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Nagayasu K. Integrative Research of Neuropharmacology and Informatics Pharmacology for Mental Disorder. Biol Pharm Bull 2024; 47:556-561. [PMID: 38432911 DOI: 10.1248/bpb.b23-00926] [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] [Indexed: 03/05/2024]
Abstract
Mental illness poses a huge social burden, accounting for approximately 14% of all deaths. Depression, a major component of mental illness, affects approximately 300 million people worldwide, mainly in developed countries, and is not only a major social burden but also a cause of suicide. The social burden of depression is estimated to increase further in developing countries, and overcoming it is a pressing issue for all countries, including Japan. Although clinical evidence has demonstrated the efficacy of serotonergic neurotransmission enhancers in the treatment of depression, the full picture of their therapeutic effects has not yet been fully elucidated. In this review, we show that the hyperactivity of serotonin neurons, especially those in the dorsal raphe nucleus, is commonly induced by various antidepressants within a period corresponding to the onset of their clinical efficacy. We established quantitative prediction methods for pharmacological activity using only chemical structures to translate the biological understanding of mental disorders, including major depressive disorders, into clinically effective therapeutics. Our method exhibited better performance than the previously reported methods of quantitative prediction, while targeting a larger number of proteins. Our article suggests the importance of integrative neuropharmacology and informatics-based pharmacology studies to understand the biological basis of mental disorders and facilitate drug development for these disorders.
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Affiliation(s)
- Kazuki Nagayasu
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University
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2
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Dorsal raphe serotonergic neurons preferentially reactivate dorsal dentate gyrus cell ensembles associated with positive experience. Cell Rep 2023; 42:112149. [PMID: 36821440 DOI: 10.1016/j.celrep.2023.112149] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2022] [Revised: 11/24/2022] [Accepted: 02/06/2023] [Indexed: 02/24/2023] Open
Abstract
Major depressive disorder (MDD) is among the most common mental illnesses. Serotonergic (5-HT) neurons are central to the pathophysiology and treatment of MDD. Repeatedly recalling positive episodes is effective for MDD. Stimulating 5-HT neurons of the dorsal raphe nucleus (DRN) or neuronal ensembles in the dorsal dentate gyrus (dDG) associated with positive memories reverses the stress-induced behavioral abnormalities. Despite this phenotypic similarity, their causal relationship is unclear. This study revealed that the DRN 5-HT neurons activate dDG neurons; surprisingly, this activation was specifically observed in positive memory ensembles rather than neutral or negative ensembles. Furthermore, we revealed that dopaminergic signaling induced by activation of DRN 5-HT neurons projecting to the ventral tegmental area mediates an increase in active coping behavior and positive dDG ensemble reactivation. Our study identifies a role of DRN 5-HT neurons as specific reactivators of positive memories and provides insights into how serotonin elicits antidepressive effects.
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Meurer YDSR, Linhares SSG, Lima ADC, de Aquino ACQ, Brandão LEM, Nôga DA, Campelo CLDC, Lima RH, Cavalcante JDS, Engelberth RCGJ, Ribeiro AM, Silva RH. Postnatal exposure to fluoxetine led to cognitive-emotional alterations and decreased parvalbumin positive neurons in the hippocampus of juvenile Wistar rats. Int J Dev Neurosci 2021; 81:616-632. [PMID: 34196404 DOI: 10.1002/jdn.10139] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 05/29/2021] [Accepted: 06/24/2021] [Indexed: 12/31/2022] Open
Abstract
The exposure to selective serotonin reuptake inhibitors (SSRIs) during development results in behavioural impairment in adulthood in humans and animal models. Indeed, serotonergic overexpression in early life leads to structural and functional changes in brain circuits that control cognition and emotion. However, the effects of developmental exposure to these substances on the behaviour of adolescent rats are conflicting and remain poorly characterised. We performed a behavioural screening to investigate the effects of postnatal exposure to fluoxetine on memory and behaviours related to anxiety, anhedonia, and depression, as well we evaluate the parvalbumin expression in hippocampus of juvenile (~PND45) female and male rats. Fluoxetine (daily 20 mg/kg s.c. injections from PND7-PND21)- or vehicle-treated adolescent rats went through several behavioural tasks (from PND 38 to PND52) and were subject to transcardial perfusion and brain removal for immunohistochemical analysis (PND53). We found that postnatal exposure to fluoxetine increased anxiety- and depression-like behaviours in the open field and sucrose preference and forced swimming tests, respectively. In addition, this treatment induced working memory and short-term (but not long-term) recognition memory impairments, and reduced parvalbumin-positive interneurons in the hippocampus. In addition, the results revealed developmental sex-dependent effects of fluoxetine postnatal treatment on adolescent rats' behaviour. These outcomes indicate that affective disorders and mnemonic alterations caused by SSRIs perinatal exposure can be present at adolescence.
