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Pérez-Santos I, Palomero-Gallagher N, Zilles K, Cavada C. Distribution of the Noradrenaline Innervation and Adrenoceptors in the Macaque Monkey Thalamus. Cereb Cortex 2021; 31:4115-4139. [PMID: 34003210 PMCID: PMC8328208 DOI: 10.1093/cercor/bhab073] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 02/18/2021] [Accepted: 03/03/2021] [Indexed: 11/14/2022] Open
Abstract
Noradrenaline (NA) in the thalamus has important roles in physiological, pharmacological, and pathological neuromodulation. In this work, a complete characterization of NA axons and Alpha adrenoceptors distributions is provided. NA axons, revealed by immunohistochemistry against the synthesizing enzyme and the NA transporter, are present in all thalamic nuclei. The most densely innervated ones are the midline nuclei, intralaminar nuclei (paracentral and parafascicular), and the medial sector of the mediodorsal nucleus (MDm). The ventral motor nuclei and most somatosensory relay nuclei receive a moderate NA innervation. The pulvinar complex receives a heterogeneous innervation. The lateral geniculate nucleus (GL) has the lowest NA innervation. Alpha adrenoceptors were analyzed by in vitro quantitative autoradiography. Alpha-1 receptor densities are higher than Alpha-2 densities. Overall, axonal densities and Alpha adrenoceptor densities coincide; although some mismatches were identified. The nuclei with the highest Alpha-1 values are MDm, the parvocellular part of the ventral posterior medial nucleus, medial pulvinar, and midline nuclei. The nucleus with the lowest Alpha-1 receptor density is GL. Alpha-2 receptor densities are highest in the lateral dorsal, centromedian, medial and inferior pulvinar, and midline nuclei. These results suggest a role for NA in modulating thalamic involvement in consciousness, limbic, cognitive, and executive functions.
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Affiliation(s)
- Isabel Pérez-Santos
- Departamento de Anatomía, Histología y Neurociencia, Facultad de Medicina, Universidad Autónoma de Madrid (UAM), Calle Arzobispo Morcillo 4, 28029 Madrid, Spain
| | - Nicola Palomero-Gallagher
- Institute of Neuroscience and Medicine (INM-1), Research Centre Jülich, 52425 Jülich, Germany.,Department of Psychiatry, Psychotherapy and Psychosomatics, Medical Faculty, RWTH Aachen University, 52074 Aachen, Germany.,C. & O. Vogt Institute for Brain Research, Heinrich-Heine-University, 40225 Düsseldorf, Germany
| | - Karl Zilles
- Institute of Neuroscience and Medicine (INM-1), Research Centre Jülich, 52425 Jülich, Germany.,C. & O. Vogt Institute for Brain Research, Heinrich-Heine-University, 40225 Düsseldorf, Germany.,JARA-BRAIN, Jülich-Aachen Research Alliance, 52425 Jülich, Germany
| | - Carmen Cavada
- Departamento de Anatomía, Histología y Neurociencia, Facultad de Medicina, Universidad Autónoma de Madrid (UAM), Calle Arzobispo Morcillo 4, 28029 Madrid, Spain
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Recent advances in radiotracers targeting norepinephrine transporter: structural development and radiolabeling improvements. J Neural Transm (Vienna) 2020; 127:851-873. [PMID: 32274584 PMCID: PMC7223405 DOI: 10.1007/s00702-020-02180-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Accepted: 03/21/2020] [Indexed: 12/13/2022]
Abstract
The norepinephrine transporter (NET) is a major target for the evaluation of the cardiac sympathetic nerve system in patients with heart failure and Parkinson's disease. It is also used in the therapeutic applications against certain types of neuroendocrine tumors, as exemplified by the clinically used 123/131I-MIBG as theranostic single-photon emission computed tomography (SPECT) agent. With the development of more advanced positron emission tomography (PET) technology, more radiotracers targeting NET have been reported, with superior temporal and spatial resolutions, along with the possibility of functional and kinetic analysis. More recently, fluorine-18-labelled NET tracers have drawn increasing attentions from researchers, due to their longer radiological half-life relative to carbon-11 (110 min vs. 20 min), reduced dependence on on-site cyclotrons, and flexibility in the design of novel tracer structures. In the heart, certain NET tracers provide integral diagnostic information on sympathetic innervation and the nerve status. In the central nervous system, such radiotracers can reveal NET distribution and density in pathological conditions. Most radiotracers targeting cardiac NET-function for the cardiac application consistent of derivatives of either norepinephrine or MIBG with its benzylguanidine core structure, e.g. 11C-HED and 18F-LMI1195. In contrast, all NET tracers used in central nervous system applications are derived from clinically used antidepressants. Lastly, possible applications of NET as selective tracers over organic cation transporters (OCTs) in the kidneys and other organs controlled by sympathetic nervous system will also be discussed.
