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Li X, Feng D, Ma S, Li M, Zhao S, Tang M. Ventral hippocampus is more sensitive to fluoxetine-induced changes in extracellular 5-HT concentration, membrane 5-HT transporter level and immobility times. Neuropharmacology 2024; 242:109766. [PMID: 37858884 DOI: 10.1016/j.neuropharm.2023.109766] [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: 07/06/2023] [Revised: 09/26/2023] [Accepted: 10/15/2023] [Indexed: 10/21/2023]
Abstract
Hippocampal responses to selective 5-HT reuptake inhibitor (SSRI) have long been studied. However, its sub-regional involvements in mediating SSRI's pharmacological effects have not been fully addressed. The current study sought to investigate neurochemical, neurobiological and neurobehavioral changes in response to direct fluoxetine perfusion into the ventral and dorsal sub-regions of the hippocampus in C57BL/6 mice. Following fluoxetine perfusion, time courses of dialysate 5-HT, 5-HT transporter (5-HTT) protein (total, membrane and cytoplasmic fractions), locomotion, and immobility times in the forced swim test (FST) and tail suspension test (TST) were determined. At baseline, 5-HT uptake efficiency assessed by the no-net-flux microdialysis, and 5-HTT protein were measured as well. Results show that fluoxetine dose-dependently increased dialysate 5-HT, lowered membrane 5-HTT protein and increased cytoplasmic fraction without changing the total level, decreased immobility times in both the FST and TST, with greater responses all detected in the ventral sub-region compared to the dorsal sub-region. Fluoxetine didn't affect locomotor activity, ruling out the possibility that fluoxetine's effects on immobility maybe due to alteration in locomotion. Besides, lower 5-HT uptake efficiency and lower membrane 5-HTT protein level were found in the ventral sub-region at baseline. Together, the sub-regional differences at baseline and in responses to fluoxetine added powerful evidence to support the existence of two distinct 5-HT sub-systems in the hippocampus, with greater changes to fluoxetine detected in the ventral sub-system.
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Affiliation(s)
- Xiang Li
- Department of Pharmacy, The Fourth Affiliated Hospital of China Medical University, Shenyang, 110032, China
| | - Dan Feng
- Department of Clinical Pharmacology, College of Pharmacy, China Medical University, Shenyang, 110122, China
| | - Shenglu Ma
- Department of Clinical Pharmacology, College of Pharmacy, China Medical University, Shenyang, 110122, China
| | - Mingxing Li
- Department of Clinical Pharmacology, College of Pharmacy, China Medical University, Shenyang, 110122, China
| | - Shulei Zhao
- Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, MD, 20993, USA
| | - Man Tang
- Department of Clinical Pharmacology, College of Pharmacy, China Medical University, Shenyang, 110122, China.
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2
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Ľupták M, Fišar Z, Hroudová J. Different Effects of SSRIs, Bupropion, and Trazodone on Mitochondrial Functions and Monoamine Oxidase Isoform Activity. Antioxidants (Basel) 2023; 12:1208. [PMID: 37371937 DOI: 10.3390/antiox12061208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 05/23/2023] [Accepted: 05/31/2023] [Indexed: 06/29/2023] Open
Abstract
Mitochondrial dysfunction is involved in the pathophysiology of psychiatric and neurodegenerative disorders and can be used as a modulator and/or predictor of treatment responsiveness. Understanding the mitochondrial effects of antidepressants is important to connect mitochondria with their therapeutic and/or adverse effects. Pig brain-isolated mitochondria were used to evaluate antidepressant-induced changes in the activity of electron transport chain (ETC) complexes, monoamine oxidase (MAO), mitochondrial respiratory rate, and ATP. Bupropion, escitalopram, fluvoxamine, sertraline, paroxetine, and trazodone were tested. All tested antidepressants showed significant inhibition of complex I and IV activities at high concentrations (50 and 100 µmol/L); complex II + III activity was reduced by all antidepressants except bupropion. Complex I-linked respiration was reduced by escitalopram >> trazodone >> sertraline. Complex II-linked respiration was reduced only by bupropion. Significant positive correlations were confirmed between complex I-linked respiration and the activities of individual ETC complexes. MAO activity was inhibited by all tested antidepressants, with SSRIs causing a greater effect than trazodone and bupropion. The results indicate a probable association between the adverse effects of high doses of antidepressants and drug-induced changes in the activity of ETC complexes and the respiratory rate of mitochondria. In contrast, MAO inhibition could be linked to the antidepressant, procognitive, and neuroprotective effects of the tested antidepressants.
