1
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Sočan V, Dolinar K, Kržan M. Kinetic Properties and Pharmacological Modulation of High- and Low-Affinity Dopamine Transport in Striatal Astrocytes of Adult Rats. Int J Mol Sci 2024; 25:5135. [PMID: 38791173 PMCID: PMC11121484 DOI: 10.3390/ijms25105135] [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: 04/03/2024] [Revised: 05/06/2024] [Accepted: 05/07/2024] [Indexed: 05/26/2024] Open
Abstract
Astrocytes actively participate in neurotransmitter homeostasis by bidirectional communication with neuronal cells, a concept named the tripartite synapse, yet their role in dopamine (DA) homeostasis remains understudied. In the present study, we investigated the kinetic and molecular mechanisms of DA transport in cultured striatal astrocytes of adult rats. Kinetic uptake experiments were performed using radiolabeled [3H]-DA, whereas mRNA expression of the dopamine, norepinephrine, organic cation and plasma membrane monoamine transporters (DAT, NET, OCTs and PMAT) and DA receptors D1 and D2 was determined by qPCR. Additionally, astrocyte cultures were subjected to a 24 h treatment with the DA receptor agonist apomorphine, the DA receptor antagonist haloperidol and the DA precursor L-DOPA. [3H]-DA uptake exhibited temperature, concentration and sodium dependence, with potent inhibition by desipramine, nortriptyline and decynium-22, suggesting the involvement of multiple transporters. qPCR revealed prominent mRNA expression of the NET, the PMAT and OCT1, alongside lower levels of mRNA for OCT2, OCT3 and the DAT. Notably, apomorphine significantly altered NET, PMAT and D1 mRNA expression, while haloperidol and L-DOPA had a modest impact. Our findings demonstrate that striatal astrocytes aid in DA clearance by multiple transporters, which are influenced by dopaminergic drugs. Our study enhances the understanding of regional DA uptake, paving the way for targeted therapeutic interventions in dopaminergic disorders.
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Affiliation(s)
- Vesna Sočan
- Institute of Pharmacology and Experimental Toxicology, Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia;
| | - Klemen Dolinar
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia;
| | - Mojca Kržan
- Institute of Pharmacology and Experimental Toxicology, Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia;
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2
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Honan LE, Fraser-Spears R, Daws LC. Organic cation transporters in psychiatric and substance use disorders. Pharmacol Ther 2024; 253:108574. [PMID: 38072333 PMCID: PMC11052553 DOI: 10.1016/j.pharmthera.2023.108574] [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: 10/06/2023] [Revised: 11/01/2023] [Accepted: 11/30/2023] [Indexed: 12/23/2023]
Abstract
Psychiatric and substance use disorders inflict major public health burdens worldwide. Their widespread burden is compounded by a dearth of effective treatments, underscoring a dire need to uncover novel therapeutic targets. In this review, we summarize the literature implicating organic cation transporters (OCTs), including three subtypes of OCTs (OCT1, OCT2, and OCT3) and the plasma membrane monoamine transporter (PMAT), in the neurobiology of psychiatric and substance use disorders with an emphasis on mood and anxiety disorders, alcohol use disorder, and psychostimulant use disorder. OCTs transport monoamines with a low affinity but high capacity, situating them to play a central role in regulating monoamine homeostasis. Preclinical evidence discussed here suggests that OCTs may serve as promising targets for treatment of psychiatric and substance use disorders and encourage future research into their therapeutic potential.
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Affiliation(s)
- Lauren E Honan
- The University of Texas Health Science Center at San Antonio, Department of Cellular & Integrative Physiology, USA
| | - Rheaclare Fraser-Spears
- University of the Incarnate Word, Feik School of Pharmacy, Department of Pharmaceutical Sciences, USA
| | - Lynette C Daws
- The University of Texas Health Science Center at San Antonio, Department of Cellular & Integrative Physiology, USA; The University of Texas Health Science Center at San Antonio, Department of Pharmacology, USA.