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Affiliation(s)
- Ywlliane da Silva Rodrigues Meurer
- Behavioral Neuroscience Laboratory, Department of Pharmacology, Federal University of São Paulo, São Paulo, Brazil.,Memory and Cognition Studies Laboratory, Post-graduate Program of Cognitive Neuroscience and Behavior, Department of Psychology, Federal University of Paraíba, João Pessoa, Brazil.,Laboratory of Neurochemical Studies, Department of Physiology and Behavior, Federal University of Rio Grande do Norte, Natal, Brazil
| | - Sara Sophia Guedes Linhares
- Laboratory of Neurochemical Studies, Department of Physiology and Behavior, Federal University of Rio Grande do Norte, Natal, Brazil
| | - Alvaro da Costa Lima
- Memory and Cognition Studies Laboratory, Post-graduate Program of Cognitive Neuroscience and Behavior, Department of Psychology, Federal University of Paraíba, João Pessoa, Brazil
| | - Antonio Carlos Queiroz de Aquino
- Laboratory of Neurochemical Studies, Department of Physiology and Behavior, Federal University of Rio Grande do Norte, Natal, Brazil
| | | | | | | | - Ramon Hypólito Lima
- Graduate Program in Neuroengineering, Edmond and Lily Safra International Institute of Neuroscience, Santos Dumont Institute, Macaíba, Brazil
| | - Jeferson de Souza Cavalcante
- Laboratory of Neurochemical Studies, Department of Physiology and Behavior, Federal University of Rio Grande do Norte, Natal, Brazil
| | | | - Alessandra Mussi Ribeiro
- Laboratory of Neuroscience and Bioprospecting of Natural Products, Department of Biosciences, Federal University of São Paulo, Santos, Brazil
| | - Regina Helena Silva
- Behavioral Neuroscience Laboratory, Department of Pharmacology, Federal University of São Paulo, São Paulo, Brazil
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Involvement of protein kinase C beta1-serotonin transporter system dysfunction in emotional behaviors in stressed mice. Neurochem Int 2020; 140:104826. [DOI: 10.1016/j.neuint.2020.104826] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 07/27/2020] [Accepted: 08/07/2020] [Indexed: 12/17/2022]
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Saiz-Bianco E, Urbanavicius J, Prunell G, Lagos P. Melanin-concentrating hormone does not modulate serotonin release in primary cultures of fetal raphe nucleus neurons. Neuropeptides 2019; 74:70-81. [PMID: 30642579 DOI: 10.1016/j.npep.2018.12.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 12/03/2018] [Accepted: 12/30/2018] [Indexed: 11/18/2022]
Abstract
Melanin-concentrating hormone (MCH) is a neuropeptide present in neurons located in the hypothalamus that densely innervate serotonergic cells in the dorsal raphe nucleus (DRN). MCH administration into the DRN induces a depressive-like effect through a serotonergic mechanism. To further understand the interaction between MCH and serotonin, we used primary cultured serotonergic neurons to evaluate the effect of MCH on serotonergic release and metabolism by HPLC-ED measurement of serotonin (5-HT) and 5-hydroxyindolacetic acid (5-HIAA) levels. We confirmed the presence of serotonergic neurons in the E14 rat rhombencephalon by immunohistochemistry and showed for the first time evidence of MCHergic fibers reaching the area. Cultures obtained from rhombencephalic tissue presented 2.2 ± 0.7% of serotonergic and 48.9 ± 5.4% of GABAergic neurons. Despite the low concentration of serotonergic neurons, we were able to measure basal cellular and extracellular levels of 5-HT and 5-HIAA without the addition of any serotonergic-enhancer drug. As expected, 5-HT release was calcium-dependent and induced by depolarization. 5-HT extracellular levels were significantly increased by incubation with serotonin reuptake inhibitors (citalopram and nortriptyline) and a monoamine-oxidase inhibitor (clorgyline), and were not significantly modified by a 5-HT1A autoreceptor agonist (8-OHDPAT). Even though serotonergic cells responded as expected to these pharmacological treatments, MCH did not induce significant modifications of 5-HT and 5-HIAA extracellular levels in the cultures. Despite this unexpected result, we consider that assessment of 5-HT and 5-HIAA levels in primary serotonergic cultures may be an adequate approach to study the effect of other drugs and modulators on serotonin release, uptake and turnover.