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Affiliation(s)
- Matej Ľupták
- Institute of Pharmacology, First Faculty of Medicine, Charles University and General University Hospital in Prague, Albertov 4, 128 00 Prague, Czech Republic
| | - Zdeněk Fišar
- Department of Psychiatry, First Faculty of Medicine, Charles University and General University Hospital in Prague, Ke Karlovu 11, 120 00 Prague, Czech Republic
| | - Jana Hroudová
- Institute of Pharmacology, First Faculty of Medicine, Charles University and General University Hospital in Prague, Albertov 4, 128 00 Prague, Czech Republic
- Department of Psychiatry, First Faculty of Medicine, Charles University and General University Hospital in Prague, Ke Karlovu 11, 120 00 Prague, Czech Republic
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3
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Kim HK, Song J. Hypothyroidism and Diabetes-Related Dementia: Focused on Neuronal Dysfunction, Insulin Resistance, and Dyslipidemia. Int J Mol Sci 2022; 23:ijms23062982. [PMID: 35328405 PMCID: PMC8952212 DOI: 10.3390/ijms23062982] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 03/06/2022] [Accepted: 03/07/2022] [Indexed: 01/27/2023] Open
Abstract
The incidence of dementia is steadily increasing worldwide. The risk factors for dementia are diverse, and include genetic background, environmental factors, sex differences, and vascular abnormalities. Among the subtypes of dementia, diabetes-related dementia is emerging as a complex type of dementia related to metabolic imbalance, due to the increase in the number of patients with metabolic syndrome and dementia worldwide. Thyroid hormones are considered metabolic regulatory hormones and affect various diseases, such as liver failure, obesity, and dementia. Thyroid dysregulation affects various cellular mechanisms and is linked to multiple disease pathologies. In particular, hypothyroidism is considered a critical cause for various neurological problems-such as metabolic disease, depressive symptoms, and dementia-in the central nervous system. Recent studies have demonstrated the relationship between hypothyroidism and brain insulin resistance and dyslipidemia, leading to diabetes-related dementia. Therefore, we reviewed the relationship between hypothyroidism and diabetes-related dementia, with a focus on major features of diabetes-related dementia such as insulin resistance, neuronal dysfunction, and dyslipidemia.
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Affiliation(s)
- Hee Kyung Kim
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Chonnam National University Medical School, 264 Seoyangro, Hwasun 58128, Korea;
| | - Juhyun Song
- Department of Anatomy, Chonnam National University Medical School, Hwasun 58128, Korea
- BioMedical Sciences Graduate Program (BMSGP), Chonnam National University, 264 Seoyangro, Hwasun 58128, Korea
- Correspondence: ; Tel.: +82-61-379-2706; Fax: +82-61-375-5834
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4
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Silva S, Bicker J, Fonseca C, Ferreira NR, Vitorino C, Alves G, Falcão A, Fortuna A. Encapsulated Escitalopram and Paroxetine Intranasal Co-Administration: In Vitro/In Vivo Evaluation. Front Pharmacol 2021; 12:751321. [PMID: 34925013 PMCID: PMC8675330 DOI: 10.3389/fphar.2021.751321] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Accepted: 11/05/2021] [Indexed: 01/16/2023] Open
Abstract
Depression is a common mental disorder. Its treatment with selective serotonin reuptake inhibitors (SSRIs) is effective only in a fraction of patients, and pharmacoresistance is increasing steadily. Intranasal (IN) drug delivery to the brain stands out as a promising strategy to improve current therapeutic approaches by operating as a shuttle to overcome the blood–brain barrier. This work aimed to simultaneously administer escitalopram and paroxetine by IN route to mice. For this purpose, three nanostructured lipid carriers (NLC1, NLC2, and BorNLC) and one nanoemulsion (NE) were tested for drug loading. After their characterization, investigation of their impact on nasal cell viability and SSRI permeability assays were performed, using a human nasal RPMI 2650 cell line in air–liquid interface. In vitro assays demonstrated that NLCs, including borneol (BorNLC), significantly increased escitalopram permeability (p < 0.01) and paroxetine recovery values (p < 0.05) in relation to the other formulations and non-encapsulated drugs. IN and intravenous (IV) pharmacokinetic studies performed in vivo with a single dose of 2.38 mg/kg demonstrated similar results for escitalopram brain-to-plasma ratios. IN administrations delayed escitalopram peak concentrations in the brain for 15–60 min and no direct nose-to-brain delivery was detected. However, encapsulation with BorNLC considerably decreased escitalopram exposure in the lungs (124 μg min/g) compared with free escitalopram by IN (168 μg min/g) and IV (321 μg min/g) routes. Surprisingly, BorNLC IN instillation