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Sabri O, Becker GA, Meyer PM, Hesse S, Wilke S, Graef S, Patt M, Luthardt J, Wagenknecht G, Hoepping A, Smits R, Franke A, Sattler B, Habermann B, Neuhaus P, Fischer S, Tiepolt S, Deuther-Conrad W, Barthel H, Schönknecht P, Brust P. First-in-human PET quantification study of cerebral α4β2* nicotinic acetylcholine receptors using the novel specific radioligand (−)-[ 18 F]Flubatine. Neuroimage 2015; 118:199-208. [DOI: 10.1016/j.neuroimage.2015.05.065] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Revised: 05/15/2015] [Accepted: 05/24/2015] [Indexed: 10/23/2022] Open
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Patt M, Becker GA, Grossmann U, Habermann B, Schildan A, Wilke S, Deuther-Conrad W, Graef S, Fischer S, Smits R, Hoepping A, Wagenknecht G, Steinbach J, Gertz HJ, Hesse S, Schönknecht P, Brust P, Sabri O. Evaluation of metabolism, plasma protein binding and other biological parameters after administration of (-)-[(18)F]Flubatine in humans. Nucl Med Biol 2014; 41:489-94. [PMID: 24768146 DOI: 10.1016/j.nucmedbio.2014.03.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Revised: 03/07/2014] [Accepted: 03/17/2014] [Indexed: 11/25/2022]
Abstract
INTRODUCTION (-)-[(18)F]Flubatine is a PET tracer with high affinity and selectivity for the nicotinic acetylcholine α4β2 receptor subtype. A clinical trial assessing the availability of this subtype of nAChRs was performed. From a total participant number of 21 Alzheimer's disease (AD) patients and 20 healthy controls (HCs), the following parameters were determined: plasma protein binding, metabolism and activity distribution between plasma and whole blood. METHODS Plasma protein binding and fraction of unchanged parent compound were assessed by ultracentrifugation and HPLC, respectively. The distribution of radioactivity (parent compound+metabolites) between plasma and whole blood was determined ex vivo at different time-points after injection by gamma counting after separation of whole blood by centrifugation into the cellular and non-cellular components. In additional experiments in vitro, tracer distribution between these blood components was assessed for up to 90min. RESULTS A fraction of 15%±2% of (-)-[(18)F]Flubatine was found to be bound to plasma proteins. Metabolic degradation of (-)-[(18)F]Flubatine was very low, resulting in almost 90% unchanged parent compound at 90min p.i. with no significant difference between AD and HC. The radioactivity distribution between plasma and whole blood changed in vivo only slightly over time from 0.82±0.03 at 3min p.i. to 0.87±0.03 at 270min p.i. indicating the contribution of only a small amount of metabolites. In vitro studies revealed that (-)-[(18)F]Flubatine was instantaneously distributed between cellular and non-cellular blood parts. DISCUSSION (-)-[(18)F]Flubatine exhibits very favourable characteristics for a PET radiotracer such as slow metabolic degradation and moderate plasma protein binding. Equilibrium of radioactivity distribution between plasma and whole blood is reached instantaneously and remains almost constant over time allowing both convenient sample handling and facilitated fractional blood volume contribution assessment.
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Affiliation(s)
- Marianne Patt
- Department of Nuclear Medicine, University of Leipzig, Liebigstrasse 18, D-04103 Leipzig, Germany.
