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Carvalho RKD, Rodrigues TC, Júnior WD, Mota GMP, Andersen ML, Mazaro E Costa R. Short- and long-term exposure to methamidophos impairs spermatogenesis in mice. Reprod Biol 2020; 20:357-364. [PMID: 32405287 PMCID: PMC7218378 DOI: 10.1016/j.repbio.2020.05.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 04/28/2020] [Accepted: 05/08/2020] [Indexed: 12/14/2022]
Abstract
Methamidophos (MET) is a pesticide that has toxic properties, including effects on fertility. This study aimed to assess the joint action of treatment time and exposure to methamidophos on the male reproductive system. MET was orally administered to adult male Swiss mice at a dose of 0.004 mg.kg−1 for 15 and 50 consecutive days. The following parameters were evaluated: weight of reproductive organs, spermatogenesis, sperm and Sertoli cell count, daily sperm production and sperm transit time. Short-term exposure to methamidophos induced a decrease in epididymal weight. The frequency of stages V–VI of spermatogenesis increased and the frequency of stage IX decreased. In the epididymis, sperm transit time (caput/corpus) was reduced and the relative sperm number (cauda) increased. Long-term exposure induced an increase in the frequencies of stages I–IV and V-VI and decreased the stages VII-VIII and IX. The number of Sertoli cells with evident nucleoli was reduced in both exposures. These results confirm the reproductive toxicity of MET.
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Affiliation(s)
- Renata Karine de Carvalho
- Department of Pharmacology, Laboratory of Physiology and Pharmacology of Reproduction, Universidade Federal de Goiás, Goiânia, GO, Brazil
| | - Thamyres Cunha Rodrigues
- Department of Pharmacology, Laboratory of Physiology and Pharmacology of Reproduction, Universidade Federal de Goiás, Goiânia, GO, Brazil
| | - Walter Dias Júnior
- Laboratory of Physiology and Toxicological Biochemistry, Universidade Estadual de Goiás, Ceres, GO, Brazil
| | | | - Monica Levy Andersen
- Department of Psychobiology, Universidade Federal de São Paulo, São Paulo, SP, Brazil
| | - Renata Mazaro E Costa
- Department of Pharmacology, Laboratory of Physiology and Pharmacology of Reproduction, Universidade Federal de Goiás, Goiânia, GO, Brazil.
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2
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Naito R, Kassai H, Sakai Y, Schönherr S, Fukaya M, Schwarzer C, Sakagami H, Nakao K, Aiba A, Ferraguti F. New Features on the Expression and Trafficking of mGluR1 Splice Variants Exposed by Two Novel Mutant Mouse Lines. Front Mol Neurosci 2018; 11:439. [PMID: 30559646 PMCID: PMC6287019 DOI: 10.3389/fnmol.2018.00439] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 11/13/2018] [Indexed: 01/08/2023] Open
Abstract
Metabotropic glutamate receptors (mGluRs) couple to G-proteins to modulate slow synaptic transmission via intracellular second messengers. The first cloned mGluR, mGluR1, regulates motor coordination, synaptic plasticity and synapse elimination. mGluR1 undergoes alternative splicing giving rise to four translated variants that differ in their intracellular C-terminal domains. Our current knowledge about mGluR1 relates almost entirely to the long mGluR1α isoform, whereas little is known about the other shorter variants. To study the expression of mGluR1γ, we have generated by means of the CRISPR/Cas9 system a new knock-in (KI) mouse line in which the C-terminus of this variant carries two short tags. Using this mouse line, we could establish that mGluR1γ is either untranslated or in amounts that are undetectable in the mouse cerebellum, indicating that only mGluR1α and mGluR1β are present and active at cerebellar synapses. The trafficking and function of mGluR1 appear strongly influenced by adaptor proteins such as long Homers that bind to the C-terminus of mGluR1α. We generated a second transgenic (Tg) mouse line in which mGluR1α carries a point mutation in its Homer binding domain and studied whether disruption of this interaction influenced mGluR1 subcellular localization at cerebellar parallel fiber (PF)-Purkinje cell (PC) synapses by means of the freeze-fracture replica immunolabeling technique. These Tg animals did not show any overt behavioral phenotype, and despite the typical mGluR1 perisynaptic distribution was not significantly changed, we observed a higher probability of intrasynaptic diffusion suggesting that long Homers regulate the lateral mobility of mGluR1. We extended our ultrastructural analysis to other mouse lines in which only one mGluR1 variant was reintroduced in PC of mGluR1-knock out (KO) mice. This work revealed that mGluR1α preferentially accumulates closer to the edge of the postsynaptic density (PSD), whereas mGluR1β has a less pronounced perijunctional distribution and, in the absence of mGluR1α, its trafficking to the plasma membrane is impaired with an accumulation in intracellular organelles. In conclusion, our study sets several firm points on largely disputed matters, namely expression of mGluR1γ and role of the C-terminal domain of mGluR1 splice variants on their perisynaptic clustering.
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Affiliation(s)
- Rika Naito
- Laboratory of Animal Resources, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.,Department of Pharmacology, Medical University of Innsbruck, Innsbruck, Austria
| | - Hidetoshi Kassai
- Laboratory of Animal Resources, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.,Division of Molecular Genetics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Yusuke Sakai
- Laboratory of Animal Resources, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Sabine Schönherr
- Department of Pharmacology, Medical University of Innsbruck, Innsbruck, Austria
| | - Masahiro Fukaya
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara, Japan
| | - Christoph Schwarzer
- Department of Pharmacology, Medical University of Innsbruck, Innsbruck, Austria
| | - Hiroyuki Sakagami
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara, Japan
| | - Kazuki Nakao
- Laboratory of Animal Resources, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.,Laboratory for Animal Resources and Genetic Engineering, RIKEN Center for Developmental Biology, Kobe, Japan
| | - Atsu Aiba
- Laboratory of Animal Resources, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.,Division of Molecular Genetics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Francesco Ferraguti
- Department of Pharmacology, Medical University of Innsbruck, Innsbruck, Austria
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3
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Lambert L, Dubayle D, Fafouri A, Herzog E, Csaba Z, Dournaud P, El Mestikawy S, Bernard V. Endocytosis of Activated Muscarinic m2 Receptor (m2R) in Live Mouse Hippocampal Neurons Occurs via a Clathrin-Dependent Pathway. Front Cell Neurosci 2018; 12:450. [PMID: 30555302 PMCID: PMC6283979 DOI: 10.3389/fncel.2018.00450] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 11/07/2018] [Indexed: 02/02/2023] Open
Abstract
Our aim was to examine the dynamics of the muscarinic m2 receptor (m2R), a G-protein coupled receptor (GPCR), after agonist activation in living hippocampal neurons, and especially clathrin dependency endocytosis. We have previously shown that the m2R undergoes agonist-induced internalization in vivo. However, the nature of the endocytotic pathway used by m2R after activation is still unknown in living neurons. Using live cell imaging and quantitative analyses, we have monitored the effect of stimulation on the fate of the membrane-bound m2R and on its redistribution in intraneuronal compartments. Shortly (6 min) after activation, m2R is internalized into clathrin immunopositive structures. Furthermore, after clathrin-dependent endocytosis, m2R associates with early and late endosomes and with subcellular organelles involved in degradation. Together, these results provide, for the first time, a description of m2R trafficking in living neurons and prove that m2R undergoes clathrin-dependent endocytosis before being degraded.
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Affiliation(s)
- Lisa Lambert
- Sorbonne Université, Université Pierre et Marie Curie UM 119 - CNRS UMR 8246 - INSERM U1130, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), Paris, France
| | - David Dubayle
- Sorbonne Université, Université Pierre et Marie Curie UM 119 - CNRS UMR 8246 - INSERM U1130, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), Paris, France.,Université Paris Descartes - CNRS UMR 8119, Centre de Neurophysique, Physiologie et Pathologie, Paris, France
| | - Assia Fafouri
- PROTECT, INSERM U1141, Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Etienne Herzog
- Sorbonne Université, Université Pierre et Marie Curie UM 119 - CNRS UMR 8246 - INSERM U1130, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), Paris, France.,Interdisciplinary Institute for Neuroscience, University Bordeaux, UMR 5297, Bordeaux, France.,Interdisciplinary Institute for Neuroscience, CNRS, UMR 5297, Bordeaux, France
| | - Zsolt Csaba
- PROTECT, INSERM U1141, Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Pascal Dournaud
- PROTECT, INSERM U1141, Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Salah El Mestikawy
- Sorbonne Université, Université Pierre et Marie Curie UM 119 - CNRS UMR 8246 - INSERM U1130, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), Paris, France.,Department of Psychiatry, Douglas Hospital Research Center, McGill University, Montréal, QC, Canada
| | - Véronique Bernard
- Sorbonne Université, Université Pierre et Marie Curie UM 119 - CNRS UMR 8246 - INSERM U1130, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), Paris, France
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4
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Shaffo FC, Grodzki AC, Fryer AD, Lein PJ. Mechanisms of organophosphorus pesticide toxicity in the context of airway hyperreactivity and asthma. Am J Physiol Lung Cell Mol Physiol 2018; 315:L485-L501. [PMID: 29952220 PMCID: PMC6230874 DOI: 10.1152/ajplung.00211.2018] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Revised: 06/15/2018] [Accepted: 06/18/2018] [Indexed: 12/14/2022] Open
Abstract
Numerous epidemiologic studies have identified an association between occupational exposures to organophosphorus pesticides (OPs) and asthma or asthmatic symptoms in adults. Emerging epidemiologic data suggest that environmentally relevant levels of OPs may also be linked to respiratory dysfunction in the general population and that in utero and/or early life exposures to environmental OPs may increase risk for childhood asthma. In support of a causal link between OPs and asthma, experimental evidence demonstrates that occupationally and environmentally relevant OP exposures induce bronchospasm and airway hyperreactivity in preclinical models. Mechanistic studies have identified blockade of autoinhibitory M2 muscarinic receptors on parasympathetic nerves that innervate airway smooth muscle as one mechanism by which OPs induce airway hyperreactivity, but significant questions remain regarding the mechanism(s) by which OPs cause neuronal M2 receptor dysfunction and, more generally, how OPs cause persistent asthma, especially after developmental exposures. The goals of this review are to 1) summarize current understanding of OPs in asthma; 2) discuss mechanisms of OP neurotoxicity and immunotoxicity that warrant consideration in the context of OP-induced airway hyperreactivity and asthma, specifically, inflammatory responses, oxidative stress, neural plasticity, and neurogenic inflammation; and 3) identify critical data gaps that need to be addressed in order to better protect adults and children against the harmful respiratory effects of low-level OP exposures.
