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Fernandes HDB, Oliveira BDS, Machado CA, Carvalho BC, de Brito Toscano EC, da Silva MCM, Vieira ÉLM, de Oliveira ACP, Teixeira AL, de Miranda AS, da Silva AM. Behavioral, neurochemical and neuroimmune features of RasGEF1b deficient mice. Prog Neuropsychopharmacol Biol Psychiatry 2024; 129:110908. [PMID: 38048936 DOI: 10.1016/j.pnpbp.2023.110908] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 11/02/2023] [Accepted: 11/28/2023] [Indexed: 12/06/2023]
Abstract
The factor RasGEF1b is a Ras guanine exchange factor involved in immune responses. Studies have also implicated RasGEF1b in the CNS development. It is still limited the understanding of the role of RasGEF1b in CNS functioning. Using RasGEF1b deficient mice (RasGEF1b-cKO), we investigated the impact of this gene deletion in behavior, cognition, brain neurochemistry and microglia morphology. We showed that RasGEF1b-cKO mice display spontaneous hyperlocomotion and anhedonia. RasGEF1b-cKO mice also exhibited compulsive-like behavior that was restored after acute treatment with the selective serotonin reuptake inhibitor (SSRI) fluoxetine (5 mg/kg). A down-regulation of mRNA of dopamine receptor (Drd1, Drd2, Drd4 and Drd5) and serotonin receptor genes (5Htr1a, 5Htr1b and 5Htr1d) was observed in hippocampus of RasGEF1b-cKO mice. These mice also had reduction of Drd1 and Drd2 in prefrontal cortex and 5Htr1d in striatum. In addition, morphological alterations were observed in RasGEF1b deficient microglia along with decreased levels of hippocampal BDNF. We provided original evidence that the deletion of RasGEF1b leads to unique behavioral features, implicating this factor in CNS functioning.
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Affiliation(s)
- Heliana de Barros Fernandes
- Laboratório de Genes Inflamatórios, Departamento de Morfologia, Universidade Federal de Minas Gerais, Av. Presidente Antônio Carlos, 6627, Pampulha, CEP: 31270-901, Belo Horizonte, MG, Brazil; Laboratório de Neurobiologia, Departamento de Morfologia, Universidade Federal de Minas Gerais, Av. Presidente Antônio Carlos, 6627, Pampulha, CEP: 31270-901, Belo Horizonte, MG, Brazil.
| | - Bruna da Silva Oliveira
- Laboratório de Neurobiologia, Departamento de Morfologia, Universidade Federal de Minas Gerais, Av. Presidente Antônio Carlos, 6627, Pampulha, CEP: 31270-901, Belo Horizonte, MG, Brazil
| | - Caroline Amaral Machado
- Laboratório de Neurobiologia, Departamento de Morfologia, Universidade Federal de Minas Gerais, Av. Presidente Antônio Carlos, 6627, Pampulha, CEP: 31270-901, Belo Horizonte, MG, Brazil
| | - Brener Cunha Carvalho
- Laboratório de Genes Inflamatórios, Departamento de Morfologia, Universidade Federal de Minas Gerais, Av. Presidente Antônio Carlos, 6627, Pampulha, CEP: 31270-901, Belo Horizonte, MG, Brazil
| | - Eliana Cristina de Brito Toscano
- Laboratório Integrado de Pesquisas em Patologia, Departamento de Patologia, Faculdade de Medicina, Universidade Federal de Juiz de Fora, Av. Eugênio do Nascimento, s/n°, Dom Bosco, CEP: 36038-330, Juiz de Fora, MG, Brazil
| | - Maria Carolina M da Silva
- Laboratório de Neurofarmacologia, Departamento de Fisiologia e Farmacologia, Universidade Federal de Minas Gerais, Av. Presidente Antônio Carlos, 6627, Pampulha, CEP: 31270-901, Belo Horizonte, MG, Brazil
| | - Érica Leandro Marciano Vieira
- Campbell Family Mental Health Research Institute, Center of Addiction and Mental Health, 250 College Street, Toronto, ON M5T 1R8, Canada
| | - Antônio Carlos Pinheiro de Oliveira
- Laboratório de Neurofarmacologia, Departamento de Fisiologia e Farmacologia, Universidade Federal de Minas Gerais, Av. Presidente Antônio Carlos, 6627, Pampulha, CEP: 31270-901, Belo Horizonte, MG, Brazil
| | - Antônio Lúcio Teixeira
- Departament of Psychiatry and Behavioral Science McGovern School, Behavioral and Biomedical Sciences Building (BBSB), The University of Texas Health Science Center, 941 East Road, Houston, TX 77054, United States of America
| | - Aline Silva de Miranda
- Laboratório de Neurobiologia, Departamento de Morfologia, Universidade Federal de Minas Gerais, Av. Presidente Antônio Carlos, 6627, Pampulha, CEP: 31270-901, Belo Horizonte, MG, Brazil
| | - Aristóbolo Mendes da Silva
- Laboratório de Genes Inflamatórios, Departamento de Morfologia, Universidade Federal de Minas Gerais, Av. Presidente Antônio Carlos, 6627, Pampulha, CEP: 31270-901, Belo Horizonte, MG, Brazil
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Yao T, He J, Cui Z, Wang R, Bao K, Huang Y, Wang R, Liu T. Central 5-HTR2C in the Control of Metabolic Homeostasis. Front Endocrinol (Lausanne) 2021; 12:694204. [PMID: 34367066 PMCID: PMC8334728 DOI: 10.3389/fendo.2021.694204] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 07/06/2021] [Indexed: 11/29/2022] Open
Abstract
The 5-hydroxytryptamine 2C receptor (5-HTR2C) is a class G protein-coupled receptor (GPCR) enriched in the hypothalamus and the brain stem, where it has been shown to regulate energy homeostasis, including feeding and glucose metabolism. Accordingly, 5-HTR2C has been the target of several anti-obesity drugs, though the associated side effects greatly curbed their clinical applications. Dissecting the specific neural circuits of 5-HTR2C-expressing neurons and the detailed molecular pathways of 5-HTR2C signaling in metabolic regulation will help to develop better therapeutic strategies towards metabolic disorders. In this review, we introduced the regulatory role of 5-HTR2C in feeding behavior and glucose metabolism, with particular focus on the molecular pathways, neural network, and its interaction with other metabolic hormones, such as leptin, ghrelin, insulin, and estrogens. Moreover, the latest progress in the clinical research on 5-HTR2C agonists was also discussed.
