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Liu H, He Y, Liu H, Brouwers B, Yin N, Lawler K, Keogh JM, Henning E, Lee DK, Yu M, Tu L, Zhang N, Conde KM, Han J, Yan Z, Scarcelli NA, Liao L, Xu J, Tong Q, Zheng H, Sun Z, Yang Y, Wang C, He Y, Farooqi IS, Xu Y. Neural circuits expressing the serotonin 2C receptor regulate memory in mice and humans. SCIENCE ADVANCES 2024; 10:eadl2675. [PMID: 38941473 PMCID: PMC11212768 DOI: 10.1126/sciadv.adl2675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Accepted: 05/22/2024] [Indexed: 06/30/2024]
Abstract
Declined memory is a hallmark of Alzheimer's disease (AD). Experiments in rodents and human postmortem studies suggest that serotonin (5-hydroxytryptamine, 5-HT) plays a role in memory, but the underlying mechanisms are unknown. Here, we investigate the role of 5-HT 2C receptor (5-HT2CR) in regulating memory. Transgenic mice expressing a humanized HTR2C mutation exhibit impaired plasticity of hippocampal ventral CA1 (vCA1) neurons and reduced memory. Further, 5-HT neurons project to and synapse onto vCA1 neurons. Disruption of 5-HT synthesis in vCA1-projecting neurons or deletion of 5-HT2CRs in the vCA1 impairs neural plasticity and memory. We show that a selective 5-HT2CR agonist, lorcaserin, improves synaptic plasticity and memory in an AD mouse model. Cumulatively, we demonstrate that hippocampal 5-HT2CR signaling regulates memory, which may inform the use of 5-HT2CR agonists in the treatment of dementia.
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Affiliation(s)
- Hesong Liu
- USDA/ARS, Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Yang He
- USDA/ARS, Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, TX 77030, USA
- Department of Pediatrics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Hailan Liu
- USDA/ARS, Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Bas Brouwers
- University of Cambridge Metabolic Research Laboratories and NIHR Cambridge Biomedical Research Centre, Wellcome-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK
| | - Na Yin
- USDA/ARS, Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Katherine Lawler
- University of Cambridge Metabolic Research Laboratories and NIHR Cambridge Biomedical Research Centre, Wellcome-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK
| | - Julia M. Keogh
- University of Cambridge Metabolic Research Laboratories and NIHR Cambridge Biomedical Research Centre, Wellcome-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK
| | - Elana Henning
- University of Cambridge Metabolic Research Laboratories and NIHR Cambridge Biomedical Research Centre, Wellcome-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK
| | - Dong-Kee Lee
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Meng Yu
- USDA/ARS, Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Longlong Tu
- USDA/ARS, Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Nan Zhang
- USDA/ARS, Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Kristine M. Conde
- USDA/ARS, Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Junying Han
- USDA/ARS, Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Zili Yan
- USDA/ARS, Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Nikolas A. Scarcelli
- USDA/ARS, Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Lan Liao
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jianming Xu
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Qingchun Tong
- Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Hui Zheng
- Huffington Center on Aging, Baylor College of Medicine, Houston, TX 77030, USA
| | - Zheng Sun
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Medicine, Baylor College of Medicine, Houston, TX 77030, USA
| | - Yongjie Yang
- USDA/ARS, Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Chunmei Wang
- USDA/ARS, Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Yanlin He
- Pennington Biomedical Research Center, Brain Glycemic and Metabolism Control Department, Louisiana State University, Baton Rouge, LA 70808, USA
| | - I. Sadaf Farooqi
- University of Cambridge Metabolic Research Laboratories and NIHR Cambridge Biomedical Research Centre, Wellcome-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK
| | - Yong Xu
- USDA/ARS, Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Medicine, Baylor College of Medicine, Houston, TX 77030, USA
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Dell'isola GB, Verrotti A, Sciaccaluga M, Roberti R, Parnetti L, Russo E, Costa C. Evaluating bexicaserin for the treatment of developmental epileptic encephalopathies. Expert Opin Pharmacother 2024; 25:1121-1130. [PMID: 38916481 DOI: 10.1080/14656566.2024.2373350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2024] [Accepted: 06/24/2024] [Indexed: 06/26/2024]
Abstract
INTRODUCTION Developmental epileptic encephalopathies (DEEs) pose significant challenges due to their refractory nature and limited treatment options. Despite advancements in genetic understanding, effective therapies targeting underlying pathophysiology are lacking. Serotoninergic dysfunction has been implicated in epilepsy, sparking interest in serotonin as a therapeutic target. AREA COVERED This article explores the potential of bexicaserin, a selective 5-HT2C receptor agonist, as an adjunctive antiseizure medication in DEEs. Bexicaserin is thought to modulate GABAergic neurotransmission, suppressing central hyperexcitability. Preclinical studies demonstrate its efficacy across various seizure models. Clinical trials, including the Pacific Study, reveal promising results in reducing motor seizures. However, challenges such as adverse effects and treatment discontinuation underscore the need for further investigation. EXPERT OPINION The efficacy of 5-HT2C serotoninergic agonists, validated in preclinical and clinical studies, highlights serotonin's role in DEEs. Bexicaserin offers new therapeutic possibilities, potentially synergizing with existing antiseizure medications. Polypharmacotherapy, targeting distinct pathways, may enhance therapeutic outcomes. Monitoring pharmacological interactions and addressing central nervous system comorbidities are crucial for optimizing treatment strategies. Further research is needed to elucidate bexicaserin's mechanisms and potential antiepileptogenic effects.
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Affiliation(s)
| | | | - Miriam Sciaccaluga
- Section of Neurology, Laboratory of Experimental Neurology, Department of Medicine and Surgery, University of Perugia, Perugia, Italy
- Mauro Baschirotto Rare Disease Foundation BIRD Onlus, Longare, VI, Italy
| | - Roberta Roberti
- Science of Health Department, University Magna Grecia of Catanzaro, Catanzaro, Italy
| | - Lucilla Parnetti
- Section of Neurology, Laboratory of Experimental Neurology, Department of Medicine and Surgery, University of Perugia, Perugia, Italy
| | - Emilio Russo
- Science of Health Department, University Magna Grecia of Catanzaro, Catanzaro, Italy
| | - Cinzia Costa
- Section of Neurology, Laboratory of Experimental Neurology, Department of Medicine and Surgery, University of Perugia, Perugia, Italy
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Constitutive 5-HT2C receptor knock-out facilitates fear extinction through altered activity of a dorsal raphe-bed nucleus of the stria terminalis pathway. Transl Psychiatry 2022; 12:487. [PMID: 36402746 PMCID: PMC9675804 DOI: 10.1038/s41398-022-02252-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 10/24/2022] [Accepted: 11/07/2022] [Indexed: 11/21/2022] Open
Abstract
Serotonin 2C receptors (5-HT2CRs) are widely distributed throughout the brain and are strongly implicated in the pathophysiology of anxiety disorders such as post-traumatic stress disorder (PTSD). Although in recent years, a considerable amount of evidence supports 5-HT2CRs facilitating effect on anxiety behavior, the involvement in learned fear responses and fear extinction is rather unexplored. Here, we used a 5-HT2CR knock-out mouse line (2CKO) to gain new insights into the involvement of 5-HT2CRs in the neuronal fear circuitry. Using a cued fear conditioning paradigm, our results revealed that global loss of 5-HT2CRs exclusively accelerates fear extinction, without affecting fear acquisition and fear expression. To investigate the neuronal substrates underlying the extinction enhancing effect, we mapped the immediate-early gene product cFos, a marker for neuronal activity, in the dorsal raphe nucleus (DRN), amygdala and bed nucleus of the stria terminalis (BNST). Surprisingly, besides extinction-associated changes, our results revealed alterations in neuronal activity even under basal home cage conditions in specific subregions of the DRN and the BNST in 2CKO mice. Neuronal activity in the dorsal BNST was shifted in an extinction-supporting direction due to 5-HT2CR knock-out. Finally, the assessment of DRN-BNST connectivity using antero- and retrograde tracing techniques uncovered a discrete serotonergic pathway projecting from the most caudal subregion of the DRN (DRC) to the anterodorsal portion of the BNST (BNSTad). This serotonergic DRC-BNSTad pathway showed increased neuronal activity in 2CKO mice. Thus, our results provide new insights for the fear extinction network by revealing a specific serotonergic DRC-BNSTad pathway underlying a 5-HT2CR-sensitive mechanism with high significance in the treatment of PTSD.
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Babushkina N, Manahan-Vaughan D. Frequency-dependency of the involvement of dopamine D1/D5 and beta-adrenergic receptors in hippocampal LTD triggered by locus coeruleus stimulation. Hippocampus 2022; 32:449-465. [PMID: 35478421 DOI: 10.1002/hipo.23419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 04/01/2022] [Accepted: 04/07/2022] [Indexed: 11/06/2022]
Abstract
Patterned stimulation of the locus coeruleus (LC, 100 Hz), in conjunction with test-pulse stimulation of hippocampal afferents, results in input-specific long-term depression (LTD) of synaptic plasticity in the hippocampus. Effects are long-lasting and have been described in Schaffer-collateral-CA1 and perforant path-dentate gyrus synapses in behaving rats. To what extent LC-mediated hippocampal LTD (LC-LTD) is frequency-dependent is unclear. Here, we report that LC-LTD can be triggered by LC stimulation with 2 and 5 Hz akin to tonic activity, 10 Hz equivalent to phasic activity, and 100 Hz akin to high-phasic activity in the dentate gyrus (DG) of freely behaving rats. LC-LTD at both 2 and 100 Hz can be significantly prevented by an NMDA receptor antagonist. The LC releases both noradrenaline (NA) and dopamine (DA) from its hippocampal terminals and may also trigger hippocampal DA release by activating the ventral tegmental area (VTA). Unclear is whether both neurotransmitters contribute equally to hippocampal LTD triggered by LC stimulation (LC-LTD). Both DA D1/D5 receptors (D1/D5R) and beta-adrenergic receptors (β-AR) are critically required for hippocampal LTD that is induced by patterned stimulation of hippocampal afferents, or is facilitated by spatial learning. We, therefore, explored to what extent these receptor subtypes mediate frequency-dependent hippocampal LC-LTD. LC-LTD elicited by 2, 5, and 10 Hz stimulation was unaffected by antagonism of β-AR with propranolol, whereas LC-LTD induced by these frequencies was prevented by D1/D5R-antagonism using SCH23390. By contrast, LC-LTD evoked at 100 Hz was prevented by β-AR-antagonism and only mildly affected by D1/D5R-antagonism. Taken together, these findings support that LC-LTD can be triggered by LC activity at a wide range of frequencies. Furthermore, the contribution of D1/D5R and β-AR to hippocampal LTD that is triggered by LC activity is frequency-dependent and suggests that D1/D5R may be involved in LC-mediated hippocampal tonus.
