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Mayer FP, Stewart A, Blakely RD. Leaky lessons learned: Efflux prone dopamine transporter variant reveals sex and circuit specific contributions of D2 receptor signalling to neuropsychiatric disease. Basic Clin Pharmacol Toxicol 2024; 134:206-218. [PMID: 37987120 DOI: 10.1111/bcpt.13964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 11/14/2023] [Accepted: 11/17/2023] [Indexed: 11/22/2023]
Abstract
Aberrant dopamine (DA) signalling has been implicated in various neuropsychiatric disorders, including attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorder (ASD), schizophrenia, bipolar disorder (BPD) and addiction. The availability of extracellular DA is sculpted by the exocytotic release of vesicular DA and subsequent transporter-mediated clearance, rendering the presynaptic DA transporter (DAT) a crucial regulator of DA neurotransmission. D2-type DA autoreceptors (D2ARs) regulate multiple aspects of DA homeostasis, including (i) DA synthesis, (ii) vesicular release, (iii) DA neuron firing and (iv) the surface expression of DAT and DAT-mediated DA clearance. The DAT Val559 variant, identified in boys with ADHD or ASD, as well as in a girl with BPD, supports anomalous DA efflux (ADE), which we have shown drives tonic activation of D2ARs. Through ex vivo and in vivo studies of the DAT Val559 variant using transgenic knock-in mice, we have uncovered a circuit and sex-specific capacity of D2ARs to regulate DAT, which consequently disrupts DA signalling and behaviour differently in males and females. Our studies reveal the ability of the construct-valid DAT Val559 model to elucidate endogenous mechanisms that support DA signalling, findings that may be of translational and/or therapeutic importance.
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Affiliation(s)
- Felix P Mayer
- Department of Biomedical Science, Florida Atlantic University, Jupiter, Florida, USA
- Stiles-Nicholson Brain Institute, Florida Atlantic University, Jupiter, Florida, USA
| | - Adele Stewart
- Department of Biomedical Science, Florida Atlantic University, Jupiter, Florida, USA
- Stiles-Nicholson Brain Institute, Florida Atlantic University, Jupiter, Florida, USA
| | - Randy D Blakely
- Department of Biomedical Science, Florida Atlantic University, Jupiter, Florida, USA
- Stiles-Nicholson Brain Institute, Florida Atlantic University, Jupiter, Florida, USA
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2
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Gopinath A, Riaz T, Miller E, Phan L, Smith A, Syed O, Franks S, Martinez LR, Khoshbouei H. Methamphetamine induces a low dopamine transporter expressing state without altering the total number of peripheral immune cells. Basic Clin Pharmacol Toxicol 2023; 133:496-507. [PMID: 36710070 PMCID: PMC10382601 DOI: 10.1111/bcpt.13838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 01/22/2023] [Accepted: 01/24/2023] [Indexed: 01/31/2023]
Abstract
Methamphetamine is a widely abused psychostimulant and one of the main targets of dopamine transporter (DAT). Methamphetamine reduces DAT-mediated dopamine uptake and stimulates dopamine efflux leading to increased synaptic dopamine levels many folds above baseline. Methamphetamine also targets DAT-expressing peripheral immune cells, reduces wound healing and increases infection susceptibility. Peripheral immune cells such as myeloid cells, B cells and T cells express DAT. DAT activity on monocytes and macrophages exhibits immune suppressive properties via an autocrine paracrine mechanism, where deletion or inhibition of DAT activity increases inflammatory responses. In this study, utilizing a mouse model of daily single dose of methamphetamine administration, we investigated the impact of the drug on DAT expression in peripheral immune cells. We found in methamphetamine-treated mice that DAT expression was down-regulated in most of the innate and adaptive immune cells. Methamphetamine did not increase or decrease the total number of innate and adaptive immune cells but changed their immunophenotype to low-DAT-expressing phenotype. Moreover, serum cytokine distributions were altered in methamphetamine-treated mice. Therefore, resembling its effect in the CNS, in the periphery, methamphetamine regulates DAT expression on peripheral immune cell subsets, potentially describing methamphetamine regulation of peripheral immunity.
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Affiliation(s)
- Adithya Gopinath
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Tabish Riaz
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Emily Miller
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Leah Phan
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Aidan Smith
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Ohee Syed
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Stephen Franks
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Luis R Martinez
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, Florida, USA
- Emerging Pathogens Institute, University of Florida, Gainesville, Florida, USA
- Center for Immunology and Transplantation, University of Florida, Gainesville, Florida, USA
- Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, Florida, USA
| | - Habibeh Khoshbouei
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, Florida, USA
- Center for Immunology and Transplantation, University of Florida, Gainesville, Florida, USA
- Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, Florida, USA
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3
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Miller EJ, Khoshbouei H. Immunity on ice: The impact of methamphetamine on peripheral immunity. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2023; 99:217-250. [PMID: 38467482 DOI: 10.1016/bs.apha.2023.09.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/13/2024]
Abstract
Methamphetamine (METH) regulation of the dopamine transporter (DAT) and central nervous system (CNS) dopamine transmission have been extensively studied. However, our understanding of how METH influences neuroimmune communication and innate and adaptive immunity is still developing. Recent studies have shed light on the bidirectional communication between the CNS and the peripheral immune system. They have established a link between CNS dopamine levels, dopamine neuronal activity, and peripheral immunity. Akin to dopamine neurons in the CNS, a majority of peripheral immune cells also express DAT, implying that in addition to their effect in the CNS, DAT ligands such as methamphetamine may have a role in modulating peripheral immunity. For example, by directly influencing DAT-expressing peripheral immune cells and thus peripheral immunity, METH can trigger a feed-forward cascade that impacts the bidirectional communication between the CNS and peripheral immune system. In this review, we aim to discuss the current understanding of how METH modulates both innate and adaptive immunity and identify areas where knowledge gaps exist. These gaps will then be considered in guiding future research directions.
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Affiliation(s)
- Emily J Miller
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, FL, United States.
| | - Habibeh Khoshbouei
- Department of Neuroscience, University of Florida College of Medicine, Gainesville, FL, United States.
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4
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Shekar A, Mabry SJ, Cheng MH, Aguilar JI, Patel S, Zanella D, Saleeby DP, Zhu Y, Romanazzi T, Ulery-Reynolds P, Bahar I, Carter AM, Matthies HJG, Galli A. Syntaxin 1 Ser 14 phosphorylation is required for nonvesicular dopamine release. SCIENCE ADVANCES 2023; 9:eadd8417. [PMID: 36630507 PMCID: PMC9833662 DOI: 10.1126/sciadv.add8417] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Accepted: 12/14/2022] [Indexed: 05/30/2023]
Abstract
Amphetamine (AMPH) is a psychostimulant that is commonly abused. The stimulant properties of AMPH are associated with its ability to increase dopamine (DA) neurotransmission. This increase is promoted by nonvesicular DA release mediated by reversal of DA transporter (DAT) function. Syntaxin 1 (Stx1) is a SNARE protein that is phosphorylated at Ser14 by casein kinase II. We show that Stx1 phosphorylation is critical for AMPH-induced nonvesicular DA release and, in Drosophila melanogaster, regulates the expression of AMPH-induced preference and sexual motivation. Our molecular dynamics simulations of the DAT/Stx1 complex demonstrate that phosphorylation of these proteins is pivotal for DAT to dwell in a DA releasing state. This state is characterized by the breakdown of two key salt bridges within the DAT intracellular gate, causing the opening and hydration of the DAT intracellular vestibule, allowing DA to bind from the cytosol, a mechanism that we hypothesize underlies nonvesicular DA release.
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Affiliation(s)
- Aparna Shekar
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Samuel J. Mabry
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Mary H. Cheng
- Department of Computational and Systems Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Jenny I. Aguilar
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Shalin Patel
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Daniele Zanella
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA
| | - David P. Saleeby
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Yanqi Zhu
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Tiziana Romanazzi
- Department of Biotechnology and Life Sciences, University of Insubria, Varese, Italy
| | | | - Ivet Bahar
- Department of Computational and Systems Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Angela M. Carter
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA
| | | | - Aurelio Galli
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA
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Miller DR, Bu AM, Gopinath A, Martinez LR, Khoshbouei H. Methamphetamine dysregulation of the central nervous system and peripheral immunity. J Pharmacol Exp Ther 2021; 379:372-385. [PMID: 34535563 DOI: 10.1124/jpet.121.000767] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 09/16/2021] [Indexed: 11/22/2022] Open
Abstract
Methamphetamine (METH) is a potent psychostimulant that increases extracellular monoamines such as dopamine and norepinephrine and affects multiple tissue and cell types. The reinforcing properties of METH underlie its significant abuse potential and dysregulation of peripheral immunity and central nervous system functions. Together, the constellation of METH's effects on cellular targets and regulatory processes have shown to lead to immune suppression and neurodegeneration in METH addicts and animal models of METH exposure. Here we extensively review many of the cell types and mechanisms of METH-induced dysregulation of the central nervous system and peripheral immune system. Significance Statement Emerging research has begun to show that methamphetamine not only regulates dopaminergic neuronal activity, it also affects non-neuronal brain cells, such as microglia and astrocytes as well immunological cells of the periphery. The bi-directional communication between dopaminergic neurons in the CNS and peripheral immune cells becomes dysregulated by a constellation of dysfunctional neuronal and cell types revealing multiple targets that must be considered at the interface between basic and clinical neuroscience.
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Affiliation(s)
| | | | - Adithya Gopinath
- Department of Neuroscience, University of Florida, United States
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6
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Miller DR, Guenther DT, Maurer AP, Hansen CA, Zalesky A, Khoshbouei H. Dopamine Transporter Is a Master Regulator of Dopaminergic Neural Network Connectivity. J Neurosci 2021; 41:5453-5470. [PMID: 33980544 PMCID: PMC8221606 DOI: 10.1523/jneurosci.0223-21.2021] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 04/19/2021] [Accepted: 05/01/2021] [Indexed: 12/13/2022] Open
Abstract
Dopaminergic neurons of the substantia nigra pars compacta (SNC) and ventral tegmental area (VTA) exhibit spontaneous firing activity. The dopaminergic neurons in these regions have been shown to exhibit differential sensitivity to neuronal loss and psychostimulants targeting dopamine transporter. However, it remains unclear whether these regional differences scale beyond individual neuronal activity to regional neuronal networks. Here, we used live-cell calcium imaging to show that network connectivity greatly differs between SNC and VTA regions with higher incidence of hub-like neurons in the VTA. Specifically, the frequency of hub-like neurons was significantly lower in SNC than in the adjacent VTA, consistent with the interpretation of a lower network resilience to SNC neuronal loss. We tested this hypothesis, in DAT-cre/loxP-GCaMP6f mice of either sex, when activity of an individual dopaminergic neuron is suppressed, through whole-cell patch clamp electrophysiology, in either SNC or VTA networks. Neuronal loss in the SNC increased network clustering, whereas the larger number of hub-neurons in the VTA overcompensated by decreasing network clustering in the VTA. We further show that network properties are regulatable via a dopamine transporter but not a D2 receptor dependent mechanism. Our results demonstrate novel regulatory mechanisms of functional network topology in dopaminergic brain regions.SIGNIFICANCE STATEMENT In this work, we begin to untangle the differences in complex network properties between the substantia nigra pars compacta (SNC) and VTA, that may underlie differential sensitivity between regions. The methods and analysis employed provide a springboard for investigations of network topology in multiple deep brain structures and disorders.
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Affiliation(s)
- Douglas R Miller
- Department of Neuroscience, University of Florida, Gainesville, Florida
| | - Dylan T Guenther
- Department of Neuroscience, University of Florida, Gainesville, Florida
| | - Andrew P Maurer
- Department of Neuroscience, University of Florida, Gainesville, Florida
| | - Carissa A Hansen
- Department of Neuroscience, University of Florida, Gainesville, Florida
| | - Andrew Zalesky
- Melbourne Neuropsychiatry Centre, The University of Melbourne and Melbourne Health, Melbourne, Victoria 3010, Australia
- Department of Biomedical Engineering, Melbourne School of Engineering, The University of Melbourne, Melbourne, Victoria 3010, Australia
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7
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Hersey M, Bacon AK, Bailey LG, Coggiano MA, Newman AH, Leggio L, Tanda G. Psychostimulant Use Disorder, an Unmet Therapeutic Goal: Can Modafinil Narrow the Gap? Front Neurosci 2021; 15:656475. [PMID: 34121988 PMCID: PMC8187604 DOI: 10.3389/fnins.2021.656475] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 04/20/2021] [Indexed: 12/11/2022] Open
Abstract
The number of individuals affected by psychostimulant use disorder (PSUD) has increased rapidly over the last few decades resulting in economic, emotional, and physical burdens on our society. Further compounding this issue is the current lack of clinically approved medications to treat this disorder. The dopamine transporter (DAT) is a common target of psychostimulant actions related to their use and dependence, and the recent availability of atypical DAT inhibitors as a potential therapeutic option has garnered popularity in this research field. Modafinil (MOD), which is approved for clinical use for the treatment of narcolepsy and sleep disorders, blocks DAT just like commonly abused psychostimulants. However, preclinical and clinical studies have shown that it lacks the addictive properties (in both behavioral and neurochemical studies) associated with other abused DAT inhibitors. Clinical availability of MOD has facilitated its off-label use for several psychiatric disorders related to alteration of brain dopamine (DA) systems, including PSUD. In this review, we highlight clinical and preclinical research on MOD and its R-enantiomer, R-MOD, as potential medications for PSUD. Given the complexity of PSUD, we have also reported the effects of MOD on psychostimulant-induced appearance of several symptoms that could intensify the severity of the disease (i.e., sleep disorders and impairment of cognitive functions), besides the potential therapeutic effects of MOD on PSUD.
