1
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Brailoiu E, Barr JL, Wittorf HN, Inan S, Unterwald EM, Brailoiu GC. Modulation of the Blood-Brain Barrier by Sigma-1R Activation. Int J Mol Sci 2024; 25:5147. [PMID: 38791182 PMCID: PMC11121402 DOI: 10.3390/ijms25105147] [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: 03/11/2024] [Revised: 05/05/2024] [Accepted: 05/07/2024] [Indexed: 05/26/2024] Open
Abstract
Sigma non-opioid intracellular receptor 1 (Sigma-1R) is an intracellular chaperone protein residing on the endoplasmic reticulum at the mitochondrial-associated membrane (MAM) region. Sigma-1R is abundant in the brain and is involved in several physiological processes as well as in various disease states. The role of Sigma-1R at the blood-brain barrier (BBB) is incompletely characterized. In this study, the effect of Sigma-1R activation was investigated in vitro on rat brain microvascular endothelial cells (RBMVEC), an important component of the blood-brain barrier (BBB), and in vivo on BBB permeability in rats. The Sigma-1R agonist PRE-084 produced a dose-dependent increase in mitochondrial calcium, and mitochondrial and cytosolic reactive oxygen species (ROS) in RBMVEC. PRE-084 decreased the electrical resistance of the RBMVEC monolayer, measured with the electric cell-substrate impedance sensing (ECIS) method, indicating barrier disruption. These effects were reduced by pretreatment with Sigma-1R antagonists, BD 1047 and NE 100. In vivo assessment of BBB permeability in rats indicates that PRE-084 produced a dose-dependent increase in brain extravasation of Evans Blue and sodium fluorescein brain; the effect was reduced by the Sigma-1R antagonists. Immunocytochemistry studies indicate that PRE-084 produced a disruption of tight and adherens junctions and actin cytoskeleton. The brain microcirculation was directly visualized in vivo in the prefrontal cortex of awake rats with a miniature integrated fluorescence microscope (aka, miniscope; Doric Lenses Inc.). Miniscope studies indicate that PRE-084 increased sodium fluorescein extravasation in vivo. Taken together, these results indicate that Sigma-1R activation promoted oxidative stress and increased BBB permeability.
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Affiliation(s)
- Eugen Brailoiu
- Center for Substance Abuse Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA; (E.B.); (J.L.B.); (S.I.)
- Department of Neural Sciences, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
| | - Jeffrey L. Barr
- Center for Substance Abuse Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA; (E.B.); (J.L.B.); (S.I.)
| | - Hailey N. Wittorf
- Department of Pharmaceutical Sciences, Jefferson College of Pharmacy, Thomas Jefferson University, Philadelphia, PA 19107, USA;
| | - Saadet Inan
- Center for Substance Abuse Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA; (E.B.); (J.L.B.); (S.I.)
| | - Ellen M. Unterwald
- Center for Substance Abuse Research, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA; (E.B.); (J.L.B.); (S.I.)
- Department of Neural Sciences, Lewis Katz School of Medicine at Temple University, Philadelphia, PA 19140, USA
| | - Gabriela Cristina Brailoiu
- Department of Pharmaceutical Sciences, Jefferson College of Pharmacy, Thomas Jefferson University, Philadelphia, PA 19107, USA;
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2
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Wang T, Jia H. The Sigma Receptors in Alzheimer's Disease: New Potential Targets for Diagnosis and Therapy. Int J Mol Sci 2023; 24:12025. [PMID: 37569401 PMCID: PMC10418732 DOI: 10.3390/ijms241512025] [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: 06/16/2023] [Revised: 07/14/2023] [Accepted: 07/16/2023] [Indexed: 08/13/2023] Open
Abstract
Sigma (σ) receptors are a class of unique proteins with two subtypes: the sigma-1 (σ1) receptor which is situated at the mitochondria-associated endoplasmic reticulum (ER) membrane (MAM), and the sigma-2 (σ2) receptor, located in the ER-resident membrane. Increasing evidence indicates the involvement of both σ1 and σ2 receptors in the pathogenesis of Alzheimer's disease (AD), and thus these receptors represent two potentially effective biomarkers for emerging AD therapies. The availability of optimal radioligands for positron emission tomography (PET) neuroimaging of the σ1 and σ2 receptors in humans will provide tools to monitor AD progression and treatment outcomes. In this review, we first summarize the significance of both receptors in the pathophysiology of AD and highlight AD therapeutic strategies related to the σ1 and σ2 receptors. We then survey the potential PET radioligands, with an emphasis on the requirements of optimal radioligands for imaging the σ1 or σ2 receptors in humans. Finally, we discuss current challenges in the development of PET radioligands for the σ1 or σ2 receptors, and the opportunities for neuroimaging to elucidate the σ1 and σ2 receptors as novel biomarkers for early AD diagnosis, and for monitoring of disease progression and AD drug efficacy.
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Affiliation(s)
- Tao Wang
- Key Laboratory of Radiopharmaceuticals (Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China;
- Department of Nuclear Medicine, Xinqiao Hospital, Army Medical University, Chongqing 400037, China
| | - Hongmei Jia
- Key Laboratory of Radiopharmaceuticals (Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China;
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3
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Blicker L, González-Cano R, Laurini E, Nieto FR, Schmidt J, Schepmann D, Pricl S, Wünsch B. Conformationally Restricted σ 1 Receptor Antagonists from (-)-Isopulegol. J Med Chem 2023; 66:4999-5020. [PMID: 36946301 DOI: 10.1021/acs.jmedchem.2c02081] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2023]
Abstract
Antagonists at σ1 receptors have great potential for the treatment of neuropathic pain. Starting from monoterpene (-)-isopulegol (1), aminodiols 8-11 were obtained and transformed into bicyclic 13-16 and tricyclic ligands 19-22. Aminodiols 8-11 showed higher σ1 affinity than the corresponding bicyclic 13-16 and tricyclic derivatives 19-22. (R)-configuration in the side chain of aminodiols (8 and 10) led to higher σ1 affinity than (S)-configuration (9 and 11). 4-Benzylpiperidines (b-series) revealed higher σ1 affinity than 4-phenylbutylamines (a-series). Aminodiol 8b showed very high σ1 affinity (Ki = 1.2 nM), excellent selectivity over σ2 receptors, and promising logD7.4 (3.05) and lipophilic ligand efficiency (5.87) values. Molecular dynamics simulations were conducted to analyze the σ1 affinity and selectivity on an atomistic level. In the capsaicin assay, 8b exhibited similar antiallodynic activity to the prototypical σ1 antagonist S1RA. The antiallodynic activity of 8b was removed by co-application of the σ1 agonist PRE-084, proving σ1 antagonism being involved in the antiallodynic effect.
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Affiliation(s)
- Luca Blicker
- Institut für Pharmazeutische und Medizinische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 48, D-48149 Münster, Germany
| | - Rafael González-Cano
- Department of Pharmacology, Faculty of Medicine and Biomedical Research Center (Neurosciences Institute), Biosanitary Research Institute ibs. GRANADA, University of Granada, Avenida de la Investigación 11, Granada 18016, Spain
| | - Erik Laurini
- Molecular Biology and Nanotechnology Laboratory (MolBNL@UniTS), DEA, University of Trieste, 34127 Trieste, Italy
| | - Francisco R Nieto
- Department of Pharmacology, Faculty of Medicine and Biomedical Research Center (Neurosciences Institute), Biosanitary Research Institute ibs. GRANADA, University of Granada, Avenida de la Investigación 11, Granada 18016, Spain
| | - Judith Schmidt
- Institut für Pharmazeutische und Medizinische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 48, D-48149 Münster, Germany
| | - Dirk Schepmann
- Institut für Pharmazeutische und Medizinische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 48, D-48149 Münster, Germany
| | - Sabrina Pricl
- Molecular Biology and Nanotechnology Laboratory (MolBNL@UniTS), DEA, University of Trieste, 34127 Trieste, Italy
- Department of General Biophysics, Faculty of Biology and Environmental Protection, University of Lodz, 90-136 Lodz, Poland
| | - Bernhard Wünsch
- Institut für Pharmazeutische und Medizinische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 48, D-48149 Münster, Germany
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4
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Venkataraman AV, Mansur A, Rizzo G, Bishop C, Lewis Y, Kocagoncu E, Lingford-Hughes A, Huiban M, Passchier J, Rowe JB, Tsukada H, Brooks DJ, Martarello L, Comley RA, Chen L, Schwarz AJ, Hargreaves R, Gunn RN, Rabiner EA, Matthews PM. Widespread cell stress and mitochondrial dysfunction occur in patients with early Alzheimer's disease. Sci Transl Med 2022; 14:eabk1051. [PMID: 35976998 DOI: 10.1126/scitranslmed.abk1051] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Cell stress and impaired oxidative phosphorylation are central to mechanisms of synaptic loss and neurodegeneration in the cellular pathology of Alzheimer's disease (AD). In this study, we quantified the in vivo expression of the endoplasmic reticulum stress marker, sigma 1 receptor (S1R), using [11C]SA4503 positron emission tomography (PET), the mitochondrial complex I (MC1) with [18F]BCPP-EF, and the presynaptic vesicular protein SV2A with [11C]UCB-J in 12 patients with early AD and in 16 cognitively normal controls. We integrated these molecular measures with assessments of regional brain volumes and cerebral blood flow (CBF) measured with magnetic resonance imaging arterial spin labeling. Eight patients with AD were followed longitudinally to estimate the rate of change of the physiological and structural pathology markers with disease progression. The patients showed widespread increases in S1R (≤ 27%) and regional reduction in MC1 (≥ -28%) and SV2A (≥ -25%) radioligand binding, brain volume (≥ -23%), and CBF (≥ -26%). [18F]BCPP-EF PET MC1 binding (≥ -12%) and brain volumes (≥ -5%) showed progressive reductions over 12 to 18 months, suggesting that they both could be used as pharmacodynamic indicators in early-stage therapeutics trials. Associations of reduced MC1 and SV2A and increased S1R radioligand binding with reduced cognitive performance in AD, although exploratory, suggested a loss of metabolic functional reserve with disease. Our study thus provides in vivo evidence for widespread, clinically relevant cellular stress and bioenergetic abnormalities in early AD.