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Affiliation(s)
- Natalia Babushkina
- Medical Faculty, Department of Neurophysiology, Ruhr University Bochum, Bochum, Germany.,International Graduate School of Neuroscience, Ruhr University Bochum, Bochum, Germany
| | - Denise Manahan-Vaughan
- Medical Faculty, Department of Neurophysiology, Ruhr University Bochum, Bochum, Germany.,International Graduate School of Neuroscience, Ruhr University Bochum, Bochum, Germany
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Human loss-of-function variants in the serotonin 2C receptor associated with obesity and maladaptive behavior. Nat Med 2022; 28:2537-2546. [PMID: 36536256 PMCID: PMC9800280 DOI: 10.1038/s41591-022-02106-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 10/25/2022] [Indexed: 12/24/2022]
Abstract
Serotonin reuptake inhibitors and receptor agonists are used to treat obesity, anxiety and depression. Here we studied the role of the serotonin 2C receptor (5-HT2CR) in weight regulation and behavior. Using exome sequencing of 2,548 people with severe obesity and 1,117 control individuals without obesity, we identified 13 rare variants in the gene encoding 5-HT2CR (HTR2C) in 19 unrelated people (3 males and 16 females). Eleven variants caused a loss of function in HEK293 cells. All people who carried variants had hyperphagia and some degree of maladaptive behavior. Knock-in male mice harboring a human loss-of-function HTR2C variant developed obesity and reduced social exploratory behavior; female mice heterozygous for the same variant showed similar deficits with reduced severity. Using the 5-HT2CR agonist lorcaserin, we found that depolarization of appetite-suppressing proopiomelanocortin neurons was impaired in knock-in mice. In conclusion, we demonstrate that 5-HT2CR is involved in the regulation of human appetite, weight and behavior. Our findings suggest that melanocortin receptor agonists might be effective in treating severe obesity in individuals carrying HTR2C variants. We suggest that HTR2C should be included in diagnostic gene panels for severe childhood-onset obesity.
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Mitra S, Bult-Ito A. Bidirectional Behavioral Selection in Mice: A Novel Pre-clinical Approach to Examining Compulsivity. Front Psychiatry 2021; 12:716619. [PMID: 34566718 PMCID: PMC8458042 DOI: 10.3389/fpsyt.2021.716619] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 08/16/2021] [Indexed: 11/17/2022] Open
Abstract
Obsessive-compulsive disorder (OCD) and related disorders (OCRD) is one of the most prevalent neuropsychiatric disorders with no definitive etiology. The pathophysiological attributes of OCD are driven by a multitude of factors that involve polygenic mechanisms, gender, neurochemistry, physiological status, environmental exposures and complex interactions among these factors. Such complex intertwining of contributing factors imparts clinical heterogeneity to the disorder making it challenging for therapeutic intervention. Mouse strains selected for excessive levels of nest- building behavior exhibit a spontaneous, stable and predictable compulsive-like behavioral phenotype. These compulsive-like mice exhibit heterogeneity in expression of compulsive-like and other adjunct behaviors that might serve as a valuable animal equivalent for examining the interactions of genetics, sex and environmental factors in influencing the pathophysiology of OCD. The current review summarizes the existing findings on the compulsive-like mice that bolster their face, construct and predictive validity for studying various dimensions of compulsive and associated behaviors often reported in clinical OCD and OCRD.
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Affiliation(s)
- Swarup Mitra
- Department of Pharmacology and Toxicology, State University of New York at Buffalo, Buffalo, NY, United States
| | - Abel Bult-Ito
- Department of Biology and Wildlife, University of Alaska Fairbanks, Fairbanks, AK, United States
- OCRD Biomed LLC, Fairbanks, AK, United States
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Massey CA, Thompson SJ, Ostrom RW, Drabek J, Sveinsson OA, Tomson T, Haas EA, Mena OJ, Goldman AM, Noebels JL. X-linked serotonin 2C receptor is associated with a non-canonical pathway for sudden unexpected death in epilepsy. Brain Commun 2021; 3:fcab149. [PMID: 34396109 PMCID: PMC8361391 DOI: 10.1093/braincomms/fcab149] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 04/14/2021] [Accepted: 05/07/2021] [Indexed: 11/13/2022] Open
Abstract
Sudden Unexpected Death in Epilepsy is a leading cause of epilepsy-related mortality, and the analysis of mouse Sudden Unexpected Death in Epilepsy models is steadily revealing a spectrum of inherited risk phenotypes based on distinct genetic mechanisms. Serotonin (5-HT) signalling enhances post-ictal cardiorespiratory drive and, when elevated in the brain, reduces death following evoked audiogenic brainstem seizures in inbred mouse models. However, no gene in this pathway has yet been linked to a spontaneous epilepsy phenotype, the defining criterion of Sudden Unexpected Death in Epilepsy. Most monogenic models of Sudden Unexpected Death in Epilepsy invoke a failure of inhibitory synaptic drive as a critical pathogenic step. Accordingly, the G protein-coupled, membrane serotonin receptor 5-HT2C inhibits forebrain and brainstem networks by exciting GABAergic interneurons, and deletion of this gene lowers the threshold for lethal evoked audiogenic seizures. Here, we characterize epileptogenesis throughout the lifespan of mice lacking X-linked, 5-HT2C receptors (loxTB Htr2c). We find that loss of Htr2c generates a complex, adult-onset spontaneous epileptic phenotype with a novel progressive hyperexcitability pattern of absences, non-convulsive, and convulsive behavioural seizures culminating in late onset sudden mortality predominantly in male mice. RNAscope localized Htr2c mRNA in subsets of Gad2+ GABAergic neurons in forebrain and brainstem regions. To evaluate the contribution of 5-HT2C receptor-mediated inhibitory drive, we selectively spared their deletion in GAD2+ GABAergic neurons of pan-deleted loxTB Htr2c mice, yet unexpectedly found no amelioration of survival or epileptic phenotype, indicating that expression of 5-HT2C receptors in GAD2+ inhibitory neurons was not sufficient to prevent hyperexcitability and lethal seizures. Analysis of human Sudden Unexpected Death in Epilepsy and epilepsy genetic databases identified an enrichment of HTR2C non-synonymous variants in Sudden Unexpected Death in Epilepsy cases. Interestingly, while early lethality is not reflected in the mouse model, we also identified variants mainly among male Sudden Infant Death Syndrome patients. Our findings validate HTR2C as a novel, sex-linked candidate gene modifying Sudden Unexpected Death in Epilepsy risk, and demonstrate that the complex epilepsy phenotype does not arise solely from 5-HT2C-mediated synaptic disinhibition. These results strengthen the evidence for the serotonin hypothesis of Sudden Unexpected Death in Epilepsy risk in humans, and advance current efforts to develop gene-guided interventions to mitigate premature mortality in epilepsy.
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Affiliation(s)
- Cory A Massey
- Developmental Neurogenetics Laboratory, Department of Neurology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Samantha J Thompson
- Developmental Neurogenetics Laboratory, Department of Neurology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Ryan W Ostrom
- Developmental Neurogenetics Laboratory, Department of Neurology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Janice Drabek
- Developmental Neurogenetics Laboratory, Department of Neurology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Olafur A Sveinsson
- Department of Neurology, National University Hospital of Iceland, 101 Reykjavik, Iceland
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm 171 76, Sweden
| | - Torbjörn Tomson
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm 171 76, Sweden
| | - Elisabeth A Haas
- Department of Pathology, Rady Children’s Hospital-San Diego, San Diego, CA 92123, USA
| | - Othon J Mena
- Medical Examiner Office, Ventura County Health Care Agency, Ventura, CA 93003, USA
| | - Alica M Goldman
- Developmental Neurogenetics Laboratory, Department of Neurology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jeffrey L Noebels
- Developmental Neurogenetics Laboratory, Department of Neurology, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Human and Molecular Genetics, Baylor College of Medicine, Houston, TX 77030, USA
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Bombardi C, Delicata F, Tagliavia C, Grandis A, Pierucci M, Marino Gammazza A, Casarrubea M, De Deurwaerdère P, Di Giovanni G. Lateral Habenula 5-HT 2C Receptor Function Is Altered by Acute and Chronic Nicotine Exposures. Int J Mol Sci 2021; 22:ijms22094775. [PMID: 33946328 PMCID: PMC8124296 DOI: 10.3390/ijms22094775] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 04/25/2021] [Accepted: 04/27/2021] [Indexed: 12/11/2022] Open
Abstract
Serotonin (5-HT) is important in some nicotine actions in the CNS. Among all the 5-HT receptors (5-HTRs), the 5-HT2CR has emerged as a promising drug target for smoking cessation. The 5-HT2CRs within the lateral habenula (LHb) may be crucial for nicotine addiction. Here we showed that after acute nicotine tartrate (2 mg/kg, i.p.) exposure, the 5-HT2CR agonist Ro 60-0175 (5–640 µg/kg, i.v.) increased the electrical activity of 42% of the LHb recorded neurons in vivo in rats. Conversely, after chronic nicotine treatment (6 mg/kg/day, i.p., for 14 days), Ro 60-0175 was incapable of affecting the LHb neuronal discharge. Moreover, acute nicotine exposure increased the 5-HT2CR-immunoreactive (IR) area while decreasing the number of 5-HT2CR-IR neurons in the LHb. On the other hand, chronic nicotine increased both the 5-HT2CR-IR area and 5-HT2CR-IR LHb neurons in the LHb. Western blot analysis confirmed these findings and further revealed an increase of 5-HT2CR expression in the medial prefrontal cortex after chronic nicotine exposure not detected by the immunohistochemistry. Altogether, these data show that acute and chronic nicotine exposure differentially affect the central 5-HT2CR function mainly in the LHb and this may be relevant in nicotine addiction and its treatment.
