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Kawanishi S, Kojima K, Shibukawa A, Sakamoto M, Sudo Y. Detection of Membrane Potential-Dependent Rhodopsin Fluorescence Using Low-Intensity Light Emitting Diode for Long-Term Imaging. ACS OMEGA 2023; 8:4826-4834. [PMID: 36777568 PMCID: PMC9910066 DOI: 10.1021/acsomega.2c06980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Accepted: 01/13/2023] [Indexed: 06/18/2023]
Abstract
Microbial rhodopsin is a family of photoreceptive membrane proteins that commonly consist of a seven-transmembrane domain and a derivative of vitamin-A, retinal, as a chromophore. In 2011, archaeorhodopsin-3 (AR3) was shown to exhibit voltage-dependent fluorescence changes in mammalian cells. Since then, AR3 and its variants have been used as genetically encoded voltage indicators, in which mostly intense laser stimulation (1-1000 W/cm2) is used for the detection of dim fluorescence of rhodopsin, leading to high spatiotemporal resolution. However, intense laser stimulation potentially causes serious cell damage, particularly during long-term imaging over minutes. In this study, we present the successful detection of voltage-sensitive fluorescence of AR3 and its high fluorescence mutant Archon1 in a variety of mammalian cell lines using low-intensity light emitting diode stimulation (0.15 W/cm2) with long exposure time (500 ms). The detection system enables real-time imaging of drug-induced slow changes in voltage within the cells for minutes harmlessly and without fluorescence bleaching. Therefore, we demonstrate a method to quantitatively understand the dynamics of slow changes in membrane voltage on long time scales.
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Affiliation(s)
- Shiho Kawanishi
- Graduate
School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan
| | - Keiichi Kojima
- Graduate
School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan
- Faculty
of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan
| | - Atsushi Shibukawa
- Graduate
School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan
| | - Masayuki Sakamoto
- Department
of Optical Neural and Molecular Physiology, Graduate School of Biostudies, Kyoto University, Kyoto 606-8507, Japan
| | - Yuki Sudo
- Graduate
School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan
- Faculty
of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan
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Ashok AH, Mizuno Y, Howes OD. Tobacco smoking and dopaminergic function in humans: a meta-analysis of molecular imaging studies. Psychopharmacology (Berl) 2019; 236:1119-1129. [PMID: 30887059 PMCID: PMC6591186 DOI: 10.1007/s00213-019-05196-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Accepted: 02/07/2019] [Indexed: 12/21/2022]
Abstract
RATIONALE About 1.1 billion people smoke tobacco globally and tobacco-related health care costs 1.8% of GDP in many countries. The majority of people are unable to quit smoking despite pharmacological intervention, highlighting the need to understand the pathophysiology associated with tobacco smoking to aid the development of new therapeutics. The reinforcing effects of tobacco smoking are thought to be mediated by the dopamine system. However, the nature of dopamine dysfunction seen in smokers is unclear. OBJECTIVE To determine the nature and robustness of the evidence for dopaminergic alterations in smokers. METHODS The entire MEDLINE, EMBASE, and PsycINFO databases were searched for studies from inception date to November 18, 2018. In vivo human molecular imaging studies of dopamine measures (dopamine synthesis or release capacity, transporter levels, receptor levels) in tobacco smokers were selected. Demographic, clinical, and imaging measures were extracted from each study and meta-analyses, and sensitivity analyses were conducted. RESULTS Fourteen studies met inclusion criteria comprising a total sample of 219 tobacco smokers and 297 controls. The meta-analysis showed a significant reduction in dopamine transporter availability in the smokers relative to controls with an effect size of - 0.72 ([95% CI, - 1.38 to - 0.05], p = 0.03). However, there was no difference in D2/3 receptor availability in smokers relative to controls (d = -0.16 ([95% CI, - 0.42 to 0.1], p = 0.23). There were insufficient studies for meta-analysis of other measures. However, findings from the published studies indicated blunted dopamine release and lower D1 receptor availability, while findings for dopamine synthesis capacity were inconsistent. CONCLUSION Our data indicate that striatal dopamine transporter availability is lower but D2/3 receptors are unaltered in smokers relative to controls. We discuss the putative mechanisms underlying this and their implications.
