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Nicastro N, Nencha U, Burkhard PR, Garibotto V. Dopaminergic imaging in degenerative parkinsonisms, an established clinical diagnostic tool. J Neurochem 2023; 164:346-363. [PMID: 34935143 DOI: 10.1111/jnc.15561] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 12/10/2021] [Accepted: 12/13/2021] [Indexed: 11/29/2022]
Abstract
Parkinson's disease (PD) and other neurodegenerative parkinsonisms are characterised by loss of striatal dopaminergic neurons. Dopamine functional deficits can be measured in vivo using positron emission tomography (PET) and single-photon emission computed tomography (SPECT) ligands assessing either presynaptic (e.g. dopamine synthesis and storage, transporter density) or postsynaptic terminals (i.e. D2 receptors availability). Nuclear medicine imaging thus helps the clinician to separate degenerative forms of parkinsonism with other neurological conditions, e.g. essential tremor or drug-induced parkinsonism. With the present study, we aimed at summarizing the current evidence about dopaminergic molecular imaging in the diagnostic evaluation of PD, atypical parkinsonian syndromes and dementia with Lewy bodies (DLB), as well as its potential to distinguish these conditions and to estimate disease progression. In fact, PET/SPECT methods are clinically validated and have been increasingly integrated into diagnostic guidelines (e.g. for PD and DLB). In addition, there is novel evidence on the classification properties of extrastriatal signal. Finally, dopamine imaging has an outstanding potential to detect neurodegeneration at the premotor stage, including REM-sleep behavior disorder and olfactory loss. Therefore, inclusion of subjects at an early stage for clinical trials can largely benefit from a validated in vivo biomarker such as presynaptic dopamine pathways PET/SPECT assessment.
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Affiliation(s)
- Nicolas Nicastro
- Division of Neurorehabilitation, Department of Clinical Neurosciences, Geneva University Hospitals, Geneva, Switzerland.,Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Umberto Nencha
- Division of Neurology, Department of Clinical Neurosciences, Geneva University Hospitals, Geneva, Switzerland
| | - Pierre R Burkhard
- Faculty of Medicine, University of Geneva, Geneva, Switzerland.,Division of Neurology, Department of Clinical Neurosciences, Geneva University Hospitals, Geneva, Switzerland
| | - Valentina Garibotto
- Faculty of Medicine, University of Geneva, Geneva, Switzerland.,Division of Nuclear Medicine and Molecular Imaging, Diagnostic Department, Geneva University Hospitals, Geneva, Switzerland
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2
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Kilbourn MR. 11C- and 18F-Radiotracers for In Vivo Imaging of the Dopamine System: Past, Present and Future. Biomedicines 2021; 9:108. [PMID: 33499179 PMCID: PMC7912183 DOI: 10.3390/biomedicines9020108] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 01/17/2021] [Accepted: 01/19/2021] [Indexed: 12/17/2022] Open
Abstract
The applications of positron emission tomography (PET) imaging to study brain biochemistry, and in particular the aspects of dopamine neurotransmission, have grown significantly over the 40 years since the first successful in vivo imaging studies in humans. In vivo PET imaging of dopaminergic functions of the central nervous system (CNS) including dopamine synthesis, vesicular storage, synaptic release and receptor binding, and reuptake processes, are now routinely used for studies in neurology, psychiatry, drug abuse and addiction, and drug development. Underlying these advances in PET imaging has been the development of the unique radiotracers labeled with positron-emitting radionuclides such as carbon-11 and fluorine-18. This review focuses on a selection of the more accepted and utilized PET radiotracers currently available, with a look at their past, present and future.