| | - Georg A Becker
- Department of Nuclear Medicine, University of Leipzig, Liebigstrasse 18, D-04103 Leipzig, Germany
| | - Udo Grossmann
- Department of Nuclear Medicine, University of Leipzig, Liebigstrasse 18, D-04103 Leipzig, Germany
| | - Bernd Habermann
- Department of Nuclear Medicine, University of Leipzig, Liebigstrasse 18, D-04103 Leipzig, Germany
| | - Andreas Schildan
- Department of Nuclear Medicine, University of Leipzig, Liebigstrasse 18, D-04103 Leipzig, Germany
| | - Stephan Wilke
- Department of Nuclear Medicine, University of Leipzig, Liebigstrasse 18, D-04103 Leipzig, Germany
| | - Winnie Deuther-Conrad
- Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, Research Site Leipzig, Permoserstrasse 15, D-04318 Leipzig, Germany
| | - Susanne Graef
- Department of Psychiatry, University of Leipzig, Semmelweisstrasse 10, D-04103 Leipzig, Germany
| | - Steffen Fischer
- Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, Research Site Leipzig, Permoserstrasse 15, D-04318 Leipzig, Germany
| | - René Smits
- ABX advanced biochemical compounds GmbH, Heinrich-Glaeser-Strasse 10-14, D-01454 Radeberg, Germany
| | - Alexander Hoepping
- ABX advanced biochemical compounds GmbH, Heinrich-Glaeser-Strasse 10-14, D-01454 Radeberg, Germany
| | - Gudrun Wagenknecht
- Multimodal Image Processing, Central Institute ZEA-2-Electronic Systems, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany
| | - Jörg Steinbach
- Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, Research Site Leipzig, Permoserstrasse 15, D-04318 Leipzig, Germany
| | - Hermann-Josef Gertz
- Department of Psychiatry, University of Leipzig, Semmelweisstrasse 10, D-04103 Leipzig, Germany
| | - Swen Hesse
- Department of Nuclear Medicine, University of Leipzig, Liebigstrasse 18, D-04103 Leipzig, Germany; Integrated Research and Treatment Centre (IFB) Adiposity Diseases, Leipzig University Medical Centre, Leipzig, Germany
| | - Peter Schönknecht
- Department of Psychiatry, University of Leipzig, Semmelweisstrasse 10, D-04103 Leipzig, Germany
| | - Peter Brust
- Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, Research Site Leipzig, Permoserstrasse 15, D-04318 Leipzig, Germany
| | - Osama Sabri
- Department of Nuclear Medicine, University of Leipzig, Liebigstrasse 18, D-04103 Leipzig, Germany; Integrated Research and Treatment Centre (IFB) Adiposity Diseases, Leipzig University Medical Centre, Leipzig, Germany
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Nakao R, Amini N, Halldin C. Simultaneous Determination of Protein-Free and Total Positron Emission Tomography Radioligand Concentrations in Plasma Using High-Performance Frontal Analysis Followed by Mixed Micellar Liquid Chromatography: Application to [11C]PBR28 in Human Plasma. Anal Chem 2013; 85:8728-34. [DOI: 10.1021/ac401742v] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Ryuji Nakao
- Department
of Clinical Neuroscience, Center for Psychiatric
Research, Karolinska Institute, Stockholm, Sweden
| | - Nahid Amini
- Department
of Clinical Neuroscience, Center for Psychiatric
Research, Karolinska Institute, Stockholm, Sweden
| | - Christer Halldin
- Department
of Clinical Neuroscience, Center for Psychiatric
Research, Karolinska Institute, Stockholm, Sweden
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Lotfipour S, Mandelkern M, Alvarez-Estrada M, Brody AL. A single administration of low-dose varenicline saturates α4β2* nicotinic acetylcholine receptors in the human brain. Neuropsychopharmacology 2012; 37:1738-48. [PMID: 22395733 PMCID: PMC3358744 DOI: 10.1038/npp.2012.20] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2011] [Revised: 01/16/2012] [Accepted: 02/06/2012] [Indexed: 01/22/2023]
Abstract
The primary objective of this project was to determine the α4β2(*) nicotinic acetylcholine receptor (nAChR) occupancy in human brain of a single low dose of varenicline (0.5 mg), and to explore the relationship between receptor occupancy by varenicline and tobacco withdrawal symptoms ((*)denoting other putative nAChR subunits). Otherwise healthy smokers (n=9) underwent two positron emission tomography (PET) sessions with the selective α4β2(*) radioligand 2-FA. For the PET sessions, participants received either a low dose of varenicline (0.5 mg) or matching placebo pill (double-blind, random order) before imaging. For both sessions, participants received bolus plus continuous infusions of 2-FA, were scanned for 1 h after allowing the radiotracer to reach a steady state, smoked to satiety, and were scanned for 2 more hours. We estimated the fractional receptor occupancy by a single dose of varenicline (0.5 mg) and the corresponding varenicline dissociation constant (K(V)), along with the effect of low-dose varenicline, pill placebo, and smoking-to-satiety on withdrawal rating scales. The data are compatible with 100% occupancy of α4β2(*) nAChRs by a single dose of varenicline, with a 90% lower confidence limit of 89% occupancy for the thalamus and brainstem. The corresponding 90% upper limit on effective K(V) with respect to plasma varenicline was 0.49 nM. Smoking to satiety, but not low-dose varenicline, significantly reduced withdrawal symptoms. Our findings demonstrate that low-dose varenicline results in saturation of α4β2(*) nAChRs in the thalamus and brainstem without reducing withdrawal symptoms.
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Affiliation(s)
- Shahrdad Lotfipour
- Hatos Center for Neuropharmacology, Semel Institute, University of California, Los Angeles, CA, USA.
