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Németh E, Gyuricza B, Forgács V, Cumming P, Henriksen G, Marton J, Bauer B, Mikecz P, Fekete A. Optimization of a Nucleophilic Two-Step Radiosynthesis of 6- O-(2-[ 18F]fluoroethyl)-6- O-desmethyl-diprenorphine ([ 18F]FE-DPN) for PET Imaging of Brain Opioid Receptors. Int J Mol Sci 2023; 24:13152. [PMID: 37685958 PMCID: PMC10487412 DOI: 10.3390/ijms241713152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 08/15/2023] [Accepted: 08/17/2023] [Indexed: 09/10/2023] Open
Abstract
We have established a method for nucleophilic one-pot, two-step radiosynthesis of the popular opioid receptor radioligand 6-O-(2-[18F]fluoroethyl)-6-O-desmethyl-diprenorphine ([18F]FE-DPN) from the novel precursor 6-O-(2-tosyloxyethyl)-6-O-desmethyl- 3-O-trityl-diprenorphine (TE-TDDPN), which we designate as the Henriksen precursor. We undertook an optimization of the synthesis conditions, aiming to enhance the accessibility of [18F]FE-DPN for positron emission tomography (PET) studies of μ-opioid receptors. Herein, we report an optimized direct nucleophilic 18F-fluorination and the deprotection conditions for a fully automated radiosynthesis of [18F]FE-DPN on a modified GE Tracerlab FX FE synthesis panel. Starting from 1-1.5 GBq of [18F]fluoride and applying an Oasis Max 1cc cartridge for fluorine-18 trapping with a reduced amount of K2CO3 (5.06 μmol K+ ion), [18F]FE-DPN ([18F]11) was produced with 44.5 ± 10.6 RCY (decay-corrected), high radiochemical purity (>99%), and a molar activity of 32.2 ± 11.8 GBq/μmol in 60-65 min.
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Affiliation(s)
- Enikő Németh
- Division of Nuclear Medicine and Translational Imaging, Department of Medical Imaging, Faculty of Medicine, University of Debrecen, Nagyerdei Krt. 98, H-4032 Debrecen, Hungary; (E.N.); (B.G.); (V.F.)
| | - Barbara Gyuricza
- Division of Nuclear Medicine and Translational Imaging, Department of Medical Imaging, Faculty of Medicine, University of Debrecen, Nagyerdei Krt. 98, H-4032 Debrecen, Hungary; (E.N.); (B.G.); (V.F.)
| | - Viktória Forgács
- Division of Nuclear Medicine and Translational Imaging, Department of Medical Imaging, Faculty of Medicine, University of Debrecen, Nagyerdei Krt. 98, H-4032 Debrecen, Hungary; (E.N.); (B.G.); (V.F.)
| | - Paul Cumming
- Department of Nuclear Medicine, Bern University Hospital, Freiburgstraße 18, CH-3010 Bern, Switzerland;
- School of Psychology and Counselling, Queensland University of Technology, Brisbane QLD-4059, Australia
| | - Gjermund Henriksen
- Norwegian Medical Cyclotron Centre Ltd., Sognsvannsveien 20, N-0372 Oslo, Norway;
- Institute of Basic Medical Sciences, University of Oslo, N-0317 Oslo, Norway
- Institute of Physics, University of Oslo, Sem Sælands Vei 24, N-0371 Oslo, Norway
| | - János Marton
- ABX Advanced Biochemical Compounds Biomedizinische Forschungsreagenzien GmbH, Heinrich-Glaeser-Strasse 10-14, D-01454 Radeberg, Germany; (J.M.); (B.B.)
| | - Beate Bauer
- ABX Advanced Biochemical Compounds Biomedizinische Forschungsreagenzien GmbH, Heinrich-Glaeser-Strasse 10-14, D-01454 Radeberg, Germany; (J.M.); (B.B.)
| | - Pál Mikecz
- Division of Nuclear Medicine and Translational Imaging, Department of Medical Imaging, Faculty of Medicine, University of Debrecen, Nagyerdei Krt. 98, H-4032 Debrecen, Hungary; (E.N.); (B.G.); (V.F.)
| | - Anikó Fekete
- Division of Nuclear Medicine and Translational Imaging, Department of Medical Imaging, Faculty of Medicine, University of Debrecen, Nagyerdei Krt. 98, H-4032 Debrecen, Hungary; (E.N.); (B.G.); (V.F.)
