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Markova TZ, Ciampa CJ, Parent JH, LaPoint MR, D'Esposito M, Jagust WJ, Berry AS. Poorer aging trajectories are associated with elevated serotonin synthesis capacity. Mol Psychiatry 2023; 28:4390-4398. [PMID: 37460847 PMCID: PMC10792105 DOI: 10.1038/s41380-023-02177-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 06/28/2023] [Accepted: 06/30/2023] [Indexed: 01/18/2024]
Abstract
The dorsal raphe nucleus (DRN) is one of the earliest targets of Alzheimer's disease-related tau pathology and is a major source of brain serotonin. We used [18F]Fluoro-m-tyrosine ([18F]FMT) PET imaging to measure serotonin synthesis capacity in the DRN in 111 healthy adults (18-85 years-old). Similar to reports in catecholamine systems, we found elevated serotonin synthesis capacity in older adults relative to young. To establish the structural and functional context within which serotonin synthesis capacity is elevated in aging, we examined relationships among DRN [18F]FMT net tracer influx (Ki) and longitudinal changes in cortical thickness using magnetic resonance imaging, longitudinal changes in self-reported depression symptoms, and AD-related tau and β-amyloid (Aβ) pathology using cross-sectional [18F]Flortaucipir and [11C]Pittsburgh compound-B PET respectively. Together, our findings point to elevated DRN [18F]FMT Ki as a marker of poorer aging trajectories. Older adults with highest serotonin synthesis capacity showed greatest temporal lobe cortical atrophy. Cortical atrophy was associated with increasing depression symptoms over time, and these effects appeared to be strongest in individuals with highest serotonin synthesis capacity. We did not find direct relationships between serotonin synthesis capacity and AD-related pathology. Exploratory analyses revealed nuanced effects of sex within the older adult group. Older adult females showed the highest DRN synthesis capacity and exhibited the strongest relationships between entorhinal cortex tau pathology and increasing depression symptoms. Together these findings reveal PET measurement of the serotonin system to be a promising marker of aging trajectories relevant to both AD and affective changes in older age.
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Affiliation(s)
| | | | | | - Molly R LaPoint
- Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, CA, 94720, USA
| | - Mark D'Esposito
- Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, CA, 94720, USA
| | - William J Jagust
- Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, CA, 94720, USA
- Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
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2
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Chen HY, Parent JH, Ciampa CJ, Dahl MJ, Hämmerer D, Maass A, Winer JR, Yakupov R, Inglis B, Betts MJ, Berry AS. Interactive effects of locus coeruleus structure and catecholamine synthesis capacity on cognitive function. Front Aging Neurosci 2023; 15:1236335. [PMID: 37744395 PMCID: PMC10516288 DOI: 10.3389/fnagi.2023.1236335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Accepted: 08/24/2023] [Indexed: 09/26/2023] Open
Abstract
Background The locus coeruleus (LC) produces catecholamines (norepinephrine and dopamine) and is implicated in a broad range of cognitive functions including attention and executive function. Recent advancements in magnetic resonance imaging (MRI) approaches allow for the visualization and quantification of LC structure. Human research focused on the LC has since exploded given the LC's role in cognition and relevance to current models of psychopathology and neurodegenerative disease. However, it is unclear to what extent LC structure reflects underlying catecholamine function, and how LC structure and neurochemical function are collectively associated with cognitive performance. Methods A partial least squares correlation (PLSC) analysis was applied to 19 participants' LC structural MRI measures and catecholamine synthesis capacity measures assessed using [18F]Fluoro-m-tyrosine ([18F]FMT) positron emission tomography (PET). Results We found no direct association between LC-MRI and LC-[18F]FMT measures for rostral, middle, or caudal portions of the LC. We found significant associations between LC neuroimaging measures and neuropsychological performance that were driven by rostral and middle portions of the LC, which is in line with LC cortical projection patterns. Specifically, associations with executive function and processing speed arose from contributions of both LC structure and interactions between LC structure and catecholamine synthesis capacity. Conclusion These findings leave open the possibility that LC MRI and PET measures contribute unique information and suggest that their conjoint use may increase sensitivity to brain-behavior associations in small samples.
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Affiliation(s)
- Hsiang-Yu Chen
- Department of Psychology, Brandeis University, Waltham, MA, United States
| | - Jourdan H. Parent
- Department of Psychology, Brandeis University, Waltham, MA, United States
| | - Claire J. Ciampa
- Department of Psychology, Brandeis University, Waltham, MA, United States
| | - Martin J. Dahl
- Center for Lifespan Psychology, Max Planck Institute for Human Development, Berlin, Germany
- USC Leonard Davis School of Gerontology, University of Southern California, Los Angeles, CA, United States
| | - Dorothea Hämmerer
- Psychological Institute, University of Innsbruck, Innsbruck, Austria
| | - Anne Maass
- Deutsches Zentrum für Neurodegenerative Erkrankungen, Magdeburg, Germany
| | - Joseph R. Winer
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA, United States
| | - Renat Yakupov
- Deutsches Zentrum für Neurodegenerative Erkrankungen, Magdeburg, Germany
| | - Ben Inglis
- Henry H. Wheeler Jr. Brain Imaging Center, University of California, Berkeley, Berkeley, CA, United States
| | - Matthew J. Betts
- Deutsches Zentrum für Neurodegenerative Erkrankungen, Magdeburg, Germany
- Institute of Cognitive Neurology and Dementia Research, Otto-von-Guericke University Magdeburg, Magdeburg, Germany
- Center for Behavioral Brain Sciences, Otto-von-Guericke University Magdeburg, Magdeburg, Germany
| | - Anne S. Berry
- Department of Psychology, Brandeis University, Waltham, MA, United States
- Lawrence Berkeley National Laboratory, Berkeley, CA, United States
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van den Bosch R, Lambregts B, Määttä J, Hofmans L, Papadopetraki D, Westbrook A, Verkes RJ, Booij J, Cools R. Striatal dopamine dissociates methylphenidate effects on value-based versus surprise-based reversal learning. Nat Commun 2022; 13:4962. [PMID: 36002446 PMCID: PMC9402573 DOI: 10.1038/s41467-022-32679-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 08/10/2022] [Indexed: 11/13/2022] Open
Abstract
Psychostimulants such as methylphenidate are widely used for their cognitive enhancing effects, but there is large variability in the direction and extent of these effects. We tested the hypothesis that methylphenidate enhances or impairs reward/punishment-based reversal learning depending on baseline striatal dopamine levels and corticostriatal gating of reward/punishment-related representations in stimulus-specific sensory cortex. Young healthy adults (N = 100) were scanned with functional magnetic resonance imaging during a reward/punishment reversal learning task, after intake of methylphenidate or the selective D2/3-receptor antagonist sulpiride. Striatal dopamine synthesis capacity was indexed with [18F]DOPA positron emission tomography. Methylphenidate improved and sulpiride decreased overall accuracy and response speed. Both drugs boosted reward versus punishment learning signals to a greater degree in participants with higher dopamine synthesis capacity. By contrast, striatal and stimulus-specific sensory surprise signals were boosted in participants with lower dopamine synthesis. These results unravel the mechanisms by which methylphenidate gates both attention and reward learning. The mechanisms underpinning the variability in methylphenidate’s effects on cognition remain unclear. Here, the authors show that such effects reflect changes in striatal dopamine-related output gating of task-relevant cortical signals, and that these changes depend on baseline dopamine synthesis capacity.
