1
|
Andersson M, Tangen Ä, Farde L, Bölte S, Halldin C, Borg J, Lundberg J. Serotonin transporter availability in adults with autism-a positron emission tomography study. Mol Psychiatry 2021; 26:1647-1658. [PMID: 32848204 PMCID: PMC8159737 DOI: 10.1038/s41380-020-00868-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2019] [Revised: 07/30/2020] [Accepted: 08/10/2020] [Indexed: 12/11/2022]
Abstract
Impairments in social interaction and communication, in combination with restricted, repetitive behaviors and interests, define the neurodevelopmental diagnosis of autism spectrum disorder (ASD). The biological underpinnings of ASD are not well known, but the hypothesis of serotonin (5-HT) involvement in the neurodevelopment of ASD is one of the longest standing. Reuptake through the 5-HT transporter (5-HTT) is the main pathway decreasing extracellular 5-HT in the brain and a marker for the 5-HT system, but in vivo investigations of the 5-HTT and the 5-HT system in ASD are scarce and so far inconclusive. To quantify possible alterations in the 5-HT system in ASD, we used positron emission tomography and the radioligand [11C]MADAM to measure 5-HTT availability in the brain of 15 adults with ASD and 15 controls. Moreover, we examined correlations between regional 5-HTT availability and behavioral phenotype assessments regarding ASD core symptoms. In the ASD group, we found significantly lower 5-HTT availability in total gray matter, brainstem, and 9 of 18 examined subregions of gray matter. In addition, several correlations between regional 5-HTT availability and social cognitive test performance were found. The results confirm the hypothesis that 5-HTT availability is lower in the brain of adult individuals with ASD, and are consistent with the theory of 5-HT involvement in ASD neurodevelopment. The findings endorse the central role of 5-HT in the physiology of ASD, and confirm the need for a continued investigation of the 5-HT system in order to disentangle the biology of ASD.
Collapse
Affiliation(s)
- Max Andersson
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Region Stockholm, Stockholm, Sweden.
| | - Ämma Tangen
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Region Stockholm, Stockholm, Sweden
| | - Lars Farde
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Region Stockholm, Stockholm, Sweden
| | - Sven Bölte
- Department of Women's and Children's Health, Karolinska Institutet, Center of Neurodevelopmental Disorders (KIND), Center for Psychiatry Research, Stockholm Health Care Services, Region Stockholm, Stockholm, Sweden
- Child and Adolescent Psychiatry, Stockholm Health Care Services, Region Stockholm, Stockholm, Sweden
- Curtin Autism Research Group, School of Occupational Therapy, Social Work and Speech Pathology, Curtin University, Perth, WA, Australia
| | - Christer Halldin
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Region Stockholm, Stockholm, Sweden
| | - Jacqueline Borg
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Region Stockholm, Stockholm, Sweden
| | - Johan Lundberg
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Region Stockholm, Stockholm, Sweden
| |
Collapse
|
2
|
Beaurain M, Salabert AS, Ribeiro MJ, Arlicot N, Damier P, Le Jeune F, Demonet JF, Payoux P. Innovative Molecular Imaging for Clinical Research, Therapeutic Stratification, and Nosography in Neuroscience. Front Med (Lausanne) 2019; 6:268. [PMID: 31828073 PMCID: PMC6890558 DOI: 10.3389/fmed.2019.00268] [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: 02/26/2019] [Accepted: 11/01/2019] [Indexed: 01/06/2023] Open
Abstract
Over the past few decades, several radiotracers have been developed for neuroimaging applications, especially in PET. Because of their low steric hindrance, PET radionuclides can be used to label molecules that are small enough to cross the blood brain barrier, without modifying their biological properties. As the use of 11C is limited by its short physical half-life (20 min), there has been an increasing focus on developing tracers labeled with 18F for clinical use. The first such tracers allowed cerebral blood flow and glucose metabolism to be measured, and the development of molecular imaging has since enabled to focus more closely on specific targets such as receptors, neurotransmitter transporters, and other proteins. Hence, PET and SPECT biomarkers have become indispensable for innovative clinical research. Currently, the treatment options for a number of pathologies, notably neurodegenerative diseases, remain only supportive and symptomatic. Treatments that slow down or reverse disease progression are therefore the subject of numerous studies, in which molecular imaging is proving to be a powerful tool. PET and SPECT biomarkers already make it possible to diagnose several neurological diseases in vivo and at preclinical stages, yielding topographic, and quantitative data about the target. As a result, they can be used for assessing patients' eligibility for new treatments, or for treatment follow-up. The aim of the present review was to map major innovative radiotracers used in neuroscience, and explain their contribution to clinical research. We categorized them according to their target: dopaminergic, cholinergic or serotoninergic systems, β-amyloid plaques, tau protein, neuroinflammation, glutamate or GABA receptors, or α-synuclein. Most neurological disorders, and indeed mental disorders, involve the dysfunction of one or more of these targets. Combinations of molecular imaging biomarkers can afford us a better understanding of the mechanisms underlying disease development over time, and contribute to early detection/screening, diagnosis, therapy delivery/monitoring, and treatment follow-up in both research and clinical settings.
