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Bidesi NSR, Vang Andersen I, Windhorst AD, Shalgunov V, Herth MM. The role of neuroimaging in Parkinson's disease. J Neurochem 2021; 159:660-689. [PMID: 34532856 PMCID: PMC9291628 DOI: 10.1111/jnc.15516] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 09/09/2021] [Accepted: 09/10/2021] [Indexed: 11/29/2022]
Abstract
Parkinson's disease (PD) is a neurodegenerative disorder that affects millions of people worldwide. Two hallmarks of PD are the accumulation of alpha-synuclein and the loss of dopaminergic neurons in the brain. There is no cure for PD, and all existing treatments focus on alleviating the symptoms. PD diagnosis is also based on the symptoms, such as abnormalities of movement, mood, and cognition observed in the patients. Molecular imaging methods such as magnetic resonance imaging (MRI), single-photon emission computed tomography (SPECT), and positron emission tomography (PET) can detect objective alterations in the neurochemical machinery of the brain and help diagnose and study neurodegenerative diseases. This review addresses the application of functional MRI, PET, and SPECT in PD patients. We provide an overview of the imaging targets, discuss the rationale behind target selection, the agents (tracers) with which the imaging can be performed, and the main findings regarding each target's state in PD. Molecular imaging has proven itself effective in supporting clinical diagnosis of PD and has helped reveal that PD is a heterogeneous disorder, which has important implications for the development of future therapies. However, the application of molecular imaging for early diagnosis of PD or for differentiation between PD and atypical parkinsonisms has remained challenging. The final section of the review is dedicated to new imaging targets with which one can detect the PD-related pathological changes upstream from dopaminergic degeneration. The foremost of those targets is alpha-synuclein. We discuss the progress of tracer development achieved so far and challenges on the path toward alpha-synuclein imaging in humans.
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Affiliation(s)
- Natasha S R Bidesi
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Ida Vang Andersen
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Albert D Windhorst
- Radiology and Nuclear Medicine, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam, Netherlands
| | - Vladimir Shalgunov
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Matthias M Herth
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark.,Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Copenhagen, Denmark
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2
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Lissemore JI, Nagano-Saito A, Smart K, Gravel P, Leyton M, Benkelfat C. Dopaminergic Plasticity in the Bilateral Hippocampus Following Threat Reversal in Humans. Sci Rep 2020; 10:7627. [PMID: 32376865 PMCID: PMC7203150 DOI: 10.1038/s41598-020-63977-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Accepted: 04/06/2020] [Indexed: 11/24/2022] Open
Abstract
When a cue no longer predicts a threat, a diminished ability to extinguish or reverse this association is thought to increase risk for stress-related disorders. Despite the clear clinical relevance, the mediating neurochemical mechanisms of threat reversal have received relatively little study. One neurotransmitter implicated in rodent research of changing associations with threat is dopamine. To study whether dopamine is involved in threat reversal in humans, we used high-resolution positron emission tomography (PET) coupled with 18F-fallypride. Twelve healthy volunteers (6 F/6 M) underwent three PET scans: (i) at baseline, (ii) following threat conditioning (the response to a cue associated with electric wrist shock), and (iii) following threat reversal (the response to the same cue now associated with safety). We observed moderate evidence of reduced dopamine D2/3 receptor availability, consistent with greater dopamine release, in the bilateral anterior hippocampus following threat reversal, in response to a safety cue that was previously associated with threat, as compared to both baseline and during exposure to the same cue prior to threat reversal. These findings offer the first preliminary evidence that the response to a previously threatening cue that has since become associated with safety involves dopaminergic neurotransmission within the hippocampus in healthy humans.
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Affiliation(s)
- Jennifer I Lissemore
- Department of Psychiatry, McGill University, 1033 Pine Avenue West, Montreal, H3A 1A1, Quebec, Canada.