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Affiliation(s)
- Frances C Shaffo
- Department of Molecular Biosciences, University of California , Davis, California
| | - Ana Cristina Grodzki
- Department of Molecular Biosciences, University of California , Davis, California
| | - Allison D Fryer
- Pulmonary Critical Care Medicine, Department of Medicine, Oregon Health & Science University , Portland, Oregon
| | - Pamela J Lein
- Department of Molecular Biosciences, University of California , Davis, California
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5
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DiCello JJ, Saito A, Rajasekhar P, Eriksson EM, McQuade RM, Nowell CJ, Sebastian BW, Fichna J, Veldhuis NA, Canals M, Bunnett NW, Carbone SE, Poole DP. Inflammation-associated changes in DOR expression and function in the mouse colon. Am J Physiol Gastrointest Liver Physiol 2018; 315:G544-G559. [PMID: 29927325 PMCID: PMC6230691 DOI: 10.1152/ajpgi.00025.2018] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Endogenous opioids activate opioid receptors (ORs) in the enteric nervous system to control intestinal motility and secretion. The μ-OR mediates the deleterious side effects of opioid analgesics, including constipation, respiratory depression, and addiction. Although the δ-OR (DOR) is a promising target for analgesia, the function and regulation of DOR in the colon are poorly understood. This study provides evidence that endogenous opioids activate DOR in myenteric neurons that may regulate colonic motility. The DOR agonists DADLE, deltorphin II, and SNC80 inhibited electrically evoked contractions and induced neurogenic contractions in the mouse colon. Electrical, chemical, and mechanical stimulation of the colon evoked the release of endogenous opioids, which stimulated endocytosis of DOR in the soma and proximal neurites of myenteric neurons of transgenic mice expressing DOR fused to enhanced green fluorescent protein. In contrast, DOR was not internalized in nerve fibers within the circular muscle. Administration of dextran sulfate sodium induced acute colitis, which was accompanied by DOR endocytosis and an increased density of DOR-positive nerve fibers within the circular muscle. The potency with which SNC80 inhibited neurogenic contractions was significantly enhanced in the inflamed colon. This study demonstrates that DOR-expressing neurons in the mouse colon can be activated by exogenous and endogenous opioids. Activated DOR traffics to endosomes and inhibits neurogenic motility of the colon. DOR signaling is enhanced during intestinal inflammation. This study demonstrates functional expression of DOR by myenteric neurons and supports the therapeutic targeting of DOR in the enteric nervous system. NEW & NOTEWORTHY DOR is activated during physiologically relevant reflex stimulation. Agonist-evoked DOR endocytosis is spatially and temporally regulated. A significant proportion of DOR is internalized in myenteric neurons during inflammation. The relative proportion of all myenteric neurons that expressed DOR and the overlap with the nNOS-positive population are increased in inflammation. DOR-specific innervation of the circular muscle is increased in inflammation, and this is consistent with enhanced responsiveness to the DOR agonist SNC80.
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Affiliation(s)
- Jesse J. DiCello
- 1Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia,7ARC Centre of Excellence in Bio-Nano Science and Technology, Parkville, Victoria, Australia
| | - Ayame Saito
- 1Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia,7ARC Centre of Excellence in Bio-Nano Science and Technology, Parkville, Victoria, Australia
| | - Pradeep Rajasekhar
- 1Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia,7ARC Centre of Excellence in Bio-Nano Science and Technology, Parkville, Victoria, Australia
| | - Emily M. Eriksson
- 2Division of Population Health and Immunity, Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia,3Division of Infection and Immunity, Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia,4Department of Medical Biology, University of Melbourne, Parkville, Victoria, Australia
| | - Rachel M. McQuade
- 1Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Cameron J. Nowell
- 1Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Benjamin W. Sebastian
- 1Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Jakub Fichna
- 5Department of Biochemistry, Faculty of Medicine, Medical University of Lodz, Lodz, Poland
| | - Nicholas A. Veldhuis
- 1Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia,6Department of Genetics, University of Melbourne, Parkville, Victoria, Australia,7ARC Centre of Excellence in Bio-Nano Science and Technology, Parkville, Victoria, Australia
| | - Meritxell Canals
- 1Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia,7ARC Centre of Excellence in Bio-Nano Science and Technology, Parkville, Victoria, Australia
| | - Nigel W. Bunnett
- 1Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia,7ARC Centre of Excellence in Bio-Nano Science and Technology, Parkville, Victoria, Australia,8Department of Pharmacology and Therapeutics University of Melbourne, Parkville, Victoria, Australia,9Department of Surgery and Pharmacology, Columbia University, New York, New York
| | - Simona E. Carbone
- 1Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia,7ARC Centre of Excellence in Bio-Nano Science and Technology, Parkville, Victoria, Australia
| | - Daniel P. Poole
- 1Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia,7ARC Centre of Excellence in Bio-Nano Science and Technology, Parkville, Victoria, Australia,10Department of Anatomy and Neuroscience, University of Melbourne, Parkville, Victoria, Australia
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6
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Kwak KA, Lee SP, Yang JY, Park YS. Current Perspectives regarding Stem Cell-Based Therapy for Alzheimer's Disease. Stem Cells Int 2018; 2018:6392986. [PMID: 29686714 PMCID: PMC5852851 DOI: 10.1155/2018/6392986] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2017] [Accepted: 01/15/2018] [Indexed: 02/07/2023] Open
Abstract
Alzheimer's disease (AD), a progressive neurodegenerative disorder featuring memory loss and cognitive impairment, is caused by synaptic failure and the excessive accumulation of misfolded proteins. Many unsuccessful attempts have been made to develop new small molecules or antibodies to intervene in the disease's pathogenesis. Stem cell-based therapies cast a new hope for AD treatment as a replacement or regeneration strategy. The results from recent preclinical studies regarding stem cell-based therapies are promising. Human clinical trials are now underway. However, a number of questions remain to be answered prior to safe and effective clinical translation. This review explores the pathophysiology of AD and summarizes the relevant stem cell research according to cell type. We also briefly summarize related clinical trials. Finally, future perspectives are discussed with regard to their clinical applications.
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Affiliation(s)
- Kyeong-Ah Kwak
- Department of Oral Anatomy, Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Republic of Korea
| | - Seung-Pyo Lee
- Department of Oral Anatomy, Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Republic of Korea
| | - Jin-Young Yang
- Department of Dental Hygiene, Daejeon Institute of Science and Technology, Daejeon, Republic of Korea
| | - Young-Seok Park
- Department of Oral Anatomy, Dental Research Institute, School of Dentistry, Seoul National University, Seoul, Republic of Korea
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7
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Tréfier A, Pellissier LP, Musnier A, Reiter E, Guillou F, Crépieux P. G Protein-Coupled Receptors As Regulators of Localized Translation: The Forgotten Pathway? Front Endocrinol (Lausanne) 2018; 9:17. [PMID: 29456523 PMCID: PMC5801404 DOI: 10.3389/fendo.2018.00017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 01/15/2018] [Indexed: 12/31/2022] Open
Abstract
G protein-coupled receptors (GPCRs) exert their physiological function by transducing a complex signaling network that coordinates gene expression and dictates the phenotype of highly differentiated cells. Much is known about the gene networks they transcriptionally regulate upon ligand exposure in a process that takes hours before a new protein is synthesized. However, far less is known about GPCR impact on the translational machinery and subsequent mRNA translation, although this gene regulation level alters the cell phenotype in a strikingly different timescale. In fact, mRNA translation is an early response kinetically connected to signaling events, hence it leads to the synthesis of a new protein within minutes following receptor activation. By these means, mRNA translation is responsive to subtle variations of the extracellular environment. In addition, when restricted to cell subcellular compartments, local mRNA translation contributes to cell micro-specialization, as observed in synaptic plasticity or in cell migration. The mechanisms that control where in the cell an mRNA is translated are starting to be deciphered. But how an extracellular signal triggers such local translation still deserves extensive investigations. With the advent of high-throughput data acquisition, it now becomes possible to review the current knowledge on the translatome that some GPCRs regulate, and how this information can be used to explore GPCR-controlled local translation of mRNAs.
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Affiliation(s)
- Aurélie Tréfier
- Biologie et Bioinformatique des Systèmes de Signalisation, INRA, UMR85, Physiologie de la Reproduction et des Comportements, Nouzilly, France
- CNRS, UMR7247, Nouzilly, France
- Université François Rabelais, Tours, France
- IFCE, Nouzilly, France
| | - Lucie P. Pellissier
- Déficit de Récompense, GPCR et sociabilité, INRA, UMR85, Physiologie de la Reproduction et des Comportements, Nouzilly, France
- CNRS, UMR7247, Nouzilly, France
- Université François Rabelais, Tours, France
- IFCE, Nouzilly, France
| | - Astrid Musnier
- Biologie et Bioinformatique des Systèmes de Signalisation, INRA, UMR85, Physiologie de la Reproduction et des Comportements, Nouzilly, France
- CNRS, UMR7247, Nouzilly, France
- Université François Rabelais, Tours, France
- IFCE, Nouzilly, France
| | - Eric Reiter
- Biologie et Bioinformatique des Systèmes de Signalisation, INRA, UMR85, Physiologie de la Reproduction et des Comportements, Nouzilly, France
- CNRS, UMR7247, Nouzilly, France
- Université François Rabelais, Tours, France
- IFCE, Nouzilly, France
| | - Florian Guillou
- Plasticité Génomique et Expression Phénotypique, INRA, UMR85, Physiologie de la Reproduction et des Comportements, Nouzilly, France
- CNRS, UMR7247, Nouzilly, France
- Université François Rabelais, Tours, France
- IFCE, Nouzilly, France
| | - Pascale Crépieux
- Biologie et Bioinformatique des Systèmes de Signalisation, INRA, UMR85, Physiologie de la Reproduction et des Comportements, Nouzilly, France
- CNRS, UMR7247, Nouzilly, France
- Université François Rabelais, Tours, France
- IFCE, Nouzilly, France
- *Correspondence: Pascale Crépieux,
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8
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Janickova H, Prado VF, Prado MAM, El Mestikawy S, Bernard V. Vesicular acetylcholine transporter (VAChT) over-expression induces major modifications of striatal cholinergic interneuron morphology and function. J Neurochem 2017. [DOI: 10.1111/jnc.14105] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Helena Janickova
- Department of Physiology and Pharmacology and Department of Anatomy & Cell Biology; Robarts Research Institute; Molecular Medicine Laboratories; The University of Western Ontario; London Ontario Canada
| | - Vania F. Prado
- Department of Physiology and Pharmacology and Department of Anatomy & Cell Biology; Robarts Research Institute; Molecular Medicine Laboratories; The University of Western Ontario; London Ontario Canada
| | - Marco A. M. Prado
- Department of Physiology and Pharmacology and Department of Anatomy & Cell Biology; Robarts Research Institute; Molecular Medicine Laboratories; The University of Western Ontario; London Ontario Canada
| | - Salah El Mestikawy
- Sorbonne Universités; Université Pierre et Marie Curie UM 119 - CNRS UMR 8246 - INSERM U1130; Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS); Paris France
- Department of Psychiatry; Douglas Mental Health University Institute; McGill University; Montreal Canada
| | - Véronique Bernard
- Sorbonne Universités; Université Pierre et Marie Curie UM 119 - CNRS UMR 8246 - INSERM U1130; Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS); Paris France
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9
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Huang YH, Su YS, Chang CJ, Sun WH. Heteromerization of G2A and OGR1 enhances proton sensitivity and proton-induced calcium signals. J Recept Signal Transduct Res 2016; 36:633-644. [PMID: 27049592 DOI: 10.3109/10799893.2016.1155064] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Proton-sensing G-protein-coupled receptors (GPCRs; OGR1, GPR4, G2A, TDAG8), with full activation at pH 6.4 ∼ 6.8, are important to pH homeostasis, immune responses and acid-induced pain. Although G2A mediates the G13-Rho pathway in response to acid, whether G2A activates Gs, Gi or Gq proteins remains debated. In this study, we examined the response of this fluorescence protein-tagged OGR1 family to acid stimulation in HEK293T cells. G2A did not generate detectable intracellular calcium or cAMP signals or show apparent receptor redistribution with moderate acid (pH ≥ 6.0) stimulation but reduced cAMP accumulation under strong acid stimulation (pH ≤ 5.5). Surprisingly, coexpression of OGR1- and G2A-enhanced proton sensitivity and proton-induced calcium signals. This alteration is attributed to oligomerization of OGR1 and G2A. The oligomeric potential locates receptors at a specific site, which leads to enhanced proton-induced calcium signals through channels.
