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Xu J. Dopamine D3 Receptor in Parkinson Disease: A Prognosis Biomarker and an Intervention Target. Curr Top Behav Neurosci 2023; 60:89-107. [PMID: 35711029 PMCID: PMC10034716 DOI: 10.1007/7854_2022_373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Parkinson disease (PD) dementia, pathologically featured as nigrostriatal dopamine (DA) neuronal loss with motor and non-motor manifestations, leads to substantial disability and economic burden. DA therapy targets the DA D3 receptor (D3R) with high affinity and selectivity. The pathological involvement of D3R is evidenced as an effective biomarker for disease progression and DA agnostic interventions, with compensations of increased DA, decreased aggregates of α-synuclein (α-Syn), enhanced secretion of brain-derived neurotrophic factors (BDNF), attenuation of neuroinflammation and oxidative damage, and promoting neurogenesis in the brain. D3R also interacts with D1R to reduce PD-associated motor symptoms and alleviate the side effects of levodopa (L-DOPA) treatment. We recently found that DA D2 receptor (D2R) density decreases in the late-stage PDs, while high D3R or DA D1 receptor (D1R) + D3R densities in the postmortem PD brains correlate with survival advantages. These new essential findings warrant renewed investigations into the understanding of D3R neuron populations and their cross-sectional and longitudinal regulations in PD progression.
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Affiliation(s)
- Jinbin Xu
- Division of Radiological Sciences, Department of Radiology, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO, USA.
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2
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Subburaju S, Sromek AW, Seeman P, Neumeyer JL. The High Affinity Dopamine D 2 Receptor Agonist MCL-536: A New Tool for Studying Dopaminergic Contribution to Neurological Disorders. ACS Chem Neurosci 2021; 12:1428-1437. [PMID: 33844498 DOI: 10.1021/acschemneuro.1c00094] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The dopamine D2 receptor exists in two different states, D2high and D2low; the former is the functional form of the D2 receptor and associates with intracellular G-proteins. The D2 agonist [3H]MCL-536 has high affinity for the D2 receptor (Kd 0.8 nM) and potently displaces the binding of (R-(-)-N-n-propylnorapomorphine (NPA; Ki 0.16 nM) and raclopride (Ki 0.9 nM) in competition binding assays. Here, we further characterize [3H]MCL-536. [3H]MCL-536 was metabolically stable, with about 75% of the compound remaining intact after 1 h incubation with human liver microsomes. Blood-brain barrier penetration in rats was good, attaining at 15 min a % injected dose per gram of wet tissue (%ID/g) of 0.28 in males versus 0.42 in females in the striatum. Specific uptake ratios ([%ID/g striatum]/[%ID/g cerebellum]) were stable in males during the first 60 min and in females up to 15-30 min. The D2-rich striatum exhibited the highest uptake and slowest washout compared to D2-poor cortex or cerebellum. In peripheral organs, uptake peaked at 15 min but declined to baseline at 60 min, indicating good clearance from the body. In vitro autoradiography on transaxial and coronal brain sections showed specific binding of [3H]MCL-536, which was abolished by preincubation with D2/D3 ligands sulpiride, NPA, and raclopride and in the presence of the stable GTP analogue guanylylimidodiphosphate. In amphetamine-sensitized animals, striatal binding was higher than in controls, indicating specificity for the D2high receptor state. [3H]MCL-536's unique properties make it a valuable tool for research on neurological disorders involving the dopaminergic system like Parkinson's disease or schizophrenia.
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Affiliation(s)
- Sivan Subburaju
- Division of Basic Neuroscience, Medicinal Chemistry Laboratory, McLean Hospital, Belmont, Massachusetts 02478, United States
- Department of Psychiatry, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Anna W. Sromek
- Division of Basic Neuroscience, Medicinal Chemistry Laboratory, McLean Hospital, Belmont, Massachusetts 02478, United States
- Department of Psychiatry, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Philip Seeman
- Departments of Pharmacology and Psychiatry, University of Toronto, 260 Heath St. West, unit 605, Toronto, Ontario M5P 3L6, Canada
| | - John L. Neumeyer
- Division of Basic Neuroscience, Medicinal Chemistry Laboratory, McLean Hospital, Belmont, Massachusetts 02478, United States
- Department of Psychiatry, Harvard Medical School, Boston, Massachusetts 02115, United States
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Dopamine D 2 Receptor Agonist Binding Kinetics-Role of a Conserved Serine Residue. Int J Mol Sci 2021; 22:ijms22084078. [PMID: 33920848 PMCID: PMC8071183 DOI: 10.3390/ijms22084078] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 04/06/2021] [Accepted: 04/13/2021] [Indexed: 01/03/2023] Open
Abstract
The forward (kon) and reverse (koff) rate constants of drug–target interactions have important implications for therapeutic efficacy. Hence, time-resolved assays capable of measuring these binding rate constants may be informative to drug discovery efforts. Here, we used an ion channel activation assay to estimate the kons and koffs of four dopamine D2 receptor (D2R) agonists; dopamine (DA), p-tyramine, (R)- and (S)-5-OH-dipropylaminotetralin (DPAT). We further probed the role of the conserved serine S1935.42 by mutagenesis, taking advantage of the preferential interaction of (S)-, but not (R)-5-OH-DPAT with this residue. Results suggested similar koffs for the two 5-OH-DPAT enantiomers at wild-type (WT) D2R, both being slower than the koffs of DA and p-tyramine. Conversely, the kon of (S)-5-OH-DPAT was estimated to be higher than that of (R)-5-OH-DPAT, in agreement with the higher potency of the (S)-enantiomer. Furthermore, S1935.42A mutation lowered the kon of (S)-5-OH-DPAT and reduced the potency difference between the two 5-OH-DPAT enantiomers. Kinetic Kds derived from the koff and kon estimates correlated well with EC50 values for all four compounds across four orders of magnitude, strengthening the notion that our assay captured meaningful information about binding kinetics. The approach presented here may thus prove valuable for characterizing D2R agonist candidate drugs.
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Colom M, Vidal B, Zimmer L. Is There a Role for GPCR Agonist Radiotracers in PET Neuroimaging? Front Mol Neurosci 2019; 12:255. [PMID: 31680859 PMCID: PMC6813225 DOI: 10.3389/fnmol.2019.00255] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Accepted: 10/02/2019] [Indexed: 12/30/2022] Open
Abstract
Positron emission tomography (PET) is a molecular imaging modality that enables in vivo exploration of metabolic processes and especially the pharmacology of neuroreceptors. G protein-coupled receptors (GPCRs) play an important role in numerous pathophysiologic disorders of the central nervous system. Thus, they are targets of choice in PET imaging to bring proof concept of change in density in pathological conditions or in pharmacological challenge. At present, most radiotracers are antagonist ligands. In vitro data suggest that properties differ between GPCR agonists and antagonists: antagonists bind to receptors with a single affinity, whereas agonists are characterized by two different affinities: high affinity for receptors that undergo functional coupling to G-proteins, and low affinity for those that are not coupled. In this context, agonist radiotracers may be useful tools to give functional images of GPCRs in the brain, with high sensitivity to neurotransmitter release. Here, we review all existing PET radiotracers used from animals to humans and their role for understanding the ligand-receptor paradigm of GPCR in comparison with corresponding antagonist radiotracers.