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Affiliation(s)
- Ruben van den Bosch
- Radboud University, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands.
| | - Britt Lambregts
- Radboud University Medical Center, Department of Psychiatry, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands
| | - Jessica Määttä
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Lieke Hofmans
- Department of Developmental Psychology, University of Amsterdam, Amsterdam, The Netherlands
| | - Danae Papadopetraki
- Radboud University Medical Center, Department of Psychiatry, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands
| | - Andrew Westbrook
- Cognitive, Linguistic & Psychological Sciences Department, Brown University, Providence, RI, USA
| | - Robbert-Jan Verkes
- Radboud University Medical Center, Department of Psychiatry, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands
| | - Jan Booij
- Department of Radiology and Nuclear Medicine, Amsterdam University Medical Centers, location Academic Medical Center, Amsterdam, The Netherlands.,Radboud University Medical Center, Department of Medical Imaging, Nijmegen, The Netherlands
| | - Roshan Cools
- Radboud University Medical Center, Department of Psychiatry, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands
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4
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Hofmans L, Westbrook A, van den Bosch R, Booij J, Verkes RJ, Cools R. Effects of average reward rate on vigor as a function of individual variation in striatal dopamine. Psychopharmacology (Berl) 2022; 239:465-478. [PMID: 34735591 DOI: 10.1007/s00213-021-06017-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 10/15/2021] [Indexed: 11/24/2022]
Abstract
RATIONALE We constantly need to decide not only which actions to perform, but also how vigorously to perform them. In agreement with an earlier theoretical model, it has been shown that a significant portion of the variance in our action vigor can be explained by the average rate of rewards received for that action. Moreover, this invigorating effect of average reward rate was shown to vary with within-subject changes in dopamine, both in human individuals and experimental rodents. OBJECTIVES Here, we assessed whether individual differences in the effect of average reward rate on vigor are related to individual variation in a stable measure of striatal dopamine function in healthy, unmedicated participants. METHODS Forty-four participants performed a discrimination task to test the effect of average reward rate on response times to index vigor and completed an [18F]-DOPA PET scan to index striatal dopamine synthesis capacity. RESULTS We did not find an interaction between dopamine synthesis capacity and average reward rate across the entire group. However, a post hoc analysis revealed that participants with higher striatal dopamine synthesis capacity, particularly in the nucleus accumbens, exhibited a stronger invigorating effect of average reward rate among the 30 slowest participants. CONCLUSIONS Our findings provide converging evidence for a role of striatal dopamine in average reward rate signaling, thereby extending the current literature on the mechanistic link between average reward rate, vigor, and dopamine.
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Affiliation(s)
- Lieke Hofmans
- Donders Institute for Brain, Cognition & Behaviour, Radboud University, Nijmegen, The Netherlands. .,Department of Psychiatry, Radboudumc, Nijmegen, The Netherlands. .,Department of Psychology, University of Amsterdam, Amsterdam, The Netherlands.
| | - Andrew Westbrook
- Donders Institute for Brain, Cognition & Behaviour, Radboud University, Nijmegen, The Netherlands.,Department of Psychiatry, Radboudumc, Nijmegen, The Netherlands.,Department of Cognitive, Linguistics and Psychological Sciences, Brown University, Providence, USA
| | - Ruben van den Bosch
- Donders Institute for Brain, Cognition & Behaviour, Radboud University, Nijmegen, The Netherlands.,Department of Psychiatry, Radboudumc, Nijmegen, The Netherlands
| | - Jan Booij
- Department of Medical Imaging, Radboudumc, Nijmegen, The Netherlands.,Department of Radiology and Nuclear Medicine, Amsterdam University Medical Centers, location Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Robbert-Jan Verkes
- Department of Psychiatry, Radboudumc, Nijmegen, The Netherlands.,Forensic Psychiatric Centre Nijmegen, Pompestichting, Nijmegen, The Netherlands.,Department of Criminal Law, Law School, Radboud Universiteit, Nijmegen, The Netherlands
| | - Roshan Cools
- Donders Institute for Brain, Cognition & Behaviour, Radboud University, Nijmegen, The Netherlands.,Department of Psychiatry, Radboudumc, Nijmegen, The Netherlands
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Hofmans L, van den Bosch R, Määttä JI, Verkes RJ, Aarts E, Cools R. The cognitive effects of a promised bonus do not depend on dopamine synthesis capacity. Sci Rep 2020; 10:16473. [PMID: 33020514 PMCID: PMC7536197 DOI: 10.1038/s41598-020-72329-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 08/27/2020] [Indexed: 11/28/2022] Open
Abstract
Reward motivation is known to enhance cognitive control. However, detrimental effects have also been observed, which have been attributed to overdosing of already high baseline dopamine levels by further dopamine increases elicited by reward cues. Aarts et al. (2014) indeed demonstrated, in 14 individuals, that reward effects depended on striatal dopamine synthesis capacity, measured with [18F]FMT-PET: promised reward improved Stroop control in low-dopamine individuals, while impairing it in high-dopamine individuals. Here, we aimed to assess this same effect in 44 new participants, who had previously undergone an [18F]DOPA-PET scan to quantify dopamine synthesis capacity. This sample performed the exact same rewarded Stroop paradigm as in the prior study. However, we did not find any correlation between reward effects on cognitive control and striatal dopamine synthesis capacity. Critical differences between the radiotracers [18F]DOPA and [18F]FMT are discussed, as the discrepancy between the current and our previous findings might reflect the use of the potentially less sensitive [18F]DOPA radiotracer in the current study.
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Affiliation(s)
- Lieke Hofmans
- Donders Institute for Brain, Cognition and Behaviour, Radboud University, Kapittelweg 29 r.2.269, 6525 EN, Nijmegen, The Netherlands. .,Department of Psychiatry, Radboudumc, Nijmegen, The Netherlands.
| | - Ruben van den Bosch
- Donders Institute for Brain, Cognition and Behaviour, Radboud University, Kapittelweg 29 r.2.269, 6525 EN, Nijmegen, The Netherlands.,Department of Psychiatry, Radboudumc, Nijmegen, The Netherlands
| | - Jessica I Määttä
- Donders Institute for Brain, Cognition and Behaviour, Radboud University, Kapittelweg 29 r.2.269, 6525 EN, Nijmegen, The Netherlands.,Department of Psychiatry, Radboudumc, Nijmegen, The Netherlands
| | - Robbert-Jan Verkes
- Department of Psychiatry, Radboudumc, Nijmegen, The Netherlands.,Forensic Psychiatric Centre Nijmegen, Pompestichting, Nijmegen, The Netherlands.,Department of Criminal Law, Law School, Radboud Universiteit, Nijmegen, The Netherlands
| | - Esther Aarts
- Donders Institute for Brain, Cognition and Behaviour, Radboud University, Kapittelweg 29 r.2.269, 6525 EN, Nijmegen, The Netherlands
| | - Roshan Cools
- Donders Institute for Brain, Cognition and Behaviour, Radboud University, Kapittelweg 29 r.2.269, 6525 EN, Nijmegen, The Netherlands.,Department of Psychiatry, Radboudumc, Nijmegen, The Netherlands
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6
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Age-related variability in decision-making: Insights from neurochemistry. COGNITIVE AFFECTIVE & BEHAVIORAL NEUROSCIENCE 2020; 19:415-434. [PMID: 30536205 DOI: 10.3758/s13415-018-00678-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Despite dopamine's significant role in models of value-based decision-making and findings demonstrating loss of dopamine function in aging, evidence of systematic changes in decision-making over the life span remains elusive. Previous studies attempting to resolve the neural basis of age-related alteration in decision-making have typically focused on physical age, which can be a poor proxy for age-related effects on neural systems. There is growing appreciation that aging has heterogeneous effects on distinct components of the dopamine system within subject in addition to substantial variability between subjects. We propose that some of the conflicting findings in age-related effects on decision-making may be reconciled if we can observe the underlying dopamine components within individuals. This can be achieved by incorporating in vivo imaging techniques including positron emission tomography (PET) and neuromelanin-sensitive MR. Further, we discuss how affective factors may contribute to individual differences in decision-making performance among older adults. Specifically, we propose that age-related shifts in affective attention ("positivity effect") can, in some cases, counteract the impact of altered dopamine function on specific decision-making processes, contributing to variability in findings. In an effort to provide clarity to the field and advance productive hypothesis testing, we propose ways in which in vivo dopamine imaging can be leveraged to disambiguate dopaminergic influences on decision-making, and suggest strategies for assessing individual differences in the contribution of affective attentional focus.