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Affiliation(s)
- Melinda Hersey
- Medication Development Program, Molecular Targets and Medication Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, United States
| | - Amanda K. Bacon
- Medication Development Program, Molecular Targets and Medication Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, United States
| | - Lydia G. Bailey
- Medication Development Program, Molecular Targets and Medication Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, United States
| | - Mark A. Coggiano
- Medication Development Program, Molecular Targets and Medication Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, United States
| | - Amy H. Newman
- Medication Development Program, Molecular Targets and Medication Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, United States
| | - Lorenzo Leggio
- Medication Development Program, Molecular Targets and Medication Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, United States
- Clinical Psychoneuroendo- crinology and Neuropsychopharmacology Section, Translational Addiction Medicine Branch, National Institute on Drug Abuse Intramural Research Program, National Institutes of Health, Baltimore, MD, United States
- National Institute on Alcohol Abuse and Alcoholism, Division of Intramural Clinical and Biological Research, National Institutes of Health, Bethesda, MD, United States
| | - Gianluigi Tanda
- Medication Development Program, Molecular Targets and Medication Discovery Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, United States
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Docherty JR, Alsufyani HA. Cardiovascular and temperature adverse actions of stimulants. Br J Pharmacol 2021; 178:2551-2568. [PMID: 33786822 DOI: 10.1111/bph.15465] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 02/22/2021] [Accepted: 03/10/2021] [Indexed: 12/11/2022] Open
Abstract
The vast majority of illicit stimulants act at monoaminergic systems, causing both psychostimulant and adverse effects. Stimulants can interact as substrates or antagonists at the nerve terminal monoamine transporter that mediates the reuptake of monoamines across the nerve synaptic membrane and at the vesicular monoamine transporter (VMAT-2) that mediates storage of monoamines in vesicles. Stimulants can act directly at presynaptic or postsynaptic receptors for monoamines or have indirect monoamine-mimetic actions due to the release of monoamines. Cocaine and other stimulants can acutely increase the risk of sudden cardiac death. Stimulants, particularly MDMA, in hot conditions, such as that occurring at a "rave," have caused fatalities from the consequences of hyperthermia, often compounding cardiac adverse actions. This review examines the pharmacology of the cardiovascular and temperature adverse actions of stimulants.
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Affiliation(s)
- James R Docherty
- Department of Physiology, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Hadeel A Alsufyani
- Department of Physiology, King Abdulaziz University, Jeddah, Saudi Arabia
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9
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Underhill SM, Amara SG. Acetylcholine Receptor Stimulation Activates Protein Kinase C Mediated Internalization of the Dopamine Transporter. Front Cell Neurosci 2021; 15:662216. [PMID: 33897375 PMCID: PMC8062973 DOI: 10.3389/fncel.2021.662216] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Accepted: 03/11/2021] [Indexed: 11/13/2022] Open
Abstract
The dopamine transporter (DAT) clears neurotransmitters from the extracellular space and serves as an important regulator of signal amplitude and duration at sites of dopamine release. Several different intracellular signaling pathways have been observed to modulate DAT activity through the regulation of the trafficking of the carriers to and from the cell surface. Acute activation of protein kinase C (PKC) by phorbol esters facilitates clathrin-dependent internalization of the DAT in a variety of model systems; however, the physiological stimuli and cell-surface receptor systems that activate PKC and regulate the DAT in dopamine neurons remain elusive. We report here that stimulation of M1/M5 muscarinic receptors in midbrain cultures decreases the ability of dopamine neurons to transport dopamine through DAT. Application of the cholinomimetic drug carbachol leads to a decrease in DAT activity in primary cultures while the M1/M5-specific antagonist, pirenzepine, blocks these effects. The M3 antagonist, DAU 5884, does not affect, but a positive modulator of M5, VU 0238429, enhances the loss of DAT function in response to carbachol and acetylcholine. These data implicate M1/M5 receptors on dopamine neurons in the modulation of DAT function. Bisindolylmaleimide, a PKC inhibitor, blocks the effects of carbachol stimulation on dopamine uptake, supporting a role for PKC in muscarinic receptor-mediated DAT internalization. Furthermore, as shown previously for PKC-induced internalization, downregulation of the DAT is dependent on both clathrin and dynamin. A Gq-specific inhibitor peptide also blocks the effects of carbachol on DAT in primary cultures, confirming Gq as the G-protein that couples M1/M5 receptors to PKC activation in these cells. In acute midbrain slices, biotinylation of cell-surface proteins revealed the loss of dopamine transport mediated by muscarinic receptor stimulation was, indeed, due to loss of membrane expression of the DAT in endogenous tissue. These data indicate that stimulation of cholinergic pathways can lead to modulation of dopamine through internalization of the DAT.
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Affiliation(s)
- Suzanne M Underhill
- National Institute of Mental Health, National Institutes of Health (NIH), Bethesda, MD, United States
| | - Susan G Amara
- National Institute of Mental Health, National Institutes of Health (NIH), Bethesda, MD, United States
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10
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Jones SR, Fordahl SC. Bingeing on High-Fat Food Enhances Evoked Dopamine Release and Reduces Dopamine Uptake in the Nucleus Accumbens. Obesity (Silver Spring) 2021; 29:721-730. [PMID: 33660412 PMCID: PMC8048651 DOI: 10.1002/oby.23122] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 12/15/2020] [Accepted: 12/17/2020] [Indexed: 11/24/2022]
Abstract
OBJECTIVE Binge-eating disorder (BED) disrupts dopamine neuron function, in part by altering dopamine transporter (DAT) activity. This study characterized the effects of high-fat bingeing on presynaptic dopamine terminals and tested the hypothesis that acute low-dose amphetamine would restore DAT function. METHODS C57BL/6 mice were given limited access (LimA) to a high-fat diet (2 h/d, 3 d/wk) or standard chow (control). After 6 weeks, ex vivo fast-scan cyclic voltammetry was used to characterize dopamine-terminal adaptations in the nucleus accumbens. Prior to undergoing fast-scan cyclic voltammetry, some mice from each group were given amphetamine (0.5 mg/kg intraperitoneally). RESULTS Escalation of high fat intake, termed bingeing, occurred in the LimA group and coincided with increased phasic dopamine release, reduced dopamine uptake rates, and increased dopamine receptor 2 (D2 ) autoreceptor function. Acute amphetamine selectively reversed dopamine uptake changes in the LimA group and restored the potency of amphetamine to inhibit uptake. CONCLUSIONS High-fat bingeing enhanced dopaminergic signaling in the nucleus accumbens by promoting phasic dopamine release and reducing clearance. This study's data show that amphetamine was efficacious in restoring impaired DAT function caused by high-fat bingeing but did not reduce dopamine release to normal. These presynaptic changes should be considered if amphetamine-like dopamine releasers are used as treatments for BED.
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Affiliation(s)
- Sara R. Jones
- Department of Physiology and PharmacologySchool of MedicineWake Forest UniversityWinston‐SalemNorth CarolinaUSA
| | - Steve C. Fordahl
- Department of NutritionUNC GreensboroGreensboroNorth CarolinaUSA
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11
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Dynamic control of the dopamine transporter in neurotransmission and homeostasis. NPJ Parkinsons Dis 2021; 7:22. [PMID: 33674612 PMCID: PMC7935902 DOI: 10.1038/s41531-021-00161-2] [Citation(s) in RCA: 55] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Accepted: 01/08/2021] [Indexed: 01/31/2023] Open
Abstract
The dopamine transporter (DAT) transports extracellular dopamine into the intracellular space contributing to the regulation of dopamine neurotransmission. A reduction of DAT density is implicated in Parkinson's disease (PD) by neuroimaging; dopamine turnover is dopamine turnover is elevated in early symptomatic PD and in presymptomatic individuals with monogenic mutations causal for parkinsonism. As an integral plasma membrane protein, DAT surface expression is dynamically regulated through endocytic trafficking, enabling flexible control of dopamine signaling in time and space, which in turn critically modulates movement, motivation and learning behavior. Yet the cellular machinery and functional implications of DAT trafficking remain enigmatic. In this review we summarize mechanisms governing DAT trafficking under normal physiological conditions and discuss how PD-linked mutations may disturb DAT homeostasis. We highlight the complexity of DAT trafficking and reveal DAT dysregulation as a common theme in genetic models of parkinsonism.
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12
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Amphetamines signal through intracellular TAAR1 receptors coupled to Gα 13 and Gα S in discrete subcellular domains. Mol Psychiatry 2021; 26:1208-1223. [PMID: 31399635 PMCID: PMC7038576 DOI: 10.1038/s41380-019-0469-2] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 04/23/2019] [Accepted: 05/03/2019] [Indexed: 12/11/2022]
Abstract
The extensive use of amphetamines to treat attention deficit hyperactivity disorders in children provides a compelling rationale for understanding the mechanisms of action of amphetamines and amphetamine-related drugs. We have previously shown that acute amphetamine (AMPH) regulates the trafficking of both dopamine and glutamate transporters in dopamine neurons by increasing activation of the small GTPase RhoA and of protein kinase A. Here we demonstrate that these downstream signaling events depend upon the direct activation of a trace amine-associated receptor, TAAR1, an intracellular G-protein coupled receptor (GPCR) that can be activated by amphetamines, trace amines, and biogenic amine metabolites. Using cell lines and mouse lines in which TAAR1 expression has been disrupted, we demonstrate that TAAR1 mediates the effects of AMPH on both RhoA and cAMP signaling. Inhibition of different Gα signaling pathways in cell lines and in vivo using small cell-permeable peptides confirms that the endogenous intracellular TAAR1 couples to G13 and to GS α-subunits to increase RhoA and PKA activity, respectively. Results from experiments with RhoA- and PKA-FRET sensors targeted to different subcellular compartments indicate that AMPH-elicited PKA activation occurs throughout the cell, whereas G13-mediated RhoA activation is concentrated near the endoplasmic reticulum. These observations define TAAR1 as an obligate intracellular target for amphetamines in dopamine neurons and support a model in which distinct pools of TAAR1 mediate the activation of signaling pathways in different compartments to regulate excitatory and dopaminergic neurotransmission.
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13
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Wei Y, Shah R. Substance Use Disorder in the COVID-19 Pandemic: A Systematic Review of Vulnerabilities and Complications. Pharmaceuticals (Basel) 2020; 13:E155. [PMID: 32708495 PMCID: PMC7407364 DOI: 10.3390/ph13070155] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 07/15/2020] [Accepted: 07/16/2020] [Indexed: 01/18/2023] Open
Abstract
As the world endures the coronavirus disease 2019 (COVID-19) pandemic, the conditions of 35 million vulnerable individuals struggling with substance use disorders (SUDs) worldwide have not received sufficient attention for their special health and medical needs. Many of these individuals are complicated by underlying health conditions, such as cardiovascular and lung diseases and undermined immune systems. During the pandemic, access to the healthcare systems and support groups is greatly diminished. Current research on COVID-19 has not addressed the unique challenges facing individuals with SUDs, including the heightened vulnerability and susceptibility to the disease. In this systematic review, we will discuss the pathogenesis and pathology of COVID-19, and highlight potential risk factors and complications to these individuals. We will also provide insights and considerations for COVID-19 treatment and prevention in patients with SUDs.
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Affiliation(s)
- Yufeng Wei
- Department of Chemistry, New Jersey City University, Jersey City, NJ 07305, USA;
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14
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Fagan RR, Kearney PJ, Melikian HE. In Situ Regulated Dopamine Transporter Trafficking: There's No Place Like Home. Neurochem Res 2020; 45:1335-1343. [PMID: 32146647 DOI: 10.1007/s11064-020-03001-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 02/24/2020] [Accepted: 02/26/2020] [Indexed: 12/13/2022]
Abstract
Dopamine (DA) is critical for motivation, reward, movement initiation, and learning. Mechanisms that control DA signaling have a profound impact on these important behaviors, and additionally play a role in DA-related neuropathologies. The presynaptic SLC6 DA transporter (DAT) limits extracellular DA levels by clearing released DA, and is potently inhibited by addictive and therapeutic psychostimulants. Decades of evidence support that the DAT is subject to acute regulation by a number of signaling pathways, and that endocytic trafficking strongly regulates DAT availability and function. DAT trafficking studies have been performed in a variety of model systems, including both in vitro and ex vivo preparations. In this review, we focus on the breadth of DAT trafficking studies, with specific attention to, and comparison of, how context may influence DAT's response to different stimuli. In particular, this overview highlights that stimulated DAT trafficking not only differs between in vitro and ex vivo environments, but also is influenced by both sex and anatomical subregions.
