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Mandeville JB, Weigand-Whittier J, Wey HY, Chen YCI. Amphetamine pretreatment blunts dopamine-induced D2/D3-receptor occupancy by an arrestin-mediated mechanism: A PET study in internalization compromised mice. Neuroimage 2023; 283:120416. [PMID: 37866759 PMCID: PMC10841768 DOI: 10.1016/j.neuroimage.2023.120416] [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] [Received: 08/22/2023] [Revised: 09/29/2023] [Accepted: 10/19/2023] [Indexed: 10/24/2023] Open
Abstract
While all reversible receptor-targeting radioligands for positron emission tomography (PET) can be displaced by competition with an antagonist at the receptor, many radiotracers show limited occupancies using agonists even at high doses. [11C]Raclopride, a D2/D3 receptor radiotracer with rapid kinetics, can identify the direction of changes in the neurotransmitter dopamine, but quantitative interpretation of the relationship between dopamine levels and radiotracer binding has proven elusive. Agonist-induced receptor desensitization and internalization, a homeostatic mechanism to downregulate neurotransmitter-mediated function, can shift radioligand-receptor binding affinity and confound PET interpretations of receptor occupancy. In this study, we compared occupancies induced by amphetamine (AMP) in drug-naive wild-type (WT) and internalization-compromised β-arrestin-2 knockout (KO) mice using a within-scan drug infusion to modulate the kinetics of [11C]raclopride. We additionally performed studies at 3 h following AMP pretreatment, with the hypothesis that receptor internalization should markedly attenuate occupancy on the second challenge, because dopamine cannot access internalized receptors. Without prior AMP treatment, WT mice exhibited somewhat larger binding potential than KO mice but similar AMP-induced occupancy. At 3 h after AMP treatment, WT mice exhibited binding potentials that were 15 % lower than KO mice. At this time point, occupancy was preserved in KO mice but suppressed by 60 % in WT animals, consistent with a model in which most receptors contributing to binding potential in WT animals were not functional. These results demonstrate that arrestin-mediated receptor desensitization and internalization produce large effects in PET [11C]raclopride occupancy studies using agonist challenges.
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Affiliation(s)
- Joseph B Mandeville
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Boston, MA, USA; Harvard Medical School, Boston, MA, USA.
| | - Jonah Weigand-Whittier
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Boston, MA, USA; Department of Bioengineering, University of California, Berkeley, CA, USA
| | - Hsiao-Ying Wey
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Boston, MA, USA; Harvard Medical School, Boston, MA, USA
| | - Yin-Ching I Chen
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Boston, MA, USA; Harvard Medical School, Boston, MA, USA
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2
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Pharmacokinetic neuroimaging to study the dose-related brain kinetics and target engagement of buprenorphine in vivo. Neuropsychopharmacology 2021; 46:1220-1228. [PMID: 33603137 PMCID: PMC8115308 DOI: 10.1038/s41386-021-00976-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 12/18/2020] [Accepted: 01/24/2021] [Indexed: 12/31/2022]
Abstract
A wide range of buprenorphine doses are used for either pain management or maintenance therapy in opioid addiction. The complex in vitro profile of buprenorphine, with affinity for µ-, δ-, and κ-opioid receptors (OR), makes it difficult to predict its dose-related neuropharmacology in vivo. In rats, microPET imaging and pretreatment by OR antagonists were performed to assess the binding of radiolabeled buprenorphine (microdose 11C-buprenorphine) to OR subtypes in vivo (n = 4 per condition). The µ-selective antagonist naloxonazine (10 mg/kg) and the non-selective OR antagonist naloxone (1 mg/kg) blocked the binding of 11C-buprenorphine, while pretreatment by the δ-selective (naltrindole, 3 mg/kg) or the κ-selective antagonist (norbinaltorphimine, 10 mg/kg) did not. In four macaques, PET imaging and kinetic modeling enabled description of the regional brain kinetics of 11C-buprenorphine, co-injected with increasing doses of unlabeled buprenorphine. No saturation of the brain penetration of buprenorphine was observed for doses up to 0.11 mg/kg. Regional differences in buprenorphine-associated receptor occupancy were observed. Analgesic doses of buprenorphine (0.003 and 0.006 mg/kg), respectively, occupied 20% and 49% of receptors in the thalamus while saturating the low but significant binding observed in cerebellum and occipital cortex. Occupancy >90% was achieved in most brain regions with plasma concentrations >7 µg/L. PET data obtained after co-injection of an analgesic dose of buprenorphine (0.003 mg/kg) predicted the binding potential of microdose 11C-buprenorphine. This strategy could be further combined with pharmacodynamic exploration or pharmacological MRI to investigate the neuropharmacokinetics and neuroreceptor correlate, at least at µ-OR, of the acute effects of buprenorphine in humans.
