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Thentu JB, Bhyrapuneni G, Padala NP, Chunduru P, Pantangi HR, Nirogi R. Evaluation of monoamine oxidase A and B type enzyme occupancy using non-radiolabelled tracers in rat brain. Neurochem Int 2021; 145:105006. [PMID: 33636211 DOI: 10.1016/j.neuint.2021.105006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 02/18/2021] [Accepted: 02/18/2021] [Indexed: 11/18/2022]
Abstract
Monoamine oxidase (MAO) enzymes, type A and B metabolise the amine neurotransmitters of the body. Selective inhibition of either enzyme is an approach for treating neurodegenerative and stress-induced disorders, and inhibition of an enzyme is proportional to the binding of the MAO inhibitor. Conventionally, the binding of test compounds to enzymes is assessed by radiolabelled ligands in ex vivo and in vivo occupancy assays. Regulatory restrictions and turnaround time are the limitations of the methods that use radiolabelled ligands. But the use of non-radiolabelled tracers and sensitive mass spectrometry (LC-MS/MS) based assays accelerated the determination of target occupancy in pre-clinical species. A report on use of non-radiolabelled ligand in in vivo MAO occupancy assay is not available. The objectives of the present study were to optimise non-radiolabelled harmine and deprenyl as selective tracers in MAO-A and MAO-B occupancy assays and evaluate MAO occupancy of test compounds in rat brain. Tracer optimisation resulted in a detectable, stable, and low ratio (<3.0) of tracer concentrations between any two brain tissues. In occupancy assay, tracer was intravenously administered (10 μg/kg, harmine or 60 μg/kg, L-deprenyl) after the treatment with test compound (clorgyline or tranylcypromine or pargyline or phenelzine or thioperamide). Specific brain tissues were isolated at a defined interval and tracer concentrations were quantified using LC-MS/MS method. Pre-treatment with MAO inhibitors resulted in a decrease (maximum, 80-85%) in harmine or an increase (maximum, 85-300%) in L-deprenyl concentrations. But we considered the change in tracer concentration, relative to the vehicle and positive control groups to calculate MAO occupancy. The observed selectivity and ratio of occupancies (ED50) of test compound towards MAO-A and MAO-B are comparable with the results from in vitro radiolabelled ligand-based inhibition assay. The results demonstrated the application of these non-radiolabelled tracers as suitable pre-clinical tools to determine MAO occupancy.
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Affiliation(s)
- Jagadeesh Babu Thentu
- Discovery Research, Suven Life Sciences Ltd, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad, India.
| | - Gopinadh Bhyrapuneni
- Discovery Research, Suven Life Sciences Ltd, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad, India.
| | - Nagasurya Prakash Padala
- Discovery Research, Suven Life Sciences Ltd, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad, India.
| | - Prathyusha Chunduru
- Discovery Research, Suven Life Sciences Ltd, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad, India.
| | - Hanumanth Rao Pantangi
- Discovery Research, Suven Life Sciences Ltd, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad, India.
| | - Ramakrishna Nirogi
- Discovery Research, Suven Life Sciences Ltd, Serene Chambers, Road-5, Avenue-7, Banjara Hills, Hyderabad, India.
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Sex and the serotonergic underpinnings of depression and migraine. HANDBOOK OF CLINICAL NEUROLOGY 2020; 175:117-140. [PMID: 33008520 DOI: 10.1016/b978-0-444-64123-6.00009-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Most psychiatric disorders demonstrate sex differences in their prevalence and symptomatology, and in their response to treatment. These differences are particularly pronounced in mood disorders. Differences in sex hormone levels are among the most overt distinctions between males and females and are thus an intuitive underpinning for these clinical observations. In fact, treatment with estrogen and testosterone was shown to exert antidepressant effects, which underscores this link. Changes to monoaminergic signaling in general, and serotonergic transmission in particular, are understood as central components of depressive pathophysiology. Thus, modulation of the serotonin system may serve as a mechanism via which sex hormones exert their clinical effects in mental health disorders. Over the past 20 years, various experimental approaches have been applied to identify modes of influence of sex and sex hormones on the serotonin system. This chapter provides an overview of different molecular components of the serotonin system, followed by a review of studies performed in animals and in humans with the purpose of elucidating sex hormone effects. Particular emphasis will be placed on studies performed with positron emission tomography, a method that allows for human in vivo molecular imaging and, therefore, assessment of effects in a clinically representative context. The studies addressed in this chapter provide a wealth of information on the interaction between sex, sex hormones, and serotonin in the brain. In general, they offer evidence for the concept that the influence of sex hormones on various components of the serotonin system may serve as an underpinning for the clinical effects these hormones demonstrate.