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Affiliation(s)
- Rita R Fagan
- Brudnick Neuropsychiatric Research Institute, Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA, 01605, USA
| | - Patrick J Kearney
- Brudnick Neuropsychiatric Research Institute, Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA, 01605, USA
| | - Haley E Melikian
- Brudnick Neuropsychiatric Research Institute, Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA, 01605, USA.
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Amphetamine Stimulates Endocytosis of the Norepinephrine and Neuronal Glutamate Transporters in Cultured Locus Coeruleus Neurons. Neurochem Res 2020; 45:1410-1419. [PMID: 31912366 PMCID: PMC7260265 DOI: 10.1007/s11064-019-02939-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 12/16/2019] [Accepted: 12/18/2019] [Indexed: 12/12/2022]
Abstract
Amphetamines and amphetamine-derivatives elevate neurotransmitter concentrations by competing with endogenous biogenic amines for reuptake. In addition, AMPHs have been shown to activate endocytosis of the dopamine transporter (DAT) which further elevates extracellular dopamine (DA). We previously found that the biochemical cascade leading to this cellular process involves entry of AMPH into the cell through the DAT, stimulation of an intracellular trace amine-associated receptor, TAAR1, and activation of the small GTPase, RhoA. We also showed that the neuronal glutamate transporter, EAAT3, undergoes endocytosis via the same cascade in DA neurons, leading to potentiation of glutamatergic inputs. Since AMPH is a transported inhibitor of both DAT and the norepinephrine transporter (NET), and EAAT3 is also expressed in norepinephrine (NE) neurons, we explored the possibility that this signaling cascade occurs in NE neurons. We found that AMPH can cause endocytosis of NET as well as EAAT3 in NE neurons. NET endocytosis is dependent on TAAR1, RhoA, intracellular calcium and CaMKII activation, similar to DAT. However, EAAT3 endocytosis is similar in all regards except its dependence upon CaMKII activation. RhoA activation is dependent on calcium, but not CaMKII, explaining a divergence in AMPH-mediated endocytosis of DAT and NET from that of EAAT3. These data indicate that AMPHs and other TAAR1 agonists can affect glutamate signaling through internalization of EAAT3 in NE as well as DA neurons.
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16
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Thal LB, Tomlinson ID, Quinlan MA, Kovtun O, Blakely RD, Rosenthal SJ. Single Quantum Dot Imaging Reveals PKCβ-Dependent Alterations in Membrane Diffusion and Clustering of an Attention-Deficit Hyperactivity Disorder/Autism/Bipolar Disorder-Associated Dopamine Transporter Variant. ACS Chem Neurosci 2019; 10:460-471. [PMID: 30153408 PMCID: PMC6411462 DOI: 10.1021/acschemneuro.8b00350] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The dopamine transporter (DAT) is a transmembrane protein that terminates dopamine signaling in the brain by driving rapid dopamine reuptake into presynaptic nerve terminals. Several lines of evidence indicate that DAT dysfunction is linked to neuropsychiatric disorders such as attention-deficit/hyperactivity disorder (ADHD), bipolar disorder (BPD), and autism spectrum disorder (ASD). Indeed, individuals with these disorders have been found to express the rare, functional DAT coding variant Val559, which confers anomalous dopamine efflux (ADE) in vitro and in vivo. To elucidate the impact of the DAT Val559 variant on membrane diffusion dynamics, we implemented our antagonist-conjugated quantum dot (QD) labeling approach to monitor the lateral mobility of single particle-labeled transporters in transfected HEK-293 and SK-N-MC cells. Our results demonstrate significantly higher diffusion coefficients of DAT Val559 compared to those of DAT Ala559, effects likely determined by elevated N-terminal transporter phosphorylation. We also provide pharmacological evidence that PKCβ-mediated signaling supports enhanced DAT Val559 membrane diffusion rates. Additionally, our results are complimented with diffusion rates of phosphomimicked and phosphorylation-occluded DAT variants. Furthermore, we show DAT Val559 has a lower propensity for membrane clustering, which may be caused by a mutation-derived shift out of membrane microdomains leading to faster lateral membrane diffusion rates. These findings further demonstrate a functional impact of DAT Val559 and suggest that changes in transporter localization and lateral mobility may sustain ADE and contribute to alterations in dopamine signaling underlying multiple neuropsychiatric disorders.
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17
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Lohani S, Martig AK, Underhill SM, DeFrancesco A, Roberts MJ, Rinaman L, Amara S, Moghaddam B. Burst activation of dopamine neurons produces prolonged post-burst availability of actively released dopamine. Neuropsychopharmacology 2018; 43:2083-2092. [PMID: 29795245 PMCID: PMC6098082 DOI: 10.1038/s41386-018-0088-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2017] [Revised: 04/26/2018] [Accepted: 04/29/2018] [Indexed: 12/26/2022]
Abstract
Both phasic and tonic modes of neurotransmission are implicated in critical functions assigned to dopamine. In learning, for example, sub-second phasic responses of ventral tegmental area (VTA) dopamine neurons to salient events serve as teaching signals, but learning is also interrupted by dopamine antagonists administered minutes after training. Our findings bridge the multiple timescales of dopamine neurotransmission by demonstrating that burst stimulation of VTA dopamine neurons produces a prolonged post-burst increase (>20 min) of extracellular dopamine in nucleus accumbens and prefrontal cortex. This elevation is not due to spillover from the stimulation surge but depends on impulse flow-mediated dopamine release. We identified Rho-mediated internalization of dopamine transporter as a mechanism responsible for prolonged availability of actively released dopamine. Thus, a critical consequence of burst activity of dopamine neurons may be post-burst sustained elevation of extracellular dopamine in terminal regions via an intracellular mechanism that promotes dopamine transporter internalization. These results demonstrate that phasic and tonic dopamine neurotransmission can be a continuum and may explain why both modes of signaling are critical for motivational and cognitive functions associated with dopamine.
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Affiliation(s)
- Sweyta Lohani
- 0000 0004 1936 9000grid.21925.3dDepartment of Neuroscience, University of Pittsburgh, Pittsburgh, PA 15260 USA
| | - Adria K. Martig
- 0000 0004 1936 9000grid.21925.3dDepartment of Neuroscience, University of Pittsburgh, Pittsburgh, PA 15260 USA ,0000 0004 0444 3589grid.281219.1Present Address: The New York Academy of Sciences, New York, NY USA
| | - Suzanne M. Underhill
- 0000 0004 1936 9000grid.21925.3dDepartment of Neurobiology, University of Pittsburgh, Pittsburgh, PA 15260 USA ,0000 0004 0464 0574grid.416868.5Present Address: National Institute of Mental Health, Bethesda, MD USA
| | - Alicia DeFrancesco
- 0000 0004 1936 9000grid.21925.3dDepartment of Neuroscience, University of Pittsburgh, Pittsburgh, PA 15260 USA ,0000 0001 2164 3847grid.67105.35Present Address: Case Western Reserve University, Cleveland, OH USA
| | - Melanie J. Roberts
- 0000 0004 1936 9000grid.21925.3dDepartment of Neuroscience, University of Pittsburgh, Pittsburgh, PA 15260 USA
| | - Linda Rinaman
- 0000 0004 1936 9000grid.21925.3dDepartment of Neuroscience, University of Pittsburgh, Pittsburgh, PA 15260 USA ,0000 0004 0472 0419grid.255986.5Present Address: Department of Psychology, Florida State University, Tallahassee, FL USA
| | - Susan Amara
- 0000 0004 1936 9000grid.21925.3dDepartment of Neurobiology, University of Pittsburgh, Pittsburgh, PA 15260 USA ,0000 0004 0464 0574grid.416868.5Present Address: National Institute of Mental Health, Bethesda, MD USA
| | - Bita Moghaddam
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA, 15260, USA. .,Department of Behavioral Neuroscience, Oregon Health and Science University, Portland, OR, 97239, USA.
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Underhill SM, Ingram SL, Ahmari SE, Veenstra-VanderWeele J, Amara SG. Neuronal excitatory amino acid transporter EAAT3: Emerging functions in health and disease. Neurochem Int 2018; 123:69-76. [PMID: 29800605 DOI: 10.1016/j.neuint.2018.05.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Revised: 05/18/2018] [Accepted: 05/21/2018] [Indexed: 01/09/2023]
Affiliation(s)
- Suzanne M Underhill
- National Institutes of Health, National Institute of Mental Health, 35 Convent Drive, Bethesda, MD 20892, USA.
| | - Susan L Ingram
- Department of Neurological Surgery, Oregon Health & Science University (OHSU), 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA
| | - Susanne E Ahmari
- Department of Psychiatry, University of Pittsburgh, 450 Technology Drive, Room 227, Pittsburgh, PA 15219, USA
| | - Jeremy Veenstra-VanderWeele
- Department of Psychiatry, Columbia University, New York State Psychiatric Institute, 1051 Riverside Drive, Mail Unit 78, New York, NY, 10032, USA
| | - Susan G Amara
- National Institutes of Health, National Institute of Mental Health, 35 Convent Drive, Bethesda, MD 20892, USA
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19
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Cinque S, Zoratto F, Poleggi A, Leo D, Cerniglia L, Cimino S, Tambelli R, Alleva E, Gainetdinov RR, Laviola G, Adriani W. Behavioral Phenotyping of Dopamine Transporter Knockout Rats: Compulsive Traits, Motor Stereotypies, and Anhedonia. Front Psychiatry 2018; 9:43. [PMID: 29520239 PMCID: PMC5826953 DOI: 10.3389/fpsyt.2018.00043] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Accepted: 01/31/2018] [Indexed: 12/30/2022] Open
Abstract
Alterations in dopamine neurotransmission are generally associated with diseases such as attention-deficit/hyperactivity disorder (ADHD) and obsessive-compulsive disorder (OCD). Such diseases typically feature poor decision making and lack of control on executive functions and have been studied through the years using many animal models. Dopamine transporter (DAT) knockout (KO) and heterozygous (HET) mice, in particular, have been widely used to study ADHD. Recently, a strain of DAT KO rats has been developed (1). Here, we provide a phenotypic characterization of reward sensitivity and compulsive choice by adult rats born from DAT-HET dams bred with DAT-HET males, in order to further validate DAT KO rats as an animal model for preclinical research. We first tested DAT KO rats' sensitivity to rewarding stimuli, provided by highly appetitive food or sweet water; then, we tested their choice behavior with an Intolerance-to-Delay Task (IDT). During these tests, DAT KO rats appeared less sensitive to rewarding stimuli than wild-type (WT) and HET rats: they also showed a prominent hyperactive behavior with a rigid choice pattern and a wide number of compulsive stereotypies. Moreover, during the IDT, we tested the effects of amphetamine (AMPH) and RO-5203648, a trace amine-associated receptor 1 (TAAR1) partial agonist. AMPH accentuated impulsive behaviors in WT and HET rats, while it had no effect in DAT KO rats. Finally, we measured the levels of tyrosine hydroxylase, dopamine receptor 2 (D2), serotonin transporter, and TAAR1 mRNA transcripts in samples of ventral striatum, finding no significant differences between WT and KO genotypes. Throughout this study, DAT KO rats showed alterations in decision-making processes and in motivational states, as well as prominent motor and oral stereotypies: more studies are warranted to fully characterize and efficiently use them in preclinical research.