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3
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Butler SH. Some controversies related to questionable clinical uses of methadone for chronic non-cancer pain and in palliative care. Scand J Pain 2021; 21:421-425. [PMID: 33725755 DOI: 10.1515/sjpain-2020-0178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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4
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Ott J, Spilhaug MM, Maschauer S, Rafique W, Jakobsson JE, Hartvig K, Hübner H, Gmeiner P, Prante O, Riss PJ. Pharmacological Characterization of Low-to-Moderate Affinity Opioid Receptor Agonists and Brain Imaging with 18F-Labeled Derivatives in Rats. J Med Chem 2020; 63:9484-9499. [PMID: 32787100 PMCID: PMC7497404 DOI: 10.1021/acs.jmedchem.0c00683] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The 3,4-dichloro-N-(1-(dimethylamino)cyclohexyl)methyl benzamide scaffold was studied as a template for 18F-positron emission tomography (18F-PET) radiotracer development emphasizing sensitivity to changes in opioid receptor (OR) occupancy over high affinity. Agonist potency, binding affinity, and relevant pharmacological parameters of 15 candidates were investigated. Two promising compounds 3b and 3e with μ-OR (MOR) selective agonist activity in the moderate range (EC50 = 1-100 nM) were subjected to 18F-fluorination, autoradiography, and small-animal PET imaging. Radioligands [18F]3b and [18F]3e were obtained in activity yields of 21 ± 5 and 23 ± 4% and molar activities of 25-40 and 200-300 GBq/μmol, respectively. Displaceable binding matching MOR distribution in the brain was confirmed by imaging. Radioligands showed a rapid pharmacokinetic profile; however, metabolite-corrected, blood-based modeling was required for data analysis. Observed BPND was low, although treatment with naloxone leads to a marked decrease in specific binding, confirming the discovery of a new template for 18F-labeled OR-agonist PET ligands.
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Affiliation(s)
- Julian Ott
- Department of Nuclear Medicine, Molecular Imaging and Radiochemistry, Translational Research Center, Friedrich Alexander University Erlangen-Nürnberg (FAU), Schwabachanlage 12, D-91054 Erlangen, Germany
| | - Mona M Spilhaug
- Realomics SRI, Kjemisk Institutt, Universitetet i Oslo, N-0376 Oslo, Norway
| | - Simone Maschauer
- Department of Nuclear Medicine, Molecular Imaging and Radiochemistry, Translational Research Center, Friedrich Alexander University Erlangen-Nürnberg (FAU), Schwabachanlage 12, D-91054 Erlangen, Germany
| | - Waqas Rafique
- Realomics SRI, Kjemisk Institutt, Universitetet i Oslo, N-0376 Oslo, Norway
| | - Jimmy E Jakobsson
- Realomics SRI, Kjemisk Institutt, Universitetet i Oslo, N-0376 Oslo, Norway
| | - Karoline Hartvig
- Realomics SRI, Kjemisk Institutt, Universitetet i Oslo, N-0376 Oslo, Norway
| | - Harald Hübner
- Department of Chemistry and Pharmacy, Medicinal Chemistry, Emil Fischer Center, Friedrich Alexander University Erlangen-Nürnberg (FAU), Nikolaus-Fiebiger-Straße 10, D-91058 Erlangen, Germany
| | - Peter Gmeiner
- Department of Chemistry and Pharmacy, Medicinal Chemistry, Emil Fischer Center, Friedrich Alexander University Erlangen-Nürnberg (FAU), Nikolaus-Fiebiger-Straße 10, D-91058 Erlangen, Germany
| | - Olaf Prante
- Department of Nuclear Medicine, Molecular Imaging and Radiochemistry, Translational Research Center, Friedrich Alexander University Erlangen-Nürnberg (FAU), Schwabachanlage 12, D-91054 Erlangen, Germany
| | - Patrick J Riss
- Realomics SRI, Kjemisk Institutt, Universitetet i Oslo, N-0376 Oslo, Norway.,Division of Clinical Neuroscience, Neuroscience Research Unit, OUS-UllevÅl, N-0450 Oslo, Norway
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5