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Zanderigo F, D’Agostino AE, Joshi N, Schain M, Kumar D, Parsey RV, DeLorenzo C, Mann JJ. [11C]Harmine Binding to Brain Monoamine Oxidase A: Test-Retest Properties and Noninvasive Quantification. Mol Imaging Biol 2018; 20:667-681. [DOI: 10.1007/s11307-018-1165-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Rotstein BH, Liang SH, Placzek MS, Hooker JM, Gee AD, Dollé F, Wilson AA, Vasdev N. (11)C[double bond, length as m-dash]O bonds made easily for positron emission tomography radiopharmaceuticals. Chem Soc Rev 2016; 45:4708-26. [PMID: 27276357 PMCID: PMC5000859 DOI: 10.1039/c6cs00310a] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The positron-emitting radionuclide carbon-11 ((11)C, t1/2 = 20.3 min) possesses the unique potential for radiolabeling of any biological, naturally occurring, or synthetic organic molecule for in vivo positron emission tomography (PET) imaging. Carbon-11 is most often incorporated into small molecules by methylation of alcohol, thiol, amine or carboxylic acid precursors using [(11)C]methyl iodide or [(11)C]methyl triflate (generated from [(11)C]carbon dioxide or [(11)C]methane). Consequently, small molecules that lack an easily substituted (11)C-methyl group are often considered to have non-obvious strategies for radiolabeling and require a more customized approach. [(11)C]Carbon dioxide itself, [(11)C]carbon monoxide, [(11)C]cyanide, and [(11)C]phosgene represent alternative reactants to enable (11)C-carbonylation. Methodologies developed for preparation of (11)C-carbonyl groups have had a tremendous impact on the development of novel PET tracers and provided key tools for clinical research. (11)C-Carbonyl radiopharmaceuticals based on labeled carboxylic acids, amides, carbamates and ureas now account for a substantial number of important imaging agents that have seen translation to higher species and clinical research of previously inaccessible targets, which is a testament to the creativity, utility and practicality of the underlying radiochemistry.
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Affiliation(s)
| | - Steven H Liang
- Massachusetts General Hospital, Harvard Medical School, Boston, USA.
| | - Michael S Placzek
- Athinoula A. Martinos Center for Biomedical Imaging, MGH, HMS, Charlestown, USA and McLean Hospital, Belmont, USA
| | - Jacob M Hooker
- Athinoula A. Martinos Center for Biomedical Imaging, MGH, HMS, Charlestown, USA
| | | | - Frédéric Dollé
- CEA - Institut d'imagerie biomédicale, Service hospitalier Frédéric Joliot, Université Paris-Saclay, Orsay, France
| | - Alan A Wilson
- Centre for Addiction and Mental Health, Toronto, Canada
| | - Neil Vasdev
- Massachusetts General Hospital, Harvard Medical School, Boston, USA.
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Elevated Monoamine Oxidase-A Distribution Volume in Borderline Personality Disorder Is Associated With Severity Across Mood Symptoms, Suicidality, and Cognition. Biol Psychiatry 2016; 79:117-26. [PMID: 25698585 PMCID: PMC4942262 DOI: 10.1016/j.biopsych.2014.11.024] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 10/31/2014] [Accepted: 11/21/2014] [Indexed: 01/19/2023]
Abstract
BACKGROUND Monoamine oxidase-A (MAO-A) is a treatment target in neurodegenerative illness and mood disorders that increases oxidative stress and predisposition toward apoptosis. Increased MAO-A levels in prefrontal cortex (PFC) and anterior cingulate cortex (ACC) occur in rodent models of depressive behavior and human studies of depressed moods. Extreme dysphoria is common in borderline personality disorder (BPD), especially when severe, and the molecular underpinnings of severe BPD are largely unknown. We hypothesized that MAO-A levels in PFC and ACC would be highest in severe BPD and would correlate with symptom magnitude. METHODS [(11)C] Harmine positron emission tomography measured MAO-A total distribution volume (MAO-A VT), an index of MAO-A density, in severe BPD subjects (n = 14), moderate BPD subjects (n = 14), subjects with a major depressive episode (MDE) only (n = 14), and healthy control subjects (n = 14). All subjects were female. RESULTS Severe BPD was associated with greater PFC and ACC MAO-A VT compared with moderate BPD, MDE, and healthy control subjects (multivariate analysis of variance group effect: F6,102 = 5.6, p < .001). In BPD, PFC and ACC MAO-A VT were positively correlated with mood symptoms (PFC: r = .52, p = .005; ACC: r = .53, p = .004) and suicidality (PFC: r = .40, p = .037; ACC: r = .38, p = .046), while hippocampus MAO-A VT was negatively correlated with verbal memory (r = -.44, p = .023). CONCLUSIONS These results suggest that elevated MAO-A VT is associated with multiple indicators of BPD severity, including BPD symptomatology, mood symptoms, suicidality, and neurocognitive impairment.
