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Simola N, Serra M, Marongiu J, Costa G, Morelli M. Increased emissions of 50-kHz ultrasonic vocalizations in hemiparkinsonian rats repeatedly treated with dopaminomimetic drugs: A potential preclinical model for studying the affective properties of dopamine replacement therapy in Parkinson's disease. Prog Neuropsychopharmacol Biol Psychiatry 2021; 108:110184. [PMID: 33242502 DOI: 10.1016/j.pnpbp.2020.110184] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 11/13/2020] [Accepted: 11/18/2020] [Indexed: 12/19/2022]
Abstract
Dopamine replacement therapy used in Parkinson's disease (PD) may induce alterations in the emotional state that can underlie the manifestation of iatrogenic psychiatric-like disturbances. The preclinical investigation of these disturbances is limited, also because few reliable paradigms are available to study the affective properties of dopaminomimetic drugs in parkinsonian animals. To provide a relevant experimental tool in this respect, we evaluated whether dopaminomimetic drugs modified the emission of 50-kHz ultrasonic vocalizations (USVs), a behavioral marker of positive affect, in rats bearing a unilateral lesion with 6-hydroxydopamine in the medial forebrain bundle. Apomorphine (2 or 4 mg/kg, i.p.), L-3,4-dihydroxyphenilalanine (L-DOPA, 6 or 12 mg/kg, i.p.), or pramipexole (2 or 4 mg/kg, i.p.) were administered in a test cage (× 5 administrations) on alternate days. Seven days after treatment discontinuation, rats were re-exposed to the test cage to measure conditioned calling behavior and thereafter received a drug challenge. Hemiparkinsonian rats treated with either apomorphine or L-DOPA, but not pramipexole, markedly vocalized during repeated treatment and after challenge, and showed conditioned calling behavior. Moreover, apomorphine, L-DOPA and pramipexole elicited different patterns of 50-kHz USV emissions and rotational behavior, indicating that calling behavior in hemiparkinsonian rats treated with dopaminomimetic drugs is not a byproduct of motor activation. Taken together, these results suggest that measuring 50-kHz USV emissions may be a relevant experimental tool for studying how dopaminomimetic drugs modify the affective state in parkinsonian rats, with possible implications for the preclinical investigation of iatrogenic psychiatric-like disturbances in PD.
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Affiliation(s)
- Nicola Simola
- Department of Biomedical Sciences, University of Cagliari, Cagliari, Italy; National Institute of Neuroscience (INN), University of Cagliari, Cagliari, Italy.
| | - Marcello Serra
- Department of Biomedical Sciences, University of Cagliari, Cagliari, Italy
| | - Jacopo Marongiu
- Department of Biomedical Sciences, University of Cagliari, Cagliari, Italy
| | - Giulia Costa
- Department of Biomedical Sciences, University of Cagliari, Cagliari, Italy
| | - Micaela Morelli
- Department of Biomedical Sciences, University of Cagliari, Cagliari, Italy; National Institute of Neuroscience (INN), University of Cagliari, Cagliari, Italy; CNR, National Research Council of Italy, Neuroscience Institute, Cagliari, Italy
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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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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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4
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Hayashida M, Miyaoka T, Tsuchie K, Araki T, Izuhara M, Miura S, Kanayama M, Ohtsuki K, Nagahama M, Azis IA, Abdullah RA, Jaya MA, Arauchi R, Hashioka S, Wake R, Tsumori T, Horiguchi J, Oh-Nishi A, Inagaki M. Parvalbumin-positive GABAergic interneurons deficit in the hippocampus in Gunn rats: A possible hyperbilirubinemia-induced animal model of schizophrenia. Heliyon 2019; 5:e02037. [PMID: 31321330 PMCID: PMC6612903 DOI: 10.1016/j.heliyon.2019.e02037] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 05/18/2019] [Accepted: 07/01/2019] [Indexed: 11/25/2022] Open
Abstract
A reduction of GABAergic markers in postmortem tissue is consistently found in schizophrenia. Importantly, these alterations in GABAergic neurons are not global, which means they are more prevalent among distinct subclasses of interneurons, including those that express the calcium binding protein parvalbumin. A decreased expression of parvalbumin in the hippocampus is a consistent observation not only in postmortem human schizophrenia patients, but also in a diverse number of rodent models of the disease. Meanwhile, previously we reported that the congenital hyperbilirubinemia model rats (Gunn rats), which is a mutant of the Wistar strain, showed behavioral abnormalities, for instance, hyperlocomotor activity, deficits of prepulse inhibition, inappropriate social interaction, impaired recognition memory similar with several rodent models of schizophrenia. Several animal studies linked the importance of palvalbumin in relation to abnormal hippocampal activity and schizophrenia-like behavior. Here, we show that parvalbumin positive cell density was significantly lower in the CA1, CA3 and the total hippocampus of Gunn rats (congenital hyperbilirubinemia model rats) compared to Wistar control rats. The correlations between serum UCB levels and loss of PV expression in the hippocampus were also detected. The decreases in the PV-expression in the hippocampus might suggest an association of the behavioral abnormalities as schizophrenia-like behaviors of Gunn rats, compared to the Wistar control rats.
