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Zirbesegger K, Reyes L, Paolino A, Dapueto R, Arredondo F, Gambini JP, Savio E, Porcal W. Molecular Imaging of Monoamine Oxidase A Expression in Highly Aggressive Prostate Cancer: Synthesis and Preclinical Evaluation of Positron Emission Tomography Tracers. ACS Pharmacol Transl Sci 2023; 6:1734-1744. [PMID: 37982127 PMCID: PMC10653014 DOI: 10.1021/acsptsci.3c00175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 10/05/2023] [Accepted: 10/10/2023] [Indexed: 11/21/2023]
Abstract
The role of monoamine oxidase A (MAO-A) in the aggressiveness of prostate cancer (PCa) has been established in recent years. The molecular imaging of MAO-A expression could offer a noninvasive tool for the visualization and quantification of highly aggressive PCa. This study reports the synthesis and preclinical evaluation of 11C- and 18F-labeled MAO-A inhibitors as positron emission tomography (PET) tracers for proof-of-concept studies in animal models of PCa. Good manufacturing practice production and quality control of these radiotracers using an automated platform was achieved. PET imaging was performed in an LNCaP tumor model with high MAO-A expression. The tumor-to-muscle (T/M) uptake ratio of [11C]harmine (4.5 ± 0.5) was significantly higher than that for 2-[18F]fluoroethyl-harmol (2.3 ± 0.7) and [11C]clorgyline (2.0 ± 0.1). A comparable ex vivo biodistribution pattern in all radiotracers was observed. Furthermore, the tumor uptake of [11C]harmine showed a dramatic reduction (T/M = 1) in a PC3 tumor model with limited MAO-A expression, and radioactivity uptake in LNCaP tumors was blocked in the presence of nonradioactive harmine. Our findings suggest that [11C]harmine may serve as an attractive PET probe for the visualization of MAO-A expression in highly aggressive PCa. These radiotracers have the potential for clinical translation and may aid in the development of personalized therapeutic strategies for PCa patients.
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Affiliation(s)
- Kevin Zirbesegger
- Centro Uruguayo de Imagenología Molecular (CUDIM), Ricaldoni 2010, 11600 Montevideo, Uruguay
- Programa de Posgrado, Facultad de Química, Universidad de la República, Av. General Flores 2124, 11800 Montevideo, Uruguay
| | - Laura Reyes
- Centro Uruguayo de Imagenología Molecular (CUDIM), Ricaldoni 2010, 11600 Montevideo, Uruguay
| | - Andrea Paolino
- Centro Uruguayo de Imagenología Molecular (CUDIM), Ricaldoni 2010, 11600 Montevideo, Uruguay
| | - Rosina Dapueto
- Centro Uruguayo de Imagenología Molecular (CUDIM), Ricaldoni 2010, 11600 Montevideo, Uruguay
| | - Florencia Arredondo
- Centro Uruguayo de Imagenología Molecular (CUDIM), Ricaldoni 2010, 11600 Montevideo, Uruguay
| | - Juan P Gambini
- Centro Uruguayo de Imagenología Molecular (CUDIM), Ricaldoni 2010, 11600 Montevideo, Uruguay
| | - Eduardo Savio
- Centro Uruguayo de Imagenología Molecular (CUDIM), Ricaldoni 2010, 11600 Montevideo, Uruguay
| | - Williams Porcal
- Departamento de Química Orgánica, Facultad de Química, Universidad de la República, Av. General Flores 2124, 11800 Montevideo, Uruguay
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Thomsen MB, Landau AM, Bender D, Cumming P. Autoradiographic characterization of [ 18 F]PSMA-1007 binding in rat brain. Synapse 2023; 77:e22280. [PMID: 37400743 DOI: 10.1002/syn.22280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 06/05/2023] [Accepted: 06/20/2023] [Indexed: 07/05/2023]
Abstract
Carboxypeptidase II (CBPII) in brain metabolizes the neuroactive substance N-acetyl-L-aspartyl-L-glutamate (NAGG) to yield the elements of glutamate and N-acetyl-aspartate (NAA). In peripheral organs, CBPII is known as prostrate specific membrane antigen (PSMA), which presents an important target for nuclear medicine imaging in prostate cancer. Available PSMA ligands for PET imaging do not cross the blood-brain barrier, and there is scant knowledge of the neurobiology of CBPII, despite its implication in the regulation of glutamatergic neurotransmission. In this study we used the clinical PET tracer [18 F]-PSMA-1007 ([18 F]PSMA) for an autoradiographic characterization of CGPII in rat brain. Ligand binding and displacement curves indicated a single site in brain, with KD of about 0.5 nM, and Bmax ranging from 9 nM in cortex to 19 nM in white matter (corpus callosum and fimbria) and 24 nM in hypothalamus. The binding properties of [18 F]PSMA in vitro should enable its use for autoradiographic investigations of CBPII expression in animal models of human neuropsychiatric conditions.
