent of tryptophan hydroxylase (TPH). NOS neurons in the CLW are also highly activated during acute restraint stress. However, the effects of acute stress duration on NOS activation in the CLW are unclear. Here NADPH-d, an index of NOS activity, is used to show that sub-regions of the DRN have differential NOS activation in response to 6 hours of restraint stress in rats. We report increased NOS activity through 6 hours of restraint in the caudal lateral wings and ventromedial sub-regions. These data suggest that, NOS neurons may play a dynamic role in the response to stress duration.
Collapse
Affiliation(s)
- India S. Nichols
- Department of Biological Sciences, Clark Atlanta University, Atlanta, Georgia, United States of America
- Department of Neurobiology, Morehouse School of Medicine, Atlanta, Georgia, United States of America
| | - Mary I. Jones
- Department of Biological Sciences, Clark Atlanta University, Atlanta, Georgia, United States of America
| | - Chuma Okere
- Department of Biological Sciences, Clark Atlanta University, Atlanta, Georgia, United States of America
| | - Godwin Ananaba
- Department of Biological Sciences, Clark Atlanta University, Atlanta, Georgia, United States of America
| | - Brittany Bush
- Department of Neurobiology, Morehouse School of Medicine, Atlanta, Georgia, United States of America
| | - Cloe Gray
- Department of Neurobiology, Morehouse School of Medicine, Atlanta, Georgia, United States of America
| | - Allison Brager
- Department of Neurobiology, Morehouse School of Medicine, Atlanta, Georgia, United States of America
| | - J. Christopher Ehlen
- Department of Neurobiology, Morehouse School of Medicine, Atlanta, Georgia, United States of America
| | - Ketema Paul
- Department of Neurobiology, Morehouse School of Medicine, Atlanta, Georgia, United States of America
| |
Collapse
|
9
|
Millón C, Flores-Burgess A, Narváez M, Borroto-Escuela DO, Gago B, Santín L, Castilla-Ortega E, Narváez JÁ, Fuxe K, Díaz-Cabiale Z. The neuropeptides Galanin and Galanin(1-15) in depression-like behaviours. Neuropeptides 2017; 64:39-45. [PMID: 28196617 DOI: 10.1016/j.npep.2017.01.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 01/24/2017] [Accepted: 01/24/2017] [Indexed: 12/11/2022]
Abstract
Galanin is a 29 amino acid neuropeptide widely distributed in neurons within the central nervous system. Galanin exerts its biological activities through three different G protein-receptors and participates in a number of functions, including mood regulation. Not only Galanin but also Galanin N-terminal fragments like Galanin(1-15) are active at the central level. In this work, we review the latest findings in studies on Galanin and Galanin(1-15) in depression-related behaviours. Our focus is on animal models for depression, and we pay some attention to research data obtained in human studies. Since Serotonin (5-HT), especially through 5-HT1A, and Galanin receptors interact at both pre-and postsynaptic level, the development of drugs targeting potential GAL1-GAL2-5-HT1A heteroreceptor complexes linked to the raphe-hippocampal 5-HT neurons may represent new treatment strategies in depression.
Collapse
Affiliation(s)
- Carmelo Millón
- Universidad de Málaga, Instituto de Investigación Biomédica de Málaga, Facultad de Medicina, Departamento de Fisiología, Campus de Teatinos s/n, 29071 Málaga, Spain.
| | - Antonio Flores-Burgess
- Universidad de Málaga, Instituto de Investigación Biomédica de Málaga, Facultad de Medicina, Departamento de Fisiología, Campus de Teatinos s/n, 29071 Málaga, Spain
| | - Manuel Narváez
- Universidad de Málaga, Instituto de Investigación Biomédica de Málaga, Facultad de Medicina, Departamento de Fisiología, Campus de Teatinos s/n, 29071 Málaga, Spain
| | | | - Belén Gago
- Universidad de Málaga, Instituto de Investigación Biomédica de Málaga, Facultad de Medicina, Departamento de Fisiología, Campus de Teatinos s/n, 29071 Málaga, Spain
| | - Luis Santín
- Universidad de Málaga, Instituto de Investigación Biomédica de Málaga, Facultad de Psicología, Departamento de Psicobiología, Campus de Teatinos s/n, 29071 Málaga, Spain
| | - Estela Castilla-Ortega
- Universidad de Málaga, Instituto de Investigación Biomédica de Málaga, Facultad de Psicología, Departamento de Psicobiología, Campus de Teatinos s/n, 29071 Málaga, Spain
| | - José Ángel Narváez
- Universidad de Málaga, Instituto de Investigación Biomédica de Málaga, Facultad de Medicina, Departamento de Fisiología, Campus de Teatinos s/n, 29071 Málaga, Spain
| | - Kjell Fuxe
- Department of Neuroscience, Karolinska Institute, Stockholm, Sweden
| | - Zaida Díaz-Cabiale
- Universidad de Málaga, Instituto de Investigación Biomédica de Málaga, Facultad de Medicina, Departamento de Fisiología, Campus de Teatinos s/n, 29071 Málaga, Spain
| |
Collapse
|
10
|
GluA2-Lacking AMPA Receptors and Nitric Oxide Signaling Gate Spike-Timing-Dependent Potentiation of Glutamate Synapses in the Dorsal Raphe Nucleus. eNeuro 2017; 4:eN-NWR-0116-17. [PMID: 28580416 PMCID: PMC5454404 DOI: 10.1523/eneuro.0116-17.2017] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Revised: 05/12/2017] [Accepted: 05/18/2017] [Indexed: 12/17/2022] Open
Abstract
The dorsal raphe nucleus (DRn) receives glutamatergic inputs from numerous brain areas that control the function of DRn serotonin (5-HT) neurons. By integrating these synaptic inputs, 5-HT neurons modulate a plethora of behaviors and physiological functions. However, it remains unknown whether the excitatory inputs onto DRn 5-HT neurons can undergo activity-dependent change of strength, as well as the mechanisms that control their plasticity. Here, we describe a novel form of spike-timing–dependent long-term potentiation (tLTP) of glutamate synapses onto rat DRn 5-HT neurons. This form of synaptic plasticity is initiated by an increase in postsynaptic intracellular calcium but is maintained by a persistent increase in the probability of glutamate release. The tLTP of glutamate synapses onto DRn 5-HT is independent of NMDA receptors but requires the activation of calcium-permeable AMPA receptors and voltage-dependent calcium channels. The presynaptic expression of the tLTP is mediated by the retrograde messenger nitric oxide (NO) and activation of cGMP/PKG pathways. Collectively, these results indicate that glutamate synapses in the DRn undergo activity-dependent synaptic plasticity gated by NO signaling and unravel a previously unsuspected role of NO in controlling synaptic function and plasticity in the DRn.
Collapse
|
11
|
Galanin subtype 1 and subtype 2 receptors mediate opposite anxiety-like effects in the rat dorsal raphe nucleus. Behav Brain Res 2016; 314:125-33. [DOI: 10.1016/j.bbr.2016.08.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Revised: 08/01/2016] [Accepted: 08/03/2016] [Indexed: 01/09/2023]
|
12
|
Wang P, Li H, Barde S, Zhang MD, Sun J, Wang T, Zhang P, Luo H, Wang Y, Yang Y, Wang C, Svenningsson P, Theodorsson E, Hökfelt TGM, Xu ZQD. Depression-like behavior in rat: Involvement of galanin receptor subtype 1 in the ventral periaqueductal gray. Proc Natl Acad Sci U S A 2016; 113:E4726-35. [PMID: 27457954 PMCID: PMC4987783 DOI: 10.1073/pnas.1609198113] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The neuropeptide galanin coexists in rat brain with serotonin in the dorsal raphe nucleus and with noradrenaline in the locus coeruleus (LC), and it has been suggested to be involved in depression. We studied rats exposed to chronic mild stress (CMS), a rodent model of depression. As expected, these rats showed several endophenotypes relevant to depression-like behavior compared with controls. All these endophenotypes were normalized after administration of a selective serotonin reuptake inhibitor. The transcripts for galanin and two of its receptors, galanin receptor 1 (GALR1) and GALR2, were analyzed with quantitative real-time PCR using laser capture microdissection in the following brain regions: the hippocampal formation, LC, and ventral periaqueductal gray (vPAG). Only Galr1 mRNA levels were significantly increased, and only in the latter region. After knocking down Galr1 in the vPAG with an siRNA technique, all parameters of the depressive behavioral phenotype were similar to controls. Thus, the depression-like behavior in rats exposed to CMS is likely related to an elevated expression of Galr1 in the vPAG, suggesting that a GALR1 antagonist could have antidepressant effects.
Collapse
Affiliation(s)
- Peng Wang
- 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 100069, China
| | - Hui Li
- 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 100069, China
| | - Swapnali Barde
- Department of Neuroscience, Karolinska Institutet, SE-17177 Stockholm, Sweden
| | - Ming-Dong Zhang
- Department of Neuroscience, Karolinska Institutet, SE-17177 Stockholm, Sweden; Division of Molecular Neurobiology, Department of Biochemistry and Biophysics, Karolinska Institutet, SE-17177 Stockholm, Sweden
| | - Jing Sun
- 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 100069, China
| | - Tong Wang
- 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 100069, China
| | - Pan Zhang
- 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 100069, China
| | - Hanjiang Luo
- 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 100069, China
| | - Yongjun Wang
- Anding Hospital, Capital Medical University, Beijing 100088, China
| | - Yutao Yang
- 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 100069, China
| | - Chuanyue Wang
- Anding Hospital, Capital Medical University, Beijing 100088, China
| | - Per Svenningsson
- Center for Molecular Medicine, Department of Neurology and Clinical Neuroscience, Karolinska Institutet and Karolinska University Hospital, SE-17176 Stockholm, Sweden
| | - Elvar Theodorsson
- Department of Clinical Chemistry and Department of Clinical and Experimental Medicine, Linkoping University, SE-58183 Linkoping, Sweden
| | - Tomas G M Hökfelt
- Department of Neuroscience, Karolinska Institutet, SE-17177 Stockholm, Sweden;
| | - Zhi-Qing David Xu
- 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 100069, China;
| |
Collapse
|
13
|
Petschner P, Juhasz G, Tamasi V, Adori C, Tothfalusi L, Hökfelt T, Bagdy G. Chronic venlafaxine treatment fails to alter the levels of galanin system transcripts in normal rats. Neuropeptides 2016; 57:65-70. [PMID: 26891823 DOI: 10.1016/j.npep.2016.01.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Revised: 01/22/2016] [Accepted: 01/31/2016] [Indexed: 11/16/2022]
Abstract
It is widely accepted that efficacy and speed of current antidepressants' therapeutic effect are far from optimal. Thus, there is a need for the development of antidepressants with new mechanisms of action. The neuropeptide galanin and its receptors (GalR1, GalR2 and GalR3) are among the promising targets. However, it is not clear whether or not the galanin system is involved in the antidepressant effect exerted by the currently much used inhibitors of the reuptake of serotonin and/or noradrenaline. To answer this question we administered the selective serotonin and noradrenaline reuptake inhibitor (SNRI) venlafaxine (40mg/kg/day via osmotic minipumps) to normal rats and examined the levels of the transcripts for galanin and GalR1-3 after a 3-week venlafaxine treatment in the dorsal raphe, hippocampus and frontal cortex. These areas are known to be involved in the effects of antidepressants and in depression itself. Venlafaxine failed to alter the expression of any of the galanin system genes in these areas. Our results show that one of the most efficient, currently used SNRIs does not alter transcript levels of galanin or its three receptors in normal rats. These findings suggest that the pro- and antidepressive-like effects of galanin reported in animal experiments may employ a novel mechanism(s).
