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Jaster AM, González-Maeso J. Mechanisms and molecular targets surrounding the potential therapeutic effects of psychedelics. Mol Psychiatry 2023; 28:3595-3612. [PMID: 37759040 DOI: 10.1038/s41380-023-02274-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Accepted: 09/13/2023] [Indexed: 09/29/2023]
Abstract
Psychedelics, also known as classical hallucinogens, have been investigated for decades due to their potential therapeutic effects in the treatment of neuropsychiatric and substance use disorders. The results from clinical trials have shown promise for the use of psychedelics to alleviate symptoms of depression and anxiety, as well as to promote substantial decreases in the use of nicotine and alcohol. While these studies provide compelling evidence for the powerful subjective experience and prolonged therapeutic adaptations, the underlying molecular reasons for these robust and clinically meaningful improvements are still poorly understood. Preclinical studies assessing the targets and circuitry of the post-acute effects of classical psychedelics are ongoing. Current literature is split between a serotonin 5-HT2A receptor (5-HT2AR)-dependent or -independent signaling pathway, as researchers are attempting to harness the mechanisms behind the sustained post-acute therapeutically relevant effects. A combination of molecular, behavioral, and genetic techniques in neuropharmacology has begun to show promise for elucidating these mechanisms. As the field progresses, increasing evidence points towards the importance of the subjective experience induced by psychedelic-assisted therapy, but without further cross validation between clinical and preclinical research, the why behind the experience and its translational validity may be lost.
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Affiliation(s)
- Alaina M Jaster
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298, USA
- Department of Pharmacology and Toxicology, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298, USA
| | - Javier González-Maeso
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298, USA.
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2
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Song J, Kambari Y, Amaev A, Ueno F, Torres Carmona E, De Luca V, Pollock B, Flint A, Ishrat Husain M, Graff-Guerrero A, Gerretsen P. Psilocybin to promote synaptogenesis in the brains of patients with mild cognitive impairment. Med Hypotheses 2023. [DOI: 10.1016/j.mehy.2023.111068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/08/2023]
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3
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Aqil M, Roseman L. More than meets the eye: The role of sensory dimensions in psychedelic brain dynamics, experience, and therapeutics. Neuropharmacology 2023; 223:109300. [PMID: 36334767 DOI: 10.1016/j.neuropharm.2022.109300] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 10/08/2022] [Accepted: 10/20/2022] [Indexed: 11/11/2022]
Abstract
Psychedelics are undergoing a major resurgence of scientific and clinical interest. While multiple theories and frameworks have been proposed, there is yet no universal agreement on the mechanisms underlying the complex effects of psychedelics on subjective experience and brain dynamics, nor their therapeutic benefits. Despite being prominent in psychedelic phenomenology and distinct from those elicited by other classes of hallucinogens, the effects of psychedelics on low-level sensory - particularly visual - dimensions of experience, and corresponding brain dynamics, have often been disregarded by contemporary research as 'epiphenomenal byproducts'. Here, we review available evidence from neuroimaging, pharmacology, questionnaires, and clinical studies; we propose extensions to existing models, provide testable hypotheses for the potential therapeutic roles of psychedelic-induced visual hallucinations, and simulations of visual phenomena relying on low-level cortical dynamics. In sum, we show that psychedelic-induced alterations in low-level sensory dimensions 1) are unlikely to be entirely causally reconducible to high-level alterations, but rather co-occur with them in a dialogical interplay, and 2) are likely to play a causally relevant role in determining high-level alterations and therapeutic outcomes. We conclude that reevaluating the currently underappreciated role of sensory dimensions in psychedelic states will be highly valuable for neuroscience and clinical practice, and that integrating low-level and domain-specific aspects of psychedelic effects into existing nonspecific models is a necessary step to further understand how these substances effect both acute and long-term change in the human brain.
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Affiliation(s)
- Marco Aqil
- Spinoza Centre for Neuroimaging, the Netherlands; Computational Cognitive Neuroscience and Neuroimaging, Institute for Neuroscience, the Netherlands; Experimental and Applied Psychology, Vrije University Amsterdam, the Netherlands.
| | - Leor Roseman
- Centre for Psychedelic Research, Imperial College London, London, United Kingdom
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4
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Fu H, Rong J, Chen Z, Zhou J, Collier T, Liang SH. Positron Emission Tomography (PET) Imaging Tracers for Serotonin Receptors. J Med Chem 2022; 65:10755-10808. [PMID: 35939391 DOI: 10.1021/acs.jmedchem.2c00633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Serotonin (5-hydroxytryptamine, 5-HT) and 5-HT receptors (5-HTRs) have crucial roles in various neuropsychiatric disorders and neurodegenerative diseases, making them attractive diagnostic and therapeutic targets. Positron emission tomography (PET) is a noninvasive nuclear molecular imaging technique and is an essential tool in clinical diagnosis and drug discovery. In this context, numerous PET ligands have been developed for "visualizing" 5-HTRs in the brain and translated into human use to study disease mechanisms and/or support drug development. Herein, we present a comprehensive repertoire of 5-HTR PET ligands by focusing on their chemotypes and performance in PET imaging studies. Furthermore, this Perspective summarizes recent 5-HTR-focused drug discovery, including biased agonists and allosteric modulators, which would stimulate the development of more potent and subtype-selective 5-HTR PET ligands and thus further our understanding of 5-HTR biology.
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Affiliation(s)
- Hualong Fu
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Jian Rong
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114, United States.,Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Zhen Chen
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, International Innovation Center for Forest Chemicals and Materials, College of Chemical Engineering, Nanjing Forestry University, Nanjing, Jiangsu 210037, China
| | - Jingyin Zhou
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Thomas Collier
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114, United States.,Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Steven H Liang
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114, United States.,Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115, United States
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5
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Vohra HZ, Saunders JM, Jaster AM, de la Fuente Revenga M, Jimenez J, Fernández-Teruel A, Wolstenholme JT, Beardsley PM, González-Maeso J. Sex-specific effects of psychedelics on prepulse inhibition of startle in 129S6/SvEv mice. Psychopharmacology (Berl) 2022; 239:1649-1664. [PMID: 34345931 PMCID: PMC10103008 DOI: 10.1007/s00213-021-05913-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 06/22/2021] [Indexed: 01/04/2023]
Abstract
BACKGROUND Prepulse inhibition (PPI) of startle is a sensorimotor gating phenomenon perturbed in a variety of neuropsychiatric conditions. Psychedelics disrupt PPI in rats and humans, but their effects and involvement of the serotonin 5-HT2A receptor (5-HT2AR) in mice remain unexplored. METHODS We tested the effect of the psychedelic 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI) (0.5 mg/kg, i.p.) on startle amplitude and %PPI in response to acoustic stimuli under up to four different experimental conditions that included changes in background and stimulus intensity, prepulse and pulse duration, and interstimulus interval in male and female 129S6/SvEv mice. We also evaluated the effect of the 5-HT2AR antagonist M100,907 (1 mg/kg, i.p.) on DOI-induced startle amplitude and %PPI, as well as the effect of the psychedelic LSD (0.24 mg/kg, i.p.) and the dopamine agonists apomorphine (5 mg/kg, s.c.) and SKF-82,958 (0.5 mg/kg, i.p.) in male 129S6/SvEv mice. RESULTS DOI altered startle amplitude with either pulse alone or prepulse + pulse presentations in all PPI conditions, and increased %PPI in three out of four PPI conditions in male mice - an effect that was prevented by M100,907. In female mice, DOI increased %PPI without affecting startle amplitude. %PPI was positively correlated with startle amplitude in males while being negatively correlated in female mice. In male mice, LSD also increased %PPI, although it did not affect startle amplitude, whereas apomorphine and SKF-82,958 induced decreases in %PPI. CONCLUSION Our findings highlight a distinct effect of the psychedelic DOI on PPI in 129S6/SvEv mice, suggesting 5-HT2AR-dependent PPI improvement in a paradigm-dependent and sex-dependent manner.
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Affiliation(s)
- Hiba Z Vohra
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298, USA
| | - Justin M Saunders
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298, USA
| | - Alaina M Jaster
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298, USA.,Department of Pharmacology and Toxicology, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298, USA
| | - Mario de la Fuente Revenga
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298, USA.,Virginia Institute of Psychiatric and Behavioral Genetics, Virginia Commonwealth University, Richmond, VA, 23298, USA
| | - Jennifer Jimenez
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298, USA
| | - Alberto Fernández-Teruel
- Medical Psychology Unit, Department of Psychiatry and Forensic Medicine, Institute of Neurosciences, School of Medicine, Universidad Autónoma de Barcelona, E-08193, Bellaterra, Barcelona, Spain
| | - Jennifer T Wolstenholme
- Department of Pharmacology and Toxicology, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298, USA.,VCU Alcohol Research Center, Virginia Commonwealth University, Richmond, VA, 23298, USA
| | - Patrick M Beardsley
- Department of Pharmacology and Toxicology, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298, USA.,Center for Biomarker Research and Precision Medicine, Virginia Commonwealth University, Richmond, VA, 23298, USA
| | - Javier González-Maeso
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298, USA.
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Mangeant R, Dubost E, Cailly T, Collot V. Radiotracers for the Central Serotoninergic System. Pharmaceuticals (Basel) 2022; 15:ph15050571. [PMID: 35631397 PMCID: PMC9143978 DOI: 10.3390/ph15050571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 04/27/2022] [Accepted: 04/28/2022] [Indexed: 12/10/2022] Open
Abstract
This review lists the most important radiotracers described so far for imaging the central serotoninergic system. Single-photon emission computed tomography and positron emission tomography radiotracers are reviewed and critically discussed for each receptor.
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Affiliation(s)
- Reynald Mangeant
- Centre d’Etudes et de Recherche sur le Médicament de Normandie (CERMN), UNICAEN, Normandie Univ., 14000 Caen, France; (R.M.); (E.D.)
- Institut Blood and Brain @ Caen Normandie (BB@C), Boulevard Henri Becquerel, 14000 Caen, France
| | - Emmanuelle Dubost
- Centre d’Etudes et de Recherche sur le Médicament de Normandie (CERMN), UNICAEN, Normandie Univ., 14000 Caen, France; (R.M.); (E.D.)
