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Haar G, Hrachova K, Wagner T, Boehm S, Schicker K. Impairment of exocytotic transmitter release by decynium-22 through an inhibition of ion channels. Front Pharmacol 2023; 14:1276100. [PMID: 37881182 PMCID: PMC10597664 DOI: 10.3389/fphar.2023.1276100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Accepted: 09/21/2023] [Indexed: 10/27/2023] Open
Abstract
Introduction: In addition to members of the family of Na+/Cl- dependent monoamine transporters, organic cation transporters (OCTs), in particular OCT3, as well as the plasma membrane monoamine transporter (PMAT) may contribute to neuronal reuptake of according neurotransmitters. As opposed to the numerous blockers of monoamine transporters, only a very limited number of specific blockers of OCT3 and PMAT are available. In fact, decynium-22 is the only blocking agent with micromolar affinities for both transport proteins, and this molecule is frequently used to establish roles of OCT3 and/or PMAT as targets for antidepressant drugs and psychostimulants, respectively. Methods/Results: To test for a function of these transporters in the sympathetic nervous system, uptake and release of [3H]1-methyl-4-phenylpyridinium (MPP+) was investigated in primary cultures of rat superior cervical ganglia. Uptake was reduced by cocaine or desipramine, blockers of the noradrenaline transporter, by about 70% and by corticosterone or β-estradiol, blockers of OCT3, by about 30%; decynium-22 achieved complete inhibition of uptake with half maximal effects at 3 μM. Depolarization dependent release was enhanced by corticosterone or β-estradiol, but reduced by decynium-22. As the latter effect is unlikely to be related to actions at OCT3 and/or PMAT, electrophysiological recordings were performed to reveal that decynium-22 inhibits action potential firing and currents through voltage activated calcium channels in superior cervical ganglion neurons. Discussion: These results demonstrate that decynium-22 can impair exocytotic neurotransmitter release by interfering with several types of ion channels. Such transporter-independent effects of decynium-22 that my interfere with basic neuronal functions need to be considered when interpreting results obtained with decynium-22 as prototypic inhibitor of transmitter reuptake via OCT3 and/or PMAT.
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Affiliation(s)
| | | | | | | | - Klaus Schicker
- Division of Neurophysiology and Neuropharmacology, Centre of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
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Gould GG, Barba-Escobedo PA, Horton RE, Daws LC. High Affinity Decynium-22 Binding to Brain Membrane Homogenates and Reduced Dorsal Camouflaging after Acute Exposure to it in Zebrafish. Front Pharmacol 2022; 13:841423. [PMID: 35754508 PMCID: PMC9218599 DOI: 10.3389/fphar.2022.841423] [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: 12/22/2021] [Accepted: 03/29/2022] [Indexed: 11/13/2022] Open
Abstract
Organic cation transporters (OCTs) are expressed in the mammalian brain, kidney, liver, placenta, and intestines, where they facilitate the transport of cations and other substrates between extracellular fluids and cells. Despite increasing reliance on ectothermic vertebrates as alternative toxicology models, properties of their OCT homologs transporting many drugs and toxins remain poorly characterized. Recently, in zebrafish (Danio rerio), two proteins with functional similarities to human OCTs were shown to be highly expressed in the liver, kidney, eye, and brain. This study is the first to characterize in vivo uptake to the brain and the high-affinity brain membrane binding of the mammalian OCT blocker 1-1'-diethyl-2,2'cyanine iodide (decynium-22 or D-22) in zebrafish. Membrane saturation binding of [3H] D-22 in pooled zebrafish whole brain versus mouse hippocampal homogenates revealed a high-affinity binding site with a KD of 5 ± 2.5 nM and Bmax of 1974 ± 410 fmol/mg protein in the zebrafish brain, and a KD of 3.3 ± 2.3 and Bmax of 704 ± 182 fmol/mg protein in mouse hippocampus. The binding of [3H] D-22 to brain membrane homogenates was partially blocked by the neurotoxic cation 1-methyl-4-phenylpyridinium (MPP+), a known OCT substrate. To determine if D-22 bath exposures reach the brain, zebrafish were exposed to 25 nM [3H] D-22 for 10 min, and 736 ± 68 ng/g wet weight [3H] D-22 was bound. Acute behavioral effects of D-22 in zebrafish were characterized in two anxiety-relevant tests. In the first cohort of zebrafish, 12.5, 25, or 50 mg/L D-22 had no effect on their height in the dive tank or entries and time spent in white arms of a light/dark plus maze. By contrast, 25 mg/L buspirone increased zebrafish dive tank top-dwelling (p < 0.05), an anticipated anxiolytic effect. However, a second cohort of zebrafish treated with 50 mg/L D-22 made more white arm entries, and females spent more time in white than controls. Based on these findings, it appears that D-22 bath treatments reach the zebrafish brain and have partial anxiolytic properties, reducing anti-predator dorsal camouflaging, without increasing vertical exploration. High-affinity binding of [3H] D-22 in zebrafish brain and mouse brain was similar, with nanomolar affinity, possibly at conserved OCT site(s).
