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Higa GSV, Viana FJC, Francis-Oliveira J, Cruvinel E, Franchin TS, Marcourakis T, Ulrich H, De Pasquale R. Serotonergic neuromodulation of synaptic plasticity. Neuropharmacology 2024; 257:110036. [PMID: 38876308 DOI: 10.1016/j.neuropharm.2024.110036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2024] [Revised: 05/15/2024] [Accepted: 06/11/2024] [Indexed: 06/16/2024]
Abstract
Synaptic plasticity constitutes a fundamental process in the reorganization of neural networks that underlie memory, cognition, emotional responses, and behavioral planning. At the core of this phenomenon lie Hebbian mechanisms, wherein frequent synaptic stimulation induces long-term potentiation (LTP), while less activation leads to long-term depression (LTD). The synaptic reorganization of neuronal networks is regulated by serotonin (5-HT), a neuromodulator capable of modify synaptic plasticity to appropriately respond to mental and behavioral states, such as alertness, attention, concentration, motivation, and mood. Lately, understanding the serotonergic Neuromodulation of synaptic plasticity has become imperative for unraveling its impact on cognitive, emotional, and behavioral functions. Through a comparative analysis across three main forebrain structures-the hippocampus, amygdala, and prefrontal cortex, this review discusses the actions of 5-HT on synaptic plasticity, offering insights into its role as a neuromodulator involved in emotional and cognitive functions. By distinguishing between plastic and metaplastic effects, we provide a comprehensive overview about the mechanisms of 5-HT neuromodulation of synaptic plasticity and associated functions across different brain regions.
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Affiliation(s)
- Guilherme Shigueto Vilar Higa
- Laboratório de Neurofisiologia, Departamento de Fisiologia e Biofísica, Universidade de São Paulo, Butantã, São Paulo, SP, 05508-000, Brazil; Departamento de Bioquímica, Instituto de Química (USP), Butantã, São Paulo, SP, 05508-900, Brazil
| | - Felipe José Costa Viana
- Laboratório de Neurofisiologia, Departamento de Fisiologia e Biofísica, Universidade de São Paulo, Butantã, São Paulo, SP, 05508-000, Brazil
| | - José Francis-Oliveira
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, AL, 35233, USA
| | - Emily Cruvinel
- Laboratório de Neurofisiologia, Departamento de Fisiologia e Biofísica, Universidade de São Paulo, Butantã, São Paulo, SP, 05508-000, Brazil
| | - Thainá Soares Franchin
- Laboratório de Neurofisiologia, Departamento de Fisiologia e Biofísica, Universidade de São Paulo, Butantã, São Paulo, SP, 05508-000, Brazil
| | - Tania Marcourakis
- Departamento de Análises Clínicas e Toxicológicas, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, Butantã, São Paulo, SP, 05508-000, Brazil
| | - Henning Ulrich
- Departamento de Bioquímica, Instituto de Química (USP), Butantã, São Paulo, SP, 05508-900, Brazil
| | - Roberto De Pasquale
- Laboratório de Neurofisiologia, Departamento de Fisiologia e Biofísica, Universidade de São Paulo, Butantã, São Paulo, SP, 05508-000, Brazil.
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Francis-Oliveira J, Higa GSV, Viana FJC, Cruvinel E, Carlos-Lima E, da Silva Borges F, Zampieri TT, Rebello FP, Ulrich H, De Pasquale R. TREK-1 inhibition promotes synaptic plasticity in the prelimbic cortex. Exp Neurol 2024; 373:114652. [PMID: 38103709 DOI: 10.1016/j.expneurol.2023.114652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 11/28/2023] [Accepted: 12/10/2023] [Indexed: 12/19/2023]
Abstract
Synaptic plasticity is one of the putative mechanisms involved in the maturation of the prefrontal cortex (PFC) during postnatal development. Early life stress (ELS) affects the shaping of cortical circuitries through impairment of synaptic plasticity supporting the onset of mood disorders. Growing evidence suggests that dysfunctional postnatal maturation of the prelimbic division (PL) of the PFC might be related to the emergence of depression. The potassium channel TREK-1 has attracted particular interest among many factors that modulate plasticity, concerning synaptic modifications that could underlie mood disorders. Studies have found that ablation of TREK-1 increases the resilience to depression, while rats exposed to ELS exhibit higher TREK-1 levels in the PL. TREK-1 is regulated by multiple intracellular transduction pathways including the ones activated by metabotropic receptors. In the hippocampal neurons, TREK-1 interacts with the serotonergic system, one of the main factors involved in the action of antidepressants. To investigate possible mechanisms related to the antidepressant role of TREK-1, we used brain slice electrophysiology to evaluate the effects of TREK-1 pharmacological blockade on synaptic plasticity at PL circuitry. We extended this investigation to animals subjected to ELS. Our findings suggest that in non-stressed animals, TREK-1 activity is required for the reduction of synaptic responses mediated by the 5HT1A receptor activation. Furthermore, we demonstrate that TREK-1 blockade promotes activity-dependent long-term depression (LTD) when acting in synergy with 5HT1A receptor stimulation. On the other hand, in ELS animals, TREK-1 blockade reduces synaptic transmission and facilitates LTD expression. These results indicate that TREK-1 inhibition stimulates synaptic plasticity in the PL and this effect is more pronounced in animals subjected to ELS during postnatal development.
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Affiliation(s)
- José Francis-Oliveira
- Laboratório de Neurofisiologia, Departamento de Fisiologia e Biofísica, Universidade de São Paulo, Butantã, SP 05508-000, Brazil; Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, AL 35233, USA
| | - Guilherme Shigueto Vilar Higa
- Laboratório de Neurofisiologia, Departamento de Fisiologia e Biofísica, Universidade de São Paulo, Butantã, SP 05508-000, Brazil; Departamento de Bioquímica, Instituto de Química (USP), Butantã, SP 05508-900, Brazil; Laboratório de Neurogenética, Universidade Federal do ABC, São Bernardo do Campo, SP 09210-580, Brazil
| | - Felipe José Costa Viana
- Laboratório de Neurofisiologia, Departamento de Fisiologia e Biofísica, Universidade de São Paulo, Butantã, SP 05508-000, Brazil
| | - Emily Cruvinel
- Laboratório de Neurofisiologia, Departamento de Fisiologia e Biofísica, Universidade de São Paulo, Butantã, SP 05508-000, Brazil
| | - Estevão Carlos-Lima
- Laboratório de Neurofisiologia, Departamento de Fisiologia e Biofísica, Universidade de São Paulo, Butantã, SP 05508-000, Brazil
| | - Fernando da Silva Borges
- Department of Physiology & Pharmacology, SUNY Downstate Health Sciences University, Brooklyn, NY 11203, USA
| | - Thais Tessari Zampieri
- Laboratório de Neurofisiologia, Departamento de Fisiologia e Biofísica, Universidade de São Paulo, Butantã, SP 05508-000, Brazil
| | - Fernanda Pereira Rebello
- Laboratório de Neurofisiologia, Departamento de Fisiologia e Biofísica, Universidade de São Paulo, Butantã, SP 05508-000, Brazil
| | - Henning Ulrich
- Departamento de Bioquímica, Instituto de Química (USP), Butantã, SP 05508-900, Brazil
| | - Roberto De Pasquale
- Laboratório de Neurofisiologia, Departamento de Fisiologia e Biofísica, Universidade de São Paulo, Butantã, SP 05508-000, Brazil.
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3
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Ogelman R, Gomez Wulschner LE, Hoelscher VM, Hwang IW, Chang VN, Oh WC. Serotonin modulates excitatory synapse maturation in the developing prefrontal cortex. Nat Commun 2024; 15:1368. [PMID: 38365905 PMCID: PMC10873381 DOI: 10.1038/s41467-024-45734-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Accepted: 02/02/2024] [Indexed: 02/18/2024] Open
Abstract
Serotonin (5-HT) imbalances in the developing prefrontal cortex (PFC) are linked to long-term behavioral deficits. However, the synaptic mechanisms underlying 5-HT-mediated PFC development are unknown. We found that chemogenetic suppression and enhancement of 5-HT release in the PFC during the first two postnatal weeks decreased and increased the density and strength of excitatory spine synapses, respectively, on prefrontal layer 2/3 pyramidal neurons in mice. 5-HT release on single spines induced structural and functional long-term potentiation (LTP), requiring both 5-HT2A and 5-HT7 receptor signals, in a glutamatergic activity-independent manner. Notably, LTP-inducing 5-HT stimuli increased the long-term survival of newly formed spines ( ≥ 6 h) via 5-HT7 Gαs activation. Chronic treatment of mice with fluoxetine, a selective serotonin-reuptake inhibitor, during the first two weeks, but not the third week of postnatal development, increased the density and strength of excitatory synapses. The effect of fluoxetine on PFC synaptic alterations in vivo was abolished by 5-HT2A and 5-HT7 receptor antagonists. Our data describe a molecular basis of 5-HT-dependent excitatory synaptic plasticity at the level of single spines in the PFC during early postnatal development.
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Affiliation(s)
- Roberto Ogelman
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO, 80045, USA
| | - Luis E Gomez Wulschner
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO, 80045, USA
| | - Victoria M Hoelscher
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO, 80045, USA
| | - In-Wook Hwang
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO, 80045, USA
| | - Victoria N Chang
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO, 80045, USA
| | - Won Chan Oh
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO, 80045, USA.
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Mitroshina EV, Marasanova EA, Vedunova MV. Functional Dimerization of Serotonin Receptors: Role in Health and Depressive Disorders. Int J Mol Sci 2023; 24:16416. [PMID: 38003611 PMCID: PMC10671093 DOI: 10.3390/ijms242216416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 11/11/2023] [Accepted: 11/13/2023] [Indexed: 11/26/2023] Open
Abstract
Understanding the neurobiological underpinnings of depressive disorder constitutes a pressing challenge in the fields of psychiatry and neurobiology. Depression represents one of the most prevalent forms of mental and behavioral disorders globally. Alterations in dimerization capacity can influence the functional characteristics of serotonin receptors and may constitute a contributing factor to the onset of depressive disorders. The objective of this review is to consolidate the current understanding of interactions within the 5-HT receptor family and between 5-HT receptors and members of other receptor families. Furthermore, it aims to elucidate the role of such complexes in depressive disorders and delineate the mechanisms through which antidepressants exert their effects.
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Affiliation(s)
- Elena V. Mitroshina
- Institute of Biology and Biomedicine, Lobachevsky State University of Nizhny Novgorod, 23 Gagarin Avenue, 603022 Nizhny Novgorod, Russia; (E.A.M.)
| | - Ekaterina A. Marasanova
- Institute of Biology and Biomedicine, Lobachevsky State University of Nizhny Novgorod, 23 Gagarin Avenue, 603022 Nizhny Novgorod, Russia; (E.A.M.)
| | - Maria V. Vedunova
- Institute of Biology and Biomedicine, Lobachevsky State University of Nizhny Novgorod, 23 Gagarin Avenue, 603022 Nizhny Novgorod, Russia; (E.A.M.)