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Ghosh A, Torraville SE, Mukherjee B, Walling SG, Martin GM, Harley CW, Yuan Q. An experimental model of Braak's pretangle proposal for the origin of Alzheimer's disease: the role of locus coeruleus in early symptom development. ALZHEIMERS RESEARCH & THERAPY 2019; 11:59. [PMID: 31266535 PMCID: PMC6607586 DOI: 10.1186/s13195-019-0511-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 06/06/2019] [Indexed: 12/22/2022]
Abstract
Background The earliest brain pathology related to Alzheimer’s disease (AD) is hyperphosphorylated soluble tau in the noradrenergic locus coeruleus (LC) neurons. Braak characterizes five pretangle tau stages preceding AD tangles. Pretangles begin in young humans and persist in the LC while spreading from there to other neuromodulatory neurons and, later, to the cortex. While LC pretangles appear in all by age 40, they do not necessarily result in AD prior to death. However, with age and pretangle spread, more individuals progress to AD stages. LC neurons are lost late, at Braak stages III–IV, when memory deficits appear. It is not clear if LC hyperphosphorylated tau generates the pathology and cognitive changes associated with preclinical AD. We use a rat model expressing pseudohyperphosphorylated human tau in LC to investigate the hypothesis that LC pretangles generate preclinical Alzheimer pathology. Methods We infused an adeno-associated viral vector carrying a human tau gene pseudophosphorylated at 14 sites common in LC pretangles into 2–3- or 14–16-month TH-Cre rats. We used odor discrimination to probe LC dysfunction, and we evaluated LC cell and fiber loss. Results Abnormal human tau was expressed in LC and exhibited somatodendritic mislocalization. In rats infused at 2–3 months old, 4 months post-infusion abnormal LC tau had transferred to the serotonergic raphe neurons. After 7 months, difficult similar odor discrimination learning was impaired. Impairment was associated with reduced LC axonal density in the olfactory cortex and upregulated β1-adrenoceptors. LC infusions in 14–16-month-old rats resulted in more severe outcomes. By 5–6 months post-infusion, rats were impaired even in simple odor discrimination learning. LC neuron number was reduced. Human tau appeared in the microglia and cortical neurons. Conclusions Our animal model suggests, for the first time, that Braak’s hypothesis that human AD originates with pretangle stages is plausible. LC pretangle progression here generates both preclinical AD pathological changes and cognitive decline. The odor discrimination deficits are similar to human odor identification deficits seen with aging and preclinical AD. When initiated in aged rats, pretangle stages progress rapidly and cause LC cell loss. These age-related outcomes are associated with a severe learning impairment consistent with memory decline in Braak stages III–IV. Electronic supplementary material The online version of this article (10.1186/s13195-019-0511-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Abhinaba Ghosh
- Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, A1B 3V6, Canada
| | - Sarah E Torraville
- Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, A1B 3V6, Canada.,Department of Psychology, Faculty of Science, Memorial University of Newfoundland, St. John's, NL, A1B 3X9, Canada
| | - Bandhan Mukherjee
- Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, A1B 3V6, Canada
| | - Susan G Walling
- Department of Psychology, Faculty of Science, Memorial University of Newfoundland, St. John's, NL, A1B 3X9, Canada
| | - Gerard M Martin
- Department of Psychology, Faculty of Science, Memorial University of Newfoundland, St. John's, NL, A1B 3X9, Canada
| | - Carolyn W Harley
- Department of Psychology, Faculty of Science, Memorial University of Newfoundland, St. John's, NL, A1B 3X9, Canada.
| | - Qi Yuan
- Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, A1B 3V6, Canada.
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Arakawa R, Stenkrona P, Takano A, Svensson J, Andersson M, Nag S, Asami Y, Hirano Y, Halldin C, Lundberg J. Venlafaxine ER Blocks the Norepinephrine Transporter in the Brain of Patients with Major Depressive Disorder: a PET Study Using [18F]FMeNER-D2. Int J Neuropsychopharmacol 2019; 22:278-285. [PMID: 30649319 PMCID: PMC6441126 DOI: 10.1093/ijnp/pyz003] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 12/21/2018] [Accepted: 01/09/2019] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND The in vivo binding of clinical dose of venlafaxine on norepinephrine transporter has been questioned because venlafaxine has higher in vitro affinity to serotonin transporter than that to norepinephrine transporter. Although serotonin transporter occupancy of clinically relevant doses of venlafaxine has been reported, there has been no report of norepinephrine transporter occupancy in the human brain. METHODS This was an open-label, single center, exploratory positron emission tomography study. Twelve major depressive disorder patients who had responded to venlafaxine extended-release and 9 control subjects were recruited. Each subject participated in one positron emission tomography measurement with [18F]FMeNER-D2. Binding potential in brain was quantified by the area under the curve ratio method with thalamus as target and white matter as reference regions. The difference of binding potential values between control and patient groups divided to 2 dose ranges were evaluated. Norepinephrine transporter occupancy (%) for all the major depressive disorder patients was calculated using mean binding potential of control subjects as baseline. The relationships between dose or plasma concentration of total active moiety and occupancies of norepinephrine transporter were also estimated. RESULTS The binding potential of the patient group with 150 to 300 mg/d was significantly lower than that in the control subjects group (P = .0004 < .05/2). The norepinephrine transporter occupancy (8-61%) increased in a dose-dependent manner although a clear difference beyond 150 mg/d was not observed. CONCLUSIONS This study demonstrates that clinically relevant doses of venlafaxine extended-release block the norepinephrine transporter of the major depressive disorder patient's brain. The data support the notion that the antidepressant effect of venlafaxine involves a combination of serotonin transporter and norepinephrine transporter blockades.
