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Sultzer DL, Lim AC, Gordon HL, Yarns BC, Melrose RJ. Cholinergic receptor binding in unimpaired older adults, mild cognitive impairment, and Alzheimer's disease dementia. Alzheimers Res Ther 2022; 14:25. [PMID: 35130968 PMCID: PMC8819935 DOI: 10.1186/s13195-021-00954-w] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Accepted: 12/21/2021] [Indexed: 01/07/2023]
Abstract
BACKGROUND Cholinergic neurotransmitter system dysfunction contributes to cognitive impairment in Alzheimer's disease and other syndromes. However, the specific cholinergic mechanisms and brain structures involved, time course of alterations, and relationships with specific cognitive deficits are not well understood. METHODS This study included 102 older adults: 42 cognitively unimpaired (CU), 28 with mild cognitive impairment (MCI), and 32 with Alzheimer's disease (AD) dementia. Each participant underwent a neuropsychological assessment. Regional brain α4β2 nicotinic cholinergic receptor binding (VT/fp) was measured using 2-[18F]fluoro-3-(2(S)azetidinylmethoxy)pyridine (2FA) and PET imaging. Voxel-wise analyses of group differences were performed. Relationships between receptor binding and cognition, age, and cholinesterase inhibitor medication use were assessed using binding values in six prespecified regions of interest. RESULTS SPM analysis showed the group VT/fp binding differences in the bilateral entorhinal cortex, hippocampus, insula, anterior cingulate, thalamus, and basal ganglia (p < .05, FWE-corrected). Pairwise comparisons revealed lower binding in the AD group compared to the CU group in similar regions. Binding in the entorhinal cortex was lower in the MCI group than in the CU group; binding in the hippocampus was lower in the AD group than in the MCI group. AD participants taking cholinesterase inhibitor medication had lower 2FA binding in the bilateral hippocampus and thalamus compared to those not taking medication. In the CU group, age was negatively associated with 2FA binding in each region of interest (rs = - .33 to - .59, p < .05 for each, uncorrected). Attention, immediate recall, and delayed recall scores were inversely associated with 2FA binding in most regions across the full sample. In the combined group of CU and MCI participants, attention was inversely associated with 2FA binding in most regions, beyond the effect of hippocampal volume. CONCLUSIONS Nicotinic cholinergic receptor binding in specific limbic and subcortical regions is lower in MCI and further reduced in AD dementia, compared to CU older adults, and is related to cognitive deficits. Cognitive decline with age may be a consequence of reduced cholinergic receptor density or binding affinity that may also promote vulnerability to other Alzheimer's processes. Contemporary modification of the "cholinergic deficit" of aging and AD may reveal opportunities to prevent or improve clinical symptoms.
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Affiliation(s)
- David L. Sultzer
- grid.417119.b0000 0001 0384 5381Psychiatry/Mental Health Service, VA Greater Los Angeles Healthcare System, Los Angeles, CA USA ,grid.266093.80000 0001 0668 7243Department of Psychiatry and Human Behavior, School of Medicine, and Institute for Memory Impairments and Neurological Disorders (UCI MIND), University of California, Irvine, Irvine, CA USA
| | - Aaron C. Lim
- grid.417119.b0000 0001 0384 5381Psychiatry/Mental Health Service, VA Greater Los Angeles Healthcare System, Los Angeles, CA USA ,grid.42505.360000 0001 2156 6853Department of Family Medicine, USC Keck School of Medicine, Alhambra, CA USA
| | - Hailey L. Gordon
- grid.417119.b0000 0001 0384 5381Psychiatry/Mental Health Service, VA Greater Los Angeles Healthcare System, Los Angeles, CA USA ,grid.147455.60000 0001 2097 0344Biomedical Engineering Department, Carnegie Mellon University, Pittsburgh, PA USA
| | - Brandon C. Yarns
- grid.417119.b0000 0001 0384 5381Psychiatry/Mental Health Service, VA Greater Los Angeles Healthcare System, Los Angeles, CA USA ,grid.19006.3e0000 0000 9632 6718Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine at UCLA, Los Angeles, CA USA
| | - Rebecca J. Melrose