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Affiliation(s)
- Majken B Thomsen
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
- Department of Nuclear Medicine and PET, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Anne M Landau
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
- Department of Nuclear Medicine and PET, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Dirk Bender
- Department of Nuclear Medicine and PET, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Paul Cumming
- Department of Nuclear Medicine, Bern University Hospital, Bern, Switzerland
- School of Psychology and Counselling, Queensland University of Technology, Brisbane, Australia
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Egger K, Gudmundsen F, Jessen NS, Baun C, Poetzsch SN, Shalgunov V, Herth MM, Quednow BB, Martin-Soelch C, Dornbierer D, Scheidegger M, Cumming P, Palner M. A pilot study of cerebral metabolism and serotonin 5-HT 2A receptor occupancy in rats treated with the psychedelic tryptamine DMT in conjunction with the MAO inhibitor harmine. Front Pharmacol 2023; 14:1140656. [PMID: 37841918 PMCID: PMC10568461 DOI: 10.3389/fphar.2023.1140656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Accepted: 09/19/2023] [Indexed: 10/17/2023] Open
Abstract
Rationale: The psychedelic effects of the traditional Amazonian botanical decoction known as ayahuasca are often attributed to agonism at brain serotonin 5-HT2A receptors by N,N-dimethyltryptamine (DMT). To reduce first pass metabolism of oral DMT, ayahuasca preparations additionally contain reversible monoamine oxidase A (MAO-A) inhibitors, namely β-carboline alkaloids such as harmine. However, there is lacking biochemical evidence to substantiate this pharmacokinetic potentiation of DMT in brain via systemic MAO-A inhibition. Objectives: We measured the pharmacokinetic profile of harmine and/or DMT in rat brain, and tested for pharmacodynamic effects on brain glucose metabolism and DMT occupancy at brain serotonin 5-HT2A receptors. Methods: We first measured brain concentrations of harmine and DMT after treatment with harmine and/or DMT at low sub-cutaneous doses (1 mg/kg each) or harmine plus DMT at moderate doses (3 mg/kg each). In the same groups of rats, we also measured ex vivo the effects of these treatments on the availability of serotonin 5-HT2A receptors in frontal cortex. Finally, we explored effects of DMT and/or harmine (1 mg/kg each) on brain glucose metabolism with [18F]FDG-PET. Results: Results confirmed that co-administration of harmine inhibited the formation of the DMT metabolite indole-3-acetic acid (3-IAA) in brain, while correspondingly increasing the cerebral availability of DMT. However, we were unable to detect any significant occupancy by DMT at 5-HT2A receptors measured ex vivo, despite brain DMT concentrations as high as 11.3 µM. We did not observe significant effects of low dose DMT and/or harmine on cerebral [18F]FDG-PET uptake. Conclusion: These preliminary results call for further experiments to establish the dose-dependent effects of harmine/DMT on serotonin receptor occupancy and cerebral metabolism.
