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Armand S, Ozenne B, Svart N, Frøkjaer VG, Knudsen GM, Fisher PM, Stenbaek DS. Brain serotonin transporter is associated with cognitive-affective biases in healthy individuals. Hum Brain Mapp 2022; 43:4174-4184. [PMID: 35607850 PMCID: PMC9374883 DOI: 10.1002/hbm.25946] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Revised: 04/21/2022] [Accepted: 05/02/2022] [Indexed: 12/26/2022] Open
Abstract
Cognitive affective biases describe the tendency to process negative information or positive information over the other. These biases can be modulated by changing extracellular serotonin (5-HT) levels in the brain, for example, by pharmacologically blocking and downregulating the 5-HT transporter (5-HTT), which remediates negative affective bias. This suggests that higher levels of 5-HTT are linked to a priority of negative information over positive, but this link remains to be tested in vivo in healthy individuals. We, therefore, evaluated the association between 5-HTT levels, as measured with [11 C]DASB positron emission tomography (PET), and affective biases, hypothesising that higher 5-HTT levels are associated with a more negative bias. We included 98 healthy individuals with measures of [11 C]DASB binding potential (BPND ) and affective biases using The Emotional Faces Identification Task by subtracting the per cent hit rate for happy from that of sad faces (EFITAB ). We evaluated the association between [11 C]DASB BPND and EFITAB in a linear latent variable model, with the latent variable (5-HTTLV ) modelled from [11 C]DASB BPND in the fronto-striatal and fronto-limbic networks implicated in affective cognition. We observed an inverse association between 5-HTTLV and EFITAB (β = -8% EFITAB per unit 5-HTTLV , CI = -14% to -3%, p = .002). These findings show that higher 5-HTT levels are linked to a more negative bias in healthy individuals. High 5-HTT supposedly leads to high clearance of 5-HT, and thus, a negative bias could result from low extracellular 5-HT. Future studies must reveal if a similar inverse association exists in individuals with affective disorders.
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Affiliation(s)
- Sophia Armand
- Neurobiology Research Unit, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark.,Department of Psychology, University of Copenhagen, Copenhagen, Denmark
| | - Brice Ozenne
- Neurobiology Research Unit, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark.,Department of Public Health, Section of Biostatistics, University of Copenhagen, Copenhagen, Denmark.,BrainDrugs, Neurobiology Research Unit, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Nanna Svart
- Neurobiology Research Unit, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark.,Department of Psychology, University of Copenhagen, Copenhagen, Denmark
| | - Vibe G Frøkjaer
- Neurobiology Research Unit, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark.,BrainDrugs, Neurobiology Research Unit, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark.,Psychiatric Center Copenhagen, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Gitte M Knudsen
- Neurobiology Research Unit, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark.,BrainDrugs, Neurobiology Research Unit, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark.,Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Patrick M Fisher
- Neurobiology Research Unit, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark.,BrainDrugs, Neurobiology Research Unit, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Dea S Stenbaek
- Neurobiology Research Unit, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark.,Department of Psychology, University of Copenhagen, Copenhagen, Denmark.,BrainDrugs, Neurobiology Research Unit, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
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Mangeant R, Dubost E, Cailly T, Collot V. Radiotracers for the Central Serotoninergic System. Pharmaceuticals (Basel) 2022; 15:571. [PMID: 35631397 PMCID: PMC9143978 DOI: 10.3390/ph15050571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 04/27/2022] [Accepted: 04/28/2022] [Indexed: 12/10/2022] Open
Abstract
This review lists the most important radiotracers described so far for imaging the central serotoninergic system. Single-photon emission computed tomography and positron emission tomography radiotracers are reviewed and critically discussed for each receptor.
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Affiliation(s)
- Reynald Mangeant
- Centre d’Etudes et de Recherche sur le Médicament de Normandie (CERMN), UNICAEN, Normandie Univ., 14000 Caen, France; (R.M.); (E.D.)
- Institut Blood and Brain @ Caen Normandie (BB@C), Boulevard Henri Becquerel, 14000 Caen, France
| | - Emmanuelle Dubost
- Centre d’Etudes et de Recherche sur le Médicament de Normandie (CERMN), UNICAEN, Normandie Univ., 14000 Caen, France; (R.M.); (E.D.)
- Institut Blood and Brain @ Caen Normandie (BB@C), Boulevard Henri Becquerel, 14000 Caen, France
| | - Thomas Cailly
- Centre d’Etudes et de Recherche sur le Médicament de Normandie (CERMN), UNICAEN, Normandie Univ., 14000 Caen, France; (R.M.); (E.D.)
- Institut Blood and Brain @ Caen Normandie (BB@C), Boulevard Henri Becquerel, 14000 Caen, France
- UNICAEN, IMOGERE, Normandie Univ., 14000 Caen, France
- CHU Côte de Nacre, Department of Nuclear Medicine, 14000 Caen, France
| | - Valérie Collot
- Centre d’Etudes et de Recherche sur le Médicament de Normandie (CERMN), UNICAEN, Normandie Univ., 14000 Caen, France; (R.M.); (E.D.)
- Institut Blood and Brain @ Caen Normandie (BB@C), Boulevard Henri Becquerel, 14000 Caen, France
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Xu Y, Kappen M, Peremans K, De Bundel D, Van Eeckhaut A, Van Laeken N, De Vos F, Dobbeleir A, Saunders JH, Baeken C. Accelerated HF-rTMS Modifies SERT Availability in the Subgenual Anterior Cingulate Cortex: A Canine [ 11C]DASB Study on the Serotonergic System. J Clin Med 2022; 11:jcm11061531. [PMID: 35329857 PMCID: PMC8950510 DOI: 10.3390/jcm11061531] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 02/04/2022] [Accepted: 03/08/2022] [Indexed: 02/04/2023] Open
Abstract
Repetitive transcranial magnetic stimulation (rTMS) is thought to partly exert its antidepressant action through the serotonergic system. Accelerated rTMS may have the potential to result in similar but faster onset of clinical improvement compared to the classical daily rTMS protocols, but given that delayed clinical responses have been reported, the neurobiological effects of accelerated paradigms remain to be elucidated including on this neurotransmitter system. This sham-controlled study aimed to evaluate the effects of accelerated high frequency rTMS (aHF-rTMS) over the left frontal cortex on the serotonin transporter (SERT) in healthy beagle dogs. A total of twenty-two dogs were randomly divided into three unequal groups: five active stimulation sessions (five sessions in one day, n = 10), 20 active stimulation sessions (five sessions/day for four days, n = 8), and 20 sham stimulation sessions (five sessions/day for four days, n = 4). The SERT binding index (BI) was obtained at baseline, 24 h post stimulation protocol, one month, and three months post stimulation by a [11C]DASB PET scan. It was found that one day of active aHF-rTMS (five sessions) did not result in significant SERT BI changes at any time point. For the 20 sessions of active aHF-rTMS, one month after stimulation the SERT BI attenuated in the sgACC. No significant SERT BI changes were found after 20 sessions of sham aHF-rTMS. A total of four days of active aHF-rTMS modified sgACC SERT BI one month post-stimulation, explaining to some extent the delayed clinical effects of accelerated rTMS paradigms found in human psychopathologies.
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Affiliation(s)
- Yangfeng Xu
- Department of Psychiatry and Medical Psychology, Ghent Experimental Psychiatry (GHEP) Lab, Ghent University, 9000 Ghent, Belgium; (M.K.); (C.B.)
- Department of Veterinary Medical Imaging and Small Animal Othopaedics, Faculty of Veterinary Medicine, Ghent University, 9820 Merelbeke, Belgium; (K.P.); (A.D.); (J.H.S.)
- Correspondence:
| | - Mitchel Kappen
- Department of Psychiatry and Medical Psychology, Ghent Experimental Psychiatry (GHEP) Lab, Ghent University, 9000 Ghent, Belgium; (M.K.); (C.B.)
| | - Kathelijne Peremans
- Department of Veterinary Medical Imaging and Small Animal Othopaedics, Faculty of Veterinary Medicine, Ghent University, 9820 Merelbeke, Belgium; (K.P.); (A.D.); (J.H.S.)
| | - Dimitri De Bundel
- Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information (FASC), Research Group Experimental Pharmacology (EFAR), Center for Neurosciences (C4N), Vrije Universiteit Brussel, 1000 Brussels, Belgium; (D.D.B.); (A.V.E.)
| | - Ann Van Eeckhaut
- Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information (FASC), Research Group Experimental Pharmacology (EFAR), Center for Neurosciences (C4N), Vrije Universiteit Brussel, 1000 Brussels, Belgium; (D.D.B.); (A.V.E.)
| | - Nick Van Laeken
- Laboratory of Radiopharmacy, Department of Pharmaceutical Analysis, Faculty of Pharmaceutical Sciences, Ghent University, 9000 Ghent, Belgium; (N.V.L.); (F.D.V.)
| | - Filip De Vos
- Laboratory of Radiopharmacy, Department of Pharmaceutical Analysis, Faculty of Pharmaceutical Sciences, Ghent University, 9000 Ghent, Belgium; (N.V.L.); (F.D.V.)
| | - Andre Dobbeleir
- Department of Veterinary Medical Imaging and Small Animal Othopaedics, Faculty of Veterinary Medicine, Ghent University, 9820 Merelbeke, Belgium; (K.P.); (A.D.); (J.H.S.)
| | - Jimmy H. Saunders
- Department of Veterinary Medical Imaging and Small Animal Othopaedics, Faculty of Veterinary Medicine, Ghent University, 9820 Merelbeke, Belgium; (K.P.); (A.D.); (J.H.S.)
| | - Chris Baeken
- Department of Psychiatry and Medical Psychology, Ghent Experimental Psychiatry (GHEP) Lab, Ghent University, 9000 Ghent, Belgium; (M.K.); (C.B.)
- Department of Psychiatry, Vrije Universiteit Brussel (VUB), Universitair Ziekenhuis Brussel (UZBrussel), 1000 Brussels, Belgium
- Department of Electrical Engineering, Eindhoven University of Technology, 5612 Eindhoven, The Netherlands
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Goud NS, Bhattacharya A, Joshi RK, Nagaraj C, Bharath RD, Kumar P. Carbon-11: Radiochemistry and Target-Based PET Molecular Imaging Applications in Oncology, Cardiology, and Neurology. J Med Chem 2021; 64:1223-1259. [PMID: 33499603 DOI: 10.1021/acs.jmedchem.0c01053] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The positron emission tomography (PET) molecular imaging technique has gained its universal value as a remarkable tool for medical diagnosis and biomedical research. Carbon-11 is one of the promising radiotracers that can report target-specific information related to its pharmacology and physiology to understand the disease status. Currently, many of the available carbon-11 (t1/2 = 20.4 min) PET radiotracers are heterocyclic derivatives that have been synthesized using carbon-11 inserted different functional groups obtained from primary and secondary carbon-11 precursors. A spectrum of carbon-11 PET radiotracers has been developed against many of the upregulated and emerging targets for the diagnosis, prognosis, prediction, and therapy in the fields of oncology, cardiology, and neurology. This review focuses on the carbon-11 radiochemistry and various target-specific PET molecular imaging agents used in tumor, heart, brain, and neuroinflammatory disease imaging along with its associated pathology.
