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Ceyzériat K, Nicolaides A, Amossé Q, Fossey C, Cailly T, Fabis F, Garibotto V, Escartin C, Tournier BB, Millet P. Reactive astrocytes mediate TSPO overexpression in response to sustained CNTF exposure in the rat striatum. Mol Brain 2023; 16:57. [PMID: 37408083 DOI: 10.1186/s13041-023-01041-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 06/01/2023] [Indexed: 07/07/2023] Open
Abstract
The 18 kDa translocator protein (TSPO) is a classical marker of neuroinflammation targeted for in vivo molecular imaging. Microglial cells were originally thought to be the only source of TSPO overexpression but astrocytes, neurons and endothelial cells can also up-regulate TSPO depending on the pathological context. This study aims to determine the cellular origin of TSPO overexpression in a simplified model of neuroinflammation and to identify the molecular pathways involved. This is essential to better interpret TSPO molecular imaging in preclinical and clinical settings. We used lentiviral vectors (LV) to overexpress the ciliary neurotrophic factor (CNTF) in the right striatum of 2-month-old Sprague Dawley rats. A LV encoding for β-Galactosidase (LV-LacZ) was used as control. One month later, TSPO expression was measured by single-photon emission computed tomography (SPECT) imaging using [125I]CLINDE. The fluorescence-activated cell sorting to radioligand-treated tissue (FACS-RTT) method was used to quantify TSPO levels in acutely sorted astrocytes, microglia, neurons and endothelial cells. A second cohort was injected with LV-CNTF and a LV encoding suppressor of cytokine signaling 3 (SOCS3), to inhibit the JAK-STAT3 pathway specifically in astrocytes. GFAP and TSPO expressions were quantified by immunofluorescence. We measured a significant increase in TSPO signal in response to CNTF by SPECT imaging. Using FACS-RTT, we observed TSPO overexpression in reactive astrocytes (+ 153 ± 62%) but also in microglia (+ 2088 ± 500%) and neurons (+ 369 ± 117%), accompanied by an increase in TSPO binding sites per cell in those three cell populations. Endothelial cells did not contribute to TSPO signal increase. Importantly, LV-SOCS3 reduced CNTF-induced astrocyte reactivity and decreased global TSPO immunoreactivity (-71% ± 30%), suggesting that TSPO overexpression is primarily mediated by reactive astrocytes. Overall, this study reveals that CNTF induces TSPO in multiple cell types in the rat striatum, through the JAK2-STAT3 pathway in astrocytes, identifying this cell type as the primary mediator of CNTF effects neuroinflammatory processes. Our results highlight the difficulty to interpret TSPO imaging in term of cellular origin without addition cellular analysis by FACS-RTT or quantitative immunostainings. Consequently, TSPO should only be used as a global marker of neuroinflammation.
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Affiliation(s)
- Kelly Ceyzériat
- Division of Adult Psychiatry, Department of Psychiatry, University Hospitals of Geneva, Geneva, Switzerland.
- Department of Psychiatry, University of Geneva, Avenue de la Roseraie, 64, Geneva, 1205, Switzerland.
- CIBM Center for BioMedical Imaging, Faculty of Medicine, University of Geneva, Geneva, Switzerland.