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Affiliation(s)
- Matthieu Colom
- Lyon Neuroscience Research Center, INSERM, CNRS, Université de Lyon, Lyon, France.,CERMEP, Hospices Civils de Lyon, Bron, France
| | - Benjamin Vidal
- Lyon Neuroscience Research Center, INSERM, CNRS, Université de Lyon, Lyon, France
| | - Luc Zimmer
- Lyon Neuroscience Research Center, INSERM, CNRS, Université de Lyon, Lyon, France.,CERMEP, Hospices Civils de Lyon, Bron, France.,Institut National des Sciences et Techniques Nucléaires, CEA Saclay, Gif-sur-Yvette, France
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Shalgunov V, van Waarde A, Booij J, Michel MC, Dierckx RAJO, Elsinga PH. Hunting for the high-affinity state of G-protein-coupled receptors with agonist tracers: Theoretical and practical considerations for positron emission tomography imaging. Med Res Rev 2018; 39:1014-1052. [PMID: 30450619 PMCID: PMC6587759 DOI: 10.1002/med.21552] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 10/02/2018] [Accepted: 10/19/2018] [Indexed: 12/15/2022]
Abstract
The concept of the high‐affinity state postulates that a certain subset of G‐protein‐coupled receptors is primarily responsible for receptor signaling in the living brain. Assessing the abundance of this subset is thus potentially highly relevant for studies concerning the responses of neurotransmission to pharmacological or physiological stimuli and the dysregulation of neurotransmission in neurological or psychiatric disorders. The high‐affinity state is preferentially recognized by agonists in vitro. For this reason, agonist tracers have been developed as tools for the noninvasive imaging of the high‐affinity state with positron emission tomography (PET). This review provides an overview of agonist tracers that have been developed for PET imaging of the brain, and the experimental paradigms that have been developed for the estimation of the relative abundance of receptors configured in the high‐affinity state. Agonist tracers appear to be more sensitive to endogenous neurotransmitter challenge than antagonists, as was originally expected. However, other expectations regarding agonist tracers have not been fulfilled. Potential reasons for difficulties in detecting the high‐affinity state in vivo are discussed.
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Affiliation(s)
- Vladimir Shalgunov
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Aren van Waarde
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Jan Booij
- Department of Radiology and Nuclear Medicine, Amsterdam University Medical Centers, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Martin C Michel
- Department of Pharmacology, Johannes Gutenberg University, Mainz, Germany
| | - Rudi A J O Dierckx
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.,Department of Nuclear Medicine, Ghent University, University Hospital, Ghent, Belgium
| | - Philip H Elsinga
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
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Subburaju S, Sromek AW, Seeman P, Neumeyer JL. New Dopamine D2 Receptor Agonist, [ 3H]MCL-536, for Detecting Dopamine D2high Receptors in Vivo. ACS Chem Neurosci 2018; 9:1283-1289. [PMID: 29641175 DOI: 10.1021/acschemneuro.8b00096] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Increases in the D2 receptor high affinity state are associated with certain neurological disorders. We synthesized and characterized the high-affinity D2high ligand [3H]MCL-536 in competition binding against the D2/3 agonist R-(-)- N- n-propylnorapomorphine (NPA) and the D2/3 antagonist raclopride. The total binding of [3H]MCL-536 (minus that in the presence of 100 nM NPA) was measured by saturation binding in CHO cells expressing human D2long; the data yielded separable, nonsaturable nonspecific, and saturable specific components. The former represents an aporphine site common to NPA and [3H]MCL-536. The latter indicated specific binding to the total D2 receptors (both high and low-affinity states). [3H]MCL-536 had a Kd of 0.8 nM. In competition binding, NPA had a Ki of 0.16 nM, and raclopride had a Ki of 0.9 nM. Co-incubation with guanylylimidodiphosphate abolished binding to D2high. This unique profile makes radiolabeled MCL-536 a versatile tool for diagnostics and therapeutics, and may quantify D2high sites in schizophrenia and PD patients in vivo.
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Affiliation(s)
- Sivan Subburaju
- Division of Basic Neuroscience, Medicinal Chemistry Laboratory, McLean Hospital, Belmont, Massachusetts 02478, United States
- Department of Psychiatry, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Anna W. Sromek
- Division of Basic Neuroscience, Medicinal Chemistry Laboratory, McLean Hospital, Belmont, Massachusetts 02478, United States
- Department of Psychiatry, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Philip Seeman
- Departments of Pharmacology and Psychiatry, University of Toronto, 260 Heath St. West, unit 605, Toronto, Ontario Canada M5P 3L6
| | - John L. Neumeyer
- Division of Basic Neuroscience, Medicinal Chemistry Laboratory, McLean Hospital, Belmont, Massachusetts 02478, United States
- Department of Psychiatry, Harvard Medical School, Boston, Massachusetts 02115, United States
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7
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Kubota M, Nagashima T, Takano H, Kodaka F, Fujiwara H, Takahata K, Moriguchi S, Kimura Y, Higuchi M, Okubo Y, Takahashi H, Ito H, Suhara T. Affinity States of Striatal Dopamine D2 Receptors in Antipsychotic-Free Patients with Schizophrenia. Int J Neuropsychopharmacol 2017; 20:928-935. [PMID: 29016872 PMCID: PMC5737675 DOI: 10.1093/ijnp/pyx063] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Accepted: 07/19/2017] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Dopamine D2 receptors are reported to have high-affinity (D2High) and low-affinity (D2Low) states. Although an increased proportion of D2High has been demonstrated in animal models of schizophrenia, few clinical studies have investigated this alteration of D2High in schizophrenia in vivo. METHODS Eleven patients with schizophrenia, including 10 antipsychotic-naive and 1 antipsychotic-free individuals, and 17 healthy controls were investigated. Psychopathology was assessed by Positive and Negative Syndrome Scale, and a 5-factor model was used. Two radioligands, [11C]raclopride and [11C]MNPA, were employed to quantify total dopamine D2 receptor and D2High, respectively, in the striatum by measuring their binding potentials. Binding potential values of [11C]raclopride and [11C]MNPA and the binding potential ratio of [11C]MNPA to [11C]raclopride in the striatal subregions were statistically compared between the 2 diagnostic groups using multivariate analysis of covariance controlling for age, gender, and smoking. Correlations between binding potential and Positive and Negative Syndrome Scale scores were also examined. RESULTS Multivariate analysis of covariance demonstrated a significant effect of diagnosis (schizophrenia and control) on the binding potential ratio (P=.018), although the effects of diagnosis on binding potential values obtained with either [11C]raclopride or [11C]MNPA were nonsignificant. Posthoc test showed that the binding potential ratio was significantly higher in the putamen of patients (P=.017). The Positive and Negative Syndrome Scale "depressed" factor in patients was positively correlated with binding potential values of both ligands in the caudate. CONCLUSIONS The present study indicates the possibilities of: (1) a higher proportion of D2High in the putamen despite unaltered amounts of total dopamine D2 receptors; and (2) associations between depressive symptoms and amounts of caudate dopamine D2 receptors in patients with schizophrenia.
