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Saednia S, Emami S, Moslehi M, Hosseinimehr SJ. Insights into the development of 99mTc-radioligands for serotonergic receptors imaging: Synthesis, labeling, In vitro, and In vivo studies. Eur J Med Chem 2024; 270:116349. [PMID: 38555856 DOI: 10.1016/j.ejmech.2024.116349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Revised: 03/15/2024] [Accepted: 03/18/2024] [Indexed: 04/02/2024]
Abstract
Serotonergic (5-hydroxytryptamine; 5-HT) receptors play critical roles in neurological and psychological disorders such as schizophrenia, anxiety, depression, and Alzheimer's diseases. Therefore, it is particularly important to develop novel radioligands or modify the existing ones to identify the serotonergic receptors involved in psychiatric disorders. Among the 16 subtypes of serotonergic systems, only technetium-99m based radiopharmaceuticals have been evaluated for serotonin-1A (5-HT1A), serotonin-2A (5-HT2A), 5-HT1A/7 heterodimers and serotonin receptor neurotransmitter (SERT). This review focuses on recent efforts in the design, synthesis and evaluation of 99mTc-radioligands used for single photon emission computerized tomography (SPECT) imaging of serotonergic (5-HT) receptors. Additionally, the discussion will cover aspects such as chemical structure, in vitro/vivo stability, affinity toward serotonin receptors, blood-brain barrier permeation (BBB), and biodistribution study.
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Affiliation(s)
- Shahnaz Saednia
- Farabi Hospital, Isfahan University of Medical Sciences, Isfahan, Iran; Department of Radiopharmacy, Faculty of Pharmacy, Mazandaran University of Medical Sciences, Sari, Iran
| | - Saeed Emami
- Department of Medicinal Chemistry and Pharmaceutical Sciences Research Center, Faculty of Pharmacy, Mazandaran University of Medical Sciences, Sari, Iran
| | - Masoud Moslehi
- Department of Medical Physics, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Seyed Jalal Hosseinimehr
- Department of Radiopharmacy, Faculty of Pharmacy, Mazandaran University of Medical Sciences, Sari, Iran.
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Yeh SHH, Kuo YY, Huang WS, Chiu CH, Yu TH, II LGF, Tsai CJ, Cheng CY, Ma KH. Preliminary Results on the Long-Term Effects of Dextromethorphan on MDMA-Mediated Serotonergic Deficiency and Volumetric Changes in Primates Based on 4-[18F]-ADAM PET/MRI. Front Neurosci 2022; 16:837194. [PMID: 35692422 PMCID: PMC9175743 DOI: 10.3389/fnins.2022.837194] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 04/26/2022] [Indexed: 11/13/2022] Open
Abstract
Alterations to the serotonergic system due to 3,4-methylenedioxymethamphetamine (MDMA) (ecstasy) consumption have been extensively documented. However, knowledge of the reversibility of these neurotoxic effects based on in vivo evaluations of serotonin transport (SERT) availability remains limited. This study aimed to evaluate the long-term neurotoxicity of MDMA after 66 months abstinence and explored whether Dextromethorphan, a non-competitive N-methyl-D-aspartate (NMDA) receptor, could attenuate MDMA-induced neurotoxicity using 4-[18F]-ADAM, an imaging ligand that selectively targets SERT, with positron emission tomography technology (PET). Nine monkeys (Macaca cyclopis) were used in this study: control, MDMA, and DM + MDMA. Static 4-[18F]-ADAM PET was performed at 60 and 66 months after drug treatment. Serotonin transport (SERT) availability was presented as the specific uptake ratios (SURs) of 4-[18F]-ADAM in brain regions. Voxel-based region-specific SERT availability was calculated to generate 3D PET/MR images. Structural Magnetic Resonance Imaging (MRI) volumetric analysis was also conducted at 60 months. Significantly decreased 4-[18F]-ADAM SURs were observed in the striatum and thalamus of the MDMA group at 60 and 66 months compared to controls; the midbrain and frontal cortex SURs were similar at 60 and 66 months in the MDMA and control groups. All eleven brain regions showed significantly lower (∼13%) self-recovery rates over time; the occipital cortex and cingulate recovered to baseline by 66 months. DM attenuated MDMA-induced SERT deficiency on average, by ∼8 and ∼1% at 60 and 66 months, respectively; whereas significant differences were observed between the thalamus and amygdala of the MDMA and DM + MDMA groups at 66 months. Compared to controls, the MDMA group exhibited significantly increased (∼6.6%) gray matter volumes in the frontal cortex, occipital cortex, caudate nucleus, hippocampus, midbrain, and amygdala. Moreover, the gray matter volumes of the occipital cortex, hippocampus and amygdala correlated negatively with the 4-[18F]-ADAM SURs of the same regions. DM (n = 2) did not appear to affect MDMA-induced volumetric changes. The 4-[18F]-ADAM SURs, lower self-recovery rate and increased volumetric values indicate the occipital cortex, hippocampus and amygdala still exhibit MDMA-induced neurotoxicity after 66 months’ abstinence. Moreover, DM may prevent MDMA-induced serotonergic deficiency, as indicated by increased 4-[18F]-ADAM SURs and SERT availability, but not volumetric changes.
