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Buccellato FR, D’Anca M, Tartaglia GM, Del Fabbro M, Scarpini E, Galimberti D. Treatment of Alzheimer's Disease: Beyond Symptomatic Therapies. Int J Mol Sci 2023; 24:13900. [PMID: 37762203 PMCID: PMC10531090 DOI: 10.3390/ijms241813900] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 09/05/2023] [Accepted: 09/07/2023] [Indexed: 09/29/2023] Open
Abstract
In an ever-increasing aged world, Alzheimer's disease (AD) represents the first cause of dementia and one of the first chronic diseases in elderly people. With 55 million people affected, the WHO considers AD to be a disease with public priority. Unfortunately, there are no final cures for this pathology. Treatment strategies are aimed to mitigate symptoms, i.e., acetylcholinesterase inhibitors (AChEI) and the N-Methyl-D-aspartate (NMDA) antagonist Memantine. At present, the best approaches for managing the disease seem to combine pharmacological and non-pharmacological therapies to stimulate cognitive reserve. Over the last twenty years, a number of drugs have been discovered acting on the well-established biological hallmarks of AD, deposition of β-amyloid aggregates and accumulation of hyperphosphorylated tau protein in cells. Although previous efforts disappointed expectations, a new era in treating AD has been working its way recently. The Food and Drug Administration (FDA) gave conditional approval of the first disease-modifying therapy (DMT) for the treatment of AD, aducanumab, a monoclonal antibody (mAb) designed against Aβ plaques and oligomers in 2021, and in January 2023, the FDA granted accelerated approval for a second monoclonal antibody, Lecanemab. This review describes ongoing clinical trials with DMTs and non-pharmacological therapies. We will also present a future scenario based on new biomarkers that can detect AD in preclinical or prodromal stages, identify people at risk of developing AD, and allow an early and curative treatment.
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Affiliation(s)
- Francesca R. Buccellato
- Department of Biomedical, Surgical and Dental Sciences, University of Milan, 20122 Milan, Italy
- Fondazione IRCCS Ca’ Granda, Ospedale Maggiore Policlinico, 20122 Milan, Italy
| | - Marianna D’Anca
- Fondazione IRCCS Ca’ Granda, Ospedale Maggiore Policlinico, 20122 Milan, Italy
| | - Gianluca Martino Tartaglia
- Department of Biomedical, Surgical and Dental Sciences, University of Milan, 20122 Milan, Italy
- Fondazione IRCCS Ca’ Granda, Ospedale Maggiore Policlinico, 20122 Milan, Italy
| | - Massimo Del Fabbro
- Department of Biomedical, Surgical and Dental Sciences, University of Milan, 20122 Milan, Italy
- Fondazione IRCCS Ca’ Granda, Ospedale Maggiore Policlinico, 20122 Milan, Italy
| | - Elio Scarpini
- Fondazione IRCCS Ca’ Granda, Ospedale Maggiore Policlinico, 20122 Milan, Italy
| | - Daniela Galimberti
- Department of Biomedical, Surgical and Dental Sciences, University of Milan, 20122 Milan, Italy
- Fondazione IRCCS Ca’ Granda, Ospedale Maggiore Policlinico, 20122 Milan, Italy
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Malar DS, Thitilertdecha P, Ruckvongacheep KS, Brimson S, Tencomnao T, Brimson JM. Targeting Sigma Receptors for the Treatment of Neurodegenerative and Neurodevelopmental Disorders. CNS Drugs 2023; 37:399-440. [PMID: 37166702 PMCID: PMC10173947 DOI: 10.1007/s40263-023-01007-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 04/18/2023] [Indexed: 05/12/2023]
Abstract
The sigma-1 receptor is a 223 amino acid-long protein with a recently identified structure. The sigma-2 receptor is a genetically unrelated protein with a similarly shaped binding pocket and acts to influence cellular activities similar to the sigma-1 receptor. Both proteins are highly expressed in neuronal tissues. As such, they have become targets for treating neurological diseases, including Alzheimer's disease (AD), Huntington's disease (HD), Parkinson's disease (PD), multiple sclerosis (MS), Rett syndrome (RS), developmental and epileptic encephalopathies (DEE), and motor neuron disease/amyotrophic lateral sclerosis (MND/ALS). In recent years, there have been many pre-clinical and clinical studies of sigma receptor (1 and 2) ligands for treating neurological disease. Drugs such as blarcamesine, dextromethorphan and pridopidine, which have sigma-1 receptor activity as part of their pharmacological profile, are effective in treating multiple aspects of several neurological diseases. Furthermore, several sigma-2 receptor ligands are under investigation, including CT1812, rivastigmine and SAS0132. This review aims to provide a current and up-to-date analysis of the current clinical and pre-clinical data of drugs with sigma receptor activities for treating neurological disease.
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Affiliation(s)
- Dicson S Malar
- Natural Products for Neuroprotection and Anti-ageing Research Unit, Chulalongkorn University, Bangkok, Thailand
| | - Premrutai Thitilertdecha
- Siriraj Research Group in Immunobiology and Therapeutic Sciences, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Kanokphorn S Ruckvongacheep
- Department of Clinical Microscopy, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok, Thailand
| | - Sirikalaya Brimson
- Department of Clinical Microscopy, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok, Thailand
| | - Tewin Tencomnao
- Natural Products for Neuroprotection and Anti-ageing Research Unit, Chulalongkorn University, Bangkok, Thailand
| | - James M Brimson
- Natural Products for Neuroprotection and Anti-ageing Research Unit, Chulalongkorn University, Bangkok, Thailand.
- Research, Innovation and International Affairs, Faculty of Allied Health Sciences, Chulalongkorn University, Room 409, ChulaPat-1 Building, 154 Rama 1 Road, Bangkok, 10330, Thailand.