- Faculty of Biology and Biotechnology, HSE University, St. Profsoyuznaya, 33, 117418 Moscow, Russia
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5
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5-HT-dependent synaptic plasticity of the prefrontal cortex in postnatal development. Sci Rep 2022; 12:21015. [PMID: 36470912 PMCID: PMC9723183 DOI: 10.1038/s41598-022-23767-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 11/04/2022] [Indexed: 12/12/2022] Open
Abstract
Important functions of the prefrontal cortex (PFC) are established during early life, when neurons exhibit enhanced synaptic plasticity and synaptogenesis. This developmental stage drives the organization of cortical connectivity, responsible for establishing behavioral patterns. Serotonin (5-HT) emerges among the most significant factors that modulate brain activity during postnatal development. In the PFC, activated 5-HT receptors modify neuronal excitability and interact with intracellular signaling involved in synaptic modifications, thus suggesting that 5-HT might participate in early postnatal plasticity. To test this hypothesis, we employed intracellular electrophysiological recordings of PFC layer 5 neurons to study the modulatory effects of 5-HT on plasticity induced by theta-burst stimulation (TBS) in two postnatal periods of rats. Our results indicate that 5-HT is essential for TBS to result in synaptic changes during the third postnatal week, but not later. TBS coupled with 5-HT2A or 5-HT1A and 5-HT7 receptors stimulation leads to long-term depression (LTD). On the other hand, TBS and synergic activation of 5-HT1A, 5-HT2A, and 5-HT7 receptors lead to long-term potentiation (LTP). Finally, we also show that 5-HT dependent synaptic plasticity of the PFC is impaired in animals that are exposed to early-life chronic stress.
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Sala N, Paoli C, Bonifacino T, Mingardi J, Schiavon E, La Via L, Milanese M, Tornese P, Datusalia AK, Rosa J, Facchinetti R, Frumento G, Carini G, Salerno Scarzella F, Scuderi C, Forti L, Barbon A, Bonanno G, Popoli M, Musazzi L. Acute Ketamine Facilitates Fear Memory Extinction in a Rat Model of PTSD Along With Restoring Glutamatergic Alterations and Dendritic Atrophy in the Prefrontal Cortex. Front Pharmacol 2022; 13:759626. [PMID: 35370690 PMCID: PMC8968915 DOI: 10.3389/fphar.2022.759626] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Accepted: 01/25/2022] [Indexed: 12/17/2022] Open
Abstract
Stress represents a major risk factor for psychiatric disorders, including post-traumatic stress disorder (PTSD). Recently, we dissected the destabilizing effects of acute stress on the excitatory glutamate system in the prefrontal cortex (PFC). Here, we assessed the effects of single subanesthetic administration of ketamine (10 mg/kg) on glutamate transmission and dendritic arborization in the PFC of footshock (FS)-stressed rats, along with changes in depressive, anxious, and fear extinction behaviors. We found that ketamine, while inducing a mild increase of glutamate release in the PFC of naïve rats, blocked the acute stress-induced enhancement of glutamate release when administered 24 or 72 h before or 6 h after FS. Accordingly, the treatment with ketamine 6 h after FS also reduced the stress-dependent increase of spontaneous excitatory postsynaptic current (sEPSC) amplitude in prelimbic (PL)-PFC. At the same time, ketamine injection 6 h after FS was found to rescue apical dendritic retraction of pyramidal neurons induced by acute stress in PL-PFC and facilitated contextual fear extinction. These results show rapid effects of ketamine in animals subjected to acute FS, in line with previous studies suggesting a therapeutic action of the drug in PTSD models. Our data are consistent with a mechanism of ketamine involving re-establishment of synaptic homeostasis, through restoration of glutamate release, and structural remodeling of dendrites.
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Affiliation(s)
- Nathalie Sala
- Laboratory of Neuropsychopharmacology and Functional Neurogenomics, Dipartimento di Scienze Farmaceutiche, Università Degli Studi di Milano, Milano, Italy
| | - Caterina Paoli
- Laboratory of Neuropsychopharmacology and Functional Neurogenomics, Dipartimento di Scienze Farmaceutiche, Università Degli Studi di Milano, Milano, Italy.,School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy
| | - Tiziana Bonifacino
- Department of Pharmacy, Unit of Pharmacology and Toxicology, University of Genoa, Genoa, Italy
| | - Jessica Mingardi
- Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | - Emanuele Schiavon
- Department of Biotechnology and Life Sciences, University of Insubria, Busto Arsizio, Italy
| | - Luca La Via
- Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | - Marco Milanese
- Department of Pharmacy, Unit of Pharmacology and Toxicology, University of Genoa, Genoa, Italy
| | - Paolo Tornese
- Laboratory of Neuropsychopharmacology and Functional Neurogenomics, Dipartimento di Scienze Farmaceutiche, Università Degli Studi di Milano, Milano, Italy
| | - Ashok K Datusalia
- Laboratory of Neuropsychopharmacology and Functional Neurogenomics, Dipartimento di Scienze Farmaceutiche, Università Degli Studi di Milano, Milano, Italy.,Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research (NIPER), Raebareli, India
| | - Jessica Rosa
- Laboratory of Neuropsychopharmacology and Functional Neurogenomics, Dipartimento di Scienze Farmaceutiche, Università Degli Studi di Milano, Milano, Italy.,Department of Pharmacology, Medical School of Ribeirão Preto, University of São Paulo, Ribeirao Preto, Brazil
| | - Roberta Facchinetti
- Department of Physiology and Pharmacology "Vittorio Erspamer", SAPIENZA University of Rome, Rome, Italy
| | - Giulia Frumento
- Department of Pharmacy, Unit of Pharmacology and Toxicology, University of Genoa, Genoa, Italy
| | - Giulia Carini
- Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | | | - Caterina Scuderi
- Department of Physiology and Pharmacology "Vittorio Erspamer", SAPIENZA University of Rome, Rome, Italy
| | - Lia Forti
- Department of Biotechnology and Life Sciences, University of Insubria, Busto Arsizio, Italy
| | - Alessandro Barbon
- Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | - Giambattista Bonanno
- Department of Pharmacy, Unit of Pharmacology and Toxicology, University of Genoa, Genoa, Italy.,IRCCS Ospedale Policlinico San Martino, Genoa, Italy
| | - Maurizio Popoli
- Laboratory of Neuropsychopharmacology and Functional Neurogenomics, Dipartimento di Scienze Farmaceutiche, Università Degli Studi di Milano, Milano, Italy
| | - Laura Musazzi
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy
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Moutkine I, Quentin E, Guiard BP, Maroteaux L, Doly S. Heterodimers of serotonin receptor subtypes 2 are driven by 5-HT 2C protomers. J Biol Chem 2017; 292:6352-6368. [PMID: 28258217 DOI: 10.1074/jbc.m117.779041] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 03/02/2017] [Indexed: 11/06/2022] Open
Abstract
The serotonin receptor subtypes 2 comprise 5-HT2A, 5-HT2B, and 5-HT2C, which are Gαq-coupled receptors and display distinct pharmacological properties. Although co-expressed in some brain regions and involved in various neurological disorders, their functional interactions have not yet been studied. We report that 5-HT2 receptors can form homo- and heterodimers when expressed alone or co-expressed in transfected cells. Co-immunoprecipitation and bioluminescence resonance energy transfer studies confirmed that 5-HT2C receptors interact with either 5-HT2A or 5-HT2B receptors. Although heterodimerization with 5-HT2C receptors does not alter 5-HT2C Gαq-dependent inositol phosphate signaling, 5-HT2A or 5-HT2B receptor-mediated signaling was totally blunted. This feature can be explained by a dominance of 5-HT2C on 5-HT2A and 5-HT2B receptor binding; in 5-HT2C-containing heterodimers, ligands bind and activate the 5-HT2C protomer exclusively. This dominant effect on the associated protomer was also observed in neurons, supporting the physiological relevance of 5-HT2 receptor heterodimerization in vivo Accordingly, exogenous expression of an inactive form of the 5-HT2C receptor in the locus ceruleus is associated with decreased 5-HT2A-dependent noradrenergic transmission. These data demonstrate that 5-HT2 receptors can form functionally asymmetric heterodimers in vitro and in vivo that must be considered when analyzing the physiological or pathophysiological roles of serotonin in tissues where 5-HT2 receptors are co-expressed.
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Affiliation(s)
- Imane Moutkine
- From the INSERM UMR-S839, Paris 75005.,the Université Pierre et Marie Curie, Paris 75005.,the Institut du Fer à Moulin, Paris 75005
| | - Emily Quentin
- From the INSERM UMR-S839, Paris 75005.,the Université Pierre et Marie Curie, Paris 75005.,the Institut du Fer à Moulin, Paris 75005
| | - Bruno P Guiard
- the Research Center on Animal Cognition, Center for Integrative Biology, Université Paul Sabatier, UMR5169 CNRS, 118, Route de Narbonne, 31062, Toulouse Cedex 9, France
| | - Luc Maroteaux
- From the INSERM UMR-S839, Paris 75005, .,the Université Pierre et Marie Curie, Paris 75005.,the Institut du Fer à Moulin, Paris 75005
| | - Stephane Doly
- the Institut Cochin, INSERM U1016, CNRS UMR8104, Paris 75014, .,the Université Paris Descartes, Sorbonne Paris Cité, Paris 75014.,the Université Clermont Auvergne, INSERM, NEURO-DOL, F-63000 Clermont-Ferrand, and
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9
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Regional distribution of serotonergic receptors: a systems neuroscience perspective on the downstream effects of the multimodal-acting antidepressant vortioxetine on excitatory and inhibitory neurotransmission. CNS Spectr 2016; 21:162-83. [PMID: 26250622 DOI: 10.1017/s1092852915000486] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Previous work from this laboratory hypothesized that the multimodal antidepressant vortioxetine enhances cognitive function through a complex mechanism, using serotonergic (5-hydroxytryptamine, 5-HT) receptor actions to modulate gamma-butyric acid (GABA) and glutamate neurotransmission in key brain regions like the prefrontal cortex (PFC) and hippocampus. However, serotonergic receptors have circumscribed expression patterns, and therefore vortioxetine's effects on GABA and glutamate neurotransmission will probably be regionally selective. In this article, we attempt to develop a conceptual framework in which the effects of 5-HT, selective serotonin reuptake inhibitors (SSRIs), and vortioxetine on GABA and glutamate neurotransmission can be understood in the PFC and striatum-2 regions with roles in cognition and substantially different 5-HT receptor expression patterns. Thus, we review the anatomy of the neuronal microcircuitry in the PFC and striatum, anatomical data on 5-HT receptor expression within these microcircuits, and electrophysiological evidence on the effects of 5-HT on the behavior of each cell type. This analysis suggests that 5-HT and SSRIs will have markedly different effects within the PFC, where they will induce mixed effects on GABA and glutamate neurotransmission, compared to the striatum, where they will enhance GABAergic interneuron activity and drive down the activity of medium spiny neurons. Vortioxetine is expected to reduce GABAergic interneuron activity in the PFC and concomitantly increase cortical pyramidal neuron firing. However in the striatum, vortioxetine is expected to increase activity at GABAergic interneurons and have mixed excitatory and inhibitory effects in medium spiny neurons. Thus the conceptual framework developed here suggests that vortioxetine will have regionally selective effects on GABA and glutamate neurotransmission.