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Affiliation(s)
- Klemens Egger
- Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric University Hospital Zurich, University of Zurich, Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich and Swiss Federal Institute of Technology Zurich, Zurich, Switzerland
- Department of Nuclear Medicine, Bern University Hospital, Bern, Switzerland
| | - Frederik Gudmundsen
- Department of Clinical Research, University of Southern Denmark, Odense, Denmark
- Department of Nuclear Medicine, Odense University Hospital, Odense, Denmark
| | - Naja Støckel Jessen
- Department of Clinical Research, University of Southern Denmark, Odense, Denmark
- Department of Nuclear Medicine, Odense University Hospital, Odense, Denmark
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Christina Baun
- Department of Clinical Research, University of Southern Denmark, Odense, Denmark
- Department of Nuclear Medicine, Odense University Hospital, Odense, Denmark
| | - Sandra N. Poetzsch
- Department of Forensic Pharmacology and Toxicology, Zurich Institute of Forensic Medicine, University of Zurich, Zurich, Switzerland
| | - Vladimir Shalgunov
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
- Department of Clinical Physiology, Nuclear Medicine and PET, Copenhagen University Hospital, Copenhagen, Denmark
| | - Matthias M. Herth
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
- Department of Clinical Physiology, Nuclear Medicine and PET, Copenhagen University Hospital, Copenhagen, Denmark
| | - Boris B. Quednow
- Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric University Hospital Zurich, University of Zurich, Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich and Swiss Federal Institute of Technology Zurich, Zurich, Switzerland
| | | | - Dario Dornbierer
- Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Milan Scheidegger
- Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric University Hospital Zurich, University of Zurich, Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich and Swiss Federal Institute of Technology Zurich, Zurich, Switzerland
| | - Paul Cumming
- Department of Nuclear Medicine, Bern University Hospital, Bern, Switzerland
- School of Psychology and Counselling, Queensland University of Technology, Brisbane, Australia
| | - Mikael Palner
- Department of Clinical Research, University of Southern Denmark, Odense, Denmark
- Department of Nuclear Medicine, Odense University Hospital, Odense, Denmark
- Neurobiology Research Unit, Copenhagen University Hospital, Copenhagen, Denmark
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Syed AU, Liang C, Patel KK, Mondal R, Kamalia VM, Moran TR, Ahmed ST, Mukherjee J. Comparison of Monoamine Oxidase-A, Aβ Plaques, Tau, and Translocator Protein Levels in Postmortem Human Alzheimer's Disease Brain. Int J Mol Sci 2023; 24:10808. [PMID: 37445985 PMCID: PMC10341404 DOI: 10.3390/ijms241310808] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2023] [Revised: 06/19/2023] [Accepted: 06/26/2023] [Indexed: 07/15/2023] Open
Abstract
Increased monoamine oxidase-A (MAO-A) activity in Alzheimer's disease (AD) may be detrimental to the point of neurodegeneration. To assess MAO-A activity in AD, we compared four biomarkers, Aβ plaques, tau, translocator protein (TSPO), and MAO-A in postmortem AD. Radiotracers were [18F]FAZIN3 for MAO-A, [18F]flotaza and [125I]IBETA for Aβ plaques, [124/125I]IPPI for tau, and [18F]FEPPA for TSPO imaging. Brain sections of the anterior cingulate (AC; gray matter GM) and corpus callosum (CC; white matter WM) from cognitively normal control (CN, n = 6) and AD (n = 6) subjects were imaged using autoradiography and immunostaining. Using competition with clorgyline and (R)-deprenyl, the binding of [18F]FAZIN3 was confirmed to be selective to MAO-A levels in the AD brain sections. Increases in MAO-A, Aβ plaque, tau, and TSPO activity were found in the AD brains compared to the control brains. The [18F]FAZIN3 ratio in AD GM versus CN GM was 2.80, suggesting a 180% increase in MAO-A activity. Using GM-to-WM ratios of AD versus CN, a >50% increase in MAO-A activity was observed (AD/CN = 1.58). Linear positive correlations of [18F]FAZIN3 with [18F]flotaza, [125I]IBETA, and [125I]IPPI were measured and suggested an increase in MAO-A activity with increases in Aβ plaques and tau activity. Our results support the finding that MAO-A activity is elevated in the anterior cingulate cortex in AD and thus may provide a new biomarker for AD in this brain region.