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3
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Abstract
The serotonin (5-hydroxytryptamine, 5-HT) 2A receptor is most well known as the common target for classic psychedelic compounds. Interestingly, the 5-HT2A receptor is the most widely expressed mammalian serotonin receptor and is found in nearly every examined tissue type including neural, endocrine, endothelial, immune, and muscle, suggesting it could be a novel and pharmacological target for several types of disorders. Despite this, the bulk of research on the 5-HT2A receptor is focused on its role in the central nervous system (CNS). Recently, activation of 5-HT2A receptors has emerged as a new anti-inflammatory strategy. This review will describe recent findings regarding psychedelics as anti-inflammatory compounds, as well as parse out differences in functional selectivity and immune regulation that exist between a number of well-known hallucinogenic compounds.
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Affiliation(s)
- Thomas W Flanagan
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, New Orleans, LA, USA
| | - Charles D Nichols
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, New Orleans, LA, USA.
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Lepelletier FX, Vandesquille M, Asselin MC, Prenant C, Robinson AC, Mann DMA, Green M, Barnett E, Banister SD, Mottinelli M, Mesangeau C, McCurdy CR, Fricke IB, Jacobs AH, Kassiou M, Boutin H. Evaluation of 18F-IAM6067 as a sigma-1 receptor PET tracer for neurodegeneration in vivo in rodents and in human tissue. Theranostics 2020; 10:7938-7955. [PMID: 32724451 PMCID: PMC7381740 DOI: 10.7150/thno.47585] [Citation(s) in RCA: 4] [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] [Received: 04/29/2020] [Accepted: 06/06/2020] [Indexed: 01/30/2023] Open
Abstract
The sigma 1 receptor (S1R) is widely expressed in the CNS and is mainly located on the endoplasmic reticulum. The S1R is involved in the regulation of many neurotransmission systems and, indirectly, in neurodegenerative diseases. The S1R may therefore represent an interesting neuronal biomarker in neurodegenerative diseases such as Parkinson's (PD) or Alzheimer's diseases (AD). Here we present the characterisation of the S1R-specific 18F-labelled tracer 18F-IAM6067 in two animal models and in human brain tissue. Methods: Wistar rats were used for PET-CT imaging (60 min dynamic acquisition) and metabolite analysis (1, 2, 5, 10, 20, 60 min post-injection). To verify in vivo selectivity, haloperidol, BD1047 (S1R ligand), CM398 (S2R ligand) and SB206553 (5HT2B/C antagonist) were administrated for pre-saturation studies. Excitotoxic lesions induced by intra-striatal injection of AMPA were also imaged by 18F-IAM6067 PET-CT to test the sensitivity of the methods in a well-established model of neuronal loss. Tracer brain uptake was also verified by autoradiography in rats and in a mouse model of PD (intrastriatal 6-hydroxydopamine (6-OHDA) unilateral lesion). Finally, human cortical binding was investigated by autoradiography in three groups of subjects (control subjects with Braak ≤2, and AD patients, Braak >2 & ≤4 and Braak >4 stages). Results: We demonstrate that despite rapid peripheral metabolism of 18F-IAM6067, radiolabelled metabolites were hardly detected in brain samples. Brain uptake of 18F-IAM6067 showed differences in S1R anatomical distribution, namely from high to low uptake: pons-raphe, thalamus medio-dorsal, substantia nigra, hypothalamus, cerebellum, cortical areas and striatum. Pre-saturation studies showed 79-90% blockade of the binding in all areas of the brain indicated above except with the 5HT2B/C antagonist SB206553 and S2R ligand CM398 which induced no significant blockade, indicating good specificity of 18F-IAM6067 for S1Rs. No difference between ipsi- and contralateral sides of the brain in the mouse model of PD was detected. AMPA lesion induced a significant 69% decrease in 18F-IAM6067 uptake in the globus pallidus matching the neuronal loss as measured by NeuN, but only a trend to decrease (-16%) in the caudate putamen despite a significant 91% decrease in neuronal count. Moreover, no difference in the human cortical binding was shown between AD groups and controls. Conclusion: This work shows that 18F-IAM6067 is a specific and selective S1R radiotracer. The absence or small changes in S1R detected here in animal models and human tissue warrants further investigations and suggests that S1R might not be the anticipated ideal biomarker for neuronal loss in neurodegenerative diseases such as AD and PD.
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Affiliation(s)
- François-Xavier Lepelletier
- Faculty of Biology, Medicine and Health, School of Biological Sciences, Division of Neuroscience and Experimental Psychology, University of Manchester, Manchester, United Kingdom
- Wolfson Molecular Imaging Centre, University of Manchester, Manchester, United Kingdom
| | - Matthias Vandesquille
- Faculty of Biology, Medicine and Health, School of Biological Sciences, Division of Neuroscience and Experimental Psychology, University of Manchester, Manchester, United Kingdom
- Wolfson Molecular Imaging Centre, University of Manchester, Manchester, United Kingdom
| | - Marie-Claude Asselin
- Wolfson Molecular Imaging Centre, University of Manchester, Manchester, United Kingdom
- Faculty of Biology, Medicine and Health, School of Health Sciences, Division of Informatics, Imaging and Data Sciences, University of Manchester, Manchester, United Kingdom
| | - Christian Prenant
- Wolfson Molecular Imaging Centre, University of Manchester, Manchester, United Kingdom
| | - Andrew C Robinson
- Salford Royal NHS Foundation Trust, Department of Clinical & Cognitive Neurosciences, Clinical Sciences Building, Salford, United Kingdom
| | - David M A Mann
- Salford Royal NHS Foundation Trust, Department of Clinical & Cognitive Neurosciences, Clinical Sciences Building, Salford, United Kingdom
| | - Michael Green
- Wolfson Molecular Imaging Centre, University of Manchester, Manchester, United Kingdom
- Faculty of Biology, Medicine and Health, School of Health Sciences, Division of Informatics, Imaging and Data Sciences, University of Manchester, Manchester, United Kingdom
| | - Elizabeth Barnett
- Wolfson Molecular Imaging Centre, University of Manchester, Manchester, United Kingdom
- Faculty of Biology, Medicine and Health, School of Health Sciences, Division of Informatics, Imaging and Data Sciences, University of Manchester, Manchester, United Kingdom
| | | | - Marco Mottinelli
- Department of Medicinal Chemistry, College of Pharmacy, University of Florida, Gainesville, FL 32610, USA
| | - Christophe Mesangeau
- Department of BioMolecular Sciences, School of Pharmacy, University of Mississippi, University, MS 38677, USA
| | - Christopher R McCurdy
- Department of Medicinal Chemistry, College of Pharmacy, University of Florida, Gainesville, FL 32610, USA
- UF Translational Drug Development Core, University of Florida, Gainesville, FL 32610, USA
| | - Inga B Fricke
- European Institute for Molecular Imaging (EIMI), Westfälische Wilhelms-Universität (WWU), Münster, Germany
| | - Andreas H. Jacobs
- European Institute for Molecular Imaging (EIMI), Westfälische Wilhelms-Universität (WWU), Münster, Germany
