1
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Jellinger KA. Pathomechanisms of behavioral abnormalities in Huntington disease: an update. J Neural Transm (Vienna) 2024:10.1007/s00702-024-02794-y. [PMID: 38874766 DOI: 10.1007/s00702-024-02794-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2024] [Accepted: 06/05/2024] [Indexed: 06/15/2024]
Abstract
Huntington disease (HD), a devastating autosomal-dominant neurodegenerative disease caused by an expanded CAG trinucleotide repeat, is clinically characterized by a triad of symptoms including involuntary motions, behavior problems and cognitive deficits. Behavioral symptoms with anxiety, irritability, obsessive-compulsive behaviors, apathy and other neuropsychiatric symptoms, occurring in over 50% of HD patients are important features of this disease and contribute to impairment of quality of life, but their pathophysiology is poorly understood. Behavior problems, more frequent than depression, can be manifest before obvious motor symptoms and occur across all HD stages, usually correlated with duration of illness. While specific neuropathological data are missing, the relations between gene expression and behavior have been elucidated in transgenic models of HD. Disruption of interneuronal communications, with involvement of prefronto-striato-thalamic networks and hippocampal dysfunctions produce deficits in multiple behavioral domains. These changes that have been confirmed by multistructural neuroimaging studies are due to a causal cascade linking molecular pathologies (glutamate-mediated excitotoxicity, mitochondrial dysfunctions inducing multiple biochemical and structural alterations) and deficits in multiple behavioral domains. The disruption of large-scale connectivities may explain the variability of behavior profiles and is useful in understanding the biological backgrounds of functional decline in HD. Such findings offer new avenues for targeted treatments in terms of minimizing neurobehavioral impairment in HD.
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Affiliation(s)
- Kurt A Jellinger
- Institute of Clinical Neurobiology, Alberichgasse 5/13, Vienna, A-1150, Austria.
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2
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Wang Y, Ramandi D, Sepers MD, Mackay JP, Raymond LA. Age- and region-dependent cortical excitability in the zQ175 Huntington disease mouse model. Hum Mol Genet 2024; 33:387-399. [PMID: 37947186 PMCID: PMC10877458 DOI: 10.1093/hmg/ddad191] [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: 07/17/2023] [Revised: 09/29/2023] [Accepted: 11/02/2023] [Indexed: 11/12/2023] Open
Abstract
The neurodegenerative disorder, Huntington disease (HD), manifests as disorders of movement, cognition and mood. Although studies report abnormal corticostriatal synaptic function early in HD mouse models, less is known about cortical-cortical activity across brain regions and disease stages. Recently, we reported enhanced mesoscale spread of cortical responses to sensory stimulation in vivo at early-manifest stages of two HD mouse models. Here, we investigated cortical excitability of zQ175 HD-model mice compared to their wild-type littermates across different cell types, ages and/or cortical regions using ex vivo electrophysiology. Cortical pyramidal neurons (CPNs) in somatosensory cortex of zQ175 mice showed intrinsic hyper-excitability at 3-4 months, but hypo-excitability at early-manifest stage (8-9 months); reduced frequency of spontaneous excitatory postsynaptic currents (sEPSCs) was seen at both ages. In contrast, motor cortex CPNs in early-manifest zQ175 mice showed increased intrinsic excitability and sEPSC frequency. Large-amplitude excitatory discharges recorded from CPNs in early-manifest zQ175 mice showed increased frequency only in somatosensory cortex, suggesting the intrinsic hypo-excitability of these CPNs may be compensatory against cortical network hyper-excitability. Similarly, in early-manifest zQ175 mice, region-dependent differences were seen in fast-spiking interneurons (FSIs): somatosensory but not motor FSIs from early-manifest zQ175 mice had reduced intrinsic excitability. Moreover, CPNs showed decreased frequency of spontaneous inhibitory postsynaptic currents and increased excitatory-inhibitory (E-I) balance of evoked synaptic currents in somatosensory cortex. Aberrant large-amplitude discharges and reduced inhibitory drive may therefore underlie E-I imbalances that result in circuit changes and synaptic dysfunction in early-manifest HD.
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Affiliation(s)
- Yundi Wang
- Department of Psychiatry and Djavad Mowafaghian Centre for Brain Health, 2215 Wesbrook Mall, Vancouver, V6T 1Z3, Canada
| | - Daniel Ramandi
- Department of Psychiatry and Djavad Mowafaghian Centre for Brain Health, 2215 Wesbrook Mall, Vancouver, V6T 1Z3, Canada
- Graduate Program in Cell and Developmental Biology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, V6T 2A1, Canada
| | - Marja D Sepers
- Department of Psychiatry and Djavad Mowafaghian Centre for Brain Health, 2215 Wesbrook Mall, Vancouver, V6T 1Z3, Canada
| | - James P Mackay
- Department of Psychiatry and Djavad Mowafaghian Centre for Brain Health, 2215 Wesbrook Mall, Vancouver, V6T 1Z3, Canada
| | - Lynn A Raymond
- Department of Psychiatry and Djavad Mowafaghian Centre for Brain Health, 2215 Wesbrook Mall, Vancouver, V6T 1Z3, Canada
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3
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Nassrallah WB, Ramandi D, Cheng J, Oh J, Mackay J, Sepers MD, Lau D, Bading H, Raymond LA. Activin A targets extrasynaptic NMDA receptors to ameliorate neuronal and behavioral deficits in a mouse model of Huntington disease. Neurobiol Dis 2023; 189:106360. [PMID: 37992785 DOI: 10.1016/j.nbd.2023.106360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 11/08/2023] [Accepted: 11/18/2023] [Indexed: 11/24/2023] Open
Abstract
Cortical-striatal synaptic dysfunction, including enhanced toxic signaling by extrasynaptic N-methyl-d-aspartate receptors (eNMDARs), precedes neurodegeneration in Huntington disease (HD). A previous study showed Activin A, whose transcription is upregulated by calcium influx via synaptic NMDARs, suppresses eNMDAR signaling. Therefore, we examined the role of Activin A in the YAC128 HD mouse model, comparing it to wild-type controls. We found decreased Activin A secretion in YAC128 cortical-striatal co-cultures, while Activin A overexpression in this model rescued altered eNMDAR expression. Striatal overexpression of Activin A in vivo improved motor learning on the rotarod task, and normalized striatal neuronal eNMDAR-mediated currents, membrane capacitance and spontaneous excitatory postsynaptic current frequency in the YAC128 mice. These results support the therapeutic potential of Activin A signaling and targeting eNMDARs to restore striatal neuronal health and ameliorate behavioral deficits in HD.
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Affiliation(s)
- Wissam B Nassrallah
- Graduate Program in Neuroscience, University of British Columbia, Canada; University of British Columbia, Vancouver, BC, Canada; Department of Psychiatry, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Canada
| | - Daniel Ramandi
- Graduate Program in Cell and Developmental Biology, University of British Columbia, Canada; Department of Psychiatry, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Canada
| | - Judy Cheng
- Graduate Program in Neuroscience, University of British Columbia, Canada; Department of Psychiatry, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Canada
| | - Jean Oh
- Department of Psychiatry, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Canada
| | - James Mackay
- Department of Psychiatry, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Canada
| | - Marja D Sepers
- Department of Psychiatry, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Canada
| | - David Lau
- Department of Neurobiology, Interdisciplinary Center for Neurosciences (IZN), Heidelberg University, Heidelberg, Germany
| | - Hilmar Bading
- Department of Neurobiology, Interdisciplinary Center for Neurosciences (IZN), Heidelberg University, Heidelberg, Germany
| | - Lynn A Raymond
- Department of Psychiatry, Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Canada; Department of Medicine, Division of Neurology, University of British Columbia, Canada.
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4
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Wilton DK, Mastro K, Heller MD, Gergits FW, Willing CR, Fahey JB, Frouin A, Daggett A, Gu X, Kim YA, Faull RLM, Jayadev S, Yednock T, Yang XW, Stevens B. Microglia and complement mediate early corticostriatal synapse loss and cognitive dysfunction in Huntington's disease. Nat Med 2023; 29:2866-2884. [PMID: 37814059 PMCID: PMC10667107 DOI: 10.1038/s41591-023-02566-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 08/24/2023] [Indexed: 10/11/2023]
Abstract
Huntington's disease (HD) is a devastating monogenic neurodegenerative disease characterized by early, selective pathology in the basal ganglia despite the ubiquitous expression of mutant huntingtin. The molecular mechanisms underlying this region-specific neuronal degeneration and how these relate to the development of early cognitive phenotypes are poorly understood. Here we show that there is selective loss of synaptic connections between the cortex and striatum in postmortem tissue from patients with HD that is associated with the increased activation and localization of complement proteins, innate immune molecules, to these synaptic elements. We also found that levels of these secreted innate immune molecules are elevated in the cerebrospinal fluid of premanifest HD patients and correlate with established measures of disease burden.In preclinical genetic models of HD, we show that complement proteins mediate the selective elimination of corticostriatal synapses at an early stage in disease pathogenesis, marking them for removal by microglia, the brain's resident macrophage population. This process requires mutant huntingtin to be expressed in both cortical and striatal neurons. Inhibition of this complement-dependent elimination mechanism through administration of a therapeutically relevant C1q function-blocking antibody or genetic ablation of a complement receptor on microglia prevented synapse loss, increased excitatory input to the striatum and rescued the early development of visual discrimination learning and cognitive flexibility deficits in these models. Together, our findings implicate microglia and the complement cascade in the selective, early degeneration of corticostriatal synapses and the development of cognitive deficits in presymptomatic HD; they also provide new preclinical data to support complement as a therapeutic target for early intervention.
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Affiliation(s)
- Daniel K Wilton
- F. M. Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, US.
| | - Kevin Mastro
- F. M. Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, US
| | - Molly D Heller
- F. M. Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, US
| | - Frederick W Gergits
- F. M. Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, US
| | - Carly Rose Willing
- F. M. Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, US
| | - Jaclyn B Fahey
- F. M. Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, US
| | - Arnaud Frouin
- F. M. Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, US
| | - Anthony Daggett
- Center for Neurobehavioral Genetics, Jane and Terry Semel Institute for Neuroscience and Human Behavior, Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine at University of California, Los Angeles, CA, USA
| | - Xiaofeng Gu
- Center for Neurobehavioral Genetics, Jane and Terry Semel Institute for Neuroscience and Human Behavior, Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine at University of California, Los Angeles, CA, USA
| | - Yejin A Kim
- F. M. Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, US
| | - Richard L M Faull
- Department of Anatomy with Radiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Suman Jayadev
- Department of Neurology, University of Washington, Seattle, WA, USA
- Division of Medical Genetics, Department of Medicine, University of Washington, Seattle, WA, USA
| | - Ted Yednock
- Annexon Biosciences, South San Francisco, CA, USA
| | - X William Yang
- Center for Neurobehavioral Genetics, Jane and Terry Semel Institute for Neuroscience and Human Behavior, Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine at University of California, Los Angeles, CA, USA
| | - Beth Stevens
- F. M. Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, US.
- Stanley Center, Broad Institute, Cambridge, MA, USA.
- Howard Hughes Medical Institute, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.
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5
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Estrada-Sánchez AM, Rangel-Barajas C, Howe AG, Barton SJ, Mach RH, Luedtke RR, Rebec GV. Selective Activation of D3 Dopamine Receptors Ameliorates DOI-Induced Head Twitching Accompanied by Changes in Corticostriatal Processing. Int J Mol Sci 2023; 24:ijms24119300. [PMID: 37298250 DOI: 10.3390/ijms24119300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 05/19/2023] [Accepted: 05/23/2023] [Indexed: 06/12/2023] Open
Abstract
D3 receptors, a key component of the dopamine system, have emerged as a potential target of therapies to improve motor symptoms across neurodegenerative and neuropsychiatric conditions. In the present work, we evaluated the effect of D3 receptor activation on the involuntary head twitches induced by 2,5-dimethoxy-4-iodoamphetamine (DOI) at behavioral and electrophysiological levels. Mice received an intraperitoneal injection of either a full D3 agonist, WC 44 [4-(2-fluoroethyl)-N-[4-[4-(2-methoxyphenyl)piperazin 1-yl]butyl]benzamide] or a partial D3 agonist, WW-III-55 [N-(4-(4-(4-methoxyphenyl)piperazin-1-yl)butyl)-4-(thiophen-3-yl)benzamide] five minutes before the intraperitoneal administration of DOI. Compared to the control group, both D3 agonists delayed the onset of the DOI-induced head-twitch response and reduced the total number and frequency of the head twitches. Moreover, the simultaneous recording of neuronal activity in the motor cortex (M1) and dorsal striatum (DS) indicated that D3 activation led to slight changes in a single unit activity, mainly in DS, and increased its correlated firing in DS or between presumed cortical pyramidal neurons (CPNs) and striatal medium spiny neurons (MSNs). Our results confirm the role of D3 receptor activation in controlling DOI-induced involuntary movements and suggest that this effect involves, at least in part, an increase in correlated corticostriatal activity. A further understanding of the underlying mechanisms may provide a suitable target for treating neuropathologies in which involuntary movements occur.