Collapse
Affiliation(s)
- Peter Petschner
- Department of Pharmacodynamics, Semmelweis University, H-1089, Nagyvarad ter 4., Budapest, Hungary; MTA-SE Neuropsychopharmacology & Neurochemistry Research Group, H-1089, Nagyvarad ter 4., Budapest, Hungary
| | - Gabriella Juhasz
- Department of Pharmacodynamics, Semmelweis University, H-1089, Nagyvarad ter 4., Budapest, Hungary; MTA-SE Neuropsychopharmacology & Neurochemistry Research Group, H-1089, Nagyvarad ter 4., Budapest, Hungary; MTA-SE-NAP B Genetic Brain Imaging Migraine Research Group, Hungarian Academy of Sciences, Semmelweis University, Hungary
| | - Viola Tamasi
- Department of Genetics-, Cell and Immunobiology, Semmelweis University, H-1089, Nagyvarad ter 4., Budapest, Hungary
| | - Csaba Adori
- Department of Pharmacodynamics, Semmelweis University, H-1089, Nagyvarad ter 4., Budapest, Hungary; Retzius Laboratory, Department of Neuroscience, Karolinska Institutet, Retzius väg 8, 17177, Stockholm, Sweden
| | - Laszlo Tothfalusi
- Department of Pharmacodynamics, Semmelweis University, H-1089, Nagyvarad ter 4., Budapest, Hungary
| | - Tomas Hökfelt
- Retzius Laboratory, Department of Neuroscience, Karolinska Institutet, Retzius väg 8, 17177, Stockholm, Sweden
| | - Gyorgy Bagdy
- Department of Pharmacodynamics, Semmelweis University, H-1089, Nagyvarad ter 4., Budapest, Hungary; MTA-SE Neuropsychopharmacology & Neurochemistry Research Group, H-1089, Nagyvarad ter 4., Budapest, Hungary.
| |
Collapse
|
14
|
Kawa L, Barde S, Arborelius UP, Theodorsson E, Agoston D, Risling M, Hökfelt T. Expression of galanin and its receptors are perturbed in a rodent model of mild, blast-induced traumatic brain injury. Exp Neurol 2016; 279:159-167. [PMID: 26928087 DOI: 10.1016/j.expneurol.2016.02.019] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Revised: 02/22/2016] [Accepted: 02/24/2016] [Indexed: 01/05/2023]
Abstract
The symptomatology, mood and cognitive disturbances seen in post-traumatic stress disorder (PTSD) and mild blast-induced traumatic brain injury (mbTBI) overlap considerably. However the pathological mechanisms underlying the two conditions are currently unknown. The neuropeptide galanin has been suggested to play a role in the development of stress and mood disorders. Here we applied bio- and histochemical methods with the aim to elucidate the nature of any changes in the expression of galanin and its receptors in a rodent model of mbTBI. In situ hybridization and quantitative polymerase chain reaction studies revealed significant, injury-induced changes, in some cases lasting at least for one week, in the mRNA levels of galanin and/or its three receptors, galanin receptor 1-3 (GalR1-3). Such changes were seen in several forebrain regions, and the locus coeruleus. In the ventral periaqueductal gray GalR1 mRNA levels were increased, while GalR2 were decreased. Analysis of galanin peptide levels using radioimmunoassay demonstrated an increase in several brain regions including the locus coeruleus, dorsal hippocampal formation and amygdala. These findings suggest a role for the galanin system in the endogenous response to mbTBI, and that pharmacological studies of the effects of activation or inhibition of different galanin receptors in combination with functional assays of behavioral recovery may reveal promising targets for new therapeutic strategies in mbTBI.
Collapse
Affiliation(s)
- Lizan Kawa
- Department of Neuroscience, Karolinska Institutet, Retzius väg 8, SE 171 77 Stockholm, Sweden.
| | - Swapnali Barde
- Department of Neuroscience, Karolinska Institutet, Retzius väg 8, SE 171 77 Stockholm, Sweden
| | - Ulf P Arborelius
- Department of Neuroscience, Karolinska Institutet, Retzius väg 8, SE 171 77 Stockholm, Sweden
| | - Elvar Theodorsson
- Department of Clinical Chemistry, Linköping University, Linköping, Sweden
| | - Denes Agoston
- Department of Neuroscience, Karolinska Institutet, Retzius väg 8, SE 171 77 Stockholm, Sweden; Department of Anatomy, Physiology and Genetics, The Uniformed Services University, 4301 Jones Bridge Road, Bethesda, MD 20814, United States
| | - Mårten Risling
- Department of Neuroscience, Karolinska Institutet, Retzius väg 8, SE 171 77 Stockholm, Sweden.
| | - Tomas Hökfelt
- Department of Neuroscience, Karolinska Institutet, Retzius väg 8, SE 171 77 Stockholm, Sweden
| |
Collapse
|
15
|
Lang R, Gundlach AL, Holmes FE, Hobson SA, Wynick D, Hökfelt T, Kofler B. Physiology, signaling, and pharmacology of galanin peptides and receptors: three decades of emerging diversity. Pharmacol Rev 2015; 67:118-75. [PMID: 25428932 DOI: 10.1124/pr.112.006536] [Citation(s) in RCA: 218] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Galanin was first identified 30 years ago as a "classic neuropeptide," with actions primarily as a modulator of neurotransmission in the brain and peripheral nervous system. Other structurally-related peptides-galanin-like peptide and alarin-with diverse biologic actions in brain and other tissues have since been identified, although, unlike galanin, their cognate receptors are currently unknown. Over the last two decades, in addition to many neuronal actions, a number of nonneuronal actions of galanin and other galanin family peptides have been described. These include actions associated with neural stem cells, nonneuronal cells in the brain such as glia, endocrine functions, effects on metabolism, energy homeostasis, and paracrine effects in bone. Substantial new data also indicate an emerging role for galanin in innate immunity, inflammation, and cancer. Galanin has been shown to regulate its numerous physiologic and pathophysiological processes through interactions with three G protein-coupled receptors, GAL1, GAL2, and GAL3, and signaling via multiple transduction pathways, including inhibition of cAMP/PKA (GAL1, GAL3) and stimulation of phospholipase C (GAL2). In this review, we emphasize the importance of novel galanin receptor-specific agonists and antagonists. Also, other approaches, including new transgenic mouse lines (such as a recently characterized GAL3 knockout mouse) represent, in combination with viral-based techniques, critical tools required to better evaluate galanin system physiology. These in turn will help identify potential targets of the galanin/galanin-receptor systems in a diverse range of human diseases, including pain, mood disorders, epilepsy, neurodegenerative conditions, diabetes, and cancer.
Collapse
Affiliation(s)
- Roland Lang
- Department of Dermatology (R.L.) and Laura Bassi Centre of Expertise, Department of Pediatrics (B.K.), Paracelsus Private Medical University, Salzburg, Austria; The Florey Institute of Neuroscience and Mental Health, and Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, Victoria, Australia (A.L.G.); Schools of Physiology and Pharmacology and Clinical Sciences, Bristol University, Bristol, United Kingdom (F.E.H., S.A.H., D.W.); and Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden (T.H.)
| | - Andrew L Gundlach
- Department of Dermatology (R.L.) and Laura Bassi Centre of Expertise, Department of Pediatrics (B.K.), Paracelsus Private Medical University, Salzburg, Austria; The Florey Institute of Neuroscience and Mental Health, and Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, Victoria, Australia (A.L.G.); Schools of Physiology and Pharmacology and Clinical Sciences, Bristol University, Bristol, United Kingdom (F.E.H., S.A.H., D.W.); and Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden (T.H.)
| | - Fiona E Holmes
- Department of Dermatology (R.L.) and Laura Bassi Centre of Expertise, Department of Pediatrics (B.K.), Paracelsus Private Medical University, Salzburg, Austria; The Florey Institute of Neuroscience and Mental Health, and Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, Victoria, Australia (A.L.G.); Schools of Physiology and Pharmacology and Clinical Sciences, Bristol University, Bristol, United Kingdom (F.E.H., S.A.H., D.W.); and Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden (T.H.)
| | - Sally A Hobson
- Department of Dermatology (R.L.) and Laura Bassi Centre of Expertise, Department of Pediatrics (B.K.), Paracelsus Private Medical University, Salzburg, Austria; The Florey Institute of Neuroscience and Mental Health, and Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, Victoria, Australia (A.L.G.); Schools of Physiology and Pharmacology and Clinical Sciences, Bristol University, Bristol, United Kingdom (F.E.H., S.A.H., D.W.); and Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden (T.H.)
| | - David Wynick
- Department of Dermatology (R.L.) and Laura Bassi Centre of Expertise, Department of Pediatrics (B.K.), Paracelsus Private Medical University, Salzburg, Austria; The Florey Institute of Neuroscience and Mental Health, and Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, Victoria, Australia (A.L.G.); Schools of Physiology and Pharmacology and Clinical Sciences, Bristol University, Bristol, United Kingdom (F.E.H., S.A.H., D.W.); and Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden (T.H.)
| | - Tomas Hökfelt
- Department of Dermatology (R.L.) and Laura Bassi Centre of Expertise, Department of Pediatrics (B.K.), Paracelsus Private Medical University, Salzburg, Austria; The Florey Institute of Neuroscience and Mental Health, and Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, Victoria, Australia (A.L.G.); Schools of Physiology and Pharmacology and Clinical Sciences, Bristol University, Bristol, United Kingdom (F.E.H., S.A.H., D.W.); and Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden (T.H.)