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Affiliation(s)
- Georgianna G Gould
- Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States.,Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Priscilla A Barba-Escobedo
- Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States.,Department of Endodontics, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Rebecca E Horton
- Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States.,Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Lynette C Daws
- Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States.,Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States.,Department of Pharmacology, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
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3
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Benton KC, Lowry CA, Gasser PJ. Organic Cation Transporters and Nongenomic Glucocorticoid Action. Handb Exp Pharmacol 2021; 266:241-251. [PMID: 34104992 DOI: 10.1007/164_2021_493] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Corticosteroid hormones exert powerful influences on neuronal physiology and behavior by activating intracellular glucocorticoid receptors (GR) and mineralocorticoid receptors (MR), which act as ligand-gated transcription factors, altering gene expression. In addition to these genomic effects on physiology and behavior, which are usually delayed by minutes to hours, corticosteroid hormones also initiate rapid effects through diverse nongenomic mechanisms. One such mechanism involves the direct inhibition by corticosteroid hormones of monoamine transport mediated by the "uptake2" transporter, organic cation transporter 3 (OCT3), a high-capacity, low-affinity transporter for norepinephrine, epinephrine, dopamine, serotonin, and histamine. In this review we describe studies that demonstrate OCT3 expression and corticosterone-sensitive monoamine transport in the brain and present evidence supporting the hypothesis that corticosterone exerts rapid, nongenomic actions on glia and neurons, ultimately modulating physiology and behavior, by inhibiting OCT3-mediated monoamine clearance. We also describe the corticosteroid sensitivity of the other members of the uptake2 family and examine their potential contributions to nongenomic effects of corticosteroids in the brain.
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Affiliation(s)
- Kelsey C Benton
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI, USA
| | - Christopher A Lowry
- Department of Integrative Physiology, Center for Neuroscience, University of Colorado Boulder, Boulder, CO, USA
| | - Paul J Gasser
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI, USA.
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4
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Abstract
Catecholamines, including dopamine, norepinephrine, and epinephrine, are modulatory transmitters released from specialized neurons throughout the brain. Collectively, catecholamines exert powerful regulation of mood, motivation, arousal, and plasticity. Transporter-mediated uptake determines the peak concentration, duration, and physical spread of released catecholamines, thus playing key roles in determining the magnitude and duration of their modulatory effects. Most studies of catecholamine clearance have focused on the presynaptic high-affinity, low-capacity dopamine (DAT), and norepinephrine (NET) transporters, which are members of the uptake1 family of monoamine transporters. However, recent studies have demonstrated that members of the uptake2 family of monoamine transporters, including organic cation transporter 2 (OCT2), OCT3, and the plasma membrane monoamine transporter (PMAT) are expressed widely throughout the brain. In contrast to DAT and NET, these transporters have higher capacity and lower affinity for catecholamines and are multi-specific, each with the capacity to transport all catecholamines. The expression of these transporters in the brain suggests that they play significant roles in regulating catecholamine homeostasis. This review summarizes studies describing the anatomical distribution of OCT2, OCT3, and PMAT, their cellular and subcellular localization, and their contribution to the regulation of the clearance of catecholamines in the brain.