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Affiliation(s)
- Ana María Estrada-Sánchez
- Program in Neuroscience and Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405, USA
- División de Biología Molecular, Instituto Potosino de Investigación Científica y Tecnológica (IPICYT), Camino a la Presa San José No. 2055, Colonia Lomas 4a Sección, San Luis Potosi C.P. 78216, Mexico
| | - Claudia Rangel-Barajas
- Program in Neuroscience and Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405, USA
| | - Andrew G Howe
- Psychology Department, University of California Los Angeles, Los Angeles, CA 90095, USA
- Intelligent Systems Laboratory, HRL Laboratories, LLC., Malibu, CA 90265, USA
| | - Scott J Barton
- Program in Neuroscience and Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405, USA
| | - Robert H Mach
- Department of Radiology, University of Pennsylvania School of Medicine, Chemistry Building, 231 S. 34th St., Philadelphia, PA 19104, USA
| | - Robert R Luedtke
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, 3500 Camp Bowie Boulevard, Fort Worth, TX 76107, USA
| | - George V Rebec
- Program in Neuroscience and Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405, USA
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6
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Vasilkovska T, Adhikari M, Van Audekerke J, Salajeghe S, Pustina D, Cachope R, Tang H, Liu L, Munoz-Sanjuan I, Van der Linden A, Verhoye M. Resting-state fMRI reveals longitudinal alterations in brain network connectivity in the zQ175DN mouse model of Huntington's disease. Neurobiol Dis 2023; 181:106095. [PMID: 36963694 DOI: 10.1016/j.nbd.2023.106095] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2023] [Revised: 03/13/2023] [Accepted: 03/20/2023] [Indexed: 03/26/2023] Open
Abstract
Huntington's disease is an autosomal, dominantly inherited neurodegenerative disease caused by an expansion of the CAG repeats in exon 1 of the huntingtin gene. Neuronal degeneration and dysfunction that precedes regional atrophy result in the impairment of striatal and cortical circuits that affect the brain's large-scale network functionality. However, the evolution of these disease-driven, large-scale connectivity alterations is still poorly understood. Here we used resting-state fMRI to investigate functional connectivity changes in a mouse model of Huntington's disease in several relevant brain networks and how they are affected at different ages that follow a disease-like phenotypic progression. Towards this, we used the heterozygous (HET) form of the zQ175DN Huntington's disease mouse model that recapitulates aspects of human disease pathology. Seed- and Region-based analyses were performed at different ages, on 3-, 6-, 10-, and 12-month-old HET and age-matched wild-type mice. Our results demonstrate decreased connectivity starting at 6 months of age, most prominently in regions such as the retrosplenial and cingulate cortices, pertaining to the default mode-like network and auditory and visual cortices, part of the associative cortical network. At 12 months, we observe a shift towards decreased connectivity in regions such as the somatosensory cortices, pertaining to the lateral cortical network, and the caudate putamen, a constituent of the subcortical network. Moreover, we assessed the impact of distinct Huntington's Disease-like pathology of the zQ175DN HET mice on age-dependent connectivity between different brain regions and networks where we demonstrate that connectivity strength follows a nonlinear, inverted U-shape pattern, a well-known phenomenon of development and normal aging. Conversely, the neuropathologically driven alteration of connectivity, especially in the default mode and associative cortical networks, showed diminished age-dependent evolution of functional connectivity. These findings reveal that in this Huntington's disease model, altered connectivity starts with cortical network aberrations which precede striatal connectivity changes, that appear only at a later age. Taken together, these results suggest that the age-dependent cortical network dysfunction seen in rodents could represent a relevant pathological process in Huntington's disease progression.
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Affiliation(s)
- Tamara Vasilkovska
- Bio-Imaging Lab, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Antwerp, Belgium; μNEURO Research Centre of Excellence, University of Antwerp, Antwerp, Belgium.
| | - Mohit Adhikari
- Bio-Imaging Lab, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Antwerp, Belgium; μNEURO Research Centre of Excellence, University of Antwerp, Antwerp, Belgium
| | - Johan Van Audekerke
- Bio-Imaging Lab, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Antwerp, Belgium; μNEURO Research Centre of Excellence, University of Antwerp, Antwerp, Belgium
| | - Somaie Salajeghe
- Bio-Imaging Lab, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Antwerp, Belgium
| | | | | | - Haiying Tang
- CHDI Management/CHDI Foundation, Princeton, NJ, USA
| | - Longbin Liu
- CHDI Management/CHDI Foundation, Princeton, NJ, USA
| | | | - Annemie Van der Linden
- Bio-Imaging Lab, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Antwerp, Belgium; μNEURO Research Centre of Excellence, University of Antwerp, Antwerp, Belgium
| | - Marleen Verhoye
- Bio-Imaging Lab, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Antwerp, Belgium; μNEURO Research Centre of Excellence, University of Antwerp, Antwerp, Belgium
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Estrada-Sánchez AM, Rebec GV, Galvan L. Editorial: New insight into Huntington's disease: From neuropathology to possible therapeutic targets. Front Neurosci 2023; 17:1138712. [PMID: 36816128 PMCID: PMC9933495 DOI: 10.3389/fnins.2023.1138712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Accepted: 01/20/2023] [Indexed: 02/05/2023] Open
Affiliation(s)
- Ana María Estrada-Sánchez
- División de Biología Molecular, Laboratorio de Neurobiología, Instituto Potosino de Investigación Científica y Tecnológica (IPICYT), San Luis Potosí, Mexico,*Correspondence: Ana María Estrada-Sánchez ✉
| | - George V. Rebec
- Program in Neuroscience, Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, United States
| | - Laurie Galvan
- Sciences Department, Université de Nîmes, Nîmes, France
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8
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Sepers MD, Mackay JP, Koch E, Xiao D, Mohajerani MH, Chan AW, Smith-Dijak AI, Ramandi D, Murphy TH, Raymond LA. Altered cortical processing of sensory input in Huntington disease mouse models. Neurobiol Dis 2022; 169:105740. [PMID: 35460870 DOI: 10.1016/j.nbd.2022.105740] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 04/10/2022] [Accepted: 04/16/2022] [Indexed: 11/24/2022] Open
Abstract
Huntington disease (HD), a hereditary neurodegenerative disorder, manifests as progressively impaired movement and cognition. Although early abnormalities of neuronal activity in striatum are well established in HD models, there are fewer in vivo studies of the cortex. Here, we record local field potentials (LFPs) in YAC128 HD model mice versus wild-type mice. In multiple cortical areas, limb sensory stimulation evokes a greater change in LFP power in YAC128 mice. Mesoscopic imaging using voltage-sensitive dyes reveals more extensive spread of evoked sensory signals across the cortical surface in YAC128 mice. YAC128 layer 2/3 sensory cortical neurons ex vivo show increased excitatory events, which could contribute to enhanced sensory responses in vivo. Cortical LFP responses to limb stimulation, visual and auditory input are also significantly increased in zQ175 HD mice. Results presented here extend knowledge of HD beyond ex vivo studies of individual neurons to the intact cortical network.
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Affiliation(s)
- Marja D Sepers
- Department of Psychiatry and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC V6T1Z3, Canada
| | - James P Mackay
- Department of Psychiatry and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC V6T1Z3, Canada
| | - Ellen Koch
- Department of Psychiatry and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC V6T1Z3, Canada
| | - Dongsheng Xiao
- Department of Psychiatry and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC V6T1Z3, Canada
| | - Majid H Mohajerani
- Canadian Center for Behavioural Neuroscience, University of Lethbridge, Lethbridge T1K 3M4, Canada
| | - Allan W Chan
- Department of Psychiatry, University of Alberta, Edmonton, AB, Canada
| | - Amy I Smith-Dijak
- Department of Psychiatry and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC V6T1Z3, Canada
| | - Daniel Ramandi
- Department of Psychiatry and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC V6T1Z3, Canada
| | - Timothy H Murphy
- Department of Psychiatry and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC V6T1Z3, Canada
| | - Lynn A Raymond
- Department of Psychiatry and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC V6T1Z3, Canada.
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9
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Callahan JW, Wokosin DL, Bevan MD. Dysregulation of the Basal Ganglia Indirect Pathway in Early Symptomatic Q175 Huntington's Disease Mice. J Neurosci 2022; 42:2080-2102. [PMID: 35058372 PMCID: PMC8916764 DOI: 10.1523/jneurosci.0782-21.2022] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 12/16/2021] [Accepted: 01/11/2022] [Indexed: 11/21/2022] Open
Abstract
The debilitating psychomotor symptoms of Huntington's disease (HD) are linked partly to degeneration of the basal ganglia indirect pathway. At early symptomatic stages, before major cell loss, indirect pathway neurons exhibit numerous cellular and synaptic changes in HD and its models. However, the impact of these alterations on circuit activity remains poorly understood. To address this gap, optogenetic- and reporter-guided electrophysiological interrogation was used in early symptomatic male and female Q175 HD mice. D2 dopamine receptor-expressing striatal projection neurons (D2-SPNs) were hypoactive during synchronous cortical slow-wave activity, consistent with known reductions in dendritic excitability and cortical input strength. Downstream prototypic parvalbumin-expressing external globus pallidus (PV+ GPe) neurons discharged at 2-3 times their normal rate, even during periods of D2-SPN inactivity, arguing that defective striatopallidal inhibition was not the only cause of their hyperactivity. Indeed, PV+ GPe neurons also exhibited abnormally elevated autonomous firing ex vivo Optogenetic inhibition of PV+ GPe neurons in vivo partially and fully ameliorated the abnormal hypoactivity of postsynaptic subthalamic nucleus (STN) and putative PV- GPe neurons, respectively. In contrast to STN neurons whose autonomous firing is impaired in HD mice, putative PV- GPe neuron activity was unaffected ex vivo, implying that excessive inhibition was responsible for their hypoactivity in vivo Together with previous studies, these data demonstrate that (1) indirect pathway nuclei are dysregulated in Q175 mice through changes in presynaptic activity and/or intrinsic cellular and synaptic properties; and (2) prototypic PV+ GPe neuron hyperactivity and excessive target inhibition are prominent features of early HD pathophysiology.SIGNIFICANCE STATEMENT The early symptoms of Huntington's disease (HD) are linked to degenerative changes in the action-suppressing indirect pathway of the basal ganglia. Consistent with this linkage, the intrinsic properties of cells in this pathway exhibit complex alterations in HD and its models. However, the impact of these changes on activity is poorly understood. Using electrophysiological and optogenetic approaches, we demonstrate that the indirect pathway is highly dysregulated in early symptomatic HD mice through changes in upstream activity and/or intrinsic properties. Furthermore, we reveal that hyperactivity of external globus pallidus neurons and excessive inhibition of their targets are key features of early HD pathophysiology. Together, these findings could help to inform the development and targeting of viral-based, gene therapeutic approaches for HD.
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Affiliation(s)
- Joshua W Callahan
- Department of Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
| | - David L Wokosin
- Department of Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
| | - Mark D Bevan
- Department of Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
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10
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Rebec GV, Koceja DM, Bunner KD. Measuring Movement in Health and Disease. Brain Res Bull 2022; 181:167-174. [PMID: 35122899 DOI: 10.1016/j.brainresbull.2022.01.021] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 01/15/2022] [Accepted: 01/29/2022] [Indexed: 01/07/2023]
Abstract
Evaluating and quantifying the many aspects of movement -- from open-field locomotion and stepping patterns in rodent models to stride trajectory and postural sway in human patients -- are key to understanding brain function. Various experimental approaches have been used in applying these lines of research to investigate the brain mechanisms underlying neurodegenerative disease. Although valuable, data on movement are often limited by the shortcomings inherent in the data collection process itself. Steve Fowler and his research group have been instrumental in pioneering a technology that both minimizes these pitfalls in studies of rodent behavior and has applications to research on human patients. At the center of this technology is the force-plate actometer, developed by the Fowler group to assess multiple aspects of movement in rodent models. Our review highlights how use of the actometer and related behavioral measurements provides valuable insight into Huntington's disease (HD), an autosomal dominant condition of progressively deteriorating behavioral control. HD typically emerges in mid-life and has been replicated in multiple genetically engineered mouse models. The actometer also can be a valuable addition to cutting-edge neuronal and synaptic technologies that are now increasingly applied to studies of behaving animals. In short, the impact of the Fowler contribution to the neuroscience of movement is both meaningful and ongoing.