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Affiliation(s)
- Cristiano Bombardi
- Department of Veterinary Medical Sciences, University of Bologna, Via Tolara di Sopra, 50, 40064 Ozzano dell’Emilia, Italy; (C.B.); (C.T.); (A.G.)
| | - Francis Delicata
- Laboratory of Neurophysiology, Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, MSD2080 Msida, Malta; (F.D.); (M.P.)
| | - Claudio Tagliavia
- Department of Veterinary Medical Sciences, University of Bologna, Via Tolara di Sopra, 50, 40064 Ozzano dell’Emilia, Italy; (C.B.); (C.T.); (A.G.)
| | - Annamaria Grandis
- Department of Veterinary Medical Sciences, University of Bologna, Via Tolara di Sopra, 50, 40064 Ozzano dell’Emilia, Italy; (C.B.); (C.T.); (A.G.)
| | - Massimo Pierucci
- Laboratory of Neurophysiology, Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, MSD2080 Msida, Malta; (F.D.); (M.P.)
| | - Antonella Marino Gammazza
- Section of Human Anatomy, Department of Biomedicine, Neuroscience and Advanced Diagnostics (BiND), University of Palermo, 90127 Palermo, Italy;
| | - Maurizio Casarrubea
- Laboratory of Behavioral Physiology, Human Physiology Section “Giuseppe Pagano”, Department of Biomedicine, Neuroscience and Advanced Diagnostics (BiND), University of Palermo, 90127 Palermo, Italy;
| | - Philippe De Deurwaerdère
- Unité Mixte de Recherche 5287, Centre National de la Recherche Scientifique, 146 rue Léo Saignat, B.P.281, CEDEX, F-33000 Bordeaux, France;
| | - Giuseppe Di Giovanni
- Laboratory of Neurophysiology, Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, MSD2080 Msida, Malta; (F.D.); (M.P.)
- School of Biosciences, Cardiff University, Cardiff CF10 3AX, UK
- Correspondence: or ; Tel.: +356-23402776
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Bombardi C, Grandis A, Pivac N, Sagud M, Lucas G, Chagraoui A, Lemaire-Mayo V, De Deurwaerdère P, Di Giovanni G. Serotonin modulation of hippocampal functions: From anatomy to neurotherapeutics. PROGRESS IN BRAIN RESEARCH 2021; 261:83-158. [PMID: 33785139 DOI: 10.1016/bs.pbr.2021.01.031] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The hippocampal region receives a dense serotoninergic innervation originating from both medial and dorsal raphe nuclei. This innervation regulates hippocampal activity through the activation of distinct receptor families that are expressed in excitatory and inhibitory neurons, terminals of several afferent neurotransmitter systems, and glial cells. Preclinical and clinical studies indicate that hippocampal dysfunctions are involved in learning and memory deficits, dementia, Alzheimer's disease, epilepsy and mood disorders such as anxiety, depression and post-traumatic syndrome disorder, whereas the hippocampus participates also in the therapeutic mechanisms of numerous medicines. Not surprisingly, several drugs acting via 5-HT mechanisms are efficacious to some extent in some diseases and the link between 5-HT and the hippocampus although clear remains difficult to untangle. For this reason, we review reported data concerning the distribution and the functional roles of the 5-HT receptors in the hippocampal region in health and disease. The impact of the 5-HT systems on the hippocampal function is such that the research of new 5-HT mechanisms and drugs is still very active. It concerns notably drugs acting at the 5-HT1A,2A,2C,4,6 receptor subtypes, in addition to the already existing drugs including the selective serotonin reuptake inhibitors.
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Affiliation(s)
- Cristiano Bombardi
- Department of Veterinary Medical Sciences, University of Bologna, Bologna, Italy.
| | - Annamaria Grandis
- Department of Veterinary Medical Sciences, University of Bologna, Bologna, Italy
| | - Nela Pivac
- Division of Molecular Medicine, Rudier Boskovic Institute, Zagreb, Croatia
| | - Marina Sagud
- Clinical Hospital Center Zagreb and School of Medicine University of Zagreb, Zagreb, Croatia
| | - Guillaume Lucas
- Neurocentre Magendie, INSERM 1215, Université de Bordeaux, Bordeaux, France
| | - Abdeslam Chagraoui
- Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, Institute for Research and Innovation in Biomedicine of Normandy (IRIB), Normandie University, UNIROUEN, INSERM U1239, Rouen, France; Department of Medical Biochemistry, Rouen University Hospital, Rouen, France
| | - Valérie Lemaire-Mayo
- Centre National de la Recherche Scientifique, Institut des Neurosciences Intégratives et Cognitives d'Aquitaine, UMR 5287, Bordeaux, France
| | - Philippe De Deurwaerdère
- Centre National de la Recherche Scientifique, Institut des Neurosciences Intégratives et Cognitives d'Aquitaine, UMR 5287, Bordeaux, France
| | - Giuseppe Di Giovanni
- Laboratory of Neurophysiology, Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Msida, Malta; Neuroscience Division, School of Biosciences, Cardiff University, Cardiff, United Kingdom
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Hao R, Qi Y, Hou DN, Ji YY, Zheng CY, Li CY, Yung WH, Lu B, Huang Y. BDNF val66met Polymorphism Impairs Hippocampal Long-Term Depression by Down-Regulation of 5-HT3 Receptors. Front Cell Neurosci 2017; 11:306. [PMID: 29075179 PMCID: PMC5643500 DOI: 10.3389/fncel.2017.00306] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Accepted: 09/13/2017] [Indexed: 12/17/2022] Open
Abstract
Brain-derived neurotrophic factor (BDNF) is a key regulator of neuronal plasticity and cognitive functions. BDNF val66met polymorphism, a human single-nucleotide polymorphism (SNP) in the pro-domain of BDNF gene, is associated with deficits in activity-dependent BDNF secretion and hippocampus-dependent memory. However, the underlying mechanism remains unclear. Here we show that in the BDNFMet/Met mouse line mimicking the human SNP, BDNF expression in the hippocampus was decreased. There was a reduction in the total number of cells in hippocampal CA1 region, while hippocampal expression of mRNAs for NR2a, 2b, GluR1, 2 and GABAARβ3 subunits were up-regulated. Although basal glutamatergic neurotransmission was unaltered, hippocampal long-term depression (LTD) induced by low-frequency stimulation was impaired, which was partially rescued by exogenous application of BDNF. Interestingly, 5-HT3a receptors were down-regulated in the hippocampus of BDNFMet/Met mice, whereas 5-HT2c receptors were up-regulated. Moreover, impaired LTD in BDNFMet/Met mice was reversed by 5-HT3aR agonist. Thus, these observations indicate that BDNF val66met polymorphism changes hippocampal synaptic plasticity via down-regulation of 5-HT3a receptors, which may underlie cognition dysfunction of Met allele carriers.
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Affiliation(s)
- Rui Hao
- Laboratory of Neuronal Circuit & Neuroplasticity, Department of Neurology, Tongji Hospital, Shanghai, China.,Department of Physiology and Pharmacology, Tongji University School of Medicine, Shanghai, China.,Department of Physiology and Pathophysiology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Yu Qi
- Laboratory of Neuronal Circuit & Neuroplasticity, Department of Neurology, Tongji Hospital, Shanghai, China.,Department of Physiology and Pharmacology, Tongji University School of Medicine, Shanghai, China.,Department of Physiology and Pathophysiology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Dong-Ni Hou
- Department of Physiology and Pathophysiology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Yuan-Yuan Ji
- Neurodegeneration Discovery Performance Unit, GlaxoSmithKline (China) R&D, Shanghai, China
| | - Chun-Yan Zheng
- Neurodegeneration Discovery Performance Unit, GlaxoSmithKline (China) R&D, Shanghai, China
| | - Chu-Yu Li
- Department of Physiology and Pathophysiology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Wing-Ho Yung
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Bai Lu
- School of Pharmaceutical Sciences, Tsinghua University, Beijing, China
| | - Ying Huang
- Laboratory of Neuronal Circuit & Neuroplasticity, Department of Neurology, Tongji Hospital, Shanghai, China.,Department of Physiology and Pharmacology, Tongji University School of Medicine, Shanghai, China.,Department of Physiology and Pathophysiology, Shanghai Medical College, Fudan University, Shanghai, China
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11
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Kraus C, Castrén E, Kasper S, Lanzenberger R. Serotonin and neuroplasticity - Links between molecular, functional and structural pathophysiology in depression. Neurosci Biobehav Rev 2017; 77:317-326. [PMID: 28342763 DOI: 10.1016/j.neubiorev.2017.03.007] [Citation(s) in RCA: 254] [Impact Index Per Article: 36.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2017] [Revised: 02/23/2017] [Accepted: 03/12/2017] [Indexed: 12/26/2022]
Abstract
Serotonin modulates neuroplasticity, especially during early life, and dysfunctions in both systems likewise contribute to pathophysiology of depression. Recent findings demonstrate that serotonin reuptake inhibitors trigger reactivation of juvenile-like neuroplasticity. How these findings translate to clinical antidepressant treatment in major depressive disorder remains unclear. With this review, we link preclinical with clinical work on serotonin and neuroplasticity to bring two pathophysiologic models in clinical depression closer together. Dysfunctional developmental plasticity impacts on later-life cognitive and emotional functions, changes of synaptic serotonin levels and receptor levels are coupled with altered synaptic plasticity and neurogenesis. Structural magnetic resonance imaging in patients reveals disease-state-specific reductions of gray matter, a marker of neuroplasticity, and reversibility upon selective serotonin reuptake inhibitor treatment. Translational evidence from magnetic resonance imaging in animals support that reduced densities and sizes of neurons and reduced hippocampal volumes in depressive patients could be attributable to changes of serotonergic neuroplasticity. Since ketamine, physical exercise or learning enhance neuroplasticity, combinatory paradigms with selective serotonin reuptake inhibitors could enhance clinical treatment of depression.
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Affiliation(s)
- Christoph Kraus
- NEUROIMAGING LABs (NIL) - PET & MRI & EEG & Chemical Lab Department of Psychiatry and Psychotherapy Medical University of Vienna
| | - Eero Castrén
- Neuroscience Center, University of Helsinki, Helsinki, Finland
| | - Siegfried Kasper
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria(1)
| | - Rupert Lanzenberger
- NEUROIMAGING LABs (NIL) - PET & MRI & EEG & Chemical Lab Department of Psychiatry and Psychotherapy Medical University of Vienna.
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12
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Sanders J, Mayford M. Chronic fluoxetine dissociates contextual from auditory fear memory. Neurosci Lett 2016; 632:152-6. [PMID: 27592057 DOI: 10.1016/j.neulet.2016.08.057] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 08/18/2016] [Accepted: 08/30/2016] [Indexed: 11/30/2022]
Abstract
Fluoxetine is a medication used to treat Major Depressive Disorder and other psychiatric conditions. These experiments studied the effects of chronic fluoxetine treatment on the contextual versus auditory fear memory of mice. We found that chronic fluoxetine treatment of adult mice impaired their contextual fear memory, but spared auditory fear memory. Hippocampal perineuronal nets, which are involved in contextual fear memory plasticity, were unaltered by fluoxetine treatment. These data point to a selective inability to form contextual fear memory as a result of fluoxetine treatment, and they suggest that a blunting of hippocampal-mediated aversive memory may be a therapeutic action for this medication.
