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Quentin E, Belmer A, Maroteaux L. Somato-Dendritic Regulation of Raphe Serotonin Neurons; A Key to Antidepressant Action. Front Neurosci 2018; 12:982. [PMID: 30618598 PMCID: PMC6307465 DOI: 10.3389/fnins.2018.00982] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Accepted: 12/07/2018] [Indexed: 11/22/2022] Open
Abstract
Several lines of evidence implicate serotonin (5-hydroxytryptamine, 5-HT)in regulating personality traits and mood control. Serotonergic neurons are classically thought to be tonic regular-firing, “clock-like” neurons. Neurotransmission by serotonin is tightly regulated by the serotonin transporter (SERT) and by autoreceptors (serotonin receptors expressed by serotonin neurons) through negative feedback inhibition at the cell bodies and dendrites (5-HT1A receptors) of the dorsal raphe nuclei or at the axon terminals (5-HT1B receptors). In dorsal raphe neurons, the release of serotonin from vesicles in the soma, dendrites, and/or axonal varicosities is independent of classical synapses and can be induced by neuron depolarization, by the stimulation of L-type calcium channels, by activation of glutamatergic receptors, and/or by activation of 5-HT2 receptors. The resulting serotonin release displays a slow kinetic and a large diffusion. This process called volume transmission may ultimately affect the rate of discharge of serotonergic neurons, and their tonic activity. The therapeutic effects induced by serotonin-selective reuptake inhibitor (SSRI) antidepressants are initially triggered by blocking SERT but rely on consequences of chronic exposure, i.e., a selective desensitization of somatodendritic 5-HT1A autoreceptors. Agonist stimulation of 5-HT2B receptors mimicked behavioral and neurogenic SSRI actions, and increased extracellular serotonin in dorsal raphe. By contrast, a lack of effects of SSRIs was observed in the absence of 5-HT2B receptors (knockout-KO), even restricted to serotonergic neurons (Htr2b5-HTKO mice). The absence of 5-HT2B receptors in serotonergic neurons is associated with a higher 5-HT1A-autoreceptor reactivity and thus a lower firing activity of these neurons. In agreement, mice with overexpression of 5-HT1A autoreceptor show decreased neuronal activity and increased depression-like behavior that is resistant to SSRI treatment. We propose thus that the serotonergic tone results from the opposite control exerted by somatodendritic (Gi-coupled) 5-HT1A and (Gq-coupled) 5-HT2B receptors on dorsal raphe neurons. Therefore, 5-HT2B receptors may contribute to SSRI therapeutic effects by their positive regulation of adult raphe serotonergic neurons. Deciphering the molecular mechanism controlling extrasynaptic release of serotonin, and how autoreceptors interact in regulating the tonic activity of serotonergic neurons, is critical to fully understand the therapeutic effect of SSRIs.
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Affiliation(s)
- Emily Quentin
- INSERM UMR-S 839, Institut du Fer à Moulin, Paris, France.,Sorbonne Universités, UPMC University Paris 6, Paris, France.,Institut du Fer à Moulin, Paris, France
| | - Arnauld Belmer
- INSERM UMR-S 839, Institut du Fer à Moulin, Paris, France.,Sorbonne Universités, UPMC University Paris 6, Paris, France.,Institut du Fer à Moulin, Paris, France
| | - Luc Maroteaux
- INSERM UMR-S 839, Institut du Fer à Moulin, Paris, France.,Sorbonne Universités, UPMC University Paris 6, Paris, France.,Institut du Fer à Moulin, Paris, France
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2
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Belmer A, Quentin E, Diaz SL, Guiard BP, Fernandez SP, Doly S, Banas SM, Pitychoutis PM, Moutkine I, Muzerelle A, Tchenio A, Roumier A, Mameli M, Maroteaux L. Positive regulation of raphe serotonin neurons by serotonin 2B receptors. Neuropsychopharmacology 2018; 43:1623-1632. [PMID: 29453444 PMCID: PMC5983540 DOI: 10.1038/s41386-018-0013-0] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 01/10/2018] [Accepted: 01/17/2018] [Indexed: 01/03/2023]
Abstract
Serotonin is a neurotransmitter involved in many psychiatric diseases. In humans, a lack of 5-HT2B receptors is associated with serotonin-dependent phenotypes, including impulsivity and suicidality. A lack of 5-HT2B receptors in mice eliminates the effects of molecules that directly target serotonergic neurons including amphetamine derivative serotonin releasers, and selective serotonin reuptake inhibitor antidepressants. In this work, we tested the hypothesis that 5-HT2B receptors directly and positively regulate raphe serotonin neuron activity. By ex vivo electrophysiological recordings, we report that stimulation by the 5-HT2B receptor agonist, BW723C86, increased the firing frequency of serotonin Pet1-positive neurons. Viral overexpression of 5-HT2B receptors in these neurons increased their excitability. Furthermore, in vivo 5-HT2B-receptor stimulation by BW723C86 counteracted 5-HT1A autoreceptor-dependent reduction in firing rate and hypothermic response in wild-type mice. By a conditional genetic ablation that eliminates 5-HT2B receptor expression specifically and exclusively from Pet1-positive serotonin neurons (Htr2b 5-HTKO mice), we demonstrated that behavioral and sensitizing effects of MDMA (3,4-methylenedioxy-methamphetamine), as well as acute behavioral and chronic neurogenic effects of the antidepressant fluoxetine, require 5-HT2B receptor expression in serotonergic neurons. In Htr2b 5-HTKO mice, dorsal raphe serotonin neurons displayed a lower firing frequency compared to control Htr2b lox/lox mice as assessed by in vivo extracellular recordings and a stronger hypothermic effect of 5-HT1A-autoreceptor stimulation was observed. The increase in head-twitch response to DOI (2,5-dimethoxy-4-iodoamphetamine) further confirmed the lower serotonergic tone resulting from the absence of 5-HT2B receptors in serotonin neurons. Together, these observations indicate that the 5-HT2B receptor acts as a direct positive modulator of serotonin Pet1-positive neurons in an opposite way as the known 5-HT1A-negative autoreceptor.