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Affiliation(s)
- Ashwin V Venkataraman
- Department of Brain Sciences, Imperial College London, London W12 0NN, UK.,UK Dementia Research Institute at Imperial College London, London W12 0NN, UK
| | | | - Gaia Rizzo
- Department of Brain Sciences, Imperial College London, London W12 0NN, UK.,Invicro LLC, London W12 0NN, UK
| | | | | | | | | | | | | | | | - Hideo Tsukada
- Hamamatsu Photonics, Hamakita, Hamamatsu, Shizuoka 4348601, Japan
| | - David J Brooks
- University of Newcastle upon Tyne, Newcastle NE2 4HH, UK.,Department of Clinical Medicine, Aarhus University, Aarhus 8200, Denmark
| | | | | | | | | | | | - Roger N Gunn
- Department of Brain Sciences, Imperial College London, London W12 0NN, UK.,Invicro LLC, London W12 0NN, UK
| | - Eugenii A Rabiner
- Invicro LLC, London W12 0NN, UK.,King's College London, London SE5 8AF, UK
| | - Paul M Matthews
- Department of Brain Sciences, Imperial College London, London W12 0NN, UK.,UK Dementia Research Institute at Imperial College London, London W12 0NN, UK
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5
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Rabiner EA, Smith K, Bennett C, Rizzo G, Lewis Y, Mundin G, Dooner H, Oksche A. Pharmacokinetics and brain σ1 receptor occupancy of MR309, a selective σ1 receptor antagonist. Br J Clin Pharmacol 2022; 88:1644-1654. [PMID: 34156715 DOI: 10.1111/bcp.14952] [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: 02/16/2021] [Revised: 06/02/2021] [Accepted: 06/09/2021] [Indexed: 11/30/2022] Open
Abstract
AIMS Preclinical studies of MR309, a selective sigma-1 receptor (σ1R) antagonist, support a potential role in treating neuropathic pain. We report 2 studies that provide insight into the pharmacokinetics (PK) and brain σ1R binding of MR309. METHODS Steady-state PK of MR309 (400 mg once daily and 200 mg twice-daily [BID] for 10 days; EudraCT 2015-001818-99 [PK study]) and the relationship between MR309 plasma exposure and brain σ1R occupancy (EudraCT 2017-000670-11 [positron emission tomography study]) were investigated in healthy volunteers. Positron emission tomography using the σ1R ligand [11 C]SA4503 was conducted at baseline, and 2 and 8 hours after a single dose of MR309 (200-800 mg). The relationship between brain σ1R occupancy and MR309 exposure was explored using data-driven model fitting. RESULTS MR309 was well tolerated, brain σ1R occupancy ranged between 30.5 and 74.9% following single-dose MR309 (n = 7). MR309 BID provided a plasma PK profile with less fluctuation than once daily dosing (n = 16). MR309 200 mg BID yielded average steady state plasma concentrations between 2000 and 4000 ng/mL in the PK study, which corresponded to an estimated brain σ1R occupancy of 59-74%. CONCLUSION MR309 200 mg BID dose was below the 75% σ1R occupancy threshold expected to elicit maximal antinociceptive effect as observed in neuropathic pain models. Further investigations of MR309 for neuropathic pain will require higher brain σ1R occupancy, and establish the optimal dose by elucidating the clinical impact of a broad range of brain σ1R occupancy across different neuropathic pain indications.
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Affiliation(s)
- Eugenii A Rabiner
- Invicro(former Imanova Ltd), A Konica Minolta Company, London, UK
- Centre for Neuroimaging Sciences, Institute of Psychiatry, Psychology and Neuroscience, King's College, London, UK
| | | | | | - Gaia Rizzo
- Invicro(former Imanova Ltd), A Konica Minolta Company, London, UK
- Division of Brain Sciences, Department of Medicine, Imperial College, London, UK
| | - Yvonne Lewis
- Invicro(former Imanova Ltd), A Konica Minolta Company, London, UK
| | | | | | - Alexander Oksche
- Mundipharma Research Limited, Cambridge, UK
- Institut für medizinische und pharmazeutische Prüfungsfragen, Mainz, Germany
- Rudolf-Buchheim Institute of Pharmacology, Giessen, Germany
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6
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Agha H, McCurdy CR. In vitro and in vivo sigma 1 receptor imaging studies in different disease states. RSC Med Chem 2021; 12:154-177. [PMID: 34046607 PMCID: PMC8127618 DOI: 10.1039/d0md00186d] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 09/02/2020] [Indexed: 12/11/2022] Open
Abstract
The sigma receptor system has been classified into two distinct subtypes, sigma 1 (σ1R) and sigma 2 (σ2R). Sigma 1 receptors (σ1Rs) are involved in many neurodegenerative diseases and different central nervous system disorders such as Alzheimer's disease, Parkinson's disease, schizophrenia, and drug addiction, and pain. This makes them attractive targets for developing radioligands as tools to gain a better understanding of disease pathophysiology and clinical diagnosis. Over the years, several σ1R radioligands have been developed to image the changes in σ1R distribution and density providing insights into their role in disease development. Moreover, the involvement of both σ1Rs and σ2Rs with cancer make these ligands, especially those that are σ2R selective, great tools for imaging different types of tumors. This review will discuss the principles of molecular imaging using PET and SPECT, known σ1R radioligands and their applications for labelling σ1Rs under different disease conditions. Furthermore, this review will highlight σ1R radioligands that have demonstrated considerable potential as biomarkers, and an opportunity to fulfill the ultimate goal of better healthcare outcomes and improving human health.
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Affiliation(s)
- Hebaalla Agha
- Department of Medicinal Chemistry, College of Pharmacy, University of Florida Gainesville FL 32610 USA +(352) 273 7705 +1 (352) 294 8691
| | - Christopher R McCurdy
- Department of Medicinal Chemistry, College of Pharmacy, University of Florida Gainesville FL 32610 USA +(352) 273 7705 +1 (352) 294 8691
- UF Translational Drug Development Core, University of Florida Gainesville FL 32610 USA
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7
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Tian J, He Y, Deuther-Conrad W, Fu H, Xie F, Zhang Y, Wang T, Zhang X, Zhang J, Brust P, Huang Y, Jia H. Synthesis and evaluation of new 1-oxa-8-azaspiro[4.5]decane derivatives as candidate radioligands for sigma-1 receptors. Bioorg Med Chem 2020; 28:115560. [PMID: 32616183 DOI: 10.1016/j.bmc.2020.115560] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Revised: 05/12/2020] [Accepted: 05/16/2020] [Indexed: 01/01/2023]
Abstract
We report the design, synthesis, and evaluation of a series of 1-oxa-8-azaspiro[4.5]decane and 1,5-dioxa-9-azaspiro[5.5]undecane derivatives as selective σ1 receptor ligands. All seven ligands exhibited nanomolar affinity for σ1 receptors (Ki(σ1) = 0.47 - 12.1 nM) and moderate selectivity over σ2 receptors (Ki(σ2)/ Ki(σ1) = 2 - 44). Compound 8, with the best selectivity among these ligands, was selected for radiolabeling and further evaluation. Radioligand [18F]8 was prepared via nucleophilic 18F-substitution of the corresponding tosylate precursor, with an overall isolated radiochemical yield of 12-35%, a radiochemical purity of greater than 99%, and molar activity of 94 - 121 GBq/μmol. Biodistribution studies of [18F]8 in mice demonstrated high initial brain uptake at 2 min. Pretreatment with SA4503 resulted in significantly reduced brain-to-blood ratio (70% - 75% at 30 min). Ex vivo autoradiography in ICR mice demonstrated high accumulation of the radiotracer in σ1 receptor-rich brain areas. These findings suggest that [18F]8 could be a lead compound for further structural modifications to develop potential brain imaging agents for σ1 receptors.
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Affiliation(s)
- Jiale Tian
- Key Laboratory of Radiopharmaceuticals (Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Yingfang He
- Key Laboratory of Radiopharmaceuticals (Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Winnie Deuther-Conrad
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, 04318 Leipzig, Germany
| | - Hualong Fu
- Key Laboratory of Radiopharmaceuticals (Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Fang Xie
- PET Center, Huashan Hospital, Fudan University, Shanghai 200040, China
| | - Ying Zhang
- Key Laboratory of Radiopharmaceuticals (Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Tao Wang
- Key Laboratory of Radiopharmaceuticals (Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Xiaojun Zhang
- Nuclear Medicine Department, Chinese PLA General Hospital, Beijing 100853, China
| | - Jinming Zhang
- Nuclear Medicine Department, Chinese PLA General Hospital, Beijing 100853, China.
| | - Peter Brust
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, 04318 Leipzig, Germany
| | - Yiyun Huang
- Yale PET Center, Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, CT, USA
| | - Hongmei Jia
- Key Laboratory of Radiopharmaceuticals (Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China.
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8
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Jia H, Cai Z, Holden D, He Y, Lin SF, Li S, Baum E, Shirali A, Kapinos M, Gao H, Ropchan J, Huang Y. Positron Emission Tomography Imaging Evaluation of a Novel 18F-Labeled Sigma-1 Receptor Radioligand in Cynomolgus Monkeys. ACS Chem Neurosci 2020; 11:1673-1681. [PMID: 32356969 DOI: 10.1021/acschemneuro.0c00171] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
We report a convenient radiosynthesis and the first positron emission tomography (PET) imaging evaluation of [18F]FBFP as a potent sigma-1 (σ1) receptor radioligand with advantageous characteristics. [18F]FBFP was synthesized in one step from an iodonium ylide precursor. In cynomolgus monkeys, [18F]FBFP displayed high brain uptake and suitable tissue kinetics for quantitative analysis. It exhibited heterogeneous distribution with higher regional volume of distribution (VT) values in the amygdala, hippocampus, insula, and frontal cortex. Pretreatment with the σ1 receptor agonist SA4503 (0.5 mg/kg) significantly reduced radioligand uptake in the monkey brain (>95%), indicating high binding specificity of [18F]FBFP in vivo. Compared with (S)-[18F]fluspidine, [18F]FBFP possessed higher regional nondisplaceable binding potential (BPND) values across the brain regions. These findings demonstrate that [18F]FBFP is a highly promising PET radioligand for imaging and quantification of σ1 receptors in humans.
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Affiliation(s)
- Hongmei Jia
- Key Laboratory of Radiopharmaceuticals (Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Zhengxin Cai
- Yale PET Center, Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, Connecticut 06520, United States
| | - Daniel Holden
- Yale PET Center, Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, Connecticut 06520, United States
| | - Yingfang He
- Key Laboratory of Radiopharmaceuticals (Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Shu-Fei Lin
- Yale PET Center, Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, Connecticut 06520, United States
| | - Songye Li
- Yale PET Center, Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, Connecticut 06520, United States
| | - Evan Baum
- Yale PET Center, Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, Connecticut 06520, United States
| | - Anupama Shirali
- Yale PET Center, Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, Connecticut 06520, United States
| | - Michael Kapinos
- Yale PET Center, Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, Connecticut 06520, United States
| | - Hong Gao
- Yale PET Center, Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, Connecticut 06520, United States
| | - Jim Ropchan
- Yale PET Center, Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, Connecticut 06520, United States
| | - Yiyun Huang
- Yale PET Center, Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, Connecticut 06520, United States
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9
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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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10
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Mansur A, Rabiner EA, Comley RA, Lewis Y, Middleton LT, Huiban M, Passchier J, Tsukada H, Gunn RN. Characterization of 3 PET Tracers for Quantification of Mitochondrial and Synaptic Function in Healthy Human Brain: 18F-BCPP-EF, 11C-SA-4503, and 11C-UCB-J. J Nucl Med 2019; 61:96-103. [PMID: 31324712 DOI: 10.2967/jnumed.119.228080] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 06/04/2019] [Indexed: 11/16/2022] Open
Abstract
Mitochondrial complex 1 is involved in maintaining brain bioenergetics; σ-1 receptor responds to neuronal stress; and synaptic vesicle protein 2A reflects synaptic integrity. Expression of each of these proteins is altered in neurodegenerative diseases. Here, we characterize the kinetic behavior of 3 PET radioligands-18F-BCPP-EF, 11C-SA-4503, and 11C-UCB-J-for the measurement of mitochondrial complex 1, σ-1 receptor, and synaptic vesicle protein 2A, respectively, and determine appropriate analysis workflows for their application in future studies of the in vivo molecular pathology of these diseases. Methods: Twelve human subjects underwent dynamic PET scans with each radioligand, including associated arterial blood sampling. A range of kinetic models was investigated to identify an optimal kinetic analysis method for each radioligand and a suitable acquisition duration. Results: All 3 radioligands readily entered the brain and yielded heterogeneous uptake consistent with the known distribution of the targets. The optimal models determined for the regional estimates of volume of distribution were multilinear analysis 1 (MA1) and the 2-tissue-compartment model for 18F-BCPP-EF, MA1 for 11C-SA-4503, and both MA1 and the 1-tissue-compartment model for 11C-UCB-J. Acquisition times of 70, 80, and 60 min for 18F-BCPP-EF, 11C-SA-4503, 11C-UCB-J, respectively, provided good estimates of regional volume of distribution values. An effect of age was observed on 18F-BCPP-EF and 11C-UCB-J signal in the caudate. Conclusion: These ligands can be assessed for their potential to stratify patients or monitor the progression of molecular neuropathology in neurodegenerative diseases.
