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Gianni G, Pasqualetti M. Wiring and Volume Transmission: An Overview of the Dual Modality for Serotonin Neurotransmission. ACS Chem Neurosci 2023; 14:4093-4104. [PMID: 37966717 DOI: 10.1021/acschemneuro.3c00648] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2023] Open
Abstract
Serotonin is a neurotransmitter involved in the modulation of a multitude of physiological and behavioral processes. In spite of the relatively reduced number of serotonin-producing neurons present in the mammalian CNS, a complex long-range projection system provides profuse innervation to the whole brain. Heterogeneity of serotonin receptors, grouped in seven families, and their spatiotemporal expression pattern account for its widespread impact. Although neuronal communication occurs primarily at tiny gaps called synapses, wiring transmission, another mechanism based on extrasynaptic diffusion of neuroactive molecules and referred to as volume transmission, has been described. While wiring transmission is a rapid and specific one-to-one modality of communication, volume transmission is a broader and slower mode in which a single element can simultaneously act on several different targets in a one-to-many mode. Some experimental evidence regarding ultrastructural features, extrasynaptic localization of receptors and transporters, and serotonin-glia interactions collected over the past four decades supports the existence of a serotonergic system of a dual modality of neurotransmission, in which wiring and volume transmission coexist. To date, in spite of the radical difference in the two modalities, limited information is available on the way they are coordinated to mediate the specific activities in which serotonin participates. Understanding how wiring and volume transmission modalities contribute to serotonergic neurotransmission is of utmost relevance for the comprehension of serotonin functions in both physiological and pathological conditions.
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Affiliation(s)
- Giulia Gianni
- Unit of Cell and Developmental Biology, Department of Biology, University of Pisa, 56127 Pisa, Italy
| | - Massimo Pasqualetti
- Unit of Cell and Developmental Biology, Department of Biology, University of Pisa, 56127 Pisa, Italy
- Center for Neuroscience and Cognitive Systems @UniTn, Istituto Italiano di Tecnologia, 38068 Rovereto, Italy
- Centro per l'Integrazione della Strumentazione Scientifica dell'Università di Pisa (CISUP), 56126 Pisa, Italy
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2
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Fidalgo S, Yeoman MS. Age-Related Changes in Central Nervous System 5-Hydroxytryptamine Signalling and Its Potential Effects on the Regulation of Lifespan. Subcell Biochem 2023; 102:379-413. [PMID: 36600141 DOI: 10.1007/978-3-031-21410-3_15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Serotonin or 5-hydroxytryptamine (5-HT) is an important neurotransmitter in the central nervous system and the periphery. Most 5-HT (~99%) is found in the periphery where it regulates the function of the gastrointestinal (GI) tract and is an important regulator of platelet aggregation. However, the remaining 1% that is found in the central nervous system (CNS) can regulate a range of physiological processes such as learning and memory formation, mood, food intake, sleep, temperature and pain perception. More recent work on the CNS of invertebrate model systems has shown that 5-HT can directly regulate lifespan.This chapter will focus on detailing how CNS 5-HT signalling is altered with increasing age and the potential consequences this has on its ability to regulate lifespan.
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Affiliation(s)
| | - Mark S Yeoman
- Centre for Stress and Age-Related Disease, School of Applied Sciences, University of Brighton, Brighton, United Kingdom.
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3
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de Oliveira Figueiredo EC, Bondiolotti BM, Laugeray A, Bezzi P. Synaptic Plasticity Dysfunctions in the Pathophysiology of 22q11 Deletion Syndrome: Is There a Role for Astrocytes? Int J Mol Sci 2022; 23:ijms23084412. [PMID: 35457231 PMCID: PMC9028090 DOI: 10.3390/ijms23084412] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 04/14/2022] [Accepted: 04/15/2022] [Indexed: 01/01/2023] Open
Abstract
The 22q11 deletion syndrome (DS) is the most common microdeletion syndrome in humans and gives a high probability of developing psychiatric disorders. Synaptic and neuronal malfunctions appear to be at the core of the symptoms presented by patients. In fact, it has long been suggested that the behavioural and cognitive impairments observed in 22q11DS are probably due to alterations in the mechanisms regulating synaptic function and plasticity. Often, synaptic changes are related to structural and functional changes observed in patients with cognitive dysfunctions, therefore suggesting that synaptic plasticity has a crucial role in the pathophysiology of the syndrome. Most interestingly, among the genes deleted in 22q11DS, six encode for mitochondrial proteins that, in mouse models, are highly expressed just after birth, when active synaptogenesis occurs, therefore indicating that mitochondrial processes are strictly related to synapse formation and maintenance of a correct synaptic signalling. Because correct synaptic functioning, not only requires correct neuronal function and metabolism, but also needs the active contribution of astrocytes, we summarize in this review recent studies showing the involvement of synaptic plasticity in the pathophysiology of 22q11DS and we discuss the relevance of mitochondria in these processes and the possible involvement of astrocytes.
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Affiliation(s)
| | - Bianca Maria Bondiolotti
- Department of Fundamental Neurosciences, University of Lausanne, 1005 Lausanne, Switzerland; (E.C.d.O.F.); (B.M.B.); (A.L.)
| | - Anthony Laugeray
- Department of Fundamental Neurosciences, University of Lausanne, 1005 Lausanne, Switzerland; (E.C.d.O.F.); (B.M.B.); (A.L.)
| | - Paola Bezzi
- Department of Fundamental Neurosciences, University of Lausanne, 1005 Lausanne, Switzerland; (E.C.d.O.F.); (B.M.B.); (A.L.)
- Department of Pharmacology and Physiology, University of Rome Sapienza, 00185 Rome, Italy
- Correspondence: or
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4
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Koizumi S. Glial Purinergic Signals and Psychiatric Disorders. Front Cell Neurosci 2022; 15:822614. [PMID: 35069121 PMCID: PMC8766327 DOI: 10.3389/fncel.2021.822614] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 12/08/2021] [Indexed: 12/30/2022] Open
Abstract
Emotion-related neural networks are regulated in part by the activity of glial cells, and glial dysfunction can be directly related to emotional diseases such as depression. Here, we discuss three different therapeutic strategies involving astrocytes that are effective for treating depression. First, the antidepressant, fluoxetine, acts on astrocytes and increases exocytosis of ATP. This has therapeutic effects via brain-derived neurotrophic factor-dependent mechanisms. Second, electroconvulsive therapy is a well-known treatment for drug-resistant depression. Electroconvulsive therapy releases ATP from astrocytes to induce leukemia inhibitory factors and fibroblast growth factor 2, which leads to antidepressive actions. Finally, sleep deprivation therapy is well-known to cause antidepressive effects. Sleep deprivation also increases release of ATP, whose metabolite, adenosine, has antidepressive effects. These independent treatments share the same mechanism, i.e., ATP release from astrocytes, indicating an essential role of glial purinergic signals in the pathogenesis of depression.
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Affiliation(s)
- Schuichi Koizumi
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan
- GLIA Center, University of Yamanashi, Yamanashi, Japan
- *Correspondence: Schuichi Koizumi
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5
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Singer T, Ding S, Ding S. Astroglia Abnormalities in Post-stroke Mood Disorders. ADVANCES IN NEUROBIOLOGY 2021; 26:115-138. [PMID: 34888833 DOI: 10.1007/978-3-030-77375-5_6] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Stroke is the leading cause of human death and disability. After a stroke, many patients may have some physical disability, including difficulties in moving, speaking, and seeing, but patients may also exhibit changes in mood manifested by depression, anxiety, and cognitive changes which we call post-stroke mood disorders (PSMDs). Astrocytes are the most diverse and numerous glial cell type in the central nervous system (CNS). They provide structural, nutritional, and metabolic support to neurons and regulate synaptic activity under normal conditions. Astrocytes are also critically involved in focal ischemic stroke (FIS). They undergo many changes after FIS. These changes may affect acute neuronal death and brain damage as well as brain recovery and PSMD in the chronic phase after FIS. Studies using postmortem brain specimens and animal models of FIS suggest that astrocytes/reactive astrocytes are involved in PSMD. This chapter provides an overview of recent advances in the molecular base of astrocyte in PSMD. As astrocytes exhibit high plasticity after FIS, we suggest that targeting local astrocytes may be a promising strategy for PSMD therapy.
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Affiliation(s)
- Tracey Singer
- Dalton Cardiovascular Research Center, Columbia, MO, USA
| | - Sarah Ding
- Dalton Cardiovascular Research Center, Columbia, MO, USA
| | - Shinghua Ding
- Dalton Cardiovascular Research Center, Columbia, MO, USA.
- Department of Biomedical, Biological and Chemical Engineering, University of Missouri, Columbia, MO, USA.
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6
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Akther S, Hirase H. Assessment of astrocytes as a mediator of memory and learning in rodents. Glia 2021; 70:1484-1505. [PMID: 34582594 DOI: 10.1002/glia.24099] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 09/15/2021] [Accepted: 09/16/2021] [Indexed: 12/26/2022]
Abstract
The classical view of astrocytes is that they provide supportive functions for neurons, transporting metabolites and maintaining the homeostasis of the extracellular milieu. This view is gradually changing with the advent of molecular genetics and optical methods allowing interrogation of selected cell types in live experimental animals. An emerging view that astrocytes additionally act as a mediator of synaptic plasticity and contribute to learning processes has gained in vitro and in vivo experimental support. Here we focus on the literature published in the past two decades to review the roles of astrocytes in brain plasticity in rodents, whereby the roles of neurotransmitters and neuromodulators are considered to be comparable to those in humans. We outline established inputs and outputs of astrocytes and discuss how manipulations of astrocytes have impacted the behavior in various learning paradigms. Multiple studies suggest that the contribution of astrocytes has a considerably longer time course than neuronal activation, indicating metabolic roles of astrocytes. We advocate that exploring upstream and downstream mechanisms of astrocytic activation will further provide insight into brain plasticity and memory/learning impairment.
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Affiliation(s)
- Sonam Akther
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Hajime Hirase
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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7
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Roosterman D, Cottrell GS. The two-cell model of glucose metabolism: a hypothesis of schizophrenia. Mol Psychiatry 2021; 26:1738-1747. [PMID: 33402704 PMCID: PMC8440173 DOI: 10.1038/s41380-020-00980-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Revised: 11/16/2020] [Accepted: 12/01/2020] [Indexed: 02/07/2023]
Abstract
Schizophrenia is a chronic and severe mental disorder that affects over 20 million people worldwide. Common symptoms include distortions in thinking, perception, emotions, language, and self awareness. Different hypotheses have been proposed to explain the development of schizophrenia, however, there are no unifying features between the proposed hypotheses. Schizophrenic patients have perturbed levels of glucose in their cerebrospinal fluid, indicating a disturbance in glucose metabolism. We have explored the possibility that disturbances in glucose metabolism can be a general mechanism for predisposition and manifestation of the disease. We discuss glucose metabolism as a network of signaling pathways. Glucose and glucose metabolites can have diverse actions as signaling molecules, such as regulation of transcription factors, hormone and cytokine secretion and activation of neuronal cells, such as microglia. The presented model challenges well-established concepts in enzyme kinetics and glucose metabolism. We have developed a 'two-cell' model of glucose metabolism, which can explain the effects of electroconvulsive therapy and the beneficial and side effects of olanzapine treatment. Arrangement of glycolytic enzymes into metabolic signaling complexes within the 'two hit' hypothesis, allows schizophrenia to be formulated in two steps. The 'first hit' is the dysregulation of the glucose signaling pathway. This dysregulation of glucose metabolism primes the central nervous system for a pathological response to a 'second hit' via the astrocytic glycogenolysis signaling pathway.