| | - Atsuko Nagano-Saito
- Department of Psychiatry, McGill University, 1033 Pine Avenue West, Montreal, H3A 1A1, Quebec, Canada
| | - Kelly Smart
- Department of Psychiatry, McGill University, 1033 Pine Avenue West, Montreal, H3A 1A1, Quebec, Canada
| | - Paul Gravel
- Department of Psychiatry, McGill University, 1033 Pine Avenue West, Montreal, H3A 1A1, Quebec, Canada
- Department of Neurology and Neurosurgery, McConnell Brain Imaging Center, Montreal Neurological Institute, McGill University, 3801 University St., Montreal, H3A 2B4, Quebec, Canada
| | - Marco Leyton
- Department of Psychiatry, McGill University, 1033 Pine Avenue West, Montreal, H3A 1A1, Quebec, Canada
- Department of Neurology and Neurosurgery, McConnell Brain Imaging Center, Montreal Neurological Institute, McGill University, 3801 University St., Montreal, H3A 2B4, Quebec, Canada
| | - Chawki Benkelfat
- Department of Psychiatry, McGill University, 1033 Pine Avenue West, Montreal, H3A 1A1, Quebec, Canada
- Department of Neurology and Neurosurgery, McConnell Brain Imaging Center, Montreal Neurological Institute, McGill University, 3801 University St., Montreal, H3A 2B4, Quebec, Canada
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3
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Shalgunov V, van Waarde A, Booij J, Michel MC, Dierckx RAJO, Elsinga PH. Hunting for the high-affinity state of G-protein-coupled receptors with agonist tracers: Theoretical and practical considerations for positron emission tomography imaging. Med Res Rev 2018; 39:1014-1052. [PMID: 30450619 PMCID: PMC6587759 DOI: 10.1002/med.21552] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 10/02/2018] [Accepted: 10/19/2018] [Indexed: 12/15/2022]
Abstract
The concept of the high‐affinity state postulates that a certain subset of G‐protein‐coupled receptors is primarily responsible for receptor signaling in the living brain. Assessing the abundance of this subset is thus potentially highly relevant for studies concerning the responses of neurotransmission to pharmacological or physiological stimuli and the dysregulation of neurotransmission in neurological or psychiatric disorders. The high‐affinity state is preferentially recognized by agonists in vitro. For this reason, agonist tracers have been developed as tools for the noninvasive imaging of the high‐affinity state with positron emission tomography (PET). This review provides an overview of agonist tracers that have been developed for PET imaging of the brain, and the experimental paradigms that have been developed for the estimation of the relative abundance of receptors configured in the high‐affinity state. Agonist tracers appear to be more sensitive to endogenous neurotransmitter challenge than antagonists, as was originally expected. However, other expectations regarding agonist tracers have not been fulfilled. Potential reasons for difficulties in detecting the high‐affinity state in vivo are discussed.
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Affiliation(s)
- Vladimir Shalgunov
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Aren van Waarde
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Jan Booij
- Department of Radiology and Nuclear Medicine, Amsterdam University Medical Centers, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Martin C Michel
- Department of Pharmacology, Johannes Gutenberg University, Mainz, Germany
| | - Rudi A J O Dierckx
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.,Department of Nuclear Medicine, Ghent University, University Hospital, Ghent, Belgium
| | - Philip H Elsinga
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
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4
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Smart K, Cox SML, Nagano-Saito A, Rosa-Neto P, Leyton M, Benkelfat C. Test-retest variability of [ 11 C]ABP688 estimates of metabotropic glutamate receptor subtype 5 availability in humans. Synapse 2018; 72:e22041. [PMID: 29935121 DOI: 10.1002/syn.22041] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Revised: 06/01/2018] [Accepted: 06/06/2018] [Indexed: 12/12/2022]
Abstract
[11 C]ABP688 is a positron emission tomography (PET) radioligand that binds selectively to metabotropic glutamate type 5 receptors (mGluR5). The use of this tracer has identified receptor binding changes in clinical populations, and has been informative in drug occupancy studies. However, previous studies have found significant increases in [11 C]ABP688 binding in the later scan of same-day comparisons, and estimates of test-retest reliability under consistent scanning conditions are not available. The objective of this study was to assess the variability of [11 C]ABP688 binding in healthy people in scans performed at the same time of day. Two [11 C]ABP688 scans were acquired in eight healthy volunteers (6 women, 2 men) using a high-resolution research tomograph (HRRT). Scans were acquired 3 weeks apart with start times between 10:00am and 1:30pm. Mean mGluR5 binding potential (BPND ) values were calculated across cortical, striatal and limbic brain regions. Participants reported on subjective mood state after each scan and blood samples were drawn for cortisol analysis. No significant change in BPND between scans was observed. Variability in BPND values of 11-21% was observed across regions, with the greatest change in the hippocampus and amygdala. Reliability was low to moderate. BPND was not statistically related to scan start time, subjective anxiety, serum cortisol levels, or menstrual phase in women. Overall, [11 C]ABP688 BPND estimates show moderate variability in healthy people. Reliability is fair in cortical and striatal regions, and lower in limbic regions. Future research using this ligand should account for this in study design and analysis.