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Affiliation(s)
- Arnauld Belmer
- 0000000121866389grid.7429.8INSERM UMR-S 839, 75005 Paris, France ,0000 0001 2308 1657grid.462844.8Sorbonne Universités, UPMC Univ Paris 6, 75005 Paris, France ,0000 0004 0520 8345grid.462192.aInstitut du Fer à Moulin, 75005 Paris, France ,0000000089150953grid.1024.7Translational Research Institute, Queensland University of Technology, Brisbane, QLD 4059 Australia
| | - Emily Quentin
- 0000000121866389grid.7429.8INSERM UMR-S 839, 75005 Paris, France ,0000 0001 2308 1657grid.462844.8Sorbonne Universités, UPMC Univ Paris 6, 75005 Paris, France ,0000 0004 0520 8345grid.462192.aInstitut du Fer à Moulin, 75005 Paris, France
| | - Silvina L. Diaz
- 0000000121866389grid.7429.8INSERM UMR-S 839, 75005 Paris, France ,0000 0001 2308 1657grid.462844.8Sorbonne Universités, UPMC Univ Paris 6, 75005 Paris, France ,0000 0004 0520 8345grid.462192.aInstitut du Fer à Moulin, 75005 Paris, France ,grid.441705.3Instituto de Biología Celular y Neurociencia, Fac. de Cs. Exactas, Químicas y Naturales, Universidad de Morón, UBA-CONICET – Paraguay 2155, 3° piso, C1121ABG Buenos Aires, Argentina
| | - Bruno P. Guiard
- Research Center on Animal Cognition, Center for Integrative Biology, 31062 Toulouse, France ,0000 0001 0723 035Xgrid.15781.3aUniversité Paul Sabatier, 31062 Toulouse, France ,UMR5169 CNRS, 31062 Toulouse, France
| | - Sebastian P. Fernandez
- 0000000121866389grid.7429.8INSERM UMR-S 839, 75005 Paris, France ,0000 0001 2308 1657grid.462844.8Sorbonne Universités, UPMC Univ Paris 6, 75005 Paris, France ,0000 0004 0520 8345grid.462192.aInstitut du Fer à Moulin, 75005 Paris, France ,0000 0004 0638 0649grid.429194.3IPMC – CNRS UMR7275 660 Route des Lucioles Sophia-Antipolis, 06560 Valbonne, France
| | - Stéphane Doly
- 0000000121866389grid.7429.8INSERM UMR-S 839, 75005 Paris, France ,0000 0001 2308 1657grid.462844.8Sorbonne Universités, UPMC Univ Paris 6, 75005 Paris, France ,0000 0004 0520 8345grid.462192.aInstitut du Fer à Moulin, 75005 Paris, France ,grid.503334.2Université Clermont Auvergne, INSERM, NEURO-DOL, 63000 Clermont-Ferrand, France
| | - Sophie M. Banas
- 0000000121866389grid.7429.8INSERM UMR-S 839, 75005 Paris, France ,0000 0001 2308 1657grid.462844.8Sorbonne Universités, UPMC Univ Paris 6, 75005 Paris, France ,0000 0004 0520 8345grid.462192.aInstitut du Fer à Moulin, 75005 Paris, France
| | - Pothitos M. Pitychoutis
- 0000000121866389grid.7429.8INSERM UMR-S 839, 75005 Paris, France ,0000 0001 2308 1657grid.462844.8Sorbonne Universités, UPMC Univ Paris 6, 75005 Paris, France ,0000 0004 0520 8345grid.462192.aInstitut du Fer à Moulin, 75005 Paris, France ,0000 0001 2175 167Xgrid.266231.2Department of Biology and Center for Tissue Regeneration and Engineering at Dayton (TREND), University of Dayton, Dayton, OH USA
| | - Imane Moutkine
- 0000000121866389grid.7429.8INSERM UMR-S 839, 75005 Paris, France ,0000 0001 2308 1657grid.462844.8Sorbonne Universités, UPMC Univ Paris 6, 75005 Paris, France ,0000 0004 0520 8345grid.462192.aInstitut du Fer à Moulin, 75005 Paris, France
| | - Aude Muzerelle
- 0000000121866389grid.7429.8INSERM UMR-S 839, 75005 Paris, France ,0000 0001 2308 1657grid.462844.8Sorbonne Universités, UPMC Univ Paris 6, 75005 Paris, France ,0000 0004 0520 8345grid.462192.aInstitut du Fer à Moulin, 75005 Paris, France
| | - Anna Tchenio
- 0000000121866389grid.7429.8INSERM UMR-S 839, 75005 Paris, France ,0000 0001 2308 1657grid.462844.8Sorbonne Universités, UPMC Univ Paris 6, 75005 Paris, France ,0000 0004 0520 8345grid.462192.aInstitut du Fer à Moulin, 75005 Paris, France ,0000 0001 2165 4204grid.9851.5Dept. Fundamental Neurosciences (DNF) The University of Lausanne, Lausanne, Switzerland
| | - Anne Roumier
- 0000000121866389grid.7429.8INSERM UMR-S 839, 75005 Paris, France ,0000 0001 2308 1657grid.462844.8Sorbonne Universités, UPMC Univ Paris 6, 75005 Paris, France ,0000 0004 0520 8345grid.462192.aInstitut du Fer à Moulin, 75005 Paris, France
| | - Manuel Mameli
- 0000000121866389grid.7429.8INSERM UMR-S 839, 75005 Paris, France ,0000 0001 2308 1657grid.462844.8Sorbonne Universités, UPMC Univ Paris 6, 75005 Paris, France ,0000 0004 0520 8345grid.462192.aInstitut du Fer à Moulin, 75005 Paris, France ,0000 0001 2165 4204grid.9851.5Dept. Fundamental Neurosciences (DNF) The University of Lausanne, Lausanne, Switzerland