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3
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Badawy AAB, Guillemin GJ. Species Differences in Tryptophan Metabolism and Disposition. Int J Tryptophan Res 2022; 15:11786469221122511. [PMID: 36325027 PMCID: PMC9620070 DOI: 10.1177/11786469221122511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 07/20/2022] [Indexed: 11/06/2022] Open
Abstract
Major species differences in tryptophan (Trp) metabolism and disposition exist
with important physiological, functional and toxicity implications. Unlike
mammalian and other species in which plasma Trp exists largely bound to albumin,
teleosts and other aquatic species possess little or no albumin, such that Trp
entry into their tissues is not hampered, neither is that of environmental
chemicals and toxins, hence the need for strict measures to safeguard their
aquatic environments. In species sensitive to toxicity of excess Trp, hepatic
Trp 2,3-dioxygenase (TDO) lacks the free apoenzyme and its glucocorticoid
induction mechanism. These species, which are largely herbivorous, however,
dispose of Trp more rapidly and their TDO is activated by smaller doses of Trp
than Trp-tolerant species. In general, sensitive species may possess a higher
indoleamine 2,3-dioxygenase (IDO) activity which equips them to resist immune
insults up to a point. Of the enzymes of the kynurenine pathway beyond TDO and
IDO, 2-amino-3-carboxymuconic acid-6-semialdehyde decarboxylase (ACMSD)
determines the extent of progress of the pathway towards NAD+
synthesis and its activity varies across species, with the domestic cat
(Felis catus) being the leading species possessing the
highest activity, hence its inability to utilise Trp for NAD+
synthesis. The paucity of current knowledge of Trp metabolism and disposition in
wild carnivores, invertebrates and many other animal species described here
underscores the need for further studies of the physiology of these species and
its interaction with Trp metabolism.
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Affiliation(s)
- Abdulla A-B Badawy
- Formerly School of Health Sciences,
Cardiff Metropolitan University, Cardiff, Wales, UK,Abdulla A-B Badawy, Formerly School of
Health Sciences, Cardiff Metropolitan University, Western Avenue, Cardiff,
Wales, CF5 2YB, UK.
| | - Gilles J Guillemin
- Neuroinflammation Group, MND Research
Centre, Macquarie Medical School, Macquarie University, NSW, Australia
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4
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Beaver JN, Weber BL, Ford MT, Anello AE, Kassis SK, Gilman TL. Uncovering Functional Contributions of PMAT ( Slc29a4) to Monoamine Clearance Using Pharmacobehavioral Tools. Cells 2022; 11:cells11121874. [PMID: 35741002 PMCID: PMC9220966 DOI: 10.3390/cells11121874] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 06/01/2022] [Accepted: 06/07/2022] [Indexed: 11/16/2022] Open
Abstract
Plasma membrane monoamine transporter (PMAT, Slc29a4) transports monoamine neurotransmitters, including dopamine and serotonin, faster than more studied monoamine transporters, e.g., dopamine transporter (DAT), or serotonin transporter (SERT), but with ~400–600-fold less affinity. A considerable challenge in understanding PMAT’s monoamine clearance contributions is that no current drugs selectively inhibit PMAT. To advance knowledge about PMAT’s monoamine uptake role, and to circumvent this present challenge, we investigated how drugs that selectively block DAT/SERT influence behavioral readouts in PMAT wildtype, heterozygote, and knockout mice of both sexes. Drugs typically used as antidepressants (escitalopram, bupropion) were administered acutely for readouts in tail suspension and locomotor tests. Drugs with psychostimulant properties (cocaine, D-amphetamine) were administered repeatedly to assess initial locomotor responses plus psychostimulant-induced locomotor sensitization. Though we hypothesized that PMAT-deficient mice would exhibit augmented responses to antidepressant and psychostimulant drugs due to constitutively attenuated monoamine uptake, we instead observed sex-selective responses to antidepressant drugs in opposing directions, and subtle sex-specific reductions in psychostimulant-induced locomotor sensitization. These results suggest that PMAT functions differently across sexes, and support hypotheses that PMAT’s monoamine clearance contribution emerges when frontline transporters (e.g., DAT, SERT) are absent, saturated, and/or blocked. Thus, known human polymorphisms that reduce PMAT function could be worth investigating as contributors to varied antidepressant and psychostimulant responses.