- grid.417119.b0000 0001 0384 5381Psychiatry/Mental Health Service, VA Greater Los Angeles Healthcare System, Los Angeles, CA USA ,grid.19006.3e0000 0000 9632 6718Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine at UCLA, Los Angeles, CA USA
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Sultzer DL, Melrose RJ, Riskin-Jones H, Narvaez TA, Veliz J, Ando TK, Juarez KO, Harwood DG, Brody AL, Mandelkern MA. Cholinergic Receptor Binding in Alzheimer Disease and Healthy Aging: Assessment In Vivo with Positron Emission Tomography Imaging. Am J Geriatr Psychiatry 2017; 25:342-353. [PMID: 28162919 DOI: 10.1016/j.jagp.2016.11.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Revised: 11/17/2016] [Accepted: 11/18/2016] [Indexed: 01/29/2023]
Abstract
OBJECTIVE To compare regional nicotinic cholinergic receptor binding in older adults with Alzheimer disease (AD) and healthy older adults in vivo and to assess relationships between receptor binding and clinical symptoms. METHODS Using cross-sectional positron emission tomography (PET) neuroimaging and structured clinical assessment, outpatients with mild to moderate AD (N = 24) and healthy older adults without cognitive complaints (C group; N = 22) were studied. PET imaging of α4β2* nicotinic cholinergic receptor binding using 2-[18F]fluoro-3-(2(S)azetidinylmethoxy)pyridine (2FA) and clinical measures of global cognition, attention/processing speed, verbal memory, visuospatial memory, and neuropsychiatric symptoms were used. RESULTS 2FA binding was lower in the AD group compared with the C group in the medial thalamus, medial temporal cortex, anterior cingulate, insula/opercula, inferior caudate, and brainstem (p < 0.05, corrected cluster), but binding was not associated with cognition. The C group had significant inverse correlations between 2FA binding in the thalamus (left: rs = -0.55, p = 0.008; right: rs = -0.50, p = 0.02; N = 22) and hippocampus (left: rs = -0.65, p = 0.001; right: rs = -0.55, p = 0.009; N = 22) and the Trails A score. The AD group had inverse correlation between 2FA binding in anterior cingulate (left: rs = -0.50, p = 0.01; right: rs = -0.50, p = 0.01; N = 24) and Neurobehavioral Rating Scale agitation/disinhibition factor score. CONCLUSION Cholinergic receptor binding is reduced in specific brain regions in mild to moderate AD and is related to neuropsychiatric symptoms. Among healthy older adults, lower receptor binding may be associated with slower processing speed. Cholinergic receptor binding in vivo may reveal links to other key brain changes associated with aging and AD and may provide a potential molecular treatment target.
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Affiliation(s)
- David L Sultzer
- Psychiatry/Mental Health Service, VA Greater Los Angeles Healthcare System, Los Angeles, CA; Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA.
| | - Rebecca J Melrose
- Psychiatry/Mental Health Service, VA Greater Los Angeles Healthcare System, Los Angeles, CA; Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA
| | - Hannah Riskin-Jones
- Psychiatry/Mental Health Service, VA Greater Los Angeles Healthcare System, Los Angeles, CA
| | - Theresa A Narvaez
- Psychiatry/Mental Health Service, VA Greater Los Angeles Healthcare System, Los Angeles, CA
| | - Joseph Veliz
- Psychiatry/Mental Health Service, VA Greater Los Angeles Healthcare System, Los Angeles, CA
| | - Timothy K Ando
- Psychiatry/Mental Health Service, VA Greater Los Angeles Healthcare System, Los Angeles, CA
| | - Kevin O Juarez
- Psychiatry/Mental Health Service, VA Greater Los Angeles Healthcare System, Los Angeles, CA
| | - Dylan G Harwood
- Psychiatry/Mental Health Service, VA Greater Los Angeles Healthcare System, Los Angeles, CA; Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA
| | - Arthur L Brody
- Psychiatry/Mental Health Service, VA Greater Los Angeles Healthcare System, Los Angeles, CA; Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, CA
| | - Mark A Mandelkern
- Imaging Service, VA Greater Los Angeles Healthcare Center, Los Angeles, CA; Department of Physics, University of California-Irvine, Irvine, CA
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Nicotinic acetylcholine receptor availability in cigarette smokers: effect of heavy caffeine or marijuana use. Psychopharmacology (Berl) 2016; 233:3249-57. [PMID: 27370018 PMCID: PMC4982797 DOI: 10.1007/s00213-016-4367-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Accepted: 06/16/2016] [Indexed: 12/26/2022]