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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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Takai N, Miyajima N, Tonomura M, Abe K. Relationship between receptor occupancy and the antinociceptive effect of mu opioid receptor agonists in male rats. Brain Res 2017; 1680:105-109. [PMID: 29269051 DOI: 10.1016/j.brainres.2017.12.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Revised: 11/13/2017] [Accepted: 12/12/2017] [Indexed: 11/24/2022]
Abstract
The analgesic mechanisms of mu opioid receptor (MOR) agonists, including receptor occupancy at the site of action, are not completely understood. The aims of the present study were to evaluate: (i) receptor occupancy in the rat brain after administration of MOR agonists; (ii) the relationship between occupancy and the antinociceptive effect. Morphine (2 or 4 mg/kg) or oxycodone (1 or 3 mg/kg) was subcutaneously administered to rats. The antinociceptive effect of these drugs was measured by the hot-plate test. MOR occupancy in the thalamus was assessed by conducting an ex vivo receptor binding assay using [3H] [D-Ala2, N-MePhe4, Gly-ol]-enkephalin, followed by autoradiographic analysis. Both drugs produced antinociception in a dose-dependent manner, and these effects disappeared after the time point at which the maximal effect was elicited. Thalamic MOR occupancy was observed in a dose-dependent manner at the time point at which maximal antinociception was elicited, and relatively low occupancy was observed when the antinociceptive effect was decreasing. Good correlation between thalamic MOR occupancy and the antinociceptive effect was observed. These findings provide direct evidence for the receptor occupancy of MOR agonists at the site of action and its relationship with the analgesic effect.
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Affiliation(s)
- Nozomi Takai
- Biomarker R&D Department, Shionogi & Co., Ltd., Osaka, Japan.
| | | | - Misato Tonomura
- Biomarker R&D Department, Shionogi & Co., Ltd., Osaka, Japan.
| | - Kohji Abe
- Biomarker R&D Department, Shionogi & Co., Ltd., Osaka, Japan.
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7
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Rafique W, Khanapur S, Spilhaug MM, Riss PJ. Reaching out for Sensitive Evaluation of the Mu Opioid Receptor in Vivo: Positron Emission Tomography Imaging of the Agonist [ 11C]AH7921. ACS Chem Neurosci 2017; 8:1847-1852. [PMID: 28590714 DOI: 10.1021/acschemneuro.7b00075] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Imaging of the mu opioid receptor (MOR) availability with positron emission tomography (PET) is a pertinent challenge in Neuroscience. Both, regulation of receptor expression and occupancy by endogeneous opioids play into cognitive and behavioral phenotypes of healthy function and disease. Receptor expression in the active and inactive states can be measured using high affinity radioagonist and radioantagonist PET tracers, respectively. Occupancy assessment requires radioligands showing competitive and reversible binding with moderate affinity to the MOR, which may lead to physical extinction of the receptor specific signal in vivo. We investigated a moderately potent, selective MOR agonist in rat to test if a radiotracer design paradigm tailored to competition with endogeneous opioids leads to viable imaging results. The benzamide 3,4-dichlorobenzenecarboxylic acid (dimethylamino)cyclohexyl)methyl amide (AH-7921, 1) was synthesized and characterized in rat brain using autoradiography and positron emission tomography. Compound 1 was found to activate with low nanomolar potency the MOR and to a lesser extent KOR as a full agonist. Concentration dependent binding studies with agonist and antagonist radioligands were conducted to assess competition behavior and obtain inhibition constants. Kinetic analysis of 3,4-dichlorobenzene[11C]carboxylic acid (dimethylamino)cyclohexyl)methyl amide binding in rat brain resulted in low but reproducible binding potential in the thalamus (0.8 ± 0.1). A radioactive metabolite was detected in brain (17%, after 15 min). Nonetheless, we conclude that quantitative imaging of MOR availability is possible when using a moderate affinity radiotracer.