increased concentration levels of paroxetine in the brain by five times and accelerated brain drug delivery. Once again, lung exposure was considerably lower with BorNLC (AUCt = 0.433 μg min/g) than that with IV administration (AUCt = 1.01 μg min/g) and non-encapsulated IN formulation (AUCt = 2.82 μg min/g). Direct nose-to-brain delivery was observed for paroxetine IN administration with a direct transport percentage (DTP) of 56.9%. If encapsulated, it increases to 74.2%. These results clearly emphasize that nose-to-brain delivery and lung exposure depend on the formulation and on the characteristics of the drug under investigation. NLCs seem to be an advantageous strategy for nose-to-brain delivery of lipophilic molecules, since they reduce systemic and lung exposure, thereby decreasing adverse effects. For hydrophilic compounds, NLCs are particularly important to decrease lung exposure after IN administration.
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Affiliation(s)
- Soraia Silva
- Laboratory of Pharmacology, Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal.,CIBIT-Coimbra Institute for Biomedical Imaging and Translational Research, University of Coimbra, Coimbra, Portugal
| | - Joana Bicker
- Laboratory of Pharmacology, Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal.,CIBIT-Coimbra Institute for Biomedical Imaging and Translational Research, University of Coimbra, Coimbra, Portugal
| | - Carla Fonseca
- Laboratory of Pharmacology, Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal.,CIBIT-Coimbra Institute for Biomedical Imaging and Translational Research, University of Coimbra, Coimbra, Portugal
| | - Nuno R Ferreira
- Laboratory of Pharmacology, Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal.,CIBIT-Coimbra Institute for Biomedical Imaging and Translational Research, University of Coimbra, Coimbra, Portugal
| | - Carla Vitorino
- Laboratory of Technology, Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal.,Coimbra Chemistry Center, Department of Chemistry, University of Coimbra, Coimbra, Portugal
| | - Gilberto Alves
- CICS-UBI-Health Sciences Research Centre, University of Beira Interior, Covilhã, Portugal
| | - Amílcar Falcão
- Laboratory of Pharmacology, Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal.,CIBIT-Coimbra Institute for Biomedical Imaging and Translational Research, University of Coimbra, Coimbra, Portugal
| | - Ana Fortuna
- Laboratory of Pharmacology, Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal.,CIBIT-Coimbra Institute for Biomedical Imaging and Translational Research, University of Coimbra, Coimbra, Portugal
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5
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Shoaib M, Giacopuzzi E, Pain O, Fabbri C, Magri C, Minelli A, Lewis CM, Gennarelli M. Investigating an in silico approach for prioritizing antidepressant drug prescription based on drug-induced expression profiles and predicted gene expression. THE PHARMACOGENOMICS JOURNAL 2020; 21:85-93. [PMID: 32943772 DOI: 10.1038/s41397-020-00186-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 08/13/2020] [Accepted: 09/08/2020] [Indexed: 11/09/2022]
Abstract
In clinical practice, an antidepressant prescription is a trial and error approach, which is time consuming and discomforting for patients. This study investigated an in silico approach for ranking antidepressants based on their hypothetical likelihood of efficacy. We predicted the transcriptomic profile of citalopram remitters by performing an in silico transcriptomic-wide association study on STAR*D GWAS data (N = 1163). The transcriptional profile of remitters was compared with 21 antidepressant-induced gene expression profiles in five human cell lines available in the connectivity-map database. Spearman correlation, Pearson correlation, and the Kolmogorov-Smirnov test were used to determine the similarity between antidepressant-induced profiles and remitter profiles, subsequently calculating the average rank of antidepressants across the three methods and a p value for each rank by using a permutation procedure. The drugs with the top ranks were those having a high positive correlation with the expression profiles of remitters and that may have higher chances of efficacy in the tested patients. In MCF7 (breast cancer cell line), escitalopram had the highest average rank, with an average rank higher than expected by chance (p = 0.0014). In A375 (human melanoma) and PC3 (prostate cancer) cell lines, escitalopram and citalopram emerged as the second-highest ranked antidepressants, respectively (p = 0.0310 and 0.0276, respectively). In HA1E (kidney) and HT29 (colon cancer) cell types, citalopram and escitalopram did not fall among top antidepressants. The correlation between citalopram remitters' and (es)citalopram-induced expression profiles in three cell lines suggests that our approach may be useful and with future improvements, it can be applicable at the individual level to tailor treatment prescription.