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Affiliation(s)
- Abhishekh H. Ashok
- Psychiatric Imaging Group, MRC London Institute of Medical Sciences Centre (LMS), Du Cane Road, London, W12 0NN UK ,Psychiatric Imaging Group, Faculty of Medicine, Imperial College London, Institute of Clinical Sciences (ICS), Du Cane Road, London, UK ,Department of Psychosis Studies, Institute of Psychiatry, Psychology & Neuroscience, King’s College London, 16 De Crespigny Park, London, SE5 8AB UK
| | - Yuya Mizuno
- Department of Psychosis Studies, Institute of Psychiatry, Psychology & Neuroscience, King’s College London, 16 De Crespigny Park, London, SE5 8AB UK ,Department of Neuropsychiatry, Keio University School of Medicine, Tokyo, Japan
| | - Oliver D. Howes
- Psychiatric Imaging Group, MRC London Institute of Medical Sciences Centre (LMS), Du Cane Road, London, W12 0NN UK ,Psychiatric Imaging Group, Faculty of Medicine, Imperial College London, Institute of Clinical Sciences (ICS), Du Cane Road, London, UK ,Department of Psychosis Studies, Institute of Psychiatry, Psychology & Neuroscience, King’s College London, 16 De Crespigny Park, London, SE5 8AB UK
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Hovde MJ, Larson GH, Vaughan RA, Foster JD. Model systems for analysis of dopamine transporter function and regulation. Neurochem Int 2018; 123:13-21. [PMID: 30179648 DOI: 10.1016/j.neuint.2018.08.015] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2018] [Revised: 08/23/2018] [Accepted: 08/31/2018] [Indexed: 02/07/2023]
Abstract
The dopamine transporter (DAT) plays a critical role in dopamine (DA) homeostasis by clearing transmitter from the extraneuronal space after vesicular release. DAT serves as a site of action for a variety of addictive and therapeutic reuptake inhibitors, and transport dysfunction is associated with transmitter imbalances in disorders such as schizophrenia, attention deficit hyperactive disorder, bipolar disorder, and Parkinson disease. In this review, we describe some of the model systems that have been used for in vitro analyses of DAT structure, function and regulation, and discuss a potential relationship between transporter kinetic values and membrane cholesterol.
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Affiliation(s)
- Moriah J Hovde
- Department of Biomedical Sciences, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, ND, 58202, USA
| | - Garret H Larson
- Department of Biomedical Sciences, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, ND, 58202, USA
| | - Roxanne A Vaughan
- Department of Biomedical Sciences, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, ND, 58202, USA
| | - James D Foster
- Department of Biomedical Sciences, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, ND, 58202, USA.
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Kurauchi Y, Hisatsune A, Isohama Y, Sawa T, Akaike T, Katsuki H. Nitric oxide/soluble guanylyl cyclase signaling mediates depolarization-induced protection of rat mesencephalic dopaminergic neurons from MPP⁺ cytotoxicity. Neuroscience 2012; 231:206-15. [PMID: 23238575 DOI: 10.1016/j.neuroscience.2012.11.044] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Revised: 11/09/2012] [Accepted: 11/24/2012] [Indexed: 12/30/2022]
Abstract
Neuronal electrical activity has been known to affect the viability of neurons in the central nervous system. Here we show that long-lasting membrane depolarization induced by elevated extracellular K(+) recruits nitric oxide (NO)/soluble guanylyl cyclase/protein kinase G signaling pathway, induces 8-nitroguanosine 3',5'-cyclic monophosphate (8-nitro-cGMP)-mediated protein S-guanylation, and confers dopaminergic neuroprotection. Treatment of primary mesencephalic cell cultures with 1-methyl-4-phenylpyridinium (MPP(+)) for 72 h decreased the number of dopaminergic neurons, whereas the cell loss was markedly inhibited by elevated extracellular concentration of K(+) (+40 mM). The neuroprotective effect of elevated extracellular K(+) was significantly attenuated by tetrodotoxin (a Na(+) channel blocker), amlodipine (a voltage-dependent Ca(2+) channel blocker), N(ω)-nitro-l-arginine methyl ester (l-NAME) (a nitric oxide synthase inhibitor), 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) (a soluble guanylyl cyclase inhibitor), and KT5823 or Rp-8-bromo-β-phenyl-1,N(2)-ethenoguanosine 3',5'-cyclic monophosphorothioate (Rp-8-Br-PET-cGMPS) (protein kinase G inhibitors). Elevated extracellular K(+) increased 8-nitro-cGMP production resulting in the induction of protein S-guanylation in cells in mesencephalic cultures including dopaminergic neurons. In addition, exogenous application of 8-nitro-cGMP protected dopaminergic neurons from MPP(+) cytotoxicity, which was prevented by zinc protoporphyrin IX, an inhibitor of heme oxygenase-1 (HO-1). Zinc protoporphyrin IX also inhibited the neuroprotective effect of elevated extracellular K(+). On the other hand, KT5823 or Rp-8-Br-PET-cGMPS did not inhibit the induction of HO-1 protein expression by 8-nitro-cGMP, although these protein kinase G inhibitors abrogated the neuroprotective effect of 8-nitro-cGMP. These results suggest that protein S-guanylation (leading to HO-1 induction) as well as canonical protein kinase G signaling pathway plays an important role in NO-mediated, activity-dependent dopaminergic neuroprotection.