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Affiliation(s)
- Ting Yao
- School of Kinesiology, Shanghai University of Sport, Shanghai, China
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi’an Jiaotong University School of Medicine, Xi’an, China
- *Correspondence: Ting Yao, ; Ru Wang, ; Tiemin Liu,
| | - Jiehui He
- School of Life Sciences, Fudan University, Shanghai, China
| | - Zhicheng Cui
- School of Life Sciences, Fudan University, Shanghai, China
| | - Ruwen Wang
- School of Kinesiology, Shanghai University of Sport, Shanghai, China
| | - Kaixuan Bao
- Human Phenome Institute, Fudan University, Shanghai, China
| | - Yiru Huang
- School of Life Sciences, Fudan University, Shanghai, China
| | - Ru Wang
- School of Kinesiology, Shanghai University of Sport, Shanghai, China
- *Correspondence: Ting Yao, ; Ru Wang, ; Tiemin Liu,
| | - Tiemin Liu
- School of Life Sciences, Fudan University, Shanghai, China
- Human Phenome Institute, Fudan University, Shanghai, China
- State Key Laboratory of Genetic Engineering, Fudan University, Shanghai, China
- State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing, China
- *Correspondence: Ting Yao, ; Ru Wang, ; Tiemin Liu,
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Higgins GA, Fletcher PJ, Shanahan WR. Lorcaserin: A review of its preclinical and clinical pharmacology and therapeutic potential. Pharmacol Ther 2020; 205:107417. [DOI: 10.1016/j.pharmthera.2019.107417] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Accepted: 09/30/2019] [Indexed: 12/17/2022]
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Silenieks LB, Carroll NK, Van Niekerk A, Van Niekerk E, Taylor C, Upton N, Higgins GA. Evaluation of Selective 5-HT 2C Agonists in Acute Seizure Models. ACS Chem Neurosci 2019; 10:3284-3295. [PMID: 31082204 DOI: 10.1021/acschemneuro.8b00739] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The 5-HT releaser/reuptake inhibitor fenfluramine has been recently reported to provide benefit as an adjunctive treatment for Dravet and Lennox-Gastaut syndromes, two types of severe childhood epilepsy. Despite its enhancement of 5-HT function, many effects of fenfluramine have been demonstrated to be dependent on 5-HT2C receptor activation, suggesting that 5-HT2C receptor activation may have an anticonvulsant property. The present study was designed to evaluate fenfluramine and 5-HT agonists of varying 5-HT2C agonist selectivity, the relatively nonselective mCPP and Ro 60-0175, and the selective 5-HT2C agonists lorcaserin and CP-809101 across a variety of acute seizure tests conducted in adult rats and mice, which have been instrumental in identifying the majority of clinically efficacious antiepileptic drugs. Tests included the maximal electroshock seizure (MES), MES threshold, and 6 Hz electrical convulsive seizure models and the chemoconvulsant pentylenetetrazole test. The effect of mCPP, lorcaserin, and CP-809101 against electrically evoked seizures in amygdala kindled rats was also investigated. Overall, at doses known to interact with 5-HT2CR, there was no clear class-related effect of these agonists in any test. The only notable antiseizure effect of fenfluramine was inhibition of MES-induced tonic seizures in the rat. The current preclinical studies using the classical acute seizure tests and an amygdala kindling model do not identify a reliable antiseizure effect of fenfluramine, an agent now used in the treatment of human epilepsies, including Dravet syndrome and Lennox-Gastaut syndrome. Given the nature of these epilepsies, early life and/or genetic models may have better construct validity and be more appropriate for further study.
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Affiliation(s)
- Leonardo B. Silenieks
- Intervivo Solutions Inc, Toronto, ON M5A 4K2, Canada
- Vivocore, Toronto, ON N1M 2W4, Canada
| | | | | | | | | | - Neil Upton
- Transpharmation Ltd, London NW10NH, United Kingdom
| | - Guy A. Higgins
- Intervivo Solutions Inc, Toronto, ON M5A 4K2, Canada
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON ON M5S, Canada
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Chagraoui A, Whitestone S, Baassiri L, Manem J, Di Giovanni G, De Deurwaerdère P. Neurochemical impact of the 5-HT2C receptor agonist WAY-163909 on monoamine tissue content in the rat brain. Neurochem Int 2019; 124:245-255. [DOI: 10.1016/j.neuint.2019.01.019] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 01/13/2019] [Accepted: 01/22/2019] [Indexed: 01/08/2023]
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Di Giovanni G, De Deurwaerdère P. TCB-2 [(7R)-3-bromo-2, 5-dimethoxy-bicyclo[4.2.0]octa-1,3,5-trien-7-yl]methanamine]: A hallucinogenic drug, a selective 5-HT 2A receptor pharmacological tool, or none of the above? Neuropharmacology 2017; 142:20-29. [PMID: 28987938 DOI: 10.1016/j.neuropharm.2017.10.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2017] [Revised: 09/14/2017] [Accepted: 10/03/2017] [Indexed: 01/28/2023]
Abstract
The development of 5-HT2A receptor agonists has been considerably marginalized since the demonstration that the tryptaminergic drugs, LSD and psilocybin, or the phenylakylamine drugs, mescaline and DOI, exert their hallucinogenic properties via the stimulation of 5-HT2A receptors. Nonetheless, the ability of drugs to stimulate 5-HT2A receptors is not necessarily associated with psychedelic experience and the hallucinogenic properties are still not understood. Several studies have increased interest in stimulating 5-HT2A receptors in various CNS diseases. (7R)-3-bromo-2, 5-dimethoxy-bicyclo[4.2.0]octa-1,3,5-trien-7-yl]methanamine (TCB-2) which was synthetized in 2006 presents a high affinity with human and rat 5-HT2A receptors. Its main feature of interest is that it preferentially stimulates the phospholipase C and not phospholipase A2 pathway, which is at variance with several hallucinogenic drugs. Preference for TCB-2 has increased in preclinical studies and it exhibits subtle differences compared to DOI or LSD in some molecular, cellular and behavioral studies. The purpose of this review is to take a position on the use of TCB-2 as a pharmacological tool. A careful reading of the literature has revealed that the suspected hallucinogenic properties of TCB-2 cannot firmly be ascertained while its pharmacological profile is unknown and likely not selective at 5-HT2A receptors. This article is part of the Special Issue entitled 'Psychedelics: New Doors, Altered Perceptions'.
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Affiliation(s)
- Giuseppe Di Giovanni
- Department of Physiology & Biochemistry, Faculty of Medicine and Surgery, University of Malta, Malta; Neuroscience Division, School of Biosciences, Cardiff University, Cardiff, UK.
| | - Philippe De Deurwaerdère
- Centre National de la Recherche Scientifique (Unité Mixte de Recherche 5287), 146 rue Léo Saignat, B.P.281, F-33000 Bordeaux Cedex, France
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7
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De Deurwaerdère P, Di Giovanni G. Serotonergic modulation of the activity of mesencephalic dopaminergic systems: Therapeutic implications. Prog Neurobiol 2016; 151:175-236. [PMID: 27013075 DOI: 10.1016/j.pneurobio.2016.03.004] [Citation(s) in RCA: 114] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Revised: 03/13/2016] [Accepted: 03/14/2016] [Indexed: 12/14/2022]
Abstract
Since their discovery in the mammalian brain, it has been apparent that serotonin (5-HT) and dopamine (DA) interactions play a key role in normal and abnormal behavior. Therefore, disclosure of this interaction could reveal important insights into the pathogenesis of various neuropsychiatric diseases including schizophrenia, depression and drug addiction or neurological conditions such as Parkinson's disease and Tourette's syndrome. Unfortunately, this interaction remains difficult to study for many reasons, including the rich and widespread innervations of 5-HT and DA in the brain, the plethora of 5-HT receptors and the release of co-transmitters by 5-HT and DA neurons. The purpose of this review is to present electrophysiological and biochemical data showing that endogenous 5-HT and pharmacological 5-HT ligands modify the mesencephalic DA systems' activity. 5-HT receptors may control DA neuron activity in a state-dependent and region-dependent manner. 5-HT controls the activity of DA neurons in a phasic and excitatory manner, except for the control exerted by 5-HT2C receptors which appears to also be tonically and/or constitutively inhibitory. The functional interaction between the two monoamines will also be discussed in view of the mechanism of action of antidepressants, antipsychotics, anti-Parkinsonians and drugs of abuse.
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Affiliation(s)
- Philippe De Deurwaerdère
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5293, 33076 Bordeaux Cedex, France.
| | - Giuseppe Di Giovanni
- Department of Physiology & Biochemistry, Faculty of Medicine and Surgery, University of Malta, Malta; Neuroscience Division, School of Biosciences, Cardiff University, Cardiff, UK.