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5
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Kouyoumdzian NM, Rukavina Mikusic NL, Robbesaul GD, Gorzalczany SB, Carranza A, Trida V, Fernández BE, Choi MR. Acute infusion of angiotensin II regulates organic cation transporters function in the kidney: its impact on the renal dopaminergic system and sodium excretion. Hypertens Res 2020; 44:286-298. [PMID: 32934369 DOI: 10.1038/s41440-020-00552-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 07/13/2020] [Accepted: 08/06/2020] [Indexed: 12/21/2022]
Abstract
A close relationship between angiotensin II (ANG II) and the renal dopaminergic system (RDS) has been reported. Our aim was to study whether renal dopamine and ANG II can interact to modify renal sodium handling and then to elucidate the related mechanism. Anesthetized male Sprague-Dawley rats were used in experiments. ANG II, exogenous dopamine, and decynium-22 (or D-22, an isocyanine that specifically blocks electrogenic organic cation transporters, OCTs), were infused in vivo for 120 min. We analyzed renal and hemodynamic parameters, renal Na+, K+-ATPase levels, OCT activity, and urinary dopamine concentrations. We also evaluated the expression of D1 receptor, electroneutral organic cation transporters (OCTNs), and OCTs. ANG II decreased renal excretion of sodium in the presence of exogenous dopamine, increased Na+, K+-ATPase activity, and decreased the urinary dopamine concentration. D-22 treatment exacerbated the ANG II-mediated decrease in renal excretion of sodium and dopamine urine excretion but did not modify ANG II stimulation of Na+, K+-ATPase activity. The infusion of ANG II did not affect the expression of D1 receptor, OCTs, or OCTNs. However, the activity of OCTs was diminished by the presence of ANG II. Although ANG II did not alter the expression of D1 receptor, OCTs, and OCTNs in renal tissues, it modified the activity of OCTs and thereby decreased the urinary dopamine concentration, showing a novel mechanism by which ANG II decreases dopamine transport and its availability in the tubular lumen to stimulate D1 receptor. This study demonstrates a relationship between ANG II and dopamine, where both agents counteract their effects on sodium excretion.
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Affiliation(s)
- Nicolás M Kouyoumdzian
- Universidad de Buenos Aires. CONICET, Instituto Alberto C. Taquini de Investigaciones en Medicina Traslacional (IATIMET), Buenos Aires, Argentina.