Abstract
RATIONALE Upregulation of α4β2* nicotinic acetylcholine receptors (nAChRs) is one of the most well-established effects of chronic cigarette smoking on the brain. Prior research by our group gave a preliminary indication that cigarette smokers with concomitant use of caffeine or marijuana have altered nAChR availability. OBJECTIVE We sought to determine if smokers with heavy caffeine or marijuana use have different levels of α4β2* nAChRs than smokers without these drug usages. METHODS One hundred and one positron emission tomography (PET) scans, using the radiotracer 2-FA (a ligand for β2*-containing nAChRs), were obtained from four groups of males: non-smokers without heavy caffeine or marijuana use, smokers without heavy caffeine or marijuana use, smokers with heavy caffeine use (mean four coffee cups per day), and smokers with heavy marijuana use (mean 22 days of use per month). Total distribution volume (Vt/fp) was determined for the brainstem, prefrontal cortex, and thalamus, as a measure of nAChR availability. RESULTS A significant between-group effect was found, resulting from the heavy caffeine and marijuana groups having the highest Vt/fp values (especially for the brainstem and prefrontal cortex), followed by smokers without such use, followed by non-smokers. Direct between-group comparisons revealed significant differences for Vt/fp values between the smoker groups with and without heavy caffeine or marijuana use. CONCLUSIONS Smokers with heavy caffeine or marijuana use have higher α4β2* nAChR availability than smokers without these drug usages. These findings are likely due to increased nicotine exposure but could also be due to an interaction on a cellular/molecular level.
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Horti AG, Wong DF. Clinical Perspective and Recent Development of PET Radioligands for Imaging Cerebral Nicotinic Acetylcholine Receptors. PET Clin 2016; 4:89-100. [PMID: 20046884 DOI: 10.1016/j.cpet.2009.04.014] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Lodge MA, Holt DP, Kinahan PE, Wong DF, Wahl RL. Performance assessment of a NaI(Tl) gamma counter for PET applications with methods for improved quantitative accuracy and greater standardization. EJNMMI Phys 2015; 2. [PMID: 26046011 PMCID: PMC4452125 DOI: 10.1186/s40658-015-0114-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Background Although NaI(Tl) gamma counters play an important role in many quantitative positron emission tomography (PET) protocols, their calibration for positron-emitting samples has not been standardized across imaging sites. In this study, we characterized the operational range of a gamma counter specifically for positron-emitting radionuclides, and we assessed the role of traceable 68Ge/68Ga sources for standardizing system calibration. Methods A NaI(Tl) gamma counter was characterized with respect to count rate performance, adequacy of detector shielding, system stability, and sample volume effects using positron-emitting radionuclides (409- to 613-keV energy window). System efficiency was measured using 18F and compared with corresponding data obtained using a long-lived 68Ge/68Ga source that was implicitly traceable to a national standard. Results One percent count loss was measured at 450 × 103 counts per minute. Penetration of the detector shielding by 511-keV photons gave rise to a negligible background count rate. System stability tests showed a coefficient of variation of 0.13% over 100 days. For a sample volume of 4 mL, the efficiencies relative to those at 0.1 mL were 0.96, 0.94, 0.91, 0.78, and 0.72 for 11C, 18F, 125I, 99mTc, and 51Cr, respectively. The efficiency of a traceable 68Ge/68Ga source was 30.1% ± 0.07% and was found to be in close agreement with the efficiency for 18F after consideration of the different positron fractions. Conclusions Long-lived 68Ge/68Ga reference sources, implicitly traceable to a national metrology institute, can aid standardization of gamma counter calibration for 18F. A characteristic feature of positron emitters meant that accurate calibration could be maintained over a wide range of sample volumes by using a narrow energy window centered on the 511-keV peak.