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Martin-Gronert MS, Stocker CJ, Wargent ET, Cripps RL, Garfield AS, Jovanovic Z, D'Agostino G, Yeo GSH, Cawthorne MA, Arch JRS, Heisler LK, Ozanne SE. 5-HT2A and 5-HT2C receptors as hypothalamic targets of developmental programming in male rats. Dis Model Mech 2016; 9:401-12. [PMID: 26769798 PMCID: PMC4852506 DOI: 10.1242/dmm.023903] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 01/07/2016] [Indexed: 12/11/2022] Open
Abstract
Although obesity is a global epidemic, the physiological mechanisms involved are not well understood. Recent advances reveal that susceptibility to obesity can be programmed by maternal and neonatal nutrition. Specifically, a maternal low-protein diet during pregnancy causes decreased intrauterine growth, rapid postnatal catch-up growth and an increased risk for diet-induced obesity. Given that the synthesis of the neurotransmitter 5-hydroxytryptamine (5-HT) is nutritionally regulated and 5-HT is a trophic factor, we hypothesised that maternal diet influences fetal 5-HT exposure, which then influences development of the central appetite network and the subsequent efficacy of 5-HT to control energy balance in later life. Consistent with our hypothesis, pregnant rats fed a low-protein diet exhibited elevated serum levels of 5-HT, which was also evident in the placenta and fetal brains at embryonic day 16.5. This increase was associated with reduced levels of 5-HT2CR, the primary 5-HT receptor influencing appetite, in the fetal, neonatal and adult hypothalamus. As expected, a reduction of 5-HT2CR was associated with impaired sensitivity to 5-HT-mediated appetite suppression in adulthood. 5-HT primarily achieves effects on appetite by 5-HT2CR stimulation of pro-opiomelanocortin (POMC) peptides within the arcuate nucleus of the hypothalamus (ARC). We show that 5-HT2ARs are also anatomically positioned to influence the activity of ARC POMC neurons and that mRNA encoding 5-HT2AR is increased in the hypothalamus ofin uterogrowth-restricted offspring that underwent rapid postnatal catch-up growth. Furthermore, these animals at 3 months of age are more sensitive to appetite suppression induced by 5-HT2AR agonists. These findings not only reveal a 5-HT-mediated mechanism underlying the programming of susceptibility to obesity, but also provide a promising means to correct it, by treatment with a 5-HT2AR agonist.
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Affiliation(s)
- Malgorzata S Martin-Gronert
- University of Cambridge, Metabolic Research Laboratories and MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK
| | - Claire J Stocker
- Clore Laboratory, Buckingham Institute for Translational Medicine, University of Buckingham, Hunter Street, Buckingham MK18 1EG, UK
| | - Edward T Wargent
- Clore Laboratory, Buckingham Institute for Translational Medicine, University of Buckingham, Hunter Street, Buckingham MK18 1EG, UK
| | - Roselle L Cripps
- University of Cambridge, Metabolic Research Laboratories and MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK
| | | | - Zorica Jovanovic
- University of Cambridge, Metabolic Research Laboratories and MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK
| | | | - Giles S H Yeo
- University of Cambridge, Metabolic Research Laboratories and MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK
| | - Michael A Cawthorne
- Clore Laboratory, Buckingham Institute for Translational Medicine, University of Buckingham, Hunter Street, Buckingham MK18 1EG, UK
| | - Jonathan R S Arch
- Clore Laboratory, Buckingham Institute for Translational Medicine, University of Buckingham, Hunter Street, Buckingham MK18 1EG, UK
| | - Lora K Heisler
- Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, UK
| | - Susan E Ozanne
- University of Cambridge, Metabolic Research Laboratories and MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK
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Di Giovanni G, De Deurwaerdère P. New therapeutic opportunities for 5-HT2C receptor ligands in neuropsychiatric disorders. Pharmacol Ther 2015; 157:125-62. [PMID: 26617215 DOI: 10.1016/j.pharmthera.2015.11.009] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The 5-HT2C receptor (R) displays a widespread distribution in the CNS and is involved in the action of 5-HT in all brain areas. Knowledge of its functional role in the CNS pathophysiology has been impaired for many years due to the lack of drugs capable of discriminating among 5-HT2R subtypes, and to a lesser extent to the 5-HT1B, 5-HT5, 5-HT6 and 5-HT7Rs. The situation has changed since the mid-90s due to the increased availability of new and selective synthesized compounds, the creation of 5-HT2C knock out mice, and the progress made in molecular biology. Many pharmacological classes of drugs including antipsychotics, antidepressants and anxiolytics display affinities toward 5-HT2CRs and new 5-HT2C ligands have been developed for various neuropsychiatric disorders. The 5-HT2CR is presumed to mediate tonic/constitutive and phasic controls on the activity of different central neurobiological networks. Preclinical data illustrate this complexity to a point that pharmaceutical companies developed either agonists or antagonists for the same disease. In order to better comprehend this complexity, this review will briefly describe the molecular pharmacology of 5-HT2CRs, as well as their cellular impacts in general, before addressing its central distribution in the mammalian brain. Thereafter, we review the preclinical efficacy of 5-HT2C ligands in numerous behavioral tests modeling human diseases, highlighting the multiple and competing actions of the 5-HT2CRs in neurobiological networks and monoaminergic systems. Notably, we will focus this evidence in the context of the physiopathology of psychiatric and neurological disorders including Parkinson's disease, levodopa-induced dyskinesia, and epilepsy.
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Affiliation(s)
- Giuseppe Di Giovanni
- Department of Physiology & Biochemistry, Faculty of Medicine and Surgery, University of Malta; Neuroscience Division, School of Biosciences, Cardiff University, Cardiff, UK.
| | - Philippe De Deurwaerdère
- Centre National de la Recherche Scientifique (Unité Mixte de Recherche 5293) 33076 Bordeaux Cedex, France.
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Schellekens H, De Francesco PN, Kandil D, Theeuwes WF, McCarthy T, van Oeffelen WEPA, Perelló M, Giblin L, Dinan TG, Cryan JF. Ghrelin's Orexigenic Effect Is Modulated via a Serotonin 2C Receptor Interaction. ACS Chem Neurosci 2015; 6:1186-97. [PMID: 25727097 DOI: 10.1021/cn500318q] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Understanding the intricate pathways that modulate appetite and subsequent food intake is of particular importance considering the rise in the incidence of obesity across the globe. The serotonergic system, specifically the 5-HT2C receptor, has been shown to be of critical importance in the regulation of appetite and satiety. The GHS-R1a receptor is another key receptor that is well-known for its role in the homeostatic control of food intake and energy balance. We recently showed compelling evidence for an interaction between the GHS-R1a receptor and the 5-HT2C receptor in an in vitro cell line system heterologously expressing both receptors. Here, we investigated this interaction further. First, we show that the GHS-R1a/5-HT2C dimer-induced attenuation of calcium signaling is not due to coupling to GαS, as no increase in cAMP signaling is observed. Next, flow cytometry fluorescence resonance energy transfer (fcFRET) is used to further demonstrate the direct interaction between the GHS-R1a receptor and 5-HT2C receptor. In addition, we demonstrate colocalized expression of the 5-HT2C and GHS-R1a receptor in cultured primary hypothalamic and hippocampal rat neurons, supporting the biological relevance of a physiological interaction. Furthermore, we demonstrate that when 5-HT2C receptor signaling is blocked ghrelin's orexigenic effect is potentiated in vivo. In contrast, the specific 5-HT2C receptor agonist lorcaserin, recently approved for the treatment of obesity, attenuates ghrelin-induced food intake. This underscores the biological significance of our in vitro findings of 5-HT2C receptor-mediated attenuation of GHS-R1a receptor activity. Together, this study demonstrates, for the first time, that the GHS-R1a/5-HT2C receptor interaction translates into a biologically significant modulation of ghrelin's orexigenic effect. This data highlights the potential development of a combined GHS-R1a and 5-HT2C receptor treatment strategy in weight management.
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Affiliation(s)
| | - Pablo N. De Francesco
- Laboratory
of Neurophysiology, Multidisciplinary Institute of Cell Biology, National Scientific and Technical Research Council, La Plata, Argentina
| | | | | | | | | | - Mario Perelló
- Laboratory
of Neurophysiology, Multidisciplinary Institute of Cell Biology, National Scientific and Technical Research Council, La Plata, Argentina
| | - Linda Giblin
- Teagasc Food Research Centre, Moorepark, Fermoy, Co. Cork, Ireland
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Higgins GA, Fletcher PJ. Therapeutic Potential of 5-HT2C Receptor Agonists for Addictive Disorders. ACS Chem Neurosci 2015; 6:1071-88. [PMID: 25870913 DOI: 10.1021/acschemneuro.5b00025] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The neurotransmitter 5-hydroxytryptamine (5-HT; serotonin) has long been associated with the control of a variety of motivated behaviors, including feeding. Much of the evidence linking 5-HT and feeding behavior was obtained from studies of the effects of the 5-HT releaser (dex)fenfluramine in laboratory animals and humans. Recently, the selective 5-HT2C receptor agonist lorcaserin received FDA approval for the treatment of obesity. This review examines evidence to support the use of selective 5-HT2C receptor agonists as treatments for conditions beyond obesity, including substance abuse (particularly nicotine, psychostimulant, and alcohol dependence), obsessive compulsive, and excessive gambling disorder. Following a brief survey of the early literature supporting a role for 5-HT in modulating food and drug reinforcement, we propose that intrinsic differences between SSRI and serotonin releasers may have underestimated the value of serotonin-based pharmacotherapeutics to treat clinical forms of addictive behavior beyond obesity. We then highlight the critical involvement of the 5-HT2C receptor in mediating the effect of (dex)fenfluramine on feeding and body weight gain and the evidence that 5-HT2C receptor agonists reduce measures of drug reward and impulsivity. A recent report of lorcaserin efficacy in a smoking cessation trial further strengthens the idea that 5-HT2C receptor agonists may have potential as a treatment for addiction. This review was prepared as a contribution to the proceedings of the 11th International Society for Serotonin Research Meeting held in Hermanus, South Africa, July 9-12, 2014.