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Affiliation(s)
- Nerella Sridhar Goud
- Department of Neuroimaging and Interventional Radiology (NIIR), National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru 560 029, India
| | - Ahana Bhattacharya
- Department of Neuroimaging and Interventional Radiology (NIIR), National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru 560 029, India
| | - Raman Kumar Joshi
- Department of Neuroimaging and Interventional Radiology (NIIR), National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru 560 029, India
| | - Chandana Nagaraj
- Department of Neuroimaging and Interventional Radiology (NIIR), National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru 560 029, India
| | - Rose Dawn Bharath
- Department of Neuroimaging and Interventional Radiology (NIIR), National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru 560 029, India
| | - Pardeep Kumar
- Department of Neuroimaging and Interventional Radiology (NIIR), National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru 560 029, India
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Kim JH, Son YD, Kim HK, Kim JH. Association Between Lack of Insight and Prefrontal Serotonin Transporter Availability in Antipsychotic-Free Patients with Schizophrenia: A High-Resolution PET Study with [ 11C]DASB. Neuropsychiatr Dis Treat 2021; 17:3195-3203. [PMID: 34707358 PMCID: PMC8544267 DOI: 10.2147/ndt.s336126] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 10/08/2021] [Indexed: 02/03/2023] Open
Abstract
BACKGROUND Previous studies suggested a link between serotonergic neurotransmission and impaired insight in schizophrenia. In this study, we examined the relationship between serotonin transporter (SERT) availability in regions of the prefrontal cortex (dorsolateral, ventrolateral, ventromedial, and orbitofrontal cortices) and insight deficits in antipsychotic-free patients with schizophrenia using high-resolution positron emission tomography (PET) with [11C]DASB. METHODS Nineteen patients underwent [11C]DASB PET and 7-Tesla magnetic resonance imaging scans. To assess SERT availability, the binding potential with respect to non-displaceable compartment (BPND) was derived using the simplified reference tissue model. Patients' level of insight was assessed using the Insight and Treatment Attitude Questionnaire (ITAQ). The relationship between ITAQ scores and [11C]DASB BPND values was examined using the region-of-interest (ROI)- and voxel-based analyses with relevant variables as covariates. The prefrontal cortex and its four subregions were selected as a priori ROIs since the prefrontal cortex has been implicated as the critical neuroanatomical substrate of impaired insight in schizophrenia. RESULTS The ROI-based analysis revealed that the ITAQ illness insight dimension had significant negative correlations with the [11C]DASB BPND in the left dorsolateral, left orbitofrontal, and bilateral ventrolateral prefrontal cortices. The ITAQ treatment insight dimension had significant negative correlations with the [11C]DASB BPND in the bilateral dorsolateral, left orbitofrontal, and bilateral ventrolateral prefrontal cortices. The ITAQ total score showed significant negative correlations with the [11C]DASB BPND in the bilateral prefrontal cortex and three subregions (dorsolateral, ventrolateral, and orbitofrontal cortices). A supplementary voxel-based analysis corroborated a significant negative association between the ITAQ score and the [11C]DASB BPND in the prefrontal cortices. CONCLUSION Our study provides in vivo evidence of significant negative correlations between insight deficits and prefrontal SERT availability in patients with schizophrenia, suggesting significant involvement of prefrontal serotonergic signaling in impaired insight, one of the core symptoms of schizophrenia.
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Affiliation(s)
- Jeong-Hee Kim
- Neuroscience Research Institute, Gachon University, Incheon, Republic of Korea.,Department of Biomedical Engineering, College of Health Science, Gachon University, Incheon, Republic of Korea
| | - Young-Don Son
- Neuroscience Research Institute, Gachon University, Incheon, Republic of Korea.,Department of Biomedical Engineering, College of Health Science, Gachon University, Incheon, Republic of Korea.,Gachon Advanced Institute for Health Sciences & Technology, Gachon University, Incheon, Republic of Korea
| | - Hang-Keun Kim
- Neuroscience Research Institute, Gachon University, Incheon, Republic of Korea.,Department of Biomedical Engineering, College of Health Science, Gachon University, Incheon, Republic of Korea.,Gachon Advanced Institute for Health Sciences & Technology, Gachon University, Incheon, Republic of Korea
| | - Jong-Hoon Kim
- Neuroscience Research Institute, Gachon University, Incheon, Republic of Korea.,Gachon Advanced Institute for Health Sciences & Technology, Gachon University, Incheon, Republic of Korea.,Department of Psychiatry, Gachon University College of Medicine, Gil Medical Center, Incheon, Republic of Korea
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Huang WS, Chen GJ, Tsai TH, Cheng CY, Shiue CY, Ma KH, Yeh SHH. In vivo long-lasting alterations of central serotonin transporter activity and associated dopamine synthesis after acute repeated administration of methamphetamine. EJNMMI Res 2019; 9:92. [PMID: 31535286 PMCID: PMC6751231 DOI: 10.1186/s13550-019-0557-y] [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: 04/25/2019] [Accepted: 08/23/2019] [Indexed: 11/22/2022] Open
Abstract
Background Methamphetamine (METH)-associated alterations in the striatal dopamine (DA) system or dopamine transport (DAT) have been identified in clinical and preclinical studies with positron emission tomography (PET) imaging but have not been well correlated with in vivo serotonin transporter (SERT) availability due to the lack of appropriate imaging agents to assess SERTs. N,N-dimethyl-2-(2-amino-4-[18F]-fluorophenylthio) benzylamine (4-[18F]-ADAM) has been developed by our group and validated for its high affinity and selectivity for SERTs, allowing the in vivo examination of SERT density, location, and binding function. The aims of this study were to investigate the potential of SERT imaging using 4-[18F]-ADAM PET to estimate the long-lasting effects of METH-induced serotonergic neurotoxicity, and further determine whether a correlative relationship exists between SERT availability/activity and tyrosine hydroxylase (TH) activity in various brain regions due to the long-lasting consequences of METH treatment. Results Male rats received four administrations of METH (5 or 10 mg/kg, s.c.) or saline (1 ml/kg, s.c.) at 1-h intervals. At 30 days post-administration, in vivo SERT availability and activity were measured by 4-[18F]ADAM PET imaging. In contrast to the controls, the uptake of 4-[18F]ADAM in METH-treated mice was significantly reduced in a dose-dependent manner in the midbrain, followed by the hypothalamus, thalamus, striatum, hippocampus, and frontal cortex. The regional effects of METH on TH activity were assessed by quantitative immunohistochemistry and presented as integrated optical density (IOD). A significant decrease in TH immunostaining and IOD ratios was seen in the caudate, putamen, nucleus accumbens, substantia nigra pars compacta, and substantia nigra pars reticulata in the METH-treated rats compared to controls. Conclusion The present results suggested that the long-lasting response to METH decreased the uptake of 4-[18F]-ADAM and varied regionally along with TH immunoreactivity. In addition, 4-[18F]ADAM PET could be used to detect serotonergic neuron loss and to evaluate the severity of serotonergic neurotoxicity of METH.
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Affiliation(s)
- Wen-Sheng Huang
- Department of Nuclear Medicine, Taipei Veterans General Hospital, No. 201, Sec. 2, Shipai Rd., Beitou District, Taipei City, 11217, Taiwan, Republic of China.,Nuclear Medicine Department, Tri-Service General Hospital, Taipei, Taiwan
| | - Guann-Juh Chen
- Department of Neurological Surgery, National Defense Medical Center, Tri-Service General Hospital, No. 325, Sec. 2, Chenggong Rd., Neihu District, Taipei City, 11490, Taiwan, Republic of China.,Department of Neurological Surgery, Chiayi Branch, Taichung Veterans General Hospital, No. 600, Sec. 2, Shixian Rd., West District, Chiayi City, 60090, Taiwan, Republic of China
| | - Tung-Han Tsai
- Department of Neurological Surgery, National Defense Medical Center, Tri-Service General Hospital, No. 325, Sec. 2, Chenggong Rd., Neihu District, Taipei City, 11490, Taiwan, Republic of China
| | - Chen-Yi Cheng
- Nuclear Medicine Department, Tri-Service General Hospital, Taipei, Taiwan
| | - Chyng-Yann Shiue
- Department of Nuclear Medicine, National Taiwan University Hospital, No. 1, Changde St., Zhongzheng District, Taipei City, 10048, Taiwan, Republic of China
| | - Kuo-Hsing Ma
- Department of Anatomy and Biology, National Defense Medical Center, No. 161, Sec. 6, Minquan E. Rd., Neihu District, Taipei City, 11490, Taiwan, Republic of China.
| | - Skye Hsin-Hsien Yeh
- Brain Research Center, National Yang-Ming University, No. 155, Sec. 2, Linong Street, Taipei City, 112, Taiwan, Republic of China.
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Taylor O, Audenaert K, Baeken C, Saunders J, Peremans K. Nuclear medicine for the investigation of canine behavioral disorders. J Vet Behav 2016. [DOI: 10.1016/j.jveb.2016.08.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Van Laeken N, Taylor O, Polis I, Neyt S, Kersemans K, Dobbeleir A, Saunders J, Goethals I, Peremans K, De Vos F. In Vivo Evaluation of Blood Based and Reference Tissue Based PET Quantifications of [11C]DASB in the Canine Brain. PLoS One 2016; 11:e0148943. [PMID: 26859850 PMCID: PMC4747581 DOI: 10.1371/journal.pone.0148943] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Accepted: 01/23/2016] [Indexed: 11/19/2022] Open
Abstract
This first-in-dog study evaluates the use of the PET-radioligand [11C]DASB to image the density and availability of the serotonin transporter (SERT) in the canine brain. Imaging the serotonergic system could improve diagnosis and therapy of multiple canine behavioural disorders. Furthermore, as many similarities are reported between several human neuropsychiatric conditions and naturally occurring canine behavioural disorders, making this tracer available for use in dogs also provide researchers an interesting non-primate animal model to investigate human disorders. Five adult beagles underwent a 90 minutes dynamic PET scan and arterial whole blood was sampled throughout the scan. For each ROI, the distribution volume (VT), obtained via the one- and two- tissue compartment model (1-TC, 2-TC) and the Logan Plot, was calculated and the goodness-of-fit was evaluated by the Akaike Information Criterion (AIC). For the preferred compartmental model BPND values were estimated and compared with those derived by four reference tissue models: 4-parameter RTM, SRTM2, MRTM2 and the Logan reference tissue model. The 2-TC model indicated in 61% of the ROIs a better fit compared to the 1-TC model. The Logan plot produced almost identical VT values and can be used as an alternative. Compared with the 2-TC model, all investigated reference tissue models showed high correlations but small underestimations of the BPND-parameter. The highest correlation was achieved with the Logan reference tissue model (Y = 0.9266 x + 0.0257; R2 = 0.9722). Therefore, this model can be put forward as a non-invasive standard model for future PET-experiments with [11C]DASB in dogs.