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Affiliation(s)
- Michael R Kilbourn
- Department of Radiology, University of Michigan Medical School, Ann Arbor, MI 48105, USA
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3
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Becker G, Bahri MA, Michel A, Hustadt F, Garraux G, Luxen A, Lemaire C, Plenevaux A. Comparative assessment of 6-[ 18 F]fluoro-L-m-tyrosine and 6-[ 18 F]fluoro-L-dopa to evaluate dopaminergic presynaptic integrity in a Parkinson's disease rat model. J Neurochem 2017; 141:626-635. [PMID: 28294334 DOI: 10.1111/jnc.14016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 02/21/2017] [Accepted: 02/28/2017] [Indexed: 12/16/2022]
Abstract
Because of the progressive loss of nigro-striatal dopaminergic terminals in Parkinson's disease (PD), in vivo quantitative imaging of dopamine (DA) containing neurons in animal models of PD is of critical importance in the preclinical evaluation of highly awaited disease-modifying therapies. Among existing methods, the high sensitivity of positron emission tomography (PET) is attractive to achieve that goal. The aim of this study was to perform a quantitative comparison of brain images obtained in 6-hydroxydopamine (6-OHDA) lesioned rats using two dopaminergic PET radiotracers, namely [18 F]fluoro-3,4-dihydroxyphenyl-L-alanine ([18 F]FDOPA) and 6-[18 F]fluoro-L-m-tyrosine ([18 F]FMT). Because the imaging signal is theoretically less contaminated by metabolites, we hypothesized that the latter would show stronger relationship with behavioural and post-mortem measures of striatal dopaminergic deficiency. We used a within-subject design to measure striatal [18 F]FMT and [18 F]FDOPA uptake in eight partially lesioned, eight fully lesioned and ten sham-treated rats. Animals were pretreated with an L-aromatic amino acid decarboxylase inhibitor. A catechol-O-methyl transferase inhibitor was also given before [18 F]FDOPA PET. Quantitative estimates of striatal uptake were computed using conventional graphical Patlak method. Striatal dopaminergic deficiencies were measured with apomorphine-induced rotations and post-mortem striatal DA content. We observed a strong relationship between [18 F]FMT and [18 F]FDOPA estimates of decreased uptake in the denervated striatum using the tissue-derived uptake rate constant Kc . However, only [18 F]FMT Kc succeeded to discriminate between the partial and the full 6-OHDA lesion and correlated well with the post-mortem striatal DA content. This study indicates that the [18 F]FMT could be more sensitive, with respect of [18 F]FDOPA, to investigate DA terminals loss in 6-OHDA rats, and open the way to in vivo L-aromatic amino acid decarboxylase activity targeting in future investigations on progressive PD models.
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Affiliation(s)
| | | | - Anne Michel
- Neurosciences TA Biology, UCB Pharma, Braine L'Alleud, Belgium
| | - Fabian Hustadt
- Neurosciences TA Biology, UCB Pharma, Braine L'Alleud, Belgium
| | - Gaëtan Garraux
- GIGA - CRC In vivo Imaging, University of Liège, Liège, Belgium
| | - André Luxen
- GIGA - CRC In vivo Imaging, University of Liège, Liège, Belgium
| | | | - Alain Plenevaux
- GIGA - CRC In vivo Imaging, University of Liège, Liège, Belgium
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4
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Kanazawa M, Ohba H, Iwazaki A, Kakiuchi T, Tsukada H. Synthesis of 6-[11C]methyl-m-tyrosine ([11C]6MemTyr) for dopamine synthesis imaging in living brain using PET. Bioorg Med Chem 2015; 23:729-34. [DOI: 10.1016/j.bmc.2014.12.061] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Revised: 12/25/2014] [Accepted: 12/26/2014] [Indexed: 11/29/2022]
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5
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Li CT, Palotti M, Holden JE, Oh J, Okonkwo O, Christian BT, Bendlin BB, Buyan-Dent L, Harding SJ, Stone CK, DeJesus OT, Nickles RJ, Gallagher CL. A dual-tracer study of extrastriatal 6-[18F]fluoro-m-tyrosine and 6-[18F]-fluoro-L-dopa uptake in Parkinson's disease. Synapse 2014; 68:325-31. [PMID: 24710997 DOI: 10.1002/syn.21745] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Accepted: 04/03/2014] [Indexed: 11/08/2022]
Abstract
6-[(18)F]-Fluoro-L-dopa (FDOPA) has been widely used as a biomarker for catecholamine synthesis, storage, and metabolism--its intense uptake in the striatum, and fainter uptake in other brain regions, is correlated with the symptoms and pathophysiology of Parkinson's disease (PD). 6-[(18)F]fluoro-m-tyrosine (FMT), which also targets L-amino acid decarboxylase, has potential advantages over FDOPA as a radiotracer because it does not form catechol-O-methyltransferase (COMT) metabolites. The purpose of the present study was to compare the regional distribution of these radiotracers in the brains of PD patients. Fifteen Parkinson's patients were studied with FMT and FDOPA positron emission tomography (PET) as well as high-resolution structural magnetic resonance imaging (MRI). MRI's were automatically parcellated into neuroanatomical regions of interest (ROIs) in Freesurfer (http://surfer.nmr.mgh.harvard.edu); region-specific uptake rate constants (Kocc) were generated from coregistered PET using a Patlak graphical approach. The essential findings were as follows: (1) regional Kocc were highly correlated between the radiotracers and in agreement with a previous FDOPA studies that used different ROI selection techniques; (2) FMT Kocc were higher in extrastriatal regions of relatively large uptake such as amygdala, pallidum, brainstem, hippocampus, entorhinal cortex, and thalamus, whereas cortical Kocc were similar between radiotracers; (3) while subcortical uptake of both radiotracers was related to disease duration and severity, cortical uptake was not. These results suggest that FMT may have advantages for examining pathologic changes within allocortical loop structures, which may contribute to cognitive and emotional symptoms of PD.