Collapse
Affiliation(s)
- Marie Beaurain
- CHU de Toulouse, Toulouse, France.,ToNIC, Toulouse NeuroImaging Center, Inserm U1214, Toulouse, France
| | - Anne-Sophie Salabert
- CHU de Toulouse, Toulouse, France.,ToNIC, Toulouse NeuroImaging Center, Inserm U1214, Toulouse, France
| | - Maria Joao Ribeiro
- UMR 1253, iBrain, Université de Tours, Inserm, Tours, France.,Inserm CIC 1415, University Hospital, Tours, France.,CHRU Tours, Tours, France
| | - Nicolas Arlicot
- UMR 1253, iBrain, Université de Tours, Inserm, Tours, France.,Inserm CIC 1415, University Hospital, Tours, France.,CHRU Tours, Tours, France
| | - Philippe Damier
- Inserm U913, Neurology Department, University Hospital, Nantes, France
| | | | - Jean-François Demonet
- Leenards Memory Centre, Department of Clinical Neuroscience, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
| | - Pierre Payoux
- CHU de Toulouse, Toulouse, France.,ToNIC, Toulouse NeuroImaging Center, Inserm U1214, Toulouse, France
| |
Collapse
|
3
|
Finnema SJ, Halldin C, Bang-Andersen B, Bundgaard C, Farde L. Serotonin transporter occupancy by escitalopram and citalopram in the non-human primate brain: a [(11)C]MADAM PET study. Psychopharmacology (Berl) 2015; 232:4159-67. [PMID: 25980484 DOI: 10.1007/s00213-015-3961-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 05/05/2015] [Indexed: 11/29/2022]
Abstract
RATIONALE A number of serotonin receptor positron emission tomography (PET) radioligands have been shown to be sensitive to changes in extracellular serotonin concentration, in a generalization of the well-known dopamine competition model. High doses of selective serotonin reuptake inhibitors (SSRIs) decrease serotonin receptor availability in monkey brain, consistent with increased serotonin concentrations. However, two recent studies on healthy human subjects, using a single, lower and clinically relevant SSRI dose, showed increased cortical serotonin receptor radioligand binding, suggesting potential decreases in serotonin concentration in projection regions when initiating treatment. OBJECTIVES The cross-species differential SSRI effect may be partly explained by serotonin transporter (SERT) occupancy in monkey brain being higher than is clinically relevant. We here determine SERT occupancy after single doses of escitalopram or citalopram by conducting PET measurements with [(11)C]MADAM in monkeys. Relationships between dose, plasma concentration and SERT occupancy were estimated by one-site binding analyses. Binding affinity was expressed as dose (ID50) or plasma concentration (K i) where 50 % SERT occupancy was achieved. RESULTS Estimated ID50 and K i values were 0.020 mg/kg and 9.6 nmol/L for escitalopram and 0.059 mg/kg and 9.7 nmol/L for citalopram, respectively. Obtained K i values are comparable to values reported in humans. CONCLUSIONS Escitalopram or citalopram doses nearly saturated SERT in previous monkey studies which examined serotonin sensitivity of receptor radioligands. PET-measured cross-species differential effects of SSRI on cortical serotonin concentration may thus be related to SSRI dose. Future monkey studies using SSRI doses inducing clinically relevant SERT occupancy may further illuminate the delayed onset of SSRI therapeutic effects.