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Affiliation(s)
- Kelly Smart
- Department of Psychiatry, McGill University, 1033 Pine Ave W, Montreal, Quebec, H3A 1A1, Canada
| | - Sylvia M L Cox
- Department of Psychiatry, McGill University, 1033 Pine Ave W, Montreal, Quebec, H3A 1A1, Canada
| | - Atsuko Nagano-Saito
- Department of Psychiatry, McGill University, 1033 Pine Ave W, Montreal, Quebec, H3A 1A1, Canada
| | - Pedro Rosa-Neto
- Department of Neurology and Neurosurgery, McGill University, Montreal Neurological Institute, 3801 University Ave, Montreal, Quebec, H3A 2B4, Canada.,Translational Neuroimaging Laboratory, McGill University Research Centre for Studies in Aging, 6825 Boulevard LaSalle, Verdun, Quebec, H4H 1R3, Canada
| | - Marco Leyton
- Department of Psychiatry, McGill University, 1033 Pine Ave W, Montreal, Quebec, H3A 1A1, Canada.,Department of Neurology and Neurosurgery, McGill University, Montreal Neurological Institute, 3801 University Ave, Montreal, Quebec, H3A 2B4, Canada
| | - Chawki Benkelfat
- Department of Psychiatry, McGill University, 1033 Pine Ave W, Montreal, Quebec, H3A 1A1, Canada.,Department of Neurology and Neurosurgery, McGill University, Montreal Neurological Institute, 3801 University Ave, Montreal, Quebec, H3A 2B4, Canada
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Kanthan M, Cumming P, Hooker JM, Vasdev N. Classics in Neuroimaging: Imaging the Dopaminergic Pathway with PET. ACS Chem Neurosci 2017; 8:1817-1819. [PMID: 28719177 DOI: 10.1021/acschemneuro.7b00252] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The success of positron emission tomography (PET) for observing molecular processes underlying brain function and disease is underpinned by radiotracer chemistry. From the earliest applications of PET to measure dopamine synthesis capacity and the abundance of neuroreceptors and transporters, to the more recent topic of dynamic neurochemical imaging, interrogation of brain dopamine in conditions such as neurodegenerative diseases, schizophrenia, mood disorders, and addictions has been a driving force that challenges the ingenuity of radiopharmaceutical scientists. In fact, the pursuit of new ligands and reaction methods to address longstanding challenges has often been pioneered in the context of dopamine imaging. From this viewpoint, we highlight the unique history of imaging the dopaminergic pathway with PET, and present our interpretation of how this worldwide effort shaped and continues to drive the field of molecular imaging.
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Affiliation(s)
- Meghna Kanthan
- Division of Nuclear
Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114, United States
| | - Paul Cumming
- School of Psychology and Counselling and
IHBI, Queensland University of Technology, Brisbane, Queensland 4000, Australia
- QIMR Berghofer Medical Research Institute, Herston, Queensland 4006, Australia
| | - Jacob M. Hooker
- Athinoula A. Martinos Center for Biomedical
Imaging, Massachusetts General Hospital, Charlestown, Massachusetts 02129, United States
- Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Neil Vasdev
- Division of Nuclear
Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114, United States
- Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115, United States
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Caravaggio F, Kegeles LS, Wilson AA, Remington G, Borlido C, Mamo DC, Graff-Guerrero A. Estimating the effect of endogenous dopamine on baseline [(11) C]-(+)-PHNO binding in the human brain. Synapse 2016; 70:453-60. [PMID: 27341789 DOI: 10.1002/syn.21920] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 06/03/2016] [Accepted: 06/20/2016] [Indexed: 11/10/2022]
Abstract
Endogenous dopamine (DA) levels at dopamine D2/3 receptors (D2/3 R) have been quantified in the living human brain using the agonist radiotracer [(11) C]-(+)-PHNO. As an agonist radiotracer, [(11) C]-(+)-PHNO is more sensitive to endogenous DA levels than antagonist radiotracers. We sought to determine the proportion of the variance in baseline [(11) C]-(+)-PHNO binding to D2/3 Rs which can be accounted for by variation in endogenous DA levels. This was done by computing the Pearson's coefficient for the correlation between baseline binding potential (BPND ) and the change in BPND after acute DA depletion, using previously published data. All correlations were inverse, and the proportion of the variance in baseline [(11) C]-(+)-PHNO BPND that can be accounted for by variation in endogenous DA levels across the striatal subregions ranged from 42-59%. These results indicate that lower baseline values of [(11) C]-(+)-PHNO BPND reflect greater stimulation by endogenous DA. To further validate this interpretation, we sought to examine whether these data could be used to estimate the dissociation constant (Kd) of DA at D2/3 R. In line with previous in vitro work, we estimated the in vivo Kd of DA to be around 20 nM. In summary, the agonist radiotracer [(11) C]-(+)-PHNO can detect the impact of endogenous DA levels at D2/3 R in the living human brain from a single baseline scan, and may be more sensitive to this impact than other commonly employed radiotracers.