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Affiliation(s)
- Muhammad Shoaib
- Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy.,Social, Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, Psychology, and Neuroscience, King's College London, London, UK
| | - Edoardo Giacopuzzi
- National Institute for Health Research (NIHR), Oxford Biomedical Research Centre, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK.,IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy
| | - Oliver Pain
- Social, Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, Psychology, and Neuroscience, King's College London, London, UK
| | - Chiara Fabbri
- Social, Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, Psychology, and Neuroscience, King's College London, London, UK
| | - Chiara Magri
- Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | - Alessandra Minelli
- Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | - Cathryn M Lewis
- Social, Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, Psychology, and Neuroscience, King's College London, London, UK. .,Department of Medical and Molecular Genetics, Faculty of Life Sciences and Medicine, King's College London, London, UK.
| | - Massimo Gennarelli
- Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy.,IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy
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6
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Navratna V, Gouaux E. Insights into the mechanism and pharmacology of neurotransmitter sodium symporters. Curr Opin Struct Biol 2019; 54:161-170. [PMID: 30921707 DOI: 10.1016/j.sbi.2019.03.011] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 03/07/2019] [Accepted: 03/08/2019] [Indexed: 12/17/2022]
Abstract
Neurotransmitter sodium symporters (NSS) belong to the SLC6 family of solute carriers and play an essential role in neurotransmitter homeostasis throughout the body. In the past decade, structural studies employing bacterial orthologs of NSSs have provided insight into the mechanism of neurotransmitter transport. While the overall architecture of SLC6 transporters is conserved among species, in comparison to the bacterial homologs, the eukaryotic SLC6 family members harbor differences in amino acid sequence and molecular structure, which underpins their functional and pharmacological diversity, as well as their ligand specificity. Here, we review the structures and mechanisms of eukaryotic NSSs, focusing on the molecular basis for ligand recognition and on transport mechanism.
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Affiliation(s)
- Vikas Navratna
- Vollum Institute, Oregon Health & Science University, Portland, OR, United States
| | - Eric Gouaux
- Vollum Institute, Oregon Health & Science University, Portland, OR, United States; Howard Hughes Medical Institute, Oregon Health & Science University, Portland, OR, United States.
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7
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Ng I, Greenblatt HK, Greenblatt DJ. Stereo-Psychopharmacology: The Case of Citalopram and Escitalopram. Clin Pharmacol Drug Dev 2018; 5:331-5. [PMID: 27452501 DOI: 10.1002/cpdd.293] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Isaac Ng
- Tufts University School of Medicine, Boston, MA, USA
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8
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Roweth HG, Yan R, Bedwani NH, Chauhan A, Fowler N, Watson AH, Malcor JD, Sage SO, Jarvis GE. Citalopram inhibits platelet function independently of SERT-mediated 5-HT transport. Sci Rep 2018; 8:3494. [PMID: 29472624 PMCID: PMC5823918 DOI: 10.1038/s41598-018-21348-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Accepted: 02/01/2018] [Indexed: 11/09/2022] Open
Abstract
Citalopram prevents serotonin (5-HT) uptake into platelets by blocking the serotonin reuptake transporter (SERT). Although some clinical data suggest that selective serotonin reuptake inhibitors (SSRIs) may affect haemostasis and thrombosis, these poorly-characterised effects are not well understood mechanistically and useful in vitro data is limited. We sought to determine whether the inhibitory effects of citalopram on platelets are mediated via its pharmacological inhibition of 5-HT transport. We quantified the inhibitory potency of (RS)-, (R)- and (S)-citalopram on platelet function. If SERT blockade is the primary mechanism for citalopram-mediated platelet inhibition, these potencies should show quantitative congruence with inhibition of 5-HT uptake. Our data show that citalopram inhibits platelet aggregation, adhesion and thromboxane production with no difference in potency between (R)- and (S)-isomers. By contrast, citalopram had a eudysmic ratio of approximately 17 (S > R) for SERT blockade. Furthermore, nanomolar concentrations of citalopram inhibited 5-HT uptake into platelets but had no effect on other platelet functions, which were inhibited by micromolar concentrations. Our data indicate that citalopram-induced inhibition of platelets in vitro is not mediated by blockade of 5-HT transport. This raises a new question for future investigation: by what mechanism(s) does citalopram inhibit platelets?