- Institut Blood and Brain @ Caen Normandie (BB@C), Boulevard Henri Becquerel, 14000 Caen, France
| | - Thomas Cailly
- Centre d’Etudes et de Recherche sur le Médicament de Normandie (CERMN), UNICAEN, Normandie Univ., 14000 Caen, France; (R.M.); (E.D.)
- Institut Blood and Brain @ Caen Normandie (BB@C), Boulevard Henri Becquerel, 14000 Caen, France
- UNICAEN, IMOGERE, Normandie Univ., 14000 Caen, France
- CHU Côte de Nacre, Department of Nuclear Medicine, 14000 Caen, France
- Correspondence: (T.C.); (V.C.)
| | - Valérie Collot
- Centre d’Etudes et de Recherche sur le Médicament de Normandie (CERMN), UNICAEN, Normandie Univ., 14000 Caen, France; (R.M.); (E.D.)
- Institut Blood and Brain @ Caen Normandie (BB@C), Boulevard Henri Becquerel, 14000 Caen, France
- Correspondence: (T.C.); (V.C.)
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7
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Sierra S, Muchhala KH, Jessup DK, Contreras KM, Shah UH, Stevens DL, Jimenez J, Cuno Lavilla XK, de la Fuente Revenga M, Lippold KM, Shen S, Poklis JL, Qiao LY, Dewey WL, Akbarali HI, Damaj MI, González-Maeso J. Sex-specific role for serotonin 5-HT 2A receptor in modulation of opioid-induced antinociception and reward in mice. Neuropharmacology 2022; 209:108988. [PMID: 35183539 PMCID: PMC8934299 DOI: 10.1016/j.neuropharm.2022.108988] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 01/24/2022] [Accepted: 02/07/2022] [Indexed: 12/12/2022]
Abstract
Opioids are among the most effective analgesics and the mainstay of pain management. However, concerns about safety and abuse liability have challenged their widespread use by the medical community. Opioid-sparing therapies include drugs that in combination with opioids have the ability to enhance analgesia while decreasing opioid requirement as well as their side effects. Sex differences in antinociceptive responses to opioids have received increasing attention in recent years. However, the molecular mechanisms underlying sex differences related to opioid-sparing adjuncts remain largely unexplored. Using warm water tail-withdrawal as a mouse model of acute thermal nociception, our data suggest that adjunctive administration of the serotonin 5-HT2A receptor (5-HT2AR) antagonist volinanserin dose-dependently enhanced potency of the opioid analgesic oxycodone in male, but not female, mice. This antinociceptive-like response induced by oxycodone was also augmented in 5-HT2AR knockout (5-HT2AR-/-) male, but not female mice; an effect that was reversed by Cre-loxP-mediated selective expression of 5-HT2AR in dorsal root ganglion (DRG) neurons of 5-HT2AR-/- littermates. Pharmacological inhibition with volinanserin or genetic deletion in 5-HT2AR-/- animals potentiated the ability of oxycodone to reduce DRG excitability in male mice. Adjunctive volinanserin did not affect oxycodone-induced conditioned place preference (CPP), whereas it reduced oxycodone-induced locomotor sensitization in male and female mice. Together, these results suggest that adjunctive volinanserin augments opioid-induced antinociception, but not abuse-related behavior, through a sex-specific signaling crosstalk mechanism that requires 5-HT2AR expression in mouse DRG neurons. Ultimately, our results may pave the way for the clinical evaluation of volinanserin as a potential sex-specific opioid adjuvant.
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Affiliation(s)
- Salvador Sierra
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298, USA
| | - Karan H Muchhala
- Department of Pharmacology and Toxicology, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298, USA
| | - Donald K Jessup
- Department of Pharmacology and Toxicology, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298, USA
| | - Katherine M Contreras
- Department of Pharmacology and Toxicology, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298, USA
| | - Urjita H Shah
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298, USA
| | - David L Stevens
- Department of Pharmacology and Toxicology, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298, USA
| | - Jennifer Jimenez
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298, USA
| | - Xiomara K Cuno Lavilla
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298, USA
| | - Mario de la Fuente Revenga
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298, USA; Virginia Institute of Psychiatric and Behavioral Genetics, Virginia Commonwealth University, Richmond, VA, 23298, USA
| | - Kumiko M Lippold
- Department of Pharmacology and Toxicology, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298, USA
| | - Shanwei Shen
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298, USA
| | - Justin L Poklis
- Department of Pharmacology and Toxicology, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298, USA
| | - Liya Y Qiao
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298, USA
| | - William L Dewey
- Department of Pharmacology and Toxicology, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298, USA
| | - Hamid I Akbarali
- Department of Pharmacology and Toxicology, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298, USA
| | - M Imad Damaj
- Department of Pharmacology and Toxicology, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298, USA
| | - Javier González-Maeso
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298, USA.
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8
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Barrett FS, Zhou Y, Carbonaro TM, Roberts JM, Smith GS, Griffiths RR, Wong DF. Human Cortical Serotonin 2A Receptor Occupancy by Psilocybin Measured Using [ 11C]MDL 100,907 Dynamic PET and a Resting-State fMRI-Based Brain Parcellation. FRONTIERS IN NEUROERGONOMICS 2022; 2:784576. [PMID: 38235248 PMCID: PMC10790884 DOI: 10.3389/fnrgo.2021.784576] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 12/29/2021] [Indexed: 01/19/2024]
Abstract
Psilocybin (a serotonin 2A, or 5-HT2A, receptor agonist) has shown preliminary efficacy as a treatment for mood and substance use disorders. The current report utilized positron emission tomography (PET) with the selective 5-HT2A receptor inverse agonist radioligand [11C]MDL 100,907 (a.k.a. M100,907) and cortical regions of interest (ROIs) derived from resting-state functional connectivity-based brain parcellations in 4 healthy volunteers (2 females) to determine regional occupancy/target engagement of 5-HT2A receptors after oral administration of a psychoactive dose of psilocybin (10 mg/70 kg). Average 5-HT2A receptor occupancy across all ROIs was 39.5% (± 10.9% SD). Three of the ROIs with greatest occupancy (between 63.12 and 74.72% occupancy) were within the default mode network (subgenual anterior cingulate and bilateral angular gyri). However, marked individual variability in regional occupancy was observed across individuals. These data support further investigation of the relationship between individual differences in the acute and enduring effects of psilocybin and the degree of regional 5-HT2A receptor occupancy.
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Affiliation(s)
- Frederick S. Barrett
- Center for Psychedelic and Consciousness Research, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, United States
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Yun Zhou
- United Imaging Intelligence, Shanghai, China
| | - Theresa M. Carbonaro
- Center for Psychedelic and Consciousness Research, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Joshua M. Roberts
- Center for Psychedelic and Consciousness Research, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Gwenn S. Smith
- Division of Geriatric Psychiatry and Neuropsychiatry, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, United States
- Division of Nuclear Medicine and Molecular Imaging, Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Roland R. Griffiths
- Center for Psychedelic and Consciousness Research, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, United States
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Dean F. Wong
- Departments of Radiology, Psychiatry, Neurology, and Neuroscience, Mallinckrodt Institute of Radiology, Washington University in St Louis, St. Louis, MO, United States
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De Deurwaerdère P, Bharatiya R, Chagraoui A, Di Giovanni G. Constitutive activity of 5-HT receptors: Factual analysis. Neuropharmacology 2020; 168:107967. [DOI: 10.1016/j.neuropharm.2020.107967] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 12/26/2019] [Accepted: 01/12/2020] [Indexed: 12/16/2022]
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10
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Jensen AA, Halberstadt AL, Märcher-Rørsted E, Odland AU, Chatha M, Speth N, Liebscher G, Hansen M, Bräuner-Osborne H, Palner M, Andreasen JT, Kristensen JL. The selective 5-HT 2A receptor agonist 25CN-NBOH: Structure-activity relationship, in vivo pharmacology, and in vitro and ex vivo binding characteristics of [ 3H]25CN-NBOH. Biochem Pharmacol 2020; 177:113979. [PMID: 32298690 DOI: 10.1016/j.bcp.2020.113979] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Accepted: 04/10/2020] [Indexed: 01/16/2023]
Abstract
The remarkable effects exhibited by classical psychedelics in recent clinical trials have spawned considerable interest in 5-HT2A receptor (5-HT2AR) activation as a treatment strategy for several psychiatric/cognitive disorders. In this study we have continued our development of 25CN-NBOH, one of the most 5-HT2AR-selective agonists reported to date, as a pharmacological tool for exploration of 5-HT2AR expression and functions. The importance of the 2' and 3' positions in 25CN-NBOH as structural hotspots for its 5-HT2AR activity was investigated by synthesis and pharmacological characterization of six novel analogs at 5-HT2AR and 5-HT2CR in binding and functional assays. While the 5-HT2AR activity of 25CN-NBOH was retained in 3'-methyl, 2',3'-chroman, 2',3'-dihydrofuran and 2',3'-furan analogs, the 3'-methoxy and 3'-ethyl analogs displayed substantially lower binding affinities and agonist potencies than 25CN-NBOH. Interestingly, the 2',3'-substitution pattern was also a key determinant of agonist efficacy, as all six analogs exhibited low-efficacy partial agonism or de facto antagonism at the 5-HT2AR in the functional assays. Systemic administration of 25CN-NBOH and its close structural analog 25CN-NBMD induced robust head-twitch response in mice, a well-established behavioural effect of 5-HT2AR activation in vivo, and 25CN-NBOH mediated robust reductions in the activity of mice in an anxiety-related marble burying assay, which supports the proposed beneficial effects of 5-HT2AR activation on disorders characterized by cognitive rigidity. Finally, tritiated 25CN-NBOH exhibited high 5-HT2AR binding affinity (KD ~1 nM) and selectivity against 5-HT2BR and 5-HT2CR in equilibrium and kinetic binding studies of the recombinant receptors, and in concordance [3H]25CN-NBOH displayed substantial specific, ketanserin-sensitive binding to cortex and small levels of binding to choroid plexus in rat brain slices in autoradiography studies. In conclusion, this work delineates the subtle molecular determinants of the 5-HT2AR activity in 25CN-NBOH, substantiates the potential in this compound and its analogs as tools for in vivo studies of the 5-HT2AR, and introduces a novel selective agonist radioligand as another potentially valuable tool for future explorations of this receptor.
