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Pan W, Pan J, Zhao Y, Zhang H, Tang J. Serotonin Transporter Defect Disturbs Structure and Function of the Auditory Cortex in Mice. Front Neurosci 2021; 15:749923. [PMID: 34690685 PMCID: PMC8527018 DOI: 10.3389/fnins.2021.749923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 09/07/2021] [Indexed: 11/23/2022] Open
Abstract
Serotonin transporter (SERT) modulates the level of 5-HT and significantly affects the activity of serotonergic neurons in the central nervous system. The manipulation of SERT has lasting neurobiological and behavioral consequences, including developmental dysfunction, depression, and anxiety. Auditory disorders have been widely reported as the adverse events of these mental diseases. It is unclear how SERT impacts neuronal connections/interactions and what mechanism(s) may elicit the disruption of normal neural network functions in auditory cortex. In the present study, we report on the neuronal morphology and function of auditory cortex in SERT knockout (KO) mice. We show that the dendritic length of the fourth layer (L-IV) pyramidal neurons and the second-to-third layer (L-II/III) interneurons were reduced in the auditory cortex of the SERT KO mice. The number and density of dendritic spines of these neurons were significantly less than those of wild-type neurons. Also, the frequency-tonotopic organization of primary auditory cortex was disrupted in SERT KO mice. The auditory neurons of SERT KO mice exhibited border frequency tuning with high-intensity thresholds. These findings indicate that SERT plays a key role in development and functional maintenance of auditory cortical neurons. Auditory function should be examined when SERT is selected as a target in the treatment for psychiatric disorders.
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Affiliation(s)
- Wenlu Pan
- Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China.,Functional Nucleic Acid Basic and Clinical Research Center, Department of Physiology, School of Basic Medical Sciences, Changsha Medical College, Changsha, China
| | - Jing Pan
- Department of Otolaryngology Head and Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou, China.,Hearing Research Center, Southern Medical University, Guangzhou, China
| | - Yan Zhao
- Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Hongzheng Zhang
- Department of Otolaryngology Head and Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou, China.,Hearing Research Center, Southern Medical University, Guangzhou, China
| | - Jie Tang
- Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China.,Department of Otolaryngology Head and Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou, China.,Hearing Research Center, Southern Medical University, Guangzhou, China.,Key Laboratory of Mental Health of the Ministry of Education, Southern Medical University, Guangzhou, China
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2
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Awasthi JR, Tamada K, Overton ETN, Takumi T. Comprehensive topographical map of the serotonergic fibers in the male mouse brain. J Comp Neurol 2021; 529:1391-1429. [PMID: 32892368 DOI: 10.1002/cne.25027] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 08/14/2020] [Accepted: 08/26/2020] [Indexed: 11/11/2022]
Abstract
It is well established that serotonergic fibers distribute throughout the brain. Abnormal densities or patterns of serotonergic fibers have been implicated in neuropsychiatric disorders. Although many classical studies have examined the distribution pattern of serotonergic fibers, most of them were either limited to specific brain areas or had limitations in demonstrating the fine axonal morphology. In this study, we utilize male mice expressing green fluorescence protein under the serotonin transporter (SERT) promoter to map the topography of serotonergic fibers across the rostro-caudal extent of each brain area. We demonstrate previously unreported regional density and fine-grained anatomy of serotonergic fibers. Our findings include: (a) SERT fibers distribute abundantly in the thalamic nuclei close to the midline and dorsolateral areas, in most of the hypothalamic nuclei with few exceptions such as the median eminence and arcuate nuclei, and within the basal amygdaloid complex and lateral septal nuclei, (b) the source fibers of innervation of the hippocampus traverse through the septal nuclei before reaching its destination, (c) unique, filamentous type of straight terminal fibers within the nucleus accumbens, (d) laminar pattern of innervation in the hippocampus, olfactory bulb and cortex with heterogenicity in innervation density among the layers, (e) cortical labeling density gradually decreases rostro-caudally, (f) fibers traverse and distribute mostly within the gray matter, leaving the white fiber bundles uninnervated, and (g) most of the highly labeled nuclei and cortical areas have predominant anatomical connection to limbic structures. In conclusion, we provide novel, regionally specific insights on the distribution map of serotonergic fibers using transgenic mouse.
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Affiliation(s)
- Janak R Awasthi
- RIKEN Brain Science Institute, Wako, Japan.,Graduate School of Science and Engineering, Saitama University, Saitama, Japan
| | | | | | - Toru Takumi
- RIKEN Brain Science Institute, Wako, Japan.,Graduate School of Science and Engineering, Saitama University, Saitama, Japan.,Department of Physiology and Cell Biology, Kobe University School of Medicine, Kobe, Japan
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3
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Fukushima S, Kurganov E, Hiratsuka D, Miyata S. Effect of fluoxetine on proliferation and/or survival of microglia and oligodendrocyte progenitor cells in the fornix and corpus callosum of the mouse brain. Pharmacol Rep 2020; 72:340-349. [PMID: 32109308 DOI: 10.1007/s43440-020-00079-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 11/23/2019] [Accepted: 12/30/2019] [Indexed: 02/06/2023]
Abstract
BACKGROUND Fluoxetine is one of the most widely prescribed antidepressants and a selective inhibitor of presynaptic 5-HT transporters. The fornix is the commissural and projection fiber that transmits signals from the hippocampus to other parts of the brain and opposite site of hippocampus. The corpus callosum (CC) is the largest of the commissural fibers that link the cerebral cortex of the left and right cerebral hemispheres. These brain regions play pivotal roles in cognitive functions, and functional abnormalities in these regions have been implicated in the development of various brain diseases. The purpose of the present study was to investigate the effects of fluoxetine on the proliferation and/or survival of microglia and oligodendrocyte progenitor cells (OPCs) in the fornix and CC, the white matter connecting cortical-limbic system, of the adult mouse brain. METHODS The effects of fluoxetine on the proliferation and/or survival of microglia and OPCs were examined in lipopolysaccharide (LPS)-treated and normal mice. Proliferating cells were detected in mice that drank water containing the thymidine analog, bromodeoxyuridine (BrdU), using immunohistochemistry. RESULT Fluoxetine significantly attenuated LPS-induced increases in the number of BrdU-labeled microglia and morphological activation from the ramified to ameboid shape, and decreased the number of BrdU-labeled OPCs under basal conditions. CONCLUSIONS The present results indicate that fluoxetine exerts inhibitory effects on LPS-induced increases in the proliferation and/or survival and morphological activation of microglia and basal proliferation and/or survival of OPCs in the fornix and CC of adult mice.
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Affiliation(s)
- Shohei Fukushima
- Department of Applied Biology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan
| | - Erkin Kurganov
- Department of Applied Biology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan
| | - Daishi Hiratsuka
- Department of Applied Biology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan
| | - Seiji Miyata
- Department of Applied Biology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan.
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4
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Zhong X, Harris G, Smirnova L, Zufferey V, Sá RDCDSE, Baldino Russo F, Baleeiro Beltrao Braga PC, Chesnut M, Zurich MG, Hogberg HT, Hartung T, Pamies D. Antidepressant Paroxetine Exerts Developmental Neurotoxicity in an iPSC-Derived 3D Human Brain Model. Front Cell Neurosci 2020; 14:25. [PMID: 32153365 PMCID: PMC7047331 DOI: 10.3389/fncel.2020.00025] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Accepted: 01/28/2020] [Indexed: 02/04/2023] Open
Abstract
Selective serotonin reuptake inhibitors (SSRIs) are frequently used to treat depression during pregnancy. Various concerns have been raised about the possible effects of these drugs on fetal development. Current developmental neurotoxicity (DNT) testing conducted in rodents is expensive, time-consuming, and does not necessarily represent human pathophysiology. A human, in vitro testing battery to cover key events of brain development, could potentially overcome these challenges. In this study, we assess the DNT of paroxetine—a widely used SSRI which has shown contradictory evidence regarding effects on human brain development using a versatile, organotypic human induced pluripotent stem cell (iPSC)-derived brain model (BrainSpheres). At therapeutic blood concentrations, which lie between 20 and 60 ng/ml, Paroxetine led to an 80% decrease in the expression of synaptic markers, a 60% decrease in neurite outgrowth and a 40–75% decrease in the overall oligodendrocyte cell population, compared to controls. These results were consistently shown in two different iPSC lines and indicate that relevant therapeutic concentrations of Paroxetine induce brain cell development abnormalities which could lead to adverse effects.