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Affiliation(s)
- George V Rebec
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405, United States; Program in Neuroscience, Indiana University, Bloomington, IN 47405, United States.
| | - David M Koceja
- Department of Kinesiology, Indiana University, Bloomington, IN 47405, United States; Program in Neuroscience, Indiana University, Bloomington, IN 47405, United States
| | - Kendra D Bunner
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405, United States
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11
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Kaye J, Reisine T, Finkbeiner S. Huntington's disease mouse models: unraveling the pathology caused by CAG repeat expansion. Fac Rev 2021; 10:77. [PMID: 34746930 PMCID: PMC8546598 DOI: 10.12703/r/10-77] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Huntington's disease (HD) is a neurodegenerative disease that results in motor and cognitive dysfunction, leading to early death. HD is caused by an expansion of CAG repeats in the huntingtin gene (HTT). Here, we review the mouse models of HD. They have been used extensively to better understand the molecular and cellular basis of disease pathogenesis as well as to provide non-human subjects to test the efficacy of potential therapeutics. The first and best-studied in vivo rodent model of HD is the R6/2 mouse, in which a transgene containing the promoter and exon 1 fragment of human HTT with 150 CAG repeats was inserted into the mouse genome. R6/2 mice express rapid, robust behavioral pathologies and display a number of degenerative abnormalities in neuronal populations most vulnerable in HD. The first conditional full-length mutant huntingtin (mHTT) mouse model of HD was the bacterial artificial chromosome (BAC) transgenic mouse model of HD (BACHD), which expresses human full-length mHTT with a mixture of 97 CAG-CAA repeats under the control of endogenous HTT regulatory machinery. It has been useful in identifying the role of mHTT in specific neuronal populations in degenerative processes. In the knock-in (KI) model of HD, the expanded human CAG repeats and human exon 1 are inserted into the mouse Htt locus, so a chimera of the full-length mouse protein with the N-terminal human portion is expressed. Many of aspects of the pathology and behavioral deficits in the KI model better mimic disease characteristics found in HD patients than other models. Accordingly, some have proposed that these mice may be preferable models of the disease over others. Indeed, as our understanding of HD advances, so will the design of animal models to test and develop HD therapies.
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Affiliation(s)
- Julia Kaye
- Center for Systems and Therapeutics, Gladstone Institutes, San Francisco, CA, USA
| | - Terry Reisine
- Independent Scientific Consultant, Santa Cruz, CA, USA
| | - Steve Finkbeiner
- Center for Systems and Therapeutics, Gladstone Institutes, San Francisco, CA, USA
- Taube/Koret Center for Neurodegenerative Disease Research, Gladstone Institutes, San Francisco, CA, USA
- Department of Neurology and Physiology, University of California, San Francisco, CA, USA
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12
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Oikonomou KD, Donzis EJ, Bui MTN, Cepeda C, Levine MS. Calcium dysregulation and compensation in cortical pyramidal neurons of the R6/2 mouse model of Huntington's disease. J Neurophysiol 2021; 126:1159-1171. [PMID: 34469694 DOI: 10.1152/jn.00181.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Huntington's disease (HD) is a fatal, hereditary neurodegenerative disorder that predominantly affects striatal medium-sized spiny neurons and cortical pyramidal neurons (CPNs). It has been proposed that perturbations in Ca2+ homeostasis could play a role in CPN alterations. To test this hypothesis, we used the R6/2 mouse model of juvenile HD at different stages of disease progression; presymptomatic, early symptomatic, and late symptomatic. We combined whole-cell patch-clamp recordings of layer 2/3 CPNs with two-photon laser scanning microscopy to image somatic and dendritic Ca2+ transients associated with evoked action potentials (APs). We found that the amplitude of AP-induced Ca2+ transients recorded at the somata of CPNs was significantly reduced in presymptomatic and late symptomatic R6/2 mice compared with wild-type (WT) littermates. However, reduced amplitudes were compensated by increases in decay times, so that Ca2+ transient areas were similar between genotypes. AP-induced Ca2+ transients in CPN proximal dendrites were variable and differences did not reach statistical significance, except for reduced areas in the late symptomatic group. In late symptomatic mice, a specific store-operated Ca2+ channel antagonist, EVP4593, reduced somatic Ca2+ transient amplitude similarly in WT and R6/2 CPNs. In contrast, dantrolene, a ryanodine receptor (RyR) antagonist, and nifedipine, an L-type Ca2+ channel blocker, significantly reduced both somatic Ca2+ transient amplitude and area in R6/2 but not WT CPNs. These findings demonstrate that perturbations of Ca2+ homeostasis and compensation occur in CPNs before and after the onset of overt symptoms, and suggest RyRs and L-type Ca2+ channels as potential targets for therapeutic intervention.NEW & NOTEWORTHY We used two-photon microscopy to examine calcium influx induced by action potentials in cortical pyramidal neurons from a mouse model of Huntington's disease (HD), the R6/2. The amplitude of somatic calcium transients was reduced in R6/2 mice compared with controls. This reduction was compensated by increased decay times, which could lead to reduced calcium buffering capacity. L-type calcium channel and ryanodine receptor blockers reduced calcium transient area in HD neurons, suggesting new therapeutic avenues.
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Affiliation(s)
- Katerina D Oikonomou
- IDDRC, Semel Institute for Neuroscience and Human Behavior, Jane and Terry Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, California
| | - Elissa J Donzis
- IDDRC, Semel Institute for Neuroscience and Human Behavior, Jane and Terry Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, California
| | - Minh T N Bui
- IDDRC, Semel Institute for Neuroscience and Human Behavior, Jane and Terry Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, California
| | - Carlos Cepeda
- IDDRC, Semel Institute for Neuroscience and Human Behavior, Jane and Terry Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, California
| | - Michael S Levine
- IDDRC, Semel Institute for Neuroscience and Human Behavior, Jane and Terry Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, California
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13
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Shobe JL, Donzis EJ, Lee K, Chopra S, Masmanidis SC, Cepeda C, Levine MS. Early impairment of thalamocortical circuit activity and coherence in a mouse model of Huntington's disease. Neurobiol Dis 2021; 157:105447. [PMID: 34274461 PMCID: PMC8591983 DOI: 10.1016/j.nbd.2021.105447] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 06/22/2021] [Accepted: 07/13/2021] [Indexed: 10/20/2022] Open
Abstract
Huntington's disease (HD) is a progressive, fatal neurodegenerative disorder characterized by motor, cognitive, and psychiatric disturbances. There is no known cure for HD, but its progressive nature allows for early therapeutic intervention. Currently, much of the research has focused on the striatum, however, there is evidence suggesting that disruption of thalamocortical circuits could underlie some of the early symptoms of HD. Loss of both cortical pyramidal neurons (CPNs) and thalamic neurons occurs in HD patients, and cognitive, somatosensory, and attention deficits precede motor abnormalities. However, the role of thalamocortical pathways in HD progression has been understudied. Here, we measured single unit activity and local field potentials (LFPs) from electrode arrays implanted in the thalamus and primary motor cortex of 4-5 month-old male and female Q175 mice. We assessed neuronal activity under baseline conditions as well as during presentation of rewards delivered via actuation of an audible solenoid valve. HD mice showed a significantly delayed licking response to the reward stimulus. At the same time, neuronal activation to the reward was delayed in thalamic neurons, CPNs and fast-spiking cortical interneurons (FSIs) of HD mice. In addition, thalamocortical coherence increased at lower frequencies in HD relative to wildtype mice. Together, these data provide evidence that impaired cortical and thalamic responses to reward stimuli, and impaired thalamocortical coherence, may play an important early role in motor, cognitive, and learning deficits in HD patients.
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Affiliation(s)
- Justin L Shobe
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, USA
| | - Elissa J Donzis
- Intellectual and Developmental Disabilities Research Center, Jane and Terry Semel Institute for Neuroscience & Human Behavior, University of California Los Angeles, Los Angeles, CA, USA
| | - Kwang Lee
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, South Korea
| | - Samiksha Chopra
- Intellectual and Developmental Disabilities Research Center, Jane and Terry Semel Institute for Neuroscience & Human Behavior, University of California Los Angeles, Los Angeles, CA, USA
| | - Sotiris C Masmanidis
- Department of Neurobiology, University of California Los Angeles, Los Angeles, CA, USA
| | - Carlos Cepeda
- Intellectual and Developmental Disabilities Research Center, Jane and Terry Semel Institute for Neuroscience & Human Behavior, University of California Los Angeles, Los Angeles, CA, USA
| | - Michael S Levine
- Intellectual and Developmental Disabilities Research Center, Jane and Terry Semel Institute for Neuroscience & Human Behavior, University of California Los Angeles, Los Angeles, CA, USA.
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14
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Cheong RY, Baldo B, Sajjad MU, Kirik D, Petersén Å. Effects of mutant huntingtin inactivation on Huntington disease-related behaviours in the BACHD mouse model. Neuropathol Appl Neurobiol 2021; 47:564-578. [PMID: 33330988 PMCID: PMC8247873 DOI: 10.1111/nan.12682] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 10/27/2020] [Accepted: 12/14/2020] [Indexed: 01/02/2023]
Abstract
AIMS Huntington disease (HD) is a fatal neurodegenerative disorder with no disease-modifying treatments approved so far. Ongoing clinical trials are attempting to reduce huntingtin (HTT) expression in the central nervous system (CNS) using different strategies. Yet, the distribution and timing of HTT-lowering therapies required for a beneficial clinical effect is less clear. Here, we investigated whether HD-related behaviours could be prevented by inactivating mutant HTT at different disease stages and to varying degrees in an experimental model. METHODS We generated mutant BACHD mice with either a widespread or circuit-specific inactivation of mutant HTT by using Cre recombinase (Cre) under the nestin promoter or the adenosine A2A receptor promoter respectively. We also simulated a clinical gene therapy scenario with allele-specific HTT targeting by injections of recombinant adeno-associated viral (rAAV) vectors expressing Cre into the striatum of adult BACHD mice. All mice were assessed using behavioural tests to investigate motor, metabolic and psychiatric outcome measures at 4-6 months of age. RESULTS While motor deficits, body weight changes, anxiety and depressive-like behaviours are present in BACHD mice, early widespread CNS inactivation during development significantly improves rotarod performance, body weight changes and depressive-like behaviour. However, conditional circuit-wide mutant HTT deletion from the indirect striatal pathway during development and focal striatal-specific deletion in adulthood failed to rescue any of the HD-related behaviours. CONCLUSIONS Our results indicate that widespread targeting and the timing of interventions aimed at reducing mutant HTT are important factors to consider when developing disease-modifying therapies for HD.
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Affiliation(s)
- Rachel Y. Cheong
- Translational Neuroendocrine Research UnitDepartment of Experimental Medical ScienceLund UniversityLundSweden
| | - Barbara Baldo
- Translational Neuroendocrine Research UnitDepartment of Experimental Medical ScienceLund UniversityLundSweden
- Present address:
Evotec SEHD Research and Translational SciencesHamburgGermany
| | - Muhammad U. Sajjad
- Translational Neuroendocrine Research UnitDepartment of Experimental Medical ScienceLund UniversityLundSweden
| | - Deniz Kirik
- Brain Repair and Imaging in Neural Systems UnitDepartment of Experimental Medical ScienceLund UniversityLundSweden
| | - Åsa Petersén
- Translational Neuroendocrine Research UnitDepartment of Experimental Medical ScienceLund UniversityLundSweden
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15
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Buren C, Tu G, Raymond LA. Impaired Replenishment of Cortico-Striatal Synaptic Glutamate in Huntington's Disease Mouse Model. J Huntingtons Dis 2021; 9:149-161. [PMID: 32310183 DOI: 10.3233/jhd-200400] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
BACKGROUND Huntington's disease (HD) is an inherited neurodegenerative disorder caused by expansion of CAG repeats in the Huntingtin gene (HTT). Studies suggest cortical to striatal (C-S) projections, which regulate movement and provide cell survival signals to SPNs, are altered in the pre-manifest and early symptomatic stages of HD. But whether and how presynaptic cortical terminals are affected in HD is not well explored. OBJECTIVE Test size and replenishment of readily releasable pool (RRP), and assess glutamate refill of C-S synapses in HD models. METHODS Immunocytochemistry was applied in C-S co-cultures generated from FVB/N (WT: wildtype) mice and YAC128, an HD mouse model expressing human HTT with 128 CAG repeats on the FVB/N background; Whole-cell patch clamp recordings from striatal neurons were performed both in cultures, with or without osmotic stimuli, and in acute brain slices from 6-month-old early symptomatic YAC128 mice and WT following prolonged trains of electrical stimuli in corpus callosum. RESULTS We found no change in the average size or vesicle replenishment rate of RRP in C-S synapses of YAC128, compared with WT, cultures at day in vitro 21, a time when immunocytochemistry showed comparable neuronal survival between the two genotypes. However, YAC128 C-S synapses showed a slowed rate of recovery of glutamate release in co-cultures as well as in acute brain slices. CONCLUSION Mutant HTT expression impairs glutamate refill but not RRP size or replenishment in C-S synapses. This work provides a foundation for examining the contribution of deficits in presynaptic cortical terminals on HD progression.