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Affiliation(s)
- Dirk Roosterman
- Ruhr Universität Bochum, LWL-Hospital of Psychiatry, Bochum, Germany.
| | - Graeme Stuart Cottrell
- grid.9435.b0000 0004 0457 9566School of Pharmacy, University of Reading, Reading, RG6 6AP UK
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8
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Trait Anxiety Mediated by Amygdala Serotonin Transporter in the Common Marmoset. J Neurosci 2020; 40:4739-4749. [PMID: 32393533 DOI: 10.1523/jneurosci.2930-19.2020] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 03/06/2020] [Accepted: 03/19/2020] [Indexed: 01/04/2023] Open
Abstract
High trait anxiety is associated with altered activity across emotion regulation circuitry and a higher risk of developing anxiety disorders and depression. This circuitry is extensively modulated by serotonin. Here, to understand why some people may be more vulnerable to developing affective disorders, we investigated whether serotonin-related gene expression across the brain's emotion regulation circuitry may underlie individual differences in trait anxiety using the common marmoset (Callithrix jacchus, mixed sexes) as a model. First, we assessed the association of region-specific expression of the serotonin transporter (SLC6A4) and serotonin receptor (HTR1A, HTR2A, HTR2C) genes with anxiety-like behavior; and second, we investigated their causal role in two key features of the high trait anxious phenotype: high responsivity to anxiety-provoking stimuli and an exaggerated conditioned threat response. While the expression of the serotonin receptors did not show a significant relationship with anxiety-like behavior in any of the targeted brain regions, serotonin transporter expression, specifically within the right ventrolateral prefrontal cortex (vlPFC) and most strongly in the right amygdala, was associated positively with anxiety-like behavior. The causal relationship between amygdala serotonin levels and an animal's sensitivity to threat was confirmed via direct amygdala infusions of a selective serotonin reuptake inhibitor (SSRI), citalopram. Both anxiety-like behaviors, and conditioned threat-induced responses were reduced by the blockade of serotonin reuptake in the amygdala. Together, these findings provide evidence that high amygdala serotonin transporter expression contributes to the high trait anxious phenotype and suggest that reduction of threat reactivity by SSRIs may be mediated by their actions in the amygdala.SIGNIFICANCE STATEMENT Findings here contribute to our understanding of how the serotonin system underlies an individual's expression of threat-elicited negative emotions such as anxiety and fear within nonhuman primates. Exploration of serotonergic gene expression across brain regions implicated in emotion regulation revealed that serotonin transporter gene expression in the ventrolateral prefrontal cortex (vlPFC) and most strongly in the amygdala, but none of the serotonin receptor genes, were predictive of interindividual differences in anxiety-like behavior. Targeting of amygdala serotonin reuptake with selective serotonin reuptake inhibitors (SSRIs) confirmed the causal relationship between amygdala serotonin transporter and an animal's sensitivity to threat by reversing expression of two key features of the high trait-like anxiety phenotype: high responsivity to anxiety-provoking uncertain threat and responsivity to certain conditioned threat.
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9
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Paredes S, Cantillo S, Candido KD, Knezevic NN. An Association of Serotonin with Pain Disorders and Its Modulation by Estrogens. Int J Mol Sci 2019; 20:E5729. [PMID: 31731606 PMCID: PMC6888666 DOI: 10.3390/ijms20225729] [Citation(s) in RCA: 73] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Revised: 11/12/2019] [Accepted: 11/14/2019] [Indexed: 12/12/2022] Open
Abstract
Ovarian hormones play an important role in pain perception, and are responsible, at least in part, for the pain threshold differences between the sexes. Modulation of pain and its perception are mediated by neurochemical changes in several pathways, affecting both the central and peripheral nervous systems. One of the most studied neurotransmitters related to pain disorders is serotonin. Estrogen can modify serotonin synthesis and metabolism, promoting a general increase in its tonic effects. Studies evaluating the relationship between serotonin and disorders such as irritable bowel syndrome, fibromyalgia, migraine, and other types of headache suggest a clear impact of this neurotransmitter, thereby increasing the interest in serotonin as a possible future therapeutic target. This literature review describes the importance of substances such as serotonin and ovarian hormones in pain perception and illustrates the relationship between those two, and their direct influence on the presentation of the aforementioned pain-related conditions. Additionally, we review the pathways and receptors implicated in each disorder. Finally, the objective was to stimulate future pharmacological research to experimentally evaluate the potential of serotonin modulators and ovarian hormones as therapeutic agents to regulate pain in specific subpopulations.
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Affiliation(s)
- Stephania Paredes
- Department of Anesthesiology, Advocate Illinois Masonic Medical Center, 836 W. Wellington Ave. Suite 4815, Chicago, IL 60657, USA; (S.P.); (S.C.); (K.D.C.)
| | - Santiago Cantillo
- Department of Anesthesiology, Advocate Illinois Masonic Medical Center, 836 W. Wellington Ave. Suite 4815, Chicago, IL 60657, USA; (S.P.); (S.C.); (K.D.C.)
| | - Kenneth D. Candido
- Department of Anesthesiology, Advocate Illinois Masonic Medical Center, 836 W. Wellington Ave. Suite 4815, Chicago, IL 60657, USA; (S.P.); (S.C.); (K.D.C.)
- Department of Anesthesiology, University of Illinois, Chicago, IL 60612, USA
- Department of Surgery, University of Illinois, Chicago, IL 60612, USA
| | - Nebojsa Nick Knezevic
- Department of Anesthesiology, Advocate Illinois Masonic Medical Center, 836 W. Wellington Ave. Suite 4815, Chicago, IL 60657, USA; (S.P.); (S.C.); (K.D.C.)
- Department of Anesthesiology, University of Illinois, Chicago, IL 60612, USA
- Department of Surgery, University of Illinois, Chicago, IL 60612, USA
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10
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Garbarino VR, Gilman TL, Daws LC, Gould GG. Extreme enhancement or depletion of serotonin transporter function and serotonin availability in autism spectrum disorder. Pharmacol Res 2019; 140:85-99. [PMID: 30009933 PMCID: PMC6345621 DOI: 10.1016/j.phrs.2018.07.010] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 06/22/2018] [Accepted: 07/12/2018] [Indexed: 12/15/2022]
Abstract
A variety of human and animal studies support the hypothesis that serotonin (5-hydroxytryptamine or 5-HT) system dysfunction is a contributing factor to the development of autism in some patients. However, many questions remain about how developmental manipulation of various components that influence 5-HT signaling (5-HT synthesis, transport, metabolism) persistently impair social behaviors. This review will summarize key aspects of central 5-HT function important for normal brain development, and review evidence implicating perinatal disruptions in 5-HT signaling in the pathophysiology of autism spectrum disorder. We discuss the importance, and relative dearth, of studies that explore the possible correlation to autism in the interactions between important intrinsic and extrinsic factors that may disrupt 5-HT homeostasis during development. In particular, we focus on exposure to 5-HT transport altering mechanisms such as selective serotonin-reuptake inhibitors or genetic polymorphisms in primary or auxiliary transporters of 5-HT, and how they relate to neurological stores of serotonin and its precursors. A deeper understanding of the many mechanisms by which 5-HT signaling can be disrupted, alone and in concert, may contribute to an improved understanding of the etiologies and heterogeneous nature of this disorder. We postulate that extreme bidirectional perturbations of these factors during development likely compound or synergize to facilitate enduring neurochemical changes resulting in insufficient or excessive 5-HT signaling, that could underlie the persistent behavioral characteristics of autism spectrum disorder.
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Affiliation(s)
- Valentina R Garbarino
- Department of Cellular and Integrative Physiology, United States; The Sam and Ann Barshop Institute for Longevity and Aging Studies, United States.
| | - T Lee Gilman
- Department of Cellular and Integrative Physiology, United States; Addiction Research, Treatment & Training Center of Excellence, United States.
| | - Lynette C Daws
- Department of Cellular and Integrative Physiology, United States; Addiction Research, Treatment & Training Center of Excellence, United States; Department of Pharmacology, United States.
| | - Georgianna G Gould
- Department of Cellular and Integrative Physiology, United States; Center for Biomedical Neuroscience, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA.
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11
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Marathe SV, D'almeida PL, Virmani G, Bathini P, Alberi L. Effects of Monoamines and Antidepressants on Astrocyte Physiology: Implications for Monoamine Hypothesis of Depression. J Exp Neurosci 2018; 12:1179069518789149. [PMID: 30046253 PMCID: PMC6056786 DOI: 10.1177/1179069518789149] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Accepted: 06/19/2018] [Indexed: 01/17/2023] Open
Abstract
Major depressive disorder (MDD) is one of the most common neuropsychiatric
disorders affecting over one-fifth of the population worldwide. Owing to our
limited understanding of the pathophysiology of MDD, the quest for finding novel
antidepressant drug targets is severely impeded. Monoamine hypothesis of MDD
provides a robust theoretical framework, forming the core of a large jigsaw
puzzle, around which we must look for the vital missing pieces. Growing evidence
suggests that the glial loss observed in key regions of the limbic system in
depressed patients, at least partly, accounts for the structural and cognitive
manifestations of MDD. Studies in animal models have subsequently hinted at the
possibility that the glial atrophy may play a causative role in the
precipitation of depressive symptoms. Antidepressants as well as monoamine
neurotransmitters exert profound effects on the gene expression and metabolism
in astrocytes. This raises an intriguing possibility that the astrocytes may
play a central role alongside neurons in the behavioral effects of
antidepressant drugs. In this article, we discuss the gene expression and
metabolic changes brought about by antidepressants in astrocytes, which could be
of relevance to synaptic plasticity and behavioral effects of antidepressant
treatments.
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Affiliation(s)
| | | | - Garima Virmani
- Centre for Neuroscience, Indian Institute of Science, Bangalore, India
| | - Praveen Bathini
- Department of Medicine University of Fribourg, Fribourg, Switzerland.,Swiss Integrative Center for Human Health SA (SICHH), Fribourg, Switzerland
| | - Lavinia Alberi
- Department of Medicine University of Fribourg, Fribourg, Switzerland.,Swiss Integrative Center for Human Health SA (SICHH), Fribourg, Switzerland
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12
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Noda M, Ifuku M, Hossain MS, Katafuchi T. Glial Activation and Expression of the Serotonin Transporter in Chronic Fatigue Syndrome. Front Psychiatry 2018; 9:589. [PMID: 30505285 PMCID: PMC6250825 DOI: 10.3389/fpsyt.2018.00589] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2018] [Accepted: 10/25/2018] [Indexed: 12/19/2022] Open
Abstract
Fatigue is commonly reported in a variety of illnesses and has major impact on quality of life. Chronic fatigue syndrome (CFS) is a debilitating syndrome of unknown etiology. The clinical symptoms include problems in neuroendocrine, autonomic, and immune systems. It is becoming clear that the brain is the central regulator of CFS. For example, neuroinflammation, especially induced by activation of microglia and astrocytes, may play a prominent role in the development of CFS, though little is known about molecular mechanisms. Many possible causes of CFS have been proposed. However, in this mini-review, we summarize evidence for a role for microglia and astrocytes in the onset and the maintenance of immunologically induced CFS. In a model using virus mimicking synthetic double-stranded RNA, infection causes sequential signaling such as increased blood brain barrier (BBB) permeability, microglia/macrophage activation through Toll-like receptor 3 (TLR3) signaling, secretion of IL-1β, upregulation of the serotonin transporter (5-HTT) in astrocytes, reducing extracellular serotonin (5-HT) levels and hence reduced activation of 5-HT1A receptor subtype. Hopefully, drug discovery targeting these pathways may be effective for CFS therapy.
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Affiliation(s)
- Mami Noda
- Laboratory of Pathophysiology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
| | - Masataka Ifuku
- Department of Neuroinflammation and Brain Fatigue Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Md Shamim Hossain
- Department of Neuroinflammation and Brain Fatigue Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Toshihiko Katafuchi
- Department of Neuroinflammation and Brain Fatigue Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
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13
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Higuchi Y, Soga T, Parhar IS. Regulatory Pathways of Monoamine Oxidase A during Social Stress. Front Neurosci 2017; 11:604. [PMID: 29163009 PMCID: PMC5671571 DOI: 10.3389/fnins.2017.00604] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 10/16/2017] [Indexed: 12/18/2022] Open
Abstract
Social stress has a high impact on many biological systems in the brain, including serotonergic (5-HT) system-a major drug target in the current treatment for depression. Hyperactivity of hypothalamic-pituitary-adrenal (HPA) axis and monoamine oxidase A (MAO-A) are well-known stress responses, which are involved in the central 5-HT system. Although, many MAO-A inhibitors have been developed and used in the therapeutics of depression, effective management of depression by modulating the activity of MAO-A has not been achieved. Identifying the molecular pathways that regulate the activity of MAO-A in the brain is crucial for developing new drug targets for precise control of MAO-A activity. Over the last few decades, several regulatory pathways of MAO-A consisting of Kruppel like factor 11 (KLF11), Sirtuin1, Ring finger protein in neural stem cells (RINES), and Cell division cycle associated 7-like protein (R1) have been identified, and the influence of social stress on these regulatory factors evaluated. This review explores various aspects of these pathways to expand our understanding of the roles of the HPA axis and MAO-A regulatory pathways during social stress. The first part of this review introduces some components of the HPA axis, explains how stress affects them and how they interact with the 5-HT system in the brain. The second part summarizes the novel regulatory pathways of MAO-A, which have high potential as novel therapeutic targets for depression.