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Affiliation(s)
- Y Kurauchi
- Department of Chemico-Pharmacological Sciences, Graduate School of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-honmachi, Chuo-ku, Kumamoto 862-0973, Japan
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Cholinergic modulation of locomotion and striatal dopamine release is mediated by alpha6alpha4* nicotinic acetylcholine receptors. J Neurosci 2010; 30:9877-89. [PMID: 20660270 DOI: 10.1523/jneurosci.2056-10.2010] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Dopamine (DA) release in striatum is governed by firing rates of midbrain DA neurons, striatal cholinergic tone, and nicotinic ACh receptors (nAChRs) on DA presynaptic terminals. DA neurons selectively express alpha6* nAChRs, which show high ACh and nicotine sensitivity. To help identify nAChR subtypes that control DA transmission, we studied transgenic mice expressing hypersensitive alpha6(L9'S)* receptors. alpha6(L9'S) mice are hyperactive, travel greater distance, exhibit increased ambulatory behaviors such as walking, turning, and rearing, and show decreased pausing, hanging, drinking, and grooming. These effects were mediated by alpha6alpha4* pentamers, as alpha6(L9'S) mice lacking alpha4 subunits displayed essentially normal behavior. In alpha6(L9'S) mice, receptor numbers are normal, but loss of alpha4 subunits leads to fewer and less sensitive alpha6* receptors. Gain-of-function nicotine-stimulated DA release from striatal synaptosomes requires alpha4 subunits, implicating alpha6alpha4beta2* nAChRs in alpha6(L9'S) mouse behaviors. In brain slices, we applied electrochemical measurements to study control of DA release by alpha6(L9'S) nAChRs. Burst stimulation of DA fibers elicited increased DA release relative to single action potentials selectively in alpha6(L9'S), but not WT or alpha4KO/alpha6(L9'S), mice. Thus, increased nAChR activity, like decreased activity, leads to enhanced extracellular DA release during phasic firing. Bursts may directly enhance DA release from alpha6(L9'S) presynaptic terminals, as there was no difference in striatal DA receptor numbers or DA transporter levels or function in vitro. These results implicate alpha6alpha4beta2* nAChRs in cholinergic control of DA transmission, and strongly suggest that these receptors are candidate drug targets for disorders involving the DA system.
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Naha N, Lee HY, Hwang JS, Bahk JY, Park MS, Lee SY, Kim SH, Kim MO. Nicotine tolerance to PC12 cell line: acute and chronic exposures modulate dopamine D2 receptor and tyrosine hydroxylase expression. Neurol Res 2009; 31:289-99. [PMID: 19406037 DOI: 10.1179/174313209x382403] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
PC12 is a clonal cell line from chromaffin tumor of rat adrenal pheochromocytoma that releases catecholamine including dopamine, which via interaction with its receptor (D(1) and D(2) receptor), is known to be involved in reward and reinforcement properties of many addictive drugs like nicotine. Nicotine tolerance is the key aspect of nicotine addiction. However, nicotine tolerance on dopamine receptors in PC12 cell line is poorly understood. In this paper, we have demonstrated the tolerance to acute and chronic nicotine administrations on PC12 cell line on the basis of the expressions of dopamine receptors and tyrosine hydroxylase, the rate-limiting enzyme of dopamine biosynthesis, by Western blot, immunohistochemistry and in situ hybridization. In vitro treatment of nicotine resulted in similar expressional changes of dopamine D(2) receptor and tyrosine hydroxylase at protein and mRNA levels in dose- and time-dependent manner, whereas dopamine D(1) receptor did not reveal any positive output. Moreover, moderate to strong signals were obtained from 0.1 to 10 microM of nicotine concentrations and the signals were gradually decreased at 100 and 1000 microM nicotine concentrations relative to the untreated control cell line. Therefore, this study implied a new approach towards nicotine tolerance which is likely to be related to the modulation of dopamine D(2) receptor and tyrosine hydroxylase expressions by chronic and acute nicotine exposures in PC12 cell line.