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Intra- and Interhemispheric Propagation of Electrophysiological Synchronous Activity and Its Modulation by Serotonin in the Cingulate Cortex of Juvenile Mice. PLoS One 2016; 11:e0150092. [PMID: 26930051 PMCID: PMC4773155 DOI: 10.1371/journal.pone.0150092] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Accepted: 02/09/2016] [Indexed: 12/11/2022] Open
Abstract
Disinhibition of the cortex (e.g., by GABA -receptor blockade) generates synchronous and oscillatory electrophysiological activity that propagates along the cortex. We have studied, in brain slices of the cingulate cortex of mice (postnatal age 14–20 days), the propagation along layer 2/3 as well as the interhemispheric propagation through the corpus callosum of synchronous discharges recorded extracellularly and evoked in the presence of 10 μM bicuculline by electrical stimulation of layer 1. The latency of the responses obtained at the same distance from the stimulus electrode was longer in anterior cingulate cortex (ACC: 39.53 ± 2.83 ms, n = 7) than in retrosplenial cortex slices (RSC: 21.99 ± 2.75 ms, n = 5; p<0.05), which is equivalent to a lower propagation velocity in the dorso-ventral direction in ACC than in RSC slices (43.0 mm/s vs 72.9 mm/s). We studied the modulation of this propagation by serotonin. Serotonin significantly increased the latency of the intracortical synchronous discharges (18.9% in the ipsilateral hemisphere and 40.2% in the contralateral hemisphere), and also increased the interhemispheric propagation time by 86.4%. These actions of serotonin were mimicked by the activation of either 5-HT1B or 5-HT2A receptors, but not by the activation of the 5-HT1A subtype. These findings provide further knowledge about the propagation of synchronic electrical activity in the cerebral cortex, including its modulation by serotonin, and suggest the presence of deep differences between the ACC and RSC in the structure of the local cortical microcircuits underlying the propagation of synchronous discharges.
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11
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Activation of 5-hyrdoxytryptamine 7 receptors within the rat nucleus tractus solitarii modulates synaptic properties. Brain Res 2016; 1635:12-26. [PMID: 26779891 DOI: 10.1016/j.brainres.2016.01.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Revised: 01/08/2016] [Accepted: 01/09/2016] [Indexed: 12/22/2022]
Abstract
Serotonin (5-HT) is a potent neuromodulator with multiple receptor types within the cardiorespiratory system, including the nucleus tractus solitarii (nTS)--the central termination site of visceral afferent fibers. The 5-HT7 receptor facilitates cardiorespiratory reflexes through its action in the brainstem and likely in the nTS. However, the mechanism and site of action for these effects is not clear. In this study, we examined the expression and function of 5-HT7 receptors in the nTS of Sprague-Dawley rats. 5-HT7 receptor mRNA and protein were identified across the rostrocaudal extent of the nTS. To determine 5-HT7 receptor function, we examined nTS synaptic properties following 5-HT7 receptor activation in monosynaptic nTS neurons in the in vitro brainstem slice preparation. Application of 5-HT7 receptor agonists altered tractus solitarii evoked and spontaneous excitatory postsynaptic currents which were attenuated with a selective 5-HT7 receptor antagonist. 5-HT7 receptor-mediated changes in excitatory postsynaptic currents were also altered by block of 5-HT1A and GABAA receptors. Interestingly, 5-HT7 receptor activation also reduced the amplitude but not frequency of GABAA-mediated inhibitory currents. Together these results indicate a complex role for 5-HT7 receptors in the nTS that mediate its diverse effects on cardiorespiratory parameters.
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12
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Leiser SC, Li Y, Pehrson AL, Dale E, Smagin G, Sanchez C. Serotonergic Regulation of Prefrontal Cortical Circuitries Involved in Cognitive Processing: A Review of Individual 5-HT Receptor Mechanisms and Concerted Effects of 5-HT Receptors Exemplified by the Multimodal Antidepressant Vortioxetine. ACS Chem Neurosci 2015; 6:970-86. [PMID: 25746856 DOI: 10.1021/cn500340j] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
It has been known for several decades that serotonergic neurotransmission is a key regulator of cognitive function, mood, and sleep. Yet with the relatively recent discoveries of novel serotonin (5-HT) receptor subtypes, as well as an expanding knowledge of their expression level in certain brain regions and localization on certain cell types, their involvement in cognitive processes is still emerging. Of particular interest are cognitive processes impacted in neuropsychiatric and neurodegenerative disorders. The prefrontal cortex (PFC) is critical to normal cognitive processes, including attention, impulsivity, planning, decision-making, working memory, and learning or recall of learned memories. Furthermore, serotonergic dysregulation within the PFC is implicated in many neuropsychiatric disorders associated with prominent symptoms of cognitive dysfunction. Thus, it is important to better understand the overall makeup of serotonergic receptors in the PFC and on which cell types these receptors mediate their actions. In this Review, we focus on 5-HT receptor expression patterns within the PFC and how they influence cognitive behavior and neurotransmission. We further discuss the net effects of vortioxetine, an antidepressant acting through multiple serotonergic targets given the recent findings that vortioxetine improves cognition by modulating multiple neurotransmitter systems.
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Affiliation(s)
| | - Yan Li
- Lundbeck Research USA, Paramus, New Jersey 07650, United States
| | - Alan L. Pehrson
- Lundbeck Research USA, Paramus, New Jersey 07650, United States
| | - Elena Dale
- Lundbeck Research USA, Paramus, New Jersey 07650, United States
| | - Gennady Smagin
- Lundbeck Research USA, Paramus, New Jersey 07650, United States
| | - Connie Sanchez
- Lundbeck Research USA, Paramus, New Jersey 07650, United States
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13
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Ciranna L, Catania MV. 5-HT7 receptors as modulators of neuronal excitability, synaptic transmission and plasticity: physiological role and possible implications in autism spectrum disorders. Front Cell Neurosci 2014; 8:250. [PMID: 25221471 PMCID: PMC4145633 DOI: 10.3389/fncel.2014.00250] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Accepted: 08/06/2014] [Indexed: 12/22/2022] Open
Abstract
Serotonin type 7 receptors (5-HT7) are expressed in several brain areas, regulate brain development, synaptic transmission and plasticity, and therefore are involved in various brain functions such as learning and memory. A number of studies suggest that 5-HT7 receptors could be potential pharmacotherapeutic target for cognitive disorders. Several abnormalities of serotonergic system have been described in patients with autism spectrum disorder (ASD), including abnormal activity of 5-HT transporter, altered blood and brain 5-HT levels, reduced 5-HT synthesis and altered expression of 5-HT receptors in the brain. A specific role for 5-HT7 receptors in ASD has not yet been demonstrated but some evidence implicates their possible involvement. We have recently shown that 5-HT7 receptor activation rescues hippocampal synaptic plasticity in a mouse model of Fragile X Syndrome, a monogenic cause of autism. Several other studies have shown that 5-HT7 receptors modulate behavioral flexibility, exploratory behavior, mood disorders and epilepsy, which include core and co-morbid symptoms of ASD. These findings further suggest an involvement of 5-HT7 receptors in ASD. Here, we review the physiological roles of 5-HT7 receptors and their implications in Fragile X Syndrome and other ASD.
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Affiliation(s)
- Lucia Ciranna
- Department of Biomedical Sciences, University of Catania Catania, Italy
| | - Maria Vincenza Catania
- Institute of Neurological Sciences, the National Research Council of Italy (CNR) Catania, Italy ; Laboratory of Neurobiology, IRCCS Oasi Maria SS Troina, Italy
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14
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Puzerey PA, Decker MJ, Galán RF. Elevated serotonergic signaling amplifies synaptic noise and facilitates the emergence of epileptiform network oscillations. J Neurophysiol 2014; 112:2357-73. [PMID: 25122717 DOI: 10.1152/jn.00031.2014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Serotonin fibers densely innervate the cortical sheath to regulate neuronal excitability, but its role in shaping network dynamics remains undetermined. We show that serotonin provides an excitatory tone to cortical neurons in the form of spontaneous synaptic noise through 5-HT3 receptors, which is persistent and can be augmented using fluoxetine, a selective serotonin re-uptake inhibitor. Augmented serotonin signaling also increases cortical network activity by enhancing synaptic excitation through activation of 5-HT2 receptors. This in turn facilitates the emergence of epileptiform network oscillations (10-16 Hz) known as fast runs. A computational model of cortical dynamics demonstrates that these two combined mechanisms, increased background synaptic noise and enhanced synaptic excitation, are sufficient to replicate the emergence fast runs and their statistics. Consistent with these findings, we show that blocking 5-HT2 receptors in vivo significantly raises the threshold for convulsant-induced seizures.
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Affiliation(s)
- Pavel A Puzerey
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio; and
| | - Michael J Decker
- School of Nursing, Case Western Reserve University, Cleveland, Ohio
| | - Roberto F Galán
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio; and
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15
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Ohta K, Miki T, Warita K, Suzuki S, Kusaka T, Yakura T, Liu J, Tamai M, Takeuchi Y. Prolonged maternal separation disturbs the serotonergic system during early brain development. Int J Dev Neurosci 2013; 33:15-21. [DOI: 10.1016/j.ijdevneu.2013.10.007] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Revised: 10/18/2013] [Accepted: 10/23/2013] [Indexed: 12/14/2022] Open
Affiliation(s)
- Ken‐ichi Ohta
- Department of Anatomy and NeurobiologyFaculty of MedicineKagawa UniversityKagawaJapan
| | - Takanori Miki
- Department of Anatomy and NeurobiologyFaculty of MedicineKagawa UniversityKagawaJapan
| | - Katsuhiko Warita
- Department of Anatomy and NeurobiologyFaculty of MedicineKagawa UniversityKagawaJapan
- Department of PathologyDivision of Molecular DiagnosticsUniversity of Pittsburgh School of MedicinePittsburghPAUSA
| | - Shingo Suzuki
- Department of Anatomy and NeurobiologyFaculty of MedicineKagawa UniversityKagawaJapan
| | - Takashi Kusaka
- Department of PediatricsFaculty of MedicineKagawa UniversityKagawaJapan
| | - Tomiko Yakura
- Department of Anatomy and NeurobiologyFaculty of MedicineKagawa UniversityKagawaJapan
| | - Jun‐Qian Liu
- Department of Anatomy and NeurobiologyFaculty of MedicineKagawa UniversityKagawaJapan
| | - Motoki Tamai
- Department of Anatomy and NeurobiologyFaculty of MedicineKagawa UniversityKagawaJapan
| | - Yoshiki Takeuchi
- Department of Anatomy and NeurobiologyFaculty of MedicineKagawa UniversityKagawaJapan
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16
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Lambe EK, Fillman SG, Webster MJ, Shannon Weickert C. Serotonin receptor expression in human prefrontal cortex: balancing excitation and inhibition across postnatal development. PLoS One 2011; 6:e22799. [PMID: 21829518 PMCID: PMC3146513 DOI: 10.1371/journal.pone.0022799] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Accepted: 07/05/2011] [Indexed: 12/15/2022] Open
Abstract
Serotonin and its receptors (HTRs) play critical roles in brain development and in the regulation of cognition, mood, and anxiety. HTRs are highly expressed in human prefrontal cortex and exert control over prefrontal excitability. The serotonin system is a key treatment target for several psychiatric disorders; however, the effectiveness of these drugs varies according to age. Despite strong evidence for developmental changes in prefrontal Htrs of rodents, the developmental regulation of HTR expression in human prefrontal cortex has not been examined. Using postmortem human prefrontal brain tissue from across postnatal life, we investigated the expression of key serotonin receptors with distinct inhibitory (HTR1A, HTR5A) and excitatory (HTR2A, HTR2C, HTR4, HTR6) effects on cortical neurons, including two receptors which appear to be expressed to a greater degree in inhibitory interneurons of cerebral cortex (HTR2C, HTR6). We found distinct developmental patterns of expression for each of these six HTRs, with profound changes in expression occurring early in postnatal development and also into adulthood. However, a collective look at these HTRs in terms of their likely neurophysiological effects and major cellular localization leads to a model that suggests developmental changes in expression of these individual HTRs may not perturb an overall balance between inhibitory and excitatory effects. Examining and understanding the healthy balance is critical to appreciate how abnormal expression of an individual HTR may create a window of vulnerability for the emergence of psychiatric illness.
