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Joyce JD, Moore GA, Goswami P, Harrell TL, Taylor TM, Hawks SA, Green JC, Jia M, Irwin MD, Leslie E, Duggal NK, Thompson CK, Bertke AS. SARS-CoV-2 Rapidly Infects Peripheral Sensory and Autonomic Neurons, Contributing to Central Nervous System Neuroinvasion before Viremia. Int J Mol Sci 2024; 25:8245. [PMID: 39125815 PMCID: PMC11311394 DOI: 10.3390/ijms25158245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2024] [Revised: 07/17/2024] [Accepted: 07/22/2024] [Indexed: 08/12/2024] Open
Abstract
Neurological symptoms associated with COVID-19, acute and long term, suggest SARS-CoV-2 affects both the peripheral and central nervous systems (PNS/CNS). Although studies have shown olfactory and hematogenous invasion into the CNS, coinciding with neuroinflammation, little attention has been paid to susceptibility of the PNS to infection or to its contribution to CNS invasion. Here we show that sensory and autonomic neurons in the PNS are susceptible to productive infection with SARS-CoV-2 and outline physiological and molecular mechanisms mediating neuroinvasion. Our infection of K18-hACE2 mice, wild-type mice, and golden Syrian hamsters, as well as primary peripheral sensory and autonomic neuronal cultures, show viral RNA, proteins, and infectious virus in PNS neurons, satellite glial cells, and functionally connected CNS tissues. Additionally, we demonstrate, in vitro, that neuropilin-1 facilitates SARS-CoV-2 neuronal entry. SARS-CoV-2 rapidly invades the PNS prior to viremia, establishes a productive infection in peripheral neurons, and results in sensory symptoms often reported by COVID-19 patients.
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Affiliation(s)
- Jonathan D. Joyce
- Translational Biology, Medicine, and Health, Virginia Polytechnic Institute & State University, Blacksburg, VA 24060, USA; (J.D.J.)
- Center for Emerging Zoonotic and Arthropod-borne Pathogens, Virginia Polytechnic Institute & State University, Blacksburg, VA 24060, USA
| | - Greyson A. Moore
- Biomedical and Veterinary Science, Virginia Maryland College of Veterinary Medicine, Virginia Polytechnic Institute & State University, Blacksburg, VA 24060, USA
| | - Poorna Goswami
- Translational Biology, Medicine, and Health, Virginia Polytechnic Institute & State University, Blacksburg, VA 24060, USA; (J.D.J.)
| | - Telvin L. Harrell
- Biomedical and Veterinary Science, Virginia Maryland College of Veterinary Medicine, Virginia Polytechnic Institute & State University, Blacksburg, VA 24060, USA
| | - Tina M. Taylor
- Population Health Sciences, Virginia Maryland College of Veterinary Medicine, Virginia Polytechnic Institute & State University, Blacksburg, VA 24060, USA
| | - Seth A. Hawks
- Biomedical Sciences and Pathobiology, Virginia Polytechnic Institute & State University, Blacksburg, VA 24060, USA
| | - Jillian C. Green
- Biomedical and Veterinary Science, Virginia Maryland College of Veterinary Medicine, Virginia Polytechnic Institute & State University, Blacksburg, VA 24060, USA
| | - Mo Jia
- Population Health Sciences, Virginia Maryland College of Veterinary Medicine, Virginia Polytechnic Institute & State University, Blacksburg, VA 24060, USA
| | - Matthew D. Irwin
- Biomedical and Veterinary Science, Virginia Maryland College of Veterinary Medicine, Virginia Polytechnic Institute & State University, Blacksburg, VA 24060, USA
| | - Emma Leslie
- Translational Biology, Medicine, and Health, Virginia Polytechnic Institute & State University, Blacksburg, VA 24060, USA; (J.D.J.)
| | - Nisha K. Duggal
- Center for Emerging Zoonotic and Arthropod-borne Pathogens, Virginia Polytechnic Institute & State University, Blacksburg, VA 24060, USA
- Biomedical Sciences and Pathobiology, Virginia Polytechnic Institute & State University, Blacksburg, VA 24060, USA
| | - Christopher K. Thompson
- School of Neuroscience, Virginia Polytechnic Institute & State University, Blacksburg, VA 24060, USA
| | - Andrea S. Bertke
- Center for Emerging Zoonotic and Arthropod-borne Pathogens, Virginia Polytechnic Institute & State University, Blacksburg, VA 24060, USA
- Population Health Sciences, Virginia Maryland College of Veterinary Medicine, Virginia Polytechnic Institute & State University, Blacksburg, VA 24060, USA
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2
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Fernández A, Martínez-Ramírez C, Gómez A, de Diego AMG, Gandía L, Casarejos MJ, García AG. Mitochondrial dysfunction in chromaffin cells from the R6/1 mouse model of Huntington's disease: Impact on exocytosis and calcium current regulation. Neurobiol Dis 2023; 179:106046. [PMID: 36806818 DOI: 10.1016/j.nbd.2023.106046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 02/08/2023] [Accepted: 02/15/2023] [Indexed: 02/21/2023] Open
Abstract
From a pathogenic perspective, Huntington's disease (HD) is being considered as a synaptopathy. As such, alterations in brain neurotransmitter release occur. As the activity of the sympathoadrenal axis is centrally controlled, deficits in the exocytotic release of catecholamine release may also occur. In fact, in chromaffin cells (CCs) of the adrenal medulla of the R6/1 model of HD, decrease of secretion and altered kinetics of the exocytotic fusion pore have been reported. Those alterations could be linked to mitochondrial deficits occurring in peripheral CCs, similar to those described in brain mitochondria. Here we have inquired about alterations in mitochondrial structure and function and their impact on exocytosis and calcium channel currents (ICa). We have monitored various parameters linked to those events, in wild type (WT) and the R6/1 mouse model of HD at a pre-disease stage (2 months age, 2 m), and when motor deficits are present (7 months age, 7 m). In isolated CCs from 7 m and in the adrenal medulla of R6/1 mice, we found the following alterations (with respect 7 m WT mice): (i) augmented fragmented mitochondria and oxidative stress with increased oxidized glutathione; (ii) decreased basal and maximal respiration; (iii) diminution of ATP cell levels; (iv) mitochondrial depolarization; (v) drastic decrease of catecholamine release with poorer potentiation by protonophore FCCP; (vi) decreased ICa inhibition by FCCP; and (vii) lesser potentiation by BayK8644 of ICa and smaller prolongation of current deactivation. Of note was the fact several of these alterations were already manifested in CCs from 2 m R6/1 mice at pre-disease stages. Based on those results, a plausible hypothesis can be raised in the sense that altered mitochondrial function seems to be an early primary event in HD pathogenesis. This is in line with an increasing number of mitochondrial, metabolic, and inflammatory alterations being recently reported in various HD peripheral tissues.
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Affiliation(s)
- Ana Fernández
- Instituto Teófilo Hernando, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain; Departamento de Farmacología, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain; Instituto de Investigación Sanitaria del Hospital Universitario de La Princesa, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain; Fundación Teófilo Hernando, Parque científico de Madrid, Cantoblanco, Madrid, Spain
| | - Carmen Martínez-Ramírez
- Instituto Teófilo Hernando, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain; Departamento de Farmacología, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain; Instituto de Investigación Sanitaria del Hospital Universitario de La Princesa, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain; Fundación Teófilo Hernando, Parque científico de Madrid, Cantoblanco, Madrid, Spain
| | - Ana Gómez
- Servicio de Neurobiología, IRYCIS, Hospital Universitario Ramón y Cajal, Madrid, Spain
| | - Antonio M G de Diego
- Instituto Teófilo Hernando, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain; Departamento de Farmacología, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain
| | - Luis Gandía
- Instituto Teófilo Hernando, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain; Departamento de Farmacología, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain; Fundación Teófilo Hernando, Parque científico de Madrid, Cantoblanco, Madrid, Spain
| | - María José Casarejos
- Servicio de Neurobiología, IRYCIS, Hospital Universitario Ramón y Cajal, Madrid, Spain
| | - Antonio G García
- Instituto Teófilo Hernando, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain; Departamento de Farmacología, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain; Instituto de Investigación Sanitaria del Hospital Universitario de La Princesa, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain; Fundación Teófilo Hernando, Parque científico de Madrid, Cantoblanco, Madrid, Spain.
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3
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Deng Y, Wang H, Joni M, Sekhri R, Reiner A. Progression of basal ganglia pathology in heterozygous Q175 knock-in Huntington's disease mice. J Comp Neurol 2021; 529:1327-1371. [PMID: 32869871 PMCID: PMC8049038 DOI: 10.1002/cne.25023] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 08/07/2020] [Accepted: 08/26/2020] [Indexed: 12/29/2022]
Abstract
We used behavioral testing and morphological methods to detail the progression of basal ganglia neuron type-specific pathology and the deficits stemming from them in male heterozygous Q175 mice, compared to age-matched WT males. A rotarod deficit was not present in Q175 mice until 18 months, but increased open field turn rate (reflecting hyperkinesia) and open field anxiety were evident at 6 months. No loss of striatal neurons was seen out to 18 months, but ENK+ and DARPP32+ striatal perikarya were fewer by 6 months, due to diminished expression, with further decline by 18 months. No reduction in SP+ striatal perikarya or striatal interneurons was seen in Q175 mice at 18 months, but cholinergic interneurons showed dendrite attenuation by 6 months. Despite reduced ENK expression in indirect pathway striatal perikarya, ENK-immunostained terminals in globus pallidus externus (GPe) were more abundant at 6 months and remained so out to 18 months. Similarly, SP-immunostained terminals from striatal direct pathway neurons were more abundant in globus pallidus internus and substantia nigra at 6 months and remained so at 18 months. FoxP2+ arkypallidal GPe neurons and subthalamic nucleus neurons were lost by 18 months but not prototypical PARV+ GPe neurons or dopaminergic nigral neurons. Our results show that striatal projection neuron abnormalities and behavioral abnormalities reflecting them develop between 2 and 6 months of age in Q175 male heterozygotes, indicating early effects of the HD mutation. The striatal pathologies resemble those in human HD, but are less severe at 18 months than even in premanifest HD.
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Affiliation(s)
- Yunping Deng
- Department of Anatomy and NeurobiologyThe University of Tennessee Health Science CenterMemphisTennesseeUSA
| | - Hongbing Wang
- Department of Anatomy and NeurobiologyThe University of Tennessee Health Science CenterMemphisTennesseeUSA
| | - Marion Joni
- Department of Anatomy and NeurobiologyThe University of Tennessee Health Science CenterMemphisTennesseeUSA
| | - Radhika Sekhri
- Department of PathologyThe University of Tennessee Health Science CenterMemphisTennesseeUSA
| | - Anton Reiner
- Department of Anatomy and NeurobiologyThe University of Tennessee Health Science CenterMemphisTennesseeUSA
- Department of OphthalmologyThe University of Tennessee Health Science CenterMemphisTennesseeUSA
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4
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The Novel Alpha-2 Adrenoceptor Inhibitor Beditin Reduces Cytotoxicity and Huntingtin Aggregates in Cell Models of Huntington's Disease. Pharmaceuticals (Basel) 2021; 14:ph14030257. [PMID: 33809220 PMCID: PMC7998230 DOI: 10.3390/ph14030257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 03/06/2021] [Accepted: 03/08/2021] [Indexed: 11/17/2022] Open
Abstract
Huntington's disease (HD) is a monogenetic neurodegenerative disorder characterized by the accumulation of polyglutamine-expanded huntingtin (mHTT). There is currently no cure, and therefore disease-slowing remedies are sought to alleviate symptoms of the multifaceted disorder. Encouraging findings in Alzheimer's and Parkinson's disease on alpha-2 adrenoceptor (α2-AR) inhibition have shown neuroprotective and aggregation-reducing effects in cell and animal models. Here, we analyzed the effect of beditin, a novel α2- adrenoceptor (AR) antagonist, on cell viability and mHTT protein levels in cell models of HD using Western blot, time-resolved Foerster resonance energy transfer (TR-FRET), lactate dehydrogenase (LDH) and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) cytotoxicity assays. Beditin decreases cytotoxicity, as measured by TUNEL staining and LDH release, in a neuronal progenitor cell model (STHdh cells) of HD and decreases the aggregation propensity of HTT exon 1 fragments in an overexpression model using human embryonic kidney (HEK) 293T cells. α2-AR is a promising therapeutic target for further characterization in HD models. Our data allow us to suggest beditin as a valuable candidate for the pharmaceutical manipulation of α2-AR, as it is capable of modulating neuronal cell survival and the level of mHTT.