| | - Barbara Kofler
- Department of Dermatology (R.L.) and Laura Bassi Centre of Expertise, Department of Pediatrics (B.K.), Paracelsus Private Medical University, Salzburg, Austria; The Florey Institute of Neuroscience and Mental Health, and Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, Victoria, Australia (A.L.G.); Schools of Physiology and Pharmacology and Clinical Sciences, Bristol University, Bristol, United Kingdom (F.E.H., S.A.H., D.W.); and Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden (T.H.)
| |
Collapse
|
16
|
Herculano AM, Maximino C. Serotonergic modulation of zebrafish behavior: towards a paradox. Prog Neuropsychopharmacol Biol Psychiatry 2014; 55:50-66. [PMID: 24681196 DOI: 10.1016/j.pnpbp.2014.03.008] [Citation(s) in RCA: 106] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Revised: 03/12/2014] [Accepted: 03/13/2014] [Indexed: 12/22/2022]
Abstract
Due to the fish-specific genome duplication event (~320-350 mya), some genes which code for serotonin proteins were duplicated in teleosts; this duplication event was preceded by a reorganization of the serotonergic system, with the appearance of the raphe nuclei (dependent on the isthmus organizer) and prosencephalic nuclei, including the paraventricular and pretectal complexes. With the appearance of amniotes, duplicated genes were lost, and the serotonergic system was reduced to a more complex raphe system. From a comparative point of view, then, the serotonergic system of zebrafish and that of mammals shows many important differences. However, many different behavioral functions of serotonin, as well as the effects of drugs which affect the serotonergic system, seem to be conserved among species. For example, in both zebrafish and rodents acute serotonin reuptake inhibitors (SSRIs) seem to increase anxiety-like behavior, while chronic SSRIs decrease it; drugs which act at the 5-HT1A receptor seem to decrease anxiety-like behavior in both zebrafish and rodents. In this article, we will expose this paradox, reviewing the chemical neuroanatomy of the zebrafish serotonergic system, followed by an analysis of the role of serotonin in zebrafish fear/anxiety, stress, aggression and the effects of psychedelic drugs.
Collapse
Affiliation(s)
- Anderson Manoel Herculano
- Neuroendocrinology Laboratory, Biological Sciences Institute, Federal University of Pará, Belém, PA, Brazil; "Frederico Graeff" Neurosciences and Behavior Laboratory, Department of Morphology and Physiological Sciences, Biological and Health Sciences Center, State University of Pará, Marabá, PA, Brazil
| | - Caio Maximino
- "Frederico Graeff" Neurosciences and Behavior Laboratory, Department of Morphology and Physiological Sciences, Biological and Health Sciences Center, State University of Pará, Marabá, PA, Brazil; International Zebrafish Neuroscience Research Consortium, United States.
| |
Collapse
|
17
|
Corteen NL, Carter JA, Rudolph U, Belelli D, Lambert JJ, Swinny JD. Localisation and stress-induced plasticity of GABAA receptor subunits within the cellular networks of the mouse dorsal raphe nucleus. Brain Struct Funct 2014; 220:2739-63. [PMID: 24973971 DOI: 10.1007/s00429-014-0824-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Accepted: 06/11/2014] [Indexed: 01/28/2023]
Abstract
The dorsal raphe nucleus (DRN) provides the major source of serotonin to the central nervous system (CNS) and modulates diverse neural functions including mood. Furthermore, DRN cellular networks are engaged in the stress-response at the CNS level allowing for adaptive behavioural responses, whilst stress-induced dysregulation of DRN and serotonin release is implicated in psychiatric disorders. Therefore, identifying the molecules regulating DRN activity is fundamental to understand DRN function in health and disease. GABAA receptors (GABAARs) allow for brain region, cell type and subcellular domain-specific GABA-mediated inhibitory currents and are thus key regulators of neuronal activity. Yet, the GABAAR subtypes expressed within the neurochemically diverse cell types of the mouse DRN are poorly described. In this study, immunohistochemistry and confocal microscopy revealed that all serotonergic neurons expressed immunoreactivity for the GABAAR alpha2 and 3 subunits, although the respective signals were co-localised to varying degrees with inhibitory synaptic marker proteins. Only a topographically located sub-population of serotonergic neurons exhibited GABAAR alpha1 subunit immunoreactivity. However, all GABAergic as well as non-GABAergic, non-serotonergic neurons within the DRN expressed GABAAR alpha1 subunit immunoreactivity. Intriguingly, immunoreactivity for the GABAAR gamma2 subunit was enriched on GABAergic rather than serotonergic neurons. Finally, repeated restraint stress increased the expression of the GABAAR alpha3 subunit at the mRNA and protein level. The study demonstrates the identity and location of distinct GABAAR subunits within the cellular networks of the mouse DRN and that stress impacts on the expression levels of particular subunits at the gene and protein level.
Collapse
Affiliation(s)
- Nicole L Corteen
- Institute for Biomedical and Biomolecular Sciences, School of Pharmacy and Biomedical Sciences, University of Portsmouth, St Michael's Building, White Swan Road, Portsmouth, PO1 2DT, UK,
| | | | | | | | | | | |
Collapse
|
18
|
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
| |
Collapse
|
19
|
Loughridge AB, Greenwood BN, Day HEW, McQueen MB, Fleshner M. Microarray analyses reveal novel targets of exercise-induced stress resistance in the dorsal raphe nucleus. Front Behav Neurosci 2013; 7:37. [PMID: 23717271 PMCID: PMC3650681 DOI: 10.3389/fnbeh.2013.00037] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Accepted: 04/18/2013] [Indexed: 12/18/2022] Open
Abstract
Serotonin (5-HT) is implicated in the development of stress-related mood disorders in humans. Physical activity reduces the risk of developing stress-related mood disorders, such as depression and anxiety. In rats, 6 weeks of wheel running protects against stress-induced behaviors thought to resemble symptoms of human anxiety and depression. The mechanisms by which exercise confers protection against stress-induced behaviors, however, remain unknown. One way by which exercise could generate stress resistance is by producing plastic changes in gene expression in the dorsal raphe nucleus (DRN). The DRN has a high concentration of 5-HT neurons and is implicated in stress-related mood disorders. The goal of the current experiment was to identify changes in the expression of genes that could be novel targets of exercise-induced stress resistance in the DRN. Adult, male F344 rats were allowed voluntary access to running wheels for 6 weeks; exposed to inescapable stress or no stress; and sacrificed immediately and 2 h after stressor termination. Laser capture micro dissection selectively sampled the DRN. mRNA expression was measured using the whole genome Affymetrix microarray. Comprehensive data analyses of gene expression included differential gene expression, log fold change (LFC) contrast analyses with False Discovery Rate correction, KEGG and Wiki Web Gestalt pathway enrichment analyses, and Weighted Gene Correlational Network Analysis (WGCNA). Our results suggest that physically active rats exposed to stress modulate expression of twice the number of genes, and display a more rapid and strongly coordinated response, than sedentary rats. Bioinformatics analyses revealed several potential targets of stress resistance including genes that are related to immune processes, tryptophan metabolism, and circadian/diurnal rhythms.
Collapse
Affiliation(s)
- Alice B Loughridge
- Department of Integrative Physiology, University of Colorado Boulder Boulder, CO, USA
| | | | | | | | | |
Collapse
|
20
|
Distinct features of neurotransmitter systems in the human brain with focus on the galanin system in locus coeruleus and dorsal raphe. Proc Natl Acad Sci U S A 2013; 110:E536-45. [PMID: 23341594 DOI: 10.1073/pnas.1221378110] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Using riboprobe in situ hybridization, we studied the localization of the transcripts for the neuropeptide galanin and its receptors (GalR1-R3), tryptophan hydroxylase 2, tyrosine hydroxylase, and nitric oxide synthase as well as the three vesicular glutamate transporters (VGLUT 1-3) in the locus coeruleus (LC) and the dorsal raphe nucleus (DRN) regions of postmortem human brains. Quantitative real-time PCR (qPCR) was used also. Galanin and GalR3 mRNA were found in many noradrenergic LC neurons, and GalR3 overlapped with serotonin neurons in the DRN. The qPCR analysis at the LC level ranked the transcripts in the following order in the LC: galanin >> GalR3 >> GalR1 > GalR2; in the DRN the ranking was galanin >> GalR3 >> GalR1 = GalR2. In forebrain regions the ranking was GalR1 > galanin > GalR2. VGLUT1 and -2 were strongly expressed in the pontine nuclei but could not be detected in LC or serotonin neurons. VGLUT2 transcripts were found in very small, nonpigmented cells in the LC and in the lateral and dorsal aspects of the periaqueductal central gray. Nitric oxide synthase was not detected in serotonin neurons. These findings show distinct differences between the human brain and rodents, especially rat, in the distribution of the galanin system and some other transmitter systems. For example, GalR3 seems to be the important galanin receptor in both the human LC and DRN versus GalR1 and -2 in the rodent brain. Such knowledge may be important when considering therapeutic principles and drug development.
Collapse
|
21
|
Nicotine withdrawal upregulates nitrergic and galaninergic activity in the rat dorsal raphe nucleus and locus coeruleus. Neurosci Lett 2013; 536:29-34. [PMID: 23305719 DOI: 10.1016/j.neulet.2012.12.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Revised: 11/30/2012] [Accepted: 12/03/2012] [Indexed: 11/23/2022]
Abstract
The dorsal raphe nucleus (DRN), a major source of forebrain serotonin, mediates various neural functions including anxiety. The nucleus locus coeruleus (LC) is likewise involved in mediating central components of the stress response and anxiety. An anxiety-reducing effect is widely believed to underlie many cases of nicotine dependence. While much is known about nicotine-serotonin interactions, little is known about how nicotine engages the DRN non-serotonergic domain in specific physiological functions that influence organismal behavior. The aim of this study was to determine how chronic nicotine withdrawal influences neuronal nitric oxide (NO) synthase (nNOS) and galanin immunoreactivity in the DRN and LC of adult rats. Compared with saline, nicotine increased nicotinamide adenine dinucleotide phosphate diaphorase profiles within distinct DRN subregions and also enhanced intensity in nNOS and galanin cell bodies in the rostral DRN as well as galanin in the LC. Nicotine-induced nNOS/galanin staining of somata was abundant in the rostral ventromedial DRN. Galanin-positive terminals surrounded nNOS-containing cell bodies in the DRN lateral wing subregions. These observations suggest that the DRN NOS-galanin domain and galanin in the LC are engaged in the organism's neural adaptation to chronic nicotine exposure. Hence NO and galanin synthesized or released within the DRN and LC or at the respective target sites might regulate the whole animal behavioral response to nicotine exposure.