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Affiliation(s)
- Ayla Mansur
- Invicro LLC, London, United Kingdom .,Division of Brain Sciences, Imperial College London, London, United Kingdom
| | - Eugenii A Rabiner
- Invicro LLC, London, United Kingdom.,King's College London, London, United Kingdom
| | | | | | - Lefkos T Middleton
- Neuroepidemiology and Ageing Research Unit, Imperial College London, London, United Kingdom; and
| | | | - Jan Passchier
- Invicro LLC, London, United Kingdom.,Division of Brain Sciences, Imperial College London, London, United Kingdom
| | - Hideo Tsukada
- Hamamatsu Photonics, Hamamatsu City, Shizuoka, Japan
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11
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Ye J, Wang L, Deuther-Conrad W, Chen Y, Zhang X, Zhang J, Huang Y, Brust P, Jia H. 18 F-Labeled benzylpiperazine derivatives as highly selective ligands for imaging σ 1 receptor with positron emission tomography. J Labelled Comp Radiopharm 2019; 62:425-437. [PMID: 30991462 DOI: 10.1002/jlcr.3738] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 04/04/2019] [Accepted: 04/09/2019] [Indexed: 11/07/2022]
Abstract
We report the design, synthesis, and evaluation of a new series of benzylpiperazine derivatives as selective σ1 receptor ligands. All seven ligands possessed low nanomolar affinity for σ1 receptors (Ki (σ1 ) = 0.31-4.19 nM) and high subtype selectivity (Ki (σ2 )/Ki (σ1 ) = 50-2448). The fluoroethoxy analogues also exhibited high selectivity toward the vesicular acetylcholine transporter (Ki (VAChT)/Ki (σ1 ) = 99-18252). The corresponding radiotracers [18 F]13, [18 F]14, and [18 F]16 with high selectivity (Ki (σ2 )/Ki (σ1 ) > 100, Ki (VAChT)/Ki (σ1 ) > 1000) were prepared in 42% to 55% radiochemical yields (corrected for decay), greater than 99% radiochemical purity (RCP), and molar activity of about 120 GBq/μmol at the end of synthesis (EOS). All three radiotracers showed high initial brain uptake in mouse (8.37-11.48% ID/g at 2 min), which was not affected by pretreatment with cyclosporine A, suggesting that they are not substrates for permeability-glycoprotein (P-gp). Pretreatment with SA4503 or haloperidol resulted in significantly reduced brain uptake (35%-62% decrease at 30 min). In particular, [18 F]16 displayed high brain-to-blood ratios and high in vivo metabolic stability. Although it may not be an optimal neuroimaging agent because of its slow kinetics in the mouse brain, [18 F]16 can serve as a lead compound for further structural modifications to explore new potential radiotracers for σ1 receptors.
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Affiliation(s)
- Jiajun Ye
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, China
| | - Liang Wang
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, China
| | - Winnie Deuther-Conrad
- Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Helmholtz-Zentrum Dresden-Rossendorf, Leipzig, Germany
| | - Yuanyuan Chen
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, China
| | - Xiaojun Zhang
- Nuclear Medicine Department, Chinese PLA General Hospital, Beijing, China
| | - Jinming Zhang
- Nuclear Medicine Department, Chinese PLA General Hospital, Beijing, China
| | - Yiyun Huang
- Yale PET Center, Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Peter Brust
- Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Helmholtz-Zentrum Dresden-Rossendorf, Leipzig, Germany
| | - Hongmei Jia
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, China
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Imaging sigma receptors in the brain: New opportunities for diagnosis of Alzheimer's disease and therapeutic development. Neurosci Lett 2018; 691:3-10. [PMID: 30040970 DOI: 10.1016/j.neulet.2018.07.033] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 07/09/2018] [Accepted: 07/20/2018] [Indexed: 10/28/2022]
Abstract
The sigma-1 (σ1) receptor is a chaperone protein located on the mitochondria-associated membrane of the endoplasmic reticulum, while the sigma-2 receptor (σ2) is an endoplasmic reticulum-resident membrane protein. Recent evidence indicates that both of these receptors figure prominently in the pathophysiology of Alzheimer's disease (AD) and thus are targets for the development of novel, disease-modifying therapeutic strategies. Radioligand-based molecular imaging technique such as positron emission tomography (PET) imaging is a powerful tool for the investigation of protein target expression and function in living subjects. In this review, we survey the development of PET radioligands for the σ1 or σ2 receptors and assess their potential for human imaging applications. The availability of PET imaging with σ1 or σ2 receptor-specific radioligands in humans will allow the investigation of these receptors in vivo and lead to further understanding of their respective roles in AD pathogenesis and progression. Moreover, PET imaging can be used in target occupancy studies to assess target engagement and correlate receptor occupancy and therapeutic response of σ1 receptor agonists and σ2 receptor antagonists currently in clinical trials. It is expected that neuroimaging of σ1 and σ2 receptors in the brain will shed new light on AD pathophysiology and may provide us with new biomarkers for diagnosis of AD and efficacy monitoring of emerging AD therapeutic strategies.
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13
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Baum E, Cai Z, Bois F, Holden D, Lin SF, Lara-Jaime T, Kapinos M, Chen Y, Deuther-Conrad W, Fischer S, Dukic-Stefanovic S, Bunse P, Wünsch B, Brust P, Jia H, Huang Y. PET Imaging Evaluation of Four σ 1 Radiotracers in Nonhuman Primates. J Nucl Med 2017; 58:982-988. [PMID: 28232607 DOI: 10.2967/jnumed.116.188052] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Accepted: 02/09/2017] [Indexed: 01/24/2023] Open
Abstract
The σ1 receptors (S1Rs) are implicated in a variety of diseases including Alzheimer disease and cancer. Previous PET S1R radiotracers are characterized by slow kinetics or off-target binding that impedes their use in humans. Here, we report the first PET imaging evaluation in rhesus monkeys of 4 18F-labeled spirocyclic piperidine-based PET radiotracers (18F-1 to 18F-4). Methods: Baseline scans for the 4 radiotracers were obtained on an adult male rhesus monkey. Blocking scans were obtained with the S1R-selective agonist SA4503 to assess binding specificity of 18F-2 and 18F-4 Arterial input functions were measured, and binding parameters were determined with kinetic modeling analysis. Results: In the rhesus brain, all 4 radiotracers showed high and fast uptake. Tissue activity washout was rapid for 18F-2 and 18F-4, and much slower for 18F-1 and 18F-3, in line with their respective in vitro S1R-binding affinities. Both the 1-tissue-compartment and multilinear analysis-1 kinetic models provided good fits of time-activity curves and reliable estimates of distribution volume. Regional distribution volume values were highest in the cingulate cortex and lowest in the thalamus for all radiotracers. 18F-4 showed greater differential uptake across brain regions and 3-fold-higher binding potential than 18F-2 SA4503 at the dose of 0.5 mg/kg blocked approximately 85% (18F-2) and 95% (18F-4) of radiotracer binding. Conclusion: Tracers 18F-2 and 18F-4 displayed high brain uptake and fast tissue kinetics, with 18F-4 having higher specific binding signals than 18F-2 in the same monkey. Taken together, these data indicate that both 18F-2 and 18F-4 possess the requisite kinetic and imaging properties as viable PET tracers for imaging S1R in the human brain.
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Affiliation(s)
- Evan Baum
- PET Center, Department of Radiology and Biomedical Imaging, Yale University, New Haven, Connecticut
| | - Zhengxin Cai
- PET Center, Department of Radiology and Biomedical Imaging, Yale University, New Haven, Connecticut
| | - Frederic Bois
- PET Center, Department of Radiology and Biomedical Imaging, Yale University, New Haven, Connecticut
| | - Daniel Holden
- PET Center, Department of Radiology and Biomedical Imaging, Yale University, New Haven, Connecticut
| | - Shu-Fei Lin
- PET Center, Department of Radiology and Biomedical Imaging, Yale University, New Haven, Connecticut
| | - Teresa Lara-Jaime
- PET Center, Department of Radiology and Biomedical Imaging, Yale University, New Haven, Connecticut
| | - Michael Kapinos
- PET Center, Department of Radiology and Biomedical Imaging, Yale University, New Haven, Connecticut
| | - Yuanyuan Chen
- Ministry of Education Key Laboratory of Radiopharmaceuticals, College of Chemistry, Beijing Normal University, Beijing, China
| | - Winnie Deuther-Conrad
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Leipzig, Germany; and
| | - Steffen Fischer
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Leipzig, Germany; and
| | - Sladjana Dukic-Stefanovic
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Leipzig, Germany; and
| | - Paul Bunse
- Department of Pharmaceutical and Medicinal Chemistry, Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Bernhard Wünsch
- Department of Pharmaceutical and Medicinal Chemistry, Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Peter Brust
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Leipzig, Germany; and
| | - Hongmei Jia
- Ministry of Education Key Laboratory of Radiopharmaceuticals, College of Chemistry, Beijing Normal University, Beijing, China
| | - Yiyun Huang
- PET Center, Department of Radiology and Biomedical Imaging, Yale University, New Haven, Connecticut
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14
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He Y, Xie F, Ye J, Deuther-Conrad W, Cui B, Wang L, Lu J, Steinbach J, Brust P, Huang Y, Lu J, Jia H. 1-(4-[ 18F]Fluorobenzyl)-4-[(tetrahydrofuran-2-yl)methyl]piperazine: A Novel Suitable Radioligand with Low Lipophilicity for Imaging σ 1 Receptors in the Brain. J Med Chem 2017; 60:4161-4172. [PMID: 28409931 DOI: 10.1021/acs.jmedchem.6b01723] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
We have designed and synthesized novel piperazine compounds with low lipophilicity as σ1 receptor ligands. 1-(4-Fluorobenzyl)-4-[(tetrahydrofuran-2-yl)methyl]piperazine (10) possessed a low nanomolar σ1 receptor affinity and a high selectivity toward the vesicular acetylcholine transporter (>2000-fold), σ2 receptors (52-fold), and adenosine A2A, adrenergic α2, cannabinoid CB1, dopamine D1, D2L, γ-aminobutyric acid A (GABAA), NMDA, melatonin MT1, MT2, and serotonin 5-HT1 receptors. The corresponding radiotracer [18F]10 demonstrated high brain uptake and extremely high brain-to-blood ratios in biodistribution studies in mice. Pretreatment with the selective σ1 receptor agonist SA4503 significantly reduced the level of accumulation of the radiotracer in the brain. No radiometabolite of [18F]10 was observed to enter the brain. Positron emission tomography and magnetic resonance imaging confirmed suitable kinetics and a high specific binding of [18F]10 to σ1 receptors in rat brain. Ex vivo autoradiography showed a reduced level of binding of [18F]10 in the cortex and hippocampus of the senescence-accelerated prone (SAMP8) compared to that of the senescence-accelerated resistant (SAMR1) mice, indicating the potential dysfunction of σ1 receptors in Alzheimer's disease.
