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Borchert RJ, Rittman T, Rae CL, Passamonti L, Jones SP, Vatansever D, Vázquez Rodríguez P, Ye Z, Nombela C, Hughes LE, Robbins TW, Rowe JB. Atomoxetine and citalopram alter brain network organization in Parkinson's disease. Brain Commun 2019; 1:fcz013. [PMID: 31886460 PMCID: PMC6924537 DOI: 10.1093/braincomms/fcz013] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Revised: 07/23/2019] [Accepted: 08/20/2019] [Indexed: 11/12/2022] Open
Abstract
Parkinson’s disease has multiple detrimental effects on motor and cognitive systems in the brain. In contrast to motor deficits, cognitive impairments in Parkinson’s disease are usually not ameliorated, and can even be worsened, by dopaminergic treatments. Recent evidence has shown potential benefits from restoring other neurotransmitter deficits, including noradrenergic and serotonergic transmission. Here, we study global and regional brain network organization using task-free imaging (also known as resting-state), which minimizes performance confounds and the bias towards predetermined networks. Thirty-three patients with idiopathic Parkinson’s disease were studied three times in a double-blinded, placebo-controlled counter-balanced crossover design, following placebo, 40 mg oral atomoxetine (selective noradrenaline reuptake inhibitor) or 30 mg oral citalopram (selective serotonin reuptake inhibitor). Neuropsychological assessments were performed outside the scanner. Seventy-six controls were scanned without medication to provide normative data for comparison to the patient cohort. Graph theoretical analysis of task-free brain connectivity, with a random 500-node parcellation, was used to measure the effect of disease in placebo-treated state (versus unmedicated controls) and pharmacological intervention (drug versus placebo). Relative to controls, patients on placebo had executive impairments (reduced fluency and inhibitory control), which was reflected in dysfunctional network dynamics in terms of reduced clustering coefficient, hub degree and hub centrality. In patients, atomoxetine improved fluency in proportion to plasma concentration (P = 0.006, r2 = 0.24), and improved response inhibition in proportion to increased hub Eigen centrality (P = 0.044, r2 = 0.14). Citalopram did not improve fluency or inhibitory control, but its influence on network integration and efficiency depended on disease severity: clustering (P = 0.01, r2 = 0.22), modularity (P = 0.043, r2 = 0.14) and path length (P = 0.006, r2 = 0.25) increased in patients with milder forms of Parkinson’s disease, but decreased in patients with more advanced disease (Unified Parkinson’s Disease Rating Scale motor subscale part III > 30). This study supports the use of task-free imaging of brain networks in translational pharmacology of neurodegenerative disorders. We propose that hub connectivity contributes to cognitive performance in Parkinson’s disease, and that noradrenergic treatment strategies can partially restore the neural systems supporting executive function.
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Affiliation(s)
- Robin J Borchert
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Timothy Rittman
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Charlotte L Rae
- Sackler Centre for Consciousness Science, University of Sussex, Brighton, UK.,School of Psychology, University of Sussex, Falmer, UK
| | - Luca Passamonti
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK.,Department of Biomedical Sciences, National Research Council, Institute of Bioimaging and Molecular Physiology, Segrate, Italy
| | - Simon P Jones
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Deniz Vatansever
- Institute of Science and Technology for Brain-inspired Intelligence, Fudan University, Shanghai, PR China
| | | | - Zheng Ye
- Key Laboratory of Mental Health, Institute of Psychology, Chinese Academy of Sciences, Beijing, China
| | - Cristina Nombela
- Department of Biological and Health Psychology, Universidad Autónoma de Madrid, Madrid, Spain.,Neurosurgery Department, Hospital Clínico San Carlos, Madrid, Spain
| | - Laura E Hughes
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK.,MRC Cognition and Brain Sciences Unit, University of Cambridge, Cambridge, UK
| | - Trevor W Robbins
- Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK
| | - James B Rowe
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK.,MRC Cognition and Brain Sciences Unit, University of Cambridge, Cambridge, UK.,Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK
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2
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López-Picón FR, Kirjavainen AK, Forsback S, Takkinen JS, Peters D, Haaparanta-Solin M, Solin O. In vivo characterization of a novel norepinephrine transporter PET tracer [ 18F]NS12137 in adult and immature Sprague-Dawley rats. Am J Cancer Res 2019; 9:11-19. [PMID: 30662550 PMCID: PMC6332804 DOI: 10.7150/thno.29740] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 11/16/2018] [Indexed: 12/31/2022] Open
Abstract
Norepinephrine modulates cognitive processes such as working and episodic memory. Pathological changes in norepinephrine and norepinephrine transporter (NET) function and degeneration of the locus coeruleus produce irreversible impairments within the whole norepinephrine system, disrupting cognitive processes. Monitoring these changes could enhance diagnostic accuracy and support development of novel therapeutic components for several neurodegenerative diseases. Thus, we aimed to develop a straightforward nucleophilic fluorination method with high molar activity for the novel NET radiotracer [18F]NS12137 and to demonstrate the ability of [18F]NS12137 to quantify changes in NET expression. Methods: We applied an 18F-radiolabeling method in which a brominated precursor was debrominated by nucleophilic 18F-fluorination in dimethyl sulfoxide. Radiolabeling was followed by a deprotection step, purification, and formulation of the radiotracer. The [18F]NS12137 brain uptake and distribution were studied with in vivo PET/CT and ex vivo autoradiography using both adult and immature Sprague-Dawley rats because postnatal NET expression peaks at 10-20 days post birth. The NET specificity for the tracer was demonstrated by pretreatment of the animals with nisoxetine, which is well-known to have a high affinity for NET. Results: [18F]NS12137 was successfully synthesized with radiochemical yields of 18.6±5.6%, radiochemical purity of >99%, and molar activity of >500 GBq/μmol at the end of synthesis. The in vivo [18F]NS12137 uptake showed peak standard uptake values (SUV) of over 1.5 (adult) and 2.2 (immature) in the different brain regions. Peak SUV/30 min and peak SUV/60 min ratios were calculated for the different brain regions of the adult and immature rats, with a peak SUV/60 min ratio of more than 4.5 in the striatum of adult rats. As expected, in vivo studies demonstrated uptake of the tracer in brain areas rich in NET, particularly thalamus, neocortex, and striatum, and remarkably also in the locus coeruleus, a quite small volume for imaging with PET. The uptake was significantly higher in immature rats compared to the adult animals. Ex vivo studies using autoradiography showed very strong specific binding in NET-rich areas such as the locus coeruleus and the bed nucleus of the stria terminalis, and high binding in larger grey matter areas such as the neocortex and striatum. The uptake of [18F]NS12137 was dramatically reduced both in vivo and ex vivo by pretreatment with nisoxetine, demonstrating the specificity of binding. Conclusions: [18F]NS12137 was synthesized in good yield and high molar activity and demonstrated the characteristics of a good radiotracer, such as good brain penetration, fast washout, and high specific binding to NET.
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3
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Guedj C, Monfardini E, Reynaud AJ, Farnè A, Meunier M, Hadj-Bouziane F. Boosting Norepinephrine Transmission Triggers Flexible Reconfiguration of Brain Networks at Rest. Cereb Cortex 2018; 27:4691-4700. [PMID: 27600848 DOI: 10.1093/cercor/bhw262] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 08/01/2016] [Indexed: 12/19/2022] Open
Abstract
The locus coeruleus-norepinephrine (LC-NE) system is thought to act as a reset signal allowing brain network reorganization in response to salient information in the environment. However, no direct evidence of NE-dependent whole-brain reorganization has ever been described. We used resting-state functional magnetic resonance imaging in monkeys to investigate the impact of NE-reuptake inhibition on whole-brain connectivity patterns. We found that boosting NE transmission changes functional connectivity between and within resting-state networks. It modulated the functional connectivity pattern of a brainstem network including the LC region and interactions between associative and sensory-motor networks as well as within sensory-motor networks. Among the observed changes, those involving the fronto-parietal attention network exhibited a unique pattern of uncoupling with other sensory-motor networks and correlation switching from negative to positive with the brainstem network that included the LC nucleus. These findings provide the first empirical evidence of NE-dependent large-scale brain network reorganization and further demonstrate that the fronto-parietal attention network represents a central feature within this reorganization.
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Affiliation(s)
- Carole Guedj
- ImpAct Team, Lyon Neuroscience Research Center, INSERM U1028, CNRS UMR5292, Lyon F-69000, France.,University UCBL Lyon 1, F-69000, France
| | - Elisabetta Monfardini
- ImpAct Team, Lyon Neuroscience Research Center, INSERM U1028, CNRS UMR5292, Lyon F-69000, France.,University UCBL Lyon 1, F-69000, France.,Institut de Médecine Environnementale, Paris F-75007, France
| | - Amélie J Reynaud
- ImpAct Team, Lyon Neuroscience Research Center, INSERM U1028, CNRS UMR5292, Lyon F-69000, France.,University UCBL Lyon 1, F-69000, France
| | - Alessandro Farnè
- ImpAct Team, Lyon Neuroscience Research Center, INSERM U1028, CNRS UMR5292, Lyon F-69000, France.,University UCBL Lyon 1, F-69000, France
| | - Martine Meunier
- ImpAct Team, Lyon Neuroscience Research Center, INSERM U1028, CNRS UMR5292, Lyon F-69000, France.,University UCBL Lyon 1, F-69000, France
| | - Fadila Hadj-Bouziane
- ImpAct Team, Lyon Neuroscience Research Center, INSERM U1028, CNRS UMR5292, Lyon F-69000, France.,University UCBL Lyon 1, F-69000, France
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4
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Baladi MG, Forster MJ, Gatch MB, Mailman RB, Hyman DL, Carter LP, Janowsky A. Characterization of the Neurochemical and Behavioral Effects of Solriamfetol (JZP-110), a Selective Dopamine and Norepinephrine Reuptake Inhibitor. J Pharmacol Exp Ther 2018; 366:367-376. [PMID: 29891587 DOI: 10.1124/jpet.118.248120] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Accepted: 06/04/2018] [Indexed: 11/22/2022] Open
Abstract
Excessive sleepiness (ES) is associated with several sleep disorders, including narcolepsy and obstructive sleep apnea (OSA). A role for monoaminergic systems in treating these conditions is highlighted by the clinical use of US Food and Drug Administration-approved drugs that act on these systems, such as dextroamphetamine, methylphenidate, modafinil, and armodafinil. Solriamfetol (JZP-110) is a wake-promoting agent that is currently being evaluated to treat ES in patients with narcolepsy or OSA. Clinical and preclinical data suggest that the wake-promoting effects of solriamfetol differ from medications such as modafinil and amphetamine. The goal of the current studies was to characterize the mechanism of action of solriamfetol at monoamine transporters using in vitro and in vivo assays. Results indicate that solriamfetol has dual reuptake inhibition activity at dopamine (DA; IC50 = 2.9 μM) and norepinephrine (NE; IC50 = 4.4 μM) transporters, and this activity is associated in vivo with increased extracellular concentration of DA and NE as measured by microdialysis. Solriamfetol has negligible functional activity at the serotonin transporter (IC50 > 100 μM). Moreover, the wake-promoting effects of solriamfetol are probably owing to activity at DA and NE transporters rather than other neurotransmitter systems, such as histamine or orexin. The dual activity of solriamfetol at DA and NE transporters and the lack of significant monoamine-releasing properties of solriamfetol might explain the differences in the in vivo effects of solriamfetol compared with modafinil or amphetamine. Taken together, these data suggest that solriamfetol may offer an important advancement in the treatment of ES in patients with narcolepsy or OSA.