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Affiliation(s)
- Nick Van Laeken
- Department of Radiopharmacy, Ghent University, Ghent, Belgium
- * E-mail:
| | - Olivia Taylor
- Department of Medical Imaging and Small Animal Orthopedics, Ghent University, Ghent, Belgium
| | - Ingeborgh Polis
- Department of Medicine and Clinical Biology of Small Animals, Ghent University, Ghent, Belgium
| | - Sara Neyt
- Department of Radiopharmacy, Ghent University, Ghent, Belgium
| | - Ken Kersemans
- Department of Radiology and Nuclear Medicine, Ghent University Hospital, Ghent, Belgium
| | - Andre Dobbeleir
- Department of Radiology and Nuclear Medicine, Ghent University Hospital, Ghent, Belgium
| | - Jimmy Saunders
- Department of Medical Imaging and Small Animal Orthopedics, Ghent University, Ghent, Belgium
| | - Ingeborg Goethals
- Department of Radiology and Nuclear Medicine, Ghent University Hospital, Ghent, Belgium
| | - Kathelijne Peremans
- Department of Medical Imaging and Small Animal Orthopedics, Ghent University, Ghent, Belgium
| | - Filip De Vos
- Department of Radiopharmacy, Ghent University, Ghent, Belgium
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Taylor O, Van Laeken N, De Vos F, Polis I, Bosmans T, Goethals I, Achten R, Dobbeleir A, Vandermeulen E, Baeken C, Saunders J, Peremans K. In vivo quantification of the [(11)C]DASB binding in the normal canine brain using positron emission tomography. BMC Vet Res 2015; 11:308. [PMID: 26704517 PMCID: PMC4690221 DOI: 10.1186/s12917-015-0622-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 12/18/2015] [Indexed: 11/17/2022] Open
Abstract
Background [11C]-3-amino-4-(2-dimethylaminomethyl-phenylsulfanyl)-benzonitrile ([11C]DASB) is currently the mostly used radiotracer for positron emission tomography (PET) quantitative studies of the serotonin transporter (SERT) in the human brain but has never been validated in dogs. The first objective was therefore to evaluate normal [11C]DASB distribution in different brain regions of healthy dogs using PET. The second objective was to provide less invasive and more convenient alternative methods to the arterial sampling-based kinetic analysis. Results A dynamic acquisition of the brain was performed during 90 min. The PET images were coregistered with the magnetic resonance images taken prior to the study in order to manually drawn 20 regions of interest (ROIs). The highest radioactivity concentration of [11C]DASB was observed in the hypothalamus, raphe nuclei and thalamus and lowest levels in the parietal cortex, occipital cortex and cerebellum. The regional radioactivity in those 20 ROIs was quantified using the multilinear reference tissue model 2 (MRTM2) and a semi-quantitative method. The values showed least variability between 40 and 60 min and this time interval was set as the optimal time interval for [11C]DASB quantification in the canine brain. The correlation (R2) between the MRTM2 and the semi-quantitative method using the data between 40 and 60 min was 99.3 % (two-tailed p-value < 0.01). Conclusions The reference tissue models and semi-quantitative method provide a more convenient alternative to invasive arterial sampling models in the evaluation of the SERT of the normal canine brain. The optimal time interval for static scanning is set at 40 to 60 min after tracer injection.
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Affiliation(s)
- Olivia Taylor
- Department of Medical Imaging and Small Animal Orthopedics, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820, Merelbeke, Belgium.
| | - Nick Van Laeken
- Laboratory of Radiopharmacy, Faculty of Pharmaceutical Sciences, Ghent University, Ottergemsesteenweg 460, 9000, Ghent, Belgium.
| | - Filip De Vos
- Laboratory of Radiopharmacy, Faculty of Pharmaceutical Sciences, Ghent University, Ottergemsesteenweg 460, 9000, Ghent, Belgium.
| | - Ingeborgh Polis
- Department of Medicine and Clinical Biology of Small Animals, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820, Merelbeke, Belgium.
| | - Tim Bosmans
- Department of Medicine and Clinical Biology of Small Animals, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820, Merelbeke, Belgium.
| | - Ingeborg Goethals
- Department of Nuclear Medicine, Ghent University Hospital, Ghent University, De Pintelaan 185, 9000, Ghent, Belgium.
| | - Rik Achten
- Department of Radiology, Ghent University Hospital, Ghent University, De Pintelaan 185, 9000, Ghent, Belgium.
| | - Andre Dobbeleir
- Department of Medical Imaging and Small Animal Orthopedics, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820, Merelbeke, Belgium. .,Department of Nuclear Medicine, Ghent University Hospital, Ghent University, De Pintelaan 185, 9000, Ghent, Belgium.
| | - Eva Vandermeulen
- Department of Medical Imaging and Small Animal Orthopedics, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820, Merelbeke, Belgium.
| | - Chris Baeken
- Department of Psychiatry and Medical Psychology, Ghent University Hospital, Ghent University, De Pintelaan 185, 9000, Ghent, Belgium.
| | - Jimmy Saunders
- Department of Medical Imaging and Small Animal Orthopedics, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820, Merelbeke, Belgium.
| | - Kathelijne Peremans
- Department of Medical Imaging and Small Animal Orthopedics, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820, Merelbeke, Belgium.
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Walker M, Ehrlichmann W, Stahlschmidt A, Pichler BJ, Fischer K. In Vivo Evaluation of 11C-DASB for Quantitative SERT Imaging in Rats and Mice. J Nucl Med 2015; 57:115-21. [PMID: 26514178 DOI: 10.2967/jnumed.115.163683] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 10/13/2015] [Indexed: 11/16/2022] Open
Abstract
UNLABELLED Serotonin, or 5-hydroxytryptamine (5-HT), plays a key role in the central nervous system and is involved in many essential neurologic processes such as mood, social behavior, and sleep. The serotonin transporter ligand (11)C-3-amino-4(2-dimethylaminomethyl-phenylsufanyl)-benzonitrile ((11)C-DASB) has been used to determine nondisplaceable binding potential (BPND), which is defined as the quotient of the available receptor density (Bavail) and the apparent equilibrium dissociation rate constant (1/appKD) under in vivo conditions. Because of the increasing number of animal models of human diseases, there is a pressing need to evaluate the applicability of (11)C-DASB to rats and mice. Here, we assessed the feasibility of using (11)C-DASB for quantification of serotonin transporter (SERT) density and affinity in vivo in rats and mice. METHODS Rats and mice underwent 4 PET scans with increasing doses of the unlabeled ligand to calculate Bavail and appKD using the multiple-ligand concentration transporter assay. An additional PET scan was performed to calculate test-retest reproducibility and reliability. BPND was calculated using the simplified reference tissue model, and the results for different reference regions were compared. RESULTS Displaceable binding of (11)C-DASB was found in all brain regions of both rats and mice, with the highest binding being in the thalamus and the lowest in the cerebellum. In rats, displaceable binding was largely reduced in the cerebellar cortex, which in mice was spatially indistinguishable from cerebellar white matter. Use of the cerebellum with fully saturated binding sites as the reference region did not lead to reliable results. Test-retest reproducibility in the thalamus was more than 90% in both mice and rats. In rats, Bavail, appKD, and ED50 were 3.9 ± 0.4 pmol/mL, 2.2 ± 0.4 nM, and 12.0 ± 2.6 nmol/kg, respectively, whereas analysis of the mouse measurements resulted in inaccurate fits due to the high injected tracer mass. CONCLUSION Our data showed that in rats, (11)C-DASB can be used to quantify SERT density with good reproducibility. BPND agreed with the distribution of SERT in the rat brain. It remains difficult to estimate quantitative parameters accurately from mouse measurements because of the high injected tracer mass and underestimation of the binding parameters due to high displaceable binding in the reference region.
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Affiliation(s)
- Michael Walker
- Department of Preclinical Imaging and Radiopharmacy, Werner Siemens Imaging Center, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - Walter Ehrlichmann
- Department of Preclinical Imaging and Radiopharmacy, Werner Siemens Imaging Center, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - Anke Stahlschmidt
- Department of Preclinical Imaging and Radiopharmacy, Werner Siemens Imaging Center, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - Bernd J Pichler
- Department of Preclinical Imaging and Radiopharmacy, Werner Siemens Imaging Center, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - Kristina Fischer
- Department of Preclinical Imaging and Radiopharmacy, Werner Siemens Imaging Center, Eberhard Karls University of Tübingen, Tübingen, Germany
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Spies M, Knudsen GM, Lanzenberger R, Kasper S. The serotonin transporter in psychiatric disorders: insights from PET imaging. Lancet Psychiatry 2015; 2:743-755. [PMID: 26249305 DOI: 10.1016/s2215-0366(15)00232-1] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2015] [Revised: 05/05/2015] [Accepted: 05/07/2015] [Indexed: 01/09/2023]
Abstract
Over the past 20 years, psychotropics affecting the serotonergic system have been used extensively in the treatment of psychiatric disorders. Molecular imaging, in particular PET, has allowed for elucidation of the essential contribution of the serotonin transporter to the pathophysiology of various psychiatric disorders and their treatment. We review studies that use PET to measure cerebral serotonin transporter activity in psychiatric disorders, focusing on major depressive disorder and antidepressant treatment. We also discuss opportunities and limitations in the application of this neuroimaging method in clinical practice. Although results from individual studies diverge, meta-analysis indicates a trend towards reduced serotonin transporter availability in patients with major depressive disorder. Inconsistencies in results might suggest symptom heterogeneity in major depressive disorder and might therefore be relevant for stratification of patients into clinical subsets. PET has enabled the elucidation of mechanisms of response to selective serotonin reuptake inhibitors (SSRIs) and hence provides a basis for rational pharmacological treatment of major depressive disorder. Such imaging studies have also suggested that the pattern of serotonin transporter binding before treatment might predict response to antidepressant treatment, which could potentially be clinically useful in the future. Additionally, this Review discusses PET studies investigating the serotonin transporter in anxiety, obsessive-compulsive disorder, and eating disorders. Few studies have shown changes in serotonin transporter activity in schizophrenia and attention deficit hyperactivity disorder. By showing the scarcity of data in these psychiatric disorders, we highlight the potential for further investigation in this field.
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Affiliation(s)
- Marie Spies
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria
| | - Gitte M Knudsen
- Neurobiology Research Unit, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Rupert Lanzenberger
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria
| | - Siegfried Kasper
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria.
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Finnema SJ, Scheinin M, Shahid M, Lehto J, Borroni E, Bang-Andersen B, Sallinen J, Wong E, Farde L, Halldin C, Grimwood S. Application of cross-species PET imaging to assess neurotransmitter release in brain. Psychopharmacology (Berl) 2015; 232:4129-57. [PMID: 25921033 PMCID: PMC4600473 DOI: 10.1007/s00213-015-3938-6] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 04/09/2015] [Indexed: 01/03/2023]
Abstract
RATIONALE This review attempts to summarize the current status in relation to the use of positron emission tomography (PET) imaging in the assessment of synaptic concentrations of endogenous mediators in the living brain. OBJECTIVES Although PET radioligands are now available for more than 40 CNS targets, at the initiation of the Innovative Medicines Initiative (IMI) "Novel Methods leading to New Medications in Depression and Schizophrenia" (NEWMEDS) in 2009, PET radioligands sensitive to an endogenous neurotransmitter were only validated for dopamine. NEWMEDS work-package 5, "Cross-species and neurochemical imaging (PET) methods for drug discovery", commenced with a focus on developing methods enabling assessment of changes in extracellular concentrations of serotonin and noradrenaline in the brain. RESULTS Sharing the workload across institutions, we utilized in vitro techniques with cells and tissues, in vivo receptor binding and microdialysis techniques in rodents, and in vivo PET imaging in non-human primates and humans. Here, we discuss these efforts and review other recently published reports on the use of radioligands to assess changes in endogenous levels of dopamine, serotonin, noradrenaline, γ-aminobutyric acid, glutamate, acetylcholine, and opioid peptides. The emphasis is on assessment of the availability of appropriate translational tools (PET radioligands, pharmacological challenge agents) and on studies in non-human primates and human subjects, as well as current challenges and future directions. CONCLUSIONS PET imaging directed at investigating changes in endogenous neurochemicals, including the work done in NEWMEDS, have highlighted an opportunity to further extend the capability and application of this technology in drug development.