- Department of Geriatrics and Neurology, Johanniter Hospital, Bonn, Germany
| | - Michael Kassiou
- School of Chemistry, The University of Sydney, Sydney, Australia
| | - Hervé Boutin
- Faculty of Biology, Medicine and Health, School of Biological Sciences, Division of Neuroscience and Experimental Psychology, University of Manchester, Manchester, United Kingdom
- Wolfson Molecular Imaging Centre, University of Manchester, Manchester, United Kingdom
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Wilson H, Pagano G, de Natale ER, Mansur A, Caminiti SP, Polychronis S, Middleton LT, Price G, Schmidt KF, Gunn RN, Rabiner EA, Politis M. Mitochondrial Complex 1, Sigma 1, and Synaptic Vesicle 2A in Early Drug-Naive Parkinson's Disease. Mov Disord 2020; 35:1416-1427. [PMID: 32347983 DOI: 10.1002/mds.28064] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 03/27/2020] [Accepted: 03/30/2020] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Dysfunction of mitochondrial energy generation may contribute to neurodegeneration, leading to synaptic loss in Parkinson's disease (PD). The objective of this study was to find cross-sectional and longitudinal changes in PET markers of synaptic vesicle protein 2A, sigma 1 receptor, and mitochondrial complex 1 in drug-naive PD patients. METHODS Twelve early drug-naive PD patients and 16 healthy controls underwent a 3-Tesla MRI and PET imaging to quantify volume of distribution of [11 C]UCB-J, [11 C]SA-4503, and [18 F]BCPP-EF for synaptic vesicle protein 2A, sigma 1 receptor, and mitochondrial complex 1, respectively. Nine PD patients completed approximately 1-year follow-up assessments. RESULTS Reduced [11 C]UCB-J volume of distribution in the caudate, putamen, thalamus, brain stem, and dorsal raphe and across cortical regions was observed in drug-naive PD patients compared with healthy controls. [11 C]UCB-J volume of distribution was reduced in the locus coeruleus and substantia nigra but did not reach statistical significance. No significant differences were found in [11 C]SA-4503 and [18 F]BCPP-EF volume of distribution in PD compared with healthy controls. Lower brain stem [11 C]UCB-J volume of distribution correlated with Movement Disorder Society Unified Parkinson's Disease Rating Scale part III and total scores. No significant longitudinal changes were identified in PD patients at follow-up compared with baseline. CONCLUSIONS Our findings represent the first in vivo evidence of mitochondrial, endoplasmic reticulum, and synaptic dysfunction in drug-naive PD patients. Synaptic dysfunction likely occurs early in disease pathophysiology and has relevance to symptomatology. Mitochondrial complex 1 and sigma 1 receptor pathology warrants further investigations in PD. Studies in larger cohorts with longer follow-up will determine the validity of these PET markers to track disease progression. © 2020 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Heather Wilson
- Neurodegeneration Imaging Group, University of Exeter Medical School, London, UK.,Neurodegeneration Imaging Group, Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK
| | - Gennaro Pagano
- Neurodegeneration Imaging Group, Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK
| | - Edoardo Rosario de Natale
- Neurodegeneration Imaging Group, University of Exeter Medical School, London, UK.,Neurodegeneration Imaging Group, Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK
| | - Ayla Mansur
- Invicro, Centre for Imaging Sciences, Hammersmith Hospital, London, UK.,Division of Brain Sciences, Department of Medicine, Imperial College London, UK
| | - Silvia Paola Caminiti
- Neurodegeneration Imaging Group, Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK
| | - Sotirios Polychronis
- Neurodegeneration Imaging Group, Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK
| | - Lefkos T Middleton
- School of Public Health, Imperial College London, UK.,Public Health Directorate, Imperial College NHS Healthcare Trust, London, UK.,MINDMAPS Consortium, London, UK
| | - Geraint Price
- School of Public Health, Imperial College London, UK.,MINDMAPS Consortium, London, UK
| | | | - Roger N Gunn
- Invicro, Centre for Imaging Sciences, Hammersmith Hospital, London, UK.,Division of Brain Sciences, Department of Medicine, Imperial College London, UK.,MINDMAPS Consortium, London, UK
| | - Eugenii A Rabiner
- Invicro, Centre for Imaging Sciences, Hammersmith Hospital, London, UK.,MINDMAPS Consortium, London, UK.,Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Marios Politis
- Neurodegeneration Imaging Group, University of Exeter Medical School, London, UK.,Neurodegeneration Imaging Group, Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK.,MINDMAPS Consortium, London, UK
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6
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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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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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Penke B, Fülöp L, Szűcs M, Frecska E. The Role of Sigma-1 Receptor, an Intracellular Chaperone in Neurodegenerative Diseases. Curr Neuropharmacol 2018; 16:97-116. [PMID: 28554311 PMCID: PMC5771390 DOI: 10.2174/1570159x15666170529104323] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 04/15/2017] [Accepted: 05/25/2017] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Widespread protein aggregation occurs in the living system under stress or during aging, owing to disturbance of endoplasmic reticulum (ER) proteostasis. Many neurodegenerative diseases may have a common mechanism: the failure of protein homeostasis. Perturbation of ER results in unfolded protein response (UPR). Prolonged chronical UPR may activate apoptotic pathways and cause cell death. METHODS Research articles on Sigma-1 receptor were reviewed. RESULTS ER is associated to mitochondria by the mitochondria-associated ER-membrane, MAM. The sigma-1 receptor (Sig-1R), a well-known ER-chaperone localizes in the MAM. It serves for Ca2+-signaling between the ER and mitochondria, involved in ion channel activities and especially important during neuronal differentiation. Sig-1R acts as central modulator in inter-organelle signaling. Sig-1R helps cell survival by attenuating ER-stress. According to sequence based predictions Sig-1R is a 223 amino acid protein with two transmembrane (2TM) domains. The X-ray structure of the Sig-1R [1] showed a membrane-bound trimeric assembly with one transmembrane (1TM) region. Despite the in vitro determined assembly, the results of in vivo studies are rather consistent with the 2TM structure. The receptor has unique and versatile pharmacological profile. Dimethyl tryptamine (DMT) and neuroactive steroids are endogenous ligands that activate Sig-1R. The receptor has a plethora of interacting client proteins. Sig-1R exists in oligomeric structures (dimer-trimer-octamer-multimer) and this fact may explain interaction with diverse proteins. CONCLUSION Sig-1R agonists have been used in the treatment of different neurodegenerative diseases, e.g. Alzheimer's and Parkinson's diseases (AD and PD) and amyotrophic lateral sclerosis. Utilization of Sig-1R agents early in AD and similar other diseases has remained an overlooked therapeutic opportunity.