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Affiliation(s)
- Martin A Lodge
- Division of Nuclear Medicine, The Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Daniel P Holt
- Division of Nuclear Medicine, The Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Paul E Kinahan
- Department of Radiology, University of Washington, Seattle, WA, USA
| | - Dean F Wong
- Division of Nuclear Medicine, The Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Richard L Wahl
- Department of Radiology, Washington University School of Medicine, St. Louis, MO, USA
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Storage S, Mandelkern MA, Phuong J, Kozman M, Neary MK, Brody AL. A positive relationship between harm avoidance and brain nicotinic acetylcholine receptor availability. Psychiatry Res 2013; 214:415-21. [PMID: 24148908 PMCID: PMC3851586 DOI: 10.1016/j.pscychresns.2013.07.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2012] [Revised: 06/22/2013] [Accepted: 07/25/2013] [Indexed: 01/28/2023]
Abstract
Prior research indicates that disturbance of cholinergic neurotransmission reduces anxiety, leading to the hypothesis that people with heightened cholinergic function have a greater tendency toward anxiety-like and/or harm-avoidant behavior. We sought to determine if people with elevated levels of harm avoidance (HA), a dimension of temperament from the Temperament and Character Inventory (TCI), have high α4β2* nicotinic acetylcholine receptor (nAChR) availability. Healthy adults (n=105; 47 non-smokers and 58 smokers) underwent bolus-plus-continuous infusion positron emission tomography (PET) scanning using the radiotracer 2-[18F]fluoro-3-(2(S)azetidinylmethoxy) pyridine (abbreviated as 2-FA). During the uptake period of 2-FA, participants completed the TCI. The central study analysis revealed a significant association between total HA and mean nAChR availability, with higher total HA scores being linked with greater nAChR availability. In examining HA subscales, both 'Fear of Uncertainty' and 'Fatigability' were significant, based on higher levels of these characteristics being associated with greater nAChR availabilities. This study adds to a growing body of knowledge concerning the biological basis of personality and may prove useful in understanding the pathophysiology of psychiatric disorders (such as anxiety disorders) that have similar characteristics to HA. Study findings may indicate that heightened cholinergic neurotransmission is associated with increased anxiety-like traits.
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Affiliation(s)
- Steven Storage
- UCLA School of Medicine, Los Angeles, California, USA,Department of Research, VA Greater Los Angeles Healthcare System, Los Angeles, CA, USA
| | - Mark A. Mandelkern
- Department of Research, VA Greater Los Angeles Healthcare System, Los Angeles, CA, USA,Department of Physics, University of California at Irvine, California, USA
| | - Jonathan Phuong
- Department of Research, VA Greater Los Angeles Healthcare System, Los Angeles, CA, USA
| | - Maggie Kozman
- Department of Research, VA Greater Los Angeles Healthcare System, Los Angeles, CA, USA
| | - Meaghan K. Neary
- Department of Research, VA Greater Los Angeles Healthcare System, Los Angeles, CA, USA
| | - Arthur L. Brody
- UCLA School of Medicine, Los Angeles, California, USA,Department of Research, VA Greater Los Angeles Healthcare System, Los Angeles, CA, USA,Department of Psychiatry, VA Greater Los Angeles Healthcare System, Los Angeles, CA, USA,Corresponding author at: UCLA Department of Psychiatry & Biobehavioral Sciences 300 UCLA Medical Plaza, Suite 2200 Los Angeles, CA 90095. Tel.: +310 268 4778; fax: +310 206 2802.