| | - Natalia L Rukavina Mikusic
- Universidad de Buenos Aires. CONICET, Instituto Alberto C. Taquini de Investigaciones en Medicina Traslacional (IATIMET), Buenos Aires, Argentina
| | - Gabriel D Robbesaul
- Universidad de Buenos Aires. CONICET, Instituto Alberto C. Taquini de Investigaciones en Medicina Traslacional (IATIMET), Buenos Aires, Argentina
| | - Susana B Gorzalczany
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Farmacología, Cátedra de Farmacología, Buenos Aires, Argentina
| | - Andrea Carranza
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Farmacología, Cátedra de Farmacología, Buenos Aires, Argentina
| | - Verónica Trida
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Bioquímica Clínica, Cátedra de Bioquímica Clínica, Buenos Aires, Argentina
| | - Belisario E Fernández
- Instituto Universitario de Ciencias de la Salud, Fundación H.A. Barceló, Buenos Aires, Argentina
| | - Marcelo R Choi
- Universidad de Buenos Aires. CONICET, Instituto Alberto C. Taquini de Investigaciones en Medicina Traslacional (IATIMET), Buenos Aires, Argentina.,Instituto Universitario de Ciencias de la Salud, Fundación H.A. Barceló, Buenos Aires, Argentina.,Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Ciencias Biológicas, Cátedra de Anatomía e Histología, Buenos Aires, Argentina
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6
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Bowman MA, Mitchell NC, Owens WA, Horton RE, Koek W, Daws LC. Effect of concurrent organic cation transporter blockade on norepinephrine clearance inhibiting- and antidepressant-like actions of desipramine and venlafaxine. Eur J Pharmacol 2020; 883:173285. [PMID: 32697958 PMCID: PMC10092728 DOI: 10.1016/j.ejphar.2020.173285] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Revised: 06/10/2020] [Accepted: 06/15/2020] [Indexed: 12/26/2022]
Abstract
Depression is a major health problem for which most patients are not effectively treated. This underscores a need to identify new targets for the development of antidepressants with improved efficacy. Studies have shown that blockade of low-affinity/high-capacity transporters, such as organic cation transporters (OCTs) and the plasma membrane monoamine transporter (PMAT), with decynium-22 can produce antidepressant-like effects and inhibit serotonin clearance in brain when the serotonin transporter is pharmacologically or genetically compromised. In vitro studies show that OCTs/PMAT are also capable of norepinephrine transport, raising the possibility that decynium-22 might enhance the antidepressant-like effects of norepinephrine transporter inhibitors. Using in vivo electrochemistry, we show that local administration of decynium-22 into dentate gyrus of hippocampus enhanced the ability of the norepinephrine transporter blocker, desipramine, but not the dual norepinephrine/serotonin transporter blocker venlafaxine, to inhibit norepinephrine clearance. In parallel, systemic administration of decynium-22 (0.32 mg/kg) enhanced the antidepressant-like effects of desipramine (32 mg/kg), but not those of venlafaxine, in the tail suspension test, underscoring the heterogeneous response of mice to antidepressants, including those that share similar mechanisms of action. Systemic administration of normetanephrine, a potent blocker of OCT3, failed to potentiate the antidepressant-like effects of desipramine, suggesting that the actions of decynium-22 to augment the antidepressant-like effects of desipramine are likely mediated by another OCT isoform and/or PMAT. Taken together with existing literature, concurrent blockade of OCTs and/or PMAT merits further investigation as an adjunctive therapeutic for desipramine-like antidepressant drugs.
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Affiliation(s)
- Melodi A Bowman
- Department of Cellular and Integrative Physiology, University of Texas Health, San Antonio, TX, USA
| | - Nathan C Mitchell
- Department of Cellular and Integrative Physiology, University of Texas Health, San Antonio, TX, USA
| | - W Anthony Owens
- Department of Cellular and Integrative Physiology, University of Texas Health, San Antonio, TX, USA
| | - Rebecca E Horton
- Department of Cellular and Integrative Physiology, University of Texas Health, San Antonio, TX, USA
| | - Wouter Koek
- Department of Psychiatry, University of Texas Health, San Antonio, TX, USA; Department of Pharmacology, University of Texas Health, San Antonio, TX, USA
| | - 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.
