scholarly journals Lack of Age-Dependent Decrease in Dopamine D3 Receptor Availability: A [11C]-(+)-PHNO and [11C]-Raclopride Positron Emission Tomography Study

2015 ◽  
Vol 35 (11) ◽  
pp. 1812-1818 ◽  
Author(s):  
Shinichiro Nakajima ◽  
Fernando Caravaggio ◽  
Isabelle Boileau ◽  
Jun K Chung ◽  
Eric Plitman ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Ventral Striatum ◽  
Emission Tomography ◽  
Ventral Pallidum ◽  
Binding Potential ◽  
Healthy Humans ◽  
Positron Emission ◽  
Age Dependent ◽  
Dopamine D3 ◽  
The Relationship

Positron emission tomography with antagonist radiotracers has showed that striatal dopamine D2/3 receptor (D2/3R) availability decreases with age. However, no study has specifically assessed whether D2/3R availability decreases with age in healthy persons as measured with agonist radiotracers. Moreover, it is unknown whether D3R availability changes with age in healthy humans. Thus, we explored the relationship between age and D2/3R availability in healthy humans using the D3 receptor (D3R)-preferential agonist radiotracer [11C]-(+)-PHNO ( n = 72, mean ± s.d. age = 40 ± 15, range = 18 to 73) and the antagonist [11C]-Raclopride ( n = 70, mean ± s.d. age = 40 ± 14, range = 18 to 73) (both, n = 33). The contribution of D3R to the [11C]-(+)-PHNO signal varies across regions of interest; the substantia nigra and hypothalamus represent D3R-specific regions, the ventral pallidum, globus pallidus, and ventral striatum represent D2/3R-mixed regions, and the caudate and putamen represent D2 receptor (D2R)-specific regions. With [11C]-(+)-PHNO, a negative correlation was observed between age and nondisplaceable binding potential (BPND) in the caudate ( r(70) = −0.32, P = 0.005). No correlations were observed in the other regions. With [11C]-Raclopride, negative correlations were observed between age and BPND in the caudate ( r(68) = −0.50, P < 0.001), putamen ( r(68) = −0.41, P < 0.001), and ventral striatum ( r(68) = −0.43, P < 0.001). In conclusion, in contrast with the age-dependent decrease in D2R availability, these findings suggest that D3R availability does not change with age.

scholarly journals Imaging Human Mesolimbic Dopamine Transmission with Positron Emission Tomography: I. Accuracy and Precision of D2 Receptor Parameter Measurements in Ventral Striatum

2001 ◽  
Vol 21 (9) ◽  
pp. 1034-1057 ◽  
Author(s):  
Osama Mawlawi ◽  
Diana Martinez ◽  
Mark Slifstein ◽  
Allegra Broft ◽  
Rano Chatterjee ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
High Resolution ◽  
Ventral Striatum ◽  
Critical Role ◽  
Intraclass Correlation ◽  
Emission Tomography ◽  
Binding Potential ◽  
Positron Emission ◽  
Accuracy And Precision ◽  
Dopamine Transmission

Dopamine transmission in the ventral striatum (VST), a structure which includes the nucleus accumbens, ventral caudate, and ventral putamen, plays a critical role in the pathophysiology of psychotic states and in the reinforcing effects of virtually all drugs of abuse. The aim of this study was to assess the accuracy and precision of measurements of D2 receptor availability in the VST obtained with positron emission tomography on the high-resolution ECAT EXACT HR+ scanner (Siemens Medical Systems, Knoxville, TN, U.S.A.). A method was developed for identification of the boundaries of the VST on coregistered high-resolution magnetic resonance imaging scans. Specific-to-nonspecific partition coefficient (V3″) and binding potential (BP) of [11C]raclopride were measured twice in 10 subjects, using the bolus plus constant infusion method. [11C]Raclopride V3″ in the VST (1.86 ± 0.29) was significantly lower than in the dorsal caudate (DCA, 2.33 ± 0.28) and dorsal putamen (DPU, 2.99 ± 0.26), an observation consistent with postmortem studies. The reproducibility of V3″ and BP were appropriate and similar in VST (V3″ test–retest variability of 8.2% ± 6.2%, intraclass correlation coefficient = 0.83), DCA (7.7% ± 5.1%, 0.77), DPU (6.0% ± 4.1%, 0.71), and striatum as a whole (6.3% ± 4.1%, 0.78). Partial volume effects analysis revealed that activities in the VST were significantly contaminated by counts spilling over from the adjacent DCA and DPU: 70% ± 5% of the specific binding measured in the VST originated from D2 receptors located in the VST, whereas 12% ± 3% and 18% ± 3% were contributed by D2 receptors in the DCA and DPU, respectively. Thus, accuracy of D2 receptor measurement is improved by correction for partial voluming effects. The demonstration of an appropriate accuracy and precision of D2 receptor measurement with [11C]raclopride in the VST is the first critical step toward the use of this ligand in the study of synaptic dopamine transmission at D2 receptors in the VST using endogenous competition techniques.

scholarly journals Positron Emission Tomography Quantification of [11C]-DASB Binding to the Human Serotonin Transporter: Modeling Strategies

2001 ◽  
Vol 21 (11) ◽  
pp. 1342-1353 ◽  
Author(s):  
Nathalie Ginovart ◽  
Alan A. Wilson ◽  
Jeffrey H. Meyer ◽  
Doug Hussey ◽  
Sylvain Houle
Keyword(s):  
Positron Emission Tomography ◽  
Serotonin Transporter ◽  
Quantitative Methods ◽  
Goodness Of Fit ◽  
Emission Tomography ◽  
Binding Potential ◽  
Reference Region ◽  
Time Activity ◽  
Healthy Humans ◽  
Positron Emission