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Affiliation(s)
- Jeff Sanders
- Department of Psychiatry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0603, United States.
| | - Mark Mayford
- Department of Psychiatry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0603, United States
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13
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Chagraoui A, Thibaut F, Skiba M, Thuillez C, Bourin M. 5-HT2C receptors in psychiatric disorders: A review. Prog Neuropsychopharmacol Biol Psychiatry 2016; 66:120-135. [PMID: 26739950 DOI: 10.1016/j.pnpbp.2015.12.006] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 12/25/2015] [Accepted: 12/26/2015] [Indexed: 12/26/2022]
Abstract
5-HT2Rs have a different genomic organization from other 5-HT2Rs. 5HT2CR undergoes post-transcriptional pre-mRNA editing generating diversity among RNA transcripts. Selective post-transcriptional editing could be involved in the pathophysiology of psychiatric disorders through impairment in G-protein interactions. Moreover, it may influence the therapeutic response to agents such as atypical antipsychotic drugs. Additionally, 5-HT2CR exhibits alternative splicing. Central serotonergic and dopaminergic systems interact to modulate normal and abnormal behaviors. Thus, 5HT2CR plays a crucial role in psychiatric disorders. 5HT2CR could be a relevant pharmacological target in the treatment of neuropsychiatric disorders. The development of drugs that specifically target 5-HT2C receptors will allow for better understanding of their involvement in the pathophysiology of psychiatric disorders including schizophrenia, anxiety, and depression. Among therapeutic means currently available, most drugs used to treat highly morbid psychiatric diseases interact at least partly with 5-HT2CRs. Pharmacologically, 5HT2CRs, have the ability to generate differentially distinct response signal transduction pathways depending on the type of 5HT2CR agonist. Although this receptor property has been clearly demonstrated, in vitro, the eventual beneficial impact of this property opens new perspectives in the development of agonists that could activate signal transduction pathways leading to better therapeutic efficiency with fewer adverse effects.
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Affiliation(s)
- A Chagraoui
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, Institute for Research and Innovation in Biomedicine, Normandy University, France; Department of Medical Biochemistry, Rouen University Hospital, Rouen, France.
| | - F Thibaut
- Department of Psychiatry, University Hospital Cochin (site Tarnier), University of Paris-Descartes and INSERM U 894 Laboratory of Psychiatry and Neurosciences, Paris, France
| | - M Skiba
- Inserm U982, Laboratory of Neuronal and Neuroendocrine Differentiation and Communication, Institute for Research and Innovation in Biomedicine, Normandy University, France
| | - C Thuillez
- Department of Pharmacology, Rouen University Hospital, Rouen, France; INSERM U1096, Laboratory of New Pharmacological Targets for Endothelial Protection and Heart Failure, Institute for Research and Innovation in Biomedicine, Normandy University, France
| | - M Bourin
- EA 3256 Neurobiology of Anxiety and Depression, Faculté de Médecine, BP 53508, 1 rue Gaston Veil, F44035 Nantes Cedex 01, France
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14
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Abstract
The hippocampus plays an important role in emotional and cognitive processing, and both of these domains are affected in patients with major depressive disorder (MDD). Extensive preclinical research and the notion that modulation of serotonin (5-HT) neurotransmission plays a key role in the therapeutic efficacy of selective serotonin reuptake inhibitors (SSRIs) support the view that 5-HT is important for hippocampal function in normal and disease-like conditions. The hippocampus is densely innervated by serotonergic fibers, and the majority of 5-HT receptor subtypes are expressed there. Furthermore, hippocampal cells often co-express multiple 5-HT receptor subtypes that can have either complementary or opposing effects on cell function, adding to the complexity of 5-HT neurotransmission. Here we review the current knowledge of how 5-HT, through its various receptor subtypes, modulates hippocampal output and the activity of hippocampal pyramidal cells in rodents. In addition, we discuss the relevance of 5-HT modulation for cognitive processing in rodents and possible clinical implications of these results in patients with MDD. Finally, we review the data on how SSRIs and vortioxetine, an antidepressant with multimodal activity, affect hippocampal function, including cognitive processing, from both a preclinical and clinical perspective.
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15
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Alonso P, López-Solà C, Real E, Segalàs C, Menchón JM. Animal models of obsessive-compulsive disorder: utility and limitations. Neuropsychiatr Dis Treat 2015; 11:1939-55. [PMID: 26346234 PMCID: PMC4531004 DOI: 10.2147/ndt.s62785] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Obsessive-compulsive disorder (OCD) is a disabling and common neuropsychiatric condition of poorly known etiology. Many attempts have been made in the last few years to develop animal models of OCD with the aim of clarifying the genetic, neurochemical, and neuroanatomical basis of the disorder, as well as of developing novel pharmacological and neurosurgical treatments that may help to improve the prognosis of the illness. The latter goal is particularly important given that around 40% of patients with OCD do not respond to currently available therapies. This article summarizes strengths and limitations of the leading animal models of OCD including genetic, pharmacologically induced, behavioral manipulation-based, and neurodevelopmental models according to their face, construct, and predictive validity. On the basis of this evaluation, we discuss that currently labeled "animal models of OCD" should be regarded not as models of OCD but, rather, as animal models of different psychopathological processes, such as compulsivity, stereotypy, or perseverance, that are present not only in OCD but also in other psychiatric or neurological disorders. Animal models might constitute a challenging approach to study the neural and genetic mechanism of these phenomena from a trans-diagnostic perspective. Animal models are also of particular interest as tools for developing new therapeutic options for OCD, with the greatest convergence focusing on the glutamatergic system, the role of ovarian and related hormones, and the exploration of new potential targets for deep brain stimulation. Finally, future research on neurocognitive deficits associated with OCD through the use of analogous animal tasks could also provide a genuine opportunity to disentangle the complex etiology of the disorder.
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Affiliation(s)
- Pino Alonso
- OCD Clinical and Research Unit, Department of Psychiatry, Hospital de Bellvitge, Barcelona, Spain ; Bellvitge Biomedical Research Institute-IDIBELL, Barcelona, Spain ; Centro de Investigación en Red de Salud Mental, Carlos III Health Institute, Barcelona, Spain ; Department of Clinical Sciences, Bellvitge Campus, University of Barcelona, Barcelona, Spain
| | - Clara López-Solà
- OCD Clinical and Research Unit, Department of Psychiatry, Hospital de Bellvitge, Barcelona, Spain ; Bellvitge Biomedical Research Institute-IDIBELL, Barcelona, Spain ; Centro de Investigación en Red de Salud Mental, Carlos III Health Institute, Barcelona, Spain
| | - Eva Real
- OCD Clinical and Research Unit, Department of Psychiatry, Hospital de Bellvitge, Barcelona, Spain ; Bellvitge Biomedical Research Institute-IDIBELL, Barcelona, Spain ; Centro de Investigación en Red de Salud Mental, Carlos III Health Institute, Barcelona, Spain
| | - Cinto Segalàs
- OCD Clinical and Research Unit, Department of Psychiatry, Hospital de Bellvitge, Barcelona, Spain ; Bellvitge Biomedical Research Institute-IDIBELL, Barcelona, Spain ; Centro de Investigación en Red de Salud Mental, Carlos III Health Institute, Barcelona, Spain
| | - José Manuel Menchón
- OCD Clinical and Research Unit, Department of Psychiatry, Hospital de Bellvitge, Barcelona, Spain ; Bellvitge Biomedical Research Institute-IDIBELL, Barcelona, Spain ; Centro de Investigación en Red de Salud Mental, Carlos III Health Institute, Barcelona, Spain ; Department of Clinical Sciences, Bellvitge Campus, University of Barcelona, Barcelona, Spain
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16
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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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17
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Abstract
Obsessive-compulsive disorder (OCD) and related conditions (trichotillomania, pathological skin-picking, pathological nail-biting) are common and disabling. Current treatment approaches fail to help a significant proportion of patients. Multiple tiers of evidence link these conditions with underlying dysregulation of particular cortico-subcortical circuitry and monoamine systems, which represent targets for treatment. Animal models designed to capture aspects of these conditions are critical for several reasons. First, they help in furthering our understanding of neuroanatomical and neurochemical underpinnings of the obsessive-compulsive (OC) spectrum. Second, they help to account for the brain mechanisms by which existing treatments (pharmacotherapy, psychotherapy, deep brain stimulation) exert their beneficial effects on patients. Third, they inform the search for novel treatments. This article provides a critique of key animal models for selected OC spectrum disorders, beginning with initial work relating to anxiety, but moving on to recent developments in domains of genetic, pharmacological, cognitive, and ethological models. We find that there is a burgeoning literature in these areas with important ramifications, which are considered, along with salient future lines of research.
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18
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Nilsson SRO, Somerville EM, Clifton PG. Dissociable effects of 5-HT2C receptor antagonism and genetic inactivation on perseverance and learned non-reward in an egocentric spatial reversal task. PLoS One 2013; 8:e77762. [PMID: 24204954 PMCID: PMC3813744 DOI: 10.1371/journal.pone.0077762] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Accepted: 09/04/2013] [Indexed: 11/19/2022] Open
Abstract
Cognitive flexibility can be assessed in reversal learning tests, which are sensitive to modulation of 5-HT2C receptor (5-HT2CR) function. Successful performance in these tests depends on at least two dissociable cognitive mechanisms which may separately dissipate associations of previous positive and negative valence. The first is opposed by perseverance and the second by learned non-reward. The current experiments explored the effect of reducing function of the 5-HT2CR on the cognitive mechanisms underlying egocentric reversal learning in the mouse. Experiment 1 used the 5-HT2CR antagonist SB242084 (0.5 mg/kg) in a between-groups serial design and Experiment 2 used 5-HT2CR KO mice in a repeated measures design. Animals initially learned to discriminate between two egocentric turning directions, only one of which was food rewarded (denoted CS+, CS-), in a T- or Y-maze configuration. This was followed by three conditions; (1) Full reversal, where contingencies reversed; (2) Perseverance, where the previous CS+ became CS- and the previous CS- was replaced by a novel CS+; (3) Learned non-reward, where the previous CS- became CS+ and the previous CS+ was replaced by a novel CS-. SB242084 reduced perseverance, observed as a decrease in trials and incorrect responses to criterion, but increased learned non-reward, observed as an increase in trials to criterion. In contrast, 5-HT2CR KO mice showed increased perseverance. 5-HT2CR KO mice also showed retarded egocentric discrimination learning. Neither manipulation of 5-HT2CR function affected performance in the full reversal test. These results are unlikely to be accounted for by increased novelty attraction, as SB242084 failed to affect performance in an unrewarded novelty task. In conclusion, acute 5-HT2CR antagonism and constitutive loss of the 5-HT2CR have opposing effects on perseverance in egocentric reversal learning in mice. It is likely that this difference reflects the broader impact of 5HT2CR loss on the development and maintenance of cognitive function.