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Affiliation(s)
- Harvey G Roweth
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, U.K
| | - Ruoling Yan
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, U.K
| | - Nader H Bedwani
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, U.K
| | - Alisha Chauhan
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, U.K
| | - Nicole Fowler
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, U.K
| | - Alice H Watson
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, U.K
| | | | - Stewart O Sage
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, U.K
| | - Gavin E Jarvis
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, U.K..
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Abstract
The dopamine (DAT), serotonin (SERT), and norepinephrine (NET) transporters, which are collectively referred to as monoamine transporters (MATs), play significant roles in regulating the neuronal response to these neurotransmitters. MATs terminate the action of these neurotransmitters by translocating them from the synaptic space into the presynaptic neurons. These three transmitters are responsible for controlling a number of physiological, emotional, and behavioral functions, with their transporters being the site of action of drugs employed for the treatment of a variety of conditions, including depression, anxiety, ADHD, schizophrenia, and psychostimulant abuse. Provided in this unit is information on the localization and regulation of MATs and the structural components of these proteins most responsible for the translocation process. Also included is a brief description of the evolution of ligands that interact with these transporters, as well as current theories concerning the pharmacological effects of substances that interact with these sites, including the molecular mechanisms of action of uptake inhibitors and allosteric modulators. Data relating to the presence, structure, and functions of allosteric modulators are included as well. The aim of this review is to provide background information on MATs to those who are new to this field, with a focus on the therapeutic potential of compounds that interact with these substrate transport sites. © 2017 by John Wiley & Sons, Inc.
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Affiliation(s)
- Shaili Aggarwal
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Pennsylvania
| | - Ole V Mortensen
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Pennsylvania
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10
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Topiol S, Bang-Andersen B, Sanchez C, Plenge P, Loland CJ, Juhl K, Larsen K, Bregnedal P, Bøgesø KP. X-ray structure based evaluation of analogs of citalopram: Compounds with increased affinity and selectivity compared with R-citalopram for the allosteric site (S2) on hSERT. Bioorg Med Chem Lett 2017; 27:470-478. [DOI: 10.1016/j.bmcl.2016.12.037] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Revised: 12/12/2016] [Accepted: 12/14/2016] [Indexed: 01/25/2023]
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Waider J, Ziegler J, Lau T. Outside the brain: an inside view on transgenic animal and stem cell-based models to examine neuronal serotonin-dependent regulation of HPA axis-controlled events during development and adult stages. Stem Cell Investig 2017; 3:94. [PMID: 28078274 DOI: 10.21037/sci.2016.11.12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 11/08/2016] [Indexed: 11/06/2022]
Abstract
Recently, Trista North and colleagues showed that neuronal synthesis of serotonin is an essential key process for embryonic hematopoietic stem (HPS) cell production in zebrafish. Using their experimental design, they were able to show that neuronal serotonin activates the stress-responsive hypothalamic-pituitary-adrenal (HPA) axis and glucocorticoid receptor activity which in turn induces HPS cell formation. In our perspective, we give a short overview on established experimental approaches for serotonergic neurotransmission in vivo and in vitro and their potential to address putative contributions of serotonergic neurotransmission to physiological processes beyond the central nervous systems (CNS). We briefly introduce common features of brain serotonin-depleted, tryptophan hydroxylase-2 knockout mice, which can be applied to investigate the contribution of brain-derived serotonin to developmental and adult physiological processes outside the CNS. These models allow to analyzing gender-specific, HPA axis-dependent processes in female and male knockout mice during developmental and adult stages. We also highlight the application of human and mouse stem cell-derived serotonergic neurons as an independent research model as well as complementary experimental approach to transgenic animal models. In case of human serotonergic neurotransmission, human in vitro-generated neurons present a very promising and highly valuable experimental approach to address characteristics of human neuronal serotonin signaling on a molecular and cellular level. The combination of transgenic animal models and newly established stem cell technologies will provide powerful research platforms, which will help to answer yet unsolved mysteries of serotonergic neurotransmission.