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7
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Antidepressant efficacy of a selective organic cation transporter blocker in a mouse model of depression. Mol Psychiatry 2020; 25:1245-1259. [PMID: 31619760 DOI: 10.1038/s41380-019-0548-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Revised: 08/08/2019] [Accepted: 08/19/2019] [Indexed: 12/28/2022]
Abstract
Current antidepressants act principally by blocking monoamine reuptake by high-affinity transporters in the brain. However, these antidepressants show important shortcomings such as slow action onset and limited efficacy in nearly a third of patients with major depression disorder. Here, we report the development of a prodrug targeting organic cation transporters (OCT), atypical monoamine transporters recently implicated in the regulation of mood. Using molecular modeling, we designed a selective OCT2 blocker, which was modified to increase brain penetration. This compound, H2-cyanome, was tested in a rodent model of chronic depression induced by 7-week corticosterone exposure. In male mice, prolonged administration of H2-cyanome induced positive effects on several behaviors mimicking symptoms of depression, including anhedonia, anxiety, social withdrawal, and memory impairment. Importantly, in this validated model, H2-cyanome compared favorably with the classical antidepressant fluoxetine, with a faster action on anhedonia and better anxiolytic effects. Integrated Z-scoring across these depression-like variables revealed a lower depression score for mice treated with H2-cyanome than for mice treated with fluoxetine for 3 weeks. Repeated H2-cyanome administration increased ventral tegmental area dopaminergic neuron firing, which may underlie its rapid action on anhedonia. H2-cyanome, like fluoxetine, also modulated several intracellular signaling pathways previously involved in antidepressant response. Our findings provide proof-of-concept of antidepressant efficacy of an OCT blocker, and a mechanistic framework for the development of new classes of antidepressants and therapeutic alternatives for resistant depression and other psychiatric disturbances such as anxiety.
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8
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Electrophysiological Characterization of Novel Effects of the Uptake-2 Blocker Decynium-22 (D-22) on Dopaminergic Neurons in the Substantia Nigra Pars Compacta. Neuroscience 2019; 396:154-165. [PMID: 30447392 DOI: 10.1016/j.neuroscience.2018.11.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 10/23/2018] [Accepted: 11/07/2018] [Indexed: 01/11/2023]
Abstract
Extracellular levels of dopamine (DA) and other monoamines in the brain depend not only on the classic transporters encoded by SLC6A gene family such as DAT, NET and SERT, but also a more recently identified group of low-affinity/high-capacity 'Uptake-2' transporters, mainly OCT3 and PMAT. The most frequently used pharmacological tool in functional studies of Uptake-2 is decynium-22 (D-22) known to block these transporters. However, the effectiveness of this drug in enhancing extracellular DA remains uncertain. Our aim was to test the hypothesis that D-22 increases extracellular levels of DA released from the somatodendritic region of dopaminergic neurons in the substantia nigra pars compacta (SNc) by reducing the OCT3/PMAT-dependent component of DA uptake. Extracellular DA was assessed indirectly, by evoking D2-IPSCs in SNc neurons following stimulated release of this neurotransmitter in midbrain slices obtained from mice. Recordings were conducted after partial inhibition of DAT with nomifensine, and after application of L-DOPA which increased the releasable DA pool. Contrary to our expectations, D-22 reduced, rather than increased, the amplitude of D2-IPSCs. Other effects included inhibition of GABAB-IPSCs and Ih current, and a reduction in firing frequency of nigral neurons. These results show that in addition to the previously known non-specific inhibitory action on α1 adrenoceptors, D-22 exerts additional off-target effects by inhibiting dopaminergic and GABAergic synaptic transmission in the SNc and the spontaneous (pacemaker) activity of nigral neurons. It remains to be established if these novel effects contribute to a reduction in spontaneous locomotor activity reported in previous studies after systemic drug administration.
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Krause-Heuer AM, Fraser-Spears R, Dobrowolski JC, Ashford ME, Wyatt NA, Roberts MP, Gould GG, Cheah WC, Ng CKL, Bhadbhade M, Zhang B, Greguric I, Wheate NJ, Kumar N, Koek W, Callaghan PD, Daws LC, Fraser BH. Evaluation of the antidepressant therapeutic potential of isocyanine and pseudoisocyanine analogues of the organic cation decynium-22. Eur J Med Chem 2017. [PMID: 28624702 DOI: 10.1016/j.ejmech.2017.06.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Herein we describe the synthesis and evaluation of antidepressant properties of seven analogues (1-7) of the low affinity/high capacity transporter blocker decynium-22 (D-22). All analogues (1-7) were synthesized via base promoted coupling reactions between N-alkylated-2-methylquinolinium iodides or N-alkylated-4-methylquinolinium iodides and electrophilic N-alkylated-2-iodoquinolinium iodides. All final compounds were purified by re-crystallization or preparative HPLC and initial evaluation studies included; 1) screening for in vitro α1-adrenoceptor activity (a property that can lead to unwanted side-effects), 2) measuring antidepressant-like activity in a mouse tail suspension test (TST), and 3) measuring effects upon mouse locomotion. The results showed some analogues have lower affinities at α1-adrenoceptors compared to D-22 and showed antidepressant-like activity without the need for co-administration of SSRIs. Additionally, many analogues did not affect mouse locomotion to the same extent as D-22. Plans for additional evaluations of these promising analogues, including measurement of antidepressant-like activity with co-administration of selective serotonin re-uptake inhibitors (SSRIs), are outlined.