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Affiliation(s)
- Michelle G Baladi
- Jazz Pharmaceuticals, Palo Alto, California (M.G.B., D.L.H., L.P.C.); Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, Texas (M.J.F., M.B.G.); Departments of Pharmacology and Neurology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania (R.B.M.); University of Arkansas for Medical Sciences, Little Rock, Arkansas (L.P.C.); Research and Development Service, Veterans Affairs Portland Health Care System, Portland, Oregon (A.J.); and Departments of Psychiatry and Behavioral Neuroscience, and Methamphetamine Abuse Research Center, Oregon Health and Science University, Portland, Oregon (A.J.)
| | - Michael J Forster
- Jazz Pharmaceuticals, Palo Alto, California (M.G.B., D.L.H., L.P.C.); Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, Texas (M.J.F., M.B.G.); Departments of Pharmacology and Neurology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania (R.B.M.); University of Arkansas for Medical Sciences, Little Rock, Arkansas (L.P.C.); Research and Development Service, Veterans Affairs Portland Health Care System, Portland, Oregon (A.J.); and Departments of Psychiatry and Behavioral Neuroscience, and Methamphetamine Abuse Research Center, Oregon Health and Science University, Portland, Oregon (A.J.)
| | - Michael B Gatch
- Jazz Pharmaceuticals, Palo Alto, California (M.G.B., D.L.H., L.P.C.); Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, Texas (M.J.F., M.B.G.); Departments of Pharmacology and Neurology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania (R.B.M.); University of Arkansas for Medical Sciences, Little Rock, Arkansas (L.P.C.); Research and Development Service, Veterans Affairs Portland Health Care System, Portland, Oregon (A.J.); and Departments of Psychiatry and Behavioral Neuroscience, and Methamphetamine Abuse Research Center, Oregon Health and Science University, Portland, Oregon (A.J.)
| | - Richard B Mailman
- Jazz Pharmaceuticals, Palo Alto, California (M.G.B., D.L.H., L.P.C.); Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, Texas (M.J.F., M.B.G.); Departments of Pharmacology and Neurology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania (R.B.M.); University of Arkansas for Medical Sciences, Little Rock, Arkansas (L.P.C.); Research and Development Service, Veterans Affairs Portland Health Care System, Portland, Oregon (A.J.); and Departments of Psychiatry and Behavioral Neuroscience, and Methamphetamine Abuse Research Center, Oregon Health and Science University, Portland, Oregon (A.J.)
| | - Danielle L Hyman
- Jazz Pharmaceuticals, Palo Alto, California (M.G.B., D.L.H., L.P.C.); Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, Texas (M.J.F., M.B.G.); Departments of Pharmacology and Neurology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania (R.B.M.); University of Arkansas for Medical Sciences, Little Rock, Arkansas (L.P.C.); Research and Development Service, Veterans Affairs Portland Health Care System, Portland, Oregon (A.J.); and Departments of Psychiatry and Behavioral Neuroscience, and Methamphetamine Abuse Research Center, Oregon Health and Science University, Portland, Oregon (A.J.)
| | - Lawrence P Carter
- Jazz Pharmaceuticals, Palo Alto, California (M.G.B., D.L.H., L.P.C.); Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, Texas (M.J.F., M.B.G.); Departments of Pharmacology and Neurology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania (R.B.M.); University of Arkansas for Medical Sciences, Little Rock, Arkansas (L.P.C.); Research and Development Service, Veterans Affairs Portland Health Care System, Portland, Oregon (A.J.); and Departments of Psychiatry and Behavioral Neuroscience, and Methamphetamine Abuse Research Center, Oregon Health and Science University, Portland, Oregon (A.J.)
| | - Aaron Janowsky
- Jazz Pharmaceuticals, Palo Alto, California (M.G.B., D.L.H., L.P.C.); Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, Texas (M.J.F., M.B.G.); Departments of Pharmacology and Neurology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania (R.B.M.); University of Arkansas for Medical Sciences, Little Rock, Arkansas (L.P.C.); Research and Development Service, Veterans Affairs Portland Health Care System, Portland, Oregon (A.J.); and Departments of Psychiatry and Behavioral Neuroscience, and Methamphetamine Abuse Research Center, Oregon Health and Science University, Portland, Oregon (A.J.)
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5
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Rubio Morell B, Hernández Expósito S. Differential long-term medication impact on executive function and delay aversion in ADHD. APPLIED NEUROPSYCHOLOGY-CHILD 2017; 8:140-157. [DOI: 10.1080/21622965.2017.1407653] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Belen Rubio Morell
- Child Psychiatry Unit, Hospital Universitario de Canarias, La Laguna, Spain
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6
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Kirjavainen AK, Forsback S, López-Picón FR, Marjamäki P, Takkinen J, Haaparanta-Solin M, Peters D, Solin O. 18F-labeled norepinephrine transporter tracer [ 18F]NS12137: radiosynthesis and preclinical evaluation. Nucl Med Biol 2017; 56:39-46. [PMID: 29172120 DOI: 10.1016/j.nucmedbio.2017.10.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 10/11/2017] [Accepted: 10/16/2017] [Indexed: 01/16/2023]
Abstract
INTRODUCTION Several psychiatric and neurodegenerative diseases are associated with malfunction of brain norepinephrine transporter (NET). However, current clinical evaluations of NET function are limited by the lack of sufficiently sensitive methods of detection. To this end, we have synthesized exo-3-[(6-[18F]fluoro-2-pyridyl)oxy]-8-azabicyclo[3.2.1]-octane ([18F]NS12137) as a radiotracer for positron emission tomography (PET) and have demonstrated that it is highly specific for in vivo detection of NET-rich regions of rat brain tissue. METHODS We applied two methods of electrophilic, aromatic radiofluorination of the precursor molecule, exo-3-[(6-trimethylstannyl-2-pyridyl)oxy]-8-azabicyclo-[3.2.1]octane-8-carboxylate: (1) direct labeling with [18F]F2, and (2) labeling with [18F]Selectfluor, a derivative of [18F]F2, using post-target produced [18F]F2. The time-dependent distribution of [18F]NS12137 in brain tissue of healthy, adult Sprague-Dawley rats was determined by ex vivo autoradiography. The specificity of [18F]NS12137 binding was demonstrated on the basis of competitive binding by nisoxetine, a known NET antagonist of high specificity. RESULTS [18F]NS12137 was successfully synthesized with radiochemical yields of 3.9% ± 0.3% when labeled with [18F]F2 and 10.2% ± 2.7% when labeled with [18F]Selectfluor. The molar activity of radiotracer was 8.8 ± 0.7 GBq/μmol with [18F]F2 labeling and 6.9 ± 0.4 GBq/μmol with [18F]Selectfluor labeling at the end of synthesis of [18F]NS12137. Uptake of [18F]NS12137 in NET-rich areas in rat brain was demonstrated with the locus coeruleus (LCoe) having the highest regional uptake. Prior treatment of rats with nisoxetine showed no detectable [18F]NS12137 in the LCoe. Analyses of whole brain samples for radiometabolites showed only the parent compound [18F]NS12137. Uptake of 18F-radioactivity in bone increased with time. CONCLUSIONS The two electrophilic 18F-labeling methods proved to be suitable for synthesis of [18F]NS12137 with the [18F]Selectfluor method providing an approximate three-fold higher yield than the [18F]F2 method. As an electrostatically neutral radiotracer [18F]NS12137 crosses the blood-brain barrier and enabled specific labeling of NET-rich regions of rat brain tissue with the highest concentration in the LCoe.
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Affiliation(s)
- Anna K Kirjavainen
- Radiopharmaceutical Chemistry Laboratory, Turku PET Centre, University of Turku, Turku, Finland.
| | - Sarita Forsback
- Radiopharmaceutical Chemistry Laboratory, Turku PET Centre, University of Turku, Turku, Finland; Department of Chemistry, University of Turku, Turku, Finland
| | - Francisco R López-Picón
- Preclinical Imaging, Turku PET Centre, University of Turku, Turku, Finland; Medicity Research Laboratory, University of Turku, Turku, Finland
| | | | - Jatta Takkinen
- Preclinical Imaging, Turku PET Centre, University of Turku, Turku, Finland; Medicity Research Laboratory, University of Turku, Turku, Finland
| | - Merja Haaparanta-Solin
- Preclinical Imaging, Turku PET Centre, University of Turku, Turku, Finland; Medicity Research Laboratory, University of Turku, Turku, Finland
| | - Dan Peters
- DanPET AB, Malmö, Sweden; Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Olof Solin
- Radiopharmaceutical Chemistry Laboratory, Turku PET Centre, University of Turku, Turku, Finland; Department of Chemistry, University of Turku, Turku, Finland; Accelerator Laboratory, Åbo Akademi University, Turku, Finland
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7
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Shahzad D, Faisal M, Rauf A, Huang JH. Synthetic Story of a Blockbuster Drug: Reboxetine, a Potent Selective Norepinephrine Reuptake Inhibitor. Org Process Res Dev 2017. [DOI: 10.1021/acs.oprd.7b00265] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Danish Shahzad
- Department
of Chemistry, Quaid-i-Azam University, 45320 Islamabad, Pakistan
| | - Muhammad Faisal
- Department
of Chemistry, Quaid-i-Azam University, 45320 Islamabad, Pakistan
| | - Ameema Rauf
- Department
of Chemistry, University of Wah, Wah Cantt, Pakistan
| | - Jian-hua Huang
- School
of Pharmacy, Hunan University of Chinese Medicine, Changsha 410208, China
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Schulz KP, Bédard ACV, Fan J, Hildebrandt TB, Stein MA, Ivanov I, Halperin JM, Newcorn JH. Striatal Activation Predicts Differential Therapeutic Responses to Methylphenidate and Atomoxetine. J Am Acad Child Adolesc Psychiatry 2017. [PMID: 28647012 DOI: 10.1016/j.jaac.2017.04.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVE Methylphenidate has prominent effects in the dopamine-rich striatum that are absent for the selective norepinephrine transporter inhibitor atomoxetine. This study tested whether baseline striatal activation would predict differential response to the two medications in youth with attention-deficit/hyperactivity disorder (ADHD). METHOD A total of 36 youth with ADHD performed a Go/No-Go test during functional magnetic resonance imaging at baseline and were treated with methylphenidate and atomoxetine using a randomized cross-over design. Whole-brain task-related activation was regressed on clinical response. RESULTS Task-related activation in right caudate nucleus was predicted by an interaction of clinical responses to methylphenidate and atomoxetine (F1,30 = 17.00; p < .001). Elevated caudate activation was associated with robust improvement for methylphenidate and little improvement for atomoxetine. The rate of robust response was higher for methylphenidate than for atomoxetine in youth with high (94.4% vs. 38.8%; p = .003; number needed to treat = 2, 95% CI = 1.31-3.73) but not low (33.3% vs. 50.0%; p = .375) caudate activation. Furthermore, response to atomoxetine predicted motor cortex activation (F1,30 = 14.99; p < .001). CONCLUSION Enhanced caudate activation for response inhibition may be a candidate biomarker of superior response to methylphenidate over atomoxetine in youth with ADHD, purportedly reflecting the dopaminergic effects of methylphenidate but not atomoxetine in the striatum, whereas motor cortex activation may predict response to atomoxetine. These data do not yet translate directly to the clinical setting, but the approach is potentially important for informing future research and illustrates that it may be possible to predict differential treatment response using a biomarker-driven approach. CLINICAL TRIAL REGISTRATION INFORMATION Stimulant Versus Nonstimulant Medication for Attention Deficit Hyperactivity Disorder in Children; https://clinicaltrials.gov/; NCT00183391.