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Affiliation(s)
| | | | | | | | | | | | | | - Jogeshwar Mukherjee
- Preclinical Imaging, Department of Radiological Sciences, University of California-Irvine, Irvine, CA 92697, USA
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Mukherjee J, Ladwa RM, Liang C, Syed AU. Elevated Monoamine Oxidase-A in Anterior Cingulate of Post-Mortem Human Parkinson's Disease: A Potential Surrogate Biomarker for Lewy Bodies? Cells 2022; 11:cells11244000. [PMID: 36552764 PMCID: PMC9777299 DOI: 10.3390/cells11244000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 11/27/2022] [Accepted: 12/08/2022] [Indexed: 12/14/2022] Open
Abstract
Lewy bodies (LB) play a neuropathological role in Parkinson's disease (PD). Our goal was to evaluate LB using anti-ubiquitin immunohistochemistry (UIHC) and find correlations with monoamine oxidase-A (MAO-A) using imaging agent, [18F]FAZIN3. Human post-mortem anterior cingulate (AC) and corpus callosum (CC) from control subjects (CN), n = 6; age 81-90 LB = 0 and PD, n = 6, age 77-89, LB = III-IV were sectioned (10 μm slices). Brain slices were immunostained with anti-ubiquitin for LB (UIHC) and analyzed using QuPath for percent anti-ubiquitin per unit area (μm2). Adjacent brain slices were incubated with [18F]FAZIN3 and cortical layers I-III, IV-VI and CC (white matter) regions were quantified for the binding of [18F]FAZIN3. UIHC was correlated with [18F]FAZIN3 binding. All PD brains were positively UIHC stained and confirmed presence of LB. Outer cortical layers (I-III) of PD AC had 21% UIHC while inner layers (IV-VI) had >75% UIHC. In the CN brains LB were absent (<1% UIHC). Increased [18F]FAZIN3 binding to MAO-A in AC was observed in all PD subjects. [18F]FAZIN3 ratio in PD was AC/CC = 3.57 while in CN subjects it was AC/CC = 2.24. Increases in UIHC μm2 correlated with [18F]FAZIN3 binding to MAO-A in DLU/mm2. Increased [18F]FAZIN3 binding to MAO-A in PD is a potential novel "hot spot" PET imaging approach.
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Berlowitz I, Egger K, Cumming P. Monoamine Oxidase Inhibition by Plant-Derived β-Carbolines; Implications for the Psychopharmacology of Tobacco and Ayahuasca. Front Pharmacol 2022; 13:886408. [PMID: 35600851 PMCID: PMC9121195 DOI: 10.3389/fphar.2022.886408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 04/07/2022] [Indexed: 11/13/2022] Open
Abstract
The monoamine oxidases (MAOs) are flavin-containing amine oxidoreductases responsible for metabolism of many biogenic amine molecules in the brain and peripheral tissues. Whereas serotonin is the preferred substrate of MAO-A, phenylethylamine is metabolized by MAO-B, and dopamine and tyramine are nearly ambivalent with respect to the two isozymes. β-Carboline alkaloids such as harmine, harman(e), and norharman(e) are MAO inhibitors present in many plant materials, including foodstuffs, medicinal plants, and intoxicants, notably in tobacco (Nicotiana spp.) and in Banisteriopsis caapi, a vine used in the Amazonian ayahuasca brew. The β-carbolines present in B. caapi may have effects on neurogenesis and intrinsic antidepressant properties, in addition to potentiating the bioavailability of the hallucinogen N,N-dimethyltryptamine (DMT), which is often present in admixture plants of ayahuasca such as Psychotria viridis. Tobacco also contains physiologically relevant concentrations of β-carbolines, which potentially contribute to its psychopharmacology. However, in both cases, the threshold of MAO inhibition sufficient to interact with biogenic amine neurotransmission remains to be established. An important class of antidepressant medications provoke a complete and irreversible inhibition of MAO-A/B, and such complete inhibition is almost unattainable with reversible and competitive inhibitors such as β-carbolines. However, the preclinical and clinical observations with synthetic MAO inhibitors present a background for obtaining a better understanding of the polypharmacologies of tobacco and ayahuasca. Furthermore, MAO inhibitors of diverse structures are present in a wide variety of medicinal plants, but their pharmacological relevance in many instances remains to be established.