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Affiliation(s)
- Caodu Buren
- Graduate Program in Neuroscience, The University of British Columbia, Vancouver, Canada.,Department of Psychiatry and Djavad Mowafaghian Centre for Brain Health, The University of British Columbia, Vancouver, Canada
| | - Gaqi Tu
- School of Medicine, Zhejiang University, Hangzhou, Zhejiang, China.,Department of Psychology, University of Toronto, Toronto, Ontario, Canada
| | - Lynn A Raymond
- Department of Psychiatry and Djavad Mowafaghian Centre for Brain Health, The University of British Columbia, Vancouver, Canada
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16
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Cepeda C, Levine MS. Synaptic Dysfunction in Huntington's Disease: Lessons from Genetic Animal Models. Neuroscientist 2020; 28:20-40. [PMID: 33198566 DOI: 10.1177/1073858420972662] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The understanding of the functional and structural changes occurring in the cerebral cortex and basal ganglia in Huntington's disease (HD) has benefited considerably from the generation of genetic animal models. Most studies of synaptic alterations in HD models have focused on the striatum, but a more complete picture of synaptic dysfunction in the cortico-basal ganglia-cortical loop is emerging. Here, we provide a review and analysis of current developments in the study of synaptic alterations in these areas using HD rodent models. Recent evidence indicates that cortical maldevelopment plays a role in synaptic dysfunction along the corticostriatal pathway that may have its roots in the way mutant huntingtin interacts with synaptic proteins. Furthermore, a progressive disconnection in the corticostriatal pathway leads to abnormal function engaging extrasynaptic N-methyl-D-aspartate glutamate receptors that contribute to eventual cell degeneration. In addition, biphasic increases followed by decreases in glutamate and dopamine release in the striatum could explain contrasting symptomatology in early and late stages of the disease. Changes in striatal output regions also are beginning to be examined. Finally, we highlight some therapeutic avenues aimed at rescuing synaptic dysfunction.
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Affiliation(s)
- Carlos Cepeda
- IDDRC, Jane and Terry Semel Institute for Neuroscience & Human Behavior, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Michael S Levine
- IDDRC, Jane and Terry Semel Institute for Neuroscience & Human Behavior, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
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17
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Bennett CF, Krainer AR, Cleveland DW. Antisense Oligonucleotide Therapies for Neurodegenerative Diseases. Annu Rev Neurosci 2020; 42:385-406. [PMID: 31283897 DOI: 10.1146/annurev-neuro-070918-050501] [Citation(s) in RCA: 189] [Impact Index Per Article: 47.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Antisense oligonucleotides represent a novel therapeutic platform for the discovery of medicines that have the potential to treat most neurodegenerative diseases. Antisense drugs are currently in development for the treatment of amyotrophic lateral sclerosis, Huntington's disease, and Alzheimer's disease, and multiple research programs are underway for additional neurodegenerative diseases. One antisense drug, nusinersen, has been approved for the treatment of spinal muscular atrophy. Importantly, nusinersen improves disease symptoms when administered to symptomatic patients rather than just slowing the progression of the disease. In addition to the benefit to spinal muscular atrophy patients, there are discoveries from nusinersen that can be applied to other neurological diseases, including method of delivery, doses, tolerability of intrathecally delivered antisense drugs, and the biodistribution of intrathecal dosed antisense drugs. Based in part on the early success of nusinersen, antisense drugs hold great promise as a therapeutic platform for the treatment of neurological diseases.
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Affiliation(s)
| | - Adrian R Krainer
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA
| | - Don W Cleveland
- Ludwig Institute for Cancer Research, University of California, San Diego, La Jolla, California 92093, USA
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18
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Ponzi A, Barton SJ, Bunner KD, Rangel-Barajas C, Zhang ES, Miller BR, Rebec GV, Kozloski J. Striatal network modeling in Huntington's Disease. PLoS Comput Biol 2020; 16:e1007648. [PMID: 32302302 PMCID: PMC7197869 DOI: 10.1371/journal.pcbi.1007648] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 05/04/2020] [Accepted: 01/09/2020] [Indexed: 12/26/2022] Open
Abstract
Medium spiny neurons (MSNs) comprise over 90% of cells in the striatum. In vivo MSNs display coherent burst firing cell assembly activity patterns, even though isolated MSNs do not burst fire intrinsically. This activity is important for the learning and execution of action sequences and is characteristically dysregulated in Huntington's Disease (HD). However, how dysregulation is caused by the various neural pathologies affecting MSNs in HD is unknown. Previous modeling work using simple cell models has shown that cell assembly activity patterns can emerge as a result of MSN inhibitory network interactions. Here, by directly estimating MSN network model parameters from single unit spiking data, we show that a network composed of much more physiologically detailed MSNs provides an excellent quantitative fit to wild type (WT) mouse spiking data, but only when network parameters are appropriate for the striatum. We find the WT MSN network is situated in a regime close to a transition from stable to strongly fluctuating network dynamics. This regime facilitates the generation of low-dimensional slowly varying coherent activity patterns and confers high sensitivity to variations in cortical driving. By re-estimating the model on HD spiking data we discover network parameter modifications are consistent across three very different types of HD mutant mouse models (YAC128, Q175, R6/2). In striking agreement with the known pathophysiology we find feedforward excitatory drive is reduced in HD compared to WT mice, while recurrent inhibition also shows phenotype dependency. We show that these modifications shift the HD MSN network to a sub-optimal regime where higher dimensional incoherent rapidly fluctuating activity predominates. Our results provide insight into a diverse range of experimental findings in HD, including cognitive and motor symptoms, and may suggest new avenues for treatment.
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Affiliation(s)
- Adam Ponzi
- IBM Research, Computational Biology Center, Thomas J. Watson Research Laboratories, Yorktown Heights, New York, United States of America
- * E-mail:
| | - Scott J. Barton
- Program in Neuroscience, Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana, United States of America
| | - Kendra D. Bunner
- Program in Neuroscience, Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana, United States of America
| | - Claudia Rangel-Barajas
- Program in Neuroscience, Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana, United States of America
| | - Emily S. Zhang
- Program in Neuroscience, Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana, United States of America
| | - Benjamin R. Miller
- Program in Neuroscience, Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana, United States of America
| | - George V. Rebec
- Program in Neuroscience, Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana, United States of America
| | - James Kozloski
- IBM Research, Computational Biology Center, Thomas J. Watson Research Laboratories, Yorktown Heights, New York, United States of America
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19
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Donzis EJ, Estrada-Sánchez AM, Indersmitten T, Oikonomou K, Tran CH, Wang C, Latifi S, Golshani P, Cepeda C, Levine MS. Cortical Network Dynamics Is Altered in Mouse Models of Huntington's Disease. Cereb Cortex 2020; 30:2372-2388. [PMID: 31761935 PMCID: PMC7174987 DOI: 10.1093/cercor/bhz245] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 09/05/2019] [Accepted: 09/12/2019] [Indexed: 11/15/2022] Open
Abstract
Huntington's disease (HD) is a neurodegenerative disorder characterized by involuntary movements, cognitive deficits, and psychiatric disturbances. Although evidence indicates that projections from motor cortical areas play a key role in the development of dysfunctional striatal activity and motor phenotype, little is known about the changes in cortical microcircuits and their role in the development of the HD phenotype. Here we used two-photon laser-scanning microscopy to evaluate network dynamics of motor cortical neurons in layers II/III in behaving transgenic R6/2 and knock-in Q175+/- mice. Symptomatic R6/2 mice displayed increased motion manifested by a significantly greater number of motion epochs, whereas symptomatic Q175 mice displayed decreased motion. In both models, calcium transients in symptomatic mice displayed reduced amplitude, suggesting decreased bursting activity. Changes in frequency were genotype- and time-dependent; for R6/2 mice, the frequency was reduced during both motion and nonmotion, whereas in symptomatic Q175 mice, the reduction only occurred during nonmotion. In presymptomatic Q175 mice, frequency was increased during both behavioral states. Interneuronal correlation coefficients were generally decreased in both models, suggesting disrupted interneuronal communication in HD cerebral cortex. These results indicate similar and contrasting effects of the HD mutation on cortical ensemble activity depending on mouse model and disease stage.
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Affiliation(s)
- Elissa J Donzis
- Intellectual and Developmental Disabilities Research Center, Jane and Terry Semel Institute for Neuroscience & Human Behavior
| | - Ana María Estrada-Sánchez
- Intellectual and Developmental Disabilities Research Center, Jane and Terry Semel Institute for Neuroscience & Human Behavior
| | - Tim Indersmitten
- Intellectual and Developmental Disabilities Research Center, Jane and Terry Semel Institute for Neuroscience & Human Behavior
| | - Katerina Oikonomou
- Intellectual and Developmental Disabilities Research Center, Jane and Terry Semel Institute for Neuroscience & Human Behavior
| | - Conny H Tran
- Intellectual and Developmental Disabilities Research Center, Jane and Terry Semel Institute for Neuroscience & Human Behavior
| | - Catherine Wang
- Intellectual and Developmental Disabilities Research Center, Jane and Terry Semel Institute for Neuroscience & Human Behavior
| | - Shahrzad Latifi
- Department of Neurology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Peyman Golshani
- Intellectual and Developmental Disabilities Research Center, Jane and Terry Semel Institute for Neuroscience & Human Behavior
- Department of Neurology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
- Department of Neurology, West Los Angeles VA Medical Center, Los Angeles, CA 90073, USA
| | - Carlos Cepeda
- Intellectual and Developmental Disabilities Research Center, Jane and Terry Semel Institute for Neuroscience & Human Behavior
| | - Michael S Levine
- Intellectual and Developmental Disabilities Research Center, Jane and Terry Semel Institute for Neuroscience & Human Behavior
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20
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Petkau TL, Hill A, Connolly C, Lu G, Wagner P, Kosior N, Blanco J, Leavitt BR. Mutant huntingtin expression in microglia is neither required nor sufficient to cause the Huntington's disease-like phenotype in BACHD mice. Hum Mol Genet 2020; 28:1661-1670. [PMID: 30624705 DOI: 10.1093/hmg/ddz009] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Revised: 12/10/2018] [Accepted: 12/31/2018] [Indexed: 12/27/2022] Open
Abstract
Huntington's disease (HD) is caused by a CAG repeat expansion in the HTT gene and is characterized by early and selective striatal neurodegeneration. The huntingtin (HTT) protein is ubiquitously expressed in many tissues and the cellular pathogenesis of the disease is not fully understood. Immune cell dysfunction due to mutant HTT (mHTT) expression and aberrant immune system activation in HD patients suggests that inflammatory processes may contribute to HD pathogenesis. Here we used the BACHD mouse model of HD, which carries a conditional transgene expressing full-length human mHTT, to selectively deplete mHTT expression in myeloid lineage cells, including microglia, and evaluated the effects on HD-related behavior and neuropathology. In the converse experiment, we depleted mHTT expression in the majority of cells in the brain but specifically excluding microglia and again evaluated behavior and neuropathology. In mice with myeloid-specific mHTT-depletion, we observed no significant rescue of any behavioral or neuropathological outcome measures, while neural-specific knockout mice showed significant rescue of body weight, rotarod performance and striatal volume. We conclude that mHTT expression in microglia, though clearly affecting specific aspects of microglia function, does not alter disease pathogenesis in the BACHD mouse model. This may have implications for current or future therapeutic trials testing immune-modulating drugs in HD patients.
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Affiliation(s)
- Terri L Petkau
- Centre for Molecular Medicine & Therapeutics, Department of Medical Genetics, University of British Columbia, and Children's and Women's Hospital, Vancouver, BC, Canada
| | - Austin Hill
- Centre for Molecular Medicine & Therapeutics, Department of Medical Genetics, University of British Columbia, and Children's and Women's Hospital, Vancouver, BC, Canada
| | - Colúm Connolly
- Centre for Molecular Medicine & Therapeutics, Department of Medical Genetics, University of British Columbia, and Children's and Women's Hospital, Vancouver, BC, Canada
| | - Ge Lu
- Centre for Molecular Medicine & Therapeutics, Department of Medical Genetics, University of British Columbia, and Children's and Women's Hospital, Vancouver, BC, Canada
| | - Pam Wagner
- Centre for Molecular Medicine & Therapeutics, Department of Medical Genetics, University of British Columbia, and Children's and Women's Hospital, Vancouver, BC, Canada
| | - Natalia Kosior
- Centre for Molecular Medicine & Therapeutics, Department of Medical Genetics, University of British Columbia, and Children's and Women's Hospital, Vancouver, BC, Canada
| | - Jake Blanco
- Centre for Molecular Medicine & Therapeutics, Department of Medical Genetics, University of British Columbia, and Children's and Women's Hospital, Vancouver, BC, Canada
| | - Blair R Leavitt
- Centre for Molecular Medicine & Therapeutics, Department of Medical Genetics, University of British Columbia, and Children's and Women's Hospital, Vancouver, BC, Canada.,Division of Neurology, Department of Medicine, University of British Columbia Hospital, Wesbrook Mall, Vancouver, BC, Canada.,Brain Research Centre, University of British Columbia, Vancouver, BC, Canada
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21
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Comella Bolla A, Valente T, Miguez A, Brito V, Gines S, Solà C, Straccia M, Canals JM. CD200 is up-regulated in R6/1 transgenic mouse model of Huntington's disease. PLoS One 2019; 14:e0224901. [PMID: 31790427 PMCID: PMC6886799 DOI: 10.1371/journal.pone.0224901] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Accepted: 10/23/2019] [Indexed: 01/17/2023] Open
Abstract
In Huntington's disease (HD), striatal medium spiny neurons (MSNs) are particularly sensitive to the presence of a CAG repeat in the huntingtin (HTT) gene. However, there are many evidences that cells from the peripheral immune system and central nervous system (CNS) immune cells, namely microglia, play an important role in the etiology and the progression of HD. However, it remains unclear whether MSNs neurodegeneration is mediated by a non-cell autonomous mechanism. The homeostasis in the healthy CNS is maintained by several mechanisms of interaction between all brain cells. Neurons can control microglia activation through several inhibitory mechanisms, such as the CD200-CD200R1 interaction. Due to the complete lack of knowledge about the CD200-CD200R1 system in HD, we determined the temporal patterns of CD200 and CD200R1 expression in the neocortex, hippocampus and striatum in the HD mouse models R6/1 and HdhQ111/7 from pre-symptomatic to manifest stages. In order to explore any alteration in the peripheral immune system, we also studied the levels of expression of CD200 and CD200R1 in whole blood. Although CD200R1 expression was not altered, we observed and increase in CD200 gene expression and protein levels in the brain parenchyma of all the regions we examined, along with HD pathogenesis in R6/1 mice. Interestingly, the expression of CD200 mRNA was also up-regulated in blood following a similar temporal pattern. These results suggest that canonical neuronal-microglial communication through CD200-CD200R1 interaction is not compromised, and CD200 up-regulation in R6/1 brain parenchyma could represent a neurotrophic signal to sustain or extend neuronal function in the latest stages of HD as pro-survival mechanism.