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5
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Shirasaka Y, Seki M, Hatakeyama M, Kurokawa Y, Uchiyama H, Takemura M, Yasugi Y, Kishimoto H, Tamai I, Wang J, Inoue K. Multiple Transport Mechanisms Involved in the Intestinal Absorption of Metformin: Impact on the Nonlinear Absorption Kinetics. J Pharm Sci 2022; 111:1531-1541. [DOI: 10.1016/j.xphs.2022.01.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 01/07/2022] [Accepted: 01/07/2022] [Indexed: 01/11/2023]
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6
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Suzuki S, Inoue K, Tamai I, Shirasaka Y. Model Analysis of the Apparent Saturation Kinetics of Purine Nucleobase Uptake in Cells co-Expressing Transporter and Metabolic Enzyme. Pharm Res 2021; 38:1585-1592. [PMID: 34435306 DOI: 10.1007/s11095-021-03086-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 07/18/2021] [Indexed: 11/24/2022]
Abstract
PURPOSE This study aims to understand the effect of salvage enzyme activity on the saturable kinetics of facilitated cellular uptake of purine nucleobase by developing a cellular kinetic model incorporating equilibrative nucleobase transporter 1 (ENBT1) and adenine phosphoribosyltransferase (APRT), with adenine as a model nucleobase. METHODS A cellular kinetic model incorporating the functions of ENBT1 and APRT was developed using Napp software and employed for model-based analysis of the cellular disposition of adenine. RESULTS Simulation analysis using the developed cellular kinetic model could account for the experimentally observed time-dependent changes in the Km(app) value of adenine for ENBT1-mediated uptake. At a long experimental time, the model shows that uptake of adenine is rate-limited by APRT, enabling determination of the Km value for APRT. At early time, the rate-limiting step for adenine uptake is ENBT1-mediated transport, enabling determination of the Km value for ENBT1. Further simulations showed that the effect of experimental time on the Km(app) value for ENBT1-mediated uptake is dependent on the APRT expression level. CONCLUSION Our findings indicate that both enzyme expression levels and experimental time should be considered when using cellular uptake studies to determine the Km values of purine nucleobases for facilitated transporters.
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Affiliation(s)
- Satoru Suzuki
- Faculty of Pharmacy, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kakuma-machi, Kanazawa, 920-1192, Japan.,School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Tokyo, 192-0392, Japan
| | - Katsuhisa Inoue
- School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Tokyo, 192-0392, Japan
| | - Ikumi Tamai
- Faculty of Pharmacy, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kakuma-machi, Kanazawa, 920-1192, Japan
| | - Yoshiyuki Shirasaka
- Faculty of Pharmacy, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kakuma-machi, Kanazawa, 920-1192, Japan. .,School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Tokyo, 192-0392, Japan.
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7
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Sweet DH. Organic Cation Transporter Expression and Function in the CNS. Handb Exp Pharmacol 2021; 266:41-80. [PMID: 33963461 DOI: 10.1007/164_2021_463] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The blood-brain barrier (BBB) and blood-cerebrospinal fluid barrier (BCSFB) represent major control checkpoints protecting the CNS, by exerting selective control over the movement of organic cations and anions into and out of the CNS compartment. In addition, multiple CNS cell types, e.g., astrocytes, ependymal cells, microglia, contribute to processes that maintain the status quo of the CNS milieu. To fulfill their roles, these barriers and cell types express a multitude of transporter proteins from dozens of different transporter families. Fundamental advances over the past few decades in our knowledge of transporter substrates, expression profiles, and consequences of loss of function are beginning to change basic theories regarding the contribution of various cell types and clearance networks to coordinated neuronal signaling, complex organismal behaviors, and overall CNS homeostasis. In particular, transporters belonging to the Solute Carrier (SLC) superfamily are emerging as major contributors, including the SLC22 organic cation/anion/zwitterion family of transporters (includes OCT1-3 and OCTN1-3), the SLC29 facilitative nucleoside family of transporters (includes PMAT), and the SLC47 multidrug and toxin extrusion family of transporters (includes MATE1-2). These transporters are known to interact with neurotransmitters, antidepressant and anxiolytic agents, and drugs of abuse. Clarifying their contributions to the underlying mechanisms regulating CNS permeation and clearance, as well as the health status of astrocyte, microglial and neuronal cell populations, will drive new levels of understanding as to maintenance of the CNS milieu and approaches to new therapeutics and therapeutic strategies in the treatment of CNS disorders. This chapter highlights organic cation transporters belonging to the SLC superfamily known to be expressed in the CNS, providing an overview of their identification, mechanism of action, CNS expression profile, interaction with neurotransmitters and antidepressant/antipsychotic drugs, and results from behavioral studies conducted in loss of function models (knockout/knockdown).