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Affiliation(s)
- Guy A. Higgins
- InterVivo Solutions Inc., 120 Carlton Street, Toronto, ON M5A
4K2, Canada
- Department of Pharmacology & Toxicology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Paul J. Fletcher
- Section of Biopsychology
and Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, 250 College Street, Toronto, ON M5T 1R8, Canada
- Departments of Psychiatry & Psychology, University of Toronto, Toronto, ON M5T 1R8, Canada
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Bezzina G, Body S, Cheung THC, Hampson CL, Bradshaw CM, Glennon JC, Szabadi E. Evidence for a role of 5-HT2C receptors in the motor aspects of performance, but not the efficacy of food reinforcers, in a progressive ratio schedule. Psychopharmacology (Berl) 2015; 232:699-711. [PMID: 25134499 DOI: 10.1007/s00213-014-3700-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2014] [Accepted: 07/28/2014] [Indexed: 12/25/2022]
Abstract
RATIONALE 5-Hydroxytryptamine2C (5-HT2C) receptor agonists reduce the breakpoint in progressive ratio schedules of reinforcement, an effect that has been attributed to a decrease of the efficacy of positive reinforcers. However, a reduction of the breakpoint may also reflect motor impairment. Mathematical models can help to differentiate between these processes. OBJECTIVE The effects of the 5-HT2C receptor agonist Ro-600175 ((αS)-6-chloro-5-fluoro-α-methyl-1H-indole-1-ethanamine) and the non-selective 5-HT receptor agonist 1-(m-chlorophenyl)piperazine (mCPP) on rats' performance on a progressive ratio schedule maintained by food pellet reinforcers were assessed using a model derived from Killeen's Behav Brain Sci 17:105-172, 1994 general theory of schedule-controlled behaviour, 'mathematical principles of reinforcement'. METHOD Rats were trained under the progressive ratio schedule, and running and overall response rates in successive ratios were analysed using the model. The effects of the agonists on estimates of the model's parameters, and the sensitivity of these effects to selective antagonists, were examined. RESULTS Ro-600175 and mCPP reduced the breakpoint. Neither agonist significantly affected a (the parameter expressing incentive value), but both agonists increased δ (the parameter expressing minimum response time). The effects of both agonists could be attenuated by the selective 5-HT2C receptor antagonist SB-242084 (6-chloro-5-methyl-N-{6-[(2-methylpyridin-3-yl)oxy]pyridin-3-yl}indoline-1-carboxamide). The effect of mCPP was not altered by isamoltane, a selective 5-HT1B receptor antagonist, or MDL-100907 ((±)2,3-dimethoxyphenyl-1-(2-(4-piperidine)methanol)), a selective 5-HT2A receptor antagonist. CONCLUSIONS The results are consistent with the hypothesis that the effect of the 5-HT2C receptor agonists on progressive ratio schedule performance is mediated by an impairment of motor capacity rather than by a reduction of the incentive value of the food reinforcer.
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Affiliation(s)
- G Bezzina
- Psychopharmacology Section, Division of Psychiatry, University of Nottingham, Medical School, Nottingham, NG7 2UH, UK
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Schellekens H, Nongonierma AB, Clarke G, van Oeffelen WE, FitzGerald RJ, Dinan TG, Cryan JF. Milk protein-derived peptides induce 5-HT2C-mediated satiety in vivo. Int Dairy J 2014. [DOI: 10.1016/j.idairyj.2014.04.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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14
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Orban G, Bombardi C, Marino Gammazza A, Colangeli R, Pierucci M, Pomara C, Pessia M, Bucchieri F, Arcangelo B, Smolders I, De Deurwaerdère P, Di Giovanni G. Role(s) of the 5-HT2C receptor in the development of maximal dentate activation in the hippocampus of anesthetized rats. CNS Neurosci Ther 2014; 20:651-61. [PMID: 24935789 PMCID: PMC6493041 DOI: 10.1111/cns.12285] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 04/23/2014] [Accepted: 04/26/2014] [Indexed: 11/29/2022] Open
Abstract
AIMS Substantial evidence indicates that 5-HT2C receptors are involved in the control of neuronal network excitability and in seizure pathophysiology. Here, we have addressed the relatively unexplored relationship between temporal lobe epilepsy (TLE), the most frequent type of intractable epilepsy, and 5-HT2CRs. METHODS In this study, we investigated this issue using a model of partial complex (limbic) seizures in urethane-anesthetized rat, based on the phenomenon of maximal dentate activation (MDA) using 5-HT2C compounds, electrophysiology, immunohistochemistry, and western blotting techniques. RESULTS The 5-HT2C agonists mCPP (1 mg/kg, i.p) and lorcaserin (3 mg/kg, i.p), but not RO60-0175 (1-3 mg/kg i.p.), were antiepileptogenic reducing the MDA response duration. The selective 5-HT2C antagonist SB242084 (2 mg/kg, i.p) unveiled antiepileptogenic effects of RO60-0175 (3 mg/kg, i.p) but did not alter those induced by mCPP and lorcaserin. Compared with control rats, electrically stimulated rats showed an increase in glutamic acid decarboxylase levels and a heterogeneous decrease in 5-HT2CR immunoreactivity in different hippocampal areas. CONCLUSIONS In our animal model of TLE, mCPP and lorcaserin were anticonvulsant; likely acting on receptor subtypes other than 5-HT2C. Epileptogenesis induced early adaptive changes and reorganization in the 5-HT2CR and GABA systems.