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Affiliation(s)
- Stefano Cinque
- Center for Behavioral Sciences and Mental Health, Istituto Superiore di Sanità, Rome, Italy
- Department of Neuroscience, Istituto Superiore di Sanità, Rome, Italy
| | - Francesca Zoratto
- Center for Behavioral Sciences and Mental Health, Istituto Superiore di Sanità, Rome, Italy
| | - Anna Poleggi
- Department of Neuroscience, Istituto Superiore di Sanità, Rome, Italy
| | - Damiana Leo
- Neuroscience and Brain Technologies Department, Fondazione Istituto Italiano di Tecnologia, Genoa, Italy
| | - Luca Cerniglia
- Faculty of Psychology, International Telematic University Uninettuno, Rome, Italy
| | - Silvia Cimino
- Department of Dynamic and Clinical Psychology, Sapienza University of Rome, Rome, Italy
| | - Renata Tambelli
- Department of Dynamic and Clinical Psychology, Sapienza University of Rome, Rome, Italy
| | - Enrico Alleva
- Center for Behavioral Sciences and Mental Health, Istituto Superiore di Sanità, Rome, Italy
| | - Raul R. Gainetdinov
- Skolkovo Institute of Science and Technology, Moscow, Russia
- Institute of Translational Biomedicine, St. Petersburg State University, St. Petersburg, Russia
| | - Giovanni Laviola
- Center for Behavioral Sciences and Mental Health, Istituto Superiore di Sanità, Rome, Italy
| | - Walter Adriani
- Center for Behavioral Sciences and Mental Health, Istituto Superiore di Sanità, Rome, Italy
- Faculty of Psychology, International Telematic University Uninettuno, Rome, Italy
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20
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Pronounced Hyperactivity, Cognitive Dysfunctions, and BDNF Dysregulation in Dopamine Transporter Knock-out Rats. J Neurosci 2018; 38:1959-1972. [PMID: 29348190 DOI: 10.1523/jneurosci.1931-17.2018] [Citation(s) in RCA: 114] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Revised: 01/07/2018] [Accepted: 01/11/2018] [Indexed: 12/16/2022] Open
Abstract
Dopamine (DA) controls many vital physiological functions and is critically involved in several neuropsychiatric disorders such as schizophrenia and attention deficit hyperactivity disorder. The major function of the plasma membrane dopamine transporter (DAT) is the rapid uptake of released DA into presynaptic nerve terminals leading to control of both the extracellular levels of DA and the intracellular stores of DA. Here, we present a newly developed strain of rats in which the gene encoding DAT knockout Rats (DAT-KO) has been disrupted by using zinc finger nuclease technology. Male and female DAT-KO rats develop normally but weigh less than heterozygote and wild-type rats and demonstrate pronounced spontaneous locomotor hyperactivity. While striatal extracellular DA lifetime and concentrations are significantly increased, the total tissue content of DA is markedly decreased demonstrating the key role of DAT in the control of DA neurotransmission. Hyperactivity of DAT-KO rats can be counteracted by amphetamine, methylphenidate, the partial Trace Amine-Associated Receptor 1 (TAAR1) agonist RO5203648 ((S)-4-(3,4-Dichloro-phenyl)-4,5-dihydro-oxazol-2-ylamine) and haloperidol. DAT-KO rats also demonstrate a deficit in working memory and sensorimotor gating tests, less propensity to develop obsessive behaviors and show strong dysregulation in frontostriatal BDNF function. DAT-KO rats could provide a novel translational model for human diseases involving aberrant DA function and/or mutations affecting DAT or related regulatory mechanisms.SIGNIFICANCE STATEMENT Here, we present a newly developed strain of rats in which the gene encoding the dopamine transporter (DAT) has been disrupted (Dopamine Transporter Knockout rats [DAT-KO rats]). DAT-KO rats display functional hyperdopaminergia accompanied by pronounced spontaneous locomotor hyperactivity. Hyperactivity of DAT-KO rats can be counteracted by amphetamine, methylphenidate, and a few other compounds exerting inhibitory action on dopamine-dependent hyperactivity. DAT-KO rats also demonstrate cognitive deficits in working memory and sensorimotor gating tests, less propensity to develop compulsive behaviors, and strong dysregulation in frontostriatal BDNF function. These observations highlight the key role of DAT in the control of brain dopaminergic transmission. DAT-KO rats could provide a novel translational model for human diseases involving aberrant dopamine functions.
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21
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Gaskill PJ, Miller DR, Gamble-George J, Yano H, Khoshbouei H. HIV, Tat and dopamine transmission. Neurobiol Dis 2017; 105:51-73. [PMID: 28457951 PMCID: PMC5541386 DOI: 10.1016/j.nbd.2017.04.015] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Revised: 04/04/2017] [Accepted: 04/16/2017] [Indexed: 01/02/2023] Open
Abstract
Human Immunodeficiency Virus (HIV) is a progressive infection that targets the immune system, affecting more than 37 million people around the world. While combinatorial antiretroviral therapy (cART) has lowered mortality rates and improved quality of life in infected individuals, the prevalence of HIV associated neurocognitive disorders is increasing and HIV associated cognitive decline remains prevalent. Recent research has suggested that HIV accessory proteins may be involved in this decline, and several studies have indicated that the HIV protein transactivator of transcription (Tat) can disrupt normal neuronal and glial function. Specifically, data indicate that Tat may directly impact dopaminergic neurotransmission, by modulating the function of the dopamine transporter and specifically damaging dopamine-rich regions of the CNS. HIV infection of the CNS has long been associated with dopaminergic dysfunction, but the mechanisms remain undefined. The specific effect(s) of Tat on dopaminergic neurotransmission may be, at least partially, a mechanism by which HIV infection directly or indirectly induces dopaminergic dysfunction. Therefore, precisely defining the specific effects of Tat on the dopaminergic system will help to elucidate the mechanisms by which HIV infection of the CNS induces neuropsychiatric, neurocognitive and neurological disorders that involve dopaminergic neurotransmission. Further, this will provide a discussion of the experiments needed to further these investigations, and may help to identify or develop new therapeutic approaches for the prevention or treatment of these disorders in HIV-infected individuals.
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Affiliation(s)
- Peter J Gaskill
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, United States.
| | - Douglas R Miller
- Department of Neuroscience, University of Florida, Gainesville, FL 32611, United States
| | - Joyonna Gamble-George
- Department of Neuroscience, University of Florida, Gainesville, FL 32611, United States
| | - Hideaki Yano
- National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, United States
| | - Habibeh Khoshbouei
- Department of Neuroscience, University of Florida, Gainesville, FL 32611, United States.
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22
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Wang P, Zhang X, Fu T, Li S, Li B, Xue W, Yao X, Chen Y, Zhu F. Differentiating Physicochemical Properties between Addictive and Nonaddictive ADHD Drugs Revealed by Molecular Dynamics Simulation Studies. ACS Chem Neurosci 2017; 8:1416-1428. [PMID: 28557437 DOI: 10.1021/acschemneuro.7b00173] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Attention-deficit/hyperactivity disorder (ADHD) is the most commonly diagnosed mental disorder of children and adolescents. Although psychostimulants are currently the first-line drugs for ADHD, their highly addictive profile raises great abuse concerns. It is known that psychostimulants' addictiveness is largely attributed to their interaction with dopamine transporter (DAT) and their binding modes in DAT can thus facilitate the understanding of the mechanism underlining drugs' addictiveness. However, no DAT residue able to discriminate ADHD drugs' addictiveness is identified, and the way how different drug structures affect their abuse liability is still elusive. In this study, multiple computational methods were integrated to differentiate binding modes between approved psychostimulants and ADHD drugs of little addictiveness. As a result, variation in energy contribution of 8 residues between addictive and nonaddictive drugs was observed, and a reduction in hydrophobicity of drugs' 2 functional groups was identified as the indicator of drugs' addictiveness. This finding agreed well with the physicochemical properties of 8 officially reported controlled substances. The identified variations in binding mode can shed light on the mechanism underlining drugs' addictiveness, which may thus facilitate the discovery of improved ADHD therapeutics with reduced addictive profile.
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Affiliation(s)
- Panpan Wang
- College of Pharmaceutical
Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
- Innovative Drug Research and Bioinformatics
Group, School of Pharmaceutical Sciences and Collaborative Innovation
Center for Brain Science, Chongqing University, Chongqing 401331, China
| | - Xiaoyu Zhang
- Innovative Drug Research and Bioinformatics
Group, School of Pharmaceutical Sciences and Collaborative Innovation
Center for Brain Science, Chongqing University, Chongqing 401331, China
| | - Tingting Fu
- Innovative Drug Research and Bioinformatics
Group, School of Pharmaceutical Sciences and Collaborative Innovation
Center for Brain Science, Chongqing University, Chongqing 401331, China
| | - Shuang Li
- Innovative Drug Research and Bioinformatics
Group, School of Pharmaceutical Sciences and Collaborative Innovation
Center for Brain Science, Chongqing University, Chongqing 401331, China
| | - Bo Li
- Innovative Drug Research and Bioinformatics
Group, School of Pharmaceutical Sciences and Collaborative Innovation
Center for Brain Science, Chongqing University, Chongqing 401331, China
| | - Weiwei Xue
- Innovative Drug Research and Bioinformatics
Group, School of Pharmaceutical Sciences and Collaborative Innovation
Center for Brain Science, Chongqing University, Chongqing 401331, China
| | - Xiaojun Yao
- State Key Laboratory of Applied Organic
Chemistry and Department of Chemistry, Lanzhou University, Lanzhou 730000, China
| | - Yuzong Chen
- Bioinformatics and
Drug Design Group, Department of Pharmacy, National University of Singapore, Singapore 117543, Singapore
| | - Feng Zhu
- College of Pharmaceutical
Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
- Innovative Drug Research and Bioinformatics
Group, School of Pharmaceutical Sciences and Collaborative Innovation
Center for Brain Science, Chongqing University, Chongqing 401331, China
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23
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Li MH, Underhill SM, Reed C, Phillips TJ, Amara SG, Ingram SL. Amphetamine and Methamphetamine Increase NMDAR-GluN2B Synaptic Currents in Midbrain Dopamine Neurons. Neuropsychopharmacology 2017; 42:1539-1547. [PMID: 27976681 PMCID: PMC5436114 DOI: 10.1038/npp.2016.278] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 11/29/2016] [Accepted: 12/11/2016] [Indexed: 02/07/2023]
Abstract
The psychostimulants amphetamine (AMPH) and methamphetamine (MA) are widely abused illicit drugs. Here we show that both psychostimulants acutely increase NMDA receptor (NMDAR)-mediated synaptic currents and decrease AMPA receptor (AMPAR)/NMDAR ratios in midbrain dopamine neurons. The potentiation depends on the transport of AMPH into the cell by the dopamine transporter. NMDAR-GluN2B receptor inhibitors, ifenprodil, RO 25-6981, and RO 04-5595, inhibit the potentiation without affecting basal-evoked NMDA currents, indicating that NMDAR-GluN2B receptors are activated by AMPH. A selective peptide inhibitor of AMPH-dependent trafficking of the neuronal excitatory amino acid transporter 3 (EAAT3) blocks potentiation, suggesting that EAAT3 internalization increases extracellular glutamate concentrations and activates GluN2B-containing NMDARs. Experiments with the use-dependent NMDAR blocker, MK-801, indicate that potentiated NMDARs reside on the plasma membrane and are not inserted de novo. In behavioral studies, GluN2B inhibitors reduce MA-mediated locomotor activity, without affecting basal activity. These results reveal an important interaction between dopamine and glutamatergic signaling in midbrain dopamine neurons in response to acute administration of psychostimulants.
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Affiliation(s)
- Ming-Hua Li
- Department of Neurological Surgery, Oregon Health & Science University, Portland, OR, USA
| | - Suzanne M Underhill
- National Institute of Mental Health, National Institutes of Health, Laboratory of Molecular and Cellular Neurobiology, Bethesda, MD, USA
| | - Cheryl Reed
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR, USA
| | - Tamara J Phillips
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR, USA,VA Portland Health Care System, Portland, OR, USA
| | - Susan G Amara
- National Institute of Mental Health, National Institutes of Health, Laboratory of Molecular and Cellular Neurobiology, Bethesda, MD, USA
| | - Susan L Ingram
- Department of Neurological Surgery, Oregon Health & Science University, Portland, OR, USA,Department of Neurological Surgery, Oregon Health & Science University (OHSU), 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA, Tel: 503 494 1220, Fax: 503 494 2664, E-mail:
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24
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Harun R, Hare KM, Brough EM, Munoz MJ, Grassi CM, Torres GE, Grace AA, Wagner AK. Fast-scan cyclic voltammetry demonstrates that L-DOPA produces dose-dependent, regionally selective bimodal effects on striatal dopamine kinetics in vivo. J Neurochem 2016; 136:1270-1283. [PMID: 26611352 PMCID: PMC4884169 DOI: 10.1111/jnc.13444] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 11/17/2015] [Accepted: 11/18/2015] [Indexed: 11/29/2022]
Abstract
Parkinson's disease (PD) is a debilitating condition that is caused by a relatively specific degeneration of dopaminergic (DAergic) neurons of the substantia nigra pars compacta. L-DOPA was introduced as a viable treatment option for PD over 40 years ago and still remains the most common and effective therapy for PD. Though the effects of L-DOPA to augment striatal DA production are well known, little is actually known about how L-DOPA alters the kinetics of DA neurotransmission that contribute to its beneficial and adverse effects. In this study, we examined the effects of L-DOPA administration (50 mg/kg carbidopa + 0, 100, and 250 mg/kg L-DOPA) on regional electrically stimulated DA response kinetics using fast-scan cyclic voltammetry in anesthetized rats. We demonstrate that L-DOPA enhances DA release in both the dorsal striatum (D-STR) and nucleus accumbens (NAc), but surprisingly causes a delayed inhibition of release in the D-STR. In both regions, L-DOPA progressively attenuated reuptake kinetics, predominantly through a decrease in Vmax . These findings have important implications on understanding the pharmacodynamics of L-DOPA, which may be informative for understanding its therapeutic effects and also common side effects like L-DOPA-induced dyskinesias (LID). L-DOPA is commonly used to treat Parkinsonian symptoms, but little is known about how it affects presynaptic DA neurotransmission. Using in vivo fast-scan cyclic voltammetry, we show L-DOPA inhibits DA reuptake in a region-specific and dose-dependent manner, and L-DOPA has paradoxical effects on release. These findings may be important when considering mechanisms for L-DOPA's therapeutic benefits and adverse side-effects.