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Affiliation(s)
- Skye Hsin-Hsien Yeh
- Brain Research Center, National Yang Ming Chiao Tung University, Taipei, Taiwan
- School of Medicine, National Defense Medical Center, Taipei, Taiwan
| | - Yu-Yeh Kuo
- Department of Nursing, Hsin-Sheng College of Medical Care and Management, Taoyuan, Taiwan
| | - Wen-Sheng Huang
- Department of Nuclear Medicine, Cheng-Hsin General Hospital, Taipei, Taiwan
- Department of Nuclear Medicine, Taipei Medical University Hospital, Taipei, Taiwan
| | - Chuang-Hsin Chiu
- Department of Nuclear Medicine, Tri-Service General Hospital, Taipei, Taiwan
| | - Tsung-Hsun Yu
- Brain Research Center, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | | | - Chi-Jung Tsai
- Department of Nuclear Medicine, Taipei Medical University Hospital, Taipei, Taiwan
- *Correspondence: Kuo-Hsing Ma,
| | - Cheng-Yi Cheng
- Department of Nuclear Medicine, Tri-Service General Hospital, Taipei, Taiwan
- *Correspondence: Kuo-Hsing Ma,
| | - Kuo-Hsing Ma
- Department of Biology and Anatomy, National Defense Medical Center, Taipei, Taiwan
- *Correspondence: Kuo-Hsing Ma,
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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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Huang YY, Chang LT, Shen HY, Chen YH, Tzen KY, Shiue CY, Hsin LW. Synthesis and evaluation of 2-(2'-((dimethylamino)methyl)-4'-(2-fluoroethoxy-substituted)phenylthio)benzenamine derivatives as potential positron emission tomography imaging agents for serotonin transporters. Bioorg Chem 2020; 97:103654. [PMID: 32088418 DOI: 10.1016/j.bioorg.2020.103654] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 01/30/2020] [Accepted: 02/05/2020] [Indexed: 10/25/2022]
Abstract
A series of diphenylsulfide derivatives with various substitutions at the 4-position on phenyl ring A and different lengths of the 2-fluoroethoxy-substituted side-chain at the 4'-position on ring B were synthesized and evaluated as potential positron emission tomography (PET) imaging agents for serotonin transporters (SERT). These ligands exhibited high SERT binding affinities (Ki = 0.11-1.3 nM) and the 4-methyl-substituted (4-Me) compounds 7a and 8a displayed excellent selectivity for SERT versus norepinephrine transporters (NET) (392- and 700-fold, respectively). In the parallel artificial membrane permeability assay (PAMPA), these ligands demonstrated moderate to high brain penetration, and the 4-Me analogs showed higher BBB permeability than the corresponding 4-F analogs. The 2-fluoroethoxy-substituted ligands showed higher metabolic stability and lower lipophilicity than 4-F-ADAM. [18F]7a-c were readily prepared using an automatic synthesizer and exhibited significant uptake and slow washout in rat brains. At 120 min after iv injection, [18F]7a exhibited the highest uptake in the midbrain, whereas [18F]7b exhibited the highest uptake in the hypothalamus and midbrain. After treatment with citalopram, a SERT-selective ligand, the uptake of [18F]7a in the hypothalamus and striatum was significantly decreased. The potent and highly selective SERT binding and the selective and reversible accumulation in SERT-rich brain regions suggested that [18F]7a is a promising lead for the further development of novel [18F]-labeled PET imaging agents for SERT binding sites in the brain.
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Affiliation(s)
- Ya-Yao Huang
- PET Center, Department of Nuclear Medicine, National Taiwan University Hospital, 7, Chung-Shan S. Road, Taipei, Taiwan
| | - Li-Te Chang
- School of Pharmacy, College of Medicine, National Taiwan University, 17, Xuzhou Road, Room 936, Taipei 10055, Taiwan
| | - Hsin-Yi Shen
- School of Pharmacy, College of Medicine, National Taiwan University, 17, Xuzhou Road, Room 936, Taipei 10055, Taiwan
| | - Ying-Heng Chen
- School of Pharmacy, College of Medicine, National Taiwan University, 17, Xuzhou Road, Room 936, Taipei 10055, Taiwan
| | - Kai-Yuan Tzen
- PET Center, Department of Nuclear Medicine, National Taiwan University Hospital, 7, Chung-Shan S. Road, Taipei, Taiwan
| | - Chyng-Yann Shiue
- PET Center, Department of Nuclear Medicine, National Taiwan University Hospital, 7, Chung-Shan S. Road, Taipei, Taiwan.
| | - Ling-Wei Hsin
- School of Pharmacy, College of Medicine, National Taiwan University, 17, Xuzhou Road, Room 936, Taipei 10055, Taiwan; Center for Innovative Therapeutics Discovery, National Taiwan University, 17, Xuzhou Road, Room 936, Taipei 10055, Taiwan.