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7
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Miyamoto M, Miyamoto T, Saitou J, Sato T. Longitudinal study of striatal aromatic l-amino acid decarboxylase activity in patients with idiopathic rapid eye movement sleep behavior disorder. Sleep Med 2020; 68:50-56. [PMID: 32028226 DOI: 10.1016/j.sleep.2019.09.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 09/15/2019] [Accepted: 09/20/2019] [Indexed: 12/20/2022]
Abstract
STUDY OBJECTIVES To determine if nigrostriatal dopaminergic system function, evaluated by aromatic l-amino acid decarboxylase (AADC) activity using 6-[18F]fluoro-meta-tyrosine brain positron emission tomography (FMT-PET) can accurately and efficiently identify idiopathic rapid-eye-movement behavior disorder (IRBD) individuals at risk for conversion to a clinical diagnosis of Parkinson's disease (PD) or dementia with Lewy bodies (DLB). METHODS We assessed prospectively striatal aromatic l-amino acid decarboxylase activity using FMT brain PET imaging in IRBD patients who were followed systematically every 1-3 months for 1-10 years. IRBD patients (n = 27) were enrolled in this prospective cohort study starting in 2009. Those who underwent follow-up scans between January 2011 and September 2014 (n = 24) were analyzed in the present study. RESULTS Of the 24 IRBD patients with baseline and follow-up FMT-PET scans, 11 (45.8%) developed PD (n = 6) or DLB (n = 5). Compared to IRBD patients who were still disease-free, those who developed PD (n = 5) or DLB with parkinsonism (n = 1) had significantly reduced bilateral putaminal FMT uptake during the follow-up. Furthermore, the rate of FMT decline between baseline and follow-up scans was higher in all converted patients, even for those with DLB without parkinsonism, than in IRBD patients who remained disease-free. CONCLUSIONS FMT-PET, which represents a dynamic change in AADC activity over time, may also be a useful predictor for the risk of conversion to PD or DLB over short-term clinical follow-up periods, or when testing neuroprotective and restorative strategies in the prodromal phases of PD or DLB.
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Affiliation(s)
- Masayuki Miyamoto
- Department of Neurology, Center of Sleep Medicine, Dokkyo Medical University, Japan
| | - Tomoyuki Miyamoto
- Department of Neurology, Dokkyo Medical University Saitama Medical Center, Japan.
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Berry AS, Shah VD, Jagust WJ. The Influence of Dopamine on Cognitive Flexibility Is Mediated by Functional Connectivity in Young but Not Older Adults. J Cogn Neurosci 2018; 30:1330-1344. [PMID: 29791298 DOI: 10.1162/jocn_a_01286] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Dopaminergic signaling in striatum is strongly implicated in executive functions including cognitive flexibility. However, there is a paucity of multimodal research in humans defining the nature of relationships between endogenous dopamine, striatal network activity, and cognition. Here, we measured dopamine synthesis capacity in young and older adults using the PET tracer 6-[18F]fluoro-l- m-tyrosine and examined its relationship with cognitive performance and functional connectivity during an fMRI study of task switching. Aging is associated with alteration in dopamine function, including profound losses in dopamine receptors but an apparent elevation in dopamine synthesis. A compensatory benefit of upregulated dopamine synthesis in aging has not been established. Across young and older adults, we found that cognitive flexibility (low behavioral switch cost) was associated with stronger task-related functional connectivity within canonical fronto-striato-thalamic circuits connecting left inferior frontal gyrus, dorsal caudate nucleus (DCA) and ventral lateral/ventral anterior thalamic nuclei. In young adults, functional connectivity mediated the influence of DCA dopamine synthesis capacity on switch cost. For older adults, these relationships were modified such that DCA synthesis capacity and connectivity interacted to influence switch cost. Older adults with most elevated synthesis capacity maintained the pattern of connectivity-cognition relationships observed in youth, whereas these relationships were not evident for older adults with low synthesis capacity. Together, these findings suggest a role of dopamine in tuning striatal circuits to benefit executive function in young adults and clarify the functional impact of elevated dopamine synthesis capacity in aging.
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Dopamine Synthesis Capacity is Associated with D2/3 Receptor Binding but Not Dopamine Release. Neuropsychopharmacology 2018; 43:1201-1211. [PMID: 28816243 PMCID: PMC5916345 DOI: 10.1038/npp.2017.180] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 08/07/2017] [Accepted: 08/10/2017] [Indexed: 01/08/2023]
Abstract
Positron Emission Tomography (PET) imaging allows the estimation of multiple aspects of dopamine function including dopamine synthesis capacity, dopamine release, and D2/3 receptor binding. Though dopaminergic dysregulation characterizes a number of neuropsychiatric disorders including schizophrenia and addiction, there has been relatively little investigation into the nature of relationships across dopamine markers within healthy individuals. Here we used PET imaging in 40 healthy adults to compare, within individuals, the estimates of dopamine synthesis capacity (Ki) using 6-[18F]fluoro-l-m-tyrosine ([18F]FMT; a substrate for aromatic amino acid decarboxylase), baseline D2/3 receptor-binding potential using [11C]raclopride (a weak competitive D2/3 receptor antagonist), and dopamine release using [11C]raclopride paired with oral methylphenidate administration. Methylphenidate increases synaptic dopamine by blocking the dopamine transporter. We estimated dopamine release by contrasting baseline D2/3 receptor binding and D2/3 receptor binding following methylphenidate. Analysis of relationships among the three measurements within striatal regions of interest revealed a positive correlation between [18F]FMT Ki and the baseline (placebo) [11C]raclopride measure, such that participants with greater synthesis capacity showed higher D2/3 receptor-binding potential. In contrast, there was no relationship between [18F]FMT and methylphenidate-induced [11C]raclopride displacement. These findings shed light on the nature of regulation between pre- and postsynaptic dopamine function in healthy adults, which may serve as a template from which to identify and describe alteration with disease.
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Neuro-Cognitive Effects of Acute Tyrosine Administration on Reactive and Proactive Response Inhibition in Healthy Older Adults. eNeuro 2018; 5:eN-NWR-0035-17. [PMID: 30094335 PMCID: PMC6084775 DOI: 10.1523/eneuro.0035-17.2018] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2017] [Revised: 03/01/2018] [Accepted: 03/24/2018] [Indexed: 01/02/2023] Open
Abstract
The aging brain is characterized by altered dopamine signaling. The amino acid tyrosine, a catecholamine precursor, is known to improve cognitive performance in young adults, especially during high environmental demands. Tyrosine administration might also affect catecholamine transmission in the aging brain, thereby improving cognitive functioning. In healthy older adults, impairments have been demonstrated in two forms of response inhibition: reactive inhibition (outright stopping) and proactive inhibition (anticipatory response slowing) under high information load. However, no study has directly compared the effects of a catecholamine precursor on reactive and load-dependent proactive inhibition. In this study we explored the effects of tyrosine on reactive and proactive response inhibition and signal in dopaminergically innervated fronto-striatal regions. Depending on age, tyrosine might lead to beneficial or detrimental neurocognitive effects. We aimed to address these hypotheses in 24 healthy older human adults (aged 61-72 years) using fMRI in a double blind, counterbalanced, placebo-controlled, within-subject design. Across the group, tyrosine did not alter reactive or proactive inhibition behaviorally but did increase fronto-parietal proactive inhibition-related activation. When taking age into account, tyrosine affected proactive inhibition both behaviorally and neurally. Specifically, increasing age was associated with a greater detrimental effect of tyrosine compared with placebo on proactive slowing. Moreover, with increasing age, tyrosine decreased fronto-striatal and parietal proactive signal, which correlated positively with tyrosine's effects on proactive slowing. Concluding, tyrosine negatively affected proactive response slowing and associated fronto-striatal activation in an age-dependent manner, highlighting the importance of catecholamines, perhaps particularly dopamine, for proactive response inhibition in older adults.