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Affiliation(s)
- Manabu Kubota
- Department of Functional Brain Imaging Research, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan (Drs Kubota, Nagashima, Takano, Kodaka, Fujiwara, Moriguchi, Kimura, Higuchi, Takahashi, Ito, and Suhara); Department of Psychiatry, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan (Dr Takano); Department of Psychiatry, Jikei University School of Medicine, Tokyo, Japan (Dr Kodaka); Department of Clinical and Experimental Neuroimaging, Center for Development of Advanced Medicine for Dementia, National Center for Geriatrics and Gerontology, Obu, Japan (Dr Kimura); Department of Neuropsychiatry, Nippon Medical School, Tokyo, Japan (Dr Okubo); Department of Psychiatry, Graduate School of Medicine, Kyoto University, Kyoto, Japan (Dr Takahashi); Department of Radiology, School of Medicine, Fukushima Medical University, Fukushima, Japan (Dr Ito)
| | - Tomohisa Nagashima
- Department of Functional Brain Imaging Research, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan (Drs Kubota, Nagashima, Takano, Kodaka, Fujiwara, Moriguchi, Kimura, Higuchi, Takahashi, Ito, and Suhara); Department of Psychiatry, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan (Dr Takano); Department of Psychiatry, Jikei University School of Medicine, Tokyo, Japan (Dr Kodaka); Department of Clinical and Experimental Neuroimaging, Center for Development of Advanced Medicine for Dementia, National Center for Geriatrics and Gerontology, Obu, Japan (Dr Kimura); Department of Neuropsychiatry, Nippon Medical School, Tokyo, Japan (Dr Okubo); Department of Psychiatry, Graduate School of Medicine, Kyoto University, Kyoto, Japan (Dr Takahashi); Department of Radiology, School of Medicine, Fukushima Medical University, Fukushima, Japan (Dr Ito)
| | - Harumasa Takano
- Department of Functional Brain Imaging Research, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan (Drs Kubota, Nagashima, Takano, Kodaka, Fujiwara, Moriguchi, Kimura, Higuchi, Takahashi, Ito, and Suhara); Department of Psychiatry, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan (Dr Takano); Department of Psychiatry, Jikei University School of Medicine, Tokyo, Japan (Dr Kodaka); Department of Clinical and Experimental Neuroimaging, Center for Development of Advanced Medicine for Dementia, National Center for Geriatrics and Gerontology, Obu, Japan (Dr Kimura); Department of Neuropsychiatry, Nippon Medical School, Tokyo, Japan (Dr Okubo); Department of Psychiatry, Graduate School of Medicine, Kyoto University, Kyoto, Japan (Dr Takahashi); Department of Radiology, School of Medicine, Fukushima Medical University, Fukushima, Japan (Dr Ito)
| | - Fumitoshi Kodaka
- Department of Functional Brain Imaging Research, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan (Drs Kubota, Nagashima, Takano, Kodaka, Fujiwara, Moriguchi, Kimura, Higuchi, Takahashi, Ito, and Suhara); Department of Psychiatry, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan (Dr Takano); Department of Psychiatry, Jikei University School of Medicine, Tokyo, Japan (Dr Kodaka); Department of Clinical and Experimental Neuroimaging, Center for Development of Advanced Medicine for Dementia, National Center for Geriatrics and Gerontology, Obu, Japan (Dr Kimura); Department of Neuropsychiatry, Nippon Medical School, Tokyo, Japan (Dr Okubo); Department of Psychiatry, Graduate School of Medicine, Kyoto University, Kyoto, Japan (Dr Takahashi); Department of Radiology, School of Medicine, Fukushima Medical University, Fukushima, Japan (Dr Ito)
| | - Hironobu Fujiwara
- Department of Functional Brain Imaging Research, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan (Drs Kubota, Nagashima, Takano, Kodaka, Fujiwara, Moriguchi, Kimura, Higuchi, Takahashi, Ito, and Suhara); Department of Psychiatry, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan (Dr Takano); Department of Psychiatry, Jikei University School of Medicine, Tokyo, Japan (Dr Kodaka); Department of Clinical and Experimental Neuroimaging, Center for Development of Advanced Medicine for Dementia, National Center for Geriatrics and Gerontology, Obu, Japan (Dr Kimura); Department of Neuropsychiatry, Nippon Medical School, Tokyo, Japan (Dr Okubo); Department of Psychiatry, Graduate School of Medicine, Kyoto University, Kyoto, Japan (Dr Takahashi); Department of Radiology, School of Medicine, Fukushima Medical University, Fukushima, Japan (Dr Ito)
| | - Keisuke Takahata
- Department of Functional Brain Imaging Research, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan (Drs Kubota, Nagashima, Takano, Kodaka, Fujiwara, Moriguchi, Kimura, Higuchi, Takahashi, Ito, and Suhara); Department of Psychiatry, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan (Dr Takano); Department of Psychiatry, Jikei University School of Medicine, Tokyo, Japan (Dr Kodaka); Department of Clinical and Experimental Neuroimaging, Center for Development of Advanced Medicine for Dementia, National Center for Geriatrics and Gerontology, Obu, Japan (Dr Kimura); Department of Neuropsychiatry, Nippon Medical School, Tokyo, Japan (Dr Okubo); Department of Psychiatry, Graduate School of Medicine, Kyoto University, Kyoto, Japan (Dr Takahashi); Department of Radiology, School of Medicine, Fukushima Medical University, Fukushima, Japan (Dr Ito)
| | - Sho Moriguchi
- Department of Functional Brain Imaging Research, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan (Drs Kubota, Nagashima, Takano, Kodaka, Fujiwara, Moriguchi, Kimura, Higuchi, Takahashi, Ito, and Suhara); Department of Psychiatry, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan (Dr Takano); Department of Psychiatry, Jikei University School of Medicine, Tokyo, Japan (Dr Kodaka); Department of Clinical and Experimental Neuroimaging, Center for Development of Advanced Medicine for Dementia, National Center for Geriatrics and Gerontology, Obu, Japan (Dr Kimura); Department of Neuropsychiatry, Nippon Medical School, Tokyo, Japan (Dr Okubo); Department of Psychiatry, Graduate School of Medicine, Kyoto University, Kyoto, Japan (Dr Takahashi); Department of Radiology, School of Medicine, Fukushima Medical University, Fukushima, Japan (Dr Ito)
| | - Yasuyuki Kimura
- Department of Functional Brain Imaging Research, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan (Drs Kubota, Nagashima, Takano, Kodaka, Fujiwara, Moriguchi, Kimura, Higuchi, Takahashi, Ito, and Suhara); Department of Psychiatry, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan (Dr Takano); Department of Psychiatry, Jikei University School of Medicine, Tokyo, Japan (Dr Kodaka); Department of Clinical and Experimental Neuroimaging, Center for Development of Advanced Medicine for Dementia, National Center for Geriatrics and Gerontology, Obu, Japan (Dr Kimura); Department of Neuropsychiatry, Nippon Medical School, Tokyo, Japan (Dr Okubo); Department of Psychiatry, Graduate School of Medicine, Kyoto University, Kyoto, Japan (Dr Takahashi); Department of Radiology, School of Medicine, Fukushima Medical University, Fukushima, Japan (Dr Ito)
| | - Makoto Higuchi
- Department of Functional Brain Imaging Research, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan (Drs Kubota, Nagashima, Takano, Kodaka, Fujiwara, Moriguchi, Kimura, Higuchi, Takahashi, Ito, and Suhara); Department of Psychiatry, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan (Dr Takano); Department of Psychiatry, Jikei University School of Medicine, Tokyo, Japan (Dr Kodaka); Department of Clinical and Experimental Neuroimaging, Center for Development of Advanced Medicine for Dementia, National Center for Geriatrics and Gerontology, Obu, Japan (Dr Kimura); Department of Neuropsychiatry, Nippon Medical School, Tokyo, Japan (Dr Okubo); Department of Psychiatry, Graduate School of Medicine, Kyoto University, Kyoto, Japan (Dr Takahashi); Department of Radiology, School of Medicine, Fukushima Medical University, Fukushima, Japan (Dr Ito)
| | - Yoshiro Okubo
- Department of Functional Brain Imaging Research, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan (Drs Kubota, Nagashima, Takano, Kodaka, Fujiwara, Moriguchi, Kimura, Higuchi, Takahashi, Ito, and Suhara); Department of Psychiatry, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan (Dr Takano); Department of Psychiatry, Jikei University School of Medicine, Tokyo, Japan (Dr Kodaka); Department of Clinical and Experimental Neuroimaging, Center for Development of Advanced Medicine for Dementia, National Center for Geriatrics and Gerontology, Obu, Japan (Dr Kimura); Department of Neuropsychiatry, Nippon Medical School, Tokyo, Japan (Dr Okubo); Department of Psychiatry, Graduate School of Medicine, Kyoto University, Kyoto, Japan (Dr Takahashi); Department of Radiology, School of Medicine, Fukushima Medical University, Fukushima, Japan (Dr Ito)
| | - Hidehiko Takahashi
- Department of Functional Brain Imaging Research, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan (Drs Kubota, Nagashima, Takano, Kodaka, Fujiwara, Moriguchi, Kimura, Higuchi, Takahashi, Ito, and Suhara); Department of Psychiatry, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan (Dr Takano); Department of Psychiatry, Jikei University School of Medicine, Tokyo, Japan (Dr Kodaka); Department of Clinical and Experimental Neuroimaging, Center for Development of Advanced Medicine for Dementia, National Center for Geriatrics and Gerontology, Obu, Japan (Dr Kimura); Department of Neuropsychiatry, Nippon Medical School, Tokyo, Japan (Dr Okubo); Department of Psychiatry, Graduate School of Medicine, Kyoto University, Kyoto, Japan (Dr Takahashi); Department of Radiology, School of Medicine, Fukushima Medical University, Fukushima, Japan (Dr Ito)