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Affiliation(s)
- Andrea Comella Bolla
- Stem Cells and Regenerative Medicine Laboratory, Production and Validation Center of Advanced Therapies (Creatio), Department of Biomedicine, Faculty of Medicine and Health Science, University of Barcelona, Barcelona, Spain
- Neuroscience Institute, University of Barcelona, Barcelona, Spain
- August Pi i Sunyer Biomedical Research Institute (IDIBAPS), Barcelona, Spain
- Network Center for Biomedical Research in Neurodegenerative Diseases (CIBERNED), Madrid, Spain
| | - Tony Valente
- August Pi i Sunyer Biomedical Research Institute (IDIBAPS), Barcelona, Spain
- Department of Cerebral Ischemia and Neurodegeneration, Institut d’Investigacions Biomèdiques de Barcelona–Consejo Superior de Investigaciones Científicas (IIBB–CSIC), Barcelona, Spain
| | - Andres Miguez
- Stem Cells and Regenerative Medicine Laboratory, Production and Validation Center of Advanced Therapies (Creatio), Department of Biomedicine, Faculty of Medicine and Health Science, University of Barcelona, Barcelona, Spain
- Neuroscience Institute, University of Barcelona, Barcelona, Spain
- August Pi i Sunyer Biomedical Research Institute (IDIBAPS), Barcelona, Spain
- Network Center for Biomedical Research in Neurodegenerative Diseases (CIBERNED), Madrid, Spain
| | - Veronica Brito
- Neuroscience Institute, University of Barcelona, Barcelona, Spain
- August Pi i Sunyer Biomedical Research Institute (IDIBAPS), Barcelona, Spain
- Department of Biomedicine, Faculty of Medicine and Health Science, University of Barcelona, Barcelona, Spain
| | - Silvia Gines
- Neuroscience Institute, University of Barcelona, Barcelona, Spain
- August Pi i Sunyer Biomedical Research Institute (IDIBAPS), Barcelona, Spain
- Department of Biomedicine, Faculty of Medicine and Health Science, University of Barcelona, Barcelona, Spain
| | - Carme Solà
- August Pi i Sunyer Biomedical Research Institute (IDIBAPS), Barcelona, Spain
- Department of Cerebral Ischemia and Neurodegeneration, Institut d’Investigacions Biomèdiques de Barcelona–Consejo Superior de Investigaciones Científicas (IIBB–CSIC), Barcelona, Spain
| | - Marco Straccia
- Stem Cells and Regenerative Medicine Laboratory, Production and Validation Center of Advanced Therapies (Creatio), Department of Biomedicine, Faculty of Medicine and Health Science, University of Barcelona, Barcelona, Spain
- Neuroscience Institute, University of Barcelona, Barcelona, Spain
- August Pi i Sunyer Biomedical Research Institute (IDIBAPS), Barcelona, Spain
- Network Center for Biomedical Research in Neurodegenerative Diseases (CIBERNED), Madrid, Spain
| | - Josep M. Canals
- Stem Cells and Regenerative Medicine Laboratory, Production and Validation Center of Advanced Therapies (Creatio), Department of Biomedicine, Faculty of Medicine and Health Science, University of Barcelona, Barcelona, Spain
- Neuroscience Institute, University of Barcelona, Barcelona, Spain
- August Pi i Sunyer Biomedical Research Institute (IDIBAPS), Barcelona, Spain
- Network Center for Biomedical Research in Neurodegenerative Diseases (CIBERNED), Madrid, Spain
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22
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Cepeda C, Oikonomou KD, Cummings D, Barry J, Yazon VW, Chen DT, Asai J, Williams CK, Vinters HV. Developmental origins of cortical hyperexcitability in Huntington's disease: Review and new observations. J Neurosci Res 2019; 97:1624-1635. [PMID: 31353533 PMCID: PMC6801077 DOI: 10.1002/jnr.24503] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 07/12/2019] [Accepted: 07/15/2019] [Indexed: 12/13/2022]
Abstract
Huntington's disease (HD), an inherited neurodegenerative disorder that principally affects striatum and cerebral cortex, is generally thought to have an adult onset. However, a small percentage of cases develop symptoms before 20 years of age. This juvenile variant suggests that brain development may be altered in HD. Indeed, recent evidence supports an important role of normal huntingtin during embryonic brain development and mutations in this protein cause cortical abnormalities. Functional studies also demonstrated that the cerebral cortex becomes hyperexcitable with disease progression. In this review, we examine clinical and experimental evidence that cortical development is altered in HD. We also provide preliminary evidence that cortical pyramidal neurons from R6/2 mice, a model of juvenile HD, are hyperexcitable and display dysmorphic processes as early as postnatal day 7. Further, some symptomatic mice present with anatomical abnormalities reminiscent of human focal cortical dysplasia, which could explain the occurrence of epileptic seizures in this genetic mouse model and in children with juvenile HD. Finally, we discuss recent treatments aimed at correcting abnormal brain development.
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Affiliation(s)
- Carlos Cepeda
- IDDRC, Jane and Terry Semel Institute for Neuroscience and Human Behavior and Department of Neurology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Katerina D. Oikonomou
- IDDRC, Jane and Terry Semel Institute for Neuroscience and Human Behavior and Department of Neurology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Damian Cummings
- IDDRC, Jane and Terry Semel Institute for Neuroscience and Human Behavior and Department of Neurology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Joshua Barry
- IDDRC, Jane and Terry Semel Institute for Neuroscience and Human Behavior and Department of Neurology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Vannah-Wila Yazon
- IDDRC, Jane and Terry Semel Institute for Neuroscience and Human Behavior and Department of Neurology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Dickson T. Chen
- IDDRC, Jane and Terry Semel Institute for Neuroscience and Human Behavior and Department of Neurology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Janelle Asai
- IDDRC, Jane and Terry Semel Institute for Neuroscience and Human Behavior and Department of Neurology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Christopher K. Williams
- Section of Neuropathology, Department of Pathology and Laboratory Medicine and Department of Neurology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - Harry V. Vinters
- Section of Neuropathology, Department of Pathology and Laboratory Medicine and Department of Neurology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
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23
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Estrada-Sánchez AM, Blake CL, Barton SJ, Howe AG, Rebec GV. Lack of mutant huntingtin in cortical efferents improves behavioral inflexibility and corticostriatal dynamics in Huntington's disease mice. J Neurophysiol 2019; 122:2621-2629. [PMID: 31693428 DOI: 10.1152/jn.00777.2018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Abnormal communication between cerebral cortex and striatum plays a major role in the motor symptoms of Huntington's disease (HD), a neurodegenerative disorder caused by a mutation of the huntingtin gene (mHTT). Because cortex is the main driver of striatal processing, we recorded local field potential (LFP) activity simultaneously in primary motor cortex (M1) and dorsal striatum (DS) in BACHD mice, a full-length HD gene model, and in a conditional BACHD/Emx-1 Cre (BE) model in which mHTT is suppressed in cortical efferents, while mice freely explored a plus-shaped maze beginning at 20 wk of age. Relative to wild-type (WT) controls, BACHD mice were just as active across >40 wk of testing but became progressively less likely to turn into a perpendicular arm as they approached the choice point of the maze, a sign of HD motor inflexibility. BE mice, in contrast, turned as freely as WT throughout testing. Although BE mice did not exactly match WT in LFP activity, the reduction in alpha (8-13 Hz), beta (13-30 Hz), and low-gamma (30-50 Hz) power that occurred in M1 of turning-impaired BACHD mice was reversed. No reversal occurred in DS. In fact, BE mice showed further reductions in DS theta (4-8 Hz), beta, and low-gamma power relative to the BACHD model. Coherence analysis indicated a dysregulation of corticostriatal information flow in both BACHD and BE mice. Collectively, our results suggest that mHTT in cortical outputs drives the dysregulation of select cortical frequencies that accompany the loss of behavioral flexibility in HD.NEW & NOTEWORTHY BACHD mice, a full-length genetic model of Huntington's disease (HD), express aberrant local field potential (LFP) activity in primary motor cortex (M1) along with decreased probability of turning into a perpendicular arm of a plus-shaped maze, a motor inflexibility phenotype. Suppression of the mutant huntingtin gene in cortical output neurons prevents decline in turning and improves alpha, beta, and low-gamma activity in M1. Our results implicate cortical networks in the search for therapeutic strategies to alleviate HD motor signs.
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Affiliation(s)
- Ana María Estrada-Sánchez
- Program in Neuroscience and Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana.,Departmento de Biología Molecular, Instituto Potosino De Investigación Científica y Tecnológica, San Luis Potosí, Mexico
| | - Courtney L Blake
- Program in Neuroscience and Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana
| | - Scott J Barton
- Program in Neuroscience and Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana
| | - Andrew G Howe
- Neuroscience Interdepartmental Program, University of California, Los Angeles, California.,Department of Psychology, University of California, Los Angeles, California
| | - George V Rebec
- Program in Neuroscience and Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana
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24
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Creus-Muncunill J, Ehrlich ME. Cell-Autonomous and Non-cell-Autonomous Pathogenic Mechanisms in Huntington's Disease: Insights from In Vitro and In Vivo Models. Neurotherapeutics 2019; 16:957-978. [PMID: 31529216 PMCID: PMC6985401 DOI: 10.1007/s13311-019-00782-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Huntington's disease (HD) is an autosomal dominant disorder caused by an expansion in the trinucleotide CAG repeat in exon-1 in the huntingtin gene, located on chromosome 4. When the number of trinucleotide CAG exceeds 40 repeats, disease invariably is manifested, characterized by motor, cognitive, and psychiatric symptoms. The huntingtin (Htt) protein and its mutant form (mutant huntingtin, mHtt) are ubiquitously expressed but although multiple brain regions are affected, the most vulnerable brain region is the striatum. Striatal medium-sized spiny neurons (MSNs) preferentially degenerate, followed by the cortical pyramidal neurons located in layers V and VI. Proposed HD pathogenic mechanisms include, but are not restricted to, excitotoxicity, neurotrophic support deficits, collapse of the protein degradation mechanisms, mitochondrial dysfunction, transcriptional alterations, and disorders of myelin. Studies performed in cell type-specific and regionally selective HD mouse models implicate both MSN cell-autonomous properties and cell-cell interactions, particularly corticostriatal but also with non-neuronal cell types. Here, we review the intrinsic properties of MSNs that contribute to their selective vulnerability and in addition, we discuss how astrocytes, microglia, and oligodendrocytes, together with aberrant corticostriatal connectivity, contribute to HD pathophysiology. In addition, mHtt causes cell-autonomous dysfunction in cell types other than MSNs. These findings have implications in terms of therapeutic strategies aimed at preventing neuronal dysfunction and degeneration.
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Affiliation(s)
- Jordi Creus-Muncunill
- Department of Neurology, Icahn School of Medicine at Mount Sinai, 1468 Madison Avenue, New York, NY, 10029, USA
| | - Michelle E Ehrlich
- Department of Neurology, Icahn School of Medicine at Mount Sinai, 1468 Madison Avenue, New York, NY, 10029, USA.