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Affiliation(s)
- Yingfang He
- Key Laboratory of Radiopharmaceuticals (Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University , Beijing, China
| | - Fang Xie
- Key Laboratory of Radiopharmaceuticals (Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University , Beijing, China
| | - Jiajun Ye
- Key Laboratory of Radiopharmaceuticals (Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University , Beijing, China
| | - Winnie Deuther-Conrad
- Helmholtz-Zentrum Dresden-Rossendorf , Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, 04318 Leipzig, Germany
| | - Bixiao Cui
- Department of Nuclear Medicine, Xuanwu Hospital Capital Medical University , Beijing, China
| | - Liang Wang
- Key Laboratory of Radiopharmaceuticals (Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University , Beijing, China
| | - Jie Lu
- Key Laboratory of Radiopharmaceuticals (Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University , Beijing, China
| | - Jörg Steinbach
- Helmholtz-Zentrum Dresden-Rossendorf , Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, 04318 Leipzig, Germany
| | - Peter Brust
- Helmholtz-Zentrum Dresden-Rossendorf , Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, 04318 Leipzig, Germany
| | - Yiyun Huang
- Yale PET Center, Department of Radiology and Biomedical Imaging, Yale University School of Medicine , New Haven, Connecticut 06520-8048, United States
| | - Jie Lu
- Department of Nuclear Medicine, Xuanwu Hospital Capital Medical University , Beijing, China
| | - Hongmei Jia
- Key Laboratory of Radiopharmaceuticals (Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University , Beijing, China
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Chiral resolution of serial potent and selective σ 1 ligands and biological evaluation of (-)-[ 18F]TZ3108 in rodent and the nonhuman primate brain. Bioorg Med Chem 2017; 25:1533-1542. [PMID: 28129990 DOI: 10.1016/j.bmc.2017.01.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 01/11/2017] [Accepted: 01/13/2017] [Indexed: 11/24/2022]
Abstract
Twelve optically pure enantiomers were obtained using either crystallization or chiral high performance liquid chromatography (HPLC) separation methodologies to resolve six racemic sigma-1 (σ1) receptor ligands. The in vitro binding affinities of each enantiomer for σ1, σ2 receptors and vesicular acetylcholine transporter (VAChT) were determined. Out of the 12 optically pure enantiomers, five displayed very high affinities for σ1 (Ki<2nM) and high selectivity for σ1 versus σ2 and VAChT (>100-fold). The minus enantiomer, (-)-14a ((-)-TZ3108) (Ki-σ1=1.8±0.4nM, Ki-σ2=6960±810nM, Ki-VAChT=980±87nM), was chosen for radiolabeling and further in vivo evaluation in rodents and nonhuman primates (NHPs). A biodistribution study in Sprague Dawley rats showed brain uptake (%ID/gram) of (-)-[18F]TZ3108 reached 1.285±0.062 at 5min and 0.802±0.129 at 120min. NHP microPET imaging studies revealed higher brain uptake of (-)-[18F]TZ3108 and more favorable pharmacokinetics compared to its racemic counterpart. Pretreatment of the animal using two structurally different σ1 ligands significantly decreased accumulation of (-)-[18F]TZ3108 in the brain. Together, our in vivo evaluation results suggest that (-)-[18F]TZ3108 is a promising positron emission tomography (PET) tracer for quantifying σ1 receptor in the brain.
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16
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Lever SZ, Fan KH, Lever JR. Tactics for preclinical validation of receptor-binding radiotracers. Nucl Med Biol 2017; 44:4-30. [PMID: 27755986 PMCID: PMC5161541 DOI: 10.1016/j.nucmedbio.2016.08.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2016] [Revised: 08/24/2016] [Accepted: 08/24/2016] [Indexed: 12/20/2022]
Abstract
INTRODUCTION Aspects of radiopharmaceutical development are illustrated through preclinical studies of [125I]-(E)-1-(2-(2,3-dihydrobenzofuran-5-yl)ethyl)-4-(iodoallyl)piperazine ([125I]-E-IA-BF-PE-PIPZE), a radioligand for sigma-1 (σ1) receptors, coupled with examples from the recent literature. Findings are compared to those previously observed for [125I]-(E)-1-(2-(2,3-dimethoxy-5-yl)ethyl)-4-(iodoallyl)piperazine ([125I]-E-IA-DM-PE-PIPZE). METHODS Syntheses of E-IA-BF-PE-PIPZE and [125I]-E-IA-BF-PE-PIPZE were accomplished by standard methods. In vitro receptor binding studies and autoradiography were performed, and binding potential was predicted. Measurements of lipophilicity and protein binding were obtained. In vivo studies were conducted in mice to evaluate radioligand stability, as well as specific binding to σ1 sites in brain, brain regions and peripheral organs in the presence and absence of potential blockers. RESULTS E-IA-BF-PE-PIPZE exhibited high affinity and selectivity for σ1 receptors (Ki = 0.43 ± 0.03 nM, σ2/σ1 = 173). [125I]-E-IA-BF-PE-PIPZE was prepared in good yield and purity, with high specific activity. Radioligand binding provided dissociation (koff) and association (kon) rate constants, along with a measured Kd of 0.24 ± 0.01 nM and Bmax of 472 ± 13 fmol/mg protein. The radioligand proved suitable for quantitative autoradiography in vitro using brain sections. Moderate lipophilicity, Log D7.4 2.69 ± 0.28, was determined, and protein binding was 71 ± 0.3%. In vivo, high initial whole brain uptake, >6% injected dose/g, cleared slowly over 24 h. Specific binding represented 75% to 93% of total binding from 15 min to 24 h. Findings were confirmed and extended by regional brain biodistribution. Radiometabolites were not observed in brain (1%). CONCLUSIONS Substitution of dihydrobenzofuranylethyl for dimethoxyphenethyl increased radioligand affinity for σ1 receptors by 16-fold. While high specific binding to σ1 receptors was observed for both radioligands in vivo, [125I]-E-IA-BF-PE-PIPZE displayed much slower clearance kinetics than [125I]-E-IA-DM-PE-PIPZE. Thus, minor structural modifications of σ1 receptor radioligands lead to major differences in binding properties in vitro and in vivo.
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Affiliation(s)
- Susan Z Lever
- Department of Chemistry, University of Missouri, Columbia, MO, USA; University of Missouri Research Reactor Center, Columbia, MO, USA.
| | - Kuo-Hsien Fan
- Department of Chemistry, University of Missouri, Columbia, MO, USA
| | - John R Lever
- Department of Radiology, University of Missouri, Columbia, MO, USA; Research Service, Harry S. Truman Memorial Veterans' Hospital, Columbia, MO, USA.
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17
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Ramakrishnan NK, Visser AKD, Rybczynska AA, Nyakas CJ, Luiten PGM, Kwizera C, Sijbesma JWA, Elsinga PH, Ishiwata K, Dierckx RAJO, van Waarde A. Sigma-1 Agonist Binding in the Aging Rat Brain: a MicroPET Study with [(11)C]SA4503. Mol Imaging Biol 2016; 18:588-97. [PMID: 26637208 PMCID: PMC4927617 DOI: 10.1007/s11307-015-0917-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
PURPOSE Sigma-1 receptor ligands modulate the release of several neurotransmitters and intracellular calcium signaling. We examined the binding of a radiolabeled sigma-1 agonist in the aging rat brain with positron emission tomography (PET). PROCEDURES Time-dependent uptake of [(11)C]SA4503 was measured in the brain of young (1.5 to 3 months) and aged (18 to 32 months) Wistar Hannover rats, and tracer-kinetic models were fitted to this data, using metabolite-corrected plasma radioactivity as input function. RESULTS In aged animals, the injected probe was less rapidly metabolized and cleared. Logan graphical analysis and a 2-tissue compartment model (2-TCM) fit indicated changes of total distribution volume (V T) and binding potential (BP ND) of the tracer. BP ND was reduced particularly in the (hypo)thalamus, pons, and medulla. CONCLUSIONS Some areas showed reductions of ligand binding with aging whereas binding in other areas (cortex) was not significantly affected.
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Affiliation(s)
- Nisha K Ramakrishnan
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands
- Division of Imaging Sciences and Biomedical Engineering, King's College London, Strand, London, WC2R 2LS, UK
| | - Anniek K D Visser
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands
| | - Anna A Rybczynska
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands
| | - Csaba J Nyakas
- Research Group of Molecular Neurobiology, University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The Netherlands
- Department of Morphology and Physiology, Semmelweis University, 17 Vas, H-1088, Budapest, Hungary
| | - Paul G M Luiten
- Research Group of Molecular Neurobiology, University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The Netherlands
- Department of Morphology and Physiology, Semmelweis University, 17 Vas, H-1088, Budapest, Hungary
| | - Chantal Kwizera
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands
| | - Jurgen W A Sijbesma
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands
| | - Philip H Elsinga
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands
| | - Kiichi Ishiwata
- Southern Tohoku Research Institute for Neuroscience, 7-115 Yatsuyamada, Koriyama, 963-8052, Japan
| | - Rudi A J O Dierckx
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands
| | - Aren van Waarde
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands.
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18
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Xie F, Bergmann R, Kniess T, Deuther-Conrad W, Mamat C, Neuber C, Liu B, Steinbach J, Brust P, Pietzsch J, Jia H. (18)F-Labeled 1,4-Dioxa-8-azaspiro[4.5]decane Derivative: Synthesis and Biological Evaluation of a σ1 Receptor Radioligand with Low Lipophilicity as Potent Tumor Imaging Agent. J Med Chem 2015; 58:5395-407. [PMID: 26090686 DOI: 10.1021/acs.jmedchem.5b00593] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
We report the syntheses and evaluation of series of novel piperidine compounds with low lipophilicity as σ1 receptor ligands. 8-(4-(2-Fluoroethoxy)benzyl)-1,4-dioxa-8-azaspiro[4.5]decane (5a) possessed high affinity (K(i) = 5.4 ± 0.4 nM) for σ1 receptors and selectivity for σ2 receptors (30-fold) and the vesicular acetylcholine transporter (1404-fold). [(18)F]5a was prepared using a one-pot, two-step labeling procedure in an automated synthesis module, with a radiochemical purity of >95%, and a specific activity of 25-45 GBq/μmol. Cellular association, biodistribution, and autoradiography with blocking experiments indicated specific binding of [(18)F]5a to σ1 receptors in vitro and in vivo. Small animal positron emission tomography (PET) imaging using mouse tumor xenograft models demonstrated a high accumulation in human carcinoma and melanoma. Treatment with haloperidol significantly reduced the accumulation of the radiotracer in tumors. These findings suggest that radiotracer with suitable lipophilicity and appropriate affinity for σ1 receptors could be used for tumor imaging.