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Affiliation(s)
- Yuki Higuchi
- Brain Research Institute, School of Medicine and Health Sciences, Monash University Malaysia, Bandar Sunway, Malaysia
| | - Tomoko Soga
- Brain Research Institute, School of Medicine and Health Sciences, Monash University Malaysia, Bandar Sunway, Malaysia
| | - Ishwar S Parhar
- Brain Research Institute, School of Medicine and Health Sciences, Monash University Malaysia, Bandar Sunway, Malaysia
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14
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Astrocytic transporters in Alzheimer's disease. Biochem J 2017; 474:333-355. [DOI: 10.1042/bcj20160505] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 11/16/2016] [Accepted: 11/29/2016] [Indexed: 12/26/2022]
Abstract
Astrocytes play a fundamental role in maintaining the health and function of the central nervous system. Increasing evidence indicates that astrocytes undergo both cellular and molecular changes at an early stage in neurological diseases, including Alzheimer's disease (AD). These changes may reflect a change from a neuroprotective to a neurotoxic phenotype. Given the lack of current disease-modifying therapies for AD, astrocytes have become an interesting and viable target for therapeutic intervention. The astrocyte transport system covers a diverse array of proteins involved in metabolic support, neurotransmission and synaptic architecture. Therefore, specific targeting of individual transporter families has the potential to suppress neurodegeneration, a characteristic hallmark of AD. A small number of the 400 transporter superfamilies are expressed in astrocytes, with evidence highlighting a fraction of these are implicated in AD. Here, we review the current evidence for six astrocytic transporter subfamilies involved in AD, as reported in both animal and human studies. This review confirms that astrocytes are indeed a viable target, highlights the complexities of studying astrocytes and provides future directives to exploit the potential of astrocytes in tackling AD.
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15
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Zoratto F, Romano E, Pascale E, Pucci M, Falconi A, Dell'Osso B, Maccarrone M, Laviola G, D'Addario C, Adriani W. Down-regulation of serotonin and dopamine transporter genes in individual rats expressing a gambling-prone profile: A possible role for epigenetic mechanisms. Neuroscience 2016; 340:101-116. [PMID: 27789384 DOI: 10.1016/j.neuroscience.2016.10.041] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Revised: 10/12/2016] [Accepted: 10/17/2016] [Indexed: 11/26/2022]
Abstract
Gambling Disorder (GD) is characterized by excessive gambling despite adverse consequences on individual functioning. In spite of some positive findings, it is difficult to draw any conclusion on the genetics of GD. Indeed, beyond DNA sequence variation, other regulatory mechanisms (like those that engage epigenetics) may explain gene alterations in this addictive disease. Wistar male rats underwent an operant task for the evaluation of individual propensity to gamble. Few rats, after having learnt to prefer nose-poking for a large over a small food reward, were sacrificed to obtain a baseline profile of gene expression at both central and peripheral levels. In the remaining rats, probability of occurrence of large-reward delivery decreased progressively to very low levels. Thus, rats were faced with temptation to "gamble", i.e. to nose-poke for a binge reward, whose delivery was omitted the majority of times. After 3weeks of testing, rats showing a clear-cut profile of either gambling proneness or aversion were selected and sacrificed after the last session. A selective down-regulation of i) serotonin transporter in prefrontal cortex, ii) tyrosine hydroxylase in ventral striatum, iii) dopamine transporter in lymphocytes was evidenced in "gambler" vs "non-gambler" rats. The exposure to such operant task (compared to home-cage alone) modulated ventrostriatal but not prefrontal genes. A consistent increase of DNA methylation, in one specific CpG site at serotonin transporter gene, was evident in prefrontal cortex of "gambler" rats. Elucidation of epigenetic changes occurring during GD progression may pave the way to the development of new therapeutic strategies through specific modulation of epigenetic factors.
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Affiliation(s)
- Francesca Zoratto
- Department of Cell Biology and Neurosciences, Istituto Superiore di Sanità, Rome, Italy
| | - Emilia Romano
- Department of Cell Biology and Neurosciences, Istituto Superiore di Sanità, Rome, Italy
| | - Esterina Pascale
- Department of Medical Surgical Sciences & Biotechnology, "Sapienza" University of Rome, Rome, Italy
| | - Mariangela Pucci
- Faculty of Bioscience and Technology for Food, Agriculture and Environment, University of Teramo, Teramo, Italy
| | - Anastasia Falconi
- Faculty of Bioscience and Technology for Food, Agriculture and Environment, University of Teramo, Teramo, Italy
| | - Bernardo Dell'Osso
- Department of Pathophysiology and Transplantation, University of Milan, Fondazione IRCCS Ca' Granda Policlinico, Milan, Italy; Bipolar Disorders Clinic, Stanford University, Stanford, CA, USA
| | - Mauro Maccarrone
- School of Medicine and Department of Medicine, Campus Bio-Medico University of Rome, Rome, Italy; European Center for Brain Research, Santa Lucia Foundation, Rome, Italy
| | - Giovanni Laviola
- Department of Cell Biology and Neurosciences, Istituto Superiore di Sanità, Rome, Italy
| | - Claudio D'Addario
- Faculty of Bioscience and Technology for Food, Agriculture and Environment, University of Teramo, Teramo, Italy; Department of Clinical Neuroscience, Karolinska Institute, Stockholm, Sweden.
| | - Walter Adriani
- Department of Cell Biology and Neurosciences, Istituto Superiore di Sanità, Rome, Italy.
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16
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Park S, Nevin ABC, Cardozo-Pelaez F, Lurie DI. Pb exposure prolongs the time period for postnatal transient uptake of 5-HT by murine LSO neurons. Neurotoxicology 2016; 57:258-269. [PMID: 27771255 DOI: 10.1016/j.neuro.2016.10.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 09/27/2016] [Accepted: 10/17/2016] [Indexed: 01/09/2023]
Abstract
Pb exposure is associated with cognitive deficits including Attention Deficit Hyperactivity Disorder (ADHD) in children and alters auditory temporal processing in humans and animals. Serotonin has been implicated in auditory temporal processing and previous studies from our laboratory have demonstrated that developmental Pb decreases expression of serotonin (5-HT) in the adult murine lateral superior olive (LSO). During development, certain non-serotonergic sensory neurons, including auditory LSO neurons, transiently take up 5-HT through the serotonin reuptake transporter (SERT). The uptake of 5-HT is important for development of sensory systems. This study examines the effect of Pb on the serotonergic system in the LSO of the early postnatal mouse. Mice were exposed to moderate Pb (0.01mM) or high Pb (0.1mM) throughout gestation and postnatal day 4 (P4) and P8. We found that Pb exposure prolongs the normal developmental expression of 5-HT by LSO neurons and this is correlated with expression of SERT on LSO cell bodies. The prolonged expression of 5-HT by postnatal LSO neurons is correlated with decreased synaptic immunolabeling within the LSO. This Pb-associated decrease in synaptic density within the LSO could contribute to the auditory temporal processing deficits and cognitive deficits associated with developmental Pb exposure.
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Affiliation(s)
- Sunyoung Park
- Center for Structural and Functional Neuroscience, Center for Environmental Health Sciences, Department of Biomedical & Pharmaceutical Sciences, College of Health Professions and Biomedical Sciences, The University of Montana, Missoula, MT 59812, United States; Business Planning Department, Kyowa Hakko Kirin Korea Co., Ltd., Seoul, Republic of Korea
| | - Andrew B C Nevin
- Center for Structural and Functional Neuroscience, Center for Environmental Health Sciences, Department of Biomedical & Pharmaceutical Sciences, College of Health Professions and Biomedical Sciences, The University of Montana, Missoula, MT 59812, United States
| | - Fernando Cardozo-Pelaez
- Center for Structural and Functional Neuroscience, Center for Environmental Health Sciences, Department of Biomedical & Pharmaceutical Sciences, College of Health Professions and Biomedical Sciences, The University of Montana, Missoula, MT 59812, United States
| | - Diana I Lurie
- Center for Structural and Functional Neuroscience, Center for Environmental Health Sciences, Department of Biomedical & Pharmaceutical Sciences, College of Health Professions and Biomedical Sciences, The University of Montana, Missoula, MT 59812, United States.
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17
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Melendez RI, Roman C, Capo-Velez CM, Lasalde-Dominicci JA. Decreased glial and synaptic glutamate uptake in the striatum of HIV-1 gp120 transgenic mice. J Neurovirol 2015; 22:358-65. [PMID: 26567011 DOI: 10.1007/s13365-015-0403-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Revised: 10/27/2015] [Accepted: 10/30/2015] [Indexed: 12/22/2022]
Abstract
The mechanisms leading to the neurocognitive deficits in humans with immunodeficiency virus type 1 (HIV-1) are not well resolved. A number of cell culture models have demonstrated that the HIV-envelope glycoprotein 120 (gp120) decreases the reuptake of glutamate, which is necessary for learning, memory, and synaptic plasticity. However, the impact of brain HIV-1 gp120 on glutamate uptake systems in vivo remains unknown. Notably, alterations in brain glutamate uptake systems are implicated in a number of neurodegenerative and neurocognitive disorders. We characterized the kinetic properties of system XAG (sodium-dependent) and systems xc- (sodium-independent) [3H]-L-glutamate uptake in the striatum and hippocampus of HIV-1 gp120 transgenic mice, an established model of HIV neuropathology. We determined the kinetic constant Vmax (maximal velocity) and Km (affinity) of both systems XAG and xc- using subcellular preparations derived from neurons and glial cells. We show significant (30-35 %) reductions in the Vmax of systems XAG and xc- in both neuronal and glial preparations derived from the striatum, but not from the hippocampus of gp120 mice relative to wild-type (WT) controls. Moreover, immunoblot analysis showed that the protein expression of glutamate transporter subtype-1 (GLT-1), the predominant brain glutamate transporter, was significantly reduced in the striatum but not in the hippocampus of gp120 mice. These extensive and region-specific deficits of glutamate uptake likely contribute to the development and/or severity of HIV-associated neurocognitive disorders. Understanding the role of striatal glutamate uptake systems in HIV-1 gp120 may advance the development of new therapeutic strategies to prevent neuronal damage and improve cognitive function in HIV patients.