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Peyronneau MA, Saba W, Goutal S, Kuhnast B, Dollé F, Bottlaender M, Valette H. [(18)F]Fallypride: metabolism studies and quantification of the radiotracer and its radiometabolites in plasma using a simple and rapid solid-phase extraction method. Nucl Med Biol 2013; 40:887-95. [PMID: 23891202 DOI: 10.1016/j.nucmedbio.2013.06.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Revised: 05/22/2013] [Accepted: 06/13/2013] [Indexed: 11/16/2022]
Abstract
INTRODUCTION [(18)F]Fallypride, a fluorinated and substituted benzamide with high affinity for D2/D3 receptors, is a useful PET radioligand for the study of striatal/extrastriatal areas. Since [(18)F]fallypride is extensively metabolized in vivo and since PET examinations are long lasting in humans, the rapid measurement of the unchanged radiotracer in plasma is essential for the quantification of images. The present study aims: i) to evaluate if the radiometabolites of [(18)F]fallypride cross the blood-brain barrier in rodents, ii) to identify these radiometabolites in baboon plasma and iii) to develop a rapid solid phase extraction method (SPE) suitable for human applications to quantify both [(18)F]fallypride and its radiometabolites in plasma. METHODS The metabolites P450-dependant in rat and human liver microsomes were characterized by LC-MS-MS and compared to those detected in vivo. Sequential solvent elution on Oasis®-MCX-SPE cartridges was used to quantify [(18)F]fallypride and its radiometabolites. RESULT In rat microsomal incubations, five metabolites generated upon N/O-dealkylation or hydroxylation at the pyrrolidine and/or at the benzamide moiety were identified. No radiometabolite was detected in the rat brain. N-dealkylated and hydroxylated derivatives were detected in human microsomal incubations as well as in baboon plasma. The use of SPE (total recovery 100.2%± 2.8%, extraction yield 95.5%± 0.3%) allowed a complete separation of [(18)F]fallypride from its radiometabolites in plasma and evaluate [(18)F]fallypride at 150 min pi to be 22%± 5% of plasma radioactivity. CONCLUSIONS The major in vivo radiometabolites of [(18)F]fallypride were produced by N-dealkylation and hydroxylation. Allowing the rapid analysis of multiple plasma samples, SPE is a method of choice for the determination of [(18)F]fallypride until late images required for quantitative PET imaging in humans.
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Wong DF, Kuwabara H, Kim J, Brasic JR, Chamroonrat W, Gao Y, Valentine H, Willis W, Mathur A, McCaul ME, Wand G, Gean EG, Dannals RF, Horti AG. PET imaging of high-affinity α4β2 nicotinic acetylcholine receptors in humans with 18F-AZAN, a radioligand with optimal brain kinetics. J Nucl Med 2013; 54:1308-14. [PMID: 23801676 DOI: 10.2967/jnumed.112.108001] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
UNLABELLED We evaluated (-)-2-(6-[(18)F]fluoro-2,3'-bipyridin-5'-yl)-7-methyl-7-aza-bicyclo[2.2.1]heptane ((18)F-AZAN), a novel radiotracer that binds to α4β2 nicotinic acetylcholine receptors (α4β2-nAChRs) and shows high specific binding and rapid and reversible kinetics in the baboon and human brain. METHODS We tested safety tolerability and test-retest reliability (n = 5) and proposed initial quantification of (18)F-AZAN receptors in 3 healthy human subjects who had nicotine exposure and 9 who did not. We also present a receptor blocking study in a nicotine subject dosed with the α4β2-nAChR-selective partial agonist varenicline. RESULTS Radiation dosimetry PET/CT experiments indicated that most human organs received doses between 0.008 and 0.015 mSv/MBq, with an effective dose of approximately 0.014 mSv/MBq. The tracer rapidly entered the brain, and the peak was reached before 20 min, even for thalamus. Ninety-minute scans were sufficient for (18)F-AZAN to obtain the ratio at equilibrium of specifically bound radioligand to nondisplaceable radioligand in tissue (BPND) using plasma reference graphical analysis, which showed excellent reproducibility of BPND (test-retest variability < 10%) in the nAChR-rich brain regions. Regional plasma reference graphical analysis BP(ND) values exceeded 2 in the midbrain tegmental nuclei, lateral geniculate body, and thalamus for nonsmokers (n = 9) but were less than 1 in the nAChR-poor brain regions. There was a dramatic reduction of (18)F-AZAN brain uptake in smokers and varenicline-treated subjects. CONCLUSION (18)F-AZAN is a highly specific, safe, and effective PET radioligand for human subjects that requires only 90 min of PET scanning to estimate high-affinity α4β2-nAChR in the living human brain.
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Affiliation(s)
- Dean F Wong
- Department of Radiology, School of Medicine, Johns Hopkins University, Baltimore, Maryland, USA.