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5
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Blumenstock S, Dudanova I. Cortical and Striatal Circuits in Huntington's Disease. Front Neurosci 2020; 14:82. [PMID: 32116525 PMCID: PMC7025546 DOI: 10.3389/fnins.2020.00082] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 01/21/2020] [Indexed: 12/28/2022] Open
Abstract
Huntington's disease (HD) is a hereditary neurodegenerative disorder that typically manifests in midlife with motor, cognitive, and/or psychiatric symptoms. The disease is caused by a CAG triplet expansion in exon 1 of the huntingtin gene and leads to a severe neurodegeneration in the striatum and cortex. Classical electrophysiological studies in genetic HD mouse models provided important insights into the disbalance of excitatory, inhibitory and neuromodulatory inputs, as well as progressive disconnection between the cortex and striatum. However, the involvement of local cortical and striatal microcircuits still remains largely unexplored. Here we review the progress in understanding HD-related impairments in the cortical and basal ganglia circuits, and outline new opportunities that have opened with the development of modern circuit analysis methods. In particular, in vivo imaging studies in mouse HD models have demonstrated early structural and functional disturbances within the cortical network, and optogenetic manipulations of striatal cell types have started uncovering the causal roles of certain neuronal populations in disease pathogenesis. In addition, the important contribution of astrocytes to HD-related circuit defects has recently been recognized. In parallel, unbiased systems biology studies are providing insights into the possible molecular underpinnings of these functional defects at the level of synaptic signaling and neurotransmitter metabolism. With these approaches, we can now reach a deeper understanding of circuit-based HD mechanisms, which will be crucial for the development of effective and targeted therapeutic strategies.
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Affiliation(s)
- Sonja Blumenstock
- Department of Molecules – Signaling – Development, Max Planck Institute of Neurobiology, Martinsried, Germany
- Molecular Neurodegeneration Group, Max Planck Institute of Neurobiology, Martinsried, Germany
| | - Irina Dudanova
- Molecular Neurodegeneration Group, Max Planck Institute of Neurobiology, Martinsried, Germany
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6
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Ghiglieri V, Campanelli F, Marino G, Natale G, Picconi B, Calabresi P. Corticostriatal synaptic plasticity alterations in the R6/1 transgenic mouse model of Huntington's disease. J Neurosci Res 2019; 97:1655-1664. [PMID: 31498496 DOI: 10.1002/jnr.24521] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 08/13/2019] [Accepted: 08/20/2019] [Indexed: 12/25/2022]
Abstract
Huntington's disease (HD) is a genetic neurodegenerative condition characterized by abnormal dopamine (DA)-glutamate interactions, severe alterations in motor control, and reduced behavioral flexibility. Experimental models of disease show that during symptomatic phases, HD shares with other hyperkinetic disorders the loss of synaptic depotentiation in the striatal spiny projection neurons (SPNs). Here we test the hypothesis that corticostriatal long-term depression (LTD), a well-conserved synaptic scaling down response to environmental stimuli, is also altered in symptomatic male R6/1 mice, a HD model with gradual development of symptoms. In vitro patch-clamp and intracellular recordings of corticostriatal slices from R6/1 mice confirm that, similar to other models characterized by hyperkinesia and striatal DA D1 receptor pathway dysregulation, once long-term potentiation (LTP) is induced, synaptic depotentiation is lost. Our new observations show that activity-dependent LTD was abolished in SPNs of mutant mice. In an experimental condition in which N-methyl-d-aspartate (NMDA) receptors are normally not recruited, in vitro bath application of DA revealed an abnormal response of D1 receptors that caused a shift in synaptic plasticity direction resulting in an NMDA-dependent LTP. Our results demonstrate that corticostriatal LTD is lost in R6/1 mouse model and confirm the role of aberrant DA-glutamate interactions in the alterations of synaptic scaling down associated with HD symptoms.
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Affiliation(s)
- Veronica Ghiglieri
- Dipartimento di Filosofia, Scienze sociali, umane e della formazione, Università di Perugia, Perugia, Italy.,Laboratorio di Neurofisiologia, IRCCS Fondazione Santa Lucia, Rome, Italy
| | | | - Gioia Marino
- Laboratorio di Neurofisiologia, IRCCS Fondazione Santa Lucia, Rome, Italy
| | - Giuseppina Natale
- Laboratorio di Neurofisiologia, IRCCS Fondazione Santa Lucia, Rome, Italy
| | - Barbara Picconi
- Università Telematica San Raffaele, Rome, Italy.,Laboratorio di Neurofisiologia Sperimentale, IRCCS San Raffaele Pisana, Rome, Italy
| | - Paolo Calabresi
- Laboratorio di Neurofisiologia, IRCCS Fondazione Santa Lucia, Rome, Italy.,Clinica Neurologica, Dipartimento di Medicina, Università di Perugia, Perugia, Italy
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7
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Early neurochemical modifications of monoaminergic systems in the R6/1 mouse model of Huntington's disease. Neurochem Int 2019; 128:186-195. [PMID: 31054882 DOI: 10.1016/j.neuint.2019.05.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 04/13/2019] [Accepted: 05/01/2019] [Indexed: 01/10/2023]
Abstract
Huntington's disease (HD) is a rare, autosomal neurodegenerative disease characterized by motor and cognitive impairments appearing in adults. The R6/1 mouse model of the disease recapitulates the adult onset of motor symptoms preceded by cognitive and affective deficits. The monoaminergic systems participate in the establishment of motor and cognitive loops and we postulated that their organization and interaction could be precociously altered. Using tissue measurement of dopamine (DA), serotonin (5-HT), noradrenaline, and some metabolites, we observed that DA and/or its metabolite 3,4-dihydroxyphenylacetic acid (DOPAC), but not 5-HT or noradrenaline tissue content was reduced in an age-dependent manner (from two to six months) in the striatum, substantia nigra and globus pallidus of R6/1 mice. The metabolite of 5-HT was also lower in R6/1 mice, mainly in the substantia nigra and hippocampus. We then addressed early disorganization of monoaminergic systems in 18 brain regions encompassing several neurobiological networks in 35 day-old animals. DA tissue content was not altered in the striatum or substantia nigra but was decreased in the nucleus accumbens and increased in the globus pallidus. The correlations of monoaminergic index in-between the 18 selected brain regions revealed distinct organizations of monoamines in R6/1 mice, notably marked by a loss of the number of correlations of the DOPAC/DA ratio. The neurochemical analyses show that each monoaminergic system is distinctly altered in the R6/1 mouse model. The early abnormal organization of these systems likely points out altered maturation of neurobiological networks at early stages of HD.
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8
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Martínez-Ramírez C, Baraibar AM, Nanclares C, Méndez-López I, Gómez A, Muñoz MP, de Diego AMG, Gandía L, Casarejos MJ, García AG. Altered excitability and exocytosis in chromaffin cells from the R6/1 mouse model of Huntington's disease is linked to over-expression of mutated huntingtin. J Neurochem 2018; 147:454-476. [PMID: 30182387 DOI: 10.1111/jnc.14585] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Revised: 08/07/2018] [Accepted: 08/29/2018] [Indexed: 01/28/2023]
Abstract
As the peripheral sympathoadrenal axis is tightly controlled by the cortex via hypothalamus and brain stem, the central pathological features of Hunting's disease, (HD) that is, deposition of mutated huntingtin and synaptic dysfunctions, could also be expressed in adrenal chromaffin cells. To test this hypothesis we here present a thorough investigation on the pathological and functional changes undergone by chromaffin cells (CCs) from 2-month (2 m) to 7-month (7 m) aged wild-type (WT) and R6/1 mouse model of Huntington's disease (HD), stimulated with acetylcholine (ACh) or high [K+ ] (K+ ). In order to do this, we used different techniques such as inmunohistochemistry, patch-clamp, and amperometric recording. With respect to WT cells, some of the changes next summarized were already observed in HD mice at a pre-disease stage (2 m); however, they were more pronounced at 7 m when motor deficits were clearly established, as follows: (i) huntingtin over-expression as nuclear aggregates in CCs; (ii) smaller CC size with decreased dopamine β-hydroxylase expression, indicating lesser number of chromaffin secretory vesicles; (iii) reduced adrenal tissue catecholamine content; (iv) reduced Na+ currents with (v) membrane hyperpolarization and reduced ACh-evoked action potentials; (v) reduced [Ca2+ ]c transients with faster Ca2+ clearance; (vi) diminished quantal secretion with smaller vesicle quantal size; (vii) faster kinetics of the exocytotic fusion pore, pore expansion, and closure. On the basis of these data, the hypothesis is here raised in the sense that nuclear deposition of mutated huntingtin in adrenal CCs of R6/1 mice could be primarily responsible for poorer Na+ channel expression and function, giving rise to profound depression of cell excitability, altered Ca2+ handling and exocytosis. OPEN PRACTICES: This article has received a badge for *Open Materials* because it provided all relevant information to reproduce the study in the manuscript. The complete Open Science Disclosure form for this article can be found at the end of the article. More information about the Open Practices badges can be found at https://cos.io/our-services/open-science-badges/. Cover Image for this issue: doi: 10.1111/jnc.14201.
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Affiliation(s)
- Carmen Martínez-Ramírez
- Instituto Teófilo Hernando, C/Faraday, Madrid, Spain.,Departamento de Farmacología y Terapéutica, Universidad Autónoma de Madrid, Madrid, Spain.,Instituto de Investigación Sanitaria, Hospital Universitario de La Princesa, Madrid, Spain
| | - Andrés M Baraibar
- Instituto Teófilo Hernando, C/Faraday, Madrid, Spain.,Departamento de Farmacología y Terapéutica, Universidad Autónoma de Madrid, Madrid, Spain
| | - Carmen Nanclares
- Instituto Teófilo Hernando, C/Faraday, Madrid, Spain.,Departamento de Farmacología y Terapéutica, Universidad Autónoma de Madrid, Madrid, Spain
| | - Iago Méndez-López
- Instituto Teófilo Hernando, C/Faraday, Madrid, Spain.,Departamento de Farmacología y Terapéutica, Universidad Autónoma de Madrid, Madrid, Spain.,Instituto de Investigación Sanitaria, Hospital Universitario de La Princesa, Madrid, Spain
| | - Ana Gómez
- Instituto de Investigación Sanitaria, Hospital Universitario Ramón y Cajal, Madrid, Spain
| | - Mᵃ Paz Muñoz
- Instituto de Investigación Sanitaria, Hospital Universitario Ramón y Cajal, Madrid, Spain
| | - Antonio M G de Diego
- Instituto Teófilo Hernando, C/Faraday, Madrid, Spain.,Instituto de Investigación Sanitaria, Hospital Universitario de La Princesa, Madrid, Spain.,DNS Neuroscience, Parque Científico de Madrid, C/Faraday, Madrid, Spain
| | - Luis Gandía
- Instituto Teófilo Hernando, C/Faraday, Madrid, Spain.,Departamento de Farmacología y Terapéutica, Universidad Autónoma de Madrid, Madrid, Spain
| | - María José Casarejos
- Instituto de Investigación Sanitaria, Hospital Universitario Ramón y Cajal, Madrid, Spain
| | - Antonio G García
- Instituto Teófilo Hernando, C/Faraday, Madrid, Spain.,Departamento de Farmacología y Terapéutica, Universidad Autónoma de Madrid, Madrid, Spain.,Instituto de Investigación Sanitaria, Hospital Universitario de La Princesa, Madrid, Spain.,DNS Neuroscience, Parque Científico de Madrid, C/Faraday, Madrid, Spain
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9
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Reiner A, Deng Y. Disrupted striatal neuron inputs and outputs in Huntington's disease. CNS Neurosci Ther 2018; 24:250-280. [PMID: 29582587 PMCID: PMC5875736 DOI: 10.1111/cns.12844] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 02/15/2018] [Accepted: 02/16/2018] [Indexed: 12/22/2022] Open
Abstract
Huntington's disease (HD) is a hereditary progressive neurodegenerative disorder caused by a CAG repeat expansion in the gene coding for the protein huntingtin, resulting in a pathogenic expansion of the polyglutamine tract in the N-terminus of this protein. The HD pathology resulting from the mutation is most prominent in the striatal part of the basal ganglia, and progressive differential dysfunction and loss of striatal projection neurons and interneurons account for the progression of motor deficits seen in this disease. The present review summarizes current understanding regarding the progression in striatal neuron dysfunction and loss, based on studies both in human HD victims and in genetic mouse models of HD. We review evidence on early loss of inputs to striatum from cortex and thalamus, which may be the basis of the mild premanifest bradykinesia in HD, as well as on the subsequent loss of indirect pathway striatal projection neurons and their outputs to the external pallidal segment, which appears to be the basis of the chorea seen in early symptomatic HD. Later loss of direct pathway striatal projection neurons and their output to the internal pallidal segment account for the severe akinesia seen late in HD. Loss of parvalbuminergic striatal interneurons may contribute to the late dystonia and rigidity.