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Fully automated one-pot two-step synthesis of 4-[ 18 F]-ADAM, a potent serotonin transporter imaging agent. Appl Radiat Isot 2016; 110:8-15. [DOI: 10.1016/j.apradiso.2015.12.052] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Revised: 12/15/2015] [Accepted: 12/20/2015] [Indexed: 11/19/2022]
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Huang YY, Cheng CY, Huang WS, Ma KH, Tseng TW, Chou TK, Huang Y, Shiue CY. Toxicity and radiation dosimetry studies of the serotonin transporter radioligand [(18) F]AFM in rats and monkeys. EJNMMI Res 2015; 4:71. [PMID: 26116128 PMCID: PMC4452647 DOI: 10.1186/s13550-014-0071-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Accepted: 11/27/2014] [Indexed: 11/12/2022] Open
Abstract
Background [18 F]AFM is a potent and promising PET imaging agent for the serotonin transporter. We carried out an acute toxicity study in rats and radiation dosimetry in monkeys before the translation of the tracer to humans. Methods Single- and multiple-dose toxicity studies were conducted in Sprague–Dawley rats. Male and female rats were injected intravenously with AFM tartrate as a single dose of 98.7 or 987 μg/kg (592 or 5,920 μg/m2, 100× or 1,000× the proposed human dose of 8 μg, respectively) on day 1 or as five consecutive daily doses of 98.7 μg/kg/day (592 μg /m2/day, 100× human dose, total dose 493.5 μg/kg). PET/CT scans were performed in four Formosan rock monkeys (two males and two females, each monkey scanned twice) using a Siemens BIOGRAPH scanner. After injection of [18 F]AFM (88.5 ± 20.3 MBq), a low-dose CT scan and a series of eight whole-body PET scans in 3-D mode were performed. Time-activity data of source organs were used to calculate the residence times and estimate the absorbed radiation dose using the OLINDA/EXM software. Results In the rats, neither the single dose nor the five daily doses of AFM tartrate produced overt adverse effects clinically. In the monkeys, the radiation doses received by most organs ranged between 8.3 and 39.1 μGy/MBq. The osteogenic cells, red marrow, and lungs received the highest doses of 39.1, 35.4, and 35.1 μGy/MBq, respectively. The effective doses extrapolated to male and female adult humans were 18.0 and 18.3 μSv/MBq, respectively. Conclusions Toxicity studies in Sprague–Dawley rats and radiation dosimetry studies in Formosa rock monkeys suggest that [18 F]AFM is safe for use in human PET imaging studies. Trial registration IACUC-12-200.
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Affiliation(s)
- Ya-Yao Huang
- PET Center, Department of Nuclear Medicine, Tri-Service General Hospital, 325 Sec. 2, Cheng-Kung Road, Taipei, 114, Taiwan,
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Wu X, Cai H, Ge R, Li L, Jia Z. Recent progress of imaging agents for Parkinson's disease. Curr Neuropharmacol 2014; 12:551-63. [PMID: 25977680 PMCID: PMC4428027 DOI: 10.2174/1570159x13666141204221238] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Revised: 11/22/2014] [Accepted: 12/02/2014] [Indexed: 02/05/2023] Open
Abstract
Parkinson's disease (PD) is a common progressive, neurodegenerative brain disease that is promoted by mitochondrial dysfunction, oxidative stress, protein aggregation and proteasome dysfunction in the brain. Compared with computer tomography (CT) or magnetic resonance imaging (MRI), non-invasive nuclear radiopharmaceuticals have great significance for the early diagnosis of PD due to their high sensitivity and specificity in atypical and preclinical cases. Based on the development of coordination chemistry and chelator design, radionuclides may be delivered to lesions by attaching to PD-related transporters and receptors, such as dopamine, serotonin, and others. In this review, we comprehensively detailed the current achievements in radionuclide imaging in Parkinson's disease.