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Affiliation(s)
| | | | - Jin Fan
- Icahn School of Medicine at Mount Sinai, New York; Queens College of the City University of New York
| | | | | | | | - Jeffrey M Halperin
- Icahn School of Medicine at Mount Sinai, New York; Queens College of the City University of New York
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9
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Benn A, Robinson ESJ. Differential roles for cortical versus sub-cortical noradrenaline and modulation of impulsivity in the rat. Psychopharmacology (Berl) 2017; 234:255-266. [PMID: 27744551 PMCID: PMC5203835 DOI: 10.1007/s00213-016-4458-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 10/03/2016] [Indexed: 12/31/2022]
Abstract
RATIONALE Atomoxetine is a noradrenaline re-uptake inhibitor licensed for the treatment of adult and childhood attention deficit hyperactivity disorder. Although atomoxetine has established efficacy, the mechanisms which mediate its effects are not well understood. OBJECTIVES In this study, we investigated the role of cortical versus sub-cortical noradrenaline by using focal dopamine beta hydroxylase-saporin-induced lesions, to the prefrontal cortex (n = 16) or nucleus accumbens shell (n = 18). METHODS Healthy animals were tested by using the forced-choice serial reaction time task to assess the impact of the lesion on baseline performance and the response to atomoxetine and the psychostimulant amphetamine. RESULTS We observed attenuation in the efficacy of atomoxetine in animals with lesions to the nucleus accumbens shell, but not the prefrontal cortex. Amphetamine-induced increases in premature responses were potentiated in animals with lesions to the prefrontal cortex, but not the nucleus accumbens shell. CONCLUSIONS These data suggest that noradrenaline in the nucleus accumbens shell plays an important role in the effects of atomoxetine. Under these conditions, prefrontal cortex noradrenaline did not appear to contribute to atomoxetine's effects suggesting a lack of cortical-mediated "top-down" modulation. Noradrenaline in the prefrontal cortex appears to contribute to the modulation of impulsive responding in amphetamine-treated animals, with a loss of noradrenaline associated with potentiation of its effects. These data demonstrate a potential dissociation between cortical and sub-cortical noradrenergic mechanisms and impulse control in terms of the actions of atomoxetine and amphetamine.
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Affiliation(s)
- Abigail Benn
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Biomedical Sciences Building, University Walk, Bristol, BS8 1TD, UK
| | - Emma S J Robinson
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Biomedical Sciences Building, University Walk, Bristol, BS8 1TD, UK.
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10
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Dihydroxyphenylglycol as a Biomarker of Norepinephrine Transporter Inhibition by Atomoxetine: Human Model to Assess Central and Peripheral Effects of Dosing. J Clin Psychopharmacol 2016; 36:675-683. [PMID: 27755221 DOI: 10.1097/jcp.0000000000000611] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
To assess the primary metabolite of norepinephrine, 3,4-dihydroxyphenylglycol (DHPG), as a sensitive biomarker for norepinephrine transporter (NET) function and the relationship of DHPG measured peripherally and centrally, NET was antagonized with 80 mg/d atomoxetine for 18 days. Twelve healthy subjects were treated with atomoxetine in an open-label, multiple-dose exploratory study. Plasma atomoxetine reached steady state by day 6, and the pharmacokinetic results demonstrated availability of atomoxetine to the central nervous system. The cerebrospinal fluid (CSF)/plasma ratios of atomoxetine based on area under concentration-time curve from 0 to 12 hours postdose (AUC0-12), maximum concentration (Cmax), and predose were 0.3%, 0.2%, and 11%, respectively. Plasma from atomoxetine-treated subjects (ex vivo) significantly inhibited radioligand binding to human NET (P < 0.001) only 1 hour after dosing. Plasma DHPG and DHPG/norepinephrine (ratio) during repeated posture tests were reduced significantly (P < 0.001) on day 5 and stayed significantly reduced up to 1 day after treatment. In CSF, both DHPG and the ratio were significantly reduced (P < 0.001) on day 18. Urine results showed significant decreases for both DHPG and the ratio (P = 0.010 to P < 0.001). Brain-derived neurotrophic factor in CSF was lesser than the limits of detection. The findings suggest that NET blockade can be assessed with DHPG concentration or with the ratio in plasma, CSF, and urine. The data suggest that DHPG is a useful biomarker to proactively assess the pharmacological activity of compounds intended to inhibit NET activity within the brain. The study shows that CSF is a medium for early identification and quantification of biomarkers useful in assessing novel neuroscience targets.
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Abstract
Children/adolescents with attention-deficit/hyperactivity disorder (ADHD) may have a poor or inadequate response to psychostimulants or be unable to tolerate their side-effects; furthermore, stimulants may be inappropriate because of co-existing conditions. Only one non-stimulant ADHD pharmacotherapy, the noradrenaline transporter inhibitor atomoxetine, is currently approved for use in Europe. We review recent advances in understanding of the pathophysiology of ADHD with a focus on the roles of catecholamine receptors in context of the α2A-adrenergic receptor agonist guanfacine extended release (GXR), a new non-stimulant treatment option in Europe. Neuroimaging studies of children/adolescents with ADHD show impaired brain maturation, and structural and functional anomalies in brain regions and networks. Neurobiological studies in ADHD and medication response patterns support involvement of monoaminergic neurotransmitters (primarily dopamine and noradrenaline). Guanfacine is a selective α2A-adrenergic receptor agonist that has been shown to improve prefrontal cortical cognitive function, including working memory. The hypothesized mode of action of guanfacine centres on direct stimulation of post-synaptic α2A-adrenergic receptors to enhance noradrenaline neurotransmission. Preclinical data suggest that guanfacine also influences dendritic spine growth and maturation. Clinical trials have demonstrated the efficacy of GXR in ADHD, and it is approved as monotherapy or adjunctive therapy to stimulants in Canada and the USA (for children and adolescents). GXR was approved recently in Europe for the treatment of ADHD in children and adolescents for whom stimulants are not suitable, not tolerated or have been shown to be ineffective. GXR may provide particular benefit for children/adolescents who have specific co-morbidities such as chronic tic disorders or oppositional defiant disorder (or oppositional symptoms) that have failed to respond to first-line treatment options.
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12
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Mandeville JB, Sander CYM, Wey HY, Hooker JM, Hansen HD, Svarer C, Knudsen GM, Rosen BR. A regularized full reference tissue model for PET neuroreceptor mapping. Neuroimage 2016; 139:405-414. [PMID: 27364474 DOI: 10.1016/j.neuroimage.2016.06.044] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Revised: 05/26/2016] [Accepted: 06/24/2016] [Indexed: 12/27/2022] Open
Abstract
The full reference tissue model (FRTM) is a PET analysis framework that includes both free and specifically bound compartments within tissues, together with rate constants defining association and dissociation from the specifically bound compartment. The simplified reference tissue model (SRTM) assumes instantaneous exchange between tissue compartments, and this "1-tissue" approximation reduces the number of parameters and enables more robust mapping of non-displaceable binding potentials. Simulations based upon FRTM have shown that SRTM exhibits biases that are spatially dependent, because biases depend upon binding potentials. In this work, we describe a regularized model (rFRTM) that employs a global estimate of the dissociation rate constant from the specifically bound compartment (k4). The model provides an internal calibration for optimizing k4 through the reference-region outflow rate k2', a model parameter that should be a global constant but varies regionally in SRTM. Estimates of k4 by rFRTM are presented for four PET radioligands. We show that SRTM introduces bias in parameter estimates by assuming an infinite value for k4, and that rFRTM ameliorates bias with an appropriate choice of k4. Theoretical considerations and simulations demonstrate that rFRTM reduces bias in non-displaceable binding potentials. A two-parameter reduction of the model (rFRTM2) provides robust mapping at a voxel-wise level. With a structure similar to SRTM, the model is easily implemented and can be applied as a PET reference region analysis that reduces parameter bias without substantially altering parameter variance.
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Affiliation(s)
- Joseph B Mandeville
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States.
| | - Christin Y M Sander
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States
| | - Hsiao-Ying Wey
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States
| | - Jacob M Hooker
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States
| | - Hanne D Hansen
- Neurobiology Research Unit, Rigshospitalet and University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Claus Svarer
- Neurobiology Research Unit, Rigshospitalet and University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Gitte M Knudsen
- Neurobiology Research Unit, Rigshospitalet and University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Bruce R Rosen
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States
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[(18)F]FMeNER-D2: A systematic in vitro analysis of radio-metabolism. Nucl Med Biol 2016; 43:490-5. [PMID: 27236284 DOI: 10.1016/j.nucmedbio.2016.05.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 05/06/2016] [Accepted: 05/10/2016] [Indexed: 11/23/2022]
Abstract
INTRODUCTION The norepinephrine transporter (NET) presents an important target for therapy and diagnosis of ADHD and other neurodegenerative and psychiatric diseases. Thus, PET is the diagnostic method of choice, using radiolabeled NET-ligands derived from reboxetine. So far, [(18)F]FMeNER-D2 showed best pharmacokinetic and -dynamic properties. However, the disadvantage of reboxetine derived PET tracers is their high metabolic cleavage-resulting in impeding signals in the PET scans, which hamper a proper quantification of the NET in cortical areas. METHODS Metabolic stability testing was performed in vitro using a plethora of human and murine enzymes. RESULTS No metabolism was observed using monoamine oxidase A and B or catechol-O-methyl transferase. Incubation of [(18)F]FMeNER-D2 with CYP450-enzymes, predominantly located in the liver, led to a significant and fast metabolism of the tracer. Moreover, the arising three radiometabolites were found to be more polar than [(18)F]FMeNER-D2. Surprisingly, definitely no formation of free [(18)F]fluoride was observed. CONCLUSION According to our in vitro data, the interfering uptake in cortical regions might be attributed to these emerging radiometabolites but does not reflect bonding in bone due to defluorination. Further research on these radiometabolites is necessary to elucidate the in vivo situation. This might include an analysis of human blood samples after injection of [(18)F]FMeNER-D2, to enable a better correction of the PET-input function.
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Stehouwer JS, Goodman MM. Fluorine-18 Radiolabeled PET Tracers for Imaging Monoamine Transporters: Dopamine, Serotonin, and Norepinephrine. PET Clin 2016; 4:101-28. [PMID: 20216936 DOI: 10.1016/j.cpet.2009.05.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
This review focuses on the development of fluorine-18 radiolabeled PET tracers for imaging the dopamine transporter (DAT), serotonin transporter (SERT), and norepinephrine transporter (NET). All successful DAT PET tracers reported to date are members of the 3β-phenyl tropane class and are synthesized from cocaine. Currently available carbon-11 SERT PET tracers come from both the diphenylsulfide and 3β-phenyl nortropane class, but so far only the nortropanes have found success with fluorine-18 derivatives. NET imaging has so far employed carbon-11 and fluorine-18 derivatives of reboxetine but due to defluorination of the fluorine-18 derivatives further research is still necessary.