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Wang X, Wang T, Fan X, Zhang Z, Wang Y, Li Z. A Molecular Toolbox of Positron Emission Tomography Tracers for General Anesthesia Mechanism Research. J Med Chem 2023; 66:6463-6497. [PMID: 37145921 DOI: 10.1021/acs.jmedchem.2c01965] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
With appropriate radiotracers, positron emission tomography (PET) allows direct or indirect monitoring of the spatial and temporal distribution of anesthetics, neurotransmitters, and biomarkers, making it an indispensable tool for studying the general anesthesia mechanism. In this Perspective, PET tracers that have been recruited in general anesthesia research are introduced in the following order: 1) 11C/18F-labeled anesthetics, i.e., PET tracers made from inhaled and intravenous anesthetics; 2) PET tracers targeting anesthesia-related receptors, e.g., neurotransmitters and voltage-gated ion channels; and 3) PET tracers for studying anesthesia-related neurophysiological effects and neurotoxicity. The radiosynthesis, pharmacodynamics, and pharmacokinetics of the above PET tracers are mainly discussed to provide a practical molecular toolbox for radiochemists, anesthesiologists, and those who are interested in general anesthesia.
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Affiliation(s)
- Xiaoxiao Wang
- Center for Molecular Imaging and Translational Medicine, State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, Department of Laboratory Medicine, School of Public Health, Xiamen University, Xiamen, Fujian 361102, China
| | - Tao Wang
- Center for Molecular Imaging and Translational Medicine, State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, Department of Laboratory Medicine, School of Public Health, Xiamen University, Xiamen, Fujian 361102, China
| | - Xiaowei Fan
- Center for Molecular Imaging and Translational Medicine, State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, Department of Laboratory Medicine, School of Public Health, Xiamen University, Xiamen, Fujian 361102, China
| | - Zhao Zhang
- Department of Anesthesiology, Huashan Hospital, Fudan University, Shanghai 200040, China
| | - Yingwei Wang
- Department of Anesthesiology, Huashan Hospital, Fudan University, Shanghai 200040, China
| | - Zijing Li
- Center for Molecular Imaging and Translational Medicine, State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, Department of Laboratory Medicine, School of Public Health, Xiamen University, Xiamen, Fujian 361102, China
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Afridi HH, Shoaib M, Al-Joufi FA, Shah SWA, Hussain H, Ullah A, Zahoor M, Mughal EU. Synthesis and Investigation of the Analgesic Potential of Enantiomerically Pure Schiff Bases: A Mechanistic Approach. Molecules 2022; 27:molecules27165206. [PMID: 36014445 PMCID: PMC9416351 DOI: 10.3390/molecules27165206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2022] [Revised: 08/05/2022] [Accepted: 08/12/2022] [Indexed: 11/16/2022] Open
Abstract
Schiff bases are a class of organic compounds with azomethine moiety, exhibiting a wide range of biological potentials. In this research, six chiral Schiff bases, three ‘S’ series (H1−H3) and three ‘R’ series (H4−H6), were synthesized. The reaction was neat, which means without a solvent, and occurred at room temperature with a high product yield. The synthesized compounds were evaluated for analgesic potential in vivo at doses of 12.5 and 25 mg/kg using acetic-acid-induced writhing assay, formalin test, tail immersion and hot plate models, followed by investigating the possible involvement of opioid receptors. The compounds H2 and H3 significantly (*** p < 0.001) reduced the writhing frequency, and H3 and H5 significantly (*** p < 0.001) reduced pain in both phases of the formalin test. The compounds H2 and H5 significantly (*** p < 0.001) increased latency at 90 min in tail immersion, while H2 significantly (*** p < 0.001) increased latency at 90 min in the hot plate test. The ‘S’ series Schiff bases, H1−H3, were found more potent than the ‘R’ series compounds, H4−H6. The possible involvement of opioid receptors was also surveyed utilizing naloxone in tail immersion and hot plate models, investigating the involvement of opioid receptors. The synthesized compounds could be used as alternative analgesic agents subjected to further evaluation in other animal models to confirm the observed biological potential.