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Affiliation(s)
- Botond Penke
- University of Szeged, Department of Medical Chemistry, Faculty of Medicine, Szeged, Hungary
| | - Lívia Fülöp
- University of Szeged, Department of Medical Chemistry, Faculty of Medicine, Szeged, Hungary
| | - Mária Szűcs
- University of Szeged, Department of Medical Chemistry, Faculty of Medicine, Szeged, Hungary
| | - Ede Frecska
- University of Debrecen, Department of Psychiatry, Faculty of Medicine, Debrecen, Hungary
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Maurice T, Goguadze N. Role of σ 1 Receptors in Learning and Memory and Alzheimer's Disease-Type Dementia. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 964:213-233. [PMID: 28315274 DOI: 10.1007/978-3-319-50174-1_15] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The present chapter will review the role of σ1 receptor in learning and memory and neuroprotection , against Alzheimer's type dementia. σ1 Receptor agonists have been tested in a variety of pharmacological and pathological models of learning impairments in rodents these last past 20 years. Their anti-amnesic effects have been explained by the wide-range modulatory role of σ1 receptors on Ca2+ mobilizations, neurotransmitter responses, and particularly glutamate and acetylcholine systems, and neurotrophic factors. Recent observations from genetic and pharmacological studies have shown that σ1 receptor can also be targeted in neurodegenerative diseases, and particularly Alzheimer's disease . Several compounds, acting partly through the σ1 receptor, have showed effective neuroprotection in transgenic mouse models of Alzheimer's disease . We will review the data and discuss the possible mechanisms of action, particularly focusing on oxidative stress and mitochondrial integrity, trophic factors and a novel hypothesis suggesting a functional interaction between the σ1 receptor and α7 nicotinic acetylcholine receptor. Finally, we will discuss the pharmacological peculiarities of non-selective σ1 receptor ligands, now developed as neuroprotectants in Alzheimer's disease , and positive modulators, recently described and that showed efficacy against learning and memory deficits.
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Affiliation(s)
- Tangui Maurice
- INSERM U1198, University of Montpellier, 34095, Montpellier, France.
| | - Nino Goguadze
- INSERM U1198, University of Montpellier, 34095, Montpellier, France
- Institute of Chemical Biology, Ilia State University, Tbilisi, 0162, GA, USA
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10
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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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11
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Abstract
The sigma-1 receptor (Sig-1R), via interaction with various proteins, including voltage-gated and ligand-gated ion channels (VGICs and LGICs), is involved in a plethora of neuronal functions. This capability to regulate a variety of ion channel targets endows the Sig-1R with a powerful capability to fine tune neuronal excitability, and thereby the transmission of information within brain circuits. This versatility may also explain why the Sig-1R is associated to numerous diseases at both peripheral and central levels. To date, how the Sig-1R chooses its targets and how the combinations of target modulations alter overall neuronal excitability is one of the challenges in the field of Sig-1R-dependent regulation of neuronal activity. Here, we will describe and discuss the latest findings on Sig-1R-dependent modulation of VGICs and LGICs, and provide hypotheses that may explain the diverse excitability outcomes that have been reported so far.
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Affiliation(s)
- Saïd Kourrich
- Department of Psychiatry, University of Texas Southwestern Medical Center, 2201 Inwood Road, Dallas, TX, 75390-9070, USA.
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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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Romero L, Merlos M, Vela JM. Antinociception by Sigma-1 Receptor Antagonists: Central and Peripheral Effects. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2016; 75:179-215. [PMID: 26920013 DOI: 10.1016/bs.apha.2015.11.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
There is plenty of evidence supporting the modulatory role of sigma-1 receptors (σ1Rs) in nociception, mainly based on the pain-attenuated phenotype of σ1R knockout mice and on the antinociceptive effect exerted by σ1R antagonists, particularly in nonacute sensitizing conditions involving sustained afferent drive, activity-dependent plasticity/sensitization, and ultimately pain hypersensitivity, as it is the case in chronic pains of different etiology. Antinociceptive effects of σ1R antagonists both when acting alone and in combination with opioids (to enhance opioid analgesia) have been reported at both central and peripheral sites. At the central level, findings at the behavioral (animal pain models), electrophysiological (spinal wind-up recordings), neurochemical (spinal release of neurotransmitters) and molecular (NMDAR function) level supports a role for σ1R antagonists in inhibiting augmented excitability secondary to sustained afferent input. Attenuation of activity-induced plastic changes (central sensitization) following tissue injury/inflammation or nerve damage could thus underlie the central inhibitory effect of σ1R antagonists. Moreover, recent pieces of information confirm the involvement of σ1R in mechanisms regulating pain at the periphery, where σ1Rs are highly expressed, particularly in dorsal root ganglia. Indeed, local peripheral administration of σ1R antagonists reduces inflammatory hyperalgesia. Potentiation of opioid analgesia is also supported, particularly at supraspinal sites and at the periphery, where locally administered σ1R antagonists unmask opioid analgesia. Altogether, whereas σ1R activation is coupled to pain facilitation and inhibition of opioid antinociception, σ1R antagonism inhibits pain hypersensitivity and "releases the brake" enabling opioids to exert enhanced antinociceptive effects, both at the central nervous system and at the periphery.