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Affiliation(s)
- Xiali Zhong
- Center for Alternatives to Animal Testing (CAAT), Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States.,Guangdong Provincial Key Laboratory of Food, Nutrition and Health, Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou, China
| | - Georgina Harris
- Center for Alternatives to Animal Testing (CAAT), Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States
| | - Lena Smirnova
- Center for Alternatives to Animal Testing (CAAT), Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States
| | - Valentin Zufferey
- Department of Physiology, Lausanne and Swiss Centre for Applied Human Toxicology (SCAHT), University of Lausanne, Lausanne, Switzerland
| | | | - Fabiele Baldino Russo
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Patricia Cristina Baleeiro Beltrao Braga
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil.,Department of Obstetrics, School of Arts Sciences and Humanities, São Paulo, Brazil
| | - Megan Chesnut
- Center for Alternatives to Animal Testing (CAAT), Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States
| | - Marie-Gabrielle Zurich
- Department of Physiology, Lausanne and Swiss Centre for Applied Human Toxicology (SCAHT), University of Lausanne, Lausanne, Switzerland
| | - Helena T Hogberg
- Center for Alternatives to Animal Testing (CAAT), Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States
| | - Thomas Hartung
- Center for Alternatives to Animal Testing (CAAT), Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States.,CAAT-Europe, University of Konstanz, Konstanz, Germany
| | - David Pamies
- Center for Alternatives to Animal Testing (CAAT), Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States.,Department of Physiology, Lausanne and Swiss Centre for Applied Human Toxicology (SCAHT), University of Lausanne, Lausanne, Switzerland
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5
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Ferrer I. Oligodendrogliopathy in neurodegenerative diseases with abnormal protein aggregates: The forgotten partner. Prog Neurobiol 2018; 169:24-54. [DOI: 10.1016/j.pneurobio.2018.07.004] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2018] [Revised: 07/24/2018] [Accepted: 07/27/2018] [Indexed: 12/31/2022]
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6
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Fernández M, Mollinedo-Gajate I, Peñagarikano O. Neural Circuits for Social Cognition: Implications for Autism. Neuroscience 2017; 370:148-162. [PMID: 28729065 DOI: 10.1016/j.neuroscience.2017.07.013] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 07/01/2017] [Accepted: 07/07/2017] [Indexed: 12/28/2022]
Abstract
Social neuroscience, the study of the neurobiological basis of social behavior, has become a major area of current research in behavioral neuroscience and psychiatry, since many psychiatric disorders are characterized by social deficits. Social behavior refers to the behavioral response with regard to socially relevant information, and requires the perception and integration of social cues through a complex cognition process (i.e. social cognition) that involves attention, memory, motivation and emotion. Neurobiological and molecular mechanisms underlying social behavior are highly conserved across species, and inter- and intra-specific variability observed in social behavior can be explained to large extent by differential activity of this conserved neural network. Human functional magnetic resonance imaging (fMRI) studies have greatly informed about the brain structures and their connectivity networks that are important for social cognition. Animal research has been crucial for identifying specific circuits and molecular mechanisms that modulate this structural network. From a molecular neurobiology perspective, activity in these brain structures is coordinated by neuronal circuits modulated by several neurotransmitters and neuromodulators. Thus, quantitative variation in the levels, release and/or receptor density of these molecules could affect the observed behavioral response. The present review presents an overall framework of the components of the social brain circuitry and its modulation. By integrating multiple research approaches, from human fMRI studies to animal models we can start shedding light into how dysfunction in these circuits could lead to disorders of social-functioning such as Autism.
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Affiliation(s)
- Marta Fernández
- Department of Pharmacology, School of Medicine, University of the Basque Country (UPV/EHU), Leioa 48940, Spain
| | - Irene Mollinedo-Gajate
- Department of Pharmacology, School of Medicine, University of the Basque Country (UPV/EHU), Leioa 48940, Spain; Biomedical Research Networking Center in Mental Health (CIBERSAM), Spain
| | - Olga Peñagarikano
- Department of Pharmacology, School of Medicine, University of the Basque Country (UPV/EHU), Leioa 48940, Spain; Biomedical Research Networking Center in Mental Health (CIBERSAM), Spain.
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7
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Honório de Melo Martimiano P, de Sa Braga Oliveira A, Ferchaud-Roucher V, Croyal M, Aguesse A, Grit I, Ouguerram K, Lopes de Souza S, Kaeffer B, Bolaños-Jiménez F. Maternal protein restriction during gestation and lactation in the rat results in increased brain levels of kynurenine and kynurenic acid in their adult offspring. J Neurochem 2016; 140:68-81. [PMID: 27778340 DOI: 10.1111/jnc.13874] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Revised: 09/14/2016] [Accepted: 10/14/2016] [Indexed: 12/31/2022]
Abstract
Early malnutrition is a risk factor for depression and schizophrenia. Since the offspring of malnourished dams exhibit increased brain levels of serotonin (5-HT), a tryptophan-derived neurotransmitter involved in the pathophysiology of these mental disorders, it is believed that the deleterious effects of early malnutrition on brain function are due in large part to altered serotoninergic neurotransmission resulting from impaired tryptophan (Trp) metabolism. However, tryptophan is also metabolized through the kynurenine (KYN) pathway yielding several neuroactive compounds including kynurenic (KA), quinolinic (QA) and xanthurenic (XA) acids. Nevertheless, the impact of perinatal malnutrition on brain kynurenine pathway metabolism has not been examined to date. Here, we used ultra-performance liquid chromatography-tandem mass spectrometry for the simultaneous quantification of tryptophan and a set of seven compounds spanning its metabolism through the serotonin and kynurenine pathways, in the brain of embryos and adult offspring of rat dams fed a protein-restricted (PR) diet. Protein-restricted embryos showed reduced brain levels of Trp, serotonin and KA, but not of KYN, XA, or QA. In contrast, PR adult rats exhibited enhanced levels of Trp in the brainstem and cortex along with increased concentrations of 5-HT, kynurenine and XA. The levels of XA and KA were also increased in the hippocampus of adult PR rats. These results show that early protein deficiency induces selective and long-lasting changes in brain kynurenine metabolism. Given the regulatory role of KYN pathway metabolites on brain development and function, these changes might contribute to the risk of developing psychiatric disorders induced by early malnutrition.
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Affiliation(s)
- Paula Honório de Melo Martimiano
- UMR 1280 Physiologie des Adaptations Nutritionnelles, INRA-Université de Nantes, Nantes, France.,Departamento de Anatomia, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil
| | - André de Sa Braga Oliveira
- UMR 1280 Physiologie des Adaptations Nutritionnelles, INRA-Université de Nantes, Nantes, France.,Departamento de Anatomia, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil
| | - Véronique Ferchaud-Roucher
- UMR 1280 Physiologie des Adaptations Nutritionnelles, INRA-Université de Nantes, Nantes, France.,Centre de Recherche en Nutrition Humaine de l'Ouest, Nantes, France
| | - Mikaël Croyal
- UMR 1280 Physiologie des Adaptations Nutritionnelles, INRA-Université de Nantes, Nantes, France.,Centre de Recherche en Nutrition Humaine de l'Ouest, Nantes, France
| | - Audrey Aguesse
- UMR 1280 Physiologie des Adaptations Nutritionnelles, INRA-Université de Nantes, Nantes, France.,Centre de Recherche en Nutrition Humaine de l'Ouest, Nantes, France
| | - Isabelle Grit
- UMR 1280 Physiologie des Adaptations Nutritionnelles, INRA-Université de Nantes, Nantes, France
| | - Khadija Ouguerram
- UMR 1280 Physiologie des Adaptations Nutritionnelles, INRA-Université de Nantes, Nantes, France
| | - Sandra Lopes de Souza
- Departamento de Anatomia, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil
| | - Bertrand Kaeffer
- UMR 1280 Physiologie des Adaptations Nutritionnelles, INRA-Université de Nantes, Nantes, France
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8
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Muller CL, Anacker AMJ, Veenstra-VanderWeele J. The serotonin system in autism spectrum disorder: From biomarker to animal models. Neuroscience 2016; 321:24-41. [PMID: 26577932 PMCID: PMC4824539 DOI: 10.1016/j.neuroscience.2015.11.010] [Citation(s) in RCA: 308] [Impact Index Per Article: 38.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Revised: 10/26/2015] [Accepted: 11/04/2015] [Indexed: 02/02/2023]
Abstract
Elevated whole blood serotonin, or hyperserotonemia, was the first biomarker identified in autism spectrum disorder (ASD) and is present in more than 25% of affected children. The serotonin system is a logical candidate for involvement in ASD due to its pleiotropic role across multiple brain systems both dynamically and across development. Tantalizing clues connect this peripheral biomarker with changes in brain and behavior in ASD, but the contribution of the serotonin system to ASD pathophysiology remains incompletely understood. Studies of whole blood serotonin levels in ASD and in a large founder population indicate greater heritability than for the disorder itself and suggest an association with recurrence risk. Emerging data from both neuroimaging and postmortem samples also indicate changes in the brain serotonin system in ASD. Genetic linkage and association studies of both whole blood serotonin levels and of ASD risk point to the chromosomal region containing the serotonin transporter (SERT) gene in males but not in females. In ASD families with evidence of linkage to this region, multiple rare SERT amino acid variants lead to a convergent increase in serotonin uptake in cell models. A knock-in mouse model of one of these variants, SERT Gly56Ala, recapitulates the hyperserotonemia biomarker and shows increased brain serotonin clearance, increased serotonin receptor sensitivity, and altered social, communication, and repetitive behaviors. Data from other rodent models also suggest an important role for the serotonin system in social behavior, in cognitive flexibility, and in sensory development. Recent work indicates that reciprocal interactions between serotonin and other systems, such as oxytocin, may be particularly important for social behavior. Collectively, these data point to the serotonin system as a prime candidate for treatment development in a subgroup of children defined by a robust, heritable biomarker.
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Affiliation(s)
- C L Muller
- Vanderbilt Brain Institute, Vanderbilt University, 465 21st Avenue South, Nashville, TN 37232, USA.
| | - A M J Anacker
- Department of Psychiatry, Columbia University, 1051 Riverside Drive, Mail Unit 78, New York, NY 10032, USA.
| | - J Veenstra-VanderWeele
- Sackler Institute for Developmental Psychobiology, Department of Psychiatry, Columbia University; Center for Autism and the Developing Brain, New York Presbyterian Hospital; New York State Psychiatric Institute, 1051 Riverside Drive, Mail Unit 78, New York, NY 10032, USA.