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Affiliation(s)
- Douglas H Sweet
- Department of Pharmaceutics, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, USA.
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8
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Wei R, Gust SL, Tandio D, Maheux A, Nguyen KH, Wang J, Bourque S, Plane F, Hammond JR. Deletion of murine slc29a4 modifies vascular responses to adenosine and 5-hydroxytryptamine in a sexually dimorphic manner. Physiol Rep 2021; 8:e14395. [PMID: 32170814 PMCID: PMC7070170 DOI: 10.14814/phy2.14395] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 02/18/2020] [Accepted: 02/19/2020] [Indexed: 12/15/2022] Open
Abstract
Equilibrative nucleoside transporter 4 (ENT4), encoded by SLC29A4, mediates the flux of both 5‐hydroxytryptamine (5‐HT) and adenosine across cell membranes. We hypothesized that loss of ENT4 function in mice would modify the effects of these established regulators of vascular function. Male and female wild‐type (WT) and slc29a4‐null (ENT4‐KO) mice were compared with respect to their hemodynamics and mesenteric vascular function. Male ENT4‐KO mice had a complete loss of myogenic tone in their mesenteric resistance arteries. This was accompanied by a decrease in blood flow in the superior mesenteric artery in the male ENT4‐KO mice, and a reduced responsiveness to 5‐HT. In contrast, endothelium‐dependent relaxations of mesenteric arteries from female ENT4‐KO mice were more sensitive to Ca2+‐activated K+ (KCa) channel blockade than WT mice. Female ENT4‐KO mice also demonstrated an enhanced vasodilatory response to adenosine in vivo that was not seen in males. Ketanserin (5‐HT2A inhibitor) and GR55562 (5‐HT1B/1D inhibitor) decreased 5‐HT‐induced tone, but only ketanserin inhibited the relaxant effect of 5‐HT in mesenteric arteries. 5‐HT‐evoked increases in tone were elevated in arteries from ENT4‐KO mice upon block of endothelial relaxant pathways, with arteries from female ENT4‐KO mice showing the greatest increase. Adenosine A2b receptor expression was decreased, while other adenosine transporter subtypes, as well as adenosine deaminase and adenosine kinase were increased in mesenteric arteries from male, but not female, ENT4‐KO mice. These findings indicate that deletion of slc29a4 leads to sex‐specific changes in vascular function with significant consequences for regulation of blood flow and pressure by adenosine and 5‐HT.
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Affiliation(s)
- Ran Wei
- Department of Pharmacology, University of Alberta, Edmonton, AB, Canada
| | - Stephen L Gust
- Department of Pharmacology, University of Alberta, Edmonton, AB, Canada
| | - David Tandio
- Department of Pharmacology, University of Alberta, Edmonton, AB, Canada
| | - Alexia Maheux
- Department of Pharmacology, University of Alberta, Edmonton, AB, Canada
| | - Khanh H Nguyen
- Department of Pharmacology, University of Alberta, Edmonton, AB, Canada
| | - Joanne Wang
- Department of Pharmaceutics, University of Washington, Seattle, WA, USA
| | - Stephane Bourque
- Department of Anaesthesia and Pain Medicine, University of Alberta, Edmonton, AB, Canada
| | - Frances Plane
- Department of Pharmacology, University of Alberta, Edmonton, AB, Canada
| | - James R Hammond
- Department of Pharmacology, University of Alberta, Edmonton, AB, Canada
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9
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Maier J, Niello M, Rudin D, Daws LC, Sitte HH. The Interaction of Organic Cation Transporters 1-3 and PMAT with Psychoactive Substances. Handb Exp Pharmacol 2021; 266:199-214. [PMID: 33993413 DOI: 10.1007/164_2021_469] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Organic cation transporters 1-3 (OCT1-3, SLC22A1-3) and the plasma membrane monoamine transporter (PMAT, SLC29A4) play a major role in maintaining monoaminergic equilibrium in the central nervous system. With many psychoactive substances interacting with OCT1-3 and PMAT, a growing literature focuses on characterizing their properties via in vitro and in vivo studies. In vitro studies mainly aim at characterizing compounds as inhibitors or substrates of murine, rat, and human isoforms. The preponderance of studies has put emphasis on phenylalkylamine derivatives, but ketamine and opioids have also been investigated. Studies employing in vivo (knockout) models mostly concentrate on the interaction of psychoactive substances and OCT3, with an emphasis on stress and addiction, pharmacokinetics, and sensitization to psychoactive drugs. The results highlight the importance of OCT3 in the mechanism of action of psychoactive compounds. Concerning in vivo studies, a veritable research gap concerning OCT1, 2, and PMAT exists. This review provides an overview and summary of research conducted in this field of research.