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Affiliation(s)
- Clarence T Li
- William S. Middleton Veterans Hospital and Geriatric Research Education and Clinical Center, Madison, Wisconsin; Department of Neurology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
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6
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Mizrahi R, Suridjan I, Kenk M, George TP, Wilson A, Houle S, Rusjan P. Dopamine response to psychosocial stress in chronic cannabis users: a PET study with [11C]-+-PHNO. Neuropsychopharmacology 2013; 38:673-82. [PMID: 23212454 PMCID: PMC3572464 DOI: 10.1038/npp.2012.232] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
A number of addictions have been linked with decreased striatal dopamine (DA) receptor availability and DA release. Stress has a key role in cannabis craving, as well as in modulation of dopaminergic signaling. The present study aimed to assess DA release in response to a laboratory stress task with [(11)C]-(+)-PHNO positron emission tomography in cannabis users (CU). Thirteen healthy CU and 12 healthy volunteers (HV) were scanned during a sensorimotor control task (SMCT) and under a stress condition using the validated Montreal imaging stress task (MIST). The simplified reference tissue model (SRTM) was used to obtain binding potential (BP(ND)) in striatal subdivisions: limbic striatum (LST), associative striatum (AST), and sensorimotor striatum (SMST). Stress-induced DA release (indexed as a percentage of reduction in [(11)C]-(+)-PHNO BP (ND)) between CU and HV was tested with analysis of variance. SMCT BP(ND) was significantly higher in CU compared with HV in the AST (F=10.38, p=0.003), LST (F=4.95, p=0.036), SMST (F=4.33, p=0.048), and whole striatum (F=9.02, p=0.006). Percentage of displacement (change in BP(ND) between SMCT and MIST PET scans) was not significantly different across groups in any brain region, except in the GP (-5.03±14.6 in CU, compared with 6.15±12.1 in HV; F=4.39, p=0.049). Duration of cannabis use was significantly associated with stress-induced [(11)C]-(+)-PHNO displacement by endogenous DA in the LST (r=0.566, p=0.044), with no effect in any other brain region. In conclusion, despite an increase in striatal BP(ND) observed during the control task, chronic cannabis use is not associated with alterations in stress-induced DA release.
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Affiliation(s)
- Romina Mizrahi
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada.
| | - Ivonne Suridjan
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Miran Kenk
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Tony P George
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada,Department of Psychiatry, Division of Brain and Therapeutics, University of Toronto, Toronto, ON, Canada,Schizophrenia Program, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Alan Wilson
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada,Department of Psychiatry, Division of Brain and Therapeutics, University of Toronto, Toronto, ON, Canada
| | - Sylvain Houle
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada,Department of Psychiatry, Division of Brain and Therapeutics, University of Toronto, Toronto, ON, Canada
| | - Pablo Rusjan
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada
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7
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The Assay of Enzyme Activity by Positron Emission Tomography. MOLECULAR IMAGING IN THE CLINICAL NEUROSCIENCES 2012. [DOI: 10.1007/7657_2012_53] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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8
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Gallagher CL, Christian BT, Holden JE, Dejesus OT, Nickles RJ, Buyan-Dent L, Bendlin BB, Harding SJ, Stone CK, Mueller B, Johnson SC. A within-subject comparison of 6-[18F]fluoro-m-tyrosine and 6-[18F]fluoro-L-dopa in Parkinson's disease. Mov Disord 2011; 26:2032-8. [PMID: 21638324 DOI: 10.1002/mds.23778] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2011] [Revised: 03/10/2011] [Accepted: 04/11/2011] [Indexed: 11/12/2022] Open
Abstract
Progression of Parkinson's disease symptoms is imperfectly correlated with positron emission tomography biomarkers for dopamine biosynthetic pathways. The radiopharmaceutical 6-[(18) F]fluoro-m-tyrosine is not a substrate for catechol-O-methyltransferase and therefore has a more favorable uptake-to-background ratio than 6-[(18) F]fluoro-L-dopa. The objective of this study was to evaluate 6-[(18) F]fluoro-m-tyrosine relative to 6-[(18) F]fluoro-L-dopa with partial catechol-O-methyltransferase inhibition as a biomarker for clinical status in Parkinson's disease. Twelve patients with early-stage Parkinson's disease, off medication, underwent Unified Parkinson Disease Rating Scale scoring, brain magnetic resonance imaging, and 3-dimensional dynamic positron emission tomography using equivalent doses of 6-[(18) F]fluoro-m-tyrosine and 6-[(18) F]fluoro-L-dopa with tolcapone, a catechol-O-methyltransferase inhibitor. Images were realigned within subject, after which the tissue-derived uptake rate