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Affiliation(s)
- Evelyn K Lambe
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada.
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17
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Di Pietro NC, Seamans JK. Dopamine and serotonin interactively modulate prefrontal cortex neurons in vitro. Biol Psychiatry 2011; 69:1204-11. [PMID: 20889141 DOI: 10.1016/j.biopsych.2010.08.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2010] [Revised: 08/09/2010] [Accepted: 08/09/2010] [Indexed: 01/06/2023]
Abstract
BACKGROUND Dopamine (DA) and serotonin (5-HT) are released in cortex under similar circumstances, and many psychiatric drugs bind to both types of receptors, yet little is known about how they interact. METHODS To characterize the nature of these interactions, the current study used in vitro patch-clamp recordings to measure the effects of DA and/or 5-HT on pyramidal cells in layer V of the medial prefrontal cortex. RESULTS Either DA or 5-HT applied in isolation increased the evoked excitability of prefrontal cortex neurons, as shown previously. Coapplication of DA and 5-HT produced either a larger increase in excitability than when either was given alone or a significant decrease that was never observed when either was given alone. Dopamine or 5-HT also "primed" neurons to respond in an exaggerated manner to the subsequent application of the other monoamine. CONCLUSIONS These data reveal the unappreciated interactive nature of neuromodulation in cortex by showing that the combined effects of DA and 5-HT can be different from their effects recorded in isolation. On the basis of these findings, we present a theory of how DA and 5-HT might synergistically modulate cortical circuits during various tasks.
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Affiliation(s)
- Nina C Di Pietro
- Brain Research Center, Department of Psychiatry, University of British Columbia, Vancouver, British Columbia, Canada
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18
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Fan LL, Zhang QJ, Liu J, Feng J, Gui ZH, Ali U, Zhang L, Hou C, Wang T, Hui YP, Sun YN, Wu ZH. In vivo effect of 5-HT₇ receptor agonist on pyramidal neurons in medial frontal cortex of normal and 6-hydroxydopamine-lesioned rats: an electrophysiological study. Neuroscience 2011; 190:328-38. [PMID: 21684321 DOI: 10.1016/j.neuroscience.2011.06.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2011] [Revised: 05/30/2011] [Accepted: 06/04/2011] [Indexed: 11/28/2022]
Abstract
The 5-hydroxytryptamine (5-HT)-7 receptor began to be cloned and pharmacologically characterized close to 20 years ago. It couples positively via G-proteins to adenylyl cyclase and activation of this receptor increases neuronal excitability, and several studies have shown that degeneration of the nigrostriatal pathway leads to an impairment of 5-HT system. Here we reported that systemic and local administration of 5-HT₇ receptor agonist AS 19 produced excitation, inhibition and no change in the firing rate of pyramidal neurons in medial prefrontal cortex (mPFC) of normal and 6-hydroxydopamine-lesioned rats. In normal rats, the mean response of the pyramidal neurons to AS 19 by systemic and local administration in mPFC was excitatory. The inhibitory effect by systemic administration of AS 19 was reversed by GABA(A) receptor antagonist picrotoxinin. Systemic administration of picrotoxinin excited all the neurons examined in normal rats, and after treatment with picrotoxinin, the local administration of AS 19 further increased the firing rate of the neurons. In the lesioned rats, systemic administration of AS 19, at the same doses, also increased the mean firing rate of the pyramidal neurons. However, cumulative dose producing excitation in the lesioned rats was higher than that of normal rats. Systemic administration of AS 19 produced inhibitory effect in the lesioned rats, which was partially reversed by picrotoxinin. The local administration of AS 19, at the same dose, did not change the firing rate of the neurons in the lesioned rats. Systemic administration of picrotoxinin and the local administration of AS 19 did not affect the firing rate of the neurons in the lesioned rats. These results indicate that activity of mPFC pyramidal neurons is regulated through activation of 5-HT₇ receptor by direct or indirect action, and degeneration of the nigrostriatal pathway leads to decreased response of these neurons to AS 19, suggesting dysfunction and/or down-regulation of 5-HT₇ receptor on the pyramidal neurons and GABA interneurons in the lesioned rats.
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Affiliation(s)
- L L Fan
- Department of Physiology and Pathophysiology, School of Medicine, Xi'an Jiaotong University, Xi'an 710061, PR China
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19
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Matthys A, Haegeman G, Van Craenenbroeck K, Vanhoenacker P. Role of the 5-HT7 receptor in the central nervous system: from current status to future perspectives. Mol Neurobiol 2011; 43:228-53. [PMID: 21424680 DOI: 10.1007/s12035-011-8175-3] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Accepted: 03/01/2011] [Indexed: 12/11/2022]
Abstract
Pharmacological and genetic tools targeting the 5-hydroxytryptamine (5-HT)7 receptor in preclinical animal models have implicated this receptor in diverse (patho)physiological processes of the central nervous system (CNS). Some data obtained with 5-HT7 receptor knockout mice, selective antagonists, and, to a lesser extent, agonists, however, are quite contradictory. In this review, we not only discuss in detail the role of the 5-HT7 receptor in the CNS but also propose some hypothetical models, which could explain the observed inconsistencies. These models are based on two novel concepts within the field of G protein-coupled receptors (GPCR), namely biphasic signaling and G protein-independent signaling, which both have been shown to be mediated by GPCR dimerization. This led us to suggest that the 5-HT7 receptor could reside in different dimeric contexts and initiate different signaling pathways, depending on the neuronal circuitry and/or brain region. In conclusion, we highlight GPCR dimerization and G protein-independent signaling as two promising future directions in 5-HT7 receptor research, which ultimately might lead to the development of more efficient dimer- and/or pathway-specific therapeutics.
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Affiliation(s)
- Anne Matthys
- Laboratory of Eukaryotic Gene Expression and Signal Transduction (LEGEST), Department of Physiology, Ghent University (UGent), Ghent, Belgium
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20
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Leopoldo M, Lacivita E, Berardi F, Perrone R, Hedlund PB. Serotonin 5-HT7 receptor agents: Structure-activity relationships and potential therapeutic applications in central nervous system disorders. Pharmacol Ther 2010; 129:120-48. [PMID: 20923682 DOI: 10.1016/j.pharmthera.2010.08.013] [Citation(s) in RCA: 140] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2010] [Accepted: 08/26/2010] [Indexed: 12/19/2022]
Abstract
Since its discovery in the 1940s in serum, the mammalian intestinal mucosa, and in the central nervous system, serotonin (5-HT) has been shown to be involved in virtually all cognitive and behavioral human functions, and alterations in its neurochemistry have been implicated in the etiology of a plethora of neuropsychiatric disorders. The cloning of 5-HT receptor subtypes has been of importance in enabling them to be classified as specific protein molecules encoded by specific genes. The 5-HT(7) receptor is the most recently classified member of the serotonin receptor family. Since its identification, it has been the subject of intense research efforts driven by its presence in functionally relevant regions of the brain. The availability of some selective antagonists and agonists, in combination with genetically modified mice lacking the 5-HT(7) receptor, has allowed for a better understanding of the pathophysiological role of this receptor. This paper reviews data on localization and pharmacological properties of the 5-HT(7) receptor, and summarizes the results of structure-activity relationship studies aimed at the discovery of selective 5-HT(7) receptor ligands. Additionally, an overview of the potential therapeutic applications of 5-HT(7) receptor agonists and antagonists in central nervous system disorders is presented.
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Affiliation(s)
- Marcello Leopoldo
- Dipartimento Farmaco-Chimico, Università degli Studi di Bari "A. Moro", via Orabona, 4, 70125 Bari, Italy.
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21
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Sidor MM, Amath A, MacQueen G, Foster JA. A developmental characterization of mesolimbocortical serotonergic gene expression changes following early immune challenge. Neuroscience 2010; 171:734-46. [PMID: 20816924 DOI: 10.1016/j.neuroscience.2010.08.060] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2010] [Revised: 08/25/2010] [Accepted: 08/30/2010] [Indexed: 12/15/2022]
Abstract
An immunogenic challenge during early postnatal development leads to long-term changes in behavioural and physiological measures reflecting enhanced emotionality and anxiety. Altered CNS serotonin (5-HT) signalling during the third postnatal week is thought to modify the developing neurocircuitry governing anxiety-like behaviour. Changes in 5-HT signalling during this time window may underlie increased emotionality reported in early immune challenge rodents. Here we examine both the spatial and temporal profile of 5-HT related gene expression, including 5HT1A, 2A, 2C receptors, the 5-HT transporter (5HTT), and tryptophan hydroxylase 2 (TPH2) during early development (postnatal day [P]14, P17, P21, P28) in mice challenged with lipopolysaccharide (LPS) during the first postnatal week. Expression levels were measured using in situ hybridization in regions associated with mediating emotive behaviours: the dorsal raphe (DR), hippocampus, amygdala, and prefrontal cortex (PFC). Increased TPH2 and 5HTT expression in the ventrolateral region of the DR of LPS-mice accompanied decreased expression of ventral DR 5HT1A and dorsal DR 5HTT. In the forebrain, 5HT1A and 2A receptors were increased, whereas 5HT2C receptors were decreased in the hippocampus. Decreased mRNA expression of 5HT2C was detected in the amygdala and PFC of LPS-treated pups; 5HT1A was increased in the PFC. The majority of these changes were restricted to P14-21. These transient changes in 5-HT expression coincide with the critical time window in which 5-HT disturbance leads to permanent modification of anxiety-related behaviours. This suggests that alterations in CNS 5-HT during development may underlie the enhanced emotionality associated with an early immune challenge.