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Affiliation(s)
- Waqas Rafique
- realomics
SFI, Kjemisk Institutt, Universitetet i Oslo, Sem Sælands vei 26, Kjemibygningen, 0371 Oslo, Norway
| | - Shivashankar Khanapur
- realomics
SFI, Kjemisk Institutt, Universitetet i Oslo, Sem Sælands vei 26, Kjemibygningen, 0371 Oslo, Norway
- Radboud Translational Medicine BV, Geert Grooteplein
21, Postbus 9101, 6500HB Nijmegen, Netherland
| | - Mona M. Spilhaug
- realomics
SFI, Kjemisk Institutt, Universitetet i Oslo, Sem Sælands vei 26, Kjemibygningen, 0371 Oslo, Norway
| | - Patrick J. Riss
- realomics
SFI, Kjemisk Institutt, Universitetet i Oslo, Sem Sælands vei 26, Kjemibygningen, 0371 Oslo, Norway
- Klinik
for Kirurgi og Nevrofag, Oslo Universitets Sykehus HF−Rikshospitalet, Postboks
4950 Nydalen, 0424 Oslo, Norway
- Norsk Medisinsk Syklotronsenter AS, Gaustad, Postboks 4950 Nydalen, 0424 Oslo, Norway
- Radboud Translational Medicine BV, Geert Grooteplein
21, Postbus 9101, 6500HB Nijmegen, Netherland
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8
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Jones KA, Menniti FS, Sivarao DV. Translational psychiatry-light at the end of the tunnel. Ann N Y Acad Sci 2015; 1344:1-11. [DOI: 10.1111/nyas.12725] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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9
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Quelch DR, Katsouri L, Nutt DJ, Parker CA, Tyacke RJ. Imaging endogenous opioid peptide release with [11C]carfentanil and [3H]diprenorphine: influence of agonist-induced internalization. J Cereb Blood Flow Metab 2014; 34:1604-12. [PMID: 25005876 PMCID: PMC4269718 DOI: 10.1038/jcbfm.2014.117] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Accepted: 06/11/2014] [Indexed: 01/23/2023]
Abstract
Understanding the cellular processes underpinning the changes in binding observed during positron emission tomography neurotransmitter release studies may aid translation of these methodologies to other neurotransmitter systems. We compared the sensitivities of opioid receptor radioligands, carfentanil, and diprenorphine, to amphetamine-induced endogenous opioid peptide (EOP) release and methadone administration in the rat. We also investigated whether agonist-induced internalization was involved in reductions in observed binding using subcellular fractionation and confocal microscopy. After radioligand administration, significant reductions in [(11)C]carfentanil, but not [(3)H]diprenorphine, uptake were observed after methadone and amphetamine pretreatment. Subcellular fractionation and in vitro radioligand binding studies showed that amphetamine pretreatment only decreased total [(11)C]carfentanil binding. In vitro saturation binding studies conducted in buffers representative of the internalization pathway suggested that μ-receptors are significantly less able to bind the radioligands in endosomal compared with extracellular compartments. Finally, a significant increase in μ-receptor-early endosome co-localization in the hypothalamus was observed after amphetamine and methadone treatment using double-labeling confocal microscopy, with no changes in δ- or κ-receptor co-localization. These data indicate carfentanil may be superior to diprenorphine when imaging EOP release in vivo, and that alterations in the ability to bind internalized receptors may be a predictor of ligand sensitivity to endogenous neurotransmitter release.