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Affiliation(s)
- Ryosuke Arakawa
- Centre for Psychiatry Research, Department of Clinical Neuroscience, Karolinska Institutet, & Stockholm Health Care Services, Stockholm County Council, Stockholm, Sweden,Correspondence: Ryosuke Arakawa, MD, PhD, Centre for Psychiatry Research, Department of Clinical Neuroscience, Karolinska Institutet, & Stockholm Health Care Services, Stockholm County Council, Stockholm, Sweden. Post address: Karolinska University Hospital Solna, R5:02, SE-17176 Stockholm, Sweden ()
| | - Per Stenkrona
- Centre for Psychiatry Research, Department of Clinical Neuroscience, Karolinska Institutet, & Stockholm Health Care Services, Stockholm County Council, Stockholm, Sweden
| | - Akihiro Takano
- Centre for Psychiatry Research, Department of Clinical Neuroscience, Karolinska Institutet, & Stockholm Health Care Services, Stockholm County Council, Stockholm, Sweden
| | - Jonas Svensson
- Centre for Psychiatry Research, Department of Clinical Neuroscience, Karolinska Institutet, & Stockholm Health Care Services, Stockholm County Council, Stockholm, Sweden
| | - Max Andersson
- Centre for Psychiatry Research, Department of Clinical Neuroscience, Karolinska Institutet, & Stockholm Health Care Services, Stockholm County Council, Stockholm, Sweden
| | - Sangram Nag
- Centre for Psychiatry Research, Department of Clinical Neuroscience, Karolinska Institutet, & Stockholm Health Care Services, Stockholm County Council, Stockholm, Sweden
| | - Yuko Asami
- Central Nervous System, Medical Affairs, Pfizer Essential Health, Pfizer Japan Inc., Tokyo, Japan
| | - Yoko Hirano
- Central Nervous System, Medical Affairs, Pfizer Essential Health, Pfizer Japan Inc., Tokyo, Japan
| | - Christer Halldin
- Centre for Psychiatry Research, Department of Clinical Neuroscience, Karolinska Institutet, & Stockholm Health Care Services, Stockholm County Council, Stockholm, Sweden
| | - Johan Lundberg
- Centre for Psychiatry Research, Department of Clinical Neuroscience, Karolinska Institutet, & Stockholm Health Care Services, Stockholm County Council, Stockholm, Sweden
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Liebe T, Li M, Colic L, Munk MHJ, Sweeney-Reed CM, Woelfer M, Kretzschmar MA, Steiner J, von Düring F, Behnisch G, Schott BH, Walter M. Ketamine influences the locus coeruleus norepinephrine network, with a dependency on norepinephrine transporter genotype - a placebo controlled fMRI study. NEUROIMAGE-CLINICAL 2018; 20:715-723. [PMID: 30238915 PMCID: PMC6146384 DOI: 10.1016/j.nicl.2018.09.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 08/12/2018] [Accepted: 09/02/2018] [Indexed: 12/14/2022]
Abstract
Background Ketamine is receiving increasing attention as a rapid-onset antidepressant in patients suffering from major depressive disorder (MDD) with treatment resistance or severe suicidal ideation. Ketamine modulates several neurotransmitter systems, including norepinephrine via the norepinephrine transporter (NET), both peripherally and centrally. The locus coeruleus (LC), which has high NET concentration, has been attributed to brain networks involved in depression. Thus we investigated the effects of single-dose of racemic ketamine on the LC using resting state functional MRI. Methods Fifty-nine healthy participants (mean age 25.57 ± 4.72) were examined in a double-blind, randomized, placebo-controlled study with 7 Tesla MRI. We investigated the resting state functional connectivity (rs-fc) of the LC before and one hour after subanesthetic ketamine injection (0.5 mg/kg), as well as associations between its rs-fc and a common polymorphism in the NET gene (rs28386840). Results A significant interaction of drug and time was revealed, and post hoc testing showed decreased rs-fc between LC and the thalamus after ketamine administration compared with baseline levels, including the mediodorsal, ventral anterior, ventral lateral, ventral posterolateral and centromedian nuclei. The rs-fc reduction was more pronounced in NET rs28386840 [AA] homozygous subjects than in [T] carriers. Conclusions We demonstrated acute rs-fc changes after ketamine administration in the central node of the norepinephrine pathway. These findings may contribute to understanding the antidepressant effect of ketamine at the system level, supporting modes of action on networks subserving aberrant arousal regulation in depression. Ketamine decreased connectivity between locus coeruleus and bilateral thalamus in resting state fMRI. This reduction of rs-fc between LC and thalamus was dependent on norepinephrine transporter genotype. The central effects of ketamine involve norepinephrine and attention networks. Antidepressive effects of ketamine may involve LC attention system.
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Affiliation(s)
- Thomas Liebe
- Clinical Affective Neuroimaging Laboratory, Leipziger Str. 44, 39112 Magdeburg, Germany; Leibniz Institute for Neurobiology, Brenneckestraße 6, 39118 Magdeburg, Germany; Clinic for Neuroradiology, University of Magdeburg, Leipziger Str. 44, Magdeburg 39120, Germany; Translational Psychiatry Tübingen, University Hospital Tübingen, Calwerstraße 14, 72076 Tübingen, Germany
| | - Meng Li
- Clinical Affective Neuroimaging Laboratory, Leipziger Str. 44, 39112 Magdeburg, Germany; Department of Neurology, Otto von Guericke University of Magdeburg, Leipziger Str. 44, 39112 Magdeburg, Germany
| | - Lejla Colic
- Clinical Affective Neuroimaging Laboratory, Leipziger Str. 44, 39112 Magdeburg, Germany; Leibniz Institute for Neurobiology, Brenneckestraße 6, 39118 Magdeburg, Germany
| | - Matthias H J Munk
- Department of Psychiatry, University of Tübingen, Calwerstr. 14, 72076 Tübingen, Germany; Department of Systems Neurophysiology, Fachbereich Biologie, Technische Universität Darmstadt, Schnittspahnstraße 10, 64287 Darmstadt, Germany
| | - Catherine M Sweeney-Reed
- Neurocybernetics and Rehabilitation, Department of Neurology, University of Magdeburg, Leipziger Str. 44, Magdeburg 39120, Germany
| | - Marie Woelfer
- Clinical Affective Neuroimaging Laboratory, Leipziger Str. 44, 39112 Magdeburg, Germany; Leibniz Institute for Neurobiology, Brenneckestraße 6, 39118 Magdeburg, Germany; Department of Biomedical Engineering, New Jersey Institute of Technology, 323 Dr Martin Luther King Jr Blvd, Newark, NJ 07102, USA
| | - Moritz A Kretzschmar
- Department of Anesthesiology and Intensive Care Medicine, University of Magdeburg, Leipziger Str. 44, Magdeburg 39120, Germany
| | - Johann Steiner
- Department of Psychiatry, University of Magdeburg, Leipziger Str. 44, Magdeburg 39120, Germany
| | - Felicia von Düring
- Clinical Affective Neuroimaging Laboratory, Leipziger Str. 44, 39112 Magdeburg, Germany; Leibniz Institute for Neurobiology, Brenneckestraße 6, 39118 Magdeburg, Germany
| | - Gusalija Behnisch
- Behavioural Neuroscience, Leibniz Institute for Neurobiology, Brenneckestraße 6, 39118 Magdeburg, Germany
| | - Björn H Schott
- Behavioural Neuroscience, Leibniz Institute for Neurobiology, Brenneckestraße 6, 39118 Magdeburg, Germany; Center for Behavioral Brain Sciences, Otto-von-Guericke-Universität Magdeburg, Universitätsplatz 2, 39106 Magdeburg, Germany; Department of Psychiatry and Psychotherapy, University Medicine Göttingen, von Siebold-Str. 5, 37075 Göttingen, Germany
| | - Martin Walter
- Clinical Affective Neuroimaging Laboratory, Leipziger Str. 44, 39112 Magdeburg, Germany; Leibniz Institute for Neurobiology, Brenneckestraße 6, 39118 Magdeburg, Germany; Department of Neurology, Otto von Guericke University of Magdeburg, Leipziger Str. 44, 39112 Magdeburg, Germany; Department of Psychiatry, University of Magdeburg, Leipziger Str. 44, Magdeburg 39120, Germany; Center for Behavioral Brain Sciences, Otto-von-Guericke-Universität Magdeburg, Universitätsplatz 2, 39106 Magdeburg, Germany; Max Planck Institute for Biological Cybernetics Tübingen, Max-Planck-Ring 8-14, 72076 Tübingen, Germany; Translational Psychiatry Tübingen, University Hospital Tübingen, Calwerstraße 14, 72076 Tübingen, Germany.