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Affiliation(s)
- Fernando Caravaggio
- Centre for Addiction and Mental Health, Research Imaging Centre, Toronto, Ontario, M5T 1R8, Canada.,Institute of Medical Science, University of Toronto, Toronto, Ontario, M5S 1A8, Canada
| | - Lawrence S Kegeles
- Department of Psychiatry and Radiology, Columbia University College of Physicians and Surgeons, New York State Psychiatric Institute, New York
| | - Alan A Wilson
- Centre for Addiction and Mental Health, Research Imaging Centre, Toronto, Ontario, M5T 1R8, Canada.,Institute of Medical Science, University of Toronto, Toronto, Ontario, M5S 1A8, Canada.,Department of Psychiatry, University of Toronto, Ontario, M5T 1R8, Canada
| | - Gary Remington
- Centre for Addiction and Mental Health, Research Imaging Centre, Toronto, Ontario, M5T 1R8, Canada.,Institute of Medical Science, University of Toronto, Toronto, Ontario, M5S 1A8, Canada.,Department of Psychiatry, University of Toronto, Ontario, M5T 1R8, Canada
| | - Carol Borlido
- Centre for Addiction and Mental Health, Research Imaging Centre, Toronto, Ontario, M5T 1R8, Canada
| | - David C Mamo
- Department of Psychiatry, Faculties of Medicine and Health Science, University of Malta, Msida, Malta
| | - Ariel Graff-Guerrero
- Centre for Addiction and Mental Health, Research Imaging Centre, Toronto, Ontario, M5T 1R8, Canada. .,Institute of Medical Science, University of Toronto, Toronto, Ontario, M5S 1A8, Canada. .,Department of Psychiatry, University of Toronto, Ontario, M5T 1R8, Canada.
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7
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de Witte WEA, Wong YC, Nederpelt I, Heitman LH, Danhof M, van der Graaf PH, Gilissen RAHJ, de Lange ECM. Mechanistic models enable the rational use of in vitro drug-target binding kinetics for better drug effects in patients. Expert Opin Drug Discov 2015; 11:45-63. [PMID: 26484747 DOI: 10.1517/17460441.2016.1100163] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION Drug-target binding kinetics are major determinants of the time course of drug action for several drugs, as clearly described for the irreversible binders omeprazole and aspirin. This supports the increasing interest to incorporate newly developed high-throughput assays for drug-target binding kinetics in drug discovery. A meaningful application of in vitro drug-target binding kinetics in drug discovery requires insight into the relation between in vivo drug effect and in vitro measured drug-target binding kinetics. AREAS COVERED In this review, the authors discuss both the relation between in vitro and in vivo measured binding kinetics and the relation between in vivo binding kinetics, target occupancy and effect profiles. EXPERT OPINION More scientific evidence is required for the rational selection and development of drug-candidates on the basis of in vitro estimates of drug-target binding kinetics. To elucidate the value of in vitro binding kinetics measurements, it is necessary to obtain information on system-specific properties which influence the kinetics of target occupancy and drug effect. Mathematical integration of this information enables the identification of drug-specific properties which lead to optimal target occupancy and drug effect in patients.