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Affiliation(s)
- Nibedita Naha
- Division of Life Science, Applied Life Science (Brain Korea 21 and EB-NCRC), Gyeongsang National University, Jinju 660-701, South Korea
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Alyea RA, Watson CS. Nongenomic mechanisms of physiological estrogen-mediated dopamine efflux. BMC Neurosci 2009; 10:59. [PMID: 19531209 PMCID: PMC2708169 DOI: 10.1186/1471-2202-10-59] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2008] [Accepted: 06/16/2009] [Indexed: 01/01/2023] Open
Abstract
Background Neurological diseases and neuropsychiatric disorders that vary depending on female life stages suggest that sex hormones may influence the function of neurotransmitter regulatory machinery such as the dopamine transporter (DAT). Results In this study we tested the rapid nongenomic effects of several physiological estrogens [estradiol (E2), estrone (E1), and estriol (E3)] on dopamine efflux via the DAT in a non-transfected, NGF-differentiated, rat pheochromocytoma (PC12) cell model that expresses membrane estrogen receptors (ERs) α, β, and GPR30. We examined kinase, ionic, and physical interaction mechanisms involved in estrogenic regulation of the DAT function. E2-mediated dopamine efflux is DAT-specific and not dependent on extracellular Ca2+-mediated exocytotic release from vesicular monoamine transporter vesicles (VMATs). Using kinase inhibitors we also showed that E2-mediated dopamine efflux is dependent on protein kinase C and MEK activation, but not on PI3K or protein kinase A. In plasma membrane there are ligand-independent associations of ERα and ERβ (but not GPR30) with DAT. Conditions which cause efflux (a 9 min 10-9 M E2 treatment) cause trafficking of ERα (stimulatory) to the plasma membrane and trafficking of ERβ (inhibitory) away from the plasma membrane. In contrast, E1 and E3 can inhibit efflux with a nonmonotonic dose pattern, and cause DAT to leave the plasma membrane. Conclusion Such mechanisms explain how gender biases in some DAT-dependent diseases can occur.
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Affiliation(s)
- Rebecca A Alyea
- Department of Biochemistry & Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555-0645, USA.
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8
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Kao YY, Lai HL, Hwang MJ, Chern Y. An Important Functional Role of the N Terminus Domain of Type VI Adenylyl Cyclase in Gαi-mediated Inhibition. J Biol Chem 2004; 279:34440-8. [PMID: 15192109 DOI: 10.1074/jbc.m401952200] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We show herein that removal of the first 86 amino acids (aa) of the N terminus (designated N) of type VI adenylyl cyclase (ACVI) caused the resultant ACVI mutant (ACVI-DeltaA87) to be more greatly inhibited by a Galpha(i)-coupled receptor or activated Galpha(i) protein. Moreover, in vitro binding of the full-length N and C1a domain (designated C1a), which interacts with Galpha(i), was detected. A truncated N terminus (aa 1-86) also interacted with C1a, suggesting that the C1a-interacting region is located within aa 1-86. Mutation analyses further revealed that N might interact with C1a in the region (aa 434-505) where Galpha(i) is bound. Mutations of two residues (Leu-472 and Val-476) located in this N-binding region of C1a suppressed the interaction between recombinant N and C1a and markedly reduced Galpha(i)-mediated inhibition of ACVI-DeltaA87. Further biochemical analyses of the effect of internal mutations of Leu-472/Val-476 on Galpha(i)-mediated inhibition of wild-type ACVI and ACVI-DeltaA87 suggested that N modulates the Galpha(i)-mediated inhibition of ACVI via binding to C1a when the level of Galpha(i) is low (i.e. around the IC(50) value) and that a more complicated interfering mode results when the level of Galpha(i) is high (i.e. approximately 10- to 20-fold of the IC(50) value). Collectively, data presented herein suggest a novel function of the N terminus of ACVI in Galpha(i)-mediated regulation.