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Affiliation(s)
- Xiaoai Wu
- Department of Nuclear Medicine, West China Hospital of Sichuan University, Chengdu, P.R. China
| | - Huawei Cai
- Department of Nuclear Medicine, West China Hospital of Sichuan University, Chengdu, P.R. China
| | - Ran Ge
- Department of Nuclear Medicine, Fujian Medical University Union Hospital, Fuzhou, P.R. China
| | - Lin Li
- Department of Nuclear Medicine, West China Hospital of Sichuan University, Chengdu, P.R. China
| | - Zhiyun Jia
- Department of Nuclear Medicine, West China Hospital of Sichuan University, Chengdu, P.R. China
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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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Weng SJ, Shiue CY, Huang WS, Cheng CY, Huang SY, Li IH, Tao CC, Chou TK, Liao MH, Chang YP, Ma KH. PET imaging of serotonin transporters with 4-[18F]-ADAM in a Parkinsonian rat model. Cell Transplant 2012; 22:1295-305. [PMID: 23127756 DOI: 10.3727/096368912x658683] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
This study was undertaken to address the effects of fetal mesencephalic tissue transplantation on the serotonin system in a rat model of Parkinson's disease (PD) while also investigating the usefulness of 4-[18F]-ADAM (a serotonin transporter imaging agent) coupled with micro-PET for imaging serotonin transporters (SERTs). A PD model was induced by unilateral injection of 6-hydroxydopamine (6-OHDA) into the right medial forebrain bundle of the nigrostriatal pathway, while cell transplantation was performed via intrastriatal injection of mesencephalic brain tissue dissected from embryonic (E14) rats. The 4-[18F]-ADAM/micro-PET scanning was performed following both 6-OHDA lesioning and transplantation. Immunohistochemistry (IHC) studies were also performed following the final PET scan, and the results were compared to show a 17-43% decrease in the specific uptake ratio (SUR) and a 23-52% decrease in serotonin transporter immunoreactivity (SERT-ir) within various brain regions on the lesioned side. The number of methamphetamine-induced rotations also decreased significantly at the 4th week postgraft. In addition, striatal SUR and the SERT-ir levels were restored to 77% and 83% 5 weeks postgraft. These results suggest that Parkinson's disease also affects the serotonergic system, while both the dopaminergic and serotonergic systems can be partially restored in a rat model of PD after E14 mesencephalic tissue transplantation. In addition, we have also determined that 4-[18F]-ADAM/micro-PET can be used to detect serotonergic neuron loss, monitor the progress of Parkinson's disease, and oversee the effectiveness of therapy.
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Affiliation(s)
- Shao-Ju Weng
- Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan
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Huang WS, Huang SY, Ho PS, Ma KH, Huang YY, Yeh CB, Liu RS, Cheng CY, Shiue CY. PET imaging of the brain serotonin transporters (SERT) with N,N-dimethyl-2-(2-amino-4-[18F]fluorophenylthio)benzylamine (4-[18F]-ADAM) in humans: a preliminary study. Eur J Nucl Med Mol Imaging 2012; 40:115-24. [PMID: 23053324 DOI: 10.1007/s00259-012-2250-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Accepted: 09/03/2012] [Indexed: 10/27/2022]
Abstract
PURPOSE The aim of this study was to assess the feasibility of using 4-[(18)F]-ADAM as a brain SERT imaging agent in humans. METHODS Enrolled in the study were 19 healthy Taiwanese subjects (11 men, 8 women; age 33 ± 9 years). The PET data were semiquantitatively analyzed and expressed as specific uptake ratios (SUR) and distribution volume ratios (DVR) using the software package PMOD. The SUR and DVR of 4-[(18)F]-ADAM in the raphe nucleus (RN), midbrain (MB), thalamus (TH), striatum (STR) and prefrontal cortex (PFC) were determined using the cerebellum (CB) as the reference region. RESULTS 4-[(18)F]-ADAM bound to known SERT-rich regions in human brain. The order of the regional brain uptake was MB (RN) > TH > STR > PFC > CB. The DVR (n = 4, t* = 60 min) in the RN, TH, STR and PFC were 3.00 ± 0.50, 2.25 ± 0.45, 2.05 ± 0.31 and 1.40 ± 0.13, respectively. The optimal time for imaging brain SERT with 4-[(18)F]-ADAM was 120-140 min after injection. At the optimal imaging time, the SURs (n = 15) in the MB, TH, STR, and PFC were 2.25 ± 0.20, 2.28 ± 0.20, 2.12 ± 0.18 and 1.47 ± 0.14, respectively. There were no significant differences in SERT availability between men and women (p < 0.05). CONCLUSION The results of this study showed that 4-[(18)F]-ADAM was safe for human studies and its distribution in human brain appeared to correlate well with the known distribution of SERT in the human brain. In addition, it had high specific binding and a reasonable optimal time for imaging brain SERT in humans. Thus, 4-[(18)F]-ADAM may be feasible for assessing the status of brain SERT in humans.