constant was generated for volumes of interest encompassing the caudate nucleus, putamen, and subregions of the putamen. We computed both bivariate (Pearson) and partial (covariate of age) correlations between clinical subscores and tissue-derived uptake rate constant. Tissue-derived uptake rate constant values were correlated between the radiopharmaceuticals (r = 0.8). Motor subscores were inversely correlated with the contralateral putamen 6-[(18) F]fluoro-m-tyrosine tissue-derived uptake rate constant (|r| > 0.72, P < .005) but not significantly with the 6-[(18) F]fluoro-L-dopa tissue-derived uptake rate constant. The uptake rate constants for both radiopharmaceuticals were also inversely correlated with activities of daily living subscores, but the magnitude of correlation coefficients was greater for 6-[(18) F]fluoro-m-tyrosine. In this design, 6-[(18) F]fluoro-m-tyrosine uptake better reflected clinical status than did 6-[(18) F]fluoro-L-dopa uptake. We attribute this finding to 6-[(18) F]fluoro-m-tyrosine's higher affinity for the target, L-aromatic amino acid decarboxylase, and the absence of other major determinants of the uptake rate constant. These results also imply that L-aromatic amino acid decarboxylase activity is a major determinant of clinical status.
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9
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Braskie MN, Landau SM, Wilcox CE, Taylor SD, O'Neil JP, Baker SL, Madison CM, Jagust WJ. Correlations of striatal dopamine synthesis with default network deactivations during working memory in younger adults. Hum Brain Mapp 2010; 32:947-61. [PMID: 20578173 DOI: 10.1002/hbm.21081] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2009] [Revised: 01/11/2010] [Accepted: 03/25/2010] [Indexed: 11/08/2022] Open
Abstract
Age-related deficits have been demonstrated in working memory performance and in the dopamine system thought to support it. We performed positron emission tomography (PET) scans on 12 younger (mean 22.7 years) and 19 older (mean 65.8 years) adults using the radiotracer 6-[(18)F]-fluoro-L-m-tyrosine (FMT), which measures dopamine synthesis capacity. Subjects also underwent functional magnetic resonance imaging (fMRI) while performing a delayed recognition working memory task. We evaluated age-related fMRI activity differences and examined how they related to FMT signal variations in dorsal caudate within each age group. In posterior cingulate cortex and precuneus (PCC/Pc), older adults showed diminished fMRI deactivations during memory recognition compared with younger adults. Greater task-induced deactivation (in younger adults only) was associated both with higher FMT signal and with worse memory performance. Our results suggest that dopamine synthesis helps modulate default network activity in younger adults and that alterations to the dopamine system may contribute to age-related changes in working memory function.
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Affiliation(s)
- Meredith N Braskie
- Helen Wills Neuroscience Institute, University of California, Berkeley, California, USA
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10
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Kumakura Y, Cumming P. PET studies of cerebral levodopa metabolism: a review of clinical findings and modeling approaches. Neuroscientist 2010; 15:635-50. [PMID: 19793723 DOI: 10.1177/1073858409338217] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
[(18)F]Fluoro-3,4-dihydroxyphenyl-L-alanine (FDOPA) was one of the first successful tracers for molecular imaging by positron emission tomography (PET), and has proven immensely valuable for studies of Parkinson's disease. Following intravenous FDOPA injection, the decarboxylated metabolite [(18)F] fluorodopamine is formed and trapped within terminals of the nigrostriatal dopamine neurons; reduction in the simple ratio between striatum and cerebellum is indicative of nigrostriatal degeneration. However, the kinetic analysis of dynamic FDOPA-PET recordings is formidably complex due to the entry into brain of the plasma metabolite O-methyl-FDOPA and due to the eventual washout of decarboxylated metabolites. Linear graphical analysis relative to a reference tissue input function is popular and convenient for routine clinical studies in which serial arterial blood samples are unavailable. This simplified approach has facilitated longitudinal studies in large patient cohorts. Linear graphical analysis relative to the metabolite-corrected arterial FDOPA input yields a more physiological index of FDOPA utilization, the net blood-brain clearance. Using a constrained compartmental model, FDOPA-PET recordings can be used to calculate the relative activity of the enzyme DOPA decarboxylase in living brain. We have extended this approach so as to obtain an index of steady-state trapping of [( 18)F]fluorodopamine in synaptic vesicles. Although simple methods of image analysis are sufficient for the purposes of routine clinical studies, the more complex approaches have revealed hidden aspects of brain dopamine in personality, healthy aging, and in the pathophysiologies of Parkinson's disease and schizophrenia.