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Affiliation(s)
- Julian Maier
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Marco Niello
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Deborah Rudin
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Lynette C Daws
- Department of Cellular and Integrative Physiology, University of Texas Health, San Antonio, TX, USA
- Department of Pharmacology, University of Texas Health, San Antonio, TX, USA
| | - Harald H Sitte
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, Vienna, Austria.
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10
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Abstract
Inhibitors of Na+/Cl- dependent high affinity transporters for norepinephrine (NE), serotonin (5-HT), and/or dopamine (DA) represent frequently used drugs for treatment of psychological disorders such as depression, anxiety, obsessive-compulsive disorder, attention deficit hyperactivity disorder, and addiction. These transporters remove NE, 5-HT, and/or DA after neuronal excitation from the interstitial space close to the synapses. Thereby they terminate transmission and modulate neuronal behavioral circuits. Therapeutic failure and undesired central nervous system side effects of these drugs have been partially assigned to neurotransmitter removal by low affinity transport. Cloning and functional characterization of the polyspecific organic cation transporters OCT1 (SLC22A1), OCT2 (SLC22A2), OCT3 (SLC22A3) and the plasma membrane monoamine transporter PMAT (SLC29A4) revealed that every single transporter mediates low affinity uptake of NE, 5-HT, and DA. Whereas the organic transporters are all located in the blood brain barrier, OCT2, OCT3, and PMAT are expressed in neurons or in neurons and astrocytes within brain areas that are involved in behavioral regulation. Areas of expression include the dorsal raphe, medullary motoric nuclei, hypothalamic nuclei, and/or the nucleus accumbens. Current knowledge of the transport of monoamine neurotransmitters by the organic cation transporters, their interactions with psychotropic drugs, and their locations in the brain is reported in detail. In addition, animal experiments including behavior tests in wildtype and knockout animals are reported in which the impact of OCT2, OCT3, and/or PMAT on regulation of salt intake, depression, mood control, locomotion, and/or stress effect on addiction is suggested.
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Affiliation(s)
- Hermann Koepsell
- Institute of Anatomy and Cell Biology, University Würzburg, Würzburg, Germany.
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11
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Abstract
Precise control of monoamine neurotransmitter levels in the central nervous system (CNS) is crucial for proper brain function. Dysfunctional monoamine signaling is associated with several neuropsychiatric and neurodegenerative disorders. The plasma membrane monoamine transporter (PMAT) is a new polyspecific organic cation transporter encoded by the SLC29A4 gene. Capable of transporting monoamine neurotransmitters with low affinity and high capacity, PMAT represents a major uptake2 transporter in the brain. Broadly expressed in multiple brain regions, PMAT can complement the high-affinity, low-capacity monoamine uptake mediated by uptake1 transporters, the serotonin, dopamine, and norepinephrine transporters (SERT, DAT, and NET, respectively). This chapter provides an overview of the molecular and functional characteristics of PMAT together with its regional and cell-type specific expression in the mammalian brain. The physiological functions of PMAT in brain monoamine homeostasis are evaluated in light of its unique transport kinetics and brain location, and in comparison with uptake1 and other uptake2 transporters (e.g., OCT3) along with corroborating experimental evidences. Lastly, the possibility of PMAT's involvement in brain pathophysiological processes, such as autism, depression, and Parkinson's disease, is discussed in the context of disease pathology and potential link to aberrant monoamine pathways.