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Affiliation(s)
- Gergely Orban
- Dipartimento di Biomedicina Sperimentale e Neuroscienze ClinicheUniversità degli Studi di PalermoPalermoItaly
- Istituto Euro‐Mediterraneo di Scienza e Tecnologia (IEMEST)PalermoItaly
| | - Cristiano Bombardi
- Department of Veterinary Medical ScienceUniversity of BolognaBolognaItaly
| | - Antonella Marino Gammazza
- Dipartimento di Biomedicina Sperimentale e Neuroscienze ClinicheUniversità degli Studi di PalermoPalermoItaly
- Istituto Euro‐Mediterraneo di Scienza e Tecnologia (IEMEST)PalermoItaly
| | - Roberto Colangeli
- Department of Physiology and BiochemistryUniversity of MaltaMsidaMalta
| | - Massimo Pierucci
- Istituto Euro‐Mediterraneo di Scienza e Tecnologia (IEMEST)PalermoItaly
- Department of Physiology and BiochemistryUniversity of MaltaMsidaMalta
| | - Cristoforo Pomara
- Department of AnatomyFaculty of Medicine and SurgeryUniversity of MaltaMsidaMalta
- Department of Forensic PathologyUniversity of FoggiaFoggiaItaly
| | - Mauro Pessia
- Department of Internal MedicineSection of Human PhysiologyUniversity of PerugiaPerugiaItaly
| | - Fabio Bucchieri
- Dipartimento di Biomedicina Sperimentale e Neuroscienze ClinicheUniversità degli Studi di PalermoPalermoItaly
- Istituto Euro‐Mediterraneo di Scienza e Tecnologia (IEMEST)PalermoItaly
| | - Benigno Arcangelo
- Dipartimento di Biomedicina Sperimentale e Neuroscienze ClinicheUniversità degli Studi di PalermoPalermoItaly
| | - Ilse Smolders
- Center for Neurosciences C4NVrije Universiteit BrusselBrusselsBelgium
| | | | - Giuseppe Di Giovanni
- Istituto Euro‐Mediterraneo di Scienza e Tecnologia (IEMEST)PalermoItaly
- Department of Physiology and BiochemistryUniversity of MaltaMsidaMalta
- School of BiosciencesCardiff UniversityCardiffUK
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Role of 5-HT2C receptors in the enhancement of c-Fos expression induced by a 5-HT2B/2C inverse agonist and 5-HT2 agonists in the rat basal ganglia. Exp Brain Res 2013; 230:525-35. [DOI: 10.1007/s00221-013-3562-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2013] [Accepted: 05/04/2013] [Indexed: 10/26/2022]
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16
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Multiple controls exerted by 5-HT2C receptors upon basal ganglia function: from physiology to pathophysiology. Exp Brain Res 2013; 230:477-511. [PMID: 23615975 DOI: 10.1007/s00221-013-3508-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Accepted: 03/28/2013] [Indexed: 10/26/2022]
Abstract
Serotonin2C (5-HT2C) receptors are expressed in the basal ganglia, a group of subcortical structures involved in the control of motor behaviour, mood and cognition. These receptors are mediating the effects of 5-HT throughout different brain areas via projections originating from midbrain raphe nuclei. A growing interest has been focusing on the function of 5-HT2C receptors in the basal ganglia because they may be involved in various diseases of basal ganglia function notably those associated with chronic impairment of dopaminergic transmission. 5-HT2C receptors act on numerous types of neurons in the basal ganglia, including dopaminergic, GABAergic, glutamatergic or cholinergic cells. Perhaps inherent to their peculiar molecular properties, the modality of controls exerted by 5-HT2C receptors over these cell populations can be phasic, tonic (dependent on the 5-HT tone) or constitutive (a spontaneous activity without the presence of the ligand). These controls are functionally organized in the basal ganglia: they are mainly localized in the input structures and preferentially distributed in the limbic/associative territories of the basal ganglia. The nature of these controls is modified in neuropsychiatric conditions such as Parkinson's disease, tardive dyskinesia or addiction. Most of the available data indicate that the function of 5-HT2C receptor is enhanced in cases of chronic alterations of dopamine neurotransmission. The review illustrates that 5-HT2C receptors play a role in maintaining continuous controls over the basal ganglia via multiple diverse actions. We will discuss their interest for treatments aimed at ameliorating current pharmacotherapies in schizophrenia, Parkinson's disease or drugs abuse.
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Nongonierma AB, Schellekens H, Dinan TG, Cryan JF, FitzGerald RJ. Milk protein hydrolysates activate 5-HT2C serotonin receptors: influence of the starting substrate and isolation of bioactive fractions. Food Funct 2013; 4:728-37. [DOI: 10.1039/c3fo30309h] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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18
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Canal CE, Morgan D. Head-twitch response in rodents induced by the hallucinogen 2,5-dimethoxy-4-iodoamphetamine: a comprehensive history, a re-evaluation of mechanisms, and its utility as a model. Drug Test Anal 2012; 4:556-76. [PMID: 22517680 DOI: 10.1002/dta.1333] [Citation(s) in RCA: 134] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2011] [Revised: 01/09/2012] [Accepted: 01/10/2012] [Indexed: 11/06/2022]
Abstract
Two primary animal models persist for assessing hallucinogenic potential of novel compounds and for examining the pharmacological and neurobiological substrates underlying the actions of classical hallucinogens, the two-lever drug discrimination procedure and the drug-induced head-twitch response (HTR) in rodents. The substituted amphetamine hallucinogen, serotonin 2 (5-HT(2) ) receptor agonist, 2,5-dimethoxy-4-iodoamphetamine (DOI) has emerged as the most popular pharmacological tool used in HTR studies of hallucinogens. Synthesizing classic, recent, and relatively overlooked findings, addressing ostensibly conflicting observations, and considering contemporary theories in receptor and behavioural pharmacology, this review provides an up-to-date and comprehensive synopsis of DOI and the HTR model, from neural mechanisms to utility for understanding psychiatric diseases. Also presented is support for the argument that, although both the two-lever drug discrimination and the HTR models in rodents are useful for uncovering receptors, interacting proteins, intracellular signalling pathways, and neurochemical processes affected by DOI and related classical hallucinogens, results from both models suggest they are not reporting hallucinogenic experiences in animals.
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Affiliation(s)
- Clint E Canal
- Department of Medicinal Chemistry, College of Pharmacy, University of Florida, Gainesville, FL 32610, USA.
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19
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Schellekens H, Clarke G, Jeffery IB, Dinan TG, Cryan JF. Dynamic 5-HT2C receptor editing in a mouse model of obesity. PLoS One 2012; 7:e32266. [PMID: 22448217 PMCID: PMC3308946 DOI: 10.1371/journal.pone.0032266] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Accepted: 01/25/2012] [Indexed: 11/25/2022] Open
Abstract
The central serotonergic signalling system has been shown to play an important role in appetite control and the regulation of food intake. Serotonin exerts its anorectic effects mainly through the 5-HT(1B), 5-HT(2C) and 5-HT(6) receptors and these are therefore receiving increasing attention as principal pharmacotherapeutic targets for the treatment of obesity. The 5-HT(2C) receptor has the distinctive ability to be modified by posttranscriptional RNA editing on 5 nucleotide positions (A, B, C, D, E), having an overall decreased receptor function. Recently, it has been shown that feeding behaviour and fat mass are altered when the 5-HT(2C) receptor RNA is fully edited, suggesting a potential role for 5-HT(2C) editing in obesity. The present studies investigate the expression of serotonin receptors involved in central regulation of food intake, appetite and energy expenditure, with particular focus on the level of 5-HT(2C) receptor editing. Using a leptin-deficient mouse model of obesity (ob/ob), we show increased hypothalamic 5-HT(1A) receptor expression as well as increased hippocampal 5-HT(1A), 5-HT(1B), and 5-HT(6) receptor mRNA expression in obese mice compared to lean control mice. An increase in full-length 5-HT(2C) expression, depending on time of day, as well as differences in 5-HT(2C) receptor editing were found, independent of changes in total 5-HT(2C) receptor mRNA expression. This suggests that a dynamic regulation exists of the appetite-suppressing effects of the 5-HT(2C) receptor in both the hypothalamus and the hippocampus in the ob/ob mice model of obesity. The differential 5-HT(1A), 5-HT(1B) and 5-HT(6) receptor expression and altered 5-HT(2C) receptor editing profile reported here is poised to have important consequences for the development of novel anti-obesity therapies.
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Affiliation(s)
- Harriët Schellekens
- Food for Health Ireland, University College Cork, Cork, Ireland
- School of Pharmacy, University College Cork, Cork, Ireland
| | - Gerard Clarke
- Laboratory of Neurogastroenterology, Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland
- Department of Psychiatry, University College Cork, Cork, Ireland
| | - Ian B. Jeffery
- Department of Microbiology, University College Cork, Cork, Ireland
| | - Timothy G. Dinan
- Food for Health Ireland, University College Cork, Cork, Ireland
- Laboratory of Neurogastroenterology, Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland
- Department of Psychiatry, University College Cork, Cork, Ireland
| | - John F. Cryan
- Food for Health Ireland, University College Cork, Cork, Ireland
- Laboratory of Neurogastroenterology, Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
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De Deurwaerdère P, Mignon L, Chesselet MF. Physiological and Pathophysiological Aspects of 5-HT2c Receptors in Basal Ganglia. 5-HT2C RECEPTORS IN THE PATHOPHYSIOLOGY OF CNS DISEASE 2011. [DOI: 10.1007/978-1-60761-941-3_18] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
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Abstract
Studies employing animal models of attention-deficit/hyperactivity disorder (ADHD) present clear inherent advantages over human studies. Animal models are invaluable tools for the study of underlying neurochemical, neuropathological and genetic alterations that cause ADHD, because they allow relatively fast, rigorous hypothesis testing and invasive manipulations as well as selective breeding. Moreover, especially for ADHD, animal models with good predictive validity would allow the assessment of potential new therapeutics. In this chapter, we describe and comment on the most frequently used animal models of ADHD that have been created by genetic, neurochemical and physical alterations in rodents. We then discuss that an emerging and promising direction of the field is the analysis of individual behavioural differences among a normal population of animals. Subjects presenting extreme characteristics related to ADHD can be studied, thereby avoiding some of the problems that are found in other models, such as functional recovery and unnecessary assumptions about aetiology. This approach is justified by the theoretical need to consider human ADHD as the extreme part of a spectrum of characteristics that are distributed normally in the general population, as opposed to the predominant view of ADHD as a separate pathological category.