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Affiliation(s)
- Rashed Harun
- Center for Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
- Department of Physical Medicine & Rehabilitation, University of Pittsburgh, School of Medicine, Pittsburgh, Pennsylvania, USA
- Safar Center for Resuscitation Research, Pittsburgh, Pennsylvania, USA
| | - Kristin M Hare
- Department of Physical Medicine & Rehabilitation, University of Pittsburgh, School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Elizabeth M Brough
- Department of Physical Medicine & Rehabilitation, University of Pittsburgh, School of Medicine, Pittsburgh, Pennsylvania, USA
- Safar Center for Resuscitation Research, Pittsburgh, Pennsylvania, USA
| | - Miranda J Munoz
- Department of Physical Medicine & Rehabilitation, University of Pittsburgh, School of Medicine, Pittsburgh, Pennsylvania, USA
- Department of Biological Sciences, Carnegie Mellon University, Mellon College of Science, Pittsburgh, Pennsylvania, USA
| | - Christine M Grassi
- Department of Physical Medicine & Rehabilitation, University of Pittsburgh, School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Gonzalo E Torres
- Center for Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
- Department of Neurobiology, University of Pittsburgh, School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Anthony A Grace
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
- Departments of Psychiatry and Psychology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Amy K Wagner
- Center for Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
- Department of Physical Medicine & Rehabilitation, University of Pittsburgh, School of Medicine, Pittsburgh, Pennsylvania, USA
- Safar Center for Resuscitation Research, Pittsburgh, Pennsylvania, USA
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
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Membrane potential shapes regulation of dopamine transporter trafficking at the plasma membrane. Nat Commun 2016; 7:10423. [PMID: 26804245 PMCID: PMC4737753 DOI: 10.1038/ncomms10423] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Accepted: 12/09/2015] [Indexed: 12/17/2022] Open
Abstract
The dopaminergic system is essential for cognitive processes, including reward, attention and motor control. In addition to DA release and availability of synaptic DA receptors, timing and magnitude of DA neurotransmission depend on extracellular DA-level regulation by the dopamine transporter (DAT), the membrane expression and trafficking of which are highly dynamic. Data presented here from real-time TIRF (TIRFM) and confocal microscopy coupled with surface biotinylation and electrophysiology suggest that changes in the membrane potential alone, a universal yet dynamic cellular property, rapidly alter trafficking of DAT to and from the surface membrane. Broadly, these findings suggest that cell-surface DAT levels are sensitive to membrane potential changes, which can rapidly drive DAT internalization from and insertion into the cell membrane, thus having an impact on the capacity for DAT to regulate extracellular DA levels. The dopaminergic system has important roles in a number of cognitive process. Here, the authors use detailed analysis of dopamine transporter trafficking to show its levels at the cell surface are sensitive to changes in membrane potential.
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26
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Insights in how amphetamine ROCKs (Rho-associated containing kinase) membrane protein trafficking. Proc Natl Acad Sci U S A 2015; 112:15538-9. [PMID: 26607447 DOI: 10.1073/pnas.1520960112] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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27
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Amphetamine activates Rho GTPase signaling to mediate dopamine transporter internalization and acute behavioral effects of amphetamine. Proc Natl Acad Sci U S A 2015; 112:E7138-47. [PMID: 26553986 DOI: 10.1073/pnas.1511670112] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Acute amphetamine (AMPH) exposure elevates extracellular dopamine through a variety of mechanisms that include inhibition of dopamine reuptake, depletion of vesicular stores, and facilitation of dopamine efflux across the plasma membrane. Recent work has shown that the DAT substrate AMPH, unlike cocaine and other nontransported blockers, can also stimulate endocytosis of the plasma membrane dopamine transporter (DAT). Here, we show that when AMPH enters the cytoplasm it rapidly stimulates DAT internalization through a dynamin-dependent, clathrin-independent process. This effect, which can be observed in transfected cells, cultured dopamine neurons, and midbrain slices, is mediated by activation of the small GTPase RhoA. Inhibition of RhoA activity with C3 exotoxin or a dominant-negative RhoA blocks AMPH-induced DAT internalization. These actions depend on AMPH entry into the cell and are blocked by the DAT inhibitor cocaine. AMPH also stimulates cAMP accumulation and PKA-dependent inactivation of RhoA, thus providing a mechanism whereby PKA- and RhoA-dependent signaling pathways can interact to regulate the timing and robustness of AMPH's effects on DAT internalization. Consistent with this model, the activation of D1/D5 receptors that couple to PKA in dopamine neurons antagonizes RhoA activation, DAT internalization, and hyperlocomotion observed in mice after AMPH treatment. These observations support the existence of an unanticipated intracellular target that mediates the effects of AMPH on RhoA and cAMP signaling and suggest new pathways to target to disrupt AMPH action.
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Butler B, Saha K, Rana T, Becker JP, Sambo D, Davari P, Goodwin JS, Khoshbouei H. Dopamine Transporter Activity Is Modulated by α-Synuclein. J Biol Chem 2015; 290:29542-54. [PMID: 26442590 DOI: 10.1074/jbc.m115.691592] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Indexed: 12/24/2022] Open
Abstract
The duration and strength of the dopaminergic signal are regulated by the dopamine transporter (DAT). Drug addiction and neurodegenerative and neuropsychiatric diseases have all been associated with altered DAT activity. The membrane localization and the activity of DAT are regulated by a number of intracellular proteins. α-Synuclein, a protein partner of DAT, is implicated in neurodegenerative disease and drug addiction. Little is known about the regulatory mechanisms of the interaction between DAT and α-synuclein, the cellular location of this interaction, and the functional consequences of this interaction on the basal, amphetamine-induced DAT-mediated dopamine efflux, and membrane microdomain distribution of the transporter. Here, we found that the majority of DAT·α-synuclein protein complexes are found at the plasma membrane of dopaminergic neurons or mammalian cells and that the amphetamine-mediated increase in DAT activity enhances the association of these proteins at the plasma membrane. Further examination of the interaction of DAT and α-synuclein revealed a transient interaction between these two proteins at the plasma membrane. Additionally, we found DAT-induced membrane depolarization enhances plasma membrane localization of α-synuclein, which in turn increases dopamine efflux and enhances DAT localization in cholesterol-rich membrane microdomains.
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Affiliation(s)
- Brittany Butler
- From the Departments of Neuroscience and Psychiatry University of Florida, Gainesville, Florida 32611 and
| | - Kaustuv Saha
- From the Departments of Neuroscience and Psychiatry University of Florida, Gainesville, Florida 32611 and
| | - Tanu Rana
- the Department of Biochemistry and Cancer Biology, Meharry Medical College, Nashville, Tennessee 37208
| | - Jonas P Becker
- From the Departments of Neuroscience and Psychiatry University of Florida, Gainesville, Florida 32611 and
| | - Danielle Sambo
- From the Departments of Neuroscience and Psychiatry University of Florida, Gainesville, Florida 32611 and
| | - Paran Davari
- From the Departments of Neuroscience and Psychiatry University of Florida, Gainesville, Florida 32611 and
| | - J Shawn Goodwin
- the Department of Biochemistry and Cancer Biology, Meharry Medical College, Nashville, Tennessee 37208
| | - Habibeh Khoshbouei
- From the Departments of Neuroscience and Psychiatry University of Florida, Gainesville, Florida 32611 and
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29
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Parameyong A, Govitrapong P, Chetsawang B. Melatonin attenuates the mitochondrial translocation of mitochondrial fission proteins and Bax, cytosolic calcium overload and cell death in methamphetamine-induced toxicity in neuroblastoma SH-SY5Y cells. Mitochondrion 2015; 24:1-8. [PMID: 26176977 DOI: 10.1016/j.mito.2015.07.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2015] [Revised: 06/09/2015] [Accepted: 07/09/2015] [Indexed: 12/22/2022]
Abstract
Methamphetamine (METH) is an addictive drug that can cause toxicity and degeneration in the brain. Several pieces of evidence have demonstrated that METH toxicity results in increases in oxidative stress that regulate an intracellular signaling cascade that leads to cell death. Recently, several studies have emphasized that the overload of cytosolic calcium levels and mitochondrial fission into a small mitochondrial structure is involved in cell death processes. In the present study, we aimed to investigate the effects of METH toxicity on cytosolic calcium overload and mitochondrial fission in neuroblastoma SH-SY5Y cells. Additionally, the protective effect of melatonin against METH-induced toxicity was also investigated. The results of the present study demonstrated that METH significantly decreases cell viability and increases the levels of mitochondrial fission (Fis1 and Drp1) proteins and pro-apoptotic protein, Bax in isolated mitochondria. The levels of Drp1 in the cytosol of METH-treated cells had no significant differences compared to the control untreated cells. METH also significantly increased the cytosolic calcium levels. Melatonin reversed the toxic effects of METH by restoring cell viability and inhibiting the increase in mitochondrial Fis1 levels and the mitochondrial translocation of Drp1 and Bax. Additionally, melatonin was able to reduce the METH-induced increase in cytosolic calcium levels and fragmented mitochondria into small globular structures in SH-SY5Y cells. The results of the present study demonstrate the potential abilities of melatonin to maintain the homeostasis of mitochondrial dynamics and cytosolic calcium levels in METH-induced toxicity in neuronal cells.
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Affiliation(s)
- Arisa Parameyong
- Research Center for Neuroscience, Institute of Molecular Biosciences, Mahidol University, Salaya, Nakhon Pathom, Thailand
| | - Piyarat Govitrapong
- Research Center for Neuroscience, Institute of Molecular Biosciences, Mahidol University, Salaya, Nakhon Pathom, Thailand; Center for Neuroscience and Department of Pharmacology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Banthit Chetsawang
- Research Center for Neuroscience, Institute of Molecular Biosciences, Mahidol University, Salaya, Nakhon Pathom, Thailand.
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30
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Hamilton PJ, Shekar A, Belovich AN, Christianson NB, Campbell NG, Sutcliffe JS, Galli A, Matthies HJ, Erreger K. Zn(2+) reverses functional deficits in a de novo dopamine transporter variant associated with autism spectrum disorder. Mol Autism 2015; 6:8. [PMID: 25741436 PMCID: PMC4349303 DOI: 10.1186/s13229-015-0002-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Accepted: 01/27/2015] [Indexed: 12/01/2022] Open
Abstract
Our laboratory recently characterized a novel autism spectrum disorder (ASD)-associated de novo missense mutation in the human dopamine transporter (hDAT) gene SLC6A3 (hDAT T356M). This hDAT variant exhibits dysfunctional forward and reverse transport properties that may contribute to DA dysfunction in ASD. Here, we report that Zn2+ reverses, at least in part, the functional deficits of ASD-associated hDAT variant T356M. These data suggest that the molecular mechanism targeted by Zn2+ to restore partial function in hDAT T356M may be a novel therapeutic target to rescue functional deficits in hDAT variants associated with ASD.