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Imaging of monoamine oxidase-A in the human brain with [11C]befloxatone: quantification strategies and correlation with mRNA transcription maps. Nucl Med Commun 2015; 35:1254-61. [PMID: 25185897 DOI: 10.1097/mnm.0000000000000196] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
INTRODUCTION [C]Befloxatone is a highly specific, reversible, and selective radioligand for brain PET imaging of monoamine oxidase-A and can be quantified by a two-tissue compartment model (2TCM) and an arterial input function. The aims of the present study were the following: (a) to assess whether in-vivo protein concentration, as measured by [C]befloxatone total distribution volume (VT), is correlated with post-mortem mRNA expression; (b) to replicate in a population of tobacco smokers the results of a recent study on healthy nonsmokers, which showed that spectral analysis (SA) provides a highly accurate estimation of [C]befloxatone-VT at the voxel level; and (c) to validate the use of an input function that would not require arterial sampling. MATERIALS AND METHODS Healthy male nonsmokers (n=7) and smokers (n=8) were imaged with PET and [C]befloxatone. Binding was quantified at the regional and voxel level with the Logan plot, multilinear analysis (MA1), and SA. VT values were compared with the reference values obtained by 2TCM at the regional level. [C]Befloxatone binding was compared with mRNA transcription maps from the Allen Human Brain Atlas. A less-invasive input function was obtained with a population-based input function (PBIF) scaled with arterialized venous samples. RESULTS mRNA expression was highly correlated with in-vivo 2TCM-VT values both for nonsmokers (R=0.873; P<0.0001) and for smokers (R=0.851; P<0.0001). At the regional level, both Logan and MA1 showed a moderate negative bias (-5 to -10%) compared with the reference VT values. With the exception of a single outlying individual, SA showed little bias and variability (+4.4±3.5%). Although variability was higher than at the regional level, SA provided the most accurate VT estimations at the voxel level: all but one participant had an error of less than 20%. Parametric Logan and MA1 analyses gave highly biased or unusable results. PBIF provided good results in all participants in whom the arterialization of venous blood was successful (all errors of about 10% or less). CONCLUSION [C]Befloxatone binding is strongly correlated with the values of mRNA transcription measured in post-mortem brains. At the voxel level, SA is the best available choice for [C]befloxatone quantification, although a higher variability must be expected. When an arterial input function is not technically feasible, a PBIF scaled with arterialized venous samples may provide an acceptable alternative, provided an optimal arterialization can be achieved.
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Fowler JS, Logan J, Shumay E, Alia-Klein N, Wang GJ, Volkow ND. Monoamine oxidase: radiotracer chemistry and human studies. J Labelled Comp Radiopharm 2015; 58:51-64. [PMID: 25678277 DOI: 10.1002/jlcr.3247] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Accepted: 10/31/2014] [Indexed: 11/09/2022]
Abstract
Monoamine oxidase (MAO) oxidizes amines from both endogenous and exogenous sources thereby regulating the concentration of neurotransmitter amines such as serotonin, norepinephrine, and dopamine as well as many xenobiotics. MAO inhibitor drugs are used in the treatment of Parkinson's disease and in depression stimulating the development of radiotracer tools to probe the role of MAO in normal human biology and in disease. Over the past 30 years since the first radiotracers were developed and the first positron emission tomography (PET) images of MAO in humans were carried out, PET studies of brain MAO in healthy volunteers and in patients have identified different variables that have contributed to different MAO levels in brain and in peripheral organs. MAO radiotracers and PET have also been used to study the current and developing MAO inhibitor drugs including the selection of doses for clinical trials. In this article, we describe the following: (1) the development of MAO radiotracers; (2) human studies including the relationship of brain MAO levels to genotype, personality, neurological, and psychiatric disorders; and (3) examples of the use of MAO radiotracers in drug research and development. We will conclude with outstanding needs to improve the radiotracers that are currently used and possible new applications.