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Affiliation(s)
- Yoshitaka Kumakura
- Department of Nuclear Medicine, Graduate School of Medicine, University of Tokyo, and Research Center for Advanced Science and Technology, the University of Tokyo, Tokyo, Japan.
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Abstract
Past research has demonstrated that performance on frontal lobe-dependent tasks is associated with dopamine system integrity and that various dopamine system deficits occur with aging. The positron emission tomography (PET) radiotracer 6-[(18)F]fluoro-l-m-tyrosine (FMT) is a substrate of the dopamine-synthesizing enzyme, aromatic amino acid decarboxylase (AADC). Studies using 6-[(18)F]fluorodopa (FDOPA) (another AADC substrate) to measure how striatal PET signal and age relate have had inconsistent outcomes. The varying results occur in part from tracer processing that renders FDOPA signal subject to aspects of postrelease metabolism, which may themselves change with aging. In contrast, FMT remains a purer measure of AADC function. We used partial volume-corrected FMT PET scans to measure age-related striatal dopamine synthesis capacity in 21 older (mean, 66.9) and 16 younger (mean, 22.8) healthy adults. We also investigated how striatal FMT signal related to a cognitive measure of frontal lobe function. Older adults showed significantly greater striatal FMT signal than younger adults. Within the older group, FMT signal in dorsal caudate (DCA) and dorsal putamen was greater with age, suggesting compensation for deficits elsewhere in the dopamine system. In younger adults, FMT signal in DCA was lower with age, likely related to ongoing developmental processes. Younger adults who performed worse on tests of frontal lobe function showed greater FMT signal in right DCA, independent of age effects. Our data suggest that higher striatal FMT signal represents nonoptimal dopamine processing. They further support a relationship between striatal dopamine processing and frontal lobe cognitive function.
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Eberling JL, Bankiewicz KS, O'Neil JP, Jagust WJ. PET 6-[F]fluoro-L-m-tyrosine Studies of Dopaminergic Function in Human and Nonhuman Primates. Front Hum Neurosci 2008; 1:9. [PMID: 18958223 PMCID: PMC2525990 DOI: 10.3389/neuro.09.009.2007] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2007] [Accepted: 01/03/2008] [Indexed: 11/13/2022] Open
Abstract
Although positron emission tomography (PET) and the aromatic L-amino acid decarboxylase (AADC) tracer 6-[18F]fluoro-L-m-tyrosine (FMT) has been used to assess the integrity of the presynaptic dopamine system in the brain, relatively little has been published in terms of brain FMT uptake values especially for normal human subjects. Twelve normal volunteer subjects were scanned using PET and FMT to determine the range of normal striatal uptake values using Patlak graphical analysis. For comparison, seven adult rhesus monkeys were studied and the data analyzed in the same way. A subset of monkeys that were treated with a unilateral intracarotid artery infusion of the dopamine neurotoxin MPTP showed an 87% decrease in striatal FMT uptake. These findings support the use of PET and FMT to image AADC distribution in both normal and diseased brains using Patlak graphical analysis and tissue input functions.