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Affiliation(s)
- Peter J Hamilton
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Room 7124 MRB III, 465 21st Avenue S, Nashville, TN 37232 USA.,Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, Tennessee USA
| | - Aparna Shekar
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Room 7124 MRB III, 465 21st Avenue S, Nashville, TN 37232 USA.,Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee USA
| | - Andrea N Belovich
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Room 7124 MRB III, 465 21st Avenue S, Nashville, TN 37232 USA.,Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee USA
| | - Nicole Bibus Christianson
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Room 7124 MRB III, 465 21st Avenue S, Nashville, TN 37232 USA.,Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, Tennessee USA
| | - Nicholas G Campbell
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Room 7124 MRB III, 465 21st Avenue S, Nashville, TN 37232 USA.,Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, Tennessee USA
| | - James S Sutcliffe
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Room 7124 MRB III, 465 21st Avenue S, Nashville, TN 37232 USA.,Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, Tennessee USA
| | - Aurelio Galli
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Room 7124 MRB III, 465 21st Avenue S, Nashville, TN 37232 USA.,Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, Tennessee USA
| | - Heinrich Jg Matthies
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Room 7124 MRB III, 465 21st Avenue S, Nashville, TN 37232 USA.,Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, Tennessee USA
| | - Kevin Erreger
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Room 7124 MRB III, 465 21st Avenue S, Nashville, TN 37232 USA.,Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, Tennessee USA
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31
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Bowton E, Saunders C, Reddy IA, Campbell NG, Hamilton PJ, Henry LK, Coon H, Sakrikar D, Veenstra-VanderWeele JM, Blakely RD, Sutcliffe J, Matthies HJG, Erreger K, Galli A. SLC6A3 coding variant Ala559Val found in two autism probands alters dopamine transporter function and trafficking. Transl Psychiatry 2014; 4:e464. [PMID: 25313507 PMCID: PMC4350523 DOI: 10.1038/tp.2014.90] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Revised: 08/11/2014] [Accepted: 08/12/2014] [Indexed: 12/12/2022] Open
Abstract
Emerging evidence associates dysfunction in the dopamine (DA) transporter (DAT) with the pathophysiology of autism spectrum disorder (ASD). The human DAT (hDAT; SLC6A3) rare variant with an Ala to Val substitution at amino acid 559 (hDAT A559V) was previously reported in individuals with bipolar disorder or attention-deficit hyperactivity disorder (ADHD). We have demonstrated that this variant is hyper-phosphorylated at the amino (N)-terminal serine (Ser) residues and promotes an anomalous DA efflux phenotype. Here, we report the novel identification of hDAT A559V in two unrelated ASD subjects and provide the first mechanistic description of its impaired trafficking phenotype. DAT surface expression is dynamically regulated by DAT substrates including the psychostimulant amphetamine (AMPH), which causes hDAT trafficking away from the plasma membrane. The integrity of DAT trafficking directly impacts DA transport capacity and therefore dopaminergic neurotransmission. Here, we show that hDAT A559V is resistant to AMPH-induced cell surface redistribution. This unique trafficking phenotype is conferred by altered protein kinase C β (PKCβ) activity. Cells expressing hDAT A559V exhibit constitutively elevated PKCβ activity, inhibition of which restores the AMPH-induced hDAT A559V membrane redistribution. Mechanistically, we link the inability of hDAT A559V to traffic in response to AMPH to the phosphorylation of the five most distal DAT N-terminal Ser. Mutation of these N-terminal Ser to Ala restores AMPH-induced trafficking. Furthermore, hDAT A559V has a diminished ability to transport AMPH, and therefore lacks AMPH-induced DA efflux. Pharmacological inhibition of PKCβ or Ser to Ala substitution in the hDAT A559V background restores AMPH-induced DA efflux while promoting intracellular AMPH accumulation. Although hDAT A559V is a rare variant, it has been found in multiple probands with neuropsychiatric disorders associated with imbalances in DA neurotransmission, including ADHD, bipolar disorder, and now ASD. These findings provide valuable insight into a new cellular phenotype (altered hDAT trafficking) supporting dysregulated DA function in these disorders. They also provide a novel potential target (PKCβ) for therapeutic interventions in individuals with ASD.
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Affiliation(s)
- E Bowton
- Departments of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN, USA,Vanderbilt Brain Institute, Vanderbilt University Medical Center, Nashville, TN, USA
| | - C Saunders
- Vanderbilt Brain Institute, Vanderbilt University Medical Center, Nashville, TN, USA,Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - I A Reddy
- Departments of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN, USA,Vanderbilt Brain Institute, Vanderbilt University Medical Center, Nashville, TN, USA
| | - N G Campbell
- Departments of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN, USA,Vanderbilt Brain Institute, Vanderbilt University Medical Center, Nashville, TN, USA
| | - P J Hamilton
- Departments of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN, USA,Vanderbilt Brain Institute, Vanderbilt University Medical Center, Nashville, TN, USA
| | - L K Henry
- Department of Basic Sciences, University of North Dakota, Grand Forks, ND, USA
| | - H Coon
- Department of Psychiatry, University of Utah, Salt Lake City, UT, USA
| | - D Sakrikar
- Vanderbilt Brain Institute, Vanderbilt University Medical Center, Nashville, TN, USA,Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - J M Veenstra-VanderWeele
- Vanderbilt Brain Institute, Vanderbilt University Medical Center, Nashville, TN, USA,Department of Psychiatry, Vanderbilt University Medical Center, Nashville, TN, USA
| | - R D Blakely
- Vanderbilt Brain Institute, Vanderbilt University Medical Center, Nashville, TN, USA,Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - J Sutcliffe
- Departments of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN, USA,Vanderbilt Brain Institute, Vanderbilt University Medical Center, Nashville, TN, USA,Department of Psychiatry, Vanderbilt University Medical Center, Nashville, TN, USA
| | - H J G Matthies
- Departments of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN, USA,Vanderbilt Brain Institute, Vanderbilt University Medical Center, Nashville, TN, USA,N-PISA Neuroscience Program In Substance Abuse, Vanderbilt University Medical Center, Nashville, TN, USA,Departments of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, 465 21st Avenue South, MRB3, Room 7124, Nashville, TN 37232, USA E-mail: or
| | - K Erreger
- Departments of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN, USA,Vanderbilt Brain Institute, Vanderbilt University Medical Center, Nashville, TN, USA,N-PISA Neuroscience Program In Substance Abuse, Vanderbilt University Medical Center, Nashville, TN, USA,Departments of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, 465 21st Avenue South, MRB3, Room 7124, Nashville, TN 37232, USA E-mail: or
| | - A Galli
- Departments of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN, USA,Vanderbilt Brain Institute, Vanderbilt University Medical Center, Nashville, TN, USA,N-PISA Neuroscience Program In Substance Abuse, Vanderbilt University Medical Center, Nashville, TN, USA,Departments of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, 465 21st Avenue South, MRB3, Room 7130A, Nashville, TN 37232, USA. E-mail:
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32
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Underhill SM, Wheeler DS, Li M, Watts SD, Ingram SL, Amara SG. Amphetamine modulates excitatory neurotransmission through endocytosis of the glutamate transporter EAAT3 in dopamine neurons. Neuron 2014; 83:404-416. [PMID: 25033183 DOI: 10.1016/j.neuron.2014.05.043] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/27/2014] [Indexed: 12/15/2022]
Abstract
Amphetamines modify the brain and alter behavior through mechanisms generally attributed to their ability to regulate extracellular dopamine concentrations. However, the actions of amphetamine are also linked to adaptations in glutamatergic signaling. We report here that when amphetamine enters dopamine neurons through the dopamine transporter, it stimulates endocytosis of an excitatory amino acid transporter, EAAT3, in dopamine neurons. Consistent with this decrease in surface EAAT3, amphetamine potentiates excitatory synaptic responses in dopamine neurons. We also show that the process of internalization is dynamin- and Rho-mediated and requires a unique sequence in the cytosolic C terminus of EAAT3. Introduction of a peptide based on this motif into dopamine neurons blocks the effects of amphetamine on EAAT3 internalization and its action on excitatory responses. These data indicate that the internalization of EAAT3 triggered by amphetamine increases glutamatergic signaling and thus contributes to the effects of amphetamine on neurotransmission.
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Affiliation(s)
- Suzanne M Underhill
- Laboratory of Molecular and Cellular Neurobiology, NIH/NIMH, Bethesda, MD 20892, USA.
| | - David S Wheeler
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Minghua Li
- Department of Neurological Surgery, Oregon Health and Science University, Portland, OR 97239, USA
| | - Spencer D Watts
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Susan L Ingram
- Department of Neurological Surgery, Oregon Health and Science University, Portland, OR 97239, USA
| | - Susan G Amara
- Laboratory of Molecular and Cellular Neurobiology, NIH/NIMH, Bethesda, MD 20892, USA; Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA 15260, USA
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33
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Arias-Carrión O, Caraza-Santiago X, Salgado-Licona S, Salama M, Machado S, Nardi AE, Menéndez-González M, Murillo-Rodríguez E. Orquestic regulation of neurotransmitters on reward-seeking behavior. Int Arch Med 2014; 7:29. [PMID: 25061480 PMCID: PMC4108978 DOI: 10.1186/1755-7682-7-29] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Accepted: 05/31/2014] [Indexed: 01/15/2023] Open
Abstract
The ventral tegmental area is strongly associated with the reward system. Dopamine is released in areas such as the nucleus accumbens and prefrontal cortex as a result of rewarding experiences such as food, sex, and neutral stimuli that become associated with them. Electrical stimulation of the ventral tegmental area or its output pathways can itself serve as a potent reward. Different drugs that increase dopamine levels are intrinsically rewarding. Although the dopaminergic system represent the cornerstone of the reward system, other neurotransmitters such as endogenous opioids, glutamate, γ-Aminobutyric acid, acetylcholine, serotonin, adenosine, endocannabinoids, orexins, galanin and histamine all affect this mesolimbic dopaminergic system. Consequently, genetic variations of neurotransmission are thought influence reward processing that in turn may affect distinctive social behavior and susceptibility to addiction. Here, we discuss current evidence on the orquestic regulation of different neurotranmitters on reward-seeking behavior and its potential effect on drug addiction.
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Affiliation(s)
- Oscar Arias-Carrión
- Unidad de Trastornos del Movimiento y Sueño (TMS), Hospital General Dr. Manuel Gea González, Mexico City, Mexico ; Unidad de Trastornos del Movimiento y Sueño (TMS), Hospital General Ajusco Medio, Mexico City, Mexico
| | - Xanic Caraza-Santiago
- Unidad de Trastornos del Movimiento y Sueño (TMS), Hospital General Dr. Manuel Gea González, Mexico City, Mexico
| | - Sergio Salgado-Licona
- Unidad de Trastornos del Movimiento y Sueño (TMS), Hospital General Dr. Manuel Gea González, Mexico City, Mexico
| | - Mohamed Salama
- Toxicology Department and Medical Experimental Research Center (MERC), Faculty of Medicine, Mansoura University, Mansoura, Egypt
| | - Sergio Machado
- Panic and Respiration, Institute of Psychiatry of Federal University of Rio de Janeiro, Rio de Janeiro, Brazil ; Physical Activity Neuroscience Physical Activity Sciences Postgraduate Program, Salgado de Oliveira University, Niterói, Brazil
| | - Antonio Egidio Nardi
- Panic and Respiration, Institute of Psychiatry of Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | | | - Eric Murillo-Rodríguez
- Laboratorio de Neurociencias Moleculares e Integrativas, Escuela de Medicina, División Ciencias de la Salud, Universidad Anáhuac Mayab, Mérida, Yucatán, Mexico
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34
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Jørgensen TN, Christensen PM, Gether U. Serotonin-induced down-regulation of cell surface serotonin transporter. Neurochem Int 2014; 73:107-12. [PMID: 24462583 DOI: 10.1016/j.neuint.2014.01.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Revised: 01/06/2014] [Accepted: 01/09/2014] [Indexed: 01/15/2023]
Abstract
The serotonin transporter (SERT) terminates serotonergic signaling and enables refilling of synaptic vesicles by mediating reuptake of serotonin (5-HT) released into the synaptic cleft. The molecular and cellular mechanisms controlling SERT activity and surface expression are not fully understood. Here we demonstrate that the substrate 5-HT itself causes acute down-regulation of SERT cell surface expression. To assess surface SERT expression by ELISA, we used a SERT variant (TacSERT) where the N-terminus of SERT was fused to the intracellular tail of the extracellularly FLAG-tagged single-membrane spanning protein Tac. In stably transfected HEK293 cells, 5-HT caused a dose-dependent reduction in TacSERT surface signal with an EC50 value equivalent to the Km value observed for 5-HT uptake. The 5-HT-induced reduction in surface signal reached maximum within 40-60min and was blocked by the selective SERT inhibitor S-citalopram. 5-HT-induced reduction in SERT expression was further supported by surface biotinylation experiments showing 5-HT-induced reduction in wild type SERT plasma membrane levels. Moreover, preincubation with 5-HT lowered the Vmax for 5-HT uptake in cultured raphe serotonergic neurons, indicting that endogenous cell-surface resident SERT likewise is down-regulated in the presence of substrate.
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Affiliation(s)
- Trine Nygaard Jørgensen
- Molecular Neuropharmacology Laboratory, Department of Neuroscience and Pharmacology, The Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Peter Møller Christensen
- Molecular Neuropharmacology Laboratory, Department of Neuroscience and Pharmacology, The Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Ulrik Gether
- Molecular Neuropharmacology Laboratory, Department of Neuroscience and Pharmacology, The Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark.
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35
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The effect of manganese on dopamine toxicity and dopamine transporter (DAT) in control and DAT transfected HEK cells. Neurotoxicology 2013; 35:121-8. [PMID: 23313730 DOI: 10.1016/j.neuro.2013.01.002] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Revised: 01/02/2013] [Accepted: 01/04/2013] [Indexed: 11/23/2022]
Abstract
Chronic exposure to Mn results in the development of a neurological disorder known as manganism characterized by neurological deficits resembling that seen in Parkinsonism. Although dopaminergic neurons within the nigrostriatal pathway appear intact, Mn-induced irregularities in DA transmission have been observed including decreased amphetamine-induced DA release and loss of the dopamine transporter (DAT). Results of studies to evaluate the effect of Mn and DA on cell viability in control and DAT-transfected HEK cells reveal that Mn is equally toxic to both cell lines whereas DA was only toxic to cells containing DAT. DA toxicity was saturable suggesting that transport may be rate limiting. When Mn and DA were added simultaneously to the media, cell toxicity was similar to that produced by Mn alone suggesting that Mn may suppress DA uptake in the DAT containing cells. Preincubation of DA prior to the addition of Mn resulted in cell death which was essentially additive with that produced independently by the two agents. Mn was also shown to decrease DA uptake and amphetamine-induced DA efflux in DAT containing cells. Time-lapsed confocal microscopy indicates that Mn can promote trafficking of cell surface DAT into intracellular compartments which may account for the decrease in DA uptake and DA efflux in these cells. Mn-induced internalization of DAT may provide an explanation for disruption in DA transmission previously reported in the striatum.