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Affiliation(s)
- A Bari
- Department of Experimental Psychology, Behavioural and Clinical Neuroscience Institute, University of Cambridge, Downing Street, Cambridge, CB2 3EB, UK,
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22
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Huang M, Dai J, Meltzer HY. 5-HT(2A) and 5-HT(2C) receptor stimulation are differentially involved in the cortical dopamine efflux-Studied in 5-HT(2A) and 5-HT(2C) genetic mutant mice. Eur J Pharmacol 2010; 652:40-5. [PMID: 21118683 DOI: 10.1016/j.ejphar.2010.10.094] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2010] [Revised: 10/13/2010] [Accepted: 10/31/2010] [Indexed: 02/03/2023]
Abstract
Both 5-HT(2A) and 5-HT(2C) receptors modulate cortical dopamine efflux, but in opposite directions. We have now compared the ability of the three 5-HT(2A/2C) receptor agonists, DOI (R(-)-2,5-dimethoxy-4-iodoamphetamine), mCPP (meta-chlorophenylpiperazine) and MK-212 (6-Chloro-2-(piperazinyl) pyrazine), to modulate cortical dopamine efflux in 5-HT(2A) and 5-HT(2C) genetic mutant mice. In the 5-HT(2A) mice, the preferential 5-HT(2A) receptor agonist DOI (2.5mg/kg, s.c.) induced a slight but significant increase in cortical dopamine efflux only in the wild type (WT) mice; MK-212 (2.5mg/kg) reduced dopamine efflux in both WT and receptor knockout (KO) mice; moreover, MCPP, 2.5mg/kg, had no effect in either types. In 5-HT(2C) mice, DOI increased dopamine efflux in both types; while MK-212 decreased dopamine efflux in the WT, but not the receptor KO mice. These results provide new evidence that 5-HT(2A) receptor stimulation enhances and 5-HT(2C) receptor stimulation inhibits cortical dopamine efflux, and suggest the effects of DOI, MK-212 and mCPP on the cortical dopamine efflux are due to their different abilities on 5-HT(2A) and 5-HT(2C) receptors stimulation. Of these three agents, only DOI, the more selective 5-HT(2A) receptor agonist, is hallucinogenic. The absence of hallucinations with mCPP may be due to its relatively more potent 5-HT(2C) receptor agonist effect, inhibiting the ability of mCPP to enhance dopamine efflux in cortical and perhaps limbic regions as well. The present data provide additional evidence that hallucinations are due, in part, to 5-HT(2A) rather than 5-HT(2C) receptor stimulation. These findings suggest that 5-HT(2C) receptor agonists may be useful as antipsychotics, consistent with previous suggestions.
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Affiliation(s)
- Mei Huang
- Division of Psychopharcology, Department of Psychiatry, Vanderbilt University School of Medicine, TN, USA
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23
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Fletcher PJ, Sinyard J, Higgins GA. Genetic and pharmacological evidence that 5-HT2C receptor activation, but not inhibition, affects motivation to feed under a progressive ratio schedule of reinforcement. Pharmacol Biochem Behav 2010; 97:170-8. [PMID: 20624416 DOI: 10.1016/j.pbb.2010.07.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2010] [Revised: 06/25/2010] [Accepted: 07/05/2010] [Indexed: 12/27/2022]
Abstract
Previous work showed that 5-HT(2C) receptor agonists reduce cocaine self-administration on a progressive ratio (PR) schedule of reinforcement, whereas a 5-HT(2C) receptor antagonist enhances responding for cocaine. The present experiments examined the effects of Ro60-0175 (5-HT(2C) agonist) and SB242084 (5-HT(2C) receptor antagonist) in rats on responding for food on a PR schedule; responding was also determined in mice lacking functional 5-HT(2C) receptors. In food-restricted rats, lever pressing reinforced by regular food pellets or sucrose pellets was reduced by Ro60-0175. This effect was blocked by SB242084, and was absent in mice lacking functional 5-HT(2C) receptors. A number of studies examined the effects of SB242084 on responding for food under a variety of conditions. These included manipulation of food type (regular pellets versus sucrose pellets), nutritional status of the animals (food restriction versus no restriction), and rate of progression of the increase in ratio requirements on the PR schedule. In all cases there was no evidence of enhanced responding for food by SB242084. Mice lacking functional 5-HT(2C) receptors did not differ from wildtype mice in responding for food in either food-restricted or non-restricted states. The effects of Ro60-0175 are consistent with its effects on food consumption and motivation to self-administer cocaine. Unlike their effects on cocaine self-administration, pharmacological blockade of 5-HT(2C) receptors, and genetic disruption of 5-HT(2C) receptor function do not alter the motivation to respond for food. Because the 5-HT(2C) receptor exerts a modulatory effect on dopamine function, the differential effects of reduced 5-HT(2C) receptor mediated transmission on responding for food versus cocaine may relate to a differential role of this neurotransmitter in mediating these two behaviours.
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Affiliation(s)
- Paul J Fletcher
- Section of Biopsychology, Centre for Addiction and Mental Health, Toronto, Ontario, Canada.
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Fletcher PJ, Tampakeras M, Sinyard J, Slassi A, Isaac M, Higgins GA. Characterizing the effects of 5-HT2C receptor ligands on motor activity and feeding behaviour in 5-HT2C receptor knockout mice. Neuropharmacology 2009; 57:259-67. [DOI: 10.1016/j.neuropharm.2009.05.011] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2007] [Revised: 05/22/2009] [Accepted: 05/27/2009] [Indexed: 11/28/2022]
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Kimura A, Stevenson PL, Carter RN, Maccoll G, French KL, Simons JP, Al-Shawi R, Kelly V, Chapman KE, Holmes MC. Overexpression of 5-HT2C receptors in forebrain leads to elevated anxiety and hypoactivity. Eur J Neurosci 2009; 30:299-306. [PMID: 19614978 PMCID: PMC2777260 DOI: 10.1111/j.1460-9568.2009.06831.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2009] [Revised: 05/08/2009] [Accepted: 06/04/2009] [Indexed: 01/13/2023]
Abstract
The 5-HT(2C) receptor has been implicated in mood and eating disorders. In general, it is accepted that 5-HT(2C) receptor agonists increase anxiety behaviours and induce hypophagia. However, pharmacological analysis of the roles of these receptors is hampered by the lack of selective ligands and the complex regulation of receptor isoforms and expression levels. Therefore, the exact role of 5-HT(2C) receptors in mood disorders remain controversial, some suggesting agonists and others suggesting antagonists may be efficacious antidepressants, while there is general agreement that antagonists are beneficial anxiolytics. In order to test the hypothesis that increased 5-HT(2C) receptor expression, and thus increased 5-HT(2C) receptor signalling, is causative in mood disorders, we have undertaken a transgenic approach, directly altering the 5-HT(2C) receptor number in the forebrain and evaluating the consequences on behaviour. Transgenic mice overexpressing 5-HT(2C) receptors under the control of the CaMKIIalpha promoter (C2CR mice) have elevated 5-HT(2C) receptor mRNA levels in cerebral cortex and limbic areas (including the hippocampus and amygdala), but normal levels in the hypothalamus, resulting in > 100% increase in the number of 5-HT(2C) ligand binding sites in the forebrain. The C2CR mice show increased anxiety-like behaviour in the elevated plus-maze, decreased wheel-running behaviour and reduced activity in a novel environment. These behaviours were observed in the C2CR mice without stimulation by exogenous ligands. Our findings support a role for 5-HT(2C) receptor signalling in anxiety disorders. The C2CR mouse model offers a novel and effective approach for studying disorders associated with 5-HT(2C) receptors.
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Affiliation(s)
- Atsuko Kimura
- Endocrinology Unit, Centre for Cardiovascular Science, University of Edinburgh, Queen's Medical Research Institute, Edinburgh, Scotland.