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15
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Eslami Amirabadi MR, Davari-Ashtiani R, Khademi M, RajeziEsfahani S, Emamalizadeh B, Movafagh A, Arabgol F, Sadr S, Darvish H, Razjouyan K. No Evidence for Association Between Norepinephrine Transporter-3081 (A/T) Polymorphism and Attention Deficit Hyperactivity Disorder in Iranian Population. IRANIAN RED CRESCENT MEDICAL JOURNAL 2015; 17:e22996. [PMID: 26421175 PMCID: PMC4584105 DOI: 10.5812/ircmj.229961v2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Revised: 09/09/2014] [Accepted: 11/09/2014] [Indexed: 11/23/2022]
Abstract
Background: Attention Deficit Hyperactivity Disorder (ADHD) can lead to drastic problems for the patient and its worldwide prevalence is 5%-12%. It also has many comorbidities with other disorders, and the genetic contribution seems the most significant cause. Objectives: The current study was conducted to investigate the association between norepinephrine transporter-3081 (A/T) polymorphisms and ADHD in Iranian population. Patients and Methods: Participants were chosen from children and adolescents diagnosed with ADHD referred to Imam Hoseyn Hospital. A child and adolescent psychiatrist confirmed the diagnosis using the Kiddie-Sads-Present and Lifetime Version (K-SADS-PL) semi-structural interview. The control group was from pupils of schools in Tehran (capital city of Iran) who had no history or presence of psychiatric and medical complications. Also, a child and adolescent psychiatrist confirmed their health using the K-SADS-PL semi-structural interview. Genetic examinations were DNA distraction, Polymerase Chain Reaction (PCR), and Restricted Fragment Length Polymorphism (RFLP), which were conducted according to standard protocols. The statistical analysis was performed using chi-square and Fisher's exact test in SPSS version 21. Results: The percentages of ADHD subtypes for combined, inattentive, and hyperactive/impulsive were 72.2%, 17.2%, and 11.9%, respectively. There was no significant association between norepinephrine transporter polymorphism and ADHD (P = 0.81). Moreover, no significant relationship was found between gender [male (P = 0.92) and female (P = 0.63)] and polymorphism. No significant association was found between subtypes of ADHD [combined (P = 0.46), inattentive (P = 0.41), hyperactive/impulsive (P = 0.32)] and polymorphism SCL6A2. This lack of association can also be seen in gender in every subtype. Conclusions: The results of the study show no significant association between norepinephrine transporter polymorphism SCL6A2 and ADHD.
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Affiliation(s)
| | - Rozita Davari-Ashtiani
- Department of Psychiatry, Imam Hosein Hospital, Shahid Beheshti University of Medical Sciences, Tehran, IR Iran
| | - Mojgan Khademi
- Department of Psychiatry, Imam Hosein Hospital, Shahid Beheshti University of Medical Sciences, Tehran, IR Iran
| | - Sepideh RajeziEsfahani
- Behavioral Sciences Research Center, Shahid Beheshti University of Medical Sciences, Tehran, IR Iran
| | - Babak Emamalizadeh
- Department of Medical Genetics, Shahid Beheshti University of Medical Sciences, Tehran, IR Iran
| | - Abolfazl Movafagh
- Department of Medical Genetics, Shahid Beheshti University of Medical Sciences, Tehran, IR Iran
| | - Fariba Arabgol
- Department of Psychiatry, Imam Hosein Hospital, Shahid Beheshti University of Medical Sciences, Tehran, IR Iran
| | - Said Sadr
- Department of Psychiatry, Imam Hosein Hospital, Shahid Beheshti University of Medical Sciences, Tehran, IR Iran
| | - Hossein Darvish
- Department of Medical Genetics, Shahid Beheshti University of Medical Sciences, Tehran, IR Iran
- Corresponding Authors: Katayoon Razjoyan, Department of Psychiatry, Imam Hosein Hospital, Shahid Beheshti University of Medical Sciences, Tehran, IR Iran. Tel/Fax: +98-2123872572, E-mail: ; Hossein Darvish, Department of Medical Genetics, Shahid Beheshti University of Medical Sciences, Tehran, IR Iran. Tel/Fax: +98-2123872572, E-mail:
| | - Katayoon Razjouyan
- Department of Psychiatry, Imam Hosein Hospital, Shahid Beheshti University of Medical Sciences, Tehran, IR Iran
- Corresponding Authors: Katayoon Razjoyan, Department of Psychiatry, Imam Hosein Hospital, Shahid Beheshti University of Medical Sciences, Tehran, IR Iran. Tel/Fax: +98-2123872572, E-mail: ; Hossein Darvish, Department of Medical Genetics, Shahid Beheshti University of Medical Sciences, Tehran, IR Iran. Tel/Fax: +98-2123872572, E-mail:
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16
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Lin HY, Gau SSF. Atomoxetine Treatment Strengthens an Anti-Correlated Relationship between Functional Brain Networks in Medication-Naïve Adults with Attention-Deficit Hyperactivity Disorder: A Randomized Double-Blind Placebo-Controlled Clinical Trial. Int J Neuropsychopharmacol 2015; 19:pyv094. [PMID: 26377368 PMCID: PMC4815465 DOI: 10.1093/ijnp/pyv094] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2015] [Accepted: 08/14/2015] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Although atomoxetine demonstrates efficacy in individuals with attention-deficit hyperactivity disorder, its treatment effects on brain resting-state functional connectivity remain unknown. Therefore, we aimed to investigate major brain functional networks in medication-naïve adults with attention-deficit hyperactivity disorder and the efficacy of atomoxetine treatment on resting-state functional connectivity. METHODS After collecting baseline resting-state functional MRI scans from 24 adults with attention-deficit hyperactivity disorder (aged 18-52 years) and 24 healthy controls (matched in demographic characteristics), the participants with attention-deficit hyperactivity disorder were randomly assigned to atomoxetine (n=12) and placebo (n=12) arms in an 8-week, double-blind, placebo-controlled trial. The primary outcome was functional connectivity assessed by a resting-state functional MRI. Seed-based functional connectivity was calculated and compared for the affective, attention, default, and cognitive control networks. RESULTS At baseline, we found atypical cross talk between the default, cognitive control, and dorsal attention networks and hypoconnectivity within the dorsal attention and default networks in adults with attention-deficit hyperactivity disorder. Our first-ever placebo-controlled clinical trial incorporating resting-state functional MRI showed that treatment with atomoxetine strengthened an anticorrelated relationship between the default and task-positive networks and modulated all major brain networks. The strengthened anticorrelations were associated with improving clinical symptoms in the atomoxetine-treated adults. CONCLUSIONS Our results support the idea that atypical default mode network task-positive network interaction plays an important role in the pathophysiology of adult attention-deficit hyperactivity disorder. Strengthening this atypical relationship following atomoxetine treatment suggests an important pathway to treat attention-deficit hyperactivity disorder.
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Affiliation(s)
| | - Susan Shur-Fen Gau
- Department of Psychiatry, National Taiwan University Hospital and College of Medicine, Taipei, Taiwan (Drs Lin and Gau); Graduate Institute of Brain and Mind Sciences, and Graduate Institute of Clinical Medicine, National Taiwan University College of Medicine, Taipei, Taiwan (Dr Gau).
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17
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Kielbasa W, Lobo E. Pharmacodynamics of norepinephrine reuptake inhibition: Modeling the peripheral and central effects of atomoxetine, duloxetine, and edivoxetine on the biomarker 3,4-dihydroxyphenylglycol in humans. J Clin Pharmacol 2015; 55:1422-31. [DOI: 10.1002/jcph.551] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 05/18/2015] [Indexed: 12/20/2022]
Affiliation(s)
- William Kielbasa
- Eli Lilly and Company; Lilly Research Laboratories; Indianapolis IN USA
| | - Evelyn Lobo
- Former employee of Eli Lilly and Company; no current affiliation
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18
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Hohmann S, Hohm E, Treutlein J, Blomeyer D, Jennen-Steinmetz C, Schmidt MH, Esser G, Banaschewski T, Brandeis D, Laucht M. Association of norepinephrine transporter (NET, SLC6A2) genotype with ADHD-related phenotypes: findings of a longitudinal study from birth to adolescence. Psychiatry Res 2015; 226:425-33. [PMID: 25724484 DOI: 10.1016/j.psychres.2014.12.029] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Revised: 12/16/2014] [Accepted: 12/18/2014] [Indexed: 10/24/2022]
Abstract
Variation in the gene encoding for the norepinephrine transporter (NET, SLC6A2) has repeatedly been linked with ADHD, although there is some inconsistency regarding the association with specific genes. The variants for which most consistent association has been found are the NET variants rs3785157 and rs28386840. Here, we tested for their association with ADHD diagnosis and ADHD-related phenotypes during development in a longitudinal German community sample. Children were followed from age 4 to age 15, using diagnostic interviews to assess ADHD. Between the ages of 8 and 15 years, the Child Behavior Checklist (CBCL) was administered to the primary caregivers. The continuous performance task (CPT) was performed at age 15. Controlling for possible confounders, we found that homozygous carriers of the major A allele of the functional promoter variant rs28386840 displayed a higher rate of ADHD lifetime diagnosis. Moreover, homozygous carriers of the minor T allele of rs3785157 were more likely to develop ADHD and showed higher scores on the CBCL externalizing behavior scales. Additionally, we found that individuals heterozygous for rs3785157 made fewer omission errors in the CPT than homozygotes. This is the first longitudinal study to report associations between specific NET variants and ADHD-related phenotypes during the course of development.
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Affiliation(s)
- Sarah Hohmann
- Department of Child and Adolescent Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim/Heidelberg University, Mannheim, Germany
| | - Erika Hohm
- Department of Child and Adolescent Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim/Heidelberg University, Mannheim, Germany
| | - Jens Treutlein
- Molecular Genetics Laboratory, Central Institute of Mental Health, Medical Faculty Mannheim/Heidelberg University, Mannheim, Germany
| | - Dorothea Blomeyer
- Department of Child and Adolescent Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim/Heidelberg University, Mannheim, Germany
| | - Christine Jennen-Steinmetz
- Department of Biostatistics, Central Institute of Mental Health, Medical Faculty Mannheim/Heidelberg University, Mannheim, Germany
| | - Martin H Schmidt
- Department of Child and Adolescent Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim/Heidelberg University, Mannheim, Germany
| | - Günter Esser
- Department of Psychology, University of Potsdam, Potsdam, Germany
| | - Tobias Banaschewski
- Department of Child and Adolescent Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim/Heidelberg University, Mannheim, Germany
| | - Daniel Brandeis
- Department of Child and Adolescent Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim/Heidelberg University, Mannheim, Germany; Department of Child and Adolescent Psychiatry, University of Zurich, Zurich, Switzerland
| | - Manfred Laucht
- Department of Child and Adolescent Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim/Heidelberg University, Mannheim, Germany; Department of Psychology, University of Potsdam, Potsdam, Germany.