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Affiliation(s)
- Wen-Sheng Huang
- Department of Nuclear Medicine, PET Center, Tri-Service General Hospital, 325 Sec. 2 Cheng-Kung Rd, Neihu, Taipei, Taiwan
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Synthesis and comparison of 4-[18F]F-ADAM, 2-[18F]F-ADAM, N-Desmethyl-4-[18F]F-ADAM and [18F]F-AFM as serotonin transporter imaging agents. Appl Radiat Isot 2012; 70:2298-307. [DOI: 10.1016/j.apradiso.2012.06.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Revised: 04/25/2012] [Accepted: 06/05/2012] [Indexed: 11/22/2022]
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Characterization of 4-[18F]-ADAM as an imaging agent for SERT in non-human primate brain using PET: a dynamic study. Nucl Med Biol 2012; 39:279-85. [DOI: 10.1016/j.nucmedbio.2011.08.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Revised: 07/21/2011] [Accepted: 08/01/2011] [Indexed: 11/21/2022]
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Huang YY, Ma KH, Tseng TW, Chou TK, Ng H, Mirsalis JC, Fu YK, Chu TC, Huang WS, Shiue CY. Biodistribution, toxicity and radiation dosimetry studies of the serotonin transporter radioligand 4-[18F]-ADAM in rats and monkeys. Eur J Nucl Med Mol Imaging 2009; 37:545-55. [PMID: 19820930 DOI: 10.1007/s00259-009-1281-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2009] [Accepted: 09/04/2009] [Indexed: 11/24/2022]
Abstract
PURPOSE 4-[(18)F]-ADAM is a potent serotonin transport imaging agent. We studied its toxicity in rats and radiation dosimetry in monkeys before human studies are undertaken. METHODS Single and multiple-dosage toxicity studies were conducted in Sprague-Dawley rats. Male and female rats were injected intravenously with 4-F-ADAM as a single dose of 1,023.7 microg/kg (1,000 times the human dose) or as five consecutive daily doses of 102.37 microg/kg (100 times the human dose). PET/CT scans were performed in seven Formosa Rock monkeys (four males and three females) using a Siemens Biograph scanner. After injection of 4-[(18)F]-ADAM (182+/-8 MBq), a low dose CT scan and a series of eight whole-body PET scans were performed. Whole-body images were acquired in 3-D mode. Time-activity data of source organs were used to calculate the residence times and estimate the absorbed radiation dose using OLINDA/EXM software. RESULTS In the rats neither the single dose nor the five daily doses of 4-F-ADAM produced overt adverse effects clinically. In the monkeys the radiation doses received by most organs ranged between 7.1 and 35.7 microGy/MBq, and the urinary bladder was considered to be the critical organ. The effective doses extrapolated to male and female adult humans were 17.4 and 21.8 microSv/MBq, respectively. CONCLUSION Toxicity studies in Sprague-Dawley rats and radiation dosimetry studies in Formosa Rock monkeys suggested that 4-[(18)F]-ADAM is safe for use in human PET imaging studies.
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Affiliation(s)
- Ya-Yao Huang
- PET Center, Department of Nuclear Medicine, Tri-Service General Hospital, 325 Sec. 2, Cheng-Kung Rd., Neihu 114, Taipei, Taiwan
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Simple and rapid preparation of [11C]DASB with high quality and reliability for routine applications. Appl Radiat Isot 2009; 67:1654-60. [DOI: 10.1016/j.apradiso.2009.03.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2008] [Revised: 02/12/2009] [Accepted: 03/10/2009] [Indexed: 01/26/2023]
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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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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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17
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Huang YY, Huang WS, Chu TC, Shiue CY. An improved synthesis of 4-[18F]-ADAM, a potent serotonin transporter imaging agent. Appl Radiat Isot 2009; 67:1063-7. [PMID: 19339192 DOI: 10.1016/j.apradiso.2009.02.090] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2008] [Revised: 02/24/2009] [Accepted: 02/25/2009] [Indexed: 10/21/2022]
Abstract
An improved synthesis of N,N-dimethyl-2-(2-amino-4-[(18)F]fluorophenylthio)benzylamine (4-[(18)F]-ADAM, 2) as a potent serotonin transporter (SERT) imaging agent is described. Molecular orbital (MO) calculation predicts that N,N-dimethyl-2-(2-nitro-4-trimethylammoniumtrifluoromethanesulfonylphenylthio)benzamide (8) is probably a better precursor than N,N-dimethyl-2-(2,4-dinitrophenylthio)benzylamine (1) for preparing 2. Radioligand 2 was synthesized by the reaction of either precursor 1 or precursor 8 with K[(18)F]/K(2.2.2) at 120 degrees C followed by reduction with BH(3) at 80 degrees C. The radiochemical yield (EOB) of 2 synthesized from precursor 1 and 8 was 5.7+/-2.4% (n=6) and 14.8+/-4.0% (n=5), respectively, in a synthesis time of 120 min from EOB. The specific activity of 2 was 3 Ci/micromol or 111 GBq/micromol (EOB). Thus, this new synthetic method has significantly improved the radiochemical yield of 4-[(18)F]-ADAM and makes this radioligand more accessible to PET Centers without a cyclotron.