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Affiliation(s)
- Anders A Jensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen Ø, Denmark.
| | - Adam L Halberstadt
- Department of Psychiatry, University of California San Diego, La Jolla, CA, United States; Research Service, VA San Diego Healthcare System, La Jolla, CA, United States
| | - Emil Märcher-Rørsted
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen Ø, Denmark
| | - Anna U Odland
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen Ø, Denmark
| | - Muhammad Chatha
- Department of Psychiatry, University of California San Diego, La Jolla, CA, United States
| | - Nikolaj Speth
- Neurobiology Research Unit, Copenhagen University Hospital, Copenhagen, Denmark
| | - Gudrun Liebscher
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen Ø, Denmark
| | - Martin Hansen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen Ø, Denmark
| | - Hans Bräuner-Osborne
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen Ø, Denmark
| | - Mikael Palner
- Neurobiology Research Unit, Copenhagen University Hospital, Copenhagen, Denmark; Center for Translational Neuromedicine, University of Copenhagen, Copenhagen, Denmark
| | - Jesper T Andreasen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen Ø, Denmark
| | - Jesper L Kristensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen Ø, Denmark
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11
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L'Estrade ET, Erlandsson M, Edgar FG, Ohlsson T, Knudsen GM, Herth MM. Towards selective CNS PET imaging of the 5-HT 7 receptor system: Past, present and future. Neuropharmacology 2019; 172:107830. [PMID: 31669129 DOI: 10.1016/j.neuropharm.2019.107830] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2019] [Revised: 09/24/2019] [Accepted: 10/23/2019] [Indexed: 11/25/2022]
Abstract
Since its discovery in 1993, the serotonin receptor subtype 7 (5-HT7) has attracted significant attention as a potential drug target; due to its elucidated roles in conditions such as insomnia, schizophrenia, and more. Therefore, it is unsurprising that there has been relatively early efforts undertaken to develop a positron emission tomography (PET) imaging agent for said receptor system. PET can be clinically used to probe receptor systems in vivo, permitting information such as a drug's occupancy against this system to be investigated. This review focuses on the efforts towards the development of a 5-HT7R selective PET CNS tracer over the last 20 years, critically reflecting on applied strategies and commonly employed chemical frameworks and suggests future considerations that are needed to successfully develop a PET tracer for this clinically relevant target. This article is part of the special issue entitled 'Serotonin Research: Crossing Scales and Boundaries'.
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Affiliation(s)
- Elina T L'Estrade
- Neurobiology Research Unit, Rigshospitalet, Blegdamsvej 9, 2100, Copenhagen, Denmark; Department for Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetesparken 2, 2100, Copenhagen, Denmark; Radiation Physics, Nuclear Medicine Physics Unit, Skånes University Hospital, Barngatan 3, 222 42, Lund, Sweden
| | - Maria Erlandsson
- Radiation Physics, Nuclear Medicine Physics Unit, Skånes University Hospital, Barngatan 3, 222 42, Lund, Sweden
| | - Fraser G Edgar
- Department for Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetesparken 2, 2100, Copenhagen, Denmark
| | - Tomas Ohlsson
- Radiation Physics, Nuclear Medicine Physics Unit, Skånes University Hospital, Barngatan 3, 222 42, Lund, Sweden
| | - Gitte M Knudsen
- Neurobiology Research Unit, Rigshospitalet, Blegdamsvej 9, 2100, Copenhagen, Denmark; Institute of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Matthias M Herth
- Neurobiology Research Unit, Rigshospitalet, Blegdamsvej 9, 2100, Copenhagen, Denmark; Department for Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetesparken 2, 2100, Copenhagen, Denmark; Department of Clinical Physiology, Nuclear Medicine and PET, University Hospital Copenhagen, Rigshospitalet, Blegdamsvej 9, 2100, Copenhagen, Denmark.
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12
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Canal CE. Serotonergic Psychedelics: Experimental Approaches for Assessing Mechanisms of Action. Handb Exp Pharmacol 2019; 252:227-260. [PMID: 29532180 PMCID: PMC6136989 DOI: 10.1007/164_2018_107] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Recent, well-controlled - albeit small-scale - clinical trials show that serotonergic psychedelics, including psilocybin and lysergic acid diethylamide, possess great promise for treating psychiatric disorders, including treatment-resistant depression. Additionally, fresh results from a deluge of clinical neuroimaging studies are unveiling the dynamic effects of serotonergic psychedelics on functional activity within, and connectivity across, discrete neural systems. These observations have led to testable hypotheses regarding neural processing mechanisms that contribute to psychedelic effects and therapeutic benefits. Despite these advances and a plethora of preclinical and clinical observations supporting a central role for brain serotonin 5-HT2A receptors in producing serotonergic psychedelic effects, lingering and new questions about mechanisms abound. These chiefly pertain to molecular neuropharmacology. This chapter is devoted to illuminating and discussing such questions in the context of preclinical experimental approaches for studying mechanisms of action of serotonergic psychedelics, classic and new.
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Affiliation(s)
- Clinton E Canal
- Department of Pharmaceutical Sciences, College of Pharmacy, Mercer University, Atlanta, GA, USA.
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13
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Delicata F, Bombardi C, Pierucci M, Di Maio R, De Deurwaerdère P, Di Giovanni G. Preferential modulation of the lateral habenula activity by serotonin-2A rather than -2C receptors: Electrophysiological and neuroanatomical evidence. CNS Neurosci Ther 2018; 24:721-733. [PMID: 29479825 DOI: 10.1111/cns.12830] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 01/31/2018] [Accepted: 02/01/2018] [Indexed: 02/06/2023] Open
Abstract
AIMS Serotonergic (5-HT) modulation of the lateral habenula (LHb) activity is central in normal and pathologic conditions such as mood disorders. Among the multiple 5-HT receptors (5-HTRs) involved, the 5-HT2C R seems to play a pivotal role. Yet, the role of 5-HT2A Rs in the control of the LHb neuronal activity is completely unknown. METHODS Single-cell extracellular recording of the LHb neurons was used in rats to study the effect of the general activation and blockade of the 5-HT2C R and 5-HT2A R with Ro 60-0175 and SB242084, TCB-2 and MDL11939, respectively. The expression of both receptors in the LHb was confirmed using immunohistochemistry. RESULTS Cumulative doses (5-640 μg/kg, iv) of Ro 60-0175 and TCB-2 affected the activity of 34% and 63% of the LHb recorded neurons, respectively. LHb neurons were either inhibited at low doses or excited at higher doses of the 5-HT2A/C R agonists. SB242084 or MDL11939 (both at 200 μg/kg, iv) did not modify neuronal firing when injected alone, but reverted the bidirectional effects of Ro 60-0175 or TCB-2, respectively. 5-HT2C Rs and 5-HT2A Rs are expressed in less than the 20% of the LHb neurons, and they neither colocalize nor make heterodimers. Strikingly, only 5-HT2A Rs are expressed by the majority of LHb astrocyte cells. CONCLUSIONS Peripheral administration of 5-HT2A R agonist promotes a heterogeneous pattern of neuronal responses in the LHb, and these effects are more prominent than those induced by the 5-HT2C R activation.
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Affiliation(s)
- Francis Delicata
- Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Msida, Malta
| | - Cristiano Bombardi
- Dipartimento di Scienze Mediche Veterinarie, Università di Bologna, Bologna, Italia
| | - Massimo Pierucci
- Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Msida, Malta
| | - Roberto Di Maio
- Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh, Pittsburgh, PA, USA.,Department of Neurology, University of Pittsburgh, Pittsburgh, PA, USA.,Ri.MED Foundation, Palermo, Italy
| | - Philippe De Deurwaerdère
- Centre National de la Recherche Scientifique (Unité Mixte de Recherche 5287), Bordeaux Cedex, France
| | - Giuseppe Di Giovanni
- Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Msida, Malta.,School of Biosciences, Cardiff University, Cardiff, UK
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14
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Hazari PP, Pandey A, Chaturvedi S, Mishra AK. New Trends and Current Status of Positron-Emission Tomography and Single-Photon-Emission Computerized Tomography Radioligands for Neuronal Serotonin Receptors and Serotonin Transporter. Bioconjug Chem 2017; 28:2647-2672. [PMID: 28767225 DOI: 10.1021/acs.bioconjchem.7b00243] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The critical role of serotonin (5-hydroxytryptamine; 5-HT) and its receptors (5-HTRs) in the pathophysiology of diverse neuropsychiatric and neurodegenerative disorders render them attractive diagnostic and therapeutic targets for brain disorders. Therefore, the in vivo assessment of binding of 5-HT receptor ligands under a multitude of physiologic and pathologic scenarios may support more-accurate identification of disease and its progression and the patient's response to therapy as well as the screening of novel therapeutic strategies. The present Review aims to focus on the current status of radioligands used for positron-emission tomography (PET) and single-photon-emission computerized tomography (SPECT) imaging of human brain serotonin receptors. We further elaborate upon and emphasize the attributes that qualify a radioligand for theranostics on the basis of its frequency of use in clinics, its benefit to risk assessment in humans, and its continuous evolution, along with the major limitations.