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Abstract
One-third of smokers primarily use menthol cigarettes and usage of these cigarettes leads to elevated serum nicotine levels and more difficulty quitting in standard treatment programmes. Previous brain imaging studies demonstrate that smoking (without regard to cigarette type) leads to up-regulation of β(2)*-containing nicotinic acetylcholine receptors (nAChRs). We sought to determine if menthol cigarette usage results in greater nAChR up-regulation than non-menthol cigarette usage. Altogether, 114 participants (22 menthol cigarette smokers, 41 non-menthol cigarette smokers and 51 non-smokers) underwent positron emission tomography scanning using the α(4)β(2)* nAChR radioligand 2-[(18)F]fluoro-A-85380 (2-FA). In comparing menthol to non-menthol cigarette smokers, an overall test of 2-FA total volume of distribution values revealed a significant between-group difference, resulting from menthol smokers having 9-28% higher α(4)β(2)* nAChR densities than non-menthol smokers across regions. In comparing the entire group of smokers to non-smokers, an overall test revealed a significant between-group difference, resulting from smokers having higher α(4)β(2)* nAChR levels in all regions studied (36-42%) other than thalamus (3%). Study results demonstrate that menthol smokers have greater up-regulation of nAChRs than non-menthol smokers. This difference is presumably related to higher nicotine exposure in menthol smokers, although other mechanisms for menthol influencing receptor density are possible. These results provide additional information about the severity of menthol cigarette use and may help explain why these smokers have more trouble quitting in standard treatment programmes.
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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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Brašić JR, Cascella N, Kumar A, Zhou Y, Hilton J, Raymont V, Crabb A, Guevara MR, Horti AG, Wong DF. Positron emission tomography experience with 2-[¹⁸F]fluoro-3-(2(S)-azetidinylmethoxy)pyridine (2-[¹⁸F]FA) in the living human brain of smokers with paranoid schizophrenia. Synapse 2012; 66:352-68. [PMID: 22169936 PMCID: PMC3445266 DOI: 10.1002/syn.21520] [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] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Accepted: 11/18/2011] [Indexed: 11/10/2022]
Abstract
Utilizing postmortem data (Breese et al. [2000] Neuropsychopharmacology 23:351-364), we hypothesized that the densities of high-affinity neuronal α4β2 nicotinic acetylcholine receptors (nAChRs) in the brain exist in a continuum from highest to lowest as follows: smokers without schizophrenia > smokers with schizophrenia > nonsmokers without schizophrenia > nonsmokers with schizophrenia. Application of the Kruskal-Wallis Test (Statacorp, 2003) to the postmortem data (Breese et al. [2000] Neuropsychopharmacology 23:351-364) confirmed the hypothesized order in the cortex and the hippocampus and attained significance in the caudate and the thalamus. Positron emission tomography (PET) was performed for 60 min at 6 h after the intravenous administration of 444 megabequerels [MBq] (12 mCi) 2-[¹⁸F]fluoro-3-(2(S)-azetidinylmethoxy)pyridine (2-[¹⁸F]FA), a radiotracer for high-affinity neuronal α4β2 nAChRs, as a bolus plus continuous infusion to 10 adults (seven men and three women) (six smokers including five with paranoid schizophrenia and four nonsmokers) ranging in age from 22 to 56 years (mean 40.1, standard deviation 13.6). The thalamic nondisplaceable binding potential (BP(ND) ) was 1.32 ± 0.19 (mean ± standard deviation) for healthy control nonsmokers; 0.50 ± 0.19 for smokers with paranoid schizophrenia; and 0.51 for the single smoker without paranoid schizophrenia. The thalamic BP(ND) s of nonsmokers were significantly higher than those of smokers who smoked cigarettes a few hours before the scans (P = 0.0105) (StataCorp, 2003), which was likely due to occupancy of nAChRs by inhaled nicotine in smokers. Further research is needed to rule out the effects of confounding variables.