Collapse
Affiliation(s)
- Sjoerd J Finnema
- Department of Clinical Neuroscience, Center for Psychiatric Research, Karolinska Institutet, Karolinska University Hospital, Building R5:02, SE-17176, Stockholm, Sweden. .,Department of Diagnostic Radiology, Yale University, New Haven, CT, USA.
| | - Christer Halldin
- Department of Clinical Neuroscience, Center for Psychiatric Research, Karolinska Institutet, Karolinska University Hospital, Building R5:02, SE-17176, Stockholm, Sweden
| | | | | | - Lars Farde
- Department of Clinical Neuroscience, Center for Psychiatric Research, Karolinska Institutet, Karolinska University Hospital, Building R5:02, SE-17176, Stockholm, Sweden.,AstraZeneca, Translational Science Center at Karolinska Institutet, Stockholm, Sweden
| |
Collapse
|
4
|
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.
Collapse
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
| |
Collapse
|
5
|
Batis J, Barret O, Alagille D, Koren AO, Stehouwer JS, Cosgrove K, Goodman M, Seibyl J, Tamagnan G. In vivo evaluation of [¹²³I]mZIENT as a SPECT radioligand for the serotonin transporter. Nucl Med Biol 2013; 39:1137-41. [PMID: 23084043 DOI: 10.1016/j.nucmedbio.2012.07.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2011] [Revised: 06/18/2012] [Accepted: 07/23/2012] [Indexed: 10/27/2022]
Abstract
INTRODUCTION In vivo imaging of the serotonin transporter continues to be a valuable tool in drug development and in monitoring diseases that alter serotonergic function. The purposes of this study were to: 1) evaluate the test/retest reproducibility of [¹²³I] 2β-Carbomethoxy-3β-(3'-((Z)-2-iodoethenyl)phenyl)nortropane ([¹²³I]mZIENT); and 2) to assess displacement of [¹²³I]mZIENT following administration of SERT specific drugs. METHODS Six female baboons (Papio anubis) were scanned following i.v. administration of [¹²³I]mZIENT. The regional binding potential (BP(nd)) was determined using a simplified reference tissue model, with the cerebellum used as a reference region. The test/retest reproducibility of BP(nd) was determined following repeated injection of [¹²³I]mZIENT on a different day. To assess the displacement of [¹²³I]mZIENT from SERT, citalopram (0.01-5mg/kg) or sertraline (0.01-0.5mg/kg) was given as iv bolus at ~4h following administration of [¹²³I]mZIENT. RESULTS The test/retest variability of BP(nd) was less than 10% for all SERT-rich brain regions. Estimates of ED50 for displacement of [¹²³I]mZIENT in SERT-rich regions were consistent with previous reports for the [¹¹C] analog of [¹²³I]mZIENT. Both citalopram and sertraline displaced [¹²³I]mZIENT from SERT in a dose-dependent manner, with maximal observed displacements of greater than 80% in the diencephalon and greater than 75% in brainstem for both citalopram and sertraline. CONCLUSIONS [¹²³I] mZIENT demonstrates good test-retest reproducibility; and initial displacement studies suggest that this compound is highly selective for SERT. Overall, this radioligand has favorable characteristics for use in drug development studies and/or longitudinal studies interrogating SERT.