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Affiliation(s)
- Eugenia Saiz-Bianco
- Departamento de Fisiología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - Jessika Urbanavicius
- Departamento de Neurofarmacología Experimental, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, Uruguay
| | - Giselle Prunell
- Departamento de Neuroquímica, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, Uruguay.
| | - Patricia Lagos
- Departamento de Fisiología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay.
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Asaoka N, Nishitani N, Kinoshita H, Kawai H, Shibui N, Nagayasu K, Shirakawa H, Nakagawa T, Kaneko S. Chronic antidepressant potentiates spontaneous activity of dorsal raphe serotonergic neurons by decreasing GABA B receptor-mediated inhibition of L-type calcium channels. Sci Rep 2017; 7:13609. [PMID: 29051549 PMCID: PMC5648823 DOI: 10.1038/s41598-017-13599-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Accepted: 09/26/2017] [Indexed: 12/13/2022] Open
Abstract
Spontaneous activity of serotonergic neurons of the dorsal raphe nucleus (DRN) regulates mood and motivational state. Potentiation of serotonergic function is one of the therapeutic strategies for treatment of various psychiatric disorders, such as major depression, panic disorder and obsessive-compulsive disorder. However, the control mechanisms of the serotonergic firing activity are still unknown. In this study, we examined the control mechanisms for serotonergic spontaneous activity and effects of chronic antidepressant administration on these mechanisms by using modified ex vivo electrophysiological recording methods. Serotonergic neurons remained firing even in the absence of glutamatergic and GABAergic ionotropic inputs, while blockade of L-type voltage dependent Ca2+ channels (VDCCs) in serotonergic neurons decreased spontaneous firing activity. L-type VDCCs in serotonergic neurons received gamma-aminobutyric acid B (GABAB) receptor-mediated inhibition, which maintained serotonergic slow spontaneous firing activity. Chronic administration of an antidepressant, citalopram, disinhibited the serotonergic spontaneous firing activity by weakening the GABAB receptor-mediated inhibition of L-type VDCCs in serotonergic neurons. Our results provide a new mechanism underlying the spontaneous serotonergic activity and new insights into the mechanism of action of antidepressants.
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Affiliation(s)
- Nozomi Asaoka
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-Shimoadachi-cho, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Naoya Nishitani
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-Shimoadachi-cho, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Haruko Kinoshita
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-Shimoadachi-cho, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Hiroyuki Kawai
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-Shimoadachi-cho, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Norihiro Shibui
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-Shimoadachi-cho, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Kazuki Nagayasu
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-Shimoadachi-cho, Sakyo-ku, Kyoto, 606-8501, Japan.
| | - Hisashi Shirakawa
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-Shimoadachi-cho, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Takayuki Nakagawa
- Department of Clinical Pharmacology and Therapeutics, Kyoto University Hospital, 54 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto, 606-8507, Japan
| | - Shuji Kaneko
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-Shimoadachi-cho, Sakyo-ku, Kyoto, 606-8501, Japan.
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Nagayasu K. Elucidation of the Role of Dorsal Raphe Serotonergic Neurons in Mood Regulation Using Pharmacological and Viral Vector-based Approaches. YAKUGAKU ZASSHI 2017; 137:341-346. [PMID: 28250331 DOI: 10.1248/yakushi.16-00240] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Growing evidence indicates that serotonergic neurons play a crucial role in brain function and dysfunction, such as in major depressive disorder. However, the complexity of serotonergic projections severely hampers the elucidation of their precise mechanisms. Here we summarize our recent studies on the effects of ketamine and olanzapine, which have been reported to be effective in treatment-resistant depression, on dorsal raphe nucleus serotonergic neurons, using microdialysis, electrophysiology experiments, and slice cultures. Furthermore, we discuss the results of our recent approach using viral vectors, in particular, HIV-1 based lentiviral vectors.