| | - Luc Maroteaux
- INSERM UMR-S 839, 75005, Paris, France. .,Sorbonne Universités, UPMC Univ Paris 6, 75005, Paris, France. .,Institut du Fer à Moulin, 75005, Paris, France.
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Jeong HJ, Lam K, Mitchell VA, Vaughan CW. Serotonergic modulation of neuronal activity in rat midbrain periaqueductal gray. J Neurophysiol 2013; 109:2712-9. [DOI: 10.1152/jn.00790.2012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Serotonin (5-HT) modulates pain and anxiety from within the midbrain periaqueductal gray (PAG). In the present study, the effects of 5-HT- and 5-HT1/2 subtype-selective ligands on rat PAG neurons were examined using whole cell patch-clamp recordings in brain slices. In voltage clamp, 5-HT produced outward and inward currents in distinct subpopulations of neurons that varied throughout different subregions of the PAG. The 5-HT1A agonist R(+)-8-OH-DPAT (1 μM) produced outward currents in subpopulations of PAG neurons. By contrast, sumatriptan (1 μM) and other 5-HT1B, -D, and -F subtype agonists had little or no postsynaptic activity. The 5-HT2A/C agonists DOI (3 μM) and TCB-2 (1 μM) produced inward currents in subpopulations of PAG neurons, and DOI enhanced evoked inhibitory postsynaptic currents via a presynaptic mechanism. In current clamp, both R(+)-8-OH-DPAT and sumatriptan produced an excitatory increase in evoked mixed postsynaptic potentials (PSPs). In addition, R(+)-8-OH-DPAT, but not sumatriptan, directly hyperpolarized PAG neurons. By contrast, the 5-HT2 agonist DOI depolarized subpopulations of neurons and produced an inhibitory decrease in evoked mixed PSPs. These findings indicate that 5-HT1A and 5-HT1B/D ligands have partly overlapping inhibitory effects on membrane excitability and synaptic transmission within the PAG, which are functionally opposed by 5-HT2A/C actions in specific PAG subregions.
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Affiliation(s)
- Hyo-Jin Jeong
- Pain Management Research Institute, Kolling Institute of Medical Research, Northern Clinical School, The University of Sydney at Royal North Shore Hospital, St Leonards, New South Wales, Australia
| | - Karen Lam
- Pain Management Research Institute, Kolling Institute of Medical Research, Northern Clinical School, The University of Sydney at Royal North Shore Hospital, St Leonards, New South Wales, Australia
| | - Vanessa A. Mitchell
- Pain Management Research Institute, Kolling Institute of Medical Research, Northern Clinical School, The University of Sydney at Royal North Shore Hospital, St Leonards, New South Wales, Australia
| | - Christopher W. Vaughan
- Pain Management Research Institute, Kolling Institute of Medical Research, Northern Clinical School, The University of Sydney at Royal North Shore Hospital, St Leonards, New South Wales, Australia
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4
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Electrophysiological and pharmacological properties of GABAergic cells in the dorsal raphe nucleus. J Physiol Sci 2012; 63:147-54. [PMID: 23275149 PMCID: PMC3579464 DOI: 10.1007/s12576-012-0250-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Accepted: 12/15/2012] [Indexed: 02/06/2023]
Abstract
The dorsal raphe nucleus (DRN) is the origin of the central serotonin [5-hydroxytryptamine (5-HT)] system and plays an important role in the regulation of many physiological functions such as sleep/arousal, food intake and mood. In order to understand the regulatory mechanisms of 5-HT system, characterization of the types of neurons is necessary. We performed electrophysiological recordings in acute slices of glutamate decarboxylase 67-green fluorescent protein knock-in mice. We utilized this mouse to identify visually GABAergic cells. Especially, we examined postsynaptic responses mediated by 5-HT receptors between GABAergic and serotonergic cells in the DRN. Various current responses were elicited by 5-HT and 5-HT(1A) or 5-HT(2A/2C) receptor agonists in GABAergic cells. These results suggested that multiple 5-HT receptor subtypes overlap on GABAergic cells, and their combination might control 5-HT cells. Understanding the postsynaptic 5-HT feedback mechanisms may help to elucidate the 5-HT neurotransmitter system and develop novel therapeutic approaches.