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Affiliation(s)
- Ya-Han Huang
- a Department of Life Sciences , National Central University , Jhongli , Taiwan and
| | - Yeu-Shiuan Su
- a Department of Life Sciences , National Central University , Jhongli , Taiwan and
| | - Chung-Jen Chang
- a Department of Life Sciences , National Central University , Jhongli , Taiwan and
| | - Wei-Hsin Sun
- a Department of Life Sciences , National Central University , Jhongli , Taiwan and.,b Center for Biotechnology and Biomedical Engineering, National Central University , Jhongli , Taiwan
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10
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Mohr F, Krejci E, Zimmermann M, Klein J. Dysfunctional Presynaptic M2 Receptors in the Presence of Chronically High Acetylcholine Levels: Data from the PRiMA Knockout Mouse. PLoS One 2015; 10:e0141136. [PMID: 26506622 PMCID: PMC4624712 DOI: 10.1371/journal.pone.0141136] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Accepted: 10/05/2015] [Indexed: 12/31/2022] Open
Abstract
The muscarinic M2 receptor (M2R) acts as a negative feedback regulator in central cholinergic systems. Activation of the M2 receptor limits acetylcholine (ACh) release, especially when ACh levels are increased because acetylcholinesterase (AChE) activity is acutely inhibited. Chronically high ACh levels in the extracellular space, however, were reported to down-regulate M2R to various degrees. In the present study, we used the PRiMA knockout mouse which develops severely reduced AChE activity postnatally to investigate ACh release, and we used microdialysis to investigate whether the function of M2R to reduce ACh release in vivo was impaired in adult PRiMA knockout mice. We first show that striatal and hippocampal ACh levels, while strongly increased, still respond to AChE inhibitors. Infusion or injection of oxotremorine, a muscarinic M2 agonist, reduced ACh levels in wild-type mice but did not significantly affect ACh levels in PRiMA knockout mice or in wild-type mice in which ACh levels were artificially increased by infusion of neostigmine. Scopolamine, a muscarinic antagonist, increased ACh levels in wild-type mice receiving neostigmine, but not in wild-type mice or in PRiMA knockout mice. These results demonstrate that M2R are dysfunctional and do not affect ACh levels in PRiMA knockout mice, likely because of down-regulation and/or loss of receptor-effector coupling. Remarkably, this loss of function does not affect cognitive functions in PRiMA knockout mice. Our results are discussed in the context of AChE inhibitor therapy as used in dementia.
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Affiliation(s)
- Franziska Mohr
- Department of Pharmacology, School of Pharmacy, Goethe University, Frankfurt am Main, Germany
| | - Eric Krejci
- Centre d'Etude de la Sensorimotricité, Université Paris Descartes, CNRS UMR 8194, Paris, France
| | - Martina Zimmermann
- Department of Pharmacology, School of Pharmacy, Goethe University, Frankfurt am Main, Germany; Centre for the Humanities and Health, Department of English, King´s College, London, United Kingdom
| | - Jochen Klein
- Department of Pharmacology, School of Pharmacy, Goethe University, Frankfurt am Main, Germany
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Pradhan AA, Tawfik VL, Tipton AF, Scherrer G. In vivo techniques to investigate the internalization profile of opioid receptors. Methods Mol Biol 2015; 1230:87-104. [PMID: 25293318 DOI: 10.1007/978-1-4939-1708-2_7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
G-protein-coupled receptors (GPCRs) regulate a remarkable diversity of biological functions, and are thus often targeted for drug therapies. Receptor internalization is commonly observed following agonist binding and activation. Receptor trafficking events have been well characterized in cell systems, but the in vivo significance of GPCR internalization is still poorly understood. To address this issue, we have developed an innovative knock-in mouse model, where an opioid receptor is directly visible in vivo. These knockin mice express functional fluorescent delta opioid receptors (DOR-eGFP) in place of the endogenous receptor, and these receptors are expressed at physiological levels within their native environment. DOR-eGFP mice have proven to be an extraordinary tool in studying receptor neuroanatomy, real-time receptor trafficking in live neurons, and in vivo receptor internalization. We have used this animal model to determine the relationship between receptor trafficking in neurons and receptor function at a behavioral level. Here, we describe in detail the construction and characterization of this knockin mouse. We also outline how to use these mice to examine the behavioral consequences of agonist-specific trafficking at the delta opioid receptor. These techniques are potentially applicable to any GPCR, and highlight the powerful nature of this imaging tool.
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Affiliation(s)
- Amynah A Pradhan
- Department of Psychiatry, University of Illinois at Chicago, 1601 W Taylor Street, Chicago, IL, 60612, USA,
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Ong EW, Xue L, Olmstead MC, Cahill CM. Prolonged morphine treatment alters δ opioid receptor post-internalization trafficking. Br J Pharmacol 2014; 172:615-29. [PMID: 24819092 PMCID: PMC4292973 DOI: 10.1111/bph.12761] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2013] [Revised: 04/15/2014] [Accepted: 04/29/2014] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND AND PURPOSE The δ opioid receptor (DOP receptor) undergoes internalization both constitutively and in response to agonists. Previous work has shown that DOP receptors traffic from intracellular compartments to neuronal cell membranes following prolonged morphine treatment. Here, we examined the effects of prolonged morphine treatment on the post-internalization trafficking of DOP receptors. EXPERIMENTAL APPROACH Using primary cultures of dorsal root ganglia neurons, we measured the co-localization of endogenous DOP receptors with post-endocytic compartments following both prolonged and acute agonist treatments. KEY RESULTS A departure from the constitutive trafficking pathway was observed following acute DOP receptor agonist-induced internalization by deltorphin II. That is, the DOP receptor underwent distinct agonist-induced post-endocytic sorting. Following prolonged morphine treatment, constitutive DOP receptor trafficking was augmented. SNC80 following prolonged morphine treatment also caused non-constitutive DOP receptor agonist-induced post-endocytic sorting. The μ opioid receptor (MOP receptor) agonist DAMGO induced DOP receptor internalization and trafficking following prolonged morphine treatment. Finally, all of the alterations to DOP receptor trafficking induced by both DOP and MOP receptor agonists were inhibited or absent when those agonists were co-administered with a DOP receptor antagonist, SDM-25N. CONCLUSIONS AND IMPLICATIONS The results support the hypothesis that prolonged morphine treatment induces the formation of MOP–DOP receptor interactions and subsequent augmentation of the available cell surface DOP receptors, at least some of which are in the form of a MOP/DOP receptor species. The pharmacology and trafficking of this species appear to be unique compared to those of its individual constituents. LINKED ARTICLES This article is part of a themed section on Opioids: New Pathways to Functional Selectivity. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2015.172.issue-2
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Affiliation(s)
- E W Ong
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, Canada; Department of Anaesthesiology and Perioperative Care, University of California, Irvine, CA, USA
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Csaba Z, Krejci E, Bernard V. Postsynaptic muscarinic m2 receptors at cholinergic and glutamatergic synapses of mouse brainstem motoneurons. J Comp Neurol 2013. [PMID: 23184757 DOI: 10.1002/cne.23268] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
In many brain areas, few cholinergic synapses are identified. Acetylcholine is released into the extracellular space and acts through diffuse transmission. Motoneurons, however, are contacted by numerous cholinergic terminals, indicating synaptic cholinergic transmission on them. The muscarinic m2 receptor is the major acetylcholine receptor subtype of motoneurons; therefore, we analyzed the localization of the m2 receptor in correlation with synapses by electron microscopic immunohistochemistry in the mouse trigeminal, facial, and hypoglossal motor nuclei. In all nuclei, m2 receptors were localized at the membrane of motoneuronal perikarya and dendrites. The m2 receptors were concentrated at cholinergic synapses located on the perikarya and most proximal dendrites. However, m2 receptors at cholinergic synapses represented only a minority (<10%) of surface m2 receptors. The m2 receptors were also enriched at glutamatergic synapses in both motoneuronal perikarya and dendrites. A relatively large proportion (20-30%) of plasma membrane-associated m2 receptors were located at glutamatergic synapses. In conclusion, the effect of acetylcholine on motoneuron populations might be mediated through a synaptic as well as diffuse type of transmission.
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Affiliation(s)
- Zsolt Csaba
- Université Paris Descartes, 75006 Paris, France.