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Affiliation(s)
- Maiko Hayashida
- Department of Psychiatry, Faculty of Medicine, Shimane University, Japan
| | - Tsuyoshi Miyaoka
- Department of Psychiatry, Faculty of Medicine, Shimane University, Japan
| | - Keiko Tsuchie
- Department of Psychiatry, Faculty of Medicine, Shimane University, Japan
| | - Tomoko Araki
- Department of Psychiatry, Faculty of Medicine, Shimane University, Japan
| | - Muneto Izuhara
- Department of Psychiatry, Faculty of Medicine, Shimane University, Japan
| | - Shoko Miura
- Department of Psychiatry, Faculty of Medicine, Shimane University, Japan
| | - Misako Kanayama
- Department of Psychiatry, Faculty of Medicine, Shimane University, Japan
| | - Koji Ohtsuki
- Department of Psychiatry, Faculty of Medicine, Shimane University, Japan
| | - Michiharu Nagahama
- Department of Psychiatry, Faculty of Medicine, Shimane University, Japan
| | | | | | - Muhammad Alim Jaya
- Department of Psychiatry, Faculty of Medicine, Shimane University, Japan
| | - Ryosuke Arauchi
- Department of Psychiatry, Faculty of Medicine, Shimane University, Japan
| | - Sadayuki Hashioka
- Department of Psychiatry, Faculty of Medicine, Shimane University, Japan
| | - Rei Wake
- Department of Psychiatry, Faculty of Medicine, Shimane University, Japan
| | - Toshiko Tsumori
- Department of Nursing, Faculty of Health and Welfare, Prefectural University of Hiroshima, Japan
| | - Jun Horiguchi
- Division of Immune-Neuropsychiatry, Faculty of Medicine, Shimane University, Japan
| | - Arata Oh-Nishi
- Division of Immune-Neuropsychiatry, Faculty of Medicine, Shimane University, Japan
- RESVO Inc., Japan
| | - Masatoshi Inagaki
- Department of Psychiatry, Faculty of Medicine, Shimane University, Japan
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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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6
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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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7
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Mach RH. Small Molecule Receptor Ligands for PET Studies of the Central Nervous System-Focus on G Protein Coupled Receptors. Semin Nucl Med 2017; 47:524-535. [PMID: 28826524 DOI: 10.1053/j.semnuclmed.2017.05.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
G protein-coupled receptors (GPRCs) are a class of proteins that are expressed in high abundance and are responsible for numerous signal transduction pathways in the central nervous system. Consequently, alterations in GPRC function have been associated with a wide variety of neurologic and neuropsychiatric disorders. The development of PET probes for imaging GPRCs has served as a major emphasis of PET radiotracer development and PET imaging studies over the past 30 years. In this review, a basic description of the biology of G proteins and GPRCs is provided. This includes recent evidence of the existence of dimeric and multimeric species of GPRCs that have been termed "receptor mosaics," with an emphasis on the different GPRCs that form complexes with the dopamine D2 receptor. An overview of the different PET radiotracers for imaging the component GPRC within these different multimeric complexes of the D2 receptor is also provided.
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Affiliation(s)
- Robert H Mach
- Department of Radiology, Perelman School Medicine, University of Pennsylvania, Philadelphia, PA.
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8
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Salmas RE, Seeman P, Aksoydan B, Erol I, Kantarcioglu I, Stein M, Yurtsever M, Durdagi S. Analysis of the Glutamate Agonist LY404,039 Binding to Nonstatic Dopamine Receptor D2 Dimer Structures and Consensus Docking. ACS Chem Neurosci 2017; 8:1404-1415. [PMID: 28272861 DOI: 10.1021/acschemneuro.7b00070] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Dopamine receptor D2 (D2R) plays an important role in the human central nervous system and is a focal target of antipsychotic agents. The D2HighR and D2LowR dimeric models previously developed by our group are used to investigate the prediction of binding affinity of the LY404,039 ligand and its binding mechanism within the catalytic domain. The computational data obtained using molecular dynamics simulations fit well with the experimental results. The calculated binding affinities of LY404,039 using MM/PBSA for the D2HighR and D2LowR targets were -12.04 and -9.11 kcal/mol, respectively. The experimental results suggest that LY404,039 binds to D2HighR and D2LowR with binding affinities (Ki) of 8.2 and 1640 nM, respectively. The high binding affinity of LY404,039 in terms of binding to [3H]domperidone was inhibited by the presence of a guanine nucleotide, indicating an agonist action of the drug at D2HighR. The interaction analysis demonstrated that while Asp114 was among the most critical amino acids for D2HighR binding, residues Ser193 and Ser197 were significantly more important within the binding cavity of D2LowR. Molecular modeling analyses are extended to ensemble docking as well as structure-based pharmacophore model (E-pharmacophore) development using the bioactive conformation of LY404,039 at the binding pocket as a template and screening of small-molecule databases with derived pharmacophore models.