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Affiliation(s)
- Roberto I Melendez
- Department of Anatomy and Neurobiology, University of Puerto Rico, Medical Sciences Campus, Office #A-527, San Juan, 00936, Puerto Rico.
| | - Cristina Roman
- Department of Anatomy and Neurobiology, University of Puerto Rico, Medical Sciences Campus, Office #A-527, San Juan, 00936, Puerto Rico
| | - Coral M Capo-Velez
- Department of Biology, University of Puerto Rico, Rio Piedras, PR, 00936, USA
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18
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Henkel A, Alali H, Devassy A, Alawadi M, Redzic Z. Antagonistic interactions between dexamethasone and fluoxetine modulate morphodynamics and expression of cytokines in astrocytes. Neuroscience 2014; 280:318-27. [DOI: 10.1016/j.neuroscience.2014.09.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Revised: 09/04/2014] [Accepted: 09/07/2014] [Indexed: 12/27/2022]
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19
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Ifuku M, Hossain SM, Noda M, Katafuchi T. Induction of interleukin-1β by activated microglia is a prerequisite for immunologically induced fatigue. Eur J Neurosci 2014; 40:3253-63. [PMID: 25040499 DOI: 10.1111/ejn.12668] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2014] [Revised: 06/10/2014] [Accepted: 06/10/2014] [Indexed: 02/02/2023]
Abstract
We previously reported that an intraperitoneal (i.p.) injection of synthetic double-stranded RNA, polyriboinosinic:polyribocytidylic acid (poly-I:C), produced prolonged fatigue in rats, which might serve as a model for chronic fatigue syndrome. The poly-I:C-induced fatigue was associated with serotonin transporter (5-HTT) overexpression in the prefrontal cortex (PFC), a brain region that has been suggested to be critical for fatigue sensation. In the present study, we demonstrated that microglial activation in the PFC was important for poly-I:C-induced fatigue in rats, as pretreatment with minocycline, an inhibitor of microglial activation, prevented the decrease in running wheel activity. Poly-I:C injection increased the microglial interleukin (IL)-1β expression in the PFC. An intracerebroventricular (i.c.v.) injection of IL-1β neutralising antibody limited the poly-I:C-induced decrease in activity, whereas IL-1β (i.c.v.) reduced the activity in a dose-dependent manner. 5-HTT expression was enhanced by IL-1β in primary cultured astrocytes but not in microglia. Poly-I:C injection (i.p.) caused an increase in 5-HTT expression in astrocytes in the PFC of the rat, which was inhibited by pretreatment with minocycline (i.p.) and rat recombinant IL-1 receptor antagonist (i.c.v.). Poly-I:C injection (i.p.) led to a breakdown of the blood-brain barrier and enhanced Toll-like receptor 3 signaling in the brain. Furthermore, direct application of poly-I:C enhanced IL-1β expression in primary microglia. We therefore propose that poly-I:C-induced microglial activation, which may be at least partly caused by a direct action of poly-I:C, enhances IL-1β expression. Then, IL-1β induces 5-HTT expression in astrocytes, resulting in the immunologically induced fatigue.
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Affiliation(s)
- Masataka Ifuku
- Department of Integrative Physiology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan
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20
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Naganuma F, Yoshikawa T, Nakamura T, Iida T, Harada R, Mohsen AS, Miura Y, Yanai K. Predominant role of plasma membrane monoamine transporters in monoamine transport in 1321N1, a human astrocytoma-derived cell line. J Neurochem 2014; 129:591-601. [PMID: 24471494 DOI: 10.1111/jnc.12665] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Revised: 12/24/2013] [Accepted: 01/20/2014] [Indexed: 01/11/2023]
Abstract
Monoamine neurotransmitters should be immediately removed from the synaptic cleft to avoid excessive neuronal activity. Recent studies have shown that astrocytes and neurons are involved in monoamine removal. However, the mechanism of monoamine transport by astrocytes is not entirely clear. We aimed to elucidate the transporters responsible for monoamine transport in 1321N1, a human astrocytoma-derived cell line. First, we confirmed that 1321N1 cells transported dopamine, serotonin, norepinephrine, and histamine in a time- and dose-dependent manner. Kinetics analysis suggested the involvement of low-affinity monoamine transporters, such as organic cation transporter (OCT) 2 and 3 and plasma membrane monoamine transporter (PMAT). Monoamine transport in 1321N1 cells was not Na(+) /Cl(-) dependent but was inhibited by decynium-22, an inhibitor of low-affinity monoamine transporters, which supported the importance of low-affinity transporters. RT-PCR assays revealed that 1321N1 cells expressed OCT3 and PMAT but no other neurotransmitter transporters. Another human astrocytoma-derived cell line, U251MG, and primary human astrocytes also exhibited the same gene expression pattern. Gene-knockdown assays revealed that 1321N1 and primary human astrocytes could transport monoamines predominantly through PMAT and partly through OCT3. These results might indicate that PMAT and OCT3 in human astrocytes are involved in monoamine clearance.
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Affiliation(s)
- Fumito Naganuma
- Department of Pharmacology, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan
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21
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Rajkowska G, Stockmeier CA. Astrocyte pathology in major depressive disorder: insights from human postmortem brain tissue. Curr Drug Targets 2013; 14:1225-36. [PMID: 23469922 PMCID: PMC3799810 DOI: 10.2174/13894501113149990156] [Citation(s) in RCA: 413] [Impact Index Per Article: 37.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Revised: 02/22/2013] [Accepted: 02/26/2013] [Indexed: 02/07/2023]
Abstract
The present paper reviews astrocyte pathology in major depressive disorder (MDD) and proposes that reductions in astrocytes and related markers are key features in the pathology of MDD. Astrocytes are the most numerous and versatile of all types of glial cells. They are crucial to the neuronal microenvironment by regulating glucose metabolism, neurotransmitter uptake (particularly for glutamate), synaptic development and maturation and the blood brain barrier. Pathology of astrocytes has been consistently noted in MDD as well as in rodent models of depressive-like behavior. This review summarizes evidence from human postmortem tissue showing alterations in the expression of protein and mRNA for astrocyte markers such as glial fibrillary acidic protein (GFAP), gap junction proteins (connexin 40 and 43), the water channel aquaporin-4 (AQP4), a calcium-binding protein S100B and glutamatergic markers including the excitatory amino acid transporters 1 and 2 (EAAT1, EAAT2) and glutamine synthetase. Moreover, preclinical studies are presented that demonstrate the involvement of GFAP and astrocytes in animal models of stress and depressive-like behavior and the influence of different classes of antidepressant medications on astrocytes. In light of the various astrocyte deficits noted in MDD, astrocytes may be novel targets for the action of antidepressant medications. Possible functional consequences of altered expression of astrocytic markers in MDD are also discussed. Finally, the unique pattern of cell pathology in MDD, characterized by prominent reductions in the density of astrocytes and in the expression of their markers without obvious neuronal loss, is contrasted with that found in other neuropsychiatric and neurodegenerative disorders.
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Affiliation(s)
- Grazyna Rajkowska
- Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, 2500 N. State St., Box 127, Jackson, MS 39216-4505, USA.
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22
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Malynn S, Campos-Torres A, Moynagh P, Haase J. The pro-inflammatory cytokine TNF-α regulates the activity and expression of the serotonin transporter (SERT) in astrocytes. Neurochem Res 2013; 38:694-704. [PMID: 23338678 DOI: 10.1007/s11064-012-0967-y] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Revised: 12/20/2012] [Accepted: 12/26/2012] [Indexed: 01/28/2023]
Abstract
Pro-inflammatory cytokines have been implicated in the precipitation of depression and related disorders, and the antidepressant sensitive serotonin transporter (SERT) may be a major target for immune regulation in these disorders. Here, we focus on astrocytes, a major class of immune competent cells in the brain, to examine the effects of pro-longed treatment with tumor necrosis factor-alpha (TNF-α) on SERT activity. We first established that high-affinity serotonin uptake into C6 glioma cells occurs through a SERT-dependent mechanism. Functional SERT expression is also confirmed for primary astrocytes. In both cell types, exposure to TNF-α resulted in a dose- and time-dependent increase in SERT-mediated 5-HT uptake, which was sustained for at least 48 h post-stimulation. Further analysis in primary astrocytes revealed that TNF-α enhanced the transport capacity (Vmax) of SERT-specific 5-HT uptake, suggesting enhanced transporter expression, consistent with our observation of an increase in SERT mRNA levels. We confirmed that in both, primary astrocytes and C6 glioma cells, treatment with TNF-α activates the p38 mitogen-activated protein kinase (MAPK) signaling pathway. Pre-treatment with the p38 MAPK inhibitor SB203580 attenuated the TNF-α mediated stimulation of 5-HT transport in both, C6 glioma and primary astrocytes. In summary, we show that SERT gene expression and activity in astrocytes is subject to regulation by TNF-α, an effect that is at least in part dependent on p38 MAPK activation.
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Affiliation(s)
- Sandra Malynn
- UCD School of Biomolecular and Biomedical Science, UCD Conway Institute, University College Dublin, Dublin 4, Ireland
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23
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Kuo J, Micevych P. Neurosteroids, trigger of the LH surge. J Steroid Biochem Mol Biol 2012; 131:57-65. [PMID: 22326732 PMCID: PMC3474707 DOI: 10.1016/j.jsbmb.2012.01.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2011] [Revised: 01/19/2012] [Accepted: 01/22/2012] [Indexed: 12/28/2022]
Abstract
Recent experiments from our laboratory are consistent with the idea that hypothalamic astrocytes are critical components of the central nervous system (CNS) mediated estrogen positive feedback mechanism. The "astrocrine hypothesis" maintains that ovarian estradiol rapidly increases free cytoplasmic calcium concentrations ([Ca(2+)](i)) that facilitate progesterone synthesis in astrocytes. This hypothalamic neuroprogesterone along with the elevated estrogen from the ovaries allows for the surge release of gonadotropin-releasing hormone (GnRH) that triggers the pituitary luteinizing hormone (LH) surge. A narrow range of estradiol stimulated progesterone production supports an "off-on-off" mechanism regulating the transition from estrogen negative feedback to estrogen positive feedback, and back again. The rapidity of the [Ca(2+)](i) response and progesterone synthesis support a non-genomic, membrane-initiated signaling mechanism. In hypothalamic astrocytes, membrane-associated estrogen receptors (mERs) signal through transactivation of the metabotropic glutamate receptor type 1a (mGluR1a), implying that astrocytic function is influenced by surrounding glutamatergic nerve terminals. Although other putative mERs, such as mERβ, STX-activated mER-Gα(q), and G protein-coupled receptor 30 (GPR30), are present and participate in membrane-mediated signaling, their influence in reproduction is still obscure since female reproduction be it estrogen positive feedback or lordosis behavior requires mERα. The astrocrine hypothesis is also consistent with the well-known sexual dimorphism of estrogen positive feedback. In rodents, only post-pubertal females exhibit this positive feedback. Hypothalamic astrocytes cultured from females, but not males, responded to estradiol by increasing progesterone synthesis. Estrogen autoregulates its own signaling by regulating levels of mERα in the plasma membrane of female astrocytes. In male astrocytes, the estradiol-induced increase in mERα was attenuated, suggesting that membrane-initiated estradiol signaling (MIES) would also be blunted. Indeed, estradiol induced [Ca(2+)](i) release in male astrocytes, but not to levels required to stimulate progesterone synthesis. Investigation of this sexual differentiation was performed using hypothalamic astrocytes from post-pubertal four core genotype (FCG) mice. In this model, genetic sex is uncoupled from gonadal sex. We demonstrated that animals that developed testes (XYM and XXM) lacked estrogen positive feedback, strongly suggesting that the sexual differentiation of progesterone synthesis is driven by the sex steroid environment during early development. This article is part of a Special Issue entitled 'Neurosteroids'.
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Affiliation(s)
- John Kuo
- Department of Neurobiology, Laboratory of Neuroendocrinology of the Brain Research Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, United States
- Department of Obstetrics and Gynecology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, United States
| | - Paul Micevych
- Department of Neurobiology, Laboratory of Neuroendocrinology of the Brain Research Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, United States
- Corresponding author at: Department of Neurobiology, David Geffen School of Medicine at UCLA, 10833 LeConte Avenue, 73-078 CHS, Los Angeles, CA 90095-1763, United States. Tel.: +1 310 206 8265; fax: +1 310 825 2224. (P. Micevych)
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Shinozaki G. The integrated model of serotonin transporter gene variation (5HTTLPR) and the glial cell transporter in stress vulnerability and depression. Med Hypotheses 2012; 78:410-4. [PMID: 22236459 DOI: 10.1016/j.mehy.2011.10.043] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Revised: 07/08/2011] [Accepted: 10/27/2011] [Indexed: 10/14/2022]
Abstract
The serotonin transporter gene (SLC6A4) promoter polymorphism (5HTTLPR) has been associated with individual stress responses such that individuals with childhood abuse history have higher rates of depression in later life if they are homozygous short (s/s) of the gene. It is hypothesized that these findings could be explained by an integrated model of a role of the glial cell transporter and a functional difference of 5HTTLPR in the capacity of absorbing serotonin from the synapse. A hypothetical integrated model of the SLC6A4 function and the role of glial cells are put forward to explain accumulating results of recent investigations exploring the relationship between the gene and the diverse mental activities including depression and stress response. A model based on SLC6A4 variation is proposed to explain individual differences in stress vulnerability/resilience. The role of the glial cell transporter surrounding the synapse is integrated in the model to understand the modulation of the neurotransmission. It is hypothesized that a synapse with less serotonin transporter contributes to unstable processing in neurotransmission as compared to a synapse with more serotonin transporter. As such, based on functional differences of 5HTTLPR in the expression of the serotonin transporter, it is asserted that individuals with the s/s genotype process neurotransmission differently and in a reactive way. This integrated model of 5HTTLPR and glial cells suggests that the efficacy of serotonin reuptake in the synapse may play a crucial role in variability of neurotransmission, which can lead to differences in the stress response and the pathophysiology of depression.