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Affiliation(s)
- Fang Xie
- †Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, POB 510119, D-01314 Dresden, Germany.,‡Key Laboratory of Radiopharmaceuticals (Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Ralf Bergmann
- †Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, POB 510119, D-01314 Dresden, Germany
| | - Torsten Kniess
- †Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, POB 510119, D-01314 Dresden, Germany
| | - Winnie Deuther-Conrad
- †Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, POB 510119, D-01314 Dresden, Germany
| | - Constantin Mamat
- †Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, POB 510119, D-01314 Dresden, Germany.,§Technische Universität Dresden, Department of Chemistry and Food Chemistry, D-01062 Dresden, Germany
| | - Christin Neuber
- †Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, POB 510119, D-01314 Dresden, Germany
| | - Boli Liu
- ‡Key Laboratory of Radiopharmaceuticals (Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Jörg Steinbach
- †Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, POB 510119, D-01314 Dresden, Germany.,§Technische Universität Dresden, Department of Chemistry and Food Chemistry, D-01062 Dresden, Germany
| | - Peter Brust
- †Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, POB 510119, D-01314 Dresden, Germany
| | - Jens Pietzsch
- †Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, POB 510119, D-01314 Dresden, Germany.,§Technische Universität Dresden, Department of Chemistry and Food Chemistry, D-01062 Dresden, Germany
| | - Hongmei Jia
- ‡Key Laboratory of Radiopharmaceuticals (Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
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Ramakrishnan NK, Visser AKD, Schepers M, Luurtsema G, Nyakas CJ, Elsinga PH, Ishiwata K, Dierckx RAJO, van Waarde A. Dose-dependent sigma-1 receptor occupancy by donepezil in rat brain can be assessed with (11)C-SA4503 and microPET. Psychopharmacology (Berl) 2014; 231:3997-4006. [PMID: 24639047 DOI: 10.1007/s00213-014-3533-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Accepted: 03/04/2014] [Indexed: 12/20/2022]
Abstract
RATIONALE Sigma-1 receptor agonists are under investigation as potential disease-modifying agents for several CNS disorders. Donepezil, an acetylcholinesterase inhibitor used for the symptomatic treatment of Alzheimer's disease, is also a high-affinity sigma-1 agonist. OBJECTIVES The objectives of the present study were to investigate if the sigma-1 agonist tracer (11)C-SA4503 and microPET can be used to determine sigma-1 receptor occupancy (RO) of donepezil in the rat brain; to establish RO of donepezil at doses commonly used in rodent behavioural studies; and to determine the effective plasma concentration of donepezil required for 50 % of max-min occupancy (EC50). METHODS Male Wistar rats were pre-treated with donepezil (0.1 to 10 mg/kg) for about 1 h before microPET scans using (11)C-SA4503. The total distribution volume (V T) of the tracer was determined by Logan graphical analysis using time activity curves from arterial plasma and regions of interest drawn around the entire brain and individual brain regions. RO by donepezil was calculated from a modified Lassen plot, and ED50 was estimated from the sigmoidal dose-response curves obtained when the RO was plotted against log donepezil dose. RESULTS A dose-dependent reduction was observed for V T in the whole brain as well as individual brain regions. RO increased dose-dependently and was 93 % at 10 mg/kg. ED50 was 1.29 mg/kg. CONCLUSIONS Donepezil, in the common dose range, was found to dose-dependently occupy a significant fraction of the sigma-1 receptor population. The data indicate that it is possible to determine sigma-1 RO by an agonist drug in rat brain, using (11)C-SA4503 and microPET.
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Affiliation(s)
- Nisha K Ramakrishnan
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands
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Wang X, Li D, Deuther-Conrad W, Lu J, Xie Y, Jia B, Cui M, Steinbach J, Brust P, Liu B, Jia H. Novel cyclopentadienyl tricarbonyl (99m)tc complexes containing 1-piperonylpiperazine moiety: potential imaging probes for sigma-1 receptors. J Med Chem 2014; 57:7113-25. [PMID: 25073047 DOI: 10.1021/jm5009488] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We report the design, synthesis, and evaluation of a series of novel cyclopentadienyl tricarbonyl (99m)Tc complexes as potent σ1 receptor radioligands. Rhenium compounds 3-(4-(1,3-benzodioxol-5-ylmethyl)piperazin-1-yl)propylcarbonylcyclopentadienyl tricarbonyl rhenium (10a) and 4-(4-(1,3-benzodioxol-5-ylmethyl)piperazin-1-yl)butylcarbonylcyclopentadienyl tricarbonyl rhenium (10b) possessed high in vitro affinity for σ1 receptors and moderate to high selectivity for σ2 receptors and the vesicular acetylcholine transporter. Biodistribution studies in mice demonstrated high initial brain uptake for corresponding (99m)Tc derivatives [(99m)Tc]23 and [(99m)Tc]24 of 2.94 and 2.13% injected dose (ID)/g, respectively, at 2 min postinjection. Pretreatment of haloperidol significantly reduced the radiotracer accumulation of [(99m)Tc]23 or [(99m)Tc]24 in the brain. Studies of the cellular uptake of [(99m)Tc]23 in C6 and DU145 tumor cells demonstrated a reduction of accumulation by incubation with haloperidol, 1-(3,4-dimethoxyphenethyl)-4-(3-phenylpropyl)piperazine (SA4503), or 1,3-di-o-tolyl-guanidine (DTG). Furthermore, blocking studies in C6 glioma-bearing mice confirmed the specific binding of [(99m)Tc]23 to σ1 receptors in the tumor.
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Affiliation(s)
- Xia Wang
- Key Laboratory of Radiopharmaceuticals (Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University , Beijing 100875, China
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21
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Brust P, Deuther-Conrad W, Becker G, Patt M, Donat CK, Stittsworth S, Fischer S, Hiller A, Wenzel B, Dukic-Stefanovic S, Hesse S, Steinbach J, Wünsch B, Lever SZ, Sabri O. Distinctive in vivo kinetics of the new σ1 receptor ligands (R)-(+)- and (S)-(-)-18F-fluspidine in porcine brain. J Nucl Med 2014; 55:1730-6. [PMID: 25071097 DOI: 10.2967/jnumed.114.137562] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
UNLABELLED Because of their involvement in growth and survival signaling cascades, the σ(1) receptors (σ(1)Rs) represent a novel target for the treatment of cancer and several brain diseases such as depression and neurodegeneration. From a series of σ1R-specific (18)F-fluoroalkylated spirocyclic piperidines, we have chosen (18)F-fluspidine for detailed investigation of the in vivo kinetics of the (R)-(+)- and (S)-(-)-enantiomers to identify their potential for imaging in humans. METHODS Enantiopure tosylate precursors for radiolabeling were obtained using chiral preparative high-performance liquid chromatography and used for radiosynthesis of both (18)F-fluspidine enantiomers by nucleophilic substitution with K-(18)F-F-Kryptofix 222-carbonate complex in a synthesis module. Brain pharmacokinetics were investigated by dynamic PET studies in piglets under baseline and blocking conditions using the highly selective σ1R agonist SA4503. Standardized uptake values (SUVs) were calculated for 24 MR-defined brain regions. Total distribution volume (V(T)) and binding potentials (k3'/k4) of (S)-(-)- and (R)-(+)-(18)F-fluspidine were estimated. Furthermore, V(T) values were estimated by graphical analysis using Logan plots. RESULTS The (S)- and (R)-tosylates were obtained in excellent enantiomeric purities (>98% and >96% enantiomeric excess, respectively). (S)-(-)- and (R)-(+)-(18)F-fluspidine were synthesized within approximately 70 min (radiochemical yield, 35%-45%; specific activity, 650-870 GBq/μmol; radiochemical purity, >99%). Both radiotracers displayed different brain uptake kinetics. Although the initial brain uptake was similar, the SUV at the end of the study differed significantly (P < 0.05), with (R)-(+)-(18)F-fluspidine showing about 60%-150% higher values. Administration of SA4503 reduced SUV almost equally for both radiotracers by approximately 65%. Furthermore, k(3)' was significantly decreased under blocking conditions in almost all regions ((S)-(-)-(18)F-fluspidine, -90%-95%; (R)-(+)-(18)F-fluspidine, -70%-90%) whereas effects on k(4) differed according to the particular brain region. V(T) estimated by both graphical analysis using Logan plots and full nonlinear kinetic analysis revealed significant inhibition for both radiotracers under blocking conditions. CONCLUSION Both (S)-(-)- and (R)-(+)-(18)F-fluspidine appear to be suitable for σ1R imaging in humans. The different pharmacokinetics of (S)-(-)-(18)F-fluspidine and (R)-(+)-(18)F-fluspidine may have the potential for application in the diagnostics of different pathologic conditions.
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Affiliation(s)
- Peter Brust
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Leipzig, Germany
| | - Winnie Deuther-Conrad
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Leipzig, Germany
| | - Georg Becker
- Department of Nuclear Medicine and IFB Adiposity Diseases, Universität Leipzig, Leipzig, Germany
| | - Marianne Patt
- Department of Nuclear Medicine and IFB Adiposity Diseases, Universität Leipzig, Leipzig, Germany
| | - Cornelius K Donat
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Leipzig, Germany
| | | | - Steffen Fischer
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Leipzig, Germany
| | - Achim Hiller
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Leipzig, Germany
| | - Barbara Wenzel
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Leipzig, Germany
| | - Sladjana Dukic-Stefanovic
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Leipzig, Germany
| | - Swen Hesse
- Department of Nuclear Medicine and IFB Adiposity Diseases, Universität Leipzig, Leipzig, Germany
| | - Jörg Steinbach
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Leipzig, Germany
| | - Bernhard Wünsch
- Department of Pharmaceutical and Medicinal Chemistry, Westfälische Wilhelms-Universität Münster, Münster, Germany; and
| | - Susan Z Lever
- Department of Chemistry, University of Missouri, Columbia, Missouri MU Research Reactor, University of Missouri, Columbia, Missouri
| | - Osama Sabri
- Department of Nuclear Medicine and IFB Adiposity Diseases, Universität Leipzig, Leipzig, Germany
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22
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Maisonial-Besset A, Funke U, Wenzel B, Fischer S, Holl K, Wünsch B, Steinbach J, Brust P. Automation of the radiosynthesis and purification procedures for [18F]Fluspidine preparation, a new radiotracer for clinical investigations in PET imaging of σ1 receptors in brain. Appl Radiat Isot 2014; 84:1-7. [DOI: 10.1016/j.apradiso.2013.10.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 10/05/2013] [Accepted: 10/26/2013] [Indexed: 10/26/2022]
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Jin H, Fan J, Zhang X, Li J, Flores HP, Perlmutter JS, Parsons SM, Tu Z. Radiosynthesis and in vivo evaluation of a novel σ 1 selective PET ligand. MEDCHEMCOMM 2014; 5:1669-1677. [PMID: 25584182 DOI: 10.1039/c4md00240g] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The σ1 receptor is an important target for CNS disorders. We previously identified a σ1 ligand TZ3108 having highly potent (Ki-σ1 = 0.48 nM) and selective affinity for σ1 versus σ2 receptors. TZ3108 was 18F-labeled with F-18 for in vivo evaluation. Biodistribution and blocking studies of [18F]TZ3108 in male Sprague-Dawley rats demonstrated high brain uptake, which was σ1-specific with no in vivo defluorination. MicroPET studies in cynomolgus macaques showed high brain penetration of [18F]TZ3108; the regional brain distribution was consistent with that of the σ1 receptor. Pseudo-equilibrium in the brain was reached ~ 45 min post-injection. Metabolite analysis of [18F]TZ3108 in NHP blood and rodent blood and brain revealed that ~ 70% parent remained in the plasma of NHPs 60 min post-injection and the major radiometabolite did not cross the blood-brain barrier in rats. In summary, the potent, selective and metabolically stable σ1 specific radioligand [18F]TZ3108 represents a potentially useful PET radioligand for quantifying the σ1 receptor in the brain.