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Affiliation(s)
- Ilana Berlowitz
- Department of Nuclear Medicine, Inselspital Bern University Hospital, University of Bern, Bern, Switzerland
- *Correspondence: Ilana Berlowitz,
| | - Klemens Egger
- Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Paul Cumming
- Department of Nuclear Medicine, Inselspital Bern University Hospital, University of Bern, Bern, Switzerland
- School of Psychology and Counselling, Queensland University of Technology, Brisbane, QLD, Australia
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Patkar OL, Mohamed AZ, Narayanan A, Mardon K, Cowin G, Bhalla R, Stimson DHR, Kassiou M, Beecher K, Belmer A, Alvarez Cooper I, Morgan M, Hume DA, Irvine KM, Bartlett SE, Nasrallah F, Cumming P. A binge high sucrose diet provokes systemic and cerebral inflammation in rats without inducing obesity. Sci Rep 2021; 11:11252. [PMID: 34045616 PMCID: PMC8160215 DOI: 10.1038/s41598-021-90817-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 05/07/2021] [Indexed: 02/06/2023] Open
Abstract
While the dire cardiometabolic consequences of the hypercaloric modern 'Western' diet are well known, there is not much information on the health impact of a high sucrose diet not inducing weight gain. Here, we tested the hypothesis that rats reared with intermittent binge access to sucrose in addition to normal chow would develop an inflammatory response in brain. To test this hypothesis, we undertook serial PET/MRI scans with the TSPO ligand [18F]DPA714 in a group of (n=9) rats at baseline and again after voluntarily consuming 5% sucrose solution three days a week for three months. Compared to a control group fed with normal chow (n=9), the sucrose rats indeed showed widespread increases in the availability of cerebral binding sites for the microglial marker, despite normal weight gain compared to the control diet group. Subsequent immunofluorescence staining of the brains confirmed the PET findings, showing a widespread 20% increase in the abundance of IBA-1-positive microglia with characteristic 'semi-activated' morphology in the binge sucrose rats, which had 23% lower density of microglial endpoints and 25% lower mean process length compared to microglia in the control rats with ordinary feeding. GFAP immunofluorescence showed no difference in astroglial coverage in the sucrose rats, except for a slight reduction in hypothalamus. The binge sucrose diet-induced neuroinflammation was associated with a significant elevation of white blood cell counts. Taking these results together, we find that long-term intake of sucrose in a binge paradigm, similar in sucrose content to the contemporary Western diet, triggered a low-grade systemic and central inflammation in non-obese rats. The molecular mechanism of this phenomenon remains to be established.