Collapse
|
22
|
Bajic D, Berde CB, Commons KG. Periaqueductal gray neuroplasticity following chronic morphine varies with age: role of oxidative stress. Neuroscience 2012; 226:165-77. [PMID: 22999971 PMCID: PMC3489988 DOI: 10.1016/j.neuroscience.2012.09.028] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2012] [Revised: 09/09/2012] [Accepted: 09/11/2012] [Indexed: 12/30/2022]
Abstract
The development of tolerance to the antinociceptive effects of morphine has been associated with networks within ventrolateral periaqueductal gray (vlPAG) and separately, nitric oxide signaling. Furthermore, it is known that the mechanisms that underlie tolerance differ with age. In this study, we used a rat model of antinociceptive tolerance to morphine at two ages, postnatal day (PD) 7 and adult, to determine if changes in the vlPAG related to nitric oxide signaling produced by chronic morphine exposure were age-dependent. Three pharmacological groups were analyzed: control, acute morphine, and chronic morphine group. Either morphine (10mg/kg) or equal volume of normal saline was given subcutaneously twice daily for 6½ days. Animals were analyzed for morphine dose-response using Hot Plate test. The expression of several genes associated with nitric oxide metabolism was evaluated using rtPCR. In addition, the effect of morphine exposure on immunohistochemistry for Fos, and nNOS as well as nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) reaction at the vlPAG were measured. In both age groups acute morphine activated Fos in the vlPAG, and this effect was attenuated by chronic morphine, specifically in the vlPAG at the level of the laterodorsal tegmental nucleus (LDTg). In adults, but not PD7 rats, chronic morphine administration was associated with activation of nitric oxide function. In contrast, changes in the gene expression of PD7 rats suggested superoxide and peroxide metabolisms may be engaged. These data indicate that there is supraspinal neuroplasticity following morphine administration as early as PD7. Furthermore, oxidative stress pathways associated with chronic morphine exposure appear age-specific.
Collapse
Affiliation(s)
- D Bajic
- Department of Anesthesiology, Perioperative and Pain Medicine, Boston Children's Hospital, and Department of Anaesthesia, Harvard Medical School, Boston, MA 02115, USA.
| | | | | |
Collapse
|
23
|
Bajo M, Madamba SG, Lu X, Sharkey LM, Bartfai T, Siggins GR. Receptor subtype-dependent galanin actions on gamma-aminobutyric acidergic neurotransmission and ethanol responses in the central amygdala. Addict Biol 2012; 17:694-705. [PMID: 21955024 DOI: 10.1111/j.1369-1600.2011.00360.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The neuropeptide galanin and its three receptor subtypes (GalR1-3) are expressed in the central amygdala (CeA), a brain region involved in stress- and anxiety-related behaviors, as well as alcohol dependence. Galanin also has been suggested to play a role in alcohol intake and alcohol dependence. We examined the effects of galanin in CeA slices from wild-type and knockout (KO) mice deficient of GalR2 and both GalR1 and GalR2 receptors. Galanin had dual effects on gamma-aminobutyric acid (GABA)-ergic transmission, decreasing the amplitudes of pharmacologically isolated GABAergic inhibitory postsynaptic potentials (IPSPs) in over half of CeA neurons but augmenting IPSPs in the others. The increase in IPSP size was absent after superfusion of the GalR3 antagonist SNAP 37889, whereas the IPSP depression was absent in CeA neurons of GalR1 × GalR2 double KO and GalR2 KO mice. Paired-pulse facilitation studies showed weak or infrequent effects of galanin on GABA release. Thus, galanin may act postsynaptically through GalR3 to augment GABAergic transmission in some CeA neurons, whereas GalR2 receptors likely are involved in the depression of IPSPs. Co-superfusion of ethanol, which augments IPSPs presynaptically, together with galanin caused summated effects of ethanol and galanin in those CeA neurons showing galanin-augmented IPSPs, suggesting the two agents act via different mechanisms in this population. However, in neurons showing IPSP-diminishing galanin effects, galanin blunted the ethanol effects, suggesting a preemptive effect of galanin. These findings may increase understanding of the complex cellular mechanisms that underlie the anxiety-related behavioral effects of galanin and ethanol in CeA.
Collapse
Affiliation(s)
- Michal Bajo
- Molecular and Integrative Neurosciences Department, The Scripps Research Institute, La Jolla, CA 92037, USA
| | | | | | | | | | | |
Collapse
|
24
|
Rovin ML, Boss-Williams KA, Alisch RS, Ritchie JC, Weinshenker D, West CH, Weiss JM. Influence of chronic administration of antidepressant drugs on mRNA for galanin, galanin receptors, and tyrosine hydroxylase in catecholaminergic and serotonergic cell-body regions in rat brain. Neuropeptides 2012; 46:81-91. [PMID: 22317959 PMCID: PMC3759228 DOI: 10.1016/j.npep.2012.01.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Revised: 11/11/2011] [Accepted: 01/02/2012] [Indexed: 11/19/2022]
Abstract
Activity of locus coeruleus (LC) neurons and release of the peptide galanin (GAL), which is colocalized with norepinephrine (NE) in LC neurons, has been implicated in depression and, conversely, in antidepressant action. The present study examined the influence of chronic administration (for 14days, via subcutaneously-implanted minipump) of antidepressant (AD) drugs representing three different classes (tricyclic [desipramine], selective serotonin reuptake inhibitor [SSRI] [paroxetine], and monoamine oxidase inhibitor [MAOI] [phenelzine]) on mRNA for GAL, GAL receptors (GalR1, GalR2, and GalR3), and tyrosine hydroxylase (TH), the rate-limiting enzyme for NE synthesis, in four brain regions--LC, A1/C1, dorsal raphe (DRN), and ventral tegmentum (VTA) of rats. Consistent with previous findings that chronic administration of AD drugs decreases activity of LC neurons, administration of AD drugs reduced mRNA for both GAL and TH in LC neurons. GAL and TH mRNA in LC neurons was highly correlated. AD drugs also reduced GAL and TH mRNA in A1/C1 and VTA but effects were smaller than in LC. The largest change in mRNA for GAL receptors produced by AD administration was to decrease mRNA for GalR2 receptors in the VTA region. Also, mRNA for GalR2 and GalR3 receptors was significantly (positively) correlated in all three predominantly catecholaminergic brain regions (LC, A1/C1, and VTA). Relative to these three brain regions, unique effects were seen in the DRN region, with the SSRI elevating GAL mRNA and with mRNA for GalR1 and GalR3 being highly correlated in this brain region. The findings show that chronic administration of AD drugs, which produces effective antidepressant action, results in changes in mRNA for GAL, GAL receptors, and TH in brain regions that likely participate in depression and antidepressant effects.
Collapse
Affiliation(s)
| | | | | | - James C. Ritchie
- Department of Pathology Emory University School of Medicine Atlanta, GA, USA
| | | | | | | |
Collapse
|
25
|
Functional organization of the dorsal raphe efferent system with special consideration of nitrergic cell groups. J Chem Neuroanat 2011; 41:281-93. [PMID: 21640185 DOI: 10.1016/j.jchemneu.2011.05.008] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2011] [Revised: 05/10/2011] [Accepted: 05/16/2011] [Indexed: 11/22/2022]
Abstract
The serotonin (5HT) system of the brain is involved in many CNS functions including sensory perception, stress responses and psychological disorders such as anxiety and depression. Of the nine 5HT nuclei located in the mammalian brain, the dorsal raphe nucleus (DRN) has the most extensive forebrain connectivity and is implicated in the manifestation of stress-related psychological disturbances. Initial investigations of DRN efferent connections failed to acknowledge the rostrocaudal and mediolateral organization of the nucleus or its neurochemical heterogeneity. More recent studies have focused on the non-5HT contingent of DRN cells and have revealed an intrinsic intranuclear organization of the DRN which has specific implications for sensory signal processing and stress responses. Of particular interest are spatially segregated subsets of nitric oxide producing neurons that are activated by stressors and that have unique efferent projection fields. In this regard, both the midline and lateral wing subregions of the DRN have emerged as prominent loci for future investigation of nitric oxide function and modulation of sensory- and stressor-related signals in the DRN and coinciding terminal fields.
Collapse
|
26
|
Lu Y, Simpson KL, Weaver KJ, Lin RCS. Coexpression of serotonin and nitric oxide in the raphe complex: cortical versus subcortical circuit. Anat Rec (Hoboken) 2011; 293:1954-65. [PMID: 20734426 DOI: 10.1002/ar.21222] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Several lines of evidence have implicated a direct reciprocal interaction between serotonin and nitric oxide (NO). The goal of this investigation was, therefore, to examine the coexpression of tryptophan hydroxylase (TPH; the rate limiting enzyme for the synthesis of serotonin) and neuronal NO synthase (nNOS) in the ascending cortical projecting raphe nuclei (B6-B9 subgroups), when compared with the descending spinal cord projecting raphe nuclei (B1-B3 subgroups). Our data demonstrated that: (1) a significant number of raphe-cortical projecting neurons was identified not only in the midline subgroup of dorsal raphe (B6, 7) but also in the median raphe (B8), as well as in the supralemniscal nucleus (B9); (2) serotonergic cortical projecting neurons from these three raphe nuclei exhibited a high (>80%) percentage of coexpression with nNOS immunoreactivity; (3) similarly, serotonin transporter immunoreactive fibers in the medial prefrontal cortex were also double-labeled with nNOS immunoreactivity; (4) in contrast, the descending spinal cord projecting raphe nuclei revealed only TPH but not nNOS immunoreactivity. Our present findings suggest the existence of a direct interaction between serotonin and NO in the ascending cortical projecting raphe system. In contrast, a different strategy appears to operate the descending spinal cord projecting raphe system.
Collapse
Affiliation(s)
- Yuefeng Lu
- Department of Biology, Tougaloo College, Tougaloo, Mississippi, USA
| | | | | | | |
Collapse
|
27
|
Fu W, Le Maître E, Fabre V, Bernard JF, David Xu ZQ, Hökfelt T. Chemical neuroanatomy of the dorsal raphe nucleus and adjacent structures of the mouse brain. J Comp Neurol 2010; 518:3464-94. [PMID: 20589909 DOI: 10.1002/cne.22407] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Serotonin neurons play a major role in many normal and pathological brain functions. In the rat these neurons have a varying number of cotransmitters, including neuropeptides. Here we studied, with histochemical techniques, the relation between serotonin, some other small-molecule transmitters, and a number of neuropeptides in the dorsal raphe nucleus (DRN) and the adjacent ventral periaqueductal gray (vPAG) of mouse, an important question being to establish possible differences from rat. Even if similarly distributed, the serotonin neurons in mouse lacked the extensive coexpression of nitric oxide synthase and galanin seen in rat. Although partly overlapping in the vPAG, no evidence was obtained for the coexistence of serotonin with dopamine, substance P, cholecystokinin, enkephalin, somatostatin, neurotensin, dynorphin, thyrotropin-releasing hormone, or corticotropin-releasing hormone. However, some serotonin neurons expressed the gamma-aminobutyric acid (GABA)-synthesizing enzyme glutamic acid decarboxylase (GAD). Work in other laboratories suggests that, as in rat, serotonin neurons in the mouse midline DRN express the vesicular glutamate transporter 3, presumably releasing glutamate. Our study also shows that many of the neuropeptides studied (substance P, galanin, neurotensin, dynorphin, and corticotropin-releasing factor) are present in nerve terminal networks of varying densities close to the serotonin neurons, and therefore may directly or indirectly influence these cells. The apparently low numbers of coexisting messengers in mouse serotonin neurons, compared to rat, indicate considerable species differences with regard to the chemical neuronatomy of the DRN. Thus, extrapolation of DRN physiology, and possibly pathology, from rat to mouse, and even human, should be made with caution.