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Affiliation(s)
- Anton Reiner
- Department of Anatomy & NeurobiologyThe University of Tennessee Health Science CenterMemphisTNUSA
- Department of OphthalmologyThe University of Tennessee Health Science CenterMemphisTNUSA
| | - Yun‐Ping Deng
- Department of Anatomy & NeurobiologyThe University of Tennessee Health Science CenterMemphisTNUSA
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10
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Rangel-Barajas C, Rebec GV. Dysregulation of Corticostriatal Connectivity in Huntington's Disease: A Role for Dopamine Modulation. J Huntingtons Dis 2017; 5:303-331. [PMID: 27983564 PMCID: PMC5181679 DOI: 10.3233/jhd-160221] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Aberrant communication between striatum, the main information processing unit of the basal ganglia, and cerebral cortex plays a critical role in the emergence of Huntington’s disease (HD), a fatal monogenetic condition that typically strikes in the prime of life. Although both striatum and cortex undergo substantial cell loss over the course of HD, corticostriatal circuits become dysfunctional long before neurons die. Understanding the dysfunction is key to developing effective strategies for treating a progressively worsening triad of motor, cognitive, and psychiatric symptoms. Cortical output neurons drive striatal activity through the release of glutamate, an excitatory amino acid. Striatal outputs, in turn, release γ-amino butyric acid (GABA) and exert inhibitory control over downstream basal ganglia targets. Ample evidence from transgenic rodent models points to dysregulation of corticostriatal glutamate transmission along with corresponding changes in striatal GABA release as underlying factors in the HD behavioral phenotype. Another contributor is dysregulation of dopamine (DA), a modulator of both glutamate and GABA transmission. In fact, pharmacological manipulation of DA is the only currently available treatment for HD symptoms. Here, we review data from animal models and human patients to evaluate the role of DA in HD, including DA interactions with glutamate and GABA within the context of dysfunctional corticostriatal circuitry.
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Affiliation(s)
| | - George V. Rebec
- Correspondence to: George V. Rebec, PhD, Department of Psychological and Brain Sciences, Program in
Neuroscience, Indiana University, 1101 E. 10th Street, Bloomington, IN 47405-7007, USA. Tel.: +1 812 855 4832;
Fax: +1 812 855 4520; E-mail:
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11
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Cabanas M, Bassil F, Mons N, Garret M, Cho YH. Changes in striatal activity and functional connectivity in a mouse model of Huntington's disease. PLoS One 2017; 12:e0184580. [PMID: 28934250 PMCID: PMC5608247 DOI: 10.1371/journal.pone.0184580] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 08/26/2017] [Indexed: 11/28/2022] Open
Abstract
Hereditary Huntington’s disease (HD) is associated with progressive motor, cognitive and psychiatric symptoms. A primary consequence of the HD mutation is the preferential loss of medium spiny projection cells with relative sparing of local interneurons in the striatum. In addition, among GABAergic striatal projection cells, indirect pathway cells expressing D2 dopamine receptors are lost earlier than direct pathway cells expressing D1 receptors. To test in vivo the functional integrity of direct and indirect pathways as well as interneurons in the striatum of male R6/1 transgenic mice, we assessed their c-Fos expression levels induced by a striatal-dependent cognitive task and compared them with age-matched wild-type littermates. We found a significant increase of c-Fos+ nuclei in the dorsomedial striatum, and this only at 2 months, when our HD mouse model is still pre-motor symptomatic, the increase disappearing with symptom manifestation. Contrary to our expectation, the indirect pathway projection neurons did not undergo any severer changes of c-Fos expression regardless of age in R6/1 mice. We also found a decreased activation of interneurons that express parvalbumin in the dorsomedial striatum at both presymptomatic and symptomatic ages. Finally, analysis of c-Fos expression in extended brain regions involved in the cognitive learning used in our study, demonstrates, throughout ages studied, changes in the functional connectivity between regions in the transgenic mice. Further analysis of the cellular and molecular changes underlying the transient striatal hyperactivity in the HD mice may help to understand the mechanisms involved in the disease onset.
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Affiliation(s)
- Magali Cabanas
- Institut de Neurosciences Cognitives et Intégratives d’Aquitaine, CNRS UMR 5287, Pessac, France
- University of Bordeaux, Bordeaux, France
| | - Fares Bassil
- Institut de Neurosciences Cognitives et Intégratives d’Aquitaine, CNRS UMR 5287, Pessac, France
- University of Bordeaux, Bordeaux, France
| | - Nicole Mons
- Institut de Neurosciences Cognitives et Intégratives d’Aquitaine, CNRS UMR 5287, Pessac, France
- University of Bordeaux, Bordeaux, France
| | - Maurice Garret
- Institut de Neurosciences Cognitives et Intégratives d’Aquitaine, CNRS UMR 5287, Pessac, France
- University of Bordeaux, Bordeaux, France
- * E-mail: (MG); (YHC)
| | - Yoon H. Cho
- Institut de Neurosciences Cognitives et Intégratives d’Aquitaine, CNRS UMR 5287, Pessac, France
- University of Bordeaux, Bordeaux, France
- * E-mail: (MG); (YHC)
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Compromised Dopaminergic Encoding of Reward Accompanying Suppressed Willingness to Overcome High Effort Costs Is a Prominent Prodromal Characteristic of the Q175 Mouse Model of Huntington's Disease. J Neurosci 2017; 36:4993-5002. [PMID: 27147652 DOI: 10.1523/jneurosci.0135-16.2016] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Accepted: 03/15/2016] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED Huntington's disease (HD) is a heritable neurodegenerative disorder caused by expansion of CAG (glutamine) repeats in the HTT gene. A prodromal stage characterized by psychiatric disturbances normally precedes primary motor symptoms and suppressed motivation represents one of the earliest and most common psychiatric symptoms. Although dopamine in the nucleus accumbens (NAc) critically regulates motivation and altered dopamine signaling is implicated in HD, the nature of dopaminergic deficits and contribution to symptoms in HD is poorly understood. We therefore tested whether altered NAc dopamine release accompanies motivational deficits in the Q175 knock-in HD mouse model. Q175 mice express a CAG expansion of the human mutant huntingtin allele in the native mouse genome and gradually manifest symptoms late in life, closely mimicking the genotypic context and disease progression in human HD. Sub-second extracellular dopamine release dynamics were monitored using fast-scan cyclic voltammetry, whereas motivation was assessed using a progressive ratio reinforcement schedule. As the response ratio (lever presses per reward) escalated, Q175 mice exerted less effort to earn fewer rewards versus wild-type (WT). Moreover, dopamine released at reward delivery dynamically encoded increasing reward cost in WT but not Q175 mice. Deficits were specific to situations of high effortful demand as no difference was observed in locomotion, free feeding, hedonic processing, or reward seeking when the response requirement was low. This compromised dopaminergic encoding of reward delivery coincident with suppressed motivation to work for reward in Q175 mice provides novel, neurobiological insight into an established and clinically relevant endophenotype of prodromal HD. SIGNIFICANCE STATEMENT Psychiatric impairments in Huntington's disease (HD) typically manifest early in disease progression, before motor deficits. However, the neurobiological factors contributing to psychiatric symptoms are poorly understood. We used a mouse HD model and assessed whether impaired dopamine release in the nucleus accumbens (NAc), a brain region critical to goal-directed behaviors, accompanies motivational deficits, one of the most common early HD symptoms. HD mice exhibited blunted motivation to work for food reward coincident with diminished dopamine release to reward receipt. Motivational and NAc dopaminergic deficits were not associated with gross motor deficits or impaired food seeking when effortful demands were low. This work identifies a specific prodromal HD phenotype associated with a prominent and previously unidentified neurobiological impairment.
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Tyebji S, Hannan AJ. Synaptopathic mechanisms of neurodegeneration and dementia: Insights from Huntington's disease. Prog Neurobiol 2017; 153:18-45. [PMID: 28377290 DOI: 10.1016/j.pneurobio.2017.03.008] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2016] [Revised: 03/19/2017] [Accepted: 03/30/2017] [Indexed: 12/20/2022]
Abstract
Dementia encapsulates a set of symptoms that include loss of mental abilities such as memory, problem solving or language, and reduces a person's ability to perform daily activities. Alzheimer's disease is the most common form of dementia, however dementia can also occur in other neurological disorders such as Huntington's disease (HD). Many studies have demonstrated that loss of neuronal cell function manifests pre-symptomatically and thus is a relevant therapeutic target to alleviate symptoms. Synaptopathy, the physiological dysfunction of synapses, is now being approached as the target for many neurological and psychiatric disorders, including HD. HD is an autosomal dominant and progressive degenerative disorder, with clinical manifestations that encompass movement, cognition, mood and behaviour. HD is one of the most common tandem repeat disorders and is caused by a trinucleotide (CAG) repeat expansion, encoding an extended polyglutamine tract in the huntingtin protein. Animal models as well as human studies have provided detailed, although not exhaustive, evidence of synaptic dysfunction in HD. In this review, we discuss the neuropathology of HD and how the changes in synaptic signalling in the diseased brain lead to its symptoms, which include dementia. Here, we review and discuss the mechanisms by which the 'molecular orchestras' and their 'synaptic symphonies' are disrupted in neurodegeneration and dementia, focusing on HD as a model disease. We also explore the therapeutic strategies currently in pre-clinical and clinical testing that are targeted towards improving synaptic function in HD.
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Affiliation(s)
- Shiraz Tyebji
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
| | - Anthony J Hannan
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia; Department of Anatomy and Neuroscience, University of Melbourne, Parkville, Victoria, Australia.