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Affiliation(s)
- Ramin Ekhteiari Salmas
- Computational
Biology and Molecular Simulations Laboratory, Department of Biophysics,
School of Medicine, Bahcesehir University, 34349 Istanbul, Turkey
| | - Philip Seeman
- Departments
of Pharmacology and Psychiatry, University of Toronto, 260 Heath
Street West, Unit 605, Toronto, Ontario M5P 3L6, Canada
| | - Busecan Aksoydan
- Computational
Biology and Molecular Simulations Laboratory, Department of Biophysics,
School of Medicine, Bahcesehir University, 34349 Istanbul, Turkey
| | - Ismail Erol
- Computational
Biology and Molecular Simulations Laboratory, Department of Biophysics,
School of Medicine, Bahcesehir University, 34349 Istanbul, Turkey
- Department
of Chemistry, Gebze Technical University, 41400, Kocaeli, Turkey
| | - Isik Kantarcioglu
- Computational
Biology and Molecular Simulations Laboratory, Department of Biophysics,
School of Medicine, Bahcesehir University, 34349 Istanbul, Turkey
| | - Matthias Stein
- Max-Planck Institute for Dynamics of Complex Technical Systems, Molecular Simulations and Design Group, Sandtorstrasse 1, 39106 Magdeburg, Germany
| | - Mine Yurtsever
- Department
of Chemistry, Istanbul Technical University, 34469 Istanbul, Turkey
| | - Serdar Durdagi
- Computational
Biology and Molecular Simulations Laboratory, Department of Biophysics,
School of Medicine, Bahcesehir University, 34349 Istanbul, Turkey
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9
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Ekhteiari Salmas R, Seeman P, Aksoydan B, Stein M, Yurtsever M, Durdagi S. Biological Insights of the Dopaminergic Stabilizer ACR16 at the Binding Pocket of Dopamine D2 Receptor. ACS Chem Neurosci 2017; 8:826-836. [PMID: 28001043 DOI: 10.1021/acschemneuro.6b00396] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The dopamine D2 receptor (D2R) plays an important part in the human central nervous system and it is considered to be a focal target of antipsychotic agents. It is structurally modeled in active and inactive states, in which homodimerization reaction of the D2R monomers is also applied. The ASP2314 (also known as ACR16) ligand, a D2R stabilizer, is used in tests to evaluate how dimerization and conformational changes may alter the ligand binding space and to provide information on alterations in inhibitory mechanisms upon activation. The administration of the D2R agonist ligand ACR16 [3H](+)-4-propyl-3,4,4a,5,6,10b-hexahydro-2H-naphtho[1,2-b][1,4]oxazin-9-ol ((+)PHNO) revealed Ki values of 32 nM for the D2highR and 52 μM for the D2lowR. The calculated binding affinities of ACR16 with post processing molecular dynamics (MD) simulations analyses using MM/PBSA for the monomeric and homodimeric forms of the D2highR were -9.46 and -8.39 kcal/mol, respectively. The data suggests that the dimerization of the D2R leads negative cooperativity for ACR16 binding. The dimerization reaction of the D2highR is energetically favorable by -22.95 kcal/mol. The dimerization reaction structurally and thermodynamically stabilizes the D2highR conformation, which may be due to the intermolecular forces formed between the TM4 of each monomer, and the result strongly demonstrates dimerization essential for activation of the D2R.
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Affiliation(s)
- Ramin Ekhteiari Salmas
- Computational
Biology and Molecular Simulations Laboratory, Department of Biophysics,
School of Medicine, Bahcesehir University, Istanbul, Turkey
| | - Philip Seeman
- Departments
of Pharmacology and Psychiatry, University of Toronto, 260 Heath
Street West, Unit 605, M5P 3L6 Toronto, Ontario Canada
| | - Busecan Aksoydan
- Computational
Biology and Molecular Simulations Laboratory, Department of Biophysics,
School of Medicine, Bahcesehir University, Istanbul, Turkey
| | - Matthias Stein
- Max-Planck
Institute
for Dynamics of Complex Technical Systems, Molecular Simulations and
Design Group, Sandtorstrasse 1, 39106 Magdeburg, Germany
| | - Mine Yurtsever
- Department
of Chemistry, Istanbul Technical University, 34467 Istanbul, Turkey
| | - Serdar Durdagi
- Computational
Biology and Molecular Simulations Laboratory, Department of Biophysics,
School of Medicine, Bahcesehir University, Istanbul, Turkey
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10
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Pintsuk J, Borroto-Escuela DO, Lai TKY, Liu F, Fuxe K. Alterations in ventral and dorsal striatal allosteric A2AR-D2R receptor-receptor interactions after amphetamine challenge: Relevance for schizophrenia. Life Sci 2016; 167:S0024-3205(16)30629-4. [PMID: 27984074 DOI: 10.1016/j.lfs.2016.10.027] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 10/19/2016] [Accepted: 10/28/2016] [Indexed: 12/17/2022]
Abstract
Striatal dopamine D2R homodimerization is increased in the dorsal striatum after acute amphetamine challenge and in the amphetamine-induced sensitized state, a well-known animal model of schizophrenia. Therefore, it was tested if the increase in D2R homoreceptor complexes found after acute amphetamine challenge in the saline or the amphetamine sensitized state leads to changes in the antagonistic adenosine A2AR-D2R interactions in the striatum. [3H]-raclopride binding was performed in membrane preparations from the ventral and dorsal striatum involving competition with the D2R like agonist quinpirole. In the ventral striatum CGS 21680 produced a significant increase of the KiH values (p<0.05) in the amphetamine sensitized group when expressed in percent versus the corresponding values in saline sensitized rats after amphetamine challenge. However, in the dorsal striatum a significant change did not develop in the KiH values when expressed in percent of the corresponding values in saline sensitized rats after amphetamine challenge. In fact, the non-significant change was in the opposite direction towards a reduction of the KiH values. Taken together, a reduced affinity of the high affinity D2 agonist binding site (KiH value) developed in the ventral but not in the dorsal striatum as a result of increased antagonistic allosteric A2AR-D2R interactions in the amphetamine-induced sensitized state versus the saline sensitized state after an acute amphetamine challenge. The selective reappearance of antagonistic A2AR-D2R receptor-receptor interactions in the ventral striatum after amphetamine challenge in the amphetamine sensitized rat may give one possible mechanism for the atypical antipsychotic-like actions of A2AR receptor agonists.