[11C]-DASB, namely [11C]-3-amino-4-(2-dimethylaminomethyl-phenylsulfanyl)-benzonitrile, is a new highly selective radioligand for the in vivo visualization of the serotonin transporter (SERT) using positron emission tomography (PET). The current study evaluates different kinetic modeling strategies for quantification of [11C]-DASB binding in five healthy humans. Kinetic analyses of tissue data were performed with a one-tissue (1CM) and a two-tissue (2CM) compartment model. Time-activity curves were well described by a 1CM for all regions. A 2CM model with four parameters failed to converge reliably. Reliable fits of the data were obtained only if no more than three parameters were allowed to vary. However, even then, the rate constants k3 and k4 were estimated with poor precision. Only the ratio k3/k4 was stable. Goodness of fit was not improved by using a 2CM as compared with a 1CM. The minimal study duration required to obtain stable k3/k4 estimates was 80 minutes. For routine use of [11C]-DASB, several simplified methods using the cerebellum as a reference region to estimate nonspecific binding were also evaluated. The transient equilibrium, the linear graphical analysis, the ratio of target to reference region, and the simplified reference tissue methods all gave binding potential values consistent with those obtained with the 2CM. The suitability of [11C]-DASB for research on the SERT using PET is thus supported by the observations that tissue data can be described using a kinetic analysis and that simplified quantitative methods, using the cerebellum as reference, provide reliable estimates of SERT binding parameters.

scholarly journals Effects of an Adenosine A2A Receptor Antagonist on Striatal Dopamine D2-Type Receptor Availability: A Randomized Control Study Using Positron Emission Tomography

2021 ◽  
Vol 15 ◽  
Author(s):  
Kyoji Okita ◽  
Koichi Kato ◽  
Yoko Shigemoto ◽  
Noriko Sato ◽  
Toshihiko Matsumoto ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Substance Use ◽  
Receptor Antagonist ◽  
Substance Use Disorders ◽  
Emission Tomography ◽  
Binding Potential ◽  
Dopamine D2 ◽  
Positron Emission ◽  
A2a Receptor ◽  
Type Receptor

Introduction: Altered dopaminergic neurotransmission, especially in the functioning of dopamine D2-type receptors, is considered central to the etiology of a variety of neuropsychiatric disorders. In particular, individuals with substance use disorders have been consistently observed to exhibit lower D2-type receptor availability (quantified as binding potential; BPND) using positron emission tomography (PET). Upregulation of D2-type receptor density thus may therefore provide a therapeutic effect for substance use disorders. Importantly, in vitro studies reveal that D2 receptors coexist with adenosine 2A (A2A) receptors to form the highest density of heteromers in the whole striatum, and there is a functional interaction between these two receptors. As such, blockade of A2A receptor’s function may prevent D2 receptor downregulation, yet no study has currently examined this hypothesis in humans.Methods and Analysis: This double-blind, randomized controlled trial aims to evaluate the effect of the A2A receptor antagonist istradefylline (compared to placebo) on both dopamine D2-type receptor availability in the human brain and on neuropsychological measurements of impulsivity. It is hypothesized that istradefylline will both increase striatal D2-type BPND and improve control of impulsivity more than placebo. Forty healthy participants, aged 20–65 with no history of psychiatric or neurological disorders, will be recruited and randomized into two groups and will undergo [11C]raclopride PET, once before and once after administration of either 40 mg/day istradefylline or placebo for 2 weeks. Neuropsychological measurements will be administered on the same days of the PET scans.Ethics and Dissemination: The study protocol was approved by the Certified Review Boards (CRB) of National Center of Neurology and Psychiatry (CR18-011) and prospectively registered with the Japan Registry of Clinical Trials (jRCTs031180131; https://jrct.niph.go.jp/latest-detail/jRCTs031180131). The findings of this study will be disseminated through peer reviewed scientific journals and conferences.Clinical Trial Registration:www.ClinicalTrials.gov, identifier jRCTs031180131.

scholarly journals Quantitation of Translocator Protein Binding in Human Brain with the Novel Radioligand [18F]-FEPPA and Positron Emission Tomography

2011 ◽  
Vol 31 (8) ◽  
pp. 1807-1816 ◽  
Author(s):  
Pablo M Rusjan ◽  
Alan A Wilson ◽  
Peter M Bloomfield ◽  
Irina Vitcu ◽  
Jeffrey H Meyer ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Human Brain ◽  
Specific Binding ◽  
Compartment Model ◽  
Distribution Volume ◽  
Translocator Protein ◽  
Emission Tomography ◽  
Binding Potential ◽  
Specific Distribution ◽  
Positron Emission

This article describes the kinetic modeling of [18F]-FEPPA binding to translocator protein 18 kDa in the human brain using high-resolution research tomograph (HRRT) positron emission tomography. Positron emission tomography scans were performed in 12 healthy volunteers for 180 minutes. A two-tissue compartment model (2-CM) provided, with no exception, better fits to the data than a one-tissue model. Estimates of total distribution volume ( VT), specific distribution volume ( VS), and binding potential ( BPND) demonstrated very good identifiability (based on coefficient of variation ( COV)) for all the regions of interest (ROIs) in the gray matter ( COV VT < 7%, COV VS < 8%, COV BPND < 11%). Reduction of the length of the scan to 2 hours is feasible as VS and VT showed only a small bias (6% and 7.5%, respectively). Monte Carlo simulations showed that, even under conditions of a 500% increase in specific binding, the identifiability of VT and VS was still very good with COV<10%, across high-uptake ROIs. The excellent identifiability of VT values obtained from an unconstrained 2-CM with data from a 2-hour scan support the use of VT as an appropriate and feasible outcome measure for [18F]-FEPPA.

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