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25
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Smith‐Dijak AI, Sepers MD, Raymond LA. Alterations in synaptic function and plasticity in Huntington disease. J Neurochem 2019; 150:346-365. [DOI: 10.1111/jnc.14723] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2018] [Revised: 03/28/2019] [Accepted: 05/08/2019] [Indexed: 12/27/2022]
Affiliation(s)
- Amy I. Smith‐Dijak
- Graduate Program in Neuroscience the University of British Columbia Vancouver British Columbia Canada
- Department of Psychiatry and Djavad Mowafaghian Centre for Brain Health the University of British Columbia Vancouver British Columbia Canada
| | - Marja D. Sepers
- Department of Psychiatry and Djavad Mowafaghian Centre for Brain Health the University of British Columbia Vancouver British Columbia Canada
| | - Lynn A. Raymond
- Department of Psychiatry and Djavad Mowafaghian Centre for Brain Health the University of British Columbia Vancouver British Columbia Canada
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26
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Smith-Dijak AI, Nassrallah WB, Zhang LYJ, Geva M, Hayden MR, Raymond LA. Impairment and Restoration of Homeostatic Plasticity in Cultured Cortical Neurons From a Mouse Model of Huntington Disease. Front Cell Neurosci 2019; 13:209. [PMID: 31156395 PMCID: PMC6532531 DOI: 10.3389/fncel.2019.00209] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2018] [Accepted: 04/24/2019] [Indexed: 12/20/2022] Open
Abstract
Huntington disease (HD) is an inherited neurodegenerative disorder caused by a mutation in the huntingtin gene. The onset of symptoms is preceded by synaptic dysfunction. Homeostatic synaptic plasticity (HSP) refers to processes that maintain the stability of networks of neurons, thought to be required to enable new learning and cognitive flexibility. One type of HSP is synaptic scaling, in which the strength of all of the synapses onto a cell increases or decreases following changes in the cell’s level of activity. Several pathways implicated in synaptic scaling are dysregulated in HD, including brain-derived neurotrophic factor (BDNF) and calcium signaling. Here, we investigated whether HSP is disrupted in cortical neurons from an HD mouse model. We treated cultured cortical neurons from wild-type (WT) FVB/N or YAC128 HD mice with tetrodotoxin (TTX) for 48 h to silence action potentials and then recorded miniature excitatory postsynaptic currents. In WT cultures, these increased in both amplitude and frequency after TTX treatment, and further experiments showed that this was a result of insertion of AMPA receptors and formation of new synapses, respectively. Manipulation of BDNF concentration in the culture medium revealed that BDNF signaling contributed to these changes. In contrast to WT cortical neurons, YAC128 cultures showed no response to action potential silencing. Strikingly, we were able to restore the TTX-induced changes in YAC128 cultures by treating them with pridopidine, a drug which enhances BDNF signaling through stimulation of the sigma-1 receptor (S1R), and with the S1R agonist 3-PPP. These data provide evidence for disruption of HSP in cortical neurons from an HD mouse model that is restored by stimulation of S1R. Our results suggest a potential new direction for developing therapy to mitigate cognitive deficits in HD.
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Affiliation(s)
- Amy I Smith-Dijak
- Graduate Program in Neuroscience, The University of British Columbia, Vancouver, BC, Canada.,Department of Psychiatry, Djavad Mowafaghian Centre for Brain Health, The University of British Columbia, Vancouver, BC, Canada
| | - Wissam B Nassrallah
- Graduate Program in Neuroscience, The University of British Columbia, Vancouver, BC, Canada.,Department of Psychiatry, Djavad Mowafaghian Centre for Brain Health, The University of British Columbia, Vancouver, BC, Canada
| | - Lily Y J Zhang
- Department of Psychiatry, Djavad Mowafaghian Centre for Brain Health, The University of British Columbia, Vancouver, BC, Canada
| | - Michal Geva
- Research and Development, Teva Pharmaceutical Industries Ltd., Netanya, Israel
| | - Michael R Hayden
- Research and Development, Teva Pharmaceutical Industries Ltd., Netanya, Israel.,Centre for Molecular Medicine and Therapeutics, The University of British Columbia, Vancouver, BC, Canada
| | - Lynn A Raymond
- Department of Psychiatry, Djavad Mowafaghian Centre for Brain Health, The University of British Columbia, Vancouver, BC, Canada
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27
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Burgold J, Schulz-Trieglaff EK, Voelkl K, Gutiérrez-Ángel S, Bader JM, Hosp F, Mann M, Arzberger T, Klein R, Liebscher S, Dudanova I. Cortical circuit alterations precede motor impairments in Huntington's disease mice. Sci Rep 2019; 9:6634. [PMID: 31036840 PMCID: PMC6488584 DOI: 10.1038/s41598-019-43024-w] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 04/12/2019] [Indexed: 12/15/2022] Open
Abstract
Huntington's disease (HD) is a devastating hereditary movement disorder, characterized by degeneration of neurons in the striatum and cortex. Studies in human patients and mouse HD models suggest that disturbances of neuronal function in the neocortex play an important role in disease onset and progression. However, the precise nature and time course of cortical alterations in HD have remained elusive. Here, we use chronic in vivo two-photon calcium imaging to longitudinally monitor the activity of identified single neurons in layer 2/3 of the primary motor cortex in awake, behaving R6/2 transgenic HD mice and wildtype littermates. R6/2 mice show age-dependent changes in cortical network function, with an increase in activity that affects a large fraction of cells and occurs rather abruptly within one week, preceeding the onset of motor defects. Furthermore, quantitative proteomics demonstrate a pronounced downregulation of synaptic proteins in the cortex, and histological analyses in R6/2 mice and human HD autopsy cases reveal a reduction in perisomatic inhibitory synaptic contacts on layer 2/3 pyramidal cells. Taken together, our study provides a time-resolved description of cortical network dysfunction in behaving HD mice and points to disturbed excitation/inhibition balance as an important pathomechanism in HD.
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Affiliation(s)
- Johanna Burgold
- Department of Molecules - Signaling - Development, Max Planck Institute of Neurobiology, 82152, Martinsried, Germany
| | | | - Kerstin Voelkl
- Department of Molecules - Signaling - Development, Max Planck Institute of Neurobiology, 82152, Martinsried, Germany
| | - Sara Gutiérrez-Ángel
- Department of Molecules - Signaling - Development, Max Planck Institute of Neurobiology, 82152, Martinsried, Germany
| | - Jakob Maximilian Bader
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, 82152, Martinsried, Germany
| | - Fabian Hosp
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, 82152, Martinsried, Germany
| | - Matthias Mann
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, 82152, Martinsried, Germany
| | - Thomas Arzberger
- German Center for Neurodegenerative Diseases (DZNE), 81377, Munich, Germany
- Center for Neuropathology and Prion Research, Ludwig-Maximilians University Munich, 81377, Munich, Germany
- Department of Psychiatry and Psychotherapy, Ludwig-Maximilians University Munich, 81377, Munich, Germany
| | - Rüdiger Klein
- Department of Molecules - Signaling - Development, Max Planck Institute of Neurobiology, 82152, Martinsried, Germany.
- Munich Cluster for Systems Neurology (SyNergy), 81377, Munich, Germany.
| | - Sabine Liebscher
- Munich Cluster for Systems Neurology (SyNergy), 81377, Munich, Germany.
- Institute of Clinical Neuroimmunology, Klinikum der Universität München, Ludwig-Maximilians University Munich, 82152, Martinsried, Germany.
- Biomedical Center, Medical Faculty, Ludwig-Maximilians University Munich, 82152, Martinsried, Germany.
| | - Irina Dudanova
- Department of Molecules - Signaling - Development, Max Planck Institute of Neurobiology, 82152, Martinsried, Germany.
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28
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Rangel-Barajas C, Rebec GV. Overview of Huntington's Disease Models: Neuropathological, Molecular, and Behavioral Differences. ACTA ACUST UNITED AC 2019; 83:e47. [PMID: 30040221 DOI: 10.1002/cpns.47] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Transgenic mouse models of Huntington's disease (HD), a neurodegenerative condition caused by a single gene mutation, have been transformative in their ability to reveal the molecular processes and pathophysiological mechanisms underlying the HD behavioral phenotype. Three model categories have been generated depending on the genetic context in which the mutation is expressed: truncated, full-length, and knock-in. No single model, however, broadly replicates the behavioral symptoms and massive neuronal loss that occur in human patients. The disparity between model and patient requires careful consideration of what each model has to offer when testing potential treatments. Although the translation of animal data to the clinic has been limited, each model can make unique contributions toward an improved understanding of the neurobehavioral underpinnings of HD. Thus, conclusions based on data obtained from more than one model are likely to have the most success in the search for new treatment targets. © 2018 by John Wiley & Sons, Inc.
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Affiliation(s)
- Claudia Rangel-Barajas
- Program in Neuroscience, Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana
| | - George V Rebec
- Program in Neuroscience, Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana
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29
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Kaemmerer WF, Grondin RC. The effects of huntingtin-lowering: what do we know so far? Degener Neurol Neuromuscul Dis 2019; 9:3-17. [PMID: 30881191 PMCID: PMC6413743 DOI: 10.2147/dnnd.s163808] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Therapies targeting mutant huntingtin DNA, mRNA, and protein have a chance at becoming the first disease-modifying treatments for Huntington’s disease, a fatal inherited neurodegenerative disorder for which only symptom management treatments are available today. This review focuses on evidence addressing several key questions pertinent to huntingtin-lowering, ranging from the functions of wild-type huntingtin (wtHTT) that may be disrupted by huntingtin-lowering treatments through the various ways huntingtin can be lowered, the tolerability of wtHTT-lowering in mice and primates, what has been found in the Ionis Pharmaceutical safety trial of a huntingtin-lowering therapy, and to the question of how much mutant huntingtin may need to be lowered for a therapy to be clinically effective. We conclude that adverse consequences of lowering wtHTT in animals appear to be brain region-specific, and/or dependent upon the animal’s stage of development and the amount by which huntingtin is lowered. Therefore, safe approaches to huntingtin-lowering in patients may be to lower huntingtin only moderately, or lower huntingtin only in the most affected brain regions, or lower huntingtin allele-selectively, or all of the above. Many additional questions about huntingtin-lowering remain open, and will only be answered by upcoming clinical trials, such as whether the delivery approaches currently planned will be adequate to get the treatment to the necessary brain regions, and whether non-allele-selective huntingtin-lowering will be safe in the long run. Meantime, there is a role for preclinical research to address key knowledge gaps, including the effects of non-allele-selective huntingtin-lowering on protein trafficking and viability at the cellular level, the tolerability of wtHTT-lowering in the corticostriatal connections of the primate brain, and the effects of this lowering on the functioning of neurotransmitter systems and the transport of neurotrophic factors to the striatum.
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Affiliation(s)
| | - Richard C Grondin
- Department of Neuroscience, University of Kentucky Medical Center, Lexington, KY, USA,
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30
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Tabrizi SJ, Ghosh R, Leavitt BR. Huntingtin Lowering Strategies for Disease Modification in Huntington's Disease. Neuron 2019; 101:801-819. [PMID: 30844400 DOI: 10.1016/j.neuron.2019.01.039] [Citation(s) in RCA: 164] [Impact Index Per Article: 32.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 12/21/2018] [Accepted: 01/17/2019] [Indexed: 12/24/2022]
Abstract
Huntington's disease is caused by an abnormally expanded CAG repeat expansion in the HTT gene, which confers a predominant toxic gain of function in the mutant huntingtin (mHTT) protein. There are currently no disease-modifying therapies available, but approaches that target proximally in disease pathogenesis hold great promise. These include DNA-targeting techniques such as zinc-finger proteins, transcription activator-like effector nucleases, and CRISPR/Cas9; post-transcriptional huntingtin-lowering approaches such as RNAi, antisense oligonucleotides, and small-molecule splicing modulators; and novel methods to clear the mHTT protein, such as proteolysis-targeting chimeras. Improvements in the delivery and distribution of such agents as well as the development of objective biomarkers of disease and of HTT lowering pharmacodynamic outcomes have brought these potential therapies to the forefront of Huntington's disease research, with clinical trials in patients already underway.
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Affiliation(s)
- Sarah J Tabrizi
- Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, UK; UK Dementia Research Institute (DRI) at UCL, London, UK.
| | - Rhia Ghosh
- Huntington's Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Blair R Leavitt
- UBC Centre for Huntington's Disease, Department of Medical Genetics and Centre for Molecular Medicine and Therapeutics, BC Children's Hospital, University of British Columbia, Vancouver, BC, Canada
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31
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Estrada-Sánchez AM, Castro D, Portillo-Ortiz K, Jang K, Nedjat-Haiem M, Levine MS, Cepeda C. Complete but not partial inhibition of glutamate transporters exacerbates cortical excitability in the R6/2 mouse model of Huntington's disease. CNS Neurosci Ther 2018; 25:509-518. [PMID: 30311425 DOI: 10.1111/cns.13070] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 09/05/2018] [Accepted: 09/07/2018] [Indexed: 01/05/2023] Open
Abstract
AIM Deficient glutamate reuptake occurs in the cerebral cortex of Huntington's disease (HD) patients and murine models. Here, we examine the effects of partial or complete blockade of glutamate transporters on excitatory postsynaptic currents (EPSCs) of cortical pyramidal neurons (CPNs). METHODS Whole-cell patch clamp recordings of CPNs in slices from symptomatic R6/2 mice and wild-type (WT) littermates were used to examine the effects of selective or concurrent inhibition of glutamate reuptake transporters. RESULTS Selective inhibition of the glial glutamate transporter 1 (GLT-1) or the glutamate aspartate transporter (GLAST) produced slight decreases in decay time of evoked EPSCs in CPNs from WT and R6/2 mice with no significant differences between genotypes. In contrast, concurrent inhibition of both transporters with DL-TBOA induced a significant increase in area and decay time and this effect was significantly greater in R6/2 CPNs. Furthermore, full blockade also reduced spontaneous EPSC frequency and exacerbated epileptiform activity in CPNs from symptomatic R6/2 mice. CONCLUSIONS R6/2 CPNs are more sensitive to glutamate accumulation during full inhibition of both glutamate transporters, and these neurons have homeostatic mechanisms to cope with inhibition of GLT-1 or GLAST by a mechanism that involves upregulation of either transporter when the other is deficient.