Collapse
Affiliation(s)
- Wenyu Fu
- Department of Neuroscience, Karolinska Institutet, 17177 Stockholm, Sweden
| | | | | | | | | | | |
Collapse
|
28
|
Jahanshahi A, Lim LW, Steinbusch HWM, Visser-Vandewalle V, Temel Y. Buspirone-induced changes in the serotonergic and non-serotonergic cells in the dorsal raphe nucleus of rats. Neurosci Lett 2010; 473:136-40. [PMID: 20178829 DOI: 10.1016/j.neulet.2010.02.038] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2009] [Revised: 02/11/2010] [Accepted: 02/15/2010] [Indexed: 11/25/2022]
Abstract
Buspirone, a 5-HT (5-hydroxytryptamine, serotonin)(1A) partial agonist, is being used as an anxiolytic drug. The mechanism of action is explained by an effect on the 5-HT system. The main source of 5-HT in the forebrain is the dorsal raphe nucleus (DRN). However, there are also other populations of non-5-HT neurons in the DRN. Here, we investigated the effect of acute and chronic buspirone treatments on the 5-HT and non-5-HT cells, the neuronal nitric oxide synthase (nNOS) and tyrosine hydroxylase (TH) cells, in the DRN. Rats received either an acute or chronic administration of buspirone or saline. Hereafter, the brains were processed for 5-HT, nNOS, and TH immunohistochemistry. We found that acute and chronic buspirone treatments significantly lowered the mean optical density of nNOS in the DRN as compared to controls. Meanwhile only the chronic buspirone treatment reduced the mean density of 5-HT and TH immunoreactivity but not the acute buspirone as compared to saline treated animals. Our findings suggest that buspirone treatment affects not only the intracellular content of 5-HT but also nNOS and TH. Therefore, the cellular effect of buspirone is more complex than thought.
Collapse
Affiliation(s)
- Ali Jahanshahi
- Department of Neuroscience, Maastricht University Medical Center, Maastricht, The Netherlands
| | | | | | | | | |
Collapse
|
29
|
Mitsukawa K, Lu X, Bartfai T. Galanin, galanin receptors, and drug targets. EXPERIENTIA SUPPLEMENTUM (2012) 2010; 102:7-23. [PMID: 21299058 DOI: 10.1007/978-3-0346-0228-0_2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Galanin, a neuropeptide widely expressed in the central and peripheral nervous systems and in the endocrine system, has been shown to regulate numerous physiological and pathological processes through interactions with three G-protein-coupled receptors, GalR1 through GalR3. Over the past decade, some of the receptor subtype-specific effects have been elucidated through pharmacological studies using subtype selective ligands, as well as through molecular approaches involving knockout animals. In this chapter, we summarize the current data which constitute the basis of targeting GalR1, GalR2, and GalR3 for the treatment of various human diseases and pathological conditions, including seizure, Alzheimer's disease, mood disorders, anxiety, alcohol intake in addiction, metabolic diseases, pain and solid tumors.
Collapse
Affiliation(s)
- K Mitsukawa
- Molecular and Integrative Neurosciences Department, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | | | | |
Collapse
|
30
|
Dendritic synthesis and release of the neuropeptide galanin: Morphological evidence from studies on rat locus coeruleus neurons. J Comp Neurol 2009; 516:199-212. [DOI: 10.1002/cne.22105] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
|
31
|
Nitric Oxide as an Initiator of Brain Lesions During the Development of Alzheimer Disease. Neurotox Res 2009; 16:293-305. [DOI: 10.1007/s12640-009-9066-5] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2009] [Revised: 05/16/2009] [Accepted: 05/16/2009] [Indexed: 01/11/2023]
|
32
|
Mitsukawa K, Lu X, Bartfai T. Bidirectional regulation of stress responses by galanin in mice: involvement of galanin receptor subtype 1. Neuroscience 2009; 160:837-46. [PMID: 19272414 DOI: 10.1016/j.neuroscience.2009.02.063] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2008] [Revised: 02/24/2009] [Accepted: 02/27/2009] [Indexed: 02/08/2023]
Abstract
The neuropeptide galanin has been shown to play a role in psychiatric disorders as well as in other biological processes including regulation of pain threshold through interactions with three G-protein coupled receptors, galanin receptor subtypes 1-3 (GalR1-3). While most of the pharmacological studies on galanin in stress-related disorders have been done with rats, the continuous development of genetically engineered mice involving galanin or its receptor subtype(s) validates the importance of mouse pharmacological studies. The present study on mice examined the homeostatic, endocrinological and neuroanatomical effects of the galanin, injected intracerebroventricularly (i.c.v.), in regulation of stress responses after restraint stress. Furthermore, the roles of GalR1 on these effects were studied using GalR1 knockout (KO) mice. The core body temperature and the locomotor activity were monitored with radio telemetry devices. Galanin (i.c.v.) decreased locomotor activity and exerted a bidirectional effect on the restraint stress-induced hyperthermia; a high dose of galanin significantly attenuated the stress-induced hyperthermic response, while a low dose of galanin moderately enhanced this response. The bidirectional effect of galanin was correlated with changes in stress hormone levels (adrenocorticotropic hormone and corticosterone). To neuroanatomically localize the effects of galanin on stress response, cFos immunoreactivity was assessed in galanin receptor rich areas; paraventricular nucleus (PVN) of the hypothalamus and the locus coeruleus (LC), respectively. A high dose of galanin significantly induced cFos activity in the LC but not in the PVN. In GalR1KO mice, a high dose of galanin failed to induce any of the above effects, suggesting the pivotal role of GalR1 in decreased locomotor activity and stress-resistant effects caused by galanin i.c.v. injection studied here.
Collapse
Affiliation(s)
- K Mitsukawa
- Molecular and Integrative Neurosciences Department, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | | | | |
Collapse
|
33
|
Tanaka M, Kido Y. Serotonergic regulation of galanin-induced selective macronutrient intake in self-selecting rats. THE JOURNAL OF MEDICAL INVESTIGATION 2009; 55:196-203. [PMID: 18797131 DOI: 10.2152/jmi.55.196] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
We investigated macronutrient intake after intraventricular injection of galanin (GAL, 3 nmol/5 microl/rat) and/or serotonin (5-HT, 50 nmol/5 microl/rat) in self-selecting fasted rats with preferences for either carbohydrates or fats. GAL injection significantly increased carbohydrate and total intake in all rats irrespective of macronutrient preference, whereas 5-HT alone did not affect macronutrient intake. The GAL-induced increase in total intake decreased to the level of saline controls when GAL was coinjected with 5-HT. The ratio of kilocalories of carbohydrates, fats and proteins (macronutrient energy ratio) after injections of GAL and/or 5-HT was similar to the saline control. In carbohydrate-preferring rats, GAL increased carbohydrate, protein and fat intake as well as total intake. Coinjection of GAL and 5-HT tended to decrease carbohydrate intake, but increase protein and fat intake. The macronutrient energy ratio after injection of GAL did not change, but the carbohydrate energy ratio decreased after 5-HT was injected, with or without GAL. In contrast, in fat-preferring rats, GAL significantly increased carbohydrate intake. Injection of 5-HT with or without GAL did not change total macronutrient intake. The macronutrient energy ratio did not change after GAL injection with or without 5-HT. These differences suggest that macronutrient preferences should be considered in any macronutrient intake study, and that serotonergic neurons play a part in the regulation of GAL-induced macronutrient intake.
Collapse
Affiliation(s)
- Michiko Tanaka
- Department of Food Sciences and Nutritional Health, Kyoto Prefectural University, Kyoto, Japan
| | | |
Collapse
|
34
|
Kuteeva E, Wardi T, Lundström L, Sollenberg U, Langel U, Hökfelt T, Ogren SO. Differential role of galanin receptors in the regulation of depression-like behavior and monoamine/stress-related genes at the cell body level. Neuropsychopharmacology 2008; 33:2573-85. [PMID: 18172432 DOI: 10.1038/sj.npp.1301660] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The present study on rat examined the role of galanin receptor subtypes in regulation of depression-like behavior as well as potential molecular mechanisms involved in the locus coeruleus (LC) and dorsal raphe (DR). The effect of intracerebroventricular (i.c.v.) infusion of galanin or galanin receptor GalR1- and GalR2-selective ligands was studied in the forced swim test, followed by quantitative in situ hybridization studies. Naive control, non-treated (swim control), saline- and fluoxetine-treated rats were used as controls in the behavioral and in situ hybridization studies. Subchronic treatment with fluoxetine reduced immobility and climbing time. Intracerebroventricular infusion of galanin, the GalR1 agonist M617 or the GalR2 antagonist M871 increased, while the GalR2(R3) agonist AR-M1896 decreased, immobility time compared to the aCSF-treated animals. Galanin also decreased the time of climbing. Galanin mRNA levels were upregulated by the combination of injection+swim stress in the saline- and the fluoxetine-treated groups in the LC, but not in the DR. Also tyrosine hydroxylase levels in the LC were increased following injection+swim stress in the saline- and fluoxetine-treated rats. Tryptophan hydroxylase 2 and serotonin transporter mRNAs were not significantly affected by any treatment. 5-HT(1A) mRNA levels were downregulated following i.c.v. galanin, M617 or AR-M1896 infusion. These results indicate a differential role of galanin receptor subtypes in depression-like behavior in rodents: GalR1 subtype may mediate 'prodepressive' and GalR2 'antidepressant' effects of galanin. Galanin has a role in behavioral adaptation to stressful events involving changes of molecules important for noradrenaline and/or serotonin transmission.