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9
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Marinelli C, Bertalot T, Zusso M, Skaper SD, Giusti P. Systematic Review of Pharmacological Properties of the Oligodendrocyte Lineage. Front Cell Neurosci 2016; 10:27. [PMID: 26903812 PMCID: PMC4751280 DOI: 10.3389/fncel.2016.00027] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 01/25/2016] [Indexed: 12/12/2022] Open
Abstract
Oligodendrogenesis and oligodendrocyte precursor maturation are essential processes during the course of central nervous system development, and lead to the myelination of axons. Cells of the oligodendrocyte lineage are generated in the germinal zone from migratory bipolar oligodendrocyte precursor cells (OPCs), and acquire cell surface markers as they mature and respond specifically to factors which regulate proliferation, migration, differentiation, and survival. Loss of myelin underlies a wide range of neurological disorders, some of an autoimmune nature—multiple sclerosis probably being the most prominent. Current therapies are based on the use of immunomodulatory agents which are likely to promote myelin repair (remyelination) indirectly by subverting the inflammatory response, aspects of which impair the differentiation of OPCs. Cells of the oligodendrocyte lineage express and are capable of responding to a diverse array of ligand-receptor pairs, including neurotransmitters and nuclear receptors such as γ-aminobutyric acid, glutamate, adenosine triphosphate, serotonin, acetylcholine, nitric oxide, opioids, prostaglandins, prolactin, and cannabinoids. The intent of this review is to provide the reader with a synopsis of our present state of knowledge concerning the pharmacological properties of the oligodendrocyte lineage, with particular attention to these receptor-ligand (i.e., neurotransmitters and nuclear receptor) interactions that can influence oligodendrocyte migration, proliferation, differentiation, and myelination, and an appraisal of their therapeutic potential. For example, many promising mediators work through Ca2+ signaling, and the balance between Ca2+ influx and efflux can determine the temporal and spatial properties of oligodendrocytes (OLs). Moreover, Ca2+ signaling in OPCs can influence not only differentiation and myelination, but also process extension and migration, as well as cell death in mature mouse OLs. There is also evidence that oligodendroglia exhibit Ca2+ transients in response to electrical activity of axons for activity-dependent myelination. Cholinergic antagonists, as well as endocannabinoid-related lipid-signaling molecules target OLs. An understanding of such pharmacological pathways may thus lay the foundation to allow its leverage for therapeutic benefit in diseases of demyelination.
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Affiliation(s)
- Carla Marinelli
- Department of Pharmaceutical and Pharmacological Sciences, University of Padua Padua, Italy
| | - Thomas Bertalot
- Department of Pharmaceutical and Pharmacological Sciences, University of Padua Padua, Italy
| | - Morena Zusso
- Department of Pharmaceutical and Pharmacological Sciences, University of Padua Padua, Italy
| | - Stephen D Skaper
- Department of Pharmaceutical and Pharmacological Sciences, University of Padua Padua, Italy
| | - Pietro Giusti
- Department of Pharmaceutical and Pharmacological Sciences, University of Padua Padua, Italy
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10
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Fan LW, Bhatt A, Tien LT, Zheng B, Simpson KL, Lin RCS, Cai Z, Kumar P, Pang Y. Exposure to serotonin adversely affects oligodendrocyte development and myelination in vitro. J Neurochem 2015; 133:532-43. [PMID: 25382136 DOI: 10.1111/jnc.12988] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Revised: 10/27/2014] [Accepted: 10/30/2014] [Indexed: 11/28/2022]
Abstract
Serotonin (5-hydroxytryptamine, 5-HT) has been implicated to play critical roles in early neural development. Recent reports have suggested that perinatal exposure to selective serotonin reuptake inhibitors (SSRIs) resulted in cortical network miswiring, abnormal social behavior, callosal myelin malformation, as well as oligodendrocyte (OL) pathology in rats. To gain further insight into the cellular and molecular mechanisms underlying SSRIs-induced OL and myelin abnormalities, we investigated the effect of 5-HT exposure on OL development, cell death, and myelination in cell culture models. First, we showed that 5-HT receptor 1A and 2A subtypes were expressed in OL lineages, using immunocytochemistry, Western blot, as well as intracellular Ca(2+) measurement. We then assessed the effect of serotonin exposure on the lineage development, expression of myelin proteins, cell death, and myelination, in purified OL and neuron-OL myelination cultures. For pure OL cultures, our results showed that 5-HT exposure led to disturbance of OL development, as indicated by aberrant process outgrowth and reduced myelin proteins expression. At higher doses, such exposure triggered a development-dependent cell death, as immature OLs exhibited increasing susceptibility to 5-HT treatment compared to OL progenitor cells (OPC). We showed further that 5-HT-induced immature OL death was mediated at least partially via 5-HT2A receptor, since cell death could be mimicked by 5-HT2A receptor agonist 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane hydrochloride, (±)-2,5-dimethoxy-4-iodoamphetamine hydrochloride, but atten-uated by pre-treatment with 5-HT2A receptor antagonist ritanserin. Utilizing a neuron-OL myelination co-culture model, our data showed that 5-HT exposure significantly reduced the number of myelinated internodes. In contrast to cell injury observed in pure OL cultures, 5-HT exposure did not lead to OL death or reduced OL density in neuron-OL co-cultures. However, abnormal patterns of contactin-associated protein (Caspr) clustering were observed at the sites of Node of Ranvier, suggesting that 5-HT exposure may affect other axon-derived factors for myelination. In summary, this is the first study to demonstrate that manipulation of serotonin levels affects OL development and myelination, which may contribute to altered neural connectivity noted in SSRIs-treated animals. The current in vitro study demonstrated that exposure to high level of serotonin (5-HT) led to aberrant oligodendrocyte (OL) development, cell injury, and myelination deficit. We propose that elevated extracellular serotonin levels in the fetal brain, such as upon the use of selective serotonin reuptake inhibitors (SSRIs) during pregnancy, may adversely affect OL development and/or myelination, thus contributing to altered neural connectivity seen in Autism Spectrum Disorders. OPC = oligodendrocyte progenitor cell.
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Affiliation(s)
- Lir-Wan Fan
- Department of Pediatrics, University of Mississippi Medical Center, Jackson, Mississippi, USA
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11
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Weber DN, Hoffmann RG, Hoke ES, Tanguay RL. Bisphenol A exposure during early development induces sex-specific changes in adult zebrafish social interactions. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2015; 78:50-66. [PMID: 25424546 PMCID: PMC4246420 DOI: 10.1080/15287394.2015.958419] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Developmental bisphenol A (BPA) exposure is associated with adverse behavioral effects, although underlying modes of action remain unclear. Because BPA is a suspected xenoestrogen, the objective was to identify sex-based changes in adult zebrafish social behavior developmentally exposed to BPA (0.0, 0.1, or 1 μM) or one of two control compounds (0.1 μM 17β-estradiol [E2], and 0.1 μM GSK4716, a synthetic estrogen-related receptor γ ligand). A test chamber was divided lengthwise so each arena held one fish unable to detect the presence of the other fish. A mirror was inserted at one end of each arena; baseline activity levels were determined without mirror. Arenas were divided into three computer-generated zones to represent different distances from mirror image. Circadian rhythm patterns were evaluated at 1-3 (= AM) and 5-8 (= PM) h postprandial. Adult zebrafish were placed into arenas and monitored by digital camera for 5 min. Total distance traveled, percent of time spent at mirror image, and number of attacks on mirror image were quantified. E2, GSK4716, and all BPA treatments dampened male activity and altered male circadian activity patterns; there was no marked effect on female activity. BPA induced nonmonotonic effects (response curve changes direction within range of concentrations examined) on male percent of time at mirror only in AM. All treatments produced increased percent of time at the mirror during PM. Male attacks on the mirror were reduced by BPA exposure only during AM. There were sex-specific effects of developmental BPA on social interactions, and time of day of observation affected results.
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Affiliation(s)
- Daniel N. Weber
- Children’s Environmental Health Sciences Core Center, University of Wisconsin-Milwaukee
- To Whom Correspondence Should Be Addressed: , 600 E. Greenfield Ave, Milwaukee, WI 53204, (414) 382-1726
| | | | | | - Robert L. Tanguay
- College of Agricultural Sciences, Department of Environmental & Molecular Toxicology, Oregon State University
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Kinast K, Peeters D, Kolk SM, Schubert D, Homberg JR. Genetic and pharmacological manipulations of the serotonergic system in early life: neurodevelopmental underpinnings of autism-related behavior. Front Cell Neurosci 2013; 7:72. [PMID: 23781172 PMCID: PMC3679613 DOI: 10.3389/fncel.2013.00072] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2013] [Accepted: 04/30/2013] [Indexed: 12/28/2022] Open
Abstract
Serotonin, in its function as neurotransmitter, is well-known for its role in depression, autism and other neuropsychiatric disorders, however, less known as a neurodevelopmental factor. The serotonergic system is one of the earliest to develop during embryogenesis and early changes in serotonin levels can have large consequences for the correct development of specific brain areas. The regulation and functioning of serotonin is influenced by genetic risk factors, such as the serotonin transporter polymorphism in humans. This polymorphism is associated with anxiety-related symptoms, changes in social behavior, and cortical gray and white matter changes also seen in patients suffering from autism spectrum disorders (ASD). The human polymorphism can be mimicked by the knockout of the serotonin transporter in rodents, which are as a model system therefore vital to explore the precise neurobiological mechanisms. Moreover, there are pharmacological challenges influencing serotonin in early life, like prenatal/neonatal exposure to selective serotonin reuptake inhibitors (SSRI) in depressed pregnant women. There is accumulating evidence that this dysregulation of serotonin during critical phases of brain development can lead to ASD-related symptoms in children, and reduced social behavior and increased anxiety in rodents. Furthermore, prenatal valproic acid (VPA) exposure, a mood stabilizing drug which is also thought to interfere with serotonin levels, has the potency to induce ASD-like symptoms and to affect the development of the serotonergic system. Here, we review and compare the neurodevelopmental and behavioral consequences of serotonin transporter gene variation, and prenatal SSRI and VPA exposure in the context of ASD.