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Affiliation(s)
- M M Sidor
- Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, ON, Canada
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22
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Andrade R, Beck SG. Cellular Effects of Serotonin in the CNS. HANDBOOK OF BEHAVIORAL NEUROSCIENCE 2010. [DOI: 10.1016/s1569-7339(10)70080-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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23
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Repeated cocaine administration decreases 5-HT(2A) receptor-mediated serotonergic enhancement of synaptic activity in rat medial prefrontal cortex. Neuropsychopharmacology 2009; 34:1979-92. [PMID: 19212317 DOI: 10.1038/npp.2009.10] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Neural adaptations in the medial prefrontal cortex (mPFC) are thought to be crucial in the development and maintenance of addictive behaviors. The mPFC receives a dense serotonergic (5-hydroxytryptamine, 5-HT) innervation from raphe nuclei and 5-HT exerts complex actions on mPFC pyramidal neurons. The present study, using a rat model of behavioral sensitization to cocaine, was designed to determine whether repeated cocaine exposure in vivo is capable of altering 5-HT-induced regulation of glutamatergic transmission in the mPFC. In layer V pyramidal neurons of the mPFC, application of 5-HT, through activation of 5-HT(2A) receptors, induced a massive enhancement of spontaneous excitatory postsynaptic currents (sEPSCs). Repeated cocaine administration for 5 days resulted in an attenuation in the ability of 5-HT to enhance sEPSCs. This effect was prevented when cocaine was co-administered with the selective 5-HT(2A) receptor antagonist ketanserin and was mimicked by repeated 5-HT(2A) receptor agonist (-)4-iodo-2,5-dimethoxyphenylisopropylamine administration. Repeated cocaine administration is not associated with any changes in the levels of 5-HT(2A) receptors or regulator of GTP-binding protein signaling 4. These results suggest that cocaine-induced inhibition of 5-HT(2A) receptor-mediated enhancement of glutamatergic transmission in the mPFC may be caused, at least in part, by the impairment of coupling of 5-HT(2A) receptors with GTP-binding proteins during cocaine withdrawal. These alterations in 5-HT(2A) receptor responsiveness in the mPFC may be relevant to the development of behavioral sensitization and withdrawal effects following repeated cocaine administration.
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24
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Leal K, Klein M. Direct enhancement of presynaptic calcium influx in presynaptic facilitation at Aplysia sensorimotor synapses. Mol Cell Neurosci 2009; 41:247-57. [PMID: 19344767 DOI: 10.1016/j.mcn.2009.03.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2009] [Revised: 03/01/2009] [Accepted: 03/23/2009] [Indexed: 01/20/2023] Open
Abstract
Regulation of synaptic transmission by modulation of the calcium influx that triggers transmitter release underlies different forms of synaptic plasticity, and thus could contribute to learning. In the mollusk Aplysia, the neuromodulator serotonin (5-HT) increases evoked transmitter release from sensory neurons and thereby contributes to dishabituation and sensitization of defensive reflexes. We combined electrophysiological recording with fluorescence measurements of intracellular calcium in sensory neuron synapses in culture to test whether direct up-modulation by 5-HT of calcium influx triggered by single action potentials contributes to facilitation of transmitter release. We observe increases in a previously undescribed calcium influx that are strongly correlated with increases in the amplitude of the evoked postsynaptic potentials and which cannot be accounted for by action potential prolongation. Our results suggest that direct modulation of a presynaptic calcium conductance that controls neurotransmitter release contributes to the presynaptic facilitation that underlies a simple form of learning.
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Affiliation(s)
- Karina Leal
- Department of Physiological Science and Brain Research Institute, University of California at Los Angeles, 621 Charles Young Drive South, Los Angeles, CA 90095, USA.
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25
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Matsumoto M, Yoshioka M, Togashi H. Chapter 7 Early Postnatal Stress and Neural Circuit Underlying Emotional Regulation. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2009; 85:95-107. [DOI: 10.1016/s0074-7742(09)85007-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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26
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Pascucci T, Andolina D, Ventura R, Puglisi-Allegra S, Cabib S. Reduced availability of brain amines during critical phases of postnatal development in a genetic mouse model of cognitive delay. Brain Res 2008; 1217:232-8. [PMID: 18502400 DOI: 10.1016/j.brainres.2008.04.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2007] [Revised: 04/02/2008] [Accepted: 04/04/2008] [Indexed: 10/22/2022]
Abstract
Serotonin (5-HT), dopamine (DA) and noradrenaline (NE) play important roles in brain postnatal maturation. Therefore, deficits in brain availability of biogenic amines during critical developmental phases might underlie neurodevelopmental disturbances associated with cognitive impairment. To test this hypothesis we evaluated brain availability of 5-HT, DA and NE, of their immediate precursors 5-hydroxytryptophan and 3,4-dihydroxy-l-phenylalanine, and of large neutral amino acids phenylalanine, tyrosine and tryptophan, in developing PahEnu2 mice, the genetic model of Phenylketonuria (PKU) a cause of severe cognitive delay. We found deficits of brain amine levels in PKU pups between day 14 and 35 of postnatal life, when pups of the healthy background showed developmental peak increases of amines and precursors. 5-HT deficits were most pronounced, were unrelated with brain availability of the amino acid precursor tryptophan, but overlapped with peak brain phenylalanine concentrations and reduced availability of 5-HT direct precursor 5-hydroxytryptophan. These results identify a critical window of brain amine availability susceptible to disturbances in a genetic mouse model of pathological neurodevelopment and suggest a mechanism of interference with brain aminergic synthesis in PKU and non-PKU hyperphenylalaninemia.
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Affiliation(s)
- Tiziana Pascucci
- Dipartimento di Psicologia and Centro Daniel Bovet, Sapienza University, Rome, Italy.
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27
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Serotonin pharmacology in the gastrointestinal tract: a review. Naunyn Schmiedebergs Arch Pharmacol 2008; 377:181-203. [PMID: 18398601 DOI: 10.1007/s00210-008-0276-9] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2007] [Accepted: 02/15/2008] [Indexed: 12/17/2022]
Abstract
Serotonin (5-hydroxytryptamine or 5-HT) plays a critical physiological role in the regulation of gastrointestinal (GI) function. 5-HT dysfunction may also be involved in the pathophysiology of a number of functional GI disorders, such as chronic constipation, irritable bowel syndrome and functional dyspepsia. This article describes the role of 5-HT in the enteric nervous system (ENS) of the mammalian GI tract and the receptors with which it interacts. Existing serotonergic therapies that have proven effective in the treatment of GI functional disorders and the potential of drugs currently in development are also highlighted. Advances in our understanding of the physiological and pathophysiological roles of 5-HT in the ENS and the identification of selective receptor ligands bodes well for the future development of more efficacious therapies for patients with functional GI disorders.
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28
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Wang HT, Luo B, Huang YN, Zhou KQ, Chen L. Sodium salicylate suppresses serotonin-induced enhancement of GABAergic spontaneous inhibitory postsynaptic currents in rat inferior colliculus in vitro. Hear Res 2008; 236:42-51. [DOI: 10.1016/j.heares.2007.11.015] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2007] [Revised: 11/27/2007] [Accepted: 11/27/2007] [Indexed: 10/22/2022]
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29
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30
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Ho SSN, Chow BKC, Yung WH. Serotonin increases the excitability of the hypothalamic paraventricular nucleus magnocellular neurons. Eur J Neurosci 2007; 25:2991-3000. [PMID: 17561813 DOI: 10.1111/j.1460-9568.2007.05547.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Recent evidence that 5-hydroxytryptamine (5-HT or serotonin) enhances the release and the gene expression of vasopressin and oxytocin in the hypothalamic paraventricular nucleus (PVN) suggests that 5-HT can excite the PVN magnocellular neurons. The objective of this study was to examine the underlying mechanisms for such excitatory action in the electrophysiologically identified hypothalamic PVN magnocellular neurons in rats using whole-cell patch-clamp. We found that 5-HT weakly depolarizes 33.3% of PVN magnocellular neurons in the presence of tetrodotoxin. A minuscule inward current was produced by 5-HT in 48% of the cells, which was attenuated when the 5-HT(4) antagonist GR113808 or the 5-HT(7) antagonist SB269970 was added. In addition, 5-HT reduced the frequency of miniature inhibitory postsynaptic currents in a dose-dependent manner. This inhibition was mimicked by the 5-HT(1B) agonist CP93129, and reversed in the presence of 5-HT(1B) antagonists cyanopindolol and SB224289. Besides, 5-HT induced a biphasic effect on the frequency of miniature excitatory postsynaptic currents, comprising a transient inhibition and a delayed concentration-dependent excitation (onset latency approximately 5 min). The facilitation was mimicked by the 5-HT(2A/2C) agonist DOI and abolished in the presence of the 5-HT(2C) antagonist RS102221. Our findings reveal that 5-HT directly increases the excitability of the PVN magnocellular neurons via multiple receptor subtypes and mechanisms. This may help understanding the regulation of 5-HT-induced hormone release and feeding behavior in the PVN.
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Affiliation(s)
- Sara S N Ho
- Department of Zoology, The University of Hong Kong, Pokfulam, Hong Kong, China
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31
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Fantegrossi WE, Murnane KS, Reissig CJ. The behavioral pharmacology of hallucinogens. Biochem Pharmacol 2007; 75:17-33. [PMID: 17977517 DOI: 10.1016/j.bcp.2007.07.018] [Citation(s) in RCA: 133] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2007] [Revised: 07/11/2007] [Accepted: 07/13/2007] [Indexed: 11/25/2022]
Abstract
Until very recently, comparatively few scientists were studying hallucinogenic drugs. Nevertheless, selective antagonists are available for relevant serotonergic receptors, the majority of which have now been cloned, allowing for reasonably thorough pharmacological investigation. Animal models sensitive to the behavioral effects of the hallucinogens have been established and exploited. Sophisticated genetic techniques have enabled the development of mutant mice, which have proven useful in the study of hallucinogens. The capacity to study post-receptor signaling events has lead to the proposal of a plausible mechanism of action for these compounds. The tools currently available to study the hallucinogens are thus more plentiful and scientifically advanced than were those accessible to earlier researchers studying the opioids, benzodiazepines, cholinergics, or other centrally active compounds. The behavioral pharmacology of phenethylamine, tryptamine, and ergoline hallucinogens are described in this review, paying particular attention to important structure activity relationships which have emerged, receptors involved in their various actions, effects on conditioned and unconditioned behaviors, and in some cases, human psychopharmacology. As clinical interest in the therapeutic potential of these compounds is once again beginning to emerge, it is important to recognize the wealth of data derived from controlled preclinical studies on these compounds.
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Affiliation(s)
- William E Fantegrossi
- Division of Neuroscience, Yerkes National Primate Research Center, Emory University, 954 Gatewood Road NE, Atlanta, GA 30322, USA.
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Parga J, Rodriguez-Pallares J, Muñoz A, Guerra MJ, Labandeira-Garcia JL. Serotonin decreases generation of dopaminergic neurons from mesencephalic precursors via serotonin type 7 and type 4 receptors. Dev Neurobiol 2007; 67:10-22. [PMID: 17443768 DOI: 10.1002/dneu.20306] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Inductive signals mediating the differentiation of neural precursors into serotonergic (5-HT) or dopaminergic neurons have not been clarified. We have recently shown that in cell aggregates obtained from rat mesencephalic precursors, reduction of serotonin levels induces a marked increase in generation of dopaminergic neurons. In the present study we treated rat neurospheres with antagonists of the main subtypes of 5-HT receptors, 5-HT transport inhibitors, or 5-HT receptor agonists, and studied the effects on generation of dopaminergic neurons. Cultures treated with Methiothepin (5-HT(1,2,5,6,7) receptor antagonist), the 5-HT(4) receptor antagonist GR113808;67:00-.or the 5-HT(7) receptor antagonist SB 269970 showed a significant increase in generation of dopaminergic cells. Treatment with the 5-HT(1B/1D) antagonist GR 127935, the 5-HT(2) antagonist Ritanserin, the 5-HT transporter inhibitor Fluoxetine, the dopamine and norepinephrine transport inhibitor GBR 12935, or with both inhibitors together, or 5-HT(4) or 5-HT(7) receptor agonists induced significant decreases in generation of dopaminergic cells. Cultures treated with WAY100635 (5-HT(1A) receptor antagonist), the 5-HT(3) receptor antagonist Ondasetron, or the 5-HT(6) receptor antagonist SB 258585 did not show any significant changes. Therefore, 5-HT(4) and 5-HT(7) receptors are involved in the observed serotonin-induced decrease in generation of dopaminergic neurons from proliferating neurospheres of mesencephalic precursors. 5-HT(4) and 5-HT(7) receptors were found in astrocytes and serotonergic cells using double immunolabeling and laser confocal microscopy, and the glial receptors appeared to play a major role.