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Affiliation(s)
- Puja Panwar Hazari
- Division of Cyclotron and Radiopharmaceutical Sciences, Institute of Nuclear Medicine and Allied Sciences , Brig S.K. Mazumdar Road, Delhi 110054, India
| | - Ankita Pandey
- Division of Cyclotron and Radiopharmaceutical Sciences, Institute of Nuclear Medicine and Allied Sciences , Brig S.K. Mazumdar Road, Delhi 110054, India
| | - Shubhra Chaturvedi
- Division of Cyclotron and Radiopharmaceutical Sciences, Institute of Nuclear Medicine and Allied Sciences , Brig S.K. Mazumdar Road, Delhi 110054, India
| | - Anil Kumar Mishra
- Division of Cyclotron and Radiopharmaceutical Sciences, Institute of Nuclear Medicine and Allied Sciences , Brig S.K. Mazumdar Road, Delhi 110054, India
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15
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Thentu JB, Nirogi R, Bhyrapuneni G, Ajjala DR, Aleti RR, Palacharla RC. Simultaneous in-vivo receptor occupancy assays for serotonin 1A, 2A, and dopamine 2 receptors with the use of non-radiolabelled tracers: Proposed method in screening antipsychotics. J Pharmacol Toxicol Methods 2017; 85:22-28. [DOI: 10.1016/j.vascn.2017.01.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Revised: 12/29/2016] [Accepted: 01/03/2017] [Indexed: 01/16/2023]
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Abstract
The neuropsychological effects of naturally occurring psychoactive chemicals have been recognized for millennia. Hallucinogens, which include naturally occurring chemicals such as mescaline and psilocybin, as well as synthetic compounds, such as lysergic acid diethylamide (LSD), induce profound alterations of human consciousness, emotion, and cognition. The discovery of the hallucinogenic effects of LSD and the observations that LSD and the endogenous ligand serotonin share chemical and pharmacological profiles led to the suggestion that biogenic amines like serotonin were involved in the psychosis of mental disorders such as schizophrenia. Although they bind other G protein-coupled receptor (GPCR) subtypes, studies indicate that several effects of hallucinogens involve agonist activity at the serotonin 5-HT2A receptor. In this chapter, we review recent advances in understanding hallucinogen drug action through characterization of structure, neuroanatomical location, and function of the 5-HT2A receptor.
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17
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Aznar S, Hervig MES. The 5-HT2A serotonin receptor in executive function: Implications for neuropsychiatric and neurodegenerative diseases. Neurosci Biobehav Rev 2016; 64:63-82. [DOI: 10.1016/j.neubiorev.2016.02.008] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 11/05/2015] [Accepted: 02/08/2016] [Indexed: 02/07/2023]
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18
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Zhang G, Stackman RW. The role of serotonin 5-HT2A receptors in memory and cognition. Front Pharmacol 2015; 6:225. [PMID: 26500553 PMCID: PMC4594018 DOI: 10.3389/fphar.2015.00225] [Citation(s) in RCA: 178] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 09/22/2015] [Indexed: 01/31/2023] Open
Abstract
Serotonin 5-HT2A receptors (5-HT2ARs) are widely distributed in the central nervous system, especially in brain region essential for learning and cognition. In addition to endogenous 5-HT, several hallucinogens, antipsychotics, and antidepressants function by targeting 5-HT2ARs. Preclinical studies show that 5-HT2AR antagonists have antipsychotic and antidepressant properties, whereas agonist ligands possess cognition-enhancing and hallucinogenic properties. Abnormal 5-HT2AR activity is associated with a number of psychiatric disorders and conditions, including depression, schizophrenia, and drug addiction. In addition to its traditional activity as a G protein-coupled receptor (GPCR), recent studies have defined novel operations of 5-HT2ARs. Here we review progress in the (1) receptor anatomy and biology: distribution, signaling, polymerization and allosteric modulation; and (2) receptor functions: learning and memory, hallucination and spatial cognition, and mental disorders. Based on the recent progress in basic research on the 5-HT2AR, it appears that post-training 5-HT2AR activation enhances non-spatial memory consolidation, while pre-training 5-HT2AR activation facilitates fear extinction. Further, the potential influence that 5-HT2AR-elicited visual hallucinations may have on visual cue (i.e., landmark) guided spatial cognition is discussed. We conclude that the development of selective 5-HT2AR modulators to target distinct signaling pathways and neural circuits represents a new possibility for treating emotional, neuropsychiatric, and neurodegenerative disorders.
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Affiliation(s)
- Gongliang Zhang
- College of Basic Medicine, Anhui Medical University Hefei, China ; Department of Biology, Charles E. Schmidt College of Science, Florida Atlantic University, Jupiter FL, USA ; Jupiter Life Science Initiative, Florida Atlantic University, Jupiter FL, USA
| | - Robert W Stackman
- Jupiter Life Science Initiative, Florida Atlantic University, Jupiter FL, USA ; Department of Psychology, Charles E. Schmidt College of Science, Florida Atlantic University, Jupiter FL, USA
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19
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Mengod G, Palacios JM, Cortés R. Cartography of 5-HT1A and 5-HT2A Receptor Subtypes in Prefrontal Cortex and Its Projections. ACS Chem Neurosci 2015; 6:1089-98. [PMID: 25739427 DOI: 10.1021/acschemneuro.5b00023] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Since the development of chemical neuroanatomical tools in the 1960s, a tremendous wealth of information has been generated on the anatomical components of the serotonergic system, at the microscopic level in the brain including the prefrontal cortex (PFC). The PFC receives a widespread distribution of serotonin (5-hydroxytryptamine, 5-HT) terminals from the median and dorsal raphe nuclei. 5-HT receptors were first visualized using radioligand autoradiography in the late 1980s and early 1990s and showed, in contrast to 5-HT innervation, a differential distribution of binding sites associated with different 5-HT receptor subtypes. Due to the cloning of the different 5-HT receptor subtype genes in the late 1980s and early 1990s, it was possible, using in situ hybridization histochemistry, to localize cells expressing mRNA for these receptors. Double in situ hybridization histochemistry and immunohistochemistry allowed for the chemical characterization of the phenotype of cells expressing 5-HT receptors. Tract tracing technology allowed a detailed cartography of the neuronal connections of PFC and other brain areas. Based on these data, maps have been constructed that reflect our current understanding of the different circuits where 5-HT receptors can modulate the electrophysiological, pharmacological, and behavioral functions of the PFC. We will review current knowledge regarding the cellular localization of 5-HT1A and 5-HT2A receptors in mammalian PFC and their possible functions in the neuronal circuits of the PFC. We will discuss data generated in our laboratory as well as in others, focusing on localization in the pyramidal and GABAergic neuronal cell populations in different mammalian species using molecular neuroanatomy and on the connections with other brain regions.
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Affiliation(s)
- Guadalupe Mengod
- Department
of
Neurochemistry and Neuropharmacology, IIBB-CSIC, IDIBAPS, CIBERNED, Barcelona 08036, Spain
| | | | - Roser Cortés
- Department
of
Neurochemistry and Neuropharmacology, IIBB-CSIC, IDIBAPS, CIBERNED, Barcelona 08036, Spain
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20
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Herth MM, Knudsen GM. Current radiosynthesis strategies for 5-HT2Areceptor PET tracers. J Labelled Comp Radiopharm 2015; 58:265-73. [DOI: 10.1002/jlcr.3288] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Revised: 03/10/2015] [Accepted: 03/16/2015] [Indexed: 11/12/2022]
Affiliation(s)
- Matthias M. Herth
- Center for Integrated Molecular Brain Imaging; Rigshospitalet and University of Copenhagen; Blegdamsvej 9 Copenhagen DK-2100 Denmark
- Department of Drug Design and Pharmacology; University of Copenhagen; Jagtvej 160 Copenhagen DK-2100 Denmark
| | - Gitte M. Knudsen
- Center for Integrated Molecular Brain Imaging; Rigshospitalet and University of Copenhagen; Blegdamsvej 9 Copenhagen DK-2100 Denmark
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21
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Visser AK, Ettrup A, Klein AB, van Waarde A, Bosker FJ, Meerlo P, Knudsen GM, de Boer SF. Similar serotonin-2A receptor binding in rats with different coping styles or levels of aggression. Synapse 2015; 69:226-32. [DOI: 10.1002/syn.21810] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 02/03/2015] [Accepted: 02/07/2015] [Indexed: 11/07/2022]
Affiliation(s)
- Anniek K.D. Visser
- Department of Nuclear Medicine and Molecular Imaging; University of Groningen, University Medical Center Groningen; Groningen The Netherlands
| | - Anders Ettrup
- Neurobiology Research Unit, Rigshospitalet and University of Copenhagen; Copenhagen Denmark
| | - Anders B. Klein
- Neurobiology Research Unit, Rigshospitalet and University of Copenhagen; Copenhagen Denmark
| | - Aren van Waarde
- Department of Nuclear Medicine and Molecular Imaging; University of Groningen, University Medical Center Groningen; Groningen The Netherlands
| | - Fokko J. Bosker
- Department of General Psychiatry, University Center of Psychiatry, University of Groningen, University Medical Center Groningen; Groningen The Netherlands
| | - Peter Meerlo
- Department of Behavioral Physiology; Center for Behavior and Neurosciences, University of Groningen; Groningen The Netherlands
| | - Gitte M. Knudsen
- Neurobiology Research Unit, Rigshospitalet and University of Copenhagen; Copenhagen Denmark
| | - Sietse F. de Boer
- Department of Behavioral Physiology; Center for Behavior and Neurosciences, University of Groningen; Groningen The Netherlands
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22
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de Medeiros Silva A, de Santana MAD, de Góis Morais PLA, de Sousa TB, Januário Engelberth RCG, de Souza Lucena EE, Campêlo CLDC, Sousa Cavalcante J, Cavalcante JC, de Oliveira Costa MSM, Nascimento ESD. Serotonergic fibers distribution in the midline and intralaminar thalamic nuclei in the rock cavy (Kerodon rupestris). Brain Res 2014; 1586:99-108. [DOI: 10.1016/j.brainres.2014.08.047] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Revised: 08/14/2014] [Accepted: 08/16/2014] [Indexed: 12/19/2022]
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Characterization of [11C]Cimbi-36 as an agonist PET radioligand for the 5-HT2A and 5-HT2C receptors in the nonhuman primate brain. Neuroimage 2014; 84:342-53. [DOI: 10.1016/j.neuroimage.2013.08.035] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 08/12/2013] [Accepted: 08/15/2013] [Indexed: 11/18/2022] Open
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Development of novel chiral capillary electrophoresis methods for the serotonin receptor (5-HT2A) antagonist MDL 100,907 (volinanserin) and for its key intermediate compound. J Pharm Biomed Anal 2013; 88:579-83. [PMID: 24216279 DOI: 10.1016/j.jpba.2013.10.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Revised: 10/01/2013] [Accepted: 10/06/2013] [Indexed: 11/21/2022]
Abstract
Enantioselective capillary electrophoretic methods were elaborated for the determination of the enantiomeric purity of (R)-MDL 100,907 and its preparatively resolved key intermediate compound during the synthesis route. The pKa values of the intermediate compound and the end product determined by CE were 10.5±0.1 and 9.0±0.1, respectively. The enantiopurity of the intermediate compound can be monitored in fully protonated state by applying 15mM sulfobutylether-β-cyclodextrin at pH 5 when the peak belonging to the impurity migrates before the main component. The fact that the consecutive steps of the synthesis do not affect the enantiomeric purity was verified by the other, newly developed CE method. The enantiomers of rac-MDL 100,907 were resolved by 15mM carboxymethyl-γ-cyclodextrin at pH 3. The applicability (selectivity, LOD, LOQ, repeatability, precision and accuracy) of the methods was studied as well.