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Affiliation(s)
- Karsten Kinast
- Behavioural Neurogenetics, Department of Cognitive Neuroscience, Centre for Neuroscience, Donders Institute for Brain, Cognition, and Behaviour, Radboud University Nijmegen Medical Centre Nijmegen, Netherlands
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13
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Ejaculatory Responses are Inhibited by a New Chemical Entity, DA-8031, in Preclinical Rodent Models of Ejaculation. Urology 2013; 81:920.e13-8. [DOI: 10.1016/j.urology.2012.12.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 11/30/2012] [Accepted: 12/04/2012] [Indexed: 01/17/2023]
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14
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Narboux-Nême N, Angenard G, Mosienko V, Klempin F, Pitychoutis PM, Deneris E, Bader M, Giros B, Alenina N, Gaspar P. Postnatal growth defects in mice with constitutive depletion of central serotonin. ACS Chem Neurosci 2013; 4:171-81. [PMID: 23336056 DOI: 10.1021/cn300165x] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2012] [Accepted: 12/14/2012] [Indexed: 12/31/2022] Open
Abstract
Although the trophic actions of serotonin (5-HT) are well established, only few developmental defects have been reported in mouse strains with constitutive hyposerotonergia. We analyzed postnatal growth and cortical development in three different mutant mouse strains with constitutive reductions in central 5-HT levels. We compared two previously published mouse strains with severe (-95%) depletions of 5-HT, the tryptophan hydroxylase (Tph) 2(-/-) mouse line and VMAT2(sert-cre) mice, with a new strain, in which VMAT2 deletion is driven by Pet1 (VMAT2(pet1-cre)) in 5-HT raphe neurons leading to partial (-75%) reduction in brain 5-HT levels. We find that normal embryonic growth and postnatal growth retardation are common features of all these mouse strains. Postnatal growth retardation varied from mild to severe according to the extent of the brain 5-HT reduction and gender. Normal growth was reinstated in VMAT2(sert-cre) mice by reconstituting central 5-HT stores. Growth abnormalities could not be linked to altered food intake or temperature control. Morphological study of the cerebral cortex over postnatal development showed a delayed maturation of the upper cortical layers in the VMAT2(sert-cre) and Tph2(-/-) mice, but not in the VMAT2(pet1-cre) mice. No changes in layer-specific gene expression or morphological alterations of barrel cortex development were found. Overall, these observations sustain the notion that central 5-HT signaling is required for the preweaning growth spurt of mouse pups. Brain development appeared to be immune to severe central 5-HT depletion for its overall growth during prenatal life, whereas reduced brain growth and delayed cortical maturation development occurred during postnatal life. Reduced developmental 5-HT signaling during postnatal development might modulate the function and fine structure of neural circuits in ways that affect adult behavior.
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Affiliation(s)
- Nicolas Narboux-Nême
- INSERM, UMR-S 839, Institut du Fer à
Moulin, 17, rue du Fer à Moulin, 75005 Paris, France
- Université Pierre et Marie Curie (UPMC), Paris 06, Paris, France
| | - Gaelle Angenard
- INSERM, UMR-S 839, Institut du Fer à
Moulin, 17, rue du Fer à Moulin, 75005 Paris, France
- Université Pierre et Marie Curie (UPMC), Paris 06, Paris, France
| | | | | | - Pothitos M. Pitychoutis
- INSERM, UMR-S 839, Institut du Fer à
Moulin, 17, rue du Fer à Moulin, 75005 Paris, France
- Université Pierre et Marie Curie (UPMC), Paris 06, Paris, France
| | - Evan Deneris
- Case Western Reserve University, Cleveland, Ohio 44101, United States
| | - Michael Bader
- Max-Delbrueck-Center for Molecular Medicine, 13125 Berlin-Buch, Germany
| | - Bruno Giros
- Université Pierre et Marie Curie (UPMC), Paris 06, Paris, France
- CNRS UMR 7224, 9 Quai St Bernard, 75005 Paris, France
- Douglas Hospital, Department of Psychiatry, McGill University, Montreal, Canada
| | - Natalia Alenina
- Max-Delbrueck-Center for Molecular Medicine, 13125 Berlin-Buch, Germany
| | - Patricia Gaspar
- INSERM, UMR-S 839, Institut du Fer à
Moulin, 17, rue du Fer à Moulin, 75005 Paris, France
- Université Pierre et Marie Curie (UPMC), Paris 06, Paris, France
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15
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van Kleef ESB, Gaspar P, Bonnin A. Insights into the complex influence of 5-HT signaling on thalamocortical axonal system development. Eur J Neurosci 2012; 35:1563-72. [PMID: 22607002 DOI: 10.1111/j.1460-9568.2012.8096.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The topographic organization of the thalamocortical axons (TCAs) in the barrel field (BF) in the rodent primary somatosensory cortex results from a succession of temporally and spatially precise developmental events. Prenatally, growth and guidance mechanisms enable TCAs to navigate through the forebrain and reach the cortex. Postnatally, TCAs grow into the cortex, and the refinement of their terminal arborization pattern in layer IV creates barrel-like structures. The combined results of studies performed over the past 20 years clearly show that serotonin (5-hydroxytryptamine; 5-HT) signaling modulates these pre- and early postnatal developmental processes. In this context, 5-HT signaling can purposely be described as 'modulating' rather than 'controlling' because developmental alterations of 5-HT synthesis, uptake or degradation either have a dramatic, moderate or no effect at all on TCA pathway and BF formation. In this review we summarize and compare the outcomes of diverse pharmacological and genetic manipulations of 5-HT signaling on TCA pathway and BF formation, in an attempt to understand these discrepancies.
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16
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Flores-Cruz GM, Escobar A. Reduction of serotonergic neurons in the dorsal raphe due to chronic prenatal administration of a tryptophan-free diet. Int J Dev Neurosci 2012; 30:63-7. [PMID: 22244887 DOI: 10.1016/j.ijdevneu.2012.01.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Accepted: 01/01/2012] [Indexed: 01/24/2023] Open
Abstract
Serotonin (5-HT) is a widely studied neurotransmitter which plays an important role in the development and proper functioning of the organism throughout life. The appearance of 5-HT system early in ontogeny suggests the hypothesis that 5-HT plays a regulatory role in neurodevelopment. This study investigated the effect of administration of a tryptophan deficient diet during prenatal development on the morphology and cell population of the dorsal raphe. The experimental diet, containing balanced amounts of carbohydrates, lipids and proteins, was provided to a time-mated group of rats from gestational day 5 until delivery. Control groups were fed with (i) the experimental diet formulation with 0.2% tryptophan added to the mixture, or (ii) a regular chow diet. At delivery, five pups per dam were euthanized. Body and brain weight was measured and brain sections were processed for immunohistochemistry for tryptophan hydroxylase (TrpH) and whole brain 5-HT analysis. Sections containing dorsal raphe were photographed with a light microscope and TrpH positive neurons quantified. Brain weights in the tryptophan deprived group showed no difference as compared with controls while body weights were reduced by 25%. Total numbers of serotonergic neurons at the dorsal raphe in the prenatal tryptophan deficient pups were reduced by 35%. A regional analysis of the dorsal raphe indicated a marked cellular reduction in the medial and caudal sections of the nucleus, which contains the majority of serotonergic neurons, in the tryptophan deprived condition. Quantitative 5-HT analysis showed that the brain concentration was similar among conditions. In conclusion, gestational tryptophan deprivation exerts adverse effects on the development of the 5-HT system, particularly in the dorsal raphe, manifested by decreased numbers of serotonergic neurons as well as altered topography in this important nucleus.
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Affiliation(s)
- Guadalupe M Flores-Cruz
- Cellular Biology & Physiology Department, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico.
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17
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Perinatal antidepressant exposure alters cortical network function in rodents. Proc Natl Acad Sci U S A 2011; 108:18465-70. [PMID: 22025710 DOI: 10.1073/pnas.1109353108] [Citation(s) in RCA: 152] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Serotonin (5-HT) plays a key role in early brain development, and manipulation of 5-HT levels during this period can have lasting neurobiological and behavioral consequences. It is unclear how perinatal exposure to drugs, such as selective serotonin reuptake inhibitors (SSRIs), impacts cortical neural network function and what mechanism(s) may elicit the disruption of normal neuronal connections/interactions. In this article, we report on cortical wiring organization after pre- and postnatal exposure to the SSRI citalopram. We show that manipulation of 5-HT during early development in both in vitro and in vivo models disturbs characteristic chemoarchitectural and electrophysiological brain features, including changes in raphe and callosal connections, sensory processing, and myelin sheath formation. Also, drug-exposed rat pups exhibit neophobia and disrupted juvenile play behavior. These findings indicate that 5-HT homeostasis is required for proper brain maturation and that fetal/infant exposure to SSRIs should be examined in humans, particularly those with developmental dysfunction, such as autism.
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18
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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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19
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Bearer EL, Zhang X, Janvelyan D, Boulat B, Jacobs RE. Reward circuitry is perturbed in the absence of the serotonin transporter. Neuroimage 2009; 46:1091-104. [PMID: 19306930 DOI: 10.1016/j.neuroimage.2009.03.026] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2008] [Revised: 03/10/2009] [Accepted: 03/11/2009] [Indexed: 10/21/2022] Open
Abstract
The serotonin transporter (SERT) modulates the entire serotonergic system in the brain and influences both the dopaminergic and norepinephrinergic systems. These three systems are intimately involved in normal physiological functioning of the brain and implicated in numerous pathological conditions. Here we use high-resolution magnetic resonance imaging (MRI) and spectroscopy to elucidate the effects of disruption of the serotonin transporter in an animal model system: the SERT knock-out mouse. Employing manganese-enhanced MRI, we injected Mn(2+) into the prefrontal cortex and obtained 3D MR images at specific time points in cohorts of SERT and normal mice. Statistical analysis of co-registered datasets demonstrated that active circuitry originating in the prefrontal cortex in the SERT knock-out is dramatically altered, with a bias towards more posterior areas (substantia nigra, ventral tegmental area, and Raphé nuclei) directly involved in the reward circuit. Injection site and tracing were confirmed with traditional track tracers by optical microscopy. In contrast, metabolite levels were essentially normal in the SERT knock-out by in vivo magnetic resonance spectroscopy and little or no anatomical differences between SERT knock-out and normal mice were detected by MRI. These findings point to modulation of the limbic cortical-ventral striatopallidal by disruption of SERT function. Thus, molecular disruptions of SERT that produce behavioral changes also alter the functional anatomy of the reward circuitry in which all the monoamine systems are involved.