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14
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Rothe T, Deliano M, Wójtowicz AM, Dvorzhak A, Harnack D, Paul S, Vagner T, Melnick I, Stark H, Grantyn R. Pathological gamma oscillations, impaired dopamine release, synapse loss and reduced dynamic range of unitary glutamatergic synaptic transmission in the striatum of hypokinetic Q175 Huntington mice. Neuroscience 2015; 311:519-38. [PMID: 26546830 DOI: 10.1016/j.neuroscience.2015.10.039] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Revised: 10/20/2015] [Accepted: 10/21/2015] [Indexed: 11/28/2022]
Abstract
Huntington's disease (HD) is a severe genetically inherited neurodegenerative disorder. Patients present with three principal phenotypes of motor symptoms: choreatic, hypokinetic-rigid and mixed. The Q175 mouse model of disease offers an opportunity to investigate the cellular basis of the hypokinetic-rigid form of HD. At the age of 1 year homozygote Q175 mice exhibited the following signs of hypokinesia: Reduced frequency of spontaneous movements on a precision balance at daytime (-55%), increased total time spent without movement in an open field (+42%), failures in the execution of unconditioned avoidance reactions (+32%), reduced ability for conditioned avoidance (-96%) and increased reaction times (+65%) in a shuttle box. Local field potential recordings revealed low-frequency gamma oscillations in the striatum as a characteristic feature of HD mice at rest. There was no significant loss of DARPP-32 immunolabeled striatal projection neurons (SPNs) although the level of DARPP-32 immunoreactivity was lower in HD. As a potential cause of hypokinesia, HD mice revealed a strong reduction in striatal KCl-induced dopamine release, accompanied by a decrease in the number of tyrosine hydroxylase-(TH)- and VMAT2-positive synaptic varicosities. The presynaptic TH fluorescence level was also reduced. Patch-clamp experiments were performed in slices from 1-year-old mice to record unitary EPSCs (uEPSCs) of presumed cortical origin in the absence of G-protein-mediated modulation. In HD mice, the maximal amplitudes of uEPSCs amounted to 69% of the WT level which matches the loss of VGluT1+/SYP+ synaptic terminals in immunostained sections. These results identify impairment of cortico-striatal synaptic transmission and dopamine release as a potential basis of hypokinesia in HD.
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Affiliation(s)
- T Rothe
- Leibniz Institute for Neurobiology Magdeburg, Germany
| | - M Deliano
- Leibniz Institute for Neurobiology Magdeburg, Germany
| | | | - A Dvorzhak
- Cluster of Excellence NeuroCure, Berlin, Germany
| | - D Harnack
- Department of Experimental Neurology, University Medicine Charité, Berlin, Germany
| | - S Paul
- Cluster of Excellence NeuroCure, Berlin, Germany
| | - T Vagner
- Cluster of Excellence NeuroCure, Berlin, Germany
| | - I Melnick
- Cluster of Excellence NeuroCure, Berlin, Germany; Bogomoletz Institute of Physiology, Kiev, Ukraine
| | - H Stark
- Leibniz Institute for Neurobiology Magdeburg, Germany
| | - R Grantyn
- Cluster of Excellence NeuroCure, Berlin, Germany; Department of Experimental Neurology, University Medicine Charité, Berlin, Germany.
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15
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Neuroanatomical Visualization of the Impaired Striatal Connectivity in Huntington's Disease Mouse Model. Mol Neurobiol 2015; 53:2276-86. [PMID: 25976370 DOI: 10.1007/s12035-015-9214-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2014] [Accepted: 05/06/2015] [Indexed: 10/23/2022]
Abstract
Huntington's disease (HD) is a movement disorder characterized by the early selective degeneration of striatum. For motor control, the striatum receives excitatory inputs from multiple brain regions and projects the information to other basal ganglia nuclei. Despite the pathological importance of the striatal degeneration in HD, there are little anatomical data that show impaired striatal connectivity in HD. For the anatomical mapping of the striatum, we injected here a neurotracer DiD to the dorsal striatum of HD mouse model (YAC128). Compared with littermate controls, the number of the traced inputs to the striatum was reduced dramatically in YAC128 mice at 12 months of age suggesting massive destruction of the striatal connections. Basal ganglia inputs were significantly damaged in HD mice by showing 61 % decrease in substantia nigra pars compacta, 85% decrease in thalamic centromedian nucleus, and 55% decrease in thalamic parafascicular nucleus. Cortical inputs were also greatly decreased by 43% in motor cortex, 48% in somatosensory cortex, and 72% in visual cortex. Besides the known striatal connections, the neurotracer DiD also traced inputs from amygdala and the amygdala inputs were decreased by 68% in YAC128 mice. Considering the role of amygdala in emotion processing, the impairment in amygdalostriatal connectivity strongly suggests that emotional disturbances could occur in HD mice. Indeed, open-field tests further indicated that YAC128 mice exhibited changes in emotional behaviors related to symptoms of depression and anxiety. Although onset of HD is clinically determined on the basis of motor abnormality, emotional deficits are also common features of the disease. Therefore, our anatomical connectivity mapping of the striatum provides a new insight to interpret brain dysfunction in HD.
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Dallérac GM, Levasseur G, Vatsavayai SC, Milnerwood AJ, Cummings DM, Kraev I, Huetz C, Evans KA, Walters SW, Rezaie P, Cho Y, Hirst MC, Murphy KP. Dysfunctional Dopaminergic Neurones in Mouse Models of Huntington's Disease: A Role for SK3 Channels. NEURODEGENER DIS 2015; 15:93-108. [DOI: 10.1159/000375126] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 01/12/2015] [Indexed: 11/19/2022] Open
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Schwab LC, Garas SN, Garas SN, Drouin-Ouellet J, Mason SL, Stott SR, Barker RA. Dopamine and Huntington's disease. Expert Rev Neurother 2015; 15:445-58. [PMID: 25773746 DOI: 10.1586/14737175.2015.1025383] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Huntington's disease (HD) is an incurable, inherited, progressive neurodegenerative disorder that is defined by a combination of motor, cognitive and psychiatric features. Pre-clinical and clinical studies have demonstrated an important role for the dopamine (DA) system in HD with dopaminergic dysfunction at the level of both DA release and DA receptors. It is, therefore, not surprising that the drug treatments most commonly used in HD are anti-dopaminergic agents. Their use is based primarily on the belief that the characteristic motor impairments are a result of overactivation of the central dopaminergic pathways. While this is a useful starting place, it is clear that the behavior of the central dopaminergic pathways is not fully understood in this condition and may change as a function of disease stage. In addition, how abnormalities in dopaminergic systems may underlie some of the non-motor features of HD has also been poorly investigated and this is especially important given the greater burden these place on the patients' and families' quality of life. In this review, we discuss what is known about central dopaminergic pathways in HD and how this informs us about the mechanisms of action of the dopaminergic therapies used to treat it. By doing so, we will highlight some of the paradoxes that exist and how solving them may reveal new insights for improved treatment of this currently incurable condition, including the possibility that such drugs may even have effects on disease progression and pathogenesis.
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Affiliation(s)
- Laetitia C Schwab
- John van Geest Centre for Brain Repair, University of Cambridge, E.D. Adrian Building, Forvie Site, Robinson Way, Cambridge, CB2 0PY, UK
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18
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Renoir T, Argyropoulos A, Chevarin C, Lanfumey L, Hannan AJ. Sexually dimorphic dopaminergic dysfunction in a transgenic mouse model of Huntington's disease. Pharmacol Biochem Behav 2014; 127:15-20. [PMID: 25316307 DOI: 10.1016/j.pbb.2014.10.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Revised: 10/02/2014] [Accepted: 10/06/2014] [Indexed: 02/09/2023]
Abstract
BACKGROUND Using the R6/1 transgenic mouse model of Huntington's disease (HD), we have recently shown that acute administration with the dopamine-norepinephrine reuptake inhibitor bupropion was able to rescue depressive-like behaviours in female HD mice at 12weeks of age. OBJECTIVE In this present study, we aimed to further investigate the dopamine system as well as specifically measure dopamine transporter (DAT) and D1 receptor function in female versus male R6/1 HD mice at a very early stage of the disease. METHODS We assessed the effects of acute administration of bupropion and the dopamine D1 receptor agonist SKF-8129 on spontaneous locomotor activity in 8-week-old HD and wild-type (WT) mice. We also measured dopamine levels in striatum via high performance liquid chromatography (HPLC). RESULTS We found that female (but not male) HD mice were hyposensitive to bupropion when compared to WT littermates. However, both female and male HD mice were less sensitive to SKF-81297 locomotor effects. We also found that striatal dopamine levels and dopamine turnover were reduced in HD animals, regardless of sex. CONCLUSION Our present findings suggest that whereas only female HD mice exhibit an impaired response to bupropion, dopamine D1 receptor function is altered in both female and male HD animals. These data are the first in vivo evidence of impaired dopamine D1 receptor-dependent function in pre-motor symptomatic HD mice suggesting that this is a candidate target for early therapeutic interventions.
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Affiliation(s)
- Thibault Renoir
- Florey Institute of Neuroscience and Mental Health, Melbourne Brain Centre, University of Melbourne, Parkville, Australia.
| | - Andrew Argyropoulos
- Florey Institute of Neuroscience and Mental Health, Melbourne Brain Centre, University of Melbourne, Parkville, Australia; Department of Anatomy and Cell Biology, University of Melbourne, Parkville, Australia
| | - Caroline Chevarin
- Inserm UMR S894, F-75013 Paris, France; UPMC, University of Paris 06, UMR S894, F-75013 Paris, France
| | - Laurence Lanfumey
- Inserm UMR S894, F-75013 Paris, France; UPMC, University of Paris 06, UMR S894, F-75013 Paris, France
| | - Anthony J Hannan
- Florey Institute of Neuroscience and Mental Health, Melbourne Brain Centre, University of Melbourne, Parkville, Australia; Department of Anatomy and Cell Biology, University of Melbourne, Parkville, Australia
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19
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Mo C, Renoir T, Hannan AJ. Novel ethological endophenotypes in a transgenic mouse model of Huntington's disease. Behav Brain Res 2014; 276:17-27. [PMID: 24747660 DOI: 10.1016/j.bbr.2014.04.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Revised: 03/27/2014] [Accepted: 04/01/2014] [Indexed: 12/30/2022]
Abstract
Huntington's disease (HD) is an autosomal dominant, neurodegenerative disorder with a characteristic triad of cognitive, affective and motor symptoms. Transgenic HD mice show excellent construct and face validity for many of these symptoms, however the decline in some facets of every day activity in humans is difficult to model. One approach is the assessment of species-relevant behaviors. Here we described three ethologically appropriate tests in the mouse-olfactory sensitivity, nest-building and sexually-motivated vocalizations. In R6/1 HD mice, olfactory and nest-building tests were sensitive to early dysfunctions induced by the HD mutation. Male vocalization testing revealed a late-stage sexual disinterest in R6/1 HD mice compared to WT littermates. We show that essential, species-relevant functions are disrupted by the HD mutation. The development of integrative behavioral assays which more closely model 'activities of daily living' (ADL) will facilitate the testing of novel therapeutic interventions in animal models as well as their clinical translation.
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Affiliation(s)
- Christina Mo
- Florey Institute of Neuroscience and Mental Health, Kenneth Myer Building, University of Melbourne, Parkville, Melbourne, Australia; Department of Anatomy and Neuroscience, University of Melbourne, Parkville, Melbourne, Australia.
| | - Thibault Renoir
- Florey Institute of Neuroscience and Mental Health, Kenneth Myer Building, University of Melbourne, Parkville, Melbourne, Australia.
| | - Anthony J Hannan
- Florey Institute of Neuroscience and Mental Health, Kenneth Myer Building, University of Melbourne, Parkville, Melbourne, Australia; Department of Anatomy and Neuroscience, University of Melbourne, Parkville, Melbourne, Australia
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20
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Physical exercise-induced adult neurogenesis: a good strategy to prevent cognitive decline in neurodegenerative diseases? BIOMED RESEARCH INTERNATIONAL 2014; 2014:403120. [PMID: 24818140 PMCID: PMC4000963 DOI: 10.1155/2014/403120] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Revised: 02/16/2014] [Accepted: 02/16/2014] [Indexed: 01/19/2023]
Abstract
Cumulative evidence has indicated that there is an important role for adult hippocampal neurogenesis in cognitive function. With the increasing prevalence of cognitive decline associated with neurodegenerative diseases among the ageing population, physical exercise, a potent enhancer of adult hippocampal neurogenesis, has emerged as a potential preventative strategy/treatment to reduce cognitive decline. Here we review the functional role of adult hippocampal neurogenesis in learning and memory, and how this form of structural plasticity is altered in neurodegenerative diseases known to involve cognitive impairment. We further discuss how physical exercise may contribute to cognitive improvement in the ageing brain by preserving adult neurogenesis, and review the recent approaches for measuring changes in neurogenesis in the live human brain.
