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de Cates AN, Martens MAG, Wright LC, Gibson D, Spitz G, Gould van Praag CD, Suri S, Cowen PJ, Murphy SE, Harmer CJ. 5-HT 4 Receptor Agonist Effects on Functional Connectivity in the Human Brain: Implications for Procognitive Action. BIOLOGICAL PSYCHIATRY. COGNITIVE NEUROSCIENCE AND NEUROIMAGING 2023; 8:1124-1134. [PMID: 37098409 PMCID: PMC10914664 DOI: 10.1016/j.bpsc.2023.03.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 03/02/2023] [Accepted: 03/31/2023] [Indexed: 04/27/2023]
Abstract
BACKGROUND Cognitive deficits are often comorbid with mood disorders and can cause significant functional impairment even after resolution of the primary mood symptoms. We do not currently have pharmacological treatments that adequately address these deficits. 5-HT4 receptor agonists show promise as potential procognitive agents in animal and early human translational studies. Optimal cognitive performance in humans is directly associated with appropriate functional connectivity between specific resting-state neural networks. However, so far the effect of 5-HT4 receptor agonism on resting-state functional connectivity (rsFC) in the brain in humans is unknown. METHODS We collected resting-state functional magnetic resonance imaging scans from 50 healthy volunteers, of whom 25 received 6 days × 1 mg prucalopride (a highly selective 5-HT4 receptor agonist) and 25 received placebo in a randomized double-blind design. RESULTS Network analyses identified that participants in the prucalopride group had enhanced rsFC between the central executive network and the posterior/anterior cingulate cortex. Seed analyses also showed greater rsFC between the left and right rostral anterior cingulate cortex and the left lateral occipital cortex, and reduced rsFC between the hippocampus and other default mode network regions. CONCLUSIONS Similar to other potentially procognitive medications, low-dose prucalopride in healthy volunteers appeared to enhance rsFC between regions involved in cognitive networks and reduce rsFC within the default mode network. This suggests a mechanism for the behavioral cognitive enhancement previously seen with 5-HT4 receptor agonists in humans and supports the potential for 5-HT4 receptor agonists to be used in clinical psychiatric populations.
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Affiliation(s)
- Angharad N de Cates
- Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford, United Kingdom; Oxford Health NHS Foundation Trust, Warneford Hospital, Oxford, United Kingdom.
| | - Marieke A G Martens
- Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford, United Kingdom; Oxford Health NHS Foundation Trust, Warneford Hospital, Oxford, United Kingdom
| | - Lucy C Wright
- Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford, United Kingdom; Oxford Health NHS Foundation Trust, Warneford Hospital, Oxford, United Kingdom
| | - Daisy Gibson
- Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford, United Kingdom; Oxford Health NHS Foundation Trust, Warneford Hospital, Oxford, United Kingdom
| | - Gershon Spitz
- Monash-Epworth Rehabilitation Research Centre, Turner Institute for Brain and Mental Health, School of Psychological Sciences, Monash University, Clayton, Victoria, Australia; Department of Neuroscience, Central Clinical School, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria, Australia
| | - Cassandra D Gould van Praag
- Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford, United Kingdom; Oxford Centre for Human Brain Activity and Oxford Centre for Functional MRI of the Brain, Wellcome Centre for Integrative Neuroimaging, Department of Psychiatry, University of Oxford, Oxford, United Kingdom
| | - Sana Suri
- Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford, United Kingdom; Oxford Centre for Human Brain Activity and Oxford Centre for Functional MRI of the Brain, Wellcome Centre for Integrative Neuroimaging, Department of Psychiatry, University of Oxford, Oxford, United Kingdom
| | - Philip J Cowen
- Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford, United Kingdom; Oxford Health NHS Foundation Trust, Warneford Hospital, Oxford, United Kingdom
| | - Susannah E Murphy
- Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford, United Kingdom; Oxford Health NHS Foundation Trust, Warneford Hospital, Oxford, United Kingdom
| | - Catherine J Harmer
- Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford, United Kingdom; Oxford Health NHS Foundation Trust, Warneford Hospital, Oxford, United Kingdom; Oxford Centre for Human Brain Activity and Oxford Centre for Functional MRI of the Brain, Wellcome Centre for Integrative Neuroimaging, Department of Psychiatry, University of Oxford, Oxford, United Kingdom
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Nirogi R, Grandhi VR, Medapati R, Ganuga N, Abraham R, Thentu JB, Palacharla VRC, Petlu S, Srirangavaram M, Subramanian R, Ravella SR, Gagginapally SR, Benade V, Jayarajan P, Mohammed AR. Usmarapride (SUVN-D4010), a 5-HT4 receptor partial agonist for the potential treatment of Alzheimer's disease: Behavioural, neurochemical and pharmacological profiling. Eur J Pharmacol 2023; 947:175625. [PMID: 36997046 DOI: 10.1016/j.ejphar.2023.175625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2022] [Revised: 02/24/2023] [Accepted: 02/24/2023] [Indexed: 03/30/2023]
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disorder which affects cognitive functions with negative impact on day to day activities and an ultimate loss of independent living. Current standard of care (SOC) for AD, viz. donepezil, rivastigmine, galantamine, memantine etc. either alone or in combination show modest efficacy without changing the course of the disease. On prolonged treatment, side effects are more common with an eventual loss of efficacy. Aducanumab, a monoclonal antibody is a disease modifying therapeutic agent targeting the toxic amyloid beta (Aβ) proteins for its clearance. However, it is found to have only modest efficacy in AD patients and its approval by FDA is controversial. Alternate, effective and safe therapeutics are need of the hour, as AD cases are expected to be doubled by 2050. Recently, 5-HT4 receptors have been envisioned as target for alleviating AD associated cognitive impairment with potential disease modifying ability impacting disease progression. Usmarapride is a 5-HT4 receptor partial agonist, being developed for the possible treatment of AD with symptomatic and disease modifying potential. Usmarapride demonstrated promising effects in ameliorating cognitive deficits in diverse animal models of episodic, working, social, and emotional memories. Usmarapride produced elevation in cortical acetylcholine in rats. Furthermore, usmarapride increased levels of soluble amyloid precursor protein alpha, a potential mechanism to reverse toxic Aβ peptide pathology. Usmarapride also potentiated the pharmacological effects of donepezil in animal models. To conclude, usmarapride may be a promising intervention for alleviating the cognitive dysfunction in AD patients with disease modifying potential.
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Sourbron J, Lagae L. Serotonin receptors in epilepsy: novel treatment targets? Epilepsia Open 2022; 7:231-246. [PMID: 35075810 PMCID: PMC9159250 DOI: 10.1002/epi4.12580] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 01/08/2022] [Accepted: 01/20/2022] [Indexed: 11/24/2022] Open
Abstract
Despite the availability of over 30 antiseizure medications (ASMs), there is no “one size fits it all,” so there is a continuing search for novel ASMs. There are divergent data demonstrating that modulation of distinct serotonin (5‐hydroxytryptamine, 5‐HT) receptors subtypes could be beneficial in the treatment of epilepsy and its comorbidities, whereas only a few ASM, such as fenfluramine (FA), act via 5‐HT. There are 14 different 5‐HT receptor subtypes, and most epilepsy studies focus on one or a few of these subtypes, using different animal models and different ligands. We reviewed the available evidence of each 5‐HT receptor subtype using MEDLINE up to July 2021. Our search included medical subject heading (MeSH) and free terms of each “5‐HT subtype” separately and its relation to “epilepsy or seizures.” Most research underlines the antiseizure activity of 5‐HT1A,1D,2A,2C,3 agonism and 5‐HT6 antagonism. Consistently, FA, which has recently been approved for the treatment of seizures in Dravet syndrome, is an agonist of 5‐HT1D,2A,2C receptors. Even though each study focused on a distinct seizure/epilepsy type and generalization of different findings could lead to false interpretations, we believe that the available preclinical and clinical studies emphasize the role of serotonergic modulation, especially stimulation, as a promising avenue in epilepsy treatment.
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Affiliation(s)
- Jo Sourbron
- Department of Development and Regeneration, Section Pediatric Neurology, University Hospital KU Leuven, Leuven, Belgium.,Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium
| | - Lieven Lagae
- Department of Development and Regeneration, Section Pediatric Neurology, University Hospital KU Leuven, Leuven, Belgium
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Memory Disorders Related to Hippocampal Function: The Interest of 5-HT 4Rs Targeting. Int J Mol Sci 2021; 22:ijms222112082. [PMID: 34769511 PMCID: PMC8584667 DOI: 10.3390/ijms222112082] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 10/30/2021] [Accepted: 11/03/2021] [Indexed: 11/16/2022] Open
Abstract
The hippocampus has long been considered as a key structure for memory processes. Multilevel alterations of hippocampal function have been identified as a common denominator of memory impairments in a number of psychiatric and neurodegenerative diseases. For many years, the glutamatergic and cholinergic systems have been the main targets of therapeutic treatments against these symptoms. However, the high rate of drug development failures has left memory impairments on the sideline of current therapeutic strategies. This underscores the urgent need to focus on new therapeutic targets for memory disorders, such as type 4 serotonin receptors (5-HT4Rs). Ever since the discovery of their expression in the hippocampus, 5-HT4Rs have gained growing interest for potential use in the treatment of learning and memory impairments. To date, much of the researched information gathered by scientists from both animal models and humans converge on pro-mnesic and anti-amnesic properties of 5-HT4Rs activation, although the mechanisms at work require more work to be fully understood. This review addresses a fundamental, yet poorly understood set of evidence of the potential of 5-HT4Rs to re-establish or limit hippocampal alterations related to neurological diseases. Most importantly, the potential of 5-HT4Rs is translated by refining hypotheses regarding the benefits of their activation in memory disorders at the hippocampal level.