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Affiliation(s)
- Gen Shinozaki
- Department of Psychiatry and Psychology, Mayo Clinic, Rochester, MN, United States.
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25
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Carbone M, Duty S, Rattray M. Riluzole elevates GLT-1 activity and levels in striatal astrocytes. Neurochem Int 2011; 60:31-8. [PMID: 22080156 DOI: 10.1016/j.neuint.2011.10.017] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2011] [Revised: 10/20/2011] [Accepted: 10/28/2011] [Indexed: 12/12/2022]
Abstract
Drugs which upregulate astrocyte glutamate transport may be useful neuroprotective compounds by preventing excitotoxicity. We set up a new system to identify potential neuroprotective drugs which act through GLT-1. Primary mouse striatal astrocytes grown in the presence of the growth-factor supplement G5 express high levels of the functional glutamate transporter, GLT-1 (also known as EAAT2) as assessed by Western blotting and ³H-glutamate uptake assay, and levels decline following growth factor withdrawal. The GLT-1 transcriptional enhancer dexamethasone (0.1 or 1 μM) was able to prevent loss of GLT-1 levels and activity following growth factor withdrawal. In contrast, ceftriaxone, a compound previously reported to enhance GLT-1 expression, failed to regulate GLT-1 in this system. The neuroprotective compound riluzole (100 μM) upregulated GLT-1 levels and activity, through a mechanism that was not dependent on blockade of voltage-sensitive ion channels, since zonasimide (1 mM) did not regulate GLT-1. Finally, CDP-choline (10 μM-1 mM), a compound which promotes association of GLT-1/EAAT2 with lipid rafts was unable to prevent GLT-1 loss under these conditions. This observation extends the known pharmacological actions of riluzole, and suggests that this compound may exert its neuroprotective effects through an astrocyte-dependent mechanism.
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Affiliation(s)
- Marica Carbone
- King's College London, Wolfson Centre for Age-Related Diseases, Guy's Campus, London SE1 1UL, UK
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26
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Bruchas MR, Schindler AG, Shankar H, Messinger DI, Miyatake M, Land BB, Lemos JC, Hagan CE, Neumaier JF, Quintana A, Palmiter RD, Chavkin C. Selective p38α MAPK deletion in serotonergic neurons produces stress resilience in models of depression and addiction. Neuron 2011; 71:498-511. [PMID: 21835346 DOI: 10.1016/j.neuron.2011.06.011] [Citation(s) in RCA: 208] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/01/2011] [Indexed: 12/12/2022]
Abstract
Maladaptive responses to stress adversely affect human behavior, yet the signaling mechanisms underlying stress-responsive behaviors remain poorly understood. Using a conditional gene knockout approach, the α isoform of p38 mitogen-activated protein kinase (MAPK) was selectively inactivated by AAV1-Cre-recombinase infection in specific brain regions or by promoter-driven excision of p38α MAPK in serotonergic neurons (by Slc6a4-Cre or ePet1-Cre) or astrocytes (by Gfap-CreERT2). Social defeat stress produced social avoidance (a model of depression-like behaviors) and reinstatement of cocaine preference (a measure of addiction risk) in wild-type mice, but not in mice having p38α MAPK selectively deleted in serotonin-producing neurons of the dorsal raphe nucleus. Stress-induced activation of p38α MAPK translocated the serotonin transporter to the plasma membrane and increased the rate of transmitter uptake at serotonergic nerve terminals. These findings suggest that stress initiates a cascade of molecular and cellular events in which p38α MAPK induces a hyposerotonergic state underlying depression-like and drug-seeking behaviors.
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Affiliation(s)
- Michael R Bruchas
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA.
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27
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Characterization of GABA(A) receptors expressed in glial cell membranes of adult mouse neocortex using a Xenopus oocyte microtransplantation expression system. J Neurosci Methods 2011; 198:77-83. [PMID: 21439322 DOI: 10.1016/j.jneumeth.2011.03.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2010] [Revised: 03/09/2011] [Accepted: 03/10/2011] [Indexed: 11/21/2022]
Abstract
Cell membranes isolated from nervous tissue can be easily injected into Xenopus oocytes, thereby effectively "microtransplanting" functional neurotransmitter receptors. This technique therefore allows a direct functional characterization of the original membrane receptor/ion channel proteins and the associated molecules while still embedded in their natural lipid environment. Cell membranes will contain components from different types of cells, i.e. neurons and glial cells, expressing their own receptors, with possibly different properties. To study the receptor properties of a single cell type, we injected oocytes with membranes isolated only from glia (gliosomes) of adult mouse neocortex and we focused our work on GABA(A) receptors incorporated in the oocyte cell membrane. We found that GABA(A)-activated currents allowed a good biophysical and pharmacological characterization of glial GABA(A) receptors. Therefore, the microtransplantation of gliosomes into oocytes can represent a good model to study the electrical and pharmacological properties of adult glial cells under different physiological and pathological conditions. Moreover, since gliosomes can be isolated from frozen tissues, this approach can be extended to post-mortem human tissues.
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28
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Schipke CG, Heuser I, Peters O. Antidepressants act on glial cells: SSRIs and serotonin elicit astrocyte calcium signaling in the mouse prefrontal cortex. J Psychiatr Res 2011; 45:242-8. [PMID: 20619420 DOI: 10.1016/j.jpsychires.2010.06.005] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2010] [Revised: 06/02/2010] [Accepted: 06/08/2010] [Indexed: 11/24/2022]
Abstract
One important target in the treatment of major depressive disorder (MDD) is the serotonin (5-hydroxytryptamine, 5-HT) system. Selective serotonin reuptake inhibitors (SSRI) are used to treat MDD. Yet, the mode of action of these drugs is not completely understood. There is evolving evidence for a role of glutamate in mood disorder and its signaling. Astrocytes are involved in glutamate metabolism and play an active role in memory processing but their role in mood disorders is still largely unknown. A modulation of astrocytic signaling by SSRIs or 5-HT has not been investigated up to now. We investigated astrocytic calcium signaling with the calcium indicator dye Fluo-4. Using a confocal microscope, we imaged astrocytes in the medial prefrontal cortex of acute mouse brain slices after the application of the SSRIs citalopram and fluoxetine. In the same way, we studied the effects of serotonin and the modulation of this signaling by glutamate in astrocytes. We found that astrocyte calcium signaling can be elicited by 5-HT. Also, the SSRIs citalopram and fluoxetine induce calcium signals in about 1/3 of all astrocytes, even when neuronal signal propagation is inhibited. Astrocytic responses to 5-HT have a unique pattern and they could mostly not be evoked twice. We determined that glutamate is a substance that can interfere with 5-HT-induced calcium signals in astrocytes since after stimulation by glutamate, astrocytes did not show a response to 5-HT. Astrocytic calcium signaling is elicited by SSRIs and 5-HT. They may serve as integrators, linking the serotonergic and glutamatergic signaling pathways.
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Affiliation(s)
- Carola G Schipke
- Department of Psychiatry, Charité Universitätsmedizin Berlin, Campus Benjamin Franklin, Germany.
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Micevych P, Sinchak K. The Neurosteroid Progesterone Underlies Estrogen Positive Feedback of the LH Surge. Front Endocrinol (Lausanne) 2011; 2:90. [PMID: 22654832 PMCID: PMC3356049 DOI: 10.3389/fendo.2011.00090] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2011] [Accepted: 11/16/2011] [Indexed: 01/25/2023] Open
Abstract
Our understanding the steroid regulation of neural function has rapidly evolved in the past decades. Not long ago the prevailing thoughts were that peripheral steroid hormones carried information to the brain which passively responded to these steroids. These steroid actions were slow, taking hours to days to be realized because they regulated gene expression. Over the past three decades, discoveries of new steroid receptors, rapid membrane-initiated signaling mechanisms, and de novo neurosteroidogenesis have shed new light on the complexity of steroids actions within the nervous system. Sexual differentiation of the brain during development occurs predominately through timed steroid-mediated expression of proteins and long term epigenetic modifications. In contrast across the estrous cycle, estradiol release from developing ovarian follicles initially increases slowly and then at proestrus increases rapidly. This pattern of estradiol release acts through both classical genomic mechanisms and rapid membrane-initiated signaling in the brain to coordinate reproductive behavior and physiology. This review focuses on recently discovered estrogen receptor-α membrane signaling mechanisms that estradiol utilizes during estrogen positive feedback to stimulate de novo progesterone synthesis within the hypothalamus to trigger the luteinizing hormone (LH) surge important for ovulation and estrous cyclicity. The activation of these signaling pathways appears to be coordinated by the rising and waning of estradiol throughout the estrous cycle and integral to the negative and positive feedback mechanisms of estradiol. This differential responsiveness is part of the timing mechanism triggering the LH surge.
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Affiliation(s)
- Paul Micevych
- Laboratory of Neuroendocrinology, Department of Neurobiology, David Geffen School of Medicine, Brain Research Institute, University of CaliforniaLos Angeles, CA, USA
- *Correspondence: Paul Micevych, Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, CA 90095-1763, USA. e-mail:
| | - Kevin Sinchak
- Department of Biological Sciences, California State UniversityLong Beach, CA, USA
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Li B, Zhang S, Li M, Hertz L, Peng L. Serotonin increases ERK1/2 phosphorylation in astrocytes by stimulation of 5-HT2B and 5-HT2C receptors. Neurochem Int 2010; 57:432-9. [PMID: 20450948 DOI: 10.1016/j.neuint.2010.04.017] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2009] [Revised: 03/24/2010] [Accepted: 04/26/2010] [Indexed: 11/29/2022]
Abstract
We have previously shown that fluoxetine causes ERK(1/2) phosphorylation in cultured mouse astrocytes mediated exclusively by stimulation of 5-HT(2B) receptors (Li et al., 2008b). This raises the question whether this is also the case for serotonin (5-HT) itself. In the present study serotonin was found to induce ERK(1/2) phosphorylation by stimulation of 5-HT(2B) receptors with high affinity (EC(50): 20-30 pM), and by stimulation of 5-HT(2C) receptor with low affinity (EC(50): 1 microM or higher). ERK(1/2) phosphorylation induced by stimulation of either 5-HT(2B) or 5-HT(2C) receptors was mediated by epidermal growth factor (EGF) receptor transactivation (Peng et al., this issue), shown by the inhibitory effect of AG1478, an inhibitor of the EGF receptor tyrosine kinase, and GM6001, an inhibitor of Zn-dependent metalloproteinases, and thus of 5-HT(2B) receptor-mediated EGF receptor agonist release. It is discussed that the high potency of the 5-HT(2B)-mediated effect is consistent with literature data for binding affinity of serotonin to cloned human 5-HT(2B) receptors and with observations of low extracellular concentrations of serotonin in brain, which would allow a demonstrated moderate and modality-dependent increase in specific brain areas to activate 5-HT(2B) receptors. In contrast the relevance of the observed 5-HT(2C) receptors on astrocytes is questioned.