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Affiliation(s)
- Kazuki Nagayasu
- iPS Cell-based Research Project on Brain Neuropharmacology and Toxicology, Laboratory of Molecular Neuropharmacology, Graduate School of Pharmaceutical Sciences, Osaka University
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Imoto Y, Kira T, Sukeno M, Nishitani N, Nagayasu K, Nakagawa T, Kaneko S, Kobayashi K, Segi-Nishida E. Role of the 5-HT4 receptor in chronic fluoxetine treatment-induced neurogenic activity and granule cell dematuration in the dentate gyrus. Mol Brain 2015; 8:29. [PMID: 25976618 PMCID: PMC4430984 DOI: 10.1186/s13041-015-0120-3] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Accepted: 04/24/2015] [Indexed: 11/30/2022] Open
Abstract
Background Chronic treatment with selective serotonin (5-HT) reuptake inhibitors (SSRIs) facilitates adult neurogenesis and reverses the state of maturation in mature granule cells (GCs) in the dentate gyrus (DG) of the hippocampus. Recent studies have suggested that the 5-HT4 receptor is involved in both effects. However, it is largely unknown how the 5-HT4 receptor mediates neurogenic effects in the DG and, how the neurogenic and dematuration effects of SSRIs interact with each other. Results We addressed these issues using 5-HT4 receptor knockout (5-HT4R KO) mice. Expression of the 5-HT4 receptor was detected in mature GCs but not in neuronal progenitors of the DG. We found that chronic treatment with the SSRI fluoxetine significantly increased cell proliferation and the number of doublecortin-positive cells in the DG of wild-type mice, but not in 5-HT4R KO mice. We then examined the correlation between the increased neurogenesis and the dematuration of GCs. As reported previously, reduced expression of calbindin in the DG, as an index of dematuration, by chronic fluoxetine treatment was observed in wild-type mice but not in 5-HT4R KO mice. The proliferative effect of fluoxetine was inversely correlated with the expression level of calbindin in the DG. The expression of neurogenic factors in the DG, such as brain derived neurotrophic factor (Bdnf), was also associated with the progression of dematuration. These results indicate that the neurogenic effects of fluoxetine in the DG are closely associated with the progression of dematuration of GCs. In contrast, the DG in which neurogenesis was impaired by irradiation still showed significant reduction of calbindin expression by chronic fluoxetine treatment, suggesting that dematuration of GCs by fluoxetine does not require adult neurogenesis in the DG. Conclusions We demonstrated that the 5-HT4 receptor plays an important role in fluoxetine-induced adult neurogenesis in the DG in addition to GC dematuration, and that these phenomena are closely associated. Our results suggest that 5-HT4 receptor-mediated phenotypic changes, including dematuration in mature GCs, underlie the neurogenic effect of SSRIs in the DG, providing new insight into the cellular mechanisms of the neurogenic actions of SSRIs in the hippocampus.
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Affiliation(s)
- Yuki Imoto
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences Kyoto University, Yoshida Shimoadachi-cho, Sakyo-ku, Kyoto, 606-8501, Japan.
| | - Toshihiko Kira
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences Kyoto University, Yoshida Shimoadachi-cho, Sakyo-ku, Kyoto, 606-8501, Japan.
| | - Mamiko Sukeno
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences Kyoto University, Yoshida Shimoadachi-cho, Sakyo-ku, Kyoto, 606-8501, Japan.
| | - Naoya Nishitani
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences Kyoto University, Yoshida Shimoadachi-cho, Sakyo-ku, Kyoto, 606-8501, Japan.
| | - Kazuki Nagayasu
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences Kyoto University, Yoshida Shimoadachi-cho, Sakyo-ku, Kyoto, 606-8501, Japan.
| | - Takayuki Nakagawa
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences Kyoto University, Yoshida Shimoadachi-cho, Sakyo-ku, Kyoto, 606-8501, Japan.
| | - Shuji Kaneko
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences Kyoto University, Yoshida Shimoadachi-cho, Sakyo-ku, Kyoto, 606-8501, Japan.
| | - Katsunori Kobayashi
- Department of Pharmacology, Graduate School of Medicine, Nippon Medical School, Sendagi, Bunkyo-ku, Tokyo, Japan. .,Japan Science and Technology Agency, Core Research for Evolutional Science and Technology, Saitama, 332-0012, Japan.
| | - Eri Segi-Nishida
- Department of Biological Science and Technology, Faculty of Industrial Science and Technology, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo, 125-8585, Japan.