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Affiliation(s)
- Darren R Quelch
- Centre for Neuropsychopharmacology, Division of Brain Sciences, Imperial College London, London, UK
| | - Loukia Katsouri
- Centre for Neuroinflammation and Neurodegeneration, Division of Brain Sciences, Imperial College London, Hammersmith Hospital, London, UK
| | - David J Nutt
- Centre for Neuropsychopharmacology, Division of Brain Sciences, Imperial College London, London, UK
| | - Christine A Parker
- 1] Centre for Neuropsychopharmacology, Division of Brain Sciences, Imperial College London, London, UK [2] Global Imaging Unit, GlaxoSmithKline, Stevenage, UK
| | - Robin J Tyacke
- Centre for Neuropsychopharmacology, Division of Brain Sciences, Imperial College London, London, UK
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10
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Schoultz BW, Hjørnevik T, Reed BJ, Marton J, Coello CS, Willoch F, Henriksen G. Synthesis and evaluation of three structurally related ¹⁸F-labeled orvinols of different intrinsic activities: 6-O-[¹⁸F]fluoroethyl-diprenorphine ([¹⁸F]FDPN), 6-O-[¹⁸F]fluoroethyl-buprenorphine ([¹⁸F]FBPN), and 6-O-[¹⁸F]fluoroethyl-phenethyl-orvinol ([¹⁸F]FPEO). J Med Chem 2014; 57:5464-9. [PMID: 24933507 DOI: 10.1021/jm500503k] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We report the synthesis and biological evaluation of a triplet of 6-O-(18)F-fluoroethylated derivatives of structurally related orvinols that span across the full range of intrinsic activities, the antagonist diprenorphine, the partial agonist buprenorphine, and the full agonist phenethyl-orvinol. [(18)F]fluoroethyl-diprenorphine, [(18)F]fluoroethyl-buprenorphine, and [(18)F]fluoroethyl-phenethyl-orvinol were prepared in high yields and quality from their 6-O-desmethyl-precursors. The results indicate suitable properties of the three 6-O-(18)F-fluoroethylated derivatives as functional analogues to the native carbon-11 labeled versions with similar pharmacological properties.
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Affiliation(s)
- Bent W Schoultz
- Department of Chemistry, University of Oslo , P.O. Box 1033, Blindern, N-0315 Oslo, Norway
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11
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Fairclough M, Prenant C, Brown G, McMahon A, Lowe J, Jones A. The automated radiosynthesis and purification of the opioid receptor antagonist, [6-O-methyl-11C]diprenorphine on the GE TRACERlab FXFE radiochemistry module. J Labelled Comp Radiopharm 2014; 57:388-96. [PMID: 24692062 DOI: 10.1002/jlcr.3194] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Revised: 12/23/2013] [Accepted: 01/29/2014] [Indexed: 11/10/2022]
Abstract
[6-O-Methyl-(11)C]diprenorphine ([(11)C]diprenorphine) is a positron emission tomography ligand used to probe the endogenous opioid system in vivo. Diprenorphine acts as an antagonist at all of the opioid receptor subtypes, that is, μ (mu), κ (kappa) and δ (delta). The radiosynthesis of [(11)C]diprenorphine using [(11)C]methyl iodide produced via the 'wet' method on a home-built automated radiosynthesis set-up has been described previously. Here, we describe a modified synthetic method to [(11)C]diprenorphine performed using [(11)C]methyl iodide produced via the gas phase method on a GE TRACERlab FXFE radiochemistry module. Also described is the use of [(11)C]methyl triflate as the carbon-11 methylating agent for the [(11)C]diprenorphine syntheses. [(11)C]Diprenorphine was produced to good manufacturing practice standards for use in a clinical setting. In comparison to previously reported [(11)C]diprenorphine radiosyntheisis, the method described herein gives a higher specific activity product which is advantageous for receptor occupancy studies. The radiochemical purity of [(11)C]diprenorphine is similar to what has been reported previously, although the radiochemical yield produced in the method described herein is reduced, an issue that is inherent in the gas phase radiosynthesis of [(11)C]methyl iodide. The yields of [(11)C]diprenorphine are nonetheless sufficient for clinical research applications. Other advantages of the method described herein are an improvement to both reproducibility and reliability of the production as well as simplification of the purification and formulation steps. We suggest that our automated radiochemistry route to [(11)C]diprenorphine should be the method of choice for routine [(11)C]diprenorphine productions for positron emission tomography studies, and the production process could easily be transferred to other radiochemistry modules such as the TRACERlab FX C pro.