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Déjà-vu? Neural and behavioural effects of the 5-HT 4 receptor agonist, prucalopride, in a hippocampal-dependent memory task. Transl Psychiatry 2021; 11:497. [PMID: 34602607 PMCID: PMC8488034 DOI: 10.1038/s41398-021-01568-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 08/04/2021] [Accepted: 08/16/2021] [Indexed: 11/13/2022] Open
Abstract
Cognitive deficits commonly accompany psychiatric disorders but are often underrecognised, and difficult to treat. The 5-HT4 receptor is a promising potential treatment target for cognitive impairment because in animal studies 5-HT4 receptor agonists enhance hippocampal-dependent memory processes. To date, there has been little work translating these effects to humans. We tested whether short-term administration of the 5-HT4 partial agonist, prucalopride, modified behavioural and neural (fMRI) memory processing in 44 healthy human volunteers using an experimental medicine model. We found that participants who had received six days of prucalopride treatment were significantly better at recalling previously seen neutral images and distinguishing them from new images. At a neural level, prucalopride bilaterally increased hippocampal activity and activity in the right angular gyrus compared with placebo. Taken together, these findings demonstrate the potential of 5-HT4-receptor activation for cognitive enhancement in humans, and support the potential of this receptor as a treatment target for cognitive impairment.
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Murphy SE, de Cates AN, Gillespie AL, Godlewska BR, Scaife JC, Wright LC, Cowen PJ, Harmer CJ. Translating the promise of 5HT 4 receptor agonists for the treatment of depression. Psychol Med 2021; 51:1111-1120. [PMID: 32241310 PMCID: PMC8188527 DOI: 10.1017/s0033291720000604] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Revised: 02/21/2020] [Accepted: 02/28/2020] [Indexed: 12/11/2022]
Abstract
Animal experimental studies suggest that 5-HT4 receptor activation holds promise as a novel target for the treatment of depression and cognitive impairment. 5-HT4 receptors are post-synaptic receptors that are located in striatal and limbic areas known to be involved in cognition and mood. Consistent with this, 5-HT4 receptor agonists produce rapid antidepressant effects in a number of animal models of depression, and pro-cognitive effects in tasks of learning and memory. These effects are accompanied by molecular changes, such as the increased expression of neuroplasticity-related proteins that are typical of clinically useful antidepressant drugs. Intriguingly, these antidepressant-like effects have a fast onset of their action, raising the possibility that 5-HT4 receptor agonists may be a particularly useful augmentation strategy in the early stages of SSRI treatment. Until recently, the translation of these effects to humans has been challenging. Here, we review the evidence from animal studies that the 5-HT4 receptor is a promising target for the treatment of depression and cognitive disorders, and outline a potential pathway for the efficient and cost-effective translation of these effects into humans and, ultimately, to the clinic.
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Affiliation(s)
- Susannah E Murphy
- University Department of Psychiatry, Warneford Hospital, University of Oxford, OX3 7JX, UK
- Oxford Health NHS Foundation Trust, Warneford Hospital, Oxford, UK
| | - Angharad N de Cates
- University Department of Psychiatry, Warneford Hospital, University of Oxford, OX3 7JX, UK
- Oxford Health NHS Foundation Trust, Warneford Hospital, Oxford, UK
| | - Amy L Gillespie
- University Department of Psychiatry, Warneford Hospital, University of Oxford, OX3 7JX, UK
- Oxford Health NHS Foundation Trust, Warneford Hospital, Oxford, UK
| | - Beata R Godlewska
- University Department of Psychiatry, Warneford Hospital, University of Oxford, OX3 7JX, UK
- Oxford Health NHS Foundation Trust, Warneford Hospital, Oxford, UK
| | - Jessica C Scaife
- University Department of Psychiatry, Warneford Hospital, University of Oxford, OX3 7JX, UK
- Oxford Health NHS Foundation Trust, Warneford Hospital, Oxford, UK
| | - Lucy C Wright
- University Department of Psychiatry, Warneford Hospital, University of Oxford, OX3 7JX, UK
- Oxford Health NHS Foundation Trust, Warneford Hospital, Oxford, UK
| | - Philip J Cowen
- University Department of Psychiatry, Warneford Hospital, University of Oxford, OX3 7JX, UK
- Oxford Health NHS Foundation Trust, Warneford Hospital, Oxford, UK
| | - Catherine J Harmer
- University Department of Psychiatry, Warneford Hospital, University of Oxford, OX3 7JX, UK
- Oxford Health NHS Foundation Trust, Warneford Hospital, Oxford, UK
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7
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Lecouflet P, Roux CM, Potier B, Leger M, Brunet E, Billard JM, Schumann-Bard P, Freret T. Interplay between 5-HT4 Receptors and GABAergic System within CA1 Hippocampal Synaptic Plasticity. Cereb Cortex 2020; 31:694-701. [PMID: 32935845 DOI: 10.1093/cercor/bhaa253] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 07/31/2020] [Accepted: 08/13/2020] [Indexed: 12/18/2022] Open
Abstract
The type 4 serotonin receptor (5-HT4R) is highly involved in cognitive processes such as learning and memory. Behavioral studies have shown a beneficial effect of its activation and conversely reported memory impairments by its blockade. However, how modulation of 5HT4R enables modifications of hippocampal synaptic plasticity remains elusive. To shed light on the mechanisms at work, we investigated the effects of the 5-HT4R agonist RS67333 on long-term potentiation (LTP) within the hippocampal CA1 area. Although high-frequency stimulation-induced LTP remained unaffected by RS67333, the magnitude of LTP induced by theta-burst stimulation was significantly decreased. This effect was blocked by the selective 5-HT4R antagonist RS39604. Further, 5-HT4R-induced decrease in LTP magnitude was fully abolished in the presence of bicuculline, a GABAAR antagonist; hence, demonstrating involvement of GABA neurotransmission. In addition, we showed that the application of a GABABR antagonist, CGP55845, mimicked the effect of 5-HT4R activation, whereas concurrent application of CGP55845 and RS67333 did not elicit an additive inhibition effect on LTP. To conclude, through investigation of theta burst induced functional plasticity, we demonstrated an interplay between 5-HT4R activation and GABAergic neurotransmission within the hippocampal CA1 area.
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Affiliation(s)
- Pierre Lecouflet
- Normandie Univ, UNICAEN, INSERM, COMETE, GIP CYCERON, 14000 Caen, France
| | - Candice M Roux
- Normandie Univ, UNICAEN, INSERM, COMETE, GIP CYCERON, 14000 Caen, France.,PORSOLT, 53940 Le Genest Saint-Isle, France
| | - Brigitte Potier
- LUMIN, Univ Paris-Saclay, CNRS, ENS Paris-Saclay, 91190 Gif-sur-Yvette, France
| | - Marianne Leger
- Normandie Univ, UNICAEN, INSERM, COMETE, GIP CYCERON, 14000 Caen, France
| | - Elie Brunet
- Normandie Univ, UNICAEN, INSERM, COMETE, GIP CYCERON, 14000 Caen, France
| | - Jean-Marie Billard
- Normandie Univ, UNICAEN, INSERM, COMETE, GIP CYCERON, 14000 Caen, France
| | | | - Thomas Freret
- Normandie Univ, UNICAEN, INSERM, COMETE, GIP CYCERON, 14000 Caen, France
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8
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Bernstein HL, Lu YL, Botterill JJ, Scharfman HE. Novelty and Novel Objects Increase c-Fos Immunoreactivity in Mossy Cells in the Mouse Dentate Gyrus. Neural Plast 2019; 2019:1815371. [PMID: 31534449 PMCID: PMC6732597 DOI: 10.1155/2019/1815371] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 07/05/2019] [Indexed: 02/06/2023] Open
Abstract
The dentate gyrus (DG) and its primary cell type, the granule cell (GC), are thought to be critical to many cognitive functions. A major neuronal subtype of the DG is the hilar mossy cell (MC). MCs have been considered to play an important role in cognition, but in vivo studies to understand the activity of MCs during cognitive tasks are challenging because the experiments usually involve trauma to the overlying hippocampus or DG, which kills hilar neurons. In addition, restraint typically occurs, and MC activity is reduced by brief restraint stress. Social isolation often occurs and is potentially confounding. Therefore, we used c-fos protein expression to understand when MCs are active in vivo in socially housed adult C57BL/6 mice in their home cage. We focused on c-fos protein expression after animals explored novel objects, based on previous work which showed that MCs express c-fos protein readily in response to a novel housing location. Also, MCs are required for the training component of the novel object location task and novelty-encoding during a food-related task. GluR2/3 was used as a marker of MCs. The results showed that MC c-fos protein is greatly increased after exposure to novel objects, especially in ventral DG. We also found that novel objects produced higher c-fos levels than familiar objects. Interestingly, a small subset of neurons that did not express GluR2/3 also increased c-fos protein after novel object exposure. In contrast, GCs appeared relatively insensitive. The results support a growing appreciation of the role of the DG in novelty detection and novel object recognition, where hilar neurons and especially MCs are very sensitive.