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Affiliation(s)
- Omkar L Patkar
- Macrophage Biology Group, Mater Research, Translational Research Institute, Brisbane, QLD, Australia
- Department of Nuclear Medicine, Inselspital, Bern University, Bern, Switzerland
| | - Abdalla Z Mohamed
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Ashwin Narayanan
- Centre for Advanced Imaging, The University of Queensland, Brisbane, QLD, Australia
| | - Karine Mardon
- Centre for Advanced Imaging, The University of Queensland, Brisbane, QLD, Australia
| | - Gary Cowin
- Centre for Advanced Imaging, The University of Queensland, Brisbane, QLD, Australia
| | - Rajiv Bhalla
- Centre for Advanced Imaging, The University of Queensland, Brisbane, QLD, Australia
| | - Damion H R Stimson
- Centre for Advanced Imaging, The University of Queensland, Brisbane, QLD, Australia
| | - Michael Kassiou
- School of Chemistry, University of Sydney, Sydney, NSW, 2006, Australia
| | - Kate Beecher
- Queensland University of Technology, Translational Research Institute, Brisbane, QLD, Australia
| | - Arnauld Belmer
- Queensland University of Technology, Translational Research Institute, Brisbane, QLD, Australia
| | - Ignatius Alvarez Cooper
- Queensland University of Technology, Translational Research Institute, Brisbane, QLD, Australia
| | - Michael Morgan
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Australia
| | - David A Hume
- Macrophage Biology Group, Mater Research, Translational Research Institute, Brisbane, QLD, Australia
| | - Katharine M Irvine
- Macrophage Biology Group, Mater Research, Translational Research Institute, Brisbane, QLD, Australia
| | - Selena E Bartlett
- Queensland University of Technology, Translational Research Institute, Brisbane, QLD, Australia
| | - Fatima Nasrallah
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Paul Cumming
- Department of Nuclear Medicine, Inselspital, Bern University, Bern, Switzerland.
- School of Psychology and Counselling, Queensland University of Technology, Brisbane, Australia.
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Cumming P, Scheidegger M, Dornbierer D, Palner M, Quednow BB, Martin-Soelch C. Molecular and Functional Imaging Studies of Psychedelic Drug Action in Animals and Humans. Molecules 2021; 26:2451. [PMID: 33922330 PMCID: PMC8122807 DOI: 10.3390/molecules26092451] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 04/15/2021] [Accepted: 04/19/2021] [Indexed: 12/19/2022] Open
Abstract
Hallucinogens are a loosely defined group of compounds including LSD, N,N-dimethyltryptamines, mescaline, psilocybin/psilocin, and 2,5-dimethoxy-4-methamphetamine (DOM), which can evoke intense visual and emotional experiences. We are witnessing a renaissance of research interest in hallucinogens, driven by increasing awareness of their psychotherapeutic potential. As such, we now present a narrative review of the literature on hallucinogen binding in vitro and ex vivo, and the various molecular imaging studies with positron emission tomography (PET) or single photon emission computer tomography (SPECT). In general, molecular imaging can depict the uptake and binding distribution of labelled hallucinogenic compounds or their congeners in the brain, as was shown in an early PET study with N1-([11C]-methyl)-2-bromo-LSD ([11C]-MBL); displacement with the non-radioactive competitor ketanserin confirmed that the majority of [11C]-MBL specific binding was to serotonin 5-HT2A receptors. However, interactions at serotonin 5HT1A and other classes of receptors and pleotropic effects on second messenger pathways may contribute to the particular experiential phenomenologies of LSD and other hallucinogenic compounds. Other salient aspects of hallucinogen action include permeability to the blood-brain barrier, the rates of metabolism and elimination, and the formation of active metabolites. Despite the maturation of radiochemistry and molecular imaging in recent years, there has been only a handful of PET or SPECT studies of radiolabeled hallucinogens, most recently using the 5-HT2A/2C agonist N-(2[11CH3O]-methoxybenzyl)-2,5-dimethoxy- 4-bromophenethylamine ([11C]Cimbi-36). In addition to PET studies of target engagement at neuroreceptors and transporters, there is a small number of studies on the effects of hallucinogenic compounds on cerebral perfusion ([15O]-water) or metabolism ([18F]-fluorodeoxyglucose/FDG). There remains considerable scope for basic imaging research on the sites of interaction of hallucinogens and their cerebrometabolic effects; we expect that hybrid imaging with PET in conjunction with functional magnetic resonance imaging (fMRI) should provide especially useful for the next phase of this research.