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Affiliation(s)
- Luz Romero
- Drug Discovery and Preclinical Development, ESTEVE, Parc Científic de Barcelona, Baldiri Reixac 4-8, Barcelona, Spain
| | - Manuel Merlos
- Drug Discovery and Preclinical Development, ESTEVE, Parc Científic de Barcelona, Baldiri Reixac 4-8, Barcelona, Spain
| | - José Miguel Vela
- Drug Discovery and Preclinical Development, ESTEVE, Parc Científic de Barcelona, Baldiri Reixac 4-8, Barcelona, Spain.
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Sahlholm K, Sijbesma JWA, Maas B, Kwizera C, Marcellino D, Ramakrishnan NK, Dierckx RAJO, Elsinga PH, van Waarde A. Pridopidine selectively occupies sigma-1 rather than dopamine D2 receptors at behaviorally active doses. Psychopharmacology (Berl) 2015; 232:3443-53. [PMID: 26159455 PMCID: PMC4537502 DOI: 10.1007/s00213-015-3997-8] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 06/15/2015] [Indexed: 02/07/2023]
Abstract
RATIONALE Dopamine stabilizers have stimulatory actions under low dopamine tone and inhibitory actions under high dopamine tone without eliciting catalepsy. These compounds are dopamine D2 receptor (D2R) antagonists or weak partial agonists and may have pro-mnemonic and neuroprotective effects. The mechanism underlying their stimulatory and neuroprotective actions is unknown but could involve sigma-1R binding. OBJECTIVES The present study examined sigma-1R and D2R occupancy by the dopamine stabilizer pridopidine (ACR16) at behaviorally relevant doses in living rats. METHODS Rats were administered 3 or 15 mg/kg pridopidine, or saline, before injection of the radiotracer (11)C-SA4503 (sigma-1R) or (11)C-raclopride (D2R). Some animals received 60 mg/kg pridopidine and were only scanned with (11)C-raclopride. Cerebral (11)C-SA4503 binding was quantified using metabolite-corrected plasma input data and distribution volume (V T) calculated by Logan graphical analysis. (11)C-raclopride binding was quantified using striatum-to-cerebellum ratios and binding potentials calculated with a simplified reference tissue model. RESULTS Cunningham-Lassen plots indicated sigma-1R occupancies of 57 ± 2 and 85 ± 2% after pretreatment of animals with 3 and 15 mg/kg pridopidine. A significant (44-66%) reduction of (11)C-raclopride binding was only observed at 60 mg/kg pridopidine. CONCLUSIONS At doses shown to elicit neurochemical and behavioral effects, pridopidine occupied a large fraction of sigma-1Rs and a negligible fraction of D2Rs. Significant D2R occupancy was only observed at a dose 20-fold higher than was required for sigma-1R occupancy. The characteristics of dopamine stabilizers may result from the combination of high sigma-1R and low D2R affinity.
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Affiliation(s)
- Kristoffer Sahlholm
- />Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
- />Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Jurgen W. A. Sijbesma
- />Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Bram Maas
- />Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Chantal Kwizera
- />Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Daniel Marcellino
- />Department of Physiology and Institute of Biomedical Technology (ITB), Center for Biomedical Research of the Canary Islands (CIBICAN), University of La Laguna School of Medicine, Tenerife, Spain
| | - Nisha K. Ramakrishnan
- />Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Rudi A. J. O. Dierckx
- />Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Philip H. Elsinga
- />Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Aren van Waarde
- />Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
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15
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Ishiwata A, Mizumura S, Mishina M, Yamazaki M, Katayama Y. The potentially protective effect of donepezil in Alzheimer's disease. Dement Geriatr Cogn Disord 2015; 38:170-7. [PMID: 24732387 DOI: 10.1159/000358510] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 01/08/2014] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS Donepezil is an acetylcholinesterase inhibitor used to treat Alzheimer's disease (AD). In this study, we used a voxel-based specific regional analysis system for AD (VSRAD) to analyze the hippocampal volume and to assess the pharmacologic effects of donepezil as a disease modifier. METHODS A total of 185 AD patients underwent MRI, 120 (43 men and 77 women, 77.8 ± 7.1 years) without and 65 (29 men and 36 women, 78.4 ± 6.0 years) with donepezil treatment. VSRAD was compared in both groups and against a database of 80 normal subjects. The Z-score was used to assess the degree of hippocampal atrophy. RESULTS No significant difference between the groups was found for age, sex, or Z-scores, but a significant difference was found for mean Mini-Mental State Examination (MMSE) scores (p = 0.02, Student's t test). Single regression analysis showed no significant association between Z-scores and MMSE scores in the treated group (p = 0.494), but a significant association in the untreated group (p = 0.001) was observed. This implies that the MMSE score becomes lower when the Z-score is higher in the untreated group, whereas there is no significant trend in the treated group. CONCLUSION Donepezil affects the relationship between hippocampal volume and cognitive function and may therefore have a pharmacologic effect as a disease modifier.