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Affiliation(s)
- Sjoerd J. Finnema
- />Department of Clinical Neuroscience, Center for Psychiatric Research, Karolinska Institutet, Stockholm, Sweden
| | - Mika Scheinin
- />Department of Pharmacology, Drug Development and Therapeutics, University of Turku, Turku, Finland , />Unit of Clinical Pharmacology, Turku University Hospital, Turku, Finland
| | - Mohammed Shahid
- />Research and Development, Orion Corporation, Orion Pharma, Turku, Finland
| | - Jussi Lehto
- />Department of Pharmacology, Drug Development and Therapeutics, University of Turku, Turku, Finland
| | - Edilio Borroni
- />Neuroscience Department, Hoffman-La Roche, Basel, Switzerland
| | | | - Jukka Sallinen
- />Research and Development, Orion Corporation, Orion Pharma, Turku, Finland
| | - Erik Wong
- />Neuroscience Innovative Medicine Unit, AstraZeneca, Wilmington, DE USA
| | - Lars Farde
- />Department of Clinical Neuroscience, Center for Psychiatric Research, Karolinska Institutet, Stockholm, Sweden , />Translational Science Center at Karolinska Institutet, AstraZeneca, Stockholm, Sweden
| | - Christer Halldin
- />Department of Clinical Neuroscience, Center for Psychiatric Research, Karolinska Institutet, Stockholm, Sweden
| | - Sarah Grimwood
- Neuroscience Research Unit, Pfizer Inc, Cambridge, MA, USA. .,, 610 Main Street, Cambridge, MA, 02139, USA.
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Development of (18)F-labeled radiotracers for neuroreceptor imaging with positron emission tomography. Neurosci Bull 2014; 30:777-811. [PMID: 25172118 DOI: 10.1007/s12264-014-1460-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2014] [Accepted: 06/02/2014] [Indexed: 12/14/2022] Open
Abstract
Positron emission tomography (PET) is an in vivo molecular imaging tool which is widely used in nuclear medicine for early diagnosis and treatment follow-up of many brain diseases. PET uses biomolecules as probes which are labeled with radionuclides of short half-lives, synthesized prior to the imaging studies. These probes are called radiotracers. Fluorine-18 is a radionuclide routinely used in the radiolabeling of neuroreceptor ligands for PET because of its favorable half-life of 109.8 min. The delivery of such radiotracers into the brain provides images of transport, metabolic, and neurotransmission processes on the molecular level. After a short introduction into the principles of PET, this review mainly focuses on the strategy of radiotracer development bridging from basic science to biomedical application. Successful radiotracer design as described here provides molecular probes which not only are useful for imaging of human brain diseases, but also allow molecular neuroreceptor imaging studies in various small-animal models of disease, including genetically-engineered animals. Furthermore, they provide a powerful tool for in vivo pharmacology during the process of pre-clinical drug development to identify new drug targets, to investigate pathophysiology, to discover potential drug candidates, and to evaluate the pharmacokinetics and pharmacodynamics of drugs in vivo.
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Finberg JPM. Update on the pharmacology of selective inhibitors of MAO-A and MAO-B: focus on modulation of CNS monoamine neurotransmitter release. Pharmacol Ther 2014; 143:133-52. [PMID: 24607445 DOI: 10.1016/j.pharmthera.2014.02.010] [Citation(s) in RCA: 178] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Accepted: 02/25/2014] [Indexed: 12/23/2022]
Abstract
Inhibitors of monoamine oxidase (MAO) were initially used in medicine following the discovery of their antidepressant action. Subsequently their ability to potentiate the effects of an indirectly-acting sympathomimetic amine such as tyramine was discovered, leading to their limitation in clinical use, except for cases of treatment-resistant depression. More recently, the understanding that: a) potentiation of indirectly-acting sympathomimetic amines is caused by inhibitors of MAO-A but not by inhibitors of MAO-B, and b) that reversible inhibitors of MAO-A cause minimal tyramine potentiation, has led to their re-introduction to clinical use for treatment of depression (reversible MAO-A inhibitors and new dose form MAO-B inhibitor) and treatment of Parkinson's disease (MAO-B inhibitors). The profound neuroprotective properties of propargyl-based inhibitors of MAO-B in preclinical experiments have drawn attention to the possibility of employing these drugs for their neuroprotective effect in neurodegenerative diseases, and have raised the question of the involvement of the MAO-mediated reaction as a source of reactive free radicals. Despite the long-standing history of MAO inhibitors in medicine, the way in which they affect neuronal release of monoamine neurotransmitters is still poorly understood. In recent years, the detailed chemical structure of MAO-B and MAO-A has become available, providing new possibilities for synthesis of mechanism-based inhibitors. This review describes the latest advances in understanding the way in which MAO inhibitors affect the release of the monoamine neurotransmitters dopamine, noradrenaline and serotonin (5-HT) in the CNS, with an accent on the importance of these effects for the clinical actions of the drugs.
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Dobry Y, Rice T, Sher L. Ecstasy use and serotonin syndrome: a neglected danger to adolescents and young adults prescribed selective serotonin reuptake inhibitors. Int J Adolesc Med Health 2014; 25:193-9. [PMID: 24006318 DOI: 10.1515/ijamh-2013-0052] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Accepted: 04/23/2012] [Indexed: 11/15/2022]
Abstract
BACKGROUND At present, there are scarce clinical and basic lab data concerning the risk of acute serotonin toxicity from selective serotonin reuptake inhibitors (SSRIs) and 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) co-administration. The health care community can strongly benefit from efforts to address the high risks associated with serotonin syndrome from this specific drug combination. OBJECTIVE The aim of this work is to review the risk of serotonin syndrome in adolescents and young adults prescribed with SSRIs and are concurrently using ecstasy. DATA SOURCES An electronic search of the major behavioral science bibliographic databases (Pubmed, PsycINFO, Medline) was conducted to retrieve peer-reviewed articles, which detail the clinical characteristics, biological mechanisms and social implications of SSRIs, MDMA, and their potential synergism in causing serotonin syndrome in the pediatric and young adult population. Search terms included "serotonin syndrome", "ecstasy", "MDMA", "pediatric", and "SSRI". Additional references were incorporated from the bibliographies of these retrieved articles. RESULTS MDMA, in combination with the widely-prescribed SSRI antidepressant class, can lead to rapid, synergistic rise of serotonin (5-HT) concentration in the central nervous system, leading to the acute medical emergency known as serotonin syndrome. This review addresses such complication through an exploration of the theoretical mechanisms and clinical manifestations of this life-threatening pharmacological interaction. CONCLUSION The increasing incidences of recreational ecstasy use and SSRI pharmacotherapy among multiple psychiatric disorders in the adolescent population have made this an overlooked yet increasingly relevant danger, which poses a threat to public health. This can be curbed through further research, as well as greater health care provision and attention from a regulatory body owing.
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Kang HH, Wang CH, Chen HC, Li IH, Cheng CY, Liu RS, Huang WS, Shiue CY, Ma KH. Investigating the effects of noise-induced hearing loss on serotonin transporters in rat brain using 4-[18F]-ADAM/small animal PET. Neuroimage 2013; 75:262-269. [DOI: 10.1016/j.neuroimage.2012.06.049] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2011] [Revised: 06/08/2012] [Accepted: 06/26/2012] [Indexed: 01/10/2023] Open
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Ungersboeck J, Philippe C, Haeusler D, Mitterhauser M, Lanzenberger R, Dudczak R, Wadsak W. Optimization of [11C]DASB-synthesis: vessel-based and flow-through microreactor methods. Appl Radiat Isot 2012; 70:2615-20. [PMID: 22940416 DOI: 10.1016/j.apradiso.2012.08.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Revised: 07/24/2012] [Accepted: 08/02/2012] [Indexed: 11/25/2022]
Abstract
The intention for the present study was to implement a microfluidic set-up for N-(11)C-methylations in a flow-through microreactor device with [(11)C]DASB as model-compound and [(11)C]CH(3)I and [(11)C]CH(3)OTf, respectively, as (11)C-methylation agents. Due to an observed "aging" effect of the (11)C-methylation agents' solution, this goal was not achieved. Nevertheless, based on these observations, the time consumption for the vessel-based routine production of [(11)C]DASB was reduced (34±1 min) and RCY was increased to 45.1±4.6% (EOB; 5.2±0.95 GBq EOS).
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Affiliation(s)
- Johanna Ungersboeck
- Radiochemistry and Biomarker Development Unit, Department of Nuclear Medicine, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna, Austria
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Ho PS, Shih MC, Ma KH, Huang WS, Ho KKJ, Yen CH, Lu RB, Huang SY. Availability of the serotonin transporter in patients with alcohol dependence. World J Biol Psychiatry 2011; 12:134-42. [PMID: 20642399 DOI: 10.3109/15622975.2010.503813] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
OBJECTIVES Evidence has suggested that the serotonin transporter (SERT) plays a role in the pathogenesis of alcohol dependence, anxiety and depression and that polymorphisms of the serotonin-transporter-linked promoter region (5-HTTLPR) may influence the SERT. This study evaluated the differences in SERT availability between healthy controls and alcoholic patients and the impact of 5-HTTLPR polymorphisms on SERT availability. METHODS Eleven healthy controls and 28 alcoholic patients were recruited. SERT availability was measured in vivo with single photon emission computed tomography and (123)I-labelled 2-((2-((dimethyl-amino)methyl)phenyl)thio)-5-iodophenylamine in the midbrain, thalamus and striatum. Each subject was genotyped for the 5-HTTLPR polymorphism. RESULTS Compared to healthy controls, there was a significantly lower availability of SERT in the midbrain among patients with pure alcohol dependence (pure ALC). Of patients with anxiety, depression and alcohol dependence (ANX/DEPALC), the carriers of one L(A) allele showed a significantly higher availability of SERT in the striatum compared to non-L(A) carriers. After Bonferroni correction, these significances vanished. There were no significant differences in SERT availability between controls and ANX/DEP ALC. CONCLUSIONS The results suggest that pure alcoholics may have lower SERT availability in the midbrain; the 5HTTLPR polymorphism may influence SERT availability in ANX/DEP ALC. These findings may serve as a springboard for future large-scale studies.
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Affiliation(s)
- Pei-Shen Ho
- Department of Psychiatry, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
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Abstract
Molecular in vivo neuroimaging techniques can be used to measure regional changes in endogenous neurotransmitters, evoked by challenges that alter synaptic neurotransmitter concentration. This technique has most successfully been applied to the study of endogenous dopamine release using positron emission tomography, but has not yet been adequately extended to other neurotransmitter systems. This review focuses on how the technique has been applied to the study of the 5-hydroxytryptamine (5-HT) system. The principles behind visualising fluctuations in neurotransmitters are introduced, with reference to the dopaminergic system. Studies that aim to image acute, endogenous 5-HT release or depletion at 5-HT receptor targets are summarised, with particular attention to studies in humans. Radiotracers targeting the 5-HT(1A), 5-HT(2A), and 5-HT(4) receptors and the serotonin reuptake transporter have been explored for their sensitivity to 5-HT fluctuations, but with mixed outcomes; tracers for these targets cannot reliably image endogenous 5-HT in humans. Shortcomings in our basic knowledge of the mechanisms underlying changes in binding potential are addressed, and suggestions are made as to how the selection of targets, radiotracers, challenge paradigms, and experimental design might be optimised to improve our chances of successfully imaging endogenous neurotransmitters in the future.