Collapse
Affiliation(s)
- Jeffery Batis
- Institute for Neurodegenerative Disorders, New Haven, CT 06510, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
6
|
Klomp A, den Hollander B, de Bruin K, Booij J, Reneman L. The effects of ecstasy (MDMA) on brain serotonin transporters are dependent on age-of-first exposure in recreational users and animals. PLoS One 2012; 7:e47524. [PMID: 23115651 PMCID: PMC3480359 DOI: 10.1371/journal.pone.0047524] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2012] [Accepted: 09/10/2012] [Indexed: 11/30/2022] Open
Abstract
Rationale and Objective Little is known on the effects of ecstasy (MDMA, a potent 5-HT-releaser and neurotoxin) exposure on brain development in teenagers. The objective of this study was to investigate whether in humans, like previous observations made in animals, the effects of MDMA on the 5-HT system are dependent on age-of-first exposure. Methods 5-HT transporter (SERT) densities in the frontal cortex and midbrain were assessed with [123I]β-CIT single photon emission computed tomography in 33 users of ecstasy. Subjects were stratified for early-exposed users (age-at-first exposure 14–18 years; developing brain), and late-exposed users (age-at-first exposure 18–36 years; mature brain). In parallel, we investigated the effects of age experimentally with MDMA in early-exposed (adolescent) rats and late-exposed (adult) rats using the same radioligand. Results On average, five years after first exposure, we found a strong inverse relationship, wherein age-at-first exposure predicted 79% of the midbrain SERT variability in early (developing brain) exposed ecstasy users, whereas this was only 0.3% in late (mature brain) exposed users (p = 0.007). No such effect was observed in the frontal cortex. In rats, a significant age-BY-treatment effect (p<0.01) was observed as well, however only in the frontal cortex. Conclusions These age-related effects most likely reflect differences in the maturational stage of the 5-HT projection fields at age-at-first exposure and enhanced outgrowth of the 5-HT system due to 5-HT’s neurotrophic effects. Ultimately, our findings stress the need for more knowledge on the effects of pharmacotherapies that alter brain 5-HT levels in the pediatric population.
Collapse
Affiliation(s)
- Anne Klomp
- Brain Imaging Center, Academic Medical Center, Amsterdam, The Netherlands
- Department of Radiology, Academic Medical Center, Amsterdam, The Netherlands
| | | | - Kora de Bruin
- Department of Nuclear Medicine, Academic Medical Center, Amsterdam, The Netherlands
| | - Jan Booij
- Brain Imaging Center, Academic Medical Center, Amsterdam, The Netherlands
- Department of Nuclear Medicine, Academic Medical Center, Amsterdam, The Netherlands
| | - Liesbeth Reneman
- Brain Imaging Center, Academic Medical Center, Amsterdam, The Netherlands
- Department of Radiology, Academic Medical Center, Amsterdam, The Netherlands
- * E-mail:
| |
Collapse
|
7
|
Ratner C, Ettrup A, Bueter M, Haahr ME, Compan V, le Roux CW, Levin B, Hansen HH, Knudsen GM. Cerebral markers of the serotonergic system in rat models of obesity and after Roux-en-Y gastric bypass. Obesity (Silver Spring) 2012; 20:2133-41. [PMID: 22450706 PMCID: PMC3562999 DOI: 10.1038/oby.2012.75] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Food intake and body weight are regulated by a complex system of neural and hormonal signals, of which the anorexigenic neurotransmitter serotonin (5-hydroxytryptamine or 5-HT) is central. In this study, rat models of obesity and weight loss intervention were compared with regard to several 5-HT markers. Using receptor autoradiography, brain regional-densities of the serotonin transporter (SERT) and the 5-HT(2A) and 5-HT(4) receptors were measured in (i) selectively bred polygenic diet-induced obese (pgDIO) rats, (ii) outbred DIO rats, and (iii) Roux-en-Y gastric bypass (RYGB)-operated rats. pgDIO rats had higher 5-HT(4) and 5-HT(2A) receptor binding and lower SERT binding when compared to polygenic diet-resistant (pgDR) rats. The most pronounced difference between pgDIO and pgDR rats was observed in the nucleus accumbens shell (NAcS), a brain region regulating reward aspects of feeding. No differences were found in the 5-HT markers between DIO rats, chow-fed control rats, and DIO rats experiencing a weight loss. The 5-HT markers were also similar in RYGB and sham-operated rats except for a downregulation of 5-HT(2A) receptors in the NAcS. The higher receptor and lower SERT binding in pgDIO as compared to pgDR rats corresponds to what is reported in overweight humans and suggests that the dysfunctions of the 5-HT system associated with overeating or propensity to become overweight are polygenically determined. Our results support that the obesity-prone rat model has high translational value and suggests that susceptibility to develop obesity is associated with changed 5-HT tone in the brain that may also regulate hedonic aspects of feeding.