| | - Hiroshi Ito
- Department of Functional Brain Imaging Research, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan (Drs Kubota, Nagashima, Takano, Kodaka, Fujiwara, Moriguchi, Kimura, Higuchi, Takahashi, Ito, and Suhara); Department of Psychiatry, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan (Dr Takano); Department of Psychiatry, Jikei University School of Medicine, Tokyo, Japan (Dr Kodaka); Department of Clinical and Experimental Neuroimaging, Center for Development of Advanced Medicine for Dementia, National Center for Geriatrics and Gerontology, Obu, Japan (Dr Kimura); Department of Neuropsychiatry, Nippon Medical School, Tokyo, Japan (Dr Okubo); Department of Psychiatry, Graduate School of Medicine, Kyoto University, Kyoto, Japan (Dr Takahashi); Department of Radiology, School of Medicine, Fukushima Medical University, Fukushima, Japan (Dr Ito)
| | - Tetsuya Suhara
- Department of Functional Brain Imaging Research, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan (Drs Kubota, Nagashima, Takano, Kodaka, Fujiwara, Moriguchi, Kimura, Higuchi, Takahashi, Ito, and Suhara); Department of Psychiatry, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan (Dr Takano); Department of Psychiatry, Jikei University School of Medicine, Tokyo, Japan (Dr Kodaka); Department of Clinical and Experimental Neuroimaging, Center for Development of Advanced Medicine for Dementia, National Center for Geriatrics and Gerontology, Obu, Japan (Dr Kimura); Department of Neuropsychiatry, Nippon Medical School, Tokyo, Japan (Dr Okubo); Department of Psychiatry, Graduate School of Medicine, Kyoto University, Kyoto, Japan (Dr Takahashi); Department of Radiology, School of Medicine, Fukushima Medical University, Fukushima, Japan (Dr Ito).,Correspondence: Tetsuya Suhara, MD, PhD, Department of Functional Brain Imaging Research, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, Chiba 263–8555, Japan ()
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8
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Moritz AE, Free RB, Sibley DR. Advances and challenges in the search for D 2 and D 3 dopamine receptor-selective compounds. Cell Signal 2017; 41:75-81. [PMID: 28716664 DOI: 10.1016/j.cellsig.2017.07.003] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 07/07/2017] [Accepted: 07/10/2017] [Indexed: 12/30/2022]
Abstract
Compounds that target D2-like dopamine receptors (DRs) are currently used as therapeutics for several neuropsychiatric disorders including schizophrenia (antagonists) and Parkinson's disease (agonists). However, as the D2R and D3R subtypes are highly homologous, creating compounds with sufficient subtype-selectivity as well as drug-like properties for therapeutic use has proved challenging. This review summarizes the progress that has been made in developing D2R- or D3R-selective antagonists and agonists, and also describes the experimental conditions that need to be considered when determining the selectivity of a given compound, as apparent selectivity can vary widely depending on assay conditions. Future advances in this field may take advantage of currently available structural data to target alternative secondary binding sites through creating bivalent or bitopic chemical structures. Alternatively, the use of high-throughput screening techniques to identify novel scaffolds that might bind to the D2R or D3R in areas other than the highly conserved orthosteric site, such as allosteric sites, followed by iterative medicinal chemistry will likely lead to exceptionally selective compounds in the future. More selective compounds will provide a better understanding of the normal and pathological functioning of each receptor subtype, as well as offer the potential for improved therapeutics.
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Affiliation(s)
- Amy E Moritz
- Molecular Neuropharmacology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 35 Convent Drive, MSC-3723, Bethesda, MD 20892-3723, United States
| | - R Benjamin Free
- Molecular Neuropharmacology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 35 Convent Drive, MSC-3723, Bethesda, MD 20892-3723, United States
| | - David R Sibley
- Molecular Neuropharmacology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 35 Convent Drive, MSC-3723, Bethesda, MD 20892-3723, United States.
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Meunier CNJ, Chameau P, Fossier PM. Modulation of Synaptic Plasticity in the Cortex Needs to Understand All the Players. Front Synaptic Neurosci 2017; 9:2. [PMID: 28203201 PMCID: PMC5285384 DOI: 10.3389/fnsyn.2017.00002] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 01/13/2017] [Indexed: 12/19/2022] Open
Abstract
The prefrontal cortex (PFC) is involved in cognitive tasks such as working memory, decision making, risk assessment and regulation of attention. These functions performed by the PFC are supposed to rely on rhythmic electrical activity generated by neuronal network oscillations determined by a precise balance between excitation and inhibition balance (E/I balance) resulting from the coordinated activities of recurrent excitation and feedback and feedforward inhibition. Functional alterations in PFC functions have been associated with cognitive deficits in several pathologies such as major depression, anxiety and schizophrenia. These pathological situations are correlated with alterations of different neurotransmitter systems (i.e., serotonin (5-HT), dopamine (DA), acetylcholine…) that result in alterations of the E/I balance. The aim of this review article is to cover the basic aspects of the regulation of the E/I balance as well as to highlight the importance of the complementarity role of several neurotransmitters in the modulation of the plasticity of excitatory and inhibitory synapses. We illustrate our purpose by recent findings that demonstrate that 5-HT and DA cooperate to regulate the plasticity of excitatory and inhibitory synapses targeting layer 5 pyramidal neurons (L5PyNs) of the PFC and to fine tune the E/I balance. Using a method based on the decomposition of the synaptic conductance into its excitatory and inhibitory components, we show that concomitant activation of D1-like receptors (D1Rs) and 5-HT1ARs, through a modulation of NMDA receptors, favors long term potentiation (LTP) of both excitation and inhibition and consequently does not modify the E/I balance. We also demonstrate that activation of D2-receptors requires functional 5-HT1ARs to shift the E-I balance towards more inhibition and to favor long term depression (LTD) of excitatory synapses through the activation of glycogen synthase kinase 3β (GSK3β). This cooperation between different neurotransmitters is particularly relevant in view of pathological situations in which alterations of one neurotransmitter system will also have consequences on the regulation of synaptic efficacy by other neurotransmitters. This opens up new perspectives in the development of therapeutic strategies for the pharmacological treatment of neuronal disorders.
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Affiliation(s)
- Claire N J Meunier
- Institut de Neurosciences Paris-Saclay (NeuroPSI), UMR 91197 CNRS-Université Paris-Saclay Paris, France
| | - Pascal Chameau
- Swammerdam Institute for Life Sciences, Center for NeuroScience, University of Amsterdam Amsterdam, Netherlands
| | - Philippe M Fossier
- Institut de Neurosciences Paris-Saclay (NeuroPSI), UMR 91197 CNRS-Université Paris-Saclay Paris, France
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Sromek AW, Zhang S, Akurathi V, Packard AB, Li W, Alagille D, Morley TJ, Baldwin R, Tamagnan G, Neumeyer JL. Convenient synthesis of 18F-radiolabeled R-(-)-N-n-propyl-2-(3-fluoropropanoxy-11-hydroxynoraporphine. J Labelled Comp Radiopharm 2014; 57:725-9. [PMID: 25400260 DOI: 10.1002/jlcr.3246] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Revised: 10/21/2014] [Accepted: 10/23/2014] [Indexed: 01/17/2023]
Abstract
Aporphines are attractive candidates for imaging D2 receptor function because, as agonists rather than antagonists, they are selective for the receptor in the high affinity state. In contrast, D2 antagonists do not distinguish between the high and low affinity states, and in vitro data suggests that this distinction may be important in studying diseases characterized by D2 dysregulation, such as schizophrenia and Parkinson's disease. Accordingly, MCL-536 (R-(-)-N-n-propyl-2-(3-[(18)F]fluoropropanoxy-11-hydroxynoraporphine) was selected for labeling with (18)F based on in vitro data obtained for the non-radioactive ((19)F) compound. Fluorine-18-labeled MCL-536 was synthesized in 70% radiochemical yield, >99% radiochemical purity, and specific activity of 167 GBq/µmol (4.5 Ci/µmol) using p-toluenesulfonyl (tosyl) both as a novel protecting group for the phenol and a leaving group for the radiofluorination.