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Affiliation(s)
- Baoman Li
- Department of Clinical Pharmacology, China Medical University, Heping District, Shenyang, PR China
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Coleman ES, Dennis JC, Braden TD, Judd RL, Posner P. Insulin treatment prevents diabetes-induced alterations in astrocyte glutamate uptake and GFAP content in rats at 4 and 8 weeks of diabetes duration. Brain Res 2010; 1306:131-41. [PMID: 19822133 PMCID: PMC2787763 DOI: 10.1016/j.brainres.2009.10.005] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2009] [Revised: 10/01/2009] [Accepted: 10/02/2009] [Indexed: 01/10/2023]
Abstract
Rat astrocyte function is changed by diabetes mellitus relative to the nondiabetic state and we believe that altered function contributes to the central nervous system symptoms manifested by individuals with diabetes. We report here a comparison of astrocyte glutamate uptake and GFAP expression in streptozotocin-induced type 1 diabetic rats and insulin-treated diabetic rats at 4 and 8 weeks following diabetes onset. In glial plasmalemmal vesicle (GPV) preparations from treated rats, insulin prevented the increase observed in untreated, diabetic rats of both sodium-dependent and sodium-independent glutamate uptake. We determined by immunoblotting and immunohistochemistry that insulin treatment prevented the decrease of GFAP expression detected in the cerebral cortex, hippocampus, and cerebellum of untreated, diabetic rats. These observations indicate that insulin effects on astrocyte function are significant in managing diabetes-induced central nervous system pathology.
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Affiliation(s)
- Elaine S Coleman
- Department of Anatomy, Physiology, and Pharmacology, College of Veterinary Medicine, 109 Greene Hall, Auburn University, Auburn, AL 36849, USA.
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Kuo J, Hariri OR, Micevych P. An interaction of oxytocin receptors with metabotropic glutamate receptors in hypothalamic astrocytes. J Neuroendocrinol 2009; 21:1001-6. [PMID: 19807846 PMCID: PMC2804744 DOI: 10.1111/j.1365-2826.2009.01922.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Hypothalamic astrocytes play a critical role in the regulation and support of many different neuroendocrine events, and are affected by oestradiol. Both nuclear and membrane oestrogen receptors (ERs) are expressed in astrocytes. Upon oestradiol activation, membrane-associated ER signals through the type 1a metabotropic glutamate receptor (mGluR1a) to induce an increase of free cytoplasmic calcium concentration ([Ca(2+)](i)). Because the expression of oxytocin receptors (OTRs) is modulated by oestradiol, we tested whether oestradiol also influences oxytocin signalling. Oxytocin at 1, 10, and 100 nm induced a [Ca(2+)](i) flux measured as a change in relative fluorescence [DeltaF Ca(2+) = 330 +/- 17 relative fluorescent units (RFU), DeltaF Ca(2+) = 331 +/- 22 RFU, and DeltaF Ca(2+) = 347 +/- 13 RFU, respectively] in primary cultures of female post-pubertal hypothalamic astrocytes. Interestingly, OTRs interacted with mGluRs. The mGluR1a antagonist, LY 367385 (20 nm), blocked the oxytocin (1 nm)-induced [Ca(2+)](i) flux (DeltaF Ca(2+) = 344 +/- 19 versus 127 +/- 11 RFU, P < 0.001). Conversely, the mGluR1a receptor agonist, (RS)-3,5-dihydroxyphenyl-glycine (100 nm), increased the oxytocin (1 nm)-induced [Ca(2+)](i) response (DeltaF Ca(2+) = 670 +/- 31 RFU) compared to either compound alone (P < 0.001). Because both oxytocin and oestradiol rapidly signal through the mGluR1a, we treated hypothalamic astrocytes sequentially with oxytocin and oestradiol to determine whether stimulation with one hormone affected the subsequent [Ca(2+)](i) response to the second hormone. Oestradiol treatment did not change the subsequent [Ca(2+)](i) flux to oxytocin (P > 0.05) and previous oxytocin exposure did not affect the [Ca(2+)](i) response to oestradiol (P > 0.05). Furthermore, simultaneous oestradiol and oxytocin stimulation failed to yield a synergistic [Ca(2+)](i) response. These results suggest that the OTR signals through the mGluR1a to release Ca(2+) from intracellular stores and rapid, nongenomic oestradiol stimulation does not influence OTR signalling in astrocytes.
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Affiliation(s)
- John Kuo
- Department of Neurobiology, Laboratory of Neuroendocrinology and Brain Research Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095
- Department of Obstetrics and Gynecology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095
| | - Omid R. Hariri
- Department of Neurobiology, Laboratory of Neuroendocrinology and Brain Research Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095
| | - Paul Micevych
- Department of Neurobiology, Laboratory of Neuroendocrinology and Brain Research Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095
- Corresponding author and reprint requests: Dr. Paul Micevych, Dept. of Neurobiology, David Geffen School of Medicine at UCLA, 10833 LeConte Avenue, 73-078 CHS, Los Angeles, CA 90095-1763, United States of America, Office: (310) 206-8265, Fax: (310) 825-2224,
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Liu Q, Li B, Zhu HY, Wang YQ, Yu J, Wu GC. Clomipramine treatment reversed the glial pathology in a chronic unpredictable stress-induced rat model of depression. Eur Neuropsychopharmacol 2009; 19:796-805. [PMID: 19616923 DOI: 10.1016/j.euroneuro.2009.06.010] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2009] [Revised: 05/26/2009] [Accepted: 06/09/2009] [Indexed: 01/17/2023]
Abstract
Growing evidence indicates that glia pathology contributes to the pathophysiology and possibly the etiology of depression. The study investigates changes in behaviors and glial fibrillary associated protein (GFAP) in the rat hippocampus after chronic unpredictable stress (CUS), a rat model of depression. Furthermore, we studied the effects of clomipramine, one of tricyclic antidepressants (TCAs), known to modulate serotonin and norepinephrine uptake, on CUS-induced depressive-like behaviors and GFAP levels. Rats exposed to CUS showed behavioral deficits in physical state, open field test and forced swimming test and exhibited a significant decrease in GFAP expression in the hippocampus. Interestingly, the behavioral and GFAP expression changes induced by CUS were reversed by chronic treatment with the antidepressant clomipramine. The beneficial effects of clomipramine treatment on CUS-induced depressive-like behavior and GFAP expression provide further validation of our hypothesis that glial dysfunction contributes to the pathophysiology of depression and that glial elements may represent viable targets for new antidepressant drug development.
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Affiliation(s)
- Qiong Liu
- Institute of Acupuncture Research (WHO Collaborating Center for Traditional Medicine), Institutes of Brain Science, Department of Integrative Medicine and Neurobiology, State Key Laboratory of Medical Neurobiology, Shanghai Medical College, Fudan University, Shanghai 200032, China
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Glutamate release from astrocytic gliosomes under physiological and pathological conditions. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2009; 85:295-318. [PMID: 19607977 DOI: 10.1016/s0074-7742(09)85021-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
Glial subcellular particles (gliosomes) have been purified from rat cerebral cortex or mouse spinal cord and investigated for their ability to release glutamate. Confocal microscopy showed that gliosomes are enriched with glia-specific proteins, such as GFAP and S-100 but not neuronal proteins, such as PSD-95, MAP-2, and beta-tubulin III. Furthermore, gliosomes exhibit labeling neither for integrin-alphaM nor for myelin basic protein, specific for microglia and oligodendrocytes, respectively. The gliosomal fraction contains proteins of the exocytotic machinery coexisting with GFAP. Consistent with ultrastructural analysis, several nonclustered vesicles are present in the gliosome cytoplasm. Finally, gliosomes represent functional organelles that actively export glutamate when subjected to releasing stimuli, such as ionomycin, high KCl, veratrine, 4-aminopyridine, AMPA, or ATP by mechanisms involving extracellular Ca2+, Ca2+ release from intracellular stores as well as reversal of glutamate transporters. In addition, gliosomes can release glutamate also by a mechanism involving heterologous transporter activation (heterotransporters) located on glutamate-releasing and glutamate transporter-expressing (homotransporters) gliosomes. This glutamate release involves reversal of glutamate transporters and anion channel opening, but not exocytosis. Both the exocytotic and the heterotransporter-mediated glutamate release were more abundant in gliosomes prepared from the spinal cord of transgenic mice, model of amyotrophic lateral sclerosis, than in controls; suggesting the involvement of astrocytic glutamate release in the excitotoxicity proposed as a cause of motor neuron degeneration. The results support the view that gliosomes may represent a viable preparation that allows to study mechanisms of astrocytic transmitter release and its regulation in healthy animals and in animal models of brain diseases.
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Kuo J, Hariri OR, Bondar G, Ogi J, Micevych P. Membrane estrogen receptor-alpha interacts with metabotropic glutamate receptor type 1a to mobilize intracellular calcium in hypothalamic astrocytes. Endocrinology 2009; 150:1369-76. [PMID: 18948402 PMCID: PMC2654734 DOI: 10.1210/en.2008-0994] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Estradiol, acting on a membrane-associated estrogen receptor-alpha (mERalpha), induces an increase in free cytoplasmic calcium concentration ([Ca(2+)](i)) needed for progesterone synthesis in hypothalamic astrocytes. To determine whether rapid estradiol signaling involves an interaction of mERalpha with metabotropic glutamate receptor type 1a (mGluR1a), changes in [Ca(2+)](i) were monitored with the calcium indicator, Fluo-4 AM, in primary cultures of female postpubertal hypothalamic astrocytes. 17beta-Estradiol over a range of 1 nm to 100 nm induced a maximal increase in [Ca(2+)](i) flux measured as a change in relative fluorescence [DeltaF Ca(2+) = 615 +/- 36 to 641 +/- 47 relative fluorescent units (RFU)], whereas 0.1 nm of estradiol stimulated a moderate [Ca(2+)](i) increase (275 +/- 16 RFU). The rapid estradiol-induced [Ca(2+)](i) flux was blocked with 1 microm of the estrogen receptor antagonist ICI 182,780 (635 +/- 24 vs. 102 +/- 11 RFU, P < 0.001) and 20 nmof the mGluR1a antagonist LY 367385 (617 +/- 35 vs. 133 +/- 20 RFU, P < 0.001). Whereas the mGluR1a receptor agonist (RS)-3,5-dihydroxyphenyl-glycine (50 microm) also stimulated a robust [Ca(2+)](i) flux (626 +/- 23 RFU), combined treatment of estradiol (1 nm) plus (RS)-3,5-dihydroxyphenyl-glycine (50 microm) augmented the [Ca(2+)](i) response (762 +/- 17 RFU) compared with either compound alone (P < 0.001). Coimmunoprecipitation demonstrated a direct physical interaction between mERalpha and mGluR1a in the plasma membrane of hypothalamic astrocytes. These results indicate that mERalpha acts through mGluR1a, and mGluR1a activation facilitates the estradiol response, suggesting that neural activity can modify estradiol-induced membrane signaling in astrocytes.
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Affiliation(s)
- John Kuo
- Department of Neurobiology, David Geffen School of Medicine at University of California, Los Angeles, 10833 LeConte Avenue, 73-078 CHS, Los Angeles, California 90095-1763.
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Perdan K, Lipnik‐Štangelj M, Kržan M. Chapter 8 The Impact of Astrocytes in the Clearance of Neurotransmitters by Uptake and Inactivation. ADVANCES IN PLANAR LIPID BILAYERS AND LIPOSOMES 2009. [DOI: 10.1016/s1554-4516(09)09008-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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Paluzzi S, Alloisio S, Zappettini S, Milanese M, Raiteri L, Nobile M, Bonanno G. Adult astroglia is competent for Na+/Ca2+ exchanger-operated exocytotic glutamate release triggered by mild depolarization. J Neurochem 2007; 103:1196-207. [PMID: 17935604 DOI: 10.1111/j.1471-4159.2007.04826.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Glutamate release induced by mild depolarization was studied in astroglial preparations from the adult rat cerebral cortex, that is acutely isolated glial sub-cellular particles (gliosomes), cultured adult or neonatal astrocytes, and neuron-conditioned astrocytes. K+ (15, 35 mmol/L), 4-aminopyridine (0.1, 1 mmol/L) or veratrine (1, 10 micromol/L) increased endogenous glutamate or [3H]D-aspartate release from gliosomes. Neurotransmitter release was partly dependent on external Ca2+, suggesting the involvement of exocytotic-like processes, and partly because of the reversal of glutamate transporters. K+ increased gliosomal membrane potential, cytosolic Ca2+ concentration [Ca2+]i, and vesicle fusion rate. Ca2+ entry into gliosomes and glutamate release were independent from voltage-sensitive Ca2+ channel opening; they were instead abolished by 2-[2-[4-(4-nitrobenzyloxy)phenyl]ethyl]isothiurea (KB-R7943), suggesting a role for the Na+/Ca2+ exchanger working in reverse mode. K+ (15, 35 mmol/L) elicited increase of [Ca2+]i and Ca2+-dependent endogenous glutamate release in adult, not in neonatal, astrocytes in culture. Glutamate release was even more marked in in vitro neuron-conditioned adult astrocytes. As seen for gliosomes, K+-induced Ca2+ influx and glutamate release were abolished by KB-R7943 also in cultured adult astrocytes. To conclude, depolarization triggers in vitro glutamate exocytosis from in situ matured adult astrocytes; an aptitude grounding on Ca2+ influx driven by the Na+/Ca2+ exchanger working in the reverse mode.