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Affiliation(s)
- Akiko Ishiwata
- Department of Neurological Science, Graduate School of Medicine, Nippon Medical School, Tokyo, Japan
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Banister SD, Manoli M, Kassiou M. The development of radiotracers for imaging sigma (σ) receptors in the central nervous system (CNS) using positron emission tomography (PET). J Labelled Comp Radiopharm 2014; 56:215-24. [PMID: 24285328 DOI: 10.1002/jlcr.3010] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Revised: 11/19/2012] [Accepted: 11/20/2012] [Indexed: 11/10/2022]
Abstract
Sigma (σ) receptors are unique mammalian proteins, distributed in the central nervous system and elsewhere, which are increasingly implicated in the pathophysiology of virtually all major central nervous system disorders. The heterogeneous but wide distribution of σ1 in the brain has prompted the development of selective radiotracers for imaging these sites using positron emission tomography (PET). To date, some 50 carbon-11-labelled and fluorine-18-labelled candidate PET radioligands targeting σ receptors have been reported. The historical development of selective σ1 receptor ligands as potential PET imaging agents, as well as the radiochemistry and application of the most recently developed examples, is described herein.
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Affiliation(s)
- Samuel D Banister
- Brain and Mind Research Institute, The University of Sydney, NSW, 2050, Australia; School of Chemistry, The University of Sydney, NSW, 2006, Australia
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Kourrich S, Su TP, Fujimoto M, Bonci A. The sigma-1 receptor: roles in neuronal plasticity and disease. Trends Neurosci 2012; 35:762-71. [PMID: 23102998 PMCID: PMC3587126 DOI: 10.1016/j.tins.2012.09.007] [Citation(s) in RCA: 181] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Revised: 08/14/2012] [Accepted: 09/20/2012] [Indexed: 12/31/2022]
Abstract
Sigma-1 receptors (Sig-1Rs) have been implicated in many neurological and psychiatric conditions. Sig-1Rs are intracellular chaperones that reside specifically at the endoplasmic reticulum (ER)-mitochondrion interface, referred to as the mitochondrion-associated ER membrane (MAM). Here, Sig-1Rs regulate ER-mitochondrion Ca(2+) signaling. In this review, we discuss the current understanding of Sig-1R functions. Based on this, we suggest that the key cellular mechanisms linking Sig-1Rs to neurological disorders involve the translocation of Sig-1Rs from the MAM to other parts of the cell, whereby Sig-1Rs bind and modulate the activities of various ion channels, receptors, or kinases. Thus, Sig-1Rs and their associated ligands may represent new avenues for treating aspects of neurological and psychiatric diseases.
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Affiliation(s)
- Saïd Kourrich
- Synaptic Plasticity Section, Intramural Research Program, National Institute on Drug Abuse (NIDA), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Baltimore, MD, USA
| | - Tsung-Ping Su
- Cellular Pathobiology Section, Intramural Research Program, NIDA, NIH, DHHS, Baltimore, MD USA
| | - Michiko Fujimoto
- Cellular Pathobiology Section, Intramural Research Program, NIDA, NIH, DHHS, Baltimore, MD USA
| | - Antonello Bonci
- Synaptic Plasticity Section, Intramural Research Program, National Institute on Drug Abuse (NIDA), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Baltimore, MD, USA
- Department of Neurology, University of California, San Francisco, CA, USA
- Solomon H. Snyder Neuroscience Institute, Johns Hopkins University School of Medicine, Baltimore, CA, USA
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van Waarde A, Ramakrishnan NK, Rybczynska AA, Elsinga PH, Ishiwata K, Nijholt IM, Luiten PGM, Dierckx RA. The cholinergic system, sigma-1 receptors and cognition. Behav Brain Res 2011; 221:543-54. [PMID: 20060423 DOI: 10.1016/j.bbr.2009.12.043] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2009] [Accepted: 12/26/2009] [Indexed: 12/31/2022]
Abstract
This article provides an overview of present knowledge regarding the relationship between the cholinergic system and sigma-1 receptors, and discusses potential applications of sigma-1 receptor agonists in the treatment of memory deficits and cognitive disorders. Sigma-1 receptors, initially considered as a subtype of the opioid family, are unique ligand-regulated molecular chaperones in the endoplasmatic reticulum playing a modulatory role in intracellular calcium signaling and in the activity of several neurotransmitter systems, particularly the cholinergic and glutamatergic pathways. Several central nervous system (CNS) drugs show high to moderate affinities for sigma-1 receptors, including acetylcholinesterase inhibitors (donepezil), antipsychotics (haloperidol, rimcazole), selective serotonin reuptake inhibitors (fluvoxamine, sertraline) and monoamine oxidase inhibitors (clorgyline). These compounds can influence cognitive functions both via their primary targets and by activating sigma-1 receptors in the CNS. Sigma-1 agonists show powerful anti-amnesic and neuroprotective effects in a large variety of animal models of cognitive dysfunction involving, among others (i) pharmacologic target blockade (with muscarinic or NMDA receptor antagonists or p-chloroamphetamine); (ii) selective lesioning of cholinergic neurons; (iii) CNS administration of β-amyloid peptides; (iv) aging-induced memory loss, both in normal and senescent-accelerated rodents; (v) neurodegeneration induced by toxic compounds (CO, trimethyltin, cocaine), and (vi) prenatal restraint stress.