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Affiliation(s)
- Anna W Sromek
- Alcohol and Drug Abuse Research Center, McLean Hospital, Harvard Medical School, 115 Mill Street, Belmont, MA, 02478-9106, USA
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van Wieringen JP, Michel MC, Janssen HM, Janssen AG, Elsinga PH, Booij J. Agonist signalling properties of radiotracers used for imaging of dopamine D2/3 receptors. EJNMMI Res 2014; 4:53. [PMID: 25977878 PMCID: PMC4422956 DOI: 10.1186/s13550-014-0053-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Accepted: 09/23/2014] [Indexed: 01/11/2023] Open
Abstract
Background Dopamine D2/3 receptor (D2/3R) agonist radiopharmaceuticals are considered superior to antagonists to detect dopamine release, e.g. induced by amphetamines. Agonists bind preferentially to the high-affinity state of the dopamine D2R, which has been proposed as the reason why agonists are more sensitive to detect dopamine release than antagonist radiopharmaceuticals, but this theory has been challenged. Interestingly, not all agonists similarly activate the classic cyclic adenosine mono phosphate (cAMP) and the ?-arrestin-2 pathway, some stimulate preferentially one of these pathways; a phenomenon called biased agonism. Because these pathways can be affected separately by pathologies or drugs (including dopamine releasers), it is important to know how agonist radiotracers act on these pathways. Therefore, we characterized the intracellular signalling of the well-known D2/3R agonist radiopharmaceuticals NPA and PHNO and of several novel D2/3R agonists. Methods cAMP accumulation and ?-arrestin-2 recruitment were measured on cells expressing human D2R. Results All tested agonists showed (almost) full agonism in both pathways. Conclusions The tested D2/3R agonist radiopharmaceuticals did not exhibit biased agonism in vitro. Consequently, it is likely that drugs (including psychostimulants like amphetamines) and/or pathologies that influence the cAMP and/or the ?-arrestin-2 pathway may influence the binding of these radiopharmaceuticals.
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Affiliation(s)
- Jan-Peter van Wieringen
- Department of Nuclear Medicine, Academic Medical Center, University of Amsterdam, Meibergdreef 9, Amsterdam, 1105, AZ, The Netherlands
| | - Martin C Michel
- Department of Pharmacology, Johannes Gutenberg University, Mainz, Germany
| | | | | | - Philip H Elsinga
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Jan Booij
- Department of Nuclear Medicine, Academic Medical Center, University of Amsterdam, Meibergdreef 9, Amsterdam, 1105, AZ, The Netherlands
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12
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Reinart-Okugbeni R, Vonk A, Uustare A, Gyulai Z, Sipos A, Rinken A. 1-substituted apomorphines as potent dopamine agonists. Bioorg Med Chem 2013; 21:4143-50. [DOI: 10.1016/j.bmc.2013.05.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2013] [Revised: 05/05/2013] [Accepted: 05/08/2013] [Indexed: 01/12/2023]
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13
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Kodaka F, Ito H, Kimura Y, Fujie S, Takano H, Fujiwara H, Sasaki T, Nakayama K, Halldin C, Farde L, Suhara T. Test-retest reproducibility of dopamine D2/3 receptor binding in human brain measured by PET with [11C]MNPA and [11C]raclopride. Eur J Nucl Med Mol Imaging 2012; 40:574-9. [PMID: 23238524 DOI: 10.1007/s00259-012-2312-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Accepted: 11/21/2012] [Indexed: 01/28/2023]
Abstract
PURPOSE Dopamine D receptors (DRs) have two affinity states for endogenous dopamine, referred to as high-affinity state (D ), which has a high affinity for endogenous dopamine, and low-affinity state (D ). The density of D can be measured with (R)-2-CHO-N-n-propylnorapomorphine ([C]MNPA), while total density of D and D (DRs) can be measured with [C]raclopride using positron emission tomography (PET). Thus, the ratio of the binding potential (BP) of [C]MNPA to that of [C]raclopride ([C]MNPA/[C]raclopride) may reflect the proportion of the density of D to that of DRs. In the caudate and putamen, [C]MNPA/[C]raclopride reflects the proportion of the density of D to that of DRs. To evaluate the reliability of the PET paradigm with [C]MNPA and [C]raclopride, we investigated the test-retest reproducibility of non-displaceable BP (BP ) measured with [C]MNPA and of [C]MNPA/[C]raclopride in healthy humans. METHODS Eleven healthy male volunteers underwent two sets of PET studies on separate days that each included [C]MNPA and [C]raclopride scans. BP values in the caudate and putamen were calculated. Test-retest reproducibility of BP of [C]MNPA and [C]MNPA/[C]raclopride was assessed by intra-subject variability (absolute variability) and test-retest reliability (intraclass correlation coefficient: ICC). RESULTS The absolute variability of [C]MNPA BP was 5.30 ± 3.96 % and 12.3 ± 7.95 % and the ICC values of [C]MNPA BP were 0.72 and 0.82 in the caudate and putamen, respectively. The absolute variability of [C]MNPA/[C]raclopride was 6.11 ± 3.68 % and 11.60 ± 5.70 % and the ICC values of [C]MNPA/[C]raclopride were 0.79 and 0.80 in the caudate and putamen, respectively. CONCLUSION In the present preliminary study, the test-retest reproducibility of BP of [C]MNPA and of [C]MNPA/[C]raclopride was reliable in the caudate and putamen.
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Affiliation(s)
- Fumitoshi Kodaka
- Molecular Neuroimaging Program, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba, Japan
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14
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Agonist high- and low-affinity states of dopamine D₂ receptors: methods of detection and clinical implications. Naunyn Schmiedebergs Arch Pharmacol 2012; 386:135-54. [PMID: 23224422 DOI: 10.1007/s00210-012-0817-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Accepted: 11/22/2012] [Indexed: 01/10/2023]
Abstract
Dopamine D(2) receptors, similar to other G-protein-coupled receptors, exist in a high- and low-affinity state for agonists. Based upon a review of the methods for detecting D(2) receptor agonist high-affinity states, we discuss alterations of such states in animal models of disease and the implications of such alterations for their labelling with positron emission tomography (PET) and single-photon emission computed tomography (SPECT) tracers. The classic approach of detecting agonist high-affinity states compares agonist competition for antagonist radioligands, in most cases using [(3)H]-spiperone as the radioligand; alternative approaches and radioligands have been proposed, but their claimed advantages have not been substantiated by other investigators. In view of the advantages and disadvantages of various techniques, we critically have reviewed reported findings on the detection of D(2) receptor agonist high-affinity states in a variety of animal models. These data are compared to the less numerous findings from human in vivo studies based on PET and SPECT tracers; they are interpreted in light of the finding that D(2) receptor agonist high-affinity states under control conditions may differ between rodent and human brain. The potential advantages of agonist ligands in studies of pathophysiology and as diagnostics are being discussed.