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11
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Aging Affects Dopaminergic Neural Mechanisms of Cognitive Flexibility. J Neurosci 2016; 36:12559-12569. [PMID: 27807030 DOI: 10.1523/jneurosci.0626-16.2016] [Citation(s) in RCA: 93] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 09/27/2016] [Accepted: 10/22/2016] [Indexed: 01/08/2023] Open
Abstract
Aging is accompanied by profound changes in the brain's dopamine system that affect cognitive function. Evidence of powerful individual differences in cognitive aging has sharpened focus on identifying biological factors underlying relative preservation versus vulnerability to decline. Dopamine represents a key target in these efforts. Alterations of dopamine receptors and dopamine synthesis are seen in aging, with receptors generally showing reduction and synthesis demonstrating increases. Using the PET tracer 6-[18F]fluoro-l-m-tyrosine, we found strong support for upregulated striatal dopamine synthesis capacity in healthy older adult humans free of amyloid pathology, relative to young people. We next used fMRI to define the functional impact of elevated synthesis capacity on cognitive flexibility, a core component of executive function. We found clear evidence in young adults that low levels of synthesis capacity were suboptimal, associated with diminished cognitive flexibility and altered frontoparietal activation relative to young adults with highest synthesis values. Critically, these relationships between dopamine, performance, and activation were transformed in older adults with higher synthesis capacity. Variability in synthesis capacity was related to intrinsic frontoparietal functional connectivity across groups, suggesting that striatal dopamine synthesis influences the tuning of networks underlying cognitive flexibility. Together, these findings define striatal dopamine's association with cognitive flexibility and its neural underpinnings in young adults, and reveal the alteration in dopamine-related neural processes in aging. SIGNIFICANCE STATEMENT Few studies have combined measurement of brain dopamine with examination of the neural basis of cognition in youth and aging to delineate the underlying mechanisms of these associations. Combining in vivo PET imaging of dopamine synthesis capacity, fMRI, and a sensitive measure of cognitive flexibility, we reveal three core findings. First, we find evidence supporting older adults' capacity to upregulate dopamine synthesis. Second, we define relationships between dopamine, cognition, and frontoparietal activity in young adults indicating high levels of synthesis capacity are optimal. Third, we demonstrate alteration of these relationships in older adults, suggesting neurochemical modulation of cognitive flexibility changes with age.
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12
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Preshlock S, Calderwood S, Verhoog S, Tredwell M, Huiban M, Hienzsch A, Gruber S, Wilson TC, Taylor NJ, Cailly T, Schedler M, Collier TL, Passchier J, Smits R, Mollitor J, Hoepping A, Mueller M, Genicot C, Mercier J, Gouverneur V. Enhanced copper-mediated (18)F-fluorination of aryl boronic esters provides eight radiotracers for PET applications. Chem Commun (Camb) 2016; 52:8361-4. [PMID: 27241832 DOI: 10.1039/c6cc03295h] [Citation(s) in RCA: 113] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
[(18)F]FMTEB, [(18)F]FPEB, [(18)F]flumazenil, [(18)F]DAA1106, [(18)F]MFBG, [(18)F]FDOPA, [(18)F]FMT and [(18)F]FDA are prepared from the corresponding arylboronic esters and [(18)F]KF/K222 in the presence of Cu(OTf)2py4. The method was successfully applied using three radiosynthetic platforms, and up to 26 GBq of non-carrier added starting activity of (18)F-fluoride.
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Affiliation(s)
- Sean Preshlock
- University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, OX1 3TA Oxford, UK.
| | - Samuel Calderwood
- University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, OX1 3TA Oxford, UK.
| | - Stefan Verhoog
- University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, OX1 3TA Oxford, UK.
| | - Matthew Tredwell
- University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, OX1 3TA Oxford, UK.
| | - Mickael Huiban
- Imanova, Burlington Danes building Imperial College, London Hammersmith Hospital, Du Cane Road, London W12 0NN, UK
| | - Antje Hienzsch
- ABX GmbH Heinrich-Glaeser-Strasse 10-14, D-01454 Radeberg, Germany
| | - Stefan Gruber
- University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, OX1 3TA Oxford, UK.
| | - Thomas C Wilson
- University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, OX1 3TA Oxford, UK.
| | - Nicholas J Taylor
- University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, OX1 3TA Oxford, UK.
| | - Thomas Cailly
- University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, OX1 3TA Oxford, UK. and Normandie University, UNICAEN, CERMN, F-14032 Caen, France
| | - Michael Schedler
- University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, OX1 3TA Oxford, UK.
| | | | - Jan Passchier
- Imanova, Burlington Danes building Imperial College, London Hammersmith Hospital, Du Cane Road, London W12 0NN, UK
| | - René Smits
- ABX GmbH Heinrich-Glaeser-Strasse 10-14, D-01454 Radeberg, Germany
| | - Jan Mollitor
- ABX GmbH Heinrich-Glaeser-Strasse 10-14, D-01454 Radeberg, Germany
| | | | - Marco Mueller
- ABX GmbH Heinrich-Glaeser-Strasse 10-14, D-01454 Radeberg, Germany
| | - Christophe Genicot
- Global Chemistry, UCB New Medicines, UCB Biopharma sprl, 1420 Braine-L'Alleud, Belgium
| | - Joël Mercier
- Global Chemistry, UCB New Medicines, UCB Biopharma sprl, 1420 Braine-L'Alleud, Belgium
| | - Véronique Gouverneur
- University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, OX1 3TA Oxford, UK.
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13
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Rotstein BH, Wang L, Liu RY, Patteson J, Kwan EE, Vasdev N, Liang SH. Mechanistic Studies and Radiofluorination of Structurally Diverse Pharmaceuticals with Spirocyclic Iodonium(III) Ylides. Chem Sci 2016; 7:4407-4417. [PMID: 27540460 PMCID: PMC4987086 DOI: 10.1039/c6sc00197a] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Theoretical studies provide insight into radiofluorination of non-activated electron-rich and sterically hindered 18F-arenes using a new class of adamantyl-based spirocyclic iodonium(iii) ylide precursors.
Synthesis of non-activated electron-rich and sterically hindered 18F-arenes remains a major challenge due to limitations of existing radiofluorination methodologies. Herein, we report on our mechanistic investigations of spirocyclic iodonium(iii) ylide precursors for arene radiofluorination, including their reactivity, selectivity, and stability with no-carrier-added [18F]fluoride. Benchmark calculations at the G2[ECP] level indicate that pseudorotation and reductive elimination at iodine(iii) can be modeled well by appropriately selected dispersion-corrected density functional methods. Modeling of the reaction pathways show that fluoride–iodonium(iii) adduct intermediates are strongly activated and highly regioselective for reductive elimination of the desired [18F]fluoroarenes (difference in barriers, ΔΔG‡ > 25 kcal mol–1). The advantage of spirocyclic auxiliaries is further supported by NMR spectroscopy studies, which bolster evidence for underlying decomposition processes which can be overcome for radiofluorination of iodonium(iii) precursors. Using a novel adamantyl auxiliary, sterically hindered iodonium ylides have been developed to enable highly efficient radiofluorination of electron-rich arenes, including fragments of pharmaceutically relevant nitrogen-containing heterocycles and tertiary amines. Furthermore, this methodology has been applied for the syntheses of the radiopharmaceuticals 6-[18F]fluoro-meta-tyrosine ([18F]FMT, 11 ± 1% isolated radiochemical yield, non-decay-corrected (RCY, n.d.c.), n = 3), and meta-[18F]fluorobenzylguanidine ([18F]mFBG, 14 ± 1% isolated RCY, n.d.c., n = 3) which cannot be directly radiolabeled using conventional nucleophilic aromatic substitution with [18F]fluoride.