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Affiliation(s)
- J Parga
- Laboratory of Neuroanatomy and Experimental Neurology, Department of Morphological Sciences, Faculty of Medicine, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain
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Béïque JC, Imad M, Mladenovic L, Gingrich JA, Andrade R. Mechanism of the 5-hydroxytryptamine 2A receptor-mediated facilitation of synaptic activity in prefrontal cortex. Proc Natl Acad Sci U S A 2007; 104:9870-5. [PMID: 17535909 PMCID: PMC1887564 DOI: 10.1073/pnas.0700436104] [Citation(s) in RCA: 157] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Classic hallucinogens such as lysergic acid diethylamide are thought to elicit their psychotropic actions via serotonin receptors of the 5-hydroxytryptamine 2A subtype (5-HT(2A)R). One likely site for these effects is the prefrontal cortex (PFC). Previous studies have shown that activation of 5-HT(2A)Rs in this region results in a robust increase in spontaneous glutamatergic synaptic activity, and these results have led to the widely held idea that hallucinogens elicit their effect by modulating synaptic transmission within the PFC. Here, we combine cellular and molecular biological approaches, including single-cell 5-HT(2A)Rs inactivation and 5-HT(2A)R rescue over a 5-HT(2A)R knockout genetic background, to distinguish between competing hypotheses accounting for these effects. The results from these experiments do not support the idea that 5-HT(2A)Rs elicit the release of an excitatory retrograde messenger nor that they activate thalamocortical afferents, the two dominant hypotheses. Rather, they suggest that 5-HT(2A)Rs facilitate intrinsic networks within the PFC. Consistent with this idea, we locate a discrete subpopulation of pyramidal cells that is strongly excited by 5-HT(2A)R activation.
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Affiliation(s)
| | - Mays Imad
- Cellular and Clinical Neurobiology Training Program, Wayne State University School of Medicine, Detroit, MI 48201; and
| | | | - Jay A. Gingrich
- Department of Psychiatry, College of Physicians and Surgeons, Columbia University, New York, NY 10032
| | - Rodrigo Andrade
- Department of Pharmacology
- *Department of Psychiatry and Behavioral Neurosciences, and
- To whom correspondence should be addressed at:
Department of Pharmacology, Wayne State University School of Medicine, 540 East Canfield, Detroit, MI 48201. E-mail:
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Ehret A, Birthelmer A, Rutz S, Riegert C, Rothmaier AK, Jackisch R. Agonist-mediated regulation of presynaptic receptor function during development of rat septal neurons in culture. J Neurochem 2007; 102:1071-82. [PMID: 17472710 DOI: 10.1111/j.1471-4159.2007.04598.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Presynaptic receptors modulating the release of acetylcholine (ACh) were studied in fetal septal neurons cultured in a growth medium to which various drugs were added from day 3 in vitro (DIV 3) to DIV 14. The influence of these drugs on the function of the presynaptic muscarinic (M-) autoreceptor was determined at DIV 14 by measuring the inhibitory effect of the M-agonist oxotremorine on the electrically-evoked release of [(3)H]ACh from cultures pre-incubated with [(3)H]choline. The presence of the M-agonists oxotremorine (100 micromol/L) or carbachol (100 micromol/L) from DIV 3 to DIV 14, or from DIV 13 to DIV 14, abolished M-autoreceptor function at DIV 14, whereas the presence of the M-antagonist atropine (10 micromol/L from DIV 3 to DIV 14) during growth left M-autoreceptor function unaltered. Inhibition of ACh esterase by donepezil (1 micromol/L from DIV 3 to DIV 14) weakly decreased M-autoreceptor function at DIV 14; inhibition of neuronal firing by 0.1 tetrodotoxin (0.1 micromol/L from DIV 3 to DIV 14) did not tend to affect M-autoreceptor function at DIV 14. Co-cultivation of fetal septal and raphe neurons for 2 weeks yielded cell cultures containing both vesicular ACh transporter- and tryptophan hydroxylase-immunopositive cells. From these cultures, the release of both [(3)H]ACh and [(3)H]5-HT could be induced by electrical field stimulation. In co-cultured neurons versus septal-only ones the inhibitory effect of oxotremorine on the evoked release of [(3)H]ACh appeared almost normal, whereas that of the selective 5-HT(1B) agonist 3-(1,2,5,6-tetrahydropyrid-4-yl)pyrrollo[3,2-b]pyrid-5-one (CP-93,129) was completely abolished. The effects of CP-93,129 were also absent on DIV 14 in septal mono-cultures grown in the presence of CP-93,129 (10 micromol/L) from DIV 3 to DIV 14. It is therefore concluded that the regulation of presynaptic receptor function strongly depends on the concentrations of endogenous transmitters in the neuronal environment.
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Affiliation(s)
- Andreas Ehret
- Laboratory of Neuropharmacology, Institute for Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, Hansastrasse, Freiburg, Germany
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Brunelli SA, Hofer MA. Selective breeding for infant rat separation-induced ultrasonic vocalizations: developmental precursors of passive and active coping styles. Behav Brain Res 2007; 182:193-207. [PMID: 17543397 PMCID: PMC2759113 DOI: 10.1016/j.bbr.2007.04.014] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2007] [Revised: 04/17/2007] [Accepted: 04/20/2007] [Indexed: 11/26/2022]
Abstract
Human depression and anxiety disorders show inherited biases across generations, as do antisocial disorders characterized by aggression. Each condition is preceded in children by behavioral inhibition or aggressive behavior, respectively, and both are characterized by separation anxiety disorders. In affected families, adults and children exhibit different forms of altered autonomic nervous system regulation and hypothalamic-pituitary-adrenal activity in response to stress. Because it is difficult to determine mechanisms accounting for these associations, animal studies are useful for studying the fundamental relationships between biological and behavioral traits. Pharmacologic and behavioral studies suggest that infant rat ultrasonic vocalizations (USV) are a measure of an early anxiety-like state related to separation anxiety. However, it was not known whether or not early ultrasound emissions in infant rats are markers for genetic risk for anxiety states later in life. To address these questions, we selectively bred two lines of rats based on high and low rates of USV to isolation at postnatal (P) 10 days of age. To our knowledge, ours is the only laboratory that has ever selectively bred on the basis of an infantile trait related to anxiety. The High and Low USV lines show two distinct sets of patterns of behavior, physiology and neurochemistry from infancy through adulthood. As adults High line rats demonstrate "anxious"/"depressed" phenotypes in behavior and autonomic nervous system (ANS) regulation to standard laboratory tests. In Lows, on the other hand, behavior and autonomic regulation are consistent with an "aggressive" phenotype. The High and Low USV lines are the first genetic animal models implicating long-term associations of contrasting "coping styles" with early attachment responses. They thus present a potentially powerful model for examining gene-environment interactions in the development of life-long affective regulation.
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Affiliation(s)
- Susan A Brunelli
- Developmental Neuroscience, New York State Psychiatric Institute, New York, NY 10032,
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Huang YY, Kandel ER. 5-Hydroxytryptamine induces a protein kinase A/mitogen-activated protein kinase-mediated and macromolecular synthesis-dependent late phase of long-term potentiation in the amygdala. J Neurosci 2007; 27:3111-9. [PMID: 17376972 PMCID: PMC6672482 DOI: 10.1523/jneurosci.3908-06.2007] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The amygdala is a critical site for the acquisition of learned fear memory in mammals, and the formation and long-term maintenance of fear memories are thought to be associated with changes of synaptic strength in the amygdala. Here we report that serotonin (5-hydroxytryptamine; 5-HT), a modulatory neurotransmitter known to be linked to learned fearful and emotional behavior, has dual effects on excitatory synaptic transmission in the basolateral amygdala. There is an early depression of synaptic transmission lasting 30-50 min, mediated by 5-HT1A, and a late, long-lasting facilitation lasting >5 h in slice recordings, mediated by the 5-HT4 receptor. 5-HT late phase long-term potentiation (L-LTP) is blocked by inhibitors of either protein kinase A (PKA) and/or mitogen-activated kinase (MAPK) and requires new protein synthesis and gene transcription. Moreover, the 5-HT-induced L-LTP in neurons of amygdala is blocked by the actin inhibitor cytochalasin D, suggesting that 5-HT stimulates a cytoskeletal rearrangement. These results show, for the first time, that 5-HT can produce long-lasting facilitation of synaptic transmission in the amygdala and provides evidence for the possible synaptic role of 5-HT in long-term memory for learned fear.
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Affiliation(s)
- Yan-You Huang
- Center for Neurobiology and Behavior of the College of Physicians and Surgeons of Columbia University
| | - Eric R. Kandel
- Kavli Institute for Brain Science
- Center for Neurobiology and Behavior of the College of Physicians and Surgeons of Columbia University
- New York State Psychiatric Institute, and
- Howard Hughes Medical Institute, Columbia University, New York, New York 10032
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37
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Hall IC, Hurley LM. The serotonin releaser fenfluramine alters the auditory responses of inferior colliculus neurons. Hear Res 2007; 228:82-94. [PMID: 17339086 PMCID: PMC1950579 DOI: 10.1016/j.heares.2007.01.023] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2006] [Revised: 01/19/2007] [Accepted: 01/22/2007] [Indexed: 10/23/2022]
Abstract
Local direct application of the neuromodulator serotonin strongly influences auditory response properties of neurons in the inferior colliculus (IC), but endogenous stores of serotonin may be released in a distinct spatial or temporal pattern. To explore this issue, the serotonin releaser fenfluramine was iontophoretically applied to extracellularly recorded neurons in the IC of the Mexican free-tailed bat (Tadarida brasiliensis). Fenfluramine mimicked the effects of serotonin on spike count and first spike latency in most neurons, and its effects could be blocked by co-application of serotonin receptor antagonists, consistent with fenfluramine-evoked serotonin release. Responses to fenfluramine did not vary during single applications or across multiple applications, suggesting that fenfluramine did not deplete serotonin stores. A predicted gradient in the effects of fenfluramine with serotonin fiber density was not observed, but neurons with fenfluramine-evoked increases in latency occurred at relatively greater recording depths compared to other neurons with similar characteristic frequencies. These findings support the conclusion that there may be spatial differences in the effects of exogenous and endogenous sources of serotonin, but that other factors such as the identities and locations of serotonin receptors are also likely to play a role in determining the dynamics of serotonergic effects.
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Affiliation(s)
- Ian C Hall
- Department of Biology, 1001 E. Third St, 342 Jordan Hall, Indiana University, Bloomington, IN 47405, USA.