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Affiliation(s)
- James Robert Brašić
- Division of Nuclear Medicine, The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Johns Hopkins Outpatient Center, Baltimore, Maryland 21287-0807, 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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Metabolite analysis of [18F]Florbetaben (BAY 94-9172) in human subjects: a substudy within a proof of mechanism clinical trial. J Radioanal Nucl Chem 2010. [DOI: 10.1007/s10967-010-0514-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Brasić JR, Zhou Y, Musachio JL, Hilton J, Fan H, Crabb A, Endres CJ, Reinhardt MJ, Dogan AS, Alexander M, Rousset O, Maris MA, Galecki J, Nandi A, Wong DF. Single photon emission computed tomography experience with (S)-5-[(123)I]iodo-3-(2-azetidinylmethoxy)pyridine in the living human brain of smokers and nonsmokers. Synapse 2009; 63:339-58. [PMID: 19140167 PMCID: PMC2766259 DOI: 10.1002/syn.20611] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
(S)-5-[(123)I]iodo-3-(2-azetidinylmethoxy)pyridine (5-[(123)I]IA), a novel potent radioligand for high-affinity alpha4beta2* neuronal nicotinic acetylcholine receptors (nAChRs), provides a means to evaluate the density and the distribution of nAChRs in the living human brain. We sought in healthy adult smokers and nonsmokers to (1) evaluate the safety, tolerability, and efficacy of 5-[(123)I]IA in an open nonblind trial and (2) to estimate the density and the distribution of alpha(4)beta(2)* nAChRs in the brain. Single photon emission computed tomography (SPECT) was performed for 5 h after the i.v. administration of approximately 0.001 microg/kg ( approximately 10 mCi) 5-[(123)I]IA. Blood pressure, heart rate, and neurobehavioral status were monitored before, during, and after the administration of 5-[(123)I]IA to 12 healthy adults (8 men and 4 women) (6 smokers and 6 nonsmokers) ranging in age from 19 to 46 years (mean = 28.25, standard deviation = 8.20). High plasma-nicotine level was significantly associated with low 5-[(123)I]IA binding in: (1) the caudate head, the cerebellum, the cortex, and the putamen, utilizing both the Sign and Mann-Whitney U-tests; (2) the fusiform gyrus, the hippocampus, the parahippocampus, and the pons utilizing the Mann-Whitney U-test; and (3) the thalamus utilizing the Sign test. We conclude that 5-[(123)I]IA is a safe, well-tolerated, and effective pharmacologic agent for human subjects to estimate high-affinity alpha4/beta2 nAChRs in the living human brain.
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Affiliation(s)
- James Robert Brasić
- Division of Nuclear Medicine, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA.
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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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Brust P, Patt JT, Deuther-Conrad W, Becker G, Patt M, Schildan A, Sorger D, Kendziorra K, Meyer P, Steinbach J, Sabri O. In vivo measurement of nicotinic acetylcholine receptors with [18F]norchloro-fluoro-homoepibatidine. Synapse 2008; 62:205-18. [PMID: 18088060 DOI: 10.1002/syn.20480] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Functional changes of nicotinic acetylcholine receptors (nAChR) are important during age-related neuronal degeneration. Recent studies demonstrate the applicability of the nAChR ligand 2-[(18)F]F-A-85380 for neuroimaging of patients with dementias. However, its binding kinetics demands a 7-h acquisition time limiting its practicality for clinical PET studies. Thus, the authors developed [(18)F]norchloro-fluoro-homoepibatidine ([(18)F]NCFHEB) for nAChR imaging. The kinetics of the two enantiomers of [(18)F]NCFHEB were compared with 2-[(18)F]F-A85380 in porcine brain to evaluate their potential for human neuroimaging. Twenty-four juvenile female pigs were studied with PET using [(18)F]NCFHEB. Nine animals received an additional i.v. injection (1 mg/kg) of the nAChR agonist A81418 before radiotracer administration followed by infusion (2 mg/kg/7h) thereafter. Several compartment models were applied for quantification. (-)- and (+)-[(18)F]NCFHEB showed a twofold to threefold higher brain uptake than 2-[(18)F]F-A-85380. All three radiotracers displayed spatially heterogeneous binding kinetics in regions with high, moderate, or low specific binding. The equilibrium of specific binding of (-)-[(18)F]NCFHEB was reached earlier than that of (+)-[(18)F]NCFHEB or 2-[(18)F]F-A85380. Continuous administration of the nAChR agonist A81418 inhibited the specific binding of (-)- and (+)-[(18)F]NCFHEB but not of 2-[(18)F]F-A85380. The peripheral metabolism of (+)-[(18)F]NCFHEB proceeded somewhat slower than that of the other radiotracers. Both enantiomers of [(18)F]NCFHEB are appropriate radiotracers for neuroimaging of nAChR in pigs. Their binding profile in vivo appears to be more selective than that of 2-[(18)F]F-A85380. (-)-[(18)F]NCFHEB offers a faster equilibrium of specific binding than 2-[(18)F]F-A85380.
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Affiliation(s)
- Peter Brust
- Department of Radiopharmacy, Institute of Interdisciplinary Isotope Research, Permoserstrasse 15, Leipzig, Germany.
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