| | - Alekos Nicolaides
- Division of Adult Psychiatry, Department of Psychiatry, University Hospitals of Geneva, Geneva, Switzerland
- Department of Psychiatry, University of Geneva, Avenue de la Roseraie, 64, Geneva, 1205, Switzerland
| | - Quentin Amossé
- Division of Adult Psychiatry, Department of Psychiatry, University Hospitals of Geneva, Geneva, Switzerland
- Department of Psychiatry, University of Geneva, Avenue de la Roseraie, 64, Geneva, 1205, Switzerland
| | - Christine Fossey
- Normandie Univ, UNICAEN, Centre d'Études et de Recherche sur le Médicament de Normandie (CERMN), Caen, France
| | - Thomas Cailly
- Normandie Univ, UNICAEN, Centre d'Études et de Recherche sur le Médicament de Normandie (CERMN), Caen, France
- Department of Nuclear Medicine, CHU Cote de Nacre, Caen, France
- Normandie Univ, UNICAEN, IMOGERE, Caen, France
- Institut Blood and Brain @Caen-Normandie (BB@C) Boulevard Henri Becquerel, Caen, 14074, France
| | - Frédéric Fabis
- Normandie Univ, UNICAEN, Centre d'Études et de Recherche sur le Médicament de Normandie (CERMN), Caen, France
| | - Valentina Garibotto
- CIBM Center for BioMedical Imaging, Faculty of Medicine, University of Geneva, Geneva, Switzerland
- Division of nuclear medicine and molecular imaging, Diagnostic Department, Geneva University Hospitals and University of Geneva, Geneva, Switzerland
| | - Carole Escartin
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, Fontenay-aux-Roses, Gif-sur-Yvette, France
| | - Benjamin B Tournier
- Division of Adult Psychiatry, Department of Psychiatry, University Hospitals of Geneva, Geneva, Switzerland
- Department of Psychiatry, University of Geneva, Avenue de la Roseraie, 64, Geneva, 1205, Switzerland
| | - Philippe Millet
- Division of Adult Psychiatry, Department of Psychiatry, University Hospitals of Geneva, Geneva, Switzerland
- Department of Psychiatry, University of Geneva, Avenue de la Roseraie, 64, Geneva, 1205, Switzerland
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In Vivo TSPO Signal and Neuroinflammation in Alzheimer's Disease. Cells 2020; 9:cells9091941. [PMID: 32839410 PMCID: PMC7565089 DOI: 10.3390/cells9091941] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 08/17/2020] [Accepted: 08/18/2020] [Indexed: 12/15/2022] Open
Abstract
In the last decade, positron emission tomography (PET) and single-photon emission computed tomography (SPECT) in in vivo imaging has attempted to demonstrate the presence of neuroinflammatory reactions by measuring the 18 kDa translocator protein (TSPO) expression in many diseases of the central nervous system. We focus on two pathological conditions for which neuropathological studies have shown the presence of neuroinflammation, which translates in opposite in vivo expression of TSPO. Alzheimer's disease has been the most widely assessed with more than forty preclinical and clinical studies, showing overall that TSPO is upregulated in this condition, despite differences in the topography of this increase, its time-course and the associated cell types. In the case of schizophrenia, a reduction of TSPO has instead been observed, though the evidence remains scarce and contradictory. This review focuses on the key characteristics of TSPO as a biomarker of neuroinflammation in vivo, namely, on the cellular origin of the variations in its expression, on its possible biological/pathological role and on its variations across disease phases.
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Tsartsalis S, Tournier BB, Millet P. In vivo absolute quantification of striatal and extrastriatal D 2/3 receptors with [ 123I]epidepride SPECT. EJNMMI Res 2020; 10:66. [PMID: 32548681 PMCID: PMC7297889 DOI: 10.1186/s13550-020-00650-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Accepted: 05/27/2020] [Indexed: 01/08/2023] Open
Abstract