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Affiliation(s)
- Hamid Hussain Afridi
- Department of Pharmacy, University of Malakand Dir (Lower) at Chakdara, Chakdara 18800, KPK, Pakistan
- Department of Pharmacy, Shaheed Benazir Bhutto University Sheringal Dir (Upper), Dir 18000, KPK, Pakistan
| | - Muhammad Shoaib
- Department of Pharmacy, University of Malakand Dir (Lower) at Chakdara, Chakdara 18800, KPK, Pakistan
| | - Fakhria A. Al-Joufi
- Department of Pharmacology, College of Pharmacy, Jouf University, Aljouf 72341, Saudi Arabia
| | - Syed Wadood Ali Shah
- Department of Pharmacy, University of Malakand Dir (Lower) at Chakdara, Chakdara 18800, KPK, Pakistan
| | - Haya Hussain
- Department of Pharmacy, Shaheed Benazir Bhutto University Sheringal Dir (Upper), Dir 18000, KPK, Pakistan
| | - Abid Ullah
- Department of Pharmacy, Shaheed Benazir Bhutto University Sheringal Dir (Upper), Dir 18000, KPK, Pakistan
| | - Mohammad Zahoor
- Department of Chemistry, University of Malakand Dir (Lower) at Chakdara, Chakdara 18800, KPK, Pakistan
- Correspondence:
| | - Ehsan Ullah Mughal
- Department of Chemistry, University of Gujrat, Gujrat 50700, PB, Pakistan
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Evaluation of analgesic, antiamnesic and antidiarrheal potentials of Medicago denticulata extract using animal model. Saudi J Biol Sci 2021; 28:6352-6358. [PMID: 34759754 PMCID: PMC8568719 DOI: 10.1016/j.sjbs.2021.06.095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 05/27/2021] [Accepted: 06/29/2021] [Indexed: 11/21/2022] Open
Abstract
The analgesic, antidiarrheal, and neuro-pharmacological potentials of Medicago denticulata leaves extract were screened in animal models. Potential analgesic response was noted (*P < 0.05, **P < 0.01, ***P < 0.001) in formalin, acetic acid and heat-induced pain models in a dose-dependent manner. Maximum activity by means of writhing inhibition was documented for Medicago denticulata at 300 mg/kg that was found to be 71.79% (17.43 ± 1.31). In first phase, the Medicago denticulata at a dose of 150 and 300 mg/kg showed analgesic activity and reduced the pain by 54.18% (18.39 ± 1.67) and 62.90% (14.89 ± 1.56), respectively. In second phase, the Medicago denticulata at a dose of 150 and 300 mg/kg showed analgesic activity and reduced the pain by 69.48% (19.78 ± 1.44) and 70.89% (18.86 ± 1.58), respectively. In hot plate method, the Medicago denticulata at a dose of 150 and 300 mg/kg showed the maximum response of 61.16% (8.47 ± 1.23) and 67.39% (10.09 ± 1.04), respectively at 60 min. Scopolamine significantly reduces spontaneous alteration in Y-maze model for antiamnesic activity. Medicago denticulata significantly increased the discrimination index in a dose-dependent manner using novel object recognition test (NORT) model. Exploration time in sec for the novel object was increased significantly (P < 0.001) by donepezil decreased for familiar one with a discrimination index (DI) of 62.18%. Medicago denticulata significantly increased the discrimination index by 60.86% and 57.24% at 300 and 150 mg/kg b.w, respectively. The lowest DI of 53.80% at 75 mg/kg was observed in comparison to the amnesic group. The Medicago denticulata significant decreased the elevated levels of acetylcholinesterase (AChE) and malondialdehyde (MDA and enhancing level of acetylcholine (ACh), superoxide dismutase (SOD) and catalase (CAT) acting as an antioxidant agent. Medicago denticulata reduced the total number of diarrheal feces to lesser extent at dose-dependent manner. From the study results, it is suggested that the Medicago denticulata extract possess good analgesic and antiamnesic activity however the antidiarrheal effects of plant were negligible. In the current study, the traditional use of the plant as a source of medicine has been validated.
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Placzek MS. Imaging Kappa Opioid Receptors in the Living Brain with Positron Emission Tomography. Handb Exp Pharmacol 2021; 271:547-577. [PMID: 34363128 DOI: 10.1007/164_2021_498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Kappa opioid receptor (KOR) neuroimaging using positron emission tomography (PET) has been immensely successful in all phases of discovery and validation in relation to radiotracer development from preclinical imaging to human imaging. There are now several KOR-specific PET radiotracers that can be utilized for neuroimaging, including agonist and antagonist ligands, as well as C-11 and F-18 variants. These technologies will increase KOR PET utilization by imaging centers around the world and have provided a foundation for future studies. In this chapter, I review the advances in KOR radiotracer discovery, focusing on ligands that have been translated into human imaging, and highlight key attributes unique to each KOR PET radiotracer. The utilization of these radiotracers in KOR PET neuroimaging can be subdivided into three major investigational classes: the first, measurement of KOR density; the second, measurement of KOR drug occupancy; the third, detecting changes in endogenous dynorphin following activation or deactivation. Given the involvement of the KOR/dynorphin system in a number of brain disorders including, but not limited to, pain, itch, mood disorders and addiction, measuring KOR density in the living brain will offer insight into the chronic effects of these disorders on KOR tone in humans. Notably, KOR PET has been successful at measuring drug occupancy in the human brain to guide dose selection for maximal therapeutic efficacy while avoiding harmful side effects. Lastly, we discuss the potential of KOR PET to detect changes in endogenous dynorphin in the human brain, to elucidate neural mechanisms and offer critical insight into disease-modifying therapeutics. We conclude with comments on other translational neuroimaging modalities such as MRI that could be used to study KOR-dynorphin tone in the living human brain.