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Affiliation(s)
- Julia Pintsuk
- Department of Neuroscience, Karolinska Institutet, Retzius väg 8, 17177 Stockholm, Sweden; Institute of Biomedicine and Translational Medicine, Department of Physiology, University of Tartu, 19 Ravila Street, 50411 Tartu, Estonia.
| | - Dasiel O Borroto-Escuela
- Department of Neuroscience, Karolinska Institutet, Retzius väg 8, 17177 Stockholm, Sweden; Department of Earth, Life and Environmental Sciences, Section of Physiology, Campus Scientifico Enrico Mattei, via Ca' le Suore 2, I-61029 Urbino, Italy.
| | - Terence K Y Lai
- Campbell Research Institute, Centre for Addiction and Mental Health, University of Toronto, Toronto, Ontario M5T 1R8, Canada.
| | - Fang Liu
- Campbell Research Institute, Centre for Addiction and Mental Health, University of Toronto, Toronto, Ontario M5T 1R8, Canada.
| | - Kjell Fuxe
- Department of Neuroscience, Karolinska Institutet, Retzius väg 8, 17177 Stockholm, Sweden.
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11
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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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12
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Brisch R, Saniotis A, Wolf R, Bielau H, Bernstein HG, Steiner J, Bogerts B, Braun K, Jankowski Z, Kumaratilake J, Henneberg M, Gos T, Henneberg M, Gos T. The role of dopamine in schizophrenia from a neurobiological and evolutionary perspective: old fashioned, but still in vogue. Front Psychiatry 2014; 5:47. [PMID: 24904434 PMCID: PMC4032934 DOI: 10.3389/fpsyt.2014.00047] [Citation(s) in RCA: 184] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Accepted: 04/23/2014] [Indexed: 12/12/2022] Open
Abstract
Dopamine is an inhibitory neurotransmitter involved in the pathology of schizophrenia. The revised dopamine hypothesis states that dopamine abnormalities in the mesolimbic and prefrontal brain regions exist in schizophrenia. However, recent research has indicated that glutamate, GABA, acetylcholine, and serotonin alterations are also involved in the pathology of schizophrenia. This review provides an in-depth analysis of dopamine in animal models of schizophrenia and also focuses on dopamine and cognition. Furthermore, this review provides not only an overview of dopamine receptors and the antipsychotic effects of treatments targeting them but also an outline of dopamine and its interaction with other neurochemical models of schizophrenia. The roles of dopamine in the evolution of the human brain and human mental abilities, which are affected in schizophrenia patients, are also discussed.
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Affiliation(s)
- Ralf Brisch
- Department of Forensic Medicine, Medical University of Gdańsk , Gdańsk , Poland
| | - Arthur Saniotis
- School of Medical Sciences, The University of Adelaide , Adelaide, SA , Australia ; Centre for Evolutionary Medicine, University of Zurich , Zurich , Switzerland
| | - Rainer Wolf
- Department of Psychiatry and Psychotherapy, Ruhr University Bochum , Bochum , Germany
| | - Hendrik Bielau
- Department of Psychiatry, Otto-von-Guericke-University of Magdeburg , Magdeburg , Germany
| | - Hans-Gert Bernstein
- Department of Psychiatry, Otto-von-Guericke-University of Magdeburg , Magdeburg , Germany
| | - Johann Steiner
- Department of Psychiatry, Otto-von-Guericke-University of Magdeburg , Magdeburg , Germany
| | - Bernhard Bogerts
- Department of Psychiatry, Otto-von-Guericke-University of Magdeburg , Magdeburg , Germany
| | - Katharina Braun
- Department of Zoology, Institute of Biology, Otto-von-Guericke-University of Magdeburg , Magdeburg , Germany
| | - Zbigniew Jankowski
- Department of Forensic Medicine, Medical University of Gdańsk , Gdańsk , Poland
| | - Jaliya Kumaratilake
- Biological Anthropology and Comparative Anatomy Research Unit, School of Biomedical Sciences, The University of Adelaide , Adelaide, SA , Australia
| | - Maciej Henneberg
- Biological Anthropology and Comparative Anatomy Research Unit, School of Biomedical Sciences, The University of Adelaide , Adelaide, SA , Australia
| | - Tomasz Gos
- Department of Forensic Medicine, Medical University of Gdańsk , Gdańsk , Poland
| | - Maciej Henneberg
- Biological Anthropology and Comparative Anatomy Research Unit, School of Biomedical Sciences, The University of Adelaide , Adelaide, SA , Australia
| | - Tomasz Gos
- Department of Forensic Medicine, Medical University of Gdańsk , Gdańsk , Poland
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13