Background [123I]epidepride is a high-affinity radiotracer used in single-photon emission computed tomography (SPECT) imaging of the D2/3 receptors. It binds with high affinity to striatal and extrastriatal receptors. Nevertheless, its slow kinetics in the striatum impedes quantification in this region. Thus, an approach that would allow a simultaneous quantification of both striatal and extrastriatal D2/3 receptors would be of interest for preclinical and clinical SPECT neuroimaging. We describe a partial saturation protocol that allows us to produce an in vivo Scatchard plot and thus estimate Bavail and appKd separately in both striatal and extrastriatal regions, through a single dynamic SPECT session. To validate this approach, a multi-injection protocol is used for the full kinetic modeling of [123I]epidepride using a two-tissue compartment, 5-parameter model (2T-5k). Methods Eighteen male rats were used. Binding parameters were estimated using the multi-injection protocol. Various simulations were performed to estimate the optimal conditions for the partial saturation protocol, which was applied at the region and voxel level. The results of the partial saturation study were compared to those obtained with the 2T-5k model. To illustrate the interest of the partial saturation approach, we performed a preliminary study of the effect of a chronic, subcutaneous administration of haloperidol (1 mg/kg/day), a D2 receptor antagonist, on the Bavail of [123I]epidepride in the rat striatum. Results A series of simulations demonstrated that a mass of 3 ug/kg of unlabeled epidepride allows the formation of an in vivo Scatchard plot. The partial saturation study led to robust estimations of Bavail in all brain regions that highly correlated (r = 0.99) with the corresponding values from the multi-injection study. A chronic haloperidol treatment resulted in a 17.9% increase in the Bavail values in the left Caudate Putamen nucleus (CP) (p = 0.07) and a 13.8% increase in the right CP (p = 0.12). Conclusion A partial saturation method allowed the robust quantification of D2/3 receptors in striatal and extrastriatal D2/3 receptors with a single-scan approach. This approach may be applied in the mapping of the D2/3 receptor in translational biological studies and potentially, in clinical SPECT imaging.
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Affiliation(s)
- Stergios Tsartsalis
- Division of Adult Psychiatry, Department of Psychiatry, University Hospitals of Geneva, Chemin du Petit-Bel-Air 2, CH1226, Thônex, Switzerland.,Division of Psychiatric Specialties, Department of Psychiatry, University Hospitals of Geneva, Geneva, Switzerland
| | - Benjamin B Tournier
- Division of Adult Psychiatry, Department of Psychiatry, University Hospitals of Geneva, Chemin du Petit-Bel-Air 2, CH1226, Thônex, Switzerland
| | - Philippe Millet
- Division of Adult Psychiatry, Department of Psychiatry, University Hospitals of Geneva, Chemin du Petit-Bel-Air 2, CH1226, Thônex, Switzerland. .,Department of Psychiatry, University of Geneva, Geneva, Switzerland.
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Tournier BB, Tsartsalis S, Ceyzériat K, Medina Z, Fraser BH, Grégoire MC, Kövari E, Millet P. Fluorescence-activated cell sorting to reveal the cell origin of radioligand binding. J Cereb Blood Flow Metab 2020; 40:1242-1255. [PMID: 31242048 PMCID: PMC7238369 DOI: 10.1177/0271678x19860408] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Many studies have explored the role of TSPO (18 kDa translocator protein) as a marker of neuroinflammation using single-photon emission computed tomography (SPECT) or positron emission tomography (PET). In vivo imaging does not allow to determine the cells in which TSPO is altered. We propose a methodology based on fluorescence-activated cell sorting to sort different cell types of radioligand-treated tissues. We compared left/right hippocampus of rats in response to a unilateral injection of lipopolysaccharide (LPS), ciliary neurotrophic factor (CNTF) or saline. We finally applied this methodology in human samples (Alzheimer's disease patients and controls). Our data show that the pattern of TSPO overexpression differs across animal models of acute neuroinflammation. LPS induces a microglial expansion and an increase in microglial TSPO binding. CNTF is associated with an increase in TSPO binding in microglia and astrocytes in association with an increase in the number of microglial binding sites per cell. In humans, we show that the increase in CLINDE binding in Alzheimer's disease concerns microglia and astrocytes in the presence of a microglial expansion. Thus, the cellular basis of TSPO overexpression is condition dependent, and alterations in TSPO binding found in PET/SPECT imaging studies cannot be attributed to particular cell types indiscriminately.