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Tadayonnejad R, Ajilore O, Mickey BJ, Crane NA, Hsu DT, Kumar A, Zubieta JK, Langenecker SA. Pharmacological modulation of pulvinar resting-state regional oscillations and network dynamics in major depression. Psychiatry Res 2016; 252:10-18. [PMID: 27148894 PMCID: PMC4892952 DOI: 10.1016/j.pscychresns.2016.04.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Revised: 03/15/2016] [Accepted: 04/26/2016] [Indexed: 01/10/2023]
Abstract
The pulvinar, the largest thalamus nucleus, has rich anatomical connections with several different cortical and subcortical regions suggesting its important involvement in high-level cognitive and emotional functions. Unfortunately, pulvinar dysfunction in psychiatric disorders particularly major depression disorder has not been thoroughly examined to date. In this study we explored the alterations in the baseline regional and network activities of the pulvinar in MDD by applying spectral analysis of resting-state oscillatory activity, functional connectivity and directed (effective) connectivity on resting-state fMRI data acquired from 20 healthy controls and 19 participants with MDD. Furthermore, we tested how pharmacological treatment with duloxetine can modulate the measured local and network variables in ten participants who completed treatment. Our results revealed a frequency-band dependent modulation of power spectrum characteristics of pulvinar regional oscillatory activity. At the network level, we found MDD is associated with aberrant causal interactions between pulvinar and several systems including default-mode and posterior insular networks. It was also shown that duloxetine treatment can correct or overcompensate the pathologic network behavior of the pulvinar. In conclusion, we suggest that pulvinar regional baseline oscillatory activity and its resting-state network dynamics are compromised in MDD and can be modulated therapeutically by pharmacological treatment.
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Affiliation(s)
- Reza Tadayonnejad
- Department of Psychiatry, University of Illinois at Chicago, Chicago, IL, USA.
| | - Olusola Ajilore
- Department of Psychiatry, University of Illinois at Chicago, Chicago, IL, USA
| | - Brian J Mickey
- Department of Psychiatry, University of Michigan, Ann Arbor, MI, USA
| | - Natania A Crane
- Department of Psychiatry, University of Illinois at Chicago, Chicago, IL, USA
| | - David T Hsu
- Department of Psychiatry, University of Michigan, Ann Arbor, MI, USA
| | - Anand Kumar
- Department of Psychiatry, University of Illinois at Chicago, Chicago, IL, USA
| | - Jon-Kar Zubieta
- Department of Psychiatry, University of Michigan, Ann Arbor, MI, USA
| | - Scott A Langenecker
- Department of Psychiatry, University of Illinois at Chicago, Chicago, IL, USA
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Hjorth S, Karlsson C, Jucaite A, Varnäs K, Wählby Hamrén U, Johnström P, Gulyás B, Donohue SR, Pike VW, Halldin C, Farde L. A PET study comparing receptor occupancy by five selective cannabinoid 1 receptor antagonists in non-human primates. Neuropharmacology 2015; 101:519-30. [PMID: 25791528 DOI: 10.1016/j.neuropharm.2015.03.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Revised: 02/05/2015] [Accepted: 03/07/2015] [Indexed: 01/14/2023]
Abstract
There is a medical need for safe and efficacious anti-obesity drugs with acceptable side effect profiles. To mitigate the challenge posed by translating target interaction across species and balancing beneficial vs. adverse effects, a positron emission tomography (PET) approach could help guide clinical dose optimization. Thus, as part of a compound differentiation effort, three novel selective CB1 receptor (CB1R) antagonists, developed by AstraZeneca (AZ) for the treatment of obesity, were compared with two clinically tested reference compounds, rimonabant and taranabant, with regard to receptor occupancy relative to dose and exposure. A total of 42 PET measurements were performed in 6 non-human primates using the novel CB1R antagonist radioligand [(11)C]SD5024. The AZ CB1R antagonists bound in a saturable manner to brain CB1R with in vivo affinities similar to that of rimonabant and taranabant, compounds with proven weight loss efficacy in clinical trials. Interestingly, it was found that exposures corresponding to those needed for optimal clinical efficacy of rimonabant and taranabant resulted in a CB1R occupancy typically around ∼20-30%, thus much lower than what would be expected for classical G-protein coupled receptor (GPCR) antagonists in other therapeutic contexts. These findings are also discussed in relation to emerging literature on the potential usefulness of 'neutral' vs. 'classical' CB1R (inverse agonist) antagonists. The study additionally highlighted the usefulness of the radioligand [(11)C]SD5024 as a specific tracer for CB1R in the primate brain, though an arterial input function would ideally be required in future studies to further assure accurate quantitative analysis of specific binding.