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Affiliation(s)
- Hongjun Jin
- Department of Radiology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Jinda Fan
- Department of Radiology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Xiang Zhang
- Department of Radiology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Junfeng Li
- Department of Radiology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Hubert P Flores
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Joel S Perlmutter
- Department of Radiology, Washington University School of Medicine, St. Louis, MO, 63110, USA. ; Department of Neurology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Stanley M Parsons
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, 93106, USA
| | - Zhude Tu
- Department of Radiology, Washington University School of Medicine, St. Louis, MO, 63110, USA
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Ramakrishnan NK, Rybczynska AA, Visser AKD, Marosi K, Nyakas CJ, Kwizera C, Sijbesma JWA, Elsinga PH, Ishiwata K, Pruim J, Dierckx RAJO, van Waarde A. Small-animal PET with a σ-ligand, 11C-SA4503, detects spontaneous pituitary tumors in aged rats. J Nucl Med 2013; 54:1377-83. [PMID: 23785170 DOI: 10.2967/jnumed.112.115931] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
UNLABELLED Pituitary tumors are often detected only after death or at late stages of the disease when they are macroadenomas with a low surgical cure rate. Spontaneous pituitary tumors occur in rats over 1 y of age. In an ongoing study of changes in σ-1 agonist binding related to aging, several of our rats developed such tumors. The aim of the current study was to assess the kinetics of (11)C-SA4503 ((11)C-labeled 1-[2-(3,4-dimethoxyphenthyl)]-4-(3-phenylpropyl)-piperazine dihydrochloride) in tumor and brain and to evaluate the utility of this tracer in the detection of pituitary tumors. METHODS Small-animal PET scans of the brain region of male Wistar Hannover rats (age, 18-32 mo) were acquired using the σ-1 agonist tracer (11)C-SA4503. The time-dependent uptake of (11)C in the entire brain, tumor or normal pituitary, and thyroid was measured. A 2-tissue-compartment model was fitted to the PET data, using metabolite-corrected plasma radioactivity as the input function. RESULTS Pituitary tumors showed up as bright hot spots in the scans. The total distribution volume (VT) of the tracer was significantly higher in the tumor than in the normal pituitary. Surprisingly, a higher VT was also seen in the brain and thyroid tissue of animals with pituitary tumors than in healthy rats. The increase in VT in the brain and thyroid was not related to a change in nondisplaceable binding potential (BPND) but rather to an increase in the partition coefficient (K1/k2) of (11)C-SA4503. The increase in VT in the tumor on the other hand was accompanied by a significant increase in BPND. Western blotting analysis indicated that pituitary tumors overexpressed σ-1 receptors. CONCLUSION The overexpression of σ-1 receptors in spontaneous pituitary tumors is detected as an increase in uptake and BPND of (11)C-SA4503. Therefore, this tracer may have promise for the detection of pituitary adenomas, using PET.
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Affiliation(s)
- Nisha K Ramakrishnan
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
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Li Y, Wang X, Zhang J, Deuther-Conrad W, Xie F, Zhang X, Liu J, Qiao J, Cui M, Steinbach J, Brust P, Liu B, Jia H. Synthesis and Evaluation of Novel 18F-Labeled Spirocyclic Piperidine Derivatives as σ1 Receptor Ligands for Positron Emission Tomography Imaging. J Med Chem 2013; 56:3478-91. [DOI: 10.1021/jm301734g] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Yan Li
- Key Laboratory
of Radiopharmaceuticals
(Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, People’s
Republic of China
| | - Xia Wang
- Key Laboratory
of Radiopharmaceuticals
(Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, People’s
Republic of China
| | - Jinming Zhang
- Nuclear
Medicine Department, Chinese PLA General Hospital, Beijing 100853, People’s
Republic of China
| | - Winnie Deuther-Conrad
- Helmholtz-Zentrum
Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Research
Site Leipzig, Department of Neuroradiopharmaceuticals, 04318 Leipzig,
Germany
| | - Fang Xie
- Key Laboratory
of Radiopharmaceuticals
(Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, People’s
Republic of China
| | - Xiaojun Zhang
- Nuclear
Medicine Department, Chinese PLA General Hospital, Beijing 100853, People’s
Republic of China
| | - Jian Liu
- Nuclear
Medicine Department, Chinese PLA General Hospital, Beijing 100853, People’s
Republic of China
| | - Jinping Qiao
- Key Laboratory
of Radiopharmaceuticals
(Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, People’s
Republic of China
| | - Mengchao Cui
- Key Laboratory
of Radiopharmaceuticals
(Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, People’s
Republic of China
| | - Jörg Steinbach
- Helmholtz-Zentrum
Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Research
Site Leipzig, Department of Neuroradiopharmaceuticals, 04318 Leipzig,
Germany
| | - Peter Brust
- Helmholtz-Zentrum
Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Research
Site Leipzig, Department of Neuroradiopharmaceuticals, 04318 Leipzig,
Germany
| | - Boli Liu
- Key Laboratory
of Radiopharmaceuticals
(Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, People’s
Republic of China
| | - Hongmei Jia
- Key Laboratory
of Radiopharmaceuticals
(Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, People’s
Republic of China
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Toyohara J, Sakata M, Ishiwata K. Re-evaluation of in vivo selectivity of [11C]SA4503 to σ1 receptors in the brain: Contributions of emopamil binding protein. Nucl Med Biol 2012; 39:1049-52. [DOI: 10.1016/j.nucmedbio.2012.03.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Revised: 03/09/2012] [Accepted: 03/13/2012] [Indexed: 11/29/2022]
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A 96-well filtration method for radioligand binding analysis of σ receptor ligands. J Pharm Biomed Anal 2012; 71:157-61. [PMID: 22910107 DOI: 10.1016/j.jpba.2012.07.023] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Revised: 07/18/2012] [Accepted: 07/22/2012] [Indexed: 11/24/2022]
Abstract
σ receptors represent a potential drug target for numerous therapeutic indications including cancer, depression, psychostimulant abuse, and stroke. Most published radioligand binding studies for σ receptors utilize a low throughput method employing a "cell harvester." Higher throughput methods are required to facilitate efficient screening of large numbers of novel compounds. In this study, a series of reference compounds was analyzed with a new medium-throughput 96-well filtration method and the results were compared to those obtained using the conventional cell harvester-based method. The 96-well assay utilized rat liver membranes for the determination of both known σ receptor subtypes (σ(1) and σ(2)) because this tissue contains high densities of both subtypes and fulfills criteria required for reliable use with the 96-well format. The new method gave comparable K(i) values for reference ligands analyzed in parallel with samples prepared in rat brain membranes and processed on the traditional cell harvester. For σ(1) receptors, equivalent affinity values were observed for both methods/tissues. For σ(2) receptors, approximately 2-fold higher affinities were observed for most compounds in liver, as compared to brain membranes, but excellent correlation with brain-derived values was maintained. To further demonstrate the utility of the new method it was used to screen a novel series of 2(3H)-benzothiazolone compounds, resulting in the identification of several analogues with nanomolar affinity and greater than 50-fold specificity for σ(1) versus σ(2) receptors.
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Abstracts of the Ninth International Symposium on Functional Neuroreceptor Mapping of the Living Brain. August 9-11, 2012. J Cereb Blood Flow Metab 2012; 32 Suppl 1:S13-196. [PMID: 22872875 PMCID: PMC3421080 DOI: 10.1038/jcbfm.2012.77] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Lever SZ, Xu R, Fan KH, Fergason-Cantrell EA, Carmack TL, Watkinson LD, Lever JR. Synthesis, radioiodination and in vitro and in vivo sigma receptor studies of N-1-allyl-N´-4-phenethylpiperazine analogs. Nucl Med Biol 2012; 39:401-14. [PMID: 22172395 DOI: 10.1016/j.nucmedbio.2011.10.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Revised: 08/25/2011] [Accepted: 10/05/2011] [Indexed: 10/14/2022]
Abstract
INTRODUCTION Sigma-1 (σ(1)) receptor radioligands are useful for basic pharmacology studies and for imaging studies in neurology, psychiatry and oncology. We derived a hybrid structure, N-1-allyl-N´-4-phenethylpiperazine, from known ligands TPCNE and SA4503 for use as a scaffold for development of radioiodinated σ(1) receptor ligands. METHODS E-and Z-N-1-(3'-iodoallyl)-N´-4-(3″,4″-dimethoxyphenethyl)-piperazine (E-1 and Z-1), N-1-allyl-N´-4-(3',4'-dimethoxyphenethyl)-piperazine (2) and E-N-1-(3'-iodoallyl)-N´-4-(3″-methoxy-4'´-hydroxyphenethyl)-piperazine (3) were synthesized. Affinities for σ(1) and σ(2) receptors were determined. [(125)I]E-1 and [(125)I]Z-1 were prepared and evaluated in vivo in mice. [(125)I]E-1 was further evaluated in σ(1) receptor binding assays in vitro. RESULTS E-1 displayed moderately high apparent affinity (15 nM) for σ(1) sites and 84-fold selectivity against σ(2) sites. Z-1 showed similar σ(1) affinity, but only 23-fold selectivity. In contrast, 2 exhibited poor binding to both subtypes, while 3 had good affinities but poor selectivity. E-1 profiled as a probable antagonist in the phenytoin shift assay. [(125)I]E-1 and [(125)I]Z-1 were prepared in good yields and with high specific radioactivities. Log D(7.4) values (2.25 and 2.27) fall within the optimal range for in vivo studies. Both radioligands selectively labeled σ(1) receptors in mouse brain and peripheral organs in vivo. [(125)I]E-1 showed a higher level of specific binding than [(125)I]Z-1 and displayed good metabolic stability. Further, [(125)I]E-1 selectively labeled σ(1) receptors in mouse brain homogenates (K(d) 3.79 nM; B(max)=599 fmol/mg protein). CONCLUSIONS [(125)I]E-1 is a selective σ(1) receptor radioligand that exhibits properties amenable to in vitro and in vivo studies, with possible extension to single photon emission computed tomography using iodine-123.
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Affiliation(s)
- Susan Z Lever
- Department of Chemistry, University of Missouri-Columbia, Columbia, MO 65211, USA.
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Mitsuda T, Omi T, Tanimukai H, Sakagami Y, Tagami S, Okochi M, Kudo T, Takeda M. Sigma-1Rs are upregulated via PERK/eIF2α/ATF4 pathway and execute protective function in ER stress. Biochem Biophys Res Commun 2011; 415:519-25. [PMID: 22079628 DOI: 10.1016/j.bbrc.2011.10.113] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Accepted: 10/25/2011] [Indexed: 01/28/2023]
Abstract
Sigma-1 receptors (Sig-1Rs) are the ER resident proteins. Sig-1Rs in the brain have been reported to be significantly reduced in patients with schizophrenia. The impediment of regulating Sig-1Rs expression levels increases the risk for schizophrenia. Thus elucidating the mechanism regulating Sig-1Rs expression might provide the strategy to prevent mental disorders. In this study, we have demonstrated that Sig-1Rs were transcriptionally upregulated by ATF4 in ER stress. Moreover, ATF4 directly bounds to the 5' flanking region of Sig-1R gene. The reporter activities using this region were enhanced in ER stress, or by ATF4 alone. The reporter activities with the pathogenic polymorphisms (GC-241-240TT, T-485A) were reduced. In addition, the processing of Caspase-4 was inhibited by Sig-1Rs. These results indicate that Sig-1Rs are transcriptionally upregulated via the PERK/eIF2α/ATF4 pathway and ameliolate cell death signaling. This study is the first report identifying the transcription factor regulating Sig-1Rs expression.