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Affiliation(s)
- Anwen M Krause-Heuer
- The Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC NSW 2232, Australia
| | - Rheaclare Fraser-Spears
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, USA
| | | | - Mark E Ashford
- The Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC NSW 2232, Australia
| | - 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
| | - Georgianna G Gould
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, USA
| | - Wai-Ching Cheah
- The Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC NSW 2232, Australia
| | - Clarissa K L Ng
- The Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC NSW 2232, Australia
| | - Mohan Bhadbhade
- School of Chemistry, University of New South Wales, Sydney, NSW 2052, Australia
| | - Bo Zhang
- The Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC NSW 2232, Australia; Faculty of Pharmacy, University of Sydney, Sydney, NSW 2006, Australia
| | - Ivan Greguric
- The Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC NSW 2232, Australia
| | - Nial J Wheate
- Faculty of Pharmacy, University of Sydney, Sydney, NSW 2006, Australia
| | - Naresh Kumar
- School of Chemistry, University of New South Wales, Sydney, NSW 2052, Australia
| | - Wouter Koek
- Department of Psychiatry, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, USA; Department of Pharmacology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, USA
| | - Paul D Callaghan
- The Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC NSW 2232, Australia
| | - Lynette C Daws
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, USA; Department of Pharmacology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, USA.
| | - Benjamin H Fraser
- The Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC NSW 2232, Australia.
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10
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Yang C, Leung GPH. Equilibrative Nucleoside Transporters 1 and 4: Which One Is a Better Target for Cardioprotection Against Ischemia-Reperfusion Injury? J Cardiovasc Pharmacol 2015; 65:517-21. [PMID: 26070128 PMCID: PMC4461397 DOI: 10.1097/fjc.0000000000000194] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2014] [Accepted: 11/14/2014] [Indexed: 01/04/2023]
Abstract
The cardioprotective effects of adenosine and adenosine receptor agonists have been studied extensively. However, their therapeutic outcomes in ischemic heart disease are limited by systemic side effects such as hypotension, bradycardia, and sedation. Equilibrative nucleoside transporter (ENT) inhibitors may be an alternative. By reducing the uptake of extracellular adenosine, ENT1 inhibitors potentiate the cardioprotective effect of endogenous adenosine. They have fewer systemic side effects because they selectively increase the extracellular adenosine levels in ischemic tissues undergoing accelerated adenosine formation. Nonetheless, long-term inhibition of ENT1 may adversely affect tissues that have low capacity for de novo nucleotide biosynthesis. ENT1 inhibitors may also affect the cellular transport, and hence the efficacy, of anticancer and antiviral nucleoside analogs used in chemotherapy. It has been proposed that ENT4 may also contribute to the regulation of extracellular adenosine in the heart, especially under the acidotic conditions associated with ischemia. Like ENT1 inhibitors, ENT4 inhibitors should work specifically on ischemic tissues. Theoretically, ENT4 inhibitors do not affect tissues that rely on ENT1 for de novo nucleotide synthesis. They also have no interaction with anticancer and antiviral nucleosides. Development of specific ENT4 inhibitors may open a new avenue in research on ischemic heart disease therapy.