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Reassessment of the Role of the Central Cholinergic System. J Mol Neurosci 2013; 53:352-8. [DOI: 10.1007/s12031-013-0164-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Accepted: 10/24/2013] [Indexed: 12/18/2022]
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15
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Garzón M, Pickel VM. Somatodendritic targeting of M5 muscarinic receptor in the rat ventral tegmental area: implications for mesolimbic dopamine transmission. J Comp Neurol 2013; 521:2927-46. [PMID: 23504804 PMCID: PMC4038040 DOI: 10.1002/cne.23323] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Revised: 01/29/2013] [Accepted: 02/26/2013] [Indexed: 11/10/2022]
Abstract
Muscarinic modulation of mesolimbic dopaminergic neurons in the ventral tegmental area (VTA) plays an important role in reward, potentially mediated through the M5 muscarinic acetylcholine receptor (M5R). However, the key sites for M5R-mediated control of dopamine neurons within this region are still unknown. To address this question we examined the electron microscopic immunocytochemical localization of antipeptide antisera against M5R and the plasmalemmal dopamine transporter (DAT) in single sections through the rat VTA. M5R was located mainly to VTA somatodendritic profiles (71%; n = 627), at least one-third (33.2%; n = 208) of which also contained DAT. The M5R immunoreactivity was distributed along cytoplasmic tubulovesicular endomembrane systems in somata and large dendrites, but was more often located at plasmalemmal sites in small dendrites, the majority of which did not express DAT. The M5R-immunoreactive dendrites received a balanced input from unlabeled terminals forming either asymmetric or symmetric synapses. Compared with dendrites, M5R was less often seen in axon terminals, comprising only 10.8% (n = 102) of the total M5R-labeled profiles. These terminals were usually presynaptic to unlabeled dendrites, suggesting that M5R activation can indirectly modulate non-DAT-containing dendrites through presynaptic mechanisms. Our results provide the first ultrastructural evidence that in the VTA, M5R has a subcellular location conducive to major involvement in postsynaptic signaling in many dendrites, only some of which express DAT. These findings suggest that cognitive and rewarding effects ascribed to muscarinic activation in the VTA can primarily be credited to M5R activation at postsynaptic plasma membranes distinct from dopamine transport.
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Affiliation(s)
- Miguel Garzón
- Department of Anatomy, Histology, and Neuroscience, Medical School, Universidad Autónoma de Madrid (UAM), Madrid, 28029, Spain.
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Farar V, Hrabovska A, Krejci E, Myslivecek J. Developmental adaptation of central nervous system to extremely high acetylcholine levels. PLoS One 2013; 8:e68265. [PMID: 23861875 PMCID: PMC3701655 DOI: 10.1371/journal.pone.0068265] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Accepted: 05/31/2013] [Indexed: 11/19/2022] Open
Abstract
Acetylcholinesterase (AChE) is a key enzyme in termination of fast cholinergic transmission. In brain, acetylcholine (ACh) is produced by cholinergic neurons and released in extracellular space where it is cleaved by AChE anchored by protein PRiMA. Recently, we showed that the lack of AChE in brain of PRiMA knock-out (KO) mouse increased ACh levels 200-300 times. The PRiMA KO mice adapt nearly completely by the reduction of muscarinic receptor (MR) density. Here we investigated changes in MR density, AChE, butyrylcholinesterase (BChE) activity in brain in order to determine developmental period responsible for such adaptation. Brains were studied at embryonal day 18.5 and postnatal days (pd) 0, 9, 30, 120, and 425. We found that the AChE activity in PRiMA KO mice remained very low at all studied ages while in wild type (WT) mice it gradually increased till pd120. BChE activity in WT mice gradually decreased until pd9 and then increased by pd120, it continually decreased in KO mice till pd30 and remained unchanged thereafter. MR number increased in WT mice till pd120 and then became stable. Similarly, MR increased in PRiMA KO mice till pd30 and then remained stable, but the maximal level reached is approximately 50% of WT mice. Therefore, we provide the evidence that adaptive changes in MR happen up to pd30. This is new phenomenon that could contribute to the explanation of survival and nearly unchanged phenotype of PRiMA KO mice.
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Affiliation(s)
- Vladimir Farar
- 1st Faculty of Medicine, Institute of Physiology, Charles University, Prague, Czech Republic
- Centre d’Etude de la Sensorimotricité, Université Paris Descartes, CNRS UMR 8194, Paris, France
| | - Anna Hrabovska
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Comenius University, Bratislava, Slovakia
| | - Eric Krejci
- Centre d’Etude de la Sensorimotricité, Université Paris Descartes, CNRS UMR 8194, Paris, France
| | - Jaromir Myslivecek
- 1st Faculty of Medicine, Institute of Physiology, Charles University, Prague, Czech Republic
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Simon AC, Loverdo C, Gaffuri AL, Urbanski M, Ladarre D, Carrel D, Rivals I, Leterrier C, Benichou O, Dournaud P, Szabo B, Voituriez R, Lenkei Z. Activation-dependent plasticity of polarized GPCR distribution on the neuronal surface. J Mol Cell Biol 2013; 5:250-65. [PMID: 23585691 DOI: 10.1093/jmcb/mjt014] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Directionality of information flow through neuronal networks is sustained at cellular level by polarized neurons. However, specific targeting or anchoring motifs responsible for polarized distribution on the neuronal surface have only been identified for a few neuronal G-protein-coupled receptors (GPCRs). Here, through mutational and pharmacological modifications of the conformational state of two model GPCRs, the axonal CB1R cannabinoid and the somatodendritic SSTR2 somatostatin receptors, we show important conformation-dependent variations in polarized distribution. The underlying mechanisms include lower efficiency of conformation-dependent GPCR endocytosis in axons, compared with dendrites, particularly at moderate activation levels, as well as endocytosis-dependent transcytotic delivery of GPCRs from the somatodendritic domain to distal axonal portions, shown by using compartmentalized microfluidic devices. Kinetic modeling predicted that GPCR distribution polarity is highly regulated by steady-state endocytosis, which is conformation dependent and is able to regulate the relative amount of GPCRs targeted to axons and that axonally polarized distribution is an intermediary phenotype that appears at moderate basal activation levels. Indeed, we experimentally show that gradual changes in basal activation-dependent endocytosis lead to highly correlated shifts of polarized GPCR distribution on the neuronal surface, which can even result in a fully reversed polarized distribution of naturally somatodendritic or axonal GPCRs. In conclusion, polarized distribution of neuronal GPCRs may have a pharmacologically controllable component, which, in the absence of dominant targeting motifs, could even represent the principal regulator of sub-neuronal distribution. Consequently, chronic modifications of basal GPCR activation by therapeutic or abused drugs may lead to previously unanticipated changes in brain function through perturbation of polarized GPCR distribution on the neuronal surface.
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Affiliation(s)
- Anne C Simon
- Laboratoire de Neurobiologie, CNRS UMR7637, ESPCI-ParisTech, 10 Rue Vauquelin, Paris 75005, France
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Porras G, Berthet A, Dehay B, Li Q, Ladepeche L, Normand E, Dovero S, Martinez A, Doudnikoff E, Martin-Négrier ML, Chuan Q, Bloch B, Choquet D, Boué-Grabot E, Groc L, Bezard E. PSD-95 expression controls L-DOPA dyskinesia through dopamine D1 receptor trafficking. J Clin Invest 2012; 122:3977-89. [PMID: 23041629 DOI: 10.1172/jci59426] [Citation(s) in RCA: 102] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Accepted: 08/16/2012] [Indexed: 11/17/2022] Open
Abstract
L-DOPA-induced dyskinesia (LID), a detrimental consequence of dopamine replacement therapy for Parkinson's disease, is associated with an alteration in dopamine D1 receptor (D1R) and glutamate receptor interactions. We hypothesized that the synaptic scaffolding protein PSD-95 plays a pivotal role in this process, as it interacts with D1R, regulates its trafficking and function, and is overexpressed in LID. Here, we demonstrate in rat and macaque models that disrupting the interaction between D1R and PSD-95 in the striatum reduces LID development and severity. Single quantum dot imaging revealed that this benefit was achieved primarily by destabilizing D1R localization, via increased lateral diffusion followed by increased internalization and diminished surface expression. These findings indicate that altering D1R trafficking via synapse-associated scaffolding proteins may be useful in the treatment of dyskinesia in Parkinson's patients.
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Affiliation(s)
- Gregory Porras
- Université de Bordeaux, Institut des Maladies Neurodégénératives, Bordeaux, France
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Zimmer L, Luxen A. PET radiotracers for molecular imaging in the brain: Past, present and future. Neuroimage 2012; 61:363-70. [DOI: 10.1016/j.neuroimage.2011.12.037] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Accepted: 12/15/2011] [Indexed: 12/22/2022] Open
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Pradhan AA, Befort K, Nozaki C, Gavériaux-Ruff C, Kieffer BL. The delta opioid receptor: an evolving target for the treatment of brain disorders. Trends Pharmacol Sci 2011; 32:581-90. [PMID: 21925742 DOI: 10.1016/j.tips.2011.06.008] [Citation(s) in RCA: 218] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Revised: 06/18/2011] [Accepted: 06/21/2011] [Indexed: 12/14/2022]
Abstract
Compared to the better-known mu opioid receptor, delta opioid receptors have been relatively understudied. However, the development of highly selective delta opioid agonists and the availability of genetic mouse models have extended our knowledge of delta opioid receptors in vivo. Here we review recent developments in the characterization of delta opioid receptor biology and aspects of delta opioid receptor function that have potential for therapeutic targeting. Preclinical data have confirmed that delta opioid receptor activation reduces persistent pain and improves negative emotional states; clinical trials have been initiated to assess the effectiveness of delta opioid agonists in chronic pain and depression. Furthermore, a possible role for these receptors in neuroprotection is being investigated. The usefulness of targeting delta opioid receptors in drug abuse remains open and a role for these receptors in impulse control disorders is emerging. Finally, the recent demonstration of biased agonism at the delta opioid receptor in vivo opens novel perspectives towards targeting specific therapeutic effects through drug design.
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Affiliation(s)
- Amynah A Pradhan
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique/Institut National de la Santé et de la Recherche Médicale/Université de Strasbourg, 1 Rue Laurent Fries, 67404 Illkirch, France
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Abstract
Molecular in vivo neuroimaging techniques can be used to measure regional changes in endogenous neurotransmitters, evoked by challenges that alter synaptic neurotransmitter concentration. This technique has most successfully been applied to the study of endogenous dopamine release using positron emission tomography, but has not yet been adequately extended to other neurotransmitter systems. This review focuses on how the technique has been applied to the study of the 5-hydroxytryptamine (5-HT) system. The principles behind visualising fluctuations in neurotransmitters are introduced, with reference to the dopaminergic system. Studies that aim to image acute, endogenous 5-HT release or depletion at 5-HT receptor targets are summarised, with particular attention to studies in humans. Radiotracers targeting the 5-HT(1A), 5-HT(2A), and 5-HT(4) receptors and the serotonin reuptake transporter have been explored for their sensitivity to 5-HT fluctuations, but with mixed outcomes; tracers for these targets cannot reliably image endogenous 5-HT in humans. Shortcomings in our basic knowledge of the mechanisms underlying changes in binding potential are addressed, and suggestions are made as to how the selection of targets, radiotracers, challenge paradigms, and experimental design might be optimised to improve our chances of successfully imaging endogenous neurotransmitters in the future.