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Affiliation(s)
- Elaine L Bearer
- Biological Imaging Center, Beckman Institute, California Institute of Technology, Pasadena, CA 91125, USA
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20
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21
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Abstract
Improving clinical tests are allowing us to more precisely classify autism spectrum disorders and diagnose them at earlier ages. This raises the possibility of earlier and potentially more effective therapeutic interventions. To fully capitalize on this opportunity, however, will require better understanding of the neurobiological changes underlying this devastating group of developmental disorders. It is becoming clear that the normal trajectory of neurodevelopment is altered in autism, with aberrations in brain growth, neuronal patterning and cortical connectivity. Changes to the structure and function of synapses and dendrites have also been strongly implicated in the pathology of autism by morphological, genetic and animal modeling studies. Finally, environmental factors are likely to interact with the underlying genetic profile, and foster the clinical heterogeneity seen in autism spectrum disorders. In this review we attempt to link the molecular pathways altered in autism to the neurodevelopmental and clinical changes that characterize the disease. We focus on signaling molecules such as neurotrophin, Reelin, PTEN and hepatocyte growth factor, neurotransmitters such as serotonin and glutamate, and synaptic proteins such as neurexin, SHANK and neuroligin. We also discuss evidence implicating oxidative stress, neuroglial activation and neuroimmunity in autism.
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Affiliation(s)
- Carlos A Pardo
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21287. USA.
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22
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Borue X, Chen J, Condron BG. Developmental effects of SSRIs: lessons learned from animal studies. Int J Dev Neurosci 2007; 25:341-7. [PMID: 17706396 PMCID: PMC2277509 DOI: 10.1016/j.ijdevneu.2007.06.003] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2007] [Accepted: 06/19/2007] [Indexed: 10/23/2022] Open
Abstract
Selective serotonin reuptake inhibitors (SSRIs) are utilized in the treatment of depression in pregnant and lactating women. SSRIs may be passed to the fetus through the placenta and the neonate through breastfeeding, potentially exposing them to SSRIs during peri- and postnatal development. However, the long-term effects of this SSRI exposure are still largely unknown. The simplicity and genetic amenability of model organisms provides a critical experimental advantage compared to studies with humans. This review will assess the current research done in animals that sheds light on the role of serotonin during development and the possible effects of SSRIs. Experimental studies in rodents show that administration of SSRIs during a key developmental window creates changes in brain circuitry and maladaptive behaviors that persist into adulthood. Similar changes result from the inhibition of the serotonin transporter or monoamine oxidase, implicating these two regulators of serotonin signaling in developmental changes. Understanding the role of serotonin in brain development is critical to identifying the possible effects of SSRI exposure.
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Affiliation(s)
- Xenia Borue
- University of Virginia Medical Scientist Training Program and University of Virginia, Neuroscience Graduate Program, Charlottesville, VA 22904
- University of Virginia Department of Biology, Charlottesville, VA 22904
| | - John Chen
- University of Virginia Medical Scientist Training Program and University of Virginia, Neuroscience Graduate Program, Charlottesville, VA 22904
- University of Virginia Department of Biology, Charlottesville, VA 22904
| | - Barry G. Condron
- University of Virginia Department of Biology, Charlottesville, VA 22904
- * Corresponding author: Barry G. Condron, University of Virginia, Department of Biology, Gilmer Hall 071, Box 400328, Charlottesville, VA 22904, Phone (434)243-6794, FAX (434)243-5315,
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23
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Altamura C, Dell'Acqua ML, Moessner R, Murphy DL, Lesch KP, Persico AM. Altered Neocortical Cell Density and Layer Thickness in Serotonin Transporter Knockout Mice: A Quantitation Study. Cereb Cortex 2006; 17:1394-401. [PMID: 16905592 DOI: 10.1093/cercor/bhl051] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The neurotransmitter serotonin (5-HT) plays morphogenetic roles during development, and their alteration could contribute to autism pathogenesis in humans. To further characterize 5-HT's contributions to neocortical development, we assessed the thickness and neuronal cell density of various cerebral cortical areas in serotonin transporter (5-HTT) knockout (ko) mice, characterized by elevated extracellular 5-HT levels. The thickness of layer IV is decreased in 5-HTT ko mice compared with wild-type (wt) mice. The overall effect on cortical thickness, however, depends on the genetic background of the mice. Overall cortical thickness is decreased in many cortical areas of 5-HTT ko mice with a mixed c129-CD1-C57BL/6J background. Instead, 5-HTT ko mice backcrossed into the C57BL/6J background display increases in supragranular and infragranular layers, which compensate entirely for decreased layer IV thickness, resulting in unchanged or even enhanced cortical thickness. Moreover, significant increases in neuronal cell density are found in 5-HTT ko mice with a C57BL/6J background (wt:hz:ko ratio = 1.00:1.04:1.17) but not in the mixed c129-CD1-C57BL/6J 5-HTT ko animals. These results provide evidence of 5-HTT gene effects on neocortical morphology in epistatic interaction with genetic variants at other loci and may model the effect of functional 5-HTT gene variants on neocortical development in autism.
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Affiliation(s)
- C Altamura
- Laboratory of Molecular Psychiatry and Neurogenetics, University Campus Bio-Medico, Via Longoni 83, I-00155 Rome, Italy
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24
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Levin M, Buznikov GA, Lauder JM. Of minds and embryos: left-right asymmetry and the serotonergic controls of pre-neural morphogenesis. Dev Neurosci 2006; 28:171-85. [PMID: 16679764 DOI: 10.1159/000091915] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2005] [Accepted: 10/12/2005] [Indexed: 01/22/2023] Open
Abstract
Serotonin is a clinically important neurotransmitter regulating diverse aspects of cognitive function, sleep, mood, and appetite. Increasingly, it is becoming appreciated that serotonin signaling among non-neuronal cells is a novel patterning mechanism existing throughout diverse phyla. Here, we review the evidence implicating serotonergic signaling in embryonic morphogenesis, including gastrulation, craniofacial and bone patterning, and the generation of left-right asymmetry. We propose two models suggesting movement of neurotransmitter molecules as a novel mechanism for how bioelectrical events may couple to downstream signaling cascades and gene activation networks. The discovery of serotonin-dependent patterning events occurring long before the development of the nervous system opens exciting new avenues for future research in evolutionary, developmental, and clinical biology.
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Affiliation(s)
- Michael Levin
- The Forsyth Institute, and Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA 02115, USA.
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25
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Margret CP, Li CX, Chappell TD, Elberger AJ, Matta SG, Waters RS. Prenatal alcohol exposure delays the development of the cortical barrel field in neonatal rats. Exp Brain Res 2006; 172:1-13. [PMID: 16506013 DOI: 10.1007/s00221-005-0319-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2005] [Accepted: 11/03/2005] [Indexed: 10/25/2022]
Abstract
In-utero alcohol exposure produces sensorimotor developmental abnormalities that often persist into adulthood. The rodent cortical barrel field associated with the representation of the body surface was used as our model system to examine the effect of prenatal alcohol exposure (PAE) on early somatosensory cortical development. In this study, pregnant female rats were intragastrically gavaged daily with high doses of alcohol (6 gm/kg body weight) throughout the first 20 days of pregnancy. Blood alcohol levels were measured in the pregnant dams on gestational days 13 (G13) and G20. The ethanol treated group (EtOH) was compared to the normal control chowfed (CF) group, nutritionally matched pairfed (PF) group, and cross-foster (XF) group. Cortical barrel development was examined in pups across all treatment groups from G25, corresponding to postnatal day 2 (P2), to G32 corresponding to P9. The EtOH and control group pups were weighed, anesthetized, and perfused. Brains were removed and weighed with, and without cerebellum and olfactory bulbs, and neocortex was removed and weighed. Cortices were then flattened, sectioned tangentially, and stained with a metabolic marker, cytochrome oxidase (CO) to reveal the barrel field. Progression of barrel development was distinguished into three categories: (a) absent, (b) cloudy barrel-like pattern, and (c) well-formed barrels with intervening septae. The major findings are: (1) PAE delayed barrel field development by one or more days, (2) the barrel field first appeared as a cloudy pattern that gave way on subsequent days to an adult-like pattern with clearly demarcated intervening septal regions, (3) the barrel field developed differentially in a lateral-to-medial gradient in both alcohol and control groups, (4) PAE delayed birth by one or more days in 53% of the pups, (5) regardless of whether pups were born on G23 (normal expected birth date for non-alcohol controls) or as in the case for the alcohol-delayed pups born as late as G27, the barrel field was never present at birth suggesting the importance of postnatal experience on barrel field development, and (6) PAE did not disrupt the normal barrel field pattern, although both total body and brain weights were compromised. These findings suggest that PAE delays the development of the somatosensory cortex (SI); such delays may interfere with timing and formation of cortical circuits. It is unknown whether other nuclei along the somatosensory pathway undergo similar delays in development or if PAE selectively disrupts cortical circuitry.
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Affiliation(s)
- Cecilia P Margret
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, College of Medicine, 855 Monroe Avenue, Memphis, TN 38163, USA
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26
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Fukumoto T, Blakely R, Levin M. Serotonin transporter function is an early step in left-right patterning in chick and frog embryos. Dev Neurosci 2006; 27:349-63. [PMID: 16280633 DOI: 10.1159/000088451] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2005] [Accepted: 04/22/2005] [Indexed: 01/03/2023] Open
Abstract
The neurotransmitter serotonin has been shown to regulate a number of embryonic patterning events in addition to its crucial role in the nervous system. Here, we examine the role of two serotonin transporters, the plasma membrane serotonin transporter (SERT) and the vesicular monoamine transporter (VMAT), in embryonic left-right asymmetry. Pharmacological or genetic inhibitors of either SERT or VMAT specifically randomized the laterality of the heart and viscera in Xenopus embryos. This effect takes place during cleavage stages, and is upstream of the left-sided gene XNR-1. Targeted microinjection of an SERT-dominant negative construct confirmed the necessity for SERT function in embryonic laterality and revealed that the descendants of the right ventral blastomere are the most dependent upon SERT signaling in left-right patterning. Moreover, the importance of SERT and VMAT in laterality is conserved in chick embryos, being upstream of the early left-sided gene Shh. Endogenous transcripts of SERT and VMAT are expressed from the initiation of the primitive streak in chick and are asymmetrically expressed in Hensen's node. Taken together our data characterize two new right-sided markers in chick gastrulation, identify a novel, early component of the left-right pathway in two vertebrate species, and reveal a new biological role for serotonin transport.