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Choi ML, Begeti F, Oh JH, Lee SY, O'Keeffe GC, Clelland CD, Tyers P, Cho ZH, Kim YB, Barker RA. Dopaminergic manipulations and its effects on neurogenesis and motor function in a transgenic mouse model of Huntington's disease. Neurobiol Dis 2014; 66:19-27. [PMID: 24561069 DOI: 10.1016/j.nbd.2014.02.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Revised: 01/29/2014] [Accepted: 02/10/2014] [Indexed: 11/28/2022] Open
Abstract
Huntington's disease (HD) is an inherited neurodegenerative disorder that is classically defined by a triad of movement and cognitive and psychiatric abnormalities with a well-established pathology that affects the dopaminergic systems of the brain. This has classically been described in terms of an early loss of dopamine D2 receptors (D2R), although interestingly the treatments most effectively used to treat patients with HD block these same receptors. We therefore sought to examine the dopaminergic system in HD not only in terms of striatal function but also at extrastriatal sites especially the hippocampus, given that transgenic (Tg) mice also exhibit deficits in hippocampal-dependent cognitive tests and a reduction in adult hippocampal neurogenesis. We showed that there was an early reduction of D2R in both the striatum and dentate gyrus (DG) of the hippocampus in the R6/1 transgenic HD mouse ahead of any overt motor signs and before striatal neuronal loss. Despite downregulation of D2Rs in these sites, further reduction of the dopaminergic input to these sites by either medial forebrain bundle lesions or receptor blockade using sulpiride was able to improve both deficits in motor performance and adult hippocampal neurogenesis. In contrast, a reduction in dopaminergic innervation of the neurogenic niches resulted in impaired neurogenesis in healthy WT mice. This study therefore provides evidence that D2R blockade improves hippocampal and striatal deficits in HD mice although the underlying mechanism for this is unclear, and suggests that agents working within this network may have greater effects than previously thought.
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Affiliation(s)
- M L Choi
- Department of Clinical Neurosciences, John van Geest Centre for Brain Repair, University of Cambridge, Cambridge CB2 0PY, UK
| | - F Begeti
- Department of Clinical Neurosciences, John van Geest Centre for Brain Repair, University of Cambridge, Cambridge CB2 0PY, UK; School of Clinical Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge CB2 0SP, UK
| | - J H Oh
- Neuroscience Research Institute, Gachon University, Incheon 405-760, Republic of Korea
| | - S Y Lee
- Neuroscience Research Institute, Gachon University, Incheon 405-760, Republic of Korea
| | - G C O'Keeffe
- Department of Clinical Neurosciences, John van Geest Centre for Brain Repair, University of Cambridge, Cambridge CB2 0PY, UK
| | - C D Clelland
- Department of Clinical Neurosciences, John van Geest Centre for Brain Repair, University of Cambridge, Cambridge CB2 0PY, UK
| | - P Tyers
- Department of Clinical Neurosciences, John van Geest Centre for Brain Repair, University of Cambridge, Cambridge CB2 0PY, UK
| | - Z H Cho
- Department of Clinical Neurosciences, John van Geest Centre for Brain Repair, University of Cambridge, Cambridge CB2 0PY, UK
| | - Y B Kim
- Department of Clinical Neurosciences, John van Geest Centre for Brain Repair, University of Cambridge, Cambridge CB2 0PY, UK
| | - R A Barker
- Department of Clinical Neurosciences, John van Geest Centre for Brain Repair, University of Cambridge, Cambridge CB2 0PY, UK; Department of Neurology, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK.
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22
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Cepeda C, Murphy KPS, Parent M, Levine MS. The role of dopamine in Huntington's disease. PROGRESS IN BRAIN RESEARCH 2014; 211:235-54. [PMID: 24968783 PMCID: PMC4409123 DOI: 10.1016/b978-0-444-63425-2.00010-6] [Citation(s) in RCA: 95] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Alterations in dopamine (DA) neurotransmission in Parkinson's disease are well known and widely studied. Much less is known about DA changes that accompany and underlie some of the symptoms of Huntington's disease (HD), a dominant inherited neurodegenerative disorder characterized by chorea, cognitive deficits, and psychiatric disturbances. The cause is an expansion in CAG (glutamine) repeats in the HTT gene. The principal histopathology of HD is the loss of medium-sized spiny neurons (MSNs) and, to a lesser degree, neuronal loss in cerebral cortex, thalamus, hippocampus, and hypothalamus. Neurochemical, electrophysiological, and behavioral studies in HD patients and genetic mouse models suggest biphasic changes in DA neurotransmission. In the early stages, DA neurotransmission is increased leading to hyperkinetic movements that can be alleviated by depleting DA stores. In contrast, in the late stages, DA deficits produce hypokinesia that can be treated by increasing DA function. Alterations in DA neurotransmission affect glutamate receptor modulation and could contribute to excitotoxicity. The mechanisms of DA dysfunction, in particular the increased DA tone in the early stages of the disease, are presently unknown but may include initial upregulation of DA neuron activity caused by the genetic mutation, reduced inhibition resulting from striatal MSN loss, increased excitation from cortical inputs, and DA autoreceptor dysfunction. Targeting both DA and glutamate receptor dysfunction could be the best strategy to treat HD symptoms.
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Affiliation(s)
- Carlos Cepeda
- Intellectual and Developmental Disabilities Research Center, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Kerry P S Murphy
- Huntington's Disease Research Forum, Department of Life, Health and Chemical Sciences, The Open University, Milton Keynes, Buckinghamshire, UK
| | - Martin Parent
- Department of Psychiatry and Neuroscience, Faculty of Medicine, Université Laval, Centre de Recherche de l'Institut Universitaire en Santé Mentale de Québec, Quebec City, QC, Canada
| | - Michael S Levine
- Intellectual and Developmental Disabilities Research Center, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.
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Ruan L, Lau BWM, Wang J, Huang L, Zhuge Q, Wang B, Jin K, So KF. Neurogenesis in neurological and psychiatric diseases and brain injury: from bench to bedside. Prog Neurobiol 2013; 115:116-37. [PMID: 24384539 DOI: 10.1016/j.pneurobio.2013.12.006] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2013] [Revised: 12/08/2013] [Accepted: 12/12/2013] [Indexed: 02/08/2023]
Abstract
Researchers who have uncovered the presence of stem cells in an adult's central nervous system have not only challenged the dogma that new neurons cannot be generated during adulthood, but also shed light on the etiology and disease mechanisms underlying many neurological and psychiatric disorders. Brain trauma, neurodegenerative diseases, and psychiatric disorders pose enormous burdens at both personal and societal levels. Although medications for these disorders are widely used, the treatment mechanisms underlying the illnesses remain largely elusive. In the past decade, an increasing amount of evidence indicate that adult neurogenesis (i.e. generating new CNS neurons during adulthood) may be involved in the pathology of different CNS disorders, and thus neurogenesis may be a potential target area for treatments. Although new neurons were shown to be a major player in mediating treatment efficacy of neurological and psychotropic drugs on cognitive functions, it is still debatable if the altered production of new neurons can cause the disorders. This review hence seeks to discuss pre and current clinical studies that demonstrate the functional impact adult neurogenesis have on neurological and psychiatric illnesses while examining the related underlying disease mechanisms.
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Affiliation(s)
- Linhui Ruan
- Zhejiang Provincial Key Laboratory of Aging and Neurological Disorder Research, First Affiliated Hospital, Wenzhou Medical University, Wenzhou, China; Department of Pharmacology and Neuroscience, University of North Texas Health Science Center at Fort Worth, TX 76107, USA.
| | - Benson Wui-Man Lau
- Department of Rehabilitation Science, The Hong Kong Polytechnic University, Hong Kong, PR China
| | - Jixian Wang
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center at Fort Worth, TX 76107, USA
| | - Lijie Huang
- Zhejiang Provincial Key Laboratory of Aging and Neurological Disorder Research, First Affiliated Hospital, Wenzhou Medical University, Wenzhou, China; Department of Pharmacology and Neuroscience, University of North Texas Health Science Center at Fort Worth, TX 76107, USA
| | - Qichuan Zhuge
- Zhejiang Provincial Key Laboratory of Aging and Neurological Disorder Research, First Affiliated Hospital, Wenzhou Medical University, Wenzhou, China
| | - Brian Wang
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center at Fort Worth, TX 76107, USA
| | - Kunlin Jin
- Zhejiang Provincial Key Laboratory of Aging and Neurological Disorder Research, First Affiliated Hospital, Wenzhou Medical University, Wenzhou, China; Department of Pharmacology and Neuroscience, University of North Texas Health Science Center at Fort Worth, TX 76107, USA.
| | - Kwok-Fai So
- Department of Ophthalmology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, PR China; The State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Pokfulam, Hong Kong SAR, PR China; Research Centre of Heart, Brain, Hormone and Healthy Aging, Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, PR China; GMH Institute of CNS Regeneration, Jinan University, Guangzhou, PR China.
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Chen JY, Wang EA, Cepeda C, Levine MS. Dopamine imbalance in Huntington's disease: a mechanism for the lack of behavioral flexibility. Front Neurosci 2013; 7:114. [PMID: 23847463 PMCID: PMC3701870 DOI: 10.3389/fnins.2013.00114] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Accepted: 06/13/2013] [Indexed: 01/10/2023] Open
Abstract
Dopamine (DA) plays an essential role in the control of coordinated movements. Alterations in DA balance in the striatum lead to pathological conditions such as Parkinson's and Huntington's diseases (HD). HD is a progressive, invariably fatal neurodegenerative disease caused by a genetic mutation producing an expansion of glutamine repeats and is characterized by abnormal dance-like movements (chorea). The principal pathology is the loss of striatal and cortical projection neurons. Changes in brain DA content and receptor number contribute to abnormal movements and cognitive deficits in HD. In particular, during the early hyperkinetic stage of HD, DA levels are increased whereas expression of DA receptors is reduced. In contrast, in the late akinetic stage, DA levels are significantly decreased and resemble those of a Parkinsonian state. Time-dependent changes in DA transmission parallel biphasic changes in glutamate synaptic transmission and may enhance alterations in glutamate receptor-mediated synaptic activity. In this review, we focus on neuronal electrophysiological mechanisms that may lead to some of the motor and cognitive symptoms of HD and how they relate to dysfunction in DA neurotransmission. Based on clinical and experimental findings, we propose that some of the behavioral alterations in HD, including reduced behavioral flexibility, may be caused by altered DA modulatory function. Thus, restoring DA balance alone or in conjunction with glutamate receptor antagonists could be a viable therapeutic approach.