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Affiliation(s)
- Benjamin H Rotstein
- Division of Nuclear Medicine and Molecular Imaging & Gordon Center for Medical Imaging, Massachusetts General Hospital, 55 Fruit Street, Boston, Massachusetts, 02114, United States of America; Department of Radiology, Harvard Medical School, 55 Fruit Street, Boston, Massachusetts, 02114, United States of America
| | - Lu Wang
- Division of Nuclear Medicine and Molecular Imaging & Gordon Center for Medical Imaging, Massachusetts General Hospital, 55 Fruit Street, Boston, Massachusetts, 02114, United States of America
| | - Richard Y Liu
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA, 02138, United States of America
| | - Jon Patteson
- Division of Nuclear Medicine and Molecular Imaging & Gordon Center for Medical Imaging, Massachusetts General Hospital, 55 Fruit Street, Boston, Massachusetts, 02114, United States of America
| | - Eugene E Kwan
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA, 02138, United States of America
| | - Neil Vasdev
- Division of Nuclear Medicine and Molecular Imaging & Gordon Center for Medical Imaging, Massachusetts General Hospital, 55 Fruit Street, Boston, Massachusetts, 02114, United States of America; Department of Radiology, Harvard Medical School, 55 Fruit Street, Boston, Massachusetts, 02114, United States of America
| | - Steven H Liang
- Division of Nuclear Medicine and Molecular Imaging & Gordon Center for Medical Imaging, Massachusetts General Hospital, 55 Fruit Street, Boston, Massachusetts, 02114, United States of America; Department of Radiology, Harvard Medical School, 55 Fruit Street, Boston, Massachusetts, 02114, United States of America
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14
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Parmar L, Fidalgo S, Yeoman MS, Patel BA. Chromatographic analysis of age-related changes in mucosal serotonin transmission in the murine distal ileum. Chem Cent J 2012; 6:31. [PMID: 22494644 PMCID: PMC3483693 DOI: 10.1186/1752-153x-6-31] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Accepted: 02/27/2012] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND In the upper bowel, alterations in motility and absorption of key nutrients have been observed as part of the normal ageing process. Serotonin (5-HT) is a key signalling molecule in the gastrointestinal tract and is known to influence motility, however little is known of how the ageing process alters 5-HT signalling processes in the bowel. RESULTS An isocratic chromatographic method was able to detect all 5-HT precursors and metabolites. Using extracellular and intracellular sampling approaches, we were able to monitor all key parameters associated with the transmission process. There was no alteration in the levels of tryptophan and 5-HTP between 3 and 18 month old animals. There was a significant increase in the ratio of 5-HT:5-HTP and an increase in intracellular 5-HT between 3 and 18 month old animals suggesting an increase in 5-HT synthesis. There was also a significant increase in extracellular 5-HT with age, suggesting increased 5-HT release. There was an age-related decrease in the ratio of intracellular 5-HIAA:extracellular 5-HT, whilst the amount of 5-HIAA did not change with age. In the presence of an increase in extracellular 5-HT, the lack of an age-related change in 5-HIAA is suggestive of a decrease in re-uptake via the serotonin transporter (SERT). CONCLUSIONS We have used intracellular and extracellular sampling to provide more insight into alterations in the neurotransmission process of 5-HT during normal ageing. We observed elevated 5-HT synthesis and release and a possible decrease in the activity of SERT. Taken together these changes lead to increased 5-HT availability and may alter motility function and could lead to the changes in adsorption observed in the elderly.
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Affiliation(s)
- Leena Parmar
- Centre for Biomedical and Health Sciences Research, University of Brighton, Brighton, BN2 4GJ, UK.
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15
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Booij J, Berendse HW. Monitoring therapeutic effects in Parkinson's disease by serial imaging of the nigrostriatal dopaminergic pathway. J Neurol Sci 2011; 310:40-3. [PMID: 21840542 DOI: 10.1016/j.jns.2011.07.029] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Revised: 06/03/2011] [Accepted: 07/19/2011] [Indexed: 10/16/2022]
Abstract
PET and SPECT are very sensitive techniques to detect in-vivo nigrostriatal degeneration in Parkinson's disease, even in the pre-motor phase of the disease. Furthermore, these techniques are able to measure disease progression. However, caution must be used in the interpretation of studies in which therapeutic effects in Parkinson's disease were also monitored by serial imaging of nigrostriatal neurons, as disparity between imaging and clinical outcomes has been reported in several clinical studies.
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Affiliation(s)
- Jan Booij
- Department of Nuclear Medicine, Academic Medical Center, University of Amsterdam, The Netherlands.
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16
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Klostermann EC, Braskie MN, Landau SM, O'Neil JP, Jagust WJ. Dopamine and frontostriatal networks in cognitive aging. Neurobiol Aging 2011; 33:623.e15-24. [PMID: 21511369 DOI: 10.1016/j.neurobiolaging.2011.03.002] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2010] [Revised: 01/11/2011] [Accepted: 03/01/2011] [Indexed: 11/17/2022]
Abstract
Recent studies have linked dopamine to differences in behavior and brain activity in normal individuals. We explored these relationships in older and younger adults by investigating how functional connectivity between the striatum and prefrontal cortex is related to caudate dopamine and verbal working memory task performance. We studied 12 young and 18 older participants with functional magnetic resonance imaging (fMRI) during this task, and used positron emission tomography with the tracer 6-[(18)F]-fluoro-L-m-tyrosine (FMT) to assess dopamine synthesis capacity. Younger adults had a greater extent of frontal caudate functional connectivity during the load-dependent delay period of the working memory task than the older participants. Across all subjects, the extent of this functional connectivity was negatively correlated with dopamine synthesis capacity, such that participants with the greatest connectivity had the lowest caudate 6-[(18)F]-fluoro-L-m-tyrosine (FMT) signal. Additionally, the extent of functional connectivity was positively correlated with working memory performance. Overall these data suggest interdependencies exist between frontostriatal functional connectivity, dopamine, and working memory performance and that this system is functioning suboptimally in normal aging.
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Affiliation(s)
- Ellen C Klostermann
- Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, CA 94720-3190, USA.
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17
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Boger HA, Mannangatti P, Samuvel DJ, Saylor AJ, Bender TS, McGinty JF, Fortress AM, Zaman V, Huang P, Middaugh LD, Randall PK, Jayanthi LD, Rohrer B, Helke KL, Granholm AC, Ramamoorthy S. Effects of brain-derived neurotrophic factor on dopaminergic function and motor behavior during aging. GENES BRAIN AND BEHAVIOR 2010; 10:186-98. [PMID: 20860702 DOI: 10.1111/j.1601-183x.2010.00654.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Brain-derived neurotrophic factor (BDNF) is critical in synaptic plasticity and in the survival and function of midbrain dopamine neurons. In this study, we assessed the effects of a partial genetic deletion of BDNF on motor function and dopamine (DA) neurotransmitter measures by comparing Bdnf(+/-) with wildtype mice (WT) at different ages. Bdnf(+/-) and WT mice had similar body weights until 12 months of age; however, at 21 months, Bdnf(+/-) mice were significantly heavier than WT mice. Horizontal and vertical motor activity was reduced for Bdnf(+/-) compared to WT mice, but was not influenced by age. Performance on an accelerating rotarod declined with age for both genotypes and was exacerbated for Bdnf(+/-) mice. Body weight did not correlate with any of the three behavioral measures studied. Dopamine neurotransmitter markers indicated no genotypic difference in striatal tyrosine hydroxylase, DA transporter (DAT) or vesicular monoamine transporter 2 (VMAT2) immunoreactivity at any age. However, DA transport via DAT (starting at 12 months) and VMAT2 (starting at 3 months) as well as KCl-stimulated DA release were reduced in Bdnf(+/-) mice and declined with age suggesting an increasingly important role for BDNF in the release and uptake of DA with the aging process. These findings suggest that a BDNF expression deficit becomes more critical to dopaminergic dynamics and related behavioral activities with increasing age.