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Affiliation(s)
- Takahiro Fukumoto
- Cytokine Biology Department, The Forsyth Institute, Harvard Medical School, Boston, Mass. 02115, USA
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27
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Djavadian RL, Wielkopolska E, Turlejski K. Postnatal treatment with NAN-190 but not with 5-HT1A receptor agonists retards growth of the rat brain. Int J Dev Neurosci 2005; 23:485-93. [PMID: 16026684 DOI: 10.1016/j.ijdevneu.2005.02.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2004] [Revised: 01/27/2005] [Accepted: 02/23/2005] [Indexed: 10/25/2022] Open
Abstract
We investigated the influence of prolonged administration of the 5-HT1A receptor agonists (8-OH-DPAT or buspirone) or its antagonist, NAN-190 to rat pups on development of their cortical barrel field. Pups were injected daily with the drugs starting from the day of birth till either the 5th postnatal day or the 22-25th postnatal day and were perfused one day later. Square areas of their whisker barrel fields were measured on tangential sections of the cortex stained for cytochrome oxidase. Injections of 8-OH-DPAT or buspirone till the 5th postnatal day did not change any of the investigated parameters, while injections of NAN-190 resulted in 15% reduction of the pups' body and brain weight and proportional reduction of the square area of their barrel fields. Groups treated till the 22-25th postnatal day showed similar results. Some of these pups were injected with [C(14)]2-deoxyglucose to investigate the strength of responses of their cortical barrels to stimulation of corresponding vibrissae. The cortical area labeled with 2-deoxyglucose after stimulation of vibrissae of the row C was narrower in the NAN-190 injected rats. This functional deficit was more pronounced than the anatomical one, which resembled the effects of neonatal serotonin depletion (Neuroreport, 1997). Therefore, the results of injecting NAN-190 to the rat pups point to a deficit of trophic developmental influences of serotonin, adding new arguments for the hypothesis of a trophic role of 5-HT1A receptors in the brain development.
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Affiliation(s)
- R L Djavadian
- Nencki Institute of Experimental Biology, Laboratory of Neurobiology of Development and Evolution, 3 Pasteur Street, 02-093 Warsaw, Poland.
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28
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Esaki T, Cook M, Shimoji K, Murphy DL, Sokoloff L, Holmes A. Developmental disruption of serotonin transporter function impairs cerebral responses to whisker stimulation in mice. Proc Natl Acad Sci U S A 2005; 102:5582-7. [PMID: 15809439 PMCID: PMC556265 DOI: 10.1073/pnas.0501509102] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
There is growing evidence that serotonin (5-hydroxtryptamine, 5-HT) has major influences on brain development in mammals. Genetic and pharmacological disruption of 5-HT signaling during early postnatal development in rodents causes neuroanatomical cortical abnormalities, including malformations in the somatosensory cortex. Possible functional consequences of this developmental perturbation by 5-HT are not yet understood. We have examined the effects of deletion of the 5-HT transporter (5-HTT) gene on somatosensory responses to sensory stimulation in mice. Local cerebral glucose utilization (lCMR(glc)) was measured by the quantitative 2-deoxy[(14)C]glucose method during unilateral whisker stimulation in awake adult mice. lCMR(glc) was increased by stimulation but to a markedly lesser extent in 5-HTT(-/-) mice than in 5-HTT(+/+) controls in each of four major stations in the whisker-to-barrel cortex pathway (the spinal and principal sensory trigeminal nuclei, the ventral posteromedial thalamic nucleus, and the barrel region of the somatosensory cortex). Lowering brain 5-HT levels by administration of the selective tryptophan hydroxylase inhibitor p-chlorophenylalanine on postnatal days 0 and 1 restored the metabolic responses to functional activation in the whisker-to-barrel cortex pathway in adult 5-HTT(-/-) mice. These results indicate that functional deficits in this pathway in 5-HTT(-/-) mice may be due to excessive postnatal 5-HT activity. With or without postnatal p-chlorophenylalanine treatment, 5-HTT(-/-) mice exhibited lower resting (unstimulated) lCMR(glc) than did 5-HTT(+/+) controls in the whisker-to-barrel cortex pathway and throughout the brain. These findings have implications for understanding the potential long-term consequences of genetic and pharmacological disruption of 5-HT neurotransmission on cerebral functions during critical periods of postnatal development.
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Affiliation(s)
- Takanori Esaki
- Laboratory of Cerebral Metabolism, National Institute of Mental Health, Clinical Center, National Institutes of Health, Bethesda, MD 20892, USA
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Stanwood GD, Parlaman JP, Levitt P. Anatomical abnormalities in dopaminoceptive regions of the cerebral cortex of dopamine D1 receptor mutant mice. J Comp Neurol 2005; 487:270-82. [PMID: 15892099 DOI: 10.1002/cne.20548] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Alteration of dopamine neurotransmission during development can induce specific changes in neuronal structure and function. Here, we report specific morphological and neurochemical changes of projection neurons and interneurons of the medial frontal cortex of the dopamine D(1) receptor null mouse. Using immunostaining of cytoskeletal proteins and a crossbred D(1) receptor null:YFP transgenic reporter line, we demonstrate that the apical dendrites of pyramidal cells are abnormally organized in the prefrontal and anterior cingulate cortices of mice lacking the D(1) receptor. Neuronal processes exhibit a decrease in bundling and an increase in irregular, tortuous patterning as they weave a course towards the pial surface. In addition, there is increased parvalbumin staining of the dendrites of cortical interneurons in D(1) receptor null mice. Both pyramidal and interneuron alterations are evident by the early postnatal period and persist into adulthood. The alterations show regional specificity, in that dendritic profiles of projection neurons and interneurons in somatosensory and visual cortices develop normally. The abnormalities are reminiscent of those induced by prenatal exposure to cocaine in rabbits, an insult which has been shown to produce an attenuation of D(1) receptor-mediated responses through G(salpha). These results suggest that loss of D(1) receptor-mediated signaling during development produces permanent alterations in the cellular organization of specific cortical areas involved in attention, cognition, and emotion. Pharmacological and behavioral studies in the D(1) null mouse should be interpreted in the context of possible altered circuitry, given the presence of these developmental defects in the organization of dopaminoceptive regions of the cerebral cortex.
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Affiliation(s)
- Gregg D Stanwood
- Vanderbilt Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, Tennessee 37203, USA.
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Xu Y, Sari Y, Zhou FC. Selective serotonin reuptake inhibitor disrupts organization of thalamocortical somatosensory barrels during development. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 2004; 150:151-61. [PMID: 15158078 DOI: 10.1016/j.devbrainres.2003.02.001] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 02/18/2003] [Indexed: 10/26/2022]
Abstract
To further investigate the role of the transiently expressed serotonin (5-HT) transporter (5-HTT) in the development of thalamic fibers projecting to cortical barrels and the potential developmental changes in neuronal circuitry caused by a selective serotonin reuptake inhibitor (SSRI), paroxetine (5 mg/kg, twice daily, s.c.) or saline was administered to rat pups from postnatal day 0 (P0) to P8. Pups were perfused on P8 for 5-HT immunostaining (-im) to confirm the 5-HT uptake blockade, and 5-HTT-im and phospholipase C-beta1 (PLC-beta1)-im to label the thalamic afferents to barrels and barrel cells respectively. Paroxetine treatment completely blocked 5-HT uptake into the thalamocortical fibers as indicated by the negative 5-HT-im in cortical barrel areas. Organization of thalamic afferents to barrels, indicated by 5-HTT-im or PLC-beta1, was altered in paroxetine-treated pups in the following manners: (1) segregation of thalamocortical fibers was partially disrupted and thalamocortical fibers corresponding to anterior snouts and row A mystacial vibrissae were fused; (2) sizes of the unfused thalamocortical fiber patches related to the long caudal vibrissae in rows B, C, D and E were significantly decreased without changes in the brain weights and cortical areas representing these vibrissae; and (3) thalamocortical fibers corresponding to C4 and D4 vibrissae tended to be closer to each other along the arc while the relative positions of thalamocortical fibers related to the rest of the vibrissae were normal. Our study demonstrated that 5-HTT plays an important role in the refinement, but not the formation, of barrel-like clusters of thalamocortical fibers and that the development of neural circuitry in rodent somatosensory cortex was affected by exposure to a SSRI during thalamocortical synaptic formation.
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Affiliation(s)
- Yanling Xu
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, 635 Barnhill Drive, Indianapolis, IN 46202, USA
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Touri F, Welker E, Riederer BM. Differential distribution of MAP1A isoforms in the adult mouse barrel cortex and comparison with the serotonin 5-HT2A receptor. J Chem Neuroanat 2004; 27:99-108. [PMID: 15121214 DOI: 10.1016/j.jchemneu.2003.12.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2003] [Revised: 10/13/2003] [Accepted: 12/29/2003] [Indexed: 10/26/2022]
Abstract
Microtubule-associated protein 1A (MAP1A) is essential during the late differentiation phase of neuronal development. Here, we demonstrated the presence of two MAP1A isoforms with a differential spatial distribution in the adult mouse barrel cortex. Antibody A stained MAP1A in pyramidal and stellate cells, including dendrites that crossed layer IV in the septa between barrels. The other antibody, BW6 recognized a MAP1A isoform that was mainly confined to the barrel hollow and identified smaller caliber dendrites. Previously, an interaction of MAP1A and the serotonin 5-hydroxytryptamine 2A (5-HT(2A)) receptor was shown in the rat cortex. Here, we identified, by double-immunofluorescent labeling, MAP1A isoform and serotonin 5-HT(2A) receptor distribution. MAP1A co-localized mainly with 5-HT(2A) receptor in larger apical dendrites situated in septa. This differential staining of MAP1A and a serotonin receptor in defined barrel compartments may be due to changes in the expression or processing of MAP1A during dendritic transport as a consequence of functional differences in processing of whisker-related sensory input.