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Wang JL, Deutsch EC, Oya S, Kung HF. FlipADAM: a potential new SPECT imaging agent for the serotonin transporter. Nucl Med Biol 2010; 37:577-86. [DOI: 10.1016/j.nucmedbio.2010.02.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2009] [Revised: 02/09/2010] [Accepted: 02/27/2010] [Indexed: 10/19/2022]
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Genetic variation in HTR2A influences serotonin transporter binding potential as measured using PET and [11C]DASB. Int J Neuropsychopharmacol 2010; 13:715-24. [PMID: 20047709 PMCID: PMC3810474 DOI: 10.1017/s1461145709991027] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
In a previous study we showed that genetic variation in HTR2A, which encodes the serotonin 2A receptor, influenced outcome of citalopram treatment in patients with major depressive disorder. Since chronic administration of citalopram, which selectively and potently inhibits the serotonin transporter (5-HTT), putatively enhances serotonergic transmission, it is conceivable that genetic variation within HTR2A also influences pretreatment 5-HTT function or serotonergic transmission. The present study used positron emission tomography (PET) and the selective 5-HTT ligand, [11C]DASB, to investigate whether the HTR2A marker alleles that predict treatment outcome also predict differences in 5-HTT binding. Brain levels of 5-HTT were assessed in vivo using PET measures of the non-displaceable component of the [11C]DASB binding potential (BPND). DNA from 43 patients and healthy volunteers, all unmedicated, was genotyped with 14 single nucleotide polymorphisms located within or around HTR2A. Allelic association with BPND was assessed in eight brain regions, with covariates to control for race and ethnicity. We detected allelic association between [11C]DASB BPND in thalamus and three markers in a region spanning the 3' untranslated region and second intron of HTR2A (rs7333412, p=0.000045; rs7997012, p=0.000086; rs977003, p=0.000069). The association signal at rs7333412 remained significant (p<0.05) after applying corrections for multiple testing via permutation. Genetic variation in HTR2A that was previously associated with citalopram treatment outcome was also associated with thalamic 5-HTT binding. While further work is needed to identify the actual functional genetic variants involved, these results suggest that a relationship exists between genetic variation in HTR2A and either 5-HTT expression or central serotonergic transmission that influences the therapeutic response to 5-HTT inhibition in major depression.
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Yokoyama C, Yamanaka H, Onoe K, Kawasaki A, Nagata H, Shirakami K, Doi H, Onoe H. Mapping of serotonin transporters by positron emission tomography with [11c]DASB in conscious common marmosets: Comparison with rhesus monkeys. Synapse 2010; 64:594-601. [DOI: 10.1002/syn.20766] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Hammoud DA, Endres CJ, Hammond E, Uzuner O, Brown A, Nath A, Kaplin AI, Pomper MG. Imaging serotonergic transmission with [11C]DASB-PET in depressed and non-depressed patients infected with HIV. Neuroimage 2009; 49:2588-95. [PMID: 19853044 DOI: 10.1016/j.neuroimage.2009.10.037] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2009] [Revised: 09/10/2009] [Accepted: 10/13/2009] [Indexed: 11/18/2022] Open
Abstract
INTRODUCTION Site-selective imaging can provide significant insight into the mechanism of HIV-associated neurological disease. The goal of this study was to evaluate the involvement of serotonergic transmission in HIV-associated depression using [(11)C]DASB, a serotonin transporter (5-HTT)-specific radiopharmaceutical for positron emission tomography (PET). METHODS Nine depressed HIV+ subjects (HIV-D), 9 non-depressed HIV+ subjects (HIV-ND) and 7 healthy controls (HC) underwent an MRI scan and a [(11)C]DASB-PET scan. The outcome measure was 5-HTT binding potential normalized to non-displaceable tissue radioligand (BP(ND)). RESULTS HIV-ND subjects had lower mean regional 5-HTT BP(ND) estimates across regions compared to HC, while HIV-D subjects demonstrated higher mean regional binding values than HIV-ND subjects in most regions. Prior to correction for the false discovery rate, HIV-ND had significantly lower BP(ND) values compared to HC subjects in two regions (insula and anterior cingulate) and all HIV+ patients had significantly lower binding than HC in all regions except for the midbrain, thalamus and pons. After correction for the false discovery rate, only the insula showed significantly lower binding in HIV+ subjects compared to HC (P<0.0045). Despite a significant difference in the duration of illness between the HIV-D and HIV-ND groups, there was no definite correlation between the duration of illness and BP(ND). CONCLUSION Lower [(11)C]DASB binding in HIV+ patients compared to HC may reflect serotonergic neuronal loss as a component of generalized HIV-associated neurodegeneration. Higher mean regional BP(ND) values in HIV-D compared to HIV-ND subjects could reflect increased density of 5-HTT, leading to increased clearance of serotonin from the synapse, which could account, in part, for symptoms of depression. The lack of correlation between duration of illness and binding argues against these findings being the result of differential neurodegeneration only. Our findings suggest a possible role for dysregulated serotonergic transmission in HIV-associated depression.
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Affiliation(s)
- Dima A Hammoud
- Radiology and Imaging Sciences, National Institutes of Health/Clinical Center, Bethesda, MD, USA
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Solbach C, Reischl G, Machulla HJ. Determination of reaction parameters for the synthesis of the serotonin transporter ligand [11C]DASB: Application to a remotely controlled high yield synthesis. RADIOCHIM ACTA 2009. [DOI: 10.1524/ract.92.4.341.35597] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Abstract
The synthesis of [11C]DASB is known to be performed by reacting the demethyl-DASB precursor with [11C]methyl iodide but the necessary reaction parameters had hitherto not been determined. In this work the dependence of the labelling yield on reaction temperature, reaction time, precursor concentration and type of solvent was investigated. Best results were found when methylation was carried out at 100 °C within 2 min using 4 mg/ml demethyl precursor in DMSO. With respect to [11C]methyl iodide a radiochemical yield of 74%±3% [11C]DASB was achieved. In addition, the synthesis was transferred to a remotely controlled module. A carbon-11 production for 1 h at 50 μA resulted in 3800-4300 MBq [11C]DASB with a specific activity of 152-211 GBq/μmol (4.1-5.7 Ci/μmol) (EOS) and a radiochemical purity of >95% in a sterile solution ready for injection. The total synthesis time was 45 min after EOB.
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Utility of small-animal positron emission tomographic imaging of rats for preclinical development of drugs acting on the serotonin transporter. Int J Neuropsychopharmacol 2009; 12:1021-32. [PMID: 19236731 DOI: 10.1017/s1461145709000042] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Visualization of neurotransmission components in living small animals using positron emission tomography (PET) has the potential of contributing to the preclinical development of neuroactive drugs, although it is yet to be examined whether quantitative animal PET data on candidate compounds can be extrapolated to humans. Here, we investigated the comparability of the occupancies of serotonin transporter (5-HTT) by therapeutic agents in rat PET studies with our predetermined data from ex- vivo animal experiments and clinical PET scans. Rats were treated with varying doses of fluvoxamine and a newly developed compound, (2S)-1-[4-(3,4-dichlorophenyl) piperidin-1-yl]-3-[2-(5-methyl-1,3,4-oxadiazol-2-yl)benzo[b]furan-4-yloxy]propan-2-ol monohydrochloride (Wf-516), and underwent PET scans with [11C]3-amino-4-(2-dimethylaminomethyl-phenylsulfanyl)-benzonitrile ([11C]DASB), a selective radioligand for in-vivo quantification of 5-HTT. PET images indicated a reduction of [11C]DASB binding to 5-HTT as a function of the doses and/or plasma concentrations of fluvoxamine and Wf-516. The doses of these drugs at half-maximal effect (15.2 mg/kg and 3.1 mg/kg, respectively), determined that using binding potentials for [11C]DASB, were comparable to those estimated by our previous ex-vivo measurements in rats (4.5 mg/kg and 1.1 mg/kg, respectively), as there was only a 3-fold difference between these results. Moreover, the plasma concentration of fluvoxamine needed for 50% occupancy of central 5-HTT (6.1 ng/ml) was almost equivalent to the value determined in human PET studies (4.6 ng/ml). These findings support the view that the conjunctive use of small-animal PET and [11C]DASB facilitates a quantitative comparison of in-development drugs targeting 5-HTT with established inhibitors and a predictive estimation of their plasma concentrations exerting therapeutic effects in humans.
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Wang JL, Parhi AK, Oya S, Lieberman B, Kung HF. In Vivo Characterization of a Series of 18F-Diaryl Sulfides (18F-2-(2′-((Dimethylamino)Methyl)-4′-(Fluoroalkoxy)Phenylthio)Benzenamine) for PET Imaging of the Serotonin Transporter. J Nucl Med 2009; 50:1509-17. [DOI: 10.2967/jnumed.108.060723] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Study on the neuroprotective effect of fluoxetine against MDMA-induced neurotoxicity on the serotonin transporter in rat brain using micro-PET. Neuroimage 2009; 49:1259-70. [PMID: 19682588 DOI: 10.1016/j.neuroimage.2009.07.072] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2009] [Revised: 07/15/2009] [Accepted: 07/30/2009] [Indexed: 11/20/2022] Open
Abstract
3, 4-Methylenedioxymethamphetamine (MDMA, "ecstasy") has toxic effects on serotonergic neurons in the brain. Our aim was to determine whether N,N-dimethyl-2-(2-amino-4-[(18)F]-fluorophenylthio) benzylamine (4-[(18)F]-ADAM; a serotonin transporter imaging agent) and micropositron emission tomography (micro-PET) can be used to examine in vivo the effect of fluoxetine on MDMA-induced loss of serotonin transporters in rat brain. Male Sprague-Dawley rats were injected with fluoxetine [1 dose, 5 mg/kg, subcutaneously (s.c.)] followed by MDMA (twice a day for 4 consecutive days, 10 mg/kg, s.c.). Micro-PET with 4-[(18)F]-ADAM was performed on days 4, 10, 17, 24, and 31. In addition, the time course of occupancy by fluoxetine at 4-[(18)F]-ADAM sites was measured. Specific 4-[(18)F]-ADAM uptake ratios (SURs) were calculated from the micro-PET imaging data for various brain regions. Immunohistochemistry was performed 7 days after the last micro-PET scan. From day 4 to day 31, SURs were markedly decreased (by approximately 55-75% compared to control values) in all brain regions in MDMA-treated rats. The effect of MDMA was markedly attenuated (approximately 30-50%) by fluoxetine. The fluoxetine-induced decrease in uptake in different brain regions was 40-75% at 90-min postinjection, and this decrease returned to baseline values in most brain regions by day 31. The distribution and intensity of serotonin transporter (SERT) immunostaining in the brain paralleled the PET imaging results, suggesting that a single dose of fluoxetine provides long-lasting protection against MDMA-induced loss of SERT and that such neuroprotection is detectable in vivo by 4-[(18)F]-ADAM micro-PET.
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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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Demaree HA, Pu J, Jesberger J, Feeny N, Jeng L, Everhart DE, Duerk J, Tkach J. 5HTTLPR predicts left fusiform gyrus activation to positive emotional stimuli. Magn Reson Imaging 2009; 27:441-8. [PMID: 18849132 PMCID: PMC3087948 DOI: 10.1016/j.mri.2008.08.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2008] [Revised: 08/19/2008] [Accepted: 08/22/2008] [Indexed: 11/28/2022]
Abstract
This study was designed to replicate and extend past research examining the impact of the serotonin transporter gene-linked polymorphic region (5HTTLPR) on neural activation during emotional processing. Six women with at least one short allele were compared to six age-matched women with long/long alleles of the 5HTTLPR. Participants were shown 36 positive and 36 negative slides from the International Affective Picture Set, while functional images were acquired using a 4-T magnetic resonance imaging scanner. Although we were unable to replicate past research demonstrating relatively increased amygdala activation among individuals with an "s" allele to negative stimuli, women with an s allele evidenced decreased left fusiform gyrus activation to positive emotional stimuli (as expected). We suggest that women with a short allele may be either less attentive or less "expert" with regard to positive emotional stimuli, and ideas for future research are presented.
