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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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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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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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Fuchigami T, Yamaguchi H, Ogawa M, Biao L, Nakayama M, Haratake M, Magata Y. Synthesis and biological evaluation of radio-iodinated benzimidazoles as SPECT imaging agents for NR2B subtype of NMDA receptor. Bioorg Med Chem 2010; 18:7497-506. [DOI: 10.1016/j.bmc.2010.08.053] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Revised: 08/27/2010] [Accepted: 08/28/2010] [Indexed: 10/19/2022]
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Hirata M, Mori T, Umeda T, Abe T, Yamamoto T, Ohmomo Y. Evaluation of Radioiodinated 1-[2-(3,4-Dimethoxyphenyl)ethyl]-4-(2-iodophenylpropyl)piperazine as a Tumor Diagnostic Agent with Functional Sigma Receptor Imaging by Single Photon Emission Computed Tomography. Biol Pharm Bull 2008; 31:879-83. [DOI: 10.1248/bpb.31.879] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Hirata M, Mori T, Soga S, Umeda T, Ohmomo Y. In Vivo Evaluation of Radioiodinated 1-[2-(3,4-Dimethoxyphenyl)ethyl]-4-(3-phenylpropyl)-piperazine Derivatives as New Ligands for Sigma Receptor Imaging Using Single Photon Emission Computed Tomography. Biol Pharm Bull 2006; 29:2009-15. [PMID: 17015942 DOI: 10.1248/bpb.29.2009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
New series of radioiodinated analogues of 1-[2-(3,4-dimethoxyphenyl)ethyl]-4-[3-(2-iodophenyl)propyl]piperazine (o-BON) and 1-[2-(3,4-dimethoxyphenyl)ethyl]-4-[3-(3-iodophenyl)propyl]piperazine (m-BON) were evaluated as single photon emission computed tomography (SPECT) radiopharmaceuticals for mapping sigma receptors in the central nervous system (CNS) and peripheral organs. In vivo biodistribution studies of [125I] o- and m-BON in mice demonstrated high initial uptakes and prolonged retention in the brain. In contrast to high brain uptake and retention, the blood accumulations were low, resulting in good brain-blood ratios (7.9-9.2). In the other tissues, high uptake of [125I] o- and m-BON were observed in the liver, kidney, heart, lung, and pancreas. Moreover, selective interactions of [125I] o- and m-BON with sigma receptors were confirmed by pretreatment experiments with various sigma and other receptor ligands. Haloperidol posttreatment induced decreases in the accumulation of [125I] o- and m-BON. These data suggest that [125I] o- and m-BON binding to sigma receptors is reversible and competitive. Furthermore, ex vivo autoradiograms of [125I] o- and m-BON in rats showed high uptake in the parietal cortex, vestibular nucleus, and pons nucleus and moderate uptake in the thalamus, inferior colliculus, hippocampus, hypothalamus, and temporal cortex. These ex vivo autoradiograms were comparable with the histochemical distribution of sigma receptors. Furthermore, the uptake of [125I] o- and m-BON reflected quantitative amounts of sigma receptor in the brain. These results demonstrated that radiolabeled o- and m-BON have good characteristics for mapping sigma receptors in the CNS and the peripheral organs with SPECT.
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Affiliation(s)
- Masahiko Hirata
- Osaka University of Pharmaceutical Sciences, Nasahara, Osaka, Japan
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