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Affiliation(s)
- Jamie L. Eberling
- Department of Molecular Imaging and Neuroscience, Lawrence Berkeley National LaboratoryBerkeley, CA, USA
- Department of Neurology, University of CaliforniaDavis, CA, USA
- *Correspondence: Jamie L. Eberling, Department of Molecular Imaging and Neuroscience, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Mail Stop 55-121, Berkeley, CA 94720, USA; Department of Neurology, University of California, Davis, CA 95616, USA. e-mail:
| | | | - James P. O'Neil
- Department of Molecular Imaging and Neuroscience, Lawrence Berkeley National LaboratoryBerkeley, CA, USA
| | - William J. Jagust
- Department of Molecular Imaging and Neuroscience, Lawrence Berkeley National LaboratoryBerkeley, CA, USA
- Helen Wills Neuroscience Institute, University of CaliforniaBerkeley, CA, USA
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Vernaleken I, Kumakura Y, Cumming P, Buchholz HG, Siessmeier T, Stoeter P, Müller MJ, Bartenstein P, Gründer G. Modulation of [18F]fluorodopa (FDOPA) kinetics in the brain of healthy volunteers after acute haloperidol challenge. Neuroimage 2006; 30:1332-9. [PMID: 16439159 DOI: 10.1016/j.neuroimage.2005.11.014] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2005] [Revised: 11/03/2005] [Accepted: 11/09/2005] [Indexed: 11/23/2022] Open
Abstract
In animal studies, acute antipsychotic treatment was shown to enhance striatal DOPA-decarboxylase (DDC) activity. However, this phenomenon has not been demonstrated in humans by positron emission tomography (PET). Therefore, we investigated acute haloperidol effects on DDC activity in humans using [18F]fluorodopa (FDOPA) PET. Nine healthy volunteers were scanned with FDOPA in drug-free baseline conditions and after 3 days of haloperidol treatment (5 mg/day). A continuous performance test (CPT) was administered in both conditions. The net blood-brain clearance of FDOPA (K(in)app) in striatum, mesencephalon, and medial prefrontal cortex was calculated by volume-of-interest analysis. The macroparameter K(in)app is a composite of several kinetic terms defining the distribution volume of FDOPA in brain (V(e)D) and the relative activity of DOPA decarboxylase (k3D). Therefore, compartmental kinetic analysis was used to identify the physiological basis of the observed changes in K(in)app period. The magnitude of K(in)app was significantly increased in the putamen (18%) and mesencephalon (36%). Furthermore, V(e)D in the brain was increased by 15%. Increments of k3(D) in the basal ganglia did not attain statistical significance. The significant worsening of CPT results did not correlate with changes in FDOPA utilization. The present PET results indicate potentiation of FDOPA utilization in human basal ganglia by acute haloperidol treatment, apparently due to increased availability throughout the brain. The stimulation of DDC cannot be excluded due to insufficient statistical power in the estimation of k3(D) changes.
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Affiliation(s)
- Ingo Vernaleken
- Department of Psychiatry and Psychotherapy, RWTH Aachen University, Aachen, Germany.
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Mamo D, Remington G, Nobrega J, Hussey D, Chirakal R, Wilson AA, Baker G, Houle S, Kapur S. Effect of acute antipsychotic administration on dopamine synthesis in rodents and human subjects using 6-[18F]-L-m-tyrosine. Synapse 2004; 52:153-62. [PMID: 15034921 DOI: 10.1002/syn.20016] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Clinical effects of antipsychotic drugs are thought to be mediated primarily through antagonism of the dopamine D2 receptors. Recent studies have demonstrated increased aromatic decarboxylase activity following acute administration of dopamine D2 receptor antagonists both in vivo and ex vivo. However, this effect has never been demonstrated in human subjects. We studied the effect of acute antipsychotic administration on dopamine synthesis in rodents and healthy human subjects using 6-[18F]-L-m-tyrosine. In rats, we studied the effect of a single subcutaneous injection of haloperidol and risperidone on dopamine synthesis using 6-[18F]-L-m-tyrosine. In our human study, six healthy volunteers underwent two 6-[18F]-L-m-tyrosine PET scans, before and after 3 mg risperidone to measure the rate of accumulation of radioactivity in the striatum as an index of dopamine synthesis. The striatal/cerebellar radioactivity count ratio and the ratio of dopamine metabolites to dopamine concentration was significantly higher in all rodent treatment groups compared to controls. In the PET study we found no significant change in the rate of uptake in the striatum. Our results suggest that 6-[18F]-L-m-tyrosine PET may not be a useful tool in the study of the effect of antipsychotics on dopamine synthesis in human subjects.
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Affiliation(s)
- David Mamo
- Department of Psychiatry, University of Toronto, Canada.
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16
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Dejesus OT, Endres CJ, Shelton SE, Nickles RJ, Holden JE. Noninvasive assessment of aromatic L-amino acid decarboxylase activity in aging rhesus monkey brain in vivo. Synapse 2001; 39:58-63. [PMID: 11071710 DOI: 10.1002/1098-2396(20010101)39:1<58::aid-syn8>3.0.co;2-b] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The effect of aging on aromatic L-amino acid decarboxylase (AAAD) activity in rhesus monkey striatum was assessed in vivo using PET imaging. Two analogs of L-DOPA, 6-fluoro-m-tyrosine (FMT) and 6-fluoro-L-DOPA (FDOPA), were used to image rhesus monkeys of various ages. Results show that when the animals were grouped between young (3-11 years) and aged (25-37 years), FDOPA uptake in the older animals showed a 21% decline (P < 0.0005), while FMT uptake in young and older animals were not different. On the other hand, when individual uptake values were plotted vs. age, linear regression analysis showed FDOPA uptake similarly declined with age (r = -0.84, P < 0.001) while FMT uptake increased with age (r = 0.66, P < 0.05). Since FMT pharmacokinetics has been shown to be unaffected by metabolic steps occurring after the AAAD step, while FDOPA traces all the steps involved in L-DOPA metabolism, FMT is a suitable tracer to assess AAAD activity while FDOPA traces dopamine turnover. Based on these tracer characteristics, this study found that AAAD activity is maintained or increased in the aging rhesus monkey striatum while the FDOPA uptake decreases with age consistent with age-related declines in neuronal mechanisms whose overall effect is increased striatal dopamine turnover and clearance. Furthermore, comparison of results of this study with previous studies support the notion that the effect of aging in the dopamine system is different from that of MPTP-induced parkinsonism.