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Affiliation(s)
- Ya-Yao Huang
- PET Center, Department of Nuclear Medicine, Tri-Service General Hospital 325 Section 2, Cheng-Kung Road, Neihu 114, Taipei, Taiwan
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18
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Mavel S, Vercouillie J, Garreau L, Raguza T, Ravna AW, Chalon S, Guilloteau D, Emond P. Docking study, synthesis, and in vitro evaluation of fluoro-MADAM derivatives as SERT ligands for PET imaging. Bioorg Med Chem 2008; 16:9050-5. [PMID: 18793858 DOI: 10.1016/j.bmc.2008.08.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2008] [Revised: 07/25/2008] [Accepted: 08/01/2008] [Indexed: 11/27/2022]
Abstract
In order to predict affinity of new diphenylsulfides for the serotonin transporter (SERT), a molecular modeling model was used to compare potential binding affinity of new compounds with known potent ligands. The aim of this study is to identify a suitable PET radioligand for imaging the SERT, new derivatives, and their precursors for a C-11 or F-18 radiolabeling, were synthesized. Two fluorinated derivatives displayed good in vitro affinity for the SERT (K(i)=14.3+/-1 and 10.1+/-2.7 nM) and good selectivity toward the other monoamine transporters as predicted by the docking study.
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Affiliation(s)
- Sylvie Mavel
- INSERM U930, 37000 TOURS, France; Université François-Rabelais de Tours, 37000 TOURS, France.
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19
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Peng CJ, Huang YY, Huang WS, Shiue CY. An automated synthesis of N,N-dimethyl-2-(2-amino-4-[18F]fluorophenylthio)benzylamine (4-[18F]-ADAM) for imaging serotonin transporters. Appl Radiat Isot 2008; 66:625-31. [DOI: 10.1016/j.apradiso.2007.11.009] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2007] [Revised: 10/30/2007] [Accepted: 11/13/2007] [Indexed: 11/28/2022]
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20
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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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21
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Zhu Z, Guo N, Narendran R, Erritzoe D, Ekelund J, Hwang DR, Bae SA, Laruelle M, Huang Y. The new PET imaging agent [11C]AFE is a selective serotonin transporter ligand with fast brain uptake kinetics. Nucl Med Biol 2005; 31:983-94. [PMID: 15607480 DOI: 10.1016/j.nucmedbio.2004.07.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2004] [Revised: 06/30/2004] [Accepted: 07/22/2004] [Indexed: 10/26/2022]
Abstract
A new positron emission tomography (PET) radioligand for the serotonin transporter (SERT), [(11)C]2-[2-[[(dimethylamino)methyl]phenyl]thio]-5-(2-fluoroethyl)phenylamine ([(11)C]AFE, 12), was synthesized and evaluated in vivo in rats and baboons. [(11)C]AFE (12) was prepared from its monomethylamino precursor 11 by reaction with high specific activity [(11)C]methyl triflate. Radiochemical yield was 32+/-17% based on [(11)C]methyl triflate (n=6) and specific activity was 1670+/-864 Ci/mmol at end of synthesis (EOS, n=6). Binding assays indicated that AFE displays high affinity for SERT (K(i)=1.80 nM for hSERT) and lower affinity for norepinephrine transporter (K(i)=946 nM for hNET) or dopamine transporter (K(i)>10,000 nM for hDAT). In addition, AFE displays negligible binding affinities for other serotonin and dopamine receptors, indicating an excellent binding selectivity in vitro. Biodistribution studies in rats indicated that [(11)C]AFE enters the brain readily and localizes in regions known to contain high concentrations of SERT, such as the thalamus, hypothalamus, frontal cortex and striatum. Moreover, such binding in SERT-rich brain regions is reduced significantly by pretreatment with either citalopram or the cold compound itself, but not by nisoxetine or GBR 12935, thus demonstrating that [(11)C]AFE binding in the rat brain is saturable, specific and selective for the SERT. Imaging experiments in baboons indicated that the uptake pattern of [(11)C]AFE is consistent with the known distribution of SERT in the baboon brain, with high levels of radioactivity detected in the midbrain and thalamus, moderate levels in the hippocampus and striatum and low levels in the cortical regions. The uptake kinetics of [(11)C]AFE in the baboon brain is rapid, with activity in the midbrain and thalamus peaking at 15-40 min postinjection. Pretreatment of the baboon with citalopram (4 mg/kg) 20 min before radioactivity injection reduced the binding of [(11)C]AFE in all SERT-containing brain regions to the level in the cerebellum. Kinetic analysis revealed that in all brain regions examined, [(11)C]AFE specific-to-nonspecific partition coefficients (V(3)'') are similar to those of [(11)C]McN5652 and [(11)C]2-[2-[[(dimethylamino)methyl]phenyl]thio]-5-fluorophenylamine ([(11)C]AFA), but lower than those of [(11)C]2-[2-[[(dimethylamino)methyl]phenyl]thio]-5-fluoromethylphenylamine ([(11)C]AFM) or [(11)C]DASB. In summary, [(11)C]AFE appears to be a PET radioligand with fast brain uptake kinetics and can be used for the visualization and quantification of SERT in vivo.