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Affiliation(s)
- Michael Fairclough
- Wolfson Molecular Imaging Centre, The University of Manchester, 27 Palatine Road, Manchester, M20 3LJ, UK
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12
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Riss PJ, Hong YT, Marton J, Caprioli D, Williamson DJ, Ferrari V, Saigal N, Roth BL, Henriksen G, Fryer TD, Dalley JW, Aigbirhio FI. Synthesis and Evaluation of 18F-FE-PEO in Rodents: An 18F-Labeled Full Agonist for Opioid Receptor Imaging. J Nucl Med 2013; 54:299-305. [DOI: 10.2967/jnumed.112.108688] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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13
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Blum K, Chen TJH, Bailey J, Bowirrat A, Femino J, Chen ALC, Simpatico T, Morse S, Giordano J, Damle U, Kerner M, Braverman ER, Fornari F, Downs BW, Rector C, Barh D, Oscar-Berman M. Can the chronic administration of the combination of buprenorphine and naloxone block dopaminergic activity causing anti-reward and relapse potential? Mol Neurobiol 2011; 44:250-68. [PMID: 21948099 DOI: 10.1007/s12035-011-8206-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2011] [Accepted: 09/07/2011] [Indexed: 01/21/2023]
Abstract
Opiate addiction is associated with many adverse health and social harms, fatal overdose, infectious disease transmission, elevated health care costs, public disorder, and crime. Although community-based addiction treatment programs continue to reduce the harms of opiate addiction with narcotic substitution therapy such as methadone maintenance, there remains a need to find a substance that not only blocks opiate-type receptors (mu, delta, etc.) but also provides agonistic activity; hence, the impetus arose for the development of a combination of narcotic antagonism and mu receptor agonist therapy. After three decades of extensive research, the federal Drug Abuse Treatment Act 2000 (DATA) opened a window of opportunity for patients with addiction disorders by providing increased access to options for treatment. DATA allows physicians who complete a brief specialty-training course to become certified to prescribe buprenorphine and buprenorphine/naloxone (Subutex, Suboxone) for treatment of patients with opioid dependence. Clinical studies indicate that buprenorphine maintenance is as effective as methadone maintenance in retaining patients in substance abuse treatment and in reducing illicit opioid use. With that stated, we must consider the long-term benefits or potential toxicity attributed to Subutex or Suboxone. We describe a mechanism whereby chronic blockade of opiate receptors, in spite of only partial opiate agonist action, may ultimately block dopaminergic activity causing anti-reward and relapse potential. While the direct comparison is not as yet available, toxicity to buprenorphine can be found in the scientific literature. In considering our cautionary note in this commentary, we are cognizant that, to date, this is what we have available, and until such a time when the real magic bullet is discovered, we will have to endure. However, more than anything else this commentary should at least encourage the development of thoughtful new strategies to target the specific brain regions responsible for relapse prevention.
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Affiliation(s)
- Kenneth Blum
- Department of Psychiatry and McKnight Brain Institute, University of Florida College of Medicine, Gainesville, FL 32610, USA.