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Affiliation(s)
- Jane Y Chen
- Intellectual and Developmental Disabilities Research Center, Semel Institute for Neuroscience and Human Behavior and the Brain Research Institute, David Geffen School of Medicine, University of California Los Angeles Los Angeles, CA, USA
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Figiel M, Szlachcic WJ, Switonski PM, Gabka A, Krzyzosiak WJ. Mouse models of polyglutamine diseases: review and data table. Part I. Mol Neurobiol 2012; 46:393-429. [PMID: 22956270 PMCID: PMC3461215 DOI: 10.1007/s12035-012-8315-4] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2012] [Accepted: 07/29/2012] [Indexed: 12/23/2022]
Abstract
Polyglutamine (polyQ) disorders share many similarities, such as a common mutation type in unrelated human causative genes, neurological character, and certain aspects of pathogenesis, including morphological and physiological neuronal alterations. The similarities in pathogenesis have been confirmed by findings that some experimental in vivo therapy approaches are effective in multiple models of polyQ disorders. Additionally, mouse models of polyQ diseases are often highly similar between diseases with respect to behavior and the features of the disease. The common features shared by polyQ mouse models may facilitate the investigation of polyQ disorders and may help researchers explore the mechanisms of these diseases in a broader context. To provide this context and to promote the understanding of polyQ disorders, we have collected and analyzed research data about the characterization and treatment of mouse models of polyQ diseases and organized them into two complementary Excel data tables. The data table that is presented in this review (Part I) covers the behavioral, molecular, cellular, and anatomic characteristics of polyQ mice and contains the most current knowledge about polyQ mouse models. The structure of this data table is designed in such a way that it can be filtered to allow for the immediate retrieval of the data corresponding to a single mouse model or to compare the shared and unique aspects of many polyQ models. The second data table, which is presented in another publication (Part II), covers therapeutic research in mouse models by summarizing all of the therapeutic strategies employed in the treatment of polyQ disorders, phenotypes that are used to examine the effects of the therapy, and therapeutic outcomes.
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Affiliation(s)
- Maciej Figiel
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland.
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Bayram-Weston Z, Jones L, Dunnett SB, Brooks SP. Light and electron microscopic characterization of the evolution of cellular pathology in the R6/1 Huntington's disease transgenic mice. Brain Res Bull 2012; 88:104-12. [DOI: 10.1016/j.brainresbull.2011.07.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Revised: 06/19/2011] [Accepted: 07/12/2011] [Indexed: 12/20/2022]
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Ghiglieri V, Bagetta V, Calabresi P, Picconi B. Functional interactions within striatal microcircuit in animal models of Huntington's disease. Neuroscience 2012; 211:165-84. [DOI: 10.1016/j.neuroscience.2011.06.075] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2011] [Revised: 06/25/2011] [Accepted: 06/28/2011] [Indexed: 11/17/2022]
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Ortiz AN, Osterhaus GL, Lauderdale K, Mahoney L, Fowler SC, von Hörsten S, Riess O, Johnson MA. Motor function and dopamine release measurements in transgenic Huntington's disease model rats. Brain Res 2012; 1450:148-56. [PMID: 22418060 DOI: 10.1016/j.brainres.2012.02.042] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2011] [Revised: 02/01/2012] [Accepted: 02/16/2012] [Indexed: 11/30/2022]
Abstract
Huntington's disease (HD) is a fatal, genetic, neurodegenerative disorder characterized by deficits in motor and cognitive function. Here, we have quantitatively characterized motor deficiencies and dopamine release dynamics in transgenic HD model rats. Behavioral analyses were conducted using a newly-developed force-sensing runway and a previously-developed force-plate actometer. Gait disturbances were readily observed in transgenic HD rats at 12 to 15months of age. Additionally, dopamine system challenge by ip injection of amphetamine also revealed that these rats were resistant to the expression of focused stereotypy compared to wild-type controls. Moreover, dopamine release, evoked by the application of single and multiple electrical stimulus pulses applied at different frequencies, and measured using fast-scan cyclic voltammetry at carbon-fiber microelectrodes, was diminished in transgenic HD rats compared to age-matched wild-type control rats. Collectively, these results underscore the potential contribution of dopamine release alterations to the expression of motor impairments in transgenic HD rats.
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Affiliation(s)
- Andrea N Ortiz
- Department of Chemistry and R. N. Adams Institute for Bioanalytical Chemistry, The University of Kansas, Lawrence, KS 66045, USA
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Rice ME, Patel JC, Cragg SJ. Dopamine release in the basal ganglia. Neuroscience 2011; 198:112-37. [PMID: 21939738 PMCID: PMC3357127 DOI: 10.1016/j.neuroscience.2011.08.066] [Citation(s) in RCA: 193] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Revised: 08/22/2011] [Accepted: 08/26/2011] [Indexed: 10/17/2022]
Abstract
Dopamine (DA) is a key transmitter in the basal ganglia, yet DA transmission does not conform to several aspects of the classic synaptic doctrine. Axonal DA release occurs through vesicular exocytosis and is action potential- and Ca²⁺-dependent. However, in addition to axonal release, DA neurons in midbrain exhibit somatodendritic release by an incompletely understood, but apparently exocytotic, mechanism. Even in striatum, axonal release sites are controversial, with evidence for DA varicosities that lack postsynaptic specialization, and largely extrasynaptic DA receptors and transporters. Moreover, DA release is often assumed to reflect a global response to a population of activities in midbrain DA neurons, whether tonic or phasic, with precise timing and specificity of action governed by other basal ganglia circuits. This view has been reinforced by anatomical evidence showing dense axonal DA arbors throughout striatum, and a lattice network formed by DA axons and glutamatergic input from cortex and thalamus. Nonetheless, localized DA transients are seen in vivo using voltammetric methods with high spatial and temporal resolution. Mechanistic studies using similar methods in vitro have revealed local regulation of DA release by other transmitters and modulators, as well as by proteins known to be disrupted in Parkinson's disease and other movement disorders. Notably, the actions of most other striatal transmitters on DA release also do not conform to the synaptic doctrine, with the absence of direct synaptic contacts for glutamate, GABA, and acetylcholine (ACh) on striatal DA axons. Overall, the findings reviewed here indicate that DA signaling in the basal ganglia is sculpted by cooperation between the timing and pattern of DA input and those of local regulatory factors.
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Affiliation(s)
- M E Rice
- Department of Neurosurgery, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA.
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Effect of enhanced voluntary physical exercise on brain levels of monoamines in Huntington disease mice. PLOS CURRENTS 2011; 3:RRN1281. [PMID: 22266953 PMCID: PMC3208413 DOI: 10.1371/currents.rrn1281] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Accepted: 11/04/2011] [Indexed: 01/15/2023]
Abstract
Using the R6/1 mouse model of Huntington disease (HD), we have recently shown that voluntary physical activity was able to correct the depressive-like behaviours exhibited by the HD animals at a pre-motor symptomatic stage of the disease. Using the high performance liquid chromatography system, we have now evaluated the effect of exercise on monoamine metabolism in HD mice. We found that serotonin and its metabolite as well as dopamine and noradrenaline were reduced across several brain regions in female R6/1 animals. Our data also suggest that some of these neurochemical deficits were modulated by physical activity, in a genotype-region dependent manner. These newly identified changes could account for some of the behavioural effects of exercise previously reported in HD mice.
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Farrar AM, Callahan JW, Abercrombie ED. Reduced striatal acetylcholine efflux in the R6/2 mouse model of Huntington's disease: an examination of the role of altered inhibitory and excitatory mechanisms. Exp Neurol 2011; 232:119-25. [PMID: 21864528 DOI: 10.1016/j.expneurol.2011.08.010] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2011] [Revised: 07/25/2011] [Accepted: 08/08/2011] [Indexed: 10/17/2022]
Abstract
Huntington's disease (HD) is a genetic neurodegenerative disorder that is characterized by the progressive onset of cognitive, psychiatric, and motor symptoms. In parallel, the neuropathology of HD is characterized by progressive loss of projection neurons in cortex and striatum; striatal cholinergic interneurons are relatively spared. Nonetheless, there is evidence that striatal acetylcholine (ACh) function is altered in HD. The present study is the first to examine striatal ACh function in awake, behaving animals, using the R6/2 mouse model of HD, which is transgenic for exon 1 of the mutant huntingtin gene. Physiological levels of extracellular striatal ACh were monitored in R6/2 mice and wild type controls using in vivo microdialysis. Results indicate that spontaneous ACh release is reduced in R6/2 mice relative to controls. Intrastriatal application of the GABA(A) antagonist bicuculline methiodide (10.0 μM) significantly elevated ACh levels in both R6/2 mice and wild type controls, while overall ACh levels were reduced in the R6/2 mice compared to the wild type group. In contrast, systemic administration of the D(1) dopamine receptor partial agonist, SKF-38393 (10.0mg/kg, IP), elevated ACh levels in control animals, but not R6/2 mice. Taken together, the present results suggest that GABA-mediated inhibition of striatal ACh release is intact in R6/2 mice, further demonstrating that cholinergic interneurons are capable of increased ACh release, whereas D(1) receptor-dependent activation of excitatory inputs to striatal cholinergic interneurons is dysfunctional in R6/2 mice. Reduced levels of extracellular striatal ACh in HD may reflect abnormalities in the excitatory innervation of cholinergic interneurons, which may have implications ACh-dependent processes that are altered in HD, including corticostriatal plasticity.
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Affiliation(s)
- Andrew M Farrar
- Center for Molecular and Behavioral Neuroscience, Rutgers, The State University of New Jersey, Newark, NJ 07102, USA.
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Gil-Mohapel J, Simpson JM, Ghilan M, Christie BR. Neurogenesis in Huntington's disease: Can studying adult neurogenesis lead to the development of new therapeutic strategies? Brain Res 2011; 1406:84-105. [DOI: 10.1016/j.brainres.2011.06.040] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2011] [Revised: 06/14/2011] [Accepted: 06/15/2011] [Indexed: 01/01/2023]
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Callahan JW, Abercrombie ED. In vivo Dopamine Efflux is Decreased in Striatum of both Fragment (R6/2) and Full-Length (YAC128) Transgenic Mouse Models of Huntington's Disease. Front Syst Neurosci 2011; 5:61. [PMID: 21811446 PMCID: PMC3139944 DOI: 10.3389/fnsys.2011.00061] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2011] [Accepted: 07/01/2011] [Indexed: 11/28/2022] Open
Abstract
Huntington's disease (HD) is characterized by numerous alterations within the corticostriatal circuitry. The striatum is innervated by a dense array of dopaminergic (DA) terminals and these DA synapses are critical to the proper execution of motor functions. As motor disturbances are prevalent in HD we examined DA neurotransmission in the striatum in transgenic (tg) murine models of HD. We used in vivo microdialysis to compare extracellular concentrations of striatal DA in both a fragment (R6/2) model, which displays a rapid and severe phenotype, and a full-length (YAC128) model that expresses a more progressive phenotype. Extracellular striatal DA concentrations were significantly reduced in R6/2 mice and decreased concomitantly with age-dependent increasing motor impairments on the rotarod task (7, 9, and 11 weeks). In a sample of 11-week-old R6/2 mice, we also measured tissue concentrations of striatal DA and found that total levels of DA were significantly depleted. However, the loss of total DA content (<50%) was insufficient to account for the full extent of DA depletion in the extracellular fluid (ECF; ∼75%). We also observed a significant reduction in extracellular DA concentrations in the striatum of 7-month-old YAC128 mice. In a separate set of experiments, we applied d-amphetamine (AMPH; 10 μm) locally into the striatum to stimulate the release of intracellular DA into the ECF. The AMPH-induced increase in extracellular DA levels was significantly blunted in 9-week-old R6/2 mice. There also was a decrease in AMPH-stimulated DA efflux in 7-month-old YAC128 mice in comparison to WT controls, although the effect was milder. In the same cohort of 7-month-old YAC128 mice we observed a significant reduction in the total locomotor activity in response to systemic AMPH (2 mg/kg). Our data demonstrate that extracellular DA release is attenuated in both a fragment and full-length tg mouse model of HD and support the concept of DA involvement in aspects of the syndrome.