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Proskocil BJ, Bruun DA, Thompson CM, Fryer AD, Lein PJ. Organophosphorus pesticides decrease M2 muscarinic receptor function in guinea pig airway nerves via indirect mechanisms. PLoS One 2010; 5:e10562. [PMID: 20479945 PMCID: PMC2866713 DOI: 10.1371/journal.pone.0010562] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2010] [Accepted: 04/16/2010] [Indexed: 12/28/2022] Open
Abstract
Background Epidemiological studies link organophosphorus pesticide (OP) exposures to asthma, and we have shown that the OPs chlorpyrifos, diazinon and parathion cause airway hyperreactivity in guinea pigs 24 hr after a single subcutaneous injection. OP-induced airway hyperreactivity involves M2 muscarinic receptor dysfunction on airway nerves independent of acetylcholinesterase (AChE) inhibition, but how OPs inhibit neuronal M2 receptors in airways is not known. In the central nervous system, OPs interact directly with neurons to alter muscarinic receptor function or expression; therefore, in this study we tested whether the OP parathion or its oxon metabolite, paraoxon, might decrease M2 receptor function on peripheral neurons via similar direct mechanisms. Methodology/Principal Findings Intravenous administration of paraoxon, but not parathion, caused acute frequency-dependent potentiation of vagally-induced bronchoconstriction and increased electrical field stimulation (EFS)-induced contractions in isolated trachea independent of AChE inhibition. However, paraoxon had no effect on vagally-induced bradycardia in intact guinea pigs or EFS-induced contractions in isolated ileum, suggesting mechanisms other than pharmacologic antagonism of M2 receptors. Paraoxon did not alter M2 receptor expression in cultured cells at the mRNA or protein level as determined by quantitative RT-PCR and radio-ligand binding assays, respectively. Additionally, a biotin-labeled fluorophosphonate, which was used as a probe to identify molecular targets phosphorylated by OPs, did not phosphorylate proteins in guinea pig cardiac membranes that were recognized by M2 receptor antibodies. Conclusions/Significance These data indicate that neither direct pharmacologic antagonism nor downregulated expression of M2 receptors contributes to OP inhibition of M2 function in airway nerves, adding to the growing evidence of non-cholinergic mechanisms of OP neurotoxicity.
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Affiliation(s)
- Becky J. Proskocil
- Division of Pulmonary and Critical Care Medicine, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Donald A. Bruun
- Department of Molecular Biosciences, University of California Davis, Davis, California, United States of America
| | - Charles M. Thompson
- Center for Structural and Functional Neuroscience, Department of Biomedical and Pharmaceutical Sciences, University of Montana, Missoula, Montana, United States of America
| | - Allison D. Fryer
- Division of Pulmonary and Critical Care Medicine, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Pamela J. Lein
- Department of Molecular Biosciences, University of California Davis, Davis, California, United States of America
- * E-mail:
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Kuenzel W, Jurkevich A. Molecular neuroendocrine events during stress in poultry. Poult Sci 2010; 89:832-40. [DOI: 10.3382/ps.2009-00376] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Massart R, Guilloux JP, Mignon V, Sokoloff P, Diaz J. Striatal GPR88 expression is confined to the whole projection neuron population and is regulated by dopaminergic and glutamatergic afferents. Eur J Neurosci 2009; 30:397-414. [PMID: 19656174 DOI: 10.1111/j.1460-9568.2009.06842.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
GPR88, an orphan G protein-coupled receptor, was designated Strg/GPR88 for striatum-specific G protein-coupled receptor (K. Mizushima et al. (2000)Genomics, 69, 314-321). In this study, we focused on striatal GPR88 protein localization using a polyclonal antibody. We established that the distribution of immunoreactivity in rat brain matched that of GPR88 transcripts and provided evidence for its exclusive neuronal expression. GPR88 protein is abundant throughout the striatum of rat and primate, with expression limited to the two subsets of striatal projection medium spiny neurons (MSNs) expressing preprotachykinin-substance P or preproenkephalin mRNAs. Ultrastructural immunolabelling revealed the GPR88 concentration at post-synaptic sites along the somatodendritic compartments of MSNs, with pronounced preference for dendrites and dendritic spines. The GPR88-rich expression, in both striatal output pathways, designates this receptor as a potential therapeutic target for diseases involving dysfunction of the basal ganglia, such as Parkinson's disease. Hence, we investigated changes of GPR88 expression in a model of Parkinson's disease (unilateral 6-hydroxydopamine-lesioned rats) following repeated L-DOPA treatment. In dopamine-depleted striatum, GPR88 expression was differentially regulated, i.e. decreased in striatopallidal and increased in striatonigral MSNs. L-DOPA treatment led to a normalization of GPR88 levels through dopamine D1 and D2 receptor-mediated mechanisms in striatopallidal and striatonigral MSNs, respectively. Moreover, the removal of corticostriatal inputs, by ibotenate infusion, downregulated GPR88 in striatopallidal MSNs. These findings provide the first evidence that GPR88 is confined to striatal MSNs and indicate that L-DOPA-mediated behavioural effects in hemiparkinsonian rats may involve normalization of striatal GPR88 levels probably through dopamine receptor-mediated mechanisms and modulations of corticostriatal pathway activity.
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Affiliation(s)
- Renaud Massart
- INSERM U-573, Neurobiologie et Pharmacologie Moléculaire, Paris, France
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Nefti W, Chaumontet C, Fromentin G, Tomé D, Darcel N. A high-fat diet attenuates the central response to within-meal satiation signals and modifies the receptor expression of vagal afferents in mice. Am J Physiol Regul Integr Comp Physiol 2009; 296:R1681-6. [DOI: 10.1152/ajpregu.90733.2008] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
During digestion, macronutrients are sensed within the small intestine. This sensory process is dependent upon the action of gut mediators, such as cholecystokinin (CCK) or serotonin (5-HT), on vagal afferents that, in turn, convey peripheral information to the brain to influence the control of food intake. Recent studies have suggested that dietary conditions alter vagal sensitivity to CCK and 5-HT. This phenomenon may be of importance to the onset of eating disorders. The aim of the present study was thus to investigate the effects of subjecting mice to 15 days of either an HF diet (30% fat, 54% carbohydrate) or an NF diet (10% fat, 74% carbohydrate) on 1) daily and short-term food intake, 2) vagal sensitivity to peripheral anorectic factors and macronutrient loads, and 3) vagal afferent neuron receptor expression. The results indicated that compared with an NF diet, and while increasing food intake and body weight gain, an HF diet altered the short-term response to CCK-8 and intragastric macronutrient loads, while decreasing vagal activation by CCK-8 and modifying the receptor expression of vagal neurons. These findings, therefore, suggest that dietary intervention effect on food intake could be linked to changes in vagal afferent receptor profiles.
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Pharmacological analysis demonstrates dramatic alteration of D1 dopamine receptor neuronal distribution in the rat analog of L-DOPA-induced dyskinesia. J Neurosci 2009; 29:4829-35. [PMID: 19369551 DOI: 10.1523/jneurosci.5884-08.2009] [Citation(s) in RCA: 120] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We have associated behavioral, pharmacological, and quantitative immunohistochemical study in a rat analog of l-DOPA-induced dyskinesia to understand whether alterations in dopamine receptor fate in striatal neurons may be involved in mechanisms leading to movement abnormalities. Detailed analysis at the ultrastructural level demonstrates specific alterations of dopamine D(1) receptor (D(1)R) subcellular localization in striatal medium spiny neurons in l-DOPA-treated 6-hydroxydopamine-lesioned rats with abnormal involuntary movements (AIMs). This includes exaggerated D(1)R expression at the plasma membrane. However, D(1)R retains ability of internalization, as a challenge with the potent D(1)R agonist SKF-82958 induces a strong decrease of labeling at membrane in animals with AIMs. Since a functional cross talk between D(1)R and D(3)R has been suggested, we hypothesized that their coactivation by dopamine derived from l-DOPA might anchor D(1)R at the membrane. Accordingly, cotreatment with l-DOPA and the D(3)R antagonist ST 198 restores normal level of membrane-bound D(1)R. Together, these results demonstrate that AIMs are related to abnormal D(1)R localization at the membrane and intraneuronal trafficking dysregulation, and suggest that strategies aiming at disrupting the D(1)R-D(3)R cross talk might reduce l-DOPA-induced dyskinesia by reducing D(1)R availability at the membrane.
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Targeting of acetylcholinesterase in neurons in vivo: a dual processing function for the proline-rich membrane anchor subunit and the attachment domain on the catalytic subunit. J Neurosci 2009; 29:4519-30. [PMID: 19357277 DOI: 10.1523/jneurosci.3863-08.2009] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Acetylcholinesterase (AChE) accumulates on axonal varicosities and is primarily found as tetramers associated with a proline-rich membrane anchor (PRiMA). PRiMA is a small transmembrane protein that efficiently transforms secreted AChE to an enzyme anchored on the outer cell surface. Surprisingly, in the striatum of the PRiMA knock-out mouse, despite a normal level of AChE mRNA, we find only 2-3% of wild type AChE activity, with the residual AChE localized in the endoplasmic reticulum, demonstrating that PRiMA in vivo is necessary for intracellular processing of AChE in neurons. Moreover, deletion of the retention signal of the AChE catalytic subunit in mice, which is the domain of interaction with PRiMA, does not restore AChE activity in the striatum, establishing that PRiMA is necessary to target and/or to stabilize nascent AChE in neurons. These unexpected findings open new avenues to modulating AChE activity and its distribution in CNS disorders.