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36
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Attention deficit/hyperactivity disorder-derived coding variation in the dopamine transporter disrupts microdomain targeting and trafficking regulation. J Neurosci 2012; 32:5385-97. [PMID: 22514303 DOI: 10.1523/jneurosci.6033-11.2012] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Attention deficit/hyperactivity disorder (ADHD) is the most commonly diagnosed disorder of school-age children. Although genetic and brain-imaging studies suggest a contribution of altered dopamine (DA) signaling in ADHD, evidence of signaling perturbations contributing to risk is largely circumstantial. The presynaptic, cocaine- and amphetamine (AMPH)-sensitive DA transporter (DAT) constrains DA availability at presynaptic and postsynaptic receptors following vesicular release and is targeted by the most commonly prescribed ADHD therapeutics. Using polymorphism discovery approaches with an ADHD cohort, we identified a hDAT (human DAT) coding variant, R615C, located in the distal C terminus of the transporter, a region previously implicated in constitutive and regulated transporter trafficking. Here, we demonstrate that, whereas wild-type DAT proteins traffic in a highly regulated manner, DAT 615C proteins recycle constitutively and demonstrate insensitivity to the endocytic effects of AMPH and PKC (protein kinase C) activation. The disrupted regulation of DAT 615C parallels a redistribution of the transporter variant away from GM1 ganglioside- and flotillin1-enriched membranes, and is accompanied by altered CaMKII (calcium/calmodulin-dependent protein kinase II) and flotillin-1 interactions. Using C-terminal peptides derived from wild-type DAT and the R615C variant, we establish that the DAT 615C C terminus can act dominantly to preclude AMPH regulation of wild-type DAT. Mutagenesis of DAT C-terminal sequences suggests that phosphorylation of T613 may be important in sorting DAT between constitutive and regulated pathways. Together, our studies support a coupling of DAT microdomain localization with transporter regulation and provide evidence of perturbed DAT activity and DA signaling as a risk determinant for ADHD.
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37
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Kristensen AS, Andersen J, Jørgensen TN, Sørensen L, Eriksen J, Loland CJ, Strømgaard K, Gether U. SLC6 neurotransmitter transporters: structure, function, and regulation. Pharmacol Rev 2011; 63:585-640. [PMID: 21752877 DOI: 10.1124/pr.108.000869] [Citation(s) in RCA: 591] [Impact Index Per Article: 45.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The neurotransmitter transporters (NTTs) belonging to the solute carrier 6 (SLC6) gene family (also referred to as the neurotransmitter-sodium-symporter family or Na(+)/Cl(-)-dependent transporters) comprise a group of nine sodium- and chloride-dependent plasma membrane transporters for the monoamine neurotransmitters serotonin (5-hydroxytryptamine), dopamine, and norepinephrine, and the amino acid neurotransmitters GABA and glycine. The SLC6 NTTs are widely expressed in the mammalian brain and play an essential role in regulating neurotransmitter signaling and homeostasis by mediating uptake of released neurotransmitters from the extracellular space into neurons and glial cells. The transporters are targets for a wide range of therapeutic drugs used in treatment of psychiatric diseases, including major depression, anxiety disorders, attention deficit hyperactivity disorder and epilepsy. Furthermore, psychostimulants such as cocaine and amphetamines have the SLC6 NTTs as primary targets. Beginning with the determination of a high-resolution structure of a prokaryotic homolog of the mammalian SLC6 transporters in 2005, the understanding of the molecular structure, function, and pharmacology of these proteins has advanced rapidly. Furthermore, intensive efforts have been directed toward understanding the molecular and cellular mechanisms involved in regulation of the activity of this important class of transporters, leading to new methodological developments and important insights. This review provides an update of these advances and their implications for the current understanding of the SLC6 NTTs.
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Affiliation(s)
- Anders S Kristensen
- Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences, University of Copenhagen, Copenhagen, Denmark.
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38
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Abstract
Spontaneous and/or stimulated neural activity of the nigrostriatal dopamine (DA) pathway makes amines run out from the neurons. This DA dynamic follows a rather complex path, running in or out the terminals, and flushing or diffusing into the extracellular space. The location of this leakage is not limited to the axon terminals; it also occurs from the cell bodies and dendrites. This molecular release mechanism was, for a long time, considered as being produced, in part, by the exocytosis of previously stored vesicles. The DA carrier protein (DAT, DA transporter) embedded in the DA cell membrane is known to clear previously released amines through an inward DA influx. The DAT also appears to be an active vector of amine release. Particular local conditions and the presence of numerous psychostimulant substances are able to trigger an outward efflux of DA through the DAT. This process, delivering slowly large amounts of amine could play a major regulatory role in extracellular DA homeostasis.
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Affiliation(s)
- Vincent Leviel
- INSERM U846, Stem Cell and Brain Research Institute, Bron, France.
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Is slow-onset long-acting monoamine transport blockade to cocaine as methadone is to heroin? Implication for anti-addiction medications. Neuropsychopharmacology 2010; 35:2564-78. [PMID: 20827272 PMCID: PMC2978747 DOI: 10.1038/npp.2010.133] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The success of methadone in treating opiate addiction has suggested that long-acting agonist therapies may be similarly useful for treating cocaine addiction. Here, we examined this hypothesis, using the slow-onset long-acting monoamine reuptake inhibitor 31,345, a trans-aminotetralin analog, in a variety of addiction-related animal models, and compared it with methadone's effects on heroin's actions in the same animal models. Systemic administration of 31,345 produced long-lasting enhancement of electrical brain-stimulation reward (BSR) and extracellular nucleus accumbens (NAc) dopamine (DA). Pretreatment with 31,345 augmented cocaine-enhanced BSR, prolonged cocaine-enhanced NAc DA, and produced a long-term (24-48 h) reduction in cocaine self-administration rate without obvious extinction pattern, suggesting an additive effect of 31,345 with cocaine. In contrast, methadone pretreatment not only dose-dependently inhibited heroin self-administration with an extinction pattern but also dose-dependently inhibited heroin-enhanced BSR and NAc DA, suggesting functional antagonism by methadone of heroin's actions. In addition, 31,345 appears to possess significant abuse liability, as it produces dose-dependent enhancement of BSR and NAc DA, maintains a low rate of self-administration behavior, and dose-dependently reinstates drug-seeking behavior. In contrast, methadone only partially maintains self-administration with an extinction pattern, and fails to induce reinstatement of drug-seeking behavior. These findings suggest that 31,345 is a cocaine-like slow-onset long-acting monoamine transporter inhibitor that may act as an agonist therapy for cocaine addiction. However, its pattern of action appears to be significantly different from that of methadone. Ideal agonist substitutes for cocaine should fully emulate methadone's actions, that is, functionally antagonizing cocaine's action while blocking monoamine transporters to augment synaptic DA.
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Arias-Carrión O, Stamelou M, Murillo-Rodríguez E, Menéndez-González M, Pöppel E. Dopaminergic reward system: a short integrative review. Int Arch Med 2010; 3:24. [PMID: 20925949 PMCID: PMC2958859 DOI: 10.1186/1755-7682-3-24] [Citation(s) in RCA: 214] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2010] [Accepted: 10/06/2010] [Indexed: 11/18/2022] Open
Abstract
Memory is an essential element to adaptive behavior since it allows consolidation of past experience guiding the subject to consider them in future experiences. Among the endogenous molecules that participate in the consolidation of memory, including the drug-seeking reward, considered as a form of learning, is dopamine. This neurotransmitter modulates the activity of specific brain nucleus such as nuclei accumbens, putamen, ventral tegmental area (VTA), among others and synchronizes the activity of these nuclei to establish the neurobiological mechanism to set the hedonic element of learning. We review the experimental evidence that highlights the activity of different brain nuclei modulating the mechanisms whereby dopamine biases memory towards events that are of motivational significance.
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Affiliation(s)
- Oscar Arias-Carrión
- Human Science Center (FESTO-Program for Applied Knowing), Ludwig-Maximilians-Universität, Munich, Germany.
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41
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Arias-Carrión O, Stamelou M, Murillo-Rodríguez E, Menéndez-González M, Pöppel E. Dopaminergic reward system: a short integrative review. Int Arch Med 2010. [PMID: 20925949 DOI: 10.1186/1755-7682-3-24.] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Memory is an essential element to adaptive behavior since it allows consolidation of past experience guiding the subject to consider them in future experiences. Among the endogenous molecules that participate in the consolidation of memory, including the drug-seeking reward, considered as a form of learning, is dopamine. This neurotransmitter modulates the activity of specific brain nucleus such as nuclei accumbens, putamen, ventral tegmental area (VTA), among others and synchronizes the activity of these nuclei to establish the neurobiological mechanism to set the hedonic element of learning. We review the experimental evidence that highlights the activity of different brain nuclei modulating the mechanisms whereby dopamine biases memory towards events that are of motivational significance.
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Affiliation(s)
- Oscar Arias-Carrión
- Human Science Center (FESTO-Program for Applied Knowing), Ludwig-Maximilians-Universität, Munich, Germany.
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42
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Eriksen J, Bjørn-Yoshimoto WE, Jørgensen TN, Newman AH, Gether U. Postendocytic sorting of constitutively internalized dopamine transporter in cell lines and dopaminergic neurons. J Biol Chem 2010; 285:27289-27301. [PMID: 20551317 DOI: 10.1074/jbc.m110.131003] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The dopamine transporter (DAT) mediates reuptake of released dopamine and is the target for psychostimulants, such as cocaine and amphetamine. DAT undergoes marked constitutive endocytosis, but little is known about the fate and sorting of the endocytosed transporter. To study DAT sorting in cells lines, we fused the one-transmembrane segment protein Tac to DAT, thereby generating a transporter (TacDAT) with an extracellular antibody epitope suited for trafficking studies. TacDAT was functional and endocytosed constitutively in HEK293 cells. According to an ELISA-based assay, TacDAT intracellular accumulation was increased by the lysosomal protease inhibitor leupeptin and by monensin, an inhibitor of lysosomal degradation and recycling. Monensin also reduced TacDAT surface expression consistent with partial recycling. In both HEK293 cells and in the dopaminergic cell line 1Rb3An27, constitutively internalized TacDAT displayed primary co-localization with the late endosomal marker Rab7, less co-localization with the "short loop" recycling marker Rab4, and little co-localization with the marker of "long loop" recycling endosomes, Rab11. Removal by mutation of N-terminal ubiquitination sites did not affect this sorting pattern. The sorting pattern was distinct from a bona fide recycling membrane protein, the beta(2)-adrenergic receptor, that co-localized primarily with Rab11 and Rab4. Constitutively internalized wild type DAT probed with the fluorescently tagged cocaine analogue JHC 1-64, exhibited the same co-localization pattern as TacDAT in 1Rb3An27 cells and in cultured midbrain dopaminergic neurons. We conclude that DAT is constitutively internalized and sorted in a ubiquitination-independent manner to late endosomes/lysosomes and in part to a Rab4 positive short loop recycling pathway.
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Affiliation(s)
- Jacob Eriksen
- Molecular Neuropharmacology Group and Center for Pharmacogenomics, Department of Neuroscience and Pharmacology, Faculty of Health Sciences, Panum Institute, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Walden Emil Bjørn-Yoshimoto
- Molecular Neuropharmacology Group and Center for Pharmacogenomics, Department of Neuroscience and Pharmacology, Faculty of Health Sciences, Panum Institute, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Trine Nygaard Jørgensen
- Molecular Neuropharmacology Group and Center for Pharmacogenomics, Department of Neuroscience and Pharmacology, Faculty of Health Sciences, Panum Institute, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Amy Hauck Newman
- Medicinal Chemistry Section, Intramural Research Program, National Institute on Drug Abuse, Baltimore, Maryland 21224
| | - Ulrik Gether
- Molecular Neuropharmacology Group and Center for Pharmacogenomics, Department of Neuroscience and Pharmacology, Faculty of Health Sciences, Panum Institute, University of Copenhagen, DK-2200 Copenhagen, Denmark.