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5
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Bach H, Arango V. Neuroanatomy of Serotonergic Abnormalities in Suicide. THE NEUROBIOLOGICAL BASIS OF SUICIDE 2012. [DOI: 10.1201/b12215-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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6
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Yamamoto R, Ueta Y, Sugai T, Kato N. A serotonergic discrimination favoring synaptic inputs that accompany robust spike firing in lateral amygdala neurons. Neuroscience 2012; 220:119-30. [PMID: 22698688 DOI: 10.1016/j.neuroscience.2012.06.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Revised: 05/30/2012] [Accepted: 06/04/2012] [Indexed: 11/26/2022]
Abstract
The amygdala and serotonergic innervations thereunto are considered to cooperatively modulate affective behaviors. By whole-cell recording, the present study examined effects of serotonin (5-HT) on synaptic transmission in the rat basolateral amygdala (BLA) complex, which is the amygdalar entrance for sensory information. Application of 5-HT-attenuated excitatory postsynaptic currents at synapses from the lateral amygdala (LA) to the BLA proper, and also at synapses from putative thalamic afferents to LA principal neurons, both depending on 5-HT(2) receptors. This reduction of synaptic responses was confirmed in the BLA under current clamp. In the LA, by contrast, synaptic potentials were not reduced, but enhanced by 5-HT. With 5-HT bath-applied, a prolonged depolarization was induced in LA neurons by strong synaptic stimulation, which appears similar to a slow after-depolarization (sADP) induced by injecting depolarizing currents. Occurrence of such current-induced sADP was confirmed in LA neurons. Both the synaptically-activated prolonged depolarization and the current-induced sADPs depended on 5-HT(2) receptor activation and postsynaptic calcium increase, suggesting that the same postsynaptic intrinsic mechanisms are involved. Reduction of potassium currents was identified as a major ionic mechanism for this sADPs. We thus revealed that 5-HT usually reduces overall synaptic transmission in the whole BLA complex, but enables sADPs to occur, thereby increasing synaptic responsiveness of LA neurons in a positive feedback manner. With this duality of 5-HT actions in operation, a weak input to the BLA complex would be usually eliminated, but could be selected were it associated with sufficiently large depolarization.
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Affiliation(s)
- R Yamamoto
- Department of Physiology, Kanazawa Medical University, Ishikawa 920-0293, Japan
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7
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Opioidergic, GABAergic and serotonergic neurotransmission in the dorsal raphe nucleus modulates tonic immobility in guinea pigs. Physiol Behav 2012; 106:109-16. [DOI: 10.1016/j.physbeh.2012.01.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Revised: 01/04/2012] [Accepted: 01/05/2012] [Indexed: 11/24/2022]
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Diaz SL, Doly S, Narboux-Nême N, Fernández S, Mazot P, Banas SM, Boutourlinsky K, Moutkine I, Belmer A, Roumier A, Maroteaux L. 5-HT(2B) receptors are required for serotonin-selective antidepressant actions. Mol Psychiatry 2012; 17:154-63. [PMID: 22158014 PMCID: PMC3381222 DOI: 10.1038/mp.2011.159] [Citation(s) in RCA: 127] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The therapeutic effects induced by serotonin-selective reuptake inhibitor (SSRI) antidepressants are initially triggered by blocking the serotonin transporter and rely on long-term adaptations of pre- and post-synaptic receptors. We show here that long-term behavioral and neurogenic SSRI effects are abolished after either genetic or pharmacological inactivation of 5-HT(2B) receptors. Conversely, direct agonist stimulation of 5-HT(2B) receptors induces an SSRI-like response in behavioral and neurogenic assays. Moreover, the observation that (i) this receptor is expressed by raphe serotonergic neurons, (ii) the SSRI-induced increase in hippocampal extracellular serotonin concentration is strongly reduced in the absence of functional 5-HT(2B) receptors and (iii) a selective 5-HT(2B) agonist mimics SSRI responses, supports a positive regulation of serotonergic neurons by 5-HT(2B) receptors. The 5-HT(2B) receptor appears, therefore, to positively modulate serotonergic activity and to be required for the therapeutic actions of SSRIs. Consequently, the 5-HT(2B) receptor should be considered as a new tractable target in the combat against depression.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | - Luc Maroteaux
- * Correspondence should be adressed to: Luc Maroteaux
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Kawai R, Kobayashi S, Fujito Y, Ito E. Multiple Subtypes of Serotonin Receptors in the Feeding Circuit of a Pond Snail. Zoolog Sci 2011; 28:517-25. [DOI: 10.2108/zsj.28.517] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Guo JD, Rainnie DG. Presynaptic 5-HT(1B) receptor-mediated serotonergic inhibition of glutamate transmission in the bed nucleus of the stria terminalis. Neuroscience 2009; 165:1390-401. [PMID: 19963045 DOI: 10.1016/j.neuroscience.2009.11.071] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2009] [Revised: 11/20/2009] [Accepted: 11/29/2009] [Indexed: 11/16/2022]