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Affiliation(s)
- Joanna S Fowler
- Biological, Environmental and Climate Sciences Department, Brookhaven National Laboratory, Upton, NY, USA
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Monoamine oxidase A and B substrates: probing the pathway for drug development. Future Med Chem 2014; 6:697-717. [DOI: 10.4155/fmc.14.23] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Drug-discovery and -development efforts focused on the MAOs have increased at an accelerated rate over the past decade. Since the first crystal structure of human MAO-B was solved in 2002, over 40 additional structures have been reported and have helped define new, or confirm speculative, binding modes of inhibitors. The detailed mechanism of the MAO-catalyzed oxidation of amine substrates has not been fully elucidated, but its significance is central in the development of new mechanism-based inactivators. Novel fungal MAO-N variants derived from directed evolution strategies are enabling the production of new chiral amine products. Robust assays have been established for measuring MAO status in tissue and cells, while improved MAO radioligands are being deployed for PET imaging studies. This review will attempt to highlight the more recent and salient aspects of MAO research in drug discovery and development, with emphasis on substrates 'probing the pathway'.
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Zanotti-Fregonara P, Leroy C, Roumenov D, Trichard C, Martinot JL, Bottlaender M. Kinetic analysis of [11C]befloxatone in the human brain, a selective radioligand to image monoamine oxidase A. EJNMMI Res 2013; 3:78. [PMID: 24274579 PMCID: PMC4176482 DOI: 10.1186/2191-219x-3-78] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Accepted: 10/21/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND [11C]Befloxatone measures the density of the enzyme monoamine oxidase A (MAO-A) in the brain. MAO-A is responsible for the degradation of different neurotransmitters and is implicated in several neurologic and psychiatric illnesses. This study sought to estimate the distribution volume (VT) values of [11C]befloxatone in humans using an arterial input function. METHODS Seven healthy volunteers were imaged with positron emission tomography (PET) after [11C]befloxatone injection. Kinetic analysis was performed using an arterial input function in association with compartmental modeling and with the Logan plot, multilinear analysis (MA1), and standard spectral analysis (SA) at both the regional and voxel level. Arterialized venous samples were drawn as an alternative and less invasive input function. RESULTS An unconstrained two-compartment model reliably quantified VT values in large brain regions. A constrained model did not significantly improve VT identifiability. Similar VT results were obtained using SA; however, the Logan plot and MA1 slightly underestimated VT values (about -10%). At the voxel level, SA showed a very small bias (+2%) compared to compartmental modeling, Logan severely underestimated VT values, and voxel-wise images obtained with MA1 were too noisy to be reliably quantified. Arterialized venous blood samples did not provide a satisfactory alternative input function as the Logan-VT regional values were not comparable to those obtained with arterial sampling in all subjects. CONCLUSIONS Binding of [11C]befloxatone to MAO-A can be quantified using an arterial input function and a two-compartment model or, in parametric images, with SA.