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43
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Methner DNR, Mayfield RD. Ethanol alters endosomal recycling of human dopamine transporters. J Biol Chem 2010; 285:10310-7. [PMID: 20133946 DOI: 10.1074/jbc.m109.029561] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Dynamic membrane trafficking of the monoamine dopamine transporter (DAT) regulates dopaminergic signaling. Various intrinsic and pharmacological modulators can alter this trafficking. Previously we have shown ethanol potentiates in vitro DAT function and increases surface expression. However, the mechanism underlying these changes is unclear. In the present study, we found ethanol directly regulates DAT function by altering endosomal recycling of the transporter. We defined ethanol action on transporter regulation by [(3)H]DA uptake functional analysis combined with biochemical and immunological assays in stably expressing DAT HEK-293 cells. Short-term ethanol exposure potentiated DAT function in a concentration-, but not time-dependent manner. This potentiation was accompanied by a parallel increase in DAT surface expression. Ethanol had no effect on function or surface localization of the ethanol-insensitive mutant (G130T DAT), suggesting a trafficking-dependent mechanism in mediating the ethanol sensitivity of the transporter. The ethanol-induced increase in DAT surface expression occurred without altering the overall size of DAT endosomal recycling pools. We found ethanol increased the DAT membrane insertion rate while having no effect on internalization of the transporter. Ethanol had no effect on the surface expression or trafficking of the endogenously expressing transferrin receptor, suggesting ethanol does not have a nonspecific effect on endosomal recycling. These results define a novel trafficking mechanism by which ethanol regulates DAT function.
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Affiliation(s)
- D Nicole Riherd Methner
- Waggoner Center for Alcohol and Addiction Research, University of Texas, Austin, Texas 78712, USA
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44
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Chen R, Furman CA, Gnegy ME. Dopamine transporter trafficking: rapid response on demand. FUTURE NEUROLOGY 2010; 5:123. [PMID: 20174452 DOI: 10.2217/fnl.09.76] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The dopamine transporter (DAT) is a primary determinant of the concentration of dopamine in the synapse and is involved in a number of psychiatric and neurological diseases. The transporter actively takes up its physiological substrate, dopamine, when it is on the surface of the plasmalemmal membrane, but the concentration of DAT in the membrane is highly regulated by substrate. Substrates initially, and very rapidly, recruit more DAT into the membrane for greater function, but continued presence of substrate downregulates the activity of DAT and even membrane DAT content. This biphasic regulation is orchestrated by numerous signal transduction mechanisms, including a palette of protein kinases. Understanding the mechanisms of rapid regulation of DAT could provide new therapeutic strategies to improve transporter function and modulate responses to its more notorious substrates, amphetamine and methamphetamine.
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Affiliation(s)
- Rong Chen
- Department of Pharmacology, University of Michigan School of Medicine, Ann Arbor, MI 48109-5632, USA Tel.: +1 734 763 3083
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45
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Robertson SD, Matthies HJG, Galli A. A closer look at amphetamine-induced reverse transport and trafficking of the dopamine and norepinephrine transporters. Mol Neurobiol 2009; 39:73-80. [PMID: 19199083 PMCID: PMC2729543 DOI: 10.1007/s12035-009-8053-4] [Citation(s) in RCA: 138] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2008] [Accepted: 01/12/2009] [Indexed: 10/21/2022]
Abstract
Amphetamine (AMPH) and its derivatives are regularly used in the treatment of a wide array of disorders such as attention-deficit hyperactivity disorder (ADHD), obesity, traumatic brain injury, and narcolepsy (Prog Neurobiol 75:406-433, 2005; J Am Med Assoc 105:2051-2054, 1935; J Am Acad Child Adolesc Psychiatry 41:514-521, 2002; Neuron 43:261-269, 2004; Annu Rev Pharmacol Toxicol 47:681-698, 2007; Drugs Aging 21:67-79, 2004). Despite the important medicinal role for AMPH, it is more widely known for its psychostimulant and addictive properties as a drug of abuse. The primary molecular targets of AMPH are both the vesicular monoamine transporters (VMATs) and plasma membrane monoamine-dopamine (DA), norepinephrine (NE), and serotonin (5-HT)-transporters. The rewarding and addicting properties of AMPH rely on its ability to act as a substrate for these transporters and ultimately increase extracellular levels of monoamines. AMPH achieves this elevation in extracellular levels of neurotransmitter by inducing synaptic vesicle depletion, which increases intracellular monoamine levels, and also by promoting reverse transport (efflux) through plasma membrane monoamine transporters (J Biol Chem 237:2311-2317, 1962; Med Exp Int J Exp Med 6:47-53, 1962; Neuron 19:1271-1283, 1997; J Physiol 144:314-336, 1958; J Neurosci 18:1979-1986, 1998; Science 237:1219-1223, 1987; J Neurosc 15:4102-4108, 1995). This review will focus on two important aspects of AMPH-induced regulation of the plasma membrane monoamine transporters-transporter mediated monoamine efflux and transporter trafficking.
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Affiliation(s)
- S D Robertson
- Neuroscience Graduate Program, Vanderbilt University, Nashville, TN, USA
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46
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Zhu J, Reith MEA. Role of the dopamine transporter in the action of psychostimulants, nicotine, and other drugs of abuse. CNS & NEUROLOGICAL DISORDERS-DRUG TARGETS 2009; 7:393-409. [PMID: 19128199 DOI: 10.2174/187152708786927877] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
A number of studies over the last two decades have demonstrated the critical importance of dopamine (DA) in the behavioral pharmacology and addictive properties of abused drugs. The DA transporter (DAT) is a major target for drugs of abuse in the category of psychostimulants, and for methylphenidate (MPH), a drug used for treating attention deficit hyperactivity disorder (ADHD), which can also be a psychostimulant drug of abuse. Other drugs of abuse such as nicotine, ethanol, heroin and morphine interact with the DAT in more indirect ways. Despite the different ways in which drugs of abuse can affect DAT function, one evolving theme in all cases is regulation of the DAT at the level of surface expression. DAT function is dynamically regulated by multiple intracellular and extracellular signaling pathways and several protein-protein interactions. In addition, DAT expression is regulated through the removal (internalization) and recycling of the protein from the cell surface. Furthermore, recent studies have demonstrated that individual differences in response to novel environments and psychostimulants can be predicted based on individual basal functional DAT expression. Although current knowledge of multiple factors regulating DAT activity has greatly expanded, many aspects of this regulation remain to be elucidated; these data will enable efforts to identify drugs that might be used therapeutically for drug dependence therapeutics.
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Affiliation(s)
- J Zhu
- Department of Psychology, University of South Carolina, Columbia, SC 29208, USA.
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47
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Zahniser NR, Sorkin A. Trafficking of dopamine transporters in psychostimulant actions. Semin Cell Dev Biol 2009; 20:411-7. [PMID: 19560046 DOI: 10.1016/j.semcdb.2009.01.004] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2008] [Revised: 01/10/2009] [Accepted: 01/13/2009] [Indexed: 10/21/2022]
Abstract
Brain dopamine (DA) plays a pivotal role in drug addiction. Since the plasma membrane DA transporter (DAT) is critical for terminating DA neurotransmission, it is important to understand how DATs are regulated and this regulation impacts drug addiction. The number of cell surface DATs is controlled by constitutive and regulated endocytic trafficking. Psychostimulants impact this trafficking. Amphetamines, DAT substrates, cause rapid up-regulation and slower down-regulation of DAT whereas cocaine, a DAT inhibitor, increases surface DATs. Recent reports have begun to elucidate the molecular mechanisms of these psychostimulant effects and link changes in DAT trafficking to psychostimulant-induced reward/reinforcement in animal models.
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Affiliation(s)
- Nancy R Zahniser
- Department of Pharmacology, University of Colorado Denver, Aurora, CO 80045, USA.
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48
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Richards TL, Zahniser NR. Rapid substrate-induced down-regulation in function and surface localization of dopamine transporters: rat dorsal striatum versus nucleus accumbens. J Neurochem 2009; 108:1575-84. [PMID: 19183252 DOI: 10.1111/j.1471-4159.2009.05910.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The dopamine transporter (DAT) substrates dopamine, d-amphetamine (AMPH), and methamphetamine are known to rapidly and transiently reduce DAT activity and/or surface expression in dorsal striatum and heterologous expression systems. We sought to determine if similar substrate-induced regulation of DATs occurs in rat nucleus accumbens. In dorsal striatum synaptosomes, brief (15-min) in vitro substrate pre-exposure markedly decreased maximal [(3)H]dopamine uptake velocity whereas identical substrate pre-exposure in nucleus accumbens synaptosomes produced a smaller, non-significant reduction. However, 45 min after systemic AMPH administration, maximal ex vivo [(3)H]dopamine uptake velocity was significantly reduced in both brain regions. Protein kinase C inhibition blocked AMPH's down-regulation of DAT activity. DAT synaptosomal surface expression was not modified following either the brief in vitro or in vivo AMPH pre-exposure but was reduced after a longer (1-h) in vitro pre-exposure in both brain regions. Together, our findings suggest that relatively brief substrate exposure results in greater down-regulation of DAT activity in dorsal striatum than in nucleus accumbens. Moreover, exposure to AMPH appears to regulate striatal DATs in a biphasic manner, with an initial protein kinase C-dependent decrease in DAT-mediated uptake velocity and then, with longer exposure, a reduction in DAT surface expression.
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Affiliation(s)
- Toni L Richards
- School of Medicine, Department of Pharmacology, University of Colorado Denver, Aurora, Colorado, USA.
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49
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Misra SN, Kahlig KM, George AL. Impaired NaV1.2 function and reduced cell surface expression in benign familial neonatal-infantile seizures. Epilepsia 2008; 49:1535-45. [PMID: 18479388 PMCID: PMC3647030 DOI: 10.1111/j.1528-1167.2008.01619.x] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
PURPOSE Mutations in SCN2A, the gene encoding the brain voltage-gated sodium channel alpha-subunit Na(V)1.2, are associated with inherited epilepsies including benign familial neonatal-infantile seizures (BFNIS). Functional characterization of three BFNIS mutations was performed to identify defects in channel function that underlie this disease. METHODS We examined three BFNIS mutations (R1319Q, L1330F, and L1563V) using whole-cell patch-clamp recording of heterologously expressed human Na(V)1.2. Membrane biotinylation was employed to examine the cell surface protein expression of the four Na(V)1.2 alleles. RESULTS R1319Q displayed mixed effects on activation and fast inactivation gating, consistent with a net loss of channel function. L1563V exhibited impaired fast inactivation predicting a net gain of channel function. The L1330F mutation significantly decreased overall channel availability during repetitive stimulation. Patch-clamp analysis also revealed that cells expressing BFNIS mutants exhibited lower levels of sodium current compared to wild type (WT) Na(V)1.2. Biochemical experiments demonstrated that all three BFNIS mutations exhibited a significant reduction in cell surface expression compared to WT. DISCUSSION Our findings indicate that BFNIS is associated with a range of biophysical defects accompanied by reduced levels of channel protein at the plasma membrane.
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Affiliation(s)
| | | | - Alfred L. George
- Department of Pharmacology, Vanderbilt University
- Division of Genetic Medicine, Department of Medicine, Vanderbilt University
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50
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Riherd DN, Galindo DG, Krause LR, Mayfield RD. Ethanol potentiates dopamine uptake and increases cell surface distribution of dopamine transporters expressed in SK-N-SH and HEK-293 cells. Alcohol 2008; 42:499-508. [PMID: 18579334 DOI: 10.1016/j.alcohol.2008.04.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2007] [Revised: 04/29/2008] [Accepted: 04/29/2008] [Indexed: 11/15/2022]
Abstract
Ethanol increases dopaminergic release in the reward and reinforcement areas of the brain. The primary protein responsible for terminating dopamine (DA) neurotransmission is the plasma membrane-bound dopamine transporter (DAT). In vitro electrophysiological and biochemical studies in Xenopus laevis oocytes have previously shown ethanol potentiates DAT function and increases transporter-binding sites. The potentiating effect of ethanol on the transporter is eliminated in Xenopus oocytes by the DAT mutation glycine 130 to threonine. However, ethanol's action on DAT functional regulation has yet to be examined in mammalian cell expression systems. To further understand the molecular mechanisms of ethanol's action on DAT, we determined the direct mechanistic action of short-term (< or =2 h) ethanol exposure on transporter function and cell surface distribution in non-neuronal human embryonic kidney cells-293 (HEK-293) and neuronal SK-N-SH neuroblastoma cells expressing the transporter. Wild-type or G130T mutant DAT were overexpressed in HEK-293 and SK-N-SH cells. Ethanol potentiated DAT mediated [(3)H]DA uptake in a dose (25, 50, 100 mM), but not time dependent manner in cells expressing wild-type DAT. Ethanol-induced potentiation of uptake was significantly reduced in cells expressing the G130T mutant. Analysis of DA uptake kinetic parameters indicates 100-mM ethanol exposure increased [(3)H]DA uptake velocity (V(max)), while affinity for DA (K(m)) remained unchanged. The effect of ethanol on wild-type DAT surface expression was measured by biotinylation cell surface labeling. DAT surface expression increased 40%-50% after 1-h, 100-mM ethanol exposure. These studies show ethanol potentiates DAT functional regulation in both neuronal and non-neuronal cells, suggesting a direct mechanistic action of ethanol on transporter trafficking in mammalian systems. Our findings demonstrate ethanol's action on DAT function and regulation is consistent across multiple model systems.
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Affiliation(s)
- D Nicole Riherd
- Waggoner Center for Alcohol and Addiction Research, University of Texas at Austin, Austin, TX 78712, USA
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