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15
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Vauquelin G, Bostoen S, Vanderheyden P, Seeman P. Clozapine, atypical antipsychotics, and the benefits of fast-off D2 dopamine receptor antagonism. Naunyn Schmiedebergs Arch Pharmacol 2012; 385:337-72. [PMID: 22331262 DOI: 10.1007/s00210-012-0734-2] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Accepted: 01/25/2012] [Indexed: 12/20/2022]
Abstract
Drug-receptor interactions are traditionally quantified in terms of affinity and efficacy, but there is increasing awareness that the drug-on-receptor residence time also affects clinical performance. While most interest has hitherto been focused on slow-dissociating drugs, D(2) dopamine receptor antagonists show less extrapyramidal side effects but still have excellent antipsychotic activity when they dissociate swiftly. Fast dissociation of clozapine, the prototype of the "atypical antipsychotics", has been evidenced by distinct radioligand binding approaches both on cell membranes and intact cells. The surmountable nature of clozapine in functional assays with fast-emerging responses like calcium transients is confirmatory. Potential advantages and pitfalls of the hitherto used techniques are discussed, and recommendations are given to obtain more precise dissociation rates for such drugs. Surmountable antagonism is necessary to allow sufficient D(2) receptor stimulation by endogenous dopamine in the striatum. Simulations are presented to find out whether this can be achieved during sub-second bursts in dopamine concentration or rather during much slower, activity-related increases thereof. While the antagonist's dissociation rate is important to distinguish between both mechanisms, this becomes much less so when contemplating time intervals between successive drug intakes, i.e., when pharmacokinetic considerations prevail. Attention is also drawn to the divergent residence times of hydrophobic antagonists like haloperidol when comparing radioligand binding data on cell membranes with those on intact cells and clinical data.
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Affiliation(s)
- Georges Vauquelin
- Department of Molecular and Biochemical Pharmacology, Vrije Universiteit Brussel, Pleinlaan 2, 1050, Brussels, Belgium.
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Measuring Dopamine Synaptic Transmission with Molecular Imaging and Pharmacological Challenges: The State of the Art. MOLECULAR IMAGING IN THE CLINICAL NEUROSCIENCES 2012. [DOI: 10.1007/7657_2012_45] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Seneca N, Finnema SJ, Laszlovszky I, Kiss B, Horváth A, Pásztor G, Kapás M, Gyertyán I, Farkas S, Innis RB, Halldin C, Gulyás B. Occupancy of dopamine D₂ and D₃ and serotonin 5-HT₁A receptors by the novel antipsychotic drug candidate, cariprazine (RGH-188), in monkey brain measured using positron emission tomography. Psychopharmacology (Berl) 2011; 218:579-87. [PMID: 21625907 PMCID: PMC3210913 DOI: 10.1007/s00213-011-2343-z] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Accepted: 05/04/2011] [Indexed: 12/19/2022]
Abstract
RATIONALE Cariprazine is a novel antipsychotic drug candidate that exhibits high selectivity and affinity to dopamine D(3) and D(2) receptors and moderate affinity to serotonin 5-HT(1A) receptors. Targeting receptors other than D(2) may provide a therapeutic benefit for both positive and negative symptoms associated with schizophrenia. Positron emission tomography (PET) can be used as a tool in drug development to assess the in vivo distribution and pharmacological properties of a drug. OBJECTIVES The objective of this study was to determine dopamine D(2)/D(3) and serotonin 5-HT(1A) receptor occupancy in monkey brain after the administration of cariprazine. METHODS We examined three monkeys using the following PET radioligands: [(11)C]MNPA (an agonist at D(2) and D(3) receptors), [(11)C]raclopride (an antagonist at D(2) and D(3) receptors), and [(11)C]WAY-100635 (an antagonist at 5-HT(1A) receptors). During each experimental day, the first PET measurement was a baseline study, the second after a low dose of cariprazine, and the third after the administration of a high dose. RESULTS We found that cariprazine occupied D(2)/D(3) receptors in a dose-dependent and saturable manner, with the lowest dose occupying ~5% of receptors and the highest dose showing more than 90% occupancy. 5-HT(1A) receptor occupancy was considerably lower compared with D(2)/D(3) occupancy at the same doses, with a maximal value of ~30% for the raphe nuclei. CONCLUSIONS We conclude that cariprazine binds preferentially to dopamine D(2)/D(3) rather than to serotonin 5-HT(1A) receptors in monkey brain. These findings can be used to guide the selection of cariprazine dosing in humans.
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Affiliation(s)
- Nicholas Seneca
- Department of Clinical Neuroscience, Psychiatry Section, Karolinska Institutet, Stockholm 171 76, Sweden,Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
| | - Sjoerd J. Finnema
- Department of Clinical Neuroscience, Psychiatry Section, Karolinska Institutet, Stockholm 171 76, Sweden
| | | | - Béla Kiss
- Gedeon Richter Ltd., Budapest 1103, Hungary
| | | | | | | | | | | | - Robert B. Innis
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
| | - Christer Halldin
- Department of Clinical Neuroscience, Psychiatry Section, Karolinska Institutet, Stockholm 171 76, Sweden
| | - Balás Gulyás
- Department of Clinical Neuroscience, Psychiatry Section, Karolinska Institutet, Stockholm 171 76, Sweden
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Seeman P. Dopamine agonist radioligand binds to both D2High and D2Low receptors, explaining why alterations in D2High are not detected in human brain scans. Synapse 2011; 66:88-93. [PMID: 21954082 DOI: 10.1002/syn.20987] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Accepted: 09/06/2011] [Indexed: 01/26/2023]
Abstract
The features of schizophrenia are consistent with increased sensitivity to endogenous dopamine. Animal models of schizophrenia reveal an increase in the in vitro proportion of striatal dopamine D2 receptors in the high-affinity state for dopamine (i.e., D2High), as measured by dopamine/[(3) H]domperidone competition. However, in vivo studies did not reveal the dopamine agonist [(11) C](+)PHNO to be elevated in amphetamine-sensitized rats. Also, no increase was found in the in vivo binding of [(11) C](+)PHNO in schizophrenia patients. This work was done to resolve the contradictory findings. It was found that the in vitro density of rat striatal D2 receptors was 18 pmol/g for [(3) H]raclopride and 12 pmol/g for [(3) H](+)PHNO; most of the latter sites disappeared in the presence of guanine nucleotide. Using 2 nM [(3) H](+)PHNO (K(d) of 0.72 nM at D2) to label D2 receptors in the striata and the human D2 clone, 10 nM to 100 nM dopamine inhibited 10-20% of the [(3) H](+)PHNO bound, representing high-affinity binding of [(3) H](+)PHNO, with the remainder inhibited above 100 nM dopamine, representing low-affinity binding of [(3) H](+)PHNO. It was found that (+)PHNO and (-)NPA dissociated from the D2 clone with half-times of 96 and 600 s, respectively. These rates are slower than the reported sub-second dissociation of the G protein from a receptor, suggesting that these two ligands still occupy the D2Low receptor after the G protein has separated. Thus, the radio-agonist label for (+)PHNO is not selective for dopamine D2High receptors, but also binds to the D2Low state of the dopamine receptor.
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Affiliation(s)
- Philip Seeman
- Department of Pharmacology, University of Toronto, Toronto, Canada M5P 3L6.
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Skinbjerg M, Sibley DR, Javitch JA, Abi-Dargham A. Imaging the high-affinity state of the dopamine D2 receptor in vivo: fact or fiction? Biochem Pharmacol 2011; 83:193-8. [PMID: 21945484 DOI: 10.1016/j.bcp.2011.09.008] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Revised: 09/07/2011] [Accepted: 09/08/2011] [Indexed: 01/27/2023]
Abstract
Positron Emission Tomography (PET) has been used for more than three decades to image and quantify dopamine D2 receptors (D2R) in vivo with antagonist radioligands but in the recent years agonist radioligands have also been employed. In vitro competition studies have demonstrated that agonists bind to both a high and a low-affinity state of the D2Rs, of which the high affinity state reflects receptors that are coupled to G-proteins and the low-affinity state reflects receptors uncoupled from G-proteins. In contrast, antagonists bind with uniform affinity to the total pool of receptors. Results of these studies led to the proposal that D2Rs exist in high and low-affinity states for agonists in vivo and sparked the development and use of agonist radioligands for PET imaging with the primary purpose of measuring the proportion of receptors in the high-affinity (activating) state. Although several lines of research support the presence of high and low-affinity states of D2Rs and their detection by in vivo imaging paradigms, a growing body of controversial data has now called this into question. These include both in vivo and ex vivo studies of anesthesia effects, rodent models with increased proportions of high-affinity state D2Rs as well as the molecular evidence for stable receptor-G-protein complexes. In this commentary we review these data and discuss the evidence for the in vivo existence of D2Rs configured in high and low-affinity states and whether or not the high-affinity state of the D2R can, in fact, be imaged in vivo with agonist radioligands.