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Seeman P. Are dopamine D2 receptors out of control in psychosis? Prog Neuropsychopharmacol Biol Psychiatry 2013; 46:146-52. [PMID: 23880595 DOI: 10.1016/j.pnpbp.2013.07.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Revised: 07/08/2013] [Accepted: 07/08/2013] [Indexed: 01/11/2023]
Abstract
It is known that schizophrenia patients are behaviorally supersensitive to dopamine-like drugs (amphetamine, methylphenidate). There is evidence for an increased release of dopamine, a slight increase of dopamine D2 receptors and an increase of dopamine D2High receptors in schizophrenia, all possibly explaining the clinical supersensitivity to dopamine. The elevation in apparent D2High receptors in vivo in schizophrenia matches the elevation in D2High receptors in many animal models of psychosis. The increased amounts of D2High receptors in psychotic-like behavior in animals may result from a loss of control of D2 by various factors. These factors include the rate of phosphorylation and desensitization of D2 receptors by kinases, the attachment of arrestin to D2 receptors, internalization of D2 receptors, the rate of receptor de-phosphorylation, formation of D2 receptor dimers, and GTP regulation by various GTPases. While at present there are no statistically significant associations of any of these controlling factors and their genes with schizophrenia, investigation of D2High receptors in schizophrenia will require a new radioligand in order to selectively label D2High receptors in vivo in patients. Finally, haloperidol reduces the number of D2High receptors that are elevated by amphetamine, indicating that this therapeutic effect may occur clinically.
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Affiliation(s)
- Philip Seeman
- Department of Pharmacology, University of Toronto, 260 Heath Street, West, unit 605, Toronto, Ontario M5P 3L6, Canada; Department of Psychiatry, University of Toronto, 260 Heath Street, West, unit 605, Toronto, Ontario, M5P 3L6, Canada.
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14
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Boileau I, Payer D, Chugani B, Lobo D, Behzadi A, Rusjan PM, Houle S, Wilson AA, Warsh J, Kish SJ, Zack M. The D2/3 dopamine receptor in pathological gambling: a positron emission tomography study with [11C]-(+)-propyl-hexahydro-naphtho-oxazin and [11C]raclopride. Addiction 2013; 108:953-63. [PMID: 23167711 DOI: 10.1111/add.12066] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Revised: 07/05/2012] [Accepted: 11/09/2012] [Indexed: 11/27/2022]
Abstract
AIMS Pathological gambling (PG) shares diagnostic features with substance use disorder (SUD), but the neurochemical mechanisms underlying PG are poorly understood. Because dopamine (DA), a neurotransmitter implicated in reward and reinforcement, is probably involved, we used positron emission tomography (PET) to test whether PG is associated with abnormalities in D2 and D3 receptor levels, as observed in SUD. DESIGN Case-control study comparing PG to healthy control (HC) subjects. SETTING Academic research imaging centre. PARTICIPANTS Thirteen non-treatment-seeking males meeting DSM-IV criteria for PG, and 12 matched HC (11 of whom completed PET). MEASUREMENTS Two PET scans (one with the D3 receptor preferring agonist [11C]-(+)-propyl-hexahydro-naphtho-oxazin (PHNO) and the other with [11C]raclopride) to assess D(2/3) DA receptor availability, and behavioural measures (self-report questionnaires and slot-machine game) to assess subjective effects and relationships to PET measures. FINDINGS Binding of both radiotracers did not differ between groups in striatum or substantia nigra (SN) (all P > 0.1). Across PG, [11C]-(+)-PHNO binding in SN, where the signal is attributable primarily to D3 receptors, correlated with gambling severity (r = 0.57, P = 0.04) and impulsiveness (r = 0.65, P = 0.03). In HC, [11C]raclopride binding in dorsal striatum correlated inversely with subjective effects of gambling (r = -0.70, P = 0.03) and impulsiveness (r = -0.70, P = 0.03). CONCLUSIONS Unlike with substance use disorder, there appear to be no marked differences in D2 /D3 levels between healthy subjects and pathological gamblers, suggesting that low receptor availability may not be a necessary feature of addiction. However, relationships between [11C]-(+)-PHNO binding and gambling severity/impulsiveness suggests involvement of the D3 receptor in impulsive/compulsive behaviours.
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Affiliation(s)
- Isabelle Boileau
- Addiction Imaging Research Group, Centre for Addiction and Mental Health, Toronto, ON, Canada.