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Affiliation(s)
- Simon R. O. Nilsson
- School of Psychology, University of Sussex, Brighton, East Sussex, United Kingdom
| | | | - Peter G. Clifton
- School of Psychology, University of Sussex, Brighton, East Sussex, United Kingdom
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19
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Austgen JR, Dantzler HA, Barger BK, Kline DD. 5-hydroxytryptamine 2C receptors tonically augment synaptic currents in the nucleus tractus solitarii. J Neurophysiol 2012; 108:2292-305. [PMID: 22855775 PMCID: PMC3545023 DOI: 10.1152/jn.00049.2012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Accepted: 07/29/2012] [Indexed: 12/20/2022] Open
Abstract
The nucleus tractus solitarii (nTS) is the primary termination and integration point for visceral afferents in the brain stem. Afferent glutamate release and its efficacy on postsynaptic activity within this nucleus are modulated by additional neuromodulators and transmitters, including serotonin (5-HT) acting through its receptors. The 5-HT(2) receptors in the medulla modulate the cardiorespiratory system and autonomic reflexes, but the distribution of the 5-HT(2C) receptor and the role of these receptors during synaptic transmission in the nTS remain largely unknown. In the present study, we examined the distribution of 5-HT(2C) receptors in the nTS and their role in modulating excitatory postsynaptic currents (EPSCs) in monosynaptic nTS neurons in the horizontal brain stem slice. Real-time RT-PCR and immunohistochemistry identified 5-HT(2C) receptor message and protein in the nTS and suggested postsynaptic localization. In nTS neurons innervated by general visceral afferents, 5-HT(2C) receptor activation increased solitary tract (TS)-EPSC amplitude and input resistance and depolarized membrane potential. Conversely, 5-HT(2C) receptor blockade reduced TS-EPSC and miniature EPSC amplitude, as well as input resistance, and hyperpolarized membrane potential. Synaptic parameters in nTS neurons that receive sensory input from carotid body chemoafferents were also attenuated by 5-HT(2C) receptor blockade. Taken together, these data suggest that 5-HT(2C) receptors in the nTS are located postsynaptically and augment excitatory neurotransmission.
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Affiliation(s)
- James R Austgen
- Department of Biomedical Sciences and Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, USA
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20
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Acutely applied MDMA enhances long-term potentiation in rat hippocampus involving D1/D5 and 5-HT2 receptors through a polysynaptic mechanism. Eur Neuropsychopharmacol 2012; 22:584-95. [PMID: 22209363 DOI: 10.1016/j.euroneuro.2011.11.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Revised: 10/12/2011] [Accepted: 11/25/2011] [Indexed: 11/24/2022]
Abstract
3,4-Methylenedioxymethamphetamine (MDMA, ecstasy) is a drug of abuse that induces learning and memory deficit. However, there are no experimental data that correlate the behavioral evidence with models of synaptic plasticity such as long-term potentiation (LTP) or long-term depression (LTD). Using field potential recordings in rat hippocampal slices of young rats, we found that acute application of MDMA enhances LTP in CA3-CA1 synapses without affecting LTD. Using specific antagonists and paired-pulse facilitation protocols we observed that the MDMA-dependent increase of LTP involves presynaptic 5-HT₂ serotonin receptors and postsynaptic D1/D5 dopamine receptors. In addition, the inhibition of PKA suppresses the MDMA-dependent increase in LTP, suggesting that dopamine receptor agonism activates cAMP-dependent intracellular pathways. We propose that MDMA exerts its LTP-altering effect involving a polysynaptic interaction between serotonergic and dopaminergic systems in hippocampal synapses. Our results are compatible with the view that the alterations in hippocampal LTP could be responsible for MDMA-dependent cognitive deficits observed in humans and animals.
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21
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Albelda N, Joel D. Current animal models of obsessive compulsive disorder: an update. Neuroscience 2012; 211:83-106. [PMID: 21925243 DOI: 10.1016/j.neuroscience.2011.08.070] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Revised: 08/29/2011] [Accepted: 08/31/2011] [Indexed: 12/30/2022]
Affiliation(s)
- N Albelda
- Department of Psychology, Tel Aviv University, Ramat-Aviv, Tel Aviv 69978, Israel
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22
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Lalonde R, Fukuchi K, Strazielle C. APP transgenic mice for modelling behavioural and psychological symptoms of dementia (BPSD). Neurosci Biobehav Rev 2012; 36:1357-75. [PMID: 22373961 PMCID: PMC3340431 DOI: 10.1016/j.neubiorev.2012.02.011] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Revised: 02/10/2012] [Accepted: 02/13/2012] [Indexed: 12/17/2022]
Abstract
The discovery of gene mutations responsible for autosomal dominant Alzheimer's disease has enabled researchers to reproduce in transgenic mice several hallmarks of this disorder, notably Aβ accumulation, though in most cases without neurofibrillary tangles. Mice expressing mutated and wild-type APP as well as C-terminal fragments of APP exhibit variations in exploratory activity reminiscent of behavioural and psychological symptoms of Alzheimer dementia (BPSD). In particular, open-field, spontaneous alternation, and elevated plus-maze tasks as well as aggression are modified in several APP transgenic mice relative to non-transgenic controls. However, depending on the precise murine models, changes in open-field and elevated plus-maze exploration occur in either direction, either increased or decreased relative to controls. It remains to be determined which neurotransmitter changes are responsible for this variability, in particular with respect to GABA, 5HT, and dopamine.
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Affiliation(s)
- R Lalonde
- Département de Psychologie, Faculté des Sciences, Université de Rouen, 76821 Mont-Saint-Aignan Cedex, France.
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23
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Schneider H, Fritzky L, Williams J, Heumann C, Yochum M, Pattar K, Noppert G, Mock V, Hawley E. Cloning and expression of a zebrafish 5-HT(2C) receptor gene. Gene 2012; 502:108-17. [PMID: 22521866 DOI: 10.1016/j.gene.2012.03.070] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Revised: 03/23/2012] [Accepted: 03/28/2012] [Indexed: 11/18/2022]
Abstract
The 5-HT(2C) receptor is one of 14 different serotonin (5-HT) receptors that control neural function and behavior. Here, we present the entire sequence of a zebrafish 5-HT(2C) receptor cDNA including the 3' untranslated region and the previously unknown 5' untranslated region. The cloned 5-HT(2C) receptor gene is located on chromosome 7, is approximately 202 kbp long, and contains six exons. The coding region of the gene is 1557 bp long and flanked by a 504 bp 5' UTR and a 1474 bp 3' UTR. The deduced protein sequence of 518 amino acids aligns with orthologs of other vertebrates and is 54% identical to the human and mouse 5-HT(2C) receptor protein sequences. The region of the cDNA that encodes the 2nd cytoplasmic loop of the protein shows a 66% identity with vertebrate orthologs and clearly identifies the gene as a 5-HT(2C) receptor gene. Coupling sites for beta-arrestin and calmodulin are conserved in zebrafish. In-situ hybridization shows that the receptor is expressed in the brain and spinal cord including areas such as the olfactory bulb, the dorsal thalamus, the posterior tuberculum, the hypothalamus and the medulla oblongata. Reverse Transcriptase-PCR experiments indicate that the receptor gene can also be active in other tissues such as skin, ovaries, and axial muscle of adult zebrafish. Expression of the 5-HT(2C) receptor during ontogeny was found as early as 2.5 hpf. Five edited adenines in the region of the human, rat and mouse mRNA that encodes the 2nd cytoplasmic loop are conserved in the zebrafish transcript. However, RNA editing was not detected in the zebrafish. The results characterize the zebrafish 5-HT(2C) receptor gene and gene expression pattern for the first time. The similarities to mammalian 5-HT(2C) receptor genes suggest the use of zebrafish for the study of 5-HT(2C) receptor function in behavior, development and drug discovery.
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Affiliation(s)
- Henning Schneider
- DePauw University, Department of Biology, Greencastle, IN 46135, USA.
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Abstract
Memories for emotionally arousing experiences are typically vivid and persistent. The recurrent, intrusive memories of traumatic events in post-traumatic stress disorder (PTSD) are an extreme example. Stress-responsive neurotransmitters released during emotional arousal are proposed to enhance the consolidation of fear memory. These transmitters may include norepinephrine and epinephrine (NE/E) because stimulating β-adrenergic receptors shortly after training can enhance memory consolidation. However, mice lacking NE/E acquire and consolidate fear memory normally. Here, we show by using pharmacologic and genetic manipulations in mice and rats that NE/E are not essential for classical fear memory consolidation because signaling by the β(2)-adrenergic receptor is redundant with signaling by dopamine at the D(5)-dopaminergic receptor. The intracellular signaling that is stimulated by these receptors to promote consolidation uses distinct G proteins to redundantly activate phospholipase C. The results support recent evidence indicating that blocking β-adrenergic receptors alone shortly after trauma may not be sufficient to prevent PTSD.
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Trakhtenberg EF, Goldberg JL. The role of serotonin in axon and dendrite growth. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2012; 106:105-26. [PMID: 23211461 DOI: 10.1016/b978-0-12-407178-0.00005-3] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The neurotransmitter serotonin (5-hydroxytryptamine, 5-HT) plays multiple roles in the enteric, peripheral, and central nervous systems (CNS). Although its most prominent biological function is as a signal transmission messenger from pre- to postsynaptic neurons, other roles such as shaping brain development and regulating neurite growth have also been described. Here, we review the less well-studied role of 5-HT as a modulator of neurite growth. 5-HT has been shown to regulate neurite growth in multiple systems and species, including in the mammalian CNS. 5-HT predominantly appears to suppress neurite growth, but depending on the model system and 5-HT receptor subtype, in rare cases, it may promote neurite outgrowth and elongation. Failure of axon regeneration in the adult mammalian CNS is a major problem in multiple diseases, and understanding how 5-HT receptors signal opposing effects on neurite growth may lead to novel neuroregenerative therapies, by targeting either 5-HT receptors or their downstream signaling pathways.
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Affiliation(s)
- Ephraim F Trakhtenberg
- Bascom Palmer Eye Institute, Interdisciplinary Stem Cell Institute, Neuroscience Program, University of Miami Miller School of Medicine, Miami, FL 33136, USA.