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Finnema SJ, Hughes ZA, Haaparanta-Solin M, Stepanov V, Nakao R, Varnäs K, Varrone A, Arponen E, Marjamäki P, Pohjanoksa K, Vuorilehto L, Babalola PA, Solin O, Grimwood S, Sallinen J, Farde L, Scheinin M, Halldin C. Amphetamine decreases α2C-adrenoceptor binding of [11C]ORM-13070: a PET study in the primate brain. Int J Neuropsychopharmacol 2015; 18:pyu081. [PMID: 25522417 PMCID: PMC4360244 DOI: 10.1093/ijnp/pyu081] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND The neurotransmitter norepinephrine has been implicated in psychiatric and neurodegenerative disorders. Examination of synaptic norepinephrine concentrations in the living brain may be possible with positron emission tomography (PET), but has been hampered by the lack of suitable radioligands. METHODS We explored the use of the novel α2C-adrenoceptor antagonist PET tracer [(11)C]ORM-13070 for measurement of amphetamine-induced changes in synaptic norepinephrine. The effect of amphetamine on [(11)C]ORM-13070 binding was evaluated ex vivo in rat brain sections and in vivo with PET imaging in monkeys. RESULTS Microdialysis experiments confirmed amphetamine-induced elevations in rat striatal norepinephrine and dopamine concentrations. Regional [(11)C]ORM-13070 receptor binding was high in the striatum and low in the cerebellum. After injection of [(11)C]ORM-13070 in rats, mean striatal specific binding ratios, determined using cerebellum as a reference region, were 1.4±0.3 after vehicle pretreatment and 1.2±0.2 after amphetamine administration (0.3mg/kg, subcutaneous). Injection of [(11)C]ORM-13070 in non-human primates resulted in mean striatal binding potential (BP ND) estimates of 0.65±0.12 at baseline. Intravenous administration of amphetamine (0.5 and 1.0mg/kg, i.v.) reduced BP ND values by 31-50%. Amphetamine (0.3mg/kg, subcutaneous) increased extracellular norepinephrine (by 400%) and dopamine (by 270%) in rat striata. CONCLUSIONS Together, these results indicate that [(11)C]ORM-13070 may be a useful tool for evaluation of synaptic norepinephrine concentrations in vivo. Future studies are required to further understand a potential contribution of dopamine to the amphetamine-induced effect.
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Affiliation(s)
- Sjoerd J Finnema
- Karolinska Institutet, Department of Clinical Neuroscience, Center for Psychiatric Research, Stockholm, Sweden (Drs Finnema, Stepanov, Nakao, Varnäs, Varrone, Farde, and Halldin); Pfizer, Neuroscience Research Unit, Cambridge, MA (Drs Hughes, Babalola, and Grimwood); University of Turku, Turku PET Centre, Turku, Finland (Drs Haaparanta-Solin, Arponen, Marjamäki, and Solin); University of Turku, Department of Pharmacology, Drug Development and Therapeutics, and Turku University Hospital, Unit of Clinical Pharmacology, Turku, Finland (Drs Pohjanoksa, Vuorilehto, and Scheinin); Orion Corporation, Orion Pharma, Research and Development, Turku, Finland (Dr Sallinen); AstraZeneca, Translational Science Center at Karolinska Institutet, Stockholm, Sweden (Dr Farde)
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Araki A, Ikegami M, Okayama A, Matsumoto N, Takahashi S, Azuma H, Takahashi M. Improved prefrontal activity in AD/HD children treated with atomoxetine: a NIRS study. Brain Dev 2015; 37:76-87. [PMID: 24767548 DOI: 10.1016/j.braindev.2014.03.011] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Revised: 02/13/2014] [Accepted: 03/21/2014] [Indexed: 10/25/2022]
Abstract
BACKGROUND/AIMS Atomoxetine (ATX), a selective norepinephrine reuptake inhibitor, is the first approved non-stimulant drug for treatment of attention deficit/hyperactivity disorder (AD/HD). The present study examined the effects of long-term treatment with ATX on prefrontal hemodynamic activity in AD/HD children during a continuous performance task (CPT) using near-infrared spectroscopy (NIRS). METHODS Prefrontal hemodynamic activity was measured in 12 children with AD/HD during experimental sessions conducted before and 6 months or more after starting ATX treatment. The average maintenance dose of ATX was 1.6 mg/kg/day. Fourteen age-matched typically developing children participated as a control group. RESULTS In the control group, the CPT induced a significant increase in oxygenated hemoglobin (oxy-Hb) concentration in the bilateral dorsolateral prefrontal cortex (DLPFC). In the AD/HD group in the pre-ATX condition, the CPT did not induce a significant increase in oxy-Hb concentration in any of the NIRS channels, but induced a significant decrease in oxy-Hb concentration in the left ventrolateral prefrontal cortex (VLPFC). In the AD/HD group in the post-ATX condition, significant activation was observed in the right DLPFC and the decrease in oxy-Hb concentration in the left VLPFC disappeared. CONCLUSIONS These results suggest that long-term treatment with ATX improved prefrontal hemodynamic activity in AD/HD children, and NIRS may be useful for assessment of the prefrontal hemodynamic response to ATX treatment.
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Affiliation(s)
- Akiko Araki
- Department of Pediatrics, Asahikawa Medical University, Japan; Medical Research Center for Children's Development, Asahikawa Medical University, Japan
| | | | - Akie Okayama
- Department of Pediatrics, Asahikawa Medical University, Japan; Medical Research Center for Children's Development, Asahikawa Medical University, Japan
| | - Naoya Matsumoto
- Department of Pediatrics, Asahikawa Medical University, Japan
| | | | - Hiroshi Azuma
- Department of Pediatrics, Asahikawa Medical University, Japan; Medical Research Center for Children's Development, Asahikawa Medical University, Japan
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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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Norepinephrine transporter occupancy by nortriptyline in patients with depression: a positron emission tomography study with (S,S)-[¹⁸F]FMeNER-D₂. Int J Neuropsychopharmacol 2014; 17:553-60. [PMID: 24345533 DOI: 10.1017/s1461145713001521] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Norepinephrine transporter (NET) plays important roles in the treatment of various neuropsychiatric disorders, such as depression and attention deficit hyperactivity disorder (ADHD). Nortriptyline is a NET-selective tricyclic antidepressant (TCAs) that has been widely used for the treatment of depression. Previous positron emission tomography (PET) studies have reported over 80% serotonin transporter occupancy with clinical doses of selective serotonin reuptake inhibitors (SSRIs), but there has been no report of NET occupancy in patients treated with relatively NET-selective antidepressants. In the present study, we used PET and (S,S)-[18¹⁸F]FMeNER-D₂ to investigate NET occupancies in the thalamus in 10 patients with major depressive disorder taking various doses of nortriptyline, who were considered to be responders to the treatment. Reference data for the calculation of occupancy were derived from age-matched healthy controls. The result showed approximately 50-70% NET occupancies in the brain as a result of the administration of 75-200 mg/d of nortriptyline. The estimated effective dose (ED₅₀) and concentration (EC₅₀) required to induce 50% occupancy was 65.9 mg/d and 79.8 ng/ml, respectively. Furthermore, as the minimum therapeutic level of plasma nortriptyline for the treatment of depression has been reported to be 70 ng/ml, our data indicate that this plasma nortriptyline concentration corresponds to approximately 50% NET occupancy measured with PET, suggesting that more than 50% of central NET occupancy would be appropriate for the nortriptyline treatment of patients with depression.
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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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Mereu M, Bonci A, Newman AH, Tanda G. The neurobiology of modafinil as an enhancer of cognitive performance and a potential treatment for substance use disorders. Psychopharmacology (Berl) 2013; 229:415-34. [PMID: 23934211 PMCID: PMC3800148 DOI: 10.1007/s00213-013-3232-4] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Accepted: 07/28/2013] [Indexed: 12/31/2022]
Abstract
RATIONALE AND OBJECTIVES Modafinil (MOD) and its R-enantiomer (R-MOD) are approved medications for narcolepsy and other sleep disorders. They have also been used, off-label, as cognitive enhancers in populations of patients with mental disorders, including substance abusers that demonstrate impaired cognitive function. A debated nonmedical use of MOD in healthy individuals to improve intellectual performance is raising questions about its potential abuse liability in this population. RESULTS AND CONCLUSIONS MOD has low micromolar affinity for the dopamine transporter (DAT). Inhibition of dopamine (DA) reuptake via the DAT explains the enhancement of DA levels in several brain areas, an effect shared with psychostimulants like cocaine, methylphenidate, and the amphetamines. However, its neurochemical effects and anatomical pattern of brain area activation differ from typical psychostimulants and are consistent with its beneficial effects on cognitive performance processes such as attention, learning, and memory. At variance with typical psychostimulants, MOD shows very low, if any, abuse liability, in spite of its use as a cognitive enhancer by otherwise healthy individuals. Finally, recent clinical studies have focused on the potential use of MOD as a medication for treatment of drug abuse, but have not shown consistent outcomes. However, positive trends in several result measures suggest that medications that improve cognitive function, like MOD or R-MOD, may be beneficial for the treatment of substance use disorders in certain patient populations.
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Affiliation(s)
- Maddalena Mereu
- Molecular Targets & Medication Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, DHHS; 251 Bayview Blvd., NIDA suite 200, Baltimore, MD, 21224
| | - Antonello Bonci
- Synaptic Plasticity Section, Cellular Neurobiology Research Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, DHHS; 251 Bayview Blvd., NIDA suite 200, Baltimore, MD, 21224
| | - Amy Hauck Newman
- Molecular Targets & Medication Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, DHHS; 251 Bayview Blvd., NIDA suite 200, Baltimore, MD, 21224
| | - Gianluigi Tanda
- Molecular Targets & Medication Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, DHHS; 251 Bayview Blvd., NIDA suite 200, Baltimore, MD, 21224
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SERT and NET occupancy by venlafaxine and milnacipran in nonhuman primates: a PET study. Psychopharmacology (Berl) 2013; 226:147-53. [PMID: 23090625 DOI: 10.1007/s00213-012-2901-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Accepted: 09/27/2012] [Indexed: 10/27/2022]
Abstract
INTRODUCTION Serotonin and norepinephrine reuptake inhibitors (SNRIs) are antidepressants which have high affinity to both serotonin transporter (SERT) and norepinephrine transporter (NET). In studies in vitro, SNRIs have been reported to show a large variability in the affinity ratio between SERT and NET. For instance, the reported affinity ratio is about 30 for venlafaxine and 1.6 for milnacipran. In this study in nonhuman primates, we aimed to investigate the relationship between SERT and NET affinity by measuring the in vivo occupancy at both transporters of venlafaxine and milnacipran. METHODS PET measurements with [(11)C]MADAM and [(18)F]FMeNER-D(2) were performed in two female cynomolgus monkeys at baseline and after pretreatment with venlafaxine and milnacipran, respectively. Relationships between dose, plasma concentration, and transporter occupancy were evaluated by saturation analysis using a hyperbolic function. Binding affinity (Kd(plasma)) was expressed by the dose or plasma concentration at which 50 % of the transporter was occupied. RESULTS SERT and NET occupancy by venlafaxine and milnacipran increased in a dose and plasma concentration-dependent manner. The Kd(plasma) ratio of SERT to NET was 1.9 for venlafaxine and 0.6 for milnacipran. CONCLUSIONS In this nonhuman primate PET study, the affinity in vivo for SERT and NET, respectively, was shown to be at a similar level for venlafaxine and milnacipran. Both drugs were found to produce balanced inhibition of SERT and NET binding. This observation is not consistent with previous in vitro binding data and illustrates the need to characterize antidepressants at in vivo condition.