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25
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Regulating Prefrontal Cortex Activation: An Emerging Role for the 5-HT2A Serotonin Receptor in the Modulation of Emotion-Based Actions? Mol Neurobiol 2013; 48:841-53. [DOI: 10.1007/s12035-013-8472-0] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Accepted: 05/06/2013] [Indexed: 10/26/2022]
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Celada P, Puig MV, Artigas F. Serotonin modulation of cortical neurons and networks. Front Integr Neurosci 2013; 7:25. [PMID: 23626526 PMCID: PMC3630391 DOI: 10.3389/fnint.2013.00025] [Citation(s) in RCA: 252] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Accepted: 04/01/2013] [Indexed: 01/20/2023] Open
Abstract
The serotonergic pathways originating in the dorsal and median raphe nuclei (DR and MnR, respectively) are critically involved in cortical function. Serotonin (5-HT), acting on postsynaptic and presynaptic receptors, is involved in cognition, mood, impulse control and motor functions by (1) modulating the activity of different neuronal types, and (2) varying the release of other neurotransmitters, such as glutamate, GABA, acetylcholine and dopamine. Also, 5-HT seems to play an important role in cortical development. Of all cortical regions, the frontal lobe is the area most enriched in serotonergic axons and 5-HT receptors. 5-HT and selective receptor agonists modulate the excitability of cortical neurons and their discharge rate through the activation of several receptor subtypes, of which the 5-HT1A, 5-HT1B, 5-HT2A, and 5-HT3 subtypes play a major role. Little is known, however, on the role of other excitatory receptors moderately expressed in cortical areas, such as 5-HT2C, 5-HT4, 5-HT6, and 5-HT7. In vitro and in vivo studies suggest that 5-HT1A and 5-HT2A receptors are key players and exert opposite effects on the activity of pyramidal neurons in the medial prefrontal cortex (mPFC). The activation of 5-HT1A receptors in mPFC hyperpolarizes pyramidal neurons whereas that of 5-HT2A receptors results in neuronal depolarization, reduction of the afterhyperpolarization and increase of excitatory postsynaptic currents (EPSCs) and of discharge rate. 5-HT can also stimulate excitatory (5-HT2A and 5-HT3) and inhibitory (5-HT1A) receptors in GABA interneurons to modulate synaptic GABA inputs onto pyramidal neurons. Likewise, the pharmacological manipulation of various 5-HT receptors alters oscillatory activity in PFC, suggesting that 5-HT is also involved in the control of cortical network activity. A better understanding of the actions of 5-HT in PFC may help to develop treatments for mood and cognitive disorders associated with an abnormal function of the frontal lobe.
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Affiliation(s)
- Pau Celada
- Department of Neurochemistry and Neuropharmacology, Institut d' Investigacions Biomèdiques de Barcelona (CSIC), IDIBAPS Barcelona, Spain ; Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM) Madrid, Spain
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27
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Talbot PS, Slifstein M, Hwang DR, Huang Y, Scher E, Abi-Dargham A, Laruelle M. Extended characterisation of the serotonin 2A (5-HT2A) receptor-selective PET radiotracer 11C-MDL100907 in humans: quantitative analysis, test-retest reproducibility, and vulnerability to endogenous 5-HT tone. Neuroimage 2011; 59:271-85. [PMID: 21782029 DOI: 10.1016/j.neuroimage.2011.07.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Revised: 06/29/2011] [Accepted: 07/01/2011] [Indexed: 11/17/2022] Open
Abstract
INTRODUCTION Scanning properties and analytic methodology of the 5-HT2A receptor-selective positron emission tomography (PET) tracer 11C-MDL100907 have been partially characterised in previous reports. We present an extended characterisation in healthy human subjects. METHODS 64 11C-MDL100907 PET scans with metabolite-corrected arterial input function were performed in 39 healthy adults (18-55 years). 12 subjects were scanned twice (duration 150 min) to provide data on plasma analysis, model order estimation, and stability and test-retest characteristics of outcome measures. All other scans were 90 min duration. 3 subjects completed scanning at baseline and following 5-HT2A receptor antagonist medication (risperidone or ciproheptadine) to provide definitive data on the suitability of the cerebellum as reference region. 10 subjects were scanned under reduced 5-HT and control conditions using rapid tryptophan depletion to investigate vulnerability to competition with endogenous 5-HT. 13 subjects were scanned as controls in clinical protocols. Pooled data were used to analyse the relationship between tracer injected mass and receptor occupancy, and age-related decline in 5-HT2A receptors. RESULTS Optimum analytic method was a 2-tissue compartment model with arterial input function. However, basis function implementation of SRTM may be suitable for measuring between-group differences non-invasively and warrants further investigation. Scan duration of 90 min achieved stable outcome measures in all cortical regions except orbitofrontal which required 120 min. Binding potential (BPP and BPND) test-retest variability was very good (7-11%) in neocortical regions other than orbitofrontal, and moderately good (14-20%) in orbitofrontal cortex and medial temporal lobe. Saturation occupancy of 5-HT2A receptors by risperidone validates the use of the cerebellum as a region devoid of specific binding for the purposes of PET. We advocate a mass limit of 4.6 μg to remain below 5% receptor occupancy. 11C-MDL100907 specific binding is not vulnerable to competition with endogenous 5-HT in humans. Paradoxical decreases in BPND were found in right prefrontal cortex following reduced 5-HT, possibly representing receptor internalisation. Mean age-related decline in brain 5-HT2A receptors was 14.0±5.0% per decade, and higher in prefrontal regions. CONCLUSIONS Our data confirm and extend support for 11C-MDL100907 as a PET tracer with very favourable properties for quantifying 5-HT2A receptors in the human brain.
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Affiliation(s)
- Peter S Talbot
- Department of Psychiatry, Columbia University College of Physicians and Surgeons and the New York State Psychiatric Institute, New York, NY 10032, USA.
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Paterson LM, Kornum BR, Nutt DJ, Pike VW, Knudsen GM. 5-HT radioligands for human brain imaging with PET and SPECT. Med Res Rev 2011; 33:54-111. [PMID: 21674551 DOI: 10.1002/med.20245] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The serotonergic system plays a key modulatory role in the brain and is the target for many drug treatments for brain disorders either through reuptake blockade or via interactions at the 14 subtypes of 5-HT receptors. This review provides the history and current status of radioligands used for positron emission tomography (PET) and single photon emission computerized tomography (SPECT) imaging of human brain serotonin (5-HT) receptors, the 5-HT transporter (SERT), and 5-HT synthesis rate. Currently available radioligands for in vivo brain imaging of the 5-HT system in humans include antagonists for the 5-HT(1A), 5-HT(1B), 5-HT(2A), and 5-HT(4) receptors, and for SERT. Here we describe the evolution of these radioligands, along with the attempts made to develop radioligands for additional serotonergic targets. We describe the properties needed for a radioligand to become successful and the main caveats. The success of a PET or SPECT radioligand can ultimately be assessed by its frequency of use, its utility in humans, and the number of research sites using it relative to its invention date, and so these aspects are also covered. In conclusion, the development of PET and SPECT radioligands to image serotonergic targets is of high interest, and successful evaluation in humans is leading to invaluable insight into normal and abnormal brain function, emphasizing the need for continued development of both SPECT and PET radioligands for human brain imaging.
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Affiliation(s)
- Louise M Paterson
- Neuropsychopharmacology Unit, Division of Experimental Medicine, Imperial College London, Burlington Danes Building, Du Cane Road, London, United Kingdom
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29
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Dougherty JP, Aloyo VJ. Pharmacological and behavioral characterization of the 5-HT2A receptor in C57BL/6N mice. Psychopharmacology (Berl) 2011; 215:581-93. [PMID: 21340474 DOI: 10.1007/s00213-011-2207-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2010] [Accepted: 01/27/2011] [Indexed: 11/30/2022]
Abstract
RATIONALE The serotonin (5-HT) 2A receptor is implicated in numerous psychiatric disorders, making it an important, clinically relevant target. Despite the availability of transgenic mouse lines, the native mouse 5-HT(2A) receptor is not well-characterized. OBJECTIVES The goals of the current study were to determine 5-HT(2A) and 5-HT(2C) receptor densities in mouse cortex, establish a pharmacological profile of the mouse 5-HT(2A) receptor, and determine the effects of chronic drug treatment on 5-HT(2A) receptor density and 5-HT(2A) receptor-mediated behavior. METHODS Receptor densities were determined in cortex and frontal cortex via saturation binding assays using [(3)H]ketanserin or [(3)H]mesulergine. A pharmacological profile was established by displacing [(3)H]ketanserin binding with several ligands. Chronic treatment with 5-HT(2A/2C) receptor agonist, 2,5-dimethoxy-4-iodoamphetamine (DOI), 5-HT(2A) receptor antagonist, MDL 11939, or vehicle was followed by 5-HT(2A) receptor density determination. Head twitch responses (HTRs) were counted on select days. RESULTS Mice had high 5-HT(2A), but low 5-HT(2C) receptor densities. Ligand binding affinities for mouse 5-HT(2A) receptors correlated with rat, but not rabbit or human, affinities. Chronically DOI-treated mice displayed reduced HTRs and 5-HT(2A) receptor density compared to saline-treated mice. Receptor density was unchanged following chronic treatment with MDL 11939. CONCLUSIONS The current study provides some basic information about mouse 5-HT(2A) and 5-HT(2C) receptors and provides comparisons to rats, rabbits, and humans. The current chronic agonist treatment study demonstrated an important similarity between the 5-HT(2A) receptor in mice, rats, and rabbits, while antagonist treatment revealed an interesting difference from previous studies in rabbits.