Collapse
Affiliation(s)
- Eugenia Kuteeva
- Department of Neuroscience, Karolinska Institutet, Retzius vag 8, Stockholm S-171 77 [corrected] Sweden.
| | | | | | | | | | | | | |
Collapse
|
35
|
Lu X, Ross B, Sanchez-Alavez M, Zorrilla EP, Bartfai T. Phenotypic analysis of GalR2 knockout mice in anxiety- and depression-related behavioral tests. Neuropeptides 2008; 42:387-97. [PMID: 18554714 PMCID: PMC3399724 DOI: 10.1016/j.npep.2008.04.009] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2007] [Revised: 03/20/2008] [Accepted: 04/21/2008] [Indexed: 11/18/2022]
Abstract
Neuropeptide galanin modulates a variety of central nervous system functions by signaling through three G-protein-coupled receptor subtypes, GalR1 through GalR3. Galanin and its receptors are expressed at high levels in the limbic structures of the rodent brain. Intracerebroventricular injection of galanin has been shown to modulate depression and anxiety-like behaviors in the rat. We have previously shown that chronic antidepressant treatments increase the binding of a GalR2-preferring ligand, galanin (2-11), to the dorsal raphe nucleus (DRN) of the rat, which, along with the finding that intra-DRN infusion of galanin (2-11) increases the release of serotonin in the hippocampus, suggests that GalR2 signaling might exert antidepressant-like actions by modulating ascending serotonergic outflow. Recently, two research groups reported their phenotypic analysis of a GalR2 knockout (GalR2KO) mouse line, produced by gene-trapping method and maintained on a 129S1/SvImJ genetic background. The only positive finding in that GalR2KO mouse line was an anxiogenic-like phenotype specific to the elevated plus-maze. Because it is known that genetic background can affect the outcome of behavioral tests, in the present study, we analyzed a separate GalR2KO line, which was produced by targeted deletion and maintained on a C57BL/6 background, using a different set of depression- and anxiety-related tests. GalR2KO mice exhibited a more persistent depressive-like phenotype in the learned helplessness paradigm as well as increased immobility in the tail suspension test when results from the present studies were combined by fixed effect meta-analysis with that reported by Gottsch and colleagues. GalR2KO mutants showed anxiety-like behavior comparable to wild-type littermates in the elevated plus-maze, open-field, and light-dark transfer tests. The present findings are consistent with a predicted antidepressant-like effect of GalR2 signaling, suggesting that GalR2 might be a valid drug target for depressive disorders.
Collapse
Affiliation(s)
- Xiaoying Lu
- The Harold L Dorris Neurological Institute, Department of Molecular and Integrative Neurosciences, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
| | | | | | | | | |
Collapse
|
36
|
de Vente J, Abildayeva K, van de Waarenburg M, Markerink-van Ittersum M, Steinbusch HWM, Mulder M. NO-mediated cGMP synthesis in cultured cholinergic neurons from the basal forebrain of the fetal rat. Brain Res 2008; 1217:25-36. [PMID: 18501878 DOI: 10.1016/j.brainres.2008.03.089] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2008] [Revised: 02/21/2008] [Accepted: 03/28/2008] [Indexed: 10/22/2022]
Abstract
Previously, using brain slices, we reported NO-mediated cGMP synthesis in all cholinergic fibers in the rat neocortex. In order to answer the question whether this property of cholinergic fibers was present before or developed after birth, we investigated properties of NO-responsiveness of cultured cholinergic forebrain neurons. Basal forebrain neurons of E16 fetal rat were cultured. Under the conditions chosen and after one day of culturing, all cells had attained a cholinergic phenotype using choline acetyltransferase or the vesicular acetylcholine transporter molecule as markers. Between 95-99% of the cells also expressed neuronal NOS. In the presence of 1 mM IBMX, a non-selective phosphodiesterase (PDE) inhibitor, 10 microM of the NO donor diethylamine-NONOate (DEANO) increased cGMP synthesis in 80% of the cells. cGMP levels in the cultured forebrain neurons were also increased when cells were stimulated with DEANO in the presence of the selective PDE inhibitors BAY 60-7550 (PDE2), sildenafil (PDE5), or the mixed type inhibitor papaverine (PDE2,5,10). Subpopulations of cells from the basal forebrain expressed mRNA for PDE2, PDE5, and PDE9. Atropine increased cGMP levels in an NO-dependent manner in a small population of cultured forebrain cells in the presence of IBMX. In conclusion, cultured cholinergic basal forebrain neurons present a heterogeneous cell population in the magnitude of their response to NO. NO-responsiveness of the cultured cholinergic neurons is already detectable after one day of culturing and indicates that NO-sensitivity of the cholinergic neurons of the rat basal forebrain is present well before birth.
Collapse
Affiliation(s)
- J de Vente
- Department of Psychiatry and Neuropsychology, European Graduate School of Neuroscience, Maastricht University, UNS50, POB 616, MD Maastricht, The Netherlands.
| | | | | | | | | | | |
Collapse
|
37
|
Abstract
Asthma has long been considered a condition in which psychological factors have a role. As in many illnesses, psychological variables may affect outcome in asthma via their effects on treatment adherence and symptom reporting. Emerging evidence suggests that the relation between asthma and psychological factors may be more complex than that, however. Central cognitive processes may influence not only the interpretation of asthma symptoms but also the manifestation of measurable changes in immune and physiologic markers of asthma. Furthermore, asthma and major depressive disorder share several risk factors and have similar patterns of dysregulation in key biologic systems, including the neuroendocrine stress response, cytokines, and neuropeptides. Despite the evidence that depression is common in people with asthma and exerts a negative impact on outcome, few treatment studies have examined whether improving symptoms of depression do, in fact, result in better control of asthma symptoms or improved quality of life in patients with asthma.
Collapse
Affiliation(s)
- Ryan J Van Lieshout
- Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, ON
| | | |
Collapse
|
38
|
Selective anterograde tracing of nonserotonergic projections from dorsal raphe nucleus to the basal forebrain and extended amygdala. J Chem Neuroanat 2008; 35:317-25. [PMID: 18434087 DOI: 10.1016/j.jchemneu.2008.02.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2007] [Revised: 02/28/2008] [Accepted: 02/29/2008] [Indexed: 11/20/2022]
Abstract
The dorsal raphe nucleus (DRN) contains both serotonergic and nonserotonergic projection neurons. Retrograde tracing studies have demonstrated that components of the basal forebrain and extended amygdala are targeted heavily by input from nonserotonergic DRN neurons. The object of this investigation was to examine the terminal distribution of nonserotonergic DRN projections in the basal forebrain and extended amygdala, using a technique that allows selective anterograde tracing of nonserotonergic DRN projections. To trace nonserotonergic DRN projections, animals were pretreated with nomifensine, desipramine and the serotonergic neurotoxin 5,7-dihydroxytryptamine (5,7-DHT), 7 days prior to placing an iontophoretic injection of biotinylated dextran amine (BDA) into the DRN. In animals treated with 5,7-DHT, numerous nonserotonergic BDA-labeled fibers ascended to the basal forebrain in the medial forebrain bundle system. Some of these labeled fibers crossed through the lateral hypothalamus, bed nucleus of the stria terminalis, and substantial innominata. These fibers entered the amygdala through the ansa peduncularis and ramified within the central and basolateral amygdaloid nuclei. Other fibers entered the diagonal band of Broca and formed a dense plexus of labeled fibers in the dorsal half of the intermediate portion of the lateral septal nucleus and the septohippocampal nucleus. These findings demonstrate that the basal forebrain and extended amygdala receive a dense projection from nonserotonergic DRN neurons. Given that the basal forebrain plays a critical role in processes such as motivation, affect, and behavioral control, these findings support the hypothesis that nonserotonergic DRN projections may exert substantial modulatory control over emotional and motivational functions.
Collapse
|
39
|
Rajarao SJR, Platt B, Sukoff SJ, Lin Q, Bender CN, Nieuwenhuijsen BW, Ring RH, Schechter LE, Rosenzweig-Lipson S, Beyer CE. Anxiolytic-like activity of the non-selective galanin receptor agonist, galnon. Neuropeptides 2007; 41:307-20. [PMID: 17637475 DOI: 10.1016/j.npep.2007.05.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2007] [Revised: 05/09/2007] [Accepted: 05/10/2007] [Indexed: 01/22/2023]
Abstract
Galanin's influence on monoaminergic neurotransmission, together with its discrete CNS distribution in corticolimbic brain areas, points to a potential role for this neuropeptide in mediating anxiety- and depression-like responses. To evaluate this hypothesis, the non-selective galanin receptor agonist, galnon, was tested in multiple preclinical models of anxiolytic- and antidepressive-like activity. Acute administration of galnon (0.03-1mg/kg, i.p.) dose-dependently increased punished crossings in the four plate test, with magnitude similar to the effects of the endogenous ligand, galanin (0.1-1.0 microg, i.c.v.). Moreover, the effects of galnon and galanin were blocked by central administration of the non-selective galanin receptor antagonist, M35 (10 microg, i.c.v.). Interestingly, the benzodiazepine receptor antagonist, flumazenil (1mg/kg, i.p.), reversed galnon's effect in the four plate test, implicating GABAergic neurotransmission as a potential mechanism underlying this anxiolytic-like response. In the elevated zero maze, galnon (0.3-3.0mg/kg, i.p.) and galanin (0.03-0.3 microg, i.c.v.) increased the time spent in the open arms, while in the stress-induced hyperthermia model, galnon (0.3-30 mg/kg, i.p.) attenuated stress-induced changes in body temperature. Consistent with these anxiolytic-like effects, in vivo microdialysis showed that acute galnon (3mg/kg, i.p.) treatment preferentially elevated levels of GABA in the rat amygdala, a brain area linked to fear and anxiety behaviors. In contrast to the effects in anxiety models, neither galnon (1-5.6 mg/kg, i.p.) nor galanin (0.3-3.0 microg, i.c.v.) demonstrated antidepressant-like effects in the mouse tail suspension test. Galnon (1-10mg/kg, i.p.) also failed to reduce immobility time in the rat forced swim test. In vitro, galnon and galanin showed affinity for human galanin receptors expressed in Bowes melanoma cells (K(i)=5.5 microM and 0.2 nM, respectively). Galanin displayed high affinity and functional potency for membranes expressing rat GALR1 receptors (K(i)=0.85 nM; EC(50)=0.6 nM), while galnon (10 microM) failed to displace radiolabeled galanin or inhibit cAMP production in the same GALR1 cell line. Galnon (10 microM) showed affinity for NPY1, NK2, M5, and somatostatin receptors but no affinity for galanin receptors expressed in rat hippocampal membranes. Taken together, the present series of studies demonstrate novel effects of galnon in various preclinical models of anxiety and highlight the galaninergic system as a novel therapeutic target for the treatment of anxiety-related disorders. Moreover, these data indicate rodent GALR1 receptors do not mediate galnon's in vivo activity.