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Affiliation(s)
- Hannah L. Bernstein
- The Nathan S. Kline Institute for Psychiatric Research, Center for Dementia Research, 140 Old Orangeburg Rd., Orangeburg, NY 10962, USA
- Departments of Child and Adolescent Psychiatry, Neuroscience and Physiology, and Psychiatry, and the Neuroscience Institute, New York University Langone Health, 100 First Ave., New York, NY 10016, USA
| | - Yi-Ling Lu
- The Nathan S. Kline Institute for Psychiatric Research, Center for Dementia Research, 140 Old Orangeburg Rd., Orangeburg, NY 10962, USA
- Departments of Child and Adolescent Psychiatry, Neuroscience and Physiology, and Psychiatry, and the Neuroscience Institute, New York University Langone Health, 100 First Ave., New York, NY 10016, USA
| | - Justin J. Botterill
- The Nathan S. Kline Institute for Psychiatric Research, Center for Dementia Research, 140 Old Orangeburg Rd., Orangeburg, NY 10962, USA
- Departments of Child and Adolescent Psychiatry, Neuroscience and Physiology, and Psychiatry, and the Neuroscience Institute, New York University Langone Health, 100 First Ave., New York, NY 10016, USA
| | - Helen E. Scharfman
- The Nathan S. Kline Institute for Psychiatric Research, Center for Dementia Research, 140 Old Orangeburg Rd., Orangeburg, NY 10962, USA
- Departments of Child and Adolescent Psychiatry, Neuroscience and Physiology, and Psychiatry, and the Neuroscience Institute, New York University Langone Health, 100 First Ave., New York, NY 10016, USA
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Ishida Y, Sugiura Y, Magome T, Kamakura T, Takimoto Y, Hanada Y, Kitayama K, Nakamura Y, Shimada S, Ohta N, Naono-Nakayama R, Kamijo K. Expression Analysis of Serotonin Receptors, Serotonin Transporter and l-Amino Acid Decarboxylase in the Mouse Sphenopalatine Ganglion by RT-PCR, Northern Blot Analysis and In Situ Hybridization. Neuroscience 2019; 411:23-36. [PMID: 31128160 DOI: 10.1016/j.neuroscience.2019.05.028] [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: 01/19/2019] [Revised: 05/03/2019] [Accepted: 05/14/2019] [Indexed: 11/26/2022]
Abstract
The sphenopalatine ganglion (SPG) is a gathering of the cell bodies of parasympathetic fibers that dominate the nasal gland, lacrimal gland and cerebral blood vessels. The SPG controls nasal secretions, tears, and the dilation of cerebral blood vessels. However, it is unclear how serotonin regulates SPG functions. In this study, we investigated the expression of genes involved in the serotonergic system in the mouse SPG. We examined the mRNA expression levels of 5-HT1A, 5-HT1B, 5-HT1D, 5-HT1F, 5-HT2A, 5-HT2B, 5-HT2C, 5-HT3A, 5-HT3B, 5-HT4, 5-HT5A, 5-HT5B, 5-HT6 and 5-HT7 receptors, as well as serotonin transporter, tryptophan hydroxylases 1 and 2, and L-amino acid decarboxylase (AADC) by RT-PCR. It revealed that the 5-HT3A and 5-HT3B ionotropic receptors and AADC were likely to be highly expressed in the SPG, as measured by RT-PCR. We next performed in situ hybridization on the SPG to examine the expression of these three genes at the cellular level after validating the specificity of each cRNA probe by northern blotting. The 5-HT3A receptor, 5-HT3B receptor, and AADC were expressed in 96.5% ± 1.0%, 29.7% ± 10.7%, and 57.4% ± 2.9% of neuronal cell bodies in the SPG, respectively, indicating that the 5-HT3A receptor was virtually expressed in all SPG neurons. Our results on the expression of these critical serotonin system genes in the parasympathetic SPG provide insight into the pathogenetics of rhinitis, conjunctivitis and headache. Furthermore, our findings suggest that targeting the 5-HT3A receptor might have therapeutic potential in the treatment of these ailments.
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Affiliation(s)
- Yusuke Ishida
- Division of Anatomy and Cell Biology, Tohoku Medical and Pharmaceutical University, 1-15-1 Fukumuro, Miyagino-ku, Sendai 983-8536, Japan; Department of Neuroscience and Cell Biology, Graduate School of Medicine, Osaka University, Osaka 565-0871, Japan; Division of Otorhinolaryngology, Tohoku Medical and Pharmaceutical University, 1-15-1 Fukumuro, Miyagino-ku, Sendai 983-8536, Japan.
| | - Yusuke Sugiura
- Department of Neuroscience and Cell Biology, Graduate School of Medicine, Osaka University, Osaka 565-0871, Japan
| | - Takuya Magome
- Department of medicine for Sports and Performing Arts, Graduate School of Medicine, Osaka University, Osaka 565-0871, Japan
| | - Takefumi Kamakura
- Department of Neuroscience and Cell Biology, Graduate School of Medicine, Osaka University, Osaka 565-0871, Japan; Department of Otorhinolaryngology-Head and Neck Surgery, Graduate School of Medicine, Osaka University, Osaka 565-0871, Japan
| | - Yasumitsu Takimoto
- Department of Neuroscience and Cell Biology, Graduate School of Medicine, Osaka University, Osaka 565-0871, Japan; Department of Otorhinolaryngology-Head and Neck Surgery, Graduate School of Medicine, Osaka University, Osaka 565-0871, Japan
| | - Yukiko Hanada
- Department of Neuroscience and Cell Biology, Graduate School of Medicine, Osaka University, Osaka 565-0871, Japan; Department of Otorhinolaryngology-Head and Neck Surgery, Graduate School of Medicine, Osaka University, Osaka 565-0871, Japan
| | - Kazuki Kitayama
- Department of Neuroscience and Cell Biology, Graduate School of Medicine, Osaka University, Osaka 565-0871, Japan
| | - Yukiko Nakamura
- Department of Neuroscience and Cell Biology, Graduate School of Medicine, Osaka University, Osaka 565-0871, Japan
| | - Shoichi Shimada
- Department of Neuroscience and Cell Biology, Graduate School of Medicine, Osaka University, Osaka 565-0871, Japan
| | - Nobuo Ohta
- Division of Otorhinolaryngology, Tohoku Medical and Pharmaceutical University, 1-15-1 Fukumuro, Miyagino-ku, Sendai 983-8536, Japan
| | - Rumi Naono-Nakayama
- Division of Anatomy and Cell Biology, Tohoku Medical and Pharmaceutical University, 1-15-1 Fukumuro, Miyagino-ku, Sendai 983-8536, Japan
| | - Keiju Kamijo
- Division of Anatomy and Cell Biology, Tohoku Medical and Pharmaceutical University, 1-15-1 Fukumuro, Miyagino-ku, Sendai 983-8536, Japan
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10
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Rebholz H, Friedman E, Castello J. Alterations of Expression of the Serotonin 5-HT4 Receptor in Brain Disorders. Int J Mol Sci 2018; 19:ijms19113581. [PMID: 30428567 PMCID: PMC6274737 DOI: 10.3390/ijms19113581] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2018] [Revised: 11/03/2018] [Accepted: 11/06/2018] [Indexed: 01/12/2023] Open
Abstract
The serotonin 4 receptor, 5-HT₄R, represents one of seven different serotonin receptor families and is implicated in a variety of physiological functions and their pathophysiological variants, such as mood and depression or anxiety, food intake and obesity or anorexia, or memory and memory loss in Alzheimer's disease. Its central nervous system expression pattern in the forebrain, in particular in caudate putamen, the hippocampus and to lesser extent in the cortex, predispose it for a role in executive function and reward-related actions. In rodents, regional overexpression or knockdown in the prefrontal cortex or the nucleus accumbens of 5-HT₄R was shown to impact mood and depression-like phenotypes, food intake and hypophagia; however, whether expression changes are causally involved in the etiology of such disorders is not clear. In this context, more data are emerging, especially based on PET technology and the use of ligand tracers that demonstrate altered 5-HT₄R expression in brain disorders in humans, confirming data stemming from post-mortem tissue and preclinical animal models. In this review, we would like to present the current knowledge of 5-HT₄R expression in brain regions relevant to mood/depression, reward and executive function with a focus on 5-HT₄R expression changes in brain disorders or caused by drug treatment, at both the transcript and protein levels.