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Affiliation(s)
- Mette Skinbjerg
- Department of Psychiatry, Columbia University, New York, NY, USA.
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Seeman P. All roads to schizophrenia lead to dopamine supersensitivity and elevated dopamine D2(high) receptors. CNS Neurosci Ther 2011; 17:118-32. [PMID: 20560996 DOI: 10.1111/j.1755-5949.2010.00162.x] [Citation(s) in RCA: 158] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND The dopamine D2 receptor is the common target for antipsychotics, and the antipsychotic clinical doses correlate with their affinities for this receptor. Antipsychotics quickly enter the brain to occupy 60-80% of brain D2 receptors in patients (the agonist aripiprazole occupies up to 90%), with most clinical improvement occurring within a few days. The D2 receptor can exist in a state of high-affinity (D2(High) ) or in a state of low-affinity for dopamine (D2Low). AIM The present aim is to review why individuals with schizophrenia are generally supersensitive to dopamine-like drugs such as amphetamine or methyphenidate, and whether the D2(High) state is a common basis for dopamine supersensitivity in the animal models of schizophrenia. RESULTS All animal models of schizophrenia reveal elevations in D2(High) receptors. These models include brain lesions, sensitization by drugs (amphetamine, phencyclidine, cocaine, corticosterone), birth injury, social isolation, and gene deletions in pathways for NMDA, dopamine, GABA, acetylcholine, and norepinephrine. CONCLUSIONS These multiple abnormal pathways converge to a final common pathway of dopamine supersensitivity and elevated D2(High) receptors, presumably responsible for psychotic symptoms. Although antipsychotics alleviate psychosis and reverse the elevation of D2(High) receptors, long-term antipsychotics can further enhance dopamine supersensitivity in patients. Therefore, switching from a traditional antipsychotic to an agonist antipsychotic (aripiprazole) can result in psychotic signs and symptoms. Clozapine and quetiapine do not elicit parkinsonism or tardive dyskinesia because they are released from D2 within 12 to 24 h. Traditional antipsychotics remain attached to D2 receptors for days, preventing relapse, but allowing accumulation that can lead to tardive dyskinesia. Future goals include imaging D2(High) receptors and desensitizing them in early-stage psychosis.
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Affiliation(s)
- Philip Seeman
- Departments of Pharmacology and Psychiatry, University of Toronto, 260 Heath Street West, Suite 605, Toronto, Ontario, Canada M5P 3L6.
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Cumming P. Absolute abundances and affinity states of dopamine receptors in mammalian brain: A review. Synapse 2011; 65:892-909. [DOI: 10.1002/syn.20916] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2010] [Accepted: 01/14/2011] [Indexed: 12/14/2022]
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Sromek AW, Si YG, Zhang T, George SR, Seeman P, Neumeyer JL. Synthesis and Evaluation of Fluorinated Aporphines: Potential Positron Emission Tomography Ligands for D2 Receptors. ACS Med Chem Lett 2011; 2:189-194. [PMID: 21666830 DOI: 10.1021/ml1001689] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The 2-fluoroalkoxy substituted catechol-aporphines 6, 8a-f and 11-monohydroxyaporphines 11a-e were synthesized and found to have high in vitro affinity and selectivity for the dopamine D(2) receptors. The catechol aporphines, 8b and 8d, and the monohydroxy aporphines, 11a-d, were identified as candidates for development as potential PET ligands.
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Affiliation(s)
- Anna W. Sromek
- Alcohol & Drug Abuse Research Center, McLean Hospital, Harvard Medical School, 115 Mill Street, Belmont, Massachusetts 02478-9106, United States
| | - Yu-Gui Si
- Alcohol & Drug Abuse Research Center, McLean Hospital, Harvard Medical School, 115 Mill Street, Belmont, Massachusetts 02478-9106, United States
| | - Tangzhi Zhang
- Alcohol & Drug Abuse Research Center, McLean Hospital, Harvard Medical School, 115 Mill Street, Belmont, Massachusetts 02478-9106, United States
| | - Susan R. George
- Department of Pharmacology, University of Toronto, Toronto, Ontario, Canada
| | - Philip Seeman
- Department of Pharmacology, University of Toronto, Toronto, Ontario, Canada
| | - John L. Neumeyer
- Alcohol & Drug Abuse Research Center, McLean Hospital, Harvard Medical School, 115 Mill Street, Belmont, Massachusetts 02478-9106, United States
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Tsukada H, Ohba H, Nishiyama S, Kakiuchi T. Differential effects of stress on [¹¹C]raclopride and [¹¹C]MNPA binding to striatal D₂/D₃ dopamine receptors: a PET study in conscious monkeys. Synapse 2011; 65:84-9. [PMID: 20687105 DOI: 10.1002/syn.20845] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
It has been reported that stress and facilitation of dopamine neuronal system are closely related. In the present study, the effects of stress on the binding of antagonist-based [¹¹C]raclopride and agonist-based (R)-2-CH3O-N-n- propylnorapomorphine ([¹¹C]MNPA) to D₂/D₃ receptors were evaluated in the striatum of conscious monkey brain. The stress state assessed from plasma cortisol level was negatively correlated with [¹¹C]raclopride binding as expected. It was noteworthy that [¹¹C]MNPA binding exhibited a positive correlation with stress state; thus, the animals with higher cortisol levels showed higher binding to D₂/D₃ receptors.
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Affiliation(s)
- Hideo Tsukada
- Central Research Laboratory, Hamamatsu Photonics K.K., Hamakita, Hamamatsu, Shizuoka, Japan.
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Dyck B, Guest K, Sookram C, Basu D, Johnson R, Mishra RK. PAOPA, a potent analogue of Pro-Leu-glycinamide and allosteric modulator of the dopamine D2 receptor, prevents NMDA receptor antagonist (MK-801)-induced deficits in social interaction in the rat: implications for the treatment of negative symptoms in schizophrenia. Schizophr Res 2011; 125:88-92. [PMID: 21036015 PMCID: PMC3010311 DOI: 10.1016/j.schres.2010.09.025] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Revised: 09/28/2010] [Accepted: 09/29/2010] [Indexed: 01/27/2023]
Abstract
The aim of this study was to investigate whether a potent analogue of the endogenous brain peptide l-prolyl-l-leucyl-glycinamide (PLG), (3(R)-[(2(S)-pyrrolidinylcarbonyl)amino]-2-oxo-1-pyrrolidineacetamide (PAOPA), can prevent the induction of social withdrawal caused by sub-chronic treatment with the non-competitive NMDA (N-methyl-l-aspartate) receptor antagonist, MK-801. Results indicate that MK-801 (0.5 mg/kg) significantly decreased social interaction following sub-chronic treatment (7 days). Treatment with PAOPA (1 mg/kg) blocked the effects of MK-801, and increased the amount of time spent in social interaction in comparison to control animals. These results provide evidence for the development of peptidomimetic compounds for the treatment of social withdrawal and related negative symptoms associated with schizophrenia.