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Affiliation(s)
- Teruhiko Mitsuda
- Psychiatry, Department of Integrated Medicine, Division of Internal Medicine, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan.
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Ishiwata K, Kimura Y, Oda K, Ishii K, Sakata M, Kawasaki K, Nariai T, Suzuki Y, Ishibashi K, Mishina M, Hashimoto M, Ishikawa M, Toyohara J. Development of PET radiopharmaceuticals and their clinical applications at the Positron Medical Center. Geriatr Gerontol Int 2010; 10 Suppl 1:S180-96. [PMID: 20590833 DOI: 10.1111/j.1447-0594.2010.00594.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The Positron Medical Center has developed a large number of radiopharmaceuticals and 36 radiopharmaceuticals have been approved for clinical use for studying aging and geriatric diseases, especially brain functions. Positron emission tomography (PET) has been used to provide a highly advanced PET-based diagnosis. The current status of the development of radiopharmaceuticals, and representative clinical and methodological results are reviewed.
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Affiliation(s)
- Kiichi Ishiwata
- Positron Medical Center, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan.
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High occupancy of sigma1 receptors in the human brain after single oral administration of donepezil: a positron emission tomography study using [11C]SA4503. Int J Neuropsychopharmacol 2009; 12:1127-31. [PMID: 19573265 DOI: 10.1017/s1461145709990204] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The acetylcholinesterase (AChE) inhibitor donepezil is also a sigma1 receptor agonist. We examined whether donepezil binds to sigma1 receptors in the living human brain after a single oral administration. Dynamic positron emission tomography (PET) data acquisition using the selective sigma1 receptor ligand [11C]SA4503 was performed to evaluate quantitatively the binding of [11C]SA4503 to sigma1 receptors in eight healthy male volunteers. Each subject had a PET scan before and after receiving a single dose of donepezil (5 or 10 mg). The binding potential of [11C]SA4503 was calculated. Doses of 5 mg and 10 mg donepezil bound to sigma1 receptors in the human brain with occupancies of approximately 60% and approximately 75%, respectively, in a dose-dependent manner. This study demonstrated that donepezil binds to sigma1 receptors in the living human brain at therapeutic doses. Therefore, sigma1 receptors may be implicated in the pharmacological mechanism of donepezil in the human brain.
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Hiraoka K, Okamura N, Funaki Y, Watanuki S, Tashiro M, Kato M, Hayashi A, Hosokai Y, Yamasaki H, Fujii T, Mori E, Yanai K, Watabe H. Quantitative analysis of donepezil binding to acetylcholinesterase using positron emission tomography and [5-(11)C-methoxy]donepezil. Neuroimage 2009; 46:616-23. [PMID: 19286462 DOI: 10.1016/j.neuroimage.2009.03.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2008] [Revised: 02/24/2009] [Accepted: 03/04/2009] [Indexed: 11/16/2022] Open
Abstract
The aim of this study was to establish kinetic analysis of [5-(11)C-methoxy]donepezil ([(11)C]donepezil), which was developed for the in-vivo visualization of donepezil binding to acetylcholinesterase (AChE) using positron emission tomography (PET). Donepezil is an AChE inhibitor that is widely prescribed to ameliorate the cognitive impairment of patients with dementia. Six healthy subjects took part in a dynamic study involving a 60-min PET scan after intravenous injection of [(11)C]donepezil. The total distribution volume (tDV) of [(11)C]donepezil was quantified by compartmental kinetic analysis and Logan graphical analysis. A one-tissue compartment model (1TCM) and a two-tissue compartment model (2TCM) were applied in the kinetic analysis. Goodness of fit was assessed with chi(2) criterion and Akaike's Information Criterion (AIC). Compared with a 1TCM, goodness of fit was significantly improved by a 2TCM. The tDVs provided by Logan graphical analysis were slightly lower than those provided by a 2TCM. The rank order of the mean tDVs in 10 regions was in line with the AChE activity reported in a previous post-mortem study. Logan graphical analysis generated voxel-wise images of tDV, revealing the overall distribution pattern of AChE in individual brains. Significant correlation was observed between tDVs calculated with and without metabolite correction for plasma time-activity curves, indicating that metabolite correction could be omitted. In conclusion, this method enables quantitative analysis of AChE and direct investigation of the pharmacokinetics of donepezil in the human brain.
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Affiliation(s)
- Kotaro Hiraoka
- Department of Behavioral Neurology and Cognitive Neuroscience, Tohoku University Graduate School of Medicine, 2-1, Seiryo-machi, Aoba-ku, Sendai, 980-8575, Japan.
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Rybczynska AA, Elsinga PH, Sijbesma JW, Ishiwata K, de Jong JR, de Vries EF, Dierckx RA, van Waarde A. Steroid hormones affect binding of the sigma ligand 11C-SA4503 in tumour cells and tumour-bearing rats. Eur J Nucl Med Mol Imaging 2009; 36:1167-75. [PMID: 19247652 PMCID: PMC2691528 DOI: 10.1007/s00259-009-1076-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2008] [Accepted: 01/16/2009] [Indexed: 11/28/2022]
Abstract
Purpose Sigma receptors are implicated in memory and cognitive functions, drug addiction, depression and schizophrenia. In addition, sigma receptors are strongly overexpressed in many tumours. Although the natural ligands are still unknown, steroid hormones are potential candidates. Here, we examined changes in binding of the sigma-1 agonist 11C-SA4503 in C6 glioma cells and in living rats after modification of endogenous steroid levels. Methods 11C-SA4503 binding was assessed in C6 monolayers by gamma counting and in anaesthetized rats by microPET scanning. C6 cells were either repeatedly washed and incubated in steroid-free medium or exposed to five kinds of exogenous steroids (1 h or 5 min before tracer addition, respectively). Tumour-bearing male rats were repeatedly treated with pentobarbital (a condition known to result in reduction of endogenous steroid levels) or injected with progesterone. Results Binding of 11C-SA4503 to C6 cells was increased (~50%) upon removal and decreased (~60%) upon addition of steroid hormones (rank order of potency: progesterone > allopregnanolone = testosterone = androstanolone > dehydroepiandrosterone-3-sulphate, IC50 progesterone 33 nM). Intraperitoneally administered progesterone reduced tumour uptake and tumour-to-muscle contrast (36%). Repeated treatment of animals with pentobarbital increased the PET standardized uptake value of 11C-SA4503 in tumour (16%) and brain (27%), whereas the kinetics of blood pool radioactivity was unaffected. Conclusions The binding of 11C-SA4503 is sensitive to steroid competition. Since not only increases but also decreases of steroid levels affect ligand binding, a considerable fraction of the sigma-1 receptor population in cultured tumour cells or tumour-bearing animals is normally occupied by endogenous steroids.
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Affiliation(s)
- Anna A Rybczynska
- Nuclear Medicine and Molecular Imaging, University of Groningen Medical Center, University of Groningen, Hanzeplein 1, 9713GZ, Groningen, The Netherlands.
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Shidahara M, Seki C, Naganawa M, Sakata M, Ishikawa M, Ito H, Kanno I, Ishiwata K, Kimura Y. Improvement of likelihood estimation in Logan graphical analysis using maximum a posteriori for neuroreceptor PET imaging. Ann Nucl Med 2009; 23:163-71. [PMID: 19225940 DOI: 10.1007/s12149-008-0226-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2008] [Accepted: 11/16/2008] [Indexed: 11/25/2022]
Abstract
OBJECTIVE To reduce variance of the total volume of distribution (V (T)) image, we improved likelihood estimation in graphical analysis (LEGA) for dynamic positron emission tomography (PET) images using maximum a posteriori (MAP). METHODS In our proposed MAP estimation in graphical analysis (MEGA), a set of time-activity curves (TACs) was formed with V (T) varying in physiological range as a template, and then the most similar TAC was sought out for a given measured TAC in a feature space. In simulation, MEGA was compared with other three methods, Logan graphical analysis (GA), multilinear analysis (MA1), and LEGA using 500 noisy TACs, under each of seven physiological conditions (from 9.9 to 61.5 of V (T)). PET studies of [(11)C]SA4503 were performed in three healthy volunteers. In clinical studies, the V (T) images estimated from MEGA were compared with region of interest (ROI) estimates from a nonlinear least square (NLS) fitting over four brain regions. RESULTS In the simulation study, the estimated V (T) by GA had a large underestimation (y = 0.27x + 8.72, r (2) = 0.87). Applying the other methods (MA1, LEGA, and MEGA), these noise-induced biases were improved (y = 0.80x + 4.04, r (2) = 0.98; y = 0.85x + 3.05, r (2) = 0.99; y = 0.96x + 1.21, r (2) = 0.99, respectively). MA1 and LEGA produced increased variance of the estimated V (T) in clinical studies. However, MEGA improved signal-to-noise ratio (SNR) in V (T) images with linear correlations between ROI estimates with NLS (y = 0.87x + 5.1, r (2) = 0.96). CONCLUSIONS MEGA was validated as an alternative strategy of LEGA to improve estimates of V (T) in clinical PET imaging.
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Affiliation(s)
- Miho Shidahara
- National Institute of Radiological Sciences, Molecular Imaging Center, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan.
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Successive positron emission tomography measurement of cerebral blood flow and neuroreceptors in the human brain: an 11C-SA4503 study. Ann Nucl Med 2008; 22:411-6. [PMID: 18600419 DOI: 10.1007/s12149-008-0133-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2007] [Accepted: 02/17/2008] [Indexed: 10/21/2022]
Abstract
For evaluating a newly developed radioligand for positron emission tomography (PET), successive measurements of regional cerebral blood flow (rCBF) and the kinetics of the radioligand in the same subject are preferable in the first clinical trial. In this study, we demonstrate an example for the study of (11)C-labeled 1-(3,4-dimethoxyphenethyl)-4-(3-phenylprophyl) piperazine ((11)C-SA4503) for mapping sigma(1) receptors in the human brain. Five healthy male subjects underwent two successive PET scans with (15)O-H(2)O to measure the rCBF and with (11)C-SA4503 (dynamic 60-min scan). The brain kinetics of (11)C-SA4503 was evaluated using the time-activity curve (TAC) of tissue in each of the 11 regions of the brain and the metabolite-corrected TAC of plasma on the basis of a two-tissue compartment fourparameter model. The estimated parameters were four rate constants: K (1), influx from plasma to brain tissue; k (2), efflux from tissue to plasma; k (3), association between tracer and receptors; and k (4), dissociation of tracer-receptor complex, and the binding potential (BP), k (3)/k (4). (11)CSA4503 was distributed all over the brain, and the TACs exhibited an accumulation pattern in all the 11 regions. K (1) of (11)C-SA4503 correlated with rCBF, but the other three rate constant parameters and BP did not. The regional difference in the BP of (11)C-SA4503 is compatible with those of sigma(1) receptors. In conclusion, successive PET measurements of rCBF and the brain kinetics of radioligand-neuroreceptor binding are useful for the first clinical trial of a newly developed radioligand for mapping neuroreceptors, and the protocol is applicable to pathophysiological studies of brain disorders.