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Affiliation(s)
- Heike Rebholz
- Department of Molecular, Cellular and Biomedical Sciences, CUNY School of Medicine, New York, NY 10031, USA.
| | - Eitan Friedman
- Department of Molecular, Cellular and Biomedical Sciences, CUNY School of Medicine, New York, NY 10031, USA.
- Ph.D. Programs in Biochemistry and Biology, The Graduate Center, City University of New York, New York, NY 10031, USA.
| | - Julia Castello
- Department of Molecular, Cellular and Biomedical Sciences, CUNY School of Medicine, New York, NY 10031, USA.
- Ph.D. Programs in Biochemistry and Biology, The Graduate Center, City University of New York, New York, NY 10031, USA.
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Popova E, Kupenova P. Interaction between the serotoninergic and GABAergic systems in frog retina as revealed by electroretinogram. Acta Neurobiol Exp (Wars) 2017. [DOI: 10.21307/ane-2017-067] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Hagena H, Manahan-Vaughan D. The serotonergic 5-HT4 receptor: A unique modulator of hippocampal synaptic information processing and cognition. Neurobiol Learn Mem 2016; 138:145-153. [PMID: 27317942 DOI: 10.1016/j.nlm.2016.06.014] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Revised: 06/06/2016] [Accepted: 06/14/2016] [Indexed: 01/10/2023]
Abstract
Serotonin (5-hydroxytryptamine, 5-HT) contributes in multifarious ways to the regulation of brain function, spanning key aspects such as the sleep-wake cycle, appetite, mood and mental health. The 5-HT receptors comprise seven receptor families (5-HT1-7) that are further subdivided into 14 receptor subtypes. The role of the 5-HT receptor in the modulation of neuronal excitability has been well documented. Recently, however, it has become apparent that the 5-HT4 receptor may contribute significantly to cognition and regulates less ostensible aspects of brain function: it engages in metaplastic regulation of synaptic responsiveness in key brain structures such as the hippocampus, thereby specifically promoting persistent forms of synaptic plasticity, and influences the direction of change in synaptic strength in selected hippocampal subfields. This highly specific neuromodulatory control by the 5-HT4 receptor may in turn explain the reported role for this receptor in hippocampus-dependent cognition. In this review article, we describe the role of the 5-HT4 receptor in hippocampal function, and describe how this receptor plays a unique and highly specialised role in synaptic information storage and cognition.
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Affiliation(s)
- Hardy Hagena
- Department of Neurophysiology, Medical Faculty, Ruhr University Bochum, Germany
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Nozaki K, Kubo R, Furukawa Y. Serotonin modulates the excitatory synaptic transmission in the dentate granule cells. J Neurophysiol 2016; 115:2997-3007. [PMID: 26961099 DOI: 10.1152/jn.00064.2016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Accepted: 03/04/2016] [Indexed: 01/23/2023] Open
Abstract
Serotonergic fibers from the raphe nuclei project to the hippocampal formation, the activity of which is known to modulate the inhibitory interneurons in the dentate gyrus. On the other hand, serotonergic modulation of the excitatory synapses in the dentate gyrus is not well examined. In the present study, we examined the effects of 5-HT on the excitatory postsynaptic potentials (EPSPs) in the dentate granule cells evoked by the selective stimulation of the lateral perforant path (LPP), the medial perforant path (MPP), or the mossy cell fibers (MCF). 5-HT depressed the amplitude of unitary EPSPs (uEPSPs) evoked by the stimulation of LPP or MPP, whereas uEPSPs evoked by MCF stimulation were little affected. The effect was partly explained by the decrease of the resting membrane resistance following the activation of 5-HT1A receptors, which was confirmed by computer simulations. We also found that the probability of evoking uEPSP by LPP stimulation but not MPP or MCF stimulation was reduced by 5-HT and that the paired-pulse ratio of LPP-evoked EPSP but not that of MPP- or MCF-evoked ones was increased by 5-HT. These effects were blocked by 5-HT2 antagonist, suggesting that the transmitter release in the LPP-granule cell synapse is inhibited by the activation of 5-HT2 receptors. The present results suggest that 5-HT can modulate the EPSPs in the dentate granule cells by at least two distinct mechanisms.
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Affiliation(s)
- Kanako Nozaki
- Laboratory of Neurobiology, Faculty of Integrated Arts and Sciences, Hiroshima University, Kagamiyama, Higashi-Hiroshima, Japan; and
| | - Reika Kubo
- Department of Neurophysiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Kasumi, Naka-ku, Hiroshima, Japan
| | - Yasuo Furukawa
- Laboratory of Neurobiology, Faculty of Integrated Arts and Sciences, Hiroshima University, Kagamiyama, Higashi-Hiroshima, Japan; and
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Twarkowski H, Hagena H, Manahan-Vaughan D. The 5-hydroxytryptamine4 receptor enables differentiation of informational content and encoding in the hippocampus. Hippocampus 2016; 26:875-91. [PMID: 26800645 PMCID: PMC5067691 DOI: 10.1002/hipo.22569] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Revised: 01/15/2016] [Accepted: 01/20/2016] [Indexed: 11/10/2022]
Abstract
Long‐term synaptic plasticity, represented by long‐term depression (LTD) and long‐term potentiation (LTP) comprise cellular processes that enable memory. Neuromodulators such as serotonin regulate hippocampal function, and the 5‐HT4‐receptor contributes to processes underlying cognition. It was previously shown that in the CA1‐region, 5‐HT4‐receptors regulate the frequency‐response relationship of synaptic plasticity: patterned afferent stimulation that has no effect on synaptic strength (i.e., a θm‐frequency), will result in LTP or LTD, when given in the presence of a 5‐HT4‐agonist, or antagonist, respectively. Here, we show that in the dentate gyrus (DG) and CA3 regions of freely behaving rats, pharmacological manipulations of 5‐HT4‐receptors do not influence responses generated at θm‐frequencies, but activation of 5‐HT4‐receptors prevents persistent LTD in mossy fiber (mf)‐CA3, or perforant path‐DG synapses. Furthermore, the regulation by 5‐HT4‐receptors of LTP is subfield‐specific: 5‐HT4‐receptor‐activation prevents mf‐CA3‐LTP, but does not strongly affect DG‐potentiation. These data suggest that 5‐HT4‐receptor activation prioritises information encoding by means of LTP in the DG and CA1 regions, and suppresses persistent information storage in mf‐CA3 synapses. Thus, 5‐HT4‐receptors serve to shape information storage across the hippocampal circuitry and specify the nature of experience‐dependent encoding. © 2016 The Authors Hippocampus Published by Wiley Periodicals, Inc.
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Affiliation(s)
- Hannah Twarkowski
- Department of Neurophysiology, Medical Faculty, Ruhr University Bochum, Bochum, Germany.,International Graduate School of Neuroscience, Ruhr University Bochum, Bochum, Germany
| | - Hardy Hagena
- Department of Neurophysiology, Medical Faculty, Ruhr University Bochum, Bochum, Germany
| | - Denise Manahan-Vaughan
- Department of Neurophysiology, Medical Faculty, Ruhr University Bochum, Bochum, Germany.,International Graduate School of Neuroscience, Ruhr University Bochum, Bochum, Germany
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15
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The role of different serotonin receptor subtypes in seizure susceptibility. Exp Brain Res 2013; 232:347-67. [PMID: 24232860 DOI: 10.1007/s00221-013-3757-0] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2013] [Accepted: 10/27/2013] [Indexed: 10/26/2022]
Abstract
5-Hydroxytryptamine (5-HT) has the most diverse set of receptors in comparison with any other neurotransmitter or hormone in the body. To date, seven families of 5-HT receptors have been characterized. A great number of studies have been published regarding the role of 5-HT and its receptors in seizures. However, with a few exceptions, the net effect of activating or inhibiting each 5-HT receptor subtype on the development or severity of seizures remains controversial. Additionally, the results of studies, which have used knockout animals to investigate the role of 5-HT receptors in seizures, have sometimes been contradictory to those which have used pharmacological tools. The present study aims to review the available data regarding the influence of each receptor subtype on seizure development and, when possible, reconcile between the apparently different results obtained in these studies.
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Zetterström TSC, Coppell AA, Khundakar AA. The role of 5-hydroxytryptamine receptor subtypes in the regulation of brain-derived neurotrophic factor gene expression. J Pharm Pharmacol 2013; 66:53-61. [DOI: 10.1111/jphp.12153] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Accepted: 09/05/2013] [Indexed: 11/30/2022]
Abstract
Abstract
Objectives
The study aims to investigate the role of 5-hydroxytryptamine receptor subtypes in mediating the inhibitory effect of the selective serotonin reuptake inhibitor (fluoxetine on brain-derived neurotrophic factor gene (bdnf) expression in rat hippocampus.
Methods
In situ hybridization was used for regional determination of bdnf expression levels in hippocampal brain slices from normal, lesioned (5-hydroxytryptamine or noradrenaline) or adrenalectomized rats; treated with fluoxetine and/or 5-hydroxytryptamine selective ligands.