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Affiliation(s)
- Cui Yang
- Ethnic Drug Screening & Pharmacology Center, Key Laboratory of Chemistry in Ethnic Medicinal Resources, State Ethnic Affairs Commission & Ministry of Education, Yunnan Minzu University, Kunming, China; and
| | - George P. H. Leung
- Department of Pharmacology and Pharmacy, The University of Hong Kong, Hong Kong, China
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Hosford PS, Millar J, Ramage AG. Cardiovascular afferents cause the release of 5-HT in the nucleus tractus solitarii; this release is regulated by the low- (PMAT) not the high-affinity transporter (SERT). J Physiol 2015; 593:1715-29. [PMID: 25694117 PMCID: PMC4386968 DOI: 10.1113/jphysiol.2014.285312] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Accepted: 01/16/2015] [Indexed: 12/31/2022] Open
Abstract
The nucleus tractus solitarii (NTS) integrates inputs from cardiovascular afferents and thus is crucial for cardiovascular homeostasis. These afferents primarily release glutamate, although 5-HT has also been shown to play a role in their actions. Using fast-cyclic voltammetry, an increase in 5-HT concentrations (range 12-50 nm) could be detected in the NTS in anaesthetized rats in response to electrical stimulation of the vagus and activation of cardiopulmonary, chemo- and baroreceptor reflexes. This 5-HT signal was not potentiated by the serotonin transporter (SERT) or the noradrenaline transporter (NET) inhibitors citalopram and desipramine (1 mg kg(-1) ). However, decynium-22 (600 μg kg(-1) ), an organic cation 3 transporter (OCT3)/plasma membrane monoamine transporter (PMAT) inhibitor, increased the 5-HT signal by 111 ± 21% from 29 ± 10 nm. The effectiveness of these inhibitors was tested against the removal time of 5-HT and noradrenaline applied by microinjection to the NTS. Citalopram and decynium-22 attenuated the removal of 5-HT but not noradrenaline, whereas desipramine had the reverse action. The OCT3 inhibitor corticosterone (10 mg kg(-1) ) had no effect. Blockade of glutamate receptors with topical kynurenate (10-50 nm) reduced the vagally evoked 5-HT signal by 50%, indicating that this release was from at least two sources. It is concluded that vagally evoked 5-HT release is under the regulation of the high-capacity, low-affinity transporter PMAT, not the low-capacity, high-affinity transporter SERT. This is the first demonstration that PMAT may be playing a physiological role in the regulation of 5-HT transmission and this could indicate that 5-HT is acting, in part, as a volume transmitter within the NTS.
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Affiliation(s)
- Patrick S Hosford
- Department of Neuroscience, Physiology and Pharmacology, University College LondonGower Street, London, WC1E 6BT, UK
| | - Julian Millar
- Department of Medical Education, Queen Mary's School of Medicine and DentistryWhitechapel, London, E1 2AD, UK
| | - Andrew G Ramage
- Department of Neuroscience, Physiology and Pharmacology, University College LondonGower Street, London, WC1E 6BT, UK
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Marcinkiewcz CA, Devine DP. Modulation of OCT3 expression by stress, and antidepressant-like activity of decynium-22 in an animal model of depression. Pharmacol Biochem Behav 2015; 131:33-41. [PMID: 25597272 DOI: 10.1016/j.pbb.2015.01.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2014] [Revised: 01/08/2015] [Accepted: 01/11/2015] [Indexed: 10/24/2022]
Abstract
The organic cation transporter-3 (OCT3) is a glucocorticoid-sensitive uptake mechanism that has been shown to regulate the bioavailability of monoamines in brain regions that are implicated in the pathophysiology of depression. In the present study, the relative impacts of acute stress alone and acute stress with a history of repeated stress (chronic+acute) were evaluated in two strains of rats: the stress-vulnerable Wistar-Kyoto (WKY) strain and the somewhat more stress-resilient Long-Evans (LE) strain. OCT3 mRNA was significantly upregulated in the hippocampus of LE rats 2h after exposure to acute restraint stress, but not in acutely-restrained rats with a history of repeated social defeat stress. WKY rats exhibited a very different pattern. OCT3 mRNA was unaffected by acute restraint stress alone but was robustly upregulated after repeated+acute stress. There was also a corresponding increase in cytosolic OCT3 protein following repeated+acute stress in WKY rats 3h after presentation of the acute stressor. These results are consistent with the hypothesis that altered expression of the OCT3 may play a role in stress coping, and strain differences in regulation of this expression may contribute to differences in physiological and behavioral responses to stress. Furthermore, the OCT3 inhibitor, decynium 22 (1 and 10μg/kg, i.p.) reduced immobility of WKY rats, but not that of LE rats, in the forced swim test, suggesting that blockade of the OCT3 has antidepressant-like effects. Since WKY rats also appear to be resistant to the behavioral effects of traditional antidepressants, this also suggests that OCT3 antagonism may be an alternative therapeutic strategy for the treatment of depression in individuals who do not respond to conventional antidepressants.