Collapse
Affiliation(s)
- Cecilia Ratner
- Neurobiology Research Unit and Center for Integrated Molecular Brain Imaging, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Anders Ettrup
- Neurobiology Research Unit and Center for Integrated Molecular Brain Imaging, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Marco Bueter
- Department of Surgery, Division of Visceral and Transplantation Surgery, University Hospital, Zürich, Switzerland
| | - Mette E. Haahr
- Neurobiology Research Unit and Center for Integrated Molecular Brain Imaging, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Valérie Compan
- CNRS, UMR-5203, Institut de Génomique Fonctionnelle, Montpellier, France; 2, INSERM, U661, Montpellier, France; 3, Universités de Montpellier 1 & 2, UMR-5203, Montpellier, France; Université de Nîmes, Nîmes, France
| | | | - Barry Levin
- Neurology Service, VA Medical Center, East Orange, New Jersey, USA
- Department of Neurology and Neurosciences, New Jersey Medical School/UMDNJ, Newark, New Jersey, USA
| | | | - Gitte M. Knudsen
- Neurobiology Research Unit and Center for Integrated Molecular Brain Imaging, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| |
Collapse
|
8
|
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]
|
9
|
Areberg J, Luntang-Jensen M, Søgaard B, Nilausen DØ. Occupancy of the Serotonin Transporter after Administration of Lu AA21004 and its Relation to Plasma Concentration in Healthy Subjects. Basic Clin Pharmacol Toxicol 2011; 110:401-4. [DOI: 10.1111/j.1742-7843.2011.00810.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
10
|
Yubero-Lahoz S, Ayestas MA, Blough BE, Partilla JS, Rothman RB, de la Torre R, Baumann MH. Effects of MDMA and related analogs on plasma 5-HT: relevance to 5-HT transporters in blood and brain. Eur J Pharmacol 2011; 674:337-44. [PMID: 22079770 DOI: 10.1016/j.ejphar.2011.10.033] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Revised: 10/13/2011] [Accepted: 10/27/2011] [Indexed: 11/25/2022]
Abstract
(±)-3,4-Methylenedioxymethamphetamine (MDMA) is an illicit drug that evokes transporter-mediated release of serotonin (5-HT) in the brain. 5-HT transporter (SERT) proteins are also expressed in non-neural tissues (e.g., blood), and evidence suggests that MDMA targets platelet SERT to increase plasma 5-HT. Here we tested two hypotheses related to the effects of MDMA on circulating 5-HT. First, to determine if MDMA metabolites might contribute to actions of the drug in vivo, we used in vitro microdialysis in rat blood specimens to examine the effects of MDMA and its metabolites on plasma 5-HT. Second, to determine whether effects of MDMA on plasma 5-HT might be used as an index of central SERT activity, we carried out in vivo microdialysis in blood and brain after intravenous MDMA administration. The in vitro results show that test drugs evoke dose-related increases in plasma 5-HT ranging from two- to sevenfold above baseline, with MDMA and its metabolite, (±)-3,4-methylenedioxyamphetamine (MDA), producing the largest effects. The ability of MDMA and related analogs to elevate plasma 5-HT is correlated with their potency as SERT substrates in rat brain synaptosomes. The in vivo results reveal that MDMA causes concurrent increases in extracellular 5-HT in blood and brain, but there are substantial individual differences in responsiveness to the drug. Collectively, our findings indicate that MDMA and its metabolites increase plasma 5-HT by a SERT-dependent mechanism, and suggest the possibility that measures of evoked 5-HT release in blood may reflect central SERT activity.