Collapse
Affiliation(s)
- S Johannes R Rajarao
- Depression and Anxiety Research, Discovery Neuroscience, Wyeth Research, CN8000, Princeton, NJ 08543, USA.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
40
|
Clark MS, McDevitt RA, Neumaier JF. Quantitative mapping of tryptophan hydroxylase-2, 5-HT1A, 5-HT1B, and serotonin transporter expression across the anteroposterior axis of the rat dorsal and median raphe nuclei. J Comp Neurol 2006; 498:611-23. [PMID: 16917826 DOI: 10.1002/cne.21073] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Depression and anxiety disorders are among the leading causes of morbidity, mortality, and disability in the United States. Impaired serotonin neurotransmission appears to be a central mechanism inducing depressive and anxiety symptoms. Most serotonergic innervation of the forebrain arises from the median raphe nucleus (MRN) and dorsal raphe nucleus (DRN). The DRN displays a complex internal morphology, with distinct subregions varying across the anteroposterior (A-P) axis. However, many studies have considered the DRN as a whole or used easily confused terminology to describe position. Given the large differences in receptor expression, electrophysiological properties, and connectivity between various subregions of the DRN, it appears probable that they have distinct functional roles in the regulation of behavior. To foster uniform definitions of locations within these nuclei, we have quantitatively mapped gene expression in DRN and MRN for tryptophan hydroxylase-2 (Tph2), the serotonin transporter, as well as 5-HT1A and 5-HT1B receptors. These quantitative studies revealed differences in the density of expression of each gene in the ventromedial, dorsomedial, and dorsolateral subnuclei of the DRN, as well as distinct variation in expression across the A-P axis. These findings provide additional evidence that subregions of the DRN are heterogeneous and need to be considered independently. In addition, a fine scale map of Tph2 expression suggests definitions for categorical divisions of the DRN across the A-P axis. These are based on distinct morphological patterns of Tph2 expression and may be more reflective of physiology than the classic terminology dividing the DRN into equal thirds.
Collapse
Affiliation(s)
- Michael S Clark
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, Washington 98195, USA
| | | | | |
Collapse
|
41
|
Ogren SO, Kuteeva E, Hökfelt T, Kehr J. Galanin receptor antagonists : a potential novel pharmacological treatment for mood disorders. CNS Drugs 2006; 20:633-54. [PMID: 16863269 DOI: 10.2165/00023210-200620080-00003] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The pathophysiology of mood disorders involves several genetic and social predisposing factors, as well as a dysregulated response to chronic stress. Accumulated evidence during the last two decades has implicated disturbances in brain serotonin and/or noradrenaline (norepinephrine) neurotransmission in the aetiology of depression. In fact, current pharmacological treatment for mood disorders is based on the use of drugs that act mainly by enhancing brain serotonin and noradrenaline neurotransmission by blockade of the active reuptake mechanism for these neurotransmitters. However, current antidepressant drugs have a delayed onset of therapeutic action, and a substantial number of patients do not respond adequately to them. In addition, these drugs have a number of adverse effects that limit patient compliance. In view of this, there is an intense search to identify novel (receptor) targets for antidepressant therapy. Recent studies have indicated that several neuropeptides and their receptors are potential candidates for the development of novel antidepressant treatment. In this context, galanin is of particular interest, since it is co-localised with serotonin in the dorsal raphe nucleus and with noradrenaline in the locus coeruleus, nuclei known to play a major role in affective disorders and in the action of antidepressant drugs. The actions of galanin are mediated by three receptor subtypes (GAL1, GAL2 and GAL3), which are coupled to different intracellular effector systems. Studies in rats have shown that galanin administered intracerebroventricularly is a potent inhibitor of mesencephalic serotonergic neurotransmission, as indicated by a long-lasting reduction in the release of serotonin in the hippocampus. This inhibitory effect is related to activation of the galanin receptors located on the dorsal raphe neurons. Moreover, intracerebroventricular galanin alters the gene expression of serotonin 5-HT1A autoreceptors in the dorsal raphe and also changes their functional activity. In addition, galanin produces a functional blockade of postsynaptic 5-HT1A receptor-mediated responses. Both pharmacological and genetic studies suggest a role for galanin in depression-like behaviour in rodent models. Transgenic mice overexpressing galanin under the control of the platelet-derived growth factor-beta promoter display increased immobility in the forced swim test. Intracerebroventricular administration of galanin in the rat increases depression-like behaviour, and this is fully blocked by the nonselective peptide galanin receptor antagonist M35. Importantly, M35 alone administered intracerebroventricularly produces an antidepressant-like effect. Recently, newly developed receptor-specific nonpeptidergic galanin GAL3 receptor antagonists (SNAP-37889 and SNAP-398299), which cross the blood-brain barrier after systemic administration, have shown antidepressant-like activity in several animal models. On the other hand, stimulation of the GAL2 receptor at the raphe level by local application of the GAL2 receptor agonist galanin (2-11) has been shown to increase serotonin levels in the hippocampus and dorsal raphe. These results indicate an important (mainly inhibitory) role of galanin as a regulator of brain serotonin and 5-HT1A receptor-mediated transmission, which may be of potential importance for understanding mood disorders and for the development of antidepressant drugs. Taken together, the present evidence suggests that antidepressant efficacy may be associated with compounds acting as antagonists at the GAL3 and/or possibly GAL1 receptors, and/or agonists at the GAL2 receptor.
Collapse
Affiliation(s)
- Sven Ove Ogren
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.
| | | | | | | |
Collapse
|
42
|
Okere CO, Waterhouse BD. Acute restraint increases NADPH-diaphorase staining in distinct subregions of the rat dorsal raphe nucleus: implications for raphe serotonergic and nitrergic transmission. Brain Res 2006; 1119:174-81. [PMID: 16989783 DOI: 10.1016/j.brainres.2006.08.058] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2006] [Revised: 07/18/2006] [Accepted: 08/11/2006] [Indexed: 11/21/2022]
Abstract
The brainstem dorsal raphe nucleus (DRN) maintains a rough topographic cell ordering with respect to biological function. This study examined the influence of acute restraint on nitric oxide (NO) synthase (NOS) neurons in distinct DRN subregions. NADPH diaphorase staining (NOS index) intensity was higher in the DRN dorsomedial, ventromedial and lateral wings subregions of restrained vs. control rats. The mean number of cells was not significantly different between both groups of animals. The restrained-induced NADPH-diaphorase activity was significantly higher in the rostral ventromedial and caudal lateral wings than the corresponding caudal and rostral subregions but no significant difference was observed between rostral and caudal dorsomedial subregions. These observations suggest that restraint stress differentially activates NO-producing neurons in distinct DRN subregions.
Collapse
Affiliation(s)
- Chuma O Okere
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA 19129, USA.
| | | |
Collapse
|
43
|
Salio C, Lossi L, Ferrini F, Merighi A. Neuropeptides as synaptic transmitters. Cell Tissue Res 2006; 326:583-98. [PMID: 16847638 DOI: 10.1007/s00441-006-0268-3] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2006] [Accepted: 05/31/2006] [Indexed: 12/20/2022]
Abstract
Neuropeptides are small protein molecules (composed of 3-100 amino-acid residues) that have been localized to discrete cell populations of central and peripheral neurons. In most instances, they coexist with low-molecular-weight neurotransmitters within the same neurons. At the subcellular level, neuropeptides are selectively stored, singularly or more frequently in combinations, within large granular vesicles. Release occurs through mechanisms different from classical calcium-dependent exocytosis at the synaptic cleft, and thus they account for slow synaptic and/or non-synaptic communication in neurons. Neuropeptide co-storage and coexistence can be observed throughout the central nervous system and are responsible for a series of functional interactions that occur at both pre- and post-synaptic levels. Thus, the subcellular site(s) of storage and sorting mechanisms into different neuronal compartments are crucial to the mode of release and the function of neuropeptides as neuronal messengers.
Collapse
Affiliation(s)
- Chiara Salio
- Dipartimento di Morfofisiologia Veterinaria and Rita Levi Montalcini Center for Brain Repair, Via Leonardo da Vinci 44, 10095, Grugliasco (TO), Italy
| | | | | | | |
Collapse
|
44
|
Okere CO, Waterhouse BD. Activity-dependent heterogeneous populations of nitric oxide synthase neurons in the rat dorsal raphe nucleus. Brain Res 2006; 1086:117-32. [PMID: 16616732 DOI: 10.1016/j.brainres.2006.02.107] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2006] [Revised: 02/17/2006] [Accepted: 02/20/2006] [Indexed: 11/18/2022]
Abstract
The brainstem dorsal raphe nucleus (DRN) contains an abundant distribution of nitric oxide (NO) synthase (NOS)-containing neuronal profiles in two distinct populations: faint- and intense-immunoreactive cells in midline (ventromedial and dorsomedial) and lateral wing subregions, respectively. This study tested the hypothesis that different functional dynamics underlie the topography of NOS-containing cells in the DRN rostrocaudal and mediolateral neuraxis by using a capsaicin challenge paradigm (50 mg/kg, subcutaneous). Compared with vehicle, capsaicin significantly and preferentially increased nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d, an index of constitutive NOS) reactivity in the rostral midline and caudal lateral wing subregions. Furthermore, capsaicin activated more Fos-positive cells than vehicle within all subregions of the DRN but with a caudal versus rostral predominance in activation pattern. In addition, a high proportion of capsaicin-induced Fos cells in the midline but almost none in lateral wing stained for NADPH-d. These observations suggest the existence of two functionally distinct populations of NOS neurons in the DRN. Furthermore, capsaicin increased galanin immunoreactivity with predominant staining in cell soma and fiber processes in midline and lateral wing subregions of the nucleus, respectively. The total capsaicin-induced galanin immunoreactivity was higher in rostral versus caudal DRN, and a high proportion of galanin-positive cells in the midline also contained NADPH-d and neuronal NOS, thus suggesting a potential NO-galanin interaction in these neurons. The differential pattern of Fos/NADPH-d colocalization across the nucleus suggests that midline and lateral wing NOS neurons of the DRN express their neuromodulatory actions on discrete efferent targets via different intracellular mechanisms.