Abstract
Activation of neurons in the bed nucleus of the stria terminalis (BNST) plays a critical role in stress and anxiety-related behaviors. Previously, we have shown that serotonin (5-HT) can directly modulate BNST neuronal excitability by an action at postsynaptic receptors. In this study we built upon that work to examine the effects of 5-HT on excitatory neurotransmission in an in vitro rat BNST slice preparation. Bath application of 5-HT reversibly reduced the amplitude of evoked excitatory postsynaptic currents (eEPSCs). These effects were mimicked by the 5-HT(1B/D) receptor agonist, sumatriptan, and by the 5-HT(1B) receptor selective agonist, CP93129. Conversely, the effects of 5-HT and sumatriptan could be blocked by the 5-HT(1B) receptor-selective antagonist, GR55562. In contrast, the 5-HT(1A) receptor agonist 8-OH DPAT or antagonist WAY 100635 could not mimic or block the effect of 5-HT on eEPSCs. Together, these data suggest that the 5-HT-induced attenuation of eEPSCs was mediated by 5-HT(1B) receptor activation. Moreover, sumatriptan had no effect on the amplitude of the postsynaptic current elicited by pressure applied AMPA, suggesting a possible presynaptic locus for the 5-HT(1B) receptor. Furthermore, 5-HT, sumatriptan and CP93129 all increased the paired pulse ratio of eEPSCs while they concomitantly decreased the amplitude of eEPSCs, suggesting that these agonists act to reduce glutamate release probability at presynaptic locus. Consistent with this observation, sumatriptan decreased the frequency of miniature EPSCs, but had no effect on their amplitude. Taken together, these results suggest that 5-HT suppresses glutamatergic neurotransmission in the BNST by activating presynaptic 5-HT(1B) receptors to decrease glutamate release from presynaptic terminals. This study illustrates a new pathway by which the activity of BNST neurons can be indirectly modulated by 5-HT, and suggests a potential new target for the development of novel treatments for depression and anxiety disorders.
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Affiliation(s)
- J-D Guo
- Department of Psychiatry and Behavioral Sciences, Yerkes National Primate Research Center, Emory University, Atlanta, GA, USA
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11
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Bi-directional modulation of bed nucleus of stria terminalis neurons by 5-HT: molecular expression and functional properties of excitatory 5-HT receptor subtypes. Neuroscience 2009; 164:1776-93. [PMID: 19778589 DOI: 10.1016/j.neuroscience.2009.09.028] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2009] [Revised: 09/05/2009] [Accepted: 09/16/2009] [Indexed: 01/28/2023]
Abstract
Activation of neurons in the anterolateral bed nucleus of the stria terminalis (BNST(ALG)) plays an important role in mediating the behavioral response to stressful and anxiogenic stimuli. Application of 5-HT elicits complex postsynaptic responses in BNST(ALG) neurons, which includes (1) membrane hyperpolarization (5-HT(Hyp)), (2) hyperpolarization followed by depolarization (5-HT(Hyp-Dep)), (3) depolarization (5-HT(Dep)) or (4) no response (5-HT(NR)). We have shown that the inhibitory response is mediated by activation of postsynaptic 5-HT(1A) receptors. Here, we used a combination of in vitro whole-cell patch-clamp recording and single cell reverse transcriptase polymerase chain reaction (RT-PCR) to determine the pharmacological properties and molecular profile of 5-HT receptor subtypes mediating the excitatory response to 5-HT in BNST(ALG) neurons. We show that the depolarizing component of both the 5-HT(Hyp/Dep) and the 5-HT(Dep) response was mediated by activation of 5-HT(2A), 5-HT(2C) and/or 5-HT(7) receptors. Single cell RT-PCR data revealed that 5-HT(7) receptors (46%) and 5-HT(1A) receptors (41%) are the most prevalent receptor subtypes expressed in BNST(ALG) neurons. Moreover, 5-HT receptor subtypes are differentially expressed in type I-III BNST(ALG) neurons. Hence, 5-HT(2C) receptors are almost exclusively expressed by type III neurons, whereas 5-HT(7) receptors are expressed by type I and II neurons, but not type III neurons. Conversely, 5-HT(2A) receptors are found predominantly in type II neurons. Finally, bi-directional modulation of individual neurons occurs only in type I and II neurons. Significantly the distribution of 5-HT receptor subtypes in BNST(ALG) neurons predicted the observed expression pattern of 5-HT responses determined pharmacologically. Together, these results suggest that 5-HT can differentially modulate the excitability of type I-III neurons, and further suggest that bi-directional modulation of BNST(ALG) neurons occurs primarily through an interplay between 5-HT(1A) and 5-HT(7) receptors. Hence, modulation of 5-HT(7) receptor activity in the BNST(ALG) may offer a novel avenue for the design of anxiolytic medications.