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MESH Headings
- Adenylyl Cyclases/metabolism
- Animals
- Blotting, Western
- CHO Cells
- Catalytic Domain
- Cell Line
- Cell Membrane/metabolism
- Cricetinae
- Dose-Response Relationship, Drug
- Electrophoresis, Polyacrylamide Gel
- GTP-Binding Protein alpha Subunit, Gi2
- GTP-Binding Protein alpha Subunits, Gi-Go/metabolism
- Humans
- Inhibitory Concentration 50
- Leucine/chemistry
- Models, Biological
- Models, Molecular
- Mutagenesis, Site-Directed
- Mutation
- Plasmids/metabolism
- Polymerase Chain Reaction
- Protein Binding
- Protein Conformation
- Protein Isoforms
- Protein Structure, Secondary
- Protein Structure, Tertiary
- Proto-Oncogene Proteins/metabolism
- Rats
- Recombinant Proteins/chemistry
- Recombinant Proteins/metabolism
- Transfection
- Valine/chemistry
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Affiliation(s)
- Yu-Ya Kao
- Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan, ROC
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9
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Middleton LS, Cass WA, Dwoskin LP. Nicotinic receptor modulation of dopamine transporter function in rat striatum and medial prefrontal cortex. J Pharmacol Exp Ther 2003; 308:367-77. [PMID: 14563785 DOI: 10.1124/jpet.103.055335] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Nicotine activates nicotinic acetylcholine receptors (nAChRs) on dopamine (DA) terminals to evoke DA release, which subsequently is taken back up into the terminal via the DA transporter (DAT). nAChRs may modulate DAT function thereby contributing to the regulation of synaptic DA concentrations. The present study determined the dose-response for nicotine (0.1-0.8 mg/kg, s.c.) to modulate DA clearance in striatum and medial prefrontal cortex (mPFC) using in vivo voltammetry in urethane anesthetized rats and determined if this effect was mediated by nAChRs. Exogenous DA (200 microM) was pressure-ejected at 5-min intervals until reproducible baseline signals were obtained. Subsequently, nicotine or saline was administered, and DA pressure ejection continued at 5-min intervals for 60 min. In both striatum and mPFC, signal amplitude decreased by approximately 20% across the 60-min session in saline-injected rats. A monophasic dose-response curve was found in striatum, with a maximal 50% decrease in signal amplitude after 0.8 mg/kg. In contrast, a U-shaped dose-response curve was found in mPFC, with a maximal 50% decrease in signal amplitude after 0.4 mg/kg. Onset of nicotine response occurred 10 to 15 min after injection in both brain regions; however, the amount of time before maximal response was 45 and 30 min in striatum and mPFC, respectively. Mecamylamine (1.5 mg/kg) completely inhibited the nicotine-induced (0.8 and 0.4 mg/kg) decrease in signal amplitude in striatum and mPFC, respectively, indicating mediation by nAChRs. Thus, nicotine enhances DA clearance in striatum and mPFC in a mecamylamine-sensitive manner, indicating that nAChRs modulate DAT function in these brain regions.
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Affiliation(s)
- Lisa S Middleton
- College of Pharmacy, University of Kentucky, Lexington, Kentucky 40536, USA
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Gulley JM, Zahniser NR. Rapid regulation of dopamine transporter function by substrates, blockers and presynaptic receptor ligands. Eur J Pharmacol 2003; 479:139-52. [PMID: 14612145 DOI: 10.1016/j.ejphar.2003.08.064] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The extracellular actions of dopamine are terminated primarily through its binding to dopamine transporters and translocation back into dopamine neurons. The transporter thereby serves as an optimal target to regulate dopamine neurotransmission. Although acute pharmacological blockade of dopamine transporters is known to reversibly inhibit transporter function by preventing the binding of its endogenous substrate dopamine, it recently has become clear that dopamine transporter substrates, such as amphetamines, and blockers, such as cocaine, also have the ability to rapidly and persistently regulate transporter function after their direct pharmacological effect has subsided. Presynaptic receptor ligands can also regulate dopamine transporter function. This has been investigated most extensively for dopamine D2 receptors, but there is also evidence for regulation by gamma-aminobutyric acid (GABA) GABAB receptors, metabotropic glutamate, nicotinic acetylcholine, serotonin, sigma2- and kappa-opioid receptors. The focus of this review is the rapid, typically reversible, regulation of dopamine transporter velocity by substrates, blockers and presynaptic receptor ligands. The research discussed here suggests that a common mechanism through which these different classes of compounds regulate transporter activity is by altering the cell surface expression of dopamine transporters.