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Affiliation(s)
- Silvio Paluzzi
- Department of Experimental Medicine, Pharmacology and Toxicology Section, University of Genoa, Genoa, Italy
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Bonanno G, Raiteri L, Milanese M, Zappettini S, Melloni E, Pedrazzi M, Passalacqua M, Tacchetti C, Usai C, Sparatore B. The high-mobility group box 1 cytokine induces transporter-mediated release of glutamate from glial subcellular particles (gliosomes) prepared from in situ-matured astrocytes. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2007; 82:73-93. [PMID: 17678956 DOI: 10.1016/s0074-7742(07)82004-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
Abstract
The multifunctional protein high-mobility group box 1 (HMGB1) is expressed in restricted areas of adult brain where it can act as a proinflammatory cytokine. We report here that HMGB1 affects CNS transmission by inducing glutamatergic release from glial (gliosomes) but not neuronal (synaptosomes) resealed subcellular particles isolated from mouse cerebellum and hippocampus. Confocal microscopy showed that gliosomes are enriched with glia-specific proteins such as GFAP and S-100, but not with neuronal proteins such as PSD-95, MAP-2, and beta-tubulin III. Furthermore, gliosomes exhibit labeling neither for integrin-alphaM nor for myelin basic protein, specific for microglia and oligodendrocytes, respectively. The gliosomal fraction contains proteins of the exocytotic machinery coexisting with GFAP. Consistent with ultrastructural analysis, several approximately 30-nm nonclustered vesicles are present in the gliosome cytoplasm. Finally, gliosomes represent functional organelles that actively export glutamate when subjected to releasing stimuli, such as ionomycin or ATP, by mechanisms involving extracellular Ca(2+) and Ca(2+) release from intracellular stores. HMGB1-induced release of the stable glutamate analogue [(3)H]d-aspartate and endogenous glutamate form gliosomes, whereas nerve terminals were insensitive to the protein. The HMGB1-evoked release of glutamate was independent on modifications of cytosolic Ca(2+) concentration, but it was blocked by dl-threo-beta-benzyloxyaspartate, suggesting the involvement of transporter-mediated release mechanisms. Moreover, dihydrokainic acid, a selective inhibitor of glutamate transporter 1 does not block the HMGB1 effect, indicating a role for the glial glutamate-aspartate transporter (GLAST) subtype in this response. HMGB1 bind to gliosomes but not to synaptosomes and can physically interact with GLAST and receptor for advanced glycation end products (RAGE). Taken together, these results suggest that the HMGB1 cytokine could act as a modulator of glutamate homeostasis in adult mammalian brain.
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Affiliation(s)
- Giambattista Bonanno
- Department of Experimental Medicine, Section of Pharmacology and Toxicology University of Genoa, Italy
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Patti L, Raiteri L, Grilli M, Zappettini S, Bonanno G, Marchi M. Evidence that α7 nicotinic receptor modulates glutamate release from mouse neocortical gliosomes. Neurochem Int 2007; 51:1-7. [PMID: 17462791 DOI: 10.1016/j.neuint.2007.03.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2007] [Revised: 03/05/2007] [Accepted: 03/07/2007] [Indexed: 11/23/2022]
Abstract
The presence of nicotinic receptors on astrocytes in human and rat brain has been previously demonstrated however their possible functional role is still poorly understood. In this study we investigated on the presence of nicotinic receptors on gliosomes, purified from mouse cortex, and on their role in eliciting glutamate release. Epibatidine significantly increased basal release of [3H]D-aspartate and of endogenous glutamate from mouse gliosomes but not from synaptosomes. This effect was prevented by methyllycaconitine, alpha-bungarotoxin and mecamylamine but not by dihydro-beta-erythroidine. Epibatidine provoked also a significant increase of calcium concentration in gliosomes but not in synaptosomes; the increase in [Ca2+]i induced by epibatidine and KCl in gliosomes was very similar to each other. The present results indicate that alpha7 nicotinic receptors exist on mouse cortical glial particles and stimulate glutamate release.
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Affiliation(s)
- Laura Patti
- Sezione di Farmacologia e Tossicologia, Dipartimento di Medicina Sperimentale, Università degli Studi di Genova, Viale Cembrano 4, 16148 Genoa, Italy
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Rajkowska G, Miguel-Hidalgo JJ. Gliogenesis and glial pathology in depression. CNS & NEUROLOGICAL DISORDERS-DRUG TARGETS 2007; 6:219-33. [PMID: 17511618 PMCID: PMC2918806 DOI: 10.2174/187152707780619326] [Citation(s) in RCA: 431] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Recent research has changed the perception of glia from being no more than silent supportive cells of neurons to being dynamic partners participating in brain metabolism and communication between neurons. This discovery of new glial functions coincides with growing evidence of the involvement of glia in the neuropathology of mood disorders. Unanticipated reductions in the density and number of glial cells are reported in fronto-limbic brain regions in major depression and bipolar illness. Moreover, age-dependent decreases in the density of glial fibrillary acidic protein (GFAP) - immunoreactive astrocytes and levels of GFAP protein are observed in the prefrontal cortex of younger depressed subjects. Since astrocytes participate in the uptake, metabolism and recycling of glutamate, we hypothesize that an astrocytic deficit may account for the alterations in glutamate/GABA neurotransmission in depression. Reductions in the density and ultrastructure of oligodendrocytes are also detected in the prefrontal cortex and amygdala in depression. Pathological changes in oligodendrocytes may be relevant to the disruption of white matter tracts in mood disorders reported by diffusion tensor imaging. Factors such as stress, excess of glucocorticoids, altered gene expression of neurotrophic factors and glial transporters, and changes in extracellular levels of neurotransmitters released by neurons may modify glial cell number and affect the neurophysiology of depression. Therefore, we will explore the role of these events in the possible alteration of glial number and activity, and the capacity of glia as a promising new target for therapeutic medications. Finally, we will consider the temporal relationship between glial and neuronal cell pathology in depression.
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Affiliation(s)
- G Rajkowska
- Department of Psychiatry, University of Mississippi Medical Center, Jackson, MS 39216-4505, USA.
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Katafuchi T, Kondo T, Take S, Yoshimura M. Brain cytokines and the 5-HT system during poly I:C-induced fatigue. Ann N Y Acad Sci 2007; 1088:230-7. [PMID: 17192569 DOI: 10.1196/annals.1366.020] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Fatigue is evoked not only by peripheral factors, such as muscle fatigue, but also by the central nervous system (CNS). For example, it is generally known that the feeling of fatigue is greatly influenced by psychological aspects, such as motivation. However, little is known about the central mechanisms of fatigue. The clinical symptoms of chronic fatigue syndrome (CFS) are shown to include disorders in neuroendocrine, autonomic, and immune systems. On the other hand, it has been demonstrated that cytokines produced in the brain play significant roles in neural-immune interactions through their various central actions, including hypothalamo-pituitary and sympathetic activation, as well as immunosuppression. In this article, using the immunologically induced fatigue model, which was achieved by intraperitoneal (i.p.) injection of synthetic double-stranded RNAs, polyriboinosinic: polyribocytidylic acid (poly I:C) in rats, we show an involvement of brain interferon-alpha (IFN-alpha) and serotonin (5-HT) transporter (5-HTT) in the central mechanisms of fatigue. In the poly I:C-induced fatigue rats, expression of IFN-alpha and 5-HTT increased, while extracellular concentration of 5-HT in the medial prefrontal cortex decreased, probably on account of the enhanced expression of 5-HTT. Since the poly I:C-induced reduction of the running wheel activity was attenuated by a 5-HT(1A) receptor agonist, but not by 5-HT(2), 5-HT(3), or dopamine D(3) receptor agonists, it is suggested that the decrease in 5-HT actions on 5-HT(1A) receptors may at least partly contribute to the poly I:C-induced fatigue.
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Affiliation(s)
- Toshihiko Katafuchi
- Department of Integrative Physiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, 812-8582, Japan.
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42
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Pedrazzi M, Raiteri L, Bonanno G, Patrone M, Ledda S, Passalacqua M, Milanese M, Melloni E, Raiteri M, Pontremoli S, Sparatore B. Stimulation of excitatory amino acid release from adult mouse brain glia subcellular particles by high mobility group box 1 protein. J Neurochem 2006; 99:827-38. [PMID: 16911580 DOI: 10.1111/j.1471-4159.2006.04120.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The multifunctional protein high mobility group box 1 (HMGB1) is expressed in hippocampus and cerebellum of adult mouse brain. Our aim was to determine whether HMGB1 affects glutamatergic transmission by monitoring neurotransmitter release from glial (gliosomes) and neuronal (synaptosomes) re-sealed subcellular particles isolated from cerebellum and hippocampus. HMGB1 induced release of the glutamate analogue [(3)H]d-aspartate form gliosomes in a concentration-dependent manner, whereas nerve terminals were insensitive to the protein. The HMGB1-evoked release of [(3)H]d-aspartate was independent of modifications of cytosolic Ca(2+) , but it was blocked by dl-threo-beta-benzyloxyaspartate (dl-TBOA), an inhibitor of glutamate transporters. HMGB1 also stimulated the release of endogenous glutamate in a Ca(2+)-independent and dl-TBOA-sensitive manner. These findings suggest the involvement of carrier-mediated release. Moreover, dihydrokainic acid, a selective inhibitor of glutamate transporter 1 (GLT1), does not block the effect of HMGB1, indicating a role for the glial glutamate-aspartate transporter (GLAST) subtype in this response. We also demonstrate that HMGB1/glial particles association is promoted by Ca(2+). Furthermore, although HMGB1 can physically interact with GLAST and the receptor for advanced glycation end products (RAGE), only its binding with RAGE is promoted by Ca(2+). These results suggest that the HMGB1 cytokine could act as a modulator of glutamate homeostasis in adult mammal brain.
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Affiliation(s)
- Marco Pedrazzi
- Department of Experimental Medicine and Center of Excellence for Biomedical Research, University of Genoa, Genoa, Italy
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43
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Possible involvement of brain cytokines and 5-HT system in chronic fatigue syndrome. ACTA ACUST UNITED AC 2006. [DOI: 10.1016/j.ics.2005.09.177] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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44
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Hayat S, Williams RJ, Rattray M. Serotonin transporter expression is not sufficient to confer cytotoxicity to 3,4-methylenedioxymethamphetamine (MDMA) in vitro. J Psychopharmacol 2006; 20:257-63. [PMID: 16510483 DOI: 10.1177/0269881106063273] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
There is much evidence from animal studies that the recreational drug MDMA is a selective toxin which damages serotonin nerve terminals and axons. These in vivo studies show that an interaction between MDMA and the serotonin transporter protein (SERT) is the .rst step in toxicity. To further our understanding of the biochemical processes of MDMA toxicity we wished to use an in vitro model for toxicity. We produced two COS-7 cell lines with different levels of expression of recombinant rat SERT, as determined by 5-HT uptake assays, and compared them to human SERT expressing JAR cells and to untransfected COS-7 cells which do not express SERT. Cultured cells were exposed to MDMA (0.1 microM-1 mM) for 24 or 48 h at 37 degrees C before assessing cytotoxicity by LDH release and MTT turnover. Only at the highest concentration used, 1 mM, was MDMA cytotoxic, and this toxicity was found in all cell lines. Cytotoxicity caused by 48 h exposure to 1 mM MDMA at 37 degrees C was not related to the level of SERT expression, not blocked by the SERT-blocking drugs paroxetine or fluoxetine and not enhanced, in JAR cells, by forskolin preincubation that increased 5-HT uptake capacity by 50%. We conclude that SERT expression is not sufficient to confer MDMA toxicity to cell lines. Therefore SERT-expressing cell lines do not offer a simple model system to elucidate the mechanisms underlying MDMA toxicity.