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Affiliation(s)
- Stephan Hjorth
- Biosciences, CVMD Innovative Medicines, AstraZeneca R&D, Mölndal, Sweden
| | - Cecilia Karlsson
- CVMD Translational Medicine Unit, Early Clinical Development, Innovative Medicines, AstraZeneca R&D, Mölndal, Sweden.
| | - Aurelija Jucaite
- AstraZeneca Translational Science Centre and Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Katarina Varnäs
- Centre for Psychiatric Research, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Ulrika Wählby Hamrén
- Quantitative Clinical Pharmacology, Early Clinical Development, Innovative Medicines, AstraZeneca R&D, Mölndal, Sweden
| | - Peter Johnström
- AstraZeneca Translational Science Centre and Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Balázs Gulyás
- Centre for Psychiatric Research, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Sean R Donohue
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA
| | - Victor W Pike
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA
| | - Christer Halldin
- Centre for Psychiatric Research, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Lars Farde
- AstraZeneca Translational Science Centre and Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
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Vanicek T, Spies M, Rami-Mark C, Savli M, Höflich A, Kranz GS, Hahn A, Kutzelnigg A, Traub-Weidinger T, Mitterhauser M, Wadsak W, Hacker M, Volkow ND, Kasper S, Lanzenberger R. The norepinephrine transporter in attention-deficit/hyperactivity disorder investigated with positron emission tomography. JAMA Psychiatry 2014; 71:1340-1349. [PMID: 25338091 PMCID: PMC4699255 DOI: 10.1001/jamapsychiatry.2014.1226] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
IMPORTANCE Attention-deficit/hyperactivity disorder (ADHD) research has long focused on the dopaminergic system's contribution to pathogenesis, although the results have been inconclusive. However, a case has been made for the involvement of the noradrenergic system, which modulates cognitive processes, such as arousal, working memory, and response inhibition, all of which are typically affected in ADHD. Furthermore, the norepinephrine transporter (NET) is an important target for frequently prescribed medication in ADHD. Therefore, the NET is suggested to play a critical role in ADHD. OBJECTIVE To explore the differences in NET nondisplaceable binding potential (NET BPND) using positron emission tomography and the highly selective radioligand (S,S)-[18F]FMeNER-D2 [(S,S)-2-(α-(2-[18F]fluoro[2H2]methoxyphenoxy)benzyl)morpholine] between adults with ADHD and healthy volunteers serving as controls. DESIGN, SETTING, AND PARTICIPANTS Twenty-two medication-free patients with ADHD (mean [SD] age, 30.7 [10.4] years; 15 [68%] men) without psychiatric comorbidities and 22 age- and sex-matched healthy controls (30.9 [10.6] years; 15 [68%] men) underwent positron emission tomography once. A linear mixed model was used to compare NET BPND between groups. MAIN OUTCOMES AND MEASURES The NET BPND in selected regions of interest relevant for ADHD, including the hippocampus, putamen, pallidum, thalamus, midbrain with pons (comprising a region of interest that includes the locus coeruleus), and cerebellum. In addition, the NET BPND was evaluated in thalamic subnuclei (13 atlas-based regions of interest). RESULTS We found no significant differences in NET availability or regional distribution between patients with ADHD and healthy controls in all investigated brain regions (F1,41<0.01; P=.96). Furthermore, we identified no significant association between ADHD symptom severity and regional NET availability. Neither sex nor smoking status influenced NET availability. We determined a significant negative correlation between age and NET availability in the thalamus (R2=0.29; P<.01 corrected) and midbrain with pons, including the locus coeruleus (R2=0.18; P<.01 corrected), which corroborates prior findings of a decrease in NET availability with aging in the human brain. CONCLUSIONS AND RELEVANCE Our results do not indicate involvement of changes in brain NET availability or distribution in the pathogenesis of ADHD. However, the noradrenergic transmitter system may be affected on a different level, such as in cortical regions, which cannot be reliably quantified with this positron emission tomography ligand. Alternatively, different key proteins of noradrenergic neurotransmission might be affected.
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Affiliation(s)
- Thomas Vanicek
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria
| | - Marie Spies
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria
| | - Christina Rami-Mark
- Division of Nuclear Medicine, Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, Vienna, Austria
| | - Markus Savli
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria
| | - Anna Höflich
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria
| | - Georg S. Kranz
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria
| | - Andreas Hahn
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria
| | - Alexandra Kutzelnigg
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria
| | - Tatjana Traub-Weidinger
- Division of Nuclear Medicine, Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, Vienna, Austria
| | - Markus Mitterhauser
- Division of Nuclear Medicine, Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, Vienna, Austria
| | - Wolfgang Wadsak
- Division of Nuclear Medicine, Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, Vienna, Austria
| | - Marcus Hacker
- Division of Nuclear Medicine, Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, Vienna, Austria
| | - Nora D. Volkow
- National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland
| | - Siegfried Kasper
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria
| | - Rupert Lanzenberger
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria
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9
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Vase KH, Peters D, Nielsen EØ, Alstrup AKO, Bender D. [11C]NS8880, a promising PET radiotracer targeting the norepinephrine transporter. Nucl Med Biol 2014; 41:758-64. [PMID: 25127515 DOI: 10.1016/j.nucmedbio.2014.06.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Revised: 06/05/2014] [Accepted: 06/17/2014] [Indexed: 10/25/2022]
Abstract
INTRODUCTION Positron emission tomography (PET) imaging of the norepinephrine transporter (NET) is still hindered by the availability of useful PET imaging probes. The present study describes the radiosynthesis and pre-clinical evaluation of a new compound, exo-3-(6-methoxypyridin-2-yloxy)-8-H-8-azabicyclo[3.2.1]octane (NS8880), targeting NET. NS8880 has an in vitro binding profile comparable to desipramine and is structurally not related to reboxetine. METHODS Labeling of NS8880 with [(11)C] was achieved by a non-conventional technique: substitution of pyridinyl fluorine with [(11)C]methanolate in a Boc-protected precursor. The isolated [(11)C]NS8880 was evaluated pre-clinically both in a pig model (PET scanning) and in a rat model (μPET scanning) and compared to (S,S)-[(11)C]-O-methylreboxetine ([(11)C]MeNER). RESULTS The radiolabeling technique yielded [(11)C]NS8880 in low (<10%) but still useful yields with high purity. The PET in vivo evaluation in pig and rat revealed a rapid brain uptake of [(11)C]NS8880 and fast obtaining of equilibrium. Highest binding was observed in thalamic and hypothalamic regions. Pretreatment with desipramine efficiently reduced binding of [(11)C]NS8880. CONCLUSION Based on the pre-clinical results obtained so far [(11)C]NS8880 displays promising properties for PET imaging of NET.