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Affiliation(s)
- O T Dejesus
- Department of Medical Physics, University of Wisconsin Medical School Madison, Wisconsin 53706, USA.
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Stein TD, DeJesus OT. Effect of 6-fluoro-m-tyrosine on dopamine release and metabolism in rat striatum using in vivo microdialysis. Brain Res 2000; 884:192-5. [PMID: 11082501 DOI: 10.1016/s0006-8993(00)02976-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
6-[(18)F]Fluoro-m-tyrosine (FMT) is a positron emission tomography (PET) imaging agent for the aromatic L-amino acid decarboxylase enzyme. Its parent compound, L-m-tyrosine (LMT) induces behavioral effects in rodents via dopamine release. To assess the potential pharmacologic effect of FMT, its role in dopamine release and metabolism in rat striatum was compared with LMT and L-DOPA using in vivo microdialysis. Results indicate that FMT will not have the same dopamine-induced behavioral effects as LMT.
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Affiliation(s)
- T D Stein
- Department of Medical Physics, University of Wisconsin Medical School, 1530 Medical Sciences Center, 1300 University Avenue, Madison, WI 53706, USA
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18
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Brown WD, DeJesus OT, Pyzalski RW, Malischke L, Roberts AD, Shelton SE, Uno H, Houser WD, Nickles RJ, Holden JE. Localization of trapping of 6-[(18)F]fluoro-L-m-tyrosine, an aromatic L-amino acid decarboxylase tracer for PET. Synapse 1999; 34:111-23. [PMID: 10502310 DOI: 10.1002/(sici)1098-2396(199911)34:2<111::aid-syn4>3.0.co;2-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The purpose of this study was to address four major questions regarding 6-FMT, a noncatecholic PET tracer for AAAD: 1) Where is the specific uptake of 6-FMT? 2) Why does it accumulate where and to the degree that it does? 3) How does its uptake differ from that of fluoroDOPA globally? and 4) Does its regional uptake differ significantly from that of fluoroDOPA? High-resolution PET scans were obtained in three rhesus monkeys using 6-FMT and in two of them using fluoroDOPA. Anatomic distribution was analyzed visually and quantitative uptake of 6-FMT was compared with published regional decarboxylase activity and monoamine neurotransmitter concentrations. In addition to high uptake in the dopamine-rich striatal nuclei, there was specific uptake of 6-FMT in brain regions which have little dopaminergic innervation but which have other amines in significant concentration. 6-FMT uptake correlated best with regional AAAD activity (r = 0.97). It correlated slightly less well with the sum of catecholamine and indolamine neurotransmitter concentrations, but does not correlate with dopamine concentration. The uptake of 6-FMT is greater than that of fluoroDOPA, with only slight differences in their regional distributions. Radiolabeled analogs of DOPA are often implicitly or explicitly regarded as tracers for presynaptic dopaminergic function. However, localization of these tracers more broadly includes many regions with relatively high concentrations of norepinephrine and serotonin. This may be especially important in diseases or experimental states in which dopaminergic neurons are selectively reduced, and may allow for the study of nondopaminergic neuronal systems in vivo with this tracer.
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Affiliation(s)
- W D Brown
- Department of Radiology, University of Wisconsin-Madison, USA.