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Bush G, Holmes J, Shin LM, Surman C, Makris N, Mick E, Seidman LJ, Biederman J. Atomoxetine increases fronto-parietal functional MRI activation in attention-deficit/hyperactivity disorder: a pilot study. Psychiatry Res 2013; 211:88-91. [PMID: 23146254 PMCID: PMC3557757 DOI: 10.1016/j.pscychresns.2012.09.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Revised: 08/22/2012] [Accepted: 09/16/2012] [Indexed: 11/19/2022]
Abstract
We hypothesized that atomoxetine (ATMX) would produce similar brain effects in attention-deficit/hyperactivity disorder (ADHD) as those of methylphenidate (MPH). Eleven ADHD adults performed the Multi-Source Interference Task (MSIT) during functional magnetic resonance imaging (fMRI) at baseline and after 6 weeks of ATMX treatment. ATMX was associated with increased fMRI activation of dorsolateral prefrontal cortex, parietal cortex and cerebellum but not dorsal anterior midcingulate cortex (daMCC). These results suggest that ATMX and MPH have similar but not identical brain effects.
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Affiliation(s)
- George Bush
- Harvard Medical School, Department of Psychiatry, Boston, MA 02114, USA
- Psychiatric Neuroscience Division, Massachusetts General Hospital Department of Psychiatry, Boston, MA 02114, USA
- MGH/MIT/HMS Athinoula A. Martinos Center for Functional and Structural Biomedical Imaging (Massachusetts Institute of Technology, Harvard Medical School and Massachusetts General Hospital), Charlestown, MA 02129, USA
- Massachusetts General Hospital, Clinical and Research Program in Pediatric Psychopharmacology, Boston, MA 02114, USA
| | - Jennifer Holmes
- Psychiatric Neuroscience Division, Massachusetts General Hospital Department of Psychiatry, Boston, MA 02114, USA
| | - Lisa M. Shin
- Psychiatric Neuroscience Division, Massachusetts General Hospital Department of Psychiatry, Boston, MA 02114, USA
- Department of Psychology, Tufts University, Medford, MA, USA
| | - Craig Surman
- Harvard Medical School, Department of Psychiatry, Boston, MA 02114, USA
- Massachusetts General Hospital, Clinical and Research Program in Pediatric Psychopharmacology, Boston, MA 02114, USA
| | - Nikos Makris
- Massachusetts General Hospital, Clinical and Research Program in Pediatric Psychopharmacology, Boston, MA 02114, USA
- Harvard Medical School Departments of Neurology and Radiology Services, Center for Morphometric Analysis, Massachusetts General Hospital, Boston, MA 02129, USA
| | - Eric Mick
- Harvard Medical School, Department of Psychiatry, Boston, MA 02114, USA
- Massachusetts General Hospital, Clinical and Research Program in Pediatric Psychopharmacology, Boston, MA 02114, USA
| | - Larry J. Seidman
- Harvard Medical School, Department of Psychiatry, Boston, MA 02114, USA
- Massachusetts General Hospital, Clinical and Research Program in Pediatric Psychopharmacology, Boston, MA 02114, USA
- Harvard Medical School, Department of Psychiatry, Massachusetts Mental Health Center Public Psychiatry Division, Beth Israel Deaconess Medical Center, Boston, MA 02115, USA
| | - Joseph Biederman
- Harvard Medical School, Department of Psychiatry, Boston, MA 02114, USA
- Massachusetts General Hospital, Clinical and Research Program in Pediatric Psychopharmacology, Boston, MA 02114, USA
- For correspondence: Joseph Biederman, M.D., Chief, Clinical and Research Program in Pediatric Psychopharmacology and Adult ADHD at Massachusetts General Hospital, Professor of Psychiatry, Harvard Medical School, Phone: (617) 726-1743, Fax: (617) 724-3742,
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Tavares AADS, Barret O, Batis J, Alagille D, Koren A, Papin C, Kudej G, Nice K, Kordower JH, Cosgrove KP, Kloczynski T, Brenner E, Seibyl J, Tamagnan G. Kinetic modeling and occupancy measures of the norepinephrine transporters in baboons using single photon emission computed tomography with (123)I-INER. Synapse 2012; 67:30-41. [PMID: 23042643 DOI: 10.1002/syn.21613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Accepted: 10/01/2012] [Indexed: 11/11/2022]
Abstract
This study aims to investigate the pharmacokinetics of a recently developed radiotracer for imaging of the norepinephrine transporter (NET) in baboon brain, (123)I-INER, using single photon emission computed tomography (SPECT). In addition, it also aims to determine NET occupancy by atomoxetine and reboxetine, two selective norepinephrine reuptake inhibitors, using (123)I-INER in baboons. Baseline and preblocking studies with a high dose of atomoxetine (0.85 mg/kg) were conducted in three baboons using SPECT with (123)I-INER administered as a bolus. Kinetic modeling analysis was investigated for different models, namely invasive and reference tissue models. Bolus plus constant infusion experiments with displacement at equilibrium using six different doses of atomoxetine (0.03-0.85 mg/kg) and four different doses of reboxetine (0.5-3.0 mg/kg) were carried out in several baboons to obtain occupancy measurements as a function of dose for the two NET selective drugs. Results showed that reference tissue models can be used to estimate binding potential values and occupancy measures of (123)I-INER in different brain regions. In addition, the apparent volume of distribution was estimated by dividing concentration in tissue by the concentration in blood at 3 hours postinjection. After administration of atomoxetine or reboxetine, a dose-dependent occupancy was observed in brain regions known to contain high densities of NET. In conclusion, pharmacokinetic properties of (123) I-INER were successfully described, and obtained results may be used to simplify future data acquisition and image processing. Dose-dependent NET occupancy for two selective norepinephrine reuptake inhibitors was successfully measured in vivo in baboon brain using SPECT and (123) I-INER.
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Tavares AAS, Jobson NK, Dewar D, Sutherland A, Pimlott SL, Batis J, Barret O, Seibyl J, Tamagnan G. Iodine-123 labeled reboxetine analogues for imaging of noradrenaline transporter in brain using single photon emission computed tomography. Synapse 2012; 66:923-30. [PMID: 22807144 DOI: 10.1002/syn.21585] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Revised: 06/25/2012] [Accepted: 07/08/2012] [Indexed: 11/07/2022]
Abstract
Preliminary investigation of the radioiodinated (S,S)-reboxetine analogue, (123) I-INER, in baboons showed this tracer to have promise for imaging the noradrenaline transporter (NAT) using single photon emission computed tomography (SPECT). More recently, the radioiodinated (R,S)-stereoisomer of (123) I-INER, (123) I-NKJ64, has been synthesized and preliminary evaluation in rats has been reported. This article reports the brain distribution and pharmacokinetic properties of (123) I-NKJ64 in baboons and compares results with (123) I-INER data in the same species. SPECT studies were conducted in two ovariectomized adult female baboons using two different protocols: (1) bolus of (123) I-INER or (123) I-NKJ64; and (2) bolus plus constant infusion of (123) I-NKJ64 with reboxetine (2.0 mg/kg) administration at equilibrium. Following bolus injection, both radiotracers rapidly and avidly entered the baboon brain. The regional brain accumulation of (123) I-NKJ64 did not match the known distribution of NAT in baboon brain, contrasting with previous results obtained in rats. Conversely, the regional distribution of (123) I-INER was consistent with known distribution of NAT in baboon brain. No displacement of (123) I-NKJ64 was observed following administration of reboxetine. This contrasts with previous data obtained for (123) I-INER, where 60% of specific binding was displaced by a lower dose of reboxetine. These data suggest that (123) I-NKJ64 may lack affinity and selectivity for NAT in baboon brain and (123) I-INER is the most promising iodinated reboxetine analogue developed to date for in vivo imaging of NAT in brain using SPECT. This study highlights the importance of species differences during radiotracer development and the stereochemical configuration of analogues of reboxetine in vivo.
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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, United Kingdom.
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No evidence for association between a functional promoter variant of the Norepinephrine Transporter gene SLC6A2 and ADHD in a family-based sample. ACTA ACUST UNITED AC 2011; 3:285-9. [DOI: 10.1007/s12402-011-0060-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Accepted: 06/07/2011] [Indexed: 01/07/2023]
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Takano A, Nag S, Gulyás B, Halldin C, Farde L. NET occupancy by clomipramine and its active metabolite, desmethylclomipramine, in non-human primates in vivo. Psychopharmacology (Berl) 2011; 216:279-86. [PMID: 21336575 DOI: 10.1007/s00213-011-2212-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2010] [Accepted: 01/28/2011] [Indexed: 11/29/2022]
Abstract
RATIONALE Norepinephrine transporter (NET) is one of the key targets for antidepressants such as combined serotonin and norepinephrine reuptake inhibitors as well as some of the tricyclic antidepressants. Clomipramine, a tricyclic antidepressant, has been reported to have an active metabolite, desmethylclomipramine, which has high affinity for NET in vitro. However, the NET occupancy of clomipramine and desmethylclomipramine has not fully been evaluated in vivo. OBJECTIVES In this positron emission tomography (PET) study, we investigate NET occupancy by clomipramine and desmethylclomipramine, respectively, in non-human primates with a selective radioligand for NET, (S,S)-[(18)F]FMeNER-D(2). METHODS PET measurements were performed with (S,S)-[(18)F]FMeNER-D(2) at baseline and after the intravenous administration of clomipramine and desmethylclomipramine, respectively. NET binding was calculated with the simplified reference tissue model using the caudate as reference region. NET occupancy was calculated as the difference in NET binding between the baseline and pretreatment condition. The relationship between NET occupancy and dose/plasma concentration was evaluated using hyperbolic functions. RESULTS NET occupancy by both clomipramine and desmethylclomipramine increased in a dose and plasma concentration-dependent manner. The mean Kd values, expressed as the dose or plasma concentration at which 50% of NET was occupied, were 0.44 mg/kg and 24.5 ng/ml for clomipramine and 0.11 mg/kg and 4.4 ng/ml for desmethylclomipramine. CONCLUSIONS Not only desmethylclomipramine but also clomipramine was demonstrated to occupy NET in the non-human primate in vivo. It can thus be assumed that NET occupancy during clinical treatment with clomipramine is a combined effect of unchanged clomipramine and its main metabolite desmethylclomipramine.
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Affiliation(s)
- Akihiro Takano
- Department of Clinical Neuroscience, Psychiatry Section, Karolinska Institutet, 171 76, Stockholm, Sweden.