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Affiliation(s)
- Paul Cumming
- Department of Nuclear Medicine, Bern University Hospital, CH-3010 Bern, Switzerland
- School of Psychology and Counselling, Queensland University of Technology, Brisbane 4059, Australia
| | - Milan Scheidegger
- Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital of the University of Zurich, CH-8032 Zurich, Switzerland; (M.S.); (D.D.); (B.B.Q.)
| | - Dario Dornbierer
- Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital of the University of Zurich, CH-8032 Zurich, Switzerland; (M.S.); (D.D.); (B.B.Q.)
| | - Mikael Palner
- Odense Department of Clinical Research, University of Southern Denmark, DK-5000 Odense, Denmark;
- Department of Nuclear Medicine, Odense University Hospital, DK-5000 Odense, Denmark
- Neurobiology Research Unit, Copenhagen University Hospital, DK-2100 Copenhagen, Denmark
| | - Boris B. Quednow
- Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital of the University of Zurich, CH-8032 Zurich, Switzerland; (M.S.); (D.D.); (B.B.Q.)
- Neuroscience Center Zurich, University of Zurich and Swiss Federal Institute of Technology Zurich, CH-8058 Zurich, Switzerland
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Meyer J. Novel Phenotypes Detectable with PET in Mood Disorders: Elevated Monoamine Oxidase A and Translocator Protein Level. PET Clin 2018; 12:361-371. [PMID: 28576173 DOI: 10.1016/j.cpet.2017.02.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
As a result of high prevalence and high rates of treatment resistance, major depressive disorder has become the leading cause of death and disability in moderate-income to high-income nations. Poor targeting of phenotypes is a plausible reason for treatment resistance and PET imaging offers a unique role to identify phenotypes. Both increased monoamine oxidase A binding and greater translocator protein 18 kDa binding occur throughout the gray matter during major depressive episodes, including affect-modulating brain regions such as the prefrontal and anterior cingulate cortex, and are detectable with advanced radioligand technology for both of these targets.
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Affiliation(s)
- Jeffrey Meyer
- Research Imaging Centre, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Department of Psychiatry, University of Toronto, 250 College Street, Toronto, Ontario M5T1R8, Canada.
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10
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Cumming P, Burgher B, Patkar O, Breakspear M, Vasdev N, Thomas P, Liu GJ, Banati R. Sifting through the surfeit of neuroinflammation tracers. J Cereb Blood Flow Metab 2018; 38:204-224. [PMID: 29256293 PMCID: PMC5951023 DOI: 10.1177/0271678x17748786] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 10/26/2017] [Accepted: 11/09/2017] [Indexed: 01/09/2023]
Abstract
The first phase of molecular brain imaging of microglial activation in neuroinflammatory conditions began some 20 years ago with the introduction of [11C]-( R)-PK11195, the prototype isoquinoline ligand for translocator protein (18 kDa) (TSPO). Investigations by positron emission tomography (PET) revealed microgliosis in numerous brain diseases, despite the rather low specific binding signal imparted by [11C]-( R)-PK11195. There has since been enormous expansion of the repertoire of TSPO tracers, many with higher specific binding, albeit complicated by allelic dependence of the affinity. However, the specificity of TSPO PET for revealing microglial activation not been fully established, and it has been difficult to judge the relative merits of the competing tracers and analysis methods with respect to their sensitivity for detecting microglial activation. We therefore present a systematic comparison of 13 TSPO PET and single photon computed tomography (SPECT) tracers belonging to five structural classes, each of which has been investigated by compartmental analysis in healthy human brain relative to a metabolite-corrected arterial input. We emphasize the need to establish the non-displaceable binding component for each ligand and conclude with five recommendations for a standard approach to define the cellular distribution of TSPO signals, and to characterize the properties of candidate TSPO tracers.