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Affiliation(s)
- Joshua M Gulley
- Department of Pharmacology and Neuroscience Program, University of Colorado Health Sciences Center, Campus Box C-236, 4200 E Ninth Avenue, Denver, CO 80262, USA.
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Huang CL, Huang NK, Shyue SK, Chern Y. Hydrogen peroxide induces loss of dopamine transporter activity: a calcium-dependent oxidative mechanism. J Neurochem 2003; 86:1247-59. [PMID: 12911632 DOI: 10.1046/j.1471-4159.2003.01936.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
H2O2 dose dependently inhibited dopamine uptake in PC12 cells and in striatal synaptosomes. Treatment with H2O2 resulted in a reversible reduction in Vmax, with no effect on its Km value. This suppressive effect of H2O2 could be relieved by reducing agents (dithiothreitol and cysteine). Furthermore, an oxidizer (dithiodipyridine) also markedly suppressed the dopamine transporter (DAT). Oxidative stress therefore might contribute to the action of H2O2. H2O2 appeared to modify DAT at both extracellular and intracellular sites because cumene-H2O2 (a radical generator mostly restricted to plasma membranes) at high concentrations also slightly suppressed DAT activity and the intracellular overexpression of catalase ameliorated the inhibitory effect of H2O2. Internalization was unlikely to be involved because concanavalin A, which blocked endocytosis, did not prevent the H2O2-evoked inhibition of DAT activity. Interestingly, H2O2 treatment evoked a Ca2+ influx in PC12 cells. Moreover, removal of external calcium by EGTA or reduction in the intracellular calcium level using BAPTA-AM reversed the inhibitory effect of H2O2. Conversely, depletion of intracellular calcium stores using thapsigargin did not affect the reduction in DAT activity by H2O2. Collectively, our results indicate that the DAT, one of the most important proteins controlling the dopaminergic system, is also a redox sensor. In addition, H2O2 might suppress the DAT by a Ca2+-dependent oxidative pathway.
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Affiliation(s)
- Chuen-Lin Huang
- Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan, Republic of China
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Serra PA, Rocchitta G, Delogu MR, Migheli R, Taras MG, Mura MP, Esposito G, Miele E, Desole MS, Miele M. Role of the nitric oxide/cyclic GMP pathway and extracellular environment in the nitric oxide donor-induced increase in dopamine secretion from PC12 cells: a microdialysis in vitro study. J Neurochem 2003; 86:1403-13. [PMID: 12950449 DOI: 10.1046/j.1471-4159.2003.01947.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In vitro microdialysis was used to investigate the mechanism of nitric oxide (NO) donor-induced changes in dopamine (DA) secretion from PC12 cells. Infusion of the NO-donor S-nitroso-N-acetylpenicillamine (SNAP, 1.0 mm) induced a long-lasting increase in DA and 3-methoxytyramine (3-MT) dialysate concentrations. SNAP-induced increases were inhibited either by pre-infusion of the soluble guanylate cyclase (sGC) inhibitor 1H-[1,2,4] oxadiazolo[4,3]quinoxalin-1-one (ODQ, 0.1 mm) or by Ca2+ omission. Ca2+ re-introduction restored SNAP effects. SNAP-induced increases in DA + 3-MT were unaffected by co-infusion of the l-type Ca2+ channel inhibitor nifedipine. The NO-donor (+/-)-(E)-4-ethyl-2-[(E)-hydroxyimino]-5-nitro-3-hexenamide (NOR-3, 1.0 mm) induced a short-lasting decrease in dialysate DA + 3-MT. Ascorbic acid (0.2 mm) co-infusion allowed NOR-3 to increase dialysate DA + 3-MT. ODQ pre-infusion inhibited NOR-3 + ascorbic acid-induced DA + 3-MT increases. Infusion of high K+ (75 mm) induced a 2.5-fold increase in dialysate DA + 3-MT. The increase was abolished by NOR-3 co-infusion. Conversely, co-infusion of ascorbic acid (0.2 mm) with NOR-3 + high K+ restored high K+ effects. Co-infusion of nifedipine inhibited high K+-induced DA + 3-MT increases. These results suggest that activation of the NO/sGC/cyclic GMP pathway may be the underlying mechanism of extracellular Ca2+-dependent effects of exogenous NO on DA secretion from PC12 cells. Extracellular Ca2+ entry may occur through nifedipine-insensitive channels. NO effects and DA concentrations in dialysates largely depend on both the timing of NO generation and the extracellular environment in which NO is generated.