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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: 403] [Impact Index Per Article: 31.0] [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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Cognitive enhancers for the treatment of ADHD. Pharmacol Biochem Behav 2011; 99:262-74. [PMID: 21596055 DOI: 10.1016/j.pbb.2011.05.002] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Revised: 04/26/2011] [Accepted: 05/03/2011] [Indexed: 12/11/2022]
Abstract
Attention-deficit hyperactivity disorder (ADHD) is associated with multiple cognition-related phenotypic features in both children and adults. This review aims to clarify the role of cognition in ADHD and how prevailing treatments, which are often highly effective at reducing the clinical symptoms of the disorder, fare in modulating ADHD-related cognitive processes. First, we consider how the broad construct of cognition can be conceptualized in the context of ADHD. Second, we review the available evidence for how a range of both pharmacological and non-pharmacological interventions have fared with respect to enhancing cognition in individuals affected by this pervasive disorder. Findings from the literature suggest that the effects across a broad range of pharmacological and non-pharmacological interventions on the characteristic symptoms of ADHD can be distinguished from their effects on cognitive impairments. As such the direct clinical relevance of cognition enhancing effects of different interventions is somewhat limited. Recommendations for future research are discussed, including the identification of cognition-related endophenotypes, the refinement of the ADHD clinical phenotype, and studying the difference between acute and chronic treatment regimens.
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fMRI of cocaine self-administration in macaques reveals functional inhibition of basal ganglia. Neuropsychopharmacology 2011; 36:1187-98. [PMID: 21307843 PMCID: PMC3079280 DOI: 10.1038/npp.2011.1] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Disparities in cocaine-induced neurochemical and metabolic responses between human beings and rodents motivate the use of non-human primates (NHP) to model consequences of repeated cocaine exposure in human subjects. To characterize the functional response to cocaine infusion in NHP brain, we employed contrast-enhanced fMRI during both non-contingent injection of drug and self-administration of cocaine in the magnet. Cocaine robustly decreased cerebral blood volume (CBV) throughout basal ganglia and motor/pre-motor cortex and produced subtle functional inhibition of prefrontal cortex. No brain regions exhibited significant elevation of CBV in response to cocaine challenge. Theses effects in NHP brain are opposite in sign to the cocaine-induced fMRI response in rats, but consistent with previous measurements in NHP based on glucose metabolism. Because the striatal ratio of D2 to D1 receptors is larger in human beings and NHP than rats, we hypothesize that the inhibitory effects of D2 receptor binding dominate the functional response in primates, whereas excitatory D1 receptor stimulation predominates in the rat. If the NHP accurately models the human response to cocaine, downregulation of D2 receptors in human cocaine-abusing populations can be expected to blunt cocaine-induced functional responses, contributing to the weak and variable fMRI responses reported in human basal ganglia following cocaine infusion.
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Hannestad J, Gallezot JD, Planeta-Wilson B, Lin SF, Williams WA, van Dyck CH, Malison RT, Carson RE, Ding YS. Clinically relevant doses of methylphenidate significantly occupy norepinephrine transporters in humans in vivo. Biol Psychiatry 2010; 68:854-60. [PMID: 20691429 PMCID: PMC3742016 DOI: 10.1016/j.biopsych.2010.06.017] [Citation(s) in RCA: 177] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2010] [Revised: 06/14/2010] [Accepted: 06/17/2010] [Indexed: 10/19/2022]
Abstract
BACKGROUND Attention-deficit/hyperactivity disorder is a psychiatric disorder that starts in childhood. The mechanism of action of methylphenidate, the most common treatment for attention deficit hyperactivity disorder, is unclear. In vitro, the affinity of methylphenidate for the norepinephrine transporter (NET) is higher than that for the dopamine transporter (DAT). The goal of this study was to use positron emission tomography to measure the occupancy of brain norepinephrine transporter by methylphenidate in vivo in humans. METHODS We used (S,S)-[¹¹C] methylreboxetine ([¹¹C]MRB) to determine the effective dose 50 (ED₅₀) of methylphenidate for NET. In a within-subject design, healthy subjects (n = 11) received oral, single-blind placebo and 2.5, 10, and 40 mg of methylphenidate 75 min before [¹¹C]MRB injection. Dynamic positron emission tomography imaging was performed for 2 hours with the High Resolution Research Tomograph. The multilinear reference tissue model with occipital cortex as the reference region was used to estimate binding potential non-displaceable (BP(ND)) in the thalamus and other NET-rich regions. RESULTS BP(ND) was reduced by methylphenidate in a dose-dependent manner in thalamus and other NET-rich regions. The global ED₅₀ was estimated to be .14 mg/kg; therefore, the average clinical maintenance dose of methylphenidate (.35-.55 mg/kg) produces 70% to 80% occupancy of NET. CONCLUSIONS For the first time in humans, we demonstrate that oral methylphenidate significantly occupies NET at clinically relevant doses. The ED₅₀ is lower than that for DAT (.25 mg/kg), suggesting the potential relevance of NET inhibition in the therapeutic effects of methylphenidate in attention-deficit/hyperactivity disorder.
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Affiliation(s)
- Jonas Hannestad
- Department of Psychiatry, Yale PET Center, Yale University School of Medicine, New Haven, Connecticut, USA
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Gallezot JD, Weinzimmer D, Nabulsi N, Lin SF, Fowles K, Sandiego C, McCarthy TJ, Maguire RP, Carson RE, Ding YS. Evaluation of [(11)C]MRB for assessment of occupancy of norepinephrine transporters: Studies with atomoxetine in non-human primates. Neuroimage 2010; 56:268-79. [PMID: 20869448 DOI: 10.1016/j.neuroimage.2010.09.040] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2010] [Accepted: 09/16/2010] [Indexed: 12/15/2022] Open
Abstract
[(11)C]MRB is one of the most promising radioligands used to measure brain norepinephrine transporters (NET) with positron emission tomography (PET). The objective of this study was to evaluate the suitability of [(11)C]MRB for drug occupancy studies of NET using atomoxetine (ATX), a NET uptake inhibitor used in the treatment of depression and attention-deficit hyperactivity disorder (ADHD). A second goal of the study was identification of a suitable reference region. Ten PET studies were performed in three anesthetized rhesus monkeys following an infusion of ATX or placebo. [(11)C]MRB arterial input functions and ATX plasma levels were also measured. A dose-dependent reduction of [(11)C]MRB volume of distribution was observed after correction for [(11)C]MRB plasma free fraction. ATX IC(50) was estimated to be 31 ± 10ng/mL plasma. This corresponds to an effective dose (ED(50)) of 0.13mg/kg, which is much lower than the therapeutic dose of ATX in ADHD (1.0-1.5mg/kg). [(11)C]MRB binding potential BP(ND) in the thalamus was estimated to be 1.8 ± 0.3. Defining a reference region for a NET radiotracer is challenging due to the widespread and relatively uniform distribution of NET in the brain. Three regions were evaluated for use as reference region: caudate, putamen and occipital cortex. Caudate was found to be the most suitable for preclinical drug occupancy studies in rhesus monkeys. The IC(50) estimate obtained using MRTM2 BP(ND) without arterial blood sampling was 21 ± 3ng/mL (using caudate as the reference region). This study demonstrated that [(11)C]MRB is suitable for drug occupancy studies of NET.
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Abstract
BACKGROUND AND PURPOSE There is increasing evidence that not only the monoaminergic but also the glutamatergic system is involved in the pathophysiology of attention-deficit hyperactivity disorder (ADHD). Hyperactivity of glutamate metabolism might be causally related to a hypoactive state in the dopaminergic system. Atomoxetine, a selective noradrenaline reuptake inhibitor, is the first non-stimulant approved for the treatment of this disorder. Here we have evaluated the effects of atomoxetine on glutamate receptors in vitro. EXPERIMENTAL APPROACH The whole-cell configuration of the patch-clamp technique was used to analyse the effect of atomoxetine on N-methyl-d-aspartate (NMDA) receptors in cultured rodent cortical and hippocampal neurons as well as on NMDA receptors heterologously expressed in human TsA cells. KEY RESULTS Atomoxetine blocked NMDA-induced membrane currents. Half-maximal inhibition emerged at about 3 microM which is in the range of clinically relevant concentrations found in plasma of patients treated with this drug. The inhibition was voltage-dependent, indicating an open-channel blocking mechanism. Furthermore, the inhibitory potency of atomoxetine did not vary when measured on NMDA receptors from different brain regions or with different subunit compositions. CONCLUSIONS AND IMPLICATIONS The effective NMDA receptor antagonism by atomoxetine at low micromolar concentrations may be relevant to its clinical effects in the treatment of ADHD. Our data provide further evidence that altered glutamatergic transmission might play a role in ADHD pathophysiology.
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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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Hazell P, Becker K, Nikkanen EA, Trzepacz PT, Tanaka Y, Tabas L, D'Souza DN, Witcher J, Long A, Ponsler G, Dittmann RW. Relationship between atomoxetine plasma concentration, treatment response and tolerability in attention-deficit/hyperactivity disorder and comorbid oppositional defiant disorder. ACTA ACUST UNITED AC 2009; 1:201-10. [PMID: 20234828 PMCID: PMC2837233 DOI: 10.1007/s12402-009-0012-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2009] [Accepted: 08/30/2009] [Indexed: 11/29/2022]
Abstract
The purpose of this study was to examine whether atomoxetine plasma concentration predicts attention-deficit/hyperactivity disorder (ADHD) or oppositional defiant disorder (ODD) response. This post-hoc analysis assessed the relationship between atomoxetine plasma concentration and ADHD and ODD symptoms in patients (with ADHD and comorbid ODD) aged 6–12 years. Patients were randomly assigned to atomoxetine 1.2 mg/kg/day (n = 156) or placebo (n = 70) for 8 weeks (Study Period II). At the end of 8 weeks, ODD non-remitters (score >9 on the SNAP-IV ODD subscale and CGI-I > 2) with atomoxetine plasma concentration <800 ng/ml at 2 weeks were re-randomized to either atomoxetine 1.2 mg/kg/day or 2.4 mg/kg/day for an additional 4 weeks (Study Period III). ODD remitters and non-remitters with plasma atomoxetine ≥800 ng/ml remained on 1.2 mg/kg/day atomoxetine for 4 weeks. Patients who received atomoxetine, completed Study Period II, and entered Study Period III were included in these analyses. All the groups demonstrated improvement on the SNAP-IV ODD and ADHD-combined subscales (P < .001). At the end of Study Periods II and III, ODD and ADHD improvement was significantly greater in the remitter group compared with the non-remitter groups. Symptom improvement was numerically greater in the non-remitter (2.4 mg/kg/day compared with the non-remitter 1.2 mg/kg/day) group. Atomoxetine plasma concentration was not indicative of ODD and ADHD improvement after 12 weeks of treatment. ADHD and ODD symptoms improved in all the groups with longer duration on atomoxetine. Results suggest atomoxetine plasma concentration does not predict ODD and ADHD symptom improvement. However, a higher atomoxetine dose may benefit some patients.