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Affiliation(s)
- Michael S Placzek
- Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA. .,Department of Radiology, Harvard Medical School, Boston, MA, USA.
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Nosova O, Bazov I, Karpyak V, Hallberg M, Bakalkin G. Epigenetic and Transcriptional Control of the Opioid Prodynorphine Gene: In-Depth Analysis in the Human Brain. Molecules 2021; 26:molecules26113458. [PMID: 34200173 PMCID: PMC8201134 DOI: 10.3390/molecules26113458] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 05/26/2021] [Accepted: 06/01/2021] [Indexed: 12/19/2022] Open
Abstract
Neuropeptides serve as neurohormones and local paracrine regulators that control neural networks regulating behavior, endocrine system and sensorimotor functions. Their expression is characterized by exceptionally restricted profiles. Circuit-specific and adaptive expression of neuropeptide genes may be defined by transcriptional and epigenetic mechanisms controlled by cell type and subtype sequence-specific transcription factors, insulators and silencers. The opioid peptide dynorphins play a critical role in neurological and psychiatric disorders, pain processing and stress, while their mutations cause profound neurodegeneration in the human brain. In this review, we focus on the prodynorphin gene as a model for the in-depth epigenetic and transcriptional analysis of expression of the neuropeptide genes. Prodynorphin studies may provide a framework for analysis of mechanisms relevant for regulation of neuropeptide genes in normal and pathological human brain.
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Affiliation(s)
- Olga Nosova
- Department of Pharmaceutical Biosciences, Uppsala University, 75124 Uppsala, Sweden; (I.B.); (M.H.)
- Correspondence: (O.N.); (G.B.)
| | - Igor Bazov
- Department of Pharmaceutical Biosciences, Uppsala University, 75124 Uppsala, Sweden; (I.B.); (M.H.)
| | | | - Mathias Hallberg
- Department of Pharmaceutical Biosciences, Uppsala University, 75124 Uppsala, Sweden; (I.B.); (M.H.)
| | - Georgy Bakalkin
- Department of Pharmaceutical Biosciences, Uppsala University, 75124 Uppsala, Sweden; (I.B.); (M.H.)
- Correspondence: (O.N.); (G.B.)
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Naganawa M, Li S, Nabulsi N, Lin SF, Labaree D, Ropchan J, Gao H, Mei M, Henry S, Matuskey D, Carson RE, Huang Y. Kinetic Modeling and Test-Retest Reproducibility of 11C-EKAP and 11C-FEKAP, Novel Agonist Radiotracers for PET Imaging of the κ-Opioid Receptor in Humans. J Nucl Med 2020; 61:1636-1642. [PMID: 32169917 DOI: 10.2967/jnumed.119.227694] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 03/09/2020] [Indexed: 12/13/2022] Open
Abstract
The κ-opioid receptor (KOR) is implicated in various neuropsychiatric disorders. We previously evaluated an agonist tracer, 11C-GR103545, for PET imaging of KOR in humans. Although 11C-GR103545 showed high brain uptake, good binding specificity, and selectivity for KOR, it displayed slow kinetics and relatively large test-retest variability of total distribution volume (V T) estimates (15%). Therefore, we set out to develop 2 novel KOR agonist radiotracers, 11C-EKAP and 11C-FEKAP. In nonhuman primates, both tracers exhibited faster kinetics than 11C-GR103545 and comparable binding parameters to 11C-GR103545. The aim of this study was to assess their kinetic and binding properties in humans. Methods: Six healthy subjects underwent 120-min test-retest PET scans with both 11C-EKAP and 11C-FEKAP. Metabolite-corrected arterial input functions were measured. Regional time-activity curves were generated for 14 regions of interest. One-tissue-compartment and 2-tissue-compartment (2TC) models and the multilinear analysis-1 (MA1) method were applied to the regional time-activity curves to calculate V T The time stability of V T and test-retest reproducibility were evaluated. Levels of specific binding, as measured by the nondisplaceable binding potential (BP ND) for the 3 tracers (11C-EKAP, 11C-FEKAP, and 11C-GR103545), were compared using a graphical method. Results: For both tracers, regional time-activity