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Affiliation(s)
- Karina H Vase
- PET Center, Aarhus University Hospital, DK-8000 Aarhus C, Denmark.
| | - Dan Peters
- DanPET AB, Rosenstigen 7, SE-216 19 Malmö, Sweden
| | | | - Aage K O Alstrup
- PET Center, Aarhus University Hospital, DK-8000 Aarhus C, Denmark
| | - Dirk Bender
- PET Center, Aarhus University Hospital, DK-8000 Aarhus C, Denmark
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10
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Norepinephrine transporter occupancy in the human brain after oral administration of quetiapine XR. Int J Neuropsychopharmacol 2013; 16:2235-44. [PMID: 23809226 DOI: 10.1017/s1461145713000680] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Quetiapine, originally developed as an antipsychotic, demonstrates efficacy in clinical studies of schizophrenia, bipolar mania and depression, major depressive disorder and generalized anxiety disorder. This broad spectrum of efficacy was not predicted from the preclinical pharmacology of quetiapine. Binding studies in vitro show that quetiapine and its major active human metabolite, norquetiapine, have moderate to high affinity for dopamine D2 and serotonin 5-HT2A receptors, while norquetiapine alone has high affinity for the norepinephrine transporter (NET). This positron emission tomography (PET) study measured NET occupancy in human subjects treated with extended-release quetiapine (quetiapine XR) at doses relevant in the treatment of depression. PET measurements using the specific NET radioligand (S,S)-[(18)F]FMeNER-D2 were performed before and after quetiapine XR treatment at 150 and 300 mg/d for 6-8 d in nine healthy males (aged 21-33 yr). Regions of interest were defined for the thalamus, using the caudate as reference region. NET occupancy was calculated using a target:reference region ratio method. Plasma concentrations of quetiapine and norquetiapine were monitored during PET measurements. Following quetiapine XR treatment, the mean NET occupancy in the thalamus was 19 and 35%, respectively, at quetiapine XR doses of 150 and 300 mg/d. The estimated plasma concentration of norquetiapine corresponding to 50% NET occupancy was 161 ng/ml. This is the first demonstration of NET occupancy by an antipsychotic in the human brain. NET inhibition is accepted as a mechanism of antidepressant activity. NET occupancy may therefore contribute to the broad spectrum of efficacy of quetiapine.
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Enge S, Fleischhauer M, Lesch KP, Reif A, Strobel A. Serotonergic modulation in executive functioning: Linking genetic variations to working memory performance. Neuropsychologia 2011; 49:3776-85. [DOI: 10.1016/j.neuropsychologia.2011.09.038] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2011] [Revised: 09/10/2011] [Accepted: 09/25/2011] [Indexed: 12/16/2022]
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12
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The roles of dopamine and noradrenaline in the pathophysiology and treatment of attention-deficit/hyperactivity disorder. Biol Psychiatry 2011; 69:e145-57. [PMID: 21550021 DOI: 10.1016/j.biopsych.2011.02.036] [Citation(s) in RCA: 415] [Impact Index Per Article: 31.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2010] [Revised: 01/16/2011] [Accepted: 02/15/2011] [Indexed: 12/14/2022]
Abstract
Through neuromodulatory influences over fronto-striato-cerebellar circuits, dopamine and noradrenaline play important roles in high-level executive functions often reported to be impaired in attention-deficit/hyperactivity disorder (ADHD). Medications used in the treatment of ADHD (including methylphenidate, dextroamphetamine and atomoxetine) act to increase brain catecholamine levels. However, the precise prefrontal cortical and subcortical mechanisms by which these agents exert their therapeutic effects remain to be fully specified. Herein, we review and discuss the present state of knowledge regarding the roles of dopamine (DA) and noradrenaline in the regulation of corticostriatal circuits, with a focus on the molecular neuroimaging literature (both in ADHD patients and in healthy subjects). Recent positron emission tomography evidence has highlighted the utility of quantifying DA markers, at baseline or following drug administration, in striatal subregions governed by differential cortical connectivity. This approach opens the possibility of characterizing the neurobiological underpinnings of ADHD (and associated cognitive dysfunction) and its treatment by targeting specific neural circuits. It is anticipated that the application of refined and novel positron emission tomography methodology will help to disentangle the overlapping and dissociable contributions of DA and noradrenaline in the prefrontal cortex, thereby aiding our understanding of ADHD and facilitating new treatments.
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Sekine M, Maeda J, Shimada H, Nogami T, Arakawa R, Takano H, Higuchi M, Ito H, Okubo Y, Suhara T. Central nervous system drug evaluation using positron emission tomography. CLINICAL PSYCHOPHARMACOLOGY AND NEUROSCIENCE 2011; 9:9-16. [PMID: 23431048 PMCID: PMC3568655 DOI: 10.9758/cpn.2011.9.1.9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/31/2010] [Revised: 01/18/2011] [Accepted: 01/19/2011] [Indexed: 12/20/2022]
Abstract
In conventional pharmacological research in the field of mental disorders, pharmacological effect and dose have been estimated by ethological approach and in vitro data of affinity to the site of action. In addition, the frequency of administration has been estimated from drug kinetics in blood. However, there is a problem regarding an objective index of drug effects in the living body. Furthermore, the possibility that the concentration of drug in blood does not necessarily reflect the drug kinetics in target organs has been pointed out. Positron emission tomography (PET) techniques have made progress for more than 20 years, and made it possible to measure the distribution and kinetics of small molecule components in living brain. In this article, we focused on rational drug dosing using receptor occupancy and proof-of-concept of drugs in the drug development process using PET.