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Pradhan AAA, Becker JAJ, Scherrer G, Tryoen-Toth P, Filliol D, Matifas A, Massotte D, Gavériaux-Ruff C, Kieffer BL. In vivo delta opioid receptor internalization controls behavioral effects of agonists. PLoS One 2009; 4:e5425. [PMID: 19412545 PMCID: PMC2672171 DOI: 10.1371/journal.pone.0005425] [Citation(s) in RCA: 151] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2009] [Accepted: 03/30/2009] [Indexed: 11/19/2022] Open
Abstract
Background GPCRs regulate a remarkable diversity of biological functions, and are thus often targeted for drug therapies. Stimulation of a GPCR by an extracellular ligand triggers receptor signaling via G proteins, and this process is highly regulated. Receptor activation is typically accompanied by desensitization of receptor signaling, a complex feedback regulatory process of which receptor internalization is postulated as a key event. The in vivo significance of GPCR internalization is poorly understood. In fact, the majority of studies have been performed in transfected cell systems, which do not adequately model physiological environments and the complexity of integrated responses observed in the whole animal. Methods and Findings In this study, we used knock-in mice expressing functional fluorescent delta opioid receptors (DOR-eGFP) in place of the native receptor to correlate receptor localization in neurons with behavioral responses. We analyzed the pain-relieving effects of two delta receptor agonists with similar signaling potencies and efficacies, but distinct internalizing properties. An initial treatment with the high (SNC80) or low (AR-M100390) internalizing agonist equally reduced CFA-induced inflammatory pain. However, subsequent drug treatment produced highly distinct responses. Animals initially treated with SNC80 showed no analgesic response to a second dose of either delta receptor agonist. Concomitant receptor internalization and G-protein uncoupling were observed throughout the nervous system. This loss of function was temporary, since full DOR-eGFP receptor responses were restored 24 hours after SNC80 administration. In contrast, treatment with AR-M100390 resulted in retained analgesic response to a subsequent agonist injection, and ex vivo analysis showed that DOR-eGFP receptor remained G protein-coupled on the cell surface. Finally SNC80 but not AR-M100390 produced DOR-eGFP phosphorylation, suggesting that the two agonists produce distinct active receptor conformations in vivo which likely lead to differential receptor trafficking. Conclusions Together our data show that delta agonists retain full analgesic efficacy when receptors remain on the cell surface. In contrast, delta agonist-induced analgesia is abolished following receptor internalization, and complete behavioral desensitization is observed. Overall these results establish that, in the context of pain control, receptor localization fully controls receptor function in vivo. This finding has both fundamental and therapeutic implications for slow-recycling GPCRs.
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MESH Headings
- Animals
- Behavior, Animal/drug effects
- Behavior, Animal/physiology
- Benzamides/pharmacology
- Biological Transport, Active/drug effects
- Cell Membrane/metabolism
- Cells, Cultured
- Green Fluorescent Proteins/chemistry
- Green Fluorescent Proteins/genetics
- Green Fluorescent Proteins/metabolism
- In Vitro Techniques
- Ligands
- Mice
- Mice, Transgenic
- Neurons/drug effects
- Neurons/physiology
- Pain/drug therapy
- Pain/physiopathology
- Phosphorylation
- Piperazines/pharmacology
- Piperidines/pharmacology
- Protein Conformation
- Receptors, Opioid, delta/agonists
- Receptors, Opioid, delta/chemistry
- Receptors, Opioid, delta/genetics
- Receptors, Opioid, delta/physiology
- Recombinant Fusion Proteins/chemistry
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/metabolism
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Affiliation(s)
- Amynah A. A. Pradhan
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique/Institut National de la Santé et de la Recherche Médicale/Université Louis Pasteur, Illkirch, France
| | - Jérôme A. J. Becker
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique/Institut National de la Santé et de la Recherche Médicale/Université Louis Pasteur, Illkirch, France
| | - Grégory Scherrer
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique/Institut National de la Santé et de la Recherche Médicale/Université Louis Pasteur, Illkirch, France
| | - Petra Tryoen-Toth
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique/Institut National de la Santé et de la Recherche Médicale/Université Louis Pasteur, Illkirch, France
| | - Dominique Filliol
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique/Institut National de la Santé et de la Recherche Médicale/Université Louis Pasteur, Illkirch, France
| | - Audrey Matifas
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique/Institut National de la Santé et de la Recherche Médicale/Université Louis Pasteur, Illkirch, France
| | - Dominique Massotte
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique/Institut National de la Santé et de la Recherche Médicale/Université Louis Pasteur, Illkirch, France
| | - Claire Gavériaux-Ruff
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique/Institut National de la Santé et de la Recherche Médicale/Université Louis Pasteur, Illkirch, France
| | - Brigitte L. Kieffer
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique/Institut National de la Santé et de la Recherche Médicale/Université Louis Pasteur, Illkirch, France
- * E-mail:
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Brischoux F, Mainville L, Jones BE. Muscarinic-2 and orexin-2 receptors on GABAergic and other neurons in the rat mesopontine tegmentum and their potential role in sleep-wake state control. J Comp Neurol 2008; 510:607-30. [DOI: 10.1002/cne.21803] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Kieffer BL, Evans CJ. Opioid receptors: from binding sites to visible molecules in vivo. Neuropharmacology 2008; 56 Suppl 1:205-12. [PMID: 18718480 DOI: 10.1016/j.neuropharm.2008.07.033] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2008] [Accepted: 07/24/2008] [Indexed: 12/16/2022]
Abstract
Opioid drugs such as heroin interact directly with opioid receptors whilst other addictive drugs, including marijuana, alcohol and nicotine indirectly activate endogenous opioid systems to contribute to their rewarding properties. The opioid system therefore plays a key role in addiction neurobiology and continues to be a primary focus for NIDA-supported research. Opioid receptors and their peptide ligands, the endorphins and enkephalins, form an extensive heterogeneous network throughout the central and peripheral nervous system. In addition to reward, opioid drugs regulate many functions such that opioid receptors are targets of choice in several physiological, neurological and psychiatric disorders. Because of the multiplicity and diversity of ligands and receptors, opioid receptors have served as an optimal model for G protein coupled receptor (GPCR) research. The isolation of opioid receptor genes opened the way to molecular manipulations of the receptors, both in artificial systems and in vivo, contributing to our current understanding of the diversity of opioid receptor biology at the behavioral, cellular and molecular levels. This review will briefly summarize some aspects of current knowledge that has accumulated since the very early characterization of opioid receptor genes. Importantly, we will identify a number of research directions that are likely to develop during the next decade.
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Affiliation(s)
- Brigitte L Kieffer
- IGBMC (Institut de Génétique et de Biologie Moléculaire et Cellulaire), Département Neurobiologie et génétique, Illkirch, F-67400 France; INSERM, U596, Illkirch F-67400, France; CNRS, UMR7104, Illkirch F-67400, France.
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Zhan L, Liu B, Jose-Lafuente M, Chibalina MV, Grierson A, Maclean A, Nasir J. ALG-2 interacting protein AIP1: a novel link between D1 and D3 signalling. Eur J Neurosci 2008; 27:1626-33. [PMID: 18380665 DOI: 10.1111/j.1460-9568.2008.06135.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Dopamine signalling is a critically important process in the human brain that controls mood, cognition and motor activity. In order to gain detailed insight into this signalling pathway at the molecular level, we carried out yeast two-hybrid screens with D1-like (D1, D5) and D2-like (D2, D3, D4) dopamine receptors and identified 11 dopamine receptor interacting proteins (DRIPs). Using the C-terminal domain of D1 receptor as bait, we identified AIP1 (ALG-2 interacting protein 1), a known modulator of caspase-dependent and caspase-independent cell death, including neuronal cell death, that is also part of the endosomal transport system. In a separate yeast two-hybrid screen, using the third intracellular cytoplasmic loop of D3 as bait, we again identified AIP1. The interaction of AIP1 with both D1 and D3 was confirmed in vitro and in vivo using a variety of methods, including glutathione S-transferase (GST) pull-down, blot overlay and coimmunoprecipitation from mouse brain lysates. We have also observed colocalization of D1 and D3 with AIP1 in mouse brain tissue. In addition, coexpression of AIP1 with D1 resulted in > 50% reduction in binding capacity of D1 to its antagonist. Finally, AIP1 up-regulates D1 and D3 expression and appears to be important for their stability and trafficking.
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Affiliation(s)
- Lingping Zhan
- Academic Neurology Unit, The Henry Wellcome Laboratories for Medical Research, Division of Genomic Medicine, School of Medicine and Biomedical Sciences, University of Sheffield, Beech Hill Road, Sheffield S10 2RX, UK
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Hallett PJ, Collins TL, Standaert DG, Dunah AW. Biochemical fractionation of brain tissue for studies of receptor distribution and trafficking. ACTA ACUST UNITED AC 2008; Chapter 1:Unit 1.16. [PMID: 18428670 DOI: 10.1002/0471142301.ns0116s42] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
An important tool for studying the regulation of synapses is a rapid and reliable means of separating synaptic and intracellular proteins. This unit presents a technique for analysis of brain tissue which relies on differential centrifugation to separate proteins present at synaptic sites from those found in intracellular cytoplasmic and vesicular pools. The method is efficient in that only small amounts of tissue, such as might be obtained from a small region of a rodent brain, are required. It is reproducible and, in conjunction with immunoblot or immunoprecipitation techniques, can produce reliable quantitative data. The protocol will be of interest to those conducting a variety of different studies related to the localization and trafficking of brain receptors and signaling molecules.
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Affiliation(s)
- Penelope J Hallett
- MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts, USA
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35
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Viollet C, Lepousez G, Loudes C, Videau C, Simon A, Epelbaum J. Somatostatinergic systems in brain: networks and functions. Mol Cell Endocrinol 2008; 286:75-87. [PMID: 17997029 DOI: 10.1016/j.mce.2007.09.007] [Citation(s) in RCA: 142] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2007] [Revised: 09/10/2007] [Accepted: 09/19/2007] [Indexed: 12/21/2022]
Abstract
Somatostatin is abundantly expressed in mammalian brain. The peptide binds with high affinity to six somatostatin receptors, sst1, sst2A and B, sst3 to 5, all belonging to the G-protein-coupled receptor family. Recent advances in the neuroanatomy of somatostatin neurons and cellular distribution of sst receptors shed light on their functional roles in the neuronal network. Beside their initially described neuroendocrine role, somatostatin systems subserve neuromodulatory roles in the brain, influencing motor activity, sleep, sensory processes and cognitive functions, and are altered in brain diseases like affective disorders, epilepsia and Alzheimer's disease.