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Affiliation(s)
- Paul Cumming
- School of Psychology and Counselling and IHBI, Faculty of Health, Queensland University of Technology, Brisbane, Australia
- QIMR Berghofer Institute, Brisbane, Australia
| | - Bjorn Burgher
- QIMR Berghofer Institute, Brisbane, Australia
- Metro North Mental Health Service, Brisbane, Australia
| | - Omkar Patkar
- School of Psychology and Counselling and IHBI, Faculty of Health, Queensland University of Technology, Brisbane, Australia
- QIMR Berghofer Institute, Brisbane, Australia
| | - Michael Breakspear
- QIMR Berghofer Institute, Brisbane, Australia
- Metro North Mental Health Service, Brisbane, Australia
| | - Neil Vasdev
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, MA, USA
- Department of Radiology, Harvard Medical School, Boston, MA, USA
| | - Paul Thomas
- Herston Imaging Research Facility, Faculty of Medicine, University of Queensland Centre for Clinical Research, Herston, Australia
| | - Guo-Jun Liu
- Australian Nuclear Science and Technology Organisation, Lucas Heights, Australia
- National Imaging Facility, Brain and Mind Centre and Faculty of Health Sciences, University of Sydney, Camperdown, Australia
| | - Richard Banati
- Australian Nuclear Science and Technology Organisation, Lucas Heights, Australia
- National Imaging Facility, Brain and Mind Centre and Faculty of Health Sciences, University of Sydney, Camperdown, Australia
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Naoi M, Maruyama W, Shamoto-Nagai M. Type A and B monoamine oxidases distinctly modulate signal transduction pathway and gene expression to regulate brain function and survival of neurons. J Neural Transm (Vienna) 2017; 125:1635-1650. [DOI: 10.1007/s00702-017-1832-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Accepted: 12/18/2017] [Indexed: 02/01/2023]
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Nebel N, Maschauer S, Kuwert T, Hocke C, Prante O. In Vitro and In Vivo Characterization of Selected Fluorine-18 Labeled Radioligands for PET Imaging of the Dopamine D3 Receptor. Molecules 2016; 21:molecules21091144. [PMID: 27589704 PMCID: PMC6272905 DOI: 10.3390/molecules21091144] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 08/25/2016] [Accepted: 08/26/2016] [Indexed: 02/07/2023] Open
Abstract
Cerebral dopamine D3 receptors seem to play a key role in the control of drug-seeking behavior. The imaging of their regional density with positron emission tomography (PET) could thus help in the exploration of the molecular basis of drug addiction. A fluorine-18 labeled D3 subtype selective radioligand would be beneficial for this purpose; however, as yet, there is no such tracer available. The three candidates [18F]1, [18F]2a and [18F]2b were chosen for in vitro and in vivo characterization as radioligands suitable for selective PET imaging of the D3 receptor. Their evaluation included the analysis of radiometabolites and the assessment of non-specific binding by in vitro rat brain autoradiography. While [18F]1 and [18F]2a revealed high non-specific uptake in in vitro rat brain autoradiography, the D3 receptor density was successfully determined on rat brain sections (n = 4) with the candidate [18F]2b offering a Bmax of 20.38 ± 2.67 pmol/g for the islands of Calleja, 19.54 ± 1.85 pmol/g for the nucleus accumbens and 16.58 ± 1.63 pmol/g for the caudate putamen. In PET imaging studies, the carboxamide 1 revealed low signal/background ratios in the rat brain and relatively low uptake in the pituitary gland, while the azocarboxamides [18F]2a and [18F]2b showed binding that was blockable by the D3 receptor ligand BP897 in the ventricular system and the pituitary gland in PET imaging studies in living rats.
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Affiliation(s)
- Natascha Nebel
- Molecular Imaging and Radiochemistry, Department of Nuclear Medicine, Friedrich Alexander University (FAU), Erlangen 91054, Germany.
| | - Simone Maschauer
- Molecular Imaging and Radiochemistry, Department of Nuclear Medicine, Friedrich Alexander University (FAU), Erlangen 91054, Germany.
| | - Torsten Kuwert
- Molecular Imaging and Radiochemistry, Department of Nuclear Medicine, Friedrich Alexander University (FAU), Erlangen 91054, Germany.
| | - Carsten Hocke
- Molecular Imaging and Radiochemistry, Department of Nuclear Medicine, Friedrich Alexander University (FAU), Erlangen 91054, Germany.
| | - Olaf Prante
- Molecular Imaging and Radiochemistry, Department of Nuclear Medicine, Friedrich Alexander University (FAU), Erlangen 91054, Germany.
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