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12
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Ma L, Shalinsky MH, Alonso A, Dickson CT. Effects of serotonin on the intrinsic membrane properties of layer II medial entorhinal cortex neurons. Hippocampus 2007; 17:114-29. [PMID: 17146777 DOI: 10.1002/hipo.20250] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Although serotonin (5-HT) is an important neuromodulator in the superficial layers of the medial entorhinal cortex (mEC), there is some disagreement concerning its influences upon the membrane properties of neurons within this region. We performed whole cell recordings of mEC Layer II projection neurons in rat brain slices in order to characterize the intrinsic influences of 5-HT. In current clamp, 5-HT evoked a biphasic response consisting of a moderately short latency and large amplitude hyperpolarization followed by a slowly developing, long lasting, and small amplitude depolarization. Correspondingly, in voltage clamp, 5-HT evoked a robust outward followed by a smaller inward shift of holding current. The outward current evoked by 5-HT showed a consistent current/voltage (I/V) relationship across cells with inward rectification, and demonstrating a reversal potential that was systematically dependent upon the extracellular concentration of K(+), suggesting that it was predominantly carried by potassium ions. However, the inward current showed a less consistent I/V relationship across different cells, suggesting multiple independent ionic mechanisms. The outward current was mediated through activation of 5-HT(1A) receptors via a G-protein dependent mechanism while inward currents were evoked in a 5-HT(1A)-independent fashion. A significant proportion of the inward current was blocked by the I(h) inhibitor ZD7288 and appeared to be due to 5-HT modulation of I(h) as 5-HT shifted the activation curve of I(h) in a depolarizing fashion. Serotonin is thus likely to influence, in a composite fashion, the information processing of Layer II neurons in the mEC and thus, the passage of neocortical information via the perforant pathway to the hippocampus.
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Affiliation(s)
- Li Ma
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
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13
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Loucif AJC, Bonnavion P, Macri B, Golmard JL, Boni C, Melfort M, Leonard G, Lesch KP, Adrien J, Jacquin TD. Gender-dependent regulation of G-protein-gated inwardly rectifying potassium current in dorsal raphe neurons in knock-out mice devoid of the 5-hydroxytryptamine transporter. ACTA ACUST UNITED AC 2007; 66:1475-88. [PMID: 17013926 DOI: 10.1002/neu.20321] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Agonists at G-protein-coupled receptors in neurons of the dorsal raphe nucleus (DRN) of knock-out mice devoid of the serotonin transporter (5-HTT(-/-)) exhibit lower efficacy to inhibit cellular discharge than in wild-type counterparts. Using patch-clamp whole-cell recordings, we found that a G-protein-gated inwardly rectifying potassium (GIRK) current is involved in the inhibition of spike discharge induced by 5-HT1A agonists (5-carboxamidotryptamine (5-CT) and (+/-)-2-dipropylamino-8-hydroxy-1,2,3,4-tetrahydronaphthalene hydrobromide (8-OH-DPAT); 50 nM-30 microM) in both wild-type and 5-HTT(-/-) female and male mice. These effects were mimicked by 5'-guanylyl-imido-diphosphate (Gpp(NH)p; 400 microM) dialysis into cells with differences between genders. The 5-HTT(-/-) knock-out mutation reduced the current density induced by Gpp(NH)p in females but not in males. These data suggest that the decreased response of 5-HT1A receptors to agonists in 5-HTT(-/-) mutants reflects notably alteration in the coupling between G-proteins and GIRK channels in females but not in males. Accordingly, gender differences in central 5-HT neurotransmission appear to depend-at least in part-on sex-related variations in corresponding receptor-G protein signaling mechanisms.
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Affiliation(s)
- Alexandre Julien Châu Loucif
- UMR 677, INSERM/UPMC, NeuroPsychoPharmacologie, Faculté de Médecine Pierre et Marie Curie, Site Pitié-Salpêtrière, 91 Boulevard de l'Hôpital, 75634 Paris Cedex 13, France
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Ago Y, Nakamura S, Kajita N, Uda M, Hashimoto H, Baba A, Matsuda T. Ritanserin reverses repeated methamphetamine-induced behavioral and neurochemical sensitization in mice. Synapse 2007; 61:757-63. [PMID: 17568413 DOI: 10.1002/syn.20421] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Chronic administration of methamphetamine (METH) elicits progressive enhancement of locomotor activity known as behavioral sensitization. We have recently shown that chronic METH enhanced METH challenge-induced increase in 5-HT levels in the prefrontal cortex and that 5-HT(1A) receptor activation attenuated this neurochemical sensitization as well as behavioral sensitization. This study examined whether the nonselective 5-HT(2) receptor antagonist, ritanserin affects METH-induced behavioral and neurochemical sensitization in mice. Ritanserin at doses of 1 and 3 mg/kg inhibited the development and expression of METH-induced behavioral sensitization in a dose-dependent manner. Furthermore, chronic administration of ritanserin for a week attenuated the maintenance of behavioral sensitization, indicating the improvement of established behavioral sensitization. Microdialysis analysis showed that chronic ritanserin inhibited the neurochemical sensitization that chronic METH enhanced METH challenge-induced increase in extracellular 5-HT levels in the prefrontal cortex. Furthermore, acute ritanserin inhibited METH challenge-induced increase in extracellular 5-HT but not DA levels in the prefrontal cortex. These results suggest that 5-HT(2) receptors are involved in METH-induced hyperactivity and behavioral sensitization in mice.