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15
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Beyaert MGR, Daya RP, Dyck BA, Johnson RL, Mishra RK. PAOPA, a potent dopamine D2 receptor allosteric modulator, prevents and reverses behavioral and biochemical abnormalities in an amphetamine-sensitized preclinical animal model of schizophrenia. Eur Neuropsychopharmacol 2013; 23:253-62. [PMID: 22658400 DOI: 10.1016/j.euroneuro.2012.04.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2011] [Revised: 03/13/2012] [Accepted: 04/14/2012] [Indexed: 12/22/2022]
Abstract
Allosteric modulators are emerging as new therapeutics for the treatment of psychiatric illnesses, such as schizophrenia. Conventional antipsychotic drugs are typically dopamine D2 receptor antagonists that compete with endogenous dopamine at the orthosteric site, and block excessive dopamine neurotransmission in the brain. However, they are unable to treat all symptoms of schizophrenia and often cause adverse motor and metabolic side effects. The binding profile of allosteric modulators differs, as they interact with their receptor at a novel binding site and their activity is determined by physiological signaling. In collaboration, our laboratories have synthesized and evaluated over 185 compounds for their allosteric modulatory activity at the dopamine D2 receptor. Of these compounds, PAOPA is among the most potent allosteric modulators, and has been shown to be effective in treating the MK-801 induced preclinical animal model of schizophrenia. The objective of this study was to evaluate PAOPA's ability to prevent and reverse behavioral abnormalities in an amphetamine-sensitized preclinical animal model of schizophrenia. Amphetamine sensitized rats were given PAOPA during sensitization and following sensitization to determine whether PAOPA is able to prevent and reverse behavioral abnormalities. Furthermore, changes in post-mortem dopamine levels were measured by high performance liquid chromatography in various brain regions. The results presented demonstrate that PAOPA is able to prevent and reverse behavioral and biochemical abnormalities in an amphetamine-sensitized animal model of schizophrenia.
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Affiliation(s)
- Michael G R Beyaert
- Department of Psychiatry and Behavioural Neurosciences, McMaster University, Canada
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16
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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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17
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Narendran R, Martinez D, Mason NS, Lopresti BJ, Himes ML, Chen CM, May MA, Price JC, Mathis CA, Frankle WG. Imaging of dopamine D2/3 agonist binding in cocaine dependence: a [11C]NPA positron emission tomography study. Synapse 2012; 65:1344-9. [PMID: 21780185 DOI: 10.1002/syn.20970] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
OBJECTIVE Positron emission tomography (PET) studies performed with [(11) C]raclopride have consistently reported lower binding to D(2/3) receptors and lower amphetamine-induced dopamine (DA) release in cocaine abusers relative to healthy controls. A limitation of these studies that were performed with D(2/3) antagonist radiotracers such as [(11) C]raclopride is the failure to provide information that is specific to D(2/3) receptors configured in a state of high affinity for the agonists (i.e., D(2/3) receptors coupled to G-proteins, D(2/3 HIGH) ). As the endogenous agonist DA binds with preference to D(2/3 HIGH) relative to D(2/3 LOW) receptors (i.e., D(2/3) receptors uncoupled to G-proteins) it is critical to understand the in vivo status of D(2/3 HIGH) receptors in cocaine dependence. Thus, we measured the available fraction of D(2/3) (HIGH) receptors in 10 recently abstinent cocaine abusers (CD) and matched healthy controls (HC) with the D(2/3) antagonist and agonist PET radiotracers [(11) C]raclopride and [(11) C]NPA. METHODS [(11) C]raclopride and [(11) C]NPA binding potential (BP) (BP(ND) ) in the striatum were measured with kinetic analysis using the arterial input function. The available fraction of D(2/3 HIGH) receptors, i.e., % R(HIGH) available = D(2/3 HIGH) /(D(2/3 HIGH) + D(2/3 LOW) ) was then computed as the ratio of [(11) C]NPA BP(ND) /[(11) C]raclopride BP(ND) . RESULTS No differences in striatal [(11) C]NPA BP(ND) (HC = 1.00 ± 0.17; CD = 0.97 ± 0.17, P = 0.67) or available % R(HIGH) (HC = 39% ± 5%; CD = 41% ± 5%, P = 0.50) was observed between cocaine abusers and matched controls. CONCLUSIONS The results of this [(11) C]NPA PET study do not support alterations in D(2/3 HIGH) binding in the striatum in cocaine dependence.
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Affiliation(s)
- Rajesh Narendran
- Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania; Department of Psychiatry, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA.
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18
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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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19
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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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Cariprazine (RGH-188), a potent D3/D2 dopamine receptor partial agonist, binds to dopamine D3 receptors in vivo and shows antipsychotic-like and procognitive effects in rodents. Neurochem Int 2011; 59:925-35. [PMID: 21767587 DOI: 10.1016/j.neuint.2011.07.002] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2011] [Revised: 06/24/2011] [Accepted: 07/01/2011] [Indexed: 11/22/2022]
Abstract
We investigated the in vivo effects of orally administered cariprazine (RGH-188; trans-N-{4-[2-[4-(2,3-dichlorophenyl)-piperazin-1-yl]-ethyl]-cyclohexyl}-N',N'-dimethyl-urea), a D(3)/D(2) dopamine receptor partial agonist with ∼10-fold preference for the D(3) receptor. Oral bioavailability of cariprazine at a dose of 1mg/kg in rats was 52% with peak plasma concentrations of 91ng/mL. Cariprazine 10mg/kg had good blood-brain barrier penetration, with a brain/plasma AUC ratio of 7.6:1. In rats, cariprazine showed dose-dependent in vivo displacement of [(3)H](+)-PHNO, a dopamine D(3) receptor-preferring radiotracer, in the D(3) receptor-rich region of cerebellar lobules 9 and 10. Its potent inhibition of apomorphine-induced climbing in mice (ED(50)=0.27mg/kg) was sustained for 8h. Cariprazine blocked amphetamine-induced hyperactivity (ED(50)=0.12mg/kg) and conditioned avoidance response (CAR) (ED(50)=0.84mg/kg) in rats, and inhibited the locomotor-stimulating effects of the noncompetitive NMDA antagonists MK-801 (ED(50)=0.049mg/kg) and phencyclidine (ED(50)=0.09mg/kg) in mice and rats, respectively. It reduced novelty-induced motor activity of mice (ED(50)=0.11mg/kg) and rats (ED(50)=0.18mg/kg) with a maximal effect of 70% in both species. Cariprazine produced no catalepsy in rats at up to 100-fold dose of its CAR inhibitory ED(50) value. Cariprazine 0.02-0.08mg/kg significantly improved the learning performance of scopolamine-treated rats in a water-labyrinth learning paradigm. Though risperidone, olanzapine, and aripiprazole showed antipsychotic-like activity in many of these assays, they were less active against phencyclidine and more cataleptogenic than cariprazine, and had no significant effect in the learning task. The distinct in vivo profile of cariprazine may be due to its higher affinity and in vivo binding to D(3) receptors versus currently marketed typical and atypical antipsychotics.