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Affiliation(s)
- 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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Fishback JA, Mesangeau C, Poupaert JH, McCurdy CR, Matsumoto RR. Synthesis and characterization of [³H]-SN56, a novel radioligand for the σ₁ receptor. Eur J Pharmacol 2011; 653:1-7. [PMID: 21130085 PMCID: PMC3726058 DOI: 10.1016/j.ejphar.2010.10.099] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2010] [Revised: 09/30/2010] [Accepted: 10/06/2010] [Indexed: 11/25/2022]
Abstract
The study of the binding characteristics of σ ligands in vivo and in vitro requires radiolabeled probes with high affinity and selectivity. The radioligand presently used for in vitro studies of the σ₁ receptor, [³H](+)-pentazocine, has significant limitations; it is difficult to synthesize, has limited chemical stability, and can be problematic to obtain. Evaluation of a series of novel 2(3H)-benzothiazolone compounds revealed SN56 to have sub-nanomolar and preferential affinity for the σ₁ subtype, relative to σ₂ and non-sigma, binding sites. The goal of this study was to characterize the binding of [³H]-SN56 to σ₁ receptors isolated from rat brain. Standard in vitro binding techniques were utilized to 1) determine the specificity and affinity of binding to σ₁ receptors, 2) confirm that[³H]-SN56 labels sites previously identified as σ₁ by comparing binding to sites labeled by [³H](+)-pentazocine, and 3) characterize the kinetics of binding. The results indicate that [³H]-SN56 exhibits 1) specific, saturable, and reversible binding to the σ₁ receptor, with B(max)=340±10 fmol/mg and K(d)=0.069±0.0074 nM, 2) competitive displacement by classical sigma compounds, yielding σ₁ K(i) values consistent with those reported in the literature, and 3) binding kinetics compatible with a 90 min incubation, and filtration for separation of free and bound radioligand. The results of these studies suggest that [(3)H]-SN56 may serve as a viable alternative to [³H](+)-pentazocine in radioligand binding assays.
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Affiliation(s)
- James A. Fishback
- Department of Basic Pharmaceutical Sciences, West Virginia University, Morgantown, WV 26506, USA
- Department of Pharmacology, University of Mississippi, University, MS 38677, USA
| | - Christophe Mesangeau
- Department of Medicinal Chemistry, University of Mississippi, University, MS 38677, USA
| | - Jacques H. Poupaert
- Universite Catholique de Louvain, Avenue Emmanuel Mounier 74, B-1200, Brussels, Belgium
| | | | - Rae R. Matsumoto
- Department of Basic Pharmaceutical Sciences, West Virginia University, Morgantown, WV 26506, USA
- Department of Pharmacology, University of Mississippi, University, MS 38677, USA
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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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Maestrup EG, Fischer S, Wiese C, Schepmann D, Hiller A, Deuther-Conrad W, Steinbach J, Wünsch B, Brust P. Evaluation of spirocyclic 3-(3-fluoropropyl)-2-benzofurans as sigma1 receptor ligands for neuroimaging with positron emission tomography. J Med Chem 2009; 52:6062-72. [PMID: 19791807 DOI: 10.1021/jm900909e] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A series of various N-substituted 3-(3-fluoropropyl)-3H-spiro[[2]benzofuran-1,4'-piperidines] (7) has been synthesized. In receptor binding studies, the N-benzyl derivative 7a (WMS-1813) revealed extraordinarily high sigma(1) receptor affinity (K(i) = 1.4 nM) and excellent sigma(1)/sigma(2) selectivity (>600 fold). In vitro biotransformation of 7a with rat liver microsomes led to three main metabolites. N-Debenzylation was inhibited by introduction of an N-phenylethyl residue (7 g). The PET tracer [(18)F]7a was synthesized by nucleophilic substitution of the tosylate 13 with K[(18)F]F-K222-carbonate complex. The decay corrected radiochemical yield of [(18)F]7a was 35-48% with a radiochemical purity of >99.5% and a specific activity of 150-238 GBq/micromol. The radiotracer properties were evaluated in female CD-1 mice by organ distribution and ex vivo brain autoradiography. The radiotracer uptake in the brain was fast and sufficient, with values of approximately 4% injected dose per gram. Target specificity of [(18)F]7a was validated in blocking studies by preapplication of haloperidol, and significant reduction in the uptake of radioactivity was observed in the brain and peripheral organs expressing sigma(1) receptors.
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Affiliation(s)
- Eva Grosse Maestrup
- Institut für Pharmazeutische und Medizinische Chemie der Westfälischen Wilhelms-Universität Münster, Münster, Germany
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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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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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Lever JR, Gustafson JL, Xu R, Allmon RL, Lever SZ. Sigma1 and sigma2 receptor binding affinity and selectivity of SA4503 and fluoroethyl SA4503. Synapse 2006; 59:350-8. [PMID: 16463398 DOI: 10.1002/syn.20253] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
SA4503, a potent sigma(1) receptor agonist, is reported as having 103-fold higher affinity for sigma(1) (IC(50) = 17.4 nM) than sigma(2) (IC(50) = 1,784 nM) sites in guinea pig brain membranes. Modest structural changes appear to have major effects on sigma(1)/sigma(2) selectivity. The fluoroethyl analog, FE-SA4503, is described as having high primary affinity for sigma(2) sites (IC(50) = 2.11 nM) and a weaker interaction with sigma(1) sites (IC(50) = 6.48 nM). SA4503 and FE-SA4503 have been radiolabeled for PET studies, and both bind selectively to sigma(1) receptors in animal and human brain in vivo. We prepared SA4503 and FE-SA4503 as reference compounds for radioligand development efforts. In our hands, SA4503 is 14-fold selective for sigma(1) (K(i) = 4.6 nM) over sigma(2) (K(i) = 63.1 nM) sites in guinea pig brain homogenates. Further, FE-SA4503 exhibits the same 14-fold selectivity for sigma(1) (K(i) = 8.0 nM) over sigma(2) (K(i) = 113.2 nM) receptors. The main differences from previously reported values stem from sigma(2) affinity determinations. This protocol, displacement of [(3)H]DTG binding to sigma(2) sites using (+)-pentazocine (200 nM) to mask sigma(1) sites, was validated by the proper rank order of sigma(2) inhibitory potencies shown by a panel of additional ligands: ifenprodil > haloperidol > DTG >> (+)-pentazocine. Robust Pearson correlation (r = 1.0, P = 0.002; slope = 0.97) was observed for our pK(i) values against those from a prior study by others. The findings have bearing on structure-activity relationships for this active series, and on conclusions that might be drawn from experiments relying upon defined sigma(1)/sigma(2) binding selectivity.
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Affiliation(s)
- John R Lever
- Department of Radiology, University of Missouri-Columbia, 65211, USA.