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Affiliation(s)
- Shaista Hayat
- Laboratory of Molecular Signalling, The Babraham Institute, Cambridge, UK
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45
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Katafuchi T, Kondo T, Take S, Yoshimura M. Enhanced expression of brain interferon-alpha and serotonin transporter in immunologically induced fatigue in rats. Eur J Neurosci 2006; 22:2817-26. [PMID: 16324116 DOI: 10.1111/j.1460-9568.2005.04478.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Immunologically induced fatigue was induced in rats by intraperitoneal injection of a synthetic double-stranded RNA, polyriboinosinic : polyribocytidylic acid (poly I:C). An injection of poly I:C (3 mg/kg) decreased the daily amounts of spontaneous running wheel activity to approximately 60% of the preinjection level until day 8. Quantitative analysis of mRNA levels demonstrated that interferon-alpha (IFN-alpha) and p38 mitogen-activated protein kinase mRNAs increased in the medial preoptic, paraventricular and ventromedial hypothalamic nuclei and in cortex on both days 1 and 8, while interleukin-1beta and an inhibitor of nuclear factor kappaB (IkappaB)-beta mRNAs increased on day 1, but recovered within a week. Serotonin transporter (5-HTT) mRNA also increased on days 1 and 8 after poly I:C injection in the same brain regions where IFN-alpha mRNA increased. The increased 5-HTT had a functional significance, because in vivo brain microdialysis revealed that an i.p. injection of poly I:C induced a decrease in the extracellular concentration of 5-HT in the prefrontal cortex; the decrease was blocked by local perfusion with a nonselective 5-HT reuptake inhibitor, imipramine. Finally, the poly I:C-induced fatigue was attenuated by a 5-HT1A receptor agonist but not by 5-HT2, 5-HT3 or dopamine D3 agonists. These findings, taken together, suggest that disorders in brain IFN-alpha and 5-HTT expression may be involved in the neuronal mechanisms of the poly I:C-induced fatigue.
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Affiliation(s)
- Toshihiko Katafuchi
- Department of Integrative Physiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan.
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46
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Katafuchi T, Kondo T, Yasaka T, Kubo K, Take S, Yoshimura M. Prolonged effects of polyriboinosinic:polyribocytidylic acid on spontaneous running wheel activity and brain interferon-alpha mRNA in rats: a model for immunologically induced fatigue. Neuroscience 2003; 120:837-45. [PMID: 12895523 DOI: 10.1016/s0306-4522(03)00365-8] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Following 2 weeks acclimation to the running wheel in the home cages, an i.p. injection of a synthetic double-stranded RNA, polyriboinosinic:polyribocytidylic acid (poly I:C, 3 mg/kg), was performed to produce the immunologically induced fatigue in rats. The daily amounts of spontaneous running wheel activity decreased to about 40-60% of the preinjection level until day 9 with normal circadian rhythm, then gradually returned to the baseline level by day 14. Rats given a heat exposure (36 degrees C for 1 h) for the consecutive 3 days showed an increase in activity except for the first day. In the open field test, the total moving distance and the number of rearing of the poly I:C-injected rats decreased on day 1, but they were not different from the saline-injected group on day 7, suggesting that the poly I:C-induced fatigue on day 7 was not due to the peripheral problems such as muscle/joint pain, but involved the CNS. Quantitative analysis of mRNA levels using a real-time capillary reverse transcriptase-polymerase chain reaction (RT-PCR) method revealed that interferon-alpha (IFN-alpha) mRNA contents in the cortex, hippocampus, hypothalamic medial preoptic, paraventricular, and ventromedial nuclei were higher in the poly I:C group than those in the saline and heat-exposed groups on day 7, although the amount of interleukin-1 beta mRNA showed no differences. Serum adrenocorticotropic hormone and catecholamine levels were not significantly different between groups. The present results indicate that the prolonged fatigue induced by poly I:C, which is evaluated by the spontaneous running wheel activity, can be used as an animal model for the immunologically induced fatigue associated with viral infection, and suggest that brain IFN-alpha may play a role in this model.
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Affiliation(s)
- T Katafuchi
- Department of Integrative Physiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan.
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47
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Luellen BA, Miller DB, Chisnell AC, Murphy DL, O'Callaghan JP, Andrews AM. Neuronal and Astroglial Responses to the Serotonin and Norepinephrine Neurotoxin: 1-Methyl-4-(2′-aminophenyl)-1,2,3,6-tetrahydropyridine. J Pharmacol Exp Ther 2003; 307:923-31. [PMID: 14561848 DOI: 10.1124/jpet.103.055749] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
1-Methyl-4-(2'-aminophenyl)-1,2,3,6-tetrahydropyridine (2'-NH2-MPTP) causes long-term loss of forebrain serotonin (5-HT) and norepinephrine (NE) and consequently, is unlike 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and its other 2'-analogs that primarily deplete striatal dopamine (DA). In the present investigation into the acute effects of 2'-NH2-MPTP in mice, profound decreases in cortical and hippocampal 5-HT and NE to 10 to 40% of control were observed as early as 30 min post-treatment and lasted throughout the ensuing 21 days. Striatal DA was decreased to 60 to 80% of control during the first 48 h but returned to normal by 72 h. Reactive gliosis, which occurs in response to neurodegeneration was not evident by immunocytochemistry but was detected by enzyme-linked immunosorbent assay, where glial fibrillary acidic protein (GFAP) was increased to 130% of control in cortex, hippocampus, and brain stem 48 to 72 h post-treatment. To explore the possibility that 5-HT modulates the astrocytic response to injury, 2'-NH2-MPTP was used to damage 5-HT axons 2 weeks before administration of the potent DA neurotoxin 1-methyl-4-(2'-methylphenyl)-1,2,3,6-tetrahydropyridine (2'-CH3-MPTP). Despite a 90% decrement in striatal DA in 2'-NH2-MPTP/2'-CH3-MPTP-treated mice, increases in GFAP were attenuated compared to mice treated with 2'-CH3-MPTP alone. Thus, 2'-NH2-MPTP causes severe and immediate decrements in 5-HT and NE in frontal cortex and hippocampus, yet induces a modest GFAP response compared with other MPTP analogs that have their primary effect on DA. These results demonstrate the importance of obtaining quantitative assessments of GFAP to detect astroglial responses associated with selective damage to neurotransmitter systems with low-density innervation and suggest that serotonin may facilitate the astrocytic response to striatal injury.
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Affiliation(s)
- Beth A Luellen
- The Pennsylvania State University, 152 Davey Laboratory, University Park, PA 16802, USA
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48
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Reyes-Haro D, García-Alcocer G, Miledi R, García-Colunga J. Uptake of serotonin by adult rat corpus callosum is partially reduced by common antidepressants. J Neurosci Res 2003; 74:97-102. [PMID: 13130511 DOI: 10.1002/jnr.10724] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The corpus callosum (CC) is the main white matter tract involved in interhemispheric brain communication. We establish that uptake of [3H]5-hydroxytryptamine (5-HT) in CC is partially inhibited by some antidepressants. Slices of the adult rat CC had a high-affinity uptake of 5-HT. About 80% of this uptake was Na+ dependent, with a Michaelis-Menten constant, Km, of 420 +/- 80 nM and a rate of 5-HT uptake, Vmax, of 9.5 +/- 0.8 pmol/mg protein/min. The 5-HT uptake was reduced approximately 60% at pH 5 compared with that at pH 7. Fluoxetine (Prozac) inhibited only 43% of 5-HT uptake in a concentration-dependent manner, with an affinity constant, Ki, of 44.7 +/- 10.0 nM. We also studied the effects of other monoamine uptake inhibitors, all at 10 microM, and found that zimelidine, imipramine, and clomipramine inhibited 5-HT uptake in the CC by approximately 30-40%. The fluoxetine-insensitive 5-HT uptake was not altered by high concentrations of dopamine plus norepinephrine. The present data show that Na(+)-dependent 5-HT uptake occurs in the CC and optic nerve and that this uptake is partially sensitive to antidepressants and probably mediated by the serotonin transporter, which may be relevant during depression.
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Affiliation(s)
- Daniel Reyes-Haro
- Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Juriquilla, Querétaro, México
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49
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Kaufman MJ, Henry ME, Frederick BD, Hennen J, Villafuerte RA, Stoddard EP, Schmidt ME, Cohen BM, Renshaw PF. Selective serotonin reuptake inhibitor discontinuation syndrome is associated with a rostral anterior cingulate choline metabolite decrease: a proton magnetic resonance spectroscopic imaging study. Biol Psychiatry 2003; 54:534-9. [PMID: 12946882 DOI: 10.1016/s0006-3223(02)01828-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The selective serotonin reuptake inhibitor (SSRI) discontinuation syndrome (DS) is an important potential complication of treatment for major depression. We hypothesized that SSRI treatment discontinuation, resulting in change in clinical state, would be associated with reduced rostral anterior cingulate choline (Cho) metabolite ratios. Individuals with a DSM-III-R diagnosis of unipolar major depression who had been stabilized on paroxetine (n = 13) or fluoxetine (n = 13) were study subjects. They were monitored for change in clinical state (mood ratings, discontinuation symptoms) and underwent proton magnetic resonance spectroscopic imaging of the rostral anterior cingulate 3 days after medication substitution with active SSRI and placebo.Placebo-day Cho/Cre (choline/total creatine) metabolite ratios were decreased in four paroxetine and two fluoxetine subjects meeting DS criteria, as compared with asymptomatic subjects (Mann-Whitney z = -2.31, p =.021). Discontinuation syndrome is associated with a rostral anterior cingulate Cho/Cre metabolite ratio decrease that may reflect dynamics of rostral anterior cingulate function.
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Affiliation(s)
- Marc J Kaufman
- Brain Imaging Center, McLean Hospital, Harvard Medical School, Belmont, Massachusetts 02478, USA
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50
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Suchak SK, Baloyianni NV, Perkinton MS, Williams RJ, Meldrum BS, Rattray M. The 'glial' glutamate transporter, EAAT2 (Glt-1) accounts for high affinity glutamate uptake into adult rodent nerve endings. J Neurochem 2003; 84:522-32. [PMID: 12558972 DOI: 10.1046/j.1471-4159.2003.01553.x] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The excitatory amino acid transporters (EAAT) removes neurotransmitters glutamate and aspartate from the synaptic cleft. Most CNS glutamate uptake is mediated by EAAT2 into glia, though nerve terminals show evidence for uptake, through an unknown transporter. Reverse-transcriptase PCR identified the expression of EAAT1, EAAT2, EAAT3 and EAAT4 mRNAs in primary cultures of mouse cortical or striatal neurones. We have used synaptosomes and glial plasmalemmal vesicles (GPV) from adult mouse and rat CNS to identify the nerve terminal transporter. Western blotting showed detectable levels of the transporters EAAT1 (GLAST) and EAAT2 (Glt-1) in both synaptosomes and GPVs. Uptake of [3H]D-aspartate or [3H]L-glutamate into these preparations revealed sodium-dependent uptake in GPV and synaptosomes which was inhibited by a range of EAAT blockers: dihydrokainate, serine-o-sulfate, l-trans-2,4-pyrrolidine dicarboxylate (PDC) (+/-)-threo-3-methylglutamate and (2S,4R )-4-methylglutamate. The IC50 values found for these compounds suggested functional expression of the 'glial, transporter, EAAT2 in nerve terminals. Additionally blockade of the majority EAAT2 uptake sites with 100 micro m dihydrokainate, failed to unmask any functional non-EAAT2 uptake sites. The data presented in this study indicate that EAAT2 is the predominant nerve terminal glutamate transporter in the adult rodent CNS.
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Affiliation(s)
- Sachin K Suchak
- Biochemical Neuropharmacology Group, Centre for Neuroscience Research, GKT School of Biomedical Sciences, King's College London, United Kingdom
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