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Affiliation(s)
- F Touri
- Institut de Biologie Cellulaire et de Morphologie, Université de Lausanne, Rue du Bugnon 9, 1005 Lausanne, Switzerland
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Brown CE, Seif I, De Maeyer E, Dyck RH. Altered zincergic innervation of the developing primary somatosensory cortex in monoamine oxidase-A knockout mice. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 2003; 142:19-29. [PMID: 12694941 DOI: 10.1016/s0165-3806(03)00008-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Genetic inactivation of monoamine oxidase-A (MAO-A) significantly elevates levels of serotonin (5-HT) during early development and causes a disruption in the compartmented organization of thalamocortical axon terminals in layer 4 of the somatosensory cortex. In order to determine whether corticocortical innervation of the primary somatosensory cortex is also affected by this mutation, we examined the distribution of zinc-containing axon terminals (terminals known to originate from within the cortex) in the developing somatosensory cortex of MAO-A knockout mice, at postnatal days (PD) 3, 5, 6, 8, 10, 12, 15, 28, and 60. In layer 4 of wild-type mice, histochemical staining for zinc respected barrel-specific compartments at all ages beyond PD 5. By contrast, zinc staining in MAO-A knockout mice did not exhibit signs of barrel compartmentation at any age. Across cortical layers, substantial developmental changes in the distribution of zinc-containing terminals were observed in wild-type mice up until PD 12, at which time the mature lamina-specific pattern of zinc staining was achieved. Similar changes were observed in the somatosensory cortex of MAO-A knockout mice, except that its developmental time course was significantly compressed, with zincergic innervation achieving a mature appearance by PD 8. These results provide evidence that an excess of monoamines, most likely 5-HT, dramatically perturbs the columnar organization of intracortical zincergic afferents in layer 4 and significantly accelerates the appearance of a mature laminar pattern of zinc-containing corticocortical terminals.
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Affiliation(s)
- Craig E Brown
- Department of Psychology, University of Calgary, 2500 University Drive, NW, Calgary, Alberta T2N 1N4, Canada
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Alvarez C, Vitalis T, Fon EA, Hanoun N, Hamon M, Seif I, Edwards R, Gaspar P, Cases O. Effects of genetic depletion of monoamines on somatosensory cortical development. Neuroscience 2003; 115:753-64. [PMID: 12435414 DOI: 10.1016/s0306-4522(02)00484-0] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Raised levels of serotonin cause alterations in the development of the barrelfield of the primary somatosensory cortex (S1) in rodents. We examined the development of S1 in genetic mouse models in which the levels of serotonin and/or dopamine and noradrenaline are drastically reduced. Mice lacking the vesicular monoamine transporter type 2 (VMAT2 KO) are hypomorphic with rare pups surviving until postnatal day (P) 6. Serotonin, dopamine and noradrenaline are almost undetectable in the brain. In S1 we find that the segregation of thalamocortical axons into whisker patterns is delayed by 1 day and that layer IV granular neurons fail to form normal barrels. Moreover, the growth of cortical layers II-IV is reduced. Despite severe malnutrition, we show that these alterations are not caused by increased cell death in the thalamus or S1. Moreover, the maturation of cortical neurons is not altered as reflected by calcium-binding protein immunolabeling. Mice lacking both VMAT2 and monoamine oxidase type A (MAOA) were generated. VMAT2-MAOA DKO mice are hypomorphic but survive until P13. Increased levels of serotonin but profoundly reduced dopamine and noradrenaline levels are found in the brains. In S1, alterations are similar to those observed in MAOA KO mice: thalamocortical axons and granular neurons failed to form barrels. In addition there is a severe reduction in the thickness of the upper cortical layers as in the VMAT2 KO mice. These results show that monoamines have no instructive effect per se on the formation of thalamocortical patterning in S1. However, monoamines appear to be essential for the normal cytoarchitectonic maturation of the granular (IV) and supragranular cortical layers (II-III). Since developmental cell death and chemoarchitectonic differentiation of these neurons are not modified, it is possible that these alterations result from migration defects and/or from altered synaptic maturation.
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Affiliation(s)
- C Alvarez
- INSERM U106, IFR des Neurosciences, Bâtiment de Pédiatrie, Hôpital de la Pitié-Salpêtrière, 47 Boulevard de l'Hôpital, 75651 Paris Cedex 13, France
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Henkel CK, Fuentes-Santamaria V, Alvarado JC, Brunso-Bechtold JK. Quantitative measurement of afferent layers in the ferret inferior colliculus: DNLL projections to sublayers. Hear Res 2003; 177:32-42. [PMID: 12618315 DOI: 10.1016/s0378-5955(02)00794-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
In the central nucleus of the inferior colliculus (IC), afferent projections are aligned with dendritic arbors of disk-shaped cells, forming fibrodendritic layers. One feature that may serve as a guide for study of the intrinsic organization of the IC layers is the segregation of certain inputs to bands and patches within the layers of the central nucleus. In this study, we used Phaseolus leucoagglutinin as an anterograde tracer to examine the projections from the dorsal nucleus of the lateral lemniscus to the contralateral IC in adult ferrets. The labeled afferent projections distributed along the IC layers in a series of bands where there were dense endings and interband spaces where there were few if any endings. Branches of individual labeled axons that were reconstructed distributed within a single afferent band. Measurements of both the terminal density distribution and the optical density across the band were similar indicating that afferent bands were approximately 85 microm thick. Quantitative measurements of the labeled afferent bands will enhance comparison with other afferent projections and analysis of afferent development and plasticity.
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Affiliation(s)
- Craig K Henkel
- Department of Neurobiology and Anatomy, Wake Forest University School of Medicine,Winston-Salem, NC 27157, USA.
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Richards KS, Simon DJ, Pulver SR, Beltz BS, Marder E. Serotonin in the developing stomatogastric system of the lobster, Homarus americanus. JOURNAL OF NEUROBIOLOGY 2003; 54:380-92. [PMID: 12500313 DOI: 10.1002/neu.10136] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We studied the development of the serotonergic modulation of the stomatogastric nervous system of the lobster, Homarus americanus. Although the stomatogastric ganglion (STG) is present early in embryonic development, serotonin immunoreactivity is not visible in the STG until the second larval stage. However, incubation of the STG with exogenous serotonin showed that a serotonin transporter is present in embryonic and early larval stages. Serotonin uptake was blocked by paroxetine and 0% Na(+) saline. The presence of a serotonin transporter in the embryonic STG suggests that hormonally liberated serotonin could be taken up by the STG, and potentially released as a "borrowed transmitter". Consistent with a potential hormonal role, serotonin is found in the pericardial organs, a major neurosecretory structure, by midembryonic development. The rhythmic motor patterns produced by embryonic and larval STGs were decreased in frequency by serotonin. Lateral Pyloric (LP) neuron-evoked excitatory junctional potentials (EJPs) in the embryos and the first larval stage (LI) were larger, slower, and more variable than those in the adult. The amplitude of adult LP neuron-evoked EJPs was increased more than twofold in serotonin, but in embryos and LI preparations this effect was negligible. In embryos and LI preparations, serotonin increased the occurrence of muscle fiber action potentials and altered the EJP wave-form. These data demonstrate that serotonin receptors are present in the stomatogastric nervous system early in development, and suggest that the role of serotonin changes from modulation of muscle fiber excitability early in development to enhancement of neurally evoked EJPs in the adult.
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Affiliation(s)
- Kathryn S Richards
- Biology Department, Brandeis University, Waltham, Massachusetts 02454, USA
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Nishimura A, Hohmann CF, Johnston MV, Blue ME. Neonatal electrolytic lesions of the basal forebrain stunt plasticity in mouse barrel field cortex. Int J Dev Neurosci 2002; 20:481-9. [PMID: 12392751 DOI: 10.1016/s0736-5748(02)00078-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Previous studies have shown that neonatal electrolytic lesions of basal forebrain cholinergic projections in mice lead to a transient cholinergic depletion of neocortex and to permanent alterations in cortical cytoarchitecture and in cognitive performance. The present study examines whether neonatal electrolytic lesions of the basal forebrain modify neocortical plasticity. Using cytochrome oxidase histochemistry, we compared cross-sectional areas of individual barrels in the barrel field of four groups of postnatal day 8 (P8) old mice that on P1 received either (1) right electrolytic lesions of the basal forebrain, (2) left C row 1-4 whisker follicle ablations, (3) combined lesion treatments or (4) ice anesthesia only. The size of barrels in basal forebrain lesioned animals was not significantly different from controls. However, the plastic response to whisker removal was compromised in basal forebrain lesioned animals. An index of plasticity, the ratio of row D/row C areas, was reduced significantly in the combined nBM lesioned/follicle ablation group. Compared to whisker-lesioned mice, the expansion in rows B and D and the shrinkage in the lesioned row C area were diminished in the combined treatment group. The present findings correspond to those from a study of rats injected with a cholinergic immunotoxin [Cereb. Cortex 8 (1998) 63]. These results suggest that cholinergic inputs play a role in regulating plasticity as well as in the morphogenesis of mouse sensory-motor cortex.