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Affiliation(s)
- Jonas Waider
- Division of Molecular Psychiatry, Center of Mental Health, University of Würzburg, Würzburg, Germany
| | - Janina Ziegler
- Central Institute of Mental Health, Hector Institute for Translational Brain Research, Medical Faculty Mannheim, University Heidelberg, Heidelberg, Germany
| | - Thorsten Lau
- Central Institute of Mental Health, Hector Institute for Translational Brain Research, Medical Faculty Mannheim, University Heidelberg, Heidelberg, Germany
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12
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Matthäus F, Haddjeri N, Sánchez C, Martí Y, Bahri S, Rovera R, Schloss P, Lau T. The allosteric citalopram binding site differentially interferes with neuronal firing rate and SERT trafficking in serotonergic neurons. Eur Neuropsychopharmacol 2016; 26:1806-1817. [PMID: 27665061 DOI: 10.1016/j.euroneuro.2016.09.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 07/10/2016] [Accepted: 09/01/2016] [Indexed: 10/21/2022]
Abstract
Citalopram is a clinically applied selective serotonin re-uptake inhibitor for antidepressant pharmacotherapy. It consists of two enantiomers, S-citalopram (escitalopram) and R-citalopram, of which escitalopram exerts the antidepressant therapeutic effect and has been shown to be one of the most efficient antidepressants, while R-citalopram antagonizes escitalopram via an unknown molecular mechanism that may depend on binding to a low-affinity allosteric binding site of the serotonin transporter. However, the precise mechanism of antidepressant regulation of the serotonin transporter by citalopram enantiomers still remains elusive. Here we investigate escitalopram׳s acute effect on (1) serotonergic neuronal firing in transgenic mice that express the human serotonin transporter without and with a mutation that disables the allosteric binding site, and (2) regulation of the serotonin transporter׳s cell surface localization in stem cell-derived serotonergic neurons. Our results demonstrate that escitalopram inhibited neuronal firing less potently in the mouse line featuring a mutation that abolishes the function of the allosteric binding site and induced serotonin transporter internalization independently of the allosteric binding site mechanism. Furthermore, citalopram enantiomers dose-dependently induced serotonin transporter internalization. In conclusion, this study provides new insight into antidepressant effects exerted by citalopram enantiomers in presence and absence of a functional allosteric binding site.
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Affiliation(s)
- Friederike Matthäus
- Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Department Psychiatry and Psychotherapy, Biochemical Laboratory, Mannheim, Germany
| | - Nasser Haddjeri
- Univ Lyon, Université Claude Bernard Lyon 1, Inserm, Stem Cell and Brain Research Institute U1208, 69500 Bron, France
| | - Connie Sánchez
- Sourcing and Scientific Excellence at Lundbeck Research USA, Inc., Paramus, NJ, USA
| | - Yasmina Martí
- Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Department Psychiatry and Psychotherapy, Biochemical Laboratory, Mannheim, Germany
| | - Senda Bahri
- Univ Lyon, Université Claude Bernard Lyon 1, Inserm, Stem Cell and Brain Research Institute U1208, 69500 Bron, France
| | - Renaud Rovera
- Univ Lyon, Université Claude Bernard Lyon 1, Inserm, Stem Cell and Brain Research Institute U1208, 69500 Bron, France
| | - Patrick Schloss
- Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Department Psychiatry and Psychotherapy, Biochemical Laboratory, Mannheim, Germany
| | - Thorsten Lau
- Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Department Psychiatry and Psychotherapy, Biochemical Laboratory, Mannheim, Germany.