Collapse
Affiliation(s)
- Samanta Yubero-Lahoz
- Human Pharmacology and Clinical Neurosciences Research Group, Neurosciences Research Program, IMIM-Hospital del Mar Research Institute, Barcelona, Spain
| | | | | | | | | | | | | |
Collapse
|
11
|
Development and validation of a rapid LC-ESI-MS/MS method for quantification of fluoxetine and its application to MS binding assays. Anal Bioanal Chem 2011; 400:3505-15. [PMID: 21516443 DOI: 10.1007/s00216-011-4997-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2011] [Revised: 04/01/2011] [Accepted: 04/07/2011] [Indexed: 10/18/2022]
Abstract
In the present study, a rapid and sensitive LC-ESI-MS/MS method for quantification of (S)-fluoxetine as a native marker in mass spectrometry (MS) binding assays addressing the human serotonin transporter (hSERT) was developed and validated. The concept of MS binding assays based on mass spectrometric quantification of a nonlabeled marker recently introduced by us represents a promising alternative to conventional radioligand binding without the drawbacks inherently connected with radioisotope labeling. For high-performance liquid chromatography (HPLC), a 20 × 2-mm RP-18 column with a mobile phase composed of acetonitrile and ammonium bicarbonate buffer (5 mmol L(-1), pH 9.5) at a ratio of 80:20 (v/v) and a flow rate of 800 μL min(-1) in an isocratic mode were used, resulting in a chromatographic cycle time of 60 s. Employing [(2)H(5)]fluoxetine as internal standard enabled ESI-MS/MS quantification of (S)-fluoxetine between 3 nmol L(-1) and 50 pmol L(-1) (LLOQ) in matrix obtained from binding experiments without the need of any sample preparation. Validation of the method showed that linearity, intra-, and inter-batch accuracy as well as precision meet the requirements of the FDA guidance for bioanalytical method validation. Considering sensitivity and speed, the established method is clearly superior to those published for biological matrices so far. Furthermore, the method was transferred to other RP-18 columns of different lengths and respective validation experiments demonstrated its versatility and chromatographic robustness. Finally, the newly developed method was successfully applied to MS binding assays for hSERT. The affinity determined for (S)-fluoxetine in saturation experiments was in good agreement with literature data obtained in respective radioligand binding assays.
Collapse
|
12
|
Differential effects of cocaine and MDMA self-administration on cortical serotonin transporter availability in monkeys. Neuropharmacology 2011; 61:245-51. [PMID: 21521647 DOI: 10.1016/j.neuropharm.2011.04.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Revised: 04/04/2011] [Accepted: 04/07/2011] [Indexed: 01/23/2023]
Abstract
Cocaine self-administration alters brain dopaminergic and serotonergic function primarily in mesolimbic and prefrontal brain regions whereas 3,4-methylenedioxymethamphetamine (MDMA) self-administration predominately alters brain serotonergic function in a more widespread distribution across cortical regions. We previously reported that, compared to drug-naïve rhesus monkeys, self-administration of cocaine but not MDMA was associated with increased serotonin transporter (SERT) availability in two mesolimbic regions, the caudate nucleus and putamen, as measured by positron emission tomography (PET) using the SERT-specific ligand [(11)C]-3-amino-4(2-dimethylamino-methyl-phenylsulfanyl)-benzonitrile ([(11)C]DASB). The goal of the present study was to extend this comparison between cocaine and MDMA self-administration to SERT availability in cortical regions, which have been shown previously to be affected in human drug abusers and are associated with executive function. PET studies using [(11)C]DASB were conducted in adult male rhesus monkeys with a history of cocaine (mean intake = 742.6 mg/kg) or MDMA (mean intake = 121.0 mg/kg) self-administration, and drug-naïve controls (n = 4/group). Regions of interest were drawn for several cortical (prefrontal, temporal, parietal, occipital and midcingulate) and subcortical (thalamus, amygdala and hippocampus) areas. Cortical SERT availability was significantly higher in monkeys with a cocaine self-administration history compared to controls whereas MDMA self-administration resulted in lower levels of SERT availability. These data extend our previous findings indicating that cocaine and MDMA self-administration differentially alter SERT availability in subcortical and cortical regions, which may have implications for development of treatment drugs.