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Affiliation(s)
- John P Dougherty
- Drexel University College of Medicine, Philadelphia, PA 19102, USA.
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Navailles S, De Deurwaerdère P. Presynaptic control of serotonin on striatal dopamine function. Psychopharmacology (Berl) 2011; 213:213-42. [PMID: 20953589 DOI: 10.1007/s00213-010-2029-y] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2010] [Accepted: 09/14/2010] [Indexed: 11/27/2022]
Abstract
RATIONALE The influences of the serotonergic system on dopamine (DA) neuron activity have received considerable attention during the last three decades due to the real opportunity to improve disorders related to central DA neuron dysfunctions such as Parkinson's disease, schizophrenia, or drug abuse with serotonergic drugs. Numerous biochemical and behavioral data indicate that serotonin (5-HT) affects dopaminergic terminal function in the striatum. OBJECTIVE The authors propose a thorough examination of data showing controversial effects induced by striatal 5-HT on dopaminergic activity. RESULTS Inhibitory and excitatory effects of exogenous 5-HT have been reported on DA release and synthesis, involving various striatal 5-HT receptors. 5-HT also promotes an efflux of DA through reversal of the direction of DA transport. By analogy with the mechanism of action described for amphetamine, the consequences of 5-HT entering DA terminals might explain both the excitatory and inhibitory effects of 5-HT on presynaptic DA terminal activity, but the physiological relevance of this mechanism is far from clear. The recent data suggest that the endogenous 5-HT system affects striatal DA release in a state-dependent manner associated with the conditional involvement of various 5-HT receptors such as 5-HT(2A), 5-HT(2C), 5-HT(3), and 5-HT(4) receptors. CONCLUSION Methodological and pharmacological issues have prevented a comprehensive overview of the influence of 5-HT on striatal DA activity. The distribution of striatal 5-HT receptors and their restricted influence on DA neuron activity suggest that the endogenous 5-HT system exerts multiple and subtle influences on DA-mediated behaviors.
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Affiliation(s)
- Sylvia Navailles
- Unité Mixte de Recherche Centre National de la Recherche Scientifique 5227, Université Victor Segalen Bordeaux 2, Bordeaux, France
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Ettrup A, Kornum BR, Weikop P, Knudsen GM. An approach for serotonin depletion in pigs: Effects on serotonin receptor binding. Synapse 2010; 65:136-45. [DOI: 10.1002/syn.20827] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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Electrophysiology of Serotonin Receptors. ACTA ACUST UNITED AC 2010. [DOI: 10.1016/s1569-7339(10)70077-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Mengod G, Cortés R, Vilaró MT, Hoyer D. Distribution of 5-HT Receptors in the Central Nervous System. HANDBOOK OF BEHAVIORAL NEUROSCIENCE 2010. [DOI: 10.1016/s1569-7339(10)70074-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Abstract
The recent increase in radioligands available for neuroimaging major depressive disorder has led to advancements in our understanding of the pathophysiology of this illness and improved antidepressant development. Major depressive disorder can be defined as an illness of recurrent major depressive episodes of persistently low mood, dysregulated sleep, appetite and weight, anhedonia, cognitive impairment, and suicidality. The main target sites investigated with radioligand neuroimaging include receptor sites that regulate in response to lowered monoamine levels, targets related to removal of monoamines, uptake of ligands related to regional brain function, and target sites of antidepressants.
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Affiliation(s)
- Jeffrey H Meyer
- Department of Psychiatry, University of Toronto, Toronto, Canada.
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de Almeida J, Mengod G. Quantitative analysis of glutamatergic and GABAergic neurons expressing 5-HT(2A) receptors in human and monkey prefrontal cortex. J Neurochem 2007; 103:475-86. [PMID: 17635672 DOI: 10.1111/j.1471-4159.2007.04768.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
5-hydroxytryptamine (5-HT) or serotonin 2A receptors play an important role in modulation of prefrontal cortex (PFC) activity and have been implicated in the physiopathology of psychiatric disorders. There is no quantitative information on the percentage of glutamatergic and GABAergic cells that express 5-HT(2A) receptors in human and monkey PFC. We have used double in situ hybridization to quantify the mRNA co-localization of 5-HT(2A) receptor with the glutamatergic transporter vesicular glutamate transporter 1, and with the GABAergic marker glutamic acid decarboxylase 65/67 and in parvalbumin and calbindin GABAergic cell populations. Our results show that nearly every glutamatergic cell (86-100%) in layers II-V expressed 5-HT(2A) receptor mRNA in both species. This percentage was lower in layer VI (13-31%). In contrast, not all the GABAergic interneurons (13-46%) expressed 5-HT(2A) receptor mRNA. This receptor was expressed in 45-69% of parvalbumin and in 61-87% of calbindin positive cells. These results indicate that, while the majority of glutamatergic neurons can be sensitive to 5-HT action via 5-HT(2A) receptors, this modulation occurs only in a limited population of GABAergic interneurons and provides new neuroanatomical information about the role played by serotonin through 5-HT(2A) receptors in the PFC and on the sites of action for drugs such as antipsychotics and antidepressants used in treatment of psychiatric disorders.
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Affiliation(s)
- J de Almeida
- Department of Neuropharmacology, Institut d'Investigacions Biomèdiques de Barcelona (CSIC), IDIBAPS, Barcelona, Spain
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Marek GJ. A Novel Approach to the Identification of Psychiatric Drugs: Serotonin-Glutamate Interactions in the Prefrontal Cortex. CNS DRUG REVIEWS 2006. [DOI: 10.1111/j.1527-3458.2000.tb00148.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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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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Mengod G, Vilaró MT, Cortés R, López-Giménez JF, Raurich A, Palacios JM. Chemical Neuroanatomy of 5-HT Receptor Subtypes in the Mammalian Brain. THE SEROTONIN RECEPTORS 2006. [DOI: 10.1007/978-1-59745-080-5_10] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Bortolozzi A, Díaz-Mataix L, Scorza MC, Celada P, Artigas F. The activation of 5-HT2A receptors in prefrontal cortex enhances dopaminergic activity. J Neurochem 2005; 95:1597-607. [PMID: 16277612 DOI: 10.1111/j.1471-4159.2005.03485.x] [Citation(s) in RCA: 146] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Atypical antipsychotics show preferential 5-HT 2A versus dopamine (DA) D2 receptor affinity. At clinical doses, they fully occupy cortical 5-HT2 receptors, which suggests a strong relationship with their therapeutic action. Half of the pyramidal neurones in the medial prefrontal cortex (mPFC) express 5-HT 2A receptors. Also, neurones excited through 5-HT 2A receptors project to the ventral tegmental area (VTA). We therefore hypothesized that prefrontal 5-HT 2A receptors can modulate DA transmission through excitatory mPFC-VTA inputs. In this study we used single unit recordings to examine the responses of DA neurones to local (in the mPFC) and systemic administration of the 5-HT 2A/2C agonist 1-[2,5-dimethoxy-4-iodophenyl-2-aminopropane] (DOI). Likewise, using microdialysis, we examined DA release in the mPFC and VTA (single/dual probe) in response to prefrontal and systemic drug administration. The local (in the mPFC) and systemic administration of DOI increased the firing rate and burst firing of DA neurones and DA release in the VTA and mPFC. The increase in VTA DA release was mimicked by the electrical stimulation of the mPFC. The effects of DOI were reversed by M100907 and ritanserin. These results indicate that the activity of VTA DA neurones is under the excitatory control of 5-HT 2A receptors in the mPFC. These observations may help in the understanding of the therapeutic action of atypical antipsychotics.
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Affiliation(s)
- Analía Bortolozzi
- Department of Neurochemistry, Institut d'Investigacions Biomèdiques de Barcelona (CSIC), IDIBAPS, Barcelona, Spain
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Wolf WA, Bieganski GJ, Guillen V, Mignon L. Enhanced 5-HT2C receptor signaling is associated with haloperidol-induced "early onset" vacuous chewing in rats: implications for antipsychotic drug therapy. Psychopharmacology (Berl) 2005; 182:84-94. [PMID: 15986194 DOI: 10.1007/s00213-005-0033-4] [Citation(s) in RCA: 18] [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: 01/06/2005] [Accepted: 04/01/2005] [Indexed: 10/25/2022]
Abstract
RATIONALE Haloperidol is a representative of typical antipsychotics that are still in clinical use and which can lead to abnormal motor activity following repeated administration. The mechanisms underlying antipsychotic-induced dyskinesias are not well understood but are widely held to be related to excessive loss of dopamine function. In several models of dopamine hypofunction, serotonin 5-HT2C receptors have been shown to mediate vacuous chewing movements (VCM), a form of abnormal motor activity. It is well established that repeated haloperidol administration also elicits VCM, but there is no information on how repeated haloperidol administration affects 5-HT2C receptor signaling. OBJECTIVES In the present study, we tested the hypothesis that repeated daily administration of haloperidol leads to enhanced serotonin 5-HT2C receptor signaling that is associated with increased 5-HT2C-mediated VCM. METHODS Rats were treated by subcutaneous injection once daily for 21 days with either vehicle, a low dose of haloperidol (0.1 mg kg(-1) day(-1)), or a high dose of haloperidol (1.0 mg kg(-1) day(-1)). Following 1-day withdrawal, rats were either used for behavioral scoring of VCM or sacrificed for biochemical assessment of 5-HT2 receptor-mediated phospholipase C activity and radioligand binding. VCM were scored following two successive "drug" challenges. The first challenge was an injection of vehicle (0.9% saline), and the second challenge was an injection of the 5-HT2C agonist meta-chlorophenylpiperazine (1.0 mg/kg). In this manner, a measure of "spontaneous" and "5-HT2C-elicited" orofacial activity could be made while minimizing animal use. RESULTS Following 21-day haloperidol treatment at either dose, there was an increase in expression of meta-chlorophenylpiperazine-induced VCM. In a separate experiment, meta-chlorophenylpiperazine-induced VCM were shown to be mediated through 5-HT2C receptors. Striatal 5-HT2C receptor-mediated phospholipase C (PLC) activity and high-affinity agonist-labeled 5-HT2C receptors were also increased following either dose of haloperidol as compared to vehicle treatment. GTP-stimulated PLC activity and striatal Gq proteins were unchanged by haloperidol suggesting that enhanced signaling could be accounted for by alterations at the level of the receptor and not at downstream mechanisms. CONCLUSIONS Repeated daily administration of haloperidol leads to an adaptive increase in 5-HT2C signaling which may contribute to abnormal motor function associated with antipsychotic use.