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Sacher J, Houle S, Parkes J, Rusjan P, Sagrati S, Wilson AA, Meyer JH. Monoamine oxidase A inhibitor occupancy during treatment of major depressive episodes with moclobemide or St. John's wort: an [11C]-harmine PET study. J Psychiatry Neurosci 2011; 36:375-82. [PMID: 21463543 PMCID: PMC3201991 DOI: 10.1503/jpn.100117] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Monoamine oxidase A (MAO-A) inhibitor antidepressants raise levels of multiple monoamines, whereas the selective serotonin reuptake inhibitors (SSRIs) only raise extracellular serotonin. Despite this advantage of MAO-A inhibitors, there is much less frequent development of MAO inhibitors compared with SSRIs. We sought to measure brain MAO-A occupancy after 6 weeks of treatment in depressed patients with a clinically effective dose of a selective MAO-A inhibitor and measure MAO-A occupancy after repeated administration of St. John's wort, an herb purported to have MAO-A inhibitor properties. METHODS Participants underwent 2 [(11)C]-harmine positron emission tomography scans. Healthy controls completed a test-retest condition, and depressed patients were scanned before and after repeated administration of moclobemide or St. John's wort for 6 weeks at the assigned dose. We measured MAO-A VT, an index of MAO-A density, in the prefrontal, anterior cingulate and anterior temporal cortices, putamen, thalamus, midbrain and hippocampus. RESULTS We included 23 participants (10 controls and 13 patients with major depressive disorder [MDD]) in our study. Monoamine oxidase A VT decreased significantly throughout all regions after moclobemide treatment in patients with MDD compared with controls (repeated-measures analysis of variance, F1,15 = 71.08-130.06, p < 0.001 for all regions, mean occupancy 74% [standard deviation 6%]). Treatment with St. John's wort did not significantly alter MAO-A VT. LIMITATIONS The occupancy estimates are limited by the sample size of each treatment group; hence, our estimate for the overall moclobemide occupancy of 74% has a 95% confidence interval of 70%-78%, and we can estimate with 95% certainty that the occupancy of St. John's wort is less than 5%. CONCLUSION For new MAO-A inhibitors, about 74% occupancy at steady-state dosing is desirable. Consistent with this, St. John's wort should not be classified as an MAO-A inhibitor. The magnitude of MAO-A blockade during moclobemide treatment exceeds the elevation of MAO-A binding during illness by at least 30%, suggesting that the treatment effect should exceed the disease effect when designing selective antidepressants for this target.
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Affiliation(s)
| | | | | | | | | | | | - Jeffrey H. Meyer
- Correspondence to: Dr. J.H. Meyer, College Street Site, Centre for Addiction and Mental Health, PET Centre, 250 College St., Toronto ON M5T 1R8;
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Saulin A, Savli M, Lanzenberger R. Serotonin and molecular neuroimaging in humans using PET. Amino Acids 2011; 42:2039-57. [PMID: 21947614 DOI: 10.1007/s00726-011-1078-9] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Accepted: 09/05/2011] [Indexed: 02/07/2023]
Abstract
The serotonergic system is one of the most important modulatory neurotransmitter systems in the human brain. It plays a central role in major physiological processes and is implicated in a number of psychiatric disorders. Along with the dopaminergic system, it is also one of the phylogenetically oldest human neurotransmitter systems and one of the most diverse, with 14 different receptors identified up to this day, many of whose function remains to be understood. The system's functioning is even more diverse than the number of its receptors, since each is implicated in a number of different processes. This review aims at illustrating the distribution and summarizing the main functions of the serotonin (5-hydroxytryptamin, 5-HT) receptors as well as the serotonin transporter (SERT, 5-HTT), the vesicular monoamine transporter 2, monoamine oxidase type A and 5-HT synthesis in the human brain. Recent advances in in vivo quantification of these different receptors and enzymes that are part of the serotonergic system using positron emission tomography are described.
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Affiliation(s)
- Anne Saulin
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria
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In vivo quantification of monoamine oxidase A in baboon brain: a PET study using [(11)C]befloxatone and the multi-injection approach. J Cereb Blood Flow Metab 2010; 30:792-800. [PMID: 19920845 PMCID: PMC2949159 DOI: 10.1038/jcbfm.2009.242] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
[(11)C]befloxatone is a high-affinity, reversible, and selective radioligand for the in vivo visualization of the monoamine oxidase A (MAO-A) binding sites using positron emission tomography (PET). The multi-injection approach was used to study in baboons the interactions between the MAO-A binding sites and [(11)C]befloxatone. The model included four compartments and seven parameters. The arterial plasma concentration, corrected for metabolites, was used as input function. The experimental protocol-three injections of labeled and/or unlabeled befloxatone-allowed the evaluation of all the model parameters from a single PET experiment. In particular, the brain regional concentrations of the MAO-A binding sites (B'(max)) and the apparent in vivo befloxatone affinity (K(d)) were estimated in vivo for the first time. A high binding site density was found in almost all the brain structures (170+/-39 and 194+/-26 pmol/mL in the frontal cortex and striata, respectively, n=5). The cerebellum presented the lowest binding site density (66+/-13 pmol/mL). Apparent affinity was found to be similar in all structures (K(d)V(R)=6.4+/-1.5 nmol/L). This study is the first PET-based estimation of the B(max) of an enzyme.