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Affiliation(s)
- Ana María Estrada-Sánchez
- Intellectual and Developmental Disabilities Research Center, David Geffen School of Medicine, Semel Institute for Neuroscience & Human Behavior, University of California Los Angeles, Los Angeles, California
| | - Daniel Castro
- Intellectual and Developmental Disabilities Research Center, David Geffen School of Medicine, Semel Institute for Neuroscience & Human Behavior, University of California Los Angeles, Los Angeles, California
| | - Kenia Portillo-Ortiz
- Intellectual and Developmental Disabilities Research Center, David Geffen School of Medicine, Semel Institute for Neuroscience & Human Behavior, University of California Los Angeles, Los Angeles, California
| | - Katrina Jang
- Intellectual and Developmental Disabilities Research Center, David Geffen School of Medicine, Semel Institute for Neuroscience & Human Behavior, University of California Los Angeles, Los Angeles, California
| | - Michael Nedjat-Haiem
- Intellectual and Developmental Disabilities Research Center, David Geffen School of Medicine, Semel Institute for Neuroscience & Human Behavior, University of California Los Angeles, Los Angeles, California
| | - Michael S Levine
- Intellectual and Developmental Disabilities Research Center, David Geffen School of Medicine, Semel Institute for Neuroscience & Human Behavior, University of California Los Angeles, Los Angeles, California
| | - Carlos Cepeda
- Intellectual and Developmental Disabilities Research Center, David Geffen School of Medicine, Semel Institute for Neuroscience & Human Behavior, University of California Los Angeles, Los Angeles, California
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32
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Ruiz-Calvo A, Maroto IB, Bajo-Grañeras R, Chiarlone A, Gaudioso Á, Ferrero JJ, Resel E, Sánchez-Prieto J, Rodríguez-Navarro JA, Marsicano G, Galve-Roperh I, Bellocchio L, Guzmán M. Pathway-Specific Control of Striatal Neuron Vulnerability by Corticostriatal Cannabinoid CB1 Receptors. Cereb Cortex 2018; 28:307-322. [PMID: 29121220 DOI: 10.1093/cercor/bhx285] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Indexed: 01/08/2023] Open
Abstract
The vast majority of neurons within the striatum are GABAergic medium spiny neurons (MSNs), which receive glutamatergic input from the cortex and thalamus, and form two major efferent pathways: the direct pathway, expressing dopamine D1 receptor (D1R-MSNs), and the indirect pathway, expressing dopamine D2 receptor (D2R-MSNs). While molecular mechanisms of MSN degeneration have been identified in animal models of striatal damage, the molecular factors that dictate a selective vulnerability of D1R-MSNs or D2R-MSNs remain unknown. Here, we combined genetic, chemogenetic, and pharmacological strategies with behavioral and neurochemical analyses, and show that the pool of cannabinoid CB1 receptor (CB1R) located on corticostriatal terminals efficiently safeguards D1R-MSNs, but not D2R-MSNs, from different insults. This cell-specific response relies on the regulation of glutamatergic signaling, and is independent from the CB1R-dependent control of astroglial activity in the striatum. These findings define cortical CB1R as a pivotal synaptic player in dictating a differential vulnerability of D1R-MSNs versus D2R-MSNs, and increase our understanding of the role of coordinated cannabinergic-glutamatergic signaling in establishing corticostriatal circuits and its dysregulation in neurodegenerative diseases.
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Affiliation(s)
- Andrea Ruiz-Calvo
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Instituto Universitario de Investigación Neuroquímica (IUIN) and Department of Biochemistry and Molecular Biology I, Complutense University, 28040 Madrid, Spain.,Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), 28034 Madrid, Spain
| | - Irene B Maroto
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Instituto Universitario de Investigación Neuroquímica (IUIN) and Department of Biochemistry and Molecular Biology I, Complutense University, 28040 Madrid, Spain.,Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), 28034 Madrid, Spain
| | - Raquel Bajo-Grañeras
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Instituto Universitario de Investigación Neuroquímica (IUIN) and Department of Biochemistry and Molecular Biology I, Complutense University, 28040 Madrid, Spain.,Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), 28034 Madrid, Spain
| | - Anna Chiarlone
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Instituto Universitario de Investigación Neuroquímica (IUIN) and Department of Biochemistry and Molecular Biology I, Complutense University, 28040 Madrid, Spain.,Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), 28034 Madrid, Spain
| | - Ángel Gaudioso
- Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), 28034 Madrid, Spain
| | - José J Ferrero
- Instituto Universitario de Investigación Neuroquímica (IUIN) and Department of Biochemistry and Molecular Biology IV, Complutense University, 28040 Madrid, Spain
| | - Eva Resel
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Instituto Universitario de Investigación Neuroquímica (IUIN) and Department of Biochemistry and Molecular Biology I, Complutense University, 28040 Madrid, Spain.,Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), 28034 Madrid, Spain
| | - José Sánchez-Prieto
- Instituto Universitario de Investigación Neuroquímica (IUIN) and Department of Biochemistry and Molecular Biology IV, Complutense University, 28040 Madrid, Spain
| | | | - Giovanni Marsicano
- INSERM and University of Bordeaux, NeuroCentre Magendie, Physiopathologie de la Plasticité Neuronale, U1215, 33077 Bordeaux, France
| | - Ismael Galve-Roperh
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Instituto Universitario de Investigación Neuroquímica (IUIN) and Department of Biochemistry and Molecular Biology I, Complutense University, 28040 Madrid, Spain.,Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), 28034 Madrid, Spain
| | - Luigi Bellocchio
- INSERM and University of Bordeaux, NeuroCentre Magendie, Physiopathologie de la Plasticité Neuronale, U1215, 33077 Bordeaux, France
| | - Manuel Guzmán
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Instituto Universitario de Investigación Neuroquímica (IUIN) and Department of Biochemistry and Molecular Biology I, Complutense University, 28040 Madrid, Spain.,Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), 28034 Madrid, Spain
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Schmidt ME, Buren C, Mackay JP, Cheung D, Dal Cengio L, Raymond LA, Hayden MR. Altering cortical input unmasks synaptic phenotypes in the YAC128 cortico-striatal co-culture model of Huntington disease. BMC Biol 2018; 16:58. [PMID: 29945611 PMCID: PMC6020351 DOI: 10.1186/s12915-018-0526-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Accepted: 05/08/2018] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Huntington disease (HD) is a fatal neurodegenerative disorder caused by a CAG expansion in the huntingtin (HTT) gene, leading to selective and progressive neuronal death predominantly in the striatum. Mutant HTT expression causes dysfunctional cortico-striatal (CS) transmission, loss of CS synapses, and striatal medium spiny neuron (MSN) dendritic spine instability prior to neuronal death. Co-culturing cortical and striatal neurons in vitro promotes the formation of functional CS synapses and is a widely used approach to elucidate pathogenic mechanisms of HD and to validate potential synapto-protective therapies. A number of relevant in vivo synaptic phenotypes from the YAC128 HD mouse model, which expresses full-length transgenic human mutant HTT, are recapitulated in CS co-culture by 21 days in vitro (DIV). However, striatal spine loss, which occurs in HD patients and in vivo animal models, has been observed in YAC128 CS co-culture in some studies but not in others, leading to difficulties in reproducing and interpreting results. Here, we investigated whether differences in the relative proportion of cortical and striatal neurons alter YAC128 synaptic phenotypes in this model. RESULTS YAC128 MSNs in 1:1 CS co-culture exhibited impaired dendritic length and complexity compared to wild-type, whereas reducing cortical input using a 1:3 CS ratio revealed a dramatic loss of YAC128 MSN dendritic spines. Chimeric experiments determined that this spine instability was primarily cell autonomous, depending largely on mutant HTT expression in striatal neurons. Moreover, we found that spontaneous electrophysiological MSN activity correlated closely with overall dendritic length, with no differences observed between genotypes in 1:3 co-cultures despite significant YAC128 spine loss. Finally, limiting cortical input with a 1:3 CS ratio impaired the basal survival of YAC128 neurons at DIV21, and this was partially selective for dopamine- and cAMP-regulated phosphoprotein 32-positive MSNs. CONCLUSIONS Our findings reconcile previous discordant reports of spine loss in this model, and improve the utility and reliability of the CS co-culture for the development of novel therapeutic strategies for HD.
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Affiliation(s)
- Mandi E Schmidt
- Centre for Molecular Medicine and Therapeutics, BC Children's Hospital Research Institute, University of British Columbia, 950 West 28th Avenue, Vancouver, V5Z 4H4, Canada
| | - Caodu Buren
- Department of Psychiatry and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 4834-2255 Wesbrook Mall, Vancouver, V6T 1Z3, Canada.,Present address: The Hospital for Sick Children, 555 University Avenue, Toronto, M5G 1X8, Canada
| | - James P Mackay
- Department of Psychiatry and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 4834-2255 Wesbrook Mall, Vancouver, V6T 1Z3, Canada
| | - Daphne Cheung
- Centre for Molecular Medicine and Therapeutics, BC Children's Hospital Research Institute, University of British Columbia, 950 West 28th Avenue, Vancouver, V5Z 4H4, Canada
| | - Louisa Dal Cengio
- Centre for Molecular Medicine and Therapeutics, BC Children's Hospital Research Institute, University of British Columbia, 950 West 28th Avenue, Vancouver, V5Z 4H4, Canada
| | - Lynn A Raymond
- Department of Psychiatry and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, 4834-2255 Wesbrook Mall, Vancouver, V6T 1Z3, Canada
| | - Michael R Hayden
- Centre for Molecular Medicine and Therapeutics, BC Children's Hospital Research Institute, University of British Columbia, 950 West 28th Avenue, Vancouver, V5Z 4H4, Canada.
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Rebec GV. Corticostriatal network dysfunction in Huntington's disease: Deficits in neural processing, glutamate transport, and ascorbate release. CNS Neurosci Ther 2018; 24:281-291. [PMID: 29464896 PMCID: PMC6489880 DOI: 10.1111/cns.12828] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 01/10/2018] [Accepted: 01/27/2018] [Indexed: 12/25/2022] Open
Abstract
AIMS This review summarizes evidence for dysfunctional connectivity between cortical and striatal neurons in Huntington's disease (HD), a fatal neurodegenerative condition caused by a single gene mutation. The focus is on data derived from recording of electrophysiological signals in behaving transgenic mouse models. DISCUSSIONS Firing patterns of individual neurons and the frequency oscillations of local field potentials indicate a disruption in corticostriatal processing driven, in large part, by interactions between cells that contain the mutant gene rather than the mutant gene alone. Dysregulation of glutamate, an excitatory amino acid released by cortical afferents, plays a key role in the breakdown of corticostriatal communication, a process modulated by ascorbate, an antioxidant vitamin found in high concentration in striatum. Up-regulation of glutamate transport by drug administration or viral-vector delivery improves ascorbate homeostasis and neurobehavioral processing in HD mice. Further analysis of electrophysiological data, including the use of sophisticated computational strategies, is required to discern how behavioral demands modulate the flow of corticostriatal information and its disruption by HD. CONCLUSIONS Long before massive cell loss occurs, HD impairs the mechanisms by which cortical and striatal neurons communicate. A key problem identified in transgenic animal models is dysregulation of the dynamic changes in extracellular glutamate and ascorbate. Improved understanding of how these neurochemical systems impact corticostriatal communication is necessary before an effective therapeutic strategy can emerge.
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Affiliation(s)
- George V. Rebec
- Program in NeuroscienceDepartment of Psychological and Brain SciencesIndiana UniversityBloomingtonINUSA
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van Roon-Mom WMC, Roos RAC, de Bot ST. Dose-Dependent Lowering of Mutant Huntingtin Using Antisense Oligonucleotides in Huntington Disease Patients. Nucleic Acid Ther 2018; 28:59-62. [PMID: 29620999 DOI: 10.1089/nat.2018.0720] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
On December 11 of 2017, Ionis Pharmaceuticals published a press release announcing dose-dependent reductions of mutant huntingtin protein in their HTTRx Phase 1/2a study in Huntington disease (HD) patients. The results from this Ionis trial have gained much attention from the patient community and the oligonucleotide therapeutics field, since it is the first trial targeting the cause of HD, namely the mutant huntingtin protein, using antisense oligonucleotides (ASOs). The press release also states that the primary endpoints of the study (safety and tolerability) were met, but does not contain data. This news follows the approval of another therapeutic ASO nusinersen (trade name Spinraza) for a neurological disease, spinal muscular atrophy, by the U.S. Food and Drug Administration and European Medicines Agency, in 2016 and 2017, respectively. Combined, this offers hope for the development of the HTTRx therapy for HD patients.