Key findings
Our study shows that the transient fluoxetine-induced down-regulation of bdnf gene expression depends on an intact 5-hydroxytryptamine but not noradrenaline system or circulating glucocorticoids. Pretreatment with the 5-hydroxytryptamine4 antagonist SB-204070 blocked the overall fluoxetine-induced inhibition of bdnf levels in hippocampus, while pretreatment with the 5-hydroxytryptamine2 antagonists ketanserin had an effect in the CA3 but not in the dentate gyrus sub-region of hippocampus. The 5-hydroxytryptamine1A antagonist WAY-100635 and the 5-hydroxytryptamine3 antagonist granisetron were both ineffective.
Conclusions
Our study found strong support for a primary effect of 5-hydroxytryptamine but not noradrenaline or circulating glucocorticoids in the mediation of fluoxetine-induced down-regulation of bdnf expression. More specifically, we also show that 5-hydroxytryptamine4 receptor-stimulation seems to play a pivotal role in this effect.
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Affiliation(s)
- Tyra S C Zetterström
- Leicester School of Pharmacy, Faculty of Health and Life Sciences, De Montfort University, Leicester, UK
| | - Alexander A Coppell
- Leicester School of Pharmacy, Faculty of Health and Life Sciences, De Montfort University, Leicester, UK
| | - Ahmad A Khundakar
- Institute for Ageing and Health, Newcastle University, Campus For Ageing and Vitality, Newcastle, UK
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Duffy AM, Schaner MJ, Chin J, Scharfman HE. Expression of c-fos in hilar mossy cells of the dentate gyrus in vivo. Hippocampus 2013; 23:649-55. [PMID: 23640815 PMCID: PMC3732572 DOI: 10.1002/hipo.22138] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/17/2013] [Indexed: 01/15/2023]
Abstract
Granule cells (GCs) of the dentate gyrus (DG) are considered to be quiescent--they rarely fire action potentials. In contrast, the other glutamatergic cell type in the DG, hilar mossy cells (MCs) often have a high level of spontaneous activity based on recordings in hippocampal slices. MCs project to GCs, so activity in MCs could play an important role in activating GCs. Therefore, we investigated whether MCs were active under basal conditions in vivo, using the immediate early gene c-fos as a tool. We hypothesized that MCs would exhibit c-fos expression even if rats were examined randomly, under normal housing conditions. Therefore, adult male rats were perfused shortly after removal from their home cage and transfer to the laboratory. Remarkably, most c-fos immunoreactivity (ir) was in the hilus, especially temporal hippocampus. C-fos-ir hilar cells co-expressed GluR2/3, suggesting that they were MCs. C-fos-ir MCs were robust even when the animal was habituated to the investigator and laboratory where they were euthanized. However, c-fos-ir in dorsal MCs was reduced under these circumstances, suggesting that ventral and dorsal MCs are functionally distinct. Interestingly, there was an inverse relationship between MC and GC layer c-fos expression, with little c-fos expression in the GC layer in ventral sections where MC expression was strong, and the opposite in dorsal hippocampus. The results support the hypothesis that a subset of hilar MCs are spontaneously active in vivo and provide other DG neurons with tonic depolarizing input.
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Affiliation(s)
- Aine M. Duffy
- Center for Dementia Research, The Nathan Kline Institute for Psychiatric Research, Orangeburg, New York 10962
| | - Michael J. Schaner
- Center for Dementia Research, The Nathan Kline Institute for Psychiatric Research, Orangeburg, New York 10962
| | - Jeannie Chin
- Department of Neuroscience, Thomas Jefferson University, Philadelphia, PA 19107
| | - Helen E. Scharfman
- Center for Dementia Research, The Nathan Kline Institute for Psychiatric Research, Orangeburg, New York 10962
- Department of Child & Adolescent Psychiatry, Psychiatry, Physiology & Neuroscience, New York University Langone, Medical Center, New York, NY 10016
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Tokarski K, Bobula B, Grzegorzewska-Hiczwa M, Kusek M, Hess G. Stress- and antidepressant treatment-induced modifications of 5-HT₇ receptor functions in the rat brain. Pharmacol Rep 2013; 64:1305-15. [PMID: 23406741 DOI: 10.1016/s1734-1140(12)70928-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Revised: 10/24/2012] [Indexed: 01/07/2023]
Abstract
This paper summarizes a series of electrophysiological studies aimed at finding the effects of the activation of 5-HT(7) receptors on neuronal excitability as well as on excitatory and inhibitory synaptic transmission in the hippocampus and in the frontal cortex of the rat. These studies demonstrated that 5-HT(7) receptors play an important role in the modulation of the activity of the hippocampal network by regulating the excitability of pyramidal cells of the CA1 area, as well as via their effect on GABA and glutamatergic transmission. The reactivity of 5-HT(7) receptors in the hippocampus is decreased by repeated administration of antidepressant drugs and increased by a prolonged high level of corticosterone. More importantly, administration of antidepressant drug, imipramine, prevents the occurrence of corticosterone-induced changes in the function of hippocampal 5-HT(7) receptors. It has also been found that the blockade of 5-HT(7) receptors by the selective antagonist SB 269970, lasting for a few days, causes similar changes to those observed after long-term administration of antidepressants. Thus, it seems that the pharmacological blockade of 5-HT(7) receptors produces faster effects compared to classic antidepressant drugs. A similarity between the changes in the glutamatergic transmission induced by the blockade of 5 HT7 receptors and those caused by repeated administration of the antidepressant drug, imipramine, has also been found in the frontal cortex. It has also been shown that the changes in glutamatergic transmission and the impairment of long-term synaptic plasticity in the frontal cortex of animals subjected to repeated restraint stress are reversed by the blockade of 5-HT(7) receptors. Overall, these studies, together with the data provided by other investigators, support the hypothesis that 5-HT(7) receptor antagonists may become a prototype of a new class of antidepressant drugs. Such compounds will not function by blocking 5-HT reuptake, as many of the currently used drugs, but through a direct interaction with the 5-HT(7) receptor. This type of action is highly selective and usually does not require the occurrence of adaptive changes in neuronal functions, thus allowing for a much quicker therapeutic effect.
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Affiliation(s)
- Krzysztof Tokarski
- Department of Physiology, Institute of Pharmacology, Polish Academy of Sciences, Smętna 12, PL 31-343 Kraków, Poland.
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Effects of GABAB ligands alone and in combination with paroxetine on hippocampal BDNF gene expression. Eur J Pharmacol 2011; 671:33-8. [DOI: 10.1016/j.ejphar.2011.09.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2011] [Revised: 07/20/2011] [Accepted: 09/02/2011] [Indexed: 01/07/2023]
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20
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Segu L, Lecomte MJ, Wolff M, Santamaria J, Hen R, Dumuis A, Berrard S, Bockaert J, Buhot MC, Compan V. Hyperfunction of muscarinic receptor maintains long-term memory in 5-HT4 receptor knock-out mice. PLoS One 2010; 5:e9529. [PMID: 20209108 PMCID: PMC2832007 DOI: 10.1371/journal.pone.0009529] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2010] [Accepted: 02/11/2010] [Indexed: 11/18/2022] Open
Abstract
Patients suffering from dementia of Alzheimer's type express less serotonin 4 receptors (5-HTR4), but whether an absence of these receptors modifies learning and memory is unexplored. In the spatial version of the Morris water maze, we show that 5-HTR4 knock-out (KO) and wild-type (WT) mice performed similarly for spatial learning, short- and long-term retention. Since 5-HTR4 control mnesic abilities, we tested whether cholinergic system had circumvented the absence of 5-HTR4. Inactivating muscarinic receptor with scopolamine, at an ineffective dose (0.8 mg/kg) to alter memory in WT mice, decreased long-term but not short-term memory of 5-HTR4 KO mice. Other changes included decreases in the activity of choline acetyltransferase (ChAT), the required enzyme for acetylcholine synthesis, in the septum and the dorsal hippocampus in 5-HTR4 KO under baseline conditions. Training- and scopolamine-induced increase and decrease, respectively in ChAT activity in the septum in WT mice were not detected in the 5-HTR4 KO animals. Findings suggest that adaptive changes in cholinergic systems may circumvent the absence of 5-HTR4 to maintain long-term memory under baseline conditions. In contrast, despite adaptive mechanisms, the absence of 5-HTR4 aggravates scopolamine-induced memory impairments. The mechanisms whereby 5-HTR4 mediate a tonic influence on ChAT activity and muscarinic receptors remain to be determined.