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Mishina M, Ishiwata K, Ishii K, Kitamura S, Kimura Y, Kawamura K, Oda K, Sasaki T, Sakayori O, Hamamoto M, Kobayashi S, Katayama Y. Function of sigma1 receptors in Parkinson's disease. Acta Neurol Scand 2005; 112:103-7. [PMID: 16008536 DOI: 10.1111/j.1600-0404.2005.00432.x] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVE The objective of this study was to investigate the mapping of sigma1 receptors in Parkinson's disease (PD) using [11C]SA4503 and positron emission tomography (PET), and to assess whether sigma1 receptors are involved in the damaged dopaminergic system in PD patients. MATERIALS AND METHODS We studied seven normal volunteers and six PD patients. The low density of dopamine transporters and the normal or high density of dopamine receptors were confirmed in the putamen of all patients using [11C]CFT and [11C]RAC PET. A dynamic series of PET data acquisition was performed with arterial blood sampling. We computed the binding potential (BP) of [11C]SA4503. RESULTS In PD patients, the BP was significantly lower on the more affected than the less affected side of the anterior putamen, although there was no significant difference with respect to the BP between patients and controls. CONCLUSIONS Release of dopamine is reduced asymmetrically in the putamen of early PD. [11C]SA4503 PET is an indicator of presynaptic dopaminergic damage in PD.
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Affiliation(s)
- M Mishina
- The Department of Neurology, Neurological Institute, Nippon Medical School Chiba-Hokusoh Hospital, Inba-Gun, Chiba, Japan.
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Staelens L, Oltenfreiter R, Blanckaert P, Kersemans V, Vandenbulcke K, Van De Wiele C, Slegers G. In vivo evaluation of [123I]-3-(4-iodobenzyl)-1,2,3,4-tetrahydro-8-hydroxychromeno[3,4-c]pyridin-5-one: a presumed dopamine D4 receptor ligand for SPECT studies. Nucl Med Biol 2005; 32:293-9. [PMID: 15820765 DOI: 10.1016/j.nucmedbio.2004.12.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2004] [Revised: 12/19/2004] [Accepted: 12/23/2004] [Indexed: 10/25/2022]
Abstract
[(123)I]-3-(4-iodobenzyl)-1,2,3,4-tetrahydro-8-hydroxychromeno[3,4-c]pyridin-5-one ([(123)I]-ITCP), a presumed radioligand for visualization of the dopamine D4 receptor by single photon emission computed tomography, was evaluated in vivo in mice and rabbits. This new radioiodinated tracer exhibited high brain uptake (3.64% injected dose per gram of tissue at 10 min p.i.) in mice. No significant amounts (less than 5%) of labeled metabolites were present in the brain, as demonstrated by a metabolite study. Regional brain distribution in rabbits showed atypical CNS uptake with consistently low values in the cortex and high values in other brain parts including cerebellum. Saturable binding was confirmed by a competition experiment with unlabeled product. Selectivity was assessed by competition experiments with a known dopamine D4 ligand and later with a sigma receptor ligand. Both experiments showed no observable competition. In conclusion, our findings indicate that [(123)I]-ITCP is neither a dopamine D4 receptor ligand nor a sigma receptor ligand. The exact nature of [(123)I]-ITCP binding in the brain remains to be elucidated.
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Affiliation(s)
- Ludovicus Staelens
- Department of Radiopharmacy, Faculty of Pharmaceutical Sciences, Gent University, B-9000 Gent, Belgium.
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Elsinga PH, Tsukada H, Harada N, Kakiuchi T, Kawamura K, Vaalburg W, Kimura Y, Kobayashi T, Ishiwata K. Evaluation of [18F]fluorinated sigma receptor ligands in the conscious monkey brain. Synapse 2004; 52:29-37. [PMID: 14755630 DOI: 10.1002/syn.20001] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
PET-imaging of the sigma receptors is very helpful to understand processes, e.g., several central nervous system (CNS)-diseases in which the sigma receptors are involved. The [(18)F]fluoroethylated analogs of SA4503 and SA5845 ([(18)F]FE-SA4503 and [(18)F]FE-SA5845) were evaluated in conscious monkeys to estimate its suitability for human application for PET. Conscious monkeys (Macaca Mulatta) were either scanned with [(18)F]FE-SA4503 or [(18)F]FE-SA5845 (n = 3 for both groups, 220-802 MBq). After a dynamic study of 120 min, radioactivity was displaced by intravenous (i.v.) injection of haloperidol (1 mg/kg). One month later the same set of three monkeys were scanned with [(18)F]FE-SA4503 for 120 min and "cold" SA4503 (1 mg/kg) was infused to displace the radioactivity, and the other three monkeys were pretreated with haloperidol (1 mg/kg) before the 120-min PET-scan with [(18)F]FE-SA5845. Cortical areas (cingulate, frontal, occipital, parietal, temporal), striatum, and thalamus showed high radioactivity uptake. Infusion of haloperidol displaced the radioactivity levels of the two radioligands. The same effect was found for [(18)F]FE-SA4503 after SA4503 displacement. Pretreatment with haloperidol blocked the [(18)F]FE-SA5845 binding to give PET-images with low and uniform uptake in the brain. The findings demonstrated the reversible binding of the two radioligands. Metabolite analysis showed that 14% and 23% parent compound of [(18)F]FE-SA5845 and [(18)F]FE-SA4503, respectively, at 120 min postinjection was present in plasma. Kinetic analysis showed that the binding potential of [(18)F]FE-SA5845 was higher in all brain regions than that of [(18)F]FE-SA4503 (4.75-8.79 vs. 1.65-4.04). The highest binding potential was found in the hippocampus, followed by the cortical regions, thalamus, cerebellar hemisphere, striatum and vermis. Both [(18)F]FE-SA compounds bound specifically to cerebral sigma receptors of the monkey and have potential for mapping sigma receptors in the human brain.
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Affiliation(s)
- P H Elsinga
- PET-Center, Groningen University Hospital, Groningen, The Netherlands.
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