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Affiliation(s)
- William A Wolf
- Research Service-151, Edward Hines Jr. VA Hospital, Hines, IL 60141, USA.
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Kristiansen H, Elfving B, Plenge P, Pinborg LH, Gillings N, Knudsen GM. Binding characteristics of the 5-HT2A receptor antagonists altanserin and MDL 100907. Synapse 2005; 58:249-57. [PMID: 16206185 DOI: 10.1002/syn.20205] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
To study the 5-HT(2A) receptors in the living human brain, using positron emission tomography (PET), two selective radiotracers are currently in use: [(18)F]altanserin and [(11)C]MDL 100907. It is, however, currently unknown to what extent data obtained with either tracer are directly comparable. The aim of this study was to compare binding characteristics of these two radiotracers in rat brain with respect to affinity (K(d)), receptor binding density (B(max)), binding potential (BP), and nonspecific binding. Further, binding kinetics, sensitivity towards competition with the endogenous transmitter serotonin, and the competitive/noncompetitive interaction between the two radioligands were evaluated. In addition, the selectivity of [(18)F]altanserin for the 5-HT(2A) receptor was assessed. The K(d) value of [(18)F]altanserin and [(3)H]MDL 100907 was in the order of 0.3 nM. B(max) in frontal cortex was 523 and 527 fmol/mg protein, respectively. The binding of [(18)F]altanserin was not influenced by blocking either the 5-HT(2B/2C) or the alpha(1)-adrenergic receptors. At 37 degrees C the association t(1/2) was 2.8 and 2.7 min and the dissociation t(1/2) was 11 and 13.5 min for [(18)F]altanserin and [(3)H]MDL 100907, respectively. Both radioligands were displaced by 5-HT, only at high concentrations; the K(i) value of 5-HT ranging between 650 and 3,300 nM. This indicates that binding of both radioligands in PET studies is not directly influenced by changes in endogenous 5-HT.Overall, the binding of [(18)F]altanserin and [(3)H]MDL 100907 to the 5-HT(2A) receptor was very comparable, showing selective high affinity binding in the subnanomolar range.
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Affiliation(s)
- Heidi Kristiansen
- Neurobiology Research Unit, University Hospital Rigshospitalet, Copenhagen, Denmark
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Hirani E, Sharp T, Sprakes M, Grasby P, Hume S. Fenfluramine evokes 5-HT2A receptor-mediated responses but does not displace [11C]MDL 100907: small animal PET and gene expression studies. Synapse 2004; 50:251-60. [PMID: 14515343 DOI: 10.1002/syn.10268] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The in vivo binding of the 5-HT(2A) receptor-selective positron emission tomography (PET) ligand [(11)C]MDL 100907 and its sensitivity to endogenous 5-HT were quantified in rat brain using quad-HIDAC, a novel high-resolution PET camera for small animals. Specific binding of [(11)C]MDL 100907, estimated using volume of interest (VOI) to cerebellum ratios, corresponded well with both the known distribution of 5-HT(2A) receptors and tissue:cerebellum ratios obtained using ex vivo dissection. Specific binding was blocked by predosing with either nonradioactive MDL 100907 (0.2 or 0.4 mg/kg i.v.) or the 5-HT(2A/2C) receptor antagonist ketanserin (2 mg/kg i.v.), but was unaffected in rats pretreated with the 5-HT releasing agent, fenfluramine (10 mg/kg i.p.). In parallel studies, the same dose of fenfluramine was shown to be sufficient to cause an increase in the expression of the immediate early genes (IEG) c-fos and Arc mRNA in cortical regions with high 5-HT(2A) receptor density. This increase was blocked by MDL 100907 (0.2 mg/kg i.v.), confirming a 5-HT(2A) receptor-mediated effect. The results demonstrate that PET with [(11)C]MDL 100907 is insensitive to an increased concentration of synaptic 5-HT, implying that the ligand can be used clinically to monitor 5-HT(2A) receptor function or dysfunction in disease or during therapy, without the need to consider concomitant changes in neurotransmitter concentration.
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Affiliation(s)
- Ella Hirani
- Imaging Research Solutions Ltd., Cyclotron Building, London W12 0NN, UK.
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Abstract
This study reviews the role of the serotonin 5-HT2A receptor in learning as measured by the acquisition of the rabbit's classically conditioning nictitating membrane response, a component of the eyeblink response. Agonists at the 5-HT2A receptor including LSD (d-lysergic acid diethylamide) enhanced associative learning at doses that produce cognitive effects in humans. Some antagonists such as BOL (d-bromolysergic acid diethylamide), LY53,857, and ketanserin acted as neutral antagonists in that they had no effect on learning, whereas others (MDL11,939, ritanserin, and mianserin) acted as inverse agonists in that they retarded learning through an action at the 5-HT2A receptor. These results were placed in the context of what is known concerning the anatomical distribution and electrophysiological effects of 5-HT2A receptor activation in frontal cortex and hippocampus, as well as the role of cortical 5-HT2A receptors in schizophrenia. It was concluded that the 5-HT2A receptor demonstrates constitutive activity, and that variations in this activity can produce profound alterations in cognitive states.
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Affiliation(s)
- John A Harvey
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19118, USA.
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Abstract
Fear is an adaptive component of the acute "stress" response to potentially-dangerous (external and internal) stimuli which threaten to perturb homeostasis. However, when disproportional in intensity, chronic and/or irreversible, or not associated with any genuine risk, it may be symptomatic of a debilitating anxious state: for example, social phobia, panic attacks or generalized anxiety disorder. In view of the importance of guaranteeing an appropriate emotional response to aversive events, it is not surprising that a diversity of mechanisms are involved in the induction and inhibition of anxious states. Apart from conventional neurotransmitters, such as monoamines, gamma-amino-butyric acid (GABA) and glutamate, many other modulators have been implicated, including: adenosine, cannabinoids, numerous neuropeptides, hormones, neurotrophins, cytokines and several cellular mediators. Accordingly, though benzodiazepines (which reinforce transmission at GABA(A) receptors), serotonin (5-HT)(1A) receptor agonists and 5-HT reuptake inhibitors are currently the principle drugs employed in the management of anxiety disorders, there is considerable scope for the development of alternative therapies. In addition to cellular, anatomical and neurochemical strategies, behavioral models are indispensable for the characterization of anxious states and their modulation. Amongst diverse paradigms, conflict procedures--in which subjects experience opposing impulses of desire and fear--are of especial conceptual and therapeutic pertinence. For example, in the Vogel Conflict Test (VCT), the ability of drugs to release punishment-suppressed drinking behavior is evaluated. In reviewing the neurobiology of anxious states, the present article focuses in particular upon: the multifarious and complex roles of individual modulators, often as a function of the specific receptor type and neuronal substrate involved in their actions; novel targets for the management of anxiety disorders; the influence of neurotransmitters and other agents upon performance in the VCT; data acquired from complementary pharmacological and genetic strategies and, finally, several open questions likely to orientate future experimental- and clinical-research. In view of the recent proliferation of mechanisms implicated in the pathogenesis, modulation and, potentially, treatment of anxiety disorders, this is an opportune moment to survey their functional and pathophysiological significance, and to assess their influence upon performance in the VCT and other models of potential anxiolytic properties.
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Affiliation(s)
- Mark J Millan
- Psychopharmacology Department, Centre de Rescherches de Croissy, Institut de Recherches (IDR) Servier, 125 Chemin de Ronde, 78290 Croissy-sur-Seine, Paris, France.
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Abstract
Serotonergic fibers broadly innervate the thalamus and may influence the sleep wake cycle, attention, and other processes through modulation of neurons in this structure. However, the actions of serotonin in the dorsal thalamus have been investigated in detail only in the dorsal lateral geniculate nucleus. In the present study, we examined the action of serotonin in several different regions of the ferret dorsal thalamus, including the associative nuclei, using the in vitro slice preparation and intracellular recording techniques. In nearly all nuclei examined, the predominant action of serotonin was one of hyperpolarization and inhibition of the tonic firing mode. The magnitude of the hyperpolarizing response decreased with age and varied greatly across and somewhat within nuclei maintaining the following relationship (in descending order of magnitude): lateral posterior, lateral dorsal, pulvinar, mediodorsal, center median, anteroventral, central lateral, ventral basal, and medial geniculate. This hyperpolarization is elicited through two mechanisms: one direct and the other via local interneurons. The direct action occurs through an increase in potassium conductance mediated through the 5-HT(1A) receptor. This conclusion is supported by the findings that it persists in the presence of tetrodotoxin and block of GABAergic synaptic transmission, the reversal potential shifts in a Nernstian fashion with changes in extracellular potassium concentration, and the response is antagonized by the 5-HT(1A) antagonist WAY100635 and mimicked by the application of the 5-HT(1A)-selective agonist 8-OH DPAT. The second mechanism by which 5-HT evoked a hyperpolarization was through the activation of local interneurons. In slices in which GABA receptors were not blocked, 5-HT application increased the frequency and amplitude of spontaneous inhibitory postsynaptic potentials (IPSPs) occurring in thalamocortical neurons. Application of 5-HT to physiologically or morphologically identified interneurons evoked a prolonged suprathreshold depolarization. Our results suggest that serotonergic inputs act differentially across the thalamus in a complex manner involving direct and indirect mechanisms. It appears that 5-HT has a greater direct postsynaptic inhibitory influence in the posterior, medial, and intralaminar nuclei than in the primary sensory nuclei.