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Mannoury La Cour C, Chaput C, Touzard M, Millan MJ. An immunocapture/scintillation proximity analysis of G alpha q/11 activation by native serotonin (5-HT)2A receptors in rat cortex: blockade by clozapine and mirtazapine. Synapse 2009; 63:95-105. [PMID: 19016481 DOI: 10.1002/syn.20587] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Though transduction mechanisms recruited by heterologously expressed 5-HT(2A) receptors have been extensively studied, their interaction with specific subtypes of G-protein remains to be directly evaluated in cerebral tissue. Herein, as shown by an immunocapture/scintillation proximity analysis, 5-HT, the prototypical 5-HT(2A) agonist, DOI, and Ro60,0175 all enhanced [(35)S]GTPgammaS binding to G alpha q/11 in rat cortex with pEC(50) values of 6.22, 7.24 and 6.35, respectively. No activation of G o or G s/olf was seen at equivalent concentrations of DOI. Stimulation of G alpha q/11 by 5-HT (30 microM) and DOI (30 microM) was abolished by the selective 5-HT(2A) vs. 5-HT(2C)/5-HT(2B) antagonists, ketanserin (pK(B) values of 9.11 and 8.88, respectively) and MDL100,907 (9.82 and 9.68). By contrast, 5-HT-induced [(35)S]GTPgammaS binding to G alpha q/11 was only weakly inhibited by the preferential 5-HT(2C) receptor antagonists, RS102,221 (6.94) and SB242,084 (7.39), and the preferential 5-HT(2B) receptor antagonist, LY266,097 (6.66). The antipsychotic, clozapine, which had marked affinity for 5-HT(2A) receptors, blocked the recruitment of G alpha q/11 by 5-HT and DOI with pK(B) values of 8.54 and 8.14, respectively. Its actions were mimicked by the "atypical" antidepressant and 5-HT(2A) receptor antagonist, mirtazapine, which likewise blocked 5-HT and DOI-induced G alpha q/11 protein activation with pK(B) values of 7.90 and 7.76, respectively. In conclusion, by use of an immunocapture/scintillation proximity strategy, this study shows that native 5-HT(2A) receptors in rat frontal cortex specifically recruit G alpha q/11 and that this action is blocked by clozapine and mirtazapine. Quantification of 5-HT(2A) receptor-mediated G alpha q/11 activation in frontal cortex should prove instructive in characterizing the actions of diverse classes of psychotropic agent.
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Affiliation(s)
- C Mannoury La Cour
- Institut de Recherche Servier, Psychopharmacology Department, 125 Chemin de Ronde, 78290 Croissy sur Seine, France.
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Brommage R, Desai U, Revelli JP, Donoviel DB, Fontenot GK, Dacosta CM, Smith DD, Kirkpatrick LL, Coker KJ, Donoviel MS, Eberhart DE, Holt KH, Kelly MR, Paradee WJ, Philips AV, Platt KA, Suwanichkul A, Hansen GM, Sands AT, Zambrowicz BP, Powell DR. High-throughput screening of mouse knockout lines identifies true lean and obese phenotypes. Obesity (Silver Spring) 2008; 16:2362-7. [PMID: 18719666 DOI: 10.1038/oby.2008.361] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
We developed a high-throughput approach to knockout (KO) and phenotype mouse orthologs of the 5,000 potential drug targets in the human genome. As part of the phenotypic screen, dual-energy X-ray absorptiometry (DXA) technology estimates body-fat stores in eight KO and four wild-type (WT) littermate chow-fed mice from each line. Normalized % body fat (nBF) (mean KO % body fat/mean WT littermate % body fat) values from the first 2322 lines with viable KO mice at 14 weeks of age showed a normal distribution. We chose to determine how well this screen identifies body-fat phenotypes by selecting 13 of these 2322 KO lines to serve as benchmarks based on their published lean or obese phenotype on a chow diet. The nBF values for the eight benchmark KO lines with a lean phenotype were > or =1 s.d. below the mean for seven (perilipin, SCD1, CB1, MCH1R, PTP1B, GPAT1, PIP5K2B) but close to the mean for NPY Y4R. The nBF values for the five benchmark KO lines with an obese phenotype were >2 s.d. above the mean for four (MC4R, MC3R, BRS3, translin) but close to the mean for 5HT2cR. This screen also identifies novel body-fat phenotypes as exemplified by the obese kinase suppressor of ras 2 (KSR2) KO mice. These body-fat phenotypes were confirmed upon studying additional cohorts of mice for KSR2 and all 13 benchmark KO lines. This simple and cost-effective screen appears capable of identifying genes with a role in regulating mammalian body fat.
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Monck NJT, Kennett GA. 5-HT2C ligands: recent progress. PROGRESS IN MEDICINAL CHEMISTRY 2008; 46:281-390. [PMID: 18381128 DOI: 10.1016/s0079-6468(07)00006-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Nathaniel J T Monck
- Vernalis (R&D) Ltd., 613 Reading Road, Winnersh, Wokingham, Berkshire, RG41 5UA, UK
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Corregiari FM, Gattaz WF, Bernik M. Acute hormonal changes after IV citalopram and treatment response in OCD. Psychopharmacology (Berl) 2007; 193:487-94. [PMID: 17492272 DOI: 10.1007/s00213-007-0793-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2006] [Accepted: 04/03/2007] [Indexed: 10/23/2022]
Abstract
RATIONALE Serotonergic pharmacological challenges have failed to produce consensual results in patients with obsessive-compulsive disorder (OCD), suggesting a heterogeneous 5-hydroxytryptamine (5-HT) activity in this disorder. OBJECTIVES The aim of this study was to compare the neuroendocrine response to a serotonergic challenge in OCD patient responders (RP) and nonresponders (NR) to serotonin reuptake inhibitors treatment and healthy volunteers. MATERIALS AND METHODS Thirty OCD treatment NR, 30 RP, and 30 controls (CN) matched for sex and age were included. Each subject received 20 mg of intravenous citalopram. Prolactin, cortisol, and growth hormone plasma concentration were measured at times-20, 0, 20, 40, 60, 80, 100, 120, 140, and 160 min after the onset of citalopram infusion. RESULTS Citalopram did not induce anxiety or OCD symptoms in patients. Citalopram was associated with stronger prolactin response in the CN group (maximal percentage variation [max%Delta] = 65.76 +/- 105.1) than in NR (max%Delta = 17.41 +/- 31.06) and RP groups (max%Delta = 15.87 +/- 31.71; p = 0.032; Friedman chi (2) = 6.87; df = 2). On the other hand, cortisol response did not differ between CN and RP groups and was blunted in the NR group (NR max%Delta = 20.98 +/- 58.14 vs RP max%Delta = 47.69 +/- 66.94; CN max%Delta = 63.58 +/- 88.4; p = 0.015; Friedman chi (2) = 8.60; df = 2). CONCLUSIONS Compared to CN, both treatment RP and NR patients showed blunted prolactin response to citalopram, but only NR patients showed an attenuated cortisol response, suggesting a more disrupted central serotonergic transmission in this group.
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Affiliation(s)
- Fábio M Corregiari
- Ambulatório de Ansiedade, Instituto de Psiquiatria do Hospital das Clínicas da Faculdade de Medicina, Universidade de São Paulo, Brasil.
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Somerville EM, Horwood JM, Lee MD, Kennett GA, Clifton PG. 5-HT(2C) receptor activation inhibits appetitive and consummatory components of feeding and increases brain c-fos immunoreactivity in mice. Eur J Neurosci 2007; 25:3115-24. [PMID: 17561825 DOI: 10.1111/j.1460-9568.2007.05567.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
5-Hydroxytryptamine (5-HT)(2C) and 5-HT(1B) receptors are implicated in the inhibitory modulation of feeding behaviour. However, their respective, and possibly different, roles have not been clearly identified because of a lack of selective 5-HT(2C) receptor agonists. Here, using the putative, selective 5-HT(2C) receptor agonist VER23779, we show that its effects on feeding are fully reversed by pretreatment with a selective 5-HT(2C) receptor antagonist, but unaffected by pretreatment with either a 5-HT(1B) or a 5-HT(2A) receptor antagonist. In mice eating a palatable mash, feeding ends earlier, inactivity is increased but the behavioural satiety sequence is preserved. In a second-order schedule of reinforcement with an initial, non-food-reinforced appetitive phase, VER23779 produces a much greater relative reduction in appetitive responding than the 5-HT(1B) receptor agonist CP-94,253. Increased c-fos immunoreactivity patterns following VER23779 also differ from those described for CP-94,253, in particular showing strong activation of the basolateral amygdala. The different behavioural consequences of 5-HT(2C) and 5-HT(1B) receptor activation may relate to the patterns of c-fos immunoreactivity. In particular, the basolateral amygdala may have a role in maintaining response in the appetitive phase of the second-order schedule and also be susceptible to serotonergic modulation through activation of 5-HT(2C) receptors.