Collapse
|
13
|
Madsen J, Elfving B, Frokjaer VG, Kornum BR, Thomsen G, Martiny L, Knudsen GM. Synthesis and biological evaluation of 125I/123I-labelled analogues of citalopram and escitalopram as potential radioligands for imaging of the serotonin transporter. J Labelled Comp Radiopharm 2010. [DOI: 10.1002/jlcr.1841] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
14
|
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.
Collapse
|
15
|
Kovačević T, Skelin I, Diksic M. Chronic fluoxetine treatment has a larger effect on the density of a serotonin transporter in the Flinders Sensitive Line (FSL) rat model of depression than in normal rats. Synapse 2009; 64:231-40. [DOI: 10.1002/syn.20721] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
16
|
Stehouwer JS, Jarkas N, Zeng F, Voll RJ, Williams L, Camp VM, Malveaux EJ, Votaw JR, Howell L, J.Owens M, Goodman MM. Synthesis, radiosynthesis, and biological evaluation of fluorine-18-labeled 2beta-carbo(fluoroalkoxy)-3beta-(3'-((Z)-2-haloethenyl)phenyl)nortropanes: candidate radioligands for in vivo imaging of the serotonin transporter with positron emission tomography. J Med Chem 2008; 51:7788-99. [PMID: 19053782 PMCID: PMC2668213 DOI: 10.1021/jm800781a] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The meta-vinylhalide fluoroalkyl ester nortropanes 1-4 were synthesized as ligands of the serotonin transporter (SERT) for use as positron emission tomography (PET) imaging agents. In vitro competition binding assays demonstrated that 1-4 have a high affinity for the SERT (K(i) values = 0.3-0.4 nM) and are selective for the SERT over the dopamine and norepinephrine transporters (DAT and NET). MicroPET imaging in anesthetized cynomolgus monkeys with [(18)F]1-[(18)F]4 demonstrated that all four tracers behave similarly with peak uptake in the SERT-rich brain regions achieved after 45-55 min, followed by a steady washout. An awake monkey study was performed with [(18)F]1, which demonstrated that the uptake of [(18)F]1 was not influenced by anesthesia. Chase studies with the SERT ligand 15 displaced [(18)F]1-[(18)F]4, but chase studies with the DAT ligand 16 did not displace [(18)F]1-[(18)F]4 thus indicating that the tracers were binding specifically to the SERT.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | | | | | | | - Mark M. Goodman
- To whom correspondence should be addressed. Department of Radiology, Emory University, 1364 Clifton Road NE, Atlanta, GA 30322 Phone: (404) 727-9366. Fax: (404) 727-3488. E-mail:
| |
Collapse
|
17
|
Rosso L, Gee AD, Gould IR. Ab initiocomputational study of positron emission tomography ligands interacting with lipid molecule for the prediction of nonspecific binding. J Comput Chem 2008; 29:2397-405. [DOI: 10.1002/jcc.20972] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
18
|
Bois F, Baldwin RM, Amici L, Al-Tikriti MS, Kula N, Baldessarini R, Innis RB, Staley JK, Tamagnan. GD. Synthesis, radiolabeling and baboon SPECT imaging of 2beta-carbomethoxy-3beta-(3'-[(123)I]iodophenyl)tropane ([(123)I]YP256) as a serotonin transporter radiotracer. Nucl Med Biol 2008; 35:53-9. [PMID: 18158943 PMCID: PMC2276982 DOI: 10.1016/j.nucmedbio.2007.09.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2006] [Revised: 09/05/2007] [Accepted: 09/07/2007] [Indexed: 11/18/2022]
Abstract
To develop a potential SPECT probe to evaluate the integrity of the serotoninergic system (5-HTT) whose dysfunction is linked to several disease conditions such as Parkinson's disease, Alzheimer's disease and depression, we report the synthesis, radiolabeling and in vivo baboon imaging of 2beta-carbomethoxy-3beta-(3'-[(123)I]iodophenyl) tropane (YP256, 6). The radiolabeling was performed by iododestannylation using sodium [(123)I]iodide and peracetic acid. Although the ligand displayed high selectivity for 5-HTT over dopamine transporter in vitro, SPECT imaging in baboons did not reveal selective 5-HTT accumulation in brain in vivo.