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Affiliation(s)
- Luis Segu
- Centre de Neurosciences Intégratives et Cognitives, CNRS UMR5228, Bordeaux University, Talence, France
| | - Marie-José Lecomte
- Centre de Recherche de l'Institut du Cerveau et de la Moelle Epinière, CNRS UMR7225 INSERM UMR S975, Paris, France
| | - Mathieu Wolff
- Centre de Neurosciences Intégratives et Cognitives, CNRS UMR5228, Bordeaux University, Talence, France
| | - Julie Santamaria
- Centre de Recherche de l'Institut du Cerveau et de la Moelle Epinière, CNRS UMR7225 INSERM UMR S975, Paris, France
| | - René Hen
- Center for Neurobiology and Behavior, Columbia University, New York, New York, United States of America
| | - Aline Dumuis
- Institut de Génomique Fonctionnelle, Neurobiology, CNRS UMR5203 INSERM U661 Montpellier I & II University, Nîmes University, Montpellier, France
| | - Sylvie Berrard
- Centre de Recherche de l'Institut du Cerveau et de la Moelle Epinière, CNRS UMR7225 INSERM UMR S975, Paris, France
| | - Joël Bockaert
- Institut de Génomique Fonctionnelle, Neurobiology, CNRS UMR5203 INSERM U661 Montpellier I & II University, Nîmes University, Montpellier, France
| | - Marie-Christine Buhot
- Centre de Neurosciences Intégratives et Cognitives, CNRS UMR5228, Bordeaux University, Talence, France
| | - Valérie Compan
- Institut de Génomique Fonctionnelle, Neurobiology, CNRS UMR5203 INSERM U661 Montpellier I & II University, Nîmes University, Montpellier, France
- * E-mail:
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Lee JJ, Hahm ET, Lee CH, Cho YW. Serotonergic modulation of GABAergic and glutamatergic synaptic transmission in mechanically isolated rat medial preoptic area neurons. Neuropsychopharmacology 2008; 33:340-52. [PMID: 17392733 DOI: 10.1038/sj.npp.1301396] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The medial preoptic area (MPOA) of the hypothalamus is critically involved in the regulation of male sexual behavior and has been implicated in several homeostatic processes. Serotonin (5-hydroxytryptamine, 5-HT) inhibits sexual behavior via effects in the MPOA, where there are high densities of 5-HT(1A) and 5-HT(1B) receptor subtypes. We used whole-cell recordings under voltage-clamp conditions to investigate the serotonergic modulation of gamma-aminobutyric acid (GABA)ergic and glutamatergic synaptic transmission in mechanically dissociated rat MPOA neurons with native presynaptic nerve endings. Spontaneous GABAergic miniature inhibitory postsynaptic currents (mIPSCs) in the MPOA were completely blocked by bicuculline. Serotonin reversibly reduced the GABAergic mIPSC frequency without affecting the mean current amplitude. Serotonergic inhibition of mIPSC frequency was mimicked by (+/-)-8-hydroxy-2-dipropylaminotetralin hydrobromide, a specific 5-HT(1A) receptor agonist, and blocked by 1-(2-methoxyphenyl)-4-[4-(2-phthalimido)butyl] piperazine hydrobromide, a specific 5-HT(1A) receptor antagonist. 6-Cyano-7-nitroquinoxaline-2,3-dione completely blocked spontaneous glutamatergic miniature excitatory postsynaptic currents (mEPSCs) in the MPOA. Serotonin reversibly decreased the glutamatergic mEPSC frequency without affecting the mean current amplitude. Serotonergic inhibition of mEPSC frequency was mimicked by CGS 12066B, a specific 5-HT(1B) receptor agonist, and blocked by SB 216641, a specific 5-HT(1B) receptor antagonist. Stimulation of adenylyl cyclase with forskolin increased the frequencies of GABAergic mIPSCs and glutamatergic mEPSCs, and blocked the inhibitory effects of 5-HT. H-89, a selective protein kinase A (PKA) inhibitor, decreased the frequencies of GABAergic mIPSCs and glutamatergic mEPSCs, and blocked their reduction by 5-HT. These findings suggest that 5-HT reduces the frequency of GABAergic mIPSCs and glutamatergic mEPSCs through 5-HT(1A) and 5-HT(1B) receptor-mediated inhibition, respectively, of the PKA-dependent pathway in the presynaptic nerve terminals of MPOA neurons.
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Affiliation(s)
- Jong-Ju Lee
- Department of Physiology, College of Medicine, Kyung Hee University, Seoul, South Korea
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22
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Kornum BR, Weikop P, Moller A, Ronn LCB, Knudsen GM, Aznar S. Serotonin depletion results in a decrease of the neuronal activation caused by rivastigmine in the rat hippocampus. Brain Res 2006; 1073-1074:262-8. [PMID: 16426583 DOI: 10.1016/j.brainres.2005.12.030] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2005] [Revised: 12/09/2005] [Accepted: 12/09/2005] [Indexed: 10/25/2022]
Abstract
Interactions between the serotonergic and cholinergic systems are known to occur and are believed to play a role in the mechanism underlying both major depression and Alzheimer's disease. On a molecular level, studies suggest that acetylcholine (ACh) increases serotonin (5-HT) release through nicotinic receptors located at nerve terminals. The aim of the present study was to determine in which areas and to what extent 5-HT mediates the neuronal response to ACh release. For this purpose, neuronal activity was measured in rats with rivastigmine-induced elevated ACh levels after a 95% 5-HT depletion obtained by dosing p-chlorophenylalanine followed by D,L-fenfluramine. Neuronal activation was quantified by stereological measurements of c-Fos immunoreactivity. The brain areas examined were medial prefrontal cortex, septum, dorsal hippocampus, and dorsal raphe nucleus. Rivastigmine significantly increased c-Fos immunoreactivity in medial prefrontal cortex and the hippocampus, but not in the septum and dorsal raphe nucleus. 5-HT depletion decreased ACh-induced c-Fos immunoreactivity in the dentate gyrus. By contrast, 5-HT depletion had no effect on the ACh-induced activity in the other brain areas examined. It is concluded that 5-HT mediates part of the ACh-induced hippocampal neuronal activation, possibly mediated via locally released 5-HT.
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Affiliation(s)
- Birgitte R Kornum
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, Blegdamsvej 9, DK-2100 Copenhagen, Denmark.
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24
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Compan V, Zhou M, Grailhe R, Gazzara RA, Martin R, Gingrich J, Dumuis A, Brunner D, Bockaert J, Hen R. Attenuated response to stress and novelty and hypersensitivity to seizures in 5-HT4 receptor knock-out mice. J Neurosci 2004; 24:412-9. [PMID: 14724239 PMCID: PMC6729986 DOI: 10.1523/jneurosci.2806-03.2004] [Citation(s) in RCA: 140] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2003] [Revised: 10/27/2003] [Accepted: 10/27/2003] [Indexed: 11/21/2022] Open
Abstract
To study the functions of 5-HT4 receptors, a null mutation was engineered in the corresponding gene. 5-HT4 receptor knock-out mice displayed normal feeding and motor behaviors in baseline conditions but abnormal feeding and locomotor behavior in response to stress and novelty. Specifically, stress-induced hypophagia and novelty-induced exploratory activity were attenuated in the knock-out mice. In addition, pentylenetetrazol-induced convulsive responses were enhanced in the knock-out mice, suggesting an increase in neuronal network excitability. These results provide the first example of a genetic deficit that disrupts the ability of stress to reduce feeding and body weight and suggest that 5-HT4 receptors may be involved in stress-induced anorexia and seizure susceptibility.
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Affiliation(s)
- Valérie Compan
- Unité Propre de Recherche Centre National de la Recherche Scientifique 2580, Génomique fonctionnelle, Montpellier 34094, France.
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Tokarski K, Zahorodna A, Bobula B, Hess G. 5-HT7 receptors increase the excitability of rat hippocampal CA1 pyramidal neurons. Brain Res 2003; 993:230-4. [PMID: 14642852 DOI: 10.1016/j.brainres.2003.09.015] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In the CA1 area of rat hippocampal slices, a combined application of 5-CT, a potent 5-HT(1A) and 5-HT(7) receptor agonist, and WAY 100635, a selective 5-HT(1A) receptor antagonist, resulted in a reversible increase of the CA1 extracellular population spike amplitude. In whole-cell recording from identified pyramidal neurons, the effects of 5-CT applied in the presence of WAY 100635 involved a reduction of the slow afterhyperpolarization (sAHP) and the frequency adaptation of action potential firing, which could be blocked by a specific 5-HT(7) receptor antagonist SB 269970. The results indicate that the activation of 5-HT(7) receptors increases the excitability of hippocampal CA1 pyramidal cells.
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Affiliation(s)
- Krzysztof Tokarski
- Department of Physiology, Institute of Pharmacology, Polish Academy of Sciences, Smetna 12, 31-343, Krakow, Poland
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Bianchi C, Rodi D, Marino S, Beani L, Siniscalchi A. Dual effects of 5-HT4 receptor activation on GABA release from guinea pig hippocampal slices. Neuroreport 2002; 13:2177-80. [PMID: 12488792 DOI: 10.1097/00001756-200212030-00003] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The effects of BIMU-8, a 5-HT4 receptor agonist, were studied on GABA release in guinea pig hippocampal slices. BIMU-8 did not modify GABA outflow at rest but did display a complex action in electrically stimulated slices: at low concentrations it increased, and at higher concentrations inhibited, GABA release. These responses were competitively counteracted by GR 125487, a selective 5-HT4 receptor antagonist. The dual effects of BIMU-8 are consistent with its indirect cholinergic action since the M1 and M3 antagonist, 4-DAMP, prevented BIMU-8-elicited GABA facilitation, whereas the M2 antagonist AFDX-116 cancelled GABA inhibition. These results provide evidence that serotonin exerts a complex modulation on the GABAergic system, via 5-HT4 receptors, and suggest that the amine releases acetylcholine which, in turn, bidirectionally modulates GABA release.