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Brody AL, Mandelkern MA, London ED, Khan A, Kozman D, Costello MR, Vellios EE, Archie MM, Bascom R, Mukhin AG. Effect of secondhand smoke on occupancy of nicotinic acetylcholine receptors in brain. ACTA ACUST UNITED AC 2011; 68:953-60. [PMID: 21536968 DOI: 10.1001/archgenpsychiatry.2011.51] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
CONTEXT Despite progress in tobacco control, secondhand smoke (SHS) exposure remains prevalent worldwide and is implicated in the initiation and maintenance of cigarette smoking. OBJECTIVE To determine whether moderate SHS exposure results in brain α(4)β(2)* nicotinic acetylcholine receptor (nAChR) occupancy. DESIGN, SETTING, AND PARTICIPANTS Positron emission tomography scanning and the radiotracer 2-[18F]fluoro-3-(2(S)azetidinylmethoxy) pyridine (also known as 2-[(18)F]fluoro-A-85380, or 2-FA) were used to determine α(4)β(2)* nAChR occupancy from SHS exposure in 24 young adult participants (11 moderately dependent cigarette smokers and 13 nonsmokers). Participants underwent two bolus-plus-continuous-infusion 2-FA positron emission tomography scanning sessions during which they sat in the passenger's seat of a car for 1 hour and either were exposed to moderate SHS or had no SHS exposure. The study took place at an academic positron emission tomography center. Main Outcome Measure Changes induced by SHS in 2-FA specific binding volume of distribution as a measure of α(4)β(2)* nAChR occupancy. RESULTS An overall multivariate analysis of variance using specific binding volume of distribution values revealed a significant main effect of condition (SHS vs control) (F(1,22) = 42.5, P < .001) but no between-group (smoker vs nonsmoker) effect. Exposure to SHS led to a mean 19% occupancy of brain α(4)β(2)* nAChRs (1-sample t test, 2-tailed, P < .001). Smokers had both a mean 23% increase in craving with SHS exposure and a correlation between thalamic α(4)β(2)* nAChR occupancy and craving alleviation with subsequent cigarette smoking (Spearman ρ = -0.74, P = .01). CONCLUSIONS Nicotine from SHS exposure results in substantial brain α(4)β(2)* nAChR occupancy in smokers and nonsmokers. Study findings suggest that such exposure delivers a priming dose of nicotine to the brain that contributes to continued cigarette use in smokers. This study has implications for both biological research into the link between SHS exposure and cigarette use and public policy regarding the need to limit SHS exposure in cars and other enclosed spaces.
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Affiliation(s)
- Arthur L Brody
- Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, USA.
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Kendziorra K, Wolf H, Meyer PM, Barthel H, Hesse S, Becker GA, Luthardt J, Schildan A, Patt M, Sorger D, Seese A, Gertz HJ, Sabri O. Decreased cerebral α4β2* nicotinic acetylcholine receptor availability in patients with mild cognitive impairment and Alzheimer's disease assessed with positron emission tomography. Eur J Nucl Med Mol Imaging 2010; 38:515-25. [PMID: 21069319 DOI: 10.1007/s00259-010-1644-5] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2010] [Accepted: 10/04/2010] [Indexed: 01/14/2023]
Abstract
PURPOSE Postmortem studies indicate a loss of nicotinic acetylcholine receptor (nAChRs) in Alzheimer's disease (AD). In order to establish whether these changes in the cholinergic system occur at an early stage of AD, we carried out positron emission tomography (PET) with a specific radioligand for the α4β2* nicotinic acetylcholine receptor (α4β2* nAChR) in patients with mild to moderate AD and in patients with amnestic mild cognitive impairment (MCI), who have a high risk to progress to AD. METHODS Nine patients with moderate AD, eight patients with MCI and seven age-matched healthy controls underwent 2-[(18)F]fluoro-3-(2(S)-azetidinylmethoxy)pyridine (2-[(18)F]FA-85380) PET. After coregistration with individual magnetic resonance imaging the binding potential (BP(ND)) of 2-[(18)F]FA-85380 was calculated using either the corpus callosum or the cerebellum as reference regions. PET data were analysed by region of interest analysis and by voxel-based analysis. RESULTS Both patients with AD and MCI showed a significant reduction in 2-[(18)F]FA-85380 BP(ND) in typical AD-affected brain regions. Thereby, the corpus callosum was identified as the most suitable reference region. The 2-[(18)F]FA-85380 BP(ND) correlated with the severity of cognitive impairment. Only MCI patients that converted to AD in the later course (n = 5) had a reduction in 2-[(18)F]FA-85380 BP(ND). CONCLUSION 2-[(18)F]FA-85380 PET appears to be a sensitive and feasible tool for the detection of a reduction in α4β2* nAChRs which seems to be an early event in AD. In addition, 2-[(18)F]FA-85380 PET might give prognostic information about a conversion from MCI to AD.