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Doudet DJ, Chan GL, Jivan S, DeJesus OT, McGeer EG, English C, Ruth TJ, Holden JE. Evaluation of dopaminergic presynaptic integrity: 6-[18F]fluoro-L-dopa versus 6-[18F]fluoro-L-m-tyrosine. J Cereb Blood Flow Metab 1999; 19:278-87. [PMID: 10078880 DOI: 10.1097/00004647-199903000-00006] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The effectiveness of 6-[18F]fluoro-L-m-tyrosine (6FMT) to evaluate dopamine presynaptic integrity was compared to that of 6-[18F]fluoro-L-dopa (6FDOPA) in vivo by positron emission tomography (PET). Six normal and six 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned monkeys received 6FDOPA and 6FMT PET scans on separate occasions with identical scanning protocols. Four measures, the rate of uptake of tracer into striatum using either the arterial input function (Ki) or the activity in the occipital cortex as the input function (Kc), the rate of loss of striatal radioactivity (k(loss)), and an index of "effective turnover" of dopamine (k(loss)/Ki), were obtained for both tracers during extended PET studies. 6-[18F]Fluoro-L-m-tyrosine was as effective as 6FDOPA in separating normals from MPTP-lesioned subjects on the basis of the uptake rate constants Ki and Kc. However, in contrast to 6FDOPA, it was not possible to differentiate the normal from the lesioned animal using k(loss) or k(loss)/Ki for 6FMT. Thus, FMT appears to be a reasonable, highly specific tracer for studying the activity of aromatic dopa decarboxylase enzyme as an index of presynaptic integrity. However, if one is interested in investigating further the metabolic pathway and obtaining an in vivo estimate of the effective turnover of dopamine (after pharmacologic manipulation, for example), 6FDOPA remains the tracer of choice.
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Affiliation(s)
- D J Doudet
- Department of Medicine, University of British Columbia, Vancouver, Canada
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20
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Abstract
The trapping of decarboxylation products of radiolabelled dopa analogs in living human brain occurs as a function of the activity of dopa decarboxylase. This enzyme is now understood to regulate, with tyrosine hydroxylase, cerebral dopamine synthesis. Influx into brain of dopa decarboxylase substrates such as 6-[18F]fluorodopa and beta-[11C]dopa measured by positron emission tomography can be analyzed by solution of linear differential equations, assuming irreversible trapping of the decarboxylated products in brain. The isolation of specific physiological steps in the pathway for catecholamine synthesis requires compartmental modelling of the observed dynamic time-activity curves in plasma and in brain. The several approaches to the compartmental modelling of the kinetics of labelled substrates of dopa decarboxylase are now systematically and critically reviewed. Labelled catechols are extensively metabolized by hepatic catechol-O-methyltransferase yielding brain-penetrating metabolites. The assumption of a fixed blood-brain permeability ratio for O-methyl-6-[18F]fluorodopa or O-methyl-beta-[11C]dopa to the parent compounds eliminates several parameters from compartmental models. However, catechol-O-methyltransferase activity within brain remains a possible factor in underestimation of cerebral dopa decarboxylase activity. The O-methylation of labelled catechols is blocked with specific enzyme inhibitors, but dopa decarboxylase substrates derived from m-tyrosine may supplant the catechol tracers. The elimination from brain of decarboxylated tracer metabolites can be neglected without great prejudice to the estimation of dopa decarboxylase activity when tracer circulation is less than 60 minutes. However, elimination of dopamine metabolites from brain occurs at a rate close to that observed previously for metabolites of glucose labelled in the 6-position. This phenomenon can cause systematic underestimation of the rate of dopa decarboxylation in brain. The spillover of radioactivity due to the limited spatial resolution of tomographs also results in underestimation of dopa decarboxylase activity, but correction for partial volume effects is now possible. Estimates of dopa decarboxylase activity in human brain are increased several-fold by this correction. Abnormally low influx of dopa decarboxylase tracers in the basal ganglia is characteristic of Parkinson's disease and other movement disorders. Consistent with postmortem results, the impaired retention of labelled dopa is more pronounced in the putamen than in the caudate nucleus of patients with Parkinson's disease; this heterogeneity persists after correction for spillover. Current in vivo assays of dopa decarboxylase activity fail to discriminate clinically distinct stages in the progression of Parkinson's disease and are, by themselves, insufficient for differential diagnosis of Parkinson's disease and other subcortical movement disorders. However, potential new avenues for therapeutics can be tested by quantifying the rate of metabolism of exogenous dopa in living human brain.
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Affiliation(s)
- P Cumming
- McConnell Brain Imaging Centre, Montreal Neurological Institute, PQ Canada.
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Cumming P, Deep P, Rousset O, Evans A, Gjedde A. On the rate of decarboxylation of dopa to dopamine in living mammalian brain. Ann N Y Acad Sci 1997; 835:274-308. [PMID: 9616781 DOI: 10.1111/j.1749-6632.1997.tb48637.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- P Cumming
- McConnell Brain Imaging Centre, Montreal Neurological Institute, PQ, Canada
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