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Affiliation(s)
- Zhihong Zhu
- Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA
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22
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Huang Y, Bae SA, Zhu Z, Guo N, Roth BL, Laruelle M. Fluorinated diaryl sulfides as serotonin transporter ligands: synthesis, structure-activity relationship study, and in vivo evaluation of fluorine-18-labeled compounds as PET imaging agents. J Med Chem 2005; 48:2559-70. [PMID: 15801845 DOI: 10.1021/jm0400808] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A series of new, fluorine-containing substituted diphenyl sulfides was synthesized to serve as candidate ligands for positron emission tomography (PET) imaging of the serotonin transporter (SERT) and to further probe the structure-activity relationship (SAR) of this class of compounds. Candidate compounds were assayed for their affinities to the monoamine transporters (SERT, norepinephrine transporter (NET), and dopamine transporter (DAT)) in competitive binding experiments in vitro using cloned human transporters. From these in vitro assays, four compounds (7c-f) were chosen for further evaluation. All four compounds have nanomolar affinity for SERT (K(i) 1.46 nM, 1.04 nM,1.83 nM, and 3.58 nM for 7c, 7d, 7e, and 7f, respectively). The F-18-labeled compounds, 16 and 18a-c, were prepared via a two-step radiosynthesis. Biodistribution studies in rats indicated that the F-18-labeled compounds localized in brain regions with high concentrations of SERT. Furthermore, competition experiments demonstrated that the binding of these radioligands in the rat brain was saturable, specific, and selective to SERT. Specific binding in the rat hypothalamus peaked at 5.6 for ligand 16 and 4.4 for 18b at 90 min after radioactivity administration. For ligand 18a, this same ratio was 8.4 at 120 min postinjection, while compound 18c displayed a lower specific binding ratio of 2.4. In summary, four F-18-labeled ligands were prepared and evaluated as candidate PET imaging agents for SERT. Among these four ligands, three appear to be promising radioligands suitable for the labeling of SERT in vivo, with 18a providing a higher specific binding in vivo than 16 or 18b.
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Affiliation(s)
- Yiyun Huang
- Department of Psychiatry and Radiology, Columbia University College of Physicians and Surgeons, New York, New York 10032, USA
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23
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Huang Y, Narendran R, Bae SA, Erritzoe D, Guo N, Zhu Z, Hwang DR, Laruelle M. A PET imaging agent with fast kinetics: synthesis and in vivo evaluation of the serotonin transporter ligand [11C]2-[2-dimethylaminomethylphenylthio)]-5-fluorophenylamine ([11C]AFA). Nucl Med Biol 2005; 31:727-38. [PMID: 15246363 DOI: 10.1016/j.nucmedbio.2004.03.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2004] [Revised: 03/22/2004] [Accepted: 03/25/2004] [Indexed: 11/19/2022]
Abstract
A new serotonin transporter (SERT) ligand, [11C]2-[2-(dimethylaminomethylphenylthio)]-5-fluorophenylamine (10, [11C]AFA), was synthesized and evaluated as a candidate PET radioligand in pharmacological and pharmacokinetic studies. As a PET radioligand, AFA (8) can be labeled with either C-11 or F-18. In vitro, AFA displayed high affinity for SERT (Ki 1.46 +/- 0.15 nM) and lower affinity for norepinephrine transporter (NET, Ki 141.7 +/- 47.4 nM) or dopamine transporter (DAT, Ki > 10,000 nM). [11C]AFA (10) was prepared from its monomethylamino precursor 9 by reaction with high specific activity [11C]methyl iodide. Radiochemical yield was 43 +/- 20% based on [11C]methyl iodide at end of bombardment (EOB, n = 10) and specific activity was 2,129 +/- 1,369 Ci/mmol at end of synthesis (EOS, n = 10). Biodistribution studies in rats indicated that [11C]AFA accumulated in brain regions known to contain high concentrations of SERT. Binding in SERT-rich brain regions was reduced significantly by pretreatment with either the cold compound 8 or with the selective serotonin reuptake inhibitor (SSRI) citalopram, but not by the selective norepinephrine reuptake inhibitor nisoxetine, thus underlining its in vivo binding selectivity and specificity for SERT. Imaging experiments in baboons demonstrated that the uptake pattern of [11C]AFA in the baboon brain is consistent with the known distribution of SERT, with highest activity levels in the midbrain and thalamus, followed by striatum, hippocampus, and cortical regions. Activity levels in the baboon brain peaked at 15-40 min after radioligand injection, indicating a fast uptake kinetics for [11C]AFA. Pretreatment of the baboon with citalopram (4 mg/kg) significantly reduced the specific binding of [11C]AFA in all SERT-containing brain regions. Kinetic analysis revealed that the regional equilibrium specific to non-specific partition coefficients (V3") of [11C]AFA are similar to those of [11C]McN5652, but lower than those of [11C]AFM or [11C]DASB. In summary, [11C]AFA appears to be an appropriate PET radioligand with a fast brain uptake kinetics:
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Affiliation(s)
- Yiyun Huang
- Department of Psychiatry, Columbia University College of Physicians and Surgeons, 1051 Riverside Drive, Box 31, New York, NY 10032, USA.