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Affiliation(s)
- Heath A Demaree
- Department of Psychology, Case Western Reserve University, Cleveland, OH 44106-7123, USA.
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Ma KH, Huang WS, Kuo YY, Peng CJ, Liou NH, Liu RS, Hwang JJ, Liu JC, Chen HJ, Shiue CY. Validation of 4-[18F]-ADAM as a SERT imaging agent using micro-PET and autoradiography. Neuroimage 2009; 45:687-93. [DOI: 10.1016/j.neuroimage.2008.12.060] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2008] [Revised: 12/04/2008] [Accepted: 12/23/2008] [Indexed: 11/24/2022] Open
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Moulin-Sallanon M, Charnay Y, Ginovart N, Perret P, Lanfumey L, Hamon M, Hen R, Fagret D, Ibáñez V, Millet P. Acute and chronic effects of citalopram on 5-HT1A receptor-labeling by [18F]MPPF and -coupling to receptors-G proteins. Synapse 2009; 63:106-16. [PMID: 19016488 DOI: 10.1002/syn.20588] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Selective serotonin reuptake inhibitors take several weeks to produce their maximal therapeutic antidepressant effect. This delay has been attributed to the gradual desensitization of somatodendritic serotonin 5-HT(1A) autoreceptors. We evaluated adaptive changes of 5-HT(1A) receptors after acute and chronic citalopram challenges in rat. Small animal positron emission tomography trial and quantitative ex vivo autoradiography studies using [(18)F]MPPF were employed, as well as in vitro 8-OH-DPAT-stimulated [(35)S]-GTPgammaS binding assay. Additionally, 5-HT(1A) receptor knock-out mice were used to assess the specificity of [(18)F]MPPF. Acute treatment with citalopram did not alter [(18)F]MPPF binding in dorsal raphe nucleus (DR), frontal cortex, or hippocampus. The absence of [(18)F]MPPF binding in the brain of 5-HT(1A) knock-out mice demonstrates the specificity of MPPF for 5-HT(1A) receptor brain imaging, but the high affinity of [(18)F]MPPF compared to 5-HT suggests that it would only be displaced by dramatic increases in extracellular 5-HT. Chronic citalopram did not modify 5-HT(1A) receptor density in any of the brain regions studied. In addition, this treatment did not modify 8-OH-DPAT-stimulated [(35)S]-GTPgammaS binding in DR, although a significant increase was observed in frontal cortex and hippocampus. [(18)F]MPPF appears to be an efficient radioligand to quantify specifically 5-HT(1A) receptor density in brain imaging. The delayed therapeutic efficacy of citalopram did not appear to be linked to either a downregulation of 5-HT(1A) receptors or to a 5-HT(1A) receptor-G protein decoupling process in serotonergic neurons, but to increased functional sensitivity of postsynaptic 5-HT(1A) receptors.
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Molecular Imaging in Neurology and Psychiatry. Mol Imaging 2009. [DOI: 10.1007/978-3-540-76735-0_16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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2-(2'-((Dimethylamino)methyl)-4'-(3-[(18)F]fluoropropoxy)-phenylthio)benzenamine for positron emission tomography imaging of serotonin transporters. Nucl Med Biol 2008; 35:447-58. [PMID: 18482682 DOI: 10.1016/j.nucmedbio.2008.02.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2007] [Revised: 02/06/2008] [Accepted: 02/14/2008] [Indexed: 11/21/2022]
Abstract
INTRODUCTION A new (18)F ligand, 2-(2'-((dimethylamino)methyl)-4'-(3-[(18)F]fluoropropoxy)-phenylthio)benzenamine ([(18)F]1), for positron emission tomography (PET) imaging of serotonin transporters (SERT) was evaluated. METHODS Binding affinity was determined through in vitro binding assays with LLC-PK1 cells overexpressing SERT, NET or DAT (LLC-SERT, LLC-NET and LLC-DAT) and with rat cortical homogenates. Localization and selectivity of [(18)F]1 binding in vivo were evaluated by biodistribution, autoradiography and A-PET imaging studies in rats. RESULTS This compound displayed excellent binding affinity for SERT in vitro with K(i)=0.33 and 0.24 nM in LLC-SERT and rat cortical homogenates, respectively. Biodistribution studies with [(18)F]1 showed good brain uptake (1.61% dose/g at 2 min postinjection), high uptake into the hypothalamus (1.22% dose/g at 30 min) and a high target-to-nontarget (hypothalamus to cerebellum) ratio of 9.66 at 180 min postinjection. Pretreatment with a SERT selective inhibitor considerably inhibited [(18)F]1 binding in biodistribution studies. Ex vivo autoradiography reveals [(18)F]1 localization to brain regions with high SERT density, and this binding was blocked by pretreatment with SERT selective inhibitors. Small animal PET (A-PET) imaging in rats provided clear images of tracer localization in the thalamus, midbrain and striatum. In A-PET chasing experiments, injecting a SERT selective inhibitor 75 min post-tracer injection causes a dramatic reduction in regional radioactivity and the target-to-nontarget ratio. CONCLUSION The results of the biological studies and the ease of radiosynthesis with moderately good radiochemical yield (RCY=10-35%) make [(18)F]1 an excellent candidate for SERT PET imaging.
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MicroPET imaging of 5-HT 1A receptors in rat brain: a test-retest [18F]MPPF study. Eur J Nucl Med Mol Imaging 2008; 36:53-62. [PMID: 18704404 DOI: 10.1007/s00259-008-0891-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2008] [Accepted: 07/11/2008] [Indexed: 10/21/2022]
Abstract
PURPOSE Earlier studies have shown that positron emission tomography (PET) imaging with the radioligand [(18)F]MPPF allows for measuring the binding potential of serotonin 5-hydroxytryptamine(1A) (5-HT(1A)) receptors in different regions of animal and human brain, including that of 5-HT(1A) autoreceptors in the raphe nuclei. In the present study, we sought to determine if such data could be obtained in rat, with a microPET (R4, Concorde Microsystems). METHODS Scans from isoflurane-anaesthetised rats (n = 18, including six test-retest) were co-registered with magnetic resonance imaging data, and binding potential, blood to plasma ratio and radiotracer efflux were estimated according to a simplified reference tissue model. RESULTS Values of binding potential for hippocampus (1.2), entorhinal cortex (1.1), septum (1.1), medial prefrontal cortex (1.0), amygdala (0.8), raphe nuclei (0.6), paraventricular hypothalamic nucleus (0.5) and raphe obscurus (0.5) were comparable to those previously measured with PET in cats, non-human primates or humans. Test-retest variability was in the order of 10% in the larger brain regions (hippocampus, medial prefrontal and entorhinal cortex) and less than 20% in small nuclei such as the septum and the paraventricular hypothalamic, basolateral amygdaloid and raphe nuclei. CONCLUSIONS MicroPET brain imaging of 5-HT(1A) receptors with [(18)F]MPPF thus represents a promising avenue for investigating 5-HT(1A) receptor function in rat.
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Abstract
The recent increase in radioligands available for neuroimaging major depressive disorder has led to advancements in our understanding of the pathophysiology of this illness and improved antidepressant development. Major depressive disorder can be defined as an illness of recurrent major depressive episodes of persistently low mood, dysregulated sleep, appetite and weight, anhedonia, cognitive impairment, and suicidality. The main target sites investigated with radioligand neuroimaging include receptor sites that regulate in response to lowered monoamine levels, targets related to removal of monoamines, uptake of ligands related to regional brain function, and target sites of antidepressants.
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Affiliation(s)
- Jeffrey H Meyer
- Department of Psychiatry, University of Toronto, Toronto, Canada.
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Markus CR. Dietary amino acids and brain serotonin function; implications for stress-related affective changes. Neuromolecular Med 2008; 10:247-58. [PMID: 18516508 DOI: 10.1007/s12017-008-8039-9] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2008] [Accepted: 05/06/2008] [Indexed: 11/24/2022]
Abstract
Stress-related mood deterioration and affective disorders, such as depression, are among the leading causes of disease burden throughout the world, and are associated with severe medical consequences and mortality. Research has shown the involvement of dysfunctional brain serotonin (5-HT) biochemistry as a vulnerable biological factor in the onset of mood disturbances. Since the production of brain serotonin is limited by the availability of its plasma dietary amino acid precursor tryptophan, different foods and dietary amino acids that influence tryptophan availability are thought to alter affective behavior by changing brain 5-HT synthesis. Most dietary manipulation studies, however, reveal only modest affective changes, and note that these particularly occur in stress-prone or affected (sub-clinical) subjects. The current paper briefly summarizes evidence for the involvement of diminished brain serotonin function in affective disorders, discusses how this can be assessed and influenced by dietary manipulation procedures, and also notes how beneficial effects of dietary brain serotonin manipulation on affective behavior may be mediated by stress-induced brain serotonin vulnerability.
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Affiliation(s)
- C Rob Markus
- Department of Neuropsychology and Psychopharmacology, University of Maastricht, P.O. Box 6200, Maastricht, MD, The Netherlands.
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Geldof M, Freijer JI, van Beijsterveldt L, Langlois X, Danhof M. Pharmacokinetic-pharmacodynamic modelling of fluvoxamine 5-HT transporter occupancy in rat frontal cortex. Br J Pharmacol 2008; 154:1369-78. [PMID: 18493251 DOI: 10.1038/bjp.2008.179] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND AND PURPOSE The pharmacokinetic-pharmacodynamic (PK-PD) correlation of fluvoxamine 5-HT transporter (SERT) occupancy was determined in rat frontal cortex ex vivo. EXPERIMENTAL APPROACH Rats (n=47) with permanent arterial and venous cannulas received a 30 min intravenous infusion of fluvoxamine (1 or 7.3 mg kg(-1)). At various time points after dosing, brains were collected for determination of fluvoxamine concentration and SERT occupancy. In addition, the time course of fluvoxamine concentration in plasma was determined up to the time of brain collection. In a separate study (n=26), the time course of fluvoxamine concentration in brain extracellular fluid (ECF) and plasma was determined. The results of the investigations were interpreted by nonlinear mixed effects modeling. KEY RESULTS Highest SERT occupancy was reached at the first time point (10 or 15 min) and maintained for 1.5 and 7 h after 1 and 7.3 mg kg(-1), respectively. Thereafter, SERT occupancy decreased linearly at a rate of 8% h(-1). SERT occupancy could be directly related to plasma, brain ECF and brain tissue concentrations by a hyperbolic function (Bmax model). Maximal SERT occupancy (Bmax) was 95%. Estimated concentrations at half-maximal SERT occupancy (EC50) in plasma, ECF and brain tissue were 0.48, 0.22 and 14.8 ng mL(-1) respectively. The minimum value of the objective function decreased 12 points for ECF and brain tissue concentrations relative to plasma (P<0.01), presumably as a result of nonlinear brain distribution. CONCLUSIONS AND IMPLICATIONS The proposed PK-PD model constitutes a useful basis for prediction of the time course of ex vivo SERT occupancy in behavioural studies with selective serotonin reuptake inhibitors.