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Affiliation(s)
| | - Raymund A C Roos
- 2 Department of Neurology, Leiden University Medical Center , Leiden, the Netherlands
| | - Susanne T de Bot
- 2 Department of Neurology, Leiden University Medical Center , Leiden, the Netherlands
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36
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Puigdellívol M, Saavedra A, Pérez-Navarro E. Cognitive dysfunction in Huntington's disease: mechanisms and therapeutic strategies beyond BDNF. Brain Pathol 2018; 26:752-771. [PMID: 27529673 DOI: 10.1111/bpa.12432] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 07/08/2016] [Indexed: 12/15/2022] Open
Abstract
One of the main focuses in Huntington's disease (HD) research, as well as in most neurodegenerative diseases, is the development of new therapeutic strategies, as currently there is no treatment to delay or prevent the progression of the disease. Neuronal dysfunction and neuronal death in HD are caused by a combination of interrelated pathogenic processes that lead to motor, cognitive and psychiatric symptoms. Understanding how mutant huntingtin impacts on a plethora of cellular functions could help to identify new molecular targets. Although HD has been classically classified as a neurodegenerative disease affecting voluntary movement, lately cognitive dysfunction is receiving increased attention as it is very invalidating for patients. Thus, an ambitious goal in HD research is to find altered molecular mechanisms that contribute to cognitive decline. In this review, we have focused on those findings related to corticostriatal and hippocampal cognitive dysfunction in HD, as well as on the underlying molecular mechanisms, which constitute potential therapeutic targets. These include alterations in synaptic plasticity, transcriptional machinery and neurotrophic and neurotransmitter signaling.
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Affiliation(s)
- Mar Puigdellívol
- Departament de Biomedicina, Facultat de Medicina, Universitat de Barcelona, Barcelona, Catalonia, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Catalonia, Spain.,Centro de Investigación Biomédica en Red (CIBER) sobre Enfermedades Neurodegenerativas (CIBERNED), Spain
| | - Ana Saavedra
- Departament de Biomedicina, Facultat de Medicina, Universitat de Barcelona, Barcelona, Catalonia, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Catalonia, Spain.,Centro de Investigación Biomédica en Red (CIBER) sobre Enfermedades Neurodegenerativas (CIBERNED), Spain.,Institut de Neurociències, Universitat de Barcelona, Catalonia, Spain
| | - Esther Pérez-Navarro
- Departament de Biomedicina, Facultat de Medicina, Universitat de Barcelona, Barcelona, Catalonia, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Catalonia, Spain.,Centro de Investigación Biomédica en Red (CIBER) sobre Enfermedades Neurodegenerativas (CIBERNED), Spain.,Institut de Neurociències, Universitat de Barcelona, Catalonia, Spain
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37
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Virlogeux A, Moutaux E, Christaller W, Genoux A, Bruyère J, Fino E, Charlot B, Cazorla M, Saudou F. Reconstituting Corticostriatal Network on-a-Chip Reveals the Contribution of the Presynaptic Compartment to Huntington’s Disease. Cell Rep 2018; 22:110-122. [DOI: 10.1016/j.celrep.2017.12.013] [Citation(s) in RCA: 91] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Revised: 11/01/2017] [Accepted: 12/01/2017] [Indexed: 10/18/2022] Open
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Veldman MB, Yang XW. Molecular insights into cortico-striatal miscommunications in Huntington's disease. Curr Opin Neurobiol 2017; 48:79-89. [PMID: 29125980 DOI: 10.1016/j.conb.2017.10.019] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Accepted: 10/18/2017] [Indexed: 12/12/2022]
Abstract
Huntington's disease (HD), a dominantly inherited neurodegenerative disease, is defined by its genetic cause, a CAG-repeat expansion in the HTT gene, its motor and psychiatric symptomology and primary loss of striatal medium spiny neurons (MSNs). However, the molecular mechanisms from genetic lesion to disease phenotype remain largely unclear. Mouse models of HD have been created that exhibit phenotypes partially recapitulating those in the patient, and specifically, cortico-striatal disconnectivity appears to be a shared pathogenic event shared by HD mouse models and patients. Molecular studies have begun to unveil converging molecular and cellular pathogenic mechanisms that may account for cortico-striatal miscommunication in various HD mouse models. Systems biological approaches help to illuminate synaptic molecular networks as a nexus for HD cortio-striatal pathogenesis, and may offer new candidate targets to modify the disease.
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Affiliation(s)
- Matthew B Veldman
- Center for Neurobehavioral Genetics and Semel Institute for Neuroscience & Human Behavior, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, United States; Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, United States
| | - X William Yang
- Center for Neurobehavioral Genetics and Semel Institute for Neuroscience & Human Behavior, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, United States; Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, United States.
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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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40
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Asif-Malik A, Dautan D, Young AMJ, Gerdjikov TV. Altered cortico-striatal crosstalk underlies object recognition memory deficits in the sub-chronic phencyclidine model of schizophrenia. Brain Struct Funct 2017; 222:3179-3190. [PMID: 28293729 PMCID: PMC5585296 DOI: 10.1007/s00429-017-1393-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 02/22/2017] [Indexed: 11/29/2022]
Abstract
The neural mechanisms underlying cognitive deficits in schizophrenia are poorly understood. Sub-chronic treatment with the NMDA antagonist phencyclidine (PCP) produces cognitive abnormalities in rodents that reliably model aspects of the neurocognitive alterations observed in schizophrenia. Given that network activity across regions encompassing medial prefrontal cortex (mPFC) and nucleus accumbens (NAc) plays a significant role in motivational and cognitive tasks, we measured activity across cortico-striatal pathways in PCP-treated rats to characterize neural enabling and encoding of task performance in a novel object recognition task. We found that PCP treatment impaired task performance and concurrently (1) reduced tonic NAc neuronal activity, (2) desynchronized cross-activation of mPFC and NAc neurons, and (3) prevented the increase in mPFC and NAc neural activity associated with the exploration of a novel object in relation to a familiar object. Taken together, these observations reveal key neuronal and network-level adaptations underlying PCP-induced cognitive deficits, which may contribute to the emergence of cognitive abnormalities in schizophrenia.
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Affiliation(s)
- Aman Asif-Malik
- Department of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, LE1 9HN, UK
| | - Daniel Dautan
- Center for Molecular and Behavioral Neuroscience, Rutgers University, Newark, NJ, USA
| | - Andrew M J Young
- Department of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, LE1 9HN, UK
| | - Todor V Gerdjikov
- Department of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, LE1 9HN, UK.
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41
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Rangel-Barajas C, Estrada-Sánchez AM, Barton SJ, Luedtke RR, Rebec GV. Dysregulated corticostriatal activity in open-field behavior and the head-twitch response induced by the hallucinogen 2,5-dimethoxy-4-iodoamphetamine. Neuropharmacology 2016; 113:502-510. [PMID: 27816502 DOI: 10.1016/j.neuropharm.2016.11.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 09/19/2016] [Accepted: 11/01/2016] [Indexed: 10/20/2022]
Abstract
The substituted amphetamine, 2,5-dimethoxy-4-iodoamphetamine (DOI), is a hallucinogen that has been used to model a variety of psychiatric conditions. Here, we studied the effect of DOI on neural activity recorded simultaneously in the primary motor cortex (M1) and dorsal striatum of freely behaving FvB/N mice. DOI significantly decreased the firing rate of individually isolated neurons in M1 and dorsal striatum relative to pre-drug baseline. It also induced a bursting pattern of activity by increasing both the number of spikes within a burst and burst duration. In addition, DOI increased coincident firing between simultaneously recorded neuron pairs within the striatum and between M1 and dorsal striatum. Local field potential (LFP) activity also increased in coherence between M1 and dorsal striatum after DOI in the low frequency gamma band (30-50 Hz), while corticostriatal coherence in delta, theta, alpha, and beta activity decreased. We also assessed corticostriatal LFP activity in relation to the DOI-induced head-twitch response (HTR), a readily identifiable behavior used to assess potential treatments for the conditions it models. The HTR was associated with increased delta and decreased theta power in both M1 and dorsal striatum. Together, our results suggest that DOI dysregulates corticostriatal communication and that the HTR is associated with this dysregulation.
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Affiliation(s)
- Claudia Rangel-Barajas
- Indiana University Bloomington, Department of Psychological and Brain Sciences, Program in Neuroscience, 1101 E. 10th St., Bloomington, IN 47405, USA
| | - Ana María Estrada-Sánchez
- Indiana University Bloomington, Department of Psychological and Brain Sciences, Program in Neuroscience, 1101 E. 10th St., Bloomington, IN 47405, USA; Intellectual and Developmental Disabilities Research Center, Semel Institute, Department of Psychiatry & Biobehavioral Sciences, David Geffen School of Medicine, University of California, Los Angeles, USA
| | - Scott J Barton
- Indiana University Bloomington, Department of Psychological and Brain Sciences, Program in Neuroscience, 1101 E. 10th St., Bloomington, IN 47405, USA
| | - Robert R Luedtke
- University of North Texas Health Science Center, The Department of Pharmacology and Neuroscience, 3500 Camp Bowie Boulevard, Fort Worth, TX 76107, USA
| | - George V Rebec
- Indiana University Bloomington, Department of Psychological and Brain Sciences, Program in Neuroscience, 1101 E. 10th St., Bloomington, IN 47405, USA.
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TRiC subunits enhance BDNF axonal transport and rescue striatal atrophy in Huntington's disease. Proc Natl Acad Sci U S A 2016; 113:E5655-64. [PMID: 27601642 DOI: 10.1073/pnas.1603020113] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Corticostriatal atrophy is a cardinal manifestation of Huntington's disease (HD). However, the mechanism(s) by which mutant huntingtin (mHTT) protein contributes to the degeneration of the corticostriatal circuit is not well understood. We recreated the corticostriatal circuit in microfluidic chambers, pairing cortical and striatal neurons from the BACHD model of HD and its WT control. There were reduced synaptic connectivity and atrophy of striatal neurons in cultures in which BACHD cortical and striatal neurons were paired. However, these changes were prevented if WT cortical neurons were paired with BACHD striatal neurons; synthesis and release of brain-derived neurotrophic factor (BDNF) from WT cortical axons were responsible. Consistent with these findings, there was a marked reduction in anterograde transport of BDNF in BACHD cortical neurons. Subunits of the cytosolic chaperonin T-complex 1 (TCP-1) ring complex (TRiC or CCT for chaperonin containing TCP-1) have been shown to reduce mHTT levels. Both CCT3 and the apical domain of CCT1 (ApiCCT1) decreased the level of mHTT in BACHD cortical neurons. In cortical axons, they normalized anterograde BDNF transport, restored retrograde BDNF transport, and normalized lysosomal transport. Importantly, treating BACHD cortical neurons with ApiCCT1 prevented BACHD striatal neuronal atrophy by enhancing release of BDNF that subsequently acts through tyrosine receptor kinase B (TrkB) receptor on striatal neurons. Our findings are evidence that TRiC reagent-mediated reductions in mHTT enhanced BDNF delivery to restore the trophic status of BACHD striatal neurons.
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Bunner KD, Rebec GV. Corticostriatal Dysfunction in Huntington's Disease: The Basics. Front Hum Neurosci 2016; 10:317. [PMID: 27445757 PMCID: PMC4924423 DOI: 10.3389/fnhum.2016.00317] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Accepted: 06/13/2016] [Indexed: 11/23/2022] Open
Abstract
The main input to the basal ganglia, the corticostriatal pathway, shows some of the earliest signs of neuropathology in Huntington’s disease (HD), an inherited neurodegenerative condition that typically strikes in mid-life with progressively deteriorating cognitive, emotional, and motor symptoms. Although an effective treatment remains elusive, research on transgenic animal models has implicated dysregulation of glutamate (Glu), the excitatory amino acid released by corticostriatal neurons, in HD onset. Abnormalities in the control of Glu transmission at the level of postsynaptic receptors and Glu transport proteins play a critical role in the loss of information flow through downstream circuits that set the stage for the HD behavioral phenotype. Parallel but less-well characterized changes in dopamine (DA), a key modulator of Glu activation, ensure further deficits in neuronal communication throughout the basal ganglia. Continued analysis of corticostriatal Glu transmission and its modulation by DA, including analysis at the neurobehavioral level in transgenic models, is likely to be an effective strategy in the pursuit of HD therapeutics.
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Affiliation(s)
- Kendra D Bunner
- Department of Psychological and Brain Sciences, Program in Neuroscience, Indiana University Bloomington, IN, USA
| | - George V Rebec
- Department of Psychological and Brain Sciences, Program in Neuroscience, Indiana University Bloomington, IN, USA
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