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Affiliation(s)
- Joshua W Callahan
- Center for Molecular and Behavioral Neuroscience, Rutgers, The State University of New Jersey Newark, NJ, USA
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Changes in striatal procedural memory coding correlate with learning deficits in a mouse model of Huntington disease. Proc Natl Acad Sci U S A 2011; 108:9280-5. [PMID: 21576479 DOI: 10.1073/pnas.1016190108] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
In hereditary neurodegenerative Huntington disease (HD), early cognitive impairments before motor deficits have been hypothesized to result from dysfunction in the striatum and cortex before degeneration. To test this hypothesis, we examined the firing properties of single cells and local field activity in the striatum and cortex of pre-motor-symptomatic R6/1 transgenic mice while they were engaged in a procedural learning task, the performance on which typically depends on the integrity of striatum and basal ganglia. Here, we report that a dramatically diminished recruitment of the vulnerable striatal projection cells, but not local interneurons, of R6/1 mice in coding for the task, compared with WT littermates, is associated with severe deficits in procedural learning. In addition, both the striatum and cortex in these mice showed a unique oscillation at high γ-frequency. These data provide crucial information on the in vivo cellular processes in the corticostriatal pathway through which the HD mutation exerts its effects on cognitive abilities in early HD.
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Impaired dopamine release and uptake in R6/1 Huntington's disease model mice. Neurosci Lett 2011; 492:11-4. [PMID: 21256185 DOI: 10.1016/j.neulet.2011.01.036] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Revised: 01/07/2011] [Accepted: 01/13/2011] [Indexed: 11/20/2022]
Abstract
Huntington's disease (HD) is a progressive, neurodegenerative movement disorder. Here, we used fast-scan cyclic voltammetry to measure dopamine release and uptake in striatal brain slices from R6/1 HD model mice. Peak dopamine release ([DA](max)) was significantly diminished in R6/1 mice (52% of wild-type at 24 weeks of age). Similarly, dopamine released per locally applied electrical stimulus pulse ([DA](p)), which is [DA](max) corrected for uptake and electrode performance, was also diminished in R6/1 mice (43% of wild-type by 24 weeks of age). Moreover, V(max), the maximum rate of dopamine uptake, obtained by modeling the stimulated release plots, was decreased at 16 and 24 weeks of age in R6/1 mice (51 and 48% of wild-type, respectively). Thus, impairments in both dopamine release and uptake appear to progress in an age-dependent manner in R6/1 mice.
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Rosenstock TR, Bertoncini CRA, Teles AV, Hirata H, Fernandes MJS, Smaili SS. Glutamate-induced alterations in Ca2+ signaling are modulated by mitochondrial Ca2+ handling capacity in brain slices of R6/1 transgenic mice. Eur J Neurosci 2011; 32:60-70. [PMID: 20608968 DOI: 10.1111/j.1460-9568.2010.07268.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Huntington's disease is a neurodegenerative disorder caused by an expansion of CAGs repeats and characterized by alterations in mitochondrial functions. Although changes in Ca(2+) handling have been suggested, the mechanisms involved are not completely understood. The aim of this study was to investigate the possible alterations in Ca(2+) handling capacity and the relationship with mitochondrial dysfunction evaluated by NAD(P)H fluorescence, reactive oxygen species levels, mitochondrial membrane potential (DeltaPsi(m)) measurements and respiration in whole brain slices from R6/1 mice of different ages, evaluated in situ by real-time real-space microscopy. We show that the cortex and striatum of the 9-month-old R6/1 transgenic mice present a significant sustained increase in cytosolic Ca(2+) induced by glutamate (Glu). This difference in Glu response was partially reduced in R6/1 when in the absence of extracellular Ca(2+), indicating that N-methyl-D-aspartate receptors participation in this response is more important in transgenic mice. In addition, Glu also lead to a decrease in NAD(P)H fluorescence, a loss in DeltaPsi(m) and a further increase in respiration, which may have evoked a decrease in mitochondrial Ca(2+) Ca(2+)(m) uptake capacity. Taken together, these results show that alterations in Ca(2+) homeostasis in transgenic mice are associated with a decrease in Ca(2+)(m) uptake mechanism with a diminished Ca(2+) handling ability that ultimately causes dysfunctions and worsening of the neurodegenerative and the disease processes.
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Affiliation(s)
- T R Rosenstock
- Departamento de Farmacologia, Universidade Federal de São Paulo (UNIFESP/EPM), São Paulo, SP, Brazil
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Experimental Models of HD and Reflection on Therapeutic Strategies. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2011; 98:419-81. [DOI: 10.1016/b978-0-12-381328-2.00016-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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Jahanshahi A, Vlamings R, Kaya AH, Lim LW, Janssen ML, Tan S, Visser-Vandewalle V, Steinbusch HW, Temel Y. Hyperdopaminergic Status in Experimental Huntington Disease. J Neuropathol Exp Neurol 2010; 69:910-7. [DOI: 10.1097/nen.0b013e3181ee005d] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Miller BR, Bezprozvanny I. Corticostriatal circuit dysfunction in Huntington's disease: intersection of glutamate, dopamine and calcium. FUTURE NEUROLOGY 2010; 5:735-756. [PMID: 21977007 DOI: 10.2217/fnl.10.41] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Huntington's disease (HD) is a noncurable and progressive autosomal-dominant neurodegenerative disorder that results from a polyglutamine expansion in the amino-terminal region of the huntingtin protein. The generation of rodent HD models has revealed that cellular dysfunction, rather than cell death alone, occurs early in the disease progression, appearing even before overt symptom onset. Much evidence has now established that dysfunction of the corticostriatal circuit is key to HD symptomology. In this article, we summarize the most current findings that implicate glutamate, dopamine and calcium signaling in this system and discuss how they work in concert to disrupt corticostriatal function. In addition, we highlight therapeutic strategies related to altered corticostriatal signaling in HD.
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Affiliation(s)
- Benjamin Ray Miller
- Department of Physiology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA
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40
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Ebert AD, Barber AE, Heins BM, Svendsen CN. Ex vivo delivery of GDNF maintains motor function and prevents neuronal loss in a transgenic mouse model of Huntington's disease. Exp Neurol 2010; 224:155-62. [PMID: 20227407 DOI: 10.1016/j.expneurol.2010.03.005] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2009] [Revised: 02/17/2010] [Accepted: 03/02/2010] [Indexed: 01/24/2023]
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Wang H, Chen X, Li Y, Tang TS, Bezprozvanny I. Tetrabenazine is neuroprotective in Huntington's disease mice. Mol Neurodegener 2010; 5:18. [PMID: 20420689 PMCID: PMC2873255 DOI: 10.1186/1750-1326-5-18] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2009] [Accepted: 04/26/2010] [Indexed: 11/22/2022] Open
Abstract
Background Huntington's disease (HD) is a neurodegenerative disorder caused by a polyglutamine (polyQ) expansion in Huntingtin protein (Htt). PolyQ expansion in Httexp causes selective degeneration of striatal medium spiny neurons (MSN) in HD patients. A number of previous studies suggested that dopamine signaling plays an important role in HD pathogenesis. A specific inhibitor of vesicular monoamine transporter (VMAT2) tetrabenazine (TBZ) has been recently approved by Food and Drug Administration for treatment of HD patients in the USA. TBZ acts by reducing dopaminergic input to the striatum. Results In previous studies we demonstrated that long-term feeding with TBZ (combined with L-Dopa) alleviated the motor deficits and reduced the striatal neuronal loss in the yeast artificial chromosome transgenic mouse model of HD (YAC128 mice). To further investigate a potential beneficial effects of TBZ for HD treatment, we here repeated TBZ evaluation in YAC128 mice starting TBZ treatment at 2 months of age ("early" TBZ group) and at 6 months of age ("late" TBZ group). In agreement with our previous studies, we found that both "early" and "late" TBZ treatments alleviated motor deficits and reduced striatal cell loss in YAC128 mice. In addition, we have been able to recapitulate and quantify depression-like symptoms in TBZ-treated mice, reminiscent of common side effects observed in HD patients taking TBZ. Conclusions Our results further support therapeutic value of TBZ for treatment of HD but also highlight the need to develop more specific dopamine antagonists which are less prone to side-effects.
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Affiliation(s)
- Hongyu Wang
- Department of Physiology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390, USA.
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Ortiz AN, Kurth BJ, Osterhaus GL, Johnson MA. Dysregulation of intracellular dopamine stores revealed in the R6/2 mouse striatum. J Neurochem 2009; 112:755-61. [PMID: 19929911 DOI: 10.1111/j.1471-4159.2009.06501.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Huntington's disease (HD) is a fatal, neurodegenerative movement disorder characterized by preferential and extensive striatal degeneration. Here, we used fast-scan cyclic voltammetry to study the mobilization and efflux of reserve pool dopamine (DA) in striatal brain slices from HD model R6/2 mice. When applying stimulus trains of 120 pulses, evoked DA release in wild-type (WT) slices was greater than that in R6/2 slices at the higher frequencies (50 and 60 Hz). To quantify cytosolic and reserve pool DA levels, amphetamine-induced DA efflux was measured after pre-treatment with either tetrabenazine or alpha-methyl-p-tyrosine. Slices from 12-week-old R6/2 mice released less DA than slices from WT mice, while no difference was noted in slices from 6-week old mice. The vesicular release of reserve pool DA, mobilized by treatment with cocaine, was shorter lived in R6/2 slices compared with WT slices even though peak DA release was the same. Moreover, the number of DA reserve pool vesicles in R6/2 mice was less than half of that in WT. Therefore, our data suggest that the same number of DA molecules are present in each reserve pool vesicle in WT and R6/2 mice and that these vesicles are readily mobilized in both genotypes; however, R6/2 mice have fewer DA reserve pool vesicles available for mobilization.
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Affiliation(s)
- Andrea N Ortiz
- Department of Chemistry and R. N. Adams Institute for Bioanalytical Chemistry, The University of Kansas, Lawrence, Kansas 66047-7572, USA
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Tinsley RB, Bye CR, Parish CL, Tziotis-Vais A, George S, Culvenor JG, Li QX, Masters CL, Finkelstein DI, Horne MK. Dopamine D2 receptor knockout mice develop features of Parkinson disease. Ann Neurol 2009; 66:472-84. [PMID: 19847912 DOI: 10.1002/ana.21716] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE This study questions whether increased dopamine (DA) turnover in nigral neurons leads to formation of Lewy bodies (LBs), the characteristic alpha-synuclein-containing cytoplasmic inclusion of Parkinson disease (PD). METHODS Mice with targeted deletion of the dopamine D(2) receptor gene (D(2)R[-/-]) have higher striatal and nigral dopamine turnover and elevated oxidative stress. These mice were examined for evidence of histological, biochemical, and gene expression changes consistent with a synucleinopathy. RESULTS LB-like cytoplasmic inclusions containing alpha-synuclein and ubiquitin were present in substantia nigra pars compacta (SNpc) neurons of older D(2)R(-/-) mice, and were also occasionally seen in aged wild-type mice. These inclusions displaced the nucleus of affected cells and were eosinophilic. Diffuse cytosolic alpha-synuclein immunoreactivity in SNpc neurons increased with age in both wild-type and D(2)R(-/-) mice, most likely because of redistribution of alpha-synuclein from striatal terminals to SNpc cell bodies. Gene and protein expression studies indicated endoplasmic reticulum (ER) stress and changes in trafficking and autophagic pathways in D(2)R(-/-) SNpc. These changes were accompanied by a loss of DA terminals in the dorsal striatum, although there was no evidence of progressive cell death in the SNpc. INTERPRETATION Increased sprouting and DA turnover, as observed in PD and D(2)R(-/-) mice, augments LB-like inclusions and axonal degeneration of dopaminergic neurons. These changes are associated with ER stress and autophagy.