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Affiliation(s)
- Mizuho Sekine
- Molecular Neuroimaging Group, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba, Japan. ; Department of Neuropsychiatry, Nippon Medical School, Tokyo, Japan
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14
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Tavares AAS, Jobson NK, Dewar D, Sutherland A, Pimlott SL. Development of the radiosynthesis of high-specific-activity 123I-NKJ64. Nucl Med Biol 2011; 38:493-500. [PMID: 21531286 DOI: 10.1016/j.nucmedbio.2010.11.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2010] [Revised: 10/15/2010] [Accepted: 11/04/2010] [Indexed: 11/28/2022]
Abstract
INTRODUCTION (123)I-NKJ64, a reboxetine analogue, is currently under development as a potential novel single photon emission computed tomography radiotracer for imaging the noradrenaline transporter in brain. This study describes the development of the radiosynthesis of (123)I-NKJ64, highlighting the advantages and disadvantages, pitfalls and solutions encountered while developing the final radiolabelling methodology. METHODS The synthesis of (123)I-NKJ64 was evaluated using an electrophilic iododestannylation method, where a Boc-protected trimethylstannyl precursor was radioiodinated using peracetic acid as an oxidant and deprotection was investigated using either trifluoroacetic acid (TFA) or 2 M hydrochloric acid (HCl). RESULTS Radioiodination of the Boc-protected trimethylstannyl precursor was achieved with an incorporation yield of 92±6%. Deprotection with 2 M HCl produced (123)I-NKJ64 with the highest radiochemical yield of 98.05±1.63% compared with 83.95±13.24% with TFA. However, the specific activity of the obtained (123)I-NKJ64 was lower when measured after using 2 M HCl (0.15±0.23 Ci/μmol) as the deprotecting agent in comparison to TFA (1.76±0.60 Ci/μmol). Further investigation of the 2 M HCl methodology found a by-product, identified as the deprotected proto-destannylated precursor, which co-eluted with (123)I-NKJ64 during the high-performance liquid chromatography (HPLC) purification. CONCLUSIONS The radiosynthesis of (123)I-NKJ64 was achieved with good isolated radiochemical yield of 68% and a high specific activity of 1.8 Ci/μmol. TFA was found to be the most suitable deprotecting agent, since 2 M HCl generated a by-product that could not be fully separated from (123)I-NKJ64 using the HPLC methodology investigated. This study highlights the importance of HPLC purification and accurate measurement of specific activity while developing new radiosynthesis methodologies.
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Affiliation(s)
- Adriana Alexandre S Tavares
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, G12 8QQ Glasgow, UK.
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15
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Kalk NJ, Nutt DJ, Lingford-Hughes AR. The role of central noradrenergic dysregulation in anxiety disorders: evidence from clinical studies. J Psychopharmacol 2011; 25:3-16. [PMID: 20530586 DOI: 10.1177/0269881110367448] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The nature of the noradrenergic dysregulation in clinical anxiety disorders remains unclear. In panic disorder, the predominant view has been that central noradrenergic neuronal networks and/or the sympathetic nervous system was normal in patients at rest, but hyper-reactive to specific stimuli, for example carbon dioxide. These ideas have been extended to other anxiety disorders, which share with panic disorder characteristic subjective anxiety and physiological symptoms of excess sympathetic activity. For example, Generalized Anxiety Disorder is characterized by chronic free-floating anxiety, muscle tension, palpitation and insomnia. It has been proposed that there is chronic central hypersecretion of noradrenaline in Generalized Anxiety Disorder, with consequent hyporesponsiveness of central post-synaptic receptors. With regards to other disorders, it has been suggested that there is noradrenergic involvement or derangement, but a more specific hypothesis has not been enunciated. This paper reviews the evidence for noradrenergic dysfunction in anxiety disorders, derived from indirect measures of noradrenergic function in clinical populations.
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Affiliation(s)
- N J Kalk
- Department of Psychopharmacology, University of Bristol, Bristol, UK.
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16
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Tavares AAS, Jobson NK, Dewar D, Sutherland A, Pimlott SL. ¹²³I-NKJ64: a novel single photon emission computed tomography radiotracer for imaging the noradrenaline transporter in brain. Synapse 2010; 65:658-67. [PMID: 21157929 DOI: 10.1002/syn.20895] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2010] [Accepted: 11/17/2010] [Indexed: 11/11/2022]
Abstract
Dysregulation of noradrenergic function has been implicated in a variety of psychiatric and neurodegenerative disorders, including depression and Alzheimer's disease. The noradrenaline transporter (NAT) is a major target for antidepressant drugs, including reboxetine, a selective noradrenaline reuptake inhibitor. Therefore, the development of a radiotracer for imaging of the NAT is desirable. In this study, NKJ64, a novel iodinated analog of reboxetine, was radiolabeled and evaluated as a potential single photon emission computerized tomography (SPECT) radiotracer for imaging the NAT in brain. Biological evaluation of the novel radiotracer, ¹²³/¹²⁵I-NKJ64, was carried out in rats using: in vitro ligand binding assays; in vitro and ex vivo autoradiography; in vivo biodistribution studies and ex vivo pharmacological blocking studies. ¹²⁵I-NKJ64 displayed saturable binding with high affinity for NAT in cortical homogenates (K(D) = 4.82 ± 0.87 nM, mean ± SEM, n = 3). In vitro and ex vivo autoradiography showed the regional distribution of ¹²³I-NKJ64 binding to be consistent with the known density of NAT in brain. Following i.v. injection there was rapid uptake of ¹²³I-NKJ64 in brain, with maximum uptake of 2.93% ± 0.14% (mean ± SEM, n = 3) of the injected dose. The specific to nonspecific ratio (locus coeruleus:caudate putamen) of ¹²³I-NKJ64 uptake measured by ex vivo autoradiography was 2.8 at 30 min post i.v. injection. The prior administration of reboxetine significantly reduced the accumulation of ¹²³I-NKJ64 in the locus coeruleus (>50% blocking). The data indicate that further evaluation of ¹²³I-NKJ64 in nonhuman primates is warranted in order to determine its utility as a SPECT radiotracer for imaging of NAT in brain.
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Affiliation(s)
- Adriana Alexandre S Tavares
- Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, G128QQ Glasgow, Scotland, United Kingdom.