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Affiliation(s)
- H A Boger
- Department of Neurosciences and the Center on Aging, Medical University of South Carolina, Charleston, SC 29425, USA
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18
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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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19
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Boger HA, Granholm AC, McGinty JF, Middaugh LD. A dual-hit animal model for age-related parkinsonism. Prog Neurobiol 2010; 90:217-29. [PMID: 19853012 PMCID: PMC3991553 DOI: 10.1016/j.pneurobio.2009.10.013] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2009] [Revised: 06/08/2009] [Accepted: 10/09/2009] [Indexed: 12/30/2022]
Abstract
Parkinson's disease is a neurological disorder which afflicts an increasing number of individuals. If the wider complex of extrapyramidal symptoms referred to as "age-related parkinsonism" is included, the incidence is near 50% of the population above 80 years of age. This review summarizes recent studies from our laboratories as well as other research groups in the quest to explore the multi-faceted etiology of age-related neurodegeneration, in general, and degeneration of the substantia nigra dopaminergic neurons, in particular. Our work during recent years has focused on assessment of potential interactive effects of a reduction in glial cell line-derived neurotrophic factor (GDNF) and the aging process (intrinsic factors) and early neurotoxin exposure (an extrinsic factor) on dopamine (DA) systems and the behaviors they mediate. The guiding hypothesis directing the research to be described was that a combination of the two factors would exacerbate the decline in the DA transmitter system function that occurs during aging. The results obtained were consistent with the well-established aging-related decline in function and structure of neurons utilizing DA as a transmitter and motor function, and extended knowledge by establishing that the genetic reduction of Gdnf exacerbated these aging related changes. Thus, GDNF reduction appears to increase the vulnerability of the DA neurons to the many different challenges associated with the aging process. Assessment of methamphetamine effects on young Gdnf(+/-) mice indicated that reduced GDNF availability increased the vulnerability of DA systems to this well-established neurotoxin. The work discussed in this review is consistent with earlier work demonstrating the importance of GDNF for maintenance of DA neurons and also provides a novel model for progressive DA degeneration and motor dysfunction.
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Affiliation(s)
- Heather A Boger
- Department of Neurosciences, Medical University of South Carolina, Charleston, SC 29425, United States
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20
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Johnston LC, Eberling J, Pivirotto P, Hadaczek P, Federoff HJ, Forsayeth J, Bankiewicz KS. Clinically relevant effects of convection-enhanced delivery of AAV2-GDNF on the dopaminergic nigrostriatal pathway in aged rhesus monkeys. Hum Gene Ther 2010; 20:497-510. [PMID: 19203243 DOI: 10.1089/hum.2008.137] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Growth factor therapy for Parkinson's disease offers the prospect of restoration of dopaminergic innervation and/or prevention of neurodegeneration. Safety and efficacy of an adeno-associated virus (AAV2) encoding human glial cell-derived neurotrophic factor (GDNF) was investigated in aged nonhuman primates. Positron emission tomography with 6-[(18)F]-fluoro-l-m-tyrosine (FMT-PET) in putamen was assessed 3 months before and after AAV2 infusion. In the right putamen, monkeys received either phosphate-buffered saline or low-dose (LD) or high-dose (HD) AAV2-GDNF. Monkeys that had received putaminal phosphate-buffered saline (PBS) infusions additionally received either PBS or HD AAV2-GDNF in the right substantia nigra (SN). The convection-enhanced delivery method used for infusion of AAV2-GDNF vector resulted in robust volume of GDNF distribution within the putamen. AAV2-GDNF increased FMT-PET uptake in the ipsilateral putamen as well as enhancing locomotor activity. Within the putamen and caudate, the HD gene transfer mediated intense GDNF fiber and extracellular immunoreactivity (IR). Retrograde and anterograde transport of GDNF to other brain regions was observed. AAV2-GDNF did not significantly affect dopamine in the ipsilateral putamen or caudate, but increased dopamine turnover in HD groups. HD putamen treatment increased the density of dopaminergic terminals in these regions. HD treatments, irrespective of the site of infusion, increased the number of nonpigmented TH-IR neurons in the SN. AAV2-GDNF gene transfer does not appear to elicit adverse effects, delivers therapeutic levels of GDNF within target brain areas, and enhances utilization of striatal dopamine and dopaminergic nigrostriatal innervation.
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Affiliation(s)
- Louisa C Johnston
- Department of Neurological Surgery, University of California San Francisco, San Francisco, CA 94103, USA
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21
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Wilcox CE, Braskie MN, Kluth JT, Jagust WJ. Overeating Behavior and Striatal Dopamine with 6-[F]-Fluoro-L-m-Tyrosine PET. J Obes 2010; 2010:909348. [PMID: 20798859 PMCID: PMC2925447 DOI: 10.1155/2010/909348] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2009] [Accepted: 02/23/2010] [Indexed: 11/29/2022] Open
Abstract
Eating behavior may be affected by dopamine synthesis capacity. In this study, 6-[(18)F]-fluoro-L-m-tyrosine (FMT) positron emission tomography (PET) uptake in striatal subregions was correlated with BMI (kg/m(2)) and an estimate of the frequency of prior weight loss attempts in 15 healthy subjects. BMI was negatively correlated with FMT uptake in the dorsal caudate. Although the association between BMI and FMT uptake in the dorsal caudate was not significant upon correction for age and sex, the association fell within the range of a statistical trend. Weight loss attempts divided by years trying was also negatively correlated with FMT uptake in the dorsal putamen (P = .05). These results suggest an association between low dorsal striatal presynaptic dopamine synthesis capacity and overeating behavior.
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Affiliation(s)
- Claire E. Wilcox
- Department of Psychiatry, University of California at San Francisco, 401 Parnassus Avenue, San Francisco, CA 94143, USA
- Helen Wills Neuroscience Institute, MC #3190, University of California at Berkeley, 132 Barker Hall, Berkeley, CA 94720-3192, USA
- Department of Psychiatry, School of Medicine, University of New Mexico, MSC09 5030, Albuquerque, NM 87131, USA
- *Claire E. Wilcox:
| | - Meredith N. Braskie
- Helen Wills Neuroscience Institute, MC #3190, University of California at Berkeley, 132 Barker Hall, Berkeley, CA 94720-3192, USA
| | - Jennifer T. Kluth
- Helen Wills Neuroscience Institute, MC #3190, University of California at Berkeley, 132 Barker Hall, Berkeley, CA 94720-3192, USA
| | - William J. Jagust
- Helen Wills Neuroscience Institute, MC #3190, University of California at Berkeley, 132 Barker Hall, Berkeley, CA 94720-3192, USA
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22
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Emborg ME, Moirano J, Raschke J, Bondarenko V, Zufferey R, Peng S, Ebert AD, Joers V, Roitberg B, Holden JE, Koprich J, Lipton J, Kordower JH, Aebischer P. Response of aged parkinsonian monkeys to in vivo gene transfer of GDNF. Neurobiol Dis 2009; 36:303-11. [PMID: 19660547 PMCID: PMC2989601 DOI: 10.1016/j.nbd.2009.07.022] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2008] [Revised: 07/27/2009] [Accepted: 07/28/2009] [Indexed: 01/22/2023] Open
Abstract
This study assessed the potential for functional and anatomical recovery of the diseased aged primate nigrostriatal system, in response to trophic factor gene transfer. Aged rhesus monkeys received a single intracarotid infusion of MPTP, followed one week later by MRI-guided stereotaxic intrastriatal and intranigral injections of lentiviral vectors encoding for glial derived neurotrophic factor (lenti-GDNF) or beta-galactosidase (lenti-LacZ). Functional analysis revealed that the lenti-GDNF, but not lenti-LacZ treated monkeys displayed behavioral improvements that were associated with increased fluorodopa uptake in the striatum ipsilateral to lenti-GDNF treatment. GDNF ELISA of striatal brain samples confirmed increased GDNF expression in lenti-GDNF treated aged animals that correlated with functional improvements and preserved nigrostriatal dopaminergic markers. Our results indicate that the aged primate brain challenged by MPTP administration has the potential to respond to trophic factor delivery and that the degree of neuroprotection depends on GDNF levels.