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12
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Zhu S, Lei S, Zhou S, Jin L, Zeng S, Jiang H, Zhou H. Luteolin shows antidepressant-like effect by inhibiting and downregulating plasma membrane monoamine transporter (PMAT, Slc29a4). J Funct Foods 2019. [DOI: 10.1016/j.jff.2019.01.048] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
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13
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Fraser-Spears R, Krause-Heuer AM, Basiouny M, Mayer FP, Manishimwe R, Wyatt NA, Dobrowolski JC, Roberts MP, Greguric I, Kumar N, Koek W, Sitte HH, Callaghan PD, Fraser BH, Daws LC. Comparative analysis of novel decynium-22 analogs to inhibit transport by the low-affinity, high-capacity monoamine transporters, organic cation transporters 2 and 3, and plasma membrane monoamine transporter. Eur J Pharmacol 2018; 842:351-364. [PMID: 30473490 DOI: 10.1016/j.ejphar.2018.10.028] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Revised: 10/03/2018] [Accepted: 10/19/2018] [Indexed: 11/30/2022]
Abstract
Growing evidence supports involvement of low-affinity/high-capacity organic cation transporters (OCTs) and plasma membrane monoamine transporter (PMAT) in regulating clearance of monoamines. Currently decynium-22 (D22) is the best pharmacological tool to study these transporters, however it does not readily discriminate among them, underscoring a need to develop compounds with greater selectivity for each of these transporters. We developed seven D22 analogs, and previously reported that some have lower affinity for α1-adrenoceptors than D22 and showed antidepressant-like activity in mice. Here, we extend these findings to determine the affinity of these analogs for OCT2, OCT3 and PMAT, as well as serotonin, norepinephrine and dopamine transporters (SERT, NET and DAT) using a combination of uptake competition with [3H]methyl-4-phenylpyridinium acetate in overexpressed HEK cells and [3H]citalopram, [3H]nisoxetine and [3H]WIN 35428 displacement binding in mouse hippocampal and striatal preparations. Like D22, all analogs showed greater binding affinities for OCT3 than OCT2 and PMAT. However, unlike D22, some analogs also showed modest affinity for SERT and DAT. Dual OCT3/SERT and/or OCT3/DAT actions of certain analogs may help explain their ability to produce antidepressant-like effects in mice and help account for our previous findings that D22 lacks antidepressant-like effects unless SERT function is either genetically or pharmacologically compromised. Though these analogs are not superior than D22 in discriminating among OCTs/PMAT, our findings point to development of compounds with combined ability to inhibit both low-affinity/high-capacity transporters, such as OCT3, and high-affinity/low-capacity transporters, such as SERT, as therapeutics with potentially improved efficacy for treatment of psychiatric disorders.
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Affiliation(s)
- Rheaclare Fraser-Spears
- Department of Cellular & Integrative Physiology, University of Texas Health Science Center at San Antonio, United States; University of the Incarnate Word, Feik School of Pharmacy, Department of Pharmaceutical Sciences, United States
| | - Anwen M Krause-Heuer
- The Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia
| | - Mohamed Basiouny
- Department of Cellular & Integrative Physiology, University of Texas Health Science Center at San Antonio, United States
| | - Felix P Mayer
- Medical University of Vienna, Center for Physiology and Pharmacology, Institute of Pharmacology, Währingerstraße 13A, 1090 Vienna, Austria
| | - Retrouvailles Manishimwe
- Department of Cellular & Integrative Physiology, University of Texas Health Science Center at San Antonio, United States
| | - Naomi A Wyatt
- The Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia
| | | | - Maxine P Roberts
- The Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia
| | - Ivan Greguric
- The Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia
| | - Naresh Kumar
- University of New South Wales, School of Chemistry, Sydney, NSW 2052, Australia
| | - Wouter Koek
- Department of Pharmacology, University of Texas Health Science Center at San Antonio, United States; Department of Psychiatry, University of Texas Health Science Center at San Antonio, United States
| | - Harald H Sitte
- Medical University of Vienna, Center for Physiology and Pharmacology, Institute of Pharmacology, Währingerstraße 13A, 1090 Vienna, Austria
| | - Paul D Callaghan
- The Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia
| | - Benjamin H Fraser
- The Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia
| | - Lynette C Daws
- Department of Cellular & Integrative Physiology, University of Texas Health Science Center at San Antonio, United States; Department of Pharmacology, University of Texas Health Science Center at San Antonio, United States.