Collapse
Affiliation(s)
- Chuma O Okere
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, 2900 W Queen Lane, Philadelphia, PA 19129, USA.
| | | |
Collapse
|
45
|
Lee HS, Park SH, Song WC, Waterhouse BD. Retrograde study of hypocretin-1 (orexin-A) projections to subdivisions of the dorsal raphe nucleus in the rat. Brain Res 2005; 1059:35-45. [PMID: 16153616 DOI: 10.1016/j.brainres.2005.08.016] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2005] [Revised: 08/05/2005] [Accepted: 08/07/2005] [Indexed: 10/25/2022]
Abstract
A retrograde tracer, WGA-apo-HRP-gold (WG), was injected into each subdivision of the dorsal raphe (DR) nucleus, and subsequent orexin-A immunostaining was performed for the tuberal region of the hypothalamus in order to investigate orexin projections to the DR. Similar to previous studies, the majority of orexin-single-labeled neurons were observed at the dorsal half of the lateral hypothalamus (LH), the circle around the fornix, i.e., perifornical nucleus (PeF), and the area dorsal to the fornix. The present study reports that hypothalamic neurons exhibited differential projections to each subdivision of the DR. Following WG injections into rostral DR, WG-single-labeled cells were observed at the dorsal half of the LH as well as dorsomedial hypothalamic nucleus. The major input to the intermediate DR originates from the ventromedial portion of the LH, PeF, and the area dorsal to the PeF, whereas one to lateral wing DR derived from PeF as well as the ventrolateral portion of the LH. Following WG injections into caudal DR, WG-single-labeled cells were located at ventromedial LH and the ventrolateral portion of the posterior hypothalamus. Following WG injections into each DR subdivision, WG/orexin-double-labeled neurons were observed at LH, PeF, and the area dorsal to the PeF. Only a few double-labeled cells were observed in dorsomedial and posterior hypothalamic nuclei. Our observations suggest that various hypothalamic neurons differentially project to each subdivision of the DR, a portion of which is orexin-immunoreactive. These orexin-immunoreactive DR-projecting hypothalamic neurons might have wake-related influences over a variety of brain functions subject to DR efferent regulation, including affective behavior, autonomic control, nociception, cognition, and sensorimotor integration.
Collapse
Affiliation(s)
- Hyun S Lee
- Department of Anatomy, College of Medicine, Konkuk University, Chungju, Chungbuk 380-701, South Korea.
| | | | | | | |
Collapse
|
46
|
Zheng K, Kuteeva E, Xia S, Bartfai T, Hökfelt T, Xu ZQD. Age-related impairments of synaptic plasticity in the lateral perforant path input to the dentate gyrus of galanin overexpressing mice. Neuropeptides 2005; 39:259-67. [PMID: 15944020 DOI: 10.1016/j.npep.2005.02.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2005] [Accepted: 02/15/2005] [Indexed: 11/17/2022]
Abstract
In the present study, electrophysiological recordings were made from hippocampal slices obtained from mice overexpressing galanin under the promoter for the platelet-derived growth factor-B (GalOE mice). In these mice, a particularly strong galanin expression is seen in the granule cell layer/mossy fibers. Paired-pulse facilitation (PPF) of excitatory postsynaptic field potentials (fEPSPs) at the lateral perforant path (LPP)-dentate gyrus synapses was elicited in the dentate gyrus after stimulation with different interpulse intervals. Slices from young adult wild-type (WT) animals showed significant PPF of the 2nd EPSP evoked with paired-pulse stimuli, while PPF was reduced in slices from young adult GalOE mice, as well as aged WT mice, but were not observed at all in slices from aged GalOE animals. Application of the putative galanin antagonist M35 increased PPF in slices from aged WT mice as well as from adult and aged GalOE mice, but had no effect in slices taken from young adult WT mice. These data indicate that galanin is involved in hippocampal synaptic plasticity, in particular in age-related reduction of synaptic plasticity in the LPP input to the dentate gyrus. Galaninergic mechanisms may therefore represent therapeutic targets for treatment of age-related memory deficits and Alzheimer's disease.
Collapse
Affiliation(s)
- Kang Zheng
- Department of Neuroscience, Karolinska Institutet, S-171 71, Stockholm, Sweden
| | | | | | | | | | | |
Collapse
|
47
|
Xu ZQD, Zheng K, Hökfelt T. Electrophysiological studies on galanin effects in brain--progress during the last six years. Neuropeptides 2005; 39:269-75. [PMID: 15944021 DOI: 10.1016/j.npep.2005.02.003] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2005] [Accepted: 02/03/2005] [Indexed: 11/27/2022]
Abstract
The effects of galanin and galanin fragments have been studied on neurons in various brain regions of rodents using electrophysiological techniques. Here, we mainly review reports published during the last six years, that is after the second galanin symposium in 1998. These papers deal with locus coeruleus (LC), the hippocampal formation (HF), hypothalamus, the nucleus of the diagonal band of Broca (DBB) and the dorsal vagal complex (DVC). In most cases galanin has an inhibitory effect by increasing a potassium conductance or reducing a calcium conductance. In LC, beside a direct inhibitory effect, galanin exerts an indirect effect enhancing the noradrenaline-induced hyperpolarization. In the HF, galanin (1-15), but not galanin (1-29), induces hyperpolarization in CA3 pyramidal neurons. Inhibitory effects of galanin on several forms of synaptic plasticity including long-term potentiation, frequency facilitation and paired-pulse facilitation have also been demonstrated in normal and transgenic animals. In the hypothalamic arcuate nucleus galanin has a presynaptic action inhibiting glutamate release, as well as a postsynaptic effect via the galanin R1 receptor. In the DVC, galanin inhibits dorsal vagal motor neurons projecting to the stomach by activation of a postsynaptic galanin receptor. However, excitatory effects of galanin have also been reported in several regions, such as the DBB nucleus, where galanin increases excitability by decreasing a K+ conductance. Taken together, electrophysiological studies have further supported the role of galanin as a neurotransmitter/neuromodulator in the brain.
Collapse
Affiliation(s)
- Zhi-Qing David Xu
- Department of Neuroscience, Karolinska Institutet, S-171 71, Stockholm, Sweden.
| | | | | |
Collapse
|
48
|
Kim MA, Lee HS, Lee BY, Waterhouse BD. Reciprocal connections between subdivisions of the dorsal raphe and the nuclear core of the locus coeruleus in the rat. Brain Res 2005; 1026:56-67. [PMID: 15476697 DOI: 10.1016/j.brainres.2004.08.022] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/10/2004] [Indexed: 11/18/2022]
Abstract
The interconnection between two brainstem monoaminergic nuclei, the dorsal raphe (DR) and the locus coeruleus (LC), was analyzed in the rat using retrograde tracing and immunocytochemistry. Gold-conjugated and inactivated wheatgerm agglutinin-horseradish peroxidase (WGA-apo-HRP-gold) was injected into subdivisions of the DR or rostro-caudal levels of the nuclear core of the LC, and labeled LC or DR neurons were identified by dopamine-beta-hydroxylase (DBH) or 5-hydroxytryptamine (5-HT) immunostaining, respectively. Within the LC-DR projection, the caudal principal LC projected to the caudal, ventromedial, and interfascicular DR. Mid-LC as well as caudal LC projected with an ipsilateral predominance to the lateral wing subdivision of the DR. A few rostral LC neurons projected to caudal, dorsomedial, and ventromedial DR. Within the DR-LC projection, the rostral LC received inputs mainly from the caudal, dorsomedial, and ventromedial DR. Mid-LC to caudal LC received projections from mid-DR to caudal DR, with the heaviest projection from the ipsilateral lateral wing as well as caudal DR. The DR-LC projection was substantially more robust than LC-DR and included both serotonergic and nonserotonergic components. Thus, the data demonstrate topographically ordered, reciprocal connectivity between DR and LC with particularly strong projections from DR to LC. Communication between these two brainstem monoaminergic nuclei may be critical for a variety of functions including sleep-wake regulation, vigilance, analgesia, cognition, and stress responses.
Collapse
Affiliation(s)
- Myung-A Kim
- Department of Premedical Science, College of Medicine, Konkuk University, Chungju, Chungbuk 380-701, South Korea
| | | | | | | |
Collapse
|
49
|
De Silva DJ, French SJ, Cheung NY, Swinson AK, Bendotti C, Rattray M. Rat brain serotonin neurones that express neuronal nitric oxide synthase have increased sensitivity to the substituted amphetamine serotonin toxins 3,4-methylenedioxymethamphetamine and p-chloroamphetamine. Neuroscience 2005; 134:1363-75. [PMID: 16054768 DOI: 10.1016/j.neuroscience.2005.05.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2004] [Revised: 03/11/2005] [Accepted: 05/11/2005] [Indexed: 11/27/2022]
Abstract
Substituted amphetamines such as p-chloroamphetamine and the abused drug methylenedioxymethamphetamine cause selective destruction of serotonin axons in rats, by unknown mechanisms. Since some serotonin neurones also express neuronal nitric oxide synthase, which has been implicated in neurotoxicity, the present study was undertaken to determine whether nitric oxide synthase expressing serotonin neurones are selectively vulnerable to methylenedioxymethamphetamine or p-chloroamphetamine. Using double-labeling immunocytochemistry and double in situ hybridization for nitric oxide synthase and the serotonin transporter, it was confirmed that about two thirds of serotonergic cell bodies in the dorsal raphé nucleus expressed nitric oxide synthase, however few if any serotonin transporter immunoreactive axons in striatum expressed nitric oxide synthase at detectable levels. Methylenedioxymethamphetamine (30 mg/kg) or p-chloroamphetamine (2 x 10 mg/kg) was administered to Sprague-Dawley rats, and 7 days after drug administration there were modest decreases in the levels of serotonin transporter protein in frontal cortex, and striatum using Western blotting, even though axonal loss could be clearly seen by immunostaining. p-Chloroamphetamine or methylenedioxymethamphetamine administration did not alter the level of nitric oxide synthase in striatum or frontal cortex, determined by Western blotting. Analysis of serotonin neuronal cell bodies 7 days after p-chloroamphetamine treatment, revealed a net down-regulation of serotonin transporter mRNA levels, and a profound change in expression of nitric oxide synthase, with 33% of serotonin transporter mRNA positive cells containing nitric oxide synthase mRNA, compared with 65% in control animals. Altogether these results support the hypothesis that serotonin neurones which express nitric oxide synthase are most vulnerable to substituted amphetamine toxicity, supporting the concept that the selective vulnerability of serotonin neurones has a molecular basis.
Collapse
Affiliation(s)
- D J De Silva
- Wolfson Centre for Age-Related Diseases, School of Biomedical Sciences, King's College London, Guy's Hospital Campus, UK
| | | | | | | | | | | |
Collapse
|
50
|
Lu X, Barr AM, Bartfai T. Galanin receptors as novel drug targets for the treatment of depression and anxiety. Drug Dev Res 2005. [DOI: 10.1002/ddr.20026] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
|