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Affiliation(s)
- Akira Nishimura
- Neuroscience Laboratory, The Kennedy Krieger Research Institute, 707 North Broadway, Baltimore, MD 21205, USA
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Gutiérrez-Ospina G, Manjarrez-Gutiérrez G, González C, López S, Herrera R, Medina Aguirre I, Hernández-R J. Neither increased nor decreased availability of cortical serotonin (5HT) disturbs barrel field formation in isocaloric undernourished rat pups. Int J Dev Neurosci 2002; 20:497-501. [PMID: 12392753 DOI: 10.1016/s0736-5748(02)00058-8] [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: 11/21/2022] Open
Abstract
Serotonin (5HT) is expressed transiently in primary sensory areas of the rat neocortex during the establishment of the thalamo-cortical topography and somatotopy. The precise role of 5HT during the specification of neocortical areas is still uncertain. We evaluated the effects of increasing and decreasing cortical serotonin concentrations on the specification of the barrel cortex using a rat model of isocaloric undernutrition. This manipulation increases brain 5HT levels during brain development. Undernourished animals were also treated with p-clorophenylalanine; an inhibitor of 5HT synthesis. Barrels representing the head were readily seen at postnatal day 5 in control and p-clorophenylalanine treated rats. In contrast, undernourished rats treated or not with p-clorophenylalanine showed no barrels representing the head but until postnatal day 7. Chromatographic analyses demonstrated that the concentration of cortical 5HT increased by 50% in undernourished pups during barrel field formation. Control and undernourished animals treated with p-clorophenylalanine had a significant reduction (90%) of 5HT in the cortex. The overall geometry of the barrel field and of individual barrels was similar among animal groups. Our results support that 5HT plays a small role in triggering and timing barrel field somatotopy.
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Affiliation(s)
- Gabriel Gutiérrez-Ospina
- Department of Cell Biology and Physiology, Biomedical Research Institute, National Autonomous University of México, México, DF 04510, Mexico.
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Upton AL, Ravary A, Salichon N, Moessner R, Lesch KP, Hen R, Seif I, Gaspar P. Lack of 5-HT(1B) receptor and of serotonin transporter have different effects on the segregation of retinal axons in the lateral geniculate nucleus compared to the superior colliculus. Neuroscience 2002; 111:597-610. [PMID: 12031347 DOI: 10.1016/s0306-4522(01)00602-9] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We have shown previously that raised levels of serotonin (5-hydroxytryptamine or 5-HT) during development prevent retinal ganglion cell axons from segregating into eye-specific regions in their principal targets: the superior colliculus and the dorsal lateral geniculate nucleus. Possible mediators of 5-HT in this system include its plasma membrane transporter, which is transiently expressed by a sub-population of retinal ganglion cells, and the presynaptic 5-HT(1B) receptor carried on retinal ganglion cell axons. We analysed the retinal projections of 5-HT(1B) knockout (n=15), serotonin transporter knockout (n=14), serotonin transporter/5-HT(1B) double knockout (n=4) and monoamine oxidase A/5-HT(1B) double knockout (n=3) mice. In all four different knockout mice, the ipsilateral retinal projection to the superior colliculus was more diffuse and lost its characteristic patchy distribution. The alterations were most severe in the serotonin transporter knockout mice, where the ipsilateral retinal fibres covered the entire rostrocaudal and mediolateral extent of the superior colliculus, whereas in the 5-HT(1B) and double knockout mice, fibres retracted from the caudal and lateral superior colliculus. Abnormalities in the 5-HT(1B) knockout mice appeared only after postnatal day (P) 4. Treatment with parachlorophenylalanine (at P1-P12) to decrease serotonin levels caused an exuberance of the ipsilateral retinal fibres throughout the superior colliculus (n=9). In the dorsal lateral geniculate nucleus in contrast, the distribution and size of the ipsilateral retinal projection was normal in all four knockout mice. In the serotonin transporter knockout mice however, the contralateral retinal fibres failed to retract from the mediodorsal dorsal lateral geniculate nucleus, an abnormality that was reversed by early treatment with parachlorophenylalanine and in the serotonin transporter/5-HT(1B) double knockout. OUR OBSERVATIONS INDICATE: (1) that the lack of 5-HT transporter and the associated changes in 5-HT levels impair the segregation of retinal axons in both the superior colliculus and the dorsal lateral geniculate nucleus; (2) that 5-HT and 5-HT(1B) receptors are necessary for the normal refinement of the ipsilateral retinal fibres in the superior colliculus, but are not essential for the establishment of eye-specific segregation in the thalamus. Thus, both an excess and a lack of 5-HT affect the refinement of the superior colliculus retinal projection, while the establishment of eye-specific patterns in the dorsal lateral geniculate nucleus appears not to be sensitive to the lack of 5-HT or 5-HT(1B) receptors.
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Affiliation(s)
- A L Upton
- INSERM U106, Hôpital de la Pitié-Salpêtrière, Paris, France
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Zhu XO, de Permentier PJ, Waite PME. Cholinergic depletion by IgG192-saporin retards development of rat barrel cortex. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 2002; 136:1-16. [PMID: 12036512 DOI: 10.1016/s0165-3806(02)00301-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
This study examines the role of cholinergic projections from the basal forebrain on development of the rodent barrel cortex. Pups were administered the immunotoxin IgG192-saporin (0.1 microg) intraventricularly at postnatal day (P) 0 and sacrificed at P1-P7. One ventricle was injected with saporin while the other side received saline, allowing comparison between the two sides of the same animal, as well as with controls receiving saline only. Compared to control animals, neuronal loss in the basal forebrain was present on both sides of saporin-treated pups but was significantly greater on the toxin-treated side, in all age groups and regions sampled. Depletion of acetylcholine did not prevent the formation of the barrel pattern, however it delayed its emergence by approximately 1 day. At P4, the thickness of layer IV barrel cortex was also significantly reduced; this reduction was undetectable by P7. From P3 to P5, the ratios of intensity of staining for acetylcholinesterase between the barrel centres and septa on the toxin-treated side were significantly lower than those on the saline side, although normal densities were present by P7. Thus, the depletion of cholinergic innervation at birth causes a transient delay in the development of the barrel pattern during the first postnatal week.
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Affiliation(s)
- X O Zhu
- Department of Anatomy, University of New South Wales, NSW 2052, Sydney, Australia.
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Abstract
Serotonergic (5-HT) axons from the raphe nuclei are among the earliest afferents to innervate the developing forebrain. The present study examined whether GAP-43, a growth-associated protein expressed on growing 5-HT axons, is necessary for normal 5-HT axonal outgrowth and terminal arborization during the perinatal period. We found a nearly complete failure of 5-HT immunoreactive axons to innervate the cortex and hippocampus in GAP-43-null (GAP43-/-) mice. Abnormal ingrowth of 5-HT axons was apparent on postnatal day 0 (P0); quantitative analysis of P7 brains revealed significant reductions in the density of 5-HT axons in the cortex and hippocampus of GAP43-/- mice relative to wild-type (WT) controls. In contrast, 5-HT axon density was normal in the striatum, septum, and amygdala and dramatically higher than normal in the thalamus of GAP43-/- mice. Concentrations of serotonin and its metabolite, 5-hydroxyindolacetic acid, and norepinephrine were decreased markedly in the anterior and posterior cerebrum but increased in the brainstem of GAP43-/- mice. Cell loss could not account for these abnormalities, because unbiased stereological analysis showed no significant difference in the number of 5-HT dorsal raphe neurons in P7 GAP43-/- versus WT mice. The aberrant 5-HT innervation pattern persisted at P21, indicating a long-term alteration of 5-HT projections to forebrain in the absence of GAP-43. In heterozygotes, the density and morphology of 5-HT axons was intermediate between WT and homozygous GAP43-/- mice. These results suggest that GAP-43 is a key regulator in normal pathfinding and arborization of 5-HT axons during early brain development.
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Barrel pattern formation requires serotonin uptake by thalamocortical afferents, and not vesicular monoamine release. J Neurosci 2001. [PMID: 11517274 DOI: 10.1523/jneurosci.21-17-06862.2001] [Citation(s) in RCA: 156] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Thalamocortical neurons innervating the barrel cortex in neonatal rodents transiently store serotonin (5-HT) in synaptic vesicles by expressing the plasma membrane serotonin transporter (5-HTT) and the vesicular monoamine transporter (VMAT2). 5-HTT knock-out (ko) mice reveal a nearly complete absence of 5-HT in the cerebral cortex by immunohistochemistry, and of barrels, both at P7 and adulthood. Quantitative electron microscopy reveals that 5-HTT ko affects neither the density of synapses nor the length of synaptic contacts in layer IV. VMAT2 ko mice, completely lacking activity-dependent vesicular release of monoamines including 5-HT, also show a complete lack of 5-HT in the cortex but display largely normal barrel fields, despite sometimes markedly reduced postnatal growth. Transient 5-HTT expression is thus required for barrel pattern formation, whereas activity-dependent vesicular 5-HT release is not.
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Excessive activation of serotonin (5-HT) 1B receptors disrupts the formation of sensory maps in monoamine oxidase a and 5-ht transporter knock-out mice. J Neurosci 2001. [PMID: 11157075 DOI: 10.1523/jneurosci.21-03-00884.2001] [Citation(s) in RCA: 190] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Deficiency in the monoamine degradation enzyme monoamine oxidase A (MAOA) or prenatal exposure to the monoamine uptake inhibitor cocaine alters behavior in humans and rodents, but the mechanisms are unclear. In MAOA knock-out mice, inhibiting serotonin synthesis during development can prevent abnormal segregation of axons in the retinogeniculate and somatosensory thalamocortical systems. To investigate this effect, we crossed MAOA knock-outs with mice lacking the serotonin transporter 5-HTT or the 5-HT1B receptor, two molecules present in developing sensory projections. Segregation was abnormal in 5-HTT knock-outs and MAOA/5-HTT double knock-outs but was normalized in MAOA/5-HT1B double knock-outs and MAOA/5-HTT/5-HT1B triple knock-outs. This demonstrates that the 5-HT1B receptor is a key factor in abnormal segregation of sensory projections and suggests that serotonergic drugs represent a risk for the development of these projections. We also found that the 5-HT1B receptor has an adverse developmental impact on beam-walking behavior in MAOA knock-outs. Finally, because the 5-HT1B receptor inhibits glutamate release, our results suggest that visual and somatosensory projections must release glutamate for proper segregation.
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