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Affiliation(s)
- Bailee Dyck
- Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, ON, Canada
| | - Kelly Guest
- Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, ON, Canada
| | - Christal Sookram
- Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, ON, Canada
| | - Dipannita Basu
- Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, ON, Canada
| | - Rodney Johnson
- Department of Medicinal Chemistry, University of Minnesota, MI, USA
| | - Ram K. Mishra
- Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, ON, Canada
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26
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Skinbjerg M, Seneca N, Liow JS, Hong J, Weinshenker D, Pike VW, Halldin C, Sibley DR, Innis RB. Dopamine beta-hydroxylase-deficient mice have normal densities of D(2) dopamine receptors in the high-affinity state based on in vivo PET imaging and in vitro radioligand binding. Synapse 2010; 64:699-703. [PMID: 20336622 DOI: 10.1002/syn.20781] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
In vitro, D(2) dopamine receptors (DAR) can exist in low- and high-affinity states for agonists and increases of D(2) receptors in high-affinity state have been proposed to underlie DA receptor supersensitivity in vivo. Deletion of the gene for dopamine beta-hydroxylase (DBH) causes mice to become hypersensitive to the effects of psychostimulants, and in vitro radioligand binding results suggest an increased percentage of D(2) receptors in a high-affinity state. To determine whether DBH knockout mice display an increase of high-affinity state D(2) receptors in vivo, we scanned DBH knockout and control mice with the agonist PET radioligand [(11)C]MNPA, which is thought to bind preferentially to the high-affinity state of the D(2) receptor. In addition, we performed in vitro binding experiments on striatal homogenates with [(3)H]methylspiperone to measure B(max) values and the percentages of high- and low-affinity states of the D(2) receptor. We found that the in vivo striatal binding of [(11)C]MNPA was similar in DBH knockout mice and heterozygous controls and the in vitro B(max) values and percentages of D(2) receptors in the high-affinity state, were not significantly different between these two groups. In summary, our results suggest that DBH knockout mice have normal levels of D(2) receptors in the high-affinity state and that additional mechanisms contribute to their behavioral sensitivity to psychostimulants.
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Affiliation(s)
- Mette Skinbjerg
- Molecular Imaging Branch, National Institute of Mental Health, Bethesda, Maryland 20892-2035, USA
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Abstract
The antipsychotic effectiveness of chlorpromazine and haloperidol started a search for their therapeutic targets. The antipsychotic receptor target turned out to be a dopamine receptor, now cloned as the dopamine D2 receptor. The D2 receptor is the common target for antipsychotics. Antipsychotic clinical doses correlate with their affinities for this receptor. Therapeutic doses of antipsychotics occupy 60 to 80% of brain D2 receptors in patients, but aripiprazole occupies up to 90%. While antipsychotics may take up to six hours to occupy D2 receptors, much clinical improvement occurs within a few days. The receptor has high- and low-affinity states. The D2High state is functional for dopamine-like agonists such as aripiprazole. Most individuals with schizophrenia are supersensitive to dopamine. Animal models of psychosis show that a variety of risk factors, genetic and nongenetic, are associated with behavioral supersensitivity to dopamine, reflected in elevated levels of dopamine D2High receptors. Although antipsychotics such as haloperidol alleviate psychosis and reverse the elevation of D2High receptors, long-term use of traditional antipsychotics can further enhance dopamine supersensitivity in patients. Therefore, switching from a traditional antipsychotic to an agonist antipsychotic such as aripiprazole can result in the emergence of psychotic signs and symptoms. Clozapine and quetiapine do not elicit parkinsonism and rarely result in tardive dyskinesia because they are released from D2 within 12 to 24 hours. Traditional antipsychotics remain attached to D2 receptors for days, preventing relapse, but allowing accumulation that can lead to tardive dyskinesia. Future goals include imaging D2High receptors and desensitizing them in early-stage psychosis.
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Affiliation(s)
- Philip Seeman
- Pharmacology Department, Faculty of Medicine, University of Toronto, Canada.
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28
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Xu J, Hassanzadeh B, Chu W, Tu Z, Jones LA, Luedtke RR, Perlmutter JS, Mintun MA, Mach RH. [3H]4-(dimethylamino)-N-(4-(4-(2-methoxyphenyl)piperazin-1-yl) butyl)benzamide: a selective radioligand for dopamine D(3) receptors. II. Quantitative analysis of dopamine D(3) and D(2) receptor density ratio in the caudate-putamen. Synapse 2010; 64:449-59. [PMID: 20175227 DOI: 10.1002/syn.20748] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
4-(Dimethylamino)-N-(4-(4-(2-methoxyphenyl)piperazin-1-yl)butyl)benzamide (WC-10), a N-phenyl piperazine analog, displays high affinity and moderate selectivity for dopamine D(3) receptors versus dopamine D(2) receptors (Chu et al. [2005] Bioorg Med Chem 13:77-87). In this study, WC-10 was radiolabeled with tritium (specific activity = 80 Ci/mmol), and quantitative autoradiography studies were conducted using rhesus monkey and Sprague-Dawley rat brain sections. K(d) values for the binding of [3H]WC-10 to D(3) receptors obtained from quantitative autoradiography with rhesus monkey and rat brain sections are in agreement with K(d) values obtained from cloned human and rat receptors (Xu et al. [2009] Synapse 63:717-728). The D(2) selective antagonist [3H]raclopride binds with 11-fold higher affinity to human HEK D(2L) (K(d) = 1.6 nM) than HEK D(3) (K(d) = 18 nM) receptors; [3H]raclopride binds to rat Sf9 rD(2L) receptors with a K(d) of 6.79 nM, a value that is 4-fold lower than binding to human HEK D(2L) receptors and 2.5-fold higher than binding to rat Sf9 rD(3) receptors. In vitro quantitative autoradiography studies with [3H]WC-10 and [3H]raclopride were conducted on adult rat and rhesus monkey brain sections. A mathematical model for calculating the absolute densities of dopamine D(2) and D(3) receptors based on the in vitro receptor binding data of [3H]WC-10 and [3H]raclopride was developed.
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Affiliation(s)
- Jinbin Xu
- Department of Radiology, Washington University School of Medicine, Saint Louis, Missouri 63110, USA
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29
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Xu J, Chu W, Tu Z, Jones LA, Luedtke RR, Perlmutter JS, Mintun MA, Mach RH. [(3)H]4-(Dimethylamino)-N-[4-(4-(2-methoxyphenyl)piperazin- 1-yl)butyl]benzamide, a selective radioligand for dopamine D(3) receptors. I. In vitro characterization. Synapse 2009; 63:717-28. [PMID: 19425052 DOI: 10.1002/syn.20652] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
4-(Dimethylamino)-N-(4-(4-(2-methoxyphenyl)piperazin-1-yl)butyl)benzamide (WC-10), a N-phenyl piperazine analog, has been shown to have high affinity and selectivity for dopamine D(3) receptors versus dopamine D(2) receptors (Chu et al. [2005] Bioorg Med Chem 13:77-87). In this study, WC-10 was radiolabeled with tritium (specific activity = 80 Ci/mmol) and [(3)H]WC-10 binding to genetically cloned dopamine D(2L) and D(3) receptors was evaluated in vitro. [(3)H]WC-10 binds with a 66-fold higher affinity to human HEK D(3) than HEK D(2L) receptors, with a dissociation constant (K(d)) of 1.2 nM at HEK D(3) receptors. However, [(3)H]WC-10 binds to rat Sf9 rD(3) receptors with a K(d) of 3.9 nM, a value that is 3-fold lower than binding to human HEK D(3) receptors and 40-fold value higher than binding to rat Sf9 rD(2L) receptors. The K(d) values obtained from saturation binding experiments were consistent with the results determined from kinetic (k(on) and k(off)) studies. The pharmacologic profiles of a series of dopaminergic drugs for inhibiting the binding of [(3)H]WC-10 to D(3) receptors was in agreement with previously reported data. In vitro autoradiography studies of rat and monkey brains show that [(3)H]WC-10 labeled D(3) sites in the striatal region.
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Affiliation(s)
- Jinbin Xu
- Department of Radiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Skinbjerg M, Ariano MA, Thorsell A, Heilig M, Halldin C, Innis RB, Sibley DR. Arrestin3 mediates D(2) dopamine receptor internalization. Synapse 2009; 63:621-4. [PMID: 19309759 DOI: 10.1002/syn.20636] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Mette Skinbjerg
- Molecular Neuropharmacology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA
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