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Stiedl O, Misane I, Koch M, Pattij T, Meyer M, Ogren SO. Activation of the brain 5-HT2C receptors causes hypolocomotion without anxiogenic-like cardiovascular adjustments in mice. Neuropharmacology 2007; 52:949-57. [PMID: 17141810 DOI: 10.1016/j.neuropharm.2006.10.012] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2005] [Revised: 09/22/2006] [Accepted: 10/19/2006] [Indexed: 11/18/2022]
Abstract
The present study evaluated whether hypolocomotion elicited by subcutaneous administration of the non-specific 5-HT/preferential 5-HT(2C) receptor agonist mCPP during novelty exposure was due to an enhanced anxiety-like state. The effects of mCPP on exploratory behavior during exposure to a new environment (novelty) were studied in male C57BL/6N mice. Subcutaneous injection of mCPP (1 and 3mg/kg) and the preferential 5-HT(2C) receptor agonist MK212 (0.7 and 1mg/kg) induced hypolocomotion during novelty exposure. The selective 5-HT(2C) receptor antagonist SB242084 (0.3mg/kg) reversed the mCPP-induced hypolocomotion into hyperlocomotion. In contrast, MK212 induced hypolocomotion that was blocked by SB242084, indicating a specific 5-HT(2C) receptor involvement. When injected intracerebroventricularly, mCPP (30microg) elicited hypolocomotion, whereas the same dose mildly increased locomotion when injected into the dorsal hippocampus. Since anxiety affects autonomic functions, effects of mCPP on cardiovascular function were studied by radio-telemetry in the home cage of unrestrained mice. Subcutaneous injection of mCPP (3mg/kg) had no significant effect on heart rate and mean arterial blood pressure. In summary, in view of lack of autonomic effects, and the lack of hypoactivity upon forebrain stimulation, the hypolocomotion induced by systemic mCPP cannot be explained by an enhanced anxiety-like state.
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Affiliation(s)
- Oliver Stiedl
- Center for Neurogenomics and Cognitive Research (CNCR) and Institute of Neurosciences (INW), Vrije Universiteit Amsterdam, The Netherlands.
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Fletcher PJ, Sinyard J, Higgins GA. The effects of the 5-HT(2C) receptor antagonist SB242084 on locomotor activity induced by selective, or mixed, indirect serotonergic and dopaminergic agonists. Psychopharmacology (Berl) 2006; 187:515-25. [PMID: 16832658 DOI: 10.1007/s00213-006-0453-9] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2006] [Accepted: 05/20/2006] [Indexed: 11/26/2022]
Abstract
RATIONALE The 5-HT(2C) receptor modulates mesolimbic dopamine (DA) function and the expression of DA-dependent behaviors, including stimulant-induced hyperactivity. The 5-HT(2C) receptor may also be involved in drug-induced locomotion that is 5-HT-dependent. OBJECTIVES This study investigated the effects of the 5-HT(2C) receptor antagonist 6-chloro-5-methyl-1-[[2-[(2-methyl-3-pyridyl)oxy]-5-pyridyl]carbamoyl]-indoline (SB242084) on hyperlocomotion induced by psychomotor stimulants with selective, or mixed, actions on serotonergic and/or dopaminergic systems. MATERIALS AND METHODS Male Sprague-Dawley rats were treated in the presence or absence of SB242084 with releasers/reuptake inhibitors of DA (amphetamine and methylphenidate), 5-HT (fenfluramine and citalopram), or both 5-HT and DA (MDMA and cocaine). In addition, the effects of SB242084 combined with nicotine, morphine, or the 5-HT(1A/1B) receptor agonist RU24969 were examined. Locomotor activity was recorded for 2 h. RESULTS SB242084 potentiated hyperactivity induced by MDMA (2.5-5 mg/kg), amphetamine (0.5 mg/kg), fenfluramine (5 mg/kg), cocaine (10 mg/kg), and methylphenidate (5 mg/kg). SB242084 modestly potentiated nicotine-induced (0.2-0.4 mg/kg) and morphine-induced (2.5 mg/kg) hyperactivity. SB242084 failed to influence hyperactivity induced by RU24969 (0.5-1 mg/kg) or citalopram (10-20mg/kg). CONCLUSION SB242084 potentiated the locomotor stimulant effects of both indirect DA and 5-HT agonists. This potentiation may reflect two distinct mechanisms. The first involves direct enhancement of DA activity as shown by potentiation of the effects of amphetamine and methylphenidate. The second mechanism reflects an unmasking of stimulatory 5-HT receptors activated by 5-HT releasers (possibly 5-HT(1B/2A)) through blockade of inhibitory 5-HT(2C) receptors. The failure of SB242084 to potentiate the effect of citalopram might reflect differences between changes in synaptic levels of 5-HT produced by release compared to reuptake inhibition.
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Affiliation(s)
- Paul J Fletcher
- Section of Biopsychology, Centre for Addiction and Mental Health, Toronto, ON, Canada.
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Dalton GL, Lee MD, Kennett GA, Dourish CT, Clifton PG. Serotonin 1B and 2C receptor interactions in the modulation of feeding behaviour in the mouse. Psychopharmacology (Berl) 2006; 185:45-57. [PMID: 16470405 DOI: 10.1007/s00213-005-0212-3] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2005] [Accepted: 09/19/2005] [Indexed: 10/25/2022]
Abstract
RATIONALE To examine the functional relationship between 5-HT1B receptors (5-HT1B-R) and 5-HT2C receptors (5-HT2C-R) in the control of food intake. OBJECTIVES To compare the hypophagic effect of the 5-HT(2C/1B)-R agonist m-chlorophenylpiperazine (mCPP), with that of the selective 5-HT1B-R agonist CP-94,253 in both wildtype (WT) and 5-HT2C knockout (KO) mice. METHODS The hypophagic effects of mCPP (1, 3 and 5.6 mg/kg) and CP-94,253 (5, 10 and 20 mg/kg) were assessed in WT and 5-HT2C KO mice using the behavioural satiety sequence paradigm. The effects of pre-treatment with the selective 5-HT2C-R antagonist SB 242,084 (0.5 and 1.5 mg/kg) were assessed in two groups of WT mice, with each group given only mCPP or CP-94,253. RESULTS The 5-HT(2C/1B) receptor agonist mCPP and the selective 5-HT1B receptor agonist CP-94,253 both suppressed food intake in WT mice. 5-HT2C KO mice were insensitive to the hypophagic effects of mCPP but were more sensitive to CP-94,253-induced hypophagia than WT controls. mCPP induced a significant increase in post-prandial activity in 5-HT2C KO mice, but this effect was absent in 5-HT2C KO mice who were given CP-94,253. Data from WT mice, who were pre-treated with the 5-HT2C receptor antagonist SB 242,084 and then challenged with either mCPP or CP-94,253, were similar to those obtained from 5-HT2C KO mice. CONCLUSIONS 5-HT2C-R and 5-HT1B-R activation are each sufficient to induce a hypophagic response. However, concurrent 5-HT2C-R inactivation can potentiate the hypophagic response to 5-HT1B-R activation, consistent with an inhibitory role for the 5-HT2C-R in behaviour mediated by the activation of other 5-HT receptors. These results also confirm that 5-HT1B-R activation alone cannot account for the hyperactive response of 5-HT2C KO mice to mCPP.
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Affiliation(s)
- G L Dalton
- Department of Psychology, Sussex University, Brighton, BN1 9QG, UK
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