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Affiliation(s)
- Philip Hazell
- Discipline of Psychological Medicine, Concord Clinical School, University of Sydney, Sydney, Australia
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Takano A, Gulyás B, Varrone A, Halldin C. Comparative evaluations of norepinephrine transporter radioligands with reference tissue models in rhesus monkeys: (S,S)-[18F]FMeNER-D2 and (S,S)-[11C]MeNER. Eur J Nucl Med Mol Imaging 2009; 36:1885-91. [DOI: 10.1007/s00259-009-1194-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2009] [Accepted: 05/28/2009] [Indexed: 10/20/2022]
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Grimwood S, Hartig PR. Target site occupancy: Emerging generalizations from clinical and preclinical studies. Pharmacol Ther 2009; 122:281-301. [DOI: 10.1016/j.pharmthera.2009.03.002] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2009] [Accepted: 03/04/2009] [Indexed: 01/17/2023]
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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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Ray R, Rukstalis M, Jepson C, Strasser A, Patterson F, Lynch K, Lerman C. Effects of atomoxetine on subjective and neurocognitive symptoms of nicotine abstinence. J Psychopharmacol 2009; 23:168-76. [PMID: 18515446 DOI: 10.1177/0269881108089580] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Nicotine dependence has been linked to attention-deficit hyperactivity disorder (ADHD) symptoms in both clinical and general populations. This behavioural pharmacology study used a within-subject, double-blind, crossover design to test the effects of atomoxetine, a medication for ADHD, on nicotine abstinence symptoms. Fifty non treatment-seeking smokers (>/=15 cigarettes/day) completed a baseline session when they were smoking as usual and then two laboratory testing sessions after overnight abstinence and treatment with 7 days of either atomoxetine (1.2 mg/kg) or placebo. During each laboratory session, participants completed subjective measures of abstinence symptoms and performed neurocognitive tasks. In mixed effects models, atomoxetine, compared with placebo, was found to be associated with a reduction in abstinence-induced subjective withdrawal symptoms. Atomoxetine was also associated with significant reductions in self-reported smoking urges amongst smokers who scored high on a baseline measure of smoking for stimulation. However, atomoxetine had no effect on any of the cognitive tasks employed in the study. Thus, atomoxetine may reduce cravings to smoke among smokers who use nicotine to increase arousal.
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Affiliation(s)
- R Ray
- Department of Pharmacology, University of Pennsylvania, Philadelphia, PA, USA
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Zeng F, Mun J, Jarkas N, Stehouwer JS, Voll RJ, Tamagnan GD, Howell L, Votaw JR, Kilts CD, Nemeroff CB, Goodman MM. Synthesis, radiosynthesis, and biological evaluation of carbon-11 and fluorine-18 labeled reboxetine analogues: potential positron emission tomography radioligands for in vivo imaging of the norepinephrine transporter. J Med Chem 2009; 52:62-73. [PMID: 19067522 DOI: 10.1021/jm800817h] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Reboxetine analogues with methyl and fluoroalkyl substituents at position 2 of the phenoxy ring 1-4 were synthesized. In vitro competition binding with [(3)H]nisoxetine demonstrated that 1-4 have a high affinity for the norepinephrine transporter (NET) with K(i)'s = 1.02, 3.14, 3.68, and 0.30 nM, respectively. MicroPET imaging in rhesus monkeys showed that the relative regional distribution of [(11)C]1 and [(11)C]4 is consistent with distribution of the NET in the brain, while [(18)F]2 and [(18)F]3 showed only slight regional differentiation in brain uptake. Especially, the highest ratios of uptake of [(11)C]1 in NET-rich regions to that in caudate were obtained at 1.30-1.45 at 45 min and remained relatively constant over 85 min. Pretreatment of the monkey with the selective NET inhibitor, desipramine, decreased the specific binding for both [(11)C]1 and [(11)C]4. PET imaging in awake monkeys suggested that anesthesia influenced the binding potential of [(11)C]1 and [(11)C]4 at the NET.
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Affiliation(s)
- Fanxing Zeng
- Department of Radiology, Yerkes Regional Primate Research Center, Emory University, Atlanta, Georgia 30322, USA
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Zolkowska D, Jain R, Rothman RB, Partilla JS, Roth BL, Setola V, Prisinzano TE, Baumann MH. Evidence for the involvement of dopamine transporters in behavioral stimulant effects of modafinil. J Pharmacol Exp Ther 2009; 329:738-46. [PMID: 19197004 DOI: 10.1124/jpet.108.146142] [Citation(s) in RCA: 153] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Modafinil is prescribed for numerous medical conditions, but the drug's mechanism of action is unclear. Here, we examined the interaction of modafinil with receptors and transporters in vitro and compared pharmacological effects of the drug with those produced by indirect dopamine (DA) agonists 1-[2-[bis(4-fluorophenyl)methoxy]ethyl]-4-(3-phenylpropyl)piperazine (GBR12909) and (+)-methamphetamine (METH). Modafinil was screened at various receptors and transporters using binding assays. Transporter-mediated uptake and release were examined in rat brain synaptosomes. Effects of modafinil on motor activity and neurochemistry were determined in rats undergoing in vivo microdialysis in nucleus accumbens. Of the receptors and transporters assayed, modafinil displayed measurable potency only at DA transporters (DAT), inhibiting [(3)H]DA uptake, with an IC(50) value of 4.0 microM. Accordingly, modafinil pretreatment (10 microM) antagonized METH-induced release of the DAT substrate [(3)H]1-methyl-4-phenylpyridinium. Intravenous modafinil (20 and 60 mg/kg) produced dose-dependent increases in motor activity and extracellular DA, without affecting serotonin (5-HT). Analogous results were observed for GBR12909 (1 and 3 mg/kg), whereas METH (0.3 and 1 mg/kg) increased DA and 5-HT. Locomotor effects of all drugs were positively correlated with dialysate DA (P < 0.001). Interestingly, modafinil pretreatment reduced METH-induced ambulation and DA release. Our data show that modafinil interacts with DAT sites in rat brain, a property shared with agonist medications under investigation for treating cocaine dependence. Nondopaminergic mechanisms may also contribute to the pharmacology of modafinil. Finally, the results suggest that modafinil should be tested as an adjunct for treating METH addiction.
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Affiliation(s)
- Dorota Zolkowska
- Clinical Psychopharmacology Section, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA
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Abstract
Neuroimaging, particularly that of neuroreceptor radioisotope and functional magnetic resonance imaging (fMRI), has played a fundamental role in neuropharmacology and neurophysiology. Because of the unique and pioneering role, especially of the radiolabeling of central nervous system (CNS) drugs for receptor and neurotransmitter system imaging, there is an increasingly major role to aid in CNS drug development. One component is providing evidence for proof of concept of the target for which candidate drugs are being tested for receptor occupancy mechanism of action and ultimately rational drug dosing. There is also a role for other areas of neuroimaging, including fMRI and magnetic resonance spectroscopy in other magnetic resonance-based techniques that, together with radioisotope imaging, represent 'CNS molecular imaging.' The role of these approaches and a review of the recent advances in such neuroimaging for proof-of-concept studies is the subject for this paper. Moreover, hypothetical examples and possible algorithms for early discovery/phase I development using neuroimaging provide specific working approaches. In summary, this article reviews the vital biomarker approach of neuroimaging in proof of concept studies.
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Takano A, Varrone A, Gulyás B, Karlsson P, Tauscher J, Halldin C. Mapping of the norepinephrine transporter in the human brain using PET with (S,S)-[18F]FMeNER-D2. Neuroimage 2008; 42:474-82. [DOI: 10.1016/j.neuroimage.2008.05.040] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2008] [Revised: 05/12/2008] [Accepted: 05/15/2008] [Indexed: 12/15/2022] Open
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Arakawa R, Okumura M, Ito H, Seki C, Takahashi H, Takano H, Nakao R, Suzuki K, Okubo Y, Halldin C, Suhara T. Quantitative analysis of norepinephrine transporter in the human brain using PET with (S,S)-18F-FMeNER-D2. J Nucl Med 2008; 49:1270-6. [PMID: 18632811 DOI: 10.2967/jnumed.108.051292] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
UNLABELLED (S,S)-18F-FMeNER-D2 was recently developed as a radioligand for the measurement of norepinephrine transporter imaging with PET. In this study, a norepinephrine transporter was visualized in the human brain using this radioligand with PET and quantified by several methods. METHODS PET scans were performed on 10 healthy men after intravenous injection of (S,S)-18F-FMeNER-D2. Binding potential relative to nondisplaceable binding (BP(ND)) was quantified by the indirect kinetic, simplified reference-tissue model (SRTM), multilinear reference-tissue model (MRTM), and ratio methods. The indirect kinetic method was used as the gold standard and was compared with the SRTM method with scan times of 240 and 180 min, the MRTM method with a scan time of 240 min, and the ratio method with a time integration interval of 120-180 min. The caudate was used as reference brain region. RESULTS Regional radioactivity was highest in the thalamus and lowest in the caudate during PET scanning. BP(ND) values by the indirect kinetic method were 0.54 +/- 0.19 and 0.35 +/- 0.25 in the thalamus and locus coeruleus, respectively. BP(ND) values found by the SRTM, MRTM, and ratio methods agreed with the values demonstrated by the indirect kinetic method (r = 0.81-0.92). CONCLUSION The regional distribution of (S,S)-18F-FMeNER-D2 in our study agreed with that demonstrated by previous PET and postmortem studies of norepinephrine transporter in the human brain. The ratio method with a time integration interval of 120-180 min will be useful for clinical research of psychiatric disorders for estimation of norepinephrine transporter occupancy by antidepressants without requiring arterial blood sampling and dynamic PET.
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Affiliation(s)
- Ryosuke Arakawa
- Molecular Neuroimaging Group, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba, Japan
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Lerner A, Bagic A. Olfactory pathogenesis of idiopathic Parkinson disease revisited. Mov Disord 2008; 23:1076-84. [DOI: 10.1002/mds.22066] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
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Dalley JW, Fryer TD, Aigbirhio FI, Brichard L, Richards HK, Hong YT, Baron JC, Everitt BJ, Robbins TW. Modelling human drug abuse and addiction with dedicated small animal positron emission tomography. Neuropharmacology 2008; 56 Suppl 1:9-17. [PMID: 18614184 DOI: 10.1016/j.neuropharm.2008.05.029] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2008] [Revised: 05/16/2008] [Accepted: 05/24/2008] [Indexed: 11/19/2022]
Abstract
Drug addiction is a chronically relapsing brain disorder, which causes substantial harm to the addicted individual and society as a whole. Despite considerable research we still do not understand why some people appear particularly disposed to drug abuse and addiction, nor do we understand how frequently co-morbid brain disorders such as depression and attention-deficit hyperactivity disorder (ADHD) contribute causally to the emergence of addiction-like behaviour. In recent years positron emission tomography (PET) has come of age as a translational neuroimaging technique in the study of drug addiction, ADHD and other psychopathological states in humans. PET provides unparalleled quantitative assessment of the spatial distribution of radiolabelled molecules in the brain and because it is non-invasive permits longitudinal assessment of physiological parameters such as binding potential in the same subject over extended periods of time. However, whilst there are a burgeoning number of human PET experiments in ADHD and drug addiction there is presently a paucity of PET imaging studies in animals despite enormous advances in our understanding of the neurobiology of these disorders based on sophisticated animal models. This article highlights recent examples of successful cross-species convergence of findings from PET studies in the context of drug addiction and ADHD and identifies how small animal PET can more effectively be used to model complex psychiatric disorders involving at their core impaired behavioural self-control.
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Affiliation(s)
- Jeffrey W Dalley
- Behavioural and Clinical Neuroscience Institute, University of Cambridge, Downing Street, Cambridge, CB2 3EB, UK.
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