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Affiliation(s)
- Clementina Bianchi
- Department of Clinical and Experimental Medicine: Section of Pharmacology, University of Ferrara, Via Fossato di Mortara 17-19, 44100 Ferrara, Italy.
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27
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Möck M, Schwarz C, Thier P. Serotonergic control of cerebellar mossy fiber activity by modulation of signal transfer by rat pontine nuclei neurons. J Neurophysiol 2002; 88:549-64. [PMID: 12163509 DOI: 10.1152/jn.2002.88.2.549] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Serotonergic modulation of precerebellar nuclei may be crucial for the function of the entire cerebellar system. To study the effects of serotonin (5-HT) on neurons located within the pontine nuclei (PN), the main source of cerebellar mossy fibers, we performed standard intracellular recordings from PN neurons in a slice preparation of the rat pontine brain stem. Application of 5 microM 5-HT significantly altered several intrinsic membrane properties of PN neurons. First, it depolarized the somatic membrane potential by 6.5 +/- 3.5 mV and increased the apparent input resistance from 49.5 +/- 14.6 to 62.7 +/- 21.1 MOmega. Second, 5-HT altered the I-V relationship of PN neurons: it decreased the inward rectification in hyperpolarizing direction, but increased it when depolarizing currents were applied. Third, it decreased the rheobase from 0.32 +/- 0.14 to 0.24 +/- 0.14 nA without affecting the firing threshold. Finally, the amplitude of medium-duration after hyperpolarizations was reduced from -14.9 +/- 2.0 to -12.3 +/- 2.4 mV. Together, these 5-HT effects on the intrinsic membrane properties result in an increase in excitability and instantaneous firing rate. In addition, application of 5 microM 5-HT also modulated postsynaptic potentials (PSPs) evoked by electric stimulations within the cerebral peduncle. The amplitude, maximal slope, and integral of these PSPs were reduced to 46.2 +/- 23.4%, 45.7 +/- 23.7%, and 61.4 +/- 28.4% of the control value, respectively. In contrast, we found no change in the decay and voltage dependence of PSPs. To test modulatory effects on short-term synaptic facilitation, we applied pairs of electrical stimuli at intervals between 10 and 1,000 ms. 5-HT selectively enhanced the paired-pulse facilitation for interstimulus-intervals >20 ms. The alteration of paired-pulse facilitation points to a presynaptic site of action for 5-HT effects on synaptic transmission. Pharmacological experiments suggested that pre- and postsynaptic effects of 5-HT were mediated by two different kinds of 5-HT receptors: changes in intrinsic membrane properties were blocked by the 5-HT(2) receptor antagonist cinanserin while the reduction of PSPs was prevented by the 5-HT(1) receptor antagonist cyanopindolol. In conclusion, 5-HT increases the excitability of PN neurons but decreases the synaptic transmission on them. The selective enhancement of synaptic facilitation may, however, allow high-frequency inputs to effectively drive PN neurons, thus the PN may act as a high-pass filter during periods of 5-HT release.
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Affiliation(s)
- Martin Möck
- Abteilung Kognitive Neurologie, Neurologische Universitätsklinik Tübingen, Auf der Morgenstelle 15, Germany.
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Kulla A, Manahan-Vaughan D. Modulation by serotonin 5-HT(4) receptors of long-term potentiation and depotentiation in the dentate gyrus of freely moving rats. Cereb Cortex 2002; 12:150-62. [PMID: 11739263 DOI: 10.1093/cercor/12.2.150] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Tetanization-induced long-term potentiation (LTP) in the hippocampus can be depotentiated by low-frequency stimulation. 5-HT(4) receptors are expressed in the hippocampus and are suggested to be involved in hippocampus-dependent cognitive processes. Since the role of these receptors in the dentate gyrus has yet not been characterized, this study investigated the effects of 5-HT(4) receptors on basal synaptic transmission, LTP and depotentiation in the dentate gyrus of freely moving rats. Male Wistar rats were chronically implanted with a recording electrode in the dentate gyrus granule cell layer, a stimulation electrode in the medial perforant path and a cannula for drug administration in the ipsilateral ventricle. The 5-HT(4) agonist methoxytryptamine dose-dependently inhibited basal synaptic transmission and LTP. Priming of receptors by a dose of this agonist which elicited no significant change of basal synaptic transmission inhibited depotentiation. These effects could be prevented by the 5-HT(4) antagonist RS 39604, which did not produce independent effects on synaptic transmission, LTP or depotentiation. The effects of methoxytryptamine were confirmed with the highly selective 5-HT(4) agonist, RS 67333. These results strongly support a role for 5-HT(4) receptors in hippocampal synaptic plasticity and provide an important link to findings with regard to the involvement of 5-HT in processes related to learning and memory.
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Affiliation(s)
- Alexander Kulla
- Institute for Physiology of the Charite, Synaptic Plasticity Group, Humboldt University, Tucholskystrasse 2, D-10117 Berlin, Germany
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Licata F, Li Volsi G, Di Mauro M, Fretto G, Ciranna L, Santangelo F. Serotonin modifies the neuronal inhibitory responses to gamma-aminobutyric acid in the red nucleus: a microiontophoretic study in the rat. Exp Neurol 2001; 167:95-107. [PMID: 11161597 DOI: 10.1006/exnr.2001.7533] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The effects of 5-hydroxytryptamine (5-HT) on the inhibitory responses evoked by gamma-aminobutyric acid (GABA) in neurons of the red nucleus (RN) were studied using a microiontophoretic technique. Extracellular unitary recordings performed in anesthetized rats demonstrated that 5-HT ejection influenced GABA-evoked inhibition in 94% of RN neurons, enhancing them in 52% and depressing them in 46% of cases. Both effects were specific and dose-dependent,although enhancements or depressions of the GABA responses were respectively inversely and directly related to the doses of 5-HT applied. The type of modulation exerted by 5-HT on the GABA responses was independent of the action of the amine on background firing. In fact, 5-HT induced an enhancement of the GABA responses in neurons mostly located in the rostral RN and a depression in those in the caudal RN. The application of 8-hydroxy-2(di-n-propylamino)tetralin, a specific 5-HT(1A) receptor agonist, enhanced GABA responses, whereas alpha-methyl-5-hydroxytryptamine, a 5-HT(2A) receptor agonist, depressed them. Both the 5-HT(2) antagonist methysergide and the 5-HT(2A) selective antagonist ketanserin were able to block partially or totally the depressive action of 5-HT on GABA responses. In contrast, the same 5-HT antagonists mimicked the enhancing action of 5-HT on the GABA responses or were ineffective. Application of bicuculline, a GABA(A) receptor antagonist, enhanced the excitatory action of 5-HT on the background firing and slightly reduced the inhibitory action. It is concluded that 5-HT is able to modulate GABA-evoked responses in RN neurons by acting on both 5-HT(1A) and 5-HT(2A) receptors. The functional significance of a serotonergic control on GABAergic inhibitory effects in RN is discussed.
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Affiliation(s)
- F Licata
- Department of Physiological Sciences, University of Catania, Catania, 95125, Italy
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Mayeux-Portas V, File SE, Stewart CL, Morris RJ. Mice lacking the cell adhesion molecule Thy-1 fail to use socially transmitted cues to direct their choice of food. Curr Biol 2000; 10:68-75. [PMID: 10662668 DOI: 10.1016/s0960-9822(99)00278-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
BACKGROUND Thy-1 is a major cell-surface glycoprotein of mature neurons and certain other cells, including those of the lymphoreticular system. Despite being the simplest member of the immunoglobulin superfamily, the biological role of Thy-1 has proved elusive. Analysis of Thy-1 null mice has shown the presence of excessive GABAergic inhibition of neurotransmission in the dentate gyrus of the hippocampal formation selectively, without any neurological or behavioural effects being apparent. RESULTS We show here that Thy-1 null mice are unable to make the appropriate dietary choice in the test for social transmission of food preference, despite showing a normal level of social interaction with the demonstrator mouse, normal neophobia, and normal learning in a T-maze using scented food as cues. The mice also performed normally in tests of anxiety, locomotor activity, exploration of a novel environment, habituation to novelty and spatial learning. This phenotype is maintained on two different strain backgrounds, is rescued by transgenic expression of Thy-1 and by administration of the GABA(A) receptor antagonist pentylenetetrazole. CONCLUSIONS The test for social transmission of food preference is based on the normal ability of mice in a colony to learn from each other which foods are safe to eat. The lack of this key survival behaviour in Thy-1 null mice could act as an evolutionary pressure point to conserve expression of Thy-1. Furthermore, the specific cognitive defect caused by inactivation of the Thy-1 gene suggests that it would be worthwhile to determine the role of Thy-1 in certain human familial forms of mental retardation that map to chromosome 11q22-23 in the region of the Thy-1 locus rather than the nearby ataxia telangiectasia locus.