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Frantz KJ, Hansson KJ, Stouffer DG, Parsons LH. 5-HT(6) receptor antagonism potentiates the behavioral and neurochemical effects of amphetamine but not cocaine. Neuropharmacology 2002; 42:170-80. [PMID: 11804613 DOI: 10.1016/s0028-3908(01)00165-4] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The localization of serotonin 5-HT(6) receptors in limbic and motor brain regions, and the high affinity of these receptors for several antipsychotic agents, suggest that they may be involved in motor activity, reward-related behaviors, and psychotic disorders. The present study characterized the effects of a novel 5-HT(6) receptor antagonist, SB 258510A, on psychostimulant-induced motor activity, self-administration, and increases in extracellular dopamine in the nucleus accumbens and frontal cortex of male Wistar rats. The locomotor-activating effects of amphetamine (1mg/kg) were dose-dependently enhanced by pretreatment with SB 258510A (3, 10mg/kg). Similarly, amphetamine self-administration was dose-dependently altered by SB 258510A in a manner indicative of enhanced reinforcing effects of amphetamine on both fixed and progressive ratio schedules of reinforcement. SB 258510A treatment had no effect on either cocaine-induced locomotor activity or cocaine self-administration. Dual-probe in vivo microdialysis revealed that pretreatment with 3mg/kg SB 258510A potentiated an amphetamine-induced increase in extracellular dopamine more robustly in the frontal cortex than in the nucleus accumbens. These data indicate that activation of 5-HT(6) receptors may regulate behaviors related to amphetamine but not cocaine, and point to the frontal cortex as a possible site of action for these effects.
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Affiliation(s)
- K J Frantz
- Department of Neuropharmacology CVN7, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
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14
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Wu GC, Lai HL, Lin YW, Chu YT, Chern Y. N-glycosylation and residues Asn805 and Asn890 are involved in the functional properties of type VI adenylyl cyclase. J Biol Chem 2001; 276:35450-7. [PMID: 11461898 DOI: 10.1074/jbc.m009704200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In this study, we demonstrate that type VI adenylyl cyclase (ACVI) is glycosylated in vivo. Treating HEK293 cells expressing ACVI with tunicamycin to block the addition of N-linked oligosaccharide or removing the N-linked oligosaccharide by in vitro peptidyl-N-glycosidase F digestion reduced the molecular mass of ACVI. Furthermore, tunicamycin treatment suppressed the forskolin-stimulated activity of ACVI. Mutation of either one or both potential N-glycosylation sites (Asn(805) and Asn(890), located on extracellular loops 5 and 6, respectively) also reduced the molecular mass of ACVI. Therefore, ACVI was glycosylated at both Asn(805) and Asn(890). Confocal analysis indicated that glycosylation was not required for the delivery of ACVI to the cell surface. Although no significant alterations in K(m) values for ATP or sensitivity to divalent cations were detected, the glycosylation-deficient ACVI mutant N805Q/N890Q-ACVI exhibited much lower forskolin-, Mn(2+)-, and Mg(2+)-stimulated cyclase activities than did wild-type ACVI. By contrast, the Galpha(s)-stimulated cyclase activities of wild-type ACVI and N805Q/N890Q-ACVI were indistinguishable. Furthermore, compared with wild-type ACVI, N805Q/N890Q-ACVI was less sensitive to inhibition mediated by dopamine D2 receptors or by protein kinase C. Collectively, glycosylation of ACVI not only affected its catalytic activity in an activator-dependent manner, but also altered its ability to be regulated by a Galpha(i) protein-coupled receptor or by protein kinase C.