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36
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Subcellular and subsynaptic localization of group I metabotropic glutamate receptors in the nucleus accumbens of cocaine-treated rats. Neuroscience 2008; 154:653-66. [PMID: 18479833 DOI: 10.1016/j.neuroscience.2008.03.049] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2008] [Revised: 03/06/2008] [Accepted: 03/20/2008] [Indexed: 10/22/2022]
Abstract
There is significant pharmacological and behavioral evidence that group I metabotropic glutamate receptors (mGluR1a and mGluR5) in the nucleus accumbens play an important role in the neurochemical and pathophysiological mechanisms that underlie addiction to psychostimulants. To further address this issue, we undertook a detailed ultrastructural analysis to characterize changes in the subcellular and subsynaptic localization of mGluR1a and mGluR5 in the core and shell of nucleus accumbens following acute or chronic cocaine administration in rats. After a single cocaine injection (30 mg/kg) and 45 min withdrawal, there was a significant decrease in the proportion of plasma membrane-bound mGluR1a in accumbens shell dendrites. Similarly, the proportion of plasma membrane-bound mGluR1a was decreased in large dendrites of accumbens core neurons following chronic cocaine exposure (i.e. 1-week treatment followed by 3-week withdrawal). However, neither acute nor chronic cocaine treatments induced significant change in the localization of mGluR5 in accumbens core and shell, which is in contrast with the significant reduction of plasma membrane-bound mGluR1a and mGluR5 induced by local intra-accumbens administration of the group I mGluR agonist, (RS)-3,5-dihydroxyphenylglycine (DHPG). In conclusion, these findings demonstrate that cocaine-induced glutamate imbalance has modest effects on the trafficking of group I mGluRs in the nucleus accumbens. These results provide valuable information on the neuroadaptive mechanisms of accumbens group I mGluRs in response to cocaine administration.
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37
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Porras G, Bezard E. Preclinical development of gene therapy for Parkinson's disease. Exp Neurol 2008; 209:72-81. [PMID: 17904121 DOI: 10.1016/j.expneurol.2007.08.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2007] [Revised: 07/12/2007] [Accepted: 08/07/2007] [Indexed: 12/22/2022]
Abstract
Multiple targets and pathways may be amenable to the development of gene therapy approaches for Parkinson's disease. This article discusses some of the cellular and brain circuit pathways relevant to Parkinson's disease that would be clinically amenable to gene therapy. Approaches could be classified according to two main categories, i.e. symptomatic vs. neuroprotective/neurorestorative strategies. Examples of the different possibilities currently in development are given and feature both dopaminergic and non-dopaminergic symptomatic treatments of parkinsonian symptoms and/or L-DOPA-induced side effects, anti-apoptotic neuroprotective strategies and growth-factor delivery for neuroprotection/neurorestoration. While gene therapy has been mostly used so far for enhancing the expression of the target gene, the use of dominant negative or siRNA opens new possibilities. This, combined with the key feature of gene delivery that offers access to intracellular signalling pathways, is likely to further expand the number of proposed targets to be studied.
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Affiliation(s)
- Grégory Porras
- CNRS UMR 5227, Universite Victor Segalen-Bordeaux 2, 33076, Bordeaux, France
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38
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Willets JM, Nelson CP, Nahorski SR, Challiss RAJ. The regulation of M1 muscarinic acetylcholine receptor desensitization by synaptic activity in cultured hippocampal neurons. J Neurochem 2007; 103:2268-80. [PMID: 17908240 PMCID: PMC2658029 DOI: 10.1111/j.1471-4159.2007.04931.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
To better understand metabotropic/ionotropic integration in neurons we have examined the regulation of M1 muscarinic acetylcholine (mACh) receptor signalling in mature (> 14 days in vitro), synaptically-active hippocampal neurons in culture. Using a protocol where neurons are exposed to an EC(50) concentration of the muscarinic agonist methacholine (MCh) prior to (R1), and following (R2) a desensitizing pulse of a high concentration of this agonist, we have found that the reduction in M(1) mACh receptor responsiveness is decreased in quiescent (+tetrodotoxin) neurons and increased when synaptic activity is enhanced by blocking GABA(A) receptors with picrotoxin. The picrotoxin-mediated effect on M1 mACh receptor responsiveness was completely prevented by alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor blockade. Inhibition of endogenous G protein-coupled receptor kinase 2 by transfection with the non-G(q/11)alpha-binding, catalytically-inactive (D110A,K220R)G protein-coupled receptor kinase 2 mutant, decreased the extent of M1 mACh receptor desensitization under all conditions. Pharmacological inhibition of protein kinase C (PKC) activity, or chronic phorbol ester-induced PKC down-regulation had no effect on agonist-mediated receptor desensitization in quiescent or spontaneously synaptically active neurons, but significantly decreased the extent of receptor desensitization in picrotoxin-treated neurons. MCh stimulated the translocation of diacylglycerol- sensitive eGFP-PKCepsilon, but not Ca2+/diacylglycerol-sensitive eGFP-PKCbetaII in both the absence, and presence of tetrodotoxin. Under these conditions, MCh-stimulated eGFP-myristoylated, alanine-rich C kinase substrate translocation was dependent on PKC activity, but not Ca2+/calmodulin. In contrast, picrotoxin-driven translocation of myristoylated, alanine-rich C kinase substrate was accompanied by translocation of PKCbetaII, but not PKCepsilon, and was dependent on PKC and Ca2+/calmodulin. Taken together these data suggest that the level of synaptic activity may determine the different kinases recruited to regulate M1 mACh receptor desensitization in neurons.
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Affiliation(s)
- Jonathon M Willets
- Department of Cell Physiology and Pharmacology, University of Leicester, Leicester, UK
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Internalization and degradation of the glutamate transporter GLT-1 in response to phorbol ester. Neurochem Int 2007; 52:709-22. [PMID: 17919781 DOI: 10.1016/j.neuint.2007.08.020] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2007] [Revised: 08/09/2007] [Accepted: 08/31/2007] [Indexed: 11/20/2022]
Abstract
Activation of protein kinase C (PKC) decreases the activity and cell surface expression of the predominant forebrain glutamate transporter, GLT-1. In the present study, C6 glioma were used as a model system to define the mechanisms that contribute to this decrease in cell surface expression and to determine the fate of internalized transporter. As was previously observed, phorbol 12-myristate 13-acetate (PMA) caused a decrease in biotinylated GLT-1. This effect was blocked by sucrose or by co-expression with a dominant-negative variant of dynamin 1, and it was attenuated by co-expression with a dominant-negative variant of the clathrin heavy chain. Depletion of cholesterol with methyl-beta-cyclodextrin, co-expression with a dominant-negative caveolin-1 mutant (Cav1/S80E), co-expression with dominant-negative variants of Eps15 (epidermal-growth-factor receptor pathway substrate clone 15), or co-expression with dominant-negative Arf6 (T27N) had no effect on the PMA-induced loss of biotinylated GLT-1. Long-term treatment with PMA caused a time-dependent loss of biotinylated GLT-1 and decreased the levels of GLT-1 protein. Inhibitors of lysosomal degradation (chloroquine or ammonium chloride) or co-expression with a dominant-negative variant of a small GTPase implicated in trafficking to lysosomes (Rab7) prevented the PMA-induced decrease in protein and caused an intracellular accumulation of GLT-1. These results suggest that the PKC-induced redistribution of GLT-1 is dependent upon clathrin-mediated endocytosis. These studies identify a novel mechanism by which the levels of GLT-1 could be rapidly down-regulated via lysosomal degradation. The possibility that this mechanism may contribute to the loss of GLT-1 observed after acute insults to the CNS is discussed.
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Myslivecek J, Duysen EG, Lockridge O. Adaptation to excess acetylcholine by downregulation of adrenoceptors and muscarinic receptors in lungs of acetylcholinesterase knockout mice. Naunyn Schmiedebergs Arch Pharmacol 2007; 376:83-92. [PMID: 17805515 DOI: 10.1007/s00210-007-0184-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2007] [Accepted: 08/06/2007] [Indexed: 10/22/2022]
Abstract
The acetylcholinesterase knockout mouse has elevated acetylcholine levels due to the complete absence of acetylcholinesterase. Our goal was to determine the adaptive changes in lung receptors that allow these animals to tolerate excess neurotransmitter. The hypothesis was tested that not only muscarinic receptors but also alpha(1)-adrenoceptors and beta-adrenoceptors are downregulated, thus maintaining a proper balance of receptors and accounting for lung function in these animals. The quantity of alpha(1A), alpha(1B), alpha(1D), beta(1), and beta(2)-adrenoceptors and muscarinic receptors was determined by binding of radioligands. G-protein coupling was assessed using pseudo-competition with agonists. Phospholipase C activity was measured by an enzymatic assay. Cyclic AMP (cAMP) content was measured by immunoassay. Muscarinic receptors were decreased to 50%, alpha(1)-adrenoceptors to 23%, and beta-adrenoceptors to about 50% of control. Changes were subtype specific, as alpha(1A), alpha(1B), and beta(2)-adrenoceptors, but not alpha(1D)-adrenoceptor, were decreased. In contrast, receptor signaling into the cell as measured by coupling to G proteins, cAMP content, and PI-phospholipase C activity was the same as in control. This shows that the nearly normal lung function of these animals was explained by maintenance of a correct balance of adrenoceptors and muscarinic receptors. In conclusion, knockout mice have adapted to high concentrations of acetylcholine by downregulating receptors that bind acetylcholine, as well as by downregulating receptors that oppose the action of muscarinic receptors. Tolerance to excess acetylcholine is achieved by reducing the levels of muscarinic receptors and adrenoceptors.
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Affiliation(s)
- Jaromir Myslivecek
- Institute of Physiology, 1st Faculty of Medicine, Charles University, Albertov 5, 12800 Prague, Czech Republic.
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Csaba Z, Lelouvier B, Viollet C, El Ghouzzi V, Toyama K, Videau C, Bernard V, Dournaud P. Activated somatostatin type 2 receptors traffic in vivo in central neurons from dendrites to the trans Golgi before recycling. Traffic 2007; 8:820-34. [PMID: 17521381 DOI: 10.1111/j.1600-0854.2007.00580.x] [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: 01/13/2023]
Abstract
Understanding the trafficking of G-protein-coupled receptors (GPCRs) is of particular importance, especially when modifications of the neurochemic environment occur as in pathological or therapeutic circumstances. In the central nervous system, although some GPCRs were reported to internalize in vivo, little is known about their trafficking downstream of the endocytic event. To address this issue, distribution and expression pattern of the major somatostatin receptor subtype, the somatostatin type 2 (sst2), was monitored in the hippocampus using immunofluorescence, autoradiographic and immunogold experiments from 10 minutes to 7 days after in vivo injection of the receptor agonist octreotide. We then analyzed whether postendocytic trafficking of the receptor was dependent upon integrity of the microtubule network using colchicine-injected animals. Together, our results suggest that upon agonist stimulation, dendritic receptors are retrogradely transported through a microtubule-dependent mechanism to a trans Golgi domain enriched in the t-SNARE syntaxin 6 and trans Golgi network 38 proteins, before recycling. Because we show that the exit rate from the trans Golgi apparatus back to the plasma membrane (hours) is slower than the entry rate (minutes), the neuronal postendocytic trafficking of sst2 receptor is likely to have functional consequences in several neurological diseases in which an increase in somatostatin release occurs.