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Affiliation(s)
- V Mayeux-Portas
- Molecular Neurobiology Group, Laboratoire Physiopathologie Neuromusculaire, GKT Medical School, EPI 99-30, Institut de Biologie, London, Montpellier, SE1 1UL, 34060, UK, France
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Zahorodna A, Bijak M. An antidepressant-induced decrease in the responsiveness of hippocampal neurons to group I metabotropic glutamate receptor activation. Eur J Pharmacol 1999; 386:173-9. [PMID: 10618467 DOI: 10.1016/s0014-2999(99)00757-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Imipramine, a serotonin and noradrenaline uptake inhibitor, is the prototypical tricyclic antidepressant. The effects of imipramine on neuronal responsiveness to the group I glutamate metabotropic (mGlu) receptor agonist (RS)-3,5-dihydroxyphenylglycine (DHPG) were studied ex vivo, in the CA1 area of rat hippocampus, using extracellular and intracellular recording. DHPG increased the population spike amplitude, depolarized CA1 cells and decreased the slow afterhyperpolarization. Imipramine (20 microM) administered acutely in vitro did not change the effect of DHPG on population spikes. Repeated treatment with imipramine (10 mg/kg, twice daily, for 14 days) significantly attenuated the enhancing effect of DHPG (2.5 and 5 microM) on population spikes, as well as the DHPG-induced depolarization and the decrease in the slow afterhyperpolarization. Repeated treatment with imipramine had no effect on passive or active membrane properties of CA1 pyramidal cells. The results of the time-course experiment demonstrated that the imipramine-induced decrease in the responsiveness of CA1 cells to DHPG was apparent after a 7-day treatment; there was a further decrease after 14 days of treatment to a level which was not changed by longer (21-day) administration of imipramine. The attenuation of neuronal responsiveness to DHPG induced by a 14-day treatment was still detectable 7 days after imipramine withdrawal. It is concluded that repeated treatment with imipramine induces a decrease in the responsiveness of rat CA1 hippocampal neurons to group I mGlu receptor activation with a time course which correlates with the delayed onset of the therapeutic effect of antidepressants in humans. This suggests that alterations in mGlu receptors may contribute to antidepressant efficacy.
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Affiliation(s)
- A Zahorodna
- Department of Physiology, Institute of Pharmacology, Polish Academy of Sciences, Smetna 12, 31-343, Cracow, Poland
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Koyama S, Kubo C, Rhee JS, Akaike N. Presynaptic serotonergic inhibition of GABAergic synaptic transmission in mechanically dissociated rat basolateral amygdala neurons. J Physiol 1999; 518 ( Pt 2):525-38. [PMID: 10381597 PMCID: PMC2269437 DOI: 10.1111/j.1469-7793.1999.0525p.x] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
1. The basolateral amygdala (ABL) nuclei contribute to the process of anxiety. GABAergic transmission is critical in these nuclei and serotonergic inputs from dorsal raphe nuclei also significantly regulate GABA release. In mechanically dissociated rat ABL neurons, spontaneous miniature inhibitory postsynaptic currents (mIPSCs) arising from attached GABAergic presynaptic nerve terminals were recorded with the nystatin-perforated patch method and pharmacological isolation. 2. 5-HT reversibly reduced the GABAergic mIPSC frequency without affecting the mean amplitude. The serotonergic effect was mimicked by the 5-HT1A specific agonist 8-OH DPAT (8-hydroxy-2-(di-n-propylamino)tetralin) and blocked by the 5-HT1A antagonist spiperone. 3. The GTP-binding protein inhibitor N-ethylmaleimide removed the serotonergic inhibition of mIPSC frequency. In either K+-free or Ca2+-free external solution, 5-HT could inhibit mIPSC frequency. 4. High K+ stimulation increased mIPSC frequency and 8-OH DPAT inhibited this increase even in the presence of Cd2+. 5. Forskolin, an activator of adenylyl cyclase (AC), significantly increased synaptic GABA release frequency. Pretreatment with forskolin prevented the serotonergic inhibition of mIPSC frequency in both the standard and high K+ external solution. 6. Ruthenium Red (RR), an agent facilitating the secretory process in a Ca2+-independent manner, increased synaptic GABA release. 5-HT also suppressed RR-facilitated mIPSC frequency. 7. We conclude that 5-HT inhibits GABAergic mIPSCs by inactivating the AC-cAMP signal transduction pathway via a G-protein-coupled 5-HT1A receptor and this intracellular pathway directly acts on the GABA-releasing process independent of K+ and Ca2+ channels in the presynaptic nerve terminals.
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Affiliation(s)
- S Koyama
- Department of Physiology and Department of Psychosomatic Medicine, Faculty of Medicine, Kyushu University, Fukuoka, Japan
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Gulyás AI, Acsády L, Freund TF. Structural basis of the cholinergic and serotonergic modulation of GABAergic neurons in the hippocampus. Neurochem Int 1999; 34:359-72. [PMID: 10397363 DOI: 10.1016/s0197-0186(99)00041-8] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Ascending subcortical pathways effectively modulate hippocampal information processing. Two components, the cholinergic and serotonergic pathways have been demonstrated to play an important role in the generation of behaviour-dependent hippocampal EEG patterns. Several findings suggest that the above projections influence the activity of hippocampal interneurons. Here we review the available data from physiological, pharmacological and receptor localization experiments, drawing attention to the crucial role of interneurons in the transfer and amplification of subcortical effects on cortical information processing. We hypothesize that, by exerting diverse actions on different subsets of interneurons, the cholinergic and serotonergic systems might change the balance of somatic and dendritic inhibition, and consequently change the integrative properties of hippocampal principal cells.
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Affiliation(s)
- A I Gulyás
- Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest
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Vizi ES, Kiss JP. Neurochemistry and pharmacology of the major hippocampal transmitter systems: synaptic and nonsynaptic interactions. Hippocampus 1999; 8:566-607. [PMID: 9882017 DOI: 10.1002/(sici)1098-1063(1998)8:6<566::aid-hipo2>3.0.co;2-w] [Citation(s) in RCA: 278] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Hippocampus plays a crucial role in important brain functions (e.g. memory, learning) thus in the past two decades this brain region became a major objective of neuroscience research. During this period large number of anatomical, neurochemical and electrophysiological data have been accumulated. While excellent reviews have been published on the anatomy and electrophysiology of hippocampal formation, the neurochemistry of this area has not been thoroughly surveyed. Therefore the aim of this review is to summarize the neurochemical and pharmacological data on the release of the major neurotransmitters found in the hippocampal region: glutamate (GLU), gamma-amino butyric acid (GABA), acetylcholine (ACh), noradrenaline (NA) and serotonin (5-HT). In addition, this review analyzes the synaptic and nonsynaptic interactions between hippocampal neuronal elements and overviews how auto- and heteroreceptors are involved in the presynaptic modulation of transmitter release. The presented data clearly show that transmitters released from axon terminals without synaptic contact play an important role in the fine tuning of communication between neurons within a neuronal circuit.
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Affiliation(s)
- E S Vizi
- Department of Pharmacology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest.
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Schmitz D, Gloveli T, Empson RM, Heinemann U. Serotonin reduces polysynaptic inhibition via 5-HT1A receptors in the superficial entorhinal cortex. J Neurophysiol 1998; 80:1116-21. [PMID: 9744926 DOI: 10.1152/jn.1998.80.3.1116] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The superficial cells of the entorhinal cortex (EC), main input to the hippocampus, receive a serotonergic input from the raphe nuclei and express 5-hydroxytryptamine creatine sulfate complex (5-HT) receptors at high density. With the use of intracellular recordings, we investigated the effects of serotonin on synaptic inhibition of layer II and III neurons of the EC. Serotonin reduced both polysynaptic fast and slow inhibitory postsynaptic potentials (IPSPs) in projection neurons of the superficial EC. Polysynaptic fast and slow IPSPs were depressed by serotonin in a dose-dependent manner (0.1-100 microM). Serotonin in a concentration of 1 microM reduced the amplitudes of polysynaptic fast and slow IPSPs by approximately 40 and 50%, respectively. To identify the subtype of the 5-HT-receptor mediating the effects on polysynaptic IPSPs, we applied various 5-HT-receptor agonists and antagonists. Although the serotonin agonists for the 5-HT1B,2C,3 receptors were ineffective, the effects were mimicked by the 5-HT1A-receptor agonists (8-OH-DPAT, 5-CT) and prevented by the 5-HT1A-receptor antagonist NAN-190. To look at the direct effects of 5-HT on inhibitory interneurons, we elicited monosynaptic IPSPs in the absence of excitatory synaptic transmission. In contrast to the polysynaptic IPSPs, monosynaptic IPSPs were not significantly affected by serotonin. Recordings from putative inhibitory interneurons revealed that their excitatory postsynaptic potentials (EPSPs) were reversibly reduced by serotonin. We conclude that serotonin suppresses polysynaptic inhibition in projection neurons of layers II and III of the EC by depression of EPSPs on inhibitory interneurons via 5-HT1A receptors.
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Affiliation(s)
- D Schmitz
- Department of Neurophysiology, Institute of Physiology, Charité, Humboldt University Berlin, Germany
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