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Affiliation(s)
- G C Wu
- Institute of Life Sciences, National Defense Medical Center, Taipei 104, Taiwan, Republic of China
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15
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Drew AE, Werling LL. Protein kinase C regulation of dopamine transporter initiated by nicotinic receptor activation in slices of rat prefrontal cortex. J Neurochem 2001; 77:839-48. [PMID: 11331413 DOI: 10.1046/j.1471-4159.2001.00293.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We previously reported that activation of nicotinic receptors causes an enhancement in amphetamine-stimulated release of dopamine via its transporter from slices of prefrontal cortex, but no such enhancement of release from slices of nucleus accumbens or striatum. The nicotinic receptors mediating the enhancement most likely contain alpha4 and beta2 subunits based upon pharmacological characterization. In this study, we sought to characterize the second messenger systems associated with the nicotine-mediated response. Sodium channel involvement was confirmed by the observation that tetrodotoxin blocked nicotine-mediated enhancement, whereas veratridine or elevated K(+) mimicked the enhancement seen with nicotine. Inclusion of EGTA blocked nicotine-mediated enhancement, suggesting that, even though no exogenous Ca(2+) was added, endogenous stores were required for the enhancement. The enhancement by nicotine was also abolished by the L-type voltage-dependent calcium channel (VDCC) antagonist nitrendipine, but not by the N-type VDCC antagonist omega-conotoxin GVIA. Finally, inhibition of protein kinase C also abolished the nicotine-mediated enhancement of amphetamine-stimulated dopamine release, whereas inhibitors of Ca(2+)/calmodulin kinase II did not. These findings establish that nicotine can exert selective effects on dopamine transporter activity in prefrontal cortex, an area involved in cognition and learning.
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Affiliation(s)
- A E Drew
- Department of Pharmacology, The George Washington University Medical Center, Washington DC 20037, USA
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16
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Fleckenstein AE, Gibb JW, Hanson GR. Differential effects of stimulants on monoaminergic transporters: pharmacological consequences and implications for neurotoxicity. Eur J Pharmacol 2000; 406:1-13. [PMID: 11011026 DOI: 10.1016/s0014-2999(00)00639-7] [Citation(s) in RCA: 178] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Many psychostimulants alter plasmalemmal monoaminergic transporter function. Some, such as cocaine, prevent the reuptake of newly released dopamine, serotonin or norepinephrine into their associated neurons. Others, such as the amphetamines, facilitate release of these transmitters into the extraneuronal space by causing a reversal of function of these carrier proteins. An understanding of how psychostimulants regulate the function of not only plasmalemmal, but also vesicular monoamine transporter function is important to appreciate the pharmacological and sometimes neurotoxic consequences of administering these drugs, as well as the physiological regulation of these carrier proteins. Hence, this review will describe recent ex vivo studies investigating the rapid and differential affects of several stimulants on both plasmalemmal and vesicular monoamine transporter function.
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Affiliation(s)
- A E Fleckenstein
- Department of Pharmacology and Toxicology, University of Utah, 30 South 2000 East, Rm 201, Salt Lake City, UT 84112, USA.
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17
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Abstract
The objective of this study was to determine whether nicotine could selectively influence dopamine levels in the prefrontal cortex as compared with other dopaminergic areas of brain. Using a superfusion system, we found that nicotine and other agonists at nicotinic acetylcholine receptors enhanced the release of radiolabeled dopamine that was stimulated by 10 microM amphetamine from slices prepared from rat prefrontal cortex. In contrast, nicotine had no effect on amphetamine-stimulated [(3)H]dopamine release from slices of nucleus accumbens nor striatum. Under the conditions used, which included no added calcium to exclude contribution by exocytotic release, nicotine had no effect on basal release of [(3)H]dopamine. The enhancement by nicotine was concentration-dependent, reaching a maximum at 5 microM, and producing less release at higher concentrations. Enhancement by nicotine was fully reversed by 30 microM dihydro-beta-erythroidine, and by 10 microM mecamylamine, but was not affected by alpha-bungarotoxin. The potencies of nicotine, epibatidine, cytisine, and A85380 to enhance amphetamine-stimulated dopamine release, as well as the sensitivity of nicotine enhanced release to antagonists, are consistent with mediation via a high-affinity nicotinic acetylcholine receptor containing alpha 4 and beta 2 subunits, the major species of nicotinic receptor in forebrain. Since low dopaminergic activity in prefrontal cortex is correlated with cognitive deficits in schizophrenia, our findings may help explain why these deficits are improved in schizophrenics by smoking or nicotine administration.
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Affiliation(s)
- A E Drew
- Department of Pharmacology, The George Washington University Medical Center, Washington, DC 20037, USA
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