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Asaoka N, Nagayasu K, Nishitani N, Yamashiro M, Shirakawa H, Nakagawa T, Kaneko S. Inhibition of histone deacetylases enhances the function of serotoninergic neurons in organotypic raphe slice cultures. Neurosci Lett 2015; 593:72-7. [PMID: 25796177 DOI: 10.1016/j.neulet.2015.03.028] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 03/10/2015] [Accepted: 03/16/2015] [Indexed: 10/23/2022]
Abstract
Inhibition of histone deacetylases (HDACs) is a promising approach for the treatment of mood disorders. However, the effects of HDAC inhibition on the serotonin (5-HT) system, a common target for psychiatric disorders, are poorly understood. Here, we show that a broad-spectrum HDAC inhibitor, trichostatin A (TSA), enhances the function of 5-HT neurons in organotypic raphe slice cultures. Sustained treatment with TSA (1μM) for 2 or 4 days significantly increased the 5-HT tissue content and tryptophan hydroxylase 2 (TPH2) expression, which were accompanied by hyper-acetylation of histone H3 in the promoter region of the TPH2 gene. TSA treatment for 4 days increased the extracellular 5-HT level, which was significantly suppressed in the presence of the selective AMPA receptor (AMPAR) antagonist NBQX. Moreover, the expression of both the AMPAR subunit GluA2 and Ca(2+)/calmodulin-dependent kinase II α (CaMKIIα) mRNAs were significantly increased by TSA treatment. Co-treatment with the CaMKII inhibitors KN-62 and KN-93 prevented the TSA-induced increase in 5-HT release, but had no effect on the increases in 5-HT tissue content. These results suggest that inhibition of HDACs increases 5-HT synthesis and release by epigenetic mechanisms, and that 5-HT release is mediated by the enhancement of AMPAR-mediated excitatory inputs and CaMKII signaling.
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Affiliation(s)
- Nozomi Asaoka
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
| | - Kazuki Nagayasu
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan; Drug Innovation Center, Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan; Laboratory of Molecular Neuropharmacology, Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan
| | - Naoya Nishitani
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
| | - Mayumi Yamashiro
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
| | - Hisashi Shirakawa
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
| | - Takayuki Nakagawa
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan; Department of Clinical Pharmacology and Therapeutics, Kyoto University Hospital, Kyoto, Japan.
| | - Shuji Kaneko
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
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Asaoka N, Nagayasu K, Nishitani N, Yamashiro M, Shirakawa H, Nakagawa T, Kaneko S. Olanzapine augments the effect of selective serotonin reuptake inhibitors by suppressing GABAergic inhibition via antagonism of 5-HT₆ receptors in the dorsal raphe nucleus. Neuropharmacology 2015; 95:261-8. [PMID: 25863120 DOI: 10.1016/j.neuropharm.2015.03.032] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Revised: 03/24/2015] [Accepted: 03/25/2015] [Indexed: 12/18/2022]
Abstract
The combination of the selective serotonin reuptake inhibitors (SSRIs) and atypical antipsychotic drugs shows better therapeutic efficacy than SSRI monotherapy in the treatment of depression. However, the underlying mechanisms responsible for the augmenting effects of olanzapine are not fully understood. Here, we report that olanzapine enhances the SSRI-induced increase in extracellular serotonin (5-HT) levels and antidepressant-like effects by inhibiting GABAergic neurons through 5-HT6 receptor antagonism in the dorsal raphe nucleus (DRN). In organotypic raphe slice cultures, treatment with olanzapine (1-100 μM) enhanced the increase in extracellular 5-HT levels in the presence of fluoxetine (10 μM) or citalopram (1 μM). The enhancing effect of olanzapine was not further augmented by the GABAA receptor antagonist bicuculline. Electrophysiological analysis revealed that olanzapine (50 μM) decreased the firing frequency of GABAergic neurons in acute DRN slices. Among many serotonergic agents, the 5-HT6 receptor antagonist SB399885 (1-100 μM) mimicked the effects of olanzapine by enhancing the SSRI-induced increase in extracellular 5-HT levels, which was not further augmented by bicuculline or olanzapine. SB399885 (50 μM) also decreased the firing frequency of GABAergic neurons in the DRN. In addition, an intraperitoneal administration of SB399885 (10 mg/kg) to mice significantly enhanced the antidepressant-like effect of a subeffective dose of citalopram (3 mg/kg) in the tail-suspension test. These results suggest that olanzapine decreases local inhibitory GABAergic tone in the DRN through antagonism of 5-HT6 receptors, thereby increasing the activity of at least part of serotonergic neurons, which may contribute to the augmentation of the efficacy of SSRIs.