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Marchetti C, Tafi E, Marie H. Viral-mediated expression of a constitutively active form of cAMP response element binding protein in the dentate gyrus increases long term synaptic plasticity. Neuroscience 2011; 190:21-6. [PMID: 21712073 DOI: 10.1016/j.neuroscience.2011.06.040] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2011] [Revised: 06/10/2011] [Accepted: 06/10/2011] [Indexed: 01/14/2023]
Abstract
The transcription factor cAMP response element binding protein (CREB) is a key player in synaptic plasticity and learning. Phosphorylation of CREB induced by neuronal activity leads to gene transcription, a process thought to contribute to memory formation. We have previously reported that increasing CREB activity in glutamatergic CA1 pyramidal neurons or in dentate gyrus (DG) granule cells is sufficient to enhance hippocampal-dependent memory formation. This enhancement correlates with an increase in CA1 glutamatergic synaptic plasticity. However, the effects of increasing CREB activity on DG glutamatergic plasticity have not been investigated. To address this issue, we boosted CREB-dependent transcription in DG granule cells in vivo via viral mediated expression of a constitutively active form of CREB (CREBCA). Using in vitro extracellular field recordings of infected slices, we observed an increase in long-term potentiation (LTP) while short-term plasticity and basic synaptic transmission remained unaffected. These data demonstrate that boosting CREB activity in DG granule cells is sufficient to enhance LTP and suggest that this enhancement participates in the formation of better memories.
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Affiliation(s)
- C Marchetti
- Laboratory of Molecular Mechanisms of Synaptic Plasticity, European Brain Research Institute, Via del Fosso di Fiorano 64, 00143 Rome, Italy.
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Klempin F, Babu H, De Pietri Tonelli D, Alarcon E, Fabel K, Kempermann G. Oppositional effects of serotonin receptors 5-HT1a, 2, and 2c in the regulation of adult hippocampal neurogenesis. Front Mol Neurosci 2010; 3. [PMID: 20721314 PMCID: PMC2922940 DOI: 10.3389/fnmol.2010.00014] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2009] [Accepted: 06/14/2010] [Indexed: 02/04/2023] Open
Abstract
Serotonin (5-HT) appears to play a major role in controlling adult hippocampal neurogenesis and thereby it is relevant for theories linking failing adult neurogenesis to the pathogenesis of major depression and the mechanisms of action of antidepressants. Serotonergic drugs lacked acute effects on adult neurogenesis in many studies, which suggested a surprisingly long latency phase. Here we report that the selective serotonin reuptake inhibitor fluoxetine, which has no acute effect on precursor cell proliferation, causes the well-described increase in net neurogenesis upon prolonged treatment partly by promoting the survival and maturation of new postmitotic neurons. We hypothesized that this result is the cumulative effect of several 5-HT-dependent events in the course of adult neurogenesis. Thus, we used specific agonists and antagonists to 5-HT1a, 2, and 2c receptor subtypes to analyze their impact on different developmental stages. We found that 5-HT exerts acute and opposing effects on proliferation and survival or differentiation of precursor cells by activating the diverse receptor subtypes on different stages within the neuronal lineage in vivo. This was confirmed in vitro by demonstrating that 5-HT1a receptors are involved in self-renewal of precursor cells, whereas 5-HT2 receptors effect both proliferation and promote neuronal differentiation. We propose that under acute conditions 5-HT2 effects counteract the positive proliferative effect of 5-HT1a receptor activation. However, prolonged 5-HT2c receptor activation fosters an increase in late-stage progenitor cells and early postmitotic neurons, leading to a net increase in adult neurogenesis. Our data indicate that serotonin does not show effect latency in the adult dentate gyrus. Rather, the delayed response to serotonergic drugs with respect to endpoints downstream of the immediate receptor activity is largely due to the initially antagonistic and un-balanced action of different 5-HT receptors.
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Zafeiriou DI, Ververi A, Vargiami E. The serotonergic system: its role in pathogenesis and early developmental treatment of autism. Curr Neuropharmacol 2010; 7:150-7. [PMID: 19949574 PMCID: PMC2730007 DOI: 10.2174/157015909788848848] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2008] [Revised: 01/15/2009] [Accepted: 03/27/2009] [Indexed: 11/22/2022] Open
Abstract
Autism is a severe childhood disorder already presenting in the first 3 years of life and, therefore, strongly correlated with neurodevelopmental alterations in prenatal, as well as postnatal period. Neurotransmitters hold a pivotal role in development by providing the stimulation needed for synapses and neuronal networks to be formed during the critical period of neuroplasticity. Aberrations of the serotonergic system modify key processes in the developing brain and are strongly implicated in the pathophysiology of developmental disorders. Evidence for the role of serotonin in autism emerges from neuropathological, imaging and genetic studies. Due to its developmental arrest, autism requires early intervention that would, among others, target the disrupted serotonergic system and utilize brain plasticity to elicit clinically important brain changes in children.
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Affiliation(s)
- D I Zafeiriou
- 1st Department of Pediatrics, Aristotle University of Thessaloniki, Greece.
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Hill RA, Murray SS, Halley PG, Binder MD, Martin SJ, van den Buuse M. Brain-derived neurotrophic factor expression is increased in the hippocampus of 5-HT2C receptor knockout mice. Hippocampus 2010; 21:434-45. [DOI: 10.1002/hipo.20759] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Sierksma AS, van den Hove DL, Steinbusch HW, Prickaerts J. Major depression, cognitive dysfunction and Alzheimer's disease: Is there a link? Eur J Pharmacol 2010; 626:72-82. [DOI: 10.1016/j.ejphar.2009.10.021] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2009] [Revised: 09/29/2009] [Accepted: 10/06/2009] [Indexed: 11/30/2022]
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Upregulation of 5-HT2C receptors in hippocampus of pilocarpine-induced epileptic rats: antagonism by Bacopa monnieri. Epilepsy Behav 2009; 16:225-30. [PMID: 19700373 DOI: 10.1016/j.yebeh.2009.07.031] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2009] [Revised: 07/17/2009] [Accepted: 07/18/2009] [Indexed: 01/30/2023]
Abstract
Emotional disturbances, depressive mood, anxiety, aggressive behavior, and memory impairment are the common psychiatric features associated with temporal lobe epilepsy (TLE). The present study was carried out to investigate the role of Bacopa monnieri extract in hippocampus of pilocarpine-induced temporal lobe epileptic rats through the 5-HT(2C) receptor in relation to depression. Our results showed upregulation of 5-HT(2C) receptors with a decreased affinity in hippocampus of pilocarpine-induced epileptic rats. Also, there was an increase in 5-HT(2C) gene expression and inositol triphosphate content in epileptic hippocampus. Carbamazepine and B. monnieri treatments reversed the alterations in 5-HT(2C) receptor binding, gene expression, and inositol triphosphate content in treated epileptic rats as compared to untreated epileptic rats. The forced swim test confirmed the depressive behavior pattern during epilepsy that was nearly completely reversed by B. monnieri treatment.
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32
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Lalonde R, Strazielle C. Relations between open-field, elevated plus-maze, and emergence tests in C57BL/6J and BALB/c mice injected with GABA- and 5HT-anxiolytic agents. Fundam Clin Pharmacol 2009; 24:365-76. [PMID: 19735300 DOI: 10.1111/j.1472-8206.2009.00772.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Two 5HT(1A) receptor agonists and chlordiazepoxide were examined in open-field, elevated plus maze, and emergence tests. At doses with no effect in the open-field, chlordiazepoxide increased open and open/total arm visits as well as open arm duration in the elevated plus maze, whereas 5HT(1A) receptor agonists showed an anxiolytic response on a single measure. The anxiolytic action of chlordiazepoxide was limited to the less active BALB/c strain. Unlike the 5HT(1A) receptor agonists, chlordiazepoxide was also anxiolytic in the emergence test, once again only in BALB/c and not C57BL/6J mice. Significant correlations were found between emergence latencies and specific indicators of anxiety in the elevated plus-maze in chlordiazepoxide-treated but not in mice treated with buspirone and 8-OH-DPAT. These results indicate that elevated plus-maze and emergence tests depend on benzodiazepine receptors. In contrast, 5HT(1A) receptor agonists were ineffective in the emergence test and no correlation was found between emergence latencies and specific indicators of anxiety in the elevated plus-maze. Though superficially similar, the emergence test seems to tap into a partially separate facet of anxiety.
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Affiliation(s)
- Robert Lalonde
- Centre Hospitalier de l'Université de Montréal/St-Luc, Unité de Recherche en Sciences Neurologiques, Montréal, Québec, Canada H2X 3J4.
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33
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Lalonde R, Strazielle C. Exploratory activity and motor coordination in old versus middle-aged C57BL/6J mice. Arch Gerontol Geriatr 2009; 49:39-42. [DOI: 10.1016/j.archger.2008.04.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2007] [Revised: 04/21/2008] [Accepted: 04/23/2008] [Indexed: 10/22/2022]
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PSD-95 is essential for hallucinogen and atypical antipsychotic drug actions at serotonin receptors. J Neurosci 2009; 29:7124-36. [PMID: 19494135 DOI: 10.1523/jneurosci.1090-09.2009] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Here, we report that postsynaptic density protein of 95 kDa (PSD-95), a postsynaptic density scaffolding protein, classically conceptualized as being essential for the regulation of ionotropic glutamatergic signaling at the postsynaptic membrane, plays an unanticipated and essential role in mediating the actions of hallucinogens and atypical antipsychotic drugs at 5-HT(2A) and 5-HT(2C) serotonergic G-protein-coupled receptors. We show that PSD-95 is crucial for normal 5-HT(2A) and 5-HT(2C) expression in vivo and that PSD-95 maintains normal receptor expression by promoting apical dendritic targeting and stabilizing receptor turnover in vivo. Significantly, 5-HT(2A)- and 5-HT(2C)-mediated downstream signaling is impaired in PSD-95(null) mice, and the 5-HT(2A)-mediated head-twitch response is abnormal. Furthermore, the ability of 5-HT(2A) inverse agonists to normalize behavioral changes induced by glutamate receptor antagonists is abolished in the absence of PSD-95 in vivo. These results demonstrate that PSD-95, in addition to the well known role it plays in scaffolding macromolecular glutamatergic signaling complexes, profoundly modulates metabotropic 5-HT(2A) and 5-HT(2C) receptor function.