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Affiliation(s)
- Yukio Ago
- Laboratory of Medicinal Pharmacology, Graduate School of Pharmaceutical Sciences, Osaka University, Osaka 565-0871, Japan
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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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Lechin F, van der Dijs B, Hernández-Adrián G. Dorsal raphe vs. median raphe serotonergic antagonism. Anatomical, physiological, behavioral, neuroendocrinological, neuropharmacological and clinical evidences: relevance for neuropharmacological therapy. Prog Neuropsychopharmacol Biol Psychiatry 2006; 30:565-85. [PMID: 16436311 DOI: 10.1016/j.pnpbp.2005.11.025] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 11/30/2005] [Indexed: 01/28/2023]
Abstract
Monoaminergic neurons located in the central nervous system (CNS) are organized into complex circuits which include noradrenergic (NA), adrenergic (Ad), dopaminergic (DA), serotonergic (5-HT), histaminergic (H), GABA-ergic and glutamatergic systems. Most of these circuits are composed of more than one and often several types of the above neurons. Such physiologically flexible circuits respond appropriately to both external and internal stimuli which, if not modulated adequately, can trigger pathophysiologic responses. A great deal of research has been devoted to mapping the multiple functions of the CNS circuitry, thereby forming the basis for effective neuropharmacological therapeutic approaches. Such lineal strategies that seek to normalize complex and mixed physiological disorders, however, meet only partial therapeutic success and are often followed by undesirable side effects and/or total failure. In light of these, we have worked to develop possible models of CNS circuitry that are less affected by physiological interaction using the models to design more effective therapeutic approaches. In the present review, we cite and present evidence supporting the dorsal raphe versus median raphe serotonergic circuitry as one model of a reliable paradigm, necessary to the clear understanding and therapy of many psychiatric and even non-psychiatric disturbances.
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Affiliation(s)
- Fuad Lechin
- Department of Physiological Sciences, Section of Neurochemical, Instituto de Medicina Experimental, Universidad Central de Venezuela, Caracas, Venezuela.
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Judge SJ, Gartside SE. Firing of 5-HT neurones in the dorsal and median raphe nucleus in vitro shows differential alpha1-adrenoceptor and 5-HT1A receptor modulation. Neurochem Int 2005; 48:100-7. [PMID: 16256247 DOI: 10.1016/j.neuint.2005.09.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2005] [Accepted: 09/14/2005] [Indexed: 11/20/2022]
Abstract
The median raphe nucleus and dorsal raphe nucleus together are the major source of ascending 5-HT projections. Here, using in vitro extracellular single unit electrophysiology we examined the responses of individual neurones in the rat median raphe nucleus and dorsal raphe nucleus to alpha(1)-adrenoceptor and 5-HT(1A) receptor activation and made comparisons between the two nuclei. In the presence of the alpha(1)-adrenoceptor agonist phenylephrine (1microM) all spontaneously active neurones recorded in the median and dorsal raphe nuclei fired slowly (<5Hz) and regularly. Most were inhibited by 5-HT (10-50microM), although a few were excited by 5-HT. 5-HT-induced inhibition was attenuated by the 5-HT(1A) receptor antagonist, WAY100635 (100nM). Compared to those in the dorsal raphe nucleus, the neurones in the median raphe nucleus which were inhibited by 5-HT had: (1) lower basal firing rates in the continuous presence of phenylephrine (1microM), (2) smaller excitatory responses to higher concentrations of phenylephrine (3-10microM), (3) smaller excitatory responses to brief application of norepinephrine (10-100microM) and (4) smaller inhibitory responses to 5-HT (10-50microM). The lower sensitivity of median raphe neurones to alpha(1)-adrenoceptor excitation and 5-HT(1A) receptor inhibition will have consequences for 5-HT neurotransmission in forebrain regions innervated by the two nuclei.
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Affiliation(s)
- Sarah J Judge
- Psychobiology Research Group, School of Neurology, Neurobiology and Psychiatry, The Medical School, University of Newcastle upon Tyne, NE2 4HH, UK.
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Levita L, Hammack SE, Mania I, Li XY, Davis M, Rainnie DG. 5-hydroxytryptamine1A-like receptor activation in the bed nucleus of the stria terminalis: electrophysiological and behavioral studies. Neuroscience 2005; 128:583-96. [PMID: 15381287 DOI: 10.1016/j.neuroscience.2004.06.037] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/23/2004] [Indexed: 11/28/2022]
Abstract
The anteriorlateral bed nucleus of the stria terminalis (BNST AL) and the serotonergic system are believed to modulate behavioral responses to stressful and/or anxiogenic stimuli. However, although the BNST AL receives heavy serotonergic innervation, the functional significance of this input is not known. Data obtained from in vitro whole-cell patch clamp recording in the rat BNST slice show that exogenous application of 5-hydroxytryptamine (5-HT) evoked a heterogeneous response in BNST AL neurons. The principal action of 5-HT in this region was inhibitory, evoking a membrane hyperpolarization (5-HTHyp) and a concomitant reduction in input resistance in the majority of neurons tested. The broad-spectrum 5-HT1 agonist, 5-carboxamindotryptamine (5-CT), but not R(+/-)8-hydroxydipropylaminotetralin hydrobromide (8-OH-DPAT), mimicked the 5-HTHyp response in the BNST. Moreover, the outward current mediating 5-HTHyp was inwardly rectifying and sensitive to the G protein activated inwardly rectifying K+ (G IRK) channel blocker, tertiapin-Q. In the CNS 5-HT1A receptors are thought to couple to GIRK channels, suggesting that 5-HTHyp in BNST AL neurons was mediated by activation of 5-HT1A-like receptors. This was confirmed by the blockade of both 5-HTHyp and 5-CTHyp by the specific 5-HT1A receptor antagonist N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-2-pyridinylcyclohexanecarboxamide maleate salt (WAY100635 200nM). Furthermore, an in vivo examination of the functional consequences of 5-HT1A-like induced inhibition of BNST neurons revealed that infusion of 5-CT into the BNST significantly reduced the acoustic startle response, without affecting the general motor activity of the animals. These data point to the possibility that 5-HT1A mediated inhibition of the BNST AL could contribute to an anxiolytic action. Hence, we propose that in response to stressful stimuli, enhanced levels of 5-HT in the BNST AL plays a critical homeostatic role in feedback inhibition of the anxiogenic response to these stimuli.