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38
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Parga J, Rodriguez-Pallares J, Muñoz A, Guerra MJ, Labandeira-Garcia J. Serotonin decreases generation of dopaminergic neurons from mesencephalic precursors via serotonin type 7 and type 4 receptors. ACTA ACUST UNITED AC 2007. [DOI: 10.1002/neu.20306] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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39
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Mair RD, Kauer JA. Amphetamine depresses excitatory synaptic transmission at prefrontal cortical layer V synapses. Neuropharmacology 2007; 52:193-9. [PMID: 16895728 DOI: 10.1016/j.neuropharm.2006.07.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2006] [Revised: 06/30/2006] [Accepted: 07/03/2006] [Indexed: 11/24/2022]
Abstract
Dopamine modulates the function of glutamatergic synapses in prefrontal cortex, modifying synaptic strength and influencing synaptic plasticity. Here we have explored the ability of endogenous dopamine, present in slices containing the prefrontal cortex, to influence excitatory synaptic transmission. We found that 10 microM amphetamine, which releases and blocks the reuptake of dopamine from dopaminergic nerve terminals, significantly depressed excitatory field potentials recorded in layer V during stimulation of layer II/III. The depression was reversible, dose dependent and correlated with increased paired pulse facilitation, suggesting that amphetamine inhibits the presynaptic release of glutamate. Pharmacological dissection of this response showed that dopamine D1 receptors are likely to mediate the effects of endogenous dopamine on excitatory synaptic transmission, with little effect of alpha2 adrenergic receptors, serotonin receptors, or D2 dopamine receptors. The time to peak amphetamine effect was longer than expected based on diffusion, suggesting that to raise dopamine levels in brain slices amphetamine may need to be transported into the presynaptic terminals. These results provide evidence that D1/D5 receptors depress glutamate release at this cortical synapse, and suggest that amphetamine will have profound and persistent effects on PFC functioning in vivo. Dysregulation of this mechanism could contribute to the impairment in cognitive performance associated with abnormal PFC dopamine receptor activation.
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Affiliation(s)
- Robert D Mair
- Department of Molecular Pharmacology, Physiology and Biotechnology, Box G-B4, Brown University, Providence, RI 02912, USA
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40
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Bianchi C, Marani L, Marino S, Barbieri M, Nazzaro C, Beani L, Siniscalchi A. Serotonin modulation of cell excitability and of [3H]GABA and [3H]D-aspartate efflux in primary cultures of rat cortical neurons. Neuropharmacology 2006; 52:995-1002. [PMID: 17156800 DOI: 10.1016/j.neuropharm.2006.10.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2006] [Revised: 10/25/2006] [Accepted: 10/28/2006] [Indexed: 11/25/2022]
Abstract
The effects of 5-hydroxytryptamine (5-HT) on neuronal excitability, evaluated as depolarization-induced firing rate, and on amino acid release, measured as electrically-evoked [(3)H]GABA and [(3)H]d-aspartate efflux, were investigated in rat primary cortical neuronal cultures. 5-HT displayed a concentration-dependent, bimodal effect on neuronal excitability: at 3-10microM it increased excitability through 5-HT(2A) receptors, and was blocked by the selective 5-HT(2A) antagonist MDL 100907, whereas at 30-100microM it reduced excitability through 5-HT(1A) receptors, and was, in turn, blocked by the selective 5-HT(1A) antagonist WAY 100135. The electrically-evoked [(3)H]GABA efflux was concentration-dependently inhibited by 5-HT (pEC(50)=4.74) and such inhibition was prevented by WAY 100135, but not by GR 55562, a selective 5-HT(1D/B) receptor antagonist. Conversely, 5-HT concentration-dependently increased stimulus-evoked [(3)H]d-aspartate efflux (pEC(50)=4.71). The increase was facilitated by methiothepin and was reversed into inhibition by ICS 205930, a selective 5-HT(3) receptor antagonist. In the presence of ICS 205930, the inhibition induced by 5-HT was prevented by the selective 5-HT(1D/B) receptor antagonist GR 55562, but not by WAY 100135. These findings suggest that 5-HT inhibits GABA release through 5-HT(1A) receptors and exerts a dual modulation on glutamate release, mostly facilitatory (through 5-HT(3) receptors) but also inhibitory (through 5-HT(1D/B) receptors), leading to a prevalently positive modulation of the excitatory signal by amino acid neurotransmitter containing neurons.
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Affiliation(s)
- C Bianchi
- Department of Clinical and Experimental Medicine, Section of Pharmacology and Neuroscience Center, University of Ferrara, Via Fossato di Mortara 17-19, 44100 Ferrara, Italy
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Dean B, Pavey G, Thomas D, Scarr E. Cortical serotonin7, 1D and 1F receptors: effects of schizophrenia, suicide and antipsychotic drug treatment. Schizophr Res 2006; 88:265-74. [PMID: 16916599 DOI: 10.1016/j.schres.2006.07.003] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2006] [Revised: 06/30/2006] [Accepted: 07/05/2006] [Indexed: 11/21/2022]
Abstract
Abnormalities in serotonergic function are thought to be important in the pathology of schizophrenia. Postmortem CNS studies suggest that levels of serotonin receptors may be altered in the cortex of subjects with schizophrenia. Seeking to expand this hypothesis we have examined the effect of schizophrenia and antipsychotic drug treatments on the levels of cortical serotonin7, 1D and 1F receptors. There was a significant decrease in the binding of [3H]SB 269970 to the serotonin7 receptor in Brodmann's area 9 from subjects with schizophrenia compared to controls (Mean+/-S.E.M.: 8.3+/-0.76 vs. 11.0+/-0.64 fmol/mg ETE; p<0.05) and an increase in the binding of that radioligand in the cortex of rats treated with haloperidol (p=0.03). There were no significant differences in [3H]sumatriptan binding to the serotonin1D or serotonin1F receptor in Brodmann's area 9 from subjects with schizophrenia. There was a significant increase in [3H]sumatriptan binding to the serotonin1D in binding Layer 2 from subjects who had potentially died by suicide that was not present in other binding layers or for the serotonin1F or serotonin7 receptors. There was decrease in [3H]sumatriptan binding to the serotonin1D, but not serotonin1F, receptors across all cortical binding layers in rats treated with haloperidol. These data would be consistent with the hypothesis that decreased levels of serotonin7 receptors in Brodmann's area 9 may be involved in the pathological processes of schizophrenia and that levels of cortical serotonin7 and 1D receptors can be affected by antipsychotic drug treatment.
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Affiliation(s)
- Brian Dean
- The Rebecca L. Cooper Research Laboratories, The Mental Health Research Institute, The University of Melbourne, Australia.
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Hurley LM. Different serotonin receptor agonists have distinct effects on sound-evoked responses in inferior colliculus. J Neurophysiol 2006; 96:2177-88. [PMID: 16870843 PMCID: PMC2579767 DOI: 10.1152/jn.00046.2006] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The neuromodulator serotonin has a complex set of effects on the auditory responses of neurons within the inferior colliculus (IC), a midbrain auditory nucleus that integrates a wide range of inputs from auditory and nonauditory sources. To determine whether activation of different types of serotonin receptors is a source of the variability in serotonergic effects, four selective agonists of serotonin receptors in the serotonin (5-HT) 1 and 5-HT2 families were iontophoretically applied to IC neurons, which were monitored for changes in their responses to auditory stimuli. Different agonists had different effects on neural responses. The 5-HT1A agonist had mixed facilitatory and depressive effects, whereas 5-HT1B and 5-HT2C agonists were both largely facilitatory. Different agonists changed threshold and frequency tuning in ways that reflected their effects on spike count. When pairs of agonists were applied sequentially to the same neurons, selective agonists sometimes affected neurons in ways that were similar to serotonin, but not to other selective agonists tested. Different agonists also differentially affected groups of neurons classified by the shapes of their frequency-tuning curves, with serotonin and the 5-HT1 receptors affecting proportionally more non-V-type neurons relative to the other agonists tested. In all, evidence suggests that the diversity of serotonin receptor subtypes in the IC is likely to account for at least some of the variability of the effects of serotonin and that receptor subtypes fulfill specialized roles in auditory processing.
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Affiliation(s)
- Laura M Hurley
- Biology Department, Indiana University, 1001 E. Third St., Jordan Hall, Bloomington, IN 47405, USA.
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Rutz S, Riegert C, Rothmaier AK, Buhot MC, Cassel JC, Jackisch R. Presynaptic serotonergic modulation of 5-HT and acetylcholine release in the hippocampus and the cortex of 5-HT1B-receptor knockout mice. Brain Res Bull 2006; 70:81-93. [PMID: 16750486 DOI: 10.1016/j.brainresbull.2006.04.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2006] [Revised: 04/03/2006] [Accepted: 04/07/2006] [Indexed: 12/28/2022]
Abstract
Lesioning of serotonergic afferents increases hippocampal ACh release and attenuates memory deficits produced by cholinergic lesions. Improved memory performance described in 5-HT1B-knockout (KO) mice might thus be due to a weaker 5-HT1B-mediated inhibitory influence of 5-HT on hippocampal ACh release. The selective delay-dependent impairment of working memory observed in these KO mice suggests, however, that cortical regions also participate in task performance, possibly via indirect influences of 5-HT on ACh release. To provide neuropharmacological support for these hypotheses we measured evoked ACh and 5-HT release in hippocampal and cortical slices of wild-type (WT) and 5-HT1B KO mice. Superfused slices (preincubated with [3H]choline or [3H]5-HT) were electrically stimulated in the absence or presence of 5-HT1B receptor ligands. In hippocampus and cortex, 5-HT1B agonists decreased and antagonists increased 5-HT release in WT, but not in 5-HT1B KO mice. In 5-HT1B KO mice, 5-HT release was enhanced in both structures, while ACh release (in nCi) was reduced. ACh release was inhibited by 5-HT1B agonists in hippocampal (not cortical) slices of WT but not of 5-HT1B KO mice. Our data (i) confirm the absence of autoinhibition of 5-HT release in 5-HT1B-KO mice, (ii) demonstrate a reduced release of ACh, and the absence of 5-HT1B-receptor-mediated inhibition of ACh release, in the hippocampus and cortex of 5-HT1B-KO mice, and (iii) are compatible with an indirect role of cortical ACh in the working memory impairment observed in these KO mice.