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Mishina M, Ohyama M, Ishii K, Kitamura S, Kimura Y, Oda KI, Kawamura K, Sasaki T, Kobayashi S, Katayama Y, Ishiwata K. Low density of sigma1 receptors in early Alzheimer’s disease. Ann Nucl Med 2008; 22:151-6. [DOI: 10.1007/s12149-007-0094-z] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2007] [Accepted: 09/05/2007] [Indexed: 10/22/2022]
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Shortened protocol in practical [11C]SA4503-PET studies for sigma1 receptor quantification. Ann Nucl Med 2008; 22:143-6. [PMID: 18311540 DOI: 10.1007/s12149-007-0088-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2007] [Accepted: 10/09/2007] [Indexed: 10/22/2022]
Abstract
In practical positron emission tomography (PET) diagnosis, a shortened protocol is preferred for patients with brain disorders. In this study, the applicability of a shortened protocol as an alternative to the 90-min PET scan with [(11)C]SA4503 for quantitative sigma(1) receptor measurement was investigated. Tissue time-activity curves of 288 regions of interest in the brain from 32 [(11)C]SA4503-PET scans of 16 healthy subjects prior to and following administration of a selective serotonin reuptake inhibitor (fluvoxamine or paroxetine) were applied to two algorithms of quantitative analysis; binding potential (BP) was derived from compartmental analysis based on nonlinear estimation, and total distribution volume (tDV) was derived from Logan plot analysis. As a result, although both BP and tDV tended to be underestimated by the shortened method, the estimates from the shortened protocol had good linear relationships with those of the full-length protocol. In conclusion, if approximately 10% differences in the estimated results are acceptable for a specific purpose, then a 60-min measurement protocol is capable of providing reliable results.
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Hayashi T, Su TP. An update on the development of drugs for neuropsychiatric disorders: focusing on the sigma 1 receptor ligand. Expert Opin Ther Targets 2008; 12:45-58. [PMID: 18076369 DOI: 10.1517/14728222.12.1.45] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The sigma1 receptor is an intracellular molecule that shares no homology with any mammalian proteins. sigma1 receptors normally localize at the endoplasmic reticulum and regulate a variety of signal transductions including intracellular Ca2+ dynamics and neurotrophic factor signaling. In the brain, sigma1 receptors are known to regulate the activity of diverse ion channels via protein-protein interactions. Accumulated evidences strongly indicate that the activation/upregulation of sigma1 receptors promotes the neuronal differentiation as well as a robust antiapoptotic action. In animals, sigma1 receptor agonists exhibit an antidepressant-like action. Furthermore, the agonists enhanced neuronal survival eventhough they were administered several hours after a brain ischemia. Thus, primary clinical targets of sigma1 receptor ligands are proposed to include stroke, neurodegenerative disorders and depression. Ligands for the sigma1 receptor may constitute a new class of therapeutic drugs targeting an endoplasmic reticular protein.
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Affiliation(s)
- Teruo Hayashi
- IRP, NIDA-NIH, Cellular Pathobiology Unit, Development and Plasticity Section, Cellular Neurobiology Research Branch, Room 3418, Triad building, 333 Cassell Drive, Baltimore, MD 21224, USA.
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Affiliation(s)
- Masahiro Mishina
- Department of Neurological, Nephrological and Rheumatological Science, Graduate School of Medicine, Nippon Medical School
- Neurological Institute, Nippon Medical School Chiba Hokusoh Hospital
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Okamura N, Funaki Y, Tashiro M, Kato M, Ishikawa Y, Maruyama M, Ishikawa H, Meguro K, Iwata R, Yanai K. In vivo visualization of donepezil binding in the brain of patients with Alzheimer's disease. Br J Clin Pharmacol 2007; 65:472-9. [PMID: 18070217 DOI: 10.1111/j.1365-2125.2007.03063.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT * Deficit in central cholinergic neurotransmission is a consistent change associated with Alzheimer's disease (AD). * Donepezil hydrochloride exhibits selective inhibition of acetylcholinesterase (AChE) and is widely used for the treatment of AD. * The biodistribution of donepezil in the brain after administration is not precisely understood in vivo. * There is no method to measure the amount of binding of orally administered donepezil to AChE. WHAT THIS STUDY ADDS * This study clearly visualizes the distribution of donepezil in human brain using [(11)C]-donepezil and positron emission tomography. * This study demonstrates prominent reduction of the donepezil binding site in the AD brain. * This study provides methodology to measure the AChE binding occupancy of orally administered donepezil and provides a new surrogate marker for evaluation and prediction of response to donepezil treatment. AIMS The aims of this study were to visualize in vivo binding of donepezil to acetylcholinesterase (AChE) in the brain and to establish a method for measuring the amount of binding of orally administered donepezil. METHODS [5-(11)C-methoxy]-donepezil ([(11)C]-donepezil) was radiolabelled as a positron emission tomography (PET) tracer. The biodistribution of [(11)C]-donepezil was measured by PET in 10 AD patients and six elderly normal subjects. Two AD patients underwent additional PET measurements after oral administration of donepezil for 6 months. RESULTS [(11)C]-donepezil-PET images demonstrated high densities of tracer distribution in AChE-rich brain regions such as the striatum, thalamus, and cerebellum. Compared with elderly normal subjects, patients with mild AD exhibited about 18-20% reduction of donepezil binding in the neocortex and hippocampus, while patients with moderate AD exhibited about 24-30% reduction of donepezil binding throughout the brain. Orally administered donepezil (5 mg day(-1)) induced 61.6-63.3% reduction of donepezil binding in AD brains. The distribution volume of [(11)C]-donepezil in the hippocampus was significantly correlated with MMSE scores in AD patients. CONCLUSIONS [(11)C]-donepezil-PET enables quantitative measurement of donepezil binding in the brain. AD patients exhibited reduction of donepezil binding in the brain, even in the early stage of disease. Longitudinal evaluation by this technique enables determination of AChE binding occupancy of orally administered donepezil.
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Affiliation(s)
- Nobuyuki Okamura
- Department of Pharmacology, Tohoku University Graduate School of Medicine, Sendai, Japan.
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Distribution volume as an alternative to the binding potential for sigma1 receptor imaging. Ann Nucl Med 2007; 21:533-5. [DOI: 10.1007/s12149-007-0063-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2007] [Accepted: 06/20/2007] [Indexed: 10/22/2022]
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Ishikawa M, Ishiwata K, Ishii K, Kimura Y, Sakata M, Naganawa M, Oda K, Miyatake R, Fujisaki M, Shimizu E, Shirayama Y, Iyo M, Hashimoto K. High occupancy of sigma-1 receptors in the human brain after single oral administration of fluvoxamine: a positron emission tomography study using [11C]SA4503. Biol Psychiatry 2007; 62:878-83. [PMID: 17662961 DOI: 10.1016/j.biopsych.2007.04.001] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2007] [Revised: 03/31/2007] [Accepted: 04/02/2007] [Indexed: 11/24/2022]
Abstract
BACKGROUND Sigma-1 receptors might be implicated in the pathophysiology of psychiatric diseases, as well as in the mechanisms of action of some selective serotonin reuptake inhibitors (SSRIs). Among the several SSRIs, fluvoxamine has the highest affinity for sigma-1 receptors (Ki = 36 nM), whereas paroxetine shows low affinity (Ki = 1893 nM). The present study was undertaken to examine whether fluvoxamine binds to sigma-1 receptors in living human brain. METHODS A dynamic positron emission tomography (PET) data acquisition using the selective sigma-1 receptor ligand [(11)C]SA4503 was performed with arterial blood sampling to evaluate quantitatively the binding of [(11)C]SA4503 to sigma-1 receptors in 15 healthy male volunteers. Each subject had two PET scans before and after randomly receiving a single dose of either fluvoxamine (50, 100, 150, or 200 mg) or paroxetine (20 mg). The binding potential of [(11)C]SA4503 in 9 regions of the brain was calculated by a 2-tissue 3-compartment model. In addition, we examined the effects of functional polymorphisms of the sigma-1 receptor (SIGMAR1) gene on the binding potential of [(11)C]SA4503. RESULTS Fluvoxamine bound to sigma-1 receptors in all brain regions in a dose-dependent manner, whereas paroxetine did not bind to sigma-1 receptors. However, there was no association between the SIGMAR1 gene polymorphism GC-241-240TT and binding potential. CONCLUSIONS The study demonstrated that fluvoxamine bound to sigma-1 receptors in living human brain at therapeutic doses. These findings suggest that sigma-1 receptors may play an important role in the mechanism of action of fluvoxamine.
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Affiliation(s)
- Masatomo Ishikawa
- Division of Clinical Neuroscience, Chiba University Center for Forensic Mental Health, Chiba, Japan
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Shidahara M, Ikoma Y, Kershaw J, Kimura Y, Naganawa M, Watabe H. PET kinetic analysis: wavelet denoising of dynamic PET data with application to parametric imaging. Ann Nucl Med 2007; 21:379-86. [PMID: 17876550 DOI: 10.1007/s12149-007-0044-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2007] [Accepted: 05/14/2007] [Indexed: 11/28/2022]
Abstract
Physiological functions (e.g., cerebral blood flow, glucose metabolism, and neuroreceptor binding) can be investigated as parameters estimated by kinetic modeling using dynamic positron emission tomography (PET) images. Imaging of these physiological parameters, called parametric imaging, can locate the regional distribution of functionalities. However, the most serious technical issue affecting parametric imaging is noise in dynamic PET data. This review describes wavelet denoising of dynamic PET images for improving image quality in estimated parametric images. Wavelet denoising provides significantly improved quality directly to dynamic PET images and indirectly to estimated parametric images. The application of wavelet denoising to radio-ligand and kinetic analysis is still in the development stage, but even so, it is thought that wavelet techniques will have a substantial impact on nuclear medicine in the near future.
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Affiliation(s)
- Miho Shidahara
- Biophysics Group, Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Chiba 263-8555, Japan.
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Kimura Y, Naganawa M, Shidahara M, Ikoma Y, Watabe H. PET kinetic analysis —Pitfalls and a solution for the Logan plot. Ann Nucl Med 2007; 21:1-8. [PMID: 17373330 DOI: 10.1007/bf03033993] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The Logan plot is a widely used algorithm for the quantitative analysis of neuroreceptors using PET because it is easy to use and simple to implement. The Logan plot is also suitable for receptor imaging because its algorithm is fast. However, use of the Logan plot, and interpretation of the formed receptor images should be regarded with caution, because noise in PET data causes bias in the Logan plot estimates. In this paper, we describe the basic concept of the Logan plot in detail and introduce three algorithms for the Logan plot. By comparing these algorithms, we demonstrate the pitfalls of the Logan plot and discuss the solution.
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Affiliation(s)
- Yuichi Kimura
- Positron Medical Center, Tokyo Metropolitan Institute of Gerontology, 1-1, Naka, Itabashi, Tokyo 173-0022, Japan.
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