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Affiliation(s)
- Benjamin B Tournier
- Division of Adult Psychiatry, Department of Psychiatry, University Hospitals of Geneva, Geneva, Switzerland
| | - Stergios Tsartsalis
- Division of Adult Psychiatry, Department of Psychiatry, University Hospitals of Geneva, Geneva, Switzerland
| | - Kelly Ceyzériat
- Division of Adult Psychiatry, Department of Psychiatry, University Hospitals of Geneva, Geneva, Switzerland.,Division of Nuclear medicine, University Hospitals of Geneva, Geneva, Switzerland
| | - Zadith Medina
- Division of Adult Psychiatry, Department of Psychiatry, University Hospitals of Geneva, Geneva, Switzerland
| | - Ben H Fraser
- ANSTO LifeSciences, Australian Nuclear Science and Technology Organisation, Sydney, NSW, Australia
| | - Marie-Claude Grégoire
- ANSTO LifeSciences, Australian Nuclear Science and Technology Organisation, Sydney, NSW, Australia
| | - Enikö Kövari
- Division of Geriatric Psychiatry, Department of Psychiatry, University Hospitals of Geneva, Geneva, Switzerland.,Department of Psychiatry, University of Geneva, Geneva, Switzerland
| | - Philippe Millet
- Division of Adult Psychiatry, Department of Psychiatry, University Hospitals of Geneva, Geneva, Switzerland.,Department of Psychiatry, University of Geneva, Geneva, Switzerland
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Longitudinal mouse-PET imaging: a reliable method for estimating binding parameters without a reference region or blood sampling. Eur J Nucl Med Mol Imaging 2020; 47:2589-2601. [PMID: 32211931 PMCID: PMC7515949 DOI: 10.1007/s00259-020-04755-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Accepted: 03/03/2020] [Indexed: 01/06/2023]
Abstract
Abstract Longitudinal mouse PET imaging is becoming increasingly popular due to the large number of transgenic and disease models available but faces challenges. These challenges are related to the small size of the mouse brain and the limited spatial resolution of microPET scanners, along with the small blood volume making arterial blood sampling challenging and impossible for longitudinal studies. The ability to extract an input function directly from the image would be useful for quantification in longitudinal small animal studies where there is no true reference region available such as TSPO imaging. Methods Using dynamic, whole-body 18F-DPA-714 PET scans (60 min) in a mouse model of hippocampal sclerosis, we applied a factor analysis (FA) approach to extract an image-derived input function (IDIF). This mouse-specific IDIF was then used for 4D-resolution recovery and denoising (4D-RRD) that outputs a dynamic image with better spatial resolution and noise properties, and a map of the total volume of distribution (VT) was obtained using a basis function approach in a total of 9 mice with 4 longitudinal PET scans each. We also calculated percent injected dose (%ID) with and without 4D-RRD. The VT and %ID parameters were compared to quantified ex vivo autoradiography using regional correlations of the specific binding from autoradiography against VT and %ID parameters. Results The peaks of the IDIFs were strongly correlated with the injected dose (Pearson R = 0.79). The regional correlations between the %ID estimates and autoradiography were R = 0.53 without 4D-RRD and 0.72 with 4D-RRD over all mice and scans. The regional correlations between the VT estimates and autoradiography were R = 0.66 without 4D-RRD and 0.79 with application of 4D-RRD over all mice and scans. Conclusion We present a FA approach for IDIF extraction which is robust, reproducible and can be used in quantification methods for resolution recovery, denoising and parameter estimation. We demonstrated that the proposed quantification method yields parameter estimates closer to ex vivo measurements than semi-quantitative methods such as %ID and is immune to tracer binding in tissue unlike reference tissue methods. This approach allows for accurate quantification in longitudinal PET studies in mice while avoiding repeated blood sampling. Electronic supplementary material The online version of this article (10.1007/s00259-020-04755-5) contains supplementary material, which is available to authorized users.