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35
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Zhong P, Liu W, Gu Z, Yan Z. Serotonin facilitates long-term depression induction in prefrontal cortex via p38 MAPK/Rab5-mediated enhancement of AMPA receptor internalization. J Physiol 2008; 586:4465-79. [PMID: 18653660 DOI: 10.1113/jphysiol.2008.155143] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The serotonin system in prefrontal cortex (PFC) is critically involved in the regulation of cognition and emotion. To understand the cellular mechanisms underlying its physiological actions, we investigated the role of serotonin in regulating synaptic plasticity in PFC circuits. We found that tetanic stimuli coupled to bath application of serotonin induced long-term depression (LTD) at excitatory synapses of PFC pyramidal neurons. This effect was mediated by 5-HT(2A/C) receptors and was independent of NMDA receptor activation. A group I metabotropic glutamate receptor (mGluR) antagonist blocked the LTD induction by serotonin + tetani, and co-application of a group I mGluR agonist and serotonin, but not application of either drug alone, induced LTD without tetani. The effect of serotonin on LTD was blocked by selective inhibitors of p38 mitogen-activated protein kinase (MAPK), but not p42/44 MAPK. Biochemical evidence also indicated that serotonin and a group I mGluR agonist synergistically activated p38 MAPK in PFC slices. The serotonin-facilitated LTD induction was prevented by blocking the activation of the small GTPase Rab5, as well as by blocking the clathrin-dependent internalization of AMPA receptors with postsynaptic injection of a dynamin inhibitory peptide, while it was unaffected by manipulating the cytoskeleton. Interestingly, in animals exposed to acute stress, the LTD induction by serotonin + tetani was significantly impaired. Taken together, these results suggest that serotonin, by cooperating with mGluRs, regulates synaptic plasticity through a mechanism dependent on p38 MAPK/Rab5-mediated enhancement of AMPA receptor internalization in a clathrin/dynamin-dependent manner. It provides a potential mechanism underlying the role of serotonin in controlling emotional and cognitive processes that are mediated by synaptic plasticity in PFC neurons.
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Affiliation(s)
- Ping Zhong
- Department of Physiology and Biophysics, State University of New York at Buffalo, 124 Sherman Hall, Buffalo, NY 14214, USA
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36
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Lalonde R, Strazielle C. Relations between open-field, elevated plus-maze, and emergence tests as displayed by C57/BL6J and BALB/c mice. J Neurosci Methods 2008; 171:48-52. [PMID: 18358538 DOI: 10.1016/j.jneumeth.2008.02.003] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2007] [Revised: 01/29/2008] [Accepted: 02/01/2008] [Indexed: 11/18/2022]
Abstract
The relations between open-field, elevated plus-maze, and emergence tests were examined in two strains of mice. In the open-field, C57BL/6J mice had more ambulatory movements and rears but not stereotyped movements relative to BALB/c. In addition, C57BL/6J mice entered more often than BALB/c into enclosed and open arms of the elevated plus-maze. When placed inside a large enclosure, C57BL/6J mice emerged more quickly than BALB/c from a small toy object. In the entire series of mice, ambulation and rears in the open-field were linearly correlated with open and enclosed arm visits in the elevated plus-maze. Ambulatory movements and rears were also correlated with emergence latencies. In contrast, stereotyped movements were correlated with emergence latencies, but not with any elevated plus-maze value. These results specify the extent and limits of association between the three tests.
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Affiliation(s)
- R Lalonde
- Université de Rouen, Faculté de Sciences, Centre Hospitalier de l'Université de Montréal/St-Luc, Unité de Recherche en Sciences Neurologiques, Montréal, Québec, Canada H2X 3J4.
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37
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Bethea TC, Sikich L. Early pharmacological treatment of autism: a rationale for developmental treatment. Biol Psychiatry 2007; 61:521-37. [PMID: 17276749 PMCID: PMC2553755 DOI: 10.1016/j.biopsych.2006.09.021] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2006] [Revised: 09/02/2006] [Accepted: 09/24/2006] [Indexed: 11/25/2022]
Abstract
Autism is a dynamic neurodevelopmental syndrome in which disabilities emerge during the first three postnatal years and continue to evolve with ongoing development. We briefly review research in autism describing subtle changes in molecules important in brain development and neurotransmission, in morphology of specific neurons, brain connections, and in brain size. We then provide a general schema of how these processes may interact with particular emphasis on neurotransmission. In this context, we present a rationale for utilizing pharmacologic treatments aimed at modifying key neurodevelopmental processes in young children with autism. Early treatment with selective serotonin reuptake inhibitors (SSRIs) is presented as a model for pharmacologic interventions because there is evidence in autistic children for reduced brain serotonin synthesis during periods of peak synaptogenesis; serotonin is known to enhance synapse refinement; and exploratory studies with these agents in autistic children exist. Additional hypothetical developmental interventions and relevant published clinical data are described. Finally, we discuss the importance of exploring early pharmacologic interventions within multiple experimental settings in order to develop effective treatments as quickly as possible while minimizing risks.
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Affiliation(s)
- Terrence C Bethea
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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38
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Joel D. Current animal models of obsessive compulsive disorder: a critical review. Prog Neuropsychopharmacol Biol Psychiatry 2006; 30:374-88. [PMID: 16457927 DOI: 10.1016/j.pnpbp.2005.11.006] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 11/02/2005] [Indexed: 12/12/2022]
Abstract
During the last 30 years there have been many attempts to develop animal models of obsessive compulsive disorder (OCD), in the hope that they may provide a route for furthering our understanding and treatment of this disorder. The present paper reviews current genetic, pharmacological and behavioral animal models of OCD, and evaluates their face validity (derived from phenomenological similarity between the behavior in the animal model and the specific symptoms of the human condition), predictive validity (derived from similarity in response to treatment) and construct validity (derived from similarity in the underlying mechanisms--physiological or psychological).
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Affiliation(s)
- Daphna Joel
- Department of Psychology, Tel Aviv University, Ramat-Aviv, Tel Aviv 69978, Israel.
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39
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Millan MJ. Serotonin 5-HT2C receptors as a target for the treatment of depressive and anxious states: focus on novel therapeutic strategies. Therapie 2006; 60:441-60. [PMID: 16433010 DOI: 10.2515/therapie:2005065] [Citation(s) in RCA: 214] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Serotonin (5-HT)2C receptors play an important role in the modulation of monoaminergic transmission, mood, motor behaviour, appetite and endocrine secretion, and alterations in their functional status have been detected in anxiodepressive states. Further, 5-HT2C sites are involved in the actions of several classes of antidepressant. At the onset of treatment, indirect activation of 5-HT2C receptors participates in the anxiogenic effects of selective 5-HT reuptake inhibitors (SSRIs) as well as their inhibition of sleep, sexual behaviour and appetite. Conversely, progressive down-regulation of 5-HT2C receptors parallels the gradual onset of clinical efficacy of SSRIs. Other antidepressants, such as nefazodone or mirtazapine, act as direct antagonists of 5-HT2C receptors. These observations underpin interest in 5-HT2C receptor blockade as a strategy for treating depressive and anxious states. This notion is supported by findings that 5-HT2C receptor antagonists stimulate dopaminergic and adrenergic pathways, exert antidepressant and anxiolytic actions in behavioural paradigms, and favour sleep and sexual function. In addition to selective antagonists, novel strategies for exploitation of 5-HT2C receptors embrace inverse agonists, allosteric modulators, ligands of homo/heterodimers, modulators of interactions with 'postsynaptic proteins', dual melatonin agonists/5-HT2C receptor antagonists and mixed 5-HT2C/alpha2-adrenergic antagonists. Intriguingly, there is evidence that stimulation of regionally discrete populations of 5-HT2C receptors is effective in certain behavioural models of antidepressant activity, and promotes neurogenesis in the hippocampus. This article explains how these ostensibly paradoxical actions of 5-HT2C antagonists and agonists can be reconciled and discusses both established and innovative strategies for the exploitation of 5-HT2C receptors in the improved management of depressed and anxious states.
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Pitsikas N, Sakellaridis N. The 5-HT2C receptor antagonist RO 60-0491 counteracts rats' retention deficits in a recognition memory task. Brain Res 2005; 1054:200-2. [PMID: 16040008 DOI: 10.1016/j.brainres.2005.06.057] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2005] [Revised: 06/17/2005] [Accepted: 06/25/2005] [Indexed: 11/20/2022]
Abstract
The effects of the 5-HT2C receptor antagonist RO 60-0491 on recognition memory were investigated in the rat by using the object recognition task. Post-training administration of RO 60-0491 at 3 mg/kg, but not at 1 mg/kg, counteracted rats' performance deficits in the object recognition task, suggesting that this 5-HT2C receptor antagonist compound modulates storage and/or retrieval of information.
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Affiliation(s)
- Nikolaos Pitsikas
- Department of Pharmacology, School of Medicine, University of Thessaly, 22, Papakiriazi str., 412-22 Larissa, Greece.
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42
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Abstract
The prevalence of dementia is growing in developed countries where elderly patients are increasing in numbers. Neurotransmission modulation is one approach to the treatment of dementia. Cholinergic precursors, anticholinesterases, nicotine receptor agonists and muscarinic M(2) receptor antagonists are agents that enhance cholinergic neurotransmission and that depend on having some intact cholinergic innervation to be effective in the treatment of dementia. The cholinergic precursor choline alfoscerate may be emerging as a potential useful drug in the treatment of dementia, with few adverse effects. Of the anticholinesterases, donepezil, in addition to having a similar efficacy to tacrine in mild-to-moderate Alzheimer's disease (AD), appears to have major advantages; its use is associated with lower drop-out rates in clinical trials, a lower incidence of cholinergic-like side effects and no liver toxicity. Rivastigmine is efficacious in the treatment in dementia with Lewy bodies, a condition in which the other anticholinesterases have not been tested extensively to date. Galantamine is an anticholinesterase and also acts as an allosteric potentiating modulator at nicotinic receptors to increase the release of acetylcholine. Pooled data from clinical trials of patients with mild-to-moderate AD suggest that the benefits and safety profile of galantamine are similar to those of the anticholinesterases. Selective nicotine receptor agonists are being developed that enhance cognitive performance without influencing autonomic and skeletal muscle function, but these have not yet entered clinical trial for dementia. Unlike the cholinergic enhancers, the M(1) receptor agonists do not depend upon intact cholinergic nerves but on intact M(1) receptors for their action, which are mainly preserved in AD and dementia with Lewy bodies. The M(1) receptor-selective agonists developed to date have shown limited efficacy in clinical trials and have a high incidence of side effects. A major recent advancement in the treatment of dementia is memantine, a non-competitive antagonist at NMDA receptors. Memantine is beneficial in the treatment of severe and moderate-to-severe AD and may also be of some benefit in the treatment of mild-to-moderate vascular dementia. Drugs that modulate 5-HT, somatostatin and noradrenergic neurotransmission are also being considered for the treatment of dementia.