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Affiliation(s)
- Nozomi Asaoka
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
| | - Kazuki Nagayasu
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan; Drug Innovation Center, Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan; Laboratory of Molecular Neuropharmacology, Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan
| | - Naoya Nishitani
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
| | - Mayumi Yamashiro
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
| | - Hisashi Shirakawa
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
| | - Takayuki Nakagawa
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan; Department of Clinical Pharmacology and Therapeutics, Kyoto University Hospital, Kyoto, Japan.
| | - Shuji Kaneko
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
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Raphe AMPA receptors and nicotinic acetylcholine receptors mediate ketamine-induced serotonin release in the rat prefrontal cortex. Int J Neuropsychopharmacol 2014; 17:1321-6. [PMID: 24852262 DOI: 10.1017/s1461145714000649] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Several lines of evidence indicate that ketamine has a rapid antidepressant-like effect in rodents and humans, but underlying mechanisms are unclear. In the present study, we investigated the effect of ketamine on serotonin (5-HT) release in the rat prefrontal cortex by in vivo microdialysis. A subcutaneous administration of ketamine (5 and 25 mg/kg) significantly increased the prefrontal 5-HT level in a dose-dependent manner, which was attenuated by local injection of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) antagonists into the dorsal raphe nucleus (DRN). Direct stimulation of AMPARs in the DRN significantly increased prefrontal 5-HT level, while intra-DRN injection of ketamine (36.5 nmol) had no effect. Furthermore, intra-DRN injection of an α 4 β 2-nicotinic acetylcholine receptor (nAChR) antagonist, dihydro-β-erythroidine (10 nmol), significantly attenuated the subcutaneous ketamine-induced increase in prefrontal 5-HT levels. These results suggest that AMPARs and α 4 β 2-nAChRs in the DRN play a key role in the ketamine-induced 5-HT release in the prefrontal cortex.
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Chronic effects of antidepressants on serotonin release in rat raphe slice cultures: high potency of milnacipran in the augmentation of serotonin release. Int J Neuropsychopharmacol 2013; 16:2295-306. [PMID: 23920436 DOI: 10.1017/s1461145713000771] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Most clinically-used antidepressants acutely increase monoamine levels in synaptic clefts, while their therapeutic effects often require several weeks of administration. Slow neuroadaptive changes in serotonergic neurons are considered to underlie this delayed onset of beneficial actions. Recently, we reported that sustained exposure of rat organotypic raphe slice cultures containing abundant serotonergic neurons to selective serotonin (5-HT) reuptake inhibitors (citalopram, fluoxetine and paroxetine) caused the augmentation of exocytotic serotonin release. However, the ability of other classes of antidepressants to evoke a similar outcome has not been clarified. In this study, we investigated the sustained actions of two tricyclic antidepressants (imipramine and desipramine), one tetracyclic antidepressant (mianserin), three 5-HT and noradrenaline reuptake inhibitors (milnacipran, duloxetine and venlafaxine) and one noradrenergic and specific serotonergic antidepressant (mirtazapine) on serotonin release in the slice cultures. For seven of nine antidepressants, sustained exposure to the agents at concentrations of 0.1-100 μ m augmented the level of increase in extracellular serotonin. The rank order of their potency was as follows: milnacipran>duloxetine>citalopram>venlafaxine>imipramine>fluoxetine>desipramine. Neither mirtazapine nor mianserin caused any augmentation. The highest augmentation by sustained exposure to milnacipran was partially attenuated by an α 1-adrenoceptor antagonist, benoxathian, while the duloxetine-, venlafaxine- and citalopram-mediated increases were not affected. These results suggest that inhibition of the 5-HT transporter is required for the enhancement of serotonin release. Furthermore, the potent augmentation by milnacipran is apparently due to the accompanied activation of the α 1-adrenoceptor.
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Peripheral and spinal 5-HT receptors participate in the pronociceptive and antinociceptive effects of fluoxetine in rats. Neuroscience 2013; 252:396-409. [DOI: 10.1016/j.neuroscience.2013.08.022] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Revised: 08/03/2013] [Accepted: 08/15/2013] [Indexed: 01/13/2023]
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Yang D, Chen M, Russo-Neustadt A. Antidepressants are neuroprotective against nutrient deprivation stress in rat hippocampal neurons. Eur J Neurosci 2012; 36:2573-87. [DOI: 10.1111/j.1460-9568.2012.08187.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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