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Tournier BB, Tsartsalis S, Rigaud D, Fossey C, Cailly T, Fabis F, Pham T, Grégoire MC, Kövari E, Moulin-Sallanon M, Savioz A, Millet P. TSPO and amyloid deposits in sub-regions of the hippocampus in the 3xTgAD mouse model of Alzheimer’s disease. Neurobiol Dis 2019; 121:95-105. [DOI: 10.1016/j.nbd.2018.09.022] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 09/03/2018] [Accepted: 09/23/2018] [Indexed: 11/16/2022] Open
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Tsartsalis S, Tournier BB, Graf CE, Ginovart N, Ibáñez V, Millet P. Dynamic image denoising for voxel-wise quantification with Statistical Parametric Mapping in molecular neuroimaging. PLoS One 2018; 13:e0203589. [PMID: 30183783 PMCID: PMC6124809 DOI: 10.1371/journal.pone.0203589] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2017] [Accepted: 08/23/2018] [Indexed: 11/18/2022] Open
Abstract
Purpose PET and SPECT voxel kinetics are highly noised. To our knowledge, no study has determined the effect of denoising on the ability to detect differences in binding at the voxel level using Statistical Parametric Mapping (SPM). Methods In the present study, groups of subject-images with a 10%- and 20%- difference in binding of [123I]iomazenil (IMZ) were simulated. They were denoised with Factor Analysis (FA). Parametric images of binding potential (BPND) were produced with the simplified reference tissue model (SRTM) and the Logan non-invasive graphical analysis (LNIGA) and analyzed using SPM to detect group differences. FA was also applied to [123I]IMZ and [11C]flumazenil (FMZ) clinical images (n = 4) and the variance of BPND was evaluated. Results Estimations from FA-denoised simulated images provided a more favorable bias-precision profile in SRTM and LNIGA quantification. Simulated differences were detected in a higher number of voxels when denoised simulated images were used for voxel-wise estimations, compared to quantification on raw simulated images. Variability of voxel-wise binding estimations on denoised clinical SPECT and PET images was also significantly diminished. Conclusion In conclusion, noise removal from dynamic brain SPECT and PET images may optimize voxel-wise BPND estimations and detection of biological differences using SPM.
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Affiliation(s)
- Stergios Tsartsalis
- Division of Adult Psychiatry, Geneva University Hospitals, Geneva, Switzerland
- Department of Psychiatry, Faculty of Medicine, University of Geneva, Geneva, Switzerland
- Addictology Division, Geneva University Hospitals, Geneva, Switzerland
- * E-mail:
| | | | - Christophe E. Graf
- Division of Medical Rehabilitation, Geneva University Hospitals, Geneva, Switzerland
| | - Nathalie Ginovart
- Division of Adult Psychiatry, Geneva University Hospitals, Geneva, Switzerland
- Department of Psychiatry, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Vicente Ibáñez
- Clinical Neurophysiology Unit, Division of Psychiatric Specialties, Geneva University Hospitals, Geneva, Switzerland
| | - Philippe Millet
- Division of Adult Psychiatry, Geneva University Hospitals, Geneva, Switzerland
- Department of Psychiatry, Faculty of Medicine, University of Geneva, Geneva, Switzerland
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Tsartsalis S, Tournier BB, Habiby S, Ben Hamadi M, Barca C, Ginovart N, Millet P. Dual-radiotracer translational SPECT neuroimaging. Comparison of three methods for the simultaneous brain imaging of D2/3 and 5-HT2A receptors. Neuroimage 2018; 176:528-540. [DOI: 10.1016/j.neuroimage.2018.04.063] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 03/11/2018] [Accepted: 04/27/2018] [Indexed: 12/27/2022] Open