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Affiliation(s)
- James E Monckton
- Section of Neurobiology, Yale University School of Medicine, New Haven, Connecticut 06510, USA
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Szabo ST, Blier P. Functional and pharmacological characterization of the modulatory role of serotonin on the firing activity of locus coeruleus norepinephrine neurons. Brain Res 2001; 922:9-20. [PMID: 11730697 DOI: 10.1016/s0006-8993(01)03121-3] [Citation(s) in RCA: 109] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Previous studies, using in vivo extracellular unitary recordings in anaesthetized rats, have shown that the selective 5-HT(1A) receptor antagonist WAY 100,635 suppressed the firing rate of locus coeruleus (LC) norepinephrine (NE) neurons and that this effect was abolished by lesioning 5-HT neurons. In the present experiments, the selective 5-HT(2A) receptor antagonist MDL 100,907, while having no effect on the spontaneous firing activity of LC neurons in controls, was able to restore NE neuronal discharges following the injection of WAY 100,635. The 5-HT(1A) receptor agonist 8-OH-DPAT enhanced the firing activity of NE neurons and this action was entirely dependent on intact 5-HT neurons, unlike the inhibitory effect of the 5-HT(2) receptor agonist DOI. Taken together, these data indicate that 5-HT(2A) but not 5-HT(1A) receptors controlling LC firing activity are postsynaptic to 5-HT neurons. Prolonged, but not subacute, administration of selective 5-HT reuptake inhibitors (SSRIs) produces a decrease in the spontaneous firing activity of LC NE neurons. MDL 100,907 partially reversed this suppressed firing activity of LC neurons in paroxetine-treated rats. Although the alpha(2)-adrenoceptor antagonist idazoxan also enhanced the firing activity of NE neurons in paroxetine-treated rats, this increase was similar to that obtained in controls. In conclusion, prolonged SSRI treatment enhances a tonic inhibitory influence by 5-HT on LC neurons through postsynaptic 5-HT(2A) receptors that are not located on NE neurons. A speculative neuronal circuitry accounting for these phenomena on LC NE activity is proposed.
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Affiliation(s)
- S T Szabo
- Neurobiological Psychiatry Unit, McGill University, Montréal, Quebec, Canada H3A 1A1
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López-Giménez JF, Mengod G, Palacios JM, Vilaró MT. Regional distribution and cellular localization of 5-HT2C receptor mRNA in monkey brain: comparison with [3H]mesulergine binding sites and choline acetyltransferase mRNA. Synapse 2001; 42:12-26. [PMID: 11668587 DOI: 10.1002/syn.1095] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The distribution of serotonin 5-HT(2C) receptor mRNA in monkey brain was studied by in situ hybridization and compared with the distribution of [3H]mesulergine binding sites as visualized by receptor autoradiography. 5-HT(2C) receptor transcripts showed a widespread and heterogeneous distribution. The strongest hybridization signal was detected in choroid plexus. In neocortex, 5-HT(2C) mRNA was detected in layer V of all cortical regions examined except in the calcarine sulcus, which was devoid of signal. Several structures within the striatum and basal forebrain were strongly labeled: nucleus accumbens, ventral aspects of anterior caudate and putamen, septal nuclei, diagonal band, ventral striatum, and extended amygdala. Several thalamic, midbrain, and brainstem nuclei also contained 5-HT(2C) mRNA. Comparison of the distributions of 5-HT(2C) mRNA and specific [3H]mesulergine binding sites showed a good agreement in the majority of brain regions, suggesting a predominant somatodendritic localization of 5-HT(2C) receptors. A possible localization to axon terminals of 5-HT(2C) receptors is suggested by the disagreement observed in some regions such as septal nuclei and horizontal limb of the diagonal band (presence of mRNA with apparent absence of binding sites) and interpeduncular nucleus (presence of binding sites with apparent absence of mRNA). Comparison of 5-HT(2C) receptor and choline acetyltransferase mRNA distributions indicate that some regions where cholinergic cells are located are also enriched in cells containing 5-HT(2C) mRNA. Although the present methodology does not allow strict colocalization of both mRNA species to the same cells, the codistribution observed in several regions provides a possible anatomical substrate for the described modulation of acetylcholine release by 5-HT(2C) receptors.
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Affiliation(s)
- J F López-Giménez
- Department of Neurochemistry, Instituto de Investigaciones Biomédicas de Barcelona, Consejo Superior de Investigaciones Científicas (IIBB-CSIC, IDIBAPS), E-08036 Barcelona, Spain
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48
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Zhang YQ, Gao X, Ji GC, Wu GC. Expression of 5-HT2A receptor mRNA in rat spinal dorsal horn and some nuclei of brainstem after peripheral inflammation. Brain Res 2001; 900:146-51. [PMID: 11325358 DOI: 10.1016/s0006-8993(01)02283-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The expression of 5-hydroxytryptamine 5-HT2A receptor mRNA was studied in the lumbar spinal dorsal horn, nucleus of raphe magnus (NRM), ventrolateral periaqueductal gray (vlPAG) and dorsal raphe nucleus (DRN) following carrageenan inflammation using in situ hybridization technique. The findings of this study demonstrated that 5-HT2A receptor mRNA was expressed with low to moderate levels in lumbar spinal dorsal horn, NRM, vlPAG and DRN. Following carrageenan inflammation, the expression of 5-HT2A receptor mRNA in ipsilateral dorsal horn, bilateral NRM, vlPAG and DRN was significantly increased. The peak occurred at 3 h and then there was a clear decrease but still a substantial number of labeled cells at 24 h after injection of carrageenan. This result suggested that the synthesis of 5-HT2A receptor is enhanced in spinal dorsal horn, NRM, vlPAG and DRN during inflammatory pain.
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Affiliation(s)
- Y Q Zhang
- State Key Laboratory of Medical Neurobiology, Department of Neurobiology, Medical Center of Fudan University, 138 Yi Xue Yuan Road, 200032, Shanghai, People's Republic of China
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49
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Wadenberg MG, Browning JL, Young KA, Hicks PB. Antagonism at 5-HT(2A) receptors potentiates the effect of haloperidol in a conditioned avoidance response task in rats. Pharmacol Biochem Behav 2001; 68:363-70. [PMID: 11325387 DOI: 10.1016/s0091-3057(00)00483-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
High affinity for serotonin-2A (5-HT(2A)) over dopamine (DA) D(2) receptors is a leading hypothesis for clozapine's favorable therapeutic profile. Recent preclinical studies also indicate that a sufficient antipsychotic effect might be obtained by a combined high 5-HT(2A)/low D(2) receptor blockade. Thus, addition of a 5-HT(2A) receptor antagonist to an ineffective dose of a D(2) receptor antagonist produces a robust antipsychotic-like effect in the conditioned avoidance response (CAR) test. Electrophysiological and biochemical studies also show that 5-HT(2A) receptor antagonists can confer an atypical (clozapine-like) profile on a D(2) receptor antagonist. Improved therapeutic efficacy by adjunctive 5-HT(2A) receptor antagonist treatment to a traditional D(2) receptor blocking regimen has been suggested. However, the ability of 5-HT(2A) receptor blockade to protect against, or ameliorate, parkinsonian symptoms still remains unclear. Using the CAR and the catalepsy (CAT) tests as indices for antipsychotic activity and extrapyramidal side effect (EPS) liability, respectively, the effects of the selective 5-HT(2A) receptor antagonist MDL 100,907 in combination with the DA D(2) receptor antagonists haloperidol or raclopride were studied in rats. Haloperidol (0.025 or 0.1 mg/kg sc, -30 min) produced a dose-dependent suppression of CAR. Pretreatment with MDL 100,907 (0.5, 1.0, or 1.5 mg/kg sc; -60 min) enhanced and prolonged the haloperidol-induced suppression of CAR without escape failures. MDL 100,907 (1 mg/kg sc, -60 min) had no effect on CAT when coadministered with ineffective doses of raclopride. Raclopride (1 mg/kg sc, -30 min) alone produced a submaximal cataleptic response that was significantly enhanced by pretreatment with MDL 100,907. The present results confirm and extend previous results by showing that 5-HT(2A) receptor blockade can enhance the antipsychotic-like effects of a very low dose of a commonly used traditional antipsychotic. 5-HT(2A) receptor blockade does not, however, prevent EPS (CAT). The therapeutic advantage of this combination might, therefore, operate within a fairly narrow window.
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Affiliation(s)
- M G Wadenberg
- Department of Psychiatry, Scott & White Clinic and Scott & White Memorial Hospital, Temple, TX 76508, USA.
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50
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López-Giménez JF, Vilaró MT, Palacios JM, Mengod G. Mapping of 5-HT2A receptors and their mRNA in monkey brain: [3H]MDL100,907 autoradiography and in situ hybridization studies. J Comp Neurol 2001; 429:571-89. [PMID: 11135236 DOI: 10.1002/1096-9861(20010122)429:4<571::aid-cne5>3.0.co;2-x] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The anatomic distribution of serotonin 5-HT2A receptors visualized with [3H]MDL100,907 and of their mRNA detected by in situ hybridization were studied in monkey brain. Both autoradiographic patterns of signal showed heterogeneous distributions and were in general in good agreement in the majority of brain regions. In most neocortical areas, [3H]MDL100,907 presented a four-banded pattern with layers I and III-IV more intensely labeled and layers II and V-VI showing weaker labeling. 5-HT2A receptor mRNA was detected in layers III and IV, and in some cases also in layers II and V. In intra- and extra-calcarine areas of striate cortex a five-banded pattern was distinguished, with layers III and IVc-V showing the highest densities of [3H]MDL100,907 labeling. These two areas showed the highest neocortical hybridization signal. An unexpected finding was the presence of low densities of [3H]MDL100,907 labeling and 5-HT2A receptor mRNA in choroid plexus. Comparison of the distribution of [3H]MDL100,907 and [3H]ketanserin binding sites in monkey brain regions with high nonspecific [3H]ketanserin binding (caudate, putamen, substantia nigra, inferior olive) revealed specific binding of [3H]MDL100,907 with very low nonspecific binding. Some differences were noted between the distribution of [3H]MDL100,907-labeled 5-HT2A receptors in monkey brain and the previously reported distribution of these receptors in human brain: absence of striosome labeling in monkey striatum and different patterns of neocortical labeling. The present results provide the first detailed comparison of 5-HT2A receptor and mRNA distribution in primate brain. The observed species differences in 5-HT2A receptor distribution should be considered when extrapolating results among different species.
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Affiliation(s)
- J F López-Giménez
- Department of Neurochemistry, Instituto de Investigaciones Biomédicas de Barcelona, Consejo Superior de Investigaciones Científícas (CSIC), IDIBAPS, E-08036 Barcelona, Spain
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