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17
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Sekine M, Arakawa R, Ito H, Okumura M, Sasaki T, Takahashi H, Takano H, Okubo Y, Halldin C, Suhara T. Norepinephrine transporter occupancy by antidepressant in human brain using positron emission tomography with (S,S)-[18F]FMeNER-D2. Psychopharmacology (Berl) 2010; 210:331-6. [PMID: 20309528 DOI: 10.1007/s00213-010-1824-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2009] [Accepted: 03/03/2010] [Indexed: 10/19/2022]
Abstract
RATIONALE Central norepinephrine transporter (NET) is one of the main targets of antidepressants. Although the measurement of NET occupancy has been attempted in humans, the outcomes have been inconclusive. OBJECTIVE In this study, the occupancy of NET by different doses of an antidepressant, nortriptyline, was measured using positron emission tomography (PET) with (S,S)-[(18)F]FMeNER-D(2). MATERIALS AND METHODS PET scans using (S,S)-[(18)F]FMeNER-D(2) were performed on six healthy men before and after oral administration of a single oral dose of nortriptyline (10-75 mg). After a bolus i.v. injection of (S,S)-[(18)F]FMeNER-D(2), dynamic scanning was performed for 0-90 min, followed by scanning for 120-180 min. The ratio of the thalamus-to-caudate areas under the curve (120-180 min) minus 1 was used as the binding potential (BP(ND)) for NET. NET occupancy was calculated as the percentage reduction of BP(ND). Venous blood samples were taken to measure the concentrations of nortriptyline just before injection of the tracer and at 180 min after the injection. RESULTS Mean NET occupancies by nortriptyline were 16.4% at 10 mg, 33.2% at 25 mg, and 41.1% at 75 mg. The mean plasma concentration of nortriptyline was less than the lower limit of detection at 10 mg, 23.7 ng/mL at 25 mg, and 50.5 ng/mL at 75 mg. Estimated ED(50) was 76.8 mg of administration dose and 59.8 ng/mL of plasma concentration. CONCLUSIONS NET occupancy by nortriptyline corresponding to the administration dose of 10-75 mg or plasma concentration was observed from 16% to 41%.
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Affiliation(s)
- Mizuho Sekine
- Molecular Neuroimaging Group, Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1, Anagawa, Inage-ku, Chiba, 263-8555, Japan.
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The norepinephrine transporter (NET) radioligand (S,S)-[18F]FMeNER-D2 shows significant decreases in NET density in the human brain in Alzheimer's disease: A post-mortem autoradiographic study. Neurochem Int 2010; 56:789-98. [DOI: 10.1016/j.neuint.2010.03.001] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2010] [Accepted: 03/01/2010] [Indexed: 11/19/2022]
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Positron emission tomography neuroimaging for a better understanding of the biology of ADHD. Neuropharmacology 2009; 57:601-7. [DOI: 10.1016/j.neuropharm.2009.08.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2009] [Revised: 07/29/2009] [Accepted: 08/04/2009] [Indexed: 11/20/2022]
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Grefkes C, Wang LE, Eickhoff SB, Fink GR. Noradrenergic modulation of cortical networks engaged in visuomotor processing. ACTA ACUST UNITED AC 2009; 20:783-97. [PMID: 19687293 DOI: 10.1093/cercor/bhp144] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Both animal and human data suggest that stimulation of the noradrenergic system may influence neuronal excitability in regions engaged in sensory processing and visuospatial attention. We tested the hypothesis that the neural mechanisms subserving motor performance in tasks relying on the visuomotor control of goal-directed hand movements might be modulated by noradrenergic influences. Healthy subjects were stimulated using the selective noradrenaline reuptake inhibitor reboxetine (RBX) in a placebo-controlled crossover design. Functional magnetic resonance imaging and dynamic causal modeling (DCM) were used to assess drug-related changes in blood oxygen level-dependent activity and interregional connectivity while subjects performed a joystick task requiring goal-directed movements. Improved task performance under RBX was associated with increased activity in right visual, intraparietal and superior frontal cortex (premotor/frontal eye field). DCM revealed that the neuronal coupling among these regions was significantly enhanced when subjects were stimulated with RBX. Concurrently, right intraparietal cortex and right superior frontal cortex exerted a stronger driving influence on visuomotor areas of the left hemisphere, including SMA and M1. These effects were independent from task difficulty. The data suggest that stimulating noradrenergic mechanisms may rearrange the functional network architecture within and across the hemispheres, for example, by synaptic gating, thereby optimizing motor behavior.
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Affiliation(s)
- Christian Grefkes
- Neuromodulation & Neurorehabilitation, Max Planck Institute for Neurological Research, 50931 Cologne, Germany.
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Takano A, Gulyás B, Varrone A, Maguire RP, Halldin C. Saturated norepinephrine transporter occupancy by atomoxetine relevant to clinical doses: a rhesus monkey study with (S,S)-[(18)F]FMeNER-D (2). Eur J Nucl Med Mol Imaging 2009; 36:1308-14. [PMID: 19300997 DOI: 10.1007/s00259-009-1118-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2009] [Accepted: 03/02/2009] [Indexed: 11/27/2022]
Abstract
PURPOSE In a previous PET study on norepinephrine transporter (NET) occupancy in the nonhuman primate brain, the relationship between NET occupancy and atomoxetine plasma concentration, and occupancies among different brain regions, were not demonstrated adequately. It may therefore be difficult to translate the results to the clinical situations. In the present study, the detailed change of NET occupancy was investigated among a wider range of doses in a more advanced manner. METHODS Two rhesus monkeys were examined using a high-resolution PET system with (S,S)-[(18)F]FMeNER-D(2) under baseline conditions and after steady-state infusion of different doses of atomoxetine (0.003 to 0.12 mg/kg per hour). NET occupancy of the thalamus, brainstem and anterior cingulate cortex was calculated using BP(ND) obtained with the simplified reference tissue model. RESULTS NET occupancy increased regionally and uniformly as the plasma concentration of atomoxetine increased. The estimated Kd value (the amount to occupy 50% of NET) in the thalamus was 16 ng/ml. CONCLUSION The results indicate that clinical doses of atomoxetine would occupy NET almost completely.
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Affiliation(s)
- Akihiro Takano
- Department of Clinical Neuroscience, Psychiatry Section, Karolinska Institutet, S-171 76, Stockholm, Sweden.
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