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Affiliation(s)
- Susanne Rutz
- Institute of Experimental and Clinical Pharmacology and Toxicology, Laboratory of Neuropharmacology, University of Freiburg, Hansastrasse 9A, D-79104 Freiburg, Germany
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Villalobos C, Beique JC, Gingrich JA, Andrade R. Serotonergic regulation of calcium-activated potassium currents in rodent prefrontal cortex. Eur J Neurosci 2006; 22:1120-6. [PMID: 16176353 DOI: 10.1111/j.1460-9568.2005.04307.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
In spite of a growing understanding of the actions of 5-hydroxytryptamine (5-HT) in the prefrontal cortex, the specific cellular mechanism used by 5-HT in this region remains poorly understood. Previous studies have shown that 5-HT inhibits the after hyper-polarization that follows a burst of spikes in pyramidal neurons. In the present study, we have used whole cell recordings in rat and mouse brain slices to re-examine this phenomenon with special emphasis on identifying the 5-HT receptor subtypes mediating this effect. Layer V pyramidal neurons display complex after hyper-polarizations that are mediated predominantly by calcium-activated potassium channels and involve two distinct currents known as medium after hyper-polarizating current and slow after hyper-polarizating current (I(sAHP)). Administration of 5-HT reduced the current underlying these after hyper-polarizations by selectively inhibiting I(sAHP). Pharmacological analysis of this response indicates that the main receptor responsible for this inhibition belongs to the 5-HT(2A) subtype. Thus, alpha-methyl-5-HT and 2,5-dimethoxy-4-bromoamphetamine (DOB) mimic the effect of 5-HT and the effect of these agonists is blocked by MDL 100 907. Similarly, administration of alpha-methyl-5-HT is without effect in slices derived from 5-HT(2A) receptor knockout mice. However, 5-HT(2A) receptor blockade only partially suppressed the ability of 5-HT to inhibit I(sAHP). This suggests the involvement of at least one more receptor subtype in this response. Consistent with this idea, administration of 5-carboxyamido-tryptamine, an agonist exhibiting no detectable affinity for 5-HT(2A) receptors, was also capable of suppressing I(sAHP). These results identify 5-HT(2A) receptors as being primarily involved in mediating the 5-HT-induced inhibition of I(sAHP) in prefrontal cortex, while also recognizing a contribution by an additional 5-HT receptor subtype.
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Affiliation(s)
- Claudio Villalobos
- Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine, Detroit, MI 48201, USA
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45
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Rios M, Lambe EK, Liu R, Teillon S, Liu J, Akbarian S, Roffler-Tarlov S, Jaenisch R, Aghajanian GK. Severe deficits in 5-HT2A-mediated neurotransmission in BDNF conditional mutant mice. ACTA ACUST UNITED AC 2006; 66:408-20. [PMID: 16408297 DOI: 10.1002/neu.20233] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
BDNF is thought to provide critical trophic support for serotonin neurons. In order to determine postnatal effects of BDNF on the serotonin system, we examined a line of conditional mutant mice that have normal brain content of BDNF during prenatal development but later depletion of this neurotrophin in the postnatal period. These mice show a behavioral phenotype that suggests serotonin dysregulation. However, as shown here, the presynaptic serotonin system in the adult conditional mutant mice appeared surprisingly normal from histological, biochemical, and electrophysiological perspectives. By contrast, a dramatic and unexpected postsynaptic 5-HT2A deficit in the mutant mice was found. Electrophysiologically, serotonin neurons appeared near normal except, most notably, for an almost complete absence of expected 5-HT2A -mediated glutamate and GABA postsynaptic potentials normally displayed by these neurons. Further analysis showed that BDNF mutants had much reduced 5-HT2A receptor protein in dorsal raphe nucleus and a similar deficit in prefrontal cortex, a region that normally shows a high level of 5-HT2A receptor expression. Recordings in prefrontal slice showed a marked deficit in 5-HT2A -mediated excitatory postsynaptic currents, similar to that seen in the dorsal raphe. These findings suggest that postnatal levels of BDNF play a relatively limited role in maintaining presynaptic aspects of the serotonin system and a much greater role in maintaining postsynaptic 5-HT2A and possibly other receptors than previously suspected.
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Affiliation(s)
- Maribel Rios
- Department of Neuroscience, Tufts University School of Medicine, Boston, Massachusetts 02111, USA.
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Monro RL, Bornstein JC, Bertrand PP. Slow excitatory post-synaptic potentials in myenteric AH neurons of the guinea-pig ileum are reduced by the 5-hydroxytryptamine7 receptor antagonist SB 269970. Neuroscience 2005; 134:975-86. [PMID: 16009503 DOI: 10.1016/j.neuroscience.2005.05.006] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2005] [Revised: 04/22/2005] [Accepted: 05/03/2005] [Indexed: 01/21/2023]
Abstract
Serotonin (5-HT) is a key modulator of neuronal excitability in the central and peripheral nervous system. In the enteric nervous system, 5-HT causes a slow depolarization in the intrinsic sensory neurons, but the receptor responsible for this has not been correlated with known gene products. The aim of this study was to determine whether the newly characterized 5-HT7 receptor may participate in the 5-HT-mediated depolarization of, and synaptic transmission to, the intrinsic sensory neurons of the guinea-pig ileum. Intracellular electrophysiological recordings were made from intrinsic sensory neurons identified as myenteric AH neurons from guinea-pig ileum. 5-HT (5 microM) applied to the cell body evoked both a fast depolarization (5-HT3 mediated) and/or a slow depolarization (5-HT1P-like). The 5-HT1/5/7 receptor agonist 5-carboxamidotryptamine (5-CT) (5 microM) evoked only a slow depolarization. When the fast depolarization evoked by 5-HT was blocked with granisetron (1 microM, 5-HT3 receptor antagonist), only a slow depolarization remained; this was abolished by the 5-HT7 receptor antagonist SB 269970 (1 microM, control: 14+/-2 mV, granisetron+SB 269970: -1+/-2 mV). The slow depolarization evoked by 5-CT was also significantly reduced by SB 269970 (control: 14+/-1 mV, SB 269970: 5+/-2 mV) suggesting a 5-HT7 receptor was activated by exogenous application of 5-CT and 5-HT. Slow excitatory postsynaptic potentials evoked by stimulating descending neural pathways (containing serotonergic fibers) were reduced by SB 269970 (control: 8+/-3 mV, SB 269970: 3+/-1 mV). However, SB 269970 had no effect on slow excitatory postsynaptic potentials evoked by stimulation of circumferential (tachykinergic) pathways (control: 7+/-1 mV, SB 269970: 6+/-1 mV). These data are consistent with the presence on enteric AH neurons of functional 5-HT7 receptors that participate in slow synaptic transmission.
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Affiliation(s)
- R L Monro
- Department of Physiology, University of Melbourne, Parkville 3010, Victoria, Australia.
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Yoshioka M, Togashi H, Yamaguchi T, Matsumoto M. [Emotional stress and functional development of the rat brain]. Nihon Yakurigaku Zasshi 2005; 125:77-82. [PMID: 15812136 DOI: 10.1254/fpj.125.77] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
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48
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Matsumoto M, Higuchi K, Togashi H, Koseki H, Yamaguchi T, Kanno M, Yoshioka M. Early postnatal stress alters the 5-HTergic modulation to emotional stress at postadolescent periods of rats. Hippocampus 2005; 15:775-81. [PMID: 15999341 DOI: 10.1002/hipo.20100] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Several lines of evidence have shown that traumatic events during the early postnatal stage might precipitate long-lasting alteration in the functional properties underlying emotional expression. The aim of the present study was to examine whether the early postnatal stress alters the 5-HTergic mechanism underlying regulation of emotional stress, focusing on the 5-HT(1A) receptor-mediated synaptic responses in adult rats. Pups were exposed to aversive stimulus, footshock (FS) at the postnatal period of the second (2W) and the third week (3W). At postadolescent period (10-12-week-old), electrophysiological and behavioral studies were performed. The 5-HT(1A) receptor agonist tandospirone (10 mg/kg body wt, i.p.) blocked the long-term potentiation (LTP) in the hippocampal CA1 field of 3W-FS, as well as non-FS control, whereas this inhibition was not observed in 2W-FS group. Fear-related freezing behavior observed during exposure to contextual fear conditioning markedly attenuated in 2W-FS, but not in 3W-FS. These data suggest that aversive stress exposed at 2W is attributable to changes in the 5-HT(1A) receptor-mediated synaptic plasticity, which may be responsible for the attenuation of freezing behavior. Thus, 5-HT(1A) receptors appear to play a key role in the 5-HTergic mechanism underlying regulation of emotional stress on the postnatal development of the brain. In other words, the second postnatal week may be the "critical period" for establishing proper behavioral responses to emotional stress in adult rats. (c) 2005 Wiley-Liss, Inc.
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Affiliation(s)
- Machiko Matsumoto
- Department of Neuropharmacology, Hokkaido University Graduate School of Medicine, Sapporo, Japan
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Béïque JC, Campbell B, Perring P, Hamblin MW, Walker P, Mladenovic L, Andrade R. Serotonergic regulation of membrane potential in developing rat prefrontal cortex: coordinated expression of 5-hydroxytryptamine (5-HT)1A, 5-HT2A, and 5-HT7 receptors. J Neurosci 2004; 24:4807-17. [PMID: 15152041 PMCID: PMC6729457 DOI: 10.1523/jneurosci.5113-03.2004] [Citation(s) in RCA: 151] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The developing prefrontal cortex receives a dense serotonergic innervation, yet little is known about the actions of serotonin [5-Hydroxytryptamine (5-HT)] in this region during development. Here, we examined the developmental regulation of 5-HT receptors controlling the excitability of pyramidal neurons of this region. Using whole-cell recordings in in vitro brain slices, we identified a dramatic shift in the effects of 5-HT on membrane potential during the postnatal developmental period. In slices derived from young animals [postnatal day (P) 6 to P19], administration of 5-HT elicits a robust depolarization of layer V pyramidal neurons, which gradually shifts to a hyperpolarization commencing during the third postnatal week. This progression is the result of coordinated changes in the function of 5-HT7 and 5-HT2A receptors, which mediate different aspects of the depolarization, and of 5-HT1A receptors, which signal the late developing hyperpolarization. The loss of the 5-HT7 receptor-mediated depolarization and the appearance of the 5-HT1A receptor-mediated hyperpolarization appears to reflect changes in receptor expression. In contrast, the decline in the 5-HT2A receptor depolarization with increasing age was associated with changes in the effectiveness with which these receptors could elicit a membrane depolarization, rather than loss of the receptors per se. Together, these results outline coordinated changes in the serotonergic regulation of cortical excitability at a time of extensive synaptic development and thus suggest a key role for these receptor subtypes in the postnatal development of the prefrontal cortex.
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MESH Headings
- Age Factors
- Animals
- G Protein-Coupled Inwardly-Rectifying Potassium Channels
- Gene Expression Regulation, Developmental/physiology
- In Situ Hybridization
- In Vitro Techniques
- Male
- Membrane Potentials/drug effects
- Membrane Potentials/physiology
- Neurons/drug effects
- Neurons/metabolism
- Patch-Clamp Techniques
- Potassium Channels/metabolism
- Potassium Channels, Inwardly Rectifying
- Prefrontal Cortex/drug effects
- Prefrontal Cortex/growth & development
- Prefrontal Cortex/metabolism
- Pyramidal Cells/drug effects
- Pyramidal Cells/metabolism
- RNA, Messenger/metabolism
- Rats
- Rats, Sprague-Dawley
- Receptor, Serotonin, 5-HT1A/biosynthesis
- Receptor, Serotonin, 5-HT1A/genetics
- Receptor, Serotonin, 5-HT2A/biosynthesis
- Receptor, Serotonin, 5-HT2A/genetics
- Receptors, Serotonin/biosynthesis
- Receptors, Serotonin/genetics
- Reverse Transcriptase Polymerase Chain Reaction
- Serotonin/pharmacology
- Serotonin/physiology
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Affiliation(s)
- Jean-Claude Béïque
- Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine, Detroit, Michigan 48201, USA.
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