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Affiliation(s)
- M Geldof
- Department of Pharmacology, Leiden-Amsterdam Center for Drug Research, Leiden University, Leiden, The Netherlands
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Sharma S, Ebadi M. SPECT neuroimaging in translational research of CNS disorders. Neurochem Int 2008; 52:352-62. [PMID: 17904694 DOI: 10.1016/j.neuint.2007.08.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2007] [Revised: 07/14/2007] [Accepted: 08/09/2007] [Indexed: 10/22/2022]
Abstract
High resolution SPECT imaging is an emerging field and there are only limited studies as yet available in this direction. Still there is continuous effort to achieve better spatial and temporal resolution in order to obtain detailed structural and functional information of different brain regions in small experimental animals. Recently, SPECT imaging system has been used to perform in vivo imaging using specific radioligands to further elucidate the role of dopaminergic, serotonergic, and cholinergic neurotransmission in relation to regional cerebral blood flow in various human CNS disorders and in gene-manipulated mouse models of neurodegeneration. Although in vivo and non-invasive translational research can be performed by high-resolution microPET imaging system, its limited spatial resolution restricts detailed anatomical and functional information of different brain regions involved in disease process. Recently developed NanoSPECT/CT imaging system has a better spatial resolution hence can be used to correlate and confirm microPET imaging data and determine the precise structural and functional anatomy of CNS disorders and their remission. Moreover SPECT imaging system reduces the cost and number of animals and provides detailed information of CNS disorders at the cellular, molecular and genetic level. Furthermore, SPECT system is economical, provides less radiation burden, and can be used to study bio-distribution of newly synthesized radioligands with increased target to non-target ratios, quality control, and clinical applications. It is envisaged that high-resolution SPECT imaging system will further improve in vivo non-invasive translational research on CNS disorders of unknown etiopathogenesis and their treatment in future.
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Affiliation(s)
- Sushil Sharma
- Cyclotron & Positron Imaging Research Laboratory, Center of Excellence in Neurosciences, University of North Dakota School of Medicine & Health Sciences, Grand Forks, ND 58203, USA.
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Banks ML, Czoty PW, Gage HD, Bounds MC, Garg PK, Garg S, Nader MA. Effects of cocaine and MDMA self-administration on serotonin transporter availability in monkeys. Neuropsychopharmacology 2008; 33:219-25. [PMID: 17443127 PMCID: PMC2167630 DOI: 10.1038/sj.npp.1301420] [Citation(s) in RCA: 38] [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] [Indexed: 11/09/2022]
Abstract
Although serotonin (5-HT) can interact with dopamine (DA) systems to modulate the subjective and reinforcing effects of psychostimulants such as cocaine and 3,4-methyldioxymethamphetamine (MDMA, ecstasy), the long-term effects of exposure to psychostimulants on brain 5-HT systems are not well characterized. The present study assessed 5-HT transporter (SERT) availability using positron emission tomography (PET) in rhesus monkeys with the SERT-specific radioligand [(11)C]3-amino-4-(2-dimethylaminomethyl-phenylsulfanyl)-benzonitrile (DASB). SERT availability was assessed in regions of interest including the caudate nucleus, putamen, anterior cingulate cortex, and cerebellum. [(11)C]DASB distribution volume ratios (DVRs) were calculated using the cerebellum as the reference region. DVRs were calculated in control monkeys and in cocaine or MDMA self-administering monkeys approximately 24 h after the last self-administration (SA) session. SERT availability did not differ between monkeys with a history of MDMA SA and control monkeys in any region examined. In contrast, monkeys with a history of cocaine SA showed significantly higher levels of SERT availability in the caudate nucleus and putamen compared to control subjects. These results suggest that chronic SA of cocaine, but not MDMA, leads to alterations in serotonergic function in brain areas relevant to drug abuse. The higher level of SERT availability in cocaine-experienced monkeys may lead to a reduced inhibitory tone of 5-HT on the DA system, which may explain, in part, differences in the abuse liability between cocaine and MDMA.
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Affiliation(s)
- Matthew L Banks
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC 27157-1083, USA
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Parhi AK, Wang JL, Oya S, Choi SR, Kung MP, Kung HF. 2-(2'-((dimethylamino)methyl)-4'-(fluoroalkoxy)-phenylthio)benzenamine derivatives as serotonin transporter imaging agents. J Med Chem 2007; 50:6673-84. [PMID: 18052090 DOI: 10.1021/jm070685e] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A novel series of ligands with substitutions at the 5-position on phenyl ring A and at the 4'-position on phenyl ring B of 2-(2'-((dimethylamino)methyl)-4'-(fluoroalkoxy)phenylthio)benzenamine (4'-2-fluoroethoxy derivatives 28-31 and 4'-3-fluoropropoxy derivatives 40-42) were prepared and tested as serotonin transporter (SERT) imaging agents. The new ligands displayed high binding affinities to SERT (Ki ranging from 0.03 to 1.4 nM). The corresponding 18F labeled compounds, which can be prepared readily, showed excellent brain uptake and retention after iv injection in rats. The hypothalamus region showed high uptake values between 0.74% and 2.2% dose/g at 120 min after iv injection. Significantly, the hypothalamus to cerebellum ratios (target to nontarget ratios) at 120 min were 7.8 and 7.7 for [18F]28 and [18F]40, respectively. The selective uptake and retention in the hypothalamus, which has a high concentration of SERT binding sites, demonstrated that [18F]28 and [18F]40 are promising positron emission computed tomography imaging agents for mapping SERT binding sites in the brain.
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Affiliation(s)
- Ajit K Parhi
- Department of Radiology, University of Pennsylvania, Philadelphia 19104, USA
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Yamamoto S, Onoe H, Tsukada H, Watanabe Y. Effects of increased endogenous serotonin on the in vivo binding of [11C]DASB to serotonin transporters in conscious monkey brain. Synapse 2007; 61:724-31. [PMID: 17559093 DOI: 10.1002/syn.20422] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Using a combination of positron emission tomography (PET) and the microdialysis technique, the effects of increased endogenous serotonin (5-hydroxytryptamine; 5-HT) on the binding of [(11)C]DASB to 5-HT transporters (5-HTT) were investigated in the conscious monkey brain. Five rhesus monkeys (Macaca mulatta) were scanned with [(11)C]DASB under the control condition and the increased endogenous 5-HT condition, in which 5-hydroxy-L-tryptophan (5-HTP) was administered (20 mg/kg, i.v.) before the PET scan. Compared with the control scan, the 5-HTP administration significantly decreased the binding potential (BP) (BP = B(max)/K(d)) of [(11)C]DASB in several brain regions. The mean % decrease of BP was biggest in the caudate and putamen. Two monkeys were scanned with [(11)C]5-HTP to assess the amino acid decarboxylase (AADC) activity in the brain, resulting in the high activity in the caudate and putamen. Microdialysis measurements showed that although 5-HTP administration (20 mg/kg, i.v.) increased the extracellular 5-HT levels in both the prefrontal cortex and caudate, the increase of the 5-HT level in the caudate was 27 times higher than that in the prefrontal cortex. These results suggest that the caudate and putamen, both of which show high AADC activity, convert 5-HTP to 5-HT at a high rate, and the increased 5-HT competes with [(11)C]DASB for the 5-HTT.
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Affiliation(s)
- Shigeyuki Yamamoto
- Department of Physiology, Osaka City University Graduate School of Medicine, Abeno-ku, Osaka, Japan.
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Voineskos AN, Wilson AA, Boovariwala A, Sagrati S, Houle S, Rusjan P, Sokolov S, Spencer EP, Ginovart N, Meyer JH. Serotonin transporter occupancy of high-dose selective serotonin reuptake inhibitors during major depressive disorder measured with [11C]DASB positron emission tomography. Psychopharmacology (Berl) 2007; 193:539-45. [PMID: 17497139 DOI: 10.1007/s00213-007-0806-z] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2006] [Accepted: 04/13/2007] [Indexed: 10/23/2022]
Abstract
RATIONALE Previous work has shown 80% serotonin transporter (5-HTT) occupancy to be a consistent finding at the minimum therapeutic dose during selective serotonin reuptake inhibitor (SSRI) treatment. [(11)C]N,N-dimethyl-2-(2-amino-4-cyanophenylthio) benzylamine positron emission tomography ([(11)C]DASB PET) is currently the best method available to quantify 5-HTT occupancy in humans. OBJECTIVES The purpose of the present study is to determine 5-HTT occupancy during high dose SSRI treatment using [(11)C]DASB PET. MATERIALS AND METHODS Twelve healthy subjects and 12 subjects with major depressive disorder completed the protocol. Depressed subjects received one [(11)C]DASB PET scan after a minimum of 4 weeks treatment at high doses of venlafaxine, sertraline, or citalopram. Baseline 5-HTT binding potential (BP) was taken as the average 5-HTT BP of the 12 healthy subjects. RESULTS Mean striatal 5-HTT occupancy for each antidepressant group was approximately 85% at high therapeutic dose. This was significantly greater than 80% (one-sample t test; p < 0.04, venlafaxine group; p < 0.02, sertraline group; p < 0.01, citalopram group) for each high dose antidepressant group. CONCLUSIONS Significantly greater 5-HTT blockade at high dose provides a rationale for raising the dose from the minimum therapeutic dose in specific clinical circumstances. It is likely that 15% unoccupied 5-HTT remains, which should be addressed in future drug development.
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Affiliation(s)
- Aristotle N Voineskos
- Clarke site, Centre for Addiction and Mental Health, Department of Psychiatry, University of Toronto, ON, M5T 1R8, Canada
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Lundquist P, Roman M, Syvänen S, Hartvig P, Blomquist G, Hammarlund-Udenaes M, Långström B. Effect on [11C]DASB binding after tranylcypromine-induced increase in serotonin concentration: positron emission tomography studies in monkeys and rats. Synapse 2007; 61:440-9. [PMID: 17372973 DOI: 10.1002/syn.20382] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Several research groups have demonstrated that under specific conditions, in vivo neuroreceptor binding techniques can be used to measure acute changes in the concentrations of endogenous transmitters in the vicinity of neuroreceptors. The aim of this study was to investigate whether [(11)C]-3-amino-4-(2-dimethylaminomethyl-phenylsulfanyl)-benzonitrile ([(11)C]DASB) binding to the plasma membrane serotonin transporter (SERT) in the rhesus monkey and rat brain decreased after a pharmacologically-induced increase in the interstitial serotonin (5HT) concentration. Three rhesus monkeys were given repeated single boluses of [(11)C]DASB in sequential positron emission tomography (PET) experiments. Rats were given the tracer as a bolus dose plus a constant infusion. In vivo binding in both models was studied before and after presumably having increased interstitial 5HT concentrations using tranylcypromine (TCP), which inhibits the enzyme (monoamine oxidase, MAO), that degrades 5HT. The rat brain tissue was analyzed using high-performance liquid chromatography (HPLC) to determine the proportion of the PET signal comprising unchanged [(11)C]DASB. The binding of [(11)C]DASB in the thalamus decreased in both rhesus monkeys and rats after TCP administration. The possibility of using [(11)C]DASB as a tool for monitoring changes in endogenous serotonin concentrations merits further investigation.
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Affiliation(s)
- Pinelopi Lundquist
- Division of Pharmacokinetics and Drug Therapy, Department of Pharmaceutical Biosciences, Uppsala University, SE-751 24 Uppsala, Sweden.