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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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Collins GT, Truong YNT, Levant B, Chen J, Wang S, Woods JH. Behavioral sensitization to cocaine in rats: evidence for temporal differences in dopamine D3 and D2 receptor sensitivity. Psychopharmacology (Berl) 2011; 215:609-20. [PMID: 21207013 PMCID: PMC3102773 DOI: 10.1007/s00213-010-2154-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2010] [Accepted: 12/15/2010] [Indexed: 11/27/2022]
Abstract
RATIONALE Cocaine-induced changes in D(2) receptors have been implicated in the expression of sensitized behavioral responses and addiction-like behaviors; however, the influence of D(3) receptors is less clear. OBJECTIVES To characterize the effects of repeated cocaine administration on the sensitivity of rats to D(2)- and D(3)-mediated behaviors, as well as the binding properties of ventral striatal D(2)-like and D(3) receptors. METHODS Pramipexole was used to assess the sensitivity of rats to D(3)/D(2) agonist-induced yawning, hypothermia, and locomotor activity, 24 h, 72 h, 10, 21, and 42 days after repeated cocaine or saline administration. The locomotor effects of cocaine (42 day) and the binding properties of ventral striatal D(2)-like and D(3) receptors (24 h and 42 days) were also evaluated. RESULTS Cocaine-treated rats displayed an enhanced locomotor response to cocaine, as well as a progressive and persistent leftward/upward shift of the ascending limb (72 h-42 day) and leftward shift of the descending limb (42 days) of the pramipexole-induced yawning dose-response curve. Cocaine treatment also decreased B (max) and K (d) for D(2)-like receptors and increased D(3) receptor binding at 42 days. Cocaine treatment did not change pramipexole-induced hypothermia or locomotor activity or yawning induced by cholinergic or serotonergic agonists. CONCLUSIONS These studies suggest that temporal differences exist in the development of cocaine-induced sensitization of D(3) and D(2) receptors, with enhancements of D(3)-mediated behavioral effects observed within 72 h and enhancements of D(2)-mediated behavioral effects apparent 42 days after cocaine. These findings highlight the need to consider changes in D(3) receptor function when thinking about the behavioral plasticity that occurs during abstinence from cocaine use.
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Affiliation(s)
- Gregory T. Collins
- Department of Pharmacology, 1301 MSRB III, 1150 W. Medical Center Drive, University of Michigan Medical School, Ann Arbor, MI 48109-0632, USA
| | - Yen Nhu-Thi Truong
- Department of Pharmacology, 1301 MSRB III, 1150 W. Medical Center Drive, University of Michigan Medical School, Ann Arbor, MI 48109-0632, USA
| | - Beth Levant
- Department of Pharmacology, Toxicology, and Therapeutics, University of Kansas Medical Center, Kansas City, KS 66160, USA
| | - Jianyong Chen
- Departments of Internal Medicine and Medicinal Chemistry, University of Michigan Medical School, Ann Arbor, MI 48109-0934, USA
| | - Shaomeng Wang
- Department of Pharmacology, 1301 MSRB III, 1150 W. Medical Center Drive, University of Michigan Medical School, Ann Arbor, MI 48109-0632, USA. Departments of Internal Medicine and Medicinal Chemistry, University of Michigan Medical School, Ann Arbor, MI 48109-0934, USA
| | - James H. Woods
- Department of Pharmacology, 1301 MSRB III, 1150 W. Medical Center Drive, University of Michigan Medical School, Ann Arbor, MI 48109-0632, USA
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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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Increased in vivo [11C]raclopride binding to brain dopamine receptors in amphetamine-treated rats. Eur J Pharmacol 2011; 654:254-7. [DOI: 10.1016/j.ejphar.2011.01.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2010] [Revised: 12/22/2010] [Accepted: 01/07/2011] [Indexed: 11/18/2022]
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Morelli M, Simola N. Methylxanthines and drug dependence: a focus on interactions with substances of abuse. Handb Exp Pharmacol 2011:483-507. [PMID: 20859810 DOI: 10.1007/978-3-642-13443-2_20] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
This chapter examines the psychostimulant actions of methylxanthines, with a focus on the consequences of their excessive use. Consumption of methylxanthines is pervasive and their use is often associated with that of substances known to produce dependence and to have abuse potential. Therefore, the consequences of this combined use are taken into consideration in order to evaluate whether, and to what extent, methylxanthines could influence dependence on or abuse of other centrally active substances, leading to either amplification or attenuation of their effects. Since the methylxanthine that mostly influences mental processes and readily induces psychostimulation is caffeine, this review mainly focuses on caffeine as a prototype of methylxanthine-produced dependence, examining, at the same time, the risks related to caffeine use.