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13
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The norepinephrine reuptake inhibitor reboxetine is more potent in treating murine narcoleptic episodes than the serotonin reuptake inhibitor escitalopram. Behav Brain Res 2016; 308:205-10. [DOI: 10.1016/j.bbr.2016.04.033] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Revised: 04/13/2016] [Accepted: 04/18/2016] [Indexed: 12/18/2022]
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Abstract
INTRODUCTION The initial decades of the 21st century have witnessed striking technical advances that have made it possible to detect, identify and quantitatively measure large numbers of plasma or tissue metabolites. In parallel, similar advances have taken place in our ability to sequence DNA and RNA. Those advances have moved us beyond studies of single metabolites and single genetic polymorphisms to the study of hundreds or thousands of metabolites and millions of genomic variants in a single cell or subject. It is now possible to merge and integrate large data sets generated by the use of different "-omics" techniques to increase our understanding of the molecular basis for variation in disease risk and/or drug response phenotypes. OBJECTIVES This "Brief Review" will outline some of the challenges and opportunities associated with studies in which metabolomic data have been merged with genomics in an attempt to gain novel insight into mechanisms associated with variation in drug response phenotypes, with an emphasis on the application of a pharmacometabolomics-informed pharmacogenomic research strategy and with selected examples of the application of that strategy. METHODS Studies that used pharmacometabolomics to inform and guide pharmacogenomics were reviewed. Clinical studies that were used as the basis for pharmacometabolomics-informed pharmacogenomic studies, published in five independent manuscripts, are described briefly. RESULTS Within these five manuscripts, both pharmacokinetic and pharmacodynamic metabolomics approaches were used. Candidate gene and genome-wide approaches that were used in concert with these metabolomic data identified novel metabolite-gene relationships that were associated with drug response phenotypes in these pharmacometabolomics-informed pharmacogenomics studies. CONCLUSION This "Brief Review" outlines the emerging discipline of pharmacometabolomics-informed pharmacogenomics in which metabolic profiles are associated with both clinical phenotypes and genetic variants to identify novel genetic variants associated with drug response phenotypes based on metabolic profiles.
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Affiliation(s)
- Drew Neavin
- Department of Molecular Pharmacology and Experimental Therapeutics, 200 First Street SW, Mayo Clinic, Rochester, MN 55905
| | - Rima Kaddurah-Daouk
- Department of Psychiatry and Behavioral Medicine, Duke Institute for Brain Sciences, 3552, Blue Zone, Duke South, Durham, NC 27710
| | - Richard Weinshilboum
- Department of Molecular Pharmacology and Experimental Therapeutics, 200 First Street SW, Mayo Clinic, Rochester, MN 55905
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Coleman JA, Green EM, Gouaux E. X-ray structures and mechanism of the human serotonin transporter. Nature 2016; 532:334-9. [PMID: 27049939 PMCID: PMC4898786 DOI: 10.1038/nature17629] [Citation(s) in RCA: 438] [Impact Index Per Article: 54.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Accepted: 02/29/2016] [Indexed: 12/19/2022]
Abstract
The serotonin transporter (SERT) terminates serotonergic signaling through the sodium and chloride dependent reuptake of neurotransmitter into presynaptic neurons. SERT is a target for antidepressant and psychostimulant drugs, which block reuptake and prolong neurotransmitter signaling. Here we report x-ray crystallographic structures of human SERT at 3.15 Å resolution bound to the antidepressants (S)-citalopram or paroxetine. Antidepressants lock SERT in an outward-open conformation by lodging in the central binding site, located between transmembrane helices 1, 3, 6, 8, and 10, directly blocking serotonin binding. We further identify the location of an allosteric site in the complex as residing at the periphery of the extracellular vestibule, interposed between extracellular loops 4 and 6 and TMs 1, 6, 10, and 11. Occupancy of the allosteric site sterically hinders ligand unbinding from the central site, providing an explanation for the action of (S)-citalopram as an allosteric ligand. These structures define the mechanism of antidepressant action in SERT and provide blueprints for future drug design.