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Affiliation(s)
- Rogan B Tinsley
- Howard Florey Institute, the University of Melbourne, Parkville, Australia
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Ferrante RJ. Mouse models of Huntington's disease and methodological considerations for therapeutic trials. BIOCHIMICA ET BIOPHYSICA ACTA 2009; 1792:506-20. [PMID: 19362590 PMCID: PMC2693467 DOI: 10.1016/j.bbadis.2009.04.001] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2009] [Revised: 04/02/2009] [Accepted: 04/02/2009] [Indexed: 12/14/2022]
Abstract
Huntington's disease (HD) is an autosomal dominant, progressive, and fatal neurodegenerative disorder caused by an expanded polyglutamine cytosine-adenine-guanine repeat in the gene coding for the protein huntingtin. Despite great progress, a direct causative pathway from the HD gene mutation to neuronal dysfunction and death has not yet been established. One important advance in understanding the pathogenic mechanisms of this disease has been the development of multiple murine models that replicate many of the clinical, neuropathological, and molecular events in HD patients. These models have played an important role in providing accurate and experimentally accessible systems to study multiple aspects of disease pathogenesis and to test potential therapeutic treatment strategies. Understanding how disease processes interrelate has become important in identifying a pharmacotherapy in HD and in the design of clinical trials. A review of the current state of HD mouse models and their successes in elucidating disease pathogenesis are discussed. There is no clinically proven treatment for HD that can halt or ameliorate the inexorable disease progression. As such, a guide to assessing studies in mouse models and salient issues related to translation from mice to humans are included.
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Affiliation(s)
- Robert J Ferrante
- Geriatric Research Education and Clinical Center, Bedford Veterans Administration Medical Center, Bedford, Massachusetts 01730, USA.
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Kraft JC, Osterhaus GL, Ortiz AN, Garris PA, Johnson MA. In vivo dopamine release and uptake impairments in rats treated with 3-nitropropionic acid. Neuroscience 2009; 161:940-9. [PMID: 19362126 DOI: 10.1016/j.neuroscience.2009.03.083] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2009] [Revised: 03/14/2009] [Accepted: 03/30/2009] [Indexed: 11/17/2022]
Abstract
Recent evidence has suggested that mitochondrial dysfunction may lead to impaired neurotransmitter exocytosis in transgenic Huntington's disease (HD) model mice. To gain insight into the impact of mitochondrial impairment on striatal dopamine release in vivo, we used fast-scan cyclic voltammetry (FSCV) at carbon fiber microelectrodes to measure dopamine release and uptake kinetics in anesthetized Lewis rats continuously treated for 5 days with 3-nitropropionic acid (3NP). Our results indicate that, even though striatal dopamine content was unchanged, remotely stimulated dopamine release evoked per electrical stimulus pulse ([DA](p)) is decreased in 3NP-treated rats (33% of that observed in sham control rats) and that this decrease is uniform throughout all stereotaxic depths tested. Nevertheless, unlike data collected previously from transgenic HD model rodents, the maximum rate of dopamine uptake (V(max)) in 3NP-treated rats is diminished (30% of controls) while K(m) is unchanged. Treatment with 3NP also resulted in a corresponding decrease in locomotor activity, presumably due in part to the impaired dopamine release. These results indicate that dopamine release is degraded in this HD model, as is observed in transgenic HD model rodents; however, the results also imply that there are fundamental differences in dopamine uptake between 3NP-treated animals and transgenic animals.
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Affiliation(s)
- J C Kraft
- Department of Chemistry, The University of Kansas, Lawrence, KS 66045-7582, USA
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Hickey MA, Kosmalska A, Enayati J, Cohen R, Zeitlin S, Levine MS, Chesselet MF. Extensive early motor and non-motor behavioral deficits are followed by striatal neuronal loss in knock-in Huntington's disease mice. Neuroscience 2008; 157:280-95. [PMID: 18805465 DOI: 10.1016/j.neuroscience.2008.08.041] [Citation(s) in RCA: 162] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2008] [Revised: 08/20/2008] [Accepted: 08/21/2008] [Indexed: 01/06/2023]
Abstract
Huntington's disease is a neurodegenerative disorder, caused by an elongation of CAG repeats in the huntingtin gene. Mice with an insertion of an expanded polyglutamine repeat in the mouse huntingtin gene (knock-in mice) most closely model the disease because the mutation is expressed in the proper genomic and protein context. However, few knock-in mouse lines have been extensively characterized and available data suggest marked differences in the extent and time course of their behavioral and pathological phenotype. We have previously described behavioral anomalies in the open field as early as 1 month of age, followed by the appearance at 2 months of progressive huntingtin neuropathology, in a mouse carrying a portion of human exon 1 with approximately 140 CAG repeats inserted into the mouse huntingtin gene. Here we extend these observations by showing that early behavioral anomalies exist in a wide range of motor (climbing, vertical pole, rotarod, and running wheel performance) and non-motor functions (fear conditioning and anxiety) starting at 1-4 months of age, and are followed by progressive gliosis and decrease in dopamine and cyclic AMP-regulated phosphoprotein with molecular weight 32 kDa (DARPP32) (12 months) and a loss of striatal neurons at 2 years. At this age, mice also present striking spontaneous behavioral deficits in their home cage. The data show that this line of knock-in mice reproduces canonical characteristics of Huntington's disease, preceded by deficits which may correspond to the protracted pre-manifest phase of the disease in humans. Accordingly, they provide a useful model to elucidate early mechanisms of pathophysiology and the progression to overt neurodegeneration.
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Affiliation(s)
- M A Hickey
- Department of Neurology, University of California, Los Angeles, David Geffen School of Medicine, Reed Neurological Research Center B114, 710 Westwood Plaza, Los Angeles, CA 90095, USA
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Abstract
Huntington's disease (HD) is an autosomal dominant inherited neurodegenerative disorder in which the neostriatum degenerates early and most severely, with involvement of other brain regions. There is significant evidence that excitotoxicity may play a role in striatal degeneration through altered afferent corticostriatal and nigrostriatal projections that may modulate synaptically released striatal glutamate. Glutamate is a central tenant in provoking excitotoxic cell death in striatal neurons already weakened by the collective molecular events occurring in HD. In addition, transcriptional suppression of trophic factors occurs in human and transgenic mouse models of HD, suggesting that a loss of trophic support might contribute to degeneration. Since anti-glutamate approaches have been effective in improving disease phenotype in HD mice, we examined whether deafferentation of the corticostriatal and nigrostriatal pathways may mitigate striatal stress and neurodegeneration. Both surgical and chemical lesions of the corticostriatal and nigrostriatal pathways, respectively, improved the behavioral, neuropathological, and biochemical phenotype in R6/2 transgenic mice and extended survival. Decortication ameliorated hindlimb clasping, striatal neuron atrophy, and huntingtin-positive aggregates, improved N-acetyl aspartate/creatine levels, reduced oxidative stress, and significantly lowered striatal glutamate levels. In addition, 6-hydroxydopamine lesioned mice showed extended survival along with a significant reduction in striatal glutamate. These results suggest that synaptic stress is likely to contribute to neurodegeneration in HD, whereas transsynaptic trophic influences may not be as salient. Thus, modulation of synaptic influences continues to have therapeutic potential in HD.
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Smith R, Klein P, Koc-Schmitz Y, Waldvogel HJ, Faull RLM, Brundin P, Plomann M, Li JY. Loss of SNAP-25 and rabphilin 3a in sensory-motor cortex in Huntington's disease. J Neurochem 2007; 103:115-23. [PMID: 17877635 DOI: 10.1111/j.1471-4159.2007.04703.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder caused by a CAG-expansion in the gene encoding the protein huntingtin. The disease is characterized by progressive motor disturbances, cognitive defects, dementia, and weight loss. Using western blotting and immunohistochemistry we have assessed the expression levels and patterns of a number of proteins involved in neurotransmitter release in post-mortem frontal cortex samples from 10 HD cases with different disease grades. We report a loss of the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) protein, synaptosome-associated protein 25 (SNAP 25) in HD brains of grades I-IV. Moreover, in brains of grade III and IV we found a reduction in rabphilin 3a, a protein involved in vesicle docking and recycling. These losses appear to be specific and not due to a general loss of synapses in the HD cortex. Thus, levels of synaptobrevin II, syntaxin 1, rab3a or synaptophysin are unaltered in the same patient samples. SNAP 25 and rabphilin 3a are crucial for neurotransmitter release. Therefore, we suggest that a deficient pre-synaptic transmitter release may underlie some of the symptoms of HD.
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Affiliation(s)
- Ruben Smith
- Neuronal Survival Unit, Wallenberg Neuroscience Center, Lund University, Lund, Sweden.
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Johnson MA, Villanueva M, Haynes CL, Seipel AT, Buhler LA, Wightman RM. Catecholamine exocytosis is diminished in R6/2 Huntington's disease model mice. J Neurochem 2007; 103:2102-10. [PMID: 17868298 DOI: 10.1111/j.1471-4159.2007.04908.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
In this work, the mechanisms responsible for dopamine (DA) release impairments observed previously in Huntington's disease model R6/2 mice were evaluated. Voltammetrically measured DA release evoked in striatal brain slices from 12-week old R6/2 mice by a single electrical stimulus pulse was only 19% of wild-type (WT) control mice. Iontophoresis experiments suggest that the concentration of released DA is not diluted by a larger striatal extracellular volume arising from brain atrophy, but, rather, that striatal dopaminergic terminals have a decreased capacity for DA release. This decreased capacity was not due to an altered requirement for extracellular Ca(2+), and, as in WT mice, the release in R6/2 mice required functioning vesicular transporters. Catecholamine secretion from individual vesicles was measured during exocytosis from adrenal chromaffin cells harvested from R6/2 and WT mice. While the number of exocytotic events was unchanged, the amounts released per vesicle were significantly diminished in R6/2 mice, indicating that vesicular catecholamines are present in decreased amounts. Treatment of chromaffin cells with 3-nitropropionic acid decreased the vesicular release amount from WT cells by 50%, mimicking the release observed from untreated R6/2 cells. Thus, catecholamine release from tissues isolated from R6/2 mice is diminished because of impaired vesicle loading.
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Affiliation(s)
- Michael A Johnson
- Department of Chemistry The University of North Carolina, Chapel Hill, North Carolina, USA
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Tang TS, Chen X, Liu J, Bezprozvanny I. Dopaminergic signaling and striatal neurodegeneration in Huntington's disease. J Neurosci 2007; 27:7899-910. [PMID: 17652581 PMCID: PMC3307545 DOI: 10.1523/jneurosci.1396-07.2007] [Citation(s) in RCA: 167] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Huntington's disease (HD) is a neurodegenerative disorder caused by polyglutamine (polyQ) expansion in Huntingtin protein (Htt). PolyQ expansion in Htt(exp) causes selective degeneration of striatal medium spiny neurons (MSNs) in HD patients. Striatal MSN neurons receive glutamatergic input from the cortex and dopaminergic input from the substantia nigra. In previous studies with the yeast artificial chromosome (YAC128) transgenic HD mouse model, we established a connection between glutamate receptor activation, disturbed calcium (Ca2+) signaling, and apoptosis of HD MSNs (Tang et al., 2005). Here, we used the same YAC128 mouse model to investigate the role of dopaminergic signaling in HD. We discovered that glutamate and dopamine signaling pathways act synergistically to induce elevated Ca2+ signals and to cause apoptosis of YAC128 MSNs in vitro. We demonstrated that potentiating effects of dopamine are mediated by D1-class dopamine receptors (DARs) and not by D2-class DARs. Consistent with in vitro findings, in whole-animal experiments we found that persistent elevation of striatal dopamine levels exacerbated the behavioral motor deficits and MSN neurodegeneration in YAC128 mice. We further discovered that the clinically relevant dopamine pathway inhibitor tetrabenazine alleviated the motor deficits and reduced striatal cell loss in YAC128 mice. Our results suggest that dopamine signaling pathway plays an important role in HD pathogenesis and that antagonists of dopamine pathway such as tetrabenazine or dopamine receptor blockers may have a therapeutic potential for treatment of HD beyond well established "symptomatic" benefit.
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Affiliation(s)
- Tie-Shan Tang
- Department of Physiology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
| | - Xi Chen
- Department of Physiology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
| | - Jing Liu
- Department of Physiology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
| | - Ilya Bezprozvanny
- Department of Physiology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
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