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Arbouw MEL, Movig KLL, Neef C, Guchelaar HJ, Egberts TCG. Influence of initial use of serotonergic antidepressants on antiparkinsonian drug use in levodopa-using patients. Eur J Clin Pharmacol 2007; 63:181-7. [PMID: 17200834 DOI: 10.1007/s00228-006-0233-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2006] [Accepted: 10/25/2006] [Indexed: 11/29/2022]
Abstract
OBJECTIVE To assess whether there is an association between initial use of serotonergic antidepressants and changes in antiparkinsonian drug treatment. METHODS A retrospective cohort study was performed with the PHARMO record linkage system. All patients from 1994 until 2004 of 40 years or older who were first time users of an antidepressant and who had used a levodopa-containing drug at least 180 days before initiation of the antidepressant were included. The maximum follow-up time was 180 days. The first change in antiparkinsonian drug treatment, defined as an increase in the daily dosage of any antiparkinsonian drug, the start of a new antiparkinsonian drug or a change in the dosage form during the follow-up period, was taken as an endpoint. Antidepressants were classified in two ways: according to their class [selective serotonin reuptake inhibitors (SSRI), tricyclic antidepressants (TCA) or other antidepressants] or by the extent of their inhibition of serotonin reuptake (high, intermediate or low). RESULTS A total of 221 patients was included in our study. The adjusted hazard ratio for a change in antiparkinsonian drug treatment was 0.7 (95% CI 0.3-1.5) comparing SSRI with TCA users, and it was 0.9 (95% CI 0.4-2.1) comparing users of other antidepressants with TCA users. The adjusted hazard ratio for a change in antiparkinsonian drug treatment was 0.6 (95% CI 0.3-1.4) comparing users of antidepressants with high versus low extent of inhibition of serotonin reuptake, and it was 0.7 (95% CI 0.3-1.4) comparing users of antidepressants with intermediate versus low extent of inhibition of serotonin reuptake. CONCLUSION Based on these observations, we found no evidence to be more cautious using SSRIs or serotonergic antidepressants compared to other antidepressants in patients with Parkinson's disease.
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Affiliation(s)
- Maurits E L Arbouw
- Faculty of Science, Division of Pharmacoepidemiology and Pharmacotherapy, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands
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Wyneken U, Sandoval M, Sandoval S, Jorquera F, González I, Vargas F, Falcon R, Monari M, Orrego F. Clinically relevant doses of fluoxetine and reboxetine induce changes in the TrkB content of central excitatory synapses. Neuropsychopharmacology 2006; 31:2415-23. [PMID: 16554746 DOI: 10.1038/sj.npp.1301052] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We have studied the effect of low doses of two widely used antidepressants, fluoxetine (Flx) and reboxetine (Rbx), on excitatory synapses of rat brain cortex and hippocampus. After 15 days of Flx treatment (0.67 mg/kg/day), its plasma level was 20.7+/-5.6 ng/ml. Analysis of postsynaptic densities (PSDs) by immunoblotting revealed no changes in the glutamate receptor subunits GluR1, NR1, NR2A/B, mGluR1alpha nor in the neurotrophin receptor p75(NTR). However, the brain-derived neurotrophic factor (BDNF) receptor TrkB decreased by 42.8+/-6%, and remained decreased after 6 weeks of treatment. The BDNF and TrkB content in homogenates of cortex and hippocampus began to rise at 9 and 15 days, respectively, and remained high for up to 6 weeks. Similar results were obtained following chronic Rbx administration at 0.128 mg/kg/day. We propose that BDNF, whose synthesis is increased by antidepressants, and which is in part released at synaptic sites, binds to TrkB in PSDs, leading to the internalization of the BDNF-TrkB complex and, thus, to a decrease of TrkB in the PSDs. This was paralleled by greater levels of phosphorylated (ie activated) TrkB in the light membrane fraction, that contains signaling endosomes. The retrograde transport of endocyted BDNF/TrkB complexes from spines to cell bodies, where it activates the synthesis of more BDNF, is a protracted process, potentially requiring several cycles of TrkB/BDNF complex endocytosis and transport. This positive feedback mechanism may help explain the time-lag between drug administration and its therapeutic effect, that is, the antidepressant drug paradox.
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Affiliation(s)
- Ursula Wyneken
- Neuroscience Laboratory, Faculty of Medicine, Universidad de los Andes, Casilla, Santiago, Chile
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Aznavour N, Rbah L, Riad M, Reilhac A, Costes N, Descarries L, Zimmer L. A PET imaging study of 5-HT1A receptors in cat brain after acute and chronic fluoxetine treatment. Neuroimage 2006; 33:834-42. [PMID: 16996750 DOI: 10.1016/j.neuroimage.2006.08.012] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2006] [Revised: 08/04/2006] [Accepted: 08/05/2006] [Indexed: 11/28/2022] Open
Abstract
Immuno-electron microscopic and beta-microprobe studies have demonstrated that the internalization of serotonin 5-HT(1A) autoreceptors, after acute treatment with the selective 5-HT(1A) receptor agonist 8-OH-DPAT or with the specific serotonin reuptake inhibitor (SSRI) fluoxetine, is associated with a marked decrease in the in vivo binding of [(18)F]MPPF in the nucleus raphe dorsalis (NRD) of rat. To determine whether this event might be amenable to brain imaging, the present [(18)F]MPPF positron emission tomographic (PET) study was carried out in anesthetized cats given or not a single dose (5 mg/kg, i.v.) or chronically treated with fluoxetine (5 mg/kg, s.c. for 21 days). Compared to control, [(18)F]MPPF binding potential was considerably (and visibly) decreased in the cat NRD after acute fluoxetine treatment, while it remained unchanged in other brain regions. Unexpectedly, after chronic fluoxetine treatment, [(18)F]MPPF binding potential was not affected in any brain region. In parallel immuno-electron microscopic experiments carried out in rat, the density of 5-HT(1A) autoreceptors on the plasma membrane of NRD dendrites was comparable to control after chronic fluoxetine treatment. If the decrease in [(18)F]MPPF binding at the onset of SSRI treatment was detectable by PET imaging, it could potentially serve as a biological index of efficacy.
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Affiliation(s)
- Nicolas Aznavour
- Laboratoire de Neuropharmacologie, Faculté de Pharmacie, Université Lyon 1, Lyon, France
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Cannon DM, Ichise M, Fromm SJ, Nugent AC, Rollis D, Gandhi SK, Klaver JM, Charney DS, Manji HK, Drevets WC. Serotonin transporter binding in bipolar disorder assessed using [11C]DASB and positron emission tomography. Biol Psychiatry 2006; 60:207-17. [PMID: 16875929 DOI: 10.1016/j.biopsych.2006.05.005] [Citation(s) in RCA: 150] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2006] [Revised: 05/02/2006] [Accepted: 05/03/2006] [Indexed: 11/25/2022]
Abstract
BACKGROUND Evidence from neuroimaging post-mortem, and genetic studies suggests that bipolar disorder (BD) is associated with abnormalities of the serotonin-transporter (5-HTT) system. Because of various limitations of these studies, however, it has remained unclear whether 5-HTT binding is abnormal in unmedicated BD-subjects. This study used PET and [(11)C]DASB, a radioligand that afforded higher sensitivity and specificity for the 5-HTT than previously available radioligands, to compare 5-HTT binding between BD and control subjects. METHODS The 5-HTT binding-potential (BP) was assessed in 18 currently-depressed, unmedicated BD-subjects and 37 healthy controls using PET and [(11)C]DASB. RESULTS In BD, the mean 5-HTT BP was increased in thalamus, dorsal cingulate cortex (DCC), medial prefrontal cortex and insula and decreased in the brainstem at the level of the pontine raphe-nuclei. Anxiety ratings correlated positively with 5-HTT BP in insula and DCC, and BP in these regions was higher in subjects manifesting pathological obsessions and compulsions relative to BD-subjects lacking such symptoms. Subjects with a history of suicide attempts showed reduced 5-HTT binding in the midbrain and increased binding in anterior cingulate cortex versus controls and to BD-subjects without attempts. CONCLUSIONS This is the first study to report abnormalities in 5-HTT binding in unmedicated BD-subjects. The direction of abnormality in the brainstem was opposite to that found in the cortex, thalamus, and striatum. Elevated 5-HTT binding in the cortex may be related to anxiety symptoms and syndromes associated with BD.
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Affiliation(s)
- Dara M Cannon
- Mood and Anxiety Disorders Program, Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892-2670, USA.
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Takano A, Suhara T, Ichimiya T, Yasuno F, Suzuki K. Time course of in vivo 5-HTT transporter occupancy by fluvoxamine. J Clin Psychopharmacol 2006; 26:188-91. [PMID: 16633150 DOI: 10.1097/01.jcp.0000203201.34323.d3] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The pharmacokinetics of drugs with specific binding sites in the brain needs to be evaluated at these sites. In this study, we measured the time course of the selective serotonin reuptake inhibitor fluvoxamine in the human brain based on serotonin transporter (5-HTT) occupancy by positron emission tomography. Consecutive positron emission tomography scans were performed using [11C]3-amino-4-(2-dimethylaminomethyl-phenylsulfanyl)-benzonitrile before, 5 hours, 26 hours, and 53 hours after 50 mg of fluvoxamine administration in 6 healthy male volunteers (mean, 24.3 +/- 4.8 years). Quantification was performed using the multilinear reference tissue model 2. Mean 5-HTT occupancies were 72.9% +/- 4.9% at 5 hours, 50.3% +/- 11.0% at 26 hours, and 24.7% +/- 15.3% at 53 hours, and plasma concentrations were 13.9 +/- 5.5 ng/mL at 5 hours, 5.1 +/- 3.2 ng/mL at 26 hours, and 1.5 +/- 1.7 ng/mL at 53 hours. The relationship between the plasma concentration of fluvoxamine and 5-HTT occupancy at these different time points was fitted to the law of mass action.
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Affiliation(s)
- Akihiro Takano
- Brain Imaging Project, National Institute of Radiological Sciences, Chiba, Japan
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Praschak-Rieder N, Wilson AA, Hussey D, Carella A, Wei C, Ginovart N, Schwarz MJ, Zach J, Houle S, Meyer JH. Effects of tryptophan depletion on the serotonin transporter in healthy humans. Biol Psychiatry 2005; 58:825-30. [PMID: 16026765 DOI: 10.1016/j.biopsych.2005.04.038] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2005] [Revised: 04/13/2005] [Accepted: 04/19/2005] [Indexed: 11/20/2022]
Abstract
BACKGROUND Lowering of brain serotonin by acute tryptophan depletion (TD) frequently leads to transient symptoms of depression in vulnerable individuals but not in euthymic healthy subjects with a negative family history of depression. The effects of TD on regional serotonin transporter binding potential (5-HTT BP), an index of 5-HTT density and affinity, were studied in healthy individuals using 3-(11)C-amino-4-(2-dimethylaminomethylphenylsulfanyl)benzonitrile ([11C]DASB) positron emission tomography (PET). Adaptive decreases in 5-HTT density and/or affinity during TD would be a possible compensatory mechanism to maintain sufficient extracellular serotonin levels during TD, thereby preventing a depressive relapse. METHODS Regional noninvasive 5-HTT BP was found in 25 healthy subjects using [11C]DASB PET. Fourteen subjects were scanned twice, once after TD and once after sham depletion, and 11 other healthy subjects were scanned twice to measure test-retest reliability of the method. RESULTS None of the healthy subjects experienced depressive symptoms during TD and there was no difference in regional 5-HTT BP during TD as compared with sham depletion. CONCLUSIONS Acute changes in 5-HTT density or affinity are unlikely to play a role in protecting healthy subjects against mood symptoms during TD. Other mechanisms that may be associated with greater resilience against acute lowering of extracellular serotonin should be explored to gain further insight into the neurochemical basis of different vulnerabilities to short-term depressive relapse.
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Affiliation(s)
- Nicole Praschak-Rieder
- Vivian M. Rakoff PET Imaging Centre, Centre for Addiction and Mental Health, and Department of Psychiatry, University of Toronto, Toronto, Canada
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