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Affiliation(s)
- Jonathan A Coleman
- Vollum Institute, Oregon Health &Science University, Portland, Oregon 97239, USA
| | - Evan M Green
- Vollum Institute, Oregon Health &Science University, Portland, Oregon 97239, USA
| | - Eric Gouaux
- Vollum Institute, Oregon Health &Science University, Portland, Oregon 97239, USA.,Howard Hughes Medical Institute, Oregon Health &Science University, Portland, Oregon 97239, USA
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Larsen MAB, Plenge P, Andersen J, Eildal JNN, Kristensen AS, Bøgesø KP, Gether U, Strømgaard K, Bang-Andersen B, Loland CJ. Structure-activity relationship studies of citalopram derivatives: examining substituents conferring selectivity for the allosteric site in the 5-HT transporter. Br J Pharmacol 2016; 173:925-36. [PMID: 26699847 DOI: 10.1111/bph.13411] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 12/10/2015] [Accepted: 12/14/2015] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND AND PURPOSE The 5-HT transporter (SERT) is a target for antidepressant drugs. SERT possesses two binding sites: the orthosteric (S1) binding site, which is the presumed target for current SERT inhibitors, and an allosteric (S2) site for which potential therapeutic effects are unknown. The antidepressant drug citalopram displays high-affinity S1 binding and low-affinity S2 binding. To elucidate a possible therapeutic role of allosteric inhibition of SERT, a drug that specifically targets the allosteric site is required. The purpose of this study was to find a compound having higher selectivity towards the S2 site. EXPERIMENTAL APPROACH We performed a systematic structure-activity relationship study based on the scaffold of citalopram and the structurally closely related congener, talopram, which shows low-affinity S1 binding in SERT. The role of the four chemical substituents, which distinguish citalopram from talopram in conferring selectivity towards the S1 and S2 site, respectively, was assessed by determining the binding of 14 citalopram/talopram analogous to the S1 and S2 binding sites in SERT using membranes of COS7 cells transiently expressing SERT. KEY RESULTS The structure-activity relationship study revealed that dimethyl citalopram possesses the highest affinity for the allosteric site relative to the S1 site in SERT and has approximately twofold selectivity for the allosteric site relative to the S1 site in SERT. CONCLUSIONS AND IMPLICATIONS The compound could be a useful lead for future synthesis of drugs with high affinity and high selectivity towards the allosteric binding site.
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Affiliation(s)
- M Andreas B Larsen
- Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Per Plenge
- Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jacob Andersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jonas N N Eildal
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Anders S Kristensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Klaus P Bøgesø
- Neuroscience Drug Discovery, H. Lundbeck A/S, Valby, Denmark
| | - Ulrik Gether
- Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Kristian Strømgaard
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Benny Bang-Andersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Neuroscience Drug Discovery, H. Lundbeck A/S, Valby, Denmark
| | - Claus J Loland
- Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Murray KE, Ressler KJ, Owens MJ. In vivo investigation of escitalopram's allosteric site on the serotonin transporter. Pharmacol Biochem Behav 2015; 141:50-7. [PMID: 26621784 DOI: 10.1016/j.pbb.2015.11.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2015] [Revised: 11/20/2015] [Accepted: 11/23/2015] [Indexed: 10/22/2022]
Abstract
Escitalopram is a commonly prescribed antidepressant of the selective serotonin reuptake inhibitor class. Clinical evidence and mapping of the serotonin transporter (SERT) identified that escitalopram, in addition to its binding to a primary uptake-blocking site, is capable of binding to the SERT via an allosteric site that is hypothesized to alter escitalopram's kinetics at the SERT. The studies reported here examined the in vivo role of the SERT allosteric site in escitalopram action. A knockin mouse model that possesses an allosteric-null SERT was developed. Autoradiographic studies indicated that the knockin protein was expressed at a lower density than endogenous mouse SERT (approximately 10-30% of endogenous mouse SERT), but the knockin mice are a viable tool to study the allosteric site. Microdialysis studies in the ventral hippocampus found no measurable decrease in extracellular serotonin response after local escitalopram challenge in mice without the allosteric site compared to mice with the site (p=0.297). In marble burying assays there was a modest effect of the absence of the allosteric site, with a larger systemic dose of escitalopram (10-fold) necessary for the same effect as in mice with intact SERT (p=0.023). However, there was no effect of the allosteric site in the tail suspension test. Together these data suggest that there may be a regional specificity in the role of the allosteric site. The lack of a robust effect overall suggests that the role of the allosteric site for escitalopram on the SERT may not produce meaningful in vivo effects.
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Affiliation(s)
- Karen E Murray
- Laboratory of Neuropsychopharmacology, 101 Woodruff Circle, Suite 4000, Department of Psychiatry and Behavioral Sciences, Emory University, Atlanta, GA 30322, United States
| | - Kerry J Ressler
- Laboratory of Molecular Neurobiology of Fear, 101 Woodruff Circle, Suite 4000, Department of Psychiatry and Behavioral Sciences, Emory University, Atlanta, GA 30322, United States
| | - Michael J Owens
- Laboratory of Neuropsychopharmacology, 101 Woodruff Circle, Suite 4000, Department of Psychiatry and Behavioral Sciences, Emory University, Atlanta, GA 30322, United States.
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