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Saba W, Valette H, Peyronneau MA, Bramoullé Y, Coulon C, Curet O, George P, Dollé F, Bottlaender M. [11C]SL25.1188, a new reversible radioligand to study the monoamine oxidase type B with PET: Preclinical characterisation in nonhuman primate. Synapse 2010; 64:61-9. [DOI: 10.1002/syn.20703] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Cerebral monoamine oxidase A inhibition in tobacco smokers confirmed with PET and [11C]befloxatone. J Clin Psychopharmacol 2009; 29:86-8. [PMID: 19142115 DOI: 10.1097/jcp.0b013e31819e98f] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The inhibition of cerebral monoamine oxidases (MAOs) by cigarette smoke components could participate to the tobacco addiction. However, the actual extent of this inhibition in vivo in smokers is still poorly known. We investigated cerebral MAO-A availability in 7 tobacco-dependent subjects and 6 healthy nonsmokers, using positron emission tomography (PET) and the MAO-A selective radioligand [C]befloxatone. In comparison to nonsmokers, smokers showed a significant overall reduction of [C]befloxatone binding potential (BP) in cortical areas (average reduction, -60%) and a similar trend in caudate and thalamus (-40%). Our findings confirm a widespread inhibition of cerebral MAO-A in smokers. This mechanism may contribute to tobacco addiction and for a possible mood-modulating effect of tobacco.
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Abstract
The recent increase in radioligands available for neuroimaging major depressive disorder has led to advancements in our understanding of the pathophysiology of this illness and improved antidepressant development. Major depressive disorder can be defined as an illness of recurrent major depressive episodes of persistently low mood, dysregulated sleep, appetite and weight, anhedonia, cognitive impairment, and suicidality. The main target sites investigated with radioligand neuroimaging include receptor sites that regulate in response to lowered monoamine levels, targets related to removal of monoamines, uptake of ligands related to regional brain function, and target sites of antidepressants.
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Affiliation(s)
- Jeffrey H Meyer
- Department of Psychiatry, University of Toronto, Toronto, Canada.
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Jensen SB, Di Santo R, Olsen AK, Pedersen K, Costi R, Cirilli R, Cumming P. Synthesis and Cerebral Uptake of 1-(1-[11C]Methyl-1H-pyrrol-2-yl)-2-phenyl-2-(1-pyrrolidinyl)ethanone, a Novel Tracer for Positron Emission Tomography Studies of Monoamine Oxidase Type A. J Med Chem 2008; 51:1617-22. [DOI: 10.1021/jm701378e] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Svend Borup Jensen
- PET Centre, Aarhus University Hospital, Nørrebrogade 44, 8000 Århus C, Denmark, Istituto Pasteur—Fondazione Cenci Bolognetti, Dipartimento di Studi Farmaceutici, Università di Roma “La Sapienza”, P. le A. Moro 5, I-00185 Roma, Italy, and Dipartimento del Farmaco, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Roma, Italy
| | - Roberto Di Santo
- PET Centre, Aarhus University Hospital, Nørrebrogade 44, 8000 Århus C, Denmark, Istituto Pasteur—Fondazione Cenci Bolognetti, Dipartimento di Studi Farmaceutici, Università di Roma “La Sapienza”, P. le A. Moro 5, I-00185 Roma, Italy, and Dipartimento del Farmaco, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Roma, Italy
| | - Aage Kristian Olsen
- PET Centre, Aarhus University Hospital, Nørrebrogade 44, 8000 Århus C, Denmark, Istituto Pasteur—Fondazione Cenci Bolognetti, Dipartimento di Studi Farmaceutici, Università di Roma “La Sapienza”, P. le A. Moro 5, I-00185 Roma, Italy, and Dipartimento del Farmaco, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Roma, Italy
| | - Kasper Pedersen
- PET Centre, Aarhus University Hospital, Nørrebrogade 44, 8000 Århus C, Denmark, Istituto Pasteur—Fondazione Cenci Bolognetti, Dipartimento di Studi Farmaceutici, Università di Roma “La Sapienza”, P. le A. Moro 5, I-00185 Roma, Italy, and Dipartimento del Farmaco, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Roma, Italy