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Affiliation(s)
- Micaela Morelli
- Department of Toxicology, University of Cagliari, Cagliari, Italy.
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Kiss B, Horti F, Bobok A. In vitro and in vivo comparison of [3H](+)-PHNO and [3H]raclopride binding to rat striatum and lobes 9 and 10 of the cerebellum: A method to distinguish dopamine D3 from D2 receptor sites: A method to distinguish dopamine D3 from D2 receptor sites. Synapse 2010; 65:467-78. [DOI: 10.1002/syn.20867] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2010] [Accepted: 09/07/2010] [Indexed: 12/18/2022]
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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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Ersche KD, Bullmore ET, Craig KJ, Shabbir SS, Abbott S, Müller U, Ooi C, Suckling J, Barnes A, Sahakian BJ, Merlo-Pich EV, Robbins TW. Influence of compulsivity of drug abuse on dopaminergic modulation of attentional bias in stimulant dependence. ARCHIVES OF GENERAL PSYCHIATRY 2010; 67:632-44. [PMID: 20530013 PMCID: PMC3664786 DOI: 10.1001/archgenpsychiatry.2010.60] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
CONTEXT There are no effective pharmacotherapies for stimulant dependence but there are many plausible targets for development of novel therapeutics. We hypothesized that dopamine-related targets are relevant for treatment of stimulant dependence, and there will likely be individual differences in response to dopaminergic challenges. OBJECTIVE To measure behavioral and brain functional markers of drug-related attentional bias in stimulant-dependent individuals studied repeatedly after short-term dosing with dopamine D(2)/D(3) receptor antagonist and agonist challenges. DESIGN Randomized, double-blind, placebo-controlled, parallel-groups, crossover design using pharmacological functional magnetic resonance imaging. SETTING Clinical research unit (GlaxoSmithKline) and local community in Cambridge, England. PARTICIPANTS Stimulant-dependent individuals (n = 18) and healthy volunteers (n = 18). INTERVENTIONS Amisulpride (400 mg), pramipexole dihydrochloride (0.5 mg), or placebo were administered in counterbalanced order at each of 3 repeated testing sessions. MAIN OUTCOME MEASURES Attentional bias for stimulant-related words was measured during functional magnetic resonance imaging by a drug-word Stroop paradigm; trait impulsivity and compulsivity of dependence were assessed at baseline by questionnaire. RESULTS Drug users demonstrated significant attentional bias for drug-related words, which was correlated with greater activation of the left prefrontal and right cerebellar cortex. Attentional bias was greater in people with highly compulsive patterns of stimulant abuse; the effects of dopaminergic challenges on attentional interference and related frontocerebellar activation were different between high- and low-compulsivity subgroups. CONCLUSIONS Greater attentional bias for and greater prefrontal activation by stimulant-related words constitute a candidate neurocognitive marker for dependence. Individual differences in compulsivity of stimulant dependence had significant effects on attentional bias, its brain functional representation, and its short-term modulation by dopaminergic challenges.
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Affiliation(s)
- Karen D Ersche
- University of Cambridge, Behavioural and Clinical Neuroscience Institute, Department of Psychiatry, Cambridge, England.
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Sora I, Li B, Igari M, Hall FS, Ikeda K. Transgenic mice in the study of drug addiction and the effects of psychostimulant drugs. Ann N Y Acad Sci 2010; 1187:218-46. [PMID: 20201856 DOI: 10.1111/j.1749-6632.2009.05276.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The first transgenic models used to study addiction were based upon a priori assumptions about the importance of particular genes in addiction, including the main target molecules of morphine, amphetamine, and cocaine. This consequently emphasized the importance of monoamine transporters, opioid receptors, and monoamine receptors in addiction. Although the effects of opiates were largely eliminated by mu opioid receptor gene knockout, the case for psychostimulants was much more complex. Research using transgenic models supported the idea of a polygenic basis for psychostimulant effects and has associated particular genes with different behavioral consequences of psychostimulants. Phenotypic analysis of transgenic mice, especially gene knockout mice, has been instrumental in identifying the role of specific molecular targets of addictive drugs in their actions. In this article, we summarize studies that have provided insight into the polygenic determination of drug addiction phenotypes in ways that are not possible with other methods, emphasizing research into the effects of psychostimulant drugs in gene knockouts of the monoamine transporters and monoamine receptors.
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Affiliation(s)
- Ichiro Sora
- Department of Biological Psychiatry, Tohoku University Graduate School of Medicine, Sendai, Japan.
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Seeman P, Guan HC. Glutamate agonists for treating schizophrenia have affinity for dopamine D2Highand D3 receptors. Synapse 2009; 63:705-9. [DOI: 10.1002/syn.20673] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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