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Affiliation(s)
- M E Emborg
- Preclinical Parkinson's Research Program, Wisconsin National Primate Research Center, University of Wisconsin - Madison, 1223 Capitol Court, Madison, WI 53715, USA.
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23
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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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24
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Kumakura Y, Vernaleken I, Buchholz HG, Borghammer P, Danielsen E, Gründer G, Heinz A, Bartenstein P, Cumming P. Age-dependent decline of steady state dopamine storage capacity of human brain: an FDOPA PET study. Neurobiol Aging 2008; 31:447-63. [PMID: 18541344 DOI: 10.1016/j.neurobiolaging.2008.05.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2008] [Revised: 04/23/2008] [Accepted: 05/01/2008] [Indexed: 01/17/2023]
Abstract
Conventional indices of the utilization of FDOPA in living human brain have not consistently revealed important declines in dopamine function with normal aging. However, most methods of kinetic analysis have assumed irreversible trapping of decarboxylated FDOPA metabolites in brain, an assumption that is violated even in PET recordings of short duration. Therefore, we have developed methods for the calculation of steady-state storage of FDOPA together with its decarboxylated metabolites (V(d), mlg(-1)), based upon improved kinetic analysis of 120-min emission recordings. In a group of 28 normal male subjects, of age ranging from 23 to 73 years, the magnitude of V(d) in the striatum and in extrastriatal regions declined by approximately 10% with each decade. The utilization of FDOPA was also calculated by several conventional methods assuming irreversible trapping, i.e. the net blood brain clearance (K(in)(app), mlg(-1)min(-1)), the DOPA decarboxylase activity relative to a reference tissue input (k(3)(S), min(-1)), and relative to the arterial input (k(3)(D), min(-1)). None of these methods revealed an age-related decline in FDOPA utilization in the extended striatum, although the magnitude of K(in)(app) did decline in cerebral cortex. Thus, the capacity to synthesize [(18)F]fluorodopamine remained largely intact in striatum of the elderly subjects, but in the presence of a substantially increased rate of washout (k(loss)), which was evident in all brain regions examined. Consequently, the magnitude of V(d) declined with healthy aging, possibly reflecting impaired vesicular storage capacity, resulting in enhanced exposure of cytosolic [(18)F]fluorodopamine to monoamine oxidase.
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Affiliation(s)
- Yoshitaka Kumakura
- Centre for Functionally Integrative Neuroscience, Aarhus University, Aarhus C. 8000, Denmark.
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25
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Abstract
Nonhuman primate (NHP) models of Parkinson's disease (PD) play an essential role in the understanding of PD pathophysiology and the assessment of PD therapies. NHP research enabled the identification of environmental risk factors for the development of PD. Electrophysiological studies in NHP models of PD identified the neural circuit responsible for PD motor symptoms, and this knowledge led to the development of subthalamic surgical ablation and deep brain stimulation. Similar to human PD patients, parkinsonian monkeys are responsive to dopamine replacement therapies and present complications associated with their long-term use, a similarity that facilitated the assessment of new symptomatic treatments, such as dopaminergic agonists. New generations of compounds and novel therapies that use directed intracerebral delivery of drugs, cells, and viral vectors benefit from preclinical evaluation in NHP models of PD. There are several NHP models of PD, each with characteristics that make it suitable for the study of different aspects of the disease or potential new therapies. Investigators who use the models and peer scientists who evaluate their use need information about the strengths and limitations of the different PD models and their methods of evaluation. This article provides a critical review of available PD monkey models, their utilization, and how they compare to emerging views of PD as a multietiologic, multisystemic disease. The various models are particularly useful for representing different aspects of PD at selected time points. This conceptualization provides clues for the development of new NHP models and facilitates the clinical translation of findings. As ever, successful application of any model depends on matching the model to the scientific question to be answered. Adequate experimental designs, with multiple outcome measures of clinical relevance and an appropriate number of animals, are essential to minimize the limitations of models and increase their predictive clinical validity.
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Affiliation(s)
- Marina E Emborg
- Preclinical Parkinson's Research Program, Wisconsin National Primate Research Center, University of Wisconsin-Madison, 1223 Capitol Court, Madison, WI 53715, USA.
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26
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Honer M, Hengerer B, Blagoev M, Hintermann S, Waldmeier P, Schubiger PA, Ametamey SM. Comparison of [18F]FDOPA, [18F]FMT and [18F]FECNT for imaging dopaminergic neurotransmission in mice. Nucl Med Biol 2006; 33:607-14. [PMID: 16843835 DOI: 10.1016/j.nucmedbio.2006.04.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2005] [Revised: 04/03/2006] [Accepted: 04/11/2006] [Indexed: 11/23/2022]
Abstract
INTRODUCTION The clinically established positron emission tomography (PET) tracers 6-[(18)F]-fluoro-l-DOPA ([(18)F]FDOPA), 6-[(18)F]-fluoro-l-m-tyrosine ([(18)F]FMT) and 2beta-carbomethoxy-3beta-(4-chlorophenyl)-8-(2-[(18)F]-fluoroethyl)-nortropane ([(18)F]FECNT) serve as markers of presynaptic integrity of dopaminergic nerve terminals in humans. This study describes our efforts to adopt the methodology of human Parkinson's disease (PD) PET studies to mice. METHODS The PET imaging characteristics of [(18)F]FDOPA, [(18)F]FMT and [(18)F]FECNT were analyzed in healthy C57BL/6 mice using the dedicated small-animal PET tomograph quad-HIDAC. Furthermore, [(18)F]FECNT was tested in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD. RESULTS [(18)F]FDOPA and [(18)F]FMT failed to clearly visualize the mouse striatum, whereas PET experiments using [(18)F]FECNT proved that the employed methodology is capable of delineating the striatum in mice with exquisite resolution. Moreover, [(18)F]FECNT PET imaging of healthy and MPTP-lesioned mice demonstrated that the detection and quantification of striatal degeneration in lesioned mice can be accomplished. CONCLUSIONS This study shows the feasibility of using [(18)F]FECNT PET to analyze noninvasively the striatal degeneration in the MPTP mouse model of PD. This methodology can be therefore considered as a viable complement to established in vivo microdialysis and postmortem techniques.
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Affiliation(s)
- Michael Honer
- Center for Radiopharmaceutical Science of ETH, PSI and USZ, CH-8093 Zurich, Switzerland.