| | - Roberta Costi
- PET Centre, Aarhus University Hospital, Nørrebrogade 44, 8000 Århus C, Denmark, Istituto Pasteur—Fondazione Cenci Bolognetti, Dipartimento di Studi Farmaceutici, Università di Roma “La Sapienza”, P. le A. Moro 5, I-00185 Roma, Italy, and Dipartimento del Farmaco, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Roma, Italy
| | - Roberto Cirilli
- PET Centre, Aarhus University Hospital, Nørrebrogade 44, 8000 Århus C, Denmark, Istituto Pasteur—Fondazione Cenci Bolognetti, Dipartimento di Studi Farmaceutici, Università di Roma “La Sapienza”, P. le A. Moro 5, I-00185 Roma, Italy, and Dipartimento del Farmaco, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Roma, Italy
| | - Paul Cumming
- PET Centre, Aarhus University Hospital, Nørrebrogade 44, 8000 Århus C, Denmark, Istituto Pasteur—Fondazione Cenci Bolognetti, Dipartimento di Studi Farmaceutici, Università di Roma “La Sapienza”, P. le A. Moro 5, I-00185 Roma, Italy, and Dipartimento del Farmaco, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Roma, Italy
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Bramoullé Y, Puech F, Saba W, Valette H, Bottlaender M, George P, Dollé F. Radiosynthesis of (S)-5-methoxymethyl-3-[6-(4,4,4-trifluorobutoxy)benzo[d]isoxazol-3-yl] oxazolidin-2-[11C]one ([11C]SL25.1188), a novel radioligand for imaging monoamine oxidase-B with PET. J Labelled Comp Radiopharm 2008. [DOI: 10.1002/jlcr.1492] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Roeda D, Kuhnast B, Hammadi A, Dollé F. The Service Hospitalier Frédéric Joliot – contributions to PET chemistry over the years. J Labelled Comp Radiopharm 2007. [DOI: 10.1002/jlcr.1420] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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Ginovart N, Meyer JH, Boovariwala A, Hussey D, Rabiner EA, Houle S, Wilson AA. Positron emission tomography quantification of [11C]-harmine binding to monoamine oxidase-A in the human brain. J Cereb Blood Flow Metab 2006; 26:330-44. [PMID: 16079787 DOI: 10.1038/sj.jcbfm.9600197] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
This article describes the kinetic modeling of [(11)C]-harmine binding to monoamine oxidase A (MAO-A) binding sites in the human brain using positron emission tomography (PET). Positron emission tomography studies were performed in healthy volunteers at placebo conditions and after treatment with clinical doses of moclobemide. In either condition, a two-tissue compartment model (2CM) provided better fits to the data than a one-tissue model. Estimates of k(3)/k(4) values from an unconstrained 2CM were highly variable. In contrast, estimates of the specifically bound radioligand distribution volume (DV(B)) from an unconstrained 2CM were exceptionally stable, correlated well with the known distribution of MAO-A in the brain (cerebellum <frontal cortex approximately putamen <temporal cortex approximately cingulate <thalamus) and thus provided reliable indices of MAO-A density. Total distribution volume (DV) values were also highly stable and not different from those estimated with the Logan approach. Fixing the DV of free and nonspecifically bound radiotracer (DV(F + NS)) or coupling DV(F + NS) between brain regions enabled more stable estimates of k(3)/k(4) as compared with an unconstrained 2CM. Moclobemide treatment leads to a 64% to 79% MAO-A blockade across brain regions, a result that supports the specificity of [(11)C]-harmine binding to MAO-A. The stability and reliability of DV(B) values obtained from an unconstrained 2CM, together with the computational simplicity associated with this method, support the use of DV(B) as an appropriate outcome measure for [(11)C]-harmine. These results indicate the suitability of using [(11)C]-harmine for quantitative evaluation of MAO-A densities using PET and should enable further studies of potential MAO-A dysregulation in several psychiatric and neurologic illnesses.
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Affiliation(s)
- Nathalie Ginovart
- PET Centre, Centre for Addiction and Mental Health, Toronto, Canada.