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Scott Mason N, Mathis CA. Positron Emission Tomography Agents for Central Nervous System Drug Development Applications. ANNUAL REPORTS IN MEDICINAL CHEMISTRY 2005. [DOI: 10.1016/s0065-7743(05)40004-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
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25
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Fang P, Shiue GG, Shimazu T, Greenberg JH, Shiue CY. Synthesis and evaluation of N,N-dimethyl-2-(2-amino-5-[18F]fluorophenylthio)benzylamine (5-[18F]-ADAM) as a serotonin transporter imaging agent. Appl Radiat Isot 2004; 61:1247-54. [PMID: 15388117 DOI: 10.1016/j.apradiso.2004.03.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2003] [Revised: 02/26/2004] [Accepted: 03/03/2004] [Indexed: 11/18/2022]
Abstract
The synthesis and evaluation of a new serotonin transporter (SERT) imaging agent, N,N-dimethyl-2-(2-amino-5-[18F]fluorophenylthio)benzylamine (5-[18F]-ADAM) is reported. Nucleophilic substitution of N,N-dimethyl-2-(2-nitro-5-bromophenylthio)benzylamine with K[18F]/Kryptofix 2.2.2 in DMSO at 125 degrees C followed by reduction with NaBH4-Cu(OAc)2 in EtOH at 78 degrees C and purification with HPLC produces the desired compound with an unoptimized yield of approximately 5-10% in a synthesis time of 150 min from EOB. The biodistribution of 5-[18F]-ADAM in rats showed a high initial uptake and relatively rapid clearance in the brain (3.221+/-0.762, 0.440+/-0.059, 0.160+/-0.035 and 0.028+/-0.003% injected dose/organ at 2, 30, 60 and 120 min after I.V. injection, respectively) with the specific binding peaking at 1 h postinjection (hypothalamus/cerebellum and hippocampus/cerebellum were 2.97 and 3.59, respectively). The initial uptake in blood, lung, kidney and heart were also high, but it cleared rapidly. The radioactivity in the femur increased with time for 5-[18F]-ADAM indicating that in vivo defluorination may occur. Metabolism studies in rats showed that 5-[18F]-ADAM was not metabolized in rat brain, but was metabolized rapidly in the blood. Blocking experiments showed that there were significant decreases in the uptake of 5-[18F]-ADAM in the brain regions (hypothalamus, hippocampus and striatum) where SERT concentrations are high when rats were pretreated with (+)McN 5652 (2 mg/kg, 5 min prior to IV injection of 5-[18F]-ADAM). These results suggest that 5-[18F]-ADAM may be a potential new serotonin transporter PET imaging agent. However, due to its rapid wash-out from the brain, defluorination in vivo and lower uptake in the brain than 4-[18F]-ADAM, 5-[18F]-ADAM may not be as useful as 4-[18F]-ADAM as a SERT imaging agent.
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Affiliation(s)
- Ping Fang
- Department of Radiology, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104, USA
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26
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Shiue CY, Welch MJ. Update on PET radiopharmaceuticals: life beyond fluorodeoxyglucose. Radiol Clin North Am 2004; 42:1033-53, viii. [PMID: 15488556 DOI: 10.1016/j.rcl.2004.08.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Twenty-eight years after its inception, 2-[18F]FDG- is still the most widely used radiopharmaceutical for PET studies, but numerous more specific radiotracers have been developed and applied in neuroscience and oncology. The advances in radiotracer chemistry, especially the nucleophilic substitution reaction, have played the pivotal role in synthesizing various no-carrier-added 18F-labeled radiotracers for PET studies of various receptor systems. This article lists some of the radiotracers that are available for PET studies in neuroscience and oncology. The prospects for developing other new radiotracers for imaging other organ diseases also seem to be promising.
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Affiliation(s)
- Chyng-Yann Shiue
- Department of Radiology, University of Pennsylvania School of Medicine, 1 Silverstein, 3400 Spruce Street, Philadelphia, PA 19104, USA.
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