Collapse
Affiliation(s)
- Frederic Bois
- Yale University, School of Medicine, VA Connecticut HCS (116A2), 950 Campbell Avenue, West Haven CT 06516, USA. Department of Psychiatry & Neuroscience Program, Harvard Medical School, Mailman Research Center McLean Division of Massachusetts General Hospital, Belmont, MA 02478, USA, Institute for Neurodegenerative Disorders, 60 Temple Street, New Haven 06510, CT, USA
| | - Ronald M. Baldwin
- Yale University, School of Medicine, VA Connecticut HCS (116A2), 950 Campbell Avenue, West Haven CT 06516, USA. Department of Psychiatry & Neuroscience Program, Harvard Medical School, Mailman Research Center McLean Division of Massachusetts General Hospital, Belmont, MA 02478, USA, Institute for Neurodegenerative Disorders, 60 Temple Street, New Haven 06510, CT, USA
| | - Louis Amici
- Yale University, School of Medicine, VA Connecticut HCS (116A2), 950 Campbell Avenue, West Haven CT 06516, USA. Department of Psychiatry & Neuroscience Program, Harvard Medical School, Mailman Research Center McLean Division of Massachusetts General Hospital, Belmont, MA 02478, USA, Institute for Neurodegenerative Disorders, 60 Temple Street, New Haven 06510, CT, USA
| | - Mohammed S. Al-Tikriti
- Yale University, School of Medicine, VA Connecticut HCS (116A2), 950 Campbell Avenue, West Haven CT 06516, USA. Department of Psychiatry & Neuroscience Program, Harvard Medical School, Mailman Research Center McLean Division of Massachusetts General Hospital, Belmont, MA 02478, USA, Institute for Neurodegenerative Disorders, 60 Temple Street, New Haven 06510, CT, USA
| | - Nora Kula
- Yale University, School of Medicine, VA Connecticut HCS (116A2), 950 Campbell Avenue, West Haven CT 06516, USA. Department of Psychiatry & Neuroscience Program, Harvard Medical School, Mailman Research Center McLean Division of Massachusetts General Hospital, Belmont, MA 02478, USA, Institute for Neurodegenerative Disorders, 60 Temple Street, New Haven 06510, CT, USA
| | - Ross Baldessarini
- Yale University, School of Medicine, VA Connecticut HCS (116A2), 950 Campbell Avenue, West Haven CT 06516, USA. Department of Psychiatry & Neuroscience Program, Harvard Medical School, Mailman Research Center McLean Division of Massachusetts General Hospital, Belmont, MA 02478, USA, Institute for Neurodegenerative Disorders, 60 Temple Street, New Haven 06510, CT, USA
| | - Robert B. Innis
- Yale University, School of Medicine, VA Connecticut HCS (116A2), 950 Campbell Avenue, West Haven CT 06516, USA. Department of Psychiatry & Neuroscience Program, Harvard Medical School, Mailman Research Center McLean Division of Massachusetts General Hospital, Belmont, MA 02478, USA, Institute for Neurodegenerative Disorders, 60 Temple Street, New Haven 06510, CT, USA
| | - Julie K. Staley
- Yale University, School of Medicine, VA Connecticut HCS (116A2), 950 Campbell Avenue, West Haven CT 06516, USA. Department of Psychiatry & Neuroscience Program, Harvard Medical School, Mailman Research Center McLean Division of Massachusetts General Hospital, Belmont, MA 02478, USA, Institute for Neurodegenerative Disorders, 60 Temple Street, New Haven 06510, CT, USA
| | - Gilles D. Tamagnan.
- Yale University, School of Medicine, VA Connecticut HCS (116A2), 950 Campbell Avenue, West Haven CT 06516, USA. Department of Psychiatry & Neuroscience Program, Harvard Medical School, Mailman Research Center McLean Division of Massachusetts General Hospital, Belmont, MA 02478, USA, Institute for Neurodegenerative Disorders, 60 Temple Street, New Haven 06510, CT, USA
| |
Collapse
|