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14
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Gilman TL, George CM, Vitela M, Herrera-Rosales M, Basiouny MS, Koek W, Daws LC. Constitutive plasma membrane monoamine transporter (PMAT, Slc29a4) deficiency subtly affects anxiety-like and coping behaviours. Eur J Neurosci 2018; 48:10.1111/ejn.13968. [PMID: 29797618 PMCID: PMC6252160 DOI: 10.1111/ejn.13968] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Revised: 05/04/2018] [Accepted: 05/14/2018] [Indexed: 12/27/2022]
Abstract
Originally, uptake-mediated termination of monoamine (e.g., serotonin and dopamine) signalling was believed to only occur via high-affinity, low-capacity transporters ("uptake1 ") such as the serotonin or dopamine transporters, respectively. Now, the important contribution of a second low-affinity, high-capacity class of biogenic amine transporters has been recognised, particularly in circumstances when uptake1 transporter function is reduced (e.g., antidepressant treatment). Pharmacologic or genetic reductions in uptake1 function can change locomotor, anxiety-like or stress-coping behaviours. Comparable behavioural investigations into reduced low-affinity, high-capacity transporter function are lacking, in part, due to a current dearth of drugs that selectively target particular low-affinity, high-capacity transporters, such as the plasma membrane monoamine transporter. Therefore, the most direct approach involves constitutive genetic knockout of these transporters. Other groups have reported that knockout of the low-affinity, high-capacity organic cation transporters 2 or 3 alters anxiety-like and stress-coping behaviours, but none have assessed behaviours in plasma membrane monoamine transporter knockout mice. Here, we evaluated adult male and female plasma membrane monoamine transporter wild-type, heterozygous and knockout mice in locomotor, anxiety-like and stress-coping behavioural tests. A mild enhancement of anxiety-related behaviour was noted in heterozygous mice. Active-coping behaviour was modestly and selectively increased in female knockout mice. These subtle behavioural changes support a supplemental role of plasma membrane monoamine transporter in serotonin and dopamine uptake, and suggest sex differences in transporter function should be examined more closely in future investigations.
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Affiliation(s)
- T. Lee Gilman
- Department of Cellular & Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
- Addiction Research, Treatment & Training Center of Excellence, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Christina M. George
- Department of Cellular & Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Melissa Vitela
- Department of Cellular & Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Myrna Herrera-Rosales
- Department of Cellular & Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Mohamed S. Basiouny
- Department of Cellular & Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Wouter Koek
- Department of Psychiatry, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
- Department of Pharmacology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Lynette C. Daws
- Department of Cellular & Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
- Addiction Research, Treatment & Training Center of Excellence, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
- Department of Pharmacology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
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Abstract
INTRODUCTION In pharmacotherapy, drugs are mostly taken orally to be absorbed systemically from the small intestine, and some drugs are known to have preferential absorption sites in the small intestine. It would therefore be valuable to know the absorption sites of orally administered drugs and the influencing factors. Areas covered:In this review, the author summarizes the reported absorption sites of orally administered drugs, as well as, influencing factors and experimental techniques. Information on the main absorption sites and influencing factors can help to develop ideal drug delivery systems and more effective pharmacotherapies. Expert opinion: Various factors including: the solubility, lipophilicity, luminal concentration, pKa value, transporter substrate specificity, transporter expression, luminal fluid pH, gastrointestinal transit time, and intestinal metabolism determine the site-dependent intestinal absorption. However, most of the dissolved fraction of orally administered drugs including substrates for ABC and SLC transporters, except for some weakly basic drugs with higher pKa values, are considered to be absorbed sequentially from the proximal small intestine. Securing the solubility and stability of drugs prior to reaching to the main absorption sites and appropriate delivery rates of drugs at absorption sites are important goals for achieving effective pharmacotherapy.
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Affiliation(s)
- Teruo Murakami
- a Laboratory of Biopharmaceutics and Pharmacokinetics, Faculty of Pharmaceutical Sciences , Hiroshima International University , Hiroshima , Japan
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