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DeJesus OT, Flores LG, Murali D, Converse AK, Bartlett RM, Barnhart TE, Oakes TR, Nickles RJ. Aromatic l-amino acid decarboxylase turnover in vivo in rhesus macaque striatum: A microPET study. Brain Res 2005; 1054:55-60. [PMID: 16055094 DOI: 10.1016/j.brainres.2005.06.086] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2005] [Accepted: 06/25/2005] [Indexed: 10/25/2022]
Abstract
The aromatic L-amino acid decarboxylase (AAAD) is involved in the de novo synthesis of dopamine, a neurotransmitter crucial in cognitive, neurobehavioral and motor functions. The goal of this study was to assess the in vivo turnover rate of AAAD enzyme protein in the rhesus macaque striatum by monitoring, using microPET imaging with the tracer [(18)F]fluoro-m-tyrosine (FMT), the recovery of enzyme activity after suicide inhibition. Results showed the AAAD turnover half-life to be about 86 h while total recovery was estimated to be 16 days after complete inhibition. Despite this relatively slow AAAD recovery, the animals displayed normal movement and behavior within 24 h. Based on the PET results, at 24 h, the animals have recovered about 20% of normal AAAD function. These findings show that normal movement and behavior do not depend on complete recovery of AAAD function but likely on pre-synaptic and post-synaptic compensatory mechanisms.
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Affiliation(s)
- O T DeJesus
- Medical Physics, University of Wisconsin Medical School, 1530 Medical Sciences Center, 1300 University Avenue, Madison, WI 53706, USA.
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DeJesus OT, Flores LG, Roberts AD, Dick DW, Bartlett RM, Murali D, Nickles RJ. Aromatic L-amino acid decarboxylase (AAAD) activity in rhesus macaque striatum after MAO-B inhibition by Ro 16-6491. Synapse 2005; 56:54-6. [PMID: 15700282 DOI: 10.1002/syn.20119] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- O T DeJesus
- Department of Medical Physics, University of Wisconsin Medical School, Madison, Wisconsin 53706, USA.
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Meltzer CC, Becker JT, Price JC, Moses-Kolko E. Positron emission tomography imaging of the aging brain. Neuroimaging Clin N Am 2003; 13:759-67. [PMID: 15024959 DOI: 10.1016/s1052-5149(03)00108-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
PET imaging provides a vital means to study the human brain in vivo in aging and early disease states. PET studies using selective markers for brain metabolism and neurotransmitter function have uncovered a wealth of information on healthy and pathologic brain aging, and its relationship to behavior and mood states. Recognition of inherent potential confounds in the use of PET in aging studies is essential to the proper interpretation of these data.
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Affiliation(s)
- Carolyn Cidis Meltzer
- Department of Radiology, University of Pittsburgh School of Medicine, CHP MT 3972, 200 Lothrop Street, Pittsburgh, PA 15213-2582, USA.
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Harada N, Nishiyama S, Satoh K, Fukumoto D, Kakiuchi T, Tsukada H. Age-related changes in the striatal dopaminergic system in the living brain: a multiparametric PET study in conscious monkeys. Synapse 2002; 45:38-45. [PMID: 12112412 DOI: 10.1002/syn.10082] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
In the present study, age-related changes in the striatal dopaminergic system were examined in the living brains of conscious young (6.2 +/- 1.5 years old) and aged (20.2 +/- 2.6 years old) monkeys (Macaca mulatta) using positron emission tomography (PET). L-[beta-(11)C]DOPA and [(11)C]beta-CFT were applied to determine dopamine presynaptic functions such as synthesis rate and transporter (DAT) availability, respectively. Striatal dopamine D(1)- (D(1)R) and D(2)-like receptor (D(2)R) binding were measured with [(11)C]SCH23390 and [(11)C]raclopride, respectively. Although the markers of presynaptic terminals showed parallel age-related declines, the reduction of dopamine synthesis rate measured with L-[beta-(11)C]DOPA was slightly smaller than that of DAT determined with [(11)C]beta-CFT. The binding of [(11)C]raclopride to D(2)R in vivo was significantly reduced with aging, while that of [(11)C]SCH23390 to D(1)R showed no such marked age-related reduction. When the DAT inhibitor GBR12909 (0.5 and 5 mg/kg) was administered, DAT availability, dopamine synthesis, and D(2)R binding were significantly decreased in a dose-dependent manner in both age groups; however, the degrees of the decreases in these parameters were significantly higher in young rather than in aged animals. Dopamine concentration in the striatal extracellular fluid (ECF), as measured by microdialysis, was increased by administration of GBR12909 in a dose-dependent manner and the degree of the increase in dopamine level decreased with age. These results demonstrate that age-related changes of dopamine neuronal functions were not limited to the resting condition but were also seen in the functional responses to the neurotransmitter modulation.
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Affiliation(s)
- Norihiro Harada
- Central Research Laboratory, Hamamatsu Photonics K.K., Shizuoka 434-8601, Japan
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31
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DeJesus OT, Shelton SE, Roberts AD, Nickles RJ, Holden JE. Effect of tetrabenazine on the striatal uptake of exogenous L-DOPA in vivo: a PET study in young and aged rhesus monkeys. Synapse 2002; 44:246-51. [PMID: 11984859 DOI: 10.1002/syn.10077] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The effect of tetrabenazine (TBZ) pretreatment on the striatal uptake of exogenous L-DOPA in vivo was assessed noninvasively in rhesus monkeys by positron emission tomography (PET) using the tracer [(18)F]-FluoroDOPA (FDOPA). Paired studies were done comparing baseline vs. TBZ treatment on the uptake of FDOPA, a measure of aromatic L-amino acid decarboxylase (AAAD) activity. Results show increased AAAD activity with TBZ treatment. These results suggest that the action of TBZ as a dopamine antagonist dominates more than its expected action as a potent vesicular monoamine transporter (VMAT2) inhibitor. Results also showed diminished responsivity of AAAD to TBZ challenge in aged monkey brain.
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Affiliation(s)
- Onofre T DeJesus
- Medical Physics Department, University of Wisconsin Medical School, 1530 Medical Sciences Center, 1300 University Avenue, Madison, WI 53706, USA.
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Peñuelas Sánchez I. [PET radiopharmaceuticals]. REVISTA ESPANOLA DE MEDICINA NUCLEAR 2001; 20:477-98; quiz 499-501. [PMID: 11578585 DOI: 10.1016/s0212-6982(01)71997-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- I Peñuelas Sánchez
- Unidad de Radiofarmacia, Servicio de Medicina Nuclear, Clínica Universitaria de Navarra, Spain.
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McConathy J, Kilts CD, Goodman MM. Radioligands for PET and SPECT Imaging of the central noradrenergic system. CNS Spectr 2001; 6:704-9. [PMID: 15520617 DOI: 10.1017/s1092852900001401] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
In the central nervous system, the neurotransmitter norepinephrine is involved in normal physiology, neuropsychiatric disorders, and the effects of numerous drugs. Although alterations of the central noradrenergic system are involved in the pathophysiology and pharmacotherapy of mood disorders, the basis and nature of these changes remain unresolved. Positron emission tomography (PET) and single photon emission computed tomography (SPECT) imaging agents will be valuable for further elucidating the roles of norepinephrine in health and disease. This review discusses PET and SPECT radioligands that have been developed for the enzymes, receptors, and transporters involved in noradrenergic neurotransmission. Currently, imaging agents that exhibit specific in vivo uptake in the brain have been described for monoamine oxidase A and beta-adrenergic receptors, but have not undergone detailed evaluation or experimental application. Based on the successful development and utilization of in vivo imaging agents for elements of the central dopaminergic and serotoninergic systems, PET and SPECT radioligands are expected to serve as new tools for studying the physiology, pathophysiology, and pharmacology of the central noradrenergic system.
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Affiliation(s)
- J McConathy
- Neuroscience Program, Emory University, Atlanta, GA, USA.
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Affiliation(s)
- Doris J. Doudet
- Neurodegenerative Disorders Center, Department of Medicine/Neurology, University of British Columbia, Vancouver, Canada
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