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14
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Cumming P, Caprioli D, Dalley JW. What have positron emission tomography and 'Zippy' told us about the neuropharmacology of drug addiction? Br J Pharmacol 2011; 163:1586-604. [PMID: 20846139 PMCID: PMC3166689 DOI: 10.1111/j.1476-5381.2010.01036.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2010] [Revised: 08/09/2010] [Accepted: 08/31/2010] [Indexed: 11/27/2022] Open
Abstract
Translational molecular imaging with positron emission tomography (PET) and allied technologies offer unrivalled applications in the discovery of biomarkers and aetiological mechanisms relevant to human disease. Foremost among clinical PET findings during the past two decades of addiction research is the seminal discovery of reduced dopamine D(2/3) receptor expression in the striatum of drug addicts, which could indicate a predisposing factor and/or compensatory reaction to the chronic abuse of stimulant drugs. In parallel, recent years have witnessed significant improvements in the performance of small animal tomographs (microPET) and a refinement of animal models of addiction based on clinically relevant diagnostic criteria. This review surveys the utility of PET in the elucidation of neuropharmacological mechanisms underlying drug addiction. It considers the consequences of chronic drug exposure on regional brain metabolism and neurotransmitter function and identifies those areas where further research is needed, especially concerning the implementation of PET tracers targeting neurotransmitter systems other than dopamine, which increasingly have been implicated in the pathophysiology of drug addiction. In addition, this review considers the causal effects of behavioural traits such as impulsivity and novelty/sensation-seeking on the emergence of compulsive drug-taking. Previous research indicates that spontaneously high-impulsive rats--as exemplified by 'Zippy'--are pre-disposed to escalate intravenous cocaine self-administration, and subsequently to develop compulsive drug taking tendencies that endure despite concurrent adverse consequences of such behaviour, just as in human addiction. The discovery using microPET of pre-existing differences in dopamine D(2/3) receptor expression in the striatum of high-impulsive rats suggests a neural endophenotype that may likewise pre-dispose to stimulant addiction in humans.
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Affiliation(s)
- Paul Cumming
- Department of Nuclear Medicine, Ludwig-Maximilian's University, Munich, Germany
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Tournier N, Valette H, Peyronneau MA, Saba W, Goutal S, Kuhnast B, Dollé F, Scherrmann JM, Cisternino S, Bottlaender M. Transport of Selected PET Radiotracers by Human P-Glycoprotein (ABCB1) and Breast Cancer Resistance Protein (ABCG2): An In Vitro Screening. J Nucl Med 2011; 52:415-23. [DOI: 10.2967/jnumed.110.079608] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
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Evaluation of the kappa-opioid receptor-selective tracer [11C]GR103545 in awake rhesus macaques. Eur J Nucl Med Mol Imaging 2010; 37:1174-80. [DOI: 10.1007/s00259-010-1384-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2009] [Accepted: 01/05/2010] [Indexed: 10/19/2022]
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Marton J, Schoultz BW, Hjørnevik T, Drzezga A, Yousefi BH, Wester HJ, Willoch F, Henriksen G. Synthesis and evaluation of a full-agonist orvinol for PET-imaging of opioid receptors: [11C]PEO. J Med Chem 2009; 52:5586-9. [PMID: 19694469 DOI: 10.1021/jm900892x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Antagonist radiotracers have shown only a low sensitivity for detecting competition from high-efficacy agonists at opioid receptors (ORs) in vivo. We report that [(11)C]PEO binds with high affinity to mu and kappa-opioid receptors, is a full agonist, and concentrates in brain regions of rats with a high density of the mu-OR after intravenous injection. Blocking studies with mu and kappa-OR selective compounds demonstrated that the binding of [(11)C]PEO is saturable and selective to the mu-OR in rat brain.
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Affiliation(s)
- János Marton
- ABX Advanced Biochemical Compounds, Biomedizinische Forschungsreagenzien GmbH, Radeberg, Germany
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Abstract
This paper is the thirtieth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2007 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia; stress and social status; tolerance and dependence; learning and memory; eating and drinking; alcohol and drugs of abuse; sexual activity and hormones, pregnancy, development and endocrinology; mental illness and mood; seizures and neurologic disorders; electrical-related activity and neurophysiology; general activity and locomotion; gastrointestinal, renal and hepatic functions; cardiovascular responses; respiration and thermoregulation; and immunological responses.
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Affiliation(s)
- Richard J Bodnar
- Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, 65-30 Kissena Blvd.,Flushing, NY 11367, United States.