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Affiliation(s)
- C A Marcinkiewcz
- University of Florida, Department of Neuroscience, McKnight Brain Institute, Gainesville, FL 32610-0015, USA
| | - D P Devine
- University of Florida, Department of Neuroscience, McKnight Brain Institute, Gainesville, FL 32610-0015, USA; University of Florida, Department of Psychology, Behavioral and Cognitive Neuroscience Program, Gainesville, FL 32611-2250, USA.
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Decynium-22 enhances SSRI-induced antidepressant-like effects in mice: uncovering novel targets to treat depression. J Neurosci 2013; 33:10534-43. [PMID: 23785165 DOI: 10.1523/jneurosci.5687-11.2013] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Mood disorders cause much suffering and lost productivity worldwide, compounded by the fact that many patients are not effectively treated by currently available medications. The most commonly prescribed antidepressant drugs are the selective serotonin (5-HT) reuptake inhibitors (SSRIs), which act by blocking the high-affinity 5-HT transporter (SERT). The increase in extracellular 5-HT produced by SSRIs is thought to be critical to initiate downstream events needed for therapeutic effects. A potential explanation for their limited therapeutic efficacy is the recently characterized presence of low-affinity, high-capacity transporters for 5-HT in brain [i.e., organic cation transporters (OCTs) and plasma membrane monoamine transporter], which may limit the ability of SSRIs to increase extracellular 5-HT. Decynium-22 (D-22) is a blocker of these transporters, and using this compound we uncovered a significant role for OCTs in 5-HT uptake in mice genetically modified to have reduced or no SERT expression (Baganz et al., 2008). This raised the possibility that pharmacological inactivation of D-22-sensitive transporters might enhance the neurochemical and behavioral effects of SSRIs. Here we show that in wild-type mice D-22 enhances the effects of the SSRI fluvoxamine to inhibit 5-HT clearance and to produce antidepressant-like activity. This antidepressant-like activity of D-22 was attenuated in OCT3 KO mice, whereas the effect of D-22 to inhibit 5-HT clearance in the CA3 region of hippocampus persisted. Our findings point to OCT3, as well as other D-22-sensitive transporters, as novel targets for new antidepressant drugs with improved therapeutic potential.
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Amphoux A, Millan MJ, Cordi A, Bönisch H, Vialou V, Mannoury la Cour C, Dupuis DS, Giros B, Gautron S. Inhibitory and facilitory actions of isocyanine derivatives at human and rat organic cation transporters 1, 2 and 3: A comparison to human α1- and α2-adrenoceptor subtypes. Eur J Pharmacol 2010; 634:1-9. [DOI: 10.1016/j.ejphar.2010.02.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2009] [Revised: 01/25/2010] [Accepted: 02/09/2010] [Indexed: 01/11/2023]
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