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Wimberley C, Lavisse S, Brulon V, Peyronneau MA, Leroy C, Bodini B, Remy P, Stankoff B, Buvat I, Bottlaender M. Impact of Endothelial 18-kDa Translocator Protein on the Quantification of 18F-DPA-714. J Nucl Med 2017; 59:307-314. [DOI: 10.2967/jnumed.117.195396] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Accepted: 07/07/2017] [Indexed: 01/24/2023] Open
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Abdul Manan MAF, Cordes DB, Slawin AMZ, Bühl M, Liao VWY, Chua HC, Chebib M, O'Hagan D. The Synthesis and Evaluation of Fluoro-, Trifluoromethyl-, and Iodomuscimols as GABA Agonists. Chemistry 2017; 23:10848-10852. [DOI: 10.1002/chem.201701443] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Indexed: 02/04/2023]
Affiliation(s)
| | - David B. Cordes
- EaStCHEM School of Chemistry; University of St Andrews; North Haugh St Andrews KY16 9ST UK
| | - Alexandra M. Z. Slawin
- EaStCHEM School of Chemistry; University of St Andrews; North Haugh St Andrews KY16 9ST UK
| | - Michael Bühl
- EaStCHEM School of Chemistry; University of St Andrews; North Haugh St Andrews KY16 9ST UK
| | - Vivian W. Y. Liao
- Faculty of Pharmacy; The University of Sydney; Sydney, New South Wales 2006 Australia
| | - Han. C. Chua
- Faculty of Pharmacy; The University of Sydney; Sydney, New South Wales 2006 Australia
| | - Mary Chebib
- Faculty of Pharmacy; The University of Sydney; Sydney, New South Wales 2006 Australia
| | - David O'Hagan
- EaStCHEM School of Chemistry; University of St Andrews; North Haugh St Andrews KY16 9ST UK
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A single-scan protocol for absolute D2/3 receptor quantification with [123I]IBZM SPECT. Neuroimage 2017; 147:461-472. [DOI: 10.1016/j.neuroimage.2016.12.050] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Revised: 11/24/2016] [Accepted: 12/18/2016] [Indexed: 11/19/2022] Open
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Dumas N, Moulin-Sallanon M, Fender P, Tournier BB, Ginovart N, Charnay Y, Millet P. In Vivo Quantification of 5-HT2A Brain Receptors in Mdr1a KO Rats with 123I-R91150 Single-Photon Emission Computed Tomography. Mol Imaging 2016; 14. [PMID: 26105563 DOI: 10.2310/7290.2015.00006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Our goal was to identify suitable image quantification methods to image 5-hydroxytryptamine2A (5-HT2A) receptors in vivo in Mdr1a knockout (KO) rats (i.e., P-glycoprotein KO) using 123I-R91150 single-photon emission computed tomography (SPECT). The 123I-R91150 binding parameters estimated with different reference tissue models (simplified reference tissue model [SRTM], Logan reference tissue model, and tissue ratio [TR] method) were compared to the estimates obtained with a comprehensive three-tissue/seven-parameter (3T/7k)-based model. The SRTM and Logan reference tissue model estimates of 5-HT2A receptor (5-HT2AR) nondisplaceable binding potential (BPND) correlated well with the absolute receptor density measured with the 3T/7k gold standard (r > .89). Quantification of 5-HT2AR using the Logan reference tissue model required at least 90 minutes of scanning, whereas the SRTM required at least 110 minutes. The TR method estimates were also highly correlated to the 5-HT2AR density (r > .91) and only required a single 20-minute scan between 100 and 120 minutes postinjection. However, a systematic overestimation of the BPND values was observed. The Logan reference tissue method is more convenient than the SRTM for the quantification of 5-HT2AR in Mdr1a KO rats using 123I-R91150 SPECT. The TR method is an interesting and simple alternative, despite its bias, as it still provides a valid index of 5-HT2AR density.