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Affiliation(s)
- L Levita
- Department of Psychiatry and Behavioral Neuroscience, Emory University, Yerkes Neuroscience Building, 954 Gatewood Drive, Room 5220, Atlanta, GA 30322, USA
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Marinelli S, Schnell SA, Hack SP, Christie MJ, Wessendorf MW, Vaughan CW. Serotonergic and Nonserotonergic Dorsal Raphe Neurons Are Pharmacologically and Electrophysiologically Heterogeneous. J Neurophysiol 2004; 92:3532-7. [PMID: 15254076 DOI: 10.1152/jn.00437.2004] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The dorsal raphe nucleus (DRN) projects serotonergic axons throughout the brain and is involved in a variety of physiological functions. However, it also includes a large population of cells that contain other neurotransmitters. To clarify the physiological and pharmacological differences between the serotonergic and nonserotonergic neurons of the DRN, their postsynaptic responses to 5-hydroxytryptamine (5-HT, serotonin) and to selective activation of 5-HT1A or 5-HT2A/C receptors and their action potential characteristics were determined using in vitro patch-clamp recordings. The slices containing these neurons were then immunostained for tryptophan hydroxylase (TPH), a marker of serotonergic neurons. It was found that subpopulations of both serotonergic and nonserotonergic neurons responded to 5-HT with outward (i.e., inhibitory) and inward (i.e., excitatory) currents, responded to both 5-HT1A and 5-HT2A/C receptor activation with outward and inward currents, respectively, and displayed overlapping action potential characteristics. These findings suggest that serotonergic and nonserotonergic neurons in the DRN are both heterogeneous with respect to their individual pharmacological and electrophysiological characteristics. The findings also suggest that the activity of the different populations of DRN neurons will display heterogeneous changes when the serotonergic tone in the DRN is altered by neurological disorders or by drug treatment.
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Affiliation(s)
- Silvia Marinelli
- Pain Management Research Institute, Northern Clinical School, University of Sydney, New South Wales, 2006 Australia
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Manfridi A, Brambilla D, Bianchi S, Mariotti M, Opp MR, Imeri L. Interleukin-1beta enhances non-rapid eye movement sleep when microinjected into the dorsal raphe nucleus and inhibits serotonergic neurons in vitro. Eur J Neurosci 2003; 18:1041-9. [PMID: 12956704 DOI: 10.1046/j.1460-9568.2003.02836.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Interleukin-1 (IL-1) and IL-1 receptors are constitutively expressed in normal brain. IL-1 increases non-rapid eye movements (NREM) sleep in several animal species, an effect mediated in part by interactions with the serotonergic system. The site(s) in brain at which interactions between IL-1 and the serotonergic system increase NREM sleep remain to be identified. The dorsal raphe (DRN) is the origin of the major ascending serotonergic pathways to the forebrain, and it contains IL-1 receptors. This study examined the hypothesis that IL-1 increases NREM sleep by acting at the level of the DRN. IL-1beta (0.25 and 0.5 ng) was microinjected into the DRN of freely behaving rats and subsequent effects on sleep-wake activity were determined. IL-1beta 0.5 ng increased NREM sleep during the first 2 h post-injection from 33.5 +/- 3.7% after vehicle microinjection to 42.9 +/- 3.0% of recording time. To determine the effects of IL-1beta on electrophysiological properties of DRN serotonergic neurons, intracellular recordings were performed in a guinea-pig brain stem slice preparation. In 26 of 32 physiologically and pharmacologically identified serotonergic neurons, IL-1beta superfusion (25 ng/mL) decreased spontaneous firing rates by 50%, from 1.6 +/- 0.2 Hz (before IL-1beta superfusion) to 0.8 +/- 0.2 Hz. This effect was reversible upon washout. These results show that IL-1beta increases NREM sleep when administered directly into the DRN. Serotonin enhances wakefulness and these novel data also suggest that IL-1beta-induced enhancement of NREM sleep could be due in part to the inhibition of DRN serotonergic neurons.
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Affiliation(s)
- Alfredo Manfridi
- Institute of Human Physiology II, 'Giuseppe Moruzzi' Centre for Experimental Sleep Research, Milano, Italy
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