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Affiliation(s)
- Wilhelmus E A de Witte
- a Division of Pharmacology, Leiden Academic Centre for Drug Research , Leiden University , Einsteinweg 55, 2333 CC Leiden , The Netherlands
| | - Yin Cheong Wong
- a Division of Pharmacology, Leiden Academic Centre for Drug Research , Leiden University , Einsteinweg 55, 2333 CC Leiden , The Netherlands
| | - Indira Nederpelt
- b Division of Medicinal Chemistry, Leiden Academic Centre for Drug Research , Leiden University , Einsteinweg 55, 2333 CC Leiden , The Netherlands
| | - Laura H Heitman
- b Division of Medicinal Chemistry, Leiden Academic Centre for Drug Research , Leiden University , Einsteinweg 55, 2333 CC Leiden , The Netherlands
| | - Meindert Danhof
- a Division of Pharmacology, Leiden Academic Centre for Drug Research , Leiden University , Einsteinweg 55, 2333 CC Leiden , The Netherlands
| | - Piet H van der Graaf
- a Division of Pharmacology, Leiden Academic Centre for Drug Research , Leiden University , Einsteinweg 55, 2333 CC Leiden , The Netherlands
| | - Ron A H J Gilissen
- c A Division of Janssen Pharmaceutica N.V., Janssen Research and Development , Turnhoutseweg 30, Beerse 2340 , Belgium
| | - Elizabeth C M de Lange
- a Division of Pharmacology, Leiden Academic Centre for Drug Research , Leiden University , Einsteinweg 55, 2333 CC Leiden , The Netherlands
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Quelch D, De Santis V, Strege A, Myers J, Wells L, Nutt D, Lingford-Hughes A, Parker C, Tyacke R. Influence of agonist induced internalization on [3H]Ro15-4513 binding-an application to imaging fluctuations in endogenous GABA with positron emission tomography. Synapse 2014; 69:60-5. [DOI: 10.1002/syn.21780] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Revised: 08/12/2014] [Accepted: 08/27/2014] [Indexed: 02/05/2023]
Affiliation(s)
- Darren Quelch
- Centre for Neuropsychopharmacology; Division of Brain Sciences; Imperial College; London UK
| | | | | | - James Myers
- Centre for Neuropsychopharmacology; Division of Brain Sciences; Imperial College; London UK
| | - Lisa Wells
- Imanova Centro for Imaging Sciences; London UK
| | - David Nutt
- Centre for Neuropsychopharmacology; Division of Brain Sciences; Imperial College; London UK
| | - Anne Lingford-Hughes
- Centre for Neuropsychopharmacology; Division of Brain Sciences; Imperial College; London UK
| | | | - Robin Tyacke
- Centre for Neuropsychopharmacology; Division of Brain Sciences; Imperial College; London UK
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Shoup TM, McCauley JP, Lee DF, Chen R, Normandin MD, Bonab AA, El Fakhri G, Vasdev N. Synthesis of the dopamine D2/D3 receptor agonist (+)-PHNO via supercritical fluid chromatography: preliminary PET imaging study with [3-11C]-(+)PHNO. Tetrahedron Lett 2014. [DOI: 10.1016/j.tetlet.2013.11.113] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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10
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Berman BD, Hallett M, Herscovitch P, Simonyan K. Striatal dopaminergic dysfunction at rest and during task performance in writer's cramp. ACTA ACUST UNITED AC 2013; 136:3645-58. [PMID: 24148273 DOI: 10.1093/brain/awt282] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Writer's cramp is a task-specific focal hand dystonia characterized by involuntary excessive muscle contractions during writing. Although abnormal striatal dopamine receptor binding has been implicated in the pathophysiology of writer's cramp and other primary dystonias, endogenous dopamine release during task performance has not been previously investigated in writer's cramp. Using positron emission tomography imaging with the D2/D3 antagonist 11C-raclopride, we analysed striatal D2/D3 availability at rest and endogenous dopamine release during sequential finger tapping and speech production tasks in 15 patients with writer's cramp and 15 matched healthy control subjects. Compared with control subjects, patients had reduced 11C-raclopride binding to D2/D3 receptors at rest in the bilateral striatum, consistent with findings in previous studies. During the tapping task, patients had decreased dopamine release in the left striatum as assessed by reduced change in 11C-raclopride binding compared with control subjects. One cluster of reduced dopamine release in the left putamen during tapping overlapped with a region of reduced 11C-raclopride binding to D2/D3 receptors at rest. During the sentence production task, patients showed increased dopamine release in the left striatum. No overlap between altered dopamine release during speech production and reduced 11C-raclopride binding to D2/D3 receptors at rest was seen. Striatal regions where D2/D3 availability at rest positively correlated with disease duration were lateral and non-overlapping with striatal regions showing reduced D2/D3 receptor availability, except for a cluster in the left nucleus accumbens, which showed a negative correlation with disease duration and overlapped with striatal regions showing reduced D2/D3 availability. Our findings suggest that patients with writer's cramp may have divergent responses in striatal dopamine release during an asymptomatic motor task involving the dystonic hand and an unrelated asymptomatic task, sentence production. Our voxel-based results also suggest that writer's cramp may be associated with reduced striatal dopamine release occuring in the setting of reduced D2/D3 receptor availability and raise the possibility that basal ganglia circuits associated with premotor cortices and those associated with primary motor cortex are differentially affected in primary focal dystonias.
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Affiliation(s)
- Brian D Berman
- 1 Department of Neurology, University of Colorado Anschutz Medical Campus, Denver, CO USA
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