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Nutt D, Lingford-Hughes A. Addiction: the clinical interface. Br J Pharmacol 2008; 154:397-405. [PMID: 18414399 PMCID: PMC2442452 DOI: 10.1038/bjp.2008.101] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2007] [Revised: 02/29/2008] [Accepted: 03/03/2008] [Indexed: 11/09/2022] Open
Abstract
This review gives an overview of what we see as the key issues in the human pharmacology of drugs of addiction. We review evidence of efficacy and mechanisms by which treatments act and point out areas where further work is needed. The role of agonist, partial agonist and antagonist treatments for opioid addiction is detailed and current issues relating to the mechanisms of actions at the receptor level and how to improve on compliance are discussed. The role of the brain dopamine and GABA-A systems in drug dependence is considered in relation to the growing pharmacology of these receptor systems, and the current status of novel preclinical targets reviewed. In addition, the different roles of dynamic and kinetic factors in both addiction and its treatment are discussed in relation to the underlying neuropharmacology of the disorders as defined from human and preclinical studies. Finally, some pointers to future research and especially to drug development by pharma are elaborated.
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Affiliation(s)
- D Nutt
- Psychopharmacology Unit, University of Bristol, Bristol, UK.
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Boecker H, Sprenger T, Spilker ME, Henriksen G, Koppenhoefer M, Wagner KJ, Valet M, Berthele A, Tolle TR. The runner's high: opioidergic mechanisms in the human brain. Cereb Cortex 2008; 18:2523-31. [PMID: 18296435 DOI: 10.1093/cercor/bhn013] [Citation(s) in RCA: 288] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The runner's high describes a euphoric state resulting from long-distance running. The cerebral neurochemical correlates of exercise-induced mood changes have been barely investigated so far. We aimed to unravel the opioidergic mechanisms of the runner's high in the human brain and to identify the relationship to perceived euphoria. We performed a positron emission tomography "ligand activation" study with the nonselective opioidergic ligand 6-O-(2-[(18)F]fluoroethyl)-6-O-desmethyldiprenorphine ([(18)F]FDPN). Ten athletes were scanned at 2 separate occasions in random order, at rest and after 2 h of endurance running (21.5 +/- 4.7 km). Binding kinetics of [(18)F]FDPN were quantified by basis pursuit denoising (DEPICT software). Statistical parametric mapping (SPM2) was used for voxelwise analyses to determine relative changes in ligand binding after running and correlations of opioid binding with euphoria ratings. Reductions in opioid receptor availability were identified preferentially in prefrontal and limbic/paralimbic brain structures. The level of euphoria was significantly increased after running and was inversely correlated with opioid binding in prefrontal/orbitofrontal cortices, the anterior cingulate cortex, bilateral insula, parainsular cortex, and temporoparietal regions. These findings support the "opioid theory" of the runner's high and suggest region-specific effects in frontolimbic brain areas that are involved in the processing of affective states and mood.
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Affiliation(s)
- Henning Boecker
- Nuklearmedizinische Klinik, Klinikum rechts der Isar, Technische Universität München, 81675 München, Germany.
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Abstract
In vivo functional imaging by means of positron emission tomography (PET) is the sole method for providing a quantitative measurement of mu-, kappa and delta-opioid receptor-mediated signalling in the central nervous system. During the last two decades, measurements of changes to the regional brain opioidergic neuronal activation--mediated by endogenously produced opioid peptides, or exogenously administered opioid drugs--have been conducted in numerous chronic pain conditions, in epilepsy, as well as by stimulant- and opioidergic drugs. Although several PET-tracers have been used clinically for depiction and quantification of the opioid receptors changes, the underlying mechanisms for regulation of changes to the availability of opioid receptors are still unclear. After a presentation of the general signalling mechanisms of the opioid receptor system relevant for PET, a critical survey of the pharmacological properties of some currently available PET-tracers is presented. Clinical studies performed with different PET ligands are also reviewed and the compound-dependent findings are summarized. An outlook is given concluding with the tailoring of tracer properties, in order to facilitate for a selective addressment of dynamic changes to the availability of a single subclass, in combination with an optimization of the quantification framework are essentials for further progress in the field of in vivo opioid receptor imaging.
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Affiliation(s)
- Gjermund Henriksen
- Nuklearmedizinische Klinik und Poliklinik, Klinikum rechts der Isar, Technische Universität München, Ismaningerstrasse 22, D-81675 München, Germany
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