curves were fitted well with the 2TC model and MA1 method (t* = 20 min) but not with the 1-tissue-compartment model. Given the unreliably estimated parameters in several fits with the 2TC model and a good V T match between MA1 and 2TC, MA1 was chosen as the appropriate model for both tracers. Mean MA1 V T was highest for 11C-GR103545, followed by 11C-EKAP and then 11C-FEKAP. The minimum scan time for stable V T measurement was 90 and 110 min for 11C-EKAP and 11C-FEKAP, respectively, compared with 140 min for 11C-GR103545. The mean absolute test-retest variability in MA1 V T estimates was 7% and 18% for 11C-EKAP and 11C-FEKAP, respectively. BP ND levels were similar for 11C-FEKAP and 11C-GR103545 but were about 25% lower for 11C-EKAP. Conclusion: The 2 novel KOR agonist tracers showed faster tissue kinetics than 11C-GR103545. Even with a slightly lower BP ND, 11C-EKAP is judged to be a better tracer for imaging and quantification of KOR in humans, on the basis of the shorter minimum scan time and the excellent test-retest reproducibility of regional V T.
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Affiliation(s)
- Mika Naganawa
- Yale PET Center, Yale University, New Haven, Connecticut
| | - Songye Li
- Yale PET Center, Yale University, New Haven, Connecticut
| | - Nabeel Nabulsi
- Yale PET Center, Yale University, New Haven, Connecticut
| | - Shu-Fei Lin
- Yale PET Center, Yale University, New Haven, Connecticut
| | - David Labaree
- Yale PET Center, Yale University, New Haven, Connecticut
| | - Jim Ropchan
- Yale PET Center, Yale University, New Haven, Connecticut
| | - Hong Gao
- Yale PET Center, Yale University, New Haven, Connecticut
| | - Michael Mei
- Yale PET Center, Yale University, New Haven, Connecticut
| | - Shannan Henry
- Yale PET Center, Yale University, New Haven, Connecticut
| | - David Matuskey
- Yale PET Center, Yale University, New Haven, Connecticut
| | | | - Yiyun Huang
- Yale PET Center, Yale University, New Haven, Connecticut
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A Survey of Molecular Imaging of Opioid Receptors. Molecules 2019; 24:molecules24224190. [PMID: 31752279 PMCID: PMC6891617 DOI: 10.3390/molecules24224190] [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: 10/21/2019] [Revised: 11/11/2019] [Accepted: 11/13/2019] [Indexed: 01/09/2023] Open
Abstract
The discovery of endogenous peptide ligands for morphine binding sites occurred in parallel with the identification of three subclasses of opioid receptor (OR), traditionally designated as μ, δ, and κ, along with the more recently defined opioid-receptor-like (ORL1) receptor. Early efforts in opioid receptor radiochemistry focused on the structure of the prototype agonist ligand, morphine, although N-[methyl-11C]morphine, -codeine and -heroin did not show significant binding in vivo. [11C]Diprenorphine ([11C]DPN), an orvinol type, non-selective OR antagonist ligand, was among the first successful PET tracers for molecular brain imaging, but has been largely supplanted in research studies by the μ-preferring agonist [11C]carfentanil ([11C]Caf). These two tracers have the property of being displaceable by endogenous opioid peptides in living brain, thus potentially serving in a competition-binding model. Indeed, many clinical PET studies with [11C]DPN or [11C]Caf affirm the release of endogenous opioids in response to painful stimuli. Numerous other PET studies implicate μ-OR signaling in aspects of human personality and vulnerability to drug dependence, but there have been very few clinical PET studies of μORs in neurological disorders. Tracers based on naltrindole, a non-peptide antagonist of the δ-preferring endogenous opioid enkephalin, have been used in PET studies of δORs, and [11C]GR103545 is validated for studies of κORs. Structures such as [11C]NOP-1A show selective binding at ORL-1 receptors in living brain. However, there is scant documentation of δ-, κ-, or ORL1 receptors in healthy human brain or in neurological and psychiatric disorders; here, clinical PET research must catch up with recent progress in radiopharmaceutical chemistry.
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