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Affiliation(s)
- Zsolt Csaba
- Neuroendocrine Research Laboratory, Department of Human Morphology and Developmental Biology, Hungarian Academy of Sciences and Semmelweis University, 1094 Budapest, Hungary
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Ehret A, Birthelmer A, Rutz S, Riegert C, Rothmaier AK, Jackisch R. Agonist-mediated regulation of presynaptic receptor function during development of rat septal neurons in culture. J Neurochem 2007; 102:1071-82. [PMID: 17472710 DOI: 10.1111/j.1471-4159.2007.04598.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Presynaptic receptors modulating the release of acetylcholine (ACh) were studied in fetal septal neurons cultured in a growth medium to which various drugs were added from day 3 in vitro (DIV 3) to DIV 14. The influence of these drugs on the function of the presynaptic muscarinic (M-) autoreceptor was determined at DIV 14 by measuring the inhibitory effect of the M-agonist oxotremorine on the electrically-evoked release of [(3)H]ACh from cultures pre-incubated with [(3)H]choline. The presence of the M-agonists oxotremorine (100 micromol/L) or carbachol (100 micromol/L) from DIV 3 to DIV 14, or from DIV 13 to DIV 14, abolished M-autoreceptor function at DIV 14, whereas the presence of the M-antagonist atropine (10 micromol/L from DIV 3 to DIV 14) during growth left M-autoreceptor function unaltered. Inhibition of ACh esterase by donepezil (1 micromol/L from DIV 3 to DIV 14) weakly decreased M-autoreceptor function at DIV 14; inhibition of neuronal firing by 0.1 tetrodotoxin (0.1 micromol/L from DIV 3 to DIV 14) did not tend to affect M-autoreceptor function at DIV 14. Co-cultivation of fetal septal and raphe neurons for 2 weeks yielded cell cultures containing both vesicular ACh transporter- and tryptophan hydroxylase-immunopositive cells. From these cultures, the release of both [(3)H]ACh and [(3)H]5-HT could be induced by electrical field stimulation. In co-cultured neurons versus septal-only ones the inhibitory effect of oxotremorine on the evoked release of [(3)H]ACh appeared almost normal, whereas that of the selective 5-HT(1B) agonist 3-(1,2,5,6-tetrahydropyrid-4-yl)pyrrollo[3,2-b]pyrid-5-one (CP-93,129) was completely abolished. The effects of CP-93,129 were also absent on DIV 14 in septal mono-cultures grown in the presence of CP-93,129 (10 micromol/L) from DIV 3 to DIV 14. It is therefore concluded that the regulation of presynaptic receptor function strongly depends on the concentrations of endogenous transmitters in the neuronal environment.
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Affiliation(s)
- Andreas Ehret
- Laboratory of Neuropharmacology, Institute for Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, Hansastrasse, Freiburg, Germany
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Guigoni C, Doudnikoff E, Li Q, Bloch B, Bezard E. Altered D(1) dopamine receptor trafficking in parkinsonian and dyskinetic non-human primates. Neurobiol Dis 2007; 26:452-63. [PMID: 17350277 DOI: 10.1016/j.nbd.2007.02.001] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2006] [Revised: 01/23/2007] [Accepted: 02/04/2007] [Indexed: 11/24/2022] Open
Abstract
Dyskinesias represent a debilitating complication of levodopa therapy for Parkinson's disease (PD). While we recently demonstrated that levodopa-induced dyskinesia results from increased dopamine D(1) receptor-mediated transmission, we also questioned the possible role of subcellular localization of D(1) and D(2) receptors in mediating these effects as we previously showed that D(1) receptors undergo differential trafficking in striatal neurons of non-dyskinetic PD patients. Taking advantage of a monkey brain bank, we here report changes affecting the cellular and subcellular distribution of D(1) and D(2) dopamine receptors within the striatum of three experimental groups: normal, parkinsonian and dyskinetic L-dopa-treated parkinsonian animals. Our studies at both light and electron microscopy levels show a recruitment of D(1) receptor at the plasma membrane of striatal neurons in the parkinsonian animals and a strong increase of D(1) expression both at the membrane and in cytoplasm of dyskinetic animals, whereas D(2) receptor distribution is only modestly affected in all conditions. Our results rule out the hypothesis of a pathological overinternalization of dopamine receptors in levodopa-induced dyskinesia but raise the possibility for involvement of D(1) receptors in the priming phenomenon through massive and sudden internalization in response to the first ever administration of L-dopa and for an altered homologous desensitization mechanism in dyskinesia leading to an increased availability of D(1) receptors at membrane. Further experiments including parkinsonian monkeys chronically treated with L-dopa that show no dyskinesia and parkinsonian monkeys treated only once with L-dopa are now necessary to confirm our hypothesis.
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Affiliation(s)
- Céline Guigoni
- CNRS UMR 5227, Université Victor Segalen-Bordeaux 2, 146 rue Léo Saignat, 33076 Bordeaux, France
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Stanwood GD, Levitt P. Prenatal exposure to cocaine produces unique developmental and long-term adaptive changes in dopamine D1 receptor activity and subcellular distribution. J Neurosci 2007; 27:152-7. [PMID: 17202482 PMCID: PMC6672298 DOI: 10.1523/jneurosci.4591-06.2007] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Low-dose intravenous cocaine administration to pregnant rabbits causes permanent structural alterations in dopamine-rich cerebral cortical areas, substantially reduced dopamine D1 receptor coupling to G(s)-protein, and deficits in cognitive function. The developmental influences of reduced D1-G(s) coupling and the underlying cellular basis are unknown. Using primary neuronal cultures derived from the medial frontal cortex and striatum of in utero saline- and cocaine-exposed embryos, spontaneous neurite outgrowth of in utero-exposed cortical neurons was greater than in control neurons. In contrast, striatal neurons exposed to cocaine in utero exhibited an entirely opposite adaptive response, with diminished spontaneous neurite outgrowth compared with saline-exposed controls. Control neurons isolated from the two structures also exhibited opposite regulatory responses to the D1 receptor agonist SKF38393 (1-phenyl-2,3,4-5-tetrahydro-(1H)-3-benzazepine-7,8-diol hydrochloride), inhibiting outgrowth in cortical cultures and stimulating outgrowth in striatal cultures. The agonist was ineffective in modulating neurite outgrowth of neurons from either structure isolated from cocaine-exposed fetuses, reflecting the reduced D1-Gs coupling. Total D1 receptor number was indistinguishable in neurons from the cocaine- and saline-exposed animals, but cell imaging and receptor binding of differentially isolated membranes showed that the lack of responsiveness was because of greatly reduced cell-surface localization of D1 receptors. These data suggest that prenatal exposure to cocaine causes a novel, long-lasting adaptive response in the subcellular distribution of D1 receptors, resulting in alterations in signaling capacity that have developmental and behavioral consequences.
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Affiliation(s)
- Gregg D Stanwood
- Vanderbilt Kennedy Center for Research on Human Development and Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA.
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Hannibal J, Georg B, Fahrenkrug J. Melanopsin changes in neonatal albino rat independent of rods and cones. Neuroreport 2007; 18:81-5. [PMID: 17259866 DOI: 10.1097/wnr.0b013e328010ff56] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Intrinsically photosensitive retinal ganglion cells employ the photopigment melanopsin and provide light information to brain areas responsible for the regulation of circadian rhythms. The expression of melanopsin is regulated by environmental illumination, but it remains to be clarified whether the rods and cones are involved. Here, we examined the influence of 5 days of constant light and dark conditions on melanopsin mRNA and protein expression in newborn albino rats, in which functional rods and cones have not yet been developed. We found that the melanopsin mRNA level was unaffected, whereas the melanopsin protein level was more than two-fold higher in the darkness-adapted group than in pups raised in constant light. In pups raised during 12 : 12 h light/dark cycles, the melanopsin protein level was significantly higher during the day than at night. Our findings indicate that melanopsin protein changes are independent of input from the rods and cones.
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Affiliation(s)
- Jens Hannibal
- Department of Clinical Biochemistry, Bispebjerg Hospital, University of Copenhagen, Copenhagen NV, Denmark.
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Ohkuma S, Katsura M, Shibasaki M, Tsujimura A, Hirouchi M. Expression of beta-adrenergic receptor up-regulation is mediated by two different processes. Brain Res 2006; 1112:114-25. [PMID: 16920085 DOI: 10.1016/j.brainres.2006.06.107] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2006] [Revised: 06/29/2006] [Accepted: 06/30/2006] [Indexed: 10/24/2022]
Abstract
Mechanisms of up-regulation of beta-adrenergic receptors (beta-ARs) induced by sustained exposure to 10(-8) M nadolol, a non-selective beta-AR antagonist, were examined using mouse cerebrocortical neurons. Nadolol dose- and time-dependently increased [3H]CGP-12177 bindings to the particulate fractions. This increase occurred 6 h and attained its plateau 12 h after the exposure, whereas beta1- and beta2-AR mRNA significantly increased 24 h and attained their plateaus 3 days after the exposure. Scatchard analysis revealed that the increased bindings were due to increase of receptor density. The [3H]CGP-12177 bindings to beta1- and beta2-ARs increased both 12 h and 5 days after the exposure. Although cycloheximide (CHX) decreased the bindings with or without nadolol, the extent of increase of the bindings induced by nadolol was not affected by CHX. Actinomycin D (AD) with nadolol showed no affects on the bindings 12 h after nadolol exposure, while AD treated 6 h after nadolol exposure significantly reduced the bindings 48 h after nadolol exposure. During 24 h after nadolol exposure, the increase in proteins of beta1- and beta2-ARs in the neuronal membrane was due to the increased receptor protein translocation from cytosol to membrane. These results indicate that the up-regulation of beta-ARs induced by nadolol is mediated by, at least, two different processes, one is increase in translocation of receptor proteins from cytosol to membrane with no changes in synthesis of receptor proteins and their mRNA and another is dependent on receptor protein synthesis with increased synthesis of their mRNA.
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Affiliation(s)
- Seitaro Ohkuma
- Department of Pharmacology, Kawasaki Medical School, Kurashiki 701-0192, Japan.
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