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Affiliation(s)
- Sheila A Doggrell
- School of Biomedical Sciences, the University of Queensland, QLD 4072, Australia
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Normann C, Clark K. Selective modulation of Ca2+ influx pathways by 5-HT regulates synaptic long-term plasticity in the hippocampus. Brain Res 2005; 1037:187-93. [PMID: 15777768 DOI: 10.1016/j.brainres.2005.01.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2004] [Revised: 12/22/2004] [Accepted: 01/01/2005] [Indexed: 10/25/2022]
Abstract
Both long-term potentiation (LTP) and long-term depression (LTD) can be induced in the Schaffer collateral-CA1 synapse of the hippocampus either by repetitive stimulation of afferent fibres with the frequency of the stimulation determining the polarity of the response or by associative pairing of pre- and postsynaptic activity. An increase in postsynaptic intracellular Ca(2+) concentration is an important signal for the induction of long-term synaptic plasticity. In patch-clamp experiments on hippocampal brain slices, we tested the modulation of different forms of synaptic plasticity by the neurotransmitter serotonin (5-HT) which is known to inhibit high-voltage activated Ca(2+) channels. 1 microM of 5-HT inhibited homosynaptic LTD induced by low frequency stimulation. This effect of 5-HT could be blocked by the selective 5-HT(1A) antagonist WAY 100635. Low frequency-induced LTD is both dependent on Ca(2+) influx through NMDA receptors and high-voltage activated Ca(2+) channels. It was blocked by the NMDA-receptor antagonist D-AP5 and by the N-type Ca(2+) channel antagonist omega-conotoxin GIVA. Tetanus induced LTP was not affected by low concentrations of 5-HT, whereas depotentiation of LTP by asynchronous pairing of EPSPs and postsynaptic action potentials was completely abolished with 5-HT in the bath solution. We conclude that those forms of plasticity which depend on Ca(2+) influx via high-voltage activated Ca(2+) channels are subject to modulation by 5-HT. This might be a relevant mechanism by which 5-HT modifies basic network properties in the brain.
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Affiliation(s)
- Claus Normann
- Department of Psychiatry, University of Freiburg, Hauptstr. 5, D-79104 Freiburg, Germany.
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Nagai T, Yamada K, Nabeshima T. [Behavioral approaches for analyzing emotionality in mutant mice]. Nihon Yakurigaku Zasshi 2005; 125:71-6. [PMID: 15812135 DOI: 10.1254/fpj.125.71] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
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Wehner JM, Radcliffe RA. Cued and Contextual Fear Conditioning in Mice. ACTA ACUST UNITED AC 2004; Chapter 8:Unit 8.5C. [DOI: 10.1002/0471142301.ns0805cs27] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Lalonde R, Dumont M, Paly E, London J, Strazielle C. Characterization of hemizygous SOD1/wild-type transgenic mice with the SHIRPA primary screen and tests of sensorimotor function and anxiety. Brain Res Bull 2004; 64:251-8. [PMID: 15464862 DOI: 10.1016/j.brainresbull.2004.07.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2003] [Revised: 06/21/2004] [Accepted: 07/21/2004] [Indexed: 10/26/2022]
Abstract
SOD1 is one of several overexpressed genes in Down's syndrome. In order to dissect genetic causes of the syndrome, hemizygous human wild-type SOD1 transgenic mice were compared to FVB/N non-transgenic controls at 3 months of age in the SHIRPA primary screen of neurologic function as well as in tests of motor activity and coordination. The responsiveness of SOD1/wt transgenic mice to visual and somatosensory stimuli was reduced in placing, pinna, corneal, and toe-pinch tests. In addition, SOD1/wt transgenic mice crossed fewer segments on a stationary beam. On the contrary, there was no intergroup difference for motor activity and anxiety in open-field and emergence tests and for latencies before falling on the stationary beam, coat-hanger, and rotorod. These results indicate mild deficits in sensorimotor responsiveness in a mouse model expressing human SOD1 and that the overexpressed gene may be responsible for some Down symptoms.
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Affiliation(s)
- R Lalonde
- Faculté de Médecine et de Pharmacie, Université de Rouen, INSERM U614, Bâtiment de Recherche, 22 bld Gambetta, Salle 1D18, 76183 Rouen, Cedex, France.
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Weitzdoerfer R, Pollak A, Lubec B. Perinatal asphyxia in the rat has lifelong effects on morphology, cognitive functions, and behavior. Semin Perinatol 2004; 28:249-56. [PMID: 15565784 DOI: 10.1053/j.semperi.2004.08.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Perinatal asphyxia (PA) is a major determinant of neurological morbidity and mortality in the neonatal period. Many studies have been investigating neurological deficits following PA, including seizures, cerebral palsy, mental retardation, as well as psychiatric deficits. Most research performed so far has been focusing on acute or subacute sequelae and has uncovered a variety of morphological, neurochemical, behavioral, and cognitive changes following PA. However, information on long-term sequelae of animals that underwent a period of PA is scanty. Perinatally asphyxiated rats at the end of their life span present with immunohistochemical and synaptic changes as well as changes in brain protein expression. Furthermore, deficits in cognitive function tested in the Morris water maze and changes in social behavior were described. In this review, we are summarizing and discussing reported effects of global PA on morphology, cognitive functions, and behavior in rats at the end of their life span.
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Okada M, Northup JK, Ozaki N, Russell JT, Linnoila M, Goldman D. Modification of human 5-HT(2C) receptor function by Cys23Ser, an abundant, naturally occurring amino-acid substitution. Mol Psychiatry 2004; 9:55-64. [PMID: 14699441 DOI: 10.1038/sj.mp.4001357] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A human serotonin (5-HT)(2C) receptor gene polymorphism leads to the substitution of cysteine for serine at codon 23 (Cys23Ser); the frequency of the Ser23 allele in unrelated Caucasians is approximately 0.13. In the present study, we assessed whether Cys23Ser could affect receptor function. The two alleles were functionally compared following expression in COS-7 cells. The constitutive activity of the receptor in an in situ reconstitution system was also evaluated following expression of each allele in Sf9 cells. Using radioligands, Ser23-expressed membranes showed reduced high-affinity binding to meta-chlorophenylpiperazine (m-CPP) and 5-HT. Although the amplitude of the 5-HT-induced intracellular Ca(2+) peak did not differ between the alleles, Ser23 required higher 5-HT concentrations to elicit the same response. These differences might be due to more extensive desensitization in the Ser23 form. In the in situ reconstitution system, the 5-HT(2C) receptor displayed considerable constitutive activity, with the Ser23 allele being significantly higher in this regard than the Cys23 form. After prolonged serum deprivation in order to resensitize the receptor, four of the 15 cells expressing Ser23 showed abnormally higher m-CPP-induced sensitivity of the Ca(2+) response. These results indicate that the Ser23 allele may be constitutively more active than Cys23. Thus, Ser23 appears to be an abundant candidate allele capable of directly influencing inter-individual variation in behavior, susceptibility to mental disorder, and response to drugs including atypical antipsychotic and some antidepressant drugs that are potent 5-HT(2C) inverse agonists or antagonists.
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Affiliation(s)
- M Okada
- Department of Public Health, Faculty of Medicine, Osaka City University, Osaka, Japan.
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Lu L, Bao G, Chen H, Xia P, Fan X, Zhang J, Pei G, Ma L. Modification of hippocampal neurogenesis and neuroplasticity by social environments. Exp Neurol 2003; 183:600-9. [PMID: 14552901 DOI: 10.1016/s0014-4886(03)00248-6] [Citation(s) in RCA: 159] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Synaptic plasticity and neurogenesis in the brain are affected by environmental stimuli. The present study was designed to investigate the effects of social environments on learning and memory, neurogenesis, and neuroplasticity. Twenty-two-day-old rats were housed in isolation or in groups for 4 or 8 weeks and injected intraperitoneally with bromodeoxyuridine to detect proliferation among progenitor cells. The animals were also tested for learning in a water maze and for hippocampal CA1 long-term potentiation in vivo and in vitro. The results show that the number of newborn neurons in the dentate gyrus and the learning in a water maze decreased significantly in rats reared in isolation for 4 or 8 weeks, as compared with grouped controls. Induction of long-term potentiation in the CA1 area of rat hippocampus in vivo and in vitro was also significantly reduced by isolation. Furthermore, the effects of isolation rearing on spatial learning, hippocampal neurogenesis, and long-term potentiation could be reversed by subsequent group rearing. These findings demonstrated that social environments can modify neurogenesis and synaptic plasticity in adult hippocampal regions, which is associated with alterations in spatial learning and memory.
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Affiliation(s)
- Lin Lu
- National Laboratory of Medical Neurobiology, Shanghai Medical College and Institutes of Brain Science, Fudan University, 138 Yi Xue Yuan Road, 200032, Shanghai, China
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McGregor IS, Clemens KJ, Van der Plasse G, Li KM, Hunt GE, Chen F, Lawrence AJ. Increased anxiety 3 months after brief exposure to MDMA ("Ecstasy") in rats: association with altered 5-HT transporter and receptor density. Neuropsychopharmacology 2003; 28:1472-84. [PMID: 12700695 DOI: 10.1038/sj.npp.1300185] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Male Wistar rats were treated with 3,4-methylenedioxymethamphetamine (MDMA, "Ecstasy") using either a high dose (4 x 5 mg/kg over 4 h) or low dose (1 x 5 mg/kg over 4 h) regimen on each of 2 consecutive days. After 10 weeks, rats were tested in the social interaction and emergence tests of anxiety. Rats previously given either of the MDMA dose regimens were significantly more anxious on both tests. After behavioral testing, and 3 months after the MDMA treatment, the rats were killed and their brains examined. Rats given the high-, but not the low-, dose MDMA treatment regimen exhibited significant loss of 5-hydroxytryptamine (5-HT) and 5-HIAA in the amygdala, hippocampus, striatum, and cortex. Quantitative autoradiography showed loss of SERT binding in cortical, hippocampal, thalamic, and hypothalamic sites with the high-dose MDMA regime, while low-dose MDMA only produced significant loss in the medial hypothalamus. Neither high- nor low-dose MDMA affected 5HT(1A) receptor density. High-dose MDMA increased 5HT(1B) receptor density in the nucleus accumbens and lateral septum but decreased binding in the globus pallidus, insular cortex and medial thalamus. Low-dose MDMA decreased 5HT(1B) receptor density in the hippocampus, globus pallidus, and medial thalamus. High-dose MDMA caused dramatic decreases in cortical, striatal, thalamic, and hypothalamic 5HT(2A)/(2C) receptor density, while low-dose MDMA tended to produce similar effects but only significantly in the piriform cortex. These data suggest that even brief, relatively low-dose MDMA exposure can produce significant, long-term changes in 5-HT receptor and transporter function and associated emotional behavior. Interestingly, long-term 5-HT depletion may not be necessary to produce lasting effects on anxiety-like behavior after low-dose MDMA.
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Affiliation(s)
- Iain S McGregor
- School of Psychology, University of Sydney, A19, NSW 2006, Australia.
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