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Youdim MBH, Bakhle YS. Monoamine oxidase: isoforms and inhibitors in Parkinson's disease and depressive illness. Br J Pharmacol 2006; 147 Suppl 1:S287-96. [PMID: 16402116 PMCID: PMC1760741 DOI: 10.1038/sj.bjp.0706464] [Citation(s) in RCA: 443] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
A few years after the foundation of the British Pharmacological Society, monoamine oxidase (MAO) was recognized as an enzyme of crucial interest to pharmacologists because it catalyzed the major inactivation pathway for the catecholamine neurotransmitters, noradrenaline, adrenaline and dopamine (and, later, 5-hydroxytryptamine, as well). Within the next decade, the therapeutic value of inhibitors of MAO in the treatment of depressive illness was established. Although this first clinical use exposed serious side effects, pharmacological interest in, and investigation of, MAO continued, resulting in the characterization of two isoforms, MAO-A and -B, and isoform-selective inhibitors. Selective inhibitors of MAO-B have found a therapeutic role in the treatment of Parkinson's disease and further developments have provided reversible inhibitors of MAO-A, which offer antidepressant activity without the serious side effects of the earlier inhibitors. Clinical observation and subsequent pharmacological analysis have also generated the concept of neuroprotection, reflecting the possibility of slowing, halting and maybe reversing, neurodegeneration in Parkinson's or Alzheimer's diseases. Increased levels of oxidative stress in the brain may be critical for the initiation and progress of neurodegeneration and selective inhibition of brain MAO could contribute importantly to lowering such stress. There are complex interactions between free iron levels in brain and MAO, which may have practical outcomes for depressive disorders. These aspects of MAO and its inhibition and some indication of how this important area of pharmacology and therapeutics might develop in the future are summarized in this review.
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Affiliation(s)
- Moussa B H Youdim
- Department of Pharmacology and Technion-Bruce Rappaport Faculty of Medicine, Eve Topf and NPF Centers of Excellence for Neurodegenerative Diseases Research and Teaching, Haifa, Israel.
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Valette H, Bottlaender M, Dollé F, Coulon C, Ottaviani M, Syrota A. Acute inhibition of cardiac monoamine oxidase A after tobacco smoke inhalation: validation study of [11C]befloxatone in rats followed by a positron emission tomography application in baboons. J Pharmacol Exp Ther 2005; 314:431-6. [PMID: 15833896 DOI: 10.1124/jpet.105.085704] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The in vivo characteristics of [11C]befloxatone were assessed in myocardium of rats and monkeys. A complete multicompartmental model was developed to quantify monkey cardiac monoamine oxidase A (MAO-A) binding sites using positron emission tomography (PET) and was applied to assess the acute effects of inhalation of tobacco smoke. Unknown compounds contained in tobacco smoke inhibit brain MAO. In vitro, befloxatone inhibits selectively, competitively, and reversibly MAO-A in human tissues. [11C]Befloxatone (1.85 MBq) was i.v. injected into rats. Animals were sacrificed, dissected, and samples were assessed for radioactivity. Another group of rats was pretreated with clorgyline (10 mg/kg i.v.). Monkeys were injected with [11C]befloxatone (222-370 MBq), and the chest was imaged with PET for 2 h. Presaturation and displacement experiments were performed using unlabeled befloxatone. For quantification of myocardial binding sites (Bmax), [11C]befloxatone was first injected as a tracer dose (2.7-9.3 nmol) and 20 min later injected as a mixture of labeled and unlabeled befloxatone (labeled, 10.3-41.9 nmol; unlabeled, 407-765 nmol). In rodents, cardiac uptake was high (3.39 +/- 0.5% injected dose/g tissue) and strongly inhibited (80%) by clorgyline. In monkeys, administration of unlabeled befloxatone displaced 85% of cardiac radioactivity. Bmax was found to be 208 +/- 13 pmol ml(-1) tissue. Inhalation of tobacco smoke decreased Bmax: 150 +/- 6.2 pmol ml(-1), whereas nicotine did not. [11C]Befloxatone allows a good visualization of the heart. Cardiac MAO-A Bmax was quantified and a clear effect of acute inhalation of tobacco smoke was evidenced. Therefore, a single cigarette can interfere with the cardiac turnover of catecholamines.
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Affiliation(s)
- Héric Valette
- Service Hospitalier Frédéric Joliot, DSV/DRM-CEA, French Atomic Agency, F-91406 Orsay, France.
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Dollé F, Bramoullé Y, Hinnen F, Demphel S, George P, Bottlaender M. Efficient synthesis of [11C]befloxatone, a selective radioligand for thein vivoimaging of MAO-A density using PET. J Labelled Comp Radiopharm 2003. [DOI: 10.1002/jlcr.718] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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