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Affiliation(s)
- Kai Kendziorra
- Department of Nuclear Medicine, University of Leipzig, Leipzig, Germany.
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Sabri O, Kendziorra K, Wolf H, Gertz HJ, Brust P. Acetylcholine receptors in dementia and mild cognitive impairment. Eur J Nucl Med Mol Imaging 2008; 35 Suppl 1:S30-45. [PMID: 18228017 DOI: 10.1007/s00259-007-0701-1] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
PURPOSE To clarify whether changes in the cholinergic transmission occur early in the course of Alzheimer's disease (AD), we carried out positron emission tomography (PET) with the radioligand 2-[(18)F]F-A-85380, which is supposed to be specific for alpha4beta2 nicotinic acetylcholine receptors (nAChRs). METHOD We included patients with moderate to severe AD and patients with amnestic mild cognitive impairment (MCI), presumed to present preclinical AD. RESULTS Both patients with AD and MCI showed significant reductions in alpha4beta2 nAChRs in brain regions typically affected by AD pathology. These findings indicate that a reduction in alpha4beta2 nAChRs occurs during early symptomatic stages of AD. The alpha4beta2 nAChR availability in these regions correlated with the severity of cognitive impairment, indicating a stage sensitivity of the alpha4beta2 nAChR status. CONCLUSION Together, our results provide evidence for the potential of 2-[(18)]F-A-85380 nAChR PET in the diagnosis of patients at risk for AD. Because of the extraordinary long acquisition time with 2-[(18)F]F-A-85380, we developed the new alpha4beta2 nAChR-specific radioligands (+)- and (-)-[(18)F]norchloro-fluoro-homoepibatidine (NCFHEB) and evaluated them preclinically. (-)-[(18)F]NCFHEB shows twofold higher brain uptake and significantly shorter acquisition times. Therefore, (-)-[(18)F]NCFHEB should be a suitable radioligand for larger clinical investigations.
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Affiliation(s)
- Osama Sabri
- Department of Nuclear Medicine, University of Leipzig, Stephanstrasse 11, Leipzig, Germany.
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Sorger D, Becker GA, Patt M, Schildan A, Grossmann U, Schliebs R, Seese A, Kendziorra K, Kluge M, Brust P, Mukhin AG, Sabri O. Measurement of the alpha4beta2* nicotinic acetylcholine receptor ligand 2-[(18)F]Fluoro-A-85380 and its metabolites in human blood during PET investigation: a methodological study. Nucl Med Biol 2007; 34:331-42. [PMID: 17383583 DOI: 10.1016/j.nucmedbio.2006.12.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2006] [Revised: 11/20/2006] [Accepted: 12/17/2006] [Indexed: 10/23/2022]
Abstract
2-[(18)F]fluoro-A-85380 (2-[(18)F]FA) is a new radioligand for noninvasive imaging of alpha4beta2* nicotinic acetylcholine receptors (nAChRs) by positron emission tomography (PET) in human brain. In most cases, quantification of 2-[(18)F]FA receptor binding involves measurement of free nonmetabolized radioligand concentration in blood. This requires an efficient and reliable method to separate radioactive metabolites from the parent compound. In the present study, three analytical methods, thin layer chromatography (TLC), high-performance liquid chromatography (HPLC) and solid phase extraction (SPE) have been tested. Reversed-phase TLC of deproteinized aqueous samples of plasma provides good estimates of 2-[(18)F]FA and its metabolites. However, because of the decreased radioactivity in plasma samples, this method can be used in humans over the first 2 h after radioligand injection only. Reliable quantification of the parent radioligand and its main metabolites was obtained using reversed-phase HPLC, followed by counting of eluted fractions in a well gamma counter. Three main and five minor metabolites of 2-[(18)F]FA were detected in human blood using this method. On average, the unchanged 2-[(18)F]FA fraction in plasma of healthy volunteers measured at 14, 60, 120, 240 and 420 min after radioligand injection was 87.3+/-2.2%, 74.4+/-3%, 68.8+/-5%, 62.3+/-8% and 61.0+/-8%, respectively. In patients with neurodegenerative disorders, the values corresponding to the three last time points were significantly lower. The fraction of nonmetabolized 2-[(18)F]FA in plasma determined using SPE did not differ significantly from that obtained by HPLC (+gamma counting) (n=73, r=.95). Since SPE is less time-consuming than HPLC and provides comparable results, we conclude that SPE appears to be the most suitable method for measurement of 2-[(18)F]FA parent fraction during PET investigations.
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Affiliation(s)
- Dietlind Sorger
- Department of Nuclear Medicine, University of Leipzig, Leipzig, 04103, Germany.
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