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5-HT2A receptor SPECT imaging with [¹²³I]R91150 under P-gp inhibition with tariquidar: More is better? Nucl Med Biol 2015; 43:81-88. [PMID: 26454782 DOI: 10.1016/j.nucmedbio.2015.09.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Revised: 08/18/2015] [Accepted: 09/05/2015] [Indexed: 12/11/2022]
Abstract
INTRODUCTION Pharmacological P-glycoprotein (P-gp) inhibition with tariquidar (TQD) is considered a promising strategy for the augmentation of radiotracer brain uptake. However, a region-dependent effect may compromise the robustness of quantitative studies. For this reason, we studied the effect of a TQD pretreatment on 5-HT2A imaging with [(123)I]R91150 and compared results with those obtained in Mdr1a knock-out (KO) rats. METHODS Ex vivo autoradiography was performed in TQD (15 mg/kg) pretreated wild-type (WT-TQD), Mdr1a knock-out (KO) and untreated WT rats for Specific Binding Ratio (SBR) estimation. In vivo dynamic SPECT imaging with serial arterial blood sampling was performed in the former two groups of rats and kinetic analysis was performed with a one tissue-compartment (1TC) model and the Specific Uptake Ratio (SUR). Results were analyzed statistically using repeated measures ANOVA. RESULTS SBR values differed between WT-TQD, Mdr1a KO and WT rats in a region-dependent manner (p<0.0001). In vivo brain uptake of radiotracer did not differ between groups. Similarly, kinetic analysis provided distribution volume (V(T)) values that did not differ significantly between groups. SUR binding potential (BPND) values from both groups highly correlated with corresponding V(T) (r=0.970, p<0.0001 and r=0.962, p<0.0001, respectively). However, SUR measured over averaged images between 100 and 120 min, using cerebellum as reference region, demonstrated values that were, by average, 2.99±0.53 times higher in the WT-TQD group, with the difference between groups being region-dependent (p<0.001). In addition, coefficient of variation of the SUR BPND values across brain regions was significantly higher in the WT-TQD rats (41.25%±9.63% versus 11.13%±5.59%, p<0.0001). CONCLUSION P-gp inhibition with TQD leads to region-dependent effect in the rat brain, with probably sub-optimal effect in cerebellum. This warrants attention when it is used as a reference region for quantitative studies.
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Tsartsalis S, Moulin-Sallanon M, Dumas N, Tournier BB, Ginovart N, Millet P. A Modified Simplified Reference Tissue Model for the Quantification of Dopamine D2/3Receptors with [18F]Fallypride Images. Mol Imaging 2014; 13. [DOI: 10.2310/7290.2014.00028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Stergios Tsartsalis
- From the Vulnerability Biomarkers Unit, Division of General Psychiatry, Department of Psychiatry, University Hospitals of Geneva, Geneva, Switzerland; Department of Psychiatry, University of Geneva, Geneva, Switzerland; and INSERM Unit 1039, J. Fourier University, La Tronche, France
| | - Marcelle Moulin-Sallanon
- From the Vulnerability Biomarkers Unit, Division of General Psychiatry, Department of Psychiatry, University Hospitals of Geneva, Geneva, Switzerland; Department of Psychiatry, University of Geneva, Geneva, Switzerland; and INSERM Unit 1039, J. Fourier University, La Tronche, France
| | - Noé Dumas
- From the Vulnerability Biomarkers Unit, Division of General Psychiatry, Department of Psychiatry, University Hospitals of Geneva, Geneva, Switzerland; Department of Psychiatry, University of Geneva, Geneva, Switzerland; and INSERM Unit 1039, J. Fourier University, La Tronche, France
| | - Benjamin B. Tournier
- From the Vulnerability Biomarkers Unit, Division of General Psychiatry, Department of Psychiatry, University Hospitals of Geneva, Geneva, Switzerland; Department of Psychiatry, University of Geneva, Geneva, Switzerland; and INSERM Unit 1039, J. Fourier University, La Tronche, France
| | - Nathalie Ginovart
- From the Vulnerability Biomarkers Unit, Division of General Psychiatry, Department of Psychiatry, University Hospitals of Geneva, Geneva, Switzerland; Department of Psychiatry, University of Geneva, Geneva, Switzerland; and INSERM Unit 1039, J. Fourier University, La Tronche, France
| | - Philippe Millet
- From the Vulnerability Biomarkers Unit, Division of General Psychiatry, Department of Psychiatry, University Hospitals of Geneva, Geneva, Switzerland; Department of Psychiatry, University of Geneva, Geneva, Switzerland; and INSERM Unit 1039, J. Fourier University, La Tronche, France
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